Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 01/14/07


AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
AFDSGX 930 AM PST FRI JAN 12 2007

.SYNOPSIS...A COLD UPPER LEVEL TROUGH AND LOW PRESSURE SYSTEM WILL MOVE OVER SOUTHERN CALIFORNIA TODAY. SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS ARE POSSIBLE THROUGH THE AFTERNOON. THE TROUGH WILL MOVE EAST TONIGHT. GUSTY WINDS MAINLY IN THE MOUNTAINS AND DESERTS WILL DECREASE THIS EVENING. IT WILL BE VERY COLD AT NIGHT AND IN THE EARLY MORNING FOR THE NEXT FEW DAYS. AN OFFSHORE FLOW WILL DEVELOP LATE TONIGHT AND INCREASE SATURDAY MORNING WITH GUSTY NORTHEAST WINDS MAINLY INLAND AND IN THE MOUNTAINS. THE OFFSHORE FLOW WILL CONTINUE THROUGH THURSDAY.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES...

BUSY MORNING WITH SHORT TERM WEATHER CONCERNS. BACK EDGE OF THIS IMPULSE SHOULD BE EAST OF FORECAST AREA BY 1200 PST. MAIN TROUGH AXIS REMAINS OVER SOUTHWEST CALIFORNIA THROUGH TONIGHT....THEN MOVES EAST SATURDAY AFTERNOON. THIS RAISES CONCERN ABOUT WRAP AROUND MOISTURE/UPSLOPE CONDITIONS ON NORTH SLOPES OF SAN BERNARDINO MOUNTAINS AND WEST AND NORTHWEST FACING SLOPES OF REMAINING MOUNTAINS AS WELL AS CONVERGENCE AROUND ISLANDS AND INSTABILITY OVER WATER TONIGHT GENERATING CONVECTION OVER WATER THAT MOVES ACROSS COASTAL AREAS AND SAN DIEGO COUNTY INLAND VALLEYS. MAY BE UPPING POPS IN THIS AFTERNOON PACKAGE...THOUGH PRECIPITATION AMOUNTS WILL BE VERY LIGHT...SNOW FLURRIES FOR MOUNTAINS AND ICE PELLETS LOWER ELEVATIONS. A COUPLE OF OTHER CHANGES ANTICIPATED TO TONIGHT/SATURDAY MORNING FORECAST...WIND CHILL AND FREEZING TEMPERATURES. WIND SPEEDS/TEMPERATURES CURRENTLY IN FORECAST GENERATE WIND CHILL VALUES BETWEEN -12 AND -25 DEGREES OVER SAN BERNARDINO MOUNTAINS BETWEEN 4 PM AND 10 AM SATURDAY. MAY MAKE SOME ADDITIONAL ADJUSTMENTS TO WIND GRIDS FOR SATURDAY MORNING WHICH MIGHT SHORTEN THIS TIME SPAN. WIDESPREAD TEMPERATURES BELOW FREEZING ACROSS VALLEYS/DESERTS/AND COASTAL AREAS 1 AM TO 9 AM SATURDAY MORNING. STILL SORTING OUT WHICH AREAS WILL GET FREEZE WARNING AND WHICH WILL GET FROST ADVISORY...BUT LEANING TOWARDS FREEZE WARNING FOR INLAND EMPIRE/VALLEYS AND COACHELLA VALLEY AND FROST ADVISORY COASTAL AREAS AND SAN DIEGO COUNTY DESERTS.

MAY MAKE MINOR ADJUSTMENTS TO REMAINDER OF FORECAST THIS AFTERNOON BUT NOT ANTICIPATING ANY SIGNIFICANT CHANGES. A FIRE WEATHER WATCH WILL BE ISSUED FOR SUNDAY NIGHT THROUGH THURSDAY FOR INLAND VALLEYS AND MOUNTAINS. NORTHEAST WINDS GUSTING OVER 35 MPH EXPECTED FOR MONDAY AND TUESDAY PORTION WHILE RELATIVE HUMIDITY EXPECTED TO REMAIN VERY LOW THROUGH THURSDAY WITH WEAKER OFFSHORE FLOW PREVAILING. &&

.AVIATION... 12Z NKX SOUNDING INDICATES THE MARINE LAYER DEPTH WAS AROUND 7000 FEET THIS MORNING. MORNING ACARS SOUNDINGS FROM DEPARTURES OUT OF KSAN INDICATE THE INVERSION HAD LOWERED TO AROUND 6500 FEET BY SUNRISE WITH A STRONGER INVERSION SHOWING UP AROUND 12000 FEET. LAYERS OF STRATOCU OVER THE AREA WITH THE LOWEST SCATTERED LAYER AROUND 3000 FEET MSL WITH ANOTHER BROKEN LAYER AROUND 4000 FEET AND ANOTHER LAYER AROUND 6000 FEET. SATELLITE IMAGERY SHOWS RAPID CLEARING TAKING PLACE FROM THE NORTHWEST OVER THE NORTHERN AREAS WHICH SHOULD WORK ITS WAY SOUTHWARD DURING THE REST OF THE MORNING WITH MOST AREAS SCATTERING OUT BY AFTERNOON. EXPECT MOSTLY CLEAR CONDITIONS AT AREA AIRPORTS THIS AFTERNOON THROUGH SATURDAY.

MAIN PROBLEM WILL BE THE STRONG WEST TO NORTHWEST WINDS ACROSS THE MOUNTAINS THAT COULD PRODUCE SOME MOUNTAIN WAVE/ROTOR ACTIVITY ALONG THE LEE SIDE OF THE MOUNTAINS OVER THE COACHELLA VALLEY NEAR KPSP THROUGH THIS AFTERNOON AND EVENING. THE WINDS ARE EXPECTED TO BECOME NORTH TO NORTHEAST TONIGHT AND SATURDAY WITH THE MOUNTAIN WAVE/ROTOR MOVING TO THE LEE SIDE OF THE SAN BERNARDINO MOUNTAINS NEAR KONT AND KSBD SATURDAY MORNING.

&&

.MARINE... SMALL CRAFT ADVISORIES ARE IN EFFECT TODAY FOR STRONG POST FRONTAL WESTERLY WINDS FROM 15 TO 25 KTS. THE RESULTANT SHORT PERIOD WIND SWELL (4-5 SECONDS) COMBINED WITH AN INCREASING LONGER PERIOD WESTERLY SWELL (8-10 SECONDS) FROM 7 TO 9 FEET WILL PRODUCE HAZARDOUS BOATING CONDITIONS.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...

SNOW ADVISORY UNTIL 10 AM...HIGH DESERTS AND INLAND EMPIRE ABOVE 2000 FEET...SEE LAXWSWSGX.

SNOW AND BLOWING SNOW ADVISORY UNTIL 11 AM...SAN BERNARDINO AND RIVERSIDE COUNTY MOUNTAINS...SEE LAXWSWSGX. WIND ADVISORY FOR THE MOUNTAINS AND DESERTS THROUGH 8 PM. SEE LAXNPWSGX.

WIND CHILL ADVISORY TONIGHT...SAN BERNARDINO MOUNTAINS TO BE ISSUED AROUND 2 PM THIS AFTERNOON.

FROST ADVISORY LATE TONIGHT/SATURDAY MORNING...COASTAL SECTIONS...INLAND VALLEYS...COACHELLA VALLEY...SAN DIEGO COUNTY DESERT.

SMALL CRAFT ADVISORY THROUGH THE EVENING. SEE LAXCWFSGX.

HIGH RIP CURRENT RISK TODAY. SEE LAXSRFSGX.

FREEZE WATCH FOR THE INLAND VALLEYS AND LOWER DESERTS FROM SAT EVENING THROUGH MON MORNING. SEE LAXNPWSGX.

FIRE WEATHER WATCH SUNDAY NIGHT THROUGH THURSDAY...INLAND VALLEYS AND MOUNTAINS...TO BE ISSUED AROUND 2 PM THIS AFTERNON.

$$

PUBLIC/FIRE WEATHER...BALFOUR AVIATION/MARINE.......HORTON


AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
AFDLOT 1200 PM CST FRI JAN 12 2007

.UPDATE...

WE UPDATE THE FORECAST FOR TODAY AND EARLY TONIGHT. THIS WAS BASED ON RADAR ECHOS. THE SOUNDING AT DVN THIS MORNING SUGGEST DRIZZLE AND MAYBE SOME FREEZING DRIZZLE. IT IS DRY IN THE CRYSTAL GROWTH AREA. THE ACARS SOUNDING AT ORD SHOWS DRIZZLE FOR NOW. BUT AS THE COLD AIR MOVES IN THERE COULD BE SOME FREEZING DRIZZLE. WE DO NOT EXPECT MUCH FREEZING DRIZZLE AT THIS TIME. SO WE WILL NOT ISSUE AN ADVISORY AT THIS TIME. WE WILL WAIT UNTIL WE SEE HOW THE PRECIPITATION CONTINUES WHEN THE SURFACE TEMPERATURES GO BELOW FREEZING.

&&

.DISCUSSION FOR MORNING GRIDS/ZONES... 500 AM CST

SHORT WAVE HAS CONTINUED TO MOVE QUICKLY ACROSS THE GREAT LAKES AND IS NOW APPROACHING THE LOWER ST LAWRENCE VALLEY WHILE ANOTHER IS MOVING ACROSS SOUTHER ONTARIO ND A THIRD INTO MN. THE SURFACE COLD FRONT HAS BEEN SLOW IN ITS SOUTHEASTWARD ADVANCEMENT OVERNIGHT AND IS LOCATED FROM FAR SE WI INTO NORTHERN AND W CENTRAL IL EARLY THIS MORNING. WHILE COLDER AIR WILL BE ADVECTING INTO THE REGION AS THE BOUNDARY CONTINUES TO SLIP SOUTHEAST TODAY...EVENTUALLY REACHING THE OZARKS AND LOWER OH VALLEY BY 00Z SAT...THE COLD AIR WILL BE HELD OFF FOR A WHILE AS IT REMAINS ACROSS THE NORTHERN PLAINS AND NORTH WOODS INTO SOUTH CENTRAL CANADA AND THE CORE OF THE ARCTIC AIR STAYS IN NORTHERN CANADA WHILE SOUTHWESTERLY UPPER FLOW FROM THE WESTERN U.S. TROF REACHES NORTHEASTWARD ACROSS THE GREAT LAKES TO THE CANADIAN MARITIMES. SEVERAL FORECAST PROBLEMS THROUGH THE WEEKEND CONCERNING PRECIP TYPES AND TIMING. SHALLOWER COLD AIR WILL CONTINUE TO ADVECT OVER THE FA THE COLD HI PRES RIDGE BUILDS SLOWLY SE ACROSS THE DAKOTAS AND THE UPPER S VALLEY TODAY AND TONIGHT. THIS SHOULD COOL LOWER PORTION OF COLUMN TO SUPPORT SOME PL ACROSS THE NRN PARTS OF THE FA TODAY. WITH BOUNDARY WELL S...SFC WAVE TO TRAVEL ALONG IT LATER THIS AFTERNOON AND TONIGHT WILL KEEP MAIN PRECIP AREA ACROSS SRN AND CNTRL IL INTO MUCH OF IND...BUT WITH WSW FLO CONTINUING OVR THE FA AHEAD OF THE H8 TROF THE NORTHERN EDGE OF THE PRECIP SHIELD MAY ENCROACH INTO SOUTHERN AND EASTERN PORTIONS. THERMAL PROFILES SUGGEST A RANGE FROM LIGHT SNOW OR FLURRIES NW TRANSITIONING TO A BAND OF MIXED RAIN...SLEET AND FREEZING RAIN...THEN JUST RAIN IN THE FAR SE COUNTIES.

AS WESTERN UPPER TROF MOVES OVER THE ROCKIES AND OUT OVER THE PLAINS SUNDAY MODELS SUGGEST AN ELONGATED H8 CIRCULATION TO TREK FROM MO ACROSS CENTRAL IL AND TO SE LOWER MI BY 12Z MON. THIS PUTS THE REGION AT RISK FOR A SOMEWHAT SIGNIFICANT PRECIP EVENT FOR SUNDAY AND SUNDAY NIGHT. AGAIN...DEPTH OF COLD AIR IN LO LEVELS AND HOW MUCH WAA ADVECTION OCCURS ABOVE THIS COLD LAYER WILL DETERMINE WHERE PRECIP TRANSITIONS FROM PURE SN TO MIXED SNOW AND SLEET. ATTM THIS WOULD APPEAR TO BE ACROSS THE SRN PORTION OF THE FA AS MODELS ONLY INDICATING WEAK H8 FLOW NWRD OVER THE COLD DOME. NECESSITY FOR SOME SORT OF WINTER WX ADVISORIES FOR SNOW/SLEET/FREEZING RAIN LIKELY TO BE NECESSARY FOR AT LEAST PARTS OF FA BUT NEED TO HAVE DETAILS MORE CLEARLY INDICATED FOR THAT.

FOR FIRST PART OF NEXT WEEK COLD BUT CERTAINLY NOT OUT OF ORDINARY FOR MID JAN...AT LEAST DURING A MORE TYPICAL WINTER. COLD DOES NOT APPEAR TO BE VERY LONG LIVED AS BY LATE WEEK TEMPS MODERATE ONCE AGAIN WITH UPPER FLOW RETURNING TO OFF OF PACIFIC. TRS

&&

.AVIATION... 1200 PM CST

FOR THE 18Z TAFS...FRONTAL BOUNDARY SLOWLY MOVING SOUTH FROM CURRENT POSITION INVOF A ORD-PNT LINE. AS COLDER AIR ASSOCIATED WITH THIS BOUNDARY ENCOUNTERS THE VERY MOIST AIR OUT AHEAD OF THE FRONT...LIFR CIGS ARE RESULTING. SCT -SN/RA OVR SERN IA IS TRACKING NEWD AT 60KTS IN CONJUNCTION WITH A WEAK MID-LEVEL DISTURBANCE. AT CURRENT PACE...THIS PRECIP SHOULD REACH RFD AROUND 19Z AND ORD/MDW/DPA AROUND 20Z. LOW LEVEL TEMPS STILL ABV FREEZING BUT WILL BE DIPPING BELOW THAT BY EVENING IN THE RFD AREA. VERTICAL TEMP PROFILES COOL BELOW 0 DEG C AT THE CHICAGO AREA TERMINALS LATE THIS EVENING. SATURATED SUB-FREEZING LAYER BTWN THE SFC AND ~5KFT SHOULD ONLY BE ABOUT -5 TO -8C AT ITS COLDEST POINT. THUS...SNOWFLAKE GENERATION OVERNIGHT MAY BE HARD PRESSED TO HAPPEN...LEAVING SUPERCOOLED LIQUID (FZDZ) THE MOST LIKELY SCENARIO. HEAVIER PRECIP SHOULD REMAIN WELL SOUTH OF THE LOCAL TERMINALS THROUGH THE NEXT 24HRS. CIGS SHOULD CLIMB BACK INTO MVFR RANGE BY MORNING AS 1035-MB HIGH TO THE NW NUDGES DRIER AIR DEEPER INTO OUR AREA.

HANDEL

&&

.LOT WATCHES/WARNINGS/ADVISORIES... .IL...NONE. .IN...NONE. .LM...NONE. &&

$$


AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
AFDIWX 905 PM EST SAT JAN 13 2007

.UPDATE... UPDATED ZONES/GRIDS TO ADD MENTION OF PRECIP THIS EVE. HAVE SEEN A COUPLE WAVES OF DRIZZLE MOVE THROUGH THE AREA LATE THIS AFTN AND THIS EVE AS WK TROFS MOVG THROUGH THE FLOW PROVIDING SLIGHT ENHANCEMENT TO THE GENERAL OVER-RUNNING PATTERN IN PLACE. MORE SGFNT PRECIP OVER WEST CENTRAL IL HAS BEEN DIMINISHING AS IT MOVES NE THIS EVE AND 00Z SOUNDINGS ARE SHOWING SOME MID LEVEL DRYING HAS OCCURRED TODAY OVER OUR AREA. 00Z NAM SUGGESTS DEEPER MOISTURE AND PRECIP ASSOCIATED WITH SHRTWV SEEN ON WATER VAPOR LOOP MOVG THROUGH MO MAY NOT REACH US UNTIL CLOSE TO DAYBREAK. HWVR, WITH A COUPLE OF WAVES OF FREEZING DRIZZLE ALREADY MOVG THROUGH THE AREA, THINK IT`S LIKELY THAT MORE OF THIS LIGHT FREEZING PRECIP WILL OCCUR OVERNIGHT SO WILL HOLD ONTO THE ADVISORY ISSUED EARLIER FOR LATE TONIGHT AND SUNDAY, THOUGH ATTM APPEARS THE MOST SGFNT PRECIP DURING THIS ADVISORY MAY HOLD OFF UNTIL SUNDAY MORNING.

&&

.AVIATION... STNRY FRONT WAS OVER THE OHIO VALLEY THIS EVE. SHALLOW COLD AIRMASS WAS OVER NRN INDIANA WITH WARMER AIR ALOFT CONTINUING TO OVERRUN FRONT. THIS IS RESULTING IN WIDESPREAD IFR CONDITIONS NORTH OF THE FRONT WHICH SHOULD PERSIST THROUGH THE PERIOD. A WK TROF MOVG THROUGH THE AREA IS EXPECTED TO CAUSE A PERIOD OF DRIZZLE AND FREEZING DRIZZLE THIS EVE. SBN SHOULD STAY COLD ENOUGH FOR JUST FREEZING DRIZZLE, WHILE EXPECTING TEMPS WILL DROP ENOUGH AT FWA WITH DIURNAL COOLING AND WK LOW LEVEL CAA FOR DRIZZLE TO BEGIN FREEZE THIS EVE. AREA OF A LITTLE HEAVIER RAIN OVER WEST CENTRAL IL AND MO WAS ASSOCIATED WITH A SHRTWV SEEN ON WATER VAPOR LOOP LIFTING NE INTO SWRN MO. THIS PRECIP EXPECTED TO REACH TAF SITES 07Z-09Z. PRECIP SHOULD END AT SBN TOMORROW AFTN BUT LIKELY LINGER AT FWA THROUGH THE DAY DUE TO CLOSER PROXIMITY TO FRONT AND SFC WAVE MOVG ALONG IT. EXPECT SLIGHT DIURNAL CLIMB IN TEMPS TOMORROW WILL CHANGE FREEZING RAIN TO RAIN AT FWA BY AFTN.

&&

.SHORT TERM... TONIGHT AND SUNDAY

WILL SIDE MORE WITH THE 12Z NAM-WRF THAN THE 12Z GFS FOR THIS FORECAST PACKAGE. THE THERMAL PROFILES SEEM MORE PLAUSIBLE THAN THE GFS AS SEEN BY MOST CURRENT TAMDAR DATA.

AT 19Z...SFC ANALYSIS DEPICTED A NEARLY STATIONARY FRONTAL BOUNDARY NEAR THE OHIO RIVER. THIS FRONT WILL UNDULATE SOME OVER THE NEXT 24 HOURS AS WAVES OF SFC LOW PRESSURE RIPPLE NE ALONG IT. MEANWHILE...ARCTIC HIGH PRESSURE WAS SPRAWLED FROM ONTARIO WESTWARD INTO THE UPR MS RIVER VLY. COLDER AIR HAS MADE ITS WAY INTO THE NRN THIRD OF THE FCST VIA SFC NE FLOW. THE FORECAST DILEMMA FOR TONIGHT INTO SUNDAY WILL BE HOW FAR SOUTH THE FREEZING LINE WILL MOVE AND HOW THIS WILL AFFECT PCPN TYPE.

FOR TONIGHT...A TANDEM OF UPR LVL S/WVS WILL ROTATE NE INTO THE WRN GREAT LAKES AND OHIO VLY REGION FROM THE SRN PLAINS/LOWER MS RIVER VLY. THESE S/WVS WILL PROVIDE UPR SUPPORT FOR VERTICAL LIFT. IN ADDITION...MODELS INDICATE THAT WARM...MOIST ISENTROPIC LIFT WILL DEVELOP TONIGHT...CONTINUING INTO SUNDAY. THE COMBINATION OF THE LIFT FROM THE S/WVS AND THE LIFT FROM MOIST...WARM AIR ADVECTION WILL CAUSE PCPN TO BREAK OUT FROM W TO EAST OVERNIGHT. WITH TEMPS AT OR BELOW FREEZING ACRS THE NRN TWO THIRDS OF THE FCST AREA AND WITH A WARM TONGUE OF AIR EXPECTED ALOFT...PCPN WILL FALL IN THE FORM OF FREEZING RAIN AND SLEET. ICE ACCUMULATIONS FROM THE FREEZING RAIN WILL BE ON THE LIGHT SIDE OVERNIGHT...MEASURING 0.05 OF AN INCH OR LESS. HOWEVER...ANY ICE WILL BE A HAZARD TO TRAVEL. HENCE...WILL ISSUE WINTER WX AND FREEZING RAIN ADVISORIES FOR TONIGHT STARING AFTER MIDNIGHT. ON SUNDAY...THERE MAY BE A BRIEF LULL IN THE PCPN BY AFTN AS AFOREMENTIONED S/WVS PIVOT OFF TO THE NE. HOWEVER...ANOTHER DISTURBANCE AND STRONGER WAVE OF LOW PRESSURE WILL APCH THE OHIO VALLEY BY EARLY EVENING...SPREADING WIDESPREAD PCPN BACK INTO THE REGION. KEEPING THIS IN MIND...HAVE DECIDED TO KEEP LIKELY POPS FOR THE ENTIRE PERIOD. TEMPERATURES WILL ONLY WARM SLIGHTLY DURING THE DAY...PERHAPS 3 TO 5 DEGREES FROM MORNING LOWS. ANY FREEZING RAIN BY AFTN WILL PROBABLY NOT ACCUMULATE MUCH WITH TEMPS HOVERING IN THE 32 TO 34 DEGREE RANGE. TO KEEP HEADLINES SOMEWHAT SIMPLISTIC WILL EXTEND THE ADVISORY THROUGH THE ENTIRE DAY AS ICING WILL LIKELY OCCUR DURING THE MORNING HOURS (ANOTHER 0.05 OF AN INCH). ALSO...THIS WILL MATCH UP WITH THE LONG TERM FORECASTER/S PLAN TO ISSUE A WINTER STORM WATCH FOR THE SUNDAY NIGHT/MONDAY TIME FRAME DUE TO THE NEXT WEATHER SYSTEM TO AFFECT THE REGION.

&&

.LONG TERM... SUNDAY NIGHT THROUGH SATURDAY

VERY CHALLENGING LONG TERM WITH THE FOCUS CONTINUING TO LIE WITH POTENTIAL MAJOR MIXED PRECIP EVENT AT THE START OF THE PERIOD. WATER VAPOR IMAGERY THIS AFTERNOON SHOWING A WELL DEVELOPED MID/UPPER LEVEL TROUGH AND EMBEDDED CLOSED CIRCULATION OVER THE WESTERN CONUS. A DEEP PLUME OF SUB-TROPICAL MOISTURE EMANATING FROM THE LOW LATITUDES OF THE PACIFIC STRETCHES INTO THE CENTRAL CONUS IN ADVANCE OF THE WESTERN TROUGH WITH PWAT SOME 2-3 STDEV ABOVE NORMAL FOR JAN. THIS WILL SET THE STAGE FOR YET ANOTHER SIGNIFICANT QPF EVENT...ONLY THIS TIME THERE WILL BE A LOW LEVEL ARCTIC AIRMASS ATTEMPTING TO UNDERCUT THE CONTINUED WARM/MOIST SW FLOW ALOFT.

SIMILAR TO MIDNIGHT SHIFT...HAVE LEANED TOWARDS THE STRONGER AND FARTHER NW SOLUTION OF THE NAM OVER THE FLATTER AND SUPPRESSED GFS SOLUTION. THE NAM HAS SUPPORT FROM BOTH THE CANADIAN REGIONAL GEM AND THE UKMET FOR THE PAST SEVERAL RUNS. ON SUNDAY SHORTWAVE ENERGY AND ASSOCIATED HEIGHT FALLS EJECTING OUT OF MEAN WESTERN CONUS TROUGH WILL SPAWN ANOTHER SURFACE WAVE ALONG THE BAROCLINIC BOUNDARY STRETCHING FROM THE SOUTHERN PLAINS INTO THE OHIO VALLEY. BOTH NAM/GFS SHOW RAPIDLY STRENGTHENING UPPER LEVEL JET ACROSS THE GREAT LAKES SUN NGT IN ADVANCE OF TROUGH EJECTION WITH AREA OF STRONG UPPER LEVEL DIVERGENCE DEVELOPING WITHIN THE RIGHT ENTRANCE REGION OVER THE CWA. THE UPPER LEVEL SUPPORT COUPLED WITH LOW LEVEL ISENTROPIC ASCENT/THETA-E ADVECTION SHOULD SUPPORT A BROAD AREA OF LIFT SUN NGT INTO MON AM. GIVEN THE ANOMALOUS HIGH AVAILABLE MOISTURE WITHIN SUB-TROPICAL MOISTURE PLUME...FEEL ALL MODEL GUIDANCE MAY VERY WELL BE UNDER-FORECASTING QPF IN THE COLD SECTOR. SIGNIFICANT QPF OF A HALF INCH OR MORE IS POSSIBLE IN AREAS WHICH WILL BE AT OR BELOW FREEZING AT THE SURFACE...WITH HEAVIER AMOUNTS IN THE FAR SOUTHERN PART OF THE CWA WHERE DEEPER MOISTURE AND WARMER TEMPS ARE FORECAST.

NEXT QUESTION IS PTYPE. AGAIN...FAVORED THE NAM THERMAL PROFILES IN FAVOR OF A STRONGER AND FARTHER NORTH TRACK...WHICH WOULD IMPLY WARMER TEMPS ALOFT. NAM POINT SOUNDINGS FAVORABLE FOR FZRA AND IP ACROSS MUCH OF THE NORTHERN 2/3 OF THE CWA...WITH TENDENCY TOWARDS MORE SLEET FARTHER NORTH WITH A DEEPER NEAR SURFACE COLD LAYER. THE ONLY PORTION OF THE CWA WITH SOUNDINGS SUPPORT SNOW SUN NGT BASED ON CURRENT 12Z NAM RUN WOULD BE THE FAR NW CORNER FROM NEAR MCY TO BEH. FOLLOWING THIS TREND...HAVE REDUCED THE AMOUNT OF SNOW MENTION IN GRIDS AND INCREASED FZRA/IP MENTION. LEFT THE SOUTHERN 1/3 OF THE CWA AS MAINLY RAIN SUN NGT...POSSIBLY SOME FZRA LATE AS TEMPS COOL TO NEAR FREEZING. HAVE HOISTED A WINTER STORM WATCH FOR SUN NGT THROUGH MIDDAY MON FOR ROUGHLY THE NORTHERN 2/3 OF THE CWA FOR A COMBINATION OF FZRA AND SLEET...WITH SOME SNOW IN THE MIX AS WELL IN THE FAR NW. A FLOOD WATCH HAS ALSO BEEN HOISTED FOR THE SAME TIME FRAME ACROSS THE SOUTH FOR A COMBINATION OF POTENTIAL RIVER FLOODING AND ALSO POOR DRAINAGE TYPE FLOODING. STILL SOME UNCERTAINTY WITH EXACT TRACK AND SURFACE TEMPS...BUT IF THE EXPECTED GREATER QPF VERIFIES COULD SEE SIGNIFICANT ICE AND/OR SLEET ACCUMULATION FOR A PORTION OF THE CWA.

ON MONDAY SLOWER/WARMER NAM STILL FAVORS A MIXED BAG IN THE MORNING...THEN AS LOW/MID LEVEL CAA RAMPS UP IN THE AFTERNOON ANY REMAINING PRECIP SHOULD CHANGE TO ALL SNOW FROM NW TO SE. ATTENTION THEN TURNS TO LAKE EFFECT POTENTIAL. FROM LATE MON AFTERNOON THROUGH TUE NW FLOW OF MUCH COLDER AIR ARRIVES. 12Z NAM BUFKIT ANALYSIS SHOWING MODERATE COLLIER INDEX AND FAIRLY WELL ALIGNED NW FLOW WITH A GOOD AMOUNT OF AMBIENT SYNOPTIC SCALE MOISTURE BENEATH AN INVERSION CENTERED AROUND 7K FEET. INSTABILITY PARAMETERS AND PATTERN RECOGNITION POINT TOWARDS A POTENTIALLY DECENT LAKE EFFECT EVENT. THIS IS STILL SEVERAL DAYS OFF...AND WITH FOCUS ON SYNOPTIC EVENT STILL PLENTY OF TIME TO WATCH FUTURE MODEL TRENDS. FOR NOW HAVE INCREASED POPS TO LIKELY SE OF THE LAKE WITH A LARGE AREA OF CHANCE POPS IN AREAS FAVORED BY NW FLOW. LITTLE CHANGE TO REMAINDER OF FORECAST FROM TUE NGT THROUGH SAT.

&&

.AVIATION... COLD FRONTAL BOUNDARY HAS JUST ABOUT STALLED OUT NEAR THE OHIO RIVER THIS AFTERNOON. MOSAIC AND SURROUNDING RADARS INDICATE THAT PCPN HAS ENDED FOR THE MOST PART ACRS THE FCST AREA...AND DRY WX IS EXPECTED THROUGH AT LEAST 06Z SUNDAY. THEN...SVRL WEAK WX DISTURBANCES ALOFT...COMBINED WITH A RETURN TO ISENTROPIC LIFT/WARM MOIST ADVECTION...WILL CAUSE PCPN TO FORM AFTER 06Z...WITH AREAL COVERAGE INCREASING BY 12Z SUNDAY. COLDER AIR HAS FILTERED SOUTHWARD INTO FAR NRN INDIANA...AND TEMPERATURES AT OR BELOW FREEZING ARE EXPECTED AT THE TAF SITES FROM 06Z THROUGH AT LEAST 18Z. THE COLD AIR AT THE SFC IN CONJUNCTION WITH A BULGE OF WARMER AIR ALOFT WILL RESULT IN FZRA AND SLEET. AT THIS POINT...KSBN HAS THE BEST CHC FOR SOME SLEET WHILE KFWA SHOULD ONLY SEE FZRA. CIGS ARE IN THE IFR CATEGORY THIS AFTN...AND THEY WILL DROP INTO THE LIFR CATEGORY OVERNIGHT AFTER THE ONSET OF PCPN. VSBYS TOO WILL DROP INTO THE IFR RANGE IN ASSOCIATION WITH THE PCPN.

&&

.IWX WATCHES/WARNINGS/ADVISORIES... IN...FLOOD WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR INZ020-INZ022-INZ023-INZ024-INZ025-INZ026-INZ027-INZ032- INZ033-INZ034.

FREEZING RAIN ADVISORY FROM MIDNIGHT EST /11 PM CST/ TONIGHT TO 7 PM EST /6 PM CST/ SUNDAY FOR INZ008-INZ009-INZ013-INZ015- INZ016-INZ017-INZ018.

WINTER STORM WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR INZ003-INZ004-INZ005-INZ006-INZ007-INZ008-INZ009-INZ012- INZ013-INZ014-INZ015-INZ016-INZ017-INZ018.

WINTER WEATHER ADVISORY FROM MIDNIGHT EST /11 PM CST/ TONIGHT TO 7 PM EST /6 PM CST/ SUNDAY FOR INZ003-INZ004-INZ005-INZ006- INZ007-INZ012-INZ014.

MI...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR MIZ077-MIZ078-MIZ079-MIZ080-MIZ081.

WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST SUNDAY FOR MIZ077-MIZ078-MIZ079-MIZ080-MIZ081.

OH...FLOOD WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR OHZ016-OHZ024-OHZ025.

FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST SUNDAY FOR OHZ001-OHZ002-OHZ004-OHZ005-OHZ015.

WINTER STORM WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR OHZ001-OHZ002-OHZ004-OHZ005-OHZ015.

LM...NONE. &&

$$

SHORT TERM...HICKMAN LONG TERM....HITCHCOCK AVIATION/UPDATE...TAYLOR


AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
AFDIWX 650 PM EST SAT JAN 13 2007

.AVIATION... STNRY FRONT WAS OVER THE OHIO VALLEY THIS EVE. SHALLOW COLD AIRMASS WAS OVER NRN INDIANA WITH WARMER AIR ALOFT CONTINUING TO OVERRUN FRONT. THIS IS RESULTING IN WIDESPREAD IFR CONDITIONS NORTH OF THE FRONT WHICH SHOULD PERSIST THROUGH THE PERIOD. A WK TROF MOVG THROUGH THE AREA IS EXPECTED TO CAUSE A PERIOD OF DRIZZLE AND FREEZING DRIZZLE THIS EVE. SBN SHOULD STAY COLD ENOUGH FOR JUST FREEZING DRIZZLE, WHILE EXPECTING TEMPS WILL DROP ENOUGH AT FWA WITH DIURNAL COOLING AND WK LOW LEVEL CAA FOR DRIZZLE TO BEGIN FREEZE THIS EVE. AREA OF A LITTLE HEAVIER RAIN OVER WEST CENTRAL IL AND MO WAS ASSOCIATED WITH A SHRTWV SEEN ON WATER VAPOR LOOP LIFTING NE INTO SWRN MO. THIS PRECIP EXPECTED TO REACH TAF SITES 07Z-09Z. PRECIP SHOULD END AT SBN TOMORROW AFTN BUT LIKELY LINGER AT FWA THROUGH THE DAY DUE TO CLOSER PROXIMITY TO FRONT AND SFC WAVE MOVG ALONG IT. EXPECT SLIGHT DIURNAL CLIMB IN TEMPS TOMORROW WILL CHANGE FREEZING RAIN TO RAIN AT FWA BY AFTN.

&&

.SHORT TERM... TONIGHT AND SUNDAY

WILL SIDE MORE WITH THE 12Z NAM-WRF THAN THE 12Z GFS FOR THIS FORECAST PACKAGE. THE THERMAL PROFILES SEEM MORE PLAUSIBLE THAN THE GFS AS SEEN BY MOST CURRENT TAMDAR DATA.

AT 19Z...SFC ANALYSIS DEPICTED A NEARLY STATIONARY FRONTAL BOUNDARY NEAR THE OHIO RIVER. THIS FRONT WILL UNDULATE SOME OVER THE NEXT 24 HOURS AS WAVES OF SFC LOW PRESSURE RIPPLE NE ALONG IT. MEANWHILE...ARCTIC HIGH PRESSURE WAS SPRAWLED FROM ONTARIO WESTWARD INTO THE UPR MS RIVER VLY. COLDER AIR HAS MADE ITS WAY INTO THE NRN THIRD OF THE FCST VIA SFC NE FLOW. THE FORECAST DILEMMA FOR TONIGHT INTO SUNDAY WILL BE HOW FAR SOUTH THE FREEZING LINE WILL MOVE AND HOW THIS WILL AFFECT PCPN TYPE.

FOR TONIGHT...A TANDEM OF UPR LVL S/WVS WILL ROTATE NE INTO THE WRN GREAT LAKES AND OHIO VLY REGION FROM THE SRN PLAINS/LOWER MS RIVER VLY. THESE S/WVS WILL PROVIDE UPR SUPPORT FOR VERTICAL LIFT. IN ADDITION...MODELS INDICATE THAT WARM...MOIST ISENTROPIC LIFT WILL DEVELOP TONIGHT...CONTINUING INTO SUNDAY. THE COMBINATION OF THE LIFT FROM THE S/WVS AND THE LIFT FROM MOIST...WARM AIR ADVECTION WILL CAUSE PCPN TO BREAK OUT FROM W TO EAST OVERNIGHT. WITH TEMPS AT OR BELOW FREEZING ACRS THE NRN TWO THIRDS OF THE FCST AREA AND WITH A WARM TONGUE OF AIR EXPECTED ALOFT...PCPN WILL FALL IN THE FORM OF FREEZING RAIN AND SLEET. ICE ACCUMULATIONS FROM THE FREEZING RAIN WILL BE ON THE LIGHT SIDE OVERNIGHT...MEASURING 0.05 OF AN INCH OR LESS. HOWEVER...ANY ICE WILL BE A HAZARD TO TRAVEL. HENCE...WILL ISSUE WINTER WX AND FREEZING RAIN ADVISORIES FOR TONIGHT STARING AFTER MIDNIGHT. ON SUNDAY...THERE MAY BE A BRIEF LULL IN THE PCPN BY AFTN AS AFOREMENTIONED S/WVS PIVOT OFF TO THE NE. HOWEVER...ANOTHER DISTURBANCE AND STRONGER WAVE OF LOW PRESSURE WILL APCH THE OHIO VALLEY BY EARLY EVENING...SPREADING WIDESPREAD PCPN BACK INTO THE REGION. KEEPING THIS IN MIND...HAVE DECIDED TO KEEP LIKELY POPS FOR THE ENTIRE PERIOD. TEMPERATURES WILL ONLY WARM SLIGHTLY DURING THE DAY...PERHAPS 3 TO 5 DEGREES FROM MORNING LOWS. ANY FREEZING RAIN BY AFTN WILL PROBABLY NOT ACCUMULATE MUCH WITH TEMPS HOVERING IN THE 32 TO 34 DEGREE RANGE. TO KEEP HEADLINES SOMEWHAT SIMPLISTIC WILL EXTEND THE ADVISORY THROUGH THE ENTIRE DAY AS ICING WILL LIKELY OCCUR DURING THE MORNING HOURS (ANOTHER 0.05 OF AN INCH). ALSO...THIS WILL MATCH UP WITH THE LONG TERM FORECASTER/S PLAN TO ISSUE A WINTER STORM WATCH FOR THE SUNDAY NIGHT/MONDAY TIME FRAME DUE TO THE NEXT WEATHER SYSTEM TO AFFECT THE REGION.

&&

.LONG TERM... SUNDAY NIGHT THROUGH SATURDAY

VERY CHALLENGING LONG TERM WITH THE FOCUS CONTINUING TO LIE WITH POTENTIAL MAJOR MIXED PRECIP EVENT AT THE START OF THE PERIOD. WATER VAPOR IMAGERY THIS AFTERNOON SHOWING A WELL DEVELOPED MID/UPPER LEVEL TROUGH AND EMBEDDED CLOSED CIRCULATION OVER THE WESTERN CONUS. A DEEP PLUME OF SUB-TROPICAL MOISTURE EMANATING FROM THE LOW LATITUDES OF THE PACIFIC STRETCHES INTO THE CENTRAL CONUS IN ADVANCE OF THE WESTERN TROUGH WITH PWAT SOME 2-3 STDEV ABOVE NORMAL FOR JAN. THIS WILL SET THE STAGE FOR YET ANOTHER SIGNIFICANT QPF EVENT...ONLY THIS TIME THERE WILL BE A LOW LEVEL ARCTIC AIRMASS ATTEMPTING TO UNDERCUT THE CONTINUED WARM/MOIST SW FLOW ALOFT.

SIMILAR TO MIDNIGHT SHIFT...HAVE LEANED TOWARDS THE STRONGER AND FARTHER NW SOLUTION OF THE NAM OVER THE FLATTER AND SUPPRESSED GFS SOLUTION. THE NAM HAS SUPPORT FROM BOTH THE CANADIAN REGIONAL GEM AND THE UKMET FOR THE PAST SEVERAL RUNS. ON SUNDAY SHORTWAVE ENERGY AND ASSOCIATED HEIGHT FALLS EJECTING OUT OF MEAN WESTERN CONUS TROUGH WILL SPAWN ANOTHER SURFACE WAVE ALONG THE BAROCLINIC BOUNDARY STRETCHING FROM THE SOUTHERN PLAINS INTO THE OHIO VALLEY. BOTH NAM/GFS SHOW RAPIDLY STRENGTHENING UPPER LEVEL JET ACROSS THE GREAT LAKES SUN NGT IN ADVANCE OF TROUGH EJECTION WITH AREA OF STRONG UPPER LEVEL DIVERGENCE DEVELOPING WITHIN THE RIGHT ENTRANCE REGION OVER THE CWA. THE UPPER LEVEL SUPPORT COUPLED WITH LOW LEVEL ISENTROPIC ASCENT/THETA-E ADVECTION SHOULD SUPPORT A BROAD AREA OF LIFT SUN NGT INTO MON AM. GIVEN THE ANOMALOUS HIGH AVAILABLE MOISTURE WITHIN SUB-TROPICAL MOISTURE PLUME...FEEL ALL MODEL GUIDANCE MAY VERY WELL BE UNDER-FORECASTING QPF IN THE COLD SECTOR. SIGNIFICANT QPF OF A HALF INCH OR MORE IS POSSIBLE IN AREAS WHICH WILL BE AT OR BELOW FREEZING AT THE SURFACE...WITH HEAVIER AMOUNTS IN THE FAR SOUTHERN PART OF THE CWA WHERE DEEPER MOISTURE AND WARMER TEMPS ARE FORECAST.

NEXT QUESTION IS PTYPE. AGAIN...FAVORED THE NAM THERMAL PROFILES IN FAVOR OF A STRONGER AND FARTHER NORTH TRACK...WHICH WOULD IMPLY WARMER TEMPS ALOFT. NAM POINT SOUNDINGS FAVORABLE FOR FZRA AND IP ACROSS MUCH OF THE NORTHERN 2/3 OF THE CWA...WITH TENDENCY TOWARDS MORE SLEET FARTHER NORTH WITH A DEEPER NEAR SURFACE COLD LAYER. THE ONLY PORTION OF THE CWA WITH SOUNDINGS SUPPORT SNOW SUN NGT BASED ON CURRENT 12Z NAM RUN WOULD BE THE FAR NW CORNER FROM NEAR MCY TO BEH. FOLLOWING THIS TREND...HAVE REDUCED THE AMOUNT OF SNOW MENTION IN GRIDS AND INCREASED FZRA/IP MENTION. LEFT THE SOUTHERN 1/3 OF THE CWA AS MAINLY RAIN SUN NGT...POSSIBLY SOME FZRA LATE AS TEMPS COOL TO NEAR FREEZING. HAVE HOISTED A WINTER STORM WATCH FOR SUN NGT THROUGH MIDDAY MON FOR ROUGHLY THE NORTHERN 2/3 OF THE CWA FOR A COMBINATION OF FZRA AND SLEET...WITH SOME SNOW IN THE MIX AS WELL IN THE FAR NW. A FLOOD WATCH HAS ALSO BEEN HOISTED FOR THE SAME TIME FRAME ACROSS THE SOUTH FOR A COMBINATION OF POTENTIAL RIVER FLOODING AND ALSO POOR DRAINAGE TYPE FLOODING. STILL SOME UNCERTAINTY WITH EXACT TRACK AND SURFACE TEMPS...BUT IF THE EXPECTED GREATER QPF VERIFIES COULD SEE SIGNIFICANT ICE AND/OR SLEET ACCUMULATION FOR A PORTION OF THE CWA.

ON MONDAY SLOWER/WARMER NAM STILL FAVORS A MIXED BAG IN THE MORNING...THEN AS LOW/MID LEVEL CAA RAMPS UP IN THE AFTERNOON ANY REMAINING PRECIP SHOULD CHANGE TO ALL SNOW FROM NW TO SE. ATTENTION THEN TURNS TO LAKE EFFECT POTENTIAL. FROM LATE MON AFTERNOON THROUGH TUE NW FLOW OF MUCH COLDER AIR ARRIVES. 12Z NAM BUFKIT ANALYSIS SHOWING MODERATE COLLIER INDEX AND FAIRLY WELL ALIGNED NW FLOW WITH A GOOD AMOUNT OF AMBIENT SYNOPTIC SCALE MOISTURE BENEATH AN INVERSION CENTERED AROUND 7K FEET. INSTABILITY PARAMETERS AND PATTERN RECOGNITION POINT TOWARDS A POTENTIALLY DECENT LAKE EFFECT EVENT. THIS IS STILL SEVERAL DAYS OFF...AND WITH FOCUS ON SYNOPTIC EVENT STILL PLENTY OF TIME TO WATCH FUTURE MODEL TRENDS. FOR NOW HAVE INCREASED POPS TO LIKELY SE OF THE LAKE WITH A LARGE AREA OF CHANCE POPS IN AREAS FAVORED BY NW FLOW. LITTLE CHANGE TO REMAINDER OF FORECAST FROM TUE NGT THROUGH SAT.

&&

.AVIATION... COLD FRONTAL BOUNDARY HAS JUST ABOUT STALLED OUT NEAR THE OHIO RIVER THIS AFTERNOON. MOSAIC AND SURROUNDING RADARS INDICATE THAT PCPN HAS ENDED FOR THE MOST PART ACRS THE FCST AREA...AND DRY WX IS EXPECTED THROUGH AT LEAST 06Z SUNDAY. THEN...SVRL WEAK WX DISTURBANCES ALOFT...COMBINED WITH A RETURN TO ISENTROPIC LIFT/WARM MOIST ADVECTION...WILL CAUSE PCPN TO FORM AFTER 06Z...WITH AREAL COVERAGE INCREASING BY 12Z SUNDAY. COLDER AIR HAS FILTERED SOUTHWARD INTO FAR NRN INDIANA...AND TEMPERATURES AT OR BELOW FREEZING ARE EXPECTED AT THE TAF SITES FROM 06Z THROUGH AT LEAST 18Z. THE COLD AIR AT THE SFC IN CONJUNCTION WITH A BULGE OF WARMER AIR ALOFT WILL RESULT IN FZRA AND SLEET. AT THIS POINT...KSBN HAS THE BEST CHC FOR SOME SLEET WHILE KFWA SHOULD ONLY SEE FZRA. CIGS ARE IN THE IFR CATEGORY THIS AFTN...AND THEY WILL DROP INTO THE LIFR CATEGORY OVERNIGHT AFTER THE ONSET OF PCPN. VSBYS TOO WILL DROP INTO THE IFR RANGE IN ASSOCIATION WITH THE PCPN.

&&

.IWX WATCHES/WARNINGS/ADVISORIES... IN...FLOOD WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR INZ020-INZ022-INZ023-INZ024-INZ025-INZ026-INZ027-INZ032- INZ033-INZ034.

FREEZING RAIN ADVISORY FROM MIDNIGHT EST /11 PM CST/ TONIGHT TO 7 PM EST /6 PM CST/ SUNDAY FOR INZ008-INZ009-INZ013-INZ015- INZ016-INZ017-INZ018.

WINTER STORM WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR INZ003-INZ004-INZ005-INZ006-INZ007-INZ008-INZ009-INZ012- INZ013-INZ014-INZ015-INZ016-INZ017-INZ018.

WINTER WEATHER ADVISORY FROM MIDNIGHT EST /11 PM CST/ TONIGHT TO 7 PM EST /6 PM CST/ SUNDAY FOR INZ003-INZ004-INZ005-INZ006- INZ007-INZ012-INZ014.

MI...WINTER STORM WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR MIZ077-MIZ078-MIZ079-MIZ080-MIZ081.

WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST SUNDAY FOR MIZ077-MIZ078-MIZ079-MIZ080-MIZ081.

OH...FLOOD WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR OHZ016-OHZ024-OHZ025.

FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST SUNDAY FOR OHZ001-OHZ002-OHZ004-OHZ005-OHZ015.

WINTER STORM WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR OHZ001-OHZ002-OHZ004-OHZ005-OHZ015.

LM...NONE. &&

$$

SHORT TERM...HICKMAN LONG TERM....HITCHCOCK AVIATION...TAYLOR


AREA FORECAST DISCUSSION
NWS WICHITA KS
AFDICT 948 PM CST SAT JAN 13 2007

.UPDATE... A VERY LIGHT FREEZING MIST/DRIZZLE HAS BEEN REPORTED INTERMITTENTLY ACROSS PORTIONS OF THE FLINT HILLS INTO THE WICHITA AREA...AND SUPPORTED BY AREA SOUNDINGS. SO SENT A QUICK UPDATE OUT.

KED

&&

.PREV DISCUSSION... /ISSUED 811 PM CST SAT JAN 13 2007/

UPDATE... HAVE CONTINUED TO TREND POPS DOWN FOR MUCH OF THE NIGHT...AS WE WILL BE IN A LULL UNTIL MAIN UPPER TROF EJECTS NORTHEAST ON SUNDAY. THAT SAID...WILL CONTINUE TO SHOW RAPID INCREASE IN POPS AGAIN BY 12Z ACROSS PORTIONS OF CENTRAL AND SOUTH CENTRAL KANSAS AS PREVIOUS FORECASTER HAD SHOWN IN GRIDS/FORECAST. NOT MUCH IN THE WAY OF WEATHER PROBLEMS FROM ANY PRECIPITATION OVERNIGHT...THOUGH THE WAY HAS BEEN PAVED TO STAY WITH THE WINTER STORM WARNING TO AVOID CONFUSION...WITH MODEST EXPECTATIONS TO REALIZE CRITERIA ON SUNDAY IN LAST 12 HOURS OF VALID TIME. OTHERWISE...ONLY SLIGHT TWEAKS TO TEMPERATURES/WINDS FOR TONIGHT.

KED

PREV DISCUSSION... /ISSUED 253 PM CST SAT JAN 13 2007/

SYNOPSIS...

SIGNIFICANT CONCERNS OVER VALIDITY OF LATEST MODEL RUNS. OF PARTICULAR NOTE IS DEARTH OF OBSERVATIONAL DATA ACROSS SOUTHWESTERN US...ESPECIALLY SOUTHERN NEVADA/NORTHWEST AZ/UT. ACARS DATA AROUND 1200 UTC IS EVEN LACKING. GIVEN MOST PRECIPITATION HAS BEEN DRIVEN BY WEAKER RIPPLES OVER HIGHLY BAROCLINIC LOW LEVELS... CONFIDENCE IS GOING TO BE LOW. ALSO OF NOTE...WATER VAPOR LOOP SUGGEST DECENT AMOUNT OF ENERGY ABOUT TO ROUND THE CLOUD BASE OF LONG WAVE TROUGH WELL OFF GULF OF CA. HOW WELL THIS WILL BE HANDLED IS ALSO SUSPECT. ON THE PLUS SIDE...LATEST RUNS SOMEWHAT SIMILAR TO YESTERDAYS RUNS...WHICH AT LEAST MEANS NO BIG CHANGES FROM PREVIOUS THINKING.

DISCUSSION...

TONIGHT-SUN:

PLAN TO KEEP HEADLINES GOING...ALTHOUGH MAKING CRITERIA MAY BE MARGINAL. FORCING WILL BE ON THE WANE TONIGHT ONCE CURRENT BATCH OF PRECIPITATION EAST OF I-35 MOVES OUT...WITH LIGHT PRECIPITATION ANTICIPATED FOR REMAINDER OF THE NIGHT. PRECIPITATION TYPE WILL LIKELY BE SOME COMBO OF LIGHT SNOW/LIGHT ICE PELLETS/LIGHT FREEZING DRIZZLE. NEXT SIGNIFICANT SHORTWAVE WILL ENTER SOUTHWEST CORNER OF FORECAST AREA AROUND 1200 UTC...AND SPREAD NE DURING THE DAY. MAIN CONCERN IS AREA WEST OF A LINE FROM KINGMAN TO MCPHERSON...WHERE MARGINALLY DECENT LAPSE RATES AND PERSISTENCE OF LIFT WILL BE MAXIMIZED. 1200 UTC RUNS CONTINUE TO FORECAST A COUPLED UPPER JET SO WILL ALSO BE DECENT UPPER SUPPORT. JUST NOT ENOUGH CONFIDENCE IN LAPSE RATES AND LIFT TO REALLY JUMP ON SNOW AMOUNTS...ESPECIALLY IF FAIR AMOUNT OF THE PRECIPITATION IS SLEET. MINIMUM WILL LIKELY BE AROUND ICT AND AREAS IMMEDIATELY SOUTH. IN SOUTHEAST KS PRECIPITATION WILL START LATE MORNING AND PERSIST INTO THE EVENING. AGAIN SLIGHTLY LONGER PERSISTENCE WILL ADD ACCUMULATION. WITH THERMAL PROFILE NOT EXPECTED TO CHANGE SIGNIFICANTLY...EXPECT A COMBO OF TYPE THERE AS WELL.

SUN NIGHT-MON:

PRECIPITATION WILL MOST LIKELY BE ON THE WANE BY MIDNIGHT. CAVEAT MAY BE IF LAGGING UPPER WAVE DOES SLOW OVERALL PROGRESSION DOWN... PRECIPITATION MAY LINGER INTO MON. GOING CONSENSUS WAS TO NIX PRECIPITATION.

TUE-SAT:

EARLY IN THIS PERIOD MAIN CONCERN WILL BE COLD TEMPERATURES WITH GOOD DIURNAL COOLING FOLLOWED BY MODERATING TEMPERATURES WITH ARCTIC AIRMASS OVER THE AREA. HOW LONG/HOW PRONOUNCED THESE IMPACTS WILL BE WILL BE HIGHLY DEPENDENT ON WHAT OCCURS IN THE NEXT 24-36 HOURS. LATER IN THE PERIOD...GIVEN HIGH LEVEL OF UNCERTAINTY WITH ONGOING PATTERN CHANGE AND ANOTHER PATTERN CHANGE IN THE OFFING FOR LATE IN THE WEEK...OPTED NOT TO INTRO PRECIPITATION CHANCES JUST YET ON DAY 7. AT FACE VALUE...BOTH 0600 UTC GLOBAL FORECAST SYSTEM MODEL/00 UTC EUROPEAN CENTRE FOR MEDIUM RANGE WEATHER FORECASTS MODEL WOULD SUGGEST SOME OVERRUNNING PRECIPITATION NORTH OF FRONTAL BOUNDARY WHICH WOULD MOVE THROUGH THE AREA THU AFTERNOON PER GLOBAL FORECAST SYSTEM MODEL OR LATE FRI AFTERNOON OR EVENING PER EUROPEAN CENTRE FOR MEDIUM RANGE WEATHER FORECASTS MODEL. THE LATTER IS 12 HOUR EARLIER THAN PREVIOUS RUN. DEPTH...TIMING AND ORIENTATION OF LONGWAVE TROUGH OVER WESTERN US ARE STILL UNCERTAIN AS WELL. AT THIS POINT...DOES NOT APPEAR TO BE A MAJOR SURFACE CYCLONE IN THE OFFING WITH THIS UPPER SYSTEM...SO PRECIPITATION WILL BE DEPENDENT ON SUBTLE ORIENTATION OF WINDS AND THERMAL GRADIENT. -HOWERTON

&&

.PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 13 16 10 19 / 40 100 30 10 HUTCHINSON 11 15 9 18 / 40 100 40 10 NEWTON 12 16 9 18 / 30 100 40 10 ELDORADO 12 17 10 19 / 40 100 40 10 WINFIELD-KWLD 15 19 11 20 / 50 100 20 0 RUSSELL 10 15 7 16 / 40 100 60 10 GREAT BEND 11 15 8 16 / 50 100 50 10 SALINA 11 15 8 17 / 30 100 60 10 MCPHERSON 11 15 9 17 / 30 100 50 10 COFFEYVILLE 18 23 14 22 / 60 100 30 10 CHANUTE 16 21 13 21 / 60 100 30 10 IOLA 15 20 13 20 / 60 100 30 10 PARSONS-KPPF 17 22 14 22 / 60 100 30 10

&&

.ICT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR KSZ032-033- 047>053-067>072-082-083-091>096-098>100.

&&

$$


AREA FORECAST DISCUSSION
NWS TOPEKA KS
AFDTOP 907 PM CST SAT JAN 13 2007

.DISCUSSION... WILL UPDATE THE FORECAST SHORTLY FOR CURRENT CONDITIONS. FOR THE MOST PART...PRECIP HAS ENDED ACROSS MOST OF THE FORECAST AREA. THERE ARE SOME SMALL BANDS OF VERY LIGHT PRECIP SEEN ON RADAR. IT IS HARD TO TELL IF THE PRECIP FALLING IS LIGHT FREEZING DRIZZLE OR POSSIBLY SNOW NEEDLES...ITS THAT LIGHT. THE LATEST RUC FORECAST WAS SHOWING SOME VERY LIGHT ISENTROPIC LIFT WITHIN THE CLOUD. THINK THIS MAY BE THE REASON FOR THE LIGHT PRECIP. NEVERTHELESS DO NOT ANTICIPATE ANY ACCUMULATING PRECIP FOR THE REST OF THE NIGHT SINCE LARGE SCALE FORCING HAS LEFT THE AREA FOR THE TIME BEING.

MAIN QUESTION IS WHAT TO DO WITH THE WATCH. AM CONSIDERING REPLACING THE WATCH WITH AN ADVISORY OF SOME SORT. THE 00Z NAM IS COMING IN SHOWING A SIMILAR SOLUTION TO THE DAY TIME RUNS. AS THE BASE OF THE UPPER LEVEL TROUGH ROTATES THROUGH THE SOUTHER ROCKIES AND INTO THE WESTERN CENTRAL PLAINS...LARGE SCALE FORCING IS EXPECTED TO AFFECT THE AREA ONCE AGAIN. HOWEVER THE FORCING DOES NOT LOOK TERRIBLY IMPRESSIVE WITH THE UPPER WAVE SHEARING OUT AS IT MOVES INTO THE PLAINS. WILL WAIT TO REPLACE THE WATCH AND PEEK AT THE 00Z GFS TO SEE IF IT SHOWS SOMETHING DIFFERENT FROM THE EARLIER RUNS. IF THE NAM IS CORRECT...LOOKS LIKE MAINLY SNOW WILL FALL ACROSS AREAS NORTH AND WEST OF MHK WITH AROUND 2 INCHES POSSIBLE. ALONG THE TURNPIKE WILL BE A LITTLE MORE PROBLEMATIC GIVEN FORECAST SOUNDINGS STILL SHOWING A WARM NOSE AROUND 800MB THROUGH 21Z. WILL KEEP THE WINTER STORM WARNING AS IS FOR THE TIME BEING...GIVEN THE POSSIBILITY FOR DECENT SLEET ACCUMULATIONS ONCE AGAIN.

AVIATION WISE...EXPECT CURRENT CONDITIONS TO REMAIN RELATIVELY STABLE THROUGH THE OVERNIGHT PERIOD. OBVIOUSLY THE LIGHT PRECIP SEEN ON RADAR WILL CAUSE A PROBLEM FOR AIRCRAFT. THIS SHOULD BE SPOTTY THOUGH AND CONFINED TO AREAS BELOW 4000FT. SFC VIS WILL DROP TO AROUND 4SM IN THESE LIGHT BANDS WITH CEILINGS AROUND 800FT. OTHERWISE ANTICIPATE A SLIGHT IMPROVEMENT TO THE CEILINGS AROUND 1000FT AS VERY WEAK ISENTROPIC LIFT BREAKS DOWN.

&&

WOLTERS

.PREV DISCUSSION /340 PM CST SAT JAN 13 2007/... CURRENTLY...SLEET SHOWERS EXITING THE CWA TO THE EAST WITH SOME LIGHT SNOW FILLING IN BEHIND. CONDITIONS HAVE IMPROVED ENOUGH TO LIFT ADVISORY ALL AREAS...AND WILL LET IT GO WITH THE AFTERNOON PACKAGE.

ANTICIPATING A LULL IN THE WEATHER FOR TONIGHT AS TODAYS SYSTEM DEPARTS EAST AND UPPER TROF STILL LUMBERING INTO THE GREAT BASIN. BASE OF THE MAIN TROF PROGGED TO MAKE IT INTO NORTHERN NM BY MORNING...EJECTING SHORTWAVES INTO SOUTH CENTRAL KANSAS AT THAT TIME AS WELL. GFS STRONGER WITH THESE FEATURES...AND WHILE SEVERAL WAVES ARE SEEN OVER THE SW US IN THE WATER VAPOR...STILL DIFFICULT TO DISCERN WHICH WILL MAKE IT HERE AND WHEN. CONSENSUS SEEMS TO BE THAT BEST WINDOW FOR ACCUMULATING SNOWS IS NOW MAINLY IN THE 15Z-0Z TIMEFRAME. GUIDANCE NUMBERS FOR SNOW HAVE COME DOWN...AND NOT MUCH INSTABILITY IN THE COLUMN. BUT WITH SOME FRONTOGENESIS...POT VORT AND Q VECTOR CONVERGENCE STILL OCCURING OVER OUR AREA AT THIS TIME...WILL KEEP SOME ADVISORY ACCUMULATIONS IN THE FORECAST FOR MUCH OF THE CWA. FAR SE COUNTIES WHERE WARNING IS IN EFFECT HAVE ALREADY SEEN OVER AN INCH OF SLEET IN PLACES...AND WILL BE EXACERBATED BY SOME SNOW ACCUMULATION ON TOP OF THIS TOMORROW. WITH PWS AROUND HALF AN INCH AND SNOW RATIOS LIKELY OVER 10/1 IN THE COLD AIR...AM NOT READY TO DROP THE WATCH JUST YET...AND WILL TREND GRIDS TOWARDS ADVISORY NUMBERS.

MAIN UPPER LEVEL WAVE FINALLY EJECTS OUT THROUGH THE PLAINS AND EXITS TO THE NORTHEAST OF THE CWA BY 12Z MONDAY...BUT NOT BEFORE PRODUCING SOME LIGHT SNOW ACROSS THE CWA...MAINLY DURING THE EVENING ALONG AND NORTH OF I-70 AS DRIER AIR AND SUBSIDENCE INCREASE FROM THE SOUTHWEST. ADDITIONAL AMOUNTS GENERALLY SHOULD BE FROM LESS THAN HALF AN INCH SOUTH TO AN INCH TO AN INCH AND A HALF NORTHEAST CORNER OF THE CWA. ALTHOUGH LOWS SUNDAY NIGHT WILL BE COLDER...CLOUDS AND INCREASING WINDS WILL KEEP TEMPERATURES FROM FALLING AS MUCH AS THEY OTHERWISE WOULD...SO WILL KEEP GENERALLY IN THE 5 TO 12 DEGREE RANGE. THE STRATUS ON MONDAY WILL THEN LINGER IN THE MORNING BUT START TO BREAK UP BY AFTERNOON. STILL...WITH EXPECTED SNOW/ICE COVER...THIS WILL LIMIT HIGHS TO THE TEENS.

TUESDAY NIGHT SHOULD BE THE COLDEST NIGHT WITH DIMINISHING WINDS...DECREASING CLOUDS AND SNOW/ICE COVER. WILL GO WITH MOST TEMPS NEAR ZERO FOR NOW...BUT DEPENDING ON SNOW/ICE DEPTHS...COULD SEE TEMPS A FEW DEGREES COLDER. ALTHOUGH SUNSHINE SHOULD BE THE RULE ON TUESDAY...MIXING WILL BE WEAK FOLLOWING VERY COLD MORNING LOWS...SO THIS WILL LIMIT HIGHS TO UPPER TEENS TO LOWER 20S. RETURN FLOW ON THE BACK SIDE OF THE HIGH SHOULD THEN KEEP LOWS ABOVE ZERO INTO WEDNESDAY MORNING WITH MOST HIGHS IN THE MIDDLE TO UPPER 20S. WILL KEEP THE REST OF THE FCST DRY ON THROUGH EARLY NEXT WEEKEND AS THE GFS/ECMWF SEEMS TOO PROGRESSIVE AND TOO FAR EAST WITH CUTOFF LOW COMING OUT OF THE SOUTHWEST U.S. WEDNESDAY. ALSO LOW CONFIDENCE WITH THE ARRIVAL TIME OF THE NEXT SYSTEM BY SATURDAY.

EITHER WAY...WITH THE SNOW/ICE COVER WILL SEE A "GRADUAL" MODERATION IN TEMPS THROUGH THE REST OF THE WEEK INTO THE 30S THURSDAY AND FRIDAY AND SOME LOWER 40S SOUTHERN CWA BY NEXT WEEKEND.

&&

.TOP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING THROUGH 06Z MONDAY FOR COFFEY...FRANKLIN AND ANDERSON COUNTIES.

WINTER STORM WATCH 12Z SUNDAY TO 06Z MONDAY FOR THE REMAINDER OF THE CWA ALONG AND NORTHWEST OF INTERSTATE 35.

&&

$$


AREA FORECAST DISCUSSION
NWS WICHITA KS
AFDICT 811 PM CST SAT JAN 13 2007

.UPDATE... HAVE CONTINUED TO TREND POPS DOWN FOR MUCH OF THE NIGHT...AS WE WILL BE IN A LULL UNTIL MAIN UPPER TROF EJECTS NORTHEAST ON SUNDAY. THAT SAID...WILL CONTINUE TO SHOW RAPID INCREASE IN POPS AGAIN BY 12Z ACROSS PORTIONS OF CENTRAL AND SOUTH CENTRAL KANSAS AS PREVIOUS FORECASTER HAD SHOWN IN GRIDS/FORECAST. NOT MUCH IN THE WAY OF WEATHER PROBLEMS FROM ANY PRECIPITATION OVERNIGHT...THOUGH THE WAY HAS BEEN PAVED TO STAY WITH THE WINTER STORM WARNING TO AVOID CONFUSION...WITH MODEST EXPECTATIONS TO REALIZE CRITERIA ON SUNDAY IN LAST 12 HOURS OF VALID TIME. OTHERWISE...ONLY SLIGHT TWEAKS TO TEMPERATURES/WINDS FOR TONIGHT.

KED

&&

.PREV DISCUSSION... /ISSUED 253 PM CST SAT JAN 13 2007/

SYNOPSIS...

SIGNIFICANT CONCERNS OVER VALIDITY OF LATEST MODEL RUNS. OF PARTICULAR NOTE IS DEARTH OF OBSERVATIONAL DATA ACROSS SOUTHWESTERN US...ESPECIALLY SOUTHERN NEVADA/NORTHWEST AZ/UT. ACARS DATA AROUND 1200 UTC IS EVEN LACKING. GIVEN MOST PRECIPITATION HAS BEEN DRIVEN BY WEAKER RIPPLES OVER HIGHLY BAROCLINIC LOW LEVELS... CONFIDENCE IS GOING TO BE LOW. ALSO OF NOTE...WATER VAPOR LOOP SUGGEST DECENT AMOUNT OF ENERGY ABOUT TO ROUND THE CLOUD BASE OF LONG WAVE TROUGH WELL OFF GULF OF CA. HOW WELL THIS WILL BE HANDLED IS ALSO SUSPECT. ON THE PLUS SIDE...LATEST RUNS SOMEWHAT SIMILAR TO YESTERDAYS RUNS...WHICH AT LEAST MEANS NO BIG CHANGES FROM PREVIOUS THINKING.

DISCUSSION...

TONIGHT-SUN:

PLAN TO KEEP HEADLINES GOING...ALTHOUGH MAKING CRITERIA MAY BE MARGINAL. FORCING WILL BE ON THE WANE TONIGHT ONCE CURRENT BATCH OF PRECIPITATION EAST OF I-35 MOVES OUT...WITH LIGHT PRECIPITATION ANTICIPATED FOR REMAINDER OF THE NIGHT. PRECIPITATION TYPE WILL LIKELY BE SOME COMBO OF LIGHT SNOW/LIGHT ICE PELLETS/LIGHT FREEZING DRIZZLE. NEXT SIGNIFICANT SHORTWAVE WILL ENTER SOUTHWEST CORNER OF FORECAST AREA AROUND 1200 UTC...AND SPREAD NE DURING THE DAY. MAIN CONCERN IS AREA WEST OF A LINE FROM KINGMAN TO MCPHERSON...WHERE MARGINALLY DECENT LAPSE RATES AND PERSISTENCE OF LIFT WILL BE MAXIMIZED. 1200 UTC RUNS CONTINUE TO FORECAST A COUPLED UPPER JET SO WILL ALSO BE DECENT UPPER SUPPORT. JUST NOT ENOUGH CONFIDENCE IN LAPSE RATES AND LIFT TO REALLY JUMP ON SNOW AMOUNTS...ESPECIALLY IF FAIR AMOUNT OF THE PRECIPITATION IS SLEET. MINIMUM WILL LIKELY BE AROUND ICT AND AREAS IMMEDIATELY SOUTH. IN SOUTHEAST KS PRECIPITATION WILL START LATE MORNING AND PERSIST INTO THE EVENING. AGAIN SLIGHTLY LONGER PERSISTENCE WILL ADD ACCUMULATION. WITH THERMAL PROFILE NOT EXPECTED TO CHANGE SIGNIFICANTLY...EXPECT A COMBO OF TYPE THERE AS WELL.

SUN NIGHT-MON:

PRECIPITATION WILL MOST LIKELY BE ON THE WANE BY MIDNIGHT. CAVEAT MAY BE IF LAGGING UPPER WAVE DOES SLOW OVERALL PROGRESSION DOWN... PRECIPITATION MAY LINGER INTO MON. GOING CONSENSUS WAS TO NIX PRECIPITATION.

TUE-SAT:

EARLY IN THIS PERIOD MAIN CONCERN WILL BE COLD TEMPERATURES WITH GOOD DIURNAL COOLING FOLLOWED BY MODERATING TEMPERATURES WITH ARCTIC AIRMASS OVER THE AREA. HOW LONG/HOW PRONOUNCED THESE IMPACTS WILL BE WILL BE HIGHLY DEPENDENT ON WHAT OCCURS IN THE NEXT 24-36 HOURS. LATER IN THE PERIOD...GIVEN HIGH LEVEL OF UNCERTAINTY WITH ONGOING PATTERN CHANGE AND ANOTHER PATTERN CHANGE IN THE OFFING FOR LATE IN THE WEEK...OPTED NOT TO INTRO PRECIPITATION CHANCES JUST YET ON DAY 7. AT FACE VALUE...BOTH 0600 UTC GLOBAL FORECAST SYSTEM MODEL/00 UTC EUROPEAN CENTRE FOR MEDIUM RANGE WEATHER FORECASTS MODEL WOULD SUGGEST SOME OVERRUNNING PRECIPITATION NORTH OF FRONTAL BOUNDARY WHICH WOULD MOVE THROUGH THE AREA THU AFTERNOON PER GLOBAL FORECAST SYSTEM MODEL OR LATE FRI AFTERNOON OR EVENING PER EUROPEAN CENTRE FOR MEDIUM RANGE WEATHER FORECASTS MODEL. THE LATTER IS 12 HOUR EARLIER THAN PREVIOUS RUN. DEPTH...TIMING AND ORIENTATION OF LONGWAVE TROUGH OVER WESTERN US ARE STILL UNCERTAIN AS WELL. AT THIS POINT...DOES NOT APPEAR TO BE A MAJOR SURFACE CYCLONE IN THE OFFING WITH THIS UPPER SYSTEM...SO PRECIPITATION WILL BE DEPENDENT ON SUBTLE ORIENTATION OF WINDS AND THERMAL GRADIENT. -HOWERTON

&&

.PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 13 16 10 19 / 40 100 30 10 HUTCHINSON 11 15 9 18 / 40 100 40 10 NEWTON 12 16 9 18 / 30 100 40 10 ELDORADO 12 17 10 19 / 40 100 40 10 WINFIELD-KWLD 15 19 11 20 / 50 100 20 0 RUSSELL 10 15 7 16 / 40 100 60 10 GREAT BEND 11 15 8 16 / 50 100 50 10 SALINA 11 15 8 17 / 30 100 60 10 MCPHERSON 11 15 9 17 / 30 100 50 10 COFFEYVILLE 18 23 14 22 / 60 100 30 10 CHANUTE 16 21 13 21 / 60 100 30 10 IOLA 15 20 13 20 / 60 100 30 10 PARSONS-KPPF 17 22 14 22 / 60 100 30 10

&&

.ICT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR KSZ032-033- 047>053-067>072-082-083-091>096-098>100.

&&

$$


AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
AFDLMK 230 AM EST FRI JAN 12 2006

.SHORT TERM (TODAY AND TONIGHT)...

EARLY MORNING ACARS SOUNDINGS FROM SDF INDICATED THE ATMOSPHERE WAS STILL FAIRLY DRY BELOW 700MB. SURFACE DEPRESSIONS AT 07Z WERE ALSO AROUND 20 DEGREES. WE WILL NEED TO SATURATE THIS LAYER BEFORE SIGNIFICANT RAIN BEGINS TO FALL.

IN THE UPPER LEVELS OF THE ATMOSPHERE A WEST COAST TROUGH WILL CONTINUE TO DEEPEN WITH RIDGING ACROSS THE EASTERN UNITED STATES. A 100KT JET WILL DEVELOP JUST TO THE NORTH OF THE REGION LATE IN THE DAY AND WILL AID IN PRECIPITATION GENERATION OVERNIGHT. AT THE SURFACE A VERY WELL DEFINED COLD FRONT EXTENDED FROM SOUTHEAST KANSAS TO NORTHWEST ILLINOIS AT 06Z. TEMPERATURES ACROSS THE FRONT WERE 15 TO 20 DEGREES WITH VERY COLD AIR IN THE TEENS NOTED IN IOWA.

NOT MUCH TO GET A HANDLE ON THIS MORNING WITH LACK OF LIFT WE EXPECT MAINLY AREAS OF LIGHT TO OCCASIONALLY MODERATE RAIN ACROSS THE FORECAST AREA. THE BEST CHANCE FOR HEAVY RAIN WILL OCCUR TONIGHT AND MAINLY ACROSS SOUTHERN INDIANA. THE LIFT FROM THE FORE MENTIONED JET COMBINED WITH A DEVELOPING WAVE ALONG THE COLD FRONT WILL BRING HEAVY RAIN TO THE REGION BETWEEN 06Z AND 12Z SATURDAY. WIDESPREAD 1 INCH AMOUNTS WILL BE COMMON ACROSS SOUTHERN INDIANA WITH LESSER AMOUNTS ACROSS CENTRAL KENTUCKY.

WITH THE MOIST SOUTHERLY FLOW IN PLACE WE WILL NOT SEE MUCH DIURNAL TEMPERATURE CHANCE THROUGH THE PERIOD WITH TEMPERATURES REMAINING IN THE 50S. --JA

LONG TERM (SATURDAY THROUGH THURSDAY)...

OCCASIONAL RAIN FROM SATURDAY THROUGH EARLY MONDAY WILL LEAD TO SUBSTANTIAL RAINFALL TOTALS AND A THREAT OF FLOODING EARLY NEXT WEEK.

UPPER AIR PATTERN WILL FEATURE A SHEARED POSITIVELY TILTED TROUGH WHOSE CENTER WILL ONLY SLOWLY MOVE FROM NEVADA TO COLORADO THROUGH LATE SUNDAY. STRONG SOUTHWESTERLY MID LEVEL FLOW WILL CONTINUE ACROSS THE MID PART OF THE COUNTRY AND WILL EFFICIENTLY TRANSPORT MOISTURE TOWARDS THE LOWER MISSOURI AND OHIO VALLEYS. ARCTIC HIGH PRESSURE ACROSS THE NORTHERN PLAINS WILL HELP PUSH A SHALLOW COLD FRONT TOWARDS THE OHIO RIVER EARLY SATURDAY. THIS FRONT WILL SERVE AS A FOCUS FOR REPEATED EPISODES OF RAIN AS IT SLOWLY MOVE TOWARDS CENTRAL KENTUCKY...AND THEN STALLS SUNDAY.

TIMING INDIVIDUAL DISTURBANCES AND CORRESPONDING PERIODS OF HEAVIER RAIN WILL BE CHALLENGING AS THE UPPER FLOW WILL BE BROAD...AND NO OBVIOUS DISTURBANCES WILL MOVE NORTHEAST THROUGH THE FLOW UNTIL THE UPPER TROUGH EJECTS INTO THE PLAINS LATE SUNDAY.

THE NAM MODEL HINTS AT WEAK LOW PRESSURE MOVING JUST NORTH OF THE OHIO RIVER EARLY SATURDAY ALONG A SURFACE BOUNDARY. BOTH GFS AND NAM FORECAST HIGHER RAINFALL AMOUNTS DEVELOPING ACROSS SOUTHERN INDIANA FRIDAY NIGHT AND SAGGING SOUTHEAST INTO CENTRAL KENTUCKY BY LATE SATURDAY.

ANOTHER PERIOD OF MODERATE TO OCCASIONALLY HEAVY RAIN IS FORECAST TO DEVELOP LATE SUNDAY AND CONTINUE THROUGH MID DAY MONDAY AS THE UPPER TROUGH ACROSS THE SOUTHERN PLAINS OPENS UP AND MOVES TOWARDS IOWA. LOW PRESSURE WILL DEVELOP ALONG THE BY NOW STATIONARY FRONT AND MOVE ACROSS CENTRAL OR NORTHERN KENTUCKY DURING THE EARLY MORNING HOURS MONDAY. THE AXIS OF HEAVY RAIN IS EXPECTED TO DEVELOP RIGHT ALONG THE BOUNDARY AND THE EVENTUAL PATH OF THE SURFACE LOW.

THE GFS IS MUCH WETTER IN QPF AMOUNTS THEN THE NAM AND WILL FORECAST AN AMOUNT IN BETWEEN THE TWO. FOR THE ENTIRE WEEKEND PERIOD INTO MONDAY...STILL FEEL THAT 2 TO 4 INCHES WITH LOCALLY HIGHER AMOUNTS ARE LIKELY...WITH THE BULK OF THIS FALLING LATE SUNDAY INTO MONDAY. WILL CONTINUE FLOOD WATCH FROM LATE FRIDAY THROUGH EARLY MONDAY.

TEMPERATURES WILL BE A CHALLENGE BOTH SATURDAY AFTERNOON AND SUNDAY. THE NAM IS SIMILAR TO YESTERDAY WITH BEING ONCE AGAIN LESS AGGRESSIVE WITH THE SOUTHEASTWARD PUSH OF THE FRONT...STALLING IT OUT JUST SOUTH OF THE OHIO RIVER EARLY SUNDAY. THE GFS PUSHES THE FRONT FARTHER SOUTH INTO NORTHWESTERN TENNESSEE BY THIS SAME TIME. THIS BOUNDARY MAY KEEP TEMPERATURES ACROSS SOUTHERN INDIANA IN THE MID 40S SUNDAY...WHILE 60 MAY BE APPROACHED ALONG OUR SOUTHERN COUNTIES.

MONDAY THROUGH TUESDAY...

SURFACE LOW WILL RAPIDLY MOVE OFF TO OUR EAST MONDAY AND DEEP LAYER MOISTURE WILL MOVE SOUTH ALONG SURFACE BOUNDARY INTO THE TENNESSEE VALLEY. AS HIGH PRESSURE BUILDS ACROSS THE UPPER MIDWEST...COLDER AIR WILL FILTER ACROSS OUR AREA MONDAY AND TUESDAY. THIS WILL KNOCK OUR TEMPERATURES DOWN TO SEASONABLE LEVELS. FORECAST SOUNDINGS SHOW AMPLE LOW LEVEL MOISTURE LINGERING SEVERAL HUNDRED MILES NORTH OF THE COLD FRONT...SO EXPECT CLOUDY SKIES TO CONTINUE PROBABLY INTO EARLY TUESDAY.

TUESDAY NIGHT THROUGH THURSDAY...

HIGH PRESSURE WILL BUILD INTO THE AREA TUESDAY AND KEEP DRY BUT COLD WEATHER OVER THE LOWER OHIO VALLEY THROUGH THURSDAY.

JSD

&&

.LMK WATCHES/WARNINGS/ADVISORIES... KY...FLOOD WATCH FROM FRIDAY EVENING THROUGH LATE SUNDAY NIGHT FOR KYZ023>043-045>049-053>057-061>067-070>078-081-082.

IN...FLOOD WATCH FROM FRIDAY EVENING THROUGH LATE SUNDAY NIGHT FOR INZ076>079-083-084-089>092.

&&


TERM FORECAST DISCUSSING THIS SCENARIO. PRECIPITATION TOTALS
UPSTREAM HAVE BEEN ON THE OTHER OF SEVERAL HUNDREDTHS OF AN INCH OR
AFDLWX LESS.

FRONTAL BOUNDARY ACROSS THE CENTRAL CONUS WILL SHARPEN UP AS THE ROCKIES POSITIVELY TILTED TROUGH AXIS EASES EAST. THIS WILL SET UP A CORRIDOR OF PRECIPITATION AS COPIOUS MOIST INFLUX FROM THE WESTERN GULF OVERRUNS THE BOUNDARY ACROSS THE PLAINS. SOUTHWESTERLY DEEP LAYER FLOW WILL AID IN PRECIPITATION DEVELOPING NORTHEAST THROUGH THE OHIO VALLEY AND EASTERN GREAT LAKES. THIS IS AN ANNAFRONTAL SYNOPTIC SETUP...WITH MUCH OF THE PRECIPITATION ALONG AND BEHIND THE BOUNDARY. THEREFORE...NOT EXPECTING MUCH MORE THAN A FEW LIGHT RAIN SHOWERS DURING THE SHORT TERM WITHIN THE WARM SECTOR.

WITH EXTENSIVE CLOUD COVER...THOUGHT MOS HIGHS MAY HAVE BEEN A FEW DEGREES TOO OPTIMISTIC. SIMILARLY...THEY MAY BE TOO COOL TONIGHT. LOW TEMPERATURES MAY NEED TO BE NUDGED EVEN HIGHER. PRESSURE GRADIENT ON THE BACKSIDE OF THE SURFACE HIGH WILL SUPPORT SOUTHWEST FLOW THROUGH THE SHORT TERM PERIOD.

AVIATION... CONTINUED WARM ADVECTION WILL ALLOW CLOUDS TO BUILD DOWN THROUGH THE TAF CYCLE. EXPECT WARM ADVECTION PRECIPITATION CLIPPING THE WEST VIRGINIA PAN HANDLE TO BE IT THIS MORNING...WITH REMAINING PRECIPITATION LARGELY ALONG AND BEHIND THE OHIO VALLEY FRONTAL BOUNDARY THROUGH TONIGHT.

MARINE... 00Z ETA MOS AT THOMAS POINT SUGGESTS 16KT SUSTAINED TODAY...AND 10KT TONIGHT...WHILE THE 00Z GFS MOS SHOWS 10KT THROUGH THE SHORT TERM. 00Z NAM PROXIMITY LAND BUFKIT FORECAST SOUNDINGS SUGGEST ADDITIONAL WIND GUST MOMENTUM OF UP TO 20 KNOTS POSSIBLE NEAR THE VIRGINIA STATE LINE AND ALONG THE POTOMAC TODAY...WHILE THE 00Z GFS ALSO INDICATES 20KT WIND GUSTS NEAR THE VIRGINIA WATERS. WILL THEREFORE HAVE A SMALL CRAFT ADVISORY ACROSS THE POTOMAC/BAY MARINE ZONES CLOSEST TO THE VIRGINIA STATE LINE.

POSITIONING OF BNDRY ON SUN WILL CONTROL THE THREAT OF STRONGER WINDS OVER THE MARINE AREA AS PRES GRAD SHOULD REALLY GET GOING BY SUNDAY NIGHT AS LOW PRES MOVES FROM THE OH VLY. THINK BEST CHC WILL BE ON MONDAY ACROSS THE SOUTHERN MARINE ZONES FOR SCA WINDS...THEN ALL ZONES ON TUESDAY ONCE NW FLOW KICKS UP.

TIDES... WATER LEVELS ARE CURRENTLY A FOOT ABOVE ASTRONOMIC PREDICTIONS. THE LUNAR CYCLE IS WANING (43% FULL). A LONG DURATION SOUTHWEST FLOW WILL CONTINUE AHEAD OF A SLOW MOVING COLD FRONT. THIS WILL PROMOTE RISING WATER LEVELS WHICH NEED TO BE MONITORED SHOULD THEY BEGIN TO NEAR MINOR COASTAL FLOOD CRITERIA.

THE CHESAPEAKE BAY OPERATIONAL FORECAST SYSTEM HAS SLIGHTLY UNDER-PREDICTED WATER LEVELS THUS FAR...AND MAINTAINS CURRENT DEPARTURES THROUGH THE AFTERNOON. THE NOAA EXTRATROPICAL STORM SURGE MODEL DID NOT THE CAPTURE DEPARTURE RISES.

LONG TERM...SATURDAY THROUGH THURSDAY...

BNDRY WILL SETTLE ACROSS OUR FORECAST AREA BETWEEN SATURDAY AND SUNDAY AND HELP TO FEED WAVES OF SHOWERS ACROSS THE REGION. MOS POPS VARY QUITE A BIT BETWEEN NW AND SE ZONES BUT HAVE INDICATE LESS EXTREME DELINEATIONS SINCE EXACT FRONTAL PLACEMENT AND SUBSEQUENT PRECIP AREAS STILL A LITTLE DIFFICULT TO PINPOINT. BOTH DAYS WILL HAVE 50-70 POPS ACROSS THE AREA. ONLY MIDDLE RANGE CHC POPS FOR SAT NGT THOUGH AS THERE SHOULD BE A BRIEF RESPITE FROM THE WEAK LOW PRES WAVE ACTION ALONG THE BNDRY. SUN NGT AND MON WILL CONTINUE TO INDICATE FAIRLY GOOD CHCS FOR RAINFALL AS ADDITIONAL LOW PRES WAVES FORM ALONG THE FRONT...AND THE FRONT BEGINS TO KICK THROUGH ON MONDAY OR MONDAY EVNG WITH A REALLY DECENT PUSH OF ARCTIC FROM ACROSS THE OHIO VALLEY.

DURING THE TUESDAY THROUGH THURSDAY TIMEFRAME...COLD AIRMASS SETTLES OVER OUR REGION ALTHOUGH THERE PROBABLY WON`T BE ANY DECENT PRECIP MAKERS SAVE FOR A FEW SNOW SHOWERS IN THE HIGHER TERRAIN GIVEN THE COLD NW FLOW AND SOME U/L VORT ENERGY. BEST CHC OF COURSE LATE MON NGT AND TUESDAY ACROSS THE ALLEGHENY FRONT WHEN SOME DECENT UPSLOPE SNOW SHWRS COULD TAKE PLACE. TEMPS NEAR OR SLIGHTLY BELOW NORMAL TUE-THU WITH HIGHS IN THE 30S AND LOWS IN THE TEENS.

&&

.LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR ANZ532>534-537.

&&

$$

SHORT TERM/AVIATION/MARINE UPDATE...SAR PREV DISCUSSION...ROGOWSKI/JB


AREA FORECAST DISCUSSION
NWS GREEN BAY WI
AFDGRB 1245 PM CST FRI JAN 12 2007

.UPDATED AT 1245 PM...JET STREAK PRODUCING ENOUGH LIFT TO SQUEEZE OUT SOME FREEZING DRIZZLE AND SNOW FLURRIES IN THE SOUTHEAST THIRD OF THE FORECAST AREA. THIS SHOULD CONTINUE INTO THE EARLY EVENING. GROUND TEMPERATURES ARE WARM...SO NOT SURE WHETHER WE WILL GET ICING ON ROADS OR NOT. IF WE START GETTING ICING REPORTS WE MAY ISSUE A WINTER WEATHER ADVISORY.

.SHORT TERM...TODAY THROUGH SATURDAY. FLAT RIDGE OVER SOUTHEASTERN U.S. WITH POS TILTED TROF EXTENDING FROM HUDSON BAY TO THE GREAT BASIN. AT THE SURFACE...FRONT NOW OVER SOUTHEAST PORTION OF CWA...MOVEMENT SLOWER THAN MODELS INDICATED IN PREVIOUS RUNS. HIGH PRESSURE BUILDING IN FROM THE NORTHERN PLAINS WITH VERY COLD AND DRY AIRMASS. WIDESPREAD LOW CLOUDS OVER STATE ATTM WITH SATELLITE INDICATING SOME CLEARING OVER FAR WESTERN WI. NOT MAKING GREAT HEADWAY EAST AT THIS TIME. MID AND HIGH CLOUDS LIFTING NORTH THROUGH NORTHWEST WI ASSOCIATED WITH JET PULLING INTO SOUTHERN CANADA. SOME LIGHT RETURNS SEEN ON AREA RADARS THIS AREA...THOUGH NOTHING SEEN AT SURFACE.

THIS PERIOD TO REMAIN RATHER QUIET WITH HIGH PRESSURE OVER THE AREA. FORECAST CONCERNS CENTER ON CLOUD FORECAST. MODEL CROSS SECTIONS INDICATE LOW CLOUDS HANGING TOUGH THROUGH TODAY...SOME DRYING FROM THE NORTH LATER TONIGHT INTO SATURDAY. WILL STAY WITH MOSTLY CLOUDY FORECAST TODAY...THEN DIMINISH CLOUDS THROUGH SAT NORTH AND WEST AS HIGH WORKS IN. SOUTHERN PORTION OF CWA EXPECTED TO SEE MORE IN THE WAY OF MID AND HIGH CLOUDS AS WAVES RIDE NORTHEAST ALONG BAROCLINIC ZONE TO THE SOUTH OF STATE. STRONG CAA TODAY WILL ALLOW FOR FALLING TEMPS THROUGH THE DAY.

OTHER CONCERN THIS PERIOD IS SMALL CHANCE OF LAKE EFFECT THIS AFTERNOON INTO TONIGHT OVER NORTH CENTRAL. HAVE BACKED OFF ON COVERAGE AND POPS A BIT. LOW LEVEL WINDS NEVER IDEAL WITH TOO MUCH SHEAR IN THE LOWER LEVELS...THEN BACK WEST BY SAT AM.

AVIATION...UPDATED AT 1245 PM. TAMDAR SOUNDINGS FROM CWA AND ATW SHOW LOTS OF MOISTURE BELOW 800 MB BUT DRY ABOVE. TEMPERATURES ALL ABOVE - 10C...SO NOT MUCH CHANCE OF SNOW JUST FZDZ. CEILINGS SHOULD SLOWLY CLIMB DURING LATE AFTERNOON AND EVENING.

.LONG TERM...SAT NGT THRU NXT THU. MAIN FCST FOCUS CENTERS AROUND POTENTIAL FOR SNOW ACROSS NE WI THIS WEEKEND INTO EARLY NXT WEEK. WL ALSO HAVE TO DEAL WITH TEMPS THEREAFTER AND THE DEPTH OF THE COLD AIR INTRUSION.

AS THE UPR TROF DIGS TOWARD THE FOUR CORNERS RGN SAT NGT...A LEAD SHRTWV IS PROGGED TO LIFT NE INTO THE MIDWEST. WHILE BETTER FORCING WL REMAIN TO OUR SOUTH...CANNOT RULE OUT THAT THE NRN EDGE OF ANY PCPN WOULD APPROACH SRN SECTIONS OF THE FCST AREA. PREFER TO ADD A SLGT CHC OF LGT SNOW GENERALLY SOUTH OF A ISW-SUE LINE. OTHERWISE...PLENTY OF CLDS EXPECTED OVR THE REST OF NE WI WITH MIN TEMPS IN THE SINGLE DIGITS AND TEENS. THE INITIAL SHRTWV AND ASSOCIATED FORCING SHIFT EAST BY SUNDAY. AS THE UPR TROF PUSHES TOWARD THE CNTRL/SRN PLAINS AND CANADIAN HI PRES DROPS SOUTH INTO THE NRN PLAINS...SFC WNDS ARE EXPECTED TO VEER MORE N-NE DURING THE DAY. 8H TEMPS RESIDING AROUND -14C OVR NRN LK MI AND -20C OVR WRN LK SUPERIOR MAY ALLOW FOR SOME SNOW SHWRS TO MOV INTO EXTREME ERN WI/NRN WI. EXACT WND DIR WL BE KEY WHETHER ANY SNOW SHWRS AFFECT KEWAUNEE/MANITOWOC COUNTIES OR REMAIN OFFSHORE. PREFER TO GO DRY ESLEWHERE AS THERE IS NO OTHER TRIGGER PRESENT.

UPR TROF IS PROGGED TO MOV INTO THE CNTRL PLAINS SUNDAY NGT WITH THE SFC LOW TO TRACK FROM THE OZARKS NEWD INTO THE OHIO RIVER VALLEY. IF THIS SCENARIO PLAYS OUT THIS WAY...THE HEAVIER SNOW WOULD STAY TO OUR SOUTH AND EAST WITH OUR SNOW MORE OF A RESULT OF THE DEFORMATION ZN. HIGHEST POPS TO REMAIN OVR THE SRN TIER OF COUNTIES WITH A SHARP CUT-OFF TO ONLY SLGT CHC POPS FOR THE NRN HALF OF THE FCST AREA. APRS NOW THAT NOTHING MORE THAN AN INCH OR TWO PSBL SUNDAY NGT. INITIAL UPR TROF PUSHES INTO THE GREAT LKS RGN ON MON AS ANOTHER UPR TROF DIGS TOWARD THE DESERT SW. LINGERING CHCS OF LGT SNOW EXPECTED OVR CNTRL/E-CNTRL WI...WITH THE POTENTIAL OF ADDL LK EFFECT SNOW SHWRS ADDING SOME MINOR ACCUMULATIONS TO THE LKSHR COUNTIES. WL CONT THE LIKELY WORDING FOR DOOR...KEWAUNEE... AND MANITOWOC COUNTIES. WL HAVE TO WATCH TEMPS AS LACK OF NEW SNOW MAY ALLOW TEMPS TO WARM MORE THAN PREVIOUSLY THOUGHT.

NORTHERLY WNDS TO PERSIST RIGHT INTO TUE AS HI PRES BEGINS TO BUILD EAST TOWARD THE WRN GREAT LKS. TRAJS WOULD CONT TO FAVOR A CHC OF LK EFFECT SNOW SHWRS OVR VILAS CNTY WHILE AREAS NEAR LK MI APR TO BE ON THE FRINGES OF SNOW SHWRS MOVG SOUTH OVR LK MI. PREFER TO ADD FLURRIES RIGHT ALONG THE SHORELINE AS TRAJS SEEM TOO MUCH DUR NORTH TO BRING SNOW INLAND. HAVE NUDGED TEMPS UP A DEG OR TWO BASED AGAIN ON THE LACK OF FRESH SNOW. HI PRES TO BE SITUATED OVR THE RGN ON WED USHERING IN DRIER AIR AND BACKING WNDS. ANY LK EFFECT SNOW WOULD END...THUS HAVE KEPT DRY CONDITIONS GOING FOR NE WI WED. COLDEST OF THE AIRMASS TO START SHIFTING EWD BY WED SO AN UPTICK IN TEMPS SHOULD BEGIN.

SPLIT FLOW TO RETURN BY THE MIDDLE OF NXT WEEK WITH MDLS HINTING AT A NRN STREAM SYSTEM TO DROP SE INTO THE GREAT LKS NXT THU. TIMING ISSUES COME INTO PLAY HERE SO HAVE LEFT THU DRY FOR NOW. IF SUCCESSIVE MDL RUNS CONT TO SHOW THIS SYSTEM MOVG IN...POPS WOULD NEED TO BE ADDED.

&&

.GRB WATCHES/WARNINGS/ADVISORIES... NONE &&

$$ RDM/ECKBERG WEATHER.GOV/GREENBAY


AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
AFDIWX 146 AM EST SUN JAN 14 2007

.AVIATION... PATCHY FREEZING DRIZZLE WILL PERSIST THIS MORNING WITH AREAS OF FREEZING RAIN DEVELOPING AS A WEAK UPPER LEVEL SYSTEM MOVES INTO THE AREA. EXPECT ONLY A SLIGHT TEMPERATURE INCREASE TODAY...BUT JUST ENOUGH FOR FWA TO RISE ABOVE FREEZING. HAVE KEPT SBN AT OR BELOW FREEZING...SO HAVE INCLUDED FREEZING DRIZZLE AND FREEZING RAIN THERE. NOT MUCH OF A CHANCE FOR CIGS TO IMPROVE OUT OF THE IFR CATEGORY AS THE FRONT REMAINS SOUTH OF THE AREA AND AS MOISTURE CONTINUES TO SPREAD NORTH OVER THE FRONT.

&&

.UPDATE... UPDATED ZONES/GRIDS TO ADD MENTION OF PRECIP THIS EVE. HAVE SEEN A COUPLE WAVES OF DRIZZLE MOVE THROUGH THE AREA LATE THIS AFTN AND THIS EVE AS WK TROFS MOVG THROUGH THE FLOW PROVIDING SLIGHT ENHANCEMENT TO THE GENERAL OVER-RUNNING PATTERN IN PLACE. MORE SGFNT PRECIP OVER WEST CENTRAL IL HAS BEEN DIMINISHING AS IT MOVES NE THIS EVE AND 00Z SOUNDINGS ARE SHOWING SOME MID LEVEL DRYING HAS OCCURRED TODAY OVER OUR AREA. 00Z NAM SUGGESTS DEEPER MOISTURE AND PRECIP ASSOCIATED WITH SHRTWV SEEN ON WATER VAPOR LOOP MOVG THROUGH MO MAY NOT REACH US UNTIL CLOSE TO DAYBREAK. HWVR, WITH A COUPLE OF WAVES OF FREEZING DRIZZLE ALREADY MOVG THROUGH THE AREA, THINK IT`S LIKELY THAT MORE OF THIS LIGHT FREEZING PRECIP WILL OCCUR OVERNIGHT SO WILL HOLD ONTO THE ADVISORY ISSUED EARLIER FOR LATE TONIGHT AND SUNDAY, THOUGH ATTM APPEARS THE MOST SGFNT PRECIP DURING THIS ADVISORY MAY HOLD OFF UNTIL SUNDAY MORNING.

&&

.SHORT TERM... TONIGHT AND SUNDAY

WILL SIDE MORE WITH THE 12Z NAM-WRF THAN THE 12Z GFS FOR THIS FORECAST PACKAGE. THE THERMAL PROFILES SEEM MORE PLAUSIBLE THAN THE GFS AS SEEN BY MOST CURRENT TAMDAR DATA.

AT 19Z...SFC ANALYSIS DEPICTED A NEARLY STATIONARY FRONTAL BOUNDARY NEAR THE OHIO RIVER. THIS FRONT WILL UNDULATE SOME OVER THE NEXT 24 HOURS AS WAVES OF SFC LOW PRESSURE RIPPLE NE ALONG IT. MEANWHILE...ARCTIC HIGH PRESSURE WAS SPRAWLED FROM ONTARIO WESTWARD INTO THE UPR MS RIVER VLY. COLDER AIR HAS MADE ITS WAY INTO THE NRN THIRD OF THE FCST VIA SFC NE FLOW. THE FORECAST DILEMMA FOR TONIGHT INTO SUNDAY WILL BE HOW FAR SOUTH THE FREEZING LINE WILL MOVE AND HOW THIS WILL AFFECT PCPN TYPE.

FOR TONIGHT...A TANDEM OF UPR LVL S/WVS WILL ROTATE NE INTO THE WRN GREAT LAKES AND OHIO VLY REGION FROM THE SRN PLAINS/LOWER MS RIVER VLY. THESE S/WVS WILL PROVIDE UPR SUPPORT FOR VERTICAL LIFT. IN ADDITION...MODELS INDICATE THAT WARM...MOIST ISENTROPIC LIFT WILL DEVELOP TONIGHT...CONTINUING INTO SUNDAY. THE COMBINATION OF THE LIFT FROM THE S/WVS AND THE LIFT FROM MOIST...WARM AIR ADVECTION WILL CAUSE PCPN TO BREAK OUT FROM W TO EAST OVERNIGHT. WITH TEMPS AT OR BELOW FREEZING ACRS THE NRN TWO THIRDS OF THE FCST AREA AND WITH A WARM TONGUE OF AIR EXPECTED ALOFT...PCPN WILL FALL IN THE FORM OF FREEZING RAIN AND SLEET. ICE ACCUMULATIONS FROM THE FREEZING RAIN WILL BE ON THE LIGHT SIDE OVERNIGHT...MEASURING 0.05 OF AN INCH OR LESS. HOWEVER...ANY ICE WILL BE A HAZARD TO TRAVEL. HENCE...WILL ISSUE WINTER WX AND FREEZING RAIN ADVISORIES FOR TONIGHT STARING AFTER MIDNIGHT. ON SUNDAY...THERE MAY BE A BRIEF LULL IN THE PCPN BY AFTN AS AFOREMENTIONED S/WVS PIVOT OFF TO THE NE. HOWEVER...ANOTHER DISTURBANCE AND STRONGER WAVE OF LOW PRESSURE WILL APCH THE OHIO VALLEY BY EARLY EVENING...SPREADING WIDESPREAD PCPN BACK INTO THE REGION. KEEPING THIS IN MIND...HAVE DECIDED TO KEEP LIKELY POPS FOR THE ENTIRE PERIOD. TEMPERATURES WILL ONLY WARM SLIGHTLY DURING THE DAY...PERHAPS 3 TO 5 DEGREES FROM MORNING LOWS. ANY FREEZING RAIN BY AFTN WILL PROBABLY NOT ACCUMULATE MUCH WITH TEMPS HOVERING IN THE 32 TO 34 DEGREE RANGE. TO KEEP HEADLINES SOMEWHAT SIMPLISTIC WILL EXTEND THE ADVISORY THROUGH THE ENTIRE DAY AS ICING WILL LIKELY OCCUR DURING THE MORNING HOURS (ANOTHER 0.05 OF AN INCH). ALSO...THIS WILL MATCH UP WITH THE LONG TERM FORECASTER/S PLAN TO ISSUE A WINTER STORM WATCH FOR THE SUNDAY NIGHT/MONDAY TIME FRAME DUE TO THE NEXT WEATHER SYSTEM TO AFFECT THE REGION.

&&

.LONG TERM... SUNDAY NIGHT THROUGH SATURDAY

VERY CHALLENGING LONG TERM WITH THE FOCUS CONTINUING TO LIE WITH POTENTIAL MAJOR MIXED PRECIP EVENT AT THE START OF THE PERIOD. WATER VAPOR IMAGERY THIS AFTERNOON SHOWING A WELL DEVELOPED MID/UPPER LEVEL TROUGH AND EMBEDDED CLOSED CIRCULATION OVER THE WESTERN CONUS. A DEEP PLUME OF SUB-TROPICAL MOISTURE EMANATING FROM THE LOW LATITUDES OF THE PACIFIC STRETCHES INTO THE CENTRAL CONUS IN ADVANCE OF THE WESTERN TROUGH WITH PWAT SOME 2-3 STDEV ABOVE NORMAL FOR JAN. THIS WILL SET THE STAGE FOR YET ANOTHER SIGNIFICANT QPF EVENT...ONLY THIS TIME THERE WILL BE A LOW LEVEL ARCTIC AIRMASS ATTEMPTING TO UNDERCUT THE CONTINUED WARM/MOIST SW FLOW ALOFT.

SIMILAR TO MIDNIGHT SHIFT...HAVE LEANED TOWARDS THE STRONGER AND FARTHER NW SOLUTION OF THE NAM OVER THE FLATTER AND SUPPRESSED GFS SOLUTION. THE NAM HAS SUPPORT FROM BOTH THE CANADIAN REGIONAL GEM AND THE UKMET FOR THE PAST SEVERAL RUNS. ON SUNDAY SHORTWAVE ENERGY AND ASSOCIATED HEIGHT FALLS EJECTING OUT OF MEAN WESTERN CONUS TROUGH WILL SPAWN ANOTHER SURFACE WAVE ALONG THE BAROCLINIC BOUNDARY STRETCHING FROM THE SOUTHERN PLAINS INTO THE OHIO VALLEY. BOTH NAM/GFS SHOW RAPIDLY STRENGTHENING UPPER LEVEL JET ACROSS THE GREAT LAKES SUN NGT IN ADVANCE OF TROUGH EJECTION WITH AREA OF STRONG UPPER LEVEL DIVERGENCE DEVELOPING WITHIN THE RIGHT ENTRANCE REGION OVER THE CWA. THE UPPER LEVEL SUPPORT COUPLED WITH LOW LEVEL ISENTROPIC ASCENT/THETA-E ADVECTION SHOULD SUPPORT A BROAD AREA OF LIFT SUN NGT INTO MON AM. GIVEN THE ANOMALOUS HIGH AVAILABLE MOISTURE WITHIN SUB-TROPICAL MOISTURE PLUME...FEEL ALL MODEL GUIDANCE MAY VERY WELL BE UNDER-FORECASTING QPF IN THE COLD SECTOR. SIGNIFICANT QPF OF A HALF INCH OR MORE IS POSSIBLE IN AREAS WHICH WILL BE AT OR BELOW FREEZING AT THE SURFACE...WITH HEAVIER AMOUNTS IN THE FAR SOUTHERN PART OF THE CWA WHERE DEEPER MOISTURE AND WARMER TEMPS ARE FORECAST.

NEXT QUESTION IS PTYPE. AGAIN...FAVORED THE NAM THERMAL PROFILES IN FAVOR OF A STRONGER AND FARTHER NORTH TRACK...WHICH WOULD IMPLY WARMER TEMPS ALOFT. NAM POINT SOUNDINGS FAVORABLE FOR FZRA AND IP ACROSS MUCH OF THE NORTHERN 2/3 OF THE CWA...WITH TENDENCY TOWARDS MORE SLEET FARTHER NORTH WITH A DEEPER NEAR SURFACE COLD LAYER. THE ONLY PORTION OF THE CWA WITH SOUNDINGS SUPPORT SNOW SUN NGT BASED ON CURRENT 12Z NAM RUN WOULD BE THE FAR NW CORNER FROM NEAR MCY TO BEH. FOLLOWING THIS TREND...HAVE REDUCED THE AMOUNT OF SNOW MENTION IN GRIDS AND INCREASED FZRA/IP MENTION. LEFT THE SOUTHERN 1/3 OF THE CWA AS MAINLY RAIN SUN NGT...POSSIBLY SOME FZRA LATE AS TEMPS COOL TO NEAR FREEZING. HAVE HOISTED A WINTER STORM WATCH FOR SUN NGT THROUGH MIDDAY MON FOR ROUGHLY THE NORTHERN 2/3 OF THE CWA FOR A COMBINATION OF FZRA AND SLEET...WITH SOME SNOW IN THE MIX AS WELL IN THE FAR NW. A FLOOD WATCH HAS ALSO BEEN HOISTED FOR THE SAME TIME FRAME ACROSS THE SOUTH FOR A COMBINATION OF POTENTIAL RIVER FLOODING AND ALSO POOR DRAINAGE TYPE FLOODING. STILL SOME UNCERTAINTY WITH EXACT TRACK AND SURFACE TEMPS...BUT IF THE EXPECTED GREATER QPF VERIFIES COULD SEE SIGNIFICANT ICE AND/OR SLEET ACCUMULATION FOR A PORTION OF THE CWA.

ON MONDAY SLOWER/WARMER NAM STILL FAVORS A MIXED BAG IN THE MORNING...THEN AS LOW/MID LEVEL CAA RAMPS UP IN THE AFTERNOON ANY REMAINING PRECIP SHOULD CHANGE TO ALL SNOW FROM NW TO SE. ATTENTION THEN TURNS TO LAKE EFFECT POTENTIAL. FROM LATE MON AFTERNOON THROUGH TUE NW FLOW OF MUCH COLDER AIR ARRIVES. 12Z NAM BUFKIT ANALYSIS SHOWING MODERATE COLLIER INDEX AND FAIRLY WELL ALIGNED NW FLOW WITH A GOOD AMOUNT OF AMBIENT SYNOPTIC SCALE MOISTURE BENEATH AN INVERSION CENTERED AROUND 7K FEET. INSTABILITY PARAMETERS AND PATTERN RECOGNITION POINT TOWARDS A POTENTIALLY DECENT LAKE EFFECT EVENT. THIS IS STILL SEVERAL DAYS OFF...AND WITH FOCUS ON SYNOPTIC EVENT STILL PLENTY OF TIME TO WATCH FUTURE MODEL TRENDS. FOR NOW HAVE INCREASED POPS TO LIKELY SE OF THE LAKE WITH A LARGE AREA OF CHANCE POPS IN AREAS FAVORED BY NW FLOW. LITTLE CHANGE TO REMAINDER OF FORECAST FROM TUE NGT THROUGH SAT.

&&

.IWX WATCHES/WARNINGS/ADVISORIES... IN...FLOOD WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR INZ020-INZ022-INZ023-INZ024-INZ025-INZ026-INZ027-INZ032- INZ033-INZ034.

FREEZING RAIN ADVISORY UNTIL 7 PM EST /6 PM CST FOR INZ008-INZ009-INZ013-INZ015-INZ016-INZ017-INZ018.

WINTER STORM WATCH FROM THIS EVENING THROUGH MONDAY AFTERNOON FOR INZ003-INZ004-INZ005-INZ006-INZ007-INZ008-INZ009-INZ012- INZ013-INZ014-INZ015-INZ016-INZ017-INZ018.

WINTER WEATHER ADVISORY UNTIL 7 PM EST /6 PM CST/ FOR INZ003-INZ004-INZ005-INZ006-INZ007-INZ012-INZ014.

MI...WINTER STORM WATCH FROM THIS EVENING THROUGH MONDAY AFTERNOON FOR MIZ077-MIZ078-MIZ079-MIZ080-MIZ081.

WINTER WEATHER ADVISORY UNTIL 7 PM EST FOR MIZ077-MIZ078-MIZ079-MIZ080-MIZ081.

OH...FLOOD WATCH FROM THIS EVENING THROUGH MONDAY AFTERNOON FOR OHZ016-OHZ024-OHZ025.

FREEZING RAIN ADVISORY FROM MIDNIGHT TONIGHT TO 7 PM EST SUNDAY FOR OHZ001-OHZ002-OHZ004-OHZ005-OHZ015.

WINTER STORM WATCH FROM SUNDAY EVENING THROUGH MONDAY AFTERNOON FOR OHZ001-OHZ002-OHZ004-OHZ005-OHZ015.

LM...NONE. &&

$$

SHORT TERM...HICKMAN LONG TERM....HITCHCOCK AVIATION...SKIPPER UPDATE...TAYLOR


AREA FORECAST DISCUSSION...UPDATED WWA SECTION
NWS TOPEKA KS
AFDTOP 1045 PM CST SAT JAN 13 2007

.DISCUSSION... WENT AHEAD AND REPLACED THE WATCH WITH ADVISORIES. WITH THE POSSIBILITY FOR A MIX OF SLEET AND SNOW...WENT WITH A WINTER WEATHER ADVISORY RUFFLY FROM EMPORIA TO HIAWATHA. SNOW IS EXPECTED TO BE THE PRIMARY PRECIP TYPE ACROSS NORTH CENTRAL KS...SO HAVE ISSUED A SNOW ADVISORY FOR THESE AREAS. THE WINTER STORM WARNING REMAINS UNCHANGED FROM PREVIOUS SHIFTS.

&&

WOLTERS

.PREV DISCUSSION /907 PM CST SAT JAN 13 2007/... WILL UPDATE THE FORECAST SHORTLY FOR CURRENT CONDITIONS. FOR THE MOST PART...PRECIP HAS ENDED ACROSS MOST OF THE FORECAST AREA. THERE ARE SOME SMALL BANDS OF VERY LIGHT PRECIP SEEN ON RADAR. IT IS HARD TO TELL IF THE PRECIP FALLING IS LIGHT FREEZING DRIZZLE OR POSSIBLY SNOW NEEDLES...ITS THAT LIGHT. THE LATEST RUC FORECAST WAS SHOWING SOME VERY LIGHT ISENTROPIC LIFT WITHIN THE CLOUD. THINK THIS MAY BE THE REASON FOR THE LIGHT PRECIP. NEVERTHELESS DO NOT ANTICIPATE ANY ACCUMULATING PRECIP FOR THE REST OF THE NIGHT SINCE LARGE SCALE FORCING HAS LEFT THE AREA FOR THE TIME BEING.

MAIN QUESTION IS WHAT TO DO WITH THE WATCH. AM CONSIDERING REPLACING THE WATCH WITH AN ADVISORY OF SOME SORT. THE 00Z NAM IS COMING IN SHOWING A SIMILAR SOLUTION TO THE DAY TIME RUNS. AS THE BASE OF THE UPPER LEVEL TROUGH ROTATES THROUGH THE SOUTHER ROCKIES AND INTO THE WESTERN CENTRAL PLAINS...LARGE SCALE FORCING IS EXPECTED TO AFFECT THE AREA ONCE AGAIN. HOWEVER THE FORCING DOES NOT LOOK TERRIBLY IMPRESSIVE WITH THE UPPER WAVE SHEARING OUT AS IT MOVES INTO THE PLAINS. WILL WAIT TO REPLACE THE WATCH AND PEEK AT THE 00Z GFS TO SEE IF IT SHOWS SOMETHING DIFFERENT FROM THE EARLIER RUNS. IF THE NAM IS CORRECT...LOOKS LIKE MAINLY SNOW WILL FALL ACROSS AREAS NORTH AND WEST OF MHK WITH AROUND 2 INCHES POSSIBLE. ALONG THE TURNPIKE WILL BE A LITTLE MORE PROBLEMATIC GIVEN FORECAST SOUNDINGS STILL SHOWING A WARM NOSE AROUND 800MB THROUGH 21Z. WILL KEEP THE WINTER STORM WARNING AS IS FOR THE TIME BEING...GIVEN THE POSSIBILITY FOR DECENT SLEET ACCUMULATIONS ONCE AGAIN.

AVIATION WISE...EXPECT CURRENT CONDITIONS TO REMAIN RELATIVELY STABLE THROUGH THE OVERNIGHT PERIOD. OBVIOUSLY THE LIGHT PRECIP SEEN ON RADAR WILL CAUSE A PROBLEM FOR AIRCRAFT. THIS SHOULD BE SPOTTY THOUGH AND CONFINED TO AREAS BELOW 4000FT. SFC VIS WILL DROP TO AROUND 4SM IN THESE LIGHT BANDS WITH CEILINGS AROUND 800FT. OTHERWISE ANTICIPATE A SLIGHT IMPROVEMENT TO THE CEILINGS AROUND 1000FT AS VERY WEAK ISENTROPIC LIFT BREAKS DOWN.

&&

WOLTERS

.PREV DISCUSSION /340 PM CST SAT JAN 13 2007/... CURRENTLY...SLEET SHOWERS EXITING THE CWA TO THE EAST WITH SOME LIGHT SNOW FILLING IN BEHIND. CONDITIONS HAVE IMPROVED ENOUGH TO LIFT ADVISORY ALL AREAS...AND WILL LET IT GO WITH THE AFTERNOON PACKAGE.

ANTICIPATING A LULL IN THE WEATHER FOR TONIGHT AS TODAYS SYSTEM DEPARTS EAST AND UPPER TROF STILL LUMBERING INTO THE GREAT BASIN. BASE OF THE MAIN TROF PROGGED TO MAKE IT INTO NORTHERN NM BY MORNING...EJECTING SHORTWAVES INTO SOUTH CENTRAL KANSAS AT THAT TIME AS WELL. GFS STRONGER WITH THESE FEATURES...AND WHILE SEVERAL WAVES ARE SEEN OVER THE SW US IN THE WATER VAPOR...STILL DIFFICULT TO DISCERN WHICH WILL MAKE IT HERE AND WHEN. CONSENSUS SEEMS TO BE THAT BEST WINDOW FOR ACCUMULATING SNOWS IS NOW MAINLY IN THE 15Z-0Z TIMEFRAME. GUIDANCE NUMBERS FOR SNOW HAVE COME DOWN...AND NOT MUCH INSTABILITY IN THE COLUMN. BUT WITH SOME FRONTOGENESIS...POT VORT AND Q VECTOR CONVERGENCE STILL OCCURING OVER OUR AREA AT THIS TIME...WILL KEEP SOME ADVISORY ACCUMULATIONS IN THE FORECAST FOR MUCH OF THE CWA. FAR SE COUNTIES WHERE WARNING IS IN EFFECT HAVE ALREADY SEEN OVER AN INCH OF SLEET IN PLACES...AND WILL BE EXACERBATED BY SOME SNOW ACCUMULATION ON TOP OF THIS TOMORROW. WITH PWS AROUND HALF AN INCH AND SNOW RATIOS LIKELY OVER 10/1 IN THE COLD AIR...AM NOT READY TO DROP THE WATCH JUST YET...AND WILL TREND GRIDS TOWARDS ADVISORY NUMBERS.

MAIN UPPER LEVEL WAVE FINALLY EJECTS OUT THROUGH THE PLAINS AND EXITS TO THE NORTHEAST OF THE CWA BY 12Z MONDAY...BUT NOT BEFORE PRODUCING SOME LIGHT SNOW ACROSS THE CWA...MAINLY DURING THE EVENING ALONG AND NORTH OF I-70 AS DRIER AIR AND SUBSIDENCE INCREASE FROM THE SOUTHWEST. ADDITIONAL AMOUNTS GENERALLY SHOULD BE FROM LESS THAN HALF AN INCH SOUTH TO AN INCH TO AN INCH AND A HALF NORTHEAST CORNER OF THE CWA. ALTHOUGH LOWS SUNDAY NIGHT WILL BE COLDER...CLOUDS AND INCREASING WINDS WILL KEEP TEMPERATURES FROM FALLING AS MUCH AS THEY OTHERWISE WOULD...SO WILL KEEP GENERALLY IN THE 5 TO 12 DEGREE RANGE. THE STRATUS ON MONDAY WILL THEN LINGER IN THE MORNING BUT START TO BREAK UP BY AFTERNOON. STILL...WITH EXPECTED SNOW/ICE COVER...THIS WILL LIMIT HIGHS TO THE TEENS.

TUESDAY NIGHT SHOULD BE THE COLDEST NIGHT WITH DIMINISHING WINDS...DECREASING CLOUDS AND SNOW/ICE COVER. WILL GO WITH MOST TEMPS NEAR ZERO FOR NOW...BUT DEPENDING ON SNOW/ICE DEPTHS...COULD SEE TEMPS A FEW DEGREES COLDER. ALTHOUGH SUNSHINE SHOULD BE THE RULE ON TUESDAY...MIXING WILL BE WEAK FOLLOWING VERY COLD MORNING LOWS...SO THIS WILL LIMIT HIGHS TO UPPER TEENS TO LOWER 20S. RETURN FLOW ON THE BACK SIDE OF THE HIGH SHOULD THEN KEEP LOWS ABOVE ZERO INTO WEDNESDAY MORNING WITH MOST HIGHS IN THE MIDDLE TO UPPER 20S. WILL KEEP THE REST OF THE FCST DRY ON THROUGH EARLY NEXT WEEKEND AS THE GFS/ECMWF SEEMS TOO PROGRESSIVE AND TOO FAR EAST WITH CUTOFF LOW COMING OUT OF THE SOUTHWEST U.S. WEDNESDAY. ALSO LOW CONFIDENCE WITH THE ARRIVAL TIME OF THE NEXT SYSTEM BY SATURDAY.

EITHER WAY...WITH THE SNOW/ICE COVER WILL SEE A "GRADUAL" MODERATION IN TEMPS THROUGH THE REST OF THE WEEK INTO THE 30S THURSDAY AND FRIDAY AND SOME LOWER 40S SOUTHERN CWA BY NEXT WEEKEND.

&&

.TOP WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING THROUGH 06Z MONDAY FOR COFFEY...FRANKLIN AND ANDERSON COUNTIES.

WINTER WEATHER ADVISORY FROM 16Z SUNDAY UNTIL 06Z MONDAY FOR LYON... MORRIS...WABAUNSEE...OSAGE...SHAWNEE...DOUGLAS...JEFFERSON...JACKSON AND BROWN COUNTIES.

SNOW ADVISORY FROM 16Z SUNDAY UNTIL 06Z MONDAY FOR ALL OTHER COUNTIES.

&&

$$


AREA FORECAST DISCUSSION
NWS MARQUETTE MI
AFDMQT 430 PM EST SUN JAN 14 2007

.SYNOPSIS AND SHORT TERM...

WATER VAPOR LOOP AND RUC/LAPS ANALYSIS SHOW SOUTHWEST FLOW ALOFT BUT COLDER AIR REMAINS ENTRENCHED OVR PLAINS INTO UPR LAKES. FRONTAL BOUNDARY HAS SLIPPED SOUTH OF UPR MI ATTM. WINDS BECOMING NORTHERLY IN WAKE OF TROUGH. DESPITE LOW INVERSION AROUND 3 KFT PER MIDDAY TAMDAR DATA AT CYQT AND KSAW...LK EFFECT HAS BEEN PROFICIENT WITH SOME ACCUMS REPORTED BY SPOTTER IN MOHAWK IN HOUGHTON COUNTY. LATEST RADAR AND VIS SAT EVEN SHOW ENHANCED CONVERGENCE BAND BTWN MQT AND STDM4 OVR SCNTRL LK SUPERIOR. TO THE SW OF UPR LAKES LARGE AREA OF MOSTLY SNOW IS LIFTING NE ACROSS NEB AND WESTERN IA. THIS SNOW IS ASSOCIATED WITH MID LEVEL LOW IN CNTRL KS AND IT NOW LOOKS LIKE THIS SNOW WILL MAKE IT INTO UPR MI LATE TONIGHT INTO MONDAY. SNOW AMOUNTS AND HEADLINES ARE MAIN CONCERNS IN SHORT TERM.

NORTHERLY FLOW TONIGHT WITH TEMPS AT TOP OF INVERSION AROUND -17C WILL KEEP LK EFFECT GOING THROUGH EVENING. NOTED CONVERGENCE BAND MAY ENHANCE SNOWFALL BRIEFLY THIS EVENING OVR NCNTRL. OTHERWISE... EXPECT SNOW TO INCREASE AFTER MIDNIGHT AS SYNOPTIC SNOW ARRIVES FM THE SOUTH. HOW FAR NORTH WILL SHIELD OF DEEPER MOISTURE/UPR LEVEL FORCING AND SYNOPTIC SNOW SURGE WAS MAIN QUESTION OF THE SHIFT. UNLIKE YDY FOR THE MOST PART GFS/NAM/UKMET/ECMWF/CANADIAN GEM ARE ALL ON SAME PAGE. BLEND OF QPF OUTPUT GIVES MOST AREAS A SOLID 0.20 TO 0.25 INCHES OF LIQUID 00Z MON THROUGH 00Z TUE. USING BUFKIT COBB SNOW-WATER RATIOS AND UWM ROEBBER SNOW RATIO FORECAST PAGE GIVES HIGHER RATIO THAN TYPICAL SYNOPTIC EVENT...MORE IN LINE WITH 15-20 TO 1. IN GENERAL...THIS GIVES TOTAL AMOUNTS OF 3 TO 5 INCHES OVR SOUTHERN TIER...WHICH JUSTIFIES AN ADVY THROUGH LATE TOMORROW. COORD THIS WITH DLH AND GRB.

BASED ON AIRMASS OVERHEAD AND WAY LK EFFECT HAS TURNED OUT LAST FEW DAYS...EXPECT EVEN HIGHER RATIOS OVR PRONE LK EFFECT AREAS. LOWER LEVEL WINDS THROUGH H85 ON AVERAGE FM 360 DIRECTION...ALTHOUGH NAM/CANADIAN GEM ARE A BIT MORE TOWARD 030. INVERSION HEIGHTS ARE FAIRLY LOW...5-7KFT...BUT WITH DEEP MOISTURE PRESENT...AND TEMPS AT TOP OF INVERSION TOWARD -18C...SIGNIFICANT LAKE CONTRIBUTION IS EXPECTED. UPGRADED TO LK EFFECT SNOW WARNING FOR FAR WEST AND NCNTRL UPR MI. SOME LOCALIZED AREAS MAY SEE AROUND A FOOT OF SNOW FM THE EVENT. ALTHOUGH WINDS ARE NOT AS FAVORABLE FOR OTHER ZONES NEAR LK SUPERIOR...SYNOPTIC MOISTURE AND SOME LAKE CONTRIBUTION TIPS SCALES TOWARD ADVY FOR ALL BUT LUCE COUNTY AS NORTHEAST WINDS DO NOT PRODUCE PROVIDE SUITABLE FETCH FOR LK INDUCED CONVECTION. ONE NOTE ABOUT THE KEWEENAW. AIRMASS LURKING OVER NORTHERN LAKE SUPERIOR IS QUITE DRY AND SOUNDINGS EVEN FM THE HIGHER RESOLUTION MODELS INDICATE SHARP CUTOFF TO DEEPER MOISTURE. THIS MAY IMPACT INTENSITY OF INDIVIDUAL SNOW BANDS. STILL...SINCE LAKE IS SHOWING NO ICE ON IT AND WATER TEMPS ARE RUNNING +3C TO +4C AND THERE IS SOME SYNOPTIC SUPPORT...BELIEVE THE HIGHER TERRAIN OF NORTHERN KEWEENAW AND TOWARD ONTONAGON COUNTY COULD EEK INTO ADVY CRITERIA. ALL LK SUPERIOR HEADLINES EXPIRE LATE MON EVENING.

.LONG TERM...(MON NIGHT THROUGH SUNDAY)

MON NIGHT...AS THE SYNOPTIC SCALE SUPPORT WITH THE QVECTOR CONV WITH THE MID LVL TROF AND DEEPER MOISTURE DEPARTS THE SNOW OVER SOUTH UPPER MICHIGAN WILL TAPER OFF QUICKLY EARLY IN THE EVENING...AND THE LES INTENSITY NORTH WILL DIMINISH SIGNIFICANTLY. HOWEVER...THE NAM AND GFS CONTINUE TO INDICATE DECENT LOW LEVEL CONV INTO N CNTRL UPPER MI (VCNTY MARQEUTTE) AND OVER THE WEST(NEAR KIWD) THROUGH 06Z. TEMPS OF -18C NEAR THE TOP OF THE 4K FT INVERSION SHOULD STILL FAVOR BANDS OF LIGHT TO MODERATE LES. AS THE WINDS BACK TO NW OVERNIGHT THE LES FOCUS WILL SHIFT INTO AREAS FROM KP53 EASTWARD. THE SHORTER FETCH INTO W UPR MI AND EVEN LOWER INVERSION HEIGHTS SHOULD ALLOW LES TO TAPER OFF TO JUST LIGHT SNOW OR FLURRIES WITH ONLY MINOR AMOUNTS AFT 06Z.

TUE...ALTHOUGH THE SFC RDG WILL BUILD INTO THE AREA...LAKE INDUCED TROUGHING WILL KEEP NW OR NW WINDS GOING WITH BEST LOW LVL CONV EAST OF MARQEUTTE. BY AFTERNOON...THE COMBINATION BACKING WINDS AND ADDITIONAL LOW LEVEL DRYING...WAA AND BACKING WINDS SHOULD BRING AN END TO ANY SIGNIFICANT LES. THE EXCEPTION WILL BE OVER THE FAR E CWA WHERE LONGER FETCH AND CLOSER PROXIMITY TO THE DEPARTING 850 MB THERMAL TROF WILL KEEP LIGHT LES GOING.

WED INTO THU...GLBL MDLS ARE CONSISTENT WITH PATTERN WITH STRONG WAA DEVELOPING AS THE SFC RDG SINKS SE AND A PLAINS SHRTWV AND SFC TROF MOVE TOWARD THE AREA. AS A RESULT...TEMPS SHOULD REBOUND TO READINGS AOA NORMAL WED. MODERATE QVECTOR CONV WITH THE PROMINENT 500 MB TROF WARRANT AT LEAST CHANCE POPS ACROSS THE CWA WITH LES CHANCES INCREASING BY LATE THU AS CAA TAKES OVER BEHIND THE SFC FRONT/TROF AS 850 MB TEMPS FALL TO NEAR -15C.

FRI THROUGH SUN...GOOD LES CHANCES CONTINUE IN GENERAL FOR NW FLOW FAVORED LOCATIONS. NW NORTHERN STREAM FLOW WILL BRING A FEW CLIPPER SHRTWVS THROUGH THE AREA BUT LESS CERTAINTY WITH TIMING/STRENGTH OF THESE FEATURES AND IMPACT ON WIND DIRECTION.

&&

.MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW ADVISORY FROM 11 PM THIS EVENING TO 11 PM EST MONDAY FOR MIZ001>004-006-084-085.

LAKE EFFECT SNOW WARNING FROM 11 PM EST /10 PM CST/ THIS EVENING TO 11 PM EST /10 PM CST/ MONDAY FOR MIZ005-009.

SNOW ADVISORY FROM 1 AM TO 11 PM EST MONDAY FOR MIZ013.

SNOW ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST MONDAY FOR MIZ010>012.

&&

$$

JLA(SHORT TERM) JLB(LONG TERM)


AREA FORECAST DISCUSSION
NWS SEATTLE WA
AFDSEW 835 AM PST SUN JAN 14 2007

.SYNOPSIS...A COLD AND DRY AIR MASS WILL REMAIN OVER WESTERN WASHINGTON THROUGH MONDAY NIGHT. A PACIFIC FRONTAL SYSTEM WILL PASS THROUGH THE AREA TUESDAY. DRY WEATHER WILL RETURN TO THE AREA WEDNESDAY AND THURSDAY. ANOTHER WEATHER SYSTEM WILL BRING ANOTHER CHANCE OF PRECIPITATION TO THE AREA TOWARD THE END OF THE WEEK.

&&

.SHORT TERM...COLD AIR HAS A GRIP OVER THE STATE AND WESTERN WASHINGTON TEMPERATURES RANGE FROM THE MID TEENS TO THE 20S THIS MORNING. MOISTURE OFF THE SOUND AND UNFROZEN LAKES ARE RESULTING IN AREAS OF FREEZING FOG MAKING SOME ROADS SLICK AND LOCALLY REDUCING VISIBILITIES TO A MILE OR SO. THE FOG IS SHALLOW AND SHOULD BURN OFF MIDDAY. REALLY LIGHT OFFSHORE PRES GRADIENTS COMBINED WITH A ISOTHERMAL LAPSE RATE AT SEATTLE FROM THE SURFACE TO 10000 FT PER ACARS SOUNDINGS...SOME SNOW ON THE GROUND...AND LOW MID JAN SUN ANGLES ALL POINT TO TEMPERATURES TODAY STRUGGLING TO GET ABOVE FREEZING. CI MOVING AROUND THE RIDGE AT 132W WILL OCCASIONALLY SPILL INTO THE AREA FILTERING THE AFTN SUNSHINE.

TONIGHT WILL BE QUITE COLD AGAIN...THOUGH SOME HIGH CLOUDINESS MAY KEEP TEMPERATURES ABOUT 2 DEG HIGHER THAN THIS MORNING MOST AREAS.

TEMPERATURES WILL CONTINUE TO MODERATE ON MON BY A COUPLE DEGREES THOUGH SUNSHINE WILL BE FILTERED BY A THICKENING LAYER OF HIGH CLOUDS. AIR MOVEMENT WILL CONTINUE TO BE MINIMIZED BY LIGHT GRADIENTS AND INCREASING TEMPERATURE INVERSIONS TONIGHT AND MON.

STAGNATION WILL CONTINUE TO BE AN ISSUE THRU MON NIGHT WITH THE VERY STABLE AIR MASS IN PLACE AND LIGHT PRES GRADIENTS. WILL MAINTAIN THE AIR STAGNATION ADVISORY THRU MON NIGHT OR TUE MORNING.

THE NEXT PROBLEM IN THE FORECAST WILL BE LATE MON NIGHT AND TUE. BOTH THE NAM AND THE GFS SHOW A SPLITTING FRONT MOVING INTO THE AREA TUE MORNING. WHILE TEMPERATURES ARE VERY SLIGHTLY ABOVE FREEZING IN THE LAYER FROM 1000 FT TO 3000 FT...THE AIR MASS WILL BE QUITE DRY AND PRES GRADIENTS WITH THE INCOMING FRONT WILL BE WEAKLY OFFSHORE. MODEL QPF WITH THE INCOMING FRONT IS ON THE ORDER OF 0.15-0.40 INCHES ACROSS THE AREA TUE...AND LOW LEVEL THICKNESS ARE AROUND 1295 M. A QUICK LOOK AT NAM BUFR SOUNDING FORECASTS AS WELL AS FORECAST SOUNDINGS OFF THE INCOMING GFS ALL POINT TO MOST AREAS IN THE INTERIOR SEEING SNOW TUE MORNING WITH POSSIBLE ACCUMULATIONS IN THE 2-4 INCH RANGE. PCPN MAY CHANGE TO RAIN SHOWERS WITH THE PASSAGE OF THE FRONT DURING THE DAY SEATTLE SOUTHWARD...BUT SNOW LEVELS REMAIN QUITE LOW...AND ANY POST FRONTAL CONVERGENCE LATE IN THE DAY INTO EARLY WED MORNING COULD STILL CAUSE FROZEN PCPN ON HILLS N/E OF SEATTLE. WILL CONTINUE TO EVALUATE THIS BEFORE THE AFTERNOON PACKAGE GOES OUT. ALBRECHT.

.LONG TERM...LONG TERM MODELS NOT SHOWING A LOT OF RUN TO RUN CONSISTENCY BUT THE GENERAL TREND IS FOR MORE SHORT WAVE RIDGING FOR WEDNESDAY AND THURSDAY THEN ANOTHER SYSTEM MOVING INTO THE AREA FRIDAY INTO SATURDAY. 00Z RUNS A LITTLE FASTER AND GIVEN THE EXTENDED MODELS HAVE GIVEN THE RIDGES A LITTLE TOO MUCH STRENGTH IN THE LAST FEW RUNS WILL GO AHEAD AND MOVE UP THE CHANCE POPS TIMING INTO THE FIRST HALF OF FRIDAY. CONFIDENCE NOT HIGH IN THE EXTENDED AT THIS POINT. FELTON

&&

.AVIATION...INCREASING HIGH CLOUDS DURING THE DAY...OTHERWISE EXPECT AREAS OF 1/4-1/2SM FZFG CIGS BKN001-003 TO MOSTLY DISSIPATE BY 20Z. CONTINUED WEAK LOW LEVEL OFFSHORE FLOW.

KSEA...FOG IS EXPECTED TO REMAIN OUTSIDE THE AIRPORT COMPLEX. MEANWHILE...WINDS WILL BE LIGHT AND VARIABLE WITH MAINLY HIGH CLOUDS ANTICIPATED.

&& .SEW WATCHES/WARNINGS/ADVISORIES...AIR STAGNATION ADVISORY INTERIOR LOWLANDS THROUGH TUESDAY MORNING.

$$

WEATHER.GOV/SEATTLE.