AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
AFDLOT 550 AM CST SAT JAN 13 2007
.DISCUSSION...
...MAIN CONCERN THIS MORNING CONTINUES TO BE POTENTIAL HVY SNOWFALL
SUNDAY NIGHT INTO MONDAY MORNING BUT NO HEADLINES FOR NOW...
COMPLEX SITUATION EVOLVING OVER THE NEXT 72 HRS AND MODELS THIS
MORNING ARE NOT IN TOO GOOD AGREEMENT. HOWEVER...WILL PUSH THRU THE
DIFFERENCES AND HOPE TO ARRIVE AT THE MOST LIKELY SCENARIO.
IN THE SHORT TERM...FIRST WAVE PULLING OUT WITH PRECIP SLOWLY ENDING
FROM WEST TO EAST ACROSS THE SOUTHERN HALF OF THE CWA. PRECIP HAS
REMAINED PREDOMINANTLY RAIN AND WHERE PRECIP HAS CHANGED OVER TO A
MIX...IT HAS BEEN LIGHT WITH A SHORT DURATION. WILL CONTINUE TO
WATCH RADAR TRENDS BUT EXPECT THE BULK OF THE PRECIP TO BE OUT OF
ALL BUT THE FAR SE CWA BY DAWN AND PLAN TO CARRY JUST A CHANCE OF
LIGHT RAIN OR DRIZZLE ACROSS THE SOUTH THIS MORNING AND SHOULD BE
ABLE TO CANCEL THE REST OF THE -FZRA ADVISORY WITH MORNING ZFP. WILL
ALSO CARRY -DZ/-FZDZ THIS MORNING WITH A FEW LOCATIONS STILL
REPORTING MIXED PRECIP.
TEMPS CLIMB A FEW DEGREES FROM AM LOWS GENERALLY IN THE LOWER 30S
NORTH TO UPPER 30S SE. NEXT WEAK WAVE ARRIVES TONIGHT AND DESPITE
LIKELY POPS OFF GUIDANCE...QPF AMOUNTS ARE RATHER LIGHT. LOOKING AT
THE SOUNDINGS AND THERMAL PROFILES AND WARMER SFC TEMPS...THINK THE
SOUTHERN PART OF THE CWA MAY REMAIN JUST RAIN WITH A MIX ACROSS THE
MIDDLE PART OF THE CWA TO SNOW NORTH. WILL MODIFY FORECAST ALONG
THESE LINES. DEPENDING ON HOW MUCH MIXED PRECIP OCCURS...AN ADVISORY
MAY BE NEED AGAIN FOR TONIGHT BUT WILL HOLD OFF ON HEADLINES. PRECIP
TAPERS OFF SUNDAY MORNING WITH ANOTHER LULL DURING THE DAYLIGHT HRS
AND HAVE BACKED OFF TO CHANCE POPS.
THEN COMES THE MAIN SHOW SUNDAY NIGHT. HAVE WATCHED THE MODELS FOR
THE PAST 4 DAYS WITH THIS SYSTEM. SOME HIGHLIGHTS INCLUDE THE GFS
BEING RATHER CONSISTENT WITH A MORE SOUTHERLY AND WEAKER TRACK OF
THE SFC LOW. THE NAM REMAINING FURTHER NORTH OF THE GFS ON EVERY
RUN...TRYING TO TREND TOWARD THE GFS A FEW DAYS AGO BUT NOW BACK TO
A DEEPER AND FARTHER NORTH TRACK AND EVEN SHOWING SOME SIGNS OF
TRYING TO BECOME NEGATIVELY TILTED. BY 12Z MONDAY THE GFS IS THE
FARTHEST SE WITH THE UKMET NEARBY AND THE ECMWF/CANADIAN SLIGHTLY
MORE NORTH BUT NOT AS MUCH AS THE NAM...THOUGH THEY ARE A LITTLER
FARTHER NORTH THEN PREVIOUS RUNS. WITH HIGH PRESSURE ACROSS THE
PLAINS BEGINNING TO WEAKEN AND RAPIDLY WEAKENING TODAY/TONIGHT...
DOUBT COLD FRONT WILL MOVE MUCH FARTHER SOUTH AND WILL LIKELY
BECOME STATIONARY THIS MORNING FARTHER NORTH THAN MODELS SUGGEST.
SFC LOW WILL RIDE CLOSE TO THIS BOUNDARY AND AS A RESULT PREFER THE
NAM STRENGTH AND FARTHER NORTH TRACK...THOUGH FINAL TRACK MAY END
UP CLOSER TO MODEL CONSENSUS. ALSO PREFER SLIGHTLY SLOWER TIMING.
A QUICK LOOK AT THE 06Z NAM LOOKS VERY SIMILAR TO THE 00Z RUN.
WITH THIS IN MIND...PRECIP DEVELOPS LATE SUNDAY AFTERNOON AND
SPREADS NE ACROSS THE ENTIRE AREA SUNDAY EVENING. PLENTY OF
MOISTURE FOR THIS SYSTEM TO WORK WITH AND A PERIOD OF SNOW...
POSSIBLY HEAVY SNOW...ACROSS THE NORTHERN TWO THIRDS OF THE CWA
LOOKS GOOD...TAPERING OFF TO FLURRIES AFTER SUNRISE MONDAY MORNING.
PROBLEM FURTHER SOUTH WILL BE PRECIP TYPE. NOT SURE EVEN MDT/HVY
PRECIP COULD OVERCOME LARGE DEPTH OF WARM AIR...AT LEAST IN THE
WARMEST SCENARIO AND WILL KEEP A MIX OF PRECIP SOUTH OF A LINE FROM
PNT TO GYY...WHICH WILL KEEP SNOW AMOUNTS LOWER THERE. GOING
FORECAST INDICATES 6+ INCHES NORTH OF A LINE FROM GYY/PNT. SEE
LITTLE REASON TO DEVIATE FROM THIS FORECAST. HOWEVER...HAVE DECIDED
TO HOLD OFF ON A WATCH THIS MORNING FOR A FEW REASONS. DESPITE
PREFERENCE TO THE NAM...IT IS THE FARTHEST NORTH. MIXED PRECIP
TONIGHT MAY NEED AN ADVISORY AND A WATCH FOR 4TH PERIOD MAY CONFUSE
OR CAUSE 2ND PERIOD POTENTIAL PROBLEMS TO BE OVERLOOKED. SO WILL
DEFER WATCH/ADVISORY TO THE DAY SHIFT AND HOPEFULLY THE MODELS WILL
SHOW A CLEARER PICTURE.
AS FOR LAKE ENHANCEMENT AND LAKE EFFECT...WATER TEMPS IN THE UPPER
30S OR +3C TO +4C. DURING THE MAIN SNOW SUNDAY NIGHT...THERE MAY BE
SOME ENHANCEMENT BUT IT APPEARS MINIMAL AT THIS POINT. 850MB TEMPS
REALLY DON/T DROP OFF UNTIL MONDAY AFTERNOON FOR FAVORABLE LAKE
EFFECT AND THEN CONTINUE TO DROP MONDAY NIGHT INTO TUESDAY AS WINDS
TURN MORE NORTH AND NORTHWEST. AM MORE CONCERNED ABOUT LAKE EFFECT
SNOW DURING THIS TIME WHEN DELTA T`S REACH 20 DEGREES BY TUESDAY
AFTERNOON WITH INVERSION HEIGHTS OF 7-8KFT. FOR NOW WILL INCLUDE
CHANCE OF SNOW SHOWERS BUT THIS TOO WILL NEED TO BE WATCHED FOR
ACCUMULATING SNOW...ESPECIALLY ACROSS NORTHWEST INDIANA.
&&
.AVIATION DISCUSSION REGARDING 12Z TAFS...
CURRENT SATLT IMAGERY SHOWS EXTENSIVE CLOUD DECK OVER THE MIDWEST
ASSD WITH A DAMPENING SHORT WAVE TROF NOW EJECTING ENEWD ACRS THE
MID MS VLY. PCPN WITH THIS FEATURE HAS SHIFTED S AND E OF THE
TERMINAL AREA. THERFORE...EXPECT TDY TO BE GENLY FREE OF PCPN WITH
NO VIS RESTRICTIONS. WILL KEEP CIGS IN MVFR RANGE. SFC OBS PAST
SVRL HRS HAVE SUGGESTED PERSISTENT NELY FLOW BLO FRONTAL INVERSION
(BLO ABOUT 25 HND FT BASED ON ACARS) HAS ERODED AWAY LOWER CLOUDS.
THIS WILL CONTINUE THRU TDY AS NELY LLVL FLOW CONTS TO ADVECT LOW
DEW POINT AIR FROM SRN WI/LWR MI INTO RGN.
NXT WX PROBLEM FCST TO ARRIVE TNGT. SATLT LOOPS SHOW ANOTHER MINOR
DISTURBANCE LIFTING NEWD FROM WRN TX ERLY THIS MRNG. THE FACT THAT
IT IS TRIGGERING THUNDER AS FAR N AS THE TX PHDL SUGGESTS IT IS A
FAIRLY DYNAMIC LITTLE FEATURE. AS THIS WAVE REACHES THE MIDWEST
THIS EVENING...SOME LIGHT PCPN IS EXPECTED TO OVERSPREAD THE
RGN...MAINLY IN 03Z-09Z TIME FRAME. FCST SOUNDINGS SUGGEST PCPN
WILL BE LGT SNOW RFD-ORD-DPA AREAS...WITH SOME ICE PELLETS
MDW-ARR-PNT AND RAIN/FZRA/ICE PELLETS VPZ-IKK. AGAIN...THIS IS
EXPECTED TO BE A MINOR EVENT...BUT CIGS/VIS WILL LIKELY LWR TO IFR
AGN OVERNGT.
MERZLOCK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
.IL...NONE.
.IN...NONE.
.LM...SMALL CRAFT ADVISORY FOR ALL NEAR SHORE UNTIL 15Z.
&&
$$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
AFDLOT 1145 PM CST FRI JAN 12 2007
.EVENING UPDATE...
820 PM CST
ZFP/GRIDS/WSW OUT. FOCUS OF THIS UPDATE WAS ON RAIN FALLING ACROSS
SOUTHERN CWA. CALLS TO LIVINGSTON...FORD...AND LA SALLE COUNTY IN
THE PAST HR OR SO INDICATE NO ICING PROBLEMS. PNT/TIP/IKK STILL
ABOVE FREEZING AND REPORTING RAIN. COLD AIR WILL SLOWLY SINK SOUTH
AND EXPECT RAIN TO SLOWLY CHANGEOVER TO FREEZING RAIN EVENTUALLY.
BUT BY THE TIME IT DOES MAKE A CHANGE...QPF AMOUNTS WILL BE LIGHT.
INDICATED UP TO ONE TENTH OF AN INCH OF ICE IN THE WSW ACROSS THIS
AREA...BUT THIS WILL BE ISOLATED. WITH CHANGEOVER OCCURRING LATER...
PUSHED FREEZING RAIN ADVISORY TO 12Z ACROSS THE SOUTHERN HALF OR SO
OF THE CWA.
FURTHER NORTH...ADVISORY EXPIRED FOR NW IL AND THAT LOOKS ON TRACK.
WAS RELUCTANT TO PULL ADVISORY FOR NE IL THOUGH AREAS NORTH OF I-88
APPEAR TO STAY MAINLY DRY THRU THE NIGHT. THOUGH ORD IS REPORTING
-DZ THIS HR AND -RA AT MDW. WHILE SFC TEMPS REMAIN ABOVE FREEZING
HERE...TEMPS COULD DIP BELOW FREEZING BEFORE 2AM. SINCE THE ADVISORY
WAS ALREADY OUT...DECIDED TO LET IT RIDE FOR NOW...BUT PRECIP WILL
BE LIGHT AND IMPACTS SHOULD BE SMALL.
&&
.PREVIOUS DISCUSSION...
400 PM CDT
THE FIRST ISSUE IS THE FREEZING RAIN TONIGHT. WE HAVE ADVISORY FOR
ALL OF THE CWA AT ONE TIME OR ANOTHER. THE COLD FRONT WAS FROM GARY
INDIANA TO ST LOUIS AT 19 UTC. AS THE COLD AIR MOVES INTO NORTHEAST
ILLINOIS AND NORTHWEST INDIANA...WARM AIR OVERRIDES IT AND THIS
CREATES PRECIPITATION. USING A CROSS SECTION OF EQUIVALENT POTENTIAL
TEMPERATURE WE SEE THAT THIS COLD AIR IS SHALLOW. UP TO THE 800 MB
LEVEL. ACARS SOUNDINGS AT ORD SHOWS THE AIR ABOVE FREEZING UP TO 737
MB. WEST OF A LINE FROM BOONE MCHENRY BORDER TO EASTERN FORD COUNTY
THE DRIZZLE AND FREEZING RAIN HAS BEGUN. EAST OF THAT LINE THE
TEMPERATURE HAS NOT FALLEN BELOW 0 DEGREES C NEAR THE SURFACE AND UP
TO 800 MB YET.
THE FORECAST SOUNDING FROM THE LOCALLY RUN WRF ARW MODEL SHOWS A
LAYER OF THE ATMOSPHERE FROM 896 MB TO 716 MB ABOVE FREEZING. ABOVE
THAT THE MOISTURE IN THE AIR IS NEARLY IN EQUILIBRIUM WITH THE VAPOR
PRESSURE OF WATER. THIS IS AROUND PONTIAC. THERE MAY BE SOME ICE
CRYSTAL FORMING AND SO WE WILL ADD ICE PELLETS FOR BENTON COUNTY
INDIANA TONIGHT. OTHERWISE WE WILL FORECAST DRIZZLE AND FREEZING
RAIN TONIGHT UP TO AROUND 2 AM. AFTER 06 UTC THE ISENTROPIC LIFT
ON THE 285K SURFACE DECREASES AND THERE WILL BE COLD AND DRIER AIR
INTO THE REGION.
THE SNOW STORM ON SUNDAY THROUGH MONDAY WILL BE THE NEXT WEATHER
EVENT. WE USED THE GFS...NAM AND NGM MODELS FOR THIS FORECAST. A
CYCLONE IS FORECAST TO DEVELOP IN TEXAS. 850 MB AND 1000 MB
TEMPERATURE GRADIENTS AND TEMPERATURE ADVECTION ARE OPERATED ON BY A
LAPLACIAN AND INTEGRATED UP TO 850 MB SHOW INCREASE IN LOW LEVEL
VORTICITY OVER ARKANSAS BY 00 UTC MONDAY. A LOW WILL DEVELOP THERE
AND MOVE INTO KENTUCKY BY 06 UTC MONDAY. THE TRACK OF THE 850 MB
TROUGH AND Q VECTORS PUT AN AREA OF LIFT MOVING FROM SOUTHEAST IOWA
AND MOVES IT THROUGH CHICAGO BY 12 UTC MONDAY. THIS WILL PROVIDE
SOME FORCING FOR SNOW SUNDAY NIGHT AND EARLY MONDAY MORNING.
THICKNESS FORECAST SHOW THE SOUTHERN THIRD OF THE FORECAST AREA WILL
HAVE SOME MIXED PRECIPITATION FREEZING RAIN AND ICE PELLETS. THERE
IS ENOUGH MOISTURE ABOVE -12 DEGREES CELSIUS THAT ICE CRYSTALS WILL
FORM AND FALL. THERE MAY BE SUPERCOOLED WATER DROPS AS WELL SUNDAY
AND SUNDAY AFTERNOON. BY SUNDAY NIGHT THE WHOLE COLUMNOF AIR MAY BE
COLD ENOUGH FOR SNOW. WE WILL FORECAST ALL SNOW SUNDAY NIGHT INTO
MONDAY. THIS STORM EVENT WILL END MONDAY AFTERNOON. THE LOW WILL
MOVE INTO PENNSYLVANIA. WE EXPECT ABOUT 4 TO 7 INCHES OF SNOW FOR
THE WHOLE AREA BY MONDAY AFTERNOON AT THIS TIME.
&&
.AVIATION...
1045 PM CST
RE THE 06Z TAFS...CDFNT CONTS TO PUSH SEWRD INTO LWR GRTLKS AND LWR
OH VALLEY. STRONGEST PUSH OF LLVL COLD AIR THIS EVE HAS BEEN SWRD FM
THE UPR MIDWEST AND NRN PLAINS AND ACROSS NW INTO W CNTRL IL. THIS
HAS RESULTED IN SIGNIFICANT ICING FM MO NEWRD INTO CNTRL IL...WHILE
FURTHER TO THE E SFC TEPS STILL ABV FREEZING SO JUST RA FALLING.
PROFILERS AND 00Z RAOBS SHOWING 40KT FEED OF GULF MOISTURE INTO THE
BAROCLINIC ZONE CURRENTLY LAYING OUT SW-NE FM MO INTO THE NRN OH. AS
THIS ZONE SAGS SWRD THE NRN EDGE OF THE PRECIP WILL ALSO SAG S AND
OUT OF TERMINALS DURG THE NEXT FEW HRS. PRECIP EXPECTED TO START TO
RETURN NWRD LATE SAT AFTERNOON AND SPREAD TO TERMINALS DURG SAT EVE
AS WRN U.S. UPR GRADUALLY MOVS TO ROCKIES INDUCING THE MID LVL FLO
TO BACK A BIT. BETWEEN END OF PRECIP LATE TONIGHT AND RETURN ON SAT
EVE EXPECT CIGS TO LIFT TO PREVAILING MVFR AS LOER SFC DWPTS FEED IN
ON N TO NE WNDS.
TRS
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
.IL...FREEZING RAIN ADVISORY MCHENRY LAKE COOK DUPAGE KANE KENDALL
WILL UNTIL 08Z.
FREEZING RAIN ADVISORY LASALLE GRUNDY KANKAKEE LIVINGSTON FORD
IROQUIOUS UNTIL 12Z.
.IN...FREEZING RAIN ADVISORY LAKE AND PORTER UNTIL 08Z.
FREEZING RAIN ADVISORY NEWTON JASPER BENTON UNTIL 12Z.
.LM...SMALL CRAFT ADVISORY FOR ALL NEAR SHORE UNTIL 15Z.
&&
$$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
AFDIWX 1059 PM EST SUN JAN 14 2007
.UPDATE...
GETTING 1/8" GLAZING REPORTS ON TREES JUST NORTH OF SOUTH BEND LATE
THIS EVE. BASED ON SFC OBS EXPECT SIMILAR CONDITIONS THROUGHOUT THE
ADVISORY AREA WITH THE PSBL EXCEPTION OF URBAN AREAS OF SOUTH
BEND/ELKHART DECIDED TO UPGRADE FREEZING RAIN ADVISORY TO AN ICE
STORM WARNING. ALSO GETTING SCT REPORTS OF ICING FARTHER SOUTH AND
WITH DFI TEMP AT 32 LAST SEVERAL HOURS AND FWA TEMP/DWPT FALLING
SLOWLY, WILL ISSUE FREEZING RAIN ADVISORY AREA SOUTH OF ICE STORM
WARNING A COUPLE TIERS OF COUNTIES. EXPECT ICING IN THIS AREA WILL
MAINLY BE ON ELEVATED SURFACES, BUT STILL COULD BE SUFFICIENT TO
CAUSE SOME PROBLEMS.
&&
.UPDATE...
EVE RAOB/TAMDAR SOUNDINGS SHOWING WARM LAYER OF GENERALLY +2 TO +6C
OVER OUR AREA RESULTING IN INITIAL PRECIP REACHING THE GROUND AS
RN/ZR. SFC OBS AND CALLS TO POLICE IN THE AREA INDICATE SO FAR ONLY
PATCHY REPORTS OF GLAZING IN NRN INDIANA AND NW OH EVEN THOUGH SOME
ASOS/AWOS SITES REPORTING TEMPS AT FREEZING. THIS PRBLY A RESULT OF
TEMPERATURE OF HEAVY RAINFALL GENERALLY REACHING THE GROUND ABOVE
FREEZING. IN MICHIGAN WHERE SFC TEMPS HAVE BEEN RUNNING A DEGREE OR
TWO BELOW FREEZING ALL DAY AND THIS EVE, MORE WIDESPREAD GLAZING IS
BEING REPORTED. WITH WAA OVERNIGHT AS SFC LOW MOVES NE FROM SRN MO
TO WEST CENTRAL OH, THE RN/SN LINE, WHICH IS EXPECTED TO SETUP FROM
JUST NORTH OF CHICAGO TO JUST NORTH OF DETROIT THIS EVE, WILL PRBLY
SHIFT SLIGHTLY NORTH. THUS, AS IN GOING FCST STILL EXPECTING A
MAINLY LIQUID EVENT WITH MAIN THREAT FOR ICE ACCUMULATIONS ACROSS
OUR NRN COUNTIES. MAIN QUESTIONS ARE HOW MUCH OF THE HEAVY RAIN WILL
ACCUMULATE AS ICE IN THE ADVISORY AREAS AND IF SFC TEMPS WILL FALL
SUFFICIENTLY SOUTH OF THE ADVISORY AREA TO WARRANT EXPANSION. FOR
NOW FEEL THINGS ARE ON TRACK AND WILL CONTINUE TO MONITOR BUT NO
CHANGES TO HEADLINES OR FCSTS PLANNED THIS EVE.
&&
.AVIATION...
ONLY MINOR CHANGES TO PREVIOUS TAFS. AREA OF LOW PRESSURE DVLPG OVER
SWRN MO THIS EVE WAS CAUSING OVER-RUNNING PRECIP TO DVLP NORTH OF
STNRY FRONT ALONG OH RVR. THIS SHOULD SPREAD INTO NRN INDIANA OVER
THE NEXT COUPLE OF HOURS WITH HEAVIEST RAINFALL INITIALLY MOVG INTO
THE FWA AREA. CIGS/VSBYS WERE ALREADY LOWERING IN ADVANCE OF THE
RAINFALL THIS EVE APPARENTLY IN RESPONSE TO DIURNAL COOLING OF THE
VERY MOIST LOW LEVELS. TEMPS EXPECTED TO REMAIN JUST COLD ENOUGH FOR
FREEZING RAIN AT SBN AND JUST WARM ENOUGH FOR RAIN NOT TO FREEZE AT
FWA AS THE LOW MOVES NE ACROSS SRN INDIANA TONIGHT. PRECIP INTENSITY
SHOULD DIMINISH ON MONDAY AS MID LEVEL DRY SLOT MOVES OVER THE AREA.
WITH COLD AIR WRAPPING AROUND THE LOW AS IT DEPARTS THE AREA TO OUR
EAST ON MONDAY, PRECIP SHOULD CHANGE OVER TO SNOW AT SBN EARLY IN
THE AFTN. POTENTIAL FOR LAKE ENHANCEMENT TO INTENSIFY SNOWFALL LATE
AFTN BUT SINCE NEAR END OF TAF PD DID NOT ADD TO TAFS YET. LIKEWISE
AT FWA COLDER AIR FILLING IN BEHIND THE LOW COULD CHANGE PRECIP TO
-ZL OR -SN LATE IN THE AFTN BUT HELD OFF MENTIONING THIS CHANGE IN
THE TAF FOR NOW.
&&
.SHORT TERM...
TONIGHT AND MONDAY.
...SIGNIFICANT ICING EXPECTED ACROSS SOUTHERN LOWER MICHIGAN TONIGHT
INTO MONDAY MORNING...
...SOME ICING EXPECTED ACROSS NORTHERN INDIANA AND NORTHWEST OHIO
TONIGHT AND MONDAY...
12Z NAM-WRF AND 12Z GFS CONTINUE TO TREND NEXT WAVE OF LOW PRESSURE
FARTHER NORTHWEST. THE NAM-WRF IS THE FARTHEST NORTHWEST OF THE
TWO...PLACING THE WAVE OF LOW PRESSURE OVER NW OHIO BY 12Z MONDAY.
BASED ON THE TREND OF BRINGING THE LOW FARTHER NORTHWEST...FEEL MORE
INCLINED TO SIDE WITH THE NAM-WRF AND THUS WILL USE ITS SOLUTION AS
A BACKBONE TO THE SHORT TERM FORECAST. ITS WARMER THERMAL PROFILE
WILL RESULT IN MOSTLY FREEZING RAIN TONIGHT ACRS THE NRN CWFA.
AT 20Z...LOW PRESSURE WAS DEVELOPING ALONG A STATIONARY FRONT OVER
NW ARKANSAS. AS A STRONG S/WV AND JET PIVOT NORTHEAST INTO THE
CNTRL PLAINS TONIGHT AND THEN INTO THE WRN GREAT LAKES ON
MONDAY...THE LOW WILL MOVE NORTHEAST AND DEEPEN WITH TIME...BEING
LOCATED NEAR SW INDIANA AT 06Z MONDAY AND NEAR NW OHIO BY 12Z MONDAY.
THE LOW WILL BE ASSOCIATED WITH STRONG...MOIST LOW LVL WARM
ADVECTION. THIS STRONG ASCENT WILL TEAM UP WITH UPR LVL DIVERGENCE
FROM A STRONG JET ALOFT. THIS WILL RESULT IN WIDESPREAD PCPN ACRS
THE CWFA OVERNIGHT. IN FACT...LATEST MOSAIC RADAR WAS SHOWING A
LARGE AREA OF PCPN BLOSSOMING ACRS THE CNTRL AND SRN PLAINS. THIS
PCPN WILL CONTINUE TO EXPAND AND MOVE NE INTO THE REGION TONIGHT.
THERE IS A LOT TO BE CONCERNED ABOUT OVERNIGHT INTO THE FIRST PART
OF MONDAY AS COLD AIR REMAINS TRAPPED NEAR THE SFC ACRS THE FAR NRN
CWFA. LATEST OBSERVATIONS SHOW TEMPS HOVERING BETWEEN 30 AND 33
DEGREES ACRS FAR NRN INDIANA...SOUTHERN LOWER MICHIGAN AND FAR
NORTHWEST OHIO. THESE TEMPS WILL NOT BUDGE MUCH OVERNIGHT...AND MAY
SLIGHTLY DROP A DEGREE OR TWO. FOR THE REMAINDER OF THE
REGION...TEMPS WILL REMAIN STEADY STATE IN THE LOWER TO MID
30S...EXPECT FOR THE FAR SOUTHEAST WHERE WARMER AIR WILL BE PULLED
WESTWARD AS THE LOW APPROACHES. WITH ABOUT THREE QUARTERS TO
AROUND ONE INCH OF QPF EXPECTED OVERNIGHT...SIGNIFICANT ICING WILL
OCCUR ACRS THE MICHIGAN COUNTIES WHERE ABOUT A HALF INCH OF ICE
ACCUMULATION IS EXPECTED. FOR THE FAR NRN INDIANA AND NORTHWEST
OHIO COUNTIES...ICE ACCUMULATIONS WILL BE LESS THAN A QUARTER INCH.
FARTHER SOUTH...MAINLY RAIN IS EXPECTED. AN ICE STORM WARNING WILL
BE ISSUED FOR THE MICHIGAN COUNTIES UNTIL 17Z MONDAY...WHILE A
FREEZING RAIN ADVISORY WILL BE ISSUED FOR THE FAR NRN INDIANA/NW
OHIO COUNTIES THROUGH 17Z MONDAY. ADDITIONAL RAINFALL ACRS THE FAR
SOUTH/SOUTHEAST WILL LIKELY LEAD TO RIVER FLOODING ALONG THE UPPER
WABASH AND MAUMEE RIVER BASINS..SO WILL MAINTAIN FLOOD WATCH FOR
THIS LOCATION THROUGH 18Z MONDAY.
ON MONDAY...AS SFC LOW PRESSURE PULLS AWAY TO THE NE...COLDER AIR
WILL BEGIN TO FILTER SE INTO THE FCST AREA. THERE WILL LIKELY BE
FREEZING PCPN ACRS THE NW HALF OF THE CWFA...BUT THIS SHOULD BE ON
THE LIGHT SIDE. FOR THE SOUTHEAST...LIGHT RAIN IS EXPECTED. MODELS
CONTINUE TO SHOW A DRY SLOT WORKING INTO THE REGION BY MID MORNING.
THIS MAY CHC PCPN TO DRIZZLE OR FREEZING DRIZZLE. HAVE OPTED TO GO
WITH THE LIGHT FREEZING RAIN/LIGHT RAIN WORDING DUE TO LINGER PCPN
EARLY IN THE MORNING IN ASSOCIATION WITH THE LOW AND FOR THE FACT
THAT SOME OF THE DRIZZLE MAY MEASURE. AS COLDER AIR AND DEEPER
ATMOSPHERIC MOISTURE FILTER INTO THE REGION DURING THE
AFTERNOON...ANY DRIZZLE WILL CHANGEOVER TO SOME LIGHT SNOW. MAIN
LAKE EFFECT EVENT LOOKS TO HOLD OFF UNTIL MONDAY NIGHT AND WILL
LEAVE THOSE DETAILS TO THE LONG TERM FORECASTER.
&&
.LONG TERM...
MONDAY NIGHT THROUGH SUNDAY
...SIGNIFICANT LAKE EFFECT SNOW POSSIBLE MONDAY NIGHT THROUGH
TUESDAY...
MAIN CONCERN FOR THE LONG TERM TODAY REVOLVES AROUND LAKE EFFECT
POTENTIAL AT THE START OF THE PERIOD. MODERATE LOW/MID LEVEL CAA
FOLLOWING MAJOR FRONTAL WAVE ON MON WILL BRING MUCH COLDER AIR
ACROSS THE LAKE WITH AMPLE LAKE INSTABILITY DEVELOPING. NEAR RECORD
WARM LAKE TEMPERATURE OF AROUND 5C PER LATEST SATELLITE DERIVED DATA
WILL CONTRIBUTE TO MODERATE COLLIER INDEX WITH LAKE INDUCED CAPE
AROUND 500J/KG AND LAKE INDUCED EQUILIBRIUM LEVELS AROUND 10K FEET.
INSTABILITY IS CERTAINLY MORE THAN AMPLE...HOWEVER MUCH UNCERTAINTY
LIES WITH BAND MODE...PLACEMENT...AND AMOUNT OF SHEAR. FROM A
PATTERN RECOGNITION PROSPECTIVE...SETUP LOOKS VERY FAVORABLE WITH A
1040+MB HIGH BUILDING SOUTH THROUGH THE PLAINS AND FAVORABLE N/NNW
FLOW DEVELOPING DOWN A SUBSTANTIAL FETCH OF LAKE MICHIGAN. A
POTENTIAL NEGATIVE...BOTH NAM/GFS SUGGEST THERE WILL BE SOME SHEAR
NEAR THE TOP OF THE LAKE INDUCED MIXED LAYER WITH A MORE WESTERLY
COMPONENT AT 700MB AND MORE NW/NNW AT 850MB. NAM-WRF PLUME ANALYSIS
CONTINUES TO SUGGEST THE POTENTIAL FOR A TYPE I LAKE EFFECT
BAND...MEANING A DOMINANT BAND PARALLEL TO THE MAJOR AXIS OF THE
LAKE.
NAM-WRF HAS BEEN FLIP-FLOPPING WILDLY FROM RUN TO RUN WITH RESPECT
TO DIRECTION OF LOW LEVEL FLOW...WITH 00Z AND 06Z RUNS SUGGESTING A
NEAR DUE NORTH FETCH...WHILE 12Z RUN SUGGESTS MORE NW FETCH. A LOOK
AT SOME OTHER MESOSCALE GUIDANCE SUCH AS THE FSL EXPERIMENTAL RUC
AND THE CANADIAN GEM SHOW MORE UNCERTAINTY...WITH BOTH THOSE MODELS
DEPICTING MORE NORTHERLY FLOW AND A MORE WESTWARD BAND PLACEMENT.
TYPICAL BIAS OF MESOSCALE MODELS ARE TO BE TOO FAR WEST WITH A
DOMINANT BAND AT THE SOUTHERN END OF LAKE MICHIGAN. WITH THE VERY
POOR MODEL AGREEMENT AND CONSISTENCY...JUST NOT ENOUGH CONFIDENCE
ON BAND PLACEMENT OR MODE TO GO WITH AN LES WATCH YET. STILL ENOUGH
TIME FOR A SHORTER RANGE WATCH FROM THE MIDNIGHT SHIFT IF MODEL
GUIDANCE STARTS TO CONVERGE ON A COMMON SOLUTION. THIS DOES HAVE THE
POTENTIAL TO BE A MAJOR EVENT GIVEN STRONG THERMODYNAMICS...BUT ONLY
IF A DOMINANT BAND FORMS...AND THAT IS STILL QUITE UNCERTAIN.
CP SURFACE HIGH BUILDS ACROSS THE OHIO VALLEY LATER TUE NGT INTO WED
WITH CRASHING INVERSION HEIGHTS AND BACKING LOW LEVEL FLOW CUTTING
OFF ANY REMAINING LAKE EFFECT. SHOULD SEE A DRY PERIOD FOR WED AND
THU WITH A MODERATING TREND AS HEIGHTS RISE IN RESPONSE TO DIGGING
UPSTREAM TROUGH. VERY LITTLE CHANGE MADE TO CONTINUITY IN THE LATER
PERIODS WITH PRIMARY CONCERNS IN SHORT TERM HIGH IMPACT WEATHER.
STILL APPEARS THAT ONE OR SEVERAL CLIPPER TYPE SHORTWAVES WILL CROSS
THE GREAT LAKES STARTING AT THE END OF THE WEEK AND HAVE CONTINUED
WITH LOW CHANCE POPS...MAINLY ACROSS THE NORTHERN PORTION OF THE
CWA. TEMPS WILL AVERAGE AROUND NORMAL FOR MUCH OF THE LONG TERM...
BUT THIS WILL FEEL COLD AFTER THE INCREDIBLE STRETCH OF WARM WEATHER
THE PAST MONTH.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...FLOOD WATCH THROUGH MONDAY AFTERNOON FOR INZ020-INZ022-INZ023-
INZ024-INZ025-INZ026-INZ027-INZ032-INZ033-INZ034.
FREEZING RAIN ADVISORY UNTIL 12 PM EST /11 AM CST/ MONDAY FOR
INZ008-INZ009-INZ012-INZ013-INZ014-INZ015-INZ016-INZ017-
INZ018.
ICE STORM WARNING UNTIL 12 PM EST /11 AM CST/ MONDAY FOR INZ003-
INZ004-INZ005-INZ006-INZ007.
MI...ICE STORM WARNING UNTIL 12 PM EST MONDAY FOR MIZ077-MIZ078-
MIZ079-MIZ080-MIZ081.
OH...FLOOD WATCH THROUGH MONDAY AFTERNOON FOR OHZ016-OHZ024-OHZ025.
FREEZING RAIN ADVISORY UNTIL 12 PM EST MONDAY FOR OHZ004-OHZ005-
OHZ015.
ICE STORM WARNING UNTIL 12 PM EST MONDAY FOR OHZ001-OHZ002.
LM...SMALL CRAFT ADVISORY UNTIL 5 PM EST TUESDAY FOR LMZ043-LMZ046.
$$
AVIATION/UPDATE...TAYLOR
SHORT TERM...HICKMAN
LONG TERM....HITCHCOCK
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
AFDIWX 937 PM EST SUN JAN 14 2007
.UPDATE...
EVE RAOB/TAMDAR SOUNDINGS SHOWING WARM LAYER OF GENERALLY +2 TO +6C
OVER OUR AREA RESULTING IN INITIAL PRECIP REACHING THE GROUND AS
RN/ZR. SFC OBS AND CALLS TO POLICE IN THE AREA INDICATE SO FAR ONLY
PATCHY REPORTS OF GLAZING IN NRN INDIANA AND NW OH EVEN THOUGH SOME
ASOS/AWOS SITES REPORTING TEMPS AT FREEZING. THIS PRBLY A RESULT OF
TEMPERATURE OF HEAVY RAINFALL GENERALLY REACHING THE GROUND ABOVE
FREEZING. IN MICHIGAN WHERE SFC TEMPS HAVE BEEN RUNNING A DEGREE OR
TWO BELOW FREEZING ALL DAY AND THIS EVE, MORE WIDESPREAD GLAZING IS
BEING REPORTED. WITH WAA OVERNIGHT AS SFC LOW MOVES NE FROM SRN MO
TO WEST CENTRAL OH, THE RN/SN LINE, WHICH IS EXPECTED TO SETUP FROM
JUST NORTH OF CHICAGO TO JUST NORTH OF DETROIT THIS EVE, WILL PRBLY
SHIFT SLIGHTLY NORTH. THUS, AS IN GOING FCST STILL EXPECTING A
MAINLY LIQUID EVENT WITH MAIN THREAT FOR ICE ACCUMULATIONS ACROSS
OUR NRN COUNTIES. MAIN QUESTIONS ARE HOW MUCH OF THE HEAVY RAIN WILL
ACCUMULATE AS ICE IN THE ADVISORY AREAS AND IF SFC TEMPS WILL FALL
SUFFICIENTLY SOUTH OF THE ADVISORY AREA TO WARRANT EXPANSION. FOR
NOW FEEL THINGS ARE ON TRACK AND WILL CONTINUE TO MONITOR BUT NO
CHANGES TO HEADLINES OR FCSTS PLANNED THIS EVE.
&&
.AVIATION...
ONLY MINOR CHANGES TO PREVIOUS TAFS. AREA OF LOW PRESSURE DVLPG OVER
SWRN MO THIS EVE WAS CAUSING OVER-RUNNING PRECIP TO DVLP NORTH OF
STNRY FRONT ALONG OH RVR. THIS SHOULD SPREAD INTO NRN INDIANA OVER
THE NEXT COUPLE OF HOURS WITH HEAVIEST RAINFALL INITIALLY MOVG INTO
THE FWA AREA. CIGS/VSBYS WERE ALREADY LOWERING IN ADVANCE OF THE
RAINFALL THIS EVE APPARENTLY IN RESPONSE TO DIURNAL COOLING OF THE
VERY MOIST LOW LEVELS. TEMPS EXPECTED TO REMAIN JUST COLD ENOUGH FOR
FREEZING RAIN AT SBN AND JUST WARM ENOUGH FOR RAIN NOT TO FREEZE AT
FWA AS THE LOW MOVES NE ACROSS SRN INDIANA TONIGHT. PRECIP INTENSITY
SHOULD DIMINISH ON MONDAY AS MID LEVEL DRY SLOT MOVES OVER THE AREA.
WITH COLD AIR WRAPPING AROUND THE LOW AS IT DEPARTS THE AREA TO OUR
EAST ON MONDAY, PRECIP SHOULD CHANGE OVER TO SNOW AT SBN EARLY IN
THE AFTN. POTENTIAL FOR LAKE ENHANCEMENT TO INTENSIFY SNOWFALL LATE
AFTN BUT SINCE NEAR END OF TAF PD DID NOT ADD TO TAFS YET. LIKEWISE
AT FWA COLDER AIR FILLING IN BEHIND THE LOW COULD CHANGE PRECIP TO
-ZL OR -SN LATE IN THE AFTN BUT HELD OFF MENTIONING THIS CHANGE IN
THE TAF FOR NOW.
&&
.SHORT TERM...
TONIGHT AND MONDAY.
...SIGNIFICANT ICING EXPECTED ACROSS SOUTHERN LOWER MICHIGAN TONIGHT
INTO MONDAY MORNING...
...SOME ICING EXPECTED ACROSS NORTHERN INDIANA AND NORTHWEST OHIO
TONIGHT AND MONDAY...
12Z NAM-WRF AND 12Z GFS CONTINUE TO TREND NEXT WAVE OF LOW PRESSURE
FARTHER NORTHWEST. THE NAM-WRF IS THE FARTHEST NORTHWEST OF THE
TWO...PLACING THE WAVE OF LOW PRESSURE OVER NW OHIO BY 12Z MONDAY.
BASED ON THE TREND OF BRINGING THE LOW FARTHER NORTHWEST...FEEL MORE
INCLINED TO SIDE WITH THE NAM-WRF AND THUS WILL USE ITS SOLUTION AS
A BACKBONE TO THE SHORT TERM FORECAST. ITS WARMER THERMAL PROFILE
WILL RESULT IN MOSTLY FREEZING RAIN TONIGHT ACRS THE NRN CWFA.
AT 20Z...LOW PRESSURE WAS DEVELOPING ALONG A STATIONARY FRONT OVER
NW ARKANSAS. AS A STRONG S/WV AND JET PIVOT NORTHEAST INTO THE
CNTRL PLAINS TONIGHT AND THEN INTO THE WRN GREAT LAKES ON
MONDAY...THE LOW WILL MOVE NORTHEAST AND DEEPEN WITH TIME...BEING
LOCATED NEAR SW INDIANA AT 06Z MONDAY AND NEAR NW OHIO BY 12Z MONDAY.
THE LOW WILL BE ASSOCIATED WITH STRONG...MOIST LOW LVL WARM
ADVECTION. THIS STRONG ASCENT WILL TEAM UP WITH UPR LVL DIVERGENCE
FROM A STRONG JET ALOFT. THIS WILL RESULT IN WIDESPREAD PCPN ACRS
THE CWFA OVERNIGHT. IN FACT...LATEST MOSAIC RADAR WAS SHOWING A
LARGE AREA OF PCPN BLOSSOMING ACRS THE CNTRL AND SRN PLAINS. THIS
PCPN WILL CONTINUE TO EXPAND AND MOVE NE INTO THE REGION TONIGHT.
THERE IS A LOT TO BE CONCERNED ABOUT OVERNIGHT INTO THE FIRST PART
OF MONDAY AS COLD AIR REMAINS TRAPPED NEAR THE SFC ACRS THE FAR NRN
CWFA. LATEST OBSERVATIONS SHOW TEMPS HOVERING BETWEEN 30 AND 33
DEGREES ACRS FAR NRN INDIANA...SOUTHERN LOWER MICHIGAN AND FAR
NORTHWEST OHIO. THESE TEMPS WILL NOT BUDGE MUCH OVERNIGHT...AND MAY
SLIGHTLY DROP A DEGREE OR TWO. FOR THE REMAINDER OF THE
REGION...TEMPS WILL REMAIN STEADY STATE IN THE LOWER TO MID
30S...EXPECT FOR THE FAR SOUTHEAST WHERE WARMER AIR WILL BE PULLED
WESTWARD AS THE LOW APPROACHES. WITH ABOUT THREE QUARTERS TO
AROUND ONE INCH OF QPF EXPECTED OVERNIGHT...SIGNIFICANT ICING WILL
OCCUR ACRS THE MICHIGAN COUNTIES WHERE ABOUT A HALF INCH OF ICE
ACCUMULATION IS EXPECTED. FOR THE FAR NRN INDIANA AND NORTHWEST
OHIO COUNTIES...ICE ACCUMULATIONS WILL BE LESS THAN A QUARTER INCH.
FARTHER SOUTH...MAINLY RAIN IS EXPECTED. AN ICE STORM WARNING WILL
BE ISSUED FOR THE MICHIGAN COUNTIES UNTIL 17Z MONDAY...WHILE A
FREEZING RAIN ADVISORY WILL BE ISSUED FOR THE FAR NRN INDIANA/NW
OHIO COUNTIES THROUGH 17Z MONDAY. ADDITIONAL RAINFALL ACRS THE FAR
SOUTH/SOUTHEAST WILL LIKELY LEAD TO RIVER FLOODING ALONG THE UPPER
WABASH AND MAUMEE RIVER BASINS..SO WILL MAINTAIN FLOOD WATCH FOR
THIS LOCATION THROUGH 18Z MONDAY.
ON MONDAY...AS SFC LOW PRESSURE PULLS AWAY TO THE NE...COLDER AIR
WILL BEGIN TO FILTER SE INTO THE FCST AREA. THERE WILL LIKELY BE
FREEZING PCPN ACRS THE NW HALF OF THE CWFA...BUT THIS SHOULD BE ON
THE LIGHT SIDE. FOR THE SOUTHEAST...LIGHT RAIN IS EXPECTED. MODELS
CONTINUE TO SHOW A DRY SLOT WORKING INTO THE REGION BY MID MORNING.
THIS MAY CHC PCPN TO DRIZZLE OR FREEZING DRIZZLE. HAVE OPTED TO GO
WITH THE LIGHT FREEZING RAIN/LIGHT RAIN WORDING DUE TO LINGER PCPN
EARLY IN THE MORNING IN ASSOCIATION WITH THE LOW AND FOR THE FACT
THAT SOME OF THE DRIZZLE MAY MEASURE. AS COLDER AIR AND DEEPER
ATMOSPHERIC MOISTURE FILTER INTO THE REGION DURING THE
AFTERNOON...ANY DRIZZLE WILL CHANGEOVER TO SOME LIGHT SNOW. MAIN
LAKE EFFECT EVENT LOOKS TO HOLD OFF UNTIL MONDAY NIGHT AND WILL
LEAVE THOSE DETAILS TO THE LONG TERM FORECASTER.
&&
.LONG TERM...
MONDAY NIGHT THROUGH SUNDAY
...SIGNIFICANT LAKE EFFECT SNOW POSSIBLE MONDAY NIGHT THROUGH
TUESDAY...
MAIN CONCERN FOR THE LONG TERM TODAY REVOLVES AROUND LAKE EFFECT
POTENTIAL AT THE START OF THE PERIOD. MODERATE LOW/MID LEVEL CAA
FOLLOWING MAJOR FRONTAL WAVE ON MON WILL BRING MUCH COLDER AIR
ACROSS THE LAKE WITH AMPLE LAKE INSTABILITY DEVELOPING. NEAR RECORD
WARM LAKE TEMPERATURE OF AROUND 5C PER LATEST SATELLITE DERIVED DATA
WILL CONTRIBUTE TO MODERATE COLLIER INDEX WITH LAKE INDUCED CAPE
AROUND 500J/KG AND LAKE INDUCED EQUILIBRIUM LEVELS AROUND 10K FEET.
INSTABILITY IS CERTAINLY MORE THAN AMPLE...HOWEVER MUCH UNCERTAINTY
LIES WITH BAND MODE...PLACEMENT...AND AMOUNT OF SHEAR. FROM A
PATTERN RECOGNITION PROSPECTIVE...SETUP LOOKS VERY FAVORABLE WITH A
1040+MB HIGH BUILDING SOUTH THROUGH THE PLAINS AND FAVORABLE N/NNW
FLOW DEVELOPING DOWN A SUBSTANTIAL FETCH OF LAKE MICHIGAN. A
POTENTIAL NEGATIVE...BOTH NAM/GFS SUGGEST THERE WILL BE SOME SHEAR
NEAR THE TOP OF THE LAKE INDUCED MIXED LAYER WITH A MORE WESTERLY
COMPONENT AT 700MB AND MORE NW/NNW AT 850MB. NAM-WRF PLUME ANALYSIS
CONTINUES TO SUGGEST THE POTENTIAL FOR A TYPE I LAKE EFFECT
BAND...MEANING A DOMINANT BAND PARALLEL TO THE MAJOR AXIS OF THE
LAKE.
NAM-WRF HAS BEEN FLIP-FLOPPING WILDLY FROM RUN TO RUN WITH RESPECT
TO DIRECTION OF LOW LEVEL FLOW...WITH 00Z AND 06Z RUNS SUGGESTING A
NEAR DUE NORTH FETCH...WHILE 12Z RUN SUGGESTS MORE NW FETCH. A LOOK
AT SOME OTHER MESOSCALE GUIDANCE SUCH AS THE FSL EXPERIMENTAL RUC
AND THE CANADIAN GEM SHOW MORE UNCERTAINTY...WITH BOTH THOSE MODELS
DEPICTING MORE NORTHERLY FLOW AND A MORE WESTWARD BAND PLACEMENT.
TYPICAL BIAS OF MESOSCALE MODELS ARE TO BE TOO FAR WEST WITH A
DOMINANT BAND AT THE SOUTHERN END OF LAKE MICHIGAN. WITH THE VERY
POOR MODEL AGREEMENT AND CONSISTENCY...JUST NOT ENOUGH CONFIDENCE
ON BAND PLACEMENT OR MODE TO GO WITH AN LES WATCH YET. STILL ENOUGH
TIME FOR A SHORTER RANGE WATCH FROM THE MIDNIGHT SHIFT IF MODEL
GUIDANCE STARTS TO CONVERGE ON A COMMON SOLUTION. THIS DOES HAVE THE
POTENTIAL TO BE A MAJOR EVENT GIVEN STRONG THERMODYNAMICS...BUT ONLY
IF A DOMINANT BAND FORMS...AND THAT IS STILL QUITE UNCERTAIN.
CP SURFACE HIGH BUILDS ACROSS THE OHIO VALLEY LATER TUE NGT INTO WED
WITH CRASHING INVERSION HEIGHTS AND BACKING LOW LEVEL FLOW CUTTING
OFF ANY REMAINING LAKE EFFECT. SHOULD SEE A DRY PERIOD FOR WED AND
THU WITH A MODERATING TREND AS HEIGHTS RISE IN RESPONSE TO DIGGING
UPSTREAM TROUGH. VERY LITTLE CHANGE MADE TO CONTINUITY IN THE LATER
PERIODS WITH PRIMARY CONCERNS IN SHORT TERM HIGH IMPACT WEATHER.
STILL APPEARS THAT ONE OR SEVERAL CLIPPER TYPE SHORTWAVES WILL CROSS
THE GREAT LAKES STARTING AT THE END OF THE WEEK AND HAVE CONTINUED
WITH LOW CHANCE POPS...MAINLY ACROSS THE NORTHERN PORTION OF THE
CWA. TEMPS WILL AVERAGE AROUND NORMAL FOR MUCH OF THE LONG TERM...
BUT THIS WILL FEEL COLD AFTER THE INCREDIBLE STRETCH OF WARM WEATHER
THE PAST MONTH.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH MONDAY AFTERNOON
FOR INZ020-INZ022-INZ023-INZ024-INZ025-INZ026-INZ027-INZ032-
INZ033-INZ034.
FREEZING RAIN ADVISORY UNTIL 12 PM EST /11 AM CST/ MONDAY FOR
INZ003-INZ004-INZ005-INZ006-INZ007.
MI...ICE STORM WARNING UNTIL 12 PM EST MONDAY FOR MIZ077-MIZ078-
MIZ079-MIZ080-MIZ081.
OH...FLOOD WATCH FROM 7 PM EST THIS EVENING THROUGH MONDAY AFTERNOON
FOR OHZ016-OHZ024-OHZ025.
FREEZING RAIN ADVISORY UNTIL 12 PM EST MONDAY FOR OHZ001-OHZ002.
LM...SMALL CRAFT ADVISORY FROM MIDNIGHT EST UNTIL 5PM EST TUESDAY
FOR LMZ043-LMZ046.
&&
$$
AVIATION/UPDATE...TAYLOR
SHORT TERM...HICKMAN
LONG TERM....HITCHCOCK
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
AFDIWX 330 PM EST SAT JAN 13 2007
.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/AVIATION...HICKMAN
LONG TERM....HITCHCOCK
AREA FORECAST DISCUSSION
NWS WICHITA KS
AFDICT 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 11 16 10 19 / 40 100 30 10
HUTCHINSON 10 15 9 18 / 40 100 40 10
NEWTON 10 16 9 18 / 30 100 40 10
ELDORADO 11 17 10 19 / 40 100 40 10
WINFIELD-KWLD 14 19 11 20 / 50 100 20 0
RUSSELL 9 15 7 16 / 40 100 60 10
GREAT BEND 10 15 8 16 / 40 100 50 10
SALINA 10 15 8 17 / 30 100 60 10
MCPHERSON 10 15 9 17 / 30 100 50 10
COFFEYVILLE 17 23 14 22 / 60 100 30 10
CHANUTE 15 21 13 21 / 60 100 30 10
IOLA 14 20 13 20 / 60 100 30 10
PARSONS-KPPF 16 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 1016 AM EST SAT JAN 13 2007
.MORNING UPDATE (THIS AFTERNOON/TONIGHT)...
CURRENT MORNING SFC ANALYSIS REVEALS COLD FRONT FROM NEAR CMH SW TO
JUST WEST OF MEM. PRETTY GOOD TEMPERATURE GRADIENT NOTED ACROSS THE
FAR NW PORTION OF THE DISTRICT WITH READINGS IN THE MID AND UPPER
50S ACROSS MUCH OF THE FA...BUT UP NEAR JASPER TEMPERATURES HAVE
DROPPED INTO THE MID 40S. AREA RADARS SHOWING NEXT ROUND OF LIGHT
TO MODERATE RAIN MOVING IN FROM THE WEST WHICH WILL PASS THROUGH THE
FA THIS AFTERNOON. EASTERN SECTIONS WILL SEE A GENERAL DOWNWARD
TREND IN PRECIPITATION LATE THIS MORNING BEFORE INCREASING AGAIN IN
THE AFTERNOON.
LOOKING AT THE LATEST SHORT TERM GUIDANCE...THE RUC MODELS
(13KM/40KM) SEEM TO HAVE A VERY GOOD HANDLE ON TEMPERATURES THIS
MORNING. THE RUC MODELS SEEM TO BRING THE FRONT TO ABOUT LOUISVILLE
LATE THIS EVENING AND THEN STALLING IT OUT. THE NET RESULT WOULD BE
TEMPERATURES ACROSS OUR SOUTHERN INDIANA COUNTIES WOULD FALL DURING
THE AFTERNOON INTO THE MID AND UPPER 40S WITH ALL OF THE KY COUNTIES
TEMPERATURES HOLDING STEADY IN THE MID TO UPPER 50S.
CURRENT FORECAST IS GOOD SHAPE RIGHT NOW...BUT WILL NEED TO MAKE
SOME MINOR ADJUSTMENTS TO THE TEMP GRIDS TO REFLECT CURRENT RUC
TRENDS.
ON THE HYDROLOGICAL SIDE...AT THE PRESENT TIME WE ARE IN GOOD
SHAPE. THE LIGHT TO MODERATE RAINS THUS FAR HAVE NOT RESULTED IN
EXCESSIVE RUNOFF. HOWEVER...MAIN BULK OF PRECIPITATION ACCUMULATION
IS FORECAST TO IMPACT THE REGION LATE TONIGHT AND ON SUNDAY.
THEREFORE...CURRENT FLOOD WATCH WILL REMAIN IN EFFECT.
UPDATED FORECAST SUITE WILL BE AVAILABLE BY 1100 AM EST.
-MJ
PREVIOUS DISCUSSION FOLLOWS...
.SHORT TERM (TODAY AND TONIGHT)...
CURRENTLY...DEEP SWRLY FLOW IS DOMINATING ACROSS THE REGION. A COLD
FRONT IS QUICKLY APPROACHING FROM THE WEST AND IS PUSHING THROUGH
EVV ATTM. LOW-LEVEL COLD AIR IS FILTERING IN BEHIND THE FRONT FASTER
THAN MODELS HAD ANTICIPATED. LARGE AMOUNT OF ISENTROPIC LIFT OVER
THE COLD AIR HAS LED TO QUITE AN ICING EVENT OVER PORTIONS OF OK
INTO MO. LARGE TEMP GRADIENT PRESENT AS WELL...AS PAH WAS AT 60
DEGREES AND CAPE GIRARDEAU AT 39 DEGREES AT 2AM EST.
DESPITE COLD FRONT QUICKLY APPROACHING...A LOW PRESSURE WAVE OVER
THE TEXARKANA REGION RIDING NEWD ALONG THE FRONT WILL HELP SLOW THE
FRONT`S PROGRESSION...AND WILL BE RESPONSIBLE FOR OUR FIRST WAVE OF
POTENTIALLY HEAVY PRECIP...WHICH IS CURRENTLY OVER WRN KY. THIS AREA
SHOULD EXPAND AND FILTER INTO OUR CWA THROUGHOUT THE MORNING. MAY
EVEN SEE A RUMBLE OF THUNDER OR TWO WITH THIS FIRST BATCH OF
RAINFALL GIVEN UPSTREAM TRENDS. WILL ONLY MENTION ISLD THREAT WEST
OF I-65 THIS MORNING. AFTER THIS MORNING`S MAIN AREA OF PRECIP...A
LULL IN THE PRECIP SHOULD OCCUR THIS AFTERNOON BEFORE ANOTHER LOW
PRESSURE WAVE RIDES NEWD ALONG THE FRONT TONIGHT...CAUSING ANOTHER
BOUT OF POTENTIALLY HEAVY RAIN.
THOUGH RAIN ONSET IS LATER THAN ANTICIPATED...STILL THINK THE FLOOD
WATCH IS WARRANTED THROUGH THE WEEKEND. PWATS ARE OVER AN INCH
NOW...AND NAM BUFKIT SOUNDINGS INDICATE NEAR 1.5 INCHES THIS
EVENING...WHICH IS SUPPORTED BY THE 4-5 STD DEVIATIONS ABV NORMAL
POSED BY THE SHORT-RANGE ENSEMBLES. ALSO...NAM AND GFS INDICATE SOME
ELEVATED INSTABILITY WITH LI`S AROUND ZERO TONIGHT...WHICH WILL AID
IN OVERALL PRECIP AMOUNTS GIVEN THIS CONVECTION. STILL THINK SOME
LOCATIONS COULD SEE 2-3 INCHES OF RAINFALL...WITH ISOLATED LOCATIONS
SEEING 4 INCHES OR MORE. HOWEVER...GIVEN THE SLOW ONSET THINK A
WIDESPREAD FLOODING EVENT IS NOT LIKELY...THOUGH A MINOR AND MORE
ISOLATED FLOODING EVENT IS CERTAINLY POSSIBLE...SO WILL CONTINUE
FLOOD WATCH. MAY DOWN PLAY AMOUNTS A WEE BIT BUT THAT IS ALL.
THE FRONT WILL BE CLOSELY ALIGNED WITH THE OHIO RIVER AROUND SUNRISE
AND SHOULD BE IN NEARLY THE SAME LOCATION OR JUST SE BY MIDNIGHT
TONIGHT. WILL KEEP CATEGORICAL POPS GOING...WITH MENTION OF LOCALLY
HEAVY RAINFALL.
FOR AVIATION CONCERNS...HAVE LOW-LEVEL WIND SHEAR IN ALL THE TAF
SITES THIS MORNING GIVEN THE STRONG SWRLY JET OF 40-45 KTS OVER THE
CWA NOW...EVIDENT FROM AREA VWPS AND SDF ACARS SOUNDINGS. MAY SEE
SOME GUSTY WINDS HERE AND THERE...BUT NOTHING OUT OF HAND AS CLOUDY
SKIES SHOULD HELP INHIBIT LARGER GUSTS.
TEMPS WILL BE TRICKY TODAY...AND COULD HAVE QUITE THE GRADIENT
ACROSS THE CWA...ESPECIALLY BY MIDDAY. TEMPS MAY DROP AND/OR STEADY
OUT ACROSS THE NW...WITH CURRENT READINGS IN THE UPPER 50S DROPPING
TO THE UPPER 40S AND HOLDING THERE. THE SERN CWA COULD SEE HIGHS A
FEW DEGREES WARMER THAN CURRENT READINGS...AND SHOULD STICK AROUND
60 FOR THE MOST PART. OVERNIGHT LOWS WILL NOT BUDGE MUCH AND SHOULD
BE JUST A FEW DEGREES COLDER THAN HIGHS TODAY.
AL
.LONG TERM (SUNDAY THROUGH FRIDAY)...
SUNDAY AND MONDAY...
FORECAST CHALLENGE WILL BE PLACEMENT OF THE COLD FRONT AT THE
BEGINNING OF THIS PERIOD. LATEST SHORT RANGE MODELS DID NOT
INITIALIZE SHALLOW COLD AIR WELL AND FEEL IT WILL BE FURTHER SOUTH
THAN MODELS SUGGEST. SURFACE WAVE SHOULD SHIFT THE COLD AIR NORTH
SOME DURING THE AFTERNOON SUNDAY AND AT THIS TIME WE WILL KEEP
PRECIPITATION ACROSS THE NORTH IN THE FORM OF RAIN. THE AXIS OF
HEAVY RAIN SUNDAY AND SUNDAY NIGHT STILL LOOKS TO BE ALONG THE OHIO
RIVER WHERE AN INCH TO AN INCH AND A HALF WILL BE POSSIBLE. LIGHTEST
AMOUNTS WILL OCCUR ACROSS THE SOUTHEAST PORTION OF THE COUNTY
FORECAST AREA. WE WILL HOLD ONTO ISOLATED THUNDERSTORMS SOUTH OF THE
OHIO RIVER SUNDAY WHERE BEST DYNAMICS EXIST...ALTHOUGH INSTABILITY
WILL BE LACKING.
TEMPERATURES WILL BE A CONCERN AS WELL AS A 10 TO 15 DEGREE GRADIENT
WILL BE NOTED ACROSS THE COLD FRONT. HIGHS SUNDAY WILL TOP OUT IN
THE LOWER 40S ACROSS SOUTHERN INDIANA WITH UPPER 50S EXPECTED NEAR
THE TENNESSEE BORDER.
ONCE THE SURFACE LOW MOVES NORTHEAST OF THE REGION THE MODIFIED
ARCTIC AIR WILL ENTER THE FORECAST AREA MONDAY. HIGHEST TEMPERATURES
WILL OCCUR DURING THE MORNING. LIGHT SNOW SHOWERS WILL BE POSSIBLE
MONDAY BUT NO ACCUMULATION IS EXPECTED.
JA
TUESDAY THROUGH FRIDAY...
NOT MUCH CHANGE IN THE FORECAST THROUGH THIS TIME PERIOD. WITH
FRONT CONTINUING TO OUR SOUTH AND HIGH PRESSURE BUILDING IN FROM THE
UPPER PLAINS...NORTHERLY WINDS WILL GET THE LAKE-EFFECT SNOW MACHINE
GOING TO OUR NORTH. DOWN THIS FAR SOUTH...FEEL THAT SCT FLURRIES
WILL BE POSSIBLE DURING THE DAY ON TUESDAY AND WILL LEAVE AS SUCH.
BETTER CHC FOR SNOW SHOWERS WOULD EXIST OVER FAR EAST KY IN THE
FAVORED UPSLOPE REGIONS. DRY FORECAST IS ANTICIPATED FOR WEDNESDAY
THROUGH FRIDAY AS HIGH PRESSURE CONTINUES TO BUILD OVER THE REGION.
TEMPERATURES AT THE BEGINNING OF THIS PD WILL BE WELL BELOW NORMAL
WITH HIGHS IN THE UPPER 20S TO LOWER 30S AND OVERNIGHT LOWS IN THE
UPPER TEENS. SOME MODERATION IN THE TEMPERATURES WILL OCCUR BY
THURSDAY AND FRIDAY WITH TEMPERATURES WARMING SLIGHTLY INTO THE
MID AND UPPER 30S. GENERALLY STUCK CLOSE TO THE HPC GUIDANCE
THROUGH THIS PERIOD.
MJ
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...FLOOD WATCH THROUGH LATE SUNDAY NIGHT FOR KYZ023>043-045>049-
053>057-061>067-070>078-081-082.
IN...FLOOD WATCH THROUGH LATE SUNDAY NIGHT FOR INZ076>079-083-084-
089>092.
&&
$$
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
AFDLMK 259 AM EST SAT JAN 13 2007
.SHORT TERM (TODAY AND TONIGHT)...
CURRENTLY...DEEP SWRLY FLOW IS DOMINATING ACROSS THE REGION. A COLD
FRONT IS QUICKLY APPROACHING FROM THE WEST AND IS PUSHING THROUGH
EVV ATTM. LOW-LEVEL COLD AIR IS FILTERING IN BEHIND THE FRONT FASTER
THAN MODELS HAD ANTICIPATED. LARGE AMOUNT OF ISENTROPIC LIFT OVER
THE COLD AIR HAS LED TO QUITE AN ICING EVENT OVER PORTIONS OF OK
INTO MO. LARGE TEMP GRADIENT PRESENT AS WELL...AS PAH WAS AT 60
DEGREES AND CAPE GIRARDEAU AT 39 DEGREES AT 2AM EST.
DESPITE COLD FRONT QUICKLY APPROACHING...A LOW PRESSURE WAVE OVER
THE TEXARKANA REGION RIDING NEWD ALONG THE FRONT WILL HELP SLOW THE
FRONT`S PROGRESSION...AND WILL BE RESPONSIBLE FOR OUR FIRST WAVE OF
POTENTIALLY HEAVY PRECIP...WHICH IS CURRENTLY OVER WRN KY. THIS AREA
SHOULD EXPAND AND FILTER INTO OUR CWA THROUGHOUT THE MORNING. MAY
EVEN SEE A RUMBLE OF THUNDER OR TWO WITH THIS FIRST BATCH OF
RAINFALL GIVEN UPSTREAM TRENDS. WILL ONLY MENTION ISLD THREAT WEST
OF I-65 THIS MORNING. AFTER THIS MORNING`S MAIN AREA OF PRECIP...A
LULL IN THE PRECIP SHOULD OCCUR THIS AFTERNOON BEFORE ANOTHER LOW
PRESSURE WAVE RIDES NEWD ALONG THE FRONT TONIGHT...CAUSING ANOTHER
BOUT OF POTENTIALLY HEAVY RAIN.
THOUGH RAIN ONSET IS LATER THAN ANTICIPATED...STILL THINK THE FLOOD
WATCH IS WARRANTED THROUGH THE WEEKEND. PWATS ARE OVER AN INCH
NOW...AND NAM BUFKIT SOUNDINGS INDICATE NEAR 1.5 INCHES THIS
EVENING...WHICH IS SUPPORTED BY THE 4-5 STD DEVIATIONS ABV NORMAL
POSED BY THE SHORT-RANGE ENSEMBLES. ALSO...NAM AND GFS INDICATE SOME
ELEVATED INSTABILITY WITH LI`S AROUND ZERO TONIGHT...WHICH WILL AID
IN OVERALL PRECIP AMOUNTS GIVEN THIS CONVECTION. STILL THINK SOME
LOCATIONS COULD SEE 2-3 INCHES OF RAINFALL...WITH ISOLATED LOCATIONS
SEEING 4 INCHES OR MORE. HOWEVER...GIVEN THE SLOW ONSET THINK A
WIDESPREAD FLOODING EVENT IS NOT LIKELY...THOUGH A MINOR AND MORE
ISOLATED FLOODING EVENT IS CERTAINLY POSSIBLE...SO WILL CONTINUE
FLOOD WATCH. MAY DOWN PLAY AMOUNTS A WEE BIT BUT THAT IS ALL.
THE FRONT WILL BE CLOSELY ALIGNED WITH THE OHIO RIVER AROUND SUNRISE
AND SHOULD BE IN NEARLY THE SAME LOCATION OR JUST SE BY MIDNIGHT
TONIGHT. WILL KEEP CATEGORICAL POPS GOING...WITH MENTION OF LOCALLY
HEAVY RAINFALL.
FOR AVIATION CONCERNS...HAVE LOW-LEVEL WIND SHEAR IN ALL THE TAF
SITES THIS MORNING GIVEN THE STRONG SWRLY JET OF 40-45 KTS OVER THE
CWA NOW...EVIDENT FROM AREA VWPS AND SDF ACARS SOUNDINGS. MAY SEE
SOME GUSTY WINDS HERE AND THERE...BUT NOTHING OUT OF HAND AS CLOUDY
SKIES SHOULD HELP INHIBIT LARGER GUSTS.
TEMPS WILL BE TRICKY TODAY...AND COULD HAVE QUITE THE GRADIENT
ACROSS THE CWA...ESPECIALLY BY MIDDAY. TEMPS MAY DROP AND/OR STEADY
OUT ACROSS THE NW...WITH CURRENT READINGS IN THE UPPER 50S DROPPING
TO THE UPPER 40S AND HOLDING THERE. THE SERN CWA COULD SEE HIGHS A
FEW DEGREES WARMER THAN CURRENT READINGS...AND SHOULD STICK AROUND
60 FOR THE MOST PART. OVERNIGHT LOWS WILL NOT BUDGE MUCH AND SHOULD
BE JUST A FEW DEGREES COLDER THAN HIGHS TODAY.
AL
.LONG TERM (SUNDAY THROUGH FRIDAY)...
SUNDAY AND MONDAY...
FORECAST CHALLENGE WILL BE PLACEMENT OF THE COLD FRONT AT THE
BEGINNING OF THIS PERIOD. LATEST SHORT RANGE MODELS DID NOT
INITIALIZE SHALLOW COLD AIR WELL AND FEEL IT WILL BE FURTHER SOUTH
THAN MODELS SUGGEST. SURFACE WAVE SHOULD SHIFT THE COLD AIR NORTH
SOME DURING THE AFTERNOON SUNDAY AND AT THIS TIME WE WILL KEEP
PRECIPITATION ACROSS THE NORTH IN THE FORM OF RAIN. THE AXIS OF
HEAVY RAIN SUNDAY AND SUNDAY NIGHT STILL LOOKS TO BE ALONG THE OHIO
RIVER WHERE AN INCH TO AN INCH AND A HALF WILL BE POSSIBLE. LIGHTEST
AMOUNTS WILL OCCUR ACROSS THE SOUTHEAST PORTION OF THE COUNTY
FORECAST AREA. WE WILL HOLD ONTO ISOLATED THUNDERSTORMS SOUTH OF THE
OHIO RIVER SUNDAY WHERE BEST DYNAMICS EXIST...ALTHOUGH INSTABILITY
WILL BE LACKING.
TEMPERATURES WILL BE A CONCERN AS WELL AS A 10 TO 15 DEGREE GRADIENT
WILL BE NOTED ACROSS THE COLD FRONT. HIGHS SUNDAY WILL TOP OUT IN
THE LOWER 40S ACROSS SOUTHERN INDIANA WITH UPPER 50S EXPECTED NEAR
THE TENNESSEE BORDER.
ONCE THE SURFACE LOW MOVES NORTHEAST OF THE REGION THE MODIFIED
ARCTIC AIR WILL ENTER THE FORECAST AREA MONDAY. HIGHEST TEMPERATURES
WILL OCCUR DURING THE MORNING. LIGHT SNOW SHOWERS WILL BE POSSIBLE
MONDAY BUT NO ACCUMULATION IS EXPECTED.
JA
TUESDAY THROUGH FRIDAY...
NOT MUCH CHANGE IN THE FORECAST THROUGH THIS TIME PERIOD. WITH
FRONT CONTINUING TO OUR SOUTH AND HIGH PRESSURE BUILDING IN FROM THE
UPPER PLAINS...NORTHERLY WINDS WILL GET THE LAKE-EFFECT SNOW MACHINE
GOING TO OUR NORTH. DOWN THIS FAR SOUTH...FEEL THAT SCT FLURRIES
WILL BE POSSIBLE DURING THE DAY ON TUESDAY AND WILL LEAVE AS SUCH.
BETTER CHC FOR SNOW SHOWERS WOULD EXIST OVER FAR EAST KY IN THE
FAVORED UPSLOPE REGIONS. DRY FORECAST IS ANTICIPATED FOR WEDNESDAY
THROUGH FRIDAY AS HIGH PRESSURE CONTINUES TO BUILD OVER THE REGION.
TEMPERATURES AT THE BEGINNING OF THIS PD WILL BE WELL BELOW NORMAL
WITH HIGHS IN THE UPPER 20S TO LOWER 30S AND OVERNIGHT LOWS IN THE
UPPER TEENS. SOME MODERATION IN THE TEMPERATURES WILL OCCUR BY
THURSDAY AND FRIDAY WITH TEMPERATURES WARMING SLIGHTLY INTO THE
MID AND UPPER 30S. GENERALLY STUCK CLOSE TO THE HPC GUIDANCE
THROUGH THIS PERIOD.
MJ
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...FLOOD WATCH THROUGH LATE SUNDAY NIGHT FOR KYZ023>043-045>049-
053>057-061>067-070>078-081-082.
IN...FLOOD WATCH THROUGH LATE SUNDAY NIGHT FOR INZ076>079-083-084-
089>092.
&&
$$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
AFDMQT 410 PM EST SAT JAN 13 2007
.SYNOPSIS...
WV IMAGERY INDICATED CONFLUENT MID/UPPER LEVEL FLOW FROM THE NRN
PLAINS TO THE WRN GREAT LAKES WITH A SRN BRANCH TROF OVER THE SW
CONUS AND BROAD CYCLONIC NRN STREAM FLOW THROUGH SRN CANADA. AN
UPSTREAM SHRTWV WAS SLIDING SE FROM CNTRL/NRN MANITOBA INTO NW
ONTARIO. MID/HIGH CLOUDS WERE ALSO STREAMING INTO THE REGION WITH SW
FLOW FROM THE SRN/CNTRL PLAINS. AT THE SFC...A RDG EXTENDED FROM
QUEBEC THROUGH UPPER MI TO THE CNTRL PLAINS. AN UPSTREAM ARCTIC COLD
FRONT EXTENDED FROM NW ONTARIO TO SRN SASK. LEFTOVER FLURRIES OVER
CNTRL AND E UPPER MI WERE QUICKLY DIMINISHING AND MOVING OFFSHORE
AS WINDS BACK SWRLY. WITH VERY DRY 900-700 LAYER...PER 19Z TAMDAR
SNDGS...NO LIGHT SNOW OR FLURRIES WERE OBSERVED OVER NRN WI DESPITE
10DBZ-20DBZ RADAR RETURNS OVER THE AREA. SHORTWAVE OVR SOUTHWEST
WILL BE OF INTEREST LATE SUN INTO MON.
&&
.SHORT TERM (TONIGHT AND SUNDAY)
MAIN FCST CONCERNS ARE LES TRENDS.
TONIGHT...EXPECT ENHANCED LOW LVL CONV AND QUICKLY VEERING WINDS AS
THE FRONT MOVES THROUGH LK SUPERIOR AND UPPER MI BTWN 06Z-12Z.
MOISTURE WITH THIS NRN STREAM SYSTEM IS VERY LIMITED WITH BEST
QVECTOR CONV WELL TO THE NORTH...AND MOISTURE INFLOW FROM SW STREAM
SHOULD REMAIN MAINLY S OF LK SUPERIOR. SO CONDITIONS WILL BE
MARGINAL FOR MORE THEN LIGHT LES. HOWEVER...EXPECCT COVERAGE TO
INCREASE LATE TONIGHT WITH THE FRONT MOVING INTO THE KEWEENAW AFT
MIDNIGHT AND TOWARD THE NE CWA...MAINLY E OF KP53 AFT 12Z. INVERSION
HEIGHTS ARE FCST TO REMAIN IN THE 3K-4K FT RANGE (TEMP NEAR -15C AT
THE TOP OF THE INVERSION) WITH ONLY LIMITED CONVECTION DEPTH AND
CHANGING WIND DIRECTION...SO ONLY AN INCH OR TWO IS EXPECTED.
MID LEVEL CLOUDS THIS EVENING AND LAKE CLOUDS LATER TONIGHT WILL
KEEP TEMPS FROM DROPPING OFF QUITE AS MUCH AS PREVIOUS FCST FOR
INLAND LOCATIONS.
SUN...AS WINDS VEER MORE NRLY WITH RIDGING INTO NRN ONTARIO BEHIND
THE FRONT...LIGHT SNOW SHOWERS WILL SPREAD INTO THE REST OF NORTHERN
UPPER MI. AGAIN...WITH ACYC SYNOPTIC FLOW AND 3K FT INVERSION...ONLY
LIGHT ACCUMULATIONS EXPECTED...GENERALLY AN INCH OR LESS.
&&
.LONG TERM (SUN NIGHT THROUGH NEXT SAT)...
MAIN CONCERN IN THIS PERIOD IS SNOW AMOUNTS SUN NIGHT THROUGH MON
NIGHT.
SHORTWAVE TROUGH FOR SUN NIGHT INTO MON NOW LOOKS LIKE IT WILL LIFT
A BIT FARTHER NORTH THAN EARLIER THOUGHT. PRIMARY SFC LOW STILL
REMAINS WELL TO THE SOUTH OF UPR MI...TRACKING ACROSS THE NORTHERN
OHIO VALLEY. APPEARS THERE WILL BE TWO AREAS OF PCPN. ONE AREA WILL
BE ALONG SFC FRONT OVER OHIO VALLEY...WHILE ANOTHER PCPN AREA OF
MOSTLY FREEZING RAIN AND SNOW WILL SPREAD ENE ALONG THE MID LEVEL
CIRCULATION. ALL GUIDANCE EXCEPT GFS INDICATES AT LEAST SOUTHERN
TIER OF CWA WILL BE IMPACTED BY NORTHERN FRINGE OF SNOW FM WI INTO
NORTHERN LWR MI. GFS SHARPLY DIFFERENT WITH MORE SHEARED OUT UPR
LEVEL WAVE AND NOT AS FAR NORTH OF A PUSH WITH PCPN. FOR NOW...TRIED
TO USE A BLEND OF GFS/NAM IDEAS FOR FORECAST. THIS BLENDED IDEA
RESULTS IN INCREASE IN POPS IN FAR SCNTRL CWA LATE SUN NIGHT INTO
MON WITH SYNOPTIC SNOW. COULD SEE A COUPLE INCHES FM MENOMINEE TO
ESCANABA.
CLOSER TO LK SUPERIOR WILL ALREADY HAVE SUFFICIENT INSTABILITY FOR
LK EFFECT SNOW IN MOSTLY NNW FLOW BY SUN EVENING. LIKELY POPS LOOK
FINE. EXPECT TO SEE SOME INCREASE IN LK EFFECT LATER SUN NIGHT INTO
MON AS INVERSION RISES TO AROUND 5KFT AS H85 TEMPS FALL TO -18C OR
SO AND PARTIAL DEEP MOISTURE ADVECTS IN FM SOUTH. LOCAL LK EFFECT
GUIDANCE SUGGESTS AMOUNTS MEETING ADVY CRITERIA WOULD BE LIKELY
SUN NIGHT INTO MON OVER FAR WEST AND NCNTRL CWA WHERE LWR LEVEL WIND
DIRECTION OF 350-020 IS FAVORABLE. ONE STUMBLING BLOCK THOUGH...AND
A BIG ONE AT THAT...IS THAT IF A SOLN MORE IN LINE WITH NAM IS
REALIZED POTENTIAL EXISTS FOR MUCH MORE FAVORABLE SETUP FOR HEAVY LK
EFFECT SNOW. KEY IS NAM SHOWING MUCH MORE DEEPER MOISTURE AND AN
INVERSION HEIGHT TOWARD H7...WITH THE SAME H85 TEMPS AS GFS AND FOR
MOST PART SAME WIND DIRECTION. NAM ALSO INDICATES MUCH MORE
CYCLONIC/CONVERGENT LOWER LEVEL FLOW. BASICALLY...IF NAM SOLN
VERIFIES ADVY LOOKS FAIRLY CERTAIN AND SOME LOCALIZED WARNING
AMOUNTS WOULD BE POSSIBLE.
KIND OF STUCK AT THIS POINT. HARD TO TELL WHICH SOLUTION OR SOLUTION
MORE SIMILAR TO IT...WILL VERIFY. USUALLY...TRY TO GO WITH MAJORITY
IDEA...BUT WITH GFS SO DIFFERENT AND SOME SUPPORT TO ITS SOLUTION FM
ENSEMBLES...TRIED TO GO WITH COMPROMISE SOLUTION FOR SNOW COVERAGE
AND AMOUNTS. SINCE CONFIDENCE IS LOW...WILL NOT ISSUE ANY HEADLINES
RIGHT NOW EITHER. WILL MENTION THE EVENT IN THE HWO.
LOWER LEVEL FLOW BACKS TO NW ON TUE SO KEPT LK EFFECT OVER NW UPR MI
AND FOR AREAS EAST OF MARQUETTE. INVERSION GRADUALLY LOWERS BY TUE
NIGHT...SO LK EFFECT INTENSITY SHOULD BE DIMINISHING.
UPR FLOW BRIEFLY BECOMES ZONAL WED WITH LOW PRES PASSING ACROSS
NORTHERN MANITOBA AND ONTARIO. WINDS BECOME SW IN LOWER LEVELS WHICH
WILL KEEP SNOW SHOWERS ONLY OVER FAR NORTHERN KEWEENAW PENINSULA.
SFC TROUGH THEN FOLLOWS INTO UPR LAKES ON THU. UPR TROUGH LIFTING FM
PLAINS MAY COMBINE WITH THE SFC BOUNDARY TO BRING A LITTLE LIGHT
SNOW THU. MARGINAL DEEPER MOISTURE SO NOTHING MORE THAN LOW CHANCE
POPS ATTM. COLDER AIR SPILLS IN FOR FRI SO INCREASED LK EFFECT NEAR
LK SUPERIOR IN NW/N FLOW AREAS. LOOSE AGREEMENT ON CLIPPER TYPE
SYSTEM FOR SOMETIME NEXT WEEKEND. 00Z/06Z GFS BY FAR THE MOST
AGGRESSIVE BUT ECMWF/UKMET/CANADIAN WERE MORE IN LINE WITH PREFERRED
LATEST HPC GUIDANCE.
COORD WITH GRB AND DLH...THANKS.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
AFDMKX 817 PM CST SUN JAN 14 2007
.DISCUSSION...FOCUS ON WINTER STORM HITTING AREA TONIGHT.
NEW 00Z UPPER AIR DATA INDICATING A SYSTEM SLIGHTLY DEEPER THAN
PREVIOUS RUNS HAD FOR THIS TIME. HOWEVER...TEMP AND MOISTURE
PLACEMENT WITHIN VERY TIGHT BAROCLINIC ZONE FCST SURPRISINGLY
ACCURATELY BY THE EARLIER 18Z RUNS...COMPARED TO NEW UA DATA. WE
HAVE HAD A SOMEWHAT UNEXPECTED PUSH OF FREEZING RAIN INTO
SOUTHEAST WISCONSIN THIS EVENING. ACARS AIRCRAFT SOUNDINGS DO SHOW
A WARM LAYER BETWEEN H8 AND H7...BUT JUST BARELY ABOVE 0C. IT
APPEARS THIS MOISTURE PUSH IS PRIMARILY IN THE LOW LEVELS WITH A
THE FAVORED ICE CRYSTAL GROWTH REGION STILL RATHER DRY. THAT I
BELIEVE IS KEY TO THE LIQUID VS FROZEN NATURE OF THIS EARLY ONSET
PRECIP. THIS IS CHANGING RAPIDLY AS MORE COLUMN MOISTURE ARRIVES
FROM THE SOUTHWEST. THINGS ARE AND WILL CONTINUE TO CHANGE OVER
QUICKLY TO ALL SNOW FROM WEST TO EAST.
NEW NAM AND NGM ARE COMING IN AND SHOW A LITTLE LESS IN THE WAY OF
TOTAL QPF. STILL LOOKS LIKE A 3 TO 5 INCH SNOW ACCUMULATION BUT
GIVEN THE MIXED NATURE OF IT ANTICIPATED LATER ON AND THE
INCREASING WINDS FROM THE NORTH...THE WARNING IS STILL JUSTIFIED.
IT IS POSSIBLE THIS MAY END UP BEING JUST A GOOD WINTER WEATHER
ADVISORY EVENT...BUT AT THIS POINT...ENOUGH UNCERTAINTY TO KEEP
THINGS AS IS.
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 6 PM CST MONDAY FOR WIZ046-WIZ047-
WIZ051-WIZ052-WIZ056-WIZ057-WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-
WIZ064-WIZ065-WIZ066-WIZ067-WIZ068-WIZ069-WIZ070-WIZ071-WIZ072.
&&
$$
DAVIS