Forecast Discussions mentioning "ACARS", "MDCRS", "AIRCRAFT", "TAMDAR", or "AMDAR" received at FSL on 02/24/07

AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
900 AM PST THU FEB 22 2007 .SYNOPSIS... A WINTER STORM WILL BRING MODERATE RAIN...HEAVY MOUNTAIN SNOW...AND GUSTY WINDS LATE THIS AFTERNOON THROUGH FRIDAY. SHOWERS WILL END BY FRIDAY EVENING. HIGH PRESSURE WILL MOVE ACROSS THE AREA SATURDAY BRINING FAIR SKIES AND WARMER TEMPERATURES. INCREASING CLOUDS ON SUNDAY AND A COOLING TREND ON MONDAY AS A COLD FRONT MOVES SLOWLY SOUTH THROUGH CALIFORNIA. RAIN AND MOUNTAIN SNOW ARE POSSIBLE NEXT TUESDAY AND WEDNESDAY AS THE FRONT MOVES ACROSS SOUTHERN CALIFORNIA. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM (TODAY THROUGH SUNDAY)... FORECAST LOOKS ON TRACK BASED ON OBSERVATIONS AND SPEED OF MOVEMENT OF TROUGH. NO MAJOR CHANGES ANTICIPATED TO FORECAST IN SHORT TERM. DEEP MARINE LAYER THIS MORNING...AT LEAST 5000 FEET PER KNKX SOUNDING AND STRATUS SPILLING INTO HIGH DESERT...WITH AREAS OF LIGHT RAIN/DRIZZLE FROM NORTH SAN DIEGO COUNTY TO THE SOUTH SLOPES OF THE SAN BERNARDINO MOUNTAINS. THE MODERATE TO HEAVY RAIN ASSOCIATED WITH THE FRONT WILL ARRIVE LATE AFTERNOON AND DURING THE THE EVENING. EXTRAPOLATION OF STRONG RADAR ECHOES OFF POINT CONCEPTION HAS LEADING EDGE REACHING SEAL BEACH AROUND 1630 PST...WRIGHTWOOD-ONTARIO-SAN CLEMENTE AROUND 1730 PST... HESPERIA-RIVERSIDE-LAKE ELSINORE-OCEANSIDE AROUND 1830 PST. THIS SHOULD RESULT IN A MAJOR IMPACT ON AFTERNOON/EVENING COMMUTE ACROSS LA BASIN/ORANGE COUNTY/INLAND EMPIRE/CAJON PASS. THE REMAINDER OF THE MOUNTAINS...INLAND VALLEYS AND SOUTH SAN DIEGO COUNTY NOT EXPECTED TO RECEIVE HEAVY PRECIPITATION UNTIL AFTER 1900 PST. THE FRONT SHOULD PUSH EAST OF THE SAN DIEGO COUNTY MOUNTAINS AROUND 0100 PST FRIDAY. THE SNOW LEVEL THIS EVENING WILL LOWER FROM 5000 FEET TO AROUND 3500 FEET MOST AREAS BY FRIDAY MORNING AND CLOSER TO 2500 FEET OVER HIGH DESERT. MODELS HAVE BEEN CONSISTENT IN GENERATING A SECOND ROUND OF PRECIPITATION EARLY FRIDAY MORNING. THIS IS THE MOST LIKELY PERIOD THAT THE LOWER SLOPES/FOOTHILLS/HIGH DESERT FLOORS WILL SEE SNOWFALL. THE UPPER TROUGH AXIS IS EXPECTED TO BE EAST OF SAN DIEGO COUNTY BY 0700 PST FRIDAY...BUT INSTABILITY/UPSLOPE FLOW AND ISLAND EFFECT EXPECTED TO CONTINUE TO GENERATE SHOWERS INTO FRIDAY EVENING. CURRENT WARNINGS/ADVISORIES AND QPF AMOUNTS LOOK GOOD AND ONLY PLAN TO RUBBER STAMP THEM ON THE 1000 PST UPDATE. AM STILL CONSIDERING A SNOW/BLOWING SNOW ADVISORY TONIGHT FOR THE APPLE/LUCERNE VALLEY. NEED TO COORDINATE WITH ADJACENT OFFICES FIRST. HIGH PRESSURE RIDGE BUILDING TONIGHT AND SATURDAY. DRYING AND WARMING TREND EXPECTED TO BE SHORT LIVED AS RIDGE AXIS IS ALREADY MOVING EAST BY SATURDAY AFTERNOON AND NEAR ZONAL FLOW BECOMES ESTABLISHED LATE SUNDAY/MONDAY. && .LONG TERM (MONDAY THROUGH WEDNESDAY)... A BROAD TROUGH WILL BE OVER NORTH AMERICA WITH STRONG ZONAL FLOW BETWEEN 30-40N LATITUDE FROM 140W LONGITUDE TO THE ATLANTIC COAST. CONFIDENCE IN MODEL TIMING ON EMBEDDED SHORT WAVES IS VERY LOW AND FULLY EXPECT TO SEE MAJOR CHANGES FROM RUN TO RUN. BEST FORECAST FOR NOW IS CLOUDY AND COOL WITH CHANCE OF PRECIPITATION. && .AVIATION... EARLY MORNING ACARS SOUNDINGS INDICATE THE MARINE LAYER DEPTH RANGED FROM NEAR 4000 FEET OVER KSAN TO 6000 FEET NEAR KONT. MULTIPLE LAYERS OF STRATOCU COVER THE AREA AND SHOULD CONTINUE THROUGH THE DAY. THE LOWEST SCATTERED LAYER WAS AROUND 1500 FEET MSL WITH ADDITIONAL BROKEN LAYERS AT 3000 FEET AND 5000 FEET MSL. LAYERS OF STRATOCU SHOULD CONTINUE THROUGH THE DAY. A COLD FRONT APPROACHING FROM THE WEST AT 25 KTS SHOULD REACH THE KSNA AREA BY 00Z AND KSAN BY 02Z WITH THE BACK EDGE MOVING THROUGH 3 TO 4 HOURS LATER. BASED ON METAR REPORTS VICINITY OF THE COLD FRONT ALONG THE CENTRAL COAST...BASES SHOULD REMAIN IN THE MVFR CATEGORY DURING FRONTAL PASSAGE ALTHOUGH SOME IFR CONDITIONS ARE POSSIBLE IN HEAVIER SHOWERS. CONTINUED MVFR CONDITIONS BEHIND THE FRONT WITH BROKEN CU/TCU BASES AROUND 1500 TO 2000 MSL AND LOCAL VISIBILITY RESTRICTIONS IN SHOWERS. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...WIND ADVISORY FROM 4 PM THIS AFTERNOON TO 6 PM PST FRIDAY FOR COACHELLA VALLEY-SAN DIEGO COUNTY DESERTS. WINTER STORM WARNING FROM 6 PM THIS EVENING TO 12 PM PST FRIDAY FOR RIVERSIDE COUNTY MOUNTAINS-SAN BERNARDINO COUNTY MOUNTAINS-SAN DIEGO COUNTY MOUNTAINS. WIND ADVISORY FROM NOON TODAY TO 10 PM PST FRIDAY FOR APPLE AND LUCERNE VALLEYS. SNOW AND BLOWING SNOW ADVISORY FROM 6 PM THIS EVENING TO 12 PM PST FRIDAY FOR SANTA ANA MOUNTAINS AND FOOTHILLS. PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 6 PM THIS EVENING TO 10 PM PST FRIDAY FOR COASTAL WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER AND OUT 30 NM-WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND. && $$ PUBLIC...MARTIN AVIATION/MARINE...WHITLOW NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
600 PM CST FRI FEB 23 2007 .UPDATE... 600 PM CST SENT QUICK UPDATE TO THE ZONES AND GRIDS. REFER TO THE AVIATION DISCUSSION BELOW FOR DETAILS. && .DISCUSSION...AFTERNOON FORECAST... 230 PM CST INITIAL ROUND OF MID LEVEL WARM ADVECTION SENDING A PLUME OF CLOUDS ACROSS FCST ARE THIS AFTERNOON. ASIDE FROM PUTTING A LID ON TEMPERATURE RISE LOW LEVEL DRYNESS HAS PRECLUDED ANY SFC PRECIP. UPPER TROUGH AND SURFACE FRONT MOVING INTO WRN COLO THIS AFTERNOON AND WARM INCRESINGLY MOIST AIRMASS ADVECTING N INTO CENTRAL PLAINS. SFC LO EXPECTED TO FORM OVER THE WESTERN HIGH PLAINS OF COLO-KANSAS TONIGHT AND TRACK NE TOWARD MID MISS VALLEY SAT INTO EARLY SUNDAY. MODELS SUGGEST THIS SYSTEM WILL RAPIDLY OCCLUDE AND ACTURALLY BEGIN DECAY/FILLING PROCESS AS IT REACHS LOWER WESTERN LAKES SUNDAY. LOW LEVELS AS SAMPLED BY TAMDAR FLIGHTS IN CENTRAL IL ARE VERY DRY AND SE WINDS CONTINUE TO ADVECT TEENS DEW PTS INTO REGION THIS AFTERNOON. NEW GFS HAS COME INTO PHASE WITH NAM AND OTHER MODELS IN SLOWING ONSET OF APPROAHING LOW AND PRECI UNTIL LATER SAT. THE UPSHOT OF ALL THIS IS AN EXPECTED BEGINNING OF PRECIP SAT AFTN OVER NWRN IL SPREADING INTO NW IN AFTER SUNSET. LOW DEW POINT AIR AND DRY LOWER LEVELS INDICATE AN INITIAL LOW WET BULB /BELOW FREEZING/ CONDITION TO BEGIN ANY PRECIP AS SNOW. WIND FIELD AROUND APPROACHING LOW WILL INCR RAPIDLY LATER SAT AND SAT NIGHT WITH VERY WELL DEVELOPED WARM ADVECTION SIGNAL SEEN IN MODEL SOUNDINGS AFTER 00Z SUN /6PM SAT/. THIS SIGNAL IS IN VICINITY OF THE TROWAL FEATURE OF THE OCCLUSION AND PRONE TO THE MOST INTENSE PRECIP. MODEL SOUNDINGS ALSO REVEAL THE TEMPERATURE PROFILE TO HOVER AROUND 0 DEG C BELOW 850MB OVER AT LEAST THE NRN HALF OF THE FCST AREA INTO SUNDAY MORNING WHICH SUPPORTS A MIXED PRECIP WITH THE POTENTIAL FOR SIGNIFICANT FRZG RAIN OR SLEET. SNOW MAY DOMINATE TOWARD THE WISC BORDER WITH GRID TOTAL OF 5-7 INCH STORM TOTAL REFLECTING THE INITIAL GUESS. ELSEWHERE ACCUMULATIONS OF SLEET AND SOME FREEZING RAIN WILL REDUCE TOTALS. RAIN WILL LIKELY DOMINATE SOUTH OF THE KANKAKEE RIVER TOWARD PONTIAC. MOST CONCENTRATED PRECIP PERIOD APPEARS TO BE BETWEEN 6PM SAT AND 6AM SUN WITH RESIDUAL SNOW CONTINUING SUNDAY. AS UPPER TROUGH WEAKENS OVERHEAD AND SLOWLY RECEDES TO THE EAST PERIODS OF LIGHT SNOW ARE EXPECTED TO PERSIST INTO MON AND TUE. ANOTHER HIGH AMPLITUDE UPPER TROUGH MOVING ONTO THE WEST COAST AT MIDWEEK WILL KICK OFF ANOTHER PLAINS CYCLONE ABOUT THURS WITH A MODEST WARM UP TOWARD THE END OF THE WEEK. TEMPS TONIGHT WILL BE MODIFIED BY CLOUDS ALTHOUGH IF CLOUDS THIN LATER IN THE NIGHT DRY AIR MAY ALLOW BRIEF DIP..BUT WILL GO ABOVE GUIDANCE PLAYING FOR CLOUDS. THIS SYSTEM HAS THE POTENTIAL TO BE A SIGNIFICANT PRECIPITATION PRODUCER GIVEN THE SLOWING NATURE OF MOVEMENT AS IT APPROACHES. PRECIP TYPE UNCERTAINTY IS A CONCERN ALTHOUGH THAT MAY BE OFFSET SOME BY THE SE TRAJECTORY OF THE INCOMING AIRMASS..AS OPPOSED TO A NE COMPONENT. SNOW TOTALS GOING NORTH TOWARD THE WISC BORDER WILL INCREASE RAPIDLY ESPECIALLY NORTH OF THE BORDER. WHILE THE OVERALL SCENARIO HAS BECOME MORE CLEAR THE DETAILS OF PRECIP TYPE IS A LINGERING CONCERN KML && .AVIATION... 600 PM CST 00Z TAFS...LARGE BATCH OF MIXED PRECIP OVR ERN IA WAS MOVING INTO NWRN IL AS OF 00Z. KDKB REPORTED A BRIEF PERIOD OF 4SM -SN AROUND 23Z ON THE LEADING EDGE OF THIS BAND. THE LOW-LEVEL WARM ADVECTION AND MID-LEVEL SHORTWAVE RESPONSIBLE FOR THIS PRECIP ARE EXPECTED TO CLIP EXTREME NRN IL THIS EVENING. RADAR ECHOES 35-45DBZ AND SFC REPORTS JUST WEST OF THE MISSISSIPPI RIVER INDICATE POCKETS OF MDT/HVY SLEET. THIS ACTIVITY SHOULD WEAKEN AND BECOME MORE SCATTERED AS IT MOVES EAST ACROSS THE LOCAL AREA...BUT SHOULD STILL BRING A PERIOD OR TWO OF -SN AND SLEET TO RFD AND ORD. FURTHER SOUTH AT MDW...DPA... AND GYY FORCING IS RATHER LIMITED AND UPSTREAM ECHOES TO THE WSW ARE LACKING. THUS WILL MAINTAIN DRY FCST THERE. WINDS HOLDING A BIT MORE NORTHEAST THAN MODEL GUIDANCE SUGGESTED...LIKELY IN RESPONSE TO A SLIGHTLY STRONGER HIGH TO OUR NE. RESULTANT LONGER FETCH OF WINDS ACROSS LAKE MICHIGAN WILL KEEP MVFR CIGS INVOF ORD THROUGH EVENING...WITH EVENTUAL SCATTERING OUT BY 06Z. WINDS INCREASE SHARPLY TOMORROW OUT OF THE EAST AS LOW PRESSURE RAPIDLY DEEPENS OVR KS AND SFC HIGH REMAINS OVR ONTARIO. WARM AND VERY MOIST AIR ADVECTING NWD OVR THE COOL AND DRIER SFC LAYER LATE SAT AFTN MAY ALLOW SOME -FZDZ TO DEVELOP AFT 22Z SAT. HIGHER PROBABILITY/COVERAGE PRECIP SHOULD HOLD OFF TIL CLOSER TO 00Z SUN. HANDEL && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...WINTER STORM WATCH 18Z SATURDAY TO 00Z MONDAY WINNEBAGO BOONE MCHENRY LAKE COOK DUPAGE KANE DEKALB OGLE LEE LASALLE KENDALL GRUNDY WILL. .IN...WINTER STORM WATCH 18Z SATURDAY TO 00Z MONDAY LAKE PORTER. .LM...GALE WRNG ALL LM AND NR SHORES 21Z SAT TO 21Z SUN.. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1013 PM EST FRI FEB 23 2007 .UPDATE... MAIN FCST ISSUE OVERNIGHT IS POTENTIAL OF -SN OVER FAR WRN UPPER MI AROUND KIWD. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A SHARP TROF MOVING THRU THE ROCKIES WITH VORT MAX OVER THE 4CORNERS. DOWNSTREAM...PRONOUNCED MIDLEVEL RIDGE WAS OVER THE MISSISSIPPI VALLEY. AHEAD OF THE TROF...STRONG SRLY FLOW HAS DEVELOPED ALL THE WAY FROM TX TO DAKOTAS/MN PER 00Z RAOBS/PROFILERS WHICH SHOW 40-50KT AT 850MB. THE STRONG SRLY FLOW/WAA IS LEADING TO HEALTHY ISENTROPIC ASCENT ACROSS THE UPPER MISSISSIPPI VALLEY. PER 00Z RUC...STRONGEST ASCENT IS OVER ERN IA/SE MN WHERE PERSISTENT TSRA HAVE BEEN OCCURRING DURING THE LAST FEW HRS. SOMEWHAT WEAKER ASCENT IS SUPPORTING BAND OF SNOW ACROSS NE MN INTO WRN WI. SNOW IS HAVING A TOUGH TIME MOVING E FOR 2 REASONS. FIRST...THE ISENTROPIC ASCENT IS NOT REALLY SHIFTING E MUCH IF AT ALL...AND SECOND...THERE IS A CONTINUAL FEED OF DRY AIR FROM THE E AS NOTED BY EVENING TAMDAR SOUNDINGS FROM KSAW (DWPT DEPRESSIONS BLO 700MB ARE GENERALLY IN THE 15-20C RANGE). MAIN AREA OF SIGNIFICANT PCPN OVERNIGHT SHOULD SET UP ACROSS CNTRL/SRN WI AS STRONGER/FOCUSED ISENTROPIC ASCENT AND MDT/STRONG LOW TO MIDLEVEL FRONTOGENESIS WILL SET UP THERE. THIS SHOULD INTERCEPT SOME OF THE MOISTURE ADVECTION FARTHER N...AND WHEN COMBINED WITH A CONTINUAL FEED OF DRY AIR FROM THE E...IT WILL BE TOUGH FOR -SN TO SPREAD INTO WRN UPPER MI OVERNIGHT. WILL THUS HOLD EWD PROGRESSION OF -SN TO JUST W OF KIWD THRU THE NIGHT. AS FOR TEMPS...CLOUDS ARE THINNEST OVER THE E...SO IT`S NO SURPRISE TO SEE THE LOWEST TEMPS THERE RIGHT NOW (KERY WAS 9F AT 03Z). GOING FCST SEEMS ON TRACK WITH MINS DOWN AROUND 0F IN THAT AREA. WILL BRING MINS UP A FEW DEGREES OVER THE CNTRL FCST AREA AS THICKER CLOUD COVER AND STIRRING WINDS HAVE NOT ALLOWED TEMPS TO DROP MUCH THIS EVENING. MINS IN THE 10-15F DEGREE RANGE SHOULD BE THE RULE. EXPECT HIGHEST READINGS OVER THE W (15-20F) AS CLOUDS WILL BE THICKER AND WINDS A BIT STRONGER. && .PREV DISCUSSION (ISSUED AT 340 PM EST)... SYNOPSIS... THE CWA CURRENTLY RESIDED BETWEEN HIGH PRESSURE JUST TO OUR NORTHEAST...AND THE ORGANIZING STORM SYSTEM TO OUR SOUTHWEST. THANKS TO THE SURFACE HIGH...EAST TO NORTHEASTERLY FLOW HAS BEEN ABLE TO SLOWLY SCOUR OUT MUCH OF THE LAKE EFFECT SNOW SHOWERS AND FLURRIES THAT WERE PREVALENT ACROSS THE CENTRAL LAKE SUPERIOR SHORELINE LATE THIS MORNING. THIS SURFACE HIGH WILL CONTINUE TO SLOWLY LOSE ITS INFLUENCE ON THE UPPER PENINSULA...AS HIGH CLOUDS INVADE FROM THE SOUTHWEST. SHORT TERM (TONIGHT AND SATURDAY)... THE UPPER PENINSULA WILL CONTINUE TO BE IN BETWEEN SYSTEMS THROUGH THIS PERIOD. DRY LOWER LEVELS OF THE ATMOSPHERE ARE STILL ANTICIPATED TO SLOW DOWN THE ONSET OF SNOW SATURDAY. THIS SHOULD RESULT IN THE NORTHEASTERN TWO-THIRDS OF THE CWA REMAINING DRY THROUGH 00Z SUNDAY. HIGH CLOUDS WILL CONTINUE TO SLOWLY INVADE...THICKEN AND LOWER OVER THE NEXT 12-18 HOURS...WITH A BKN TO OVC SKY FOR ALL BY 15Z SATURDAY. SMALL CHANGES WERE MADE TO THE INHERITED FORECAST FOR THIS PERIOD. THE FIRST WAS TO SLOW DOWN THE APPROACHING THICKER CLOUDS...AS THEY SEEM TO BE HAVING A HARD TIME ACROSS THE CENTRAL UPPER PENINSULA...AND NORTHEASTERN WISCONSIN. THE BEST CLOUDS ARE LOCATED TO OUR WEST...OVER NORTHERN AND CENTRAL MINNESOTA...RIDING ATOP THE 500MB RIDGE OVER THIS AREA. WITH FEWER CLOUDS THAN ORIGINALLY ANTICIPATED...HAVE GONE AHEAD AND LOWERED THE OVERNIGHT LOWS EVER SO SLIGHTLY ACROSS THE CENTRAL AND EASTERN PORTIONS OF THE CWA. LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... ON SAT NGT...12Z GFS/UKMET/NAM SHOW OCCLUDED LO MOVING TO NRN MO BY 12Z SUN. DRY ELY FLOW ON THE SRN FLANK OF HUDSON BAY HI PRES IS FCST TO REMAIN DOMINANT AND KEEP DEEPER MSTR AT BAY TO THE SW. WL MAINTAIN LO CHC POPS OVER WRN LK SUP AND NR THE WI BORDER...OTRW EXPECT DRY CONDITIONS WITH ONLY THIN HI CLD OVER THE E CLOSER TO H5 RDG AXIS. EXPECT THE LOWEST MIN TEMPS OVER THE INTERIOR E CLOSER TO CORE OF DRIER AIR (PWAT ARND 0.10 INCH). AS OCCLUSION DRIFTS INTO NCNTRL IL BY 00Z MON...GFS/UKMET/CNDN SHOW DEEPER MSTR MAKING SLOW PROGRESS TO THE NE IN THE FACE OF DRY LLVL ESE FLOW. NAM IS A BIT FARTHER N WITH THE FCST OCCLUDED LO...BUT PREFER THE FARTHER S SCENARIO OF THE GFS/UKMET BASED ON RECENT TRENDS TOWARD A SLOWER...MORE SRN TRACK. GFS SHOWS ISENTROPIC ASCENT ON THE 280-290K SFCS AS WELL AS DEEPER SATURATION NR THE WI BORDER DURING THE DAY...SO WL MAINTAIN HIER POPS IN THAT AREA. SINCE ANTECEDENT DRY AIRMASS WOULD FAVOR A SHARP NRN GRADIENT ON THE SN... CUT POPS A BIT FARTHER TO THE N IN AREAS WHERE THE LIFT ON THE 280K SFC IS FCST TO BE WEAKER OR NEUTRAL AND LLVL DRY AIR EXPECTED TO BE MORE TENACIOUS. NEW NCEP GRAPHICS HINT AT 4-6" OF SN FOR THE SAT NGT-SUN PD ACRS THE S HALF OF MNM COUNTY...SO EXPECT LATER SHIFTS WL HAVE TO ISSUE AN ADVY FOR THIS AREA (AND MAYBE IRON/DICKINSON/DELTA COUNTIES AS WELL) WHERE ELY FLOW OFF NRN LK MI MIGHT ADD SOME MOISTURE/LK ENHANCEMENT. GFS FCST SDNGS SHOW 30-35KT WINDS WITHIN MIXED LYR AT MNM BLO WAD INVRN AT H9...SO ADDED AREAS OF BLSN AS WELL IN THAT AREA. ON SUN NGT...GFS/CNDN MODELS SHOW DRIER AIR PUSHING BACK TO THE S WITH BACKING LLVL FLOW AS SFC LO DRIFTS TO NR SW LWR MI BY 12Z MON. UKMET HINTS DEEPER MSTR WL CONTINUE TO RIDE TO THE N WITH OCCLUSION ENDING UP NR CHI BY 12Z MON. QUICK LOOK AT NEW 12Z ECMWF SHOWS A SIMILAR SOLN TO THE GFS/CNDN MODELS...AND NCEP MANUAL GRAPHICS SHOW LESS SN FALLING DAY3 IN LINE WITH THIS FCST/RECENT MODEL TRENDS WITH STUBBORN HUDSON BAY HI. SO WL TEND TOWARD THE GFS FCST SCENARIO FOR GRID/FCST EVALUATION. HUDSON BAY HI PRES FCST TO BLD INTO THE UPR GRT LKS ON MON/TUE... FORCING LO PRES IN THE LOWER GRT LKS TO SLIDE TO THE E. HAVE GENERALLY LOWERED POPS FM EARLIER FCSTS PER NCEP GUIDANCE AND INFUSION OF DRIER AIR FM THE N. BEST CHC OF LINGERING POPS OVER THE SE AND HIER TERRAIN OF THE NCNTRL WITH UPSLOPE NE WIND. TUE NGT LOOKS TO BE QUITE COLD WITH SFC RDG AXIS/LGT WINDS/DRY AIR OVHD. TENDED TOWARD THE LO END OF MOS GUIDANCE FOR WED LO TEMPS. WAD BTWN DEEPENING UPR TROF OVER THE ROCKIES/DVLPG LO PRES IN THE WRN PLAINS AND HUDSON BAY HI PRES FCST TO IMPACT THE UPR GRT LKS ON WED. EXPECT INCRSG CLDS BUT ANY PCPN TO REMAIN TO THE W WITH ABUNDANT DRY AIR IN THE LO/MID TROP TO BE OVERCOME. SOME DISCREPANCY AS FAR AS EVOLUTION OF TROF/ SFC LO LIFTING OUT OF THE W NEXT THU/FRI. 00Z ECMWF AND RECENT OPERATIONAL GFS MODELS TEND TO LIFT SHRTWV/SFC LO FARTHER W WHILE MAJORITY OF 00Z GFS ENSEMBLE MEMBERS/UKMET/CNDN MODELS SHOW SYS REMAINING FARTHER S. CONSIDERING BLOCKING HUDSON BAY HI PRES AND LATEST TRENDS CONCERNING UPCOMING STORM THIS WEEKEND...TEND TO FAVOR THE SRN TRACK SCENARIO. HOWEVER...WL FOLLOW LATEST NCEP GUIDANCE... WHICH FAVORS A TRACK FARTHER TO THE NW...GIVEN UNCERTAINTY. HAVE MAINTAINED CHC POPS FOR NOW WITH MIXED PCPN PSBL OVER THE SCNTRL. COORDINATED WITH GRB/DLH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ROLFSON (UPDATE) KF (SHORT TERM) KC (LONG TERM)
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
410 PM EST THU FEB 22 2007 .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED A DEPARTING MID/UPPER LEVEL LOW OVER GEORGIAN BAY. A BROAD RDG WAS LOCATED OVER THE WRN PLAINS DOWNSTREAM FROM THE NEXT SIGNIFICANT TROF MOVING ONSHORE INTO THE WRN CONUS. AT THE SFC...NNW FLOW PREVAILED ACRS THE CWA BTWN LOW PRES OVER LAKE ONTARIO AND A RDG FROM NRN ONTARIO/MANITOBA INTO WRN MN. AS THE 850-700 MOISTURE HAS THINNED OUT...PER KSAW TAMDAR SNDGS...THE MULTIPLE WIND PARALLEL LES BANDS HAVE DIMINISHED DURING THE AFTERNOON. THE HIGHEST REFLECTIVITIES REMAINED OVER ERN MARQUETTE AND WRN ALGER COUNTIES. THE LES HAS ALSO DIMINISHED OR ENDED OVER THE WEST AS THE VIS LOOP SHOWED THE BACK EDGE OF THE LAKE CLOUDS HAD ALMOST MOVED ONSHORE. LES BANDS HAD ALSO THINNED OUT OR DISSIPATED E OF MUNISING. .SHORT TERM (TONIGHT AND FRI)... MAIN FCST CONCERNS ARE LES TRENDS. SATELLITE AND RADAR TRENDS ALONG WITH THE 12Z/18Z NAM AND LCL HIRESWRF-ARW SUGGEST THAT THE REMAINING LES BANDS WILL CONTINUE TO WEAK AND GRADUALLY SHIFT SHIFT INTO N CNTRL UPR MI THIS EVENING AS THE WINDS BACK NE. HOWEVER...WITH INVERSION HEIGHTS FALLING AOB 3K FT AND CONTINUED 850-700 DRYING...LITTLE MORE THAN SCT LIGHT SNOW SHOWERS OR FLURRIES ARE EXPECTED BY LATE THIS EVENING. ANY ADDITIONAL ACCUMULATIONS SHOULD BE LESS THAN AN INCH. WITH ENOUGH CLEARING INLAND ALONG WITH LIGHT WINDS...TEMPS SHOULD FALL CLOSE TO 0F. OTHERWISE...LAKE CLOUDS WILL KEEP MIN TEMPS FROM DROPPING OFF AS MUCH N CNTRL. EXPECT INCREASING MID/HIGH CLOUDS FROM SW TO NE WITH WAA PATTERN AHEAD OF THE DEVELOPING WRN CONUS TROF. DIVERGENT ACYC NRLY FLOW WITH INVERSION HEIGHT BLO 3K FT SHOULD MINIMIZE POTENTIAL FOR ANY LINGERING LIGHT LES EVEN THOUGH SOME LAKE CLOUDS MAY LINGER OVER N CNTRL UPR MI. .LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... TAKING A LOOK AT THE 500MB ANALYSIS OVER THIS PERIOD...WE WILL START OUT WITH THE HIGH AMPLITUDE RIDGE SITUATED FROM NORTHCENTRAL MANITOBA THROUGH KDLH...AND INTO WESTERN ILLINOIS. THIS RIDGE SHOULD BE OVERHEAD...OVER THE UPPER PENINSULA 06Z SATURDAY THROUGH 06Z SUNDAY. DURING THIS SAME TIME WE WILL BE MONITORING THE FORMATION OF THE CUT OFF LOW ACROSS THE DESERT SOUTHWEST. CONTINUE TO SEE SOME MODEL CHANGES OVER THE PAST 24 HOURS...BUT MODEL TO MODEL CONSISTENCY SEEMS TO REMAIN PRETTY GOOD. AS A RESULT...CONTINUED TO SIDE CLOSE TO THE GFS AND ECMWF WHICH SEEMED TO BE MORE IN LINE WITH EACH OTHER OVER THE PAST COUPLE OF RUNS THAN 24 HOURS AGO. SO...WITH FUTURE FORECAST ISSUANCES WE WILL LIKELY NEED TO DECIDE ON WHERE TO ISSUE A WATCH...FOR SNOW. JUST A FEW DAYS AGO WE WERE FIGURING THAT SOME MIXED PRECIPITATION WOULD BE EXPECTED OVER THE UPPER PENINSULA THIS WEEKEND. NOW...WITH THE LOW SHIFTED FURTHER AND FURTHER TO OUR SOUTH...ALL SNOW IS NOW FORECAST...WITH THE HIGHEST AMOUNTS REMAINING ACROSS THE SOUTHERN HALF OF THE CWA...THAT IS UNTIL THE COLD ENOUGH AIR WRAPS BACK INTO THE AREA TO ALLOW FOR LAKE EFFECT OR LAKE ENHANCEMENT SUNDAY NIGHT INTO MONDAY ALONG WITH MORE FAVORABLE WINDS. AFTER OUR CLOUDY AND WET WEEKEND...WE ARE FIGURING MOST OF MONDAY NIGHT THROUGH TUESDAY NIGHT TO BE DRY. YET ANOTHER SYSTEM WILL SWEEP IN FROM THE SOUTHWEST FOR MID WEEK INTO THE END OF THE WORK WEEK. TIMING ON THIS ONE WILL LIKELY CHANGE OVER THE NEXT COUPLE OF DAYS...AND MAY BE SLOWER THAN WHAT WE CURRENTLY HAVE...GIVEN THE LARGE RIDGE IN BETWEEN THE TWO STORM SYSTEMS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ .SHORT TERM...JLB .LONG TERM...KF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1205 PM EST THU FEB 22 2007 .UPDATE... EVEN THOUGH A TIGHT PRES GRADIENT STILL WAS IN PLACE OVER THE SE HALF OF UPPER MI WINDS HAVE DIMINISHED A BIT AS THE 8 MB/3 HR PRES RISE MAX HAS SHIFTED E OF LAKE SUPERIOR. THEREFORE...THE WIND ADVISORY FOR THE SOUTH HAS BEEN DROPPED. LAKE EFFECT SNOW SHOWERS ALIGNED WITH CYCLONIC NNW CBL FLOW HAVE ALSO DIMINISHED AS THE DEEPER MOISTURE BEHIND THE MID LEVEL LOW DEPARTS AND TEMP AT THE TOP OF THE 4K FT INVERSION WAS ONLY NEAR -14C(16Z KSAW TAMDAR SDNG). HOWEVER...SOME BANDS COULD STILL DROP VSBYS BLO 1SM DURING THE EARLY AFTERNOON AND PRODUCE ADDITIONAL ACCUMULATIONS AROUND AN INCH. .PREV DISCUSSION...ISSUED 600 AM EST THU FEB 22 2007 MAIN FCST ISSUES IN SHORT TERM ARE STRONG WINDS...LES AND BLOWING SNOW ON BACKSIDE OF PACIFIC LOW WHICH HAS NOW DEPARTED E OF FCST AREA. LONGER TERM FOCUSES ON STORM PROJECTED TO LIFT OUT OF THE SRN PLAINS ON SAT AND HOW MUCH OF AN IMPACT IT WILL HAVE ON UPR MI/S WX OVER THE WEEKEND. LATEST WATER VAPOR IMAGERY AND RUC ANALYSIS REVEALS THAT POTENT SHORTWAVE HAS MOVED E OVER NRN LAKE MI WITH ASSOC SFC LOW LOCATED E OF SAULT STE MARIE. SHORTWAVE HAD A 12HR 500MB HEIGHT FALL OF 70M AS IT PASSED OVER KDLH EARLIER LAST EVENING (00Z). ARCTIC COLD FRONT HAS PASSED THROUGH ENTIRE FCST AREA PROPELLED BY IMPRESSIVE 7MB/3HR PRES RISE MAX NOW OVER WRN LAKE SUPERIOR WITH GOOD ISALLOBARIC COMPONENT TO PREVAILING WIND FROM KEWEENAW PENINSULA INTO NCNTRL UPR MI. TODAY...NORTH WINDS HAVE ALREADY GUSTED AT OR NEAR ADVISORY CRITERIA (45 MPH) OVER PORTIONS OF THE KEWEENAW PENINSULA THIS MORNING. WOULD EXPECT THESE STRONG NORTH WINDS TO OCCUR OVER THE REST OF CENTRAL AND ERN UPR MI WITHIN THE NEXT FEW HOURS AS THE PRES RISE MAX MOVES SE ACROSS NRN AND ERN UPR MI. RADAR SHOWS DEFORMATION/COMMA HEAD PCPN WRAPPING INTO FCST AREA WITH STRONG N-NW WINDS BEHIND SYSTEM. CONVERGENT NNW FLOW AND UPSLOPE COMPONENT TO WIND WILL ENHANCE SNOW ACCUMS FOR HIGHER TERRAIN ALONG LAKE SUPERIOR. 850 MB TEMPS LOWERING TO -15C BY MIDDAY ALONG WITH CONTINUED CYCLONIC FLOW WILL ALSO ALLOW FOR LES BANDS TO DEVELOP AS SYNOPTIC SNOW LIFTS E. LES WILL TAPER OFF LATE AS FLOW BECOME MORE ANTICYCLONIC WITH RDGG FROM THE WEST. GIVEN STRONG WIND AND SNOW EXPECTED TO CONTINUE INTO EARLY AFTERNOON I EXTENDED SNOW AND BLOWING SNOW ADVISORIES FOR COUNTIES E OF MQT UNTIL 4 PM EST. SNOW AND BLOWING SNOW ADVISORIES FOR W AND NCNTRL COUNTIES SHOULD END BY LATE MORNING AS GRADIENT SUBSIDES FROM THE W. EXPECT ADDITIONAL SNOW ACCUMS OF 1-3 INCHES FOR THE S/BS ADVISORIES. SSUED WIND ADVISORIES FOR SNCTRL COUNTIES UNTIL LATE MORNING AS WELL. WEAKENED N-NE FLOW WITH BUILDING SFC RDG ALONG WITH INVERSION HGTS LOWERING BLO 3KFT WILL TAPER ANY REMAINING LES TO FLURRIES ALONG NCNTRL AND WRN COUNTIES. HIGH PRESSURE BUILDING OVERHEAD WILL RESULT IN DRY CONDITIONS FRI INTO FRI NIGHT OVER MOST OF FCST AREA. MODELS STILL UNCERTAIN ON TRACK OF DEVELOPING SRN PLAINS STORM BUT ALL MODELS SEEM TO BE TRENDING MUCH SLOWER AND MUCH FARTHER S WITH SYSTEM. LATEST GFS AND ECMWF INDICATE STORM WILL TRACK OVER FAR SRN LWR MI SUN NIGHT AND LATEST 00Z ENSEMBLE MEMBERS SEEM TO ALSO SUPPORT SIMILAR TRACK. A TRACK THIS FAR SOUTH WOULD NOT BODE WELL FOR HEAVY SNOW OVER UPR MI...AND WOULD LIKELY FAVOR CENTRAL LOWER MI FOR HEAVIEST SNOWFALL. 00Z UKMET LOOKS TO BE EVEN FARTHER SOUTH WITH SYSTEM THAN GFS/ECMWF SHOWING CLOSED 5H LOW OVER KS/OK BDR BY 00Z SUN. UKMET EVEN HAS LOOK THAT 5H LOW WILL CUT OFF AND SLIDE WELL SOUTH AS 5H RDG DOMINATES OVER THE WRN GREAT LAKES THROUGH WEEKEND. CANADIAN MODEL TRACK WITH SYSTEM LOOKS MORE LIKE GFS/ECMWF BUT PREFER ITS QPF FIELD OVER GFS AND NAM. NAM AND GFS LOOK TO BE TOO FAR NORTH WITH MOISTURE/PCPN BRINGING PCPN INTO SW COUNTIES LATE FRI NIGHT AND THEN SPREADING QPF INTO CENTRAL COUNTIES ON SAT. PREFER DRIER CANADIAN GIVEN STRENGTH OF RDGG FROM HUDSON BAY HIGH AND ASSOC ANTICYCLONIC FLOW. ECMWF MOISTURE FIELDS ALSO SUPPORT DRIER FCST FOR FRI NIGHT INTO EARLY PART OF NEX WEEK. THUS HAVE TRENDED BACK POPS FOR SNOW OVER SRN AND WRN FCST AREA SAT AND REMOVED MENTION OF SNOW FROM NCNTRL AND ERN FCST AREA. ALSO TRENDING BACK POPS FOR SNOW OVER NCNTRL AND WRN FCST AREAS SAT NIGHT INTO SUN. MODELS ALSO SEEM TO BE TRENDING THAT SYSTEM WILL WEAKEN AND MOVE WELL E OF FCST AREA MON NIGHT INTO TUE WITH RDGG MOVING IN FM W SO HAVE ALSO LOWERED OR REMOVED POPS FOR THE EARLY PART OF WEEK. FOR NOW...WILL ADJUST WORDING IN UPDATED HWO TO DOWNPLAY THREAT OF HEAVY SNOW. MODELS SHOULD COME INTO EVEN BETTER AGREEMENT ON EVOLUTION AND TRACK OF SYSTEM AS SHORTWAVE ENERGY MOVES ONSHORE FROM THE ERN PACIFIC. && .MQT WATCHES/WARNINGS/ADVISORIES... SNOW AND BLOWING SNOW ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MIZ006-007-014-085. SNOW AND BLOWING SNOW ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR MIZ005. && $$ JLB
AREA FORECAST DISCUSSION
NWS SEATTLE WA
830 PM PST FRI FEB 23 2007 .SYNOPSIS...A VIGOROUS FRONTAL SYSTEM WILL SWEEP THROUGH WESTERN WASHINGTON LATER TONIGHT THROUGH SATURDAY MORNING. A COLD UPPER LEVEL TROUGH WILL REMAIN IN THE NORTHEAST PACIFIC INTO THE FIRST PART OF NEXT WEEK...FOR COOL SHOWERY AND AT TIMES BLUSTERY WEATHER. && .SHORT TERM...VIGOROUS FRONT THRU WESTERN WA OVERNIGHT THROUGH SATURDAY MORNING. ANOTHER BATCH OF COLD AIR ALOFT WILL DIG INTO THE NORTHEAST PACIFIC OVER THE WEEKEND...AN UPPER RIDGE BUILDS OUT AROUND 170W AND A BROAD TROF SETTLES IN THE NE PAC. WASHINGTON WILL BE ON THE COOL SIDE OF THE POLAR JET FOR AT LEAST THE NEXT SEVERAL DAYS. IT WILL BE WINDY WITH THE FRONT LATE TONIGHT AND SATURDAY MORNING IN MANY AREAS...ESPECIALLY OVER THE MARINE ZONES...AND BLUSTERY AT TIMES RIGHT THROUGH MONDAY AS SEVERAL SURFACE TROFS COME IN. LATE TONIGHT...THE HILLS AROUND HOODSPORT AND LAKE CUSHMAN MAY SEE SNOW FOR A FEW HOURS...BUT A QUICK CHANGE TO RAIN AT DAYBREAK IS A GOOD BET AND THE MM5 SNOW ACCUM FCST THERE LOOKS OVERDONE. H850 TEMPS WILL RISE TO AROUND 0C ON SATURDAY OVER THE OLYMPICS AND BY AFTERNOON OUR FCST SNOW LEVEL IS ACTUALLY TOO LOW. FOR NOW...THE SNOW LEVEL FCST TONIGHT IS 1000FT AND THAT LOOKS GOOD TIL FROPA SAT MORNING...THE CURRENT ACARS FREEZING LEVEL OVER PUGET SOUND IS 2200FT. && .AVIATION...CONDITIONS DETERIORATE OVERNIGHT AS WARM ADVECTION WITH A VIGOROUS FRONTAL SYSTEM INCREASES. WILL UPDATE THE AVIATION AFD BY 930 PM. .AVALANCHE...ABUNDANT LOW DENSITY SNOW RECEIVED DURING PAST FEW DAYS WITH SEVERAL BURIED WEAK LAYERS. WHILE MUCH OF THIS RECENT SNOW HAS BEGUN TO STABILIZE, DECENT INCOMING STORM ON SATURDAY SHOULD BE ACCOMPANIED BY MODERATE TO STRONG WINDS, SLIGHT WARMING AND MODERATE TO LOCALLY HEAVY SNOWFALL ESPECIALLY NEAR THE VOLCANOES. THIS SHOULD LOAD AND STRESS EXISTING SNOWPACK WITH HIGHER DENSITY WIND SLABS. ISSUED AVALANCHE WATCH THIS MORNING TO HIGHLIGHT UPCOMING SIGNIFICANT DANGER INCREASE TO RELATIVELY LOW ELEVATIONS ON SATURDAY, AND WILL PROBABLY ISSUE WARNING EARLY SATURDAY. WITH MORE SNOWFALL AND ANOTHER, THOUGH WEAKER, SYSTEM EXPECTED SUNDAY, EXPECT ONLY MINOR DANGER DECREASE THROUGH THE WEEKEND AND HOPE THAT BACK COUNTRY FOLKS WILL HEED THE WARNING AND TRAVEL ON MORE GENTLE TERRAIN FOR AWHILE. FOR DETAILS SEE WWW.NWAC.US. MOORE THIS SECTION IS PROVIDED IN PARTNERSHIP WITH THE USDA FOREST SERVICE NW WEATHER AND AVALANCHE CENTER. THIS IS THE DEBUT OF THIS SECTION AND WILL BE PROVIDED ON AN EVENT DRIVEN BASIS. && .SEW WATCHES/WARNINGS/ADVISORIES... ...GALE WARNING FOR THE COAST...WEST ENTRANCE...EAST ENTRANCE... ADMIRALTY INLET...AND THE NORTHERN INLAND WATERS... ...SMALL CRAFT ADVISORY CENTRAL STRAIT...PUGET SOUND AND HOOD CANAL ...SMALL CRAFT ADVISORY FOR ROUGH BAR CONDITIONS GRAYS HARBOR BAR... $$ WEATHER.GOV/SEATTLE
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1100 PM CST FRI FEB 23 2007 .UPDATE... 600 PM CST SENT QUICK UPDATE TO THE ZONES AND GRIDS. REFER TO THE AVIATION DISCUSSION BELOW FOR DETAILS. && .DISCUSSION...AFTERNOON FORECAST... 230 PM CST INITIAL ROUND OF MID LEVEL WARM ADVECTION SENDING A PLUME OF CLOUDS ACROSS FCST ARE THIS AFTERNOON. ASIDE FROM PUTTING A LID ON TEMPERATURE RISE LOW LEVEL DRYNESS HAS PRECLUDED ANY SFC PRECIP. UPPER TROUGH AND SURFACE FRONT MOVING INTO WRN COLO THIS AFTERNOON AND WARM INCRESINGLY MOIST AIRMASS ADVECTING N INTO CENTRAL PLAINS. SFC LO EXPECTED TO FORM OVER THE WESTERN HIGH PLAINS OF COLO-KANSAS TONIGHT AND TRACK NE TOWARD MID MISS VALLEY SAT INTO EARLY SUNDAY. MODELS SUGGEST THIS SYSTEM WILL RAPIDLY OCCLUDE AND ACTURALLY BEGIN DECAY/FILLING PROCESS AS IT REACHS LOWER WESTERN LAKES SUNDAY. LOW LEVELS AS SAMPLED BY TAMDAR FLIGHTS IN CENTRAL IL ARE VERY DRY AND SE WINDS CONTINUE TO ADVECT TEENS DEW PTS INTO REGION THIS AFTERNOON. NEW GFS HAS COME INTO PHASE WITH NAM AND OTHER MODELS IN SLOWING ONSET OF APPROAHING LOW AND PRECI UNTIL LATER SAT. THE UPSHOT OF ALL THIS IS AN EXPECTED BEGINNING OF PRECIP SAT AFTN OVER NWRN IL SPREADING INTO NW IN AFTER SUNSET. LOW DEW POINT AIR AND DRY LOWER LEVELS INDICATE AN INITIAL LOW WET BULB /BELOW FREEZING/ CONDITION TO BEGIN ANY PRECIP AS SNOW. WIND FIELD AROUND APPROACHING LOW WILL INCR RAPIDLY LATER SAT AND SAT NIGHT WITH VERY WELL DEVELOPED WARM ADVECTION SIGNAL SEEN IN MODEL SOUNDINGS AFTER 00Z SUN /6PM SAT/. THIS SIGNAL IS IN VICINITY OF THE TROWAL FEATURE OF THE OCCLUSION AND PRONE TO THE MOST INTENSE PRECIP. MODEL SOUNDINGS ALSO REVEAL THE TEMPERATURE PROFILE TO HOVER AROUND 0 DEG C BELOW 850MB OVER AT LEAST THE NRN HALF OF THE FCST AREA INTO SUNDAY MORNING WHICH SUPPORTS A MIXED PRECIP WITH THE POTENTIAL FOR SIGNIFICANT FRZG RAIN OR SLEET. SNOW MAY DOMINATE TOWARD THE WISC BORDER WITH GRID TOTAL OF 5-7 INCH STORM TOTAL REFLECTING THE INITIAL GUESS. ELSEWHERE ACCUMULATIONS OF SLEET AND SOME FREEZING RAIN WILL REDUCE TOTALS. RAIN WILL LIKELY DOMINATE SOUTH OF THE KANKAKEE RIVER TOWARD PONTIAC. MOST CONCENTRATED PRECIP PERIOD APPEARS TO BE BETWEEN 6PM SAT AND 6AM SUN WITH RESIDUAL SNOW CONTINUING SUNDAY. AS UPPER TROUGH WEAKENS OVERHEAD AND SLOWLY RECEDES TO THE EAST PERIODS OF LIGHT SNOW ARE EXPECTED TO PERSIST INTO MON AND TUE. ANOTHER HIGH AMPLITUDE UPPER TROUGH MOVING ONTO THE WEST COAST AT MIDWEEK WILL KICK OFF ANOTHER PLAINS CYCLONE ABOUT THURS WITH A MODEST WARM UP TOWARD THE END OF THE WEEK. TEMPS TONIGHT WILL BE MODIFIED BY CLOUDS ALTHOUGH IF CLOUDS THIN LATER IN THE NIGHT DRY AIR MAY ALLOW BRIEF DIP..BUT WILL GO ABOVE GUIDANCE PLAYING FOR CLOUDS. THIS SYSTEM HAS THE POTENTIAL TO BE A SIGNIFICANT PRECIPITATION PRODUCER GIVEN THE SLOWING NATURE OF MOVEMENT AS IT APPROACHES. PRECIP TYPE UNCERTAINTY IS A CONCERN ALTHOUGH THAT MAY BE OFFSET SOME BY THE SE TRAJECTORY OF THE INCOMING AIRMASS..AS OPPOSED TO A NE COMPONENT. SNOW TOTALS GOING NORTH TOWARD THE WISC BORDER WILL INCREASE RAPIDLY ESPECIALLY NORTH OF THE BORDER. WHILE THE OVERALL SCENARIO HAS BECOME MORE CLEAR THE DETAILS OF PRECIP TYPE IS A LINGERING CONCERN KML && .AVIATION... 1100 PM CST 06Z TAFS...BAND OF -SN PASSING JUST NORTH OF ORD ATTM...WITH NO RADAR ECHOES UPSTREAM ACROSS CENTRAL IL AND MO. WINDS HAVE TURNED A BIT MORE EASTERLY IN THE LAST FEW HRS...SO EXPECT MVFR CIGS COMING OFF LAKE MICHIGAN TO HOLD NORTH OF ORD THROUGH THE REST OF THE NIGHT. WINDS INCREASE SHARPLY TOMORROW OUT OF THE EAST AS LOW PRESSURE RAPIDLY DEEPENS OVR KS AND SFC HIGH REMAINS OVR ONTARIO. WARM AND VERY MOIST AIR ADVECTING NWD OVR THE COOL AND DRIER SFC LAYER LATE SAT AFTN SHOULD ALLOW SOME -FZDZ TO DEVELOP LATE SAT AFTN. FCST SOUNDINGS ARE INDICATING TEMPS RIGHT NEAR THE 0 DEG C ISOTHERM THROUGH SAT EVENING. THERE IS SOME QUESTION AS TO WHETHER THE STRENGTH OF LOW LEVEL WARM AIR SURGING NORTHWARD IN 75KT H8 JET WILL PUSH TEMP PROFILES ABV FREEZING. THUS...KEPT P-TYPE FZRA FOR THE CHICAGO AREA TERMINALS FROM 23Z THROUGH 06Z AND INDICATED A MIX OF FZRASNPL FOR RFD FOR THE SAME TIME FRAME. STRONGLY FORCED BAND INDICATED BY THE MODELS SHOULD CROSS THE AIRPORTS BTWN 03-06Z. THE DEEPER CONVECTION ASSOCIATED WITH THIS BAND SHOULD ALLOW MORE PL FOR A PERIOD AND PERHAPS MDT SN/PL AT RFD WHERE TEMPS WILL BE A FEW DEGREES COOLER. HANDEL && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...WINTER STORM WATCH 18Z SATURDAY TO 00Z MONDAY WINNEBAGO BOONE MCHENRY LAKE COOK DUPAGE KANE DEKALB OGLE LEE LASALLE KENDALL GRUNDY WILL. .IN...WINTER STORM WATCH 18Z SATURDAY TO 00Z MONDAY LAKE PORTER. .LM...GALE WRNG ALL LM AND NR SHORES 21Z SAT TO 21Z SUN.. && $$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
312 AM EST SAT FEB 24 2007 .SHORT TERM... SKIES ARE MO CLOUDY ATTM. REGIONAL RADARS SHOWS A LARGE ARC OF SNOW STRETCHING ACROSS SOUTHERN WISCONSIN. THIS SNOW IS CONVECTIVE IN NATURE AS LIGHTNING HAS BEEN EMBEDDED WITH IT MUCH OF THE NIGHT. KGRR-88D SHOWS SNOW ALOFT TRYING TO MOVE INTO THE SOUTHWEST CWA. TAMDAR SOUNDINGS FROM A CHI-MKG LINE SHOW VERY DRY AIR IN PLACE AND THIS PCPN WILL HAVE DIFFICULTY MAKING INTO THE CWA. NONTHELESS...BEH JUST DROPPED TO 5SM -SN. SFC ANALYSIS SHOWS LOW PRESSURE IN COLORADAO. CONVECTION STRETCHES FROM THE RED RIVER TO THE RED RIVER OF THE NORTH. THIS CONTINUES TO BE A DYNAMIC SYSTEM AND IS THE FOCUS OF THE SHORT TERM. GFS/NAM CONTINUE TO SHOW THE LOW MOVING ENE THROUGH KANSAS BEFORE TURNING NORTHEAST AND MOVING TOWARD THE SOUTHERN CWA LATE SUNDAY. THE GULF IS WIDE OPEN IN FRONT OF IT AND WILL SUPPLY AN AMPLE SOURCE OF MOISTURE. THERE IS A LARGE AREA OF PCPN ATTM STRETCHING FROM WISCONSIN SOUTHEAST TO SOUTHERN LAKE MICHIGAN. THIS PCPN IS BEING GENERATED BY STRONG ISENTROPIC LIFT. CONDENSATION PRESSURE DEFICITS FALL TO NEAR 0MB THIS MORNING OVER THE WESTERN CWA. WILL ADD A CHC OF SNOW TO THE SOUTHWEST CWA THIS MORNING. THE GFS ENSEMBLES ARE IN CLOSE AGREEMENT ON THE TRACK OF THE LOW AND LINE UP WITH THE NAM TOO. THOSE SOLUTIONS TAKE THE LOW ACROSS SBN TO DTW. THAT WOULD PLACE THE HEAVIEST SNOW ACROSS THE NORTHERN CWA. FCST SOUNDINGS SHOW THE POTENTIAL FOR SOME IP TO DEVELOP OVER THE SOUTHERN CWA AS THE NOSE OF WARM AIR NEAR 800 MB TOUCHES THE 0C MARK. LATEST 20KM WRF AND GLBL GEM ARE SIMILAR TO THE GFS IN BRINGING PCPN INTO THE SOUTHWEST CWA THIS EVENING AND COVERING MUCH OF THE CWA BY 06Z. WITH THAT IN MIND WILL BUMP UP THE START TIME OF THE WINTER STORM WATCH OVER THE NORTHERN 2/3 OF THE CWA TO MATCH THE SOUTHERN CWA...06Z. THE NAM SEEMS A BIT WET GIVEN THE WEAKENING NATURE OF THE SYSTEM. BUT THERE ARE SOME STRONG DYNAMICS IN THE FORM OF 850-500 MB FGEN FORCING TO KEEP THE SYSTEM GOING. ONE THING THAT STILL IS TROUBLING IS THAT THE TIP OF THE DRY SLOT IS STILL PROGD TO MOVE THROUGH THE CWA LATE SUNDAY MORNING AND EARLY AFTERNOON WITH DEEPER MOISTURE MOVING BACK IN LATE SUNDAY AND SUNDAY NIGHT. THUS...THERE LOOKS TO BE TWO PERIODS OF PCPN WITH A LULL IN BETWEEN. GFS SNOW AMOUNTS LOOK GOOD WITH TOTALS FROM THIS EVENING THROUGH SUNDAY EVENING 6-8 INCHES...AND THEN ANOTHER 2 TO 4 SUNDAY NIGHT. THE UPPER LOW REMAINS OVER LOWER MICHIGAN THROUGH MONDAY. SO THIS COULD BE A PROLONGED SNOW EVENT. WINDS WILL STILL BE A FACTOR. BUFKIT WIND PROFILE SHOWS 40 KT WINDS AROUND 1K FEET AT 12Z SUNDAY. I DON/T THINK WE/LL BE ABLE TO TAP ALL OF THAT AT THAT TIME OF DAY BUT GUSTY WINDS WILL CREATE A HAZARD. WOULDN/T BE SURPRISED TO SEE VISIBILITIES DROP TO A HALF MILE AT TIMES. WITH THE UPPER LOW IN PLACE...MORE SNOW IS EXPECTED MONDAY. QPF AROUND A TENTH OF AN INCH WOULD SUGGEST ANOTHER 1-3 INCHES. .LONG TERM... NO CHANGES MADE IN THE EXTENDED PORTION OF THE FORECAST (FROM MONDAY NIGHT THROUGH THE END OF THE WORK WEEK). STACKED LOW WILL STILL BE SITUATED OVER THE AREA MONDAY NIGHT...BUT IT WILL HAVE WEAKENED SUBSTANTIALLY BY THIS POINT. USED THE GFS FOR GUIDANCE. GIVEN ITS SOLUTION...THE SURFACE LOW WILL HAVE RISEN TO 1003MB/S BY MONDAY EVENING. IT CONTINUES TO WEAKEN AND SLIDE EAST WITH TIME INTO TUESDAY. MAINTAINED THE CHANCES FOR LIGHT SNOW BOTH MONDAY NIGHT AND TUESDAY AS THERE SHOULD BE SOME LINGERING LIGHT SNOW...JUST NOT EXPECTING A WHOLE LOT OF ACCUMULATION IN THIS TIME FRAME. TUESDAY NIGHT SHOULD BE A COLD NIGHT GIVEN SURFACE RIDGING IN PLACE AND A FRESH SNOWPACK. THE MIDDLE OF THE WEEK WILL SEE A SHORT RESPITE TO THE WX...BEFORE OUR NEXT SYSTEM APPROACHES FROM THE WEST WEDNESDAY NIGHT. WE MAY NEED TO ADD PRECIPITATION TO THE FORECAST WEDNESDAY NIGHT WITH STRONG WARM AIR ADVECTION ONGOING. THURSDAY AND THURSDAY NIGHT MAY BE TRENDING MORE TOWARD RAIN AS WELL...AS 850MB TEMPS RISE TO AROUND +6 C. COLDER AIR SWEEPS IN BEHIND A FRONTAL PASSAGE ON FRIDAY. $$ && .GRR WATCHES/WARNINGS/ADVISORIES...WINTER STORM WATCH FOR THE ENTIRE CWA FROM 1 AM SUNDAY THROUGH 7 AM MONDAY. && $$ 93 DUKE
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
1153 PM CST FRI FEB 23 2007 .UPDATE... SNOW FALLING GENERALLY NEAR THE -2 850 MB ISOTHERM AND 1540-1544 850-700 MB THICKNESS..WHICH ARCS FROM SW WI/SE MN TO NEAR THE MSP AREA AND THEN INTO WEST CENTRAL MN. MAIN ISEN LIFT ON 295 SURFACE WILL STILL BE FOCUSING OVER SE MN AND WEST CENTRAL WI OVERNIGHT...BUT SOME REGENERATION A LITTLE FARTHER WEST LATER TONIGHT. THIS WILL CUT BACK ON SNOW AMOUNTS OVER MN PART OF CWA...BUT POSSIBLY A LITTLE MORE THAN EARLIER THOUGHT INTO CENTRAL MN NORTHEAST OF KSTC. LOW LEVEL JET WEAKENING SLIGHTLY TOWARD MORNING AS UPPER HEIGHT FALLS FORCE LOW LEVEL CIRC FARTHER SOUTH. WILL EMPHASIZE MORE FREEZING PRECIP IN SOUTH CENTRAL AND SOUTH WEST MN OVERNIGHT AND A LITTLE FATHER NORTH AS WELL. LATER PERIODS SOMEWHAT OF A QUESTION...BUT LESS SNOW TONIGHT WILL CUT BACK ON GRAND TOTALS. A QUICK LOOK AT 200 MB TEMP PATTERN SUGGESTS HEAVY SNOW POTENTIAL STILL THERE WITH STRONG WARM ADVECTION INTO SOUTHERN MN ON SATURDAY INTO SATURDAY NIGHT...ALTHOUGH 850 MB LOW TRACK OFF 00Z WRF-NAM A TOUCH TOO FAR SE FOR MAX SNOWS IN EAST CENTRAL MN. PREV DISCUSSION... /ISSUED 353 PM CST FRI FEB 23 2007/ DISCUSSION... LONG DURATION WINTER EVENT TO BEGIN THIS EVENING AND PERSIST INTO SUNDAY EVENING. PUT MORE WEIGHT ON THE GFS TODAY WHICH WOULD FAVOR 12 TO 15 INCHES OVER THE TWIN CITIES AS WELL AS TO THE SOUTH AND EAST. EVEN THE FAR WESTERN AND NORTHERN AREAS OF THE CWA SHOULD SEE 8 TO 12 INCHES BY THE TIME THE EVENT ENDS. MUCH OF THIS SNOW IS EXPECTED SATURDAY NIGHT AND SUNDAY MORNING. IN THE MEAN TIME...THE REAL CHALLENGE IS GETTING THROUGH TONIGHT AND SATURDAY. SOME THUNDERSTORMS HAVE DEVELOPED JUST SOUTHWEST OF FAIRMONT AT MID AFTERNOON. WILL INCLUDE A CHANCE OVER SOUTH CENTRAL THIS EVENING IN ZONE OF STRONG THETA-E ADVECTION. AT THE SAME TIME... TEMPERATURES AT THE SURFACE ARE AT OR BELOW FREEZING. COBB BUFKIT DATA FROM THE GFS SHOWS FREEZING RAIN DEVELOPING ALONG AND SOUTH OF THE MINNESOTA RIVER THIS EVENING AND PERSISTING OVER FAR SOUTH CENTRAL AREAS EARLY SATURDAY MORNING. SOME SLEET EXPECTED TO OCCUR WITH THE SNOW FROM THE TWIN CITIES ON WEST TONIGHT. INCREASED POPS FROM CHANCE TO CATEGORICAL AS THE NIGHT PROGRESSES. ICE AMOUNTS OF A QUARTER TO A HALF INCH POSSIBLE FAR SOUTH. A LULL IN THE ACTION EARLY ON SATURDAY AS THE FIRST ROUND OF THETA-E ADVECTION MOVES EAST OF THE CWA AND A SECOND ROUND DEVELOPS OVER IA ASSOCIATED WITH THE CLOSED LOW DEVELOPING TO OUR SOUTH. LATE SATURDAY AND SATURDAY NIGHT THE DIFFERENTIAL DIVERGENCE INCREASES DRAMATICALLY OVER US AND TO THE SOUTHEAST. THIS IS ALSO ALONG THE AXIS OF BEST MOISTURE FLUX IN THE 850-700MB LAYER. HENCE...THIS PERIOD LOOKS THE BEST FOR MODERATE TO HEAVY SNOW. THE SNOW WILL DIMINISH OVER WESTERN MN SUNDAY MORNING BUT WEST CENTRAL WI STILL LOOKS GOOD FOR MORE ACCUMULATING SNOW BEFORE IT TAPERS OFF IN THE AFTERNOON. BLOCKING THAT DEVELOPS TO THE NORTHEAST OF THE LOW PRESSURE SYSTEM WILL KEEP US IN CLOUDS AND LIGHT SNOW INTO MONDAY. LONGER TERM...GFS/ECMWF SHOW ANOTHER STORM SYSTEM FOR LATE NEXT WEEK. && AVIATION... PRECIP WILL CONTINUE AND INCREASE IN INTENSITY DURING THE EARLY MORNING HOURS ACROSS TAF SITES. HEAVIEST SNOW IS EXPECTED OVER EAU GIVEN RADAR TRENDS WHICH REFLECT A BANDED NATURE TO THE HIGHEST ECHOES IN SW AND WRN WI. FOR MSP AND SATELLITE AIRPORTS UP TOWARDS STC AND AXN...A MIX IS MORE THAN LIKELY ESPECIALLY BEFORE SATURATED COOLING OCCURS. LATE EVE TAMDAR SOUNDINGS FROM BOTH MSP AND STC INDICATE A SUB FREEZING LAYER OF 3-4KFT AT THE SFC WITH HARDLY ANY ICE IN THE CLOUDS. TOP DOWN METHOD WOULD FAVOR ICE PELLETS MORE SO THAN FZRA...BUT FZRA HAS BEEN REPORTED IN SEVERAL OBS SO WILL LEAVE MENTION EARLY IN THE TAF. RWF BEING FURTHER SOUTH AND WEST WILL SEE ONLY IP AND FZRA THROUGH LATE SAT MORNING. ROUND TWO BEGINS SAT AFTN AT RWF AND AXN...AND SAT EVE OVER REST OF TAF SITES. DEFORMATION ZONE FROM PRIMARY SYSTEM ALONG WITH A TIGHTENING MID LEVEL BAROCLINIC ZONE WILL OFFER LIKELY POTENTIAL FOR MODERATE TO HEAVY SNOW. THIS IS SUPPORTED BY ENSEMBLE PROBABILISTIC FORECASTS FOR SAT NIGHT. IFR CONDITIONS WILL BE ON THE WAY WITH LIFR LIKELY AT TIMES AT RWF...MSP...AND EAU. AIRPORT WEATHER WARNING FOR MSP SEEMS LIKELY FOR SOMETIME DURING SAT EVE. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR BLUE EARTH-BROWN- CARVER-CHIPPEWA-DAKOTA-FARIBAULT-FREEBORN-GOODHUE-KANDIYOHI- LAC QUI PARLE-LE SUEUR-MARTIN-MCLEOD-MEEKER-NICOLLET- REDWOOD-RENVILLE-RICE-SCOTT-SIBLEY-STEELE-SWIFT-WASECA- WATONWAN-YELLOW MEDICINE COUNTY(IES). WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR ANOKA-BENTON- CHISAGO-DOUGLAS-HENNEPIN-ISANTI-KANABEC-MILLE LACS-MORRISON- POPE-RAMSEY-SHERBURNE-STEARNS-STEVENS-TODD-WASHINGTON- WRIGHT COUNTY(IES). WI...WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR BARRON-CHIPPEWA- DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX COUNTY(IES). && $$ JPR/RAH/MTF
AREA FORECAST DISCUSSION
NWS MIAMI FL
816 AM EST SAT FEB 24 2007 .UPDATE...A SCATTEROMETER PASS ACROSS THE AREA THIS MORNING SHOWS WINDS PREVAILING ACROSS THE ATLANTIC WATERS AT AROUND 15 KT AND 10 TO 15 KT ACROSS THE GULF WATERS. FOWEY ROCKS IS SHOWING INCREASING WINDS JUST OVER 15 KNOTS. THE MIAMI SOUNDING THIS MORNING AND ACARS DATA SHOW WINDS IN THE 15-17 KT RANGE BETWEEN 1-2K FT. SO WITH AN INCREASING PRESSURE GRADIENT TODAY...EXPECTING WINDS ACROSS THE COASTAL WATERS TO INCREASE TO 15 TO 20 KNOTS. THUS...UPDATED GRIDS/ALL PRODUCTS TO ACCOUNT FOR THIS. THIS WIND WILL RESULT IN A HIGH RISK OF RIP CURRENTS AT THE ATLANTIC BEACHES...AND A MARINE WX STMT WAS SENT TO HIGHLIGHT THIS. OTHERWISE...ANOTHER NICE DAY IS IN STORE FOR THE AREA...AS HIGH PRESSURE REMAINS IN CONTROL OF OUR WEATHER. NO OTHER SIGNIFICANT CHANGES TO THE FCST ARE ANTICIPATED THIS MORNING. /GREGORIA && .PREV DISCUSSION... /ISSUED 255 AM EST SAT FEB 24 2007/ DISCUSSION...HIGH PRESSURE RIDGE ORIENTED N-S FROM THE GREAT LAKES REGION TO THE ATLANTIC JUST E OF FLA ALONG WITH NEAR ZONAL UPPER FLOW CONTINUES TO DOMINATE OUR WEATHER. LARGE CUT OFF LOW DEVELOPING OVER THE CENTRAL PLAINS STATES WILL GRADUALLY MOVE NE DRAGGING A SFC FRONT INTO N FLA ON SUNDAY. THIS WILL SHOVE THE RIDGE TO THE EAST AND DOING SO WINDS WILL VEER TO THE E AND SE HELPING TO INCREASE LOW LEVEL MOISTURE. ALTHOUGH IT WILL TAKE AWHILE TO RECOVER FROM SUCH LOW DEW POINTS AS SEEN YESTERDAY AND HAVE THUS LOWERED SUNDAY POPS ACCORDINGLY. GFS HAS ALSO BACKED OFF ON THESE POPS. MOISTURE LEVELS WILL CONTINUE TO INCREASE THROUGH EARLY NEXT WEEK AND POPS WILL THEN BE ON THE INCREASE. ENOUGH INSTABILITY WILL EXIST BY TUESDAY KEPT THE WORDING OF SLIGHT CHANCE OF THUNDER IN THE ZONES. ALL OF THIS MATERIALIZES WITH THE SLOW SOUTHWARD MOVEMENT OF THE FRONT AND THE GFS CONTINUES TO STRUGGLE WITH JUST HOW FAR SOUTH THE FRONT WILL ACTUALLY GET. IT NOW BRINGS THE FRONT THROUGH S FLA ON WEDNESDAY WITH SOME SLIGHT DRYING AND A COUPLE OF DEGREES OF COOLING. SO WE SHALL SEE. AVIATION...VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD. THERE IS A POSSIBILITY OF OCNL MVFR VSBY CONDITIONS IN FOG AT TMB. LIGHT WIND FLOW AND SUFFICIENT TEMP/DEWPOINT SPREAD WILL HINDER FOG DEVELOPMENT. OTHERWISE, A SCATTERED FAIR WEATHER CUMULUS DAY WITH EAST WINDS UP TO 15 KNOTS. MARINE...WINDS WILL CONTINUE TO VEER TO THE SE THROUGH THE WEEKEND AND INCREASE IN SPEED AS THE GRADIENT TIGHTENS. SEAS WILL BEGIN AT LESS THAN 5 FEET AND THEN BUILD TO 6 FEET BY SUNDAY BEFORE SUBSIDING AGAIN NEXT WEEK WITH THE APPROACH OF THE FRONT. FIRE WEATHER...DEW POINTS HAVE SLOWLY RECOVERED FROM 24 HOURS AGO AND SHOULD CONTINUE TO DO SO. RH VALUES WILL DROP BELOW 40 PERCENT THIS AFTERNOON OVER GLADES AND HENDRY COUNTIES BUT THINKING IS THAT THEY WILL STAY ABOVE THE 35 PERCENT THRESHOLD. DEW POINTS WILL CONTINUE TO CLIMB INTO EARLY NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 76 66 81 69 / 0 - 10 20 FORT LAUDERDALE 77 68 81 69 / 0 - 10 20 MIAMI 76 64 82 69 / 0 - 10 20 NAPLES 80 63 81 68 / 0 - 10 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ LONG TERM...30/KOB SHORT TERM/AVIATION...18/GR
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
650 AM CST SAT FEB 24 2007 .UPDATE... 635 AM CST WE SAW THE OUTPUT FROM THE THE 06 UTC LOCALLY RUN WRF ARW MODEL WITH SOME ADVANCED PRECIPITATION PHYSICS. WE DECIDED TO UPDATE THE SNOW AMOUNTS AND TOTAL STORM ACCUMULATION FOR TONIGHT AND SUNDAY. && .DISCUSSION... 345 AM CST THIS IS A VERY DYNAMIC AND BAROCLINIC SURFACE CYCLONE DEVELOPING IN KANSAS. THERE IS STRONG WARM AIR ADVECTION EAST OF THE LOW WHICH IS IN WESTERN KANSAS. THUNDERSTORMS FROM OKLAHOMA TO WESTERN IOWA SHOW THE LARGE INSTABILITY. THE PROFILER WIND AT 300 MB AT 09 UTC SHOWS A 120 KNOT JET STREAK IN WEST CENTRAL TEXAS. WATER VAPOR LOOPS SHOW THE INTENSE CIRCULATION OVER SOUTHEAST COLORADO. WE EXPECT THIS SURFACE CYCLONE TO DEEPEN AND MOVE INTO SOUTHEAST IOWA BY 12 UTC SUNDAY. THE ACARS SOUNDING AT ORD SHOWS AN INVERSION AND THE STRONG WIND ABOVE 1400 FT FROM THE EAST. TAMDAR SOUNDING AT PIA AT 336 UTC SHOWS A DRY LAYER AROUND 900 MB. THIS DRY LAYER WAS UP TO 800 MB. AS THE LOW DEEPENS THE WIND WILL INCREASE DUE TO THE INCREASE IN THE PRESSURE GRADIENT. WE MAY HAVE WIND GUSTS TO 40 MPH IN NORTH CENTRAL ILLINOIS. UPPER AIR SUPPORT WITH THIS STORM AND A STRONG COLD CONVEYOR BELT WILL INCREASE MID LEVEL BAROCLINICITY AND INCREASE UPWARD VERTICAL MOTION OVER NORTHERN ILLINOIS AND NORTHWEST INDIANA. THIS CAN BE SEEN ON THE ISENTROPIC FORECASTS FOR 290 AND 300 K SURFACES. THE WARM AIR WHICH WILL WRAP AROUND THE EAST SIDE OF THE LOW WILL KEEP THE SNOW TO A MINIMUM OVER THE SOUTHERN PARTS OF THE FORECAST AREA OF NORTHERN ILLINOIS AND NORTHWEST INDIANA. WE WILL FORECAST THE HEAVIEST SNOW ALONG THE WISCONSIN BORDER. THE STRONG WIND AND SNOW IS EXPECTED TO CAUSE BLOWING SNOW. SO A BLIZZARD WARNING WAS ISSUED FOR EXTREME NORTHERN ILLINOIS. THE CENTER PART OF THE FORECAST AREA CAN EXPECT FREEZING RAIN...SLEET AND SNOW. THERE WILL BF FREEZING RAIN AND RAIN WILL IN THE SOUTH THIRD OF THE FORECAST AREA. WE WILL ISSUE A WINTER STORM ADVISORY FOR MOST OF NORTHEAST ILLINOIS. THIS WILL BE FOR FREEZING RAIN AND ICE PELLETS. A DRY SLOT MAY MOVE INTO EASTERN ILLINOIS AND NORTHWEST INDIANA BY SUNDAY MORNING. THE FORECAST SOUNDINGS SHOW FREEZING RAIN IN THE SOUTHERN PORTIONS OF THE CWA AND IN INDIANA. WE WILL FORECAST FREEZING RAIN FOR THOSE COUNTIES. ON SUNDAY NIGHT THE SURFACE LOW MOVES INTO NORTHERN ILLINOIS. WE EXPECT THE WIND TO DIMINISH LATE SUNDAY AFTERNOON. THEN COLD AIR IS EXPECTED TO MOVE IN AND THE PRECIPITATION WILL BECOME SNOW. ALONG THE WISCONSIN BORDER THIS STORM MAY PRODUCE UP TO EIGHT INCHES OF SNOW FOR A TOTAL SNOWFALL BY MONDAY MORNING. BY TUESDAY THE 500 MB CLOSED LOW WILL BE OVER MICHIGAN. THE PRECIPITATION WILL MOVE EAST BY THURSDAY THE HIGH TEMPERATURES WILL BE IN THE 40S. BY FRIDAY ANOTHER 500 MB TROUGH WAVE IS EXPECTED TO BE OVER MINNESOTA AND IOWA GIVING A CHANCE OF RAIN AND SNOW WEDNESDAY NIGHT AND THURSDAY. && .AVIATION... 650 AM CST MAJOR STORM SYSTEM CENTERED OVER THE CENTRAL PLAINS ALREADY MAKING IT PRESENCE KNOWN FAR AND WIDE. BIGGEST CONCERN FOR LOCAL AREA IN SHORTER TERM IS WINDS. EAST WINDS ALREADY GUSTING TO 30KTS IN CENTRAL AND NORTHWEST IL EARLY THIS MORNING AND CONTINUE TO INCREASE IN STRENGTH TODAY EVEN THOUGH LOW LEVEL INVERSION REMAINS IN PLACE. DEEPENING LOW PRESSURE IN KS AND STRONG HIGH PRESSURE RIDGE EXTENDING FROM HUDSON BAY SOUTHWARD TO THE SE U.S. WILL MAINTAIN TICHT PRESSURE GRADIENT ACROSS THE REGION. AS LOW APPROACHES THE LOWER MO VALLEY BY LATE AFTERNOON EXPECT GUSTS TO AROUND 35 KTS LOCALLY. AS THE VERY DYNAMIC SYSTEM MOVES INTO THE MID MS VALLEY TONIGHT THE BIG QUESTION FOR THE TERMINALS IS PRECIP TYPE AS SEVERAL FACTORS INVOLVED. THERE IS THE CONTINUED FEED OF VERY DRY LOW LEVEL AIR TO MAINTAIN EVAPORATIVE COOLING EVEN AFTER PRECIP BREAKS OUT LATE THIS AFTERNOON...THERE IS THE MASSIVE WARM AIR ADVECTION WITH MODELS SHOWING 60 TO 75 KT SE WINDS AT 850 MB BY 00Z SUN...THERE IS THE ADIABATIC COOLING RESULTING FROM THE STRONG ASCENT...AND THE RELEASE OF LATENT HEAT AS WATER VAPOR CONDENSES. FINE BALACE OF THESE FACTORS RESULTS IN WHERE SURFACE WILL REMAIN COLD ENOUGH AND WAA STRONG ENOUGH TO OVERCOME DYNAMIC COOLING TO KEEP FZRA AND PL GOING AND WHERE/WHEN COLUMN WILL BE COLD ENOUGH TO SUPPORT ONLY SN. HAVE BASICALLY FOLLOWED 00Z ENSEMBLE MEAN FORCAST AS GOOD COMPROMISE AT THIS POINT. THIS LEADS TO INITIAL OUTBREAK OF PCPN TO BE AS FZRA AND PL...CHANGING TO MAINLY RA THIS EVE FOR GYY AND MDW AS WAA PUNCHES NORTHWARD...BUT TURNING TO SN FOR RFD AND ORD AS MAX OF UVV EXPECTED TO BE ENOUGH TO COOL COLUMN. TRS && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...BLIZZARD WARNING 22 UTC TO 18 UTC SUNDAY WINNEBAGO...BOONE MCHENRY AND OGLE COUNTIES IN ILLIOIS WINTER STORM WARNING FROM LEE COUNTY TO COOK COUNTY AND FROM LAKE COUNTY IN ILLINOIS TO KANKAKEE COUNTY FROM 00 UTC TO 18 UTC SUNDAY. FREEZING RAIN ADVISORY 00 UTC TO 12 UTC SUNDAY LIVINGSTON IROQUOIS AND FORD COUNTIES IN ILLINOIS. .IN...FREEZING RAIN ADVISORY FOR LAKE PORTER JASPER NEWTON AND BENTON COUNTIES IN INDIANA FROM 00 UTC TO 18 UTC SUNDAY. .LM...GALE WRNG ALL LM AND NR SHORES TODAY THROUGH SUNDAY NIGHT. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
635 AM CST SAT FEB 24 2007 .UPDATE... 635 AM CST WE SAW THE OUTPUT FROM THE THE 06 UTC LOCALLY RUN WRF ARW MODEL WITH SOME ADVANCED PRECIPITATION PHYSICS. WE DECIDED TO UPDATE THE SNOW AMOUNTS AND TOTAL STORM ACCUMULATION FOR TONIGHT AND SUNDAY. && .DISCUSSION... 345 AM CST THIS IS A VERY DYNAMIC AND BAROCLINIC SURFACE CYCLONE DEVELOPING IN KANSAS. THERE IS STRONG WARM AIR ADVECTION EAST OF THE LOW WHICH IS IN WESTERN KANSAS. THUNDERSTORMS FROM OKLAHOMA TO WESTERN IOWA SHOW THE LARGE INSTABILITY. THE PROFILER WIND AT 300 MB AT 09 UTC SHOWS A 120 KNOT JET STREAK IN WEST CENTRAL TEXAS. WATER VAPOR LOOPS SHOW THE INTENSE CIRCULATION OVER SOUTHEAST COLORADO. WE EXPECT THIS SURFACE CYCLONE TO DEEPEN AND MOVE INTO SOUTHEAST IOWA BY 12 UTC SUNDAY. THE ACARS SOUNDING AT ORD SHOWS AN INVERSION AND THE STRONG WIND ABOVE 1400 FT FROM THE EAST. TAMDAR SOUNDING AT PIA AT 336 UTC SHOWS A DRY LAYER AROUND 900 MB. THIS DRY LAYER WAS UP TO 800 MB. AS THE LOW DEEPENS THE WIND WILL INCREASE DUE TO THE INCREASE IN THE PRESSURE GRADIENT. WE MAY HAVE WIND GUSTS TO 40 MPH IN NORTH CENTRAL ILLINOIS. UPPER AIR SUPPORT WITH THIS STORM AND A STRONG COLD CONVEYOR BELT WILL INCREASE MID LEVEL BAROCLINICITY AND INCREASE UPWARD VERTICAL MOTION OVER NORTHERN ILLINOIS AND NORTHWEST INDIANA. THIS CAN BE SEEN ON THE ISENTROPIC FORECASTS FOR 290 AND 300 K SURFACES. THE WARM AIR WHICH WILL WRAP AROUND THE EAST SIDE OF THE LOW WILL KEEP THE SNOW TO A MINIMUM OVER THE SOUTHERN PARTS OF THE FORECAST AREA OF NORTHERN ILLINOIS AND NORTHWEST INDIANA. WE WILL FORECAST THE HEAVIEST SNOW ALONG THE WISCONSIN BORDER. THE STRONG WIND AND SNOW IS EXPECTED TO CAUSE BLOWING SNOW. SO A BLIZZARD WARNING WAS ISSUED FOR EXTREME NORTHERN ILLINOIS. THE CENTER PART OF THE FORECAST AREA CAN EXPECT FREEZING RAIN...SLEET AND SNOW. THERE WILL BF FREEZING RAIN AND RAIN WILL IN THE SOUTH THIRD OF THE FORECAST AREA. WE WILL ISSUE A WINTER STORM ADVISORY FOR MOST OF NORTHEAST ILLINOIS. THIS WILL BE FOR FREEZING RAIN AND ICE PELLETS. A DRY SLOT MAY MOVE INTO EASTERN ILLINOIS AND NORTHWEST INDIANA BY SUNDAY MORNING. THE FORECAST SOUNDINGS SHOW FREEZING RAIN IN THE SOUTHERN PORTIONS OF THE CWA AND IN INDIANA. WE WILL FORECAST FREEZING RAIN FOR THOSE COUNTIES. ON SUNDAY NIGHT THE SURFACE LOW MOVES INTO NORTHERN ILLINOIS. WE EXPECT THE WIND TO DIMINISH LATE SUNDAY AFTERNOON. THEN COLD AIR IS EXPECTED TO MOVE IN AND THE PRECIPITATION WILL BECOME SNOW. ALONG THE WISCONSIN BORDER THIS STORM MAY PRODUCE UP TO EIGHT INCHES OF SNOW FOR A TOTAL SNOWFALL BY MONDAY MORNING. BY TUESDAY THE 500 MB CLOSED LOW WILL BE OVER MICHIGAN. THE PRECIPITATION WILL MOVE EAST BY THURSDAY THE HIGH TEMPERATURES WILL BE IN THE 40S. BY FRIDAY ANOTHER 500 MB TROUGH WAVE IS EXPECTED TO BE OVER MINNESOTA AND IOWA GIVING A CHANCE OF RAIN AND SNOW WEDNESDAY NIGHT AND THURSDAY. && .AVIATION... 1100 PM CST 06Z TAFS...BAND OF -SN PASSING JUST NORTH OF ORD ATTM...WITH NO RADAR ECHOES UPSTREAM ACROSS CENTRAL IL AND MO. WINDS HAVE TURNED A BIT MORE EASTERLY IN THE LAST FEW HRS...SO EXPECT MVFR CIGS COMING OFF LAKE MICHIGAN TO HOLD NORTH OF ORD THROUGH THE REST OF THE NIGHT. WINDS INCREASE SHARPLY TOMORROW OUT OF THE EAST AS LOW PRESSURE RAPIDLY DEEPENS OVR KS AND SFC HIGH REMAINS OVR ONTARIO. WARM AND VERY MOIST AIR ADVECTING NWD OVR THE COOL AND DRIER SFC LAYER LATE SAT AFTN SHOULD ALLOW SOME -FZDZ TO DEVELOP LATE SAT AFTN. FCST SOUNDINGS ARE INDICATING TEMPS RIGHT NEAR THE 0 DEG C ISOTHERM THROUGH SAT EVENING. THERE IS SOME QUESTION AS TO WHETHER THE STRENGTH OF LOW LEVEL WARM AIR SURGING NORTHWARD IN 75KT H8 JET WILL PUSH TEMP PROFILES ABV FREEZING. THUS...KEPT P-TYPE FZRA FOR THE CHICAGO AREA TERMINALS FROM 23Z THROUGH 06Z AND INDICATED A MIX OF FZRASNPL FOR RFD FOR THE SAME TIME FRAME. STRONGLY FORCED BAND INDICATED BY THE MODELS SHOULD CROSS THE AIRPORTS BTWN 03-06Z. THE DEEPER CONVECTION ASSOCIATED WITH THIS BAND SHOULD ALLOW MORE PL FOR A PERIOD AND PERHAPS MDT SN/PL AT RFD WHERE TEMPS WILL BE A FEW DEGREES COOLER. HANDEL && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...BLIZZARD WARNING 22 UTC TO 18 UTC SUNDAY WINNEBAGO...BOONE MCHENRY AND OGLE COUNTIES IN ILLIOIS WINTER STORM WARNING FROM LEE COUNTY TO COOK COUNTY AND FROM LAKE COUNTY IN ILLINOIS TO KANKAKEE COUNTY FROM 00 UTC TO 18 UTC SUNDAY. FREEZING RAIN ADVISORY 00 UTC TO 12 UTC SUNDAY LIVINGSTON IROQUOIS AND FORD COUNTIES IN ILLINOIS. .IN...FREEZING RAIN ADVISORY FOR LAKE PORTER JASPER NEWTON AND BENTON COUNTIES IN INDIANA FROM 00 UTC TO 18 UTC SUNDAY. .LM...GALE WRNG ALL LM AND NR SHORES TODAY THROUGH SUNDAY NIGHT. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
345 AM CST SAT FEB 24 2007 .DISCUSSION... 345 AM CST THIS IS A VERY DYNAMIC AND BAROCLINIC SURFACE CYCLONE DEVELOPING IN KANSAS. THERE IS STRONG WARM AIR ADVECTION EAST OF THE LOW WHICH IS IN WESTERN KANSAS. THUNDERSTORMS FROM OKLAHOMA TO WESTERN IOWA SHOW THE LARGE INSTABILITY. THE PROFILER WIND AT 300 MB AT 09 UTC SHOWS A 120 KNOT JET STREAK IN WEST CENTRAL TEXAS. WATER VAPOR LOOPS SHOW THE INTENSE CIRCULATION OVER SOUTHEAST COLORADO. WE EXPECT THIS SURFACE CYCLONE TO DEEPEN AND MOVE INTO SOUTHEAST IOWA BY 12 UTC SUNDAY. THE ACARS SOUNDING AT ORD SHOWS AN INVERSION AND THE STRONG WIND ABOVE 1400 FT FROM THE EAST. TAMDAR SOUNDING AT PIA AT 336 UTC SHOWS A DRY LAYER AROUND 900 MB. THIS DRY LAYER WAS UP TO 800 MB. AS THE LOW DEEPENS THE WIND WILL INCREASE DUE TO THE INCREASE IN THE PRESSURE GRADIENT. WE MAY HAVE WIND GUSTS TO 40 MPH IN NORTH CENTRAL ILLINOIS. UPPER AIR SUPPORT WITH THIS STORM AND A STRONG COLD CONVEYOR BELT WILL INCREASE MID LEVEL BAROCLINICITY AND INCREASE UPWARD VERTICAL MOTION OVER NORTHERN ILLINOIS AND NORTHWEST INDIANA. THIS CAN BE SEEN ON THE ISENTROPIC FORECASTS FOR 290 AND 300 K SURFACES. THE WARM AIR WHICH WILL WRAP AROUND THE EAST SIDE OF THE LOW WILL KEEP THE SNOW TO A MINIMUM OVER THE SOUTHERN PARTS OF THE FORECAST AREA OF NORTHERN ILLINOIS AND NORTHWEST INDIANA. WE WILL FORECAST THE HEAVIEST SNOW ALONG THE WISCONSIN BORDER. THE STRONG WIND AND SNOW IS EXPECTED TO CAUSE BLOWING SNOW. SO A BLIZZARD WARNING WAS ISSUED FOR EXTREME NORTHERN ILLINOIS. THE CENTER PART OF THE FORECAST AREA CAN EXPECT FREEZING RAIN...SLEET AND SNOW. THERE WILL BF FREEZING RAIN AND RAIN WILL IN THE SOUTH THIRD OF THE FORECAST AREA. WE WILL ISSUE A WINTER STORM ADVISORY FOR MOST OF NORTHEAST ILLINOIS. THIS WILL BE FOR FREEZING RAIN AND ICE PELLETS. A DRY SLOT MAY MOVE INTO EASTERN ILLINOIS AND NORTHWEST INDIANA BY SUNDAY MORNING. THE FORECAST SOUNDINGS SHOW FREEZING RAIN IN THE SOUTHERN PORTIONS OF THE CWA AND IN INDIANA. WE WILL FORECAST FREEZING RAIN FOR THOSE COUNTIES. ON SUNDAY NIGHT THE SURFACE LOW MOVES INTO NORTHERN ILLINOIS. WE EXPECT THE WIND TO DIMINISH LATE SUNDAY AFTERNOON. THEN COLD AIR IS EXPECTED TO MOVE IN AND THE PRECIPITATION WILL BECOME SNOW. ALONG THE WISCONSIN BORDER THIS STORM MAY PRODUCE UP TO EIGHT INCHES OF SNOW FOR A TOTAL SNOWFALL BY MONDAY MORNING. BY TUESDAY THE 500 MB CLOSED LOW WILL BE OVER MICHIGAN. THE PRECIPITATION WILL MOVE EAST BY THURSDAY THE HIGH TEMPERATURES WILL BE IN THE 40S. BY FRIDAY ANOTHER 500 MB TROUGH WAVE IS EXPECTED TO BE OVER MINNESOTA AND IOWA GIVING A CHANCE OF RAIN AND SNOW WEDNESDAY NIGHT AND THURSDAY. && .AVIATION... 1100 PM CST 06Z TAFS...BAND OF -SN PASSING JUST NORTH OF ORD ATTM...WITH NO RADAR ECHOES UPSTREAM ACROSS CENTRAL IL AND MO. WINDS HAVE TURNED A BIT MORE EASTERLY IN THE LAST FEW HRS...SO EXPECT MVFR CIGS COMING OFF LAKE MICHIGAN TO HOLD NORTH OF ORD THROUGH THE REST OF THE NIGHT. WINDS INCREASE SHARPLY TOMORROW OUT OF THE EAST AS LOW PRESSURE RAPIDLY DEEPENS OVR KS AND SFC HIGH REMAINS OVR ONTARIO. WARM AND VERY MOIST AIR ADVECTING NWD OVR THE COOL AND DRIER SFC LAYER LATE SAT AFTN SHOULD ALLOW SOME -FZDZ TO DEVELOP LATE SAT AFTN. FCST SOUNDINGS ARE INDICATING TEMPS RIGHT NEAR THE 0 DEG C ISOTHERM THROUGH SAT EVENING. THERE IS SOME QUESTION AS TO WHETHER THE STRENGTH OF LOW LEVEL WARM AIR SURGING NORTHWARD IN 75KT H8 JET WILL PUSH TEMP PROFILES ABV FREEZING. THUS...KEPT P-TYPE FZRA FOR THE CHICAGO AREA TERMINALS FROM 23Z THROUGH 06Z AND INDICATED A MIX OF FZRASNPL FOR RFD FOR THE SAME TIME FRAME. STRONGLY FORCED BAND INDICATED BY THE MODELS SHOULD CROSS THE AIRPORTS BTWN 03-06Z. THE DEEPER CONVECTION ASSOCIATED WITH THIS BAND SHOULD ALLOW MORE PL FOR A PERIOD AND PERHAPS MDT SN/PL AT RFD WHERE TEMPS WILL BE A FEW DEGREES COOLER. HANDEL && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...BLIZZARD WARNING 22 UTC TO 18 UTC SUNDAY WINNEBAGO...BOONE MCHENRY AND OGLE COUNTIES IN ILLIOIS WINTER STORM WARNING FROM LEE COUNTY TO COOK COUNTY AND FROM LAKE COUNTY IN ILLINOIS TO KANKAKEE COUNTY FROM 00 UTC TO 18 UTC SUNDAY. FREEZING RAIN ADVISORY 00 UTC TO 12 UTC SUNDAY LIVINGSTON IROQUOIS AND FORD COUNTIES IN ILLINOIS. .IN...FREEZING RAIN ADVISORY FOR LAKE PORTER JASPER NEWTON AND BENTON COUNTIES IN INDIANA FROM 00 UTC TO 18 UTC SUNDAY. .LM...GALE WRNG ALL LM AND NR SHORES TODAY THROUGH SUNDAY NIGHT. && $$
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
741 AM EST SAT FEB 24 2007 .UPDATE... SENT AN UPDATE TO THE ZONES TO MENTION LIGHT SNOW LIKELY FROM MUSKEGON SOUTH DOWN THE LAKE SHORE TO SOUTH HAVEN AND EXTENDING INLAND TO PLAINWELL AND KALAMAZOO. REPORTS FROM BLOOMINGDALE AND KALAMAZOO THIS MORNING INDICATE THAT AROUND AN INCH OF SNOW HAS FALLEN. THE LIGHT SNOW IS ASSOCIATED WITH ISENTROPIC LIFT...WHICH WILL BE FADING THROUGH THE COURSE OF THE MORNING. NOT EXPECTING MUCH MORE IN THE WAY OF ACCUMULATION...BUT ANOTHER HALF INCH TO AN INCH IS POSSIBLE BEFORE IT TAPERS OFF BY MIDDAY. .PREV DISCUSSION...ISSUED AT 312 AM SHORT TERM... SKIES ARE MO CLOUDY ATTM. REGIONAL RADARS SHOWS A LARGE ARC OF SNOW STRETCHING ACROSS SOUTHERN WISCONSIN. THIS SNOW IS CONVECTIVE IN NATURE AS LIGHTNING HAS BEEN EMBEDDED WITH IT MUCH OF THE NIGHT. KGRR-88D SHOWS SNOW ALOFT TRYING TO MOVE INTO THE SOUTHWEST CWA. TAMDAR SOUNDINGS FROM A CHI-MKG LINE SHOW VERY DRY AIR IN PLACE AND THIS PCPN WILL HAVE DIFFICULTY MAKING INTO THE CWA. NONETHELESS...BEH JUST DROPPED TO 5SM -SN. SFC ANALYSIS SHOWS LOW PRESSURE IN COLORADO. CONVECTION STRETCHES FROM THE RED RIVER TO THE RED RIVER OF THE NORTH. THIS CONTINUES TO BE A DYNAMIC SYSTEM AND IS THE FOCUS OF THE SHORT TERM. GFS/NAM CONTINUE TO SHOW THE LOW MOVING ENE THROUGH KANSAS BEFORE TURNING NORTHEAST AND MOVING TOWARD THE SOUTHERN CWA LATE SUNDAY. THE GULF IS WIDE OPEN IN FRONT OF IT AND WILL SUPPLY AN AMPLE SOURCE OF MOISTURE. THERE IS A LARGE AREA OF PCPN ATTM STRETCHING FROM WISCONSIN SOUTHEAST TO SOUTHERN LAKE MICHIGAN. THIS PCPN IS BEING GENERATED BY STRONG ISENTROPIC LIFT. CONDENSATION PRESSURE DEFICITS FALL TO NEAR 0MB THIS MORNING OVER THE WESTERN CWA. WILL ADD A CHC OF SNOW TO THE SOUTHWEST CWA THIS MORNING. THE GFS ENSEMBLES ARE IN CLOSE AGREEMENT ON THE TRACK OF THE LOW AND LINE UP WITH THE NAM TOO. THOSE SOLUTIONS TAKE THE LOW ACROSS SBN TO DTW. THAT WOULD PLACE THE HEAVIEST SNOW ACROSS THE NORTHERN CWA. FCST SOUNDINGS SHOW THE POTENTIAL FOR SOME IP TO DEVELOP OVER THE SOUTHERN CWA AS THE NOSE OF WARM AIR NEAR 800 MB TOUCHES THE 0C MARK. LATEST 20KM WRF AND GLBL GEM ARE SIMILAR TO THE GFS IN BRINGING PCPN INTO THE SOUTHWEST CWA THIS EVENING AND COVERING MUCH OF THE CWA BY 06Z. WITH THAT IN MIND WILL BUMP UP THE START TIME OF THE WINTER STORM WATCH OVER THE NORTHERN 2/3 OF THE CWA TO MATCH THE SOUTHERN CWA...06Z. THE NAM SEEMS A BIT WET GIVEN THE WEAKENING NATURE OF THE SYSTEM. BUT THERE ARE SOME STRONG DYNAMICS IN THE FORM OF 850-500 MB FGEN FORCING TO KEEP THE SYSTEM GOING. ONE THING THAT STILL IS TROUBLING IS THAT THE TIP OF THE DRY SLOT IS STILL PROGD TO MOVE THROUGH THE CWA LATE SUNDAY MORNING AND EARLY AFTERNOON WITH DEEPER MOISTURE MOVING BACK IN LATE SUNDAY AND SUNDAY NIGHT. THUS...THERE LOOKS TO BE TWO PERIODS OF PCPN WITH A LULL IN BETWEEN. GFS SNOW AMOUNTS LOOK GOOD WITH TOTALS FROM THIS EVENING THROUGH SUNDAY EVENING 6-8 INCHES...AND THEN ANOTHER 2 TO 4 SUNDAY NIGHT. THE UPPER LOW REMAINS OVER LOWER MICHIGAN THROUGH MONDAY. SO THIS COULD BE A PROLONGED SNOW EVENT. WINDS WILL STILL BE A FACTOR. BUFKIT WIND PROFILE SHOWS 40 KT WINDS AROUND 1K FEET AT 12Z SUNDAY. I DON/T THINK WE/LL BE ABLE TO TAP ALL OF THAT AT THAT TIME OF DAY BUT GUSTY WINDS WILL CREATE A HAZARD. WOULDN/T BE SURPRISED TO SEE VISIBILITIES DROP TO A HALF MILE AT TIMES. WITH THE UPPER LOW IN PLACE...MORE SNOW IS EXPECTED MONDAY. QPF AROUND A TENTH OF AN INCH WOULD SUGGEST ANOTHER 1-3 INCHES. .LONG TERM... NO CHANGES MADE IN THE EXTENDED PORTION OF THE FORECAST (FROM MONDAY NIGHT THROUGH THE END OF THE WORK WEEK). STACKED LOW WILL STILL BE SITUATED OVER THE AREA MONDAY NIGHT...BUT IT WILL HAVE WEAKENED SUBSTANTIALLY BY THIS POINT. USED THE GFS FOR GUIDANCE. GIVEN ITS SOLUTION...THE SURFACE LOW WILL HAVE RISEN TO 1003MB/S BY MONDAY EVENING. IT CONTINUES TO WEAKEN AND SLIDE EAST WITH TIME INTO TUESDAY. MAINTAINED THE CHANCES FOR LIGHT SNOW BOTH MONDAY NIGHT AND TUESDAY AS THERE SHOULD BE SOME LINGERING LIGHT SNOW...JUST NOT EXPECTING A WHOLE LOT OF ACCUMULATION IN THIS TIME FRAME. TUESDAY NIGHT SHOULD BE A COLD NIGHT GIVEN SURFACE RIDGING IN PLACE AND A FRESH SNOWPACK. THE MIDDLE OF THE WEEK WILL SEE A SHORT RESPITE TO THE WX...BEFORE OUR NEXT SYSTEM APPROACHES FROM THE WEST WEDNESDAY NIGHT. WE MAY NEED TO ADD PRECIPITATION TO THE FORECAST WEDNESDAY NIGHT WITH STRONG WARM AIR ADVECTION ONGOING. THURSDAY AND THURSDAY NIGHT MAY BE TRENDING MORE TOWARD RAIN AS WELL...AS 850MB TEMPS RISE TO AROUND +6 C. COLDER AIR SWEEPS IN BEHIND A FRONTAL PASSAGE ON FRIDAY. $$ && .GRR WATCHES/WARNINGS/ADVISORIES...WINTER STORM WATCH FOR THE ENTIRE CWA FROM 1 AM SUNDAY THROUGH 7 AM MONDAY. && $$ 93 DUKE
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
114 PM PST SAT FEB 24 2007 .SYNOPSIS... HIGH PRESSURE OVER THE AREA TODAY WILL GIVE WAY TO DEVELOPING LOW PRESSURE ON SUNDAY. INCREASING ONSHORE FLOW WILL BRING COOLING... GUSTY WINDS IN THE MOUNTAINS AND DESERTS...AND AN INCREASE IN CLOUDINESS ALONG AND WEST OF THE MOUNTAINS. THERE IS ALSO A CHANCE FOR SOME LIGHT PRECIPITATION TO BREAK OUT AT TIMES ON THE COASTAL SLOPES BEGINNING SUNDAY NIGHT AND CONTINUING THROUGH TUESDAY. SOME PATCHY DRIZZLE WILL BE POSSIBLE AT TIMES WEST OF THE MOUNTAINS AS WELL...WITH THE BEST CHANCE FOR MEASURABLE LIGHT RAIN COMING ON TUESDAY AS A TROUGH OF LOW PRESSURE SWINGS THROUGH THE REGION. THEN BREEZY AT TIMES AND AND CONTINUED COOL THROUGH FRIDAY. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... SUNSHINE AND LIGHT WINDS MADE FOR A PLEASANT DAY ACROSS THE SOUTHLAND...EVEN THOUGH MAX TEMPERATURES WERE STILL RUNNING A BIT BELOW AVERAGE. SURFACE PRESSURE GRADIENTS WERE WEAK AND THE AIR FAIRLY DRY WITH DEWPOINTS IN THE 20S AND 30S IN MOST AREAS WEST OF THE MOUNTAINS. SUNDAY SHOULD STILL BE A DECENT DAY...BUT THE WEATHER WILL DETERIORATE GRADUALLY AS THE WEST WINDS INCREASE AND THE MARINE LAYER RETURNS. SURFACE HIGH PRESSURE OVER THE AREA TODAY WILL WEAKEN OVERNIGHT AND SUN AS WEAK HIGH PRESSURE ALOFT GIVES WAY TO INCREASING NW FLOW ALOFT. DEVELOPING LOW PRESSURE OVER THE GREAT BASIN WILL BRING A RETURN OF BRISK ONSHORE FLOW TO SOUTHWEST CALIFORNIA AND A DEEP MARINE LAYER BEGINNING ON SUN AFTERNOON. THE MOIST WESTERLY FLOW WILL BRING FOG...AND POSSIBLY LIGHT PRECIPITATION TO THE COASTAL SLOPES...WITH PATCHY DRIZZLE POSSIBLE WEST OF THE MOUNTAINS AS WELL BEGINNING SUNDAY NIGHT. THE WIND WILL BE STRONG AND GUSTY IN THE MOUNTAINS AND DESERTS...AND COULD INCREASE TO NEAR ADVISORY STRENGTH ON SUNDAY. THE ONSHORE FLOW AND ADDITIONAL MARINE CLOUDS WILL KEEP DAYTIME TEMPERATURES SEVERAL DEGREES BELOW AVERAGE. A LONG-WAVE TROUGH IS FORECAST TO SWING THROUGH THE REGION ON TUE. ALL THE MAJOR MODELS ARE SIMILAR WITH THE INTENSITY AND TIMING...SO IT LOOKS LIKE OUR BEST CHANCE FOR SOME MORE WIDESPREAD MEASURABLE PRECIPITATION WOULD BE ON TUE. SOME SNOW WILL BE POSSIBLE IN THE MOUNTAINS AS THE FREEZING LEVEL FALLS BELOW 5K FT TUE NIGHT AND WED. IF THE PRECIP MATERIALIZES...EARLY INDICATIONS ARE MOST AREAS WOULD RECEIVE LESS THAN ONE-HALF INCH...EXCEPT THE COASTAL SLOPES WHICH WOULD GET ENHANCEMENT FROM THE STRONG UPSLOPE FLOW. SOME LIGHT RAIN AND SNOW COULD LINGER INTO WED...DEPENDING ON THE SPEED OF THE TROUGH. COOL AND BREEZY CONDITIONS ARE LIKELY TO LINGER INTO THU...FOLLOWED BY WEAK OFFSHORE FLOW...CLEAR SKIES...AND SOME MINOR WARMING FOR FRI AND SAT. && .AVIATION... 241930Z...WEAK OFFSHORE FLOW CONTINUES BUT IS TRENDING ONSHORE AND IS EXPECTED TO BECOME ONSHORE THIS AFTERNOON. LATE MORNING ACARS SOUNDINGS INDICATE THE MARINE LAYER REMAINS DISRUPTED. EXPECT SOME RECOVERY TO BEGIN THIS EVENING AS THE ONSHORE FLOW RETURNS. MORE SIGNIFICANT DEEPENING OF THE MARINE LAYER IS EXPECTED SUNDAY AFTERNOON WITH THE DEPTH TO 4000 FEET OR DEEPER EXPECTED SUNDAY NIGHT. A MOSTLY CLEAR SKY IS EXPECTED ALL AREAS THROUGH THIS EVENING. SOME STRATUS/FOG COULD FORM ALONG THE COAST AFTER MIDNIGHT AND SOME RADIATIONAL FOG IS POSSIBLE AROUND KCNO BEFORE SUNRISE ON SUNDAY. KSAN...KCRQ AND KSNA...NO SIGNIFICANT WEATHER ISSUES THROUGH THIS EVENING. STRATUS COULD MOVE OVER THE AIRPORTS AFTER MIDNIGHT. BASES SHOULD BE AROUND 800 TO 1000 FEET MSL WITH TOPS TO 1200 FEET MSL. KONT...NO SIGNIFICANT WEATHER ISSUES THROUGH THIS EVENING. PATCHY FOG IS POSSIBLE VICINITY OF THE AIRPORT BEFORE SUNRISE ON SUNDAY WHICH COULD MOVE OVER THE AIRPORT FROM TIME TO TIME. ANY FOG SHOULD DISSIPATE WITHIN AN HOUR OR TWO AFTER SUNRISE. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...JAD AVIATION/MARINE...HORTON NWS ON THE WEB AT WEATHER.GOV/SANDIEGO
AREA FORECAST DISCUSSION...COR FOR HEADLINES
NWS CHICAGO/ROMEOVILLE IL
230 PM CST SAT FEB 24 2007 .DISCUSSION AFTERNOON FORECAST STRONG RAPIDLY OCCLUDING LOW OVER CENTRAL KANSAS DESTINED TO MOVE TOWARD NRN ILL LATER SUN AND MON BUT BE FILLING OVER TIME. INITIAL CONCERN HOWEVER IS APPROACHING BAND OF RAIN THROUGH CENTRAL ILL. SFC TEMPS ACROSS FCST AREA HAVE INCHED TOWARD 30-32F TODAY BUT HAVE STRONG CONCERNS ABOUT CONTINUING FEED OF DRY AIR FROM EAST. ONCE PRECIP FALLS INTO THIS ZONE THE WET BULB TEMP WILL BE REACHED WHICH IS WELL BELOW 32F. THUS ANY PROGRESS IN WARMING TODAY WILL BE OFFSET BY EVAP COOLING MUCH LESS DARKNESS. FOCUS OF APPROACHING PRECIP AREA APPEARS TO BE SINKING TOWARD THE OHIO VALLEY BUT MODELS SUGGEST VERY STRONG WARMING ALOFT WITH MARKED VEERING SIGNATURE IN MODEL AND ACARS WIND FIELDS. THIS SHOULD FORCE A PERIOD OF STEADY POTENTIALLY MODERATE RAIN FOR A FEW HOURS THIS EVENING BEFORE AREA IS OVER RUN BY A DEVELOPING DRY SLOT /ALOFT/ FROM SW. TIMIMG STILL ON TRACK FOR MAIN EVENT BETWEEN 00Z AND 06Z THIS EVENING. SOME MIX OF PRECIP IS LKLY MAINLY SLEET OVER SRN AND CENTRAL FCST AREA WITH SNOW AND SLEET FURTHER N ALONG THE WISCONSIN BORDER. ANY SNOW AMOUNTS WILL BE HELD DOWN BY PRECIP MIX. WITH LOW TRACKING OVERHEAD LATER SUN AND MON AIRMASS WITH COOL AND LINGERING PRECIP WILL BE TURNED TO SNOW. CANT RULE OUT AREAS OF LIGHT SNOW ACCUMULATION MAINLY SUNDAY NIGHT AND MONDAY AS UNDERMINED IMPULSES PIVOT AROUND DECAYING SYSTEM. IT WILL BE MID WEEK BEFORE SUSTAINED CLEARING OCCURS. UPPER AIR PATTERN SHOWS THE APPROACHING LOW RUNNING HEAD LONG INTO A TEMPORARY BLOCKING PATTERN WHICH ACCOUNTS FOR THE SLUGGISH RETREAT. HOWEVER THIS SITUATION WONT LAST LONG AND ANOTHER SIMILAR HIGH AMPLITUDE TROUGH FCST TO SWING THROUGH THE AREA ABOUT THUR-FRI. THIS TIME NO ICE. NEXT 12HRS WILL BE CRITICAL FOR FORECAST AREA. GIVEN EXPECTATION OF SUBFREEZING SFC TEMPS THROUGH AT LEAST THE FIST PART OF THE NIGHT AND POTENTIAL INTENSITY OF RAIN THE COURSE OF LEAST REGRET DICTATES AN ICE STORM WARNING FOR THE CENTRAL 2/3 OF FCST AREA WITH A WINTER STORM WARNING ALONG THE WISC BORDER...MAINLY FOR SNOW AND SLEET SOME FRZG RAIN. SOUTHERN THIRD OF AREA WILL CONTINUE A FREEZING RAIN ADVISORY. ALL ARE 6PM THIS EVENING TO 6AM SUNDAY. EXPECT MOST INTENSE PRECIPITATION DURING FIRST 6HRS THIS EVENING. DRYING ALOFT LATER IN THE NIGHT MAY REDUCE PRECIP TO DRIZZLE. THRESHOLD FOR ICE STORM IS QUARTER INCH OF ICE AND WITH EXPECTED INTENSITY OF RAIN THIS LEVEL MAY BE REACHED IN MANY SPOTS. TEMPS COULD STRUGGLE ABOVE FREEZING LATER TONIGHT IN WARNING AREA...AND LIKELY BE IN LOW TO MID 30S ON BY SUNDAY AFTERNOON. THIS IS ONE OF THE MORE CHALLENGING FCST SITUATIONS OF RECENT MEMORY. KML && .AVIATION... 650 AM CST MAJOR STORM SYSTEM CENTERED OVER THE CENTRAL PLAINS ALREADY MAKING IT PRESENCE KNOWN FAR AND WIDE. BIGGEST CONCERN FOR LOCAL AREA IN SHORTER TERM IS WINDS. EAST WINDS ALREADY GUSTING TO 30KTS IN CENTRAL AND NORTHWEST IL EARLY THIS MORNING AND CONTINUE TO INCREASE IN STRENGTH TODAY EVEN THOUGH LOW LEVEL INVERSION REMAINS IN PLACE. DEEPENING LOW PRESSURE IN KS AND STRONG HIGH PRESSURE RIDGE EXTENDING FROM HUDSON BAY SOUTHWARD TO THE SE U.S. WILL MAINTAIN TICHT PRESSURE GRADIENT ACROSS THE REGION. AS LOW APPROACHES THE LOWER MO VALLEY BY LATE AFTERNOON EXPECT GUSTS TO AROUND 35 KTS LOCALLY. AS THE VERY DYNAMIC SYSTEM MOVES INTO THE MID MS VALLEY TONIGHT THE BIG QUESTION FOR THE TERMINALS IS PRECIP TYPE AS SEVERAL FACTORS INVOLVED. THERE IS THE CONTINUED FEED OF VERY DRY LOW LEVEL AIR TO MAINTAIN EVAPORATIVE COOLING EVEN AFTER PRECIP BREAKS OUT LATE THIS AFTERNOON...THERE IS THE MASSIVE WARM AIR ADVECTION WITH MODELS SHOWING 60 TO 75 KT SE WINDS AT 850 MB BY 00Z SUN...THERE IS THE ADIABATIC COOLING RESULTING FROM THE STRONG ASCENT...AND THE RELEASE OF LATENT HEAT AS WATER VAPOR CONDENSES. FINE BALACE OF THESE FACTORS RESULTS IN WHERE SURFACE WILL REMAIN COLD ENOUGH AND WAA STRONG ENOUGH TO OVERCOME DYNAMIC COOLING TO KEEP FZRA AND PL GOING AND WHERE/WHEN COLUMN WILL BE COLD ENOUGH TO SUPPORT ONLY SN. HAVE BASICALLY FOLLOWED 00Z ENSEMBLE MEAN FORCAST AS GOOD COMPROMISE AT THIS POINT. THIS LEADS TO INITIAL OUTBREAK OF PCPN TO BE AS FZRA AND PL...CHANGING TO MAINLY RA THIS EVE FOR GYY AND MDW AS WAA PUNCHES NORTHWARD...BUT TURNING TO SN FOR RFD AND ORD AS MAX OF UVV EXPECTED TO BE ENOUGH TO COOL COLUMN. TRS && .LOT WATCHES/WARNINGS/ADVISORIES... .IL...WINTER STORM WARNING 6PM SAT TO 6AM SUN FOR WISC BORDER COUNTIES ICE STORM WARNING 6PM TO 6AM OGLE TO COOK COUNTY SOUTH TO LASALLE TO KANKAKEE COUNTY FREEZING RAIN ADVISORY 00 UTC TO 12 UTC SUNDAY LIVINGSTON IROQUOIS AND FORD COUNTIES IN ILLINOIS. .IN...ICE STORM WARNING LAKE PORTER NEWTON AND JASPER CO 00Z TO 12Z. FREEZING RAIN ADVISORY BENTON COUNTY FROM 00 UTC TO 12 UTC SUNDAY. .LM...GALE WRNG ALL LM AND NR SHORES TODAY THROUGH SUNDAY NIGHT. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
357 PM EST SAT FEB 24 2007 .DISCUSSION... TAKING A LOOK AT CURRENT CONDITIONS...HIGH PRESSURE RULES...AT LEAST THE NORTHEASTERN TWO THIRDS OF THE REGION. THE CENTER OF HIGH PRESSURE IS WELL TO OUR NORTHEAST...WITH ITS CORE OVER HUDSON BAY. THIS HIGH WILL NOT BUDGE MUCH OVER THE NEXT SEVERAL DAYS...HELPING TO KEEP THE EXTREME EASTERN PORTIONS OF THE CWA CLOUD FREE...AND DRYING UP THE LOWER LEVELS OF THE ATMOSPHERE...SLOWING DOWN THE ONSET OF SNOW FROM THE SOUTHWEST. LOOKING TO OUR SOUTHWEST...A SLOWLY WEAKENING LOW OVER EASTERN KANSAS IS POISED TO HEAD INTO THE GREAT LAKES REGION...BRINGING ITS MIXED BAG OF PRECIPITATION TOWARDS THE AREA. FREEZING RAIN WAS BEING REPORTED AS FAR NORTH AS SOUTHEASTERN MINNESOTA AND WEST CENTRAL WISCONSIN...AS TEMPERATURES HOVER RIGHT AROUND THE FREEZING MARK. WITH PLENTY OF GULF MOISTURE TO WORK WITH...THUNDERSTORMS WERE COMMON FROM LOUISIANA UP THROUGH EASTERN MISSOURI...AND THEN BACK INTO KANSAS AROUND THE SURFACE LOW...OUT AHEAD OF THE 115KT 250MB JET ACROSS NORTHERN TEXAS AND WESTERN ARKANSAS. MAIN FCST CONCERNS ARE HANDLING OF POTENT SHRTWV SET TO LIFT NE FM THE SRN PLAINS AND SN TIMING/AMTS/HEADLINES. PER NCEP PREFERENCE... GENERALLY FOLLOWED THE GFS THRU F36...THEN A BLEND OF GFS/NAM AFT F36 FOR EVOLVING LO PRES SYS. FOR TNGT...125KT H3 JET MAX ROUNDING UPR LO OVER THE SRN ROCKIES FCST TO LIFT NEWD AND DRAG OCCLUDING LO TO THE MO/IA BORDER BY 12Z SUN...FARTHER N THAN FCST BY PREVIOUS GUIDANCE BUT NOT UNRSNBL CONSIDERING THE HEFTY DYNAMICS THAT CAUSED 00Z-12Z H3 HGT FALLS UP TO 200M AT AMA LAST NGT. NAM IS EVEN FARTHER N WITH THE CENTER OF LOWEST HGTS/PRES (INTO CNTRL IA)...BUT WL FOLLOW MORE CONSISTENT GFS FOR NOW. THE AREA OF UPR DVGC TO THE N OF THE UPR JET ROUNDING THE E SIDE OF THE LO FCST TO LIFT N INTO THE FA AFT MIDNGT. QUESTION REMAINS HOW QUICKLY/EFFECTIVELY ACCOMPANYING UVV CAN SATURATE THE BONE DRY LO-MID LVLS SHOWN ON THE 12Z APX RAOB/ 15Z TAMDAR SDNG FM TVC THAT IS REPRESENTATIVE OF AIRMASS OVER THE FA. GIVEN THE SHARP GRADIENT OF MSTR BTWN GRB/APX AT 12Z...EXPECT A VERY SHARP GRADIENT BTWN MODERATE SN AND LTL IF ANY SN. LLVL FLOW FCST TO REMAIN E TNGT...MAXIMIZING DRY ADVCTN. EXPECT A MAINLY DRY EVNG...BUT WL THEN INCRS POPS OVERNGT NEAR THE WI BORDER WITH ARRIVAL OF UPR DVGC. ADJUSTED FOR SLOWLY FALLING TO STEADY TEMPERATURES...MAINLY ACROSS THE WESTERN HALF OF THE CWA THROUGH MIDNIGHT TONIGHT...GIVEN GOOD MIXING IN THE LOWER LEVELS AND CLOUD COVER. AS FOR SUNDAY NIGHT...WENT SLIGHTLY COOLER WEST AND WARMER EAST FOR HIGH TEMPERATURES GIVEN THE FACT THAT CLOUDS WILL STILL HAVE A TOUGH TIME GETTING INTO THE EASTERN MOST COUNTIES OF THE CWA. NAM/GFS IN GOOD AGREEMENT SHOWING QPF BULLSEYE ARND 0.50 INCH S OF IMT-ESC TO MNM BTWN 12Z-18Z SUN UNDER AREA OF SHARPER H4-2 DVGC IN LEFT EXIT OF UPR JET LIFTING INTO THE LWR GRT LKS INTERACTS WITH SHARPER ISENTROPIC LIFT ON THE 280-300K SFC (H85-6)/ESE H85 WINDS TO 50KT/AXIS OF HIER SPECIFIC HUMIDITY (ABOUT 3 G/KG AT H7-75)/SHARPER H85-7 FGEN AND WHERE E LLVL FLOW OFFERS POTENTIAL FOR LK ENHANCEMENT OFF NRN LK MI. 280-290KISENTROPIC LIFT/MSTR TO THE NE IS QUITE A BIT WEAKER/ LESS...SO EXPECT A SHARP TRANSITION TO JUST THICKENING MID CLD ASSOCIATED WITH THE BETTER LIFT PRESENT THERE ON THE 300K SFC. THE BETTER ISENTROPIC LIFT/UPR DVGC/FGEN IS FCST TO DRIFT TO THE NE IN THE AFTN INTO THE DRIER AIR...SO THE HVY SN IN THE MRNG OVER THE SCNTRL MAY DIMINISH A BIT IN THE AFTN. TENDED TO SHARPEN THE NRN EDGE OF THE HIER QPF VS WHAT WAS FCST BY GUIDANCE TO ACCOUNT FOR TENACIOUS DRY AIR ASSOCIATED WITH SLOWLY BACKING LLVL FLOW AND MODEL TENDENCY TO SMOOTH QPF TOO FAR INTO THE DRIER AIR. ON SUN NGT/MON...GFS/NAM INDICATE OCCLUDED LO DRIFTING SLOWLY E... WITH FA IN GENERAL UPR DVGC TO THE N OF CLOSED LO CENTER. BEST H85-5 QVECTOR CNVGC REMAINS OVER THE SCNTRL ZNS. ALTHOUGH THERE IS A SLOW BACKING TREND TO THE LLVL WINDS...FLOW REMAINS FVRBL FOR A CONTINUED LONG FETCH ACRS NRN LK MI AND PERSISTENT WEAK LK ENHANCEMENT... MAINLY S OF HIGHWAY 2. BUT CONSIDERING THE LACK OF SHARP PERSISTENT FGEN AND APPRECIABLE JET DYNAMICS/SHARPER UPR DVGC...AND TENDENCY FOR SLOWLY BACKING LLVL FLOW TO ADVECT LLVL DRY AIR INTO THE FA AND WEAKEN THE OCCLUSION TO THE S...THINK SN INTENSITY WL BE LESS THAN EARLY ON SUN. BEST CHC FOR ADDITIONAL HEAVIER SN WL BE OVER THE FAR SCNTRL WHERE THERE IS POTENTIAL FOR LK ENHANCEMENT/UPSLOPING. SLOWED THE EXIT OF WEATHER DOWN SLIGHTLY...ADDING FLURRIES BEHIND THE DEPARTING SYSTEM...FOR TUESDAY...WITH THE EXITING 500MB LOW STILL STUCK NEAR CHICAGO AND NORTHERN INDIANA. UPGRADED GOING WATCH TO WRNG FOR DELTA/DICKINSON/MNM COUNTIES FOR SUN THRU MON EVEN THOUGH SN INTENSITY AT MOST PLACES WL TEND TO DIMINISH SUN NGT/MON. SINCE BEST DYNAMICS ON SUN WL MISS IRON COUNTY TO THE E AND THERE IS LESS CHC FOR APPRECIABLE LK ENHANCEMENT THERE...OPTED TO ISSUE ONLY ADVY FOR THAT COUNTY. IN THE MEDIUM/EXTENDED RANGE...EXPECT HI PRES RDG TO BRING RELATIVELY TRANQUIL WX TUE NGT THRU WED BEFORE LO PRES E OF DEEPENING TROF IN THE ROCKIES EJECTS TO THE NE. OPERATIONAL GUIDANCE HAS COME INTO BETTER AGREEMENT SHOWING LO TRACKING TO THE W OF THE CWA INTO MN BY LATE THU AND THEN INTO ONTARIO ON FRI WHILE DRAGGING AN OCCLUSION ACRS THE FA AS ANOTHER LO DVLPS IN THE OHIO VALLEY. EXPANDED AREA OF MIXED PCPN TO INCLUDE RA OVER THE SCNTRL ON THU/THU NGT CONSIDERING THE STRENGTH OF SLY FLOW AHEAD OF DEEP LO TRACKING TO THE W AND ECMWF FCST H85 TEMPS AOA 0C AT 00Z FRI. THEN COLDER FRI-SAT WITH CYC WNW FLOW TO THE S OF LO IN ONTARIO BRINGING LES CHCS. COORDINATED WITH GRB. && .MQT WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING 08Z SUN-00Z TUE MIZ012. WINTER STORM WARNING 12Z SUN-00Z TUE MIZ011-013. SNOW ADVY 12Z SUN-00Z TUE MIZ010. GALE WARNING ALL OF LAKE SUPERIOR. GALE WARNING LAKE MICHIGAN NEAR SHORE AREAS. && $$ KC/KF