AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PHOENIX AZ 555 PM MST SUN FEB 24 2008 SOUTH-CENTRAL AND SOUTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA FORECAST DISCUSSION .SYNOPSIS... A PACIFIC LOW PRESSURE SYSTEM WILL CONTINUE TO WEAKEN AS IT MOVES ACROSS THE WESTERN STATES TONIGHT. A COLD FRONT WILL MOVE ACROSS THE DESERTS THIS EVENING FOR A SLIGHT CHANCE OF SHOWERS MAINLY TO THE NORTH AND EAST OF PHOENIX. HIGH PRESSURE WILL BUILD INTO SOUTHEAST CALIFORNIA AND ARIZONA MONDAY AND TUESDAY FOR SUNSHINE AND WARMER WEATHER. DRY WEATHER AND ABOVE NORMAL TEMPERATURES ARE EXPECTED FOR THE REMAINDER OF THE WEEK. && .SHORT TERM... TONIGHT THROUGH WEDNESDAY... WINDS HAVE INCREASED SUBSTANTIALLY INVOF COLD FRONT OVER FAR WRN ZONES LATE THIS AFTERNOON. HAVE THEREFORE EXPANDED WIND ADVISORY TO INCLUDE ALL OF CA ZONES AND NRN PTN OF LOWER CO RIVER ZONE IN AZ. SEE AWIPS PRODUCT PHXNWPPSR...WMO ID WWUS75 KPSR NPWPSR...FOR LATEST DETAILS. PREVIOUS DISCUSSION... STILL PLENTY OF ENERGY ASSOCIATED WITH THE PASSAGE OF THE TROUGH AND COLD FRONT NOW INTO OUR WESTERN ZONES. ALTHOUGH THERES NOT AS MUCH LIFT FOR OUR CWA COMPARED TO NORTHERN AZ...AN APPROACHING VORT MAX WAS BEGINNING TO AFFECT OUR AREA. IN FACT...LATEST RUC DEPICTED A VORT LOBE STRETCHED OUT FROM NEAR NEEDLES TO LOS ANGELES. SLIGHT INCREASES IN DEW POINTS ARE ALSO LIKELY THIS EVENING...AND HAVE INSERTED SLIGHT CHANCES FOR LIGHT SHOWERS NORTH AND EAST OF THE METRO AREA THROUGH ABOUT MIDNIGHT. WINDS HAVE GENERALLY BEEN LESS THAN EXPECTED...ALTHOUGH WITH THE TIGHTEST GRADIENTS NOW APPROACHING SOUTHEAST CALIFORNIA...WE WILL HOLD ONTO THE WIND ADVISORY FOR JOSHUA TREE NATIONAL PARK INTO THIS EVENING. UPPER RIDGE IS STILL PROGGED FOR MONDAY THROUGH WEDNESDAY...WITH GFS A BIT MORE AGGRESSIVE AND SHOWING HIGHER HEIGHTS THAN LATEST ECMWF. WILL ADJUST TEMPERATURES A BIT TO ACCOUNT FOR THIS SLIGHT ADJUSTMENT IN THE MODELS...WITH SOME SPOTS EXPECTING THE FIRST 80F MAX TEMP OF THE MONTH. && .LONG TERM... WEDNESDAY NIGHT THROUGH SUNDAY... MODELS AGREE IN SHOWING A DEVELOPING DISTURBANCE IN A SPLIT FLOW PATTERN NEAR THE WEST COAST BY THURSDAY. UPPER TROUGH DEEPENS QUITE RAPIDLY BY THURSDAY EVENING...AND PREFER TO GO WITH A COMPROMISE SOLUTION AND A WEAKER TROUGH THAT MOVES THROUGH ARIZONA BY FRIDAY MORNING. THUS...A DRY WEEK IS STILL EXPECTED FOR ALL ZONES...AND EXCEPT FOR SOME MINOR TEMPERATURE ADJUSTMENTS...LOOK FOR NO SIGNIFICANT WEATHER. && .AVIATION... FEBRUARY 25 0055 UTC (FEBRUARY 24 1755 MST) SURFACE FRONT MOVING EWD ACROSS AREA TONIGHT. GUSTY WINDS CURRENTLY UNDERWAY OVER KIPL...30-40KTS...WILL BEGIN TO DIMINISH AFTER ABOUT 03-04Z. LESSER WINDS AT KBLH AND KYUM...20-35KTS...WITH THESE EXPECTED TO DIMINISH AS WELL THIS EVENING. MEANWHILE...KPHX/KIWA WILL EXPERIENCE MUCH LIGHTER WINDS THIS EVENING...MOSTLY LESS THAN 10KTS. NO SIGNIFICANT CLOUDS ANTICIPATED...WITH CIGS GENLY AOA 20K MSL. MOSTLY CIRRUS LEVEL MOISTURE ANTICIPATED FOR MONDAY...WITH MUCH LESS WIND AT WRN TAF SITES. AVIATION DISCUSSION IS NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... FEBRUARY 25 0055Z UTC (FEBRUARY 24 1755 MST) A PACIFIC LOW PRESSURE SYSTEM WILL MOVE ACROSS UTAH AND NORTHERN AZ TODAY. THIS WILL RESULT IN GUSTY SURFACE WINDS THRU TONIGHT...WITH LOCAL GUSTS 40-50 MPH POSSIBLE THRU 03Z. HOWEVER...SUFFICIENT SURFACE MOISTURE WILL PREVENT CRITICAL FIRE WX THRESHOLDS FROM BEING SURPASSED. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...WIND ADVISORY UNTIL 8 PM MST THIS EVENING FOR AZZ020. CA...WIND ADVISORY UNTIL 7 PM PST THIS EVENING FOR CAZ030>033. && $$ NATIONAL WEATHER SERVICE PHOENIX IS ON THE INTERNET AT WEATHER.GOV/PHOENIX SHORT TERM...ESTLE/SIPPLE LONG TERM...SIPPLE AVIATION...ESTLE az AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD CA 155 PM PST MON FEB 25 2008 .DISCUSSION...DEWPOINTS ACROSS THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY AT NOON /20Z/ WERE ONLY A COUPLE OF DEGREES LOWER THAN 20Z SUNDAY. WITH MOSTLY CLEAR SKIES...EXCEPT ALONG THE EAST SIDE AND SOUTH END OF THE VALLEY AND A BUILDING RIDGE ALOFT...THE AIRMASS SHOULD COOL TO SATURATION IN THE PRE-DAWN HOURS WITH AREAS OF FOG DEVELOPING. WILL THEREFORE ISSUE A DENSE FOG ADVISORY FOR THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY FROM 09-17Z WITH THE AFTERNOON FORECAST PACKAGE. SATELLITE LOOPS AND SURFACE OBSERVATIONS SHOW LOW CLOUDS DEVELOPING ALONG THE WEST SIDE OF THE SAN JOAQUIN VALLEY THIS AFTERNOON. THESE CLOUDS ARE FORMING ALONG THE TEMBLORS AND DIABLO RANGE IN A LOW-LEVEL NORTH FLOW OVER THE WEST SIDE OF THE VALLEY...WHICH IS PRODUCING A WEAK EDDY IN WESTERN FRESNO COUNTY NEAR COALINGA WHERE THE ANTICLINE RIDGE SEPARATES PLEASANT VALLEY FROM THE CENTRAL SAN JOAQUIN VALLEY. ALOFT...THE RUC-40 HAS A +8.8 VORTICITY MAXIMUM OVER SOUTHWESTERN FRESNO COUNTY AT 21Z WHICH IS RE-ENFORCING THE SURFACE EDDY AS WELL AS HELPING DRAW CLOUDS FROM THE EAST SIDE ACROSS THE SOUTH END. THIS HAS RESULTED IN A SLIGHT COOLING TREND DUE TO DECREASED SOLAR HEATING. THE GFS AND NAM FORECAST THE STOCKTON-BAKERSFIELD AND SAN FRANCISCO- LAS VEGAS SURFACE PRESSURE GRADIENTS TO BEGIN RELAXING AFTER 00Z TUESDAY...AND THE RUC-40 FORECASTS THE 500-MB VORTICITY TO MOVE SOUTHEAST ACROSS THE SOUTH END OF THE VALLEY IN THE NORTHWEST FLOW ALOFT AHEAD OF THE RIDGE. THIS MAY ALLOW THE CLOUDS TO SLIDE EAST INTO THE SAN JOAQUIN VALLEY...BUT ALSO WILL REDUCE SUPPORT FOR THESE CLOUDS SO EXPECT SOME DISSIPATION OVERNIGHT. SATELLITE LOOPS SHOW THE UPPER-LEVEL RIDGE IN THE EAST PACIFIC BEHIND THE EXITING TROUGH. THE RIDGE IS FORECAST TO BUILD INTO CALIFORNIA OVER THE NEXT 24 HOURS...WITH 500-MB HEIGHTS OVER THE CENTRAL CALIFORNIA INTERIOR RISING TO AROUND 5820 METERS BY 00Z WEDNESDAY. 850-MB TEMPERATURES OVER THE REGION ARE FORECAST TO WARM 4-6 C...AND 1000-500-MB THICKNESSES TO RISE ABOUT 50 METERS. THIS WILL ALLOW TEMPERATURES TO WARM TUESDAY INTO THE MID TO UPPER 60S. THE MODELS BRING A SHORT-WAVE TROUGH INTO THE PACIFIC NORTHWEST WEDNESDAY AND OVER CALIFORNIA WEDNESDAY NIGHT...WITH A CLOSED UPPER- LEVEL LOW DEVELOPING SOUTH OF POINT CONCEPTION THURSDAY. CIRCULATION AROUND THIS LOW WILL PRODUCE A SOUTHERLY FLOW ALOFT OVER THE HANFORD WARNING/FORECAST AREA...AND THIS SHOULD OFFSET ANY COOLING FROM LOWERING HEIGHTS AND THICKNESSES. BOTH THE GFS AND DGEX CONTINUE TO SHOW LIMITED MID-LEVEL /700-500-MB/ MOISTURE WITH THIS TROUGH SO EXPECT ONLY SOME HIGH CLOUDS. THE UPPER-LEVEL RIDGE REBOUNDS INTO CALIFORNIA THURSDAY INTO FRIDAY MORNING...THEN THE RIDGE IS WEAKENED BY THE NEXT UPPER-LEVEL TROUGH DROPPING OUT OF THE GULF OF ALASKA. THE MEDIUM-RANGE MODELS HAVE PROBLEMS WITH THIS SYSTEM...WITH THE GFS AND DGEX FASTER THAN THE ECMWF...AS WELL AS SHALLOWER. CONSENSUS IS TO GO WITH THE FASTER TIMING AND WEAKER SYSTEM...SO WILL KEEP POPS OVER THE NORTHERN HALF OF THE HANFORD WARNING/FORECAST AREA FRIDAY NIGHT AND SATURDAY LIMITED TO 10 PERCENT OR LESS...LEAVING THE FORECAST DRY THROUGH THE PERIOD. && .AVIATION...AS A BUILDING HIGH PRESSURE RIDGE BECOMES THE DOMINATE FEATURE OVER THE WEST COAST...EXPECT A HIGHER POTENTIAL FOR IFR CONDITIONS IN FOG TONIGHT. WHILE MVFR CONDITIONS WILL BE OBSERVED AFTER SUNSET...WILL NOT EXPECT IFR/LIFR CONDITIONS UNTIL AFTER 08Z. IFR/LIFR CONDITIONS WILL EXIST OVER THE VALLEY UNTIL AFTER 18Z TUESDAY. ELSEWHERE...VFR CONDITIONS WILL PREVAIL FOR THE NEXT 24 HOURS. && .AIR QUALITY ISSUES... NONE. && .HNX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY FROM 1 AM TO 9 AM PST TUESDAY FOR THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY /CAZ089>092/. && $$ SANGER/MOLINA WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 240 PM EST MON FEB 25 2008 .SYNOPSIS...LATEST WATER VAPOR/RUC H5 COMPOSITE SHOWS A ZONAL FLOW IN THE MID/UPPER LEVELS ALONG THE SRN TIER OF THE CONUS. THE NEXT WEATHER MAKER FOR OUR REGION WILL BE THE DEEPENING SHORT WAVE TROUGH EMERGING OVER THE CENTER OF THE NATION THIS AFTERNOON. A WEAK SURFACE RIDGE OF HIGH PRESSURE DOMINATES AREAS EAST OF THE MS RIVER...WHILE LOW PRESSURE DEEPENS OVER KS. WINDS ARE VARIABLE LESS THAN 10 MPH...EXCEPT FOR ONSHORE WINDS NEAR THE COAST. AMPLE SUNSHINE AND WARMER THAN NORMAL TEMPS WILL CLOSE OUT THE AFTERNOON. OVER THE COASTAL WATERS...WINDS ARE SLOWLY VEERING AROUND TO ONSHORE...AND SHOULD PICK UP IN SPEED LATER THIS AFTERNOON AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF AN APPROACHING COLD FRONT. && .SHORT TERM (TONIGHT-WEDNESDAY)...12Z NUMERICAL MODEL SUITE IS IN GOOD AGREEMENT THIS PERIOD. THE MID/UPPER TROUGH FROM THE CENTRAL PLAINS TO THE 4-CORNERS REGION WILL PROGRESS EWD INTO THE TN VALLEY AND MID-ATLANTIC THROUGH TUESDAY EVENING. A NRN STREAM SHORT WAVE OVER CENTRAL CANADA WILL DROP SWD AND PHASE WITH THE SRN STREAM TROUGH...RESULTING IN AMPLIFICATION OF THE MEAN ERN CONUS TROUGH. MEANWHILE...THE CENTRAL PLAINS LOW PRESSURE SYSTEM WILL DEEPEN AS IT MOVES ENEWD THROUGH THE OH/TN VALLEYS AND MID-ATLANTIC/NERN STATES DURING THE SAME TIME PERIOD. TIMING OF THE TRAILING COLD FRONT THROUGH THE SERN STATES ON TUESDAY HAS SLOWED SLIGHTLY DURING THE PAST FEW FORECAST CYCLES...WITH THE GFS A TAD FASTER THAN THE NAM. THE FRONT IS PROGGED TO ENTER OUR FL PANHANDLE/SERN AL ZONES MID-LATE MORNING...SWRN GA/WRN FL BIG BEND EARLY-MID AFTERNOON...AND S/CENTRAL GA/ERN FL BIG BEND LATE AFTERNOON-EARLY EVENING. THE POTENTIAL FOR SEVERE WEATHER STILL EXISTS ON TUESDAY...WITH THE ENTIRE CWFA HIGHLIGHTED IN A SLIGHT RISK PER THE SPC DAY2 OUTLOOK. A STRONG SWLY LOW LEVEL JET WILL ADVECT 65-70 DEG DEW POINT AIR INTO THE REGION...UNDER FAIRLY STEEP MID-LEVEL LAPSE RATES. THIS WILL RESULT IN MLCAPES FROM 500-1000 J/KG...WITH VALUES AS HIGH AS 2000 J/KG (PER GFS) CONCENTRATED OVER OUR ERN ZONES TUESDAY AFTERNOON. MODEL SOUNDINGS DEPICT GENERALLY UNIDIRECTIONAL SHEAR PROFILES...WHICH WOULD SUPPORT A QUASI-LINEAR CONVECTIVE SYSTEM (I.E. SQUALL LINE) WITH ORGANIZED BOWING SEGMENTS PRECEDING THE COLD FRONT. THE MAIN THREATS WILL BE DAMAGING WINDS AND LARGE HAIL. A FEW ISOLATED TORNADOES ARE ALSO POSSIBLE ALONG THE LEADING EDGE OF BOWING SEGMENTS AND INVOF BOOKEND VORTICIES. AFTER THE FRONT CLEARS THE CWFA LATER TUESDAY NIGHT...WINDS WILL SHIFT TO THE NORTHWEST. THE TIGHT PRESSURE GRADIENT BEHIND THE FRONT WILL CREATE BRISK CONDITIONS TUESDAY NIGHT INTO WEDNESDAY AS A CANADIAN HIGH PRESSURE SYSTEM USHERS IN A MUCH COLDER AND DRIER AIR MASS. A COLD AIR ADVECTION LIGHT FREEZE EARLY WEDNESDAY MORNING FOR THE NWRN HALF OF THE CWFA...WITH DAYTIME HIGHS REMAINING IN THE 50S. FAVOR THE GFS MOS FOR POPS AND TEMPS. && .LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY)...SURFACE HIGH PRESSURE SETTLES ON TOP OF THE LOCAL AREA WEDNESDAY NIGHT WITH IDEAL RADIATIONAL COOLING CONDITIONS. THIS IS A VERY COLD...DRY AIRMASS AND THE LATEST MEX GUIDANCE IS SHOWING MIN TEMPS IN THE LOWER TO MID 20S MOST INLAND AREAS. WILL STAY A FEW DEGREES ABOVE GUIDANCE FOR NOW. THE SURFACE HIGH MOVES EAST AND A SLOW WARMING TREND BEGINS AS WINDS VEER TO BECOME ONSHORE. HOWEVER...A LIGHT FREEZE IS POSSIBLE OVER A PORTION OF OUR EASTERN ZONES FRIDAY MORNING. A COLD FRONT WILL APPROACH FROM THE NORTHWEST FRIDAY. THE GFS SHOWS THE FRONT WEAKENING SIGNIFICANTLY AND CROSSING OUR CWA DRY FRIDAY NIGHT/EARLY SATURDAY. HIGH PRESSURE BUILDS IN AT THE SURFACE AND ALOFT OVER THE WEEKEND RESULTING IN ABOVE NORMAL TEMPS AND DRY CONDITIONS. THE NEXT STORM SYSTEM DEVELOPS IN TEXAS ON MONDAY. THE GFS SHOWS A CLOSED UPPER LOW DROPPING DOWN INTO WEST TEXAS MONDAY AFTERNOON AND SHIFTING TO NORTHEAST TEXAS BY EVENING. A SURFACE LOW MOVES INTO THE LOWER MISSISSIPPI VALLEY WITH A POTENT SOUTHWARD EXTENDING COLD FRONT BY THE END OF THE PERIOD. THIS MAY MEAN ANOTHER SEVERE WEATHER THREAT LATE MONDAY OR TUESDAY. .MARINE...A WEAK RIDGE OF HIGH PRESSURE OVER THE SOUTHEASTERN STATES WILL MOVE INTO THE ATLANTIC WATERS TONIGHT. A STRONG COLD FRONT WILL MOVE THROUGH THE MARINE AREA ON TUESDAY. INCREASING ONSHORE WINDS AND SEAS WITH SHOWERS AND THUNDERSTORMS WILL PRECEDE THIS COLD FRONT...WITH EVEN STRONGER OFFSHORE FLOW BEHIND THE FRONT. SMALL CRAFT ADVISORY CONDITIONS ARE EXPECTED TUESDAY THROUGH WEDNESDAY... WITH WINDS AND SEAS GRADUALLY SUBSIDING FOR THE REMAINDER OF THE WORK WEEK AS HIGH PRESSURE BUILDS NORTH OF THE COASTAL WATERS. && .AVIATION...AS INCREASINGLY MOIST RETURN FLOW BEGINS TO SET UP OFF THE GULF OF MEXICO TONIGHT WELL OUT AHEAD OF THE APPROACHING COLD FRONT...FOG AND LOW CLOUD DEVELOPMENT IS EXPECTED TO BECOME A MAJOR CONCERN AT THE TERMINALS OVERNIGHT. MUCH OF THE NUMERICAL GUIDANCE AND MODEL CONDENSATIONAL PRESSURE DEFICIT PROGS INDICATE A GOOD POTENTIAL FOR FAIRLY WIDESPREAD IFR/LIFR CONDITIONS...MOST LIKELY IN THE FORM OF LOW CIGS WITH SOME AREAS OF DENSE FOG AS WELL. DETERIORATING CONDITIONS ARE EXPECTED TO BEGIN AROUND 06Z...AND SHOULD LAST THROUGH 12-14Z. ALSO...SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE AT KDHN AND KPFN AS EARLY AS 13-14Z...AND TAF SITES FURTHER EAST AT 15-16Z. && .FIRE WEATHER...BRIEF DURATIONS OF RELATIVE HUMIDITY AT OR BELOW 35 PERCENT ARE EXPECTED THIS AFTERNOON ACROSS THE ERN FL BIG BEND. NO CONCERNS ON TUE WITH MOISTURE AND APPROACHING COLD FRONT. RED FLAG CONDITIONS ARE A GOOD BET BOTH WED AND THU. && .HYDROLOGY...SEVERAL OF OUR RIVER FORECAST POINTS REMAIN IN FLOOD AS A RESULT OF LAST WEEK`S HEAVY RAINS. BOTH VALDOSTA AND THOMASVILLE HAVE CRESTED...WHILE HAVANA IS BEGINNING TO CREST WITH MODERATE FLOODING IMPACTING STATE ROAD 12. MINOR FLOODING IS ALSO OCCURRING AT BLOUNTSTOWN AND MARIANNA. FOR MORE DETAILS...CONSULT LOCAL FLOOD WARNINGS AND FLOOD STATEMENTS FOR RIVER CREST FORECASTS AND POTENTIAL FLOODING IMPACTS. LATEST QPF FROM HPC PREDICTS BASIN AVERAGE RAINFALL AMOUNTS FROM A QUARTER TO HALF INCH WITH ISOLATED HIGHER AMOUNTS ASSOCIATED WITH THIS COLD FRONT. THESE AMOUNTS SHOULD HAVE MINIMAL IMPACT ON THE CURRENT FLOODING SITUATION...BUT WILL CLOSELY MONITOR FOR CHANGES. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 54 72 35 55 26 / 20 60 10 0 0 PANAMA CITY 61 69 39 56 32 / 30 60 10 0 0 DOTHAN 56 64 32 53 28 / 30 70 10 0 0 ALBANY 53 68 34 53 25 / 20 70 10 0 0 VALDOSTA 53 73 38 54 26 / 10 60 20 0 0 CROSS CITY 53 76 41 57 26 / 10 60 40 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...FIRE WEATHER WATCH WEDNESDAY AFTERNOON FOR THE FOLLOWING ZONES: COFFEE...DALE...GENEVA...HENRY...HOUSTON. GA...FIRE WEATHER WATCH WEDNESDAY AFTERNOON FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...BROOKS...CALHOUN...CLAY... COLQUITT...COOK...DECATUR...DOUGHERTY...EARLY...GRADY... IRWIN...LANIER...LEE...LOWNDES...MILLER...MITCHELL... QUITMAN...RANDOLPH...SEMINOLE...TERRELL...THOMAS...TIFT... TURNER...WORTH. FL...FIRE WEATHER WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING FOR THE FOLLOWING ZONES: BAY...CALHOUN...DIXIE... FRANKLIN...GADSDEN...GULF...HOLMES...INLAND WALTON... JACKSON...JEFFERSON...LAFAYETTE...LEON...LIBERTY... MADISON...TAYLOR...WAKULLA...WASHINGTON. GM...SMALL CRAFT ADVISORY FROM 8 AM TUESDAY TO 7 PM EST WEDNESDAY FOR THE FOLLOWING ZONES: APALACHEE BAY OR COASTAL WATERS FROM KEATON BEACH TO OCHLOCKONEE RIVER FL OUT TO 20 NM...COASTAL WATERS FROM OCHLOCKONEE RIVER TO APALACHICOLA FL OUT TO 20 NM...COASTAL WATERS FROM SUWANNEE RIVER TO KEATON BEACH OUT 20 NM...COASTAL WATERS FROM APALACHICOLA TO DESTIN FL OUT 20 NM...WATERS FROM SUWANNEE RIVER TO APALACHICOLA FL FROM 20 TO 60 NM...WATERS FROM APALACHICOLA TO DESTIN FL FROM 20 TO 60 NM. && $$ JAMSKI/GOULD fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 915 AM EST MON FEB 25 2008 .SYNOPSIS...LATEST WATER VAPOR/RUC H5 COMPOSITE SHOWS ONE SHORT WAVE TROUGH EXITING SRN NEW ENGLAND/MID-ATLANTIC COAST...WITH THE NEXT UPSTREAM SHORT WAVE EMERGING OVER THE CENTRAL PLAINS. BETWEEN THESE TWO SYSTEMS...ZONAL FLOW PREVAILS OVER THE GULF COAST STATES THIS MORNING. THE LOCAL 12Z SOUNDING DEPICTED A SHALLOW INVERSION JUST ABOVE THE SURFACE...WITH A MORE SUBSTANTIAL ONE NEAR 750 MB. AT THE SURFACE...A WEAK RIDGE OF HIGH PRESSURE DOMINATED AREAS FROM THE MS RIVER EWD. EXPECT ANOTHER CHAMBER OF COMMERCE TYPE DAY WITH AMPLE SUNSHINE AND WARMER THAN NORMAL AFTERNOON TEMPS. && .MARINE...CURRENT OBS SHOW NLY WINDS 10 KTS OR LESS WITH LOW SEAS. NO SIGNIFICANT CHANGES ARE ANTICIPATED FOR THE MORNING FORECAST UPDATE...WITH WINDS VEERING AROUND TO ONSHORE THIS AFTERNOON. LOOKS LIKE AN IDEAL DAY FOR BOATING BEFORE CONDITIONS DETERIORATE TONIGHT. && .AVIATION...VFR CONDITIONS WILL PREVAIL UNTIL EVENING AT TERMINALS. THEN MVFR CIGS/VSBYS ARE EXPECTED TO DEVELOP LATER TONIGHT...WITH IFR OR LOWER RESTRICTIONS AT KTLH AND KVLD. HAVE INCLUDED TEMPO GROUPS FOR LIGHT RAIN AT KDHN AND KABY AFTER 09Z TUE. && .FIRE WEATHER...BRIEF DURATIONS OF RELATIVE HUMIDITY AT OR BELOW 35 PERCENT ARE EXPECTED THIS AFTERNOON ACROSS THE ERN FL BIG BEND. NO CONCERNS ON TUE WITH MOISTURE AND APPROACHING COLD FRONT. RED FLAG CONDITIONS ARE A GOOD BET BOTH WED AND THU. && .HYDROLOGY...SEVERAL OF OUR RIVER FORECAST POINTS ARE IN FLOOD AS A RESULT OF LAST WEEK`S HEAVY RAINS. BOTH VALDOSTA AND THOMASVILLE HAVE CRESTED...WHILE HAVANA IS BEGINNING TO CREST WITH MODERATE FLOODING IMPACTING STATE ROAD 12. FOR DETAILS...CONSULT LOCAL FLOOD WARNINGS AND FLOOD STATEMENTS FOR RIVER CREST FORECASTS AND POTENTIAL FLOODING IMPACTS. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 75 55 70 37 54 / 00 20 80 20 00 PANAMA CITY 71 61 69 39 53 / 05 30 70 10 00 DOTHAN 71 56 62 34 52 / 05 50 70 10 00 ALBANY 73 55 65 32 52 / 00 40 80 10 00 VALDOSTA 74 54 70 37 52 / 00 20 80 20 00 CROSS CITY 76 56 74 41 54 / 00 10 80 30 00 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$ JAMSKI/DUVAL fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 833 PM EST SUN FEB 24 2008 .DISCUSSION... CURRENTLY/TONIGHT...WATER VAPOR/RUC ANALYSIS SHOWS EXTENSIVE DRYING ALOFT BEHIND UPPER TROUGH AXIS PASSING OFF THE SOUTHEAST U.S. COAST. CANAVERAL WIND PROFILER SHOWING WESTERLY FLOW IN THE LOW LEVELS AND SURFACE ANALYSIS SHOWS DRIER AIR ASSOCIATED WITH FRONTAL TROUGH ACROSS NORTHERN SECTIONS. THE GFS SHOWS LOWER THETA E VALUES PUSHING GRADUALLY SOUTH OVERNIGHT. THIS SHOULD RESULT IN LITTLE CLOUD COVER. THE CHANCES FOR FOG/STRATUS SHOULD BE LOWER THAN 24 HOURS AGO DUE TO THE DRY AIR ADVECTION AND BOUNDARY LAYER WINDS OF AT LEAST 15 KNOTS...BUT WILL LEAVE MENTION OF PATCHY FOG IN THE FORECAST. && .AVIATION...MODELS SHOW DRIER AIR ADVECTING SOUTHWARD AS WEAK COLD FRONT GETS NUDGED SOUTH OF THE AREA. LAMP GUIDANCE HAS TRENDED UPWARD ON VISIBILITIES...SO WE ARE NOT PLANNING ON IFR CONDITIONS. THE DRIER AIR WILL BE SLOWEST TO REACH SOUTHERN SECTIONS...SO ANY FOG/CEILING PROBLEMS WOULD BE THERE. MONDAY WILL BE VFR WITH LIGHT NORTHWEST WINDS AND A SEA BREEZE ALONG THE COAST. && .MARINE...WEAK LOW PRESSURE IS FORECAST TO DEVELOP TO OUR NORTHEAST TONIGHT AND VEER THE WINDS TO THE NORTHWEST. SPEEDS SHOULD BE 15 KNOTS OR LESS BUT THE FLOW MAY BE 10-15 KNOTS ACROSS THE NORTH/OFFSHORE WATERS MON MORNING BEFORE WEAKENING IN THE AFTERNOON. STILL THE SEA CONDITIONS SHOULD BE OK CLOSE TO THE COAST DUE TO A WIND TRAJECTORY OFF THE LAND...BUT MAY BE 3-4 FEET BEYOND 20NM. NOTE TO MARINERS: BUOY 41009 IS ADRIFT AND DATA IS NOT REPRESENTATIVE OF CONDITIONS 20 MILES EAST OF PORT CANAVERAL. THEREFORE THE DATA HAS BEEN REMOVED FROM OUR NOAA WEATHER RADIO BROADCAST. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM/AVIATION...LASCODY LONG TERM....GLITTO fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 718 PM CST MON FEB 25 2008 .DISCUSSION...EVENING UPDATE 710 PM CST RATHER COMPLICATED FORECAST SCENARIO UNFOLDING THIS EVENING. UPPER LEVEL TROUGH CONTINUES TO TRACK EAST ACROSS IOWA AND NORTHWEST MISSOURI THIS EVENING. MID LEVEL FRONTOGENESIS BAND CONTINUES TO SHIFT SLIGHTLY SOUTHWARD THIS EVENING...AND ENHANCED REFLECTIVITIES NOW SETTING UP FROM NEAR THE QUAD CITIES THROUGH THE WESTERN SUBURBS OF CHICAGO INTO THE DOWNTOWN CHICAGO AREA WHERE REPORTS OF MODERATE SNOW ARE CURRENTLY BEING RECEIVED. REPORTS FROM FAR NORTHERN ILLINOIS INDICATE GENERALLY 1 TO 2 INCHES OF SNOW HAS FALLEN THROUGH 7 PM THIS EVENING. RADAR HAS INDICATED SOUTHWARD EXPANSION OF REFLECTIVITIES INTO THE INTERSTATE 80 CORRIDOR LIKELY IN RESPONSE TO FAIRLY STRONG ISENTROPIC LIFT SOUTH OF THE STRONGER MID LEVEL FRONTOGENESIS. SHORT TERM RUC/WRF PROGS TAKE THIS STRONGER ISENTROPIC UPGLIDE INTO NORTHWEST INDIANA BY AROUND 03Z...AND EAST OF THE AREA AFTER 06Z. CONCERN IS THAT WITH STRONGER MID LEVEL FRONTOGENESIS AXIS SAGGING SOUTHWARD...AND ISENTROPIC UPGLIDE SHIFTING EASTWARD...COUNTIES ADJACENT TO ILLINOIS/WISCONSIN STATELINE MAY HAVE A DIFFICULT TIME REACHING WARNING CRITERIA AMOUNTS. HOWEVER...JUST A BIT FURTHER TO THE SOUTH ALONG THE INTERSTATE 88 CORRIDOR...SPOTTER REPORTS HAVE BEEN RECEIVED OF SNOWFALL RATES OF AN INCH PER HOUR IN ASSOCIATION WITH FRONTOGENESIS FORCING. WILL GRADUALLY SEE FAVORED AREA OF HEAVY SNOW SHIFT SOUTHWARD THROUGH THE LATE EVENING AND OVERNIGHT AS THE UPPER LEVEL WAVE TRACKS OFF TO THE EAST. IT DOES APPEAR POSSIBLE THAT MANY LOCATIONS IN THE WARNING MAY END UP WITH BELOW WARNING CRITERIA SNOWFALL...ALTHOUGH GIVEN FRONTOGENETIC FORCING NATURE AND LOCALIZED HEAVY SNOWFALL RATES...ALONG WITH INCREASING NORTH WINDS OVERNIGHT AND POTENTIAL FOR BLOWING AND DRIFTING...WILL NOT MAKE ANY CHANGES TO GOING WINTER STORM WARNING HEADLINE AT THIS TIME. MARSILI && .AVIATION... 556 PM CDT... 0000 UTC TAFS...FOCUS REMAINS WITH SFC LOW SLIPPING EAST ACROSS THE MS VLY SOUTH ST LOUIS THIS EVENING AND ALONG THE OH RVR VLY THRU TUESDAY. WRAPAROUND MSTR INUNDATING AREA WITH RAIN AND SLEET EARLIER TODAY SHUD BE CHANGING OVER TO SNOW AS COLD AIR IS PULLED DOWN INTO NRN IL/INDY AS WINDS SHIFT TO THE NE. IFR CIGS AND FRQ IFR VSBLY IN SNOW WILL DOMINATE FORECAST OVERNIGHT WITH WINDS CONTINUING TO BACK TO NORTH AFTER MIDNGT AND SPEEDS PICKING UP TO 25 KTS AT THAT TIME AND CONTINUING TO BUILDS GUSTS TO 35 KNOTS BY MRNG. DEEPER WRAPAROUND MSTR PULLING OUT TO THE EAST AROUND DAYBREAK AND SNOWFALL LESSENING TO FLURRIES BFR NOON. HOWEVER NORTH WINDS TO 35 KTS LIKELY ALL DAY TUESDAY WITH BLOWING SNOW MORE THAN SNOWFALL BEING A VSBY PROBLEM. CIGS LIFTING TO MVFR IN THE MRNG AND EVEN VFR IN THE AFTERNOON...BUT VSBY BLO 3 MI EXPECTED UNTIL NOONTIME IN BLOWING SNOW AND FINALLY LIFTING TO VFR LATE IN THE AFTN WHEN WINDS SUBSIDE TO 25 KTS TOWARD EVENING. RLB && .MARINE... 203 PM CST SOME DISCUSSION THIS AFTERNOON WITH NEIGHBORING OFFICES ABOUT EXPIRATION OF GALE WARNING A LITTLE EARLIER TUESDAY EVENING...BUT FOR NOW WILL KEEP IT GOING UNTIL MIDNIGHT. SFC AND BLYR WINDS AND GUSTS DO DROP OFF PRETTY QUICKLY TUESDAY EVENING AS PRESSURE GRADIENT WEAKENS AHEAD OF RIGDE BUILDING IN THE PLAINS. IN THE MEANTIME...WINDS HAVE STARTED TURNING TO THE SOUTHEAST THIS AFTERNOON WITH THE INFLUENCE OF SFC LOW APPROACHING FROM EASTERN KANSAS. WINDS WILL CONTINUE TURNING TO THE NORTHEAST THIS EVENING AND THEN TO THE NORTH BY MORNING AS THEY INCREASE TO GALE STRENGTH. BY WEDNESDAY NIGHT THE SFC RIDGE WILL SETTLE OVER THE AREA AND BRING LIGHT NORTHWEST WINDS AND REDUCED CLOUDINESS BEFORE THE NEXT STORM SYSTEM APPROACHES EARLY FRIDAY. LENNING && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING UNTIL 12 PM CST TUESDAY FOR ILZ003>006-008- 010>014-019>023-032. WINTER STORM WARNING UNTIL 4 PM CST TUESDAY FOR ILZ033-039. IN...WINTER STORM WARNING UNTIL 4 PM CST /5 PM EST/ TUESDAY FOR INZ001-002-010-011-019. LM...GALE WARNING FROM MIDNIGHT TONIGHT TO MIDNIGHT CST TUESDAY NIGHT FOR LMZ740>745-777-779. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1200 PM CST SUN FEB 24 2008 .DISCUSSION... ISSUED 1045 AM CST SUN FEB 24 2008 UPDATED THE FORECAST DURING MID MORNING TO REMOVE THE FREEZING FOG ADVISORY OVER CHAMPAIGN AND VERMILION COUNTIES THAT EXPIRED AT 9 AM. ALSO INCREASED LIGHT SNOW CHANCES SOUTH OF I-72 THIS MORNING WITH LIKELY CHANCES FROM I-70 SOUTH WHERE 1 TO 2 INCHES OF SNOW POSSIBLE. WILL UPDATE THE FORECAST AGAIN AROUND NOON TO REMOVE CHANCES OF LIGHT SNOW SOUTH OF I-72 AS THIS AFTERNOON SHOULD BE DRY. WILL COOL HIGHS A BIT ESPECIALLY IN SOUTHERN AREAS WHERE LOW CLOUDS LINGER. 552 DM 500 MB LOW OVER SOUTHERN INDIANA AND MOVING EAST. THIS SYSTEM PRODUCED SOME LIGHT SNOW SOUTH OF I-72 AS FAR NORTH AS TAYLORVILLE AND PARIS THIS MORNING. LIGHT SNOW HAD DIMINISHED BY LATE MORNING BUT STILL GETTING REPORTS OF SOME LIGHT SNOW WITH VSBYS 1 TO 3 MILES FROM CHARLESTON/MATTOON SE WITH LAWRENCEVILLE GETTING 1/2 MILE IN MODERATE SNOW AT 10 AM. HAD REPORTS OF 1 TO 2 INCHES OF SNOW SOUTH OF I-70 THIS MORNING WITH FLORA GETTING 2 INCHES AT 830 AM. DENSE FREEZING FOG LIFTED AROUND 8 AM IN CHAMPAIGN AND DANVILLE BUT STILL GETING A LIGHT FOG/HAZE WITH VSBYS 3 TO 5 MILES FROM I-72 SOUTH LATE THIS MORNING. PARTLY TO MOSTLY SUNNY SKIES NORTH OF I-72. TEMPS WERE IN THE UPPER 20S AND LOWER 30S EXCEPT LOWER 20S BY CHAMPAIGN AND DANVILLE WHERE THERE WAS DENSE FREEZING FOG EARLIER THIS MORNING. WINDS WERE LIGHT YET...EITHER CALM OR LIGHT EAST TO SOUTH. 16Z/10 AM SURFACE MAP SHOWS 1024 MB HIGH PRESSURE OVER SOUTHERN OHIO AND RIDGING WEST INTO CENTRAL/SOUTHERN IL/MO AND HELPING TO KEEP THE WINDS LIGHT. RUC13...WRF12 AND SHEF MODELS WEAKEN UPPER LEVEL LOW AS IT MOVES EAST FROM SOUTHERN INDIANA INTO SE OHIO BY SUNSET. SURAFCE HIGH PRESSURE SETTLES OVER THE SE STATES WHILE SURFACE LOW DEEPENS TO 1000 MB OVER WESTERN KS BY 12Z/MON. SSW WINDS 5 TO 10 MPH DEVELOP OVER CENTRAL IL ON BACK SIDE OF HIGH PRESSURE. BUT ABUNDANT LOW CLOUDS FROM I-72 SOUTH TO KEEP TEMPS FROM WARMING UP AS MUCH. SATELLITE LOOP SHOWS BROKEN TO OVERCAST LOW CLOUDS DRIFTING ENE INTO CENTRAL IL SO SKEPTICAL IF SKIES WILL BECOME PARTLY SUNNY SOUTH OF I-72 THIS AFTERNOON. WILL HAVE HIGHS IN THE UPPER 30S AND GALESBURG MAY BE THE MILD SPOT TODAY SEEING THE MOST SUNSHINE. HUETTL && .AVIATION... ISSUED 1155 AM CST SUN FEB 24 2008 BROKEN LOW CLOUDS OF 1.5 TO 3K FT FROM I-72 SOUTH MAY SCATTER OUT FOR A TIME THIS AFTERNOON ALONG I-72. BUT INCREASING SSW FLOW AROUND RETREATING HIGH PRESSURE FROM THE OHIO VALLEY INTO THE SE STATES TONIGHT WILL LIFT LOW CLOUDS BACK NORTH EARLY THIS EVENING...REACHING I-74 AROUND 03Z WITH CEILINGS LOWING TO 1 TO 2K FT OVERNIGHT. CMI AND DEC STILL SEEING SOME FOG WITH VSBYS 2 TO 4 MILES AND THIS SHOULD LIFT BY 20Z. LIGHT FOG EXPECTED TO RETURN TO CENTRAL IL TONIGHT INTO MON MORNING...AND VSBYS COULD GET TO 1 TO 3 MILES AT DEC...BMI AND CMI OVERNIGHT. A 1000 MB LOW PRESSURE DEVELOPS OVER WESTERN KS BY 12Z MON AND DEEPENS TO NEAR 997 MB OVER CENTRAL KS BY 18Z/MON. THIS INCREASES SOUTH WINDS TO 10 TO 15 KTS OVER CENTRAL IL. RAIN SHOULD STAY WEST OF CENTRAL IL TAF SITES THROUGH 18Z/MON AND ARRIVING FROM THE WEST DURING MON AFTERNOON. WRF MODELS LIFTS LOW CLOUDS NORTH OF I-74 BY 18Z/MON BUT THIS MIGHT BE A BIT QUICK AND KEPT BROKEN TO OVERCAST LOW CLOUDS OF 1 TO 2K FT IN AREA. HUETTL && .PREV DISCUSSION... ISSUED 253 AM CST SUN FEB 24 2008 MAIN SHORT-TERM ISSUE WILL BE LOW POPS ACROSS THE FAR SOUTHERN KILX CWA TODAY...AS AN UPPER LEVEL DISTURBANCE SKIRTS BY JUST TO THE SOUTH. IN THE LONGER-TERM...MAIN SYSTEM STILL ON TRACK FOR LATE MONDAY INTO TUESDAY. 08Z SURFACE CHART SHOWS HIGH PRESSURE CENTERED OVER THE OHIO VALLEY...WITH WEAK RETURN FLOW NOTED ACROSS CENTRAL ILLINOIS. MEANWHILE...TROUGH OF LOW PRESSURE IS TRACKING TOWARD THE MID MISSISSIPPI VALLEY...BRINGING LIGHT SNOW TO PARTS OF MISSOURI AND SOUTHERN ILLINOIS. ALOFT...ACTIVE PATTERN NOTED ACROSS THE CONUS...WITH POTENT SHORT-WAVE OVER MISSOURI/OKLAHOMA AND CLOSED LOW SPINNING OFF THE COAST OF NORTHERN CALIFORNIA. SHORT TERM...TODAY THROUGH TUESDAY LATEST RADAR MOSAIC CONTINUES TO SHOW BAND OF LIGHT SNOW LIFTING N/NE ACROSS SOUTHERN ILLINOIS TOWARD THE SE KILX CWA. NORTHERN FRINGE OF THE PRECIP SHIELD IS NOT REACHING THE GROUND...AS IT ENCOUNTERS A DRY ENVIRONMENT TO THE NORTH. BASED ON SURFACE OBS...SNOW HAS NOW REACHED A SAINT LOUIS TO EVANSVILLE LINE AND SHOULD CONTINUE TO PIVOT NORTHWARD AS THE MORNING PROGRESSES. RUC/NAM-WRF SEEM TO HAVE THE BEST HANDLE ON THE QPF FIELD AT THIS POINT...AND BOTH MODELS BRING LIGHT SNOW AS FAR NORTH AS AN EFFINGHAM TO ROBINSON LINE THIS MORNING. WILL THEREFORE CARRY 30 POPS FOR LOCATIONS SOUTH OF I-70 THROUGH NOON...BEFORE THE SYSTEM QUICKLY DEPARTS THIS AFTERNOON. ELSEWHERE AROUND CENTRAL ILLINOIS...A PERSISTENT AREA OF DENSE FOG AROUND CHAMPAIGN/DANVILLE WILL GRADUALLY BURN OFF BY MID-MORNING...FOLLOWED BY PARTLY SUNNY SKIES. WITH LIGHT S/SW FLOW EXPECTED...TEMPS WILL RISE A FEW DEGREES HIGHER THAN YESTERDAY. WILL CONTINUE TO UNDERCUT MAV GUIDANCE NUMBERS BY A COUPLE OF DEGREES...YIELDING HIGHS MAINLY IN THE UPPER 30S ACROSS THE REGION. AFTER A MOSTLY CLEAR EVENING...CLOUDS WILL ONCE AGAIN BE ON THE INCREASE DURING THE OVERNIGHT HOURS...AS THE NEXT SYSTEM QUICKLY APPROACHES FROM THE WEST. 00Z 24 FEB MODELS IN EXCELLENT AGREEMENT CONCERNING THE TIMING AND TRACK OF THIS FEATURE...EXCEPT FOR THE NAM-WRF...WHICH CONTINUES TO BE THE FURTHEST NORTH. FOLLOWING THE GFS/ECMWF/CANADIAN CONSENSUS...AN AREA OF LOW PRESSURE WILL TRACK FROM CENTRAL KANSAS TO NEAR SAINT LOUIS BY MONDAY EVENING...THEN INTO SOUTHERN OHIO BY TUESDAY MORNING. PLENTY OF WARM AIR WILL BE PULLED UP FROM THE SOUTH IN ADVANCE OF THIS SYSTEM...SO PRECIP WILL INITIALLY BE IN THE FORM OF RAIN. WILL CONTINUE TO CARRY CHANCE FOR RAIN/SNOW DURING THE MORNING ACROSS THE WESTERN CWA...WITH RAIN EVERYWHERE BY AFTERNOON. HIGHEST POPS WILL BE NORTH OF THE LOW TRACK ACROSS THE CENTRAL AND NORTHERN CWA...WITH LOWER POPS FURTHER SOUTH. DECENT LOW-LEVEL JET DEVELOPS IN ADVANCE OF THE LOW AND ITS TRAILING COLD FRONT MONDAY EVENING. THIS...COUPLED WITH GOOD CONVERGENCE ALONG THE BOUNDARY AND STRONG UPPER DYNAMICS ASSOCIATED WITH APPROACHING WAVE...MAY SET OFF A FEW THUNDERSTORMS ALONG AND SOUTH OF THE LOW TRACK ACROSS THE SE CWA. MEANWHILE...FURTHER NORTH ACROSS CENTRAL ILLINOIS...RAIN WILL BECOME MORE WIDESPREAD DURING THE EVENING. AS COLDER AIR IS GRADUALLY DRAWN SOUTHWARD ON THE BACK SIDE OF THE SYSTEM...THE RAIN WILL CHANGE TO SNOW FROM NORTHWEST TO SOUTHEAST AFTER MIDNIGHT. LIGHT SNOW WILL PERSIST ACROSS CENTRAL ILLINOIS INTO TUESDAY MORNING...ESPECIALLY ALONG AND NORTH OF A QUINCY TO CHAMPAIGN LINE. BEFORE THE SNOW ENDS...A LIGHT ACCUMULATION IS EXPECTED ACROSS THE ENTIRE AREA...WITH THE HIGHEST AMOUNTS ACROSS THE NORTH. MOST LOCATIONS SHOULD PICK UP BETWEEN ONE AND TWO INCHES...WITH AREAS ALONG AND NORTH OF A RUSHVILLE TO BLOOMINGTON LINE RECEIVING BETWEEN 2 AND 4 INCHES. BLUSTERY AND COLDER CONDITIONS WILL PREVAIL ON TUESDAY...WITH HIGH TEMPS STRUGGLING TO RISE MUCH ABOVE EARLY MORNING LOWS. LONG TERM...WEDNESDAY THROUGH SATURDAY CHILLY WEATHER WILL PERSIST WEDNESDAY AND THURSDAY...AS THE REGION REMAINS UNDER THE INFLUENCE OF NORTHWESTERLY UPPER-LEVEL FLOW. NEXT CLIPPER SYSTEM STILL SLATED TO IMPACT ILLINOIS LATE THURSDAY INTO FRIDAY. GFS/ECMWF ARE QUITE SIMILAR WITH THIS WEAK FEATURE...HOWEVER ECMWF IS A BIT FURTHER NORTH AND KEEPS CENTRAL ILLINOIS LARGELY DRY. MEANWHILE...GFS SUGGESTS A PERIOD OF LIGHT SNOW LATE THURSDAY AFTERNOON AND NIGHT...FOLLOWED BY PERHAPS A FEW SHOWERS ON FRIDAY AS A COLD FRONT SWINGS THROUGH THE AREA. AT THIS POINT...WILL NOT MAKE ANY MAJOR CHANGES TO THE CURRENT FORECAST FOR THIS SYSTEM...WITH A CHANCE FOR LIGHT SNOW THURSDAY NIGHT. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1043 PM EST MON FEB 25 2008 .UPDATE... ...WINTER STORM STILL LOOKS TO BE POTENT OVERNIGHT INTO TUESDAY... ...INTERNET ISSUES HOPING TO BE RESOLVED SOON... TWO MAIN CONCERNS TONIGHT WITH THE UPDATE...ONE THE MUCH FASTER TRANSITION TO SNOW ACROSS THE REGION. TWO...SIGNIFICANT MID LEVEL CIRCULATION...WITH AMPLE MOISTURE STREAMING NORTH FROM THE GULF COMBINED WITH STEEPENING MID LEVEL LAPSE RATES MAY CREATE CONDITIONS RIPE FOR THUNDERSNOW. OVERALL THE FORECAST LOOKS GREAT AT THIS TIME...SNOWFALL RATES HAVE REALLY STARTING TO SHOOT UP AS THE BETTER FORCING ENTERS THE REGION. ACARS SOUNDING FROM 0207Z FROM INDY SHOWS THAT THE WARM LAYER WAS FAIRLY SHALLOW THERE...WOULD EXPECT WITH DYNAMICAL COOLING THAT WE WILL NOT HAVE A REVERT BACK TO LIQUID PRECIP. RATES NEARING MORE THAN ONE INCH PER HOUR IN THE HEAVIER BANDS AS PER REPORTS FROM SPOTTERS. LATEST RUC AND NAM12 CONTINUES TO SHOW STRONG FRONTO FORCING ACROSS NORTHERN INDIANA AND NORTHWEST OHIO THRU THE OVERNIGHT AND INTO THE MORNING. BUFKIT SHOWING OMEGAS BULLSEYED IN THE SNOW GROWTH REGION FOR MUCH OF THE NEXT 6-12 HOURS. TIME HEIGHT SERIES SHOWS SOLID AMOUNTS OF NEG EPV ACROSS THE REGION THRU THE OVERNIGHT AND INTO TUES MORN...WITH DECENT LAPSE RATES THE LIKELIHOOD OF THUNDERSNOW IS AT LEAST IN THE CHC CATEGORY(30-50 PERCENT THAT IT WILL HAPPEN SOMEWHERE IN THE AREA). EVEN IF THAT IS NOT THE CASE...ENOUGH CONVECTIVE ELEMENTS IN PLAY FOR SIGNIFICANT BANDING TO CONTINUE. HAVE RAISED THE LOCALLY HIGHER AMOUNTS IN WSW TO 10 TO 12 INCHES. IT IS POSSIBLE THAT WE WILL NEED TO RAISE AMOUNTS ACROSS MUCH OF THE AREA OVERNIGHT FOR TOTAL SNOWFALL...HAVE HELD WHAT WAS INHERITED BUT IT IS POSSIBLE THAT IT IS NOT ENOUGH GIVEN CURRRENT SNOWFALL RATES. THE OVERNIGHT CREW MAY NEED TO BUMP THE ADVISORY COUNTIES INTO FULL BLOWN WINTER WARNINGS...THOUGH A BRIEF LULL THERE MAY OCCUR AS THE WAA PRECIP TRANSITS EAST AND THE PRECIP ASSOCIATED WITH THE MID LEVEL CIRCULATION/TROWAL WORKS EAST INTO THE REGION. && .PREV DISCUSSION... /ISSUED 639 PM EST MON FEB 25 2008/ AVIATION (00Z TAFS)... DETERIORATING FLIGHT CONDITIONS ACROSS THE REGION TONIGHT INTO TUESDAY. MVFR OR IFR CONDITIONS ACROSS THE ENTIRE REGION AT THIS TIME...NO IMPROVEMENT EXPECTED THROUGH THE PERIOD. PRECIP WILL BECOME MORE LIKELY THROUGH THE NEXT FEW HOURS...WITH BRIEF SLEET/RAIN/SNOW MIX POSSIBLE...BUT ALL SNOW LIKELY BY 02-04Z. VSBYS AND CIGS WILL BE LOW WITH VSBYS AS LOW AS 1/4 TO 1/2SM AT TIMES THROUGH THE EARLY AFTERNOON ACROSS THE REGION...AND CIGS AS LOW AS 200-400 FEET. BLOWING SNOW WILL BE A CONCERN AS WINDS START TO INCREASE FROM THE NORTH AS WE APPROACH 10-12Z...AND WILL CONTINUE THROUGH THE REST OF THE PERIOD. PREV DISCUSSION... /ISSUED 522 PM EST MON FEB 25 2008/ SHORT TERM... TONIGHT AND TUESDAY. MODEL TRENDS FAVORING A FURTHER SOUTHERN TRACK. SOME FAVORING OF NAM/SREF WITH RESPECT TO MORE PLAUSIBLE SURFACE LOW TRACK. ECMWF TAKING SFC LOW STRAIGHT THROUGH WV APPALACHIA NOT LIKELY GIVEN CURRENT THERMAL GRADIENT PARALLEL TO TOPOGRAPHIC ISOPLETHS. LATEST GFS A RESPECTABLE MIDDLE OF ROAD TRACK. MOISTURE LADEN WAVE OVER NATION MIDSECTION TO APPROACH OVERNIGHT AND BE FURTHER ENERGIZED BY NRN STREAM WAVE CLEARLY EVIDENT IN WV IMAGERY QUICKLY DIVING SSE THROUGH DAKOTAS/MN AS MID/UL HGHTS CONTINUE TO STRONG BUILD WITH 120-140M/12 HR 5H HEIGHT RISES OVER CA/OR TODAY/TONIGHT. MODEL CONSENSUS FOR FURTHER SOUTH TRACK APPEARS PLAUSIBLE AS SYSTEM TAKES SHAPE OVERNIGHT. BY 06-08 UTC TREMENDOUS LIFT/DYNAMIC COOLING ACROSS CWA SHOULD COOL COLUMN TO SHIFT PRECIP TO SNOW. I290K ISENT UPGLIDE INTO SRN IN TREMENDOUS 06-09 UTC FOLLOWED BY NEAR 2 G/KG THROUGH STRONG SW-NE ORIENTED MID LEVEL INTO SRN/SERN CWA THROUGH DEEP DENDRITIC GROWTH ZONE SHOULD DELIVER SNOWFALL RATES OF 1-2 INCH PER HOUR THROUGH SW 2/3RD OF CWA WITH FAR SRN/SERN ZONES CLOSEST TO 7H LOW TRACK WITH HIEST AMOUNTS...SHOULD EARLY CHANGEOVER INDEED OCCUR PAN OUT. BLSN ALSO A FACTOR AS NRLY WINDS INCREASE...FAR NORTH CWA SNOW RATIOS SHOULD BE FAIRLY HIGH THROUGH THE EVENT...ELSEWHERE LOW RATIOS 8-1 OR LESS INCREASING TO 15-1 BY END OF EVENT TO GIVE VARYING DEGREE OF BLSN IMPACT. UPGRADE OF WATCH TO SN/BLSN ADVISORY IN FAR NWRN ZONES WITH LESSER AMOUNTS/MORE ACCUSTOMED TO MAJOR SNOW EVENTS...WINTER STORM WARNING REMAINDER OF CWA. LONG TERM...TUESDAY NIGHT THROUGH MONDAY... MAIN CONCERN THIS PERIOD LIES WITH LES POTENTIAL TUE NITE THRU THU MORNING. VERY COLD AIR WILL MOVE IN BEHIND EXITING SYSTEM AND SET THE STAGE FOR POSSIBLY SIGNIFICANT LAKE EFFECT SNOW EVENT. NAM HAS BEEN FAIRLY CONSISTENT IN SHOWING IMPRESSIVE SINGLE BAND OVR WRN CWA SETTING UP BTW 00Z-06Z WED AND LASTING UNTIL NEARLY 18Z BEFORE MOVING EAST AND EVENTUALLY REORGANIZING IN SRN LOWER MI AFTER 00Z THU. AS USUAL, GREATEST CONCERN IN LAPORTE...ST JOSEPH, IN...AND BERRIEN COUNTIES BUT ALSO WORRIED ERN STARKE AND MARSHALL WILL GET INTO THE ACTION IF A DOMINANT SINGLE BAND DOES SET UP. NO SIG LIMITING FACTORS TO BE SEEN WITH DELTA T/S NEAR 20C...INVERSION HTS AOA 5KFT...UNIDIRECTIONAL FLOW BELOW 40 KTS AT 350 DEG FOR A SUBSTANTIAL AMOUNT OF TIME VEERING TO 290 BY END OF EVENT...GOOD SYNOPTIC SCALE MOISTURE BLO INVERSION...AND THE POSSIBILITY OF A LK SUPERIOR CONNECTION TO BOOT. BIG Q IS TOTAL ACCUMS AND EXTENT SOUTH THE BAND COMES INLAND. FOR NOW...WILL HOIST LAKE EFFECT SNOW WATCH 05Z-22Z WED IN LAPORTE...ST JOE, IN...AND BERRIEN WITH 6+ INCHES POSSIBLE. TOYED WITH ALSO THROWING MARSHALL COUNTY IN AS THIS IS THE TYPE OF FLOW PATTERN THAT CAN BURY THEM BUT CLIMO ODDS AGAINST 6+ INCHES. WITH WWD BIAS OF NAM IN DEVELOPING SINGLE BAND...WILL ALSO HAVE TO KEEP AN EYE ON CASS, MI...ELKHART...AND KOSCIUSKO AS WELL. LAKE EFFECT WILL FINALLY CEASE ON THU AS H85 RIDGE BUILDS IN AND LL WINDS BEGIN TO BACK. AFTER A QUICK BREAK THU AFTERNOON...A CLIPPER WILL MOVE SE INTO THE AREA THU NIGHT INTO FRI. MODELS INDICATING WAA TO RESULT IN MIXED PRECIP BUT THINK BOUNDARY LAYER WILL BE KEPT JUST COOL ENOUGH BY SNOWPACK TO KEEP PRECIP IN THE FORM OF LIGHT SNOW OR LIGHT SLEET. TOO EARLY TO PIN DOWN ANY ACCUMS BUT EXPECT NO MORE THAN A FEW INCHES WITH THIS SYSTEM. BUMPED LOWS UP A TAD FRI MORNING WITH WAA APPEARING TO HAVE ENOUGH PUNCH TO KEEP LOWS SLIGHTLY WARMER EVEN WITH EXPECTED SNOWPACK. AGAIN STAYED CONSERVATIVE W/WARMUP THIS WEEKEND WITH SFC TEMPS ONLY INTO THE 40S THOUGH H85 WAA WILL TAKE PLACE IN EARNEST. THIS TREND ALSO BEING NOTICED IN MODELS WITH MEX NUMBERS NOW ONLY IN THE 30S ON SUNDAY. THOUGH ECMWF...CANADIAN...AND GFS ENSEMBLES INDICATING BEST FORCING FOR PRECIP TO HOLD OFF TO THE WEST...ADDED POPS SUNDAY TO FILL HOLE IN GRIDS. STG SYSTEM STILL LOOKS ON TRACK FOR EARLY TO MID NEXT WEEK WITH POSSIBLE IMPACTS RANGING FM HEAVY RAIN AND FLOODING TO SIGNIFICANT SNOWS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER STORM WARNING UNTIL 7 PM EST TUESDAY FOR INZ006>009-017- 018-025>027-032>034. LAKE EFFECT SNOW WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY AFTERNOON FOR INZ003-004. SNOW AND BLOWING SNOW ADVISORY UNTIL 4 PM EST /3 PM CST/ TUESDAY FOR INZ003-004. WINTER STORM WARNING UNTIL 4 PM EST /3 PM CST/ TUESDAY FOR INZ005-012>016-020-022>024. MI...WINTER STORM WARNING UNTIL 7 PM EST TUESDAY FOR MIZ080-081. LAKE EFFECT SNOW WATCH FROM LATE TUESDAY NIGHT THROUGH WEDNESDAY AFTERNOON FOR MIZ077. SNOW AND BLOWING SNOW ADVISORY UNTIL 4 PM EST TUESDAY FOR MIZ077>079. OH...WINTER STORM WARNING UNTIL 7 PM EST TUESDAY FOR OHZ001-002-004- 005-015-016-024-025. LM...GALE WARNING UNTIL 1 AM EST WEDNESDAY FOR LMZ043-046. && $$ SHORT TERM...MURPHY LONG TERM...SIMPSON AVIATION/UPDATE...SCHOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1240 AM EST MON FEB 25 2008 .AVIATION... LOW STRATUS DECK MOVING NORTH AND ENGULFING TAF SITES. SATELLITE SHOWS LOW CLOUDS EXPANDING ACROSS THE MIDWEST SO EXPECT LITTLE IMPROVEMENT. LOW LEVEL MOISTURE SUGGEST MVFR AND EVEN IFR VIS POSSIBLE SO LEFT THAT IN FORECAST. POTENT WINTER STORM APPROACHES LATE TODAY AND MORE SO TONIGHT. SHOULD SEE PCPN BEGIN LATE AFTERNOON WITH HEAVIER PCPN AND LOW VIS COMING TOWARD VERY END OF THIS TAF PERIOD AND MORE SO IN NEXT 6 HOURS BEYOND. HAVE TRENDED VIS AND CIG DOWN WITH RAIN AND SNOW MIX AT ONSET. SHOULD SEE CHANGE TO ALL SNOW NEAR 03Z AT KSBN AND NEAR OR AFTER 06Z AT KFWA. && .UPDATE... MADE A FEW ADJUSTMENTS TO THE SHORT TERM FORECAST...AND A TWEAK TO THE WINTER STORM WATCH AS PER REGIONAL COLLABORATION. IN THE SHORT TERM HAVE SIGNIFICANTLY INCREASED CLOUD COVER ACROSS THE REGION WITH STRATUS DECK CREEPING UP FROM THE SOUTH ACROSS THE REGION IN THE LIGHT SOUTHERLY FLOW. LIGHT SNOW PACK ACROSS AND JUST SOUTH OF THE SOUTHERN TIER OF COUNTIES IN OUR FORECAST AREA WILL ALLOW FOR A DECENT MOISTURE SOURCE TO PUSH MOIST AND SLIGHTLY WARMER AIR INTO THE REGION...FOR THIS REASON HAVE RAISED TEMPS A BIT AND ADDED MENTION OF AREAS OF FOG WITH PATCHY DENSE FOG POSSIBLE. LATEST RUC MODEL SHOWS A BETTER POSSIBILITY OF THIS ACROSS THE WESTERN TWO THIRDS OF THE REGION...MAINLY WEST OF A LINE FROM COLDWATER TO FORT WAYNE TO LIMA. RECENT MODEL TRENDS FROM THE 00Z/24 RUN TO THE 00Z/25 RUNS SHOWS INCREASING THREAT FOR WIDESPREAD WINTER STORM EVENT TO EXTEND ACROSS MUCH OF THE REGION...COLLABORATION WITH SURROUNDING OFFICE TONIGHT HAS LEAD TO THE ADDITION OF A FEW MORE COUNTIES IN THE WATCH...MAINLY IN THE SOUTHWESTERN PORTION OF THE FORECAST AREA IN WESTERN INDIANA...ALONG WITH THIS ADDITION ADDED A TIER OF COUNTIES TO THE SOUTH IN EASTERN INDIANA...INCLUDING ALLEN COUNTY INDIANA AND THE CITY OF FORT WAYNE...WITH THE MORNING RUSH HOUR TO BE IMPACTED TUESDAY MORNING...AND AT THE LOW END...WINTER ADVISORY CRITERIA MET...THOUGHT IT PRUDENT TO ADD AT THIS TIME ALONG WITH THE OTHER COUNTIES. CURRENT FORECAST AMOUNTS UNTOUCHED...WILL LET NIGHT SHIFT EVALUATE ANY CHANGE THERE...BUT ALL THE WATCH COUNTIES HAVE AT LEAST 4 INCHES FORECAST BY TUESDAY AFTN. STILL ANTICIPATING HEAVY BAND IN THE TROWAL THAT SHOULD BE PRESENT...AND WOULD MOST LIKELY BE PRESENT OVER THE FORECAST AREA LATE MONDAY NIGHT THROUGH TUESDAY MORNING...STRONG FRONTOGENETICAL FORCING FOUND THRU AT LEAST 15-18Z TUESDAY...WITH NEG EPV PRESENT IN TIME SERIES THRU 09-15Z ACROSS THE MUCH OF THE REGION. ALL UPDATED PRODUCTS OUT SHORTLY. && PREV DISCUSSION... /ISSUED 517 PM EST SUN FEB 24 2008/ SHORT TERM...TONIGHT AND MONDAY.... WEAK AND DAMPENING SHORTWAVE OVER ERN KY LAYING OUT SOME RESIDUAL MOISTURE ACRS SRN CWA AND LWR OHIO VALLEY THAT WILL SERVE AS SOURCE FOR STRATUS AS BL BECOMES MIXED OVERNIGHT WITH APPROACH OF 925MB JET AXIS. FAR WRN/NWRN ZONES MAY ALSO REACH LFC WITH SMALL/TRACE AMOUNTS OF FZDZ IN 25-30KT MIXED STRATUS DECK MONDAY AM. DROPPED TEMPS A FEW DEGREES TONIGHT WITH NON-DIURNAL TREND/EARLY MIN PRIOR TO STRATUS FORMATION THEN SLOW RISE. MAX TEMPS MON LOWERED SLIGHTLY ON EARLIER UPDATE ACCOUNTING FOR THICK ST COUNTERING WARM THERMAL ADVECTION AHEAD OF NEXT MAJOR SYSTEM. EXTREME SYSTEM TO COME TO FRUITION AS EPAC WAVE NOW ENTERING NRN CA PHASES BEAUTIFULLY WITH NRN STREAM SASK WAVE BEYOND F36. BY MONDAY EVENING THOUGH AS WEST COAST/MOISTURE LADEN WAVE ENTERS CENTRAL MSVLY...INITIAL WAVE OF I290K LIFT/3-4 G/KG MIDLVL MOISTURE TO PROVIDE AN INITIAL PASSING SHOT OF LIGHT RAFL AHEAD OF DEVELOPING WINTER STORM...RAISED POPS LATE MONDAY AFTN GIVEN MOISTURE/LIFT SIGNALS. LONG TERM...MONDAY NIGHT THROUGH SUNDAY... MAIN FOCUS ON POTENT UPR LOW MOVING INTO WRN US ATTM BREAKING DOWN WRN US RIDGING. EXPECT THIS S/W TO TRAVERSE ROCKIES AND PROMOTE LEE CYCLOGENESIS OVR NE CO LATER TODAY. THIS LOW WILL MOVE EAST TO CEN/SRN INDIANA BY 12Z TUE LEAVING CWA IN FAVORABLE AREA FOR ACCUMULATING SNOWS. BUMPED POPS UP MON NIGHT/TUE MORNING TO REFLECT FAIRLY STRONG MODEL AGREEMENT. GREAT COLLOCATION OF BEST OMEGA IN DGZ SHOULD PROMOTE PERIOD OF HEAVY SNOW EARLY TUE MORNING. THINKING NOW IS NORTH OF A KNOX/WARSAW/DEFIANCE LINE HAS BEST CHANCE FOR HEAVY SNOWS AS TEMP PROFILES S OF THIS LINE SUPPORT RAIN/SNOW EARLY FOLLOWED BY HIGH DENSITY SNOW THAT WILL BE TOUGH TO ACCUMULATE DUE TO COMPACTION, ETC. AS ALWAYS, EXACT TRACK OF LOW WILL HAVE GREAT IMPACT ON SNOWFALL TOTALS. HOISTED WINTER STORM WATCH FM 00Z TUE - 06Z WED. MODELS INDICATING MOST SYNOPTIC SNOW TO BE OVER BETWEEN 18Z AND 00Z IN THE WRN CWA...BUT LAST FEW RUNS HAVE BEEN SLIGHTLY SLOWER W/SYSTEM AND LE WORRIES JUSTIFY LATER EXPIRATION TIME. COBB ALGORITHM PRINTS OUT OVER A FOOT AT BOTH KSBN AND KFWA BUT IS COUNTERED BY AROUND 5 INCHES FROM COOK METHOD AND 6-8 GARCIA METHOD. OVERALL...4-8 INCHES OF SNOW LOOKS LIKELY IN WATCH AREA WITH INDICATIONS OF LOCALLY HIGHER AMOUNTS BEING POSSIBLE. THIS WILL NEED TO BE WATCHED AND POSSIBLY INCLUDED IN LATER UPGRADES. COLD AIR WL FILTER IN BEHIND SYSTEM WITH AFOREMENTIONED LE POSSIBILITIES AND AN APPARENT RETURN TO SINGLE DIGIT LOWS/LOW 20S HIGHS. TEMPS WILL WARM BACK INTO THE 30S THU AHEAD OF NEXT NW FLOW WAVE. THIS CLIPPER WL MOVE INTO THE AREA THU NIGHT BRINGING ANOTHER SHOT OF LIGHT SNOW. SOME CONCERN ENOUGH WARM AIR COULD CREEP INTO THE SRN CWA TO ALLOW SN TO MIX W/RA BUT MODELS NOT LIKELY ACCOUNTING FOR EXPECTED SNOWPACK AND ITS IMPACT ON SFC TEMPS SO WILL NOT INTRODUCE MIX WORDING ATTM. ANOTHER WAVE IN NW FLOW WILL SKIRT US FRI NITE...HOWEVER FORCING LOOKS TO BE FAIRLY WEAK AND NOT MUCH MOISTURE TO WORK WITH SO ELECTED TO LEAVE FRI NITE DRY. UPR LVL TROUGHING WILL DIG INTO THE ROCKIES BY SUNDAY WITH RESULTANT DOWNSTREAM RIDGING ALLOWING SW FLOW TO PUMP INTO AREA SUN INTO MON. ELECTED TO STAY FAIRLY CONSERVATIVE W/TEMPS GIVEN AFOREMENTIONED SNOW COVER AND DAY 7 TIMEFRAME. A QUICK PEEK PAST 7 DAYS HAS ECMWF AND GFS ENSEMBLES INDICATING YET ANOTHER POTENT SYSTEM TO BE WATCHED FOR NEXT WEEK. .PREV DISCUSSION... /ISSUED 624 PM EST SUN FEB 24 2008/ AVIATION (00Z TAFS)... MVFR OR VFR CONDITIONS ACROSS THE REGION...WITH THE TREND OVERNIGHT TOWARDS MVFR TO IFR CONDITIONS POSSIBLE. SOUTHERN HALF OF THE AREA UNDER CIGS AROUND 2.5 K FT...WITH SUFFICIENT LOW LEVEL MOISTURE AND TRAPPING INVERSION SOME STRATUS/FOG LOOKS TO DEVELOP OVERNIGHT WITH CIGS IN THE .6 TO 1K FT RANGE. THE LOW CIGS WILL LIKELY CONTINUE THROUGH THE MORNING AND LIFT SLIGHTLY TOWARDS AFTERNOON. VSBYS WILL LIKELY LINGER IN THE 4-6 SM RANGE. VERY LATE IN THE PERIOD (AFT 22Z) AS THE WINTER STORM APPROACHES A CHC FOR PRECIP WILL BEGIN...BIGGEST ISSUE HERE WILL BE HOW LONG IT TAKES TO MOISTEN THE LOWER LEVELS BEFORE IT STARTS TO REACH THE GROUND...WOULD BE MOSTLY SN NORTH WITH SNRA MIX POSSIBLE ACROSS THE SOUTH. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER STORM WATCH FROM MONDAY EVENING THROUGH LATE TUESDAY NIGHT FOR INZ003>009-012>018-020-022>024. MI...WINTER STORM WATCH FROM MONDAY EVENING THROUGH LATE TUESDAY NIGHT FOR MIZ077>081. OH...WINTER STORM WATCH FROM MONDAY EVENING THROUGH LATE TUESDAY NIGHT FOR OHZ001-002-004-005. LM...NONE. && $$ SHORT TERM...MURPHY LONG TERM...SIMPSON AVIATION/UPDATE...SCHOTT/LASHLEY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1033 PM EST SUN FEB 24 2008 .UPDATE... MADE A FEW ADJUSTMENTS TO THE SHORT TERM FORECAST...AND A TWEAK TO THE WINTER STORM WATCH AS PER REGIONAL COLLABORATION. IN THE SHORT TERM HAVE SIGNIFICANTLY INCREASED CLOUD COVER ACROSS THE REGION WITH STRATUS DECK CREEPING UP FROM THE SOUTH ACROSS THE REGION IN THE LIGHT SOUTHERLY FLOW. LIGHT SNOW PACK ACROSS AND JUST SOUTH OF THE SOUTHERN TIER OF COUNTIES IN OUR FORECAST AREA WILL ALLOW FOR A DECENT MOISTURE SOURCE TO PUSH MOIST AND SLIGHTLY WARMER AIR INTO THE REGION...FOR THIS REASON HAVE RAISED TEMPS A BIT AND ADDED MENTION OF AREAS OF FOG WITH PATCHY DENSE FOG POSSIBLE. LATEST RUC MODEL SHOWS A BETTER POSSIBILITY OF THIS ACROSS THE WESTERN TWO THIRDS OF THE REGION...MAINLY WEST OF A LINE FROM COLDWATER TO FORT WAYNE TO LIMA. RECENT MODEL TRENDS FROM THE 00Z/24 RUN TO THE 00Z/25 RUNS SHOWS INCREASING THREAT FOR WIDESPREAD WINTER STORM EVENT TO EXTEND ACROSS MUCH OF THE REGION...COLLABORATION WITH SURROUNDING OFFICE TONIGHT HAS LEAD TO THE ADDITION OF A FEW MORE COUNTIES IN THE WATCH...MAINLY IN THE SOUTHWESTERN PORTION OF THE FORECAST AREA IN WESTERN INDIANA...ALONG WITH THIS ADDITION ADDED A TIER OF COUNTIES TO THE SOUTH IN EASTERN INDIANA...INCLUDING ALLEN COUNTY INDIANA AND THE CITY OF FORT WAYNE...WITH THE MORNING RUSH HOUR TO BE IMPACTED TUESDAY MORNING...AND AT THE LOW END...WINTER ADVISORY CRITERIA MET...THOUGHT IT PRUDENT TO ADD AT THIS TIME ALONG WITH THE OTHER COUNTIES. CURRENT FORECAST AMOUNTS UNTOUCHED...WILL LET NIGHT SHIFT EVALUATE ANY CHANGE THERE...BUT ALL THE WATCH COUNTIES HAVE AT LEAST 4 INCHES FORECAST BY TUESDAY AFTN. STILL ANTICIPATING HEAVY BAND IN THE TROWAL THAT SHOULD BE PRESENT...AND WOULD MOST LIKELY BE PRESENT OVER THE FORECAST AREA LATE MONDAY NIGHT THROUGH TUESDAY MORNING...STRONG FRONTOGENETICAL FORCING FOUND THRU AT LEAST 15-18Z TUESDAY...WITH NEG EPV PRESENT IN TIME SERIES THRU 09-15Z ACROSS THE MUCH OF THE REGION. ALL UPDATED PRODUCTS OUT SHORTLY. && PREV DISCUSSION... /ISSUED 517 PM EST SUN FEB 24 2008/ SHORT TERM...TONIGHT AND MONDAY.... WEAK AND DAMPENING SHORTWAVE OVER ERN KY LAYING OUT SOME RESIDUAL MOISTURE ACRS SRN CWA AND LWR OHIO VALLEY THAT WILL SERVE AS SOURCE FOR STRATUS AS BL BECOMES MIXED OVERNIGHT WITH APPROACH OF 925MB JET AXIS. FAR WRN/NWRN ZONES MAY ALSO REACH LFC WITH SMALL/TRACE AMOUNTS OF FZDZ IN 25-30KT MIXED STRATUS DECK MONDAY AM. DROPPED TEMPS A FEW DEGREES TONIGHT WITH NON-DIURNAL TREND/EARLY MIN PRIOR TO STRATUS FORMATION THEN SLOW RISE. MAX TEMPS MON LOWERED SLIGHTLY ON EARLIER UPDATE ACCOUNTING FOR THICK ST COUNTERING WARM THERMAL ADVECTION AHEAD OF NEXT MAJOR SYSTEM. EXTREME SYSTEM TO COME TO FRUITION AS EPAC WAVE NOW ENTERING NRN CA PHASES BEAUTIFULLY WITH NRN STREAM SASK WAVE BEYOND F36. BY MONDAY EVENING THOUGH AS WEST COAST/MOISTURE LADEN WAVE ENTERS CENTRAL MSVLY...INITIAL WAVE OF I290K LIFT/3-4 G/KG MIDLVL MOISTURE TO PROVIDE AN INITIAL PASSING SHOT OF LIGHT RAFL AHEAD OF DEVELOPING WINTER STORM...RAISED POPS LATE MONDAY AFTN GIVEN MOISTURE/LIFT SIGNALS. LONG TERM...MONDAY NIGHT THROUGH SUNDAY... MAIN FOCUS ON POTENT UPR LOW MOVING INTO WRN US ATTM BREAKING DOWN WRN US RIDGING. EXPECT THIS S/W TO TRAVERSE ROCKIES AND PROMOTE LEE CYCLOGENESIS OVR NE CO LATER TODAY. THIS LOW WILL MOVE EAST TO CEN/SRN INDIANA BY 12Z TUE LEAVING CWA IN FAVORABLE AREA FOR ACCUMULATING SNOWS. BUMPED POPS UP MON NIGHT/TUE MORNING TO REFLECT FAIRLY STRONG MODEL AGREEMENT. GREAT COLLOCATION OF BEST OMEGA IN DGZ SHOULD PROMOTE PERIOD OF HEAVY SNOW EARLY TUE MORNING. THINKING NOW IS NORTH OF A KNOX/WARSAW/DEFIANCE LINE HAS BEST CHANCE FOR HEAVY SNOWS AS TEMP PROFILES S OF THIS LINE SUPPORT RAIN/SNOW EARLY FOLLOWED BY HIGH DENSITY SNOW THAT WILL BE TOUGH TO ACCUMULATE DUE TO COMPACTION, ETC. AS ALWAYS, EXACT TRACK OF LOW WILL HAVE GREAT IMPACT ON SNOWFALL TOTALS. HOISTED WINTER STORM WATCH FM 00Z TUE - 06Z WED. MODELS INDICATING MOST SYNOPTIC SNOW TO BE OVER BETWEEN 18Z AND 00Z IN THE WRN CWA...BUT LAST FEW RUNS HAVE BEEN SLIGHTLY SLOWER W/SYSTEM AND LE WORRIES JUSTIFY LATER EXPIRATION TIME. COBB ALGORITHM PRINTS OUT OVER A FOOT AT BOTH KSBN AND KFWA BUT IS COUNTERED BY AROUND 5 INCHES FROM COOK METHOD AND 6-8 GARCIA METHOD. OVERALL...4-8 INCHES OF SNOW LOOKS LIKELY IN WATCH AREA WITH INDICATIONS OF LOCALLY HIGHER AMOUNTS BEING POSSIBLE. THIS WILL NEED TO BE WATCHED AND POSSIBLY INCLUDED IN LATER UPGRADES. COLD AIR WL FILTER IN BEHIND SYSTEM WITH AFOREMENTIONED LE POSSIBILITIES AND AN APPARENT RETURN TO SINGLE DIGIT LOWS/LOW 20S HIGHS. TEMPS WILL WARM BACK INTO THE 30S THU AHEAD OF NEXT NW FLOW WAVE. THIS CLIPPER WL MOVE INTO THE AREA THU NIGHT BRINGING ANOTHER SHOT OF LIGHT SNOW. SOME CONCERN ENOUGH WARM AIR COULD CREEP INTO THE SRN CWA TO ALLOW SN TO MIX W/RA BUT MODELS NOT LIKELY ACCOUNTING FOR EXPECTED SNOWPACK AND ITS IMPACT ON SFC TEMPS SO WILL NOT INTRODUCE MIX WORDING ATTM. ANOTHER WAVE IN NW FLOW WILL SKIRT US FRI NITE...HOWEVER FORCING LOOKS TO BE FAIRLY WEAK AND NOT MUCH MOISTURE TO WORK WITH SO ELECTED TO LEAVE FRI NITE DRY. UPR LVL TROUGHING WILL DIG INTO THE ROCKIES BY SUNDAY WITH RESULTANT DOWNSTREAM RIDGING ALLOWING SW FLOW TO PUMP INTO AREA SUN INTO MON. ELECTED TO STAY FAIRLY CONSERVATIVE W/TEMPS GIVEN AFOREMENTIONED SNOW COVER AND DAY 7 TIMEFRAME. A QUICK PEEK PAST 7 DAYS HAS ECMWF AND GFS ENSEMBLES INDICATING YET ANOTHER POTENT SYSTEM TO BE WATCHED FOR NEXT WEEK. .PREV DISCUSSION... /ISSUED 624 PM EST SUN FEB 24 2008/ AVIATION (00Z TAFS)... MVFR OR VFR CONDITIONS ACROSS THE REGION...WITH THE TREND OVERNIGHT TOWARDS MVFR TO IFR CONDITIONS POSSIBLE. SOUTHERN HALF OF THE AREA UNDER CIGS AROUND 2.5 K FT...WITH SUFFICIENT LOW LEVEL MOISTURE AND TRAPPING INVERSION SOME STRATUS/FOG LOOKS TO DEVELOP OVERNIGHT WITH CIGS IN THE .6 TO 1K FT RANGE. THE LOW CIGS WILL LIKELY CONTINUE THROUGH THE MORNING AND LIFT SLIGHTLY TOWARDS AFTERNOON. VSBYS WILL LIKELY LINGER IN THE 4-6 SM RANGE. VERY LATE IN THE PERIOD (AFT 22Z) AS THE WINTER STORM APPROACHES A CHC FOR PRECIP WILL BEGIN...BIGGEST ISSUE HERE WILL BE HOW LONG IT TAKES TO MOISTEN THE LOWER LEVELS BEFORE IT STARTS TO REACH THE GROUND...WOULD BE MOSTLY SN NORTH WITH SNRA MIX POSSIBLE ACROSS THE SOUTH. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER STORM WATCH FROM MONDAY EVENING THROUGH LATE TUESDAY NIGHT FOR INZ003>009-012>018-020-022>024. MI...WINTER STORM WATCH FROM MONDAY EVENING THROUGH LATE TUESDAY NIGHT FOR MIZ077>081. OH...WINTER STORM WATCH FROM MONDAY EVENING THROUGH LATE TUESDAY NIGHT FOR OHZ001-002-004-005. LM...NONE. && $$ SHORT TERM...MURPHY LONG TERM...SIMPSON AVIATION/UPDATE...SCHOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 1150 AM EST SUN FEB 24 2008 .AVIATION...DISCUSSION FOR 18Z TAFS IFR CONDS WILL CONTINUE INTO THE AFTERNOON AT BMG AS SNOW GRADUALLY ENDS. MVFR VIS/CIGS WILL THEN PREVAIL AS A SLOW CLEARING TREND TAKES PLACE THROUGH 06Z. CIGS MAY BECOME UNRESTRICTED AT LAF/HUF FOR A TIME TONIGHT AND THIS COULD LEAD TO IFR VIS CONDS GIVEN THE WET GROUND AND CONDS PRESENT SUN MORNING. SFC WINDS WILL BECOME SSW AT 5 TO 10KTS WHICH COULD FAVOR STRATUS OVER FOG. AT THIS TIME...SEE A SCENARIO THAT INCLUDES SOME CLEARING AND A RISK OF IFR VIS AFTER 06Z. WEAK ISENTROPIC LIFT IN THE 285-295K (LOWEST 3KFT) MAY ALSO ACT TO SATURATE THE MIXING LAYER BELOW THE DEVELOPING INVERSION TONIGHT. THIS COULD SET THE STAGE FOR THE RE-DEVELOPMENT OF A STRATUS DECK ESPECIALLY TOWARD 12Z MON. && .DISCUSSION... FORECAST FOCUS IS ON CHANCES FOR PRECIP TODAY AND THEN AGAIN MON-WED. AT 08Z A WEAKENING UPPER WAVE WAS ACROSS MO AND MOVING E. AREA OF -SN WAS ACROSS MO INTO FAR SWRN IN. AT THE SFC...HIGH PRESSURE WAS ACROSS THE FORECAST AREA /FA/. MOST MODELS IN DECENT AGREEMENT...BUT OPERATIONAL NAM STILL LOOKS TOO FAR N WITH SFC LOW MON NIGHT. GFS/ECMWF/CANADIAN/PARALLEL NAM ARE ALL FARTHER SOUTH. WILL CONTINUE TO GO WITH CONSENSUS. NATIONAL RADAR MOSAIC SHOWING AREA OF PRECIP ASSOCIATED WITH UPPER WAVE ALREADY BEGINNING A SLOW WEAKENING TREND. HOWEVER...STILL A GOOD AMOUNT OF PRECIP OUT THERE. ALTHOUGH AIR IS DRIER ACROSS THE FA THAN ACROSS MO...STILL LOOKS LIKE THAT SOME PRECIP MIGHT MAKE IT INTO THE SWRN FA THIS MORNING. 06Z NAM/RUC BACKS THIS IDEA UP. THUS WILL ADD CHANCE POPS TO FAR SRN FA THRU 18Z...WITH SLIGHT CHC POPS JUST TO THE N. BELIEVE WEAKENING SYSTEM COMBINED WITH DRIER AIR SHOULD KEEP REMAINDER OF SRN HALF OF FA DRY. NRN FA STARTED OUT QUITE COLD THIS MORNING AS LIGHT WINDS AND SNOW COVER ALLOWED GOOD RADIATIONAL COOLING. MOS DID NOT CATCH THIS WELL SO WILL CUT MOS HIGHS ACROSS AREAS WITH SNOW. ELSEWHERE CLOUDS WILL KEEP TEMPS A LITTLE COOLER THAN PREV EXPECTED...AND A BLEND OF MET/MAV REFLECTS THIS WELL. DRY CONDITIONS WILL PERSIST TONIGHT AS NEXT SYSTEM GETS ORGANIZED WELL TO OUR W. MET/MAV LOW TEMPS LOOK REASONABLE FOR PARTLY CLOUDY CONDITIONS. AS THE LOW APPROACHES THE FA ON MONDAY...MOISTURE WILL INCREASE ACROSS THE FA. STILL LOOKS LIKE BEST LIFT DOES NOT ARRIVE UNTIL AFT 00Z. POPS ARE ALREADY IN FORECAST AND DO NOT WANT TO FLIP-FLOP...SO KEPT LOW POPS IN FOR THE AFTN. AS THE LOW MOVES ACROSS THE STATE ON MON NIGHT...DECENT FORCING WILL OCCUR /AS CAN BE SEEN IN QVECTOR PROGS/. WILL CONTINUE LIKELY POPS ALL AREAS. COLDER AIR WILL WORK IN BEHIND THE LOW OVERNIGHT AND SHOULD BEGIN TO CHANGE PTYPE TO SNOW IN THE WRN FA. ON TUE ALL MODELS SHOWING OR HINTING AT A DEFORMATION ZONE SETTING UP ACROSS FA. CONTINUED HIGH CHANCE TO LIKELY POPS. WITH COLDER AIR MOVING IN...THERE COULD BE A FEW INCHES OF SNOW SOMEWHERE IN THE FA. CHANCES FOR SNOW WILL GRADUALLY DECREASE TUE NIGHT/WED FROM W TO E AS SYSTEM PULLS EAST. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AVIATION...CO PUBLIC...CS in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 625 AM EST SUN FEB 24 2008 .AVIATION...DISCUSSION FOR 12Z TAFS MVFR SC DECK STARTING TO FROM AND SHOULD REMAIN IN PLACE THROUGH THE TAF PD BASED ON LOW LVL MOISTURE PROGS AND MODEL TIME SECS. ALSO...AREA OF SN EXPECTED TO SPREAD ACRS HUF AND BMG THIS MRNG BASED ON RADAR TRENDS AND QPF PROGS. VBSYS ALSO MAINLY MVFR THROUGH THE MRNG THERE. && .DISCUSSION... FORECAST FOCUS IS ON CHANCES FOR PRECIP TODAY AND THEN AGAIN MON-WED. AT 08Z A WEAKENING UPPER WAVE WAS ACROSS MO AND MOVING E. AREA OF -SN WAS ACROSS MO INTO FAR SWRN IN. AT THE SFC...HIGH PRESSURE WAS ACROSS THE FORECAST AREA /FA/. MOST MODELS IN DECENT AGREEMENT...BUT OPERATIONAL NAM STILL LOOKS TOO FAR N WITH SFC LOW MON NIGHT. GFS/ECMWF/CANADIAN/PARALLEL NAM ARE ALL FARTHER SOUTH. WILL CONTINUE TO GO WITH CONSENSUS. NATIONAL RADAR MOSAIC SHOWING AREA OF PRECIP ASSOCIATED WITH UPPER WAVE ALREADY BEGINNING A SLOW WEAKENING TREND. HOWEVER...STILL A GOOD AMOUNT OF PRECIP OUT THERE. ALTHOUGH AIR IS DRIER ACROSS THE FA THAN ACROSS MO...STILL LOOKS LIKE THAT SOME PRECIP MIGHT MAKE IT INTO THE SWRN FA THIS MORNING. 06Z NAM/RUC BACKS THIS IDEA UP. THUS WILL ADD CHANCE POPS TO FAR SRN FA THRU 18Z...WITH SLIGHT CHC POPS JUST TO THE N. BELIEVE WEAKENING SYSTEM COMBINED WITH DRIER AIR SHOULD KEEP REMAINDER OF SRN HALF OF FA DRY. NRN FA STARTED OUT QUITE COLD THIS MORNING AS LIGHT WINDS AND SNOW COVER ALLOWED GOOD RADIATIONAL COOLING. MOS DID NOT CATCH THIS WELL SO WILL CUT MOS HIGHS ACROSS AREAS WITH SNOW. ELSEWHERE CLOUDS WILL KEEP TEMPS A LITTLE COOLER THAN PREV EXPECTED...AND A BLEND OF MET/MAV REFLECTS THIS WELL. DRY CONDITIONS WILL PERSIST TONIGHT AS NEXT SYSTEM GETS ORGANIZED WELL TO OUR W. MET/MAV LOW TEMPS LOOK REASONABLE FOR PARTLY CLOUDY CONDITIONS. AS THE LOW APPROACHES THE FA ON MONDAY...MOISTURE WILL INCREASE ACROSS THE FA. STILL LOOKS LIKE BEST LIFT DOES NOT ARRIVE UNTIL AFT 00Z. POPS ARE ALREADY IN FORECAST AND DO NOT WANT TO FLIP-FLOP...SO KEPT LOW POPS IN FOR THE AFTN. AS THE LOW MOVES ACROSS THE STATE ON MON NIGHT...DECENT FORCING WILL OCCUR /AS CAN BE SEEN IN QVECTOR PROGS/. WILL CONTINUE LIKELY POPS ALL AREAS. COLDER AIR WILL WORK IN BEHIND THE LOW OVERNIGHT AND SHOULD BEGIN TO CHANGE PTYPE TO SNOW IN THE WRN FA. ON TUE ALL MODELS SHOWING OR HINTING AT A DEFORMATION ZONE SETTING UP ACROSS FA. CONTINUED HIGH CHANCE TO LIKELY POPS. WITH COLDER AIR MOVING IN...THERE COULD BE A FEW INCHES OF SNOW SOMEWHERE IN THE FA. CHANCES FOR SNOW WILL GRADUALLY DECREASE TUE NIGHT/WED FROM W TO E AS SYSTEM PULLS EAST. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AVIATION...MK PUBLIC...CS in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 320 AM EST SUN FEB 24 2008 .DISCUSSION... FORECAST FOCUS IS ON CHANCES FOR PRECIP TODAY AND THEN AGAIN MON-WED. AT 08Z A WEAKENING UPPER WAVE WAS ACROSS MO AND MOVING E. AREA OF -SN WAS ACROSS MO INTO FAR SWRN IN. AT THE SFC...HIGH PRESSURE WAS ACROSS THE FORECAST AREA /FA/. MOST MODELS IN DECENT AGREEMENT...BUT OPERATIONAL NAM STILL LOOKS TOO FAR N WITH SFC LOW MON NIGHT. GFS/ECMWF/CANADIAN/PARALLEL NAM ARE ALL FARTHER SOUTH. WILL CONTINUE TO GO WITH CONSENSUS. NATIONAL RADAR MOSAIC SHOWING AREA OF PRECIP ASSOCIATED WITH UPPER WAVE ALREADY BEGINNING A SLOW WEAKENING TREND. HOWEVER...STILL A GOOD AMOUNT OF PRECIP OUT THERE. ALTHOUGH AIR IS DRIER ACROSS THE FA THAN ACROSS MO...STILL LOOKS LIKE THAT SOME PRECIP MIGHT MAKE IT INTO THE SWRN FA THIS MORNING. 06Z NAM/RUC BACKS THIS IDEA UP. THUS WILL ADD CHANCE POPS TO FAR SRN FA THRU 18Z...WITH SLIGHT CHC POPS JUST TO THE N. BELIEVE WEAKENING SYSTEM COMBINED WITH DRIER AIR SHOULD KEEP REMAINDER OF SRN HALF OF FA DRY. NRN FA STARTED OUT QUITE COLD THIS MORNING AS LIGHT WINDS AND SNOW COVER ALLOWED GOOD RADIATIONAL COOLING. MOS DID NOT CATCH THIS WELL SO WILL CUT MOS HIGHS ACROSS AREAS WITH SNOW. ELSEWHERE CLOUDS WILL KEEP TEMPS A LITTLE COOLER THAN PREV EXPECTED...AND A BLEND OF MET/MAV REFLECTS THIS WELL. DRY CONDITIONS WILL PERSIST TONIGHT AS NEXT SYSTEM GETS ORGANIZED WELL TO OUR W. MET/MAV LOW TEMPS LOOK REASONABLE FOR PARTLY CLOUDY CONDITIONS. AS THE LOW APPROACHES THE FA ON MONDAY...MOISTURE WILL INCREASE ACROSS THE FA. STILL LOOKS LIKE BEST LIFT DOES NOT ARRIVE UNTIL AFT 00Z. POPS ARE ALREADY IN FORECAST AND DO NOT WANT TO FLIP-FLOP...SO KEPT LOW POPS IN FOR THE AFTN. AS THE LOW MOVES ACROSS THE STATE ON MON NIGHT...DECENT FORCING WILL OCCUR /AS CAN BE SEEN IN QVECTOR PROGS/. WILL CONTINUE LIKELY POPS ALL AREAS. COLDER AIR WILL WORK IN BEHIND THE LOW OVERNIGHT AND SHOULD BEGIN TO CHANGE PTYPE TO SNOW IN THE WRN FA. ON TUE ALL MODELS SHOWING OR HINTING AT A DEFORMATION ZONE SETTING UP ACROSS FA. CONTINUED HIGH CHANCE TO LIKELY POPS. WITH COLDER AIR MOVING IN...THERE COULD BE A FEW INCHES OF SNOW SOMEWHERE IN THE FA. CHANCES FOR SNOW WILL GRADUALLY DECREASE TUE NIGHT/WED FROM W TO E AS SYSTEM PULLS EAST. && .AVIATION...DISCUSSION FOR 06Z TAFS HIGH PRESSURE WILL SLOWLY CROSS THE AREA WEST TO EAST THROUGH FORCAST PERIOD. AT THE SAME TIME WEAK LOW PRESSURE WILL PASS TO THE SOUTH OF THE AREA. CIGS MOSTLY AOA 35 HUNDRED FEET FOR THE PERIOD. AREAS OF MVFR CIGS SOUTH OF INDIANAPOLIS BECAUSE OF PROXIMITY OF LOW. MOST VSBYS VFR...BUT AREAS OF MVFR VSBYS IN FOG TONIGHT INTO MIDNIGHT SUNDAY. CLOUDS WILL REDUCE FOG DENSITY OVERNIGHT BUT ALSO DELAY ITS DISSIPITATION SUNDAY. WINDS LIGHT AND VRBL OVERNIGHT AS HIGH CROSSES AREA. WINDS BECOMING SOUTH LESS THAN 10 KTS SUNDAY. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AVIATION...JK PUBLIC...CS in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 925 PM CST MON FEB 25 2008 .UPDATE TO FORECAST AND AVIATION DISCUSSION... SNOW TAPERING OFF ACROSS MUCH OF THE NORTHERN HALF OF THE CWA...AS SFC LOW SLIDES EAST SOUTHEAST FROM EASTERN MISSOURI TO WESTERN KENTUCKY LATE TONIGHT...AND DRIER AIR SINKING SOUTHWARD FROM THE NORTHERN PLAINS. AREA OF CLEARING PUSHING SOUTH ACROSS ERN SD/WRN MN EXPECTED TO PUSH THROUGH THE NORTHERN/CENTRAL CWA OVERNIGHT. ALSO SEEING TEMPS FALL FASTER THAN EXPECTED IN CLEARING AREA...SO HAVE LOWERED MIN TEMPS ACROSS NORTHWESTERN PORTION OF CWA. ALSO WITH SYSTEM SLIDING EASTWARD...AND PRECIP TAPERING OFF EXPECT MUCH OF THE PRECIP TO COME TO AN END BY MIDNIGHT...WITH ONLY A SMALL AMOUNT LINGERING PAST MIDNIGHT NEAR OTTUMWA/BLOOMFIELD AREAS. HAVE MINIMIZED AREAL EXTENT OF THE WINTER WEATHER ADVISORY TO SOUTHEASTERN THIRD OF THE CWA...WHERE SNOW REMAINS ACROSS THE AREA. BLOWING SNOW THREAT SEEMS TO BE MINIMIZED DUE TO THE SNOW BEING HEAVY AND WET. .PREVIOUS DISCUSSION... ONGOING WINTER WEATHER IS THE MAIN FOCUS THIS FORECAST PACKAGE. CURRENT AXIS OF HEAVIEST PRECIPITATION EXTENDS FROM NEAR ATLANTIC...THROUGH AMES...TO WATERLOO. OVERALL...NORTHWARD PUSH OF WARMER AIR HAS BEEN STRONGER THAN EXPECTED TODAY...AND THIS HAS RESULTED IN A LATER CHANGE OVER TO SNOW. MANY ROADS NORTH AND EAST OF THE DES MOINES AREA ON PARTLY TO MOSTLY SNOW COVERED...WITH MAINLY WET ROADS SOUTH AND EAST OF DES MOINES. AS COLDER AIR FROM THE NORTHWEST CONTINUES TO ERODE THE WARM NOSE ALOFT...PRECIPITATION WILL CHANGE OVER TO ALL SNOW ACROSS THE REMAINDER OF THE FORECAST AREA THROUGH THE LATE AFTERNOON AND EARLY EVENING. THE RUC FN VECTOR CONVERGENCE IN THE 600-500MB LAYER HAS BEEN MODELING THE BAND WELL TODAY...AND IS PROGGED TO CONTINUE SLIDING SOUTHEAST THROUGH THIS EVENING. A FEW LOCATIONS NORTH AND WEST OF DES MOINES HAVE RECEIVED 1 TO 2 INCHES OF SNOW SO FAR...BUT THE SNOW WILL BE ENDING RELATIVELY QUICKLY OVER THE NEXT SEVERAL HOURS. ADDITIONAL SNOW NEAR AND SE OF DES MOINES IS ALSO EXPECTED TO BE RATHER LIMITED BY THE LATE TRANSITION...AND SHOULD BE DIMINISHED TO VERY LIGHT SNOW OR FLURRIES BETWEEN 9 PM AND MIDNIGHT TONIGHT. STORM TOTAL SNOWFALL AMOUNTS IN THE 3 TO 5 INCH RANGE ARE EXPECTED THROUGH TONIGHT...SO HAVE OPTED TO DOWNGRADE THE WINTER STORM WARNING TO A WINTER WEATHER ADVISORY. OTHER CHANGES WERE TO TRIM HEADLINES OVER NW/W COUNTIES...AND EXPAND THE ADVISORY TO INCLUDE SOUTH CENTRAL AND SE COUNTIES. THE ADVISORY WILL ALSO EXPIRE AT MIDNIGHT...RATHER THAN CONTINUE THROUGH THE OVERNIGHT HOURS. WINDS WILL INCREASE THIS EVENING...WITH SUSTAINED SPEEDS IN THE 15 TO 25 MPH RANGE AND GUSTS AROUND 35 MPH OR SO. THE WINDS SHOULD LAG SLIGHTLY BEHIND THE HIGHER INTENSITY SNOW. ALSO...DUE TO THE HEAVY NATURE OF THE SNOW...AND VISIBILITY TRENDS THIS AFTERNOON...DON/T BELIEVE BLOWING SNOW WILL BE MUCH OF A PROBLEM IN TERMS OF VISIBILITY. WILL KEEP A MENTION OF PATCHY BLSN...BUT THE MAIN IMPACT SHOULD BE SHALLOW DRIFTING OVER ROADS. LIGHT SNOW OR FLURRIES WILL LINGER TUESDAY...OTHERWISE EXPECT ANOTHER SHOT OF COLDER AIR INTO WEDNESDAY. A CLIPPER SYSTEM WILL ARRIVE THURSDAY...AND WILL LIKELY HAVE THE HIGHEST IMPACT OVER THE NORTHEAST HALF OF IOWA WITH LIGHT TO POSSIBLY MODERATE ACCUMULATIONS. UPPER FLOW WILL THEN TRANSITION TO ZONAL FLOW WITH WARMING TEMPS THROUGH THE WEEKEND. THE NEXT CHANCE OF PRECIP WILL COME SUNDAY INTO MONDAY. .AVIATION...26/00Z SNOW TAPERING OFF ACROSS THE SOUTHERN TAF SITES...EXPECT SNOW TO END WITHIN THE NEXT HALF HOUR AT KDSM...AND WITHIN THE NEXT FEW HOURS AT KOTM. WHERE SNOW IF FALLING ACROSS SOUTHEASTERN THIRD OF CWA...EXPECT LIFR CONDITIONS DUE TO LOW VSBYS/CIGS IN THE SNOW. MVFR CEILINGS/VSBYS EXPECTED ELSEWHERE THROUGH MUCH OF THE NIGHT...ESPECIALLY KALO. KMCW/KFOD MAY SEE SOME VFR CONDITIONS TOWARD LATE TONIGHT/EARLY MORNING HOURS AS CLEARING AREA ACROSS ERN SD/WRN MN MAKES ITS WAY SOUTHEASTWARD OVERNIGHT. OTHERWISE CIGS TO RETURN TUESDAY...AS ANOTHER SHORTWAVE DROPS THROUGH THE AREA BRINGING SCATTERED FLURRIES. && .DMX WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR APPANOOSE-CLARKE-DAVIS-DECATUR-JASPER-LUCAS-MADISON- MAHASKA-MARION-MONROE-POWESHIEK-TAMA-UNION-WAPELLO-WARREN-WAYNE. && $$ PUBLIC...KINNEY/MOYER UPDATE/AVIATION...ALBRECHT ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 926 PM CST MON FEB 25 2008 .UPDATE... THE WINTER STORM WARNING HAS BEEN CHANGED TO A SNOW AND BLOWING SNOW ADVISORY FOR MOST OF THE AREA. THE WARNING REMAINS IN EFFECT FOR WHITESIDE...HENRY...BUREAU AND PUTNAM COUNTIES. SNOWFALL TOTALS SO FAR HAVE BEEN UP TO 3 INCHES EXPECT FOR A FEW 4 INCH REPORTS IN NW IL. RADAR TRENDS THE LAST COUPLE OF HOURS HAS SHOWN THE HIGHER REFLECTIVITY/S DIMINISHING AS WELL AS IR IMAGES SHOWING CLOUD TOPS WARMING OVER ERN IA AND NW IL ALL SUGGESTING THAT THE BEST FORCING HAS ALREADY MOVED THROUGH THE AREA. THIS IS ALSO SUPPORTED BY THE NAM/RUC SHOWING THE BEST FRONTOGENESIS AS WELL AS SYNOPTIC LIFT MOVING THROUGH THE AREA EARLY THIS EVENING. WITH THE TRENDS AND MODEL DATA SUGGESTING THE SNOWFALL EVENT IS WINDING DOWN HAVE DROPPED THE WINTER STORM WARNING BACK TO AN ADVISORY WITH TOTAL AMOUNTS OF 2 TO 5 INCHES. THE WARNING WAS KEPT IN PLACE FOR A FEW COUNTIES EAST OF THE RIVER WHERE SOME 4 INCH AMOUNTS HAVE BEEN REPORTED. ALSO A BAND OF STRONGER REFLECTIVITY/S EXTENDING EAST FROM KMLI WILL PRODUCE HEAVY SNOW FOR A WHILE THE REST OF THIS EVENING. THIS BAND OF HEAVIER SNOW SHOULD MOVE OUT OF THE AREA BY MIDNIGHT. NW WINDS CURRENTLY GUSTING OVER 40 MPH IN WRN IA SHOULD SPREAD E THROUGH THE MS VALLEY TONIGHT PRODUCING WIDESPREAD BLOWING AND DRIFTING TUESDAY MORNING. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...SNOW AND BLOWING SNOW ADVISORY UNTIL 12 PM CST TUESDAY FOR BENTON-BUCHANAN-CEDAR-CLINTON-DELAWARE-DES MOINES-DUBUQUE- HENRY IA-IOWA-JACKSON-JEFFERSON-JOHNSON-JONES-KEOKUK-LEE- LINN-LOUISA-MUSCATINE-SCOTT-VAN BUREN-WASHINGTON. IL...SNOW AND BLOWING SNOW ADVISORY UNTIL 12 PM CST TUESDAY FOR CARROLL-HANCOCK-HENDERSON-JO DAVIESS-MCDONOUGH-MERCER-ROCK ISLAND-STEPHENSON-WARREN. WINTER STORM WARNING UNTIL 12 PM CST TUESDAY FOR BUREAU-HENRY IL- PUTNAM-WHITESIDE. MO...SNOW AND BLOWING SNOW ADVISORY UNTIL 12 PM CST TUESDAY FOR CLARK- SCOTLAND. && $$ DLF ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 315 PM CST MON FEB 25 2008 .DISCUSSION... ONGOING WINTER WEATHER IS THE MAIN FOCUS THIS FORECAST PACKAGE. CURRENT AXIS OF HEAVIEST PRECIPITATION EXTENDS FROM NEAR ATLANTIC...THROUGH AMES...TO WATERLOO. OVERALL...NORTHWARD PUSH OF WARMER AIR HAS BEEN STRONGER THAN EXPECTED TODAY...AND THIS HAS RESULTED IN A LATER CHANGE OVER TO SNOW. MANY ROADS NORTH AND EAST OF THE DES MOINES AREA ON PARTLY TO MOSTLY SNOW COVERED...WITH MAINLY WET ROADS SOUTH AND EAST OF DES MOINES. AS COLDER AIR FROM THE NORTHWEST CONTINUES TO ERODE THE WARM NOSE ALOFT...PRECIPITATION WILL CHANGE OVER TO ALL SNOW ACROSS THE REMAINDER OF THE FORECAST AREA THROUGH THE LATE AFTERNOON AND EARLY EVENING. THE RUC FN VECTOR CONVERGENCE IN THE 600-500MB LAYER HAS BEEN MODELING THE BAND WELL TODAY...AND IS PROGGED TO CONTINUE SLIDING SOUTHEAST THROUGH THIS EVENING. A FEW LOCATIONS NORTH AND WEST OF DES MOINES HAVE RECEIVED 1 TO 2 INCHES OF SNOW SO FAR...BUT THE SNOW WILL BE ENDING RELATIVELY QUICKLY OVER THE NEXT SEVERAL HOURS. ADDITIONAL SNOW NEAR AND SE OF DES MOINES IS ALSO EXPECTED TO BE RATHER LIMITED BY THE LATE TRANSITION...AND SHOULD BE DIMINISHED TO VERY LIGHT SNOW OR FLURRIES BETWEEN 9 PM AND MIDNIGHT TONIGHT. STORM TOTAL SNOWFALL AMOUNTS IN THE 3 TO 5 INCH RANGE ARE EXPECTED THROUGH TONIGHT...SO HAVE OPTED TO DOWNGRADE THE WINTER STORM WARNING TO A WINTER WEATHER ADVISORY. OTHER CHANGES WERE TO TRIM HEADLINES OVER NW/W COUNTIES...AND EXPAND THE ADVISORY TO INCLUDE SOUTH CENTRAL AND SE COUNTIES. THE ADVISORY WILL ALSO EXPIRE AT MIDNIGHT...RATHER THAN CONTINUE THROUGH THE OVERNIGHT HOURS. WINDS WILL INCREASE THIS EVENING...WITH SUSTAINED SPEEDS IN THE 15 TO 25 MPH RANGE AND GUSTS AROUND 35 MPH OR SO. THE WINDS SHOULD LAG SLIGHTLY BEHIND THE HIGHER INTENSITY SNOW. ALSO...DUE TO THE HEAVY NATURE OF THE SNOW...AND VISIBILITY TRENDS THIS AFTERNOON...DON/T BELIEVE BLOWING SNOW WILL BE MUCH OF A PROBLEM IN TERMS OF VISIBILITY. WILL KEEP A MENTION OF PATCHY BLSN...BUT THE MAIN IMPACT SHOULD BE SHALLOW DRIFTING OVER ROADS. LIGHT SNOW OR FLURRIES WILL LINGER TUESDAY...OTHERWISE EXPECT ANOTHER SHOT OF COLDER AIR INTO WEDNESDAY. A CLIPPER SYSTEM WILL ARRIVE THURSDAY...AND WILL LIKELY HAVE THE HIGHEST IMPACT OVER THE NORTHEAST HALF OF IOWA WITH LIGHT TO POSSIBLY MODERATE ACCUMULATIONS. UPPER FLOW WILL THEN TRANSITION TO ZONAL FLOW WITH WARMING TEMPS THROUGH THE WEEKEND. THE NEXT CHANCE OF PRECIP WILL COME SUNDAY INTO MONDAY. .AVIATION...25/18Z LOW PRES TRACKING ESE FROM NE KS TO CENT MO THROUGH 00Z WITH DEFORMATION AXIS OF PRECIP TO ROTATE THROUGH CENTRAL IA. GENERALLY IFR CONDITIONS EXPECTED THROUGH 06Z...WITH LIFR AT TIMES DUE TO LOW CEILINGS AND OR MODERATE TO HEAVY SNOW. PRECIP CURRENTLY OVER TO SNOW IN NW IA...WITH A MIX OF SNOW AND FREEZING RAIN AT MCW AND ALO CONTINUING FOR A COUPLE OF MORE HOURS. TRANSITION TO SNOW GOES FROM NW TO SE THROUGH 00Z...WITH A 3 TO 4 HOUR PERIOD OF MODERATE TO HEAVY SNOW TO FOLLOW THE TRANSITION. SNOW TAPERS OFF EARLY THIS EVENING. MEANWHILE...NW WINDS INCREASE WITH GUSTS 25 TO 30KT FOR THE BALANCE OF THE TAF PERIOD. LOW CONFIDENCE IN ACTUAL VSBY REDUCING BLOWING SNOW DUE TO THE WETNESS OF THE SNOWFALL...BUT WILL MONITOR. CEILINGS GRADUALLY RISE AFT 06Z...WITH VFR CONDITIONS EXPECTED MOST PLACES AFT 12Z. && .DMX WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR ADAIR- APPANOOSE-BLACK HAWK-BOONE-BREMER-BUTLER-CLARKE-DALLAS-DAVIS- DECATUR-FRANKLIN-GREENE-GRUNDY-GUTHRIE-HAMILTON-HARDIN-JASPER- LUCAS-MADISON-MAHASKA-MARION-MARSHALL-MONROE-POLK-POWESHIEK- STORY-TAMA-UNION-WAPELLO-WARREN-WAYNE. && $$ PUBLIC...KINNEY AVIATION...MOYER ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1039 PM MST SUN FEB 24 2008 .AVIATION...FOR THE 06Z TAF...MAIN CONCERNS FOR THIS TAF PERIOD WILL BE COLD FRONTAL PASSAGE EARLY IN THE NEXT FEW HOURS FOLLOWED BY STRONG NORTHERLY WINDS BEHIND THE FRONT. 00Z MODEL GUIDANCE HAS INCREASED CONFIDENCE THAT WINDS WILL EXCEED ADVISORY CRITERIA AFTER ABOUT 15Z MONDAY FOR BOTH KGLD AND KMCK. COULD EASILY SEE GUSTS OF 35 TO 40KTS...POSSIBLY APPROACHING 50KTS...AFTER 15Z. STONG WINDS SHOULD CONTINUE THROUGH AROUND 00Z TUESDAY BEFORE SUBSIDING QUICKLY. OPTED TO LEAVE PRECIP OUT OF THE KMCK TAF AS CONFIDENCE IN CARRYING A PREVAILING PRECIP GROUP IS LOW AT THIS TIME BUT FUTURE SHIFTS SHOULD MONITOR TRENDS AND ADJUST ACCORDINGLY. && .PREV DISCUSSION... /ISSUED 945 PM MST SUN FEB 24 2008/ .UPDATE...HAVE UPDATED FIRST AND SECOND PERIODS (TONIGHT AND MONDAY) FOR ALL PARAMETERS INCLUDING THE ISSUANCE OF A WIND ADVISORY. LATEST 00Z GUIDANCE AND LOCAL WIND GUST PROGRAM BASED OFF THE NAM STRONGLY FAVOR ADVISORY CRITERIA WINDS BOTH SUSTAINED AND IN GUSTS STARTING AROUND 15Z AND CONTINUING THROUGH 23Z MONDAY. PER COORDINATION WITH SURROUNDING OFFICES HAVE GONE AHEAD AND ISSUED THE WIND ADVISORY FOR THE ENTIRE FORECAST AREA. OTHER CONCERNS TONIGHT ARE FOR PRECIP...INCLUDING SOME ELEVATED THUNDER ACROSS THE SOUTHEAST PORTION OF THE AREA. 18Z NAM AND 00Z SWODY1 WERE INDICATING AN AREA OF INCREASING MID LEVEL MOISTURE ALONG WITH MID LEVEL THETA-E CONVERGENCE AND INCREASING JET DIVERGENCE ACROSS THIS AREA WHILE THE 00Z NAM/GFS AND RUC SHOW IT ACROSS THE NORTH AND BASED ON LATEST RADAR IMAGERY FURTHER NORTH YET. THROUGH 06Z NOTHING EXPECTED BUT THROUGH 12Z MOISTURE WILL INCREASE IN THE LOWER LEVELS AS THE FRONT MOVES THROUGH. MID LEVEL LAPSE RATES ARENT ALL THAT BAD AND MODELS ARE PAINTING SOME VERY LIGHT QPF ACROSS THE AREA. PROBABLY SHOULD HAVE LEFT IT IN BUT CONFIDENCE JUST NOT HIGH ENOUGH TO DO IT SO HAVE PULLED IT. BASED ON THE 00Z DATA THE THUNDER THREAT APPEARS TO BE OUT OF OUR AREA. HAVE TWEAKED THE 3 HOURLY TEMP/DP GRIDS AS WELL AS ITS QUITE WARM FOR THIS TIME OF NIGHT IN LATE FEBRUARY. OVERNIGHT LOWS COULD BE WITHIN 10 DEGREES OF OUR NORMAL HIGHS FOR THIS TIME OF YEAR. THAT SHOULD ABOUT DO IT FOR NOW. THANKS LBF/GID/DDC FOR COORDINATION ON THE ADVISORY. && && .GLD WATCHES/WARNINGS/ADVISORIES... KS...WIND ADVISORY FROM 8 AM MST /9 AM CST/ TO 5 PM MST /6 PM CST/ MONDAY FOR KSZ001>004-013>016-027>029-041-042. NE...WIND ADVISORY FROM 8 AM MST /9 AM CST/ TO 5 PM MST /6 PM CST/ MONDAY FOR NEZ079>081. CO...WIND ADVISORY FROM 8 AM TO 5 PM MST MONDAY FOR COZ090>092. && $$ FOLTZ/DDT ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 945 PM MST SUN FEB 24 2008 .UPDATE...HAVE UPDATED FIRST AND SECOND PERIODS (TONIGHT AND MONDAY) FOR ALL PARAMETERS INCLUDING THE ISSUANCE OF A WIND ADVISORY. LATEST 00Z GUIDANCE AND LOCAL WIND GUST PROGRAM BASED OFF THE NAM STRONGLY FAVOR ADVISORY CRITERIA WINDS BOTH SUSTAINED AND IN GUSTS STARTING AROUND 15Z AND CONTINUING THROUGH 23Z MONDAY. PER COORDINATION WITH SURROUNDING OFFICES HAVE GONE AHEAD AND ISSUED THE WIND ADVISORY FOR THE ENTIRE FORECAST AREA. OTHER CONCERNS TONIGHT ARE FOR PRECIP...INCLUDING SOME ELEVATED THUNDER ACROSS THE SOUTHEAST PORTION OF THE AREA. 18Z NAM AND 00Z SWODY1 WERE INDICATING AN AREA OF INCREASING MID LEVEL MOISTURE ALONG WITH MID LEVEL THETA-E CONVERGENCE AND INCREASING JET DIVERGENCE ACROSS THIS AREA WHILE THE 00Z NAM/GFS AND RUC SHOW IT ACROSS THE NORTH AND BASED ON LATEST RADAR IMAGERY FURTHER NORTH YET. THROUGH 06Z NOTHING EXPECTED BUT THROUGH 12Z MOISTURE WILL INCREASE IN THE LOWER LEVELS AS THE FRONT MOVES THROUGH. MID LEVEL LAPSE RATES ARENT ALL THAT BAD AND MODELS ARE PAINTING SOME VERY LIGHT QPF ACROSS THE AREA. PROBABLY SHOULD HAVE LEFT IT IN BUT CONFIDENCE JUST NOT HIGH ENOUGH TO DO IT SO HAVE PULLED IT. BASED ON THE 00Z DATA THE THUNDER THREAT APPEARS TO BE OUT OF OUR AREA. HAVE TWEAKED THE 3 HOURLY TEMP/DP GRIDS AS WELL AS ITS QUITE WARM FOR THIS TIME OF NIGHT IN LATE FEBRUARY. OVERNIGHT LOWS COULD BE WITHIN 10 DEGREES OF OUR NORMAL HIGHS FOR THIS TIME OF YEAR. THAT SHOULD ABOUT DO IT FOR NOW. THANKS LBF/GID/DDC FOR COORDINATION ON THE ADVISORY. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...WIND ADVISORY FROM 8 AM MST /9 AM CST/ TO 5 PM MST /6 PM CST/ MONDAY FOR KSZ001>004-013>016-027>029-041-042. NE...WIND ADVISORY FROM 8 AM MST /9 AM CST/ TO 5 PM MST /6 PM CST/ MONDAY FOR NEZ079>081. CO...WIND ADVISORY FROM 8 AM TO 5 PM MST MONDAY FOR COZ090>092. && $$ DDT ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 447 PM MST SUN FEB 24 2008 .AVIATION...UPDATE FOR THE 00Z TAFS. AVAIATION FORECAST CONCERNS FOCUS ON THE TIMING OF THE INCREASED NORTHERLY WINDS AFTER THE COLD FRONT PUSHES THROUGH THE AREA MONDAY MORNING. FAIRLY GOOD CONCENSUS THAT WIND GUSTS UP TO 45 MPH ARE POSSIBLE FOR KGLD FROM 15Z UNTIL 23Z AND FOR KMCK FROM 18Z UNTIL 23Z. ALSO DURING THIS SAME TIME...MVFR CONDITIONS ARE POSSIBLE WITH A LOW LEVEL CLOUD DECK THROUGH THE END OF THE TAF PERIOD. PREVIOUS TO THIS...VFR CONDITIONS SHOULD PREVAIL. THERE IS A SLIGHT CHANCE OF RAIN MIXED WITH SNOW FOR KGLD FROM 06Z UNTIL 12Z...AND FROM 06Z THROUGH 18Z FOR KMCK. I WILL LET NEXT SHIFT AND PRECIP DETAILS WHEN THAT TIME APPROACHES THE FIRST SIX HOURS OF THE TAF PERIOD. && .PREV DISCUSSION... /ISSUED 237 PM MST SUN FEB 24 2008/ .DISCUSSION...A TROUGH WILL MOVE EAST OF THE ROCKIES TONIGHT. THIS TROUGH WILL MOVE QUICKLY EAST OF THE ROCKIES ON MONDAY. NORTHWEST FLOW WILL FOLLOW THROUGH THE REMAINDER OF THIS PART OF THE FORECAST THROUGH WEDNESDAY NIGHT. A SURFACE LOW WILL SET UP OVER NORTHWEST KANSAS TONIGHT AND WILL MOVE INTO EASTERN KANSAS BY MONDAY MORNING. HIGH PRESSURE WILL FOLLOW AND LAST THROUGH WEDNESDAY NIGHT. THE MAIN FORECAST ISSUES ARE POPS/WX FOR TONIGHT/EARLY MONDAY AND WIND ON MONDAY. A TROUGH COMES THROUGH LATE TONIGHT BUT MOISTURE IS LACKING. THE BEST MOISTURE IS IN THE NORTHEAST FORECAST AREA ACCORDING TO THE NAM. ANY PRECIPITATION SHOULD OCCUR AFTER 06Z SO PLAN TO MAKE POPS SILENT FOR THIS EVENING EXCEPT IN EASTERN COLORADO. OTHERWISE PLAN ON KEEP CURRENT SLIGHT CHANCE POPS IN PLACE FOR LATE TONIGHT WITH PRECIPITATION ENDING IN THE EASTERN ZONES MONDAY MORNING. FORECAST SOUNDINGS INDICATE THAT PRECIPITATION COULD BE MIXED WITH RA/SN. THE REMAINDER OF THE FORECAST FROM MONDAY AFTERNOON THROUGH WEDNESDAY NIGHT SHOULD BE DRY WITH HIGH PRESSURE/SUBSIDENCE. THE CURRENT FORECAST HAS SOME SLIGHT CHANCE POPS FOR MONDAY NIGHT IN EASTERN COLORADO. AT THIS TIME THERE APPEARS TO BE NO FORCING ASSOCIATED WITH SOME MOISTURE MOVING SOUTH OUT OF WYOMING BUT IN NORTHWEST FLOW TIMING SHORTWAVES CAN BE TOUGH. THE BEST MOISTURE IS WEST OF THE FORECAST AREA SO IF ANY PRECIPITATION OCCURS IT IS LIKELY TO BE OUTSIDE OF THE FORECAST AREA. DUE TO UNCERTAINTY WILL KEEP HIGH SILENT POPS IN THE EASTERN COLORADO ZONES. WIND IS THE NEXT ISSUE FOR MONDAY BEHIND THE EXITING TROUGH. THE SURFACE PRESSURE GRADIENT TIGHTENS UP GOOD MONDAY MORNING. THE RUC IS SHOWING SUSTAINED WIND AROUND 30KTS WITH GUSTS TO 40KTS. THE NAM ALSO SUPPORTS THIS WITH BUFKIT SHOWING 40KTS ABLE TO BE MIXED DOWN. THE RUC ALSO INDICATES STRONG PRESSURE RISES BEHIND THE EXITING LOW. ALTHOUGH CONFIDENCE IS GOOD FOR A WIND ADVISORY EVENT ON MONDAY AM HESITANT TO ISSUE FOR A 2ND PERIOD WHICH AGREES WITH COORDINATION FROM SURROUNDING OFFICES. 850 TEMPERATURES FALL SEVERAL DEGREES ON MONDAY AND A FEW DEGREES MORE ON TUESDAY BEFORE REBOUNDING ON WEDNESDAY. HIGHS WILL BE MUCH COOLER ON MONDAY/TUESDAY WITH READINGS IN THE LOWER 40S. WEDNESDAYS TEMPERATURES SHOULD RISE BACK INTO THE UPPER 40S/LOWER 50S. MIN TEMPERATURES SHOULD BE RELATIVELY MILD TONIGHT WITH READINGS IN THE MID/UPPER 30S FALLING TO NEAR NORMAL READINGS FOR THE REMAINING NIGHTS. IN THE EXTENDED...(DAYS 4 AND 5)...THURSDAY-FRIDAY...UPPER FLOW IS NORTHWEST DURING THIS TIME. A SURFACE TROUGH WILL BE ACROSS EASTERN COLORADO ON THURSDAY WITH A FRONT MOVING INTO NORTHWEST KANSAS THURSDAY EVENING. HIGH PRESSURE BUILD INTO THE AREA ON FRIDAY. SOME DYNAMICS/MOISTURE ARE AVAILABLE WITH THE FRONT FOR SOME R-/S-. BUFKIT POINT SOUNDINGS INDICATE THE MOISTURE PROFILE SATURATES BRIEFLY BETWEEN 06-12Z FRIDAY. CONSEQUENTLY HAVE ADDED SLIGHT CHANCE POPS FOR THIS EVENT. SUBSIDENCE BUILDS IN BEHIND THE WAVE ON FRIDAY WITH DRY CONDITIONS. 850MB TEMPERATURES ARE WARM AHEAD OF THE FRONT AND THEN COOL 6-8 DEGREES BEHIND THE FRONT. TEMPERATURES SHOULD BE IN THE LOWER/MID 50S ON THURSDAY COOLING TO THE UPPER 40S ON FRIDAY. MIN TEMPERATURES WILL BE A FEW DEGREES ABOVE NORMAL WITH READINGS IN THE UPPER 20S. (DAYS 6 AND 7)...FRI NIGHT-SUNDAY...MEDIUM RANGE MODELS AND BEGIN TO DIVERGE THIS PERIOD ON TIMING OF STRONG SHORT WAVE TROUGH THAT WILL IMPACT THE AREA SUNDAY. GFS ABOUT 12 HOURS FASTER THAN ECMWF...AND AS A RESULT MODELS MUCH DIFFERENT WITH TEMPS DUE TO LARGE DIFFERENCES IN TIMING OF SFC FEATURES. GFS ENSEMBLE DATA WOULD TEND TO SUPPORT SLOWER SOLUTION...ESPECIALLY 00Z CYCLE AND AT THIS POINT WILL GENERALLY TRY TO KEEP FORECAST IN MIDDLE OF ECMWF AND GFS SOLUTIONS. AS A RESULT WARMED TEMPS A FEW DEGREES ON SATURDAY AS ENS MEAN DATA HAS H85 TEMPS WARMING INTO THE 10-15C RANGE. ECMWF IS NOTABLY COOLER...BUT THIS APPEARS DUE TO IT BEING SLOWER MOVING OUT SFC RIDGE FROM THE AREA AND AT THIS TIME RANGE THINK STAYING CLOSER TO MEAN DATA WILL BE THE WAY TO GO. ALSO WILL ADD POPS FOR SHORT WAVE TROUGH SWEEPING OVER THE AREA IN THE LATE SAT NIGHT-SUNDAY TIME FRAME. STILL TO MUCH DIFFERENCES IN THE MODELS WITH TIMING AND TEMPS TO GO TO HIGH ON POPS OR BE VERY CONFIDENT PRECIP TYPE. && && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ BLM/FS/JRM ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 237 PM MST SUN FEB 24 2008 .DISCUSSION...A TROUGH WILL MOVE EAST OF THE ROCKIES TONIGHT. THIS TROUGH WILL MOVE QUICKLY EAST OF THE ROCKIES ON MONDAY. NORTHWEST FLOW WILL FOLLOW THROUGH THE REMAINDER OF THIS PART OF THE FORECAST THROUGH WEDNESDAY NIGHT. A SURFACE LOW WILL SET UP OVER NORTHWEST KANSAS TONIGHT AND WILL MOVE INTO EASTERN KANSAS BY MONDAY MORNING. HIGH PRESSURE WILL FOLLOW AND LAST THROUGH WEDNESDAY NIGHT. THE MAIN FORECAST ISSUES ARE POPS/WX FOR TONIGHT/EARLY MONDAY AND WIND ON MONDAY. A TROUGH COMES THROUGH LATE TONIGHT BUT MOISTURE IS LACKING. THE BEST MOISTURE IS IN THE NORTHEAST FORECAST AREA ACCORDING TO THE NAM. ANY PRECIPITATION SHOULD OCCUR AFTER 06Z SO PLAN TO MAKE POPS SILENT FOR THIS EVENING EXCEPT IN EASTERN COLORADO. OTHERWISE PLAN ON KEEP CURRENT SLIGHT CHANCE POPS IN PLACE FOR LATE TONIGHT WITH PRECIPITATION ENDING IN THE EASTERN ZONES MONDAY MORNING. FORECAST SOUNDINGS INDICATE THAT PRECIPITATION COULD BE MIXED WITH RA/SN. THE REMAINDER OF THE FORECAST FROM MONDAY AFTERNOON THROUGH WEDNESDAY NIGHT SHOULD BE DRY WITH HIGH PRESSURE/SUBSIDENCE. THE CURRENT FORECAST HAS SOME SLIGHT CHANCE POPS FOR MONDAY NIGHT IN EASTERN COLORADO. AT THIS TIME THERE APPEARS TO BE NO FORCING ASSOCIATED WITH SOME MOISTURE MOVING SOUTH OUT OF WYOMING BUT IN NORTHWEST FLOW TIMING SHORTWAVES CAN BE TOUGH. THE BEST MOISTURE IS WEST OF THE FORECAST AREA SO IF ANY PRECIPITATION OCCURS IT IS LIKELY TO BE OUTSIDE OF THE FORECAST AREA. DUE TO UNCERTAINTY WILL KEEP HIGH SILENT POPS IN THE EASTERN COLORADO ZONES. WIND IS THE NEXT ISSUE FOR MONDAY BEHIND THE EXITING TROUGH. THE SURFACE PRESSURE GRADIENT TIGHTENS UP GOOD MONDAY MORNING. THE RUC IS SHOWING SUSTAINED WIND AROUND 30KTS WITH GUSTS TO 40KTS. THE NAM ALSO SUPPORTS THIS WITH BUFKIT SHOWING 40KTS ABLE TO BE MIXED DOWN. THE RUC ALSO INDICATES STRONG PRESSURE RISES BEHIND THE EXITING LOW. ALTHOUGH CONFIDENCE IS GOOD FOR A WIND ADVISORY EVENT ON MONDAY AM HESITANT TO ISSUE FOR A 2ND PERIOD WHICH AGREES WITH COORDINATION FROM SURROUNDING OFFICES. 850 TEMPERATURES FALL SEVERAL DEGREES ON MONDAY AND A FEW DEGREES MORE ON TUESDAY BEFORE REBOUNDING ON WEDNESDAY. HIGHS WILL BE MUCH COOLER ON MONDAY/TUESDAY WITH READINGS IN THE LOWER 40S. WEDNESDAYS TEMPERATURES SHOULD RISE BACK INTO THE UPPER 40S/LOWER 50S. MIN TEMPERATURES SHOULD BE RELATIVELY MILD TONIGHT WITH READINGS IN THE MID/UPPER 30S FALLING TO NEAR NORMAL READINGS FOR THE REMAINING NIGHTS. IN THE EXTENDED...(DAYS 4 AND 5)...THURSDAY-FRIDAY...UPPER FLOW IS NORTHWEST DURING THIS TIME. A SURFACE TROUGH WILL BE ACROSS EASTERN COLORADO ON THURSDAY WITH A FRONT MOVING INTO NORTHWEST KANSAS THURSDAY EVENING. HIGH PRESSURE BUILD INTO THE AREA ON FRIDAY. SOME DYNAMICS/MOISTURE ARE AVAILABLE WITH THE FRONT FOR SOME R-/S-. BUFKIT POINT SOUNDINGS INDICATE THE MOISTURE PROFILE SATURATES BRIEFLY BETWEEN 06-12Z FRIDAY. CONSEQUENTLY HAVE ADDED SLIGHT CHANCE POPS FOR THIS EVENT. SUBSIDENCE BUILDS IN BEHIND THE WAVE ON FRIDAY WITH DRY CONDITIONS. 850MB TEMPERATURES ARE WARM AHEAD OF THE FRONT AND THEN COOL 6-8 DEGREES BEHIND THE FRONT. TEMPERATURES SHOULD BE IN THE LOWER/MID 50S ON THURSDAY COOLING TO THE UPPER 40S ON FRIDAY. MIN TEMPERATURES WILL BE A FEW DEGREES ABOVE NORMAL WITH READINGS IN THE UPPER 20S. (DAYS 6 AND 7)...FRI NIGHT-SUNDAY...MEDIUM RANGE MODELS AND BEGIN TO DIVERGE THIS PERIOD ON TIMING OF STRONG SHORT WAVE TROUGH THAT WILL IMPACT THE AREA SUNDAY. GFS ABOUT 12 HOURS FASTER THAN ECMWF...AND AS A RESULT MODELS MUCH DIFFERENT WITH TEMPS DUE TO LARGE DIFFERENCES IN TIMING OF SFC FEATURES. GFS ENSEMBLE DATA WOULD TEND TO SUPPORT SLOWER SOLUTION...ESPECIALLY 00Z CYCLE AND AT THIS POINT WILL GENERALLY TRY TO KEEP FORECAST IN MIDDLE OF ECMWF AND GFS SOLUTIONS. AS A RESULT WARMED TEMPS A FEW DEGREES ON SATURDAY AS ENS MEAN DATA HAS H85 TEMPS WARMING INTO THE 10-15C RANGE. ECMWF IS NOTABLY COOLER...BUT THIS APPEARS DUE TO IT BEING SLOWER MOVING OUT SFC RIDGE FROM THE AREA AND AT THIS TIME RANGE THINK STAYING CLOSER TO MEAN DATA WILL BE THE WAY TO GO. ALSO WILL ADD POPS FOR SHORT WAVE TROUGH SWEEPING OVER THE AREA IN THE LATE SAT NIGHT-SUNDAY TIME FRAME. STILL TO MUCH DIFFERENCES IN THE MODELS WITH TIMING AND TEMPS TO GO TO HIGH ON POPS OR BE VERY CONFIDENT PRECIP TYPE. && .AVIATION...VFR CONDITIONS WILL DOMINATE MOST IF NOT ALL OF THE 18Z TAF PERIOD. ALTHOUGH...AFTER 15Z...MVFR CONDITIONS MAY AFFECT KMCK A LITTLE MORE THAN KGLD WITH A LOWER LOW LEVEL CLOUD DECK MOVING OVER THE AREA BEHIND THE COLD FRONT. THERE IS A SLIGHT CHANCE FOR SOME LIGHT RAIN MIXED WITH LIGHT SNOW THIS EVENING BUT CHOSE TO LEAVE MENTION OF THAT OUT OF THE TAFS. NEXT SHIFT MAY WANT TO INCLUDE MENTION OF PRECIP AS THAT TIME FRAME APPROACHES THE FIRST SIX HOURS OF THE TAF. WITH THE PASSAGE OF THE COLD FRONT EARLY MONDAY...LOW LEVEL WIND SHEAR MAY BE A BRIEF CONCERN FOR BOTH KGLD AND KMCK. BEHIND THE FRONT...WINDS WILL INCREASE FROM THE NORTH AND NORTHWEST TO 20 TO 30 MPH WITH SOME GUSTS REACHING UP TO 40 MPH. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ FS/JRM/BLM ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 242 PM CST SUN FEB 24 2008 .DISCUSSION... DAYS 1-2... WINDS TOMORROW AND CHANCES FOR ANY PRECIP IN THE NORTH WILL BE THE MAIN FORECAST CONCERN. 500MB HEIGHT RISES OF 120 TO 160 METERS WERE FOUND ACROSS ACROSS WESTERN PORTIONS OF KS AND TX AT 12Z THIS MORNING. THE SHORTWAVE TROUGH THAT BROUGHT OUR SNOW YESTERDAY WAS QUICKLY MOVING EAST, AND THE NEXT SHORTWAVE COMING ONTO THE COAST. WV LOOP HAS THE SYSTEM HEADING INTO NV, WITH A 110 KT JET ALONG THE FRONT SIDE OF IT. WARM 850MB TEMPS WERE ACROSS THE SOUTHERN ROCKIES AND WESTERN PLAINS AHEAD OF THE SYSTEM. TEMPS ACROSS THE CWA HAVE WARMED NICELY INTO 50S AND 60S EXCEPT FOR THE SNOW COVERED AREAS IN THE NORTHEAST. THE SHORTWAVE OVER NV WILL CONTINUE TO APPROACH THE PLAINS TONIGHT, WITH THE SFC TROUGH DEEPENING IN RESPONSE. SAT LOOP SHOWS CIRRUS BEGINNING TO STREAM INTO OUR WESTERN COUNTIES, WHICH MATCHES WELL WITH MODEL RH AT HIGH LEVELS. THINK THAT INCREASING SOUTHWESTERLY WINDS AND HIGH CLOUDS TONIGHT WILL KEEP US FROM GETTING A REPEAT OF LAST NIGHT`S FOG. THE WINDS AND CIRRUS SHOULD ALSO KEEP READINGS FROM RADIATING OUT TOO MUCH, SO CONTINUED WITH LOWS IN THE MID 30S TO NEAR 40. THE TROUGH WILL CONTINUE TO MOVE EASTWARD INTO THE PLAINS ON MONDAY. THE MODELS HAVE BEEN TRENDING SLIGHTLY SLOWER AND A HAIR DEEPER WITH THE SYSTEM. LOW LEVEL MOISTURE WILL NOT BE ALL THAT GREAT, BUT SOME GOOD MID LEVEL RH IS ASSOCIATED WITH THE SYSTEM. THINK THAT THE MAJORITY OF THE PRECIP WILL REMAIN TO OUR NORTHEAST, BUT NAM MODEL SOUNDINGS FOR THE HYS AREA HAVE MID LEVEL MOISTURE SATURATING DOWN. GFS AND UKMET ALSO SQUEEZE OUT SOME PRECIP IN OUR NORTH, AND THE 15Z SREF HAS SOME LOW PROBABILITIES FOR RAIN. AM NOT TERRIBLY IMPRESSED, BUT CAN`T COMPLETELY RULE OUT A FEW SHOWERS REACHING THE GROUND, SO PUT IN SOME VERY LOW POPS MONDAY AFTERNOON. THE SFC LOW WILL BE EAST OF US BY AFTERNOON, WITH GOOD COLD AIR ADVECTION AND A STRONG GRADIENT ON THE BACKSIDE OF THE SYSTEM. RUC AND NAM HAVE SPEEDS GETTING ABOVE 25 KTS, AND SREF HAS SOME LOW PROBABILITIES OF THE SAME. ON THE OTHER HAND, 850MB WINDS ARE NOT AS HIGH AS THEY COULD BE, AND THE UKMET IS NOT AS STRONG WITH THE SFC WINDS. AFTER CONSULTING WITH SURROUNDING OFFICES, WILL HOLD OFF ON AN ADVISORY FOR NOW AND JUST INCLUDE THE WINDY WORDING. HIGHS WILL DEPEND ON EXACTLY WHEN THE FRONT COMES THROUGH. SOUTHERN COUNTIES COULD GET FAIRLY WARM IN THE MID 50S AS THE FRONT WILL NOT MOVE THROUGH THERE UNTIL THE AFTERNOON. THE NORTHEAST, PARTICULARLY WHERE THERE IS CLOUD COVER, WILL NOT GET OUT OF THE 40S WITH COLD AIR ADVECTION FOR MOST OF THE DAY. NORTH TO NORTHWEST FLOW SETS UP MONDAY NIGHT AS THE UPPER TROUGH DIGS INTO THE MS VALLEY. HIGH PRESSURE SETS IN BEHIND THE FRONT ACROSS THE ROCKIES AND WESTERN PLAINS, ALTHOUGH THE GRADIENT STAYS FAIRLY TIGHT FOR MUCH OF THE NIGHT. A WEAK SHORTWAVE WILL MOVE THROUGH CO ON THE BACKSIDE OF THE MAIN TROUGH, BUT THINK THAT ANY SNOW PRODUCTION WILL STAY TO OUR WEST. NORTHERLY WINDS SHOULD CONTINUE, AND LOWS WILL BE MAINLY IN THE 20S. NORTH TO NORTHWEST FLOW AND HIGH PRESSURE WILL CONTINUE TUESDAY. 850MB TEMPS WILL BE SLIGHTLY COOLER AS COLD AIR GETS REINFORCED. EVEN WITH SUNSHINE, THINK THAT OUR NORTHEAST WILL HAVE TROUBLE GETTING OUT OF THE 30S, WITH WARMER TEMPS IN OUR SOUTHWEST. DAYS 3-7... A COOL DOME OF HIGH PRESSURE WILL CROSS THE CNTL PLAINS TUESDAY WITH NW DOWNSLOPE FLOW RETURNING TO WRN KS BY MID WEEK. BASED ON RUN TO RUN CONSISTENCY AND 85H TEMP PROGS SEE LITTLE REASON TO DISAGREE WITH THE WARMING TREND CURRENTLY ADVERTISED IN THE GRIDS WHICH INCLUDES HIGHS IN THE 60S ON THURSDAY. THE FIRST OF TWO UPPER LEVEL DISTURBANCES REMAIN ARE PROGGED TO CROSS THE CWA LATE WEEK WHICH WILL BRING A COLD FRONT THROUGH THE AREA BY FRIDAY. ANY COOL DOWN BEHIND THIS FRONT HOWEVER WILL BE BRIEF AS A S/W RIDGE ALOFT IS EXPECTED QUICKLY CROSSES THE ROCKIES INTO THE PLAINS BY SATURDAY. OUR NEXT MORE SIG UPPER LVL TROF IS THEN PROGGED TO MOVE ONTO THE WEST COAST LATE FRIDAY AND THEN DIG SOUTHEAST TOWARDS NEW MEXICO BY SUNDAY. EVEN THOUGH THE ENSEMBLES AND MODELS DIFFER SOME ON TIMING AND TRACK THEY ALL ARE STILL IN GENERALLY GOOD AGREEMENT THAT THERE SHOULD BE SOME DECENT MOISTURE RETURN AHEAD OF THIS WEEKEND SYSTEM. AS A RESULT WILL BE FOLLOWING HPC GUIDANCE AND INTRODUCING SLT CHC POPS INTO DAY 7. CONFIDENCE HOWEVER REMAINS LOW ON WHERE OUT COLD FRONT WILL BE AND TIMING/TRACK OF THIS NEXT PACIFIC SYSTEM SO WILL BE VERY GENERAL IN BOTH POPS AND TEMPS. .AVIATION... WINDS EXPECTED TO BE A LITTLE STRONGER TONIGHT THAN LAST NIGHT AS SFC PRESSURES FALL ALONG THE WESTERN HIGH PLAINS IN RESPONSE TO OUR NEXT UPPER S/W TROF. WITH BETTER MIXING THINK FOG/ST POTENTIAL WILL BE LESS LIKELY TOMORROW THAN EARLIER TODAY. TIGHT PRESSURE GRADIENT AND GOOD MIXING POTENTIAL EXPECTED BEHIND THIS FRONT SO WILL KEEP WINDS AT LEAST IN THE WINDY CAT DURING THE DAY ON MONDAY. && .PRELIMINARY POINT TEMPS/POPS... DDC 37 53 25 43 / 0 0 0 0 GCK 36 54 24 43 / 0 0 0 0 EHA 37 55 25 46 / 0 0 0 0 LBL 38 55 25 45 / 0 0 0 0 HYS 34 45 22 38 / 0 20 10 0 P28 40 53 28 42 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN26/18/18 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 310 PM EST SUN FEB 24 2008 .SYNOPSIS... HIGH PRESSURE SOUTH OF NEW ENGLAND WILL WEAKEN AND MOVE TO THE EAST TONIGHT. A COLD FROM WILL APPROACH THE STATE FROM THE NORTHWEST TONIGHT AND BECOME STATIONARY OVER NORTHERN MAINE MONDAY. LOW PRESSURE OVER THE CENTRAL PLAINS MONDAY WILL TRACK EASTWARD INTO WESTERN PENNSYLVANIA BY LATE TUESDAY THEN NORTHEAST ALONG THE DOWNEAST COAST ON WEDNESDAY. THIS SYSTEM MAY BRING ANOTHER SIGNIFICANT ROUND OF SNOW AND MIXED PRECIPITATION TO THE AREA TUESDAY NIGHT AND WEDNESDAY. BRISK NORTHWEST WINDS AND ANOTHER BLAST OF ARCTIC AIR CAN BE EXPECTED LATE WEDNESDAY NIGHT THROUGH THURSDAY NIGHT WITH COLD HIGH PRESSURE TO SETTLE OVER THE REGION ON FRIDAY. && .NEAR TERM /THROUGH MONDAY/... HIGH PRESSURE WILL WEAKEN TO THE SOUTH OF THE AREA TONIGHT. A COLD FRONT WILL APPROACH FROM THE NORTHWEST THIS EVENING. EXPECT THIS SYSTEM TO WEAKEN AS IT APPROACHES AND BECOMES STATIONARY OVER THE NORTHERN PORTION OF THE FORECAST AREA MONDAY. ALL GUIDANCE FOR SKY AND POPS NEXT 24 HOURS LOOKS OVER DONE. LOOKS LIKE MIDDLE AND LOWER CLOUDS ASSOCIATED WITH APPROACHING FROM NEAR JAMES BAY ARRIVING IN NORTH THIS EVENING. WILL PLAY DOWN LOW MODEL POPS ASSOCIATED WITH THIS SYSTEM UNTIL LATER MONDAY THEN INTRODUCE LOW NUMBERS IN NORTHWEST. WILL USE GMOS FOR WINDS...TEMPERATURE AND DEW POINT. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... MAIN FOCUS THIS TIME FRAME WILL BE ON THE STORM SYSTEM WHICH IS XPCTD TO AFFECT OUR FA TUESDAY NIGHT THROUGH WED... LOOKING MORE AND MORE LIKE THIS SYSTEM WILL BE THE NXT MAJOR WNTR STORM TO AFFECT OUR REGION AFTER A SHORT BREAK... IN THE MEANTIME...XPCT A COLD FRONT TO SAG SEWRD INTO NRN AREAS MON NGT THEN SAG SLOWLY SWRD INTO CENTRAL AREAS BY ERLY TUE. THIS FRONT LIKELY TO SPARK AND INCRS IN SW- ACTIVITY N AND W MON NGT REACHING CENTRAL AREAS ON TUE. STEADIER PRECIP ASSOCIATED W/ THE AFOREMENTIONED STORM SYSTEM THEN XPCTD TO SPREAD NEWRD ALONG THIS FRONT AND INTO THE FA FROM SW TO NE LATER TUE. THEREAFTER...CONCERNING THE UPCOMING STORM SYSTEM...12Z MODEL SUITE INCLUDING THE CANADIAN/ECMWF/SREF/NAM AND GFS ALL TAKE THE DEVELOPING LOW PRES SYSTEM OVER THE CENTRAL PLAINS ON MON AND TRACK IT ENE TO A POSN ALONG THE DOWNEAST COAST BY WED AM. UKMET IS THE OUTLIER TAKING THIS SYSTEM MUCH FARTHER S AND HAS BEEN THROWN OUT... NAM IS CHARACTERISTICALLY A LITTLE SLOWER BUT FOLLOWS A SIMILAR TRACK AND SCENARIO AS THE REST OF THE MODELS... MODEL CONSENSUS BRINGS .75 TO 1.25 INCHES OF LIQUID TO THE FA FROM LATE TUESDAY THRU WED W/ CRITICAL THCKNS VALS SUPPORTING ALL SNOW FOR CENTRAL AND NRN AREAS W/ A MIX DOWNEAST. UPSTREAM OFFICES ARE HOLDING OFF ON WATCHES ATTM AND WILL DO THE SAME HERE AS IT WOULD BE A 5TH PERIOD WATCH FOR US BUT IF CURRENT TRENDS CONTINUE WOULD RECOMMEND OUR OFFICE GO W/ WATCHES FOR CENTRAL AND NRN AREAS ON THE MDNGT SHIFT. && .LONG TERM /THURSDAY THROUGH SUNDAY/... THE START OF THE LONG TERM FIND THE GFS AND ECMWF IN FAIRLY GOOD AGREEMENT ON CONDITIONS. A LOW PRESSURE WILL BE EXITING THE AREA OVER THE CANADIAN MARITIMES AND HIGHER PRESSURE WILL BE BUILDING IN BEHIND. BOTH MODELS INDICATE THAT THERE WILL BE SOME TROUGHING INTO THE GULF OF MAINE. BY THURSDAY NIGHT THE HIGH PRESSURE WILL RIDGE INTO THE AREA. FRIDAY EVENING THE MODELS DIVERGE A BIT. THE GFS INDICATES THAT THE HIGH WILL BE CRESTED OVER THE AREA...THE ECMWF HAS THE HIGH EAST OF THE AREA WITH A LOW PRESSURE SYSTEM OVER THE NORTHERN GREAT LAKES. SATURDAY MORNING THE MODELS ARE IN BETTER AGREEMENT...BUT STILL DIFFER ON POSITION AND TIMING OF THE LOW. THE ECMWF MOVES THE LOW EAST OF THE AREA INTO THE CANADIAN MARITIMES BY SATURDAY NIGHT...THE GFS SLOW THE SYSTEM...MOVES IT OFF THE DOWNEAST COAST BY SATURDAY NIGHT. THEN INTO EASTERN NEW BRUNSWICK BY SUNDAY MORNING. THE GMOS SUPPORTS A BLENDED APPROACH THROUGH THE PERIOD. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... EXPECT VFR CONDITIONS NEXT 24 HOURS. LOW CLOUDS EXPECTED TO MOVE INTO NORTHERN AREAS MONDAY AHEAD OF A COLD FRONT...HOWEVER CEILING EXPECTED TO REMAIN VFR. VFR XPCTD SRN SITES W/ VFR/MVFR IN SW- N MON NGT INTO TUE. XPCT DETERIORATING CONDS ALL TAF SITES BY LATE TUE W/ THE APPROACH OF THE NXT MAJOR STORM SYSTEM DISCUSSED IN THE SHORT TERM SECTION ABOVE... PREDOM IFR/LIFR CONDS XPCTD LATE TUE THRU WED W/ SLOW IMPROVEMENT WED NGT INTO THU. VFR CONDS AGAIN XPCTD BY FRI AT ALL TAF SITES AS COLD DRY HGH PRES SETTLES OVR THE AREA. && .MARINE... NEAR TERM: INITIALLY UPDATING USING COMPROMISE BETWEEN RUC13 AND CARWRF. DURING THE DAY TODAY THE LIGHTER RUC13 SPEEDS APPEAR MORE REASONABLE SO HAVE UPDATE REMAINDER OF THE AFTERNOON USING RUC13. BEYOND RUC13 RANGE HAVE USED A 50/50 BLEND OF THE NAM12 AND THE GFS40 OUT TO THE END OF THE PERIOD. FOR WAVES: NO OBSERVATIONS AVAILABLE FROM 44027 BUT BASED ON OBS FROM 44034 WAVE MODEL NUMBERS STILL RUNNING 1 FOOT TOO LOW. SPECTRAL DATA AT CAR01 SUGGESTS PRIMARY WAVE GROUPS ARE SOUTHERLY SWELL AND SOUTHWEST WIND WAVE. APPEARS SWELL FIELD FROM MODEL TOO LOW BUT OFFSET BY WIND WAVE GROUP THAT IS CURRENTLY TOO HIGH. CURRENT OBS 4 TO 5 FEET PRIMARILY FROM SWELL FIELD...HOWEVER EXPECT INCREASE BACK TO 5 TO 6 FEET LATER THIS EVENING AS WIND FIELD INCREASES. SO WILL KEEP SCA. SHORT TERM: WNDS/SEAS XPCT TO REMAIN BLO SCA UNTIL TUE NGT WHEN AT LEAST CONDS XPCTD TO DEVELOP W/ TH APPROACH OF THE STORM SYSTEM FROM THE SW... && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 7 AM EST MONDAY FOR ANZ050-051. && $$ NEAR TERM...MIGNONE SHORT TERM...KHW LONG TERM...NORTON AVIATION...MIGNONE MARINE...MIGNONE/KHW me AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 840 PM EST MON FEB 25 2008 .UPDATE... UPDATED TO GO WITH PCLDY SKIES IN THE EVNG ACRS THE KEWEENAW AS DRY AIR OVER MN/SRN ONTARIO AS SHOWN ON 00Z INL RAOB/RECENT TAMDAR SDNG FM YQT HAS INVADED NRN LK SUP AND CAUSED SC TO BREAK UP THERE WITH UNFVRBL NLY FLOW AND ACYC FLOW AT H85. OTRW...CONTINUED INFLUX OF COLDER AIR ACRS LK SUP (00Z H85 TEMP -4C AT GRB...-13C AT INL...THEN -19C AT YPL) WL CAUSE LES TO DVLP OVERNGT. BUT DRYNESS OF AIRMASS AS WELL AS ICE COVER OVER WRN LK SUP AND BTWN THE KEWEENAW AND MQT WL TEND TO LIMIT AMTS. MORE MSTR NOTED NW OF INL/YPL. ARRIVAL OF THIS MSTR ON TUE MRNG IN CONCERT WITH DPVA/HGT FALLS ACCOMPANYING DIGGING SHRTWV NR LK WINNIPEG MAY RESULT IN A BIT MORE LES TMRW. && .SYNOPSIS... SOMEWHAT AMPLIFIED PATTERN OVER NORTH AMERICA AS NOTED ON WATER VAPOR LOOP AND RUC ANALYSIS. MEAN RIDGE IS OVER THE WEST COAST WITH A BROAD TROF OVER THE ERN 2/3RD OF CANADA AND UPR GREAT LAKES AND NE U.S. SRN STREAM SYSTEM MOVING THROUGH THE CENTRAL PLAINS IS PROJECTED TO MOVE THROUGH THE OHIO VALLEY TONIGHT AND TUE AND WILL NOT A SYNOPTIC IMPACT OUR UPR MI WX EXCEPT TO TIGHTEN NRLY GRADIENT OVER THE REGION ON BACK SIDE OF LOW. COLDER AIR MOVING IN LATE TONIGHT AND TUESDAY WITH ADVANCE OF SHORTWAVE FROM SRN MANITOBA WILL HELP GENERATE LES FOR AREAS DOWNSTREAM OF LAKE SUPERIOR IN NRLY FLOW. .SHORT TERM (TONIGHT AND TUESDAY)... BIG QUESTION TONIGHT WILL BE HOW LONG WILL IT TAKE FOR LES BANDS TO DEVELOP AS COLDEST AIR DOESN`T MOVE ACROSS THE AREA UNTIL LATE TONIGHT WITH ARRIVAL OF CLIPPER SHORTWAVE OVER SRN MANITOBA. INITIALLY OVER LAKE SUPERIOR THIS EVENING 850 MB TEMPS ARE FCST TO BE -10C TO -11C WHICH MAY NOT BE COLD ENOUGH TO GENERATE LES. GIVEN MARGINALLY COLD TEMPS FOR EVEN ICE IN THE CLOUDS...HAVE DECIDED TO THROW IN SOME PATCHY FZDZ FOR WEST AND NCNTRL COUNTIES IN NRLY UPSLOPE FLOW. WITH APPROACH OF CLIPPER SHORTWAVE OVERNIGHT...MODELS THEN SHOW 850 MB TEMPS LOWERING TO -16 TO -18 LATE TONIGHT WHICH SHOULD HELP GENERATE SOME LES. SO GIVEN THE SLOWER ADVANCE OF COLD AIR UNTIL LATE TONIGHT GENERALLY TRIMMED BACK ACCUMS TONIGHT TO INCH OR LESS OVER THE FAVORED NRLY UPSLOPE AREAS IN WEST AND NCNTRL ZONES...BUT KEPT IN LIKELY POPS FOR THE OVERNIGHT IN THESE COUNTIES. BY TUE...THE COLDEST AIR IS OVER THE UPR GREAT LAKES WITH 850 MB TEMPS LOWERING TO AROUND -19C. HOWEVER...SFC-850 MB FLOW IS ALSO BECOMING SHARPLY ANTICYCLONIC BY THIS TIME WITH DRY AIR AT LOW-LEVELS ADVECTING IN FROM ONTARIO. THE DRY AIR COMBINED WITH INCREASED SUN ANGLE/DIURNAL HEATING THIS TIME OF YEAR...MAY DISRUPT LES BANDS A BIT DURING THE DAY. FOR THESE REASONS ALSO TRIMMED BACK ACCUMS TO AROUND AN INCH FOR WEST AND CENTRAL ZONES IN UPSLOPE NRLY FLOW. THERE COULD BE SOME LOCALLY HIGHER AMOUNTS (AROUND 2 INCHES) BETWEEN MARQUETTE AND MUNISING WHERE MODELS INDICATE LOW-LEVEL CONVERGENCE WILL BE MAXIMIZED. && .LONG TERM (TUESDAY NIGHT THROUGH MONDAY)... MAIN FORECAST ISSUE IS AMOUNT OF SNOWFALL TUESDAY NIGHT THROUGH THURSDAY. SEVERAL MODELS ARE BEGINNING TO SHOW SIGNS OF A DOMINANT BAND FORMING NEAR MUNISING TUESDAY EVENING AND PERSISTING INTO WEDNESDAY MORNING. REGIONAL GEM...NAM...AND LOCAL HI-RES WRF-ARW ALL SHOW THIS FEATURE...ALTHOUGH IT ISN`T PRESENT IN THE GFS. WILL GO AHEAD AND INCREASE QPF/SNOW AMOUNTS IN THIS GENERAL AREA...AND IF THIS FEATURE CONTINUES TO APPEAR IN FUTURE MODEL RUNS...A HEADLINE MAY BE NEEDED FOR ALGER COUNTY. ACROSS THE REST OF THE LAKE SUPERIOR SHORELINE...NORTHWEST WINDS WILL RESULT IN LIGHT LES CONTINUING FROM TUESDAY NIGHT THROUGH THURSDAY MORNING. INVERSION HEIGHTS WILL REMAIN BELOW 5000 FT...ALTHOUGH ALMOST THE ENTIRE INVERSION LIES WITHIN THE FAVORABLE DENDRITIC GROWTH ZONE. LAKE EFFECT WILL COME TO AN END DURING THE DAY ON THURSDAY AS A RIDGE BEGINS TO BUILD INTO THE REGION AND WINDS BACK TO THE SOUTHWEST. THERE IS THE POTENTIAL FOR A SHORT PERIOD OF LAKE EFFECT SNOW ALONG THE LAKE MICHIGAN SHORELINE WITH S-SW WINDS AND 850MB TEMPERATURES AROUND -15C THURSDAY AFTERNOON...ALTHOUGH CONFIDENCE IN TEMPERATURES AND WINDS MATCHING AT THE SAME TIME PERIOD IS NOT HIGH ENOUGH TO ADD ANY POPS AT THIS TIME. CONFIDENCE THROUGH EXTENDED PERIOD DECREASES AS MODEL SOLUTIONS BEGIN TO DIVERGE BY SUNDAY. MODELS ARE IN GENERAL AGREEMENT THAT A LOW WILL MOVE FROM THE MN ARROWHEAD ACROSS LAKE SUPERIOR DURING THE DAY ON FRIDAY...WITH HIGH PRESSURE BUILDING IN BEHIND THE LOW FOR SATURDAY. ECMWF WAS THE PREFERRED MODEL THROUGH THIS PORTION OF THE PERIOD...AND IS THEN BLENDED WITH 00Z NCEP ENSEMBLE MEAN AND 00Z CANADIAN GLOBAL SOLUTIONS. A WEAK LOW PRESSURE SYSTEM SHOULD THEN PUSH THROUGH THE GREAT LAKES BY MONDAY MORNING. RELIED HEAVILY ON HPC GUIDANCE FOR DAYS 6 AND 7 WHEN MODELS WERE DIVERGENT. MAIN CHANGE THAT USING HPC GUIDANCE CAUSED WAS AN ADDITION OF CHANCE POPS TO SUNDAY AND MONDAY WITH THE LOW ENTERING THE AREA. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... INFLUX OF DRIER AIR IN NRN MN/SRN ONTARIO AS SHOWN ON RECENT TAMDAR SDNGS FM INL/YQT NOW BREAKING UP THE CLD OVER NRN LK SUP WL RESULT IN PREDOMINANT VFR CONDITIONS AT CMX THRU THIS EVNG WITH UNFVRBL N FLOW. THE VSBY WL ALSO IMPROVE AT SAW...BUT EXPECT SC MVFR CIGS TO LINGER FOR THE MOST PART WITH LONGER FETCH AND FVRBL UPSLOPE NLY FLOW. WITH WEAKENING DRY ADVECTION LATER TNGT...SUSPECT MVFR CIG WL DVLP AT CMX WHILE STEADIER SHSN THAT RESTRICT VSBY TO MVFR RANGE COMMENCE AT SAW. BEST CHC FOR MORE FREQUENT SHSN AND LOWER VSBY... MVFR AT CMX/IFR AT SAW...WL BE TUE MRNG INTO THE AFTN WHEN DIGGING SHRTWV DRAGS COLDER LLVL AIR INTO THE UPR LKS AND INVRN BASE LIFTS TO 5-6K FT. ARRIVAL OF THE COLDER AIR WL ALSO RESULT IN GUSTY WINDS AT TIMES. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT NORTHERLY WINDS TO DOMINATE THROUGH MIDWEEK. AN INCREASING PRESSURE GRADIENT BETWEEN LOW PRESSURE MOVING INTO THE OHIO VALLEY AND HIGH PRESSURE OVER THE PLAINS WILL RESULT IN WINDS TO 30 KT FROM TUE AFTERNOON THROUGH TUE NIGHT. HEAVY FREEZING SPRAY IS ALSO EXPECTED TUE INTO WED AS COLDER AIR MOVES IN. AS THE LOW MOVES E ON WED THE NORTHERLY GRADIENT WILL SLACKEN AS WINDS QUICKLY DIE DOWN BLO 20 KT BY LATE WED. SRLY WINDS WILL INCREASE TO 25 TO 30 KT BY LATE THU AND THU NIGHT AS ANOTHER CLIPPER SYSTEM DIVES INTO THE NRN PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING FROM 7 AM TUESDAY TO 7 PM EST WEDNESDAY FOR LMZ248-250. && $$ UPDATE...KC SHORT TERM...VOSS LONG TERM...TAG MARINE...VOSS AVIATION...KC mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 625 PM EST MON FEB 25 2008 UPDATED FOR 00Z TAF ISSUANCE .SYNOPSIS... SOMEWHAT AMPLIFIED PATTERN OVER NORTH AMERICA AS NOTED ON WATER VAPOR LOOP AND RUC ANALYSIS. MEAN RIDGE IS OVER THE WEST COAST WITH A BROAD TROF OVER THE ERN 2/3RD OF CANADA AND UPR GREAT LAKES AND NE U.S. SRN STREAM SYSTEM MOVING THROUGH THE CENTRAL PLAINS IS PROJECTED TO MOVE THROUGH THE OHIO VALLEY TONIGHT AND TUE AND WILL NOT A SYNOPTIC IMPACT OUR UPR MI WX EXCEPT TO TIGHTEN NRLY GRADIENT OVER THE REGION ON BACK SIDE OF LOW. COLDER AIR MOVING IN LATE TONIGHT AND TUESDAY WITH ADVANCE OF SHORTWAVE FROM SRN MANITOBA WILL HELP GENERATE LES FOR AREAS DOWNSTREAM OF LAKE SUPERIOR IN NRLY FLOW. .SHORT TERM (TONIGHT AND TUESDAY)... BIG QUESTION TONIGHT WILL BE HOW LONG WILL IT TAKE FOR LES BANDS TO DEVELOP AS COLDEST AIR DOESN`T MOVE ACROSS THE AREA UNTIL LATE TONIGHT WITH ARRIVAL OF CLIPPER SHORTWAVE OVER SRN MANITOBA. INITIALLY OVER LAKE SUPERIOR THIS EVENING 850 MB TEMPS ARE FCST TO BE -10C TO -11C WHICH MAY NOT BE COLD ENOUGH TO GENERATE LES. GIVEN MARGINALLY COLD TEMPS FOR EVEN ICE IN THE CLOUDS...HAVE DECIDED TO THROW IN SOME PATCHY FZDZ FOR WEST AND NCNTRL COUNTIES IN NRLY UPSLOPE FLOW. WITH APPROACH OF CLIPPER SHORTWAVE OVERNIGHT...MODELS THEN SHOW 850 MB TEMPS LOWERING TO -16 TO -18 LATE TONIGHT WHICH SHOULD HELP GENERATE SOME LES. SO GIVEN THE SLOWER ADVANCE OF COLD AIR UNTIL LATE TONIGHT GENERALLY TRIMMED BACK ACCUMS TONIGHT TO INCH OR LESS OVER THE FAVORED NRLY UPSLOPE AREAS IN WEST AND NCNTRL ZONES...BUT KEPT IN LIKELY POPS FOR THE OVERNIGHT IN THESE COUNTIES. BY TUE...THE COLDEST AIR IS OVER THE UPR GREAT LAKES WITH 850 MB TEMPS LOWERING TO AROUND -19C. HOWEVER...SFC-850 MB FLOW IS ALSO BECOMING SHARPLY ANTICYCLONIC BY THIS TIME WITH DRY AIR AT LOW-LEVELS ADVECTING IN FROM ONTARIO. THE DRY AIR COMBINED WITH INCREASED SUN ANGLE/DIURNAL HEATING THIS TIME OF YEAR...MAY DISRUPT LES BANDS A BIT DURING THE DAY. FOR THESE REASONS ALSO TRIMMED BACK ACCUMS TO AROUND AN INCH FOR WEST AND CENTRAL ZONES IN UPSLOPE NRLY FLOW. THERE COULD BE SOME LOCALLY HIGHER AMOUNTS (AROUND 2 INCHES) BETWEEN MARQUETTE AND MUNISING WHERE MODELS INDICATE LOW-LEVEL CONVERGENCE WILL BE MAXIMIZED. && .LONG TERM (TUESDAY NIGHT THROUGH MONDAY)... MAIN FORECAST ISSUE IS AMOUNT OF SNOWFALL TUESDAY NIGHT THROUGH THURSDAY. SEVERAL MODELS ARE BEGINNING TO SHOW SIGNS OF A DOMINANT BAND FORMING NEAR MUNISING TUESDAY EVENING AND PERSISTING INTO WEDNESDAY MORNING. REGIONAL GEM...NAM...AND LOCAL HI-RES WRF-ARW ALL SHOW THIS FEATURE...ALTHOUGH IT ISN`T PRESENT IN THE GFS. WILL GO AHEAD AND INCREASE QPF/SNOW AMOUNTS IN THIS GENERAL AREA...AND IF THIS FEATURE CONTINUES TO APPEAR IN FUTURE MODEL RUNS...A HEADLINE MAY BE NEEDED FOR ALGER COUNTY. ACROSS THE REST OF THE LAKE SUPERIOR SHORELINE...NORTHWEST WINDS WILL RESULT IN LIGHT LES CONTINUING FROM TUESDAY NIGHT THROUGH THURSDAY MORNING. INVERSION HEIGHTS WILL REMAIN BELOW 5000 FT...ALTHOUGH ALMOST THE ENTIRE INVERSION LIES WITHIN THE FAVORABLE DENDRITIC GROWTH ZONE. LAKE EFFECT WILL COME TO AN END DURING THE DAY ON THURSDAY AS A RIDGE BEGINS TO BUILD INTO THE REGION AND WINDS BACK TO THE SOUTHWEST. THERE IS THE POTENTIAL FOR A SHORT PERIOD OF LAKE EFFECT SNOW ALONG THE LAKE MICHIGAN SHORELINE WITH S-SW WINDS AND 850MB TEMPERATURES AROUND -15C THURSDAY AFTERNOON...ALTHOUGH CONFIDENCE IN TEMPERATURES AND WINDS MATCHING AT THE SAME TIME PERIOD IS NOT HIGH ENOUGH TO ADD ANY POPS AT THIS TIME. CONFIDENCE THROUGH EXTENDED PERIOD DECREASES AS MODEL SOLUTIONS BEGIN TO DIVERGE BY SUNDAY. MODELS ARE IN GENERAL AGREEMENT THAT A LOW WILL MOVE FROM THE MN ARROWHEAD ACROSS LAKE SUPERIOR DURING THE DAY ON FRIDAY...WITH HIGH PRESSURE BUILDING IN BEHIND THE LOW FOR SATURDAY. ECMWF WAS THE PREFERRED MODEL THROUGH THIS PORTION OF THE PERIOD...AND IS THEN BLENDED WITH 00Z NCEP ENSEMBLE MEAN AND 00Z CANADIAN GLOBAL SOLUTIONS. A WEAK LOW PRESSURE SYSTEM SHOULD THEN PUSH THROUGH THE GREAT LAKES BY MONDAY MORNING. RELIED HEAVILY ON HPC GUIDANCE FOR DAYS 6 AND 7 WHEN MODELS WERE DIVERGENT. MAIN CHANGE THAT USING HPC GUIDANCE CAUSED WAS AN ADDITION OF CHANCE POPS TO SUNDAY AND MONDAY WITH THE LOW ENTERING THE AREA. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... INFLUX OF DRIER AIR IN NRN MN/SRN ONTARIO AS SHOWN ON RECENT TAMDAR SDNGS FM INL/YQT NOW BREAKING UP THE CLD OVER NRN LK SUP WL RESULT IN PREDOMINANT VFR CONDITIONS AT CMX THRU THIS EVNG WITH UNFVRBL N FLOW. THE VSBY WL ALSO IMPROVE AT SAW...BUT EXPECT SC MVFR CIGS TO LINGER FOR THE MOST PART WITH LONGER FETCH AND FVRBL UPSLOPE NLY FLOW. WITH WEAKENING DRY ADVECTION LATER TNGT...SUSPECT MVFR CIG WL DVLP AT CMX WHILE STEADIER SHSN THAT RESTRICT VSBY TO MVFR RANGE COMMENCE AT SAW. BEST CHC FOR MORE FREQUENT SHSN AND LOWER VSBY... MVFR AT CMX/IFR AT SAW...WL BE TUE MRNG INTO THE AFTN WHEN DIGGING SHRTWV DRAGS COLDER LLVL AIR INTO THE UPR LKS AND INVRN BASE LIFTS TO 5-6K FT. ARRIVAL OF THE COLDER AIR WL ALSO RESULT IN GUSTY WINDS AT TIMES. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT NORTHERLY WINDS TO DOMINATE THROUGH MIDWEEK. AN INCREASING PRESSURE GRADIENT BETWEEN LOW PRESSURE MOVING INTO THE OHIO VALLEY AND HIGH PRESSURE OVER THE PLAINS WILL RESULT IN WINDS TO 30 KT FROM TUE AFTERNOON THROUGH TUE NIGHT. HEAVY FREEZING SPRAY IS ALSO EXPECTED TUE INTO WED AS COLDER AIR MOVES IN. AS THE LOW MOVES E ON WED THE NORTHERLY GRADIENT WILL SLACKEN AS WINDS QUICKLY DIE DOWN BLO 20 KT BY LATE WED. SRLY WINDS WILL INCREASE TO 25 TO 30 KT BY LATE THU AND THU NIGHT AS ANOTHER CLIPPER SYSTEM DIVES INTO THE NRN PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...VOSS LONG TERM...TAG MARINE...VOSS AVIATION...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 420 PM EST MON FEB 25 2008 .SYNOPSIS... SOMEWHAT AMPLIFIED PATTERN OVER NORTH AMERICA AS NOTED ON WATER VAPOR LOOP AND RUC ANALYSIS. MEAN RIDGE IS OVER THE WEST COAST WITH A BROAD TROF OVER THE ERN 2/3RD OF CANADA AND UPR GREAT LAKES AND NE U.S. SRN STREAM SYSTEM MOVING THROUGH THE CENTRAL PLAINS IS PROJECTED TO MOVE THROUGH THE OHIO VALLEY TONIGHT AND TUE AND WILL NOT A SYNOPTIC IMPACT OUR UPR MI WX EXCEPT TO TIGHTEN NRLY GRADIENT OVER THE REGION ON BACK SIDE OF LOW. COLDER AIR MOVING IN LATE TONIGHT AND TUESDAY WITH ADVANCE OF SHORTWAVE FROM SRN MANITOBA WILL HELP GENERATE LES FOR AREAS DOWNSTREAM OF LAKE SUPERIOR IN NRLY FLOW. .SHORT TERM (TONIGHT AND TUESDAY)... BIG QUESTION TONIGHT WILL BE HOW LONG WILL IT TAKE FOR LES BANDS TO DEVELOP AS COLDEST AIR DOESN`T MOVE ACROSS THE AREA UNTIL LATE TONIGHT WITH ARRIVAL OF CLIPPER SHORTWAVE OVER SRN MANITOBA. INITIALLY OVER LAKE SUPERIOR THIS EVENING 850 MB TEMPS ARE FCST TO BE -10C TO -11C WHICH MAY NOT BE COLD ENOUGH TO GENERATE LES. GIVEN MARGINALLY COLD TEMPS FOR EVEN ICE IN THE CLOUDS...HAVE DECIDED TO THROW IN SOME PATCHY FZDZ FOR WEST AND NCNTRL COUNTIES IN NRLY UPSLOPE FLOW. WITH APPROACH OF CLIPPER SHORTWAVE OVERNIGHT...MODELS THEN SHOW 850 MB TEMPS LOWERING TO -16 TO -18 LATE TONIGHT WHICH SHOULD HELP GENERATE SOME LES. SO GIVEN THE SLOWER ADVANCE OF COLD AIR UNTIL LATE TONIGHT GENERALLY TRIMMED BACK ACCUMS TONIGHT TO INCH OR LESS OVER THE FAVORED NRLY UPSLOPE AREAS IN WEST AND NCNTRL ZONES...BUT KEPT IN LIKELY POPS FOR THE OVERNIGHT IN THESE COUNTIES. BY TUE...THE COLDEST AIR IS OVER THE UPR GREAT LAKES WITH 850 MB TEMPS LOWERING TO AROUND -19C. HOWEVER...SFC-850 MB FLOW IS ALSO BECOMING SHARPLY ANTICYCLONIC BY THIS TIME WITH DRY AIR AT LOW-LEVELS ADVECTING IN FROM ONTARIO. THE DRY AIR COMBINED WITH INCREASED SUN ANGLE/DIURNAL HEATING THIS TIME OF YEAR...MAY DISRUPT LES BANDS A BIT DURING THE DAY. FOR THESE REASONS ALSO TRIMMED BACK ACCUMS TO AROUND AN INCH FOR WEST AND CENTRAL ZONES IN UPSLOPE NRLY FLOW. THERE COULD BE SOME LOCALLY HIGHER AMOUNTS (AROUND 2 INCHES) BETWEEN MARQUETTE AND MUNISING WHERE MODELS INDICATE LOW-LEVEL CONVERGENCE WILL BE MAXIMIZED. && .LONG TERM (TUESDAY NIGHT THROUGH MONDAY)... MAIN FORECAST ISSUE IS AMOUNT OF SNOWFALL TUESDAY NIGHT THROUGH THURSDAY. SEVERAL MODELS ARE BEGINNING TO SHOW SIGNS OF A DOMINANT BAND FORMING NEAR MUNISING TUESDAY EVENING AND PERSISTING INTO WEDNESDAY MORNING. REGIONAL GEM...NAM...AND LOCAL HI-RES WRF-ARW ALL SHOW THIS FEATURE...ALTHOUGH IT ISN`T PRESENT IN THE GFS. WILL GO AHEAD AND INCREASE QPF/SNOW AMOUNTS IN THIS GENERAL AREA...AND IF THIS FEATURE CONTINUES TO APPEAR IN FUTURE MODEL RUNS...A HEADLINE MAY BE NEEDED FOR ALGER COUNTY. ACROSS THE REST OF THE LAKE SUPERIOR SHORELINE...NORTHWEST WINDS WILL RESULT IN LIGHT LES CONTINUING FROM TUESDAY NIGHT THROUGH THURSDAY MORNING. INVERSION HEIGHTS WILL REMAIN BELOW 5000 FT...ALTHOUGH ALMOST THE ENTIRE INVERSION LIES WITHIN THE FAVORABLE DENDRITIC GROWTH ZONE. LAKE EFFECT WILL COME TO AN END DURING THE DAY ON THURSDAY AS A RIDGE BEGINS TO BUILD INTO THE REGION AND WINDS BACK TO THE SOUTHWEST. THERE IS THE POTENTIAL FOR A SHORT PERIOD OF LAKE EFFECT SNOW ALONG THE LAKE MICHIGAN SHORELINE WITH S-SW WINDS AND 850MB TEMPERATURES AROUND -15C THURSDAY AFTERNOON...ALTHOUGH CONFIDENCE IN TEMPERATURES AND WINDS MATCHING AT THE SAME TIME PERIOD IS NOT HIGH ENOUGH TO ADD ANY POPS AT THIS TIME. CONFIDENCE THROUGH EXTENDED PERIOD DECREASES AS MODEL SOLUTIONS BEGIN TO DIVERGE BY SUNDAY. MODELS ARE IN GENERAL AGREEMENT THAT A LOW WILL MOVE FROM THE MN ARROWHEAD ACROSS LAKE SUPERIOR DURING THE DAY ON FRIDAY...WITH HIGH PRESSURE BUILDING IN BEHIND THE LOW FOR SATURDAY. ECMWF WAS THE PREFERRED MODEL THROUGH THIS PORTION OF THE PERIOD...AND IS THEN BLENDED WITH 00Z NCEP ENSEMBLE MEAN AND 00Z CANADIAN GLOBAL SOLUTIONS. A WEAK LOW PRESSURE SYSTEM SHOULD THEN PUSH THROUGH THE GREAT LAKES BY MONDAY MORNING. RELIED HEAVILY ON HPC GUIDANCE FOR DAYS 6 AND 7 WHEN MODELS WERE DIVERGENT. MAIN CHANGE THAT USING HPC GUIDANCE CAUSED WAS AN ADDITION OF CHANCE POPS TO SUNDAY AND MONDAY WITH THE LOW ENTERING THE AREA. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... THE FRONT IS THROUGH THE AREA...AND WINDS HAVE TURNED NORTH-NORTHEAST. THIS HAS ALLOWED THE FOG TO IMPROVE...HOWEVER THE CIGS REMAIN AT OR NEAR IFR. AT SAW...THE NORTHERLY WINDS MAY ALLOW FOR SOME WEAK UPSLOPE TYPE SNOW TO DEVELOP THIS AFTERNOON BUT NOTHING OF SIGNIFICANCE AND CIGS WILL LIKELY STAY MVFR. COULD SEE SOME BRIEF IFR VSBYS LATER THIS AFTERNOON ESPECIALLY IF THERE IS SOME BR MIXED IN WITH ANY LIGHT SNOW. MVFR CONDITIONS WILL CONTINUE THRU TUESDAY. AS FOR CMX...THE IFR CONDITIONS CURRENTLY OCCURRING IN THE NE FLOW SHOULD IMPROVE TO MVFR DURING THE AFTERNOON AS THE WINDS SHIFT NORTH. WITH THE WINDS STAYING N-NW TONIGHT INTO TUE...CONDITIONS WILL NOT BE FAVORABLE FOR IFR VSBYS OR CIGS AT CMX. AS THE OH VLY LOW DEEPENS TONIGHT INTO TUE...WINDS WILL BECOME GUSTY AT BOTH SITES ON TUESDAY MORNING. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT NORTHERLY WINDS TO DOMINATE THROUGH MIDWEEK. AN INCREASING PRESSURE GRADIENT BETWEEN LOW PRESSURE MOVING INTO THE OHIO VALLEY AND HIGH PRESSURE OVER THE PLAINS WILL RESULT IN WINDS TO 30 KT FROM TUE AFTERNOON THROUGH TUE NIGHT. HEAVY FREEZING SPRAY IS ALSO EXPECTED TUE INTO WED AS COLDER AIR MOVES IN. AS THE LOW MOVES E ON WED THE NORTHERLY GRADIENT WILL SLACKEN AS WINDS QUICKLY DIE DOWN BLO 20 KT BY LATE WED. SRLY WINDS WILL INCREASE TO 25 TO 30 KT BY LATE THU AND THU NIGHT AS ANOTHER CLIPPER SYSTEM DIVES INTO THE NRN PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...VOSS LONG TERM...TAG MARINE...VOSS AVIATION...MRD mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1045 AM EST MON FEB 25 2008 UPDATED FOR 18Z AVIATION. .UPDATE... NO MAJOR CHANGES ARE PLANNED FOR THE UPDATE. LATEST SURFACE ANALYSIS SUGGESTS THAT THE SURFACE FRONT IS THROUGH MUCH OF WESTERN AND CENTRAL UPPER MICHIGAN. COLD ADVECTION BEHIND THE FRONT IS QUITE WEAK INITIALLY...SO TEMPS SHOULD NOT SUFFER TOO MUCH DESPITE THE AREA BEING POST FRONTAL. CONFLUENT FLOW ALOFT WILL LIKELY KEEP WIDESPREAD SYNOPTIC CLOUDS OUT OF THE PICTURE...HOWEVER INCREASING UPSLOPE FLOW THIS AFTERNOON WILL ALLOW FOR MORE CLOUDINESS ESPECIALLY NEAR LAKE SUPERIOR AS THE DAY GOES ON. IN ADDITION...THE NAM SUGGESTS THAT THE LOWER CLOUDS WILL AFFECT INLAND AREAS THIS AFTERNOON. WITH THAT IN MIND...WILL CONTINUE WITH A MOSTLY CLOUDY FORECAST ALTHOUGH THERE WILL BE SOME SUNSHINE ESPECIALLY THIS MORNING. THE FOG AND LOWER CLOUDS ARE PLAYING HAVOC ON TEMPS WITH SOME AREAS ALREADY IN THE UPPER 20S/LOWER 30S WITH OTHERS STILL IN THE TEENS. THE LEAST CLOUDS AT THIS TIME ARE IN INLAND CENTRAL AND SOUTHERN UPPER MICHIGAN AND THESE SITES WOULD SEEM TO HAVE THE BEST CHANCE TO WARM INTO THE MID 30S TODAY. IN FACT...MNN IS ALREADY IN THE LOWER 30S. WILL NOT TWEAK TEMPS MUCH TODAY WITH SOUTHERN UPPER MICHIGAN LIKELY IN THE MID 30S WITH OTHER AREAS AROUND 30S OR THE LOWER 30S. WITH INCREASING UPSLOPE FLOW...WILL KEEP THE SLIGHT CHANCE POPS ACROSS THE WEST...ALTHOUGH IN REALITY THE BEST CHANCE FOR LAKE EFFECT SNOW WILL HAVE TO WAIT UNTIL TONIGHT WHEN THE COLDER AIR MOVES INTO THE REGION. GRIDDED AND ZFP UPDATE OUT BY 11 AM. && .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR SNOW TONIGHT AND TUESDAY. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN CANADA AND A STEEP RIDGE OVER THE CANADIAN ROCKIES. A WEAK SHORTWAVE STRETCHES FROM SOUTHERN MANITOBA THROUGH MINNESOTA TO SOUTHERN WISCONSIN. ANOTHER SHORTWAVE IS OVER NORTHERN SASKATCHEWAN. SURFACE ANALYSIS DEPICTS A LARGE HIGH BLANKETING MUCH OF THE SOUTHEASTERN STATES...A LOW OVER THE CENTRAL PLAINS CONNECTS VIA A WEAK SURFACE TROUGH TO ANOTHER LOW OVER LAKE SUPERIOR. A COLD FRONT EXTENDS FROM WINNIPEG ACROSS ONTARIO...JUST NORTH OF LAKE SUPERIOR...TO A LOW IN THE CANADIAN MARITIME. PATCHY FOG IS OVER THE UPPER GREAT LAKES. MODELS ARE IN A FAIRLY GOOD AGREEMENT THROUGH DAY 4. A PORTION OF THE LONGWAVE TROUGH WILL DEEPEN OVER CENTRAL CANADA TODAY. A WEAK LOW WILL START TO DEVELOP OVER IOWA IN THIS FLOW. A WEAK SHORTWAVE WILL ADVANCE ACROSS THE FORECAST AREA. THE SURFACE LOW WILL PROCEED INTO CENTRAL MISSOURI. THE COLD FRONT TO THE NORTH OF LAKE SUPERIOR WILL SETTLE OVER THE FORECAST AREA. GUIDANCE SUGGEST THAT THE LOW LEVELS WILL REMAIN FAIRLY DRY. HOWEVER...WITH THE SNOW MELT OVER THE FORECAST AREA ON SUNDAY AND EXPECTED MORE MELTING TODAY...THERE MAY BE ENOUGH TO GENERATE SOME SNOWS WITH THE APPROACH OF THE FRONT. THUS WILL KEEP IN A SLIGHT MENTION OF SNOW TODAY AND AREAS OF FOG EARLY. THE WINDS WILL VEER NORTH FOLLOWING THE FROPA BRINGING COOLER AIR INTO THE AREA. THE TROUGH DEVELOPING OVER CENTRAL CANADA WILL CONTINUE TO DEEPEN OVER THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE THE RIDGE OVER THE ROCKIES BUILDS. THE SURFACE LOW OVER MISSOURI WILL PROCEED TO SOUTHERN OHIO AS THE COLD FRONT OVER THE FORECAST AREA SHIFT INTO LOWER NORTHERN LOWER MICHIGAN. A RIDGE WILL DEVELOP OVER NORTHERN HIGH PLAINS WHILE ANOTHER LOW DEVELOPS OVER NORTHERN ALBERTA. THE LAKE-850MB DELTA-T`S WILL INCREASE TO AROUND 13C. THIS WOULD SUPPORT THE START OF SOME ENHANCE LES OVER THE NORTHERN PART OF THE FORECAST AREA. MODIS SATELLITE VISIBLE IMAGERY SHOWING LARGE AREAS OF ICE ON LAKE SUPERIOR WHICH WILL LIMIT LES DEVELOPMENT. THUS WILL KEEP ONLY A CHANCE OF LES GOING OVER AREAS PRONE TO LES WITH NORTHWEST FLOW. THE LONGWAVE TROUGH WILL DEEPEN OVER THE FORECAST AREA ON TUESDAY. THE DELTA-T`S WILL INCREASE TO AROUND 21C OVER LAKE SUPERIOR. LOW LEVEL MOISTURE ALONG WITH THE INCREASE 850-500MB Q-VECTOR CONVERGENCE OVER THE AREA...AND LOW LEVEL INSTABILITY WILL SUPPORT INCREASED LES OVER THE NORTHERN PART OF THE AREA. ICE OVER THE LAKE WILL CONTINUE TO LIMIT FETCH TIME OVER THE LAKE. SO LES WILL BE MORE WIDESPREAD WITH A ONLY FEW INCHES POSSIBLE. THE LONGWAVE TROUGH WILL TREK INTO EASTERN ONTARIO TUESDAY NIGHT. THE DELTA-T`S WILL REMAIN CONSTANT OVER THE LAKE AROUND 21C. 925MB WINDS SHOWING LOW LEVEL CONVERGENCE OVER THE LAKE WILL CONTINUE...KEEPING LES IN THE GRID THROUGH TUESDAY NIGHT. ICE AND LIMITED LOW LEVEL MOISTURE WILL DECREASE THE CHANCES OF HEAVY LES. THESE SAME CONDITIONS WILL CONTINUE THROUGH WEDNESDAY. ONLY THING IS ON WEDNESDAY THE SURFACE HIGH WILL MOVE OUT OF THE PLAINS INTO THE UPPER GREAT LAKES CASUING THE WINDS TO DIMINISH AND START BACKING WEST. AS THE SURFACE RIDGE MOVES OVER THE FORECAST AREA WEDNESDAY NIGHT. THE LES WILL DIMINISH SIGNIFICANTLY DUE TO LOST OF A NORTHWEST FLOW AND WARM AIR ADVECTION BEHIND WEST OF THE RIDGE WILL DIMINISH THE DELTA-T`S. ON THURSDAY...AS THE RIDGE TRACKS INTO WESTERN QUEBEC... A SOUTHWEST FLOW BEHIND THE RIDGE WILL KILL OFF ANY REMAINING LES. THE NEXT SYSTEM WILL DROP OUT OF ALBERTA AND INTO THE NORTHERN MINNESOTA ON THURSDAY TAKING AIM AT THE GREAT LAKES REGION. THE LOW WILL MOVE INTO THE UPPER GREAT LAKES REGION THURSDAY NIGHT AND FRIDAY. THE ECMWF PLACES THE LOW NORTH OF LAKE SUPERIOR WHEREAS THE GFS PREFERS A SOLUTION THAT BRINGS THE LOW OVER THE U.P. IN EITHER CASE THERE WILL BE CHANCES OF SNOW WITH THIS SYSTEM. HOW MUCH AND THE STRENGTH OF THE WINDS WILL DEPEND ON THE WHICH SOLUTION PANS OUT. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... THE FRONT IS THROUGH THE AREA...AND WINDS HAVE TURNED NORTH-NORTHEAST. THIS HAS ALLOWED THE FOG TO IMPROVE...HOWEVER THE CIGS REMAIN AT OR NEAR IFR. AT SAW...THE NORTHERLY WINDS MAY ALLOW FOR SOME WEAK UPSLOPE TYPE SNOW TO DEVELOP THIS AFTERNOON BUT NOTHING OF SIGNIFICANCE AND CIGS WILL LIKELY STAY MVFR. COULD SEE SOME BRIEF IFR VSBYS LATER THIS AFTERNOON ESPECIALLY IF THERE IS SOME BR MIXED IN WITH ANY LIGHT SNOW. MVFR CONDITIONS WILL CONTINUE THRU TUESDAY. AS FOR CMX...THE IFR CONDITIONS CURRENTLY OCCURRING IN THE NE FLOW SHOULD IMPROVE TO MVFR DURING THE AFTERNOON AS THE WINDS SHIFT NORTH. WITH THE WINDS STAYING N-NW TONIGHT INTO TUE...CONDITIONS WILL NOT BE FAVORABLE FOR IFR VSBYS OR CIGS AT CMX. AS THE OH VLY LOW DEEPENS TONIGHT INTO TUE...WINDS WILL BECOME GUSTY AT BOTH SITES ON TUESDAY MORNING. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT WINDS OVER SOUTHERN LAKE SUPERIOR TO VEER NORTHERLY TODAY AS A TROUGH SLIDES SOUTH THROUGH THE AREA. NORTH WINDS WILL THEN DOMINATE THROUGH MIDWEEK. AN INCREASING PRESSURE GRADIENT BETWEEN LOW PRESSURE MOVING INTO THE OHIO VALLEY AND HIGH PRESSURE OVER THE PLAINS AND NORTHERN ONTARIO WILL RESULT IN WINDS TO 30 KT FROM TUE AFTERNOON THROUGH TUE NIGHT. HEAVY FREEZING SPRAY IS ALSO EXPECTED TUE INTO WED AS COLDER AIR MOVES IN. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...MRD DISCUSSION...DLG MARINE...JLB AVIATION...MRD mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 645 AM EST MON FEB 25 2008 UPDATED FOR 12Z TAF DISCUSSION .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR SNOW TONIGHT AND TUESDAY. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN CANADA AND A STEEP RIDGE OVER THE CANADIAN ROCKIES. A WEAK SHORTWAVE STRETCHES FROM SOUTHERN MANITOBA THROUGH MINNESOTA TO SOUTHERN WISCONSIN. ANOTHER SHORTWAVE IS OVER NORTHERN SASKATCHEWAN. SURFACE ANALYSIS DEPICTS A LARGE HIGH BLANKETING MUCH OF THE SOUTHEASTERN STATES...A LOW OVER THE CENTRAL PLAINS CONNECTS VIA A WEAK SURFACE TROUGH TO ANOTHER LOW OVER LAKE SUPERIOR. A COLD FRONT EXTENDS FROM WINNIPEG ACROSS ONTARIO...JUST NORTH OF LAKE SUPERIOR...TO A LOW IN THE CANADIAN MARITIME. PATCHY FOG IS OVER THE UPPER GREAT LAKES. MODELS ARE IN A FAIRLY GOOD AGREEMENT THROUGH DAY 4. A PORTION OF THE LONGWAVE TROUGH WILL DEEPEN OVER CENTRAL CANADA TODAY. A WEAK LOW WILL START TO DEVELOP OVER IOWA IN THIS FLOW. A WEAK SHORTWAVE WILL ADVANCE ACROSS THE FORECAST AREA. THE SURFACE LOW WILL PROCEED INTO CENTRAL MISSOURI. THE COLD FRONT TO THE NORTH OF LAKE SUPERIOR WILL SETTLE OVER THE FORECAST AREA. GUIDANCE SUGGEST THAT THE LOW LEVELS WILL REMAIN FAIRLY DRY. HOWEVER...WITH THE SNOW MELT OVER THE FORECAST AREA ON SUNDAY AND EXPECTED MORE MELTING TODAY...THERE MAY BE ENOUGH TO GENERATE SOME SNOWS WITH THE APPROACH OF THE FRONT. THUS WILL KEEP IN A SLIGHT MENTION OF SNOW TODAY AND AREAS OF FOG EARLY. THE WINDS WILL VEER NORTH FOLLOWING THE FROPA BRINGING COOLER AIR INTO THE AREA. THE TROUGH DEVELOPING OVER CENTRAL CANADA WILL CONTINUE TO DEEPEN OVER THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE THE RIDGE OVER THE ROCKIES BUILDS. THE SURFACE LOW OVER MISSOURI WILL PROCEED TO SOUTHERN OHIO AS THE COLD FRONT OVER THE FORECAST AREA SHIFT INTO LOWER NORTHERN LOWER MICHIGAN. A RIDGE WILL DEVELOP OVER NORTHERN HIGH PLAINS WHILE ANOTHER LOW DEVELOPS OVER NORTHERN ALBERTA. THE LAKE-850MB DELTA-T`S WILL INCREASE TO AROUND 13C. THIS WOULD SUPPORT THE START OF SOME ENHANCE LES OVER THE NORTHERN PART OF THE FORECAST AREA. MODIS SATELLITE VISIBLE IMAGERY SHOWING LARGE AREAS OF ICE ON LAKE SUPERIOR WHICH WILL LIMIT LES DEVELOPMENT. THUS WILL KEEP ONLY A CHANCE OF LES GOING OVER AREAS PRONE TO LES WITH NORTHWEST FLOW. THE LONGWAVE TROUGH WILL DEEPEN OVER THE FORECAST AREA ON TUESDAY. THE DELTA-T`S WILL INCREASE TO AROUND 21C OVER LAKE SUPERIOR. LOW LEVEL MOISTURE ALONG WITH THE INCREASE 850-500MB Q-VECTOR CONVERGENCE OVER THE AREA...AND LOW LEVEL INSTABILITY WILL SUPPORT INCREASED LES OVER THE NORTHERN PART OF THE AREA. ICE OVER THE LAKE WILL CONTINUE TO LIMIT FETCH TIME OVER THE LAKE. SO LES WILL BE MORE WIDESPREAD WITH A ONLY FEW INCHES POSSIBLE. THE LONGWAVE TROUGH WILL TREK INTO EASTERN ONTARIO TUESDAY NIGHT. THE DELTA-T`S WILL REMAIN CONSTANT OVER THE LAKE AROUND 21C. 925MB WINDS SHOWING LOW LEVEL CONVERGENCE OVER THE LAKE WILL CONTINUE...KEEPING LES IN THE GRID THROUGH TUESDAY NIGHT. ICE AND LIMITED LOW LEVEL MOISTURE WILL DECREASE THE CHANCES OF HEAVY LES. THESE SAME CONDITIONS WILL CONTINUE THROUGH WEDNESDAY. ONLY THING IS ON WEDNESDAY THE SURFACE HIGH WILL MOVE OUT OF THE PLAINS INTO THE UPPER GREAT LAKES CASUING THE WINDS TO DIMINISH AND START BACKING WEST. AS THE SURFACE RIDGE MOVES OVER THE FORECAST AREA WEDNESDAY NIGHT. THE LES WILL DIMINISH SIGNIFICANTLY DUE TO LOST OF A NORTHWEST FLOW AND WARM AIR ADVECTION BEHIND WEST OF THE RIDGE WILL DIMINISH THE DELTA-T`S. ON THURSDAY...AS THE RIDGE TRACKS INTO WESTERN QUEBEC... A SOUTHWEST FLOW BEHIND THE RIDGE WILL KILL OFF ANY REMAINING LES. THE NEXT SYSTEM WILL DROP OUT OF ALBERTA AND INTO THE NORTHERN MINNESOTA ON THURSDAY TAKING AIM AT THE GREAT LAKES REGION. THE LOW WILL MOVE INTO THE UPPER GREAT LAKES REGION THURSDAY NIGHT AND FRIDAY. THE ECMWF PLACES THE LOW NORTH OF LAKE SUPERIOR WHEREAS THE GFS PREFERS A SOLUTION THAT BRINGS THE LOW OVER THE U.P. IN EITHER CASE THERE WILL BE CHANCES OF SNOW WITH THIS SYSTEM. HOW MUCH AND THE STRENGTH OF THE WINDS WILL DEPEND ON THE WHICH SOLUTION PANS OUT. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... EXPECT LOW CLOUDS ASSOCIATED WITH AN APPROACHING COLD FRONT TO PERSIST AT KCMX THIS MORNING. A PERIOD OF LOW CLOUDS AND FOG AT KSAW SHOULD GIVE WAY TO AN MVFR SC DECK BY LATE THIS MORNING. EVENTUAL ARRIVAL OF DRIER AIR WILL LIKELY BREAK UP THE CLOUDS AT KCMX LATE TODAY... BUT NOT AT KSAW WHERE LONGER FETCH AND FAVORABLE UPSLOPE N FLOW WILL HELP MAINTAIN THE SC DECK FOR A LONGER TIME. LITTLE OR NO LES IS EXPECTED IMMEDIATELY BEHIND THE FROPA DUE TO MARGINAL COLD AIR AND LOW INVERSION BASE. ALTHOUGH COLDER AIR WILL GRADUALLY ARRIVE THIS EVENING...SO WILL DRIER AIR. SO EXPECT NO VSBY RESTRICTION EVEN AT KSAW WHERE FETCH/UPSLOPE MORE FVRBL. CAA WILL EVENTUALLY RESULT IN ENOUGH COOLING FOR SOME LIGHT LES OVERNIGHT WITH MVFR CIGS/VSBY POSSIBLE AT KSAW. NRLY FLOW WILL NOT FAVOR KCMX FOR LES. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT WINDS OVER SOUTHERN LAKE SUPERIOR TO VEER NORTHERLY TODAY AS A TROUGH SLIDES SOUTH THROUGH THE AREA. NORTH WINDS WILL THEN DOMINATE THROUGH MIDWEEK. AN INCREASING PRESSURE GRADIENT BETWEEN LOW PRESSURE MOVING INTO THE OHIO VALLEY AND HIGH PRESSURE OVER THE PLAINS AND NORTHERN ONTARIO WILL RESULT IN WINDS TO 30 KT FROM TUE AFTERNOON THROUGH TUE NIGHT. HEAVY FREEZING SPRAY IS ALSO EXPECTED TUE INTO WED AS COLDER AIR MOVES IN. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...DLG MARINE/AVIATION...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 425 AM EST MON FEB 25 2008 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR SNOW TONIGHT AND TUESDAY. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN CANADA AND A STEEP RIDGE OVER THE CANADIAN ROCKIES. A WEAK SHORTWAVE STRETCHES FROM SOUTHERN MANITOBA THROUGH MINNESOTA TO SOUTHERN WISCONSIN. ANOTHER SHORTWAVE IS OVER NORTHERN SASKATCHEWAN. SURFACE ANALYSIS DEPICTS A LARGE HIGH BLANKETING MUCH OF THE SOUTHEASTERN STATES...A LOW OVER THE CENTRAL PLAINS CONNECTS VIA A WEAK SURFACE TROUGH TO ANOTHER LOW OVER LAKE SUPERIOR. A COLD FRONT EXTENDS FROM WINNIPEG ACROSS ONTARIO...JUST NORTH OF LAKE SUPERIOR...TO A LOW IN THE CANADIAN MARITIME. PATCHY FOG IS OVER THE UPPER GREAT LAKES. MODELS ARE IN A FAIRLY GOOD AGREEMENT THROUGH DAY 4. A PORTION OF THE LONGWAVE TROUGH WILL DEEPEN OVER CENTRAL CANADA TODAY. A WEAK LOW WILL START TO DEVELOP OVER IOWA IN THIS FLOW. A WEAK SHORTWAVE WILL ADVANCE ACROSS THE FORECAST AREA. THE SURFACE LOW WILL PROCEED INTO CENTRAL MISSOURI. THE COLD FRONT TO THE NORTH OF LAKE SUPERIOR WILL SETTLE OVER THE FORECAST AREA. GUIDANCE SUGGEST THAT THE LOW LEVELS WILL REMAIN FAIRLY DRY. HOWEVER...WITH THE SNOW MELT OVER THE FORECAST AREA ON SUNDAY AND EXPECTED MORE MELTING TODAY...THERE MAY BE ENOUGH TO GENERATE SOME SNOWS WITH THE APPROACH OF THE FRONT. THUS WILL KEEP IN A SLIGHT MENTION OF SNOW TODAY AND AREAS OF FOG EARLY. THE WINDS WILL VEER NORTH FOLLOWING THE FROPA BRINGING COOLER AIR INTO THE AREA. THE TROUGH DEVELOPING OVER CENTRAL CANADA WILL CONTINUE TO DEEPEN OVER THE UPPER MISSISSIPPI RIVER VALLEY TONIGHT WHILE THE RIDGE OVER THE ROCKIES BUILDS. THE SURFACE LOW OVER MISSOURI WILL PROCEED TO SOUTHERN OHIO AS THE COLD FRONT OVER THE FORECAST AREA SHIFT INTO LOWER NORTHERN LOWER MICHIGAN. A RIDGE WILL DEVELOP OVER NORTHERN HIGH PLAINS WHILE ANOTHER LOW DEVELOPS OVER NORTHERN ALBERTA. THE LAKE-850MB DELTA-T`S WILL INCREASE TO AROUND 13C. THIS WOULD SUPPORT THE START OF SOME ENHANCE LES OVER THE NORTHERN PART OF THE FORECAST AREA. MODIS SATELLITE VISIBLE IMAGERY SHOWING LARGE AREAS OF ICE ON LAKE SUPERIOR WHICH WILL LIMIT LES DEVELOPMENT. THUS WILL KEEP ONLY A CHANCE OF LES GOING OVER AREAS PRONE TO LES WITH NORTHWEST FLOW. THE LONGWAVE TROUGH WILL DEEPEN OVER THE FORECAST AREA ON TUESDAY. THE DELTA-T`S WILL INCREASE TO AROUND 21C OVER LAKE SUPERIOR. LOW LEVEL MOISTURE ALONG WITH THE INCREASE 850-500MB Q-VECTOR CONVERGENCE OVER THE AREA...AND LOW LEVEL INSTABILITY WILL SUPPORT INCREASED LES OVER THE NORTHERN PART OF THE AREA. ICE OVER THE LAKE WILL CONTINUE TO LIMIT FETCH TIME OVER THE LAKE. SO LES WILL BE MORE WIDESPREAD WITH A ONLY FEW INCHES POSSIBLE. THE LONGWAVE TROUGH WILL TREK INTO EASTERN ONTARIO TUESDAY NIGHT. THE DELTA-T`S WILL REMAIN CONSTANT OVER THE LAKE AROUND 21C. 925MB WINDS SHOWING LOW LEVEL CONVERGENCE OVER THE LAKE WILL CONTINUE...KEEPING LES IN THE GRID THROUGH TUESDAY NIGHT. ICE AND LIMITED LOW LEVEL MOISTURE WILL DECREASE THE CHANCES OF HEAVY LES. THESE SAME CONDITIONS WILL CONTINUE THROUGH WEDNESDAY. ONLY THING IS ON WEDNESDAY THE SURFACE HIGH WILL MOVE OUT OF THE PLAINS INTO THE UPPER GREAT LAKES CASUING THE WINDS TO DIMINISH AND START BACKING WEST. AS THE SURFACE RIDGE MOVES OVER THE FORECAST AREA WEDNESDAY NIGHT. THE LES WILL DIMINISH SIGNIFICANTLY DUE TO LOST OF A NORTHWEST FLOW AND WARM AIR ADVECTION BEHIND WEST OF THE RIDGE WILL DIMINISH THE DELTA-T`S. ON THURSDAY...AS THE RIDGE TRACKS INTO WESTERN QUEBEC... A SOUTHWEST FLOW BEHIND THE RIDGE WILL KILL OFF ANY REMAINING LES. THE NEXT SYSTEM WILL DROP OUT OF ALBERTA AND INTO THE NORTHERN MINNESOTA ON THURSDAY TAKING AIM AT THE GREAT LAKES REGION. THE LOW WILL MOVE INTO THE UPPER GREAT LAKES REGION THURSDAY NIGHT AND FRIDAY. THE ECMWF PLACES THE LOW NORTH OF LAKE SUPERIOR WHEREAS THE GFS PREFERS A SOLUTION THAT BRINGS THE LOW OVER THE U.P. IN EITHER CASE THERE WILL BE CHANCES OF SNOW WITH THIS SYSTEM. HOW MUCH AND THE STRENGTH OF THE WINDS WILL DEPEND ON THE WHICH SOLUTION PANS OUT. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... ALTHOUGH NEAR SFC WIND IS SW...FLOW ABV THE SFC APPEARS TO BE MORE WNW...WHICH HAS PREVENTED LO CLD MASS TO THE SW FM ADVANCING TOWARD CMX/SAW. SO ALTHOUGH THERE MAY BE SOME SHALLOW FOG/MVFR VSBY THRU THE NGT...LOOK FOR CLR-PCLDY SKIES WITH LLVL FLOW LIKELY TO VEER SLOWLY THRU THE NGT IN ADVANCE OF COLD FNT TO THE N SINKING SLOWLY SWD. BEST CHC FOR LO CIG TO DVLP WL BE AT CMX...WHERE THIS WNW FLOW WL UPSLOPE. TIMING OF COLD FROPA FM THE N APPEARS TO BE A BIT SLOWER...SO PUSHED BACK ONSET OF PREDOMINANT MVFR CIGS ACCOMPANYING THE LLVL CAD/STEEPENING SFC-H85 LAPSE RATES BEHIND THIS FEATURE. EVENTUAL ARRIVAL OF DRIER AIR WL LIKELY BREAK UP THE CLD AT CMX LATE TDAY... BUT NOT AT SAW WHERE LONGER FETCH/FVRBL UPSLOPE N FLOW WL MAINTAIN SC DECK FOR A LONGER TIME. ANY LES IMMEDIATELY BEHIND THE FROPA WL BE MINIMAL DUE TO MARGINAL CHILL/LO INVRN BASE. ALTHOUGH COLDER AIR WL GRDLY ARRIVE THIS EVNG...SO WL DRIER AIR. SO EXPECT NO VSBY RESTRICTION EVEN AT SAW WHERE FETCH/UPSLOPE MORE FVRBL. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT WINDS OVER SOUTHERN LAKE SUPERIOR TO VEER NORTHERLY TODAY AS A TROUGH SLIDES SOUTH THROUGH THE AREA. NORTH WINDS WILL THEN DOMINATE THROUGH MIDWEEK. AN INCREASING PRESSURE GRADIENT BETWEEN LOW PRESSURE MOVING INTO THE OHIO VALLEY AND HIGH PRESSURE OVER THE PLAINS AND NORTHERN ONTARIO WILL RESULT IN WINDS TO 30 KT FROM TUE AFTERNOON THROUGH TUE NIGHT. HEAVY FREEZING SPRAY IS ALSO EXPECTED TUE INTO WED AS COLDER AIR MOVES IN. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...DLG MARINE...JLB AVIATION...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1227 PM EST SUN FEB 24 2008 UPDATED FOR 18Z TAF ISSUANCE/DISCUSSION .UPDATE... MADE SOME SIGNIFICANT CHANGES TO SKY GRIDS THROUGH DAY 2. IN THE NEAR TERM THIS WAS TO ACCOUNT FOR THE CLEAR SKY AND HAZE OVER MUCH OF THE AREA...AND FOG OVER NORTHERN WISCONSIN CREEPING SOUTHEASTWARD ACROSS THE UPPER MICHIGAN BORDER. ADDED PATCHY FOG TO THE WEATHER. ALSO SLOWED DOWN THE APPROACH OF CLOUDY CONDITIONS INVADING FROM THE NORTH TONIGHT. HIGH TEMPERATURE TUESDAY WAS WAY TOO WARM...EVEN 6 DEGREES ABOVE THE GFS ENSEMBLE HIGH GUIDANCE VALUES. MAY MAKE OTHER SMALLER ADJUSTMENTS THIS MORNING...BUT THOSE ARE THE MAIN POINTS FOR NOW. && .DISCUSSION (ISSUED AT 431 AM)... THE MAIN CONCERNS WITH THIS FORECAST PACKAGE ARE THE HIGH TEMPERATURES FOR TODAY AND THE CHANCE OF PRECIPITATION TONIGHT. WATER VAPOR IMAGERY AND RUC SHOWING A WEAK RIDGE OVER THE UPPER GREAT LAKES REGION...WEAK TROUGHS ARE OVER MARYLAND AND MISSOURI...AND ANOTHE RIDGE IS OVER THE ROCKIES CONTINENTAL DIVIDE. A DEEP CUTOFF LOW IS TRYING TO COME ASHORE OVER NORTHERN CALIFORNIA. SURFACE ANALYSIS DEPICTS LARGE HIGHS OVER THE OHIO RIVER VALLEY AND THE CENTRAL AND NORTHERN PLAINS. CLOSED LOWS ARE OVER SOUTHERN HUDSON BAY AND JUST OFF THE COAST OF NORTHERN CALIFORNIA. A COLD FRONT STRETCHES FROM THE HUDSON BAY LOW ACROSS NORTHERN ONTARIO AND NORTHERN MANITOBA. DRY AIR CONTINUES TO INVADE THE AREA FROM SOUTH CENTRAL CANADA. THE MODELS ARE IN VERY GOOD AGREEMENT THROUGH DAY 5 WITH ONLY MINOR DIFFERENCES IN STRENGTH. THE RIDGE OVER THE UPPER GREAT LAKES WILL SHIFT TO NEW ENGLAND TODAY AND WEAKENING SETTING UP A ZONAL FLOW ACROSS THE NORTHERN CONUS. WEAK SHORTWAVES CAUGHT IN THE ZONAL FLOW WILL SWEEP THROUGH THE FORECAST AREA AND UPPER MISSISSIPPI RIVER VALLEY TODAY. A RIDGE WILL START TO BUILD OVER THE NORTHERN ROCKIES. THE OHIO RIVER VALLEY SURFACE RIDGE WILL SPREAD OUT TODAY...WHILE A SURFACE LOW DEVELOPS OVER THE MIDDLE HIGH PLAINS. THE ANTI-CYCLONIC FLOW BEHIND THE OHIO RIVER VALLEY HIGH WILL CONTINUE TO DRAW WARMER AIR FROM THE PLAINS INTO THE UPPER GREAT LAKES TODAY. THE 850MB TEMPERATURE SHOULD BE ABOUT SAME AS YESTERDAY OVER THE AREA. TRAJECTORY PROGS AND GUIDANCE SUGGEST THAT TEMPERATURES WILL REACH WELL INTO THE UPPER 30S TO AROUND 40 TODAY ACROSS THE FORECAST AREA. THE COLD FRONT WILL EDGE SOUTHEAST INTO CENTRAL ONTARIO...JUST NORTH OF LAKE SUPERIOR. ISENTROPIC ASCENT AHEAD OF THE COLD FRONT COULD PRODUCE SOME SNOW SHOWERS JUST NORTH OF LAKE SUPERIOR AND ADD SOME CLOUDS FOR THE FORECAST AREA. THE MID LEVEL RIDGE WILL PUSH INTO THE WESTERN ALBERTA TONIGHT. A WEAK SHORTWAVE WILL EDGE INTO THE WESTERN U.P. FORECAST SOUNDINGS SUGGEST A STRONG INVERSION AROUND 900MB BY MIDNIGHT AND FAIRLY DRY ABOVE THIS POINT...AND MOIST BELOW. CONDITIONS STILL LOOK TOO DRY AND WARM FOR LES. THE COLD FRONT WILL SETTLE OVER NORTHERN LAKE SUPERIOR. VERY LITTLE ISENTROPIC ASCENT IS DEPICTED BY THE MODELS OVER THE AREA AS THE FRONT WILL BE VERY WEAK. THUS WILL KEEP THE FORECAST DRY. THE MID LEVEL LOW RIDGE WILL SHIFT INTO EASTERN ALBERTA ON MONDAY CAUSING A TROUGH TO DEVELOP OVER WESTERN ONTARIO. A WEAK SHORTWAVE WILL SLIDE THROUGH THE FORECAST AREA. A SURFACE LOW DEVELOPING OVER THE CENTRAL PLAINS WILL RELOCATE OVER THE MIDDLE MISSISSIPPI RIVER VALLEY. LOW LEVEL MOISTURE WILL INCREASE OVER THE AREA. HOWEVER...LOW LEVEL LIFT WILL CONTINUE TO BE WEAK. SO WILL ADD ONLY A SLIGHT CHANCE OF SNOW SHOWERS IN THE MORNING AND AREAS OF A CHANCE IN THE AFTERNOON. WILL USE NAM/GFS SOLUTION TO IDENTIFY AREAS. THE MID LEVEL TROUGH WILL SHIFT OVER THE FORECAST AREA MONDAY NIGHT ALONG WITH INCREASED SHORTWAVE ENERGY. THE SURFACE LOW WILL RACE ACROSS THE THE OHIO RIVER VALLEY REACH CENTRAL OHIO OVERNIGHT. AN 850MB THERMAL TROUGH WILL MOVE INTO THE FORECAST AREA INCREASING THE DELTA-T`S TO AROUND 20C. THIS WILL BE SUFFICIENT FOR LES TO DEVELOP THIS WILL CONTINUE THROUGH TUESDAY. A DEEPER TROUGH WILL SWEEP SLOWLY THROUGH THE UPPER GREAT LAKES ON TUESDAY AND TUESDAY NIGHT. MEANWHILE...THE SURFACE LOW WILL LIFT INTO NEW ENGLAND. A SURFACE RIDGE WILL EXPAND OVER THE NORTHERN AND CENTRAL PLAINS INTO THE UPPER MISSISSIPPI RIVER VALLEY. THIS WILL CONTINUE TO DRAW COLD ARCTIC AIR INTO THE REGION CAUSING THE LAKE-850MB DELTA-T`S TO INCREASE TO AROUND 23C...MORE THAN SUFFICIENT ENOUGH TO KEEP LES GOING OVER THE AREA ESPECIALLY IN FAVORED AREAS WITH A NORTH WIND. THE TROUGH WILL DEPART THE AREA ON WEDNESDAY AND WEDNESDAY NIGHT. THE THERMAL TROUGH WILL SHIFT INTO QUEBEC LATE. THE SURFACE RIDGE WILL SETTLE OVER THE FORECAST AREA AFFECTIVELY CAUSING THE LES TO END LATE. MEANWHILE...A LOW WILL BE DEVELOPING OVER THE NORTHERN PLAINS WITH AN ACCOMPANYING COLD FRONT DRAPED SOUTH INTO THE CENTRAL PLAINS. THE SURFACE LOW WILL SWING OUT OF THE NORTHERN PLAINS INTO NORTHERN WISCONSIN ON THUSDAY AND THURSDAY NIGHT. LOW LEVEL MOISTURE WILL SPREAD OVER THE AREA DUE TO THE SOUTHERN FLOW AHEAD OF THE LOW. ISENTROPIC ASCENT AHEAD OF THIS LOW AND SHORTWAVE ENERGY WILL HELP GENERATE SNOWS OVER THE AREA. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... VFR CEIGS AND VIS WILL START THE PERIOD...AS HIGH CLOUDS INVADE FROM THE NORTH. MVFR CEIGS AND VIS CAN THEN BE EXPECTED MAINLY AFTER 06Z TONIGHT AS A WEAK COLD FRONT ENTERS THE VICINITY. THIS FRONT WILL ALSO ACT TO SWING WESTERLY WINDS TO A MORE NORTHERLY DIRECTION...ASSISTING IN THE POTENTIAL FOR MVFR CLOUD COVER THROUGH THE REMAINDER OF THE PERIOD. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WEST SOUTHWEST WINDS OF 20 TO 30 KNOTS ARE EXPECTED THIS MORNING INTO EARLY AFTERNOON OVER CENTRAL LAKE SUPERIOR...ESPECIALLY ALONG THE WEST AND NORTH SIDE OF THE KEWEENAW PENSINSULA. NORTH WINDS TO 30 KNOTS ARE ALSO EXPECTED LATE MON NIGHT THROUGH TUE OVER CENTRAL AND EAST UPPER MI AS THE GRADIENT TIGHTENS BETWEEN LOW PRESSURE MOVING THROUGH THE OHIO VALLEY AND A HIGH BUILDING INTO THE PLAINS AND NORTHERN ONTARIO. THE NORTH WINDS WILL ALSO BRING IN COLDER AIR WITH FREEZING SPRAY DEVELOPING. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...KF DISCUSSION...DLG AVIATION...KF MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 855 AM EST SUN FEB 24 2008 .UPDATE... MADE SOME SIGNIFICANT CHANGES TO SKY GRIDS THROUGH DAY 2. IN THE NEAR TERM THIS WAS TO ACCOUNT FOR THE CLEAR SKY AND HAZE OVER MUCH OF THE AREA...AND FOG OVER NORTHERN WISCONSIN CREEPING SOUTHEASTWARD ACROSS THE UPPER MICHIGAN BORDER. ADDED PATCHY FOG TO THE WEATHER. ALSO SLOWED DOWN THE APPROACH OF CLOUDY CONDITIONS INVADING FROM THE NORTH TONIGHT. HIGH TEMPERATURE TUESDAY WAS WAY TOO WARM...EVEN 6 DEGREES ABOVE THE GFS ENSEMBLE HIGH GUIDANCE VALUES. MAY MAKE OTHER SMALLER ADJUSTMENTS THIS MORNING...BUT THOSE ARE THE MAIN POINTS FOR NOW. && .DISCUSSION (ISSUED AT 431 AM)... THE MAIN CONCERNS WITH THIS FORECAST PACKAGE ARE THE HIGH TEMPERATURES FOR TODAY AND THE CHANCE OF PRECIPITATION TONIGHT. WATER VAPOR IMAGERY AND RUC SHOWING A WEAK RIDGE OVER THE UPPER GREAT LAKES REGION...WEAK TROUGHS ARE OVER MARYLAND AND MISSOURI...AND ANOTHE RIDGE IS OVER THE ROCKIES CONTINENTAL DIVIDE. A DEEP CUTOFF LOW IS TRYING TO COME ASHORE OVER NORTHERN CALIFORNIA. SURFACE ANALYSIS DEPICTS LARGE HIGHS OVER THE OHIO RIVER VALLEY AND THE CENTRAL AND NORTHERN PLAINS. CLOSED LOWS ARE OVER SOUTHERN HUDSON BAY AND JUST OFF THE COAST OF NORTHERN CALIFORNIA. A COLD FRONT STRETCHES FROM THE HUDSON BAY LOW ACROSS NORTHERN ONTARIO AND NORTHERN MANITOBA. DRY AIR CONTINUES TO INVADE THE AREA FROM SOUTH CENTRAL CANADA. THE MODELS ARE IN VERY GOOD AGREEMENT THROUGH DAY 5 WITH ONLY MINOR DIFFERENCES IN STRENGTH. THE RIDGE OVER THE UPPER GREAT LAKES WILL SHIFT TO NEW ENGLAND TODAY AND WEAKENING SETTING UP A ZONAL FLOW ACROSS THE NORTHERN CONUS. WEAK SHORTWAVES CAUGHT IN THE ZONAL FLOW WILL SWEEP THROUGH THE FORECAST AREA AND UPPER MISSISSIPPI RIVER VALLEY TODAY. A RIDGE WILL START TO BUILD OVER THE NORTHERN ROCKIES. THE OHIO RIVER VALLEY SURFACE RIDGE WILL SPREAD OUT TODAY...WHILE A SURFACE LOW DEVELOPS OVER THE MIDDLE HIGH PLAINS. THE ANTI-CYCLONIC FLOW BEHIND THE OHIO RIVER VALLEY HIGH WILL CONTINUE TO DRAW WARMER AIR FROM THE PLAINS INTO THE UPPER GREAT LAKES TODAY. THE 850MB TEMPERATURE SHOULD BE ABOUT SAME AS YESTERDAY OVER THE AREA. TRAJECTORY PROGS AND GUIDANCE SUGGEST THAT TEMPERATURES WILL REACH WELL INTO THE UPPER 30S TO AROUND 40 TODAY ACROSS THE FORECAST AREA. THE COLD FRONT WILL EDGE SOUTHEAST INTO CENTRAL ONTARIO...JUST NORTH OF LAKE SUPERIOR. ISENTROPIC ASCENT AHEAD OF THE COLD FRONT COULD PRODUCE SOME SNOW SHOWERS JUST NORTH OF LAKE SUPERIOR AND ADD SOME CLOUDS FOR THE FORECAST AREA. THE MID LEVEL RIDGE WILL PUSH INTO THE WESTERN ALBERTA TONIGHT. A WEAK SHORTWAVE WILL EDGE INTO THE WESTERN U.P. FORECAST SOUNDINGS SUGGEST A STRONG INVERSION AROUND 900MB BY MIDNIGHT AND FAIRLY DRY ABOVE THIS POINT...AND MOIST BELOW. CONDITIONS STILL LOOK TOO DRY AND WARM FOR LES. THE COLD FRONT WILL SETTLE OVER NORTHERN LAKE SUPERIOR. VERY LITTLE ISENTROPIC ASCENT IS DEPICTED BY THE MODELS OVER THE AREA AS THE FRONT WILL BE VERY WEAK. THUS WILL KEEP THE FORECAST DRY. THE MID LEVEL LOW RIDGE WILL SHIFT INTO EASTERN ALBERTA ON MONDAY CAUSING A TROUGH TO DEVELOP OVER WESTERN ONTARIO. A WEAK SHORTWAVE WILL SLIDE THROUGH THE FORECAST AREA. A SURFACE LOW DEVELOPING OVER THE CENTRAL PLAINS WILL RELOCATE OVER THE MIDDLE MISSISSIPPI RIVER VALLEY. LOW LEVEL MOISTURE WILL INCREASE OVER THE AREA. HOWEVER...LOW LEVEL LIFT WILL CONTINUE TO BE WEAK. SO WILL ADD ONLY A SLIGHT CHANCE OF SNOW SHOWERS IN THE MORNING AND AREAS OF A CHANCE IN THE AFTERNOON. WILL USE NAM/GFS SOLUTION TO IDENTIFY AREAS. THE MID LEVEL TROUGH WILL SHIFT OVER THE FORECAST AREA MONDAY NIGHT ALONG WITH INCREASED SHORTWAVE ENERGY. THE SURFACE LOW WILL RACE ACROSS THE THE OHIO RIVER VALLEY REACH CENTRAL OHIO OVERNIGHT. AN 850MB THERMAL TROUGH WILL MOVE INTO THE FORECAST AREA INCREASING THE DELTA-T`S TO AROUND 20C. THIS WILL BE SUFFICIENT FOR LES TO DEVELOP THIS WILL CONTINUE THROUGH TUESDAY. A DEEPER TROUGH WILL SWEEP SLOWLY THROUGH THE UPPER GREAT LAKES ON TUESDAY AND TUESDAY NIGHT. MEANWHILE...THE SURFACE LOW WILL LIFT INTO NEW ENGLAND. A SURFACE RIDGE WILL EXPAND OVER THE NORTHERN AND CENTRAL PLAINS INTO THE UPPER MISSISSIPPI RIVER VALLEY. THIS WILL CONTINUE TO DRAW COLD ARCTIC AIR INTO THE REGION CAUSING THE LAKE-850MB DELTA-T`S TO INCREASE TO AROUND 23C...MORE THAN SUFFICIENT ENOUGH TO KEEP LES GOING OVER THE AREA ESPECIALLY IN FAVORED AREAS WITH A NORTH WIND. THE TROUGH WILL DEPART THE AREA ON WEDNESDAY AND WEDNESDAY NIGHT. THE THERMAL TROUGH WILL SHIFT INTO QUEBEC LATE. THE SURFACE RIDGE WILL SETTLE OVER THE FORECAST AREA AFFECTIVELY CAUSING THE LES TO END LATE. MEANWHILE...A LOW WILL BE DEVELOPING OVER THE NORTHERN PLAINS WITH AN ACCOMPANYING COLD FRONT DRAPED SOUTH INTO THE CENTRAL PLAINS. THE SURFACE LOW WILL SWING OUT OF THE NORTHERN PLAINS INTO NORTHERN WISCONSIN ON THUSDAY AND THURSDAY NIGHT. LOW LEVEL MOISTURE WILL SPREAD OVER THE AREA DUE TO THE SOUTHERN FLOW AHEAD OF THE LOW. ISENTROPIC ASCENT AHEAD OF THIS LOW AND SHORTWAVE ENERGY WILL HELP GENERATE SNOWS OVER THE AREA. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT DRY AIR MASS TO BRING VFR CONDITIONS THRU THE FCST PD AT BOTH TAF SITES WITH MODERATELY STRONG WLY FLOW TO THE N OF HI PRES IN THE OH VALLEY. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WEST SOUTHWEST WINDS OF 20 TO 30 KNOTS ARE EXPECTED THIS MORNING INTO EARLY AFTERNOON OVER CENTRAL LAKE SUPERIOR...ESPECIALLY ALONG THE WEST AND NORTH SIDE OF THE KEWEENAW PENSINSULA. NORTH WINDS TO 30 KNOTS ARE ALSO EXPECTED LATE MON NIGHT THROUGH TUE OVER CENTRAL AND EAST UPPER MI AS THE GRADIENT TIGHTENS BETWEEN LOW PRESSURE MOVING THROUGH THE OHIO VALLEY AND A HIGH BUILDING INTO THE PLAINS AND NORTHERN ONTARIO. THE NORTH WINDS WILL ALSO BRING IN COLDER AIR WITH FREEZING SPRAY DEVELOPING. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...KF DISCUSSION...DLG AVIATION...KC MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 431 AM EST SUN FEB 24 2008 .DISCUSSION... THE MAIN CONCERNS WITH THIS FORECAST PACKAGE ARE THE HIGH TEMPERATURES FOR TODAY AND THE CHANCE OF PRECIPITATION TONIGHT. WATER VAPOR IMAGERY AND RUC SHOWING A WEAK RIDGE OVER THE UPPER GREAT LAKES REGION...WEAK TROUGHS ARE OVER MARYLAND AND MISSOURI...AND ANOTHE RIDGE IS OVER THE ROCKIES CONTINENTAL DIVIDE. A DEEP CUTOFF LOW IS TRYING TO COME ASHORE OVER NORTHERN CALIFORNIA. SURFACE ANALYSIS DEPICTS LARGE HIGHS OVER THE OHIO RIVER VALLEY AND THE CENTRAL AND NORTHERN PLAINS. CLOSED LOWS ARE OVER SOUTHERN HUDSON BAY AND JUST OFF THE COAST OF NORTHERN CALIFORNIA. A COLD FRONT STRETCHES FROM THE HUDSON BAY LOW ACROSS NORTHERN ONTARIO AND NORTHERN MANITOBA. DRY AIR CONTINUES TO INVADE THE AREA FROM SOUTH CENTRAL CANADA. THE MODELS ARE IN VERY GOOD AGREEMENT THROUGH DAY 5 WITH ONLY MINOR DIFFERENCES IN STRENGTH. THE RIDGE OVER THE UPPER GREAT LAKES WILL SHIFT TO NEW ENGLAND TODAY AND WEAKENING SETTING UP A ZONAL FLOW ACROSS THE NORTHERN CONUS. WEAK SHORTWAVES CAUGHT IN THE ZONAL FLOW WILL SWEEP THROUGH THE FORECAST AREA AND UPPER MISSISSIPPI RIVER VALLEY TODAY. A RIDGE WILL START TO BUILD OVER THE NORTHERN ROCKIES. THE OHIO RIVER VALLEY SURFACE RIDGE WILL SPREAD OUT TODAY...WHILE A SURFACE LOW DEVELOPS OVER THE MIDDLE HIGH PLAINS. THE ANTI-CYCLONIC FLOW BEHIND THE OHIO RIVER VALLEY HIGH WILL CONTINUE TO DRAW WARMER AIR FROM THE PLAINS INTO THE UPPER GREAT LAKES TODAY. THE 850MB TEMPERATURE SHOULD BE ABOUT SAME AS YESTERDAY OVER THE AREA. TRAJECTORY PROGS AND GUIDANCE SUGGEST THAT TEMPERATURES WILL REACH WELL INTO THE UPPER 30S TO AROUND 40 TODAY ACROSS THE FORECAST AREA. THE COLD FRONT WILL EDGE SOUTHEAST INTO CENTRAL ONTARIO...JUST NORTH OF LAKE SUPERIOR. ISENTROPIC ASCENT AHEAD OF THE COLD FRONT COULD PRODUCE SOME SNOW SHOWERS JUST NORTH OF LAKE SUPERIOR AND ADD SOME CLOUDS FOR THE FORECAST AREA. THE MID LEVEL RIDGE WILL PUSH INTO THE WESTERN ALBERTA TONIGHT. A WEAK SHORTWAVE WILL EDGE INTO THE WESTERN U.P. FORECAST SOUNDINGS SUGGEST A STRONG INVERSION AROUND 900MB BY MIDNIGHT AND FAIRLY DRY ABOVE THIS POINT...AND MOIST BELOW. CONDITIONS STILL LOOK TOO DRY AND WARM FOR LES. THE COLD FRONT WILL SETTLE OVER NORTHERN LAKE SUPERIOR. VERY LITTLE ISENTROPIC ASCENT IS DEPICTED BY THE MODELS OVER THE AREA AS THE FRONT WILL BE VERY WEAK. THUS WILL KEEP THE FORECAST DRY. THE MID LEVEL LOW RIDGE WILL SHIFT INTO EASTERN ALBERTA ON MONDAY CAUSING A TROUGH TO DEVELOP OVER WESTERN ONTARIO. A WEAK SHORTWAVE WILL SLIDE THROUGH THE FORECAST AREA. A SURFACE LOW DEVELOPING OVER THE CENTRAL PLAINS WILL RELOCATE OVER THE MIDDLE MISSISSIPPI RIVER VALLEY. LOW LEVEL MOISTURE WILL INCREASE OVER THE AREA. HOWEVER...LOW LEVEL LIFT WILL CONTINUE TO BE WEAK. SO WILL ADD ONLY A SLIGHT CHANCE OF SNOW SHOWERS IN THE MORNING AND AREAS OF A CHANCE IN THE AFTERNOON. WILL USE NAM/GFS SOLUTION TO IDENTIFY AREAS. THE MID LEVEL TROUGH WILL SHIFT OVER THE FORECAST AREA MONDAY NIGHT ALONG WITH INCREASED SHORTWAVE ENERGY. THE SURFACE LOW WILL RACE ACROSS THE THE OHIO RIVER VALLEY REACH CENTRAL OHIO OVERNIGHT. AN 850MB THERMAL TROUGH WILL MOVE INTO THE FORECAST AREA INCREASING THE DELTA-T`S TO AROUND 20C. THIS WILL BE SUFFICIENT FOR LES TO DEVELOP THIS WILL CONTINUE THROUGH TUESDAY. A DEEPER TROUGH WILL SWEEP SLOWLY THROUGH THE UPPER GREAT LAKES ON TUESDAY AND TUESDAY NIGHT. MEANWHILE...THE SURFACE LOW WILL LIFT INTO NEW ENGLAND. A SURFACE RIDGE WILL EXPAND OVER THE NORTHERN AND CENTRAL PLAINS INTO THE UPPER MISSISSIPPI RIVER VALLEY. THIS WILL CONTINUE TO DRAW COLD ARCTIC AIR INTO THE REGION CAUSING THE LAKE-850MB DELTA-T`S TO INCREASE TO AROUND 23C...MORE THAN SUFFICIENT ENOUGH TO KEEP LES GOING OVER THE AREA ESPECIALLY IN FAVORED AREAS WITH A NORTH WIND. THE TROUGH WILL DEPART THE AREA ON WEDNESDAY AND WEDNESDAY NIGHT. THE THERMAL TROUGH WILL SHIFT INTO QUEBEC LATE. THE SURFACE RIDGE WILL SETTLE OVER THE FORECAST AREA AFFECTIVELY CAUSING THE LES TO END LATE. MEANWHILE...A LOW WILL BE DEVELOPING OVER THE NORTHERN PLAINS WITH AN ACCOMPANYING COLD FRONT DRAPED SOUTH INTO THE CENTRAL PLAINS. THE SURFACE LOW WILL SWING OUT OF THE NORTHERN PLAINS INTO NORTHERN WISCONSIN ON THUSDAY AND THURSDAY NIGHT. LOW LEVEL MOISTURE WILL SPREAD OVER THE AREA DUE TO THE SOUTHERN FLOW AHEAD OF THE LOW. ISENTROPIC ASCENT AHEAD OF THIS LOW AND SHORTWAVE ENERGY WILL HELP GENERATE SNOWS OVER THE AREA. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT DRY AIR MASS TO BRING VFR CONDITIONS THRU THE FCST PD AT BOTH TAF SITES WITH MODERATELY STRONG WLY FLOW TO THE N OF HI PRES IN THE OH VALLEY. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WEST SOUTHWEST WINDS OF 20 TO 30 KNOTS ARE EXPECTED THIS MORNING INTO EARLY AFTERNOON OVER CENTRAL LAKE SUPERIOR...ESPECIALLY ALONG THE WEST AND NORTH SIDE OF THE KEWEENAW PENSINSULA. NORTH WINDS TO 30 KNOTS ARE ALSO EXPECTED LATE MON NIGHT THROUGH TUE OVER CENTRAL AND EAST UPPER MI AS THE GRADIENT TIGHTENS BETWEEN LOW PRESSURE MOVING THROUGH THE OHIO VALLEY AND A HIGH BUILDING INTO THE PLAINS AND NORTHERN ONTARIO. THE NORTH WINDS WILL ALSO BRING IN COLDER AIR WITH FREEZING SPRAY DEVELOPING. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...DLG AVIATION...KC MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1015 AM CST MON FEB 25 2008 .UPDATE... UPDATED THE FORECAST TO REMOVE THE DENSE FOG ADVISORY...AND TRIM DOWN SNOW AMOUNTS IN THE FAR SOUTH FOR TODAY. WEAK FRONTAL BOUNDARY OVER THE UPPER MIDWEST WILL CONTINUE TO SLIDE SOUTHEAST OVER WISCONSIN INTO SOUTHEAST MN TODAY. SFC LOW OVR EAST CENTRAL KANSAS...WILL TRACK EAST-SOUTHEAST OVR CNTRL MO DURING THE PERIOD. PRECIP OCCURRING OVR FAR SOUTH HAS BEEN A MIXTURE OF LIGHT SNOW OR FREEZING RAIN IN THE FAR SOUTH. HAVE TRIMMED POPS AND SNOWFALL AMOUNTS FOR TODAY OVER THE EXTREME SOUTH. && .DISCUSSION.../ISSUED 256 AM CST MON FEB 25 2008/ A WEAK SHORTWAVE TROUGH IS FEATURED OVER NORTHWESTERN NEBRASKA THIS MORNING ON WATER VAPOR IMAGERY. ASSOCIATED RETURNS ON RADAR CORRELATE WITH ISENTROPIC UPGLIDE ON THE RUC 290K SURFACE. THIS AREA IS FORECAST TO SLIDE ACROSS SOUTHERN MN AND NORTHERN IA TODAY...WHICH CONCURS WITH THE NAM/GFS/SREF PROGGED 700MB LOW TRACK FROM SWRN SD ACROSS ERN NE AND SRN IA. MEASURABLE SNOWFALL POTENTIAL IS THEREFORE RESTRICTED TO EXTREME SOUTHERN MN...WITH MAX AMOUNTS IN THE CWA OF 1 TO 2 INCHES ALONG/SOUTH OF THE INTERSTATE 90 CORRIDOR. TRACE SNOWFALL AMOUNTS ARE EXPECTED ELSEWHERE. SNOWFALL ACCUMULATIONS WILL ALSO BE INHIBITED BY THE FACT THAT A PERIOD OF FREEZING RAIN WILL BE POSSIBLE ACROSS PORTIONS OF SOUTHWEST AND SOUTH CENTRAL MN THIS MORNING...WHERE 08Z TEMPERATURES WERE IN THE MID/UPPER 20S. NAM/GFS/RUC BUFKIT SOUNDINGS FOR REDWOOD FALLS ARE INDICATIVE OF THE FREEZING PRECIP POTENTIAL...WITH A TRANSITION TO SNOW COMMON BETWEEN 10 AND NOON. QPF DURING THIS TIMEFRAME IS LIGHT HOWEVER...SO MINIMAL ICE ACCUMULATIONS ARE ANTICIPATED. THE OTHER CONCERN THIS MORNING IS THE DENSE FOG THAT IS PLAGUING THE MIDSECTION OF THE FORECAST AREA...WHERE WIDESPREAD METARS ARE REPORTING SUB-QUARTER MILE VISIBILITIES. WILL LIKELY EXPAND THE ADVISORY INTO PORTIONS OF WEST CENTRAL WISCONSIN THIS MORNING...WHERE VISIBILITIES WILL LIKELY CONTINUE TO DECLINE IN THE TROUGH AXIS. CONVERSELY...WILL BE ABLE TO DROP A FEW COUNTIES OVER WEST CENTRAL MN...WHERE IMPROVEMENT IN VISIBILITIES IS OCCURRING DUE TO THE SHIFT TO NORTHWESTERLY WINDS AND INCREASE IN MID LEVEL CLOUD COVER. THE EXTENSIVE CLOUD COVER WILL MINIMIZE DIURNAL WARMING TODAY...ALTHOUGH ELEVATED OVERNIGHT MINIMUMS WILL CONTRIBUTE TO NEAR-NORMAL HIGHS BETWEEN 28 AND 34 DEGREES. A WEAK SECONDARY WAVE WILL PLUMMET ACROSS MN/WI ON TUESDAY...WHICH MAY GENERATE SOME FLURRIES. HIGHS WILL GENERALLY RANGE BETWEEN 10 AND 15 DEGREES BELOW NORMAL ON TUESDAY AND WEDNESDAY...WITH READINGS MAINLY BETWEEN 20 AND 25 DEGREES. A MORE NOTABLE SHORTWAVE AND SURFACE TROUGH WILL DIVE SOUTH FROM CANADA ON THURSDAY. 800MB-700MB FRONTOGENESIS SPREADS ACROSS THE CWA ON THURSDAY. GFS COBB OUTPUT GENERALLY INDICATES SNOWFALL ACCUMULATIONS BETWEEN ONE AND THREE INCHES FOR THE THURSDAY EVENT...WHICH SEEM REASONABLE. && .AVIATION.../18Z TAF ISSUANCE/ WEATHER CONDITIONS WILL SLOWLY IMPROVE OVER THE TAF SITES DURING THE PERIOD. STRATUS AND FOG WILL PERSIST AHEAD OF THE WEAK TROUGH AXIS OVR NORTHWEST WISCONSIN INTO SOUTH CENTRAL MN THROUGH EARLY AFTERNOON. LIFR TO IFR CONDITIONS WILL PREVAIL WITH VSBL SLOWLY LIFTING TO MVFR THIS AFTERNOON IN THE WAKE OF THE TROUGH AXIS. CEILINGS LIFTING TO MVFR TO VFR CONDITIONS TONIGHT. DRY LOW LEVEL AIRFLOW ALOFT WILL CONTINUE TO FILTER ACROSS THE UPPER MIDWEST DURG THE PERIOD. SFC LOW RESPONSIBLE FOR THE WINTRY PRECIP...CONTINUE TO DRIFT FURTHER SOUTH THAN PREVIOUS THINKING. SOME LIGHT SNOW DEVELOPING OVR THE TAF SITES...ESPECIALLY SOUTH OF INTERSTATE 90 CORRIDOR. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR BLUE EARTH-FARIBAULT-MARTIN-WATONWAN. WI...NONE. && $$ LS/BAP/JVM mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 632 AM CST MON FEB 25 2008 .UPDATE... ISSUED A WINTER WEATHER ADVISORY FOR PORTIONS OF SOUTH CENTRAL MINNESOTA. EARLY MORNING SURFACE OBS AND REPORTS ACROSS SOUTHWEST MN INDICATE THAT FREEZING RAIN IS THE INITIAL PRECIP TYPE AT ONSET. WITH SUB-FREEZING SURFACE OBS AND A SIMILAR LOW LEVEL PROFILE ACROSS SOUTH CENTRAL MN...EXPECT SOME LIGHT ICE ACCUMULATIONS ARE POSSIBLE THIS MORNING. SINCE FREEZING RAIN WILL BE FOLLOWED BY A PERIOD OF SNOW /1 TO 3 INCHES/...ELECTED TO GO WITH A WINTER WEATHER ADVISORY. ALSO TRIMMED THE WESTERN EDGE OF THE DENSE FOG ADVISORY...AS SURFACE VISIBILITIES HAVE INCREASED TO BETWEEN ONE AND THREE MILES. && .DISCUSSION.../ISSUED 256 AM CST MON FEB 25 2008/ A WEAK SHORTWAVE TROUGH IS FEATURED OVER NORTHWESTERN NEBRASKA THIS MORNING ON WATER VAPOR IMAGERY. ASSOCIATED RETURNS ON RADAR CORRELATE WITH ISENTROPIC UPGLIDE ON THE RUC 290K SURFACE. THIS AREA IS FORECAST TO SLIDE ACROSS SOUTHERN MN AND NORTHERN IA TODAY...WHICH CONCURS WITH THE NAM/GFS/SREF PROGGED 700MB LOW TRACK FROM SWRN SD ACROSS ERN NE AND SRN IA. MEASURABLE SNOWFALL POTENTIAL IS THEREFORE RESTRICTED TO EXTREME SOUTHERN MN...WITH MAX AMOUNTS IN THE CWA OF 1 TO 2 INCHES ALONG/SOUTH OF THE INTERSTATE 90 CORRIDOR. TRACE SNOWFALL AMOUNTS ARE EXPECTED ELSEWHERE. SNOWFALL ACCUMULATIONS WILL ALSO BE INHIBITED BY THE FACT THAT A PERIOD OF FREEZING RAIN WILL BE POSSIBLE ACROSS PORTIONS OF SOUTHWEST AND SOUTH CENTRAL MN THIS MORNING...WHERE 08Z TEMPERATURES WERE IN THE MID/UPPER 20S. NAM/GFS/RUC BUFKIT SOUNDINGS FOR REDWOOD FALLS ARE INDICATIVE OF THE FREEZING PRECIP POTENTIAL...WITH A TRANSITION TO SNOW COMMON BETWEEN 10 AND NOON. QPF DURING THIS TIMEFRAME IS LIGHT HOWEVER...SO MINIMAL ICE ACCUMULATIONS ARE ANTICIPATED. THE OTHER CONCERN THIS MORNING IS THE DENSE FOG THAT IS PLAGUING THE MIDSECTION OF THE FORECAST AREA...WHERE WIDESPREAD METARS ARE REPORTING SUB-QUARTER MILE VISIBILITIES. WILL LIKELY EXPAND THE ADVISORY INTO PORTIONS OF WEST CENTRAL WISCONSIN THIS MORNING...WHERE VISIBILITIES WILL LIKELY CONTINUE TO DECLINE IN THE TROUGH AXIS. CONVERSELY...WILL BE ABLE TO DROP A FEW COUNTIES OVER WEST CENTRAL MN...WHERE IMPROVEMENT IN VISIBILITIES IS OCCURRING DUE TO THE SHIFT TO NORTHWESTERLY WINDS AND INCREASE IN MID LEVEL CLOUD COVER. THE EXTENSIVE CLOUD COVER WILL MINIMIZE DIURNAL WARMING TODAY...ALTHOUGH ELEVATED OVERNIGHT MINIMUMS WILL CONTRIBUTE TO NEAR-NORMAL HIGHS BETWEEN 28 AND 34 DEGREES. A WEAK SECONDARY WAVE WILL PLUMMET ACROSS MN/WI ON TUESDAY...WHICH MAY GENERATE SOME FLURRIES. HIGHS WILL GENERALLY RANGE BETWEEN 10 AND 15 DEGREES BELOW NORMAL ON TUESDAY AND WEDNESDAY...WITH READINGS MAINLY BETWEEN 20 AND 25 DEGREES. A MORE NOTABLE SHORTWAVE AND SURFACE TROUGH WILL DIVE SOUTH FROM CANADA ON THURSDAY. 800MB-700MB FRONTOGENESIS SPREADS ACROSS THE CWA ON THURSDAY. GFS COBB OUTPUT GENERALLY INDICATES SNOWFALL ACCUMULATIONS BETWEEN ONE AND THREE INCHES FOR THE THURSDAY EVENT...WHICH SEEM REASONABLE. && .AVIATION.../12Z TAF ISSUANCE/ MAIN CONCERN NEXT SVRL HRS IS WDSPRD DNS FOG EC AND SE MN. PASSAGE OF WK CDFNT WHICH AT 10Z RAN FROM NR CBG TO HCD TO MML WL IMPV VSBY AS DRIER AIR INFILTRATES IN. VSBYS WL LIKELY RMN AOB 1/4SM AT MSP TIL 14Z TO 15Z AND RWF BY TAF ISSUE TIME. OTHER CONCERN IS A SML CHC OF -FZRA SW MN NEXT FEW HRS...MADE A MENTION AT RWF TAF FOR A COUPLE HRS...BUT MAIN THREAT WL BE S OF RWF. AS WK CDFNT MVS THRU TEMPS IN LWR FEW THOUSAND FEET WL COOL ENUF FOR ANY PCPN TO CHG TO -SN. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR ANOKA-BLUE EARTH-CARVER-CHISAGO-DAKOTA-FARIBAULT-FREEBORN-GOODHUE- HENNEPIN-ISANTI-KANABEC-LE SUEUR-MCLEOD-NICOLLET-RAMSEY- RICE-SCOTT-SHERBURNE-SIBLEY-STEELE-WASECA-WASHINGTON-WRIGHT. WINTER WEATHER ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR BLUE EARTH-FARIBAULT-MARTIN-WATONWAN. WI...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR BARRON-POLK. && $$ LS/BAP mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 628 AM CST MON FEB 25 2008 .UPDATE... DROPPING DFA OVER SWRN CWA. VISIBILTY CONTINUES TO IMPROVE AS LAYER OF CAA BEGINS TO DEEPEN. TWEKED POPS AS WELL OVER CWA AS VERY LITTLE PRECIP OCCURING WITH SYSTEM DROPPING SE FROM MANITOBA. && .PREV DISCUSSION... /ISSUED 334 AM CST MON FEB 25 2008/ DISCUSSION... FAIRLY QUIET WEATHER PATTERN REMAINS ACROSS CWA. TWO NOTEWORTHY ITEMS WILL BE POTENTIAL FOR LAKE EFFECT SNOW IN SHORT TERM... AND CHANCE OF SYNOPTIC SCALE SNOW THURSDAY/FRIDAY. TODAY...MSAS ANALYSIS REVEALS WEAK SFC LOW OVER WRN SUPERIOR LOSING IDENTITY...PHASING INTO A SFC TROUGH ACROSS NORTHERN EDGE OF CWA. LATEST RUC13 INDICATES TRANSIENT AREA OF WARM ADVECTION NEAR 85H IS WORKING EAST ALONG SRN EDGE OF CWA EARLY THIS MORNING. DENSE FOG IS OCCURRING BENEATH THIS ENHANCED INVERSION. SUSPECT THAT WRN EDGE OF DFA WILL ERODE QUICKLY AS COOLING OCCURS BEHIND 925/85H SHIFT TO NW WIND WITHIN THE NEXT FEW HRS...MAY NEED TO DROP DFA EARLIER OVER SW CWA. OTHERWISE..NW MID LVL FLOW WILL KEEP FAIR AMOUNT OF CLOUD COVER ACROSS REGION EARLY BEFORE SOME BREAKS DEVELOP BY AFTERNOON OVER SWRN CWA IN AREA OF DEEPER LAYER DRYING PER EC/GFS. TONIGHT/TUESDAY...MAIN FOCUS IS ON DEVELOPING LES. FAVORED PARAMETERS INCLUDE SFC/85H MINIMAL SHEAR...SUFFICIENT SYNOPTIC SCALE RH...FCST OMEGA WITHIN FAVORED DENDRITE ZONE AND PROLONGED PERIOD OF LES POTENTIAL. NEGATIVE FACTORS INCLUDE MORE ICE COVER ON LAKE ALONG FCST TRAJECTORY AND INVERSION HEIGHT OF 3/4K. WILL LET NEXT SHIFT DECIDE IF ENOUGH CONFIDENCE PREVAILS TO ISSUE LES ADVISORY. SUSPECT THAT WE WILL HAVE A EXTENDED PERIOD OF LIGHT SNOW...PERHAPS INCREASING TUESDAY EVENING WITH ADDITION OF ENHANCED LIFT PROVIDED BY DIGGING SHORTWAVE. EXTENDED...WEDNESDAY THROUGH SATURDAY...MID LVL HEIGHTS INCREASE OVER REGION SOMEWHAT HOWEVER NWRLY FLOW PREVAILS. WITH MEAN RIDGE ALONG WRN PART OF CONUS..ANY SHORTWAVE TRAVERSING PACNW WILL AMPLIFY AS IT HEADS FROM WRN CANADA INTO UPPER MIDWEST. FAIRLY DECENT MDL CONSENSUS WITH EC/GFS/CMC PUSHING SNOW ACROSS MOST OF CWA THURSDAY INTO FRIDAY. AVIATION... AREAS OF DENSE FOG AND IFR/LIFR CEILINGS CAN BE EXPECTED THIS MORNING...MAINLY ALONG AND SOUTH AND EAST OF A LINE FROM KBRD TO KHIB TO KBFW...INCLUDING NORTHWEST WISCONSIN. THERE WERE HIGH CLOUDS PASSING OVERHEAD...LEADING TO VARIABILITY IN BOTH VSBYS AND CEILINGS THIS MORNING. THE FOG AND LOW DECK SHOULD RISE THROUGH THE DAY TODAY...AS WINDS TURN NORTHERLY. AN MVFR DECK OF CLOUDS OVER NORTHWEST MINNESOTA AND NORTHERN ONTARIO WILL SLOWLY SINK SOUTH TODAY. AREAS ALONG THE SOUTH SHORE OF LAKE SUPERIOR WILL SEE SNOW SHOWERS DEVELOP LATER TONIGHT...LEADING TO IFR CONDITIONS IN SPOTS. && POINT TEMPS/POPS... DLH 29 12 20 4 / 20 20 10 10 INL 25 5 17 2 / 10 10 10 10 BRD 33 13 23 7 / 20 10 10 10 HYR 33 13 22 3 / 30 30 20 10 ASX 31 15 20 5 / 30 30 30 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 8 AM CST THIS MORNING FOR PINE. WI...DENSE FOG ADVISORY UNTIL 8 AM CST THIS MORNING FOR BURNETT- WASHBURN. $$ CANNON/MELDE mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 451 AM CST MON FEB 25 2008 .DISCUSSION...ISSUED AT 256 AM CST A WEAK SHORTWAVE TROUGH IS FEATURED OVER NORTHWESTERN NEBRASKA THIS MORNING ON WATER VAPOR IMAGERY. ASSOCIATED RETURNS ON RADAR CORRELATE WITH ISENTROPIC UPGLIDE ON THE RUC 290K SURFACE. THIS AREA IS FORECAST TO SLIDE ACROSS SOUTHERN MN AND NORTHERN IA TODAY...WHICH CONCURS WITH THE NAM/GFS/SREF PROGGED 700MB LOW TRACK FROM SWRN SD ACROSS ERN NE AND SRN IA. MEASURABLE SNOWFALL POTENTIAL IS THEREFORE RESTRICTED TO EXTREME SOUTHERN MN...WITH MAX AMOUNTS IN THE CWA OF 1 TO 2 INCHES ALONG/SOUTH OF THE INTERSTATE 90 CORRIDOR. TRACE SNOWFALL AMOUNTS ARE EXPECTED ELSEWHERE. SNOWFALL ACCUMULATIONS WILL ALSO BE INHIBITED BY THE FACT THAT A PERIOD OF FREEZING RAIN WILL BE POSSIBLE ACROSS PORTIONS OF SOUTHWEST AND SOUTH CENTRAL MN THIS MORNING...WHERE 08Z TEMPERATURES WERE IN THE MID/UPPER 20S. NAM/GFS/RUC BUFKIT SOUNDINGS FOR REDWOOD FALLS ARE INDICATIVE OF THE FREEZING PRECIP POTENTIAL...WITH A TRANSITION TO SNOW COMMON BETWEEN 10 AND NOON. QPF DURING THIS TIMEFRAME IS LIGHT HOWEVER...SO MINIMAL ICE ACCUMULATIONS ARE ANTICIPATED. THE OTHER CONCERN THIS MORNING IS THE DENSE FOG THAT IS PLAGUING THE MIDSECTION OF THE FORECAST AREA...WHERE WIDESPREAD METARS ARE REPORTING SUB-QUARTER MILE VISIBILITIES. WILL LIKELY EXPAND THE ADVISORY INTO PORTIONS OF WEST CENTRAL WISCONSIN THIS MORNING...WHERE VISIBILITIES WILL LIKELY CONTINUE TO DECLINE IN THE TROUGH AXIS. CONVERSELY...WILL BE ABLE TO DROP A FEW COUNTIES OVER WEST CENTRAL MN...WHERE IMPROVEMENT IN VISIBILITIES IS OCCURRING DUE TO THE SHIFT TO NORTHWESTERLY WINDS AND INCREASE IN MID LEVEL CLOUD COVER. THE EXTENSIVE CLOUD COVER WILL MINIMIZE DIURNAL WARMING TODAY...ALTHOUGH ELEVATED OVERNIGHT MINIMUMS WILL CONTRIBUTE TO NEAR-NORMAL HIGHS BETWEEN 28 AND 34 DEGREES. A WEAK SECONDARY WAVE WILL PLUMMET ACROSS MN/WI ON TUESDAY...WHICH MAY GENERATE SOME FLURRIES. HIGHS WILL GENERALLY RANGE BETWEEN 10 AND 15 DEGREES BELOW NORMAL ON TUESDAY AND WEDNESDAY...WITH READINGS MAINLY BETWEEN 20 AND 25 DEGREES. A MORE NOTABLE SHORTWAVE AND SURFACE TROUGH WILL DIVE SOUTH FROM CANADA ON THURSDAY. 800MB-700MB FRONTOGENESIS SPREADS ACROSS THE CWA ON THURSDAY. GFS COBB OUTPUT GENERALLY INDICATES SNOWFALL ACCUMULATIONS BETWEEN ONE AND THREE INCHES FOR THE THURSDAY EVENT...WHICH SEEM REASONABLE. && .AVIATION.../12Z TAF ISSUANCE/ MAIN CONCERN NEXT SVRL HRS IS WDSPRD DNS FOG EC AND SE MN. PASSAGE OF WK CDFNT WHICH AT 10Z RAN FROM NR CBG TO HCD TO MML WL IMPV VSBY AS DRIER AIR INFLITRATES IN. VSBYS WL LIKELY RMN AOB 1/4SM AT MSP TIL 14Z TO 15Z AND RWF BY TAF ISSUE TIME. OTHER CONCERN IS A SML CHC OF -FZRA SW MN NEXT FEW HRS...MADE A MENTION AT RWF TAF FOR A COUPLE HRS...BUT MAIN THREAT WL BE S OF RWF. AS WK CDFNT MVS THRU TEMPS IN LWR FEW THOUSAND FEET WL COOL ENUF FOR ANY PCPN TO CHG TO -SN. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR ANOKA-BENTON- BLUE EARTH-BROWN-CARVER-CHISAGO-DAKOTA-FARIBAULT-FREEBORN- GOODHUE-HENNEPIN-ISANTI-KANABEC-LE SUEUR-MARTIN-MCLEOD- MILLE LACS-MORRISON-NICOLLET-RAMSEY-RICE-SCOTT-SHERBURNE- SIBLEY-STEELE-WASECA-WASHINGTON-WATONWAN-WRIGHT. WI...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR BARRON-POLK. && $$ BAP/LS mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 334 AM CST MON FEB 25 2008 .DISCUSSION... FAIRLY QUIET WEATHER PATTERN REMAINS ACROSS CWA. TWO NOTEWORTHY ITEMS WILL BE POTENTIAL FOR LAKE EFFECT SNOW IN SHORT TERM... AND CHANCE OF SYNOPTIC SCALE SNOW THURSDAY/FRIDAY. TODAY...MSAS ANALYSIS REVEALS WEAK SFC LOW OVER WRN SUPERIOR LOSING IDENTITY...PHASING INTO A SFC TROUGH ACROSS NORTHERN EDGE OF CWA. LATEST RUC13 INDICATES TRANSIENT AREA OF WARM ADVECTION NEAR 85H IS WORKING EAST ALONG SRN EDGE OF CWA EARLY THIS MORNING. DENSE FOG IS OCCURRING BENEATH THIS ENHANCED INVERSION. SUSPECT THAT WRN EDGE OF DFA WILL ERODE QUICKLY AS COOLING OCCURS BEHIND 925/85H SHIFT TO NW WIND WITHIN THE NEXT FEW HRS...MAY NEED TO DROP DFA EARLIER OVER SW CWA. OTHERWISE..NW MID LVL FLOW WILL KEEP FAIR AMOUNT OF CLOUD COVER ACROSS REGION EARLY BEFORE SOME BREAKS DEVELOP BY AFTERNOON OVER SWRN CWA IN AREA OF DEEPER LAYER DRYING PER EC/GFS. TONIGHT/TUESDAY...MAIN FOCUS IS ON DEVELOPING LES. FAVORED PARAMETERS INCLUDE SFC/85H MINIMAL SHEAR...SUFFICIENT SYNOPTIC SCALE RH...FCST OMEGA WITHIN FAVORED DENDRITE ZONE AND PROLONGED PERIOD OF LES POTENTIAL. NEGATIVE FACTORS INCLUDE MORE ICE COVER ON LAKE ALONG FCST TRAJECTORY AND INVERSION HEIGHT OF 3/4K. WILL LET NEXT SHIFT DECIDE IF ENOUGH CONFIDENCE PREVAILS TO ISSUE LES ADVISORY. SUSPECT THAT WE WILL HAVE A EXTENDED PERIOD OF LIGHT SNOW...PERHAPS INCREASING TUESDAY EVENING WITH ADDITION OF ENHANCED LIFT PROVIDED BY DIGGING SHORTWAVE. EXTENDED...WEDNESDAY THROUGH SATURDAY...MID LVL HEIGHTS INCREASE OVER REGION SOMEWHAT HOWEVER NWRLY FLOW PREVAILS. WITH MEAN RIDGE ALONG WRN PART OF CONUS..ANY SHORTWAVE TRAVERSING PACNW WILL AMPLIFY AS IT HEADS FROM WRN CANADA INTO UPPER MIDWEST. FAIRLY DECENT MDL CONSENSUS WITH EC/GFS/CMC PUSHING SNOW ACROSS MOST OF CWA THURSDAY INTO FRIDAY. && .AVIATION... AREAS OF DENSE FOG AND IFR/LIFR CEILINGS CAN BE EXPECTED THIS MORNING...MAINLY ALONG AND SOUTH AND EAST OF A LINE FROM KBRD TO KHIB TO KBFW...INCLUDING NORTHWEST WISCONSIN. THERE WERE HIGH CLOUDS PASSING OVERHEAD...LEADING TO VARIABILITY IN BOTH VSBYS AND CEILINGS THIS MORNING. THE FOG AND LOW DECK SHOULD RISE THROUGH THE DAY TODAY...AS WINDS TURN NORTHERLY. AN MVFR DECK OF CLOUDS OVER NORTHWEST MINNESOTA AND NORTHERN ONTARIO WILL SLOWLY SINK SOUTH TODAY. AREAS ALONG THE SOUTH SHORE OF LAKE SUPERIOR WILL SEE SNOW SHOWERS DEVELOP LATER TONIGHT...LEADING TO IFR CONDITIONS IN SPOTS. && POINT TEMPS/POPS... DLH 28 12 20 4 / 20 20 10 10 INL 24 5 17 2 / 10 10 10 10 BRD 32 13 23 7 / 20 10 10 10 HYR 32 13 22 3 / 40 30 20 10 ASX 30 15 20 5 / 30 30 30 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 8 AM CST THIS MORNING FOR CROW WING- PINE-SOUTHERN AITKIN. WI...DENSE FOG ADVISORY UNTIL 8 AM CST THIS MORNING FOR BURNETT- WASHBURN. $$ CANNON/MELDE mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 256 AM CST MON FEB 25 2008 .DISCUSSION... A WEAK SHORTWAVE TROUGH IS FEATURED OVER NORTHWESTERN NEBRASKA THIS MORNING ON WATER VAPOR IMAGERY. ASSOCIATED RETURNS ON RADAR CORRELATE WITH ISENTROPIC UPGLIDE ON THE RUC 290K SURFACE. THIS AREA IS FORECAST TO SLIDE ACROSS SOUTHERN MN AND NORTHERN IA TODAY...WHICH CONCURS WITH THE NAM/GFS/SREF PROGGED 700MB LOW TRACK FROM SWRN SD ACROSS ERN NE AND SRN IA. MEASURABLE SNOWFALL POTENTIAL IS THEREFORE RESTRICTED TO EXTREME SOUTHERN MN...WITH MAX AMOUNTS IN THE CWA OF 1 TO 2 INCHES ALONG/SOUTH OF THE INTERSTATE 90 CORRIDOR. TRACE SNOWFALL AMOUNTS ARE EXPECTED ELSEWHERE. SNOWFALL ACCUMULATIONS WILL ALSO BE INHIBITED BY THE FACT THAT A PERIOD OF FREEZING RAIN WILL BE POSSIBLE ACROSS PORTIONS OF SOUTHWEST AND SOUTH CENTRAL MN THIS MORNING...WHERE 08Z TEMPERATURES WERE IN THE MID/UPPER 20S. NAM/GFS/RUC BUFKIT SOUNDINGS FOR REDWOOD FALLS ARE INDICATIVE OF THE FREEZING PRECIP POTENTIAL...WITH A TRANSITION TO SNOW COMMON BETWEEN 10 AND NOON. QPF DURING THIS TIMEFRAME IS LIGHT HOWEVER...SO MINIMAL ICE ACCUMULATIONS ARE ANTICIPATED. THE OTHER CONCERN THIS MORNING IS THE DENSE FOG THAT IS PLAGUING THE MIDSECTION OF THE FORECAST AREA...WHERE WIDESPREAD METARS ARE REPORTING SUB-QUARTER MILE VISIBILITIES. WILL LIKELY EXPAND THE ADVISORY INTO PORTIONS OF WEST CENTRAL WISCONSIN THIS MORNING...WHERE VISIBILITIES WILL LIKELY CONTINUE TO DECLINE IN THE TROUGH AXIS. CONVERSELY...WILL BE ABLE TO DROP A FEW COUNTIES OVER WEST CENTRAL MN...WHERE IMPROVEMENT IN VISIBILITIES IS OCCURRING DUE TO THE SHIFT TO NORTHWESTERLY WINDS AND INCREASE IN MID LEVEL CLOUD COVER. THE EXTENSIVE CLOUD COVER WILL MINIMIZE DIURNAL WARMING TODAY...ALTHOUGH ELEVATED OVERNIGHT MINIMUMS WILL CONTRIBUTE TO NEAR-NORMAL HIGHS BETWEEN 28 AND 34 DEGREES. A WEAK SECONDARY WAVE WILL PLUMMET ACROSS MN/WI ON TUESDAY...WHICH MAY GENERATE SOME FLURRIES. HIGHS WILL GENERALLY RANGE BETWEEN 10 AND 15 DEGREES BELOW NORMAL ON TUESDAY AND WEDNESDAY...WITH READINGS MAINLY BETWEEN 20 AND 25 DEGREES. A MORE NOTABLE SHORTWAVE AND SURFACE TROUGH WILL DIVE SOUTH FROM CANADA ON THURSDAY. 800MB-700MB FRONTOGENESIS SPREADS ACROSS THE CWA ON THURSDAY. GFS COBB OUTPUT GENERALLY INDICATES SNOWFALL ACCUMULATIONS BETWEEN ONE AND THREE INCHES FOR THE THURSDAY EVENT...WHICH SEEM REASONABLE. && .AVIATION.../06Z TAF ISSUANCE/ SPLIT WINDOW SATELLITE PICS (11-3.9 MICRON) SHOW A WELL DEFINED AREA OF LOW STATUS ACROSS SOUTHEAST MINNESOTA INTO WESTERN WISCONSIN WITH A SECOND SMALLER AREA TO THE SOUTHWEST OF KDLH. TO THE WEST OF THIS AREA...IFR CONDITIONS ARE COMMON FROM GROUND FOG VISIBILITY RESTRICTION. WE HAVE OPTED TO MAINTAIN OUR VERY PESSIMISTIC FORECAST FOR LIFR CONDITIONS IN STATUS AND FOG OVER OUR EASTERNMOST MN TAF SITES ALONG WITH OUR WISCONSIN SITES. SLOW IMPROVEMENT IS EXPECTED AFTER SUNRISE MONDAY WITH MORE SIGNIFICANT IMPROVEMENT LIKELY BY LATER AFTERNOON OR EARLY EVENING AS NORTHERLY FLOW INCREASES ACROSS THE AREA IN RESPONSE TO THE SURFACE LOW CROSSING IOWA. THIS WILL BRING DRIER AIR INTO SOUTHERN MN AND WESTERN WISCONSIN LATE IN THE FORECAST PERIOD. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR ANOKA-BENTON- BLUE EARTH-BROWN-CARVER-CHISAGO-DAKOTA-DOUGLAS-FARIBAULT- FREEBORN-GOODHUE-HENNEPIN-ISANTI-KANABEC-KANDIYOHI-LE SUEUR- MARTIN-MCLEOD-MEEKER-MILLE LACS-MORRISON-NICOLLET-POPE- RAMSEY-RICE-SCOTT-SHERBURNE-SIBLEY-STEARNS-STEELE-STEVENS- SWIFT-TODD-WASECA-WASHINGTON-WATONWAN-WRIGHT. WI...NONE. && $$ LS/WET mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1037 PM CST SUN FEB 24 2008 .DISCUSSION... DENSE FOG HAS DEVELOPED A LITTLE FARTHER SOUTH THAN THE PREVIOUS ADVISORY...WITH SAINT JAMES/FAIRMONT DOWN TO A QUARTER MILE AT THIS TIME. MOIST AIRMASS REMAINS OVER MUCH OF THE MINNESOTA PART OF THE FORECAST AREA...EXCEPT FOR THE SNOW FREE AREA ALONG THE MINNESOTA RIVER VALLEY. NAM/GFS/RUC BUFKIT PROFILES SUPPORTIVE OF FOG ACROSS EAST CENTRAL MINNESOTA AND INTO SOUTH CENTRAL...SO WITH CURRENT OBSERVATIONAL TRENDS AND SAID MODEL DATA...ELECTED TO EXPAND THE ADVISORY SOUTHWARD. EXPECTATION IS THAT THE FOG SHOULD IMPROVE BY 15Z...WITH THE GRADIENT INCREASING DUE TO THE DEEPENING SURFACE LOW MOVING THROUGH THE CENTRAL PLAINS/MID MISSISSIPPI VALLEY. THANKS FOR THE COORD ARX. && .AVIATION.../06Z TAF ISSUANCE/ SPLIT WINDOW SATELLITE PICS (11-3.9 MICRON) SHOW A WELL DEFINED AREA OF LOW STATUS ACROSS SOUTHEAST MINNESOTA INTO WESTERN WISCONSIN WITH A SECOND SMALLER AREA TO THE SOUTHWEST OF KDLH. TO THE WEST OF THIS AREA...IFR CONDITIONS ARE COMMON FROM GROUND FOG VISIBILITY RESTRICTION. WE HAVE OPTED TO MAINTAIN OUR VERY PESSIMISTIC FORECAST FOR LIFR CONDITIONS IN STATUS AND FOG OVER OUR EASTERNMOST MN TAF SITES ALONG WITH OUR WISCONSIN SITES. SLOW IMPROVEMENT IS EXPECTED AFTER SUNRISE MONDAY WITH MORE SIGNIFICANT IMPROVEMENT LIKELY BY LATER AFTERNOON OR EARLY EVENING AS NORTHERLY FLOW INCREASES ACROSS THE AREA IN RESPONSE TO THE SURFACE LOW CROSSING IOWA. THIS WILL BRING DRIER AIR INTO SOUTHERN MN AND WESTERN WISCONSIN LATE IN THE FORECAST PERIOD. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 9 AM CST MONDAY FOR ANOKA-BENTON-BLUE EARTH-BROWN-CARVER-CHISAGO-DAKOTA-DOUGLAS-FARIBAULT- FREEBORN-GOODHUE-HENNEPIN-ISANTI-KANABEC-KANDIYOHI-LE SUEUR- MARTIN-MCLEOD-MEEKER-MILLE LACS-MORRISON-NICOLLET-POPE- RAMSEY-RICE-SCOTT-SHERBURNE-SIBLEY-STEARNS-STEELE-STEVENS- SWIFT-TODD-WASECA-WASHINGTON-WATONWAN-WRIGHT. WI...NONE. && $$ 99/99/99 mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 521 AM CST SUN FEB 24 2008 .UPDATE...FOR 12Z AVIATION DISCUSSION BELOW && .DISCUSSION.../ISSUED 300 AM CST SUN FEB 24 2008/ IN THE NEAR TERM MAIN ISSUE IS WITH RAPIDLY DEVELOPING STRATUS AND FOG ACROSS CENTRAL MN. SOME VSBYS ON S PERIPHERY OF STRATUS HAVE DROPPED TO 1/2SM OR LESS. SOME DEVELOPING STRATUS HAS EVEN BEGUN TO SHOW IN E SODAK WITHIN THE PAST HOUR. RUC HAS CAPTURED THIS TO SOME EXTENT AND TRIES TO LIFT IT NE IN SWLY FLOW...BUT LOOKING LIKE MUCH OF CENTRAL MN WILL REMAIN UNDER CLOUDS AND SOME FOG THRU MUCH OF MORNING. REMAINDER OF AREA SHOUD SEE HAZY SUNSHINE TODAY WITH TEMPERATURES AGAIN UP A BIT FROM YESTERDAY WITH RELATIVELY MILD EARLY MORNING TEMPERATURES TO JUMP FROM. SOME CONCERN THAT SOME FOG MAY DEVELOP AGAIN COMING NIGHT MAINLY CENTRAL MN INTO WI IF CLOUDS DON`T THICKEN SOON ENOUGH. WILL LEAVE THIS TO DAY SHIFT TO ADD FOG IF NECESSARY. GFS AND ECMWF FAIRLY SIMILAR ON QPF OUTPUT FROM SYSTEM DIVING ACROSS IOWA ON MONDAY BRINGING QUARTER INCH QPF JUST INTO SC MN WHILE NAM BRINGS IT AS FAR NORTH AS MKT AND MVE AREA. EVEN WITH PWATS INCREASING ABOVE 1/2 INCH MONDAY MORNING QPF OUTPUT ON NAM SEEMS TOO HIGH. IT DOES BRING ISENTROPIC LIFT FARTHER NORTH INTO MN...BUT SIGNIFICANT LIFT IS BRIEF. DIFFICULT TO BUCK THE TREND OF LAST TWO MONTHS WITH SNOW TRACK REMAINING MAINLY SOUTH OF I-90 CORRIDOR IN OUR CWA. THE 2-4 INCH SNOW NOW IN GRIDS FOR SC MN FOR MONDAY/MONDAY EVENING LOOK REASONABLE AND DIDN`T CHANGE THEM. STILL LOOKS LIKE PRECIP COULD BEGIN LATE TONIGHT AS A MIX IN SW/SC MN WITH SIGNIFICANT NOSE ABOVE FREEZING ON GFS/NAM PROGGED SOUNDINGS. CLIPPER TYPE SYSTEM FOR THURSDAY IS FAIRLY CONSISTENT BETWEEN GFS AND ECMWF. BUMPED UP POPS A BIT...MAINLY NORTHERN CWA. STILL NO REAL COLD AIR TO TAP FOR COMING WEEK WITH TEMPERATURES REMAINING MILD WELL ABOVE 60 DEGREE NORTH LATITUDE. LOOKS LIKE FAIRLY TYPICAL LATE FEBRUARY READINGS. && .AVIATION.../12Z TAF ISSUANCE/ EXPECT THE AREA OF STRATUS AND FOG TO PERSIST ACROSS MUCH OF CENTRAL MN THIS MORNING...WITH VLIFR CONDITIONS AT KAXN/KSTC IMPROVING TO MVFR BY 18Z. EXPECT KRWF/KMSP/KRNH/KEAU TO EXPERIENCE MVFR VISIBILITIES THROUGH MUCH OF THE MORNING...WITH IMPROVEMENT TO VFR BY THIS AFTERNOON. AM SOMEWHAT CONCERNED THAT THE AREA OF STRATUS OVER EASTERN NEBRASKA MAY HOLD TOGETHER LONG ENOUGH TO AFFECT KEAU THIS AFTERNOON. FOR NOW...HAVE BROUGHT IN A PERIOD OF SCATTERED CLOUDS CIRCA 2K FEET. MODELS DO NOT HAVE A GOOD HANDLE ON THIS...SO WILL CONTINUE TO MONITOR SATELLITE TRENDS. REDEVELOPMENT OF LOW CLOUDS AND REDUCED VISIBILITIES IS EXPECTED THIS EVENING...AS A TROUGH OF LOW PRESSURE GLIDES ACROSS SOUTHERN MN AND IOWA. WIDESPREAD IFR CONDITIONS ARE LIKELY AFTER 06Z MONDAY...ALTHOUGH THE ONLY TAF SITE THAT MAY EXPERIENCE SNOW BEFORE THE END OF THE PERIOD IS KRWF. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR BENTON- CHIPPEWA-DOUGLAS-KANABEC-KANDIYOHI-LAC QUI PARLE-MILLE LACS- MORRISON-POPE-SHERBURNE-STEARNS-STEVENS-SWIFT-TODD. WI...NONE. && $$ BAP/LS mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 300 AM CST SUN FEB 24 2008 .DISCUSSION... IN THE NEAR TERM MAIN ISSUE IS WITH RAPIDLY DEVELOPING STRATUS AND FOG ACROSS CENTRAL MN. SOME VSBYS ON S PERIPHERY OF STRATUS HAVE DROPPED TO 1/2SM OR LESS. SOME DEVELOPING STRATUS HAS EVEN BEGUN TO SHOW IN E SODAK WITHIN THE PAST HOUR. RUC HAS CAPTURED THIS TO SOME EXTENT AND TRIES TO LIFT IT NE IN SWLY FLOW...BUT LOOKING LIKE MUCH OF CENTRAL MN WILL REMAIN UNDER CLOUDS AND SOME FOG THRU MUCH OF MORNING. REMAINDER OF AREA SHOUD SEE HAZY SUNSHINE TODAY WITH TEMPERATURES AGAIN UP A BIT FROM YESTERDAY WITH RELATIVELY MILD EARLY MORNING TEMPERATURES TO JUMP FROM. SOME CONCERN THAT SOME FOG MAY DEVELOP AGAIN COMING NIGHT MAINLY CENTRAL MN INTO WI IF CLOUDS DON`T THICKEN SOON ENOUGH. WILL LEAVE THIS TO DAY SHIFT TO ADD FOG IF NECESSARY. GFS AND ECMWF FAIRLY SIMILAR ON QPF OUTPUT FROM SYSTEM DIVING ACROSS IOWA ON MONDAY BRINGING QUARTER INCH QPF JUST INTO SC MN WHILE NAM BRINGS IT AS FAR NORTH AS MKT AND MVE AREA. EVEN WITH PWATS INCREASING ABOVE 1/2 INCH MONDAY MORNING QPF OUTPUT ON NAM SEEMS TOO HIGH. IT DOES BRING ISENTROPIC LIFT FARTHER NORTH INTO MN...BUT SIGNIFANT LIFT IS BRIEF. DIFFICULT TO BUCK THE TREND OF LAST TWO MONTHS WITH SNOW TRACK REMAINING MAINLY SOUTH OF I-90 CORRIDOR IN OUR CWA. THE 2-4 INCH SNOW NOW IN GRIDS FOR SC MN FOR MONDAY/MONDAY EVENING LOOK REASONABLE AND DIDN`T CHANGE THEM. STILL LOOKS LIKE PRECIP COULD BEGIN LATE TONIGHT AS A MIX IN SW/SC MN WITH SIGNIFICANT NOSE ABOVE FREEZING ON GFS/NAM PROGGED SOUNDINGS. CLIPPER TYPE SYSTEM FOR THURSDAY IS FAIRLY CONSISTENT BETWEEN GFS AND ECMWF. BUMPED UP POPS A BIT...MAINLY NORTHERN CWA. STILL NO REAL COLD AIR TO TAP FOR COMING WEEK WITH TEMPERATURES REMAINING MILD WELL ABOVE 60 DEGREE NORTH LATITUDE. LOOKS LIKE FAIRLY TYPICAL LATE FEBRUARY READINGS. && .AVIATION.../06Z TAF ISSUANCE/ MOISTURE FROM THE SNOWMELT THAT OCCURRED OVER SOUTHWEST MN...AND ADJACENT AREAS SOUTH AND WEST DURG THE DAY ON SATURDAY ALONG WITH A MOIST LOW LEVEL AIRFLOW(WITH DEWPOINTS EXCEEDING 20 DEGREES)...WILL CONTINUE TO CONTRIBUTE TO THE FORMATION OF MVFR TO IFR CONDITIONS DUE TO FOG OVR THE TAF SITES TONIGHT AND SUNDAY MORNING. LIGHT SOUTHEAST-SOUTH SURFACE WINDS WILL CONTINUE TO ADVECT ACROSS THE SNOW COVERED AND CONDENSE JUST NORTH OF SNOW FIELD. VISIBILITIES BETWEEN 3-5 MILES IN FOG WILL BE COMMON THRU 17Z UTC SUNDAY MORNING. SKIES WILL REMAIN CLEAR OVERNIGHT WITH THE EXCEPTION OF SCATTERED TO BROKEN CEILING UNDER ONE THOUSAND FEET AGL IN STRATUS BEFORE DAYBREAK SUNDAY. LOW CLOUDS ARE EXPECTED TO BREAKUP AND DISSIPATE BY LATE MORNING. MEANWHILE...HIGH CLOUDS WILL CONTINUE TO SPREAD EAST IN ADVANCE OF THE APPROACHING LOW PRESSURE SYSTEM OVER THE HIGH PLAINS. VFR FLYING CONDS ARE EXPECTED TO PREVAIL FOR THE BALANCE OF THE PERIOD. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ BAP/JVM mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 930 PM CST MON FEB 25 2008 .UPDATE... THE LATEST SFC ANALYSIS FROM 03Z SUGGESTS THE SFC LOW IS LOCATED JUST ENE OF KJEF ALONG THE MISSOURI RIVER. THIS IS A BIT FUTHER NORTH THAN EVEN THE NEWEST MODEL GUIDANCE. PRECIPITATION IN ADVANCE OF THE SFC LOW AND WARM SECTOR REMAINS MORE SCATTERED IN NATURE AS THE MID LEVEL DRY SLOT HAS PROGRESSED INTO IL. THE DEFORMATION ZONE WHICH LOOKED PRETTY ROBUST LATE THIS AFTERNOON ACROSS IA HAS WEAKENED IN OVERALL INTENSITY BUT IS STILL PRODUCING SOME MESOSCALE BANDS OF MODERATE SNOW FROM CENTRAL IA INTO NRN IL...BUT ONLY LIGHT SNOW FURTHER WEST AND SOUTHWEST INTO KS. ITS MAJOR AXIS HAS SHIFTED SEWD OVER THE LAST 4-5 HOURS IN ASSOCIATION WITH THE EWD MOVEMENT OF THE PLAINS SHRTWV/VORT MAX. RAIN HAS CHANGED TO SNOW OVER THE LAST HR OR TWO ACROSS NORTHERN PORTIONS OF KNOX AND LEWIS COUNTY. STRONG AND GUSTY WINDS OF 35-40 MPH HAVE BEEN OCCURING FROM NW MO INTO THE CENTRAL PLAINS IN THE WAKE OF THE SFC LOW. THE 18Z MODEL GUIDANCE AND THE 00Z NAM/RUC HAVE BACKED OFF THE INTENSITY OF THE MESOSCALE FORCING AND VERTICAL MOTION ASSOCIATED WITH THE DEFORMATION ZONE AS IT SWINGS SEWD ACROSS THE AREA TONIGHT. ACCORDINGLY THERE IS LESS QPF AS WELL. GIVEN THE LOCATION OF THE MID LEVEL CIRCULATION IN WEST CENTRAL IL ATTM AND LACK OF UPSTREAM AMPLIFICATION...THIS APPREARS REASONABLE. I THINK THERE WILL BE STRONG WINDS AND SOME SNOW...BUT UNLESS THE DEF ZONE REDEVELOPS AND INTENSIFIES...THE TRENDS TONIGHT COUPLED WITH THE NEWEST GUIDANCE SUGGESTS OUR CURRENT SNOW AMOUNTS ARE A BIT ON THE HIGH SIDE. OUTSIDE OF A SNOW BURST OR TWO THE PROBABILITY OF GETTING VSBYS WITH SNOW AND BLOWING SNOW OF 1/4SM OR LESS LOOK PRETTY LOW AS WELL. I`M NOT VERY EXCITED ABOUT THE HEADLINES NOW AS I WAS EARLIER WHEN I SAW THE 18Z RUC AND CGEM...HOWEVER I`M A BIT HESITANT TO DROP THE ADVSRY ALL TOGETHER DUE TO AFOREMENTIONED POTENTIAL FOR A BURST...WHICH WOULD BE NEAR THE MORNING RUSH HR IN THE STL AREA. ATTM MY PLANS ARE TO LOWER THE SNOW ACCUMULATIONS EXCEPT FOR NE MO/WEST CENTRAL IL AND TONE THE WORDING DOWN A BIT. THE MID SHIFT WILL NEED TO CLOSELY EVALUATE THE NEED FOR CONTINUING THE HEADLINES. GLASS && .DISCUSSION... OBVIOUSLY...MAIN CONCERN FOR THE SHORT TERM IS UPCOMING WX TRENDS FOR TNGT AND TUE. AS WAS FEARED YSTDA...EACH SUCCESSIVE MODEL RUN CONTS TO TREND A BIT FURTHER S WITH THE LOW...WHICH IS CURRENTLY JUST EAST OF MKC. AS THE LOW TRACKS JUST S OF STL THIS EVENING LARGE BAND OF PCPN OCRG N OF THE LOW FROM SE NE INTO S IA WL ALSO DROP SE...WITH ADDITIONAL DVLPMT OCRG OVR THE AREA AS INITIALLY DRY LO LVLS IS FCST TO SATURATE QUICKLY. AS FAR AS THE CHGOVR TO SNOW IS CONCERNED...OUR THINKING IS THAT SNW WL BGN ERH THIS EVENING ARND UIN...ABT MIDN NR COU...WITH A RPD CHGOVR OCRG FROM STL AND SE IN THE 09Z-12Z TIME FRAME. ONCE THE CHGOVR TO SNOW OCCCURS..CONSENSUS QPF FROM MODELS SUGGESTS THAT ACCUM IN THE 1-3 INCH RANGE CAN BE EXPECTED THRU MIDDAY TUE ALG AND E OF A MEXICO...WARRENTON...NASHVILLE IL LN...WITH THE HIGHEST ACCUMULATIONS OVR CNTRL IL SECTION OF OUR FA. STG NW WNDS GUSTING TO ARND 40 MPH WL BE CAUSING BLOWING AND DRIFTING...AND THINK THAT ONCE THE CHGOVR TO SNOW OCRS CONDS WL DETERIORATE QUICKLY. HV OPTED TO ISSUE A SNOW AND BLOWING SNOW ADVISORY FOR THE ABV AREAS DUE TO THIS THRT...WITH THE ONSET OF THE ADVSRY TIED TO THE START TIMES OF THE SNOW AS GIVEN IN THE FIRST PARAGRAPH OF THE AFD. CERTAINLY...THE SGFNT PCPN WL BE WINDING DOWN TMRW AFTN...WITH WNDS SLOWLY SUBSIDING DURG THE LT AFTN AND EVENING HRS AS SFC RDG PUSHES E AND GRADIENT OVR REGION BGNS TO RELAX. TEMPS WL BGN DROPPING TNGT IN THE WAKE OF THE SFC LOW...AND SHUD CONTINUE THEIR DROP MOST OF THE DAY TUE AND INTO TUE NGT. FOR THE REMAINDER OF THIS FCST PKG...WED-SUN...GOING TRENDS WL GENLY REMAIN UNCHGD AS MODEL SOLNS CONT TO SHOW GOOD RUN TO RUN CONSISTENCY. HV KEPT MAX TEMPS TWD THE LO SIDE OF GUIDANCE ON WED...WITH TEMPS TRENDING TO NR OR SLGLTLY ABV NORMAL THU-SUN. A THRT OF PCPN WL CONT THU NGT AND FRI WITH NXT SYS...BUT WITH MOST OF THE DYNAMICS RMNG WELL N OF AREA THINK POPS WL BE LO. AND COOLING BHND SYSTEM JUST CLIPPING AREA NO BIG CHG IS TEMPS IS EXPECTED WITH PASSAGE OF FNT. STGR SYSTEM DOES APR IN THE OFFING BY MONDAY...WITH A DROP IN TEMPS AT THAT TIME. TRUETT && .AVIATION... FOR THE 00Z TAFS... A WHOLE HOST OF PROBLEMS FOR AVIATION INTERESTS TONIGHT. SYSTEM MOVING FROM GREAT PLAINS THROUGH THE MID-MISSISSIPPI VALLEY TONIGHT WILL SPREAD IFR/LIFR CIGS ACROSS THE AREA TONIGHT...WITH POSSIBLE SNOW AND BLOWING SNOW ON THE NORTHWEST/WEST SIDE OF THE LOW. WINDS SHOULD INCREASE TO 20-30KTS...PERHAPS WITH EVEN HIGHER GUSTS OVERNIGHT TONIGHT AS THE SYSTEM MOVES INTO THE TENNESSEE VALLEY. THERE IS SOME QUESTION AS TO HOW MUCH SNOW WILL FALL TONIGHT. LATEST GUIDANCE ISN`T AS ROBUST WITH THE SNOWFALL AS PREVIOUS RUNS...BUT NOT QUITE READY TO MAKE WHOLESALE CHANGES TO THE FORECAST BASED ON ONE RUN OF THE MODELS. WILL CONTINUE TO MONITOR AND REEVALUATE AS NECESSARY AS THE SYSTEM EVOLVES THIS EVENING. CARNEY && .LSX WATCHES/WARNINGS/ADVISORIES... MO...SNOW AND BLOWING SNOW ADVISORY FROM MIDNIGHT TONIGHT TO 12 PM CST TUESDAY FOR AUDRAIN-LINCOLN-MONROE-MONTGOMERY-PIKE- RALLS. SNOW AND BLOWING SNOW ADVISORY FROM 3 AM TO 12 PM CST TUESDAY FOR FRANKLIN-JEFFERSON-ST. CHARLES-ST. LOUIS-ST. LOUIS CITY- WARREN. SNOW AND BLOWING SNOW ADVISORY UNTIL 12 PM CST TUESDAY FOR KNOX- LEWIS-MARION-SHELBY. IL...SNOW AND BLOWING SNOW ADVISORY FROM MIDNIGHT TONIGHT TO 12 PM CST TUESDAY FOR PIKE IL. SNOW AND BLOWING SNOW ADVISORY FROM 3 AM TO 12 PM CST TUESDAY FOR BOND IL-CALHOUN IL-CLINTON IL-FAYETTE IL-GREENE IL- JERSEY IL-MACOUPIN IL-MADISON IL-MARION IL-MONROE IL- MONTGOMERY IL-RANDOLPH IL-ST. CLAIR IL-WASHINGTON IL. SNOW AND BLOWING SNOW ADVISORY UNTIL 12 PM CST TUESDAY FOR ADAMS IL-BROWN IL. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1140 PM CST SAT FEB 23 2008 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... MESOSCALE FEATURES NOT BEING HANDLED PARTICULARLY WELL AS RADAR LOOPS SHOW A VORTICITY MAX OVER CENTRAL KS WEST OF HUT AND ANOTHER ALONG THE CENTRAL OK/KS BORDER. MIXED PRECIPITATION OCCURRING AHEAD OF BOTH FEATURES. APPEARS 21Z RUC BOUNDARY LAYER TEMPERATURES HAVE THE BEST HANDLE ON THE POCKET OF SUBFREEZING TEMPERATURES ASSOCIATED WITH THE MIXED PRECIPITATION. BANDED PRECIPITATION EXPECTED ACROSS THE FAR SOUTHWESTERN COUNTIES THIS EVENING. CURRENT THINKING IS 1-2 INCHES OF SNOW/SLEET...JUST ENOUGH TO MAKE IT SLIPPERY TO WARRANT A WINTER WEATHER ADVISORY. WILL BE ISSUING ONE SHORTLY. MJ && .PREV DISCUSSION... /339 PM CST SAT FEB 23 2008/ SHORT TERM (TONIGHT THROUGH SUNDAY NIGHT)... MAIN CONCERN IN THE SHORT TERM IS WITH APPROACHING SHORT WAVE TONIGHT. MIXED BAG OF PRECIPITATION HAS BEEN OCCURRING ACROSS KANSAS WITH THE SYSTEM...BUT THINKING THAT EVAPORATIVE COOLING AS THIS SYSTEM HEADS INTO SOUTHWEST PORTIONS OF FORECAST AREA THIS EVENING SHOULD HELP TO COOL COLUMN IN THE 900 TO 800 MB RANGE ENOUGH TO PROMOTE A FAIRLY QUICK CHANGE OVER FROM RAIN TO SNOW. SURFACE TEMPERATURES TODAY IN AREAS SOUTH OF KANSAS CITY WERE IN THE MIDDLE 30S...SO GROUND SHOULD BE ABLE TO HANDLE SOME COLD RAIN INITIALLY. WILL NOT ISSUE AN ADVISORY AT THIS POINT...SINCE MAINLY ANTICIPATING A WET SNOW OF AN INCH OR LESS WITH THIS SYSTEM. BUT IF ICING STARTS TO OCCUR...WE MAY NEED TO GO WITH SOME HEADLINES. 18Z RUC AND WRF MODELS SHOWING QUITE A BIT OF MID LEVEL DRY AIR HOLDING OVER NORTHERN MISSOURI THIS EVENING...WITH A STEEP GRADIENT AS YOU GO SOUTH OF THE MISSOURI RIVER. WILL LIMIT NORTHERN EXTENT OF ANY POPS BASED ON THIS. GREATEST SATURATION...WILL STAY IN AREAS ALONG AND SOUTH OF 50 HIGHWAY. 12Z GFS WAS LITTLE FURTHER NORTH WITH IS RH FIELDS...SO WILL HEDGE AND LEAVE SOME SLIGHT CHANCE POPS AS FAR NORTH AS AN ATCHISON KANSAS TO CARROLLTON TO FAYETTE LINE BUT KEEP CHANCE AND HIGHER POPS TO AREAS SOUTH OF A LEAVENWORTH KANSAS TO BOONVILLE LINE. OTHER CONCERN IS FOG POTENTIAL LATE TONIGHT. WITH SOME SNOW MELT NORTH TODAY...SEEING THE SURFACE DEWPOINTS REMAINING IN THE MIDDLE 20S. THIS SHOULD SUPPORT AT LEAST SOME LIGHT FOG DEVELOPMENT TONIGHT...AND IF SKIES CAN CLEAR IN THE NORTHERN AREAS...WITH LIGHT WINDS EXPECTED...MAY SEE POCKETS OF DENSE FOG. FURTHER SOUTH...IF DRIER AIR CAN WORK IN BEHIND THIS WAVE AND HELP TO CLEAR THE SKIES LATE TONIGHT IN EASTERN KANSAS AND WESTERN MISSOURI...FOG DEVELOPMENT WILL ALSO BE A CONCERN. DURING THE DAY ON SUNDAY UPPER RIDGE WILL BE BUILDING OVER THE CENTRAL PLAINS...WITH A STRENGTHENING RETURN FLOW BY SUNDAY EVENING. WILL KEEP TEMPERATURES A LITTLE COOLER THAN GUIDANCE ON SUNDAY...ESPECIALLY IN AREAS WITH SNOW COVER. SUNDAY NIGHT THOUGH SHOULD BE PRETTY MILD. FOG SOMEWHAT OF A CONCERN WITH THIS WARM AIR OVERRUNNING THE COLD WET GROUND...BUT TOO MUCH UNCERTAINTY TO WARRANT MENTIONING IT IN THE FORECAST AT THIS POINT. PC MEDIUM RANGE (MONDAY-SATURDAY)... PRECIPITATION CHANCES WILL BE ON THE INCREASE BY THE BEGINNING OF THE WEEK AS THE NEXT SHORT WAVE TROUGH SWINGS ACROSS THE AREA. HEIGHT FALLS SHOULD BE OVERSPREADING THE CENTRAL PLAINS BY MONDAY MORNING WITH A DEEPENING SFC LOW SLIDING ACROSS NEBRASKA. WITH SOUTHWESTERLY H85 WINDS OF 50KTS WARMING H85 TEMPS TO 5-10C BY MONDAY MORNING ALONG WITH PERSISTENT SOUTHERLY SFC FLOW...EXPECTING SFC TEMPS TO CLIMB ABOVE SEASONAL NORMS...LIKELY REACHING THE LOWER 50S ACROSS THE SOUTHERN COUNTIES. HOWEVER...MAX TEMPS WILL REMAIN TRICKY AS SFC BAROCLINIC BOUNDARY WILL BARREL THROUGH THE AREA DURING THE AFTERNOON HOURS. AHEAD OF THE FRONT...WEAK TO MODERATE ISENTROPIC LIFT MAY SPARK SOME SCATTERED SHOWERS DURING THE DAY AS ATMOSPHERIC PROFILES SUGGEST ALL RAIN TO START OUT WITH THE AREA INITIALLY IN THE WARM SECTOR. AS THE SFC BOUNDARY MOVES THROUGH THE AREA...STRONG CAA SHOULD TAKE SHAPE ON THE BACK SIDE AS NORTHWEST SFC FLOW WILL ADVECT IN MUCH COLDER TEMPS. IN ADDITION...COLDER MID LEVEL TEMPS WILL HELP COOL THE ATMOSPHERIC COLUMN SO THAT A GRADUAL CHANGEOVER TO SNOW SHOULD TAKE PLACE DURING THE AFTERNOON AND EVENING HOURS MONDAY. RAISED POPS THROUGH THE EVENT...MAINLY ACROSS THE NORTHERN HALF OF THE CWA...HOWEVER KEPT WORDING IN THE CHC CATEGORY WITH DIFFERENCES CONTINUING AMONG MODEL SOLUTIONS. APPEARS BULK OF THE PRECIP WILL REMAIN NORTH OF THE AREA ACROSS IOWA SO HAVE KEPT SNOW AMOUNTS CONSERVATIVE FOR THE TIME BEING. SECONDARY SHORT WAVE TROUGH SHOULD BRING A REINFORCING SHOT OF COLDER AIR TUESDAY AS IT TRANSLATES SOUTHEASTWARD WITHIN DEVELOPING HIGH AMPLITUDE FLOW. STOUT UPPER RIDGING WILL BECOME ESTABLISHED ACROSS THE WESTERN US BY TUESDAY AFTERNOON AND EVENING AS ANOTHER SHOT OF CANADIAN AIR SPILLS SOUTHWARD. UPPER FLOW PATTERN GRADUALLY FLATTENS A BIT THROUGH THE REMAINDER OF THE WEEK WHICH SHOULD HELP MODERATE TEMPS. OTHERWISE...KEPT THE MAJORITY OF THE REMAINDER OF THE FORECAST DRY WITH THE EXCEPTION OF THE NORTHEAST COUNTIES FOR THURSDAY NIGHT AS A FAST MOVING SYSTEM SWINGS ACROSS THE AREA. DEROCHE && .AVIATION... FOR THE 06Z TAF A FEW LINGERING FLURRIES POSSIBLE AT THE MKC TAF THROUGH 08Z. OTHERWISE...MVFR VISIBILITIES DUE TO LIGHT FOG DEVELOPING AFTER 08Z. MVFR/IFR CEILINGS UPSTREAM OVER NORTH CENTRAL KS EXPECTED TO SHIFT EAST OVERNIGHT AND ARRIVE AFTER 10Z. THESE LOW CEILINGS WILL BE STUBBORN TO GET RID OF AND COULD LAST THROUGH THE MORNING HOURS BEFORE BOUNDARY LAYER WINDS INCREASE OUT OF THE SOUTHWEST AND MIX OUT THE LOW CLOUDS. VFR CONDITIONS THEN EXPECTED TO PERSIST AFTER 18Z THROUGH THE REST OF THE FORECAST. MJ && .EAX WATCHES/WARNINGS/ADVISORIES... MO...WINTER WEATHER ADVISORY UNTIL 4 AM SUNDAY FOR MOZ043-MOZ044- MOZ045-MOZ053-MOZ054. KS...WINTER WEATHER ADVISORY UNTIL 4 AM SUNDAY FOR KSZ057-KSZ060. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 1123 PM CST SAT FEB 23 2008 .UPDATE... WILL BE SENDING OUT ANOTHER UPDATE SOON. LOOKS LIKE HEAVIEST BAND OF SNOW SETTING UP AND WILL BE CENTERED ALONG A VIENNA TO DE SOTO TO SPARTA LINE OR JUST A TAD NORTH. ALONG THAT AXIS AND 20NM OR SO EITHER SIDE I THINK 2-3 INCHES IS A GOOD BET WITH SOME ISOLD 4 INCH AMOUNTS NOT OUT OF THE QUESTION. AMOUNTS ACROSS THE STL METRO COULD RANGE FROM 1/2 INCH NORTH TO 2 INCHES SOUTH. WILL BE EXPANDING THE ADVSRY A BIT NORTH. GLASS && .DISCUSSION... THE EVENING UA DATA ALONG WITH SATELLITE AND WATER VAPOR IMAGERY SHOW THE PLAINS SYSTEM IS A BIT STRONGER THAN PREVIOUSLY ANTICIPATED WITH CLOSED LOW AND MID LEVEL CIRCULATIONS. THE PRECIPITATION SHIELD IS WELL DEVELOPED AND QUITE EXPANSIVE WITH A NICE COMMA STRUCTURE EVIDENT IN BOTH RADAR AND SATELLITE IMAGERY. THE 18Z MODEL RUNS AND NEW 00Z RUC AND 00Z NAM INDICATES THE SYSTEM WILL PEAK IN INTENSITY BTWN 06-09Z AND THEN BEGIN SLOWLY WEAKENING. PROGGED SYSTEM MOVEMENT OVER THE NEXT 6-9H AND EXTRAPOLATION WOULD BRING THE HEAVIEST BAND OF PCPN JUST SOUTH OF AN AXIS FROM CALIFORNIA TO UNION TO WATERLOO WHERE SEVERAL INCHES OF SNOW ARE EXPECTED...WITH THE NORTHERN EXTENT OF SNOW NOW EXPECTED NORTH OF I-70. PTYPE WILL BE AN ISSUE AT TIMES THIS EVENING. WARM AIR ALOFT WAS PRESENT ACROSS SRN MO AND EVEN A 0130Z ACARS SOUNDING OUT OF LAMBERT SHOWED A NARROW WARM WEDGE ALOFT PEAKING AT +2 DEGC CENTERED NEAR 800 MB. THERE HAVE ALREADY BEEN REPORTS OF SOME SLEET AND FREEZING RAIN IN THE OZARKS AND SLEET HAS BEEN NOTED IN WEST CENTRAL MO AS WELL. THESE ISSUES WILL PERSIST UNTIL EVAPORATIVE COOLING WINS OUT LATER TONIGHT. AROUND ST LOUIS EAST AND NORTHEAST I THINK THEY WILL BE LESS OF AN ISSUE ALTHO THERE CUD BE SOME SLEET BEFORE CHANGING TO ALL SNOW. FURTHER SOUTH THE LONGER PERIOD OF MIXED PCPN HAS PROMPTED AN ADVSRY THRU 12Z. POPS WERE INCREASED INVOF OF I-70 SWD TO CATEGORICAL. FURTHER UPDATES MAY BE NEEDED BEFORE THE EVENING IS DONE. KUDOS TO THE CANADIAN MODEL WHOSE QPF HAS NAILED THE LAST 2 SYSTEMS. GLASS && .AVIATION... FOR THE 06Z TAFS... COMMA SHAPED AREA OF SNOW WILL MOVE ACROSS KCOU AND METRO TAF SITES OVERNIGHT WITH IFR CONDITIONS LIKELY IN THE HEAVIEST BANDS OF SNOW. SNOW TAPERS OFF BY 12Z WITH IMPROVING CONDITIONS BY AFTERNOON. CVKING && .LSX WATCHES/WARNINGS/ADVISORIES... MO...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR CRAWFORD-IRON- MADISON-REYNOLDS-ST. FRANCOIS-STE. GENEVIEVE-WASHINGTON. IL...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR RANDOLPH IL. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 1117 PM CST SAT FEB 23 2008 .DISCUSSION... THE EVENING UA DATA ALONG WITH SATELLITE AND WATER VAPOR IMAGERY SHOW THE PLAINS SYSTEM IS A BIT STRONGER THAN PREVIOUSLY ANTICIPATED WITH CLOSED LOW AND MID LEVEL CIRCULATIONS. THE PRECIPITATION SHIELD IS WELL DEVELOPED AND QUITE EXPANSIVE WITH A NICE COMMA STRUCTURE EVIDENT IN BOTH RADAR AND SATELLITE IMAGERY. THE 18Z MODEL RUNS AND NEW 00Z RUC AND 00Z NAM INDICATES THE SYSTEM WILL PEAK IN INTENSITY BTWN 06-09Z AND THEN BEGIN SLOWLY WEAKENING. PROGGED SYSTEM MOVEMENT OVER THE NEXT 6-9H AND EXTRAPOLATION WOULD BRING THE HEAVIEST BAND OF PCPN JUST SOUTH OF AN AXIS FROM CALIFORNIA TO UNION TO WATERLOO WHERE SEVERAL INCHES OF SNOW ARE EXPECTED...WITH THE NORTHERN EXTENT OF SNOW NOW EXPECTED NORTH OF I-70. PTYPE WILL BE AN ISSUE AT TIMES THIS EVENING. WARM AIR ALOFT WAS PRESENT ACROSS SRN MO AND EVEN A 0130Z ACARS SOUNDING OUT OF LAMBERT SHOWED A NARROW WARM WEDGE ALOFT PEAKING AT +2 DEGC CENTERED NEAR 800 MB. THERE HAVE ALREADY BEEN REPORTS OF SOME SLEET AND FREEZING RAIN IN THE OZARKS AND SLEET HAS BEEN NOTED IN WEST CENTRAL MO AS WELL. THESE ISSUES WILL PERSIST UNTIL EVAPORATIVE COOLING WINS OUT LATER TONIGHT. AROUND ST LOUIS EAST AND NORTHEAST I THINK THEY WILL BE LESS OF AN ISSUE ALTHO THERE CUD BE SOME SLEET BEFORE CHANGING TO ALL SNOW. FURTHER SOUTH THE LONGER PERIOD OF MIXED PCPN HAS PROMPTED AN ADVSRY THRU 12Z. POPS WERE INCREASED INVOF OF I-70 SWD TO CATEGORICAL. FURTHER UPDATES MAY BE NEEDED BEFORE THE EVENING IS DONE. KUDOS TO THE CANADIAN MODEL WHOSE QPF HAS NAILED THE LAST 2 SYSTEMS. GLASS && .AVIATION... FOR THE 06Z TAFS... COMMA SHAPED AREA OF SNOW WILL MOVE ACROSS KCOU AND METRO TAF SITES OVERNIGHT WITH IFR CONDITIONS LIKELY IN THE HEAVIEST BANDS OF SNOW. SNOW TAPERS OFF BY 12Z WITH IMPROVING CONDITIONS BY AFTERNOON. CVKING && .LSX WATCHES/WARNINGS/ADVISORIES... MO...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR CRAWFORD-IRON- MADISON-REYNOLDS-ST. FRANCOIS-STE. GENEVIEVE-WASHINGTON. IL...WINTER WEATHER ADVISORY UNTIL 6 AM CST SUNDAY FOR RANDOLPH IL. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 1108 AM MST MON FEB 25 2008 UPDATED AVIATION DISCUSSION .UPDATE... TODAY...THE LARGE SCALE PATTERN HAS AN UPPER LEVEL HIGH PRESSURE RIDGE BUILDING OVER THE WEST COAST WHILE A BROAD LOW PRESSURE TROF MOVES EAST INTO THE MIDWEST. THIS LEAVES THE ZONES BENEATH NORTHWEST FLOW ALOFT. THE MAIN INTEREST FOR TODAY IS A VORT MAX MOVING THROUGH THIS FLOW...ACROSS NORTHWEST MONTANA INTO THE SOUTHWEST ZONES. SOME GOOD LIFT AND MOISTURE WILL ALLOW FOR A GOOD BURST OF SNOW AS THIS FEATURE MOVES SOUTHWARD BUT IT WILL MOVE RAPIDLY AND THE HEAVIEST SNOW SHOULD BE SHORT LIVED. TO THE NORTH...UPSLOPE FLOW IS WEAK AND WILL CONTINUE TO WEAKEN. HAVE DROPPED POPS IN THE NORTH FOR THE REMAINDER OF THIS MORNING AND THIS AFTERNOON. WILL LEAVE THE ADVISORY IN PLACE BUT PLAN ON ALLOWING IT TO EXPIRE AT NOON. ZELZER && .PREV DISCUSSION... /ISSUED 606 AM MST MON FEB 25 2008/ UPDATE... FORECAST PACKAGE AND HAZARDOUS WEATHER OUTLOOK ARE BEING UPDATED TO ACCOUNT FOR HIGHER SNOW AMOUNTS THIS MORNING OVER SOUTHWEST MONTANA...AS SNOW BANDS WORK THEIR WAY SOUTHEASTWARD AHEAD OF A FAST-MOVING...MID-LEVEL SHORTWAVE TROUGH. OVER SOUTHWEST MONTANA FOR THIS MORNING...ADDITIONAL SNOW ACCUMULATIONS OF 1 TO 2 INCHES ARE EXPECTED OVER THE VALLEYS...WITH 2 TO 4 INCHES IN THE MOUNTAINS. COHEN/BRUSDA && .AVIATION... UPDATED 1800Z. AN UPPER LEVEL DISTURBANCE WILL CONTINUE TO TRACK SOUTHEASTWARD ACROSS SOUTHWEST MT THIS AFTERNOON WITH A RIDGE OF HIGH PRESSURE BUILDING IN BEHIND THE SYSTEM TONIGHT THOUGHT TOMORROW. SNOW WILL CONTINUE ACROSS MUCH OF CENTRAL AND SW MT THROUGH THIS AFTERNOON...MAINLY FROM KHLN TO KBZN AND SOUTH. NORTH OF THIS...EXPECT A FEW FLURRIES WITH MAIN IMPACT BEING CONTINUED LOW CEILINGS AND FOG. EXPECT SLOW IMPROVEMENT TO THESE AREAS THIS AFTERNOON WITH BETTER IMPROVEMENT THIS EVENING. CLEARING TONIGHT LOW ALLOW FOR THE DEVELOPMENT OF VALLEY FOG AT SOME LOCATIONS. HOENISCH && .PREV DISCUSSION... /ISSUED 500 AM MST MON FEB 25 2008/ BROAD UPPER LEVEL TROUGH OVER THE CENTRAL CONUS WILL CONTINUE TO PROGRESS EASTWARD TODAY...AS NORTHWESTERLY FLOW ALOFT SETS UP OVER THE REGION. CURRENT IR AND WATER VAPOR SATELLITE IMAGERY INDICATE A RATHER COMPACT MID LEVEL SHORTWAVE TROUGH QUICKLY MOVING SOUTHEASTWARD OVER MONTANA AND IDAHO. MODELS PICK UP ON THIS FEATURE WELL...AND TAKE IT THROUGH THE SOUTHWEST HALF OF MONTANA THIS MORNING. WITH MORE THAN ADEQUATE DEEP MOISTURE ALREADY IN PLACE...LIFT ASSOCIATED WITH THIS SYSTEM WILL PRODUCE AREAS OF SNOW SOUTH OF A CHOTEAU-GREAT FALLS-LEWISTOWN LINE. TO THE NORTH OF THIS LINE...RUC AND OTHER MODELS ARE SHOWING VERY LITTLE...IF ANY...ADDITIONAL SNOWFALL...AS THE BULK OF THE UPPER LEVEL ENERGY RIDES SOUTH OF THOSE AREAS. THUS...THE NORTHERN PORTIONS OF THE SNOW ADVISORY HAVE BEEN CANCELLED...WITH THE REST OF THE SNOW ADVISORY REMAINING IN EFFECT UNTIL NOON MST TODAY. SOUTH OF THE CHOTEAU-GREAT FALLS-LEWISTOWN LINE...UP TO AN INCH OF NEW SNOW WILL BE POSSIBLE OVER THE PLAINS AND VALLEYS...WITH UP TO 2 INCHES OVER THE MOUNTAINS...WITH WEAK UPSLOPE FLOW CONTINUING. FOR THIS AFTERNOON...THE DEEP MOISTURE WILL CONTINUE TO BE SHUNTED TO THE SOUTH OF THE REGION...WITH SOME LINGERING LOW LEVEL MOISTURE AROUND IN THE EVENING. BY LATE EVENING...SKIES SHOULD CLEAR ACROSS MUCH OF THE AREA. WHILE THIS COULD POTENTIALLY PROMOTE FOG DEVELOPMENT...SOUTHWESTERLY SURFACE WINDS DEVELOP BY MIDNIGHT...WHICH WOULD SCOUR OUT THE FOG POTENTIAL RATHER FAST. WILL LET LATER FORECASTS RE-EVALUATE THIS FOG POTENTIAL. ALSO...LOW TEMPS TONIGHT ARE TRICKY...AS ENOUGH CLEARING WITH LIGHT WINDS WOULD SUPPORT SINGLE DIGIT TEMPERATURES...BUT THE SOUTHWEST WINDS WOULD PROVIDE A SUBSTANTIAL MODERATING EFFECT. TEMPS COULD FALL FAST BY LATE EVENING...AND THEN STAY STEADY OR SLOWLY RISE LATER IN THE NIGHT. FOR LOW TEMPS TONIGHT...I WENT WITH A COMPROMISE...GOING UNDER GUIDANCE A BIT...WITH LOW TEMPS TONIGHT IN THE TEENS ACROSS MUCH OF THE AREA. AS FOR FOG THIS MORNING...THE SOUTHWEST TWO THIRDS OF THE CWA COULD EXPERIENCE PATCHY FOG THROUGH EARLY MORNING.. THEN ON TUESDAY...A POSITIVELY TILTED UPPER LEVEL RIDGE WILL BUILD INTO THE REGION...WITH LARGE SCALE SUBSIDENCE PROMOTING PARTLY TO MOSTLY SUNNY SKIES. THEN BY TUESDAY NIGHT AND WEDNESDAY...A FAST MOVING...WEAK SHORTWAVE TROUGH WILL TRAVERSE ACROSS THE REGION IN MOIST WEST-NORTHWESTERLY FLOW ALOFT...WHICH WILL COMBINE WITH INCREASING DEEP MOISTURE TO PRODUCE SNOW OVER THE WESTERN MOUNTAINS. SOME PRECIP IN THE FORM OF A RAIN/SNOW MIX COULD GET GOING OVER THE PLAINS ON WEDNESDAY. STRONG WINDS WILL BE POSSIBLE OVER THE ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS ON WEDNESDAY. OTHERWISE...TEMPERATURES ON TUESDAY AND WEDNESDAY WILL BE ABOVE SEASONAL AVERAGES ACROSS THE FORECAST AREA WITH THE RIDGE BUILDING IN...ALONG WITH LEE TROUGHING IN CENTRAL/EASTERN MONTANA SUPPORTING DOWNSLOPE LOW LEVEL FLOW. COHEN WEDNESDAY NIGHT THROUGH THURSDAY...A WEAK UPPER LEVEL RIDGE OF HIGH PRESSURE WILL COLLAPSE OVER MONTANA DURING THIS PERIOD...AS AN UPPER LEVEL DISTURBANCE MOVES SOUTHWARD OUT OF ALBERTA TOWARDS CENTRAL MONTANA. EXPECT WINDY CONDITIONS OVER NORTH CENTRAL MONTANA WEDNESDAY NIGHT INTO THURSDAY MORNING...WHILE THE CHANCES FOR SNOW WILL INCREASE DURING THE NIGHT OVER THE NORTHERN SECTIONS OF NORTH CENTRAL MONTANA. BY THURSDAY...WITH THE UPPER LEVEL DISTURBANCE MOVING THROUGH...THERE WILL BE A GOOD CHANCE FOR SNOW ACROSS PORTIONS OF THE REGION...THUS POPS HAVE BEEN INCREASED A BIT FOR THURSDAY FROM CUT BANK...TO GREAT FALLS...TO LEWISTOWN. FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT...EXPECT A QUICK TRANSITION FROM COOL AIR TO VERY MILD AIR...AS A WARM FRONT MOVES THROUGH THE REGION ON THURSDAY NIGHT. AFTER THE WARM FRONT MOVES THROUGH...EXPECT VERY WINDY CONDITIONS TO DEVELOP ON FRIDAY...HELPING TO USHER IN THE WARMER AIR. RIGHT NOW...WIND SPEEDS SHOULD REMAIN BELOW WARNING CRITERIA...BUT THIS WILL NEED TO BE WATCHED CLOSELY OVER THE NEXT FEW DAYS. AFTERNOON TEMPERATURES ON FRIDAY WILL AVERAGE BETWEEN 10 AND 15 DEGREES ABOVE NORMAL ACROSS THE REGION. FOR SATURDAY AND SATURDAY NIGHT...THE GFS/ECMWF BOTH SHOW ANOTHER CANADIAN COLD FRONT MOVING SOUTHWARD THROUGH THE REGION. EXPECT ANOTHER QUICK CHANGE IN TEMPERATURES...WITH TEMPERATURES TURNING COLDER AND FALLING BACK BELOW NORMAL. ADDITIONALLY...EXPECT ANOTHER ROUND OF RAIN/SNOW ACROSS CENTRAL AND SOUTHWEST MONTANA AS THE COLD FRONT MOVES THROUGH. BRUSDA SUNDAY AND MONDAY...MODELS CONTINUE TO BRING A PACIFIC DISTURBANCE THROUGH THE REGION. A CHANCE FOR SCATTERED SNOW SHOWERS IN THE MOUNTAINS AND A SLIGHT CHANCE ON THE PLAINS. TEMPERATURES ARE EXPECTED TO BE NEAR NORMAL THROUGH THIS PERIOD. SAUCIER && .PRELIMINARY POINT TEMPS/POPS... GTF 32 19 46 27 / 100 0 0 0 CTB 31 16 44 24 / 40 0 0 10 HLN 33 20 44 23 / 100 20 10 0 BZN 35 13 42 16 / 100 40 10 0 WEY 29 4 30 8 / 100 50 10 10 DLN 32 16 40 21 / 100 40 0 0 HVR 30 13 42 20 / 20 0 0 0 LWT 31 18 42 22 / 100 10 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... SNOW ADVISORY UNTIL NOON MST TODAY FOR MTZ012>014-048>051-054. && $$ mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 912 AM MST MON FEB 25 2008 .UPDATE... TODAY...THE LARGE SCALE PATTERN HAS AN UPPER LEVEL HIGH PRESSURE RIDGE BUILDING OVER THE WEST COAST WHILE A BROAD LOW PRESSURE TROF MOVES EAST INTO THE MIDWEST. THIS LEAVES THE ZONES BENEATH NORTHWEST FLOW ALOFT. THE MAIN INTEREST FOR TODAY IS A VORT MAX MOVING THROUGH THIS FLOW...ACROSS NORTHWEST MONTANA INTO THE SOUTHWEST ZONES. SOME GOOD LIFT AND MOISTURE WILL ALLOW FOR A GOOD BURST OF SNOW AS THIS FEATURE MOVES SOUTHWARD BUT IT WILL MOVE RAPIDLY AND THE HEAVIEST SNOW SHOULD BE SHORT LIVED. TO THE NORTH...UPSLOPE FLOW IS WEAK AND WILL CONTINUE TO WEAKEN. HAVE DROPPED POPS IN THE NORTH FOR THE REMAINDER OF THIS MORNING AND THIS AFTERNOON. WILL LEAVE THE ADVISORY IN PLACE BUT PLAN ON ALLOWING IT TO EXPIRE AT NOON. ZELZER && .PREV DISCUSSION... /ISSUED 606 AM MST MON FEB 25 2008/ UPDATE... FORECAST PACKAGE AND HAZARDOUS WEATHER OUTLOOK ARE BEING UPDATED TO ACCOUNT FOR HIGHER SNOW AMOUNTS THIS MORNING OVER SOUTHWEST MONTANA...AS SNOW BANDS WORK THEIR WAY SOUTHEASTWARD AHEAD OF A FAST-MOVING...MID-LEVEL SHORTWAVE TROUGH. OVER SOUTHWEST MONTANA FOR THIS MORNING...ADDITIONAL SNOW ACCUMULATIONS OF 1 TO 2 INCHES ARE EXPECTED OVER THE VALLEYS...WITH 2 TO 4 INCHES IN THE MOUNTAINS. COHEN/BRUSDA && .AVIATION... UPDATED 1200Z. A WEAK UPPER LEVEL DISTURBANCE CONTINUES TO MOVE SOUTHEASTWARD THROUGH CENTRAL MONTANA THIS MORNING. EXPECT IFR CONDITIONS WITH AREAS OF LIGHT SNOW AND FOG TO CONTINUE TO AFFECT MUCH OF CENTRAL AND SOUTHWEST MONTANA THROUGH 18Z. SLOWLY IMPROVING CONDITIONS CAN BE EXPECTED FROM 19Z THROUGH 23Z ACROSS THE REGION. MOUNTAINS WILL BE OBSCURED THROUGH MUCH OF THE DAY. AS DRIER AIR MOVES INTO THE REGION AFTER 00Z TUESDAY...EXPECT GRADUALLY CLEARING SKIES AND FOR VFR CONDITIONS TO DEVELOP. HOWEVER...AREAS OF DENSE FOG COULD DEVELOP IF THE AIRMASS COOLS QUICKLY ENOUGH THIS EVENING. SOME LOCATIONS THAT COULD HAVE VLIFR FOG (M1/4SM)...CONDITIONS AFTER 03Z TUESDAY INCLUDE GREAT FALLS...HELENA...BOZEMAN AND CUT BANK...AND THIS WILL BE MONITORED CLOSELY THROUGH THE DAY. THUS DENSE FOG COULD BE ADDED TO THE TAFS IN LATER UPDATES SHOULD THE DENSE FOG LOOK MORE LIKELY TO OCCUR. BRUSDA && .PREV DISCUSSION... /ISSUED 500 AM MST MON FEB 25 2008/ BROAD UPPER LEVEL TROUGH OVER THE CENTRAL CONUS WILL CONTINUE TO PROGRESS EASTWARD TODAY...AS NORTHWESTERLY FLOW ALOFT SETS UP OVER THE REGION. CURRENT IR AND WATER VAPOR SATELLITE IMAGERY INDICATE A RATHER COMPACT MID LEVEL SHORTWAVE TROUGH QUICKLY MOVING SOUTHEASTWARD OVER MONTANA AND IDAHO. MODELS PICK UP ON THIS FEATURE WELL...AND TAKE IT THROUGH THE SOUTHWEST HALF OF MONTANA THIS MORNING. WITH MORE THAN ADEQUATE DEEP MOISTURE ALREADY IN PLACE...LIFT ASSOCIATED WITH THIS SYSTEM WILL PRODUCE AREAS OF SNOW SOUTH OF A CHOTEAU-GREAT FALLS-LEWISTOWN LINE. TO THE NORTH OF THIS LINE...RUC AND OTHER MODELS ARE SHOWING VERY LITTLE...IF ANY...ADDITIONAL SNOWFALL...AS THE BULK OF THE UPPER LEVEL ENERGY RIDES SOUTH OF THOSE AREAS. THUS...THE NORTHERN PORTIONS OF THE SNOW ADVISORY HAVE BEEN CANCELLED...WITH THE REST OF THE SNOW ADVISORY REMAINING IN EFFECT UNTIL NOON MST TODAY. SOUTH OF THE CHOTEAU-GREAT FALLS-LEWISTOWN LINE...UP TO AN INCH OF NEW SNOW WILL BE POSSIBLE OVER THE PLAINS AND VALLEYS...WITH UP TO 2 INCHES OVER THE MOUNTAINS...WITH WEAK UPSLOPE FLOW CONTINUING. FOR THIS AFTERNOON...THE DEEP MOISTURE WILL CONTINUE TO BE SHUNTED TO THE SOUTH OF THE REGION...WITH SOME LINGERING LOW LEVEL MOISTURE AROUND IN THE EVENING. BY LATE EVENING...SKIES SHOULD CLEAR ACROSS MUCH OF THE AREA. WHILE THIS COULD POTENTIALLY PROMOTE FOG DEVELOPMENT...SOUTHWESTERLY SURFACE WINDS DEVELOP BY MIDNIGHT...WHICH WOULD SCOUR OUT THE FOG POTENTIAL RATHER FAST. WILL LET LATER FORECASTS RE-EVALUATE THIS FOG POTENTIAL. ALSO...LOW TEMPS TONIGHT ARE TRICKY...AS ENOUGH CLEARING WITH LIGHT WINDS WOULD SUPPORT SINGLE DIGIT TEMPERATURES...BUT THE SOUTHWEST WINDS WOULD PROVIDE A SUBSTANTIAL MODERATING EFFECT. TEMPS COULD FALL FAST BY LATE EVENING...AND THEN STAY STEADY OR SLOWLY RISE LATER IN THE NIGHT. FOR LOW TEMPS TONIGHT...I WENT WITH A COMPROMISE...GOING UNDER GUIDANCE A BIT...WITH LOW TEMPS TONIGHT IN THE TEENS ACROSS MUCH OF THE AREA. AS FOR FOG THIS MORNING...THE SOUTHWEST TWO THIRDS OF THE CWA COULD EXPERIENCE PATCHY FOG THROUGH EARLY MORNING.. THEN ON TUESDAY...A POSITIVELY TILTED UPPER LEVEL RIDGE WILL BUILD INTO THE REGION...WITH LARGE SCALE SUBSIDENCE PROMOTING PARTLY TO MOSTLY SUNNY SKIES. THEN BY TUESDAY NIGHT AND WEDNESDAY...A FAST MOVING...WEAK SHORTWAVE TROUGH WILL TRAVERSE ACROSS THE REGION IN MOIST WEST-NORTHWESTERLY FLOW ALOFT...WHICH WILL COMBINE WITH INCREASING DEEP MOISTURE TO PRODUCE SNOW OVER THE WESTERN MOUNTAINS. SOME PRECIP IN THE FORM OF A RAIN/SNOW MIX COULD GET GOING OVER THE PLAINS ON WEDNESDAY. STRONG WINDS WILL BE POSSIBLE OVER THE ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS ON WEDNESDAY. OTHERWISE...TEMPERATURES ON TUESDAY AND WEDNESDAY WILL BE ABOVE SEASONAL AVERAGES ACROSS THE FORECAST AREA WITH THE RIDGE BUILDING IN...ALONG WITH LEE TROUGHING IN CENTRAL/EASTERN MONTANA SUPPORTING DOWNSLOPE LOW LEVEL FLOW. COHEN WEDNESDAY NIGHT THROUGH THURSDAY...A WEAK UPPER LEVEL RIDGE OF HIGH PRESSURE WILL COLLAPSE OVER MONTANA DURING THIS PERIOD...AS AN UPPER LEVEL DISTURBANCE MOVES SOUTHWARD OUT OF ALBERTA TOWARDS CENTRAL MONTANA. EXPECT WINDY CONDITIONS OVER NORTH CENTRAL MONTANA WEDNESDAY NIGHT INTO THURSDAY MORNING...WHILE THE CHANCES FOR SNOW WILL INCREASE DURING THE NIGHT OVER THE NORTHERN SECTIONS OF NORTH CENTRAL MONTANA. BY THURSDAY...WITH THE UPPER LEVEL DISTURBANCE MOVING THROUGH...THERE WILL BE A GOOD CHANCE FOR SNOW ACROSS PORTIONS OF THE REGION...THUS POPS HAVE BEEN INCREASED A BIT FOR THURSDAY FROM CUT BANK...TO GREAT FALLS...TO LEWISTOWN. FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT...EXPECT A QUICK TRANSITION FROM COOL AIR TO VERY MILD AIR...AS A WARM FRONT MOVES THROUGH THE REGION ON THURSDAY NIGHT. AFTER THE WARM FRONT MOVES THROUGH...EXPECT VERY WINDY CONDITIONS TO DEVELOP ON FRIDAY...HELPING TO USHER IN THE WARMER AIR. RIGHT NOW...WIND SPEEDS SHOULD REMAIN BELOW WARNING CRITERIA...BUT THIS WILL NEED TO BE WATCHED CLOSELY OVER THE NEXT FEW DAYS. AFTERNOON TEMPERATURES ON FRIDAY WILL AVERAGE BETWEEN 10 AND 15 DEGREES ABOVE NORMAL ACROSS THE REGION. FOR SATURDAY AND SATURDAY NIGHT...THE GFS/ECMWF BOTH SHOW ANOTHER CANADIAN COLD FRONT MOVING SOUTHWARD THROUGH THE REGION. EXPECT ANOTHER QUICK CHANGE IN TEMPERATURES...WITH TEMPERATURES TURNING COLDER AND FALLING BACK BELOW NORMAL. ADDITIONALLY...EXPECT ANOTHER ROUND OF RAIN/SNOW ACROSS CENTRAL AND SOUTHWEST MONTANA AS THE COLD FRONT MOVES THROUGH. BRUSDA SUNDAY AND MONDAY...MODELS CONTINUE TO BRING A PACIFIC DISTURBANCE THROUGH THE REGION. A CHANCE FOR SCATTERED SNOW SHOWERS IN THE MOUNTAINS AND A SLIGHT CHANCE ON THE PLAINS. TEMPERATURES ARE EXPECTED TO BE NEAR NORMAL THROUGH THIS PERIOD. SAUCIER && .PRELIMINARY POINT TEMPS/POPS... GTF 32 19 46 27 / 100 0 0 0 CTB 31 16 44 24 / 40 0 0 10 HLN 33 20 44 23 / 100 20 10 0 BZN 35 13 42 16 / 100 40 10 0 WEY 29 4 30 8 / 100 50 10 10 DLN 32 16 40 21 / 100 40 0 0 HVR 30 13 42 20 / 20 0 0 0 LWT 31 18 42 22 / 100 10 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... SNOW ADVISORY UNTIL NOON MST TODAY FOR MTZ012>014-048>051-054. && $$ mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 606 AM MST MON FEB 25 2008 .UPDATE... FORECAST PACKAGE AND HAZARDOUS WEATHER OUTLOOK ARE BEING UPDATED TO ACCOUNT FOR HIGHER SNOW AMOUNTS THIS MORNING OVER SOUTHWEST MONTANA...AS SNOW BANDS WORK THEIR WAY SOUTHEASTWARD AHEAD OF A FAST-MOVING...MID-LEVEL SHORTWAVE TROUGH. OVER SOUTHWEST MONTANA FOR THIS MORNING...ADDITIONAL SNOW ACCUMULATIONS OF 1 TO 2 INCHES ARE EXPECTED OVER THE VALLEYS...WITH 2 TO 4 INCHES IN THE MOUNTAINS. COHEN/BRUSDA && .AVIATION... UPDATED 1200Z. A WEAK UPPER LEVEL DISTURBANCE CONTINUES TO MOVE SOUTHEASTWARD THROUGH CENTRAL MONTANA THIS MORNING. EXPECT IFR CONDITIONS WITH AREAS OF LIGHT SNOW AND FOG TO CONTINUE TO AFFECT MUCH OF CENTRAL AND SOUTHWEST MONTANA THROUGH 18Z. SLOWLY IMPROVING CONDITIONS CAN BE EXPECTED FROM 19Z THROUGH 23Z ACROSS THE REGION. MOUNTAINS WILL BE OBSCURED THROUGH MUCH OF THE DAY. AS DRIER AIR MOVES INTO THE REGION AFTER 00Z TUESDAY...EXPECT GRADUALLY CLEARING SKIES AND FOR VFR CONDITIONS TO DEVELOP. HOWEVER...AREAS OF DENSE FOG COULD DEVELOP IF THE AIRMASS COOLS QUICKLY ENOUGH THIS EVENING. SOME LOCATIONS THAT COULD HAVE VLIFR FOG (M1/4SM)...CONDITIONS AFTER 03Z TUESDAY INCLUDE GREAT FALLS...HELENA...BOZEMAN AND CUT BANK...AND THIS WILL BE MONITORED CLOSELY THROUGH THE DAY. THUS DENSE FOG COULD BE ADDED TO THE TAFS IN LATER UPDATES SHOULD THE DENSE FOG LOOK MORE LIKELY TO OCCUR. BRUSDA && .PREV DISCUSSION... /ISSUED 500 AM MST MON FEB 25 2008/ BROAD UPPER LEVEL TROUGH OVER THE CENTRAL CONUS WILL CONTINUE TO PROGRESS EASTWARD TODAY...AS NORTHWESTERLY FLOW ALOFT SETS UP OVER THE REGION. CURRENT IR AND WATER VAPOR SATELLITE IMAGERY INDICATE A RATHER COMPACT MID LEVEL SHORTWAVE TROUGH QUICKLY MOVING SOUTHEASTWARD OVER MONTANA AND IDAHO. MODELS PICK UP ON THIS FEATURE WELL...AND TAKE IT THROUGH THE SOUTHWEST HALF OF MONTANA THIS MORNING. WITH MORE THAN ADEQUATE DEEP MOISTURE ALREADY IN PLACE...LIFT ASSOCIATED WITH THIS SYSTEM WILL PRODUCE AREAS OF SNOW SOUTH OF A CHOTEAU-GREAT FALLS-LEWISTOWN LINE. TO THE NORTH OF THIS LINE...RUC AND OTHER MODELS ARE SHOWING VERY LITTLE...IF ANY...ADDITIONAL SNOWFALL...AS THE BULK OF THE UPPER LEVEL ENERGY RIDES SOUTH OF THOSE AREAS. THUS...THE NORTHERN PORTIONS OF THE SNOW ADVISORY HAVE BEEN CANCELLED...WITH THE REST OF THE SNOW ADVISORY REMAINING IN EFFECT UNTIL NOON MST TODAY. SOUTH OF THE CHOTEAU-GREAT FALLS-LEWISTOWN LINE...UP TO AN INCH OF NEW SNOW WILL BE POSSIBLE OVER THE PLAINS AND VALLEYS...WITH UP TO 2 INCHES OVER THE MOUNTAINS...WITH WEAK UPSLOPE FLOW CONTINUING. FOR THIS AFTERNOON...THE DEEP MOISTURE WILL CONTINUE TO BE SHUNTED TO THE SOUTH OF THE REGION...WITH SOME LINGERING LOW LEVEL MOISTURE AROUND IN THE EVENING. BY LATE EVENING...SKIES SHOULD CLEAR ACROSS MUCH OF THE AREA. WHILE THIS COULD POTENTIALLY PROMOTE FOG DEVELOPMENT...SOUTHWESTERLY SURFACE WINDS DEVELOP BY MIDNIGHT...WHICH WOULD SCOUR OUT THE FOG POTENTIAL RATHER FAST. WILL LET LATER FORECASTS RE-EVALUATE THIS FOG POTENTIAL. ALSO...LOW TEMPS TONIGHT ARE TRICKY...AS ENOUGH CLEARING WITH LIGHT WINDS WOULD SUPPORT SINGLE DIGIT TEMPERATURES...BUT THE SOUTHWEST WINDS WOULD PROVIDE A SUBSTANTIAL MODERATING EFFECT. TEMPS COULD FALL FAST BY LATE EVENING...AND THEN STAY STEADY OR SLOWLY RISE LATER IN THE NIGHT. FOR LOW TEMPS TONIGHT...I WENT WITH A COMPROMISE...GOING UNDER GUIDANCE A BIT...WITH LOW TEMPS TONIGHT IN THE TEENS ACROSS MUCH OF THE AREA. AS FOR FOG THIS MORNING...THE SOUTHWEST TWO THIRDS OF THE CWA COULD EXPERIENCE PATCHY FOG THROUGH EARLY MORNING.. THEN ON TUESDAY...A POSITIVELY TILTED UPPER LEVEL RIDGE WILL BUILD INTO THE REGION...WITH LARGE SCALE SUBSIDENCE PROMOTING PARTLY TO MOSTLY SUNNY SKIES. THEN BY TUESDAY NIGHT AND WEDNESDAY...A FAST MOVING...WEAK SHORTWAVE TROUGH WILL TRAVERSE ACROSS THE REGION IN MOIST WEST-NORTHWESTERLY FLOW ALOFT...WHICH WILL COMBINE WITH INCREASING DEEP MOISTURE TO PRODUCE SNOW OVER THE WESTERN MOUNTAINS. SOME PRECIP IN THE FORM OF A RAIN/SNOW MIX COULD GET GOING OVER THE PLAINS ON WEDNESDAY. STRONG WINDS WILL BE POSSIBLE OVER THE ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS ON WEDNESDAY. OTHERWISE...TEMPERATURES ON TUESDAY AND WEDNESDAY WILL BE ABOVE SEASONAL AVERAGES ACROSS THE FORECAST AREA WITH THE RIDGE BUILDING IN...ALONG WITH LEE TROUGHING IN CENTRAL/EASTERN MONTANA SUPPORTING DOWNSLOPE LOW LEVEL FLOW. COHEN WEDNESDAY NIGHT THROUGH THURSDAY...A WEAK UPPER LEVEL RIDGE OF HIGH PRESSURE WILL COLLAPSE OVER MONTANA DURING THIS PERIOD...AS AN UPPER LEVEL DISTURBANCE MOVES SOUTHWARD OUT OF ALBERTA TOWARDS CENTRAL MONTANA. EXPECT WINDY CONDITIONS OVER NORTH CENTRAL MONTANA WEDNESDAY NIGHT INTO THURSDAY MORNING...WHILE THE CHANCES FOR SNOW WILL INCREASE DURING THE NIGHT OVER THE NORTHERN SECTIONS OF NORTH CENTRAL MONTANA. BY THURSDAY...WITH THE UPPER LEVEL DISTURBANCE MOVING THROUGH...THERE WILL BE A GOOD CHANCE FOR SNOW ACROSS PORTIONS OF THE REGION...THUS POPS HAVE BEEN INCREASED A BIT FOR THURSDAY FROM CUT BANK...TO GREAT FALLS...TO LEWISTOWN. FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT...EXPECT A QUICK TRANSITION FROM COOL AIR TO VERY MILD AIR...AS A WARM FRONT MOVES THROUGH THE REGION ON THURSDAY NIGHT. AFTER THE WARM FRONT MOVES THROUGH...EXPECT VERY WINDY CONDITIONS TO DEVELOP ON FRIDAY...HELPING TO USHER IN THE WARMER AIR. RIGHT NOW...WIND SPEEDS SHOULD REMAIN BELOW WARNING CRITERIA...BUT THIS WILL NEED TO BE WATCHED CLOSELY OVER THE NEXT FEW DAYS. AFTERNOON TEMPERATURES ON FRIDAY WILL AVERAGE BETWEEN 10 AND 15 DEGREES ABOVE NORMAL ACROSS THE REGION. FOR SATURDAY AND SATURDAY NIGHT...THE GFS/ECMWF BOTH SHOW ANOTHER CANADIAN COLD FRONT MOVING SOUTHWARD THROUGH THE REGION. EXPECT ANOTHER QUICK CHANGE IN TEMPERATURES...WITH TEMPERATURES TURNING COLDER AND FALLING BACK BELOW NORMAL. ADDITIONALLY...EXPECT ANOTHER ROUND OF RAIN/SNOW ACROSS CENTRAL AND SOUTHWEST MONTANA AS THE COLD FRONT MOVES THROUGH. BRUSDA SUNDAY AND MONDAY...MODELS CONTINUE TO BRING A PACIFIC DISTURBANCE THROUGH THE REGION. A CHANCE FOR SCATTERED SNOW SHOWERS IN THE MOUNTAINS AND A SLIGHT CHANCE ON THE PLAINS. TEMPERATURES ARE EXPECTED TO BE NEAR NORMAL THROUGH THIS PERIOD. SAUCIER && .PRELIMINARY POINT TEMPS/POPS... GTF 32 19 46 27 / 100 0 0 0 CTB 31 16 44 24 / 70 0 0 10 HLN 33 20 44 23 / 100 20 10 0 BZN 35 13 42 16 / 100 40 10 0 WEY 29 4 30 8 / 100 50 10 10 DLN 32 16 40 21 / 100 40 0 0 HVR 30 13 42 20 / 40 0 0 0 LWT 31 18 42 22 / 100 10 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... SNOW ADVISORY UNTIL NOON MST TODAY FOR MTZ012>014-048>051-054. && $$ UPDATE...COHEN/BRUSDA SHORT TERM...COHEN LONG TERM....BRUSDA/SAUCIER AVIATION...BRUSDA mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 500 AM MST MON FEB 25 2008 UPDATED AVIATION SECTION ONLY .DISCUSSION... BROAD UPPER LEVEL TROUGH OVER THE CENTRAL CONUS WILL CONTINUE TO PROGRESS EASTWARD TODAY...AS NORTHWESTERLY FLOW ALOFT SETS UP OVER THE REGION. CURRENT IR AND WATER VAPOR SATELLITE IMAGERY INDICATE A RATHER COMPACT MID LEVEL SHORTWAVE TROUGH QUICKLY MOVING SOUTHEASTWARD OVER MONTANA AND IDAHO. MODELS PICK UP ON THIS FEATURE WELL...AND TAKE IT THROUGH THE SOUTHWEST HALF OF MONTANA THIS MORNING. WITH MORE THAN ADEQUATE DEEP MOISTURE ALREADY IN PLACE...LIFT ASSOCIATED WITH THIS SYSTEM WILL PRODUCE AREAS OF SNOW SOUTH OF A CHOTEAU-GREAT FALLS-LEWISTOWN LINE. TO THE NORTH OF THIS LINE...RUC AND OTHER MODELS ARE SHOWING VERY LITTLE...IF ANY...ADDITIONAL SNOWFALL...AS THE BULK OF THE UPPER LEVEL ENERGY RIDES SOUTH OF THOSE AREAS. THUS...THE NORTHERN PORTIONS OF THE SNOW ADVISORY HAVE BEEN CANCELLED...WITH THE REST OF THE SNOW ADVISORY REMAINING IN EFFECT UNTIL NOON MST TODAY. SOUTH OF THE CHOTEAU-GREAT FALLS-LEWISTOWN LINE...UP TO AN INCH OF NEW SNOW WILL BE POSSIBLE OVER THE PLAINS AND VALLEYS...WITH UP TO 2 INCHES OVER THE MOUNTAINS...WITH WEAK UPSLOPE FLOW CONTINUING. FOR THIS AFTERNOON...THE DEEP MOISTURE WILL CONTINUE TO BE SHUNTED TO THE SOUTH OF THE REGION...WITH SOME LINGERING LOW LEVEL MOISTURE AROUND IN THE EVENING. BY LATE EVENING...SKIES SHOULD CLEAR ACROSS MUCH OF THE AREA. WHILE THIS COULD POTENTIALLY PROMOTE FOG DEVELOPMENT...SOUTHWESTERLY SURFACE WINDS DEVELOP BY MIDNIGHT...WHICH WOULD SCOUR OUT THE FOG POTENTIAL RATHER FAST. WILL LET LATER FORECASTS RE-EVALUATE THIS FOG POTENTIAL. ALSO...LOW TEMPS TONIGHT ARE TRICKY...AS ENOUGH CLEARING WITH LIGHT WINDS WOULD SUPPORT SINGLE DIGIT TEMPERATURES...BUT THE SOUTHWEST WINDS WOULD PROVIDE A SUBSTANTIAL MODERATING EFFECT. TEMPS COULD FALL FAST BY LATE EVENING...AND THEN STAY STEADY OR SLOWLY RISE LATER IN THE NIGHT. FOR LOW TEMPS TONIGHT...I WENT WITH A COMPROMISE...GOING UNDER GUIDANCE A BIT...WITH LOW TEMPS TONIGHT IN THE TEENS ACROSS MUCH OF THE AREA. AS FOR FOG THIS MORNING...THE SOUTHWEST TWO THIRDS OF THE CWA COULD EXPERIENCE PATCHY FOG THROUGH EARLY MORNING.. THEN ON TUESDAY...A POSITIVELY TILTED UPPER LEVEL RIDGE WILL BUILD INTO THE REGION...WITH LARGE SCALE SUBSIDENCE PROMOTING PARTLY TO MOSTLY SUNNY SKIES. THEN BY TUESDAY NIGHT AND WEDNESDAY...A FAST MOVING...WEAK SHORTWAVE TROUGH WILL TRAVERSE ACROSS THE REGION IN MOIST WEST-NORTHWESTERLY FLOW ALOFT...WHICH WILL COMBINE WITH INCREASING DEEP MOISTURE TO PRODUCE SNOW OVER THE WESTERN MOUNTAINS. SOME PRECIP IN THE FORM OF A RAIN/SNOW MIX COULD GET GOING OVER THE PLAINS ON WEDNESDAY. STRONG WINDS WILL BE POSSIBLE OVER THE ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS ON WEDNESDAY. OTHERWISE...TEMPERATURES ON TUESDAY AND WEDNESDAY WILL BE ABOVE SEASONAL AVERAGES ACROSS THE FORECAST AREA WITH THE RIDGE BUILDING IN...ALONG WITH LEE TROUGHING IN CENTRAL/EASTERN MONTANA SUPPORTING DOWNSLOPE LOW LEVEL FLOW. COHEN WEDNESDAY NIGHT THROUGH THURSDAY...A WEAK UPPER LEVEL RIDGE OF HIGH PRESSURE WILL COLLAPSE OVER MONTANA DURING THIS PERIOD...AS AN UPPER LEVEL DISTURBANCE MOVES SOUTHWARD OUT OF ALBERTA TOWARDS CENTRAL MONTANA. EXPECT WINDY CONDITIONS OVER NORTH CENTRAL MONTANA WEDNESDAY NIGHT INTO THURSDAY MORNING...WHILE THE CHANCES FOR SNOW WILL INCREASE DURING THE NIGHT OVER THE NORTHERN SECTIONS OF NORTH CENTRAL MONTANA. BY THURSDAY...WITH THE UPPER LEVEL DISTURBANCE MOVING THROUGH...THERE WILL BE A GOOD CHANCE FOR SNOW ACROSS PORTIONS OF THE REGION...THUS POPS HAVE BEEN INCREASED A BIT FOR THURSDAY FROM CUT BANK...TO GREAT FALLS...TO LEWISTOWN. FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT...EXPECT A QUICK TRANSITION FROM COOL AIR TO VERY MILD AIR...AS A WARM FRONT MOVES THROUGH THE REGION ON THURSDAY NIGHT. AFTER THE WARM FRONT MOVES THROUGH...EXPECT VERY WINDY CONDITIONS TO DEVELOP ON FRIDAY...HELPING TO USHER IN THE WARMER AIR. RIGHT NOW...WIND SPEEDS SHOULD REMAIN BELOW WARNING CRITERIA...BUT THIS WILL NEED TO BE WATCHED CLOSELY OVER THE NEXT FEW DAYS. AFTERNOON TEMPERATURES ON FRIDAY WILL AVERAGE BETWEEN 10 AND 15 DEGREES ABOVE NORMAL ACROSS THE REGION. FOR SATURDAY AND SATURDAY NIGHT...THE GFS/ECMWF BOTH SHOW ANOTHER CANADIAN COLD FRONT MOVING SOUTHWARD THROUGH THE REGION. EXPECT ANOTHER QUICK CHANGE IN TEMPERATURES...WITH TEMPERATURES TURNING COLDER AND FALLING BACK BELOW NORMAL. ADDITIONALLY...EXPECT ANOTHER ROUND OF RAIN/SNOW ACROSS CENTRAL AND SOUTHWEST MONTANA AS THE COLD FRONT MOVES THROUGH. BRUSDA SUNDAY AND MONDAY...MODELS CONTINUE TO BRING A PACIFIC DISTURBANCE THROUGH THE REGION. A CHANCE FOR SCATTERED SNOW SHOWERS IN THE MOUNTAINS AND A SLIGHT CHANCE ON THE PLAINS. TEMPERATURES ARE EXPECTED TO BE NEAR NORMAL THROUGH THIS PERIOD. SAUCIER && .AVIATION... UPDATED 1200Z. A WEAK UPPER LEVEL DISTURBANCE CONTINUES TO MOVE SOUTHEASTWARD THROUGH CENTRAL MONTANA THIS MORNING. EXPECT IFR CONDITIONS WITH AREAS OF LIGHT SNOW AND FOG TO CONTINUE TO AFFECT MUCH OF CENTRAL AND SOUTHWEST MONTANA THROUGH 18Z. SLOWLY IMPROVING CONDITIONS CAN BE EXPECTED FROM 19Z THROUGH 23Z ACROSS THE REGION. MOUNTAINS WILL BE OBSCURED THROUGH MUCH OF THE DAY. AS DRIER AIR MOVES INTO THE REGION AFTER 00Z TUESDAY...EXPECT GRADUALLY CLEARING SKIES AND FOR VFR CONDITIONS TO DEVELOP. HOWEVER...AREAS OF DENSE FOG COULD DEVELOP IF THE AIRMASS COOLS QUICKLY ENOUGH THIS EVENING. SOME LOCATIONS THAT COULD HAVE VLIFR FOG (M1/4SM)...CONDITIONS AFTER 03Z TUESDAY INCLUDE GREAT FALLS...HELENA...BOZEMAN AND CUT BANK...AND THIS WILL BE MONITORED CLOSELY THROUGH THE DAY. THUS DENSE FOG COULD BE ADDED TO THE TAFS IN LATER UPDATES SHOULD THE DENSE FOG LOOK MORE LIKELY TO OCCUR. BRUSDA && .PRELIMINARY POINT TEMPS/POPS... GTF 32 19 46 27 / 100 0 0 0 CTB 31 16 44 24 / 70 0 0 10 HLN 33 20 44 23 / 80 20 10 0 BZN 35 13 42 16 / 90 40 10 0 WEY 29 4 30 8 / 90 50 10 10 DLN 32 16 40 21 / 90 40 0 0 HVR 30 13 42 20 / 40 0 0 0 LWT 31 18 42 22 / 100 10 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... SNOW ADVISORY UNTIL NOON MST TODAY FOR MTZ012>014-048>051-054. && $$ SHORT TERM...COHEN LONG TERM....BRUSDA/SAUCIER AVIATION...BRUSDA mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREAT FALLS MT 332 AM MST MON FEB 25 2008 .DISCUSSION... BROAD UPPER LEVEL TROUGH OVER THE CENTRAL CONUS WILL CONTINUE TO PROGRESS EASTWARD TODAY...AS NORTHWESTERLY FLOW ALOFT SETS UP OVER THE REGION. CURRENT IR AND WATER VAPOR SATELLITE IMAGERY INDICATE A RATHER COMPACT MID LEVEL SHORTWAVE TROUGH QUICKLY MOVING SOUTHEASTWARD OVER MONTANA AND IDAHO. MODELS PICK UP ON THIS FEATURE WELL...AND TAKE IT THROUGH THE SOUTHWEST HALF OF MONTANA THIS MORNING. WITH MORE THAN ADEQUATE DEEP MOISTURE ALREADY IN PLACE...LIFT ASSOCIATED WITH THIS SYSTEM WILL PRODUCE AREAS OF SNOW SOUTH OF A CHOTEAU-GREAT FALLS-LEWISTOWN LINE. TO THE NORTH OF THIS LINE...RUC AND OTHER MODELS ARE SHOWING VERY LITTLE...IF ANY...ADDITIONAL SNOWFALL...AS THE BULK OF THE UPPER LEVEL ENERGY RIDES SOUTH OF THOSE AREAS. THUS...THE NORTHERN PORTIONS OF THE SNOW ADVISORY HAVE BEEN CANCELLED...WITH THE REST OF THE SNOW ADVISORY REMAINING IN EFFECT UNTIL NOON MST TODAY. SOUTH OF THE CHOTEAU-GREAT FALLS-LEWISTOWN LINE...UP TO AN INCH OF NEW SNOW WILL BE POSSIBLE OVER THE PLAINS AND VALLEYS...WITH UP TO 2 INCHES OVER THE MOUNTAINS...WITH WEAK UPSLOPE FLOW CONTINUING. FOR THIS AFTERNOON...THE DEEP MOISTURE WILL CONTINUE TO BE SHUNTED TO THE SOUTH OF THE REGION...WITH SOME LINGERING LOW LEVEL MOISTURE AROUND IN THE EVENING. BY LATE EVENING...SKIES SHOULD CLEAR ACROSS MUCH OF THE AREA. WHILE THIS COULD POTENTIALLY PROMOTE FOG DEVELOPMENT...SOUTHWESTERLY SURFACE WINDS DEVELOP BY MIDNIGHT...WHICH WOULD SCOUR OUT THE FOG POTENTIAL RATHER FAST. WILL LET LATER FORECASTS RE-EVALUATE THIS FOG POTENTIAL. ALSO...LOW TEMPS TONIGHT ARE TRICKY...AS ENOUGH CLEARING WITH LIGHT WINDS WOULD SUPPORT SINGLE DIGIT TEMPERATURES...BUT THE SOUTHWEST WINDS WOULD PROVIDE A SUBSTANTIAL MODERATING EFFECT. TEMPS COULD FALL FAST BY LATE EVENING...AND THEN STAY STEADY OR SLOWLY RISE LATER IN THE NIGHT. FOR LOW TEMPS TONIGHT...I WENT WITH A COMPROMISE...GOING UNDER GUIDANCE A BIT...WITH LOW TEMPS TONIGHT IN THE TEENS ACROSS MUCH OF THE AREA. AS FOR FOG THIS MORNING...THE SOUTHWEST TWO THIRDS OF THE CWA COULD EXPERIENCE PATCHY FOG THROUGH EARLY MORNING.. THEN ON TUESDAY...A POSITIVELY TILTED UPPER LEVEL RIDGE WILL BUILD INTO THE REGION...WITH LARGE SCALE SUBSIDENCE PROMOTING PARTLY TO MOSTLY SUNNY SKIES. THEN BY TUESDAY NIGHT AND WEDNESDAY...A FAST MOVING...WEAK SHORTWAVE TROUGH WILL TRAVERSE ACROSS THE REGION IN MOIST WEST-NORTHWESTERLY FLOW ALOFT...WHICH WILL COMBINE WITH INCREASING DEEP MOISTURE TO PRODUCE SNOW OVER THE WESTERN MOUNTAINS. SOME PRECIP IN THE FORM OF A RAIN/SNOW MIX COULD GET GOING OVER THE PLAINS ON WEDNESDAY. STRONG WINDS WILL BE POSSIBLE OVER THE ROCKY MOUNTAIN FRONT AND ADJACENT PLAINS ON WEDNESDAY. OTHERWISE...TEMPERATURES ON TUESDAY AND WEDNESDAY WILL BE ABOVE SEASONAL AVERAGES ACROSS THE FORECAST AREA WITH THE RIDGE BUILDING IN...ALONG WITH LEE TROUGHING IN CENTRAL/EASTERN MONTANA SUPPORTING DOWNSLOPE LOW LEVEL FLOW. COHEN WEDNESDAY NIGHT THROUGH THURSDAY...A WEAK UPPER LEVEL RIDGE OF HIGH PRESSURE WILL COLLAPSE OVER MONTANA DURING THIS PERIOD...AS AN UPPER LEVEL DISTURBANCE MOVES SOUTHWARD OUT OF ALBERTA TOWARDS CENTRAL MONTANA. EXPECT WINDY CONDITIONS OVER NORTH CENTRAL MONTANA WEDNESDAY NIGHT INTO THURSDAY MORNING...WHILE THE CHANCES FOR SNOW WILL INCREASE DURING THE NIGHT OVER THE NORTHERN SECTIONS OF NORTH CENTRAL MONTANA. BY THURSDAY...WITH THE UPPER LEVEL DISTURBANCE MOVING THROUGH...THERE WILL BE A GOOD CHANCE FOR SNOW ACROSS PORTIONS OF THE REGION...THUS POPS HAVE BEEN INCREASED A BIT FOR THURSDAY FROM CUT BANK...TO GREAT FALLS...TO LEWISTOWN. FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT...EXPECT A QUICK TRANSITION FROM COOL AIR TO VERY MILD AIR...AS A WARM FRONT MOVES THROUGH THE REGION ON THURSDAY NIGHT. AFTER THE WARM FRONT MOVES THROUGH...EXPECT VERY WINDY CONDITIONS TO DEVELOP ON FRIDAY...HELPING TO USHER IN THE WARMER AIR. RIGHT NOW...WIND SPEEDS SHOULD REMAIN BELOW WARNING CRITERIA...BUT THIS WILL NEED TO BE WATCHED CLOSELY OVER THE NEXT FEW DAYS. AFTERNOON TEMPERATURES ON FRIDAY WILL AVERAGE BETWEEN 10 AND 15 DEGREES ABOVE NORMAL ACROSS THE REGION. FOR SATURDAY AND SATURDAY NIGHT...THE GFS/ECMWF BOTH SHOW ANOTHER CANADIAN COLD FRONT MOVING SOUTHWARD THROUGH THE REGION. EXPECT ANOTHER QUICK CHANGE IN TEMPERATURES...WITH TEMPERATURES TURNING COLDER AND FALLING BACK BELOW NORMAL. ADDITIONALLY...EXPECT ANOTHER ROUND OF RAIN/SNOW ACROSS CENTRAL AND SOUTHWEST MONTANA AS THE COLD FRONT MOVES THROUGH. BRUSDA SUNDAY AND MONDAY...MODELS CONTINUE TO BRING A PACIFIC DISTURBANCE THROUGH THE REGION. A CHANCE FOR SCATTERED SNOW SHOWERS IN THE MOUNTAINS AND A SLIGHT CHANCE ON THE PLAINS. TEMPERATURES ARE EXPECTED TO BE NEAR NORMAL THROUGH THIS PERIOD. SAUCIER && .AVIATION... UPDATED 0555Z. THE WEAK UPPER LEVEL SHORTWAVE TROUGH HAS MOVED OUT OF THE AREA THIS EVENING. HOWEVER...THE LINGERING MOIST WESTERLY FLOW ALOFT AND NORTHERLY UPSLOPE SURFACE WINDS WILL CONTINUE THE LIGHT SNOW AND MVFR TO IFR CONDITIONS OVERNIGHT INTO MONDAY MORNING ACROSS NORTH CENTRAL AND CENTRAL MONTANA. SCATTERED SNOW SHOWERS WITH ASSOCIATED MVFR TO LOCAL IFR CONDITIONS WILL ALSO LINGER SOUTHWEST MONTANA OVERNIGHT. ANOTHER SHORTWAVE TROUGH WILL MOVE SOUTHEAST OUT OF BRITISH COLUMBIA AND OVER THE NORTHERN ROCKIES TONIGHT THROUGH MONDAY. THIS SHORTWAVE WILL CAUSE ENHANCED SNOW WITH MORE WIDESPREAD IFR CONDITIONS AT TIMES OVER THE ENTIRE AREA BEGINNING AROUND 09Z IN THE NORTH SPREADING SOUTH OVERNIGHT INTO MONDAY MORNING. THE SNOW WILL DIMINISH AND CONDITIONS WILL IMPROVE IN THE WAKE OF THE SHORTWAVE FROM THE NORTH THROUGHOUT THE DAY. COULSTON && .PRELIMINARY POINT TEMPS/POPS... GTF 32 19 46 27 / 100 0 0 0 CTB 31 16 44 24 / 70 0 0 10 HLN 33 20 44 23 / 80 20 10 0 BZN 35 13 42 16 / 90 40 10 0 WEY 29 4 30 8 / 90 50 10 10 DLN 32 16 40 21 / 90 40 0 0 HVR 30 13 42 20 / 40 0 0 0 LWT 31 18 42 22 / 100 10 0 0 && .TFX WATCHES/WARNINGS/ADVISORIES... SNOW ADVISORY UNTIL NOON MST TODAY FOR MTZ012>014-048>051-054. && $$ SHORT TERM...COHEN LONG TERM....BRUSDA/SAUCIER AVIATION...COULSTON mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 1121 PM CST SAT FEB 23 2008 .AVIATION...06 TAF. AN AREA OF STRATUS CLOUDS IS ADVECTING NORTH FROM KANSAS AND SOUTHERN NEBRASKA ATTM WITH IFR CLOUD HEIGHTS AND THE POTENTIAL FOR IFR VISIBILITIES IN FOG. AS SURFACE WINDS TRANSITION MORE WESTERLY OVERNIGHT THE CLOUD SHIELD WILL SHIFT FARTHER TO THE SOUTH AND EAST WITH VFR CONDITIONS EXPECTED THEREAFTER. && .PREV DISCUSSION... /ISSUED 926 PM CST SAT FEB 23 2008/ UPDATE...UPDATED THE FORECAST PACKAGE FOR THE ENDING OF THE PRECIPITATION AND ADJUSTED THE PATCHY FOG TO AREAS OF FREEZING FOG INSTEAD. AM GAINING CONFIDENCE THAT VISIBILITIES WILL DROP IN AREAS OF FOG/FREEZING FOG TONIGHT INTO SUNDAY MORNING. THE LATEST 00Z NAM/WRF SHOWS THE BOUNDARY LAYER RELATIVE HUMIDITY INCREASING ACROSS MUCH OF THE AREA...WITH THE BEST SATURATION OCCURRING IN THE SOUTH AND EAST. THIS IS ALREADY SHOWING UP ACROSS PORTIONS OF NORTH CENTRAL AND NORTHWEST KANSAS WHERE VISIBILITIES HAVE BEEN DROPPING IN FOG/FREEZING FOG. WILL CONTINUE TO MONITOR TRENDS AND WE MAY NEED A FREEZING FOG TYPE HEADLINE IF VISIBILITIES CONTINUE TO FALL. PREV DISCUSSION... /ISSUED 537 PM CST SAT FEB 23 2008/ UPDATE...SENT A QUICK UPDATE TO THE GRIDS/FORECAST TO INCREASE POPS FOR AN HOUR OR TWO IN THE FAR SOUTH. RAIN/SNOW SHOULD CONTINUE FOR ANOTHER HOUR OR TWO ACROSS NORTH CENTRAL KANSAS...HOWEVER THE LATEST RUC13 SUGGESTS THE STRONGEST LIFT SHUTS DOWN ACROSS THAT AREA QUICKLY BETWEEN 00Z AND 02Z. AFTER CALLING A FEW SPOTS ACROSS NORTH CENTRAL KANSAS IT APPEARS THE RAIN IS CHANGING TO SNOW FROM SOUTH TO NORTH. HUNTER KANSAS PICKED UP A QUICK HALF INCH OF SNOW IN AN HOUR...SO THINK THAT A FEW SPOTS COULD SEE 1 TO 2 INCHES IN THE HEAVIER SNOW BANDS. A LITTLE SLEET IS ALSO NOT OUT OF THE QUESTION...BUT THUS FAR REPORTS HAVE NOT BROUGHT IT INTO OUR CWA YET. PREV DISCUSSION... /ISSUED 326 PM CST SAT FEB 23 2008/ SHORT TERM...THIS EVENING THROUGH MONDAY. NUMEROUS FORECAST CONCERNS WITH THE ONGOING STORM SYSTEM OVER KANSAS AS WELL AS WITH OUR NEXT SYSTEM THAT WILL IMPACT THE AREA SUNDAY NIGHT INTO MONDAY. RADAR CONTINUES TO SHOW BANDS OF PRECIPITATION ACROSS MUCH OF CENTRAL KANSAS INCLUDING OUR KANSAS ZONES. AS OF EARLY THIS AFTERNOON...MOST OF THIS PRECIPITATION WAS FALLING IN THE FORM OF RAIN...BUT THERE WAS SOME SNOW BEGINNING TO MIX IN AT A FEW LOCATIONS. THE PRECIPITATION IS A RESULT OF A WEAK CUT OFF UPPER LEVEL STORM SYSTEM TRACKING ACROSS KANSAS THAT IS SLOWING FILLING AND BECOMING WEAKER WITH TIME. THERE IS A LOT OF WARM AIR AROUND THE AREA THIS AFTERNOON WITH TEMPERATURES IN CENTRAL NEBRASKA AROUND 60 DEGREES. HOWEVER...SFC TEMPERATURES BENEATH THE UPPER LEVEL AREA OF LOW PRESSURE ARE MUCH COOLER DUE TO CLOUD COVER AND PRECIPITATION. CONSEQUENTLY...THERE IS AN UNUSUAL TEMPERATURE CONTRAST OF AROUND 25 DEGREES ACROSS OUR CWA THIS AFTERNOON WITH OUR SOUTHERN KANSAS ZONES ACTUALLY BEING THE COLD SPOT AND ORD IN OUR NORTH BEING THE WARMEST WITH PLENTY OF SUNSHINE. THE UPPER LOW HAS ENOUGH COLD AIR ASSOCIATED WITH IT TO PRODUCE WET SNOW...AND RAIN MAY GRADUALLY MIX WITH AND CHANGE TO SNOW LATE THIS AFTERNOON INTO EARLY THIS EVENING AS THE THERMAL PROFILE SATURATES AND COOLS OVER THE NEXT FEW HOURS. THIS COULD RESULT IN A FEW BURSTS OF SNOW OVER OUR KANSAS ZONES...BUT ACCUMULATIONS SHOULD BE LIGHT AND LESS THAN AN INCH DUE TO SFC TEMPERATURES HOVERING JUST ABOVE FREEZING MAKING IT HARD FOR THE SNOW TO STICK. UPPER SYSTEM CONTINUES TO WEAKEN AND PULL OUT OF THE AREA BY LATE EVENING BRINGING AN END TO THE PRECIPITATION. A WARM UPPER LEVEL RIDGE WILL THEN SPREAD OVER THE AREA ON SUNDAY MAKING FOR A VERY NICE DAY ALL ACROSS OUR CWA. SKIES WILL BE MOSTLY SUNNY WITH SUNDAY AFTERNOON HIGHS CLIMBING INTO THE 50S...WITH WESTERN ZONES POSSIBLY EVEN CLIMBING INTO THE LOWER 60S. THIS WILL BE A SHORT LIVED WARM UP AS A VERY QUICK MOVING STORM SYSTEM TRACKS INTO THE PLAINS ON MONDAY. THIS SYSTEM IS CURRENTLY A VERY IMPRESSIVE LOOKING STORM SYSTEM ON SATELLITE AND IS STILL CHURNING ACROSS THE PACIFIC OCEAN OFF THE COAST OF CALIFORNIA. THE CURRENT ZONAL FLOW PATTERN THAT WE ARE IN WILL QUICKLY TAKE THIS SYSTEM ACROSS THE ROCKIES ON SUNDAY AND INTO THE CENTRAL PLAINS ON MONDAY. THE ROCKIES WILL LIKELY STRIP MUCH OF THE MOISTURE OUT OF THE SYSTEM AND ITS FAST PACE WILL MAKE IT DIFFICULT TO GET MUCH OF A FEED OUT OF THE GULF AFTER EMERGING ONTO THE PLAINS. HOWEVER...IT IS CURRENTLY A STRONG ENOUGH SYSTEM THAT ONE WOULD EXPECT IT TO EMERGE FROM THE ROCKIES AS A STILL FORMIDABLE SYSTEM DESPITE THE BEATING THAT THE ROCKIES PUT ON IT. IN ADDITION...DECENT MOISTURE WITH DEWPOINTS IN THE 40S WILL NOT BE THAT FAR AWAY ACROSS THE OKLAHOMA AREA AND COULD BE AT LEAST PARTIALLY TAPPED INTO. CURRENT MODEL FORECASTS HAVE FOR THE PAST FEW DAYS BEEN PROJECTING A STORM TRACK INTO NORTHERN NEBRASKA NORTH OF INTERSTATE 80 DURING THE DAY ON MONDAY. THE SYSTEM DEEPENS AS IT ENTERS THE PLAINS AND THE QUESTION BECOMES HOW QUICKLY CAN IT DEEPEN. IF IT DEEPENS/STRENGTHENS FAST ENOUGH IT COULD CAUSE NUMEROUS WEATHER RELATED PROBLEMS ACROSS OUR CWA...BUT IF IT IS SLOW TO RESTRENGTHEN THEN LOCATIONS FURTHER EAST LIKE EASTERN NEBRASKA AND IOWA WILL GET THE BRUNT OF THE STORM. GIVEN THAT THIS SYSTEM HAS NOT EVEN COME ASHORE YET...THERE IS STILL UNCERTAINTY WITH THE EXACT STORM TRACK. ONE THING THAT SEEMS MOST CERTAIN IS THAT A COLD FRONT WILL RIP THROUGH THE CWA ON MONDAY WITH STRONG NORTH WINDS OF 20 TO 30 MPH AND FALLING TEMPERATURES AFTER THE FRONT PASSES. THIS COULD CAUSE PROBLEMS WITH BLOWING SNOW AND REDUCED VISIBILITIES IF THE SNOW MATERIALIZES AS SOME FORECAST MODELS INDICATE. THE ECMWF IS CURRENTLY THE COMPUTER MODEL THAT MOST FAVORS ACCUMULATING SNOW FOR PORTIONS OF OUR CWA. PEOPLE WITH TRAVEL PLANS AROUND THE AREA ON MONDAY SHOULD KEEP UP TO DATE WITH THE LATEST FORECAST. LONG TERM...00Z TUESDAY THROUGH SATURDAY. PRIMARY FOCUS IS ON TEMPERATURES WITH PREDOMINANTLY DRY CONDITIONS EXPECTED THROUGH THE PERIOD. LINGERING SNOW OVER THE NORTHEAST HALF OF THE CWA SHOULD BE COMING TO AN END MONDAY EVENING AS ENTIRE SYSTEM CONTINUES TO PULL EAST OF THE REGION. ANY ACCUMULATIONS MONDAY EVENING WILL BE VERY LIGHT...ON THE ORDER OF FLURRIES TO A DUSTING. SUBSIDENCE TAKES HOLD AFTER MIDNIGHT...BRINGING AN END TO ANY LIGHT SNOW. A NORTH TO NORTHWEST FLOW ALOFT THEN PERSISTS INTO TUESDAY IN BETWEEN THE UPPER TROUGH CONTINUING ITS MARCH ACROSS THE EASTERN HALF OF THE COUNTRY AND AN AMPLIFYING RIDGE OVER THE WESTERN CONUS. SURFACE HIGH PRESSURE AND NORTHERLY SURFACE WINDS BENEATH THE NORTH/NORTHWEST FLOW ALOFT ON TUESDAY WILL KEEP TEMPERATURES COOL...WITH HIGHS FORECAST TO RANGE FROM THE LOWER 30S NORTHEAST TO UPPER 30S SOUTHWEST. AN UPPER JET STREAK DIVES DOWN LATE TUESDAY NIGHT INTO EARLY WEDNESDAY...BUT BASED ON PROGGED POSITION OF LEFT EXIT REGION AND ASSOCIATED MID-LEVEL SHORTWAVE ENERGY...BELIEVE ANY CHANCE FOR FLURRIES OR LIGHT SNOW WOULD BE NORTHEAST OF THE CWA WITH JUST SOME MID AND HIGH LEVEL CLOUDS RESULTING FOR NORTHEAST PORTIONS OF THE FORECAST AREA. TEMPERATURES BEGIN TO REBOUND ON WEDNESDAY AS THE SURFACE HIGH SHIFTS EAST AND H85 TEMPS WARM A FEW DEGREES UNDER RISING HEIGHTS ALOFT AS THE WESTERN RIDGE EDGES EASTWARD. WEAK RETURN FLOW AROUND THE SURFACE HIGH STARTS TO DEVELOP LATE DAY WEDNESDAY...CONTINUING WEDNESDAY NIGHT...WHICH WILL HOLD OVERNIGHT TEMPS UP A BIT FROM THE PREVIOUS NIGHT. A CLIPPER SYSTEM MAY BRING A GLANCING SHOT OF SOME LIGHT RAIN OR SNOW TO THE NORTHEAST CWA ON THURSDAY. OVERALL CHANCES LOOK PRETTY LOW AT THIS POINT WITH THE BETTER CHANCES REMAINING NORTHEAST...BUT WILL HANG ONTO THE SLIGHT CHANCE POP IN THE FAR NORTHEAST FOR NOW. THIS CLIPPER WAVE SENDS A WEAK COLD FRONT THROUGH BUT THE TRAILING SURFACE HIGH QUICKLY SLIDES EAST ON FRIDAY WHILE UPPER RIDGING BEGINS TO SLIDE IN FROM THE WEST...SO THAT TEMPERATURES SHOULD RECOVER TO HIGHS CLOSE TO THOSE EXPECTED ON THURSDAY AND MAYBE EVEN WARMER IN THE WEST. THE UPPER RIDGE THEN SPREADS OVER THE CENTRAL PLAINS ON SATURDAY...WHILE A STRONG RETURN FLOW DEVELOPS AT THE SURFACE LEADING TO ABOVE AVERAGE TEMPS. WILL AIM HIGHS IN THE UPPER 40S TO MID 50S FOR NOW. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 255 PM MST MON FEB 25 2008 .DISCUSSION... 21Z SFC ANALYSIS SHOWS A 1023MB HIGH PRES CENTER OVER E AZ AND A 1002MB LOW PRES CENTER OVER N CENTRAL TX. 400-250MB AIRCRAFT WIND PLOT SUPPORTED BY AZTEC AND TUCUMCARI PROFILER DATA SHOWS A 110-140 KNOT JET ACROSS NM WITHIN THE BASE OF A LARGE SCALE TROUGH OVER THE WESTERN UNITED STATES. SFC PRESSURE GRADIENT AND UPPER LEVEL WIND FIELD RESPONSIBLE FOR GUSTY NW WINDS ACROSS THE CWA WITH ADVISORY LEVELS IN THE E PLAINS. RUC13/NAM20 GUIDANCE SHOWS 700MB SPEED MAX OF 30-40 KNOTS OVER THE AREA WILL QUICKLY EJECT EAST INTO W TX THRU LATE THIS AFTERNOON. A FEW SHOWERS AND EVEN A LIGHTNING STRIKE WERE NOTED OVER THE NE HIGHLANDS ON THE LATEST RADAR LOOP. WINDS WILL SUBSIDE QUICKLY AFTER DARK WITH 1034MB HIGH PRES CENTER BUILDING OVER NW NM/SW CO. SHOULD SEE DECENT INVERSIONS IN PLACE OVERNIGHT OVER VALLEY LOCATIONS WITH MIN TEMPS NEAR OR JUST BELOW SEASONAL AVERAGES. SKIES WILL CLEAR IN THE WEST AND REMAIN PARTLY CLOUDY OVER THE EAST AS ANOTHER QUICK HITTING UPPER DISTURBANCE SLIDES SE ACROSS THE NE CORNER OVERNIGHT. LOCATIONS ACROSS NORTHERN CO ARE REPORTING PRECIP AHEAD OF THIS SYSTEM SO LEFT ISOLD POPS OVER THE FAR NE THRU TUESDAY TO REFLECT UNCERTAINTY REGARDING THE AMOUNT OF MOISTURE AND LIFT THAT WILL MOVE IN LATE TONIGHT. A RIDGE THEN BUILDS INTO NM LATE TUESDAY THROUGH FRIDAY WITH TEMPS AROUND 5 TO 10 DEGREES ABOVE NORMAL FOR THE ENTIRE CWA. A TROUGH AXIS MOVES ONSHORE THE WEST COAST WEDNESDAY NIGHT AND SPLITS INTO TWO PIECES OF ENERGY. ONE PIECE MOVES SE INTO THE BAJA AS A DRY CUT OFF LOW AND THE OTHER RACES EAST INTO THE NORTHERN PLAINS STATES FRIDAY. EFFECT ACROSS NM WILL BE A RETURN TO SEASONABLE TEMPS FOR THE WEEKEND. GUYER && .AVIATION... SURFACE FRONT PLOWING DOWN EASTERN PLAINS...VCNTY KLVS-KLBB LINE AT 21Z. THIS BOUNDARY WILL CONTINUE MOVING SOUTHWARD BEFORE 01Z. ISOLATED CONVECTION/TSTMS HAVE DEVELOPED BEHIND THE BOUNDARY ACROSS NORTHEAST AND EAST CENTRAL NEW MEXICO...BUT EXPECT THAT ACTIVITY TO DISSIPATE 01-03Z. OTRW...EXPECT NORTHWEST TO NORTH WIND GUSTS OF 25 TO 40 KTS PRODUCING ISOLD VSBY OBSCURATIONS IN BLDU TO DIMINISH BY 06Z. NEXT AVIATION DISCUSSION SCHEDULED FOR 10Z. && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 26 51 24 54 / 0 0 0 0 GALLUP.......................... 18 50 18 58 / 0 0 0 0 GRANTS.......................... 18 51 18 57 / 0 0 0 0 GLENWOOD........................ 29 66 28 70 / 0 0 0 0 CHAMA........................... 12 42 12 45 / 10 0 0 0 LOS ALAMOS...................... 22 46 24 50 / 0 0 0 0 RED RIVER....................... 12 37 10 41 / 10 5 0 0 TAOS............................ 14 45 13 50 / 0 0 0 0 SANTA FE........................ 24 49 24 54 / 0 0 0 0 SANTA FE AIRPORT................ 23 48 23 56 / 0 0 0 0 ESPANOLA........................ 20 48 19 59 / 0 0 0 0 ALBUQUERQUE HEIGHTS............. 30 55 32 60 / 0 0 0 0 ALBUQUERQUE VALLEY.............. 26 54 28 61 / 0 0 0 0 ALBUQUERQUE FOOTHILLS........... 30 56 29 60 / 0 0 0 0 ALBUQUERQUE WEST MESA........... 27 56 29 60 / 0 0 0 0 SOCORRO......................... 29 60 28 65 / 0 0 0 0 SANDIA PARK/CEDAR CREST......... 20 45 20 56 / 0 0 0 0 MORIARTY/ESTANCIA............... 24 51 20 58 / 0 0 0 0 CARRIZOZO....................... 27 58 30 62 / 0 0 0 0 RUIDOSO......................... 25 52 27 58 / 0 0 0 0 RATON........................... 19 47 15 57 / 5 10 0 0 LAS VEGAS....................... 18 45 21 56 / 5 10 0 0 ROY............................. 23 47 25 58 / 5 10 0 0 CLAYTON......................... 25 49 28 60 / 5 10 0 0 SANTA ROSA...................... 30 55 28 67 / 0 5 0 0 TUCUMCARI....................... 29 54 27 66 / 0 10 0 0 FORT SUMNER..................... 30 57 29 67 / 0 5 0 0 CLOVIS.......................... 30 52 30 64 / 0 0 0 0 PORTALES........................ 29 53 29 66 / 0 0 0 0 ROSWELL......................... 35 59 30 71 / 0 0 0 0 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ GUYER/99 nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 711 PM EST MON FEB 25 2008 .SYNOPSIS... AN AREA OF HIGH PRESSURE ALONG THE EASTERN SEABOARD WILL RETREAT OFF THE EAST COAST TONIGHT. MEANWHILE AN AREA OF LOW PRESSURE ORGANIZING OVER THE MID SECTION OF THE NATION WILL MOVE EAST THROUGH THE OHIO VALLEY LATE TONIGHT AND TUESDAY AND THEN REACH SOUTHERN NEW ENGLAND TUESDAY NIGHT. THIS LOW WILL SPREAD SNOW INTO THE REGION FROM WEST TO EAST TUESDAY MORNING. PERIODS OF SNOW WILL CONTINUE FROM TUESDAY RIGHT THROUGH WEDNESDAY MORNING...WITH THE PERIOD OF HEAVIEST SNOW EXPECTED TUESDAY NIGHT. THE SNOW MAY MIX WITH A LITTLE SLEET OR RAIN DURING THE DAY TUESDAY NEAR LAKE ERIE AND THE PENNSYLVANIA STATE LINE...BUT OTHERWISE THE PRECIPITATION IS EXPECTED TO BE ALL SNOW. ON WEDNESDAY THE LOW WILL PULL AWAY INTO THE CANADIAN MARITIMES WITH SNOW GRADUALLY DIMINISHING FROM WEST TO EAST. MUCH COLDER AIR WILL FOLLOW THIS SYSTEM WITH TEMPERATURES WELL BELOW AVERAGE FROM WEDNESDAY INTO THURSDAY. SOME LAKE EFFECT SNOW IS ALSO LIKELY SOUTHEAST OF LAKE ONTARIO WEDNESDAY NIGHT INTO THURSDAY. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... ISSUED A QUICK UPDATE TO PUT IN SOME FLURRIES THIS EVENING ACROSS THE EASTERN LAKE ONTARIO REGION BASED ON KTYX RADAR. ALSO BROUGHT IN CHANCE POPS A BIT EARLIER (AFT 06Z) ACROSS THE WESTERN PTNS OF THE SOUTHERN TIER BASED ON LATEST RUC, AND 18Z NAM/GFS. AGREE WITH DISCUSSION BELOW ABT GFS OVEREXTENDING AREAL PRECIP COVERAGE OF .01 QPF LINE BUT 18Z NAM AND THE RUC SUPPORT BRINGING IN CHC POPS TO WESTERN PTNS OF THE SOUTHERN TIER. NO OTHER CHANGES AT THIS TIME. EARLIER DISCUSSION FOLLOWS... THE QUIET WEATHER CONTINUES IN THE NEAR TERM WITH A SURFACE RIDGE OF HIGH PRESSURE CENTERED OVER THE APPALACHIANS. THERE HAS BEEN A GOOD AMOUNT OF SUNSHINE OVER A LARGE MAJORITY OF THE CWA...ESPECIALLY IN THE GENESEE VALLEY AND FINGER LAKES. THE IMMEDIATE BUFFALO AREA HAS BEEN LOCKED UNDER A PLUME OF LAKE EFFECT STRATUS ALL DAY...AND THIS IS NOW BEING REINFORCED WITH A WIDESPREAD AREA OF LOW CLOUDS SPREADING INTO WESTERN NY AT 1930Z. SAME STORY EAST OF LAKE ONTARIO WITH A PLUME OF LOW LAKE EFFECT STRATUS IN PLACE. ALL AREAS WILL BECOME OVERCAST OVERNIGHT AS THE SURFACE RIDGE RETREATS OFF THE EAST COAST AND MOISTURE SPREADS EAST FROM THE DEVELOPING SYSTEM IN THE MIDWEST. THE MAIN CONCERN FOR THE OVERNIGHT WILL BE THE ONSET OF SNOWFALL. UPSTREAM RADAR MOSAIC SHOWING WIDESPREAD RETURNS AS FAR EAST AS NORTHWEST INDIANA...HOWEVER SURFACE OBS SHOW NONE OF THIS REACHING THE GROUND DUE TO A WELL DEFINED DRY LAYER ALOFT. THE GFS IS MUCH FASTER THAN THE NAM AND BRINGS SNOW INTO WESTERN AND NORTHERN NY AFTER ABOUT 09Z. THE GFS OFTEN PLACES TOO LARGE OF A FOOTPRINT ON ITS QPF OWING TO ITS LOWER RESOLUTION...AND SUSPECT THIS IS THE CASE FOR LATER TONIGHT. CANADIAN GEM TIMING IS BETWEEN THE GFS AND NAM...AND THIS SEEMS LIKE A REASONABLE COMPROMISE. WILL REDUCE POPS FROM THE PREVIOUS FORECAST AND JUST GO WITH CHANCE POPS FOR LATE TONIGHT. EXPECT SNOW TO BEGIN AROUND DAYBREAK ACROSS WESTERN NY AND THE SAINT LAWRENCE VALLEY...WHICH IS INTO THE START OF THE 2ND FORECAST PERIOD. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... WILL ISSUE WINTER STORM WARNINGS FOR THE ENTIRE CWA WITH THE AFTERNOON FORECAST PACKAGE FROM TUESDAY MORNING THROUGH WEDNESDAY FOR A LONG DURATION MODERATE INTENSITY SNOW EVENT. MAIN CONCERN THROUGH THE SHORT TERM REVOLVES AROUND ANOTHER SIGNIFICANT SYNOPTIC SYSTEM. MOISTURE CHANNEL IMAGERY SHOWING A WELL DEFINED MID LEVEL CLOSED LOW PULLING EAST THROUGH THE CENTRAL PLAINS. SEVERAL UPPER LEVEL JET STREAKS ARE NOTED ROUNDING THE BASE OF THE MEAN WESTERN CONUS TROUGH...WHICH WILL MOVE ENE AROUND THE SOUTHERN PERIPHERY OF THE MID LEVEL CIRCULATION CENTER AND AID IN DEVELOPING A SIGNIFICANT MID LATITUDE CYCLONE. NAM/GFS STILL AT ODDS WITH RESPECT TO SOME OF THE DETAILS OF THIS SYSTEM... MOST NOTABLY WITH THE TRACK OF THE SURFACE REFLECTION. THE NAM CONTINUES TO BE FARTHER NORTH THAN THE GFS. BELIEVE THIS FARTHER NORTH TRACK HOLDS SOME MERIT...GIVEN THAT THE UPPER AIR OBSERVATIONS AT 12Z SHOW A SLIGHTLY DEEPER/SHARPER TROUGH ACROSS THE CENTRAL CONUS THAN EITHER THE GFS OR NAM INITIALIZATIONS. ALSO...THE TREND THIS ENTIRE WINTER HAS BEEN FOR THESE SYSTEMS TO TRACK FARTHER NORTH THAN FORECAST 24-36 HOURS OUT. GIVEN THIS...FAVOR THE FARTHER NORTH SOLUTION OF THE NAM...ALTHOUGH ITS DETAILS WITH RESPECT TO QPF FIELDS ARE SUSPECT GIVEN THAT IT APPEARS TO BE DOING A POOR JOB OF ATTEMPTING TO RESOLVE SOME MESOSCALE DETAILS. REGARDLESS OF THE EXACT DETAILS...THE LARGE SCALE PATTERN PLACES THE BUFFALO CWA WITHIN THE TARGET ZONE FOR A SIGNIFICANT SNOWFALL WITH THE 700MB CIRCULATION CENTER TRACKING FROM NW PA TO NEAR LAKE CHAMPLAIN. THERE ARE A MULTITUDE OF FORCING MECHANISMS COMING INTO PLAY DURING THE COURSE OF THIS EVENT. FIRST...A SURGE OF WAA/ISENTROPIC UPGLIDE WILL SURGE NORTH IN ADVANCE OF THE SYSTEM. THIS WILL HAVE SOME SUPPORT ALOFT AS WELL WITH AN AREA OF UPPER LEVEL DIVERGENCE IN ASSOCIATION WITH A COUPLED JET STRUCTURE ALOFT. DECENT MOISTURE AVAILABLE DURING THIS FIRST STAGE OF THE EVENT WITH AROUND 3G/KG ON THE 290K ISENTROPIC SURFACE. WITH THE ISENTROPIC UPGLIDE LASTING FOR AN 8-10 HOUR PERIOD...THE GARCIA METHOD WOULD SUGGEST AN AVERAGE OF 3 TO 5 INCHES WITHIN THE WARM AIR ADVECTION PORTION OF THIS STORM. LATE TUESDAY INTO TUESDAY NIGHT THE 700MB CIRCULATION CENTER WILL PASS BY JUST SOUTH OF THE CWA. THERE WILL BE INCREASING DIFFERENTIAL CYCLONIC VORTICITY ADVECTION DURING THIS TIME PERIOD WITH THE APPROACH OF THE UPPER LEVEL WAVE. BOTH THE NAM AND GFS SUGGEST THE DEVELOPMENT OF AN AXIS OF STRETCHING DEFORMATION ALONG THE NORTH AND NORTHWEST PERIPHERY OF THE 700MB LOW...MARKED BY A RIBBON OF ENHANCED 2-D FRONTOGENESIS. NAM-WRF PROFILES ALSO SUGGEST THE POTENTIAL FOR SOME BANDING TUESDAY EVENING...ESPECIALLY CLOSER TO THE NY/PA STATE LINE WHERE THETA-E SURFACES BECOME NEARLY VERTICAL AND SOME LOW LEVEL NEGATIVE EPV BEGINS TO DEVELOP...BOTH SUGGESTING LOW STATIC STABILITY AND THE POTENTIAL FOR SOME EMBEDDED CONVECTIVE ELEMENTS. TEMPERATURE PROFILES ALSO VERY SUPPORTIVE OF ACCUMULATING SNOW WITH A LARGE DENDRITIC CRYSTAL GROWTH ZONE ALOFT AND A DEEP NEARLY SATURATED LAYER BELOW IN THE FAVORED TEMPERATURE RANGE FOR RIMING. GIVEN THE QUALITY OF FORCING AND DEEP MOISTURE...THE BEST PERIOD FOR HEAVIER SNOWFALL APPEARS TO BE FROM LATE TUESDAY AFTERNOON INTO EARLY WEDNESDAY MORNING. THE SYSTEM BEGINS TO PULL AWAY WEDNESDAY...BUT AS COLDER AIR WRAPS INTO THE SYSTEM THE CHANCES FOR LAKE ENHANCEMENT WILL INCREASE ALONG THE SOUTH SHORE OF LAKE ONTARIO. EVEN AS EARLY AS LATE TUESDAY NIGHT ENOUGH COLD AIR ADVECTION BEGINS TO START UP SOME LAKE ENHANCEMENT ON NNE FLOW FROM ROCHESTER TO NIAGARA COUNTY. ON WEDNESDAY BOUNDARY LAYER FLOW WILL GRADUALLY BACK TO THE NNW AND THEN NW WITH LAKE ENHANCEMENT SPREADING EAST TO OSWEGO COUNTY. TEMPERATURE PROFILES REMAIN FAVORABLE FOR GOOD CLOUD MICROPHYSICS THROUGH THE DAY...FURTHER ADDING CREDENCE TO THE POTENTIAL FOR LAKE ENHANCEMENT. THE POTENTIAL FOR LAKE ENHANCEMENT MAY ADD SEVERAL INCHES TO THE SNOWFALL TOTALS ALONG THE SOUTH SHORE OF LAKE ONTARIO. 36 HOUR SNOWFALL TOTALS WILL RANGE FROM AROUND 9 INCHES IN THE BUFFALO METRO AREA...WHICH WILL PROBABLY HAVE THE LOWEST TOTALS IN THIS EVENT...UP TO THE 12-14 INCH RANGE ALONG THE SOUTH SHORE OF LAKE ONTARIO DUE TO LAKE ENHANCEMENT. ALSO HAVE 10-12 INCHES FOR THE SOUTHERN TIER...FINGER LAKES...AND EASTERN LAKE ONTARIO ZONES WHERE THE BEST SYNOPTIC SCALE FORCING IS EXPECTED. AFTER THIS SYSTEM FINALLY PULLS AWAY WEDNESDAY NIGHT...OUR ATTENTION THEN TURNS BACK TO THE MESOSCALE. A NW OR WNW FLOW OF VERY COLD AIR ACROSS THE OPEN LAKE ONTARIO WATERS MAY SET THE STAGE FOR ANOTHER SIGNIFICANT LAKE EFFECT EVENT. BUFKIT ANALYSIS SHOWING A MODERATE COLLIER INDEX AND WELL ALIGNED FLOW. MOST LIKELY TARGET WOULD BE FROM NORTHEAST WAYNE INTO SOUTHERN OSWEGO COUNTIES. GIVEN THE INHERENT UNCERTAINTY AT THIS TIME RANGE HAVE JUST KEPT LIKELY POPS FOR NOW...BUT THIS WILL NEED TO BE WATCHED. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... TWO UPPER SHORT WAVES WILL BRING WEATHER CHANGES THIS PERIOD. THE FIRST WILL BRING A SURFACE LOW ACROSS THE CENTRAL LAKES AND NORTH OF LAKE ONTARIO ON FRIDAY AND ON TO THE ST LAWRENCE VALLEY ON SATURDAY. IT WILL BE FAST MOVING WITH WARM ADVECTION ON FRONT SIDE BRINGING A SLIGHT CHANCE OF MIXED PRECIPITATION...BUT FOR NOW WE KEPT IT ALL SNOW AND 50 POPS. WITH PRELIMINARY ESTIMATES ARE IN THE 1-3 INCH RANGE. A BRIEF PERIOD OF COLDER AIR WILL BUILD IN FRIDAY NIGHT AND SATURDAY IN THE NORTHWEST FLOW ON THE BACK SIDE OF THE LOW, WITH SNOW SHOWERS LINGERING SOUTHEAST OF LAKE ONTARIO. THE NEXT RIDGE BUILDS QUICKLY ACROSS THE REGION SATURDAY NIGHT. A WARMER SOUTHWEST FLOW BEGINS ON SUNDAY WITH 850 MB TEMPS RISING TO NEAR ZERO LATER IN DAY...SO TEMPS SHOULD RISE TO 35 TO 40 MOST AREAS. THE NEXT UPPER TROUGH APPROACHES ON MONDAY A SURFACE LOW AND FRONT AHEAD OF IT, SPREADING MOISTURE IN DURING MONDAY. THE ECMWF IS MUCH WARMER THAN THE GFS, BUT BOTH MODELS SHOW TEMPERATURES WARM ENOUGH FOR A CHANGE TO RAIN AS TEMPERATURES RISE DURING THE DAY. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... A BROAD AREA OF MVFR CEILINGS WILL SPREAD OVER THE WESTERN COUNTIES WEST OF ROCHESTER THIS EVENING...WITH SOME AREAS BREAKING OUT TO UNLIMITED AT TIMES. SNOW WILL MOVE IN FROM THE WEST AND LOWER CEILINGS AND VISIBILITY TO IFR DURING THE MORNING...BUT NOT REACHING WATERTOWN UNTIL MID DAY TUESDAY. IFR CONDITIONS WILL THEN CONTINUE IN SNOW THROUGH TUESDAY NIGHT, LOWERING AT TIMES TO LIFR IN MODERATE SNOW. OUTLOOK... WEDNESDAY...MVFR/IFR IN SNOW SHOWERS ON BACKSIDE OF DEPARTING STORM. THURSDAY...GENERALLY VFR WITH SOME MVFR/IFR RESTRICTION SE OF LAKE ONTARIO IN SNOW SHOWERS. FRIDAY...GENERAL SNOWFALL FOR ENTIRE REGION WITH MVFR/IFR CONDITIONS. SATURDAY AND SUNDAY...GENERALLY VFR CONDITIONS EXCEPT FOR IFR IN SNOW SHOWERS SOUTHEAST OF LAKE ONTARIO ON SATURDAY. && .MARINE... SOUTHWEST WINDS WILL CONTINUE TO WEAKEN TONIGHT AS THEY BACK TO EAST TO NORTHEAST. THE WINDS WILL STRENGTHEN TUESDAY AS LOW PRESSURE MOVES FROM THE OHIO VALLEY ACROSS MARYLAND. SMALL CRAFT ADVISORIES WILL BE LIKELY TUESDAY AFTERNOON. NORTHEAST WINDS WILL BACK TO NORTH AND INCREASE TUESDAY NIGHT WITH GUSTS GALE FORCE TUESDAY NIGHT AND WEDNESDAY AS THE STORM MOVES TO NEW ENGLAND AND DEEPENS. THEY WILL VEER TO NORTHWEST WEDNESDAY NIGHT BUT STILL REMAIN BRISK UNTIL THE NEXT RIDGE APPROACHES THURSDAY. NOTE...SINCE LAKE ERIE IS ALMOST ENTIRELY MOSTLY ICE COVERED...WAVES HAVE BEEN OMITTED FROM THE NEARSHORE FORECAST. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...WINTER STORM WARNING FROM 10 AM TUESDAY TO 4 PM EST WEDNESDAY FOR NYZ004>008. WINTER STORM WARNING FROM 7 AM TUESDAY TO 12 PM EST WEDNESDAY FOR NYZ001>003-010>014-019>021-085. MARINE...NONE. && $$ SYNOPSIS...HITCHCOCK NEAR TERM...HITCHCOCK/JJP SHORT TERM...HITCHCOCK LONG TERM...APB AVIATION...TMA MARINE...APB ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 646 PM EST MON FEB 25 2008 .SYNOPSIS... LOW PRESSURE OVER MISSOURI WILL MOVE UP THE OHIO VALLEY TONIGHT AND REACH SOUTHERN MAINE BY DAYBREAK WEDNESDAY. HIGH PRESSURE WILL TRY TO RETURN TO THE REGION THURSDAY AND FRIDAY. && .NEAR TERM /THROUGH TUESDAY/... THE EVENING HOURS WILL BE QUIET BUT AFTER THAT ALL BETS ARE OFF. MODELS HAVE COME INTO BETTER AGREEMENT AND PRECIP SHOULD ROLL IN FROM THE WEST OVERNIGHT. LOCAL WRF MODEL AND LATEST RUC DON`T HAVE PRECIP MOVING INTO WESTERN ZONES TILL AFT 03Z AND THIS SEEMS REASONABLE. PRECIP WILL BARELY REACH NW PA BY LATE TONIGHT. LOW LEVEL FLOW WILL BE E TO NE OVERNIGHT SO IT APPEARS TEMPS WILL BE COLD ENOUGH FOR MAINLY SNOW OVERNIGHT WITH THE EXCEPTION OF THE FAR SE WHERE FREEZING RAIN MAY TRY TO MIX IN. HAVE LOWERED TEMPS A LITTLE FROM EARLIER FORECAST. HAVE HOISTED WARNINGS FOR ALL BUT FAR SERN ZONES WHICH WILL GET AN ADVISORY. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/... SURFACE LOW SHOULD BE TO THE S OF KCVG AT 12Z AND THEN QUICKLY MOVE NE DURING THE DAY TOMORROW. AREA WILL BE UNDER LEFT FRONT QUAD OF 140 KNOT 300 MB JET TOMORROW MORNING SO PRECIP SHOULD REALLY GET GOING. BEST LOW LEVEL FRONTOGENESIS WILL BE ALONG LINE FROM KMNN TO KMFD TO KYNG DURING THE DAY TOMORROW. EXPECT HEAVIEST PRECIP ALONG THIS AREA. ALTHO MODELS NOW FAIRLY SIMILAR WITH LOW TRACK APPEARS NAM IS BRING TOO MUCH PRECIP N. SO...WILL FOLLOW SOMEWHAT DRIER GFS AND ECMWF SOLUTIONS BUT STILL SHOULD BE ABLE TO MAKE WARNING CRITERIA MOST AREAS. HAVE CONCERN BUT DEPTH OF COLD AIR. DOESN`T APPEAR REALLY COLD AIR ALOFT WILL ARRIVE TILL LATE IN THE DAY SO MAY HAVE A HARD TIME GETTING DENDRITES NEEDED FOR VERY HEAVY SNOW. ALSO WORRY ABOUT LOW LEVEL TEMPS. SE ZONES COULD GET WARM ENOUGH FOR A BRIEF TRANSITION TO FREEZING RAIN OR RAIN THUS HAVE GONE WITH AN ADVISORY AS SNOW TOTALS MAY BE HELD DOWN A BIT. SNOW WILL TRANSITION FROM SYNOPTIC TO LAKE ENHANCED TUESDAY EVENING. WILL END WARNING IN THE WEST AT 03Z WED BUT WILL HANG ON TO IT IN THE EAST. MORE LAKE EFFECT WEDNESDAY INTO WEDNESDAY NIGHT WITH 850 MB TEMPS DIPPING TO NEG 18 DEG. FROZEN LAKE ERIE MAY HOLD DOWN AMOUNTS EXCEPT WHERE LAKE HURON FETCH GETS SET UP. SURFACE RIDGE WILL MOVE THRU ON THURSDAY FINALLY ENDING PRECIP THREAT. BY THAT TIME...NEXT SYSTEM WILL BE KNOCKING ON THE DOOR. GUID TEMPS FOR THE MOST PART LOOK OK. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... COLD FRONT SWEEPS ACROSS THE AREA ON FRIDAY. SNOW SHOWERS POSSIBLE THURSDAY NIGHT AS A WARM FRONT LIFTS NE INTO THE AREA. THEN CHANCE OF SNOW SHOWERS FRIDAY WITH RAIN SHOWERS ALSO POSSIBLE CENTRAL AND SOUTHEAST AREAS WHERE SOMEWHAT WARMER AIR MOVES IN IN ADVANCE OF THE COLD FRONT. WITH THE LOW PASSING NORTH OF THE AREA NOT LOOKING FOR MUCH IN THE WAY OF QPF. CHANCE OF SNOW SHOWERS FRIDAY NIGHT IN THE COLD CYCLONIC FLOW...WITH LIKELY SNOW SHOWERS NE. LINGERING SNOW SHOWERS NE MAINLY IN THE MORNING ON SATURDAY AS HIGH PRESSURE BUILDS IN. FAIR WEATHER SUNDAY WITH HIGH MOVING JUST TO THE EAST. NEXT COLD FRONT WILL MOVE THROUGH ON MONDAY. FOR THE TIMING OF THIS FRONT FOLLOWED CLOSER TO ECMWF MODEL VS. GFS WHICH WHICH WAS ABOUT 12 HOURS FASTER. THIS SHOULD ALLOW THE WARMER AIR TO SPREAD IN AND LOOKING FOR JUST A CHANCE OF SHOWERS ON MONDAY. TEMPERATURES CLOSE TO NORMAL THROUGH THIS PERIOD. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... IT IS ONLY DOWNHILL FROM HERE. MVFR STRATUS AND/OR HAZE HAS PERSISTED ALL DAY AT MOST SITES. FAR NE OHIO/NW PA HAS SCATTERED OUT BOTH AND ARE SITTING VFR...BUT WITH TIME THIS EVENING THEY WILL REJOIN THE REST IN MVFR CEILINGS/VSBY. LOW PRESSURE OVER MISSOURI WILL MOVE EAST TO NORTHERN KENTUCKY BY 12Z TUESDAY. SNOW WILL START SPREADING INTO WESTERN AREAS ABOUT 03Z SPREADING INTO THE EAST BY ABOUT 08Z. MVFR CIGS AND VSBY EXPECTED WHEN SNOW FIRST BEGINS WILL DROP QUICKLY TO IFR OR LOWER WHICH SHOULD THEN LINGER THROUGH THE REST OF THE TAF PERIOD...00Z WEDNESDAY. PRECIP TYPE OTHER THAN SNOW POSSIBLE ACROSS SOUTHERN AREAS INCLUDING CAK/YNG TUE MORNING...BUT BACK TO SNOW TUESDAY AFTERNOON. RIGHT NOW A TRANSITION THROUGH FZRA TO RAIN A POSSIBLE SCENARIO. BEGIN TO PICK UP THE WINDS ON THE BACKSIDE OF THIS SYSTEM LATE IN TUESDAY. STORM TOTAL ACCUMULATIONS OF 6 IN PLUS LIKELY ACROSS MOST AREAS. WHILE IT WILL BE MODERATELY SNOWING DURING THE MORNING HOURS...AREA LOOKS BEST POSITIONED DURING THE AFTERNOON HOURS FOR LIFR SNOW. .OUTLOOK...LOW THEN MOVES ENE TO SOUTHERN NEW ENGLAND TUESDAY NIGHT. WIDESPREAD IFR OR AT BEST LOW MVFR CIGS AND VSBY LIKELY WITH SNOW TRANSITION TO SNOW SHOWERS. WINDS LATER TUE AND TUE NIGHT INCREASING TO AROUND 20 KTS WITH GUSTS OF 35 KNOTS POSSIBLE. ON WEDNESDAY SNOW SHOWERS SHOULD BECOME LESS NUMEROUS THOUGH THEY WILL BE MORE NUMEROUS IN THE NE WHERE TRANSITION TO LAKE EFFECT SNOW SHOWERS WILL TAKE PLACE. VFR LIKELY THURSDAY WITH HIGH PRESSURE MOVING IN. COLD FRONT MOVES THROUGH FRIDAY WITH LOW PRESSURE MOVING SOUTHEAST THROUGH THE GREAT LAKES WITH MVFR/IFR CONDITION POSSIBLE WITH SNOW SHOWERS. HIGH PRESSURE MOVES IN ON SATURDAY FOR IMPROVING CONDITIONS. && .MARINE... MODELS COMING INTO BETTER AGREEMENT MOVING THE DEEPENING LOW SYSTEM NOW OVER THE SOUTHERN PLAINS...ACROSS SOUTHERN OHIO TUESDAY. WINDS INCREASE TO GALE OR NEAR GALE FORCE TUESDAY NIGHT AS ARCTIC AIR MOVES OVER LAKE ERIE. WINDS DROP BELOW GALE FORCE WEDNESDAY. THURSDAY WINDS BECOME LIGHT AND EVENTUALLY TURN SOUTH...AS HIGH PRESSURE MOVES ACROSS THE LAKE. WINDS TURN TO THE WEST LAKE FRIDAY AS ANOTHER COLD FRONT MOVES ACROSS THE LAKE. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...WINTER STORM WARNING FROM 4 AM TUESDAY TO 4 AM EST WEDNESDAY FOR OHZ010>014-020>023-031-089. WINTER WEATHER ADVISORY FROM 4 AM TUESDAY TO 4 AM EST WEDNESDAY FOR OHZ032-033-038. WINTER STORM WARNING FROM 10 PM THIS EVENING TO 10 PM EST TUESDAY FOR OHZ003-006>009-017>019-027>030-036-037-047. PA...WINTER STORM WARNING FROM 4 AM TUESDAY TO 4 AM EST WEDNESDAY FOR PAZ001>003. MARINE...NONE. && $$ SYNOPSIS...KUBINA NEAR TERM...KUBINA SHORT TERM...KUBINA LONG TERM...RANDEL AVIATION...OUDEMAN MARINE...DJB oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON WV 102 PM EST MON FEB 25 2008 .SYNOPSIS... BRIEF BREAK TODAY WITH HIGH PRESSURE. NEXT STRONG FRONT COMES WITH RAIN LATE TONIGHT INTO TUESDAY MORNING...FOLLOWED BY COLDER AIR AND SNOW SHOWERS THROUGH MIDWEEK. ANOTHER COLD FRONT ARRIVES ON FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... MADE A FEW CHANGES WITH THE MORNING UPDATE. KEPT OVC SKIES GOING THROUGH 18Z...AS LOW CLOUDS ARE HANGING TOUGH...WITH LOW LEVEL MOISTURE TRAPPED UNDER INVERSION. MAY BEGIN TO SEE THE CLOUDS LIFT LATE THIS AFTERNOON...ESPECIALLY IN SOUTH. HOWEVER, SKIES SHOULD STILL REMAIN MOSTLY CLOUDY WITH HIGH CLOUDS STREAMING IN FROM WEST...AHEAD OF LOW PRESSURE SYSTEM. ALSO LOWERED MAXT SEVERAL DEGREES IN THE LOWLANDS...WITH LOW CLOUDS KEEPING TEMPS DOWN THIS AFTERNOON. PREVIOUS DISCUSSION BELOW... BIGGEST CHANGE TO FORECAST IN NEAR TERM WAS TO SIGNIFICANTLY INCREASE CLOUD COVER FOR TODAY...BECAUSE OF EXPANSIVE LOW LEVEL STRATUS DECK THAT EXTENDS ACROSS A MUCH LARGER AREA THAN MODELS HAD FORECAST. AS OF 4AM...THESE CLOUDS COVER WESTWARD ALL THE WAY TO THE MISSISSIPPI RIVER...AND NORTHWARD TO CENTRAL OHIO AND NORTHERN INDIANA. THE RUC MODEL HAS DONE THE BEST JOB OF KEEPING UP WITH THE COVERAGE OF THESE CLOUDS...AND USED ITS 900MB RELATIVE HUMIDITY DEPICTION TO FORECAST CLOUDS THROUGH 18Z. WITH WARM AIR ADVECTION ALOFT...AND EVENTUAL SOUTHERLY FLOW LATE TODAY...I STILL FIGURE THAT THERE WILL BE AT LEAST SOME SCATTERING OUT OF LOW CLOUDS FOR A PERIOD THIS AFTERNOON...THOUGH AT THE SAME TIME HIGH CLOUDS WILL BE STREAMING IN AHEAD OF NEXT SYSTEM. FORECAST HIGH TEMPERATURES LEAN STRONGLY ON COOLER MET GUIDANCE...WITH FURTHER ADJUSTING DOWNWARD IN SPOTS. FOR EVOLUTION OF INCOMING SYSTEM...I WENT ALONG WITH HPC PREFERENCE OF GFS VERSUS THE SLOWER NAM. THIS PLACES MAIN FRONTAL RAIN SHOWER BAND ALREADY TO THE MOUNTAINS BY 12Z...WITH A POTENTIAL DRY SLOT ALREADY COMING INTO THE WESTERN ZONES AT THAT TIME. WITH HIGH CONFIDENCE FOR RAIN...I HAVE 80 TO 90 PERCENT POPS AREA-WIDE LATE TONIGHT. TEMPERATURES ARE NON-DIURNAL IN NATURE...WITH RISE TOWARDS MORNING...WHICH WILL KEEP PRECIPITATION TYPE AS ALL RAIN TONIGHT. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... OTHER THAN GOING WITH THE FASTER GFS IN PUSHING COLD FRONT ACROSS THE AREA ON TUESDAY...MODELS ARE CONSISTENT AND PERSISTENT ON THE DEEP UPPER LEVEL TROUGH OVER THE OHIO VALLEY TUESDAY NIGHT THROUGH WEDNESDAY. ALL THE INGREDIENTS ARE THERE FOR AN INCH OR TWO OF SNOW IN THE LOWLANDS TO AT LEAST SEVERAL INCHES IN THE MOUNTAINS TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. WE WILL HAVE A DEEP...COLD...MOIST CYCLONIC FLOW UNDER THE UPPER TROUGH WITH A NORTHWEST OFF THE GREAT LAKES. ALSO...IMPORTANT FOR THIS TIME OF YEAR IN THE LOWLANDS...IS THAT THE BEST CHANCE OF SNOW COMES TUESDAY NIGHT AND WEDNESDAY MORNING WHEN A VORT LOBE ROTATES THROUGH THE UPPER TROUGH. BY WEDNESDAY AFTERNOON...IT WILL MAINLY BE AN UPSLOPE EVENT WITH STILL RATHER DEEP MOISTURE AND A GOOD UPSLOPE COMPONENT TO THE WIND. TEMPS WILL BE WELL BELOW NORMAL. THINGS WIND DOWN WEDNESDAY NIGHT AS THE UPPER TROUGH LIFTS OUT. && .LONG TERM /THURSDAY THROUGH MONDAY/... MODELS SHOW A STRONG UPPER TROUGH DIVING DOWN THROUGH THE GREAT LAKES AND NORTHEAST FRIDAY...BRINGING ANOTHER STRONG COLD FRONT ACROSS BY FRIDAY NIGHT. A WARM FRONT PRECEDES THIS COLD FRONT THURSDAY NIGHT...WITH SNOW SHOWERS CHANGING TO RAIN SHOWERS FRIDAY MORNING AS THE WARM FRONT LIFTS NORTH. FRIDAY WILL LIKELY BE THE MILDEST DAY IN THIS PERIOD AS STRONG SOUTHERLY FLOW PRECEDES THE COLD FRONT. LOOK FOR SCATTERED RAIN SHOWERS WITH THE COLD FRONT...FOLLOWED BY SCATTERED SNOW SHOWERS FRIDAY NIGHT. HIGH PRESSURE WITH DRY AND COOL WEATHER FOR THE WEEKEND AS THIS UPPER TROUGH PAYS ONLY A BRIEF VISIT. GENERAL UPPER TROUGH OVER THE CENTER OF THE NATION WILL DEVELOP BY MONDAY...LEADING A WARMER AND MORE UNSETTLED PATTERN EARLY NEXT WEEK. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... PERSISTENT LOW CLOUDS FROM LOW LEVEL MOISTURE TRAPPED UNDER THE INVERSION HAS KEPT TAF SITES IN MVFR CEILINGS THROUGH MIDDAY...WITH OCCASIONAL IFR. THE LOW CLOUDS WILL BEGIN TO LIFT LATE THIS AFTERNOON AND EVENING...WITH VFR CONDITIONS TONIGHT. A COLD FRONT WILL APPROACH THE AREA TOWARD DAWN TUESDAY. MVFR CEILINGS/OCCASIONAL IFR VISIBILITIES/ IN SHOWERS WITH COLD FRONTAL PASSAGE TOWARD END OF TAF PERIOD. AVIATION OUTLOOK /AFTER 12Z TUESDAY/... IFR CONDITIONS ARE POSSIBLE IN UPSLOPE SNOW SHOWERS TUESDAY NIGHT THROUGH WEDNESDAY NIGHT ESPECIALLY FOR MOUNTAIN TAF SITES. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...MDP/JMV NEAR TERM...MDP/30 SHORT TERM...JMV LONG TERM...JMV AVIATION...30 oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1057 AM CST MON FEB 25 2008 .UPDATE... WIND ADVISORY WAS ADDED TO CENTRAL PARTS OF OKLAHOMA FOR LATER THIS AFTERNOON AND INTO THE EVENING. STRONG COLD ADVECTION IN THE LOWER LAYERS AND PRESENT INDICATIONS IN KANSAS SUPPORT THIS. OVER NORTHWEST OKLAHOMA THE ADVISORY REMAINS UNCHANGED. DEWPOINT TEMPERATURES WERE LOWERED ACCORDING TO OBSERVATIONS IN WEST TEXAS AND RUC FORECASTS FOR AREAS IN THE SOUTHERN PART OF THE RED FLAG WARNING. && .DISCUSSION... && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 66 33 48 27 / 10 10 10 0 HOBART OK 74 34 50 28 / 10 10 10 0 WICHITA FALLS TX 81 36 54 29 / 10 10 10 0 GAGE OK 65 27 50 23 / 10 10 10 0 PONCA CITY OK 65 28 43 23 / 10 10 10 0 DURANT OK 72 38 52 29 / 20 10 10 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 10 PM CST THIS EVENING FOR OKZ013-019-020-023>031-033>040-044. WIND ADVISORY UNTIL 7 PM CST THIS EVENING FOR OKZ004>012-014>018- 021-022. RED FLAG WARNING UNTIL 6 PM CST THIS AFTERNOON FOR OKZ033>038- 044. TX...WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 10 PM CST THIS EVENING FOR TXZ083>086. RED FLAG WARNING UNTIL 6 PM CST THIS AFTERNOON FOR TXZ083>090. && $$ 99/99 ok AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 345 PM CST SUN FEB 24 2008 .DISCUSSION... ST AND FOG CONTS TO DCRS E OF FSD AND CIGS SHUD STILL GO NEXT CPL HRS. SOME REDVLPMNT OF FOG PSBL THIS EVE BUT WITH HIR CLDS FROM APPCHG SYS ALREADY ADVANCNG TWRDS AREA...DO NOT EXPECT IT TO BE MORE THAN A LTL AVIATION PRBLM. OTRW CLDS WILL CONT TO SLWLY INCRS FROM THE W/SW ERY TNGT. NEW NAM12 AND LATEST RUC BOTH CONFIRM DECENT LIFT WITH INCRG MID LVL MOISTURE AND INSTBLTY. WILL TAKE A WHILE FOR PCPN TO DVLP WELL ENUF TO REACH SFC BUT THE PROCESS WILL BE RAPID AND START LATE THIS EVE...WILL KEEP MENTION OF LGT RAIN CHC W OF JAMES RVR LATE EVE FROM 9PM TO MDNGHT. TEMPS WILL COOL STEADILY FOR A WHILE THIS EVE BUT THRU MIDNGT THIS INITIAL CHC OF PCPN SHUD BE WHERE SFC TEMPS REMAIN ABV FRZG. PRECIP SHOULD INCREASE RAPIDLY AFTER 06Z AS MID LEVEL FRONT STRENGTHENS AHEAD OF THE APPROACHING WAVE. BEST DYNAMIC SUPPORT STILL POINTS TO GREATEST PRECIP AMOUNTS THROUGH THE SOUTHERN HALF OF THE FA...GENERALLY SOUTH OF I-90...WITH PRECIP TYPE/TRANSITION TIMING CRITICAL TO NEED FOR HEADLINES. TEMPS ALOFT WARM ENOUGH LATE TONIGHT FOR LIQUID PRECIP THROUGH MOST OF THE FA...WITH A MIX OR CHANGE TO SNOW OCCURRING IN THE FAR NORTH AND FAR WEST VERY LATE IN THE NIGHT. THIS TRANSITION TO SNOW SHOULD CONTINUE TO PROGRESS SOUTHEAST THROUGH THE MORNING...WITH SNOW EXPECTED OVER MOST OF OUR SD/MN COUNTIES BY 15Z WHILE LIQUID PRECIP REMAINS MORE DOMINANT IN NE/IA THROUGH 18Z. GREATEST OVERALL PRECIP AMOUNTS EXPECTED FROM HUTCHINSON AND BON HOMME COUNTIES...EAST THROUGH ALL OF NORTHWEST IOWA...WHERE LIQUID EQUIVALENT VALUES NEAR 0.50 INCH POSSIBLE. TRANSITION TIMING WILL BE KEY TO RESULTANT ICE VS SNOW AMOUNTS. BUT GIVEN CURRENT THINKING...END UP WITH 3-5 INCH SNOW AMOUNTS WITH LESS THAN 0.10 INCH ICE IN FAR SOUTHEAST SD COUNTIES AND DIXON COUNTY NE. WITH LATER TRANSITION TIME IN NORTHWEST IOWA...HAVE ICE AMOUNTS NEARING 0.20 INCH THROUGH MIDDAY MONDAY...TOPPED BY 1-3 INCHES OF SNOW. THEREFORE WILL GO WITH A WINTER WEATHER ADVISORY LATE TONIGHT THROUGH MOST OF MONDAY DUE TO THE MIX OF PRECIP TYPES. ADVISORY WILL BE SOUTH OF I-90 COUNTIES WHERE OVERALL PRECIP AMOUNTS WILL BE LIGHTER...AND NORTH OF SIOUX CITY WHERE POTENTIAL REMAINS FOR WARMER SURFACE TEMPS TO KEEP ICING ISSUES AT BAY. PRECIP SHOULD GRADUALLY EXIT THE AREA FROM NORTHWEST TO SOUTHEAST LATE MONDAY AFTERNOON AND EVENING AS THE WAVE SLIDES EAST OF THE AREA...WITH DRY WEATHER AND SLIGHTLY BELOW NORMAL TEMPS EXPECTED FOR TUESDAY THROUGH WEDNESDAY. PERSISTANT PROGRESSIVE HEMISPHERIC PATTERN TO CONTINUE THROUGH THE EXTENDED PERIOD WITH THE NRN PLAINS UNDER GENERAL WESTERLY FLOW. A COUPLE OF QUICK MOVING WAVES MOVE ACROSS THE AREA DURING THE LATTER HALF OF THE WEEK THROUGH NEXT WEEKEND. FIRST IS WEAKER AND MOVES IN FROM THE WEST-NORTHWEST LATE WEDNESDAY NIGHT AND THURSDAY. THIS LOOKS TO AFFECT MAINLY AREAS NORTHEAST OF OUR FA AT THIS TIME...BUT COULD BRUSH OUR AREA WITH SOME LIGHT PRECIP. SECOND IS A LITTLE STRONGER...CROSSING THE NORTHERN AND CENTRAL ROCKIES SATURDAY NIGHT AND SPREADING SOME PRECIP INTO OUR AREA WITH ELONGATED NORTH-SOUTH TROUGH ON SUNDAY. PRECIP TYPE COULD AGAIN BECOME PROBLEMATIC WITH EACH OF THESE WAVES...AS MILD WESTERLY FLOW BRINGS SHOTS OF WARMER AIR ALOFT INTO THE AREA AHEAD OF EACH WAVE. TEMPERATURES IN GENERAL LOOK TO REMAIN A FEW DEGREES EITHER SIDE OF LATE FEBRUARY/EARLY MARCH NORMALS...WITH EXCEPTION OF SATURDAY/SATURDAY NIGHT WHICH HAS POTENTIAL FOR READINGS 5-10 DEGREES ABOVE NORMAL IN MANY AREAS. && .AVIATION... IFR CIGS AND VSBYS IN ST AND FOG SHUD CONT TO DSIPT REST OF THIS AFTN. MVFR VSBYS IN LGT FOG/HAZE WILL PRBLY PERSIST THRU THE EVE SEVRL AREAS. AFT 06Z CUGS AND VSBYS WILL BEGIN TO LWR IN PCPN FROM THE W WITH CONDS PRBLY QUICKLY GOING TO MVFR AND LCL IFR CIGS/VSBYS 09Z-15Z. AREA OF MORE WDSPRD IFR SHUD DVLP OVER SRN PART OF AREA BY 15Z. AFT 18Z THRU 00Z VSBYS WILL SLWLY IMPRV FROM THE W AS PCPN DCRS WITH CIGS GRDLY GOING BACK TO MVFR FROM THE WDSPRD IFR. WORTH NOTING THAT BESIDES THE FCST OF ANY FZRA IN TAFS...ICING UPSTAIRS IN PCPN WILL CERTAINLY BE A BIG PRBLM AS WELL. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY 3 AM TO 4 PM CST MONDAY FOR SDZ065>071. MN...NONE. IA...WINTER WEATHER ADVISORY 6 AM TO 6 PM CST MONDAY FOR IAZ001>003-012>014-020>022. NE...WINTER WEATHER ADVISORY 3 AM TO 4 PM CST MONDAY FOR NEZ013. && $$ JH/WILLIAMS sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 935 AM EST SUN FEB 24 2008 .DISCUSSION...INTERESTING FORECAST THIS MORNING AS A SHORTWAVE WAS MOVING E-NE FROM THE MID MS VALLEY REGION...AFFECTING PARTS OF THE TN AND OHIO VALLEYS. MOISTURE IS LIMITED WITH 12Z OHX SOUNDING SHOWING VERY DRY AIRMASS BELOW 700 MBS...AND 12Z RNK SOUNDING IS EVEN MORE DRY BELOW 600 MBS. THUS...THESE INITIAL RADAR RETURNS SHOULD CONTINUE TO STRUGGLE TO REACH THE SURFACE FOR THE REST OF THE MORNING...AND THIS IS SUPPORTED BY VIRGA ALL QUADS FROM CHA OBSERVATION. I AM FAIRLY CONFIDENT THAT THE THREAT OF SNOW TODAY... EVEN FOR THE HIGHEST ELEVATIONS OF SWRN VA...IS EXTREMELY MINIMAL. SURFACE TEMPS ARE RUNNING MAINLY IN THE MID TO UPPER 30S AND TEMPS ALOFT GENERALLY 1 TO 6 DEGREES CELSIUS PER LATEST RUC MODEL AND 12Z UPPER AIR PLOTS. I WILL RECONSIDER LIGHT SNOW FOR HIGHEST PARTS OF SWRN VA AND PERHAPS NE TIP OF TN IN THE AFTERNOON PACKAGE. HOWEVER...I HAVE VIEWED 00Z AND 06Z MODEL DATA...AND AM NOT CERTAIN THAT THERE IS ENOUGH INSTABILITY OR LOW LEVEL UPSLOPE FLOW TO SUPPORT SIGNIFICANT SNOWFALL BEFORE THE SHORTWAVE EXITS THE REGION EARLY TONIGHT. FOR NOW...WILL ADJUST FORECAST GRIDS AND WEB PRODUCTS AS NEEDED... BASED ON LATEST RADAR/SATELLITE TRENDS AND HOURLY CONDITIONS. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 51 34 63 46 52 / 20 10 0 60 80 KNOXVILLE AIRPORT, TN 49 33 60 44 54 / 30 10 0 60 70 OAK RIDGE, TN 49 33 60 44 53 / 30 10 0 60 80 TRI CITIES AIRPORT, TN 45 32 56 42 50 / 30 20 0 60 60 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ TG tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 945 PM CST MON FEB 25 2008 .UPDATE... STRONG TO SEVERE THUNDERSTORMS HAVE DEVELOPED ACROSS AREAS EAST OF SMITHVILLE TO GONZALES. WILL INCREASE POPS AND MENTION SEVERE STORMS POSSIBLE FOR FAYETTE AND LAVACA COUNTIES. && .PREV DISCUSSION... /ISSUED 833 PM CST MON FEB 25 2008/ UPDATE... AT 8 PM CDT...COLD FRONT WAS MOVING SOUTHEAST AT 35 MPH AND EXTENDED ALONG A ROCKDALE TO AUSTIN TO BOERNE TO UVALDE TO EAGLE PASS LINE AT 8 PM. SOME SHOWERS WERE NOTED ALONG THE FRONT NORTHEAST OF TAYLOR. THE RUC HAS GENERATED SOME SHOWERS ALONG THE FRONT ACROSS SOUTH CENTRAL TEXAS AND WILL EXPAND SLIGHT CHANCE OF SHOWERS A LITTLE FURTHER TO WEST, THOUGH NOT QUITE TO THE I-35 CORRIDOR. ALSO, TEMPERATURES SHOWED LITTLE DROP OFF BEHIND THE FRONT WITH A DROP OFF NOTED BEHIND A SECOND BOUNDARY ALONG A WACO TO BRADY TO OZONA TO FORT STOCKTON LINE. WILL SLOW TEMPERATURE AND DEWPOINT FALL BASED ON EXPECTED MOVEMENT OF THIS BOUNDARY ACROSS SOUTH CENTRAL TEXAS DURING THE OVERNIGHT HOURS. WIND PROFILES OVER NORTHERN AND WESTERN TEXAS SHOW 45 MPH IN THE LOWER LEVELS. WILL HOLD OFF FOR NOW, HOWEVER LATER SHIFTS MAY HAVE TO ISSUE WIND ADVISORIES FOR ALL OR PART OF SOUTH CENTRAL TEXAS. FIRE WEATHER... RED FLAG WARNING IN EFFECT UNTIL 6 PM CST TUESDAY LOOKS ON TRACK. NOT MUCH RECOVERY OF RELATIVE HUMIDITIES IS EXPECTED OVERNIGHT. PREV DISCUSSION... /ISSUED 526 PM CST MON FEB 25 2008/ AVIATION... DRY SOUTHERLY WINDS GUSTING TO 20 KTS WILL BE REPLACED WITH DRY NORTHERLY WINDS 20 TO 30 KTS BETWEEN 03Z AND 04Z AS A STRONG COLD FRONT PLOWS THROUGH TEXAS. THE BLUSTERY WINDS WILL PERSIST THROUGH 00Z TOMORROW. SKY CONDITIONS WILL REMAIN VFR WITH SCT CIRRUS CLOUDS. PREV DISCUSSION... /ISSUED 324 PM CST MON FEB 25 2008/ DISCUSSION... WINDY...HOT...AND DRY CONDITIONS WILL CONTINUE INTO THE EVENING HOURS AHEAD OF THE COLD FRONT. WINDS WILL SHIFT TO NORTHWEST TO NORTHERLY ACROSS THE ENTIRE REGION BEFORE MIDNIGHT...BUT WILL REMAIN NEAR 20 MPH. THE STRONG NORTHERLY WINDS WILL CONTINUE THROUGH TUESDAY AFTERNOON...WITH GUSTS TO 35 MPH POSSIBLE...BUT SUSTAINED WINDS WILL REMAIN JUST BELOW WIND ADVISORY CRITERIA. A MUCH COOLER AIRMASS WILL FILTER INTO SOUTH CENTRAL TEXAS DURING THE OVERNIGHT HOURS...WITH HIGHS TUESDAY EXPECTED TO BE SOME 20 DEGREES BELOW MONDAY`S. CLEAR SKIES OVERNIGHT AND DECREASING WINDS WILL PROMOTE GOOD RADIATIONAL COOLING LEADING TO TEMPERATURES BELOW FREEZING ACROSS THE HILL COUNTRY...AND NEAR FREEZING ACROSS THE REST OF THE AREA. WINDS WILL BEGIN TO SHIFT BACK TO THE SOUTHEAST ON WEDNESDAY ALLOWING SHALLOW GULF MOISTURE TO RETURN. THIS INCREASE IN MOISTURE SHOULD BE EVIDENT EARLY THURSDAY MORNING WITH PATCHY FOG DEVELOPMENT EXPECTED IN THE NEAR-SUNRISE HOURS MAINLY ALONG AND SOUTHEAST OF THE I-35 CORRIDOR. NEARLY ZONAL FLOW ALOFT WILL ENABLE A MODEST WARMING TREND THROUGH THE END OF THE WORK WEEK AND INTO THE WEEKEND. THE NEXT BEST CHANCE FOR RAIN APPEARS TO BE LATE FRIDAY INTO SATURDAY. LOW LEVEL MOISTURE WILL HAVE HAD MORE TIME TO DEEPEN AND A TROUGH PASSING WELL TO THE NORTH MAY PROVIDE ENOUGH INSTABILITY FOR SOME CONVECTIVE ACTIVITY. ATTM...LOW-END CHC POPS SEEM REASONABLE. MODELS ARE STILL INDICATING A POLAR COLD FRONT ARRIVING LATE IN THE WEEKEND TO EARLY NEXT WEEK. FIRE WEATHER... STRONG SOUTHWEST WINDS WILL CONTINUE INTO THE EVENING HOURS AHEAD OF A STRONG COLD FRONT. THE FRONT WILL MOVE INTO SOUTH CENTRAL TEXAS THIS EVENING AND OVERNIGHT AND BRING EVEN DRIER AIR TO THE ENTIRE REGION. GUSTY NORTHWEST WINDS OF 15 TO 25 MPH WILL BEGIN THIS EVENING AND CONTINUE THROUGH MUCH OF TUESDAY. THE WINDS WILL COMBINE WITH RELATIVE HUMIDITY VALUES FALLING INTO THE TEENS TO PRODUCE CONDITIONS FAVORABLE FOR THE SPREAD OF FIRE FOR SEVERAL HOURS. && .PRELIMINARY POINT TEMPS/POPS... AUSTIN CAMP MABRY 47 66 37 70 41 / - 0 0 0 0 AUSTIN BERGSTROM INTL AIRPORT 49 62 32 65 33 / - 0 0 0 0 DEL RIO INTL AIRPORT 53 73 38 69 43 / 0 0 0 0 0 SAN ANTONIO INTL AIRPORT 48 69 34 69 38 / - 0 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 6 PM CST TUESDAY FOR THE FOLLOWING COUNTIES: ATASCOSA...BANDERA...BASTROP...BEXAR...BLANCO...BURNET...CALDWELL... COMAL...DE WITT...DIMMIT...EDWARDS...FAYETTE...FRIO...GILLESPIE... GONZALES...GUADALUPE...HAYS...KARNES...KENDALL...KERR...KINNEY... LAVACA...LEE...LLANO...MAVERICK...MEDINA...REAL...TRAVIS...UVALDE... VAL VERDE...WILLIAMSON...WILSON...ZAVALA. && $$ 04/06 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 833 PM CST MON FEB 25 2008 .UPDATE... AT 8 PM CDT...COLD FRONT WAS MOVING SOUTHEAST AT 35 MPH AND EXTENDED ALONG A ROCKDALE TO AUSTIN TO BOERNE TO UVALDE TO EAGLE PASS LINE AT 8 PM. SOME SHOWERS WERE NOTED ALONG THE FRONT NORTHEAST OF TAYLOR. THE RUC HAS GENERATED SOME SHOWERS ALONG THE FRONT ACROSS SOUTH CENTRAL TEXAS AND WILL EXPAND SLIGHT CHANCE OF SHOWERS A LITTLE FURTHER TO WEST, THOUGH NOT QUITE TO THE I-35 CORRIDOR. ALSO, TEMPERATURES SHOWED LITTLE DROP OFF BEHIND THE FRONT WITH A DROP OFF NOTED BEHIND A SECOND BOUNDARY ALONG A WACO TO BRADY TO OZONA TO FORT STOCKTON LINE. WILL SLOW TEMPERATURE AND DEWPOINT FALL BASED ON EXPECTED MOVEMENT OF THIS BOUNDARY ACROSS SOUTH CENTRAL TEXAS DURING THE OVERNIGHT HOURS. WIND PROFILES OVER NORTHERN AND WESTERN TEXAS SHOW 45 MPH IN THE LOWER LEVELS. WILL HOLD OFF FOR NOW, HOWEVER LATER SHIFTS MAY HAVE TO ISSUE WIND ADVISORIES FOR ALL OR PART OF SOUTH CENTRAL TEXAS. && .FIRE WEATHER... RED FLAG WARNING IN EFFECT UNTIL 6 PM CST TUESDAY LOOKS ON TRACK. NOT MUCH RECOVERY OF RELATIVE HUMIDITIES IS EXPECTED OVERNIGHT. && .PREV DISCUSSION... /ISSUED 526 PM CST MON FEB 25 2008/ AVIATION... DRY SOUTHERLY WINDS GUSTING TO 20 KTS WILL BE REPLACED WITH DRY NORTHERLY WINDS 20 TO 30 KTS BETWEEN 03Z AND 04Z AS A STRONG COLD FRONT PLOWS THROUGH TEXAS. THE BLUSTERY WINDS WILL PERSIST THROUGH 00Z TOMORROW. SKY CONDITIONS WILL REMAIN VFR WITH SCT CIRRUS CLOUDS. PREV DISCUSSION... /ISSUED 324 PM CST MON FEB 25 2008/ DISCUSSION... WINDY...HOT...AND DRY CONDITIONS WILL CONTINUE INTO THE EVENING HOURS AHEAD OF THE COLD FRONT. WINDS WILL SHIFT TO NORTHWEST TO NORTHERLY ACROSS THE ENTIRE REGION BEFORE MIDNIGHT...BUT WILL REMAIN NEAR 20 MPH. THE STRONG NORTHERLY WINDS WILL CONTINUE THROUGH TUESDAY AFTERNOON...WITH GUSTS TO 35 MPH POSSIBLE...BUT SUSTAINED WINDS WILL REMAIN JUST BELOW WIND ADVISORY CRITERIA. A MUCH COOLER AIRMASS WILL FILTER INTO SOUTH CENTRAL TEXAS DURING THE OVERNIGHT HOURS...WITH HIGHS TUESDAY EXPECTED TO BE SOME 20 DEGREES BELOW MONDAY`S. CLEAR SKIES OVERNIGHT AND DECREASING WINDS WILL PROMOTE GOOD RADIATIONAL COOLING LEADING TO TEMPERATURES BELOW FREEZING ACROSS THE HILL COUNTRY...AND NEAR FREEZING ACROSS THE REST OF THE AREA. WINDS WILL BEGIN TO SHIFT BACK TO THE SOUTHEAST ON WEDNESDAY ALLOWING SHALLOW GULF MOISTURE TO RETURN. THIS INCREASE IN MOISTURE SHOULD BE EVIDENT EARLY THURSDAY MORNING WITH PATCHY FOG DEVELOPMENT EXPECTED IN THE NEAR-SUNRISE HOURS MAINLY ALONG AND SOUTHEAST OF THE I-35 CORRIDOR. NEARLY ZONAL FLOW ALOFT WILL ENABLE A MODEST WARMING TREND THROUGH THE END OF THE WORK WEEK AND INTO THE WEEKEND. THE NEXT BEST CHANCE FOR RAIN APPEARS TO BE LATE FRIDAY INTO SATURDAY. LOW LEVEL MOISTURE WILL HAVE HAD MORE TIME TO DEEPEN AND A TROUGH PASSING WELL TO THE NORTH MAY PROVIDE ENOUGH INSTABILITY FOR SOME CONVECTIVE ACTIVITY. ATTM...LOW-END CHC POPS SEEM REASONABLE. MODELS ARE STILL INDICATING A POLAR COLD FRONT ARRIVING LATE IN THE WEEKEND TO EARLY NEXT WEEK. FIRE WEATHER... STRONG SOUTHWEST WINDS WILL CONTINUE INTO THE EVENING HOURS AHEAD OF A STRONG COLD FRONT. THE FRONT WILL MOVE INTO SOUTH CENTRAL TEXAS THIS EVENING AND OVERNIGHT AND BRING EVEN DRIER AIR TO THE ENTIRE REGION. GUSTY NORTHWEST WINDS OF 15 TO 25 MPH WILL BEGIN THIS EVENING AND CONTINUE THROUGH MUCH OF TUESDAY. THE WINDS WILL COMBINE WITH RELATIVE HUMIDITY VALUES FALLING INTO THE TEENS TO PRODUCE CONDITIONS FAVORABLE FOR THE SPREAD OF FIRE FOR SEVERAL HOURS. && .PRELIMINARY POINT TEMPS/POPS... AUSTIN CAMP MABRY 92 47 66 37 70 / 0 - 0 0 0 AUSTIN BERGSTROM INTL AIRPORT 89 49 62 32 65 / 0 - 0 0 0 DEL RIO INTL AIRPORT 99 53 73 38 69 / 0 0 0 0 0 SAN ANTONIO INTL AIRPORT 92 48 69 34 69 / 0 - 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 6 PM CST TUESDAY FOR THE FOLLOWING COUNTIES: ATASCOSA...BANDERA...BASTROP...BEXAR...BLANCO...BURNET...CALDWELL... COMAL...DE WITT...DIMMIT...EDWARDS...FAYETTE...FRIO...GILLESPIE... GONZALES...GUADALUPE...HAYS...KARNES...KENDALL...KERR...KINNEY... LAVACA...LEE...LLANO...MAVERICK...MEDINA...REAL...TRAVIS...UVALDE... VAL VERDE...WILLIAMSON...WILSON...ZAVALA. && $$ 04/06 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 943 AM CST MON FEB 25 2008 .DISCUSSION... POST-10Z DENSE FOG DECK THAT QUICKLY EXPANDED INLAND FROM THE SOUTHWEST IS STILL AN ISSUE AT 1530Z. THERE IS A DENSE FOG ADVISORY FOR THE CWA`S SOUTHERN 1/3RD (INCLUDING GALVESTON BAY) THROUGH NOON. VISIBILITIES OF 1/4 MILE OR UNDER OCCURRING OVER GALVESTON BAY AND SURROUNDING COMMUNITIES WILL LINGER WELL ON THROUGH NOON AS THE SUN EATS AWAY FROM THE NORTHERN FRINGES OF THE DECK. HIGHER SW BREEZES TOWARDS THE MATAGORDA BAY REGION HAVE ALREADY MIXED OUT DENSE FOG...THOUGH FEEL THE GALVESTON BAY AREA WILL BE THE LAST TO SEE THE SUNSHINE. AFTER INSPECTING THE LOCAL AREA SOUNDINGS AND MOS NUMBERS...THEY ALL SUPPORT AFTERNOON MAXIMUMS IN THE LOW TO MIDDLE 80S. THE HIGH PROBABILITY OF LIGHT FOG...OR HAZE...DOES EXIST ACROSS THE SOUTHERN 1/3 COASTAL COUNTIES AND OVER GALVESTON BAY THE ENTIRE DAY. TONIGHT`S FROPA IS SCHEDULED TO MAKE IT ACROSS THE CWA FROM TUESDAY 06-12Z WHICH WILL BE MUCH MORE OF A FOG DISPERSER THAN A RAIN MAKER. 31 && .PREV DISCUSSION... /ISSUED 353 AM CST MON FEB 25 2008/ DISCUSSION... SFC ANALYSIS SHOWS A NEARLY STATIONARY FRONT ACROSS THE NORTHERN PORTIONS OF THE COASTAL COUNTIES THIS HOUR. SFC DEWPOINTS HAVE INCREASED TO AROUND 60 SOUTH OF THE BOUNDARY WHERE WIDESPREAD DENSE FOG HAS ADVECTED INLAND. DRIER AIRMASS HAS PRECLUDED FOG DEVELOPMENT NORTH OF THE FRONT. APPEARS THAT THE FOG COULD ADVECT AS FAR INLAND AS THE I-10 CORRIDOR. FOR NOW HAVE REMOVED THE ADVISORY FOR THE NRN COUNTIES. WILL ASSESS IT AGAIN IN A COUPLE OF HOURS AND MAYBE TRIM A FEW MORE COUNTIES. VISIBILITIES SHOULD QUICKLY IMPROVE OVER LAND AREAS BY 14-15Z AS THE SFC WINDS INCREASE...BUT MAY TAKE A BIT LONGER TO RECOVER OVER THE WATERS. FOG COULD DEVELOP AGAIN OVER THE BAYS/WATERS FOR A FEW HOURS THIS EVENING BEFORE THE FRONT CROSSES. COLD FRONT ACROSS THE ROCKIES/NRN PLAINS WILL DROP QUICKLY SOUTH REACHING THE RED RIVER VALLEY LATE THIS AFTN. LOW LEVEL SOUTHWEST FLOW WILL ALLOW TEMPS TO WARM TO 18-20C AT THE 850 MB LEVEL. WITH LOTS OF SUN...TEMPS SHOULD EASILY REACH THE 80S MOST INLAND AREAS. THE FRONT WILL CROSS SE TX 02-08Z TONIGHT...AND SHOULD CLEAR THE WATERS BY SUNRISE. GIVEN THE SPARSE MOISTURE AND STRONG CAPPING... LIFT WITH THE FRONT WILL ONLY GENERATE SOME CLOUD COVER AND MAYBE A FEW ISOLATED -SHRA/-TSRA. CLEAR...BREEZY...COOLER CONDITIONS EXPECTED FOR TUESDAY. 1030 MB SFC HIGH SETTLES OVER CWA TUE NIGHT WHICH WILL BE THE COLDEST NIGHT. EXPECTING A LIGHT FREEZE (29-32 DEG) FOR RURAL LOCATIONS OVER OUR NRN HALF. DRY/COOL WEATHER WILL CONTINUE WED/WED NIGHT...THOUGH TEMPS SHOULD NOT BE AS COLD WED NIGHT. ONSHORE FLOW RETURNS THURSDAY RESULTING IN WARMER TEMPS AND AN INCREASE IN LOW LEVEL MOISTURE. LATEST MODEL RUNS HAVE BACKED OFF ON THE STRENGTH OF THE SHORTWAVE PROGGED TO AFFECT THE AREA FRI/SAT. GFS STILL PUSHES A WEAK FRONT INTO THE AREA SATURDAY... AND STILL FORECASTS PWS OF 1.1-1.3 INCHES...SO HAVE OPTED TO KEEP 20/30 POPS GOING. BOTH GFS/ECMWF ARE FORECASTING A VIGOROUS TROUGH TO CARVE OUT OVER TX BEGINNING SUNDAY...WITH AN ASSOCIATED STRONG FROPA ON MONDAY. HAVE MAINTAINED CHANCE POPS FOR THE LATTER PART OF THE WEEKEND. WILL BE INTERESTING TO SEE HOW THE MODELS EVOLVE WITH THIS SYSTEM OVER THE NEXT FEW DAYS. 35 AVIATION... ADVECTION/RADIATION FOG SPREADING ACROSS COASTAL ZONES AFFECTING GLS AND TO A LESSER EXTENT LBX. LOWER DEWPOINTS FROM SGR TO HOU NORTHWARD MAY DELAY FOG DEVELOPMENT UNTIL NEAR DAYBREAK. OBSERVATIONS THE LAST SEVERAL HOURS INDICATE THICK LAYER FOG NEARSHORE AND COASTAL ZONES. TAF SITES FARTHER INLAND SHOULD INITIALLY DEVELOP SHALLOW FOG BUT BECOMING THICKER JUST SHORTLY AFTER DAYBREAK. LATEST RUC PROGGED VERTICAL PROFILES INDICATE FOG LIFTING INTO STRATUS LAYER BY MID MORNING AND SHOULD THIN OUT DISSIPATING BEFORE MID DAY. PRESSURE GRADIENT BECOMING TIGHTER AS DAY PROGRESSES WITH WIND DIRECTION PREVAILING FROM SOUTH BY LATE MORNING TO NOON. 37 MARINE... RELATIVELY LIGHT AND VARIABLE WINDS WILL PICK UP FROM SOUTH TODAY AS PRESSURES START TO FALL RAPIDLY OVER NW TX/OKLAHOMA IN RESPONSE TO PASSING UPPER LEVEL DISTURBANCE. WINDS PICKING UP TO CAUTION LEVELS LATER THIS AFTERNOON FOR COASTAL WATERS AND SCA FOR 20-60 NM REGION TONIGHT. STRONG COLD FRONT ANTICIPATED TO APPROACH COAST AROUND MIDNIGHT AND WINDS SHOULD SIGNIFICANTLY INCREASE BY DAYBREAK TOMORROW TO 20-30 KTS COASTAL WATERS (20-25 KTS BAYS). WAVE HEIGHTS WILL QUICKLY INCREASE THIS AFTERNOON AND TONIGHT AND SHOULD REMAIN ON THE HIGH SIDE THROUGH TOMORROW NIGHT. 37 FIRE WEATHER... MUCH DRIER AIRMASS WILL SPREAD INTO SE TX IN THE WAKE OF TONIGHT`S COLD FRONT. NORTHWEST WINDS OF 15-20 MPH AND RH VALUES OF 25-30 PCT MAY RESULT IN AN ELEVATED FIRE DANGER OVER THE NRN/WRN COUNTIES TUE AFTN. WILL LET NEXT SHIFT ASSESS THE NEED TO ISSUE A FIRE WX WATCH FOR THESE AREAS FOR TUE AFTN. THE LOW RH VALUES WILL PERSIST ON WEDNESDAY BUT WINDS SHOULD REMAIN LIGHT. 35/37 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 84 47 61 33 62 / 0 20 0 0 0 HOUSTON (IAH) 82 52 63 36 61 / 0 20 0 0 0 GALVESTON (GLS) 73 55 64 44 59 / 0 20 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR THE FOLLOWING ZONES: BRAZORIA...CHAMBERS...FORT BEND...GALVESTON...HARRIS... LIBERTY. GM...DENSE FOG ADVISORY UNTIL NOON CST TODAY FOR THE FOLLOWING ZONES: GALVESTON BAY. SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM CST TUESDAY FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT SHOULD EXERCISE CAUTION FROM 3 PM CST THIS AFTERNOON THROUGH THIS EVENING FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 PM CST TUESDAY FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. SMALL CRAFT SHOULD EXERCISE CAUTION FROM 3 PM THIS AFTERNOON TO 8 PM CST THIS EVENING FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM... WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$ DISCUSSION...31 tx AREA FORECAST DISCUSSION...COR TO ADD FIRE WX NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 353 AM CST MON FEB 25 2008 .DISCUSSION... SFC ANALYSIS SHOWS A NEARLY STATIONARY FRONT ACROSS THE NORTHERN PORTIONS OF THE COASTAL COUNTIES THIS HOUR. SFC DEWPOINTS HAVE INCREASED TO AROUND 60 SOUTH OF THE BOUNDARY WHERE WIDESPREAD DENSE FOG HAS ADVECTED INLAND. DRIER AIRMASS HAS PRECLUDED FOG DEVELOPMENT NORTH OF THE FRONT. APPEARS THAT THE FOG COULD ADVECT AS FAR INLAND AS THE I-10 CORRIDOR. FOR NOW HAVE REMOVED THE ADVISORY FOR THE NRN COUNTIES. WILL ASSESS IT AGAIN IN A COUPLE OF HOURS AND MAYBE TRIM A FEW MORE COUNTIES. VISIBILITIES SHOULD QUICKLY IMPROVE OVER LAND AREAS BY 14-15Z AS THE SFC WINDS INCREASE...BUT MAY TAKE A BIT LONGER TO RECOVER OVER THE WATERS. FOG COULD DEVELOP AGAIN OVER THE BAYS/WATERS FOR A FEW HOURS THIS EVENING BEFORE THE FRONT CROSSES. COLD FRONT ACROSS THE ROCKIES/NRN PLAINS WILL DROP QUICKLY SOUTH REACHING THE RED RIVER VALLEY LATE THIS AFTN. LOW LEVEL SOUTHWEST FLOW WILL ALLOW TEMPS TO WARM TO 18-20C AT THE 850 MB LEVEL. WITH LOTS OF SUN...TEMPS SHOULD EASILY REACH THE 80S MOST INLAND AREAS. THE FRONT WILL CROSS SE TX 02-08Z TONIGHT...AND SHOULD CLEAR THE WATERS BY SUNRISE. GIVEN THE SPARSE MOISTURE AND STRONG CAPPING... LIFT WITH THE FRONT WILL ONLY GENERATE SOME CLOUD COVER AND MAYBE A FEW ISOLATED -SHRA/-TSRA. CLEAR...BREEZY...COOLER CONDITIONS EXPECTED FOR TUESDAY. 1030 MB SFC HIGH SETTLES OVER CWA TUE NIGHT WHICH WILL BE THE COLDEST NIGHT. EXPECTING A LIGHT FREEZE (29-32 DEG) FOR RURAL LOCATIONS OVER OUR NRN HALF. DRY/COOL WEATHER WILL CONTINUE WED/WED NIGHT...THOUGH TEMPS SHOULD NOT BE AS COLD WED NIGHT. ONSHORE FLOW RETURNS THURSDAY RESULTING IN WARMER TEMPS AND AN INCREASE IN LOW LEVEL MOISTURE. LATEST MODEL RUNS HAVE BACKED OFF ON THE STRENGTH OF THE SHORTWAVE PROGGED TO AFFECT THE AREA FRI/SAT. GFS STILL PUSHES A WEAK FRONT INTO THE AREA SATURDAY... AND STILL FORECASTS PWS OF 1.1-1.3 INCHES...SO HAVE OPTED TO KEEP 20/30 POPS GOING. BOTH GFS/ECMWF ARE FORECASTING A VIGOROUS TROUGH TO CARVE OUT OVER TX BEGINNING SUNDAY...WITH AN ASSOCIATED STRONG FROPA ON MONDAY. HAVE MAINTAINED CHANCE POPS FOR THE LATTER PART OF THE WEEKEND. WILL BE INTERESTING TO SEE HOW THE MODELS EVOLVE WITH THIS SYSTEM OVER THE NEXT FEW DAYS. 35 && .AVIATION... ADVECTION/RADIATION FOG SPREADING ACROSS COASTAL ZONES AFFECTING GLS AND TO A LESSER EXTENT LBX. LOWER DEWPOINTS FROM SGR TO HOU NORTHWARD MAY DELAY FOG DEVELOPMENT UNTIL NEAR DAYBREAK. OBSERVATIONS THE LAST SEVERAL HOURS INDICATE THICK LAYER FOG NEARSHORE AND COASTAL ZONES. TAF SITES FARTHER INLAND SHOULD INITIALLY DEVELOP SHALLOW FOG BUT BECOMING THICKER JUST SHORTLY AFTER DAYBREAK. LATEST RUC PROGGED VERTICAL PROFILES INDICATE FOG LIFTING INTO STRATUS LAYER BY MID MORNING AND SHOULD THIN OUT DISSIPATING BEFORE MID DAY. PRESSURE GRADIENT BECOMING TIGHTER AS DAY PROGRESSES WITH WIND DIRECTION PREVAILING FROM SOUTH BY LATE MORNING TO NOON. 37 && .MARINE... RELATIVELY LIGHT AND VARIABLE WINDS WILL PICK UP FROM SOUTH TODAY AS PRESSURES START TO FALL RAPIDLY OVER NW TX/OKLAHOMA IN RESPONSE TO PASSING UPPER LEVEL DISTURBANCE. WINDS PICKING UP TO CAUTION LEVELS LATER THIS AFTERNOON FOR COASTAL WATERS AND SCA FOR 20-60 NM REGION TONIGHT. STRONG COLD FRONT ANTICIPATED TO APPROACH COAST AROUND MIDNIGHT AND WINDS SHOULD SIGNIFICANTLY INCREASE BY DAYBREAK TOMORROW TO 20-30 KTS COASTAL WATERS (20-25 KTS BAYS). WAVE HEIGHTS WILL QUICKLY INCREASE THIS AFTERNOON AND TONIGHT AND SHOULD REMAIN ON THE HIGH SIDE THROUGH TOMORROW NIGHT. 37 && .FIRE WEATHER... MUCH DRIER AIRMASS WILL SPREAD INTO SE TX IN THE WAKE OF TONIGHT`S COLD FRONT. NORTHWEST WINDS OF 15-20 MPH AND RH VALUES OF 25-30 PCT MAY RESULT IN AN ELEVATED FIRE DANGER OVER THE NRN/WRN COUNTIES TUE AFTN. WILL LET NEXT SHIFT ASSESS THE NEED TO ISSUE A FIRE WX WATCH FOR THESE AREAS FOR TUE AFTN. THE LOW RH VALUES WILL PERSIST ON WEDNESDAY BUT WINDS SHOULD REMAIN LIGHT. 35/37 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 84 47 61 33 62 / 0 20 0 0 0 HOUSTON (IAH) 82 52 63 36 61 / 0 20 0 0 0 GALVESTON (GLS) 73 55 64 44 59 / 0 20 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR THE FOLLOWING ZONES: AUSTIN...BRAZORIA...CHAMBERS...COLORADO... FORT BEND...GALVESTON...HARRIS...JACKSON...MATAGORDA... WALLER...WHARTON. GM...DENSE FOG ADVISORY UNTIL 10 AM CST THIS MORNING FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM... WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT ADVISORY FROM 4 AM TO 6 PM CST TUESDAY FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT SHOULD EXERCISE CAUTION FROM 3 PM CST THIS AFTERNOON THROUGH THIS EVENING FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 PM CST TUESDAY FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. SMALL CRAFT SHOULD EXERCISE CAUTION FROM 3 PM CST THIS AFTERNOON THROUGH THIS EVENING FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM... WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM. && $$ DISCUSSION...35 AVIATION/MARINE...37 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1213 PM CST SUN FEB 24 2008 .UPDATE... VISIBLE SATELLITE LOOPS SHOW THE LOW CLOUDS OVER THE NORTHWEST AND EASTERN SECTIONS OF NORTH TEXAS ARE SLOWLY BREAKING UP. HAVE SENT THE UPDATES PRIMARILY FOR SKY COVER AND ASSOCIATED TEMPERATURE TRENDS. HAVE ALSO BUMPED UP THE WINDS A LITTLE MORE FOR MONDAY. #58 && .PREV DISCUSSION... /ISSUED 1130 AM CST SUN FEB 24 2008/ AVIATION... HIGH PRESSURE WILL BUILD OVER NORTH TEXAS THIS AFTERNOON WITH CLOUD DECK NORTHWEST-EAST OF THE METROPLEX ERODING AWAY. WINDS BECOME SOUTHERLY 5-10KT TONIGHT AS NEXT LEE-SIDE LOW DEEPENS. EXPECT SOUTH WINDS 15G28KT TO DEVELOP EARLY MONDAY MORNING THEN TURN WESTERLY IN THE AFTERNOONAS DRYLINE/COLD FRONT APPROACHES. 75 PREV DISCUSSION... /ISSUED 545 AM CST SUN FEB 24 2008/ FIRE WEATHER... 621 AM CST. GUSTY SOUTH...THEN WEST-NORTHWEST WINDS AND LOW RH(S) BELOW 30% MONDAY AFTN/EARLY EVENING WILL RESULT IN A PRETTY HIGH GRASS FIRE DANGER OVER THE WRN 1/2 OF N TX. TUES (DUE TO LOW RH(S) AGAIN AND GOOD MIXING OF NW FLOW IN THE BOUNDARY LAYER LOOKS LIKE ANOTHER POSSIBLE RED FLAG DAY. BUT FOR NOW...THE FIRE WX WATCH IS ONLY FOR MONDAY AFTN/EVE FOR THE WRN N TX(SEE ADVISORY LINE BELOW FOR DETAILS). DAY CREW WILL NEED TO INVESTIGATE ANY UPGRADING FOR MONDAY TO A WARNING AND ANY EXTENSION OF THE FIRE WX WATCH INTO TUES (POST- FRONTAL). AVIATION... 545 AM CST ALL AIRPORTS NOW IN NORTH FLOW. WINDS BEHIND WEAK FRONT WILL GRADUALLY SLACKEN AND VEER THIS AFTERNOON...BECOMING S/SE THIS EVENING. CLOUDS WILL BE GENERALLY CLEAR...BUT COLD AIR STRATUS IN OKLAHOMA WILL LIKELY CLIP METRO TAF SITES LATER THIS MORNING. SYNOPTIC MODELS NOT IMPRESSED WITH STRATUS. RUC HAS A GOOD HANDLE ON CURRENT EVOLUTION...PROJECTING CLOUD BANK TO SLOWLY LIFT AND THIN...PASSING EAST OF THE METROPLEX AROUND MIDDAY. 25 PREV DISCUSSION... 342 AM CST SHORT TERM/THROUGH TUESDAY/... WEAK COLD FRONT CONTINUES TO SINK SWD ACROSS THE I-20 CORRIDOR EARLY THIS A.M AND SHOULD WASH OUT OVER SRN COUNTIES TODAY...AS PRESSURE FALLS OFF THE LEE OF THE ROCKIES OCCUR RAPIDLY BY THIS EVENING TO THE NW IN ADVANCE OF STRONG UPPER LOW PUSHING INTO THE WRN CONUS. SOME STRATUS NOTED ON FOG IR OVER MOST OF OKLAHOMA AND MODELS SHOW THAT THIS MAY ENCOMPASS AREAS N OF I-20 A GOOD PART OF THE DAY...THUS KEPT TEMPS COOLER THAN MOS VALUES OVER THIS REGION...THEN WARMER S OF I-20...AS IT SHIFTS EWD INTO THE ARKLATEX/OZARKS THIS EVENING. OTHERWISE...SLY WINDS WILL INCREASE AHEAD OF OUR SYSTEM/COLD FRONT TONIGHT INTO MONDAY...WITH FRONT ARRIVING INTO NW PARTS OF N TX BY MON EVENING. TEMPS MONDAY WILL VERY WARM COMPARED TO TODAY...DUE TO PRE-FRONTAL VEERING OF THE WIND AND COMPRESSIONAL WARMING. SOME VALUES IN THE 80S EXPECTED W OF I-35 CORRIDOR...70 ELSEWHERE. MODELS INDICATE A SLIVER OF PWAT NEAR 1 INCH WILL EXIST OVER FAR ERN COUNTIES WITH INCREASING LAPSE RATES ALOFT...THUS HAVE SOME LOW CHANCES FOR THUNDER OVER FAR ERN PORTIONS OF N TX LATE MON AFTN/MON EVE...LINGERING OVER FAR SE COUNTIES INTO MON A.M. NOTHING SIGNIFICANT EXPECTED WITH RAINFALL OR WITH ANY STORMS. OTHERWISE...WINDY AND COLDER LATER MON NIGHT INTO EARLY TUESDAY...WITH FIRE DANGER LIKELY INCREASING ONCE AGAIN. LONG TERM/TUES EVENING THROUGH NEXT WEEKEND/... DRY FCST EXPECTED MID WEEK WITH A CHILLY MORNING WEDNESDAY...AS SFC HIGH PRESSURE SETTLES OVERHEAD AND DRY NW FLOW ALOFT. HIGHS WEDNESDAY WILL ONLY CREEP INTO THE 50S AND FEEL COLDER THAN THAT DUE TO THE GUSTY N/NW WINDS. S/W RIDGING ALOFT DEVELOPS AHEAD OF NEXT STORM SYSTEM AFFECTS N TX LATE FRIDAY INTO THE WEEKEND...AS LONG-WAVE PATTERN TRANSFORMS INTO A SPLIT-FLOW REGIME...THUS A WARM UP BACK INTO 60S/70S EXPECTED THURS/FRI. WE LEAN TOWARD THE ECMWF OVER THE GFS IN THE LONG TERM PD GOING INTO NEXT WEEKEND...WITH A WEAKER/FURTHER NORTH/AND MORE PROGRESSIVE UPPER DISTURBANCE SCENARIO WITH A BRIEF SHOT FOR SHOWERS AND THUNDERSTORMS...BEFORE DRYING OUT SAT NIGHT/SUN...THEN MAYBE ANOTHER SHOT EARLY NEXT WEEK. MODELS ARE DEFINITELY DIVERGENT WITH THE UPPER LEVEL PATTERN THIS FAR OUT...THUS CONFIDENCE REMAINS PRETTY LOW ON STORM SYSTEM EVOLUTION. 05 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 51 79 42 58 31 / 0 5 5 0 0 WACO, TX 52 79 44 60 32 / 0 5 10 5 0 PARIS, TX 45 74 39 53 28 / 5 20 10 0 0 DENTON, TX 48 77 39 56 30 / 0 5 5 0 0 MCKINNEY, TX 47 76 40 55 28 / 0 10 5 0 0 DALLAS, TX 53 77 42 57 32 / 0 5 5 0 0 TERRELL, TX 48 74 42 56 31 / 0 10 20 0 0 CORSICANA, TX 48 78 45 59 31 / 0 10 30 5 0 TEMPLE, TX 49 80 45 61 31 / 0 5 10 5 0 && .FWD WATCHES/WARNINGS/ADVISORIES... FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING FOR THE FOLLOWING ZONES: TXZ091>093-100>104-115>119-129>134-141>145-156>160-174. && $$ 58/58 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1130 AM CST SUN FEB 24 2008 .AVIATION... HIGH PRESSURE WILL BUILD OVER NORTH TEXAS THIS AFTERNOON WITH CLOUD DECK NORTHWEST-EAST OF THE METROPLEX ERODING AWAY. WINDS BECOME SOUTHERLY 5-10KT TONIGHT AS NEXT LEE-SIDE LOW DEEPENS. EXPECT SOUTH WINDS 15G28KT TO DEVELOP EARLY MONDAY MORNING THEN TURN WESTERLY IN THE AFTERNOONAS DRYLINE/COLD FRONT APPROACHES. 75 && .PREV DISCUSSION... /ISSUED 545 AM CST SUN FEB 24 2008/ FIRE WEATHER... 621 AM CST. GUSTY SOUTH...THEN WEST-NORTHWEST WINDS AND LOW RH(S) BELOW 30% MONDAY AFTN/EARLY EVENING WILL RESULT IN A PRETTY HIGH GRASS FIRE DANGER OVER THE WRN 1/2 OF N TX. TUES (DUE TO LOW RH(S) AGAIN AND GOOD MIXING OF NW FLOW IN THE BOUNDARY LAYER LOOKS LIKE ANOTHER POSSIBLE RED FLAG DAY. BUT FOR NOW...THE FIRE WX WATCH IS ONLY FOR MONDAY AFTN/EVE FOR THE WRN N TX(SEE ADVISORY LINE BELOW FOR DETAILS). DAY CREW WILL NEED TO INVESTIGATE ANY UPGRADING FOR MONDAY TO A WARNING AND ANY EXTENSION OF THE FIRE WX WATCH INTO TUES (POST- FRONTAL). AVIATION... 545 AM CST ALL AIRPORTS NOW IN NORTH FLOW. WINDS BEHIND WEAK FRONT WILL GRADUALLY SLACKEN AND VEER THIS AFTERNOON...BECOMING S/SE THIS EVENING. CLOUDS WILL BE GENERALLY CLEAR...BUT COLD AIR STRATUS IN OKLAHOMA WILL LIKELY CLIP METRO TAF SITES LATER THIS MORNING. SYNOPTIC MODELS NOT IMPRESSED WITH STRATUS. RUC HAS A GOOD HANDLE ON CURRENT EVOLUTION...PROJECTING CLOUD BANK TO SLOWLY LIFT AND THIN...PASSING EAST OF THE METROPLEX AROUND MIDDAY. 25 PREV DISCUSSION... 342 AM CST SHORT TERM/THROUGH TUESDAY/... WEAK COLD FRONT CONTINUES TO SINK SWD ACROSS THE I-20 CORRIDOR EARLY THIS A.M AND SHOULD WASH OUT OVER SRN COUNTIES TODAY...AS PRESSURE FALLS OFF THE LEE OF THE ROCKIES OCCUR RAPIDLY BY THIS EVENING TO THE NW IN ADVANCE OF STRONG UPPER LOW PUSHING INTO THE WRN CONUS. SOME STRATUS NOTED ON FOG IR OVER MOST OF OKLAHOMA AND MODELS SHOW THAT THIS MAY ENCOMPASS AREAS N OF I-20 A GOOD PART OF THE DAY...THUS KEPT TEMPS COOLER THAN MOS VALUES OVER THIS REGION...THEN WARMER S OF I-20...AS IT SHIFTS EWD INTO THE ARKLATEX/OZARKS THIS EVENING. OTHERWISE...SLY WINDS WILL INCREASE AHEAD OF OUR SYSTEM/COLD FRONT TONIGHT INTO MONDAY...WITH FRONT ARRIVING INTO NW PARTS OF N TX BY MON EVENING. TEMPS MONDAY WILL VERY WARM COMPARED TO TODAY...DUE TO PRE-FRONTAL VEERING OF THE WIND AND COMPRESSIONAL WARMING. SOME VALUES IN THE 80S EXPECTED W OF I-35 CORRIDOR...70 ELSEWHERE. MODELS INDICATE A SLIVER OF PWAT NEAR 1 INCH WILL EXIST OVER FAR ERN COUNTIES WITH INCREASING LAPSE RATES ALOFT...THUS HAVE SOME LOW CHANCES FOR THUNDER OVER FAR ERN PORTIONS OF N TX LATE MON AFTN/MON EVE...LINGERING OVER FAR SE COUNTIES INTO MON A.M. NOTHING SIGNIFICANT EXPECTED WITH RAINFALL OR WITH ANY STORMS. OTHERWISE...WINDY AND COLDER LATER MON NIGHT INTO EARLY TUESDAY...WITH FIRE DANGER LIKELY INCREASING ONCE AGAIN. LONG TERM/TUES EVENING THROUGH NEXT WEEKEND/... DRY FCST EXPECTED MID WEEK WITH A CHILLY MORNING WEDNESDAY...AS SFC HIGH PRESSURE SETTLES OVERHEAD AND DRY NW FLOW ALOFT. HIGHS WEDNESDAY WILL ONLY CREEP INTO THE 50S AND FEEL COLDER THAN THAT DUE TO THE GUSTY N/NW WINDS. S/W RIDGING ALOFT DEVELOPS AHEAD OF NEXT STORM SYSTEM AFFECTS N TX LATE FRIDAY INTO THE WEEKEND...AS LONG-WAVE PATTERN TRANSFORMS INTO A SPLIT-FLOW REGIME...THUS A WARM UP BACK INTO 60S/70S EXPECTED THURS/FRI. WE LEAN TOWARD THE ECMWF OVER THE GFS IN THE LONG TERM PD GOING INTO NEXT WEEKEND...WITH A WEAKER/FURTHER NORTH/AND MORE PROGRESSIVE UPPER DISTURBANCE SCENARIO WITH A BRIEF SHOT FOR SHOWERS AND THUNDERSTORMS...BEFORE DRYING OUT SAT NIGHT/SUN...THEN MAYBE ANOTHER SHOT EARLY NEXT WEEK. MODELS ARE DEFINITELY DIVERGENT WITH THE UPPER LEVEL PATTERN THIS FAR OUT...THUS CONFIDENCE REMAINS PRETTY LOW ON STORM SYSTEM EVOLUTION. 05 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 66 51 79 42 58 / 0 0 5 5 0 WACO, TX 71 52 79 44 60 / 0 0 5 10 5 PARIS, TX 57 45 74 39 53 / 5 5 20 10 0 DENTON, TX 62 48 77 39 56 / 0 0 5 5 0 MCKINNEY, TX 61 47 76 40 55 / 0 0 10 5 0 DALLAS, TX 66 53 77 42 57 / 0 0 5 5 0 TERRELL, TX 65 48 74 42 56 / 0 0 10 20 0 CORSICANA, TX 69 48 78 45 59 / 0 0 10 30 5 TEMPLE, TX 74 49 80 45 61 / 0 0 5 10 5 && .FWD WATCHES/WARNINGS/ADVISORIES... FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING FOR THE FOLLOWING ZONES: TXZ091>093-100>104-115>119-129>134-141>145-156>160-174. && $$ 99/05 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 621 AM CST SUN FEB 24 2008 .FIRE WEATHER... GUSTY SOUTH...THEN WEST-NORTHWEST WINDS AND LOW RH(S) BELOW 30% MONDAY AFTN/EARLY EVENING WILL RESULT IN A PRETTY HIGH GRASS FIRE DANGER OVER THE WRN 1/2 OF N TX. TUES (DUE TO LOW RH(S) AGAIN AND GOOD MIXING OF NW FLOW IN THE BOUNDARY LAYER LOOKS LIKE ANOTHER POSSIBLE RED FLAG DAY. BUT FOR NOW...THE FIRE WX WATCH IS ONLY FOR MONDAY AFTN/EVE FOR THE WRN N TX(SEE ADVISORY LINE BELOW FOR DETAILS). DAY CREW WILL NEED TO INVESTIGATE ANY UPGRADING FOR MONDAY TO A WARNING AND ANY EXTENSION OF THE FIRE WX WATCH INTO TUES (POST- FRONTAL). && .PREV DISCUSSION... /ISSUED 545 AM CST SUN FEB 24 2008/ AVIATION... 545 AM CST ALL AIRPORTS NOW IN NORTH FLOW. WINDS BEHIND WEAK FRONT WILL GRADUALLY SLACKEN AND VEER THIS AFTERNOON...BECOMING S/SE THIS EVENING. CLOUDS WILL BE GENERALLY CLEAR...BUT COLD AIR STRATUS IN OKLAHOMA WILL LIKELY CLIP METRO TAF SITES LATER THIS MORNING. SYNOPTIC MODELS NOT IMPRESSED WITH STRATUS. RUC HAS A GOOD HANDLE ON CURRENT EVOLUTION...PROJECTING CLOUD BANK TO SLOWLY LIFT AND THIN... PASSING EAST OF THE METROPLEX AROUND MIDDAY. 25 PREV DISCUSSION... 342 AM CST SHORT TERM/THROUGH TUESDAY/... WEAK COLD FRONT CONTINUES TO SINK SWD ACROSS THE I-20 CORRIDOR EARLY THIS A.M AND SHOULD WASH OUT OVER SRN COUNTIES TODAY...AS PRESSURE FALLS OFF THE LEE OF THE ROCKIES OCCUR RAPIDLY BY THIS EVENING TO THE NW IN ADVANCE OF STRONG UPPER LOW PUSHING INTO THE WRN CONUS. SOME STRATUS NOTED ON FOG IR OVER MOST OF OKLAHOMA AND MODELS SHOW THAT THIS MAY ENCOMPASS AREAS N OF I-20 A GOOD PART OF THE DAY...THUS KEPT TEMPS COOLER THAN MOS VALUES OVER THIS REGION...THEN WARMER S OF I-20...AS IT SHIFTS EWD INTO THE ARKLATEX/OZARKS THIS EVENING. OTHERWISE...SLY WINDS WILL INCREASE AHEAD OF OUR SYSTEM/COLD FRONT TONIGHT INTO MONDAY...WITH FRONT ARRIVING INTO NW PARTS OF N TX BY MON EVENING. TEMPS MONDAY WILL VERY WARM COMPARED TO TODAY...DUE TO PRE-FRONTAL VEERING OF THE WIND AND COMPRESSIONAL WARMING. SOME VALUES IN THE 80S EXPECTED W OF I-35 CORRIDOR...70 ELSEWHERE. MODELS INDICATE A SLIVER OF PWAT NEAR 1 INCH WILL EXIST OVER FAR ERN COUNTIES WITH INCREASING LAPSE RATES ALOFT...THUS HAVE SOME LOW CHANCES FOR THUNDER OVER FAR ERN PORTIONS OF N TX LATE MON AFTN/MON EVE...LINGERING OVER FAR SE COUNTIES INTO MON A.M. NOTHING SIGNIFICANT EXPECTED WITH RAINFALL OR WITH ANY STORMS. OTHERWISE...WINDY AND COLDER LATER MON NIGHT INTO EARLY TUESDAY...WITH FIRE DANGER LIKELY INCREASING ONCE AGAIN. LONG TERM/TUES EVENING THROUGH NEXT WEEKEND/... DRY FCST EXPECTED MID WEEK WITH A CHILLY MORNING WEDNESDAY...AS SFC HIGH PRESSURE SETTLES OVERHEAD AND DRY NW FLOW ALOFT. HIGHS WEDNESDAY WILL ONLY CREEP INTO THE 50S AND FEEL COLDER THAN THAT DUE TO THE GUSTY N/NW WINDS. S/W RIDGING ALOFT DEVELOPS AHEAD OF NEXT STORM SYSTEM AFFECTS N TX LATE FRIDAY INTO THE WEEKEND...AS LONG-WAVE PATTERN TRANSFORMS INTO A SPLIT-FLOW REGIME...THUS A WARM UP BACK INTO 60S/70S EXPECTED THURS/FRI. WE LEAN TOWARD THE ECMWF OVER THE GFS IN THE LONG TERM PD GOING INTO NEXT WEEKEND...WITH A WEAKER/FURTHER NORTH/AND MORE PROGRESSIVE UPPER DISTURBANCE SCENARIO WITH A BRIEF SHOT FOR SHOWERS AND THUNDERSTORMS...BEFORE DRYING OUT SAT NIGHT/SUN...THEN MAYBE ANOTHER SHOT EARLY NEXT WEEK. MODELS ARE DEFINITELY DIVERGENT WITH THE UPPER LEVEL PATTERN THIS FAR OUT...THUS CONFIDENCE REMAINS PRETTY LOW ON STORM SYSTEM EVOLUTION. 05 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 66 51 79 42 58 / 0 0 5 5 0 WACO, TX 71 52 79 44 60 / 0 0 5 10 5 PARIS, TX 57 45 74 39 53 / 5 5 20 10 0 DENTON, TX 62 48 77 39 56 / 0 0 5 5 0 MCKINNEY, TX 61 47 76 40 55 / 0 0 10 5 0 DALLAS, TX 66 53 77 42 57 / 0 0 5 5 0 TERRELL, TX 65 48 74 42 56 / 0 0 10 20 0 CORSICANA, TX 69 48 78 45 59 / 0 0 10 30 5 TEMPLE, TX 74 49 80 45 61 / 0 0 5 10 5 && .FWD WATCHES/WARNINGS/ADVISORIES... FIRE WEATHER WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING FOR THE FOLLOWING ZONES: TXZ091>093-100>104-115>119-129>134-141>145-156>160-174. && $$ 99/05 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 545 AM CST SUN FEB 24 2008 .AVIATION... 545 AM CST ALL AIRPORTS NOW IN NORTH FLOW. WINDS BEHIND WEAK FRONT WILL GRADUALLY SLACKEN AND VEER THIS AFTERNOON...BECOMING S/SE THIS EVENING. CLOUDS WILL BE GENERALLY CLEAR...BUT COLD AIR STRATUS IN OKLAHOMA WILL LIKELY CLIP METRO TAF SITES LATER THIS MORNING. SYNOPTIC MODELS NOT IMPRESSED WITH STRATUS. RUC HAS A GOOD HANDLE ON CURRENT EVOLUTION...PROJECTING CLOUD BANK TO SLOWLY LIFT AND THIN... PASSING EAST OF THE METROPLEX AROUND MIDDAY. 25 && .PREV DISCUSSION... 342 AM CST SHORT TERM/THROUGH TUESDAY/... WEAK COLD FRONT CONTINUES TO SINK SWD ACROSS THE I-20 CORRIDOR EARLY THIS A.M AND SHOULD WASH OUT OVER SRN COUNTIES TODAY...AS PRESSURE FALLS OFF THE LEE OF THE ROCKIES OCCUR RAPIDLY BY THIS EVENING TO THE NW IN ADVANCE OF STRONG UPPER LOW PUSHING INTO THE WRN CONUS. SOME STRATUS NOTED ON FOG IR OVER MOST OF OKLAHOMA AND MODELS SHOW THAT THIS MAY ENCOMPASS AREAS N OF I-20 A GOOD PART OF THE DAY...THUS KEPT TEMPS COOLER THAN MOS VALUES OVER THIS REGION...THEN WARMER S OF I-20...AS IT SHIFTS EWD INTO THE ARKLATEX/OZARKS THIS EVENING. OTHERWISE...SLY WINDS WILL INCREASE AHEAD OF OUR SYSTEM/COLD FRONT TONIGHT INTO MONDAY...WITH FRONT ARRIVING INTO NW PARTS OF N TX BY MON EVENING. TEMPS MONDAY WILL VERY WARM COMPARED TO TODAY...DUE TO PRE-FRONTAL VEERING OF THE WIND AND COMPRESSIONAL WARMING. SOME VALUES IN THE 80S EXPECTED W OF I-35 CORRIDOR...70 ELSEWHERE. MODELS INDICATE A SLIVER OF PWAT NEAR 1 INCH WILL EXIST OVER FAR ERN COUNTIES WITH INCREASING LAPSE RATES ALOFT...THUS HAVE SOME LOW CHANCES FOR THUNDER OVER FAR ERN PORTIONS OF N TX LATE MON AFTN/MON EVE...LINGERING OVER FAR SE COUNTIES INTO MON A.M. NOTHING SIGNIFICANT EXPECTED WITH RAINFALL OR WITH ANY STORMS. OTHERWISE...WINDY AND COLDER LATER MON NIGHT INTO EARLY TUESDAY...WITH FIRE DANGER LIKELY INCREASING ONCE AGAIN. .LONG TERM/TUES EVENING THROUGH NEXT WEEKEND/... DRY FCST EXPECTED MID WEEK WITH A CHILLY MORNING WEDNESDAY...AS SFC HIGH PRESSURE SETTLES OVERHEAD AND DRY NW FLOW ALOFT. HIGHS WEDNESDAY WILL ONLY CREEP INTO THE 50S AND FEEL COLDER THAN THAT DUE TO THE GUSTY N/NW WINDS. S/W RIDGING ALOFT DEVELOPS AHEAD OF NEXT STORM SYSTEM AFFECTS N TX LATE FRIDAY INTO THE WEEKEND...AS LONG-WAVE PATTERN TRANSFORMS INTO A SPLIT-FLOW REGIME...THUS A WARM UP BACK INTO 60S/70S EXPECTED THURS/FRI. WE LEAN TOWARD THE ECMWF OVER THE GFS IN THE LONG TERM PD GOING INTO NEXT WEEKEND...WITH A WEAKER/FURTHER NORTH/AND MORE PROGRESSIVE UPPER DISTURBANCE SCENARIO WITH A BRIEF SHOT FOR SHOWERS AND THUNDERSTORMS...BEFORE DRYING OUT SAT NIGHT/SUN...THEN MAYBE ANOTHER SHOT EARLY NEXT WEEK. MODELS ARE DEFINITELY DIVERGENT WITH THE UPPER LEVEL PATTERN THIS FAR OUT...THUS CONFIDENCE REMAINS PRETTY LOW ON STORM SYSTEM EVOLUTION. 05 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 66 51 79 42 58 / 0 0 5 5 0 WACO, TX 71 52 79 44 60 / 0 0 5 10 5 PARIS, TX 57 45 74 39 53 / 5 5 20 10 0 DENTON, TX 62 48 77 39 56 / 0 0 5 5 0 MCKINNEY, TX 61 47 76 40 55 / 0 0 10 5 0 DALLAS, TX 66 53 77 42 57 / 0 0 5 5 0 TERRELL, TX 65 48 74 42 56 / 0 0 10 20 0 CORSICANA, TX 69 48 78 45 59 / 0 0 10 30 5 TEMPLE, TX 74 49 80 45 61 / 0 0 5 10 5 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 05/25/85 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPOKANE WA 337 AM PST MON FEB 25 2008 .SYNOPSIS... AN UPPER AIR DISTURBANCE WILL DIVE SOUTHEASTWARD ACROSS EASTERN WASHINGTON AND NORTH IDAHO TODAY...BRINGING WITH IT THE POTENTIAL FOR SEVERAL INCHES OF SNOW ABOVE 3000 FEET IN THE CENTRAL AND NORTHERN IDAHO PANHANDLE. HIGH PRESSURE ALOFT WILL THEN BUILD INTO THE REGION TONIGHT AND TUESDAY FOR GENERALLY DRY AND STABLE CONDITIONS. THE NEXT COLD FRONT WILL BRING A RETURN TO UNSETTLED WEATHER WEDNESDAY. && .DISCUSSION...TODAY AND TONIGHT...TWO DISTINCT AREAS OF PRECIPITATION EVIDENT IN REGIONAL RADAR THIS MORNING. FIRST AREA IS LOCATED ACROSS PARTS OF EC/SE WA AND THE NEIGHBORING CENTRAL ID PANHANDLE WHERE FAIRLY WEAK BUT PERSISTENT ISENTROPIC LIFT/WAA HAS SUSTAINED A BROAD SWATH OF MAINLY LIGHT RAIN AND HIGH ELEVATION SNOW ALONG AND SOUTH OF THE I-90 CORRIDOR WITH POCKETS OF MODERATE PRECIP ACROSS THE PALOUSE AND INTO AREAS AROUND ST MARIES. SNOW ACCUMULATION LEVELS HERE APPEAR TO BE NEAR 4000 FT MSL BASED ON AVAILABLE SENSOR DATA...WITH MOST VALLEY LOCATIONS IN THE MID/UPR 30S. THE SECOND AREA...WHICH WILL BE THE MORE IMPORTANT ONE TO EVOLVE THROUGH THE REMAINDER OF THE MORNING....WAS BEGINNING TO EXPAND OVER NERN WA AND NORTH ID. THIS PRECIP WAS DEVELOPING IN REGION OF INCREASING LARGE-SCALE LIFT AHEAD OF A COMPACT/STRENGTHENING VORTICITY MAXIMUM DROPPING SOUTHEAST NEAR THE SOUTH-CENTRAL BC/WA BORDER. LATEST GFS/NAM/RUC INITIALIZED THIS FEATURE REASONABLY WELL...AT LEAST ITS PLACEMENT WITH SOME MINOR DIFFERENCE ON STRENGTH. AS THE UPSTREAM RIDGE BUILDS/SHARPENS...IT WILL FORCE THE AFOREMENTIONED VORT MAX TO ACCELERATE SEWD TRACKING ACROSS EC WA AROUND MID-MORNING...THE CENTRAL IDAHO PANHANDLE BY MIDDAY BEFORE EXITING OUR AREA BY MID-AFTERNOON. THIS VORT WILL BE ACCOMPANIED BY A COMPACT BUT IMPRESSIVE COLD POOL ALOFT WITH 500 MB TEMPS IN THE -30C TO -32C RANGE. AS THIS COLDER AIR ALOFT SLIDES SEWD ALONG AND JUST WEST OF THE ID/MT BORDER IT WILL NOT ONLY SERVE TO STEEPEN LAPSE RATES CONSIDERABLY BUT IT WILL ALSO FORCE SNOW LEVELS DOWNWARD. GIVEN THE CONVECTIVE NATURE OF THE PRECIPITATION...WOULD NOT BE SURPRISED TO SEE BURSTS OF SNOW OR GRAUPEL DOWN TO THE VALLEY FLOORS WITH SEVERAL INCHES OF SNOW FOR THE HIGHER MOUNTAINS NEAR AND ABOVE 3000 FEET. MEANWHILE...FIRST AREA OF PRECIP SHOWING A SHARP BACK EDGE NOW AND MODELS SUGGEST ISENTROPIC LIFT GRADUALLY WEAKENING FROM WEST TO EAST WITH THE FOCUS ACROSS THE CENTRAL ID PANHANDLE FROM ABOUT DAYBREAK ON. FOR TONIGHT...RIDGE ALOFT BUILDS IN FROM THE WEST BUT IT WILL BE A DIRTY ONE WITH PLENTY OF RESIDUAL MOISTURE IN THE LOWER LEVELS. NOT CONVINCED WE WILL SEE APPRECIABLE CLEARING ACROSS EASTERN ZONES THIS AFTERNOON AND IF WE DO SEE CLEARING LATE TODAY/EARLY EVENING...STRATUS AND FOG LIKELY TO MAKE A QUICK RETURN. /KJ TUESDAY THROUGH WEDNESDAY NIGHT...ON TUESDAY A MID LEVEL RIDGE BUILDS ACROSS THE NORTHWEST. WITH LIGHT UPSLOPE BOUNDARY LAYER WINDS AND ABUNDANT LOW LEVEL MOISTURE EXPECT SOME FOG AND LOW STRATUS FORMATION IN THE NORTHEAST VALLEYS TUESDAY MORNING. BY TUESDAY NIGHT MID LEVEL CLOUDS WILL BE ON THE INCREASE AS ISENTROPIC LIFT COMMENCES AHEAD OF THE NEXT FRONTAL SYSTEM. BEST CHANCE OF PRECIP WILL BE ON WEDNESDAY AS THE COLD FRONT CROSSES THE FORECAST AREA. ALONG WITH FRONTAL LIFT THERE WILL BE SOME UPPER LEVEL SUPPORT FROM A JET MAX SLIDING OVER THE REGION. NOT A LOT OF QPF WITH THIS SYSTEM. THE CASCADE CREST WILL SEE A FEW INCHES OF SNOW WITH LIGHT ACCUMULATIONS FOR OTHER MOUNTAIN ZONES. THURSDAY THROUGH MONDAY...A PROGRESSIVE PATTERN WILL CONTINUE THROUGH THE EXTENDED PERIOD. AFTER A DRY DAY ON THURSDAY AND A WEAK SHORTWAVE ON FRIDAY...A MORE ORGANIZED SYSTEM WILL AFFECT THE REGION SATURDAY. AFTER A BREAK ON SUNDAY THE NEXT SYSTEM WILL APPROACH THE REGION ON MONDAY. TEMPERATURES WILL CONTINUE AT OR SLIGHTLY ABOVE SEASONAL NORMALS. /KELCH && .AVIATION... UNSETTLED WX PATTERN ACROSS MUCH OF EASTERN WASHINGTON AND NORTH IDAHO TODAY...AS AN UPPER LEVEL DISTURBANCE TRACKS SOUTHEASTWARD FROM JUST WEST OF CYCG AT 12Z TO NEAR KGEG AT 18Z AND TO GRANGEVILLE AREA BY 00Z. EXPECT WIDESPREAD MVFR/IFR CEILINGS AND VISIBILITIES ACROSS MUCH OF EASTERN WA AND NORTH ID THROUGH AT LEAST 18Z...INCLUDING THE SPOKANE AND COEUR D`ALENE AREA TERMINALS. THE ASSOCIATED PRECIPITATION WILL GRADUALLY END FROM NORTH TO SOUTH DURING THE AFTERNOON. HOWEVER...ABUNDANT LOW LEVEL MOISTURE AND LIGHT WINDS WILL ALLOW FOR STRATUS AND FOG OVER EASTERN WASHINGTON AND NORTHERN IDAHO TONIGHT...WITH MVFR TO LOCALLY IFR CONDITIONS AFTER 06Z. /KJ && .PRELIMINARY POINT TEMPS/POPS... SPOKANE 41 29 45 30 46 31 / 50 0 0 10 40 20 COEUR D`ALENE 42 29 44 29 45 32 / 50 0 0 10 50 20 PULLMAN 44 33 48 33 48 33 / 60 0 0 0 30 10 LEWISTON 49 36 53 36 54 37 / 50 0 0 0 20 10 COLVILLE 43 26 46 28 45 28 / 40 0 10 20 50 20 SANDPOINT 41 28 44 27 45 29 / 60 0 10 10 60 20 KELLOGG 40 30 45 32 44 31 / 70 10 10 10 50 30 MOSES LAKE 45 31 48 30 53 29 / 10 0 0 10 30 10 WENATCHEE 47 32 49 33 51 32 / 10 0 10 10 40 10 OMAK 42 25 44 26 47 23 / 20 0 10 30 40 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...AIR STAGNATION ADVISORY UNTIL NOON PST TODAY FOR NORTHERN PANHANDLE. WA...AIR STAGNATION ADVISORY UNTIL NOON PST TODAY FOR EAST SLOPES NORTHERN CASCADES...NORTHEAST MOUNTAINS...OKANOGAN HIGHLANDS...OKANOGAN VALLEY...SPOKANE AREA...WENATCHEE AREA. && $$ wa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 855 PM CST MON FEB 25 2008 .UPDATE...LATEST RADAR DATA AND SURFACE OBSERVATIONS INDICATED SNOW CONTINUES TO PUSH SOUTHEASTWARD OUT OF SNOW ADVISORY AREAS IN SOUTHERN MOST SECTION OF THE FORECAST AREA. BASED ON LATEST RUC AND NAM/WRF...APPEARS FRONTOGENETIC FORCING SIGNAL SHOULD EXIT AFOREMENTIONED AREA BY 04Z THIS EVENING...WHICH SHOULD END BULK OF SIGNIFICANT SNOWFALL. AS A RESULT...WE ARE PLANNING TO CANCEL SNOW ADVISORY BY 04Z THIS EVENING. ZONE UPDATES AND ACCOMPANYING UPDATES TO GRAPHICS...WEB STORIES...HAZARDOUS WEATHER OUTLOOK...ETC. WILL BE FORTHCOMING BETWEEN 03Z-04Z THIS EVENING. THOMPSON && .PREV DISCUSSION... /ISSUED 223 PM CST MON FEB 25 2008/ SHORT TERM...THROUGH THURSDAY ONGOING WINTER EVENT GRAZING OUR SOUTH TODAY/TONIGHT THE MAIN CONCERN IN THE FORECAST. SECONDARY CONCERN IS STRONG SHORTWAVE/LOW PRESSURE THROUGH THE AREA ON THURSDAY AFTN/NIGHT. BEEN A TOUGH CALL TODAY ON HOW TO HANDLE THIS AS ARX FORECAST AREA HAS BEEN VERY PRECIPITOUSLY HANGING ON NRN FRINGE OF SOME PRETTY HEAVY PRECIPITATION OVER DMX/DVN FORECAST AREA. HAS NOT PRECIPITATED AT ALL NORTH OF A LINE FROM OSAGE TO PRAIRIE DU CHIEN...AND PRECIPITATION HAS LARGELY BEEN RELEGATED TO THE SOUTHERN HALF OF OUR BOTTOM TIER OF COUNTIES...OR ALONG A LINE FROM CHARLES CITY TO LANCASTER. LAPS SOUNDINGS AND RUC SOUNDINGS THROUGH THE DAY CONFIRM A STUBBORN WARM LAYER IN OUR FAR SOUTH TO THE POINT WHERE BULK OF PRECIPITATION THAT HAS FALLEN...HAS BEEN PL/FZRA...WITH SOME SNOW...AND EVEN RAIN MIXING IN AS BOUNDARY LAYER TEMPERATURES ALSO ACROSS THE AREA IN THE 31-34 DEGREE RANGE. SINCE NOON...HAVE SEEN A NICE FRONTOGENESIS BAND SHIFT NORTH AND STALL ON OUR FAR SRN BORDER WITH SNOW BECOMING HEAVIER VIA SPOTTER REPORTS WITH LARGER FLAKES...BUT ROADS FINE GIVEN WARM BOUNDARY LAYER. LARGER SCALE RADAR LOOPS...HOWEVER...INDICATE /AND THIS CONFIRMED IN RUC 600MB FGEN FIELDS/ THAT THIS BAND OF HEAVIER ECHO IS SHIFTING SLOWLY SOUTHEAST NOW AS MAIN UPPER LOW OVER SWRN IA SHIFTS SOUTHEAST THROUGH THE EVENING. HENCE...OUR IDEA IS TO REMOVE THE ADVISORY COMPLETELY WHERE LITTLE FREEZING RAIN/SLEET FELL...AND ONLY MARGINAL ICY PATCHES HAVE BEEN REPORTED. WE WILL TRANSITION WINTER STORM WARNING TO A SNOW ADVISORY FOR A 4 TO 6 HOUR PERIOD OF DECENT SNOW RATE OVER THE SRN HALF OF OUR SOUTHERN THREE COUNTIES THAT WILL LAST INTO EARLY EVENING...WITH TOTAL ACCUMULATIONS OF 2 TO 4 INCHES THERE. LATEST ADVISORY LAYOUT ATTACHED IN CODING AT THE BOTTOM OF THIS PRODUCT. REGARDING THE REST OF THE SHORT TERM TIME FRAME...EXPECT FAIRLY QUIET WEATHER TUESDAY THROUGH WEDNESDAY MORNING. FLURRIES IN COLD ADVECTION STRATOCUMULUS AND BRISK WINDS ON TAP FOR TUESDAY...BUT WILL ALSO SEE SOME SUNSHINE AS WELL. TEMPERATURES REMAINING BELOW NORMAL AS CANADIAN SURFACE HIGH MOVES SOUTH ACROSS THE REGION. 25.12Z GFS HINTING AT WEAK NWLY FLOW WAVE ON WEDNESDAY BUT LITTLE SUPPORT ELSEWHERE FOR THIS FEATURE...SO THIS WILL NEED TO BE WATCHED MORE FOR CLOUD/SUN PERSPECTIVE AND NOT PRECIPITATION. STRONG WAVE THURSDAYHAS GOOD CONSISTENCY/AGREEMENT OUTSIDE THE 25.12Z NAM-WRF WHICH IS DECIDEDLY SLOW. STRONG Q/G FORCING AND WARM ADVECTION INTO THE AREA LATER THURSDAY INTO THURSDAY NIGHT. INCREASED POPS MORE THURSDAY NIGHT WHEN BRUNT OF THE FORCING MOVES THROUGH. MAY VERY WELL SEE SOME DECENT ACCUMULATIONS FROM THIS SYSTEM...1-3 INCHES AS A START BUT WITH UPSIDE IF SYSTEM DIGS FAR ENOUGH SOUTH AND CAN GET IN SOME DEFORMATION/FRONTOGENESIS. MAY VERY WELL LEAD TO MORE ADVISORIES ESPECIALLY NORTH...BUT JURY STILL OUT ON THAT. LONG TERM...FRIDAY THROUGH MONDAY NOT MUCH TIME SPENT ON THIS GIVEN CURRENT WINTER STORM. SAW LITTLE REASON TO DEVIATE MUCH FROM HPC THINKING ON WEATHER/TEMPERATURES...WHICH WILL BE NEARING BACK TO NORMAL AS RIDGING ALOFT IS PROGRESSIVE FROM WEST TO EAST ACROSS THE CONUS. ANOTHER FAIRLY ACTIVE/AMPLIFIED PATTERN IN PLACE BY SUNDAY/MONDAY WITH NEXT CHANCES FOR RAIN/SNOW. THERE HAVE BEEN INDICATIONS FOR A FAIRLY SIGNIFICANT PRECIPITATION EVENT IN THIS TIME PERIOD WHICH WILL NEED TO BE WATCHED CLOSELY. && AVIATION...TONIGHT AND TUESDAY NORTH AND NORTHWEST WINDS WILL CONTINUE TO INCREASE ACROSS THE AREA FOR THIS AFTERNOON/TONIGHT AS LOW PRESSURE TRACKS ACROSS SOUTHERN MO INTO THE LOWER OH VALLEY AND GRADIENT TIGHTENS OVER THE AREA. WITH THE LOW TRACKING THAT FAR SOUTH...-SN NO LONGER EXPECTED AT KRST/KLSE SITES. THE INCREASING NORTH WINDS AND SOME DRIER BOUNDARY LAYER AIR WILL ALLOW VSBYS TO CONTINUE SLOWLY IMPROVE THRU THE AFTERNOON AND EARLY EVENING HOURS. LESS CERTAIN IS DECREASE OF IFR/MVFR CLOUD DECKS OVER THE AREA THRU TONIGHT/TUE. MODEL SOUNDINGS/CROSS-SECTIONS INDICATE PLENTY MOISTURE IN SFC-850MB LAYER TO LINGER OVER THE AREA THRU TUE. HOWEVER...HOLES/CLEAR AREAS IN THE LOW CLOUD DECKS ACROSS PARTS OF CENTRAL MN/NORTHERN WI WITH MORE LOW CLOUD CLEARING OVER NORTHWEST MN. GENERALLY CARRIED BKN MVFR CLOUD DECKS FOR LATER TONIGHT/TUE FOR NOW. LATER CYCLES MAY BE ABLE TO SCATTER THESE CLOUDS OUT IF THE DECREASING TREND OVER NORTHWEST MN CONTINUES. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...SNOW ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ061. MN...NONE. IA...SNOW ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR IAZ029-IAZ030. && $$ SHORT/LONG TERM...BINAU AVIATION...RRS wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 223 PM CST MON FEB 25 2008 .SHORT TERM...THROUGH THURSDAY ONGOING WINTER EVENT GRAZING OUR SOUTH TODAY/TONIGHT THE MAIN CONCERN IN THE FORECAST. SECONDARY CONCERN IS STRONG SHORTWAVE/LOW PRESSURE THROUGH THE AREA ON THURSDAY AFTN/NIGHT. BEEN A TOUGH CALL TODAY ON HOW TO HANDLE THIS AS ARX FORECAST AREA HAS BEEN VERY PRECIPITOUSLY HANGING ON NRN FRINGE OF SOME PRETTY HEAVY PRECIPITATION OVER DMX/DVN FORECAST AREA. HAS NOT PRECIPITATED AT ALL NORTH OF A LINE FROM OSAGE TO PRAIRIE DU CHIEN...AND PRECIPITATION HAS LARGELY BEEN RELEGATED TO THE SOUTHERN HALF OF OUR BOTTOM TIER OF COUNTIES...OR ALONG A LINE FROM CHARLES CITY TO LANCASTER. LAPS SOUNDINGS AND RUC SOUNDINGS THROUGH THE DAY CONFIRM A STUBBORN WARM LAYER IN OUR FAR SOUTH TO THE POINT WHERE BULK OF PRECIPITATION THAT HAS FALLEN...HAS BEEN PL/FZRA...WITH SOME SNOW...AND EVEN RAIN MIXING IN AS BOUNDARY LAYER TEMPERATURES ALSO ACROSS THE AREA IN THE 31-34 DEGREE RANGE. SINCE NOON...HAVE SEEN A NICE FRONTOGENESIS BAND SHIFT NORTH AND STALL ON OUR FAR SRN BORDER WITH SNOW BECOMING HEAVIER VIA SPOTTER REPORTS WITH LARGER FLAKES...BUT ROADS FINE GIVEN WARM BOUNDARY LAYER. LARGER SCALE RADAR LOOPS...HOWEVER...INDICATE /AND THIS CONFIRMED IN RUC 600MB FGEN FIELDS/ THAT THIS BAND OF HEAVIER ECHO IS SHIFTING SLOWLY SOUTHEAST NOW AS MAIN UPPER LOW OVER SWRN IA SHIFTS SOUTHEAST THROUGH THE EVENING. HENCE...OUR IDEA IS TO REMOVE THE ADVISORY COMPLETELY WHERE LITTLE FREEZING RAIN/SLEET FELL...AND ONLY MARGINAL ICY PATCHES HAVE BEEN REPORTED. WE WILL TRANSITION WINTER STORM WARNING TO A SNOW ADVISORY FOR A 4 TO 6 HOUR PERIOD OF DECENT SNOW RATE OVER THE SRN HALF OF OUR SOUTHERN THREE COUNTIES THAT WILL LAST INTO EARLY EVENING...WITH TOTAL ACCUMULATIONS OF 2 TO 4 INCHES THERE. LATEST ADVISORY LAYOUT ATTACHED IN CODING AT THE BOTTOM OF THIS PRODUCT. REGARDING THE REST OF THE SHORT TERM TIME FRAME...EXPECT FAIRLY QUIET WEATHER TUESDAY THROUGH WEDNESDAY MORNING. FLURRIES IN COLD ADVECTION STRATOCUMULUS AND BRISK WINDS ON TAP FOR TUESDAY...BUT WILL ALSO SEE SOME SUNSHINE AS WELL. TEMPERATURES REMAINING BELOW NORMAL AS CANADIAN SURFACE HIGH MOVES SOUTH ACROSS THE REGION. 25.12Z GFS HINTING AT WEAK NWLY FLOW WAVE ON WEDNESDAY BUT LITTLE SUPPORT ELSEWHERE FOR THIS FEATURE...SO THIS WILL NEED TO BE WATCHED MORE FOR CLOUD/SUN PERSPECTIVE AND NOT PRECIPITATION. STRONG WAVE THURSDAYHAS GOOD CONSISTENCY/AGREEMENT OUTSIDE THE 25.12Z NAM-WRF WHICH IS DECIDEDLY SLOW. STRONG Q/G FORCING AND WARM ADVECTION INTO THE AREA LATER THURSDAY INTO THURSDAY NIGHT. INCREASED POPS MORE THURSDAY NIGHT WHEN BRUNT OF THE FORCING MOVES THROUGH. MAY VERY WELL SEE SOME DECENT ACCUMULATIONS FROM THIS SYSTEM...1-3 INCHES AS A START BUT WITH UPSIDE IF SYSTEM DIGS FAR ENOUGH SOUTH AND CAN GET IN SOME DEFORMATION/FRONTOGENESIS. MAY VERY WELL LEAD TO MORE ADVISORIES ESPECIALLY NORTH...BUT JURY STILL OUT ON THAT. .LONG TERM...FRIDAY THROUGH MONDAY NOT MUCH TIME SPENT ON THIS GIVEN CURRENT WINTER STORM. SAW LITTLE REASON TO DEVIATE MUCH FROM HPC THINKING ON WEATHER/TEMPERATURES...WHICH WILL BE NEARING BACK TO NORMAL AS RIDGING ALOFT IS PROGRESSIVE FROM WEST TO EAST ACROSS THE CONUS. ANOTHER FAIRLY ACTIVE/AMPLIFIED PATTERN IN PLACE BY SUNDAY/MONDAY WITH NEXT CHANCES FOR RAIN/SNOW. THERE HAVE BEEN INDICATIONS FOR A FAIRLY SIGNIFICANT PRECIPITATION EVENT IN THIS TIME PERIOD WHICH WILL NEED TO BE WATCHED CLOSELY. && .AVIATION...TONIGHT AND TUESDAY NORTH AND NORTHWEST WINDS WILL CONTINUE TO INCREASE ACROSS THE AREA FOR THIS AFTERNOON/TONIGHT AS LOW PRESSURE TRACKS ACROSS SOUTHERN MO INTO THE LOWER OH VALLEY AND GRADIENT TIGHTENS OVER THE AREA. WITH THE LOW TRACKING THAT FAR SOUTH...-SN NO LONGER EXPECTED AT KRST/KLSE SITES. THE INCREASING NORTH WINDS AND SOME DRIER BOUNDARY LAYER AIR WILL ALLOW VSBYS TO CONTINUE SLOWLY IMPROVE THRU THE AFTERNOON AND EARLY EVENING HOURS. LESS CERTAIN IS DECREASE OF IFR/MVFR CLOUD DECKS OVER THE AREA THRU TONIGHT/TUE. MODEL SOUNDINGS/CROSS-SECTIONS INDICATE PLENTY MOISTURE IN SFC-850MB LAYER TO LINGER OVER THE AREA THRU TUE. HOWEVER...HOLES/CLEAR AREAS IN THE LOW CLOUD DECKS ACROSS PARTS OF CENTRAL MN/NORTHERN WI WITH MORE LOW CLOUD CLEARING OVER NORTHWEST MN. GENERALLY CARRIED BKN MVFR CLOUD DECKS FOR LATER TONIGHT/TUE FOR NOW. LATER CYCLES MAY BE ABLE TO SCATTER THESE CLOUDS OUT IF THE DECREASING TREND OVER NORTHWEST MN CONTINUES. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...SNOW ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR WIZ061. MN...NONE. IA...SNOW ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR IAZ029-IAZ030. && $$ SHORT/LONG TERM...BINAU AVIATION...RRS wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 1155 PM CST MON FEB 25 2008 .UPDATED FOR THE 06Z AVIATION DISCUSSION... .UPDATE... SNOW TAPERING OFF ACROSS MUCH OF THE NORTHERN HALF OF THE CWA...AS SFC LOW SLIDES EAST SOUTHEAST FROM EASTERN MISSOURI TO WESTERN KENTUCKY LATE TONIGHT...AND DRIER AIR SINKING SOUTHWARD FROM THE NORTHERN PLAINS. AREA OF CLEARING PUSHING SOUTH ACROSS ERN SD/WRN MN EXPECTED TO PUSH THROUGH THE NORTHERN/CENTRAL CWA OVERNIGHT. ALSO SEEING TEMPS FALL FASTER THAN EXPECTED IN CLEARING AREA...SO HAVE LOWERED MIN TEMPS ACROSS NORTHWESTERN PORTION OF CWA. ALSO WITH SYSTEM SLIDING EASTWARD...AND PRECIP TAPERING OFF EXPECT MUCH OF THE PRECIP TO COME TO AN END BY MIDNIGHT...WITH ONLY A SMALL AMOUNT LINGERING PAST MIDNIGHT NEAR OTTUMWA/BLOOMFIELD AREAS. HAVE MINIMIZED AREAL EXTENT OF THE WINTER WEATHER ADVISORY TO SOUTHEASTERN THIRD OF THE CWA...WHERE SNOW REMAINS ACROSS THE AREA. BLOWING SNOW THREAT SEEMS TO BE MINIMIZED DUE TO THE SNOW BEING HEAVY AND WET. .PREVIOUS DISCUSSION... ONGOING WINTER WEATHER IS THE MAIN FOCUS THIS FORECAST PACKAGE. CURRENT AXIS OF HEAVIEST PRECIPITATION EXTENDS FROM NEAR ATLANTIC...THROUGH AMES...TO WATERLOO. OVERALL...NORTHWARD PUSH OF WARMER AIR HAS BEEN STRONGER THAN EXPECTED TODAY...AND THIS HAS RESULTED IN A LATER CHANGE OVER TO SNOW. MANY ROADS NORTH AND EAST OF THE DES MOINES AREA ON PARTLY TO MOSTLY SNOW COVERED...WITH MAINLY WET ROADS SOUTH AND EAST OF DES MOINES. AS COLDER AIR FROM THE NORTHWEST CONTINUES TO ERODE THE WARM NOSE ALOFT...PRECIPITATION WILL CHANGE OVER TO ALL SNOW ACROSS THE REMAINDER OF THE FORECAST AREA THROUGH THE LATE AFTERNOON AND EARLY EVENING. THE RUC FN VECTOR CONVERGENCE IN THE 600-500MB LAYER HAS BEEN MODELING THE BAND WELL TODAY...AND IS PROGGED TO CONTINUE SLIDING SOUTHEAST THROUGH THIS EVENING. A FEW LOCATIONS NORTH AND WEST OF DES MOINES HAVE RECEIVED 1 TO 2 INCHES OF SNOW SO FAR...BUT THE SNOW WILL BE ENDING RELATIVELY QUICKLY OVER THE NEXT SEVERAL HOURS. ADDITIONAL SNOW NEAR AND SE OF DES MOINES IS ALSO EXPECTED TO BE RATHER LIMITED BY THE LATE TRANSITION...AND SHOULD BE DIMINISHED TO VERY LIGHT SNOW OR FLURRIES BETWEEN 9 PM AND MIDNIGHT TONIGHT. STORM TOTAL SNOWFALL AMOUNTS IN THE 3 TO 5 INCH RANGE ARE EXPECTED THROUGH TONIGHT...SO HAVE OPTED TO DOWNGRADE THE WINTER STORM WARNING TO A WINTER WEATHER ADVISORY. OTHER CHANGES WERE TO TRIM HEADLINES OVER NW/W COUNTIES...AND EXPAND THE ADVISORY TO INCLUDE SOUTH CENTRAL AND SE COUNTIES. THE ADVISORY WILL ALSO EXPIRE AT MIDNIGHT...RATHER THAN CONTINUE THROUGH THE OVERNIGHT HOURS. WINDS WILL INCREASE THIS EVENING...WITH SUSTAINED SPEEDS IN THE 15 TO 25 MPH RANGE AND GUSTS AROUND 35 MPH OR SO. THE WINDS SHOULD LAG SLIGHTLY BEHIND THE HIGHER INTENSITY SNOW. ALSO...DUE TO THE HEAVY NATURE OF THE SNOW...AND VISIBILITY TRENDS THIS AFTERNOON...DON/T BELIEVE BLOWING SNOW WILL BE MUCH OF A PROBLEM IN TERMS OF VISIBILITY. WILL KEEP A MENTION OF PATCHY BLSN...BUT THE MAIN IMPACT SHOULD BE SHALLOW DRIFTING OVER ROADS. LIGHT SNOW OR FLURRIES WILL LINGER TUESDAY...OTHERWISE EXPECT ANOTHER SHOT OF COLDER AIR INTO WEDNESDAY. A CLIPPER SYSTEM WILL ARRIVE THURSDAY...AND WILL LIKELY HAVE THE HIGHEST IMPACT OVER THE NORTHEAST HALF OF IOWA WITH LIGHT TO POSSIBLY MODERATE ACCUMULATIONS. UPPER FLOW WILL THEN TRANSITION TO ZONAL FLOW WITH WARMING TEMPS THROUGH THE WEEKEND. THE NEXT CHANCE OF PRECIP WILL COME SUNDAY INTO MONDAY. .AVIATION...26/06Z SNOW EXPECTED TO PUSH OUT OF KOTM WITHIN THE NEXT HOUR OR TWO...WITH LIFR CEILINGS EXPECTED AT KDSM AND KOTM THROUGH MUCH OF THE NIGHT. KFOD...KMCW...AND KALO ALL EXPECTED TO MOVE FROM MVFR TO VFR CONDITIONS WITHIN THE NEXT FEW HOURS AS CLOUD SHIELD CONTINUES TO PROGRESS SOUTHEAST...AND DRIER AIR MOVES IN FROM THE NORTHWEST. NORTHWEST WINDS TO REMAIN STRONG THROUGH THE ENTIRE FORECAST PERIOD...WITH VFR CONDITIONS EXPECTED ALL TAF SITES DURING THE DAY TUESDAY. WEAK WAVE TO PUSH SOUTH THROUGH THE AREA...CURRENTLY LOOKING QUITE DRY...AND MAY RESULT IN SOME FLURRIES. WILL HAVE TO MONITOR AS MAY SEE SOME MVFR CIGS PUSH THROUGH THE AREA WITH THIS WAVE. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...KINNEY/MOYER UPDATE/AVIATION...ALBRECHT ia AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 1235 AM EST TUE FEB 26 2008 UPDATED FOR 06Z TAF ISSUANCE .UPDATE... UPDATED TO GO WITH PCLDY SKIES IN THE EVNG ACRS THE KEWEENAW AS DRY AIR OVER MN/SRN ONTARIO AS SHOWN ON 00Z INL RAOB/RECENT TAMDAR SDNG FM YQT HAS INVADED NRN LK SUP AND CAUSED SC TO BREAK UP THERE WITH UNFVRBL NLY FLOW AND ACYC FLOW AT H85. OTRW...CONTINUED INFLUX OF COLDER AIR ACRS LK SUP (00Z H85 TEMP -4C AT GRB...-13C AT INL...THEN -19C AT YPL) WL CAUSE LES TO DVLP OVERNGT. BUT DRYNESS OF AIRMASS AS WELL AS ICE COVER OVER WRN LK SUP AND BTWN THE KEWEENAW AND MQT WL TEND TO LIMIT AMTS. MORE MSTR NOTED NW OF INL/YPL. ARRIVAL OF THIS MSTR ON TUE MRNG IN CONCERT WITH DPVA/HGT FALLS ACCOMPANYING DIGGING SHRTWV NR LK WINNIPEG MAY RESULT IN A BIT MORE LES TMRW. && .SYNOPSIS... SOMEWHAT AMPLIFIED PATTERN OVER NORTH AMERICA AS NOTED ON WATER VAPOR LOOP AND RUC ANALYSIS. MEAN RIDGE IS OVER THE WEST COAST WITH A BROAD TROF OVER THE ERN 2/3RD OF CANADA AND UPR GREAT LAKES AND NE U.S. SRN STREAM SYSTEM MOVING THROUGH THE CENTRAL PLAINS IS PROJECTED TO MOVE THROUGH THE OHIO VALLEY TONIGHT AND TUE AND WILL NOT A SYNOPTIC IMPACT OUR UPR MI WX EXCEPT TO TIGHTEN NRLY GRADIENT OVER THE REGION ON BACK SIDE OF LOW. COLDER AIR MOVING IN LATE TONIGHT AND TUESDAY WITH ADVANCE OF SHORTWAVE FROM SRN MANITOBA WILL HELP GENERATE LES FOR AREAS DOWNSTREAM OF LAKE SUPERIOR IN NRLY FLOW. .SHORT TERM (TONIGHT AND TUESDAY)... BIG QUESTION TONIGHT WILL BE HOW LONG WILL IT TAKE FOR LES BANDS TO DEVELOP AS COLDEST AIR DOESN`T MOVE ACROSS THE AREA UNTIL LATE TONIGHT WITH ARRIVAL OF CLIPPER SHORTWAVE OVER SRN MANITOBA. INITIALLY OVER LAKE SUPERIOR THIS EVENING 850 MB TEMPS ARE FCST TO BE -10C TO -11C WHICH MAY NOT BE COLD ENOUGH TO GENERATE LES. GIVEN MARGINALLY COLD TEMPS FOR EVEN ICE IN THE CLOUDS...HAVE DECIDED TO THROW IN SOME PATCHY FZDZ FOR WEST AND NCNTRL COUNTIES IN NRLY UPSLOPE FLOW. WITH APPROACH OF CLIPPER SHORTWAVE OVERNIGHT...MODELS THEN SHOW 850 MB TEMPS LOWERING TO -16 TO -18 LATE TONIGHT WHICH SHOULD HELP GENERATE SOME LES. SO GIVEN THE SLOWER ADVANCE OF COLD AIR UNTIL LATE TONIGHT GENERALLY TRIMMED BACK ACCUMS TONIGHT TO INCH OR LESS OVER THE FAVORED NRLY UPSLOPE AREAS IN WEST AND NCNTRL ZONES...BUT KEPT IN LIKELY POPS FOR THE OVERNIGHT IN THESE COUNTIES. BY TUE...THE COLDEST AIR IS OVER THE UPR GREAT LAKES WITH 850 MB TEMPS LOWERING TO AROUND -19C. HOWEVER...SFC-850 MB FLOW IS ALSO BECOMING SHARPLY ANTICYCLONIC BY THIS TIME WITH DRY AIR AT LOW-LEVELS ADVECTING IN FROM ONTARIO. THE DRY AIR COMBINED WITH INCREASED SUN ANGLE/DIURNAL HEATING THIS TIME OF YEAR...MAY DISRUPT LES BANDS A BIT DURING THE DAY. FOR THESE REASONS ALSO TRIMMED BACK ACCUMS TO AROUND AN INCH FOR WEST AND CENTRAL ZONES IN UPSLOPE NRLY FLOW. THERE COULD BE SOME LOCALLY HIGHER AMOUNTS (AROUND 2 INCHES) BETWEEN MARQUETTE AND MUNISING WHERE MODELS INDICATE LOW-LEVEL CONVERGENCE WILL BE MAXIMIZED. && .LONG TERM (TUESDAY NIGHT THROUGH MONDAY)... MAIN FORECAST ISSUE IS AMOUNT OF SNOWFALL TUESDAY NIGHT THROUGH THURSDAY. SEVERAL MODELS ARE BEGINNING TO SHOW SIGNS OF A DOMINANT BAND FORMING NEAR MUNISING TUESDAY EVENING AND PERSISTING INTO WEDNESDAY MORNING. REGIONAL GEM...NAM...AND LOCAL HI-RES WRF-ARW ALL SHOW THIS FEATURE...ALTHOUGH IT ISN`T PRESENT IN THE GFS. WILL GO AHEAD AND INCREASE QPF/SNOW AMOUNTS IN THIS GENERAL AREA...AND IF THIS FEATURE CONTINUES TO APPEAR IN FUTURE MODEL RUNS...A HEADLINE MAY BE NEEDED FOR ALGER COUNTY. ACROSS THE REST OF THE LAKE SUPERIOR SHORELINE...NORTHWEST WINDS WILL RESULT IN LIGHT LES CONTINUING FROM TUESDAY NIGHT THROUGH THURSDAY MORNING. INVERSION HEIGHTS WILL REMAIN BELOW 5000 FT...ALTHOUGH ALMOST THE ENTIRE INVERSION LIES WITHIN THE FAVORABLE DENDRITIC GROWTH ZONE. LAKE EFFECT WILL COME TO AN END DURING THE DAY ON THURSDAY AS A RIDGE BEGINS TO BUILD INTO THE REGION AND WINDS BACK TO THE SOUTHWEST. THERE IS THE POTENTIAL FOR A SHORT PERIOD OF LAKE EFFECT SNOW ALONG THE LAKE MICHIGAN SHORELINE WITH S-SW WINDS AND 850MB TEMPERATURES AROUND -15C THURSDAY AFTERNOON...ALTHOUGH CONFIDENCE IN TEMPERATURES AND WINDS MATCHING AT THE SAME TIME PERIOD IS NOT HIGH ENOUGH TO ADD ANY POPS AT THIS TIME. CONFIDENCE THROUGH EXTENDED PERIOD DECREASES AS MODEL SOLUTIONS BEGIN TO DIVERGE BY SUNDAY. MODELS ARE IN GENERAL AGREEMENT THAT A LOW WILL MOVE FROM THE MN ARROWHEAD ACROSS LAKE SUPERIOR DURING THE DAY ON FRIDAY...WITH HIGH PRESSURE BUILDING IN BEHIND THE LOW FOR SATURDAY. ECMWF WAS THE PREFERRED MODEL THROUGH THIS PORTION OF THE PERIOD...AND IS THEN BLENDED WITH 00Z NCEP ENSEMBLE MEAN AND 00Z CANADIAN GLOBAL SOLUTIONS. A WEAK LOW PRESSURE SYSTEM SHOULD THEN PUSH THROUGH THE GREAT LAKES BY MONDAY MORNING. RELIED HEAVILY ON HPC GUIDANCE FOR DAYS 6 AND 7 WHEN MODELS WERE DIVERGENT. MAIN CHANGE THAT USING HPC GUIDANCE CAUSED WAS AN ADDITION OF CHANCE POPS TO SUNDAY AND MONDAY WITH THE LOW ENTERING THE AREA. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... INFLUX OF DRIER AIR IN NRN MN/SRN ONTARIO AS SHOWN ON 00Z INL RAOB/ RECENT TAMDAR SDNG FM YQT AS WELL AS ACYC FLOW AT H85 HAS CAUSED VFR CONDITIONS AT CMX INTO THE OVERNGT. DESPITE THESE NEGATIVES...LONGER FETCH/FVRBL NLY UPSLOPE FLOW HAS PERSISTED THE SC MVFR CIG AT SAW. WITH WEAKENING DRY ADVECTION LATER TNGT...SUSPECT MVFR CIG WL DVLP AT CMX WHILE STEADIER SHSN THAT RESTRICT VSBY TO MVFR RANGE COMMENCE AT SAW. BEST CHC FOR MORE FREQUENT SHSN AND LOWER VSBY... MVFR AT CMX/IFR AT SAW...WL BE TUE MRNG INTO THE AFTN WHEN DIGGING SHRTWV DRAGS COLDER LLVL AIR INTO THE UPR LKS AND INVRN BASE LIFTS TO 5-6K FT. ARRIVAL OF THE COLDER AIR WL ALSO RESULT IN GUSTY WINDS AT TIMES. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT NORTHERLY WINDS TO DOMINATE THROUGH MIDWEEK. AN INCREASING PRESSURE GRADIENT BETWEEN LOW PRESSURE MOVING INTO THE OHIO VALLEY AND HIGH PRESSURE OVER THE PLAINS WILL RESULT IN WINDS TO 30 KT FROM TUE AFTERNOON THROUGH TUE NIGHT. HEAVY FREEZING SPRAY IS ALSO EXPECTED TUE INTO WED AS COLDER AIR MOVES IN. AS THE LOW MOVES E ON WED THE NORTHERLY GRADIENT WILL SLACKEN AS WINDS QUICKLY DIE DOWN BLO 20 KT BY LATE WED. SRLY WINDS WILL INCREASE TO 25 TO 30 KT BY LATE THU AND THU NIGHT AS ANOTHER CLIPPER SYSTEM DIVES INTO THE NRN PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING FROM 7 AM TUESDAY TO 7 PM EST WEDNESDAY FOR LMZ248-250. && $$ UPDATE...KC SHORT TERM...VOSS LONG TERM...TAG MARINE...VOSS AVIATION...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 321 AM CST TUE FEB 26 2008 .DISCUSSION... QUIET WEATHER CONTINUES THIS MORNING AS FORCING MECHANISMS ARE WEAK... OR NON EXISTENT. SFC PATTERN REFLECTS CWA IN GRADIENT BETWEEN DEPARTING OHIO VALLEY SFC LOW AND HIGH PRESSURE OVER WRN HIGH PLAINS. AN AMPLIFYING MID LVL TROF...WITH A POCKET OF -35C AT 50H...IS PUSHING INTO THE NWRN CWA THIS MORNING. FLURRIES ARE BEING SQUEEZED OUT OF THE MOISTENING COLUMN AS LAPSE RATES STEEPEN TEMPORARILY. THIS SCENARIO WILL SPREAD SE TODAY ACROSS CWA WITH NO ACCUMULATIONS EXPECTED. BOTH LATEST RUC AND GFS HINT AT A SECONDARY SHORTWAVE MIGRATING SOUTH TODAY ACROSS ERN CWA WITH PERHAPS SOME ADDITIONAL FLURRIES POSSIBLE. STILL HAVE SOME POTENTIAL FOR LES OVER ERN WI ZONES HOWEVER SUMMATION OF LES PARAMETERS INDICATES SIGNIFICANT ACCUMULATIONS NOT LIKELY. EXPECT SOME DEVELOPMENT EARLY THIS MORNING AS MID LVL FEATURE WILL ENHANCE THERMAL/MOISTURE PROPERTIES OF SYNOPTIC BACKGROUND. HOWEVER...OVERALL FETCH NOT VERY FAVORABLE AS 85H TRAJECTORY MAINTAINS TOO MUCH NW VS NRLY FLOW. THERE MAY BE JUST TOO MUCH ICE COVER ON SUPERIOR TO ALLOW ENOUGH MSTR FLUX INTO BL AIR. EVEN NORMALLY EXCITABLE HI RES 4KM NMM SIMULATED REFLECTIVITY PRODUCT NOT SUGGESTING ORGANIZED EVENT. BUFKIT PROFILES...BOTH GFS/NAM...RATHER MEAGER WITH PRODUCTION OF LAKE INDUCED CAPE/EQ LEVEL AS INVERSION HEIGHTS REMAIN NEAR 4/5K. LES POTENTIAL SHOULD GRADUALLY DECREASE BY WEDNESDAY AFTERNOON AS INSTABILITY LESSENS AND DEEP LAYER OF DRYING MOVES IN. EXTENDED...THUR THROUGH SUNDAY... MEAN MID LVL RIDGE REMAINS OVER WRN CONUS WITH SEVERAL SHORTWAVES AMPLIFYING OVER CWA. FIRST ONE OCCURS THUR/FRI. MDL CONSENSUS IS FAIRLY GOOD THIS FAR OUT WITH REGARD TO OVERALL FCST OF SNOWFALL SPREADING EAST THURSDAY. MDL TIMING VARIES FROM FASTEST..ECMWF..TO SLOWER NAM/GFS/CMC...WITH UKM IN BETWEEN. BOTH EC/GFS SUGGEST THAT PROGRESSIVE NATURE OF MID LVL FLOW BY FRIDAY WILL KEEP SYSTEM MOVING EAST... LIMITING SIGNIFICANT SNOWFALL. OF COURSE...WITH THIS LACKLUSTER SNOW SEASON AS OF LATE....2 INCHES MIGHT SEEM SIGNIFICANT TO SOME. ANOTHER CHANCE OF SNOW SAT/SUN WITH AMPLIFYING SHORTWAVE. EC/GFS HAVE SOME TIMING DIFFERENCES BOTH BOTH FOCUS BEST CHANCE OF ACCUMULATION OVER FAR NRN CWA. && .AVIATION... ONTINUED COLD AIR ADVECTION TODAY...AS WELL AS A SHORTWAVE...WILL LEAD TO MVFR OR LOW VFR CEILINGS TODAY. AREAS OF LIGHT SNOW OR FLURRIES ARE ALSO POSSIBLE...AND MAY REDUCE VSBYS TO 3 TO 5 MILES IN SPOTS DURING THE DAY. SNOW SHOWERS MAY BE A BIT HEAVIER ALONG PORTIONS OF THE SOUTH SHORE OF LAKE SUPERIOR...ESPECIALLY EAST OF KASX...TOWARD KIWD. && POINT TEMPS/POPS... DLH 20 4 19 3 / 10 10 10 10 INL 21 0 18 -3 / 10 10 10 20 BRD 28 6 23 7 / 10 10 10 20 HYR 23 3 21 -3 / 10 10 10 10 ASX 24 7 19 3 / 20 20 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. $$ CANNON/MELDE mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 402 AM CST TUE FEB 26 2008 .DISCUSSION... COLD FRONT ENTERING NEARSHORE WATERS EARLY THIS MORNING. RUC...NAM12 AND GFS INDICATE QUITE STRONG WINDS SURFACE TO 850 MB LAYER BEHIND FRONT. ALSO...PRESSURE GRADIENT BEHIND FRONT ALREADY TIGHTENING. WE WILL ISSUE A WIND ADVISORY FOR CWFA FOR TODAY INDICATING 20-25 MPH INLAND AREAS AND 25-30 MPH NEAR THE COAST. LINGERING CONVECTION NOTED EAST CENTRAL PORTION OF CWFA DUE TO REGION BEING UNDER RR QUAD OF UPPER JET CORE AND ENOUGH MOISTURE MID LEVELS. THIS HOWEVER IS EXPECTED TO MOVE OUT OF REGION BEFORE SUNRISE. WE WILL MENTION ISOLATED SHOWERS FOR THAT PORTION FOR EARLY MORNING PERIOD ONLY (FOR ZFPHGX). PW VALUES DROPPING OVER REGION AS PER GOES SOUNDER LOOP. NORTHWEST PORTION OF CWFA APPROACHING HALF AN INCH BUT STILL MOIST SOUTHEAST REGION PROBABLY NEAR AN INCH. STRONG COLD AIR ADVECTION WILL DROP TEMPERATURES TO THE 30S LATER TONIGHT INLAND AREAS WITH READINGS NEAR OR SLIGHTLY BELOW FREEZING FAR NORTHERN ZONES. HIGH PRESSURE CENTER WILL SETTLE OVER FAR SOUTH TEXAS TOWARD WEDNESDAY MORNING WITH WINDS ACROSS OUR CWFA DECREASING QUITE A BIT ACROSS CENTRAL AND NORTHERN SECTIONS. UPPER FLOW BECOMING MORE ZONAL THURSDAY WITH RETURN FLOW AT LOWER LEVELS DUE TO HIGH SHIFTING TO SOUTHEAST CONUS. LOWER LEVEL MOISTURE WILL INCREASE DURING THE LATTER PART OF THIS WEEKDAY WITH SUSTAINED ONSHORE FLOW. WE SHALL SEE A WARM UP THURSDAY AND INTO THE WEEKEND ALONG WITH INCREASING HUMIDITY VALUES. WE DID CONTINUE TO MENTION SLIGHT CHANCE POPS END OF WEEK AND CHANCE (30 PERCENT) WEEKEND. VERTICAL PROFILES WOULD INDICATE POSSIBLE THUNDERSTORMS DURING THE WEEKEND. GFS SHOWING DEVELOPING UPPER LOW OVER NORTHWEST OLD MEXICO BY FRIDAY WITH UPPER FLOW OVER TEXAS BECOMING MORE SOUTHWESTERLY. REINFORCING HIGH PRESSURE AT THE SURFACE WILL MOVE TO THE EASTERLY PORTION OF CONUS SATURDAY MAKING THE FLOW ACROSS THE NORTH CENTRAL AND NORTHEAST GULF MORE EASTERLY. GFS INDICATE UPPER LOW OVER OLD MEXICO WILL WEAKEN...OPEN UP AND MOVE EAST LATE IN THE WEEKEND WHILE A DEVELOPING LARGE UPPER TROUGH IS INDICATED ...EXTENDING FROM THE GREAT LAKES TO THE WESTERN HIGH PLAINS. THIS SYSTEM WILL USHER A STRONG COLD FRONT TO OUR REGION MONDAY. 37 && .AVIATION... SOME SHRA HAVE DEVELOPED GENERALLY FROM THE CONROE-HUNTSVILLE AREA AND THEN OFF TO THE EAST AND NORTHEAST INTO LOUISIANA. EXPECT THIS STUFF TO MOVE OFF TO THE EAST SOME TIME BEFORE OR RIGHT AROUND SUNRISE. LOOKS LIKE A GOOD PORTION OF THE AREA (ESPECIALLY UP NORTH) WILL SEE A BKN DECK OF MID AND HIGH LEVEL CLOUDS THIS MORNING. ALL CLOUDS SHOULD DISSIPATE OR MOVE ON OUT SOME TIME LATE THIS AFTERNOON. STRONG NORTH WINDS WILL BE THE MAIN AVIATION CONCERN TODAY. EXPECT SUSTAINED 20 TO 25 KNOT WINDS INLAND AND 20 TO 30 KNOT WINDS ALONG THE COAST. WE`LL LIKELY SEE SOME HIGHER GUSTS. GRADIENT RELAXES SIGNIFICANTLY LATE THIS AFTERNOON INLAND AND LATE THIS EVENING ALONG THE COAST. SKC TONIGHT. 42 && .MARINE... WILL HAVE SMALL CRAFT ADVISORIES IN EFFECT FOR THE BAYS THROUGH 6 PM AND FOR THE GULF WATERS THROUGH MIDNIGHT FOR STRONG NORTH WINDS INCREASING TO 20 TO 30 KNOTS. HAVE TODAY`S SEAS INCREASING TO 5 TO 7 FEET NEARSHORE AND 7 TO 10 FEET OFFSHORE. BOTH WINDS AND SEAS WILL RELAX TONIGHT AS THE GRADIENT WEAKENS WITH SURFACE HIGH PRESSURE BUILDING INTO THE AREA...BUT WE`LL PROBABLY NEED SOME KIND OF CAUTION OR ADVISORY FLAGS EVEN AFTER MIDNIGHT FOR PORTIONS OF OUR GULF WATERS. WINDS WILL SWING AROUND TO THE EAST AND SOUTHEAST WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT. CAUTION AND/OR ADVISORY FLAGS WILL BE POSSIBLE AGAIN ON THURSDAY AS THIS ONSHORE FLOW STRENGTHENS. 42 && .FIRE WEATHER... WILL DROP THE FIRE WEATHER WATCH FOR TODAY. ALTHOUGH WINDS WILL BE STRONG AND THE GROUND REMAINS DRY...RELATIVE HUMIDITY VALUES THIS AFTERNOON ARE NOT ANTICIPATED TO FALL INTO A 20% TO 25% RANGE. 42 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 61 32 64 42 71 / 0 0 0 0 0 HOUSTON (IAH) 62 35 63 42 70 / 0 0 0 0 0 GALVESTON (GLS) 63 44 59 48 67 / 10 0 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...WIND ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: AUSTIN...BRAZORIA...BRAZOS...BURLESON...CHAMBERS... COLORADO...FORT BEND...GALVESTON...GRIMES...HARRIS... HOUSTON...JACKSON...LIBERTY...MADISON...MATAGORDA... MONTGOMERY...POLK...SAN JACINTO...TRINITY...WALKER... WALLER...WASHINGTON...WHARTON. GM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY. SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. && $$ 37/42 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 1141 PM CST MON FEB 25 2008 .UPDATE... PREFRONTAL TROUGH HAS MOVED SOUTHEAST OF OUR AREA AND HAS TAKEN THE SHOWERS AND STORMS WITH IT. WILL REMOVE POPS FROM THE FORECAST WHERE MENTIONED FOR TONIGHT. OTHERWISE, SOUTH CENTRAL TEXAS FORECASTS ARE ON TRACK. && .PREV DISCUSSION... /ISSUED 1130 PM CST MON FEB 25 2008/ AVIATION... VFR CONDITIONS WILL PERSIST. NORTHERLY WINDS OF 20 TO 30 KTS OVERNIGHT AND THROUGH TUESDAY WILL WEAKEN AS SUNSET APPROACHES. PREV DISCUSSION... /ISSUED 945 PM CST MON FEB 25 2008/ UPDATE... STRONG TO SEVERE THUNDERSTORMS HAVE DEVELOPED ACROSS AREAS EAST OF SMITHVILLE TO GONZALES. WILL INCREASE POPS AND MENTION SEVERE STORMS POSSIBLE FOR FAYETTE AND LAVACA COUNTIES. PREV DISCUSSION... /ISSUED 833 PM CST MON FEB 25 2008/ UPDATE... AT 8 PM CDT...COLD FRONT WAS MOVING SOUTHEAST AT 35 MPH AND EXTENDED ALONG A ROCKDALE TO AUSTIN TO BOERNE TO UVALDE TO EAGLE PASS LINE AT 8 PM. SOME SHOWERS WERE NOTED ALONG THE FRONT NORTHEAST OF TAYLOR. THE RUC HAS GENERATED SOME SHOWERS ALONG THE FRONT ACROSS SOUTH CENTRAL TEXAS AND WILL EXPAND SLIGHT CHANCE OF SHOWERS A LITTLE FURTHER TO WEST, THOUGH NOT QUITE TO THE I-35 CORRIDOR. ALSO, TEMPERATURES SHOWED LITTLE DROP OFF BEHIND THE FRONT WITH A DROP OFF NOTED BEHIND A SECOND BOUNDARY ALONG A WACO TO BRADY TO OZONA TO FORT STOCKTON LINE. WILL SLOW TEMPERATURE AND DEWPOINT FALL BASED ON EXPECTED MOVEMENT OF THIS BOUNDARY ACROSS SOUTH CENTRAL TEXAS DURING THE OVERNIGHT HOURS. WIND PROFILES OVER NORTHERN AND WESTERN TEXAS SHOW 45 MPH IN THE LOWER LEVELS. WILL HOLD OFF FOR NOW, HOWEVER LATER SHIFTS MAY HAVE TO ISSUE WIND ADVISORIES FOR ALL OR PART OF SOUTH CENTRAL TEXAS. FIRE WEATHER... RED FLAG WARNING IN EFFECT UNTIL 6 PM CST TUESDAY LOOKS ON TRACK. NOT MUCH RECOVERY OF RELATIVE HUMIDITIES IS EXPECTED OVERNIGHT. PREV DISCUSSION... /ISSUED 526 PM CST MON FEB 25 2008/ AVIATION... DRY SOUTHERLY WINDS GUSTING TO 20 KTS WILL BE REPLACED WITH DRY NORTHERLY WINDS 20 TO 30 KTS BETWEEN 03Z AND 04Z AS A STRONG COLD FRONT PLOWS THROUGH TEXAS. THE BLUSTERY WINDS WILL PERSIST THROUGH 00Z TOMORROW. SKY CONDITIONS WILL REMAIN VFR WITH SCT CIRRUS CLOUDS. PREV DISCUSSION... /ISSUED 324 PM CST MON FEB 25 2008/ DISCUSSION... WINDY...HOT...AND DRY CONDITIONS WILL CONTINUE INTO THE EVENING HOURS AHEAD OF THE COLD FRONT. WINDS WILL SHIFT TO NORTHWEST TO NORTHERLY ACROSS THE ENTIRE REGION BEFORE MIDNIGHT...BUT WILL REMAIN NEAR 20 MPH. THE STRONG NORTHERLY WINDS WILL CONTINUE THROUGH TUESDAY AFTERNOON...WITH GUSTS TO 35 MPH POSSIBLE...BUT SUSTAINED WINDS WILL REMAIN JUST BELOW WIND ADVISORY CRITERIA. A MUCH COOLER AIRMASS WILL FILTER INTO SOUTH CENTRAL TEXAS DURING THE OVERNIGHT HOURS...WITH HIGHS TUESDAY EXPECTED TO BE SOME 20 DEGREES BELOW MONDAY`S. CLEAR SKIES OVERNIGHT AND DECREASING WINDS WILL PROMOTE GOOD RADIATIONAL COOLING LEADING TO TEMPERATURES BELOW FREEZING ACROSS THE HILL COUNTRY...AND NEAR FREEZING ACROSS THE REST OF THE AREA. WINDS WILL BEGIN TO SHIFT BACK TO THE SOUTHEAST ON WEDNESDAY ALLOWING SHALLOW GULF MOISTURE TO RETURN. THIS INCREASE IN MOISTURE SHOULD BE EVIDENT EARLY THURSDAY MORNING WITH PATCHY FOG DEVELOPMENT EXPECTED IN THE NEAR-SUNRISE HOURS MAINLY ALONG AND SOUTHEAST OF THE I-35 CORRIDOR. NEARLY ZONAL FLOW ALOFT WILL ENABLE A MODEST WARMING TREND THROUGH THE END OF THE WORK WEEK AND INTO THE WEEKEND. THE NEXT BEST CHANCE FOR RAIN APPEARS TO BE LATE FRIDAY INTO SATURDAY. LOW LEVEL MOISTURE WILL HAVE HAD MORE TIME TO DEEPEN AND A TROUGH PASSING WELL TO THE NORTH MAY PROVIDE ENOUGH INSTABILITY FOR SOME CONVECTIVE ACTIVITY. ATTM...LOW-END CHC POPS SEEM REASONABLE. MODELS ARE STILL INDICATING A POLAR COLD FRONT ARRIVING LATE IN THE WEEKEND TO EARLY NEXT WEEK. FIRE WEATHER... STRONG SOUTHWEST WINDS WILL CONTINUE INTO THE EVENING HOURS AHEAD OF A STRONG COLD FRONT. THE FRONT WILL MOVE INTO SOUTH CENTRAL TEXAS THIS EVENING AND OVERNIGHT AND BRING EVEN DRIER AIR TO THE ENTIRE REGION. GUSTY NORTHWEST WINDS OF 15 TO 25 MPH WILL BEGIN THIS EVENING AND CONTINUE THROUGH MUCH OF TUESDAY. THE WINDS WILL COMBINE WITH RELATIVE HUMIDITY VALUES FALLING INTO THE TEENS TO PRODUCE CONDITIONS FAVORABLE FOR THE SPREAD OF FIRE FOR SEVERAL HOURS. && .PRELIMINARY POINT TEMPS/POPS... AUSTIN CAMP MABRY 47 66 37 70 41 / 0 0 0 0 0 AUSTIN BERGSTROM INTL AIRPORT 49 62 32 65 33 / 0 0 0 0 0 DEL RIO INTL AIRPORT 53 73 38 69 43 / 0 0 0 0 0 SAN ANTONIO INTL AIRPORT 48 69 34 69 38 / 0 0 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 6 PM CST TUESDAY FOR THE FOLLOWING COUNTIES: ATASCOSA...BANDERA...BASTROP...BEXAR...BLANCO...BURNET...CALDWELL... COMAL...DE WITT...DIMMIT...EDWARDS...FAYETTE...FRIO...GILLESPIE... GONZALES...GUADALUPE...HAYS...KARNES...KENDALL...KERR...KINNEY... LAVACA...LEE...LLANO...MAVERICK...MEDINA...REAL...TRAVIS...UVALDE... VAL VERDE...WILLIAMSON...WILSON...ZAVALA. && $$ 04/06 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX 1130 PM CST MON FEB 25 2008 .AVIATION... VFR CONDITIONS WILL PERSIST. NORTHERLY WINDS OF 20 TO 30 KTS OVERNIGHT AND THROUGH TUESDAY WILL WEAKEN AS SUNSET APPROACHES. && .PREV DISCUSSION... /ISSUED 945 PM CST MON FEB 25 2008/ UPDATE... STRONG TO SEVERE THUNDERSTORMS HAVE DEVELOPED ACROSS AREAS EAST OF SMITHVILLE TO GONZALES. WILL INCREASE POPS AND MENTION SEVERE STORMS POSSIBLE FOR FAYETTE AND LAVACA COUNTIES. PREV DISCUSSION... /ISSUED 833 PM CST MON FEB 25 2008/ UPDATE... AT 8 PM CDT...COLD FRONT WAS MOVING SOUTHEAST AT 35 MPH AND EXTENDED ALONG A ROCKDALE TO AUSTIN TO BOERNE TO UVALDE TO EAGLE PASS LINE AT 8 PM. SOME SHOWERS WERE NOTED ALONG THE FRONT NORTHEAST OF TAYLOR. THE RUC HAS GENERATED SOME SHOWERS ALONG THE FRONT ACROSS SOUTH CENTRAL TEXAS AND WILL EXPAND SLIGHT CHANCE OF SHOWERS A LITTLE FURTHER TO WEST, THOUGH NOT QUITE TO THE I-35 CORRIDOR. ALSO, TEMPERATURES SHOWED LITTLE DROP OFF BEHIND THE FRONT WITH A DROP OFF NOTED BEHIND A SECOND BOUNDARY ALONG A WACO TO BRADY TO OZONA TO FORT STOCKTON LINE. WILL SLOW TEMPERATURE AND DEWPOINT FALL BASED ON EXPECTED MOVEMENT OF THIS BOUNDARY ACROSS SOUTH CENTRAL TEXAS DURING THE OVERNIGHT HOURS. WIND PROFILES OVER NORTHERN AND WESTERN TEXAS SHOW 45 MPH IN THE LOWER LEVELS. WILL HOLD OFF FOR NOW, HOWEVER LATER SHIFTS MAY HAVE TO ISSUE WIND ADVISORIES FOR ALL OR PART OF SOUTH CENTRAL TEXAS. FIRE WEATHER... RED FLAG WARNING IN EFFECT UNTIL 6 PM CST TUESDAY LOOKS ON TRACK. NOT MUCH RECOVERY OF RELATIVE HUMIDITIES IS EXPECTED OVERNIGHT. PREV DISCUSSION... /ISSUED 526 PM CST MON FEB 25 2008/ AVIATION... DRY SOUTHERLY WINDS GUSTING TO 20 KTS WILL BE REPLACED WITH DRY NORTHERLY WINDS 20 TO 30 KTS BETWEEN 03Z AND 04Z AS A STRONG COLD FRONT PLOWS THROUGH TEXAS. THE BLUSTERY WINDS WILL PERSIST THROUGH 00Z TOMORROW. SKY CONDITIONS WILL REMAIN VFR WITH SCT CIRRUS CLOUDS. PREV DISCUSSION... /ISSUED 324 PM CST MON FEB 25 2008/ DISCUSSION... WINDY...HOT...AND DRY CONDITIONS WILL CONTINUE INTO THE EVENING HOURS AHEAD OF THE COLD FRONT. WINDS WILL SHIFT TO NORTHWEST TO NORTHERLY ACROSS THE ENTIRE REGION BEFORE MIDNIGHT...BUT WILL REMAIN NEAR 20 MPH. THE STRONG NORTHERLY WINDS WILL CONTINUE THROUGH TUESDAY AFTERNOON...WITH GUSTS TO 35 MPH POSSIBLE...BUT SUSTAINED WINDS WILL REMAIN JUST BELOW WIND ADVISORY CRITERIA. A MUCH COOLER AIRMASS WILL FILTER INTO SOUTH CENTRAL TEXAS DURING THE OVERNIGHT HOURS...WITH HIGHS TUESDAY EXPECTED TO BE SOME 20 DEGREES BELOW MONDAY`S. CLEAR SKIES OVERNIGHT AND DECREASING WINDS WILL PROMOTE GOOD RADIATIONAL COOLING LEADING TO TEMPERATURES BELOW FREEZING ACROSS THE HILL COUNTRY...AND NEAR FREEZING ACROSS THE REST OF THE AREA. WINDS WILL BEGIN TO SHIFT BACK TO THE SOUTHEAST ON WEDNESDAY ALLOWING SHALLOW GULF MOISTURE TO RETURN. THIS INCREASE IN MOISTURE SHOULD BE EVIDENT EARLY THURSDAY MORNING WITH PATCHY FOG DEVELOPMENT EXPECTED IN THE NEAR-SUNRISE HOURS MAINLY ALONG AND SOUTHEAST OF THE I-35 CORRIDOR. NEARLY ZONAL FLOW ALOFT WILL ENABLE A MODEST WARMING TREND THROUGH THE END OF THE WORK WEEK AND INTO THE WEEKEND. THE NEXT BEST CHANCE FOR RAIN APPEARS TO BE LATE FRIDAY INTO SATURDAY. LOW LEVEL MOISTURE WILL HAVE HAD MORE TIME TO DEEPEN AND A TROUGH PASSING WELL TO THE NORTH MAY PROVIDE ENOUGH INSTABILITY FOR SOME CONVECTIVE ACTIVITY. ATTM...LOW-END CHC POPS SEEM REASONABLE. MODELS ARE STILL INDICATING A POLAR COLD FRONT ARRIVING LATE IN THE WEEKEND TO EARLY NEXT WEEK. FIRE WEATHER... STRONG SOUTHWEST WINDS WILL CONTINUE INTO THE EVENING HOURS AHEAD OF A STRONG COLD FRONT. THE FRONT WILL MOVE INTO SOUTH CENTRAL TEXAS THIS EVENING AND OVERNIGHT AND BRING EVEN DRIER AIR TO THE ENTIRE REGION. GUSTY NORTHWEST WINDS OF 15 TO 25 MPH WILL BEGIN THIS EVENING AND CONTINUE THROUGH MUCH OF TUESDAY. THE WINDS WILL COMBINE WITH RELATIVE HUMIDITY VALUES FALLING INTO THE TEENS TO PRODUCE CONDITIONS FAVORABLE FOR THE SPREAD OF FIRE FOR SEVERAL HOURS. && .PRELIMINARY POINT TEMPS/POPS... AUSTIN CAMP MABRY 47 66 37 70 41 / 0 0 0 0 0 AUSTIN BERGSTROM INTL AIRPORT 49 62 32 65 33 / 0 0 0 0 0 DEL RIO INTL AIRPORT 53 73 38 69 43 / 0 0 0 0 0 SAN ANTONIO INTL AIRPORT 48 69 34 69 38 / 0 0 0 0 0 && .EWX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 6 PM CST TUESDAY FOR THE FOLLOWING COUNTIES: ATASCOSA...BANDERA...BASTROP...BEXAR...BLANCO...BURNET...CALDWELL... COMAL...DE WITT...DIMMIT...EDWARDS...FAYETTE...FRIO...GILLESPIE... GONZALES...GUADALUPE...HAYS...KARNES...KENDALL...KERR...KINNEY... LAVACA...LEE...LLANO...MAVERICK...MEDINA...REAL...TRAVIS...UVALDE... VAL VERDE...WILLIAMSON...WILSON...ZAVALA. && $$ 04/06 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TALLAHASSEE FL 850 AM EST TUE FEB 26 2008 ...SEVERE WEATHER EXPECTED TODAY WITH WINDY CONDITIONS THROUGH WEDNESDAY... ...FREEZING TEMPERATURES EXPECTED WEDNESDAY NIGHT... .UPDATE...LATEST WATER VAPOR/RUC H5 COMPOSITE SHOWS A VIGOROUS SHORT WAVE TROUGH MOVING INTO THE WRN OH/TN VALLEYS. A 40-50 KT WSW LOW LEVEL JET COMBINED WITH FAVORABLE UPPER DIFFLUENCE AHEAD OF THE TROUGH IS SETTING THE STAGE FOR SEVERE WEATHER ACROSS MUCH OF THE REGION TODAY. A COLD FRONT EXTENDS FROM NRN AL TO ERN LA WITH A PREFRONTAL TROUGH JUST AHEAD OF THE COLD FRONT FROM NWRN GA TO THE WRN FL PANHANDLE. A SQUALL LINE IS ORIENTED ALONG THIS SURFACE TROUGH AND IS MOVING INTO A REGION OF MOIST UNSTABLE AIR MASS (MID 60F DEW POINTS SURGING NWD INTO SERN AL/ERN FL PANHANDLE). THIS SQUALL LINE IS MOVING FAIRLY RAPIDLY EWD (50-60 KTS)...AND WILL AFFECT OUR WRN ZONES BETWEEN 14Z AND 16Z...AND AREAS TO THE EAST INTO THE AFTERNOON. HAVE COORDINATED WITH THE SPC...AND A SVR TSTM WATCH WILL BE IN EFFECT FOR OUR ENTIRE CWFA UNTIL 20Z. && .MARINE...EXERCISE CAUTION CONDITIONS CONTINUE AT BUOY 42039 AND WINDS WILL PICK UP TO ADVISORY CRITERION LATER THIS MORNING. SEAS WILL FOLLOW SHORTLY THEREAFTER. WE COULD EASILY SEE SUSTAINED WINDS AROUND 25 KNOTS...ESPECIALLY BEHIND THE FRONT LATER TODAY AND TONIGHT. WINDS WILL NOT DROP BELOW ADVISORY CRITERIA UNTIL WEDNESDAY EVENING. && .AVIATION...IFR CIGS AND MVFR/IFR VIS ARE STILL AFFECTING MOST OF THE TAF SITES THIS MORNING...BUT CONDITIONS ARE IMPROVING QUICKLY AT DHN OUT AHEAD OF THE SQUALL LINE. THESE IMPROVEMENTS WILL BE SHORT-LIVED...AS THE STRONG TO POTENTIALLY SEVERE THUNDERSTORMS APPROACH THE AREA WITH FREQUENT LIGHTNING...WIND GUSTS OF 40 MPH OR GREATER...TORRENTIAL DOWNPOURS...AND POSSIBLY SOME HAIL. THESE STORMS WILL CONTINUE TO MARCH QUICKLY EASTWARD THROUGH THE MORNING HOURS...AND EVENTUALLY IMPACT ALL OF THE TAF SITES FROM NW TO SE. && .HYDROLOGY...MARIANNA CRESTED A FEW FEET ABOVE FLOOD STAGE...WITH THE FLOOD WAVE TRAVELING DOWNSTREAM AND FLOODING ALTHA TODAY AND LASTING INTO FRIDAY. BLOXHAM SHOULD BE CRESTING TODAY A FEW FEET ABOVE FLOOD STAGE. HAVANA HAS CRESTED...BUT WILL CONTINUE TO EXPERIENCE MODERATE FLOODING THROUGH THE END OF THE WEEK. AREAL FLOODING CONTINUES IN SRN LEON COUNTY DUE TO MUNSON SLOUGH DRAINAGE. TODAY`S CONVECTION SHOULD PROGRESS EWD AT A DECENT CLIP...SO BASIN AVERAGE QPF SHOULD REMAIN UNDER AN INCH. FOR MORE DETAILS ON THE RIVERINE FLOODING...SEE THE NWS TALLAHASSEE WEB PAGE FOR THE LATEST FLOOD WARNINGS AND RIVER FORECASTS PROVIDED THROUGH OUR LOCAL AHPS SITE. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 71 40 53 24 58 / 80 20 00 00 00 PANAMA CITY 70 41 53 35 60 / 90 10 00 00 00 DOTHAN 66 34 51 29 59 / 90 10 00 00 00 ALBANY 68 35 51 28 57 / 90 10 00 00 00 VALDOSTA 72 39 52 28 57 / 80 20 00 00 00 CROSS CITY 77 42 54 27 59 / 80 60 00 00 00 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...LAKE WIND ADVY ALL ZONES 15-23Z TODAY. FIRE WEATHER WATCH WEDNESDAY AFTERNOON FOR THE FOLLOWING ZONES: COFFEE...DALE...GENEVA...HENRY...HOUSTON. GA...LAKE WIND ADVY ALL ZONES 15-23Z TODAY. FIRE WEATHER WATCH WEDNESDAY AFTERNOON FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...BROOKS...CALHOUN...CLAY... COLQUITT...COOK...DECATUR...DOUGHERTY...EARLY...GRADY... IRWIN...LANIER...LEE...LOWNDES...MILLER...MITCHELL... QUITMAN...RANDOLPH...SEMINOLE...TERRELL...THOMAS...TIFT... TURNER...WORTH. FL...LAKE WIND ADVY ALL ZONES 15-23Z TODAY. RED FLAG WARNING FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING FOR THE FOLLOWING ZONES: BAY...CALHOUN...DIXIE... FRANKLIN...GADSDEN...GULF...HOLMES...INLAND WALTON... JACKSON...JEFFERSON...LAFAYETTE...LEON...LIBERTY...MADISON... TAYLOR...WAKULLA...WASHINGTON. GM...SMALL CRAFT ADVISORY FROM 8 AM TODAY TO 7 PM EST WED ALL LEGS. && $$ JAMSKI/GOULD fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 636 AM CST TUE FEB 26 2008 .UPDATE... MADE SOME TWEAKS TO GOING GRIDS TO MATCH CURRENT OBS...TRENDS AND CONSISTENCY. UPDATED GRIDS WILL BE OUT SHORTLY. -HOWERTON && .AVIATION... FAIRLY SIGNIFICANT CONCERN IS MVFR CLOUDS ACROSS MUCH OF NEBRASKA. OPERATIONAL MODELS ARE EITHER CLUELESS OR SERIOUSLY STRUGGLING WITH THIS LOW LEVEL MOISTURE. RUC SORT OF HINTED AT IT AND THE GLOBAL FORECAST SYSTEM MODEL BUFR SOUNDING VALID AT 1500 UTC AT KRSL SORT OF HINTED AT IT AS WELL. MM5 SEEMED TO HAVE THE BEST HANDLE WITH MUCH LOWER RELATIVE HUMIDITY MOVING ACROSS EASTERN KS AT THIS TIME AND HIGHER RELATIVE HUMIDITY MOVING OUT OF NEBRASKA. IT SHOWS THE MOISTURE IN NEBRASKA ADVECTING ACROSS NE KS WITH GRAZING SHOT AT KSLN. OPTED TO NOT CUT IT THAT CLOSE AND INCLUDE TEMPO GROUP AT KRSL AS WELL GIVEN CURRENT SATELLITE TREND. OTHERWISE WITH HIGH PRESSURE BUILDING ACROSS THE AREA...WINDS SHOULD GRADUALLY DIMINISH THROUGHOUT THE DAY AND BECOME LIGHT AND VARIABLE BY TONIGHT. -HOWERTON && .PREV DISCUSSION... /ISSUED 251 AM CST TUE FEB 26 2008/ DISCUSSION... SYNOPSIS: A DISCERNIBLE 500-MB SHORTWAVE...MOVING S/SE OVER ERN ND @ 12 MIDNIGHT WILL RACE S/SE OVER THE GREAT PLAINS TODAY...CROSSING THE KS/MO BORDER ~12 NOON...THEN THE LWR MS VALLEY ~6PM THIS EVENING. THIS FEATURE WILL OPERATE IN TANDEM WITH AN ULTRA-HIGH AMPLITUDE MID-UPR RIDGE POSITIONED ALONG THE WEST COAST TO INDUCE A FAST NW FLOW REGIME THAT PREVAILS THRU EARLY THU MORNING. AT THAT TIME A 2ND 500-MB SHORTWAVE WILL RIDE E OVER THE PACIFIC COAST UPR RIDGE TO INDUCE DEAMPLIFICATION LATE WED NIGHT. THE 500-MB SHORTWAVE THEN SPRINTS SE ACROSS THE NRN ROCKIES...INDUCING SFC-700MB TROFFING ALONG THE FRONT RANGE THU MORNING. THE RESULT WILL BE A WARMING TREND THAT`LL OCCUR WED & THU BEFORE A COLD FRONT OF PACIFIC ORIGIN SWEEPS SE THROUGH THE AREA THU NIGHT. TODAY: INTENSE LOW PRESSURE...CENTERED OVER MID-MS VALLEY EARLY THIS MORNING...WILL CONTINUE TO MOVE E TOWARD THE APPALACHIANS ALLOWING SKIES TO CLEAR IN GENERAL W-E MANNER OVER THE KICT CWFA. HOWEVER...NLY SFC-850MB FLOW REMAINS QUITE STRONG THRU MID-AFTERNOON...SO BRISK N/NW WINDS TO PERSIST THRU LATE AFTERNOON. MOREOVER THE LACKING OF A DOWNSLOPE COMPONENT WILL KEEP PREVENT SIGNIFICANT WARMING...SO HAVE HELD MAXES TO ~40F WITH SE KS ON COOLER SIDE OF FENCE. TONIGHT: A VERY WEAK SFC TROF DRIFTS E ACROSS NRN PLAINS TO INDUCE LWR-DECK FLOW TO BACK TO A LIGHT WLY COMP. WITH DRY AIRMASS IN PLACE KEPT MINS INTACT WITH LWR 20S ASSIGNED TO ALL AREAS. WED-THU: WARMING TREND SLATED ALL AREAS FOR REASONS STATED IN "SYNOPSIS" HOWEVER EASED UP ON "DEGREE" OF WARMUP ON THU AS 500-MB SHORTWAVE WILL SPREAD CONSIDERABLE CIRROSTRATUS SE ACROSS KS. AS SUCH LOWERED MAXES ALL AREAS TO MID/UPR 50S WITH NE CORRIDOR ON COOLER END OF THIS THERMAL SPECTRUM. THU NIGHT: STRENGTHENING 500-MB SHORTWAVE SURGING E/SE ACROSS FAR NRN PLAINS WILL SWEEP A WEAK PACIFIC COLD FRONT SE ACROSS KS. AIRMASS DRY...SO FRONTAL PASSAGE TO INDUCE NO MORE THAN A WIND SHIFT. DUE TO COLD FRONT`S LATE ARRIVAL...HAVE RAISED MINS ACROSS SC & SE KS TO 35-40F. THIS WEEKEND: FAST ZONAL FLOW PREVAILS FOR MOST OF PERIOD & WITH DEEP SW/WLY FLOW OVER THE PLAINS...SAT TO BE WARMEST DAY OF THE WEEK WITH HIGHS FLIRTING WITH 70F ALONG WRN CORRIDOR. LATE SAT NIGHT/EARLY SUNDAY MORNING A STRONGER & DEEPENING POSITIVELY-TILTED UPR-DECK TROF SPRINTS E/SE ACROSS NRN & C PLAINS THAT`LL FORCE FAIRLY POTENT COLD FRONT SE ACROSS THE KICT CWFA LATE SAT NIGHT. CONVERGENCE ALONG THE BOUNDARY APPEARS SUFFICIENT TO INTRO ~20% -SHRA TO SE KS LATE SAT NIGHT. WITH UPR-DECK TROF CONTINUING TO DEEPEN ON SUNDAY...HAVE INTRODUCED EMBEDDED TSRA TO ALL AREAS ON SUN. && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 41 23 53 31 / 0 0 0 0 HUTCHINSON 40 22 53 29 / 0 0 0 0 NEWTON 39 22 52 29 / 0 0 0 0 ELDORADO 39 22 51 29 / 0 0 0 0 WINFIELD-KWLD 42 24 53 31 / 0 0 0 0 RUSSELL 41 22 53 27 / 0 0 0 0 GREAT BEND 41 23 54 29 / 0 0 0 0 SALINA 41 23 51 28 / 0 0 0 0 MCPHERSON 40 23 52 28 / 0 0 0 0 COFFEYVILLE 40 22 53 30 / 0 0 0 0 CHANUTE 38 21 51 28 / 0 0 0 0 IOLA 37 21 51 28 / 0 0 0 0 PARSONS-KPPF 39 21 52 29 / 0 0 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 613 AM CST TUE FEB 26 2008 .AVIATION... FAIRLY SIGNIFICANT CONCERN IS MVFR CLOUDS ACROSS MUCH OF NEBRASKA. OPERATIONAL MODELS ARE EITHER CLUELESS OR SERIOUSLY STRUGGLING WITH THIS LOW LEVEL MOISTURE. RUC SORT OF HINTED AT IT AND THE GLOBAL FORECAST SYSTEM MODEL BUFR SOUNDING VALID AT 1500 UTC AT KRSL SORT OF HINTED AT IT AS WELL. MM5 SEEMED TO HAVE THE BEST HANDLE WITH MUCH LOWER RELATIVE HUMIDITY MOVING ACROSS EASTERN KS AT THIS TIME AND HIGHER RELATIVE HUMIDITY MOVING OUT OF NEBRASKA. IT SHOWS THE MOISTURE IN NEBRASKA ADVECTING ACROSS NE KS WITH GRAZING SHOT AT KSLN. OPTED TO NOT CUT IT THAT CLOSE AND INCLUDE TEMPO GROUP AT KRSL AS WELL GIVEN CURRENT SATELLITE TREND. OTHERWISE WITH HIGH PRESSURE BUILDING ACROSS THE AREA...WINDS SHOULD GRADUALLY DIMINISH THROUGHOUT THE DAY AND BECOME LIGHT AND VARIABLE BY TONIGHT. -HOWERTON && .DISCUSSION... .AVIATION... FAIRLY SIGNIFICANT CONCERN IS MVFRR ACROSS WESTERN KS AND MUCH OF NEBRASKA. OPERATIONAL MODELS ARE EITHER CLUELESS OR SERIOUSLY STRUGGLING WITH THIS LOW LEVEL MOISTURE. RUC SORT OF HINTED AT IT AND THE GLOBAL FORECAST SYSTEM MODEL BUFR SOUNDING AT 1500 UTC AT KRSL SORT OF HINTED AT IT AS WELL. MM5 SEEMED TO HAVE THE BEST HANDLE WITH MUCH LOWER RELATIVE HUMIDITY MOVING ACROSS EASTERN KS AT THIS TIME. IT SHOWS THAT THE MOISTURE IN NEBRASKA WILL LIKELY BE SHUNTED ACROSS NE KS WITH GRAZING SHOT AT KSLN. OPTED TO NOT CUT IT THAT CLOSE AND INCLUDE TEMPORARY GROUP AT KRSL AS WELL GIVEN SATELLITE TREND. OTHERWISE WITH HIGH PRESSURE BUILDING ACROSS THE AREA...WINDS SHOULD GRADUALLY DIMINISH THROUGHOUT THE DAY AND BECOME LIGHT AND VARIABLE BY TONIGHT. -HOWERTON && .PREV DISCUSSION... /ISSUED 251 AM CST TUE FEB 26 2008/ DISCUSSION... SYNOPSIS: A DISCERNIBLE 500-MB SHORTWAVE...MOVING S/SE OVER ERN ND @ 12 MIDNIGHT WILL RACE S/SE OVER THE GREAT PLAINS TODAY...CROSSING THE KS/MO BORDER ~12 NOON...THEN THE LWR MS VALLEY ~6PM THIS EVENING. THIS FEATURE WILL OPERATE IN TANDEM WITH AN ULTRA-HIGH AMPLITUDE MID-UPR RIDGE POSITIONED ALONG THE WEST COAST TO INDUCE A FAST NW FLOW REGIME THAT PREVAILS THRU EARLY THU MORNING. AT THAT TIME A 2ND 500-MB SHORTWAVE WILL RIDE E OVER THE PACIFIC COAST UPR RIDGE TO INDUCE DEAMPLIFICATION LATE WED NIGHT. THE 500-MB SHORTWAVE THEN SPRINTS SE ACROSS THE NRN ROCKIES...INDUCING SFC-700MB TROFFING ALONG THE FRONT RANGE THU MORNING. THE RESULT WILL BE A WARMING TREND THAT`LL OCCUR WED & THU BEFORE A COLD FRONT OF PACIFIC ORIGIN SWEEPS SE THROUGH THE AREA THU NIGHT. TODAY: INTENSE LOW PRESSURE...CENTERED OVER MID-MS VALLEY EARLY THIS MORNING... WILL CONTINUE TO MOVE E TOWARD THE APPALACHIANS ALLOWING SKIES TO CLEAR IN GENERAL W-E MANNER OVER THE KICT CWFA. HOWEVER...NLY SFC-850MB FLOW REMAINS QUITE STRONG THRU MID-AFTERNOON...SO BRISK N/NW WINDS TO PERSIST THRU LATE AFTERNOON. MOREOVER THE LACKING OF A DOWNSLOPE COMPONENT WILL KEEP PREVENT SIGNIFICANT WARMING...SO HAVE HELD MAXES TO ~40F WITH SE KS ON COOLER SIDE OF FENCE. TONIGHT: A VERY WEAK SFC TROF DRIFTS E ACROSS NRN PLAINS TO INDUCE LWR-DECK FLOW TO BACK TO A LIGHT WLY COMP. WITH DRY AIRMASS IN PLACE KEPT MINS INTACT WITH LWR 20S ASSIGNED TO ALL AREAS. WED-THU: WARMING TREND SLATED ALL AREAS FOR REASONS STATED IN "SYNOPSIS" HOWEVER EASED UP ON "DEGREE" OF WARMUP ON THU AS 500-MB SHORTWAVE WILL SPREAD CONSIDERABLE CIRROSTRATUS SE ACROSS KS. AS SUCH LOWERED MAXES ALL AREAS TO MID/UPR 50S WITH NE CORRIDOR ON COOLER END OF THIS THERMAL SPECTRUM. THU NIGHT: STRENGTHENING 500-MB SHORTWAVE SURGING E/SE ACROSS FAR NRN PLAINS WILL SWEEP A WEAK PACIFIC COLD FRONT SE ACROSS KS. AIRMASS DRY...SO FRONTAL PASSAGE TO INDUCE NO MORE THAN A WIND SHIFT. DUE TO COLD FRONT`S LATE ARRIVAL...HAVE RAISED MINS ACROSS SC & SE KS TO 35-40F. THIS WEEKEND: FAST ZONAL FLOW PREVAILS FOR MOST OF PERIOD & WITH DEEP SW/WLY FLOW OVER THE PLAINS...SAT TO BE WARMEST DAY OF THE WEEK WITH HIGHS FLIRTING WITH 70F ALONG WRN CORRIDOR. LATE SAT NIGHT/EARLY SUNDAY MORNING A STRONGER & DEEPENING POSITIVELY-TILTED UPR-DECK TROF SPRINTS E/SE ACROSS NRN & C PLAINS THAT`LL FORCE FAIRLY POTENT COLD FRONT SE ACROSS THE KICT CWFA LATE SAT NIGHT. CONVERGENCE ALONG THE BOUNDARY APPEARS SUFFICIENT TO INTRO ~20% -SHRA TO SE KS LATE SAT NIGHT. WITH UPR-DECK TROF CONTINUING TO DEEPEN ON SUNDAY...HAVE INTRODUCED EMBEDDED TSRA TO ALL AREAS ON SUN. && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 41 23 53 31 / 0 0 0 0 HUTCHINSON 40 22 53 29 / 0 0 0 0 NEWTON 39 22 52 29 / 0 0 0 0 ELDORADO 39 22 51 29 / 0 0 0 0 WINFIELD-KWLD 42 24 53 31 / 0 0 0 0 RUSSELL 41 22 53 27 / 0 0 0 0 GREAT BEND 41 23 54 29 / 0 0 0 0 SALINA 41 23 51 28 / 0 0 0 0 MCPHERSON 40 23 52 28 / 0 0 0 0 COFFEYVILLE 40 22 53 30 / 0 0 0 0 CHANUTE 38 21 51 28 / 0 0 0 0 IOLA 37 21 51 28 / 0 0 0 0 PARSONS-KPPF 39 21 52 29 / 0 0 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION...AVIATION DISCUSSION. NATIONAL WEATHER SERVICE SPRINGFIELD MO 536 AM CST TUE FEB 26 2008 .DISCUSSION... COLDER AIR WAS ONCE AGAIN ADVECTING INTO THE AREA ON GUSTY NORTHWEST WINDS FOLLOWING A FRONTAL PASSAGE MONDAY EVENING. LIGHT SNOW AND FLURRIES WERE SPREADING ACROSS THE OZARKS EARLY THIS MORNING JUST AHEAD OF THE MID LEVEL TROUGH AS DEPICTED BY REGIONAL PROFILERS. WITH STRONG COLD AIR ADVECTION AND LINGERING STRATUS TEMPERATURES WILL STRUGGLE TO CLIMB TODAY. READINGS WILL REMAIN IN THE 30S AND WELL BELOW LATE FEBRUARY NORMALS. FLURRIES ALSO REMAIN POSSIBLE THROUGH THE MORNING. WINDS WILL SUBSIDE LATE TODAY AND TONIGHT AS A SURFACE RIDGE SHIFTS EAST INTO MISSOURI. SOUTHERLY WINDS WILL MAKE THEIR RETURN WEDNESDAY AS THE SURFACE HIGH MIGRATES TO THE EAST. TEMPERATURES WILL REMAIN BELOW NORMAL BUT MAKE A MORE SUBSTANTIAL REBOUND ACROSS SOUTHEAST KANSAS AND FAR WESTERN MISSOURI WHERE SOUTHERLY WINDS RETURN EARLIER IN THE DAY. SOUTHERLY WINDS AND RESULTING WARM AIR ADVECTION WILL INCREASE THURSDAY AND THURSDAY NIGHT AS THE PRESSURE GRADIENT TIGHTENS IN ADVANCE OF A DEVELOPING FRONT ACROSS THE PLAINS. MODELS SUGGEST INCREASING ISENTROPIC ASCENT ESPECIALLY JUST TO THE NORTH FROM NORTHERN KANSAS INTO NORTHERN MISSOURI AS A MINOR SHORTWAVE TRACKS INTO THE NORTHERN PLAINS. THIS WILL RESULT AN INCREASE IN CLOUD COVER AND WILL HAVE TO WATCH THE POTENTIAL OF LIGHT SHOWERS. IF THICKER CLOUD COVER DEVELOPS TEMPERATURES MAY NOT BE AS WARM AS PROGGED. THE NEXT FRONT WILL PUSH ACROSS THE OZARKS EARLY FRIDAY AS A DEEPER SHORTWAVE TROUGH DROPS INTO THE NORTHERN PLAINS. SCATTERED SHOWERS MAY DEVELOP AS THE FRONT ADVANCES INTO FAR SOUTHERN MISSOURI FRIDAY MORNING. THE MODIFIED PACIFIC AIRMASS FOLLOWING THE FRONT WILL BE RELATIVELY MILD AND TEMPERATURES WILL REBOUND BACK INTO THE 50S ON SATURDAY. THE ACTIVE PATTERN WILL CONTINUE WITH THE NEXT FRONT TAKING SHAPE TO OUR WEST THIS WEEKEND. THIS FRONT AND ASSOCIATED CHANCE OF SHOWERS WILL PUSH INTO THE REGION SUNDAY. THE LATEST GFS MODEL IS MORE PROGRESSIVE WITH THIS SYSTEM AND SWEEPS IT TO THE EAST OF THE AREA ON MONDAY. HOWEVER THE ECMWF MODEL CONTINUES TO SIGNAL THE POSSIBILITY OF WINTRY WEATHER ON MONDAY. MUCH UNCERTAINTY REMAINS ON THE EVOLUTION OF THIS SYSTEM. FOSTER && .AVIATION... A VERY DEEP COLD FRONT PASSED THROUGH THE JOPLIN AND SPRINGFIELD AIRPORTS EARLY THIS MORNING. MID LEVEL BAROCLINICITY AND ASSOCIATED SHARP LOCAL RISES IN POTENTIAL TEMPERATURE SURFACES BROUGHT LIGHT SNOW TO MOST LOCATIONS ACROSS THE OZARKS. A SHARP MID LEVEL WIND SHIFT FROM THE NORTH NORTHWEST HAS CAUSED A LARGE SURGE OF DOWNWARD MOVING PARCELS ACROSS THE EASTERN PLAINS OVER THE PAST COUPLE OF HOURS. ULTIMATELY PRESSURE ADVECTION CAUSING STRONG DOWNGLIDE HAS TAKEN OVER VERTICAL MOTIONS...AND CLEARING HAS SPED UP ACROSS EASTERN KANSAS AND NORTHWEST MISSOURI. AS A MATTER OF FACT...THE DISTANCE SPEED ANALYSIS ALONG WITH RUC ANALYSIS SUGGESTS THAT THE CURRENT DECK OF MVFR STRATUS WILL CLEAR THROUGH THE JOPLIN AIRPORT BY 8AM AND SPRINGFIELD AT 10AM. MAV GUIDANCE HOLDS ON TO THE STRATUS THROUGH THE INITIAL 6 HOUR FORECAST...BUT WILL FOLLOW THE RUC SUGGESTIONS DUE TO ONGOING SATELLITE TRENDS. VISIBILITIES HAVE BEEN WITHIN MVFR CONDITIONS THROUGH THE MORNING...HOWEVER THINK THAT VFR VISIBILITIES WILL UNFOLD THROUGH THE REST OF THE MORNING. AT TAF ISSUANCE TIME...SPRINGFIELD WAS UP TO 6SM AND JOPLIN WAS AT 8SM. PERHAPS THE MOST CHALLENGING ELEMENT TO PILOTS AND THE AVIATION COMMUNITY TODAY REGARDS STRONG / GUSTY NORTHWEST WINDS. THESE WINDS WILL REMAIN SUSTAINED AT OR AROUND 20 KNOTS...WITH GUSTS UP TO 30 KNOTS. BY THIS EVENING THE SURFACE PRESSURE GRADIENT RELAXES...AND SPEEDS WILL FOLLOW SUIT. A NORTHWEST DIRECTION WILL PERSIST INTO THIS EVENING. CRAMER && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 935 AM EST TUE FEB 26 2008 .SYNOPSIS... A STRONG COLD FRONT APPROACHING FROM THE WEST WILL CROSS THE EASTERN CAROLINAS LATE THIS AFTERNOON. COLD CANADIAN HIGH PRESSURE WILL BUILD IN WEDNESDAY AND THURSDAY BEFORE MOVING OFFSHORE ON FRIDAY. A HARD FREEZE IS POSSIBLE WEDNESDAY NIGHT. ANOTHER COLD FRONT WILL MOVE OFFSHORE EARLY ON SATURDAY...FOLLOWED BY HIGH PRESSURE ON SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 9 AM...COLD FRONT NOW SITTING ALONG THE APPALACHIANS IN EASTERN TENNESSEE/WESTERN NORTH CAROLINA. LINE OF CONVECTION...AT LEAST THE STRONGER SEGMENTS SEEM TO BE BREAKING UP INTO TWO DISTINCT CAMPS. THE NORTHERN PART...ALIGNED WITH A VORT MAX...MOVING RAPIDLY TO THE NORTHEAST AT 40 KNOTS...WHILE THE SOUTHERN AREA HAS A MORE EASTERLY COMPONENT ADVECTING TOWARD THE RICHER THETA-E AXIS TOWARD THE GULF OF MEXICO. THE RUC HAS A GOOD HANDLE ON THESE TRENDS. OVERALL FOR OUR AREA...NOT MUCH HAS CHANGED...THE SEVERE THREAT REMAINS THE SAME WITH A HIGH SHEAR/LOW CAPE EVENT UNFOLDING. SPC NOW HAS THE ENTER AREA IN A SLIGHT RISK. MORE SPECIFICALLY...FOR OUR AREA IT ALL BOILS DOWN TO MOISTURE ADVECTION AT THE SURFACE. MCS TO THE SOUTH COULD LIMIT VALUES. DEBRIS CLOUDS COULD LIMIT HEATING AS WELL. HAVE ADJUSTED POPS TO REFLECT A LATE MORNING TO MID AFTERNOON TIMEFRAME FOR THE WESTERN AND EASTERN AREAS RESPECTIVELY. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM THIS MORNING...COLD ADVECTION AT THE BEGINNING OF THE PERIOD WILL INCREASE IN STRENGTH THROUGH THE DAY HOLDING TEMPS IN THE UPPER 40S TO LOW 50S. BY 00Z GFS/ECMWF/NAM ALL HAVE 850 TEMPS BETWEEN -8 AND -10 AND SUB 530 1000-500 MB THICKNESS. STRONG COLD ADVECTION AND PARTLY SUNNY SKIES WILL RESULT IN WINDY CONDITIONS DURING THE DAY ON WED AS GOOD MIXING BRINGS MOST OF THE 20 TO 25 KT WINDS ALOFT TO THE SFC. COLD NIGHT ON TAP WED NIGHT WITH 850 TEMPS DROPPING BELOW -10 AND THICKNESS VALUES AT OR BELOW 520. THESE VALUES WOULD NORMALLY SUGGEST LOWS IN THE TEENS BUT ANTICIPATE GOOD BOUNDARY LAYER MIXING WITH SFC GRADIENT REMAINING TIGHT AND COLD ADVECTION CONTINUING THROUGH THE NIGHT. NOTORIOUS COLD SPOTS MAY DROP TO NEAR 20...BUT MOST AREAS WILL BE IN THE MID TO UPPER 20S. SFC RIDGE AXIS MOVES OVER THE AREA THU BEFORE SHIFTING N AND E THU NIGHT. ARCTIC AIR MASS REMAINS IN PLACE WITH HIGHS ON THU SIMILAR TO BUT SLIGHTLY COOLER THAN WED...EVEN WITH FULL SUN. DO NOT REALLY SEE ANY RETURN FLOW BEFORE THE PERIOD ENDS...BUT THU NIGHT WILL PROBABLY NOT END UP BEING AS COLD AS PREVIOUSLY THOUGHT. WARM FRONT EXTENDING S THROUGH THE WRN GREAT LAKES WILL BRUSH THE AREA THU NIGHT SPREADING MID AND UPPER LEVEL MOISTURE/CLOUD COVER OVER THE REGION. SFC COLD POOL REMAINS IN PLACE WITH VERY LITTLE EROSION...BUT LACK OF STRONG RADIATIONAL COOLING WILL LIMIT LOWS TO UPPER 20S TO AROUND 30 VS UPPER TEENS TO LOW 20S. && .LONG TERM /FRIDAY THROUGH MONDAY/... AS OF 3 AM THIS MORNING...HIGH PRESSURE SHIFTS NE OF THE REGION FRI WITH RETURN FLOW DEVELOPING. MID/UPPER LEVEL MOISTURE/CLOUD AND LOW LEVEL COLD AIR WILL KEEP HIGHS ON FRI A FEW DEGREES BELOW CLIMO. THINK GUIDANCE MAY BE TO QUICK TO WARM UP TEMPS AS SHALLOW COLD AIR TENDS TO LINGER LONGER THAN GUIDANCE EXPECTS. WENT UNDER GUIDANCE FOR FRI BUT MAY NOT BE COOL ENOUGH. EVEN 850 TEMPS FRI AFTN REMAIN BELOW 0. COLD FRONT DROPS IN FROM THE N FRI NIGHT INTO SAT CROSSING THE CAROLINA AROUND 12Z. NOT VERY ENTHUSIASTIC ABOUT PRECIP CHANCES WITH BEST DYNAMICS PASSING WELL TO THE N AND LIMITED MOISTURE ABOVE 700 MB. DID NOT MAKE ANY CHANGES TO INHERITED SILENT POPS. NOT MUCH CHANGE IN 850 TEMPS AND THICKNESS BEHIND THE FRONT...BUT CLEARING SKIES WILL RESULT IN WARMER TEMPS SAT AND SUN WITH READINGS ABOVE CLIMO. FAVORED THE ECMWF SOLUTION LATE IN THE PERIOD WHICH IS SLOWER THAN THE 00Z GFS WITH THE NEXT SYSTEM MOVING INTO THE TN VALLEY ON MON. CONDITIONS WILL REMAIN DRY THROUGH THE END OF THE PERIOD WITH TEMPS ABOVE CLIMO. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... NOT A LOT OF CHANGES TO THE PREVIOUS SET OF TAFS. TRIED TO NARROW THE TIMING OF CONVECTION...BASED ON A NICE LINE OF OMEGA BARRELING EAST AHEAD OF THE FRONT. IN THE NEAR TERM...SOUTHERLY WINDS ALOFT ARE MOVING TO THE SURFACE...WITH VISIBILITIES IMPROVING TO UNRESTRICTED SHORTLY AFTER 12Z. GUSTY SOUTHWEST WINDS WILL INCREASE TOWARDS MIDDAY AS LOW LEVEL JET SETS UP. GFS MODEL NOT AS ENTHUSIASTIC AS NAM IN REGARDS TO CONVECTION...BUT WILL LEAN TOWARD THE NAM GIVEN THE MODERATE INSTABILITY BY AFTERNOON AND HIGH SHEAR. FRONT BLOWS OFF THE COAST BY 00Z...WITH CONDITIONS BEHIND THE FRONT IMPROVING RAPIDLY. WINDS WILL VEER TO THE WEST SOUTHWEST...BUT REMAIN STRONG FOR A GOOD PORTION OF THE EVENING. VFR 00Z THROUGH THE END OF THE FORECAST PERIOD WITH DIMINISHING WINDS AFTER MIDNIGHT. NO AVIATION CONCERNS WEDNESDAY THROUGH FRIDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 9 AM...WINDS STILL A LITTLE SLOW TO GET CRANKING THIS MORNING ACROSS THE WATERS. LATEST SURFACE ANALYSIS SHOWS A RATHER SMALL/WEAK PRESSURE GRADIENT JUST OVER THE WATERS. THIS SHOULD TIGHTEN UP SHORTLY AND WILL SEE A RAPID INCREASE IN WINDS. TRENDS LOOK GOOD AND OBSERVATIONS SHOULD CATCH UP WITH FORECAST. NO CHANGES. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 AM THIS MORNING...SFC GRADIENT REMAINS TIGHT THROUGH WED AND INTO WED NIGHT WITH HIGH PRESSURE BUILDING IN FROM THE W. COMBINATION OF GRADIENT AND STRONG COLD ADVECTION WILL RESULT IN WIND SPEEDS AT OR ABOVE SCA THRESHOLDS FOR MUCH OF WED. OFFSHORE COMPONENT WILL HELP KEEP SEAS 6 FT OR LESS...THOUGH OUT NEAR 20 NM SLIGHTLY HIGH SEAS MAY BE ENCOUNTERED. WINDS BEGIN TO DECREASE EARLY THU AS CENTER OF HIGH SHIFTS OVER THE WATERS AND THEN NE OF THE WATERS THROUGH THU AND THU NIGHT. WEAK GRADIENT WILL KEEP WIND DIRECTION TUE AFTN/NIGHT HIGHLY VARIABLE...BUT WIND SPEEDS WILL GENERALLY BE 10 KT OR LESS WITH SEAS 2 TO 4 FT. LONG TERM /FRIDAY THROUGH SATURDAY/... AS OF 3 AM THIS MORNING...SRLY FLOW ON FRI WILL GRADUALLY INCREASE DURING LATE FRI AND FRI NIGHT AS COLD FRONT DROPS IN FROM THE NW...PINCHING THE GRADIENT. SPEEDS MAY APPROACH 20 KT LATE FRI INTO SAT BUT DURATION MAY NOT BE LONG ENOUGH TO PUSH SEAS ABOVE SCA THRESHOLDS. OFFSHORE FLOW DEVELOPS SAT AS COLD FRONT PUSHES OFFSHORE AND NEXT SFC HIGH BUILDS IN FROM THE NW. LITTLE TO NO COLD ADVECTION BEHIND THE FRONT AND GRADIENT REMAINS FAIRLY LAX WITH SPEEDS 15 KT OR LESS AND SEAS 3 TO 5 FT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 7 PM EST WEDNESDAY FOR AMZ250-252-254-256. && $$ SYNOPSIS...SHK NEAR TERM...SHK SHORT TERM...III LONG TERM...III AVIATION...DL nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 1005 AM CST TUE FEB 26 2008 .DISCUSSION... 15Z SURFACE ANALYSIS AND VAD WINDS STILL SUPPORT A WINDY DAY ACROSS THE FORECAST AREA. HIGH PRESSURE OVER THE PANHANDLE CREATING A 12MB SFC PRESSURE GRADIENT DOWN TO GULF COAST...WINDS OVER KHGX AOA 30 KNOTS AT 2K FT. SE TX PRESSURE GRADIENT WILL STAY TAUNT THROUGH THE DAY WITH AFTERNOON WARMTH BRINGING DOWN THOSE NEAR 30 KNOT NORTHERLIES. LCH/CRP RAOBS DEPICT A MODERATELY STRONG POST-FROPA DRY CAP UNDER THIS MORNING`S SOUTHEASTERN CWA`S STRATO CU DECK...UPSTREAM DEW POINTS IN THE LOW TO MID 20S. 12Z NAM12/GFS40 MODELING SIGNIFICANT BOUNDARY LAYER DRYING SO...WITH THE AFOREMENTIONED INITIAL CONDITIONS...FEEL AS IF THIS AFTERNOON WILL MAINLY BE SPENT IN THE MID TO UPPER 50S. TONIGHT WILL BE THE COOLEST NIGHT WE HAVE EXPERIENCED IN NEARLY A MONTH...12Z SUB-FREEZING TEMPS NORTH AND ALONG A BRENHAM TO CONROE TO LIVINGSTON LINE. THE 40 F ISOTHERM WILL NEARLY REACH THE COAST LINE. 31 && .PREV DISCUSSION... /ISSUED 402 AM CST TUE FEB 26 2008/ DISCUSSION... COLD FRONT ENTERING NEARSHORE WATERS EARLY THIS MORNING. RUC...NAM12 AND GFS INDICATE QUITE STRONG WINDS SURFACE TO 850 MB LAYER BEHIND FRONT. ALSO...PRESSURE GRADIENT BEHIND FRONT ALREADY TIGHTENING. WE WILL ISSUE A WIND ADVISORY FOR CWFA FOR TODAY INDICATING 20-25 MPH INLAND AREAS AND 25-30 MPH NEAR THE COAST. LINGERING CONVECTION NOTED EAST CENTRAL PORTION OF CWFA DUE TO REGION BEING UNDER RR QUAD OF UPPER JET CORE AND ENOUGH MOISTURE MID LEVELS. THIS HOWEVER IS EXPECTED TO MOVE OUT OF REGION BEFORE SUNRISE. WE WILL MENTION ISOLATED SHOWERS FOR THAT PORTION FOR EARLY MORNING PERIOD ONLY (FOR ZFPHGX). PW VALUES DROPPING OVER REGION AS PER GOES SOUNDER LOOP. NORTHWEST PORTION OF CWFA APPROACHING HALF AN INCH BUT STILL MOIST SOUTHEAST REGION PROBABLY NEAR AN INCH. STRONG COLD AIR ADVECTION WILL DROP TEMPERATURES TO THE 30S LATER TONIGHT INLAND AREAS WITH READINGS NEAR OR SLIGHTLY BELOW FREEZING FAR NORTHERN ZONES. HIGH PRESSURE CENTER WILL SETTLE OVER FAR SOUTH TEXAS TOWARD WEDNESDAY MORNING WITH WINDS ACROSS OUR CWFA DECREASING QUITE A BIT ACROSS CENTRAL AND NORTHERN SECTIONS. UPPER FLOW BECOMING MORE ZONAL THURSDAY WITH RETURN FLOW AT LOWER LEVELS DUE TO HIGH SHIFTING TO SOUTHEAST CONUS. LOWER LEVEL MOISTURE WILL INCREASE DURING THE LATTER PART OF THIS WEEKDAY WITH SUSTAINED ONSHORE FLOW. WE SHALL SEE A WARM UP THURSDAY AND INTO THE WEEKEND ALONG WITH INCREASING HUMIDITY VALUES. WE DID CONTINUE TO MENTION SLIGHT CHANCE POPS END OF WEEK AND CHANCE (30 PERCENT) WEEKEND. VERTICAL PROFILES WOULD INDICATE POSSIBLE THUNDERSTORMS DURING THE WEEKEND. GFS SHOWING DEVELOPING UPPER LOW OVER NORTHWEST OLD MEXICO BY FRIDAY WITH UPPER FLOW OVER TEXAS BECOMING MORE SOUTHWESTERLY. REINFORCING HIGH PRESSURE AT THE SURFACE WILL MOVE TO THE EASTERLY PORTION OF CONUS SATURDAY MAKING THE FLOW ACROSS THE NORTH CENTRAL AND NORTHEAST GULF MORE EASTERLY. GFS INDICATE UPPER LOW OVER OLD MEXICO WILL WEAKEN...OPEN UP AND MOVE EAST LATE IN THE WEEKEND WHILE A DEVELOPING LARGE UPPER TROUGH IS INDICATED ..EXTENDING FROM THE GREAT LAKES TO THE WESTERN HIGH PLAINS. THIS SYSTEM WILL USHER A STRONG COLD FRONT TO OUR REGION MONDAY. 37 AVIATION... SOME SHRA HAVE DEVELOPED GENERALLY FROM THE CONROE-HUNTSVILLE AREA AND THEN OFF TO THE EAST AND NORTHEAST INTO LOUISIANA. EXPECT THIS STUFF TO MOVE OFF TO THE EAST SOME TIME BEFORE OR RIGHT AROUND SUNRISE. LOOKS LIKE A GOOD PORTION OF THE AREA (ESPECIALLY UP NORTH) WILL SEE A BKN DECK OF MID AND HIGH LEVEL CLOUDS THIS MORNING. ALL CLOUDS SHOULD DISSIPATE OR MOVE ON OUT SOME TIME LATE THIS AFTERNOON. STRONG NORTH WINDS WILL BE THE MAIN AVIATION CONCERN TODAY. EXPECT SUSTAINED 20 TO 25 KNOT WINDS INLAND AND 20 TO 30 KNOT WINDS ALONG THE COAST. WE`LL LIKELY SEE SOME HIGHER GUSTS. GRADIENT RELAXES SIGNIFICANTLY LATE THIS AFTERNOON INLAND AND LATE THIS EVENING ALONG THE COAST. SKC TONIGHT. 42 MARINE... WILL HAVE SMALL CRAFT ADVISORIES IN EFFECT FOR THE BAYS THROUGH 6 PM AND FOR THE GULF WATERS THROUGH MIDNIGHT FOR STRONG NORTH WINDS INCREASING TO 20 TO 30 KNOTS. HAVE TODAY`S SEAS INCREASING TO 5 TO 7 FEET NEARSHORE AND 7 TO 10 FEET OFFSHORE. BOTH WINDS AND SEAS WILL RELAX TONIGHT AS THE GRADIENT WEAKENS WITH SURFACE HIGH PRESSURE BUILDING INTO THE AREA...BUT WE`LL PROBABLY NEED SOME KIND OF CAUTION OR ADVISORY FLAGS EVEN AFTER MIDNIGHT FOR PORTIONS OF OUR GULF WATERS. WINDS WILL SWING AROUND TO THE EAST AND SOUTHEAST WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT. CAUTION AND/OR ADVISORY FLAGS WILL BE POSSIBLE AGAIN ON THURSDAY AS THIS ONSHORE FLOW STRENGTHENS. 42 FIRE WEATHER... WILL DROP THE FIRE WEATHER WATCH FOR TODAY. ALTHOUGH WINDS WILL BE STRONG AND THE GROUND REMAINS DRY...RELATIVE HUMIDITY VALUES THIS AFTERNOON ARE NOT ANTICIPATED TO FALL INTO A 20% TO 25% RANGE. 42 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 58 32 63 42 71 / 10 0 0 0 0 HOUSTON (IAH) 61 35 61 42 70 / 10 0 0 0 0 GALVESTON (GLS) 62 43 59 48 67 / 10 0 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...WIND ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: AUSTIN...BRAZORIA...BRAZOS...BURLESON...CHAMBERS... COLORADO...FORT BEND...GALVESTON...GRIMES...HARRIS... HOUSTON...JACKSON...LIBERTY...MADISON...MATAGORDA... MONTGOMERY...POLK...SAN JACINTO...TRINITY...WALKER... WALLER...WASHINGTON...WHARTON. GM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY. SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. && $$ DISCUSSION...31 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 1238 PM EST TUE FEB 26 2008 .SYNOPSIS... A COLD FRONT WILL MOVE THROUGH THE FORECAST AREA THIS AFTERNOON. DRYING WILL OCCUR BEHIND THE FRONT. IT WILL BE BREEZY BEHIND THE FRONT THROUGH WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A BAND OF SHOWERS AHEAD OF THE COLD FRONT WAS IN THE EAST PART OF THE FORECAST AREA EARLY THIS AFTERNOON. THE SHOWERS SHOULD MOVE EAST OF THE REGION DURING THE MIDDLE OF THE AFTERNOON. WINDS JUST UPSTREAM SUPPORT THE LAKE WIND ADVISORY. SATELLITE AND THE LATEST RUC INDICATE AT LEAST SOME UPPER-LEVEL CLOUDINESS CONTINUING DURING THE REST OF THE AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... SKIES WILL BECOME MOSTLY CLEAR TONIGHT. WINDS WILL STAY UP A BIT OVERNIGHT...EVEN MORE SO OVER THE AREA LAKES SO WILL KEEP LWA IN EFFECT. PRESSURE GRADIENT SLOW TO RELAX SO WITH DAYTIME HEATING ON WEDNESDAY EXPECT SFC WINDS TO BE CLOSE TO LWA CRITERIA SO WILL KEEP LWA IN EFFECT UNTIL 00Z THURSDAY. DRY HIGH PRESSURE CENTERED IN THE SOUTHERN PLAINS WILL BUILD INTO THE AREA WEDNESDAY AND THURSDAY. WITH STRONG CAA EXPECT TEMPS TO STRUGGLE INTO THE LOWER TO MIDDLE 50S BOTH WEDNESDAY AND THURSDAY. OVERNIGHT LOWS MAY FALL INTO THE MIDDLE TO UPPER 20S AS PER MODEL CONSENSUS. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... TEMPERATURES MODERATE INTO THE LATTER PART OF THE WEEK AS HIGH PRESSURE MOVES OFFSHORE. WEAK COLD FRONT DROPS SOUTHEASTWARD FRIDAY NIGHT INTO SATURDAY BUT MOISTURE LOOKS RATHER LIMITED. WILL KEEP MENTION OF SLIGHT CHANCE POPS FOR FRIDAY NIGHT. DRY WEATHER THROUGH THE WEEKEND WITH MAX TEMPERATURES RANGING FROM THE MIDDLE 60S TO NEAR 70 DEGREES BY SUNDAY. A COLD FRONT APPROACHES FROM THE WEST ON MONDAY SO WILL GO WITH CHANCE POPS AT THAT TIME. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... SATELLITE AND RADAR TRENDS SUPPORT SHOWERS AND LOW CLOUDINESS SHIFTING EAST OF THE TERMINALS DURING THE EARLY AFTERNOON. EXPECT ENOUGH DRYING AND MIXING FOR VFR BEGINNING AROUND 20Z. IT WILL BE BREEZY. USED THE LAMP GUIDANCE FOR THE WIND FORECAST. NO SIGNIFICANT IMPACTS EXPECTED DURING THE EXTENDED PERIOD. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...LAKE WIND ADVISORY UNTIL 7 PM EST WEDNESDAY FOR SCZ015-016-018- 020>022-025>031-035>038-041. GA...LAKE WIND ADVISORY UNTIL 7 PM EST WEDNESDAY FOR GAZ040-063>065- 077. && $$ SYNOPSIS...JL NEAR TERM...JL AVIATION...JL ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1128 AM CST TUE FEB 26 2008 .AVIATION... 18Z TAFS...HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE CENTRAL PLAINS THIS AFTERNOON...AND WINDS WILL GRADUALLY WEAKEN THROUGH THE AFTERNOON HOURS. SOME MVFR CEILINGS CAN BE EXPECTED UNTIL MID- AFTERNOON...OTHERWISE VFR CONDITIONS WILL PREVAIL. SCHRECK && .PREV DISCUSSION... /ISSUED 636 AM CST TUE FEB 26 2008/ UPDATE... MADE SOME TWEAKS TO GOING GRIDS TO MATCH CURRENT OBS...TRENDS AND CONSISTENCY. UPDATED GRIDS WILL BE OUT SHORTLY. -HOWERTON AVIATION... FAIRLY SIGNIFICANT CONCERN IS MVFR CLOUDS ACROSS MUCH OF NEBRASKA. OPERATIONAL MODELS ARE EITHER CLUELESS OR SERIOUSLY STRUGGLING WITH THIS LOW LEVEL MOISTURE. RUC SORT OF HINTED AT IT AND THE GLOBAL FORECAST SYSTEM MODEL BUFR SOUNDING VALID AT 1500 UTC AT KRSL SORT OF HINTED AT IT AS WELL. MM5 SEEMED TO HAVE THE BEST HANDLE WITH MUCH LOWER RELATIVE HUMIDITY MOVING ACROSS EASTERN KS AT THIS TIME AND HIGHER RELATIVE HUMIDITY MOVING OUT OF NEBRASKA. IT SHOWS THE MOISTURE IN NEBRASKA ADVECTING ACROSS NE KS WITH GRAZING SHOT AT KSLN. OPTED TO NOT CUT IT THAT CLOSE AND INCLUDE TEMPO GROUP AT KRSL AS WELL GIVEN CURRENT SATELLITE TREND. OTHERWISE WITH HIGH PRESSURE BUILDING ACROSS THE AREA...WINDS SHOULD GRADUALLY DIMINISH THROUGHOUT THE DAY AND BECOME LIGHT AND VARIABLE BY TONIGHT. -HOWERTON PREV DISCUSSION... /ISSUED 251 AM CST TUE FEB 26 2008/ DISCUSSION... SYNOPSIS: A DISCERNIBLE 500-MB SHORTWAVE...MOVING S/SE OVER ERN ND @ 12 MIDNIGHT WILL RACE S/SE OVER THE GREAT PLAINS TODAY...CROSSING THE KS/MO BORDER ~12 NOON...THEN THE LWR MS VALLEY ~6PM THIS EVENING. THIS FEATURE WILL OPERATE IN TANDEM WITH AN ULTRA-HIGH AMPLITUDE MID-UPR RIDGE POSITIONED ALONG THE WEST COAST TO INDUCE A FAST NW FLOW REGIME THAT PREVAILS THRU EARLY THU MORNING. AT THAT TIME A 2ND 500-MB SHORTWAVE WILL RIDE E OVER THE PACIFIC COAST UPR RIDGE TO INDUCE DEAMPLIFICATION LATE WED NIGHT. THE 500-MB SHORTWAVE THEN SPRINTS SE ACROSS THE NRN ROCKIES...INDUCING SFC-700MB TROFFING ALONG THE FRONT RANGE THU MORNING. THE RESULT WILL BE A WARMING TREND THAT`LL OCCUR WED & THU BEFORE A COLD FRONT OF PACIFIC ORIGIN SWEEPS SE THROUGH THE AREA THU NIGHT. TODAY: INTENSE LOW PRESSURE...CENTERED OVER MID-MS VALLEY EARLY THIS MORNING...WILL CONTINUE TO MOVE E TOWARD THE APPALACHIANS ALLOWING SKIES TO CLEAR IN GENERAL W-E MANNER OVER THE KICT CWFA. HOWEVER...NLY SFC-850MB FLOW REMAINS QUITE STRONG THRU MID-AFTERNOON...SO BRISK N/NW WINDS TO PERSIST THRU LATE AFTERNOON. MOREOVER THE LACKING OF A DOWNSLOPE COMPONENT WILL KEEP PREVENT SIGNIFICANT WARMING...SO HAVE HELD MAXES TO ~40F WITH SE KS ON COOLER SIDE OF FENCE. TONIGHT: A VERY WEAK SFC TROF DRIFTS E ACROSS NRN PLAINS TO INDUCE LWR-DECK FLOW TO BACK TO A LIGHT WLY COMP. WITH DRY AIRMASS IN PLACE KEPT MINS INTACT WITH LWR 20S ASSIGNED TO ALL AREAS. WED-THU: WARMING TREND SLATED ALL AREAS FOR REASONS STATED IN "SYNOPSIS" HOWEVER EASED UP ON "DEGREE" OF WARMUP ON THU AS 500-MB SHORTWAVE WILL SPREAD CONSIDERABLE CIRROSTRATUS SE ACROSS KS. AS SUCH LOWERED MAXES ALL AREAS TO MID/UPR 50S WITH NE CORRIDOR ON COOLER END OF THIS THERMAL SPECTRUM. THU NIGHT: STRENGTHENING 500-MB SHORTWAVE SURGING E/SE ACROSS FAR NRN PLAINS WILL SWEEP A WEAK PACIFIC COLD FRONT SE ACROSS KS. AIRMASS DRY...SO FRONTAL PASSAGE TO INDUCE NO MORE THAN A WIND SHIFT. DUE TO COLD FRONT`S LATE ARRIVAL...HAVE RAISED MINS ACROSS SC & SE KS TO 35-40F. THIS WEEKEND: FAST ZONAL FLOW PREVAILS FOR MOST OF PERIOD & WITH DEEP SW/WLY FLOW OVER THE PLAINS...SAT TO BE WARMEST DAY OF THE WEEK WITH HIGHS FLIRTING WITH 70F ALONG WRN CORRIDOR. LATE SAT NIGHT/EARLY SUNDAY MORNING A STRONGER & DEEPENING POSITIVELY-TILTED UPR-DECK TROF SPRINTS E/SE ACROSS NRN & C PLAINS THAT`LL FORCE FAIRLY POTENT COLD FRONT SE ACROSS THE KICT CWFA LATE SAT NIGHT. CONVERGENCE ALONG THE BOUNDARY APPEARS SUFFICIENT TO INTRO ~20% -SHRA TO SE KS LATE SAT NIGHT. WITH UPR-DECK TROF CONTINUING TO DEEPEN ON SUNDAY...HAVE INTRODUCED EMBEDDED TSRA TO ALL AREAS ON SUN. && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 41 23 53 31 / 0 0 0 0 HUTCHINSON 40 22 53 29 / 0 0 0 0 NEWTON 39 22 52 29 / 0 0 0 0 ELDORADO 39 22 51 29 / 0 0 0 0 WINFIELD-KWLD 42 24 53 31 / 0 0 0 0 RUSSELL 41 22 53 27 / 0 0 0 0 GREAT BEND 41 23 54 29 / 0 0 0 0 SALINA 41 23 51 28 / 0 0 0 0 MCPHERSON 40 23 52 28 / 0 0 0 0 COFFEYVILLE 40 22 53 30 / 0 0 0 0 CHANUTE 38 21 51 28 / 0 0 0 0 IOLA 37 21 51 28 / 0 0 0 0 PARSONS-KPPF 39 21 52 29 / 0 0 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DULUTH MN 1030 AM CST TUE FEB 26 2008 .UPDATE...EXPANDED SCATTERED POPS ACROSS NORTHWEST WISCONSIN FOR TODAY...WITH SNOW SHOWERS DEVELOPING UNDERNEATH UPPER TROUGH. THE FEW LES SHOWERS REMAIN LIGHT ATTM...BUT WILL MAINTAIN LIKELY POPS ALONG THE SOUTH SHORE WITH COLD POOL ALOFT STILL WORKING ITS WAYS ACROSS WESTERN LAKE SUPERIOR THIS LATE MORNING. ELSEWHERE...SNOW SHOWERS OR FLURRIES WILL CONTINUE AS LAPSE RATES STEEPEN WITH SFC HEATING AND LOW LEVEL CAA. && .PREV DISCUSSION... /ISSUED 321 AM CST TUE FEB 26 2008/ DISCUSSION... QUIET WEATHER CONTINUES THIS MORNING AS FORCING MECHANISMS ARE WEAK... OR NON EXISTENT. SFC PATTERN REFLECTS CWA IN GRADIENT BETWEEN DEPARTING OHIO VALLEY SFC LOW AND HIGH PRESSURE OVER WRN HIGH PLAINS. AN AMPLIFYING MID LVL TROF...WITH A POCKET OF -35C AT 50H...IS PUSHING INTO THE NWRN CWA THIS MORNING. FLURRIES ARE BEING SQUEEZED OUT OF THE MOISTENING COLUMN AS LAPSE RATES STEEPEN TEMPORARILY. THIS SCENARIO WILL SPREAD SE TODAY ACROSS CWA WITH NO ACCUMULATIONS EXPECTED. BOTH LATEST RUC AND GFS HINT AT A SECONDARY SHORTWAVE MIGRATING SOUTH TODAY ACROSS ERN CWA WITH PERHAPS SOME ADDITIONAL FLURRIES POSSIBLE. STILL HAVE SOME POTENTIAL FOR LES OVER ERN WI ZONES HOWEVER SUMMATION OF LES PARAMETERS INDICATES SIGNIFICANT ACCUMULATIONS NOT LIKELY. EXPECT SOME DEVELOPMENT EARLY THIS MORNING AS MID LVL FEATURE WILL ENHANCE THERMAL/MOISTURE PROPERTIES OF SYNOPTIC BACKGROUND. HOWEVER...OVERALL FETCH NOT VERY FAVORABLE AS 85H TRAJECTORY MAINTAINS TOO MUCH NW VS NRLY FLOW. THERE MAY BE JUST TOO MUCH ICE COVER ON SUPERIOR TO ALLOW ENOUGH MSTR FLUX INTO BL AIR. EVEN NORMALLY EXCITABLE HI RES 4KM NMM SIMULATED REFLECTIVITY PRODUCT NOT SUGGESTING ORGANIZED EVENT. BUFKIT PROFILES...BOTH GFS/NAM...RATHER MEAGER WITH PRODUCTION OF LAKE INDUCED CAPE/EQ LEVEL AS INVERSION HEIGHTS REMAIN NEAR 4/5K. LES POTENTIAL SHOULD GRADUALLY DECREASE BY WEDNESDAY AFTERNOON AS INSTABILITY LESSENS AND DEEP LAYER OF DRYING MOVES IN. EXTENDED...THUR THROUGH SUNDAY... MEAN MID LVL RIDGE REMAINS OVER WRN CONUS WITH SEVERAL SHORTWAVES AMPLIFYING OVER CWA. FIRST ONE OCCURS THUR/FRI. MDL CONSENSUS IS FAIRLY GOOD THIS FAR OUT WITH REGARD TO OVERALL FCST OF SNOWFALL SPREADING EAST THURSDAY. MDL TIMING VARIES FROM FASTEST..ECMWF..TO SLOWER NAM/GFS/CMC...WITH UKM IN BETWEEN. BOTH EC/GFS SUGGEST THAT PROGRESSIVE NATURE OF MID LVL FLOW BY FRIDAY WILL KEEP SYSTEM MOVING EAST... LIMITING SIGNIFICANT SNOWFALL. OF COURSE...WITH THIS LACKLUSTER SNOW SEASON AS OF LATE....2 INCHES MIGHT SEEM SIGNIFICANT TO SOME. ANOTHER CHANCE OF SNOW SAT/SUN WITH AMPLIFYING SHORTWAVE. EC/GFS HAVE SOME TIMING DIFFERENCES BOTH BOTH FOCUS BEST CHANCE OF ACCUMULATION OVER FAR NRN CWA. AVIATION... CONTINUED COLD AIR ADVECTION TODAY...AS WELL AS A SHORTWAVE...WILL LEAD TO MVFR OR LOW VFR CEILINGS TODAY. AREAS OF LIGHT SNOW OR FLURRIES ARE ALSO POSSIBLE...AND MAY REDUCE VSBYS TO 3 TO 5 MILES IN SPOTS DURING THE DAY. SNOW SHOWERS MAY BE A BIT HEAVIER ALONG PORTIONS OF THE SOUTH SHORE OF LAKE SUPERIOR...ESPECIALLY EAST OF KASX...TOWARD KIWD. && POINT TEMPS/POPS... DLH 22 4 19 3 / 20 10 10 10 INL 17 0 18 -3 / 20 10 10 20 BRD 26 6 23 7 / 20 10 10 20 HYR 26 3 21 -3 / 30 10 10 10 ASX 24 7 19 3 / 50 20 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. $$ LILES mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 243 PM CST TUE FEB 26 2008 .DISCUSSION... SHORT TERM...TONIGHT THROUGH FRIDAY MAIN CONCERNS THROUGH THIS PERIOD ARE THE CHANCE FOR PCPN FROM LATE WEDNESDAY NIGHT INTO THURSDAY AND TEMPERATURES. WATER VAPOR LOOP AND UPPER AIR CHARTS FROM 12Z THIS MORNING INDICATED A MID TROPOSPHERIC TROUGH FROM THE GREAT LAKES REGION INTO TEXAS...A RIDGE OVER THE WESTERN U.S. INTO WESTERN CANADA...AND MORE COMPLEX TROUGHING OVER THE PACIFIC BETWEEN 130 W AND 150 W. STRONG SYSTEM CENTERED NEAR 37 N 138 W WAS IMPRESSIVE. IT APPEARS THAT THIS MAY BE THE FEATURE THAT THE 12Z GFS MODEL BRINGS THROUGH THE LOCAL AREA LATE THURSDAY. MORE ON THAT LATER. SURFACE ANALYSIS AT 20Z SHOWED HIGH PRESSURE EXTENDING FROM TEXAS NORTHWARD INTO THE DAKOTAS. PRESSURE GRADIENT IN OUR AREA HAS BEEN DECREASING THE PAST SEVERAL HOURS. SATELLITE LOOP STILL SHOWED A CONSIDERABLE AMOUNT OF STRATOCUMULUS OVER THE AREA...BUT IT WAS MOVING EASTWARD AND STARTING TO BECOME BROKEN RATHER THAN OVERCAST IN SOME AREAS. THIS TREND SHOULD CONTINUE INTO THE EVENING HOURS. SOME FLURRIES COULD STILL FALL FROM THESE CLOUDS THIS EVENING. SURFACE RIDGE WILL BUILD OVER THE AREA TONIGHT...AND SHIFT EAST OF THE AREA BY LATE WEDNESDAY. WENT WITH LOWS GENERALLY COLDER THAN BOTH THE GFS AND ETA MOS GUIDANCE...BASED ON DECREASING CLOUDINESS AND LIGHT WINDS. MOS DID NOT SEEM TO BAD ON WEDNESDAY...SINCE MORE SUNSHINE IS EXPECTED. MOST SPOTS SHOULD HIT 35 TO 40...WITH MUCH OF SOUTHEAST NEBRASKA IN THE LOWER OR MID 40S. WEDNESDAY NIGHT IS NOT EXPECTED TO BE AS COLD WITH SOUTHERLY LOW LEVEL RETURN FLOW BETTER ESTABLISHED BY THEN AND TREND FOR THICKENING CLOUDINESS. DID MENTION A SLIGHT CHANCE FOR SLEET OR FREEZING RAIN IN THE NORTH WHERE MODELS INDICATED A DECENT COMBINATION OF MOISTURE AND LIFT. PCPN TYPE WAS BASED ON BUFKIT FORECAST SOUNDINGS. ANY PCPN BETWEEN 12Z AND 18Z THURSDAY COULD BE RAIN OR SNOW...BUT THEN JUST RAIN BY AFTERNOON. DECIDED TO INCREASE POPS TO AROUND 30 PERCENT IN THE SOUTHERN ZONES BASED ON TWO AREAS OF UPWARD VERTICAL MOTION FORECAST BY THE 12Z GFS. FIRST WAS CENTERED AROUND 18Z THURSDAY IN THE 600 MB TO 300 MB LAYER. THE SECOND WAS MORE BETWEEN 850 MB AND 700 MB CLOSER TO 00Z FRIDAY. THIS COULD BE ASSOCIATED WITH THE FEATURE THAT WAS OUT OVER THE PACIFIC THIS AFTERNOON. CHANCE FOR PCPN THURSDAY NIGHT AND FRIDAY SEEMED MINIMAL. TEMPERATURES BOTH THURSDAY AND FRIDAY SHOULD TOP OUT IN THE 40S MOST AREAS. LONG TERM...FRIDAY NIGHT THROUGH TUESDAY HIGHLIGHTS IN THE EXTENDED PERIODS CONSIST OF TRANSITION FROM RELATIVELY WARM CONDITIONS DAYS 4/5...TO A COOL DOWN DAY 6 WITH POSSIBLE PCPN...THEN MODEST TEMP REBOUND DAY 7. UPPER SHORT WAVE TROF MOVING THROUGH THE PACIFIC NORTHWEST FRIDAY NIGHT KICKS THE WESTERN CONUS RIDGE INTO THE PLAINS BY SATURDAY MORNING. UPPER TROF ENERGY SEPARATES WITH THE NORTHERN BRANCH FLOWING ACROSS THE U.S./CANADIAN BORDER...WHILE THE SOUTHERN PIECE SINKS INTO THE CENTRAL GREAT BASIN. EASTWARD MIGRATING NORTHERN TROF SPINS UP SURFACE LOW IN ALBERTA BY 12Z SAT WITH ASSOCIATED WARM FRONT EXTENDING SOUTHWARD FROM EASTERN MT TO IA. WILL KEEP SATURDAY DRY THOUGH AS MODELS INDICATE BULK OF GULF MOISTURE REMAINS IN THE SOUTHERN PLAINS UNTIL AFTERNOON. HAVE NOTED THE GFS 12Z RUN HAS SIGNIFICANTLY SLOWED MOISTURE RETURN TO THE PLAINS COMPARED TO THE 06Z RUN. NEVERTHELESS...PCPN CHANCES LOOK REASONABLE STARTING EARLY SUNDAY MORNING WHEN THE NEXT COLD FRONT DROPS OUT OF THE DAKOTAS AND INTO THE PLAINS. APPEARS FROM CRITICAL THKNS/850 TEMP PROGS THAT PCPN TYPE SHOULD BE RAIN EARLY ON WITH A TRANSITION TO RAIN/SNOW MAINLY OVER THE NORTHERN CWA IN THE AFTERNOON. FROPA THROUGH THE CWA SHOULD BE COMPLETE LATE AFTERNOON...WITH POSSIBLE POST-FRONTAL PCPN SUNDAY NIGHT OVER THE SOUTHERN CWA VIA UPPER DEFORMATION ZONE. DRY AND A BIT WARMER THEN ON DAY 7. && .AVIATION... FOR TAF SITES KOMA...KLNK AND KOFK. AN AREA OF STRATUS/STRATOCUMULUS WITH FLURRIES MOVED INTO THE FCST AREA THIS MORNING AND SHOULD CONTINUE THROUGH THE EARLY EVENING HOURS. FOR NOW...HAVE THE TRANSITION FROM STRATUS TO HIGHER CLDS FM 00Z TO 03Z. THERE ARE SOME HINTS FROM THE NEW RUC THAT THESE LOW CLDS MAY HANG ON LONGER...SO THIS WILL NEED TO BE MONITORED. SFC HIGH PRES WILL BUILD IN ALLOWING WINDS TO DECREASE TO LIGHT AND VARIABLE. AN APPROACHING SHORTWAVE TROF IN NORTHWEST FLOW WILL BRING SOME HIGHER CLOUDS TO THE REGION OVERNIGHT...WITH SOME LOWER AND MID CLOUDS POSSIBLE MONDAY MORNING AND INTO MONDAY AFTERNOON. DEPENDING ON THE CLOUD COVER...THERE MAY BE SOME PATCHY FOG WITH VSBYS 3-5SM FM AROUND 13 TO 15Z. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...MILLER LONG TERM...DEE AVIATION...ZAPOTOCNY ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 1120 AM CST TUE FEB 26 2008 .AVIATION... A FEW CIRRUS CLOUDS EARLY THIS AFTERNOON OTHERWISE VFR. WINDS ARE EXPECTED TO DECOUPLE INLAND BETWEEN 01-04Z. 43 .DISCUSSION... 15Z SURFACE ANALYSIS AND VAD WINDS STILL SUPPORT A WINDY DAY ACROSS THE FORECAST AREA. HIGH PRESSURE OVER THE PANHANDLE CREATING A 12MB SFC PRESSURE GRADIENT DOWN TO GULF COAST...WINDS OVER KHGX AOA 30 KNOTS AT 2K FT. SE TX PRESSURE GRADIENT WILL STAY TAUNT THROUGH THE DAY WITH AFTERNOON WARMTH BRINGING DOWN THOSE NEAR 30 KNOT NORTHERLIES. LCH/CRP RAOBS DEPICT A MODERATELY STRONG POST-FROPA DRY CAP UNDER THIS MORNING`S SOUTHEASTERN CWA`S STRATO CU DECK...UPSTREAM DEW POINTS IN THE LOW TO MID 20S. 12Z NAM12/GFS40 MODELING SIGNIFICANT BOUNDARY LAYER DRYING SO...WITH THE AFOREMENTIONED INITIAL CONDITIONS...FEEL AS IF THIS AFTERNOON WILL MAINLY BE SPENT IN THE MID TO UPPER 50S. TONIGHT WILL BE THE COOLEST NIGHT WE HAVE EXPERIENCED IN NEARLY A MONTH...12Z SUB-FREEZING TEMPS NORTH AND ALONG A BRENHAM TO CONROE TO LIVINGSTON LINE. THE 40 F ISOTHERM WILL NEARLY REACH THE COAST LINE. 31 && .PREV DISCUSSION... /ISSUED 402 AM CST TUE FEB 26 2008/ DISCUSSION... COLD FRONT ENTERING NEARSHORE WATERS EARLY THIS MORNING. RUC...NAM12 AND GFS INDICATE QUITE STRONG WINDS SURFACE TO 850 MB LAYER BEHIND FRONT. ALSO...PRESSURE GRADIENT BEHIND FRONT ALREADY TIGHTENING. WE WILL ISSUE A WIND ADVISORY FOR CWFA FOR TODAY INDICATING 20-25 MPH INLAND AREAS AND 25-30 MPH NEAR THE COAST. LINGERING CONVECTION NOTED EAST CENTRAL PORTION OF CWFA DUE TO REGION BEING UNDER RR QUAD OF UPPER JET CORE AND ENOUGH MOISTURE MID LEVELS. THIS HOWEVER IS EXPECTED TO MOVE OUT OF REGION BEFORE SUNRISE. WE WILL MENTION ISOLATED SHOWERS FOR THAT PORTION FOR EARLY MORNING PERIOD ONLY (FOR ZFPHGX). PW VALUES DROPPING OVER REGION AS PER GOES SOUNDER LOOP. NORTHWEST PORTION OF CWFA APPROACHING HALF AN INCH BUT STILL MOIST SOUTHEAST REGION PROBABLY NEAR AN INCH. STRONG COLD AIR ADVECTION WILL DROP TEMPERATURES TO THE 30S LATER TONIGHT INLAND AREAS WITH READINGS NEAR OR SLIGHTLY BELOW FREEZING FAR NORTHERN ZONES. HIGH PRESSURE CENTER WILL SETTLE OVER FAR SOUTH TEXAS TOWARD WEDNESDAY MORNING WITH WINDS ACROSS OUR CWFA DECREASING QUITE A BIT ACROSS CENTRAL AND NORTHERN SECTIONS. UPPER FLOW BECOMING MORE ZONAL THURSDAY WITH RETURN FLOW AT LOWER LEVELS DUE TO HIGH SHIFTING TO SOUTHEAST CONUS. LOWER LEVEL MOISTURE WILL INCREASE DURING THE LATTER PART OF THIS WEEKDAY WITH SUSTAINED ONSHORE FLOW. WE SHALL SEE A WARM UP THURSDAY AND INTO THE WEEKEND ALONG WITH INCREASING HUMIDITY VALUES. WE DID CONTINUE TO MENTION SLIGHT CHANCE POPS END OF WEEK AND CHANCE (30 PERCENT) WEEKEND. VERTICAL PROFILES WOULD INDICATE POSSIBLE THUNDERSTORMS DURING THE WEEKEND. GFS SHOWING DEVELOPING UPPER LOW OVER NORTHWEST OLD MEXICO BY FRIDAY WITH UPPER FLOW OVER TEXAS BECOMING MORE SOUTHWESTERLY. REINFORCING HIGH PRESSURE AT THE SURFACE WILL MOVE TO THE EASTERLY PORTION OF CONUS SATURDAY MAKING THE FLOW ACROSS THE NORTH CENTRAL AND NORTHEAST GULF MORE EASTERLY. GFS INDICATE UPPER LOW OVER OLD MEXICO WILL WEAKEN...OPEN UP AND MOVE EAST LATE IN THE WEEKEND WHILE A DEVELOPING LARGE UPPER TROUGH IS INDICATED ..EXTENDING FROM THE GREAT LAKES TO THE WESTERN HIGH PLAINS. THIS SYSTEM WILL USHER A STRONG COLD FRONT TO OUR REGION MONDAY. 37 AVIATION... SOME SHRA HAVE DEVELOPED GENERALLY FROM THE CONROE-HUNTSVILLE AREA AND THEN OFF TO THE EAST AND NORTHEAST INTO LOUISIANA. EXPECT THIS STUFF TO MOVE OFF TO THE EAST SOME TIME BEFORE OR RIGHT AROUND SUNRISE. LOOKS LIKE A GOOD PORTION OF THE AREA (ESPECIALLY UP NORTH) WILL SEE A BKN DECK OF MID AND HIGH LEVEL CLOUDS THIS MORNING. ALL CLOUDS SHOULD DISSIPATE OR MOVE ON OUT SOME TIME LATE THIS AFTERNOON. STRONG NORTH WINDS WILL BE THE MAIN AVIATION CONCERN TODAY. EXPECT SUSTAINED 20 TO 25 KNOT WINDS INLAND AND 20 TO 30 KNOT WINDS ALONG THE COAST. WE`LL LIKELY SEE SOME HIGHER GUSTS. GRADIENT RELAXES SIGNIFICANTLY LATE THIS AFTERNOON INLAND AND LATE THIS EVENING ALONG THE COAST. SKC TONIGHT. 42 MARINE... WILL HAVE SMALL CRAFT ADVISORIES IN EFFECT FOR THE BAYS THROUGH 6 PM AND FOR THE GULF WATERS THROUGH MIDNIGHT FOR STRONG NORTH WINDS INCREASING TO 20 TO 30 KNOTS. HAVE TODAY`S SEAS INCREASING TO 5 TO 7 FEET NEARSHORE AND 7 TO 10 FEET OFFSHORE. BOTH WINDS AND SEAS WILL RELAX TONIGHT AS THE GRADIENT WEAKENS WITH SURFACE HIGH PRESSURE BUILDING INTO THE AREA...BUT WE`LL PROBABLY NEED SOME KIND OF CAUTION OR ADVISORY FLAGS EVEN AFTER MIDNIGHT FOR PORTIONS OF OUR GULF WATERS. WINDS WILL SWING AROUND TO THE EAST AND SOUTHEAST WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT. CAUTION AND/OR ADVISORY FLAGS WILL BE POSSIBLE AGAIN ON THURSDAY AS THIS ONSHORE FLOW STRENGTHENS. 42 FIRE WEATHER... WILL DROP THE FIRE WEATHER WATCH FOR TODAY. ALTHOUGH WINDS WILL BE STRONG AND THE GROUND REMAINS DRY...RELATIVE HUMIDITY VALUES THIS AFTERNOON ARE NOT ANTICIPATED TO FALL INTO A 20% TO 25% RANGE. 42 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 58 32 63 42 71 / 10 0 0 0 0 HOUSTON (IAH) 61 35 61 42 70 / 10 0 0 0 0 GALVESTON (GLS) 62 43 59 48 67 / 10 0 0 0 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...WIND ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: AUSTIN...BRAZORIA...BRAZOS...BURLESON...CHAMBERS... COLORADO...FORT BEND...GALVESTON...GRIMES...HARRIS... HOUSTON...JACKSON...LIBERTY...MADISON...MATAGORDA... MONTGOMERY...POLK...SAN JACINTO...TRINITY...WALKER... WALLER...WASHINGTON...WHARTON. GM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR THE FOLLOWING ZONES: GALVESTON BAY...MATAGORDA BAY. SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. && $$ DISCUSSION...31 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 301 PM CST TUE FEB 26 2008 .SHORT TERM...THROUGH FRIDAY NIGHT FOCUS TODAY WAS ADDING DETAIL TO YET ANOTHER ACCUMULATING SNOW EVENT HEADED FOR THE AREA THURS AFTN/EVENING...AND RATHER INSIGNIFICANT CLOUD/TEMPERATURE TRENDS TONIGHT/WED. CURRENTLY...GOES 11-3.9 MICRON CHANNEL SHOWING TWO LARGE STRATUS FIELDS IN COLD ADVECTION/NORTHERLY FLOW. ONE OVER MUCH OF WISCONSIN...THE OTHER OVER MUCH OF SRN/WRN MN...AND THIS ONE HAS MANY FLURRIES. A RELATIVE MINIMUM IN CLOUD COVER RIGHT DOWN THE MS RIVER VALLEY THROUGH THE ARX FORECAST AREA. TEMPERATURES MOVING LITTLE TODAY...WITH READINGS STILL IN THE 20S...WELL BELOW NORMAL. STEEP LAPSE RATES IN RUC/LAPS SOUNDINGS OWING TO THE GUSTY WINDS/MIXING WITH LOW DEWPOINTS /SINGLE DIGITS/ OVER THE AREA. TONIGHT THROUGH WEDNESDAY NIGHT...QUIET WEATHER WITH CLOUDS/TEMPERATURES THE FOCUS. WITH MUCH OF THE STRATUS CURRENTLY EAST OF THE RIDGE AXIS WHICH IS OVER THE DAKOTAS CURRENTLY...HAVE CONCERNS THAT MAY SEE REMNANTS OF THIS STRATUS FIELD WELL INTO WEDNESDAY WITH CONTINUED FLURRIES...ESPECIALLY DOWNWIND OF SUPERIOR OVER NCNTL WISCONSIN. A COUPLE MORE WEAK WAVES TONIGHT/WED WILL ENHANCE WEAK LIFT/CYCLONIC FLOW BEFORE THINGS BREAK OUT FOR GOOD WED NIGHT. TEMPERATURES TONIGHT VERY TRICKY GIVEN POCKETS OF CLEARING. WITH LOW DEWPOINTS...ANYONE THAT CLEARS SUBSTANTIALLY AFTER MIDNIGHT WILL BOTTOM OUT BELOW GOING FORECAST. BUT GIVEN THE AMOUNT OF CLOUDS ON SATELLITE IMAGES...HARD TO GO TOO LOW ON MIN TEMPS. WEDNESDAY VERY SIMILAR...IN TERMS OF THERMAL STRUCTURE AND LOWER LEVEL LAPSE RATE. MIX OF CLOUDS/SUN AND FLURRIES WILL BE THE RULE...WITH WELL BELOW NORMAL TEMPS. SHOULD SEE MORE CLEARING WED NIGHT WITH A BETTER DROP ON TEMPERATURES...AGAIN WELL BELOW NORMAL. STRONG SHORTWAVE TROUGH TO DIG SOUTHEAST AND AMPLIFY INTO THE LONGWAVE TROUGH POSITION ON THURSDAY/THURSDAY NIGHT WILL BRING IMPACTING WEATHER TO FORECAST AREA...WITH ACCUMULATING SNOW A SOLID BET. OUTSTANDING AGREEMENT IN NUMEROUS RUNS OF GFS/GEFS/SREF/NAM/ECMWF...THIS HAS BEEN ADVERTISED FOR SEVERAL DAYS NOW...SO TOOK POPS CATEGORICAL. 285-295K LAYER SHOWS STRONG ISENTROPIC ASCENT IN RESPONSE TO THE APPROACHING SHORTWAVE WITH A NOTICEABLE MOISTURE TRANSPORT SIGNAL IN THIS DATA...RIGHT INTO THE FORECAST AREA. 26.12Z GFS SHOWING TWO CENTERS OF MID/UPPER LEVEL Q/G FORCING WHICH WILL BOTH FOCUS ON FORECAST AREA...AND THERE HAS BEEN GOOD EVIDENCE IN PROBABILITIES ON QPF IN THE SREFS/GEFS THAT AREAS EAST OF THE MS RIVER STAND THE BEST CHANCE AT THE HIGHEST SNOW TOTALS. THE ENTIRE SYSTEM WILL BECOME MORE ORGANIZED OFF TO THE EAST AS IT DEEPENS...SO THIS MAKES SENSE TO SEE HIGHER TOTALS EAST. REGARDLESS...A STRONG SIGNAL FOR 2 INCH SNOW ACCUMULATIONS IN MOST AREAS WITH 4-6 HRS OF STRONG ASCENT AND MODERATE SNOW. WILL LIKELY SEE A NARROWER STRIPE OF 3-4 INCH SNOWS WHERE LIFT DURATION IS LONGER /EAST OF RIVER/...BUT THAT LEVEL OF DETAIL WILL COME IN FUTURE SHIFTS. GOOD THING...A TRANSIENT SYSTEM...AS MENTIONED ABOVE AS IT WILL SNOW AT A GOOD CLIP AS IT MOVES THROUGH. SNOW RATIOS START OUT HIGH...BUT WILL DECREASE ON THE BACK EDGE OF THE SNOW SHIELD AS STRONG WARM ADVECTION DECREASES RATIOS. TEMPERATURES FALL LITTLE WITH THE STRONG WARM ADVECTION...AND THEN MOVE LITTLE ON FRIDAY AS COLD ADVECTION INCREASES WITH GUSTY WINDS AND CLEARING SKIES. .LONG TERM...SATURDAY THROUGH TUESDAY BETTER THAN AVERAGE AGREEMENT IN THIS PERIOD THAT IT WILL BE UNSETTLED/ACTIVE WITH A POTENTIALLY LARGE MOISTURE LADEN STORM MOVING THROUGH THE CENTRAL CONUS SUNDAY/MONDAY. MILD /NEAR NORMAL/ FOR THE WEEKEND WHICH SHOULD GO INTO MELTING A FEW INCHES OFF THE DEEP SNOWPACK OVER THE AREA. STRONG RIDGING ALOFT ON SATURDAY WITH DEEP SOUTHERLY LOW LEVEL FLOW WILL ALLOW THIS WARMING. MAY BE DEALING WITH FOG/STRATUS DURING SATURDAY NIGHT BEFORE WARM ADVECTION/ISENTROPIC LIFT BECOME STRONG ENOUGH TO ALLOW AREAS OF RAIN TO BREAK OUT AS NRN STREAM ENERGY SHIFTS EAST ACROSS SOUTHERN CANADA...DRIVING SFC COLD FRONT THROUGH ON SUNDAY/SUNDAY NIGHT. NEED TO WATCH STRONG SRN STREAM ENERGY LAGGING BACK WHICH MAY INDUCE DEEP CYCLONE ALONG THE TRAILING BOUNDARY LATE IN THE WEEKEND...AND WHAT WILL BECOME A VERY WET SYSTEM ESPECIALLY SOUTH. IF NRN STREAM CAN PUSH THROUGH FAST ENOUGH...BRINGING IN COLDER AIR...WILL NEED TO WATCH POTENTIAL FOR ACCUMULATING SNOW SUNDAY OR EVEN INTO MONDAY IF A DEEP ENOUGH SFC LOW CAN DEVELOP. SOME SUBTLE HINTS AT THIS IN THE ENSEMBLE MEMBERS /GEFS/ AND NEW 26.12Z ECMWF. LOOKS LIKE EARLY NEXT WEEK WILL COME OUT BELOW NORMAL AGAIN IN TEMPS AS LARGE ERN PACIFIC RIDGE ALLOWS TROUGHING AND NEGATIVE HEIGHT/TEMP ANOMALIES IN THE CENTRAL CONUS. && .AVIATION... MVFR CLOUD DECK //1-3KFT// SINKING SOUTHEAST ACROSS THE REGION...ASSOCIATED WITH SATURATED LOW LAYERS AND A 500 MB SHORTWAVE. THERE IS A BREAK AHEAD OF THIS DECK THOUGH...BASICALLY RUNNING ALONG THE MISSISSIPPI RIVER. RH FIELDS WOULD SUGGEST THAT THIS PARTLY CLOUDY AREA MAY HOLD THROUGH MUCH OF TONIGHT. SOME FLURRIES/-SN ALSO ASSOCIATED WITH THIS LOW CLOUD DECK...THANKS TO GOOD LAPSE RATES IN THE 1000-850 MB LAYER. GENERALLY NO VSBY RESTRICTION WITH THE LIGHT SNOW...ALTHOUGH SOME BRIEF PERIODS OF 4SM WILL BE POSSIBLE THROUGH ABOUT 03Z. AFTER THAT...EXPECT THE SNOW TO MOVE EAST OF THE TAF SITES. CLOUDS TONIGHT ARE PROBLEMATIC...WITH THAT MVFR DECK JUST WEST OF THE RIVER...AND SCATTERED CONDITIONS TO THE EAST. MOISTURE REMAINS TRAPPED BELOW AN INVERSION...PER THE BUFKIT SOUNDINGS...AND THE SFC RIDGE AXIS DOES NOT WORK INTO THE REGION UNTIL WED AFTERNOON. THIS WILL HOLD BACK ON CLEARING OF THE LOW CLOUDS UNTIL LATER WED MORNING...ALTHOUGH THERE ARE HINTS THAT THE LOW DECK MAY NOT ADVANCE AS FAR EAST AS PREVIOUS THOUGH. CONFIDENCE IS NOT HIGH ON THE CLOUDS TRENDS AT THE MOMENT...BUT WILL STAY WITH A MORE CLOUDY TREND THROUGHOUT TONIGHT FOR BOTH KRST AND KLSE. THIS MAY HAVE TO BE ADJUSTED FOR MORE SCT CLOUDS FOR KLSE TONIGHT...AND THE BREAKUP OF THE MVFR DECK MAY HAVE TO BE EXTENDED UNTIL LATE WED MORNING. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM...BINAU AVIATION...RIECK wi