AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 849 PM EDT MON MAY 19 2003 .UPDATE...THE UPPER LOW CONTINUES TO WEAKEN AS IT DRIFTS SWD TOWARD THE CENTRAL GULF THIS EVENING. A STATIONARY FRONTAL BOUNDARY EXTENDS FROM SE GA WNW INTO AL. RADAR INDICATES ISOLATED THUNDERSTORMS ALONG THIS ZONE OF CONVERGENCE IN AL. PERSISTENT RAINS N OF THE VLD AREA ARE GRADUALLY DIMINISHING. WITH THE LOSS OF DAYTIME HEATING AND WARMING TEMPS AT MID LEVELS IN THE WAKE OF THE DEPARTING UPPER LOW, INSTABILITY WILL CONTINUE TO DECREASE THROUGH THE EVENING. WILL LOWER POPS IN THE EVENING UPDATE, BUT KEEP A 10-20 POP UNTIL MIDNIGHT OR SO. THE MARINE FORECAST LOOKS PRETTY MUCH ON TRACK. .PREVIOUS DISCUSSION...LATEST WATER VAPOR IMAGERY/RUC H5 COMPOSITE SHOWS CLOSED UPPER LOW ALONG THE MS GULF COAST CONTINUING ITS SLOW SWD DRIFT. SEVERAL VORT MAXIMA ROTATING AROUND LOW...W/ ONE OFF THE PANHANDLE COAST RESPONSIBLE FOR SCATTERED CONVECTION. OUTFLOW BOUNDARY FROM THIS CONVECTION MOVED INTO THE FL BIG BEND/FAR SW GA. INTERACTION W/ THIS BOUNDARY & THE GULF SEA BREEZE CONTINUES TO SPARK ADDITIONAL SHWRS/TSTMS. IT APPEARS BEST THREAT FOR ANY STRONG TSTMS THIS AFTN WILL BE OVER S/CNTRL GA & ERN BIG BEND WHICH HAVE SEEN MORE INSOLATION...W/ CAPES OF 2000+ J/KG & LI'S FROM -4 TO -6. 12Z MODELS IN GOOD AGREEMENT W/ CONTINUED SWD PROGRESSION AND WEAKENING OF UPPER LOW INTO THE CENTRAL GULF OF MEXICO DURING THE NEXT 12 TO 36 HRS. MEANWHILE...UPPER RIDGE OVER THE ERN CONUS GETS SUPPRESSED AS S/WAVE TROUGH SKIRTS ACROSS THE NRN TIER U.S. SURFACE HIGH WEDGES SWD ALONG THE ATLANTIC COAST WHICH WILL INCREASE THE LOW-LEVEL E-SELY FLOW THRU WED. PWAT VALUES CONTINUE TO EDGE UPWARD TO NEAR 2" ON WED. COLD FRONT APPROACHING THE MS VALLEY TONIGHT WILL MOVE THRU THE OH/TN VALLEYS EARLY WED....AND INTO NRN GA/AL WED AFTN. SURFACE WAVE FORMS ALONG BOUNDARY OVER AL...WHICH WILL SLOW ITS SEWD PROGRESS. GFS IS TRENDING A BIT FASTER W/ FRONTAL MOTION THAN ETA/NGM. PERIOD OF MAX LIFT/DYNAMICS LOOKS LIKE IT WILL OCCUR BETWEEN 18Z WED & 06Z THU. DECENT INSTABILITY...AMPLE GULF/ATLANTIC MOISTURE & SEA BREEZES WILL KEEP SCATTERED MAINLY AFTERNOON/EVENING SHWRS/TSTMS THRU TUE NIGHT. HAVE INCREASED POPS TO LIKELY ALL BUT SE BIG BEND FOR WED. PCPN ENDS W/ FROPA FROM NW TO SE ON THU. PORTIONS OF ERN PANHANDLE RECEIVED 3-5" OF RAIN EARLIER TODAY. ATTM... DURATION/AREAL COVERAGE OF HEAVY RAINFALL SHOULD BE LIMITED TO PRECLUDE A FLOOD WATCH. MODEL BASIN-AVERAGED QPF VALUES DURING THE NEXT 48 HRS SHOULD RANGE FROM 0.5 TO 1" W/ ISOLATED 1-2" AMOUNTS POSSIBLE. .MARINE...NO HIGHLIGHTS OR CHANGES TO SHORT TERM FORECAST. SELY WINDS BELOW 15 KTS & SEAS 4 FT OR LESS THRU 48 HRS. WINDS VEER TO SW-W ON WED AHEAD OF COLD FRONT...THEN BECOME NW-N ON THU AFTER FROPA. .FIRE WEATHER...NO REQUIREMENTS. .EXTENDED (FRI-MON)...UPCOMING MEMORIAL DAY WEEKEND STILL LOOKING SEASONABLY WARM & DRY AS SURFACE HIGH PRESSURE BUILDS INTO THE AREA FROM THE NW PER GFS. .PRELIMINARY POINT TEMPS/POPS... TLH 69 86 69 85 / 40 50 40 60 PFN 72 84 72 83 / 40 50 40 60 DHN 69 83 69 82 / 40 50 50 60 ABY 68 84 67 83 / 40 50 40 60 VLD 68 86 67 85 / 40 50 40 60 CTY 69 87 68 86 / 30 50 30 50 .TLH WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. $$ MAJ/MAW fl EAST CENTRAL FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 328 PM EDT MON MAY 19 2003 CURRENTLY... EAST COAST SEA BREEZE HELPING TO PRODUCE SCATTERED THUNDERSTORMS OVER THE INTERIOR MAINLY WEST OF INTERSTATE 95. AN OUTFLOW BOUNDARY MOMENTARILY INCREASED BUOY 009/S WINDS TO 15 TO 20 KNOTS BUT...THE WINDS SHOULD SETTLE BACK TO 10 TO 15 KNOTS ONCE THE EFFECT OF THE BOUNDARY PUSHING THROUGH WEARS OFF. CUTOFF LOW OVER LA/MS SLOWLY MOVING SOUTH ACROSS THE MS DELTA AND INTO THE NORTH GULF OF MEXICO WHILE HIGH PRESSURE OVER NEW ENGLAND/MID ATLANTIC STATES CONTINUES TO RIDGE SOUTHWEST ALONG THE EASTERN SEABOARD...NORTH FLORIDA AND INTO THE NORTHEAST GULF OF MEXICO. TONIGHT...WATER VAPOR LOOP SHOWS DRIER AIR WRAPPING AROUND THE SOUTHEAST QUADRANT OF THE CUTOFF LOW OVER LA/MS AND MOVING TOWARD THE CENTRAL FLORIDA PENINSULA. THE COMBINATION OF MID LEVEL DRIER AIR AND 500MB RIDGING OVER THE AREA APPEARS TO BE INHIBITING CONVECTION TO A DEGREE AND THE RUC FORECAST AT 20/03Z STILL HAS 500MB RIDGING OVER THE PENINSULA. CURRENT 20/30 COASTAL/INTERIOR SPLIT OF STORMS LOOKS GOOD BUT WILL CONTINUE THEM LONGER INTO THE NIGHT AS THE RIDGING OVER THE PENINSULA WEAKENS. TUESDAY AND WEDNESDAY...CUTOFF OVER THE NORTH GULF OF MEXICO CONTINUES TO FILL AS IT SLOWLY MOVES SOUTH WILL THE RIDGE AXIS REMAIN TO OUR NORTH. EXPECT EASTERLY WINDS TO PERSIST AND INCREASE TO 10 TO 15 MPH ALONG THE COAST AS THE SEA BREEZE ESTABLISHES ITSELF IN THE AFTERNOON. SCATTERED THUNDERSTORMS/SHOWERS WILL BE THE RULE AGAIN AS THE SEA BREEZE PUSHES INLAND. THURSDAY THROUGH SATURDAY...THE GFS AND OTHER LONGER TERM MODELS STILL WANT TO DEVELOP A LOW OVER THE SOUTHEAST STATES AND MOVE ACROSS NORTH FLORIDA THEN ALONG THE EAST COAST OVER THE WEEKEND. IF THIS VERIFIES EXPECT A PERIOD OF SOUTHWEST TO WEST WINDS AND TEMPERATURES A COUPLE OF DEGREES ABOVE GUIDANCE/CLIMO DUE TO THE SOUTHWEST TO WEST FLOW ACROSS THE LAND MASS. SUNDAY AND MEMORIAL DAY/MONDAY...AS THE LOW PRESSURE WORKS IT WAY ALONG THE EAST COAST HIGH PRESSURE BUILDS ACROSS THE SOUTHEAST AND GULF OF MEXICO AND EVENTUALLY MERGING WITH HIGH PRESSURE OVER THE BAHAMAS. WITH THE RIDGE AXIS AND CENTER OF HIGH PRESSURE TO OUR NORTH WE SHOULD BE IN A NORTH TO NORTHEAST FLOW BY MONDAY. MARINE...AGAIN WITH HIGH PRESSURE TO THE NORTH...EASTERLY WINDS WILL PERSIST THROUGH WEDNESDAY. THE EASTERLY WINDS WILL ALSO MAINTAIN THE CURRENT 4 TO 5 FOOT LONG PERIOD SWELL MOVING ACROSS THE COASTAL WATERS. ON THURSDAY THE WINDS VEER TO THE SOUTH AS LOW PRESSURE DEVELOPS OVER THE SOUTHEAST STATES AND MOVES EAST NORTHEAST. FRIDAY THE WINDS SHIFT TO THE SOUTHWEST AND WEST AS A WEAK COLD FRONT IS FORECAST TO MOVE OVER FLORIDA. PRELIMINARY CCF... DAB BB 072/084 069/084 071 2313 MCO BB 072/088 069/088 072 3442 MLB BB 073/086 071/086 073 2313 .MLB...NONE. PUBLIC/MARINE...WIMMER AVIATION/FIRE...SHARP $$ fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 155 PM EDT MON MAY 19 2003 CURRENTLY: LATEST WATER VAPOR IMAGERY/RUC H5 COMPOSITE SHOWS CLOSED UPPER LOW ALONG THE MS GULF COAST CONTINUING ITS SLOW SWD DRIFT. SEVERAL VORT MAXIMA ROTATING AROUND LOW...W/ ONE OFF THE PANHANDLE COAST RESPONSIBLE FOR SCATTERED CONVECTION. OUTFLOW BOUNDARY FROM THIS CONVECTION MOVED INTO THE FL BIG BEND/FAR SW GA. INTERACTION W/ THIS BOUNDARY & THE GULF SEA BREEZE CONTINUES TO SPARK ADDITIONAL SHWRS/TSTMS. IT APPEARS BEST THREAT FOR ANY STRONG TSTMS THIS AFTN WILL BE OVER S/CNTRL GA & ERN BIG BEND WHICH HAVE SEEN MORE INSOLATION...W/ CAPES OF 2000+ J/KG & LI'S FROM -4 TO -6. MODELS/FORECAST: 12Z MODELS IN GOOD AGREEMENT W/ CONTINUED SWD PROGRESSION & WEAKENING OF UPPER LOW INTO THE CENTRAL GULF OF MEXICO DURING THE NEXT 12 TO 36 HRS. MEANWHILE...UPPER RIDGE OVER THE ERN CONUS GETS SUPPRESSED AS S/WAVE TROUGH SKIRTS ACROSS THE NRN TIER U.S. SURFACE HIGH WEDGES SWD ALONG THE ATLANTIC COAST WHICH WILL INCREASE THE LOW-LEVEL E-SELY FLOW THRU WED. PWAT VALUES CONTINUE TO EDGE UPWARD TO NEAR 2" ON WED. COLD FRONT APPROACHING THE MS VALLEY TONIGHT WILL MOVE THRU THE OH/TN VALLEYS EARLY WED....AND INTO NRN GA/AL WED AFTN. SURFACE WAVE FORMS ALONG BOUNDARY OVER AL...WHICH WILL SLOW ITS SEWD PROGRESS. GFS IS TRENDING A BIT FASTER W/ FRONTAL MOTION THAN ETA/NGM. PERIOD OF MAX LIFT/DYNAMICS LOOKS LIKE IT WILL OCCUR BETWEEN 18Z WED & 06Z THU. DECENT INSTABILITY...AMPLE GULF/ATLANTIC MOISTURE & SEA BREEZES WILL KEEP SCATTERED MAINLY AFTERNOON/EVENING SHWRS/TSTMS THRU TUE NIGHT. HAVE INCREASED POPS TO LIKELY ALL BUT SE BIG BEND FOR WED. PCPN ENDS W/ FROPA FROM NW TO SE ON THU. PORTIONS OF ERN PANHANDLE RECEIVED 3-5" OF RAIN EARLIER TODAY. ATTM...DURATION/AREAL COVERAGE OF HEAVY RAINFALL SHOULD BE LIMITED TO PRECLUDE A FLOOD WATCH. MODEL BASIN-AVERAGED QPF VALUES DURING THE NEXT 48 HRS SHOULD RANGE FROM 0.5 TO 1" W/ ISOLATED 1-2" AMOUNTS POSSIBLE. MARINE: NO HIGHLIGHTS OR CHANGES TO SHORT TERM. SELY WINDS BELOW 15 KTS & SEAS 4 FT OR LESS THRU 48 HRS. WINDS VEER TO SW-W ON WED AHEAD OF COLD FRONT...THEN BECOME NW-N ON THU AFTER FROPA. FIRE WEATHER: NO REQUIREMENTS. EXTENDED (FRI-MON): UPCOMING MEMORIAL DAY WEEKEND STILL LOOKING SEASONABLY WARM & DRY AS SURFACE HIGH PRESSURE BUILDS INTO THE AREA FROM THE NW PER GFS. .PRELIMINARY POINT TEMPS/POPS... TLH 69 86 69 85 / 40 50 40 60 PFN 72 84 72 83 / 40 50 40 60 DHN 69 83 69 82 / 40 50 50 60 ABY 68 84 67 83 / 40 50 40 60 VLD 68 86 67 85 / 40 50 40 60 CTY 69 87 68 86 / 30 50 30 50 .TLH WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. $$ MAJ fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 210 PM CDT MON MAY 19 2003 PUBLIC FORECAST DISCUSSION FOR PM ZONES/GRIDS... SHOWERS POPPING UP ALL ACROSS CWA THIS AFTN WHILE MAIN ONSLAUGHT OF TSTMS STILL IN IA AND MO. TSTMS CROSSING MS RVR NEAR 7PM ALONG WITH COLD FRONT AND REACHING RFD ABT 9PM AND PAST CHI BY MDNGT. SHUD BE SOME RESIDUAL SHOWERS/OVC SKIES INTO MRNG HOURS TUESDAY...THEN CLRG IN AFTN AND ERY EVE. SHUD BE A CATEGORICAL EVENT WITH POPS NR 100%... DIMINISHING TO 60% IN MRNG. ETA STILL KEEPING HIGHS IN MID 50S TMRW WHILE AVN/NGM RECOVERING TMPS TO AROUND 60. WILL GO WITH THE LATTER CONSIDERING TIME OF YEAR AND ASSUMING SOME SUNSHINE BREAKS OUT IN AFTN. MAXES MAY BE LATE IN THE DAY. THIS OF COURSE APPLIES TO INLAND LOCATIONS AWAY FROM LAKE WHICH WUD LIKELY HAVE HIGHS ONLY IN MID 50S AT BEST. CLR SKIES TUE NGT AND RATHER SUNNY FOR WED AS HIGH BUILDING DOWN LAKE MICHIGAN. WNDS STILL OFF THE LAKE WED THRU SATURDAY. THUS NO 70S UNTIL THEN...AND THEN ONLY SOUTH OF I-80. BROAD UPR RIDGE SLIPPING ACROSS MIDWEST FRIDAY WITH JET DIVING SOUTH FROM UPR TO MID MS VLY. SOME SHOWERS PSBL WEST OF CWA BUT KEEPING IT SOMEWHAT CLDY BUT DRY UNTIL SUN NGT. AT THAT TIME THAT SAME UPR TROF DEEPENS OVER OH VLY AND STARTS RETROGRADING BACK TO SRN MICHIGAN WITH FURTHER DEEPENING SUNDAY...THEN TO CHI ON TUESDAY. WILL BRING SHOWERS IN SUNDAY NIGHT AND CONTINUE INTO MONDAY FOR CHI AREA/NW INDIANA. .CHI...NONE RLB AVIATION DISCUSSION FOR 18Z TAFS RADAR SHOWS SHOWERS DEVELOPING RAPIDLY IN WESTERN AND NORTH CENTRAL ILLINOIS. THE SHOWERS ARE DEVELOPING IN A DEFORMATION AREA SEEN ON THE PROFILER DATA AT 700 MB. THERE IS DESTABILIZATION OCCURRING AS WELL. THE LOW CLOUDS EXTEND FAR WEST INTO WESTERN IOWA AND MINNESOTA. THE RUC40 MODEL SHOWS THE CAPE INCREASING 2100 UTC TO 0000 UTC THIS EVENING OVER NORTH ILLINOIS. WITH THE SHOWERS DEVELOPING QUICKLY WILL MENTION SHOWERS IN THE THE TAFS FOR THIS LATE AFTERNOON AND EVENING...AFTER 23 UTC. THIS IS FOR ORD...MDW...DPA AND GYY. THE SHOWERS ARE CLOSE TO RFD. WILL FORECAST THE SHOWERS AFTER 20 UTC. THERE IS NO LIGHTNING WITH THESE SHOWERS. LIFTED INDEX FORECASTS SHOW THE RAPID INCREASE IN INSTABILITY FROM 21 UTC TO 03 UTC. WILL FORECAST THUNDERSTORMS FOR RFD AFTER 02 UTC FOR ALL THE TAFS. THIS FRONT WILL BE NARROW WITH A RAPID WIND SHIFT. WILL FORECAST NORTHWEST WINDS AFTER 06 UTC. WHW il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 1241 PM CDT MON MAY 19 2003 AVIATION DISCUSSION FOR 18Z TAFS RADAR SHOWS SHOWERS DEVELOPING RAPIDLY IN WESTERN AND NORTH CENTRAL ILLINOIS. THE SHOWERS ARE DEVELOPING IN A DEFORMATION AREA SEEN ON THE PROFILER DATA AT 700 MB. THERE IS DESTABILIZATION OCCURRING AS WELL. THE LOW CLOUDS EXTEND FAR WEST INTO WESTERN IOWA AND MINNESOTA. THE RUC40 MODEL SHOWS THE CAPE INCREASING 2100 UTC TO 0000 UTC THIS EVENING OVER NORTH ILLINOIS. WITH THE SHOWERS DEVELOPING QUICKLY WILL MENTION SHOWERS IN THE THE TAFS FOR THIS LATE AFTERNOON AND EVENING...AFTER 23 UTC. THIS IS FOR ORD...MDW...DPA AND GYY. THE SHOWERS ARE CLOSE TO RFD. WILL FORECAST THE SHOWERS AFTER 20 UTC. THERE IS NO LIGHTNING WITH THESE SHOWERS. LIFTED INDEX FORECASTS SHOW THE RAPID INCREASE IN INSTABILITY FROM 21 UTC TO 03 UTC. WILL FORECAST THUNDERSTORMS FOR RFD AFTER 02 UTC FOR ALL THE TAFS. THIS FRONT WILL BE NARROW WITH A RAPID WIND SHIFT. WILL FORECAST NORTHWEST WINDS AFTER 06 UTC. WHW PUBLIC FORECAST DISCUSSION FOR AM ZONES/GRIDS... NEXT SYSTEM ON TRACK THIS AM AS H5 TROUGH MOVES EAST ALONG CANADIAN BORDER ON NORTHERN PLAINS. AT THE SURFACE COLD FRONT EXTENDS FROM NEAR INL SOUTHWEST TO GLD WITH RW/TRW AHEAD OF FRONT. MODLES STILL IN AGREEMENT IN KEEPING CLOUD COVER IN AREA THROUGH TODAY AND THEN BRINGING PCPN INTO WESTERN PORTIONS OF FORECAST AREA AROUND 00Z. FROPA EXPECTED AROUND 06Z IN NORTHEAST IL WITH MAX UVV. SHOWERS AND THUNDERSTORMS SHOULD BEGIN DURING THE EVENING HOURS AND CONTINUE AFTER FROPA. POST FRONTAL PRECIP LINGERS THROUGH MID MORNING TUESDAY IN EASTERN PORTIONS. POST FRONTAL WINDS SHIFT RAPIDLY TO NORTH WITH SPEEDS INCREASING TO 20 MPH THROUGH MOST OF TUESDAY. TEMPS WILL DROP NOTICEBALY FROM TODAYS AS MAXS ONLY AROUND 60. BROAD SURFACE HIGH SITS OVER CENTRAL US/UPPER LAKES AND EEPS WINDS FROM NORTHEAST FOR REMAINDER OF THE FORECAST CYCLE. THIS WILL GENERALLY HOLD CHI TEMPS BLO SLOWLY WARMING TEMPS OVER REMAINDER OF AREA. BROAD TROUG DEVELOPS ALOFT WITH AXIS THROUGH THE CWA BY FRIDAY. AVN INDICATES WAVES ROTATING THROUGH WESTERN PORTION OF TROUGH BY 12Z FRIDAY BUT MOISTURE APPEARS IN SHORT SUPPLY SO WORST APPEARS TO BE SOME INCREASE IN CLOUDINESS BUT NO PRECIP. AFTER TONIGHT/TUESDAY AM THEN FORECAST IS FOR DRY WX. .CHI...NONE il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1100 AM EDT MON MAY 19 2003 FOG BURNING OFF NICELY EAST OF THE MOUNTAINS...WITH SOME WAY TO GO IN THE SHENANDOAH VALLEY AND NEAR THE MOUNTAINS. HAVE UPDATED THE ZONES TO WORD SKY CONDITION MOSTLY SUNNY FOR MOST AREAS. WILL SEE SOME SCT LOW CLOUDS AS FOG BURNS OFF WITH MIXING EARLY THIS AFTERNOON. RIGHT REAR QUAD OF 250 MB JET OVER MID ATLANTIC WILL ALSO PRODUCE SCATTERED CIRRUS...WITH SOME MID LEVEL CLOUDS ACROSS SOUTHWEST PORTION OF CWA WITH MOISTURE FROM MIDWEST SYSTEM RIDING AROUND MIDLEVEL RIDGE. HAVE ALSO BUMPED UP TEMPERATURES ACROSS MOST OF THE AREA BASED ON RUC CROSS SECTIONS GENERALLY SHOWING MIXING UP TO 850MB WITH TEMPERATURES WARMING TO 8-9C BY MID AFTERNOON. ROGOWSKI .LWX... DC...NONE. MD...NONE. VA...NONE WV...NONE. MARINE...NONE. md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 936 PM EDT MON MAY 19 2003 MAIN UPDATE CONCERNS ARE WINDS AND TIMING OF PCPN ACROSS FCST AREA. LATEST WV LOOP SHOWS A MID/UPR TROF MOVING INTO THE NRN PLAINS WITH A WELL-DEFINED SHRTWV MOVING INTO ERN MN. ASSOCIATED SFC COLD FRONT HAS MOVED INTO THE WRN U.P. AND WRN WI WITHIN PAST HR. RADAR LOOP INDICATES A SOLID BAND OF SHRA ACCOMPANYING FRONT...AS KIWD AWOS HAS RECEIVED 0.36 INCH IN PAST HR. LIGHTNING STRIKES ALONG AND AHEAD OF FRONT HAVE GENERALLY STAYED SOUTH OVR WI...WHERE RUC INDICATES MARGINAL INSTABILITY OF AROUND 100 J/KG CAPE AND LI'S AND SI'S ZERO OR NEGATIVE C. QPF VALUES OF 18Z ETA LINES UP WELL WITH RADAR PCPN RETURNS AT PRESENT SO WL USE ETA FOR TIMING STEADY PCPN INTO CNTRL COUNTIES AROUND MIDNIGHT AND THEN INTO ERN COUNTIES AROUND 06Z OR AFT. ETA AND RUC DEPICT THAT HEAVIEST PCPN WILL FALL WEST OF MQT-CRYSTAL FALLS LINE...WHERE BEST UPR DIV LOCATED IN RRQ OF 100 KT 250 MB JET MAX MOVG THRU WRN ONTARIO. UPR DYNAMICS AND LOW LEVEL CONVERGENCE WKNS AS FRONT MOVES INTO CNTRL AND ERN COUNTIES OVRNGT. GIVEN VERY LIMITED INSTABILITY...WL REMOVE MENTION OF THUNDER FROM ALL COUNTIES ON UPDATE. POST-FROSTAL WINDS NOT NEARLY AS STRONG NOW AS DIURNAL MIXING HAS SUBSIDED...ALTHOUGH STILL HAVE FAIRLY TIGHT GRAD BTWN SFC LOW AND CDFNT OVR U.P. AND 1035 MB HIGH BUILDING INTO WY. STILL HAVE GUSTS TO 25 KT REPORTED ON SFC OBS OVR MN AND NW WI. FACTORS GOING AGAINST REALLY STG WINDS OCCURRING: POST-FRONTAL GRAD WILL BE TIGHTEST LATE TONIGHT WHEN NOCTURNAL INVERSION SETTING UP WILL PREVENT FULL MIXING TO SFC AND ALSO ISALLOBARIC COMPONENT WILL ACTUALLY BE PERPENDICULAR TO GRAD WIND. DO NOT EXPECT WINDS TO APPROACH ADVISORY CRITERIA ANYWHERE IN CWA. TEMPS GENLY LOOK ON TARGET...SO NO BIG CHANGES THERE. .MQT...FLOOD WARNING MIZ005 ALONG DEAD RIVER FROM SILVER LAKE TO THE CITY OF MARQUETTE AND LAKE SUPERIOR UNTIL WATER RECEDES. GALE WARNING E HALF LAKE SUPERIOR. VOSS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1140 AM EDT MON MAY 19 2003 ...UPDATED FORECAST TO ADD SCATTERED SHOWERS FOR THIS AFTERNOON... WHILE THERE CURRENTLY IS NOT MUCH IN THE WAY OF SHOWERS AROUND...EXCEPT FOR THE CONVECTION ON THE COLD FRONT THERE IS A SHORTWAVE THE DOES SHOW UP ON THE WATER VAPOR IMAGES OVER CNTRL IOWA. THAT SHORTWAVE WILL MOVE EAST AND CROSS THE WARM FRONT (BASED ON DEW POINT DISCONTINUITY AND SURFACE PRESSURE PATTERN) WHICH AT 15Z WAS NEAR CHI TO SBN. BOTH THE ETA AND RUC SHOW A CONSIDERABLE INCREASE IN THE MEAN 850 TO 700 RH AS THAT SHORTWAVE MOVES INTO WRN LOWER MICHIGAN LATE THIS AFTERNOON. THERE IS SIGNIFICANT 700 TO 300 MB DPVA AND DECENT SFC TO 850 THTE ADVECTION AT THE SAME TIME. PWT VALUES INCREASE FROM AROUND 1" TO NEAR 1 1/2" OVER THE SW CORNER OF THE CWA BY 00Z. I HAVE TO ADMIT THE WARM ADVECTION/ISENTROPIC LIFT IS FEEBLE THOUGH. ALSO THERE IS A CONSIDERABLE AMOUNT OF UPSTREAM LOW LEVEL CLOUDS... SO SURFACE HEATING IS NOT MUCH OF A FACTOR EITHER. PUTTING ALL OF THIS TOGETHER... I ADDED SCATTERED SHOWERS TO THE AFTERNOON FORECAST OVER THE WESTERN CWA (WHERE THE BEST MOISTURE INCREASE IS). THERE DOES NOT SEEM TO BE ENOUGH INSTABILITY FOR THUNDERSTORMS THIS AFTERNOON OVER SOUTHWEST MICHIGAN. THE UPDATE HAS ALREADY BEEN ISSUED. .GRR...NONE. WDM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1113 AM EDT MON MAY 19 2003 BIGGEST FORECAST CONCERN WITH THIS FORECAST UPDATE IS THE COLD FRONT WHICH WILL APPROACH THE REGION THIS AFTERNOON. WATER VAPOR IMAGERY AND RUC/ETA SHOWING A RIDGE OVER THE LOWER GREAT LAKES AND A TROUGH OVER SOUTH CENTRAL CANADA. SHORTWAVE ENERGY BEING EJECTED OUT OF THE BASE OF THE TROUGH IS MOVING THROUGH MINNESOTA AND NORTHERN WISCONSIN. SURFACE ANALYSIS DEPICTS A COLD FRONT STRETCHING FROM A LOW OVER HUDSON BAY THROUGH KDLH AND KOMA TO A LOW OVER CENTRAL KANSAS. A 328K THETA-E RIDGE STRETCHES THROUGH ILLINOIS AND ANOTHER IS OVER COLD FRONT INTO WESTERN IOWA AND SOUTHERN MINNESOTA. THUNDERSTORMS ARE FIRING AHEAD OF THE COLD FRONT IN VICINITY OF THE SHORTWAVE AND THETA-E RIDGE MOVING THROUGH WESTERN IOWA. LAMP GUIDANCE TEMPERATURES ARE VERIFYING FAIRLY WELL THIS MORNING. THE SHORTWAVE WILL REACH INTO NORTHERN WISCONSIN THIS AFTERNOON. THE COLD FRONT WILL PUSH INTO NORTHERN WISCONSIN. THE THETA-E RIDGE WILL REACH WESTERN U.P. BY 21Z THIS AFTERNOON. A 30 KNOT LOW LEVEL JET WILL SHIFT OVER THE FORECAST AREA THIS AFTERNOON. HOWEVER...A SURFACE BASE INVERSION WILL LIMIT THESE WINDS FROM MIXING TO THE SURFACE. EXPECT ENOUGH MOISTURE AND INSTABILITY TO KEEP CLOUDY CONDITIONS THROUGH THE AFTERNOON. K-INDEX WILL REACH 34 OVER WESTERN U.P. SBCAPE WILL REACH ONLY ABOUT 500J/KG OVER THE WEST. LIFTED INDEX WILL DECREASE TO -2 OVER THE WEST. ISENTROPIC ANALYSIS SHOWING A FAIR AMOUNT OF ASCENT AHEAD OF THE FRONT. CONDITION LOOK FAVORABLE FOR THE CONTINUED DEVELOPMENT OF THUNDERSTORMS. HOWEVER...WITH MARGINAL LI'S AND CAPE...DO NOT EXPECT TO SEE ANY SEVERE. PLAN TO GO WITH CURRENT FORECAST...ONLY TO TWEAK THE WORDING. AS MORE PRECIPITABLE WATER INCREASES TO GREATER THAN 1.5 INCH OVER THE U.P. THIS EVENING...THUNDERSTORMS SHOULD BECOME MORE NUMEROUS. .MQT...FLOOD WARNING MIZ005 ALONG DEAD RIVER FROM SILVER LAKE TO THE CITY OF MARQUETTE AND LAKE SUPERIOR CONTINUES UNTIL WATER RECEDES. GALE WARNING E HALF LAKE SUPERIOR. DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 345 PM CDT MON MAY 19 2003 STRNG COLD FRNT 3/4 OF THE WAY THRU THE CWA AND IS THE MAIN CONCERN IN MY FCST PACKAGE. FRNT MAKING PROGRESS NOW AS LEAD H7 WAVE LIFTS OUT OF IA...AND MAIN H5 TROF MOVES INTO ERN DAKS. ENUFF INSTABILITY (SBLI TO -2C/CAPES TO 1000 J/KG/) TO DRIVE SOME WEAK CONVECTION IN BEST CONVERGENCE REGION OF FRNT FROM BALDWIN TO DURAND. SUPPOSE THERE COULD BE ENOUGH FOR AN ISOLD SVR EVENT VCTY KEAU THRU 23Z...BUT OVERALL INSTABILITY AND SHEAR NOT QUITE GREAT ENUFF FOR A MORE WIDESPREAD SVR RISK...DESPITE STRONG FORCING BOTH ALOFT IN RRQ OF JET AND IN FRONTAL ZONE WITH AID FROM S/W TROFS. BUT RADAR WL BE WATCHED CLOSELY FOR ANY FURTHER DVLPMNT. WL KEEP WND ADVRY IN WCNTL/SCNTL PER CURRENT WIND GUSTS AND CLEARING MOVING IN. NOT SMASHING CRITERIA BY ANY MEANS...BUT ENUFF GUSTS AOA 45MPH TO KEEP ADVRY AS BEST PRES RISES MOV THRU PER RUC. XPECT RAINS TO FOCUS MORE ON WCNTL WI THIS EVE...AND DIMINISHED POPS AND WORDING TO THE WEST AS STRONG SUBSIDENCE TAKES OVR FM WEST TO EAST. WENT ABV GUIDANCE MOST AREAS DUE TO WINDS AND AMPLE RAINS OF TDY. TUE/TUE NIGHT WL BE QUIET AND COOL...AS UNSEASONABLY STRONG SFC HI PRES MOVS RIGHT OVR CWA. SOME MIXING WINDS IN THE ERN CWA SHUD YIELD SOME GUSTS...AND REMNANT LL MOISTURE FIGURES TO POP SOME CU PER CU FORMATION RULES. AWFULLY COLD ALOFT...WITH H85 TEMPS HOVERING >5C. WENT MORE WITH MAV (WARMER) TEMPS GIVEN IT IS LATE MAY AND ANY SUN CAN WARM TEMPS INTO THE 60S PRETTY EASILY. RECENT RAINS/LIGHT WINDS/COLD TEMPS/CLEAR SKIES SPELLS FOR SOME GUD RADIATION FOG FORMING IN AREAS TUE NIGHT...ESP ERN CWA NEAR RIDGE AXIS. WED/WED NIGHT...NICE LITTLE WAVE SPILLS OVR BUILDING WRN RIDGE AND DROPS INTO DEVELOPING ERN CONUS TROF WED NIGHT. PRETTY DECENT PV ANOMALY WITH WAVE GIVEN NICE H25 80KT JETLET AND LAYER DIVERGENCE. MOISTURE WRAPPING ARND BACKSIDE OF BIG SFC HI WILL BE MEAGER BUT ENOUGH ALOFT TO DRIVE SOME WAA ACCAS AND SHRA. THIS PLODS ALONG THRU CWA WED AFTN AND EVENING. RIGHT ON ITS HEELS A BIGGER S/W HELPS CARVE OUT ERN TROF...AND BEGINS TO HELP CLOSE OFF CIRCULATION OVR GREAT LAKES. DISAGREEMENT HERE IN MDLS ON WHERE CLOSED CIRC WL DEVELOP...BUT ALL GUIDANCE SUGGEST THIS WILL BE A LARGE/COLD/CLOSED CIRC. WITH STRONG NEG HEIGHT AND TEMP ANOMALIES. SUBSEQUENT SHOWER CHANCES HINGE GREATLY ON THIS CIRCULATION'S LOCATION. WENT MORE MIDDLE OF THE ROAD...WITH BEST CHANCES THUR AND FRI...AND IN THE SOUTHEAST SAT. LOW CONFIDENCE HERE. .MSP...WIND ADVISORY THRU 6 PM SOUTH AND WEST OF A LINE FROM KAXN TO KAEL. $$ BINAU mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 300 PM CDT MON MAY 19 2003 MAIN FOCUS FOR THE SHORT TERM IS FLOODING POTENTIAL. THE STRONG COLD FRONT CONTINUES TO MARCH SLOWLY EASTWARD THIS AFTERNOON...WITH CONSIDERABLE FRONTAL AND PRE-FRONTAL RAIN. SOME THUNDERSTORMS HAVE JUST CROPPED UP IN THE UNSTABLE AIR IN NW WI. MSAS INDICATES -2C LI POKING INTO NW WI...WHICH IS IN LINE WITH THE LATEST RUC FORECAST. THE RUC POINTED TO THIS AREA NICELY THIS MORNING...SO WILL USE IT FOR THE SHORT TERM. WILL USE THE ETA FOR THE LONGER TERM...AS AVN APPEARS TO BE WAY TOO HEAVY ON QPF FOR THURSDAY. CANADIAN AGREES WITH ETA. THE BIG PROBLEM FOR TONIGHT WILL OBVIOUSLY BE THE FLOOD POTENTIAL IN NW WI. THE FRONT CONTINUES TO CHUG SLOWLY OFF TO THE EAST...BUT WITH SOME TRAINING POTENTIAL AHEAD OF THE FRONT WE WILL KEEP THE FLOOD WATCH GOING FOR THE NIGHT. PRECIPITABLE WATER VALUES HOVER AROUND 1.6 INCHES THROUGH THIS EVENING... SO CANNOT RULE OUT SOME PROBLEMS WITH RIVERS...STREAMS AND FULL DITCHES AND CULVERTS. THE MOS GUIDANCE HAS BEEN HINTING AT SIGNIFICANT CLEARING FOR THE PAST FEW MODEL RUNS...BUT WE WILL BE A LITTLE MORE CONSERVATIVE GIVEN THE UPPER TROUGH AND VORT MAX MOVING OUT OF THE FAR NORTHERN PLAINS. THERE COULD BE A PERIOD OF CLEARING...BEFORE THE CLOUDS NEAR THE VORT AND UPPER TROUGH MOVE IN. THE GROUND WILL ALSO BE WET FROM TODAY'S RAINFALL...SO THAT WILL SLOW DOWN THE CLEARING. DON'T THINK FROST WILL BE A WIDESPREAD PROBLEM TONIGHT DUE TO SOME WIND. THINK THE MORE SIGNIFICANT FROST POTENTIAL WILL BE TUESDAY NIGHT. OUR OFFICE HAS NOW BEGUN TO ISSUE FROST AND FREEZE HEADLINES FOR THE SEASON...AND A FROST ADVISORY MAY BE NEEDED FOR TUESDAY NIGHT IF THINGS COME TOGETHER AS EXPECTED. MOS TEMPS ARE QUITE VARIED. HAVE WENT ON THE COOLER SIDE FOR THE NIGHTTIME TEMPS...AND ALSO FOR THE DAYTIME TEMPS ON WEDNESDAY. .DLH...FLOOD WATCH WIZ001>004-006>009. $$ DAP mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 1115 AM CDT MON MAY 19 2003 MAIN FOCUS FOR THE AFTERNOON IS POTENTIAL FLOODING IN NW WI. THE PREFRONTAL BAND OF SHOWERS AND ISOLATED THUNDERSTORMS CONTINUED TO MOVE SLOWLY EAST THIS LATE MORNING. THE MAIN PROBLEM FOR THE AFTERNOON HINGES ON THE FLOOD WATCH CURRENTLY IN PLACE ACROSS NW WI. COOPERATIVE OBSERVERS THIS MORNING REPORTED SEVERAL AMOUNTS AROUND 1.25 INCHES...FROM BOVEY TO EMILY TO BRAINERD. THE LATEST RUC GUIDANCE INDICATES THAT THE LI VALUES WILL DROP TO ABOUT -3C ACROSS NW WI...WITH PRECIPITABLE WATER OF 1.6 INCHES. WITH SUCH A SLOW MOVING BAND OF PRECIPITATION AND THE POTENTIAL FOR SOME SLOW MOVING EMBEDDED THUNDERSTORMS THIS AFTERNOON...WILL HANG ON TO THE FLOOD WATCH. COULD BE SOME TRAINING OF STORMS ALONG AND AHEAD OF THE FRONT AS WELL. SINCE THE GROUND HAS NOT HAD A LOT OF TIME TO DRY OUT FROM THE LAST DELUGE...RIVERS AND STREAMS MAY RESPOND RATHER QUICKLY. TEMPS WILL BE QUITE VARIED TODAY...WITH TEMPERATURES POSSIBLY DROPPING HOLDING IN THE 50S IN THE WESTERN CWA...AND REACHING THE LOWER TO MIDDLE 70S IN NW WI. GUSTY NORTHWEST WINDS STILL ANTICIPATED FOR THE AFTERNOON...WITH SOME GUSTS ALREADY SHOWING UP AT INL AT 16Z. .DLH...FLOOD WATCH WIZ001>004-006>009. $$ DAP mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 335 PM CDT MON MAY 19 2003 ...MAIN FORECAST CONCERNS ARE THUNDERSTORM CHANCES TONIGHT AND TEMPERATURES TUESDAY NIGHT... THIS AFTERNOON'S WATER VAPOR IMAGERY SHOWED SHORTWAVE ENERGY TRACKING ACROSS THE NORTHERN PLAINS...THIS FEATURE HELPED TO DRAG A COLD FRONT INTO CENTRAL PORTIONS OF KANSAS AND OKLAHOMA. IN ADDITION...UPPER LEVEL DIFFLUENCE WAS NOTED ACROSS MUCH OF MISSOURI. CONVECTION WAS FIRING BOTH IN ADVANCE AND BEHIND THE FRONT ACROSS NORTH-CENTRAL AND NORTHEAST KANSAS. THIS CONVECTION DEVELOPED IN A REGION OF STRONG 1000-850 MB F-VECTOR CONVERGENCE. NO SHOWERS OR THUNDERSTORMS HAVE AFFECTED THE FORECAST AREA SO FAR TODAY. THE 12Z SOUNDING AT SGF SHOWED A STRONG CAPPING INVERSION...THIS SUPPRESSED THE MORNING CONVECTION WHICH TRIED TO PUSH EAST OUT OF CENTRAL KANSAS. BOTH THE RUC AND MESOETA SHOW THIS CAP WEAKENING DURING THE LATE AFTERNOON/EARLY EVENING HOURS. IN ADDITION...19Z LAPS DATA SHOWED CAPE VALUES INCREASING IN EXCESS OF 1000 J/KG ACROSS SOUTHEAST KANSAS AND WESTERN MISSOURI WHERE SURFACE TEMPERATURES HAD RISEN INTO THE LOWER 80S. THE FRONT WILL PUSH INTO THE OZARKS THIS EVENING...WITH SHOWERS AND THUNDERSTORMS INITIALLY DEVELOPING ACROSS FAR EASTERN KANSAS AND WESTERN MISSOURI. QUITE STRONG 1000-850MB F-VECTOR FORCING WILL BE FOUND JUST BEHIND THE FRONT. WITH THIS IN MIND...CONTINUED THE ONGOING LIKELY POPS ACROSS THE WHOLE AREA. WITH MARGINAL INSTABILITY AND WEAK WIND SHEAR...THE SEVERE THREAT LOOKS TO BE LOW TONIGHT...WITH THE STRONGEST STORMS HAVING THE POTENTIAL TO PRODUCE PENNY TO NICKEL SIZE HAIL. SOME GUSTY NORTHERLY WINDS WILL BE FOUND BEHIND THE FRONT...BEGINNING LATE TONIGHT AND CONTINUING INTO TUESDAY. BUFKIT SOUNDINGS INDICATE GUSTS MAY APPROACH 30 MPH AT TIMES. A STRONG AREA OF HIGH PRESSURE SETTLES OVER THE REGION TUESDAY NIGHT INTO EARLY WEDNESDAY...CAUSING SKIES TO CLEAR AND WINDS TO BECOME NEARLY CALM. THIS SET UP IS VERY FAVORABLE FOR STRONG RADIATIONAL COOLING. IN ADDITION...A UNSEASONABLY COOL AIRMASS WILL BE IN PLACE. AT 06Z WEDNESDAY...850 MB TEMPERATURES ACROSS OUR NORTHERN COUNTIES WILL ONLY RANGE FROM 3 TO 4 DEG C. STAYED PRETTY CLOSE TO PREVIOUS FORECAST...WHICH WAS COOLER THAN YESTERDAY'S GUIDANCE. CONFIDENCE IS RISING IN THIS COLDER SOLUTION...AS 12Z MET GUIDANCE HAS TRENDED COOLER. IT GAVE LOWS IN THE UPPER 30S FOR AIZ AND VIH...DID NOT WANT TO GO THAT COLD YET...HOWEVER. RIGHT NOW I THINK RECORD LOWS ARE SAFE ACROSS MOST LOCATIONS...EXCEPT FOR PARTS OF CENTRAL MISSOURI. FORECAST LOWS WILL BE IN THE LOWER 40S ACROSS MUCH OF THE OZARKS...WITH MIDDLE 40S ACROSS FAR SOUTHERN MISSOURI. WITH GOOD RADIATIONAL COOLING...COOLER TEMPERATURES AND SCATTERED FROST COULD OCCUR IN VALLEYS AND LOW-LYING AREAS...THESE LOCATIONS MAY DROP INTO THE UPPER 30S. HERE ARE THE RECORD LOWS FOR WEDNESDAY... SGF 36 (1892) UNO 36 (1954) JLN 40 (1968) VIH 40 (2002) IN THE EXTENDED PERIOD DAYS 4 THROUGH 7 (THURSDAY THROUGH SUNDAY) THE GFS AND ECMWF ARE IN DECENT AGREEMENT THROUGH FRIDAY NIGHT. BOTH MODELS DEPICT NORTHWEST FLOW OVER THE OZARKS REGION AS AN UPPER RIDGE BUILDS OVER THE INTERMOUNTAIN WEST. MODELS BEGIN TO DIFFER BY SATURDAY MORNING WITH THE HANDLING OF SHORTWAVE ENERGY ACROSS THE UPPER MIDWEST. THE GFS PRODUCES A CUT-OFF LOW AND SHOWS THIS FEATURE DRIFTING OVER THE WESTERN OHIO RIVER VALLEY ON SATURDAY AND SUNDAY. IN CONTRAST...THE ECMWF KEEPS THE BULK OF THE ENERGY ACROSS CANADA AND THE GREAT LAKES REGION. ALL IN ALL...NOTHING CONCRETE IN THE LATEST DATA THAT WOULD INDICATE ADDING POPS TO THE FORECAST THROUGH SUNDAY...DID NOT CHANGE MUCH IN THE GOING GRIDS. $$ SAW mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 909 AM EDT MON MAY 19 2003 CURRENT OBS SHOW PERSISTENT COOL MOIST NORTHEAST FLOW IN THE LOWER LAYERS WITH TEMPERATURES MUCH BELOW NORMAL EXPECTED TODAY. CROSS SECTIONAL ANALYSIS OF OBSERVED DATA AND SHORT RANGE MODEL PROJECTIONS FROM THE RUC SHOW SUBSIDENCE BEGINNING IN THE NORTHEAST AROUND WAL THIS MORNING AND WORKING SOUTHWEST INTO THE RAH CWA THIS AFTERNOON. THIS TURNS CURRENT CONFLUENT UPGLIDE FLOW ON THE 300-310K THETA SURFACES TO SINKING MOTION. LINGERING RAIN SHOULD DIMINISH THE NEXT COUPLE OF HOURS. OVERCAST WILL CONTINUE SOUTH AND WEST...BUT A FEW BREAKS TO PARTLY SUNNY SKIES ARE EXPECTED NORTHEAST OF ROXBORO TO RDU TO WILSON THIS AFTERNOON. UPDATED FORECASTS WILL REFLECT THESE TRENDS. .RAH...NONE. RFG nc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE NORMAN OKLAHOMA 820 PM CDT MON MAY 19 2003 COLD FRONT WILL CONTINUE TO MOVE ACROSS THE REMAINDER OF SOUTH CENTRAL AND SOUTHEAST OKLAHOMA DURING THE NEXT FEW HOURS. THUNDERSTORMS WILL ALSO CONTINUE ALONG AND NEAR THE FRONT... ALTHOUGH SHOULD SEE A GRADUAL DECREASE IN INTENSITY AS INSTABILITIES WEAKEN. WILL STILL HAVE A CHANCE FOR SCTD SHWRS/TSTMS OVER PORTIONS OF CENTRAL... NORTHERN AND SOUTHWEST OKLAHOMA... AND THE WESTERN PART OF NORTH TEXAS OVERNIGHT. LATEST RUC RUN INDICATING FRONTOGENETIC FORCING COINCIDING WITH ELEVATED INSTABILITIES... WILL SUPPORT ADDITIONAL SCTD SHWRS/TSTMS IN THESE AREAS. GUSTY NORTH WINDS WILL PERSIST BEHIND THE FRONT THROUGH MUCH OF THE NIGHT... ALTHOUGH THE OCCASIONAL HIGHER GUSTS TO NEAR 40 MPH WILL SUBSIDE. FCSTID = 32 ______________________________________________ 343 PM CDT MON MAY 19 2003 COLD FRONT CONTINUES TO ADVANCE SOUTHEAST ACROSS OUR FORECAST AREA... EXTENDING FROM NEAR ENID TO ALTUS AT 3 PM. THE FRONT SHOULD CONTINUE ITS SOUTHEAST PROGRESSION OVERNIGHT... AND WILL PROVIDE A NICE FOCUS FOR THUNDERSTORM DEVELOPMENT. THERE IS A FAIRLY STRONG CAP TO OVERCOME... BUT ELEVATED STORMS HAVE ALREADY FORMED IN OUR SOUTHWEST COUNTIES. MID-LEVEL TEMPERATURES ARE FORECAST TO COOL THIS EVENING... SO ADDITIONAL STORM DEVELOPMENT SHOULD NOT BE TOO DIFFICULT OVER THE SOUTHEAST HALF OF OUR AREA. SOME HEAVY RAIN IS LIKELY IN OUR SOUTHEASTERN COUNTIES... FROM ABOUT ARDMORE TO COALGATE AND EAST FROM THERE... BUT AT THIS POINT IT LOOKS LIKE MOST OF THAT WOULD BE READILY SOAKED UP BY THE SOIL. ON THE OTHER SIDE OF THE FRONT... DRIZZLE AND STRONG NORTH WINDS ARE COMMON. WILL ATTEMPT TO INCLUDE DRIZZLE IN THE ZONE FORECAST... AND IT IS IN THE GRIDS. BEYOND TONIGHT... RATHER FEW CHANGES WERE MADE TO THE FORECASTS. THE NEW GFS/MRF HAS A DEEP CUTOFF LOW OVER THE MIDWEST IN THE LATER PERIODS... BUT THERE IS NO OTHER SUPPORT FOR THAT IDEA. HAVE ELECTED TO ADJUST FOR A MORE NORTHEASTERN POSITION FOR THE CUTOFF LOW... AND A LESS-INTENSE ONE. THIS BRINGS US RIGHT BACK TO THE PREVIOUS FORECAST. OKC 55 69 50 74 / 40 0 10 0 HBR 52 69 49 75 / 20 10 10 0 SPS 59 72 52 76 / 50 30 30 20 GAG 44 65 45 73 / 20 5 0 0 PNC 52 65 47 73 / 40 10 0 0 DUA 65 73 55 76 / 60 30 30 20 FORECAST ID = 23 .OUN... OK...NONE. TX...NONE. ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1016 AM EDT MON MAY 19 2003 SATELLITE IMAGERY THIS MORNING REVEALS ALMOST COMPLETELY OVERCAST SKIES OVER THE CWFA...EXCEPT FOR SOME BREAKS ALONG THE FRENCH BROAD VALLEY TOWARD THE TENNESSEE BORDER. AREA SOUNDINGS REVEAL ABUNDANT LOW LEVEL MOISTURE...WHICH WILL BE HARD TO SCOUR TODAY DESPITE THE PRESENCE OF DRY AIR ALOFT. WATER VAPOR IMAGERY SHOWS ADDITIONAL DRY AIR PUMPING INTO THE REGION FROM THE NORTH. TO THE SOUTHWEST...THE UPPER LOW CONTINUES TO SPIN CLOSE TO THE GULF COAST AND SLIPS SLOWLY SOUTHWARD. AT THE SURFACE...COOL HIGH PRESSURE CONTINUES TO BUILD INTO THE SOUTHEAST STATES FROM THE NORTHEAST. WEDGE FRONT...OR BOUNDARY BETWEEN REALLY JUICY AIR TO OUR SOUTHWEST...CONTINUES A SLOW DRIFT SOUTHWARD. WITHIN THE DAMMING REGION...THERE RESIDE A FEW SURFACE TROFS...OR WIND SHIFT AXES...WHICH OCCASIONALLY MAKE THEMSELVES KNOWN ON THE RADAR IMAGERY IN THE WAY OF BOUNDARIES AND/OR ATTEMPTED ORGANIZED LINES OF LIGHT RAIN. PRECIPITATBLE WATER ON THE FFC SOUNDING THIS MORNING VERY HIGH. LATEST RUC AND 06Z ETA BOTH PROG A FLATTENING UPPER VORT TO ROTATE AROUND THIS LOW...WITH BOTH MODELS PRODUCING A LINE OF AFTERNOON CONVECTION FROM NORTH GEORGIA SOUTH ALONG THE WEAK WEDGE FRONT INTO SOUTH CAROLINA. HOWEVER...SUBSIDENCE WILL BE INCREASING FROM THE NORTH TODAY...AND MAY GET AN ENHANCEMENT FROM THE BACK SIDE OF ANOTHER UPPER LOW SPINNING OFF THE MID ATLANTIC. FOR THE UPDATE...DECIDED TO KEEP 50 POPS IN TH3 SOUTHWEST CWFA...AND TAPER OFF TO 30S EASTWARD TO THE NORTHWEST PIEDMONT AND THE CHARLOTTE AREA FOR THE AFTERNOON. WILL CONTINUE CHANCE OF RAIN/DRIZZLE WORDING...ALTHOUGH COULD NOT RULE OUT A CONVECTIVE ELEMENT OR TWO THIS AFTERNOON WITH ANY HEATING...ALTHOUGH IT WILL BE MINIMAL. INCREASED WIND SPEEDS TO BETWEEN 10 AND 15 EVERYWHERE TODAY...EXCEPT 15 TO 20 FROM THE NORTHEAST IN THE SOUTH CAROLINA AND GEORGIA MOUNTAINS. WITH FEW...IF ANY...BREAKS IN THE OVERCAST EXPECTED THIS AFTERNOON...TRENDED LOWER ON MAX TEMPS...OPENING UP A RANGE OF 60 TO 65 MOST AREAS...WITH 61 TO 66 FOR NORTHEAST GEORGIA AND THE MAJORITY OF UPSTATE SOUTH CAROLINA. FCSTID = 44 GSP 63 56 73 61 / 40 30 40 60 AND 64 57 74 62 / 50 30 50 60 CLT 63 56 72 61 / 30 20 20 50 HKY 62 54 72 60 / 30 20 30 60 AVL 63 54 71 57 / 40 30 60 80 .GSP... GA...NONE. NC...NONE. SC...NONE. $$ BURRUS sc SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 320 AM EDT TUE MAY 20 2003 AN UPPER LEVEL TROUGH MOVING ACROSS THE UPPER MISSISSIPPI VALLEY HAS AN ASSOCIATED COLD FRONT EXTENDING ACROSS EXTREME EASTERN WISCONSIN INTO SE MISSOURI. AREA RADAR DATA SHOWS AN AREA OF SHOWERS AND THUNDERSTORMS EXTENDING ALONG AND JUST AHEAD OF THE SURFACE COLD FRONT. THE PRECIPITATION HAS DEVELOPED ALONG A REGION OF DEEP FRONTOGENETICAL FORCING WITHIN THE ENTRANCE REGION OF AN UPPER LEVEL SPEED MAX CENTERED OVER NORTHERN ONTARIO. 00Z SOUNDING ANALYSES ACROSS THE MISSISSIPPI VALLEY...AHEAD OF THE FRONT...HAD AMPLE MOISTURE FROM THE SURFACE TO 500MB TO SUPPORT WIDESPREAD PRECIPITATION ALONG THE FRONT. PRECIPITABLE WATER VALUES OF 1.5 INCHES ALSO EXTENDING INTO NORTHERN ILLINOIS. THIS AREA OF PRECIPITATION WILL WORK ITS WAY ACROSS SOUTHEAST LOWER MICHIGAN THIS MORNING AS THE COLD FRONT PUSHES EAST. BASED ON AREAL COVERAGE OF THE SHOWERS ON UPSTREAM RADARS...CATEGORICAL WORDING STILL LOOKS WARRANTED. SOME DRYER AIR IN THE MID LEVELS OVER THE EASTERN LAKES REGION RESULTING FROM SUBSIDENCE WITHIN THE MID LEVEL RIDGE AXIS NOW DEAMPLIFYING OVER THE EASTERN LAKES SEEMS TO BE CONFINING THE MORE WIDESPREAD SHOWERS CLOSER TO THE SURFACE COLD FRONT. THIS SHOULD LIMIT THE DURATION OF THE MORE WIDESPREAD RAINFALL TO AN HOUR OR TWO AS IT MOVES ACROSS THE AREA THIS MORNING. THE ETA SOLUTION IS A COUPLE HOURS SLOWER AT BRINGING THE SURFACE FRONT THROUGH TODAY IN COMPARISON TO THE GFS. BASED ON THE CURRENT POSITION OF THE FRONT AND THE LATEST RUC SOLUTION...THE SLIGHTLY SLOWER ETA SOLUTION SEEMS MORE REASONABLE. BASED ON THIS...THE FRONT SHOULD MOVE INTO THE WESTERN PORTIONS OF THE FORECAST AREA AROUND 12Z AND EXIT TO THE EAST OF PORT HURON AROUND 18Z. CAPE COMPUTED FROM 925MB ON MODEL SOUNDINGS SHOWS A COUPLE HUNDRED JULES THIS MORNING...WITH SHOWALTER INDICES PROGGED AROUND -1C. THIS WILL CERTAINLY SUPPORT THUNDER. SEVERE THREAT STILL LOOKS TO BE NON EXISTENT THOUGH AS INSTABILITY WILL JUST BE TOO WEAK. STRONG SUBSIDENCE/ISENTROPIC DESCENT WILL WORK INTO THE AREA IN THE WAKE OF THE SURFACE COLD FRONT. 850MB TEMPS WILL ALSO FALL NEARLY 10 DEGREES LATE THIS AFTERNOON AND EVENING. THE STRONG COLD AIR ADVECTION WILL BOOST MIXING HEIGHTS...WHICH SHOULD LEAD TO A BRIEF PERIOD OF GUSTY WINDS AT THE ONSET OF COLD AIR ADVECTION. ETA MODEL SOUNDINGS INDICATE MOISTURE IN THE 2K TO 4K FT LAYER WILL REMAIN TRAPPED UNDER A STRENGTHENING SUBSIDENCE INVERSION THROUGH MUCH OF THE NIGHT. MOS GUIDANCE HOWEVER SUGGESTS A RAPID CLEARING FROM WEST TO EAST LATE THIS AFTERNOON THROUGH EARLY EVENING. WITH SATELLITE DATA SHOWING CLEAR SKIES ACROSS IOWA AND SOUTHERN MINNESOTA...I WILL LEAN THE FORECAST TOWARD MOS AND HAVE SKIES CLEAR DURING THE EVENING. THE SURFACE PRESSURE GRADIENT OVER SOUTHEAST MICHIGAN SHOULD PREVENT THE BOUNDARY LAYER FROM DECOUPLING. I WILL THUS KEEP FCST LOWS NEAR GUIDANCE (UPPER 30S NORTH TO LOWER 40S SOUTH) AND NOT MENTION FROST. SURFACE HIGH PRESSURE AND VERY DRY AIR STILL LOOKS POISED TO PUSH INTO THE REGION BY WEDNESDAY. THIS WILL SUPPORT COOL AND DRY CONDITIONS THROUGH MID WEEK...WHICH THE CURRENT ZONE AND GRIDDED FORECAST HAS COVERED WELL. THERE STILL LOOKS TO BE A FROST POTENTIAL ACROSS THE NORTH WEDNESDAY NIGHT WHERE THE SURFACE PRESSURE GRADIENT WILL BE A LITTLE WEAKER. WITH THE ETA INDICATING SOME HIGH CLOUDS MOVING IN AND SHOWING 925MB WINDS OF 20KTS OVER THE ENTIRE AREA THROUGH THE NIGHT...I WILL KEEP FCST MIN TEMPS IN THE MID TO UPPER 30S ACROSS THE NORTH AND REFRAIN FROM MENTIONING FROST AT THIS TIME EXCEPT FOR CLIMATOLOGICALLY FAVORED AREAS IN THE NORTHERN THUMB. FROST POTENTIAL WEDNESDAY NIGHT WILL CONTINUE TO BE MONITORED THE NEXT SEVERAL FORECAST PERIODS. THE GFS HAS TRENDING FASTER AT DEVELOPING A CUT OFF UPPER LOW OVER THE GREAT LAKES BY THE END OF THE WEEK. THE GFS ALSO BRINGS A POTENT SHORT WAVE AND DEEP MOISTURE INTO THE AREA ON FRIDAY. WITH THE UKMET AND TO A GREATER DEGREE THE ETA MUCH WEAKER AND SLOWER WITH THE DEVELOPMENT OF THE UPPER TROUGH...I WILL NOT ADD PRECIP TO FRIDAY AT THIS TIME. .DTX...NONE. $$ CONSIDINE EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 320 AM EDT TUE MAY 20 2003 00Z RAOBS/LATEST WV LOOP/RUC ANLSYS SHOW POTENT SHRTWV MOVG E THRU THE NRN PLAINS AND CRASHING INTO HI AMPLITUDE RDG OVR ERN NAMERICA. ASSOCIATED SHARP SFC COLD FNT NOW ENTERING WRN CWA AT 03Z WITH A BAND OF SHRA IN ADVANCE OF FNT AND FOCUSED ON PREFRONTAL TROF ASSOCIATED WITH ANOTHER WEAKER SHRTWV THAT MOVED NE IN SWLY AHD OF STRGR NRN PLAINS SHRTWV. SOME OF THE RA HAS BEEN HVY...IWD RECORDED 0.36 INCH/ONE HR...WITH PCPN INTENSITY ENHANCED BY PWAT APRCHG 1.50 INCH (200 PCT NORMAL) AND LIFT IN RRQ OF 100+ KT H3 JET MAX LIFTING NE THRU FAR NW ONTARIO INTO HUDSON BAY. DESPITE MSTR/DYNAMICS...NO LTG OBSVD ACRS CWA WITH CONSIDERABLE SC IN SLY FLOW AHD OF TROF/FNT LIMITING DAYTIME HTG/LLVL DESTABILIZATION. DLH 88D/SFC OBS TO W INDICATE SHRA COVG DECREASES TO SCT BEHIND SFC FNT...WITH IMPRESSIVE DRY ADVCTN AT H5 IN DRY SLOT OF NRN PLAINS SHRTWV OFFSETTING LIFT. 00Z BIS/INL SDNGS HOWEVER INDICATE HIER LWR TROP MSTR LINGERS WELL BEHIND SFC FNT...WITH SFC OBS SHOWING SC CIGS AS FAR W AS ND AT 03Z TO H85 THERMAL TROF AXIS. 00Z YQD SDNG IS QUITE A BIT DRIER. TEMPS FALL OFF SHARPLY BEHIND SFC FNT...WITH 04Z TEMP AT DLH ALREADY DOWN TO 43. NW WNDS BEHIND THE FNT ARE GUSTING AS HI AS 30-35 MPH IN ADVANCE OF 1034MB SFC HI PRES IN THE WRN SD. LLVL DESTABILIZATION WL ALSO THOROUGHLY MIX HIER MOMENTUM MAIN FCST CONCERNS TDAY ARE PCPN/CLD/WND TRENDS. FOCUS FOR LATER PDS TURNS TO TEMPS WITH SFC HI PRES BLDG INTO THE UPR GRT LKS. 00Z MODELS SHOW NRN PLAINS SHRTWV LIFTING NE INTO ONTARIO TDAY. ETA SHOWS SFC FNT CLRG ERY BY FCST ISSUANCE TIME AND BACK EDGE OF DEEPER H85-5 MSTR/H4-2 DVGC/H85-5 QVECTOR CNVGC/AND H7 UVM PASSING E OF ERN CWA BTWN 12Z-18Z...BUT WITH H5 HIER VORT AXIS/H85 THERMAL TROF HANGING BACK AND NOT REACHING IWD UNTIL 18Z AND ERY UNTIL 00Z. SO EVEN THOUGH FCST FIELDS SUG PCPN WL END OVR THE ERN CWA THIS MRNG... XPCT SC CIGS TO PERSIST UNTIL H85 THERMAL TROF PASSES WITH DIURNAL HTG/DESTABILIZATION MAINTAINING SC CIGS DESPITE LLVL DRYING UNDER STRENGTHENING MID LVL SUBSIDENCE INVRN. XPCT GUSTY WNDS IN ADVANCE OF H85 THERMAL TROF ARRIVAL WITH ENHANCED MIXING OF MOMENTUM TO SFC. ETA SHOWS H925 WND SPEEDS AS HIGH AS 30-35KT...SO WL CARRY WINDY WORDING IN ALL ZNS. MODELS SHOW PRES GRADIENT SLACKENING OVR THE W 1/2 LATER IN THE DAY FOLLOWING PASSAGE OF H85 THERMAL TROF...SO WNDS SHUD DIMINISH STEADILY THIS AFTN THERE BUT CONT HI ALL DAY ACRS THE E 1/2. UPSTREAM MAX TEMPS YDAY GENERALLY ARND 50...XPCT COOLER READINGS ACRS THE E DOWNSTREAM OF LK SUP WITH NW FLOW AND HIER MAX ACRS THE DOWNSLOPING SCNTRL AND ACRS THE W WELL INLAND FM LK SUP AND NR THE WI BORDER WITH MORE SUNSHINE THIS AFTN FOLLOWING PASSAGE OF THERMAL TROF. FOR TNGT...MODELS SHOW SFC HI PRES BLDG TO SRN WI BY 12Z WED. AS THERMAL TROF PASSES E OF CWA ARND 00Z AND PRES GRADIENT SLACKENS... XPCT LINGERING SC TO DISSOLVE QUICKLY AND WINDS OVR THE E TO DIMINISH WITH LOSS OF DIURNAL HTG. SINCE INCOMING AIRMASS QUITE DRY (PWAT FCST DOWN ARND 0.25 INCH) AND SKIES WL BCM CLR...POTENTIAL FOR TEMP TO FALL OFF SHARPLY TOWARD AFTN DWPTS XPCTD TO BE IN 25 TO 30 RANGE. LOOKS LIKE GOOD BET FOR MINS TO FALL BLO FRZG INLAND OVR ENTIRE CWA XCPT THE KEWEENAW PENINSULA...WHERE MODELS SHOW SOMEWHAT SHARPER PRES GRADIENT/WLY FLOW DURG NGT BTWN SFC HI TO THE S AND LO PRES TROFFING ACRS ONTARIO ASSOCIATED WITH SHRTWV MOVG E THRU NEARLY ZONAL FLOW ALF. SFC HI PRES PROGGED TO LINGER OVR THE CNTRL LKS ON WED. BUT UPR FLOW REMAINS WNW...AND SHRTWV RESPONSIBLE FOR SFC TROFFING IN ONTARIO TNGT FCST TO MOVE TOWARD WRN LK SUP. ALTHOUGH LWR TROP WL REMAIN MUCH TOO DRY FOR ANY PCPN (OR EVEN CU PER ETA FCST SDNGS) WITH GENERAL ACYC SW FLOW...BOTH ETA/GFS INDICATE AN INCRS IN MID/UPR RH ASSOCIATED WITH THIS FEATURE ESPECIALLY ACRS THE NRN TIER ZNS CLOSER TO TRACK OF THIS SYS AND FARTHER N OF SFC RDG AXIS. SUSPECT SKIES WL REMAIN MOSUNNY ACRS THE S...BUT WL GO WITH SCT-BKN AC FCST FOR THE NRN TIER DURG THE AFTN PER ETA/GFS MOS UNDER SUBTLE H5 THERMAL TROF. ETA/GFS SHOW H85 TEMPS ARND 4C...AND MIXING TO H85-8 WOULD SUPPORT GOING MAX TEMPS IN 60 TO 65 RANGE. ACYC SW FLOW DOES NOT FAVOR MUCH LK SUP MODERATION...BUT TEMPS WL BE COOLER NR THE LK MI SHORE. CWA PROGGED TO REMAIN IN LGT ACYC SW FLOW WED NGT UNDER WEAK UPR TROFFING AND SLOW-MOVG SHRTWV. COMBINATION OF INCRSG SW FLOW... ESPECIALLY OVR THE WRN TIER...AND SCT-BKN AC WL LIMIT DIURNAL TEMP FALL AND HOLD READINGS UP AT LEAST SVRL DEGREES HIER THAN TNGT. AREAS ACRS THE SCNTRL WL LIKELY SEE THE LOWEST MINS CLOSER TO THE SFC HI CENTER AND THE LIGHTEST WNDS. COORDINATED WITH APX. .MQT...FLOOD WARNING MIZ005 ALONG DEAD RIVER FROM SILVER LAKE TO THE CITY OF MARQUETTE AND LAKE SUPERIOR UNTIL WATER RECEDES. GALE WARNING E HALF LAKE SUPERIOR. KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1100 AM EDT TUE MAY 20 2003 STRONG COLD FRONT LOCATED IN THE VICINITY OF DETROIT AND INDIANAPOLIS...WHILE MID ATLANTIC REGION REMAINS UNDER INFLUENCE OF HIGH PRESSURE. THE 500 MB RIDGE IS FORECAST TO FLATTEN/MOVE EAST DURING THE AFTERNOON. THIS WILL ALLOW ADDITIONAL UPPER LEVEL MOISTURE TO ADVECT EASTWARD. RAIN LOCATED IN OHIO ASSOCIATED WITH WARM ADVECTION IS PROGGED TO ENTER CWA THIS EVENING INTO TONIGHT. LOWER CLOUD DECK WILL EXPAND EASTWARD INTO THE MOUNTAINS DURING THE AFTERNOON HOURS. HAVE UPDATED ZONES TO TWEAK CLOUD WORDING. TEMPERATURES/WINDS LOOK ON TARGET GIVEN RUC CROSS SECTIONS AND SOUNDINGS. ROGOWSKI .LWX... DC...NONE. MD...NONE. VA...NONE WV...NONE. MARINE...NONE. md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1106 AM EDT TUE MAY 20 2003 THE MAIN CONCERN WITH THIS UPDATE FORECAST IS THE WINDS. WATER VAPOR IMAGERY AND RUC/ETA SHOWING A RATHER PRONOUNCED SHORTWAVE OVER THE FORECAST AREA...WITH A NEAR ZONAL FLOW ACROSS THE WESTERN TWO THIRDS OF THE NORTHERN CONUS. IN THE WAKE OF THIS SHORTWAVE ARE WEAKER SHORTWAVES OVER MONTANA AND IDAHO. SURFACE ANALYSIS INDICATE A COLD FRONT OVER EASTERN ONTARIO AND LOWER MICHIGAN. WITH A BROAD HIGH BUILDING BEHIND IT OVER THE NORTHERN PLAINS. A 30-35 KNOT LOW LEVEL JET IS OVER THE FORECAST AREA THIS MORNING. BY LATE AFTERNOON THE HIGH WILL PUSH INTO THE MIDDLE MISSOURI RIVER VALLEY. AS IT DOES...IT WILL RELAX THE GRADIENTS OVER THE UPPER GREAT LAKES AND THUS ALLOWING THE WINDS TO GRADUALLY TAPER OFF. THE LOW LEVEL JET WHICH IS OVER WESTERN U.P. WILL MOVE OVER THE SOO BY LATE AFTERNOON. AS DRIER AIR ADVECTS INTO THE FORECAST AREA THIS AFTERNOON...THERE SHOULD BE AN INCREASE IN SUN...WHICH WILL GENERATE SOME CONVECTIVE CLOUDS WHICH ARE ALREADY SHOWING UP ON VISIBLE IMAGERY. KINL SOUNDING SHOWING A SHARP INVERSION AT 800MB WHICH SUPPORTS LIMITING CONVECTION. COLD AIR ADVECTION ABOVE SURFACE AND SURFACE HEATING...SHOULD INCREASE THE WINDS MIXING TO SURFACE. THUS WILL KEEP WINDS STRONG EARLY...THEN TAPERING OFF OVER THE WEST AS THE LOW LEVEL JET MOVES EAST THIS AFTERNOON. DRIER AIR ADVECTING INTO THE AREA TONIGHT AS THE HIGH MOVES INTO THE UPPER GREAT LAKES. WINDS WILL CONTINUE TO TAPER OFF AND SKIES SHOULD CLEAR. COLD AIR ADVECTION ENHANCED BY RADIATIONAL COOLING WILL ALLOW TEMPERATURES TO FALL TO NEAR FREEZING OVERNIGHT. .MQT...NONE. DLG mi SOUTHEAST MICHIGAN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1050 AM EDT TUE MAY 20 2003 SURFACE ANALYSIS/METARS SHOW COLD FRONT MAKING PROGRESS ACROSS LOWER MICHIGAN. MAIN BAND OF PRECIP LEADING THE FRONT IS CURRENTLY CLEARING THE EASTERN CWA PER REGIONAL RADARS. SCATTERED LIGHT SHOWERS EXTEND BACK ACROSS WESTERN LOWER BEHIND THE FRONT. A FEW LIGHTNING STRIKES PICKED UP JUST SOUTH AND JUST NORTH OF THE CWA IN THE HEAVIER PRECIP. MARGINAL ELEVATED INSTABILITY AHEAD OF THE FRONT WITH SHOWALTERS NEAR 0C...WHICH IS ALMOST THROUGH THE CWA. WILL NEED TO CARRY SCATTERED THUNDERSTORMS IN THE MARINE AREAS FOR A FEW MORE HOUS...BUT SHOULD BE ABLE TO PULL THEM FROM THE LAND ZONES. EXPECT A FEW MORE HOURS OF SCATTERED LIGHT SHOWERS OR DRIZZLE ALONG/BEHIND THE FRONT...THEN DRY ADVECTION REALLY KICKS IN. VIS/IR SATELLITE SHOW CLEAR SKIES ACROSS CENTRAL WISCONSIN AND NORTHERN ILLINOIS. SOME MOISTURE TRYING TO WRAP IN FROM NORTHERN MINNESOTA...BUT THAT WILL NOT AFFECT US UNTIL TONIGHT. FOR THIS AFTERNOON AND EVENING...12Z ETA/RUC INDICATE STRONG SUBSIDENCE AND DRYING ACROSS LOWER MICHIGAN. FORECAST SOUNDINGS INCREASE LOW-LEVEL DEWPOINT DEPRESSIONS /BELOW 850-900MB INVERSION/ TO 5C-8C...WHILE MID-LEVEL DEWPOINT DEPRESSIONS /GENERALLY 700MB-500MB/ CLIMB TO 40C BY 00Z THIS EVENING PER BOTH RUC/ETA. WITH SOME LINGERING LOW-LEVEL MOISTURE...MAY SEE CU FILL IN AFTER SKIES CLEAR OUT...WHICH IS ALREADY BEGINNING TO HAPPEN ACROSS WISCONSIN/IOWA. WILL HOLD ON TO THE MOSTLY CLOUDY EAST/BECOMING PARTLY SUNNY NORTHWEST...WITH MOSTLY CLEAR OR CLEARING OVERNIGHT. MORNING RAOBS SHOW A DECENT THERMAL GRADIENT ASSOCIATED WITH THE COLD FRONT...WITH 850MB TEMPERATURES DROPPING FROM 11-12C AT DTX/ILX/APX TO 7C AT GRB/DVN...AND DOWN TO -4C AT MPX. MAIN THERMAL TROUGH MOVES OVER LOWER MICHIGAN TONIGHT...BUT WITH COLD ADVECTION CONTINUING THROUGH THE DAY. CURRENT TEMPERATURES ACROSS THE CWA ARE GENERALLY IN THE MID 60S...BUT STATIONS ACROSS WESTERN LOWER HAVE ALREADY DROPPED INTO THE 50S...WHICH IS ALSO SEEN ACROSS WISCONSIN. WILL CONTINUE THE FALLING TEMPERATURES FOR TODAY. BRAVENDER FULL MORNING DISCUSSION... AN UPPER LEVEL TROUGH MOVING ACROSS THE UPPER MISSISSIPPI VALLEY HAS AN ASSOCIATED COLD FRONT EXTENDING ACROSS EXTREME EASTERN WISCONSIN INTO SE MISSOURI. AREA RADAR DATA SHOWS AN AREA OF SHOWERS AND THUNDERSTORMS EXTENDING ALONG AND JUST AHEAD OF THE SURFACE COLD FRONT. THE PRECIPITATION HAS DEVELOPED ALONG A REGION OF DEEP FRONTOGENETICAL FORCING WITHIN THE ENTRANCE REGION OF AN UPPER LEVEL SPEED MAX CENTERED OVER NORTHERN ONTARIO. 00Z SOUNDING ANALYSES ACROSS THE MISSISSIPPI VALLEY...AHEAD OF THE FRONT...HAD AMPLE MOISTURE FROM THE SURFACE TO 500MB TO SUPPORT WIDESPREAD PRECIPITATION ALONG THE FRONT. PRECIPITABLE WATER VALUES OF 1.5 INCHES ALSO EXTENDING INTO NORTHERN ILLINOIS. THIS AREA OF PRECIPITATION WILL WORK ITS WAY ACROSS SOUTHEAST LOWER MICHIGAN THIS MORNING AS THE COLD FRONT PUSHES EAST. BASED ON AREAL COVERAGE OF THE SHOWERS ON UPSTREAM RADARS...CATEGORICAL WORDING STILL LOOKS WARRANTED. SOME DRYER AIR IN THE MID LEVELS OVER THE EASTERN LAKES REGION RESULTING FROM SUBSIDENCE WITHIN THE MID LEVEL RIDGE AXIS NOW DEAMPLIFYING OVER THE EASTERN LAKES SEEMS TO BE CONFINING THE MORE WIDESPREAD SHOWERS CLOSER TO THE SURFACE COLD FRONT. THIS SHOULD LIMIT THE DURATION OF THE MORE WIDESPREAD RAINFALL TO AN HOUR OR TWO AS IT MOVES ACROSS THE AREA THIS MORNING. THE ETA SOLUTION IS A COUPLE HOURS SLOWER AT BRINGING THE SURFACE FRONT THROUGH TODAY IN COMPARISON TO THE GFS. BASED ON THE CURRENT POSITION OF THE FRONT AND THE LATEST RUC SOLUTION...THE SLIGHTLY SLOWER ETA SOLUTION SEEMS MORE REASONABLE. BASED ON THIS...THE FRONT SHOULD MOVE INTO THE WESTERN PORTIONS OF THE FORECAST AREA AROUND 12Z AND EXIT TO THE EAST OF PORT HURON AROUND 18Z. CAPE COMPUTED FROM 925MB ON MODEL SOUNDINGS SHOWS A COUPLE HUNDRED JULES THIS MORNING...WITH SHOWALTER INDICES PROGGED AROUND -1C. THIS WILL CERTAINLY SUPPORT THUNDER. SEVERE THREAT STILL LOOKS TO BE NON EXISTENT THOUGH AS INSTABILITY WILL JUST BE TOO WEAK. STRONG SUBSIDENCE/ISENTROPIC DESCENT WILL WORK INTO THE AREA IN THE WAKE OF THE SURFACE COLD FRONT. 850MB TEMPS WILL ALSO FALL NEARLY 10 DEGREES LATE THIS AFTERNOON AND EVENING. THE STRONG COLD AIR ADVECTION WILL BOOST MIXING HEIGHTS...WHICH SHOULD LEAD TO A BRIEF PERIOD OF GUSTY WINDS AT THE ONSET OF COLD AIR ADVECTION. ETA MODEL SOUNDINGS INDICATE MOISTURE IN THE 2K TO 4K FT LAYER WILL REMAIN TRAPPED UNDER A STRENGTHENING SUBSIDENCE INVERSION THROUGH MUCH OF THE NIGHT. MOS GUIDANCE HOWEVER SUGGESTS A RAPID CLEARING FROM WEST TO EAST LATE THIS AFTERNOON THROUGH EARLY EVENING. WITH SATELLITE DATA SHOWING CLEAR SKIES ACROSS IOWA AND SOUTHERN MINNESOTA...I WILL LEAN THE FORECAST TOWARD MOS AND HAVE SKIES CLEAR DURING THE EVENING. THE SURFACE PRESSURE GRADIENT OVER SOUTHEAST MICHIGAN SHOULD PREVENT THE BOUNDARY LAYER FROM DECOUPLING. I WILL THUS KEEP FCST LOWS NEAR GUIDANCE (UPPER 30S NORTH TO LOWER 40S SOUTH) AND NOT MENTION FROST. SURFACE HIGH PRESSURE AND VERY DRY AIR STILL LOOKS POISED TO PUSH INTO THE REGION BY WEDNESDAY. THIS WILL SUPPORT COOL AND DRY CONDITIONS THROUGH MID WEEK...WHICH THE CURRENT ZONE AND GRIDDED FORECAST HAS COVERED WELL. THERE STILL LOOKS TO BE A FROST POTENTIAL ACROSS THE NORTH WEDNESDAY NIGHT WHERE THE SURFACE PRESSURE GRADIENT WILL BE A LITTLE WEAKER. WITH THE ETA INDICATING SOME HIGH CLOUDS MOVING IN AND SHOWING 925MB WINDS OF 20KTS OVER THE ENTIRE AREA THROUGH THE NIGHT...I WILL KEEP FCST MIN TEMPS IN THE MID TO UPPER 30S ACROSS THE NORTH AND REFRAIN FROM MENTIONING FROST AT THIS TIME EXCEPT FOR CLIMATOLOGICALLY FAVORED AREAS IN THE NORTHERN THUMB. FROST POTENTIAL WEDNESDAY NIGHT WILL CONTINUE TO BE MONITORED THE NEXT SEVERAL FORECAST PERIODS. THE GFS HAS TRENDING FASTER AT DEVELOPING A CUT OFF UPPER LOW OVER THE GREAT LAKES BY THE END OF THE WEEK. THE GFS ALSO BRINGS A POTENT SHORT WAVE AND DEEP MOISTURE INTO THE AREA ON FRIDAY. WITH THE UKMET AND TO A GREATER DEGREE THE ETA MUCH WEAKER AND SLOWER WITH THE DEVELOPMENT OF THE UPPER TROUGH...I WILL NOT ADD PRECIP TO FRIDAY AT THIS TIME. .DTX...NONE. $$ CONSIDINE EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE BINGHAMTON NY 930 AM EDT TUE MAY 20 2003 UPDATE... AREA OF SHOWERS AHEAD OF A WEAK VORT MAX CROSSING LAKE ERIE AND EASTERN OHIO POSE A SMALL CHC OF SHOWERS FOR THE CNTRL SRN TIER AND ERN FINGER LAKES LATE THIS AFTERNOON...AFT 4 PM. RUC40 AND 06Z ETA ARE A BIT MORE UNSTABLE THAN GUIDANCE YDY...AS STRIPE OF HIGHER DWPTS ADVECTS IN. TEMPS WILL REACH THE UPPER 70S...BUT THERE CONTINUES TO BE A SUBSIDENCE CAP BTWN 800-700 MB. ELEVATED INSTAB NOT IMPRESSIVE AND BEST UL FORCING SHEARS AWAY TO OUR NORTH...SO AT THIS POINT WILL JUST INCLUDE CHC FEW SHRA AND NO THUNDER FOR ZONES WEST OF AN ELM-AUBURN LINE. ANY SHOWERS LOOK TO BE SPARSE AND QUICK HITTING TONIGHT...LIKELY OVER BY DAYBREAK. MAY HAVE TO SPEED THINGS UP A BIT OVERNIGHT...BUT WILL DO THAT AFT 12Z GUIDANCE DIGESTED. BREWSTER PREVIOUS DISCUSSION... DEEPENING TROF OVER DAKOTAS WITH ASSOCIATED COLD FRONT MOVING INTO WI. THUNDERSTORMS BREAKING OUT OVER N IL AND WI INVOF SHORT WAVE RIDING OVER SHARP TEMP GRADIENT. MEANWHILE FAIR WEATHER RIDGE IS POSITIONED OVER MUCH OF EASTERN US WITH WARM DRY AIR FLOWING FROM TX TO MIDATLANTIC REGION. INITIAL THOUGHT THIS AM IS AVN IS SLIGHTLY BETTER HANDLING THE DIGGING TROF TO THE WEST...BUT IS A BIT FAST WITH ITS EASTWARD PROGRESSION. FAVOR AVN PARAMETERS BUT SLOWER GIVEN THE STRENGTH OF THE EASTERN RIDGE AND THE HIGH 850MB TD DEPRESSIONS. TUESDAY LOOKS LIKE ANOTHER WARM SPRING DAY WITH ONLY CI TO DEAL WITH AS IT RIDES DOWN THE RIDGE. COLD FRONT APPROACHES TUESDAY NIGHT AND SPREADS SHOWERS ACROSS FA. LACK OF SIG SHORT WAVE LEADS ME TO BELIEVE THUNDER WILL NOT BE A THREAT. INSTABILITY IS MINIMAL. TROF SWINGS NORTHEASTWARD AND MUCH OF EASTERN US GOES ZONAL THEREAFTER. LOOKS LIKE RESIDUAL SHOWERS EARLY WED BUT WE DRY OUT AS DAY PROGRESSES. FAVOR WARMER/LOWER POP SOLN OF MAV GUIDANCE. GROWING AGREEMENT AMONG MODELS FOR A DRY THURSDAY. WILL UPDATE THIS DAY BUT LEAVE REMAINDER OF EXTENDED TO NEXT SHIFT WHEN NEW MRF IS AVAILABLE. .BGM...NONE. PADAVONA ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 135 PM EDT TUE MAY 20 2003 CURRENTLY: WATER VAPOR IMAGERY/RUC H5 COMPOSITE SHOWS FORMER MID/UPPER LOW NOW AN OPEN WAVE OVER THE CENTRAL GULF OF MEXICO. CONVECTION ASSOCIATED W/ THIS FEATURE IS DISORGANIZED. COOL WEDGE STILL EVIDENT ON SURFACE ANALYSIS W/ LEADING EDGE OF E-NELY LOW-LEVEL FLOW I.E. "BACKDOOR" FRONT FROM NE FL INTO SW AL. ABOUT A 10-DEGREE TEMP/DEW POINT SPREAD ACROSS THE CWFA. VISIBLE IMAGERY SHOWS BREAKS IN LOW CEILINGS N OF BOUNDARY. CLOUDS ERODING OVER ERN GA AS DRIER AIR ADVECTING SWWD. NEAREST CONVECTION WAS ISOLATED OVER OUR OFFSHORE WATERS. MODELS: MODELS MAINTAIN A GOOD HANDLE ON THE DEMISE OF THE H5 LOW OVER THE CENTRAL GULF OF MEXICO & DEVELOPMENT OF MEAN TROUGH OVER THE ERN CONUS AFT 36 HRS...WHICH WILL ALLOW SEVERAL VORT MAXIMA TO TRANSLATE ESE INTO THE SERN CONUS. BACKDOOR FRONT IS PROGGED TO MOVE LITTLE...BISECTING THE CWFA FROM NW TO SE TONIGHT. THIS BOUNDARY WILL LIFT N OF CWFA ON WED AS CYCLOGENESIS OCCURS ALONG AN APPROACHING COLD FRONT OVER SW AL. GFS PLACEMENT OF LOW IS SLIGHT E OF ETA'S POSITION & IS DEEPER. THE LOW MOVES SLOWLY EWD...INVOF DHN BY 12Z THU & INVOF VLD BY 00Z FRI. MODEL TIME-HEIGHT X-SECTIONS SHOW PERIOD OF MAX LIFT/DEEP LAYER MOISTURE BETWEEN 18Z WED & 18Z THU. PWAT VALUES STAY RATHER HIGH (1.5-2.0")...SO LOCALLY HEAVY RAINFALL IS A GOOD POSSIBILITY. SEVERE THREAT APPEARS LOW GIVEN MINIMAL INSOLATION...WEAK SHEAR AND LACK OF DRY AIR ALOFT. COLD FRONT PROGGED TO MOVE THRU CWFA THU NIGHT...FOLLOWED BY SIGNIFICANT DRYING OF MID/UPPER LEVELS ON FRI. FORECAST: WILL ADVERTISE SCATTERED POPS ALL BUT FAR SE TONIGHT. HIGH LIKELY POPS A SURE BET OVER ALL BUT FAR SE WED/WED NIGHT. ON THU...SCATTERED W/LOW LIKELY POPS E. POPS TAPER OFF TO SLIGHT CHANCE W/CHANCE E THU NIGHT. NIL POPS FOR FRI. CLOUD COVER & PCPN SHOULD KEEP TEMPS IN CHECK...SLIGHTLY BELOW SEASONAL NORMALS. MARINE: WINDS GRADUALLY VEER FROM ELY TO SLY DURING NEXT 24 HRS. WINDS INCREASE A TAD...BUT STAY BELOW CRITERIA AS LOW OVER AL MOVES INTO GA & COLD FRONT ENTERS WRN LEGS THU AFTN. WINDS BECOME NWLY AFTER FROPA THU NIGHT/EARLY FRI MORNING. NLY WINDS BACK AROUND TO THE W/SW AHEAD OF NEXT FRONT APPROACHING FROM THE N ON SUN. FIRE WEATHER: NO REQUIREMENTS. EXTENDED (SAT-TUE): HIGHLY AMPLIFIED PATTERN WILL DOMINATE THE LOWER 48 W/ MID/UPPER LOW PARKED OVER THE OH VALLEY/GREAT LAKES & UPSTREAM RIDGE OVER THE PLAINS. THIS WILL DRIVE ANOTHER FRONT SEWD TOWARD THE CWFA SUN. THIS FRONT SLOWS ITS FORWARD MOTION MEMORIAL DAY & STALLS NEAR OUR COASTAL WATERS ON TUE AS MAIN DYNAMICS LIFT WELL TO THE NE & H5 FLOW PARALLELS THE FRONT. MOISTURE W/ THIS FRONT LOOKS MARGINAL & WILL INSERT SLIGHT CHANCE POPS...MAINLY DURING THE AFTN. PRELIMINARY POINT TEMPS/POPS: TLH 68 84 69 83 / 30 60 70 60 PFN 70 82 70 82 / 40 60 70 50 DHN 68 80 67 81 / 50 70 70 40 ABY 66 81 67 81 / 30 60 70 60 VLD 67 83 69 82 / 30 60 70 60 CTY 67 84 69 83 / 20 40 50 60 .TLH WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. $$ MAJ fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 300 PM CDT TUE MAY 20 2003 COLD FRONT CONTINUES TO MAKE DECENT PROGRESS ACROSS EAST TX WITH TEMPS DROPPING AROUND 10 DEGREES WITHIN AN HOUR OF FRONTAL PASSAGE. FRONT WILL CONTINUE ITS SOUTHEAST PUSH AND ENTER NORTHWEST ZONES EARLY THIS EVENING AND THEN PUSH OFFSHORE OVERNIGHT. AS FAR AS POPS... LITTLE IN THE WAY OF CONVERGENCE AS NORTH WINDS EVIDENT AHEAD OF THE FRONT AND STRONG CAP NOTED AROUND 700MB HELPING TO SQUASH PRECIP. MCS OVER NORTH TX FALLING APART BUT ASSOCIATED SHORTWAVE PROGGED BY MESOETA AND RUC TO MOVE INTO SOUTHEAST TX THIS EVENING ALONG WITH FRONT. THIS SHOULD HELP ERODE THE CAPE ENOUGH TO AT LEAST PRODUCE WIDELY SCATTERED TSTMS. 850MB FRONT WILL MOVE OFF THE COAST THRU WEDNESDAY AND WILL COMBINE WITH WEAK SHORTWAVE TO LEAVE SLIGHT CHANCE OF POPS IN FORECAST FOR WEDNESDAY. DRIER AND COOLER AIR WILL FILTER INTO THE REGION AND STICK AROUND THROUGH SATURDAY. WILL INTRODUCE SLIGHT CHANCE OF POPS SUNDAY THROUGH TUESDAY WITH INCREASING SOUTHWEST FLOW ALOFT AND RETURN OF ONSHORE FLOW AT THE SURFACE. .PRELIMINARY POINT TEMPS/POPS... KLCH 67 82 64 85 / 30 20 10 00 KBPT 67 82 65 85 / 30 20 10 00 KAEX 64 79 60 82 / 30 20 10 00 KLFT 67 79 64 85 / 30 30 10 00 .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. $$ 99 la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 220 PM EDT TUE MAY 20 2003 SHOWERS AHEAD OF AN ADVANCING COLD FRONT ARE IN THE PROCESS OF WORKING ACROSS THE WESTERN COUNTIES AT PRESSTIME...ALTHOUGH THE DRIER AIRMASS IN PLACE IS ERODING ITS LEADING EDGE. FURTHER TO THE WEST... A COLD FRONT HAS PUSHED THROUGH DTX AND IS NOW SET TO CROSS LAKE ERIE AND SOUTHERN ONTARIO. THE AIRMASS BETWEEN THE PRE FRONTAL SHOWERS AND THE ACTUAL SFC FRONT IS ONLY MARGINALLY UNSTABLE WITH LI'S OF ZERO TO +2...BUT STRONG MOISTURE CONVERGENCE WILL BE ENOUGH TO PRODUCE LIKELY TO CAT POPS FOR -SHRA. CURRENT MSAS ANALYSES AND RUC40 FORECASTS SHOW THIS CONVERGENCE RATHER WELL...WITH SOME UPPER LEVEL DIFFLUENCE HELPING TO FURTHER DESTABLIZE THINGS. TREND OF THE U.S. AND CANADIAN RADARS IS AN INCREASE IN COVERAGE AREA OF THE ACTIVITY. WILL THUS GO WITH HIGH LIKELY POPS FOR THE BULK OF THE REGION THIS EVENING. THERE IS A SHARP CUTOFF TO THE CLOUD COVER BEHIND THE FRONT...WITH CLEAR SKIES BEING OBSERVED FROM LK MICHIGAN WESTWARD. THIS ALIGNS VERY WELL WITH -VV RUC40 FORECASTS. THIS CLEARING SHOULD WORK ACROSS WESTERN NEW YORK AFTER MIDNIGHT. FOR WEDNESDAY...EXPANSIVE HIGH PRESSURE OVER THE UPPER MISSISSIPPI VALLEY WILL BUILD ACROSS THE GREAT LAKES AND OUR FORECAST AREA. DEEP DRY AIR AND PLENTY OF SUBSIDENCE SHOULD PROVIDE US WITH A SUN FILLED DAY ALTHOUGH H8 TEMPS OF +2 TO +4 WILL KEEP MAX TEMPS A LITTLE BELOW NORMAL. THE SFC HIGH WILL THEN SET UP SHOP OVER EASTERN CANADA FOR WEDNESDAY NIGHT INTO EARLY FRIDAY. AS A RESULT...ANOTHER SPELL OF GENERALLY COOL AND DRY WEATHER CAN BE EXPECTED. THIS TIME PERIOD SHOULD BE TAKEN ADVANTAGE OF THOUGH BECAUSE A LOOK FURETHER DOWN THE ROAD SHOWS THE POTENTIAL FOR A PROLONGED PERIOD OF UNSETTLED WEATHER FROM FRIDAY THROUGH THE UPCOMING HOLIDAY WEEKEND. IN FACT...IT COULD GET DOWNRIGHT UGLY ACROSS THE REGION SATURDAY INTO MONDAY WITH FREQUENT BOUTS OF RAIN AND TEMPERATURES AVERAGING BELOW NORMAL. .BUF...NONE. RSH ny