AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LITTLE ROCK AR 250 PM CST WED MAR 29 2000 RUC SHOWING MORE PVA MOVING THROUGH WESTERN AR THRU 06Z WITH SCATTERED THUNDERSTORMS CONTINUING IN NORTH AR AND DEVELOPING IN SOUTH AR THRU THIS EVENING. ATMOSPHERE CONTINUES VERY UNSTABLE IN THE SOUTH PART OF THE STATE ALONG THE FRONTAL BOUNDARY...WHICH EXTENDS ALONG THE AR/LA BORDER...MAY SEE SVR TSTMS IN THAT PART OF THE STATE THIS EVENING. TEMPS WILL CONTINUE ON THE COOL SIDE TONIGHT THRU THURSDAY WITH A SLOW WARMING TREND FRIDAY. ANOTHER FRONT WILL GIVE SOME CHANCE OF RAIN TO AR OVER THE WEEKEND. .LIT...NONE. ar AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PEACHTREE CITY GA 330 PM EST WED MAR 29 2000 THE NGM AND ETA MODELS BOTH INDICATE SIGNIFICANT MOISTURE ONLY TO ABOUT 700 MB WHILE THE AVN HAS MUCH DEEPER MOISTURE. THUS WIDE DIVERGENCE IN POPS OVER THE CWFA. OVERALL SCENARIO IS CONSISTENT AMONG MODELS. FRONT NEARLY STATIONARY JUST SOUTH OF THE CWFA...FROM NEAR STATESBORO TO AMERICUS TO TROY, AL. LATEST RUC SHOWS THE FRONT SHOULD COME NORTHWARD A LITTLE OVERNIGHT TO JUST NORTH OF THE FALL LINE AND THEN MOST OF THE AREA SHOULD BE IN THE WARM SECTOR LATE TOMORROW MORNING. MOST OF THE SEVERE WEATHER OVERNIGHT SHOULD REMAIN TO OUR SOUTH AND WEST. HOWEVER THERE IS A RISK OVER SOUTHERN PORTIONS OF OUR CWFA ON THURSDAY. CLEARING THURSDAY NIGHT AND MOSTLY SUNNY FRIDAY AS DRIER AIR MOVES IN. AIR OF PACIFIC ORIGIN SO NOT MUCH OF A COOLING TREND. FOR POPS AM LEANING TOWARD THE HIGHER AVN NUMBERS. THIS WOULD REMAIN CONSISTENT WITH THE CURRENT FORECAST. THIS WOULD ALSO BE MORE CONSISTENT WITH THE SURROUNDING WFO'S. ALSO THE LATEST RUC SHOWS A GOOD BIT OF MOISTURE ACROSS NORTHERN THIRD OF STATE BY 06Z WITH SOME OVERRUNNING NORTH OF THE FRONT. ATL 53/69 48/72 8610 AHN 50/69 47/71 8710 RMG 45/66 44/72 8710 CSG 58/78 50/74 6500 MCN 56/77 49/74 7600 .ATL...NONE. 26 ga AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE LINCOLN IL 905 PM CST WED MAR 29 2000 GOING FORECAST LOOKS ON TRACK THIS EVENING. IR SATELLITE LOOP INDICATING MID AND HIGH LVL CLOUD SHIELD ONLY EXTDG INTO THE FAR SERN PTN OF THE FCST AREA. 00Z RUC CONTINUING TO INDICATE PRECIP TO STAY SOUTH OF ILX COUNTIES THIS EVENING. .ILX... IL...NONE. SMITH il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 345 PM EST WED MAR 29 2000 TIGHT GRADIENT REMAINS OVER SOUTHEAST MICHIGAN WITH DEEP LOW OVER SOUTHERN QUEBEC MAINTAINING CYCLONIC FLOW AT THE SURFACE. THE LOW WILL GRADUALLY PULL OFF TO THE NORTHEAST OVER THE NEXT 24 TO 48 HOURS...BUT THE PROCESS WILL BE RATHER SLOW WITH NO REALLY STRONG UPPER FEATURES COMING FROM THE WEST TO PUSH IT ALONG IN THE SHORT-TERM. AS A RESULT...DRY CONDITIONS WILL PREVAIL. FOR TONIGHT...THE OVERALL DIURNAL NATURE OF THE CU/SC ON SATELLITE IMAGERY LENDS SUPPORT FOR SOME DIMINISHING OF THE CLOUDINESS WITH SUNSET. THE ETA MODEL SOUNDINGS WOULD PROVIDE FOR ENOUGH MOISTURE TO KEEP CLOUDS FOR MUCH OF THE NIGHT AND INTO THURSDAY MORNING... WHEREAS THE NGM AND AVN...AND EVEN THE LATE MORNING AND EARLY AFTERNOON RUNS OF THE RUC...EXTRAPOLATE DIMINISHED BOUNDARY LAYER MOISTURE OVER SOUTHEAST MICHIGAN. THINK THE RUC MAY BE A LITTLE FAST WITH THE DRYING THIS EVENING...BUT OVERALL...EXPECT A GRADUAL REDUCTION IN THE CLOUDS TONIGHT. HOWEVER...WILL KEEP HURON COUNTY PARTLY CLOUDY. BOTH THE ETA AND AVN BRING AN 850MB THERMAL TROUGH SOUTH ACROSS LAKE HURON OVERNIGHT WITH TEMPERATURES AT THAT LEVEL FALLING TO AS COLD AS MINUS 9 DEGREES CELSIUS. THE 1000MB-850MB MEAN FLOW TENDS TO BE NORTHWEST THROUGHOUT THE PERIOD...BUT A SHIFT TO THE NNW IS APPARENT ESPECIALLY ON THE NGM MODEL SOUNDING IN THE WAKE OF AN UPPER SHORTWAVE THAT PUSHES ACROSS LOWER MICHIGAN FROM ONTARIO LATE TONIGHT. NO PRECIPITATION EXPECTED WITH THIS WAVE IN THE OVERALL DRY AIR...BUT MAY SUPPORT SOME CLOUDS WITH THE COLD AIR OVER LAKE HURON SPILLING INTO PARTS OF EASTERN HURON COUNTY. LATEST VISIBLE CLOUDS HAVE SHOWN SOME CLOUDS DEVELOPING JUST NORTHEAST OF THE MOUTH OF SAGINAW BAY...MOVING SOUTHEAST WITH THE MEAN FLOW... WELL AHEAD OF THE UPPER WAVE AND THE THRUST OF THE COLDER AIR. A FEW CLOUDS ANTICIPATED FOR THE DAY THURSDAY...BUT SHOULD BE ENOUGH SUN TO WARRANT A MOSTLY SUNNY FORECAST. THE ETA...WITH ITS ABUNDANCE OF LOW-LEVEL MOISTURE...WOULD PROVIDE FOR A GOOD CU FIELD OVER SOUTHEAST MICHIGAN FOR THE AFTERNOON. LOOKING WELL UPSTREAM... NOT MUCH CU TO BE FOUND...AND SOME OF THE LOW-LEVEL MOISTURE PROGS FROM THE MODELS WOULD SUPPORT MORE CU JUST TO OUR EAST. WILL KEEP MAXES JUST A HAIR BELOW GUIDANCE AS THE THICKNESSES DO NOT INCREASE MUCH AND THE 850MB THERMAL TROUGH WILL BE SLOW TO RETREAT EASTWARD. HIGH PRESSURE CONTINUES TO BUILD OVER THE STATE AT THE SURFACE THURSDAY NIGHT...GIVING LIGHT WINDS AND COOL TEMPERATURES. THE AVN...WHICH IS FASTER THAN THE ETA LATE IN THE SHORT RANGE...STARTS TO USHER IN 300MB MOISTURE OVER LOWER MICHIGAN BY 12Z FRIDAY. HIGH AND MID LEVEL CLOUDS...WITH HIGHER VALUES OF 500MB MOISTURE AS WELL...MAY SNEAK INTO SOUTHEAST MICHIGAN BY FRIDAY MORNING. THINK THE TIMING OF THE AVN MAY BE A LITTLE FAST RELATIVE T0 THE ETA ON THE WEAK UPPER WAVE AND SURFACE FRONT MOVING OVER THE NORTHERN PLAINS LATE IN THE WEEK...SINCE THE CYCLONE OVER EASTERN CANADA IS NOT GOING TO FADE AWAY QUICKLY AND IT WILL BE DIFFICULT AT FIRST FOR SYSTEMS TO CHUG EAST WITH THAT BARRIER. ETA...STILL...BRINGS A HINT OF 300MB MOISTURE ACROSS SOUTHWEST MICHIGAN BY SUNRISE FRIDAY...AND WILL FORECAST PARTLY SUNNY FOR FRIDAY AT THE MOMENT...BUT COULD SEE MORE SUN IN THE FORECAST IF THE SLOWER ETA REALLY PANS OUT. LONG-TERM MODEL DISAGREEMENTS ARE THE FLAVOR OF THE EXTENDED. COMPARING THE 00Z AVN WITH THE 00Z MRF WOULD SHOW THAT THE MRF IS SLIGHTLY FAST WITH ITS PROGRESSION OF FEATURES OVER THE NEXT SEVERAL DAYS...WITH THE 00Z AVN UPPER-LEVEL PATTERN A BIT MORE AMPLIFIED THAN THE MRF. THE ETAXX FOLLOWS THE MRF IN GENERAL WITH JUST A TOUCH SLOWER PROGRESSION...AND A WEAK COLD FRONT...OR BETTER YET...WEAK SURFACE TROUGH...MOVING THROUGH SOUTHEAST MICHIGAN LATE SATURDAY. SHORTWAVE RIDGING ALOFT MOVES IN BEHIND THE WEAK SURFACE FEATURE BEFORE DEEPENING LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS. ALL OF THIS IF YOU BELIEVE THE MRF/ETAXX. THE CANADIAN/NOGAPS BLEND REVERSES THINGS...AND BY THE FIRST PART OF THE WORK WEEK THERE IS A BUILDING RIDGE OVER THE WESTERN STATES...NORTH OF A CUTOFF LOW OVER OLD MEXICO...AND AN UPPER-LEVEL TROUGH OVER THE EASTERN THIRD OF THE NATION. VIEWING THE ENSEMBLES WOULD TEND TO SUPPORT THE CONCLUSION OF THE ETAXX AND MRF...BUT THE 12Z AVN HAS TRENDED TOWARD A STRONGER WAVE IN THE SOUTHWEST STATES...AND A FASTER MOVEMENT OF THE SURFACE FEATURES MOVING ACROSS THE NORTHERN GREAT LAKES...FLATTING THE RIDGE FASTER IN THE SHORT-TERM. WHEW. BASICALLY...ANY PRECIPITATION ON SATURDAY IS A BIG QUESTION MARK AT THE MOMENT. LITTLE ENERGY ALOFT WITH THE WEAKENING SURFACE FEATURE...ALONG WITH LITTLE MOISTURE DUE TO A SURFACE RIDGE OVER THE SOUTHEAST STATES HELPING TO HOLD DEEPER MOISTURE AT BAY...WILL KEEP RAIN CHANCES TO A MINIMUM. OF COURSE...THE CANADIAN IS MUCH STRONGER WITH THE UPPER-LEVEL ENERGY...AND SINCE RAIN IS IN THE FORECAST NOW...WILL NOT WAFFLE TO REMOVE IT. AS THE SURFACE RIDGE OVER THE SOUTHEAST STATES WEAKENS AND MOVES EAST...THE GULF WILL OPEN AND THE START OF THE WORK WEEK LOOKS TO BE AN UNSETTLED ONE. A STRONG LOW PRESSURE SYSTEM OVER THE PLAINS WILL HELP TO USHER IN RAIN WITH A WARM FRONT MOVING NORTH ACROSS SOUTHERN MICHIGAN LATE SUNDAY...THEN A GOOD COLD FRONT WILL SWEEP BY LATE MONDAY WITH COLDER TEMPERATURES AND BLUSTERY CONDITIONS BEHIND IT. MRF FORECASTS THE THERMAL RIDGE TO BE ALL THE WAY INTO THE EASTERN GREAT LAKES BY 00Z TUESDAY...BUT WITH THE STRENGTH OF THE FRONT AND THE POTENTIAL INSTABILITY ON ETAXX SOUNDINGS WITH JUST A SLIGHT BIT OF COOLING ALOFT...THERE COULD BE SOME THUNDER. THOUGH THE MRF WOULD SUGGEST THICKNESSES LOW ENOUGH TO SUPPORT SOME SNOW FOR A TIME EARLY TUESDAY...THIS IS THE PERIOD THAT APPEARS THE DRIEST AT THE MOMENT...AND WILL NOT FORECAST ANY OF THAT FROZEN STUFF IN THIS EXTENDED. .DTX...NONE. DJF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 300 PM EST WED MAR 29 2000 ...BECOMING MOSTLY CLEAR TONIGHT THEN PARTLY CLOUDY WITH CU THU... MOST OF SC ON THE CYCLONIC SIDE OF THE POLAR JET AT 18Z. AT 18Z THE POLAR JET AXIS WAS FROM ERN MN TO SW OHIO TO WV. THIS JET SEGMENT WILL MOVE OUT OF PICTURE TONIGHT AS ASSOCIATED VORT/SHTWV MOVES WITH IT. NEXT SHTWV/ASSOCIATED POLAR JET SEGMENT WILL MOVE SWD IN NRN LWR MI AFT 06Z BUT THAT WILL BE NORTH AND EAST OF OUR CWA. ALSO RUC AND NGM LOW LEVEL RH FIELDS BETTER MATCH OF THE SC OVER MI AND WI THAN DOES THE ETA 925 RH. IN ANY EVENT... ALL MODELS SHOW 850 RH PLUNGING THIS EVENING BEHIND THAT VORT MAX. SO THE COMBINATION OF THE LOW LEVEL ANTICYCLONIC FLOW...FALLING INVERSION LEVEL... AND DECREASE MEAN RH 1000 TO 850 WILL ALLOW CLEARING OCCUR TONIGHT. THIS WILL ALLOW TEMPS TO INTO THE LOWER TO MID 20S AWAY FROM LAKE AND NEAR 30 BY THE LAKE SHORE. ON THURSDAY... HIGH PRESSURE MOVES IN AT SURFACE AND UPPER LEVEL RIDGE MOVES IN BEHIND DEPARTING STORM OVER EASTERN CANADA. STRONG SUBSIDENCE WILL KEEP SKIES CLEAR ABOVE 5000 FT THROUGH THURSDAY NIGHT. ENOUGH INSTABILITY (CU PROCEDURE AND USING MODEL SOUNDINGS) TO GET AFTERNOON CU. SO WILL FCST MOSTLY SUNNY MORNING AND PARTLY CLOUDY IN THE AFTERNOON. 1000/850 THICKNESS ACTUALLY LOWER THAN TODAY FOR THURSDAY... BUT SIGNIFICANTLY MORE SUNSHINE. ALL HIGH TEMP ROUTINES SUGGEST NEAR 50 SO WILL GO WITH THAT. LAKE BREEZE MAY KEEP TEMPS IN MID TO UPPER 40S NEAR LK MICHIGAN...W OF US-31...BUT WITH NORTH TO NORTH NORTHWEST WIND 925 MB TO 850 MB... LIMITED INLAND EFFECT. DUE TO SKIES WILL CLEAR AGAIN THURSDAY NIGHT AND WINDS WILL BE NEAR CALM... SO EXPECT TEMPS IN 20S MOSTLY. FRIDAY WILL SEE NEXT UPSTREAM SHTWV MOVE INTO AREA FROM WEST BUT THIS IS MOISTURE STARVED AND MOST OF DYNAMICS WELL NORTH OF SW MI... SO WILL GO WITH PARTLY CLOUDY SKIES AND HIGHS MID TO UPPER 50S. EXTENDED DISCUSSION INTERESTING WX PATTERN SHAPING UP FOR THE WEEKEND. WEAK SHORT WAVE RIDGING WILL MOVE OUT OF THE REGION FRIDAY NIGHT AND BE REPLACED WITH A SHORT WAVE MOVG EAST ACROSS THE NRN TIER OF STATES. THAT SHORT WAVE TROF WILL BE OVER THE LAKES ON SATURDAY. WILL KEEP THE CHANCE OF SHOWERS GOING FRIDAY NIGHT AND SATURDAY. SUNDAY WILL BE THE BRIGHTEST DAY WITH SUNSHINE AS UPR RIDGING MOVES INTO THE LAKES. WILL CLOUD THINGS UP ON MONDAY AGAIN AS A LARGE UPR TROF OVER THE WRN STATES BEGINS EJECTING SHORTWAVES NE TOWARD THE LAKES AND ISENTROPIC LIFT AHEAD OF THE SFC LOW MOVES INTO THE REGION. .GRR...NONE. WDM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1030 AM EST WED MAR 29 2000 ...PARTIAL CLEARING BY LATE AFTERNOON... 500 SHTWV COMBINED WITH POCKET OF -8C 850 AIR OVER WI AT 12Z WILL ROTATE THROUGH CWA BY EARLY AFTERNOON. GRB SOUNDING... WHICH IS NEAR THE SHTWV AT 12Z...SHOWED CONSIDERABLE DRY AIR ABOVE 4000 FT. MEANWHILE...THE DTX SOUNDING DID NOT SHOW THE SUBSIDENCE INVERSION LIKE GRB DID AND WAS CONSIDERABLY MORE MOIST THROUGH 300 MB THAN GRB. SINCE THE SHTWV IS FCST TO ROTATE THROUGH THE CWA BY 18Z AND SINCE THERE ARE NO MID OR HIGH CLOUDS SHOWN ON THE IR IMAGES ASSOCIATED WITH THIS SHTWV... BELIEVE LATE MARCH SUN WILL ALLOW THE RUC SOUNDING TO VERIFY BETTER THAN THE ETA SOUNDINGS AND THAT IMPLIES CLEARING SKIES THIS AFTERNOON. THE RADAR DOES SHOW SPRINKLES OVER THE PARTS OF THE GRR CWA... BUT SINCE THE CLDS ARE NOWHERE NEAR DEEP ENOUGH TO GET ICE CRYSTAL FORMATION... ONLY SPRINKLES ARE EXPECTED. THESE ARE NOT BEING PICKED UP BY ASOS AND WOULD NOT BE EXPECTED TO. SO WITH THE VORT PASSING THROUGH BY EARLY AFTERNOON WILL UPDATE FORECAST TO SCATTERED SPRINKLES ENDING FOLLOWED BY PARTIAL CLEARING. HIGHS MID 40S NRN CWA AND 45 TO 50 SRN CWA (BASED ON RUC SOUNDINGS ALLOWING SOME SUN BY MID TO LATE AFTERNOON. .GRR...NONE. WDM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 230 PM CST WED MAR 29 2000 PRIMARY QUESTION FOR THIS PACKAGE IS POSSIBILITY OF PRECIP OVER SWRN CWFA IN FIRST PD. A LARGE UPPER LOW SITS OVER THE NORTHEASTERN U.S. WHILE A DEEP TOUGH REMAINS SITUATED OVER THE WESTERN STATES. SPLIT FLOW CONTINUES TO DOMINATE THE MIDDLE PART OF THE COUNTRY...WITH A SHARP RIDGE SITTING OVER THE UPPER MIDWEST AND ZONAL FLOW ACROSS THE SOUTH. MORNING UPPER AIR ANALYSIS...AFTERNOON SATELLITE IMAGERY...AND CURRENT MODEL GRAPHICS ALL SHOW A BROAD TROF DANGLING ACROSS THE HIGH PLAINS THROUGH CENTRAL KS INTO NORTHERN OK. 21Z RUC AND SATELLITE PICS SHOW AN ALMOST CLOSED CIRCULATION OVER NORTH CENTRAL KS. MODEL PROGS SHOW THIS REGION OF CLOUDS AND PRECIP GETTING SOMEWHAT LOST IN THE OVERALL FLOW AS TIME PROGRESSES AND NOT AFFECTING OUR CWFA. 1000-500 RH FIELDS FIT WELL WITH THE MID LEVEL CLOUD DECK THAT HAS BEEN SITTING OVER SW MO ALL DAY. PROGS SHOW THIS DECK ADVANCING NORTHEAST THROUGH THE NIGHT BUT RETREATING EARLY THURSDAY AND NEVER COVERING THE ENTIRE CWFA. WL KEEP NRN AND ERN ZONES MOSTLY CLEAR...AND CONTINUE CURRENT CHANCE POPS FOR WRN AND SRN ZONES. FWC POP OF 7 OVERNIGHT CONTRASTS WITH FAN OF 51 IN COU INDICATING TIGHT PRECIP GRADIENT. BOTH FAN AND FWC POPS ARE DRY AS A BONE AFTER 1ST PD. FWC AND FAN TEMPS LOOK OKAY TNGT AND THURS. CLDS WL PREVENT REPEAT OF LAST NIGHTS LOWS. EVEN WITH CLEARING SKY THURS...DO NOT EXPECT SIGNIFICANT WARMING WITH WEAK NERLY FLOW SO WL KEEP MOST HIGHS AROUND 60. IN THE EXTENDED...BY SUNDAY THE MRF AND ECMWF BEGIN TO LIFT THE CLOSED LOW AND MERGE IT AS A SHORTWAVE INTO THE LARGER LONGWAVE TROF. THE CORRESPONDING SURFACE SYSTEM MOVES THROUGH THE MIDWEST SUNDAY AND MONDAY...SHOWING UP IN THE FMR GUIDANCE AS INCREASED CLOUDINESS AND HIGHER POPS. WILL ADD CHANCE WORDING TO ALL ZONES FOR THOSE TWO DAYS. .STL...NONE LENNING mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 952 AM EST WED MAR 29 2000 88D LOOPS INDICATING WAA SHOWERS ASSOCIATED WITH 850 MB WARM FRONT MOVING EAST INTO SE TENN/NC GA ATTM. PCPN IS FUTHER EAST THAN ANY OF THE 00Z MDLS &/OR LATEST RUC/06Z ETA INDICATED. PROBABLY WILL HAVE TO ADD POPS FOR AT LEAST NE GA MTNS & ADJACENT SW NC MTNS TO COVER THIS. OTHERWISE...AFTERNOON TRENDS OK. .GSP...NONE. CSH sc AREA FORECAST DISCUSSION FOR CENTRAL/NORTHCENTRAL AND NORTHEAST SOUTH DAKOTA AND WEST CENTRAL MINNESOTA NATIONAL WEATHER SERVICE ABERDEEN SD 1030 AM CST WED MAR 29 2000 12Z UPPER AIR ANALYSIS HAS VERTICALLY STACKED TROUGHS 850 THROUGH 500MB. THIS INDICATES THAT THE SURFACE TROUGH WILL MOVE TO THE EAST ONLY SLOWLY AND RUC AGREES. WILL TAKE OUT MENTION OF SHOWERS FOR THE PIERRE AND MOBRIDGE AREAS SINCE THE RETURNS FROM THE 88D ARE DIMINISHING AND HIGHER RH IS STAYING FURTHER WEST. SATELLITE SHOWS THE CLOUDS ABOUT AS FAR AS THE JAMES VALLEY AT 15Z AND RUC HAS THE 500MB RH STREAMING INTO ALL BUT THE FAR NORTHEAST. ADDED A FEW MORE CLOUDS TO THE FORECAST THOUGH TEMPERATURES SHOULD CONTINUE TO CLIMB. WINDS NEAR THE SURFACE TROUGH WILL BE A LITTLE STRONGER SO INCREASED WINDS SOME ALONG THE RIVER. .ABR...NONE JCB/DLH sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 130 PM CST WED MAR 29 2000 SCATTERED SHOWERS MOVED THROUGH MIDDLE TENNESSEE AND ARE EXITING THE AREA ATTM. BKN-OVC MID CLOUDS OVER THE AREA. INITIALLY...SOME LIGHT SLEET FELL AT OHX EVEN THOUGH THE TEMPERATURE WAS 46. EVAPORATIVE COOLING WILL CONTINUE UNTIL LOWER ATMOSPHERE BECOMES MORE MOIST. SFC LOW NEAR DFW IS QUASI-STATIONARY...BUT MODELS ALL MOVE IT SOUTH OF TENNESSEE TONIGHT. FORECAST PROBLEM...HOW MUCH RAIN TONIGHT AND TOMORROW... AVN MOVES THE LOW FASTER AND FARTHER NORTH THAN THE ETA OR NGM. AVN ALSO HAS MORE PRECIPITATION THAN NGM/ETA. I PREFER THE AVN SOLUTION BECAUSE AVN MOISTURE PATTERN AT 18Z WAS CLOSEST TO THE RUC AND IR SATELLITE. LIGHTNING STRIKES AT 17Z FOLLOWED THE AVN CURVE OF MOISTURE INTO OK WHILE NGM/ETA MOISTURE REMAINED FARTHER SOUTH. THE LIGHTNING STRIKE PATTERN ALONG THE AR-MO BORDER IS IN THE SAME POSITION AS THE AVN H8 EQUIVALENT POTENTIAL TEMPERATURE CONVERGENCE. THIS AREA WEAKENS AS IT MOVES OVER TN BUT IT IS THERE..SO WILL LEAVE MENTION OF THUNDERSTORMS ALL AREAS. ALL 3 MODELS KEPT THE STRONGEST MOISTURE AND DYNAMIC LIFT IN MS AND AL...BUT AVN BRINGS MORE INTO TN AND KEEPS IT HERE A LITTLE LONGER. ALL MODELS BEGIN TO CLEAR OUT MIDDLE TN THURSDAY AFTERNOON/EVENING WITH FAIR WEATHER FRIDAY AND SATURDAY. TEMPS ON AVN/FMR STILL SHOW WARM BIAS WITH CURRENT TEMPERATURES OVER 10 DEGREES BELOW FORECAST FROM FMR AND PREVIOUS FAN RUN. EVEN 12Z FWC TEMPERATURES ARE 7 DEGREES LOW AT 18Z...SO WILL DROP LOW TEMPERATURES TONIGHT TO 40-45 MOST AREAS. TEMPERATURES HAVE BEEN CONSISTENTLY TOO WARM ON FMR SO WILL UNDERCUT THEM ON THE EXTENDED. .BNA...NONE. BNA 41/64/40/68 72-0 CSV 39/60/36/65 7410 COONFIELD 16 tn SOUTHEAST TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 903 PM CST TUE MAR 28 2000 ISOLATED CELLS IN POLK COUNTY HAVE DISSIPATED...FRONT HAS CONTINUED THE SOUTHWARD MARCH. SEVERE THREAT HAS DIMINISHED BASED ON CURRENT RADAR TRENDS/SATELLITE/RUC GUIDANCE. BASED ON GRK/FWS RADARS THE FRONT IS CLIPPING ALONG AT 25 KNOTS AND SHOULD REACH A CXO/BRENHAM/GONZALES LINE AROUND 1045-1100 PM. MAY STILL GET AN ISOLATED SHRA/TSRA IN THE EASTERN ZONES. RADIATIONAL COOLING AT A PREMIUM AND WOULD NOT BE SURPRISED TO SEE PATCHY FOG BRIEFLY AFTER MIDNIGHT IN THE SOUTHERN ZONES BEFORE BEING SCOURED OUT. WILL NEED TO BUMP UP MINS ON GLS ISLAND A DEGREE OR TWO...AND WILL DROP MENTION OF SEVERE. WILL LIKELY BUMP COASTAL WINDS UP FOR THURSDAY...AND SLOW FROPA TO TOWARD MORNING FOR THE NEARSHORE. .KHGX...NONE. 45/43/D PRELIMS... NE UB 056/074 053/075 055 200 CLL UB 055/076 055/076 055 -00 IAH UB 059/078 058/078 060 000 GLS UB 066/074 064/074 067 000 tx SOUTHEAST TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 940 AM CST WED MAR 29 2000 VIS/IR IMAGERY AND KHGX SHOW SCATTERED SHOWERS AND THUNDERSTORMS IN THE NERN 1/4 OF THE CWA...AND RAPID CLEARING GENERALLY WEST OF I-35. THE MAIN FORECAST ISSUE IS TIMING AND HOW THAT AFFECTS SEVERE CONVECTION. THE 12Z CRP/BRO SOUNDINGS ARE STRONGLY CAPPED AND DEVOID OF SIGNIFICANT MOIST AIR ABOVE THE BOUNDARY LAYER...HENCE LITTLE OR NO CHANCE FOR CONVECTION. THE LCH/SHV/FWD SOUNDINGS HAVE WEAK CAPS...PLENTY OF MOIST AIR...AND LONG LINEAR HODOGRAPHS...HENCE GOOD CHANCES FOR SEVERE CONVECTION...PRIMARILY HAIL/WIND...TORNADOES NEAR LOCAL BOUNDARY ENHANCEMENT. THAT LEAVES HGX IN THE MIDDLE AS USUAL. THE MAIN LOW LEVEL FORCING WILL BE THE DRYLINE NOW IN WCNTRL TX. THE DRYLINE HAS MADE SOME PROGRESS IN SWRN TX AS EVIDENCED BY THE BIG DROP IN DEW POINT AT DRT THE PAST TWO HOURS. THE LATEST RUC RUNS INDICATE THE DRYLINE WILL REACH THE WRN BOUNDARY OF THE CWA AT 21Z. IN ADDITION...THE RUC INDICATES THE CAP WILL BE FULLY ERODED BY 18Z. AGREE WITH SPC AND GOING FORECAST FOCUSING ON THE NRN 1/2 OF THE CWA. OVERALL...THE FORECAST IS IN GOOD SHAPE. HOWEVER...AN UPDATE IS NECESSARY TO ALTER EARLY MORNING POPS WORDING...AND REFOCUS ATTENTION ON THIS AFTERNOON'S CONVECTION AND NEAR RECORD TEMPS. .KHGX...NONE. 31/47 UPDATED PRELIMS... CLL BB 087/055 081/057 076 400 IAH BB 088/057 083/058 078 300 GLS BB 081/064 077/064 075 200 INCREASED TODAY'S HIGH 3F tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1008 AM CST THU MAR 30 2000 CLOUDS LIKELY TO BE TROUBLESOME TODAY AS SOME AREAS ARE CLEARING OUT THIS MORNING WHILE CLOUDS ARE REDEVELOPING IN OTHERS. CURRENT TRENDS SUGGEST THAT CENTRAL AND SE ZONES WILL BE LEAST LIKELY TO SEE ANY SIGNIFICANT SUN, WHILE W AND N WILL SEE VARYING SKY CONDITIONS. WILL UPDATE TO INSERT VARIABLE CLOUDINESS W AND N, AND KEEP CENTRAL/SE MOSTLY CLOUDY FOR MOST OF THE AFTERNOON. CLOUDS OBVIOUSLY WILL HAVE SIGNIFICANT EFFECT ON AFTERNOON HIGH TEMPS IF THEY HOLD, BUT ONLY SHORT BREAKS WILL ALLOW SOME AREAS TO WARM TO CURRENT FORECAST HIGHS. WILL LOWER HIGHS SLIGHTLY IN CENTRAL/SE DUE TO MORE EXTENSIVE CLOUD COVER, BUT LEAVE TEMPS AS IS IN OTHER AREAS. WINDS WILL BE ADJUSTED TO DELAY ANY VEERING TO S OR SE, PER LATEST RUC/ETA. WE LIKELY WILL UPDATE AGAIN LATER TODAY IF AND WHEN CLOUD TRENDS BECOME MORE CLEAR. 24 .OUN... OK...NONE. TX...NONE. ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 951 AM EST THU MAR 30 2000 WATER VAPOR SHOWS WEAK SHORT WAVE MOVING ACROSS NORTH GA. DEEP MOISTURE ACROSS CENTRAL AND SOUTH GA. CURRENT RADAR SHOWS NUMEROUS SHOWERS ACROSS EAST CENTRAL GA MOVING EAST. SFC WARM FRONT ACROSS INLAND SOUTH COAST. BEST 850 MB WAA ACROSS EAST GA...SHIFTS EAST DURING AFTERNOON. CONVECTIVE PARAMETERS INDICATES AIRMASS MARGINALLY UNSTABLE THIS AFTERNOON WITH LIS AROUND -2. A FEW EMBEDDED TSTMS EXPECTED NEAR WARM FRONT. LOW LEVELS DRIER TO THE NORTH OF CAE...DEWPOINTS IN THE MID TO UPPER 40S NEAR CLT. RUCII SUGGEST BULK OF PRECIP WILL STAY MAINLY SOUTH OF CAE...EXPECT WARM FRONT WILL NOT MOVE MUCH FURTHER NORTH AS SFC LOW REMAINS WELL SOUTH OF REGION. SO...WILL LOWER POPS FROM CAE TO LANCASTER. CATEGORICAL AGS AREA. WILL LOWER TEMPS TO MID 60S AGS AREA. .CAE...NONE. AWP sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MEMPHIS TN 1003 AM CST THU MAR 30 2000 SURFACE ANALYSIS AT MID-MORNING SHOWS LOW PRESSURE CENTERED OVER SOUTH AL. COOL NORTHEAST WIND FLOW IS OCCURRING ACROSS OUR CWFA. SATELLITE SHOWS WIDESPREAD LOW CLOUDS FROM THE MIDSOUTH EASTWARD TO OK. SOME BREAKS NOTED IN THE CLOUDS. KNQA 88D STILL INDICATING SPOTTING LIGHT RAIN FROM WEST TN INTO NORTHEAST AR. WILL NEED TO UPDATE ZONES THIS MORNING. LATEST RUC SHOWS WEAK VORT MAX MOVING ACROSS WEST TN THIS AFTERNOON. THEREFORE WILL PROBABLY KEEP IN SMALL CHANCE OF RAIN FOR MOST OF WEST TN THIS AFTERNOON. LOOKING AT 12Z ETA CLOUD MACROS...WILL WORD ALL AREAS AS MOSTLY CLOUDY THIS AFTERNOON. COULD BE SOME CLEARING ACROSS THE EXTREME NORTH...BUT THIS WILL BE LATE AFTERNOON. ALSO...WILL NEED TO LOWER HIGH TEMPERATURE FORECAST MOST AREAS FOR THIS AFTERNOON. .MEM...NONE. tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 949 AM CST THU MAR 30 2000 CLOUDY/MOSTLY CLOUDY SKIES COVERED ALL OF THE MID STATE AT MID MORNING. THERE WAS HOWEVER SOME DISSIPATION OF THE LOWER CLOUDS ...ESPECIALLY ACROSS NORTHERN MIDDLE AT THIS TIME. THE ANALYSES THIS MORNING SHOWED A WEAK UPPER LEVEL SHORTWAVE TO OUR W CAUSING SOME LIGHT SHOWERS OR SPRINKLES OVER W TN...BUT THEY WERE GRADUALLY WEAKENING/DISSIPATING AS THEY MOVED E. SURFACE LOW PRESSURE WAS LOCATED OVER SW AL PER 14Z SURFACE ANALYSIS WITH INVERTED TROUGH FROM THE LOW N INTO NE MS...WITH THE SYSTEM CONTINUING TO MOVE E TODAY. LATEST RUC/ETA SHOWS CLOUDS SHOULD REMAIN ALL DAY AS THE WEAK UPPER LEVEL SHORTWAVE WEAKENS AS IT MOVES GENERALLY E ACROSS THE FORECAST AREA THIS AFTERNOON. TEMP AT OUR OFFICE ALREADY 54 DEGREES WITH FORECAST OF 50 TO 55 TODAY. WILL UPDATE AT LEAST SOME OF THE ZONES TO INCREASE HIGH TEMPS FOR THIS AFTERNOON. MAY MENTION SPRINKLES POSSIBLE FOR PART OF AREA BUT WILL TAKE ANOTHER LOOK AT THIS BEFORE ZONE ISSUANCE. .BNA...NONE. STEIGERWALDT tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 225 PM EST THU MAR 30 2000 WILL KEEP THIS DISCUSSION BRIEF DUE TO TORNADO WATCH #197. MESOLOW OVER FAR SW GA CURRENTLY MOVING E...WITH PRE-FRONTAL TROUGH EXTENDING SW THROUGH AQQ. STORM IN FAVORABLE POSITION E OF MESOLOW CURRENTLY MOVING E. WATER VAPOR IMAGES CURRENTLY SHOW AN UPPER JET STREAK CROSSING OUR CWA AND ESCORTING THIS WAVE OF PCPN EWD. HEAVY RAIN CONTINUES TO BE A CONCERN OVER OUR NE ZONES WHERE NEARLY STNRY FRONT EXISTS WITH STRONG N-S THERMAL GRADIENT. COLD FRONT STILL EXTENDS SW FROM MESOLOW NEAR MOB. 16Z RUC ADVERTISES THIS FEATURE TO REACH OUR ERN ZONES AROUND OR SHORTLY AFTER 03Z. CURRENT ZONES DO A CONSISTENT JOB WITH ENDING PCPN FROM W-E TNGT FOR MOST AREAS. BELIEVE ANOTHER ROUND OF PCPN WILL BE POSSIBLE EARLY TNGT WHEN COLD FRONT SW OF MOB PASSES E THROUGH OUR ZONES. WILL KEEP LEFTOVER POPS TNGT FOR ALL ZONES WITH PERHAPS RESIDUAL POPS THE FIRST PART OF FRI FOR EXTREME ERN ZONES. FWC HAS BEEN DOING A VERY POOR JOB WITH BOTH MAXIMUM TEMPERATURES AND POPS LATELY...SO WILL GO NEAR OR SLIGHTLY BELOW PERSISTENCE WITH CURRENT ZONE PACKAGE ON TEMPERATURES. FIRE WEATHER - WET GROUND IN THE AREA AND HIGH DEWPOINTS UPSTREAM SHOULD PRECLUDE A THREAT FOR LOW RH VALUES THROUGH FRIDAY. MARINE - WILL KEEP WINDS DOWN TO SCEC LEVELS AS BROAD SURFACE LOW TRACKS E JUST N OF WATERS. EXTENDED - LOOKS UNSETTLED...BUT WILL NOT MAKE SIGNIFICANT CHANGES NOW IN THE INTEREST OF TIME. FEEDBACK IS WELCOME. PRELIMINARY NUMBERS... TLH EB 063/077 053/079 4200 PFN EB 068/076 056/077 3000 DHN EB 063/077 053/079 3000 ABY EB 059/075 053/077 5300 VLD EB 064/079 057/080 4200 .TLH... AL...NONE GA...NONE. FL...NONE. TJT fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PEACHTREE CITY GA 315 PM EST THU MAR 30 2000 THE LOW NOW OVER WESTERN FLORIDA PANHANDLE SHOULD MOVE ACROSS SOUTH GEORGIA/NORTH FLORIDA TONIGHT AND OFF THE COAST BY EARLY FRIDAY MORNING. HIGH PRESSURE BUILDS IN TOWARD MID ATLANTIC COAST...BUT QUITE A BIT OF LOW LEVEL MOISTURE REMAINS OVER THE AREA THROUGH FRIDAY. APPEARS BULK OF THE PRECIP SOUTHEAST OF OUR CWFA BUT SHORT WAVE DEPICTED BY RUC TO MOVE JUST NORTH OF OUR AREA THIS EVENING. WILL CARRY SMALL POP FOR NORTHEAST GA THIS EVENING DUE TO THIS FEATURE. FURTHER SOUTH WILL CARRY SMALL POP CLOSER TO THE FRONT. THEN DRY THROUGH SATURDAY. AVIATION SHOWS INCREASING HIGH CLOUDS SATURDAY AHEAD OF THE NEXT SYSTEM WITH CHANCE OF RAIN AGAIN SATURDAY NIGHT. CONCERNING TEMPERATURES...FWC/FAN NUMBERS ARE CLOSE ALL PERIODS AND WILL STICK CLOSE TO THEM. UPPER LEVEL RIDGE OVER THE STATE SATURDAY SO WARM TEMPERATURES LOOK OKAY. ATL 51/71 49/75 1000 AHN 48/72 47/76 2000 RMG 46/70 43/74 1000 CSG 53/74 51/78 2000 MCN 52/74 49/78 2000 .ATL...NONE. 26 ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 230 PM CST THU MAR 30 2000 18Z SURFACE CHART SHOWS HIGH PRESSURE RIDGING ACROSS THE GREAT LAKES. WATER VAPOR AND RUC MODEL SHOW VORT MAX SLIDING ACROSS SOUTHERN MISSOURI. SOME PRECIP WITH THE VORT MAX...SHOULD STAY SOUTH OF OUR CWA. AM EXPECTING SOME HIGH-LEVEL CLOUDINESS MUCH OF THE NIGHT. THIS...AND NUMERICAL GUIDANCE...MATCH WELL WITH GOING FORECAST AND WILL LEAVE THAT PART ALONE. MAIN PROBLEMS TODAY FOCUS ON SATURDAY AND EARLY NEXT WEEK. LOW PRESSURE...AND ASSOCIATED FRONT...WAS FORMING IN THE DAKOTAS TODAY. MODELS MOSTLY AGREEABLE THAT THIS WILL MOVE EAST THE NEXT COUPLE OF DAYS...AS THE HIGH PRESSURE RIDGE SLIDES UNDERNEATH THE LOW. BEST PRECIP CHANCES SHOULD MAINLY BE NORTH OF ILLINOIS...BUT PRESENCE OF SOME LIFT ON SATURDAY WARRANTS A LOW POP FOR THE NORTHERN CWA...AS IS IN THE CURRENT FORECAST. WILL GO CLOSER TO THE WARMER FAN NUMBERS FOR SATURDAY. GOING INTO THE EXTENDED...MRF HAS CHANGED SOME FROM YESTERDAYS RUN. CUT-OFF UPPER LOW IN THE SOUTHWEST U.S. WILL NOW MOVE EAST ALONG THE SOUTHERN STATES...RATHER THAN KICKING NORTHEAST. SECOND PIECE OF ENERGY TO MOVE ALONG THE U.S./CANADIAN BORDER...WITH MAIN SURFACE LOW STAYING WELL NORTH IN CANADA. WITH HIGH PRESSURE IN THE SOUTHEAST U.S. AFFECTING OUR AREA...WILL TAKE PRECIP OUT OF SUNDAYS FORECAST. NCEP AND MRF ARE SLOWER WITH NEXT SYSTEM...KEEPING IT NORTHWEST OF ILLINOIS AT 12Z MONDAY...WHILE EUROPEAN AND NOGAPS MODELS SHOW IT THROUGH MOST OF THE STATE. WILL GO THE SLOWER ROUTE...KEEPING SHOWERS/THUNDERSTORMS IN MONDAYS FORECAST...WITH RAIN AND COOLER WEATHER FOR TUESDAY. COORDINATED WITH DVN. ...PRELIMINARY CCF FOR COORDINATION ONLY... SPI AE 037/066 043/064 045 72000 PIA AE 036/066 041/062 043 72000 DEC AE 035/066 042/064 045 72000 CMI UE 033/064 041/064 045 72000 MTO UE 035/066 041/064 044 72000 LWV UB 035/066 041/067 047 72000 .ILX... IL...NONE. GEELHART/PLAHMER il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MEMPHIS TN 247 PM CST THU MAR 30 2000 SURFACE LOW PRESSURE LOCATED OVER SOUTHEASTERN AL THIS AFTERNOON AS IT CONTINUES TO MOVE EASTWARD. KNQA 88D SHOWING A FEW LINGERING ECHOES...LIGHT RAIN...OVER NORTHWEST TN. WEAK VORT MAX HELPING TO CAUSE THIS LIGHT RAIN. LOW CLOUDS CONTINUE FROM TN TO OK WITH SOME BREAKS SHOWN BY SATELLITE AND SOME CLEARING NOTED FROM THE NORTH. SHORT RANGE MODELS IN CLOSE AGREEMENT THROUGH 12Z SATURDAY. FOR TONIGHT...ANY LINGERING LIGHT RAIN EXPECTED TO BE OUT OF THE CWFA BY 00Z AS LATEST RUC SHOWS VORT MAX WELL TO THE EAST. BASED ON MODEL CLOUD MACROS...CLOUDS FORECAST TO CONTINUE CLEARING FROM THE NORTH TONIGHT. WILL GO JUST SLIGHTLY BELOW FWC GUIDANCE FOR LOWS TONIGHT WITH TEMPERATURES NOT WARMING ALL THAT MUCH TODAY. FOR FRIDAY...RIDGING ALOFT WILL SPREAD OVER THE MIDSOUTH. LOTS MORE SUN WILL OCCUR HELPING BOOST TEMPERATURES TO NEAR FAN/FWC NUMBERS. FRIDAY NIGHT...MID AND HIGH LEVEL CLOUDS WILL SPREAD INTO THE AREA FROM THE SOUTHWEST...BUT STILL DRY. WITH NORTHEAST LOW LEVEL WINDS CONTINUING TO FEED DRY AIR INTO THE AREA...THINK FWC TEMPERATURES MAY BE A LITTLE WARM. CONFIDENCE IN FORECAST SATURDAY AFTERNOON THROUGH SUNDAY IS LOW WITH MODEL DIFFERENCES. LATEST QPF GUIDANCE FROM HPC DOES NOT FORECAST ANY RAIN FOR OUR CWFA THROUGH SATURDAY...AND WILL GO ALONG WITH THIS THINKING. AVN MODEL SHOWS SHORT WAVE PASSING TO OUR SOUTH SATURDAY NIGHT. WILL MENTION CHANCE OF SHOWERS FOR SOUTHERN COUNTIES OF OUR CWFA ACROSS NORTH MS SATURDAY NIGHT. WILL INCLUDE CHANCE OF SHOWERS AND THUNDERSTORMS IN FORECAST FOR MONDAY AND TUESDAY WITH MOISTURE INCREASING AND APPROACH OF COLD FRONT FROM THE NORTHWEST. .MEM...NONE. tn