AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 825 PM EDT MON APR 30 2001 00 UTC SURFACE ANALYSIS SHOWS AND EAST-WEST ORIENTED SURFACE RIDGE JUST NORTH OF THE FORECAST AREA. THE ISOLATED SHOWERS ACROSS THE FORECAST AREA HAVE DISSIPATED, AND POPS WILL BE ELIMINATED ON THE NEXT UPDATE. OTHERWISE, NO MAJOR CHANGES ARE EXPECTED. WINDS/SEAS HAVE DIMINISHED SLIGHTLY, BUT THE LATEST RUC FORECASTS THEM TO INCREASE LATER TONIGHT LIKE THEY DID LAST NIGHT. .TLH... AL...NONE. GA...NONE. FL...SCA OFFSHORE WATERS BIG BEND AND PANHANDLE. FIRE WX WATCH ALL ZONES TUESDAY AFTERNOON DUE TO POSSIBLE HIGH DISPERSION INDICES AND RH DURATIONS. fl EAST CENTRAL FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 727 PM EDT MON APR 30 2001 CURRENTLY...BREEZY EAST WINDS CONTINUE ACROSS THE AREA...THOUGH SURFACE DEW POINTS HAVE BEEN RATHER LOW (LOWER 60S) FOR SUCH A PERSISTENT FLOW OFF OF MID 70 DEGREE WATERS. WATER VAPOR IMAGERY/RUC ANALYSIS SHOWING UPPER TROUGH AXIS AND ASSOCIATED DRYING ALOFT PASSING TO THE EAST OF THE AREA. NARROW BAND OF SCATTERED SHOWERS EXTENDED FROM CANAVERAL TO ORLANDO. OTHERWISE THERE WERE JUST A FEW SHOWERS AFFECTING THE AREA. OVERNIGHT...PASSAGE OF THE UPPER TROUGH AND LOSS OF LARGE SCALE LIFT SHOULD KEEP COASTAL POPS IN THE SCATTERED RANGE. GREATER COVERAGE WILL OCCUR IN A FEW ZONES WHERE CONVERGENCE LINES ARE MOST PERSISTENT...BUT DIFFICULT TO PICK EXACTLY WHICH ONES. TYPICALLY IN SUCH A BREEZY EAST FLOW REGIME...THERE WILL BE SOME LOCALLY HEAVY RAIN...WHICH HAS ALREADY OCCURRED IN A FEW SPOTS AND MOST RECENTLY AT THE SHUTTLE LANDING SITE. EAST FLOW IS STRONG ENOUGH TO PUSH COASTAL SHOWERS INLAND SO 20 PERCENT THERE LOOKS OKAY. MAY BUMP UP NORTH BREVARD GROUP TO 30 PERCENT...OTHERWISE DO NOT ANTICIPATE ANY CHANGES. MARINE...BAD BOATING CONDITIONS WITH BUOYS SHOWING WINDS 20 TO 25 KNOTS AND SEAS 8 TO 10 FEET. NO CHANGES. .MLB...SMALL CRAFT ADVISORY FLAGLER BEACH TO JUPITER INLET. PUBLIC/MARINE...LASCODY AVIATION/FIRE WX...WIMMER fl EAST CENTRAL FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 1010 AM EDT MON APR 30 2001 CURRENT...CWA REMAINS FIRMLY ENTRENCHED WITHIN CRCLN AROUND SOUTH SIDE OF STRONG HIGH PRES CENTERED ALONG THE ATLC SEABOARD. "REX" TYPE BLOCK AT H50 WITH RIDGE OVER TN VALLEY AND TROUGH IN THE NE GOMEX VERY SLOWLY DRIFTING EAST IN TANDEM ATTM. MULTIPLE WEAK MID LEVEL VORT CENTERS (NOTED ON RUC ANYLS) EMBEDDED WITHIN THE GOMEX TROUGH OVER THE NORTHERN GOMEX/GULF COAST WITH AN ELONGATED LOBE OF VORTICITY OVER THE GOMEX BETWEEN 80-90W AND 25-27N. CWA IS BETWEEN THE TWO ATTM. KMLB 88D SHOWS CONVECTIVE SHOWERS MOVING ASHORE NEAR PALM BAY...THEN EXTENDING T ABOUT 30-40NM OFFSHORE OF KMXR. AREA OF STRATIFORM PRECIP IS NOTED OVER THE SOUTHERN 3 COS. 12Z RAOBS SHOW HIGHEST PWATS CONTINUE OVER SOUTH FL (1.4" TO 1.6") WITH DRIER LOW-MID LEVEL AIR STILL HOLDING FAST OVER EAST CENTRAL/NE FL (0.8" TO 0.9"...A FEW TENTHS HIGHER AT KTBW. ANOTHER FORECAST WHERE GENERAL PATTERN IS PRETTY STRAIGHTFORWARD... YET THE MINUTIAE WILL MORE OF A DETERMINANT. ETA/NGM INDICATE TREND TOWARD INCREASING DIFF PVA OVER THE ENTIRE CWA. THE AVN...WHICH USUALLY HANDLES THE H50 VORT FIELDS A BIT BETTER...IS LESS BULLISH ON THIS...ESP OVER THE SOUTHERN CWA. ALL THREE SHORT RANGE MODELS AS WELL AS THE 06Z MESOETA SHOW AN INCREASE IN H25 DIVG THIS AFTERNOON ...AND THIS LINES UP WITH 6HR TIME LAPSE OF WATER VAPOR/RUC ANLYS. BASED ON WATER VAPOR WHICH SHOWS AS DISTINCT N-S LINE WHICH LINES UP WITH LEADING EDGE OF VORT MINIMA...WILL GO WITH THE AVN SOLUTION WHICH WOULD PLACE SOUTHERN COUNTIES IN NVA A GOOD PART OF THE AFTERNOON. FARTHER NORTH...PRECIP CHANCES 20-30 AT BEST LOOKS FINE OVERALL TREND OF THE ZFP IS ON THE MARK AS HIGHEST PRECIP CHANCES WILL BE SOUTH (IN PROXIMITY OF DEEPER MOISTURE) AND NEAR THE COAST AS WEAK CONVERGENCE BANDS CONTINUE TO MOVE ASHORE. QUANTITATIVELY... WE MAY NEED TO TWEAK VALUES DOWN ACROSS THE NORTH BY 10%. IF IT WEREN'T FOR WHAT I PERCEIVE AS A SLIGHTLY LESS CONDUCIVE SYNOPTIC PATTERN TEMPORARILY EVOLVING OVER THE SOUTHERN COUNTIES THIS AFTNN I WOULD CERTAINLY BUMP THEM UP TO 70-80% PER CURRENT RADAR COVERAGE. AS IT STANDS NOW...I THINK 50-60 WILL SUFFICE. MARINE...FORECAST LOOKS FINE. WILL TWEAK SEAS UP TO 8-10 TO COVER OCCASIONAL 9.5FT @41009 AND 10FT @41010. THANKS TBW...APPRECIATE YOUR INSIGHTS. .MLB...SCA FLAGLER BEACH TO JUPITER INLET. PUBLIC/MARINE...CRISTALDI AVIATION/FIRE WX...WIMMER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 1000 AM CDT MON APR 30 2001 MID AND HIGH LEVEL CLOUDINESS AHEAD OF SURFACE FRONT/TROF ACROSS SOUTHERN HIGH PLAINS ARE APPROACHING THE FORECAST AREA FROM THE WEST THIS MORNING. HOWEVER CLOUDS ARE DISSIPATING AS THEY MOVE INTO SURFACE RIDGE OVER THE EASTERN STATES. SKIES SHOULD BECOME PARTLY CLOUDY OVER NORTHERN SECTIONS BY AFTERNOON. LATEST RUC SHOWS INCREASING LOW LEVEL MOISTURE FROM THE EAST THIS AFTERNOON WITH INCREASING MOISTURE ABOVE 500 MB ACROSS THE NORTHWEST SECTION THIS AFTERNOON. WILL CHANGE WORDING ACROSS THE EAST TO BECOMING PARTLY CLOUDY WITH CU FORMING DURING THE AFTERNOON. AIRMASS IS SLIGHTLY UNSTABLE BUT DRIER THAN SUNDAY SO WILL NOT ADD ANY SHOWERS IN. NO OTHER CHANGES NEEDED FOR UPDATE. .SHV...NONE. 09 la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 936 PM EDT MON APR 30 2001 AREA OF SCT SHRA/TSRA HAS DEVELOPED OVER SRN LAKE MI EARLIER IN THE EVENING...AND HAS MADE IT'S WAY NE INTO CENTRAL LAKE MI AROUND AND JUST W OF MKG. MINOR CONVECTION SEEMS TO BE HOLDING TOGETHER DESPITE MOVING INTO MORE STABLE...DRIER AIR ASSOCIATED WITH THE SFC RIDGE. LATEST RUC AND MESOETA INDICATE GRADUALLY INCREASING SBCAPES ACROSS MUCH OF LAKE MICHIGAN AND FAR WRN LOWER MI WITH THE APPROACH OF THE 850 MB THETA E RIDGE...WHICH IS LIKELY WHY THIS WEAK CONVECTION IS HOLDING TOGETHER. WILL UPDATE ZONES TO GO WITH SCT SHRA/TSRA FOR THE REMAINDER OF THE NIGHT FOR ERN UPR AND MOST OF NRN LOWER MI. WILL INTRODUCE A SLIGHTLY CHANCE OF SHRA/TSRA TO THE SE PORTION OF THE CWA LATE TONIGHT AS IT DOES APPEAR THAT GREATER INSTABILITY AND LOW LEVEL MOISTURE WILL MAKE ITS WAY INTO THIS AREA LATE. WILL ALSO UPDATE WINDS AS MOST PLACES ARE NOW REPORTING SOUTH WINDS OF 10 TO 15 MPH. TEMP FORECAST WILL GO UNCHANGED. .APX...NONE. EME mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 430 PM EDT MON APR 30 2001 MAIN FCST CONCERNS THIS PACKAGE AGAIN INCLUDE PCPN CHANCES/TIMING ALONG WITH TSRA POTENTIAL TONIGHT AND TUES NIGHT. WV IMAGERY AND RUC ANALYSIS INDICATED RDG OVER ERN NOAM WITH MORE ZONAL FLOW FROM PAC NW TOWARD THE PLAINS. WRN GRT LAKES WAS IN SW FLOW AHEAD OF PROGRESSIVE TROUGH TO THE WEST DRIVEN BY 120 KT H3 JET INTO THE NRN PLAINS. ADDITIONAL JET ENERGY WAS MOVING ONSHORE INTO THE PAC NW. BAND OF SHRA FROM NE MN INTO WRN IA WAS SUPPORTED BY LLVL CONVERGENCE ALONG WEAK FRONT AND SOME H3 DIV WITH RIGHT ENTRANCE OF JET OVER WRN ONTARIO. DIMINISHING PRES RISES BEHIND THE FRONT SUGGEST CONTINUED SLOW EASTWARD PROGRESS. SO FAR...ONLY TSRA NOTED WERE OVER IA CLOSER TO BETTER INSTABILITY. EVEN WITH TEMPS INTO THE LO TO MID 80S F...DEWPOINTS WERE GENERALLY IN THE MID 40S LEADING TO CAPES AOB 500 J/KG. WHERE DEEPER MIXING HAS OCCURRED...TD HAVE FALLEN INTO THE 20SF (KSAW...KEGV). KMQT VAD WINDS SHOWED 30-35 KT 1-2K AGL WINDS. STRONG INSOLATION HAS DRIVEN ENOUGH MIXING FOR MUCH OF THAT TO BE TRANSFERRED TO THE SFC...WITH GUSTS TO NEAR 40 MPH OVER CNTRL UPR MI. TONIGHT...EXPECT PCPN TO CONTINUE GRADUAL SPREAD TO THE EAST INTO WRN UPR MI THIS EVENING (21Z-03Z) AND CNTRL/EAST OVERNIGHT (01Z-06Z)...PER RADAR TRENDS AND 18Z RUC. AS FRONT CONTINUES TO DISSIPATE...PCPN COVERAGE SHOULD BE ONLY SCT AT MOST BY THE TIME IT REACHES CNTRL UPR MI WITH QPF AMOUNTS DROPPING OFF SIGNIFICANTLY. GIVEN CURRENT TRENDS...WITH LACK OF CONVECTION AND NO UPSTREAM FEATURE TO SIGNIFICANTLY STRENGTHEN MOISTURE INFLOW OR UPWARD MOTION...WL DOWNPLAY THUNDER AND MENTION ONLY FOR SW. INCREASING CLOUDS LATE THIS AFTERNOON AND DIURNAL STABILIZATION SHOULD ALLOW THE WINDS TO DROP OFF QUICKLY THIS EVENING. TUESDAY...WL REMOVE PCPN AS ETA/AVN SUGGEST SUBSIDENCE OVER THE AREA WITH SHRTWV RDG AHEAD OF DEEPENING NRN PLAINS TROF. TEMPS SHOULD AGAIN CLIMB WELL ABV NORMAL WITH H8 TEMPS OF 12C-14C SUPPORTING READINGS TO NEAR 80 F. TUESDAY NIGHT...MUCH STRONGER FRONT MOVES THROUGH WITH BETTER CHANCE FOR SCT SHRA. WHILE ETA CAPE MAY AGAIN BE OVERDONE...VALUES APPROACHING 1000 J/KG ALONG WITH VIGOROUS MID LVL WIND FIELDS ENOUGH FOR SLGT SVR THREAT...PER SPC. WEDNESDAY...ETA AND AVN AGAIN DISPLAY LARGE DIFFERENCES WITH RESPECT TO WX FOR UPR MI. WL GO WITH MORE CONSISTENT AVN (BACKED UP BY UKMET/CANADIAN) H5 SCENARIO WITH SHRTWV FARTHER NORTH INTO WRN ONTARIO. ETA H5 SHRTWV POSITION LEAVES UPR MI IN DRY WEDGE WED...WHILE AVN SHOWS POTENTIAL FROM PCPN WITH WEAK SHRTWVS MOVING INTO THE WRN LAKES WITH ISENTROPIC LIFT AND OVERRUNNING OF WEAK FRONT TO THE SOUTH. AVN SHOWALTER AND SFC LI SUGGEST MAINLY SHRA WITH CONVECTION WELL TO THE SOUTH. EXTENDED...MRF/UKMET/ECMWF WERE IN REASONABLE AGREEMENT INTO THIS WEEKEND AS ECMWF HAS TRENDED TOWARD FASTER PROGRESSION OF FRONT TO THE SOUTH OF UPR MI BY FRI. SO...WL TAKE OUT MENTION OF PCPN FRI WITH BULK OF THE DAY PTSUNNY AS SFC HI PRES SETTLES IN. AREAS ALONG LK SUPERIOR...IN PARTICULAR WILL BE NOTICEABLY COOLER (CLOSER TO MEX GUIDANCE) WITH NRLY SFC FLOW. SFC HI WILL DOMINATE OVER THE WEEKEND WITH DRY WEATHER AND MOSTLY CLEAR SKIES. WL HOLD OFF ON ANY PCPN FOR MONDAY AS MRF MAY BE A BIT FAST WITH PROGRESSION OF WRN CONUS LO. PLENTY OF UNCERTAINTY BY DAY 7 THOUGH WITH WIDENING ENSEMBLE SPREAD AND MDL DIFFERENCES WITH NRN STREAM JET ENERGY OR KICKER TO AID PATTERN PROGRESSION. .MQT...NONE. JLB mi AREA FORECAST DISCUSSION...RETRANSMITTED NATIONAL WEATHER SERVICE MARQUETTE MI 1130 AM EDT MON APR 30 2001 WV LOOP AND 12Z RAOBS SHOW H5 TROUGH OVR NCTNRL CONUS WITH UPR RIDGING FOUND ON BOTH WEST AND EAST COASTS. PRIMARY SHRTWV OF CONCERN FOR TDY ATTM IS PUNCHING INTO SW MN. AT THE SFC...A FRONTAL BOUNDARY LIES FM NRN ONTARIO INTO CNTRL MN...EXTENDING SW INTO ERN KS. BOUNDARY SERVING AS A FOCUS TO POOL SFC DWPTS FM 50-55F WITH DWPTS IN THE 30S ON BOTH SIDES OF BOUNDARY. OVRNIGHT LLJ AIDED SHRA ALONG BOUNDARY ARE DISSIPPATING AS THEY MOVE NE INTO ONTARIO PER KDLH 88D. MAIN CONCERNS TODAY FOCUS ON AMOUNT OF MOISTURE ADVECTION INTO FA AHEAD OF INCOMING BOUNDARY...AND DEVELOPMENT/TIMING OF CONVECTION ALONG BOUNDARY. RAOBS FM INL/MPX/GRB POINT TO SHARP GRADIANT TO H85 DWPT ACROSS AREA WITH 9C FOUND AT INL BUT ONLY 3C AT GRB. 12Z ETA/LATEST RUC DEPICT THAT THIS RIBBON OF 6-8C TD WILL SLIDE TOWARD UPR MI AFT 18Z AS SFC/H85 FRONTAL BOUNDARY ADVANCES EAST ALSO. EXPECT INCOMING SFC/H85 TROUGH AND WEAK H7-H3 Q-VECTOR CONVERGENCE TO PRODUCE SCT -SHRA AFT 21Z...ESPECIALLY IN AREA OF BEST H95-H85 CONVERGENCE ALONG BOUNDARY. HAVE TAKEN ANY POPS OUT OF EAST AS BOUNDARY WON/T ARRIVE UNTIL EVENING HOURS. AS FOR POTENTIAL OF ANY THUNDER...SFC DEWPTS REMAIN IN THE 40S AHEAD OF BOUNDARY AND WITH LACK OF COUPLED DYNAMICS AND LOW-LEVEL FORCING DON/T EXPECT MUCH IN THE WAY OF SIG DWPT ADVECTION IN AREAS THAT SEE PLENTY OF SUNSHINE. IN FACT...MECHANICAL MIXING WILL ONLY LOWER DWPTS INTO LOWER 40S ACROSS FA THRU AFTN. MAXIMUM POTENTIAL FOR ANY THUNDER WILL EXIST OVR FAR SWRN FA WHERE DWPTS COULD CLIMB INTO 50-55F RANGE BEFORE FRONT APPROACHES. USING A SOUNDING WITH INITAIL SFC PARCEL OF 75/55 AT IWD AT 21Z YIELDS AROUND 700 J/KG OF CAPE WITH LI/S AROUND -3C. FARTHER EAST AT IMT...A PROFILE WITH SFC PARCEL OF 78/50 GIVES CAPE VALUES ONLY APPROACHING 400J/KG. SO ALTHOUGH SOME THUNDER IS A POSSIBILITY WITH APPROACHING FRONT AND CONVERGENCE/WEAKENING RRQ OF JET STREAK CROSSING ONTARIO...AND H85 WINDS NEARING 45KT BY EVENING...LACK OF SFC-H85 MOISTURE SHOULD LIMIT COVERAGE/INTENSITY. OTHERWISE...TEMPS GENERALLY LOOK ON TRACK FOR FA. IN IMMEDIATE SHORELINE LOCATIONS ALONG LK SUPERIOR IN MQT COUNTY COULD BE A SLIGHT LAKE BREEZE DEVELOP AS LAND/LAKE DLT T/S ARE ALREADY APPROACHING 20C...HELPING TO OFFSET BLYR/H95 WINDS AROUND 20KT. 15Z OB FM PRESQUE ILSE SHOWING CALM WIND...USUALLY A SIGN OF ERLY LK BREEZE COMPONENT TRYING TO ASSERT ITSELF. WILL NOT MENTION ANY COOLER NEAR LAKE WORDING IN ZONES AS AFFECT SHOULD BE CONFINED TO LESS THAN A MILE OR SO INLAND...WITH SW GRAD FLOW OVERCOMING LK BREEZE IN MOST OTHER LOCALES. ONLY PRIMARY CHANGES BESIDES DELAYING TIMING OF PRECIP OVR ERN ZONES WAS TO FRESHEN WIND WORDING AS MIXING (WHICH SHOULD PRODUCE SFC WINDS GUSTING TO NEAR 30 MPH) IS NOW ONGOING AND SHOULD CONTINUE FOR REMAINDER OF AFTN. .MQT...NONE. JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTH PLATTE NE 220 PM CDT MON APR 30 2001 ...FORECAST CHALLENGE WILL BE POPS THIS EVENING THEN TEMPS TUESDAY... FEW CLOUDS ACROSS THE NORTH WITH CIRRUS SHIELD TO THE WEST AT 18Z AND NO REFLECTIVITY RETURNS ON THE KLNX 88D. THE HAND SURFACE ANALYSIS SHOWED A TROUGH EXTENDING WEST ACROSS THE SANDHILLS FROM LOW CENTER NEAR OFK. SEMI STATIONARY FRONT EXTENDED SOUTHWEST FROM NEAR DLH...TO ORC...OFK...HSI...LNX...DDC AND TO THE TEXAS PANHANDLE SOUTH OF DHT. WATER VAPOR IMAGERY LOOPS SHOWS DRYING IN THE NORTHWEST IN AREA OF INCREASING SUBSIDENCE. MODELS SHOW VARIATIONS IN POSITION OF SURFACE BOUNDARIES OVER THE PLAINS THROUGH THE FIRST 24 HOURS THEN REMAIN SIMILAR THROUGH 60 HOURS BEYOND PRECIPITAL AMOUNTS. MESOETA AND RUC USED THROUGH FIRST 24 HOURS THEN BLEND OF ETA/AVN BEYOND. STEEP LAPSE RATES IN THE WEST WILL DECREASE FOR THE REST OF THE AFTERNOON AS SUBSIDENCE INCREASE ACROSS THE WEST. COOLER AIR FILTERING IN FROM THE NORTHWEST WILL KEEP BEST CHANCE OF SHOWERS TO BE IN THE EXTREME EASTERN PORTIONS OF THE FORECAST AREA FROM 5 TO 8 PM THIS EVENING. LAPSE RATES IN 700-500 MB LAYER INCREASE TO 7.25 C/KM WITH INCREASED DIVERGENCE AS H5 SHORTWAVE MOVES EAST. LOW LEVEL CONVERGENCE INCREASES OVER HOLT AND BOYD COUNTIES WITH SURFACE LOW OVER EASTERN NEBRASKA. BY 01/00Z THE H5 WAVE MOVES EAST AND SUBSIDENCE INCREASES ACROSS THE NORTH CENTRAL WITH CHANCE FOR SHOWERS ENDING. SURFACE WINDS TURN TO THE SOUTHWEST BY MIDNIGHT AS AREA OF LOW PRESSURE DEVELOPS IN RESPONSE TO NEAR ZONAL FLOW ALOFT ACROSS THE NORTHERN PLAINS AND H3 JET INCREASING DIVERGENCE ALOFT. TEMPERATURES OVERNIGHT WILL MAINLY BE IN THE 40S WITH GUIDANCE CLOSE. TUESDAY TEMPERATURES WILL BE THE MAIN CONCERN AS A COLD FRONT DESCENDS SOUTH INTO THE NORTHWEST DURING THE MORNING...PUSHING SOUTHEAST THROUGH ONL...BBW AND IML BY 1 PM CDT. FEW CLOUDS WILL ACCOMPANY THE INITIAL FRONTAL PASSAGE WITH THE MAIN ENERGY REMAINING ACROSS THE NORTHERN PLAINS. HOWEVER AFTERNOON HEATING WILL RESULT IN STEEPENING LAPSE RATES TO OVER 8 C/KM AS FRONT MOVES TO ALONG THE KANSAS/NEBRASKA STATELINE BY 02/00Z IN THE SOUTHWEST. MOISTURE WILL BE LIMITED WITH ANY CONVECTION HOLDING OFF TILL EVENING AND FOCUS ACROSS THE SOUTHWEST. THEN AS CONVERGENCE INCREASES ALONG AND NORTH OF THE FRONTAL BOUNDARY CLOUDS INCREASING OVERNIGHT AND THE BEST CHANCE FOR PRECIP ACROSS THE SOUTH. THE FRONT CONTINUES TO PUSH SOUTHEAST THROUGH CENTRAL KANSAS TUESDAY NIGHT WITH A SURFACE RIDGE AXIS TO EXTEND EAST ACROSS THE FORECAST AREA. THE H3 JET REMAINS EAST WEST ACROSS THE AREA INTO WEDNESDAY WITH THE SEMI STATIONARY FRONT TO BACK WEST TO THE LEE OF THE ROCKIES WHERE UPSLOPE FLOW WILL GENERATE WIDESPREAD CLOUD COVERAGE AND CHANCE OF SHOWERS INTO THE SOUTHERN PANHANDLE. THE BROAD H5 FLOW WILL HAVE EMBEDDED WAVES WITH THE POTENTIAL FOR STORMS TO MOVE IN FROM THE SOUTHWEST DURING THE OVERNIGHT HOURS WITH INCREASED DIVERGENCE ALOFT. GUIDANCE CLOSE AND FOLLOWED. EXTENSIVE CLOUD COVERAGE COVERS THE SOUTH INTO WEDNESDAY AND WILL LIMIT TEMPERATURES WHILE THE NORTH SEES SOME SUNSHINE WEDNESDAY AND WARMER READINGS IN THE 60S. WEAK HIGH PRESSURE WILL RIDGE NORTHEAST DURING THE DAY WITH PARTLY SUNNY SKIES. MODELS HAVE BACKED OFF WITH COOLER GUIDANCES WITH BLEND USED. IN THE EXTENDED H25 JET REORIENTATES THEN TAKES A DIVES SOUTHEAST ALONG THE WEST COAST AND CARVES AN H5 TROUGH OUT ON THURSDAY. THE H5 LOW CLOSES OFF AND BECOMES DISPLACED FROM THE MEAN FLOW FOR THE REST OF THE PERIOD GRADUALLY LIFTING NORTHEAST THROUGH SUNDAY NIGHT. THE CLOSED SYSTEM OPENS MONDAY WHILE MOVING EAST ACROSS THE PLAINS. THURSDAY A SURFACE FRONT WILL BE TO THE SOUTHEAST AND BEGIN TO STALL AS HIGH PRESSURE BUILDS IN FROM THE NORTH. THE CONVERGENCE BETWEEN THESE TWO SURFACE FEATURES WILL RESULT IN INCREASED CLOUDS AND A CHANCE OF SHOWERS AND THUNDERSTORMS FRIDAY AND SATURDAY... A SERIES OF H5 WAVES WILL ROTATE NORTH ACROSS THE FORECAST AREA AS THE H5 LOW LIFTS NORTH ACROSS THE ROCKIES. THEN SUNDAY THE SURFACE HIGH BUILDS SOUTHEAST INTO THE OHIO VALLEY WITH A SURFACE LOW TO FORM ALONG AN INVERTED TROUGH IN THE SOUTHWEST AND MOVE NORTHEAST THROUGH MONDAY MORNING. KEEPING A CHANCE FOR RAIN OR SHOWERS INTO MONDAY BEFORE THE SYSTEM EXITS EAST. THE EXTENSIVE CLOUD COVERAGE AND RAINFALL WILL LIMIT HEATING BUT WILL STICK WITH GUIDANCES AS LITTLE RANGE MAY OCCUR EACH DAY. .LBF...NONE TLK ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 955 AM EDT MON APR 30 2001 CLOUDS EAST OF MTNS WILL BE WITH US FOR MUCH OF DAY... BUT RUC SOUNDINGS INDCT THAT ENOUGH MIXING SHUD OCCR DURG AFTN SO THAT PTLY CLDY FCST WILL BE ADEQUATE. CURRENT CLOUD-FREE CONDS OMTNS WILL BCM PTLY CLDY DURG AFTN AS HEATING CONTRIBUTES TO DVLPMNT OF SOME CONVECTIVE CLDNS. CURRENT LOW CHC POPS CNTRL MTNS WILL BE LEFT INTACT. WNDS THRU DEEP LYR VRY LGT SO ANY SHWRS THAT DVLP WILL RMN NRLY STNRY. NO IMPORTANT CHGS TO AFTN MAX TEMPS EXPCTD ATTM IN LATE MRNG FCST ISSUANCE. .GSP... GA...NONE. NC...NONE. SC...NONE. LGL sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 902 AM EDT MON APR 30 2001 SATELLITE LOOP SHOWS CLOUDS INCREASING OVER CAE CWA. AFTER LOOKING AT RUC AND MESOETA SURFACE AND H8 PROGS...HAVE DECIDED IT WILL REMAIN MOSTLY CLOUDY TODAY. NO PRECIP THOUGH. MODELS SHOW GOOD LOW LEVEL MOISTURE CONVERGENCE UNTIL ABOUT 00Z THIS EVENING. WILL CUT HIGH TEMPERATURES A COUPLE OF CATS AS WELL. WILL TRY TO BLEND MOSTLY CLOUDY FORECAST INTO BECOMING MOSTLY CLEAR THIS EVENING AND KEEP SAME LOW TEMPERATURES. OTHERWISE WINDS LOOK OK. FCSTID = 7 CAE 72 52 82 53 / 0 0 0 0 AGS 73 50 82 52 / 0 0 0 0 SSC 72 52 81 52 / 0 0 0 0 OGB 73 53 82 53 / 0 0 0 0 .CAE... GA...NONE. SC...NONE. TTH sc SOUTHEAST TEXAS FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 825 PM CDT MON APR 30 2001 WILL HAVE ONLY MINOR CHANGES TO CURRENT ZONES IN UPCOMING UPDATE AT 9 PM. LOW AMPLITUDE SHORT WAVE MOVING INTO THE NEIGHBORHOOD HAS BEEN UNABLE TO ENHANCE THE AIRMASS SHOWERS THAT ARE CURRENTLY IN THE MOST PROBABLE ACTIVE REGION - THE EAST SIDE OF THE 700 MB WAVE - AND HENCE BELIVE THAT ABSENCE OF SURFACE TRIGGER (OUTFLOWS NOT KICKING UP ANYTHING) AND RAPID SETUP OF SURFACE INVERSION WILL NIX POTENTIAL FOR PRECIP TONIGHT. BOTH 18Z ETA AND MOST RECENT RUC PHASE OUT EXISTING PRECIP BY 03-06Z AS WELL, SO WILL REMOVE POPS FROM FIRST PERIOD OF ZONES. IF MID LEVELS COOL AS ADVERTISED IN MODEL SOUNDINGS, WILL HAVE ANOTHER SHOT AT SEABREEZE/DIFFERENTIAL HEATING SHOWERS OR THUNDERSTORMS TOMORROW, SO WILL NOT CHANGE THE POP FORECAST IN THE SECOND PERIOD. OTHERWISE, NO OTHER CHANGES PLANNED TO CURRENT FORECAST. .HGX...NONE. 38/47/DH CLL BB 063/081 063/083 063 120 IAH EB 063/081 063/084 063 -20 GLS EB 070/078 070/079 070 02- tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 135 AM CDT TUE MAY 1 2001 IR AND RUC2 SHOW MID TROP TROF MOVING ACROSS IA...KS AND MO. REGIONAL RADARS SHOW SOME WEAK CONVECTION MOVING STEADILY EAST ACROSS MO. MAIN FORECAST CHALLENGE TODAY IS WHETHER TO MENTION CONVECTION AT ALL. MODELS ADVERTISE AS THE TROF GRADUALLY MOVES ACROSS THE FORECAST AREA TODAY...IT WILL ENCOUNTER A MARGINALLY UNSTABLE AIRMASS. CONVECTIVE INHIBITION WILL BE WEAKEST OVER THE EASTERN PART OF THE FA WITH TEMPS SLIGHTLY COOLER ALOFT THERE...WHILE WEAK MID LEVEL WAA DEVELOPS EAST ACROSS MO. SO WILL GO AHEAD AND INCLUDE SLIGHT CHANCE POPS FOR TODAY. AVN SHOWS NIL QPF WHILE ETA AND NGM TRY TO DEVELOP SOME SCANT QPF MAINLY OVER WRN KY WHERE THE AIRMASS SHOULD BECOME MOST UNSTABLE. FOR TONIGHT...TSCTS SHOW MOISTURE DEPARTING...WITH SKIES BECOMING MOSTLY CLEAR. TROF FORECAST TO LOSE ITS IDENTITY BY WEDNESDAY...SO GOES THE MOISTURE AND SUPPORT FOR ANY CONVECTION. WILL KEEP GOING FORECAST IN CHECK. NO CHANGES TO THE EXTENDED FORECAST. .PAH...NONE. ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 330 AM CDT TUE MAY 1 2001 SHORT WAVE MOVING INTO EAST TX TODAY APPEARS TO HAVE SPUN UP MORE THAN PREVIOUS RUNS SUGGEST...PARTICULARLY ON RUC. INSTABILITIES WILL YIELD LIFTED INDICES WELL BELOW ZERO ACROSS EAST TX AND WEAK LIFT NOTED AS WELL. A SLIGHT SHRINKING OF GROUND CLUTTER PATTERN OVERNIGHT MAY BE PRECURSOR OF DISSOLUTION OF LOW LEVEL INVERSION LAYER. SURFACE LOW PRESSURE WILL CONTINUE TO DEEPEN ACROSS PANHANDLE REGION OF TX/OK. HOWEVER...STRONG LOW LEVEL JET WILL REMAIN CONCENTRATED WEST OF THE AREA AND GUIDANCE NOT PLACING ANY POPS IN REMAINDER OF WEEK. ON EXTENDED...WILL TURN A PAGE BACK BY REINSERTING CHANCE OF THUNDERSTORMS FOR ALL BUT EASTERN PORTIONS OF AREA FOR SATURDAY AS PRETTY IMPRESSIVE INSTABILITY SETS UP. SHV 80/62/83/61 2110 MLU 82/60/85/61 1100 TXK 80/63/82/62 2110 TYR 79/63/82/62 2110 LFK 78/63/81/63 3210 .SHV...NONE. la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 530 AM EDT TUE MAY 01 2001 MAIN CONCERNS SCT -SHRA EAST HALF ZONES THIS MORNING...THEN SCT SHRA/TSRA TONIGHT INTO TUE MORNING WITH APPROACH OF CDFNT OVR THE NRN PLAINS. TODAY...WV LOOP/RUC ANALYSIS SHOWS STRUNG OUT SHRTWV MOVG EWD THRU MN ARROWHEAD/NW WI INTO IA WITH 88D LOOP INDICATING SCT SHRA ALG AND AHD OF ASSOC WK SFC TROF/BOUNDARY FM MQT-AUW-LSE. AS 850-500 MB Q-VECT DIV MAX AND ASSOC SUBSIDENCE MOVE IN BEHIND SHRTWV BTWN 12-18Z PER MODELS...EXPECT SCT SHRA TO END THIS MORNING OVR ZONES EAST OF MQT-DICKINSON. LOOK FOR SOME INCREASE IN WAA MID-HI CLDS LATE AFTERNOON IN ADVANCE OF NEXT APPROACHING SHRTWV/SFC CDFNT OVR NRN PLAINS. GIVEN 850 MB TEMPS WILL AROUND 3C COOLER THAN YESTERDAY EXPECT INLAND TEMPS ANYWHERE FM 5-10F COOLER (75 TO 80)...ALTHOUGH THIS WILL STILL BE 3-5F ABV MOS GUIDANCE. .TONIGHT...AS SHRTWV APPROACHES IN WSW FLOW THIS EVENING ASSOC CDFNT PUSHES INTO WRN FA THIS EVNG. 120 KT 3H JET MAX NOSES TOWARD WRN LAKE SUPERIOR WITH BEST LEXT EXIT REGION FORCING TO STAY MORE NW OF FA IN VICINITY OF DVLPG SFC LOW. AND ALTHOUGH ETA SNDGS ADVERTISING HIGH SBCAPES OF 1000-1500 J/KG OVR WRN CNTRL ZONES BY 03Z...BELIEVE LACK OF FAVORABLE JET DYNAMICS WILL LIMIT ANY STORMS FM BCMG SVR OVR U.P...SPC ALSO OF SAME MIND-SET KEEPING SLGT RISK TO SOUTH OVR WI AND SRN MN WHERE MCS FORMATION MORE LIKELY AT NOSE OF 50 KT 850 MB JET AND HIGHER SFC DWPNTS. STILL DWPNTS HIGH ENOUGH OVER U.P. TO WARRANT LIKELY POPS WEST AND CNTRL ZONES AS CDFNT COMES THRU. AS CLOSED LOW FORMS OVR WRN ONTARIO BTWN 06-12Z AND UPR TROF LESS PROGRESSIVE CDFNT WILL TEND TO SLOW OR STALL OUT AS IT APPROACHES ERN ZONES LATE TONIGHT. GIVEN UNCERTAINTY OF TIMING FOR ERN ZONES KEPT ONLY MENTION OF SCT SHRA/TSRA LATE. .WEDNESDAY...DWPNTS DRY OUT NICELY BEHIND FNT FM WEST. WENT PARTLY SUNNY OVER WRN ZONES. KEPT IN LOW CHC POP ERY MORNING FOR ANY LINGERING SCT SHRA ALG FNT FOR MQT-IMT. LEFT IN HIGHER CHC POP FOR ERN HALF ZONES WITH EVEN MENTION OF RUMBLE OF THUNDER GIVEN 200-300 J/KG CAPE ALG/AHD OF CDFNT. CNTRL/ERN ZONES SHOULD SEE AFT SUN AS CDFNT SLOWLY EXITS U.P. .WEDNESDAY NIGHT...CONTINUED DRYING/SUBSIDENCE ALF WITH WK SFC RDG BLDG BEHIND FNT. TOOK OUT CHC POPS FOR ALL ZONES AND WENT PARTLY CLOUDY. .MQT...NONE. VOSS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 955 AM CDT TUE MAY 1 2001 SHORT WAVE NOW MOVING THROUGH FORECAST AREA WITH CONSIDERABLE CLOUDINESS AND NO PRECIPITATION. CURRENT RUC MODEL INDICATING ENOUGH MOISTURE AND INSTABILITY FOR A FEW SHOWERS AND THUNDERSTORMS TO DEVELOP DURING THE HEAT OF THE AFTERNOON. NEW MESOETA MODEL SHOWING WEAK LIFT OVER EAST TEXAS AND NORTH CENTRAL LOUISIANA...THE QUESTION IS WILL THERE BE ENOUGH FOR PRECIPITATION. NEW MOS GUIDANCE INDICATING POPS OF 10S AND 20S. DECIDED TO KEEP ISOLATED CONVECTION IN FORECAST TODAY FOR ALL OF FORECAST AREA AND INCLUDE NORTH CENTRAL LOUISIANA AS WELL. SHV...NONE. 09 la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1137 AM EDT TUE MAY 01 2001 ANY CHANGES TO THE CURRENT ZONES FOR THIS AFTERNOON WILL BE MINOR. MAINLY CLOUDY SKIES ACROSS THE AREA THIS MORNING...ALONG WITH A FEW SHOWERS AND THUNDERSTORMS. SATELLITE LOOPS SHOWS THE CLOUDS MOVING STEADILY NORTHEAST. LOOKING UPSTREAM...DECENT SUNSHINE DEVELOPING. AM THINKING WE WILL SEE ABUNDANT SUNSHINE DEVELOPING THROUGH THE AFTERNOON...LEADING TO DESTABILIZATION. RUC SOUNDINGS ONLY GENERATE UNDER 200 J/KG CAPE...BUT THE RUC HAS THE SURFACE DEWPOINTS IN THE UPPER 40S. LATEST MESO PLOT HAS DEWPOINTS IN THE LOW TO MID 50S....THUS GREATER CAPE THAN THE RUC SHOULD BE REALIZED. THUS...AM THINKING WE WILL SEE SCATTERED THUNDERSTORMS DEVELOPING FROM MID AFTERNOON ON. AS FOR SEVERE WEATHER...THE THREAT APPEARS MINIMAL AT THIS TIME...BUT LOW WET BULB ZERO VALUES COULD LEAD TO SOME HAIL. IT ALL DEPENDS ON HOW MUCH WE DESTABILIZE. .GRR...NONE. mi NORTHERN GREAT BASIN FORECAST DISCUSSION NATIONAL WEATHER SERVICE ELKO NV 845 AM PDT TUE MAY 1 2001 12Z 300MB PLOT SHOWS 140KT JET STREAK ENTERED OREGON A FEW HOURS AGO. RUC MODEL THIS MORNING SHOWS THIS JET STREAK SAGGING TO THE SOUTH AS IT MOVES TO THE EAST. RIGHT REAR QUADRANT IS AFFECTING OUR AREA...ALLOWING CU TO POP UP...ESPECIALLY OVER THE MOUNTAINS. 12Z SOUNDING MODIFIED TO ALLOW FOR FURTHER MID-LEVEL COOLING AND SURFACE HEATING STILL DID NOT ALLOW SIGNIFICANT CONVECTION. H7 WINDS OF 35KT AND COLD AIR ADVECTION SHOULD MEAN WINDY CONDITIONS FOR MOST OF OUR AREA...WHICH THE MORNING PACKAGE HANDLES WELL. WINDS ARE CURRENTLY FROM THE SW...BUT EXPECT THEM TO SWITCH TO THE NW SOON ONCE THE NEW FRONT...CURRENTLY OVER SW ID AND NW NV...PASSES AND CAA BEGINS IN EARNEST. NO UPDATES ARE NECESSARY THIS MORNING. PRS .EKO...NONE. nv AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 935 AM EDT TUE MAY 1 2001 IR SAT/LTG DATA INDICATING SOME MORNING CONVECTION FIRING FROM E TN INTO WV. MODELS INDICATE 7 DEG/KM LAPSE RATES IN THIS REGION IN ASSOC WITH A WEAK SHORT WAVE AND POOL OF COOLER AIR AT 500 MB. THIS FEATURE WILL REMAIN WELL NORTH OF THE AREA TODAY AS IT SLOWLY DRIFTS EAST. MODEL SOUNDINGS INDICATE ATMOS WELL CAPPED OVER THE E CAROLINAS THIS AFTN...HOWEVER SOME FAIR WX CU WILL LIKELY POP INLAND AND ALONG THE SEABREEZE. WL TWEAK AFTN MAXES UP ALONG THE COAST WITH A COUPLE NEW HANOVER CO MESONET SITES ALREADY NEAR 70 DEGREES...OTHERWISE NO SIG CHANGES. CWF: RUC IS THE ONLY MODEL TO RESOLVE THE N/NE WIND DRIFT ON THE COASTAL WATERS THIS MORNING. WL KEEP WINDS PRIMARILY NE AND LIGHT FOR THE REST OF TODAY. FCSTID = 9 ILM 77 53 76 54 / 0 0 0 0 LBT 80 50 81 51 / 0 0 0 0 FLO 81 51 82 52 / 0 0 0 0 MYR 73 53 72 54 / 0 0 0 0 .ILM... NC...NONE. SC...NONE. TRA nc AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 923 AM MDT TUE MAY 1 2001 THE ZONE FORECAST HAS BEEN UPDATED TO INCLUDE A WIND ADVISORY FOR NORTHWESTERN INTO CENTRAL SD. 12Z U/A ANALYSIS COMBINED WITH RUC FORECAST SHOWS THAT A COMBINATION OF STRONG BOUNDARY LAYER WINDS... SUBSIDENCE...AND SUNSHINE SHOULD LEAD TO DEEP MIXING OVER THIS AREA. THERE MAY ALSO BE A FEW SHOWERS THIS AFTERNOON GIVEN SUFFICIENT HEATING AND MIXING. .UNR...WND ADVY TDY NWRN-CNTRL SD. MJB sd COASTAL BEND FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 1017 AM CDT TUE MAY 1 2001 EARLY PRESENCE OF 500HPA SHORTWAVE MAY PROVIDE SOME ASCENSION ASSISTANCE BUT DEPARTS RATHER QUICKLY. EXPECT ONLY ISOLATED TO WIDELY SCATTERED(NORTHEAST CWA WHERE BOUNDARY LAYER MOISTURE IS DEEPEST) CONVECTIVE ACTIVITY ASSOCIATED WITH THE SEA BREEZE BUT CAPPING INVERSION AND WEAK BOUNDARY LAYER FORCING WILL COUNTERACT. WILL LOWER POPS ACCORDINGLY. HIGHER 1000-850HPA THICKNESSES AND MESOETA/RUC SURFACE TEMPERATURES ARGUE RAISING MAXIMUM TEMPERATURES SOME. NO CHANGES TO THE MARINE PACKAGE. .CRP...NONE. 85/BB tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 255 PM CDT TUE MAY 1 2001 CU FIELD QUITE EXTENSIVE THIS AFTERNOON DUE TO MORE LOW LEVEL MOISTURE. A FEW SHOWERS DEVELOPED OVER SOUTH ARKANSAS BEFORE QUICKLY DYING. VORTICITY LOBE WITH SHORTWAVE SHOULD MOVE TO A LINE FROM EASTERN ARKANSAS...INTO CENTRAL AND EASTERN LOUISIANA...AND SOUTHEAST TEXAS BY LATE AFTERNOON ALONG UPPER TROUGH AXIS. RUC AND MESOETA SEEM TO BE OVERDOING QPF AMOUNTS FOR FORECAST AREA THIS AFTERNOON. UPPER TROUGH MOVES INTO THE LOWER MISSISSIPPI VALLEY TONIGHT AND WEDNESDAY AND SITS AND SPINS FORMING A CLOSED LOW SOUTH OF NEW ORLEANS. THIS COULD CAUSE A FEW SHOWERS AND STORMS OVER SOUTH LOUISIANA BUT PROBABLY NOT INTO CENTRAL LOUISIANA ON WEDNESDAY. 500MB RIDGE BUILDS NORTH FROM MEXICO THROUGH THE NEXT 48 HOURS. AN UPPER TROUGH DEVELOPS OVER THE ROCKIES WEDNESDAY AND FORMS A CLOSED UPPER LOW THURSDAY. A SHORTWAVE COMING ACROSS MEXICO INTO WEST TEXAS WEDNESDAY NIGHT AND THURSDAY AHEAD OF THE UPPER LOW SHOULD BRING SHOWERS AND THUNDERSTORMS INTO CENTRAL OKLAHOMA AND NORTH CENTRAL TEXAS BEFORE DYING OUT. AS UPPER LOW MOVES EAST SATURDAY AVN PUTS A VORTICITY MAXIMUM OVER NORTHEAST TEXAS. WILL KEEP A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS IN SATURDAY AND A CHANCE AGAIN SUNDAY. RAIN CHANCES WILL CONTINUE INTO TUESDAY AS MRF KEEPS THE SURFACE LOW TO THE WEST OF THE FORECAST AREA UNTIL MONDAY NIGHT AND TUESDAY. MAXIMUM TEMPERATURES SHOULD STAY ABOUT THE SAME THE NEXT SEVERAL DAYS WITH LOWS SLIGHTLY WARMER DUE TO LATE NIGHT AND EARLY MORNING LOW CLOUDINESS FORMING...ESPECIALLY OVER SOUTHERN SECTIONS. SURFACE WINDS WILL CONTINUE FROM THE SOUTH TO SOUTHEAST WITH GUSTY WINDS DURING THE DAY NORTHWEST SECTIONS. SHV 64/84/62/84 0001 MLU 62/83/62/84 1000 TXK 63/83/64/84 0001 TYR 65/85/64/84 0001 LFK 63/84/64/83 1001 .SHV...NONE. 09 la