EAST CENTRAL FLORIDA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 938 AM EDT SUN AUG 27 2000 CURRENTLY...SURFACE RIDGE AXIS EXTENDED ACROSS THE CENTRAL PENINSULA. RUC ANALYSIS AND WATER VAPOR SHOW H25 TROUGH ALSO IN ABOUT THE SAME LOCATION. LARGE AREA OF CONVECTION WAS OVER THE ATLANTIC ON EAST SIDE OF MID LEVEL CYCLONIC SHEAR AXIS. STEERING FLOW WAS MOVING MOST OF THIS CONVECTION ABOUT DUE NORTH EXCEPT IN THE SOUTH WHERE THERE WAS ENOUGH LOW LEVEL SOUTHEAST COMPONENT TO BRING A FEW SHOWERS ASHORE. FORECAST...TROUGH AXIS SHOULD MOVE VERY LITTLE AS SOUTHERN END WAS SHOWING SIGNS OF CUTTING OFF...WHILE NEXT MID LATITUDE SHORTWAVE WAS DIVING SOUTHEAST INTO MEAN TROUGH. HIGHEST POPS SHOULD BE OVER SOUTHERN SECTIONS WHERE GREATEST MOISTURE CONTINUES TO RESIDE. EXPECT THAT CONVECTION WILL GET GOING ALONG THE SEA BREEZE SOON IN THE SOUTH. SEA BREEZE BOUNDARY WILL BE SLOW TO MOVE INLAND DUE TO THE SOUTHERLY STEERING NEAR THE EAST COAST...BUT EVENTUALLY OUTFLOWS WILL KICK IT INLAND. WATER VAPOR LOOP SHOWING LESS EXTENSIVE MID LEVEL DRY AIR SO NORTHERN SECTIONS SHOULD SEE A FEW MORE CELLS FORM ALONG SEA BREEZE OR PROPAGATE INTO THE AREA...COMPARED TO YESTERDAYS VERY LOW COVERAGE. NOT PLANNING ON ANY CHANGES TO CURRENT FORECAST. MARINE...CONVECTION CURRENTLY DISTURBING THE WIND FIELDS. WITH LITTLE NORTHWARD PROGRESS IN SURFACE RIDGE AXIS...CURRENT 10 KNOT FORECAST LOOKS FINE. .MLB...NONE. PUBLIC/MARINE...LASCODY AVIATION/FIRE WX...VOLKMER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1035 AM CDT SUN AUG 27 2000 VISIBLE SATL SHOWS LOW CLOUDS/FOG IS SLOWLY ERODING FROM THE EDGES...BUT ITS HAVING A TOUGH TIME OF IT AS EASTERLY WINDS NOT REAL CONDUCIVE TO DRYING THINGS OUT. 14Z RUC SHOWS LOW LVL MOISTURE CONTINUING TO THIN ACROSS CEN IL DURING THE AFTN HOURS. SO WILL CONTINUE TREND OF SUNSHINE RETURNING TO THE AREA THIS AFTERNOON AND REMOVE FOG MENTION IN ZONES. MESO-ETA SHOWS WAA ONCE AGAIN RIDES OVER THE FRONTAL BOUNDARY ACROSS SRN SECTIONS OF IL THIS AFTN...SO EXPECT A FEW SHRA/TSRA TO SNEAK INTO SERN IL BY LATE AFTN. WILL KEEP A LOW POP GOING IN THIS AREA TO COVER THIS. .ILX...NONE. KETCHAM il AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 919 PM CDT SUN AUG 27 2000 FCST PROBLEM TGNT WL BE WHETHER ANY CONVECTION DVLPS OVNGT. STLT IMAGERY SHOWS SHRT WV DRIFTING ACRS NRN IA. IMPRESSIVE BACLIN ZN IN PLACE JUST TO OUR S. 01Z SFC ANLYS PLACES WRMFNT ALG LN JUST S OF KMKC AND KSTL METRO AREAS WITH 00Z H85 ANLYS SHOWING THAT FNT JUST TO THE N. THIS HAS RESULTED IN STG ISENT LIFT WITH 00Z RUC 310K SFC SHOWING OVR 150MB LIFT FM NWRN MO INTO IA. MSTR S OF WRMFNT LTD SO DO NOT XPC ANYTHING SGFNT BUT 00Z KOAX SOUNDING ONLY SHOWS CIN ARND 70 J/KG WITH PARCEL LIFTED FM 850MB. COMBINATION OF CONTD ISENT LIFT...MSTR ADVCTN AND WEAK DIFFERENTIAL PVA AHD OF SHRT WV SHOULD BE ENOUGH TO DMSH CIN AND DVLP WDLY SCT SHWRS/TSTMS AS LOW LVL JET STRENGTHENS. WL CONT MENTION OF PCPN OVNGT SCPLLY NERN HLF AHD OF MCV REMNANTS. ISENT LIFT HAS ALSO RESULTED IN ST DVLPG N OF WRMFNT PER 11-3.9 MICRON STLT IMAGERY SO WL MENTION MSTLY CLDY FA WIDE. TEMPS MAY BE A BIT WRM WITH ST DVLPG BUT WL LEAVE BE ATTM. .DSM...NONE. SMALL ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 715 AM EDT SUN AUG 27 2000 WILL UPDATE ZONES TO REFLECT LATEST TRENDS. FOR MACKINAC COUNTY...WILL DROP MENTION OF EARLY CLOUDS. ACROSS NORTHERN LOWER MICHIGAN...VISIBILITIES ARE NO WORSE THAN ONE MILE...UNRESTRICTED AT MANY OBSERVING STATIONS...SO WILL DROP MENTION OF MORNING FOG. ALSO...WILL RESTRICT MENTION OF MORNING DRIZZLE/SPRINKLES TO SOUTHEAST...WHERE RADAR IN CLEAR AIR MODE SHOWS A FEW RETURNS PUSHING WEST OFF LAKE HURON...ROTATING AROUND SHORTWAVE TO SOUTH OF REGION. FINALLY...EARLY LOOK AT 12Z KAPX RAOB SHOWS LOW LEVEL MOISTURE RATHER DEEP...EXTENDING THROUGH 300 FEET AGL...AND 06Z MESOETA/09Z RUC SUGGEST THAT LOW LEVEL MOISTURE WILL HANG ON EVEN LONGER THAN PREVIOUSLY THOUGHT...SO WILL RESTRICT MENTION OF MOSTLY SUNNY SKIES TO FAR NORTHERN/WESTERN COUNTIES THIS AFTERNOON...AND WILL INDICATE GRADUAL TRANSITION TO PARTLY SUNNY...MAINLY THIS AFTERNOON...ELSEWHERE. .APX...NONE. ROWLEY mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 930 PM CDT SUN AUG 27 2000 SFC HIGH NE OF LAKE SUPERIOR WITH RIDGING STILL BACK INTO ERN SD. RUC SHOWS THAT THE STABLE ATMOSPHERE ACRS MN WL REMAIN IN PLACE THRU MONDAY MORNING. THUS WL REMOVE MENTION OF STORMS FOR TONIGHT. REST OF FCST LOOKS GOOD...THO WILL TWEAK MINS AND WIND SPEEDS A TAD. COMPLEX PATTERN OF LOWS AND FRONTS FROM NRN HIGH PLAINS TO KANSAS. 12Z AVN DID THE BEST IN TERMS OF SFC PTTN...WITH NGM A CLOSE SECOND. AT THE SFC...MAJOR PLAYERS FOR MN WL BE THE STG COLD FRONT WHICH EXTENDED FROM CNTRL SASK TO SWRN MT AS OF 00Z...PAIR OF LOWS IN SD AND SERN MT THAT AVN SUGGESTS WILL CONSOLIDATE...AND WARM FRONT FROM CNTRL SD INTO NERN KS. CORRIDOR OF SIG MOISTURE HAS BEEN POOLING ALG AND JUST NORTH OF WRM FRONT...WITH NMRS DEWPOINTS AOA 75. 00Z UPPER AIR ANLYS SHOWS 90 KNOT JET AT GREAT FALLS MT. AVN INTENSIFIES JET TO 105 KNOTS BY MONDAY EVENING WITH CENTROID NEAR GFK. THUS WRN AND SRN MN WL BE IN RIGHT REAR QUAD EARLY MONDAY EVENING...AND OVER ENTIRE CWA BY LATE MONDAY NIGHT. BY 00Z AVN PLACES THE LOW AROUND MVE WITH WRM FNT XTNDG EWD...WHICH SEEMS REASONABLE GIVEN LOCATION OF SD AND MT LOWS ATTM. MANY PARAMETERS SEEM TO BE COMING TOGETHER FOR SVR WX MONDAY... HOWEVER ONE OPPOSING FACTOR ON THE AVN IS IT PROGS SFC LOW TO BEGIN WEAKENING MONDAY AFTERNOON. NOT SURE THIS IS CORRECT IN LIGHT OF STRENGTHENING JET CORE. ANOTHER POSSIBLE NEGATIVE FACTOR IS THE ATMOSPHERE BECOMING QUITE TROPICAL...CONDUCIVE TO HEAVY RAIN. AVN INDICATES AN AMAZING 2.1 PRECIPITABLE WATER OVER CNTRL MN BY MONDAY EVENING. MIGHT BE AN OVERNIGHT MCS DVLPG IN SC SD WHERE RUC SHOWS STRENGTHENING LO LVL JET POINTING AT SFC LOW...BUT EVEN THAT WOULD PROBABLY NOT REACH SRN MN WHERE AMS IS MORE STABLE. SO IT APPEARS THERE ARE MANY FACTORS POINTING TO SVR WX MONDAY AFTN/NIGHT. TIS BEEN PRETTY AMAZING TO SEE SO MANY STRONG JET CORES TRAIPSING ACRS THE US/CNDN BRDR FOR LATE SUMMER. .MSP...NONE TDK mn FORECAST DISCUSSION FOR EASTERN NORTH DAKOTA AND NORTHWEST MINNESOTA NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 1020 AM CDT SUN AUG 27 2000 FCST UPDATE WILL BE ISSUED BY 11 AM. CURRENT FCST ON TARGET...WITH TIMING OF DECREASE IN SHOWERS FM WEST THROUGH MIDDAY. RUC ANALYSIS AND SAT IMAGERY SHOW MAIN UPR SUPPORT NOW LIFTING THROUGH SRN MAN OR ACROSS ERN NE...WITH WEAK SUBSIDENCE FOLLOWING. HOWEVER...AREA OF DIVERGENCE ALOFT IS STEADILY SHIFTING EWD INTO THE DKTAS AND WILL SUPPORT ADDN CONVECTIVE ACTIVITY LATER TDY AND TNGT. SFC TEMPS SHOULD HAVE TIME TO RECOVER ACROSS ERN ND AS CLDS DECREASE THERE. BUT NW MN TEMPS MAY BE SLOWED...SO WILL ADJUST TEMPS DOWN SLIGHTLY IN ERN ZNS. .FGF...NONE. GUST nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 900 PM EDT SUN AUG 27 2000 IR/WV STLT LOOPS SHOW UPPER LOW OVER WEST VIRGINIA DROPPING SSEWD TOWARD WESTERN PARTS OF VIRGINIA AND NORTH CAROLINA. RUC AND MESOETA INDICATE UPPER LOW NEAR NC-VA BORDER BY 09Z WITH PVA EXTENDING INTO THE NORTHERN PART OF SOUTH CAROLINA INCLUDING THE NORTHEAST PART OF THE CAE CWA. MESOETA UPWARD LIFT IS ALSO LIMITED TO THIS AREA. MSAS MSP SHOWS THAT MESO-HIGH THAT DEVELOPED EARLIER IN THE DAY WITH THUNDERSTORM ACTIVITY IN EASTERN TENNESSEE MOVED SOUTH TO SOUTHERN GEORGIA INSTEAD OF MOVING SOUTHEAST INTO SOUTH CAROLINA AS PROGGED BY AN EARLIER MESOETA RUN. THIS KEPT THE SURFACE WINDS SOUTHWEST INSTEAD OF ALLOWING THEM TO BECOME SOUTHEAST AND THEREBY INCREASING THE LOW LEVEL WIND SHEAR. AS A RESULT...IT APPEARS THAT THE THUNDERSTORM ACTIVITY HAS ENDED FOR THE NIGHT OVER MUCH OF THE CAE CWA INCLUDING CAE-AGS-SSC-OGB. WILL HOLD ONTO A 20 PERCENT CHANCE OF THUNDERSTORMS TO THE NORTH PART INCLUDING LKR (LANCASTER) AND 27J (NEWBERRY). IN ADDITION...TEMPERATURES HAVE DROPPED OFF INTO THE 70S. WILL DROP LOWS TO AROUND 70 CAE-AGS AND INTO THE UPPER 60S NORTHERN PART OF CWA. FCSTID = 7 CAE 70 90 70 89 / 10 20 20 5 AGS 68 91 68 90 / 10 20 20 5 SSC 71 91 70 90 / 10 20 20 5 OGB 71 89 70 88 / 10 20 20 5 .CAE... GA...NONE. SC...NONE. TTH sc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE COLUMBIA SC 630 PM EDT SUN AUG 27 2000 THE THREAT OF SEVERE WEATHER HAS ENDED OVER CENTRAL SOUTH CAROLINA. MSAS SHOWS THE ATMOSPHERE MORE STABLE NOW WITH LIS -2/-3 AND CAPES BELOW 1000. RUC AND MESOETA KEEP ATMOSPHERE MARGINALLY UNSTABLE..SO WILL HOLD ONTO SOME POPS. FCSTID = 7 CAE 73 90 70 89 / 40 20 20 5 AGS 70 91 68 90 / 40 20 20 5 SSC 73 91 70 90 / 40 20 20 5 OGB 73 89 70 88 / 40 20 20 5 .CAE... GA...NONE. SC...NONE. TTH sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 655 AM EDT SUN AUG 27 2000 PLAN TO UPDATE ZONES TO RAISE POPS FROM 40 TO 60 AND LOWER TEMPERATURES FROM AROUND 90 TO UPPER 80S TODAY. A LARGE AREA OF SHOWERS AND TSTMS AHEAD OF THE OH VALLEY H5 SHORTWAVE IS NEARING THE NW PART OF SC AND SHOULD REACH THE FORECAST AREA LATE THIS MORNING. COVERAGE MAY DECREASE SINCE THE LATEST RUC SHOWS MAINLY H95 MOISTURE DIVERGENCE OVER THE AREA THROUGH 21Z. FCSTID = 5 CAE 88 72 91 69 / 60 20 30 20 AGS 88 71 92 69 / 60 20 30 20 SSC 88 73 91 71 / 60 20 40 20 OGB 88 73 91 71 / 60 20 40 20 .CAE... GA...NONE. SC...NONE. RJL sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 647 AM CDT SUN AUG 27 2000 CURRENT KOHX RADAR IMAGERY SHOWING NUMEROUS SHOWERS WITH EMBEDDED THUNDERSTORMS ACROSS THE CUMBERLAND PLATEAU. SATELLITE IMAGERY ALSO SHOWING CONTINUED DEVELOPMENT OF SHOWERS AND THUNDERSTORMS ACROSS CENTRAL MISSOURI...TRAINING SEWD INTO SOUTHERN IL AND WESTERN KY..AND THUS INTO CWA ALONG THETA-E RIDGE. RUC UPPER AIR DEPICTIONS SHOWING SHORTWAVE IN UPSTREAM FLOW ALSO. BECAUSE OF THESE DEVELOPMENTS...WILL GO WITH LIKELY POPS ACROSS THE CUMBERLAND PLATEAU REMAINDER OF TODAY. .BNA...NONE. 14 JBW tn COASTAL BEND FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 830 PM CDT SUN AUG 27 2000 LATEST RUC SUGGESTS SURFACE WINDS WILL BEGIN TO DECREASE IN THE NEXT FEW HOURS. THUS...WILL UPDATE WIND SPEEDS IN CURRENT PACKAGE. ALL ELSE LOOKS ON TRACK. TAH...71 .CRP...NONE. tx COASTAL BEND FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 240 PM CDT SUN AUG 27 2000 CURRENT...SHRA ACTIVITY THIS MORNING DISSIPATED SHORTLY AFTERNOON MAKING LANDFALL AS DRY AIR STILL DOMINATES. 12Z RAOB INDICATED 1.56 PWAT. 18Z GOES TPW SHOWS DRY AIR CONT OVR CWFA WITH EVEN DRIER AIR OVR THE GLFMEX. H2O VAPOR IMAGERY INDICATES DRY SLOT TRYING TO PUSH MORE DRY AIR INTO THE AREA...ALTHOUGH IT SEEMS TO BE FIGHTING H2 JET PUSHING MOISTURE FROM THE S INTO THE AREA FROM MEX. SHORT TERM...ETA FCST SOUNDINGS INDICATE PWATS REMAIN AT OR BELOW THIS MORNINGS READING. MODEL EVEN DROPS PWAT TO 1.35 AND 1.32 MON AND TUE RESPECTIVELY. AS H2 JET MOISTURE INFLUX MOVES W...SHUD SEE DRY SLOT MOVE CLOSE TO CWFA. VERT CROSS SECTIONS SHOW CONTINUATION OF LOW LEVEL MOISTURE...JUST ENUF FOR SOME EARLY MORNING CSTL SHOWERS. HOWEVER...ATMO DRIES RAPIDLY WITH HEIGHT. MEAN RH VALUES TO REMAIN ARND 50% THRU SHORT TERM. WITH DRIER AIR...WILL GO ABOVE FAN/FWC ON HIGHS AND BELOW ON LOWS. NO POPS IN THE SHORT TERM...IN FACT MOS SHOWS BELOW CLIMO POPS NXT 7 DAYS. NGM DOES SHOW WEAK H5 VORT MOVING THRU 12Z MON...BUT DOUBT COULD DO ANYTHING WITH DRY AIR. OTRW STRONG UPR RIDGE TO KEEP A STRANGLE HOLD ON REGION. LONG TERM...MODELS DIFFER IN LONG TERM OUTLOOK. MRF/ETA ARE TRYING TO PUSH H5 RIDGE...AT LEAST THE CENTER...TO THE EAST. NGM IS SLOWER...IF AT ALL. MRF EVEN SUGGESTS A BIG PATTERN CHANGE WITH DEEP MID LAT TROF DIGGING DOWN FROM PAC NW. TOO EARLY TO BUY THAT SOLUTION. AVN SHOWS RIDGE MOVES E...BUT SPLITS THE CENTER HOLDING ONE BACK OVR N TX. GOOD CONV ASSOCIATED WITH AN UPPER LOW IN GULF OFF S FL COAST. ALL MODELS TRY TO FORM AREA OF LOW PRES OFF THE E COAST OF FL...BUT DIFFER IN STRENGTH. IN FACT.... ECMWF AND UKMET HAVE NO SFC REFLECTION OF THE UPPER LOW. MRF SPLITS AREAS OF LOW PRESSURE...ONE GOES INTO THE GULF FCST TO MOVE TO THE LA COAST BY 00Z 9/2 WITH THE OTHER TO THE E FL. COAST. WILL HAVE TO WAIT AND SEE OVR NEXT COUPLE MODEL RUNS. MARINE...BOUNDARY LAYER MOISTURE REMAINS ADEQUATE THROUGH TUESDAY. WEAK SFC THETAE CONVERGENCE/SFC MOISTURE CONVERGENCE/SPEED CONVERGENCE/1000-850HPA DIVERGENCE Q-Q VECTOR CONVERGENCE WARRANTS ISOLATED SHRA THROUGH TUESDAY. NO TIMING REFERENCE NEEDED OFFSHORE BUT WILL RESTRICT TO LATE NIGHT/MORNING FOR THE BAYS. SFC ANTICYCLONE OVER THE WESTERN GLFMEX WILL CONTINUE TO SUPPORT DIURNALLY DRIVEN WINDS. LOWERING PRESSURES WITH CYCLONE NORTH OF TX WILL SERVE AS AN AFTERNOON/EVENING ENHANCEMENT(LESS SO TUESDAY). MODEL SOUNDINGS HINT AT A WEAK NOCTURNAL JET TONIGHT. WILL KEEP WINDS JUST SHORT OF SCEC THROUGH TUESDAY BUT WOULD NOT BE SURPRISED TO SEE BHP/PTA AT 17 OR 18 KTS FOR A TIME TONIGHT. WILL REVIEW LATEST RUC/MESOETA PRIOR TO RELEASE. UNCERTAINTY IN THE EXTENDED ARGUES VAGUENESS AT THIS POINT. MOST LIKELY INCREASE IN MOISTURE COMES LATE IN THE WEEK. LATEST IR IMAGERY AND SHORT-TERM MODELS LEND CREDENCE TO SFC CIRCULATION DEVELOPMENT INVOF FLORIDA BUT CARIBBEAN SEA NOT EVIDENT ATTM. PRELIMS FOLLOW... CRP UB 072/098 073/096 074 0000 VCT UB 071/098 073/097 073 0000 LRD UB 077/101 076/100 077 0000 ALI UB 073/100 074/100 075 0000 KEG...70 BB...85 .CRP...NONE. tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG, VA 848 PM EDT SUN AUG 27 2000 BUSY EVE ACROSS THE AREA WITH HAIL PRODUCING TSRA ABOUT OVERHEAD AND MOVING LITTLE. APCHG UPR LOW NOW OVER CNTRL WVA PRODUCING NEXT BATCH OF TSRA AND EXPECT IT TO SLIDE THRU SE WVA AND ACROSS MUCH OF WRN/SWRN VA OVER THE NEXT COUPLE OF HOURS. WITH ATMOS WEST OF THE BLUE RDG HAVING RECOVERED FROM EARLIER SHRA AND INCRSG LAPSE RATES PER COLD POOL WILL LKLY SEE CVRG HOLD TOGETHER A BIT LONGER TNGT. THIS SEEMS ON TRACK WITH GOING MESO-ETA/RUC WHICH TRACK UPR VORT SEWD THRU THE CWA OVRNGT AND INTO NC BY MORN. APRS BEST UVV TO EVENTUALLY SHIFT EWD ON PVA SIDE OF UPR SUPPORT WHICH SHOULD SHIFT SEWD OVRNGT. THUS PLAN TO BUMP UP POPS TO CAT EARLY ON THEN CUT TO CHC LATER ON. ELSW...GOOD CHC TO LKLY ON TAP AT LEAST TIL A WHILE AFTER MIDNIGHT. SOME SLIGHT TEMP ADJUST IN STORE. WILL ISSUE ZFP EARLY TO COVER INCRSG POPS ATTM. .RNK... NC...NONE. VA...NONE. WV...NONE. JH va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 245 AM CDT MON AUG 28 2000 FORECAST QUANDARIES...CLOUD COVER...PCPN CHANCES...AND TEMPS. CURRENT ASOS/AWOS OBSERVATIONS AND REGIONAL SATELLITE IMAGERY SHOWING MID TO HIGH LEVEL CLOUDINESS ACROSS THE MID STATE. UPPER LEVEL CLOUDINESS "STREAMING" SEWD FROM SW WI INTO THE MID STATE PER NWLY FLOW. MSAS/SURFACE HAND ANALYSES SHOWING SURFACE LOW OVER THE EASTERN PLATTE RIVER OF NE WITH STATIONARY BOUNDARY "ARCHING" INTO CENTRAL MI...THEN SEWD TO SE MS GULF COAST. SURFACE BOUNDARY OF NOTE ACROSS CENTRAL KY. DEWPOINT DEPRESSIONS AVERAGING 5 DEGREES OR LESS UNDER SOUTHERLY WINDS. CWA/S RUC MODEL SOUNDING PROFILES STILL SHOWING INSTABILITY INDICES SUPPORTIVE OF CONVECTION WITH PRECIPITABLE WATER VALUES IN THE 1.3-1.6 INCH RANGE. RUC/UPPER AIR CHART ANALYSES DEPICTING WIND FLOW STARTING TO VEER WITH HEIGHT MORE N THAN NWLY...UNLIKE PREVIOUS NIGHTS MODEL DEPICTIONS...AS UPPER LEVEL RIDGING INFLUENCES "TAKE HOLD" OF AREAL WEATHER PATTERN. 00Z ETA/NGM MON REGIONAL MODEL EVOLUTIONS THROUGH 00Z WED IN GENERAL AGREEMENT WITH WEAK SURFACE RIDGING...BUT CONTINUED AMPLIFICATION OF THE UPPER LEVEL RIDGING PATTERN OVER THE SOUTH CENTRAL U.S... LEAVING US AT THE MERCY OF PERIPHERY RIDGE CLOUDINESS AND CONVECTION POTENTIAL. AVN SEEMS TOO "AGGRESSIVE" IN DEVELOPMENT OF SURFACE FEATURES ACROSS THE REGION. BEST INITIALIZATION OF CURRENT WEATHER SCENARIO IS THE NGM...WHICH IS THE PREFERRED DISCUSSION MODEL. ETA MODEL SHOWING NO PCPN POTENTIAL THROUGH 00Z THU WITH NGM DEPICTING MEASURABLE RAINFALL IN SOME EXTENT ACROSS THE MIDSTATE FROM 18Z MON ON. SURFACE BOUNDARY TO OUR NORTH REMAINING ACROSS THE OHIO VALLEY REGION WITH STATIONARY BOUNDARY TO OUR WEST AND SOUTH "WASHING OUT". HOWEVER...SURFACE PATTERN REMAINING SOMEWHAT UNORGANIZED THROUGH THE PERIOD. PRECIPITABLE WATER EXPECTED TO REMAIN AOB 1.5 INCHES WITH MULTIPLE INSTABILITY INDICES STILL SHOWING POTENTIAL FOR ATMOSPHERIC DESTABILIZATION EVEN WITH THE DRY ETA SOLUTION. WOULD NOT EXPECT TO SEE CONVECTION ON A SCATTERED SCALE WITH NO MAJOR UPPER LEVEL DYNAMICS TO SPEAK OF. HOWEVER...CAN NOT RULE OUT THE POSSIBILITY OF AFTERNOON HEATING INFLUENCES CAUSING WIDELY SCATTERED SHOWERS AND THUNDERSTORM DEVELOPMENT LASTING INTO THE EARLY EVENING HOURS. MAIN FORECAST QUANDARY CENTERS AROUND HOW MUCH CLOUD COVER WILL OCCUR AROUND PERIPHERY OF UPPER LEVEL RIDGE CONTINUING TO INFLUENCE CWA? NGM MODEL RH FIELDS CONTINUING TO USHER IN LOW LEVEL MOISTURE TODAY WITH ADDITIONAL MID TO UPPER LEVEL MOISTURE AFTER 00Z TUE. COULD "SPLIT HAIRS" TRYING TO FORECAST THIS QUANDARY...BUT WITH SOME REMNANT OF NWLY FLOW CONTINUING THROUGH 00Z TUE...SKY CONDITIONS TODAY COULD REMAIN VARIABLE AND DEFINITELY ON TUE. WITH THIS IN MIND...WILL ADDRESS SKY CONDITIONS AS VARIABLE THROUGHOUT THE PERIOD. TEMPS...NGM MOS VALUES FOR HIGHS AND LOWS SEEM REASONABLE FOR THE PERIOD AND WILL LEAN ACCORDINGLY. PRELIMINARY NUMBERS FOR COORDINATION PURPOSES ONLY... BNA 091/071/093/070 2221 CSV 085/064/087/064 2221 .BNA...NONE. 14 JBW tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1130 AM EDT MON AUG 28 2000 LATEST VISIBLE SATELLITE IMAGERY HAS SHOWN THE WIDESPREAD FOG AND LOW CLOUDS WHICH AFFECTED THE SOUTHERN HALF OF MY CWA THIS MORNING HAVE QUICKLY DISSIPATED. THERE STILL IS...HOWEVER...A FEW LINGERING PATCHES OF FOG (KTVC STILL AT 2 1/2 MILES). ALL THE FOG WILL CONTINUE TO QUICKLY MIX OUT BY NOON. AN AREA OF FOG AND LOW STRATUS IS ALSO EVIDENT OVER CENTRAL LAKE MICHIGAN. THESE CLOUDS WILL TAKE MUCH LONGER TO MIX OUT (MID AFTERNOON)...YET THEY SHOULD STAY CLEAR OF THE SHORELINE. 12Z KAPX SOUNDING WAS SATURATED FROM THE SFC TO 950MB WITH A DRY LAYER ABOVE 900MB. I FEEL THAT THERE WILL BE AMPLY LOW-LEVEL MOISTURE THIS AFTERNOON TO SEE GOOD CU DEVELOPMENT. THE ONLY EXPECTION WILL BE ACROSS NE LOWER MI AS THE MARINE LAYER WILL PENETRATE INLAND UNDER THE LARGE-SCALE SOUTHEASTERLY FLOW. CU THAT DEVELOPS THIS AFTERNOON WILL BE FAIRLY FLAT AS A RATHER STRONG INVERSION WILL DEVELOP FROM 850 TO 700MB IN ADVANCE OF A FRONTAL BOUNDARY IN THE PLAINS. THIS CAPPING INVERSION WILL PREVENT ANY TYPE OF SHOWER/TSTM TO DEVELOP OFF OF LAKE BREEZE BOUNDARYS THIS AFTERNOON. THEREFORE...I WILL MAINTAIN A DRY AFTERNOON FORECAST. DROPPED HIGH TEMPS DOWN A BIT FROM PREVIOUS FORECAST ACROSS SOUTHERN TIER COUNTIES. TEMPS GOT A SLOW START TODAY WITH THE WIDESPREAD LOW-CLOUDS AND FOG THIS MORNING. MIXING TO 850MB ON RUC SOUNDINGS SUPPORT MID 70S TO NEAR 80 FOR MAX TEMPS. UPDATED ZFPAPX ALREADY ISSUED. .KAPX...NONE. CONSIDINE mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1030 AM EDT MON AUG 28 2000 12Z RAOBS/WV LOOP SHOW UPR RDG ACRS GRT LKS WITH VIGOROUS SHRTWV OVR SRN SASKATCHEWAN MOVG EWD THRU WRN TROF. SFC HI PRES OVR WRN QUEBEC WITH RDG AXIS XTNDG WWD THRU CWA INTO ERN MN. LOTS OF TSRA IN LLVL CNVGC AHD OF SFC FNT IN ND ASSOCIATED WITH UPR TROF AND UNDER COUPLED UPR JETS/H3 DIFFLUENCE ACRS NE ND/NW MN. CNVCTN HAS FIRED AT EDGE OF VERY STRG LID EVIDENT ON 12Z BIS SDNG...H7 TEMPS IN NRN PLAINS IN 10-12C RANGE. LOCAL 12Z SDNGS SHOW VERY STRG SUBSIDENCE INVRN BTWN H8-85 OVR MOIST LLVLS OVR CWA IN SLY FLOW ON BACK SIDE OF SFC HI. CONSIDERABLE LO CLD AND FOG TRAPPED UNDER INVRN AND MOST WDSPRD ACRS WCNTRL ZNS. EVEN THOUGH ERN CWA GENERALLY MCLR...LO CLD OFF LK MI APPEARS TO BE EXPANDING NWD JUST E OF ISQ PER LATEST VIS IMAGERY. MAIN FCST CONCERNS THIS MRNG ARE HANDLING OF LO CLD TDAY AND TSRA CHCS. 12Z RUC MODEL IN GOOD AGREEMENT WITH 06Z ETA SHOWING VIGOROUS SRN CAN SHRTWV AND BEST UPR DVGC/QVECTOR CNVGC LIFTING NEWD TOWARD WRN ONTARIO BY 00Z WITH SFC COLD FNT REACHING JUST W OF DLH EARLY THIS EVNG. SO UPR/SFC RDGING TO REMAIN PRETTY MUCH IN PLACE OVR CWA TDAY WITH WSWLY ALF GRDLY ADVCTG HIER H7 TEMPS OVR FA TO MAINTAIN STRENGTH OF SUBSIDENCE INVRN/CAP. STRG CAPPING WL PREVENT QUICK LIFTING OF LO CLD...BUT XPCT GRDL INCRS IN CIG HGT FM IFR THIS MRNG TO MVFR AND VFR THIS AFTN AS SOLAR HTG AND INCRSG PRES GRADIENT/SLY FLOW AHD OF APRCHG COLD FNT INCREASE MIXING BLO INVRN. ABUNDANT LO CLD WL HOLD SFC TEMPS DOWN QUITE A BIT BLO THE 90 DEGREES NECESSARY TO BRK THE CAP IN PLACE PER 12Z GRB SDNG. WL LWR FCST MAX TEMPS ESPECIALLY IN CENTER OF LO CLD AREA ARND IMT TO ACCOUNT FOR DCRSD INSOLATION PER LATEST LAMP GUIDANCE AND HI TEMPS UPSTREAM ON SUN. ALTHOUGH 06Z ETA DOES FCST WEAK CONVECTIVELY INDUCED WEAK H5 VORT LOBE THAT EMANATES FM NE ND CNVCTN THIS MRNG TO SWING INTO WRN LK SUP AFTR 21Z...LACK OF CONSIDERABLE SFC HTG/BNDRY SUG TSRA A NO GO FOR TDAY OVR CWA. FCST RUC/MESOETA SDNGS SHOW LARGE NEGATIVE AREA AT IWD PERSISTING THRU 00Z EVEN WITH 80/65. ARRIVAL OF COLD FNT TNGT WL INCRS TSRA CHCS W TO E. STRG WND SHEAR WL ENHANCE SVR THREAT...BUT LACK OF SGNFT DYNAMICS AND LINGERING CAP ASSOCIATED WITH HI H7 TEMPS AND UPR JET/VORT MAX STAYING FAR TO N SHUD MITIGATE THIS POTENTIAL. WL ISSUE ARBSPSMQT (WWUS35 KMQT) AFTR ARRIVAL/EXAMINATION OF 12Z ETA TO DETAIL SVR THREAT TNGT. .MQT...GALE WARNING EAST LAKE SUPERIOR TONIGHT. KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 650 AM EDT MON AUG 28 2000 10Z SURFACE ANALYSIS SHOWED A DEWPOINT BOUNDARY ACROSS SOUTHERN COUNTIES OF THE FORECAST AREA. LOW CLOUDS HAVE BECOME FAIRLY WIDESPREAD ALONG AND SOUTH OF THIS BOUNDARY...AND WITH SOUTHEAST FLOW JUST OFF THE SURFACE AROUND 15 KNOTS PER KAPX 88-D VAD WIND PROFILE... THESE LOW CLOUDS HAVE STARTED TO SURGE NORTH/NORTHWEST INTO THE FORECAST AREA. THUS...WILL UPDATE ZONES TO UPGRADE EARLY CLOUD COVER TO MOSTLY CLOUDY ACROSS THE SOUTH/SOUTHWEST...AND WILL EXTEND MENTION OF EARLY LOW CLOUDS FARTHER NORTH ACROSS THE REST OF NORTHERN LOWER MICHIGAN AND INTO EASTERN UPPER MICHIGAN AS WELL. ALSO...WILL DOWNGRADE SKY COVER FORECASTS FROM MOSTLY SUNNY TO PARTLY SUNNY AS STRATUS DECK THIS MORNING SHOULD TRANSLATE TO FAIRLY WIDESPREAD CUMULUS THIS AFTERNOON...AND THIS IS CONFIRMED BY 06Z MESOETA/09Z RUC MODEL SOUNDINGS/LOW LEVEL MOISTURE FORECASTS. CLOUD COVER COULD IMPACT HIGH TEMPERATURES TODAY...ESPECIALLY IF LOW CLOUDS LINGER THROUGH LATE MORNING...BUT NOT YET CONFIDENT ENOUGH TO LOWER FORECAST TEMPERATURES WITH THIS PACKAGE. .KAPX...NONE. ROWLEY mi SOUTH CENTRAL AND SOUTHEAST COLORADO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO 230 PM MDT MON AUG 28 2000 POPS TONIGHT THE BIGGEST QUESTION. CURRENTLY...WATER VAPOR SATELLITE LOOP AND RUC ANALYSIS SHOW SIG PV ANOMALY OVER CENTRAL NEW MEXICO...DRIFTING SLOWLY NWRD. DEEP DRY AIR AND SUBSIDENCE ON THE NORTH SIDE OF THIS SYSTEM SEEMS TO HAVE TEMPORARILY SUPPRESSED CONVECTION OVER MUCH OF THE CWFA...WITH THE "MONSOON" PLUME ORIENTED WEST TO EAST OVER THE NRN HALF OF CO. LOOKING NORTH...FAIRLY STG FRONTAL BOUNDARY NOSING INTO NRN CO...WITH MAIN PRESSURE RISE CENTER OVER SD INTO MN. TONIGHT...FRONTAL BOUNDARY SHOULD SLIP INTO AT LEAST NRN PTNS OF THE AREA BEFORE GOING STATIONARY...WHILE PV ANOMALY DRIFTS TOWARD THE CO/NM BORDER. MODELS PROG FAIRLY STG UPWARD MOTION OVER THE EASTERN SLOPES/PLAINS THROUGH 06Z...LIKELY ASSOCIATED WITH CONVERGENCE ALONG THE FRONT. BIGGEST NEGATIVE FOR CONVECTION IS THE DEEP DRY AIR/SUBSIDENT AREA OVER NRN NM...DRIFTING NWRD. BOTTOM LINE...SCT-WIDELY SCT POPS OK FOR TONIGHT...FWC POPS LOOKING A LITTLE TOO HIGH. LEAST CHC WOULD APPEAR TO BE OVER THE SE PLAINS... THOUGH WITH FRONT APPROACHING AND SEVERAL OLD BOUNDARIES IN PLACE... WON'T ELIMINATE CHCS ENTIRELY. SOMEWHAT CONCERNED THAT ANY CONVECTION THAT DOES DEVELOP WILL LINGER WELL PAST SUNSET...SIMILAR TO LAST NIGHT OVER NEW MEXICO. TUES...PV ANOMALY STILL OVER THE SE CORNER AS SFC FRONT WASHES OUT OVER THE EAST. DEEPEST MONSOON PLUME MAINLY WEST OF THE CWFA AS WELL. WILL TONE THINGS BACK TO JUST SLIGHT CHCS MOST EVERYWHERE... DESPITE FWC'S HIGHER POPS. SLIGHT COOLING OVER THE EAST...THOUGH FWC LOOKING TOO DRAMATIC AS USUAL...WILL GO WITH MAV NUMBERS. TUE NIGHT/WED...AGAIN...MONSOON PLUME TO THE WEST WITH LITTLE/NO UPWARD MOTION PROGGED ACROSS THE AREA. WILL GO WITH JUST THE USUAL SLIGHT CHCS FOR MTNS/ADJACENT PLAINS...AND DRY FOR THE EAST. SLIGHT UPTREND IN MAX TEMPS...ESPECIALLY EAST. EXTENDED...UPPER PATTERN IN A STATE OF TRANSITION LATE WEEK AND INTO THE WEEKEND. 12Z AVN AND 00Z MRF SUGGEST A SIGNIFICANT UPTURN IN PRECIP CHCS THURS...WITH ANOTHER WEAK FRONT OVER THE EAST...AND MOISTURE PLUME SHIFTING EWRD ACROSS THE AREA AS TROUGH DEEPENS OVER THE WEST COAST. HOWEVER...AFTER THU THINGS BECOME MORE MUDDLED... ESPECIALLY CONCERNING MOISTURE. MRF SUGGEST SW FLOW TO SHUNT MOST MOISTURE EASTWARD FRI...BUT THEN DEVELOPS ANOTHER "PLUME" OVER THE AREA SATURDAY. GIVEN UNCERTAINTY...WILL CONTINUE THE BROADBRUSH OF PRECIP CHCS INTO SAT...WITH FAIRLY PERSISTENT TEMPS. QUICK PEEK AT THE REMAINDER OF THE HOLIDAY WEEKEND WOULD SUGGEST A FAIRLY SIG FROPA FOR ALL THE CWFA SUN/MON AS WRN TROUGH MOVES INLAND. STILL A LONG WAY OFF AND PLENTY OF TIME FOR MODEL FLIP-FLOPS...SO NOT TOO EXCITED YET. .PUB...NONE. PETERSEN co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 245 PM CDT MON AUG 28 2000 BIGGEST CHALLENGE WILL BE CHC OF RW/TRW LATE THIS AFTERNOON AND EARLY EVENING ACROSS EXTREME NE-E SECTIONS. AT EARLY AFTERNOON A STATIONARY FRONT LAY NW-SE ACROSS THE CENTRAL SECTIONS OF OUR CWA. ACCORDING TO THE RUC/ETA/AVN THE FRONT WILL SHOW ONLY MINIMAL MOVEMENT TO THE NORTHEAST OVER THE NEXT 12-18 HOURS. IN THE MEANTIME THOUGH...MODELS BUILD BOTH H7 & H5 RIDGES ACROSS THE FA AND SHOW WARM AIR ADVECTION AT BOTH THE H8 & H7 LEVELS. CONVECTION CURRENTLY OVER EXTREME SOUTHEASTERN SECTIONS OCCURRING JUST TO THE NORTH AND EAST OF THE SFC BOUNDARY...IN AN AREA OF ISENTROPIC UPGLIDE...AND WHERE H7 TEMPS ARE 11C OR COOLER. AT THE MOMENT AM LEANING AGAINST 1ST PERIOD CHC POPS EVERYWHERE EXCEPT EXTREME NE-E SECTIONS EVEN THOUGH SFC BOUNDARY IN VCNTY... BECAUSE BY 00Z MODELS WARM MID LEVEL TEMPS >11C...SHIFT DEEPEST MOISTURE TO THE NORTHEAST...AND I315 UPGLIDE WEAKENS. MODELS HOWEVER SHOW GOOD I315 PRESSURE ADVECTION ACROSS EXTREME NE-E SECTIONS. BEYOND THE 1ST PERIOD SEE NO SHORT TERM PROBLEMS AS UPPER RIDGE PLANTS ITSELF ACROSS FA. FOR EXTENDED...AVN AND MRF BOTH SHIFTING UPPER HIGH OFF EAST COAST ALLOWING UPPER LOW TO ROTATE NORTHWEST TOWARD FA. ALTHOUGH THIS IS AN UNUSUAL PATTERN...SEE NO REASON TO DISPUTE AT THIS TIME...SO WILL MENTION POPS ON FRIDAY AND SATURDAY. .PAH...NONE. PACKETT ky