AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 248 PM MDT MON AUG 2 2004 .SHORT TERM (TONIGHT THROUGH TUESDAY NIGHT)... SUBTROPICAL UPPER HIGH REMAINS CENTERED OVER WEST TEXAS THIS AFTERNOON AND AN OPEN WAVE TROUGH IS MOVING NORTHEAST ACROSS CALIFORNIA. SOUTHWEST FLOW BETWEEN THESE SYSTEMS HAS TRANSPORTED MONSOON MOISTURE ACROSS EASTERN UTAH AND WESTERN COLORADO. THE GOES SOUNDER SHOWS PRECIPITABLE WATER VALUES OF ONE INCH HAVE ADVECTED AS FAR NORTH AS NORTHWEST COLORADO AS OF 20Z. CONVECTION HAS BEEN SLOW TO DEVELOP DUE TO THE EXTENSIVE CLOUD SHIELD WHICH HAS BEEN SPREADING ACROSS THE AREA FROM SOUTH TO NORTH. THUNDERSTORMS MOST NUMEROUS THUS FAR ALONG THE ROAN-TAVAPUTS PLATEAU AREA...OR GENERALLY ALONG THE NORTH EDGE OF THE DEEPER MOISTURE WHERE SUNSHINE HAS BEEN ABLE TO DESTABILIZE THE AIRMASS TO A GREATER EXTENT. CONCERN FOR TONIGHT IS AREAL COVERAGE OF PRECIPITATION AND POTENTIAL FOR SOME STRONG STORMS THIS EVENING. BELIEVE THAT THE CLOUD SHIELD OVER THE AREA WILL CONTINUE TO HOLD DOWN CONVECTION SOMEWHAT FOR THE REST OF THE AFTERNOON, BUT SATELLITE DATA AND THE RUC ANALYSIS SHOW SOME WEAK WAVES UPSTREAM AND A WEAK UPPER JET SEGMENT OVER THE GREAT BASIN WHICH WILL ADD SOME DYNAMICS TO THE PICTURE. THERE ALSO APPEARS TO BE A WAVE ASSOCIATED WITH A CLUSTER OF STORMS OVER NEW MEXICO WHICH WILL LIKELY AFFECT SOUTHWEST COLORADO THIS EVENING. ENOUGH SPEED SHEAR ALOFT TO SUPPORT SOME STORM ORGANIZATION, MAINLY OVER NORTHEAST UTAH AND NORTHWEST COLORADO WHERE SMALL HAIL AND GUSTY WIND POTENTIAL APPEARS TO BE THE GREATEST. HARD TO PICK OUT ANY PARTICULAR AREA FOR PRECIPITATION TO FOCUS BUT THE ETA DOES SUGGEST THAT THE SAN JUANS WILL BE A FAVORED AREA. THIS SEEMS REASONABLE GIVEN THE APPARENT WAVE TO THE SOUTH AND THE POTENTIAL FOR WEAK OROGRAPHIC FORCING IN THIS AREA. STEERING CURRENTS SHOULD PRODUCE ENOUGH STORM MOTION TO KEEP THE FLASH FLOOD THREAT FROM BEING TOO BIG OF A CONCERN, ALTHOUGH TRAINING STORMS WILL NEED TO BE MONITORED AS WELL AS THE SAN JUANS IF THE WAVE OVER NEW MEXICO GENERATES EXTENSIVE CONVECTION OVER THE AREA THIS EVENING. TYPICAL OF A MONSOON REGIME...EXPECT SOME SHOWERS AND ISOLATED THUNDERSTORMS TO LINGER AFTER MIDNIGHT TONIGHT. HIGH LEVELS OF MOISTURE IN THE ATMOSPHERE WILL ACT TO INSULATE THE BOUNDARY LAYER AND KEEP OVERNIGHT MIN TEMPERATURES MILD. THE WAVE CURRENTLY OVER CALIFORNIA WILL WEAKEN AND MOVE ACROSS THE EASTERN GREAT BASIN AND NORTHERN ROCKIES TUESDAY. MODELS ARE IN AGREEMENT THAT THIS WILL BRING DRIER AIR TO EASTERN UTAH AND WESTERN COLORADO. AS A RESULT, MODEL GUIDANCE PROBABILITIES OF PRECIPITATION ARE MINIMAL ACROSS THE FORECAST AREA TUESDAY. BELIEVE THIS IS A LITTLE OVERDONE, SO WILL SHOW A DECREASED CHANCE OF PRECIPITATION TUESDAY BUT STAY ABOVE WHAT GUIDANCE SUGGESTS. TEMPERATURES SHOULD BE WARMER TUESDAY DUE TO LESS CLOUDS, ESPECIALLY ACROSS THE FOUR CORNERS AREA WHERE CURRENT TEMPERATURES ARE ABOUT 10 DEGREES COOLER THAN YESTERDAY AT THIS TIME DUE TO CLOUD COVER. WILL FORECAST CONVECTION TO DIMINISH TUESDAY EVENING WITH NORMAL DIURNAL STABILIZATION OF THE BOUNDARY LAYER. COOLER MINIMUM TEMPERATURES TUESDAY NIGHT WITH BETTER CONDITIONS FOR RADIATIONAL COOLING. LINDQUIST .LONG TERM (WEDNESDAY THROUGH MONDAY)...UPPER LEVEL RIDGE OF HIGH PRESSURE WILL SIT OVER NEW MEXICO AND COLORADO WITH SEVERAL DISTURBANCES ROTATING CLOCKWISE ACROSS EASTERN UTAH AND WESTERN COLORADO. TOWARD THE END OF THIS PERIOD...DRIER AND VERY WARM CONDITIONS WILL DEVELOP. WEDNESDAY...MODELS AGREE THAT A DRIER AIR MASS WILL AFFECT THE AREA WITH THE AXIS OF DEEPEST MOISTURE SEEN FROM CENTRAL UTAH TO SOUTHEAST ARIZONA. MID LEVELS WILL WARM ABOUT 2C FROM TUESDAY...SO THE COMBINATION OF DRIER AIR AND WARMER TEMPS ALOFT SHOULD INHIBIT CONVECTION FOR MOST AREAS. RESIDUAL MOISTURE AND DAYTIME HEATING WILL WILL SUPPORT ISOLD AFTERNOON THUNDERSTORMS OVER THE MOUNTAINS... BUT DON'T EXPECT MUCH ACTIVITY ELSEWHERE. H7 TEMPS WARM TO AROUND +17C AT GJT SO EXPECT VERY WARM CONDITIONS (UPPER 90S AT GJT). THURSDAY...RIDGE AXIS REMAINS JUST TO THE EAST OF FORECAST AREA. BOTH THE ETA/GFS SHOW AN INCREASE IN MOISTURE ACROSS THE AREA ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE MOVING UP FROM EASTERN ARIZONA. GFS IS MUCH MORE AGGRESSIVE WITH MOISTURE AND WAVE...HOWEVER GIVEN OCCASIONAL CONVECTIVE FEEDBACK ISSUE...AM CAUTIOUS WITH GFS SOLUTION AT THIS TIME. EITHER WAY...AGREE WITH TREND AND WILL INCREASE CLOUDS AND POPS...AND LOWER TEMPS SEVERAL DEGREES FROM WEDNESDAY. FRIDAY THROUGH MONDAY...RIDGE AXIS WILL ORIENT ITSELF SW-NE ACROSS THE FOUR CORNERS AND MOVE LITTLE INTO EARLY NEXT WEEK. AFTER THURSDAY'S DISTURBANCE...SEE NO SIGNIFICANT WEATHER FEATURE OR SURGE OF MOISTURE AFFECTING THE AREA. ISOLD-SCT AFTN/EVE THUNDERSTORMS MAINLY IN THE MOUNTAINS WILL PREVAIL. BY MONDAY...DRIER AIR MOVES IN AS RIDGE FLATTENS. WILL REMOVE ANY MENTION OF POPS AND KEEP VERY WARM TEMPERATURES GOING IN FORECAST. DJN.83 && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...NONE. .UT...NONE. $$ TAL/DJN co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1105 AM EDT MON AUG 2 2004 .DISCUSSION... THE MAIN CONCERN WITH THIS UPDATE IS THE POTENTIAL FOR SHOWERS AND THUNDERSTORMS THIS AFTERNOON. WATER VAPOR IMAGERY AND RUC/ETA SHOWING A LOW OVER HUDSON BAY FORMING A LONGWAVE TROUGH. ANOTHER LOW IS OFF THE COAST OF ALASKA...AND A RIDGE OVER THE CANADIAN ROCKIES SEPARATING THESE TWO. THE FLOW ACROSS THE NORTHERN PLAINS IS FROM THE WEST NORTHWEST. A LARGE MCS IS OVER MINNESOTA THIS MORNING...IN AREA OF AN 850MB THETA-E RIDGE. A WEAK SHORTWAVE MOVED THROUGH SOUTHERN WISCONSIN AND THE U.P. OVERNIGHT AND GENERATE A FEW STRONG THUNDERSTORMS AROUND MANISTIQUE. SURFACE ANALYSIS SHOWING A RIDGE OVER SOUTH CENTRAL CANADA...A TROUGH OVER STRETCHING FROM JAMES BAY THROUGH WESTERN LAKE SUPERIOR TO A LOW OVER SOUTH DAKOTA. THE FLOW WILL TAKE THE MCS OVER NORTHERN WISCONSIN TO THE SOUTHEAST AND KEEP IT SOUTH OF THE FORECAST AREA THIS AFTERNOON. SURFACE DEW POINTS AND THE THETA-E RIDGE WILL WEAKEN THROUGH THE AFTERNOON AS IT SLIDES SOUTHEAST. ETA IS DEVELOPING CAPE OF AROUND 1200 J/KG ALONG THE NORTHERN LAKE MICHIGAN SHORE BY LATE AFTERNOON. RUC IS DEPICTING SURFACE DEW POINTS AROUND 72F THIS AFTERNOON OVER SOUTH CENTRAL U.P...WHEREAS THE OTHER MODELS SHOWING DEW POINTS INTO THE MID AND UPPER 60S. RUC ALSO SUGGEST CAPES INTO THE 2000+ J/KG RANGE. COMPARISONS OF CURRENT OBSERVATIONS SUPPORT THE LOWER CAPE AND SURFACE DEW POINT CONDITIONS. ALSO EXPECT THE STRONG THUNDERSTORM ACTIVITY OVER WISCONSIN WILL ROB THE FORECAST AREA OF SOME OF THE INSTABILITY AND MOISTURE. STILL CONDITIONS LOOK FAVORABLE FOR SCATTERED SHOWER AND THUNDERSTORMS THIS AFTERNOON...BUT DO NOT EXPECT ANY SEVERE AT THIS TIME. TRAJECTORY FORECAST SUGGEST TEMPERATURES INTO THE MID 80S THIS AFTERNOON. GUIDANCE WILL HAS LOWER MAX TEMPS. BLOW OFF OF THE MCS OVER WISCONSIN WILL BLANKET THE FORECAST AREA AND SHOULD LIMIT TRADITIONAL HEATING AND THE INSTABILITY WILL GENERATE MORE CLOUDS. THUS FAVOR THE GUIDANCE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1045 AM EDT MON AUG 2 2004 .UPDATE... COULD BE AN INTERESTING AFTERNOON AS WE ARE CLOSELY MONITORING UPSTREAM ACTIVITY. SATELLITE PICTURES REVEAL AN IMPRESSIVE COMPACT MCV ENTERING NORTHERN WISCONSIN WITH A SEPARATE COMPLEX CROSSING OVER THE MISSISSIPPI RIVER INTO ILLINOIS. WIND PROFILERS UPSTREAM HAVE THE BEST LOW LEVEL JET REMAINING WEST OF THE CURRENT CONVECTION THEREFORE, THIS ACTIVITY SHOULD WEAKEN WITH THE EXCEPTION OF THE NORTHERN WISCONSIN ACTIVITY. WE CURRENTLY HAVE SUNSHINE WITH EARLY MORNING AC/CS ALL HAVE DISSIPATED AND WE ARE HEATING UP FAST! 12Z SOUNDINGS SHOWS HIGHS THIS AFTERNOON INTO THE UPPER 80S AND COUPLE THAT WITH UPPER 60 DEWPOINTS TO AROUND 70, WE HAVE CAPES CLOSE TO 3500 J/KG. OUR LOCAL SEVERE WEATHER CHECK LIST ALL POINTS TOWARD A PROGRESSIVE DERECHO BUT WE ARE MISSING ON KEY ELEMENT... WIND. FORECAST PROFILES CONTINUE TO HAVE WEAK WINDS ALOFT ACROSS THE GREAT LAKES BUT WE HAVE SEEN FROM TIME TO TIME THAT THESE MCV DO HAVE A WAY TO CREATE THERE OWN ENVIRONMENT. AT THE SURFACE WE HAVE A QS-FRONT ACROSS WISCONSIN THAT OUR NEW EXPERIMENTAL WRFGLR AND WRFXX INCLUDING THE WRFRUC AND BRING TOWARD THE TRI-CITIES AND THUMB TOWARD 21Z. THIS IS WHERE THE BEST CONVERGENCE IS FORECAST ALONG WITH THE HIGHER CHANCE FOR CONVECTION THIS AFTERNOON. BUT WE WILL HAVE ANOTHER SHOT WITH LAKE BREEZE DEVELOPMENT TO AID IN FURTHER CONVERGENCE. WE WILL HOLD ONTO OUR CHANCE TRW BUT RAISE OUR SEVERE WEATHER POTENTIAL GRAPHIC TO SLIGHT. AT THIS TIME, WE ARE PLANNING AN 18Z SOUNDING. BGM && .PREV DISCUSSION... ISSUED AT 355 AM EDT 00Z RAOBS/WATER VAPOR LOOP SHOW UPPER HIGH OVER THE SOUTHERN PLAINS...WITH FAST GENERAL WESTERLY FLOW ACROSS THE NORTHERN CONUS INTO THE GREAT LAKES. SURFACE ANALYSIS SHOWS LOW OVER SOUTH DAKOTA...WITH A FRONT EXTENDING ACROSS MINNESOTA TO THE NORTHERN GREAT LAKES. REGIONAL RADARS SHOW A FEW SHOWERS REDEVELOPING ACROSS WISCONSIN/UPPER MICHIGAN...BUT NOTHING SO FAR ACROSS LOWER MICHIGAN. IR SATELLITE SHOWS SOME MID CLOUDS THICKENING AS THEY MOVE ACROSS THE STATE...WITH SOME LOWER CLOUDS DEVELOPING ACROSS THE CWA AS WELL. MAIN FORECAST FOCUS CONTINUES TO BE WITH PRECIP CHANCES THROUGH MID WEEK. ETA/GFS CONTINUE TO HAVE ISSUES WITH SMALL-SCALE FEATURES EMBEDDED IN THE FAST FLOW...AS WELL AS PROBLEMS HANDLING THE CONVECTIVE DEVELOPMENT ASSOCIATED WITH THEM. GFS STILL SERIOUSLY CONTAMINATED WITH CONVECTIVE FEEDBACK...ESPECIALLY WITH THE WAVE TUESDAY NIGHT/WEDNESDAY. WILL LEAN THE FORECAST TOWARD THE ETA... EVEN THOUGH IT HAS NOT BEEN ALL THAT STABLE RUN TO RUN EITHER. INTERESTINGLY ENOUGH THOUGH...CANADIAN AND UKMET BOTH DEVELOP FEATURES SIMILAR TO THE GFS...BRINGING A SWATH OF HEAVY PRECIP AS FAR NORTH AS SOUTHERN LOWER MICHIGAN DURING THE SAME GENERAL TIME FRAME. FOR TODAY...00Z ETA/03Z RUC ARE SLOWER THAN EARLIER RUNS BRINGING HIGHER THETA-E AIR INTO THE STATE. THETA-E TROUGH ACTUALLY INITIALIZED JUST UPSTREAM THIS EVENING...WITH NEGATIVE ADVECTION/STABILITY SQUASHING ANY STORMS THAT TRIED TO MOVE EAST OUT OF WISCONSIN EARLIER IN THE EVENING. ETA/RUC SHOW THETA-E RIDGE MOVING ACROSS LOWER MICHIGAN TODAY. ADDITIONAL MID-CLOUD DEVELOPMENT ACROSS LAKE MICHIGAN/WESTERN LOWER COULD BE A SIGN OF THE ADVECTION KICKING IN. STILL CONCERNED THAT LAPSE RATES COULD STEEPEN ENOUGH BY SUNRISE TO LEAD TO A FEW SHOWERS/THUNDERSTORM. HOWEVER WITH AIRMASS WEAKLY CAPPED PER DTX SOUNDING AND 700MB THETA-E RIDGE FARTHER UPSTREAM...WILL START THE FIRST PERIOD OUT DRY. DEEPER MOISTURE INCREASES DURING THE DAY...AS DOES INSTABILITY WITH DAYTIME HEATING AND STEEPENING LAPSE RATES. FRONT/TROUGH OVER UPPER MICHIGAN/WISCONSIN IS SOMEWHAT DIFFUSE...BUT DOES MOVE INTO NORTHERN LOWER BY 00Z THIS EVENING WITH AN INCREASE IN LOW-LEVEL CONVERGENCE WELL AHEAD OF IT. WILL KEEP CHANCE POPS GOING FOR THUNDERSTORMS THIS AFTERNOON. WITHOUT OVERNIGHT/MORNING CONVECTION TO STABILIZE THINGS INITIALLY...INSTABILITY REALLY SOARS THIS AFTERNOON. 00Z ETA/06Z RUC BOTH HAVE CLOSE TO 3000J/KG SB-CAPE...WITH LIFTED INDEX -7C ETA TO -10C RUC BY 18Z THIS AFTERNOON. WIND FIELD IS NOT THAT IMPRESSIVE... NEARLY UNIDIRECTIONAL WITH LITTLE SPEED SHEAR EVEN /BASICALLY 15-20KTS THROUGH 500MB/. HOWEVER GIVEN THE DEGREE OF INSTABILITY... PULSE SEVERE MAY BE A CONCERN THIS AFTERNOON. THE WEAK SURFACE TROUGH/FRONT DROPS SOUTHEAST INTO THE CWA TONIGHT...PROVIDING ADDITIONAL LOW-LEVEL CONVERGENCE FOR CONVECTIVE DEVELOPMENT. ADDITIONAL UPPER-LEVEL SUPPORT AS WELL SEEN BY AN INCREASE IN 850-500MB QVECTOR CONVERGENCE...AHEAD OF A VORT THAT IS CURRENTLY OVER THE DAKOTAS. CURRENT MODEL RUNS ARE NOT AS IMPRESSIVE WITH ORGANIZED MCS POTENTIAL AS EARLIER...HOWEVER GIVEN LINGERING INSTABILITY AND SLIGHTLY BETTER WIND FIELD CLOSER TO THE SURFACE BOUNDARY...WILL KEEP SCATTERED POPS GOING OVERNIGHT. MODEL DISCREPANCIES BECOME MORE APPARENT ON TUESDAY/TUESDAY NIGHT... WITH THE EVENTUAL PLACEMENT OF THE SURFACE FRONT AS WELL AS POTENTIAL WAVES THAT DEVELOP ALONG IT. ETA HAD BEEN TRENDING FARTHER SOUTH WITH THE FRONT ON TUESDAY...BUT WITH THE CURRENT RUN A TAD FARTHER NORTH. GFS AS MENTIONED ABOVE CONTINUES TO HAVE FEEDBACK PROBLEMS...AND IS CONSEQUENTLY TOO STRONG WITH A SURFACE WAVE THAT PULLS THE FRONT NORTH AGAIN. AT THE SAME TIME...UPPER LOW OVER NORTHERN CANADA DROPS INTO QUEBEC...ENHANCING THE NORTHWESTERLY COMPONENT TO THE FAST NORTHERN STREAM FLOW. ETA 500MB HEIGHT FALLS PICK UP MORE BY TUESDAY NIGHT...FURTHER SUPPRESSING CONVECTION TO THE SOUTH. CURRENT GRIDS HAVE TUESDAY/TUESDAY NIGHT DRY...AND WILL STICK WITH THAT FOR NOW. CURRENT RUN SHOWS BETTER SURFACE-BASED INSTABILITY...BUT NO DEEP MOISTURE STILL. COULD SEE SOMETHING HAPPENING ACROSS THE SOUTHERN CWA ON TUESDAY...BUT GIVEN MODEL PERFORMANCE AND CONVECTIVE HANDLING...NOT ENOUGH EVIDENCE TO ADD IT BACK IN. WILL ALSO REMOVE POPS FROM WEDNESDAY. WHILE IT IS ODD THAT GFS/CANADIAN/UKMET ALL BRING QPF BACK AS FAR NORTH AS LOWER MICHIGAN TUESDAY NIGHT/WEDNESDAY...NOT CONFIDENT AS TO THEIR HANDLING OF THE PATTERN. WITH FALLING HEIGHTS AND ENHANCED NORTHWESTERLY FLOW... WOULD EXPECT IT TAKE A DECENT SHORTWAVE TO LIFT A WAVE BACK THIS FAR NORTH. WITH THE STRONG MODEL-DEPICTED VORT A RESULT OF CONVECTIVE FEEDBACK...FEEL A WEAKER ONE WOULD ONLY SUPPORT CONVECTION CLOSER TO THE SURFACE BOUNDARY. SURFACE RIDGE SHOULD DOMINATE ACROSS LOWER MICHIGAN. && .DTX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ BRAVENDER EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1010 AM EDT MON AUG 2 2004 .SHORT TERM (REST OF TODAY)... UPPER LEVEL TROUGH ANALYZED JUST UPSTREAM AT 12Z...WITH TS ALEX OFF COAST. VIS SATELLITE IMAGERY NOT SHOWING SUBSIDENCE BELT NW OF ALEX...AND RADAR SHOWING PRECIPITATION JUST TO N OF AREA. WILL RAISE POPS N NC FOOTHILLS LATE THIS MORNING TO HIGH END OF CHANCE... AND MAINTAIN HIGH CHANCE IN FAR E THIS AFTERNOON...WITH LESSER MAXIMUM N BLUE RIDE. DEW POINTS RUNNING HIGH I-77 CORRIDOR...AND UPDATED WITH LATEST OBSERVATIONS AND GFS. BEST QPF EXPECTED I-77 AND N BLUE RIDGE ESCARPMENT...FFG SHOWING SC ESCARPMENT MOST VULNERABLE TO FLOODING. UPDATED WIND WITH LATEST RUC...THOUGH LITTLE CHANGE. TEMPERATURES GENERALLY RUNNING CLOSE TO 06Z MAV GUIDANCE...AND WILL ONLY ADJUST HOURLY TREND...NOT FORECAST MAXIMUMS. SKY FORECAST APPEARS ON TRACK. WILL UPDATE ZONES CLOSE TO 11 AM TO CAPTURE AFTERNOON WORDING. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 337 AM EDT MON AUG 2 2004 SHORT TERM (TODAY THROUGH TUESDAY)... SATELLITE CURRENTLY SHOWING WIDESPREAD LOW CLOUDS SPREADING ACROSS THE FA FROM N TO S. WITHIN THE DEVELOPING CLOUD COVER RADAR IS SHOWING NUMEROUS SMALL SHOWERS AND ISO TS DEVELOPING OVER THE NC PIEDMONT AND EASTERN FOOTHILLS. THESE SHOWERS ARE DEVELOPING NEAR THE POPULAR PLACEMENT OF THE HARD TO FIND STATIONARY FRONT. I WILL WORK WITH THE GFS FOR FORECAST DETAILS FOR TODAY AND TONIGHT TO COVER T.S. ALEX. SHOWERS AND THUNDERSTORM DEVELOPMENT SHOULD CONTINUE THROUGH THE DAY AS H5 TROF AXIS APPROACHES FROM THE WEST. BANDS OF SH/TS FROM THE CYCLONE SHOULD PRODUCE THE BEST COVERAGE ALONG AND EAST OF THE I-77 CORRIDOR BY THIS AFTERNOON. FURTHER WEST...COVERAGE SHOULD TAPER OFF AS FRONTAL BOUNDARY MAY SPLIT THE FORECAST AREA IN HALF AND WILL LIMIT AVAILABLE MOISTURE/INSTABILITY WEST. NEVERTHELESS...I WILL PAINT A SECONDARY MAXIMA IN POPS OVER THE EAST FACING SLOPES OF THE NC MTNS AND ADJACENT FOOTHILLS TO HIGHLIGHT POSSIBLE UPSLOPE FLOW. AFTER 1Z TUE...WILL RAPIDLY DECREASE POPS AS SH/TS STRUGGLE TO SURVIVE AS THE SUBSISTENCE BAND FROM DEEPENING CYCLONE MOVES EAST...LOSS OF HEATING... AND BETTER DOWNSLOPE. ATMOS WILL DRY FURTHER TUE AND DEEP RIDGING WILL BUILD FROM THE WEST. THIS WILL LEAD TO A TYPICAL EARLY AUGUST DAY IN THE SE WITH HIGHS REACHING THE UPPER 80S TO L90S. BY THIS TIME...T.S. ALEX SHOULD BE OVER THE COASTAL WATERS OF NC AND WILL HAVE LITTLE IMPACT ON THE FORECAST. WILL SWITCH MODEL PREFERENCE TO THE ETA FOR THE REST OF THE PACKAGE AS GFS ARTIFICIALLY PUMPS UP THE NEXT SYSTEM DUE TO THE MODEL/S CONVECTIVE SCHEME. ETA FORECAST SOUNDINGS FOR TUE AFTERNOON DEPICT A STRONG SUBSTANCE INVERSION AROUND 650MB. CURRENT FORECAST TEMPS AND DWPTS WOULD CARRY PARCEL PAST THE INVERSION LEVEL...SUPPORTING DEEP CONVECTION IF A TRIGGER EXIST. HOWEVER...THERE IS A LACK OF A DEFINABLE TRIGGER AND MOS GUIDANCE SHOWS RATHER LOW CHCS. I WILL LIMIT TUE POPS TO RIDGETOP CHCS IN THE LATE AFTERNOON AND EARLY EVENING...MAY NOT MAKE IT INTO THE TEXT HOWEVER. LONG TERM (TUESDAY NIGHT THROUGH SUNDAY)... WED...SOUTH BOUND COLD FRONT APPROACHES FROM THE GREAT LAKES WHILE FA REMAINS UNDER DEEP RIDGING. TEMPS SHOULD RISE OVER TUES VALUES...HOWEVER...MAV GUIDANCE SEEMS A LITTLE TOO HOT. BY 0Z WED...THE FRONT IS EXPECTED TO PARALLEL THE OHIO RIVER VALLEY...AND POSSIBLY SINKING TO NC BY 12 THU. PATTERN SHOULD YIELD AN MCS TO TRACK ALONG THE FRONT...WHICH ACCORDING TO THE ETA WOULD ARRIVE OVER THE LOWER APPALACHIANS WED NIGHT AND THU AM. I WILL INCREASE POPS...ESPECIALLY OVER THE MTNS DURING THE PERIOD. THE FA SHOULD REMAIN UNDER A LONGWAVE TROF AXIS THROUGH THE REST OF THE WEEK AND INTO THE WEEKEND...WILL MAKE LITTLE CHANGE BEYOND THU. AVIATION... EXPECT MVFR CIGS ALL TAF SITES THROUGH SUNRISE...THEN VFR BY MID MORNING. KAVL AND KCLT WILL SEE MVFR VIS IN FOG...THEN AT LEAST TEMPO IFR AT KAVL DUE TO LOCAL RAIN YESTERDAY. WITH LOW LEVELS VERY MOIST EXPECT AT LEAST SCT CONVECTION THIS AFTN-EVE DUE TO SFC HEATING...UPPER JET ENHANCEMENT AND CONTINUED MOIST E FLOW FROM ALEX. HAVE INCLUDED CB CLOUDS AND VCTS AT ALL SITES 19-20Z ON. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SHORT TERM (UPDATE)...JAT sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 940 PM EDT MON AUG 2 2004 SHWRS WIDESPRD ACROSS FA ATTM WITH ONLY SCT THUNDER RPTD. ALEX NOW ACCELERATING NE ALONG CAROLINA COAST AS UPR LVL WNDS BEGIN TO PICK IT UP. RAIN BANDS CONT TO MOV N AS STORM DOES...THUS HAVE UPDATED ZONES TO INCRS POPS ACROSS THE BOARD. CAT POPS ACROSS SERN ZONES... LIKELY ELSEWHERE DUE TO LINGERING TROFFINESS. WNDS GNRLY LGT ACROSS FA...BUT SHUD BEGIN TO INCRS BY SR ACROSS SERN ZONES. NO CHANGES TO ANY WATCHES/WRNGS THIS EVE. FCSTID = 44 HAVE SENT ZONES AFTER WAITING FOR COORDINATION W/ NHC FOR UPDATED TROPICAL STORM WRNGS. NOW HAVE NC ZONES ALONG COAST AND ALBEMARLE SND IN TROPICAL STORM WARNING. (GATES/HERTFORD/NORTHAMPTON NC ARE NOT IN TROP STM WRNG). TS ALEX TRENDING A BIT TO THE LEFT (WEST) OF EARLIER FCSTS...KEEPING IT CLOSER TO COAST. IS ALSO MOVING QUITE SLOW (OVER WARM WATERS OF GULF STRM) WHICH HAS ALLOWED FAIRLY SIGNIFICANT STRENTHENING AND ORGANIZATION TODAY. HAVE WINDS CAPPED AT GUSTS TO 45 MPH FOR COASTAL CURRITUCK AND 40 MPH OTHER NC CNTYS IN THE WRNG. FOR DETAILS SEE LATEST TPC FCSTS. ______________PREV AFD BELOW_____________ .SYNOPSIS...TROPICAL STORM ALEX...LOCATED OFF THE SOUTH CAROLINA COAST...WILL MOVE SLOWLY NORTHEAST ALONG THE CAROLINA COASTLINE THROUGH TUESDAY NIGHT. OTHERWISE A STATIONARY FRONT NEAR THE MOUNTAINS WILL GRADUALLY DISSIPATE. WEAK HIGH PRESSURE WILL BUILD OVER THE WESTERN PORTIONS OF THE AREA LATE TUESDAY AFTERNOON INTO WEDNESDAY...AS THE STORMS MOVES OFF TO THE EAST. A COLD FRONT PASSES THROUGH THURSDAY. RELATIVELY COOL HIGH PRESSURE BUILDS INTO THE MID ATLC FOR THE UPCOMING WEEKEND. && .SHORT TERM...A BIG MESS ACROSS THE REGION. SEVERAL FLS STATEMENTS HAVE BEEN ISSUED FOR URBAN/SMALL STRM FLOODING THIS AFTN...AND FFW EARLIER FOR NORFOLK...W/ POTENTIAL FOR A LOT MORE RAIN ON THE WAY. PREC WTRS HAVE GNRLY BEEN ARND 2.5 INCHES ACRS SE 1/2 CWA TODAY...W/ DEW PTS AGAIN IN MID TO UPR 70S. HAVE ISSUED FFA (FLOOD WATCH) FOR AREAS GNRLY E OF I-95 IN OUR VA/NC ZONES. LEFT METRO RIC...PIEDMONT AND MD ZONES OUT. (SEE FFAAKQ FOR DETAILS). DECIDED TO DO THIS BASED ON RUC LOW LVL CONV PATTERN WHICH HAS VERIFIED A BIT BETTER THAN GFS OR ETA TODAY. AS FOR TROP STM ALEX...CURRENT LOCATION IS ABOUT 110 MILES SE OF CHARLESTON SC...AND STORM IS STARTING TO MOVE TO NE OVR PAST FEW HRS. MAX SUST WINDS ARE NOW ARND 60 MPH. BIG THREAT IN SHORT TERM WILL CONTINUE TO BE FROM THIS STORM. AS OF RIGHT NOW TROP STM WRNGS/WATCHES REMAIN S OF AKQ CWA. ANY CHANGES TO THIS WILL BE UPDATED LATER THIS EVENG. TRENDED WETTER ON TUE FOR ERN ZONES AS TS ALEX PROGGED TO MOVE SLOWER...WED STILL LOOKS QUITE WARM W/ ONLY SCHC OR LOWER FOR POPS BEHIND DEPATING SYSTEM W/ GOOD SUBSIDENCE. && .LONG TERM...THU THROUGH NEXT MON...MODELS CONTINUE TO ADVERTISE A BIG AIRMASS CHANGE BY FRI INTO THE WEEKEND. STRONG COLD FRONT (FOR SUMMER) ON THU AS A DEEP ERN CONUS TROF TAKES CONTROL BY FRI. MEX NUMBERS ARE REPRESENTATIVE OF DEEPEST GFS SOLN WHILE UKMET/ECMWF/CANADIAN ARE NOT QUITE AS STRONG W/ THE TROF. HAVE THEREFORE STAYED A FEW DGRS ABOVE MEX GDNC...WHICH IS STILL ABOUT 10 F BELOW NORMAL FOR EARLY AUGUST. THINK SOME CLOUDS WILL STAY ARND THU/FRI/SAT THEN MSUNNY SUN/MON AS VORT MAX SLIDES N A ND E OF AREA. HAVE CHC POPS THU W/ GOOD LOW LVL JET ENERGY/CONV W/ FRONT...THEN W/ SCHC POPS OR LOWER FRI THROUGH MON IN DRIER AMS. && .AVIATION...AREAS OF MVFR/IFR IN HEVIER TSRA...W/ OTHERS GNRLY SEEING VFR. FOR NEXT 24 HRS PIEDMONT SITES WILL BE MAINLY VFR W/ PATCHY AREAS OF MVFR...CLOSER TO COAST EXPECT MORE WIDESPRD MVFR/IFR. NE WINDS WILL BE ON INCREASE ON TUE ACRS SE SECTIONS. && .MARINE...SCA FOR CSTL WTRS S OF PARRAMORE...CHES BAY S OF NEW PT COMFORT...AND CURRITUCK SND. AND HAVE SCA EXPECTED FOR REMAINDER OF CSTL WTRS AS WELL ON TUE AS TROP STM SWELLS BEGIN TO FURTHER AFFECT THE AREA W/ STORM TRACKING A BIT CLOSER TO REGION. && .FIRE WEATHER...WET AND BREEZY ESPECIALLY ERN HALF OF CWA. && .HYDROLOGY...SEBRELL STILL IN MINOR FLOOD. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. VA...FFA FOR VAZ072-073-078-081>100 NC...FFA FOR NCZ012>017-030>032-102. TRPLCL STORM WRNG NC015>017- 030>032-102 MARINE...TRPLCL STORM WRNG CSTL WTRS S OF VA/NC BRDR & CURRITUCK SND. SCA FOR CSTL FROM PARRAMORE ISL TO NC/VA BRDR...CHES BAY S OF NEW PT COMFORT. $$ va AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE WAKEFIELD VA 506 PM EDT MON AUG 2 2004 HAVE SENT ZONES AFTER WAITING FOR COORDINATION W/ NHC FOR UPDATED TROPICAL STORM WRNGS. NOW HAVE NC ZONES ALONG COAST AND ALBEMARLE SND IN TROPICAL STORM WARNING. (GATES/HERTFORD/NORTHAMPTON NC ARE NOT IN TROP STM WRNG). TS ALEX TRENDING A BIT TO THE LEFT (WEST) OF EARLIER FCSTS...KEEPING IT CLOSER TO COAST. IS ALSO MOVING QUITE SLOW (OVER WARM WATERS OF GULF STRM) WHICH HAS ALLOWED FAIRLY SIGNIFICANT STRENTHENING AND ORGANIZATION TODAY. HAVE WINDS CAPPED AT GUSTS TO 45 MPH FOR COASTAL CURRITUCK AND 40 MPH OTHER NC CNTYS IN THE WRNG. FOR DETAILS SEE LATEST TPC FCSTS. ______________PREV AFD BELOW_____________ .SYNOPSIS...TROPICAL STORM ALEX...LOCATED OFF THE SOUTH CAROLINA COAST...WILL MOVE SLOWLY NORTHEAST ALONG THE CAROLINA COASTLINE THROUGH TUESDAY NIGHT. OTHERWISE A STATIONARY FRONT NEAR THE MOUNTAINS WILL GRADUALLY DISSIPATE. WEAK HIGH PRESSURE WILL BUILD OVER THE WESTERN PORTIONS OF THE AREA LATE TUESDAY AFTERNOON INTO WEDNESDAY...AS THE STORMS MOVES OFF TO THE EAST. A COLD FRONT PASSES THROUGH THURSDAY. RELATIVELY COOL HIGH PRESSURE BUILDS INTO THE MID ATLC FOR THE UPCOMING WEEKEND. && .SHORT TERM...A BIG MESS ACROSS THE REGION. SEVERAL FLS STATEMENTS HAVE BEEN ISSUED FOR URBAN/SMALL STRM FLOODING THIS AFTN...AND FFW EARLIER FOR NORFOLK...W/ POTENTIAL FOR A LOT MORE RAIN ON THE WAY. PREC WTRS HAVE GNRLY BEEN ARND 2.5 INCHES ACRS SE 1/2 CWA TODAY...W/ DEW PTS AGAIN IN MID TO UPR 70S. HAVE ISSUED FFA (FLOOD WATCH) FOR AREAS GNRLY E OF I-95 IN OUR VA/NC ZONES. LEFT METRO RIC...PIEDMONT AND MD ZONES OUT. (SEE FFAAKQ FOR DETAILS). DECIDED TO DO THIS BASED ON RUC LOW LVL CONV PATTERN WHICH HAS VERIFIED A BIT BETTER THAN GFS OR ETA TODAY. AS FOR TROP STM ALEX...CURRENT LOCATION IS ABOUT 110 MILES SE OF CHARLESTON SC...AND STORM IS STARTING TO MOVE TO NE OVR PAST FEW HRS. MAX SUST WINDS ARE NOW ARND 60 MPH. BIG THREAT IN SHORT TERM WILL CONTINUE TO BE FROM THIS STORM. AS OF RIGHT NOW TROP STM WRNGS/WATCHES REMAIN S OF AKQ CWA. ANY CHANGES TO THIS WILL BE UPDATED LATER THIS EVENG. TRENDED WETTER ON TUE FOR ERN ZONES AS TS ALEX PROGGED TO MOVE SLOWER...WED STILL LOOKS QUITE WARM W/ ONLY SCHC OR LOWER FOR POPS BEHIND DEPATING SYSTEM W/ GOOD SUBSIDENCE. && .LONG TERM...THU THROUGH NEXT MON...MODELS CONTINUE TO ADVERTISE A BIG AIRMASS CHANGE BY FRI INTO THE WEEKEND. STRONG COLD FRONT (FOR SUMMER) ON THU AS A DEEP ERN CONUS TROF TAKES CONTROL BY FRI. MEX NUMBERS ARE REPRESENTATIVE OF DEEPEST GFS SOLN WHILE UKMET/ECMWF/CANADIAN ARE NOT QUITE AS STRONG W/ THE TROF. HAVE THEREFORE STAYED A FEW DGRS ABOVE MEX GDNC...WHICH IS STILL ABOUT 10 F BELOW NORMAL FOR EARLY AUGUST. THINK SOME CLOUDS WILL STAY ARND THU/FRI/SAT THEN MSUNNY SUN/MON AS VORT MAX SLIDES N A ND E OF AREA. HAVE CHC POPS THU W/ GOOD LOW LVL JET ENERGY/CONV W/ FRONT...THEN W/ SCHC POPS OR LOWER FRI THROUGH MON IN DRIER AMS. && .AVIATION...AREAS OF MVFR/IFR IN HEVIER TSRA...W/ OTHERS GNRLY SEEING VFR. FOR NEXT 24 HRS PIEDMONT SITES WILL BE MAINLY VFR W/ PATCHY AREAS OF MVFR...CLOSER TO COAST EXPECT MORE WIDESPRD MVFR/IFR. NE WINDS WILL BE ON INCREASE ON TUE ACRS SE SECTIONS. && .MARINE...SCA FOR CSTL WTRS S OF PARRAMORE...CHES BAY S OF NEW PT COMFORT...AND CURRITUCK SND. AND HAVE SCA EXPECTED FOR REMAINDER OF CSTL WTRS AS WELL ON TUE AS TROP STM SWELLS BEGIN TO FURTHER AFFECT THE AREA W/ STORM TRACKING A BIT CLOSER TO REGION. && .FIRE WEATHER...WET AND BREEZY ESPECIALLY ERN HALF OF CWA. && .HYDROLOGY...SEBRELL STILL IN MINOR FLOOD. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. VA...FFA FOR VAZ072-073-078-081>100 NC...FFA FOR NCZ012>017-030>032-102. TRPLCL STORM WRNG NC015>017- 030>032-102 MARINE...TRPLCL STORM WRNG CSTL WTRS S OF VA/NC BRDR & CURRITUCK SND. SCA FOR CSTL FROM PARRAMORE ISL TO NC/VA BRDR...CHES BAY S OF NEW PT COMFORT. && .PRELIMINARY POINT TEMPS/POPS... SBY 71 85 70 90 / 60 50 20 10 OXB 70 83 71 87 / 60 50 20 10 WAL 73 82 71 89 / 60 50 20 10 FVX 71 88 70 92 / 50 30 10 20 RIC 72 86 72 92 / 60 40 10 10 PTB 72 88 70 94 / 60 40 10 10 AKQ 72 84 71 92 / 60 50 10 10 PHF 73 84 72 92 / 70 50 20 10 ORF 74 83 74 91 / 70 60 20 10 ECG 75 81 72 90 / 70 70 20 10 && $$ BROWN va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 415 PM EDT MON AUG 2 2004 .SYNOPSIS...TROPICAL STORM ALEX...LOCATED OFF THE SOUTH CAROLINA COAST...WILL MOVE SLOWLY NORTHEAST ALONG THE CAROLINA COASTLINE THROUGH TUESDAY NIGHT. OTHERWISE A STATIONARY FRONT NEAR THE MOUNTAINS WILL GRADUALLY DISSIPATE. WEAK HIGH PRESSURE WILL BUILD OVER THE WESTERN PORTIONS OF THE AREA LATE TUESDAY AFTERNOON INTO WEDNESDAY...AS THE STORMS MOVES OFF TO THE EAST. A COLD FRONT PASSES THROUGH THURSDAY. RELATIVELY COOL HIGH PRESSURE BUILDS INTO THE MID ATLC FOR THE UPCOMING WEEKEND. && .SHORT TERM...A BIG MESS ACROSS THE REGION. SEVERAL FLS STATEMENTS HAVE BEEN ISSUED FOR URBAN/SMALL STRM FLOODING THIS AFTN...AND FFW EARLIER FOR NORFOLK...W/ POTENTIAL FOR A LOT MORE RAIN ON THE WAY. PREC WTRS HAVE GNRLY BEEN ARND 2.5 INCHES ACRS SE 1/2 CWA TODAY...W/ DEW PTS AGAIN IN MID TO UPR 70S. HAVE ISSUED FFA (FLOOD WATCH) FOR AREAS GNRLY E OF I-95 IN OUR VA/NC ZONES. LEFT METRO RIC...PIEDMONT AND MD ZONES OUT. (SEE FFAAKQ FOR DETAILS). DECIDED TO DO THIS BASED ON RUC LOW LVL CONV PATTERN WHICH HAS VERIFIED A BIT BETTER THAN GFS OR ETA TODAY. AS FOR TROP STM ALEX...CURRENT LOCATION IS ABOUT 110 MILES SE OF CHARLESTON SC...AND STORM IS STARTING TO MOVE TO NE OVR PAST FEW HRS. MAX SUST WINDS ARE NOW ARND 60 MPH. BIG THREAT IN SHORT TERM WILL CONTINUE TO BE FROM THIS STORM. AS OF RIGHT NOW TROP STM WRNGS/WATCHES REMAIN S OF AKQ CWA. ANY CHANGES TO THIS WILL BE UPDATED LATER THIS EVENG. TRENDED WETTER ON TUE FOR ERN ZONES AS TS ALEX PROGGED TO MOVE SLOWER...WED STILL LOOKS QUITE WARM W/ ONLY SCHC OR LOWER FOR POPS BEHIND DEPATING SYSTEM W/ GOOD SUBSIDENCE. && .LONG TERM...THU THROUGH NEXT MON...MODELS CONTINUE TO ADVERTISE A BIG AIRMASS CHANGE BY FRI INTO THE WEEKEND. STRONG COLD FRONT (FOR SUMMER) ON THU AS A DEEP ERN CONUS TROF TAKES CONTROL BY FRI. MEX NUMBERS ARE REPRESENTATIVE OF DEEPEST GFS SOLN WHILE UKMET/ECMWF/CANADIAN ARE NOT QUITE AS STRONG W/ THE TROF. HAVE THEREFORE STAYED A FEW DGRS ABOVE MEX GDNC...WHICH IS STILL ABOUT 10 F BELOW NORMAL FOR EARLY AUGUST. THINK SOME CLOUDS WILL STAY ARND THU/FRI/SAT THEN MSUNNY SUN/MON AS VORT MAX SLIDES N A ND E OF AREA. HAVE CHC POPS THU W/ GOOD LOW LVL JET ENERGY/CONV W/ FRONT...THEN W/ SCHC POPS OR LOWER FRI THROUGH MON IN DRIER AMS. && .AVIATION...AREAS OF MVFR/IFR IN HEVIER TSRA...W/ OTHERS GNRLY SEEING VFR. FOR NEXT 24 HRS PIEDMONT SITES WILL BE MAINLY VFR W/ PATCHY AREAS OF MVFR...CLOSER TO COAST EXPECT MORE WIDESPRD MVFR/IFR. NE WINDS WILL BE ON INCREASE ON TUE ACRS SE SECTIONS. && .MARINE...SCA FOR CSTL WTRS S OF PARRAMORE...CHES BAY S OF NEW PT COMFORT...AND CURRITUCK SND. AND HAVE SCA EXPECTED FOR REMAINDER OF CSTL WTRS AS WELL ON TUE AS TROP STM SWELLS BEGIN TO FURTHER AFFECT THE AREA W/ STORM TRACKING A BIT CLOSER TO REGION. && .FIRE WEATHER...WET AND BREEZY ESPECIALLY ERN HALF OF CWA. && .HYDROLOGY...SEBRELL STILL IN MINOR FLOOD. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. VA...FFA FOR VAZ072-073-078-081>100 NC...FFA FOR NCZ012>017-030>032-102. MARINE...SCA FOR CSTL FROM PARRAMORE ISL TO CURRITUCK BCH LGT...CHES BAY S OF NEW PT COMFORT...AND CURRITUCK SND. && .PRELIMINARY POINT TEMPS/POPS... SBY 71 85 70 90 / 60 50 20 10 OXB 70 83 71 87 / 60 50 20 10 WAL 73 82 71 89 / 60 50 20 10 FVX 71 88 70 92 / 50 30 10 20 RIC 72 86 72 92 / 60 40 10 10 PTB 72 88 70 94 / 60 40 10 10 AKQ 72 84 71 92 / 60 50 10 10 PHF 73 84 72 92 / 70 50 20 10 ORF 74 83 74 91 / 70 60 20 10 ECG 75 81 72 90 / 70 70 20 10 && $$ BROWN va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1215 PM EDT MON AUG 2 2004 UPDATED ZONES (AWHILE AGO) TO INCREASE POPS TO CAT IN NC/HI LKLY SE VA W/ GOOD LOW LVL (1000 TO 950 MB) CONV SEEN ON RUC. RETAINED HVY RAIN WORDING IN ZONES AS PREC WTRS ARE NEAR 2.5 INCHES...HAVE ALREADY ISSUED FFW FOR ORF/PORTSMOUTH...AND WILL CONTINUE TO MONITOR STORMS CLOSELY FOR TORRENTIAL RAINS AND FLOODING. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. VA...NONE. NC...NONE. MARINE...NONE. && BROWN && _____________PREV AFD BLO___________ .SYNOPSIS... STNRY FNTL BNDRY XTNDG FM CNTRL NEW ENG TO TN GRDLY DSPTS DURG THE NEXT 24-36 HRS...WHL LO PRES GIVES GLANCING SHOT AT THE SE CONUS CST. WK HI PRES TAKES HOLD TUE AFTN INTO WED...FOLLOWED BY THE NEXT CDFNT APPROACHING THE RGN WED NGT...PUSHING OFFSHR THU. UNSEASONABLY STRNG TROF ALOFT DVLPS OVR ERN STATES BY THE WKND. && .SHORT TERM... LINGERING CNVTN GENLY W OF RIC ATTM...WL START THE FCST (THIS MORNING) W/ LOEST POPS SE SXNS OF VA/NE NC...HIEST W OF RIC. WL BE LLVL BNDRYS GALORE ACRS THE FA TDA...SO HARD TO PINPOINT WHR GREATEST THREAT FOR PCPN WOULD BE TDY. ENUF IS ENUF WRT RA...BUT APRS THAT CONTD HIER THAN CLIMO CHCS AGAIN TDA INTO TNGT. LCLLY HVY RA FM TSRAS INTO TNGT...GIVEN PERSISTENT PWS AOA 2" ACRS FA. LTL IF ANY SGNFT EFFECTS FM LO BRUSHING CST TDA THRU TUE. MDLS SUGG THAT DEEP MSTR AXIS SLIPS OFFSHR BY TUE AFTN...LEADING TO DCRSG POPS HEADING INTO MIDWEEK. && .LONG TERM... LIKELY TO BE AN END TO OPPRESSIVE HUMIDITY BY THE END THE WK/WKND AS STRNG TROF ALOFT FORMS OVR SE CANADA AND XTNDS SWD THRU ERN STATES. XTNDD TEMPS (FRI THRU SUN) WL LIKELY NEED TO BE ADJSTD DN...AND WL LET DAYSHIFT HANDLE THAT AFT COORD. && .AVIATION... LO CIGS FOR A WHL THIS MORNING...THEN IFR/MVFR IN TSRAS (MNLY THIS AFTN INTO TNGT). && .MARINE... MRGNL INCRS IN SEAS (TO 5 TO 6 FT) XPCTD FM S TO N ALG CSTL WTRS LT TNGT THRU TUE...WHL WND SPDS RMN BLO SCA. && .HYDROLOGY... SEBRELL CONTS TO BE JUST ABV FLD STAGE...FCST TO FALL BLO LTR TDA/TNGT. WL HV TO MONITOR OTR LCTNS FOR RISES GIVEN RECENT RA (AND PSBL ADDTNL HVY RA NEXT 12-24 HRS). && $$ 25/32 va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1020 AM EDT MON AUG 2 2004 .SHORT TERM (REST OF TODAY)... SHRTWV HELPING MORNING PCPN WL REMAIN OVR CWA TDY BUT MOVE EAST BY TUES MORN. RUC HAS BEST LIS IN THE WRN CWA AND THERE IS MORE BREAKS IN THE CLOUD COVER THERE SO SCT TSRA IS EXPECTED. AND ETA SHOWING SOME UPPER DIVERGANCE AND SFC/8H CONVERGENCE AT LEAST THRU 00Z THROUGH THIS EVENING. WL KEEP SCT POPS ACRS CWA. ONLY MINOR CHANGES TO MAX TEMPS BASED ON LATEST LAMP GUID AND CURRENT OBS. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 720 AM COVERAGE OF SHOWERS/TSTMS ACROSS THE REGION THIS MORNING WILL NOT DECREASE...THEREFORE AM UPDATING TO INCREASE POPS ACROSS THE REGION EARLY THIS MORNING. NO OTHER CHANGES. SHORT TERM (TODAY THROUGH WEDNESDAY)... JET INDUCED PCPN ALONG WEAK FRONTAL/DEFORMATION ZONE WILL CONT ACROSS MUCH OF THE FA THRU THE DAY...PULLING OUT TO THE EAST LATE. HIGH 850 THETA-E VALUES ALONG WITH MUCH HIGHER THAN NORMAL PCPL WATER WILL RESULT IN VERY HEAVY RAINS ACROSS THE SOUTHERN 2/3RDS OF THE FCST AREA. A FLOOD WATCH MIGHT BE CONSIDERED LATER THIS MORNING...DEPENDING ON RADAR TRENDS FOR THE NEXT FEW HOURS...WHERE 06Z MODEL RUNS PLACE THE AXIS OF HEAVIEST RAIN TODAY...AND HOW WELL THEY ARE IN AGREEMENT. JET PULLS EAST TONIGHT AS TS ALEX MOVES UP THE CAROLINA COAST. DRY AIR PUSHES INTO THE WEST AND SHORTWAVE RIDGING TAKES CONTROL OF THE AREA THRU TUE NGT. WE SEE GRADUALLY LOWERING HEIGHTS OVER SOUTHEAST CANADA AND THE EASTERN U.S. TUE NGT AND WED WITH S/WV ENERGY SLIDING IN MIDWEEK. HOWEVER MODELS ARE HAVING SOME TROUBLE WITH THE TIMING OF THIS ENERGY AND SO CONFIDENCE IN MIDWEEK RAIN CHANCE IS LOW. LONG TERM (WED NIGHT THROUGH SUNDAY)... HOWEVER...CONFIDENCE IS HIGHER THAT A DEEP TROF WILL DEVELOP OVER THE EASTERN HALF OF THE COUNTRY BY THE END OF THE WEEK. AT THIS TIME MODELS KEEP PCPN DEVELOPMENT JUST EAST OF THE FA...RESULTING IN A MAINLY DRY...COOL FCST FOR THE REGION FRIDAY THRU SUNDAY. .AVIATION... WILL ADD MORE CONVECTION TO THE TAFS THIS MORNING AS LOOKS LIKE SUBSIDENCE ZONE WILL NOT MATERIALIZE OVER THIS AREA. VFR CONDS DEVELOPING BY MIDDAY MOST PLACES OUTSIDE OF NUMEROUS SHOWERS AND ISOLATED TSTMS. LEAST COVERAGE OF TSTMS AT BLF AND LWB. AXIS OF CONVERGENCE AND JET ENHANCED LIFT WILL PULL OUT TO THE EAST THIS EVENING. EXPECT SOME IFR/LIFR VSBYS IN THE MTNS LATE. && .RNK WATCHES/WARNINGS/ADVISORIES... NC...NONE. VA...NONE. WV...NONE. && $$ SHORT TERM (UPDATE)...AMS va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 715 AM CDT MON AUG 2 2004 .UPDATE...LARGE BOW ECHO MOVG ESE FM MN AT 40 KTS. IT HAS UNDERGONE 3 STRENGTHENING AND WEAKENING CYCLES...AND GROWN IN SIZE WITH EACH. STABLE BOUNDARY LAYER APPEARED TO HAVE GREATLY LIMITED STRENGTH OF THE CONVECTIVE GUSTS THAT REACHED THE SFC OVERNIGHT. QUESTION WL BE HOW THE SYSTEM EVOLVES DURING THE NEXT FEW HRS. THE BOUNDARY LAYER OVER THE FCST AREA WAS EVEN MORE STABLE THAN BACK OVER MN...BUT MORNING SUNSHINE WL LIKELY CAUSE A RAPID DESTABILIZATION. IF TSTM COMPLEX CAN HOLD TOGETHER ANOTHER FEW HRS...THERE IS THE POSSIBILITY THAT IT COULD INTENSIFY SIGNIFICANTLY DURING THE LATE MORNING HRS. IF THAT OCCURS...WIDESPREAD DAMAGING WINDS WL BE POSSIBLE ACRS THE SW PART OF THE FCST AREA DURING THE LATE MORNING AND POSSIBLY INTO THE EARLY AFTERNOON. THE ESEWD MVMT HAS BEEN VERY CONSISTENT AT 40 KTS...AND THAT WOULD TAKE IT INTO WRN MARATHON COUNTY ARND 10 AM. ALSO BEEN WATCHING NNE/SSW LINE OF TSTMS DEVELOP NE FM IA. SHEAR WAS MUCH WEAKER THERE...AND THOSE STORMS WERE MOVG MORE SLOWLY TO THE E... AND PROBABLY PRODUCING SOME VERY HVY RAIN. BEST GUESS WAS THAT THAT AREA OF STORMS WOULD REMAIN S OF THE FCST AREA. 4 AM FCST STILL HOLDING UP WELL...SO NO SIG CHANGES NEEDED FOR NOW. .PREV DISCUSSION...THE DISCUSSION FROM THE 4 AM FORECAST PACKAGE FOLLOWS. .SYNOPSIS...MAJOR AMPLIFICATION OF THE UPR PATTERN EXPECTED TO OCCUR DURING THIS FCST CYCLE. THIS WL CAUSE THE WARM HUMID AIR ACRS THE FCST AREA TO BE REPLACED BY COOLER AND MUCH DRIER CANADIAN AIR. MAIN CHC OF PCPN WL COME EARLY WHILE THE MOISTURE IS IN PLACE ACRS THE AREA. TEMPS WL START OUT WARM AND THEN DROP TO A BIT BLO NORMAL LEVELS. .SHORT TERM...TDA/TNGT/TUE. FOCUS IS ON SVR THREAT. MODELS STILL STRUGGLING WITH THE DETAILS OF THE PATTERN...AS BOTH THE ETA AND RUC FCST SUBSIDENCE AND DRY WX ACRS ERN SD AT THE SAME TIME AN INTENSE CONVECTIVE SYSTEM GENERATED A MEASURED A 78KT GUST. THAT CONVECTIVE SYSTEM WAS WEAKENING AND HEADING SSEWD TOWARD OMA. AS THAT WAS OCCURRING...SEVERAL CLUSTERS OF TSTMS WERE SLOWLY DEVELOPING ACRS ND... AND THE LEAD CLUSTER COMING OUT OF THAT AREA REALLY INTENSIFIED BTWN 230 AND 330 AM. GIVEN THE UPR SHRTWV SUPPORTING THOSE STORMS AND THE FRONTAL BOUNDARY SETTLING SWD INTO THE AREA...EXPECT THOSE STORMS TO EXPAND/INTENSIFY AND HEAD SE THIS MORNING. THEY ARE ALREADY HEADED INTO SOME SFC BASED INSTABILITY EARLY THIS MORNING...AND MOSTLY CLR SKIES DOWNSTREAM SHOULD ALLOW THE ATM AHEAD OF THOSE STORMS TO DESTABILIZE EVEN MORE AFTER SUN-UP. THERE WAS ALSO SOME DEVELOPMENT ACRS WRN UPPER MICHIGAN...AND THOSE STORMS MAY TEND TO BUILD WWD AND LINK UP WITH THE WRN STORMS DURING THE MORNING. EXPECT THAT THIS DEVLEOPING MCS WL BE THE MAIN SVR THREAT FOR THE FCST AREA...WITH THE CURRENT TRACK OF THE STORMS PLACING THE SW PORTION OF THE FCST AREA AT THE GREATEST RISK. ASSUMING THAT CONVECTIVE SYSTEM COMES ACRS THE FCST AREA MID-DAY...DON/T THINK THE ATM WL HAVE A CHANCE TO RELOAD TO SUPPORT ANOTHER ROUND OF SIG CONVECTION. CARRIED CHC POPS INTO THE EVENING AS SCT STORMS POSSIBLE... THEN MAINTAINED PREV FCST/S IDEA OF DRY WX AFTER THAT. THE ETA AND GFS SHOWED LINGERING HIGH DWPTS AND CONSIDERABLE INSTABILITY INTO TUE AFTN...BUT WITH THE UPR FLOW STARTING TO VEER MORE NWLY AND LOW-LEVEL N/NELY FLOW IT WOULD SEEM LIKELY THAT MAIN CONVECTION WOULD FOCUS SW OF THE AREA. MID-LVL LAPSE RATES ALSO PROGGED TO BE MUCH MORE STABLE BY TUE. .LONG TERM...TUESDAY NIGHT THROUGH SUNDAY. MEDIUM RANGE MODELS SHOW VERY GOOD AGREEMENT AT 500MB THROUGH THE END OF THE WEEK. POLAR VORTEX OVER HUDSON BAY DROPS SOUTH AND UPPER FLOW VEERS TO NORTHWEST BY MIDWEEK. THIS ALLOWS SURFACE HIGH TO SETTLE SOUTH ACROSS THE GREAT LAKES AND PRODUCE DRY COOL WEATHER FOR THE MIDDLE AND END OF THE WEEK. THE BIG QUESTION FOR THIS PART OF THE FORECAST IS WHETHER THERE WILL BE ANY SHOWERS OR THUNDERSTORMS TUESDAY NIGHT. THE ETA SUGGESTS THAT THE FRONT WILL BE FAR ENOUGH SOUTH TO KEEP IT DRY HERE. GFS HAS MORE OF A WAVE ALONG FRONT AND WOULD FAVOR A CHANCE OF PRECIPITATION. WILL KEEP IT DRY FOR NOW AS THE ETA HAS DONE BETTER WITH LOW LEVEL DRY AIR ARRIVING FROM THE NORTHEAST IN THESE EVENTS THIS YEAR. NCEP ALSO PREFERS THE ETA. .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SKOWRONSKI/RDM WWW.CRH.NOAA.GOV/GRB wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 153 AM MDT TUE AUG 3 2004 .DISCUSSION...COLD FRONT CONTINUES TO MOVE ACROSS CENTRAL NEBRASKA EARLY THIS MORNING. PRESSURE RISES BEHIND FRONT ARE NOT IMPRESSIVE...SO HAVE DISCARDED THE FASTER GFS FOR SURFACE FEATURES. WILL USE THE RUC FOR THE VERY SHORT TERM. THIS WILL ALLOW ENOUGH WARMING TO OCCUR SOUTH OF FRONT FOR TEMPERATURES IN THE UPPER 90S TO LOWER 100S AGAIN TODAY. ETA HAS BEEN TOO WARM WITH 850 TEMPERATURE PROJECTIONS LATELY...AND MOISTURE FROM SOUTHWEST UNITED STATES WILL PROVIDE AMPLE MID LEVEL CLOUDS. BOTTOM LINE...TEMPERATURES TODAY WILL BE SIMILAR TO THOSE OF YESTERDAY. MODELS BRING A MID LEVEL SHORT WAVE ACROSS THE FORECAST AREA TODAY. THE WAVE IS APPARENT IN THE WATER VAPOR IMAGERY...AND AZTEC PROFILER INDICATES WAVE WENT THROUGH THERE A FEW HOURS AGO. PLATTEVILLE PROFILER ALSO INDICATES THAT WAVE MAY BE SHARPER THAN ETA INDICATES...MORE IN LINE WITH GFS. CONVECTION FORMED WITH WAVE OVER NEW MEXICO EARLIER THIS EVENING. WITH MOISTURE INCREASING...SURFACE CONVERGENCE ALONG FRONT...AND SOME UPWARD VERTICAL VELOCITIES DUE SHORT WAVE...WILL REINTRODUCE A SLIGHT CHANCE OF CONVECTION THIS AFTERNOON AND TONIGHT. FRONT WILL BE THROUGH THE AREA TONIGHT PLACING THE FORECAST AREA IN UPSLOPE LOW LEVEL FLOW WEDNESDAY/WEDNESDAY NIGHT. SEE NO END TO THE ADVECTION OF PSEUDO MONSOON MOISTURE OVER COLORADO DURING THIS TIME. THE QUESTION WILL BE HOW FAR EAST THE RESULTING CONVECTION OVER THE COLORADO FRONT RANGE WILL GO. WITH SLIGHTLY COOLER MID LEVEL TEMPERATURES...CAPPING SHOULD NOT BE A PROBLEM. LOW LEVEL SHEAR WILL BE DECENT. GFS/ETA BOTH INDICATE SOME CONVECTION REACHING THE WESTERN FORECAST AREA WEDNESDAY NIGHT...AND WILL INDICATE A SLIGHT CHANCE THERE. SIMILAR REGIME WILL BE PRESENT THURSDAY. TEMPERATURES WILL BE COOLER DUE CLOUD COVER...WEAK COLD AIR ADVECTION...AND UPSLOPE FLOW. NEXT DECENT SHORTWAVE WILL ARRIVE SATURDAY AFTERNOON IN NORTHWEST FLOW ALOFT. WILL INDICATE A SLIGHT CHANCE OF CONVECTION THEN. OTHERWISE...LITTLE CHANGE TO THE EXTENDED PARTS OF FORECAST. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ MENTZER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 415 AM EDT TUE AUG 3 2004 .DISCUSSION... 00Z RAOBS/WATER VAPOR LOOP SHOW FAST NORTHWESTERLY FLOW INTO THE GREAT LAKES...BETWEEN BROAD LOW OVER HUDSON BAY/EASTERN CANADA AND HIGH OVER THE SOUTHERN PLAINS. A NUMBER OF EMBEDDED IN THE FAST FLOW UPSTREAM THROUGH THE HIGH PLAINS. SURFACE ANALYSIS SHOWS THE WEAK FRONT JUST ABOUT TO CENTRAL LOWER MICHIGAN/SOUTHERN WISCONSIN... ALTHOUGH RATHER DIFFUSE. OTHERWISE LOW PRESSURE UPSTREAM ACROSS THE CENTRAL HIGH PLAINS...WITH HIGH PRESSURE OVER THE CANADIAN PRAIRIES. MAIN FORECAST FOCUS IS WITH CONVECTION...FIRST TODAY AND THEN ON WEDNESDAY. MOST 00Z GUIDANCE IS CONTAMINATED BY VARYING DEGREES OF CONVECTIVE FEEDBACK. GFS CONTINUES TO BE WAY OVERDONE...AND NOW THE 00Z ETA HAD DEVELOPED SIMILAR PROBLEMS. ETA DPROG/DT AT F48 GOES FROM SURFACE FRONT NEAR TO THE TENNESSEE VALLEY WITH SURFACE RIDGE DOMINATING LOWER MICHIGAN PER THE 02/12Z RUN...TO 1003 SURFACE WAVE OVER INDIANA/OHIO WITH >1" QPF ACROSS SOUTHERN LOWER MICHIGAN PER THE CURRENT 03/00Z RUN. GFS CONTINUES TO BE MORE OVERDEVELOPED...AND FEATURES A 997 LOW OVER SOUTHERN LOWER. THE GFS IS SO OVERDONE THAT IT ACTUALLY CHANGES THE SYNOPTIC FLOW AT 500MB...BRINGING IN SOME BRIEF RIDGING 12Z WEDNESDAY AND BACKING THE MID-LEVEL FLOW TO THE SOUTHWEST...ALLOWING CONVECTION TO PROPAGATE EVEN FARTHER NORTH. 00Z CANADIAN GLOBAL AND REGIONAL BOTH SHOW SIMILAR OVERDEVELOPED WAVES...WHICH ARE CORRESPONDINGLY FARTHER NORTH. PROBLEMS BEGIN WITH GRIDSCALE FEEDBACK FROM CONVECTION TONIGHT ACROSS THE CENTRAL PLAINS. SHORTWAVE CURRENTLY OVER COLORADO LOOKS TO CREST THE RIDGE AND INTERACT WITH A VERY UNSTABLE AIRMASS /SIMILAR TO THE ONE OBSERVED YESTERDAY ACROSS THE PLAINS/. FOR NOW WILL THROW OUT MOST 00Z GUIDANCE. NGM HAS A MORE REASONABLE REPRESENTATION...WITH A WEAK WAVE ALONG THE FRONT OVER THE OHIO VALLEY. IT HAS ALSO TRENDED A BIT STRONGER WITH THE WAVE...AND DOES BRING SOME QPF FARTHER NORTH INTO LOWER MICHIGAN INITIALLY FOR TODAY...QUESTION REVOLVES AROUND THE DIFFUSE SURFACE FRONT JUST NORTH OF THE CWA. ETA/GFS HAVE BEEN TOO FAST DROPPING THIS FRONT SOUTHWARD...WITH THE 03Z RUC INITIALLY SLOWER AND BETTER. HOWEVER EVEN THE 06Z RUN JUMPS THE FRONT SOUTH QUICKLY THIS MORNING...WHICH SEEMS UNREASONABLE GIVEN THE MOIST AND UNSTABLE AIRMASS ACROSS THE STATE...ESPECIALLY ONCE THE SUN COMES UP. THEREFORE WILL HOLD ONTO POPS LONGER THAN MODELS WOULD INDICATE... KEEPING CHANCE NORTH/SCATTERED SOUTH THROUGH THE DAY. WITH SOME LINGERING INSTABILITY AND POTENTIAL FORCING WILL ALSO KEEP A CHANCE GOING ACROSS THE SOUTH THIS EVENING...BUT DRY OVERNIGHT. NOT MUCH IN THE WAY OF COLD ADVECTION WITH THIS FRONT. ALSO SKIES HAVE PRETTY MUCH CLEARED OUT OVERNIGHT BEHIND THE EARLIER ROUNDS OF STORMS. SOME AREAS ESPECIALLY ACROSS THE SOUTHERN CWA COULD GET SOME DECENT INSOLATION THIS MORNING...AND REACH TEMPERATURES IN THE UPPER 80S SIMILAR TO YESTERDAY. VISFOG SATELLITE SHOWS SOME CLOUDS TRYING TO DEVELOP...SO WILL START THE DAY OFF AS PARTLY SUNNY. ALTHOUGH WITH SOME CLEAR SPOTS...LIGHT WIND AND NEARLY SATURATED LOW LEVELS FROM RAIN YESTERDAY AFTERNOON AND OVERNIGHT...STILL COULD SEE SOME FOG THIS MORNING. NOW FOR WEDNESDAY. GFS HAS BEEN ALL OVER THE PLACE RECENTLY DUE TO POOR HANDLING OF CONVECTION...AND NOW ETA AND CANADIAN HAVE JOINED IN. IT IS EASY TO DISCOUNT THESE SOLUTIONS DUE TO GRIDSCALE FEEDBACK. WHAT IS SOMEWHAT TROUBLING IS THAT ALL OF THESE MODELS HAVE DEVELOPED SIMILAR PROBLEMS OVER THE SAME REGION...EVEN WITH DIFFERENT CONVECTIVE PARAMETERIZATIONS. ALSO OF INTEREST IS THE 02/12Z ECMWF. IT ALSO SHOWS A SIMILAR RADICAL CHANGE FROM ITS 02/00Z RUN...FROM A FRONT NEAR THE OHIO/TENNESSEE VALLEYS TO A SURFACE WAVE ALONG THE FRONT TRACKING NEAR CHICAGO. A QUICK LOOK AT THE 03/00Z RUN IS BASICALLY SIMILAR TO ITS 12Z RUN. THIS INDICATES THAT THE ECMWF PICKED UP ON A SYNOPTIC CHANGE 12 HOURS BEFORE THE ETA. UNFORTUNATELY IT IS HARD TO DIAGNOSE THE MODEL GIVEN OUR LIMITED DATA SET. HOWEVER IT DOES LOOK LIKE A REALISTIC TREND THAT BEARS ATTENTION. STRENGTHENING UPPER LEVEL JET/NORTHERN STREAM WAVE NEAR MANITOBA WILL DROP DOWN THROUGH THE REGION...HELPING THE CANADIAN LOW DROP SOUTHWARD THROUGH LATE WEEK...AND LOWERING HEIGHTS ACROSS THE REGION. INITIALLY THIS INCREASES THE MID-LEVEL CONFLUENCE ACROSS THE STATE...WHICH WOULD HELP KEEP PRECIP SOUTH OF THE STATE. HOWEVER THE UNSEASONABLE STRONG JET WILL ALSO SHIFT DOWNSTREAM...BRINGING SOME UPPER DIVERGENCE VICINITY OF THE RIGHT-REAR QUADRANT INTO PLAY. THIS MAY BE A REASONABLE SYNOPTIC FEATURE LEADING TO THE SURFACE WAVE DEVELOPMENT. 10KM TAQ-RUC AND NCAR MM5 ALSO SHOW SIMILAR SURFACE PATTERNS TO THE ECMWF. THESE MODELS TRY TO BRING QPF INTO THE SOUTHERN GREAT LAKES...LOOKING MORE LIKE OVERRUNNING PRECIP AS OPPOSED TO A CONVECTIVE COMPLEX...AND WEAKEN IT WITH TIME ON WEDNESDAY. WAS TEMPTED TO KEEP A DRY FORECAST ON WEDNESDAY... ALLOWING ANOTHER MODEL RUN TO CHECK FOR CONSISTENCY TO PREVENT A FLIP-FLOP. HOWEVER GIVEN SUPPORT FROM RUC/MM5 AND ECMWF...FEEL COMFORTABLE ADDING A CHANCE OF RAIN SHOWERS BACK FOR WEDNESDAY. WILL HOLD OFF ON THUNDER FOR NOW GIVEN OUR PLACEMENT NORTH OF THE LOW AND NATURE OF THE WEAKENING CONVECTION DURING THE DAY. IF OTHER 00Z SOLUTIONS PAN OUT...IT WOULD NOT BE UNREASONABLE TO INCREASE POPS OR ADD THUNDER...BUT FOR NOW A LOW CHANCE SEEMS LIKE THE BEST BET AS MAIN PRECIP SHOULD BECOME INCREASINGLY TIED TO THE SURFACE BOUNDARY AS WE DESTABILIZE DURING THE DAY. && .DTX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ BRAVENDER EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 400 AM EDT TUE AUG 3 2004 .SHORT TERM... VERY CHALLENGING SHORT TERM FORECAST DUE TO CONSIDERABLE SHORT RANGE MODEL DISCREPANCIES AND LARGE RUN TO RUN CHANGES. MODELS ARE ALSO SUFFERING FROM SERIOUS CONVECTIVE FEEDBACK PROBLEMS THAT ARE RESULTING IN INFLATED QPF FORECASTS FOR WEDNESDAY. AT 06Z THE SFC WX MAP SHOWS A SLOW MOVING COLD FRONT EXTENDS FROM NORTH CENTRAL LWR MI WSW ACROSS CENTRAL WISCONSIN. OUR FIRST FORECAST CHALLENGE IS TO DETERMINE WHETHER WE'LL GET ANY PCPN TODAY IN ASSOCIATION WITH THAT FEATURE. THE RUC 500 HGT/VORT PROG INDICATES MOST OF OUR AREA WILL BE IN NVA THROUGH THIS A.M. HOWEVER, WE'RE STILL GOING TO GENERATE SOME SURFACE BASED INSTABILITY THIS MORNING OUT AHEAD OF THE BOUNDARY, PARTICULARLY ACROSS OUR SOUTHERN CWA. THIS COMBINED WITH SFC CONVERGENCE NEAR THE BOUNDARY MAY BE ENOUGH TO TRIGGER A FEW SHOWERS AND STORMS. THEREFORE, WE'LL CONTINUE TO GO WITH LOW CHC POPS FOR SHOWERS/TSTORMS ACROSS OUR SOUTHERN CWA. WE'LL HAVE DRY CONDITIONS ACROSS OUR AREA TONIGHT IN N TO NE FLOW NORTH OF THAT BOUNDARY AND OUT AHEAD OF A DEVELOPING SFC LOW IN THE PLAINS STATES. THE FCST FOR WEDNESDAY IS VERY TRICKY. THE ETA HAS NOW COME INTO LINE WITH THE GFS AND CANADIAN GUIDANCE IN SHOWING PRETTY SIGNIFICANT SFC LOW DEVELOPMENT TO OUR WEST LATE TONIGHT. BOTH GFS AND ETA GUIDANCE CONTINUE TO INTENSIFY THE LOW AS IT TRACKS EAST AND INDICATE POTENTIAL FOR SIGNIFICANT RAINFALL ACROSS OUR AREA (ONE TO TWO INCHES WORTH... POSSIBLY EVEN MORE THAN THAT). STRONG SHORTWAVE ENERGY IS NOTED OVER THE ROCKIES AND AS IT COMES OVER THE TOP OF THE RIDGE OUT THERE, WE SUSPECT A SFC LOW WILL DEVELOP AND TRACK EAST INTO OUR REGION WEDNESDAY. HOWEVER, AT THIS TIME WE STILL BELIEVE RGNL CANADIAN/GFS/ETA GUIDANCE ARE ALL OVERDONE WITH THE STRENGTH OF THE SFC LOW AND QPF. GUIDANCE IS SUFFERING FROM SERIOUS CONVECTIVE FEEDBACK PROBLEMS WHICH ARE CLEAR IN THE PROGGED 500 HGT/VORT FIELDS. ADDITIONALLY, SHORT RANGE ENSEMBLES STILL POINT TOWARDS A FURTHER SOUTH SFC LOW SOLUTION FOR WED. COMPARING THE 00Z ETA TO IT'S PREVIOUS RUN INDICATES JUST HOW RADICALLY DIFFERENT AND ERRATIC IT IS FROM RUN TO RUN (BULLSEYE OF NEARLY 4 INCHES OF RAIN IN 12 HRS OVER IOWA BETWEEN 00Z AND 12Z WED, WHEREAS THE PREVIOUS RUN OF THE ETA ONLY HAD ABOUT 4 TENTHS OF AN INCH CUMULATIVE RAINFALL IN THAT AREA FOR THE SAME TWELVE HOUR TIME PERIOD). THIS IS IN RESPONSE TO THE UNREALISTICALLY STRONG H5 VORT IT HAS NOW GENERATED OVER IOWA (MAGNITUDE 35 OR SO). WITH ALL THIS UNCERTAINTY, WE THINK AT THIS POINT IT IS WISEST TO AT LEAST INTRODUCE CHANCE POPS FOR RAIN WED, BUT NOT GET CARRIED AWAY WITH IT IN SPITE OF WHAT THE GFS/ETA/RGNL CANADIAN SHOW IN TERMS OF QPF. IF MODELS CONTINUE TO SUGGEST SIGNIFICANT SFC LOW DEVELOPMENT FARTHER NORTH AND POTENTIAL FOR A GOOD SOAKING, THE DAY SHIFT CAN BUMP POPS UP TO LIKELY OR EVEN CATEGORICAL FOR WED IF NECESSARY. WE'LL LINGER LOW CHANCE POPS INTO WEDNESDAY NIGHT (MAINLY EARLY) BEFORE THE SFC LOW DEPARTS WELL EAST OF OUR AREA. WE'LL HAVE DRY CONDITIONS THURSDAY AND THURSDAY NIGHT WITH THE SFC HIGH PRESSURE RIDGE TO OUR NW IN CONTROL OF OUR WX AND DRY NORTHERLY FLOW. TEMPS WILL BE QUITE COOL ACROSS OUR AREA BY 12Z FRI AND WE WILL LIKELY HAVE MANY TEMP READINGS IN THE 40'S AROUND DAYBREAK FRIDAY! .LONG TERM... STARTING WITH FRIDAY SOUTHWEST LOWER MICHIGAN IS BETWEEN A CLOSED UPPER LOW OVER NEW YORK STATE...AND A LARGE SCALE RIDGE ACROSS THE UPPER PLAINS. THROUGH MONDAY THIS RIDGE FLATTENS AND BUILDS EAST BEHIND THE DEPARTING UPPER LOW. FOR SOUTHWEST LOWER MICHIGAN...THIS PATTERN SHOULD LEAD TO TRANQUIL WEATHER WITH A GRADUAL WARMING TREND. BASED ON THE 850 MB THERMAL TROUGH ACROSS MI ON FRIDAY...WE SHOULD BE WELL BELOW NORMAL. MORE SEASONABLE TEMPERATURES THEN RETURN BY MONDAY. AS FOR RAIN...THE CHANCES LOOK LOW...BUT A COLD FRONT IS SEEN ON THE GFS FOR TUESDAY...WITH THE ECMWF A LITTLE FASTER. && .GRR WATCHES/WARNINGS/ADVISORIES...NONE. && $$ LAURENS MJS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 400 AM CDT TUE AUG 3 2004 .DISCUSSION... I AM EXPECTING A MARKED INCREASE IN CONVECTION IN SOUTHERN IOWA DURING THE NEXT COUPLE OF HOURS. LIKE YESTERDAY MORNING, THE 310K ISENTROPIC SURFACE (ANALYZED BY THE RUC) SEEMS TO BE TOOL MOST USEFUL FOR DETERMINING LIFT FOR CONVECTIVE DEVELOPMENT. THE FOG CHANNEL SHOWS THE DEVELOPMENT OF A BAND OF STRATUS OVER SOUTHWEST IOWA DOWN THROUGH MARYVILLE, MISSOURI. THIS NARROW STRIP OF CLOUDS IS LIKELY THE DEMARCATION OF THE EDGE OF THE CAP. SHALLOW MOISTURE IS LIKELY TRAPPED BELOW THE CAP. SO FOR THIS MORNING, I HAVE INCLUDED 30 PERCENT CHANCES FOR THUNDER EAST OF A LINE FROM BETHANY TO MOBERLY. I MAY NEED TO INCREASE PROBABILITIES IF CONVECTION INCREASES LIKE IT HAS THE LAST FEW MORNINGS, BUT 00Z RAOBS INDICATE THAT THE MOISTURE LAYER IS MORE SHALLOW THAN RECENT DAYS, SO THUNDER MAY BE A BIT MORE SPOTTY. DEWPOINTS REACHED OPPRESSIVE LEVELS YESTERDAY IN EASTERN KANSAS AND WESTERN MISSOURI. UPPER 70 DEWPOINTS PUSHED HEAT INDICES WELL ABOVE 105 DEGREES LATE IN THE DAY IN KANSAS CITY AND SAINT JOSEPH. DEWPOINTS HAVE ONLY DROPPED A FEW DEGREES OVERNIGHT. YESTERDAY A LIGHT SOUTH WIND, STRONG EVAPOTRANSPIRATION, SIGNIFICANT CAPPING, AND MOISTURE POOLING ALONG A STATIONARY BOUNDARY IN NORTHERN MISSOURI CONTRIBUTED TO THE STAGGERING LEVELS OF HUMIDITY. TODAY, I AM BANKING ON MORE MIXING THIS AFTERNOON TO CUT DEWPOINTS DOWN A FEW DEGREES IN THE KANSAS CITY AND SAINT JOSEPH AREAS. AFTERNOON DEWPOINTS IN EXCESS OF 75 DEGREES ARE LIKELY FROM MARYVILLE TO CHILLICOTHE, THOUGH WHERE WINDS WILL BE LIGHTER NEAR THE STATIONARY FRONT. TEMPERATURES ACROSS THE REGION SHOULD BE TWO OR THREE DEGREES WARMER TODAY WITH COMPRESSIONAL WARMING AS THE FRONT TO OUR NORTHWEST STRENGTHENS. HEAT ADVISORY CRITERIA (HEAT INDEX GREATER THAN 105 DEGREES FOR 3 HOURS) SHOULD BE MET IN EASTERN KANSAS AND A SIGNIFICANT CHUNK OF NORTHERN MISSOURI. FOR NOW I WILL KEEP BETHANY, KIRKSVILLE, MACON, AND MOBERLY OUT OF THE ADVISORY SINCE CLOUDS FROM CONVECTION IN IOWA THIS MORNING WILL SLOW HEATING. HEAT WAVES HAVE BEEN VERY SHORT LIVED THIS SUMMER, AND OUR CURRENT ONE WILL BE NO EXCEPTION. WATER VAPOR IMAGERY THIS MORNING SHOWS THE LONGWAVE PATTERN RETURNING TO OUR PREDOMINANT FLOW FOR THIS SUMMER. A DEEP TROUGH OFF THE NORTHWEST COAST, RIDGE OVER THE NORTHERN ROCKIES, AND DOWNSTREAM TROUGHING OVER CENTRAL CANADA. THIS SET UP HAS DUMPED COOLER THAN AVERAGE TEMPERATURES INTO THE CENTRAL UNITED STATES TIME AND AGAIN THIS SUMMER, AND IS POISED TO DO IT AGAIN. THE LEADING EDGE OF THE COOLER AIR WILL ARRIVE TOMORROW. THE GFS CONTINUES TO TREND COOLER WITH A HIGHLY AMPLIFIED EASTERN U.S. TROUGH BY THE END OF THE WEEK. I'VE LOWERED TEMPERATURES AGAIN FOR THE SECOND HALF OF THE WEEK, AND THE DAY SHIFT MAY NEED TO DROP TEMPERATURES EVEN MORE FOR THURSDAY THROUGH SATURDAY. KOCH .PREV DISCUSSION... 728 PM MON... WITH THE HEAT INDICES STILL RUNNING AROUND THE 104 TO 109 RANGE IN THE KANSAS CITY METRO AREA AT 7 PM...AND MORE HOT WEATHER EXPECTED ON TUESDAY...WILL GO AHEAD AND ISSUE A HEAT ADVISORY FOR THE METRO AREA STARTING THIS EVENING THROUGH THE DAY ON TUESDAY. HEAT ISLAND EFFECT WILL DEFINITELY BE A FACTOR IN TEMPERATURES TONIGHT...AND CUMULATIVE EFFECT AFTER THE HOT DAY TODAY IN THE METRO AREA IS A CONCERN. WILL HOLD OFF GOING INTO OTHER AREAS WITH THIS ADVISORY AT THIS POINT. NORTHWEST MISSOURI MAY HAVE SOME CLOUDS AND AN OUTFLOW BOUNDARY AFFECTING THE REGION ON TUESDAY FROM STORMS EXPECTED TO BE IN IOWA TONIGHT. PC && 356 PM MON... WARM AIR ADVECTION ACTIVITY ASSOCIATED WITH MCS TO THE NORTH EXITED THE EASTERN CWA AROUND NOON TODAY. LEFTOVER CLOUDS PUT A DAMPER ON TEMPERATURES AT FIRST...BUT BY 20Z ALL TEMPS WERE JUST A COUPLE DEG COOLER THAN FORECAST. HEAT INDICES WERE BETWEEN 100 AND 105...WITH THE HIGHEST JUST AT KMCI WHERE THE DEWPOINT IS AROUND 3 DEG HIGHER THAN SURROUNDING SITES. THE FORECAST FOR THE SHORT TERM FOCUSES ON THESE MAIN SYMPTOMS AGAIN...HEAT AND RAIN. SURFACE LOW JUST TO THE NORTH SHOULD GENERATE ANOTHER ROUND OF STORMS TONIGHT. 12Z ETA/GFS BOTH SHOW THAT WHEN THIS ACTIVITY LINES OUT IT SHOULD BE ACROSS IA. (NOTE: 18Z ETA HAS DROPPED THIS FARTHER SOUTH.) HAVE KEPT POPS FOR NORTHEASTERN MO...AS CORFIDI AND H850-300 THICKNESS WOULD DROP STORMS EAST AND THEN DUE SOUTH. CAPPING SHOULD BE IN PLACE FARTHER WEST...WITH NORTHEAST MISSOURI POSSIBLY ON THE EDGE OF IT. TEMPERATURES ON TUESDAY ARE TRICKY. HAVE KEPT GOING FORECAST HIGHS WHICH ARE MAINLY IN THE MID 90S...A FEW DEGREES COOLER THAN GUIDANCE WHICH HAS BEEN ON THE WARM SIDE. LEFTOVER CLOUDS MAY BE IN PLACE TOMORROW TOO. THE MAIN CONCERN IS WITH THE DEWPOINTS. THEY ARE HIGHER TODAY THAN PREVIOUSLY THOUGHT...WHICH IS WHAT IS GIVING US MARGINAL ADVISORY CRITERIA HEAT INDICES TODAY. IT LOOKS LIKE WE WILL BE CLOSE TO CRITERIA AGAIN TOMORROW...EITHER WITH DEWPOINTS AGAIN OR AN EVEN HOTTER SURFACE TEMP. HAVE UPDATED THE HWO TO INCLUDE HEAT...BUT MID CREW WILL NEED TO TAKE ANOTHER LOOK. BY TUES EVENING...A SURFACE FRONT IS EXPECTED TO BE IN NORTHERN KANSAS. THIS WILL KEEP TEMPS STEAMY IN THE EVENING. MID LEVEL TEMPS ARE WARM WHICH SHOULD KEEP US DRY IN THE AFTERNOON...BUT WITH FROPA HAVE KEPT THE LOW CHANCE POPS IN PLACE OVERNIGHT. THIS WILL CONTINUE THROUGH WED UNTIL THE FRONT EXITS. AFTER WHICH...SOMEWHAT COOLER TEMPERATURES ENTER THE ARENA. IN THE EXTENDED PORTION OF THE FORECAST...MEDIUM RANGE MODEL SOLUTIONS AGREE ON THE AMPLIFICATION OF THE MID/UPPER TROUGH OVER THE EASTERN CONUS. THIS WILL SQUELCH THE WESTERN RIDGE...AND PREVENT THE OCCURRENCE OF THE PREVIOUSLY ADVERTISED HOT SPELL. ANTICIPATE TEMPERATURES TO BE AROUND 5 DEGREES BELOW CLIMATOLOGY RATHER THAN ABOVE. HAVE CONTINUED THE LOWERING TREND OF TEMPERATURES ON THURSDAY AND FRIDAY...WITH PROGGED 850 MB TEMPS NOW BETWEEN 12C AND 14C. WILL NOT STRAY FAR FROM MEX GUIDANCE. AS THE EASTERN TROUGH SHIFTS EAST OVER THE WEEKEND...HEIGHTS WILL GRADUALLY RISE...CAUSING TEMPERATURES TO SLOWLY MODERATE INTO THE BEGINNING OF NEXT WEEK. PRECIPITATION CHANCES FOR THE MAJORITY OF THE PERIOD WILL BE BELOW 20 PERCENT AS THE FORECAST AREA REMAINS BETWEEN TWO AFOREMENTIONED LARGE SCALE FEATURES. THE ECMWF AND GFS MODELS FORECAST A SHORTWAVE TO TOP THE NORTHERN PERIPHERY OF THE RIDGE AND PUSH A COLD FRONT ACROSS THE NORTHERN PLAINS OVER DAYS 6 AND 7...BUT WILL NOT INTRODUCE POPS AT THIS TIME DUE TO TIMING CONCERNS. LVQ/LS && .EAX WATCHES/WARNINGS/ADVISORIES... KS...HEAT ADVISORY FROM 400 AM CDT TUESDAY UNTIL 800 PM CDT TUESDAY FOR ZONES KSZ025...KSZ057...KSZ060...KSZ102>105. MO...HEAT ADVISORY FROM 400 AM CDT TUESDAY UNTIL 800 PM CDT TUESDAY FOR ZONES MOZ001>004...MOZ011>014...MOZ020>023...MOZ028>032... MOZ037>040...MOZ043>046...MOZ053>054. && $$ KOCH mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1025 AM MDT TUE AUG 3 2004 .DISCUSSION...UPDATED MAINLY FOR WIND SHIFT OCCURRING AREAWIDE THIS MORNING. LOW PRESSURE WAS CENTERED OVER NORTH CENTRAL TO NORTHEAST NEBRASKA...WHERE A LOW LEVEL JET WAS FEEDING INTO AN IMPRESSIVE MCS/POTENTIAL MCC OVER SOUTH DAKOTA. A TRAILING COLD FRONT HAD BEGUN TO MOVE SOUTHWARD THROUGH THE NEBRASKA PANHANDLE. MEANWHILE...SURFACE ANALYSIS AND RADAR FINELINE INDICATE A PREFRONTAL PRESSURE TROF MOVING QUICKLY ACROSS THE TRI STATE REGION THIS MORNING...SHIFTING WINDS TO THE NORTH AT 15 TO 20 MPH. IT IS TEMPTING TO REMOVE THE SLIGHT CHANCE OF THUNDERSTORMS FROM THE AFTERNOON/EVENING PERIOD BECAUSE THE TROF WILL SCOUR OUT WHAT LITTLE LOW LEVEL MOISTURE WAS IN PLACE...AND DRY MID LEVEL AIR IS MOVING IN FROM COLORADO. ON THE OTHER HAND...RUC SOUNDINGS DO INDICATE MODEST INSTABILITY...AND WOULD PREFER TO MAINTAIN CONTINUITY WITH THE PREVIOUS FORECAST RATHER THAN REMOVE POPS AND HAVE A FEW THUNDERSTORMS DEVELOP. WILL TONE DOWN THE HWO THOUGH. THE MOST LIKELY AREAS FOR THUNDERSTORMS WILL BE FROM HILL CITY TO GOVE EARLY THIS AFTERNOON WITH THE PASSAGE OF THE TROF...AND THEN POSSIBLY ALONG THE PALMER DIVIDE IN EASTERN COLORADO EARLY THIS EVENING...THOUGH THAT AREA WILL HAVE VERY DRY MID LEVEL AIR AND VERY LITTLE INSTABILITY. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ BURKE ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND RAPIDS MI 1155 AM EDT TUE AUG 3 2004 .UPDATE... SFC FRONT IS MAKING ITS WAY THROUGH THE NORTHERN CWA ATTM...AND CAD DEW POINT HAS DROPPED TO THE LOWER 50S. HOWEVER...THERE SHOULD STILL BE SOME OVERRUNNING RAINS DEVELOPING ALONG THE FRONT ACROSS SOUTHERN WISCONSIN THIS AFTERNOON AND SOME OF THAT MAY CLIP THE SW GRR FORECAST AREA. WILL KEEP CHANCE POPS GOING FOR THE SOUTHERN ONE THIRD OF THE CWA AS SCATTERED CONVECTION IS POSSIBLE ALONG THE FRONT THIS AFTERNOON...GIVEN THE COMBINATION OF INCREASING INSTABILITY FROM SFC HEATING AND LOW LEVEL CONVERGENCE NEAR THE FRONT. ZONE UPDATE OUT. PREVIOUS DISCUSSION... .SHORT TERM... VERY CHALLENGING SHORT TERM FORECAST DUE TO CONSIDERABLE SHORT RANGE MODEL DISCREPANCIES AND LARGE RUN TO RUN CHANGES. MODELS ARE ALSO SUFFERING FROM SERIOUS CONVECTIVE FEEDBACK PROBLEMS THAT ARE RESULTING IN INFLATED QPF FORECASTS FOR WEDNESDAY. AT 06Z THE SFC WX MAP SHOWS A SLOW MOVING COLD FRONT EXTENDS FROM NORTH CENTRAL LWR MI WSW ACROSS CENTRAL WISCONSIN. OUR FIRST FORECAST CHALLENGE IS TO DETERMINE WHETHER WE'LL GET ANY PCPN TODAY IN ASSOCIATION WITH THAT FEATURE. THE RUC 500 HGT/VORT PROG INDICATES MOST OF OUR AREA WILL BE IN NVA THROUGH THIS A.M. HOWEVER, WE'RE STILL GOING TO GENERATE SOME SURFACE BASED INSTABILITY THIS MORNING OUT AHEAD OF THE BOUNDARY, PARTICULARLY ACROSS OUR SOUTHERN CWA. THIS COMBINED WITH SFC CONVERGENCE NEAR THE BOUNDARY MAY BE ENOUGH TO TRIGGER A FEW SHOWERS AND STORMS. THEREFORE, WE'LL CONTINUE TO GO WITH LOW CHC POPS FOR SHOWERS/TSTORMS ACROSS OUR SOUTHERN CWA. WE'LL HAVE DRY CONDITIONS ACROSS OUR AREA TONIGHT IN N TO NE FLOW NORTH OF THAT BOUNDARY AND OUT AHEAD OF A DEVELOPING SFC LOW IN THE PLAINS STATES. THE FCST FOR WEDNESDAY IS VERY TRICKY. THE ETA HAS NOW COME INTO LINE WITH THE GFS AND CANADIAN GUIDANCE IN SHOWING PRETTY SIGNIFICANT SFC LOW DEVELOPMENT TO OUR WEST LATE TONIGHT. BOTH GFS AND ETA GUIDANCE CONTINUE TO INTENSIFY THE LOW AS IT TRACKS EAST AND INDICATE POTENTIAL FOR SIGNIFICANT RAINFALL ACROSS OUR AREA (ONE TO TWO INCHES WORTH... POSSIBLY EVEN MORE THAN THAT). STRONG SHORTWAVE ENERGY IS NOTED OVER THE ROCKIES AND AS IT COMES OVER THE TOP OF THE RIDGE OUT THERE, WE SUSPECT A SFC LOW WILL DEVELOP AND TRACK EAST INTO OUR REGION WEDNESDAY. HOWEVER, AT THIS TIME WE STILL BELIEVE RGNL CANADIAN/GFS/ETA GUIDANCE ARE ALL OVERDONE WITH THE STRENGTH OF THE SFC LOW AND QPF. GUIDANCE IS SUFFERING FROM SERIOUS CONVECTIVE FEEDBACK PROBLEMS WHICH ARE CLEAR IN THE PROGGED 500 HGT/VORT FIELDS. ADDITIONALLY, SHORT RANGE ENSEMBLES STILL POINT TOWARDS A FURTHER SOUTH SFC LOW SOLUTION FOR WED. COMPARING THE 00Z ETA TO IT'S PREVIOUS RUN INDICATES JUST HOW RADICALLY DIFFERENT AND ERRATIC IT IS FROM RUN TO RUN (BULLSEYE OF NEARLY 4 INCHES OF RAIN IN 12 HRS OVER IOWA BETWEEN 00Z AND 12Z WED, WHEREAS THE PREVIOUS RUN OF THE ETA ONLY HAD ABOUT 4 TENTHS OF AN INCH CUMULATIVE RAINFALL IN THAT AREA FOR THE SAME TWELVE HOUR TIME PERIOD). THIS IS IN RESPONSE TO THE UNREALISTICALLY STRONG H5 VORT IT HAS NOW GENERATED OVER IOWA (MAGNITUDE 35 OR SO). WITH ALL THIS UNCERTAINTY, WE THINK AT THIS POINT IT IS WISEST TO AT LEAST INTRODUCE CHANCE POPS FOR RAIN WED, BUT NOT GET CARRIED AWAY WITH IT IN SPITE OF WHAT THE GFS/ETA/RGNL CANADIAN SHOW IN TERMS OF QPF. IF MODELS CONTINUE TO SUGGEST SIGNIFICANT SFC LOW DEVELOPMENT FARTHER NORTH AND POTENTIAL FOR A GOOD SOAKING, THE DAY SHIFT CAN BUMP POPS UP TO LIKELY OR EVEN CATEGORICAL FOR WED IF NECESSARY. WE'LL LINGER LOW CHANCE POPS INTO WEDNESDAY NIGHT (MAINLY EARLY) BEFORE THE SFC LOW DEPARTS WELL EAST OF OUR AREA. WE'LL HAVE DRY CONDITIONS THURSDAY AND THURSDAY NIGHT WITH THE SFC HIGH PRESSURE RIDGE TO OUR NW IN CONTROL OF OUR WX AND DRY NORTHERLY FLOW. TEMPS WILL BE QUITE COOL ACROSS OUR AREA BY 12Z FRI AND WE WILL LIKELY HAVE MANY TEMP READINGS IN THE 40'S AROUND DAYBREAK FRIDAY! .LONG TERM... STARTING WITH FRIDAY SOUTHWEST LOWER MICHIGAN IS BETWEEN A CLOSED UPPER LOW OVER NEW YORK STATE...AND A LARGE SCALE RIDGE ACROSS THE UPPER PLAINS. THROUGH MONDAY THIS RIDGE FLATTENS AND BUILDS EAST BEHIND THE DEPARTING UPPER LOW. FOR SOUTHWEST LOWER MICHIGAN...THIS PATTERN SHOULD LEAD TO TRANQUIL WEATHER WITH A GRADUAL WARMING TREND. BASED ON THE 850 MB THERMAL TROUGH ACROSS MI ON FRIDAY...WE SHOULD BE WELL BELOW NORMAL. MORE SEASONABLE TEMPERATURES THEN RETURN BY MONDAY. AS FOR RAIN...THE CHANCES LOOK LOW...BUT A COLD FRONT IS SEEN ON THE GFS FOR TUESDAY...WITH THE ECMWF A LITTLE FASTER. && .GRR WATCHES/WARNINGS/ADVISORIES...NONE. && $$ OSTUNO mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1100 AM EDT TUE AUG 3 2004 .UPDATE... WEAK FRONTAL BOUNDARY SAGGING SOUTH THROUGH THE CWA THIS MORNING. SURFACE DEW POINTS IN THE MID 60S TO AROUND 70 DEGREES. WITH MAXES CLIMBING WELL INTO THE 80S TO AROUND 90 DEGREES...CAPES TO CLIMB TO 2000 J/KG ACROSS SOUTH CENTRAL LOWER MICHIGAN. MOST OF SURFACE CONVERGENCE/MOISTURE POOLING EXPECTED TO BE ACROSS SOUTH CENTRAL LOWER MICHIGAN...AS THE FRONAL BOUNDARY BECOMES MORE NORTH TO SOUTH ORIENTATED...DUE THE DIFFERENTIAL HEATING OFF THE LAND/WATER. THE BIG QUESTION IS HOW SOON WILL THUNDERSTORMS DEVELOP OVER THE OHIO VALLEY...WHICH WILL HELP TO LIMIT THE AMOUNT OF MOISTURE AND INSTABILITY OVER SOUTHERN LOWER MICHIGAN. DECIDED TO MENTION AN ISOLATED MARGINAL SEVERE STORM ACROSS THE FAR WESTERN PART OF THE CWA. CAPES WILL BE CONSIDERABLY LESS TODAY COMPARED TO YESTERDAY. NONE-THE-LESS...WIND FIELDS ARE MUCH MORE FAVORABLE...AS 50+ KT JET AT 500 MB MOVES INTO NORTHERN LOWER MICHIGAN. LOWERED POPS NEAR THE LAKES...OTHERWISE FEW CHANGES TO THE ZONES. UPDATED ZONES ALREADY SENT OUT. SF .DISCUSSION ISSUED AT 415 AM... 00Z RAOBS/WATER VAPOR LOOP SHOW FAST NORTHWESTERLY FLOW INTO THE GREAT LAKES...BETWEEN BROAD LOW OVER HUDSON BAY/EASTERN CANADA AND HIGH OVER THE SOUTHERN PLAINS. A NUMBER OF EMBEDDED IN THE FAST FLOW UPSTREAM THROUGH THE HIGH PLAINS. SURFACE ANALYSIS SHOWS THE WEAK FRONT JUST ABOUT TO CENTRAL LOWER MICHIGAN/SOUTHERN WISCONSIN... ALTHOUGH RATHER DIFFUSE. OTHERWISE LOW PRESSURE UPSTREAM ACROSS THE CENTRAL HIGH PLAINS...WITH HIGH PRESSURE OVER THE CANADIAN PRAIRIES. MAIN FORECAST FOCUS IS WITH CONVECTION...FIRST TODAY AND THEN ON WEDNESDAY. MOST 00Z GUIDANCE IS CONTAMINATED BY VARYING DEGREES OF CONVECTIVE FEEDBACK. GFS CONTINUES TO BE WAY OVERDONE...AND NOW THE 00Z ETA HAD DEVELOPED SIMILAR PROBLEMS. ETA DPROG/DT AT F48 GOES FROM SURFACE FRONT NEAR TO THE TENNESSEE VALLEY WITH SURFACE RIDGE DOMINATING LOWER MICHIGAN PER THE 02/12Z RUN...TO 1003 SURFACE WAVE OVER INDIANA/OHIO WITH >1" QPF ACROSS SOUTHERN LOWER MICHIGAN PER THE CURRENT 03/00Z RUN. GFS CONTINUES TO BE MORE OVERDEVELOPED...AND FEATURES A 997 LOW OVER SOUTHERN LOWER. THE GFS IS SO OVERDONE THAT IT ACTUALLY CHANGES THE SYNOPTIC FLOW AT 500MB...BRINGING IN SOME BRIEF RIDGING 12Z WEDNESDAY AND BACKING THE MID-LEVEL FLOW TO THE SOUTHWEST...ALLOWING CONVECTION TO PROPAGATE EVEN FARTHER NORTH. 00Z CANADIAN GLOBAL AND REGIONAL BOTH SHOW SIMILAR OVERDEVELOPED WAVES...WHICH ARE CORRESPONDINGLY FARTHER NORTH. PROBLEMS BEGIN WITH GRIDSCALE FEEDBACK FROM CONVECTION TONIGHT ACROSS THE CENTRAL PLAINS. SHORTWAVE CURRENTLY OVER COLORADO LOOKS TO CREST THE RIDGE AND INTERACT WITH A VERY UNSTABLE AIRMASS /SIMILAR TO THE ONE OBSERVED YESTERDAY ACROSS THE PLAINS/. FOR NOW WILL THROW OUT MOST 00Z GUIDANCE. NGM HAS A MORE REASONABLE REPRESENTATION...WITH A WEAK WAVE ALONG THE FRONT OVER THE OHIO VALLEY. IT HAS ALSO TRENDED A BIT STRONGER WITH THE WAVE...AND DOES BRING SOME QPF FARTHER NORTH INTO LOWER MICHIGAN INITIALLY FOR TODAY...QUESTION REVOLVES AROUND THE DIFFUSE SURFACE FRONT JUST NORTH OF THE CWA. ETA/GFS HAVE BEEN TOO FAST DROPPING THIS FRONT SOUTHWARD...WITH THE 03Z RUC INITIALLY SLOWER AND BETTER. HOWEVER EVEN THE 06Z RUN JUMPS THE FRONT SOUTH QUICKLY THIS MORNING...WHICH SEEMS UNREASONABLE GIVEN THE MOIST AND UNSTABLE AIRMASS ACROSS THE STATE...ESPECIALLY ONCE THE SUN COMES UP. THEREFORE WILL HOLD ONTO POPS LONGER THAN MODELS WOULD INDICATE... KEEPING CHANCE NORTH/SCATTERED SOUTH THROUGH THE DAY. WITH SOME LINGERING INSTABILITY AND POTENTIAL FORCING WILL ALSO KEEP A CHANCE GOING ACROSS THE SOUTH THIS EVENING...BUT DRY OVERNIGHT. NOT MUCH IN THE WAY OF COLD ADVECTION WITH THIS FRONT. ALSO SKIES HAVE PRETTY MUCH CLEARED OUT OVERNIGHT BEHIND THE EARLIER ROUNDS OF STORMS. SOME AREAS ESPECIALLY ACROSS THE SOUTHERN CWA COULD GET SOME DECENT INSOLATION THIS MORNING...AND REACH TEMPERATURES IN THE UPPER 80S SIMILAR TO YESTERDAY. VISFOG SATELLITE SHOWS SOME CLOUDS TRYING TO DEVELOP...SO WILL START THE DAY OFF AS PARTLY SUNNY. ALTHOUGH WITH SOME CLEAR SPOTS...LIGHT WIND AND NEARLY SATURATED LOW LEVELS FROM RAIN YESTERDAY AFTERNOON AND OVERNIGHT...STILL COULD SEE SOME FOG THIS MORNING. NOW FOR WEDNESDAY. GFS HAS BEEN ALL OVER THE PLACE RECENTLY DUE TO POOR HANDLING OF CONVECTION...AND NOW ETA AND CANADIAN HAVE JOINED IN. IT IS EASY TO DISCOUNT THESE SOLUTIONS DUE TO GRIDSCALE FEEDBACK. WHAT IS SOMEWHAT TROUBLING IS THAT ALL OF THESE MODELS HAVE DEVELOPED SIMILAR PROBLEMS OVER THE SAME REGION...EVEN WITH DIFFERENT CONVECTIVE PARAMETERIZATIONS. ALSO OF INTEREST IS THE 02/12Z ECMWF. IT ALSO SHOWS A SIMILAR RADICAL CHANGE FROM ITS 02/00Z RUN...FROM A FRONT NEAR THE OHIO/TENNESSEE VALLEYS TO A SURFACE WAVE ALONG THE FRONT TRACKING NEAR CHICAGO. A QUICK LOOK AT THE 03/00Z RUN IS BASICALLY SIMILAR TO ITS 12Z RUN. THIS INDICATES THAT THE ECMWF PICKED UP ON A SYNOPTIC CHANGE 12 HOURS BEFORE THE ETA. UNFORTUNATELY IT IS HARD TO DIAGNOSE THE MODEL GIVEN OUR LIMITED DATA SET. HOWEVER IT DOES LOOK LIKE A REALISTIC TREND THAT BEARS ATTENTION. STRENGTHENING UPPER LEVEL JET/NORTHERN STREAM WAVE NEAR MANITOBA WILL DROP DOWN THROUGH THE REGION...HELPING THE CANADIAN LOW DROP SOUTHWARD THROUGH LATE WEEK...AND LOWERING HEIGHTS ACROSS THE REGION. INITIALLY THIS INCREASES THE MID-LEVEL CONFLUENCE ACROSS THE STATE...WHICH WOULD HELP KEEP PRECIP SOUTH OF THE STATE. HOWEVER THE UNSEASONABLE STRONG JET WILL ALSO SHIFT DOWNSTREAM...BRINGING SOME UPPER DIVERGENCE VICINITY OF THE RIGHT-REAR QUADRANT INTO PLAY. THIS MAY BE A REASONABLE SYNOPTIC FEATURE LEADING TO THE SURFACE WAVE DEVELOPMENT. 10KM TAQ-RUC AND NCAR MM5 ALSO SHOW SIMILAR SURFACE PATTERNS TO THE ECMWF. THESE MODELS TRY TO BRING QPF INTO THE SOUTHERN GREAT LAKES...LOOKING MORE LIKE OVERRUNNING PRECIP AS OPPOSED TO A CONVECTIVE COMPLEX...AND WEAKEN IT WITH TIME ON WEDNESDAY. WAS TEMPTED TO KEEP A DRY FORECAST ON WEDNESDAY... ALLOWING ANOTHER MODEL RUN TO CHECK FOR CONSISTENCY TO PREVENT A FLIP-FLOP. HOWEVER GIVEN SUPPORT FROM RUC/MM5 AND ECMWF...FEEL COMFORTABLE ADDING A CHANCE OF RAIN SHOWERS BACK FOR WEDNESDAY. WILL HOLD OFF ON THUNDER FOR NOW GIVEN OUR PLACEMENT NORTH OF THE LOW AND NATURE OF THE WEAKENING CONVECTION DURING THE DAY. IF OTHER 00Z SOLUTIONS PAN OUT...IT WOULD NOT BE UNREASONABLE TO INCREASE POPS OR ADD THUNDER...BUT FOR NOW A LOW CHANCE SEEMS LIKE THE BEST BET AS MAIN PRECIP SHOULD BECOME INCREASINGLY TIED TO THE SURFACE BOUNDARY AS WE DESTABILIZE DURING THE DAY. && .DTX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ BRAVENDER 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 1035 AM EDT TUE AUG 3 2004 .DISCUSSION... THE MAIN CONCERN WITH THIS UPDATE IS THE HIGH TEMPERATURES FOR THIS AFTERNOON. WATER VAPOR IMAGERY AND RUC/ETA SHOW A LOW OVER JAMES BAY AS PART OF A LONGWAVE TROUGH OVER EASTERN CANADA. A RIDGE STRETCHES FROM THE NORTHERN HIGH PLAINS THROUGH ALBERTA...WHILE ANOTHER LONGWAVE TROUGH IS OVER NORTHEAST GULF OF ALASKA. MODELS ARE SHOWING A WEAK SHORTWAVE ROTATING AROUND THE LOW AND EXTENDING FROM WEST CENTRAL QUEBEC ACROSS CENTRAL ONTARIO. SURFACE ANALYSIS INDICATE A COLD FRONT RUNNING FROM A LOW OVER SOUTHEAST QUEBEC THROUGH THE LOWER GREAT LAKES TO A NEBRASKA LOW. A MCS IS FIRING OVER CENTRAL SOUTH DAKOTA ALONG THIS FRONT AND ANOTHER IS OVER NORTHEAST MISSOURI. A DOME OF HIGH PRESSURE IS OVER CENTRAL CANADA SLOWLY EXPANDING INTO THE NORTHERN PLAINS AND UPPER GREAT LAKES. DRY AIR AND CLEAR SKIES WILL CONTINUE TO PUSH INTO THE AREA FROM CANADA WITH THE RIDGE. WINDS WILL REMAIN RELATIVELY LIGHT. THE MID LEVEL FLOW WILL DIRECT THE ENERGY FROM THE MCS TO THE SOUTHWEST OF THE FORECAST AREA THIS AFTERNOON. RUC SUGGEST THAT A VERY WEAK SHORTWAVE WILL SHIFT OVER THE FORECAST AREA BY LATE AFTERNOON. MEAN SURFACE-500MB RH WILL REMAIN LESS THAN 40 PERCENT...REALLY TOO DRY TO PRODUCE ANYTHING. THE INTERNATIONAL FALLS RAOBS THIS MORNING SUGGEST THAT THERE IS THE POSSIBILITY OF SOME CIRRUS OVERSPREADING THE AREA. THE TRAJECTORY FORECAST INDICATE THE AIR MASS OVER ONTARIO YESTERDAY WILL SHIFT OVER THE FORECAST AREA TODAY. GUIDANCE AND TRAJECTORY FORECAST FAVOR TEMPERATURES IN THE MID 70S. TEMPERATURES ARE ALREADY 3F TO 5F WARMER THAN GUIDANCE. PLAN TO UP THE HIGHS FOR TODAY BY A FEW DEGREE AS THE THIN CIRRUS AND LIGHT WINDS WILL CAUSE LESS MIXING AND MORE HEATING. ALONG THE LAKE SHORE CONDITIONS ARE SETTING UP FOR LAKE BREEZES. ONCE THE LAKE BREEZES SET IN...THOSE AREAS NEAR THE LAKE WILL SEE THE TEMPERATURES SLOWLY FALL. NOT MUCH CHANGE EXPECTED IN THE CONDITIONS SO THE REST OF THE FORECAST STILL LOOKS REASONABLE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1015 AM CDT TUE AUG 3 2004 .DISCUSSION... MAIN PART OF SD MCS SLIDING ESE..AND PARTS OF THIS SHOULD BRING RAIN INTO PARTS OF WEST CENTRAL AND FAR SOUTH. WILL UP SOME POPS IN FAR SOUTH CENTRAL AND SOUTHWEST CLOSEST TO LATEST RUC AND ETA FORECAST INSTABILITY AXIS AND 850 THETA E ADVECTION. THESE PARAMETERS FORCED FARTHER SOUTH THIS EVENING..LESSENING THE CHANCE OF PRECIP IN N CWA AND CHANCES OF THUNDER. && MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MBK/RAH mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE NORTH PLATTE NE 710 AM CDT TUE AUG 3 2004 ...MINOR UPDATE TO GRIDS AND ZONES FOR FOG AND LOW CLOUDS... .UPDATED... UPDATE TO REFLECT THE LOW CLOUDS AND FOG EXTENDING FROM EASTERN NEBRASKA INTO CHERRY COUNTY. LOW LEVEL EAST FLOW ASSENDING INTO THE AREA DID THE TRICK THIS MORNING BETWEEN 3AM AND 6AM. DEW POINTS IN THE 70S IN NORTH CENTRAL NEBRASKA AND RUC AND MESO ETA SOUNDINGS SHOW MOISTURE IN THAT AREA ERRODING AWAY AFTER 15Z AND THEN COMING UNCAPPED AROUND 20Z. WIND PROFILE THIS AFTERNOON NOT SHOWING A LOT OF STRENGTH BUT LOTS OF DIRECTIONAL SHEAR AND CAPE. PERHAPS THE ONE ELEMENT LIMITING SEVERE WEATHER POTENTIAL THIS AFTERNOON IS THE LACK OF A CAP ALLOWING CONVECTION TO SPREAD RATHER THAN REMAIN FOCUSED ALONG BOUNDARIES. UPPER AIR DATA WILL BE A LITTLE LATER THAN USUAL DUE TO A SECOND RELEASE THIS MORNING AT LBF. PREVIOUS DISCUSSION FOLLOWS... ...PRECIPITATION CHANCES AND TEMPERATURES IN THE NEAR TERM MAIN FOCUS... .DISCUSSION... MODELS IN FAIR AGREEMENT THROUGH 60 HRS...WITH GFS TENDING TOWARDS A BETTER SOLUTION TOWARDS PRECIPITATION PATTERN THROUGH PAST 24 HRS. CURRENTLY BOUNDARY OVER CENTRAL SOUTH DAKOTA WELL INDICATED BY LINE OF CONVECTION. TD'S REMAIN IN THE 70S EARLY THIS MORNING FROM VTN TO BBW AND EAST WITH EASTERLY SURFACE FLOW. HAVE KEPT SCHC GOING ALONG NE SD BORDER THIS MORNING WITH MENTION PATCHY FOG NORTH CENTRAL ZONES. TEMPERATURES LOWERED NOTHEAST WITH PROXIMITY OF FRONTAL BOUNDARY AND CLOUDS WITH EASTERLY UPSLOPE FLOW. THEN CHC NORTH CWA THIS AFTERNOON AND EARLY TONIGHT AS DESCENT WAVE DRIVES THROUGH NORTHWEST FLOW AND ABUNDANT LLMOISTURE AND TAPPING INTO TROPICAL MOISTURE STREAMING OVER ROCKIES AND SURFACE LOW DRIVES THROUGH THE AREA. WAVE DOES GOOD JOB OF BREAKING RIDGE DOWN WITH COOLER TEMPERATURES NOTHEAST TOMORROW. SOUTHERLY FLOW WED NIGHT CHC POPS WEST AS CONVECTION FIRING ALONG HIGH PLAINS MOVES EAST OVERNIGHT. NO ADJUSTMENTS OTHER THAN BLENDING MADE TO EXTENDED. WITH TEMPERATURES TAKING A DOWNWARD TREN IN SLOW UPPER AIR PATTERN WITH TROUGH DEEPENING OVER GREAT LAKES REGION. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ POWER ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1048 AM EDT TUE AUG 3 2004 .SHORT TERM (THIS AFT)... SURFACE ANALYSIS SHOWS HIGH PRESSURE RIDGE TO THE EAST OF FORECAST AREA WITH WEAK STATIONARY FRONT NORTH OF DAY AND CMH. SATELLITE IMAGERY SHOWING MAINLY CLEAR SKIES OVER FA. HOWEVER WITH TDS RISING TO 70 TO 72 THIS PM FAIR WEATHER CU WILL FORM...ESPECIALLY IN THE VICINITY OF BOUNDARY. ANY TSRA DEVELOPMENT WILL BE NEAR BOUNDARY AND WILL LIKELY WAIT UNTIL PEAK DAYTIME HEATING. BOTH 12Z RUC AND ETA SHOWING MODERATE INSTABILITY THIS PM WITH LITTLE IN THE WAY OF FORCING. BOTH INSTABILITY AND BOUNDARY MAKE IT PRUDENT FOR AT LEAST A SLIGHT CHANCE. IF ANYTHING DEVELOPS IT HAS THE POTENTIAL FOR BEING SEVERE (PULSE). UPDATE HAS BEEN SENT TO RESOLVE AFT SKY AND WIND WORDING. ALSO TO REMOVE SLIGHT CHANCE IN THE SOUTH. && .PREVIOUS DISCUSSION AVIATION (12Z-12Z)... WEAK HIGH PRESSURE REMAINS IN COMMAND. FOG AND MIST WILL DISSIPATE BY 13Z. SCATTERED CUMULUS WILL FORM BY MID MORNING POSSIBLY AIDED BY THE SHORT WAVE NEAR LAKE ERIE. MODELS INDICATE A RETENTION OF 850 MB MOISTURE TONIGHT SO I'M KEEPING SCATTERED CUMULUS AFTER 00Z. MID LEVEL CLOUDS MOVING IN TONIGHT SHOULD HINDER FOG DEVELOPMENT. && SHORT TERM (TODAY THROUGH THURSDAY)... FIRST CONCERN FOR THIS MORNING IS THE ISOLATED SHOWER ACTIVITY THAT HAS DEVELOPED ACROSS NORTHERN INDIANA IN THE PAST HOUR OR SO. THIS APPEARS TO BE ASSOCIATED WITH WEAK LOW LEVEL CONVERGENT BOUNDARY EXTENDING DOWN FROM MCS MOVING ACROSS SOUTHEASTERN MICHIGAN. 00Z ETA SEEMS TO HAVE A PRETTY GOOD HANDLE ON THIS...DROPPING CONVERGENT BOUNDARY DOWN INTO NORTHERN OHIO THROUGH THIS MORNING. THEREFORE...WILL BE TOUGH TO RULE OUT A STRAY SHOWER OR TWO ACROSS OUR FAR NORTH THIS MORNING. OTHERWISE...AIRMASS PROGGED TO DESTABILIZE FAIRLY WELL THROUGH THIS AFTERNOON AS TEMPS CLIMB INTO THE UPPER 80S AND DEWPOINTS CREEP INTO THE UPPER 60S. THIS YIELDS SURFACE BASED CAPES OF 2000-3000 J/KG FOR THIS AFTERNOON AND EARLY EVENING. NOT TOO MUCH IN THE WAY OF FORCING THROUGH THIS AFTERNOON BUT SINCE THERE DOES NOT APPEAR TO BE MUCH OF A CAP THIS AFTERNOON...WILL GENERALLY GO WITH A 20 POP FOR AN ISOLATED THUNDERSTORM OR TWO. THE ETA HAS BACKED OFF CONSIDERABLY ON S/W ENERGY THAT WAS SUPPOSED TO AFFECT THE AREA TONIGHT...NOW JUST SHOWING A WEAKENING VORT MAX MOVING IN FROM THE WEST IN THE 03Z TO 06Z TIME FRAME. THE GFS IS PERHAPS A LITTLE STRONGER THAN THE ETA BUT IT TOO HINTING AT A WEAKENING VORT AS IT APPROACHES FROM THE WEST THIS EVENING. AS A RESULT...WILL CONTINUE WITH POPS FOR TONIGHT BUT SCALE THINGS BACK A BIT. DIFFICULT TO GET A HANDLE ON THINGS FOR WEDNESDAY AS GFS AND ETA BOTH APPEAR TO BE TOO STRONG WITH SHORT WAVE AND ASSOCIATED SURFACE LOW FOR WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. THE ONE PROMISING THING IS THAT AT LEAST THEY ARE BOTH PRETTY CLOSE IN THEIR TIMING. BOTH ARE INDICATING FRONT PUSHING ACROSS OUR AREA DURING THE MORE FAVORABLE TIME OF DAY SO WILL BUMP UP POPS FOR WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT...BUT DUE TO MODEL UNCERTAINTY WITH STRENGTH WILL STILL KEEP POPS IN CHANCE CATEGORY. GIVEN THE FORECAST STRENGTH OF BOTH THE ETA AND GFS...IF EITHER OF THEM END UP BEING CLOSE TO RIGHT...WE WOULD LIKELY END UP WITH DECENT SEVERE WEATHER OUTBREAK AS ETA DEVELOPING A 50+ KT 8H JET ACROSS OUR AREA BY EARLY WEDNESDAY EVENING WITH FAVORABLE SHEAR PROFILES. ALSO...PWS ONCE AGAIN PROGGED TO EXCEED 2 INCHES SO HEAVY RAIN WOULD ALSO BE A POSSIBILITY. WITH SLOWER TREND...WILL HANG ON TO A LOW CHANCE ACROSS THE SOUTHEAST INTO EARLY THURSDAY. OTHERWISE...MUCH COOLER TEMPS EXPECTED FOR THURSDAY WITH GOOD CAA DEVELOPING BEHIND FRONT. JGL && LONG TERM (THURSDAY THROUGH MONDAY)... THERE IS A CONSENSUS AMONG THE LONG RANGE MODELS (GFS, ECMWF, UKMET) ON DEVELOPING AN UPR LVL LOW ACRS SERN CANADA AND NEW ENGLAND FROM THURSDAY THROUGH SUNDAY. AS OF NOW...OUR AREA IS FORECAST TO BE TO THE WEST OF THE UPR TROF AXIS...THUS...IN THE SUBSIDENCE AREA ALOFT. AS A RESULT...WILL KEEP FORECAST DRY THURSDAY THROUGH SUNDAY. MUCH COOLER AIR WILL ADVECT INTO THE LOWER GREAT LAKES AND OHIO VALLEY REGION FROM CANADA DURING THIS PERIOD. COLDEST HIGH TEMPS ARE EXPECTED TO OCCUR ON SATURDAY WITH THE COLDEST OVERNIGHT LOWS OCCURRING SATURDAY NIGHT. UPR LVL LOW WILL MOVE EAST ON SUNDAY...ALLOWING FOR RISING H5 HEIGHTS AND A GRADUAL WARMING TREND. NEXT CHC OF PCPN IS POISED FOR MONDAY NIGHT AS WAA AHEAD OF NEXT FRONTAL SYSTEM BRINGS A CHANCE OF SHOWERS AND THUNDERSTORMS. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. IN...NONE. KY...NONE. && $$ oh AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PITTSBURGH PA 1135 AM EDT TUE AUG 3 2004 .SHORT TERM (REST OF TODAY THROUGH WEDNESDAY NIGHT)... FOR THIS AFTERNOON AND EVENING...RECENT RUC MODEL RUNS SHOW INSTABILITY INCREASING WITH DIURNAL HEATING TO A CAPE OF NEAR 1000 J/KG AND LIFTED INDEX OF MINUS 3. RUC ALSO SHOWED SOME LOWLEVEL MOISTURE FLUX CONVERGENCE NEAR THE APPALACHIAN MOUNTAINS DUE TO THE CURRENT NORTHWEST WINDS OVER THE UPPER OHIO VALLEY AND NORTHEAST WINDS OVER VIRGINIA AROUND THE PERIPHERY OF HURRICANE ALEX CIRCULATION. APPALACHIANS WILL ALSO BE AN ELEVATED HEAT SOURCE. DELAYED NEXT CHANCE OF THUNDERSTORMS (POP 50%) UNTIL LATE WEDNESDAY...AS NEW ETA MODEL RUN CONTINUES TO SHOW THE LOW PRESSURE SYSTEM FROM THE DAKOTAS NOT BRINGING SHOWERS AND THUNDERSTORMS UNTIL WEDNESDAY NIGHT. 06Z GFS WAS A COUPLE HOURS FASTER WITH THE ONSET. WILL REVIEW THESE MODELS CLOSER FOR 4PM FORECAST CYCLE...AS MAY HAVE TO UP PROBABILITY OF PRECIPITATION (POP) TO LIKELY RANGE (60-70%). ALSO SPC HAS OUTLOOKED THE UPPER OHIO VALLEY WITH A SLIGHT RISK OF SEVERE THUNDERSTORMS THEN. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 303 AM EDT TUE AUG 3 2004 AVIATION... PATCHY FOG ACROSS THE AREA THIS MORNING WILL BURN OFF A FEW HOURS AFTER SUNRISE. MVFR VSBY THIS MORNING IN GENERAL WITH SOME SPOTS IFR IN BR. A COLD FRONT MOVING THROUGH THE AREA WILL BRING SCATTERED SHOWERS AND THUNDERSTORMS TODAY. SHOWERS/TSTMS MORE NUMEROUS NORTH. SHORT TERM (TODAY THROUGH WEDNESDAY)... SCATTERED SHOWERS AND THUNDERSTORMS TODAY AND THIS EVENING AS A COLD FRONT MOVES THROUGH THE AREA. SLIGHTLY HIGHER POPS NORTH. DURING THE DAY ON WEDNESDAY PCPN MOVES BACK INTO FA AS LOW PRESSURE SYSTEM APPROACHES FROM THE WEST. LONG TERM (WEDNESDAY NIGHT THROUGH MONDAY)... SECOND HALF OF WEEK IN UPPER NORTHWEST FLOW EXPECT BELOW NORMAL TEMPS AND GENERALLY DRY. GFS CONTINUES TO HINT AT CHC POPS FOR FRIDAY IN WRAP AROUND. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ SHORT TERM...11 pa AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 1000 AM MDT TUE AUG 3 2004 .DISCUSSION...CURRENT SFC ANALYSIS SHOWS STATIONARY BOUNDARY WELL INTO NE AND EXTENDING INTO N CTRL WY. PLENTY OF LOW CLOUDS AROUND TO THE N OF THIS BOUNDARY. 12Z RUC BUFKIT SOUNDINGS SHOW LIMITED INSTABILITY OVER MOST OF THE CWA...THE EXCEPTION BEING AROUND 5 S CTRL COUNTIES FOR THIS AFTN. NOT VERY CONFIDENT ABOUT THE SLT RISK AREA NOW...ESP ACROSS NRN ZNS AND WL WAIT TO SEE WHAT NEW SPC OUTLOOK HAS BEFORE TAKING OUT SVR WORDING FROM ZONES. IT DOES STILL LOOK LIKE A GOOD CHANCE FOR SHOWERS AND TSMS OVER AREAS N OF I-90 IN SD THOUGH WITH NICE S/W MVG OUT OF MT. TEMPS WL ALSO BE TRICKY WITH THE LOW CLOUDS AROUND. TEMPS HAVE NOT MOVED MUCH OVER THE LAST COUPLE OF HOURS AND MANY AREAS MAY STRUGGLE TO GET OUT OF THE 70S. HAVE UPDATED ZNS TO TAKE OUT MRNG WORDING AND LWR TEMPS A FEW DEG. && .UNR...WATCHES/WARNINGS/ADVISORIES... .SD...NONE. .WY...NONE. $$ JMG sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 405 PM CDT TUE AUG 3 2004 .DISCUSSION... MAIN CONCERNS ARE PRECIPITATION CHANCES TONIGHT AND OVER THE WEEKEND. UPPER SYSTEM MOVING THROUGH THIS EVENING PROVIDING COOLING ALOFT WITH SOME POTENTIAL FOR SEVERE WEATHER ALONG SURFACE BOUNDARY. CAPPING STILL IN PLACE AS NOTED BY HOURLY SATELLITE TEMPERATURES...HOWEVER NEW RUCII SHOWING COOLING ALOFT LATER THIS EVENING IN CONJUNCTION WITH FRONTAL BOUNDARY. LATER 18Z MODEL RUNS SHOWING BOUNDARY AND SUPPORT ALOFT MOVING THROUGH BY DAWN...HAVE KEPT MINIMAL POPS IN THE EARLY FORENOON WEDNESDAY...BUT THAT MAY BE OVERDONE IF 18Z RUNS ARE CORRECT. WOULD SUSPECT LOTS OF CU/TCU ON WEDNESDAY WITH RESIDUAL SURFACE MOISTURE AND STEEPER LAPSE RATES. HOWEVER, CHANCES FOR PRECIPITATION MINIMAL WITH LITTLE OR NO OTHER SUPPORT FOR CONVECTIVE RAIN WITH BOUNDARY WELL TO OUR SOUTHEAST. BEYOND TONIGHT AND THROUGH SATURDAY...ONLY FORECASTING CHALLENGE IS DETERMINING HOW MUCH COOLER TO CONSIDER. MODELS CONSISTENT IN NORTHWEST FLOW CLOUDS WITH SOME TSTMS POSSIBLE OVER THE HIGH PLAINS. EASTERLY SURFACE FLOW OUR AREA. CONSIDERABLY BELOW CLIMO INTO SATURDAY WITH THIS SCENARIO AND OCCASIONAL CLOUDS. OVER THE WEEKEND...PREFER TO LEAN TOWARD THE EURO MODEL IN FRONTAL POSITIONING AND PRECIPITATION CHANCES. ALREADY HAD LOW POPS IN FOR SATURDAY NIGHT. HAVE ADDED THEM FOR SUNDAY AND SUNDAY NIGHT. NORMALLY VERY CONSERVATIVE EURO MODEL HAS DONE A GOOD JOB SO FAR THIS SUMMER INCLUDING MOVING FRONTS THROUGH AN OTHERWISE VERY WARM MIDSUMMER ATMOSPHERE. ONCE AGAIN EURO DOES THIS AND WILL FOLLOW ITS LEAD. ANOTHER TREND THIS SUMMER HAS BEEN FOR FRONTS TO ACTUALLY MOVE THROUGH A LITTLE QUICKER THAN ONE MIGHT THINK FOR THIS TIME OF YEAR. THUS, REASONING FOR NOT DROPPING PRECIPITATION ON SATURDAY NIGHT. GFS MAINTAINS PRECIPITATION TOO LONG IN MY OPINION INTO NEXT WEEK...MAINLY BECAUSE IT DOES NOT DEVELOP ENOUGH AMPLITUDE IN RIDGE TO OUR WEST. NEWEST UK MODEL ALSO HAS HIGH AMPLITUDE RIDGE BUILDING TO OUR WEST NEXT WEEK WITH LITTLE CHANCE FOR PRECIPITATION. WOULD SUSPECT TEMPERATURES TO GRADUALLY RESPOND BY END OF FORECAST PERIOD...OR JUST BEYOND...TO ABOVE CLIMO LEVELS AS RIDGE GRADUALLY UNDERGOES THIS AMPLIFICATION. && .TOP...WATCHES/WARNINGS/ADVISORIES... HEAT ADVISORY UNTIL 8 PM GENERALLY EAST OF A LINE FROM ABILENE TO MARYSVILLE. && ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 330 PM EDT TUE AUG 3 2004 .DISCUSSION... A VERY CHALLENGING FORECAST THIS AFTERNOON WITH CONVECTIVE POTENTIAL LOOMING AND WE ARE MONITORING FLOODING POSSIBILITIES ON WEDNESDAY. LATEST UPPER AIR/H2O VAPOR ANALYSIS SHOWS A VERY ACTIVE UNSEASONABLE PATTERN IN PLACE WITH FAST WESTERLY FLOW RIDING ALONG THE U.S./CANADIAN BORDER (100KT 300MB JET). LEAD SHORT WAVE TROF WAS PROGRESSING NORTHEAST ACROSS MONTANA/WYOMING WITH ANOTHER WAVE PROGRESSING SOUTHEAST ACROSS LAKE WINNIPEG. A COUPLE OF CONVECTIVE COMPLEXES WERE IN PROGRESS AT 18Z WITH THE MORE POTENT ONE ENTERING INTO SOUTHERN MINNESOTA/NORTHERN IOWA. AT THE SURFACE, QS-BOUNDARY WAS DRAPED ACROSS SOUTHERN LOWER MICHIGAN (SOUTH OF I69) WHICH WAS ATTACHED TO LOW PRESSURE ACROSS NEBRASKA/KANSAS. MEANWHILE, STRONG HIGH PRESSURE (1023MB) WAS PUSHING SOUTH FROM NORTH CENTRAL CANADA. THE PRESSURE GRADIENT FORCE WILL LIKELY LEAD TO UPSLOPE ACROSS MONTANA/WYOMING AND COMBINING WITH THE AFOREMENTIONED UPPER LEVEL FEATURES, WE SHOULD SEE ANOTHER COMPLEX OF STORMS DEVELOP SOON. THIS DEVELOPMENT WILL BE THE MAIN KEY TO THIS FORECAST WITH MODELS HANDLING THIS QUITE DIFFERENTLY WITH CONSENSUS LEANING TOWARD A WET DAY FOR THE SOUTHERN HALF OF THE CWA (FOR NOW). AS WITH THE CONVECTIVE POTENTIAL TONIGHT, THIS FRONT WILL LIKELY STALL ACROSS THE MI/IN/OH STATE BORDER THIS EVENING AND BOUNCE AROUND OVERNIGHT. HARD TO SEE ANY MID LEVEL WAVE TO ASSIST WITH ADDITIONAL LIFT, BUT AS WAS THE CASE LAST NIGHT WITH CAPES AROUND 2000 J/KG THIS AFTERNOON AND A SLOW DECREASE IN TEMPS, WE SHOULD BE ABLE TO HOLD ONTO ENOUGH INSTABILITY SOUTH OF M59 FOR THE CHANCE OF THUNDERSTORMS TONIGHT. FURTHER NORTH, FLOW WILL BECOME MORE NORTHERLY WITH TIME TO ASSIST WITH THE STABILIZATION TO PRECLUDE THE MENTION OF PRECIP AT THIS TIME. TEMPS WILL BE TRICKY AS THE PLACEMENT OF THIS FRONT AND INCREASING HIGH/MID LEVEL MOISTURE FROM UPSTREAM CONVECTION WILL PLACE A GOOD GRADIENT ACROSS THE CWA. WITH THIS INCREASING NORTHERLY FLOW, MARINE INFLUENCE WILL BE FELT TO OUR NORTH AND ESPECIALLY ALONG THE LAKE SHORE...FURTHER SOUTH WITH A WARMER AFTERNOON AND STILL SOME HIGH DEWPOINTS WE WILL HOLD ONTO THE MIDDLE 60S FOR OVERNIGHT LOWS HERE. THEN COMES THE CHALLENGE FOR WEDNESDAY. OUT OF ALL OF THE AVAILABLE NUMERICAL GUIDANCE (ALL RUC VERSIONS, ETA, NGM, GFS, UKMET), THE NGM IS THE FURTHEST SOUTH WITH THE GFS THE FURTHEST NORTH WITH THE PLACEMENT OF SURFACE LOW AND EXPECTED QPF. AS CANADIAN WAVE BECOMES MORE STRUNG OUT AND PUSHES SOUTH INTO THE UPPER LAKES, BAROCLINICITY INCREASES AND THE MID LEVEL FLOW BECOMES MORE ZONAL. THIS SHOULD FORCE ANY UPSTREAM CONVECTION TO RIDE EAST-WEST WHICH IS ALONG AND NORTH OF THE QS-BOUNDARY. IN ADDITION, WE BECOME MORE UNDER THE INFLUENCE OF THE ENTRANCE REGION OF THE 100+KT JET STREAMING NORTHEAST OF LAKE HURON. INSTABILITY AND SHEAR SOUTH OF THIS FRONT IS FORECAST TO BE VERY IMPRESSIVE WHICH IS ANOTHER KEY/PROBLEM TO THIS FORECAST. PWATS CLIMB OVER 2" SOUTH OF THE ARB-DTW LINE WITH INCREASING FGEN FORCING AT THE 850-700MB LAYER. THE ETA POINTS TOWARD LOCATIONS SOUTH OF M59 FOR HEAVY RAINFALL WITH THE GFS/TAQ RUC AND WRF RUC ALONG WITH THE GFS IS FURTHER NORTH. EITHER WAY, RAINFALL AMOUNTS IN THE QPF FIELDS ARE ALARMING WITH TOTALS BETWEEN 2-4" BY THE TIME THIS IS ALL DONE! DPROG/DT FAVORS THE GFS ALTHOUGH SURFACE WAVE INTENSITY IS LIKELY CONVECTIVELY INDUCED WHICH IS SEEN AT ALL LEVELS IN THE MODEL. AT THIS TIME, WE WILL HAVE LIKELY POPS FOR LOCATIONS SOUTH OF M59 WITH A CHANCE NORTH (LOWEST POPS FOR BAY-MIDLAND COUNTIES). THERE IS A POTENTIAL FOR A LARGE BUST/CHANGE TO THIS FORECAST AND WE WILL HOLD OFF ON ANY FLOOD HEADLINES FOR NOW. IF CONVECTION FIRES SOUTH OF THE BOUNDARY, AVAILABLE MOISTURE WILL BE REDUCED. TIMING OF PRECIP WILL PROBABLY BE AFTER 15Z. IT APPEARS THE UPPER WAVES WANT TO PHASE OVER THE GREAT LAKES WITH SHOWER ACTIVITY DECREASING FROM WEST TO EAST DURING THE EVENING. FAIRLY TIGHT PRESSURE GRADIENT EVOLVES ACROSS THE CWA AS COOLER AND DRIER AIR FILTERS SOUTH OVERNIGHT. THEN AN UNSEASONABLY IMPRESSIVE EAST COAST TROF SETS UP WITH COLD CANADIAN HIGH BUILDING SOUTH INTO THE UPPER PLAINS THEN ACROSS THE GREAT LAKES INTO THE WEEKEND. WE WILL BE QUITE COLD WITH HIGHS HOLDING INTO THE LOWER 70S WITH INTERMITTENT CLOUD COVER UNTIL THE WEEKEND. WARM ADVECTION IS HOLDING UP IN THE 12Z GFS FOR EARLY NEXT WEEK AND MODEL CONSENSUS BRINGS ANOTHER FRONT INTO THE REGION FOR EARLY NEXT WITH A CHANCE FOR ADDITIONAL CONVECTION. THANKS FOR THE COLLABORATION SURROUNDING WFO/S, HPC AND SPC! && .HYDROLOGY... HURON RIVER AT HAMBURG IS ALREADY RUNNING HIGH AT 6.43 FEET AND RIVERS ARE BOUNCING UP/DOWN WITH RECENT RAINFALL. RUNNING LOCAL MODELS ON EXPECTED RAINFALL, WE COULD SEE SOME QUICK RISES. AGAIN, WE WILL AWAIT FOR ADDITIONAL RUNS AND UPPER AIR DATA BEFORE MAKING ANY HEADLINE DECISIONS. && .DTX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ BGM 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 322 PM EDT TUE AUG 3 2004 .DISCUSSION... WATER VAPOR IMAGERY AND 500MB ANALYSIS SHOWS A RIDGE BUILDING INTO THE CANADIAN ROCKIES...AN UPPER TROUGH OVER JAMES BAY AND WNW FLOW ACROSS THE UPPER GREAT LAKES. A SHORTWAVE IN THE PLAINS IS KICKING OFF SEVERE CONVECTION JUST NORTH OF A SFC BOUNDARY IN SWRN MN/NWRN IA...BUT AS THIS BOUNDARY IS WELL TO OUR SOUTH ACROSS THE LOWER GREAT LAKES...THE ACTIVITY WILL REMAIN WELL TO OUR SOUTH TONIGHT (TRACKING TO THE ESE). RADAR DOES SHOW SOME SHRA DEVELOPING FROM CENTRAL WI TO WEST OF DLH. OTHERWISE THERE IS ONLY SOME BENIGN CU AND CIRRUS BLOW OFF OVER THE U P. ONLY IMPACT FROM THE CONVECTION CURRENTLY TO OUR SOUTHWEST WILL BE HIGHER CLOUD. THOUGH DIURNAL CU WILL FADE WITH LOSS OF DAYTIME HEATING...HIGH CLOUD IN THE SOUTH SHOULD HELP TO KEEP TEMPS UP A BIT DESPITE LIGHT WINDS AND A DRYING AMS. THUS HAVE SIDED A BIT ABOVE GUIDANCE FOR LOWS TONIGHT...ESPECIALLY IN THE SOUTH. WITH THE WNW FLOW...NORTHERN PARTS SHOULD BE MOSTLY CLEAR TONIGHT. SHRA DEVELOPING IN CENTRAL WI LINE UP WELL WITH A BAND OF H8 THETA-E ADVECTION AHEAD OF THE MAIN SHORTWAVE. RUC/ETA SHOW LOWER VALUES OF THETA-E ALREADY ADVECTING INTO THE U P FROM THE NNW (H8 DEWPTS OF 5C/1C AT INL/WPL THIS MORNING...COMPARED TO 11C/13C AT GRB/MPX)...SO BELIEVE THE SHOWERS WILL NOT MAKE IT THIS FAR NORTH. GFS CONTINUES TO BE OVERDONE IN THIS REGARD. FLOW BECOMES MUCH MORE AMPLIFIED WED-FRI AS A RIDGE CONTINUES TO BUILD OUT WEST AND A DEEP UPPER TROUGH DROPS ACROSS THE EASTERN CONUS. CONFLUENT NLY FLOW ALF WILL ALLOW OUR WEATHER TO BE DICTATED BY A DRY/COOL SFC RIDGE...IMPRESSIVELY SO FOR EARLY AUGUST AS WE TAP INTO AIR FROM THE CANADIAN ARCTIC. WILL HAVE A PERIOD OF BELOW NORMAL TEMPS WED-FRI...WITH HIGHS ANYWHERE FROM THE 60S TO LOWER 70S AND LOWS GENERALLY IN THE 40S...WITH THE COOLEST DAY APPEARING TO BE THU. THOUGH WE WILL BE WITHIN A FEW DEGREES OF RECORD LOWS...THE RIDGE AXIS WILL REMAIN TO OUR WEST...AND THE PRES GRADIENT/WIND SHOULD KEEP OVERNIGHT LOWS FROM FALLING TO RECORD LEVELS. EVEN THEN...THE WESTERN HIGHER TERRAIN SHOULD DROP TO AROUND 40F BY FRIDAY MORNING. BRRR. IN THE EXTENDED (SAT-TUE)...THERE IS PLENTY OF VARIABILITY REGARDING THE BREAKDOWN OF THE WESTERN RIDGE AND HOW/WHEN A SHORTWAVE WILL DROP THROUGH THE UPPER GREAT LAKES. AFTER A DRY AND SOMEWHAT WARMER PERIOD SAT INTO SUN (AS RETURN FLOW KICKS IN)...WILL KEEP WITH A COMPROMISE AMONG MODELS AND INTRODUCE A CHANCE OF TSRA SUN NIGHT THROUGH MON. AGAIN...TIMING AT THIS POINT IS UNCERTAIN. LOOKS AS IF THE WARMING WILL BE SHORT-LIVED AS ANOTHER DOSE OF FALL-LIKE TEMPERATURES ARE IN STORE FOR US BY MIDWEEK...POSSIBLY BY TUE...AS A STRONG COLD FRONT PUSHES THROUGH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ JKL mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 340 PM CDT TUE AUG 3 2004 .DISCUSSION... THUNDERSTORM CHANCES OVERNIGHT ARE THE MAIN CONCERN IN THE SHORT TERM. THE HEAT IS ALREADY TAKEN CARE OF...AS THE HEAT ADVISORY RUNS UNTIL 8 PM. AFTER THAT WE ARE WAITING FOR SOME RAIN TO FINISH COOLING US OFF. COMPLEX OF STORMS CURRENTLY MOVING ACROSS IOWA AND SOUTHERN MN SHOULD CONTINUE MOVING EAST. IT SHOULD DROP SOUTH EVENTUALLY...BUT AND SHOULD BE WELL EAST OF US WHEN IT DOES SO. THE REMAINDER OF THE RAIN CHANCES WILL BE FROM TWO SEPARATE AREAS OF DEVELOPMENT. ETA AND GFS BOTH ADVERTISE A COMPLEX OF STORMS ROLLING OUT OF EASTERN NEBRASKA AND DROPPING SOUTH INTO NORTHWEST MO. CURRENT RADAR INDICATIONS ARE NO WHERE NEAR HAVING THIS HAPPEN...WITH MODELS SHOWING NORTHWEST MO UNDER THE GUN AROUND 00Z. 12Z TOP SOUNDING HAD H7 TEMPS AT +14...SO SOUTHWARD MOVEMENT OF STORMS WILL BE TOUGH UNTIL THE FRONT ARRIVES. MODELS ARE ALSO CONSISTENT IN HAVING SOME SPOTTY DEVELOPMENT ALONG THE FRONT WHICH SHOULD ARRIVE SOMETIME AFTER 06Z. THERE IS DECENT SHEAR AND INSTABILITY ASSOCIATED WITH THE FRONT...SO ISOLATED SEVERE OVERNIGHT IS ALSO POSSIBLE. HAVE HIGHER POPS NORTH OF HWY36 THIS EVENING FOR ACTIVITY DROPPING DOWN FROM IOWA...AND CHANCE ACROSS THE REST OF THE AREA FOR STORMS WITH THE FRONT. WILL KEEP SOME POPS IN THE EAST FOR POSSIBLE WED MORNING ONGOING ACTIVITY. THE REST OF THE DAY SHOULD BE IN THE 80S. MODELS ARE SHOWING SOME STRATUS COMING DOWN BEHIND THE FRONT...SO CLOUD DECK SHOULD ALSO KEEP TEMPS IN CHECK. A NORTHWEST FLOW REGIME WILL CONTINUE TO PREVAIL ACROSS THE REGION FROM FRIDAY INTO THE WEEKEND...AS THE TROUGH OVER THE EASTERN CONUS AMPLIFIES AND SUPPRESSES THE WESTERN RIDGE. THE USUAL UNCERTAINTIES WITH THIS PATTERN WILL MAKE POP DETERMINATION DIFFICULT...BUT ANTICIPATE THE BEST OPPORTUNITY FOR SHOWERS AND THUNDERSTORMS TO ARRIVE AT THE END OF THE WEEKEND. MEDIUM RANGE MODEL SOLUTIONS KEY IN ON A STRONGER SHORTWAVE TROUGH AND ASSOCIATED COLD FRONTAL PASSAGE ON SUNDAY AND MONDAY...ALTHOUGH LARGE DIFFERENCES REGARDING ITS PATH ARE PRESENT. THE GFS BRINGS THE LOW SOUTH ACROSS THE UPPER AND CENTRAL MISSISSIPPI VALLEY REGIONS...WHILE THE ECMWF FAVORS A MORE NORTHERLY TRACK ACROSS THE GREAT LAKES. EITHER WAY...THINK LOW CHANCE POPS ARE WARRANTED AT THIS POINT. HAVE HIGHLIGHTED MONDAY WITH 30 POPS ASSOCIATED WITH THE FROPA...WITH 20 POPS DURING ADJACENT PERIODS. NO BIG CHANGES WERE MADE WITH RESPECT TO TEMPERATURES...WITH READINGS EXPECTED TO BE NEAR TO OR BELOW NORMAL THROUGH MOST OF THE EXTENDED PERIOD. LVQ/LS && .PREV DISCUSSION... 400 AM TUE... I AM EXPECTING A MARKED INCREASE IN CONVECTION IN SOUTHERN IOWA DURING THE NEXT COUPLE OF HOURS. LIKE YESTERDAY MORNING, THE 310K ISENTROPIC SURFACE (ANALYZED BY THE RUC) SEEMS TO BE TOOL MOST USEFUL FOR DETERMINING LIFT FOR CONVECTIVE DEVELOPMENT. THE FOG CHANNEL SHOWS THE DEVELOPMENT OF A BAND OF STRATUS OVER SOUTHWEST IOWA DOWN THROUGH MARYVILLE, MISSOURI. THIS NARROW STRIP OF CLOUDS IS LIKELY THE DEMARCATION OF THE EDGE OF THE CAP. SHALLOW MOISTURE IS LIKELY TRAPPED BELOW THE CAP. SO FOR THIS MORNING, I HAVE INCLUDED 30 PERCENT CHANCES FOR THUNDER EAST OF A LINE FROM BETHANY TO MOBERLY. I MAY NEED TO INCREASE PROBABILITIES IF CONVECTION INCREASES LIKE IT HAS THE LAST FEW MORNINGS, BUT 00Z RAOBS INDICATE THAT THE MOISTURE LAYER IS MORE SHALLOW THAN RECENT DAYS, SO THUNDER MAY BE A BIT MORE SPOTTY. DEWPOINTS REACHED OPPRESSIVE LEVELS YESTERDAY IN EASTERN KANSAS AND WESTERN MISSOURI. UPPER 70 DEWPOINTS PUSHED HEAT INDICES WELL ABOVE 105 DEGREES LATE IN THE DAY IN KANSAS CITY AND SAINT JOSEPH. DEWPOINTS HAVE ONLY DROPPED A FEW DEGREES OVERNIGHT. YESTERDAY A LIGHT SOUTH WIND, STRONG EVAPOTRANSPIRATION, SIGNIFICANT CAPPING, AND MOISTURE POOLING ALONG A STATIONARY BOUNDARY IN NORTHERN MISSOURI CONTRIBUTED TO THE STAGGERING LEVELS OF HUMIDITY. TODAY, I AM BANKING ON MORE MIXING THIS AFTERNOON TO CUT DEWPOINTS DOWN A FEW DEGREES IN THE KANSAS CITY AND SAINT JOSEPH AREAS. AFTERNOON DEWPOINTS IN EXCESS OF 75 DEGREES ARE LIKELY FROM MARYVILLE TO CHILLICOTHE, THOUGH WHERE WINDS WILL BE LIGHTER NEAR THE STATIONARY FRONT. TEMPERATURES ACROSS THE REGION SHOULD BE TWO OR THREE DEGREES WARMER TODAY WITH COMPRESSIONAL WARMING AS THE FRONT TO OUR NORTHWEST STRENGTHENS. HEAT ADVISORY CRITERIA (HEAT INDEX GREATER THAN 105 DEGREES FOR 3 HOURS) SHOULD BE MET IN EASTERN KANSAS AND A SIGNIFICANT CHUNK OF NORTHERN MISSOURI. FOR NOW I WILL KEEP BETHANY, KIRKSVILLE, MACON, AND MOBERLY OUT OF THE ADVISORY SINCE CLOUDS FROM CONVECTION IN IOWA THIS MORNING WILL SLOW HEATING. HEAT WAVES HAVE BEEN VERY SHORT LIVED THIS SUMMER, AND OUR CURRENT ONE WILL BE NO EXCEPTION. WATER VAPOR IMAGERY THIS MORNING SHOWS THE LONGWAVE PATTERN RETURNING TO OUR PREDOMINANT FLOW FOR THIS SUMMER. A DEEP TROUGH OFF THE NORTHWEST COAST, RIDGE OVER THE NORTHERN ROCKIES, AND DOWNSTREAM TROUGHING OVER CENTRAL CANADA. THIS SET UP HAS DUMPED COOLER THAN AVERAGE TEMPERATURES INTO THE CENTRAL UNITED STATES TIME AND AGAIN THIS SUMMER, AND IS POISED TO DO IT AGAIN. THE LEADING EDGE OF THE COOLER AIR WILL ARRIVE TOMORROW. THE GFS CONTINUES TO TREND COOLER WITH A HIGHLY AMPLIFIED EASTERN U.S. TROUGH BY THE END OF THE WEEK. I'VE LOWERED TEMPERATURES AGAIN FOR THE SECOND HALF OF THE WEEK, AND THE DAY SHIFT MAY NEED TO DROP TEMPERATURES EVEN MORE FOR THURSDAY THROUGH SATURDAY. KOCH && .EAX WATCHES/WARNINGS/ADVISORIES... KS...HEAT ADVISORY FROM 400 AM CDT TUESDAY UNTIL 800 PM CDT TUESDAY FOR ZONES KSZ025...KSZ057...KSZ060...KSZ102>105. MO...HEAT ADVISORY FROM 400 AM CDT TUESDAY UNTIL 800 PM CDT TUESDAY FOR ZONES MOZ001>004...MOZ011>014...MOZ020>023...MOZ028>032... MOZ037>040...MOZ043>046...MOZ053>054. && $$ WFOEAX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 404 PM EDT TUE AUG 3 2004 .SHORT TERM (TONIGHT THROUGH THURSDAY NIGHT)... CAPPED ATMOSPHERE WILL REMAIN OVER FCST AREA UNTIL COLD FRONT MOVES THROUGH FCST AREA ON WEDNESDAY/WED NIGHT. HAVE DECREASED THE CHANCE OF THUNDERSTORMS IN THE SOUTHEAST AS THIS CAP SHOULD REMAIN IN PLACE WITH WAA AHEAD OF THE FRONT. STILL HAVE SLIGHT CHANCE MENTIONED HERE IN THE AFTERNOON IN CASE A BOUNDARY DEVELOPS AND OUTPACES THE FRONT DURING THE DAY. H8 +20 AIR AHEAD OF FRONT...STRENGTH OF SFC LOW...10 C DIFFERENCE IN TEMPERATURE BEHIND LOW...STRONG 2500+ CAPES ALL POINT TO POSSIBILITY OF SVR WX LATER TOMORROW INTO THE EVENING HOURS. PROBLEM HERE IS THE PLACEMENT OF FEATURES AND TIMING OF SYSTEM. CAPES DECREASE IN THE AFTERNOON AS CLOUD COVER CUTS OFF STRONG DIURNAL HEATING...BUT HELICITIES INCREASE DRAMATICALLY WITH APPROACH OF FRONT. GFS IS FURTHER N WITH THE CENTER OF THE SFC LOW BUT MOST MODELS ARE IN AGREEMENT WITH THE FRONTAL PASSAGE FROM 0 TO 6Z THURSDAY. HAVE INCREASED CHANCE OF STORMS TO AT LEAST LIKELY FOR ENTIRE CWA DURING THIS PERIOD...SOME SPOTS CATEGORICAL WHERE TIMING WASN'T AS MUCH OF AN ISSUE. WITH REGARDS TO TEMPS...WAS INITIALLY GOING TO RAISE LOWS TONIGHT TO AROUND 70/LOW 70S ACROSS THE BOARD BUT DECIDED TO KEEP PREVIOUS FCST LOWS AS THIS WOULD'VE BEEN A GOOD BIT WARMER THAN SURROUNDING FO'S. TEMPS ON WED SHOW AN EARLY HIGH AROUND 18Z IN MOST PLACES WITH THINGS COOLING OFF IN THE AFTERNOON NW-SE IN RESPONSE TO THE FRONT. BELIEVE THAT THE COLD AIR BEHIND THIS SYSTEM WILL DISALLOW ANY CLOUD COVER AT NIGHT BUT PERMIT A GOOD BIT OF SHALLOW CU DURING THE EARLY AFTERNOON HOURS THURS. THURS...FRI...AND INTO THE WEEKEND COULD SEE RECORD COLD TEMPS. AM NOT SO CONFIDENT WITH PUTTING THIS IN FCST ATTM WITH THE GFS BEING COLDEST MODEL AND SIG COOLER THAN OTHERS. && .LONG TERM (FRIDAY THROUGH TUESDAY)... LONG RANGE MODELS CONTINUE TO BE IN DECENT AGREEMENT WITH RESPECT TO THE SYNOPTIC SCALE PATTERN. COLD UPR LVL LOW WILL BE LOCATED NEAR LAKE ONTARIO BY 12Z FRIDAY. RESIDUAL 850 MB MOISTURE...CAA AND DAYTIME HEATING WILL RESULT IN CUMULUS DEVELOPMENT ON FRIDAY. TEMPS WILL BE UNSEASONABLY COLD WITH HIGHS IN THE LOWER 70S EXPECTED. THE UPR LEVEL LOW WILL SLOWLY PUSH OFF TO THE NE ON SATURDAY ...CONTINUING THIS TREND INTO SUNDAY. DRY WX IS EXPECTED OVER THE WEEKEND AS THE REGION REMAINS UNDER A WEST TO NORTHWEST FLOW ALOFT. 500 MB HEIGHTS AS WELL AS 850 MB TEMPS WILL GRADUALLY RISE THROUGH THE WEEKEND...RESULTING IN A WARMING TREND. THE NEXT WX SYSTEM TO AFFECT THE REGION WILL BE AN UPR LVL S/WV AND ASSOCIATED COLD FRONT. THE FRONT WILL APPROACH THE LOWER GREAT LAKES ON MONDAY. WARM...MOIST AIR OUT AHEAD OF THE FRONT WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS ON MONDAY. THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE INTO TUESDAY AS THE FRONT TRAVERSES THE REGION. && .PREVIOUS DISCUSSION... AVIATION (18Z-18Z) SURFACE ANALYSIS SHOWS WEAK STATIONARY FRONT ACROSS NORTHERN OHIO. LATEST SATELLITE IMAGERY SHOWS CU FIELD MORE EXTENSIVE NEAR AND SOUTH OF THE FRONT WHERE TDS ARE AROUND 70. 12Z ETA/RUC SHOW WEAK FORCING LATTER THIS AFTERNOON ALONG WITH MODERATE INSTABILITY. 12Z RUC SHOWS CAP WILL BE IN PLACE THIS AFTERNOON. ALL THIS BEING SAID WOULD NOT BE SURPRISED TO SEE ISOLATED TSRA NORTH OF DAY AND CVG. ONCE DAYTIME HEATING IS LOSS THEN CU WILL DISSIPATE. WITH LIGHT WINDS AND NEARLY CLEAR SKIES THINK FOG WILL BE AN ISSUE AGAIN TONIGHT. CVG..DAY..ILN..CMH SHOULD ALL BE MVFR WITH LUK DROPPING INTO LIFR. DAY AND CMH STARTED MVFR A BIT EARLIER WITH TD POOLING AND POSSIBLE EVE CONVECTION TO THE NORTH OF TAF SITES. AFTER 12Z ETA/GFS SHOWING CONVECTION ADVECTING INTO DAY/CMH/ILN. WILL HOLD OFF ON MENTION IN TAFS AND SEE HOW CONVECTIVE EVOLUTION TAKES PLACE THIS EVENING. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. IN...NONE. KY...NONE. && $$ FRANKS/HICKMAN/TIPTON oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 125 PM EDT TUE AUG 3 2004 .AVIATION (18Z-18Z)... SURFACE ANALYSIS SHOWS WEAK STATIONARY FRONT ACROSS NORTHERN OHIO. LATEST SATELLITE IMAGERY SHOWS CU FIELD MORE EXTENSIVE NEAR AND SOUTH OF THE FRONT WHERE TDS ARE AROUND 70. 12Z ETA/RUC SHOW WEAK FORCING LATTER THIS AFTERNOON ALONG WITH MODERATE INSTABILITY. 12Z RUC SHOWS CAP WILL BE IN PLACE THIS AFTERNOON. ALL THIS BEING SAID WOULD NOT BE SURPRISED TO SEE ISOLATED TSRA NORTH OF DAY AND CVG. ONCE DAYTIME HEATING IS LOSS THEN CU WILL DISSIPATE. WITH LIGHT WINDS AND NEARLY CLEAR SKIES THINK FOG WILL BE AN ISSUE AGAIN TONIGHT. CVG..DAY..ILN..CMH SHOULD ALL BE MVFR WITH LUK DROPPING INTO LIFR. DAY AND CMH STARTED MVFR A BIT EARLIER WITH TD POOLING AND POSSIBLE EVE CONVECTION TO THE NORTH OF TAF SITES. AFTER 12Z ETA/GFS SHOWING CONVECTION ADVECTING INTO DAY/CMH/ILN. WILL HOLD OFF ON MENTION IN TAFS AND SEE HOW CONVECTIVE EVOLUTION TAKES PLACE THIS EVENING. && .SHORT TERM (THIS AFT)... SURFACE ANALYSIS SHOWS HIGH PRESSURE RIDGE TO THE EAST OF FORECAST AREA WITH WEAK STATIONARY FRONT NORTH OF DAY AND CMH. SATELLITE IMAGERY SHOWING MAINLY CLEAR SKIES OVER FA. HOWEVER WITH TDS RISING TO 70 TO 72 THIS PM FAIR WEATHER CU WILL FORM...ESPECIALLY IN THE VICINITY OF BOUNDARY. ANY TSRA DEVELOPMENT WILL BE NEAR BOUNDARY AND WILL LIKELY WAIT UNTIL PEAK DAYTIME HEATING. BOTH 12Z RUC AND ETA SHOWING MODERATE INSTABILITY THIS PM WITH LITTLE IN THE WAY OF FORCING. BOTH INSTABILITY AND BOUNDARY MAKE IT PRUDENT FOR AT LEAST A SLIGHT CHANCE. IF ANYTHING DEVELOPS IT HAS THE POTENTIAL FOR BEING SEVERE (PULSE). UPDATE HAS BEEN SENT TO RESOLVE AFT SKY AND WIND WORDING. ALSO TO REMOVE SLIGHT CHANCE IN THE SOUTH. && .PREVIOUS DISCUSSION SHORT TERM (TODAY THROUGH THURSDAY)... FIRST CONCERN FOR THIS MORNING IS THE ISOLATED SHOWER ACTIVITY THAT HAS DEVELOPED ACROSS NORTHERN INDIANA IN THE PAST HOUR OR SO. THIS APPEARS TO BE ASSOCIATED WITH WEAK LOW LEVEL CONVERGENT BOUNDARY EXTENDING DOWN FROM MCS MOVING ACROSS SOUTHEASTERN MICHIGAN. 00Z ETA SEEMS TO HAVE A PRETTY GOOD HANDLE ON THIS...DROPPING CONVERGENT BOUNDARY DOWN INTO NORTHERN OHIO THROUGH THIS MORNING. THEREFORE...WILL BE TOUGH TO RULE OUT A STRAY SHOWER OR TWO ACROSS OUR FAR NORTH THIS MORNING. OTHERWISE...AIRMASS PROGGED TO DESTABILIZE FAIRLY WELL THROUGH THIS AFTERNOON AS TEMPS CLIMB INTO THE UPPER 80S AND DEWPOINTS CREEP INTO THE UPPER 60S. THIS YIELDS SURFACE BASED CAPES OF 2000-3000 J/KG FOR THIS AFTERNOON AND EARLY EVENING. NOT TOO MUCH IN THE WAY OF FORCING THROUGH THIS AFTERNOON BUT SINCE THERE DOES NOT APPEAR TO BE MUCH OF A CAP THIS AFTERNOON...WILL GENERALLY GO WITH A 20 POP FOR AN ISOLATED THUNDERSTORM OR TWO. THE ETA HAS BACKED OFF CONSIDERABLY ON S/W ENERGY THAT WAS SUPPOSED TO AFFECT THE AREA TONIGHT...NOW JUST SHOWING A WEAKENING VORT MAX MOVING IN FROM THE WEST IN THE 03Z TO 06Z TIME FRAME. THE GFS IS PERHAPS A LITTLE STRONGER THAN THE ETA BUT IT TOO HINTING AT A WEAKENING VORT AS IT APPROACHES FROM THE WEST THIS EVENING. AS A RESULT...WILL CONTINUE WITH POPS FOR TONIGHT BUT SCALE THINGS BACK A BIT. DIFFICULT TO GET A HANDLE ON THINGS FOR WEDNESDAY AS GFS AND ETA BOTH APPEAR TO BE TOO STRONG WITH SHORT WAVE AND ASSOCIATED SURFACE LOW FOR WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. THE ONE PROMISING THING IS THAT AT LEAST THEY ARE BOTH PRETTY CLOSE IN THEIR TIMING. BOTH ARE INDICATING FRONT PUSHING ACROSS OUR AREA DURING THE MORE FAVORABLE TIME OF DAY SO WILL BUMP UP POPS FOR WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT...BUT DUE TO MODEL UNCERTAINTY WITH STRENGTH WILL STILL KEEP POPS IN CHANCE CATEGORY. GIVEN THE FORECAST STRENGTH OF BOTH THE ETA AND GFS...IF EITHER OF THEM END UP BEING CLOSE TO RIGHT...WE WOULD LIKELY END UP WITH DECENT SEVERE WEATHER OUTBREAK AS ETA DEVELOPING A 50+ KT 8H JET ACROSS OUR AREA BY EARLY WEDNESDAY EVENING WITH FAVORABLE SHEAR PROFILES. ALSO...PWS ONCE AGAIN PROGGED TO EXCEED 2 INCHES SO HEAVY RAIN WOULD ALSO BE A POSSIBILITY. WITH SLOWER TREND...WILL HANG ON TO A LOW CHANCE ACROSS THE SOUTHEAST INTO EARLY THURSDAY. OTHERWISE...MUCH COOLER TEMPS EXPECTED FOR THURSDAY WITH GOOD CAA DEVELOPING BEHIND FRONT. JGL && LONG TERM (THURSDAY THROUGH MONDAY)... THERE IS A CONSENSUS AMONG THE LONG RANGE MODELS (GFS, ECMWF, UKMET) ON DEVELOPING AN UPR LVL LOW ACRS SERN CANADA AND NEW ENGLAND FROM THURSDAY THROUGH SUNDAY. AS OF NOW...OUR AREA IS FORECAST TO BE TO THE WEST OF THE UPR TROF AXIS...THUS...IN THE SUBSIDENCE AREA ALOFT. AS A RESULT...WILL KEEP FORECAST DRY THURSDAY THROUGH SUNDAY. MUCH COOLER AIR WILL ADVECT INTO THE LOWER GREAT LAKES AND OHIO VALLEY REGION FROM CANADA DURING THIS PERIOD. COLDEST HIGH TEMPS ARE EXPECTED TO OCCUR ON SATURDAY WITH THE COLDEST OVERNIGHT LOWS OCCURRING SATURDAY NIGHT. UPR LVL LOW WILL MOVE EAST ON SUNDAY...ALLOWING FOR RISING H5 HEIGHTS AND A GRADUAL WARMING TREND. NEXT CHC OF PCPN IS POISED FOR MONDAY NIGHT AS WAA AHEAD OF NEXT FRONTAL SYSTEM BRINGS A CHANCE OF SHOWERS AND THUNDERSTORMS. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. IN...NONE. KY...NONE. && $$ oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LUBBOCK TX 200 PM CDT TUE AUG 3 2004 .SHORT TERM... UPPER HIGH BEGINNING TO BREAK DOWN AND MOVE SOUTH THIS AFTERNOON. MOISTURE PLUME NOTED ON WATER VAPOR IMAGERY CREEPING CLOSER AND CLOSER TO THE TEXAS AND NEW MEXICO STATE LINE WILL ALLOW FOR A ISOLATED SHOWERS OR THUNDERSTORMS TO DEVELOP LATE THIS AFTERNOON AND EVENING. 18Z SURFACE ANALYSIS SHOWS A SURFACE TROUGH AXIS FROM WESTERN KANSAS...THROUGH THE PANHANDLES...TO AROUND ROSWELL. THIS TROUGH AXIS SHOULD ALLOW FOR ENOUGH CONVERGENCE TO SPARK A FEW SHOWERS...AS DEPICTED BY THE ETA/MESOETA/RUC/SREF SOLUTIONS. A CONCERN HOWEVER...IS THE MODELS HANDLING OF THE LOW LEVEL MOISTURE. ONCE AGAIN...THE 12Z MODELS ARE UNDERESTIMATING THE AMOUNT OF MOISTURE ACROSS THE REGION...WITH SURFACE DEWPOINTS FORECAST IN THE LOW TO MID 60S...AND OBSERVED DEW POINTS ARE IN THE UPPER 60S...TO NEAR 70 DEGREES. THE 20KM RUC AND MESOETA ARE THE MORE RELIABLE MODELS IN REGARD TO LOW LEVEL MOISTURE..AND HAVE FOLLOWED THEIR SOLUTIONS FOR THE SHORT TERM PERIODS. RETAINED LOW POPS IN THE NORTHWEST FOR TONIGHT...BEFORE PRECIPITATION CHANCES BECOMING A BIT MORE WIDESPREAD BY WEDNESDAY NIGHT AND EARLY THURSDAY. MODELS INSISTENT ON A POSSIBLE MCS DURING THIS TIME FRAME...SO CHANCE POPS LOOK REASONABLE WITH PLENTY OF MOISTURE CONVERGENCE AND UPSLOPE FLOW. 14 .LONG TERM... 12Z MODEL RUN CONTINUES TO INDICATE THAT UPPER HIGH OVER THE REGION TO RETROGRESS WESTWARD INTO NEW MEXICO. UKMET/ECMWF AND GFS ALL SIMILAR ON THIS OCCURRING WITH SOME MINOR DIFFERENCES ON POSITION. AS UPPER LEVEL HIGH SHIFTS WESTWARD THROUGH THE END OF THE WEEK RIDGE OVER THE HIGH PLAINS FLATTENS AS A SERIES OF SHORTWAVES MOVE ACROSS THE NORTHERN TIER OF THE U.S...RIDGE THEN BEGINS TO AMPLIFY MONDAY AND THIS TO ALLOW FOR ANOTHER COLD FRONT TO MOVE INTO THE REGION ON A TUESDAY NIGHT/WEDNESDAY TIME FRAME. UKMET AND ECMWF MODELS NOW ALSO HINTING ON THIS SCENARIO AS WELL. MODELS ALSO SHOW SEVERAL DISTURBANCES TO ROTATE AROUND THE UPPER HIGH AND WITH POSITION AS SUCH WOULD ALLOW FOR STORMS TO DEVELOP OVER THE HIGHER TERRAIN OF NEW MEXICO AND SOUTHWEST COLORADO AND APPROACH WEST TEXAS DURING THE NIGHTIME HOURS WITHIN THE NORTHWEST FLOW. WILL CONTINUE WITH SLIGHT CHANCE OF MAINLY NOCTURNAL THUNDERSTORMS INTO EARLY NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 67 93 67 83 / 20 20 30 30 TULIA 68 96 68 85 / 10 20 30 20 PLAINVIEW 69 96 70 86 / 10 20 30 20 LEVELLAND 69 96 69 87 / 20 20 30 30 LUBBOCK 71 95 70 89 / 10 20 30 20 BROWNFIELD 70 97 69 89 / 20 20 30 30 CHILDRESS 73 100 71 87 / 10 20 30 20 SPUR 72 98 71 90 / 10 20 30 20 ASPERMONT 72 99 72 91 / 0 20 30 20 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 14/11 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 239 PM CDT TUE AUG 3 2004 .DISCUSSION...FORECAST FOCUS ON THUNDERSTORMS THROUGH WEDNESDAY. PROFILER NETWORK SHOWS THAT MID LEVEL INFLOW INTO CENTRAL WI HAS HELPED TO PRODUCE BANDS OF SHOWERS OVER CENTRAL AND SOUTHERN WI TODAY. SOUTHWEST TO WEST WINDS AT H700 WITH NORTHWEST WINDS AT H500 HAVE COMBINED TO PRODUCE CONFIGURATION SEEN ON AREA RADARS. RUC AND SATELLITE HINT AT H500 VORT MAX MOVING EAST INTO MN ATTM. SMALL BUT TIGHTLY WOUND MCS ACROSS SOUTHERN MN AND NORTHERN IA HAS BEEN MOVING STEADILY EASTWARD THIS MORNING AND AFTERNOON. THIS AREA OF SHOWERS AND EMBEDDED THUNDERSTORMS EXPECTED TO ENTER SOUTHERN WI THIS EVENING. CONFIDENCE IN REMAINDER OF FORECAST IS LOW BUT HERE IS REASONING: MODELS ARE SUFFERING FROM CONVECTIVE FEEDBACK AND DEVELOP AN UNREALISTICALLY DEEP LOW OVERNIGHT AND INTO WEDNESDAY...ALL OF WHICH PRODUCES A LARGE PRECIPITATION SHIELD OF HEAVY RAINFALL. ALTHOUGH IT SEEMS THAT RAINFALL IS LIKELY LATE TONIGHT INTO WEDNESDAY BUT HAVE PULLED BACK FROM MODEL QPF...WHICH RESULTS MAY STILL BE TOO HIGH. LATER RUNS WILL HOPEFULLY RESOLVE THIS ISSUE. HAVE OPTED TO USE MESOETA WINDS FOR FORECAST BUT HAD TO TRIM WIND SPEEDS DUE TO THE TOO DEEP SURFACE LOW TO OUR SOUTH. TEMPERATURES ALSO SUFFER FROM THE STRONG NORTHEAST FLOW AND HAVE TENDED TO BRING UP DAYTIME AND NIGHTTIME TEMPERATURES. STILL LOOKING FOR DRY WEATHER FROM WEDNESDAY NIGHT THROUGH THE WEEKEND. && .MKX...WATCHES/WARNINGS/ADVISORIES...NONE $$ wi