AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GOODLAND KS 927 PM MDT TUE JUL 29 2003 JUST FINISHED AN UPDATE. ADJUSTED THE PRECIPITATION FORECAST ACCORDING TO LATEST RADAR AND SATELLITE TRENDS. ALSO CHANGED THE WIND FORECAST BASED ON LATEST TRENDS AND RUC. KEPT OVERNIGHT MINS THE SAME. HOWEVER...HAD TO ADJUST NOT ONLY THE TEMPERATURE TREND BUT ALSO THE DEWPOINT DUE TO CONVECTION CREATING A LARGE RANGE IN VALUES ACROSS THE FORECAST AREA. .GLD...NONE. $$ BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 100 PM MDT TUE JUL 29 2003 WATER VAPOR/RUC ANALYSIS SHOWING SHORT WAVE DROPPING SOUTHEAST ACROSS SOUTHEAST WYOMING THIS AFTERNOON. SCATTERED CONVECTION EXTENDS FROM NORTHEAST COLORADO NORTHWARD ALONG BOUNDARY THROUGH WESTERN NEBRASKA AND INTO THE DAKOTAS. MAV POPS ARE VERY LOW COMPARED TO THE MET GUIDANCE AND WILL LEAN TOWARDS THE WETTER OF THE TWO AND WATCH LATEST TRENDS BEFORE BUMPING POPS UP. LOWS TONIGHT WILL BE A DEGREE OR TWO WARMER THAN LAST NIGHT WITH LOWS AROUND 60. SURFACE BOUNDARY/COLD FRONT WILL MOVE THROUGH OVERNIGHT OR EARLY IN THE MORNING AND WILL KEEP TEMPERATURES ON WEDNESDAY AT OR SLIGHTLY ABOVE READINGS TODAY WITH UPPER 80S NORTHWEST TO LOWER 90S EAST. WILL INSERT A SLIGHT CHANCE FOR THUNDERSTORMS IN THE SOUTH/SOUTHWEST WHERE GREATER INSTABILITY RESIDES IN VICINITY OF FRONT. THURSDAY THROUGH SATURDAY...THURSDAY WILL REMAIN DRY AND HEAT UP AS WEST/SOUTHWEST COMPONENT ALLOWS HIGH TEMPERATURES TO CLIMB INTO THE 96 TO 103 DEGREE RANGE FROM WEST TO EAST. WILL KEEP THURSDAY NIGHT DRY ALTHOUGH GFS SHOWING A WEAK DISTURBANCE DROPPING SOUTHEAST IN NORTHWEST FLOW ALOFT. WILL KEEP A SLIGHT CHANCE FOR THUNDERSTORMS ON FRIDAY AS LEE TROUGH/BOUNDARY SETS UP OVER THE AREA AND MOIST UPSLOPE FLOW PERSISTS NORTH OF THE TROUGH. FRIDAY NIGHT AND SATURDAY...NORTHWEST UPPER FLOW CONTINUES AND GFS BRINGS ANOTHER DISTURBANCE OVER THE AREA..CHANCE POPS ON SATURDAY LOOK GOOD WITH HIGHS FALLING BACK INTO THE LOWER 90S. SUNDAY AND MONDAY...RIDGE AXIS APPROACHES AND HAVE ADJUSTED GRIDS TO SHOW A WARMING TREND. GFS IS SHOWING QPF AS RIDGE AXIS MOVES INTO THE AREA...HOWEVER LEFT SUNDAY/MONDAY DRY FOR NOW WITH RIDGE AMPLIFYING ACROSS THE PLAINS. .GLD...NONE. $$ MCGUIRE ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1059 PM EDT TUE JUL 29 2003 MAIN FCST CONCERNS ON UPDATE ARE LINGERING SHRA THIS EVNG OVER FAR WRN COUNTIES AND THEN TIMING OF MORE SIGNIFICANT BATCH OF SHRA LATE TONIGHT AHD OF INCOMING CDFNT. WV IMAGERY AND RUC ANALYSIS INDICATES SHRTWV RDG OVR UPR MI SANDWICHED BTWN VORTEX OVER WRN QUEBEC AND UPR LO OVER SRN MANITOBA. DIURNAL SHRA/TSRA GENLY HAVE DIED OFF ACROSS CWA EXCEPT FOR A FEW ISOLD SHRA OVER FAR WRN COUNTIES WHICH APPEAR TO BE FORMING ALG WMFNT OVR NCNTRL WI. TOOK OUT EVNG SHRA FOR ALL BUT WRN COUNTIES ON EARLIER UPDATE. 00Z MODELS SHOW SHRTWV OVER ND ROTATING EWD AROUND BASE OF UPR LOW OVR MANITOBA AND INTO MN AND NW WI BY 12Z AS SFC CDFNT MOVES SLOWLY INTO NE MN AND NW WI. MODELS SHOW GOOD DIFLUENCE AHD OF UPR LOW/TROF INTO WRN UPR MI AS WELL AS DIVERGENCE IN RRQ OF 50 KT JET MAX AND DPVA AHD OF SHRTWV. STRENGTHENING 8H JET OF 20-25 KT OVR WRN UPR MI PER ETA AND RUC AND INCRG THETA-E ADVECTION...AND 305K ISENTROPIC ASCENT SHOULD HELP INCREASE SHRA ACTIVITY OVER WRN COUNTIES BTWN 08-12Z. THUS...KEPT WORDING OF SCATTERED SHOWERS LATE TONIGHT FOR 4 WRN COUNTIES. TEMPS LOOKED GOOD...SO MADE NO CHANGES THERE. .MQT...NONE. VOSS .LONGER TERM(WED-FRI)...THE MDLS CONTINUE THEIR TREND OF SLOWING THE MOVEMENT OF THE UPR LOW AND ASSOCIATED FRONT...AND KEEPING THE LOW FARTHER WEST. THIS IS MOST LIKELY DUE TO THE RETROGRADING NATURE OF THE UPR LOW OVER QUEBEC. HOWEVER...THE MDLS ARE IN FAIRLY GOOD AGREEMENT THAT THE UPR LOW WILL DIVE INTO NRN MN WED...WITH THE S/WV RIDGE MOVING FROM CENTRAL UPPER MICHIGAN INTO LK HURON DURING THE DAY. THIS WILL ALLOW FOR INCREASING UPR DIFFLUENCE AND DPVA TO MOVE INTO THE WESTERN AND CENTRAL UP THRU THE AFTN. THE MDLS ALSO SHOW MODEST H8 POSITIVE DIFFERENTIAL THETA-E ADVECTION DURING THE DAY DUE TO A 30 KT LLJ FEATURE NOSING INTO THE WEST HALF OF UPR MICH DURING THE DAY. ALL OF THIS SHOULD LEAD TO SCT SHOWERS AND THUNDERSTORMS TO MOVE INTO WESTERN UPPER MICH AND CONTINUE TO SLOWLY MOVE EAST DURING THE DAY AS THE FRONT APPROACHES. OVER THE EAST...THE MDLS SUGGEST THE S/WV RIDGE WILL HANG ON UNTIL LATE AFTN...ALONG WITH MUCH DRIER AIR. IN FACT...THE ETA SHOWS NVA THRU MID-LATE AFTN OVER THE EAST. GIVEN THE FACT THAT THE FRONT WILL STILL BE WELL WEST OF THE EASTERN UP...HAVE OPTED TO GO ISO TSRA LATE OVER THE FAR EAST. OTHERWISE...WILL CONTINUE WITH SCT TSRA OVER THE WEST AND CENTRAL DURING THE DAY. SPC CURRENTLY HAS THE WESTERN 2/3 OF THE CWFA IN DAY 2 SLIGHT RISK. ALTHOUGH WIND FIELDS TO NOT LOOK TERRIBLY IMPRESSIVE...LOW WET BULB ZERO VALUES OF AROUND 8-9KFT WILL ALLOW FOR THE POTENTIAL FOR MARGINAL SVR HAIL FOR ANY ORGANIZED STORM...ESPECIALLY OVER THE WEST HALF WHERE BEST FRONTAL FORCING WILL EXIST. BEST UPPER FORCING AND PVA MOVES THRU THE CWFA OVERNIGHT. THE GFS AND ETA ARE ACTUALLY IN REMARKABLE AGREEMENT WITH TIMING/POSITION OF INDIVIDUAL S/WVS ROTATING AROUND THE UPR LOW. THE MAIN S/WV AND BEST UPR DIFFLUENCE WILL ROTATE INTO THE CWFA WED NIGHT...ALONG WITH THE DEEP MOISTURE (PWAT VALUES 1.45 INCHES). THIS SHOULD ALLOW FOR NUMEROUS SHOWERS TO CONTINUE THRU THE NIGHT ACROSS THE ENTIRE CWFA. THIS AGREES WITH MOS POPS QUITE WELL. EVEN THOUGH SFC BASED INSTABILITY WILL DECREASE OVERNIGHT...ELEVATED INSTABILITY WILL TEND TO INCREASE AS MID LVL LAPSE RATES DECREASE DUE TO PROXIMITY OF COLD POOL ALOFT. THE ETA AND GFS CONTINUE TO SHOW THE UPR LOW OVER FAR WESTERN LK SUPERIOR/NRN MN ON THU. THEY ARE ALSO IN GOOD AGREEMENT IN SHOWING THE FIRST S/WV TO ROTATE INTO LK SUPERIOR THU MORNING. THIS MAY ALLOW FOR SOME DRYING THU MORNING THRU THE AFTN ESPECIALLY OVER THE EAST WHERE THE MDLS SUGGEST A WEAK DRY SURGE TO MOVE NWD. WITH THE NVA AND WEAK DOWNWARD MOTION...IT IS POSSIBLE THAT AREAS (ESPECIALLY SOUTH AND EAST) WILL SEE A DRY PERIOD THU MORNING/AFTN BEFORE THE NEXT S/WV APPROACHES FROM THE SOUTHWEST. THINK THAT THE WEST WILL STAY SHOWERY ALL DAY DUE TO PROXIMITY OF UPR LOW. HOWEVER...WILL KEEP THE ENTIRE UP UNDER SCT POPS ALL DAY THU DUE TO UNCERTAINTY OF S/WV TIMING/POSITION AND POSSIBLE DIURNAL TYPE CONVECTION WITH COLD POOL ALOFT. WILL GO WITH HIGHER POPS OVER THE WEST...HOWEVER. REALLY NOT MUCH CHANGE FOR THU NIGHT AND FRI. THE UPR LOW REMAINS CUT OFF FROM THE MEAN FLOW WHILE SLOWLY MOVING EAST...SO WILL CONTINUE WITH CHC POPS. WILL ONLY GO WITH ISO T SINCE CLDS WILL LIMIT SFC HEATING SIGNIFICANTLY AND MID LAPSE RATES DECREASE. OVERALL...TEMPS WILL REMAIN NEAR OR SLIGHTLY BELOW NORMAL FOR THE NEXT SEVERAL DAYS. WARMEST DAY WILL BE ON WED WHERE TEMPS COULD BE IN THE LOWER 80S ESPECIALLY CENTRAL AND EAST WHERE CLDS ARRIVE LATEST. MRD DAYS 4-7 (SAT-TUES)... GFS/ECMWF/UKMET/CANADIAN MODELS CONTINUE TO BE IN REMARKABLY GOOD AGREEMENT IN THE MEDIUM RANGE IN HANDLING THE SYNOPTIC SCALE FEATURES. GFS ALSO SHOWING GOOD RUN TO RUN CONSISTENCY WITH A SLIGHT TREND TOWARD A SLOWER LESS PROGRESSIVE PATTERN SAT INTO SUNDAY. ECMWF CONTINUES TO TREND TOWARD A MORE SLOWLY MOVING CLOSED LOW AND A MORE AMPLIFIED TROF... TRENDING TOWARD THE GFS SOLUTION. UPPER LEVEL LOW DROPS INTO WESTERN LAKE SUPERIOR SAT AS OCCLUDED SFC SLOW STALLS AND SYSTEM BECOMES VERTICALLY STACKED. WITH BLOCKING RIDGE OVER THE WESTERN ATLANTIC AND RISING HEIGHTS OVER THE WESTERN U.S. WILL TREND GRIDDED FCST WITH A SLOWER DEPARTING UPPER LOW SUN AND INTRODUCE A CHANCE OF SHWRS. COLD POOL ALOFT WITH THE LOW COMBINED WITH STEEP LOW LEVEL LAPSE RATES... LOW FREZ LEVELS AND MODEST CAPE/L.I. VALUES WARRANTS MENTION OF THUNDER FOR SATURDAY AS WELL. A STRONG SHORTWAVE MOVING INTO THE PACIFIC NORTHWEST AND BRITISH COLUMBIA HELPS CARVE OUT A TROF AND EVENTUALLY AN IMPRESSIVE CUT OFF LOW PUSHING THE UPPER RIDGE OVER THE MOUNTAIN WEST INTO THE PLANS AND HELPING KICK THE GREAT LAKES LOW EASTWARD BY MON. RISING HEIGHTS COMBINED WITH INCREASED DRYING/SUBSIDENCE AND LOW LVL ANTI- CYCLONIC FLOW WILL RESULT TO A RETURN TO FAIR WX MON-TUES ALTHOUGH FUTURE MODEL RUNS MAY SLOW THIS PROCESS WHICH MAY NECESSITATE A FORECAST FOR PRECIP TO CONTINUE INTO MON. ED F mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 AM EDT TUE JUL 29 2003 SHORT TERM...TONIGHT. MAIN FCST CONCERNS ARE LINGERING SHRA/TSRA TRENDS. WV IMAGERY AND RUC ANALYSIS INDICATED NW FLOW INTO THE WRN LAKES BTWN VORTEX OVER NE ONTARIO AND SHRTWV RDG OVER NW ONTARIO AHEAD OF NEXT H5 LO OVER NW MANITOBA. SHRTWV LOBE EXTENDED FROM WRN MANITOBA INTO NW ND. AT THE SFC...UPSTREAM TROF EXTENDED FROM NW MN INTO CNTRL SD WHILE WEAK GRADIENT PREVAILED OVER UPR MI AS WEAK RDG EXTENDED FROM JAMES BAY TOWARD IL. SCT SHRA/TSRA HAVE DEVELOPED ALONG LK SUPERIOR BREEZE FRONT IN MARQUETTE INTO NW DELTA COUNTY AND OVER SW UPR MI WHERE MORE ABUNDANT SUNSHINE AND SFC HEATING HAD PUSHED T/TD TO NEAR 81/61. INSTABILITY WITH CAPES AROUND 1000 J/KG...PER LAPS ANALYSIS...AND WEAK LOW AND MID LVL WIND FIELDS WERE SUFFICIENT TO SUPPORT ISOLD PULSE CELLS WITH BRIEF HEAVY RAIN AND SOME MAINLY SMALL HAIL. ONLY A FEW -SHRA OR SPRINKLES INDICATED UPSTREAM OVER THE MN ARROWHEAD...PER KDLH RADAR. TONIGHT...EXPECT DIURNAL SHRA/TSRA OVER INLAND PORTIONS OF CNTRL AND SRN UPR MI TO GRADUALLY DIMINISH THIS EVENING LEAVING A LULL IN THE PCPN BEFORE NEXT BATCH OF PCPN ARRIVES FROM THE WEST. 12Z/18Z ETA SCENARIO LOOKS REASONABLE WHERE SHRTWV WILL SUPPORT SCT SHRA/TSRA MOVING INTO WRN UPR MI LATE (BTWN 06Z-12Z). SHRA/TSRA WILL BE SUPPORTED BY DECENT UPR LVL DIV/DIFFLUENCE AND DPVA ALONG WITH GOOD 305K ISENTROPIC LIFT AS SW H8 WIND THETA-E ADVECTION INCREASES. JLB .LONGER TERM(WED-FRI)...THE MDLS CONTINUE THEIR TREND OF SLOWING THE MOVEMENT OF THE UPR LOW AND ASSOCIATED FRONT...AND KEEPING THE LOW FARTHER WEST. THIS IS MOST LIKELY DUE TO THE RETROGRADING NATURE OF THE UPR LOW OVER QUEBEC. HOWEVER...THE MDLS ARE IN FAIRLY GOOD AGREEMENT THAT THE UPR LOW WILL DIVE INTO NRN MN WED...WITH THE S/WV RIDGE MOVING FROM CENTRAL UPPER MICHIGAN INTO LK HURON DURING THE DAY. THIS WILL ALLOW FOR INCREASING UPR DIFFLUENCE AND DPVA TO MOVE INTO THE WESTERN AND CENTRAL UP THRU THE AFTN. THE MDLS ALSO SHOW MODEST H8 POSITIVE DIFFERENTIAL THETA-E ADVECTION DURING THE DAY DUE TO A 30 KT LLJ FEATURE NOSING INTO THE WEST HALF OF UPR MICH DURING THE DAY. ALL OF THIS SHOULD LEAD TO SCT SHOWERS AND THUNDERSTORMS TO MOVE INTO WESTERN UPPER MICH AND CONTINUE TO SLOWLY MOVE EAST DURING THE DAY AS THE FRONT APPROACHES. OVER THE EAST...THE MDLS SUGGEST THE S/WV RIDGE WILL HANG ON UNTIL LATE AFTN...ALONG WITH MUCH DRIER AIR. IN FACT...THE ETA SHOWS NVA THRU MID-LATE AFTN OVER THE EAST. GIVEN THE FACT THAT THE FRONT WILL STILL BE WELL WEST OF THE EASTERN UP...HAVE OPTED TO GO ISO TSRA LATE OVER THE FAR EAST. OTHERWISE...WILL CONTINUE WITH SCT TSRA OVER THE WEST AND CENTRAL DURING THE DAY. SPC CURRENTLY HAS THE WESTERN 2/3 OF THE CWFA IN DAY 2 SLIGHT RISK. ALTHOUGH WIND FIELDS TO NOT LOOK TERRIBLY IMPRESSIVE...LOW WET BULB ZERO VALUES OF AROUND 8-9KFT WILL ALLOW FOR THE POTENTIAL FOR MARGINAL SVR HAIL FOR ANY ORGANIZED STORM...ESPECIALLY OVER THE WEST HALF WHERE BEST FRONTAL FORCING WILL EXIST. BEST UPPER FORCING AND PVA MOVES THRU THE CWFA OVERNIGHT. THE GFS AND ETA ARE ACTUALLY IN REMARKABLE AGREEMENT WITH TIMING/POSITION OF INDIVIDUAL S/WVS ROTATING AROUND THE UPR LOW. THE MAIN S/WV AND BEST UPR DIFFLUENCE WILL ROTATE INTO THE CWFA WED NIGHT...ALONG WITH THE DEEP MOISTURE (PWAT VALUES 1.45 INCHES). THIS SHOULD ALLOW FOR NUMEROUS SHOWERS TO CONTINUE THRU THE NIGHT ACROSS THE ENTIRE CWFA. THIS AGREES WITH MOS POPS QUITE WELL. EVEN THOUGH SFC BASED INSTABILITY WILL DECREASE OVERNIGHT...ELEVATED INSTABILITY WILL TEND TO INCREASE AS MID LVL LAPSE RATES DECREASE DUE TO PROXIMITY OF COLD POOL ALOFT. THE ETA AND GFS CONTINUE TO SHOW THE UPR LOW OVER FAR WESTERN LK SUPERIOR/NRN MN ON THU. THEY ARE ALSO IN GOOD AGREEMENT IN SHOWING THE FIRST S/WV TO ROTATE INTO LK SUPERIOR THU MORNING. THIS MAY ALLOW FOR SOME DRYING THU MORNING THRU THE AFTN ESPECIALLY OVER THE EAST WHERE THE MDLS SUGGEST A WEAK DRY SURGE TO MOVE NWD. WITH THE NVA AND WEAK DOWNWARD MOTION...IT IS POSSIBLE THAT AREAS (ESPECIALLY SOUTH AND EAST) WILL SEE A DRY PERIOD THU MORNING/AFTN BEFORE THE NEXT S/WV APPROACHES FROM THE SOUTHWEST. THINK THAT THE WEST WILL STAY SHOWERY ALL DAY DUE TO PROXIMITY OF UPR LOW. HOWEVER...WILL KEEP THE ENTIRE UP UNDER SCT POPS ALL DAY THU DUE TO UNCERTAINTY OF S/WV TIMING/POSITION AND POSSIBLE DIURNAL TYPE CONVECTION WITH COLD POOL ALOFT. WILL GO WITH HIGHER POPS OVER THE WEST...HOWEVER. REALLY NOT MUCH CHANGE FOR THU NIGHT AND FRI. THE UPR LOW REMAINS CUT OFF FROM THE MEAN FLOW WHILE SLOWLY MOVING EAST...SO WILL CONTINUE WITH CHC POPS. WILL ONLY GO WITH ISO T SINCE CLDS WILL LIMIT SFC HEATING SIGNIFICANTLY AND MID LAPSE RATES DECREASE. OVERALL...TEMPS WILL REMAIN NEAR OR SLIGHTLY BELOW NORMAL FOR THE NEXT SEVERAL DAYS. WARMEST DAY WILL BE ON WED WHERE TEMPS COULD BE IN THE LOWER 80S ESPECIALLY CENTRAL AND EAST WHERE CLDS ARRIVE LATEST. MRD DAYS 4-7 (SAT-TUES)... GFS/ECMWF/UKMET/CANADIAN MODELS CONTINUE TO BE IN REMARKABLY GOOD AGREEMENT IN THE MEDIUM RANGE IN HANDLING THE SYNOPTIC SCALE FEATURES. GFS ALSO SHOWING GOOD RUN TO RUN CONSISTENCY WITH A SLIGHT TREND TOWARD A SLOWER LESS PROGRESSIVE PATTERN SAT INTO SUNDAY. ECMWF CONTINUES TO TREND TOWARD A MORE SLOWLY MOVING CLOSED LOW AND A MORE AMPLIFIED TROF... TRENDING TOWARD THE GFS SOLUTION. UPPER LEVEL LOW DROPS INTO WESTERN LAKE SUPERIOR SAT AS OCCLUDED SFC SLOW STALLS AND SYSTEM BECOMES VERTICALLY STACKED. WITH BLOCKING RIDGE OVER THE WESTERN ATLANTIC AND RISING HEIGHTS OVER THE WESTERN U.S. WILL TREND GRIDDED FCST WITH A SLOWER DEPARTING UPPER LOW SUN AND INTRODUCE A CHANCE OF SHWRS. COLD POOL ALOFT WITH THE LOW COMBINED WITH STEEP LOW LEVEL LAPSE RATES... LOW FREZ LEVELS AND MODEST CAPE/L.I. VALUES WARRANTS MENTION OF THUNDER FOR SATURDAY AS WELL. A STRONG SHORTWAVE MOVING INTO THE PACIFIC NORTHWEST AND BRITISH COLUMBIA HELPS CARVE OUT A TROF AND EVENTUALLY AN IMPRESSIVE CUT OFF LOW PUSHING THE UPPER RIDGE OVER THE MOUNTAIN WEST INTO THE PLANS AND HELPING KICK THE GREAT LAKES LOW EASTWARD BY MON. RISING HEIGHTS COMBINED WITH INCREASED DRYING/SUBSIDENCE AND LOW LVL ANTI- CYCLONIC FLOW WILL RESULT TO A RETURN TO FAIR WX MON-TUES ALTHOUGH FUTURE MODEL RUNS MAY SLOW THIS PROCESS WHICH MAY NECESSITATE A FORECAST FOR PRECIP TO CONTINUE INTO MON. ED F .MQT...NONE. mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1132 AM EDT TUE JUL 29 2003 LATEST RADAR IMAGERY SHOWS A LINE OF SHOWERS...WITH OCCASIONAL EMBEDDED THUNDER...LOCATED FROM NEAR ONTONAGON SOUTHEAST TO NEAR ESCANABA. THE ACTIVITY HAS SHOWN SOME SLIGHT WEAKENING OVER THE PAST HOUR AS IT SINKS SLOWLY SOUTH. THIS PCPN LINES UP WELL WITH AN AXIS OF NEGATIVE 850-500MB DIFFERENTIAL THETA-E AS DEPICTED BY THE RUC. IN ADDITION...THE RUC SHOWS A POCKET OF 850MB CONVERGENCE AND RH VALUES AOA 85 PERCENT...WHICH IS HELPING THE CONVECTIVE INSTABILITY TO BE REALIZED. INDICATIONS ARE THAT THIS AREA OF CONVECTIVE INSTABILITY WILL SINK SOUTH AND EAST THROUGH THE AFTERNOON AND 850 MB CONVERGENCE WILL WEAKEN AS THE BOUNDARY LAYER BECOMES MORE THOROUGHLY MIXED. IN ADDITION TO THIS CONVECTION...THERE IS THE CHANCE FOR ADDITIONAL ACTIVITY TO DEVELOP DURING THE AFTERNOON AS THINGS HEAT UP. 12Z SOUNDINGS FROM KINL...KGRB...AND KAPX INDICATE THE POTENTIAL FOR SOME INSTABILITY THIS AFTERNOON WITH HIGHS IN THE MID 70S TO AROUND 80 AND DEWPOINTS IN THE 50S. ALTHOUGH FORECAST SBCAPES ARE UNIMPRESSIVE...AROUND AOB 600 J/KG...WE WILL LIKELY SEE A FEW SHRA DEVELOP DURING THE AFTERNOON. SOLAR HEATING WILL OBVIOUSLY PLAY A LARGE ROLE IN WHERE WE SEE SHRA/TSRA DEVELOP THIS AFTERNOON...AND THE LATEST VISIBLE IMAGERY AND RUC OUTPUT SUGGEST THIS WILL BE MOST PRONOUNCED OVER THE EAST AND SOUTHWEST. HOWEVER...WITH THE CURRENT SHOWERS AND CLOUD COVER EXPECTED TO DIMINISH...THE REMAINDER OF THE CWFA SHOULD STILL SEE THINGS WARMUP FAIRLY WELL BY LATE AFTERNOON. THE GREATEST INSTABILITY...AND POTENTIAL FOR THUNDER...STILL LOOKS LIKE IT WILL BE OVER THE SOUTHWEST...WHERE THE BEST COMBINATION OF SURFACE HEATING AND HIGHER DEWPOINTS ARE EXPECTED. THE LOCATION OF LAKE BOUNDARIES AND ENHANCED LOW LEVEL CONVERGENCE WILL ALSO BE INSTRUMENTAL IN THE DEVELOPMENT OF SHRA/TSRA. THE 00Z WSETA SUGGESTS LOW LEVEL CONVERGENCE WILL BE MAXIMIZED ALONG THE KEWEENAW...AND IN AN AXIS FROM SOUTHERN MARQUETTE AND NORTHERN DICKINSON COUNTIES EASTWARD THROUGH SOUTHERN SCHOOLCRAFT COUNTY. WITH SOME PCPN ONGOING...AND WITH ENOUGH FACTORS SUGGESTING THE POTENTIAL FOR A FEW SHRA/TSRA...WILL MAINTAIN A CHANCE OF ISOLATED SHOWERS ACROSS THE ENTIRE CWFA...WHILE MENTIONING THE POSSIBILITY OF THUNDER OVER THE SOUTHWEST. ZONES WILL BE OUT BY 1155 PM EDT. .MQT...NONE. TRH mi AREA FORECAST DISCUSSION...18Z AVIATION ISSUANCE NATIONAL WEATHER SERVICE SPRINGFIELD MO 109 PM CDT TUE JUL 29 2003 .DISCUSSION... EARLY THIS AFTERNOON A WEAK SURFACE BOUNDARY EXTENDED ALONG THE ARKANSAS BORDER. MORNING CONVECTION WAS TAPERING OFF ACROSS OUR FAR SOUTHEAST COUNTIES...AS THE UPPER WAVE WHICH TRIGGERED THE PRECIPITATION PUSHED TOWARD TENNESSEE. LOOKING UPSTREAM...ANOTHER UPPER WAVE WAS EMBEDDED IN THE NORTHWEST FLOW ACROSS THE CENTRAL PLAINS. MAIN SHORT TERM FORECAST CONCERN...DEALS ANY ADDITIONAL CONVECTIVE DEVELOPMENT THIS AFTERNOON AS THE PLAINS ENERGY INTERACTS WITH THE FRONT ACROSS SOUTHERN MISSOURI. PREVIOUS GRIDS HAD PRECIPITATION ENDING ACROSS MOST LOCATIONS BY AFTERNOON. WITH THE AFOREMENTIONED FEATURES IN THE AREA...DECIDED TO KEEP 30 POPS GOING DURING THE REMAINDER OF THE AFTERNOON FOR LOCATIONS ACROSS SOUTHERN MISSOURI. THE LATEST RUN OF THE RUC HINTS AT SOME DEVELOPMENT SOUTH OF HIGHWAY 60 AFTER 21Z. && .AVIATION... AT THIS TIME...WILL NOT ADD THUNDER IN THE KJLN AND KSGF TAFS. NOT CONFIDENT THAT CONVECTION WILL BE WIDESPREAD ENOUGH TO INCLUDE. DID ADD A TEMPO FOR BROKEN 3000 FT CEILINGS THIS AFTERNOON TO HINT OF POSSIBLE DEVELOPMENT. IN ADDITION...CURRENT OBSERVATIONS SHOW SOME BROKEN CEILINGS RANGING FROM 2500 TO 4000 FT. WITH LIGHT WINDS AND ABUNDANT LOW LEVEL MOISTURE IN PLACE...PATCHY FOG IS POSSIBLE OVERNIGHT. WILL LET THE NEXT SHIFT EVALUATE WHETHER THIS NEEDS TO BE ADDED TO THE 00Z TAFS. IF CONVECTION DOES DEVELOP...LINGERING CLOUD COVER WOULD HELP TO INHIBIT FOG FORMATION. && .SGF WATCHES/WARNINGS/ADVISORIES... .MO...NONE. .KS...NONE. $$ SAW mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1020 AM EDT TUE JUL 29 2003 LATE MORNING UPDATE WILL BE ISSUED ALTHOUGH CHANGES FOR THIS AFTERNOON WILL BE FEW. EAST TO WEST FRONT CONTINUES TO DRIFT SLOWLY SOUTHWARD. LATEST MESO ANALYSES INDICATE CONFLUENT ASYMPTOTE IN SURFACE WIND FIELD EXTENDS FROM NORTHERN POLK COUNTY EASTWARD THROUGH NORTHERN MECKLENBURG COUNTY AND ROWAN COUNTY. MOISTURE CONVERGENCE AXIS ACCOMPANIES THE WIND CONFLUENCE. NORTH OF THIS FEATURE... SURFACE WINDS ARE NORTHEAST WHILE SOUTHWEST FLOW CONTINUES ELSEWHERE TO THE SOUTH... AT LEAST EAST OF THE MOUNTAINS. THERE ARE HINTS OF A WEST TO NORTHWEST FLOW IN THE MOUNTAINS... BUT TERRAIN IS MAKING RESOLUTION OF LOWER LEVEL WIND RATHER DIFFICULT. LATEST RUC SHOWS 500 MB TROUGH AND ASSOCIATED VORTICITY MAXIMUM JUST TO OUR WEST CONTINUING TO MOVE GRADUALLY EASTWARD. AIR MASS OVER CWA IS UNSTABLE... BUT NOT SUFFICIENTLY UNSTABLE TO INDICATE SIGNIFICANT POTENTIAL OF SEVERE WEATHER. FORECAST CAPES DURING TIME OF MAXIMUM HEATING DISPLAY A GRADIENT RANGING FROM 1900 IN WEST TO 3200 IN EAST. WILL CONTINUE POPS IN CURRENT FORECAST THIS AFTERNOON BUT PLAN TO INCREASE INTO LIKELY CATEGORY FOR OUR EASTERN ZONES. CONCERN FOR ISOLATED SEVERE WEATHER THIS AFTERNOON AND THIS EVENING WILL BE CENTERED AROUND THE MOST UNSTABLE AIR IN THE EAST AND THE SURFACE MOISTURE CONVERGENCE MAXIMUM. .GSP... GA...NONE. NC...NONE. SC...NONE. $$ LGL sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 932 PM CDT TUE JUL 29 2003 MONITORING CONTINUES OF CONVECTIVE/STRATIFORM RAIN IN WESTERN MINNESOTA. EVENING SHOWERS NOW HAVE DISSIPATED IN THE LOCAL AREA. LATEST 02Z REGIONAL RADARS AND INFRARED GOES-12 IMAGERY INDICATE THE CONVECTIVE COMPLEX OVER WESTERN MINNESOTA TO BE RAPIDLY DECAYING. SBCAPES ACROSS MINNESOTA ARE AROUND 1000 J/KG BUT THIS IS JUST NOT ENOUGH TO SUSTAIN LONGER-LIVED SYSTEM IN THE WEAK WIND SHEAR ENVIRONMENT. 0-3KM/0-6KM BULK SHEAR ONLY AROUND 20 KTS WHICH IS QUITE LOW FOR COLD-POOL SQUALL LINE SUSTAINANCE AND ALSO MUCH BELOW SUPERCELLULAR MODES. 21Z/00Z LATEST RUC DOES INDICATE SOME LOW-LEVEL CONVERGENCE /THETAE CONVERGENCE/ MOVING IN LATER TONIGHT WITH THE LOWER-LEVEL FRONT. THUS...INCREASING TREND OVERNIGHT TO PRECIPITATION CHANCES STILL LOOKS REASONABLE. NO REAL LOW-LEVEL JET ACTIVITY IN THIS ONE AND SLATER IA IS ONLY 10KTS FROM THE SOUTH. WILL KEEP THE CURRENT TRENDS FROM EARLIER FORECASTS. HAVE UPDATE SKY TRENDS WITH TSRA DEBRIS WORKING EAST. ALSO HAVE RAISED LOWS A BIT NORTH OF KDLL-KONA LINE WITH A BIT MORE CLOUD COMING IN. WEDNESDAY IS STILL ON TRACK AND COULD END UP TO BE RAIN PRODUCER FOR MUCH OF THE FORECAST AREA. I WILL ADJUST QPF GRIDS UPWARD BECAUSE IF IT DOES RAIN...WITH 1.5" PRECIPITABLE WATER VALUES...AND SLOW MOVEMENT TO THE SYSTEM...TOTALS COULD BE 0.50-1.00 INCHES. BEST SCENARIO IS IF THE FRONT PAUSED WEST OF THE FORECAST AREA NEAR SUNRISE AND SUNSHINE DESTABILIZED AIR MASS FOR AFTERNOON TSRA. RAINFALL TOTALS WILL BE VERY DEPENDENT ON THE AMOUNT OF CAPE BUILT WEDNESDAY. 18Z/29 ETA RUN SUGGESTED THIS POSSIBLE OUTCOME WITH 3- 4000J/KG SBCAPE BY 18Z/WED. IT SEEMS A LATE-MORNING CONVECTIVE INITIATION COULD OCCUR TOO. SEVERE THREATS WOULD BE WIND AND POSSIBLY HAIL MAINLY ON THE INITIATION AREA OF THE STORMS SHOULD CAPE GROW LARGE. UPDATED TEXT PRODUCTS COMING. .LSE...WATCHES/WARNINGS/ADVISORIES...NONE. $$ BAUMGARDT wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 348 AM EDT WED JUL 30 2003 THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR THUNDERSTORMS TODAY AND TONIGHT. WATER VAPOR IMAGERY AND RUC/ETA SHOWING CLOSED LOWS SPINNING OVER SOUTHWEST QUEBEC AND SOUTHERN MANITOBA. A BROAD RIDGE CONTINUES TO BUILD OVER THE NORTHERN ROCKIES. SHORTWAVE ENERGY IS BEING PUSHED OUT AHEAD OF THE MANITOBA LOW AND IS TRAVELING THROUGH NORTHERN MINNESOTA PRODUCING NUMEROUS THUNDERSTORMS. THESE STORMS ARE FIRING ALONG AN 850MB THETA-E RIDGE WHICH EXTENDS ACROSS WESTERN ONTARIO. SURFACE ANALYSIS SHOWING A WEAK RIDGE OVER THE UPPER GREAT LAKES AND A LOW OVER NORTHERN MINNESOTA DRAGGING A COLD FRONT THROUGH SOUTHWEST MINNESOTA AND SOUTH DAKOTA. A RIDGE BUILDING OVER MONTANA IS PUSHING THE COLD FRONT TOWARDS THE UPPER GREAT LAKES. A STATIONARY FRONT STILL STRETCHES ACROSS THE SOUTHERN STATES FROM TEXAS TO NORTH CAROLINA. THE MID LEVEL LOW OVER MANITOBA WILL SHIFT INTO THE LAKE OF THE WOODS AREA BY LATE THIS AFTERNOON. THE SHORTWAVE ENERGY WILL CYCLE THROUGH CENTRAL MINNESOTA AND WISCONSIN TODAY INTO THE WESTERN U.P. THE SURFACE LOW WILL BECOME MORE DEFINED OVER WESTERN ONTARIO AS THE ACCOMPANYING COLD FRONT SLIDE INTO NORTHWEST WISCONSIN AND WESTERN LAKE SUPERIOR. THE 310K ISENTROPIC ANALYSIS INDICATE ASCENT OVER THE FORECAST AREA...AND 850-500MB MEAN RELATIVE HUMIDITY WILL BE GREATER THAN 70 PERCENT. THE LATEST RUNS SHOWING ALSO THE HIGHEST RH AND LOWEST 310K CONDENSATION PRESSURE DEFICIT OVER CENTRAL ONTARIO JUST NORTH OF LAKE SUPERIOR. THIS IS ALSO AREA OF THE STRONGEST OMEGA AND AREA OF UPPER LEVEL WIND DIVERGENCE. AS THE LOW TREKS CLOSER TO THE U.P. TODAY...THE ADDED MOISTURE AND INSTABILITY SHOULD TRIGGER SCATTERED SHOWERS AND THUNDERSTORMS ACROSS THE REGION. TRAJECTORY FORECAST SUGGEST TEMPERATURES IN THE LOW 80S TODAY...HOWEVER... CLOUDY CONDITION AHEAD OF THE APPROACHING COLD FRONT WILL LIMIT HEATING. TEMPERATURES SHOULD STILL REACH INTO THE MID AND UPPER 70S. A 25 KNOT LOW LEVEL JET WILL SHIFT ACROSS THE FORECAST AREA TODAY. WITH THE WARM AIR ADVECTION AHEAD OF THE FRONT...EXPECT TO SEE SOME OF THESE WINDS MIX TO SURFACE. LI'S WILL LOWER TO -2...AND K-INDEX SHOULD REACH 32. VERY LITTLE SHEAR WILL BE PRESENT TODAY...SO ANY THUNDERSTORMS THAT MAY PRODUCE HEAVY RAINS AND GUSTY CONDITIONS. SMALL HAIL IS POSSIBLE ALSO. THE CLOSED MID LEVEL LOW WILL EDGE INTO THE ARROWHEAD AREA OF NORTHEAST MINNESOTA OVERNIGHT. SHORTWAVE ENERGY WILL SHIFT ACROSS THE FORECAST AREA TONIGHT. THE SURFACE LOW WILL PUSH INTO THE FAR WESTERN LAKE SUPERIOR...WHILE THE COLD FRONT WILL PUSH INTO WESTERN U.P. THE THETA-E RIDGE WILL WEAKEN AS IT SLIDE INTO THE CENTRAL UPPER PENINSULA. Q-VECTOR CONVERGENCE WILL CONTINUE TO BE STRONG AS IT CROSSES THE AREA. Q-VECTORS CROSSING THE ISOTHERMS IMPLY A WEAKENING OF COLD FRONT. NUMEROUS SHOWERS AND THUNDERSTORMS ARE LIKELY OVERNIGHT...BECOMING SCATTERED BY SUNRISE. CLOUD COVER WILL BLANKET THE AREA LIMITING RADIATIONAL COOLING. THE MID LEVEL LOW WILL EDGE INTO WESTERN LAKE SUPERIOR ON THURSDAY. THE SURFACE LOW WILL VENTURE INTO NORTHERN WISCONSIN DRAGGING THE FRONT INTO CENTRAL U.P. THE THETA-E RIDGE AHEAD OF THE FRONT WILL PUSH INTO NORTHERN LOWER MICHIGAN. MOISTURE WRAPPING AROUND THE LOW WILL KEEP MEAN RELATIVE HUMIDITY HIGH ACROSS THE AREA. UPPER LEVEL WINDS STILL SHOWING WEAK DIVERGENCE ACROSS THE U.P. K-INDEX WILL BE AROUND 30. LIFTED INDEX WILL BE AROUND ZERO. Q-VECTORS STILL SUGGEST INSTABILITY OVER THE FORECAST AREA AND MORE FRONTOLYSIS. WILL KEEP SCATTERED THUNDERSTORMS AS THE INSTABILITY WILL WEAKEN...HOWEVER...THERE WILL CONTINUE TO BE ENOUGH MOISTURE TO FEED THE SYSTEM. THE CLOSED MID LEVEL LOW WILL REMAIN NEARLY STATIONARY OVER THE WESTERN U.P./LAKE SUPERIOR THURSDAY NIGHT. WEAK SHORTWAVE ENERGY WILL CYCLE THROUGH THE U.P. Q-VECTORS WILL REMAIN STRONG ENOUGH TO GENERATE MORE SHOWERS AND THUNDERSTORMS. THE SURFACE LOW WILL REMAIN OVER CENTRAL WISCONSIN. MOISTURE WRAPPING AROUND THIS LOW WILL FEED SHOWERS AND THUNDERSTORMS ACROSS THE AREA. A BLANKET OF CLOUDS WILL KEEP TEMPERATURES IN THE UPPER 50S. THE MID LEVEL LOW WILL REMAIN STATIONARY THROUGH FRIDAY AND FRIDAY NIGHT. Q-VECTORS WILL WEAKEN EVEN MORE OVER THE FORECAST AREA. THE THETA-E RIDGE WILL BE SOUTH OF THE FORECAST AREA. THE SURFACE LOW WILL BE OVER THE CENTRAL U.P. AND SOUTH CENTRAL LAKE SUPERIOR. A RIDGE SHIFTING INTO THE AREA WILL REDUCE THE CHANCE OF THUNDERSTORMS...BUT SHOWERS WILL CONTINUE. THE MID LEVEL RIDGE OVER THE ROCKIES WILL PUSH INTO THE NORTHERN HIGH PLAINS ON SATURDAY CAUSING THE LOW OVER WESTERN U.P./LAKE SUPERIOR TO MOVE INTO NORTHERN WISCONSIN. THE SURFACE FEATURES WILL CONTINUE WITH THE LOW OVER UPPER GREAT LAKES AND THE COLD FRONT PUSHING INTO MID MISSISSIPPI VALLEY. ISOLATE THUNDERSTORMS AND SCATTERED RAIN SHOWERS STILL SOUNDS REASONABLE. SHORTWAVE ENERGY WRAPPING AROUND THE MID LEVEL LOW WILL KEEP A CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS THE AREA. NONE. DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 331 AM CDT WED JUL 30 2003 FCST FOCUS ON APPROACHING SYSTEM TO AFFECT AREA THROUGH THE UPCOMING WEEKEND. MODEL CONSENSUS CONTINUES WITH TIMING AND VERY SLOW SPEED OF CLOSED UPR SYSTEM...AS IT DROPS SEWD FROM NR LAKE WINNIPEG OVER UPR MIDWEST THRU THE END OF THE WEEK AND OVER THE WEEKEND. INITIAL LINE OF SHRA AND TSTMS OVER ERN DKTAS/MN DIMINISHED AS BETTER UPPER DIVERGENCE SUPPORTING CONVECTION LIFTED NE INTO THE MN ARROWHEAD. FIRST SHOT OF PCPN DEVELOPING THIS MORNING IN WRN CWA...AND MOVING INTO THE EAST THIS AFTERNOON...ASSOC WITH LEAD SHRT WV TROF/VORT LOBE...ANALYZED OVER CNTRL MN AT 07Z RUC. LOBE WILL ROTATE INTO CNTRL WI BY 18Z AND ERN WI BY 00Z...WITH SUPPORTING UPR LVL DIVERGENCE LINGERING OVER THE EAST THRU 06Z. PCPN DEVELOPING ON ERN EDGE OF INCREASING SFC MOISTURE CONVERGING AHEAD OF SFC TROF...WITH MID 60 DEW POINTS EXPECTED TO CONTINUE TO FEED INTO SRN WI THRU THE MORNING. SFC TROF AND BEST MOISTURE CONVERGENCE LAG BEHIND THIS FIRST LOBE AND WILL PROVIDE FOCUS FOR SECOND BAND OF CONVECTION...AS AIRMASS DESTABILIZES LATE THIS AFTERNOON AND EVENING. BUFKIT FCST SNDGS FOR MSN AT 00Z SHOW CAPES NEAR 1300 J/KG AND -3 LI/S WILL GO LIKELY IN THE WEST THIS AFTERNOON. EAST DOES NOT HAVE AS GOOD A CHANCE TO DESTABILIZE SO WILL KEEP CHC POPS THERE. MODELS TAKE BULK OF THIS PCPN EAST OF CWA OVERNIGHT...THEN RE-FIRE THURSDAY AFTERNOON WITH INCREASING CYCLONIC FLOW AROUND UPR LOW AND STEEPENING MID LEVEL LAPSE RATES. DIFFICULTIES ABOUND BEYOND THUR AFTN TRYING TO TIME FORCING ASSOC WITH VORT MAXES ROTATING AROUND UPR LOW AS IT SLOWLY SINKS INTO... AND THRU WI DURING THE WEEKEND. GFS AND ETA...WHILE IN STRONG AGREEMENT WITH MOVEMENT OF UPR LOW CENTER THRU 84 HOURS...OUT OF PHASE BY 6 TO 12 HOURS WITH AFORE-MENTIONED VORTICITY MAXIMA. WILL CONTINUE WITH DIURNALLY DRIVEN PCPN IN CURRENT FCST THRU THE WEEKEND...AS 00Z GFS PLACES CENTER OF 500 MB LOW IN VCNTY OF LK WINNEBAGO AT 00Z MON. .MKX...NONE. $$ REM wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1030 AM EDT WED JUL 30 2003 FCST CONCERN THIS AFTN IS CONVECTION AND SVR POTENTIAL. WV IMAGERY SHOWS MIDLEVEL LOW OVER SE MANITOBA DRIFTING TOWARD NWRN MN. WARM CONVEYOR PCPN BAND EXTENDING FROM N OF LAKE SUPERIOR THRU THE WRN U.P. INTO WI HAS BEEN SLOWLY EDGING E THIS MORNING. RECENTLY...THIS PCPN HAS SHOWN A NOTICEABLE DIMINISHING TREND. EXPECT TSTM DEVELOPMENT JUST AHEAD OF THIS BAND DURING AFTN HEATING AND BEHIND IT WHERE CLOUDS ARE CLEARING OUT. ETA AND RUC FCST SOUNDINGS MODIFIED FOR T/TD OF 76/63F YIELD CAPE VALUES NEAR 2K J/KG. FORTUNATELY DEEP LAYER (0-6KM) SHEAR IS ONLY 10-20KT...LIMITING SIGNIFICANT STORM ORGANIZATION. HOWEVER...WET BULB ZERO HEIGHTS OF 9-10KFT WILL MAKE SVR HAIL A THREAT...AND FAVORABLE DECREASE OF THETA-E FROM SFC TO MIDLEVELS (NEAR OR EXCEEDING 20K) WILL PROVIDE POTENTIAL FOR STRONG WIND GUSTS. AREAS OVER THE CNTRL FCST AREA WHERE LAKE MICHIGAN LAKE BREEZE INTERSECTS POTENTIAL OUTFLOW FROM WRN U.P. SHRA WILL NEED TO BE WATCHED. ALTHOUGH ONGOING SHRA OVER WRN U.P. ARE DIMINISHING...NEW DEVELOPMENT SHOULD TAKE OFF SOON WHERE CLOUDS ARE THIN. GOING FCST IS GENERALLY IN GOOD SHAPE AND NO SIGNIFICANT CHANGES ARE PLANNED IN UPDATE. .MQT...NONE. ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BUFFALO NY 912 AM EDT WED JUL 30 2003 THE 12Z KBUF SOUNDING SHOWS LESS LOW LEVEL MOISTURE COMPARED TO YESTERDAY MORNING...BUT THE RUC DOES INDICATE SOME WEAK MOISTURE CONVERGENCE DEVELOPING ACROSS THE SOUTHERN TIER LATER THIS AFTERNOON. THIS WILL LEAD TO A FEW MORE CU ACROSS THIS AREA. THE HIGHER ELEVATIONS EAST OF LAKE ONTARIO WILL ALSO SEE A FEW MORE CU POPPING UP DURING THE AFTERNOON. OTHERWISE...THE REST OF THE AREA WILL SEE A LOT OF SUNSHINE WITH TEMPERATURES WARMING INTO THE LOWER 80S. STRENGTHENING SOUTHERLY FLOW FROM THE SURFACE UP THROUGH 850 MB DEVELOPING TONIGHT AND THURSDAY AS SURFACE HIGHS SHIFTS EAST OF THE AREA. GFS AND ETA BOTH SUGGESTING MINOR QPF FOR WESTERN SECTIONS BY LATE IN THE DAY THURSDAY. UPPER LOW STILL WELL UPSTREAM OVER THE WESTERN GREAT LAKES...SO NO SYNOPTIC SCALE FEATURES TO TRIGGER CONVECTION. ANY CONVECTION WILL HAVE TO DEVELOP ALONG A MESOSCALE BOUNDARY. RATHER WEAK LOW LEVEL FLOW SUGGESTING LAKE BREEZE CONVERGENCE BOUNDARY COULD SET UP BY LATE IN THE DAY. LOW CHANCE POPS LOOK REASONABLE WEST OF ROCHESTER WITH CAP STRENGTH WEAKENING AND INCREASE IN LOW LEVEL MOISTURE AND INSTABILITY. MODELS ARE IN AGREEMENT THAT THE FRIDAY THROUGH SUNDAY TIME PERIOD WILL BE UNSETTLED FOR THE AREA WITH MODEL SOUNDINGS SHOWING MOIST LOW LEVELS AND MODEST LAPSE RATES. UPPER LOW REMAINS NEARLY STATIONARY OVER THE GREAT LAKES THROUGH THE PERIOD. HARD AT THIS TIME TO PIN DOWN WHICH DAY WILL HAVE MORE CONVECTION THAN THE NEXT AS SEVERAL WAVES ROTATE AROUND LOW...BUT ALSO SEVERAL PERIODS OF "DRY SLOTTING" WILL ALSO OCCUR. THE UNSETTLED WEATHER LOOKS LIKE IT WILL REMAIN FOR MUCH OF NEXT WEEK AS WELL. MRF SUGGESTING UPPER LOW WILL SHIFT EAST AND MOVE OVER THE LOWER GREAT LAKES MONDAY THROUGH THURSDAY BEFORE LIFTING OUT. .BUF...NONE. $$ TJP/TMA ny AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PITTSBURGH PA 1023 AM EDT WED JUL 30 2003 RUC AND ETA MODELS SHOWING SOME MOISTURE INFLUX FROM THE SOUTHEAST THIS AFTERNOON. THIS ALONG WITH AN INVERTED TROF COULD KICK OFF SOME ISOLATED SHOWERS AND THUNDERSTORMS OVER THE SOUTHERN AND WESTERN PORTIONS OF THE REGION. LI VALUES ARE AROUND -1.5 OVER EAST CENTRAL OHIO AND IF WE START GETTING SOME AFTERNOON CONVECTION THEY COULD PRODUCE SOME STORMS. UPDATED THE ZONES TO ACCOUNT FOR THIS AND ALSO A FEW MORE CLOUDS OVERNIGHT. FCSTID = 66 PIT 83 63 82 64 / 10 10 40 50 HLG 83 63 81 64 / 10 10 40 50 MGW 83 63 81 64 / 10 10 40 50 ZZV 84 63 82 64 / 10 20 40 50 PHD 84 63 82 64 / 10 20 40 50 FKL 80 61 80 61 / 10 10 30 50 DUJ 80 61 80 61 / 10 10 30 50 LBE 83 63 81 64 / 10 10 40 50 BTP 80 61 80 61 / 10 10 30 50 IDI 83 63 81 64 / 10 10 40 50 ODM 80 60 79 62 / 10 10 30 50 .PBZ... MD...NONE. OH...NONE. PA...NONE. WV...NONE. $$ CAT pa INTERIOR CENTRAL CALIFORNIA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HANFORD CA 240 PM PDT WED JUL 30 2003 RADAR CONTINUES TO SHOW MORE SHOWERS AND THUNDERSTORMS DEVELOPING OVER THE SOUTHERN PARTS OF THE DISTRICT THIS AFTERNOON. RUC ANALYSIS IS SHOWING THIS AREA AS HAVING THE STRONGEST SURFACE MOISTURE FLUX CONVERGENCE THIS AFTERNOON. THEREFORE...WILL EXPECT CONVECTION TO CONTINUE OVER THE SOUTHERN HALF WITH MINIMAL DEVELOPMENT OVER THE NORTH. THIS HAS BEEN AND WILL CONTINUE TO BE A LOW PRECIP EVENT. THIS MORNINGS UPPER AIR OBSERVATIONS FROM DESERT ROCK SHOWS THE INVERTED-V PROFILE. MODELS SOUNDING OVER THE KERN DESERTS AND SOUTHERN SAN JOAQUIN VALLEY ALSO SHOW A SIMILAR PROFILE. YET...WIND HAS NOT BE A BIG FACTOR TODAY. HOWEVER...WILL CONTINUE WITH PREVIOUS THINKING OF THIS BEING A LOW QPF EVENT WITH ISOLATED GUSTY WINDS POSSIBLE. WATER VAPOR IMAGERY WITH RUC80 ANALYSIS CONTINUES TO SHOW THE REX BLOCK AXIS OVER CALIFORNIA WITH A STRONG EASTERLY FLOW PUSHING INTO THE DISTRICT. WITH LITTLE CHANGE EXPECTED IN THE NEXT 24 HOUR...WILL EXPECT FURTHER DEVELOPMENT THIS EVENING. THIS MORNING SHORT TERM MODEL PRODUCTION SHOWS THE BEST CONVECTIVE POTENTIAL OVER THE SIERRA NEVADA...KERN MOUNTAINS AND SOUTHERN SAN JOAQUIN VALLEY. WHILE SOME INSTABILITY WAS NOTED OVER THE CENTRAL SAN JOAQUIN THIS MORNING...MODELS ADVECT MORE STABLE AIR INTO THE CENTRAL SJV FROM THE NORTH. THIS ADVECTION WILL MINIMIZE ANY FURTHER DEVELOPMENT THIS EVENING...YET WILL NOT RULE OUT ANY THUNDERSTORMS FROM DRIFTING TOWARDS MERCED COUNTY. MODELS SEEM A BIT TO AGGRESSIVE AT TERMINATING THE CONVECTIVE DEVELOPMENT INTO THURSDAY. WITH LITTLE MOVEMENT IN THE BLOCKING PATTERN...WILL EXPECT ADDITIONAL MONSOONAL MOISTURE TO ADVECT ACROSS THE DISTRICT TONIGHT AND THURSDAY. THEREFORE...WILL BACK OFF THE MODELS ATTEMPT TO INTRODUCE A DRY WEDGE OF AIR IN FROM THE SOUTH ON THURSDAY. WILL EXPECT A REPEAT OF TODAY EVENTS ON THURSDAY AND SLOW THE DRYING MORE TOWARDS FRIDAY. MODELS ARE STARTING TO THE UPPER LOW LIFTING NORTH ON FRIDAY AND ALLOWING THE FLOW TO BECOME MORE SOUTHERLY. AT WHICH TIME...WILL EXPECT THE PRECIP TO RETREAT BACK INTO THE MOUNTAINS. CURRENT TREND IS TO SLOWING DECREASE THE COVERAGE OF SHOWERS AND THUNDERSTORMS THROUGH OUT THE SHORT TERM PERIOD INTO THE EXTENDED. THE FLOW DOESN/T TRULY BECOME SOUTHWESTERLY UNTIL WELL INTO THE EXTENDED...AT WHICH TIME MUCH OF THE DISTRICT BEGINS TO DRY OUT. FOR THE EXTENDED FORECAST PERIOD SUNDAY THROUGH WEDNESDAY...MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT THROUGH MONDAY. DRIER SOUTHWESTERLY FLOW ALOFT SHOULD PREVAIL OVER THE AREA AS THE MID/UPPER HIGH CONTINUES ITS RETREAT SOUTHEASTWARD FROM THE GREAT BASIN AREA AND A SHORTWAVE TROUGH TRACKS NORTHEAST ACROSS CENTRAL CALIFORNIA. FOR SUNDAY...ONLY ISOLATED CONVECTION OVER THE SIERRA CREST IS EXPECTED. BY MONDAY A DEEPENING PACIFIC TROUGH SHOULD APPROACH THE NORTHWEST US COAST. THE GFS IS MOST AGGRESSIVE DEEPENING THE TROUGH AND BRINGING IT ASHORE BY TUESDAY...WHILE THE ECMWF LAGS FAR BEHIND. FORECAST IS GENERALLY BETWEEN THE TWO SOLUTIONS. STRONGER ONSHORE FLOW THROUGH THE PERIOD IS A GOOD BET...WITH TEMPERATURES REMAINING SEVERAL DEGREES COOLER THAN RECENT READINGS AND DRY CONDITIONS PREVAILING OVER THE ENTIRE DISTRICT. .HNX...NONE. $$ MOLINA/BAGNALL ca INTERIOR CENTRAL CALIFORNIA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HANFORD CA 930 AM PDT WED JUL 30 2003 MONSOON WELL IN PLACE THIS MORNING AS SHOWERS AND THUNDERSTORMS MOVE THROUGH THE CWFA. DOPPLER RADAR SHOWING MUCH OF THE ACTIVITY OVER THE SOUTHERN HALF OF THE DISTRICT WITH A FEW ISOLATED CELLS MOVING THROUGH THE NORTHERN HALF. PRECIP VALUES REMAIN LOW...EVEN WITH A MORE TROPICAL AIRMASS STREAMING THROUGH THE AREA...AS MOST REPORTING STATIONS CAME IN WITH READING OF LESS THAN A TENTH OF AN INCH. ONE FACTOR BEING THAT THE AIRMASS COLUMN REMAINS WARM TODAY... AND NOT ALLOWING THE LOWER LEVELS TO GET WELL SATURATED. THIS MORNINGS AND YESTERDAY AFTERNOONS SOUNDING FROM DESERT ROCK AND EDWARDS AFB...UPSTREAM...SHOWED AN INVERTED-V PROFILE WITH A WEAK LOWER LEVEL WIND PROFILE. THEREFORE...DOWNBURST POTENTIAL A BIGGER FACTOR THAN HEAVY RAIN THIS AFTERNOON. LOOKING AT THE BIGGER PICTURE...WATER VAPOR AND RUC ANALYSIS SHOWING THE HIGH OVER LOW... REX BLOCK PATTERN...WITH A STRONG EASTERLY FLOW OVER THE DISTRICT. RUC DID PICK UP ON A VORT MAX...IN-PHASE WITH THE SATELLITE ENHANCEMENT...THAT MOVED THROUGH THE CWFA LAST NIGHT. THIS PIECE OF ENERGY ALLOWED THUNDERSTORM DEVELOPMENT TO CONTINUE OVERNIGHT AND IS NOW PUSHING OFFSHORE. WILL EXPECT A LITTLE RELIEF THIS MORNING AS THE NEXT VORT MAX EXPECTED TO MOVE IN BY 4:00 PM TODAY. NO UPDATED NEEDED AT THIS TIME AS SITUATION HANDLED WELL WITH CURRENT FORECAST PACKAGE. .HNX...NONE. $$ MOLINA ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 120 PM EST WED JUL 30 2003 FORECAST CHALLENGE WILL CONTINUE TO BE CHANCES AND TIMING OF PRECIP. SFC ANALYSIS SHOWS LOW PRESSURE IN SOUTHERN CANADA JUST NORTH OF MN AND STATIONARY FRONT EXTENDING FROM THE CAROLINAS ACROSS THE TN VALLEY AND OVER TO OK. KLOT RADAR SHOWING A FEW SH/TSRA OVER NORTHERN IL/SOUTHERN WI IN AREA OF GREATER INSTABILITY WHERE CAPES ARE OVER 1200J/KG AND LI'S ARE AROUND -2 WHILE AIRMASS OVER OUR CWA REMAINS QUITE STABLE. 15Z RUC INDICATES LITTLE EASTWARD PROGRESSION WITH THE INSTABILITY TO OUR WEST SO NOT ANTICIPATING ANY CONVECTION MAKING ITS WAY INTO OUR AREA THIS EVENING. CLOSED UPPER LOW STACKED ABOVE SFC LOW IN SOUTHERN CANADA WILL DO VERY LITTLE OVER NEXT 48HRS...SLIDING SLOWLY SE INTO ARROWHEAD OF MN. FRONTAL WAVE WILL MOVE ALONG STATIONARY FRONT TO THE SOUTH AND NUDGE UP TOWARD OH VALLEY ON THU. THIS WILL HAVE OUR AREA CAUGHT A LITTLE BIT BETWEEN SYSTEMS ON THU. MOISTURE AND LIFT ASSOICATED WITH FRONTAL WAVE WILL TRY TO WORK INTO SE CWA WHILE GOOD AXIS OF INSTABILITY FORMS TO OUR WEST OVER IL BY THU AFTERNOON. WILL BACK OFF SLIGHTY WITH PRECIP CHANCES BY KEEPING THU AM DRY BUT WILL CONTINUE 30 POP FOR THE AFTERNOON AS SYSTEMS ARE CLOSE ENOUGH AND AIRMASS DOES DE-STABLIZE WITH CAPES GETTING TO AROUND 1500J/KG AND LI'S OF -2. WILL CONTINUE SMALL CHANCE INTO THU EVENING BUT KEEP OVERNIGHT HOURS DRY. BETTER CHANCES OF PRECIP WILL FOLLOW ON FRI AND SAT AS SFC LOW DROPS DOWN INTO GREAT LAKES REGION AND STALLS FRONT OUT OVER OUR AREA. NOT MUCH ADJUSTMENT TO CURRENT TEMP FCST. GUIDANCE NUMBERS CLOSE AND REASONABLE AS TEMPS SHOULD STAY NEAR OR SLIGHTLY ABOVE NORMAL THROUGH THE PERIOD. GFS INDICATING CHANCE OF SHOWERS/STORMS THROUGH THE EXTENDED AS UPPER LOW AND SURFACE LOW DRIFT AROUND THE GREAT LAKES...THOUGH MOISTURE NOT OVERLY IMPRESSIVE AS NARROW EXTENSION OF BERMUDA HIGH REACHES WESTWARD ACROSS THE GULF. GEM SHOWS A SIMILAR SCENARIO SUN/MON...BUT THEN MOVES THE LOW PRESSURE SYSTEM OFF TO THE NORTHEAST TUES/WED. GFS GENERALLY HAS DRY NIGHTS WITH AFTERNOON SHOWER/STORM DEVELOPMENT MONDAY THROUGH WEDNESDAY. HOWEVER WITH CURRENT DRY FORECAST AND SOME UNCERTAINTY IN THE OUTER PERIODS...WILL RESTRICT CHANCE OF RAIN TO SUNDAY/MONDAY WITH BEST MOISTURE AND DYNAMICS AND BETTER MODEL AGREEMENT. .IWX... IN...NONE. MI...NONE. OH...NONE. $$ JAL/TAR in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1100 AM EDT WED JUL 30 2003 LATEST SAT PICS SHOWING MOSTLY CLEAR SKIES ACROSS THE AREA AS E-W ORIENTED SFC RIDGE DOMINATING THE WX ACROSS MOST OF ILN FA. WEAK BDRY LYR TROUGH CURRENTLY EXTENDING NE INTO WV EXPECTED TO PIVIT SLOWLY NW DURING THE DAY. EXPECT AT MOST ISOLATED CONVECTION TO DEVELOP WITHIN THIS TROUGH AXIS LATER TDY. WITH OVERALL FORCING RATHER NEGLIGABLE IN OUR AREA...FEEL CONVECTIVE TEMP WILL NEED TO BE MET FOR ANY DEVELOPMENT. BEST LOCATION IN OUR AREA FOR THIS WILL BE EXTREME SE PORTION OF ILN FA. SO THE 10 POPS IN THE CURRENT GRIDS ARE FINE. LATEST 12Z ETA NOW MORE IN LINE WITH THE EARLIER RUC WITH HOLDING DOWN THE NW PROGRESS OF THIS FEATURE. THIS MAY HELP KEEP ANY CONVECTION ESE OF ILN FA TDY. NO ZONE UPDATES AT THIS TIME. .ILN...NONE. JTD oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 333 PM CDT WED JUL 30 2003 MAIN EMPHASIS OF THIS FORECAST WAS PLACED IN THE SHORT TERM... TONIGHTS CONVECTIVE THREAT AND EVOLUTION INTO THURSDAY NIGHTS FRONTAL PASSAGE. CURRENT SURFACE PATTERN IS FAIRLY COMPLEX AND IS NOT STRONG IN ITS FORCING. A WEAK SURFACE CONVERGENCE BAND IS LOCATED ALONG THE TROUGH BOUNDARY WHICH LIES FROM KMDZ-KDEH AT 20Z. WITH CAPES NEAR 2-3000 J/KG THE ATMOSPHERE IS READY TO CONVECT. THE MID-UPPER LEVELS ARE SOMEWHAT SUBSIDENT WHICH IS NOT THE GREATEST SUPPORT FOR TSRA. HOWEVER...FURTHER NORTH ON THE POLEWARD SIDE OF THE JETSTREAM...VERTICAL MOTION IS A BIT MORE ENHANCED /NRN WI/. SPC HAS ISSUED A WATCH FOR THIS AREA THORUGH 8PM. 0-6KM BULK SHEAR VALUES PER RUC INDICATE INCREASING TRENDS INTO THE OVERNIGHT HOURS...BUT STILL BELOW SUPERCELL MODES. BOTH THE 12Z GFS AND ETA HAD TROUBLES WITH THE MORNING VORTICITY DETAILS AND RIDGING OVER THE GREAT LAKES BUT BOTH COME TO A SIMILAR SOLUTION THROUGH THE PERIOD BY 12+HOURS. TONIGHT THE INSTABILITY AND BOUNDARY WILL REMAIN AND CHANCES OF TSRA WOULD CONTINUE THROUGH THE EVENING. THE TROUGH BOUNDARY SHOULD BEGIN TO LIFT NORTHWARD LATE TONIGHT OR WASH OUT. THIS IS IN RESPONSE TO THE MAIN SURFACE LOW ASSOCIATED WITH UPPER LOW OVER SRN CANADA SHIFTS SOUTH. THERE IS AN ISOLATED CHANCE OF SEVERE WEATHER /HAIL OR WIND/...MAINLY OVER NRN WI. WILL HAVE SCT TSRA WORDING ELSEWHERE ON AND EAST OF THE BOUNDARY. MODELS DEPICT THE CURRENT SURFACE FRONT NEAR LAKE WINNIPEG TO TAKE A HARD SHIFT SOUTHWARD TOWARD THE FORECAST AREA ON THURSDAY. SURFACE WINDS WILL BACK AROUND TO SOUTH IN RESPONSE TO PRESSURE FALLS OVER MN THURSDAY. BOTH MODELS AGREE ON WESTERLY LOW-LEVEL WARM ADVECTION AHEAD OF THIS SHORTWAVE AND FRONT. OVERALL THERE IS WEAK FORCING AND JUST INSTABILITY ON THURSDAY SO HAVE ELECTED TO WARM THE HIGHS WITH FEWER CLOUDS. ALSO REDUCED THE CHANCE OF RAIN AS LITTLE FORCING IS APPARENT. THERE IS A SMALL CHANCE OF CONVECTION ACROSS THE NORTH LATER THURSDAY BUT THE MAIN SHOW WOULD BE THURSDAY NIGHT. QG FORCING IS DEEPER AND MODERATE WITH LOW-LEVEL MOISTURE TRANSPORT INDICATED IN THE LOW-LEVEL JET ACROSS IOWA AS WELL. THIS IS CONVERGENT INTO THE SOUTHERN FORECAST AREA. SBCAPE SHOULD RESPOND TOO ACROSS THE FORECAST AREA WITH 2-3000 J/KG ACROSS THE AREA FOR EARLY EVENING AS THE FRONT MOVES CLOSER. SPC HAS A SLIGHT RISK FOR THIS FRONT WHICH LOOKS FINE. HOWEVER...WIND SHEAR VALUES ARE ONLY AROUND 30 KTS /0-6 BULK SHEAR/...SO SUPERCELLS WILL NOT BE AROUND. HAVE INCREASED THE CHANCE OF RAIN TO 50 PERCENT AREAWIDE. THE FRONT WILL INTO WI BY EARLY FRIDAY AND EXIT FRIDAY AFTERNOON SO RAIN CHANCES WHERE TIMED IN THIS MANNER. THUS...CONFIDENCE IS HIGHEST IN MEASURABLE RAIN OVERNIGHT THURSDAY. DEEP LOW PRESSURE WILL THEN INFLUENCE THE AREA FROM SATURDAY ON. EXTENDED...FROM SATURDAY TO WED THE LOW WILL BE OVER THE GREAT LAKES AND THESE RUNS //12Z/29 ECMWF AND 00Z GFS// ARE SLOWER ON MOVING IT EAST AND FURTHER SOUTH WITH IT. CURRENT VISIBLE IMAGE OVER SOUTHERN CANADA IS A VISION OF THINGS TO COME FROM THIS SYSTEM. THUS...DETAILS ARE HARD TO COME BY IN THIS SCENARIO AND ARENT PRUDENT. AFTERNOON AND EVENING TSRA/SHRA ARE THE BEST BET WITH LESS CLOUDS AND LOWER RAIN CHANCES OVERNIGHT AND EARLY MORNING HOURS. HAVE LOWERED THE HIGHS ABOUT 5F SAT/SUN WITH POOL OF COLDEST AIR /11-12C AT 850MB/ OVER THE AREA. HAVE TRIED TO LEAVE WED WITHOUT A CHANCE OF RAIN AS LOW SHIFTS EAST. .LSE...WATCHES/WARNINGS/ADVISORIES...NONE. $$ BAUMGARDT wi