AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 339 PM MDT FRI AUG 24 2007 .SHORT TERM... (TNGT AND SAT) TSTM COVERAGE AND INTENSITY THE MAIN CHALLENGE LATE THIS AFTN AND EVE ALONG WITH THE POTENTIAL DEVELOPMENT OF IFR-MVFR STRATUS/FOG ACROSS THE LOWER AR RIVER VALLEY LATE TNGT-SAT MORNING. CURRENTLY...LATE MORNING/EARLY AFTN HAND-ANALYZED SURFACE CHART SHOWED OLD STATIONARY FRONTAL BOUNDARY WAS ALONG THE ERN CO MOUNTAINS AND TRAILING INTO NERN NM AND PANHANDLES OF OK/TX. SURFACE DEW POINTS IN THE 50S/60S ACROSS ERN CO...AS THE BKN-OVC IFR-MVFR STRATUS/FOG BURNED OFF BY MIDDLE TO LATE MORNING ACROSS PARTS OF SERN CO....BUT IS STILL HANGING ON NEAR THE KS/CO BORDER THIS AFTN. RATHER SIGNIFICANT UPPER LEVEL SHORTWAVE TROUGH MOVING THROUGH THE CNTRL ROCKIES PER H5-H3 LAYER VORTICITY AND H3-H2 POTENTIAL VORTICITY POSITIVE VALUE LOBE RUC ANALYSES. MIDLEVEL CYCLONIC SHEAR AXIS WAS ALONG THE I-25 CORRIDOR AROUND NOON. SUBSTANTIAL SUBSIDENCE FLOW BEHIND THE SYSTEM AS WATER VAPOR IMAGERY SHOWING SOME DRYING ALOFT AND VISIBLE/IR SATELLITE IMAGERY DATA BARELY SHOWING ANY CLOUD DEVELOPMENT ACROSS THE GREAT BASIN AND CO MOUNTAINS/VALLEYS...EXCEPT FOR FEW-SCT CU OVER THE SWRN MOUNTAINS. LOOKING OUT THE WINDOW... EARLY THIS AFTN...THERE ARE A COUPLE OF CU FORMING OVER OUR ERN MOUNTAINS...BUT VERTICAL DEPTH IS VERY LIMITED AND LENDING MORE TOWARDS STRATO-CU. MODERATE TO TOWERING CU DEVELOPMENT IS WAY BEHIND CLIMATOLOGY RIGHT NOW...SO NOT SURE HOW MUCH SHOWER/TSTM WILL FORM OVER THE MOUNTAINS...EXCEPT AROUND THE NM-CO BORDER. STILL...THERE IS RESPECTABLE SURFACE-BASED CAPE VALUES OF 500-2000 J/KG ACROSS THE AREA...BUT CONVECTIVE INHIBITION IS WINNING OUT ACROSS THE SERN CO PLAINS DESPITE A SYNOPTIC SCALE SYSTEM OVERHEAD. AROUND 1950Z... FIRST CELL WENT UP JUST NE OF KTAD IN LAS ANIMAS COUNTY. LATE THIS AFTN AND TNGT...CHALLENGING FORECAST FOR THE NEXT 6-12 HOURS. THE AFOREMENTIONED SHORTWAVE TROUGH WILL BE EXITING ERN CO BY EARLY THIS EVE WITH SUBSIDENT FLOW OVER MUCH OF CO TNGT. MY FEELING IS THE GREATER THREAT FOR SHOWER/TSTM DEVELOPMENT WOULD BE JUST N OF THE STATIONARY FRONT WHICH IS ACROSS NERN NM-OK/TX PANHANDLES. REGIONAL RADAR SHOWING ISOLD-SCT SHRA/TSRA FORMING OVER NERN NM AND THIS IS PROBABLY THE INITIATION-ZONE...ALONG NM/CO BORDER AND SWD. THERE STILL IS THE POTENTIAL FOR A FEW CELLS TO GO ACROSS EXTREME SERN CO...IF THE LOW LEVEL CAPPING INVERSION CAN BE BROKEN BY THE EXITING SHORTWAVE TROUGH LATE THIS AFTN AND EARLY EVE. CONVECTIVE PARAMETERS STILL SUGGESTING THE POTENTIAL FOR STRONG-SEVERE TSTMS ACROSS LAS ANIMAS AND BACA COUNTIES. IF ALL CONDITIONS CAN COME TOGETHER AND TSTM CELLS GET ANCHORED ON A BOUNDARY...THERE COULD BE A TORNADO ACROSS LAS ANIMAS AND BACA COUNTIES GIVEN THE LAPS AND NAM12 LAYER SIGNIFICANT TORNADO PARAMETERS ARE POINTING TOWARDS ERN LAS ANIMAS AND BACA COUNTIES FOR A NEAR TERM TORNADO THREAT AREA. POTENTIAL FOR ISOLD-SCT SHOWERS/TSTMS TO EVOLVE INTO A NOCTURNAL MESOSCALE CONVECTIVE SYSTEM ACROSS EXTREME SERN CO-NERN NM-OK/TX PANHANDLES. THIS IS IN RESPONSE TO A WEAK(15-20KTS) H85-H8 LOW LEVEL JET STREAK DEVELOPING AND MOISTURE/THERMAL POSITIVE ADVECTION PROCESSES LEADING TO LIFT AND DESTABILIZATION ON THE N SIDE OF THE STATIONARY FRONT. STILL COULD NOT RULE OUT ONE OR TWO CELLS TO FORM OVER THE MOUNTAINS AND I-25 CORRIDOR...BUT THE PROBABILITY LOOKS PRETTY LOW. MESOSCALE MODELS ARE SUGGESTING THE POSSIBILITY OF IFR-MVFR STRATUS/FOG TO FORM OVER THE LOWER AR RIVER VALLEY AFTER MIDNIGHT...ESPECIALLY IF IT RAINS. SFC-PBL LAYER HUMIDITIES ARE PROGGED TO BE 85-100 PERCENT. THINK THE THERMAL/TERRAIN DRAINAGE WINDS OFF THE PALMER DIVIDE SHOULD KEEP ANY STRATUS OUT OF THE COLORADO SPRINGS AREA...BUT COULD FORM/ADVECT INTO THE PUEBLO AREA JUST AROUND SUNRISE. SAT...SCT-BKN IFR-MVFR STRATUS/FOG MAY BE ACROSS THE SERN CO PLAINS AND SHOULD BURN OFF BY MIDMORNING...IF IT FORMS. HARD PRESSED TO FIND A SIGNIFICANT WEATHER FEATURE ALOFT TO ENHANCE THE DIURNAL CONVECTIVE ENERGY AVAILABLE SAT AFTN. STILL COULD NOT RULE OUT SOMETHING FORMING OVER THE MOUNTAINS AND DRIFTING INTO THE ADJACENT VALLEYS/PLAINS...ESPECIALLY ALONG NM/CO BORDER. SPC DAY 2 HAS MUCH OF SERN CO OUTLOOKED FOR SLIGHT RISK GIVEN THE NW FLOW ALOFT JUXTAPOSED WITH LOW LEVEL ELY FLOW. THIS CERTAINLY SEEMS POSSIBLE GIVEN ADEQUATE VERTICAL SHEAR...CONVECTIVE AVAILABLE POTENTIAL ENERGY OF 1K-3K J/KG...AND SURFACE BASED INSTABILITY. MAIN THREAT WOULD BE STRONG WIND GUSTS AND LARGE HAIL WITH THE POSSIBLE ROTATING STORMS. METZE .LONG TERM... (SATURDAY NIGHT THROUGH FRIDAY) STILL LOOKS ABOUT THE SAME AS PREVIOUS RUNS. UPPER HIGH PRESSURE WILL BUILD OVER COLORADO BRIEFLY THIS WEEKEND TO BRING BRIEF WARMING/DRYING. STORMS WILL TEND TO BE ISOLATED SATURDAY NIGHT AND MOST OF SUNDAY. TEMPERATURES WILL BE ABOVE AVERAGE WITH HIGHS WELL INTO THE 90S ON THE PLAINS (HOT). THEN...AS SUNDAY PROGRESSES...SUBTROPICAL MOISTURE WILL WORK UP THE BACKSIDE OF THE RIDGE...WRAPPING INTO COLORADO FROM THE SOUTHWEST. CONSEQUENTLY...THUNDERSTORM CHANCES WILL GO UP AGAIN...AND TEMPERATURES WILL DROP BACK A LITTLE (ALTHOUGH REMAINING ABOVE AVERAGE). THIS PATTERN PERSISTS INTO TUESDAY. NEXT POSSIBLE SIGNIFICANT SYSTEM TO COME THROUGH LOOKS TO ARRIVE TUESDAY NIGHT...PERSISTING THROUGH THURSDAY BEFORE WARMING/DRYING STARTS AGAIN. THE SYSTEM APPEARS TO BE THE RESULT OF SUBTROPICAL MOISTURE ROUNDING THE TOP OF THE RIDGE COLLIDING WITH A PASSING NORTHERN STREAM SHORTWAVE. THE MOISTURE FROM THE SOUTH...INTERACTS WITH THE NORTHERN SURFACE BOUNDARY TO ORGANIZE CONVECTION AND SEND IT SOUTH INTO EASTERN COLORADO. THE EASTERN PLAINS THEN REMAIN UNDER MOIST UPSLOPE FLOW FOR A COUPLE DAYS BEHIND THE FRONT. SO...IF ALL THIS PANS OUT...WE MAY END UP WITH A COUPLE MORE DAYS OF WIDESPREAD CONVECTIVE RAINS. ADDITIONALLY...DEPENDING ON FRONTAL INTENSITY AND WIND SHEAR PROFILES...COULD BE LOOKING AT MORE SEVERE WEATHER TOO. AS ALWAYS...STAY TUNED. LW && .AVIATION... ISOLD SHOWERS/TSTMS COULD AFFECT KALS...KCOS...AND KPUB AIRPORT TERMINAL AREAS WITH MVFR CEILINGS...BRIEF WIND GUSTS UP TO 35KTS/ERRATIC WINDS...AND SMALL HAIL UNTIL 02Z...BUT THE PROBABILITY IS PRETTY LOW(5-15 PERCENT). KALS AND KCOS WILL HAVE NEARLY VFR CLEAR CONDITIONS DEVELOPING AFTER 03Z AS RELATIVELY DRIER AIR MOVES IN ALOFT AND KCOS THERMAL/TERRAIN NELY DRAINAGE WINDS DEVELOP AFTER MIDNIGHT. SOME IFR-MVFR STATUS/FOG COULD DEVELOP ACROSS THE KPUB TERMINAL AREA...AND SERN CO PLAINS BETWEEN 06Z/25-17Z/25. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 17/50 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 222 PM MDT FRI AUG 24 2007 .SHORT TERM (TONIGHT THROUGH SUNDAY)... AIR MASS HAS STABILIZED BEHIND DEPARTING COLORADO TROUGH. SHALLOW CONVECTION NOTED ON THE 1930Z VISIBLE IMAGERY...BUT THESE CLOUDS ARE CAPPED FROM DRY SUBSIDENT AIR. THE LATEST RUC MODEL INDICATES A FEW SHOWERS WILL FORM NEAR THE DIVIDE INCLUDING THE SAN JUAN MOUNTAINS LATE THIS AFTERNOON. SO WILL KEEP A MENTION OF ISOLATED STORMS THROUGH EARLY EVENING...BUT ANY STORMS THAT DO OCCUR WILL END AT SUNSET AS THERE IS NO UPPER AIR SUPPORT. SATURDAY...SUBTROPICAL HIGH STRENGTHENS OVER THE FOUR CORNERS AREA WITH WARMING TEMPERATURES ALOFT...MEANING MOSTLY SUNNY CONDITIONS CONTINUE FOR ANOTHER DAY. THE LACK OF MOISTURE AND SUBSIDENCE WILL CAP AFTERNOON CONVECTION OVER THE HIGH TERRAIN...EXCEPT FOR THE SAN JUAN MOUNTAINS WHERE LAPSE RATES WILL BE STEEPER FOR POP AND DROP ISOLATED STORMS. CHANGES WILL BE UNDERWAY ON SUNDAY AS EASTERLY WAVES (INCLUDING REMNANT MOISTURE FROM WHAT WAS HURRICANE DEAN) CIRCULATE AROUND THE SUBTROPICAL HIGH INTO ARIZONA. MID TO HIGH CLOUD WILL BE SPREADING FROM THE SOUTH BY SUNDAY AFTERNOON. THE 12Z MODEL DATA DID NOT INDICATE MUCH CONVECTIVE POTENTIAL ON SUNDAY AFTERNOON...IN SPITE OF THE MOISTURE INCREASE WITH PRECIPITABLE WATER EXCEEDING ONE INCH OVER SE UTAH. THE DEEPER MOISTURE HOLDS OFF UNTIL AFTER THE SHORT TERM PERIOD. THE FORECAST GRIDS WILL INDICATE AN INCREASE OF CLOUD COVER WITH SLIGHT CHANCE POPS FOR THE SOUTHERN ZONES. .LONG TERM...SUNDAY NIGHT THROUGH FRIDAY... MAIN AREA FOR FOCUS FOR THE EXTENDED IS THE POSSIBILITY OF SUB TROPICAL MOISTURE...REMNANTS FROM DEAN...BEING PULLED OVER EASTERN UT AND WESTERN CO. SLIGHT VARIATION IN TIMING OF THE MOISTURE PUSH BETWEEN MODELS AND INDIVIDUAL MODEL RUNS WITH THE BEST CONSENSUS BEING SUNDAY EVENING FOR THE DEEPER MOISTURE TO FLOW OVER THE SOUTHERN PORTION OF THE FORECAST AREA. HAVE INCREASED POPS SLIGHTLY TO TREND TOWARD THIS INFLUX BUT NOT READY TO JUMP CATEGORIES YET. ALSO INCREASE CLOUD COVER FOR THE SUNDAY NIGHT THRU MONDAY PERIOD. MOISTURE WILL LINGER THROUGH MONDAY AS UPPER LEVEL DISTURBANCES ALSO ROTATE OVER THE REGION. THE RIDGE BEGINS TO BUILD OVER THE FOUR CORNERS REGION TUESDAY WITH RESIDUAL MOISTURE HELPING WITH AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS. THE RIDGE EXPANDS TO THE WEST WITH THE CENTER SETTING UP SOUTHWEST OF OUR CWA...WHICH WILL LEAVE PORTIONS OF THE CENTRAL AND NORTHERN MTNS IN WEAK NORTHWEST FLOW ALOFT BY MID WEEK. EXPECT A SLIGHT WARMING TREND WITH DIURNAL CONVECTION FOR THE MIDDLE TO END OF THE WEEK. && .AVIATION... ISOLATED SHORT LIVED THUNDERSTORMS OVER THE ROCKY MOUNTAINS OF WESTERN COLORADO UNTIL 03Z...OTHERWISE VFR CONDITIONS WITH MOSTLY CLEAR CONDITIONS. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...NONE. .UT...NONE. $$ SHORT TERM...PF LONG TERM...AS AVIATION...PF co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 322 PM MDT THU AUG 23 2007 .SHORT TERM... (TONIGHT AND FRIDAY) MAIN SHORTWAVE TROF IS MOVING INTO NW CO ATTM WITH ASSOC 70 KT UPPER JET EXTENDING ACROSS NRN CO. FRONTAL BOUNDARY IS STILL LYING ALONG/JUST NORTH OF THE CO/NM BORDER. THUNDERSTORMS ARE BEGINNING TO FIRE ALONG THE NRN FRONT RANGE AHEAD OF THE TROF...AND ALONG THE FRONTAL BOUNDARY ACROSS SRN LAS ANIMAS COUNTY. SFC DEW POINTS HAVE BEEN INCREASING ACROSS SE CO BEHIND THE BOUNDARY...WITH VALUES RANGING FROM THE MID 50S TO LOWER 60S. WITH SHORTWAVE TROF APPROACHING FROM THE WEST...BOTH NAM AND RUC (WHICH DIDN/T INITIALIZE WELL WITH THE FRONTAL POSITION IN 12Z RUNS) BOTH INDICATE FALLING SFC PRESSURES ALONG THE SRN BORDER...WITH FRONT LIFTING BACK TO THE NORTH DURING THE AFTN AND STALLING ALONG THE PALMER DIVIDE BY LATE AFTN. LATEST MSAS PRESSURE CHANGE CHARTS ARE STARTING TO INDICATE SOME FALLING SFC PRESSURES SOUTH OF PUEBLO...SO THIS MAY INDEED BE OCCURRING...BUT THINK THAT FRONTAL BOUNDARY WILL END UP BEING MUCH FARTHER SOUTH THAN THE 12Z NAM12 AND RUC RUNS SUGGESTED. 18Z RUC4/NAM12 RUNS SEEM TO HAVE FINALLY LATCHED ON TO FARTHER SOUTH FRONTAL POSITION KEEPING IT ALONG THE SRN TIER COUNTIES THROUGH THE AFTN WHICH LOOKS MORE REASONABLE. NORTH OF THIS BOUNDARY SBCAPES ARE 1500-2000 J/KG WITH DEEP LAYER SHEARS OF 40-55 KTS...WHICH WOULD SUPPORT SUPERCELL THUNDERSTORMS WITH LARGE HAIL AND DAMAGING WINDS THE MAIN THREAT. LATEST 18Z RUNS SUGGEST MORE CIN ACROSS THE EASTERN COUNTIES THAN PREVIOUS RUNS SUGGESTED...BUT WITH APPROACHING TROF...UPPER LIFT SHOULD BE SUFFICIENT TO BREAK THE CAP EVENTUALLY...THOUGH TIMING OF UPPER TROF WOULD SUGGEST A LATER START TO CONVECTION/SEVERE POTENTIAL FARTHER EAST. SO SVR THREAT WILL INITIALLY START OUT ALONG THE EASTERN SLOPES OF THE SE MTS AND ALONG THE SRN BORDER AFTER 21Z...THEN SPREAD INTO THE ADJACENT PLAINS DURING THE LATE AFTERNOON/EVENING. WITH LOW LVL WINDS BECOMING MORE EASTERLY...0-1KM HELICITIES MAY APPROACH AROUND 80-120 M2/S2 ACCORDING TO 18Z RUC AND NAM ALONG THE EASTERN SLOPES OF THE SE MTS. SO CAN/T RULE OUT AN ISOLATED TORNADO...ESP ALONG THE PALMER DVD WHERE T/TD SPREADS MAY BE AROUND 20-25 DEGREES OR LESS. HOWEVER...TORNADO THREAT IS LOOKING LESS LIKELY ELSEWHERE. THUNDERSTORMS CONGEAL INTO AN MCS ACROSS EC CO AFTER 03Z WHICH MOVES EASTWARD INTO KANSAS AFT MIDNIGHT. WITH UPPER TROF TRAILING ACROSS CO OVERNIGHT...KEPT POPS GOING THE MAJORITY OF THE NIGHT ACROSS THE AREA. BUMPED UP POPS ACROSS THE SE PLAINS DURING THE EVENING. FOR FRIDAY...UPPER TROF WILL BE MOVING EAST OF THE AREA...WITH SUBSIDENCE ALOFT. MODEL SOUNDINGS ARE LOOKING FAIRLY CAPPED ACROSS THE FAR SE PLAINS...AND AM HARD PRESSED TO FIND ANY SHORTWAVES TO PROVIDE MUCH FORCING. HOWEVER...EASTERLY UPSLOPE FLOW...DEW POINTS IN THE MID 50S TO LOWER 60S...YIELD SOME HEALTHY CAPES OF 2000-3000 J/KG ALONG THE EASTERN SLOPES OF THE SE MTS. 0-6 KM SHEARS STILL AROUND 30-35 KTS...SO ANOTHER POTENTIAL FOR SEVERE THUNDERSTORMS EXPECTED ON FRIDAY...MOSTLY CONFINED TO THE EASTERN MTS/ADJACENT PLAINS. HAVE INCREASED POPS INTO THE SCT CATEGORY FOR THESE AREAS. FARTHER EAST CAP IS STRONGER...AND WILL DEPEND LARGELY ON HOW QUICKLY STRATUS BREAKS FRI MORNING...AND HOW MUCH SFC HEATING CAN BE REALIZED. FOR NOW...KEPT SOME ISOLATED POPS FOR THE EASTERN COUNTIES. AIRMASS DRIES OUT FARTHER WEST...SO THUNDERSTORM THREAT SHOULD BE MUCH LOWER. -KT .LONG TERM... (FRIDAY NIGHT THROUGH THURSDAY) IN A NUTSHELL...WEAK UPPER HIGH PRESSURE REBUILDS OVER COLORADO SATURDAY INTO SUNDAY...FOR WARMER AND DRIER CONDITIONS...BUT STILL NOT VOID OF ALL THUNDERSTORMS. LOOKS LIKE CONVECTION WILL BREAK OUT OVER THE MOUNTAINS EACH AFTERNOON...WITH ISOLATED ACTIVITY SPREADING FARTHER EAST ACROSS THE PLAINS. SUNDAY AND MONDAY...IT APPEARS THAT A SLUG OF SUBTROPICAL MOISTURE (REMNANTS OF DEAN?) WILL MAKE ITS WAY INTO COLORADO FROM THE SOUTHWEST...INCREASING PRECIP ODDS OVER THE MOUNTAINS SUNDAY AFTERNOON...AND IN ALL AREAS ON MONDAY. TUESDAY...WEAK HIGH PRESSURE REBUILDS AGAIN...FOR A WARMER AND DRIER DAY. THEN...IF THE GFS40 PROVES CORRECT...A SURFACE BOUNDARY WILL SLIP SOUTH INTO EASTERN COLORADO TUESDAY NIGHT...FOR A RETURN TO COOLER AND WETTER CONDITIONS AGAIN WEDNESDAY AND THURSDAY. ALL OF THIS IS A LONG WAY OFF AND VERY UNCERTAIN...BUT SOMETHING TO KEEP AN EYE ON. TEMPERATURES WILL LIKELY RANGE FROM NEAR TO A LITTLE ABOVE AVERAGE IN MOST AREAS FOR THE NEXT SEVERAL DAYS. LW && .AVIATION...THUNDERSTORMS WILL AFFECT THE EASTERN TAF SITES (KCOS AND KPUB) AFTER 22Z...WITH SLOWER START TO THUNDERSTORMS ANTICIPATED DUE TO SLOWER WARM UP. HOWEVER...HAIL UP TO 2 INCHES IN DIAMETER...AND WIND GUSTS OVER 50 MPH WILL BE POSSIBLE WITH THUNDERSTORMS ACROSS THE SE PLAINS. THUNDERSTORMS SHOULD EVOLVE INTO A COMPLEX ACROSS EAST CENTRAL CO AND MOVE INTO KS OVERNIGHT. WIDESPREAD IFR TO MVFR CIGS EXPECTED ACROSS THE SE PLAINS AS STRATUS BEHIND THE FRONT DEVELOPS OVERNIGHT. STRATUS SHOULD BURN OFF ON FRI BY 17-18Z...WITH ANOTHER ROUND OF THUNDERSTORMS EXPECTED ALONG THE EASTERN MOUNTAINS/ADJACENT PLAINS. LARGE HAIL UP TO 2 INCHES IN DIAMETER...AND WIND GUSTS OVER 50 MPH WILL BE POSSIBLE WITH THUNDERSTORMS AFFECTING THE KCOS AND KPUB TAF SITES FRI AFTN. && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 31/50 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 329 AM MDT THU AUG 23 2007 .SHORT TERM (TODAY THROUGH FRIDAY NIGHT)... SHORTWAVE WHICH MOVED ACROSS THE CWFA DURING THE EVENING DROVE A COOL FRONT TO THE HIGHER TERRAIN NORTH OF THE I-70 CORRIDOR ACCORDING TO LATEST RUC ANALYSES. LIFT ASSOCIATED WITH THE SHORTWAVE COMBINED WITH LOW LEVEL CONVERGENCE CONTINUED TO BRING SOME LIGHT SHOWERS TO THE NORTHERNMOST REACHES OF THE CWFA EARLY THIS MORNING. MODELS INDICATED THIS PATTERN WILL HOLD THROUGH THE MORNING HOURS. CONSEQUENTLY...CAN EXPECT UPPER LEVEL DIVERGENCE COMBINED WITH LIFT ASSOCIATED WITH WEAK MID-LEVEL DISTURBANCES FOCUSED ALONG SURFACE FRONT TO CONTINUE TO GENERATE SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ACROSS THE NORTHERN TIER COUNTIES OF COLORADO AND UTAH THROUGH MIDDAY. ANOTHER SHORTWAVE PROGGED TO ROLL ACROSS THE NORTHERN PORTION OF THE CWFA THIS AFTERNOON. DIURNAL WARMING IN COMBINATION WITH THIS DISTURBANCE WILL YIELD INCREASED ACTIVITY... STILL MAINLY NORTH OF THE I-70 CORRIDOR. SURFACE MOISTURE LIMITING FACTOR FOR MORE ENERGETIC STORMS...THOUGH DESPITE THIS SHORTCOMING ELEVATED CAPE VALUES NEARING 1000 JOULES/KG WITH DECENT STRAIGHT LINE SHEAR. AS A RESULT...COULD SEE ONE OR TWO LONG-LIVED STRONG STORMS. TROF DEEPENS IN THE EVENING SPREADING CONVECTION INTO THE SOUTHERN PORTION OF THE CWFA...DECREASING OVERNIGHT. TROF AXIS MOVES EAST OF THE DIVIDE FRIDAY MORNING FURTHER DIMINISHING CONVECTIVE ACTIVITY. RESIDUAL MOISTURE MAY BE SUFFICIENT FOR ISOLATED AFTERNOON TSTMS ALONG THE DIVIDE FRIDAY AFTERNOON...OTHERWISE EXPECT DRY CONDITIONS TO RETURN. TEMPERATURES LARGELY PERSISTENT ACROSS THE SOUTH TODAY WHILE READINGS COOLING ON THE ORDER OF 5 TO 10 DEGREES F ACROSS THE NORTH. NEAR PERSISTENCE ON FRIDAY...THOUGH SLIGHTLY WARMER NORTH. OVERNIGHT LOWS WILL RUN COOLER TONIGHT...MODERATING SLIGHTLY ON FRIDAY NIGHT. .LONG TERM...SATURDAY THROUGH WEDNESDAY... W-NW FLOW WILL BRING DRIER AIR TO THE FORECAST AREA ON SAT. TEMPS TO REBOUND FROM FRI. FORECAST CHALLENGE CONTINUES TO BE WHEN...AND HOW MUCH...MOISTURE MOVES UP FROM THE SOUTH LATER THIS WEEKEND. GFS/ECMWF CONTINUE TO BRING REMNANTS OF HURRICANE DEAN UP AROUND THE WEST END OF A BROAD E-W RIDGE...AND ACROSS ERN UT/WRN CO SUN NIGHT AND MON. HARD TO IGNORE THE RUN-TO-RUN CONSISTENCY OF THIS GENERAL SCENARIO...THOUGH APPEARS MODEL TREND MAY BE TO TAKE REMNANTS FARTHER WEST BEFORE SWINGING THEM BACK NE ACROSS THE GREAT BASIN...AND EXTRAPOLATING CURRENT TRACK OF DEAN ON IR/WVAPOR SATELLITE LOOPS MIGHT SUGGEST THAT THE BULK OF MOISTURE CONTINUES OUT INTO PAC. STILL...SOME NORTHWARD SURGE OF SUB-TROPICAL MOISTURE SEEMS REASONABLE AS WESTERLY FLOW WEAKENS OVER THE INTER-MOUNTAIN REGION THIS WEEKEND. MADE LITTLE CHANGE TO CURRENT FORECAST GRIDS AS A RESULT...KEEPING LOW-END CHANCE POPS FOR MUCH OF THE AREA SUN NIGHT-MON. MON TEMPS ESPECIALLY LOOK COOLER DUE TO CLOUD COVER AND SHOWERS. UPPER LEVEL HIGH VACILLATES OVER THE SWRN U.S. TUE-WED WITH SOME MOISTURE PERSISTING IN W-SW FLOW. BEST POTENTIAL FOR CONVECTION TOWARD MIDWEEK WILL BE REALIZED WITH SMALL SCALE DISTURBANCES...WHICH AT THIS TIME REMAIN UNRESOLVED. SO WILL BROAD BRUSH FOR SCATTERED MTN POPS AND A LITTLE MORE INSOLATION ALLOWING TEMPS TO WARM BACK TO SEASONAL NORMALS OR ABOVE. && .AVIATION... SCATTERED SHOWERS WITH ISOLATED THUNDERSTORMS THIS MORNING NORTH OF THE I-70 CORRIDOR THROUGH MIDDAY. THUNDERSTORMS MORE WIDESPREAD IN THE AFTERNOON...REMAINING MAINLY NORTH OF THE I-70 CORRIDOR. STORMS WILL BE CAPABLE OF PRODUCING STRONG OUTFLOW WINDS WITH SMALL HAIL. A FEW STORMS MAY GENERATE LARGE HAIL. SOUTH OF THE I-70 CORRIDOR EXPECT MAINLY VFR CONDITIONS WITH A FEW THUNDERSTORMS POSSIBLE. IN THE EVENING...SCATTERED STORMS WILL CONTINUE ALL ALONG THE CONTINENTAL DIVIDE BECOME MORE WIDELY SCATTERED TOWARD THE COLORADO/UTAH BORDER. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...NONE. .UT...NONE. $$ SHORT TERM...NL LONG TERM...JAD AVIATION...NL co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 710 PM EDT FRI AUG 24 2007 .UPDATE... 23Z WATER VAPOR AND H4 RUC ANALYSIS CONTINUE TO SHOW THE UPPER LEVEL RIDGE BREAK DOWN OVER THE SOUTHEAST AS SHORTWAVE ENERGY PUSHES INTO THE MIDDLE MISSISSIPPI VALLEY THIS EVENING AND THEN INTO THE WESTERN TENNESSEE VALLEY OVERNIGHT. SUBTROPICAL SURFACE RIDGE AXIS REMAINS FROM THE WESTERN ATLANTIC INTO THE SOUTHEASTERN STATES KEEPING LOW LEVEL FLOW RATHER LIGHT. SHOWERS AND THUNDERSTORMS ERUPTED EARLY THIS AFTERNOON ACROSS NORTHERN AND WESTERN PORTIONS OF THE FORECAST AREA AND THEN REDEVELOPED EASTWARD INTO SOUTHWEST GEORGIA AND THE WESTERN FLORIDA BIG BEND DURING THE LATE AFTERNOON. SOME THE STORMS WERE ON THE STRONG TO SEVERE SIDE WITH SOME VERY GUSTY WINDS AND LARGE HAIL REPORTS. MUCH OF THE AREA HAS BEEN STABILIZED BY THE EARLIER CONVECTION AND HAVE SEEN COVERAGE AND INTENSITY OF THE CONVECTION REALLY DROP OFF IN THE PAST ONE TO TWO HOURS. AREAS OF CONCERN THROUGH THE REMAINDER OF THE EVENING WILL BE SOUTH-CENTRAL GA AND THE EASTERN BIG BEND OF FLORIDA. THESE AREAS HAVE REMAINED FAIRLY CONVECTION FREE FOR MUCH OF THE DAY AND HENCE HAVE NOT STABILIZED AS MUCH AS OTHER AREAS. ALSO WILL SEE COLLISION OF AN OUTFLOW BOUNDARY FROM THE EARLIER CONVECTION TO THE WEST AND THE EAST COAST SEA-BREEZE ACROSS THIS AREA DURING THE MIDDLE EVENING HOURS. LIKELY WILL SEE AT LEAST A FEW STORMS GO UP AS A RESULT OF THIS COLLISION...BUT THE GENERAL TREND FROM THIS POINT ON SHOULD BE FOR A CONTINUED DECREASE IN CONVECTION. ALSO WATCHING A LINE OF STRONG STORMS UP TOWARD THE ATLANTA AREA SLOWLY PUSHING SOUTH AND SOUTHWEST. THIS AREA HAS QUITE A LONG WAY TO GO BEFORE REACHING OUR ZONES AND THE GOING FORECAST WILL ALLOW FOR THESE STORMS TO DISSIPATE BEFORE REACHING OUR NORTHERN GA ZONES. CONDITIONS APPEAR FAVORABLE FOR ANOTHER ACTIVE DAY OF SEA-BREEZE CONVECTION FROM EARLY SATURDAY AFTERNOON INTO THE EVENING HOURS. && .AVIATION... AFTERNOON THUNDERSTORMS PRETTY MUCH OVER FOR MOST TERMINALS ACROSS THE AREA. EXCEPTION MAY BE VLD AND ABY WHERE BOUNDARY COLLISION DURING NEXT FEW HOURS LIKELY TO TRIGGER SOME NEARBY TSRA. WILL KEEP AT LEAST VCTS IN FOR THESE SITES FOR A FEW HOURS THIS EVENING. OTHERWISE...VFR CONDITIONS SHOULD DOMINATE MOST OF THE NIGHT. WILL LIKELY SEE SOME MINOR RESTRICTIONS TO VSBY BY MORNING ESPECIALLY AT LOCATIONS THAT RECEIVED RAINFALL THIS AFTERNOON. BY AFTERNOON TOMORROW...MOIST AND UNSTABLE ATMOSPHERE LIKELY TO ERUPT ONCE AGAIN WITH PLENTY OF SHOWERS AND THUNDERSTORMS AROUND. && .MARINE... WINDS AND SEAS REMAIN RATHER LIGHT OUT OF THE SOUTHEAST AWAY FROM LINGERING ONSHORE SEA-BREEZES. WILL STILL RUN THE RISK OF A FEW SHOWERS/STORMS MIGRATING OFFSHORE FROM THE BIG BEND INTO APALACHEE BAY THIS EVENING. WINDS ASSOCIATED WITH ANY OF THESE STORMS MAY BRIEFLY GUSTS UP ABOVE 20 KNOTS...AND OF COURSE LIGHTNING WILL CONTINUE TO BE A THREAT. AFTER MIDNIGHT WOULD EXPECT MORE SCATTERED SHOWERS/STORMS TO DEVELOP ACROSS THE REMAINDER OF THE FORECAST WATERS AS LIGHT OFFSHORE FLOW DEVELOPS. LITTLE CHANGE TO THE FORECAST FOR SATURDAY. SCATTERED MORNING CONVECTION WILL SLOWLY DIMINISH. GENERALLY LIGHT SOUTHEAST TO SOUTH FLOW THROUGH THE DAY. LIKELY TO SEE ADDITIONAL LAND BASED SHOWERS/STORMS BEGIN TO MIGRATE INTO THE NEARSHORE WATERS DURING THE AFTERNOON AND EARLY EVENING HOURS. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 73 92 73 91 74 / 20 60 30 50 40 PANAMA CITY 78 91 77 91 78 / 20 50 30 50 40 DOTHAN 74 93 74 93 75 / 20 50 30 40 40 ALBANY 75 94 74 93 74 / 20 60 30 40 40 VALDOSTA 73 92 73 92 73 / 30 60 30 50 40 CROSS CITY 73 91 73 92 74 / 30 60 30 60 30 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && && $$ MROCZKA/CAMP fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 705 PM EDT THU AUG 23 2007 .UPDATE... 23Z WATER VAPOR AND H4 RUC ANALYSIS SHOWS THE FORECAST AREA ON THE SOUTHEAST EDGE OF MID/UPPER LEVEL RIDGING WITH AN AXIS RUNNING FROM NORTHWEST TEXAS TO THE CENTRAL APPALACHIANS. SURFACE RIDGE IS FIRMLY IN CONTROL NOSING INTO THE SOUTHEASTERN STATES FROM THE WESTERN ATLANTIC. DOES APPEAR TO BE A WEAK AND ILL-DEFINED SURFACE TROUGH/BOUNDARY FROM THE BIG BEND UP INTO SOUTH-CENTRAL GEORGIA AND ARE SEEING SOME SHOWERS AND THUNDERSTORMS FIRING ALONG THIS BOUNDARY AT THIS TIME. THESE SHOWERS/STORMS CONTINUE INTO SOUTHEAST GA AND ARE GENERALLY FIRING ACROSS THE REGION NOT EFFECTED AND SOMEWHAT STABILIZED BY LAST NIGHT AND THIS MORNING`S MCS THAT EFFECTED OUR NORTHERN AND WESTERN ZONES. A FEW OF THE STORMS ACROSS SOUTHEAST GEORGIA ARE BECOMING RATHER STRONG AND MAY HAVE SOME CONVECTIVE ISSUES ACROSS OUR EASTERN GA/BIG BEND ZONES THIS EVENING. WILL CONTINUE TO WATCH THINGS VERY CLOSELY AS INSTABILITY REMAINS QUITE HIGH AND THE UPPER RIDGE RETREATING SLOWLY WEST IS MINIMIZING THE CONVECTIVE SUPPRESSION. AWAY FROM ANY STORMS THIS EVENING WE ARE LOOKING AT GENERALLY PARTLY CLOUDY SKIES NOW THAT THE LINGERING HIGH LEVEL DEBRIS FROM THE OVERNIGHT MCS HAS FINALLY DISSIPATED ACROSS THE WEST. THIS CLOUD KEPT TEMPERATURES CONSIDERABLY BELOW EXPECTATIONS FOR MUCH OF THE DAY...HOWEVER READINGS HAVE BEEN ABLE TO REBOUND THE PAST FEW HOURS INTO THE UPPER 80S. && .AVIATION... WDLY SCT THUNDERSTORMS WILL CONTINUE TO DEVELOP AND INCREASE... ESPECIALLY ACROSS THE FLORIDA BIG BEND AND SOUTH CENTRAL GEORGIA... AND CONTINUE INTO THE LATE NIGHT AND EARLY MORNING HOURS. PERIODS OF MVFR CIGS AND VSBYS ARE INCLUDED IN THE TAFS BOTH FOR THE THUNDERSTORMS...AND ALSO FOR AREAS OF MIST OF FOG THAT WILL DEVELOP BEFORE SUNRISE AGAIN ON FRIDAY...ESPECIALLY IN AREAS THAT RECEIVE RAINFALL FROM THE THUNDERSTORMS. VFR CONDITIONS WILL RETURN TO ALL AREAS AFTER SUNRISE. && .MARINE... WINDS ACROSS THE COASTAL WATERS RUNNING FROM THE EAST OR SOUTHEAST AROUND 10 KNOTS THIS EVENING AWAY FROM THE ONSHORE FLOW CLOSE TO THE COAST ASSOCIATED WITH THE AFTERNOON SEA-BREEZE. SEAS RUNNING GENERALLY BETWEEN 2 AND 3 FEET. SHOULD SEE WINDS SWING AROUND TO THE EAST AND NORTHEAST ALL AREA TOWARD MIDNIGHT. A FEW ISOLATED SHOWERS/STORMS SEEN OFF THE PANHANDLE COASTLINE WILL BECOME MORE SCATTERED ACROSS THE WATERS FROM THE LATE EVENING INTO THE EARLY MORNING HOURS. && $$ MROCZKA/DUVAL fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 837 PM EDT FRI AUG 24 2007 .SYNOPSIS... HIGH PRESSURE WILL REMAIN THE DOMINANT WEATHER FEATURE THROUGH THE PERIOD. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... WILL NEED TO HOLD ONTO A SLGT CHC OF SHWRS/TSTMS ALONG COASTAL ZONES AFTER MIDNIGHT WITH LOW LEVEL STEERING FLOW REMAINING OFF THE ATLANTIC. WILL REMOVE MENTION OF POP FARTHER INLAND ALTHOUGH WILL BE WATCHING CURRENT CONVECTION ALONG THE SAVANNAH RIVER NEAR AUGUSTA TO SEE HOW FAR SOUTH IT MOVES. RUC SHOWS THE CONVECTION HOLDING OVER INTERIOR GA WITH LITTLE IN THE WAY OF MOVEMENT TOWARD THE COAST. OVERNIGHT LOWS ARE EXPECTED TO BOTTOM OUT IN THE MID 70S ACROSS MOST LOCALES WITH LIGHT AND VARIABLE WINDS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... ATLANTIC HIGH PRESSURE WILL CONTINUE TO HOLD STRONG OVER THE FORECAST AREA. WITH ONSHORE FLOW EXPECT SEA BREEZE TO DEVELOP EARLY AND PUSH INLAND QUICKLY MUCH LIKE TODAY. WILL KEEP SLGT CHC POPS GOING DURING THE MORNING FOR COASTAL AND FIRST TIER OF INTERIOR ZONES...AND KEEP EXTREME WESTERN PORTIONS OF THE CWA RAIN FREE. IN THE AFTERNOON WILL CARRY CHC POPS MOST ZONES AWAY FROM THE IMMEDIATE COAST/BEACHES WHERE SLGT CHC POPS WILL BE MAINTAINED. STRONG ONSHORE FLOW AND FAST SEA BREEZE PUSH THROUGH THE CWA SHOULD ALLOW FOR A DRY FORECAST SATURDAY NIGHT ACROSS MOST AREAS. THE ONE EXCEPTION WILL BE FOR COASTAL ZONES AFTER MIDNIGHT...WHERE AN ISOLATED SHWR/TSTM CAN/T BE RULED OUT WITH STEERING FLOW REMAINING OFF THE ATLANTIC. AS FOR TEMPERATURES...EXPECT HIGHS SIMILAR TO TODAY...MAXING OUT IN THE LOWER 90S. A HEAT ADVISORY APPEARS UNLIKELY AT THIS TIME AS HEAT INDICES SHOULD REMAIN BELOW 105 DEGREES. OVERNIGHT LOWS SAT NIGHT SHOULD BOTTOM OUT IN THE MIDDLE 70S. && .LONG TERM /SUNDAY THROUGH FRIDAY/... THE UPPER LEVEL RIDGE LOOKS TO WEAKEN SLIGHTLY...WHILE MODELS INDICATE A WEAK FRONT AT THE SURFACE WASHING OUT SUNDAY INTO MONDAY. SFC AND UPPER LEVEL RIDGING REINTENSIFIES JUST WEST OF THE AREA EARLY NEXT WEEK. SHOWERS AND THUNDERSTORMS ARE POSSIBLE THROUGH THE EXTENDED PERIOD DUE TO WEAK SHORTWAVES AND THE INTERACTION WITH THE SEA BREEZE. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... SHOULD BE VFR THROUGH THE NIGHT WITH ONLY A TEMPO MENTIONED FOR SOME MVFR VISIBILITIES BY THE PREDAWN HOURS. SHOULD SEE A REPEAT OF SCATTERED STORMS ON SATURDAY WITH CB MENTIONED IN THE AFTERNOON HOURS. EXTENDED AVIATION OUTLOOK...VFR CONDITIONS WILL PREVAIL THROUGH MUCH OF THE EXTENDED PERIOD...OUTSIDE OF SCATTERED AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS. && .MARINE... ATLANTIC HIGH PRESSURE WILL HOLD STRONG OVER THE WATERS TONIGHT THROUGH SATURDAY NIGHT...WITH WINDS REMAINING AT OR BELOW 15 KT THROUGH THE PERIOD. EASTERLY SWELL WILL SLOWLY SUBSIDE THROUGH THE PERIOD. WILL DROP THE SCEC FOR THE OUTER GA WATERS AND MAINTAIN 4 FT FOR THAT ZONE. OTHERWISE WINDS/SEAS WILL REMAIN BELOW HEADLINE THRESHOLDS THROUGH SATURDAY NIGHT. MARINE ZONES SHOULD REMAIN FAIRLY QUIET THROUGH THE EXTENDED WITH MAINLY SOUTHERLY WINDS A0B 15 KNOTS. SEAS WILL REMAIN 2 TO 4 FEET. WINDS AND SEAS MAY SLIGHTLY INCREASE IN/NEAR SHOWERS AND THUNDERSTORMS. MODELS INDICATE SLIGHT NOCTURNAL SURGING OVER THE COASTAL WATERS ESPECIALLY EARLY IN THE WEEK. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ PY ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 344 AM EDT THU AUG 23 2007 .SYNOPSIS... HIGH PRESSURE WILL REMAIN IN PLACE THROUGH THE WEEKEND. A COLD FRONT WILL APPROACH THE AREA EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CLUSTER OF STRONG THUNDERSTORMS CONTINUES TO TREK SOUTHWARD ACROSS OUR NRN SC ZONES THIS MORNING. MORE ISOLATED STORMS CONTINUE DEVELOPING ACROSS INTERIOR GEORGIA. BOTH OF THESE AREAS OF SHOWERS AND STORMS ARE DUE TO A WEAKNESS IN THE UPPER RIDGE CURRENTLY RESIDING ABOVE A THETA-E RIDGE WITH MOIST ONSHORE CONVERGENT FLOW. BOTH THE RUC AND THE NAM-12 EARLIER SHOWED AN AREA OF CONVECTION PUSHING ACROSS THE AREA OVERNIGHT AND THIS SEEMS TO BE MATERIALIZING. MORE STORMS REMAIN N OF THE AREA ACROSS NE SC...SLOWLY PUSHING S. 00Z KCHS SOUNDING SHOWED -6.5C 500 MB TEMP AND A 700-500 MB LAPSE RATE OF 6.1 C/KM. MORE CONVECTION WILL LIKELY FIRE ALONG EXTENSIVE BOUNDARIES...BE THEY ACTIVE OR REMNANT. WILL CARRY CHANCE POPS MOST AREAS THROUGH 12Z. A LULL IS EXPECTED DURING THE MID TO LATE MORNING BUT ANOTHER ROUND OF SCATTERED CONVECTION IS EXPECTED THIS AFTERNOON. WEAK UPPER LOW WILL CONTINUE TO MEANDER OVER THE AREA...WHILE LOW- LEVELS STAY MOIST WITH ONSHORE FLOW...ROBUST SEABREEZE DEVELOPS IN EARLY AFTERNOON...AND MOISTURE CONVERGENCE INCREASES AROUND 850 MB. EXPECT TODAY/S CONVECTIVE PATTERN TO BE SIMILAR TO WED WITH SCATTERED CELLS DEVELOPING BY EARLY AFTERNOON...EXPANDING IN COVERAGE AS OUTFLOW BOUNDARIES AND THE SEABREEZE COME INTO PLAY. WILL CARRY SOLID CHANCE POPS TODAY MOST AREAS AWAY FROM THE IMMEDIATE COAST. HEAT INDICES SHOULD NOT BE A PROBLEM TODAY DESPITE THE DEWPTS REMAINING IN THE 70S. LOWER THICKNESSES SHOULD YIELD HIGHS SEVERAL DEGREES BELOW YESTERDAY/S READINGS...KEEPING HEAT INDICES IN THE 100 TO 105 RANGE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... FRIDAY...THE UPPER RIDGE AXIS LOOKS TO SHIFT A TAD E WHILE THE ATLC SURFACE RIDGE BUILDS W. ANOTHER ACTIVE SEABREEZE IS EXPECTED WITH 1000-1500 J/KG CAPE DEVELOPING ACROSS THE EASTERN TWO-THIRDS BY AFTERNOON. ALTHOUGH UPPER LEVELS WILL BE WARMER WITH STRONGER CAPPING...STILL EXPECT ISOLATED TO SCATTERED SHOWERS AND STORMS TO DEVELOP. TEMPS TO BE COMPARABLE TO THU WITH HEAT INDICES AGAIN JUST BELOW ADVISORY CRITERIA. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... INVERTED UPPER TROUGH WITH AMPLE LOW-LEVEL MOISTURE SHOULD YIELD SLIGHTLY ABOVE-NORMAL POPS THROUGH THE WEEKEND. HEAT INDICES WILL BE FLIRTING WITH ADVISORY CRITERIA SEVERAL DAYS...MAINLY FAR INLAND ZONES WHERE HIGHEST TEMPS ARE EXPECTED. COOL FRONT TO APPROACH FROM THE N LATE IN THE PERIOD...HOWEVER STRONG RIDGING IN PLACE WILL LIKELY PREVENT IT FROM MAKING IT AS FAR S AS OUR AREA BEFORE WASHING OUT. CLIMO POPS/TEMPS MON THROUGH WED. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... MUCH OF THE 00Z MODEL GUIDANCE SUGGESTING TODAY WILL BE AN ACTIVE CONVECTIVE DAY AROUND BOTH OF OUR MAJOR AIRPORTS. MAIN PROBLEM AT THE CURRENT TIME IS THE SELECTION OF A MOST LIKELY TIME FRAME WINDOW. STRONG STORMS CONTINUE TO FLIRT WITH THE CHS TERM ALTHOUGH THE STRONGEST CORES HAVE GONE TO THE W. CONTINUED BUILDING ALONG AN EXTENSIVE OUTFLOW MAY WELL BRING TSRA THROUGH CHS TERM IN THE NEXT TWO HOURS. TEMPO/D TSRA THROUGH 09Z. KSAV MAY SEE STORMS DEVELOPING AROUND 12Z...BUT WE WILL HAVE TO WAIT AND SEE HOW THE UPSTREAM AND DOWNSTREAM CONVECTION INTERACTS. EXTENDED AVIATION OUTLOOK...VFR CONDITIONS WILL PREVAIL THROUGH MUCH OF THE EXTENDED PERIOD...OUTSIDE OF AN ISOLD AFTN/EVNG SHOWER OR TSTM. && .MARINE... TSTMS JUST INLAND APPEAR TO BE A SIGNIFICANT IMPETUS FOR YANKING THE BACKDOOR BOUNDARY SOUTHWARD THROUGH THE WATERS THIS MORNING. BOTH THE NAM AND GFS IN BETTER AGREEMENT ON COASTAL WINDS THIS MORNING WITH LIGHT S AND SW FLOW CURRENTLY...SHIFTING ONSHORE QUICKLY TODAY. WE TEND TO LIKE THE SLIGHTLY BETTER SURGES DISPLAYED BY THE NAM. SEAS AND SWELL COMPONENT GRADUALLY BUILDING TODAY INTO TONIGHT BUT THE SEAS LIKELY TO STAY BLO SCA CRITERIA UNLESS MORE SURGING THAN FORECAST OCCURS. MOST OF THE TRENDS FOR BOTH WINDS AND SEAS WERE MAINTAINED THIS FORECAST. RIP CURRENTS...WITH INCREASING AFTN ONSHORE FLOW AND SWELLS ALSO ON THE INCREASE WITH AN ADDED GROUND SWELL...WE HAVE INDICATED A MODERATE RISK OF RIP CURRENTS TODAY...ESPECIALLY LATE AFTN OR EARLY EVENING HOURS WITH THE TIDE HEADED OUT. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ JRL/24 ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 345 PM CDT FRI AUG 24 2007 .DISCUSSION... FLOODED AREA IN NRN IL APPEAR TO GET A REPRIEVE FROM HEAVY RAINFALL. OUTFLOW FROM STORMS YDA HAVE SWEPT BOUNDARY SWD THRU AREA. THIS BOUNDARY STRETCHING FROM SBN TO BMI WHERE TSTMS HAVE BEGUN FIRING. CONTD CLOUDY CONDS NORTH OF THERE HAVE SUBDUED DAYTIME HEATING BLO CONVECTIVE TEMP AROUND 80. TEMPS SOUTH OF CLOUD COVER AND BOUNDARY REACHING MID 90S. SO FAR SO GOOD. FIRST UPR WAVE MOVING NE FROM STL LIKELY TO FOLLOW PATH OF CURRENT CONVECTION IN IROQUOIS AND BENTON COUNTIES IN FAR SRN CWA. SVR TSTM WATCH JUST GOING OUT FOR FORD TO JASPER COUNTIES IN SERN PART OF CWA. MAY SEE SOME DEVELOPMENT AFTER 6PM REST OF CWA TO THE NORTH...BUT THINK THAT SVR THREAT WILL REMAIN SOUTH. FLOODING IS NEXT ISSUE. COUNTIES IN WATCH CAN HANDLE MORE PCPN THAN NORTH SO THINGS ARE WORKING OUT WELL SO FAR. HOWEVER NOT TAKING MUCH TO RETURN FLOODING OR SUBDUE WATER RETREAT IN ALREADY SATURATED NORTH SECTIONS. LATEST UPDATES FOR EXCESS RAINFALL HAS REMOVED HIGH RISK OF HEAVY RAIN FROM THE MAP AND REDUCED TO MODERATE WHILE SHIFTING AXIS FROM CHICAGO TO LASALLE TO GARY TO LACON. WAUKEGAN TO ROCKFORD ON NORTH NOW OUT OF EVEN SLIGHT RISK OF HEAVY RAIN. MODERATE RISK OF SEVERE NOW DROPPED SOUTH AS WELL...CLEARING THE MAJORITY OF NE IL WITH NRN EXTENT OF MODERATE THREAT FROM SBN TO BMI. AREAS NORTH OF CHI TO LASALLE LINE EVEN OUT OF SLIGHT RISK FOR SEVERE. COLD FNT IN WISCONSIN WAITING TO DROP DOWN INTO IL OVERNIGHT. THIS AWAITING MAIN UPR TROF MOVG INTO MS VLY ERY SAT MRNG. SECOND WAVE OF STORMS MOVING INTO NRN IL AHEAD OF UPR TROF NEAR MDNGT BUT SHUD BE SUBDUED ENUF TO LOSE ANY SEVERE POTENTIAL...BUT MAY DROP A QTR TO HALF INCH OF RAIN EVEN IN NRN SECTIONS OVERNIGHT. SHUD SEE END OF STRONG CONVECTION WITH FROPA BUT STILL LEAVING RISK OF SHOWERS SAT UNTIL UPR TROF CROSSES THRU FCST AREA SAT EVENING. SFC HI PRESSURE BLDG IN SAT NGT AND DROPPING WINDS TO L/V WHILE CLEARING SKIES. WITH GROUND MSTR ABUNDANT AND CLR SKIES...SHUD LIKELY SEE FOG DEVELOP. POST FRONTAL DEWPTS ONLY LOWERING INTO UPR 50S TO LOW 60S...SO HUMIDITY HOVERING NEAR THE UNCOMFORTABLE RANGE. NEXT THREAT OF RAIN LATE TUE NGT OR WED...SO HAVE A FEW DAYS TO DRY OUT BEFORE NEXT ONSLAUGHT. RLB && .AVIATION... 100 PM CDT MAIN AVIATION FOCUS WILL BE ON CEILINGS EARLY THIS AFTERNOON...AND THEN CONVECTIVE CHANCES LATER THIS AFTERNOON INTO THIS EVENING. COMBINATION OF GOOD DEAL OF CLOUD COVER AND MOIST LOW LEVELS HAVE ALLOWED MVFR CIGS TO BE MAINTAINED ACROSS MANY LOCATIONS. EXPECTING THESE MVFR CIGS TO PERSIST THROUGH THE 20-21Z TIME FRAME...BUT WITH DIURNAL WARNING SHOULD TEND TO SEE THESE CIGS LIFT TO HIGHER END MVFR IN THE 2-3 FT RANGE. A COUPLE OF SHORT WAVES/MCV`S WILL NEED TO BE WATCHED THIS AFTERNOON FOR CONVECTIVE REDEVELOPMENT. THE FIRST OF THESE SHORT WAVES IS ENTERING FAR SOUTHEAST IOWA AT THIS TIME WITH ANOTHER SHORT WAVE ACROSS CENTRAL MISSOURI. THUNDER HAS BEEN INCREASING ACROSS CENTRAL MISSOURI AS THIS SHORT WAVE ENTERS A MODERATELY UNSTABLE AIR MASS. SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATE AN AXIS OF MLCAPES FROM 1000-1500 J/KG EXTENDING FROM EASTERN MISSOURI INTO CENTRAL INDIANA. ALTHOUGH PRIMARY INSTABILITY AXIS IS EXPECTED TO REMAIN JUST SOUTH OF THE TERMINALS THIS AFTERNOON...FAVORABLE SHEAR PROFILES AND MID/UPPER FORCING SHOULD BE CONDUCIVE FOR THUNDERSTORM DEVELOPMENT THIS AFTERNOON/EVENING. WITH MAIN MID LEVEL TROUGH AXIS SLOW TO CLEAR THE AREA THROUGH EARLY SATURDAY MORNING WILL HOLD ONTO SHOWER MENTION THROUGH MUCH OF THE OVERNIGHT HOURS. ALSO MAINTAINED SOME IFR CIGS LATE TONIGHT/EARLY SATURDAY MORNING BEFORE SLIGHTLY DRIER AIR IS ADVECTED SOUTHWARD. ON SATURDAY...CIGS SHOULD LIFT TO MVFR IN THE MORNING WITH NORTH WINDS INCREASING TO AROUND 10 KNOTS. MARSILI && .MARINE... 250 PM CDT A SURFACE TROUGH WILL CONTINUE TO SAG SOUTHEAST THROUGH THE GREAT LAKES REGION TONIGHT ALLOWING FOR SOUTHWEST WINDS ON THE SOUTHERN HALF OF THE LAKE TO SHIFT WESTERLY THIS EVENING AND NORTHWEST OVERNIGHT. AS THE MAIN SFC LOW PULLS OFF TO THE EAST EARLY SATURDAY MORNING...NORTH WINDS WILL INCREASE INTO THE 10 TO 20 KNOT RANGE WITH GUSTS UP TO AROUND 25 KNOTS. WINDS AND WAVES WILL DIMINISH SATURDAY NIGHT AS A SFC ANTICYCLONE SETTLES INTO THE REGION. WINDS WILL SHIFT TO THE SOUTH BY SUNDAY AND INCREASE TO 15 TO 20 KNOTS AHEAD OF THE NEXT TROUGH OF LOW PRESSURE TO APPROACH THE REGION. FOR THE NEARSHORE WATERS...MAY GET CLOSE TO SMALL CRAFT ADVISORY CONDITIONS ON SATURDAY GIVEN NORTHERLY WINDS GUSTING TO 20 KNOTS. WAVES WILL SUBSIDE SATURDAY NIGHT AS LOW LEVEL WINDS VEER TO THE EAST. && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLASH FLOOD WATCHES IN EFFECT THROUGH EARLY SATURDAY MORNING. IN...FLASH FLOOD WATCHES IN EFFECT THROUGH EARLY SATURDAY MORNING. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 100 PM CDT FRI AUG 24 2007 .DISCUSSION... MAIN FORECAST CONCERN CONTINUES TO BE FLOODING FROM WAVE AFTER WAVE AFTER WAVE OF SHOWERS AND THUNDERSTORMS. HAVE SEEN A GENERAL WEAKENING TREND IN CONVECTION OVER NORTHERN IL AND NORTHWEST IN AND A DECREASE IN LIGHTNING ACTIVITY OVER THE LAST FEW HOURS. HOWEVER CONVECTION CONTINUES NONETHELESS. PROFILER DATA SHOWS 40 TO 50 KNOT 850 JET FROM TX AND OK ACROSS ERN KS INTO MO AND IL. GFS HAS THE 850 JET WEAKENING AND TURNING MORE WLY INTO CENTRAL IL AND IN THIS MORNING. WOULD EXPECT CONVECTION TO CONTINUE TO WEAKEN OVER NRN IL THIS MORNING. FAIRLY VIGOROUS LOOKING SHORT WAVE SEEN IN WV IMAGERY OVER WRN NE AND KS. THIS IS APPARENTLY FIRING LINEAR MCS FROM NE KS AND NW MO INTO SRN IA. THIS ACTIVITY SHOULD MOVE ENE INTO CENTRAL IL AND THE SOUTHERN PART OF CWA TODAY. MODELS BRING SHORT WAVE THROUGH IL BY EVENING. LOTS OF QUESTIONS ABOUT WHEN AND WHERE HEAVIEST RAIN WILL FALL BUT WITH SEVERAL WAVES OF THUNDERSTORMS PUSHING OUTFLOW DOWN INTO CENTRAL IL AND CURRENT TRENDS OF RADAR...WOULD EXPECT THE FOCUS FOR HEAVIEST RAIN AND BEST SEVERE THREAT TO BE ACROSS SOUTHERN PART OF CWA GENERALLY SOUTH OF A PIA TO CHICAGO LINE. AXIS OF HIGHER THETA E ACROSS CENTRAL IL AS WELL. HOWEVER WITH PRECIPITABLE WATER STILL AROUND 2 INCHES OVER ENTIRE FORECAST AREA...AND ALREADY SOGGY GROUND...WILL CONTINUE FLASH FLOOD WATCH FOR ENTIRE AREA THROUGH TONIGHT. TEMPERATURES COULD GO ANYWHERE. CLOUDS AND REMNANTS OF CONVECTIVE CARCASS WILL LIMIT SUNSHINE AND HEATING...BUT SOME BREAKS COULD ALLOW TEMPS TO REBOUND INTO MID OR UPPER 80S ESPECIALLY SOUTHERN PART OF CWA. BUT EXPECT MOSTLY UPPER 70S TO LOW 80S ACROSS THE AREA. FRONT FINALLY PUSHES THROUGH LATE TONIGHT BRINGING DRIER AIR TO THE REGION. DEWPOINTS IN THE UPPER 50S AS ADVERTISED BY MOS FOR THE WEEKEND WOULD BE DELIGHTFUL...BUT LOTS OF STANDING WATER EVERYWHERE MAY KEEP HUMIDITY UP THROUGH THE WEEKEND. STILL IT SHOULD BE CONSIDERABLY MORE PLEASANT THAN ITS BEEN. BRING ON THE MOSQUITOES. NO CHANGES TO LATER PERIODS. ALLSOPP && .AVIATION... 100 PM CDT MAIN AVIATION FOCUS WILL BE ON CEILINGS EARLY THIS AFTERNOON...AND THEN CONVECTIVE CHANCES LATER THIS AFTERNOON INTO THIS EVENING. COMBINATION OF GOOD DEAL OF CLOUD COVER AND MOIST LOW LEVELS HAVE ALLOWED MVFR CIGS TO BE MAINTAINED ACROSS MANY LOCATIONS. EXPECTING THESE MVFR CIGS TO PERSIST THROUGH THE 20-21Z TIME FRAME...BUT WITH DIURNAL WARNING SHOULD TEND TO SEE THESE CIGS LIFT TO HIGHER END MVFR IN THE 2-3 FT RANGE. A COUPLE OF SHORT WAVES/MCV`S WILL NEED TO BE WATCHED THIS AFTERNOON FOR CONVECTIVE REDEVELOPMENT. THE FIRST OF THESE SHORT WAVES IS ENTERING FAR SOUTHEAST IOWA AT THIS TIME WITH ANOTHER SHORT WAVE ACROSS CENTRAL MISSOURI. THUNDER HAS BEEN INCREASING ACROSS CENTRAL MISSOURI AS THIS SHORT WAVE ENTERS A MODERATELY UNSTABLE AIR MASS. SPC RUC MESOSCALE ANALYSIS GRAPHICS INDICATE AN AXIS OF MLCAPES FROM 1000-1500 J/KG EXTENDING FROM EASTERN MISSOURI INTO CENTRAL INDIANA. ALTHOUGH PRIMARY INSTABILITY AXIS IS EXPECTED TO REMAIN JUST SOUTH OF THE TERMINALS THIS AFTERNOON...FAVORABLE SHEAR PROFILES AND MID/UPPER FORCING SHOULD BE CONDUCIVE FOR THUNDERSTORM DEVELOPMENT THIS AFTERNOON/EVENING. WITH MAIN MID LEVEL TROUGH AXIS SLOW TO CLEAR THE AREA THROUGH EARLY SATURDAY MORNING WILL HOLD ONTO SHOWER MENTION THROUGH MUCH OF THE OVERNIGHT HOURS. ALSO MAINTAINED SOME IFR CIGS LATE TONIGHT/EARLY SATURDAY MORNING BEFORE SLIGHTLY DRIER AIR IS ADVECTED SOUTHWARD. ON SATURDAY...CIGS SHOULD LIFT TO MVFR IN THE MORNING WITH NORTH WINDS INCREASING TO AROUND 10 KNOTS. MARSILI && .MARINE... 1015 PM CDT A TROUGH OF LOW PRESSURE AND AN ASSOCIATED COLD FRONT EXTEND FROM EASTERN LAKE HURON...THROUGH NORTHERN LAKE MICHIGAN...THEN SOUTHWEST TO THE CENTRAL PLAINS. THE FRONT WILL MOVE DOWN LAKE MICHIGAN TODAY...REACHING THE SOUTHERN TIP THIS EVENING. A SURGE OF COOLER AIR BEHIND THE FRONT WILL DRIVE WINDS OF 10 TO 20 KNOTS... OCCASIONALLY REACHING 25KT DURING THE DAY FRIDAY. PERIODS OF STRONG THUNDERSTORMS WILL PRECEED THE FRONT...OVER SOUTHERN PORTIONS OF THE LAKE DURING THE AFTERNOON AND EVENING HOURS. HIGH PRESSURE BUILDING OVER THE NORTHERN PLAINS WILL MOVE OVER LAKE MICHIGAN SATURDAY THEN MOVE OVER THE EASTERN LAKES SUNDAY. A LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP OVER THE CANADIAN ROCKIES ON SUNDAY AND MOVE OUT OVER SOUTH CENTRAL CANADA EARLY NEXT WEEK AS A TROUGH OF LOW PRESSURE OF 29.6 INCHES DEVELOPS OVER THE NORTHERN PLAINS. KREIN && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLASH FLOOD WATCHES IN EFFECT THROUGH EARLY SATURDAY MORNING. IN...FLASH FLOOD WATCHES IN EFFECT THROUGH EARLY SATURDAY MORNING. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 750 PM EDT FRI AUG 24 2007 .AVIATION... THE LINE OF STORMS HAS MOVED EASTWARD OF FWA. JUST OFF AND ON RAIN SHOWERS IN THE IMMEDIATE FUTURE FOR FWA. LOOKING AT RADARS...THERE ARE SOME MORE RAIN SHOWERS IN EAST CENTRAL ILLINOIS MOVING NORTHEASTWARD...SO MADE THE TEMPO GROUP FOR FWA FOUR HOURS LONG. THE RAIN SHOWERS AT FWA COULD DROP CONDITIONS OFF AND ON DOWN INTO MVFR. HARD TO SAY YET AT THE MOMENT IF ANY MORE CONVECTIVE ACTIVITY FOR LATER TONIGHT. ANOTHER SHORTWAVE IS PRODUCING SOME CONVECTION IN SOUTHERN WISCONSIN BUT THE RUC DOES NOT MOVE THIS INTO SBN THROUGH THE NIGHTTIME HOURS. WITHOUT THE FRONT BEING TO THE EAST OF THE AREA...CAN NOT COMPLETELY RULE OUT ANY PRECIP FOR LATER TONIGHT...SO WILL HAVE TO MONITOR RADARS FOR ANY FURTHER DEVELOPMENT FOR ANY AMENDMENTS TO THE TAFS. WITH THE FRONT PROGGED TO MOVE ON TO THE EAST TOMORROW...THE WIND WILL BE TURNING TO THE NORTHWEST. && .PREV DISCUSSION... /ISSUED 439 PM EDT FRI AUG 24 2007/ SHORT TERM...TONIGHT AND TOMORROW. SHOWER AND THUNDERSTORM CHANCES WILL BE AROUND TIL THAT FRONT FINALLY MOVES AWAY FROM THE CWA TOMORROW. STORMS THIS AFTERNOON INTO THIS EVENING WILL HAVE THE CHANCE TO BECOME SEVERE...WITH DAMAGING WINDS THE PRIMARY CONCERN. ANY STORMS AND SHOWERS WILL ALSO BE CAPABLE OF PRODUCING HEAVY RAINFALL. PRECIPITABLE WATER IS UP IN THE TWO TO TWO AND A HALF INCH RANGE. CAPE VALUES ARE UP TO 2000 J/KG. LIFTED INDEX VALUES DOWN TO NEGATIVE SIX. TOTAL TOTAL VALUES UP TO 55. SWEAT INDEX VALUES UP TO 445. SO THE ATMOSPHERE IS DEFINITELY UNSTABLE ENOUGH FOR SEVERE WEATHER. THE WIND FIELD FROM THE SURFACE UP IS FAIRLY UNIFORM IN TERMS OF DIRECTION BUT THERE IS DEFINITELY A DIFFERENCE IN SPEED. MID LEVELS ARE PROGGED TO BE UP TO AROUND 50 KNOTS WITH JUST ABOVE THAT AROUND 60 TO 70 KNOTS. THIS WILL HELP IN THUNDERSTORM DEVELOPMENT AND TO KEEP ANY STORMS GOING. THEN ROUGHLY AFTER MIDNIGHT RAIN CHANCES DECREASE SOME...BUT LIKE MENTIONED ABOVE...UNTIL THAT FRONT MOVES ON TO THE EAST...SHOWERS AND THUNDERSTORMS WILL STILL BE POSSIBLE. THAT FRONT HAS BEEN VERY HELPFUL THIS PAST WEEK IN GIVING US SHOWERS AND STORMS. BY 12Z SATURDAY A LOW IS PROGGED TO BE JUST NORTHEAST OF DETROIT WITH THE FRONT RIGHT THROUGH OUR CWA. THEN BY 00Z SUNDAY THE FRONT WILL BE TO OUR SOUTHEAST WITH HIGH PRESSURE MOVING IN BEHIND THE DEPARTING FRONT. WITH THE EXPECTED LARGE RAINFALL AMOUNTS EXPECTING LATE THIS AFTERNOON AND THIS EVENING...ADDING TO THE FLOODING PROBLEMS ALREADY IN THE CWA...THE FLASH FLOOD WATCH WILL BE CONTINUED INTO TONIGHT. LONG TERM...TOMORROW NIGHT THROUGH FRIDAY. BREAK IN HEAT...HUMIDITY...AND RAIN TO BEGIN EXTENDED PERIOD. SFC HIGH PRESSURE OVER THE GREAT LAKES REGION SUNDAY WILL PROVIDE SUNNY DAY WITH PLEASANT TEMPS AND LOW HUMIDITIES. HIGH WILL SLIDE OFF TO EASTERN SEABOARD BEGINNING OF NEXT WEEK RESULTING IN GRADUAL WARMING TREND WITH TEMPS REACHING 85-90F RANGE BY TUE. NEXT FRONT TO ARRIVE ON WED BRINGING CHANCE OF SH/TSRA TO THE AREA. MEDIUM RANGE MODELS INDICATING BONAFIDE COOL CANADIAN AIRMASS TO COME IN BEHIND THIS SYSTEM BRINGING DRY WX AND BELOW NORMAL TEMPS TO THE REGION AS 850MB TEMPS PROGGED TO DROP BELOW 10C BY NEXT FRIDAY. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...FLASH FLOOD WATCH UNTIL 6 AM EDT /5 AM CDT/ SATURDAY FOR INZ003>009-012>018-020-022>027-032>034. MI...FLASH FLOOD WATCH UNTIL 6 AM EDT SATURDAY FOR MIZ077>081. OH...FLASH FLOOD WATCH UNTIL 6 AM EDT SATURDAY FOR OHZ001-002-004-005- 015-016-024-025. LM...NONE. && $$ SHORT TERM...LOTHAMER LONG TERM....LOGSDON AVIATION...LOTHAMER in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 705 PM EDT FRI AUG 24 2007 .AVIATION...DISCUSSION FOR 0Z TAFS. PLENTY OF AVAILABLE INSTABILITY AND APPROACH OF MID LVL WAVE OVR W IL WL CONT TO FORCE TSRA ACRS THE AREA. CHALLENGE WL BE TIMING OFF AND ON. MAIN UPR WAVE AND COLD FRONT WON/T MOVE THRU TIL LATE TOMORROW MORNING SO THESE COULD SPAWN MORE TSRA DURING THE OVERNIGHT/MORNING HOURS. WL TIME IN CURRENT TSRA AND TAKE A SHOT AT THOSE STORMS CURRENTLY IN THE ST LOUIS AREA BUT ONLY PUT IN SHRA FOR TOMORROW MORNING. MVFR CIGS/VSBYS MAY HANG AROUND NEAR/AFTER FROPA. && .SHORT TERM /TONIGHT AND SATURDAY DAYTIME/... KIND 88D IS QUIET FOR THE MOMENT. A FEW TSRA WERE POPPING UP OVER SOUTHERN ILLINOIS WITHIN THE WATCH BOX THERE. TSRA TIMING AND FROPA ON SATURDAY WILL BE THE MAIN FOCUS. LAPS DATA SHOWS LIS IN THE -4 TO -6 RANGE WHILE SBCAPES HAVE INCREASED TO 1500-3200 J/KG. A 17Z ACARS OB SHOWS THE LOW LEVEL INVERSION HAS ERODED BUT H7 TEMPS STILL REMAIN WARM AROUND 11C. SPC MESOANALYSIS PAGE SHOWS GENERALLY DECREASING CIN BUT STILL SOME LINGERING AT 18Z. A FEW STORMS IN ILLINOIS CLOSE TO THE INDIANA BORDER HAVE DISSIPATED LIKELY DUE TO THE AFOREMENTIONED CONDITIONS. THEREFORE CONVECTION WILL LIKELY BE DELAYED UNTIL LATER ON THIS EVENING. WOULD NOT EXPECT ANYTHING IN THE CWA BEFORE 21Z. AFTER THAT A LINE OF STORMS WILL PASS THROUGH WITH DAMAGING WIND AND VERY HEAVY RAIN THE MAIN THREAT. A COLD FRONT WAS OVER IOWA THIS AFTERNOON AND WILL SLOWLY PROGRESS SOUTHEAST OVERNIGHT. WILL MOSTLY LEAN TOWARD THE NAM/RUC FOR FROPA THIS FRONT WILL BE THE FOCUS FOR ADDITIONAL PRECIPITATION OVERNIGHT AND INTO SATURDAY. THE FRONT SHOULD BE CLEAR OF THE CWA BY LATE SATURDAY EVENING AND END MOST OF THE RAINFALL. OVERNIGHT LOWS TONIGHT WILL BE IN THE LOW 70S WITH RAIN EXPECTED. ON SATURDAY WITH MOSTLY CLOUDY SKIES ANTICIPATED TEMPS WILL STAY UNDER 90 FOR THE VAST MAJORITY OF THE CWA. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... WL KEEP SLGT CHC OF TRW`S IN SATURDAY EVE AS THE UPR TROF MOVES ACRS AND THE CD FNT SETTLES S OF THE OH RVR. AFTER THAT...SHOULD BE A PERIOD OF TRANQUIL WX AS SFC HIGH PRES SETTLES ACRS THE ERN CONUS WITH RIDGING ALOFT MOVING ACRS THE OH VLY AND A DRY COLUMN WITH MN LVL RH FM 30-40% THROUGH TUE. CHC OF TRW`S AGAIN BY WED IN NW FLOW REGIME. WL NOT BE NEARLY AS WARM FOLLOWING THE FROPA AS SEEN IN CURRENT POST FRONTAL SFC OBS. MOS NUMBERS REFLECT THIS WELL AND ARE PRETTY CLOSE. && .IND WATCHES/WARNINGS/ADVISORIES...SEVERE THUNDERSTORM WATCH 648 UNTIL 11 PM EDT. && $$ AVIATION...CP SHORT TERM...SALLY LONG TERM...MK in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 245 PM EDT FRI AUG 24 2007 .SHORT TERM /TONIGHT AND SATURDAY DAYTIME/... KIND 88D IS QUIET FOR THE MOMENT. A FEW TSRA WERE POPPING UP OVER SOUTHERN ILLINOIS WITHIN THE WATCH BOX THERE. TSRA TIMING AND FROPA ON SATURDAY WILL BE THE MAIN FOCUS. LAPS DATA SHOWS LIS IN THE -4 TO -6 RANGE WHILE SBCAPES HAVE INCREASED TO 1500-3200 J/KG. A 17Z ACARS OB SHOWS THE LOW LEVEL INVERSION HAS ERODED BUT H7 TEMPS STILL REMAIN WARM AROUND 11C. SPC MESOANALYSIS PAGE SHOWS GENERALLY DECREASING CIN BUT STILL SOME LINGERING AT 18Z. A FEW STORMS IN ILLINOIS CLOSE TO THE INDIANA BORDER HAVE DISSIPATED LIKELY DUE TO THE AFOREMENTIONED CONDITIONS. THEREFORE CONVECTION WILL LIKELY BE DELAYED UNTIL LATER ON THIS EVENING. WOULD NOT EXPECT ANYTHING IN THE CWA BEFORE 21Z. AFTER THAT A LINE OF STORMS WILL PASS THROUGH WITH DAMAGING WIND AND VERY HEAVY RAIN THE MAIN THREAT. A COLD FRONT WAS OVER IOWA THIS AFTERNOON AND WILL SLOWLY PROGRESS SOUTHEAST OVERNIGHT. WILL MOSTLY LEAN TOWARD THE NAM/RUC FOR FROPA THIS FRONT WILL BE THE FOCUS FOR ADDITIONAL PRECIPITATION OVERNIGHT AND INTO SATURDAY. THE FRONT SHOULD BE CLEAR OF THE CWA BY LATE SATURDAY EVENING AND END MOST OF THE RAINFALL. OVERNIGHT LOWS TONIGHT WILL BE IN THE LOW 70S WITH RAIN EXPECTED. ON SATURDAY WITH MOSTLY CLOUDY SKIES ANTICIPATED TEMPS WILL STAY UNDER 90 FOR THE VAST MAJORITY OF THE CWA. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... WL KEEP SLGT CHC OF TRW`S IN SATURDAY EVE AS THE UPR TROF MOVES ACRS AND THE CD FNT SETTLES S OF THE OH RVR. AFTER THAT...SHOULD BE A PERIOD OF TRANQUIL WX AS SFC HIGH PRES SETTLES ACRS THE ERN CONUS WITH RIDGING ALOFT MOVING ACRS THE OH VLY AND A DRY COLUMN WITH MN LVL RH FM 30-40% THROUGH TUE. CHC OF TRW`S AGAIN BY WED IN NW FLOW REGIME. WL NOT BE NEARLY AS WARM FOLLOWING THE FROPA AS SEEN IN CURRENT POST FRONTAL SFC OBS. MOS NUMBERS REFLECT THIS WELL AND ARE PRETTY CLOSE. && .AVIATION...DISCUSSION FOR 18Z TAFS AT THIS TIME IT LOOKS LIKE THE FIRST FEW HOURS OF THE TAF PD WILL BE DRY BUT TSRA WILL MOVE INTO LAF...HUF...IND AND EVENTUALLY BMG IN THAT ORDER. A FEW THINGS ARE WORKING AGAINST EARLY AFTERNOON CONVECTIVE DEVELOPMENT AND THAT IS CURRENT ACARS DATA SHOW AN INVERSION HANGING ON AROUND 900-950MB...CIRRUS OVERHEAD SEEMS TO BE THICKENING KEEPING SOMEWHAT OF A LID ON INSTABILITY AND 700MB TEMPS ARE ANYWHERE FROM 11C-12C WHICH IS WARM FOR TSRA DEVELOPMENT. THE RUC SEEMS TO BE CATCHING THE BITS OF CONVECTION OVER SOUTHERN ILLINOIS THIS AFTERNOON SO WILL USE THAT AS A GUIDE FOR TIMING CONVECTION INTO THE TAF SITES. THE RUC FORECASTS CAP EROSION NEAR LAF BY 21Z SO WOULD EXPECT TSRA TO BE IN THE AREA BY THEN. AS THE COLD FRONT GETS CLOSER AND MORE CAP EROSION OCCURS WILL INCLUDE TSRA IN HUF AND IND BY 23Z-24Z AND INTO BMG BY 01Z. AFTER 01Z TIMING WILL BE MORE DIFFICULT AND AMENDMENTS WILL BE NECESSARY TO UPDATE ANY CHANGES IN TIMING AND MOVEMENT OF ONGOING CONVECTION. COLD FRONT WILL BRING ANOTHER ROUND OF SHOWERS OVERNIGHT AND INTO THE DAYTIME. FRONT SHOULD BE THROUGH ALL TAF SITES AFTER THE END OF THIS TAF VALID PD. && && .IND WATCHES/WARNINGS/ADVISORIES...NONE && $$ SHORT TERM/AVIATION...SALLY LONG TERM...MK in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 120 PM EDT FRI AUG 24 2007 .AVIATION...DISCUSSION FOR 18Z TAFS MOSTLY VFR FORECAST IN STORE EXCEPT WHEN THUNDERSTORMS PASS THROUGH. AT THIS TIME IT LOOKS LIKE THE FIRST FEW HOURS OF THE TAF PD WILL BE DRY BUT TSRA WILL MOVE INTO LAF...HUF...IND AND EVENTUALLY BMG IN THAT ORDER. A FEW THINGS ARE WORKING AGAINST EARLY AFTERNOON CONVECTIVE DEVELOPMENT AND THAT IS CURRENT ACARS DATA SHOW AN INVERSION HANGING ON AROUND 900-950MB...CIRRUS OVERHEAD SEEMS TO BE THICKENING KEEPING SOMEWHAT OF A LID ON INSTABILITY AND 700MB TEMPS ARE ANYWHERE FROM 11C-12C WHICH IS WARM FOR TSRA DEVELOPMENT. THE RUC SEEMS TO BE CATCHING THE BITS OF CONVECTION OVER SOUTHERN ILLINOIS THIS AFTERNOON SO WILL USE THAT AS A GUIDE FOR TIMING CONVECTION INTO THE TAF SITES. THE RUC FORECASTS CAP EROSION NEAR LAF BY 21Z SO WOULD EXPECT TSRA TO BE IN THE AREA BY THEN. AS THE COLD FRONT GETS CLOSER AND MORE CAP EROSION OCCURS WILL INCLUDE TSRA IN HUF AND IND BY 23Z-24Z AND INTO BMG BY 01Z. AFTER 01Z TIMING WILL BE MORE DIFFICULT AND AMENDMENTS WILL BE NECESSARY TO UPDATE ANY CHANGES IN TIMING AND MOVEMENT OF ONGOING CONVECTION. COLD FRONT WILL BRING ANOTHER ROUND OF SHOWERS OVERNIGHT AND INTO THE DAYTIME. FRONT SHOULD BE THROUGH ALL TAF SITES AFTER THE END OF THIS TAF VALID PD. && .DISCUSSION... FORECAST FOCUS IS ON TEMPS TODAY AND POPS INTO SATURDAY. AT 06Z AN OUTFLOW BOUNDARY WAS CUTTING THE FORECAST AREA /FA/ IN HALF WITH MODIFIED AIR TO THE N. TSRA WERE DEVELOPING IN WARM ADVECTION ABOVE THE MODIFIED AIR ACROSS NWRN FA. TSRA WERE ALSO STRUNG OUT FROM KS NE INTO IL. UPPER WAVE WAS ACROSS ERN CO. MODELS STRUGGLING WITH PRECIP PLACEMENT LATELY AND EACH SUFFER FROM CONVECTIVE FEEDBACK ISSUES. THUS MODELS ARE UNRELIABLE FOR DETAILS. WILL USE A GENERAL BLEND OF MAJOR FEATURES BUT RELY ON NO SPECIFIC MODEL FOR FORECAST. UPPER WAVE ACROSS CO WILL MOVE NE DURING THE DAY TODAY. UPPER WINDS SHOULD BACK THIS MORNING AND CAUSE AREAS OF THUNDERSTORMS TO SHIFT NORTH FOR A WHILE. HOWEVER...BY THIS AFTERNOON EXPECT TSRA TO SHIFT SE ONCE AGAIN AS WAVE GETS CLOSER AND OUTFLOW BOUNDARIES BEGIN TO MOVE SE AS WELL. THUS PLAN TO HAVE POPS ALL DAY ACROSS NWRN FA AND SLOWLY INTRODUCE THEM SE DURING THE DAY...COVERING ROUGHLY THE NWRN HALF OF THE FA BY 00Z. VERY WARM TEMPS IN THE MID LEVELS SHOULD HELP KEEP CONVECTION AT BAY ACROSS SERN FA. THE POPS END UP BEING HIGHER THAN MAV FOR NWRN FA. COULD BE SOME SEVERE WEATHER ACROSS NRN FA PER FAVORABLE WIND PROFILES AND AVAILABLE INSTABILITY. HEAVY RAIN WILL ALSO BE A THREAT WITH GOOD PRECIPITATION EFFICIENCIES AS WELL. TEMPS WILL BE TRICKIER TODAY AS CLOUDS FROM CONVECTION TO THE WEST MAY HELP SLOW TEMP RISE TODAY. HOWEVER ANY SUNSHINE SHOULD BOOST TEMPS QUICKLY...SO WILL KEEP HOT FORECAST TODAY. WILL GO FROM LOWER 90S NWRN FA TO NEAR 100 ACROSS FAR SRN FA...SIMILAR TO THURSDAY/S READINGS. THESE ARE SIMILAR TO MAV/MET NUMBERS MOST AREAS. DEWPOINTS WILL AGAIN BE LOWER ACROSS SRN FA DUE IN PART TO CONTINUED DRY CONDITIONS THERE. THUS HEAT INDEX VALUES LOOK TO REMAIN BELOW ADVISORY CRITERIA. WILL CONTINUE WITH NO HEADLINES BUT WILL HIGHLIGHT IN HWO/SPS. ACTUAL COLD FRONT WILL MOVE INTO THE FA TONIGHT AND KEEP THREAT FOR TSRA ACROSS ENTIRE FA. WENT WITH LIKELY POPS NWRN FA AS TSRA SHOULD BE NUMEROUS ALONG FRONT LIKE TONIGHT. CHANCE POPS LOOK GOOD ELSEWHERE DUE TO TIMING OF FRONT/S ARRIVAL. WENT A LITTLE WARMER THAN MAV WITH CLOUDS AROUND AND NO REAL CHANGE IN AIRMASS. FRONT WILL GRADUALLY EXIT THE FA ON SATURDAY...SO WENT CHANCE POPS ALL AREAS. WITH FRONT AND RAIN AROUND...TEMPS WILL BE COOLER. MAV LOOKS TOO WARM GIVEN FRONT AND CLOUDS ASSOCIATED WITH IT...SO WENT A LITTLE COOLER. NOT SURE THAT SAT EVENING WILL BE DRY ACROSS SRN FA...BUT CONFIDENCE NOT HIGH ENOUGH TO ADD POPS IN DUE TO UNCERTAINTY IN TIMING OF FRONT. DRY WEATHER WILL THEN PERSIST INTO EARLY NEXT WEEK WITH SFC HI PRESSURE IN CONTROL. && .IND WATCHES/WARNINGS/ADVISORIES...NONE && $$ AVIATION...SALLY PUBLIC...CS in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1019 AM EDT FRI AUG 24 2007 .UPDATE... MAINLY UPDATED TO KEEP THE WORDING FRESH. THE THUNDERSTORM ACTIVITY HAS MOVED OUT OF THE COUNTY WARNING AREA FOR THE TIME BEING AND NOT TOO MUCH SHOWER/THUNDERSTORM ACTIVITY GOING ON AT THE MOMENT ON RADARS TO THE WEST. WITH THE FRONT STILL IN THE AREA...SHOWER AND THUNDERSTORM ACTIVITY IS STILL EXPECTED TO INCREASE LATER THIS AFTERNOON/EARLY EVENING TIME FRAME. STORMS WILL BE CAPABLE OF HEAVY RAINFALL AND DAMAGING WINDS. THOSE ARE THE TWO PRIMARY CONCERNS WITH THE STORMS. && .AVIATION... /ISSUED 701 AM EDT FRI AUG 24 2007/ DIFFICULT SHRT TERM FCST. MCS TRAIN STRETCHING FM NW MO INTO NRN IN DIMINISHING RAPIDLY THIS MORNING. HWVR STOUT SW TROUGH EJECTING OUT OF KS WILL REACH SRN GREAT LAKES THIS EVENING. DEEPENING SFC WAVE PASSING NORTHWEST OF TAF SITES SUGGESTS RAPID DESTABILIZATION SHLD OCCUR AGAIN THIS AFTN PRIOR TO CONVECTIVE INITIATION UPSTREAM ACRS IL. BEST GUESS AT TIMING INTO KSBN LOOKS TO BE NR 21Z AND BY 23Z AT KFWA PER 09Z RUC/NSSL 4KM WRF. UPSTREAM MID LVL SPEED MAX UNSEASONABLY STG AND GIVEN DEGREE OF ASCENT AHD OF UPR TROUGH AND XPCD INSTABILITY WILL TEMPO PD OF MVFR IN +TSRA LT AFTN/EVENING W/PREVAILING MVFR CONDS OVERNIGHT. UNTIL THEN VFR LOOKS TO in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 701 AM EDT FRI AUG 24 2007 .AVIATION... DIFFICULT SHRT TERM FCST. MCS TRAIN STRETCHING FM NW MO INTO NRN IN DIMINISHING RAPIDLY THIS MORNING. HWVR STOUT SW TROUGH EJECTING OUT OF KS WILL REACH SRN GREAT LAKES THIS EVENING. DEEPENING SFC WAVE PASSING NORTHWEST OF TAF SITES SUGGESTS RAPID DESTABILIZATION SHLD OCCUR AGAIN THIS AFTN PRIOR TO CONVECTIVE INITIATION UPSTREAM ACRS IL. BEST GUESS AT TIMING INTO KSBN LOOKS TO BE NR 21Z AND BY 23Z AT KFWA PER 09Z RUC/NSSL 4KM WRF. UPSTREAM MID LVL SPEED MAX UNSEASONABLY STG AND GIVEN DEGREE OF ASCENT AHD OF UPR TROUGH AND XPCD INSTABILITY WILL TEMPO PD OF MVFR IN +TSRA LT AFTN/EVENING W/PREVAILING MVFR CONDS OVERNIGHT. UNTIL THEN VFR LOOKS TO SUFFICE. in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 150 PM EDT THU AUG 23 2007 .AVIATION... MAIN ISSUE FOR TAFS WILL BE SHRT/WV OVER IOWA AND ASSOCIATED CONVECTION ON THE IL/IA BORDER AT 1730Z. GFS AND NMM WRF MODELS BOTH PROG CONVECTION TO MOVE NE THROUGH NRN IL INTO LOWER MICHIGAN DESPITE BEST THETA E AND DEWPOINT AXIS WITH A MORE W-E ORIENTATION OVER NRN IL AND NRN IN. BASED ON IR SATELLITE IMAGERY TRENDS...BELIEVE CONVECTION IS MOST LIKELY TO AT LEAST CLIP SBN SO HAVE INCLUDED VCTS IN TAF STARTING AT 23Z. PUT CB IN BOTH SBN AND FWA AS CONVECTION SHOULD BE NEARBY. IF DEVELOPING LINE OF T-STORMS OVER IA TRACKS MORE ERLY OVER RICHER INSTABILITY...WILL NEED TO ADD THUNDER TO FWA. WILL CONTINUE TO MONITOR. OTHER THAN THAT...ADDED GUSTS FOR THIS AFTERNOON AS GOOD MIXING WILL ALLOW HIGHER WINDS TO MIX DOWN TO THE SURFACE. && .UPDATE... UPDATE TO TAKE MORNING WORDING OUT AND REMOVE ALL POPS TILL THIS AFTERNOON AS CONVECTION FROM MCS THIS MORNING HAS MOVED WELL NE. STARTED POPS A FEW HOURS EARLIER THIS AFTERNOON AS RUC40 HINTING AT CONVECTION AS EARLY AS 18Z AND BELIEVE THIS IS POSSIBLE WITH GOOD SKY CLEARING THIS MORNING ALLOWING THE ATMOSPHERE TO HEAT AND DESTABILIZE QUICKLY THIS AFTERNOON. SKY GRIDS TWEAKED DOWN A BIT ALSO AS ONLY A FEW MID AND HIGH LEVEL CLOUDS STICKING AROUND. && .DISCUSSION... PRIMARY FOCUS ON TSRA CHANCES TONIGHT. PAIR OF MCS TO AFFECT PRIMARILY NRN CWA THIS AM. FIRST STRONGEST ACRS NERN CWA ASSOCIATED WITH 5H MID LVL SPEED MAX AROUND 55KT PER KIWX VWP...FURTHER UPSTREAM ANOTHER WEAK EMBEDDED SHORTWAVE WITH KLOT 8-5H PROFILE SLIGHTLY BACKED/STRENGTHENED FLOW. FURTHER SOUTHEAST DEVELOPMENT ON FLANK/TAIL OF LEAD MESOSCALE CONVECTIVE VORTICITY...HOWEVER WITH STABILIZATION OF BL IN WAKE OF FIRST SYSTEM AND MINIMAL EFFECTIVE BULK SHEAR OF 25-30 KTS ANY TSRA TO REMAIN WELL BLO SEVERE LIMITS. THEN A SIGNIFICANT PERIOD OF NO DISCERNIBLE LOW/MID LVL FOCUS FOR TSRA UNTIL STRONG ENERGY DIGGING ACRS INTER-MOUNTAIN REGION INTO WESTERNMOST PORTION OF BROAD 5H TROF EXTENDING ENE TO WRN GRTLKS BECOMES FOCUS FOR UPSTREAM TSRA GENERATION LATE THIS AFTERNOON/EVENING. STRONG LOW LEVEL THERMAL AXIS INTO OHIO VALLEY TO PUSH NWD AND SEE LITTLE REASON TO STRAY FROM MET GUIDANCE IN LWR 90S NORTH TO MID 90S SOUTHERN CWA...MAV SHOWING TYPICAL WARM BIAS OF LATE. SOAKED GROUND/STRONG EVAPOTRANSPIRATIVE RATES THIS AFTERNOON AND SFC DPS ALREADY IN UPPER 60S/LWR 70S TO PUSH HEAT INDEX TO AROUND 100 SOUTHERN CWA...AND WL HIGHLIGHT IN HWO/WEBSTORY. LATER TONIGHT WITH APPROACH OF SHORTWAVE ENERGY...BACKED/STRONG 8H JET TO FOCUS STORM INITIATION ACRS IA/NRN IL LATE AFTERNOON. THEN INTO CWA LATER IN EVENING/OVERNIGHT. AS SHORTWAVE TRANSLATES ENEWD MID TROPOSPHERIC FLOW INCREASES TO AROUND 55KTS ACRS SWRN MI. WITH STRONG HELICAL HODO COMBINED WITH FAVORABLE POOL OF DOWNSTREAM CAPE IN EXCESS OF 3KJ/KG...CONCERN FOR SEVERE STORMS ACRS NRN CWA LATE EVENING/OVERNIGHT. NO MENTION OF SEVERE AND LESSER POPS FURTHER SOUTH AND SOUTHEAST WHERE PROFILES SUPPORT WEAKER DEEP LAYER SHEAR...FURTHER REMOVED FROM LOW LEVEL THETA-E RIDGE/POOL AHEAD OF FRONTAL BOUNDARY TO NORTHWEST AND REMOVED FROM MID LEVEL HEIGHT FALLS FOR FOCUSED ASCENT. SINGLED OUT FRIDAY NIGHT FOR A BIT HIR POPS GIVEN PROXIMITY OF FRONTAL BOUNDARY AND YET ANOTHER VIGOROUS SHORTWAVE MOVING THROUGH MS VLY MEAN TROF. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ ` UPDATE/AVIATION...LAMMERS SHORT TERM...MURPHY LONG TERM....MURPHY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1040 AM EDT THU AUG 23 2007 .UPDATE... UPDATE TO TAKE MORNING WORDING OUT AND REMOVE ALL POPS TILL THIS AFTERNOON AS CONVECTION FROM MCS THIS MORNING HAS MOVED WELL NE. STARTED POPS A FEW HOURS EARLIER THIS AFTERNOON AS RUC40 HINTING AT CONVECTION AS EARLY AS 18Z AND BELIEVE THIS IS POSSIBLE WITH GOOD SKY CLEARING THIS MORNING ALLOWING THE ATMOSPHERE TO HEAT AND DESTABILIZE QUICKLY THIS AFTERNOON. SKY GRIDS TWEAKED DOWN A BIT ALSO AS ONLY A FEW MID AND HIGH LEVEL CLOUDS STICKING AROUND. && .AVIATION... STG LL WAA OVERTOP POST OUTFLW BUBBLE CONTS TO SPRT RENEWED CONVECTIVE DVLPMNT OVR NW/NRN INDIANA ALG NRN EDGE OF TIGHT LL THETA-E GRADIENT. 09Z RUC GOES AGAINST 00Z MODEL SUITE IN KEEPING STG LLJ IN PLACE THROUGH THIS AFTN AND KINDLING STG CONVECTIVE DVLPMNT AGAIN BY 18Z ACRS NW INDIANA AGAIN. BACKDROP SYNOPTIC PATTN REMAINS FVRBL ALTHOUGH CERTAINLY AUGMENTED BY LARGE CONVECTIVE OUTFLW FM TWO EARLIER MCS/S AND ENTIRELY PLAUSIBLE. FOR NOW WILL CONT TO MONITOR NEAR TERM TRENDS UPSTREAM OF WHETHER OR NOT TO CONT A TSRA/CB MENTION AT KSBN. DOUBT KFWA WILL SEE ANYTHING THIS MORNING ALTHOUGH THAT MAY NOT HOLD BY THIS AFTN. SO ATTM WILL PLAY IT OPTIMISTIC AND GO W/VFR CONDS AT BOTH SITES FM 12Z YET HOLD OFF ON ANY POTENTIAL MVFR TSRA MENTION FOR THE AFTN GIVEN HIGH UNCERTAINTY. && .DISCUSSION... PRIMARY FOCUS ON TSRA CHANCES TONIGHT. PAIR OF MCS TO AFFECT PRIMARILY NRN CWA THIS AM. FIRST STRONGEST ACRS NERN CWA ASSOCIATED WITH 5H MID LVL SPEED MAX AROUND 55KT PER KIWX VWP...FURTHER UPSTREAM ANOTHER WEAK EMBEDDED SHORTWAVE WITH KLOT 8-5H PROFILE SLIGHTLY BACKED/STRENGTHENED FLOW. FURTHER SOUTHEAST DEVELOPMENT ON FLANK/TAIL OF LEAD MESOSCALE CONVECTIVE VORTICITY...HOWEVER WITH STABILIZATION OF BL IN WAKE OF FIRST SYSTEM AND MINIMAL EFFECTIVE BULK SHEAR OF 25-30 KTS ANY TSRA TO REMAIN WELL BLO SEVERE LIMITS. THEN A SIGNIFICANT PERIOD OF NO DISCERNIBLE LOW/MID LVL FOCUS FOR TSRA UNTIL STRONG ENERGY DIGGING ACRS INTER-MOUNTAIN REGION INTO WESTERNMOST PORTION OF BROAD 5H TROF EXTENDING ENE TO WRN GRTLKS BECOMES FOCUS FOR UPSTREAM TSRA GENERATION LATE THIS AFTERNOON/EVENING. STRONG LOW LEVEL THERMAL AXIS INTO OHIO VALLEY TO PUSH NWD AND SEE LITTLE REASON TO STRAY FROM MET GUIDANCE IN LWR 90S NORTH TO MID 90S SOUTHERN CWA...MAV SHOWING TYPICAL WARM BIAS OF LATE. SOAKED GROUND/STRONG EVAPOTRANSPIRATIVE RATES THIS AFTERNOON AND SFC DPS ALREADY IN UPPER 60S/LWR 70S TO PUSH HEAT INDEX TO AROUND 100 SOUTHERN CWA...AND WL HIGHLIGHT IN HWO/WEBSTORY. LATER TONIGHT WITH APPROACH OF SHORTWAVE ENERGY...BACKED/STRONG 8H JET TO FOCUS STORM INITIATION ACRS IA/NRN IL LATE AFTERNOON. THEN INTO CWA LATER IN EVENING/OVERNIGHT. AS SHORTWAVE TRANSLATES ENEWD MID TROPOSPHERIC FLOW INCREASES TO AROUND 55KTS ACRS SWRN MI. WITH STRONG HELICAL HODO COMBINED WITH FAVORABLE POOL OF DOWNSTREAM CAPE IN EXCESS OF 3KJ/KG...CONCERN FOR SEVERE STORMS ACRS NRN CWA LATE EVENING/OVERNIGHT. NO MENTION OF SEVERE AND LESSER POPS FURTHER SOUTH AND SOUTHEAST WHERE PROFILES SUPPORT WEAKER DEEP LAYER SHEAR...FURTHER REMOVED FROM LOW LEVEL THETA-E RIDGE/POOL AHEAD OF FRONTAL BOUNDARY TO NORTHWEST AND REMOVED FROM MID LEVEL HEIGHT FALLS FOR FOCUSED ASCENT. SINGLED OUT FRIDAY NIGHT FOR A BIT HIR POPS GIVEN PROXIMITY OF FRONTAL BOUNDARY AND YET ANOTHER VIGOROUS SHORTWAVE MOVING THROUGH MS VLY MEAN TROF. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ ` UPDATE...LAMMERS SHORT TERM...MURPHY LONG TERM....MURPHY AVIATION...HOLSTEN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 702 AM EDT THU AUG 23 2007 .AVIATION... STG LL WAA OVERTOP POST OUTFLW BUBBLE CONTS TO SPRT RENEWED CONVECTIVE DVLPMNT OVR NW/NRN INDIANA ALG NRN EDGE OF TIGHT LL THETA-E GRADIENT. 09Z RUC GOES AGAINST 00Z MODEL SUITE IN KEEPING STG LLJ IN PLACE THROUGH THIS AFTN AND KINDLING STG CONVECTIVE DVLPMNT AGAIN BY 18Z ACRS NW INDIANA AGAIN. BACKDROP SYNOPTIC PATTN REMAINS FVRBL ALTHOUGH CERTAINLY AUGMENTED BY LARGE CONVECTIVE OUTFLW FM TWO EARLIER MCS/S AND ENTIRELY PLAUSIBLE. FOR NOW WILL CONT TO MONITOR NEAR TERM TRENDS UPSTREAM OF WHETHER OR NOT TO CONT A TSRA/CB MENTION AT KSBN. DOUBT KFWA WILL SEE ANYTHING THIS MORNING ALTHOUGH THAT MAY NOT HOLD BY THIS AFTN. SO ATTM WILL PLAY IT OPTIMISTIC AND GO W/VFR CONDS AT BOTH SITES FM 12Z YET HOLD OFF ON ANY POTENTIAL MVFR TSRA MENTION FOR THE AFTN GIVEN HIGH UNCERTAINTY. && .DISCUSSION... PRIMARY FOCUS ON TSRA CHANCES TONIGHT. PAIR OF MCS TO AFFECT PRIMARILY NRN CWA THIS AM. FIRST STRONGEST ACRS NERN CWA ASSOCIATED WITH 5H MID LVL SPEED MAX AROUND 55KT PER KIWX VWP...FURTHER UPSTREAM ANOTHER WEAK EMBEDDED SHORTWAVE WITH KLOT 8-5H PROFILE SLIGHTLY BACKED/STRENGTHENED FLOW. FURTHER SOUTHEAST DEVELOPMENT ON FLANK/TAIL OF LEAD MESOSCALE CONVECTIVE VORTICITY...HOWEVER WITH STABILIZATION OF BL IN WAKE OF FIRST SYSTEM AND MINIMAL EFFECTIVE BULK SHEAR OF 25-30 KTS ANY TSRA TO REMAIN WELL BLO SEVERE LIMITS. THEN A SIGNIFICANT PERIOD OF NO DISCERNIBLE LOW/MID LVL FOCUS FOR TSRA UNTIL STRONG ENERGY DIGGING ACRS INTER-MOUNTAIN REGION INTO WESTERNMOST PORTION OF BROAD 5H TROF EXTENDING ENE TO WRN GRTLKS BECOMES FOCUS FOR UPSTREAM TSRA GENERATION LATE THIS AFTERNOON/EVENING. STRONG LOW LEVEL THERMAL AXIS INTO OHIO VALLEY TO PUSH NWD AND SEE LITTLE REASON TO STRAY FROM MET GUIDANCE IN LWR 90S NORTH TO MID 90S SOUTHERN CWA...MAV SHOWING TYPICAL WARM BIAS OF LATE. SOAKED GROUND/STRONG EVAPOTRANSPIRATIVE RATES THIS AFTERNOON AND SFC DPS ALREADY IN UPPER 60S/LWR 70S TO PUSH HEAT INDEX TO AROUND 100 SOUTHERN CWA...AND WL HIGHLIGHT IN HWO/WEBSTORY. LATER TONIGHT WITH APPROACH OF SHORTWAVE ENERGY...BACKED/STRONG 8H JET TO FOCUS STORM INITIATION ACRS IA/NRN IL LATE AFTERNOON. THEN INTO CWA LATER IN EVENING/OVERNIGHT. AS SHORTWAVE TRANSLATES ENEWD MID TROPOSPHERIC FLOW INCREASES TO AROUND 55KTS ACRS SWRN MI. WITH STRONG HELICAL HODO COMBINED WITH FAVORABLE POOL OF DOWNSTREAM CAPE IN EXCESS OF 3KJ/KG...CONCERN FOR SEVERE STORMS ACRS NRN CWA LATE EVENING/OVERNIGHT. NO MENTION OF SEVERE AND LESSER POPS FURTHER SOUTH AND SOUTHEAST WHERE PROFILES SUPPORT WEAKER DEEP LAYER SHEAR...FURTHER REMOVED FROM LOW LEVEL THETA-E RIDGE/POOL AHEAD OF FRONTAL BOUNDARY TO NORTHWEST AND REMOVED FROM MID LEVEL HEIGHT FALLS FOR FOCUSED ASCENT. SINGLED OUT FRIDAY NIGHT FOR A BIT HIR POPS GIVEN PROXIMITY OF FRONTAL BOUNDARY AND YET ANOTHER VIGOROUS SHORTWAVE MOVING THROUGH MS VLY MEAN TROF. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...MURPHY LONG TERM....MURPHY AVIATION...HOLSTEN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL ISSUED BY NATIONAL WEATHER SERVICE LA CROSSE WI 341 PM CDT FRI AUG 24 2007 .SYNOPSIS... AT 3 PM...A SURFACE COLD FRONT WAS MOVING SLOWLY SOUTHEAST INTO EAST CENTRAL IOWA. SCATTERED SHOWERS WERE LOCATED ALONG THIS FRONT. LOOKING FURTHER TO THE WEST...AN AREA OF SHOWERS AND THUNDERSTORMS WAS LOCATED ACROSS EASTERN NEBRASKA AND EASTERN KANSAS. THIS WAS ASSOCIATED WITH A SHORT WAVE TROUGH THAT WILL BE MOVING EAST THROUGH THE MID MISSISSIPPI RIVER VALLEY TONIGHT. && .SHORT TERM...TONIGHT THROUGH SUNDAY BOTH SPC MESO ANALYSIS TOOL AND AWIPS LAPS DATA...CONTINUE TO SHOW THAT A MOST UNSTABLE CAPE AXIS IS STILL LOCATED ALONG A KORD-KSTL-KSGF LINE. NORTH OF THIS LINE THE MOST UNSTABLE CAPES ARE LESS THAN 500 J/KG. MEANWHILE SOUTH OF THIS LINE...THE MOST UNSTABLE CAPES RANGE FROM 1000 TO 3000 J/KG. THE 18Z RUC FORECASTS SUGGESTS THAT THIS WILL CHANGE LITTLE THROUGH TONIGHT. AS A RESULT...THE BEST CHANCE OF HEAVY RAINS LOOKS TO BE ALONG AND SOUTH OF HIGHWAY 30. WITH THE SOILS SATURATED AND RIVERS EITHER FLOODING OR HIGH...I KEPT THE FLASH FLOOD WATCH UP THOUGH TONIGHT. ON SATURDAY...ALL OF THE AUGUST 24TH 12Z MODELS ARE IN VERY GOOD AGREEMENT THAT AN UPPER LEVEL TROUGH WILL MOVE ACROSS EASTERN IOWA...NORTHERN ILLINOIS...AND NORTHEAST MISSOURI. EVEN THOUGH THIS IS THE CASE...THEY DO DIFFER ON WHETHER ANY PRECIPITATION WILL FALL ACROSS THE REGION. WITH THE THE GFS DRYING THE SURFACE DEW POINTS TO AROUND 60F. ITS 0-3 KM CAPES REMAIN GENERALLY LESS THAN 500 J/KG. MEANWHILE THE NAM/WRF STILL HAS DEW POINTS IN THE MID 60S. THIS RESULTS IN THE 0-3KM CAPES CLIMBING INTO THE 1000 TO 2000 J/KG RANGE. CONSIDERING THE WEAK SURFACE WINDS AND THE AMOUNT OF PRECIPITATION THAT HAS FALLEN ACROSS THE REGION DURING THE PAST COUPLE OF WEEKS...I AM MORE INCLINED TO BELIEVE THE NAM/WRF DEW POINTS AND THERE WILL BE ENOUGH INSTABILITY TO INCLUDE A 20 TO 30 PERCENT CHANCE OF SHOWERS. HIGH PRESSURE BOTH AT THE SURFACE AND ALOFT WILL PROVIDE ENOUGH SUBSIDENCE THAT SKIES WILL RANGE FROM PARTLY CLOUDY TO MOSTLY CLEAR. WITH 850 MB TEMPERATURES RUNNING BETWEEN 13 AND 15C... SURFACE TEMPERATURES WILL RANGE FROM 75 TO 80 DEGREE RANGE ACROSS EASTERN IOWA AND NORTHERN ILLINOIS...AND IN THE LOWER AND MIDDLE 80S ACROSS NORTHWEST MISSOURI. .LONG TERM...SUNDAY NIGHT THROUGH FRIDAY ALL OF THE AUGUST 24TH 12Z ARE IN GOOD AGREEMENT THAT THE BEST 850 MB MOISTURE TRANSPORT ON THE BACK OF THE RIDGE WILL BE LOCATED ACROSS CENTRAL AND PARTS OF NORTHEAST IOWA ON SUNDAY NIGHT AND MONDAY. THIS SYNOPTIC SITUATION TYPICALLY RESULTS IN THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS DURING THE OVERNIGHT AND EARLY MORNING. I CONSIDERED ADDING A SMALL CHANCE OF PRECIPITATION ACROSS EAST CENTRAL IOWA...BUT SINCE IT IS STILL QUESTIONABLE HOW FAR EAST THE MOISTURE TRANSPORT WILL GET I KEPT THE FORECAST DRY FOR NOW. BESIDES THIS PERIOD...THE NEXT CHANCE OF PRECIPITATION LOOKS TO BE FROM TUESDAY INTO WEDNESDAY AS A CANADIAN COLD FRONT MOVES SLOWLY SOUTHEAST THROUGH THE REGION. && .AVIATION... AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE AREA THROUGH THE EVENING AND OVERNIGHT HOURS PRODUCING SCATTERED SHRA AND TSRA THROUGH DAYBREAK SATURDAY AS A COLD FRONT SLOWLY PUSHES TO THE SOUTHEAST. PREVAILING CIGS WILL REMAIN BETWEEN 1000 AND 3000 FT WITH VSBYS P6SM. THESE WILL OCCASIONALLY DROP TO AROUND 700 FT WITH VSBYS AROUND 1SM IN SHRA/TSRA. CID AND DBQ WILL BE FIRST AREA TO SEE PCPN END...BUT LINGERING MOISTURE WILL RESULT IN A LOW STRATUS DECK AND FOG THROUGH THE MORNING HOURS SATURDAY. ..14.. && .HYDROLOGY TODAY HAS BEEN A TRULY INCREDIBLE DAY OF HYDRO ACROSS THE CWA. A 5 TO 7 INCH RAINFALL EVENT OCCURRED BETWEEN MIDNIGHT AND 8 AM TODAY. THIS ON TOP OF VERY SATURATED GROUND HAS PRODUCED FLASH FLOODING...AND FLASH FLOOD RESPONSES ON SOME AREA RIVERS. RIVER RISES SKYROCKETED TO MAJOR FLOOD STAGE EARLY THIS MORNING ON THE DES MOINES RIVER...AND LATER ON THE FOX RIVER. LEVELS PEAKED QUICKLY IN SOME CASES...LIKE IN KEOSAUQUA...AND ARE NOW CRESTING BELOW RECORD VALUES. MOST OTHER RIVERS ARE EXPERIENCING MINOR TO MODERATE FLOODING...WITH SOME MAJOR FLOODING ON THE ROCK AND LOWER MISSISSIPPI...INCLUDING BURLINGTON. MOST RIVERS SHOULD CREST BETWEEN LATE TONIGHT AND EARLY NEXT WEEK. PLEASE REFERENCE INDIVIDUAL POINT FORECASTS ON THE AHPS/RIVER INFO SECTION ON THE WWW.CRH.NOAA.GOV/DVN WEB PAGE. ..ERVIN.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR CEDAR-CLINTON-DES MOINES-HENRY IA-IOWA-JEFFERSON-JOHNSON-KEOKUK-LEE-LOUISA- MUSCATINE-SCOTT-VAN BUREN-WASHINGTON. IL...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR BUREAU-HANCOCK- HENDERSON-HENRY IL-MCDONOUGH-MERCER-PUTNAM-ROCK ISLAND- WARREN-WHITESIDE. MO...FLASH FLOOD WATCH THROUGH LATE TONIGHT FOR CLARK-SCOTLAND. && $$ BAUMGARDT/BOYNE/14/ERVIN ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1119 AM CDT THU AUG 23 2007 .UPDATE... ISENTROPIC LIFT IN THE 320K LAYER HAS LEAD TO SOME ELEVATED SHRA ACROSS SOUTH CENTRAL AND CENTRAL KANSAS. DID NOTE A FEW LIGHTNING STRIKES AS MID LEVEL LAPSE RATES ARE STEEP ENOUGH FOR SOME TSRA. LATEST SHORT TERM RUC MODEL SHOWS THIS AREA OF LIFT SLOWLY MOVING TO THE EAST AND WEAKENING DURING THE MIDDAY. SO EXPECT THIS AREA OF SHRA/TSRA TO DECREASE AS THE AFTERNOON PROGRESSES WITH A RETURN OF SOME SUNSHINE. AFTER SUNSHINE RETURNS THE SURAFCE WINDS COULD GET RATHER GUSTY...ESPECIALLY ACROSS SOUTH CENTRAL KANSAS AS 40-45KT 850H WINDS MIX DOWN TO THE SURFACE. SO WILL CONTINUE WITH WIND ADVISORY IN THIS AREA. AM A LITTLE CONCERNED ABOUT AREAS JUST SOUTH OF THE AOBVE MENTIONED BOUNDARIES GUSTING TO 45 KT AS WELL...BUT WILL NOT EXPAND ADVISORY YET. ATTENTION THEN TURNS TO THIS EVENING...AS FRONTAL BOUNDARY AND OUTFLOW BOUNDARY REMNANTS DRAPED ACROSS CENTRAL AND NORTH CENTRAL KANSAS BECOME THE FOCUS FOR CONVECTION. THE MID-MORNING CLOUDS AND SHRA...WILL ACT TO KEEP CONVECTION CHANCES AT BAY FOR MOST OF THE AFTERNOON AS LOW LEVEL MOISTURE AND INSTABILITY INCREASES ALONG THE BOUNDARIES. SHORT RANGE MODELS SUGGEST ENVIRONMENT IN NORTH CENTRAL KANSAS BECOMES UNCAPPED BY THE EARLY EVENING HOURS...SO EXPECT CONVECTION TO DEVELOP BETWEEN 22-00Z JUST TO THE NORTHWEST OF CENTRAL KS. 0-3KM SHEAR VALUES ACROSS CENTRAL KS OF 25-35KTS SUGGEST A DAMAGING WIND AND HAIL THREAT...WITH NAM FORECAST SOUNDINGS SHOWING AN INVERTED-V PROFILE FAVORABLE FOR DOWNBURST WINDS. SO LIKELY POPS AND SPC SLIGHT RISK LOOKS WARRANTED. EXPECT THIS CONVECTION TO SLOWLY PROPAGATE INTO MOST OF CEN KS LATE THIS EVENING. .AVIATION... FOR 18Z TAF SUITE. ISENTROPIC LIFT ACROSS THE AREA HAS LEAD TO AN LARGE EXPANSE OF ALTO-CU ACROSS THE REGION. SOME ELEVATED INSTABILITY HAS ALSO LEAD SOME VCTS NEAR KHUT AND KICT. SO MAY HAVE TO CARRY SOME VCTS FOR THIS AREA FOR A COUPLE OF HOURS (FROM 18-20Z). EXPECT VFR CONDITIONS EVEN WITH THE VCTS CHANCE AS THE CLOUD DECK IS 8-10K FEET. TSRA CHANCES THEN WILL SHIFT TO CEN KS THIS EVENING NEAR KRSL INITIALLY AND THEN TO KSLN AND KHUT/KICT. SO WILL KEEP VCTS AND TSRA GOING IN KRSL TAF SITES...BUT FEEL THAT SOME VCTS SHOULD BE ADDED TO KSLN/KICT AND KHUT AS WELL AS CONVECTION BEGINS TO PROPAGATE SOUTHEAST AS THE OVERNIGHT PROGRESSES. COULD ALSO SEE SOME MVFR CEILINGS IN AND NEAR THE CONVECTION. KETCHAM && .PREV DISCUSSION... /ISSUED 652 AM CDT THU AUG 23 2007/ UPDATE... AVIATION... 12Z TAF SET: [KRSL/KHUT/KSLN/KICT/KCNU] WITH SFC LOW STRENGTHENING OVER SE CO SOUTHERLY LWR-LEVEL WINDS TO INCREASE MARKEDLY ACROSS SC KS WHERE WIND ADVISORY IS IN EFFECT THIS AFTERNOON. SUSTAINED SPEEDS ~30KTS WITH GUSTS ~40KTS ARE LIKELY AT KICT & KHUT FROM 17Z-02Z. SOUTHERLY WINDS OF 22G35KTS ARE LIKELY AT KRSL & KSLN THIS AFTERNOON WITH WINDS DIMINISHING LATE THIS AFTERNOON @ KRSL WHERE CLOSER TO AN APPROACHING COLD FRONT. THE COLD FRONT IS DRAWING CONSIDERABLE ATTENTION FOR SEVERAL REASONS: 1) HIGH CONVECTIVE POTENTIAL (ESPECIALLY AT KRSL) 2) TIMING OF WIND SHIFT & 3) POTENTIAL FOR SPREADING OF MVFR CEILINGS & VISIBILITIES INTO KRSL ~05Z. TSRA SHOULD SPREAD SE TOWARD KHUT & KSLN EARLY FRI MORNING BUT UNTIL ARRIVAL TIME OF COLD FRONT COMES INTO BETTER FOCUS HAVE LEFT "TSRA" DESCRIPTOR OUT OF THESE TERMINALS FOR TIME BEING. PREV DISCUSSION... /ISSUED 303 AM CDT THU AUG 23 2007/ DISCUSSION... MAIN FORECAST CONCERNS ARE THUNDERSTORM CHANCES OVER THE NEXT FEW DAYS AND STRONG WINDS TODAY. TODAY-TONIGHT: SYNOPTIC FRONTAL BOUNDARY FAIRLY DIFFUSE AT 06Z WITH IMPACTS FROM CONVECTIVE OUTFLOWS FROM VARIOUS T-STORM CLUSTERS OVERNIGHT. HOWEVER IT LOOKS TO EXTEND ROUGHLY FROM NW KS INTO SERN NE. A LEAD SHORTWAVE CAN READILY BE SEEN EARLY THIS AM (VIA WIND PROFILERS/SATELLITE) LIFTING OUT ACROSS WESTERN NE/WESTERN KS AND IS AIDING A T-STORM CLUSTER OVER N-CENTRAL KS. AS THIS WAVE LIFTS NEWD TO IOWA/N MISSOURI BY LATE THIS PM...THE FRONT SHOULD GET A SOUTHWARD NUDGE REACHING CENTRAL/SOUTHWESTERN KS TONIGHT. AHEAD OF THE FRONT...THE NAM- WRF/GFS AGREE THE PRESSURE GRADIENT WILL TIGHTEN UP OVER SOUTHERN KS WITH VERY STEEP 1000-850 LAPSE RATES AIDING STRONG MIXING. CURRENT AREA PROFILERS AND PROGGED BOUNDARY LAYER-850 WINDS ARE SUPPORTIVE OF POTENTIAL ADVISORY CRITERIA SOUTHERLY WINDS IN SOUTH CENTRAL KS. HAVE COORDINATED WITH WFO`S DDC/OUN ON A WIND ADVISORY RUNNING FROM 17Z-00Z FOR S-CNTRL KS. THINKING CURRENT T-STORM CLUSTER MOVING INTO N-CENTRAL KS SHOULD AFFECT SOME OF OUR CENTRAL KS COUNTIES EARLY-MID MORNING. STRONG HEATING/INSTABILITY/CONVERGENCE NEAR THE APPROACHING COLD FRONT WILL LEAD TO A CHANCE OF T-STORMS THIS PM IN CENTRAL KS. ALSO THE POSSIBILITY OF A REMNANT CONVECTIVE OUTFLOW BOUNDARY JUST SOUTHEAST OF THE FRONT WHICH COULD PLAY A MESOSCALE ROLE THIS PM. STRONG INSTABILITY AND 0-6KM SHEAR OF 35-45KT SUPPORTIVE OF A FEW ORGANIZED SEVERE STORMS IN CENTRAL KS LATE THIS PM/EVE. SEVERAL FACTORS CONTINUE TO SUPPORT MCS DEVELOPMENT/EVOLUTION OVER THE NW HALF OF THE STATE TONIGHT: A SOUTH-SOUTHWESTERLY 50 KT LOW- LEVEL JET WITH VERY STRONG MOISTURE TRANSPORT...RIGHT REAR QUAD OF UPPER JET...AND 850 FN CONVERGENCE ALONG THE FRONT. HIGHEST POPS TARGET CENTRAL KS IN OUR AREA TAPERING TO SLIGHT CHANCE IN THE SOUTHEAST COUNTIES WHO MAY NOT GET ANY RAIN TONIGHT. FRIDAY-SATURDAY: SHORTWAVE TROF DIGGING ACROSS THE PACIFIC NW EARLY THIS AM...WILL SWEEP ACROSS THE NORTH CENTRAL STATES FRIDAY-FRIDAY NIGHT...GIVING THE COLD FRONT YET ANOTHER SURGE. THE MODELS PUSH THE BOUNDARY TO ABOUT THE KS/OK BORDER BY 12Z SATURDAY BEFORE THEY STALL IT OUT. GIVEN CONCERNS ABOUT SIGNIFICANT CLOUD COVER POSSIBLY IMPACTING HEATING IN PART DUE TO MCS DEBRIS...ALONG WITH POST-FRONTAL CLOUDS...NOT PLANNING TO CARRY ABOVE 50% POPS FOR MOST OF THE AREA FRI-FRI NIGHT. ALSO...THE UPPER SUPPORT FRI NIGHT DOES NOT LOOK AS GOOD AS TONIGHT. A LINGERING SLIGHT CHANCE OF THUNDER IS REASONABLE SATURDAY IN OUR SOUTHERN KS COUNTIES WITH THE STALLED FRONT IN THE AREA AND DIURNAL INSTABILITY/MOISTURE POOLING PROGGED. HIGHS FRI STILL LOOK PROBLEMATIC WITH A DECENT TEMPERATURE CONTRAST POSSIBLE WITH THE FRONT IN OUR AREA. WILL SHOOT FOR LOWER 80S BEHIND FRONT IN CENTRAL KS...TO MID 90S IN THE FAR SE. SUNDAY-WEDNESDAY: NO SIGNIFICANT CHANGES MADE TO THESE PERIODS. MODELS IN AGREEMENT THAT UPPER RIDGING WILL TRY TO AT LEAST TEMPORARILY BUILD BACK ACROSS THE SOUTHERN PLAINS...WITH RETURN SOUTHERLY FLOW OVER THE AREA LEADING TO ABOVE NORMAL HIGHS. NEXT FRONT DUE INTO THE AREA LATE TUES INTO WED IN ASSOCIATION WITH AN UPPER TROF LIFTING FROM THE PACIFIC NW ACROSS THE NORTHERN PLAINS. SLIGHT CHANCE T-STORMS LOOKING VERY REASONABLE IN OUR AREA WITH THIS FRONT. JMC AVIATION... FOR 06Z TAFS...IN THE SHORT TERM MAIN AVIATION CONCERN REMAINS CONVECTIVE POTENTIAL OVER CENTRAL KS. THE STORMS OVER NE KS HAVE HAD TROUBLE WORKING WEST. THEREFORE IT APPEARS THE BEST SHOT AT STORMS OVER CENTRAL KS WILL COME FROM STORMS THAT DEVELOP OUT WEST AND WORK INTO THE AREA. WITH ANOTHER UPPER WAVE LIFTING OUT ACROSS THE HIGH PLAINS...STORMS ARE ALREADY FIRING ACROSS GLD`S FORECAST AREA AND ARE TRACKING EAST. THEREFORE JUST KEPT THE VCTS IN AT RSL WITH JUST A MENTION OF CB IN THE CLOUD GROUP AT SLN. THE MAIN STORY DURING THE DAY THU WILL BE THE WINDY CONDITIONS. CONFIDENCE IS HIGH THAT SW WINDS WILL BE SUSTAINED BETWEEN 20 AND 30 MPH WITH GUSTS TO AROUND 35 MPH. ICT...HUT AND SLN HAVE THE BEST SHOT AT SEEING WINDS CLOSE TO ADVISORY CRITERIA THU AFTERNOON. CHANCES FOR STORMS WILL INCREASE THU NIGHT AS THE FRONT...THAT HAS BROUGHT NUMEROUS STORMS OVER NEBRASKA...SAGS SOUTH INTO NORTH CENTRAL KS. THEREFORE IT LOOKS LIKE RSL AND SLN WILL HAVE A SHOT AT STORMS FIRST THU NIGHT WITH CHANCES SPREADING SOUTH INTO FRI MORNING. && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 93 74 88 70 / 20 30 40 50 HUTCHINSON 94 72 87 67 / 20 40 50 40 NEWTON 93 74 87 67 / 20 30 50 40 ELDORADO 93 74 88 70 / 20 30 40 50 WINFIELD-KWLD 93 75 90 71 / 10 20 40 50 RUSSELL 96 65 82 65 / 40 60 60 20 GREAT BEND 96 66 83 66 / 30 50 60 20 SALINA 94 68 84 66 / 40 50 60 20 MCPHERSON 94 71 85 67 / 30 40 50 30 COFFEYVILLE 94 74 93 71 / 10 20 30 50 CHANUTE 94 74 90 70 / 10 20 40 50 IOLA 94 73 89 69 / 10 20 40 50 PARSONS-KPPF 94 74 92 71 / 10 20 40 50 && .ICT WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 7 PM CDT THIS EVENING FOR KSZ067>069-082-083- 091>093. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1125 PM EDT FRI AUG 24 2007 .UPDATE... UPDATED TO ADD ISOLD -SHRA OVER THE FAR SCNTRL AS RADAR SHOWS SOME -SHRA HAVE DVLPD OVER MARINETTE COUNTY IN WI. THESE SHRA APPEAR FAIRLY SHALLOW...HAVING DVPLD IN MOIST LYR TO H725 AS SHOWN ON 00Z GRB SDNG. SINCE THE STEERING FLOW IN THIS LYR IS NNE... THINK THE ONLY PLACE IN THE CWA THAT MIGHT BE IMPACTED WOULD BE SRN MNM COUNTY IF THE LLVL FLOW BACKS MORE NW LATER AS FCST BY RECENT RUC. ALSO BUMPED UP FCST LO TEMPS A COUPLE OF DEGREES TO ACCOUNT FOR THIS MORE RESILIENT MSTR AND TREND ON STLT IMAGERY FOR BACK EDGE OF LINGERING CLD TO SLOW RETREAT TO THE S. COORDINATED WITH GRB. KC .SYNOPSIS...FGEN RAIN BAND OVER CENTRAL WI SHOWING SIGNS OF WEAKENING AS NOTED ON RADAR LOOP. ISOLD SHRA FROM THIS BAND STILL ADVECTING OVER MNM COUNTY WITH EVENING SCT SPRINKLES NOTED OVER ALGER-DELTA COUNTY EASTWARD. EXPECT THESE LIGHT SHOWERS TO END BY 00Z WITH LOSS OF FGEN FORCING PER 18Z RUC. INSOLATION OVER WRN COUNTIES HAS LEAD TO DIURNAL CU FORMATION AS NOTED ON VISIBLE SATELLITE IMAGERY. EXPECT THESE CLOUDS TO GENERALLY DISSIPATE AFTER SUNSET. ANOTHER SHORTWAVE NOTED OVER THE DAKOTAS ON WATER VAPOR LOOP IS DUE TO MOVE INTO THE WESTERN GREAT LAKES ON SAT. .SHORT TERM (TONIGHT AND SAT)... CONCERNS FOCUS ON CLOUDS/TEMPS TONIGHT AND THEN POTENTIAL FOR ANY PCPN ON SAT WITH UPSTREAM SHORTWAVE OVER THE DAKOTAS. EXPECT CLEARING LINE FROM FGEN CLOUDS/PCPN TO CONTINUE TO GRADUALLY PROGRESS EASTWARD ACROSS THE REST OF THE CWA AS FGEN BAND SAGS E. ANY CLEARING MAY BE TEMPORARY THOUGH AS CLOUDS IN ADVANCE OF APPROACHING SHORTWAVE FROM THE DAKOTAS SPREADS IN FROM THE WEST. USED A BLEND OF GFS AND NAM MOS GUIDANCE FOR MIN TEMPS. EXPECT THEIR WILL BE ENOUGH CLEARING/RAD COOLING OVER THE WESTERN INTERIOR THIS EVENING TO DROP A FEW LOCATIONS INTO THE MID-UPR 40S. THE REST OF THE CWA SHOULD STAY IN THE LOW TO MID 50S. THERE ARE SOME MODEL TIMING DIFFERENCES WITH APPROACHING SHORTWAVE FROM THE NORTHERN PLAINS. THE UKMET AND REGIONAL CANADIAN APPEAR TO BE QUICKEST WITH THE SHORTWAVE...MOVING IT THROUGH UPR MI IN THE MORNING HRS. THE SLOWER NAM SHOWS THE SHORTWAVE MOVING THROUGH IN THE AFTERNOON WHILE THE GFS APPEARS TO BE SOMEWHERE IN BETWEEN. THE TIMING COULD BE CRITICAL ON ANY RAIN CHANCES FOR OUR AREA ON SAT. IF THE SHORTWAVE AND ASSOC COLD POOL MOVES THROUGH IN THE AFTERNOON DURING PEAK HEATING HOURS...THERE COULD BE A BETTER CHANCE OF SHRA. NAM AND GFS SNDGS INDICATE AROUND 100 J/KG CAPE BY EARLY AFTERNOON WITH DEWPOINTS IN THE LOWER 50S BUT IF THE UKMET AND REG CANADIAN VERIFY THEN THIS MARGINAL INSTABILITY MAY NOT BE REALIZED. FOR NOW...HAVE DECIDED TO TREND TOWARD AN INCREASE CLOUDS IN THE MORNING/EARLY AFTERNOON HRS BUT LEAVE THE FORECAST DRY. BOTH GFS AND NAM SHOW GOOD DRYING/SUBSIDENCE BY LATE AFTERNOON IN THE WAKE OF THE SHORTWAVE. .LONG TERM (SAT NIGHT THROUGH NEXT FRI)... SHORTWAVE RIDGING TAKES SHAPE FOR SAT NIGHT INTO SUN. CLEARING SKIES...DRY AIR...AND LIGHT WINDS SUPPORT MOS MINS INTO THE LOWER 40S SAT NIGHT. LIKE THE IDEA FM PREVIOUS SHIFT OF LOWERING TEMPS TOWARD COOP MOS. THESE GRIDS ALONG WITH GFS BIAS ADJUSTED GRIDS POINT TO LOWS IN UPR 30S/AROUND 40 IN THE COOLEST INTERIOR SPOTS. MAX TEMPS STEADILY RISE FM COOLER TEMPS THIS WEEKEND. H85 WINDS BACK MORE SW LATER SUN INTO MON ALLOWING WARMER AIR OVER BUILDING OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS EARLY IN THE WEEKEND TO MOVE INTO UPR LAKES. OUTSIDE OF GFS PROGS SHOWING +20C H85 TEMPS OVR CWA ON MON...MOST OTHER GUIDANCE SETTLES ON H85 TEMPS AROUND +16C...WHICH RESULTS IN MAX TEMPS MONDAY INTO THE LOW-MID 80S. BELIEVE GFS IS TOO AGGRESSIVE WITH WARMING...PROBABLY DUE TO MUCH MORE WRAPPED UP SFC LOW IT SHOWS RIDING NE ALONG SFC FRONT. ZONAL FLOW PROCEEDS TO PROPEL THIS COLD FRONT ACROSS UPR GREAT LAKES BY WED. TIMING OF THE FRONT STILL UNCERTAIN. GFS/CANADIAN INDICATES FRONT IS ALREADY THROUGH CWA BY 00Z WED. MEANWHILE...GFS ENSEMBLE AND OPERATIONAL 00Z/12Z ECMWF ARE 6-12 HR SLOWER...DUE IN PART TO A MORE INVERTED TROUGH LOOK. AT THIS POINT...PREFER THE SLOWER SOLUTION WHICH IS ALSO MORE IN STEP WITH LATEST HPC PROGS. BETTER CHANCES OF RAIN THROUGH TUE ARE JUST TO THE WEST INTO THE WEST HALF OF CWA. STILL...SLIGHTLY BETTER PCPN CHANCES WILL EVEN MAKE IT INTO EAST CWA BY TUE NIGHT. ALL RAIN SHOULD BE DONE BY 12Z WED. THEN ...MORE DRY WEATHER RIGHT INTO THE END OF NEXT WEEK AS A LARGE HIGH BUILDS ACROSS THE REGION THU/FRI. GUIDANCE/HPC HIGHS LOOKED FINE AFTER THE FROPA BUT DID LOWER AFTN DEWPOINTS AND OVERNIGHT LOWS WITH THE EXPECTED DRY AIRMASS. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... PLAN ON VFR CONDITIONS THIS FCST PD WITH SOMEWHAT DRIER AIR TO THE WNW AS SHOWN ON RECENT TAMDAR SDNG FM DLH STREAMING INTO THE FA. SHRTWV APRCHG FM THE SW LATE TNGT/SAT IN MORE SW FLOW ALF WL CAUSE QUITE A BIT OF SC...BUT EXPECT NO PCPN OR CIGS LESS THAN 3000 FT ATTM WITH RELATIVELY DRY LLVLS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT FAIRLY LIGHT WINDS OVER LAKE SUPERIOR THROUGH SUN MORNING (REALLY NOTHING OVER 20KT). WINDS WILL STRENGTHEN LATER SUN THROUGH MON NIGHT AS PRES GRADIENT TIGHTENS BETWEEN HIGH PRES OVER NEW ENGLAND AND A COLD FRONT APPROACHING FROM THE NORTHERN PLAINS. SHOULD SEE SOUTHERLY 15-25KT WINDS DEVELOP OVER THE E HALF OF LAKE SUPERIOR SUN EVENING AND PERSIST THROUGH MON NIGHT. WINDS WILL BE LIGHTER OVER THE W HALF OF THE LAKE AS THEY COMMONLY ARE IN A SOUTHERLY FLOW. THE COLD FRONT IS EXPECTED TO CROSS THE LAKE LATE TUE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ SYNOPSIS/SHORT TERM/MARINE...VOSS LONG TERM...JLA AVIATION...KC UPDATE...KC mi AREA FORECAST DISCUSSION...UPDATED FOR AVIATION NATIONAL WEATHER SERVICE MARQUETTE MI 740 PM EDT FRI AUG 24 2007 .SYNOPSIS...FGEN RAIN BAND OVER CENTRAL WI SHOWING SIGNS OF WEAKENING AS NOTED ON RADAR LOOP. ISOLD SHRA FROM THIS BAND STILL ADVECTING OVER MNM COUNTY WITH EVENING SCT SPRINKLES NOTED OVER ALGER-DELTA COUNTY EASTWARD. EXPECT THESE LIGHT SHOWERS TO END BY 00Z WITH LOSS OF FGEN FORCING PER 18Z RUC. INSOLATION OVER WRN COUNTIES HAS LEAD TO DIURNAL CU FORMATION AS NOTED ON VISIBLE SATELLITE IMAGERY. EXPECT THESE CLOUDS TO GENERALLY DISSIPATE AFTER SUNSET. ANOTHER SHORTWAVE NOTED OVER THE DAKOTAS ON WATER VAPOR LOOP IS DUE TO MOVE INTO THE WESTERN GREAT LAKES ON SAT. .SHORT TERM (TONIGHT AND SAT)... CONCERNS FOCUS ON CLOUDS/TEMPS TONIGHT AND THEN POTENTIAL FOR ANY PCPN ON SAT WITH UPSTREAM SHORTWAVE OVER THE DAKOTAS. EXPECT CLEARING LINE FROM FGEN CLOUDS/PCPN TO CONTINUE TO GRADUALLY PROGRESS EASTWARD ACROSS THE REST OF THE CWA AS FGEN BAND SAGS E. ANY CLEARING MAY BE TEMPORARY THOUGH AS CLOUDS IN ADVANCE OF APPROACHING SHORTWAVE FROM THE DAKOTAS SPREADS IN FROM THE WEST. USED A BLEND OF GFS AND NAM MOS GUIDANCE FOR MIN TEMPS. EXPECT THEIR WILL BE ENOUGH CLEARING/RAD COOLING OVER THE WESTERN INTERIOR THIS EVENING TO DROP A FEW LOCATIONS INTO THE MID-UPR 40S. THE REST OF THE CWA SHOULD STAY IN THE LOW TO MID 50S. THERE ARE SOME MODEL TIMING DIFFERENCES WITH APPROACHING SHORTWAVE FROM THE NORTHERN PLAINS. THE UKMET AND REGIONAL CANADIAN APPEAR TO BE QUICKEST WITH THE SHORTWAVE...MOVING IT THROUGH UPR MI IN THE MORNING HRS. THE SLOWER NAM SHOWS THE SHORTWAVE MOVING THROUGH IN THE AFTERNOON WHILE THE GFS APPEARS TO BE SOMEWHERE IN BETWEEN. THE TIMING COULD BE CRITICAL ON ANY RAIN CHANCES FOR OUR AREA ON SAT. IF THE SHORTWAVE AND ASSOC COLD POOL MOVES THROUGH IN THE AFTERNOON DURING PEAK HEATING HOURS...THERE COULD BE A BETTER CHANCE OF SHRA. NAM AND GFS SNDGS INDICATE AROUND 100 J/KG CAPE BY EARLY AFTERNOON WITH DEWPOINTS IN THE LOWER 50S BUT IF THE UKMET AND REG CANADIAN VERIFY THEN THIS MARGINAL INSTABILITY MAY NOT BE REALIZED. FOR NOW...HAVE DECIDED TO TREND TOWARD AN INCREASE CLOUDS IN THE MORNING/EARLY AFTERNOON HRS BUT LEAVE THE FORECAST DRY. BOTH GFS AND NAM SHOW GOOD DRYING/SUBSIDENCE BY LATE AFTERNOON IN THE WAKE OF THE SHORTWAVE. .LONG TERM (SAT NIGHT THROUGH NEXT FRI)... SHORTWAVE RIDGING TAKES SHAPE FOR SAT NIGHT INTO SUN. CLEARING SKIES...DRY AIR...AND LIGHT WINDS SUPPORT MOS MINS INTO THE LOWER 40S SAT NIGHT. LIKE THE IDEA FM PREVIOUS SHIFT OF LOWERING TEMPS TOWARD COOP MOS. THESE GRIDS ALONG WITH GFS BIAS ADJUSTED GRIDS POINT TO LOWS IN UPR 30S/AROUND 40 IN THE COOLEST INTERIOR SPOTS. MAX TEMPS STEADILY RISE FM COOLER TEMPS THIS WEEKEND. H85 WINDS BACK MORE SW LATER SUN INTO MON ALLOWING WARMER AIR OVER BUILDING OVER THE NORTHERN ROCKIES AND NORTHERN PLAINS EARLY IN THE WEEKEND TO MOVE INTO UPR LAKES. OUTSIDE OF GFS PROGS SHOWING +20C H85 TEMPS OVR CWA ON MON...MOST OTHER GUIDANCE SETTLES ON H85 TEMPS AROUND +16C...WHICH RESULTS IN MAX TEMPS MONDAY INTO THE LOW-MID 80S. BELIEVE GFS IS TOO AGGRESSIVE WITH WARMING...PROBABLY DUE TO MUCH MORE WRAPPED UP SFC LOW IT SHOWS RIDING NE ALONG SFC FRONT. ZONAL FLOW PROCEEDS TO PROPEL THIS COLD FRONT ACROSS UPR GREAT LAKES BY WED. TIMING OF THE FRONT STILL UNCERTAIN. GFS/CANADIAN INDICATES FRONT IS ALREADY THROUGH CWA BY 00Z WED. MEANWHILE...GFS ENSEMBLE AND OPERATIONAL 00Z/12Z ECMWF ARE 6-12 HR SLOWER...DUE IN PART TO A MORE INVERTED TROUGH LOOK. AT THIS POINT...PREFER THE SLOWER SOLUTION WHICH IS ALSO MORE IN STEP WITH LATEST HPC PROGS. BETTER CHANCES OF RAIN THROUGH TUE ARE JUST TO THE WEST INTO THE WEST HALF OF CWA. STILL...SLIGHTLY BETTER PCPN CHANCES WILL EVEN MAKE IT INTO EAST CWA BY TUE NIGHT. ALL RAIN SHOULD BE DONE BY 12Z WED. THEN ...MORE DRY WEATHER RIGHT INTO THE END OF NEXT WEEK AS A LARGE HIGH BUILDS ACROSS THE REGION THU/FRI. GUIDANCE/HPC HIGHS LOOKED FINE AFTER THE FROPA BUT DID LOWER AFTN DEWPOINTS AND OVERNIGHT LOWS WITH THE EXPECTED DRY AIRMASS. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... PLAN ON VFR CONDITIONS THIS FCST PD WITH SOMEWHAT DRIER AIR TO THE WNW AS SHOWN ON RECENT TAMDAR SDNG FM DLH STREAMING INTO THE FA. SHRTWV APRCHG FM THE SW LATE TNGT/SAT IN MORE SW FLOW ALF WL CAUSE QUITE A BIT OF SC...BUT EXPECT NO PCPN OR CIGS LESS THAN 3000 FT ATTM WITH RELATIVELY DRY LLVLS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT FAIRLY LIGHT WINDS OVER LAKE SUPERIOR THROUGH SUN MORNING (REALLY NOTHING OVER 20KT). WINDS WILL STRENGTHEN LATER SUN THROUGH MON NIGHT AS PRES GRADIENT TIGHTENS BETWEEN HIGH PRES OVER NEW ENGLAND AND A COLD FRONT APPROACHING FROM THE NORTHERN PLAINS. SHOULD SEE SOUTHERLY 15-25KT WINDS DEVELOP OVER THE E HALF OF LAKE SUPERIOR SUN EVENING AND PERSIST THROUGH MON NIGHT. WINDS WILL BE LIGHTER OVER THE W HALF OF THE LAKE AS THEY COMMONLY ARE IN A SOUTHERLY FLOW. THE COLD FRONT IS EXPECTED TO CROSS THE LAKE LATE TUE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ SYNOPSIS/SHORT TERM/MARINE...VOSS LONG TERM...JLA AVIATION...KC mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 128 PM EDT FRI AUG 24 2007 UPDATED FOR AVIATION DISCUSSION .UPDATE... SENT OUT A QUICK UPDATE TO INCLUDE ISOLATED SHOWERS THIS AFTERNOON FOR MNM COUNTY. SHOWERS OVER CENTRAL WI HAVE MADE THEIR WAY INTO SRN MNM COUNTY...PER RADAR LOOP. 800-600 MB FGEN FORCING FROM 12Z RUC SUGGESTS ISOLATED SHRA COULD CONTINUE INTO THE EARLY AFTERNOON HOURS OVER MNM COUNTY. REST OF FCST LOOKS GOOD. && .DISCUSSION (ISSUED AT 417 AM EDT)... ALL IN ALL THE GOING FCST LOOKS PRETTY GOOD. DEBATED ON WHETHER OR NOT TO INCLUDE POPS FOR TODAY. GIVEN CURRENT LOCATION OF PRECIP. OVER SOUTHERN IOWA/NORTHERN ILLINOIS...DRY AIR FILTERING INTO FCST AREA FROM THE NW AND VEERING WINDS TO A MORE ZONAL PATTERN...OPTED TO LEAVE WX GRIDS FOR TODAY AS IS...DRY. GFS CONTINUES TO TRY AND GIVE THE SOUTHEASTERN PORTION OF CWA A BIT OF RAIN...BUT GIVEN CURRENT TRENDS THIS IS A HARD SELL. ON SAT 400MB TROUGH CURRENTLY NOTED OVER UTAH AND COLORADO PASSES THROUGH MIDDAY...HOWEVER WITH WEAK RIDGING AT THE SURFACE AND ZONAL FLOW...MOISTURE STAYS WELL SOUTH KEEPING FA DRY FOR SAT. DID TWEAK A FEW OF THE TEMP GRIDS. SATURDAY NIGHT LOOKS TO BE A COOL NIGHT AS PWAT MIN ALONG WITH CLEARING SKIES SHOULD ALLOW FOR LOW TO MID 40S...WHICH IS IN LINE WITH COOP GUIDANCE. WARMING TREND LOOKS TO STILL BE A GOOD BET FOR EARLY NEXT WEEK. RETURN FLOW BEHIND THIS WEEKENDS HIGH PRESSURE LOOKS TO USHER IN WARMER TEMPS FOR MONDAY. LOWERED HIGH TEMPS ACROSS THE EAST HALF ON MONDAY AS WARMER 850 TEMPS LOOK TO BE ACROSS THE TYPICALLY WARMER WEST HALF OF THE CWA. THE GFS AND ECMWF OFFER DIFFERENT FRONTAL TIMING FOR THE TUES/WED PRECIP CHANCES. WITH THE LATTER BRINGING THE FRONT THROUGH TUESDAY EVENING AND THE FORMER BRINGS THE FRONT THROUGH THE CWA BY 18Z TUES. THIS TIME FRAME WILL BE THE BEST CHANCE FOR PRECIPITATION FOR AWHILE. ON A CLIMATE NOTE...SO FAR THE AUGUST PRECIP. TOTAL IS 0.22 FOR THE NWS OFFICE. THIS VALUE IS FLIRTING WITH THE MINIMUM RECORD FOR OUR SITE. CURRENT MIN AUGUST PRECIP. TOTAL IS 0.56 WHICH OCCURRED IN 1970. WITH HIGH PRESSURE BUILDING IN BY THE END OF NEXT WEEK THIS MID WEEK SYSTEM LOOKS TO BE OUR BEST SHOT. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... DRIER AIR ADVANCING FROM THE NW SHOULD ENSURE VFR CONDITIONS AT BOTH TAF SITES THROUGH MUCH OF THE FCST PERIOD. THE ONLY UNCERTAINTY IS WHETHER SOME OF THE STRATOCUMULUS CLOUDS NW OF THE LAKE MAY WORK INTO KCMX THIS AFTERNOON. INCLUDED A TEMPO GROUP FOR THIS POSSIBILITY. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... FAIRLY LIGHT WINDS WILL DOMINATE LAKE SUPERIOR THROUGH SUN MORNING (REALLY NOTHING OVER 15KT). WINDS WILL RAMP UP LATER SUN THROUGH MON AS PRES GRADIENT TIGHTENS BETWEEN HIGH PRES OVER NEW ENGLAND AND A COLD FRONT APPROACHING FROM THE NORTHERN PLAINS. SHOULD SEE SOUTHERLY 15-25KT WINDS DEVELOP OVER THE E HALF OF LAKE SUPERIOR SUN EVENING AND PERSIST THROUGH MON NIGHT. WINDS WILL BE LIGHTER OVER THE W PORTION OF THE LAKE AS THEY TYPICALLY ARE IN SOUTHERLY WIND REGIMES. THERE IS UNCERTAINTY IN EXACTLY WHEN THE COLD FRONT WILL PASS...AND WOULD EXPECT SOME CHANGES TO TIMING ITS PASSAGE IN LATER FORECASTS. FOR NOW...COLD FRONT IS EXPECTED TO CROSS THE LAKE LATE TUE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ UPDATE...VOSS DISCUSSION...PEARSON AVIATION...VOSS MARINE...ROLFSON mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 1203 PM EDT FRI AUG 24 2007 .UPDATE... SENT OUT A QUICK UPDATE TO INCLUDE ISOLATED SHOWERS THIS AFTERNOON FOR MNM COUNTY. SHOWERS OVER CENTRAL WI HAVE MADE THEIR WAY INTO SRN MNM COUNTY...PER RADAR LOOP. 800-600 MB FGEN FORCING FROM 12Z RUC SUGGESTS ISOLATED SHRA COULD CONTINUE INTO THE EARLY AFTERNOON HOURS OVER MNM COUNTY. REST OF FCST LOOKS GOOD. && .DISCUSSION (ISSUED AT 417 AM EDT)... ALL IN ALL THE GOING FCST LOOKS PRETTY GOOD. DEBATED ON WHETHER OR NOT TO INCLUDE POPS FOR TODAY. GIVEN CURRENT LOCATION OF PRECIP. OVER SOUTHERN IOWA/NORTHERN ILLINOIS...DRY AIR FILTERING INTO FCST AREA FROM THE NW AND VEERING WINDS TO A MORE ZONAL PATTERN...OPTED TO LEAVE WX GRIDS FOR TODAY AS IS...DRY. GFS CONTINUES TO TRY AND GIVE THE SOUTHEASTERN PORTION OF CWA A BIT OF RAIN...BUT GIVEN CURRENT TRENDS THIS IS A HARD SELL. ON SAT 400MB TROUGH CURRENTLY NOTED OVER UTAH AND COLORADO PASSES THROUGH MIDDAY...HOWEVER WITH WEAK RIDGING AT THE SURFACE AND ZONAL FLOW...MOISTURE STAYS WELL SOUTH KEEPING FA DRY FOR SAT. DID TWEAK A FEW OF THE TEMP GRIDS. SATURDAY NIGHT LOOKS TO BE A COOL NIGHT AS PWAT MIN ALONG WITH CLEARING SKIES SHOULD ALLOW FOR LOW TO MID 40S...WHICH IS IN LINE WITH COOP GUIDANCE. WARMING TREND LOOKS TO STILL BE A GOOD BET FOR EARLY NEXT WEEK. RETURN FLOW BEHIND THIS WEEKENDS HIGH PRESSURE LOOKS TO USHER IN WARMER TEMPS FOR MONDAY. LOWERED HIGH TEMPS ACROSS THE EAST HALF ON MONDAY AS WARMER 850 TEMPS LOOK TO BE ACROSS THE TYPICALLY WARMER WEST HALF OF THE CWA. THE GFS AND ECMWF OFFER DIFFERENT FRONTAL TIMING FOR THE TUES/WED PRECIP CHANCES. WITH THE LATTER BRINGING THE FRONT THROUGH TUESDAY EVENING AND THE FORMER BRINGS THE FRONT THROUGH THE CWA BY 18Z TUES. THIS TIME FRAME WILL BE THE BEST CHANCE FOR PRECIPITATION FOR AWHILE. ON A CLIMATE NOTE...SO FAR THE AUGUST PRECIP. TOTAL IS 0.22 FOR THE NWS OFFICE. THIS VALUE IS FLIRTING WITH THE MINIMUM RECORD FOR OUR SITE. CURRENT MIN AUGUST PRECIP. TOTAL IS 0.56 WHICH OCCURRED IN 1970. WITH HIGH PRESSURE BUILDING IN BY THE END OF NEXT WEEK THIS MID WEEK SYSTEM LOOKS TO BE OUR BEST SHOT. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... DRIER AIR HAS BEEN MOVING INTO THE AREA DURING THE NIGHT...AND THIS WILL ENSURE VFR CONDITIONS THIS MORNING AT KCMX/KSAW. IN FACT...VFR CONDITIONS WILL PREVAIL FOR THE ENTIRE FCST PERIOD AT BOTH SITES. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... FAIRLY LIGHT WINDS WILL DOMINATE LAKE SUPERIOR THROUGH SUN MORNING (REALLY NOTHING OVER 15KT). WINDS WILL RAMP UP LATER SUN THROUGH MON AS PRES GRADIENT TIGHTENS BETWEEN HIGH PRES OVER NEW ENGLAND AND A COLD FRONT APPROACHING FROM THE NORTHERN PLAINS. SHOULD SEE SOUTHERLY 15-25KT WINDS DEVELOP OVER THE E HALF OF LAKE SUPERIOR SUN EVENING AND PERSIST THROUGH MON NIGHT. WINDS WILL BE LIGHTER OVER THE W PORTION OF THE LAKE AS THEY TYPICALLY ARE IN SOUTHERLY WIND REGIMES. THERE IS UNCERTAINTY IN EXACTLY WHEN THE COLD FRONT WILL PASS...AND WOULD EXPECT SOME CHANGES TO TIMING ITS PASSAGE IN LATER FORECASTS. FOR NOW...COLD FRONT IS EXPECTED TO CROSS THE LAKE LATE TUE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ UPDATE...VOSS DISCUSSION...PEARSON AVIATION/MARINE...ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 135 AM EDT FRI AUG 24 2007 UPDATED AVIATION SECTION FOR 06Z TAF ISSUANCE .UPDATE (ISSUED 921 PM EDT THU AUG 23)... SCATTERED SHOWERS OVER THE EASTERN PORTIONS OF THE CWA CONTINUE THIS EVENING...SUPPORTED BY UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A 110 KT JET BETWEEN WAWA ONTARIO AND JAMES BAY. AS THIS UPPER JET CONTINUES OFF TO THE NE...SHOWERS WILL EXIT THE CWA. LINEAR EXTRAPOLATION SUPPORTS AN ENDING TIMING ABOUT AN HOUR OR TWO FASTER THAN THE PREVIOUS FORECAST...AND HAVE ADJUSTED THE GRIDS TO ACCOUNT FOR THE SPEED. REGARDING AMOUNTS...SOME LOCATIONS IN THE SOUTH CENTRAL U.P. MANAGED TO PICK UP BETWEEN A 0.50 INCH AND AN INCH OF RAIN...WITH RADAR ESTIMATES EVEN SUGGESTING A LITTLE HIGHER. SEE THE LATEST ARBRTPMQT FOR A FULL LIST OF AMOUNTS. FOR THE REST OF THE NIGHT...MAIN CHANGE WAS TO RAISE TEMPS A FEW DEGREES GIVEN EXTENSIVE CLOUD COVER. IN ADDITION...REMOVED THE FOG OFF THE WEST HALF OF LAKE SUPERIOR GIVEN LOWER DEWPOINTS AND IN GENERAL DRY LOW LEVEL AIR ADVECTING EASTWARD FROM NORTHERN MN (SEE INL SOUNDING). HIGHER DEWPOINTS IN THE EASTERN U.P./EASTERN LAKE SUPERIOR AND COOLER TEMPERATURES SUPPORT KEEPING THE PATCHY FOG MENTION THERE. && .SHORT TERM (TONIGHT AND FRI ISSUED AT 415 PM EDT THU AUG 23)... MAIN CONCERNS FOCUS ON PCPN CHCS TONIGHT AND PATCHY FOG POTENTIAL. STRONG ORGANIZED CONVECTION AND BOW ECHO STRUCTURE LOOKS LIKE IT WILL STAY WELL SOUTH THIS EVENING OVER SRN WI/NRN IL. A SECONDARY AREA OF LIGHT -SHRA FARTHER NORTH OVER MN AND NW WI HAS MOVED INTO WRN UPR MI IN THE PAST HR OR TWO. THESE SHOWERS ARE SUPPORTED BY A SHORTWAVE MOVING THROUGH NRN MN AND WEAK UPR DIV IN RRQ OF 100+ KT 3H IN VICINITY OF JAMES BAY. WEAK INSTABILITY OF A COUPLE HUNDRED J/KG AND ABSENCE OF STEEP MID-LVL LAPSE RATES HAVE RESULTED IN NO LIGHTNING STRIKES WITH ANY OF THESE SHRA. FOLLOWING LATEST RUC AND NAM MODEL TRENDS ALONG WITH UPSTREAM RADAR TRENDS HAVE DECIDED TO INCLUDE SCATTERED SHOWERS IN FOR THE WEST HALF OF THE CWFA THIS EVENING. GENERALLY EXPECT LIGHT PCPN AMOUNTS OF A TENTH OF AN INCH OR LESS FROM SHRA. ALSO INCLUDED ISOLD SHRA FOR THE ERN HALF OF THE FCST AREA FOR LATE EVENING HOURS ALTHOUGH DRIER WEDGE OF AIR FROM 850-700 MB AS NOTED ON LATEST TAMDAR SNDGS MAY HELP DISSIPATE SHOWERS AS THEY MOVE EAST THIS EVENING. LOSS OF UPR DIV BY LATE EVENING WILL ALSO WORK TO DISSIPATE SHOWERS BY THE OVERNIGHT HRS. KEPT IN PATCHY FOG OVER ERN HALF COUNTIES TONIGHT AS DEWPOINT DEPRESSION REMAIN LESS THAN 5F OVER MANY LOCATIONS AND ONSHORE SRLY FLOW WILL PERSIST OFF LAKE MI THROUGH THE EVENING HRS. FOR FRIDAY...MODEL CONSENSUS SUGGESTS ANY MCS/S THAT FORM IN WSW FLOW ALOFT SHOULD REMAIN WELL SOUTH OF THE FCST AREA. THE ONLY MODEL EXCEPTION IS THE GFS WHICH HAS A HUGE BLOB OF CONVECTIVE PCPN MOVING INTO SCNTRL AND ERN UPR MI IN THE AFTERNOON. GFS LOOKS SUSPICIOUSLY CONTAMINATED BY CONVECTIVE FEEDBACK THOUGH SO HAVE IGNORED THIS SOLN AND DECIDED TO GO WITH A DRY FCST FOR THE ENTIRE CWA. EXPECT DRIER AIR TO GRADUALLY WORK FROM NW BEHIND COLD FRONT WHICH PASSES AREA TONIGHT. DRIER AIR SHOULD GRADUALLY BREAK UP CLOUDS OVER THE WRN HALF OF FCST AREA BY LATE MORNING/EARLY AFTERNOON. DECIDED TO GO SLIGHTLY ABV MODEL GUIDANCE TEMPS AS EXPECT A BIT MORE MIXING AND SUNSHINE TO ALLOW FOR 11-13C TEMPS TO MIX TO SFC. EXPECT INLAND READINGS IN THE LOW TO MID 70S FOR MOST LOCATIONS. .LONG TERM (FRI NIGHT THROUGH NEXT THU)... ACTIVE FRONTAL BOUNDARY SHOULD BE WELL EAST OF CWA FRI NIGHT. FAR EAST ZONES DO STAY ON EDGE OF HIGHER MID LEVEL MOISTURE AND H85-H7 FRONTOGENESIS BUT CONSIDERING MODELS LATELY ARE VERIFYING TOO FAR NORTH WITH QPF...AND SINCE SFC BOUNDARY AND BETTER LOW LEVEL MOISTURE INFLOW REMAINS TO THE EAST...EXPECT ONLY MID LEVEL CLOUDS. HIGH PRESSURE BUILDS IN LATE FRI NIGHT AND CONTINUES THROUGH SAT NIGHT. BY LATE SUN...H85 WINDS BEGIN TO BACK TO THE WEST AND SOUTHWEST WHICH BRINGS IN MUCH WARMER AIR AT H85. SOUNDINGS INDICATE NOT MUCH MOISTURE AVAILABLE...SO DESPITE GFS INDICATING LIGHT QPF...KEPT GRIDS DRY SUN NIGHT IN THE WARM AIR ADVECTION REGIME. NOT OUT OF THE QUESTION TO HAVE A FEW SPRINKLES OUT OF THE THICKENING MID CLOUD. PRIMARY FOCUS FOR PCPN ON MON SHOULD BE TO THE NW OF LK SUPERIOR ON NOSE OF H85 JET/MAXIMUM H85 THETA-E AND CLOSER TO SHORTWAVE TRACKING ACROSS SOUTHERN MANITOBA INTO NW ONTARIO. CUT POPS ON MON EXCEPT FOR ISLE ROYALE. SFC FRONT MOVES INTO MN LATE MON. GFS INDICATES SW WINDS FM H95-H85 NEARING 30KT. H85 TEMPS ALSO ON THE RISE...TO NEAR +19C BY LATE DAY IN THE WEST. POTENTIAL IS THERE FOR A WARM AND BREEZY MON WITH TEMPS REACHING WELL INTO THE 80S. DESPITE THE WARM TEMPS...DEWPOINTS REMAIN IN THE 50S WHICH COULD RESULT IN LOW RH VALUES AND MAKE FIRE WEATHER BIGGER CONCERN. ECMWF/GFS/NCEP ENSEMBLE MEAN INDICATE GENERAL ZONAL FLOW STAYS IN PLACE NEXT WEEK. THERE ARE TIMES WHEN THE FLOW BUCKLES SOME AS MORE TROFFINESS MOVES ACROSS THE REGION. SFC FRONT OVR MN ON MON PROJECTED THROUGH UPR MI ON TUE AS A MORE SIGNIFICANT SHORTWAVE CROSSES MANITOBA AND NORTHWEST ONTARIO. OTHER THAN THE WARM UP ON MON AHEAD OF THE FRONT...NEAR NORMAL TEMPS ARE EXPECTED THROUGH THE REST OF DAYS 4-7. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... MAIN CONCERN CONTINUES TO BE FOG FOR THE OVERNIGHT HOURS. DRY AIR FILTERING INTO THE WESTERN U.P. AND PLENTY OF MID CLOUDS KEEPING TEMPERATURES UP HAS PREVENTED FOG DEVELOPMENT AT CMX. HOWEVER...THIS DRY AIR HAS BEEN SLOWER TO ARRIVE AT SAW...PARTICULARLY DUE TO THE WIND DIRECTION CURRENTLY AT NNE. THESE WINDS ARE UPSLOPING INTO SAW...AND COMBINED WITH THE LITTLE RAIN THAT MOVED ACROSS LAST EVENING...LIFR CIGS WITH MVFR VSBY HAVE DEVELOPED. HOWEVER...IN THE LAST HR...LIFR CIGS HAVE DISSIPATED. IT LOOKS LIKE WINDS SHOULD TURN TO THE NW BETWEEN 08 AND 09Z...WHICH SHOULD BOTH END THE UPSLOPE AND BRING DRIER AIR IN. THUS HAVE DISSIPATED THE FOG AROUND 09Z FOR THE SAW TAF. BEYOND 09Z...VFR CONDITIONS ARE EXPECTED AT BOTH TAF SITES AS DRY AIR CONTINUES TO PUSH IN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... FRONT WILL MOVE ACROSS THE LAKE TONIGHT. EXPECT PATCHY FOG TO LINGER OVER THE EAST HALF OF THE LAKE THROUGH FRI MORNING BEFORE DISSIPATING WITH DRIER AIR IN WAKE OF COLD FRONT. WINDS WILL GENERALLY REMAIN 20 KT OR LESS THROUGH THE WEEKEND. WINDS MAY APPROACH 25 KT OVER THE ERN HALF OF THE LAKE MON INTO TUE IN ADVANCE OF AN APPROACHING COLD FRONT FROM THE NORTHERN PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...AJ SHORT TERM...VOSS LONG TERM...JLA AVIATION...AJ MARINE...VOSS/AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 921 PM EDT THU AUG 23 2007 .UPDATE... SCATTERED SHOWERS OVER THE EASTERN PORTIONS OF THE CWA CONTINUE THIS EVENING...SUPPORTED BY UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A 110 KT JET BETWEEN WAWA ONTARIO AND JAMES BAY. AS THIS UPPER JET CONTINUES OFF TO THE NE...SHOWERS WILL EXIT THE CWA. LINEAR EXTRAPOLATION SUPPORTS AN ENDING TIMING ABOUT AN HOUR OR TWO FASTER THAN THE PREVIOUS FORECAST...AND HAVE ADJUSTED THE GRIDS TO ACCOUNT FOR THE SPEED. REGARDING AMOUNTS...SOME LOCATIONS IN THE SOUTH CENTRAL U.P. MANAGED TO PICK UP BETWEEN A 0.50 INCH AND AN INCH OF RAIN...WITH RADAR ESTIMATES EVEN SUGGESTING A LITTLE HIGHER. SEE THE LATEST ARBRTPMQT FOR A FULL LIST OF AMOUNTS. FOR THE REST OF THE NIGHT...MAIN CHANGE WAS TO RAISE TEMPS A FEW DEGREES GIVEN EXTENSIVE CLOUD COVER. IN ADDITION...REMOVED THE FOG OFF THE WEST HALF OF LAKE SUPERIOR GIVEN LOWER DEWPOINTS AND IN GENERAL DRY LOW LEVEL AIR ADVECTING EASTWARD FROM NORTHERN MN (SEE INL SOUNDING). HIGHER DEWPOINTS IN THE EASTERN U.P./EASTERN LAKE SUPERIOR AND COOLER TEMPERATURES SUPPORT KEEPING THE PATCHY FOG MENTION THERE. && .SHORT TERM (TONIGHT AND FRI)... MAIN CONCERNS FOCUS ON PCPN CHCS TONIGHT AND PATCHY FOG POTENTIAL. STRONG ORGANIZED CONVECTION AND BOW ECHO STRUCTURE LOOKS LIKE IT WILL STAY WELL SOUTH THIS EVENING OVER SRN WI/NRN IL. A SECONDARY AREA OF LIGHT -SHRA FARTHER NORTH OVER MN AND NW WI HAS MOVED INTO WRN UPR MI IN THE PAST HR OR TWO. THESE SHOWERS ARE SUPPORTED BY A SHORTWAVE MOVING THROUGH NRN MN AND WEAK UPR DIV IN RRQ OF 100+ KT 3H IN VICINITY OF JAMES BAY. WEAK INSTABILITY OF A COUPLE HUNDRED J/KG AND ABSENCE OF STEEP MID-LVL LAPSE RATES HAVE RESULTED IN NO LIGHTNING STRIKES WITH ANY OF THESE SHRA. FOLLOWING LATEST RUC AND NAM MODEL TRENDS ALONG WITH UPSTREAM RADAR TRENDS HAVE DECIDED TO INCLUDE SCATTERED SHOWERS IN FOR THE WEST HALF OF THE CWFA THIS EVENING. GENERALLY EXPECT LIGHT PCPN AMOUNTS OF A TENTH OF AN INCH OR LESS FROM SHRA. ALSO INCLUDED ISOLD SHRA FOR THE ERN HALF OF THE FCST AREA FOR LATE EVENING HOURS ALTHOUGH DRIER WEDGE OF AIR FROM 850-700 MB AS NOTED ON LATEST TAMDAR SNDGS MAY HELP DISSIPATE SHOWERS AS THEY MOVE EAST THIS EVENING. LOSS OF UPR DIV BY LATE EVENING WILL ALSO WORK TO DISSIPATE SHOWERS BY THE OVERNIGHT HRS. KEPT IN PATCHY FOG OVER ERN HALF COUNTIES TONIGHT AS DEWPOINT DEPRESSION REMAIN LESS THAN 5F OVER MANY LOCATIONS AND ONSHORE SRLY FLOW WILL PERSIST OFF LAKE MI THROUGH THE EVENING HRS. FOR FRIDAY...MODEL CONSENSUS SUGGESTS ANY MCS/S THAT FORM IN WSW FLOW ALOFT SHOULD REMAIN WELL SOUTH OF THE FCST AREA. THE ONLY MODEL EXCEPTION IS THE GFS WHICH HAS A HUGE BLOB OF CONVECTIVE PCPN MOVING INTO SCNTRL AND ERN UPR MI IN THE AFTERNOON. GFS LOOKS SUSPICIOUSLY CONTAMINATED BY CONVECTIVE FEEDBACK THOUGH SO HAVE IGNORED THIS SOLN AND DECIDED TO GO WITH A DRY FCST FOR THE ENTIRE CWA. EXPECT DRIER AIR TO GRADUALLY WORK FROM NW BEHIND COLD FRONT WHICH PASSES AREA TONIGHT. DRIER AIR SHOULD GRADUALLY BREAK UP CLOUDS OVER THE WRN HALF OF FCST AREA BY LATE MORNING/EARLY AFTERNOON. DECIDED TO GO SLIGHTLY ABV MODEL GUIDANCE TEMPS AS EXPECT A BIT MORE MIXING AND SUNSHINE TO ALLOW FOR 11-13C TEMPS TO MIX TO SFC. EXPECT INLAND READINGS IN THE LOW TO MID 70S FOR MOST LOCATIONS. .LONG TERM (FRI NIGHT THROUGH NEXT THU)... ACTIVE FRONTAL BOUNDARY SHOULD BE WELL EAST OF CWA FRI NIGHT. FAR EAST ZONES DO STAY ON EDGE OF HIGHER MID LEVEL MOISTURE AND H85-H7 FRONTOGENESIS BUT CONSIDERING MODELS LATELY ARE VERIFYING TOO FAR NORTH WITH QPF...AND SINCE SFC BOUNDARY AND BETTER LOW LEVEL MOISTURE INFLOW REMAINS TO THE EAST...EXPECT ONLY MID LEVEL CLOUDS. HIGH PRESSURE BUILDS IN LATE FRI NIGHT AND CONTINUES THROUGH SAT NIGHT. BY LATE SUN...H85 WINDS BEGIN TO BACK TO THE WEST AND SOUTHWEST WHICH BRINGS IN MUCH WARMER AIR AT H85. SOUNDINGS INDICATE NOT MUCH MOISTURE AVAILABLE...SO DESPITE GFS INDICATING LIGHT QPF...KEPT GRIDS DRY SUN NIGHT IN THE WARM AIR ADVECTION REGIME. NOT OUT OF THE QUESTION TO HAVE A FEW SPRINKLES OUT OF THE THICKENING MID CLOUD. PRIMARY FOCUS FOR PCPN ON MON SHOULD BE TO THE NW OF LK SUPERIOR ON NOSE OF H85 JET/MAXIMUM H85 THETA-E AND CLOSER TO SHORTWAVE TRACKING ACROSS SOUTHERN MANITOBA INTO NW ONTARIO. CUT POPS ON MON EXCEPT FOR ISLE ROYALE. SFC FRONT MOVES INTO MN LATE MON. GFS INDICATES SW WINDS FM H95-H85 NEARING 30KT. H85 TEMPS ALSO ON THE RISE...TO NEAR +19C BY LATE DAY IN THE WEST. POTENTIAL IS THERE FOR A WARM AND BREEZY MON WITH TEMPS REACHING WELL INTO THE 80S. DESPITE THE WARM TEMPS...DEWPOINTS REMAIN IN THE 50S WHICH COULD RESULT IN LOW RH VALUES AND MAKE FIRE WEATHER BIGGER CONCERN. ECMWF/GFS/NCEP ENSEMBLE MEAN INDICATE GENERAL ZONAL FLOW STAYS IN PLACE NEXT WEEK. THERE ARE TIMES WHEN THE FLOW BUCKLES SOME AS MORE TROFFINESS MOVES ACROSS THE REGION. SFC FRONT OVR MN ON MON PROJECTED THROUGH UPR MI ON TUE AS A MORE SIGNIFICANT SHORTWAVE CROSSES MANITOBA AND NORTHWEST ONTARIO. OTHER THAN THE WARM UP ON MON AHEAD OF THE FRONT...NEAR NORMAL TEMPS ARE EXPECTED THROUGH THE REST OF DAYS 4-7. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... OUTSIDE OF A FEW -SHRA MOVING ACROSS THE TAF SITES VERY EARLY IN THE PERIOD WITH VISIBILITIES DROPPING TO MVFR...EXPECTING VFR CONDITIONS THROUGH THE PERIOD. PREVIOUS FORECAST HAD MENTION OF LOW MVFR CEILINGS ALONG WITH TEMPO GROUPS FOR SOME FOG. AM UNSURE NOW IF THAT WILL OCCUR WITH LOWER DEWPOINTS HEADING E FROM NORTHERN MN...WHILE AN OVERCAST MID-CLOUD DECK PREVAILS THROUGH THE NIGHT KEEPING TEMPERATURES UP. IN ADDITION...THESE LOWER DEWPOINTS SHOULD RID ANY FOG THAT MIGHT BE ON LAKE SUPERIOR...REDUCING THE CHANCE OF UPSLOPE FOG INTO CMX. THUS HAVE REMOVED THE LOWER CEILINGS AND TEMPO GROUPS FROM THE TAFS FOR NOW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... FRONT WILL MOVE ACROSS THE LAKE TONIGHT. EXPECT PATCHY FOG TO LINGER OVER THE LAKE TONIGHT AND OVER THE ERN HALF OF THE LAKE FRI BEFORE DISSIPATING WITH DRIER AIR IN WAKE OF COLD FRONT. WINDS WILL GENERALLY REMAIN 20 KT OR LESS THROUGH THE WEEKEND. WINDS MAY APPROACH 25 KT OVER THE ERN HALF OF THE LAKE MON INTO TUE IN ADVANCE OF AN APPROACHING COLD FRONT FROM THE NORTHERN PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...AJ SHORT TERM...VOSS LONG TERM...JLA AVIATION...AJ MARINE...VOSS mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 726 PM EDT THU AUG 23 2007 UPDATED AVIATION SECTION FOR 00Z TAF ISSUANCE .SHORT TERM (TONIGHT AND FRI)... MAIN CONCERNS FOCUS ON PCPN CHCS TONIGHT AND PATCHY FOG POTENTIAL. STRONG ORGANIZED CONVECTION AND BOW ECHO STRUCTURE LOOKS LIKE IT WILL STAY WELL SOUTH THIS EVENING OVER SRN WI/NRN IL. A SECONDARY AREA OF LIGHT -SHRA FARTHER NORTH OVER MN AND NW WI HAS MOVED INTO WRN UPR MI IN THE PAST HR OR TWO. THESE SHOWERS ARE SUPPORTED BY A SHORTWAVE MOVING THROUGH NRN MN AND WEAK UPR DIV IN RRQ OF 100+ KT 3H IN VICINITY OF JAMES BAY. WEAK INSTABILITY OF A COUPLE HUNDRED J/KG AND ABSENCE OF STEEP MID-LVL LAPSE RATES HAVE RESULTED IN NO LIGHTNING STRIKES WITH ANY OF THESE SHRA. FOLLOWING LATEST RUC AND NAM MODEL TRENDS ALONG WITH UPSTREAM RADAR TRENDS HAVE DECIDED TO INCLUDE SCATTERED SHOWERS IN FOR THE WEST HALF OF THE CWFA THIS EVENING. GENERALLY EXPECT LIGHT PCPN AMOUNTS OF A TENTH OF AN INCH OR LESS FROM SHRA. ALSO INCLUDED ISOLD SHRA FOR THE ERN HALF OF THE FCST AREA FOR LATE EVENING HOURS ALTHOUGH DRIER WEDGE OF AIR FROM 850-700 MB AS NOTED ON LATEST TAMDAR SNDGS MAY HELP DISSIPATE SHOWERS AS THEY MOVE EAST THIS EVENING. LOSS OF UPR DIV BY LATE EVENING WILL ALSO WORK TO DISSIPATE SHOWERS BY THE OVERNIGHT HRS. KEPT IN PATCHY FOG OVER ERN HALF COUNTIES TONIGHT AS DEWPOINT DEPRESSION REMAIN LESS THAN 5F OVER MANY LOCATIONS AND ONSHORE SRLY FLOW WILL PERSIST OFF LAKE MI THROUGH THE EVENING HRS. FOR FRIDAY...MODEL CONSENSUS SUGGESTS ANY MCS/S THAT FORM IN WSW FLOW ALOFT SHOULD REMAIN WELL SOUTH OF THE FCST AREA. THE ONLY MODEL EXCEPTION IS THE GFS WHICH HAS A HUGE BLOB OF CONVECTIVE PCPN MOVING INTO SCNTRL AND ERN UPR MI IN THE AFTERNOON. GFS LOOKS SUSPICIOUSLY CONTAMINATED BY CONVECTIVE FEEDBACK THOUGH SO HAVE IGNORED THIS SOLN AND DECIDED TO GO WITH A DRY FCST FOR THE ENTIRE CWA. EXPECT DRIER AIR TO GRADUALLY WORK FROM NW BEHIND COLD FRONT WHICH PASSES AREA TONIGHT. DRIER AIR SHOULD GRADUALLY BREAK UP CLOUDS OVER THE WRN HALF OF FCST AREA BY LATE MORNING/EARLY AFTERNOON. DECIDED TO GO SLIGHTLY ABV MODEL GUIDANCE TEMPS AS EXPECT A BIT MORE MIXING AND SUNSHINE TO ALLOW FOR 11-13C TEMPS TO MIX TO SFC. EXPECT INLAND READINGS IN THE LOW TO MID 70S FOR MOST LOCATIONS. .LONG TERM (FRI NIGHT THROUGH NEXT THU)... ACTIVE FRONTAL BOUNDARY SHOULD BE WELL EAST OF CWA FRI NIGHT. FAR EAST ZONES DO STAY ON EDGE OF HIGHER MID LEVEL MOISTURE AND H85-H7 FRONTOGENESIS BUT CONSIDERING MODELS LATELY ARE VERIFYING TOO FAR NORTH WITH QPF...AND SINCE SFC BOUNDARY AND BETTER LOW LEVEL MOISTURE INFLOW REMAINS TO THE EAST...EXPECT ONLY MID LEVEL CLOUDS. HIGH PRESSURE BUILDS IN LATE FRI NIGHT AND CONTINUES THROUGH SAT NIGHT. BY LATE SUN...H85 WINDS BEGIN TO BACK TO THE WEST AND SOUTHWEST WHICH BRINGS IN MUCH WARMER AIR AT H85. SOUNDINGS INDICATE NOT MUCH MOISTURE AVAILABLE...SO DESPITE GFS INDICATING LIGHT QPF...KEPT GRIDS DRY SUN NIGHT IN THE WARM AIR ADVECTION REGIME. NOT OUT OF THE QUESTION TO HAVE A FEW SPRINKLES OUT OF THE THICKENING MID CLOUD. PRIMARY FOCUS FOR PCPN ON MON SHOULD BE TO THE NW OF LK SUPERIOR ON NOSE OF H85 JET/MAXIMUM H85 THETA-E AND CLOSER TO SHORTWAVE TRACKING ACROSS SOUTHERN MANITOBA INTO NW ONTARIO. CUT POPS ON MON EXCEPT FOR ISLE ROYALE. SFC FRONT MOVES INTO MN LATE MON. GFS INDICATES SW WINDS FM H95-H85 NEARING 30KT. H85 TEMPS ALSO ON THE RISE...TO NEAR +19C BY LATE DAY IN THE WEST. POTENTIAL IS THERE FOR A WARM AND BREEZY MON WITH TEMPS REACHING WELL INTO THE 80S. DESPITE THE WARM TEMPS...DEWPOINTS REMAIN IN THE 50S WHICH COULD RESULT IN LOW RH VALUES AND MAKE FIRE WEATHER BIGGER CONCERN. ECMWF/GFS/NCEP ENSEMBLE MEAN INDICATE GENERAL ZONAL FLOW STAYS IN PLACE NEXT WEEK. THERE ARE TIMES WHEN THE FLOW BUCKLES SOME AS MORE TROFFINESS MOVES ACROSS THE REGION. SFC FRONT OVR MN ON MON PROJECTED THROUGH UPR MI ON TUE AS A MORE SIGNIFICANT SHORTWAVE CROSSES MANITOBA AND NORTHWEST ONTARIO. OTHER THAN THE WARM UP ON MON AHEAD OF THE FRONT...NEAR NORMAL TEMPS ARE EXPECTED THROUGH THE REST OF DAYS 4-7. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... OUTSIDE OF A FEW -SHRA MOVING ACROSS THE TAF SITES VERY EARLY IN THE PERIOD WITH VISIBILITIES DROPPING TO MVFR...EXPECTING VFR CONDITIONS THROUGH THE PERIOD. PREVIOUS FORECAST HAD MENTION OF LOW MVFR CEILINGS ALONG WITH TEMPO GROUPS FOR SOME FOG. AM UNSURE NOW IF THAT WILL OCCUR WITH LOWER DEWPOINTS HEADING E FROM NORTHERN MN...WHILE AN OVERCAST MID-CLOUD DECK PREVAILS THROUGH THE NIGHT KEEPING TEMPERATURES UP. IN ADDITION...THESE LOWER DEWPOINTS SHOULD RID ANY FOG THAT MIGHT BE ON LAKE SUPERIOR...REDUCING THE CHANCE OF UPSLOPE FOG INTO CMX. THUS HAVE REMOVED THE LOWER CEILINGS AND TEMPO GROUPS FROM THE TAFS FOR NOW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... FRONT WILL MOVE ACROSS THE LAKE TONIGHT. EXPECT PATCHY FOG TO LINGER OVER THE LAKE TONIGHT AND OVER THE ERN HALF OF THE LAKE FRI BEFORE DISSIPATING WITH DRIER AIR IN WAKE OF COLD FRONT. WINDS WILL GENERALLY REMAIN 20 KT OR LESS THROUGH THE WEEKEND. WINDS MAY APPROACH 25 KT OVER THE ERN HALF OF THE LAKE MON INTO TUE IN ADVANCE OF AN APPROACHING COLD FRONT FROM THE NORTHERN PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...VOSS LONG TERM...JLA AVIATION...AJ MARINE...VOSS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 415 PM EDT THU AUG 23 2007 .SHORT TERM (TONIGHT AND FRI)... MAIN CONCERNS FOCUS ON PCPN CHCS TONIGHT AND PATCHY FOG POTENTIAL. STRONG ORGANIZED CONVECTION AND BOW ECHO STRUCTURE LOOKS LIKE IT WILL STAY WELL SOUTH THIS EVENING OVER SRN WI/NRN IL. A SECONDARY AREA OF LIGHT -SHRA FARTHER NORTH OVER MN AND NW WI HAS MOVED INTO WRN UPR MI IN THE PAST HR OR TWO. THESE SHOWERS ARE SUPPORTED BY A SHORTWAVE MOVING THROUGH NRN MN AND WEAK UPR DIV IN RRQ OF 100+ KT 3H IN VICINITY OF JAMES BAY. WEAK INSTABILITY OF A COUPLE HUNDRED J/KG AND ABSENCE OF STEEP MID-LVL LAPSE RATES HAVE RESULTED IN NO LIGHTNING STRIKES WITH ANY OF THESE SHRA. FOLLOWING LATEST RUC AND NAM MODEL TRENDS ALONG WITH UPSTREAM RADAR TRENDS HAVE DECIDED TO INCLUDE SCATTERED SHOWERS IN FOR THE WEST HALF OF THE CWFA THIS EVENING. GENERALLY EXPECT LIGHT PCPN AMOUNTS OF A TENTH OF AN INCH OR LESS FROM SHRA. ALSO INCLUDED ISOLD SHRA FOR THE ERN HALF OF THE FCST AREA FOR LATE EVENING HOURS ALTHOUGH DRIER WEDGE OF AIR FROM 850-700 MB AS NOTED ON LATEST TAMDAR SNDGS MAY HELP DISSIPATE SHOWERS AS THEY MOVE EAST THIS EVENING. LOSS OF UPR DIV BY LATE EVENING WILL ALSO WORK TO DISSIPATE SHOWERS BY THE OVERNIGHT HRS. KEPT IN PATCHY FOG OVER ERN HALF COUNTIES TONIGHT AS DEWPOINT DEPRESSION REMAIN LESS THAN 5F OVER MANY LOCATIONS AND ONSHORE SRLY FLOW WILL PERSIST OFF LAKE MI THROUGH THE EVENING HRS. FOR FRIDAY...MODEL CONSENSUS SUGGESTS ANY MCS/S THAT FORM IN WSW FLOW ALOFT SHOULD REMAIN WELL SOUTH OF THE FCST AREA. THE ONLY MODEL EXCEPTION IS THE GFS WHICH HAS A HUGE BLOB OF CONVECTIVE PCPN MOVING INTO SCNTRL AND ERN UPR MI IN THE AFTERNOON. GFS LOOKS SUSPICIOUSLY CONTAMINATED BY CONVECTIVE FEEDBACK THOUGH SO HAVE IGNORED THIS SOLN AND DECIDED TO GO WITH A DRY FCST FOR THE ENTIRE CWA. EXPECT DRIER AIR TO GRADUALLY WORK FROM NW BEHIND COLD FRONT WHICH PASSES AREA TONIGHT. DRIER AIR SHOULD GRADUALLY BREAK UP CLOUDS OVER THE WRN HALF OF FCST AREA BY LATE MORNING/EARLY AFTERNOON. DECIDED TO GO SLIGHTLY ABV MODEL GUIDANCE TEMPS AS EXPECT A BIT MORE MIXING AND SUNSHINE TO ALLOW FOR 11-13C TEMPS TO MIX TO SFC. EXPECT INLAND READINGS IN THE LOW TO MID 70S FOR MOST LOCATIONS. .LONG TERM (FRI NIGHT THROUGH NEXT THU)... ACTIVE FRONTAL BOUNDARY SHOULD BE WELL EAST OF CWA FRI NIGHT. FAR EAST ZONES DO STAY ON EDGE OF HIGHER MID LEVEL MOISTURE AND H85-H7 FRONTOGENESIS BUT CONSIDERING MODELS LATELY ARE VERIFYING TOO FAR NORTH WITH QPF...AND SINCE SFC BOUNDARY AND BETTER LOW LEVEL MOISTURE INFLOW REMAINS TO THE EAST...EXPECT ONLY MID LEVEL CLOUDS. HIGH PRESSURE BUILDS IN LATE FRI NIGHT AND CONTINUES THROUGH SAT NIGHT. BY LATE SUN...H85 WINDS BEGIN TO BACK TO THE WEST AND SOUTHWEST WHICH BRINGS IN MUCH WARMER AIR AT H85. SOUNDINGS INDICATE NOT MUCH MOISTURE AVAILABLE...SO DESPITE GFS INDICATING LIGHT QPF...KEPT GRIDS DRY SUN NIGHT IN THE WARM AIR ADVECTION REGIME. NOT OUT OF THE QUESTION TO HAVE A FEW SPRINKLES OUT OF THE THICKENING MID CLOUD. PRIMARY FOCUS FOR PCPN ON MON SHOULD BE TO THE NW OF LK SUPERIOR ON NOSE OF H85 JET/MAXIMUM H85 THETA-E AND CLOSER TO SHORTWAVE TRACKING ACROSS SOUTHERN MANITOBA INTO NW ONTARIO. CUT POPS ON MON EXCEPT FOR ISLE ROYALE. SFC FRONT MOVES INTO MN LATE MON. GFS INDICATES SW WINDS FM H95-H85 NEARING 30KT. H85 TEMPS ALSO ON THE RISE...TO NEAR +19C BY LATE DAY IN THE WEST. POTENTIAL IS THERE FOR A WARM AND BREEZY MON WITH TEMPS REACHING WELL INTO THE 80S. DESPITE THE WARM TEMPS...DEWPOINTS REMAIN IN THE 50S WHICH COULD RESULT IN LOW RH VALUES AND MAKE FIRE WEATHER BIGGER CONCERN. ECMWF/GFS/NCEP ENSEMBLE MEAN INDICATE GENERAL ZONAL FLOW STAYS IN PLACE NEXT WEEK. THERE ARE TIMES WHEN THE FLOW BUCKLES SOME AS MORE TROFFINESS MOVES ACROSS THE REGION. SFC FRONT OVR MN ON MON PROJECTED THROUGH UPR MI ON TUE AS A MORE SIGNIFICANT SHORTWAVE CROSSES MANITOBA AND NORTHWEST ONTARIO. OTHER THAN THE WARM UP ON MON AHEAD OF THE FRONT...NEAR NORMAL TEMPS ARE EXPECTED THROUGH THE REST OF DAYS 4-7. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... EXPECT GENERALLY VFR CONDITIONS TO PREVAIL THROUGH MUCH OF THE FCST PD. THERE IS A CHANCE THAT MVFR FOG AND CEILINGS COULD DEVELOP AT BOTH TAF SITES BETWEEN 06-12Z IMMEDIATELY BEHIND THE PASSAGE OF A COLD FRONT SO DID INCLUDE TEMPO GROUPS IN FOR THIS POSSIBILITY. OTHERWISE...EXPECT ANY FOG/LOW CLOUDS TO DISSIPATE BY LATE FRI MORNING AS DRIER AIR ADVANCES BEHIND THE FRONT. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... FRONT WILL MOVE ACROSS THE LAKE TONIGHT. EXPECT PATCHY FOG TO LINGER OVER THE LAKE TONIGHT AND OVER THE ERN HALF OF THE LAKE FRI BEFORE DISSIPATING WITH DRIER AIR IN WAKE OF COLD FRONT. WINDS WILL GENERALLY REMAIN 20 KT OR LESS THROUGH THE WEEKEND. WINDS MAY APPROACH 25 KT OVER THE ERN HALF OF THE LAKE MON INTO TUE IN ADVANCE OF AN APPROACHING COLD FRONT FROM THE NORTHERN PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM/AVIATION/MARINE...VOSS LONG TERM...JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 130 PM EDT THU AUG 23 2007 AVIATION...MVFR/ISOLATED IFR CIGS HAVE THINNED AT TIMES THROUGH THE MORNING AT THE TAF SITES...BUT ADVANCEMENT NORTHEAST OF A SHORTWAVE ALOFT AND ASSOCIATED PERIOD OF LIGHT RAIN SHOWERS WILL BRING ABOUT A RETURN TO MORE PREVAILING MVFR CIGS BETWEEN 015-030KFT. NOT MUCH SUN FOR THE REMAINDER OF THE DAY...AND THIS WILL ALSO RESULT IN NOT MUCH INSTABILITY DEVELOPING FOR THUNDERSTORMS. SCATTERED TO ISOLATED SHOWERS WILL BE HANGING AROUND THE TAF LOCALES...AND WILL RIDE VCSH INTO THE EARLY EVENING. LOOKING UPSTREAM...STRONGER SHORTWAVE ALOFT WORKING THROUGH IOWA...AND WILL MAKE STEADY PROGRESS NORTHEAST AND INTO NRN LOWER THIS EVENING. NUMEROUS SHOWERS AND STORMS WILL DEVELOP AHEAD OF THIS FEATURE THROUGH THE AFTERNOON OUT TO OUR WEST...THEN ARRIVE AT TVC AROUND 00Z...PLN/APN AROUND 01-03Z. MUCH MORE INSTABILITY WEST OF HERE...BUT WE ARE EXPECTED TO GAIN ADDITIONAL INSTABILITY INTO THE EVENING...THAT MIGHT HELP SUSTAIN SOME OF THE STRONGER STORMS FOR A POSSIBLE SHOT AT STRONG WIND GUSTS. WILL BE MONITORING THIS DEVELOPMENT THROUGH THE AFTERNOON FOR POTENTIAL TAF UPDATES. AM EXPECTING MUCH OF THIS ACTIVITY TO EXIT BY 07Z OR SO...BUT THIS IS UNCERTAIN AT THIS POINT. SMD && .UPDATE...SKIES CLEARED AHEAD OF MCV NOW RUNNING TOWARD CENTRAL LAKE MICHIGAN...WITH THE FOG LONG GONE FROM EASTERN UPPER...BUT LOW CLOUDS REMAIN LOCKED IN. BIG QUESTION FOR THE AFTERNOON WAS WHETHER OR NOT WE WOULD GET ANY INSTABILITY DEVELOPING...BUT LOOKING AT EXTENSIVE LOW CLOUD SHIELD ASSOCIATED WITH THE MCV...AND AREA OF SHOWERS RUNNING THROUGH MANISTEE AREA...THIS IS NOT LIKELY TO HAPPEN. WOULD ONLY EXPECT THE SCATTERED RAIN SHOWERS TO CONTINUE PRESSING THROUGH NRN LOWER...WITH POSSIBLY SOME FURTHER DEVELOPMENT. THUNDER WAS NOT WITH THIS SYSTEM...NOR IS IT ANTICIPATED. THE ONLY CHANCE FOR THUNDER FOR THE REMAINDER OF THE DAY APPEARS TO BE NEAR THE SAG BAY...IF THEY CAN CLEAR...AND AGAIN...THIS NOT SO MUCH THE EXPECTATION. UPSTREAM...BETTER SHORTWAVE WILL MOVE THROUGH THE IOWA REGION...AND SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP AHEAD OF THIS FEATURE. THIS WAVE IS ALREADY SUSTAINING AN AREA OF SHOWERS AND SOME STORMS...AND AS THE AFTERNOON PROGRESSES...ADDITIONAL STORMS WILL FIRE...IN MUCH MORE UNSTABLE ENVIRONMENT IN IOWA/NRN IL/SRN WI. TRACKING THIS AREA OF PRECIPITATION BRINGS IT INTO THE MANISTEE AREA AROUND 23Z...AND THROUGH ALPENA BY 03Z. DURATION OF THIS PRECIPITATION IS TOUGH TO DISCERN...BUT PINPOINTING BETWEEN 00Z AND 07Z. SEVERE CHANCES...NOT SO MUCH THIS AFTERNOON AND EVENING WITHOUT DESTABILIZATION/HEATING. FOR THE NIGHT...HAVE TO SEE HOW MUCH DEVELOPMENT/STRENGTHENING CAN OCCUR WITH STORMS AHEAD OF THE STRONGER WAVE. RIGHT NOW...SEVERE CHANCES FOR DAMAGING WINDS TO 60 MPH ARE STILL EXPECTED...BUT PRIMARILY ACROSS SRN LOWER. THERE IS A SMALL CHANCE THAT AREAS SOUTH OF M-72 IN NRN LOWER COULD SEE SOME ACTION...BUT WILL HAVE TO MONITOR STORM ORGANIZATION UPSTREAM TO SEE HOW FAR NORTH THIS THREAT WILL GO. SMD && DISCUSSION...ISSUED 433 AM EARLY MORNING SURFACE/MOSAIC RADAR/UPPER AIR/SATELLITE AND RUC ANALYSIS SHOWS ONGOING LINE OF CONVECTION...STRETCHING FROM EXTREME SOUTHEAST PARTS OF OUR CWA SOUTHWEST INTO EASTERN KANSAS...ONCE AGAIN CONVOLUTING SURFACE PRESSURE FIELDS OVER THE LAKES REGION. WHILE RATHER DIFFUSE AT THE MOMENT...IT APPEARS OUTFLOW FROM CONVECTION HAS BEGUN PROCESS OF REESTABLISHING STATIONARY FRONT (AFTER PLOWING ACROSS NORTHERN MICHIGAN THIS AFTERNOON AS A WARM FRONT) BACK SOUTH ACROSS SOUTHERN LOWER MICHIGAN WEST INTO THE CENTRAL PLAINS. MUCH LIKE LAST SEVERAL DAYS...WARM MOIST ASCENT ON NOSE OF MODEST 850MB LOW LEVEL JET (850MB PROFILE DATA SHOWING 25 TO 35 KNOT SOUTHERLY FLOW OVER CENTRAL PLAINS) PERPENDICULARLY BISECTING THIS EAST/WEST BOUNDARY...COINCIDENT WITH SOME LOW AMPLITUDE SHORTWAVES TRAVERSING THE MID LEVEL SOUTHWEST FLOW...ONCE AGAIN SERVING AS THE IMPETUS FOR THE ONGOING CONVECTIVE COMPLEXES. AS FOR NORTHERN MICHIGAN WEATHER...BESIDES AFOREMENTIONED NORTHERN EXTENT OF CENTRAL MICHIGAN MCS SKIMMING OUR SOUTHERN ZONES...REST OF AREA GENERALLY CLOUDY TO PARTLY CLOUDY WITH A COMBINATION OF HIGH LEVEL CONVECTIVE DEBRIS AS WELL AS SOME LOW OVERCAST AS MOISTURE GETS TRAPPED BELOW STRENGTHENING NOCTURNAL INVERSION. BIGGEST CONCERN FOR OVERNIGHT WEATHER RESIDES ACROSS EASTERN UPPER MICHIGAN WHERE LIGHT TO CALM WINDS AND INCREASING LOW LEVEL MOISTURE HAS LED TO AREAS OF DENSE FOG. RATHER MILD NIGHT...EVEN BY LATE AUGUST STANDARDS...WITH TEMPERATURES IN THE MID 60S TO LOW 70S. FORECAST CONCERNS FOR THE SHORT TERM ARE WHEN/IF SHOWERS AND THUNDERSTORMS WILL ADVANCE NORTH INTO THE AREA. SEVERE ASSESSMENT WILL ALSO HAVE TO BE ADDRESSED AS SPC GRAPHICS MAINTAIN A SLIGHT RISK FOR MUCH OF NORTHERN LOWER MICHIGAN THURSDAY INTO THURSDAY NIGHT. TODAY...RIGHT OFF THE BAT WOULD LIKE TO STATE THIS IS A VERY CHALLENGING...AND SOMEWHAT LOW CONFIDENCE...FORECAST AS CONVECTIVE OUTFLOWS HIGHLY DICTATE EXACT FRONTAL BOUNDARY PLACEMENT AND AS MODELS CONTINUE TO STRUGGLE WITH BOTH PROPER INITIATION (MOST HAVE NO SEMBLANCE OF EXTENT OF ONGOING CONVECTION) AND CONVECTIVE FEEDBACK ISSUES. LIKE LAST SEVERAL DAYS...BIGGEST CHALLENGE IS DETERMINING NORTHWARD EXTENT OF WARM FRONTAL PUSH AS NEXT IN SERIES OF SHORTWAVES...SEEN CLEARLY ON WATER VAPOR IMAGERY OVER CENTRAL KANSAS...GLIDES NORTHEAST INTO THE LAKES REGION THIS EVENING. WITH MODELS STRUGGLING AS SUCH...WILL RELY HIGHLY ON PATTERN RECOGNITION AND RECENT PAST HISTORY TO DETERMINE PRECIPITATION CHANCES TODAY. GUT FEELING IS WITH MAGNITUDE OF CONVECTION TO OUR SOUTH THAT ACTIVE BAROCLINIC ZONE WILL STRUGGLE TO ADVANCE NORTH INTO THE AREA. THUS...WILL TREND FORECAST SIGNIFICANTLY IN THIS DIRECTION...TAPERING POPS SOUTH TO NORTH AND KEEPING EVERYTHING IN CHANCE CATEGORY. WOULD EXPECT A GRADUAL INCREASE IN SHOWER AND THUNDERSTORM COVERAGE THROUGH THE DAY (ALBEIT STAYING SCATTERED) AS DESTABILIZATION (THINKING WE WILL AT LEAST GET SOME BREAKS IN THE OVERCAST) AND MID LEVEL DYNAMICS FROM APPROACHING AFOREMENTIONED KANSAS SHORTWAVE OVERSPREAD THE AREA. SPEAKING OF INSTABILITY...IF MODEL DERIVED POINT SOUNDINGS CAN BE BELIEVED THROUGH THEIR VERTICAL STRUCTURE (A BIG IF)...ML CAPE OVER NORTHERN LOWER THIS AFTERNOON AND EVENING APPROACHES 500 TO 1000 J/KG. THIS COMBINED WITH INCREASING 0-6KM BULK SHEAR THAT APPROACHES 35 TO 40 KNOTS AS 40 TO 50 KNOT 500MB SPEED MAX CUT ACROSS THE AREA...MAY BE ENOUGH FOR A FEW SEVERE THUNDERSTORMS LATER THIS AFTERNOON AND EVENING. PRIMARY CONCERN WOULD BE WIND GUSTS APPROACHING 60MPH AS LARGE HAIL THREAT WOULD BE MINIMAL GIVEN HIGH (14.5KFT) FREEZING HEIGHTS. HEAVY RAIN ALSO A DISTINCT POSSIBILITY IN ANY THUNDERSTORMS WITH PWATS ON THE ORDER OF 1.90 INCHES AND DECENT WARM CLOUD DEPTH. LIKE YESTERDAY...HIGH BUST POTENTIAL ON TEMPERATURES OWNING TO AMOUNT OF SUNSHINE. WITH SOME SUN EXPECTED...HAVE SIDED WITH WARMER END OF GUIDANCE WITH HIGHS RANGING FROM THE UPPER 70S NORTH TO THE MID 80S SOUTH. TONIGHT...MID LEVEL HEIGHT FALLS AND APPROACHING NORTHERN PLAINS COLD FRONT WILL KEEP THE THREAT OF SHOWERS AND STORMS GOING THROUGH THE NIGHT. FOR REASONS MENTIONED ABOVE...EXPECT POSSIBLE SEVERE THREAT FOR NORTHERN LOWER MICHIGAN TO CONTINUE INTO THE EARLY MORNING HOURS...PER SPC DAY ONE OUTLOOK. GIVEN OVERALL LACK OF CONFIDENCE ON LOW LEVEL BOUNDARY PLACEMENTS AND STRENGTH OF MID LEVEL WAVES...HAVE GONE AHEAD AND DROPPED LIKELY WORDING TO CHANCE CATEGORY ACROSS THE BOARD. MILD WEATHER CONTINUES WITH LOWS ONLY DROPPING INTO THE LOW TO MID 60S. TENTATIVELY NOT EXPECTING A SIMILAR FOG SCENARIO AS SEEN TONIGHT AS WINDS SHOULD STAY UP ENOUGH TO PREVENT GOOD FOG FORMATION. FRIDAY AND FRIDAY NIGHT...STARTING TO BELIEVE FRIDAY AFTERNOON AND EVENING MIGHT BE OUR BEST CHANCE TO GET SOME WIDESPREAD RAIN AS MOST POTENT SHORTWAVE OF THE BUNCH...DIVING INTO THE PACIFIC NORTHWEST THIS MORNING...CUTS INTO THE NORTHERN PLAINS. THIS COULD LEAD TO DECENT WAVE DEVELOPMENT ON SOUTHERN FLANK OF QUASI-STATIONARY FRONT EXTENDING FROM THE NORTHERN LAKES INTO THE CENTRAL PLAINS...WHICH THEN SHOULD RIDE NORTHEAST UP THE FRONTAL BOUNDARY. IF THIS OCCURS...WOULD EXPECT A DECENT SLUG OF SHOWERS AND THUNDERSTORMS TO FOLLOW SUITE...WITH BULK OF ACTIVITY CLEARING THE AREA BY LATER FRIDAY NIGHT. SEVERE THREAT WOULD ALSO RAMP UP IN THE WARM SECTOR (WHICH SHOULD INCLUDE PARTS OR ALL OF NORTHERN LOWER MICHIGAN) AS SHEAR PROFILES INCREASE WITH APPROACH OF THE WAVE. TEMPERATURES LOOK TO REMAIN MILD...WITH HIGHS IN THE MID 70S TO LOW 80S AND OVERNIGHT LOWS IN THE UPPER 50S TO LOW 60S. MSB SATURDAY THRU MONDAY...DEPARTING COLD FRONT WILL CONTINUE TO EXIT SOUTHEAST AWAY FROM OUR CWA ON SATURDAY. WILL MAINTAIN SOME LINGERING SHOWER ACTIVITY DURING THE MORNING HOURS AS RESIDUAL LOW LEVEL MOISTURE INTERACTS WITH ONE FINAL SHORT WAVE TRAVERSING THE CWA. DRY WX WILL RETURN SATURDAY AFTERNOON AS STRONG SURFACE HIGH PRESSURE AND DRY AIR THRU THE COLUMN SETTLE INTO THE REGION. DRY WX WILL PERSIST FOR THE REMAINDER OF THE WEEKEND AND EVEN THRU MONDAY AS HIGH PRESSURE REMAINS IN CONTROL. WILL NEED TO KEEP AN EYE ON THE POTENTIAL FOR PRECIP MONDAY NIGHT AS THE TALE END OF A WARM FRONT LIFTS THRU THE REGION. FOR NOW...WILL KEEP THE FORECAST DRY. TEMPS WILL WARM A FEW DEGREES EACH DAY OVER THE FORECAST PERIOD. HIGHS WILL INCREASE FROM THE MID 70S ON SATURDAY TO THE UPPER 70S SUNDAY AND THEN INTO THE LOWER 80S BY MONDAY. LOW TEMPS WILL WARM FROM AROUND 50 SATURDAY NIGHT TO THE LOWER 50S SUNDAY NIGHT TO THE MID AND UPPER 50S BY MONDAY NIGHT. && .APX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MIZ008-015. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 110 PM EDT THU AUG 23 2007 .UPDATE...SKIES CLEARED AHEAD OF MCV NOW RUNNING TOWARD CENTRAL LAKE MICHIGAN...WITH THE FOG LONG GONE FROM EASTERN UPPER...BUT LOW CLOUDS REMAIN LOCKED IN. BIG QUESTION FOR THE AFTERNOON WAS WHETHER OR NOT WE WOULD GET ANY INSTABILITY DEVELOPING...BUT LOOKING AT EXTENSIVE LOW CLOUD SHIELD ASSOCIATED WITH THE MCV...AND AREA OF SHOWERS RUNNING THROUGH MANISTEE AREA...THIS IS NOT LIKELY TO HAPPEN. WOULD ONLY EXPECT THE SCATTERED RAIN SHOWERS TO CONTINUE PRESSING THROUGH NRN LOWER...WITH POSSIBLY SOME FURTHER DEVELOPMENT. THUNDER WAS NOT WITH THIS SYSTEM...NOR IS IT ANTICIPATED. THE ONLY CHANCE FOR THUNDER FOR THE REMAINDER OF THE DAY APPEARS TO BE NEAR THE SAG BAY...IF THEY CAN CLEAR...AND AGAIN...THIS NOT SO MUCH THE EXPECTATION. UPSTREAM...BETTER SHORTWAVE WILL MOVE THROUGH THE IOWA REGION...AND SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP AHEAD OF THIS FEATURE. THIS WAVE IS ALREADY SUSTAINING AN AREA OF SHOWERS AND SOME STORMS...AND AS THE AFTERNOON PROGRESSES...ADDITIONAL STORMS WILL FIRE...IN MUCH MORE UNSTABLE ENVIRONMENT IN IOWA/NRN IL/SRN WI. TRACKING THIS AREA OF PRECIPITATION BRINGS IT INTO THE MANISTEE AREA AROUND 23Z...AND THROUGH ALPENA BY 03Z. DURATION OF THIS PRECIPITATION IS TOUGH TO DISCERN...BUT PINPOINTING BETWEEN 00Z AND 07Z. SEVERE CHANCES...NOT SO MUCH THIS AFTERNOON AND EVENING WITHOUT DESTABILIZATION/HEATING. FOR THE NIGHT...HAVE TO SEE HOW MUCH DEVELOPMENT/STRENGTHENING CAN OCCUR WITH STORMS AHEAD OF THE STRONGER WAVE. RIGHT NOW...SEVERE CHANCES FOR DAMAGING WINDS TO 60 MPH ARE STILL EXPECTED...BUT PRIMARILY ACROSS SRN LOWER. THERE IS A SMALL CHANCE THAT AREAS SOUTH OF M-72 IN NRN LOWER COULD SEE SOME ACTION...BUT WILL HAVE TO MONITOR STORM ORGANIZATION UPSTREAM TO SEE HOW FAR NORTH THIS THREAT WILL GO. SMD && AVIATION...CHALLENGING TAF CYCLE AS DISORGANIZED SURFACE BOUNDARY HOVERS OVER THE AREA...LEADING TO POSSIBLE SHOWER AND THUNDERSTORM DEVELOPMENT THROUGHOUT THE DAY AND TONIGHT. CURRENT ANALYSIS SHOWS BEST POTENTIAL FOR ANY WIDESPREAD THUNDERSTORM ACTIVITY TO HOLD OFF UNTIL THIS EVENING AND CONTINUE OVERNIGHT. TIMING OF INDIVIDUAL CONVECTIVE COMPLEXES AT THIS JUNCTURE NEARLY IMPOSSIBLE...SO WILL COVER WITH A LONG DURATION VCTS GROUP AT ALL TAF SITES TONIGHT. IF/WHEN STORMS AFFECT TAF SITES...PERIODS OF MVFR OR VFR CONDITIONS WILL BE POSSIBLE...BUT WILL NOT SPECIFICALLY MENTION IN TAFS AT THIS TIME. OTHERWISE...VFR CONDITIONS SHOULD DOMINATE UNDER LIGHT SOUTH TO SOUTHWEST FLOW. MSB && .DISCUSSION...ISSUED 433 AM EARLY MORNING SURFACE/MOSAIC RADAR/UPPER AIR/SATELLITE AND RUC ANALYSIS SHOWS ONGOING LINE OF CONVECTION...STRETCHING FROM EXTREME SOUTHEAST PARTS OF OUR CWA SOUTHWEST INTO EASTERN KANSAS...ONCE AGAIN CONVOLUTING SURFACE PRESSURE FIELDS OVER THE LAKES REGION. WHILE RATHER DIFFUSE AT THE MOMENT...IT APPEARS OUTFLOW FROM CONVECTION HAS BEGUN PROCESS OF REESTABLISHING STATIONARY FRONT (AFTER PLOWING ACROSS NORTHERN MICHIGAN THIS AFTERNOON AS A WARM FRONT) BACK SOUTH ACROSS SOUTHERN LOWER MICHIGAN WEST INTO THE CENTRAL PLAINS. MUCH LIKE LAST SEVERAL DAYS...WARM MOIST ASCENT ON NOSE OF MODEST 850MB LOW LEVEL JET (850MB PROFILE DATA SHOWING 25 TO 35 KNOT SOUTHERLY FLOW OVER CENTRAL PLAINS) PERPENDICULARLY BISECTING THIS EAST/WEST BOUNDARY...COINCIDENT WITH SOME LOW AMPLITUDE SHORTWAVES TRAVERSING THE MID LEVEL SOUTHWEST FLOW...ONCE AGAIN SERVING AS THE IMPETUS FOR THE ONGOING CONVECTIVE COMPLEXES. AS FOR NORTHERN MICHIGAN WEATHER...BESIDES AFOREMENTIONED NORTHERN EXTENT OF CENTRAL MICHIGAN MCS SKIMMING OUR SOUTHERN ZONES...REST OF AREA GENERALLY CLOUDY TO PARTLY CLOUDY WITH A COMBINATION OF HIGH LEVEL CONVECTIVE DEBRIS AS WELL AS SOME LOW OVERCAST AS MOISTURE GETS TRAPPED BELOW STRENGTHENING NOCTURNAL INVERSION. BIGGEST CONCERN FOR OVERNIGHT WEATHER RESIDES ACROSS EASTERN UPPER MICHIGAN WHERE LIGHT TO CALM WINDS AND INCREASING LOW LEVEL MOISTURE HAS LED TO AREAS OF DENSE FOG. RATHER MILD NIGHT...EVEN BY LATE AUGUST STANDARDS...WITH TEMPERATURES IN THE MID 60S TO LOW 70S. FORECAST CONCERNS FOR THE SHORT TERM ARE WHEN/IF SHOWERS AND THUNDERSTORMS WILL ADVANCE NORTH INTO THE AREA. SEVERE ASSESSMENT WILL ALSO HAVE TO BE ADDRESSED AS SPC GRAPHICS MAINTAIN A SLIGHT RISK FOR MUCH OF NORTHERN LOWER MICHIGAN THURSDAY INTO THURSDAY NIGHT. TODAY...RIGHT OFF THE BAT WOULD LIKE TO STATE THIS IS A VERY CHALLENGING...AND SOMEWHAT LOW CONFIDENCE...FORECAST AS CONVECTIVE OUTFLOWS HIGHLY DICTATE EXACT FRONTAL BOUNDARY PLACEMENT AND AS MODELS CONTINUE TO STRUGGLE WITH BOTH PROPER INITIATION (MOST HAVE NO SEMBLANCE OF EXTENT OF ONGOING CONVECTION) AND CONVECTIVE FEEDBACK ISSUES. LIKE LAST SEVERAL DAYS...BIGGEST CHALLENGE IS DETERMINING NORTHWARD EXTENT OF WARM FRONTAL PUSH AS NEXT IN SERIES OF SHORTWAVES...SEEN CLEARLY ON WATER VAPOR IMAGERY OVER CENTRAL KANSAS...GLIDES NORTHEAST INTO THE LAKES REGION THIS EVENING. WITH MODELS STRUGGLING AS SUCH...WILL RELY HIGHLY ON PATTERN RECOGNITION AND RECENT PAST HISTORY TO DETERMINE PRECIPITATION CHANCES TODAY. GUT FEELING IS WITH MAGNITUDE OF CONVECTION TO OUR SOUTH THAT ACTIVE BAROCLINIC ZONE WILL STRUGGLE TO ADVANCE NORTH INTO THE AREA. THUS...WILL TREND FORECAST SIGNIFICANTLY IN THIS DIRECTION...TAPERING POPS SOUTH TO NORTH AND KEEPING EVERYTHING IN CHANCE CATEGORY. WOULD EXPECT A GRADUAL INCREASE IN SHOWER AND THUNDERSTORM COVERAGE THROUGH THE DAY (ALBEIT STAYING SCATTERED) AS DESTABILIZATION (THINKING WE WILL AT LEAST GET SOME BREAKS IN THE OVERCAST) AND MID LEVEL DYNAMICS FROM APPROACHING AFOREMENTIONED KANSAS SHORTWAVE OVERSPREAD THE AREA. SPEAKING OF INSTABILITY...IF MODEL DERIVED POINT SOUNDINGS CAN BE BELIEVED THROUGH THEIR VERTICAL STRUCTURE (A BIG IF)...ML CAPE OVER NORTHERN LOWER THIS AFTERNOON AND EVENING APPROACHES 500 TO 1000 J/KG. THIS COMBINED WITH INCREASING 0-6KM BULK SHEAR THAT APPROACHES 35 TO 40 KNOTS AS 40 TO 50 KNOT 500MB SPEED MAX CUT ACROSS THE AREA...MAY BE ENOUGH FOR A FEW SEVERE THUNDERSTORMS LATER THIS AFTERNOON AND EVENING. PRIMARY CONCERN WOULD BE WIND GUSTS APPROACHING 60MPH AS LARGE HAIL THREAT WOULD BE MINIMAL GIVEN HIGH (14.5KFT) FREEZING HEIGHTS. HEAVY RAIN ALSO A DISTINCT POSSIBILITY IN ANY THUNDERSTORMS WITH PWATS ON THE ORDER OF 1.90 INCHES AND DECENT WARM CLOUD DEPTH. LIKE YESTERDAY...HIGH BUST POTENTIAL ON TEMPERATURES OWNING TO AMOUNT OF SUNSHINE. WITH SOME SUN EXPECTED...HAVE SIDED WITH WARMER END OF GUIDANCE WITH HIGHS RANGING FROM THE UPPER 70S NORTH TO THE MID 80S SOUTH. TONIGHT...MID LEVEL HEIGHT FALLS AND APPROACHING NORTHERN PLAINS COLD FRONT WILL KEEP THE THREAT OF SHOWERS AND STORMS GOING THROUGH THE NIGHT. FOR REASONS MENTIONED ABOVE...EXPECT POSSIBLE SEVERE THREAT FOR NORTHERN LOWER MICHIGAN TO CONTINUE INTO THE EARLY MORNING HOURS...PER SPC DAY ONE OUTLOOK. GIVEN OVERALL LACK OF CONFIDENCE ON LOW LEVEL BOUNDARY PLACEMENTS AND STRENGTH OF MID LEVEL WAVES...HAVE GONE AHEAD AND DROPPED LIKELY WORDING TO CHANCE CATEGORY ACROSS THE BOARD. MILD WEATHER CONTINUES WITH LOWS ONLY DROPPING INTO THE LOW TO MID 60S. TENTATIVELY NOT EXPECTING A SIMILAR FOG SCENARIO AS SEEN TONIGHT AS WINDS SHOULD STAY UP ENOUGH TO PREVENT GOOD FOG FORMATION. FRIDAY AND FRIDAY NIGHT...STARTING TO BELIEVE FRIDAY AFTERNOON AND EVENING MIGHT BE OUR BEST CHANCE TO GET SOME WIDESPREAD RAIN AS MOST POTENT SHORTWAVE OF THE BUNCH...DIVING INTO THE PACIFIC NORTHWEST THIS MORNING...CUTS INTO THE NORTHERN PLAINS. THIS COULD LEAD TO DECENT WAVE DEVELOPMENT ON SOUTHERN FLANK OF QUASI-STATIONARY FRONT EXTENDING FROM THE NORTHERN LAKES INTO THE CENTRAL PLAINS...WHICH THEN SHOULD RIDE NORTHEAST UP THE FRONTAL BOUNDARY. IF THIS OCCURS...WOULD EXPECT A DECENT SLUG OF SHOWERS AND THUNDERSTORMS TO FOLLOW SUITE...WITH BULK OF ACTIVITY CLEARING THE AREA BY LATER FRIDAY NIGHT. SEVERE THREAT WOULD ALSO RAMP UP IN THE WARM SECTOR (WHICH SHOULD INCLUDE PARTS OR ALL OF NORTHERN LOWER MICHIGAN) AS SHEAR PROFILES INCREASE WITH APPROACH OF THE WAVE. TEMPERATURES LOOK TO REMAIN MILD...WITH HIGHS IN THE MID 70S TO LOW 80S AND OVERNIGHT LOWS IN THE UPPER 50S TO LOW 60S. MSB SATURDAY THRU MONDAY...DEPARTING COLD FRONT WILL CONTINUE TO EXIT SOUTHEAST AWAY FROM OUR CWA ON SATURDAY. WILL MAINTAIN SOME LINGERING SHOWER ACTIVITY DURING THE MORNING HOURS AS RESIDUAL LOW LEVEL MOISTURE INTERACTS WITH ONE FINAL SHORT WAVE TRAVERSING THE CWA. DRY WX WILL RETURN SATURDAY AFTERNOON AS STRONG SURFACE HIGH PRESSURE AND DRY AIR THRU THE COLUMN SETTLE INTO THE REGION. DRY WX WILL PERSIST FOR THE REMAINDER OF THE WEEKEND AND EVEN THRU MONDAY AS HIGH PRESSURE REMAINS IN CONTROL. WILL NEED TO KEEP AN EYE ON THE POTENTIAL FOR PRECIP MONDAY NIGHT AS THE TALE END OF A WARM FRONT LIFTS THRU THE REGION. FOR NOW...WILL KEEP THE FORECAST DRY. TEMPS WILL WARM A FEW DEGREES EACH DAY OVER THE FORECAST PERIOD. HIGHS WILL INCREASE FROM THE MID 70S ON SATURDAY TO THE UPPER 70S SUNDAY AND THEN INTO THE LOWER 80S BY MONDAY. LOW TEMPS WILL WARM FROM AROUND 50 SATURDAY NIGHT TO THE LOWER 50S SUNDAY NIGHT TO THE MID AND UPPER 50S BY MONDAY NIGHT. && .APX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MIZ008-015. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1230 PM EDT THU AUG 23 2007 .UPDATE... CONCERNS ARE PCPN CHCS AND COVERAGE THIS AFTERNOON. ORGANIZED CONVECTION/BOWING STRUCTURE OVER ERN IA ASSOCIATED WITH SHORTWAVE MOVING THROUGH ERN NEBRASKA. 12Z RUC AND NAM INDICATE A JUICY ENVIRONMENT DOWNSTREAM OVER SRN WI AND NRN IL WHERE MLCAPES ARE FCST TO BE 1000-1500 J/KG. EXPECT MCS/BOW ECHO TO PROPAGATE ACROSS THESE AREAS THIS AFTERNOON WHERE SPC IS CONTEMPLATING A SVR TSTM WATCH. I AM A BIT CONCERNED THAT THIS ORGANIZED STORM STRUCTURE MAY ROB DEEP MOISTURE FOR STORMS TO FORM OVER UPR MI THIS AFTERNOON. CLOUDS LINGERING OVER CENTRAL AND ERN UPR MI MAY ALSO LIMIT HEATING/INSTABILITY THIS AFTERNOON DESPITE MID-UPR 60S DEWPOINTS. MODIFIED MODEL SNDGS AND FCST INSTABILITY PARAMETERS ALSO SEEM TO SUGGEST MARGINAL ENVIRONMENT AT BEST FOR CONVECTION TO OCCUR. GIVEN THAT MODEL AND RADAR TRENDS BOTH SUGGEST A DRIER FCST THIS AFTERNOON FOR CENTRAL AND ERN PORTIONS OF THE CWA...HAVE DECIDED TO TRIM BACK RAIN CHCS TO JUST THE SCNTRL SECTIONS. HIGHER DEWPOINTS (UPR 60S TO NEAR 70F) COULD ALLOW NRN FRINGE OF MCS TO CLIP THESE AREAS AND BRING IN SOME SCT SHRA/TSRA LATE THIS AFTERNOON SO WILL KEEP LOW CHC POPS FOR RAIN THERE. EXPECT THE REST OF THE CWA TO STAY DRY. .DISCUSSION... MAIN FORECAST CONCERN IS PRECIP. CHANCES FOR TODAY AND TONIGHT GIVEN LATEST GUIDANCE AND MODEL TRENDS...DECIDED TO SIGNIFICANTLY MODIFY THE FORECAST FOR TODAY. 850MB ISOTHERMAL GRADIENT...CURRENTLY SITUATED ACROSS CENTRAL WI AND INTO LOWER MI WILL SHIFT NORTH THROUGHOUT THE DAY TODAY...BUT AS THIS HAPPENS DRY AIR FROM THE WEST WILL INHIBIT BOTH ITS MOVEMENT NORTH AND MOISTENING OF THE LOWER LEVELS OVER OUR CWA. THE OPPORTUNITY FOR A WIDESPREAD SOAKING RAIN JUST DOES NOT LOOK GOOD AT ALL. TRIMMED BACK WEATHER GRIDS AND KEPT PRECIP. CHANCES ONLY IN THE SOUTH CENTRAL THEN EASTWARD. EVEN THESE AREAS DON`T APPEAR TO BE GOOD CANDIDATES FOR RAIN. EACH MODEL...GFS...NAM...GEM...UKMET HAVE BEEN RESOLVING THIS ISSUE BETTER OVER EACH CONSECUTIVE RUN AND HAVE KEPT PRECIP CONFINED MAINLY TO THE SOUTH AND EAST. MOST NOTABLY WITH THE NAM WHICH IS NO LONGER TRYING TO PUT 3 INCHES OF RAIN OVER OUR CWA. NOT ENOUGH CONFIDENCE TO REMOVE PRECIP...THOUGH IT REALLY DOESN`T LOOK GOOD FOR RAIN TODAY. USED HPC IDEA FOR PRECIP. TODAY...JUST TRIMMED DOWN THE VALUES. BY THIS EVENING A SHORTWAVE CURRENTLY OVER WYOMING WILL SLIDE EAST AND LOOKS TO HAVE ENOUGH ENERGY AND AVAILABLE MOISTURE TO PRODUCE PRECIP. TONIGHT AND INTO EARLY FRIDAY MORNING. FRIDAY EVENING INTO SATURDAY LOOKS TO BE DECENT AS WEAK SURFACE RIDGING UNDERNEATH UPPER LEVEL TROUGH PASSES THROUGH THE CWA. 500MB VORT SLIDES THROUGH SATURDAY BUT LACKS ENOUGH MOISTURE AT THE MOMENT TO ALLOW FOR POPS ON SATURDAY. AS THE UPPER LEVEL TROUGH PASSES THROUGH SAT EVENING...FLOW BECOMES ZONAL AS HIGH PRESSURE BEGINS BUILDING OVER THE SOUTHEASTERN US. S/W PASSING OVER THE TOP OF THIS RIDGE YIELD NICE SETUP FOR PRECIP. POTENTIAL THROUGH TUESDAY. NO GOOD REASON TO CHANGE WX GRIDS DURING THIS TIME FRAME. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... VLIFR CIGS AND VIS CONDITIONS WILL CONTINUE A LITTLE LONGER AT KSAW WITH FOG AND LOW CLOUDS WHICH WILL BURN OFF RAPIDLY WITH MIXING FROM DIURNAL HEATING. VFR CONDITIONS WILL THEN CONTINUE THROUGH 12Z AT KSAW. KCMX WILL CONTINUE WITH VFR AS WELL. TOOK CHANCE OF RAIN OUT OF TAFS AS APPEARS VERY LOW NOW WITH BOUNDARY WELL TO THE SOUTH WHICH WILL ROB AREA OF MOISTURE. CHANCE OF RAIN IS LOW ENOUGH TO KEEP OUT OF TAFS AND LATER SHIFTS CAN MONITOR TO SEE IF IT NEEDS TO BE PUT BACK IN. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... FOG WILL CONTINUE ON THE EASTERN PART OF THE LAKE THIS MORNING BEFORE MIXING OUT THIS AFTERNOON AS DRIER AIR TRIES TO MOVE INTO THE REGION. WINDS WILL CONTINUE TO REMAIN UNDER 20 KT ON THE LAKE THROUGH THE PERIOD. WINDS MAY APPROACH 25 KT ON FRI AS A FRONT MOVES THROUGH. NO GALES FORESEEN THROUGH THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...VOSS DISCUSSION...PEARSON AVIATION/MARINE...GM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 735 AM EDT THU AUG 23 2007 .AVIATION...CHALLENGING TAF CYCLE AS DISORGANIZED SURFACE BOUNDARY HOVERS OVER THE AREA...LEADING TO POSSIBLE SHOWER AND THUNDERSTORM DEVELOPMENT THROUGHOUT THE DAY AND TONIGHT. CURRENT ANALYSIS SHOWS BEST POTENTIAL FOR ANY WIDESPREAD THUNDERSTORM ACTIVITY TO HOLD OFF UNTIL THIS EVENING AND CONTINUE OVERNIGHT. TIMING OF INDIVIDUAL CONVECTIVE COMPLEXES AT THIS JUNCTURE NEARLY IMPOSSIBLE...SO WILL COVER WITH A LONG DURATION VCTS GROUP AT ALL TAF SITES TONIGHT. IF/WHEN STORMS AFFECT TAF SITES...PERIODS OF MVFR OR VFR CONDITIONS WILL BE POSSIBLE...BUT WILL NOT SPECIFICALLY MENTION IN TAFS AT THIS TIME. OTHERWISE...VFR CONDITIONS SHOULD DOMINATE UNDER LIGHT SOUTH TO SOUTHWEST FLOW. MSB && .DISCUSSION...ISSUED 433 AM EARLY MORNING SURFACE/MOSAIC RADAR/UPPER AIR/SATELLITE AND RUC ANALYSIS SHOWS ONGOING LINE OF CONVECTION...STRETCHING FROM EXTREME SOUTHEAST PARTS OF OUR CWA SOUTHWEST INTO EASTERN KANSAS...ONCE AGAIN CONVOLUTING SURFACE PRESSURE FIELDS OVER THE LAKES REGION. WHILE RATHER DIFFUSE AT THE MOMENT...IT APPEARS OUTFLOW FROM CONVECTION HAS BEGUN PROCESS OF REESTABLISHING STATIONARY FRONT (AFTER PLOWING ACROSS NORTHERN MICHIGAN THIS AFTERNOON AS A WARM FRONT) BACK SOUTH ACROSS SOUTHERN LOWER MICHIGAN WEST INTO THE CENTRAL PLAINS. MUCH LIKE LAST SEVERAL DAYS...WARM MOIST ASCENT ON NOSE OF MODEST 850MB LOW LEVEL JET (850MB PROFILE DATA SHOWING 25 TO 35 KNOT SOUTHERLY FLOW OVER CENTRAL PLAINS) PERPENDICULARLY BISECTING THIS EAST/WEST BOUNDARY...COINCIDENT WITH SOME LOW AMPLITUDE SHORTWAVES TRAVERSING THE MID LEVEL SOUTHWEST FLOW...ONCE AGAIN SERVING AS THE IMPETUS FOR THE ONGOING CONVECTIVE COMPLEXES. AS FOR NORTHERN MICHIGAN WEATHER...BESIDES AFOREMENTIONED NORTHERN EXTENT OF CENTRAL MICHIGAN MCS SKIMMING OUR SOUTHERN ZONES...REST OF AREA GENERALLY CLOUDY TO PARTLY CLOUDY WITH A COMBINATION OF HIGH LEVEL CONVECTIVE DEBRIS AS WELL AS SOME LOW OVERCAST AS MOISTURE GETS TRAPPED BELOW STRENGTHENING NOCTURNAL INVERSION. BIGGEST CONCERN FOR OVERNIGHT WEATHER RESIDES ACROSS EASTERN UPPER MICHIGAN WHERE LIGHT TO CALM WINDS AND INCREASING LOW LEVEL MOISTURE HAS LED TO AREAS OF DENSE FOG. RATHER MILD NIGHT...EVEN BY LATE AUGUST STANDARDS...WITH TEMPERATURES IN THE MID 60S TO LOW 70S. FORECAST CONCERNS FOR THE SHORT TERM ARE WHEN/IF SHOWERS AND THUNDERSTORMS WILL ADVANCE NORTH INTO THE AREA. SEVERE ASSESSMENT WILL ALSO HAVE TO BE ADDRESSED AS SPC GRAPHICS MAINTAIN A SLIGHT RISK FOR MUCH OF NORTHERN LOWER MICHIGAN THURSDAY INTO THURSDAY NIGHT. TODAY...RIGHT OFF THE BAT WOULD LIKE TO STATE THIS IS A VERY CHALLENGING...AND SOMEWHAT LOW CONFIDENCE...FORECAST AS CONVECTIVE OUTFLOWS HIGHLY DICTATE EXACT FRONTAL BOUNDARY PLACEMENT AND AS MODELS CONTINUE TO STRUGGLE WITH BOTH PROPER INITIATION (MOST HAVE NO SEMBLANCE OF EXTENT OF ONGOING CONVECTION) AND CONVECTIVE FEEDBACK ISSUES. LIKE LAST SEVERAL DAYS...BIGGEST CHALLENGE IS DETERMINING NORTHWARD EXTENT OF WARM FRONTAL PUSH AS NEXT IN SERIES OF SHORTWAVES...SEEN CLEARLY ON WATER VAPOR IMAGERY OVER CENTRAL KANSAS...GLIDES NORTHEAST INTO THE LAKES REGION THIS EVENING. WITH MODELS STRUGGLING AS SUCH...WILL RELY HIGHLY ON PATTERN RECOGNITION AND RECENT PAST HISTORY TO DETERMINE PRECIPITATION CHANCES TODAY. GUT FEELING IS WITH MAGNITUDE OF CONVECTION TO OUR SOUTH THAT ACTIVE BAROCLINIC ZONE WILL STRUGGLE TO ADVANCE NORTH INTO THE AREA. THUS...WILL TREND FORECAST SIGNIFICANTLY IN THIS DIRECTION...TAPERING POPS SOUTH TO NORTH AND KEEPING EVERYTHING IN CHANCE CATEGORY. WOULD EXPECT A GRADUAL INCREASE IN SHOWER AND THUNDERSTORM COVERAGE THROUGH THE DAY (ALBEIT STAYING SCATTERED) AS DESTABILIZATION (THINKING WE WILL AT LEAST GET SOME BREAKS IN THE OVERCAST) AND MID LEVEL DYNAMICS FROM APPROACHING AFOREMENTIONED KANSAS SHORTWAVE OVERSPREAD THE AREA. SPEAKING OF INSTABILITY...IF MODEL DERIVED POINT SOUNDINGS CAN BE BELIEVED THROUGH THEIR VERTICAL STRUCTURE (A BIG IF)...ML CAPE OVER NORTHERN LOWER THIS AFTERNOON AND EVENING APPROACHES 500 TO 1000 J/KG. THIS COMBINED WITH INCREASING 0-6KM BULK SHEAR THAT APPROACHES 35 TO 40 KNOTS AS 40 TO 50 KNOT 500MB SPEED MAX CUT ACROSS THE AREA...MAY BE ENOUGH FOR A FEW SEVERE THUNDERSTORMS LATER THIS AFTERNOON AND EVENING. PRIMARY CONCERN WOULD BE WIND GUSTS APPROACHING 60MPH AS LARGE HAIL THREAT WOULD BE MINIMAL GIVEN HIGH (14.5KFT) FREEZING HEIGHTS. HEAVY RAIN ALSO A DISTINCT POSSIBILITY IN ANY THUNDERSTORMS WITH PWATS ON THE ORDER OF 1.90 INCHES AND DECENT WARM CLOUD DEPTH. LIKE YESTERDAY...HIGH BUST POTENTIAL ON TEMPERATURES OWNING TO AMOUNT OF SUNSHINE. WITH SOME SUN EXPECTED...HAVE SIDED WITH WARMER END OF GUIDANCE WITH HIGHS RANGING FROM THE UPPER 70S NORTH TO THE MID 80S SOUTH. TONIGHT...MID LEVEL HEIGHT FALLS AND APPROACHING NORTHERN PLAINS COLD FRONT WILL KEEP THE THREAT OF SHOWERS AND STORMS GOING THROUGH THE NIGHT. FOR REASONS MENTIONED ABOVE...EXPECT POSSIBLE SEVERE THREAT FOR NORTHERN LOWER MICHIGAN TO CONTINUE INTO THE EARLY MORNING HOURS...PER SPC DAY ONE OUTLOOK. GIVEN OVERALL LACK OF CONFIDENCE ON LOW LEVEL BOUNDARY PLACEMENTS AND STRENGTH OF MID LEVEL WAVES...HAVE GONE AHEAD AND DROPPED LIKELY WORDING TO CHANCE CATEGORY ACROSS THE BOARD. MILD WEATHER CONTINUES WITH LOWS ONLY DROPPING INTO THE LOW TO MID 60S. TENTATIVELY NOT EXPECTING A SIMILAR FOG SCENARIO AS SEEN TONIGHT AS WINDS SHOULD STAY UP ENOUGH TO PREVENT GOOD FOG FORMATION. FRIDAY AND FRIDAY NIGHT...STARTING TO BELIEVE FRIDAY AFTERNOON AND EVENING MIGHT BE OUR BEST CHANCE TO GET SOME WIDESPREAD RAIN AS MOST POTENT SHORTWAVE OF THE BUNCH...DIVING INTO THE PACIFIC NORTHWEST THIS MORNING...CUTS INTO THE NORTHERN PLAINS. THIS COULD LEAD TO DECENT WAVE DEVELOPMENT ON SOUTHERN FLANK OF QUASI-STATIONARY FRONT EXTENDING FROM THE NORTHERN LAKES INTO THE CENTRAL PLAINS...WHICH THEN SHOULD RIDE NORTHEAST UP THE FRONTAL BOUNDARY. IF THIS OCCURS...WOULD EXPECT A DECENT SLUG OF SHOWERS AND THUNDERSTORMS TO FOLLOW SUITE...WITH BULK OF ACTIVITY CLEARING THE AREA BY LATER FRIDAY NIGHT. SEVERE THREAT WOULD ALSO RAMP UP IN THE WARM SECTOR (WHICH SHOULD INCLUDE PARTS OR ALL OF NORTHERN LOWER MICHIGAN) AS SHEAR PROFILES INCREASE WITH APPROACH OF THE WAVE. TEMPERATURES LOOK TO REMAIN MILD...WITH HIGHS IN THE MID 70S TO LOW 80S AND OVERNIGHT LOWS IN THE UPPER 50S TO LOW 60S. MSB SATURDAY THRU MONDAY...DEPARTING COLD FRONT WILL CONTINUE TO EXIT SOUTHEAST AWAY FROM OUR CWA ON SATURDAY. WILL MAINTAIN SOME LINGERING SHOWER ACTIVITY DURING THE MORNING HOURS AS RESIDUAL LOW LEVEL MOISTURE INTERACTS WITH ONE FINAL SHORT WAVE TRAVERSING THE CWA. DRY WX WILL RETURN SATURDAY AFTERNOON AS STRONG SURFACE HIGH PRESSURE AND DRY AIR THRU THE COLUMN SETTLE INTO THE REGION. DRY WX WILL PERSIST FOR THE REMAINDER OF THE WEEKEND AND EVEN THRU MONDAY AS HIGH PRESSURE REMAINS IN CONTROL. WILL NEED TO KEEP AN EYE ON THE POTENTIAL FOR PRECIP MONDAY NIGHT AS THE TALE END OF A WARM FRONT LIFTS THRU THE REGION. FOR NOW...WILL KEEP THE FORECAST DRY. TEMPS WILL WARM A FEW DEGREES EACH DAY OVER THE FORECAST PERIOD. HIGHS WILL INCREASE FROM THE MID 70S ON SATURDAY TO THE UPPER 70S SUNDAY AND THEN INTO THE LOWER 80S BY MONDAY. LOW TEMPS WILL WARM FROM AROUND 50 SATURDAY NIGHT TO THE LOWER 50S SUNDAY NIGHT TO THE MID AND UPPER 50S BY MONDAY NIGHT. && .APX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MIZ008-015. && $$ mi AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE GAYLORD MI 433 AM EDT THU AUG 23 2007 .DISCUSSION...EARLY MORNING SURFACE/MOSAIC RADAR/UPPER AIR/SATELLITE AND RUC ANALYSIS SHOWS ONGOING LINE OF CONVECTION...STRETCHING FROM EXTREME SOUTHEAST PARTS OF OUR CWA SOUTHWEST INTO EASTERN KANSAS...ONCE AGAIN CONVOLUTING SURFACE PRESSURE FIELDS OVER THE LAKES REGION. WHILE RATHER DIFFUSE AT THE MOMENT...IT APPEARS OUTFLOW FROM CONVECTION HAS BEGUN PROCESS OF REESTABLISHING STATIONARY FRONT (AFTER PLOWING ACROSS NORTHERN MICHIGAN THIS AFTERNOON AS A WARM FRONT) BACK SOUTH ACROSS SOUTHERN LOWER MICHIGAN WEST INTO THE CENTRAL PLAINS. MUCH LIKE LAST SEVERAL DAYS...WARM MOIST ASCENT ON NOSE OF MODEST 850MB LOW LEVEL JET (850MB PROFILE DATA SHOWING 25 TO 35 KNOT SOUTHERLY FLOW OVER CENTRAL PLAINS) PERPENDICULARLY BISECTING THIS EAST/WEST BOUNDARY...COINCIDENT WITH SOME LOW AMPLITUDE SHORTWAVES TRAVERSING THE MID LEVEL SOUTHWEST FLOW...ONCE AGAIN SERVING AS THE IMPETUS FOR THE ONGOING CONVECTIVE COMPLEXES. AS FOR NORTHERN MICHIGAN WEATHER...BESIDES AFOREMENTIONED NORTHERN EXTENT OF CENTRAL MICHIGAN MCS SKIMMING OUR SOUTHERN ZONES...REST OF AREA GENERALLY CLOUDY TO PARTLY CLOUDY WITH A COMBINATION OF HIGH LEVEL CONVECTIVE DEBRIS AS WELL AS SOME LOW OVERCAST AS MOISTURE GETS TRAPPED BELOW STRENGTHENING NOCTURNAL INVERSION. BIGGEST CONCERN FOR OVERNIGHT WEATHER RESIDES ACROSS EASTERN UPPER MICHIGAN WHERE LIGHT TO CALM WINDS AND INCREASING LOW LEVEL MOISTURE HAS LED TO AREAS OF DENSE FOG. RATHER MILD NIGHT...EVEN BY LATE AUGUST STANDARDS...WITH TEMPERATURES IN THE MID 60S TO LOW 70S. FORECAST CONCERNS FOR THE SHORT TERM ARE WHEN/IF SHOWERS AND THUNDERSTORMS WILL ADVANCE NORTH INTO THE AREA. SEVERE ASSESSMENT WILL ALSO HAVE TO BE ADDRESSED AS SPC GRAPHICS MAINTAIN A SLIGHT RISK FOR MUCH OF NORTHERN LOWER MICHIGAN THURSDAY INTO THURSDAY NIGHT. TODAY...RIGHT OFF THE BAT WOULD LIKE TO STATE THIS IS A VERY CHALLENGING...AND SOMEWHAT LOW CONFIDENCE...FORECAST AS CONVECTIVE OUTFLOWS HIGHLY DICTATE EXACT FRONTAL BOUNDARY PLACEMENT AND AS MODELS CONTINUE TO STRUGGLE WITH BOTH PROPER INITIATION (MOST HAVE NO SEMBLANCE OF EXTENT OF ONGOING CONVECTION) AND CONVECTIVE FEEDBACK ISSUES. LIKE LAST SEVERAL DAYS...BIGGEST CHALLENGE IS DETERMINING NORTHWARD EXTENT OF WARM FRONTAL PUSH AS NEXT IN SERIES OF SHORTWAVES...SEEN CLEARLY ON WATER VAPOR IMAGERY OVER CENTRAL KANSAS...GLIDES NORTHEAST INTO THE LAKES REGION THIS EVENING. WITH MODELS STRUGGLING AS SUCH...WILL RELY HIGHLY ON PATTERN RECOGNITION AND RECENT PAST HISTORY TO DETERMINE PRECIPITATION CHANCES TODAY. GUT FEELING IS WITH MAGNITUDE OF CONVECTION TO OUR SOUTH THAT ACTIVE BAROCLINIC ZONE WILL STRUGGLE TO ADVANCE NORTH INTO THE AREA. THUS...WILL TREND FORECAST SIGNIFICANTLY IN THIS DIRECTION...TAPERING POPS SOUTH TO NORTH AND KEEPING EVERYTHING IN CHANCE CATEGORY. WOULD EXPECT A GRADUAL INCREASE IN SHOWER AND THUNDERSTORM COVERAGE THROUGH THE DAY (ALBEIT STAYING SCATTERED) AS DESTABILIZATION (THINKING WE WILL AT LEAST GET SOME BREAKS IN THE OVERCAST) AND MID LEVEL DYNAMICS FROM APPROACHING AFOREMENTIONED KANSAS SHORTWAVE OVERSPREAD THE AREA. SPEAKING OF INSTABILITY...IF MODEL DERIVED POINT SOUNDINGS CAN BE BELIEVED THROUGH THEIR VERTICAL STRUCTURE (A BIG IF)...ML CAPE OVER NORTHERN LOWER THIS AFTERNOON AND EVENING APPROACHES 500 TO 1000 J/KG. THIS COMBINED WITH INCREASING 0-6KM BULK SHEAR THAT APPROACHES 35 TO 40 KNOTS AS 40 TO 50 KNOT 500MB SPEED MAX CUT ACROSS THE AREA...MAY BE ENOUGH FOR A FEW SEVERE THUNDERSTORMS LATER THIS AFTERNOON AND EVENING. PRIMARY CONCERN WOULD BE WIND GUSTS APPROACHING 60MPH AS LARGE HAIL THREAT WOULD BE MINIMAL GIVEN HIGH (14.5KFT) FREEZING HEIGHTS. HEAVY RAIN ALSO A DISTINCT POSSIBILITY IN ANY THUNDERSTORMS WITH PWATS ON THE ORDER OF 1.90 INCHES AND DECENT WARM CLOUD DEPTH. LIKE YESTERDAY...HIGH BUST POTENTIAL ON TEMPERATURES OWNING TO AMOUNT OF SUNSHINE. WITH SOME SUN EXPECTED...HAVE SIDED WITH WARMER END OF GUIDANCE WITH HIGHS RANGING FROM THE UPPER 70S NORTH TO THE MID 80S SOUTH. TONIGHT...MID LEVEL HEIGHT FALLS AND APPROACHING NORTHERN PLAINS COLD FRONT WILL KEEP THE THREAT OF SHOWERS AND STORMS GOING THROUGH THE NIGHT. FOR REASONS MENTIONED ABOVE...EXPECT POSSIBLE SEVERE THREAT FOR NORTHERN LOWER MICHIGAN TO CONTINUE INTO THE EARLY MORNING HOURS...PER SPC DAY ONE OUTLOOK. GIVEN OVERALL LACK OF CONFIDENCE ON LOW LEVEL BOUNDARY PLACEMENTS AND STRENGTH OF MID LEVEL WAVES...HAVE GONE AHEAD AND DROPPED LIKELY WORDING TO CHANCE CATEGORY ACROSS THE BOARD. MILD WEATHER CONTINUES WITH LOWS ONLY DROPPING INTO THE LOW TO MID 60S. TENTATIVELY NOT EXPECTING A SIMILAR FOG SCENARIO AS SEEN TONIGHT AS WINDS SHOULD STAY UP ENOUGH TO PREVENT GOOD FOG FORMATION. FRIDAY AND FRIDAY NIGHT...STARTING TO BELIEVE FRIDAY AFTERNOON AND EVENING MIGHT BE OUR BEST CHANCE TO GET SOME WIDESPREAD RAIN AS MOST POTENT SHORTWAVE OF THE BUNCH...DIVING INTO THE PACIFIC NORTHWEST THIS MORNING...CUTS INTO THE NORTHERN PLAINS. THIS COULD LEAD TO DECENT WAVE DEVELOPMENT ON SOUTHERN FLANK OF QUASI-STATIONARY FRONT EXTENDING FROM THE NORTHERN LAKES INTO THE CENTRAL PLAINS...WHICH THEN SHOULD RIDE NORTHEAST UP THE FRONTAL BOUNDARY. IF THIS OCCURS...WOULD EXPECT A DECENT SLUG OF SHOWERS AND THUNDERSTORMS TO FOLLOW SUITE...WITH BULK OF ACTIVITY CLEARING THE AREA BY LATER FRIDAY NIGHT. SEVERE THREAT WOULD ALSO RAMP UP IN THE WARM SECTOR (WHICH SHOULD INCLUDE PARTS OR ALL OF NORTHERN LOWER MICHIGAN) AS SHEAR PROFILES INCREASE WITH APPROACH OF THE WAVE. TEMPERATURES LOOK TO REMAIN MILD...WITH HIGHS IN THE MID 70S TO LOW 80S AND OVERNIGHT LOWS IN THE UPPER 50S TO LOW 60S. MSB SATURDAY THRU MONDAY...DEPARTING COLD FRONT WILL CONTINUE TO EXIT SOUTHEAST AWAY FROM OUR CWA ON SATURDAY. WILL MAINTAIN SOME LINGERING SHOWER ACTIVITY DURING THE MORNING HOURS AS RESIDUAL LOW LEVEL MOISTURE INTERACTS WITH ONE FINAL SHORT WAVE TRAVERSING THE CWA. DRY WX WILL RETURN SATURDAY AFTERNOON AS STRONG SURFACE HIGH PRESSURE AND DRY AIR THRU THE COLUMN SETTLE INTO THE REGION. DRY WX WILL PERSIST FOR THE REMAINDER OF THE WEEKEND AND EVEN THRU MONDAY AS HIGH PRESSURE REMAINS IN CONTROL. WILL NEED TO KEEP AN EYE ON THE POTENTIAL FOR PRECIP MONDAY NIGHT AS THE TALE END OF A WARM FRONT LIFTS THRU THE REGION. FOR NOW...WILL KEEP THE FORECAST DRY. TEMPS WILL WARM A FEW DEGREES EACH DAY OVER THE FORECAST PERIOD. HIGHS WILL INCREASE FROM THE MID 70S ON SATURDAY TO THE UPPER 70S SUNDAY AND THEN INTO THE LOWER 80S BY MONDAY. LOW TEMPS WILL WARM FROM AROUND 50 SATURDAY NIGHT TO THE LOWER 50S SUNDAY NIGHT TO THE MID AND UPPER 50S BY MONDAY NIGHT. && .AVIATION...ISSUED 104 AM RAIN SHOWERS WILL SLOWLY END ACROSS NORTHERN MICHIGAN BY 3 AM. IN THE WAKE OF THE RAIN SHOWERS...DEWPOINTS ARE IN THE MIDDLE 60S...WITH TEMPERATURES AROUND 70. WITH SKIES GRADUALLY BECOMING PARTLY TO MOSTLY CLEAR FOR THE REMAINDER OF THE NIGHT...WOULD EXPECT TO SEE SOME PATCHY FOG AS TEMPERATURES COOL TO THE DEWPOINTS. IN TERMS OF TAF SITES...THE ONLY SITE TO BE AFFECTED WOULD BE KPLN...WHERE VISIBILITIES MAY FALL TO AROUND A MILE BY MORNING. OTHERWISE...MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THE NEXT 9 TO 12 HOURS. A WARM FRONT IS EXPECTED TO LIFT BACK TO THE NORTH TOMORROW...SPAWNING SOME THUNDERSTORMS...BUT TOO MUCH UNCERTAINTY AT THIS POINT TO INCLUDE IN ANY OF THE TAF SITES AND WILL COVER THIS POSSIBILITY WITH VICINITY WORDING. && .APX WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MIZ008-015. && $$ mi AREA FORECAST DISCUSSION...UPDATED FOR AVIATION NATIONAL WEATHER SERVICE MARQUETTE MI 117 AM EDT THU AUG 23 2007 .UPDATE... TRIMMED BACK POPS EXCEPT OVER THE FAR S CNTRL AS RECENT TAMDAR SDNGS/ RAOBS SHOW DRIER AIR ABV SHALLOW MSTR FM MN INTO THE NW ZNS...WHICH LATEST RUC/UKMET SHOW SPREADING ENEWD OVERNGT. LOWERED FCST TEMPS A BIT OVER THE FAR W TO ACCOUNT FOR INFLUX OF THIS DRIER AIR (THE MIXING OF WHICH CAUSED THE DWPT TO FALL AS LOW AS THE UPR 40S AT CMX LATE IN THE AFTN)...BUT CONSIDERABLE HI CLD BLOWING OFF CNVCTN WELL TO THE S WL LIKELY LIMIT THE DIURNAL TEMP FALL DESPITE LGT WINDS. EVEN THOUGH THE DRY AIR WL BE MOVING IN ALF...MORE STUBBORN LLVL MSTR...ESPECIALLY NR LK MI/BAY OF GREEN BAY...WL RESULT IN FOG FORMATION MAINLY OVER THE E HALF. 02Z VSBY AT ISQ DOWN TO 3/4SM IN LGT SLY FLOW OFF THE LK WATERS. WENT WITH ADVISORY IN THE EAST AS VISIBILITIES 1/4 MILE OR MORE AT MOST SITES. .SYNOPSIS... WATER VAPOR LOOP AND RUC ANALYSIS REVEALS UPPER LOW OVER NRN MANITOBA WITH A BROAD RIDGE CENTERED OVER THE GULF COAST STATES. THE RESULTANT SOUTHWEST FLOW BETWEEN THESE FEATURES WILL HELP LIFT A SHORTWAVE FROM THE SRN ROCKIES INTO THE WESTERN GREAT LAKES REGION ON THU. MORNING STRATUS HAS GENERALLY BURNED OFF OVER THE WRN HALF OF THE CWA AS NOTED ON VISIBLE SATELLITE IMAGERY...BUT LOW CLOUDS STILL PERSIST OVER SCNTRL AND ERN COUNTIES. && SHORT TERM (TONIGHT AND THU)... FOCUS FOR THE SHORT TERM WILL BE ON FOG POTENTIAL AND THEN TIMING OF CONVECTION INTO CWFA LATE TONIGHT INTO THU. LINGERING MOIST DEWPOINTS (LOW TO MID 60S) ALONG WITH MID-LVL SUBSIDENCE THIS EVENING COULD LEAD TO MORE STRATUS/FOG FORMATION TONIGHT. MORE WIDESPREAD FOG WILL LIKELY BE OVER ERN HALF COUNTIES WHERE DEVELOPING LIGHT SSE FLOW OFF LAKE MICHIGAN COULD AID LOW-LEVEL MOISTENING. LOOK FOR FOG/LOW STRATUS TO LINGER INTO THU MORNING AS THICKENING MID CLOUDS FROM APPROACHING SRN ROCKIES SHORTWAVE WILL TRAP LOW-LEVEL MOISTURE. MODELS DIFFER ON STRENGTH OF S/WV ENERGY APPROACHING FROM THE SRN ROCKIES. NAM IS SLOWER AND STRONGER WHILE GFS SHOWS A WEAKER AND MORE OPEN WAVE. GIVEN UNCERTAINTY...FOLLOWED ALONG NCEP IDEA OF COMPROMISE SOLN BETWEEN THE UKMET AND GFS. ALTHOUGH 12Z GFS SOLN/QPF FIELDS SUGGEST A MUCH DRIER FCST FOR UPR MI...BELIEVE FAVORABLE UPPER JET DYNAMICS AND RIGHT ENTRANCE REGION FORCING FROM 120+ KT 250 MB JET MAX ALONG WITH ASSOC FGEN FORCING SHOULD ALLOW FOR DECENT RAINFALL...PERHAPS EXCEEDING A HALF AN INCH OVER CENTRAL AND EASTERN PORTIONS OF THE CWFA. WHILE THE RAIN WILL NOT BE A DROUGHT BUSTER IT WILL AID WILDFIRE SUPPRESSION EFFORTS. KEPT IN GOING LIKELY POPS FOR THU AFTERNOON PER PREVIOUS FCST. SPC HAS SRN MNM COUNTY IN SLIGHT RISK FOR DAY2 CONVECTIVE OUTLOOK...BUT SINCE MODELS SUGGEST BEST INSTABILITY AND FORCING SHOULD STAY SOUTH OF FCST AREA AND FACT THAT CLOUDS COULD FURTHER STABILIZE ATMOSPHERE...AVOIDED MENTION OF POTENTIAL SVR IN HWO FOR THU. && .LONG TERM (THURSDAY NIGHT THROUGH WEDNESDAY)... SHORTWAVE OVER THE CENTRAL TO EASTERN CWA WILL BE EXITING TO THE EAST BY 09Z FRIDAY. THE 06Z NAM IS SLOWER THAN THE 06Z GFS AND 00Z CANADIAN BY ROUGHLY 6 HOURS WITH THIS FEATURE. THIS WILL PLAY A SIGNIFICANT ROLL IN THE TIMING OF THE EXITING PRECIPITATION. THE 500MB FEATURE ARE REFLECTED BY A SIMILAR TIMING ISSUE AT THE SURFACE. FOR EXAMPLE...THE GFS WOULD PLACE THE WEAKER SURFACE LOW JUST NORTHEAST OF LAKE SUPERIOR AND LAKE HURON BY 06Z FRIDAY...WHILE THE NAM WOULD PLACE IT OVER NORTHERN LAKE MICHIGAN. INITIAL FEELINGS ON THIS IS TO SIDE CLOSER TO THE GFS AND CANADIAN OUTPUT. HOWEVER...WOULD LIKE TO NOT GO STRAIGHT WITH ITS OUTPUT EITHER...AS THE GFS PLACES A PRECIPITATION MINIMUM OVER EXTREME SOUTHERN MENOMINEE COUNTY WHICH WILL LIKELY NOT VERIFY. THE GFS SOLUTION ALSO SEEMS BE BE BACKED BY THE ECMWF AND UKMET FOR THIS TIME PERIOD. WITH THE LARGE 500MB LOW SPINNING ACROSS THE NORTHERN CANADIAN PROVINCES...LARGER SCALE TROUGHING IS EXPECTED TO COME INTO THE NORTHERN GREAT LAKES REGION SATURDAY AND SUNDAY...WITH ZONAL TO SOUTHWESTERLY TO NORTHEASTERLY FLOW FIGURED THEN THROUGH THE MIDDLE OF THE NEXT WORK WEEK...AS THE 500MB LOW DIVES FARTHER SOUTHWARD AND THE RIDGE GAINS STRENGTH AND PUSHES TO THE MID OHIO VALLEY AND ATLANTIC STATES. SO...IT LOOKS LIKE SATURDAY WILL BE THE NEXT BEST CHANCE FOR RECEIVING ADDITIONAL PRECIPITATION ACROSS PORTIONS OF THE AREA. HOWEVER...THIS SYSTEM MAY BE TOO FAR TO OUR SOUTH TO BRING SIGNIFICANT PRECIPITATION TO THE ENTIRE UPPER PENINUSLA. ONCE AGAIN THE NAM IS SLOWER THAN THE GFS ON TRACKING THE SURFACE LOW UP FROM NORTHERN TEXAS...OKLAHOMA...AND KANSAS FRIDAY AFTERNOON AND TO LOWER MICHIGAN AND SOUTHEASTERN ONTARIO BY 12Z SATURDAY. THIS TIME THE NAM IS ABOUT 9 HOURS SLOWER...AND AS WITH THE THURSDAY EVENING LOW REMAINS STRONGER. HPC PREFERRED A BLEND OF THE ECMWF AND NCEP ENSEMBLE MEAN. GENERALLY FOLLOWED THE HPC GUIDANCE...BUT STILL CUT BACK AND TRIED TO GET A LITTLE BETTER TIMING OF THE PRECIP WITH THE COLD FRONT FOR THE TUESDAY TIME PERIOD. GRID WISE...SOME OF THE LARGER SCALE CHANGES INCLUDED... ADDING FOG TO THE OVERNIGHT HOURS THURSDAY NIGHT...AND INCREASED OVERNIGHT TEMPERATURES SLIGHTLY ESPECIALLY ACROSS THE EAST WHERE CLOUDS WILL LINGER THE LONGEST. FRIDAY AFTERNOON...WITH WINDS BECOMING MORE NORTHERLY ACROSS THE WEST AND STILL A SOUTHERLY PUFF AND WARMER AIR ALOFT EAST...WILL INCREASE TEMPERATURES ACROSS THE EAST AND COOL THINGS OFF A LITTLE MORE WEST. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... SINCE HI CLD HAS THINNED...OPTED TO GO WITH PREDOMINANT IFR VSBYS/CIGS AT SAW WITH UPR DRYING OVER STUBBORN LLVL MOISTURE TNGT. EXPECT CONDITIONS TO IMPROVE BY MID MRNG ON THU WITH ONSET OF DIURNAL HTG/MIXING OF VERY DRY AIR ABV SHALLOW MOIST LYR. DRY AIR SHOWN ON THE 00Z MPX/INL SDNGS WL BE MORE DOMINANT AT CMX...SO FCST NO RADIATION FOG THERE AS DWPT MIXED OUT INTO THE MID-UPR 40S AT CMX YDAY AFTN. WITH LLVL DRY AIR PERSISTING AT CMX THRU THE DAY ON THU...VFR CONDITIONS WL PREDOMINATE. BROUGHT A CHC OF -SHRA AT BOTH SITES TNGT WITH UPR DISTURBANCE RIDING NEWD...BUT LLVL DRY AIR SHOULD KEEP CONDITIONS VFR. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... WINDS WILL REMAIN UNDER 20 KT THROUGH THE FCST PD OVER THE WEST HALF OF LAKE SUPERIOR. WINDS MAY APPROACH 20 KT THU NIGHT INTO FRI AND THEN AGAIN ON SAT AS A COUPLE OF WEAK TROUGHS MOVE ACROSS THE UPPER GREAT LAKES. LINGERING MOIST DEWPOINTS AND THE POTENTIAL FOR RAIN ON THU WILL WARRANT THE MENTION OF FOG OVER LAKE SUPERIOR FOR THE NEXT 24-36 HOURS. && .MQT WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY MIZ006-007-012>014-085 UNTIL 12Z THU. && $$ SYNOPSIS/SHORT TERM...JV LONG TERM...KF AVIATION...GM MARINE...JV UPDATE...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 104 AM EDT THU AUG 23 2007 .AVIATION...RAIN SHOWERS WILL SLOWLY END ACROSS NORTHERN MICHIGAN BY 3 AM. IN THE WAKE OF THE RAIN SHOWERS...DEWPOINTS ARE IN THE MIDDLE 60S...WITH TEMPERATURES AROUND 70. WITH SKIES GRADUALLY BECOMING PARTLY TO MOSTLY CLEAR FOR THE REMAINDER OF THE NIGHT...WOULD EXPECT TO SEE SOME PATCHY FOG AS TEMPERATURES COOL TO THE DEWPOINTS. IN TERMS OF TAF SITES...THE ONLY SITE TO BE AFFECTED WOULD BE KPLN...WHERE VISIBILITIES MAY FALL TO AROUND A MILE BY MORNING. OTHERWISE...MAINLY VFR CONDITIONS ARE EXPECTED THROUGH THE NEXT 9 TO 12 HOURS. A WARM FRONT IS EXPECTED TO LIFT BACK TO THE NORTH TOMORROW...SPAWNING SOME THUNDERSTORMS...BUT TOO MUCH UNCERTAINTY AT THIS POINT TO INCLUDE IN ANY OF THE TAF SITES AND WILL COVER THIS POSSIBILITY WITH VICINITY WORDING. KAS && .UPDATE... /ISSUED 1009 PM EDT WED AUG 22 2007/ LATEST RADAR/SATELLITE/SURFACE ANALYSIS THIS EVENING SHOWS AN INTENSE LINE OF THUNDERSTORMS ROLLING ACROSS SOUTHERN LOWER MICHIGAN...STRETCHING BACK INTO NORTHERN ILLINOIS. THE WARM FRONT WHICH HAD EARLIER PUSHED ALL THE WAY UP TO AROUND THE STRAITS IS NOW VERY ILL DEFINED THANKS TO THE CONVECTION OFF TO THE SOUTH. BY THE TIME ALL IS SAID AND DONE...EXPECT THE WARM FRONT BOUNDARY TO BE REDEFINED ACROSS THE OHIO VALLEY BY TOMORROW MORNING. RADAR TRENDS SUGGEST CONVECTION WILL STAY OUT OF NORTHERN MICHIGAN FOR THE REMAINDER OF THE NIGHT...JUST MISSING GLADWIN AND ARENAC COUNTIES. STRATIFORM PRECIP TO THE NORTH OF THE ACTION DOWN SOUTH HAS CREPT INTO AREAS BETWEEN MANISTEE AND TRAVERSE CITY. HAVE BUMPED UP POPS TO LIKELY SOUTH OF M-72 TO ACCOUNT FOR THE STRATIFORM RAIN THIS EVENING. THIS RAIN SHOULD BE ON THE WAY OUT AFTER 2 AM...WITH JUST SOME SCATTERED SHOWERS SOUTH OF M-55 FOR THE REMAINDER OF THE NIGHT. LOWS TONIGHT LOOK ON TRACK...FALLING INTO THE MIDDLE TO UPPER 60S...WITH A FEW SPOTS FAILING TO FALL BELOW 70...MAINLY NEAR THE LAKES. THAT TAKES US INTO TOMORROW MORNING. CONSIDERING THE WARM FRONT IS NOW SETTING UP TO THE SOUTH...WOULD NOT EXPECT TO SEE MUCH SHOWER AND THUNDERSTORM ACTIVITY AROUND DURING THE EARLY MORNING HOURS. HOWEVER...WITH THE AMOUNT OF CLEARING OFF TO THE WEST OVER NORTHERN WISCONSIN...MOSTLY SUNNY SKIES EARLY IN THE DAY SHOULD HELP TO AGAIN PUSH THE WARM FRONT BACK TO THE NORTH. LIKELY POPS STILL LOOK OK ASSUMING THE WARM FRONT PUSHES BACK TO THE NORTH AROUND MIDDAY...THEN CONTINUED LIKELY POPS WITH THE APPROACH OF A VIGOROUS SHORTWAVE TOMORROW EVENING. CONSIDERING ALL OF THIS IN THE FORECAST...HAVE TRIMMED BACK POPS EARLY TOMORROW MORNING... ESPECIALLY IN THE NORTH...WHERE IT MAY TAKE UNTIL THE AFTERNOON TO SEE ANY SHOWER OR THUNDERSTORM ACTIVITY. KAS && .PREV DISCUSSION... /ISSUED 354 PM EDT WED AUG 22 2007/ A TOUGH FORECAST WITH THE UPCOMING NIGHT INTO THE NEXT COUPLE OF DAYS AS A SFC TROUGH/WARM/STATIONARY/COLD FRONT IS SETTLING IN ACROSS THE REGION. THE WARM FRONT PORTION OF THIS MESS SEEMS TO HAVE RIDDEN IN PRETTY QUICKLY ON THE CLOUD COVER HOLES THAT HAVE ALLOWED THE TEMPERATURES TO RISE TO THE LOWER TO MID 80S. DEWPOINTS HAVE BEEN RISING FAST WELL WITH MID TO UPPER 60S DEWPOINTS AND A FEW AROUND 70F. THE 500 MB RIDGE IS NOW EAST OF THE REGION WITH THE TROUGH NOW TO THE WEST. THIS BRINGS A FLAT TO CYCLONIC FLOW TO THE JET PATTERN OVER N LOWER. THE MAIN CONCERN WILL BE THE CHANCE FOR RAIN AND THUNDERSTORMS OVER THE NEXT COUPLE OF DAYS. TONIGHT/THURSDAY...CURRENTLY, WITH THE TROUGH BEING A LITTLE MORE DEFINED NEAR ANJ, THE SHOWERS HAVE CONTINUED MAINLY OVER WESTERN CHIPPEWA AND LUCE COUNTIES AS WELL AS WHITEFISH BAY. WITH THE SOUNDINGS FROM THE RUC, NAM, AND GFS BEING CAPPED OR NEUTRAL, NONE OF THE INSTABILITY HAS BEEN REALIZED SO WOULD EXPECT THAT NOTHING HAPPENS EARLY, AND THAT THE MAIN ACTION HAPPENS WITH THE GROWING MCS OUT WEST IN IOWA/WISCONSIN ALONG THE NOW STALLED COLD FRONT. SO IN THE GRIDS WILL HAVE SOME SORT OF ESCALATING POPS WITH THE MAIN FOCUS BEING THURSDAY AFTERNOON. THE MODELS ARE QUITE CONFUSING AT THE MOMENT WITH THEM INSISTING THAT IT RAINS FOR ALMOST 48 HOURS. THE GFS HAS FEEDBACK BOMBS AND THE NAM LOOKS TO TRY TO WRING OUT ANY INSTABILITY WITH THE BMJ PARAMETERIZATION, LEADING TO ITS OWN FEEDBACK PROBLEMS, ALTHOUGH IN THE QPF FIELD THE BOMBS LOOK SMALLER. HOWEVER, THE GFS AND NAM TOGETHER ARE POINTING TO SOMETHING LATE THURSDAY AFTERNOON INTO EVENING THAT WOULD COME THROUGH, SO HAVE THE LIKELY THUNDERSTORMS DURING THAT TIME. LUTZ LONGER TERM...COMPLEX WEATHER SCENARIO PANNING OUT. SFC TROUGHS/FRONTAL BOUNDARY EVOLUTION WILL BE DIFFICULT TO DISCERN OVER THE NEXT 60-72 HOURS AND WILL BE KEY FOR FORECASTING WHO GETS RAIN...AND POTENTIALLY...A GOOD SOAKING. WARMTH AND MOISTURE SURGE CURRENTLY ONGOING ACROSS LOWER MICHIGAN IS THE FIRST SIGN THAT WILL EVENTUALLY RESULT IN THE MAIN FRONTAL ZONE (CONTAINING THE DEEPER MOISTURE AND INSTABILITY THAT HAD BEEN TO OUR SOUTH) BECOMING DRAPED ACROSS THE STRAITS REGION AND WAFFLING OVER NRN MICHIGAN OVER THE NEXT 60-72 HOURS. THIS FRONTAL ZONE WILL LAY DOWN THE TRACK FOR 3 SEPARATE SHORTWAVES ALOFT THAT WILL BRING A SUCCESSION OF MODERATE TO POTENTIALLY HEAVY RAINS. THURSDAY NIGHT THROUGH FRIDAY NIGHT...WILL PREFACE THIS DISCUSSION WITH THE FACT THAT EXACT LOCATION OF THE FRONTAL ZONE IS PARAMOUNT. THESE DETAILS WILL BE DIFFICULT TO DISCERN DUE TO EVOLUTION OF CONVECTION AND POTENTIAL OUTFLOWS THAT COULD DRIVE THE BOUNDARY FURTHER IN AND OUT OF NRN MICHIGAN. HOWEVER...AS FOR NOW...CURRENT FRONTAL ZONE IS ALREADY SETTING UP FROM CENTRAL WISCONSIN TO NRN LAKE HURON THIS AFTERNOON. SW FLOW ALOFT WILL BECOME PRETTY MUCH ALIGNED WITH THIS BOUNDARY FROM SW TO NE...WITH A SERIES OF SHORTWAVES SET TO MOVE THROUGH THE REGION. ONE OTHER CAVEAT HERE IS THAT FEEDBACK ISSUES ARE GREAT WITH BOTH MODELS...SO THE INTENSITY OF THESE FEATURES WILL BE MOSTLY DISREGARDED. HOWEVER...THE FACT THAT THEY ARE THERE IS AT LEAST MORE BELIEVABLE. THEREFORE...THE FIRST OF THESE WILL HAVE PUSHED THROUGH BY THURSDAY AFTERNOON...BUT THE SECOND SHORTWAVE WILL BE CLOSE ON IT`S HEELS. NAM SUGGESTS THAT THIS WAVE WILL ARRIVE MAYBE AS EARLY AS LATE THURSDAY AFTERNOON... WHILE THE SLIGHTLY SLOWER GFS SUGGESTS THURSDAY EVENING. THE THIRD WAVE LOOKS TO ARRIVE LATE FRIDAY AFTERNOON AND EVENING. THESE INDIVIDUAL WAVES WILL BE MORE THAN DIFFICULT TO TIME AS WELL...AND WILL ALSO SERVE TO WAVER THE FRONTAL ZONE AROUND NRN MICHIGAN. SEVERE WEATHER WITH EACH OF THESE FEATURES IS A POSSIBILITY AND WILL RESIDE AROUND AND JUST TO THE SOUTH OF THE FRONTAL ZONE (WHICH... AGAIN...EXACT LOCATION WILL BE DIFFICULT TO DISCERN) WHERE THE REGION WILL BE AFFECTED BY RIGHT REAR QUADS OF WEAKISH 100KT UPPER JET...0-6KM BULK SHEAR VALUES RANGING BETWEEN 35-40KTS AND H7-H5 LAPSE RATES LIKELY STEEPENING TO NEAR 6.5C/KM WITH EACH WAVE. ACTUAL AMOUNT OF INSTABILITY IS KEY TOO...AND ATTM...MODELS ARE NOT SHOWING ALOT OF MUCAPE AT NIGHT...WITH AFTERNOON SBCAPE THAT COULD RISE TO NEAR 1500-2000J/KG (OF COURSE HIGHLY DEPENDANT ON CLOUDS/AMOUNT OF HEATING...NOT TO MENTION THIS IS LIKELY THE MOST DIFFICULT PARAMETER TO ASSESS IN THIS SCENARIO). ALL-IN-ALL...WILL NOT GET CUTE WITH THE FORECAST AND KEEP SOME SORT OF CHANCE FOR SHOWERS AND STORMS IN THE FORECAST EACH PERIOD...FOR MOST AREAS THURSDAY NIGHT THROUGH FRIDAY NIGHT. I WILL TRY...RELUCTANTLY...TO NAIL DOWN THE LIKELY TIMES WHICH SEEM TO BE VERY LATE AFTERNOON THURSDAY INTO THURSDAY EVENING...AND AGAIN VERY LATE FRIDAY AFTERNOON/EVENING (WILL KEEP THE LATTER IN 40% CHANCE ZONE RIGHT NOW THOUGH). WITH PRECIPITABLE WATER VALUES BETWEEN 1.5-2.0 INCHES OVER THIS PERIOD OF TIME...A FEW REGIONS MAY GET HEAVY RAINFALL AMOUNTS THROUGH FRIDAY NIGHT. HIGHS WILL RANGING FROM THE LOWER HALF OF THE 70S IN EASTERN UPPER TO THE LOWER HALF OF THE 80S NEAR THE SAG BAY. LOWS SHOULD WIND UP BEING IN THE 60S BOTH THURSDAY NIGHT AND FRIDAY NIGHT...AND RATHER MUGGY. STAY TUNED...DETAILS WILL COME WITH LATER FORECASTS. SATURDAY THROUGH TUESDAY...SLOWER COLD FRONTAL PASSAGE EXPECTED WITH LATEST DATA FOR SATURDAY...WHICH HAS THIS FEATURE MOVING THROUGH THE SAGINAW BAY AREA SATURDAY MORNING. WILL LEAVE SMALL CHANCE FOR PRECIP IN FOR SATURDAY MORNING...BEFORE SFC HIGH PRESSURE AND DRY AIR MOVE IN...THROUGH THE WEEKEND...AND WHAT SHOULD BE AT LEAST TUESDAY. BY TUESDAY...NEXT COLD FRONT EXPECTED TO MOVE THROUGH THE REGION...BUT THIS DOES NOT CURRENTLY LOOK TO BE A STRONG FROPA AND AT THIS POINT...MOISTURE LOOKS RATHER LIMITED. WILL LEAVE CHANCES FOR RAIN OUT OF THE FORECAST ATTM...UNTIL THINGS LOOK MORE CONDUCIVE TO RAIN. SMD && .APX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 100 PM CDT THU AUG 23 2007 .UPDATED FOR AVIATION 18Z AVIATION DISCUSSION. .DISCUSSION... EARLY MORNING WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS SHOW A PAIR OF SHORTWAVES TRAVERSING THE UPPER MIDWEST. THESE WAVES ARE AIDING IN CONVECTIVE DEVELOPMENT OVER EASTERN SD/NE. ASSOCIATED ISENTROPIC UPGLIDE ON THE NAM/GFS PROGGED 305K SURFACE SPREADS ACROSS THE FORECAST AREA THIS MORNING...ACCOMPANIED BY A HEALTHY AREA OF 700MB/850MB THETA E ADVECTION. AREA ALSO REMAINS IN THE FAVORABLE ENTRANCE REGION OF THE UPPER LEVEL JET TODAY. FLASH FLOOD WATCH REMAINS IN PLACE FOR THIS MORNING ACROSS SOUTH CENTRAL MN...WHERE PWATS ARE AROUND 2 INCHES. EXPECT EXTENSIVE CLOUD COVER AND PRECIPITATION TO HINDER WARMING TODAY...SO HAVE UNDERCUT GUIDANCE SUBSTANTIALLY...WITH FORECAST HIGHS GENERALLY BETWEEN 70 AND 75. H85 FRONT SHOULD STILL BE HUNG UP OVER THE NORTHWESTERN PORTION OF THE FORECAST AREA AT 00Z FRI...WITH UPSTREAM LOW CLOUDS LINGERING ACROSS MUCH OF CENTRAL AND SOUTH CENTRAL MN AND WEST CENTRAL WI THROUGH FRIDAY MORNING. NAM/GFS/UKMET MODELS ALL DEPICT SURFACE RIDGING ACROSS THE NORTH CENTRAL CONUS OVER THE WEEKEND...DURING WHICH A DRY FORECAST AND NEAR NORMAL TEMPS HAVE BEEN MAINTAINED. THE ECMWF AND GFS ENSEMBLE SOLUTIONS CONTINUE TO FEATURE THE DEVELOPMENT OF A SURFACE TROUGH OVER THE HIGH PLAINS LATE IN THE WEEKEND...WITH AN ATTENDANT COLD FRONT PASSING ACROSS THE AREA MONDAY NIGHT INTO TUESDAY...DURING WHICH GFS ENSEMBLE PRECIP PROBS ARE ON THE INCREASE. PREVIOUS FORECAST HANDLED THIS WELL...WITH CHANCE POPS INTRODUCED BETWEEN 00Z-12Z TUESDAY. && .AVIATION.../FOR 18Z TAFS/ RAIN AND ISOLATED THUNDER MOVING ACROSS AREA DURING THE AFTERNOON AS UPPER TROUGH/SURFACE BOUNDARY MOVES THROUGH. MVFR CIG/VSBYS WITH THE RAIN AS IT MOVES ACROSS AREA...ENDING BY 20Z AT AXN AND LASTLY AT EAU. CLEARING DURING THE EVENING AND WITH LIGHT WINDS AND LOW LEVEL MOISTURE FOG COULD BE A PROBLEM AGAIN MAINLY AFTER 08Z. MENTION IFR/LIFR CIG/VSBY IN FOG AT STC/RNH/EAU. WILL DEPEND ON HOW FAST SKY BREAKS/CLEAR. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ mn AREA FORECAST DISCUSSION...UPDATED FOR AVIATION AFD NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 658 AM CDT THU AUG 23 2007 .DISCUSSION... EARLY MORNING WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS SHOW A PAIR OF SHORTWAVES TRAVERSING THE UPPER MIDWEST. THESE WAVES ARE AIDING IN CONVECTIVE DEVELOPMENT OVER EASTERN SD/NE. ASSOCIATED ISENTROPIC UPGLIDE ON THE NAM/GFS PROGGED 305K SURFACE SPREADS ACROSS THE FORECAST AREA THIS MORNING...ACCOMPANIED BY A HEALTHY AREA OF 700MB/850MB THETA E ADVECTION. AREA ALSO REMAINS IN THE FAVORABLE ENTRANCE REGION OF THE UPPER LEVEL JET TODAY. FLASH FLOOD WATCH REMAINS IN PLACE FOR THIS MORNING ACROSS SOUTH CENTRAL MN...WHERE PWATS ARE AROUND 2 INCHES. EXPECT EXTENSIVE CLOUD COVER AND PRECIPITATION TO HINDER WARMING TODAY...SO HAVE UNDERCUT GUIDANCE SUBSTANTIALLY...WITH FORECAST HIGHS GENERALLY BETWEEN 70 AND 75. H85 FRONT SHOULD STILL BE HUNG UP OVER THE NORTHWESTERN PORTION OF THE FORECAST AREA AT 00Z FRI...WITH UPSTREAM LOW CLOUDS LINGERING ACROSS MUCH OF CENTRAL AND SOUTH CENTRAL MN AND WEST CENTRAL WI THROUGH FRIDAY MORNING. NAM/GFS/UKMET MODELS ALL DEPICT SURFACE RIDGING ACROSS THE NORTH CENTRAL CONUS OVER THE WEEKEND...DURING WHICH A DRY FORECAST AND NEAR NORMAL TEMPS HAVE BEEN MAINTAINED. THE ECMWF AND GFS ENSEMBLE SOLUTIONS CONTINUE TO FEATURE THE DEVELOPMENT OF A SURFACE TROUGH OVER THE HIGH PLAINS LATE IN THE WEEKEND...WITH AN ATTENDANT COLD FRONT PASSING ACROSS THE AREA MONDAY NIGHT INTO TUESDAY...DURING WHICH GFS ENSEMBLE PRECIP PROBS ARE ON THE INCREASE. PREVIOUS FORECAST HANDLED THIS WELL...WITH CHANCE POPS INTRODUCED BETWEEN 00Z-12Z TUESDAY. && .AVIATION.../FOR 12Z TAFS/ EARLY ON VFR CIG AND VSBYS AS PER DENSE FOG WILL CONTINUE TO AFFECT TAKEOFFS AND ARRIVALS AT ALL TAF SITES SAVE RWF. INCOMING -SHRA AND SLIGHTLY HIGHER SOUTHERLY FLOW ALONG WITH MOISTURE SHIELD DISSOLVING FOG AT THIS LOCATION LIKE ACID. VFR VSBYS WILL BE SEEN AT ALL TAF LOCALES BY 15Z...WITH MVFR TO VFR CIGS EXPECTED INTO LATE THIS AFTERNOON. GFS40 310K ISENTROPIC ANAL PRETTY MUCH NAILING DISTRIBUTION AND INTENSIFY OF -SHRA/ISOLD TSTM ACROSS CWA DURING NEXT 12 HOURS. LI`S INDICATING A MAINLY CONVECTIVE SHOWER EVENT WITH BEST CHANCE FOR TSTMS JUST SOUTH OF EAU BY 18Z. THIS COINCIDES WITH STRONGEST COUPLET PER NAM 250MB DIVERGENCE. DRY AIR WILL FILTER INTO AXN AND RWF BY LATE MORNING...EFFECTIVELY CUTTING OFF PRECIP CHANCES. REMAINDER OF MN TAF SITES WILL FOLLOW THIS TREND BY MID -AFTERNOON AND THE REMAINDER OF WI TAFS BY 02Z. LEFT OVER HIGH CLOUD CONVECTIVE SHIELD WILL FINALLY DISSIPATE ACROSS ENTIRE REGION BY 04Z...PROVIDING EXCELLENT OVERNIGHT FLYING CONDITIONS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...DENSE FOG ADVISORY UNTIL 8 AM CDT THIS MORNING FOR ANOKA-BENTON- BLUE EARTH-BROWN-CARVER-CHIPPEWA-CHISAGO-DAKOTA-DOUGLAS- FARIBAULT-FREEBORN-GOODHUE-HENNEPIN-ISANTI-KANABEC- KANDIYOHI-LAC QUI PARLE-LE SUEUR-MARTIN-MCLEOD-MEEKER-MILLE LACS-MORRISON-NICOLLET-POPE-RAMSEY-REDWOOD-RENVILLE-RICE- SCOTT-SHERBURNE-SIBLEY-STEARNS-STEELE-STEVENS-SWIFT-TODD- WASECA-WASHINGTON-WATONWAN-WRIGHT-YELLOW MEDICINE COUNTIES. FLASH FLOOD WATCH UNTIL NOON CDT TODAY FOR BLUE EARTH-BROWN- FARIBAULT-FREEBORN-GOODHUE-LE SUEUR-MARTIN-NICOLLET-RICE- STEELE-WASECA-WATONWAN COUNTIES. WI...DENSE FOG ADVISORY UNTIL 8 AM CDT THIS MORNING FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX COUNTIES. && $$ LS/JVM mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 1237 PM CDT THU AUG 23 2007 .UPDATE...HAVE CANCELLED FLASH FLOOD WATCH FOR NORTH HALF AS FOCUS HAS SHIFTED SOUTH TO SOUTHEAST BORDER AREA. && .DISCUSSION... SURFACE FRONT HAD PUSHED INTO SOUTHEAST NEBRASKA AT 17Z WITH LINE OF CONVECTION IN EXTREME SOUTHEAST CORNER OF THE STATE. EXTENSIVE LOW CLOUDS NORTH WHICH SHOULD SPREAD SOUTH WITH TIME THIS AFTERNOON. && .PREV DISCUSSION... /ISSUED 417 AM CDT WED AUG 22 2007/ DISCUSSION... DIFFICULT FORECAST ON TAP TODAY THROUGH FRIDAY NIGHT...SPECIFICALLY TIMING/PLACEMENT OF PCPN. WATER VAPOR IMAGERY THIS MORNING SHOWING A NUMBER OF EMBEDDED DISTURBANCES MOVING THROUGH THE MAIN UPPER TROF ACROSS THE NW CONUS...AND INTO THE PLAINS. UPPER DIVG/IMPULSES HAVE HELP KICK OFF LINE OF COMPLEXES FROM SD/WRN NEB/NE CO INVOF A COLD FRONT EXTENDING FROM ABOUT SRN SD TO THE CENTRAL HIGH PLAINS. MEANWHILE...VORT MAX/LLVL JET/MOIST CONVG OVER ERN NEB/WRN IA RESPONSIBLE FOR A LINE OF CONVECTION MOVING ACROSS THE CWA...WITH ANOTHER SEPARATE AREA OF STORMS MOVING NORTHEAST THROUGH NRN KS/SC NEB. GIVEN TRENDS OF REGIONAL 88D LOOP...FAIRLY CONFIDENT CWA SHOULD SEE PCPN ACTIVITY THROUGH MOST OF THE MORNING AND EARLY AFTERNOON. CWA REMAINS IN THE WARM SECTOR TILL FROPA LATER DAY...WITH RUC SHOWING MLCAPES INCREASING THROUGH 12Z-18Z TO 1500 J/KG...SUGGESTING APPROACHING ACTIVITY FROM THE SOUTHWEST SHOULD BE ABLE TO MAINTAIN ITSELF. SURFACE FRONT PUSHES SLOWLY SEWD THROUGH THE CWA TONIGHT AS UPPER TROF AXIS MIGRATES EAST. BOUNDARY EVENTUALLY STALLS FROM ERN IA TO SW KS FRIDAY MORNING. MOISTURE CONTINUES TO POOL ALONG THE BOUNDARY EARLY ON BEFORE THE LLVL JET BEGINS SWINGING FROM S TO SW. WILL THEREFORE FOCUS HIGHER POPS OVER THE SOUTHERN CWA TONIGHT AND FRIDAY WHERE LIFT WILL BE MORE PREVALENT. NEXT DISTURBANCE OF CONCERN BEGINS TO PUSH INTO THE WESTERN DAKOTAS FRIDAY AFTERNOON INDUCING LIFT OVER THE NORTHERN PLAINS. THE NAM IS MORE AGGRESSIVE THAN GFS AND LAYS PATCH OF QPF INVOF THE NRN CWA FRIDAY EVENING...SO WILL ADD TOKEN POPS JUST IN CASE. FINALLY...MILD AND DRY SATURDAY AND SUNDAY. AVIATION... WIDESPREAD CONVECTION FM NORTHEAST NEBRASKA INTO WCNTRL IA SHOULD CONT TILL AROUND 12Z WITH OTHER SHOWERS/ISOLD TSTMS EXPECTED TO MOVE INTO AND ACROSS MUCH OF ERN NEBRASKA THIS MORNING. ALTHOUGH A LULL IN THE ACTIVITY IS POSSIBLE LATER THIS MORNING...AN INCREASE IN CONVECTION IS LIKELY LATER THIS AFTN/EARLY TNGT AS A FRONT PUSHES ACROSS THE AREA. THE WIDESPREAD RAIN HAS LEFT LOW CLOUDS SCT ACROSS THE AREA WITH CIGS MOSTLY IN THE 1000-2000 FOOT RANGE BUT OCNLY DROPPING INTO THE IFR CATEGORY. APPEARS THERE WL BE ENOUGH CLOUD COVER/MIXING TO KEEP WDSPRD VSBY RESTRICTIONS FROM OCCURRING THIS MORNING...OUTSIDE OF PCPN AREAS ANYWAY. HOWEVER...SOME ISOLD 3SM BR IS POSSIBLE FOR SVRL HOURS THIS MORNING. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ FOBERT ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 417 AM CDT WED AUG 22 2007 .DISCUSSION... DIFFICULT FORECAST ON TAP TODAY THROUGH FRIDAY NIGHT...SPECIFICALLY TIMING/PLACEMENT OF PCPN. WATER VAPOR IMAGERY THIS MORNING SHOWING A NUMBER OF EMBEDDED DISTURBANCES MOVING THROUGH THE MAIN UPPER TROF ACROSS THE NW CONUS...AND INTO THE PLAINS. UPPER DIVG/IMPULSES HAVE HELP KICK OFF LINE OF COMPLEXES FROM SD/WRN NEB/NE CO INVOF A COLD FRONT EXTENDING FROM ABOUT SRN SD TO THE CENTRAL HIGH PLAINS. MEANWHILE...VORT MAX/LLVL JET/MOIST CONVG OVER ERN NEB/WRN IA RESPONSIBLE FOR A LINE OF CONVECTION MOVING ACROSS THE CWA...WITH ANOTHER SEPARATE AREA OF STORMS MOVING NORTHEAST THROUGH NRN KS/SC NEB. GIVEN TRENDS OF REGIONAL 88D LOOP...FAIRLY CONFIDENT CWA SHOULD SEE PCPN ACTIVITY THROUGH MOST OF THE MORNING AND EARLY AFTERNOON. CWA REMAINS IN THE WARM SECTOR TILL FROPA LATER DAY...WITH RUC SHOWING MLCAPES INCREASING THROUGH 12Z-18Z TO 1500 J/KG...SUGGESTING APPROACHING ACTIVITY FROM THE SOUTHWEST SHOULD BE ABLE TO MAINTAIN ITSELF. SURFACE FRONT PUSHES SLOWLY SEWD THROUGH THE CWA TONIGHT AS UPPER TROF AXIS MIGRATES EAST. BOUNDARY EVENTUALLY STALLS FROM ERN IA TO SW KS FRIDAY MORNING. MOISTURE CONTINUES TO POOL ALONG THE BOUNDARY EARLY ON BEFORE THE LLVL JET BEGINS SWINGING FROM S TO SW. WILL THEREFORE FOCUS HIGHER POPS OVER THE SOUTHERN CWA TONIGHT AND FRIDAY WHERE LIFT WILL BE MORE PREVALENT. NEXT DISTURBANCE OF CONCERN BEGINS TO PUSH INTO THE WESTERN DAKOTAS FRIDAY AFTERNOON INDUCING LIFT OVER THE NORTHERN PLAINS. THE NAM IS MORE AGGRESSIVE THAN GFS AND LAYS PATCH OF QPF INVOF THE NRN CWA FRIDAY EVENING...SO WILL ADD TOKEN POPS JUST IN CASE. FINALLY...MILD AND DRY SATURDAY AND SUNDAY. && .AVIATION... WIDESPREAD CONVECTION FM NORTHEAST NEBRASKA INTO WCNTRL IA SHOULD CONT TILL AROUND 12Z WITH OTHER SHOWERS/ISOLD TSTMS EXPECTED TO MOVE INTO AND ACROSS MUCH OF ERN NEBRASKA THIS MORNING. ALTHOUGH A LULL IN THE ACTIVITY IS POSSIBLE LATER THIS MORNING...AN INCREASE IN CONVECTION IS LIKELY LATER THIS AFTN/EARLY TNGT AS A FRONT PUSHES ACROSS THE AREA. THE WIDESPREAD RAIN HAS LEFT LOW CLOUDS SCT ACROSS THE AREA WITH CIGS MOSTLY IN THE 1000-2000 FOOT RANGE BUT OCNLY DROPPING INTO THE IFR CATEGORY. APPEARS THERE WL BE ENOUGH CLOUD COVER/MIXING TO KEEP WDSPRD VSBY RESTRICTIONS FROM OCCURRING THIS MORNING...OUTSIDE OF PCPN AREAS ANYWAY. HOWEVER...SOME ISOLD 3SM BR IS POSSIBLE FOR SVRL HOURS THIS MORNING. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING NEZ011-012-015>018-030>034-042>045. IA...FLASH FLOOD WATCH IN EFFECT THROUGH THIS EVENING IAZ043-055-056. && $$ DEE/CHERMOK ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 134 AM EDT FRI AUG 24 2007 .SYNOPSIS... WARM FRONT ACROSS NORTHERN OHIO AND LAKE ERIE WILL LIFT NORTH OVERNIGHT. A WARM MOIST FLOW WILL CONTINUE THROUGH FRIDAY NIGHT. A COLD FRONT WILL MOVE ACROSS THE AREA ON SATURDAY. IT WILL BE FOLLOWED BY HIGH PRESSURE MOVING INTO THE AREA SUNDAY. THE HIGH WILL LINGER OVER THE AREA INTO EARLY NEXT WEEK...WITH THE NEXT COLD FRONT FORECAST TO MOVE THROUGH NEXT THURSDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... A BIT OF A DILEMMA FOR NW OHIO. FIRST ROUND OF STORMS HAS SKIRTED BY TO THE NORTH. THE NEXT ROUND OF STORMS ARE NOT DUE UNTIL ABOUT MIDNIGHT IN THE TOLEDO AREA. SEVERE THUNDERTORM WATCH 642 WILL EXPIRE BEFORE THS STORMS ARRIVE. BEING AS THERE WILL BE NO ACTIVITY BY 11 PM...HAVE CANCELLED SEVERE TSTORM BOX 642 FOR MY 4 COUNTIES IN NW OH. TSTORM COMPLEX ROLLING ACROSS NW INDIANA IS WEAKENING BUT LOW LEVEL JET PROGGED TO SHIFT EAST JUST ENOUGH THAT I AM NOT CONVINCED THAT THE STORMS WILL END. THE SEVERE ASPECT OF THE STORMS WILL END BUT THERE IS STILL THE POTENTIAL FOR HEAVY RAIN IF TRAINING DEVELOPS AS THE LINE OF STORMS GETS STRUNG OUT WEST TO EAST. THIS HAS BEEN HAPPENING ALL WEEK AND THERE IS A BETTER LOW LEVEL JET TONIGHT BUT LESS DIFFERENTIAL ADVECTION SINCE WE ARE UNDER THE UPPER RIDGE NOW. MODELS DO NOT INDICATE MUCH RAIN. NONE OF THEIR SREF MEMBERS SHOW ANY SGNIFICANT RAIN GETTING INTO NW OHIO. MODELS HAVE NOT HANDLED PREVIOUS EVENTS WELL THOUGH. DO NOT ANTICPATE THE COPIUS AMOUNTS OF RAIN WE SAW EARLIER IN THE WEEK BUT WE CANNOT HANDLE ANY SIGNIFICANT RAIN ACROSS NW OHIO. THINK THE RAIN WILL STAY NORTH OF BUCYRUS AND UPPER SANDUSKY BUT MAY GET CLOSE TO FINDLAY. BETTER CHANCE FARTHER NORTH TOWARD TOLEDO AND PORT CLINTON. WILL ISSUE FLOOD WATCH THROUGH 4 PM FRIDAY. ELSEWHERE...THE SMATTERING OF STORMS ACROSS NE OH/NW PA IS TAPERING OFF. RUC SHOWS QUITE A BIT OF INSTABILITY PERSISTING ACROSS NE OH/NW PA OVERNIGHT AND WILL KEEP A CHANCE OF SHOWERS/TSTORMS IN FCST. SLIGHT CHANCE FARTHER SOUTH FROM MOUNT VERNON TO WOOSTER AND YTOWN. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/... ENTIRE AREA REMAINS IN WARM MOIST AIRMASS UNTIL FRONT MOVES THROUGH SATURDAY MORNING OR EARLY AFTERNOON. MAV MOS GUIDANCE POPS LOW FRIDAY/FRIDAY NIGHT WITH MOST AREA BELOW THRESHOLD OR SLIGHT CHANCE TOMORROW. BUT WILL CONTINUE WITH AT LEAST CHANCE POPS FOR BOTH OF THE PERIODS. BEST CHANCE FOR TSTM TOMORROW SHOULD COME FROM ANY BOUNDARIES THAT MAY MOVE INTO THE AREA FROM MCS PASSING NORTH OF THE AREA. THEN SCATTERED SHOWERS AND THUNDERSTORMS SATURDAY WITH FRONT MOVING THROUGH. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... HIGH PRESSURE MOVING INTO THE AREA ON SUNDAY SHOULD PROVIDE A FEW DAYS OF DRY AND SEASONABLY WARM WEATHER. THE DRY WEATHER SHOULD LAST INTO TUESDAY NIGHT...THEN COLD FRONT APPROACHES WEDNESDAY MOVING THROUGH THURSDAY. GFS OPERATIONAL RUNS APPEAR TOO FAST WITH THIS FRONT. HPC MANUAL PROGS FOLLOWING SLOWER GFS ENSEMBLES MEAN AND ECMWF. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... TRAINING CLUSTERS OF THUNDERSTORMS WILL CONTINUE TO MOVE EAST FROM ILLINOIS INTO NORTHERN OHIO...LAKE ERIE...AND NORTHWEST PENNSYLVANIA THROUGH THE MORNING HOURS. SOME SCATTERED CONVECTION MAY DEVELOP SOUTH OF THE LAKE SHORE AREAS BUT I WILL LEAVE IT OUT OF THOSE TAFS FOR NOW SINCE IT MAY BE SO WIDELY SCATTERED AND THEY MAY QUICKLY DISSIPATE AFTER FORMATION. OTHER PROBLEM TO DEAL WITH IS REDUCED VISIBILITIES AT ERIE AND YOUNGSTOWN AS HAZE AND MIST OCCUR. DROPPED VISIBILITIES THIS MORNING ACCORDINGLY. WINDS WILL CONTINUE FROM THE SOUTH THROUGH THE 24 HOUR FORECAST PERIOD AT AROUND 10 KNOTS. OUTLOOK SATURDAY THROUGH MONDAY...COLD FRONT FORECAST TO MOVE THROUGH OHIO AND PENNSYLVANIA ON SATURDAY. SHOWERS AND THUNDERSTORMS WITH LOCALLY REDUCED CIGS AND VSBYS CAN BE EXPECTED ON SATURDAY WITH SIGNIFICANT IMPROVEMENT TO VFR CONDS BY SUNDAY. GENERALLY FAVORABLE CONDITIONS WILL REMAIN THROUGH EARLY NEXT WEEK. && .MARINE... A NEARLY STATIONARY WARM FRONT ACROSS NORTHERN OHIO WILL REMAIN IN THE VICINITY OF THE LAKE TONIGHT. SHOWERS AND THUNDERSTORMS HAVE BEEN DEVELOPING IN PLACES ALONG THIS FRONT AND THEREFORE THE CHANCE FOR SHRA/TS REMAINS IN THE FORECAST. WINDS WILL PRIMARILY BE SSW PICKING UP TOWARD FRIDAY MORNING AS A WAVE OF LOW PRESSURE IS FORECAST TO MOVE ALONG THE PRIMARY COLD FRONT ACROSS THE CENTRAL LAKES...INCREASING THE GRADIENT. SOUTHERLY COMPONENT WINDS WILL CONTINUE INTO SATURDAY WHEN THE COLD FRONT IS EXPECTED TO MOVE ACROSS LAKE ERIE. SMALL CRAFT CONDITIONS POSSIBLE ON SAT EAST HALF...BUT BY SUNDAY WIND/WAVES SHOULD BE DIMINISHING AS HIGH PRESSURE BUILDS IN. SOUTHERLY FLOW RETURNS EARLY NEXT WEEK AS THE HIGH WILL BE EAST OF THE LAKES. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...FLOOD WATCH THROUGH THIS AFTERNOON FOR OHZ003-006>009-017>019. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...RANDEL NEAR TERM...KOSARIK SHORT TERM...RANDEL LONG TERM...RANDEL AVIATION...LOMBARDY MARINE...OUDEMAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1115 AM EDT THU AUG 23 2007 .SYNOPSIS... AN UPPER RIDGE WILL REMAIN OVER THE SOUTHEAST THROUGH THE END OF THE WEEK...BEFORE A COLD FRONT APPROACHES THE WESTERN CAROLINAS LATE IN THE WEEKEND. THE FRONT WILL BECOME STATIONARY OVER THE REGION AND SLOWLY DISSIPATE EARLY NEXT WEEK AS THE UPPER RIDGE BUILDS BACK OVER THE REGION ONCE AGAIN. && .NEAR TERM /THROUGH TONIGHT/... SKIES ARE CLEARING OUT OVER MOST OF THE CWFA AS OF 11 AM...WITH SOME CU BEGINNING TO DEVELOP OVER SOME THE WESTERN MTNS AND ACROSS THE UPSTATE. THE STALLED BOUNDARY THAT IS BISECTING NC ALONG I-77 MAY HELP INITIATE SOME CONVECTION ACROSS THE I-77 CORRIDOR. ALSO...A SLIGHT UPSLOPE COMPONENT TO THE LOW LEVEL WIND FLOW...SHOULD HELP CONVECTION DEVELOP OVER THE MTNS AND FOOTHILLS BY MID AFTN. MADE MINOR ADJUSTMENTS TO POP...MAINLY INCREASING TO SOLID CHC ACROSS THE I-77 CORRIDOR AND SOUTHERN UPSTATE COUNTIES...WHERE DIFFERENTIAL HEATING BOUNDARY IS LOCATED. BASED ON 12Z GSO SOUNDING AND RUC/NAM12 DATA...SEVERE THREAT THIS AFTN LOOKS UNCHANGED FROM EARLIER THINKING. SO FEEL HWOGSP IS IN GOOD SHAPE. OTHERWISE...TEMP/DEWPOINTS/WINDS ALL LOOK ON TRACK FOR THE REST OF TODAY. MAX TEMPS EXPECTED TO BE IN THE LOWER 90S ACROSS NE ZONES...TO MID 90S ACROSS THE UPSTATE. SHRA AND TSRA WILL GRADUALLY DIMINISH THIS EVENING AND DEBRIS CLOUDS SHOULD LINGER UNTIL MIDNIGHT. OTHERWISE...TONIGHT SHOULD BE FAIRLY QUIET AND DRY. LOW TEMPERATURES FRI AM SHOULD FALL IN THE LOW TO MID 70S BY SUNRISE. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... AXIS OF THE H5 RIDGE WILL EXTEND NE TO SW ACROSS THE FORECAST AREA ON FRIDAY. SO DEEP LAYER FORCING WILL BE ABSENT. HOWEVER...LLVL UPSLOPE FLOW WILL AGAIN BE PRESENT WITH GOOD CONVERGENCE ACROSS THE HIGH TERRAIN. BOTH THE NAM AND GFS HAVE A MODERATE AMOUNT OF CAPE OVER THE MOUNTAINS AND WESTERN FOOTHILLS DURING THE AFTERNOON...WITH LESS INSTABILITY OVER OVER THE PIEDMONT. PLAN TO CARRY 30/40 POPS MTNS AND FOOTHILLS AND 20 POPS FARTHER EAST. LLVL THICKNESSES ARE UP AROUND 1340 ON THE NAM AND 1335 ON THE GFS. THIS IS CERTAINLY GOOD FOR 90S IN THE MOUNTAINS AND FOOTHILLS. AND WITH HIGHER DEWPOINTS...IT WILL STILL ABOUT AS BAD AS IT DID ON THOSE DAYS WE HIT TRIPLE DIGIT HIGHS OF LATE. A NORTHERN STREAM LONG WAVE TROF DIMPLES THE WESTERLIES ON SATURDAY. IT LOOKS WEAKER THAN IT DID ON PREVIOUS RUNS...WHICH HAS BEEN PAR FOR THE COURSE FOR THIS SUMMER. THE H5 RIDGE AXIS...DESPITE WEAKENING A LITTLE...WILL STILL EXTEND FROM NE TO SW ACROSS THE MOUNTAINS. SO ONCE AGAIN THERE WILL BE LITTLE IN THE WAY OF UPPER LEVEL FORCING. THE LLVL FLOW WILL BE EVEN WEAKER ON SATURDAY...BUT I SUSPECT WINDS IN THE 1000-850 LAYER WILL TAKE ON A SLIGHTLY STRONGER WESTERLY COMPONENT AHEAD OF THE LONG WAVE OVER ERN TN...WHICH SHOULD CONTINUE GOOD CONVERGENCE ACROSS THE MOUNTAINS. THE NAM DOES THIS AND DEVELOPS QUITE A BIT OF CONVECTION OVER THE MOUNTAINS AND ACROSS THE LEE AS A RESULT...AND I/LL KEEP SOLID CHANCE POPS OVER THE HIGH TERRAIN AND FOOTHILLS TO ACCOUNT FOR THIS. IF THE NAMS/S 1450+ METER THICKNESS VERIFY ON SAT...WE MAY BE LOOKING AT HIGHS APPROACHING 100 AGAIN IN THE LEE. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... LATEST GFS TAKES A SURFACE FRONT ABOUT AS FAR EAST AS THE NC MTNS SUNDAY AFTERNOON. WITH DOWNSLOPE FLOW AHEAD OF THE FRONT...MAX TEMPS SHOULD ONCE AGAIN BE WELL IN THE 90S. AFTER COLLABORATING WITH NEIGHBORING OFFICES...I RAISED MAX TEMPS A FEW DEGREES. I KEPT IN SCATTERED SHOWERS AND THUNDERSTORMS AS THERE SHOULD BE SOME CONVECTION WITH THE FRONT AND A WEAK H5 SHORT WAVE...BUT I WOULDN/T EXPECT COVERAGE WL BE ANY GREATER THAN IN THE TWO PRECEDING DAYS. HEIGHTS RISE AGAIN NEXT WEEK...AND I NOTICE THAT THE GFS LAYER RH/S IN THIS RUN ARE LOWER THAN THEY HAVE BEEN IN PAST RUNS IN THE MON-WED TIME RANGE. I DIDN/T CHANGE ANYTHING BEYOND SUNDAY WITH THIS PACKAGE...BUT I WOULD LOOK FOR A DRIER AND WARMER TREND IN THE FORECAST AS THE RIDGE LOOKS AS IF IT WILL ONCE AGAIN BE STRONGER... DRIER AND FARTHER WEST THAN INITIALLY EXPECTED. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... STILL SOME MVFR CIGS AT HKY...BUT LOOK TO MIX OUT TO 6000 OR MORE FT BY 18Z. OTHERWISE...VFR THIS AFTN WITH SCT TS ACROSS THE REGION (SEE BELOW). THIS AFTERNOON...THE CENTER OF THE H5 RIDGE PUSHES WEST...ALLOWING A WEAK VORT TO SLIDE SOUTH ACROSS THE CENTRAL CAROLINAS. MODERATE INSTABILITY...WEAK LIFT...AND INVERTED PIEDMONT TROF SHOULD YIELD SOME DEEP CONVECTION. AT THIS TIME...THE GREATEST COVERAGE IS EXPECTED ALONG THE I-77 CORRIDOR AND THE HIGHER TERRAIN AFTER 18Z. I WILL INCLUDE A MENTION OF VCSH OR VCTS AT ALL TERMINALS THIS AFTERNOON. I WILL TEMPO TSRA FOR ALL TERMINALS (SAVE KCLT) FROM 20-02. NORTHEAST TO EAST WIND SHOULD CONTINUE ACROSS THE TERMINALS THROUGH THE PERIOD...REMAINING LESS THAN 10 KTS. ISOLATED TO WIDELY SCATTERED AFTERNOON CONVECTION AND LIGHT MORNING FOG WILL BE POSSIBLE THROUGH THE REMAINDER OF THE WEEK...ESPECIALLY IN THE MTNS. COVERAGE OF CONVECTION MAY INCREASE OVER THE WEEKEND... AS A FRONT APPROACHES FROM THE NORTHWEST. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...MCAVOY NEAR TERM...ARK/NED SHORT TERM...MCAVOY LONG TERM...ARK/MCAVOY AVIATION...ARK/JDL/NED sc AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 938 PM CDT WED AUG 22 2007 .DISCUSSION... LATE AFTERNOON SHRA/TSRA COMPLEX ACROSS SOUTHERN CWA CONTINUES TO PUSH SOUTHEAST INTO BETTER MOISTURE/INSTABILITY ACROSS SOUTHEAST NEBRASKA AND SOUTHERN IOWA THIS EVENING. THIS GIVING MUCH OF OUR FORECAST AREA A BREAK FOR THE EVENING...AND UPDATED TO DRAMATICALLY REDUCE OR PULL EVENING PRECIP CHANCES MOST AREAS. STILL HAD SOME ANVIL PRECIP LINGERING ACROSS THE FAR SOUTHEAST...SO MAINTAINED SOME HIGHER POPS THERE...THOUGH PULLED BACK QPF QUITE A BIT PRIOR TO 06Z. QUESTION NOW IS HOW WELL PRECIP NOW ACROSS THE WESTERN HIGH PLAINS WILL HOLD TOGETHER AS IT TRANSLATES EAST AHEAD OF THE UPPER WAVE. 00Z NAM CONTINUES TO SHOW IMPRESSIVE DEEP LAYER THETA-E ADVECTION SPREADING BACK ACROSS THE CWA AFTER 06Z...WITH STRONG 850MB MOISTURE TRANSPORT AND INCREASING ELEVATED INSTABILITY INTO AREAS SOUTH OF I-90 BY 12Z. THINK THIS ALONG WITH THE UPPER SUPPORT WILL AID IN MAINTAINING TSRA INTO OUR FORECAST AREA LATER TONIGHT...MAINLY ALONG AND WEST OF THE JAMES RIVER THROUGH 09Z...THEN SLIDING THROUGH THE I-29 CORRIDOR INTO NORTHWEST IOWA AND SOUTHWEST MINNESOTA AFTER 09Z. SIMILAR RETURN OF MOISTURE AND ELEVATED INSTABILITY SEEN ON 00Z RUC SO WILL HOLD ONTO GOING FLASH FLOOD WATCH. UPDATES HAVE BEEN SENT. && .AVIATION... NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP AFTER MIDNIGHT TONIGHT OVER MUCH OF ERN SD AND EVENTUALLY ACROSS SOUTHERN MINNESOTA. MVFR CEILINGS ARE LIKELY ONCE SHOWERS AND STORMS DEVELOP...HOWEVER WITH SOME ISOLATED THUNDERSTORMS CEILINGS MAY DROP AS LOW AS 1500 FT. SHOWERS AND THUNDERSTORMS EVENTUALLY EXIT ERN SD LATE THU MORNING. IFR CEILING ARE POSSIBLE AT LOCAL TAF SITE MUCH OF THE DAY THU AS ABUNDANT AMOUNTS OF LOW LEVEL MOISTURE REMAIN OVER THE AREA. && .PREV DISCUSSION... WIDESPREAD SHRA/TS BEGINNING TO NUDGE NEWD AGAIN INTO THE MO RIVER VALLEY AREAS...AND ALSO LINGERING FURTHER EWD IN THE STORM LAKE AND SPENCER IA AREAS. EXPECT THIS TREND TO CONTINUE THROUGH THE LATE AFTERNOON AS A SECOND AREA OF SHRA/TS IN N CENTRAL NEB LIFTS E AND SLIGHTLY NEWD. ATTM...DO NOT SPREAD WIDESPREAD HVY RAIN IN NW IA LATE THIS AFTN AND EARLY EVENING...BUT THERE COULD BE SOME FURTHER WEST AROUND BON HOMME AND YANKTON COUNTIES...AND POINTS IMMEDIATELY ADJACENT TO THOSE AREAS. ONGOING NEBRASKA CONVECTION HAS LIKELY SUPPRESSED LOW LEVEL BOUNDARY FAR ENOUGH SOUTH THAT THE EXTREME UPDRAFTS WL LIMIT THE SVR WX THREAT THIS EVENING TO S OF THE FSD FA...POSSIBLY SOME MARGINAL SEVERE IN OUR FAR S. THE AREA TO WATCH FOR WILL BE WY/WESTERN SD AS AN MCS SHOULD DEVELOP AHEAD OF A STRONG UPPER LEVEL WAVE...THEN PROGRESS EAST. THIS WAVE IS ALREADY CLEARLY EVIDENT IN WRN WY THIS AFTN. THE QUESTION BECOMES HOW FAR EAST THIS WAVE WILL PROGRESS ON WHAT WILL LIKELY BE THE 700-750MB BOUNDARY/FORCING AS NE/IA CONVECTION DOMINATES. LLJ FORCING REALLY PEGS FLASH FLOOD WATCH AREA LATE TONIGHT...AS ANOTHER MID LEVEL WAVE LIFTS ENE WHICH IS CURRENTLY IN ERN CO/WRN KS. WILL DECREASE POPS SOME TONIGHT OVER SOUTHWEST MINNESOTA UNTIL LATE. AFTER 5 TO 10 INCHES OF RAIN OVER PARTS OF NW IA AND SW MN OVER THE LAST 48 HOURS...WILL CONTINUE FLASH FLOOD WATCH. ON THUR...DECIDED TO EXTEND FFA UNTIL ABOUT 11 AM WITH THE WY WAVE HAVING MOVED INTO CENTRAL/WRN SD THUR MORNING. THIS WAVE INTERACTS WITH THE DEPARTING WAVE WHICH IS CURRENTLY IN ERN CO/WRN KS TO PRODUCE SOME MORE POSSIBLE LOCALLY HVY RAIN IN OUR ERN FA BEFORE IT DEPARTS BY NOON. THE H7 FRONT IS EXTREMELY STRONG THUR MORNING AS IT INCHES INTO THIS FA FOR THIS TIME OF YEAR. TAILED BACK SOME HIGHER QPF AMOUNTS TO OUR NWRN FA THUR MORNING TOWARD HURON IN A SUBTLE FEED WITH THE SD WAVE...BUT SOME OVERALL DRIER AIR LOOKS TO BE UNDERCUTTING ALL OF THIS IN OUR FAR SWRN FA THUR MORNING AND EWD TOWARD YANKTON. THEREFORE THE LOWEST POPS ARE WARRANTED IN GREGORY CO EARLY THUR. THUR AFTN...THE SFC BOUNDARY FINALLY BEGINS TO PUSH SWD DEEPER IN NEB AND IA WHICH WL PRODUCE ONLY LIGHTER TS/SHRA IN OUR SERN HALF JUST AHEAD OF THE MID LVL FRONT. DISCREPANCY EXISTS BETWEEN THE NAM AND GFS THUR NIGHT...AS THE GFS BRINGS ONE MORE STRONG WAVE ENE THRU THE CENTRAL PLAINS. THIS WAVE SCRAPES THE SE SECTION OF OUR FA...WHEREAS THE NAM HAS IT FURTHER S. WITH THE NAM TENDENCY TO PUSH BOUNDARIES A BIT TOO FAR SWD...OPTED TO COMPROMISE BETWEEN THE TWO ATTM...SIMILAR TO SREF OUTPUT AND KEEP SOME SCT POPS GOING FM SIOUX CITY TO STORM LAKE...BUT ELIMINATING THE POPS RAPIDLY HEADING N OF THERE. MORE DISCREPANCY IS NOTED ON FRIDAY. BUT IN GENERAL...BROAD MID LVL TROFFINESS HANGS AROUND LINGERING SOME FAIRLY DEEP MOISTURE AROUND IN THIS AREA. MOST OF THE WAVE INTERACTION IS IN CENTRAL AND WRN SD ON FRIDAY WHERE THE RETURN LLJ IS...HOWEVER ATTM OPTED TO LEAVE OUR FAR WRN FA DRY BUT JUST UNDER ISOLD POPS. THIS BROAD WAVE DEPARTS FRI NIGHT AND AGAIN...WE WILL HAVE TO KEEP AN EYE ON FURTURE SHIFTS OF ANY LIGHT SHRA POTENTIAL MOVG EWD WITH IT. FOR TEMPS...COOLED OFF READINGS WITH THE CLOUD COVER ON THU AND FRI COUPLED WITH THE FAIRLY COOL NRN PLAINS ANTICYCLONE DOMINATING THIS AREA WITH A N TO NE FETCH OF SFC AIR. SATURDAY SHOULD BE CLOSER TO NORMAL AND DID NOT ALTER OUR GOING FCST TEMPS FOR THAT DAY AS THE SFC WINDS COME AROUND TO THE SE. IN THE EXTENDED...CONTINUED TO FOLLOW THE SLOWER GEM/ECMWF WITH THE NEXT MAJOR FRONTAL PASSAGE WHICH OCCURS IN THIS FA TUE AND TUE NIGHT. GUIDANCES ARE BEGINNING TO WARM UP READINGS IN THE SUN AND MON TIMEFRAME AHEAD OF THIS FRONT SIMILAR TO WHAT WE ALREADY HAD GOING...SO ALTERED MAX/MINS VERY LITTLE. THIS FRONT HAS SOME GOOD PUSH BEHIND IT. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...FLASH FLOOD WATCH THROUGH 11 AM THURSDAY FOR IAZ002-003-012>014-020>022-031-032. MN...FLASH FLOOD WATCH THROUGH 11 AM THURSDAY FOR MNZ080-081-089-090. NE...FLASH FLOOD WATCH THROUGH 11 AM THURSDAY FOR NEZ013-014. SD...FLASH FLOOD WATCH THROUGH 11 AM THURSDAY FOR SDZ068>071. && $$ JH/SL sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 909 PM CDT FRI AUG 24 2007 .DISCUSSION...500MB RIDGE ACROSS THE SOUTHEAST UNITED STATES CONTINUES TO PROVIDE SUBSIDENCE ACROSS EAST TEXAS TONIGHT. NOT MUCH IN THE WAY OF CONVECTION ACROSS SOUTH TX AND THE NORTHWEST GULF OF MEXICO THIS EVENING AS A RESULT. WATER VAPOR SATELLITE IMAGES AND RUC80 200MB WIND STREAMLINE ANALYSIS INDICATED A TUTT LOW OVER THE EASTERN GULF OF MEXICO DRIFTING WESTWARD. PRECIPITABLE WATER VALUES HAVE INCREASED ACROSS THE AREA SINCE YESTERDAY. WILL LIKELY SEE A SLIGHT INCREASE IN RAIN CHANCES SATURDAY AS THE UPPER LEVEL LOW OVER THE GULF APPROACHES THE CWA FROM THE EAST. WILL UPDATE GRIDS/ZONES TO REMOVE MENTION OF EVENING SHOWERS AND THUNDERSTORMS. OTHERWISE...CURRENT FORECAST LOOKS GOOD SO NO CHANGES ARE EXPECTED. 32 && .PREV DISCUSSION... /ISSUED 645 PM CDT FRI AUG 24 2007/ AVIATION...SETX TAF LOCATIONS WILL REMAIN ESSENTIALY VFR FOR THE NEXT 24 HOURS. RURAL TERMINALS MAY EXPERIENCE SOME PATCHY EARLY MORNING MIFG...BUT DO NOT ANTICIPATE IT TO BE A WIDESPREAD HAZARD. TAF LOCATIONS ALONG COASTAL COUNTIES MAY EXPERIENCE BRIEF MVFR CONDITIONS EARLY/MID-AFTERNOON WITH PASSAGE OF SEA BREEZE. USED PROB30 GROUP TO ALLOW FOR SEABREEZE ACTIVITY IN LBX...SGR...HOU...AND IAH TAFS. ANY ASSOCIATED SHOWER OR THUNDERSTORM ACTIVITY SHOULD BE SHORT LIVED. 44 PREV DISCUSSION.../ISSUED 330 PM CDT FRI AUG 24 2007/ KEEPING AN EYE ON THE SMALL CONVECTIVE COMPLEX CURRENTLY MOVING ACROSS LCH THIS AFTN. WHILE THE STORMS HAVE DECREASED IN INTEN- SITY SOMEWHAT THESE LAST COUPLE OF HOURS...STILL CONCERNED WITH ITS PERSISTENT WWD TRACK AND THE AMOUNT OF DEVELOPMENT OF TSRAS OVER THE COASTAL WATERS. THE DRIER AIR THAT HAS HELD US IN GOOD STEAD TODAY MAY NOT BE ENOUGH TO KEEP THE WOLVES AT BAY FOR THE EARLY EVENING HOURS. THIS DEEPER TROPICAL MOISTURE LOOKS FAIRLY IMMINENT. HAVE ADDED THE MENTION OF ISOLATED TSRA FOR THE SHORT TERM. OTHERWISE PROGS ARE KEEPING WITH THE GENERAL SCRIPT OF IN- CREASING POPS THIS WEEKEND AS THIS FIRST SURGE OF MOISTURE GOES ASHORE. THE INITIAL 1.8"-1.9" PWS SHOULD BE SUFFICIENT FOR SOME SCT TSRA WITH THE SEABREEZE/AFTN HEATING AGAIN ON SAT/SUN...BUT MODELS ARE FOCUSING ON MONDAY AS THE TUTT LOW APPROACHES THE TX BEACHES. PWS FCST TO SPIKE AOA 2.3" AS THE RIDGE ALOFT BEGINS A SLOW BREAKDOWN. THE MOISTURE/UNSETTLED CONDITIONS SHOULD LINGER THROUGH MID WEEK OR SO. AS FOR THE COLD FRONT NEXT WEEKEND THAT THE GFS HAS BEEN TEASING US WITH...THE 12Z RUNS HAVE BACKED OFF WITH REGARD TO A FROPA FOR E/SE TX. HOWEVER THE LARGE SCALE PAT- TERN STILL INDICATING A BREAK IN THE RIDGE AS A LONGWAVE TROUGH MOVES ACROSS THE GREAT LAKES. SO...WILL OPT TO KEEP OUR FINGERS CROSSED AS VISIONS OF LOWER DEWPOINTS DANCE THROUGH OUR HEADS. PREV MARINE.../ISSUED 330 PM CDT FRI AUG 24 2007/ SWELLS HAVE SUBSIDED AND SEAS DOWN TO 3 TO 4 FT ACROSS THE WATERS THIS AFTN. TYPICAL LIGHT ONSHORE FLOW/LATE SUMMER CONDITIONS THROUGH THE FCST PERIOD. WINDS WILL BE STRONGEST DURING THE NIGHT (10 TO 15 KTS) AND WEAKEST IN THE AFTNS (5 TO 10 KTS). SEAS MAINLY 2 TO 3 FT. WINDS COULD BE A BIT STRONGER AND MORE EASTERLY SUNDAY/MONDAY AS A WEAK TROPICAL WAVE MOVES INTO WRN GULF. 35 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 75 95 76 95 76 / 10 20 20 30 30 HOUSTON (IAH) 76 94 76 94 76 / 10 30 30 40 40 GALVESTON (GLS) 81 90 82 90 82 / 10 30 30 40 40 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ DISCUSSION...32 AVIATION/MARINE...44 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 322 PM CDT THU AUG 23 2007 SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT MAIN FORECAST CONCERNS ARE PRECIPITATION TONIGHT INTO FRIDAY. LATEST WATER VAPOR SATELLITE IMAGERY INDICATING A SERIES OF UPPER LEVEL SHORTWAVE TROUGHS EMBEDDED IN WEST TO SOUTHWESTERLY FLOW ALOFT. FIRST SHORTWAVE TROUGH OVER EASTERN NEBRASKA AND WESTERN IOWA AND A SECOND SHORTWAVE TROUGH OVER THE ROCKY MOUNTAINS. LATEST KARX RADAR INDICATING SHOWERS OVER FORECAST AREA. THIS IS IN RESPONSE TO STRONG MOISTURE TRANSPORT AND CONVERGENCE AT 850- 700MB LAYER OUT AHEAD OF FIRST SHORTWAVE TROUGH PER THE LATEST RUC. 12Z THURSDAY GFS AND NAM INITIALIZE OVERALL WEST TO SOUTHWESTERLY FLOW ALOFT WELL PER LATEST WATER VAPOR SATELLITE IMAGERY. BOTH MODELS INITIALIZED SHORTWAVE TROUGH OVER EASTERN NEBRASKA AND WESTERN IOWA WELL. BOTH MODELS CONTINUE TO HAVE TIMING AND PLACEMENT ISSUES WITH SURFACE FEATURES...MOISTURE TRANSPORT AND CONVERGENCE ASSOCIATED WITH SHORTWAVE TROUGHS MOVING INTO THE GREAT LAKES REGION TONIGHT INTO FRIDAY. 12Z THURSDAY NAM IS SLOWER AND FARTHER SOUTH AND EAST THAN GFS. WILL TAKE A MODEL BLEND FOR TONIGHT INTO FRIDAY. BOTH MODELS IN GOOD AGREEMENT OF BUILDING SURFACE RIDGE INTO THE UPPER MIDWEST AND GREAT LAKES REGION SATURDAY INTO SUNDAY. TONIGHT INTO FRIDAY...UPPER LEVEL SHORTWAVE TROUGH OVER EASTERN NEBRASKA AND WESTERN IOWA MOVES NORTHEAST INTO THE GREAT LAKES REGION TONIGHT. BOTH THE 12Z THURSDAY GFS AND NAM INDICATE STRONG MOISTURE TRANSPORT AND CONVERGENCE OVER SOUTHERN FORECAST AREA TONIGHT. THOUGH...BOTH MODELS AT THIS TIME NOT HANDLING SURFACE FEATURES/FORCING AT LOWER LEVELS OF THE ATMOSPHERE ASSOCIATED WITH SHORTWAVE TROUGH. THE LATEST RUC INDICATES STRONGEST MOISTURE TRANSPORT AND CONVERGENCE SOUTH AND SOUTHEAST OF FORECAST AREA BY 03Z FRIDAY. WILL FOLLOW THE LATEST RUC TONIGHT AND REDUCE PRECIPITATION CHANCES ACROSS FORECAST AREA TONIGHT. NEXT SHORTWAVE TROUGH OVER THE ROCKY MOUNTAINS EJECTS OUT INTO THE CENTRAL PLAINS BY 18Z FRIDAY. THE 12Z THURSDAY GFS FARTHER NORTH WITH SURFACE FEATURES/MOISTURE TRANSPORT AND CONVERGENCE THAN NAM. CONFIDENCE IS LOW IN FORECAST FOR FRIDAY...DUE TO THE INCONSISTENCY IN PLACEMENT OF SURFACE FRONT AND ASSOCIATED FORCING. WILL TAKE A MODEL BLEND AND DECREASE PRECIPITATION CHANCES ACROSS FORECAST AREA FRIDAY. SURFACE RIDGE BUILDS INTO FORECAST AREA BY 00Z SUNDAY. BOTH THE MODELS IN GOOD AGREEMENT IN FILTERING COOLER AIR ALOFT INTO THE FORECAST AREA SATURDAY INTO SUNDAY. GOOD SUBSIDENCE UNDERNEATH SURFACE RIDGE WILL ALLOW FOR SKIES TO CLEAR OUT...DRIER WEATHER AND NEAR SEASONABLE TEMPERATURES ACROSS FORECAST AREA. LONG TERM...SUNDAY NIGHT THROUGH THURSDAY MAIN FORECAST CONCERNS ARE PRECIPITATION CHANCES MONDAY INTO WEDNESDAY. BOTH THE 00Z THURSDAY GFS AND ECMWF ARE IN GOOD AGREEMENT WITH FAST WEST TO EAST ZONAL FLOW ACROSS THE NORTHERN TIER STATES THROUGH THE PERIOD. MAIN DIFFERENCES IS TIMING OF SHORTWAVE TROUGH INTO THE UPPER MIDWEST AND NORTHERN PLAINS MONDAY INTO TUESDAY. 00Z THURSDAY GFS SLIGHTLY FASTER THAN ECMWF. THE 00Z THURSDAY GFS ENSEMBLE MEAN AND ARE IN BETTER AGREEMENT WITH TIMING OF SHORTWAVE TROUGH...WILL LEAN CLOSER TO A GFS ENSEMBLE MEAN AND ECMWF SOLUTION. SHORTWAVE RIDGE BUILDS INTO THE UPPER MIDWEST AND GREAT LAKES REGION MONDAY. BOTH THE 00Z THURSDAY GFS AND ECMWF INDICATE STRONG MOISTURE TRANSPORT AND CONVERGENCE OVER WESTERN FORECAST AREA. WITH UPPER LEVEL SHORTWAVE RIDGE...SURFACE WARM FRONT NORTH OF FORECAST AREA AND FORECAST AREA CAPPED...WILL CONTINUE WITH PREVIOUS DRY FORECAST FOR MONDAY INTO MONDAY NIGHT. BOTH THE 00Z THURSDAY GFS AND ECMWF MEAN INDICATE STRONG WARM AIR ADVECTING INTO FORECAST AREA MONDAY WITH 850MB TEMPERATURES RISING TO AROUND 20 DEGREES CELSIUS. SHORTWAVE TROUGH MOVES INTO THE UPPER MIDWEST AND GREAT LAKES REGION TUESDAY INTO WEDNESDAY. THE 00Z THURSDAY ECMWF INDICATING DECENT MOISTURE TRANSPORT AND CONVERGENCE WITH SHORTWAVE TROUGH AND 00Z THURSDAY GFS ENSEMBLES INDICATING 30 TO 50 PERCENT PROBABILITY OF MEASURABLE PRECIPITATION OVER FORECAST AREA TUESDAY INTO WEDNESDAY MORNING. WILL CONTINUE WITH PRECIPITATION CHANCES TUESDAY INTO WEDNESDAY. BOTH THE MODELS BUILD SURFACE RIDGE OVER CANADA INTO THE UPPER MIDWEST AND GREAT LAKES REGION THURSDAY. COOLER AIR WILL ADVECT INTO FORECAST AREA THURSDAY. DRIER WEATHER CONDITIONS AND SLIGHTLY BELOW NORMAL TEMPERATURES CAN BE EXPECTED ACROSS FORECAST AREA. .AVIATION... .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. $$ SHORT-LONG TERM...DTJ AVIATION..........BOYNE && $$ wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 1255 AM EDT SAT AUG 25 2007 .AVIATION...DISCUSSION FOR 06Z TAFS. OCCASIONAL MVFR IN PRECIP WILL BE THE RULE OVERNIGHT WITH BRIEF PERIODS OF IFR POSSIBLE WITH THUNDERSTORMS. ALL OF THIS ACTIVITY WILL OCCUR AHEAD OF A COLD FRONT. SFC WINDS WILL BE LIGHT AND VARIABLE. ALL GUIDANCE POINTS TOWARD MVFR CIGS/VIS DEVELOPING TOWARD 12Z AS THE FRONT NEARS THE AREA. GREATEST CHC FOR MVFR CIGS/VIS WILL PERSIST THROUGH MIDDAY ALONG WITH CHCS FOR ADDITIONAL PRECIP. SFC WINDS WILL BECOME NORTH AFTER 21Z AT ALL SITES HOWEVER REMNANT SFC MOISTURE MAY GIVE RISE TO MORE MVFR VIS AT HUF/BMG AFTER 00Z SUN. && .SHORT TERM /TONIGHT AND SATURDAY DAYTIME/... KIND 88D IS QUIET FOR THE MOMENT. A FEW TSRA WERE POPPING UP OVER SOUTHERN ILLINOIS WITHIN THE WATCH BOX THERE. TSRA TIMING AND FROPA ON SATURDAY WILL BE THE MAIN FOCUS. LAPS DATA SHOWS LIS IN THE -4 TO -6 RANGE WHILE SBCAPES HAVE INCREASED TO 1500-3200 J/KG. A 17Z ACARS OB SHOWS THE LOW LEVEL INVERSION HAS ERODED BUT H7 TEMPS STILL REMAIN WARM AROUND 11C. SPC MESOANALYSIS PAGE SHOWS GENERALLY DECREASING CIN BUT STILL SOME LINGERING AT 18Z. A FEW STORMS IN ILLINOIS CLOSE TO THE INDIANA BORDER HAVE DISSIPATED LIKELY DUE TO THE AFOREMENTIONED CONDITIONS. THEREFORE CONVECTION WILL LIKELY BE DELAYED UNTIL LATER ON THIS EVENING. WOULD NOT EXPECT ANYTHING IN THE CWA BEFORE 21Z. AFTER THAT A LINE OF STORMS WILL PASS THROUGH WITH DAMAGING WIND AND VERY HEAVY RAIN THE MAIN THREAT. A COLD FRONT WAS OVER IOWA THIS AFTERNOON AND WILL SLOWLY PROGRESS SOUTHEAST OVERNIGHT. WILL MOSTLY LEAN TOWARD THE NAM/RUC FOR FROPA THIS FRONT WILL BE THE FOCUS FOR ADDITIONAL PRECIPITATION OVERNIGHT AND INTO SATURDAY. THE FRONT SHOULD BE CLEAR OF THE CWA BY LATE SATURDAY EVENING AND END MOST OF THE RAINFALL. OVERNIGHT LOWS TONIGHT WILL BE IN THE LOW 70S WITH RAIN EXPECTED. ON SATURDAY WITH MOSTLY CLOUDY SKIES ANTICIPATED TEMPS WILL STAY UNDER 90 FOR THE VAST MAJORITY OF THE CWA. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... WL KEEP SLGT CHC OF TRW`S IN SATURDAY EVE AS THE UPR TROF MOVES ACRS AND THE CD FNT SETTLES S OF THE OH RVR. AFTER THAT...SHOULD BE A PERIOD OF TRANQUIL WX AS SFC HIGH PRES SETTLES ACRS THE ERN CONUS WITH RIDGING ALOFT MOVING ACRS THE OH VLY AND A DRY COLUMN WITH MN LVL RH FM 30-40% THROUGH TUE. CHC OF TRW`S AGAIN BY WED IN NW FLOW REGIME. WL NOT BE NEARLY AS WARM FOLLOWING THE FROPA AS SEEN IN CURRENT POST FRONTAL SFC OBS. MOS NUMBERS REFLECT THIS WELL AND ARE PRETTY CLOSE. && .IND WATCHES/WARNINGS/ADVISORIES...SEVERE THUNDERSTORM WATCH 648 UNTIL 11 PM EDT. && $$ AVIATION...CO SHORT TERM...SALLY LONG TERM...MK in AREA FORECAST DISCUSSION...CORRECTED TO REMOVE MENTION OF HEAT ADVISORY... NATIONAL WEATHER SERVICE LOUISVILLE KY 240 AM EDT SAT AUG 25 2007 SHORT TERM (TODAY AND TONIGHT)... MAIN CHALLENGES REVOLVE AROUND SCATTERED CONVECTION ACROSS THE SOUTHERN BLUEGRASS FOR THE FEW HOURS AND POTENTIAL DEVELOPMENT OF THUNDER ALONG/NORTH OF THE OHIO RIVER LATER THIS AFTERNOON. THE RUC 40 CAPTURED THE CURRENT WIDESPREAD EARLY MORNING PRECIP ACROSS CENTRAL TENNESSEE AND SOUTHERN KENTUCKY. IT ACCURATELY FORECAST LOW LEVEL CONVERGENCE AND POOLED MOISTURE. THIS CONVECTION DEVELOPED DURING THE EVENING AIDED BY OUTFLOW BOUNDARIES FROM EARLIER CONVECTION ACROSS THE NORTHERN GULF STATES. ALTHOUGH PRECIP IS QUITE WIDESPREAD CURRENTLY ACROSS A FEW OF OUR SOUTHEASTERN COUNTIES. THE RUC HAS THIS PRECIP GRADUALLY DIMINISHING TOWARD DAWN. FOR NOW...FEEL THAT CONVECTION COVERAGE WILL ERODE NEAR OR SHORTLY AFTER SUNRISE. ANALYSIS OF ATMOSPHERIC PRECIPITABLE WATER CONTENT SHOWS TWO MAXIMA...ONE ACROSS CENTRAL TENNESSEE AND THE OTHER IN INDIANA. A RELATIVE MINIMUM STRETCHES ALONG AND SOUTH OF THE OHIO RIVER. THE CHANCES OF MORNING PRECIP MOVING NORTHEAST OF A BOWLING GREEN TO LEXINGTON LINE IS VERY SMALL. CURRENTLY WEAK LOW PRESSURE IS NEAR DETROIT WITH A DIFFUSE COLD FRONT LYING FROM SOUTHERN MICHIGAN THROUGH SOUTHERN ILLINOIS. THIS WILL MOVE SOUTH AS HIGH PRESSURE BUILDS INTO THE WESTERN GREAT LAKES BY EARLY SUNDAY. WINDS WILL EVENTUALLY SWITCH TO THE NORTH AND SLIGHT COOLER AND DRIER AIR WILL ARRIVE SUNDAY AFTERNOON. SEVERAL MODELS DEVELOP PRECIP ALONG AND BEHIND THE COLD FRONT ACROSS INDIANA BY EARLIER AFTERNOON...BUT LESSENS THE COVERAGE AS IT MOVES SOUTHEASTWARD TOWARDS THE OHIO RIVER BY EARLY EVENING. ALTHOUGH THE MODELS MOISTEN THE ATMOSPHERE A BIT TOWARDS 00Z...THE LACK OF ANY UPPER FORCING OR SURFACE CONVERGENCE MAY LIMIT THE OVERALL COVERAGE OF ANY THUNDERSTORMS. WILL GO WITH CHANCE POPS BEGINNING EARLY AFTERNOON ACROSS OUR NORTHERN COUNTIES...MOVING SOUTH INTO CENTRAL PART OF THE STATE BY LATE EVENING. SOME MID LEVEL CLOUDINESS MAY LIMIT OUR MAXIMUM TEMPERATURES ACROSS OUR SOUTHERN INDIANA AND OUR SOUTHEASTERN COUNTIES...BUT DO EXPECT MID 90S AGAIN. JSD .LONG TERM (SUNDAY THROUGH FRIDAY)... AFTER THE UPPER TROF LIFTS OFF TO THE NORTHEAST BY SUNDAY EVENING...UPPER RIDGING WILL BUILD RIGHT BACK IN FOR MONDAY THROUGH WEDNESDAY. SUNDAY THROUGH WEDNESDAY SHOULD PRIMARILY BE A DRY PERIOD. WE MAY STILL SEE A LINGERING SHOWER OVER THE FAR EAST ON SUNDAY WITH THE UPPER TROF STILL OVERHEAD AND MODELS SUGGESTING AN INVERTED SURFACE TROF FROM LOUISIANA TO THE BLUE GRASS. MOISTURE IS MINIMAL HOWEVER AND ANY FORCING WILL BE WEAK. THE NEXT CHANCE OF RAIN...ALBEIT NOT A LARGE CHANCE...WILL COME AS A VERY WEAK SURFACE COOL FRONT SLIDES SOUTH ACROSS INDIANA AND KENTUCKY WEDNESDAY NIGHT INTO THURSDAY. THE FRONT WILL NOT BE A ROBUST WEATHER MAKER AND WILL NOT HAVE MUCH MOISTURE ASSOCIATED WITH IT SO WILL KEEP POPS IN THE LOW CHANCE CATEGORY FOR MID/LATE WEEK. NO MORE 100 DEGREE READINGS ARE EXPECTED. THE WARMEST DAY NEXT WEEK APPEARS TO BE TUESDAY WITH HIGHS IN THE LOWER TO MIDDLE 90S. 13 && AVIATION (FOR 06Z TAFS)... VFR CONDITIONS EXPECTED FOR THE REST OF THE OVERNIGHT PERIOD. SCATTERED THUNDERSTORMS THROUGH 10Z ACROSS SOUTH CENTRAL KENTUCKY AND THE SOUTHERN BLUEGRASS NOT EXPECTED TO AFFECT BWG. FROM 06Z THROUGH 07Z...SOME ISOLATED THUNDER WILL APPROACH KLEX. WILL PLACE VCTS THROUGH 07Z FOR KLEX...AS IT WILL BE UNLIKELY THAT AN INDIVIDUAL CELL WILL MOVE OVER THE AIRPORT. SCATTERED STORMS WILL END BY 12Z. SKIES WILL BECOME PARTLY CLOUDY WITH MID LEVEL CLOUDS INCREASING BY TOMORROW ACROSS SDF AND LEX...OTHERWISE VFR. SOUTHWEST WINDS WILL INCREASE TO 10 TO 15 MPH WITH HIGHER GUSTS TOMORROW AFTERNOON...SIMILAR TO THOSE WINDS YESTERDAY AFTERNOON. SCATTERED THUNDERSTORMS MAY DEVELOP BY MID AFTERNOON ACROSS SDF AND LEX AND MAY LEAD TO TEMPORARILY IFR CONDITIONS. JSD && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 240 AM EDT SAT AUG 25 2007 SHORT TERM (TODAY AND TONIGHT)... MAIN CHALLENGES REVOLVE AROUND SCATTERED CONVECTION ACROSS THE SOUTHERN BLUEGRASS FOR THE FEW HOURS AND POTENTIAL DEVELOPMENT OF THUNDER ALONG/NORTH OF THE OHIO RIVER LATER THIS AFTERNOON. THE RUC 40 CAPTURED THE CURRENT WIDESPREAD EARLY MORNING PRECIP ACROSS CENTRAL TENNESSEE AND SOUTHERN KENTUCKY. IT ACCURATELY FORECAST LOW LEVEL CONVERGENCE AND POOLED MOISTURE. THIS CONVECTION DEVELOPED DURING THE EVENING AIDED BY OUTFLOW BOUNDARIES FROM EARLIER CONVECTION ACROSS THE NORTHERN GULF STATES. ALTHOUGH PRECIP IS QUITE WIDESPREAD CURRENTLY ACROSS A FEW OF OUR SOUTHEASTERN COUNTIES. THE RUC HAS THIS PRECIP GRADUALLY DIMINISHING TOWARD DAWN. FOR NOW...FEEL THAT CONVECTION COVERAGE WILL ERODE NEAR OR SHORTLY AFTER SUNRISE. ANALYSIS OF ATMOSPHERIC PRECIPITABLE WATER CONTENT SHOWS TWO MAXIMA...ONE ACROSS CENTRAL TENNESSEE AND THE OTHER IN INDIANA. A RELATIVE MINIMUM STRETCHES ALONG AND SOUTH OF THE OHIO RIVER. THE CHANCES OF MORNING PRECIP MOVING NORTHEAST OF A BOWLING GREEN TO LEXINGTON LINE IS VERY SMALL. CURRENTLY WEAK LOW PRESSURE IS NEAR DETROIT WITH A DIFFUSE COLD FRONT LYING FROM SOUTHERN MICHIGAN THROUGH SOUTHERN ILLINOIS. THIS WILL MOVE SOUTH AS HIGH PRESSURE BUILDS INTO THE WESTERN GREAT LAKES BY EARLY SUNDAY. WINDS WILL EVENTUALLY SWITCH TO THE NORTH AND SLIGHT COOLER AND DRIER AIR WILL ARRIVE SUNDAY AFTERNOON. SEVERAL MODELS DEVELOP PRECIP ALONG AND BEHIND THE COLD FRONT ACROSS INDIANA BY EARLIER AFTERNOON...BUT LESSENS THE COVERAGE AS IT MOVES SOUTHEASTWARD TOWARDS THE OHIO RIVER BY EARLY EVENING. ALTHOUGH THE MODELS MOISTEN THE ATMOSPHERE A BIT TOWARDS 00Z...THE LACK OF ANY UPPER FORCING OR SURFACE CONVERGENCE MAY LIMIT THE OVERALL COVERAGE OF ANY THUNDERSTORMS. WILL GO WITH CHANCE POPS BEGINNING EARLY AFTERNOON ACROSS OUR NORTHERN COUNTIES...MOVING SOUTH INTO CENTRAL PART OF THE STATE BY LATE EVENING. SOME MID LEVEL CLOUDINESS MAY LIMIT OUR MAXIMUM TEMPERATURES ACROSS OUR SOUTHERN INDIANA AND OUR SOUTHEASTERN COUNTIES...BUT DO EXPECT MID 90S AGAIN. WILL CONTINUE OUR HEAT ADVISORY FOR OUR SOUTHERN COUNTIES THIS AFTERNOON. JSD .LONG TERM (SUNDAY THROUGH FRIDAY)... AFTER THE UPPER TROF LIFTS OFF TO THE NORTHEAST BY SUNDAY EVENING...UPPER RIDGING WILL BUILD RIGHT BACK IN FOR MONDAY THROUGH WEDNESDAY. SUNDAY THROUGH WEDNESDAY SHOULD PRIMARILY BE A DRY PERIOD. WE MAY STILL SEE A LINGERING SHOWER OVER THE FAR EAST ON SUNDAY WITH THE UPPER TROF STILL OVERHEAD AND MODELS SUGGESTING AN INVERTED SURFACE TROF FROM LOUISIANA TO THE BLUE GRASS. MOISTURE IS MINIMAL HOWEVER AND ANY FORCING WILL BE WEAK. THE NEXT CHANCE OF RAIN...ALBEIT NOT A LARGE CHANCE...WILL COME AS A VERY WEAK SURFACE COOL FRONT SLIDES SOUTH ACROSS INDIANA AND KENTUCKY WEDNESDAY NIGHT INTO THURSDAY. THE FRONT WILL NOT BE A ROBUST WEATHER MAKER AND WILL NOT HAVE MUCH MOISTURE ASSOCIATED WITH IT SO WILL KEEP POPS IN THE LOW CHANCE CATEGORY FOR MID/LATE WEEK. NO MORE 100 DEGREE READINGS ARE EXPECTED. THE WARMEST DAY NEXT WEEK APPEARS TO BE TUESDAY WITH HIGHS IN THE LOWER TO MIDDLE 90S. 13 && AVIATION (FOR 06Z TAFS)... VFR CONDITIONS EXPECTED FOR THE REST OF THE OVERNIGHT PERIOD. SCATTERED THUNDERSTORMS THROUGH 10Z ACROSS SOUTH CENTRAL KENTUCKY AND THE SOUTHERN BLUEGRASS NOT EXPECTED TO AFFECT BWG. FROM 06Z THROUGH 07Z...SOME ISOLATED THUNDER WILL APPROACH KLEX. WILL PLACE VCTS THROUGH 07Z FOR KLEX...AS IT WILL BE UNLIKELY THAT AN INDIVIDUAL CELL WILL MOVE OVER THE AIRPORT. SCATTERED STORMS WILL END BY 12Z. SKIES WILL BECOME PARTLY CLOUDY WITH MID LEVEL CLOUDS INCREASING BY TOMORROW ACROSS SDF AND LEX...OTHERWISE VFR. SOUTHWEST WINDS WILL INCREASE TO 10 TO 15 MPH WITH HIGHER GUSTS TOMORROW AFTERNOON...SIMILAR TO THOSE WINDS YESTERDAY AFTERNOON. SCATTERED THUNDERSTORMS MAY DEVELOP BY MID AFTERNOON ACROSS SDF AND LEX AND MAY LEAD TO TEMPORARILY IFR CONDITIONS. JSD && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 436 AM EDT SAT AUG 25 2007 .DISCUSSION... CURRENT RADAR/WV IMAGERY TRENDS INDICATE ISOLTD SHOWERS CURRENTLY OVER CENTRAL WI OVER TIME WILL TRACK CLOSE TO NORTHERN LAKE MICHIGAN SHORELINE...EXTENDED CURRENT WEATHER GRID EASTWARD TO ACCOUNT FOR THIS. ALSO LIGHT SHOWERS OVER CENTRAL MN WILL TRACK TOWARDS U.P. AND BE NEAR IWD BY 12Z OR SO. OPTED TO ADD IN ISOLATED SHOWERS FOR TODAY. 500MB TROUGH PASSES THROUGH CWA THROUGHOUT THE MORNING AND EARLY AFTN. PREVIOUS THINKING WAS THIS PASSAGE WOULD BE TOO EARLY TO TAP INTO A HEATING CONTRIBUTION. ALSO BETTER DYNAMICS ARE OUT OF THE FA BY THIS TIME. DESPITE THIS...ENOUGH MID LEVEL COOLING LOOKS TO OCCUR TO AT LEAST MENTION SLIGHT CHANCE FOR SHOWERS. FOR NOW COVERAGE LOOKS TO BE WEST AND CENTRAL AS SOUNDINGS OUT EAST STILL LOOK TOO DRY. THIS FEATURE LOOKS TO BE OUT OF HERE BY 00Z. ALSO GIVEN APPEARANCE OF QPF IN NAM/GFS/RUC DURING THIS MORNING AND AFTERNOON MAKES IT EVEN HARDER TO KEEP FCST DRY. HIGH PRESSURE BEGINS TO SETTLE IN BY SAT EVENING...THIS ALONG WITH LIGHT WINDS SHOULD YIELD GOOD RADIATIONAL COOLING. TEMPS IN THE LOW 40S ARE LIKELY. RETURN FLOW ON SUNDAY WILL BRING WARMER TEMPS ALONG WITH INCREASING MOISTURE. BRIEF CLEARING SUNDAY NIGHT WOULD ALLOW FOR GOOD RADIATIONAL COOLING...HOWEVER SURFACE WINDS LOOK TO REMAIN STRONG ENOUGH TO OFFSET RADIATIONAL INFLUENCES. ALSO INCREASING MOISTURE AHEAD OF TUESDAYS FRONTAL PASSAGE WILL LIMIT COOLING AT LEAST IN THE WEST. WILL RAISE LOWS A BIT TO ACCOUNT FOR THIS TREND IN GUIDANCE. SOME INDICATIONS THAT CWA MONDAY MORNING/AFTN COULD SEE PRECIP IN THE WEST. LATEST GUIDANCE...UKMET/GFS/NAM/LOCAL WRF RUNS/GFS ENSEMBLE MEMBERS INDICATE SOME PRECIP. OCCURING IN THE EARLY AFTERNOON...WITH THE MAIN AXIS REMAINING OVER MN. DISCUSSED WITH SURROUNDING OFFICES PUTTING IN PRECIP. BUT OPTED TO WAIT. MON MORN/AFTN LOOKS TO BE CAPPED WITH A STRONG WARM LAYER NOTED AROUND 800-700MB LAYER PER BUFKIT GFS/NAM SOUNDING. STREGHTENING 850MB JET OF 35KT PASSES THROUGH WESTERN HALF OF UPPER MICHIGAN MONDAY AFTN PER 00Z GFS RUN AND THEN STREGHTENS A BIT MORE BY EARLY EVENING. TIMING OF LOW LEVEL JET ISN`T IDEAL AS ITS PASSING LATER IN THE EVENING MIGHT BE MORE IDEAL. SO IF ANY PRECIP. OCCURS ON MONDAY IT WOULD BE ELEVATED...BUFKIT SOUNDING FOR IWD HAS BASES AROUND 750MB. NOT ENOUGH CONFIDENCE NOW TO ADD IN PRECIP BUT WITH MODEL CONSENSUS AS IT IS THIS IS SOMETHING TO MONITOR FOR SURE. TIMING OF FRONT ON TUESDAY IS STILL IFFY. DPROG/DT FOR THE ECMWF SHOWS THE A FASTER TREND FROM THE LAST RUN...ALSO THE FRONT IS MORE OF AN OPEN WAVE AS OPPOSED TO THE INVERTED TROUGH IN THE 00Z RUN FROM YESTERDAY. THE GFS IF ANYTHING THE PAST FOUR RUNS HAS BEEN CONSISTENT WITH ITS TIMING...BRINING THE FRONT TO MID LAKE SUPERIOR BY 6Z TUES AND THRU THE CWA SOMETIME AFTER 12Z. GOOD RUN TO RUN CONSISTENCY WITH THE GFS IS HARD TO IGNORE. THINK THE FINAL SOLUTION CONTINUES TO BE SOMEWHERE IN THE MIDDLE. IN THE END THOUGH THINK A FASTER SOLUTION MAY BE REALIZED. SURROUNDING OFFICES NOTED A SIMILAR THINKING. SEE 12PLANET LOG. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT AN INCRS IN CLD COVER LATE TNGT/EARLY SAT IN ADVANCE OF SHRTWV OVER SD MOVING NEWD TOWARD THE UPR LKS IN SW FLOW ALF. THERE MAY BE SOME LGT -SHRA AHEAD OF THIS SHRTWV ON SAT...BUT DRYNESS OF LLVLS UPSTREAM IN MN AS EVIDENCED BY RECENT TAMDAR SDNGS/RAOBS SUG CIGS WL REMAIN VFR AND ANY PCPN WL BE ON THE LGT SIDE. LOOK FOR IMPROVING CONDITIONS LATER ON SAT FOLLOWING PASSAGE OF THE SHRTWV/ INFLUX OF LK MODIFIED AIR IN THE WAKE OF THIS FEATURE. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT FAIRLY LIGHT WINDS UNDER 20KT OVER LAKE SUPERIOR THROUGH SUN MORNING. THE STRONGER WINDS TODAY (AT TIMES IN THE 15-20KT RANGE) WILL OCCUR OVER EASTERN LAKE SUPERIOR...ESPECIALLY TOWARD THE SE PART OF THE LAKE AS WINDS BECOME NW DURING THE AFTN. WINDS WILL STRENGTHEN SUN AFTN THROUGH MON NIGHT AS PRES GRADIENT TIGHTENS BETWEEN HIGH PRES OVER NEW ENGLAND AND A COLD FRONT APPROACHING FROM THE NORTHERN PLAINS. SHOULD SEE SOUTHERLY 15-25KT WINDS DEVELOP OVER THE E HALF OF LAKE SUPERIOR EARLY SUN EVENING AND PERSIST THRU MON NIGHT. ALTHOUGH SUSTAINED WINDS WILL PROBABLY BE AROUND 20KT FOR THE MOST PART...THERE SHOULD BE FREQUENT GUSTS TO AROUND 30KT... ESPECIALLY AT THE HIGHER OBSERVING PLATFORMS. WINDS WILL BE LIGHTER OVER THE W HALF OF THE LAKE AS THEY COMMONLY ARE IN SOUTHERLY FLOW. COLD FRONT WILL CROSS THE LAKE A LITTLE SOONER ON TUE THAN INDICATED IN PREVIOUS FORECASTS. AT THIS TIME...IT DOES NOT LOOK LIKE WINDS WILL EXCEED 20KT AFTER THE FRONT PASSES. && .MQT WATCHES/WARNINGS/ADVISORIES... NONE && $$ DISCUSSION...PEARSON AVIATION/MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 430 AM CDT SAT AUG 25 2007 .SHORT TERM... PROGRESSIVE UPPER AIR PATTERN WAS OVER THE NORTHERN PLAINS. WATER VAPOR LOOP SHOWS SHORT WAVE TROUGH OVER SOUTHERN MN MOVING EAST. GFS NAM AND CANADIAN ARE SIMILAR WITH THE GFS THE FASTEST. COMPARING THE RADAR VAD WINDS TO THE MODELS THE GFS AND RUC HANDLED LOW LEVEL WINDS BELOW 850 HPA THE BEST COMPARED TO THE NAM. SO THE GFS WILL BE USED. POCKET OF MOISTURE AND CLOUDS AROUND 800 HPA OVER NORTHERN MN WILL TAKE MOST OF THE DAY TO SHIFT EAST. MODEL SOUNDINGS INDICATE A STRONG CAP EXPECTED AROUND 800 HPA ON SUN EVEN THOUGH CAPES INCREASE SIGNIFICANTLY. FRONTAL BOUNDARY MOVES INTO THE REGION MON. WILL NEED LIFT AROUND 800 TO 700 HPA TO OVERCOME INHIBITION MON AFTERNOON IN THE EASTERN ZONES. .LONG TERM... TEMPS TWEAKED. SHORT WAVE FORECAST TO MOVE THROUGH TUE. WILL ADD A CHANCE FOR SHOWERS TUE. && .AVIATION... MID LEVEL CLOUDS REMAIN ACROSS THE NORTHEAST ZONES THIS MORNING. THE CLOUDS MAY TAKE MOST OF THE MORNING AND PERHAPS INTO THE AFTERNOON BEFORE SHIFT TO THE EAST. OTHERWISE VFR CONDITIONS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ HOPPES nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE UPTON NY 1032 AM EDT SAT AUG 25 2007 .SYNOPSIS... WARM AND HUMID CONDITIONS EXPECTED TODAY AS A COLD FRONT REMAINS OFF TO THE WEST...AND SOUTHERLY WINDS CONTINUE TO BRING IN MOIST AIR. THERE WILL BE THE THREAT OF SHOWERS AND THUNDERSTORMS AS THE FRONTAL BOUNDARY APPROACHES. ONCE THE FRONT MOVES THROUGH SATURDAY NIGHT...THE FRONT WILL STALL...KEEPING SHOWERS AND STORMS IN THE FORECAST FOR SUNDAY. BY THE START OF THE NEW WORK WEEK...HIGH PRESSURE WILL BUILD TO THE NORTH...WITH DRIER WEATHER EXPECTED. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LOW CLOUDS AND FOG HANG TOUGH NEAR THE COAST AND FURTHER EAST. SOME EVIDENCE OF THESE CLOUDS BURNING OFF LATE THIS MORNING...AND DO EXPECT THIS TREND TO CONTINUE UNTIL MOST AREAS PARTLY TO MOSTLY SUNNY DURING THE AFTERNOON HOURS. PLENTY OF LOW LEVEL MOISTURE IN PLACE...AND DEW POINTS WILL BE HIGH ENOUGH TO KEEP THE HEAT ADVISORY. THE TOUGH CALL IS TEMPERATURES AS LOW CLOUDS REMAIN. ONCE THEY DO BURN OFF THOUGH...BELIEVE LAV NUMBERS AND TEMPS SHOULD RISE RATHER QUICKLY AND GET INTO THE MID 80S TO LOWER 90S. COULD BE SOME MID 90S IN PORTIONS OF NE NJ. OTHERWISE...LAPS SOUNDINGS AND FORECAST RUC SOUNDINGS THIS MORNING INDICATE PLENTY OF WARM AIR ALOFT...AND AREA REMAINS CAPPED. THERE IS THE POTENTIAL FOR MODERATE INSTABILITY THIS AFTERNOON ONCE TEMPS CLIMB...BUT HARD TO IGNORE MODEL QPF OUTPUT...WITH LITTLE ACROSS CWA THIS AFTERNOON. ENOUGH INHIBITION ALONG WITH LACK OF TRIGGER TO PREVENT WIDESPREAD COVERAGE. COULD BE ISOLATED CELLS...AND ANY TSTM THAT DOES DEVELOP THIS AFTERNOON HAS THE POTENTIAL TO BECOME SEVERE GIVEN 1000 J/KG CAPES...BUT FEEL COVERAGE WILL BE MINIMAL. WILL KEEP SLIGHT CHC POPS NORTH AND WEST. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... APPROACHING COLD FRONT WILL MOVE THROUGH SATURDAY EVENING AND OVERNIGHT NIGHT...BRINGING ADDITIONAL SHOWERS AND THUNDERSTORMS EARLY. THE FRONT WILL HAVE A HARD TIME GETTING TOO FAR OFFSHORE SUNDAY. MOST SHOWERS AND STORMS WILL COME TO AN END OVERNIGHT...HOWEVER WITH INCREASING INSTABILITY AGAIN ON SUNDAY...WE COULD SEE SOME ADDITIONAL SHOWERS AND STORMS. STUCK CLOSE TO THE MOS TEMPS FOR SUNDAY. HIGH PRESSURE BUILDS TO THE NORTH SUNDAY NIGHT AND MONDAY. THE MODELS ARE TRYING TO PICKING UP ON SIMILAR SCENARIO AS WE HAD SEEN EARLIER THIS WEEK WITH REGARD TO MONDAY. ONSHORE EASTERLY FLOW COULD VERY WELL LEAD TO THE FORMATION OF STRATUS AS SPOTTY LIGHT RAIN. THIS WILL IN TURN KEEP TEMPS MUCH LOWER THAN MAVS ARE ADVERTISING. I DID WARM TEMPERATURES A FEW DEGREES FROM WHAT WAS PREVIOUSLY ADVERTISED TO JUST BELOW 80. WE COULD HOWEVER SEE COOLER AIR IN HERE FOR THE START OF THE NEW WEEK UNDER CLOUD COVER. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... COLD FRONT SLOWLY MOVES EAST OF THE AREA RESULTING IN ONSHORE FLOW AS HIGH PRESSURE BUILDS TO OUR NORTH. IT WILL BE INTERESTING TO SEE IF A SIMILAR SITUATION SETS UP AS EARLIER THIS WEEK WITH PERSISTENT EASTERLY FLOW...AND FRONT REMAINING JUST TO OUR SOUTH. BECAUSE OF THIS POSSIBILITY...AND WE CAN SEE THIS WITH MORE CONFIDENCE AS THIS TIME FRAME APPROACHES...WILL UNDERCUT TEMPS SLIGHTLY...JUST UNDER 80. LITTLE CHANCE FOR ANY PRECIPITATION...OTHER THAN SPOTTY LIGHT RAIN IF SIMILAR SCENARIO PANS OUT. KEEPING IT DRY AT THIS TIME...BUT WILL HAVE TO KEEP AN EYE ON THAT POSSIBILITY. THEN THE HIGH WILL MOVE FURTHER OFFSHORE WEDNESDAY...AND UPPER TROUGH WILL STEEP NEXT COLD FRONT TOWARD THE REGION. SOME SHOWERS AND TSTMS POSSIBLE LATE WEDNESDAY AND THURSDAY AS THE FRONT NEARS. LOOKS LIKE MUCH COOLER AND DRIER AIR MOVES IN AS STRONG HIGH PRESSURE MOVES ACROSS THE GREAT LAKES AND BUILDS TO THE NORTH. NORTHEASTERLY WINDS PICK UP IN SPEED FRIDAY BEHIND THE FRONT...AND TEMPERATURES WILL COOL DOWN. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... IFR AND LIFR SHOULD GRADUALLY IMPROVE THIS MORNING. CLIMO FOR SIMILAR SCENARIOS AT AREA AIRPORTS DOES SHOW GRADUAL IMPROVEMENT THROUGH THE MORNING...TO MVFR/VFR BY AROUND 16Z TO 17Z. INCREASED MOISTURE BENEATH LOW LEVEL INVERSION SHOULD STILL RESULT IN SOME AFTERNOON HAZE...MAINLY LOW END VFR VSBY AS S-SW FLOW WILL BE INCREASING TO 10-15 KT...BUT WITH MVFR VSBY IN SPOTS MAINLY AT KHPN/KBDR/KGON NEAR LONG ISLAND SOUND. COASTAL JET DEVELOPMENT MAY HAVE SOUTHERLY WINDS INCREASING TO NEAR 20 KT AT KJFK AFTER 18Z. AN ISOLATED TSTM IS POSSIBLE W TO NYC TERMINALS THIS AFTERNOON WITH LEE-SIDE TROUGH DEVELOPMENT AND MODERATE INSTABILITY. STRONG WINDS WOULD BE MAIN THREAT. CONVECTION WILL BE A THREAT THIS EVENING INTO THE OVERNIGHT...AS COLD FRONT APPROACHES FROM THE GREAT LAKES. STRATUS AND FOG MAY ONCE AGAIN DEVELOP TONIGHT WITH SIMILAR SETUP CONCERNING LIGHTENING SURFACE FLOW COUPLED WITH VERY HIGH MOISTURE CONTENT AIRMASS. IFR CIGS...AND VSBYS ONCE AGAIN POSSIBLE. LLWS WILL ALSO BE PRESENT FOR A COUPLE OF HOURS LATE SAT EVENING INTO THE FIRST PART OF THE OVERNIGHT WITH SW TURNING W LOW LEVEL JET OF 35KT JUST ABOVE THE HEIGHT OF THE INVERSION...1500-2000 FT. THE WIND PROFILE THEN WEAKENS TOWARD DAYBREAK AS COLD FRONT SLIDES INTO THE REGION. OUTLOOK FOR 12Z SUN THROUGH WED...VERY UNCERTAIN OUTLOOK AT THIS POINT. FRONTAL BOUNDARY DOES APPEAR TO SLIDE JUST SOUTH OF THE AREA BY LATE SUN. UNTIL IT DOES THERE COULD BE A THREAT OF A SHRA OR TSRA. THEREAFTER...WE COULD BE LOOKING AT A SIMILAR SETUP TO LAST WEEK WITH A FAIRLY PERSISTENT LOW LEVEL FLOW FROM THE NORTHEAST OR EAST...THAT EVENTUALLY SHIFTS SOUTHEAST TO SOUTH BY MID-WEEK. DEPENDING ON EXACT POSITION OF THE HIGH...AND RH LEVELS OF ITS AIRMASS...WE COULD EITHER BE LOOKING AT VFR THROUGHOUT (NOT LIKELY)...NOCTURNAL LOW STRATUS AND FOG (LIKELY)...OR A PERSISTENT LOW OVERCAST LIKE THIS PAST WED-THU (POSSIBLE). && .MARINE... SOUTHERLY FLOW WILL PERSIST ACROSS THE WATERS UNTIL SUNDAY WHEN AN AREA OF LOW PRESSURE DEVELOPING OVER THE EASTERN GREAT LAKES SLIDES INTO THE CANADIAN MARITIMES DRAGGING ITS ASSOCIATED COLD FRONT ACROSS THE AREA. THE FRONT WILL STALL OUT JUST SOUTH OF THE WATERS SUN NIGHT AS HIGH PRESSURE BUILDS INTO NEW ENGLAND. THE HIGH WILL SLIDE OFF THE NEW ENGLAND COAST ON TUESDAY ALLOWING ANOTHER COLD FRONT TO SLOWLY APPROACH FROM THE WEST. WILL CONTINUE THE SCA FOR SEAS FROM FIRE ISLAND TO MONTAUK POINT AS THE SOUTHERLY FLOW STRENGTHENS ON THIS AFTERNOON INTO TONIGHT... INCREASING SEAS TO MARGINAL SCA LEVELS. OTHERWISE...NO FLAGS ARE ANTICIPATED DURING THE PERIOD. && .HYDROLOGY... SCATTERED SHOWERS AND THUNDERSTORMS EXPECTED THROUGH THE WEEKEND. AS ALWAYS...LOCALIZED URBAN FLOODING IS POSSIBLE IN ANY HEAVIER CONVECTION.. AT THIS TIME...NO WIDESPREAD JUMPS IN AREA RIVERS AND STREAMS ARE EXPECTED. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...HEAT ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR NYZ072>076. NJ...HEAT ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR NJZ003>006-011. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 PM THIS AFTERNOON TO 6 AM EDT SUNDAY FOR ANZ350-353. && $$ NEAR TERM/AVIATION UPDATE...PW ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 1110 AM EDT SAT AUG 25 2007 .MORNING UPDATE... AT 15Z A COOL FRONTAL BOUNDARY EXTENDEDD FROM ST LOUIS NORTHEAST INTO CENTRAL MICHIGAN. SCATTERED THUNDERSTORMS WERE OCCURING ALONG AND SOUTH OF THE FRONT BUT WERE MAINLY CONFINED TO CENTRAL AND NORTHERN INDIANA. A WEAK BOUNDARY WAS NOTED ON SATELLITE WHICH STRETCHED FROM CINCINNATI SOUTHWEST TO BOWLING GREEN. WE EXPECT THIS BOUNDARY TO CONTINUE TO DROP SLOWLY SOUTHEAST THIS AFTERNOON AND THIS MAY BECOME THE FOCUS FOR SOME STORM DEVELOPMENT ACROSS CENTRAL KENTUCKY. WITH THIS IN MIND WE WILL MENTION LOW CHANCE POPS ACROSS ALL THE FORECAST AREA. IT STILL MAY BE A FEW HOURS BEFORE STORMS DEVELOP AS THE LATEST BUFKIT FORECAST SOUNDINGS INDICATE A CAP FOR A FEW MORE HOURS. WE WILL ALSO ADJUST TEMPERATURES UP SEVERAL DEGREES ACROSS THE NORTH WITH THE LACK OF THICK CLOUD COVER. FORECAST OUT BY 11:15AM. --JA .MORNING UPDATE... UPDATED FORECAST TO REMOVE EARLY MORNING POPS FROM SOUTHEASTERN COUNTIES. ALSO HIGHLIGHTED SOME LIGHT SHOWER ACTIVITY ACROSS SOUTHERN INDIANA. DEPENDING ON EXTENT AND TIMING OF THESE SHOWERS...TEMPERATURES MAY BE KEPT DOWN ACROSS OUR NORTHERN COUNTIES...AND HAVE REFLECTED THIS WITHIN THE GRIDS...HOLDING TEMPS IN DUBOIS AND ADJACENT COUNTIES DOWN IN THE MID 80S. JSD SHORT TERM (TODAY AND TONIGHT)... MAIN CHALLENGES REVOLVE AROUND SCATTERED CONVECTION ACROSS THE SOUTHERN BLUEGRASS FOR THE FEW HOURS AND POTENTIAL DEVELOPMENT OF THUNDER ALONG/NORTH OF THE OHIO RIVER LATER THIS AFTERNOON. THE RUC 40 CAPTURED THE CURRENT WIDESPREAD EARLY MORNING PRECIP ACROSS CENTRAL TENNESSEE AND SOUTHERN KENTUCKY. IT ACCURATELY FORECAST LOW LEVEL CONVERGENCE AND POOLED MOISTURE. THIS CONVECTION DEVELOPED DURING THE EVENING AIDED BY OUTFLOW BOUNDARIES FROM EARLIER CONVECTION ACROSS THE NORTHERN GULF STATES. ALTHOUGH PRECIP IS QUITE WIDESPREAD CURRENTLY ACROSS A FEW OF OUR SOUTHEASTERN COUNTIES. THE RUC HAS THIS PRECIP GRADUALLY DIMINISHING TOWARD DAWN. FOR NOW...FEEL THAT CONVECTION COVERAGE WILL ERODE NEAR OR SHORTLY AFTER SUNRISE. ANALYSIS OF ATMOSPHERIC PRECIPITABLE WATER CONTENT SHOWS TWO MAXIMA...ONE ACROSS CENTRAL TENNESSEE AND THE OTHER IN INDIANA. A RELATIVE MINIMUM STRETCHES ALONG AND SOUTH OF THE OHIO RIVER. THE CHANCES OF MORNING PRECIP MOVING NORTHEAST OF A BOWLING GREEN TO LEXINGTON LINE IS VERY SMALL. CURRENTLY WEAK LOW PRESSURE IS NEAR DETROIT WITH A DIFFUSE COLD FRONT LYING FROM SOUTHERN MICHIGAN THROUGH SOUTHERN ILLINOIS. THIS WILL MOVE SOUTH AS HIGH PRESSURE BUILDS INTO THE WESTERN GREAT LAKES BY EARLY SUNDAY. WINDS WILL EVENTUALLY SWITCH TO THE NORTH AND SLIGHT COOLER AND DRIER AIR WILL ARRIVE SUNDAY AFTERNOON. SEVERAL MODELS DEVELOP PRECIP ALONG AND BEHIND THE COLD FRONT ACROSS INDIANA BY EARLIER AFTERNOON...BUT LESSENS THE COVERAGE AS IT MOVES SOUTHEASTWARD TOWARDS THE OHIO RIVER BY EARLY EVENING. ALTHOUGH THE MODELS MOISTEN THE ATMOSPHERE A BIT TOWARDS 00Z...THE LACK OF ANY UPPER FORCING OR SURFACE CONVERGENCE MAY LIMIT THE OVERALL COVERAGE OF ANY THUNDERSTORMS. WILL GO WITH CHANCE POPS BEGINNING EARLY AFTERNOON ACROSS OUR NORTHERN COUNTIES...MOVING SOUTH INTO CENTRAL PART OF THE STATE BY LATE EVENING. SOME MID LEVEL CLOUDINESS MAY LIMIT OUR MAXIMUM TEMPERATURES ACROSS OUR SOUTHERN INDIANA AND OUR SOUTHEASTERN COUNTIES...BUT DO EXPECT MID 90S AGAIN. JSD .LONG TERM (SUNDAY THROUGH FRIDAY)... AFTER THE UPPER TROF LIFTS OFF TO THE NORTHEAST BY SUNDAY EVENING...UPPER RIDGING WILL BUILD RIGHT BACK IN FOR MONDAY THROUGH WEDNESDAY. SUNDAY THROUGH WEDNESDAY SHOULD PRIMARILY BE A DRY PERIOD. WE MAY STILL SEE A LINGERING SHOWER OVER THE FAR EAST ON SUNDAY WITH THE UPPER TROF STILL OVERHEAD AND MODELS SUGGESTING AN INVERTED SURFACE TROF FROM LOUISIANA TO THE BLUE GRASS. MOISTURE IS MINIMAL HOWEVER AND ANY FORCING WILL BE WEAK. THE NEXT CHANCE OF RAIN...ALBEIT NOT A LARGE CHANCE...WILL COME AS A VERY WEAK SURFACE COOL FRONT SLIDES SOUTH ACROSS INDIANA AND KENTUCKY WEDNESDAY NIGHT INTO THURSDAY. THE FRONT WILL NOT BE A ROBUST WEATHER MAKER AND WILL NOT HAVE MUCH MOISTURE ASSOCIATED WITH IT SO WILL KEEP POPS IN THE LOW CHANCE CATEGORY FOR MID/LATE WEEK. NO MORE 100 DEGREE READINGS ARE EXPECTED. THE WARMEST DAY NEXT WEEK APPEARS TO BE TUESDAY WITH HIGHS IN THE LOWER TO MIDDLE 90S. 13 AVIATION (FOR 12Z TAFS)... ONLY A FEW MID LEVEL CLOUDS EXPECTED AT LEX AND BWG THROUGH EARLY AFTERNOON. AS A COLD FRONT APPROACHES THIS EVENING SCATTERED THUNDER MAY DEVELOP AFTER 20Z. MID LEVEL CLOUDS WILL INCREASE AT SDF BY EARLY AFTERNOON. SCATTERED SHOWERS WITH POSSIBLE EMBEDDED THUNDER IS EXPECTED BY 17Z. CIGS MAY GO OVERCAST AS SOME POINT THIS AFTERNOON...BUT CIGS (OUTSIDE OF ANY STORMS) SHOULD STAY VFR. WEST WINDS WILL INCREASE THIS AFTERNOON TO AROUND 10 MPH...WITH A FEW HIGHER GUSTS. PRECIPITATION CHANCES WILL END BY TOMORROW MORNING AS WIND SHIFT TO THE NORTH AND DRIER AIR ARRIVES. JSD .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 630 AM EDT SAT AUG 25 2007 AVIATION (FOR 12Z TAFS)... ONLY A FEW MID LEVEL CLOUDS EXPECTED AT LEX AND BWG THROUGH EARLY AFTERNOON. AS A COLD FRONT APPROACHES THIS EVENING SCATTERED THUNDER MAY DEVELOP AFTER 20Z. MID LEVEL CLOUDS WILL INCREASE AT SDF BY EARLY AFTERNOON. SCATTERED SHOWERS WITH POSSIBLE EMBEDDED THUNDER IS EXPECTED BY 17Z. CIGS MAY GO OVERCAST AS SOME POINT THIS AFTERNOON...BUT CIGS (OUTSIDE OF ANY STORMS) SHOULD STAY VFR. WEST WINDS WILL INCREASE THIS AFTERNOON TO AROUND 10 MPH...WITH A FEW HIGHER GUSTS. PRECIPITATION CHANCES WILL END BY TOMORROW MORNING AS WIND SHIFT TO THE NORTH AND DRIER AIR ARRIVES. JSD && .MORNING UPDATE... UPDATED FORECAST TO REMOVE EARLY MORNING POPS FROM SOUTHEASTERN COUNTIES. ALSO HIGHLIGHTED SOME LIGHT SHOWER ACTIVITY ACROSS SOUTHERN INDIANA. DEPENDING ON EXTENT AND TIMING OF THESE SHOWERS...TEMPERATURES MAY BE KEPT DOWN ACROSS OUR NORTHERN COUNTIES...AND HAVE REFLECTED THIS WITHIN THE GRIDS...HOLDING TEMPS IN DUBOIS AND ADJACENT COUNTIES DOWN IN THE MID 80S. JSD SHORT TERM (TODAY AND TONIGHT)... MAIN CHALLENGES REVOLVE AROUND SCATTERED CONVECTION ACROSS THE SOUTHERN BLUEGRASS FOR THE FEW HOURS AND POTENTIAL DEVELOPMENT OF THUNDER ALONG/NORTH OF THE OHIO RIVER LATER THIS AFTERNOON. THE RUC 40 CAPTURED THE CURRENT WIDESPREAD EARLY MORNING PRECIP ACROSS CENTRAL TENNESSEE AND SOUTHERN KENTUCKY. IT ACCURATELY FORECAST LOW LEVEL CONVERGENCE AND POOLED MOISTURE. THIS CONVECTION DEVELOPED DURING THE EVENING AIDED BY OUTFLOW BOUNDARIES FROM EARLIER CONVECTION ACROSS THE NORTHERN GULF STATES. ALTHOUGH PRECIP IS QUITE WIDESPREAD CURRENTLY ACROSS A FEW OF OUR SOUTHEASTERN COUNTIES. THE RUC HAS THIS PRECIP GRADUALLY DIMINISHING TOWARD DAWN. FOR NOW...FEEL THAT CONVECTION COVERAGE WILL ERODE NEAR OR SHORTLY AFTER SUNRISE. ANALYSIS OF ATMOSPHERIC PRECIPITABLE WATER CONTENT SHOWS TWO MAXIMA...ONE ACROSS CENTRAL TENNESSEE AND THE OTHER IN INDIANA. A RELATIVE MINIMUM STRETCHES ALONG AND SOUTH OF THE OHIO RIVER. THE CHANCES OF MORNING PRECIP MOVING NORTHEAST OF A BOWLING GREEN TO LEXINGTON LINE IS VERY SMALL. CURRENTLY WEAK LOW PRESSURE IS NEAR DETROIT WITH A DIFFUSE COLD FRONT LYING FROM SOUTHERN MICHIGAN THROUGH SOUTHERN ILLINOIS. THIS WILL MOVE SOUTH AS HIGH PRESSURE BUILDS INTO THE WESTERN GREAT LAKES BY EARLY SUNDAY. WINDS WILL EVENTUALLY SWITCH TO THE NORTH AND SLIGHT COOLER AND DRIER AIR WILL ARRIVE SUNDAY AFTERNOON. SEVERAL MODELS DEVELOP PRECIP ALONG AND BEHIND THE COLD FRONT ACROSS INDIANA BY EARLIER AFTERNOON...BUT LESSENS THE COVERAGE AS IT MOVES SOUTHEASTWARD TOWARDS THE OHIO RIVER BY EARLY EVENING. ALTHOUGH THE MODELS MOISTEN THE ATMOSPHERE A BIT TOWARDS 00Z...THE LACK OF ANY UPPER FORCING OR SURFACE CONVERGENCE MAY LIMIT THE OVERALL COVERAGE OF ANY THUNDERSTORMS. WILL GO WITH CHANCE POPS BEGINNING EARLY AFTERNOON ACROSS OUR NORTHERN COUNTIES...MOVING SOUTH INTO CENTRAL PART OF THE STATE BY LATE EVENING. SOME MID LEVEL CLOUDINESS MAY LIMIT OUR MAXIMUM TEMPERATURES ACROSS OUR SOUTHERN INDIANA AND OUR SOUTHEASTERN COUNTIES...BUT DO EXPECT MID 90S AGAIN. JSD .LONG TERM (SUNDAY THROUGH FRIDAY)... AFTER THE UPPER TROF LIFTS OFF TO THE NORTHEAST BY SUNDAY EVENING...UPPER RIDGING WILL BUILD RIGHT BACK IN FOR MONDAY THROUGH WEDNESDAY. SUNDAY THROUGH WEDNESDAY SHOULD PRIMARILY BE A DRY PERIOD. WE MAY STILL SEE A LINGERING SHOWER OVER THE FAR EAST ON SUNDAY WITH THE UPPER TROF STILL OVERHEAD AND MODELS SUGGESTING AN INVERTED SURFACE TROF FROM LOUISIANA TO THE BLUE GRASS. MOISTURE IS MINIMAL HOWEVER AND ANY FORCING WILL BE WEAK. THE NEXT CHANCE OF RAIN...ALBEIT NOT A LARGE CHANCE...WILL COME AS A VERY WEAK SURFACE COOL FRONT SLIDES SOUTH ACROSS INDIANA AND KENTUCKY WEDNESDAY NIGHT INTO THURSDAY. THE FRONT WILL NOT BE A ROBUST WEATHER MAKER AND WILL NOT HAVE MUCH MOISTURE ASSOCIATED WITH IT SO WILL KEEP POPS IN THE LOW CHANCE CATEGORY FOR MID/LATE WEEK. NO MORE 100 DEGREE READINGS ARE EXPECTED. THE WARMEST DAY NEXT WEEK APPEARS TO BE TUESDAY WITH HIGHS IN THE LOWER TO MIDDLE 90S. 13 .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 735 AM EDT SAT AUG 25 2007 UPDATED FOR AVIATION DISCUSSION .DISCUSSION (ISSUED AT 436 AM EDT)... CURRENT RADAR/WV IMAGERY TRENDS INDICATE ISOLTD SHOWERS CURRENTLY OVER CENTRAL WI OVER TIME WILL TRACK CLOSE TO NORTHERN LAKE MICHIGAN SHORELINE...EXTENDED CURRENT WEATHER GRID EASTWARD TO ACCOUNT FOR THIS. ALSO LIGHT SHOWERS OVER CENTRAL MN WILL TRACK TOWARDS U.P. AND BE NEAR IWD BY 12Z OR SO. OPTED TO ADD IN ISOLATED SHOWERS FOR TODAY. 500MB TROUGH PASSES THROUGH CWA THROUGHOUT THE MORNING AND EARLY AFTN. PREVIOUS THINKING WAS THIS PASSAGE WOULD BE TOO EARLY TO TAP INTO A HEATING CONTRIBUTION. ALSO BETTER DYNAMICS ARE OUT OF THE FA BY THIS TIME. DESPITE THIS...ENOUGH MID LEVEL COOLING LOOKS TO OCCUR TO AT LEAST MENTION SLIGHT CHANCE FOR SHOWERS. FOR NOW COVERAGE LOOKS TO BE WEST AND CENTRAL AS SOUNDINGS OUT EAST STILL LOOK TOO DRY. THIS FEATURE LOOKS TO BE OUT OF HERE BY 00Z. ALSO GIVEN APPEARANCE OF QPF IN NAM/GFS/RUC DURING THIS MORNING AND AFTERNOON MAKES IT EVEN HARDER TO KEEP FCST DRY. HIGH PRESSURE BEGINS TO SETTLE IN BY SAT EVENING...THIS ALONG WITH LIGHT WINDS SHOULD YIELD GOOD RADIATIONAL COOLING. TEMPS IN THE LOW 40S ARE LIKELY. RETURN FLOW ON SUNDAY WILL BRING WARMER TEMPS ALONG WITH INCREASING MOISTURE. BRIEF CLEARING SUNDAY NIGHT WOULD ALLOW FOR GOOD RADIATIONAL COOLING...HOWEVER SURFACE WINDS LOOK TO REMAIN STRONG ENOUGH TO OFFSET RADIATIONAL INFLUENCES. ALSO INCREASING MOISTURE AHEAD OF TUESDAYS FRONTAL PASSAGE WILL LIMIT COOLING AT LEAST IN THE WEST. WILL RAISE LOWS A BIT TO ACCOUNT FOR THIS TREND IN GUIDANCE. SOME INDICATIONS THAT CWA MONDAY MORNING/AFTN COULD SEE PRECIP IN THE WEST. LATEST GUIDANCE...UKMET/GFS/NAM/LOCAL WRF RUNS/GFS ENSEMBLE MEMBERS INDICATE SOME PRECIP. OCCURING IN THE EARLY AFTERNOON...WITH THE MAIN AXIS REMAINING OVER MN. DISCUSSED WITH SURROUNDING OFFICES PUTTING IN PRECIP. BUT OPTED TO WAIT. MON MORN/AFTN LOOKS TO BE CAPPED WITH A STRONG WARM LAYER NOTED AROUND 800-700MB LAYER PER BUFKIT GFS/NAM SOUNDING. STREGHTENING 850MB JET OF 35KT PASSES THROUGH WESTERN HALF OF UPPER MICHIGAN MONDAY AFTN PER 00Z GFS RUN AND THEN STREGHTENS A BIT MORE BY EARLY EVENING. TIMING OF LOW LEVEL JET ISN`T IDEAL AS ITS PASSING LATER IN THE EVENING MIGHT BE MORE IDEAL. SO IF ANY PRECIP. OCCURS ON MONDAY IT WOULD BE ELEVATED...BUFKIT SOUNDING FOR IWD HAS BASES AROUND 750MB. NOT ENOUGH CONFIDENCE NOW TO ADD IN PRECIP BUT WITH MODEL CONSENSUS AS IT IS THIS IS SOMETHING TO MONITOR FOR SURE. TIMING OF FRONT ON TUESDAY IS STILL IFFY. DPROG/DT FOR THE ECMWF SHOWS THE A FASTER TREND FROM THE LAST RUN...ALSO THE FRONT IS MORE OF AN OPEN WAVE AS OPPOSED TO THE INVERTED TROUGH IN THE 00Z RUN FROM YESTERDAY. THE GFS IF ANYTHING THE PAST FOUR RUNS HAS BEEN CONSISTENT WITH ITS TIMING...BRINING THE FRONT TO MID LAKE SUPERIOR BY 6Z TUES AND THRU THE CWA SOMETIME AFTER 12Z. GOOD RUN TO RUN CONSISTENCY WITH THE GFS IS HARD TO IGNORE. THINK THE FINAL SOLUTION CONTINUES TO BE SOMEWHERE IN THE MIDDLE. IN THE END THOUGH THINK A FASTER SOLUTION MAY BE REALIZED. SURROUNDING OFFICES NOTED A SIMILAR THINKING. SEE 12PLANET LOG. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... FAIRLY IMPRESSIVE LOOKING UPPER LEVEL DISTURBANCE LIFTING ENE THRU THE UPPER GREAT LAKES LOOKS LIKE IT WILL PASS UNEVENTFULLY THIS MORNING. SYSTEM WAS PRODUCING SOME SCT -SHRA UPSTREAM EARLIER THIS MORNING...BUT THOSE -SHRA HAVE DISSIPATED. A COUPLE OF -SHRA OR SPRINKLES STILL CAN`T BE RULED OUT...BUT AT THIS POINT...IT`S NOT WORTH A MENTION AT EITHER KCMX/KSAW. VFR CONDITIONS WILL PREVAIL FOR THIS ENTIRE FCST PERIOD. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT FAIRLY LIGHT WINDS UNDER 20KT OVER LAKE SUPERIOR THROUGH SUN MORNING. THE STRONGER WINDS TODAY (AT TIMES IN THE 15-20KT RANGE) WILL OCCUR OVER EASTERN LAKE SUPERIOR...ESPECIALLY TOWARD THE SE PART OF THE LAKE AS WINDS BECOME NW DURING THE AFTN. WINDS WILL STRENGTHEN SUN AFTN THROUGH MON NIGHT AS PRES GRADIENT TIGHTENS BETWEEN HIGH PRES OVER NEW ENGLAND AND A COLD FRONT APPROACHING FROM THE NORTHERN PLAINS. SHOULD SEE SOUTHERLY 15-25KT WINDS DEVELOP OVER THE E HALF OF LAKE SUPERIOR EARLY SUN EVENING AND PERSIST THRU MON NIGHT. ALTHOUGH SUSTAINED WINDS WILL PROBABLY BE AROUND 20KT FOR THE MOST PART...THERE SHOULD BE FREQUENT GUSTS TO AROUND 30KT... ESPECIALLY AT THE HIGHER OBSERVING PLATFORMS. WINDS WILL BE LIGHTER OVER THE W HALF OF THE LAKE AS THEY COMMONLY ARE IN SOUTHERLY FLOW. COLD FRONT WILL CROSS THE LAKE A LITTLE SOONER ON TUE THAN INDICATED IN PREVIOUS FORECASTS. AT THIS TIME...IT DOES NOT LOOK LIKE WINDS WILL EXCEED 20KT AFTER THE FRONT PASSES. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ DISCUSSION...PEARSON AVIATION/MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 1000 AM CDT SAT AUG 25 2007 .UPDATE... INHERITED FORECAST IN GOOD SHAPE THIS MORNING WITH ONLY ONE MINOR CHANGE ANTICIPATED. PREVIOUS FORECAST HAD THE NORTHEAST FA MOSTLY CLOUDY TODAY WHERE CLOUDS ARE MOVING OFF PRETTY QUICKLY. WILL THEREFORE LOWER CLOUD AMOUNTS A BIT IN THIS AREA TODAY (LOOKS LIKE THE ENTIRE AREA SHOULD SEE A LOT OF SUN). STARTING A LITTLE COOLER THAN YESTERDAY...ESPECIALLY ALONG THE CANADIAN BORDER IN NORTH DAKOTA. WILL REALLY NOT SEE MUCH RETURN FLOW UNTIL LATE... SO WINDS WILL STAY RATHER LIGHT FOR MOST OF THE DAY (VERY WEAK WARM ADVECTION). THEREFORE WILL DEPEND MOSTLY ON THE POWER OF THE SUN FOR HEATING TODAY. WILL LOOK FOR HIGHS A FEW DEGREES WARMER THAN FRIDAY...WHICH IS WHAT THE FORECAST HAD GOING. && .PREV DISCUSSION... /ISSUED 430 AM CDT SAT AUG 25 2007/ SHORT TERM... PROGRESSIVE UPPER AIR PATTERN WAS OVER THE NORTHERN PLAINS. WATER VAPOR LOOP SHOWS SHORT WAVE TROUGH OVER SOUTHERN MN MOVING EAST. GFS NAM AND CANADIAN ARE SIMILAR WITH THE GFS THE FASTEST. COMPARING THE RADAR VAD WINDS TO THE MODELS THE GFS AND RUC HANDLED LOW LEVEL WINDS BELOW 850 HPA THE BEST COMPARED TO THE NAM. SO THE GFS WILL BE USED. POCKET OF MOISTURE AND CLOUDS AROUND 800 HPA OVER NORTHERN MN WILL TAKE MOST OF THE DAY TO SHIFT EAST. MODEL SOUNDINGS INDICATE A STRONG CAP EXPECTED AROUND 800 HPA ON SUN EVEN THOUGH CAPES INCREASE SIGNIFICANTLY. FRONTAL BOUNDARY MOVES INTO THE REGION MON. WILL NEED LIFT AROUND 800 TO 700 HPA TO OVERCOME INHIBITION MON AFTERNOON IN THE EASTERN ZONES. LONG TERM... TEMPS TWEAKED. SHORT WAVE FORECAST TO MOVE THROUGH TUE. WILL ADD A CHANCE FOR SHOWERS TUE. AVIATION... MID LEVEL CLOUDS REMAIN ACROSS THE NORTHEAST ZONES THIS MORNING. THE CLOUDS MAY TAKE MOST OF THE MORNING AND PERHAPS INTO THE AFTERNOON BEFORE SHIFT TO THE EAST. OTHERWISE VFR CONDITIONS. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ GODON nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 1018 AM CDT SAT AUG 25 2007 .UPDATE... MADE SOME MINOR TWEAKS TO FORECAST THIS MORNING MAINLY TO ADJUST CLOUDS/POPS. WELL DEFINED UPPER LEVEL SHORTWAVE ON WATER VAPOR CONTINUES TO SLIDE EWD...WITH 12Z RAOB 500/300MB PLOTS SHOWING NICE HEIGHT FALL/RISE COUPLET OVER THE MIDWEST. RUC/GFS/NAM ALL INDICATE DEEP LAYER Q-VECTOR DIVERGENCE /AND IMPLIED SUBIDENCE/ SPREADING INTO AREA BY AFTERNOON. GOES PRECIP WATER SOUNDER ALSO SHOWING DRIER AIR SPREADING IN FROM THE WEST LATE THIS MORNING AND AFTERNOON. HOWEVER...RUC SOUNDINGS DO INDICATE THE POTENTIAL FOR A NARROW WINDOW OF INSTABILITY TO DEVELOP IN THE EAST FROM 17Z- 21Z WITH CAPE VALUES AROUND 200-300 J/KG. LOCAL 4KM WRF-ARW MESOSCALE MODELS ALSO BEAR THIS OUT...WITH WEAK SIMULATED ECHOES INDICATED IN THE SAME TIMEFRAME. THUS WILL HOLD ONTO ISOLATED RAIN CHANCES BASICALLY EAST OF A LINE FROM FOND DU LAC TO WATERTOWN TO JANESVILLE. OTHEWISE...EXPECT MAINLY JUST FLAT CU WEST AS SUBSIDENCE INVERSION CAPS ACTIVITY. && .MKX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FOWLE wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 322 PM MDT SAT AUG 25 2007 .SHORT TERM... (TNGT AND SUN) MAIN FORECAST CHALLENGE WILL BE THE DEVELOPMENT OF THUNDERSTORMS THIS AFTN THROUGH EVE...AND STRATUS/FOG ACROSS ERN CO AGAIN LATE TNGT-EARLY SUN MORNING. CURRENTLY...WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES SHOWED A RELATIVELY FLAT NWLY FLOW OVER THE CNTRL ROCKIES...AND HARD TO DISCERN A SHORTWAVE TROUGHS RIPPLING THROUGH THE FLOW. RUC40 DOES HINT AT A H3-H2 PV POSITIVE LOBE MOVING THROUGH SRN CO...WHICH COULD HELP TRIGGER MOIST CONVECTION. VISIBLE SATELLITE IMAGERY INDICATED MUCH OF THE LIFR-MVFR STRATUS/FOG ACROSS WRN CO HAS DISSIPATED BY LATE MORNING...EXCEPT FOR ALONG THE CO/KS BORDER. PLENTY OF CONVECTIVE JUICE IN THE ATMOSPHERE GIVEN LOWER 60S DEW POINTS ACROSS ERN CO. LAPS DATA HAS SURFACE-BASED CAPE VALUES OF 500-3K J/KG...BUT WITH CAPPING INVERSION STILL IN PLACE. LIFTED INDICES RUNNING AROUND -2C TO -4C. VERTICAL SHEAR NOT TOO BAD WITH 0-6KM BULK SHEAR VALUES OF 20-40KTS IN RESPONSE TO THE LOW LEVEL S-SE FLOW JUXTAPOSED WITH MIDDLE/UPPER LEVEL NWLY FLOW. VISIBLE/IR SATELLITE IMAGERY ANIMATION SHOWED CU/TCU DEVELOPING MAINLY OVER THE SWRN CO MOUNTAINS...SO FAR. FIRST CELL WENT UP JUST EAST OF KRTN ALONG CO/NM BORDER. LATE THIS AFTN AND TNGT...BIG CHALLENGES WITH TSTMS DEVELOPING OVER THE NEXT 6-8 HOURS. ALL THERMAL INGREDIENTS ARE IN-PLACE...BUT JUST WAITING FOR THE TRIGGER. RUC40 IS ALREADY A LITTLE OVERDONE WITH BREAKING OUT PRECIPITATION ACROSS ERN CO AND THIS MAY BE A RESULT OF A FAIRLY MOIST SFC-PBL LAYER. NAM12 WANTS TO BREAK OUT PRECIPITATION OVER THE SWRN CO MOUNTAINS AND SRN SANGRE DE CRISTO MOUNTAINS/SOUTHERN FOOTHILLS LATER THIS AFTN AND CONTINUE INTO THE ADJACENT VALLEYS/PLAINS THROUGH THE EVE. THERE IS A HINT OF A CELL OR TWO DEVELOPING OVER PIKES PEAK/PALMER DIVIDE...TOO. PLAN TO MAINTAIN CURRENT LOW POPS/WX THROUGH THIS EVE. THE NEXT CHALLENGE WILL BE THE DEVELOPMENT OF STRATUS/FOG ACROSS ERN CO AGAIN TNGT. GIVEN SOME WEAK WARM AIR ADVECTION ALOFT...LEE SIDE SURFACE TROUGH DEVELOPS OVER ERN CO AND A LOW LEVEL JET STREAK STRENGTHENS ACROSS EXTREME ERN CO AND WRN KS. THERE MIGHT BE TOO MUCH WIND FOR RADIATIONAL STRATUS/FOG TO DEVELOP. THE DEEPER SFC-H8 MOISTURE SHOULD BE ACROSS WRN KS WHERE ADVECTION STRATUS/FOG MAY DEVELOP. THERE MAY BE TOO MUCH TURBULENT MIXING NEAR THE SURFACE OR IN THE LOW LEVEL JET STREAK FOR STRATUS/FOG TO DEVELOP ACROSS SERN CO PLAINS...BUT I GUESS THERE IS STILL A VERY LOW POTENTIAL OUT AROUND KLHX/KLAA AND NEARBY. SUN...MORE WEAK H3-H2 PV POSITIVE LOBES MIGRATE THROUGH THE CNTRL ROCKIES DURING PEAK CONVECTIVE INSTABILITY. SURFACE DEW POINTS ARE PROGGED TO DRY OUT A LITTLE. PLAN TO MAINTAIN CURRENT LOW POPS/WX WITH THE MAIN THREAT BEING SMALL HAIL...GUSTY WINDS...AND CLOUD TO GROUND LIGHTNING DURING THE AFTN. METZE .LONG TERM... (SUNDAY NIGHT THROUGH SATURDAY) SUNDAY NIGHT-MONDAY NIGHT...MID AND UPPER LEVEL MOISTURE PROGGED TO INCREASE IN THE WEST TO SOUTHWEST FLOW ACROSS THE REGION AS PAC NW UPPER TROUGH AND ASSOCIATED COLD FRONT CONTINUES ACROSS THE INTERMOUNTAIN WEST AND ACROSS THE NORTHERN ROCKIES MONDAY NIGHT. MODELS KEEPING BEST UPPER SUPPORT NORTH OF THE REGION THOUGH DO INDICATE SOME UVV TO WORK WITH THE INCREASING MOISTURE TO KEEP ISOLATED TO SCATTERED POPS ACROSS THE AREA SUNDAY NIGHT AND MONDAY WITH THE BEST POPS ACROSS THE CONTINENTAL DVD. LEE TROUGHING ACROSS THE EASTERN PLAINS SUNDAY NIGHT PROGGED TO MOVE AROUND THE KANSAS BORDER MONDAY WHICH ALLOWS FOR A WEAK NORTHERLY SURGE TO MOVE TO NEAR THE PALMER DVD MONDAY AFTERNOON AND STALLS ALONG OR JUST SOUTH OF THE ARKANSAS RIVER MONDAY EVENING. LATEST NAM ALLOWS FOR SOME INCREASING LOW LEVEL MOISTURE IN THE LOW LEVEL FLOW ACROSS THE PLAINS TO WORK WITH WEAK UVV FOR ISOLATED TO SCATTERED POPS MONDAY AFTERNOON AND EVENING. TUESDAY-WEDNESDAY...UPPER TROUGH CONTINUES ACROSS THE NORTHERN ROCKIES AND ACROSS THE NORTHERN HIGH PLAINS...WITH ASSOCIATED FRONT SLIDING ACROSS THE EASTERN PLAINS TUESDAY. LATEST NAM A TAD FASTER WITH FRONT WHICH HAS FRONT INTO NORTHEASTERN NEW MEXICO EARLY WEDNESDAY MORNING WHEREAS GFS A TAD SLOWER. AT ANY RATE...HAVE GONE WITH THE FASTER SOLUTION...KEEPING BEST CHANCES OF PRECIP ACROSS THE EASTERN MTS AND PLAINS TUESDAY AFTERNOON AND EVENING WITH MOIST LOW LEVEL UPSLOPE FLOW DEVELOPING. WITH THE MOIST UPSLOPE FLOW...COULD SEE STRATUS DEVELOPING ACROSS THE PLAINS TUESDAY NIGHT AND EARLY WEDNESDAY MORNING...WHICH COULD KEEP THE PLAINS TOO STABLE FOR ANY PRECIP WEDNESDAY AFTERNOON. WITH THAT IN MIND...I TRIMMED POPS A TAD ACROSS THE PLAINS WEDNESDAY...KEEPING BEST POPS ACROSS THE MOUNTAINS AND IMMEDIATE ADJACENT PLAINS. THURSDAY-SATURDAY...LATEST MODELS INDICATING NORTH TO NORTHWEST FLOW ALOFT DEVELOPING ACROSS THE REGION AS UPPER LEVEL RIDGING ACROSS THE DESERT SW BUILDS INTO THE FOUR CORNERS REGION. MODELS ALSO INDICATING HARD TO TIME SHORT WAVES EMBEDDED IN THE FLOW ALOFT MOVING ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS....KEEP GENERALLY COOL UPSLOPE FLOW IN PLACE ACROSS THE REGION. WITH THAT SAID...HAVE KEPT TEMPS AROUND SEASONAL AVERAGES ACROSS THE PLAINS WITH AT OR ABOVE SEASONAL TEMPS FOR WESTERN PORTIONS OF THE AREA...ALONG WITH GENERALLY ISOLATED POPS THROUGH THE PERIOD. -MW && .AVIATION... ISOLD-SCT SHRA/TSRA MAY AFFECT THE KALS...KCOS...AND KPUB TERMINAL AREAS...BUT THE PROBABILITY IS TOO LOW TO ADD TO THE TAFS. ANY CONVECTIVE DEBRIS CLOUD SHOULD DISSIPATE AROUND OR SHORTLY AFTER MIDNIGHT LEAVING A RELATIVELY CLEAR SKY THROUGH 18Z/26. THERE IS THE POTENTIAL FOR IFR-MVFR STRATUS/FOG TO DEVELOP IN THE FAR SERN CO PLAINS BETWEEN 06Z/26-17Z/26. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 17/23 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 250 PM CDT SAT AUG 25 2007 .DISCUSSION MAJOR RAINS HAVE DEPARTED AND ARE ENTERING INTO NEW AIR MASS. UPR TROF STILL NOT QUITE THRU WITH SOME CYCLONIC CURVATURE OVER MOST OF AREA. RUC INDICATING VORT MAX STRETCHING FROM UGN TO ERN IA AND WORKING SE THRU NRN IL THIS AFTN. POST-VORT SUBSIDENCE IS EVIDENT ON VIS SATL ENTERING NW IL. BUT AHEAD OF THIS FEATURE...AFTN HEATING OCNLY POPPING BRIEF SMALL SHOWERS. HAVE TAKEN RAIN OUT FOR NOW BUT WILL PROBLY RE-INSERT AN ISOLATED MENTION FOR EARLY EVENING IN SOUTH AND SOUTHEAST. ENHANCED BREEZE FROM LAKE IS STEADILY RACING WEST THRU OHARE TO JOT AND DPA BY 400 PM. WILL NOT BE BOTHERING WITH RAIN CHANCES BEHIND THIS FEATURE. RUC SHOWING SLIGHT TROFING IN UPR FLOW MOVING INTO NW IL AFTER DARK THIS EVENING AND PROBLY DIVING SE IN WRN SECTIONS OF FCST AREA. THIS SLIGHTLY REFLECTED IN OTHER MODELS BUT SHUD HAVE NEGLIGIBLE IMPACT OVERNIGHT WITH LOSS OF DAYTIME HEATING AND DRYING IN MID LVLS. RADIATIVE DECOUPLING IN LOWER LVL WILL WEAKEN WINDS TO NEAR CALM AND WITH SO MUCH SFC MSTR BEING TRAPPED...WILL LIKELY BE FOGGING UP. UPS FOG PRGM OUTPUTS AN INDEX OF 0.5 AND A -4 CROSSOVER...SUGGESTING AREAS LESS THAN 1/2 MI OVERNIGHT. WILL NOT ISSUE DENSE FOG ADVISORY NOW BUT WILL SEE HOW MUCH AND HOW SOON FOG STARTS DROPPING THIS EVENING TO ASCERTAIN A BETTER FEEL ON FOG INTENSITY OVERNIGHT. WITH HIGH PRESSURE BLDG OVER AREA SUNDAY AND UNDER COMPLETE ANTICYCLONIC FLOW...WILL EXPECT CLEAR SKIES SUNDAY INTO MONDAY. RIDGING MOVING EAST ACRS THE LAKES WILL PERMIT SOUTH FLOW TO RETURN AND ADVECT CI/AC UP MS VLY INTO NRN IL. MAY HAVE MORE AREAS OF FOG SUN NGT WITH LIGHT WINDS AND MOSTLY CLEAR SKIES...BUT WILL NOT PUT IN FCST FOR NOW. APPEARS NEXT CHC OF RAIN WILL CONTINUE TO BE TUES NGT AND WED. MODELS ATTEMPTING TO SWING WEAK UPR TROF THRU MON NGT BUT SOUNDINGS LOOK TOO DRY TO INSERT RAIN CHANCES AT THAT POINT. AFTER WEDNESDAY...WILL CONTINUE THE WEEK DRY WITH NEAR NORMAL HIGHS AND SLIGHTLY SUBNORMAL LOWS. RLB && .AVIATION... 115 PM CDT SURFACE COLD FRONT CONTINUES TO TRACK SOUTHEAST ACROSS SOUTHERN ILLINOIS INTO CENTRAL INDIANA THIS AFTERNOON. DIURNAL CU HAS DEVELOPED BEHIND THIS FRONT AND IS ENHANCED WEST OF THE LAKE MICHIGAN SHORELINE WHERE LOW LEVEL CONVERGENCE IS A BIT STRONGER. FORECAST/ACARS SOUNDINGS DO INDICATE 100-200 J/KG OF SFC BASED CAPE ALONG FOR SOME VERTICAL EXTENT WITH THE CU FIELD. MAIN UPPER LEVEL TROUGH AXIS ALSO IS CURRENTLY TRACKING THROUGH NORTHERN ILLINOIS LIKELY AIDING IN CU COVERAGE THIS AFTERNOON. MAY SEE A FEW ISOLD SHOWERS DEVELOP GIVEN THE ABOVE FACTORS BUT WITH LIMITED COVERAGE WILL NOT INCLUDE IN TERMINALS. BY LATE THIS AFTERNOON/EVENING THIS SHORT WAVE WILL TRACK EAST OF THE AREA BRINGING IN SYNOPTIC SCALE SUBSIDENCE. SUBSIDENCE AND LOSS OF HEATING TOWARD EVENING SHOULD RESULT IN CLEARING SKIES EARLY THIS EVENING. NORTH WINDS AROUND 10 KNOTS BEHIND THIS FRONT SHOULD VEER NORTHEAST LATE THIS AFTERNOON/EARLY THIS EVENING AND LESSEN IN SPEEDS WITH DECOUPLING THIS EVENING...AND THEN BECOMING LIGHT AND VARIABLE THIS EVENING. MAIN CONCERN LATER TONIGHT WILL BE POTENTIAL FOR FOG FORMATION. WITH RELATIVELY SHALLOW BOUNDARY LAYER DEPTHS THIS AFTERNOON...DEW POINTS ARE STILL UP IN THE LOWER TO MID 60S. COMBINATION OF CLEARING SKIES...LIGHT WINDS...WET SOILS...AND LINGERING LOW LEVEL MOISTURE SHOULD LEAD TO SOME SHALLOW FOG FORMATION TONIGHT. WILL CONTINUE TO CARRY IFR VSBYS AT RFD/DPA LATE TONIGHT AND MVFR VSBYS ACROSS REMAINDER OF THE TERMINALS. VSBYS SHOULD IMPROVE TO VFR BY 14Z SUNDAY WITH CU DEVELOPMENT EXPECTED AGAIN BY MID MORNING TOMORROW. BASED ON LOW LEVEL MOISTURE PROFILES...BASES SHOULD ONCE AGAIN BE FAIRLY LOW INITIALLY LOW...IN THE 2500-3500 FT RANGE. HOWEVER BY AFTERNOON...EXPECTING CU TO BECOME HIGHER BASED WITH A DEEPER MIXED LAYER TOMORROW. MARSILI && .MARINE... 235 PM CDT WINDS AND WAVES WILL CONTINUE TO SUBSIDE THIS EVENING AS HIGH PRESSURE BUILDS INTO THE WESTERN GREAT LAKES REGION THROUGH SUNDAY. WINDS WILL BECOME EAST/SOUTHEAST TOMORROW AFTERNOON AS THE SURFACE HIGH MOVES OFF THE EAST. NEXT PACIFIC DISTURBANCE WILL RACE ACROSS SOUTHERN CANADA THROUGH TUESDAY ALLOWING FOR ANOTHER TROUGH OF LOW PRESSURE TO DEVELOP ACROSS THE NORTHERN PLAINS. SFC PRESSURE GRADIENT WILL TIGHTEN IN RESPONSE TO THIS SHORT WAVE MONDAY WITH SOME GUSTS TO AROUND 25 KNOTS POSSIBLE ACROSS THE NORTHERN HALF OF LAKE MICHIGAN. WIND SHIFT WITH THIS TROUGH IS EXPECTED LATE TUESDAY AFTERNOON. IN TERMS OF THE NEARSHORE...SMALL CRAFT ADVISORIES ARE CURRENTLY IN EFFECT THROUGH EARLY EVENING. HOWEVER...IT APPEARS AS THOUGH WINDS AND WAVES ARE SUBSIDING SOMEWHAT FROM EARLIER THIS MORNING IMMEDIATELY BEHIND THE FRONT. && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SCA IN EFFECT THROUGH EARLY EVENING. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 125 PM EDT SAT AUG 25 2007 AVIATION (FOR 18Z TAFS)... A WEAK COOL FRONT WILL DROP ACROSS CENTRAL KENTUCKY DURING THIS FORECAST PERIOD. A FEW SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON ALONG AND AHEAD OF THE FRONT BUT WIDESPREAD RAIN IS NOT EXPECTED. VFR CONDITIONS ARE EXPECTED BUT SOME MVFR CIGS AND VSBYS WILL BE POSSIBLE IN THUNDERSTORMS. --JA .MORNING UPDATE... AT 15Z A COOL FRONTAL BOUNDARY EXTENDED FROM ST LOUIS NORTHEAST INTO CENTRAL MICHIGAN. SCATTERED THUNDERSTORMS WERE OCCURING ALONG AND SOUTH OF THE FRONT BUT WERE MAINLY CONFINED TO CENTRAL AND NORTHERN INDIANA. A WEAK BOUNDARY WAS NOTED ON SATELLITE WHICH STRETCHED FROM CINCINNATI SOUTHWEST TO BOWLING GREEN. WE EXPECT THIS BOUNDARY TO CONTINUE TO DROP SLOWLY SOUTHEAST THIS AFTERNOON AND THIS MAY BECOME THE FOCUS FOR SOME STORM DEVELOPMENT ACROSS CENTRAL KENTUCKY. WITH THIS IN MIND WE WILL MENTION LOW CHANCE POPS ACROSS ALL THE FORECAST AREA. IT STILL MAY BE A FEW HOURS BEFORE STORMS DEVELOP AS THE LATEST BUFKIT FORECAST SOUNDINGS INDICATE A CAP FOR A FEW MORE HOURS. WE WILL ALSO ADJUST TEMPERATURES UP SEVERAL DEGREES ACROSS THE NORTH WITH THE LACK OF THICK CLOUD COVER. FORECAST OUT BY 11:15AM. --JA .MORNING UPDATE... UPDATED FORECAST TO REMOVE EARLY MORNING POPS FROM SOUTHEASTERN COUNTIES. ALSO HIGHLIGHTED SOME LIGHT SHOWER ACTIVITY ACROSS SOUTHERN INDIANA. DEPENDING ON EXTENT AND TIMING OF THESE SHOWERS...TEMPERATURES MAY BE KEPT DOWN ACROSS OUR NORTHERN COUNTIES...AND HAVE REFLECTED THIS WITHIN THE GRIDS...HOLDING TEMPS IN DUBOIS AND ADJACENT COUNTIES DOWN IN THE MID 80S. JSD SHORT TERM (TODAY AND TONIGHT)... MAIN CHALLENGES REVOLVE AROUND SCATTERED CONVECTION ACROSS THE SOUTHERN BLUEGRASS FOR THE FEW HOURS AND POTENTIAL DEVELOPMENT OF THUNDER ALONG/NORTH OF THE OHIO RIVER LATER THIS AFTERNOON. THE RUC 40 CAPTURED THE CURRENT WIDESPREAD EARLY MORNING PRECIP ACROSS CENTRAL TENNESSEE AND SOUTHERN KENTUCKY. IT ACCURATELY FORECAST LOW LEVEL CONVERGENCE AND POOLED MOISTURE. THIS CONVECTION DEVELOPED DURING THE EVENING AIDED BY OUTFLOW BOUNDARIES FROM EARLIER CONVECTION ACROSS THE NORTHERN GULF STATES. ALTHOUGH PRECIP IS QUITE WIDESPREAD CURRENTLY ACROSS A FEW OF OUR SOUTHEASTERN COUNTIES. THE RUC HAS THIS PRECIP GRADUALLY DIMINISHING TOWARD DAWN. FOR NOW...FEEL THAT CONVECTION COVERAGE WILL ERODE NEAR OR SHORTLY AFTER SUNRISE. ANALYSIS OF ATMOSPHERIC PRECIPITABLE WATER CONTENT SHOWS TWO MAXIMA...ONE ACROSS CENTRAL TENNESSEE AND THE OTHER IN INDIANA. A RELATIVE MINIMUM STRETCHES ALONG AND SOUTH OF THE OHIO RIVER. THE CHANCES OF MORNING PRECIP MOVING NORTHEAST OF A BOWLING GREEN TO LEXINGTON LINE IS VERY SMALL. CURRENTLY WEAK LOW PRESSURE IS NEAR DETROIT WITH A DIFFUSE COLD FRONT LYING FROM SOUTHERN MICHIGAN THROUGH SOUTHERN ILLINOIS. THIS WILL MOVE SOUTH AS HIGH PRESSURE BUILDS INTO THE WESTERN GREAT LAKES BY EARLY SUNDAY. WINDS WILL EVENTUALLY SWITCH TO THE NORTH AND SLIGHT COOLER AND DRIER AIR WILL ARRIVE SUNDAY AFTERNOON. SEVERAL MODELS DEVELOP PRECIP ALONG AND BEHIND THE COLD FRONT ACROSS INDIANA BY EARLIER AFTERNOON...BUT LESSENS THE COVERAGE AS IT MOVES SOUTHEASTWARD TOWARDS THE OHIO RIVER BY EARLY EVENING. ALTHOUGH THE MODELS MOISTEN THE ATMOSPHERE A BIT TOWARDS 00Z...THE LACK OF ANY UPPER FORCING OR SURFACE CONVERGENCE MAY LIMIT THE OVERALL COVERAGE OF ANY THUNDERSTORMS. WILL GO WITH CHANCE POPS BEGINNING EARLY AFTERNOON ACROSS OUR NORTHERN COUNTIES...MOVING SOUTH INTO CENTRAL PART OF THE STATE BY LATE EVENING. SOME MID LEVEL CLOUDINESS MAY LIMIT OUR MAXIMUM TEMPERATURES ACROSS OUR SOUTHERN INDIANA AND OUR SOUTHEASTERN COUNTIES...BUT DO EXPECT MID 90S AGAIN. JSD .LONG TERM (SUNDAY THROUGH FRIDAY)... AFTER THE UPPER TROF LIFTS OFF TO THE NORTHEAST BY SUNDAY EVENING...UPPER RIDGING WILL BUILD RIGHT BACK IN FOR MONDAY THROUGH WEDNESDAY. SUNDAY THROUGH WEDNESDAY SHOULD PRIMARILY BE A DRY PERIOD. WE MAY STILL SEE A LINGERING SHOWER OVER THE FAR EAST ON SUNDAY WITH THE UPPER TROF STILL OVERHEAD AND MODELS SUGGESTING AN INVERTED SURFACE TROF FROM LOUISIANA TO THE BLUE GRASS. MOISTURE IS MINIMAL HOWEVER AND ANY FORCING WILL BE WEAK. THE NEXT CHANCE OF RAIN...ALBEIT NOT A LARGE CHANCE...WILL COME AS A VERY WEAK SURFACE COOL FRONT SLIDES SOUTH ACROSS INDIANA AND KENTUCKY WEDNESDAY NIGHT INTO THURSDAY. THE FRONT WILL NOT BE A ROBUST WEATHER MAKER AND WILL NOT HAVE MUCH MOISTURE ASSOCIATED WITH IT SO WILL KEEP POPS IN THE LOW CHANCE CATEGORY FOR MID/LATE WEEK. NO MORE 100 DEGREE READINGS ARE EXPECTED. THE WARMEST DAY NEXT WEEK APPEARS TO BE TUESDAY WITH HIGHS IN THE LOWER TO MIDDLE 90S. 13 .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky