AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 610 PM CST WED NOV 17 2004 .DISCUSSION.... AS OF 20 UTC SUBJECTIVE ANALYSIS OF SFC/UA IN CONJUNCTION WITH SAT AND RUC-20 IMAGERY REVEALED A PLETHORA OF FEATURES RELEVANT TO THIS FCST PACKAGE. THE PERSISTENT BERMUDA HIGH RESPONSIBLE FOR OUR RELATIVELY MILD NOV TEMPS WAS BEGINNING TO BREAK DOWN AND MIGRATE SOUTHEAST TOWARD THE SE U.S COAST WITH A PORTION OF ITS ATTENDANT MID-LVL RIDGE AXIS MOVING INTO AND ACROSS NRN IL. A LOW AMPLITUDE S/WV TROUGH OVER LOWER MI HAD ORPHANED ITS SFC-H85 COLD FRONT AS IT TRANSLATED EAST ATOP THE BERMUDA HIGH'S RIDGE. AN ELONGATED/ASYMMETRIC CUTOFF LOW CENTERED OVER THE TX PHNDL-WTX WAS WELL TAPPED INTO THE GOM MOISTURE AND BEGINNING TO SLOWLY TRANSLATE NEWARD. IN BETWEEN THE CUTOFF LOW AND RIDGE AXIS EXISTED AN INCREASING MIDLVL CONFLUENCE ZONE DENOTING THE AXIS OF GREATEST WAA. A DAMPENING S/WV TROUGH OVER ERN KS WAS ROTATING NORTH ALONG THE CONFLUENCE ZONE. AHEAD OF THE WAVE, SHRA HAD DEVELOPED ACROSS ERN NE AND WRN IA. AT THE SFC A WEAK SFC LOW WAS PARKED OVER SE MN WITH ITS ATTENDANT WARM FRONT EXTENDING FROM THE LOW ACROSS THE LOWER PORTION OF THE CWA AND INTO SRN IN. SCT-BKN SKIES EXISTED ALONG AND SOUTH OF THE FRONT. MEANWHILE A RELATIVELY UNDISTURBED AIRMASS NORTH OF 62N AND WEST OF 75W CONTINUED TO COOL OVER ITS SOURCE REGION. FOR TONIGHT FG SHOULD REDEVELOP EARLY, AS SOME CLEARING DEVELOPS OVER THE WRN/SRN PORTIONS OF THE CWA. THEN LATER TONIGHT, THE SHRA OVER ERN NE/WRN IA SHOULD WORK INTO THE CWA AS THE SUPPORTING WAVE CONTINUES TO PROPAGATE ALONG THE CONFLUENCE ZONE. AS THE WAVE EXITS TO OUR EAST A WEAK BAROCLINIC ZONE (COLD FRONT) WILL WORK INTO THE NRN PORTION OF THE CWA EARLY TOMORROW. DPROG/DT OF THE ETA/GFS INDICATE THE FRONT WILL NOT MAKE IT FAR SOUTH INTO IL BEFORE MIXING NORTH ON FRIDAY AS A WARM FRONT. THIS APPEARS REASONABLE GIVEN THE CONFLUENCE ZONE IS CURRENTLY DRAPPED W/E ACROSS THE IL/WI BORDER WITH A WEAK H85-H7 BAROCLINIC ZONE WELL NORTH ACROSS MN AND WI. STATED ANOTHER WAY...IT WILL BE DIFFICULT FOR SUCH A SHALLOW FRONT TO PROPAGATE SOUTH THROUGH THE CWA TOMORROW GIVEN FLOW THAT IS PARALLEL TO THE BNDRY. HIGH TEMPS SHOULD BE A BIT COOLER TOMORROW ACROSS NRN IL. ADDED POPS FOR THE ENTIRE DAY ON THR GIVEN ANTICIPATED MORNING SHRA RA WANING AND AFTERNOON PRECIP WAXING. THE AFTERNOON PRECIP WILL BE THE LEADING PRECIP ASSOC WITH THE CURRENT WTX LOW, THAT SHOULD BE RAPIDLY MOVING NEWARD THR NIGHT INTO FRI. WIDESPREAD RA APPEARS A GOOD BET THR NIGHT INTO FRI. TEMPS ON FRI CONTINUE TO BE WELL ABOVE NORMAL. THE ACTIVITY SHOULD DECREASE IN AREAL COVERAGE FRI AFTERNOON/NIGHT WITH THE PASSAGE OF WAVES' POSITIVELY TILTED TROUGH AXIS. SPOTTY PRECIP SHOULD LINGER OVER THE REGION ON SAT ALONG WITH ONE LAST DAY OF MILD TEMPS. THE UPSHOT IS COLD AIR IS NOT EXPECTED TO ARRIVE UNTIL SUN BEHIND THE DEPARTING SYSTEM. FURTHERMORE, THE AIRMASS DOESN'T APPEAR OVERLY CHILLED. IN FACT, NEARLY ALL MEDIUM RANGE OPERATIONAL GUIDANCE AND RELATED ENSEMBLE SUITES INDICATE WARMER TEMPS FOR NEXT WEEK COMPARED TO THE FACE-VALUE DEPICTION THAT WAS DISCUSSION YESTERDAY...COOLER TO BE SURE BUT NOTHING DRASTIC COMPARED TO NORMALS. EVEN THE MID WEEK COLD FRONT DOESN'T APPEAR TO TAP INTO THE DEVELOPING CA AIRMASS...ITS ONLY A MATTER OF TIME. AEP && .AVIATION DISCUSSION FOR 00Z TAFS... CEILINGS/VISIBILITIES WILL CONTINUE TO BE MAIN FORECAST CONCERN FOR THIS CYCLE. GENERALLY MVFR CIGS/VSBYS CURRENTLY ACROSS FORECAST AREA WITH PARTIAL CLEARING ACROSS CENTRAL ILLINOIS. WEAK SURFACE TROUGH LOCATED ACROSS SOUTHERN WISCONSIN THROUGH CENTRAL IOWA WILL HAVE TROUBLE TRACKING SOUTH TONIGHT AS MORE SUBSTANTIAL VORT MAX TRACKS THROUGH SOUTHERN CANADA WITH LITTLE TO PUSH THIS BOUNDARY SOUTH THROUGH NORTHERN ILLINOIS OVERNIGHT. STILL PLENTY OF LOW LEVEL MOISTURE SOUTH OF THIS BOUNDARY WITH DEW POINTS RUNNING IN THE MIDDLE AND UPPER 50S AND NIGHTTIME COOLING AND STRENGTHENING INVERSION TONIGHT SHOULD SUPPORT RETURN OF IFR CIGS AFTER 10Z. BOUNDARY MAKES SLOW PUSH THROUGH TERMINALS LATE TOMORROW MORNING WITH NORTH WINDS OF AROUND 10 KNOTS BY 18Z. CONDITIONS SHOULD IMPROVE TO MVFR BY MID MORNING GIVEN DIURNAL EFFECTS AND SOME SLIGHTLY DRIER AIR ADVECTING SOUTHWARD BEHIND THE FRONT. CONCERN FOR AFTER 18Z WILL BE EVOLUTION OF UPPER LEVEL SHORT WAVE ACROSS NORTHERN TEXAS AS IT LIFTS NORTHEAST. MODEL PROGS SUGGESTING SOME COUPLING OF NORTHERN AND SOUTHERN STREAM JET STREAKS TOMORROW EVENING WITH INCREASING PRECIP COVERAGE...BUT BETTER CHANCE OF RAIN SHOWERS LOOKS TO OCCUR PROBABLY TOWARD THE VERY END OF THE FORECAST PERIOD SO DOES NOT SEEM WORTH A MENTION AT THIS POINT. NDM && $$ .LOT...WATCHES/WARNINGS/ADVISORIES... .IL...NONE .IN...NONE .LK MI...NONE $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 1155 AM CST WED NOV 17 .AVIATION DISCUSSION FOR 18Z TAFS... AS BEFORE...CIGS REMAIN PRIMARY AVN WX CONCERN. LOW LEVEL MOISTURE AXIS FROM WRN GULF MEX INTO NRN IL TODAY...WITH INVERSION ALOFT PREVENTING MUCH MIXING. EXTENSIVE AREA IFR/LIFR DVLPD ACROSS FCST AREA LAST NGT...AND WITH ABOVE CONDITIONS HAVING A TOUGH TIME IMPROVING THINGS EVEN THIS AFTN. SOME THINNING/RAISING OF CIGS TO MVFR CAT ACROSS ERN IA...AND WITH MODEST DIURNAL WARMING THIS AFTN HAVE INDICATED SLGT IMPROVMENT...BUT EXPECT LOWERING BACK TO IFR AGAIN THIS EVE GIVEN PERSISTENT MOIST ADVECTION AND INVERSION. WEAK COLD FRONTAL BOUNDARY FROM NRN WI TO ERN NEB THIS AFTN FCST BY ETA/GFS TO SLIP INTO NRN IL/NW IND LATE TNGT...WITH WEAK WINDSHIFT TO NW BY 12Z THU. MODELS HAVE CONSISTENTLY BACKED OFF ON SOUTHWARD PUSH OF THIS BOUNDARY...AND NOW DEPICT FRONT HANGING UP ACROSS FCST AREA AS NEXT STRONGER S/WV MOVES INTO AREA THU NGT. ETA MORE BULLISH WITH LLVL DRYING BEHIND THIS FEATURE BY THU MORNING...HOWEVER ETA NOT DOING A REAL GOOD JOB WITH LOW CIGS ATTM...AND GIVEN POTENTIAL FOR FRONT TO NOT MAKE IT TOO MUCH FARTHER SOUTH THAN I-80 PREFER LINGERING LOW LVL RH SEEN IN GFS TIME HEIGHT SECTIONS. THUS EXPECT RETURN TO IFR CONDITIONS TONIGHT AND INTO EARLY THU WITH ONLY VERY WEAK DRY LLVL ADVCTN. HAVE INDICATED TREND TOWARD LOW MVFR AFT 14Z OR SO...THOUGH THIS MAY BE OPTIMISTIC. COULD BE SOME DRIZZLE AT TIMES WITH MOIST LOW LEVELS...THOUGH UVM APPEARS MINIMAL FOR ANY ORGANIZED RA UNTIL AFT 18Z THU AS WAA INCRS AHEAD OF NXT S/WV TROUGH. AS FOR WINDS...SW 6-8 KTS THROUGH THIS EVE...WITH GRADUAL SHIFT TO NW AFT MIDNIGHT...AGAIN REMAINING BLO 10 KTS. RATZER && .MORNING UPDATE DISCUSSION... THICK STRATUS, SCATTERED -SHRA, AND/OR -DZ AND FG CONTINUE TO PERSIST ACROSS THE CWA THIS MORNING. BASED ON 12 UTC RAOBS, PROFILER/88D/SAT TRENDS COUPLED WITH RUC-20 ISENTROPIC AND Q (MIXING RATIO) ANALYSIS ALL INDICATE THE LIGHT AND SCATTERED PRECIP IS EXPECTED TO HOLD OVER THE REGION INTO THE AFTERNOON WITH THE CLOUD COVER HOLDING UNDER A STRENGTHENING INVERSION. WILL HAVE AN UPDATED ZFP OUT SHORTLY. 05 ...PREVIOUS MORNING AFD BELOW... VORT MAX MOVING ACROSS WIS THIS MORNING WITH BAND OF SHOWERS MOVING ACROSS THE GREAT LAKES. TAIL END OF THE SHOWERS MOVING ACROSS NE IL BUT SHOULD BE ALL BUT OVER BY DAYBREAK. WILL KEEP MENTION OF SHOWERS OVER NW IN AND CHANCE OF DRIZZLE ELSEWHERE INTO MID MORNING. OTHERWISE MOST OF THE DAY SHOULD BE DRY BUT CONTINUED OVERCAST. SOME THICKER FOG FORMING OVER NRN IA AND MN WHERE CLOUD DECK APPEARS TO HAVE CLEARED OR THINNED SUBSTANTIALLY IN SUBSIDENCE BEHIND DEPARTING VORT MAX. HOWEVER...IT LOOKS LIKE NRN IL AND IN SHOULD HAVE DEEP ENOUGH CLOUD COVER TODAY TO PREVENT ANY SIGNIFICANT FOG. VISIBILITIES WILL BE GENERALLY 4 TO 6 MILES SO WILL DROP FOG WORDING FROM FORECAST FOR NOW. NEXT WEAK DISTURBANCE TO MOVE ACROSS THE TOP OF THE RIDGE INTO THE GREAT LAKES TONIGHT. WILL HAVE SOME LIGHT RAIN AND DRIZZLE AGAIN TONIGHT...DRYING OUT THURSDAY MORNING. FINALLY MEX UPPER LOW TO LIFT OUT INTO IL BY FRI. THIS SHOULD BRING A SIGNIFICANT RAIN TO THE AREA AFTER MIDNIGHT THURSDAY NIGHT THROUGH THE DAY FRIDAY. FINALLY DRYING OUT SATURDAY AS WAVE CONTINUES LIFTING NE INTO GREAT LAKES. WILL KEEP FORECAST DRY THROUGH THE MIDDLE OF NEXT WEEK. MOS TEMPERATURES FOR TODAY CONTINUE TO RUN TOO WARM GIVEN THE EXTENT OF CLOUD COVER. WILL TEMPER TO LOWER 60S TODAY. WEAK COLD FRONT SLIPS THROUGH THURSDAY BUT NOT MUCH TEMPERATURE CHANGE EXPECTED. NOTICEABLY COOLER FRIDAY WITH EAST WINDS AND STEADY RAIN. STILL LOOKS LIKE STEADY OR SLOWLY RISING TEMPS LATE FRIDAY NIGHT INTO SATURDAY MORNING AS SURFACE LOW AND WARM FRONT LIFT THROUGH NRN IL. TURNING COOLER SAT AFTERNOON. SEASONABLY COOL AIRMASS SETTLES IN FOR EARLY NEXT WEEK. GFS INDICATES THAT COLD AIR MASS WAY UP IN NRN CANADA FINALLY GETS TAPPED MID WEEK. WILL HAVE TO WAIT AND SEE. ALLSOPP $$ .LOT...WATCHES/WARNINGS/ADVISORIES... .IL...NONE .IN...NONE .LK MI...NONE $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO IL 915 AM CST WED NOV 17 .DISCUSSION... THICK STRATUS, SCATTERED -SHRA, AND/OR -DZ AND FG CONTINUE TO PERSIST ACROSS THE CWA THIS MORNING. BASED ON 12 UTC RAOBS, PROFILER/88D/SAT TRENDS COUPLED WITH RUC-20 ISENTROPIC AND Q (MIXING RATIO) ANALYSIS ALL INDICATE THE LIGHT AND SCATTERED PRECIP IS EXPECTED TO HOLD OVER THE REGION INTO THE AFTERNOON WITH THE CLOUD COVER HOLDING UNDER A STRENGTHENING INVERSION. WILL HAVE AN UPDATED ZFP OUT SHORTLY. 05 ...PREVIOUS MORNING AFD BELOW... VORT MAX MOVING ACROSS WIS THIS MORNING WITH BAND OF SHOWERS MOVING ACROSS THE GREAT LAKES. TAIL END OF THE SHOWERS MOVING ACROSS NE IL BUT SHOULD BE ALL BUT OVER BY DAYBREAK. WILL KEEP MENTION OF SHOWERS OVER NW IN AND CHANCE OF DRIZZLE ELSEWHERE INTO MID MORNING. OTHERWISE MOST OF THE DAY SHOULD BE DRY BUT CONTINUED OVERCAST. SOME THICKER FOG FORMING OVER NRN IA AND MN WHERE CLOUD DECK APPEARS TO HAVE CLEARED OR THINNED SUBSTANTIALLY IN SUBSIDENCE BEHIND DEPARTING VORT MAX. HOWEVER...IT LOOKS LIKE NRN IL AND IN SHOULD HAVE DEEP ENOUGH CLOUD COVER TODAY TO PREVENT ANY SIGNIFICANT FOG. VISIBILITIES WILL BE GENERALLY 4 TO 6 MILES SO WILL DROP FOG WORDING FROM FORECAST FOR NOW. NEXT WEAK DISTURBANCE TO MOVE ACROSS THE TOP OF THE RIDGE INTO THE GREAT LAKES TONIGHT. WILL HAVE SOME LIGHT RAIN AND DRIZZLE AGAIN TONIGHT...DRYING OUT THURSDAY MORNING. FINALLY MEX UPPER LOW TO LIFT OUT INTO IL BY FRI. THIS SHOULD BRING A SIGNIFICANT RAIN TO THE AREA AFTER MIDNIGHT THURSDAY NIGHT THROUGH THE DAY FRIDAY. FINALLY DRYING OUT SATURDAY AS WAVE CONTINUES LIFTING NE INTO GREAT LAKES. WILL KEEP FORECAST DRY THROUGH THE MIDDLE OF NEXT WEEK. MOS TEMPERATURES FOR TODAY CONTINUE TO RUN TOO WARM GIVEN THE EXTENT OF CLOUD COVER. WILL TEMPER TO LOWER 60S TODAY. WEAK COLD FRONT SLIPS THROUGH THURSDAY BUT NOT MUCH TEMPERATURE CHANGE EXPECTED. NOTICEABLY COOLER FRIDAY WITH EAST WINDS AND STEADY RAIN. STILL LOOKS LIKE STEADY OR SLOWLY RISING TEMPS LATE FRIDAY NIGHT INTO SATURDAY MORNING AS SURFACE LOW AND WARM FRONT LIFT THROUGH NRN IL. TURNING COOLER SAT AFTERNOON. SEASONABLY COOL AIRMASS SETTLES IN FOR EARLY NEXT WEEK. GFS INDICATES THAT COLD AIR MASS WAY UP IN NRN CANADA FINALLY GETS TAPPED MID WEEK. WILL HAVE TO WAIT AND SEE. && ALLSOPP .AVIATION DISCUSSION REGARDING 12Z TAFS... ONCE AGAIN TODAY CIGS WILL BE PRIMARY WX PROBLEM. UNSEASONABLY WARM AND MOIST AIR WILL CONTINUE TO MOVE ACRS AREA ON SWLY SFC FLOW THAT SHOULD RMN ARND 10 KTS THROUGH ABOUT 00Z. IFR CIGS HAVE MOVED ACRS TERMINALS IN WAKE OF WEAK MID LVL TROF THAT PRODUCED LGT SHWRS OVRNIGHT. EXPECT CIGS/VIS TO RMN IFR WITH OCNL BR/DZ TIL ARND 15Z WHEN DIURNAL SFC WARMING SHUD ALLOW CIGS TO BEGIN LIFTING INTO MVFR RANGE. LGT SWLY SFC FLOW TO CONT WELL INTO TNGT...AND WITH AMS AT OR NR SATURATION...IFR CONDS SHOULD REDEVELOP AGN LATER THIS EVENING. HOWEVER...BUILDING HI PRES OVR ONTARIO IS FCST TO PUSH A WEAK COLD FRONT THRU RGN AFT ABOUT 08Z TNGT. AS WINDS TURN WNWLY WITH FROPA...DRIER AMS IS FCST TO ADVECT IN AND SCOUR OUT LWR CLOUD DECK. MODELS IN FAIRLY CLOSE AGREEMENT IN BRINGING THIS FRONT THROUGH DURG 08-11Z TIME...WITH MAV OUTPUT ADVERTIZING MOST RSNBLE SCENARIO AS FAR AS CIGS ARE CONCERNED. MERZLOCK && .LOT...WATCHES/WARNINGS/ADVISORIES... .IL...NONE .IN...NONE .LK MI...NONE $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 700 PM EST WED NOV 17 2004 .AVIATION... DIFFICULT TERMINAL FORECASTS...KFWA CURRENTLY UP TO MVFR CIGS SHOULD SEE TREND TOWARD IFR/LIFR CIGS/VSBY TO FILL BACK IN LATER TONIGHT WITH SATURATED GROUND-950 MB LAYER PERSISTING AND WITH WIDESPREAD RA/DZ MUCH OF TODAY. 21Z RUC SOUNDINGS WITH STRENGTHENING INVERSION THROUGH 09Z AND WHILE ETA XSECTIONS DRY LOW LEVELS OUT RAPIDLY THURSDAY...HAVE ONLY SLOW IMPROVEMENT INDICATED THOUGH GIVEN INTIAL POOR CONDITIONS AND COL JUST TO OUR WEST THU AM SHOULD HELP TO LIMIT ANY RAPID MIX OUT. && .SHORT TERM... TONIGHT AND TOMORROW... THE WESTERN LOWER GREAT LAKES REGION IS CAUGHT BETWEEN BETWEEN A STRONG UPPER LEVEL RIDGE ANCHORED OVER THE LOWER MISSISSIPPI VALLEY AND A FAST MOVING WESTERLY FLOW ACROSS THE US/CANADIAN BORDER. THE RIDGE WILL BUILD IN FROM THE SOUTH TONIGHT TRAPPING MOISTURE FROM TODAY'S RAIN NEAR THE SURFACE RESULTING IN LOW CLOUDINESS AND FOG. A WEAK FRONT ASSOCIATED WITH THE SHORT WAVE MOVING ACROSS THE GREAT LAKES REGION WILL PUSH SOMEWHAT DRIER AIR ACROSS THE AREA ON THURSDAY. LITTLE TEMPERATURE CHANGE CAN BE EXPECTED WITH THIS FRONT. WARMER AIR WILL BEGIN ADVANCING NORTH AHEAD OF THE NEXT SYSTEM WHICH IS EXPECTED TO APPROACH FROM THE SOUTHWEST. MINOR CHANGES WERE MADE TO THE CURRENT FORECAST. RAISED LOW TEMPS A COUPLE OF DEGREES TOWARD THE WARMER MAV NUMBERS AND WITH SOMEWHAT DRIER CONDITIONS EXPECTED TOMORROW...RAISE HIGH TEMPERATURES A COUPLE OF DEGREES AS WELL...CLOSE TO THE MAV NUMBERS. ALSO INTRODUCED POPS LATE TOMORROW AFTERNOON OVER OUR FAR SOUTH COUNTIES IN AGREEMENT WITH ETA GUIDANCE. GFS WAS TOO AGGRESSIVE IN MOVING THE RAINFALL NORTH. && .LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY GFS AND DGEX IN GENERAL AGREEMENT WITH PATTERN AND TIMING SO COULD OPT TO A BLEND OF THE TWO. THIS IS IN GOOD AGREEMENT WITH THE ONGOING FORECAST...SO NO MAJOR CHANGES NEEDED...JUST TWEAKS. GENERAL THINKING IS LONG WAVE POSITIVELY TILTED TROUGH AT MID LEVELS OF THE ATMOSPHERE FROM HUDSON BAY TO NEVADA WILL MOVE EWD THROUGH THE WEEKEND...THEN NORTHWEST FLOW PATTERN SETTLES INTO THE AREA. THE SW FLOW PATTERN THE REST OF THIS WORK-WEEK AND BEGINNING OF THE WEEKEND WILL KEEP THE FORECAST WET AND MILD. ETA AND GFS IN GOOD AGREEMENT FOR A FEW RUNS ON THE TIMING AND STRENGTH OF THE SYSTEMS THAT WILL MOVE OVER THE AREA THURSDAY NIGHT THROUGH SATURDAY...THUS LEFT HIGH POPS ONGOING IN THE FORECAST. TEMPS THURSDAY NIGHT THROUGH SATURDAY NIGHT WL CONTINUE TO BE 10 TO 20 DEGREES ABOVE NORMAL...THEN AFTER POLAR FRONT MOVES THROUGH ON SUNDAY...TEMPS ABOUT 10 DEGREES BELOW NORMAL. GOOD SUBSIDENCE AND DRY AIR SHOULD BRING PRECIP TO AN END OVER MOST OF THE AREA SUNDAY THROUGH WEDNESDAY. THE QUESTION WILL BE NEAR LK MI WHERE GOOD TEMPERATURE DIFFERENTIALS BETWEEN THE RELATIVELY WARM LAKE AND COOLER AIR ALOFT WILL PROBABLY INDUCE LAKE PRECIP AND DEFINITELY WL GENERATE SOME CLOUDS. FORECAST WIND DIRECTION (280 DEGREES) LEADS TO UNFAVORABLE FETCH AND BAND PLACEMENT...SO WL NOT MENTION PRECIP ATTM. BY WEDNESDAY THE FETCH IS MUCH BETTER (330 DEGREES) SO MENTIONED A LOW PROB OF PRECIP NEAR THE LAKE. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. && $$ in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1230 PM EST WED NOV 17 2004 .AVIATION... A FAST MOVING SHORT WAVE OVER NORTHEAST MINNESOTA DEPICTED ON IR SATELLITE IMAGERY HAS MOVED QUICKLY INTO CENTRAL WISCONSIN SLOWING DOWN PROGRESS OF UPPER TROF PROLONGING SCATTERED RAIN SHOWERS ACROSS NORTHERN INDIANA. IFR CEILINGS AND VISIBILITY CONTINUE AT SOUTH BEND WITH WITH IFR VISIBILITY AND MVFR CEILINGS AT FORT WAYNE. CURRENT CONDITIONS WILL CONTINUE FOR THE REMAINDER OF THE AFTERNOON. UPPER TROF WILL BE EAST OF THE AREA BY TONIGHT ALLOWING SUBSIDENCE TO BUILD IN WITH BUILDING UPPER LEVEL RIDGE. THE SUBSIDENCE WILL CAUSE MOISTURE TO BE TRAPPED NEAR THE SURFACE. AS A RESULT...EXPECT IFR CONDITIONS TO DEVELOP AT BOTH SOUTH BEND AND FORT WAYNE LATER TONIGHT. && .UPDATE... LIGHT RAIN SHOWERS CONTINUE TO DEVELOP ACROSS NORTHEAST ILLINOIS THIS MORNING. UPPER TROF MOVING MORE SLOWLY THAN FORECAST. RUC MODEL HAS PICKED UP ON THIS TREND. SCATTERED PRECIP AND PATCHY FOG EXPECTED TO CONTINUE FOR MUCH OF THE DAY ACROSS THE FORECAST AREA. UPDATED FORECAST TO REFLECT THIS TREND. TEMPERATURE FORECAST CONTINUES TO BE ON TRACK AS MILD AIR CONTINUES TO STREAM UP AHEAD OF THE TROF AND WAS LEFT UNCHANGED. && .PREVIOUS DISCUSSION... SHORT TERM... SHARP SECONDARY UPR TROF NOW INTO ERN WI AIDING SHRA DVLPMNT FM SW MI BACK W INTO NRN IL ALG TAIL END OF UPR WV AND IN AREA OF DECENT LOW/MID LVL THETA ADVTN. BULK OF THIS LOOKS TO SWING ACRS NRN HALF OF CWA THIS MORNING ALTHOUGH NOT MUCH EXPECTED AS FOR MEASURABLE. SUBSIDENCE ALOFT AND TRAPPED BNDRY LYR MSTR WILL KEEP STRATUS LOCKED IN AGAIN TDA AND TONIGHT W/SRLY FLW REMAINING IN PLACE AND EVER INCREASING THERMAL RIDGING ALOFT. TIGHT LL THETA GRADIENT IN PLACE AGAIN OVERNIGHT WARRANTS CONTD MENTION OF DRIZZLE/FOG MENTION BUT HAVE NARROWED THAT WINDOW A BIT BASED ON TIMING OF BEST ISENTROPIC LIFT NR 06Z. OTHERWISE...MILD BUT GUIDANCE AS A WHOLE TOO WARM AGAIN THIS AFTN BUT BTR OVERNIGHT. && LONG TERM... THURSDAY THROUGH TUESDAY. SEVERAL CHANGES MADE TO BETTER REFLECT CURRENT MODEL TRENDS OVER THE PAST SEVERAL RUNS. THURSDAY LOOKS TO BE DRY AS DRYING TAKES PLACE IN THE LOWER LAYERS (AT LEAST BRIEFLY). HAVE BUMPED UP TEMPS ON THURSDAY TO SIMILAR READINGS EXPECTED FOR WEDS AS SEE NO REASON TO DEVIATE MUCH WITH LITTLE OVERALL CHANGE IN THERMAL PROFILE AND CLOUD COVERAGE. MODELS HAVE BEEN IN AGREEMENT ON PRECIPITATION MOVING INTO THE SW PART OF THE AREA SOMETIME THURS NGT. THE ONSET OF THE PRECIP APPEARS THE TRICKIEST PART OF THE FORECAST RIGHT NOW WITH SATURATED COLUMN LIKELY NOT OCCURRING TIL TOWARDS AM. WAS TEMPTED TO GO LIKELY POPS LATE THURS NGT...BUT WITH THIS CONCERN STILL THERE HAVE OPTED TO INCREASE TO 50 POPS IN SW AND EXTEND POPS TO NE OVERNIGHT TO BETTER MESH WITH SURROUNDING SITES. BASED ON GUIDANCE NUMBERS AND SEVERAL FACTORS IN MODELS (STRONG LIFT, DEEP MOISTURE, CPD'S DROPPING BELOW 10 MB, ETC) ALL POINTING TOWARDS NEED FOR CAT POPS ON FRIDAY. HAVE TRIED TO TREND SOMEWHAT WITH HIGHEST POPS INITIALLY SW IN THE AM THEN CAT POPS ALL AREAS FOR THE AFTERNOON. MAY NEED TO BE SOME ADJUSTMENTS IN TIMING IN LATER FORECASTS...BUT THIS LOOKS LIKE A GOOD START FOR NOW. FRI NGT WILL BE A BIT TRICKY AS MODELS SHOW MUCH OF THE LIFT TO THE NORTH...BUT WITH SFC LOW JUST TO THE WEST HAVE A HARD TIME WITH NO PRECIP (ALTHOUGH BEING IN THE WARM SECTOR OF THE STORM IT COULD BE ARGUED WE COULD END UP DRIER). HAVE WENT WITH LOW LIKELY POPS AFTER COLLABORATION. BEYOND FRI NGT...HAVE MADE NO CHANGES AS MAIN PUSH OF COLD AIR STILL SHOWING SIGNS OF SLOWER PROGRESSION (SUNDAY OR BEYOND). REGARDLESS...RETURN TO MORE FALL-LIKE/EARLY WINTER TEMPS LOOK TO BE IN THE OFFING. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. && $$ AVIATION...GLL SHORT TERM...HOLSTEN LONG TERM...FISHER UPDATE...GLL in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 925 AM EST WED NOV 17 2004 .UPDATE... LIGHT RAIN SHOWERS CONTINUE TO DEVELOP ACROSS NORTHEAST ILLINOIS THIS MORNING. UPPER TROF MOVING MORE SLOWLY THAN FORECAST. RUC MODEL HAS PICKED UP ON THIS TREND. SCATTERED PRECIP AND PATCHY FOG EXPECTED TO CONTINUE FOR MUCH OF THE DAY ACROSS THE FORECAST AREA. UPDATED FORECAST TO REFLECT THIS TREND. TEMPERATURE FORECAST CONTINUES TO BE ON TRACK AS MILD AIR CONTINUES TO STREAM UP AHEAD OF THE TROF AND WAS LEFT UNCHANGED. && .AVIATION/UPDATE... LEADING EDGE OF UPR TROF NOW INTO WRN MI ATTM W/AREAL COVERAGE OF SHRA ON THE WANE ALG TAIL END OF UPR VORT AXIS. LOOKS LIKE BULK OF ANY MEASURABLE WILL FALL N OF RTE 30 AND WILL CUT AM POPS AND TIMING BACK FURTHER. LACK OF SIG RAINFALL SHLD PRECLUDE MUCH FOR SIG FOG AND WILL DOWNPLAY IN 12Z TAF ISSUANCE. OTHERWISE...INCREASING LG SCALE SUBSIDENCE ALOFT BEHIND SYS HAS DUMPED CIGS UPSTREAM OVR IL/WI AND DOWNWARD SPIRAL ALREADY IN PROGRESS AT SBN. XPC IFR/LIFR AT SBN REMAINDER OF TDA AND GIVEN EARLY 09Z RUC INDICATIONS LTL IMPROVEMENT THIS AFTN. FWA CURRENT MVFR WILL QUICKLY DROP TO IFR AND LIFR AT TIMES BY MID MORNING AS UPR TROF AXIS AND ASSOCD/SUBSIDENCE PLUME SHARPEN AS WV CONTS TO TRANSLATE EWD ACRS MI THIS AM. && .PREVIOUS DISCUSSION... SHORT TERM... SHARP SECONDARY UPR TROF NOW INTO ERN WI AIDING SHRA DVLPMNT FM SW MI BACK W INTO NRN IL ALG TAIL END OF UPR WV AND IN AREA OF DECENT LOW/MID LVL THETA ADVTN. BULK OF THIS LOOKS TO SWING ACRS NRN HALF OF CWA THIS MORNING ALTHOUGH NOT MUCH EXPECTED AS FOR MEASURABLE. SUBSIDENCE ALOFT AND TRAPPED BNDRY LYR MSTR WILL KEEP STRATUS LOCKED IN AGAIN TDA AND TONIGHT W/SRLY FLW REMAINING IN PLACE AND EVER INCREASING THERMAL RIDGING ALOFT. TIGHT LL THETA GRADIENT IN PLACE AGAIN OVERNIGHT WARRANTS CONTD MENTION OF DRIZZLE/FOG MENTION BUT HAVE NARROWED THAT WINDOW A BIT BASED ON TIMING OF BEST ISENTROPIC LIFT NR 06Z. OTHERWISE...MILD BUT GUIDANCE AS A WHOLE TOO WARM AGAIN THIS AFTN BUT BTR OVERNIGHT. && LONG TERM... THURSDAY THROUGH TUESDAY. SEVERAL CHANGES MADE TO BETTER REFLECT CURRENT MODEL TRENDS OVER THE PAST SEVERAL RUNS. THURSDAY LOOKS TO BE DRY AS DRYING TAKES PLACE IN THE LOWER LAYERS (AT LEAST BRIEFLY). HAVE BUMPED UP TEMPS ON THURSDAY TO SIMILAR READINGS EXPECTED FOR WEDS AS SEE NO REASON TO DEVIATE MUCH WITH LITTLE OVERALL CHANGE IN THERMAL PROFILE AND CLOUD COVERAGE. MODELS HAVE BEEN IN AGREEMENT ON PRECIPITATION MOVING INTO THE SW PART OF THE AREA SOMETIME THURS NGT. THE ONSET OF THE PRECIP APPEARS THE TRICKIEST PART OF THE FORECAST RIGHT NOW WITH SATURATED COLUMN LIKELY NOT OCCURRING TIL TOWARDS AM. WAS TEMPTED TO GO LIKELY POPS LATE THURS NGT...BUT WITH THIS CONCERN STILL THERE HAVE OPTED TO INCREASE TO 50 POPS IN SW AND EXTEND POPS TO NE OVERNIGHT TO BETTER MESH WITH SURROUNDING SITES. BASED ON GUIDANCE NUMBERS AND SEVERAL FACTORS IN MODELS (STRONG LIFT, DEEP MOISTURE, CPD'S DROPPING BELOW 10 MB, ETC) ALL POINTING TOWARDS NEED FOR CAT POPS ON FRIDAY. HAVE TRIED TO TREND SOMEWHAT WITH HIGHEST POPS INITIALLY SW IN THE AM THEN CAT POPS ALL AREAS FOR THE AFTERNOON. MAY NEED TO BE SOME ADJUSTMENTS IN TIMING IN LATER FORECASTS...BUT THIS LOOKS LIKE A GOOD START FOR NOW. FRI NGT WILL BE A BIT TRICKY AS MODELS SHOW MUCH OF THE LIFT TO THE NORTH...BUT WITH SFC LOW JUST TO THE WEST HAVE A HARD TIME WITH NO PRECIP (ALTHOUGH BEING IN THE WARM SECTOR OF THE STORM IT COULD BE ARGUED WE COULD END UP DRIER). HAVE WENT WITH LOW LIKELY POPS AFTER COLLABORATION. BEYOND FRI NGT...HAVE MADE NO CHANGES AS MAIN PUSH OF COLD AIR STILL SHOWING SIGNS OF SLOWER PROGRESSION (SUNDAY OR BEYOND). REGARDLESS...RETURN TO MORE FALL-LIKE/EARLY WINTER TEMPS LOOK TO BE IN THE OFFING. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. && $$ AVIATION/SHORT TERM...HOLSTEN LONG TERM...FISHER UPDATE...GLL in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 515 AM EST WED NOV 17 2004 .AVIATION/UPDATE... LEADING EDGE OF UPR TROF NOW INTO WRN MI ATTM W/AREAL COVERAGE OF SHRA ON THE WANE ALG TAIL END OF UPR VORT AXIS. LOOKS LIKE BULK OF ANY MEASURABLE WILL FALL N OF RTE 30 AND WILL CUT AM POPS AND TIMING BACK FURTHER. LACK OF SIG RAINFALL SHLD PRECLUDE MUCH FOR SIG FOG AND WILL DOWNPLAY IN 12Z TAF ISSUANCE. OTHERWISE...INCREASING LG SCALE SUBSIDENCE ALOFT BEHIND SYS HAS DUMPED CIGS UPSTREAM OVR IL/WI AND DOWNWARD SPIRAL ALREADY IN PROGRESS AT SBN. XPC IFR/LIFR AT SBN REMAINDER OF TDA AND GIVEN EARLY 09Z RUC INDICATIONS LTL IMPROVEMENT THIS AFTN. FWA CURRENT MVFR WILL QUICKLY DROP TO IFR AND LIFR AT TIMES BY MID MORNING AS UPR TROF AXIS AND ASSOCD/SUBSIDENCE PLUME SHARPEN AS WV CONTS TO TRANSLATE EWD ACRS MI THIS AM. && .SHORT TERM... SHARP SECONDARY UPR TROF NOW INTO ERN WI AIDING SHRA DVLPMNT FM SW MI BACK W INTO NRN IL ALG TAIL END OF UPR WV AND IN AREA OF DECENT LOW/MID LVL THETA ADVTN. BULK OF THIS LOOKS TO SWING ACRS NRN HALF OF CWA THIS MORNING ALTHOUGH NOT MUCH EXPECTED AS FOR MEASURABLE. SUBSIDENCE ALOFT AND TRAPPED BNDRY LYR MSTR WILL KEEP STRATUS LOCKED IN AGAIN TDA AND TONIGHT W/SRLY FLW REMAINING IN PLACE AND EVER INCREASING THERMAL RIDGING ALOFT. TIGHT LL THETA GRADIENT IN PLACE AGAIN OVERNIGHT WARRANTS CONTD MENTION OF DRIZZLE/FOG MENTION BUT HAVE NARROWED THAT WINDOW A BIT BASED ON TIMING OF BEST ISENTROPIC LIFT NR 06Z. OTHERWISE...MILD BUT GUIDANCE AS A WHOLE TOO WARM AGAIN THIS AFTN BUT BTR OVERNIGHT. && .LONG TERM... THURSDAY THROUGH TUESDAY. SEVERAL CHANGES MADE TO BETTER REFLECT CURRENT MODEL TRENDS OVER THE PAST SEVERAL RUNS. THURSDAY LOOKS TO BE DRY AS DRYING TAKES PLACE IN THE LOWER LAYERS (AT LEAST BRIEFLY). HAVE BUMPED UP TEMPS ON THURSDAY TO SIMILAR READINGS EXPECTED FOR WEDS AS SEE NO REASON TO DEVIATE MUCH WITH LITTLE OVERALL CHANGE IN THERMAL PROFILE AND CLOUD COVERAGE. MODELS HAVE BEEN IN AGREEMENT ON PRECIPITATION MOVING INTO THE SW PART OF THE AREA SOMETIME THURS NGT. THE ONSET OF THE PRECIP APPEARS THE TRICKIEST PART OF THE FORECAST RIGHT NOW WITH SATURATED COLUMN LIKELY NOT OCCURRING TIL TOWARDS AM. WAS TEMPTED TO GO LIKELY POPS LATE THURS NGT...BUT WITH THIS CONCERN STILL THERE HAVE OPTED TO INCREASE TO 50 POPS IN SW AND EXTEND POPS TO NE OVERNIGHT TO BETTER MESH WITH SURROUNDING SITES. BASED ON GUIDANCE NUMBERS AND SEVERAL FACTORS IN MODELS (STRONG LIFT, DEEP MOISTURE, CPD'S DROPPING BELOW 10 MB, ETC) ALL POINTING TOWARDS NEED FOR CAT POPS ON FRIDAY. HAVE TRIED TO TREND SOMEWHAT WITH HIGHEST POPS INITIALLY SW IN THE AM THEN CAT POPS ALL AREAS FOR THE AFTERNOON. MAY NEED TO BE SOME ADJUSTMENTS IN TIMING IN LATER FORECASTS...BUT THIS LOOKS LIKE A GOOD START FOR NOW. FRI NGT WILL BE A BIT TRICKY AS MODELS SHOW MUCH OF THE LIFT TO THE NORTH...BUT WITH SFC LOW JUST TO THE WEST HAVE A HARD TIME WITH NO PRECIP (ALTHOUGH BEING IN THE WARM SECTOR OF THE STORM IT COULD BE ARGUED WE COULD END UP DRIER). HAVE WENT WITH LOW LIKELY POPS AFTER COLLABORATION. BEYOND FRI NGT...HAVE MADE NO CHANGES AS MAIN PUSH OF COLD AIR STILL SHOWING SIGNS OF SLOWER PROGRESSION (SUNDAY OR BEYOND). REGARDLESS...RETURN TO MORE FALL-LIKE/EARLY WINTER TEMPS LOOK TO BE IN THE OFFING. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. && $$ AVIATION/SHORT TERM...HOLSTEN LONG TERM...FISHER in AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE WICHITA KS 1049 AM CST WED NOV 17 2004 LATEST SATELLITE LOOP SHOWING QUITE A BIT OF SUN PEAKING OUT ACROSS SOUTHEAST KANSAS. THIS TREND SHOULD CONTINUE THROUGH MOST OF THE DAY WITH SOME PERIODIC CIRRUS SHIELDS MOVING OVERHEAD. OTHERWISE, I WOULD EXPECT NUMEROUS SHOWERS TO DEVELOP ACROSS HARPER AND KINGMAN COUNTIES THIS AFTERNOON AND SPREAD EAST AS THE AFTERNOON PROGRESSES. THIS IS IN RESPONSE TO THE UPPER LEVEL COLD POCKET PIVOTING THROUGH NORTHERN TEXAS. THIS COLD POCKET WILL CAUSE THE THETA SURFACES TO RISE THIS AFTERNOON, WHICH WILL INDUCE LIFT. RUC SOUNDINGS SHOWING THINGS NEARLY MOIST ADIABATIC WITH WEAK SYMMETRIC STABILITY. AS A RESULT, WE COULD SEE SOME MODERATE SHOWERS. COX -------------------------------------------------------------------- 413 AM CST WED NOV 17 2004 .PREVIOUS DISCUSSION... TODAY-TONIGHT: BASED ON LATEST WATER VAPOR LOOP AND 00 COORDINATED UNIVERSAL TIME UPPER AIR ANALYSIS...APPEARS THAT SOUTHWESTERN US UPPER LOW IS FINALLY ON THE MOVE. POSITIVE TILT WAVE WILL SPREAD INCREASING UPPER DIVERGENCE OVER THE FORECAST AREA LATER TODAY AND INCREASING THIS EVENING. PROBLEM AGAIN IS CATEGORICAL MODEL OUTPUT STATISTICS PROBABILITY OF PRECIPITATION, GIVEN WHAT APPEARS TO BE A LIGHT PRECIPITATION EVENT. SOME DRIER AIR SHOULD ADVECT INTO SOUTHEAST KS SO TAPERED PROBABILITY OF PRECIPITATION OFF TO THE EAST. THU: SECOND SPEED MAXIMUM WILL APPROACH AREA THU NIGHT, WITH ENTIRE FORECAST AREA IN LEFT EXIT REGION. ASSOCIATED SHORTWAVE WILL MOVE THROUGH DURING THE DAY FRI. MAIN CONCERN OVERNIGHT IS WHERE BEST CHANCE OF RAIN WILL OCCUR, WITH GLOBAL FORECAST SYSTEM MODEL KEEPING 700 MILLIBAR CIRCULATION FURTHER SOUTH, RESULTING BACKED FLOW. HIGHER DEWPOINTS IN SOUTHEAST KS SHOULD KEEP MINIMUMS ON THE MILD SIDE FOR ANOTHER NIGHT, WHILE COLD AIR ADVECTION SPILLS DOWN WESTERN EDGE OF FORECAST AREA. FRI-FRI NIGHT: DRIER 700 MILLIBAR AIR SHOULD LIMIT PRECIPITATION DURING THE DAY FRI...MAINLY IN THE EAST/NORTHEAST SECTIONS. SAT-SUN: NEXT SHORTWAVE ROTATES OUT OF REDEVELOPING WESTERN US TROUGH. INCREASING CYCLOGENESIS WILL INDUCE SUBSTANTIAL MIDLEVEL WARM AIR ADVECTION BY 00 COORDINATED UNIVERSAL TIME SUN. FOCUS ON RAIN/SNOW LINE BECOMES AN ISSUE, WITH TRENDS CONTINUE TO SUGGEST MIX POSSIBLE IN CENTRAL KS DURING THE DAY, SPREADING OVER MUCH OF THE FORECAST AREA SAT NIGHT. HOWEVER APPEARS BOTH EUROPEAN CENTRE FOR MEDIUM RANGE WEATHER FORECASTS MODEL/GLOBAL FORECAST SYSTEM MODEL SHUT DOWN PRECIPITATION RATHER QUICKLY BY SUN MORNING. THIS COULD BE PROBLEMATIC EAST OF ICT FOR PRECIPITATION TYPE. SUN NIGHT-TUE: REPRIEVE ON SUN IS BRIEF. TRENDING TOWARD COMPROMISE WITH EUROPEAN CENTRE FOR MEDIUM RANGE WEATHER FORECASTS MODEL FASTER THAN THE GLOBAL FORECAST SYSTEM MODEL. THE MAIN IMPACT ON THE EUROPEAN CENTRE FOR MEDIUM RANGE WEATHER FORECASTS MODEL ORIENTATION OF LONGWAVE IS PRECIPITATION TIMING. BOTH MODELS SUGGEST MOSTLY SOLID PRECIPITATION DEVELOPING EITHER SUN NIGHT OR MON. THE EUROPEAN CENTRE FOR MEDIUM RANGE WEATHER FORECASTS MODEL STARTS A BIT DRIER IN THE LOW LEVELS, WHICH MAY DELAY PRECIPITATION ONSET UNTIL CLOSER TO 06 COORDINATED UNIVERSAL TIME MON. EUROPEAN CENTRE FOR MEDIUM RANGE WEATHER FORECASTS MODEL WITH A FASTER/NORTHERLY TRACK IMPLIES MUCH BETTER CHANCE OF PRECIPITATION, COMPARED TO SLOWER/SOUTHERLY TRACK OF GLOBAL FORECAST SYSTEM MODEL. AT THIS POINT WILL NEED TO INTRO AT LEAST SMALL CHANCES OF PRECIPITATION MON AND MON NIGHT. GIVEN DIFFICULTY OF FORECASTING PRECIPITATION TYPE, WILL GO PRIMARILY WITH RAIN OR SNOW COMBINATION FOR NOW. && .PRELIMINARY POINT TEMPERATURES/PROBABILITY OF PRECIPITATION... WICHITA-KICT 65 57 59 47 / 50 80 80 60 HUTCHINSON 64 57 58 44 / 60 80 80 70 NEWTON 65 57 59 47 / 50 80 80 70 ELDORADO 66 58 60 48 / 40 70 80 60 WINFIELD-KWLD 66 58 61 49 / 50 70 80 50 RUSSELL 62 52 52 40 / 60 90 80 70 GREAT BEND 62 53 53 40 / 70 80 80 70 SALINA 65 56 56 45 / 40 80 80 70 MCPHERSON 65 56 57 45 / 50 80 80 70 COFFEYVILLE 69 58 64 52 / 20 70 70 60 CHANUTE 68 58 63 51 / 20 70 80 60 IOLA 68 58 62 51 / 20 60 80 60 && .ICT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ 17/HOWERTON ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 924 PM EST WED NOV 17 2004 RADAR IMAGERY SHOWS SCT -SHRAS W OF THE BLUE RIDGE WITH -RA BEING REPORTED AT CUMBERLAND AND PETERSBURG WV. NEW ETA COMING IN AND SUGGESTS AREA OF RAIN WILL STAY MAINLY SOUTH OF THE POTOMAC RIVER WITH BEST CHANCE FOR RAIN SOUTH OF FAUQUIER CTY TO CHO. INCREASED POPS IN THE WEST AND THE SHEN VALLEY AND FOOTHILLS BASED ON RADAR TRENDS AND NEW MODEL GUIDANCE. SCT -SHRAS FCST TO EXIT THE FCST AREA AROUND 09Z PER 00Z ETA/RUC GUIDANCE. ROSA PREVIOUS AFD... .SHORT TERM (TONIGHT THROUGH THURSDAY): WATER VAPOR LOOP SHOWS A RIDGE CONTINUES TO DOMINATE THE EAST CENTRAL CONUS...WITH A TROUGH OVER THE WESTERN ATLANTIC WATERS. A SHORTWAVE LOCATED ACROSS THE CENTRAL GREAT LAKES IS ROTATING AROUND THE RIDGE....WHILE THE PRIMARY WAVE ACROSS THE SOUTHWEST CONUS BEGINS TO EJECT NORTHEAST ACROSS WESTERN TEXAS. ACARS 400-250MB WIND OBSERVATIONS REVEAL A 70-80KT NORTHWESTERLY JET ACROSS THE WEST CENTRAL GREAT LAKES REGION ASSOCIATED WITH THE UPSTREAM WAVE. 12Z SURFACE ANALYSIS PLACES A 1029MB ANTICYCLONE OVER THE APPALACHIANS. A BACKDOOR COLD FRONT IS MOVING SOUTHWEST ACROSS NEW ENGLAND...WHILE WARM ADVECTION IS OCCURRING ACROSS THE MIDWEST AHEAD OF A STALLING BOUNDARY. EROSION OF MIDLEVEL CLOUDS WAS UNEXPECTED THIS AFTERNOON...AS MORNING RAOBS AND ACARS SOUNDINGS SHOWED A STRONG SUBSISTENT INVERSION AT 8KFT. THE CLOUD LAYER WAS QUITE THIN...AND PERHAPS TURBULENT DIURNAL AND EDDY MIXING TRANSPORTED ENOUGH DRY AIR UPWARD TO MIX OUT THIS CLOUD LAYER. LOCAL ACARS SOUNDINGS DURING THE EARLY AFTERNOON INDICATE THAT THIS SUBSISTENT INVERSION HAS LOWERED TO 6KFT. WITH THE WAVE APPROACHING THIS EVENING...ANTICIPATE A GREATER AMOUNT OF MOISTURE WHICH WILL BE TRAPPED AT THE INVERSION LEVEL...AND HENCE INCREASING CLOUDS. BOTH 12Z GFS/ETA BUFKIT FORECAST SOUNDINGS SHOW THIS INVERSION CONTINUES TO LOWER OVERNIGHT AS MOISTURE INCREASES. NOT AS IMPRESSED WITH THE DYNAMICS OF THIS WAVE (MUCH WEAKER UPPER LEVEL JET THAN THE LAST). HOWEVER...PRESENCE OF INCREASING MOISTURE FROM THE MIDWEST SHOULD COMPENSATE...ALLOWING SOME LIGHT PRECIPITATION TO DEVELOP OVER PORTIONS OF THE FORECAST AREA OVERNIGHT. THE COMBINATION OF INCREASING MOISTURE AND CLOUD COVER WILL LEAD TO A WARMER NIGHT THAN LAST. WINDS WILL REMAIN LIGHT. THE SHORTWAVE WILL PASS SOUTHEAST THROUGH THE AREA LATE TONIGHT...LEAVING THE REGION WITH ADDITIONAL WARMING AND SUBSIDENCE ALOFT THURSDAY. THIS SHOULD ACT TO TRAP RESIDUAL LOW LEVEL MOISTURE AS A STRATUS LAYER. UPSLOPE SHOULD ALLOW FOR SOME LIMITED LIGHT PRECIPITATION ACROSS THE MOUNTAINS EARLY IN THE MORNING...BEFORE SUBSIDENCE ALOFT LIMITS THE DEPTH OF SATURATION DURING THE AFTERNOON. DESPITE MODELS DEPICTING WARMING IN THE LOWER LEVELS ACROSS THE REGION FROM THE MIDWEST TOMORROW...HAVE TRENDED COOLER THAN MOS HIGH TEMPERATURE FORECASTS DUE ANTICIPATED TRAPPED STRATUS CLOUD LAYER. LIGHT WINDS ARE ONCE AGAIN EXPECTED. && .AVIATION: WITH THE LOWERING INVERSION AND MOISTENING FROM AN APPROACHING SHORTWAVE...EXPECT MID LEVEL CLOUDS TO REDEVELOP THIS EVENING. AS THE INVERSION CONTINUES TO LOWER...ANTICIPATE A LOWER STRATUS DECK TO DEVELOP OVERNIGHT...WHILE WINDS BECOME CALM. LEFT MENTION OF PRECIPITATION OUT OF TERMINALS AS COVERAGE AND TIMING QUESTIONS REMAIN...WHILE PRECIPITATION SHOULD REMAIN LIGHT. THEREFORE...ONLY ANTICIPATE MVFR VISIBILITIES WITHIN SHOWERS TO MATCH MVFR CEILINGS. && .LONG TERM... BASIC RDG PTTN MAINTAINED THU NGT. WK SFC CDFNT SAGS INTO CWFA...W/O DYNAMICS OR MSTR. WAA...AND ASSOC PCPN...EVIDENT TO THE W...ALONG THIS SAME BNDRY. DONT THINK MSTR WL BE THICK ENUF TO MAKE IT OVR APLCHNS THO. SINCE NO OTR FORCING MECH WL BE PRESENT...WL GO LWR THAN MOS FOR POPS. WL KEEP SCHC FOR WRN CNTYS...WHERE SUPPORT WL BE THE BEST. WAA BEGINS IN EARNEST FRI...TIL WM FROPA SAT. W/ UPR FLOW FM GLFMEX...MSTR SUPPLY SHUD BE AMPLE. ONLY QSTN WUD BE DURATION. DO NOT ANTICIPATE A RAINOUT...BUT UPGLIDE GUD ENUF FOR LOTSA CLDS AND CHC POPS THRUOUT. ALSO MADE MOSTLY SMALL CHGS TO TEMP FCST IN THIS PD...MOSTLY UPWD GIVEN LACK OF ANY COLD AIR. SAT MRNG MIN-T REFLECTS THE MOST DRASTIC ADJUSTMENT DUE TO CLDS AND WAA. IF WMFNT ENDS UP BEING SLOWER OR PCPN MORE WIDESPREAD...THESE TEMPS CUD BE A PINCH TOO HIGH. ALL TEMPS WL BE ABV CLIMO AVGS. BAROCLINIC ZN SHUD KICK N BY SUN...IN TIME FOR CDFNT APPCHG FM THE W. UPR FLOW SOMEWHAT FLAT BY THEN. JETMAX WL BE ACRS CNTRL CONUS... IN STEEPENING POS TILT TROF. EFFECT ON E COAST WL BE LACK OF A KICKER TO CLEAR FRONT OUT. WL KEEP POPS GOING THRU SUN. HWVR... THRAFTR CDFNT SHUD SAG FAR ENUF TO THE S TO ALLW FOR SOME DRIER AIR...IN THE FORM OF A SFC HIGH...TO WORK EWD. GRIDS WL REFLECT A DRYING TREND MON...AND DRY CONDS TUE-WED. WL KEEP ANY POTL LOPRES DVLPMNT ALNG STALLED FNT TO OUR S W/ THIS PKG GIVEN RNG OF UNCERTAINTY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SHORT TERM/AVIATION FORECASTER: ROGOWSKI LONG TERM FORECASTER: HTS md AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1130 AM EST WED NOV 17 2004 .UPDATE... STRONG SHORTWAVE OVER MICHIGAN SHOWING UP VERY NICELY ON THE WATER VAPOR LOOP THIS MORNING. IR SATELLITE REVEALING SOME CONVECTIVE CLOUD TOPS OVER EXTREME SOUTHEAST LOWER MICHIGAN AT 11AM. THIS HAS LED TO SOME POCKETS OF BRIEF HEAVY RAIN AROUND THE DETROIT METRO AREA THIS MORNING...ALTHOUGH NO LIGHTNING STRIKES HAVE BEEN DETECTED THUS FAR. THIS IS ALL MOVING FAIRLY QUICKLY OUT OF THE REGION AS THE SHORTWAVE CONTINUES TO MOVE EAST THROUGH THE AREA. MAIN WEATHER THIS AFTERNOON WILL BE LOW CEILINGS AND LOW VISIBILITIES. LARGE AREA OF 200 TO 700 FEET STRATUS HAS SET UP IN THE WAKE OF SHORTWAVE. THIS WILL BE THE CASE FOR THE REST OF THE AFTERNOON AS SUBSIDENCE REGION OF WAVE SETS UP OVER SOUTHEAST LOWER MICHIGAN. WARM AIR ADVECTION AT 850 MBS IS STRENGTHENING INVERSION AND TRAPPING STRATUS BENEATH IT. DEEP LAYER MOISTURE AS EVIDENT ON 12Z DTX SOUNDING...ALONG WITH WARM AIR ADVECTION...IS AND WILL CONTINUE TO KEEP VISIBILITIES IN THE 1 TO 3 MILE RANGE THROUGH THE AFTERNOON. STRONGER SUBSIDENCE WILL BUILD IN FORCING CONVECTION OFF TO OUR EAST...THUS BRINGING AN END TO WIDESPREAD RAIN SHOWERS BY NOON...WITH PATCHY DRIZZLE TAKING OVER FOR THE AFTERNOON. THUS WILL WAIT UNTIL AROUND NOON TO RESEND THE ZONES IN ORDER TO FRESHEN UP WORDING FOR THE REMAINDER OF THE DAY. FOR NOW WILL LEAVE TEMPS AS IS...BUT CURRENT TRENDS SUGGEST WE MAY BE A FEW DEGREES LOWER THAN THE FORECAST MAXES OF 57. WILL TAKE ANOTHER LOOK AT THIS BEFORE SENDING OUT UPDATED ZONES TO DETERMINE IF MAX TEMP ADJUSTMENTS NEED TO BE MADE. $$ SHULER .PREVIOUS DISCUSSION ISSUED AT 300 AM THIS MORNING... WATER VAPOR LOOP THIS MORNING IS QUITE IMPRESSIVE WITH POTENT SHORT WAVE ACROSS WISCONSIN (06Z) WITH STRONG DPVA AND EXCELLENT DIVERGENCE SIGNATURE PER UPSTREAM PROFILERS. CLOUD TOPS HAVE COOLED SIGNIFICANTLY THIS MORNING AND THERE IS SOME CONCERN FOR SOME THUNDER THIS MORNING. OTHERWISE, EXTENSIVE AREA OF DRIZZLE AND FOG WILL PROGRESS TOWARD SHOWERS AND INCREASE ACROSS THE REGION THIS MORNING AS THE WAVE APPROACHES. MEANWHILE, OUR PREVIOUSLY CLOSED UPPER LOW ACROSS BAJA CALIFORNIA HAS FINALLY OPENED UP AND BECOME MORE NEGATIVE TILTED WITH AN EXTENSIVE AREA OF CONVECTION FROM THE WESTERN GULF OF MEXICO INTO TEXAS. THIS WILL BE OUR MAIN WEATHER PLAYER INTO FRIDAY. AT THE SURFACE, ILL-DEFINED HIGH OVER THE EAST COAST AND COLD FRONT APPROACHING THE NORTH DAKOTA/NORTHERN MINNESOTA HAS RESULTED IN OUR WARM ADVECTION REGIME WITH UPSTREAM DEWPOINTS WELL INTO THE 50S (EVEN SOME 60S JUST SOUTH OF I-80 IN IOWA). UNTIL WE ARE ABLE TO MOVE THE FRONT SOUTH OF THE REGION, WE WILL CONTINUE MOIST AND WARM. TODAY... 06Z RUC BRINGS THIS STRONG SHORT WAVE ACROSS THE STATE TODAY WITH MAIN DPVA AND Q-VECTOR CONVERGENCE LIFT DURING THIS MORNING. AS PREVIOUSLY MENTIONED, SOME CONCERN WITH AN ISOLATED LIGHTNING STRIKE AS VERTICAL TOTALS CLIMB INTO THE 23C RANGE AND CROSS SECTIONS SHOW A LAYER OF NEGATIVE EPV BETWEEN 700-500MB WHERE THE STRONGEST LIFT/OMEGA WILL OCCUR NEAR 15Z. WITH NO INDICATIONS OF LIGHTNING STRIKES UPSTREAM THUS FAR, WE WILL KEEP IT OUT FOR NOW. THIS WILL BE A FAST MOVING EVENT WITH REGION OF STRONG SUBSIDENCE BEHIND THIS WAVE DURING THE AFTERNOON. STILL AMPLE MOISTURE TO BE HAD AS SYSTEM HAD TIME TO TAP INTO PRECIP WATERS IN EXCESS OF 1"(300% OF NORMAL) AND WILL CONTINUE WITH THE CHANCE OF SOME LIGHT RAIN SHOWERS/DRIZZLE THIS AFTERNOON. TEMPERATURES TODAY SHOULD REMAIN UNIFORM ACROSS THE REGION (AS HAS BEEN THE CASE THE PAST 24 HOURS) WITH TRAJECTORIES POINTING TOWARD HIGHS AROUND 57F. TONIGHT... A UNIQUE CHALLENGE WITH ADDITIONAL PRECIP CHANCES ACROSS THE FAR SOUTHERN COUNTIES. THE GFS DEVELOPS A REGION OF FGEN ACROSS CHICAGO THEN TRACKS THIS PRECIP EAST OVERNIGHT. THE ETA ALSO SUGGESTS THIS BUT FURTHER SOUTH. WE WOULD HAVE TO FAVOR THE ETA WITH THIS ONE...BUT IT WILL BE CLOSE. THE REASON IS WITH SUCH A STRONG DEPARTING WAVE, REGION OF SUBSIDENCE AND HEIGHT RISES WOULD SUPPRESS PRECIP BAND SOUTH AND THERMAL GRADIENT IN THE 850-700 LAYER DOES NOT APPEAR THAT GREAT TO SUPPORT THE GFS IDEA. HOWEVER, SOUNDINGS DO HAVE A VERY MOIST LOW LEVELS AND AS THE UPSTREAM COLD FRONT APPROACHES (MORE LIKE A COOL FRONT), ENOUGH BOUNDARY LAYER CONVERGENCE AND SHEAR IN THE PROFILES FOR MORE DRIZZLE AND FOG TONIGHT. WITH DEWPOINTS UPSTREAM STILL IN THE 50S, WOULD EXPECT LOW TEMPS TONIGHT TO REMAIN INTO THE 50S FOR MOST OF THE CWA. THURSDAY... THE AFOREMENTIONED WEAK COOL FRONT IS EXPECTED TO BE EAST/SOUTHEAST OF THE STATE DURING THE AFTERNOON. MEANWHILE, SOUTHERN WAVE BEGINS TO LIFT FURTHER NORTH TOWARD THE MID MISSISSIPPI RIVER VALLEY LATE IN THE DAY. WHILE MID LEVELS OF THE ATMOSPHERE DRY OUT (900-600MBS) PER THE GFS/ETA SOUNDINGS, WE WILL HAVE PLENTY OF HIGHER LEVEL MOISTURE ABOVE TO KEEP WITH A MOSTLY CLOUDY FORECAST. TEMPERATURES WILL BE A BIT DIFFICULT WITH NEW MACHINE NUMBERS CLIMBING INTO THE 60S. WE WOULD PREFER TO KEEP IT MORE CONSERVATIVE WITH A BIT LOWER 1000-850MB THICKNESS AND PLENTY OF CLOUD COVER. THURSDAY NIGHT INTO FRIDAY... MODEL CONSENSUS BRINGS THIS UPPER WAVE FURTHER NORTH AS SURFACE HIGH ATTEMPTS TO BUILD ACROSS LAKE SUPERIOR. THIS WILL INCREASE THE THETA-E GRADIENT FURTHER UPSTREAM WITH IMPRESSIVE ISENTROPIC ASCENT ON FRIDAY. WITH SOMEWHAT DRIER AIR FILTERING SOUTH THURSDAY NIGHT, WE WILL REMOVE THE FOG/DRIZZLE AND KEEP ANY RAIN SOUTH OF THE STATE LINE. THIS WILL CHANGE QUICKLY ON FRIDAY BUT AS IS USUALLY THE CASE, NORTHEAST-EAST FLOW WILL KEEP THE LOWER LAYERS DRY BELOW 800MBS. IT MIGHT TAKE A BETTER PART OF THE MORNING FROM SOUTH TO NORTH BEFORE WE SEE MEASURABLE PRECIP. THEN WITH PRECIPITABLE WATERS IN EXCESS OF 1", NEEDLESS TO SAY IT WILL RAIN. TEMPERATURES WILL NOT MOVE A WHOLE LOT WITH WET BULBING BRINGS HIGHS AROUND 50F. FRIDAY NIGHT... THE BULK OF THE LIFT WILL CONTINUE TO TRACK NORTH EARLY IN THE EVENING BUT WITH PLENTY OF GULF OF MEXICO MOISTURE IN PLACE, WE SHOULD CONTINUE TO OBSERVE OCCASIONAL LIGHT RAIN. WITH ANOTHER SURGE OF HIGHER DEWPOINTS ADVECTING NORTH OVERNIGHT, MORE ADVECTION TYPE FOG SHOULD BE THE RESULT. NOW ONTO THE EXTENDED AS RECENT MODEL TRENDS ARE FAVORING A LESS THAN AGGRESSIVE COLD BLAST EARLY NEXT WEEK. PACIFIC RIDGE REMAINS MORE NARROW AS YET ANOTHER STRONG JET COMES OFF CHINA AND PINCHES THE RIDGE. THIS WILL SET UP AN ELONGATED POSITIVE TILTED TROF INTO EARLY NEXT WEEK AND THIS SHOULD ALLOW FOR A SLOWER INFLUX OF SEASONABLE TEMPERATURES THE WEEK OF THANKSGIVING. && .DTX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ BGM EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ALBANY NY 1002 AM EST WED NOV 17 2004 .SHORT TERM (REST OF TODAY)... AT 1500 UTC...SFC HIGH PRESSURE OVER THE VIRGINIAS WILL DOMINATE THE WEATHER TODAY ACROSS THE FCST AREA...BUT WITH QUITE A BIT OF CLOUDINESS. SEVERAL WEAK H500 IMPULSES CONTINUE TO ZIP ALONG THE ERN FLANK OF THE H500 RIDGE CENTERED OVER THE ERN GREAT LAKES AND OHIO VALLEY. THESE WEAK SHORT WAVES ARE CAPTURED WELL BY THE 40-KM RUC. UPPED THE CLOUDINESS BASED UPON THE VISIBLE SATELLITE PICTURE OVER THE PAST COUPLE OF HOURS AND THE 1200 UTC KALY SOUNDING...WHERE MOISTURE SEEMS TO BE TRAPPED UNDER INVERSION AT AROUND 775 HPA (6KF-8KFT). ALSO...I LOWERED TEMPS BY 2-4 DEGREES OVER THE ENTIRE FCST AREA DUE TO THE INCREASED CLOUD COVER. THE SOUTHEASTERN CATSKILLS AND MID HUDSON VALLEY WILL HAVE SOME SUNSHINE PRIOR TO NOON...SO WILL PHRASE AS MOSTLY CLOUDY THERE THIS AFTERNOON. .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NY...NONE. VT...NONE. && .PREVIOUS DISCUSSION... THE FOLLOWING WAS ORIGINALLY ISSUED AT 345 AM... .SYNOPSIS... CURRENTLY LARGE UPPER LEVEL RIDGE DOMINATING THE CENTRAL AND EASTERN PORTIONS OF THE COUNTRY. SEVERAL SHORTWAVES MOVING THEIR WAY EAST-SOUTHEASTWARD THROUGH THE NORTHERN OHIO VALLEY AND THE SECOND WEAKER ONE WILL EFFECT CWA ON THURSDAY AFTERNOON INTO THE EVENING WITH JUST A CHANCE OF SCATTERED RAIN SHOWERS. TREND WILL BE FOR INCREASING CLOUDS AND ABOVE AVERAGE TEMPERATURES FOR THE SHORT TERM. && .SHORT TERM (WEDNESDAY THROUGH THURSDAY NIGHT)... WEDNESDAY WILL SEE INCREASING CLOUDINESS ALONG WITH LIGHT AND VARIABLE WINDS. WITH MOSTLY CLOUDY SKIES AND LITTLE MIXING HIGH TEMPS EXPECTED TO BE SLIGHTLY COOLER THAN TUESDAYS. SHORTWAVE MOVES INTO FAR WESTERN NY AND WESTERN PA BY 6Z THURSDAY. NORTHWESTERLY UPPER LEVEL FLOW OVER CWA ASSOCIATED WITH THE EASTERN BOUNDARY OF RIDGE WILL DEFLECT THIS WEAK SYSTEM TO SOUTH AND WEST. HOWEVER WAA BRINGING WARMER TEMPS FOR THURSDAY AND MOSTLY CLOUDY SKIES. KEEPING POPS LIMITED TO CHANCE SHOWERS AFTER 12Z WITH BEST CHANCE OF SHOWERS THURSDAY EVENING. GFS THICKNESS FOR ALL LOWER LEVELS UP TO 500MB TOO WARM FOR SNOW...SHOWERS SHOULD REMAIN ALL RAIN FOR THE OVERNIGHT PERIOD. PRECIPITATION ONLY A FEW HUNDREDTHS OF AN INCH. && .EXTENDED (FRIDAY THROUGH TUESDAY)... FLOW BECOMING MORE WESTERLY AS UPPER LEVEL RIDGE BREAKS DOWN. FRIDAY STAYING PARTLY CLOUDY AND DRY. NEXT SYSTEM MOVES IN ON SATURDAY WITH THE PASSAGE OF A WARM FRONT. LATEST MODEL RUNS SHOWING PRECIP MOVING IN EARLIER THAN PREVIOUS RUNS. ETA80 SHOWS LEADING EDGE OF PRECIP AS EARLY AS 18Z SATURDAY...WITH GFS SLOWER TO MOVE PRECIP IN. WILL PUT OUT CHANCE SHOWERS FOR SATURDAY AFTERNOON AND SATURDAY EVENING. BASED ON THICKNESS ANALYSIS AND MODEL SOUNDINGS DROPPED SNOW IN FORECAST. TREND FOR SUNDAY INTO THE EARLY PART OF NEXT WEEK IS FOR CHANCE RAIN AND EVENTUALLY SNOW SHOWERS WITH SLIGHTLY COOLER BUT SEASONABLE TEMPERATURES. && .HYDROLOGY...RELATIVELY QUIET PATTERN CONTINUES. VERY LIGHT QPF WITH SHOWER THREAT THURSDAY AND THURSDAY NIGHT. PRECIP OVER WEEKEND NOT ESPECIALLY GREAT SO NO FLOOD PROBLEMS FOR THE NEXT WEEK ANTICIPATED AT THIS TIME. .AVIATION...A LOT OF UPSTREAM STRATOCU WILL MOVE INTO THE AREA TODAY. LESS CLOUDS ACROSS SOUTHEAST PORTION CWA. CEILINGS GENERALLY VFR WITH BASES 040-060...LCL MVFR CEILINGS MAINLY WEST AND NORTH PORTION. LIGHT AND VARIABLE WINDS THROUGH 12Z THURSDAY. && $$ SHORT TERM (UPDATE)...WASULA PREVIOUS AFD...FISHER/KDL ny AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE WILMINGTON NC 900 PM EST WED NOV 17 2004 .SHORT TERM (REST OF TONIGHT)... SATELLITE PICS AND RUC RH FIELDS AGREE ON KEEPING CLOUDS OUT OF THE AREA OVERNIGHT. WILL UPDATE ZONES TO CHANGE WORDING TO MOSTLY CLEAR. WITH THIS IN MIND...WILL ALSO BUMP DOWN OVERNIGHT LOWS ONE CATEGORY ACROSS THE BOARD. && .AVIATION... HIGH PRESSURE WILL CONTINUE TO HANG ON THROUGH THURSDAY. MID LEVEL RIDGE WILL FLATTEN...ALLOWING A POSSIBLE MID CLOUD CEILING BY TOMORROW AFTERNOON. WINDS WILL BE LIGHT AND VARIABLE THROUGH THE PERIOD. SOME LIGHT FOG POSSIBLE AT THE FLO TERMINAL AROUND SUNRISE...ESPECIALLY IF THE AREA REMAINS CLOUD FREE. && .MARINE... VERY POTENT 5H S/W TROF TO DIVE SE...TO A POSITION AROUND HAT BY 12Z THU. NO BAROCLINIC ZONE AROUND (UN)FORTUNATELY AND LATE FALL SEASON WITH A RELATIVELY STABLE ATMOSPHERE. UPPER AND SFC RIDGING TO PREDOMINATE OVERNITE. LIGHT N TO NE WIND 10 KT OR LESS TO PREVAIL WITH CONTINUED 2-3 FT LONG PERIOD SWELL. WILL KEEP A 2 TO 3 FT SWELL THRU THU WITH WW3 AT TIMES DIMINISHING LONG PERIOD SWELLS TOO QUICKLY. WILL STAY CLOSER TO PREVIOUS FCST WITH SEAS WEST OF FRYING PAN SHOALS DUE TO THE E TO NE SWELL DIRECTION BEING ABSORBED. && .ILM WATCHES/WARNINGS/ADVISORIES... NC...NONE. SC...NONE. MARINE...NONE. && $$ SHORT TERM (UPDATE)...KEEBLER AVIATION (UPDATE)...DOUGLASCARLHOEHLER MARINE (UPDATE)...LOWENTHAL nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 943 AM EST WED NOV 17 2004 .SHORT TERM (REST OF TODAY)... BROUGHT TEMPS UP CWA-WIDE BUT ONLY BY A DEGREE OR TWO..CLOSER TO BUT STILL BELOW MAV...AGAIN BY A DEGREE OR TWO. SKY COVER WILL BE UPDATED TO MOSTLY SUNNY BASED UPON VISIBLE SAT. && .AVIATION... IFR VISIBILITIES IN FOG HAVE IMPROVED TO VFR AT 12Z, BUT THE POTENTIAL EXISTS FOR VISIBILITIES TO DROP TO TEMPO MVFR AROUND SUNRISE, ESPECIALLY AT FLO AND CRE. HIGH PRESSURE TO DOMINATE THROUGH 18/12Z WITH LIGHT NORTH TO NORTHEAST WINDS AND FEW TO SCATTERED CLOUDS AROUND 8K AND SCATTERED CIRRUS. MVFR VISIBILITIES POSSIBLE AGAIN AFTER 18/10Z, ESPECIALLY AT CRE AND FLO. && .MARINE... AS HIGH PRESSURE CONTINUES OVER THE WATERS THIS MORNING A 10 KT NORTHERLY WIND IS SEEN OVER THE WATERS WITH ONLY 3 FT SEAS IN A EAST SWELL. RUC SHOWING WINDS AT 10 TO 15 KT THROUGH THE DAY. SO NO MAJOR CHANGES ARE PLANNED FOR MORNING FORECAST. && .PREVIOUS DISCUSSION... SHORT TERM (TODAY THROUGH THURSDAY)... A TEMPERATURE FORECAST THROUGH THIS PERIOD. CLOUD-COVER FROM A H500 SHORTWAVE PLAYED HAVOC WITH GUIDANCE HIGH TEMPERATURE VALUES TUESDAY. DO EXPECT MORE DIRECT INSOLATION TODAY...ALTHOUGH WILL STILL UNDERCUT GUIDANCE VALUES SLIGHTLY AS WARM AIR ADVECTION CLOUDS MAY ENTER THE CWA...ESPECIALLY THE NORTHERN AND WESTERN AREAS. THREE FEATURES TO PROVIDE INCREASED CLOUD-COVER FOR THURSDAY... ANOTHER H500 SHORTWAVE TRAVERSING THE SOUTHEASTERN RIDGE... ALONG WITH PREFRONTAL TROUGH AHEAD OF A COLD FRONT MOVING TROUGH THE MIDWEST. THERMAL PROFILES AND GUIDANCE VALUES CONTINUE TO INDICATE A WARMING TREND. WILL CONTINUE TO UNDERCUT GUIDANCE SLIGHTLY CONSIDERING IT MAY BE A MOSTLY CLOUDY DAY. LONG TERM (FRIDAY NIGHT THROUGH TUESDAY)... 500MB TROUGH DIGS IN THE WESTERN US AS FLOW OVER SE BECOMES SOUTHWESTERLY. COLD FRONT MOVES SLOWLY TOWARD AND THROUGH THE AREA THROUGH THE PERIOD. WILL NOT TRY TO PINPOINT TIMING AND INTENSITY OF NUMEROUS WAVES MOVING ALONG THIS FRONT...THEREFOR WILL MAINTAIN POPS THROUGH THE ENTIRE DURATION. && .ILM WATCHES/WARNINGS/ADVISORIES... NC...NONE. SC...NONE. MARINE...NONE. && $$ SHORT TERM...MBB AVIATION...MRR MARINE...HAWKINS nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 830 PM CST WED NOV 17 2004 .DISCUSSION...MAIN CHALLENGE THIS EVENING WILL BE WHAT TO DO WITH THE FOG. PRESSURE GRADIENT REMAINS WEAK ALONG AND EAST OF THE VALLEY. THIS COMBINED WITH GOOD LOW LEVEL MOISTURE (DEW POINTS MID TO UPPER 30S) HAS KEPT FOG LINGERING. VISIBILITY EAST OF THE VALLEY HAS DROPPED TO 1/4SM AT MULTIPLE SITES. DO NOT SEE ANYTHING WHICH WILL IMPROVE VISIBILITY UNTIL AFTER MIDNIGHT. WILL ISSUE DENSE FOG ADVISORY FOR A PORTION OF WEST CENTRAL AND NORTHWEST MINNESOTA THROUGH THE EARLY MORNING HOURS. FOLLOWING 00Z RUC...PRESSURE GRADIENT INCREASES AFTER MIDNIGHT WITH WINDS SWITCHING WESTERLY AND INCREASING SOME. IN ADDITION...DRIER AIR MASS FORECASTED TO ADVECT INTO REGION. THIS SHOULD KEEP VISIBILITY UP ALONG THE VALLEY...AND IMPROVE VISIBILITY TOWARD MORNING EAST OF THE VALLEY. CURRENT FORECASTED TEMPERATURES LOOK FINE. UPDATED GRIDS/TEXT TO BE ISSUED BY 845PM. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...DENSE FOG ADVISORY UNTIL 4AM THURSDAY FOR MUCH OF NORTHWEST AND WEST CENTRAL MINNESOTA. && $$ TG nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 335 AM EST THU NOV 18 2004 .SHORT TERM... DENSE FOG ADVISORY WILL BE ISSUED FOR THE ENTIRE CWA UNTIL 14Z (9AM). MONITORING SURFACE OBSERVATIONS CLOSELY THIS MORNING WITH RESPECT TO DENSE FOG. ENHANCED 3.9U IMAGERY SUGGESTS BEHIND THIS STRIP OF STRATUS EXTENDING FROM THE TRI-CITIES TO METRO DETROIT THE VISIBILITIES QUICKLY DROP TO 1/4MI AND VISBILITIES RISING WITH UPSTREAM AREA OF MORE STRATUS. SURFACE COOL FRONT LINED UP FROM NEAR THE STRAIGHTS TO JUST EAST OF THE DOOR PENINSULA AND THEN DRAPING SOUTHWEST ACROSS SOUTHERN WISCONSIN AND THE I-80 CORRIDOR OF IOWA. THIS FRONT IS MOVING A LITTLE SLOWER THAN OPERATIONAL NCEP RUNS WOULD SUGGEST WITH THE NEW RUC MORE IN LINE WITH REALITY. THIS WILL PROLONG THE LOW CLOUDS/FOG/DRIZZLE AND THE CHANCE FOR A LITTLE OF LIGHT RAIN ACROSS THE SOUTHERN COUNTIES. UPSTREAM RADAR COMPOSITES SHOW AN AREA OF LIGHT RAIN SHOWERS FROM NORTHERN IOWA/SOUTHERN MINNESOTA INTO PORTIONS OF WISCONSIN. HOWEVER PRECIP IS HAVING A TOUGH TIME REACHING THE GROUND ON THE EASTERN EDGE AS 00Z RAOB FROM GRB SHOWS QUITE BIT OF DRY AIR BETWEEN 850-650MBS. UPSTREAM VIS/CLOUD OBSERVATIONS REVEAL CLOUD DECKS NEAR 9000 FEET WITH JUST SOME REPORTING STATIONS SHOWING SOME LIGHT RAIN. TRENDS IN THE RECENT RUC SUGGEST THIS IS ALONG A 850-700MB THETA-E GRADIENT THAT MOVES SOUTH OF M59 THIS MORNING. THEREFORE, WE WILL ADD IN THE CHANCE FOR SOME LIGHT RAIN FOR THE SOUTHERN FOUR COUNTIES. && .DISCUSSION... WATER VAPOR LOOP THIS MORNING IS QUITE ACTIVE WITH 5 DISTINCT SHORT WAVES (DEPARTING WAVE NOW MOVING EAST OF THE MID-ATLANTIC, OUR LONG LIVED WAVE FROM BAJA CALIFORNIA NOW MOVING ACROSS OKLAHOMA, NEXT WAVE QUICKLY TRACKING EAST FROM LAKE WINNIPEG TOWARD JAMES BAY, AND THE LAST ONE ENTERING THE PACIFIC NORTHWEST COAST. THIS CORRESPONDS TO A RELATIVELY DISORGANIZED UPPER JET FLOW ACROSS NOAM AS JET STREAK FEATURES ARE DIFFICULT TO ASCERTAIN. OUR MAIN PLAYER IS CURRENTLY SITUATED ACROSS OKLAHOMA AND WILL IMPACT OUR REGION IN THE FORM OF RAIN ON FRIDAY. UPSTREAM COOL FRONT IS SCHEDULED TO SLIP SOUTH OF THE STATE LINE DURING THE AFTERNOON HOURS. SURFACE DEWPOINTS BEHIND THIS FRONT DROP BACK TO THE MIDDLE 40S WITH MIDDLE 30S FURTHER BACK INTO WISCONSIN. BUT WILL WE OBSERVE THESE LOWER VALUES ACROSS OUR STATE REMAINS TO BE SEEN. THE AFOREMENTIONED WAVE RACING EAST ACROSS CANADA WILL BE THE KEY PLAYER. THIS WAVE APPEARS TO BE BETTER HANDLED IN THE ETA THIS MORNING WHICH SUGGESTS HEIGHT RISES ACROSS LAKE WINNIPEG AND THE DAKOTAS WILL CONTINUE AND HELP STRENGTHEN THE SURFACE HIGH. WITH THAT SAID, OUR MID LEVEL HEIGHT FIELD BECOMES NEARLY ZONAL WHICH MIGHT STALL THIS FRONT NEAR OR JUST NORTH OF THE STATE LINE THIS AFTERNOON. THERE IS PLENTY OF MOISTURE UPSTREAM AND WITH COMBINATION OF SOUTHERN PLAINS WAVE LIFTING NORTH, WE MIGHT HAVE TO MONITOR THE CHANCES FOR MORE RAIN ACROSS THOSE SOUTHERN COUNTIES. FOR NOW, WE WILL ONLY HAVE MENTION DURING THE MORNING AS DAY CREW WILL MONITOR SHORT TERM TRENDS AND MAKE ADJUSTMENTS IF NEED BE. TEMPS WILL ALSO BE TRICKY AS PLENTY OF CLOUDS AND LOCATION OF THIS FRONT WILL DICTATE WHERE WE WILL OBSERVE 60F. WE WILL BANK ON NEAR 60 SOUTH 1/2 AND UPPER 50S NORTH 1/2. CROSS SECTIONS OVERNIGHT SHOW AN INCREASING EAST WIND AS SURFACE HIGH FROM THE PLAINS STRENGTHENS ACROSS LAKE SUPERIOR WITH PLENTY OF DRY AIR ASSOCIATED WITH IT AND FILTERING SOUTH. MEANWHILE, OUR SOUTHERN SYSTEM BEGINS TO LIFT FURTHER NORTH AND INCREASING IN FORWARD SPEED. PLENTY OF MID-HIGH LEVEL MOISTURE TO KEEP SKIES IN THE MOSTLY CLOUDY TO CLOUDY RANGE (500MB AND UP) WITH LOWER CLOUD DECK FILTERING IN THROUGHOUT THE NIGHT. AGEOSTROPHIC FLOW IN THE 850-700 LAYER INCREASES TO BETWEEN 10-15 KNOTS FROM THE NORTHEAST WHICH WILL NOT ONLY ENHANCE THE DRIER AIR ADVECTING INTO THE REGION BUT INCREASE THE THETA-E GRADIENT UPSTREAM AND FGEN FIELDS. BY FRIDAY MORNING (JUST BEFORE SUNRISE)...WOULD EXPECT RAIN CHANCES INCREASING ACROSS THE FAR SOUTH AND WILL CONTINUE WITH THE CHANCE OF RAIN THERE. FURTHER NORTH, CLOUDS WILL PERSIST AND WITH SOME OF THIS DRIER AIR AT THE SURFACE WE SHOULD BE ABLE TO DROP TEMPS BACK INTO THE LOWER HALF OF THE 40S...PERHAPS SOME UPPER 30S FOR PORTIONS OF BAY-MIDLAND COUNTIES IF DRIER AIR IS DEEP ENOUGH. STRONG ISENTROPIC ASCENT WILL EVENTUALLY OVERCOME THE DRIER LOWER LEVELS AND WITH PRECIPITABLE WATERS CLIMBING TOWARD 1" (WHICH IS OVER 200% OF NORMAL)...RAIN WILL SPREAD FROM SOUTH TO NORTH THROUGHOUT THE DAY FRIDAY. IT MAY TAKE ALL DAY FOR THE NORTHERN 1/3RD OF THE CWA AND WE WILL HOLD ONTO THE HIGH CHANCE THERE. WEAK SURFACE LOW ASSOCIATED WITH THE UPPER SYSTEM (1010MB) WILL TRACK ACROSS THE WESTERN LAKES WITH OCCLUDED FRONT HEADING NORTH ACROSS THE STATE FRIDAY NIGHT. IMPRESSIVE DEEP THETA-E RIDGE OVERHEAD WILL RESULT IN OCCASIONAL LIGHT RAIN/DRIZZLE/FOG AND TEMPERATURES EITHER HOLDING STEADY OR SLOWLY RISING OVERNIGHT. STILL RETAIN THE CHANCE FOR SHOWERS ON SATURDAY BUT MODEL MOISTURE FIELDS ARE TRENDING TOWARD DRIER CONDITIONS (IE NOT NEARLY AS DEEP IN THE MOISTURE PROFILES)...BUT STILL PLENTY OF CLOUDS AROUND. WE ARE STILL ON TAP FOR A RETURN TO COOLER WEATHER ALONG WITH RAIN AND SNOW SHOWERS. TIMING OF INDIVIDUAL WAVES IS ALWAYS PROBLEMATIC AND LAKE CONTRIBUTION INFLUENCES. BUT WOULD EXPECT ALL OF THE REGION TO SEE SOME SNOW FALLING THE WEEK OF THANKSGIVING. && .DTX WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY IN EFFECT...UNTIL 14Z...ENTIRE CWA. && $$ BGM EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 253 AM EST THU NOV 18 2004 .DISCUSSION... SHORT TERM CONCERNS REVOLVE AROUND FOG AND CLOUD COVER...THEN ATTENTION TURNS TOWARD CHANCES FOR PCPN FRIDAY NIGHT AND BEYOND. LATEST WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSES CONTINUE TO SHOW SPLIT FLOW OVER NORTH AMERICA...WITH SHORTWAVES QUICKLY MOVING THROUGH ZONAL FLOW JUST NORTH OF THE US/CANADA BORDER AND MORE SLOWLY MOVING SHORTWAVES IN THE SOUTHERN STREAM OVER THE SOUTHERN US. THE GENERAL THEME AS WE HEAD INTO THE WEEKEND WILL BE FOR THE VIGOROUS SHORTWAVE CURRENTLY OFF THE BRITISH COLUMBIA COAST TO DIG A TROUGH OVER THE CENTRAL US...HELPING TO DEVELOP A SURFACE LOW OVER THE MID-MISSISSIPPI VALLEY WHICH WILL MOVE NORTHEAST ACROSS THE WESTERN GREAT LAKES SATURDAY-SUNDAY. THE ETA AND GFS ARE IN FAIRLY GOOD AGREEMENT ON THE LARGE SCALE FEATURES THROUGH THE PERIOD...WITH SOME MINOR DIFFERENCES IN TIMING AND POSITION WITH THE SURFACE LOW OVER THE WEEKEND. WILL FAVOR THE ETA IN THE SHORTER TERM...PARTICULARLY WITH THE HANDLING OF LOW CLOUDS/MOISTURE TODAY THROUGH TONIGHT...BUT WILL THEN TREND TOWARD THE GFS WHICH IS A BIT FASTER IN MOVING THE SURFACE LOW AND ASSOCIATED FRONT EAST OF THE AREA LATE SATURDAY-SUNDAY. PREFER THE SLIGHTLY MORE ZONAL UPPER FLOW OVER THE GREAT LAKES REGION IN THE GFS BY SUNDAY...RESULTING FROM ITS CUTTING OFF OF ENERGY FARTHER WEST IN THE SOUTHWESTERN US. IN THE VERY NEAR TERM...WILL HAVE TO DEAL WITH PESKY FOG AND LOW CLOUDS FOR AT LEAST PART OF THE MORNING. LATEST 11-3.9 MICRON IMAGERY SHOWS BREAKS IN THE LOW CLOUDS AND FOG OVER THE WESTERN AND CENTRAL CWFA...WITH SOME CIRRUS AND AC STREAMING INTO THE REGION. THE LOW CLOUDS AND FOG APPEAR TO BE BREAKING UP IN CONJUNCTION WITH DRIER SFC-850MB AIR WHICH IS MOVING INTO THE AREA PER THE 00Z ETA. A LOOK AT 00Z SOUNDINGS FROM INTERNATIONAL FALLS AND PICKLE LAKE SHOWS WARMER TEMPERATURES WERE PRESENT AT PICKLE LAKE AROUND 925MB...WITH LOWER DEWPOINTS AND SIGNIFICANTLY LOWER RH VALUES. THE ETA BRINGS THIS SUBTLE THERMAL RIDGE INTO THE AREA THIS MORNING...WHICH WILL WORK TO SCOUR OUT THE LOW CLOUDS/FOG FROM WEST TO EAST. SINCE THIS TREND IS ALREADY STARTING TO OCCUR...HAVE REASONABLE CONFIDENCE IT WILL CONTINUE THROUGH THE MORNING HOURS. THE PRESENCE OF AC/CIRRUS SHOULD KEEP AREAS WHICH LOSE THEIR LOW CLOUDS FROM RADIATING AND FOGGING BACK IN...PARTICULARLY WITH LOWER DEWPOINTS BEGINNING TO WORK IN. SO...WILL TRIM BACK THE DENSE FOG ADVISORY A BIT...AND WILL LIKELY ONLY MAINTAIN IT OVER THE SOUTHEAST AND EASTERN CWFA THROUGH PART OF THE MORNING. OTHERWISE...WILL ALLOW FOR GENERAL CLEARING FROM WEST TO EAST THROUGH THE DAY. TONIGHT...THE ETA AND GFS BUILD THE LOW LEVEL RIDGE OVER THE CWFA...BUT ALSO MANAGE TO BRING A 925MB THERMAL TROUGH SOUTH INTO THE AREA ON NORTHEAST FLOW. AM SOMEWHAT CONCERNED THAT THIS COULD LEAD TO QUITE A BIT OF LOW CLOUD DEVELOPMENT OVERNIGHT TONIGHT...PARTICULARLY OVER THE NORTHEAST CWFA AND IN UPSLOPE AREAS. WILL ALLOW FOR SOME INCREASE IN CLOUD COVER TONIGHT...BUT WILL NOT GET TOO CARRIED AWAY AT THIS POINT. HOWEVER...IT SHOULD BE NOTED THAT AN AREA OF LOW CLOUDS COINCIDENT WITH THIS THERMAL TROUGH CAN CURRENTLY BE SEEN OVER NORTHERN MANITOBA...SO WILL AT LEAST TREND TOWARD INCLUDING MORE CLOUD COVER OVER THE NORTH. ANY LOW CLOUDS OVER THE AREA FRIDAY MORNING SHOULD BREAK UP DURING THE DAY...PARTICULARLY BY AFTERNOON AS RETURN FLOW BEGINS TO SETUP. SHORTWAVE ENERGY WILL LIFT NORTHEAST FROM THE CENTRAL PLAINS FRIDAY NIGHT THROUGH SATURDAY...HELPING TO DEVELOP A SURFACE LOW OVER THE MISSISSIPPI VALLEY. THIS LOW WILL LIFT NORTHEAST AND LIKELY PASS ACROSS LAKE MICHIGAN BY LATE SATURDAY AFTERNOON. THE BULK OF FORCING ASSOCIATED WITH THIS FEATURE WILL BE PROVIDED BY WAA/ISENTROPIC LIFT...WHICH IS SEEN NICELY ON THE 295-300K ISENTROPIC SURFACES. AS IS OFTEN THE CASE WITH WARM ADVECTION PCPN EVENTS...THE LATEST MODEL RUNS ARE A BIT SLOWER TO BRING THE PCPN INTO THE AREA...WHICH MAKES SENSE GIVEN THE VERY DRY AIR WHICH SHOULD BE IN PLACE. LATEST PROGS SUGGEST PCPN WILL MOVE IN FROM SOUTHWEST TO NORTHEAST...GETTING INTO THE WISCONSIN BORDER COUNTIES FRIDAY EVENING...THEN SPREADING NORTHEAST ACROSS THE REMAINDER OF THE CWFA BY SATURDAY MORNING. WILL CONTINUE TO CARRY LIKELY POPS...WHICH WILL PROBABLY BE ABLE TO BE BUMPED UP TO CATEGORICAL VALUES ONCE THE TIMING BECOMES MORE CERTAIN. THE MID-LEVELS DRY OUT AND LARGE SCALE FORCING DEPARTS SATURDAY NIGHT AS COOLER BOUNDARY LAYER AIR MOVES INTO THE AREA. THERE MAY BE A SHORT WINDOW FOR A CHANGEOVER OF THE SYNOPTIC SCALE PCPN FROM RAIN TO SNOW...BUT AM NOT TOO CONCERNED ABOUT THIS POSSIBILITY. THE MAIN CHANCE FOR ANY SNOW WILL BE WITH INSTABILITY/LAKE EFFECT SNOW SHOWERS WHICH COULD DEVELOP LATER ON SUNDAY INTO EARLY NEXT WEEK AS COLDER 925-850MB TEMPERATURES MOVE INTO THE AREA. WILL MAINTAIN THE GOING FORECAST IN THIS REGARD SINCE THE 00Z OPERATIONAL RUNS STILL LOOK FAIRLY SIMILAR TO PREVIOUS RUNS. LATER SHIFTS CAN EVALUATE ADDITIONAL GUIDANCE AND ENSEMBLE PROGS AND MAKE MODIFICATIONS TO THE FORECAST FOR EARLY NEXT WEEK IF NEEDED. && .MQT WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY THROUGH 9 AM EST (8 AM CST) MIZ006-007-013-014-085. && $$ TRH mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 1102 AM EST THU NOV 18 2004 UPDATED FIRE WEATHER AND WWA SECTION FOR RED FLAG WARNING. .DISCUSSION...THE UPPER LOW IS MOVING ENE ACROSS OK THIS MORNING. THE DOWNSTREAM RIDGE AXIS IS NOW OVERHEAD LOCALLY AND EXTENDS NWD INTO LOWER MI. CIRRUS CLOUDS ARE SPILLING OVER THE RIDGE INTO THE CWFA. SURFACE HIGH PRESSURE REMAINS CENTERED OVER THE SE CONUS. THE 12Z KTLH SOUNDING SHOWS THAT VERY DRY AIR REMAINS IN PLACE OVER THE AREA WITH THE PW JUST 0.41 INCHES. SEE FIRE WEATHER DISCUSSION BELOW. NO PUBLIC FORECAST UPDATE IS PLANNED TODAY. && .MARINE...WINDS OVER THE COASTAL WATERS ARE E AT 10-15 KT THIS MORNING. SEAS AT THE BUOYS HAVE BEEN RUNNING 3-4 FT. THIS IS ALL REFLECTED IN THE CURRENT FORECAST, SO NO CHANGES WILL BE NECESSARY. WINDS & SEAS ARE FORECAST TO REMAIN BELOW CAUTION THROUGH MON. WINDS WILL VEER TO A MORE SLY COMPONENT BY FRI NIGHT AND THIS SHOULD THEN PERSIST THROUGH THE REMAINDER OF THE PERIOD. && .FIRE WEATHER...YESTERDAY'S MIXED LAYER REMAINS EVIDENT ABOVE THE SURFACE INVERSION IN THIS MORNING'S KTLH SOUNDING. WE ARE CONCERNED THAT THE DEW POINT WILL ONCE AGAIN MIX OUT LOWER THAN INDICATED BY MOS, AS HAPPENED YESTERDAY. THE LATEST RUC40 SHOWS RED FLAG CRITERIA DEVELOPING. A MITIGATING FACTOR IS THAT THE LOW LEVEL FLOW HAS MORE OF AN ELY COMPONENT THAN YESTERDAY, AND MOISTURE LEVELS HAVE INCREASED SUBSTANTIALLY BELOW 800 MB. WE SHOULD NOT SEE ANOTHER 7 HOUR EVENT, BUT 5 TO 6 HOUR DURATIONS WILL BE POSSIBLE ACROSS OUR INLAND FL ZONES. THEREFORE, A RED FLAG WARNING HAS BEEN ISSUED. && .PREV DISCUSSION... 200 AM EST THU NOV 18 2004 SHORT TERM...TODAY THROUGH FRIDAY NIGHT. HIT RED FLAG WARNING CONDITIONS YESTERDAY...AS QUITE A BIT OF DRY AIR MIXED OUT. TODAY LOOKING TO BE A MARGINAL EVENT OVER INLAND LOCALES OF N FL...SO WILL GO WITH STATEMENT OF 1-3 HOURS POSSIBLE INLAND THIS AFTERNOON. OTHERWISE...TODAY HIGH PRESSURE AT THE SURFACE WITH ONLY CIRRUS EXPECTED. WINDS A BIT MORE EAST AS SURFACE HIGH DRIFTS A BIT MORE EAST. WARMER TEMPS TO THE REACH THE LOWER & SOME MID 70S. TONIGHT...PARTLY CLOUDY & MILDER WITH LIGHT SE FLOW BY MORNING. LOW CHANCE OF SHOWERS FL PANHANDLE FRIDAY MORNING TO AFTERNOON...MOST OTHERS SLIGHT TO NIL. FRIDAY NIGHT THE CHANCES OF RAIN REMAIN LOW TO SLIGHT...AS THE SURFACE HIGH CONTINUES TO WEAKEN & THE UPPER SYSTEM IN THE PLAINS MAKES SOME PROGRESS EAST. LONG TERM...SATURDAY THROUGH WEDNESDAY. MODELS SIMILAR WITH SLOWING DOWN APPROACHING SYSTEM AS THE SURFACE HIGH HOLDS OFF THE EAST COAST...AS WELL AS THE THE UPPER RIDGE. POP FORECASTS WILL REMAIN IN CHANCE CAT MUCH OF PERIOD UNTIL THE SYSTEM MAKES MORE PROGRESS EAST. A BOUNDARY SETTLES NEAR CWA ON MONDAY...BUT THEN LIFTS BACK NORTH ON TUESDAY THROUGH WEDNESDAY. THEN A COLD FRONT IS SEEN IN THE GFS FOR THURSDAY. SURFACE HIGH BUILDS IN FOR FRIDAY. TEMPS WILL GENERALLY BE A BIT COOLER THAN NORMAL FOR HIGHS...WHILE LOWS A BIT WARMER. && .PRELIMINARY POINT TEMPS/POPS... TLH 74 48 75 57/ 00 10 20 20 PFN 74 56 75 62/ 00 20 30 30 DHN 72 54 72 58/ 00 20 30 30 ABY 73 49 74 56/ 00 10 20 20 VLD 74 49 76 56/ 00 10 10 10 CTY 75 49 77 58/ 00 10 10 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...RED FLAG WARNING 11 AM UNTIL SUNSET FOR FLZ11-13-16>19-26-27. && $$ CURRENT...WOOL/18 PREVIOUS...MCT fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 651 AM EST THU NOV 18 2004 .AVIATION... EXACERBATING SITU THIS AM WRT TO TAFS. MODEL GUIDANCE AS A WHOLE MUCH TOO PESSIMISTIC GIVEN UPSTREAM TRENDS ACRS IL INTO WRN IN. INCOMING MID/HIGH CLD SHIELD RAPIDLY OVERSPREADING THE AREA HELPING MATTERS AS IS RENEWED BUT SCT SHRA. OF IMMEDIATE CONCERN IS AREA OF LIFR WHICH HAD DEVELOPED UPSTREAM IN WI ALG WK SFC TROUGH. MORE OF AN ISSUE FOR SBN AS BNDRY PIVOTS SWD IN RESPONSE TO BACKING LL FLW AHD OF STG SRN STREAM LOW HEADED FOR THE AREA TONIGHT. FWA SHLD STAY S BUT POSES MORE OF A CHALLENGE GIVEN LG STRATUS WEDGE OVR OH LIKELY NOT BREAKING UP THIS AFTN AND POTENTIAL TO ADVT WWD INTO FWA AREA LTR TDA. DAY SHIFT WILL NEED TO MONITOR THAT OTHERWISE FOLLOWING MORE OPTIMISTIC RH TRENDS SEEN IN SHRT TERM RUCII DATA AND OBSERVATIONS. && .SHORT TERM... IMPRESSIVE SRN STREAM SYS POISED TO OPEN AND EJECT NE AHD OF POWERHOUSE NRN STREAM WV COMING INTO BC THIS AM. FLOOD GATE OF MSTR IN PLACE DOWNSTREAM W/00Z H2O PLOT TELLING THE TALE AS MANY RAOBS AOA 200% OF NORMAL. MSTR PLUME NOT GOING ANYWHERE TOO SOON AND GIVEN CONTD PROXIMITY OF LL THETA GRADIENT AND WK UPR WV ALG SRN EDGE OF WESTERLIES UPSTREAM OVR WI...HAVE ADDED MORE POPS THIS AFTN S OF IN/MI BORDER. ALREADY COMPOSITE RADARS SHOWING QUITE A FEW SHOWERS OVR CNTRL/SRN WI AND INTO NRN IL AND MAY HAVE TO BACK THINGS UP FURTHER IN GRIDS BEFORE ALL IS SAID AND DONE ON THIS FTR FOR TDA. OTHERWISE OTHER PROBLEM THAT BEARS WATCHING IS FOG WHICH HAS BECOME DENSE ACRS NE IN CONJUCTION W/LOSS OF MID LVL CLD DECK...ALTHOUGH THAT APPEARS TO BE SHRT LIVED GIVEN ADDNL MID CLDS STREAMING EWD AHD OF WK WV IN WI AND MIGHT SQUEEK BYE WITHOUT HAVING TO POST AN ADVISORY. LTL CHC FOR INSOLATIVE INPUT THIS AFTN AND VRY LIMITED MIXING AGAIN SUGGEST CUTTING TEMPS BACK SOME FOR THIS AFTN ALTHOUGH PASSAGE OF WI UPR TROUGH AND BACKING LL WINDS IN RESPONSE TO EJECTING SRN WV LOOK TO PULL DOWN A BIT DRIER AIR LOCATED UP N BUT SRN EXTENT BEFORE STALLING TONIGHT HIGHLY QUESTIONABLE. HAVE MY DOUBTS IT WILL MAKE IT MUCH BEYOND THE BORDER AND HAVE REFINED OVERNIGHT MINS TO CORRELATE. PRESENCE OF LL THETA GRADIENT AND INCREASING UPR SPRT IN TANDEM W/DEEP MSTR PLUME IN PLACE SPELL CAT TO LIKELY POPS THEN TOO EXCEPT FAR NE BY DAYBREAK FRI. && .LONG TERM... FRIDAY THROUGH WEDNESDAY. MODELS STILL FOCUSING MUCH OF THE PRECIP ACROSS THE FORECAST AREA MAINLY FRI AM...WITH THE BULK OF THE LIFT SHIFTING NORTHEAST DURING THE AFTERNOON. HAVE OPTED TO GO CAT POPS ALL DAY...BUT LOW END OF CAT POPS IN SW COUNTIES IN AFTERNOON TO SHOW SOMEWHAT OF A DECREASING TREND. WITH EXPECTED CLOUD CVR AND PRECIP...NOT EXPECTING MUCH OF A RISE IN TEMPS...WITH READINGS IN THE MID 50S LOOKING GOOD...ON TRACK WITH GUIDANCE. FRIDAY NIGHT REMAINS A CHALLENGE AS BEST LIFT WILL BE NORTH OF THE AREA BUT WITH SFC LOW STILL TO OUR IMMEDIATE WEST AND DEEP MSTR STILL IN PLACE...DON'T THINK IT WILL TAKE MUCH TO GET SOME SHOWERS OR AREAS OF RAIN...SO HAVE KEPT LIKELY POPS. THROUGH SATURDAY EVENING...CHC POPS STILL WARRANTED AS LOW BEGINS TO MOVE NORTHEAST ACROSS MICHIGAN AND UPPER LEVEL TROUGH MOVES CLOSER TO THE AREA. 850 MB TEMPS WILL RISE A FEW DEGREES...WHICH WITH SOME BREAKS IN THE CLOUDS EXPECTED...TEMPS SHOULD MAKE IT INTO THE MID-UPR 50S AND POSSIBLY INTO THE 60S. STAYING ON COOLER END OF GUIDANCE FOR NOW DUE TO UNCERTANTITY. PRECIP SHOULD BE CLEAR OF THE AREA BY LATER SATURDAY NIGHT. DRY CONDITIONS WILL PREVAIL WITH MORE SEASONABLE TEMPERATURES EXPECTED ACROSS MUCH OF THE AREA THROUGH WEDNESDAY AS RIDGE TAKES HOLD OVER THE AREA. LATER FORECASTS WILL NEED TO ADDRESS LAKE EFFECT POTENTIAL LATE IN THE WEEKEND AS FAVORABLE DELTA T'S WILL OCCUR...BUT FETCH NOT THE BEST FOR LAKE EFFECT PRECIP OVER THE FAVORED COUNTIES. SOME CONCERNS NOW STARTING TO EVOLVE ON POTENTIAL FOR FIRST SNOWFALL OF THE SEASON IF ECMWF/GEM (AND GFS TO LESSER DEGREE) COME TRUE WITH STRENGTHENING LOW MOVING OUT OF THE GULF STATES...TRACKING OVER CENTRAL OHIO ON WEDS WITH 1000-850 MB THICKNESSES AOB 1530. TOO EARLY TO DEAL WITH IN GRIDS SO STATUS QUO FOR NOW. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. && AVIATION/SHORT TERM...HOLSTEN LONG TERM...FISHER $$ in AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 920 AM EST THU NOV 18 2004 .UPDATE... VISIBLE SATELLITE IMAGE SHOWS NUMEROUS BREAKS DEVELOPING IN CLOUD FIELD OVER THE WESTERN AND CENTRAL GREAT LAKES...ESPECIALLY OVER THE NORTHERN PORTION OF THE CWA WHERE SURFACE WINDS ARE BECOMING NORTHWEST IN THE WAKE OF COLD FRONT. ETA20 AND RUC BOTH INDICATE GOOD DRYING BELOW 1000 FT IN WAKE OF COLD FRONT AS WELL AND SURFACE OBS AND SATELLITE SUPPORTING THIS. AS A RESULT FOG AND LOW CLOUD DISSIPATING RAPIDLY...DENSE FOG ADVISORY CANCELLED AT 845 AM AS WELL. ANTICIPATE WIDESPREAD 3-5 MILE VSBYS BY 11 AM. WILL ALSO REMOVE MENTION OF PRECIP AS DRIZZLE HAS DIMINISHED AS LOW CLOUDS LIFT. LIGHT RAIN OVER NORTHERN LOWER SHOULD NOT DRIFT TO MUCH FURTHER SOUTH AS ASSOCIATED UPPER WAVE SHEARS EAST. && GSS .PREV DISCUSSION...ISSUED AT 335 AM WATER VAPOR LOOP THIS MORNING IS QUITE ACTIVE WITH 5 DISTINCT SHORT WAVES (DEPARTING WAVE NOW MOVING EAST OF THE MID-ATLANTIC, OUR LONG LIVED WAVE FROM BAJA CALIFORNIA NOW MOVING ACROSS OKLAHOMA, NEXT WAVE QUICKLY TRACKING EAST FROM LAKE WINNIPEG TOWARD JAMES BAY, AND THE LAST ONE ENTERING THE PACIFIC NORTHWEST COAST. THIS CORRESPONDS TO A RELATIVELY DISORGANIZED UPPER JET FLOW ACROSS NOAM AS JET STREAK FEATURES ARE DIFFICULT TO ASCERTAIN. OUR MAIN PLAYER IS CURRENTLY SITUATED ACROSS OKLAHOMA AND WILL IMPACT OUR REGION IN THE FORM OF RAIN ON FRIDAY. UPSTREAM COOL FRONT IS SCHEDULED TO SLIP SOUTH OF THE STATE LINE DURING THE AFTERNOON HOURS. SURFACE DEWPOINTS BEHIND THIS FRONT DROP BACK TO THE MIDDLE 40S WITH MIDDLE 30S FURTHER BACK INTO WISCONSIN. BUT WILL WE OBSERVE THESE LOWER VALUES ACROSS OUR STATE REMAINS TO BE SEEN. THE AFOREMENTIONED WAVE RACING EAST ACROSS CANADA WILL BE THE KEY PLAYER. THIS WAVE APPEARS TO BE BETTER HANDLED IN THE ETA THIS MORNING WHICH SUGGESTS HEIGHT RISES ACROSS LAKE WINNIPEG AND THE DAKOTAS WILL CONTINUE AND HELP STRENGTHEN THE SURFACE HIGH. WITH THAT SAID, OUR MID LEVEL HEIGHT FIELD BECOMES NEARLY ZONAL WHICH MIGHT STALL THIS FRONT NEAR OR JUST NORTH OF THE STATE LINE THIS AFTERNOON. THERE IS PLENTY OF MOISTURE UPSTREAM AND WITH COMBINATION OF SOUTHERN PLAINS WAVE LIFTING NORTH, WE MIGHT HAVE TO MONITOR THE CHANCES FOR MORE RAIN ACROSS THOSE SOUTHERN COUNTIES. FOR NOW, WE WILL ONLY HAVE MENTION DURING THE MORNING AS DAY CREW WILL MONITOR SHORT TERM TRENDS AND MAKE ADJUSTMENTS IF NEED BE. TEMPS WILL ALSO BE TRICKY AS PLENTY OF CLOUDS AND LOCATION OF THIS FRONT WILL DICTATE WHERE WE WILL OBSERVE 60F. WE WILL BANK ON NEAR 60 SOUTH 1/2 AND UPPER 50S NORTH 1/2. CROSS SECTIONS OVERNIGHT SHOW AN INCREASING EAST WIND AS SURFACE HIGH FROM THE PLAINS STRENGTHENS ACROSS LAKE SUPERIOR WITH PLENTY OF DRY AIR ASSOCIATED WITH IT AND FILTERING SOUTH. MEANWHILE, OUR SOUTHERN SYSTEM BEGINS TO LIFT FURTHER NORTH AND INCREASING IN FORWARD SPEED. PLENTY OF MID-HIGH LEVEL MOISTURE TO KEEP SKIES IN THE MOSTLY CLOUDY TO CLOUDY RANGE (500MB AND UP) WITH LOWER CLOUD DECK FILTERING IN THROUGHOUT THE NIGHT. AGEOSTROPHIC FLOW IN THE 850-700 LAYER INCREASES TO BETWEEN 10-15 KNOTS FROM THE NORTHEAST WHICH WILL NOT ONLY ENHANCE THE DRIER AIR ADVECTING INTO THE REGION BUT INCREASE THE THETA-E GRADIENT UPSTREAM AND FGEN FIELDS. BY FRIDAY MORNING (JUST BEFORE SUNRISE)...WOULD EXPECT RAIN CHANCES INCREASING ACROSS THE FAR SOUTH AND WILL CONTINUE WITH THE CHANCE OF RAIN THERE. FURTHER NORTH, CLOUDS WILL PERSIST AND WITH SOME OF THIS DRIER AIR AT THE SURFACE WE SHOULD BE ABLE TO DROP TEMPS BACK INTO THE LOWER HALF OF THE 40S...PERHAPS SOME UPPER 30S FOR PORTIONS OF BAY-MIDLAND COUNTIES IF DRIER AIR IS DEEP ENOUGH. STRONG ISENTROPIC ASCENT WILL EVENTUALLY OVERCOME THE DRIER LOWER LEVELS AND WITH PRECIPITABLE WATERS CLIMBING TOWARD 1" (WHICH IS OVER 200% OF NORMAL)...RAIN WILL SPREAD FROM SOUTH TO NORTH THROUGHOUT THE DAY FRIDAY. IT MAY TAKE ALL DAY FOR THE NORTHERN 1/3RD OF THE CWA AND WE WILL HOLD ONTO THE HIGH CHANCE THERE. WEAK SURFACE LOW ASSOCIATED WITH THE UPPER SYSTEM (1010MB) WILL TRACK ACROSS THE WESTERN LAKES WITH OCCLUDED FRONT HEADING NORTH ACROSS THE STATE FRIDAY NIGHT. IMPRESSIVE DEEP THETA-E RIDGE OVERHEAD WILL RESULT IN OCCASIONAL LIGHT RAIN/DRIZZLE/FOG AND TEMPERATURES EITHER HOLDING STEADY OR SLOWLY RISING OVERNIGHT. STILL RETAIN THE CHANCE FOR SHOWERS ON SATURDAY BUT MODEL MOISTURE FIELDS ARE TRENDING TOWARD DRIER CONDITIONS (IE NOT NEARLY AS DEEP IN THE MOISTURE PROFILES)...BUT STILL PLENTY OF CLOUDS AROUND. WE ARE STILL ON TAP FOR A RETURN TO COOLER WEATHER ALONG WITH RAIN AND SNOW SHOWERS. TIMING OF INDIVIDUAL WAVES IS ALWAYS PROBLEMATIC AND LAKE CONTRIBUTION INFLUENCES. BUT WOULD EXPECT ALL OF THE REGION TO SEE SOME SNOW FALLING THE WEEK OF THANKSGIVING. && .DTX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ BGM EXPERIMENTAL GRAPHICAL FORECASTS ARE AVAILABLE ONLINE AT HTTP://WWW.CRH.NOAA.GOV/DTX (ALL LOWER CASE) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 930 AM EST THU NOV 18 2004 .SHORT TERM (THIS AFTERNOON)... IN WATER VAPOR THIS MORNING LOW / VORT MAX CENTERED TO THE NORTHEAST OF CWA AND EXPECTED TO PASS OFF TO OUR EAST THIS AFTERNOON. RADAR SHOWING A FEW SPRINKLES APPROACHING NORTHERN AREAS. KCTZ IS REPORTING LIGHT RAIN. WILL ADD ISOLATED LIGHT RAIN TO THE AFTERNOON FORECAST BUT AS LIFT AND CLOUDS QUICKLY MOVE ON IT WILL BE OVER EARLY. && .AVIATION... EXCEPT FOR SOME TEMPO MVFR VISIBILITIES FROM 12-14Z, TERMINALS EXPECTED TO REMAIN VFR THROUGH 19/12Z. A WELL DEFINED VORT MAX IN SOUTHEAST VIRGINIA IS MOVING SOUTHEAST, SPREADING AN EXTENSIVE 6K CLOUD DECK ALONG WITH IT. THIS CLOUD DECK IS EXPECTED TO PERSIST AT FLO THROUGH 19/12Z, WHILE SOME SCATTERING OF THIS CLOUD DECK IS POSSIBLE FOR THE COASTAL TERMINALS AFTER 20Z AS VORT PASSES AND STRONGEST NVA SETTLES IN. WITH THE CLOUD DECK PERSISTING JUST TO THE WEST OF THE COASTAL TERMINALS, SOUTHWEST TO WEST FLOW AT 85H AFTER 19/00Z SHOULD ALLOW CLOUD DECK TO ADVECT BACK EAST INTO THE COASTAL TERMINALS, WHERE IT WILL PERSIST THROUGH 19/12Z. && .MARINE... LIGHT WINDS OVER THE WATERS AND 12Z RUC CONTINUE TO SHOW WINDS LESS THAN 10 KNOTS BUT WITH A SLIGHT VEERING THROUGH THE EVENING. STILL SEEING A 2.5 FT SWELL OVER THE WATERS SO MAY TWEAK SEA UP A 1/2 FOOT FOR THE AFTERNOON. && .ILM WATCHES/WARNINGS/ADVISORIES... NC...NONE. SC...NONE. MARINE...NONE. && $$ SHORT TERM...HAWKINS AVIATION...MR MARINE...HAWKINS nc