AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 840 PM EDT FRI SEP 16 2005 .SYNOPSIS...LATEST WATER VAPOR IMAGES SHOW TROPICAL STORM OPHELIA ACCELERATING TO THE NORTHEAST AS A MID-UPPER TROUGH APPROACHES THE APPALACHIANS. A SURFACE COLD FRONT EXTENDS FROM EASTERN OHIO THROUGH MIDDLE TENNESSEE TO EASTERN TEXAS AND A RIDGE ENCOMPASSES THE CENTRAL GULF OF MEXICO. IT WAS ANOTHER HOT DAY AS TEMPS SOARED INTO THE MID-UPPER 90S OVER INLAND AREAS. TEMPS HAVE COOLED SLIGHTLY SINCE, WITH READINGS IN THE 80S. DEW POINTS HAVE CREPT UP INTO THE LOWER 70S, MAKING IT FEEL A BIT UNCOMFORTABLE. THE 00Z TAE SOUNDING SHOWS NO CHANGE IN PRECIPITABLE WATER (1.5"). NORTHERLY WINDS FROM 700 TO 950 MB BECOME WESTERLY NEAR 500 MB UNDER INFLUENCE OF PASSING TROUGH. && .PUBLIC (TONIGHT)...REGIONAL RADARS SHOW MOST OF THE PRE-FRONTAL CONVECTION FADING AWAY WITH LOSS OF INSOLATION. WITH THAT IN MIND, WILL LOWER POPS TO SILENT 10'S FOR THE REMAINDER OF TONIGHT, AND AMEND ZONES TO REMOVE POPS FROM OUR AL AND GA ZONES. && .MARINE...WEST WINDS 5-10 KNOTS THIS EVENING, IN AGREEMENT WITH THE NAM AND RUC, VEER TO THE NORTHWEST OVERNIGHT AS THE SURFACE RIDGE EDGES SOUTHWARD IN RESPONSE TO THE APPROACHING FRONT. SEAS WILL REMAIN LESS THAN 2 FEET. && .AVIATION...A FEW RESIDUAL SHOWERS APPROACHING WESTERN PORTIONS OF SOUTHEAST ALABAMA NOT EXPECTED TO MAKE IT TO DOTHAN. MEANWHILE, WINDS ARE DYING DOWN TO 3 MILES PER HOUR OR LESS OVER SE ALABAMA AND SOUTHWEST/SOUTH CENTRAL GEORGIA BUT STILL HANGING NEAR 6 TO 8 MILES PER HOUR FROM THE WEST OVER THE FLORIDA PANHANDLE AND BIG BEND. ALL TERMINALS WILL DROP TO LIGHT/VARIABLE WITHIN THE NEXT HOUR. VSBYS FOR THE MOST PART RANGED 5-6 MILES TODAY. EXPECT MVFR CONDITIONS TO DEVELOP NEAR SUNRISE TOMORROW AT MOST TERMINALS AND ALONG TWEB ROUTES 112 AND 117 AS CONDITIONS CONTINUING TO MOISTEN UP. IFR CONDITIONS EXPECTED BRIEFLY AT DHN AND VLD. THEN EXPECT VFR CONDITIONS FROM MID MORNING THROUGH AFTERNOON. && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. && $$ PUBLIC/MARINE...JAMSKI AVIATION...LANIER fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PEACHTREE CITY GA 1100 AM EDT FRI SEP 16 2005 .UPDATE... SENDING ANOTHER UPDATE TO RAISE POPS ONCE AGAIN. AREA OF CONVECTION IN MS/AL IS PROGGED TO DISSIPATE BY THE RUC...BUT THE MESOETA HOLDS IT TOGETHER A LITTLE BETTER. SYNOPTIC AND MESOSCALE PARAMETERS LEAD ME TO BELIEVE THAT THE CONVECTION WILL MAKE IT THROUGH TO THE AFTERNOON. SURFACE HEATING SOUTH OF THE AREA OF CLOUDS AND CONVECTION CURRENTLY IN NORTHERN GEORGIA WILL ALLOW CAPES AND LI'S TO EASILY BE REALIZED...FROM 1000-2000 J/KG AND DOWN TO -3 TO -4C RESPECTIVELY. IN ADDITION...BECAUSE OF THE AREA OF CLOUDINESS...A THERMAL BOUNDARY WILL LIKELY SET UP...ADDING AN ADDITIONAL POTENTIAL TRIGGERING MECHANISM AS THE SURFACE CONTINUES TO HEAT. DEWPOINTS IN THE UPPER 60S AND LOWER 70S ACROSS CENTRAL AND SOUTHERN GEORGIA ARE EVIDENCE OF PLENTY OF MOISTURE...AND THERE IS A LARGE AREA OF DEWPOINT DEPRESSIONS ALOFT OF LESS THAN 5 DEGREES. UPPER JETS WILL LINE UP THIS AFTERNOON TO PUT THE GENERAL AREA OF THE SOUTHEASTERN UNITED STATES IN BOTH THE RIGHT ENTRANCE REGION OF THE EXITING JET AND THE LEFT EXIT REGION OF THE ENTERING JET...VERY FAVORABLE FOR LIFT...AND SHORTWAVE ENERGY AT MULTIPLE LEVELS ALOFT WILL ALSO CONTRIBUTE TO LIFT WITH DIFFERENTIAL POTENTIAL VORTICITY ADVECTION MAXIMIZED. THUS...AM INCLINED TO BELIEVE THAT THUNDER WILL BE LIKELY NORTH THIS AFTERNOON WITH CHANCES WELL WARRANTED IN SOUTHERN ZONES. ISOLATED SEVERE IS DEFINITELY A POSSIBILITY AS WELL AS THE SITUATION EVOLVES AND FURTHER MONITORING WILL BE NECESSARY INTO THE AFTERNOON HOURS. LOWERED TEMPERATURES SLIGHTLY IN THE NORTH TO ACCOUNT FOR CLOUD COVER...AND ADJUSTED SKY COVER AGAIN AS WELL. && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ TDP ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 325 PM CDT FRI SEP 16 2005 .SHORT TERM...TNGT THRU SUN NGT PRIMARY CONCERN WL BE SYS APCHG FOR WEEKEND. NIL WX ATTM WITH SW-NE ORIENTED SFC RDG FM OK INTO GRTLKS. HWVR 100+KT JET NOW EXITING WRN CONUS TROF THRU RCKYS. SHRT WV WHICH AS OFF CA CST YDA NOT PUSHING THRU UT AND SHOULD REACH MO VLY TMRW MRNG. DOMESTIC 12Z MDLS SIMILAR THRU 48 HRS BUT DVRG SGFNTLY BY EARLY NEXT WEEK. ALTHOUGH MAGNITUDE AND TIMING VARY...CANADIAN AND EURO MDLS AGREE WITH GFS HANDLING OF NEXT GRTLKS SHRT WV WHICH IS NOW ALG WA CST. NAM OUT OF PHASE AND WILL BE DISCOUNTED AND HAS NOT BEEN HANDLING THINGS WELL LATELY. APCHG UT SYS SHOULD RMN TO OUR W OVNGT BUT KINEMATIC AND THERMODYNAMIC FORCING CERTAINLY INCR SAT. ONLY LMTG FACTOR IS LACK OF MSTR DEPTH...BUT CONSIDERING ISENT LIFT AND MSTR TRANSPORT ALG 310K SFC WL ADD SLGT CHC/LOW CHC POPS FOR HIGH BASED LGT SHWRS NWRN PTNS. FA MAINLY UNDER SUBSIDENCE BHND DEPARTING SHRT WV SAT NGT...BUT THERE IS STILL SOME EVIDENCE OF ISENT LIFT ALBEIT MSTR STARVED SO WL LEAVE SLGT CHCS GOING INTO SUN MRNG. POTENTIAL FOR MORE SGFNT PCPN AND TSTMS INCRS SUN AFTN INTO MON HWVR. FNT SLOWLY CROSSES FA WITH MLCAPES AOA 2000 J/KG AND 0-6KM SHEAR AOA 40KTS DRNG PEAK HEATING SUN SO CONDITIONAL SVR THREAT CERTAINLY THERE IF AVBL INSTABILITY CAN BE REALIZED. GFS 305K SFC HAS LOW LVL JET FOCUSED INTO SRN IA SUN NGT SO ALTHOUGH IT VEERS WITH TIME...ENOUGH ISENT LIFT SHOULD BE PRESENT TO SUSTAIN CONVECTION AFT SUNSET. COULD GO SFC BASED MON AFTN AS WELL WITH SIMILAR SVR POTENTIAL...BUT THAT WL DEPEND ON RECOVERY TIME AND STRENGTH OR EVEN EXISTENCE OF SUN NGT MCS. HAVE BOOSTED POPS FURTHER THRU CHC CATEGORY BUT NOT CONFIDENT ENOUGH TO GO LIKELY QUITE YET. SAT HIGHS SOMEWHAT PROBLEMATIC...BUT NOT BIG CONCERN. BOTH FCST SOUNDINGS DO NOT MIX MUCH MORE THAN 875MB WITH TEMPS BLO 2KM +-1C FM TDA. NAM SOUNDINGS...WHICH HAVE SHOWN SLGT WRM BIAS...ONLY REACH WRMR GFS MOS IF NR SFC LYR SUPER-ADIABATIC. CURRENT KOFK LAPS/RUC SOUNDINGS SHOW MIXING ABV THAT LVL HWVR WHICH MAKES SENSE CONSIDERING DRY AMS SO NOT SURE WHICH DIRECTION TO LEAN. WL SPLIT THE DIFFERENCE ATTM WITH GUIDANCE BLEND AND LCL CLIMO ADJUSTMENTS. HIGHS SUN SHOULD BE A FEW DEGS ABV PERSISTENCE AHD OF FNT. FOLLOWED ADJUSTED BLEND FOR MINS. .LONG TERM...MON NGT THRU FRI NO SGFNT CONCERNS THIS PD BUT WL HAVE TO ADDRESS PCPN POTENTIAL FM PREVIOUSLY DRY FCST. FNT EXITS SRN FA BY MON EVE AND RMNDR OF MON NGT INTO TUE LOOKS DRY WITH UPR MS VLY HIGH PRESSURE IN PLACE. PERIODIC ISENT LIFT THEN RETURNS TUE NGT INTO WED NGT AHD OF SLOW MOVG FNT. CONFIDENCE DCRG ABT THIS TIME WITH LTL AGREEMENT WITH REGARD TO SFC LOW AND WRM FNTL PLACMENT ASSOCD WITH ILL-DEFINED SHRT WVS IN ACTIVE WLYS TO OUR N. RECENT GFS RUNS NOW GENERATING WRM ADVCTN PCPN AHD OF AND ALG FNT AS IT SLOWLY MAKES ITS WAY THRU IA THU/THU EVE. CNVRGNC AND MSTR RTRN QUESTIONABLE WITH WEAK FLOW HWVR. BLEND OF GFS AND ASSOCD ENSEMBLES ALG WITH ECMWF THEN SUGGEST THAT FNT WL STALL JUST TO OUR S WITH BACLIN ZN INCR...AND MAINLY AFFECTING SRN PTNS. THIS LOW CONFIDENCE RESULTED IN ADDING EXTENDED PD OF SLGT CHCS TO DRY FCST. GUIDANCE TRENDING WRMR DAYS 4-6 WHICH MAKES SENSE CONIDERING SLY FLOW AND H85 TEMPS. DID NOT JUMP ON TOO MUCH OF A SWING BUT DID RAISE A CATEGORY OR LESS. FNT SEEMS TO PUSH THRU FRI SO RETURNED TEMPS CLOSER TO CLIMO. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SMALL ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 945 PM EDT FRI SEP 16 2005 .SHORT TERM UPDATE...(OVERNIGHT). AT 013Z THE COOL FRONT HAD MOVED EAST OF OUR FORECAST AREA. LOW CLOUDS EXTENDED FROM SOUTHERN ILLINOIS THROUGH SOUTHERN AND CENTRAL INDIANA. FORECAST CONCERN FOR THE OVERNIGHT PERIOD WILL BE CLOUD COVER AND FOG. THE LOW CLOUDS SHOULD ADVECT SLOWLY SOUTHEAST OVERNIGHT BUT THERE HAS BEEN SOME EROSION ON THE SOUTH SIDE. WE EXPECT THESE CLOUDS TO REACH INTO SOUTH CENTRAL INDIANA AS WELL AS NORTH CENTRAL AND THE BLUEGRASS REGION OF KENTUCKY. WE WILL KEEP THE SOUTH MOSTLY CLEAR WITH PATCHY FOG. WILL RAISE TEMPERATURES A FEW DEGREES ACROSS SOUTH CENTRAL KENTUCKY. UPDATED FORECAST OUT BY 10:15 PM. PREVIOUS DISCUSSION BELOW. .SHORT TERM (TONIGHT THROUGH SATURDAY)... CURRENTLY...WATER VAPOR SHOWING STRONG SHORTWAVE OVER GREAT LAKES WITH WEAKER SHORTWAVE OVER WESTERN KY. SFC FRONTAL BOUNDARY EVIDENT ON THE VIS SATELLITE...EXTENDING FROM IN/OH BORDER SW TO WEST OF NASHVILLE. THESE FEATURES HAVE HELPED GENERATE A LINE OF SHOWERS MOVING EASTWARD ACROSS THE CWA ATTM. MOST RECENT ACARS DATA SHOWING LOW-LEVEL CAP AROUND 700MB AT SDF...SO DO NOT EXPECT SHOWERS AROUND THE METRO AREA TONIGHT. HOWEVER RUC SOUNDINGS AROUND LEX STILL SHOWING ABOUT 800 J/KG OF MLCAPE AND WITH LOW FREEZING LEVELS...EVEN A THUNDERSTORM IS POSSIBLE WITHIN LINE AS IT TRAVERSES EASTWARD. FRONT WILL PASS THROUGH THE CWA BY LATE EVENING...SHIFTING WINDS TO THE NORTHWEST. HAVE ENDED POPS OVER NW COUNTIES AND KEPT IN SLT CHC POPS IN OVER EASTERN TWO THIRDS OF CWA THROUGH THIS EVENING. CLOUDS WILL STICK AROUND FOR THE MOST PART OVERNIGHT AS MODELS INDICATE AMPLE LOW-LEVEL MOISTURE BENEATH SUBSIDENCE ALOFT. THIS WILL LOCK IN MOISTURE NEAR THE SURFACE SO FOG/MIST/DRIZZLE/STRATUS CERTAIN POSSIBILITIES OVERNIGHT. BUFKIT SOUNDINGS INDICATE CONDITIONS WILL STILL BE A BIT MIXY OVER THE EASTERN HALF OF THE CWA AS 850MB WINDS WILL BE AROUND 15 KTS BY MORNING. WINDS SHOULD BE LIGHTER TO THE WEST...SO WENT WITH PATCHY FOG OVER WESTERN HALF AND DRIZZLE OVER EASTERN HALF OF CWA. STRATUS AND MORNING FOG/MIST/DRIZZLE WILL LIKELY STICK AROUND THE AREA THROUGH MID-MORNING SATURDAY...AND WITH CLOUDS OVERNIGHT THIS WILL HELP KEEP THE TEMPS FROM DROPPING TOO MUCH OVERNIGHT. MAIN COLD AIR ADVECTION WORKS ITS WAY INTO REGION SATURDAY AFTERNOON AS SFC HIGH PRESSURE SLIDES OVERHEAD. STRATUS WILL BE SLOW TO DISSIPATE...SO WILL START WITH MOSTLY CLOUDY SKIES AND WILL BECOME PARTLY CLOUDY BY EVENING. LOW-LEVEL THICKNESSES AND CORRESPONDING MOS GUIDANCE INDICATE MID-TO-UPPER 70S FOR HIGHS TOMORROW...EXCEPT FOR NEAR THE TN BORDER WHICH COULD SEE 80 DEGREES FOR A HIGH ON SAT. HOWEVER...WILL COOL OFF QUICK TOMORROW AS SUN BEGINS TO SET...CREATING FALL-LIKE CONDITIONS. AL .LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... MOST LOCATIONS WILL SEE PRIMARILY DRY WEATHER THROUGHOUT THE LONG TERM. RAIN CHANCES WILL BE SMALL AND WILL BE DEPENDENT ON SLIGHT WEAKNESSES IN SURFACE AND UPPER RIDGING. MODELS IN A BIT MORE AGREEMENT TODAY REGARDING WEATHER MONDAY INTO TUESDAY...THOUGH THERE ARE SOME SIGNIFICANT DISAGREEMENTS THAT INTRODUCE A FAIR AMOUNT OF UNCERTAINTY INTO THE FORECAST. GEM/ECMWF/NOGAPS/NAM/OPERATIONAL GFS ALL BRING AN UPPER 5H SHORTWAVE TROF INTO THE LAKES AND A SURFACE COOL FRONT INTO THE MIDWEST MONDAY...WITH SCATTERED SHOWERS AND STORMS AHEAD OF THE FRONT. OPERATIONAL GFS TIME-HEIGHTS SHOW A FEW HOURS OF DEEPER RH AND GOOD UVV MONDAY EVENING IN OUR NORTHWEST. AS THIS FRONT TRIES TO PUSH EAST IT WEAKENS QUITE A BIT AND LOSES A LOT OF ITS IDENTITY BY TUESDAY. HOWEVER...IN CONTRAST...THE GFS ENSEMBLE KEEPS THE SURFACE RIDGE IN PLACE THROUGHOUT THE EARLY PART OF THE WEEK AND PREVENTS ANY PRECIPITATION FROM COMING INTO THE AREA. ENSEMBLE POPS REMAIN BELOW CLIMATOLOGY. THAT THE ENSEMBLE GFS STAYS DRY IS TROUBLESOME HOWEVER WITH OTHER MODELS SUGGESTING SOME SMALL THREAT OF PRECIPITATION WILL HAVE ISOLATED SHOWERS/STORMS IN THE FORECAST IN THE NORTHWEST PARTS OF THE AREA...ESPECIALLY OUR INDIANA COUNTIES...MONDAY AFTERNOON...SPREADING EASTWARD MONDAY NIGHT AND THEN ENDING TUESDAY WITH POPS NEVER RISING ABOVE LOW CHANCE. THIS LINES UP WELL WITH SURROUNDING OFFICES TOO. 13 && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 312 PM EDT FRI SEP 16 2005 .SHORT TERM (TONIGHT THROUGH SATURDAY)... CURRENTLY...WATER VAPOR SHOWING STRONG SHORTWAVE OVER GREAT LAKES WITH WEAKER SHORTWAVE OVER WESTERN KY. SFC FRONTAL BOUNDARY EVIDENT ON THE VIS SATELLITE...EXTENDING FROM IN/OH BORDER SW TO WEST OF NASHVILLE. THESE FEATURES HAVE HELPED GENERATE A LINE OF SHOWERS MOVING EASTWARD ACROSS THE CWA ATTM. MOST RECENT ACARS DATA SHOWING LOW-LEVEL CAP AROUND 700MB AT SDF...SO DO NOT EXPECT SHOWERS AROUND THE METRO AREA TONIGHT. HOWEVER RUC SOUNDINGS AROUND LEX STILL SHOWING ABOUT 800 J/KG OF MLCAPE AND WITH LOW FREEZING LEVELS...EVEN A THUNDERSTORM IS POSSIBLE WITHIN LINE AS IT TRAVERSES EASTWARD. FRONT WILL PASS THROUGH THE CWA BY LATE EVENING...SHIFTING WINDS TO THE NORTHWEST. HAVE ENDED POPS OVER NW COUNTIES AND KEPT IN SLT CHC POPS IN OVER EASTERN TWO THIRDS OF CWA THROUGH THIS EVENING. CLOUDS WILL STICK AROUND FOR THE MOST PART OVERNIGHT AS MODELS INDICATE AMPLE LOW-LEVEL MOISTURE BENEATH SUBSIDENCE ALOFT. THIS WILL LOCK IN MOISTURE NEAR THE SURFACE SO FOG/MIST/DRIZZLE/STRATUS CERTAIN POSSIBILITIES OVERNIGHT. BUFKIT SOUNDINGS INDICATE CONDITIONS WILL STILL BE A BIT MIXY OVER THE EASTERN HALF OF THE CWA AS 850MB WINDS WILL BE AROUND 15 KTS BY MORNING. WINDS SHOULD BE LIGHTER TO THE WEST...SO WENT WITH PATCHY FOG OVER WESTERN HALF AND DRIZZLE OVER EASTERN HALF OF CWA. STRATUS AND MORNING FOG/MIST/DRIZZLE WILL LIKELY STICK AROUND THE AREA THROUGH MID-MORNING SATURDAY...AND WITH CLOUDS OVERNIGHT THIS WILL HELP KEEP THE TEMPS FROM DROPPING TOO MUCH OVERNIGHT. MAIN COLD AIR ADVECTION WORKS ITS WAY INTO REGION SATURDAY AFTERNOON AS SFC HIGH PRESSURE SLIDES OVERHEAD. STRATUS WILL BE SLOW TO DISSIPATE...SO WILL START WITH MOSTLY CLOUDY SKIES AND WILL BECOME PARTLY CLOUDY BY EVENING. LOW-LEVEL THICKNESSES AND CORRESPONDING MOS GUIDANCE INDICATE MID-TO-UPPER 70S FOR HIGHS TOMORROW...EXCEPT FOR NEAR THE TN BORDER WHICH COULD SEE 80 DEGREES FOR A HIGH ON SAT. HOWEVER...WILL COOL OFF QUICK TOMORROW AS SUN BEGINS TO SET...CREATING FALL-LIKE CONDITIONS. AL .LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... MOST LOCATIONS WILL SEE PRIMARILY DRY WEATHER THROUGHOUT THE LONG TERM. RAIN CHANCES WILL BE SMALL AND WILL BE DEPENDENT ON SLIGHT WEAKNESSES IN SURFACE AND UPPER RIDGING. MODELS IN A BIT MORE AGREEMENT TODAY REGARDING WEATHER MONDAY INTO TUESDAY...THOUGH THERE ARE SOME SIGNIFICANT DISAGREEMENTS THAT INTRODUCE A FAIR AMOUNT OF UNCERTAINTY INTO THE FORECAST. GEM/ECMWF/NOGAPS/NAM/OPERATIONAL GFS ALL BRING AN UPPER 5H SHORTWAVE TROF INTO THE LAKES AND A SURFACE COOL FRONT INTO THE MIDWEST MONDAY...WITH SCATTERED SHOWERS AND STORMS AHEAD OF THE FRONT. OPERATIONAL GFS TIME-HEIGHTS SHOW A FEW HOURS OF DEEPER RH AND GOOD UVV MONDAY EVENING IN OUR NORTHWEST. AS THIS FRONT TRIES TO PUSH EAST IT WEAKENS QUITE A BIT AND LOSES A LOT OF ITS IDENTITY BY TUESDAY. HOWEVER...IN CONTRAST...THE GFS ENSEMBLE KEEPS THE SURFACE RIDGE IN PLACE THROUGHOUT THE EARLY PART OF THE WEEK AND PREVENTS ANY PRECIPITATION FROM COMING INTO THE AREA. ENSEMBLE POPS REMAIN BELOW CLIMATOLOGY. THAT THE ENSEMBLE GFS STAYS DRY IS TROUBLESOME HOWEVER WITH OTHER MODELS SUGGESTING SOME SMALL THREAT OF PRECIPITATION WILL HAVE ISOLATED SHOWERS/STORMS IN THE FORECAST IN THE NORTHWEST PARTS OF THE AREA...ESPECIALLY OUR INDIANA COUNTIES...MONDAY AFTERNOON...SPREADING EASTWARD MONDAY NIGHT AND THEN ENDING TUESDAY WITH POPS NEVER RISING ABOVE LOW CHANCE. THIS LINES UP WELL WITH SURROUNDING OFFICES TOO. 13 && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION..UPDATE.. NATIONAL WEATHER SERVICE TAUNTON MA 1240 PM EDT FRI SEP 16 2005 .UPDATE (THIS AFTERNOON)... SHOWERS CONTINUE ACROSS THE SOUTH COAST. MADE SOME COSMETIC CHANGES TO QPF AND POPS TO REFLECT THE BOUNDARY MOVING NORTH. RUC ONCE AGAIN HANDLING NEAR TERM VERY WELL AND WAS FOLLOWED CLOSELY FOR UPDATE. OPHELIA WARNING ISSUED FOR SOUTH COAST AND ADJACENT COASTAL WATER. NO OTHER CHANGES. MCJ && .PREVIOUS DISCUSSION ...OPHELIA WATCHES CONTD WITH 5AM PACKAGE AND IF WE GO TO A WARNING IT WILL BE WITH THE 11AM PKG... .HYDROLOGY... PNSBOX FOR RFALL TOTALS WILL GO THRU ANOTHER ITERATION AROUND 9AM FRIDAY FOR WDSPRD 2-4" TOTALS I95 CORRIDOR SEWD YDY. HOW TODAY THROUGH SAT UNFOLD IS STILL DEBATABLE BUT THIS FCSTR IS EXPECTING ADDITIONAL LARGE AMTS IN PARTS OF SNE BY 00Z SUN. THIS DUE TO FAIRLY DEEP SLY FLOW OF TROP PW ARD 1.75" WITH SUBTLE 1000-850 THICKNESS LIFT DUE TO THE LIGHT NE FLOW IN SNE. AS YOU CAN FROM RADAR.. THE REINJECTION CONNECTION TO OPHELIA SEEMS TO HAVE STARTED WITH GRADU INCREASE IN SHOWERS...SOME OF THEM HEAVY AS OF 11Z AND POISED TO WASH ASHORE FROM OFF OF ERN LI TO BID! I LIKE THE 09Z RUC FOR THE SHORT TERM IDEA. THEN LATE TONIGHT AND SAT MORNING MID LVL DEF ZONE RW+ BAND NR I95 AND OPEHLIA RW+ ALONG AND JUST E OF THE CENTER. THIS DROUGHT DENTING RAIN OF THE PAST 24 HRS WILL EVENTUALLY HAVE TOTAL AMTS IN PARTS OF SE NEW ENGLAND FM 12Z THU THRU 00Z SUN OF OVER 5"...MAYBE AS MUCH AS 7". GIVE US TIME TO EXPRESS CONFIDENCE ON THE ABV LATER THIS SHIFT. .SHORT TERM (FRIDAY THROUGH SATURDAY)... OPHELIA RELATED. WATCHES CONTD. 11AM WILL THE DECISION TIME FOR WARNING IF WE GO THAT ROUTE FOR ACK REGION. ALL STMTS ETC FOLLOW ARD 5AM. IN-HOUSE CK OF TPC PREDICTED WINDS SHOWS ABOUT 7-9 HRS OF 39 MPH OR HIGHER SUSTAINED WINDS FOR ACK-CHH-MVY STARTING ROUGHLY 4 AM AND ENDING ARD 1 PM.F DECISION ON 11AM WARNING (24HR LEAD TIME) IS THE EXTENT OF TS WIND FIELD ON NW SIDE OF THE STORM..WHICH IS SOMEWHAT IN DOUBT. HEAVY SURF ADVY POSTED. 5 FT SWELLS FM OPHELIA ARE PROGRESSING NWD INTO OUR CW INCLUDING MVY. NEW FFG NOT UPDATED TIL 14Z/16 WITH TODAYS HEAVY RAINS SO YDY GUIDANCE FM 14Z/15 IS NOT IDEAL TO USE. STILL ATTM NO FFA BUT MAY NEED TO ISSUE IN LATE MORNING PKG. SO...A COASTAL FLOOD...TSWRNG AND FFA ALL UNDER CONSIDERATION NEXT SHIFT. && .LONG TERM (SATURDAY NIGHT THROUGH THURSDAY)... ...RETURN TO DRY CONDITIONS BEGINNING SUNDAY AFTERNOON... OPHELIA DEPARTS THE COASTAL WATERS SATURDAY NIGHT FOLLOWED BY A TRAILING UPPER LEVEL SHORT WAVE DISTURBANCE. TRAILING SHORT WAVE CURRENTLY OVER ILLINOIS DOES NOT APPEAR QUITE AS AMPLIFIED AS IN PREVIOUS RUNS. IN FACT THE SHORT WAVE DAMPENS OUT WITH TIME AS IT TRACKS INTO THE NORTHEAST. THUS DECIDED TO LOWER POPS SUNDAY. WEAK HIGH PRESSURE WILL BUILD SUNDAY AFTERNOON AND MONDAY WITH DRYING CONDITIONS. A WEAK COLD FRONT ARRIVES MONDAY NIGHT BUT WITH LITTLE MOISTURE AND MOMENTUM TO WORK WITH. DECIDED TO DROP POPS TO SLIGHT CHANCE OVER NORTHERN LOCATIONS DURING THAT TIME FRAME. NEXT CHANCE OF SHOWERS MAY OCCUR LATE TUESDAY/WEDNESDAY MORNING. HOWEVER THIS FRONT WEAKENS WITH TIME AS WELL. DRY CONDITIONS WITH SEASONABLE TEMPERATURES WILL GENERALLY PREVAIL DURING THE EXTENDED TIME FRAME. && .AVIATION... CHAOTIC AVIATION CONDITIONS ETM WITH DENSE FOG IN PLACES. PLS SEE TAFS FOR DETAILS. && .MARINE... SWELLS FROM DISTANT HURRICANE OPHELIA ARE IMPACTING THE SOUTH COASTAL WATERS OF MA AND RI...PRIMARILY ACROSS THE OUTERMOST COASTAL WATERS. WILL CONTINUE THE SMALL CRAFT ADVISORIES FOR HAZARDOUS SEAS. SEAS WILL RISE SHARPLY AND EXTREMELY STEEP ACROSS THE FAR SOUTHEAST COASTAL WATERS SAT MORNING. THE BIG 17 FT WH GROUP WILL PROB ACCOMPANY OR TRAIL OPHELIA BY A COUPLE OF HRS ALONG AND E OF OPHELIAS TRACK. SEAS GRADU DIMINISH SAT NIGHT AND SUN. .CLIMO... RER FOR PVD SENT...2.66 INCHES FOR 9/15/05 BEATS DAILY RECORD OF 1.22 INCHES SET BACK IN 9/15/1999. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...TROPICAL STORM WARNING FOR MAZ019>024 UNTIL 10 PM MON. FLASH FLOOD WATCH MAZ018-019-022>024 TIL 6 PM FRIDAY. NH...NONE. RI...TROPICAL STORM WARNING FOR RIZ004-008 UNTIL 10 PM MONDAY. MARINE...TROPICAL STORM WARNING FOR ANZ231>237-254-255 UNTIL 10 PM MONDAY. ...GALE WARNING FOR ANZ250 FROM MIDNIGHT SATURDAY TO 4 PM SATURDAY. ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FOR ANZ250 UNTIL MIDNIGHT SATURDAY && $$ .SHORT TERM...DRAG .LONG TERM...STRAUSS ma AREA FORECAST DISCUSSION..UPDATE.. NATIONAL WEATHER SERVICE TAUNTON MA 713 AM EDT FRI SEP 16 2005 ...OPHELIA WATCHES CONTD WITH 5AM PACKAGE AND IF WE GO TO A WARNING IT WILL BE WITH THE 11AM PKG... .HYDROLOGY... PNSBOX FOR RFALL TOTALS WILL GO THRU ANOTHER ITERATION AROUND 9AM FRIDAY FOR WDSPRD 2-4" TOTALS I95 CORRIDOR SEWD YDY. HOW TODAY THROUGH SAT UNFOLD IS STILL DEBATABLE BUT THIS FCSTR IS EXPECTING ADDITIONAL LARGE AMTS IN PARTS OF SNE BY 00Z SUN. THIS DUE TO FAIRLY DEEP SLY FLOW OF TROP PW ARD 1.75" WITH SUBTLE 1000-850 THICKNESS LIFT DUE TO THE LIGHT NE FLOW IN SNE. AS YOU CAN FROM RADAR.. THE REINJECTION CONNECTION TO OPHELIA SEEMS TO HAVE STARTED WITH GRADU INCREASE IN SHOWERS...SOME OF THEM HEAVY AS OF 11Z AND POISED TO WASH ASHORE FROM OFF OF ERN LI TO BID! I LIKE THE 09Z RUC FOR THE SHORT TERM IDEA. THEN LATE TONIGHT AND SAT MORNING MID LVL DEF ZONE RW+ BAND NR I95 AND OPEHLIA RW+ ALONG AND JUST E OF THE CENTER. THIS DROUGHT DENTING RAIN OF THE PAST 24 HRS WILL EVENTUALLY HAVE TOTAL AMTS IN PARTS OF SE NEW ENGLAND FM 12Z THU THRU 00Z SUN OF OVER 5"...MAYBE AS MUCH AS 7". GIVE US TIME TO EXPRESS CONFIDENCE ON THE ABV LATER THIS SHIFT. .SHORT TERM (FRIDAY THROUGH SATURDAY)... OPHELIA RELATED. WATCHES CONTD. 11AM WILL THE DECISION TIME FOR WARNING IF WE GO THAT ROUTE FOR ACK REGION. ALL STMTS ETC FOLLOW ARD 5AM. IN-HOUSE CK OF TPC PREDICTED WINDS SHOWS ABOUT 7-9 HRS OF 39 MPH OR HIGHER SUSTAINED WINDS FOR ACK-CHH-MVY STARTING ROUGHLY 4 AM AND ENDING ARD 1 PM. DECISION ON 11AM WARNING (24HR LEAD TIME) IS THE EXTENT OF TS WIND FIELD ON NW SIDE OF THE STORM..WHICH IS SOMEWHAT IN DOUBT. HEAVY SURF ADVY POSTED. 5 FT SWELLS FM OPHELIA ARE PROGRESSING NWD INTO OUR CW INCLUDING MVY. NEW FFG NOT UPDATED TIL 14Z/16 WITH TODAYS HEAVY RAINS SO YDY GUIDANCE FM 14Z/15 IS NOT IDEAL TO USE. STILL ATTM NO FFA BUT MAY NEED TO ISSUE IN LATE MORNING PKG. SO...A COASTAL FLOOD...TSWRNG AND FFA ALL UNDER CONSIDERATION NEXT SHIFT. && .LONG TERM (SATURDAY NIGHT THROUGH THURSDAY)... ...RETURN TO DRY CONDITIONS BEGINNING SUNDAY AFTERNOON... OPHELIA DEPARTS THE COASTAL WATERS SATURDAY NIGHT FOLLOWED BY A TRAILING UPPER LEVEL SHORT WAVE DISTURBANCE. TRAILING SHORT WAVE CURRENTLY OVER ILLINOIS DOES NOT APPEAR QUITE AS AMPLIFIED AS IN PREVIOUS RUNS. IN FACT THE SHORT WAVE DAMPENS OUT WITH TIME AS IT TRACKS INTO THE NORTHEAST. THUS DECIDED TO LOWER POPS SUNDAY. WEAK HIGH PRESSURE WILL BUILD SUNDAY AFTERNOON AND MONDAY WITH DRYING CONDITIONS. A WEAK COLD FRONT ARRIVES MONDAY NIGHT BUT WITH LITTLE MOISTURE AND MOMENTUM TO WORK WITH. DECIDED TO DROP POPS TO SLIGHT CHANCE OVER NORTHERN LOCATIONS DURING THAT TIME FRAME. NEXT CHANCE OF SHOWERS MAY OCCUR LATE TUESDAY/WEDNESDAY MORNING. HOWEVER THIS FRONT WEAKENS WITH TIME AS WELL. DRY CONDITIONS WITH SEASONABLE TEMPERATURES WILL GENERALLY PREVAIL DURING THE EXTENDED TIME FRAME. && .AVIATION... CHAOTIC AVIATION CONDITIONS ETM WITH DENSE FOG IN PLACES. PLS SEE TAFS FOR DETAILS. && .MARINE... SWELLS FROM DISTANT HURRICANE OPHELIA ARE IMPACTING THE SOUTH COASTAL WATERS OF MA AND RI...PRIMARILY ACROSS THE OUTERMOST COASTAL WATERS. WILL CONTINUE THE SMALL CRAFT ADVISORIES FOR HAZARDOUS SEAS. SEAS WILL RISE SHARPLY AND EXTREMELY STEEP ACROSS THE FAR SOUTHEAST COASTAL WATERS SAT MORNING. THE BIG 17 FT WH GROUP WILL PROB ACCOMPANY OR TRAIL OPHELIA BY A COUPLE OF HRS ALONG AND E OF OPHELIAS TRACK. SEAS GRADU DIMINISH SAT NIGHT AND SUN. .CLIMO... RER FOR PVD SENT...2.66 INCHES FOR 9/15/05 BEATS DAILY RECORD OF 1.22 INCHES SET BACK IN 9/15/1999. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...TROPICAL STORM WATCH FOR MAZ019>024 UNTIL 4 PM SAT. ...HIGH SURF WARNING FOR MAZ020-022>024 UNTIL MIDNIGHT SATURDAY. NH...NONE. RI...TROPICAL STORM WATCH FOR RIZ005-007 UNTIL 4 PM SAT. ...HIGH SURF WARNING FOR RIZ006>008 UNTIL MIDNIGHT SATURDAY. MARINE...SMALL CRAFT ADVISORY FOR ANZ230-237-250 FROM MIDNIGHT SATURDAY TO 4 PM SATURDAY. ...TROPICAL STORM WATCH FOR ANZ231>236-254-255 UNTIL 4 PM SATURDAY. ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FOR ANZ235-237-250-254- 255 UNTIL MIDNIGHT SATURDAY. && $$ .SHORT TERM...DRAG .LONG TERM...STRAUSS ma AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 339 PM EDT FRI SEP 16 2005 .SHORT TERM...TONIGHT AND SATURDAY LOW/INVERTED SURFACE TROUGH OVER EASTERN GREAT LAKES REGION MAKING VERY SLOW PROGRESS EASTWARD TONIGHT AND SATURDAY WITH OPHELIA LIFTING NORTHEAST...FINALLY ALLOWING RIDGE TO BUILD IN DURING SATURDAY AND PROMOTING BETTER CLEARING. AT 500 MB...VORTICITY MAXIMUM...WELL INITIALIZED NEAR SOUTHERN TIP OF LAKE MI AS PER WATER VAPOR IMAGERY AT 12Z...MOVING ACROSS SOUTHEASTERN MI THIS AFTERNOON TO JUST SOUTH OF LAKE HURON BY 00Z. SECONDARY BUT VERY WEAK SHORTWAVE TROUGH MOVING IN LATE TONIGHT AND TO THE EAST SATURDAY. 850 TO 500 MB MOISTURE GOOD EARLY TONIGHT...ESPECIALLY NORTH...WANING OVERNIGHT AND BECOMING QUITE DRY SATURDAY. 925 MB MOISTURE PLENTIFUL TONIGHT...ESPECIALLY EARLY...SLOWLY DECREASING BUT STILL A FAIR AMOUNT LEFT ON SATURDAY. WEAK LOW TO MID LEVEL OMEGA LIFT HANGING ON TONIGHT IN THUMB...ESPECIALLY EARLY...OTHERWISE WEAK SUBSIDENCE SETTING IN BY TONIGHT AND PREVAILING THROUGH SATURDAY. MODEST SURFACE CONVERGENCE PERSISTING THROUGH TONIGHT VICINITY OF THE THUMB...IN CLOSER PROXIMITY TO EASTERN LAKES TROUGH. GOOD UPPER LEVEL DIVERGENCE OVER NORTHERN COUNTIES MUCH OF TODAY SHOULD BE GONE BY EARLY THIS EVENING. WILL KEEP SCATTERED LIGHT SHOWERS GOING IN THUMB TONIGHT...AND MENTION ALSO OVER MUCH OF REMAINDER OF NORTHERN COUNTIES EARLY THIS EVENING IN KEEPING WITH CURRENT DIMINISHING RADAR TRENDS. OTHERWISE...JUST MENTION OF EARLY EVENING SPRINKLES. && .LONG TERM...SATURDAY NIGHT THROUGH FRIDAY A MEAN TROUGH OVER WESTERN CANADA AND UPPER LOW CURRENTLY OVER THE PACIFIC NORTHWEST WILL BE THE MAIN FORECAST CHALLENGE LATE THIS WEEKEND INTO EARLY NEXT WEEK. THE UPPER LOW WILL CONTINUE TO DROP INTO THE NORTHWESTERN US... WHILE A NORTHERN STREAM TROUGH RACES ACROSS SOUTHERN CANADA. THIS TROUGH WILL SEND AN ASSOCIATED COLD FRONT INTO THE NORTHWESTERN GREAT LAKES REGION BY SUNDAY. MEANWHILE... THE CIRCULATION OVER THE PACIFIC NORTHWEST WILL DEVELOP INTO A DEEP UPPER LOW OVER CENTRAL CALIFORNIA BY MONDAY. THE GFS/ECMWF/CANADIAN SOLUTIONS ALL SHOW A SHORT WAVE EJECTING OUT OF THIS SYSTEM AND MOVING ACROSS THE NORTHERN TIER US ON SUNDAY. THIS SHORT WAVE EVENTUALLY REACHES THE GREAT LAKES REGION BY MONDAY...ALLOWING A SURFACE LOW TO DEVELOP ALONG THE FRONTAL BOUNDARY AND TRACK ACROSS LOWER MICHIGAN. THE NAM/WRFXX HOWEVER DO NOT SHOW THIS SHORT WAVE MOVING INTO THE REGION... AND THUS ONLY SHOW A WEAK FRONTAL BOUNDARY PASSING ACROSS THE STATE ON MONDAY. WITH THE GFS SOLUTION HAVING INITIALIZED UPSTREAM WAVES MORE REALISTICALLY AND GIVEN THE CONTINUITY SEEN IN THE GFS/ECMWF/CANADIAN... PREFER THEIR SOLUTION. THE GFS DOES HAVE SOME CONVECTIVE FEEDBACK ISSUES...WHICH LIKELY LEADS TO OVERDEVELOPMENT OF THE SURFACE LOW. WILL STILL HOWEVER PLAN ON A SHORT WAVE INTERACTING WITH STRONG MOISTURE TRANSPORT AHEAD OF THE SURFACE FRONT AND MAINTAIN A CHANCE OF SHOWERS AND THUNDERSTORMS MONDAY INTO EARLY TUES. A FAST AND ZONAL FLOW ALOFT STILL LOOKS LIKE IT WILL DEVELOP ACROSS THE NORTHERN TIER OF THE US BY MID WEEK AS THE UPPER RIDGE PERSISTS ACROSS THE SOUTHERN PLAINS. THE ECMWF HAS CONSISTENTLY SHOWN THE PATTERN TO BECOME MORE AMPLIFIED TOWARD THE END OF THE WEEK AS A TROUGH DIVES INTO WESTERN CANADA AND THE NORTHWESTERN US... WITH RISING HEIGHTS ACROSS THE EASTERN US. THE 00Z CANADIAN AND 12Z GFS SEEM TO BE FOLLOWING SUIT WITH THIS TREND. WILL THUS FORECAST TEMPS ABOVE CLIMO DURING THE LATER HALF OF THE WEEK. TIMING OF SHORT WAVE ENERGY LIFTING INTO THE GREAT LAKES WITHIN THE SOUTHWEST FLOW STILL REMAINS PROBLEMATIC... WITH LARGE SPREADS STILL EVIDENT AMONG ENSEMBLE MEMBERS AND VARIOUS MEDIUM RANGE SOLUTIONS. THE OPERATIONAL GFS IS INDICATING THE BEST CHANCE FOR CONVECTION TO BE ON THURSDAY. AT THIS POINT... WILL KEEP THE FORECAST DRY UNTIL ENSEMBLE MEMBERS AND VARIOUS MODELS CONVERGE A LITTLE MORE ON A SOLUTION. && .AVIATION... ISSUED AT 222 PM A POTENT SHORTWAVE MOVING ACROSS LOWER MICHIGAN HAS AND WILL CONTINUE TO MAKE FOR A CHALLENGING AVIATION FORECAST. AN EXTENSIVE AREA OF LOW CLOUDS...STRETCHING FROM EXTREME SOUTHERN LOWER MICHIGAN ALL THE WAY BACK DOWN TO SOUTHEAST MISSOURI...NORTHERN ARKANSAS...HAS BECOME TRAPPED BENEATH A STRENGTHENING SUBSIDENCE INVERSION. CURRENT SURFACE OBS REVEAL THE BULK OF THIS STRATUS TO BE UNDER 1000 FEET. THE DETROIT AREA HAS BEEN JUST ON THE NORTHERN OUTSKIRTS OF THIS IFR DECK...REMAINING PRIMARILY AT MVFR CEILINGS AROUND 2500 FEET. THE 12Z NAM AND RUC BOTH SHOW IFR CEILINGS AT THE DETROIT TERMINALS INTO THE EARLY EVENING HOURS. BASED ON UPSTREAM OBS...THIS SEEMS LIKELY BUT STILL HAS NOT HAPPENED AS OF 2 PM. A TIGHTER GRADIENT NEAR DETROIT IN CLOSER PROXIMITY TO THE SURFACE LOW HAS RESULTED IN WINDS GUSTING AS HIGH AS 20 MPH THIS AFTERNOON. THIS HAS HELPED TO KEEP THE LOWER STRATUS CLOUDS FROM SETTLING IN. THE LOW WILL CONTINUE TO PULL OFF TO THE EAST TODAY. THIS SHOULD ALLOW THE WINDS AT DTW AND DET TO SUBSIDE ENOUGH FOR LIFR CLOUDS TO EVENTUALLY PREVAIL THROUGH THE EVENING. SCATTERED LIGHT RAIN SHOWERS AND DRIZZLE THIS AFTERNOON WILL RESULT IN OCCASIONAL MVFR VISIBILITIES AS WELL. DRIER AIR NORTH OF DETROIT WILL HELP KEEP FNT ABOVE IFR. OCCASIONAL MVFR CONDITIONS ARE EXPECTED IN LIGHT RAIN SHOWERS THIS AFTERNOON...AND THEN AGAIN OVERNIGHT AS LOWER LEVEL MOISTURE CONTINUES TO BUILD IN FROM THE SOUTHWEST. SAGINAW LOOKS TO BE FAR ENOUGH NORTH TO REMAIN AT VFR CEILINGS. OCCASIONAL MVFR VISIBILITIES ARE EXPECTED THIS AFTERNOON IN RAIN SHOWERS. THE STRATUS DECK IS EXPECTED TO HANG ON LONG ENOUGH OVERNIGHT TO PREVENT GOOD RADIATIONAL COOLING AND DENSE FOG DEVELOPMENT. SAGINAW WILL HAVE THE BEST CHANCE OF FOG AS DRIER AIR WORKS IN FROM THE NORTH. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON...UNTIL 6 AM SATURDAY. LAKE ST CLAIR...SMALL CRAFT ADVISORY...UNTIL 6 PM THIS EVENING. MI WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY...UNTIL 6 PM THIS EVENING. && $$ SHORT TERM...DWD LONG TERM....CONSIDINE AVIATION...SHULER mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 330 PM EDT FRI SEP 16 2005 .DISCUSSION... MAIN FCST ISSUES ARE PCPN CHANCES SAT NIGHT THRU MON. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A GENERAL WSW FLOW ACROSS THE CONUS. A PROMINENT SHORTWAVE WAS LIFTING INTO THE ERN GREAT LAKES. UPSTREAM...A MINOR SHORTWAVE EXTENDING FROM MT TO SRN MN HAD PRODUCED A FEW -SHRA AND AN ISOLD TSRA OVER ERN SD EARLIER TODAY. FARTHER UPSTREAM...A STRONGER SHORTWAVE WAS OVER SRN NV AND A CLOSED MIDLEVEL LOW WAS OVER WRN WA. THE SHORTWAVE OVER SRN NV WILL BRING THE FIRST POTENTIAL OF PCPN TO THE FCST AREA SAT NIGHT. VIS SATELLITE IMAGERY REVEALS BASICALLY CLR SKIES OVER THE FCST AREA THIS AFTN WITH ONLY A SCATTERING OF CU OVER PARTS OF THE W HALF OF UPPER MI AND SOME CI OVER THE FAR E. WITH FULL SUN...TEMPS HAVE REACHED THE MID 70S AT MANY REPORTING STATIONS. UNTIL NV SHORTWAVE ARRIVES SAT NIGHT...DRY WEATHER WILL PREVAIL ACROSS UPPER MI. WEAK SHORTWAVE THAT PRODUCED A FEW SHRA/TSRA OVER ERN SD WILL LIFT NE AND NOT BE FACTOR HERE AS DRY AIR HOLDS OVER THE AREA (NOTE 12Z KMPX SOUNDING WHICH SHOWED A DRY PROFILE BELOW 750MB). THE LAYER OF MOISTURE SHOWN ON KMPX SOUNDING FROM 550-700MB AND REVEALING ITSELF AS SOME MID CLOUDS OVER WCNTRL WI PER SATELLITE IMAGERY MAY RESULT IN A FEW CLOUDS TONIGHT...BUT NOT ENOUGH TO PRECLUDE MOSTLY CLEAR WORDING ACROSS THE BOARD. THE SLIGHTLY COOLER GFS MOS MINS ARE PREFERRED DUE TO LACK OF CLOUDS AND LIGHT/CALM WIND. EXPECT A WARM DAY FOR MID SEPT ON SAT AS S TO SW FLOW CONTINUES TO BRING WARMER AIR INTO THE AREA. MIXING TO AROUND 850MB ON GFS/NAM FCST SOUNDINGS YIELDS HIGHS INTO THE MID/UPPER 70S (WILL BE A FEW DEGREES COOLER NEAR LAKE MICHIGAN WITH SRLY FLOW). WOULD NOT BE SURPRISED TO SEE A FEW SPOTS REACH 80 (RECORD FOR SAT AT KMQT IS 82). MODELS SHOW DECENT ISENTROPIC ASCENT AT THE MID LEVELS SAT ESPECIALLY OVER THE W...BUT CONDENSATION PRES DEFICITS ARE QUITE HIGH. SKIES WILL PROBABLY TREND PARTLY SUNNY OVER THE W WHERE STRONGER ASCENT IS INDICATED...BUT REMAIN MOSTLY SUNNY E. SAT NIGHT...ATTENTION FOCUSES ON SHORTWAVE CURRENTLY OVER NV. NAM/GFS ARE IN GOOD AGREEMENT SHOWING THIS WAVE REACHING WRN LAKE SUPERIOR LATE SAT NIGHT. MODEST 850MB THETA-E ADVECTION IS INDICATED OVER THE W...BUT FCST SOUNDINGS STILL DON'T REVEAL MUCH FOR ELEVATED CAPE (NAM IS HIGHEST AT UP TO A FEW HUNDRED J/KG). NONETHELESS... POTENTIAL OF SOME ELEVATED CONVECTION IS STILL SUFFICIENT TO RETAIN GOING LOW RANGE CHC POPS OVER ABOUT THE W HALF OF FCST AREA SAT NIGHT. STRONGER NRN STREAM SHORTWAVE HEADS ACROSS ONTARIO SUN...PUSHING COLD FRONT ACROSS UPPER MI. MODELS SHOW SIMILAR TIMING OF FRONT... REACHING WRN FCST AREA LATE SUN MORNING AND EXITING THE E LATE AFTN/EARLY EVENING. GFS AND NAM ALSO SHOW MLCAPE RISING TO 400-700J/KG AHEAD OF FRONT. SO...EXPECT BEST CHC OF SHRA/TSRA TO BE OVER THE E HALF AS FROPA WILL OCCUR DURING WARMEST PART OF THE AFTN...BUT EVEN THERE...WILL ONLY UTILIZE MIDRANGE CHC POPS AS FORCING IS NOT STRONG. ALTHOUGH DEEP LAYER SHEAR IS UPWARDS OF 30KTS...LIMITED CAPE SHOULD PRECLUDE SVR STORMS. PCPN WILL END FROM W TO E WITH FROPA. ON MON...CONCERN WILL BE ON ENERGY ORIGINATING FROM MIDLEVEL LOW CURRENTLY OVER WRN WA. AS ALLUDED TO YESTERDAY...MEDIUM RANGE MODELS WERE TRENDING TOWARD TAKING THIS ENERGY EWD AND DEVELOPING AN ASSOCIATED SFC WAVE THAT LIFTS ENE INTO THE GREAT LAKES ALONG THE COLD FRONT THAT PASSES SUN. 00Z/12Z ECMWF BECOME QUITE WRAPPED UP WITH THE SFC LOW AS IT MOVES TO NRN LAKE MI BY MON EVENING. AT THIS POINT...PREFER A MORE SUPPRESSED/WEAKER SFC LOW SIMILAR TO 12Z GFS/CANADIAN AS UPPER AIR PATTERN ACROSS CONUS IS NOT SUPPORTIVE OF MUCH SHORTWAVE AMPLIFICATION OVER THE GREAT LAKES. HAVING SAID THAT...THE GFS APPEARS TO BRING TOO MUCH PCPN TOO FAR N. FOR NOW... WILL STAY ALONG THE LINES OF GOING FCST WHICH HAS LOW CHC POPS OVER ROUHGLY THE SRN FCST AREA. SHOULD BE A CHILLY NIGHT MON NIGHT AS SFC HIGH PRES SETTLES OVER WRN UPPER MI BY 12Z TUE. MINS INTO THE MID/UPPER 30S SEEM QUITE POSSIBLE AT THE USUAL COLD SPOTS IN THE INTERIOR W HALF OF FCST AREA. TUE-FRI...00Z GFS/CANADIAN/ECMWF/UKMET ARE IN REASONABLE AGREEMENT FOR THIS PERIOD CONSIDERING THE FAST FLOW ACROSS SRN CANADA. DURING THE LAST COUPLE OF DAYS...ONE POSSIBLE PCPN EVENT WAS SUGGESTED BY THE MODELS FOR A BRIEF PERIOD IN THE TUE/WED TIME FRAME...THOUGH MODELS WERE TRENDING TOWARD A DRY SOLUTION. SHORTWAVE IN QUESTION IS STILL INDICATED BY THE VARIOUS MODELS PASSING ACROSS ONTARIO TUE NIGHT...BUT 00Z/06Z GFS ARE BY FAR THE MOST NRLY SOLUTIONS. EVEN WITH THE OTHER FARTHER S SOLUTIONS...BULK OF FORCING STILL REMAINS N OF FCST AREA...AND THERE IS REALLY NO CHANCE FOR MEANINGFUL MOISTURE RETURN. WILL THUS ONLY RETAIN SLIGHT CHC POPS FROM ISLE ROYALE ACROSS NRN LAKE SUPERIOR...AND DROP THE SLIGHT CHC POPS FROM THE REST OF THE AREA TUE NIGHT/WED MORNING. ECMWF/06Z GFS HAVE SURPRISINGLY SIMILAR TIMING FOR NEXT SHORTWAVE ARRIVING THU AND WILL INTRODUCE POPS FOR THU/THU NIGHT (WOULD EXPECT TO SEE TIMING ISSUES DEVELOP IN LATER RUNS THOUGH). TEMPS THRU THE PERIOD SHOULD AVERAGE A LITTLE ABOVE NORMAL. && .MQT...WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 222 PM EDT FRI SEP 16 2005 .AVIATION... A POTENT SHORTWAVE MOVING ACROSS LOWER MICHIGAN HAS AND WILL CONTINUE TO MAKE FOR A CHALLENGING AVIATION FORECAST. AN EXTENSIVE AREA OF LOW CLOUDS...STRETCHING FROM EXTREME SOUTHERN LOWER MICHIGAN ALL THE WAY BACK DOWN TO SOUTHEAST MISSOURI...NORTHERN ARKANSAS...HAS BECOME TRAPPED BENEATH A STRENGTHENING SUBSIDENCE INVERSION. CURRENT SURFACE OBS REVEAL THE BULK OF THIS STRATUS TO BE UNDER 1000 FEET. THE DETROIT AREA HAS BEEN JUST ON THE NORTHERN OUTSKIRTS OF THIS IFR DECK...REMAINING PRIMARILY AT MVFR CEILINGS AROUND 2500 FEET. THE 12Z NAM AND RUC BOTH SHOW IFR CEILINGS AT THE DETROIT TERMINALS INTO THE EARLY EVENING HOURS. BASED ON UPSTREAM OBS...THIS SEEMS LIKELY BUT STILL HAS NOT HAPPENED AS OF 2 PM. A TIGHTER GRADIENT NEAR DETROIT IN CLOSER PROXIMITY TO THE SURFACE LOW HAS RESULTED IN WINDS GUSTING AS HIGH AS 20 MPH THIS AFTERNOON. THIS HAS HELPED TO KEEP THE LOWER STRATUS CLOUDS FROM SETTLING IN. THE LOW WILL CONTINUE TO PULL OFF TO THE EAST TODAY. THIS SHOULD ALLOW THE WINDS AT DTW AND DET TO SUBSIDE ENOUGH FOR LIFR CLOUDS TO EVENTUALLY PREVAIL THROUGH THE EVENING. SCATTERED LIGHT RAIN SHOWERS AND DRIZZLE THIS AFTERNOON WILL RESULT IN OCCASIONAL MVFR VISIBILITIES AS WELL. DRIER AIR NORTH OF DETROIT WILL HELP KEEP FNT ABOVE IFR. OCCASIONAL MVFR CONDITIONS ARE EXPECTED IN LIGHT RAIN SHOWERS THIS AFTERNOON...AND THEN AGAIN OVERNIGHT AS LOWER LEVEL MOISTURE CONTINUES TO BUILD IN FROM THE SOUTHWEST. SAGINAW LOOKS TO BE FAR ENOUGH NORTH TO REMAIN AT VFR CEILINGS. OCCASIONAL MVFR VISIBILITIES ARE EXPECTED THIS AFTERNOON IN RAIN SHOWERS. THE STRATUS DECK IS EXPECTED TO HANG ON LONG ENOUGH OVERNIGHT TO PREVENT GOOD RADIATIONAL COOLING AND DENSE FOG DEVELOPMENT. SAGINAW WILL HAVE THE BEST CHANCE OF FOG AS DRIER AIR WORKS IN FROM THE NORTH. && .UPDATE...ISSUED 1201 PM PRONOUNCED MID LEVEL VORTICITY MAXIMUM...AS DEPICTED VIA WATER VAPOR IMAGERY...STILL TO ROTATE THROUGH THIS AFTERNOON...THOUGH SHOWER COVERAGE ON RADAR HAS DIMINISHED SOMEWHAT AND IS LARGELY CONFINED TO THE NORTH OF INTERSTATE 94. HAVE UPDATED FOR SCATTERED SHOWERS THIS AFTERNOON...EXCEPT FOR MORE NUMEROUS IN THE THUMB...AND SMALLER CHANCE LIGHT SHOWERS WITH AREAS OF DRIZZLE IN FAR SOUTH. A SOUPY LOW CLOUD TYPE OF AFTERNOON EXPECTED...WHICH WILL LIMIT HEATING. THUS...HAVE LOWERED TEMPERATURES SEVERAL DEGREES IN MOST AREAS. && .SHORT TERM...FRIDAY AND FRIDAY NIGHT...ISSUED AT 337 AM EDT WATER VAPOR IMAGERY SHOWS A WELL DEFINED SYSTEM AFFECTING THE AREA EARLY THIS MORNING. STRONG ISENTROPIC ASCENT ON THE LEADING EDGE OF THIS DISTURBANCE IS SPREADING AN AREA OF LIGHT/MODERATE RAIN NORTH THROUGH THE CWA ATTM. THIS AREA PUSHES THROUGH THE SOUTHERN 1/2 OF THE AREA EARLY THIS MORNING...AND IS BY AND LARGE EAST OF THE REGION BY DAYBREAK OR SHORTLY THEREAFTER. DEFORMATION ZONE THAT EXTENDS FROM SOUTHWEST LOWER MICHIGAN BACK TO THE WISCONSIN/ILLINOIS BORDER WILL THEN TRAVERSE PORTIONS OF THE AREA ON FRIDAY MORNING...WITH A FEW SHOWERS LINGERING INTO THE AFTN. GIVEN SATELLITE/RADAR REPRESENTATION...WILL UP POPS TO CATEGORICAL (80-90%) SOUTH...AND EXPAND THE REMAINING LIKELY AREA NORTH PAST INTERSTATE 69...BUT LIMIT THESE HIGH RANGE POPS TO THE MORNING. THEREAFTER...SYSTEM MOVES STEADILY TO THE EAST...LEAVING JUST SPOTTY SHOWERS DURING THE AFTERNOON INTO THE EARLY EVENING. WILL HAVE TO WATCH THE SOUTHERN EDGE OF THE CWA...WHERE DRY SLOT MAY LIMIT WIDESPREAD RAINFALL BY DAYBREAK. FOR NOW...WILL LEAVE AS 80% CHANCE OF RAIN THROUGH THE MORNING. TEMPERATURES TO BE ON THE COOL SIDE TODAY WITH THE CLOUD COVER AND RAINFALL...AND THEN AGAIN TONIGHT AS SKIES CLEAR TO SOME DEGREE AND AREA REMAINS IN RELATIVELY COOL POCKET OF AIR JUST IN BEHIND THE SYSTEM WHICH IS BEGINNING TO PHASE WITH OPHELIA BY THAT TIME. THE TEMPERATURES WILL DO NO BETTER THE THE 60S TODAY IN MOST AREAS WITH PERHAPS JUST THE SAGINAW VALLEY TOUCHING 70 (AWAY FROM MAIN BRUNT OF THE CLOUDS/RAIN). TONIGHT...50-55 IN MANY AREAS...WITH SPORADIC LOWS IN THE 45-50 RANGE IN RURAL VALLEYS...ETC. WILL TREND FROM CLOUDY TO PARTLY CLOUDY OVERNIGHT AS AFOREMENTIONED PHASING OF LOW PRESSURE WILL HOLD UP THE WORKS SOMEWHAT...AND DELAY A FULL SCALE CLEARING UNTIL SATURDAY. && .LONG TERM...SATURDAY THROUGH THURSDAY...ISSUED AT 337 AM EDT THE LONG TERM ASPECT OF THIS FORECAST WILL BE THE TRACK AND STRENGTH OF SHORT WAVE(S) AS SPLIT FLOW IS EXPECTED TO BECOME MORE ZONAL NEXT WEEK. AS PREVIOUSLY MENTIONED...LINGERING MID LEVEL MOISTURE OVER EASTERN HALF OF THE STATE OF MICHIGAN PER GFS/NAM AND SOME POTENTIAL FOR STRATO CU OFF LAKE HURON SHOULD KEEP SOME CLOUDS AROUND ON SATURDAY. HOWEVER...SUBSIDENCE BEHIND THE DEPARTING WAVE SHOULD ALLOW FOR PLENTY OF BREAKS IN THE OVERCAST BY LATE MORNING. WITH LAKE HURON TEMPERATURES AVERAGING IN THE UPPER 60S ALONG WITH THE NORTHEAST FLOW...WILL THUS FOLLOW THE SLIGHTLY COOLER 00Z GFS MOS MAX TEMPS. THE BUILDING HEIGHTS ALOFT AND SURFACE HIGH BUILDING INTO THE STATE...A QUIET AND COOL SATURDAY NIGHT AND WE SHOULD SEE DECENT RADIATIONAL COOLING. A WEAKENING COLD FRONT AND ASSOCIATED 500MB SHORT WAVE APPROACHES THE REGION ON SUNDAY WITH SHORT RANGE ENSEMBLES IN FAVOR OF THE NORTHERN POSITION OF THIS FRONT...THEREFORE KEEPING THE CWA DRY THROUGH SUNDAY. WE DO EXPECT A LITTLE BIT MORE IN THE MID LEVEL CLOUD COVER BUT A PTCLOUDY SKY SHOULD SUFFICE. CLOUD COVER AND RESIDUAL SURFACE WIND COMPONENT OFF OF LAKE HURON...WE WILL SHAVE OFF A COUPLE OF DEGREES ACROSS THE NORTHERN COUNTIES AND ADJACENT LAKE HURON COUNTIES WITH UPPER 70S INLAND AND SOUTHERN COUNTIES. NOW NEXT WEEK WILL BE INTERESTING TO WATCH AS WE MONITOR THE TROPICS AND WHICH SHORT WAVE EMBEDDED IN THE NORTHERN STREAM AND RESULTANT AMPLIFICATION BRINGS OUT THE NEXT CHANCE FOR RAIN. RECENT TREND IN THE GFS PER DPROG/DT FOR MONDAY NIGHT TUESDAY IS MORE AMPLIFICATION WHICH IS IN CLOSER AGREEMENT WITH THE THU-18Z DGEX. THIS BRINGS ABOUT WARM ADVECTION AND THE CHANCE FOR CONVECTION MONDAY INTO MONDAY NIGHT. GIVEN THE TREND TOWARD AMPLIFICATION...THIS SHOULD SLOW DOWN THE PROGRESS OF THIS SYSTEM SOMEWHAT WITH LINGERING CHANCE FOR LIGHT RAIN SHOWERS ON TUESDAY MORNING. THEREAFTER...ANOTHER RETURN TO RIDGING ALOFT AND HIGHER SURFACE PRESSURES THROUGH MID WEEK. ANOTHER COLD FRONT ATTEMPTS TO APPROACH ON THURSDAY YET ENSEMBLE MEMBERS ARE QUITE SIMPLY ALL OVER THE MAP AND PREFER TO STAY THE COURSE WITH CLIMATOLOGY (DRY) AT THIS TIME. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS...6 PM TO 6 AM THIS EVENING AND TONIGHT. LAKE ST CLAIR...SMALL CRAFT ADVISORY...UNTIL 6 PM FRIDAY. MI WATERS OF LAKE ERIE...SMALL CRAFT ADVISORY...UNTIL 6 AM SATURDAY. && $$ AVIATION.....SHULER UPDATE...DWD SHORT TERM...DG LONG TERM....BGM HTTP://WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1215 PM EDT FRI SEP 16 2005 .DISCUSSION...UPDATED ZONES/GRIDS ALREADY OUT. LOWERED TEMPS BY A FEW DEGREES ACROSS EASTERN HALF OF FORECAST AREA DUE TO ABUNDANT CLOUDINESS. OTHERWISE WITH THE EXCEPTION OF A FEW TWEAKS FOR CURRENT TRENDS...REMAINDER OF THE FORECAST APPEARS TO BE ON TRACK. SYSTEM TO OUR SOUTH IS BRINGING RAIN SHOWERS TO SOUTHERN AND EASTERN ZONES (WHICH IS FARTHER NORTH THAN ANY OF US THOUGHT YESTERDAY). SULLIVAN .PREV DISCUSSION ISSUED 445 AM SEP 16 DISCUSSION...SFC MAP...SATELLITE AND RUC ANALYSIS AT 08Z SHOWS HIGH PRESSURE ACROSS EASTERN UPPER AND NRN WI...SANDWICHED BETWEEN TWO SFC LOWS. ONE OF WHICH IS TO OUR NW...IN WESTERN ONTARIO WHERE A WEAK COOL FRONT WAS DRAPED FROM THE LOW THROUGH SRN ND. THE OTHER SYSTEM WAS IN THE SRN IL VICINITY WITH PARENT SHORTWAVE MOVING THROUGH NE IL/CHICAGO VICINITY. THIS LOW PRESSURE HAS MUCH MORE MOISTURE TO WORK WITH...AS A THICK DECK OF MID AND HIGH CLOUD WAS INVADING ALL OF NRN LOWER. THE DEEPER MOISTURE WAS STILL WELL SOUTH OF THE CWA...IN THE MKG...GRR...FNT AND DTW AREAS. LIGHT SHOWERS AND SPRINKLES WERE IMPOSING UPON THE SRN TIER OF THE CWA...BUT CEILINGS REMAINED 10KFT OR HIGHER. FORECAST CONCERNS...PRECIP CHANCES TODAY AND EXTENT OF CLOUDY SKIES AND THEIR EFFECT ON HIGH TEMPS. AFTERWARDS...TIMING THE CLEARING FOR TONIGHT...THEN TRYING TO DISCERN HOW THE NEXT SYSTEM AND FRONTAL ZONE WILL BEHAVE FROM SUNDAY AFTERNOON THROUGH MONDAY NIGHT. TODAY...GFS CONTINUES TO BE THE MODEL HANDLING THE SITUATION MOST CORRECTLY...AS USUAL. LOOK FOR CLOUDS TO CONTINUE STREAMING IN FROM THE SOUTH THROUGH THE MORNING WHILE THE DEEP NE FLOW KEEPS THE SUB 10KFT LAYER RELATIVELY DRY. DO NOT FORESEE CEILINGS DROPPING BELOW 8KFT ANYWHERE IN THE CWA EXCEPT FOR MAYBE ARENAC/GLADWIN COUNTIES. AFOREMENTIONED PRECIP SHIELD WILL EXPAND INTO A GOOD PORTION OF THE SRN CWA IN ASSOCIATION WITH MODERATE H8-H5 -DIVQ AND IN LINE WITH LATEST RADAR TRENDS...BUT DOES NOT LOOK TO PASS NORTH OF M-32. WILL CARRY SPRINKLES FOR THE M-32 CORRIDOR WITH SCATTERED LIGHT SHOWERS SOUTH OF THIS AREA. THIS PRECIP SHIELD WILL SHUNT EASTWARD WITH PARENT SHORTWAVE TROUGH BY EARLY-MID AFTERNOON WHILE SKIES DECREASE IN CLOUDS FROM THE WEST. AXIS OF SFC HIGH PRESSURE ACROSS FAR NW LOWER AND EASTERN UPPER WILL KEEP SKIES PARTLY SUNNY...ONLY SEEING SOME HIGH CLOUD IN THE MORNING THEN SOME AFTERNOON CU. WILL HAVE LIGHT LAKE BREEZES DEVELOPING FOR THESE AREAS WHERE WINDS WILL BE LESS INFLUENCED BY NE GRADIENT TO THE SOUTH. TONIGHT...UPPER TROUGH AND DEEPER MOISTURE WILL SLIDE EAST AND OUT OF THE CWA...AND DO NOT SEE MUCH CHANCE FOR REMNANT LIGHT SPRINKLES/SHOWERS. MOSTLY CLOUDY SKIES ACROSS THE FAR SE ZONES WILL CLEAR BY MIDNIGHT...AS THE SFC HIGH RE-PLANTS ITSELF ACROSS THE CWA. SHOULD BE A NIGHT WITH PATCHY FOG...AND POSSIBLY MORE SO FOR THOSE AREAS THAT MAY MEASURE A FEW HUNDREDTHS FROM THE SHOWERS. WILL LET DAY CREW ASSESS FOG POTENTIAL...BUT WITH SFC TD'S HANGING IN THE UPPER 40S/LOW 50S THROUGH THE DAY...AND CLEARING OCCURRING OVERNIGHT...DO EXPECT AT LEAST PATCHY FOG...MAINLY OVER INLAND LAKES. LOWS SHOULD BE ABLE TO TUMBLE INTO THE MIDDLE 40S IN MANY INLAND AREAS. SATURDAY THROUGH SUNDAY...NOT MUCH GOING ON WITH SFC HIGH SLOWLY SLIDING THROUGH NRN MICHIGAN. HIGHS IN THE LOW TO MID 70S...LOW TEMPS IN THE LOW 40S (LOWEST AREAS) TO THE UPPER 40S. MAYBE SOME HIGH CLOUD TRAVERSING THE SKY...BUT PARTLY SUNNY AND PLEASANT FOR THE WEEKEND. SUNDAY ONWARD...NO MAJOR CHANGES...MODELS HOWEVER ARE STARTING TO DOWNPLAY THE FRONT ARRIVING SUNDAY AFTERNOON AND SUNDAY NIGHT...AND ARE RATHER PLAYING UP A POSSIBLE NEW WAVE RIDING THIS BOUNDARY MONDAY. HAVER NOT MADE TOO MANY CHANGES AND WILL LET DAY CREW ASSESS ANY INCREASED POPS FOR MONDAY. I DID LOWER THE CHANCE FOR THUNDER WITH THE FRONT SUNDAY AFTERNOON AND SUNDAY NIGHT AS INSTABILITY LOOKS WEAK. SMD && .APX...WATCHES/WARNINGS/ADVISORIES...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1030 AM EDT FRI SEP 16 2005 .SHORT TERM (THIS AFTERNOON)... GOOD SUBSIDENCE IN WAKE OF OPHELIA AND VERY DRY ABOVE H8. A WEAK TROUGH LIES W OF THE AREA THIS AFTERNOON SO NOT ENIRELY IMPOSSIBLE FOR AN ISOLATED SHOWER OR THUNDERSTORM. SHOULD ALSO SEE A LATE DAY RESULTANT DEVELOP. THEREFORE WILL NOT REMOVE MENTION OF A SHOWER OR THUNDERSTORM FOR THE AFTERNOON HOURS. TEMPS SHOULD REACH 90 OR HIGHER JUST ABOUT EVERYWHERE IN WESTERLY FLOW. EXCEPTION MAY BE BRUNSWICK COUNTY BEACHES WHERE A LATE DAY SW BREEZE MAY KEEP THEM JUST SHY OF 90 DEG. && .MARINE... NORTHWEST TO WEST WINDS OF 10 KT ACROSS THE WATERS THIS MORNING WITH SEAS AT THE NOAA BUOYS OF 3.3 FT. 06Z ETA AND 09Z RUC SHOWING WINDS BACKING BY LATE AFTERNOON TO THE SOUTHWEST. ONLY CHANGES PLANNED ON THE UPDATE ARE TO SHOW SOUTHWEST WINDS. && .AVIATION... OUTSIDE SOME 3 TO 5 MILE HAZE THIS MORNING...EXPECT TO SEE VFR CONDITIONS THROUGH THE FORECAST PERIOD. EXPECT W-NW WINDS OF 5 TO 10 KT THIS MORNING TO BECOME MORE W-SW DURING THE DAY...PERHAPS EVEN SOUTHERLY AT CRE AND MYR. && .ILM WATCHES/WARNINGS/ADVISORIES... NC...NONE. SC...NONE. MARINE...NONE. && $$ SHORT TERM...RJD AVIATION...RAN MARINE...HAWKINS nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 750 PM CDT FRI SEP 16 2005 .CURRENT OBSERVATIONAL OVERVIEW... 00Z SURFACE ANALYSIS DEPICTED LOW PRESSURE OVER CENTRAL SOUTH DAKOTA WITH ATTENDANT FRONTAL BOUNDARY FROM SOUTH CENTRAL NORTH DAKOTA INTO NORTHWEST MINNESOTA. LATEST RADAR MOSAIC/W/V IMAGERY SHOWED CONVECTION FIRING JUST TO THE NORTH OF BOUNDARY IN RESPONSE TO UPSTREAM VORTICITY MAXIMA OVER SOUTHWEST NORTH DAKOTA. .SHORT TERM... 23Z RUC MODEL HAD GOOD HANDLE ON PLACEMENT OF SURFACE AND UPPER LEVEL FEATURES. INCREASING LOW LEVEL JET LATER THIS EVENING AND OVERNIGHT STILL APPEARS TO BE MAIN MECHANISM TO SPAWN SCATTERED ELEVATED CONVECTION ALONG AND NORTH OF BOUNDARY. ATTM NO MAJOR CHANGES PLANNED TO CURRENT ZONES. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ BERG nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX 845 PM CDT FRI SEP 16 2005 .DISCUSSION... WEAK QUASI-STATIONARY FRONTAL BOUNDARY (EVIDENT IN SATELLITE IR LOOP AND GRK 0.5 REFLECTIVITY LOOP) BETWEEN CLL AND 11R EXTENDING EAST TO JUST SOUTH OF UTS AND FARTHER EAST TO NEAR CORRIGAN. RUC HAS THIS BOUNDARY ESSENTIALLY STAYING OVER SAME AREA OVERNIGHT WHILE BECOMING MORE DIFFUSE. 00Z SURROUNDING SOUNDINGS AND GOES SOUNDER INDICATE STILL MOIST AIR MASS OVER MUCH OF OUR CWFA NEAR 2.O INCHES. CONVECTIVE ACTIVITY OVER CWFA HAS ALREADY DISSIPATED. WE SHALL ADJUST 1ST PERIOD MAINLY FOR CENTRAL AND SOUTHERN WITH MENTION OF SLIGHT CHANCE SHRA/TSRA FOR REST OF TONIGHT. REST OF ZFPHGX ON TRACK. 37 && .PREVIOUS DISCUSSION... SCATTERED SHOWERS ALONG WITH ISOLATED THUNDERSTORMS CONTINUE ACROSS THE SOUTHEASTERN THREE-QUARTERS OF SOUTHEAST TEXAS. A WARM AND VERY HUMID AIR MASS REMAINS IN PLACE THROUGHOUT THE REGION AHEAD OF A WEAK COLD FRONT THAT REMAINS DRAPED ACROSS PARTS OF NORTHERN AND CENTRAL TEXAS. THE FRONT IS NOT EXPECTED TO MAKE MUCH SOUTHWARD PROGRESSION...BUT AN OUTFLOW BOUNDARY AHEAD OF THE SYNOPTIC FRONT HAS BEEN MOVING THROUGH OUR AREA AND HAS BEEN HELPING TO INITIATE THE PRECIPITATION TODAY. THIS ACTIVITY WILL BEGIN TO WANE LATER THIS EVENING AS THE SUN SETS. IT IS POSSIBLE A FEW SHOWERS COULD LINGER TOMORROW MORNING. FOR THE LONG TERM...IT LOOKS LIKE A RETURN TO SUMMER AS A STOUT MID LEVEL HIGH BUILDS IN ACROSS THE SOUTHERN HALF OF THE NATION. THE LATEST MODEL GUIDANCE CONTINUES ITS TREND OF STRENGTHENING THE RIDGE THROUGH ALMOST ALL OF NEXT WEEK. WE VERY WELL COULD SEE AFTERNOON TEMPERATURES APPROACHING 100 DEGREES...ESPECIALLY OVER THE NORTHERN PARTS OF THE AREA. MEANWHILE...IT LOOKS LIKE LITTLE CHANCE FOR RAIN AS SUBSIDENCE FROM THE RIDGE AND MID LEVEL WARM TEMPERATURES INHIBIT CONVECTIVE DEVELOPMENT. 46 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 1241 PM CDT FRI SEP 16 2005 .UPDATE... WENT AHEAD AND LOWERED TEMPS MAINLY ACROSS THE CONCHO VALLEY THIS AFTERNOON. ALSO BUMPED UP POPS FURTHER SOUTH NEAR THE I10 CORRIDOR WITH CUMULUS DEVELOPING ALONG THE FRONTAL BOUNDARY. .AVIATION... WEAK COLD FRONT HAS NEARLY STALLED FROM NEAR KBMQ TO NEAR OR JUST SOUTH OF I10 NEAR KJCT TO KSOA LATE THIS MORNING. NORTH OF THE FRONT...ISENTROPIC LIFTING ALONG WITH RESIDUAL LOW LEVEL MOISTURE RESULTED IN LIFR CIGS AT KSJT WITH MVFR CIGS FURTHER NORTH AT KABI THIS MORNING. LOW CLOUDS ARE SLOWLY LIFTING LATE THIS MORNING AND EXPECT TO SEE SOME BREAKS THIS AFTERNOON. WILL CONTINUE WITH MVFR FOR BOTH KABI AND KSJT THROUGH 20Z WITH CONDITIONS IMPROVING THEREAFTER. WILL MENTION THE CHANCE OF THUNDERSTORMS ALONG THE FRONTAL BOUNDARY AS A CUMULUS FIELD HAS BEGUN TO DEVELOP ALONG I10. WINDS SHOULD REMAIN IN THE 5 TO 10 KNOT RANGE THROUGH THE REMAINDER OF THE DAY WITH THE EXCEPTION OF AREAS NEAR THUNDERSTORMS. AS FOR TOMORROW MORNING...LOOKS LIKE LOW CEILINGS AND FOG MAY BE AN ISSUE AGAIN AT KSJT WITH THE RAINFALL FROM THE PREVIOUS DAYS AND A SIMILAR SETUP IN PLACE. && .PREV DISCUSSION... (ISSUED 1106 AM CDT FRI SEP 16 2005) UPDATE... BIGGEST PROBLEM FOR THIS AFTERNOON WILL BE CLOUD COVER AND MAX TEMPS. ADJUSTED THE TEMPS DOWN AS COOL FRONT AND CLOUD COVER WILL HOLD TEMPS DOWN. LATEST RUC SOUNDINGS SHOW SOME BREAKS IN THE OVERCAST BY LATE AFTERNOON. WEAK FRONTAL BOUNDARY HAS PUSHED SOUTH OF CWA. HOWEVER...A VERY LOW LEVEL FRONTAL INVERSION WILL BE SLOW TO BREAK. MAY HAVE TO LOWER MAX TEMPS ANOTHER CATEGORY. STAY TUNED. PREV DISCUSSION... (ISSUED 617 AM CDT FRI SEP 16 2005) AVIATION... COLD FRONT IS NOW NEARLY STATIONARY FROM KJCT TO JUST SOUTH OF KSOA AND KP07. IN THE WAKE OF THE FRONT WIDE SPREAD MVFR CIGS WITH AREAS OF IFR GIGS. WINDS GENERALLY FROM THE NORTHEAST 5 TO 10 KNOTS. LINE OF BROKEN SHOWERS...POSSIBLY A THUNDERSTORM FROM ABOUT 12 SOUTH OF KSWW TO 4 MILES SOUTH OF KABI TO NEAR KSEP. AS FOR THE TWO TERMINALS WITH THIS FORECAST...WILL NEED TO START OFF MENTIONING SOME SHRA IN THE KABI TAF AS IT IS ALREADY IN THE VICINITY AND WILL CONTINUE THE SHRA THROUGH ABOUT 16Z AS FRONTAL ZONE BEGINS TO WASH OUT. WILL CONTINUE THE MVFR CIGS THROUGH ABOUT 18Z THEN CONDITIONS SHOULD BEGIN TO IMPROVE AS MID SEPTEMBER SUN SHOULD ERODE THE CLOUDS. WINDS TO STAY 020 TO 050 LESS THAN 10 KNTS. THROUGH MUCH OF THE DAY. HAVE BEEN IN LIMBO AS TO WHETHER TO MENTION SOME SHRA AT THE KSJT TERMINAL...BUT GIVEN THE LIMITED TIME TO DEVELOP AND SEE NOTHING IN THE VCNTY AT THIS TIME WILL GO AHEAD AND LEAVE OUT AT THIS POINT IF ANYTHING WERE TO DEVELOP...BEST TIME WOULD BE BETWEEN 12Z-14Z. IFR CIGS AT KSJT ARE ANTICIPATED TO INCREASE TO MVFR BY 16Z AND THEN CIG SHOULD ALSO BEGIN TO BREAK BY 19Z AS FRONTAL SURFACE BEGINS TO ERODE. WINDS PRETTY MUCH 040-060 AROUND 10 KNTS OR LESS. 27/BRAZZELL PREV DISCUSSION... (ISSUED 311 AM CDT FRI SEP 16 2005) SHORT TERM... REMNANTS OF COLD FRONT EXTENDED FROM SOUTH OF OZONA...JUNCTION TO NEAR WACO EARLY THIS MORNING...WITH NORTHEAST WINDS OF 5 TO 10 MPH IN WEST CENTRAL TEXAS. SURFACE DEW POINTS WERE STILL PRETTY HIGH IN WC TEXAS WITH UPPER 60S TO LOWER 70S...THOUGH SOME DRIER AIR WITH DEW POINTS IN LOWER 60 WAS MOVING INTO HASKELL AND THROCKMORTON COUNTIES. SOME ISOLATED THUNDERSTORMS EXTENDING FROM NEAR ABILENE TO THE FT WORTH/DALLAS METROPLEX. WHILE...KSJT RADAR VAD SHOWED ONLY ONE GATE OF SOUTH WINDS OF 15 KTS AT 5000 MSL...LOW AND MID LEVEL CLOUDS CONTINUE TO DEVELOP OVER THE REGION...INDICATING MID LEVEL MOISTURE CONVERGENCE. OTHERWISE...WATER VAPOR LOOP INDICATED MID/UPPER RIDGING DEVELOPING AND MOVING IN FROM THE SOUTHWEST UNITED STATES. QUESTION OF POPS FOR TODAY...TO PUT IN OR NOT. NEGATIVES ARE THE INCREASING UPPER RIDGING AND DRIER AIR WORKING IN FROM THE NORTH. POSITIVES ARE...WE ARE SLIGHTLY UNSTABLE...ESPECIALLY OVER AREAS EAST AND SOUTH OF THE CONCHO VALLEY TODAY. THE ETA MODEL IS A BIT MORE AGRESSIVE AS POPS ARE CONCERNED BUT GFS DOES DEPICT SOME PRECIP IN THE REGION (MAINLY MORNING). WE ALSO HAVE SOME LEFT OVER THUNDERSTORM OUTFLOW BOUNDARIES...AND APPARENT MID LEVEL MOISTURE CONVERGENCE OVER THE REGION. WILL GIVE A 20 PERCENT FROM I-20 SOUTHWARD TODAY. WITH NO UPPER LEVEL SHORTWAVES AND WEAKER INSTABILITY...LEFT OUT MENTION OF TSTMS CHANCES TONIGHT. LONG TERM... UPPER RIDGING CONTINUE TO DEVELOP AND GRADUALLY INCREASE IN STRENGTH THROUGH THE MIDDLE OF NEXT WEEK. LOOKS DRY AND WARM. SJT WATCHES/WARNINGS/ADVISORIES... NONE. $$ && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 26/19/05 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 1106 AM CDT FRI SEP 16 2005 .UPDATE... BIGGEST PROBLEM FOR THIS AFTERNOON WILL BE CLOUD COVER AND MAX TEMPS. ADJUSTED THE TEMPS DOWN AS COOL FRONT AND CLOUD COVER WILL HOLD TEMPS DOWN. LATEST RUC SOUNDINGS SHOW SOME BREAKS IN THE OVERCAST BY LATE AFTERNOON. WEAK FRONTAL BOUNDARY HAS PUSHED SOUTH OF CWA. HOWEVER...A VERY LOW LEVEL FRONTAL INVERSION WILL BE SLOW TO BREAK. MAY HAVE TO LOWER MAX TEMPS ANOTHER CATEGORY. STAY TUNED. && .PREV DISCUSSION... (ISSUED 617 AM CDT FRI SEP 16 2005) AVIATION... COLD FRONT IS NOW NEARLY STATIONARY FROM KJCT TO JUST SOUTH OF KSOA AND KP07. IN THE WAKE OF THE FRONT WIDE SPREAD MVFR CIGS WITH AREAS OF IFR GIGS. WINDS GENERALLY FROM THE NORTHEAST 5 TO 10 KNOTS. LINE OF BROKEN SHOWERS...POSSIBLY A THUNDERSTORM FROM ABOUT 12 SOUTH OF KSWW TO 4 MILES SOUTH OF KABI TO NEAR KSEP. AS FOR THE TWO TERMINALS WITH THIS FORECAST...WILL NEED TO START OFF MENTIONING SOME SHRA IN THE KABI TAF AS IT IS ALREADY IN THE VICINITY AND WILL CONTINUE THE SHRA THROUGH ABOUT 16Z AS FRONTAL ZONE BEGINS TO WASH OUT. WILL CONTINUE THE MVFR CIGS THROUGH ABOUT 18Z THEN CONDITIONS SHOULD BEGIN TO IMPROVE AS MID SEPTEMBER SUN SHOULD ERODE THE CLOUDS. WINDS TO STAY 020 TO 050 LESS THAN 10 KNTS. THROUGH MUCH OF THE DAY. HAVE BEEN IN LIMBO AS TO WHETHER TO MENTION SOME SHRA AT THE KSJT TERMINAL...BUT GIVEN THE LIMITED TIME TO DEVELOP AND SEE NOTHING IN THE VCNTY AT THIS TIME WILL GO AHEAD AND LEAVE OUT AT THIS POINT IF ANYTHING WERE TO DEVELOP...BEST TIME WOULD BE BETWEEN 12Z-14Z. IFR CIGS AT KSJT ARE ANTICIPATED TO INCREASE TO MVFR BY 16Z AND THEN CIG SHOULD ALSO BEGIN TO BREAK BY 19Z AS FRONTAL SURFACE BEGINS TO ERODE. WINDS PRETTY MUCH 040-060 AROUND 10 KNTS OR LESS. 27/BRAZZELL PREV DISCUSSION... (ISSUED 311 AM CDT FRI SEP 16 2005) SHORT TERM... REMNANTS OF COLD FRONT EXTENDED FROM SOUTH OF OZONA...JUNCTION TO NEAR WACO EARLY THIS MORNING...WITH NORTHEAST WINDS OF 5 TO 10 MPH IN WEST CENTRAL TEXAS. SURFACE DEW POINTS WERE STILL PRETTY HIGH IN WC TEXAS WITH UPPER 60S TO LOWER 70S...THOUGH SOME DRIER AIR WITH DEW POINTS IN LOWER 60 WAS MOVING INTO HASKELL AND THROCKMORTON COUNTIES. SOME ISOLATED THUNDERSTORMS EXTENDING FROM NEAR ABILENE TO THE FT WORTH/DALLAS METROPLEX. WHILE...KSJT RADAR VAD SHOWED ONLY ONE GATE OF SOUTH WINDS OF 15 KTS AT 5000 MSL...LOW AND MID LEVEL CLOUDS CONTINUE TO DEVELOP OVER THE REGION...INDICATING MID LEVEL MOISTURE CONVERGENCE. OTHERWISE...WATER VAPOR LOOP INDICATED MID/UPPER RIDGING DEVELOPING AND MOVING IN FROM THE SOUTHWEST UNITED STATES. QUESTION OF POPS FOR TODAY...TO PUT IN OR NOT. NEGATIVES ARE THE INCREASING UPPER RIDGING AND DRIER AIR WORKING IN FROM THE NORTH. POSITIVES ARE...WE ARE SLIGHTLY UNSTABLE...ESPECIALLY OVER AREAS EAST AND SOUTH OF THE CONCHO VALLEY TODAY. THE ETA MODEL IS A BIT MORE AGRESSIVE AS POPS ARE CONCERNED BUT GFS DOES DEPICT SOME PRECIP IN THE REGION (MAINLY MORNING). WE ALSO HAVE SOME LEFT OVER THUNDERSTORM OUTFLOW BOUNDARIES...AND APPARENT MID LEVEL MOISTURE CONVERGENCE OVER THE REGION. WILL GIVE A 20 PERCENT FROM I-20 SOUTHWARD TODAY. WITH NO UPPER LEVEL SHORTWAVES AND WEAKER INSTABILITY...LEFT OUT MENTION OF TSTMS CHANCES TONIGHT. LONG TERM... UPPER RIDGING CONTINUE TO DEVELOP AND GRADUALLY INCREASE IN STRENGTH THROUGH THE MIDDLE OF NEXT WEEK. LOOKS DRY AND WARM. && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 26/19 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHEYENNE WY 208 PM MDT FRI SEP 16 2005 .SHORT TERM...TONIGHT...THE 18Z NAM AND RUC CONTINUE THE THEME OF A SHORTWAVE FEATURE RIDING A 100 KNOT JET INTO THE FORECAST AREA FROM UTAH. LOW-LEVEL MOISTURE IS NON-EXISTENT WITH DEW POINTS IN THE TEENS AND 20S BLANKETING MOST OF THE REGION. SOUTHERLY WINDS WILL ADVECT SOME MOISTURE INTO THE PANHANDLE OVER THE COMING HOURS...BUT OVERALL EXPECTING MAINLY WIND-PRODUCING STORMS GENERALLY NORTH OF A WHEATLAND-ALLIANCE LINE EARLY THIS EVENING. A LEE SIDE TROUGH WILL KEEP WINDS UP EAST OF THE LARAMIE RANGE...THUS AN UNSEASONABLY MILD NIGHT IS IN STORE FOR THOSE LOCATIONS...EVEN UNDER MOSTLY CLEAR SKIES. POMEROY .LONG TERM...SAT THRU FRI. COLD FRONTAL BOUNDARY SAGS SWRD ACROSS THE ZONES SAT NIGHT/SUN THUS POPS ORIENTED ACCORDINGLY ALONG FRONT. WILL SIDE CLOSER TO DRIER GFS SOLUTION FOR MON WITH RIDGING PREVAILING. RIDGING PREVAILS AGAIN TUE. SLIM CHANCE OF LATE DAY CONVECTION ACROSS OUR SWRN ZONES...WHICH IS ALREADY COVERED IN OUR GRIDS. RIDGE BREAKS DOWN SOMEWHAT ON WED...THUS BETTER TSTM CHANCES THEN. THU LOOKS DRY AGAIN AS LOW/MID LEVEL MOISTURE DECREASES. SWLY FLOW ALOFT KEEPS US DRY ON FRI...ESPECIALLY WITH LIMITED LOW/MID LEVEL MOISTURE. RUBIN && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ wy AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 408 AM MDT SAT SEP 17 2005 .SHORT TERM... (TODAY AND TONIGHT) SHORT TERM CONCERNS REMAIN WINDS...TEMPERATURES AND FIRE DANGER. CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING MODERATE SOUTHWEST FLOW ACROSS THE STATE WITH MINOR SHORT WAVE AND ASSOCIATED 90+KT JET CORE MOVING ACROSS THE STATE ATTM. WATER VAPOR IMAGERY ALSO INDICATING BROAD UPPER CIRCULATION ACROSS THE PAC NW WITH ASSOCIATED JET ROUNDING THE BASE OF THE LOW ACROSS THE NORTHERN GREAT BASIN ATTM. AT THE SFC...LEE TROUGH ACROSS EASTERN COLORADO KEEPING BRISK SOUTHERLY WINDS AND TEMPS UP ACROSS THE FAR EASTERN PLAINS. PASSING JET CORE ALSO KEEPING BREEZY AND DRY CONDITIONS ACROSS THE HIGHER ELEVATIONS WITH DEW PTS IN THE TEENS AND 20S ATTM. TODAY AND TONIGHT...BROAD UPPER LOW MOVES ACROSS THE NORTHERN ROCKIES...KEEPING MODERATE AND DRY SW FLOW ACROSS THE REGION. MODEL SOUNDINGS INDICATING DEEP MIXING POTENTIAL TO AROUND H5 ONCE AGAIN TODAY...AND WITH INCREASING LAPSE RATES TO BETWEEN 8-9C/KM ALONG WITH SOLAR HEATING...SHOULD SEE GUSTY SW WINDS OF 30-40 MPH ACROSS THE HIGHER TERRAIN AND 20-30 MPH ACROSS THE ADJACENT PLAINS EARLY THIS AFTERNOON AND EVENING. MODELS INDICATING SLIGHT WARMING ALOFT AND SHOULD SEE TEMPERATURES AT OR SLIGHTLY ABOVE YESTERDAYS READINGS WITH 80S TO LOWER 90S ACROSS THE PLAINS AND MID 50S TO MID 70S ACROSS THE HIGHER TERRAIN. WITH WARM TEMPS AND CURRENT LOW DEW PTS...MINIMUM RHS EXPECTED TO BE AT OR BELOW 15 PERCENT...AND WITH CRITICAL FUELS PER RMACC ACROSS THE MOUNTAINS AND HIGH MT VALLEYS... WILL ISSUE A RED FLAG WARNING FOR ZONES 220>225 FROM NOON TO 9 PM. WINDS LOOK TO DECOUPLE...SAVE THE HIGHER MOUNTAIN TOPS...ONCE AGAIN THIS EVENING WITH LOSS OF HEATING...AND ONLY MADE MINOR TWEAKS TO REST OF TONIGHTS FORECAST...WITH MAINLY CLEAR SKIES AND NO PCPN EXPECTED. .LONG TERM... (SUNDAY THROUGH FRIDAY) DRY AND BREEZY SW FLOW WL BE SEEN OVR THE AREA ON SUN. A WEAK COLD FRONT MAY PUSH SOUTH INTO THE SERN PLAINS IN THE AFTERNOON HOURS ACCORDING TO THE GFS...WHILE THE NAM HAS THE FRONT HANGING UP NORTH OF THE AREA. THIS EXPLAINS THE WARMER MAX TEMPS ON THE MET GUIDANCE AS COMPARED TO THE MAV NUMBERS. OUR MAX T GRID HAS VALUES SOMEWHERE IN BETWEEN THE MET AND MAV WHICH SEEMS TO BLEND WELL WITH SURROUNDING AREAS. THE NAM THEN BACKS THIS FRONT INTO THE SERN PLAINS LATE SUN NIGHT/EARLY MON MORNING...AND BRINGS AN INCREASE IN LOW LVL MSTR TO SOME OF THE FAR SERN AREAS. IN THE WAKE OF THIS FRONT...TEMPS SHOULD BE A LITTLE COOLER MON OVR PORTIONS OF THE SE PLAINS. THE 06Z RUN OF THE NAM ALSO SHOWS ENOUGH MSTR BY LATE AFTERNOON THAT ALONG WITH THE HEATING AND LOW LEVEL UPSLOPE...WE COULD SEE SOME TSTMS OVR PORTIONS OF THE ERN PLAINS AND MTS...AND WITH SOME MSTR ALSO WORKING ITS WAY UP OVR SWRN CO...THIS AREA COULD ALSO SEE SOME PCPN. AN UPR RIDGE WL BE CENTERED OVR NORTH CENTRAL TX TUE AND THEN IT SHIFTS A LITTLE EWRD FOR WED. THE FLOW OF MSTR AROUND THE BACK SIDE OF THE RIDGE INTO WRN CO IS EXPECTED TO CONTINUE BOTH DAYS...SO WL KEEP SOME POPS IN THE WRN AREAS. AT THE SAME TIME AN UPR TROF WL MOVE INTO THE GREAT BASIN BY EARLY WED. TEMPS WARM UP AGAIN FOR TUE AND WED OVR THE SE PLAINS...TO GENERALLY ABOVE NORMAL...WITH SOME LOWER 90S EXPECTED OVR THE SE PLAINS. SOME COOLING WL PROBABLY OCCUR WED OVR WRN AREAS AS THE UPR TROF APPROACHES PUSHING SOME COOLER AIR AND MORE CLOUDS INTO THE AREA. WED NIGHT/THU THAT UPR TROF MOVES ACRS CO BRINGING SOME COOLING. && .PUB WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING FROM NOON SATURDAY TO 9 PM SATURDAY FOR FIRE ZONES 220>225. && $$ co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1111 AM EDT SAT SEP 17 2005 .UPDATE... WEAKLY CYCLONIC LOW-LEVEL FLOW HAS BEEN MORE PERSISTENT ACROSS SOUTHEAST MICHIGAN...WITH SURFACE HIGH FROM LAKE MICHIGAN TO NORTHERN LAKE HURON SLOWER TO BUILD DOWN ACROSS THE STATE. LINGERING LOW-LEVEL MOISTURE AND WEAK LIFT HAD LED TO A PERSISTENT LOW CLOUD DECK. ISOLATED ECHOES ARE STILL APPARENT DEVELOPING OFF THE SOUTHERN END OF LAKE HURON. 14Z-15Z ACARS SOUNDINGS NEAR DTW SHOW A SOLID NEARLY SATURATED LAYER FROM THE SURFACE THROUGH 800MB. 12Z RUC ALSO SHOWS MOISTURE HOLDING ON FOR LONGER...WITH A CONTINUED NORTHEASTERLY CYCLONIC GRADIENT THROUGH MID AFTERNOON. WILL UPDATE TO CARRY ISOLATED LIGHT SHOWERS FOR A FEW MORE HOURS INTO THE EARLY AFTERNOON...AND ALSO HOLD ONTO CLOUDS LONGER THROUGH THE DAY. FAR NORTHWEST CWA CLEARED OUT BY SUNRISE...BUT THE BACK EDGE OF THE CLOUDS HAS MADE LITTLE SOUTHEASTWARD PROGRESS SINCE THEN. IN FACT... LATEST VIS SATELLITE SHOWS SOME CU BEGINNING TO FILL IN ALONG THE BACK EDGE. EXPECT CEILING HEIGHTS TO CONTINUE TO RISE AS THEY HAVE DONE THROUGH THE MORNING...BUT CLOUDS WILL STICK AROUND LONGER THROUGH THE AFTERNOON. WITH LIMITED INSOLATION...WILL ALSO NEED TO TRIM HIGHS ACROSS THE SOUTHEAST CWA BACK A DEGREE OR TWO. && .AVIATION...700 AM EDT SAT SEP 17 2005 LOW CEILINGS AND PATCHES OF FOG/DRIZZLE WILL AFFECT DTW/DET AND VICINITY FOR SEVERAL HOURS THIS MORNING. WILL CONTINUE WITH CIGS IN/AROUND 1000 FEET AND VSBYS TEMPO-ED DOWN TO 4SM OR SO WITH A FEW PATCHES OF DRIZZLE FUNNELING DOWN NORTHEAST FLOW FROM LAKE HURON. HIGH PRESSURE...AND MUCH DRIER AIR...IS WORKING SOUTH INTO THE AREA EARLY THIS MORNING...WITH A DISTINCT CLEARING OVER SAGINAW BAY IN THE 11U-3.9U IMAGERY DURING THE PAST FEW HOURS. WILL BREAK CLOUDS OUT BY MIDDAY AT THE LATEST...HOLDING ON THE LONGEST IN DTW/DET. MBS WILL CLEAR OUT IN AN HOUR OR TWO...WITH DTW/DET WAITING UNTIL 18-19Z TIMEFRAME (ALBEIT WITH HIGHER CEILINGS AFTER A FEW HOURS THIS MORNING). CLEAR SKIES BY THIS EVENING...WITH PERHAPS JUST A TOUCH OF LIGHT FOG TONIGHT WITH HIGH PRESSURE BUILDING SOUTH THROUGH THE AREA. && .SHORT TERM...SATURDAY AND SATURDAY NIGHT...ISSUED AT 338 AM EDT STRATUS WILL BE A BIT SLOW TO ERODE THIS MORNING...BUT DO EXPECT A FAIR AMOUNT OF SUNSHINE ACROSS SOUTHEAST MICHIGAN BY THIS AFTERNOON. IN FACT...WOULD EXPECT THE SUN TO BREAK OUT IN THE SAGINAW AND GENESEE VALLEYS BY MID MORNING. THIS WILL LEAD TO A MILD DAY WITH HIGHS BACK INTO THE 70S. WILL PLAY THE FORECAST SOMEWHAT CONSERVATIVELY GIVEN THE MORNING CLOUD COVER. BASICALLY EXPECT THE NORTHWEST CWA TO APPROACH GUIDANCE VALUES IN THE MID/UPPER 70S WITH AREAS FURTHER SOUTHEAST MORE LIKELY TO STAY BELOW GUIDANCE AND HOLD IN THE LOWER 70S...WHERE CLOUD COVER WILL TAKE A FEW EXTRA HOURS TO BREAK UP. COOL...NORTHEAST FLOW WILL NOT HELP IN A QUICK RECOVERY THIS AFTERNOON. BASICALLY CLEAR SKIES BY EVENING AND OVERNIGHT. WITH HIGH PRESSURE SETTLING THROUGH THE REGION...WINDS WILL BE LIGHT. WILL MAINTAIN A RELATIVELY COOL FORECAST...IN/AROUND 50 IN MOST LOCATIONS. INTERIOR METRO DETROIT AND LOCATIONS IMMEDIATELY ADJACENT TO THE RELATIVE WARMTH OF THE GREAT LAKES WILL BE THE EXCEPTIONS...HOLDING MORE IN THE MID 50S. && .LONG TERM...SUNDAY THROUGH FRIDAY...ISSUED AT 338 AM EDT A VERY CHALLENGING FORECAST AS WE WILL FOLLOW THE GFS/ECMWF/CANADIAN ...WHICH LEADS TOWARD MORE AMPLIFICATION AND THE CHANCE FOR SEVERE WEATHER ON MONDAY. STARTING WITH SUNDAY...WEAKENING SHORT WAVE TROF APPROACHING AND SOME Q-VECTOR CONVERGENCE MOVES ACROSS THE STATE YET LOWER LEVELS ARE QUITE DRY WITH AOA 1020MB SURFACE HIGH IN PLACE. MAIN SURFACE CONVERGENCE IS ALONG THE COLD FRONT THAT WILL LIKELY REMAIN ACROSS THE STRAIGHTS AS PACIFIC ENERGY (SEEN IN THE H2O VAPOR LOOP THIS MORNING ACROSS THE PACIFIC NORTHWEST) EJECTS INTO THE CENTRAL PLAINS AND MID LEVEL FLOW SHOULD BECOME PARALLEL TO THE SURFACE TO IMPEDE FORWARD PROPAGATION. SO A DRY AND WARMER DAY WITH TEMPERATURES COMING CLOSE TO THE 80F DEGREE MARK. UPSTREAM ACTIVITY WILL BE THE KEY TO OUR SEVERE WEATHER POTENTIAL ON MONDAY. AFTER CLOSE COLLABORATION WITH SPC THIS MORNING...THE APPROACH OF PACIFIC SYSTEM AND NOCTURNAL LOW LEVEL JET FORCING WILL LIKELY RESULT IN ONE OR MORE MCS/S ACROSS THE MISSISSIPPI RIVER VALLEY. HOWEVER...WE ARE EXPECTING AN EXTENSIVE SUBTROPICAL RIDGE TO DEVELOP ACROSS THE SOUTHERN CONUS WHICH IN TURN WILL TIGHTEN THE THERMAL FIELDS AND MIGHT DAMPEN THE WAVE SOMEWHAT AS IT APPROACHES THE STATE MONDAY. THIS SETS UP A PROBLEM FOR THE SOUTHERN HALF OF THE CWA AS A MODEL BLEND SUGGESTS A LITTLE SLOWER TIMING AND IF WE RECEIVE ADDITIONAL INSOLATION ALONG WITH LOW LEVEL MOISTURE ADVANCING NORTHWARD...PLENTY OF SHEAR EXPECTED FOR ORGANIZED CONVECTION ESPECIALLY IF WARM FRONTAL/DEWPOINT BOUNDARY BECOMES QUASI-STATIONARY ACROSS THE CWA. STILL PLENTY OF TIME TO MONITOR AND WE INTEND TO HIGHLIGHT THIS WITHIN THE HWO (HAZARDOUS WEATHER OUTLOOK) THIS MORNING. WE WILL RAISE TEMPERATURES A FEW DEGREES FROM CURRENT FORECAST WITH THE ANTICIPATION OF ADDITIONAL SUNSHINE AND WARMING COLUMN. WE WILL ALSO RETAIN THE CHANCE FOR CONVECTION UNTIL TIMING BECOMES MORE APPARENT (SEE SWODY3 FOR ADDITIONAL DETAILS). FRONTAL BOUNDARY TIMING SEEMS TO CLEAR THE CWA MONDAY NIGHT YET THE CANADIAN IS THE SLOWEST WITH THE GFS THE FASTEST. SO THE UKMET IS SOMEWHAT IN THE MIDDLE AND WE WILL KEEP THE CHANCE FOR ADDITIONAL CONVECTION OVERNIGHT AND BRING BACK THE CHANCES FOR LIGHT SHOWERS ON TUESDAY MORNING. THEN IMPRESSIVE SUBSIDENCE UNFOLDS WITH INCREASING AMOUNTS OF SUNSHINE AND 850MB TEMPS SUPPORT TEMPERATURES INTO THE MIDDLE 70S. THEN IT LOOKS FAIRLY QUIET (OUTSIDE OF TROPICAL ACTIVITY) THROUGH MID WEEK UNTIL ADDITIONAL PACIFIC ENERGY COMES ASHORE AS IT SEEMS WE GO THROUGH A REPEAT PERFORMANCE BY THURSDAY AND FRIDAY. THERE IS ENOUGH EVIDENCE TO BRING IN THE CHANCE FOR CONVECTION AT THIS TIME. THE ECMWF IS THE MOST EMPHATIC WITH ITS 850MB WARM THERMAL ADVECTION ON THURSDAY WITH THE DGEX SOMEWHAT IN LINE AND THE CANADIAN MORE DIFFUSE. EITHER WAY...THIS CHANGE IS IN AGREEMENT WITH COLLABORATION WITHIN NEIGHBORING OFFICES. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ UPDATE.......BRAVENDER AVIATION.....DG SHORT TERM...DG LONG TERM....BGM HTTP://WEATHER.GOV/DETROIT mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 945 AM CDT SAT SEP 17 2005 .DISCUSSION...TODAY AND TONIGHT TWO SEPARATE AREAS OF PCPN EVIDENT ON LOCAL 88D MOSAIC THAT EITHER ARE CURRENTLY OR WILL BE AFFECTING THE FA THIS MRNG AND EARLY AFTN. THE FIRST AREA STRETCHES FM NR GRANITE FALLS NEWRD TO NR DULUTH...WHILE THE SECOND IS CURRENTLY CONFINED TO THE SRN AND CNTRL PORTIONS OF THE FSD CWA. THE FORMER IS ASSOC WITH AN AREA OF FRONTOGENESIS ALNG THE CDFNT FM CNTRL SD TO NR KINL /EVIDENT IN THE H8 AND H7 RUC ANALYSES/...A PRONOUNCED AREA OF LOW CONDENSATION PRESSURE DEFICITS ON THE 310K ISENTROPIC SFC...AND THE ORIENTATION OF A 45-50 KT LLJ. THIS ACTIVITY SHUD MOVE EWRD AND WEAKEN SLIGHTLY...AS THE CONDENSATION PRESSURE DEFICITS INCR AND THE LLJ PUSHES N OF THE FA. HOWEVER...HAVE MADE SIGNIFICANT CHGS TO THE POP/WX FCST FOR TODAY...MAINLY TO RAISE POPS THIS MRNG INTO THE LIKELY CATEGORY AND ALSO TO PUSH POPS FARTHER EWRD THAN THE INHERITED FCST. THE SRN SHRA/TSRA IS ASSOCIATED WITH A S/W ALNG THE NE/SD BORDER PER W/V IMAGERY. BOTH THE 06Z NAM AND THE RUC FCSTS SHOW THIS AREA WEAKENING AS IT MOVES NWRD...AND THEREFORE...HAVE KEPT THE LOWEST POPS ACRS THE SRN PART OF THE FA AFT THIS MRNG'S PD. AFT THIS MRNG AND INTO THE MID AFTN PD...ANOTHER S/W TROF WL MOVE ACRS THE NRN PART OF THE FA AHD OF THE SFC BNDRY...WHICH WL SERVE TO INCR POPS ONCE AGAIN LATE THIS AFTN AND INTO THE EVENING HRS. HAVE ALSO INCR POPS INTO THE HIGH CHC CATEGORY ACRS THE NRN THIRD TO HALF OF THE FA. WL CONTINUE TO MONITOR THIS SCENARIO AS NEW DATA COME IN TO DETERMINE WHETHER HIGHER POPS WILL BE REQUIRED. ADJUSTED MAX TEMPS UP A COUPLE OF DEGS PER THE 12Z KMPX SOUNDING... AND ALSO LOWERED DEW PTS IN THE WEST THRU THE OVRNGT PD...AS DEW PTS ARE INCR AS QUICKLY AS FCST. AT 14Z...ONE MUST GO AS FAR S AS OK/AR TO SEE A WIDE AREA OF UPPER 50S DEW PTS...SO FELT CONFIDENT IN KNOCKING DOWN DEW PTS IN THE MID 50S ACRS THE WRN PART OF THE FA THRU AT LEAST TNGT. UPDATED PRODUCTS WL BE AVBL SHORTLY. KAT && .PREV DISCUSSION...(ISSUED 415 AM CDT SAT SEP 17 2005) TROUGH OF LOW PRESSURE EVIDENT FROM EASTERN COLORADO NORTHEAST INTO NORTHWEST MINNESOTA. REGIONAL RADAR DISPLAYS SHOW A CLUSTER OF SHOWERS AND THUNDERSTORMS PUSHING INTO OUR WESTERN COUNTIES IN THE SOUTHERLY FLOW IN ADVANCE OF THE SURFACE TROUGH. FORCING FOR THIS ACTIVITY WOULD APPEAR TO COME FROM LEFT FRONT QUAD INDUCED LIFT TIED TO SPEED MAX INITIALIZED ACROSS COLORADO INTO WESTERN IOWA ON INITIAL ANALYSIS OF 06Z NAM (40 KM) RUN. VERTICAL CROSS SECTIONS FROM SOUTHWEST TO NORTHEAST THROUGH OUR CWA INDICATE A FAIR AMOUNT OF DIFFICULTY FOR ACTIVITY OVER SOUTHWEST MINNESOTA TO MAKE IT INTO EAST CENTRAL MINNESOTA UNTIL THIS AFTERNOON AT THE EARLIEST. ALTHOUGH THERE CONTINUE TO BE CONSIDERABLE DIFFERENCES IN GFS AND NAM SOLUTIONS OVER THE LAST 24 HOURS...ONE CONSTANT APPEARS TO BE A FAIRLY STRONG CHANCE OF PRECIPITATION SUNDAY NIGHT AND THIS IS WHERE WE BEEFED UP POPS AND QPF. CROSS SECTIONAL ANALYSIS (RWF-MSP-RPD) FOR BOTH THE 00Z AND 06Z (40KM NAM) SHOW A SURGE IN LIFT OVER CWA IN THE 06Z MON TIME FRAME WITH 20 MICROBAR/SEC LIFT TOGETHER WITH CONVECTIVE INSTABILITY THROUGH 850-400 MB LAYER AND A VERTICAL AGEOSTROPHIC CIRCULATION FROM THE 70H LEVEL THROUGH 200 MB...ALL OF WHICH SUGGESTS A STRONG ROUND OF ELEVATED CONVECTION SUNDAY NIGHT. BOTH THE GFS AND NAM RUNS DO SHOW A COUPLED JET STRUCTURE ACROSS THE MPX CWA BY 06Z MONDAY WHICH WOULD GO A LONG WAY IN EXPLAINING ALL THE VIGOROUS LIFT THE MODELS HAVE PLANNED FOR US. LONGER TERM...TUESDAY THROUGH SATURDAY FLOW ALOFT IN LATER PERIODS BECOMING MORE ZONAL AGAIN. TIMING OF SHORT WAVES EMBEDDED WITHIN FLOW WILL BE DIFFICULT. 00Z 9/16 ENSEMBLES INDICATED BEST SHOT OF RAIN COMING IN A COUPLE OF PERIODS...MAINLY WED/WED NIGHT AS FRONT MOVES INTO THE REGION AND THEN AGAIN LATER FRIDAY AND FRIDAY NIGHT. THIS MATCHED WELL WITH TIMING OF WEATHER SYSTEMS ON THE 00Z 9/17 GFS AS WELL. ONLY MINOR CHANGES TO CURRENT FORECAST NEEDED. OVERALL...LOOKS LIKE THERE WILL BE A WARM PERIOD AHEAD OF FRONT WED THEN TRENDING COOLER...CLOSE TO OR SLIGHTLY BELOW NORMAL TOWARDS NEXT WEEKEND...AS MORE SIGNIFICANT TROUGH FORECAST TO MOVE THROUGH FRIDAY NIGHT. .MPX WATCHES/WARNINGS/ADVISORIES... .MN...NONE. .WI...NONE. && $$ mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BILLINGS MT 931 AM MDT SAT SEP 17 2005 .SHORT TERM...VALID FOR TDY AND SUN... UPDATE FOR ZONES AND STATE FORECAST THIS MORNING. UPPER LOW OVER WESTERN OREGON THIS MORNING. THIS LOW WILL DRIFT SLOWLY SOUTH TODAY WITH CHUNK OF ENERGY ROTATING AROUND THE BASE OF UPPER TROUGH INTO SOUTHWESTERN MONTANA. JET ENERGY CURRENTLY PUSHING INTO THE WESTERN ZONES THIS MORNING BRINGING STRONG DIVERGENCE ALOFT. HAVE INCREASED POPS TO CATEGORICAL OVER THE WEST TODAY WITH ON GOING PRECIP. LOW LEVELS HAVE MOISTEN UP ACROSS THE CENTRAL AND NORTHEAST ZONES. THIS HAS BROUGHT CLOUDY CONDITIONS TO THESE AREAS. FOG HAS DEVELOPED OVER THE BAKER AREA AND HAVE ADDED PATCHY FOG THROUGH 18Z TODAY. TEMPERATURES A TOUGH CALL TODAY AND HAVE LOWERED THEM TO REFLECT CURRENT TREND OF INCREASING LOW LEVEL MOISTURE AND UPSLOPE FLOW. RUC BRINGING DRY AIR OUT OF NE WY THIS AFTERNOON AND DID NOT ADJUST TEMPS FOR THIS AREA. LOW LEVELS WILL BE STABLE TODAY AND HAVE REMOVED MENTION OF THUNDERSTORMS OVER THE WEST AND CENTRAL ZONES. WILL KEEP THUNDERSTORMS WORKING OVER THE FAR SOUTHEAST AS SOME HEATING EXPECTED TODAY ALONG WITH SOME MIXING. 12Z NAM COMING IN AND SHOWING PRECIP CONTINUING OVER SOUTH CENTRAL AND SOUTHEAST MONTANA TONIGHT. WILL WAIT FOR THE GFS RUN BUT LIKELY POPS MAY BE NEEDED. NAM SHOWING 700MB LOW MOVING INTO NORTH DAKOTA BRINGING WRAP AROUND PRECIP TO SOUTHERN MONTANA. RICHMOND .LONG TERM...VALID FOR MON...TUE...WED...THU...FRI... MODELS IN GOOD AGREEMENT THROUGH THE MAJORITY OF THE EXTENDED PERIOD. FAST ZONAL FLOW WILL BE OVER THE FORECAST AREA THROUGH THE PERIOD. CUT OFF LOW OVER CENTRAL CALIFORNIA WILL REMAIN IN PLACE MONDAY THROUGH WEDNESDAY EJECTING PIECES OF ENERGY EAST ACROSS WYOMING AND COLORADO. MAIN JET WILL STAY ACROSS SOUTHERN CANADA THROUGH THE PERIOD KEEPING THE MAJORITY OF THE UPPER LEVEL ENERGY ACROSS THAT AREA. AS A RESULT...QUIET ZONAL FLOW LOOKS TO BE IN STORE FOR OUR AREA THROUGH THE PERIOD. WITH NO LARGE TROUGH OR RIDGE EXPECTED...NO BIG WARM UP OR COOL DOWN EXPECTED EITHER WITH TEMPERATURES STAYING VERY CLOSE TO NORMAL OR SLIGHTLY ABOVE. MODELS DIVERGE BY NEXT FRIDAY WITH THE GFS PLACING THE AREA UNDER A NORTHWEST FLOW ALOFT WHILE THE ECMWF CARVES A TROUGH ACROSS THE PACIFIC NORTHWEST RESULTING IN AN UNSETTLED SOUTHWEST FLOW ALOFT TO THE AREA. DUE TO UNCERTAINTIES...WILL CONTINUE WITH DRY FORECAST FOR THE END OF NEXT WEEK. HOOLEY && .AVIATION... IFR CONDITIONS WILL SPREAD ACROSS ALL BUT THE EXTREME SOUTHERN PORTION OF THE AREA BY MID DAY AS PRECIPITATION INCREASES FROM SOUTHWEST TO NORTHEAST. CEILINGS ARE ALREADY BELOW 1000 FEET IN BAKER AND MILES CITY AND WILL DROP TO AROUND 1000 FEET IN BILLINGS AND LIVINGSTON BY NOON. MVFR CONDITIONS WILL DEVELOP IN SHERIDAN THIS AFTERNOON WITH IFR CONDITIONS BY THIS EVENING. EXPECT IFR CEILINGS TO CONTINUE TONIGHT WITH RAIN AND DEVELOPING FOG DIMINISHING VISIBILITIES FURTHER OVERNIGHT TONIGHT. CHAMBERS && .PRELIMINARY POINT TEMP/POPS... TDY SUN MON TUE WED THU FRI ------------------------------------------------------- BIL 061 046/067 047/077 048/075 047/074 045/070 045/068 6/W 63/W 00/U 00/B 00/B 00/B 00/B LVM 056 036/065 035/075 042/073 040/072 037/069 037/068 8/W 72/W 00/U 00/B 00/B 00/B 00/U HDN 065 046/069 044/080 045/079 045/077 046/072 044/070 6/W 63/T 20/U 00/B 00/B 00/B 00/B MLS 064 047/068 045/080 045/078 045/076 044/072 044/069 3/R 43/W 00/U 00/B 00/B 00/B 00/B 4BQ 070 047/069 043/077 045/078 044/076 043/072 042/071 3/T 43/T 20/U 00/B 00/B 00/B 00/B BHK 063 045/065 041/076 043/077 043/075 041/070 040/069 3/R 33/W 00/U 00/B 00/B 00/B 00/B SHR 066 044/068 038/078 041/078 040/077 039/072 039/071 4/T 43/T 20/U 00/B 00/B 00/B 00/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1000 AM EDT SAT SEP 17 2005 .SHORT TERM (REST OF TODAY)...REAL TIME OBSERVATIONS AND SHORT TERM PROJECTIONS BY RUC MODEL BOTH SUPPORT CURRENT FORECAST FOR THE REMAINDER OF THE DAY. NO UPDATES NEEDED AT THIS TIME. THE HIGHER CHANCE (30 PERCENT) FOR AFTERNOON CONVECTIVE STORMS IS ALONG THE EASTERN TIER OF THE FORECAST AREA. WHILE DRYING ALOFT CONTINUES TO PROGRESS EASTWARD...THE AIRMASS OVER EASTERN SECTIONS OF CENTRAL NORTH CAROLINA IS QUITE UNSTABLE WITH SOME LINGERING MOISTURE. WEAK LOW LEVEL CONVERGENCE ASSOCIATED WITH SURFACE TROUGH AND A WEAK CHANNELED VORTICITY IMPULSE LOCATED OVER CENTRAL NORTH CAROLINA AT THE TIME OF MAX HEATING THIS AFTERNOON SHOULD PROVIDE SUPPORT FOR SCATTERED SHOWERS AND THUNDERSTORMS...MORE SO JUST EAST OF THE FORECAST AREA. THE 24 HOUR CHANGE IN TEMPERATURES AND THIS MORNING'S SLIGHTLY LOWER LOW LEVEL THICKNESS VALUES BOTH SUPPORT DAYTIME HIGH TEMPERATURES A FEW DEGREES BELOW YESTERDAY'S. && .PREVIOUS DISCUSSION... (ISSUED 245 AM EDT SAT SEP 17 2005) SHORT TERM (TODAY THROUGH WEDNESDAY)... THROUGH TODAY: ISOLATED SHOWERS CONTINUE TO FIRE WITHIN THE LOW-LEVEL MOISTURE-RICH AND MARGINALLY UNSTABLE AIR MASS EAST OF I-95... LIKELY SUPPORTED BY WEAK PVA ACCORDING TO PRE-ECLIPSE WATER VAPOR IMAGERY. THESE SHOWERS SHOULD DIMINISH TOWARD DAWN WITH A DECREASING UPWARD SURFACE HEAT FLUX & THE EXITING OF THE VORT MAX. THE CONVECTIVE BAND UPSTREAM NEAR THE SURFACE FRONT & MID LEVEL TROUGH OVER WV/SWRN VA APPEARS TO BE WEAKENING... BUT AS THIS FRONT DROPS EAST OF THE MOUNTAINS LATER TODAY... REDEVELOPMENT IS POSSIBLE. BOTH THE GFS AND THE NAM SHOW DECENT INSTABILITY WITH LI VALUES -2 TO -5... PRECIPITABLE WATER NEAR 150% OF NORMAL... CAPE VALUES NEARING (NAM) OR EXCEEDING (GFS) 1000 J/KG... AND MID LEVEL LAPSE RATES NEAR 6 C/KM... AND ALL OF THIS IS WITH THE MODELS DEVELOPING VARYING DEGREES OF CAPPING AROUND 600 MB. WITH POTENTIAL MECHANICAL FORCING CONTRIBUTIONS FROM WEAK LOW LEVEL CONVERGENCE AND DIVERGENCE ALOFT AS THE LEFT EXIT REGION OF THE INCOMING 300 MB JET APPROACHES... WILL BRING IN ISOLATED STORMS OVER THE EASTERN PIEDMONT AND SANDHILLS... WITH MORE SCATTERED STORMS OVER THE COASTAL PLAIN. MODEL FORECAST THICKNESSES PLUS A DRY ADIABATIC LOW LEVEL PROFILE SUPPORT A SLIGHT UPWARD TICK TO HIGH TEMPS... MAINLY 88-94. TONIGHT: MID LEVEL VORT MAX AND UPPER JET FORCING BOTH EXIT THE PICTURE EARLY WITH THE SURFACE FRONT PUSHING INTO THE COASTAL AREA. A STORM OR TWO COULD LINGER EAST OF I-95 INTO THE EVENING BUT BELIEVE THE BEST INSTABILITY WILL KICK EASTWARD EARLY. THE AMOUNT OF LOW LEVEL DRYING IS QUESTIONABLE WITH DEWPOINTS UNLIKELY TO DROP MUCH BELOW THE MID 60S... & WILL RAISE OVERNIGHT MINS A DEGREE OR SO... WITH CLEARING SKIES. SUNDAY THROUGH WEDNESDAY: UPPER RIDGING BUILDS OVER THE WEST GULF STATES AND DRIFTS SLOWLY TOWARD OK/TX THROUGH THE PERIOD... WHILE MID LEVEL PERTURBATIONS DROP ESE ATOP THE RIDGE THROUGH NC. FORCING AND MOISTURE APPEAR TOO LIMITED SUNDAY/MONDAY FOR ANY PRECIP CHANCES... HOWEVER THE NAM/GFS/ECMWF INDICATE A MORE POTENT NORTHERN STREAM WAVE PUSHING THROUGH THE EASTERN GREAT LAKES REGION & OFF THE NEW ENGLAND COAST TUE/WED... BRINGING A FRONT INTO THE AREA. THIS WARRANTS AT LEAST A SLIGHT CHANCE POP... WHICH MAY NEED TO BE INCREASED IN LATER FORECASTS IF THE MODELS STICK WITH THIS SOLUTION. LITTLE CHANGE TO TEMPS. LONG TERM (WEDNESDAY NIGHT THROUGH FRIDAY)... SEE NO COMPELLING REASON TO MAKE CHANGES TO CURRENT DRY FORECAST... WITH THE ECMWF/GFS SHOWING BROAD RIDGING DEVELOPING FROM THE SRN PLAINS TO THE MID-ATLANTIC REGION. AVIATION... LOW-LEVEL INVERSION SEEN IN 00Z GSO WILL TRAP MOISTURE AND RAINED COOL AIR FROM THIS PAST EVENING'S SHOWERS WITH NEARLY ALL SITES REPORTING CALM WINDS...HIGH RH AND CLEAR SKIES. RAINFALL DISTRIBUTION FROM EVENING RAINFALL WILL MAKE VISIBILITY RESTRICTIONS HIGHLY VARIABLE...RANGING FROM MVFR TO LIFR. GOING STRICTLY ON A PERSISTENCE FORECAST OF 24 HOURS AGO AND WEIGHTED TOWARDS THE LAMP GUIDANCE...FORECAST LIFR VISIBILITY RESTRICTION AT RDU AND RWI TAF SITES. KEPT GSO...INT...AND FAY. MORNING SUN SHOULD BEGIN TO MIX BL BETWEEN 14-15Z WITH VFR CONDITIONS EXPECTED THROUGH THE REMAINING OF THE FORECAST PERIOD. CANNOT ENTIRELY RULE OUT AN ISOLATED TSRA TOMORROW AFTERNOON...ESPECIALLY ACROSS EASTERN TAF SITES AS FRONT MOVES ACROSS THE AREA. HOWEVER POD OF TSRA AT TAF SITES IS VERY LOW AND WILL NOT INCLUDE. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...KK nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 932 AM EDT SAT SEP 17 2005 .SHORT TERM (REST OF TODAY)... WILL REMOVE MORNING FOG AND LOWER DEW POINT TEMPERATURES TODAY BASED ON CURRENT OBSERVATIONS. THE WATER VAPOR LOOP INDICATES A SHORTWAVE TROUGH SHOULD BE EAST OF THE FORECAST AREA LATER THIS AFTERNOON. THE LATEST RUC SHOWS H5 WARM ADVECTION THIS AFTERNOON. MOISTURE APPEARS SHALLOW. THE COLD FRONT APPROACHING THE FORECAST AREA APPEARS DIFFUSE WITH LITTLE CONVERGENCE. EXPECT THUNDERSTORMS ASSOCIATED WITH THE FRONT AND HEATING WILL BE ISOLATED AT MOST THIS AFTERNOON...BUT LARGE TEMPERATURE-DEW POINT TEMPERATURE SPREADS AND MODERATE INSTABILITY SUPPORT STRONG WIND GUSTS IF THUNDERSTORMS DO DEVELOP. && .PREVIOUS DISCUSSION... (ISSUED 250 AM EDT SAT SEP 17 2005) SHORT TERM (TODAY THROUGH SUNDAY)... WK CDFNT MOVS INTO AREA TDA WTH SOME CONVERGENCE ALG BNDRY. UPR SUPP RMNS WK AND MNLY N OF AREA. WTH DWPTS UPR 60S AMS BCM MODERATELY UNSTBL ALG FNTL BNDRY BUT DEEP MSTR NOT AVBL. HWVR DRIER AMS MOVS INTO AREAS FROM W BY MID AFTN SO ANY CNVECTION WL LIKELY OCCUR IN ERN SECTS. WL CARRY ISOLATED POPS FOR CONVERGENCE ALG FNT. LONG TERM (SUNDAY NIGHT THROUGH FRIDAY)... CDFNT MOVS ACRS AREA THS WEEKEND AND SLGTLY DRIER AND LTL COOLER AMS WL DOMINATE FCST FOR RMDR OF WK. AVIATION... COLD FRONT IN EASTERN TN WILL CONTINUE TO MOVE SLOW EASTWARD TODAY REACHING THE EASTERN SECTIONS OF THE CWA AROUND 00Z. FEW AREAS OF MVFR VSBYS BR THRU 12Z WITH ISOLATED AREAS OF IFR VSBYS BR. GENERALLY VFR AFTER 12Z WITH ISOLATED TSRA 16Z-01Z. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ 05 sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 1108 AM CDT SAT SEP 17 2005 .UPDATE FRONTAL BOUNDARY STILL DRAPED FROM BETWEEN PHP AND PIR THEN NE BETWEEN PIR AND MBG...THEN HEADS NE INTO ND. DECK OF LOW CLOUDS ACROSS ND LATE THIS MORNING HAS NOT MOVED SOUTH MUCH FURTHER AND RUC ALSO SUGGESTS NO MOVEMENT FURTHER SOUTH. LOWERED HIGHS A BIT ACROSS THE MBG AREA IN POST FRONTAL ENVIRONMENT WHERE TEMPS HAVE STRUGGLED TO CLIMB THIS MORNING. INCREASED WINDS ACROSS THE EAST WHERE BREEZY CONDITIONS HAVE DEVELOPED. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ TMT sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 215 PM MDT SAT SEP 17 2005 .SHORT TERM... (TONIGHT - TUESDAY) SHORTWAVE/SURFACE COLD FRONT CURRENTLY OVER THE NORTHERN PLAINS ENCOUNTERING PLENTY OF RESISTANCE FROM STRONG UPPER RIDGE CENTERED OVER THE SOUTHERN PLAINS. PREFRONTAL TROUGH/DRY LINE EXTENDS SOUTH ACROSS THE FORECAST AREA FROM FRONTAL WAVE NEAR KPIR IN SD. VERY DIFFICULT TO TRACK FRONTAL MOVEMENT IN THE MODEL FORECASTS...BUT 24 HOUR THICKNESS CHANGES DO SUGGEST SLIGHTLY COOLER TEMPERATURES ON SUNDAY...BUT THIS MAY SIMPLY BE ON THE WEST SIDE OF PREFRONTAL TROUGH. TRUE FRONT MAY NOT ARRIVE UNTIL SUNDAY NIGHT AS UPPER LEVEL FLOW VEERS TO NORTHWESTERLY ON BACKSIDE OF SHORTWAVE DIGGING INTO THE MISSISSIPPI RIVER VALLEY...GIVING BETTER SUPPORT TO SURFACE FEATURES. PRECIPITATION CHANCES STILL LOOK MINIMAL AS BEST DYNAMICS STAY TO THE NORTHEAST AND SURFACE UPSLOPE FLOW THAT DOES FINALLY DEVELOP LATE SUNDAY QUITE WEAK. GFS SURFACE RH AND RUC20 VIS/CEILING FORECASTS SUGGEST STRATUS/FOG POSSIBLE TONIGHT IN NORTHEAST CORNER OF CWA AND AGAIN SUNDAY NIGHT SOUTH OF THE INTERSTATE ALONG LEADING EDGE OF COOLER AIR. MONDAY/TUESDAY...UPPER RIDGING WILL REBUILD ALOFT AND RETURN FLOW QUICKLY ESTABLISHED AT THE SURFACE. MAV GUIDANCE LOOKS TO BE WARMING UP TOO QUICKLY AND WILL GO CLOSER TO COOLER MET/FWC GUIDANCE FOR TEMPERATURES. GFS FORECASTING GOOD BIT OF INSTABILITY DEVELOPING OVER EASTERN HALF BY TUESDAY AFTERNOON...BUT UPPER RIDGE AXIS WILL BE ALMOST DIRECTLY OVERHEAD AND THUS NO FORCING. STILL INDICATIONS OF A SHORTWAVE TUESDAY NIGHT RIDING BACKSIDE OF RIDGE OUT OF COLORADO...ALTHOUGH LATEST TRACK WOULD KEEP IT NORTHWEST OF THE CWA. NOCTURNAL BOUNDARY LAYER COOLING WILL RESULT IN STABLE ATMOSPHERE AND WILL GO AHEAD AND PULL THE POPS TUESDAY NIGHT. .LONG TERM... (WEDNESDAY - SATURDAY) UPPER RIDGE ANCHORED OVER TEXAS-LOUISIANA THIS PERIOD WILL BE DOMINANT UPPER FEATURE. A COUPLE OF SHORTWAVES WILL COME OVER THE RIDGE. NORTHERN STREAM TROUGH WILL DIG ALONG THE PACIFIC NORTHWEST COAST...AND KICK OUT A SOUTHERN STREAM SHORTWAVE OVER CALIFORNIA. THE LEAD WAVE DAMPENS QUITE A BIT AS IT EJECTS INTO THE NORTHERN PLAINS WEDNESDAY OR THURSDAY...ECMWF BEING ABOUT 24 HOURS FASTER THAN THE OPERATIONAL GFS. THOSE TWO MODELS DIVERGE EVEN MORE WITH THE NORTHERN STREAM SYSTEM...ECMWF DIGGING IT DEEPLY INTO THE WESTERN CONUS BUT OPERATIONAL GFS BRINGING IT INTO THE NORTHERN PLAINS LATE IN THE PERIOD. NCEP ENSEMBLE MEAN AND GFS SPAGHETTI PLOTS SUPPORT THE GFS OVER THE ECMWF SOLUTION. WILL HAVE SOME SLIGHT CHANCES WEDNESDAY NIGHT IN NORTHWEST HALF WITH LEAD SHORTWAVE. NEXT CHANCE WOULD COME FRIDAY NIGHT WITH NORTHERN STREAM SYSTEM...BUT WITH POOR MODEL AGREEMENT WILL KEEP POPS UNDER 15 PERCENT AT THIS POINT. WILL BE FOLLOWING THE TEMPERATURE TRENDS OF THE GFS WITH COOLING TOWARDS THE END OF THE PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ JDK ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 630 PM EDT SAT SEP 17 2005 .AVIATION...LIGHT RAIN SHOWERS DIMINISHING RAPIDLY AND SHOULD BE GONE BY 00Z. IN ADDITION CU FIELD ALSO BEGINNING TO BREAK UP AS DRY AIR ADVECTION OCCURS NEAR THE SURFACE AND WITH LOSS OF DAYTIME HEATING. SURFACE DEW POINTS ALREADY INTO THE MID 40S ACROSS NORTHERN PORTION OF REGION...SO ANTICIPATE JUST SCATTERED CU FIELD BY 00Z FROM FNT SOUTHWARD TO DTW. SURFACE HIGH TO REMAIN OVER THE REGION OVERNIGHT SO FOG BECOMES A CONCERN. THIS WILL BE PARTLY OFFSET BY LOW LEVEL DRY ADVECTION...SO ANTICIPATE AREAS OF MVFR FOG AT THIS TIME. AREA THAT IS MOST LIKELY TO SEE MORE EXTENSIVE FOG WILL BE DTW/DET AREAS WHERE NO MIXING TOOK PLACE TODAY AND BOUNDARY LAYER MOISTURE MORE ABUNDANT THERE. IN ADDITION SOME SCATTERED MID LEVEL CLOUD DEBRIS FROM CONVECTION OVER WISCONSIN TO MOVE ACROSS THE NORTHERN PORTION OF THE REGION AFTER 06Z...WHICH WILL LIMIT RADIATIONAL COOLING THERE. ONLY SCATTERED CU ANTICIPATED AFTER 16Z. .SHORT TERM...TONIGHT AND SUNDAY...ISSUED AT 331 PM SURFACE ANALYSIS SHOWS HIGH PRESSURE OVER LAKE MICHIGAN/NORTHERN LAKE HURON...BUT WITH WEAK CYCLONIC FLOW LINGERING ACROSS FAR SOUTHEAST LOWER MICHIGAN. 18Z-19Z ACARS SOUNDINGS VICINITY OF DTW SHOW LITTLE CHANGE SINCE 12Z IN THE AMOUNT OF LOW-LEVEL MOISTURE TRAPPED BELOW THE 700MB SUBSIDENCE INVERSION. VIS SATELLITE/METARS SHOW A SOLID LOW CLOUD DECK ACROSS MUCH OF THE CWA. DTX RADAR EVEN SHOWS WEAK ECHOES CONTINUING IN THE NORTHEAST FLOW DOWNSTREAM FROM LAKE HURON. 15Z/18Z RUC FORECAST SOUNDINGS CONTINUE TO BE TOO AGGRESSIVE IN DRYING OUT THE COLUMN ACROSS SOUTHEAST MICHIGAN. CLOUDS HAVE PERSISTENT THROUGH THE DAY WITH SOME DIURNAL ENHANCEMENT APPARENT ON SATELLITE IMAGERY...ESPECIALLY ACROSS THE NORTHERN CWA. EXPECT THE NORTHERN EXTENT OF THE CLOUDS TO QUICKLY ERODE TOWARD SUNSET... ALTHOUGH WITH THICKER CLOUDS OVER THE SOUTHERN CWA HOLDING ON INTO/THROUGH THE EVENING. ADDED A MENTION OF SPRINKLES EARLY AS WELL ACROSS THE SOUTH...BASED ON WEAK RADAR ECHOES. HIGH PRESSURE WILL EVENTUALLY BUILD DOWN ACROSS SOUTHEAST MICHIGAN...ALTHOUGH WITH THE FAR SOUTHEAST NOT CLEARING OUT UNTIL LATE. WEAK GRADIENT AND CLEARING SKIES UNDER THE HIGH WILL ALLOW FOR GOOD RADIATIONAL COOLING...ESPECIALLY ACROSS THE NORTHERN CWA. SURFACE HIGH SHIFTS EAST ON SUNDAY AS THE NEXT SYSTEM STARTS TAKING SHAPE TO THE WEST OF THE REGION. WEAK SOUTHWESTERLY RETURN FLOW SETS UP...WITH WINDS TURNING MORE OFFSHORE DURING THE DAY. WEAK WARM ADVECTION LEADS TO 850MB TEMPS A DEGREE OR SO HIGHER THAN TODAY...ALTHOUGH WITH BETTER INSOLATION HIGHS ACROSS THE SOUTHERN CWA WILL BE A SOLID 5-8F WARMER THAN TODAY. && .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY...ISSUED AT 331 PM A BROAD UPPER LEVEL SHORT WAVE TROUGH NOW EXTENDING ACROSS OREGON AND IDAHO WILL LIFT INTO THE NORTHERN PLAINS ON SUNDAY... THEN ACROSS THE NORTHERN GREAT LAKES BY MONDAY. THE 12Z MODEL SUITE ARE OVERALL IN BETTER AGREEMENT WITH THIS SYSTEM COMPARED TO PREVIOUS RUNS. BASED ON THE 12Z UPPER AIR PLOTS AND WATER VAPOR... THE 12Z SUITE STILL SEEM TO BE A LITTLE TOO WEAK WITH THE CIRCULATION... ESPECIALLY THE NAM. THE 12Z MODEL SUITE ALL INDICATE A DEEPENING SURFACE LOW ACROSS THE UPPER MISSISSIPPI VALLEY SUNDAY NIGHT UNDER GOOD UPPER JET COUPLING. THE SURFACE LOW THEN LIFTS ACROSS UPPER MICHIGAN DURING THE DAY MONDAY. THIS LOW WILL DRAG AN ASSOCIATED COLD FRONT ACROSS LOWER MICHIGAN ON MONDAY. GIVEN THE BETTER INITIALIZATION... PREFER THE SLOWER GFS SOLUTION ON MONDAY... WHICH DOES NOT BRING THE SURFACE COLD FRONT ACROSS SE MICHIGAN UNTIL LATE MONDAY EVENING. ALTHOUGH THE STRONGEST UPPER DIVERGENCE WILL LIFT NORTH OF THE FORECAST AREA ON MONDAY... STRONG DCVA AHEAD OF THE SHORT WAVE TROUGH COMBINED WITH AN AXIS OF HIGH LOW LEVEL THETA E ALONG THE FRONTAL BOUNDARY STILL WARRANTS A CHANCE OF SHOWERS AND THUNDERSTORMS. BASED MORE HEAVILY TOWARD THE GFS TIMING AND GIVEN THE MOIST AXIS IS EXPECTED TO BE VERY NARROW... WILL CONFINE THE BULK OF THE POPS FROM MID AFTERNOON MONDAY THROUGH MONDAY EVENING. DEEP LAYER SHEAR WILL BE RATHER STRONG AS A 50-60KT MID LEVEL JET NOSES ACROSS SOUTHERN MICHIGAN MONDAY EVENING IN THE BASE OF THE UPPER TROUGH. THIS WILL CREATE AN INCREASED RISK OF STRONG TO SEVERE THUNDERSTORMS. THE LIMITING FACTOR HOWEVER... AS USUALLY IS THE CASE THIS TIME OF YEAR... WILL BE THE AMOUNT OF INSTABILITY. THE NAM SOLUTION INDICATES AROUND 1500 J/KG SBCAPE. THIS HOWEVER SEEMS OVERDONE DUE TO UNREALISTICALLY HIGH SURFACE DEWPOINTS. THE GFS SOLUTION... WHICH BRINGS SURFACE DEWPOINTS OF LOWER 60S INTO SE MICHIGAN BY MONDAY EVENING... ONLY HAS A FEW HUNDRED J/KG OF CAPE. CONVECTIVE DEBRIS FROM UPSTREAM MCS ACTIVITY SUN NIGHT MAY ALSO LIMIT THE AMOUNT OF HEATING ON MONDAY. GIVEN THE SHEAR THOUGH... WILL STILL RETAIN THE POTENTIAL FOR STRONG TO SEVERE STORMS IN THE HWO. THE GFS...WRFXX AND UKMET SOLUTIONS INDICATE THE STRONGEST INSTABILITY WILL RESIDE SOUTH OF THE STATE. THESE SOLUTIONS ACTUALLY INDICATE VERY LITTLE QPF OVER SE MICHIGAN AS STRONG CONVECTION DEVELOPS OVER IL AND IN... INTERCEPTING SOME OF THE MOISTURE TRANSPORT INTO SE MICHIGAN. FOR THIS REASON... WILL KEEP POPS IN THE LOW CHANCE CATEGORY AT THIS TIME. RIDGING IS STILL EXPECTED TO BUILD BACK INTO THE REGION BY MIDWEEK... PROVIDING DRY CONDITIONS. AN UPPER LOW THAT DEVELOPS OFF THE COAST OF CALIFORNIA EARLY IN THE WEEK IS EXPECTED TO LIFT INTO THE GREAT LAKES REGION BY THE END OF THE WEEK... SHEARING OUT QUITE A BIT AS IT ENCOUNTERS THE STRONG RIDGE OVER THE CENTRAL US. BASED ON THE 12Z GFS AND WRFXX... WILL RETAIN A CHANCE OF CONVECTION LATE IN THE WEEK. THE EUROPEAN AND CANADIAN SOLUTIONS HOWEVER ARE STILL MORE AMPLIFIED WITH AN UPPER TROUGH THAT DEVELOPS OVER WESTERN CANADIAN AND THE NW US BY THE END OF THE WEEK AND THUS HAVE HIGHER HEIGHTS OVER THE EASTERN US. THIS MAY CAUSE THE BULK OF THE SHORT WAVE ENERGY TO PASS NORTH OF SE MICHIGAN. GIVEN THE ABOVE NORMAL HEIGHTS EXPECTED OVER THE EASTERN US THROUGH THE END OF THE WEEK... WILL CONTINUE TO FORECAST ABOVE NORMAL TEMPS WED THROUGH SAT. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BRAVENDER LONG TERM....CONSIDINE AVIATION.....GSS mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 PM EDT SAT SEP 17 2005 .DISCUSSION... MAIN FCST ISSUES ARE PCPN CHANCES TONIGHT THRU MON. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF OVER THE PACIFIC NW WITH WSW FLOW FROM THE WRN CONUS TO THE GREAT LAKES. SHORTWAVE ENERGY OVER THE PACIFIC NW WILL BE A FACTOR IN PCPN CHANCES HERE SUN NIGHT/MON. BEFORE THEN...COMBINATION OF SHORTWAVE CURRENTLY OVER THE CNTRL PLAINS AND A NRN STREAM SHORTWAVE OVER SASKATCHEWAN WILL AFFECT THE UPPER GREAT LAKES TONIGHT/SUN. SCT SHRA/TSRA HAVE BEEN OCCURRING THIS AFTN OVER ERN SD/SRN MN/NW IA AHEAD OF THE CNTRL PLAINS WAVE. AT THE SFC...FRONTAL BOUNDARY RUNS FROM CNTRL SD TO FAR NW MN AND WRN ONTARIO. CLOSER TO HOME...MID/HIGH CLOUDS HAVE INCREASED OVER WRN UPPER MI THIS AFTN...BUT SKIES REMAIN MOSTLY SUNNY OVER THE E. TEMPS HAVE CLIMBED WELL ABOVE NORMAL INTO THE MID 70S TO AROUND 80. SHORTWAVE PRODUCING SHRA/TSRA ACROSS SW MN WILL LIFT NE ACROSS UPPER MI TONIGHT...ACCOMPANIED BY DECENT ISENTROPIC ASCENT AND WEAK DEEP LAYER QVECTOR CONVERGENCE. APPEARS GFS HAS THE BEST HANDLE ON THE SITUATION SINCE IT HAS A BETTER DEPICTION OF THE CURRENT PCPN AREA. GIVEN THE WEAK FORCING AND THE FACT THAT SHRA/TSRA ARE ASSOCIATED WITH SHORTWAVE NOW...SEEMS REASONABLE THAT PCPN WILL LIFT NE INTO UPPER MI DURING THE NIGHT. HOWEVER...UPSTREAM SOUNDINGS AT KMPX/KABR/KOAX SHOW LIMITED MOISTURE...SO COVERAGE OF SHRA/TSRA SHOULD BE SCT...AND PCPN AMOUNTS SHOULD BE LIGHT. BASED ON TRACK OF SHORTWAVE/FORCING...WILL KEEP THE ERN COUNTIES DRY TONIGHT. MIN TEMPS WILL BE WELL ABOVE NORMAL IN THE 50S WITH READINGS AROUND 60 IN THE AREAS THAT DOWNSLOPE IN SRLY FLOW. ON SUN...NRN STREAM SHORTWAVE CURRENTLY OVER SASKATCHEWAN WILL MOVE ACROSS ONTARIO...PUSHING COLD FRONT ACROSS UPPER MI. DYNAMICS ARE WEAK AT BEST...BUT WITH SHARP DIRECTIONAL CONVERGENCE SETTING UP ALONG FRONT (ESPECIALLY OVER THE E HALF OF FCST AREA DUE TO LAKE BREEZE COMPONENT TO WIND) AND MLCAPE INCREASING UPWARDS OF 500J/KG...EXPECT SCT SHRA/TSRA TO DEVELOP ALONG FRONT AS IT DROPS SSE ACROSS THE AREA. ALTHOUGH DEEP LAYER SHEAR IS 30-35KT...BELIEVE LACK OF CAPE WILL KEEP ANY STORMS BLO SVR LIMITS. MODELS HAVE TRENDED TO MUCH BETTER AGREEMENT ON TAKING SHORTWAVE ENERGY CURRENTLY OVER THE PACIFIC NW INTO THE GREAT LAKES ON MON. IT NOW LOOKS LIKE THIS SYSTEM WILL BRING DECENT PCPN TO ALL OF THE FCST AREA LATE SUN NIGHT AND MON AS HEALTHY DYNAMICS INCLUDING COUPLED UPPER JET STRUCTURE FOCUS OVER THE AREA. WILL UP POPS TO LIKELY ACROSS THE FCST AREA (CATEGORICAL POPS WILL PROBABLY BE REQUIRED EVENTUALLY). PREFER TO LEAN TOWARD THE SLOWER PCPN TIMING SHOWN BY GFS/CANADIAN/UKMET MODELS...AND WILL BRING PCPN INTO THE W AND SW AFTER MIDNIGHT SUN NIGHT AND SPREAD TO THE E MON MORNING. WILL ALSO FAVOR COOLER SIDE OF VARIOUS MOS GUIDANCE MON...ASSUMING PCPN IS FALLING FOR MUCH OF THE DAY. SHRA WILL END FROM W TO E LATE MON INTO MON EVENING WITH PARTIAL CLEARING AS SFC RIDGE AXIS REACHES WRN UPPER MI BY 12Z TUE. WILL RAISE MINS UP SEVERAL DEGREES FROM GOING FCST DUE TO CLOUDS BEING SLOWER TO PULL OUT. TUE LOOKS LIKE A NICE DAY UNDER PARTLY/MOSTLY SUNNY SKIES AND A WSW FLOW. MIXING TO 850MB ON FCST SOUNDINGS YIELDS HIGHS INTO THE LOW/MID 70S. WED-SAT...00Z GFS/CANADIAN/ECMWF/UKMET ARE IN DECENT AGREEMENT FOR THIS PERIOD AND ARE SUGGESTING AN ACTIVE PERIOD WITH 2 POTENTIALLY SIGNIFICANT PCPN EVENTS. OVERALL PATTERN WILL FEATURE MEAN TROFFING OVER THE W WITH WSW FLOW INTO THE GREAT LAKES. FIRST WAVE WILL LIFT INTO THE UPPER GREAT LAKES EARLY THU. ECWMF IS A LITTLE QUICKER THAN THE UKMET AND 00Z/06Z GFS AND WOULD SUGGEST PCPN BREAKING OUT AS EARLY AS WED AFTN. WILL FOLLOW THE SLIGHTLY SLOWER CONSENSUS WHICH IS MORE INLINE WITH GOING FCST...AND WILL SPREAD POPS ACROSS THE AREA WED NIGHT...THEN ENDING THU. AFTER A BREAK THU NIGHT/FRI...GFS/ECMWF SHOW GOOD AGREEMENT ON THE NEXT WAVE STREAKING INTO THE UPPER LAKES REGION FRI NIGHT/SAT. WILL SPREAD POPS W TO E ACROSS THE AREA AT THAT TIME. BOTH PCPN EVENTS (WED NIGHT/THU AND FRI NIGHT/SAT) WILL PROBABLY REQUIRE HIGH POPS...BUT DUE TO TIMING UNCERTAINTIES AT THIS TIME RANGE...WILL KEEP POPS IN THE CHC RANGE. TEMPS SHOULD BE A LITTLE ABOVE NORMAL ON MOST DAYS DURING THIS PERIOD. && .MQT...WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 331 PM EDT SAT SEP 17 2005 .SHORT TERM...TONIGHT AND SUNDAY SURFACE ANALYSIS SHOWS HIGH PRESSURE OVER LAKE MICHIGAN/NORTHERN LAKE HURON...BUT WITH WEAK CYCLONIC FLOW LINGERING ACROSS FAR SOUTHEAST LOWER MICHIGAN. 18Z-19Z ACARS SOUNDINGS VICINITY OF DTW SHOW LITTLE CHANGE SINCE 12Z IN THE AMOUNT OF LOW-LEVEL MOISTURE TRAPPED BELOW THE 700MB SUBSIDENCE INVERSION. VIS SATELLITE/METARS SHOW A SOLID LOW CLOUD DECK ACROSS MUCH OF THE CWA. DTX RADAR EVEN SHOWS WEAK ECHOES CONTINUING IN THE NORTHEAST FLOW DOWNSTREAM FROM LAKE HURON. 15Z/18Z RUC FORECAST SOUNDINGS CONTINUE TO BE TOO AGGRESSIVE IN DRYING OUT THE COLUMN ACROSS SOUTHEAST MICHIGAN. CLOUDS HAVE PERSISTENT THROUGH THE DAY WITH SOME DIURNAL ENHANCEMENT APPARENT ON SATELLITE IMAGERY...ESPECIALLY ACROSS THE NORTHERN CWA. EXPECT THE NORTHERN EXTENT OF THE CLOUDS TO QUICKLY ERODE TOWARD SUNSET... ALTHOUGH WITH THICKER CLOUDS OVER THE SOUTHERN CWA HOLDING ON INTO/THROUGH THE EVENING. ADDED A MENTION OF SPRINKLES EARLY AS WELL ACROSS THE SOUTH...BASED ON WEAK RADAR ECHOES. HIGH PRESSURE WILL EVENTUALLY BUILD DOWN ACROSS SOUTHEAST MICHIGAN...ALTHOUGH WITH THE FAR SOUTHEAST NOT CLEARING OUT UNTIL LATE. WEAK GRADIENT AND CLEARING SKIES UNDER THE HIGH WILL ALLOW FOR GOOD RADIATIONAL COOLING...ESPECIALLY ACROSS THE NORTHERN CWA. SURFACE HIGH SHIFTS EAST ON SUNDAY AS THE NEXT SYSTEM STARTS TAKING SHAPE TO THE WEST OF THE REGION. WEAK SOUTHWESTERLY RETURN FLOW SETS UP...WITH WINDS TURNING MORE OFFSHORE DURING THE DAY. WEAK WARM ADVECTION LEADS TO 850MB TEMPS A DEGREE OR SO HIGHER THAN TODAY...ALTHOUGH WITH BETTER INSOLATION HIGHS ACROSS THE SOUTHERN CWA WILL BE A SOLID 5-8F WARMER THAN TODAY. && .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY A BROAD UPPER LEVEL SHORT WAVE TROUGH NOW EXTENDING ACROSS OREGON AND IDAHO WILL LIFT INTO THE NORTHERN PLAINS ON SUNDAY... THEN ACROSS THE NORTHERN GREAT LAKES BY MONDAY. THE 12Z MODEL SUITE ARE OVERALL IN BETTER AGREEMENT WITH THIS SYSTEM COMPARED TO PREVIOUS RUNS. BASED ON THE 12Z UPPER AIR PLOTS AND WATER VAPOR... THE 12Z SUITE STILL SEEM TO BE A LITTLE TOO WEAK WITH THE CIRCULATION... ESPECIALLY THE NAM. THE 12Z MODEL SUITE ALL INDICATE A DEEPENING SURFACE LOW ACROSS THE UPPER MISSISSIPPI VALLEY SUNDAY NIGHT UNDER GOOD UPPER JET COUPLING. THE SURFACE LOW THEN LIFTS ACROSS UPPER MICHIGAN DURING THE DAY MONDAY. THIS LOW WILL DRAG AN ASSOCIATED COLD FRONT ACROSS LOWER MICHIGAN ON MONDAY. GIVEN THE BETTER INITIALIZATION... PREFER THE SLOWER GFS SOLUTION ON MONDAY... WHICH DOES NOT BRING THE SURFACE COLD FRONT ACROSS SE MICHIGAN UNTIL LATE MONDAY EVENING. ALTHOUGH THE STRONGEST UPPER DIVERGENCE WILL LIFT NORTH OF THE FORECAST AREA ON MONDAY... STRONG DCVA AHEAD OF THE SHORT WAVE TROUGH COMBINED WITH AN AXIS OF HIGH LOW LEVEL THETA E ALONG THE FRONTAL BOUNDARY STILL WARRANTS A CHANCE OF SHOWERS AND THUNDERSTORMS. BASED MORE HEAVILY TOWARD THE GFS TIMING AND GIVEN THE MOIST AXIS IS EXPECTED TO BE VERY NARROW... WILL CONFINE THE BULK OF THE POPS FROM MID AFTERNOON MONDAY THROUGH MONDAY EVENING. DEEP LAYER SHEAR WILL BE RATHER STRONG AS A 50-60KT MID LEVEL JET NOSES ACROSS SOUTHERN MICHIGAN MONDAY EVENING IN THE BASE OF THE UPPER TROUGH. THIS WILL CREATE AN INCREASED RISK OF STRONG TO SEVERE THUNDERSTORMS. THE LIMITING FACTOR HOWEVER... AS USUALLY IS THE CASE THIS TIME OF YEAR... WILL BE THE AMOUNT OF INSTABILITY. THE NAM SOLUTION INDICATES AROUND 1500 J/KG SBCAPE. THIS HOWEVER SEEMS OVERDONE DUE TO UNREALISTICALLY HIGH SURFACE DEWPOINTS. THE GFS SOLUTION... WHICH BRINGS SURFACE DEWPOINTS OF LOWER 60S INTO SE MICHIGAN BY MONDAY EVENING... ONLY HAS A FEW HUNDRED J/KG OF CAPE. CONVECTIVE DEBRIS FROM UPSTREAM MCS ACTIVITY SUN NIGHT MAY ALSO LIMIT THE AMOUNT OF HEATING ON MONDAY. GIVEN THE SHEAR THOUGH... WILL STILL RETAIN THE POTENTIAL FOR STRONG TO SEVERE STORMS IN THE HWO. THE GFS...WRFXX AND UKMET SOLUTIONS INDICATE THE STRONGEST INSTABILITY WILL RESIDE SOUTH OF THE STATE. THESE SOLUTIONS ACTUALLY INDICATE VERY LITTLE QPF OVER SE MICHIGAN AS STRONG CONVECTION DEVELOPS OVER IL AND IN... INTERCEPTING SOME OF THE MOISTURE TRANSPORT INTO SE MICHIGAN. FOR THIS REASON... WILL KEEP POPS IN THE LOW CHANCE CATEGORY AT THIS TIME. RIDGING IS STILL EXPECTED TO BUILD BACK INTO THE REGION BY MIDWEEK... PROVIDING DRY CONDITIONS. AN UPPER LOW THAT DEVELOPS OFF THE COAST OF CALIFORNIA EARLY IN THE WEEK IS EXPECTED TO LIFT INTO THE GREAT LAKES REGION BY THE END OF THE WEEK... SHEARING OUT QUITE A BIT AS IT ENCOUNTERS THE STRONG RIDGE OVER THE CENTRAL US. BASED ON THE 12Z GFS AND WRFXX... WILL RETAIN A CHANCE OF CONVECTION LATE IN THE WEEK. THE EUROPEAN AND CANADIAN SOLUTIONS HOWEVER ARE STILL MORE AMPLIFIED WITH AN UPPER TROUGH THAT DEVELOPS OVER WESTERN CANADIAN AND THE NW US BY THE END OF THE WEEK AND THUS HAVE HIGHER HEIGHTS OVER THE EASTERN US. THIS MAY CAUSE THE BULK OF THE SHORT WAVE ENERGY TO PASS NORTH OF SE MICHIGAN. GIVEN THE ABOVE NORMAL HEIGHTS EXPECTED OVER THE EASTERN US THROUGH THE END OF THE WEEK... WILL CONTINUE TO FORECAST ABOVE NORMAL TEMPS WED THROUGH SAT. && .AVIATION... ISSUED AT 120 PM ACARS SOUNDINGS SHOW LOW LEVELS NEARLY SATURATED WITH PLENTY OF MOISTURE TRAPPED BELOW 700MB SUBSIDENCE INVERSION. 12Z RUC/NAM HAVE BEEN TOO AGGRESSIVE DRYING OUT THE COLUMN ACROSS SOUTHEAST MICHIGAN...TOO FAST BUILDING THE SURFACE HIGH ACROSS THE REGION WHERE PERSISTENT WEAK CYCLONIC FLOW STILL LINGERS. DTX RADAR STILL SHOWS WEAK ECHOES STREAMING OFF SOUTHERN LAKE HURON. CIGS HAVE SLOWLY CLIMBED OUT OF IFR/MVFR...WITH A NUMBER OF STATIONS ACROSS THE CWA PREDOMINATELY VFR. MBS CLEARED OUT EARLY THIS MORNING...BUT THAT IS AS FAR AS THE CLEARING LINE HAS MADE IT. CU CONTINUES FILL IN ACROSS THE NORTHERN CWA. ELSEWHERE FNT/DTW/DET ARE VFR AS OF 17Z...BUT MVFR STILL POSSIBLE AT DTW/DET FOR A COUPLE MORE HOURS WITH LOWER CIGS EXPECTED IN LIGHT DRIZZLE/RAIN SHOWERS STILL DEVELOPING IN NORTHEAST FLOW OFF LAKE HURON. OTHERWISE EXPECT CLOUDS TO CLEAR OUT THIS EVENING...WITH NEARLY CALM WINDS UNDER THE SURFACE HIGH. WITH RECENT PRECIP AND LINGERING LOW-LEVEL MOISTURE...COULD SEE SOME FOG TONIGHT. KEPT PREDOMINATE MVFR MENTION AT ALL THE TAF SITES AFTER MIDNIGHT. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BRAVENDER LONG TERM....CONSIDINE AVIATION...BRAVENDER mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 120 PM EDT SAT SEP 17 2005 .AVIATION... ACARS SOUNDINGS SHOW LOW LEVELS NEARLY SATURATED WITH PLENTY OF MOISTURE TRAPPED BELOW 700MB SUBSIDENCE INVERSION. 12Z RUC/NAM HAVE BEEN TOO AGGRESSIVE DRYING OUT THE COLUMN ACROSS SOUTHEAST MICHIGAN...TOO FAST BUILDING THE SURFACE HIGH ACROSS THE REGION WHERE PERSISTENT WEAK CYCLONIC FLOW STILL LINGERS. DTX RADAR STILL SHOWS WEAK ECHOES STREAMING OFF SOUTHERN LAKE HURON. CIGS HAVE SLOWLY CLIMBED OUT OF IFR/MVFR...WITH A NUMBER OF STATIONS ACROSS THE CWA PREDOMINATELY VFR. MBS CLEARED OUT EARLY THIS MORNING...BUT THAT IS AS FAR AS THE CLEARING LINE HAS MADE IT. CU CONTINUES FILL IN ACROSS THE NORTHERN CWA. ELSEWHERE FNT/DTW/DET ARE VFR AS OF 17Z...BUT MVFR STILL POSSIBLE AT DTW/DET FOR A COUPLE MORE HOURS WITH LOWER CIGS EXPECTED IN LIGHT DRIZZLE/RAIN SHOWERS STILL DEVELOPING IN NORTHEAST FLOW OFF LAKE HURON. OTHERWISE EXPECT CLOUDS TO CLEAR OUT THIS EVENING...WITH NEARLY CALM WINDS UNDER THE SURFACE HIGH. WITH RECENT PRECIP AND LINGERING LOW-LEVEL MOISTURE...COULD SEE SOME FOG TONIGHT. KEPT PREDOMINATE MVFR MENTION AT ALL THE TAF SITES AFTER MIDNIGHT. && .UPDATE...1111 AM EDT SAT SEP 17 2005 WEAKLY CYCLONIC LOW-LEVEL FLOW HAS BEEN MORE PERSISTENT ACROSS SOUTHEAST MICHIGAN...WITH SURFACE HIGH FROM LAKE MICHIGAN TO NORTHERN LAKE HURON SLOWER TO BUILD DOWN ACROSS THE STATE. LINGERING LOW-LEVEL MOISTURE AND WEAK LIFT HAD LED TO A PERSISTENT LOW CLOUD DECK. ISOLATED ECHOES ARE STILL APPARENT DEVELOPING OFF THE SOUTHERN END OF LAKE HURON. 14Z-15Z ACARS SOUNDINGS NEAR DTW SHOW A SOLID NEARLY SATURATED LAYER FROM THE SURFACE THROUGH 800MB. 12Z RUC ALSO SHOWS MOISTURE HOLDING ON FOR LONGER...WITH A CONTINUED NORTHEASTERLY CYCLONIC GRADIENT THROUGH MID AFTERNOON. WILL UPDATE TO CARRY ISOLATED LIGHT SHOWERS FOR A FEW MORE HOURS INTO THE EARLY AFTERNOON...AND ALSO HOLD ONTO CLOUDS LONGER THROUGH THE DAY. FAR NORTHWEST CWA CLEARED OUT BY SUNRISE...BUT THE BACK EDGE OF THE CLOUDS HAS MADE LITTLE SOUTHEASTWARD PROGRESS SINCE THEN. IN FACT... LATEST VIS SATELLITE SHOWS SOME CU BEGINNING TO FILL IN ALONG THE BACK EDGE. EXPECT CEILING HEIGHTS TO CONTINUE TO RISE AS THEY HAVE DONE THROUGH THE MORNING...BUT CLOUDS WILL STICK AROUND LONGER THROUGH THE AFTERNOON. WITH LIMITED INSOLATION...WILL ALSO NEED TO TRIM HIGHS ACROSS THE SOUTHEAST CWA BACK A DEGREE OR TWO. && .SHORT TERM...SATURDAY AND SATURDAY NIGHT...ISSUED AT 338 AM EDT STRATUS WILL BE A BIT SLOW TO ERODE THIS MORNING...BUT DO EXPECT A FAIR AMOUNT OF SUNSHINE ACROSS SOUTHEAST MICHIGAN BY THIS AFTERNOON. IN FACT...WOULD EXPECT THE SUN TO BREAK OUT IN THE SAGINAW AND GENESEE VALLEYS BY MID MORNING. THIS WILL LEAD TO A MILD DAY WITH HIGHS BACK INTO THE 70S. WILL PLAY THE FORECAST SOMEWHAT CONSERVATIVELY GIVEN THE MORNING CLOUD COVER. BASICALLY EXPECT THE NORTHWEST CWA TO APPROACH GUIDANCE VALUES IN THE MID/UPPER 70S WITH AREAS FURTHER SOUTHEAST MORE LIKELY TO STAY BELOW GUIDANCE AND HOLD IN THE LOWER 70S...WHERE CLOUD COVER WILL TAKE A FEW EXTRA HOURS TO BREAK UP. COOL...NORTHEAST FLOW WILL NOT HELP IN A QUICK RECOVERY THIS AFTERNOON. BASICALLY CLEAR SKIES BY EVENING AND OVERNIGHT. WITH HIGH PRESSURE SETTLING THROUGH THE REGION...WINDS WILL BE LIGHT. WILL MAINTAIN A RELATIVELY COOL FORECAST...IN/AROUND 50 IN MOST LOCATIONS. INTERIOR METRO DETROIT AND LOCATIONS IMMEDIATELY ADJACENT TO THE RELATIVE WARMTH OF THE GREAT LAKES WILL BE THE EXCEPTIONS...HOLDING MORE IN THE MID 50S. && .LONG TERM...SUNDAY THROUGH FRIDAY...ISSUED AT 338 AM EDT A VERY CHALLENGING FORECAST AS WE WILL FOLLOW THE GFS/ECMWF/CANADIAN ...WHICH LEADS TOWARD MORE AMPLIFICATION AND THE CHANCE FOR SEVERE WEATHER ON MONDAY. STARTING WITH SUNDAY...WEAKENING SHORT WAVE TROF APPROACHING AND SOME Q-VECTOR CONVERGENCE MOVES ACROSS THE STATE YET LOWER LEVELS ARE QUITE DRY WITH AOA 1020MB SURFACE HIGH IN PLACE. MAIN SURFACE CONVERGENCE IS ALONG THE COLD FRONT THAT WILL LIKELY REMAIN ACROSS THE STRAIGHTS AS PACIFIC ENERGY (SEEN IN THE H2O VAPOR LOOP THIS MORNING ACROSS THE PACIFIC NORTHWEST) EJECTS INTO THE CENTRAL PLAINS AND MID LEVEL FLOW SHOULD BECOME PARALLEL TO THE SURFACE TO IMPEDE FORWARD PROPAGATION. SO A DRY AND WARMER DAY WITH TEMPERATURES COMING CLOSE TO THE 80F DEGREE MARK. UPSTREAM ACTIVITY WILL BE THE KEY TO OUR SEVERE WEATHER POTENTIAL ON MONDAY. AFTER CLOSE COLLABORATION WITH SPC THIS MORNING...THE APPROACH OF PACIFIC SYSTEM AND NOCTURNAL LOW LEVEL JET FORCING WILL LIKELY RESULT IN ONE OR MORE MCS/S ACROSS THE MISSISSIPPI RIVER VALLEY. HOWEVER...WE ARE EXPECTING AN EXTENSIVE SUBTROPICAL RIDGE TO DEVELOP ACROSS THE SOUTHERN CONUS WHICH IN TURN WILL TIGHTEN THE THERMAL FIELDS AND MIGHT DAMPEN THE WAVE SOMEWHAT AS IT APPROACHES THE STATE MONDAY. THIS SETS UP A PROBLEM FOR THE SOUTHERN HALF OF THE CWA AS A MODEL BLEND SUGGESTS A LITTLE SLOWER TIMING AND IF WE RECEIVE ADDITIONAL INSOLATION ALONG WITH LOW LEVEL MOISTURE ADVANCING NORTHWARD...PLENTY OF SHEAR EXPECTED FOR ORGANIZED CONVECTION ESPECIALLY IF WARM FRONTAL/DEWPOINT BOUNDARY BECOMES QUASI-STATIONARY ACROSS THE CWA. STILL PLENTY OF TIME TO MONITOR AND WE INTEND TO HIGHLIGHT THIS WITHIN THE HWO (HAZARDOUS WEATHER OUTLOOK) THIS MORNING. WE WILL RAISE TEMPERATURES A FEW DEGREES FROM CURRENT FORECAST WITH THE ANTICIPATION OF ADDITIONAL SUNSHINE AND WARMING COLUMN. WE WILL ALSO RETAIN THE CHANCE FOR CONVECTION UNTIL TIMING BECOMES MORE APPARENT (SEE SWODY3 FOR ADDITIONAL DETAILS). FRONTAL BOUNDARY TIMING SEEMS TO CLEAR THE CWA MONDAY NIGHT YET THE CANADIAN IS THE SLOWEST WITH THE GFS THE FASTEST. SO THE UKMET IS SOMEWHAT IN THE MIDDLE AND WE WILL KEEP THE CHANCE FOR ADDITIONAL CONVECTION OVERNIGHT AND BRING BACK THE CHANCES FOR LIGHT SHOWERS ON TUESDAY MORNING. THEN IMPRESSIVE SUBSIDENCE UNFOLDS WITH INCREASING AMOUNTS OF SUNSHINE AND 850MB TEMPS SUPPORT TEMPERATURES INTO THE MIDDLE 70S. THEN IT LOOKS FAIRLY QUIET (OUTSIDE OF TROPICAL ACTIVITY) THROUGH MID WEEK UNTIL ADDITIONAL PACIFIC ENERGY COMES ASHORE AS IT SEEMS WE GO THROUGH A REPEAT PERFORMANCE BY THURSDAY AND FRIDAY. THERE IS ENOUGH EVIDENCE TO BRING IN THE CHANCE FOR CONVECTION AT THIS TIME. THE ECMWF IS THE MOST EMPHATIC WITH ITS 850MB WARM THERMAL ADVECTION ON THURSDAY WITH THE DGEX SOMEWHAT IN LINE AND THE CANADIAN MORE DIFFUSE. EITHER WAY...THIS CHANGE IS IN AGREEMENT WITH COLLABORATION WITHIN NEIGHBORING OFFICES. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....BRAVENDER UPDATE.......BRAVENDER SHORT TERM...DG LONG TERM....BGM HTTP://WEATHER.GOV/DETROIT mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 304 PM CDT SAT SEP 17 2005 .SHORT TERM...TONIGHT THROUGH TUESDAY TWO MAIN AREAS OF PCPN CONT ACRS THE FA PER LOCAL 88D MOSAIC. NRN AREA /FM MOX TO JMR/ HAS BEEN STEADILY DECR IN AREAL COVERAGE AND INTENSITY...AS EXPECTED BY THE INCR COND PRES DEFICITS ON THE 310K SFC FM THE 12Z RUC. SRN AREA /FM NR FSD TO MKT/ HAS BEEN MORE PERSISTENT ON ITS NELY TRACK. THIS AREA SHUD CONT TO MOVE NEWRD INTO THE SRN THIRD TO HALF OF THE FA AS THE LOW LVL THETA-E ADVECTION MOVES NEWRD THIS EVE. A WEAKENING IN THE THETA-E ADVECTION WL CORRELATE WITH A GRADUAL DECR IN THE AREAL COVERAGE AND INTENSITY /ALREADY EVIDENT IN THE 88D TRENDS/ OF THE SHRA/TSRA AS THE NGT PROGRESSES. 19Z MSAS ANALYSES AND SFC OBS DEPICT THE SFC LO NR THE NE/SD BORDER WITH THE STNRY BNDRY EXTENDING TO NR INL. THIS BNDRY HAS MOVED VERY LITTLE DURING THE DAY...WHICH WILL RESULT IN INTERESTING WX TOMORROW AFTN AND EVE. THE FA SHUD SEE A BRIEF BREAK IN THE PCPN AS TODAY'S PCPN MOVES EWRD OVRNGT. BNDRY SHUD MAKE A LITTLE SWRD PROGRESS AS THE TROF APPROACHES TNGT...BUT MUCH OF THE FA WILL REMAIN IN THE WARM SECTOR TOMORROW AFTN AND EVE...WHICH COULD RESULT IN SOME SVR STORMS...MAINLY ACRS THE SRN HALF OF THE FA. 12Z NAM AND GFS DIFFER ON MANY OF THE SPECIFICS OF THE FROPA...WITH THE NAM TAKING A MORE AGGRESSIVE MOVEMENT...AND THE GFS FAVORING A MORE VIGOROUS SYSTEM. ATTM...BELIEVE THAT THE GFS SOLN IS MORE REASONABLE...CONSIDERING RECENT PERFORMANCE OF BOTH MODELS AND THE CURRENT SLOW MOVEMENT OF THE SYSTEM...SO HAVE LEANED THE FCST TOWARD THE SLOWER GFS. DURG THE AFTN...STEEP MID LEVEL LAPSE RATES...NEARING 8C/KM...AND AMPLE DEEP LAYER SHEAR /PER NAM AND GFS BUFR SOUNDINGS/ COULD SUPPORT SOME LARGE HAIL/DMG WIND PRODUCING SVR STORMS AHD OF THE MAIN BNDRY. THE MAJORITY OF THE TSRA...HOWEVER...WILL ACCOMPANY THE MAIN FRONTAL PASSAGE AND THE APPROACH OF H7 TROF LATE SUN AND INTO MON. INCR POPS INTO THE LIKELY CATEGORY IN A BAND THAT PROGRESSIVELY MOVES EWRD SUN NGT...FOLLOWING THE H7 OMEGA MAX...THE H8 THETA-E RIDGE...AND THE NOSE OF THE LLJ. HAVE ALSO LINGERED SHRA CHANCES ACRS MAINLY THE NRN TWO-THIRDS OF THE FA...DUE TO THE CHANCE FOR WRAP AROUND ON THE BACKSIDE OF THE SFC LO. HI PRES SETTLES INTO THE RGN MON NGT AND TUE...WHICH WL BRING CLEARING SKIES...DRY WX...AND REBOUNDING TEMPS. THANKS FOR THE COORDINATION FGF...DMX...AND ARX. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY WAA STARTS AGAIN ON WED AHEAD OF NEXT SHORT WAVE FCST TO SWING THRU CWA WED NIGHT INTO THU MORN. WAVE A BIT SLOWER THAN PREVIOUS RUNS SO HAVE PUSHED POP START TIME INTO WED AFT. WEAK FROPA THU WITH DRYING CONDITIONS. NEXT WAVE SWINGS THRU ZONES FRI INTO EARLY SAT SO ANOTHER ROUND OF SCT TSRA. FROPA LATE FRI NIGHT USHERS IN A TON OF CAA WHICH WILL DROP TEMPS SIGNIFICANTLY INTO SAT WHEN SIG UPPER LVL TROF AND WRAPAROUND CLDS WILL PUSH THRU. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ KAT/MARGRAF mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 205 PM CDT SAT SEP 17 2005 .DISCUSSION... SURFACE RIDGE WAS SHIFTING EAST OF THE AREA THIS AFTERNOON ALLOWING SOUTHEASTERLY FLOW TO RETURN. THIS FLOW HAD ADVECTED STRATO CUMULUS ACROSS SOUTH CENTRAL MISSOURI. FARTHER WEST A LEE SIDE TROUGH WAS DEVELOPING ACROSS THE HIGH PLAINS IN ADVANCE OF AN UPPER TROUGH THAT ACROSS THE WEST. WATER VAPOR AND RUC MODEL ANALYSIS DEPICT A STRONG UPPER JET STRETCHING FROM THE DESERT SOUTHWEST INTO THE MIDWEST. A FAIRLY ACTIVE PATTERN WILL SET UP THE NEXT COUPLE OF DAYS. STRONG WARM AIR ADVECTION AND MOISTURE TRANSPORT WILL DEVELOP TONIGHT ACROSS THE SOUTHERN PLAINS. CONVECTION IS EXPECTED TO IGNITE ACROSS EASTERN KANSAS AND NORTHEAST OKLAHOMA. MODERATELY STRONG WESTERLIES WILL YIELD DEEP 0-6KM SHEAR VALUES OF 40 TO 50 KTS. THIS COMBINED WITH CONSIDERABLE ELEVATED INSTABILITY WILL SUPPORT STRONG TO SEVERE THUNDERSTORMS. THE ACTIVITY WILL SPREAD INTO EXTREME SOUTHEAST KANSAS AND FAR SOUTHWEST MISSOURI DURING THE PREDAWN HOURS TO AROUND SUNRISE. STRONG MOISTURE TRANSPORT AND CONVERGENCE WILL ALSO SUPPORT HEAVY RAINFALL RATES. CONVECTIVE CLUSTERS OR PERHAPS A SMALL CONVECTIVE COMPLEX WILL SPREAD INTO SOUTHWEST MISSOURI SUNDAY MORNING AS THE LOW LEVEL JET VEERS. 850 MB TEMPERATURES ARE PROGGED TO RISE SEVERAL DEGREES AS DEVELOPING WARM FRONT LIFTS NORTH. TEMPERATURES SHOULD RECOVER NICELY ACROSS SOUTHWEST PORTIONS OF THE FORECAST AREA...BUT CLOUD DEBRIS AND LINGERING CONVECTION MAY HOLD TEMPERATURES DOWN A BIT ACROSS CENTRAL AND SOUTH CENTRAL MISSOURI. A SIMILAR SCENARIO WILL LIKELY SET UP SOMEWHERE IN THE REGION SUNDAY NIGHT. A FRONT IS PROGGED TO EXTEND EAST TO WEST ACROSS CENTRAL KANSAS AND MISSOURI. A LOW LEVEL JET WILL AGAIN STRENGTHEN AND INTERSECT THIS BOUNDARY. ACTIVITY MAY BE FOCUSED A LITTLE FARTHER NORTH AND RAIN CHANCES HAVE ADJUSTED ACCORDINGLY. THE MEANDERING BOUNDARY WILL LIKELY LIFT NORTH AWAY FROM THE AREA AS WE HEAD INTO MID AND LATE WEEK AS THE UPPER RIDGE TO OUR SOUTH EXPANDS NORTHWARD. THIS WILL RESULT IN ABOVE NORMAL TEMPERATURES AND FAIRLY HUMID CONDITIONS. && .AVIATION... VFR CONDITIONS WILL PREVAIL THROUGH MUCH OF TONIGHT OVER THE KJLN AND KSGF TERMINAL SITES. AN INCREASING LOW-LEVEL JET AND CORRESPONDING MOISTURE TRANSPORT MAY BRING A CONVECTIVE COMPLEX INTO SOUTHWEST MISSOURI TOWARD DAWN ON SUNDAY. DUE TO THE UNCERTAINTY OF THE EXTENT AND TIMING OF THE STORMS...ONLY ADDED BKN030CB AFTER 11Z TO THE RECENTLY ISSUED TAFS. LATER SHIFTS WILL LIKELY INTRODUCE SOME THUNDER ONCE CONVECTION DEVELOPS ACROSS THE PLAINS TONIGHT. SAW && SGF WATCHES/WARNINGS/ADVISORIES... .MO...NONE. .KS...NONE. $$ WFO SGF mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LUBBOCK TX 1130 AM CDT SAT SEP 17 2005 .UPDATE... AIRMASS IS QUITE WARM AND HUMID ACROSS THE FORECAST AREA LATE THIS MORNING. LOWS CLOUDS HAD DISSIPATED OVER ALL BUT THE NORTHERN ROLLING PLAINS...AND THOSE CLOUDS SHOULD DISSIPATE BEFORE 18Z OR SO. MORNING RAOBS FROM AMA/MAF INDICATED VERY STEEP INVERSIONS...PARTICULARLY AMA...SUGGESTING TEMPERATURES WILL CONTINUE TO WARM QUITE QUICKLY INTO THE MID AND UPPER 80S BEFORE THE RATE OF CHANGE SLOWS. SOUNDINGS ALSO INDICATED QUITE WARM MID LEVEL TEMPERATURES. LATEST NAM RUN CONTINUES TO SUGGEST SOME CONVECTION MAY FORM OVER WESTERN SECTIONS LATE THIS AFTERNOON. THINK THAT MID LEVEL CAPPING WILL HAVE SOMETHING TO SAY ABOUT THAT...BUT IF STORMS DO DEVELOP A FEW COULD BE SEVERE GIVEN HIGH INSTABILITY AND DECENT WIND PROFILE. LATEST RUC SUGGESTS CONVECTION WILL FIRE OVER HIGHER TERRAIN IN NEW MEXICO AND THEN ADVECT INTO WESTERN SECTIONS EARLY THIS EVENING. IF EITHER SCENARIO PANS OUT WE DOUBT COVERAGE WILL BE THAT GREAT AND SHOULD BE ON THE DECREASE WITH SUNSET. GRIDS ALREADY HAVE ALL OF THIS WELL IN HAND. && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 13 tx