AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 359 AM MDT MON SEP 3 2007 .SHORT TERM... (TDA AND TNGT) MAIN TSTM COVERAGE SHOULD BE OVER THE MOUNTAINS WITH ABOVE AVERAGE TEMPERATURES FOR THE NEXT 24 HOURS. CURRENTLY...WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES HAD HIGH PRESSURE CENTERED OVER THE SRN CA/SRN NV WITH SEVERAL SHORTWAVE TROUGHS ROTATING THROUGH THE HIGH/S ERN HALF ACROSS THE GREAT BASIN AND CNTRL/SRN ROCKIES. ALSO...THERE WAS AN ERN WAVE CYCLONIC SHEAR AXIS ACROSS WRN TX...AND NEARLY STATIONARY OR SLOWLY DRIFTING NWWD. MUCH OF YDA/S CONVECTIVE DEBRIS CLOUDS WERE DISSIPATING AFTER MIDNIGHT. SFC-LOW LEVEL MOISTURE STILL RESPECTABLE WITH DEW POINTS IN THE 20S-NEAR 50 IN THE MOUNTAINS AND AROUND 50 SERN CO. TDA AND TNGT...WRF AND GFS HAVE GOOD CONTINUITY OF DEVELOPING SHRA/TSRA OVER THE MOUNTAINS/HIGH VALLEYS THIS AFTN/EVE AND THEN DISSIPATING SHORTLY BEFORE MIDNIGHT. THE CONVECTIVE DEBRIS CLOUDS SHOULD DISSIPATE AFTER MIDNIGHT. HARD TO ARGUE THIS SCENARIO. PRECIPITATION MOTION WOULD BE S-SWLY...SO IT WILL BE TOUGH FOR PRECIPITATION TO MOVE OFF THE MOUNTAINS INTO THE I-25 CORRIDOR/SERN CO PLAINS. WRF/GFS KEEP THE SERN CO PLAINS RELATIVELY DRY THIS AFTN/EVE...AS SBCAPES VALUES ARE PROGGED TO BE AROUND 0 J/KG GIVEN THE WARMING/H5 DRYING ALOFT AND SFC DEW POINTS DECREASING. THE GREATEST INSTABILITY...ALBEIT WEAK-MARGINALLY MODERATE...SHOULD BE OVER THE MOUNTAINS/HIGH VALLEYS. THE MAIN TSTM IMPACT WILL BE HAIL UP TO 1/4 INCH AND MODERATE-HEAVY RAIN GIVEN FREEZING/WET BULB ZERO HEIGHTS OF 14K-16K FT MSL OVER THE MOUNTAINS AND H7-H5 SPECIFIC HUMIDITY VALUES OF 5-6 G/KG. WIND GUSTS OF 30-40 MPH WILL BE POSSIBLE NEAR STORMS ACROSS THE LOWER MOUNTAIN ELEVATIONS. MAXIMUM TEMPERATURES WILL...AGAIN...BE A CATEGORY OR TWO ABOVE AVERAGE READINGS FOR EARLY SEP WITH 90S ANTICIPATED ACROSS THE SERN CO PLAINS. WENT WITH A 50-50 BLEND OF MAV/MET GUIDANCE. METZE .LONG TERM... (TUESDAY THROUGH SUNDAY) FOR TUESDAY AND WEDNESDAY...CWFA STILL UNDER INFLUENCE OF UPPER RIDGE WHILE UPPER STORM SYSTEM DIGS INTO NORTHERN CALIFORNIA TUESDAY AND THEN INTO NORTHERN UTAH BY 00Z THURSDAY. DURING THURSDAY...THIS UPPER LEVEL DISTURBANCE WEAKENS AS IT MOVES ACROSS NORTHERN COLORADO. CWFA IS THEN IN A DRIER NORTHWEST FLOW ALOFT PATTERN FROM THURSDAY INTO FRIDAY BEFORE MOISTURE LEVELS ATTEMPT TO INCREASE FROM FRIDAY NIGHT INTO THE WEEKEND THANKS IN PART TO THE SURFACE LEE TROUGH OF TUESDAY INTO FRIDAY MORNING GIVING WAY TO A STRENGTHENING SURFACE HIGH PRESSURE REGIME FROM FRIDAY NIGHT INTO THE WEEKEND. ISOLATED TO SCATTERED POPS SHOULD SUFFICE FROM TUESDAY INTO THURSDAY...WITH GENERALLY NIL POPS FRIDAY GIVING WAY TO ISOLATED POPS FROM FRIDAY NIGHT INTO THE WEEKEND. STILL PROJECT ABOVE CLIMATOLOGICAL AVERAGE TEMPERATURES TO CONTINUE FROM TUESDAY INTO AT LEAST THURSDAY...WITH TEMPERATURES THEN DROPPING TO VALUES AT OR BELOW SEASONAL AVERAGES BY SATURDAY. AT THIS POINT...WARMEST TEMPERATURES FOR THE LONG TERM SHOULD OCCUR THIS TUESDAY AND WEDNESDAY WITH COOLEST TEMPERATURES NOTED SATURDAY. && .AVIATION... ISOLD-SCT SHRA/TSRA WILL BE LIKELY OVER THE MOUNTAINS/HIGH VALLEYS BETWEEN 18Z/03 - 06Z/04 INCLUDING NEAR THE KALS TERMINAL POINT. KCOS AND KPUB WILL HAVE VERY LOW PROBABILITIES FOR SHRA/TSRA THIS AFTN/EVE. PLAN TO GO WITH VICINITY TSTMS IN KALS TAFS AND KEEP OUT OF THE KCOS/KPUB. ANY TSTM WILL HAVE ERRATIC WINDS...SMALL HAIL...MVFR-VFR CEILINGS...AND POSSIBLY MODERATE- HEAVY RAIN ACROSS THE MOUNTAINS/HIGH VALLEYS. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 345 AM EDT MON SEP 3 2007 .SYNOPSIS...SURFACE LOW EVIDENT ON SATELLITE APPROXIMATELY 150 MI EAST OF JACKSONVILLE OVER THE ATLANTIC WATERS. HIGHER INSTABILITY OVER THE WATERS (WARMER TEMPS AND HIGHER DEW POINTS IN ADDITION TO SUPPORT FROM THE LOW) ALLOW FOR CONVECTION TO CONTINUE WHILE SHOWER ACTIVITY HAS GENERALLY DIMINISHED OVER LAND. SURFACE OBSERVATIONS SHOW DRIER AIR FILTERING BEHIND THE LOW WITH DEW POINTS IN THE 50S AND LOWER 60S ACROSS THE CAROLINAS. .FOR TODAY...MODELS HAVE SOME DEGREE OF DISAGREEMENT OVER THE EXACT DEVELOPMENT OF THE SURFACE LOW. NAM AND THE RUC SEEM TO HAVE THE BEST HANDLE ON THE CURRENT SITUATION...SO HAVE LEANED TOWARDS THIS SOLUTION. UPPER DIVERGENCE AND THETA-E ADVECTION WILL BE GREATEST OVER THE FLORIDA COASTAL WATERS AND FLORIDA COAST...SO EXPECT THE BEST CHANCE OF PRECIPITATION IN THESE AREAS. PWAT WILL DECREASE ACROSS NORTHERN COUNTIES OF THE FORECAST AREA...WHILE TROPICAL AIRMASS...PWATS ABOVE 2 INCHES...AND WEAK STEERING FLOW WILL LEAD TO HEAVY RAIN POTENTIAL IN AFOREMENTIONED FLORIDA AREAS. PRECIPITATION LOADING MAY ENHANCE DOWNBURSTS WITH ANY THUNDERSTORMS THAT CAN DEVELOP. .FOR TOMORROW...MODELS SHOW THAT A JET AXIS WILL DIG AROUND THE UPPER HIGH AND DEEPEN THE SURFACE LOW OVER THE ATLANTIC. DRIER AIR WILL THEN WRAP AROUND THE WESTERN PERIPHERY OF THIS LOW...LEADING TO DECREASING CHANCES OF PRECIPITATION. .LONG TERM...UNCERTAINTY IN THE EXTENDED CONTINUES...AND IS DEPENDENT UPON THE DEVELOPMENT AND PLACEMENT OF THE SURFACE LOW. THE GENERAL AGREEMENT IS THAT DRIER AIR AND LOWER CHANCES OF PRECIPITATION WILL CONTINUE THROUGH MID WEEK AS THE LOW SLOWLY DRIFTS EASTWARD AND LINGERS WITH NO WELL DEFINED SYSTEM TO KICK IT OUT. BY THE END OF THE WEEK THE LOW WILL SLOWLY DRIFT BACK TOWARDS FLORIDA WITH INCREASING MOISTURE AND DYNAMIC SUPPORT FOR INCREASED PRECIPITATION CHANCES. TEMPERATURES WILL BE WITHIN A DEGREE OR TWO OF CLIMATOLOGY THROUGHOUT THE FORECAST PERIOD. && .AVIATION...MOST TAF SITES ARE REPORTING CEILINGS BELOW 500 FT AND THIS IS IN RESPONSE TO CLOSE PROXIMITY TO SURFACE LOW CURRENTLY POSITIONED OFFSHORE JACKSONVILLE. LIFR/POSSIBLY LIFR CONDITIONS WILL PERSIST THOUGH AROUND 13Z...WITH MAINLY VFR CONDITIONS THEREAFTER WHEN DAYTIME HEATING ERODES LOW CLOUD DECKS. WILL CONTINUE VCSH WORDING TODAY...EXCEPT WILL INCLUDE TEMPO TSRA AFTER 17Z FOR SITE KGNV WHERE SEA-BREEZE COLLISION WILL LIKELY OCCUR COUPLED WITH FAVORABLE DYNAMICS ALOFT. && .MARINE...SURFACE LOW IS CURRENTLY POSITIONED WELL OFFSHORE JACKSONVILLE AND THIS FEATURE IS FORECAST TO MEANDER THROUGH MID-WEEK WITH POSSIBLE MOVEMENT TOWARDS THE NORTH FLORIDA COASTLINE LATE THIS WEEK. SCEC CONDITIONS WILL LIKELY OVERSPREAD THE COASTAL WATERS DURING THE DAY AS SURGE OF NORTHERLY WINDS WORK DOWN THE THE LOCAL COASTLINE...WITH MODERATE NORTHERLY WINDS LIKELY PERSISTING THROUGH AT LEAST FRIDAY. THE INTENSITY OF THIS LOW PRESSURE SYSTEM IS STILL UNCERTAIN...AS WELL AS HOW HIGH THE LOCAL WINDS AND SEAS WILL GET...WITH POSSIBILITY OF SCA CONDITIONS ESTABLISHING IN THE LOCAL WATERS. && .PRELIMINARY POINT TEMPS/POPS... AMG 89 67 91 68 / 20 10 10 0 SSI 85 74 87 76 / 40 20 20 0 JAX 87 71 89 73 / 50 30 30 0 SGJ 86 74 87 76 / 60 40 40 0 GNV 89 71 90 71 / 50 40 40 20 OCF 90 71 90 71 / 50 40 40 20 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ HURLBUT/ZAPPE fl AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PEACHTREE CITY GA 530 AM EDT MON SEP 3 2007 .SHORT TERM /TODAY THROUGH WEDNESDAY/... EASTERLY WINDS WILL CONTINUE TO ADVECT DRY AIR INTO THE CWA TODAY. WITH UPPER RIDGE BUILDING OVER THE SOUTHEAST THROUGH THE REMAINDER OF THE SHORT TERM...LIFTED INDEX VALUES REMAINING POSITIVE ACROSS THE CWA...AND GUIDANCE POPS LESS THAN 10 PERCENT...A DRY FORECAST LOOKS REASONABLE. AFTERNOON TEMPERATURES SHOULD BE WARMING BACK INTO THE LOW AND MID 90S DURING THE NEXT COUPLE OF DAYS. SOME MORNING CLOUDINESS ASSOCIATED WITH THE EASTERLY FLOW SHOULD DISSIPATE DURING THE DAY. .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... CENTER OF UPPER RIDGE SLIDING TO THE ATLANTIC COAST BY THE MIDDLE OF THE WEEK. THIS SHOULD GIVE A RETURN OF GULF MOISTURE TO THE SOUTHEAST AND A BETTER CHANCE FOR DIURNAL CONVECTION. HAVE KEPT THE FORECAST DRY UNTIL FRIDAY AND FOR NOW THIS STILL LOOKS OKAY. LOW CHANCE OR SLIGHT CHANCE FOR THE REMAINDER OF THE EXTENDED LOOKS REASONABLE AS UPPER FLOW BECOMES MORE SOUTHWEST. && .AVIATION... HIGH PRESSURE OFF THE MID-ATLANTIC WILL SLOWLY MOVE INLAND WITH DRIER AIR MOVING INTO THE AREA. SOME MID-LEVEL MOISTURE MAY REMAIN BUT HARDLY ENOUGH TO NOTE IN THE TAFS. STILL HAVE AN AREA OF CEILINGS FROM 5-9KFT FROM COLUMBUS TO MACON AT THIS TIME...PICKED UP WELL BY THE NAM AND RUC EARLIER TONIGHT. GFS WANTS TO SWING THE WINDS AROUND TO THE NORTHWEST EARLY TUESDAY MORNING BUT NAM HASN`T QUITE PICKED UP ON THIS YET...FOR NOW WILL KEEP NORTHEASTERLY TREND. DO NOT EXPECT MUCH IN THE WAY OF LOWERED VISIBILITIES TUESDAY MORNING WITH THE DRIER AIR IN PLACE ALTHOUGH MAY SEE SOME BRIEF MVFR FOG/HAZE AT THE TYPICAL SITES. OTHERWISE...A FAIRLY BENIGN FORECAST. && .PRELIMINARY POINT TEMPS/POPS... ATHENS 90 62 94 65 93 / 0 0 0 5 5 ATLANTA 89 68 92 70 89 / 0 0 0 5 5 BLAIRSVILLE 89 60 91 59 90 / 0 5 0 10 5 CARTERSVILLE 88 59 92 62 93 / 0 5 0 5 5 COLUMBUS 92 65 94 70 94 / 0 0 0 5 5 GAINESVILLE 89 66 91 67 90 / 0 5 0 10 5 MACON 91 61 94 66 95 / 0 0 0 5 5 ROME 92 62 94 66 94 / 0 5 5 10 5 PEACHTREE CITY 90 59 92 60 91 / 0 0 0 5 5 VIDALIA 89 69 93 69 94 / 10 0 0 5 5 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 41/TDP ga AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SHREVEPORT LA 939 PM CDT MON SEP 3 2007 .DISCUSSION... CONVECTION CONTINUES TO PERSIST ACROSS EXTREME SE OK...AND ADJACENT SW AR...MAINLY THE NE EXTREMES OF OUR SW AR COUNTIES...ALONG A WEAK INVERTED MID LEVEL TROUGH AXIS THAT THE 18Z PROGS AND NEW RUC HAS PICKED UP ON...THAT EXTENDS FROM SE OK...INTO SCNTRL AR/EXTREME NE LA...AND INTO SCNTRL MS...THAT HAS BECOME SANDWICHED BETWEEN THE MID LEVEL RIDGE OVER THE TN/OHIO VALLEYS...AND BROAD SHORTWAVE TROUGH AXIS OVER FAR W TX. RECENT RADAR LOOPS SHOW RENEWED DEVELOPMENT ALONG THIS TROUGH AXIS...AND POSSIBLE A WEAK OUTFLOW BOUNDARY THAT MAY BE SLOWLY DRIFTING SW INTO N MCCURTAIN COUNTY...AND ADJACENT SW AR...PER RECENT SFC OBS FROM MT HERMAN AND BROKEN BOW OK...DEQ AND TXK AR. HOWEVER...IR SATELLITE LOOPS INDICATE THAT CLOUD TOPS ARE GRADUALLY WARMING...MEANING THAT CONVECTION IS SLOWLY WEAKENING AS WELL. HOWEVER...IN THE EVENING ZONE UPDATE...HAVE BUMPED UP POPS FOR THESE AREAS TO LIKELY UNTIL MIDNIGHT...WITH CONVECTION DIMINISHING AFTERWARDS. ELSEWHERE...SCATTERED CONVECTION HAS WEAKENED ALL-TOGETHER...WITH BLOB OF RAIN OVER NE TX...STRETCHING W OF A CANTON TO ATHENS LINE... POSSIBLY REACHING PORTIONS OF WOOD AND SMITH COUNTIES BEFORE DIMINISHING BY MIDNIGHT AS WELL. CAN/T RULE OUT ADDITIONAL SHOWER REDEVELOPMENT OVERNIGHT AS RICH GULF INFLOW AND SUBTROPICAL MOISTURE PLUME FROM TS HENRIETTE S OF BAJA CONTINUES TO ADVANCE NE ACROSS TX/OK AHEAD OF STATIONARY TROUGH/SHEAR AXIS OVER FAR W TX. PATCHY FOG MAY ALSO FORM LATE WHERE EARLIER RAINS FELL...BUT EXTENSIVE AC/CIRROSTRATUS SHOULD LIMIT WIDESPREAD DEVELOPMENT...THUS NOT ENOUGH TO MENTION IN THE ZONES ATTM. ALSO MADE SOME MINOR ADJUSTMENTS TO MIN TEMPS PER CURRENT TRENDS...BUT OTHERWISE...FORECAST IS IN GOOD SHAPE. UPDATE ALREADY OUT. 15 && .AVIATION... DOPPLER RADAR INDICATED DECREASING SHOWERS AND THUNDERSTORMS ACROSS THE FOUR STATE REGION DUE TO LOSS OF AFTERNOON HEATING. WITH LIGHT WINDS...A WET GROUND FROM RECENT RAINS...AND PLENTY OF GULF MOISTURE FEEDING INTO THE AREA WILL EXPECT TO SEE FOG/MIST AND POSSIBLY LOW STRATUS CEILINGS THROUGH THE REMAINING HOURS OF DARKNESS. MOST DENSE FOG AND LOWER CEILINGS WILL BE AROUND 04/10Z TO 04/14Z TUESDAY WITH SURFACE VISIBILITIES OF 1 TO 3 STATUTE MILES MOST COMMON AND CEILINGS AT FL20 DOWN TO FL10. SOME LOWER CEILINGS BELOW FL10 POSSIBLE ACROSS E TX AND THE IMMEDIATE ADJACENT SECTIONS OF SW OK...SW AR...AND S CENTRAL AR INTO NE LA WHERE MOST OF THE RAINFALL FELL ON LABOR DAY. RAIN AND THUNDERSTORMS EXPECTED TO RETURN DURING THE DAY TUESDAY AS THE TEMPERATURES WARM AND UPPER DISTURBANCES ENHANCE DEVELOP FROM 04/18Z INTO THE LATE AFTERNOON AND CONTINUE INTO THE EVENING. /06/ && .PRELIMINARY POINT TEMPS/POPS... SHV 74 89 72 86 / 20 40 40 60 MLU 71 90 72 88 / 40 50 40 50 DEQ 70 89 70 84 / 60 50 50 70 TXK 71 89 71 85 / 40 50 50 70 ELD 69 87 71 86 / 60 30 40 50 TYR 71 85 72 85 / 40 50 50 70 GGG 71 88 71 86 / 40 50 40 60 LFK 70 88 71 86 / 30 40 40 60 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...NONE. LA...NONE. OK...NONE. TX...NONE. && $$ 15/06 la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1045 PM EDT TUE SEP 4 2007 .UPDATE... ISSUED DENSE FOG ADVY FOR MQT COUNTY WITH VSBYS OVER THE HIER TERRAIN AOB 1/4SM ATTM. EXPECT THE DENSE FOG TO BECOME MORE WDSPRD OVER MORE OF MQT COUNTY LATER AND ACRS MUCH OF THE REST OF INTERIOR WCNTRL UPR MI WITH ARRIVAL OF MID LVL DRYING/CAPPING IN THE WAKE OF H85 WARM FROPA WHILE SFC BNDRY REMAINS TO THE S AND INVRN BECOMES MORE SHALLOW WITH TIME. NO OTHER SITES ARE REPORTING LO VSBYS ATTM...SO WL HOLD OFF ON ADDITIONAL ADVYS FOR A FEW HRS TO SEE HOW FOG DVLPS. BUT EXPECT ADVYS WL BE EVENTUALLY NEEDED FOR AT LEAST ALL THE CNTRL COUNTIES FM IMT-IRON RIVER TO THE KEWEENAW AS MID LVL DRYING OVERSPREADS LLVL MSTR. THE H85 WARM FNT CURRENTLY STRETCHES FM THE KEWEENAW ACRS NRN MQT COUNTY INTO THE ERN ZNS...AS MARKED BY AXIS OF ACCAS AS SHOWN ON VSBL STLT IMAGERY. LATEST RUC SHOWS H85 WARM FROPA ACRS THE E BY 09Z...SO CUT POPS ACRS THE FAR ERN ZNS AFT THAT TIME. DENSE FOG MAY DVLP OVER THE E LATE AS WELL FOLLOWING THIS FROPA. $$ .SHORT TERM (TONIGHT AND WEDNESDAY)... 12Z UPPER AIR ANALYSIS SHOWED TWO MAIN FEATURES PRODUCING THE HEAVY RAIN OVER UPR MI. FIRST WAS H85 WARM FRONT STRADDLING THE SOUTHERN U.P. A SFC WARM FRONT IS NOW JUST EDGING INTO SOUTHERN SECTIONS OF CNTRL UPR MI. SECOND MAIN FEATURE IS 130KT H3 JET OVR ONTARIO. EARLIER TODAY THIS JET WAS CLOSE ENOUGH TO ENHANCE LIFTING ALONG H85 FRONT DUE TO DIVERGENCE ALOFT AND HELPING TO INCREASE FGEN FORCING. THIS AFTN THE JET CONTINUES EAST AND FOR THE MOST PART THE PCPN IS ENDING ACROSS UPR MI. WHAT AN EVENT...FOR AT LEAST PORTIONS OF UPR MI...THIS TURNS OUT TO BE. ALREADY SET ALL TIME DAILY RECORD RAINFALL FOR ANY MONTH...NO LESS SEPTEMBER. PREVIOUS RECORD WAS 4.09 INCHES SET IN JUNE OF 1968. DAILY TOTAL THUS FAR...4.28 INCHES. MOST WE HAVE HEARD IS AROUND 5 INCHES OVR KEWEENAW PENINSULA AND IN EASTERN MQT COUNTY NEAR SKANDIA. A COMPLETE LIST OF TOTALS IS ON OUR WEB SITE AT WWW.WEATHER.GOV/MQT IN THE TOP NEWS OF THE DAY SECTION. AN OFFICIAL RECORD REPORT WILL BE ISSUED THIS EVENING WHEN THE EVENT IS FINISHED. MEANWHILE...NOT A DROP OF RAIN IN SOUTHERN MENOMINEE COUNTY. SO THE TIGHT GRADIENT GUIDANCE SHOWED YDY FOR THE EVENT WAS RIGHT ON. LOCALLY RUN WRF-ARW ALSO DID FAIRLY WELL WITH PCPN AMOUNTS. DO IN LARGE PART TO THE DROUGHT CONDITIONS FOR MOST OF THE SUMMER...THUS FAR...HAVE ONLY HAD REPORTS OF MINOR STREET FLOODING...GRAVEL ROAD WASHOUTS...AND HIGH WATER IN CULVERTS. NO MAJOR FLOODING REPORTED SO FAR. PRETTY AMAZING CONSIDERING VOLUME OF WATER THAT OCCURRED IN SUCH A SHORT PERIOD OF TIME. CURRENT RADAR TRENDS POINT TO ONLY ISOLATED POPS THROUGH THE OVERNIGHT...FOCUSED MAINLY IN THE EAST HALF OF THE CWA. LACK OF STRONG INFLOW INTO THE DECAYING H85 FRONT MINIMIZES THE THREAT OF HEAVY RAIN. CONCERNED THAT ON SOUTHERN EDGE OF CONVECTION THERE MAY BE A CHANCE OF ENHANCED CONVECTION DUE TO LINGERING STRONG DEEP LAYER SHEAR AND MLCAPES CLOSE TO 1500J/KG. THUS FAR...LACK OF MOIST INFLOW INTO THIS AREA IS LIMITING CONVECTION INTENSITY AND COVERAGE. MOVING ON INTO THE LATER EVENING...FOG MAY BECOME A PROBLEM. LOWER LEVEL MOISTURE REMAINS AND MID LEVEL DRYING IS BEGINNING TO TAKE SHAPE. INCLUDED AREAS OF DENSE FOG IN GRIDS. STILL ASSESSING THE NEED FOR AN ADVY. ALREADY SEEING DENSE FOG IN UPSLOPE AREAS OF NCNTRL UPR MI ATTM AT OUR OFFICE NEAR NEGAUNEE. FLIP THE SWITCH FOR THE WEATHER ON WED ONCE WARM FRONT MOVES THROUGH. SFC WINDS SWITCH TO THE SSW WHICH ALLOWS THE HEAT TO REALLY KICK IN. IN FACT...HARD TO BELIEVE I KNOW...BUT SETUP OF H85 TEMPS AROUND 20C AND WSW WINDS (GFS/NAM/UKMET) APPEARS QUITE FAVORABLE FOR WIDESPREAD AROUND 90 READINGS TO OCCUR WED AFTN AWAY FM MODERATION OF LK MICHIGAN. DOWNSLOPING AREAS NEAR LK SUPERIOR (BARAGA TO MARQUETTE TO MUNISING) MAY TRY TO REACH MID 90S. NOT BAD WHEN LOW END OF ENSEMBLE MEAN SHOWS UPR 80S. ALL GUIDANCE IN REALLY GOOD AGREEMENT TO A HOT AND FAIRLY HUMID (DEWPOINTS IN THE LWR 60S) EARLY SEPTEMBER DAY. RECORD HIGH AT NWS MQT OF 88 SET IN 1998 LOOKS IN SERIOUS JEOPARDY. && .LONG TERM (WEDNESDAY NIGHT THROUGH TUESDAY)... TAKING A GLIMPSE AT THE UPPER LEVEL PATTERN...RIDGING WILL START OUT THE PERIOD. IN FACT...RIDGING SHOULD DOMINATE THE EASTERN TWO-THIRDS OF THE NATION. FARTHER TO OUR SOUTH...WE WILL BE WATCHING THE PROGRESSION ON A SHORTWAVE SLIDE NORTHEASTWARD FROM OKLAHOMA AND NEBRASKA...AS IT GETS SCOOPED UP IN THE SOUTHWESTERLY FLOW NEAR US. STILL...THIS IN COMBINATION WITH THE NEXT SHORTWAVE MOVING IN FROM THE WEST...SHOULD BRING OUR NEXT SHOT OF PRECIPITATION TO THE UPPER PENINSULA. AT THE SURFACE...THERE ARE SOME MINOR DISCREPANCIES ON THE THE LOCATION OF THE SURFACE LOW BY 12Z FRIDAY. IN GENERAL...THE SURFACE LOW SHOULD STRETCH FROM CENTRAL ONTARIO SOUTHEASTWARD THROUGH NORTHERN IOWA. UPPER PENINSULA MAINLY STAYS IN THE WARM SLOT UNTIL LATE THURSDAY NIGHT AND DURING THE DAY FRIDAY...WITH THE BEST CHANCE OF SIGNIFICANT RAIN WITH THE PASSAGE OF THE COLD FRONT DURING THE DAYLIGHT HOURS FRIDAY. MAY NEED TO BUMP UP AFTERNOON HIGHS FOR THURSDAY A COUPLE OF MORE DEGREES DEPENDING ON THE STRENGTH AND TIMING OF THE LOW...BUT WILL STICK TO THE LOW TO MID 80S FOR NOW. TEMPERATURES WILL BE KNOCKED DOWN AFTER THIS SYSTEM...WITH HIGHS THROUGH THE REMAINDER OF THE PERIOD IN THE 60S. CLIMATOLOGICALLY...NORMAL HIGH TEMPERATURES FOR THIS TIME OF THE YEAR RIGHT AROUND 70 DEGREES FOR THE MARQUETTE AREA. AS FOR THE EXTENDED FORECAST...DAYS 4 TO 7...SATURDAY THROUGH TUESDAY...HAVE GENERALLY FOLLOWED HPC GUIDANCE. HPC UTILIZED A COMPROMISE SOLUTION WITH THE 00Z NCEP-GEFS AND ECMWF. BASICALLY THIS RESULTED IN A CONTINUED LOW PROBABILITY POP FOR MUCH OF THE EXTENDED...AS THE LARGE 500MB TROUGH REMAINS ENTRENCHED OVER THE NORTHERN TIER OF THE NATION. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... EXPECT DENSE FOG/IFR VSBYS TO DVLP THIS EVNG/OVRNGT UNDER INCRSGLY SHALLOW INVRN AS MID LVL DRYING/CAPPING FOLLOWS PASSAGE OF H85 WARM FNT WHILE SFC WARM FNT REMAINS TO THE S. CONDITIONS SHOULD IMPROVE DRAMATICALLY TO VFR WED MRNG ONCE WARM FNT SHIFTS TO THE N. DIURNAL MIXING WL ALLOW DVLPMNT OF GUSTY SW WINDS AT SAW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRES OVER NORTHEAST ONTARIO WILL BUILD INTO QUEBEC TONIGHT AS A WARM FRONT LIFTS SLOWLY INTO SOUTHERN UPR MI. GUSTY E WINDS TO 25 KT ON LK SUPERIOR WILL DIMINISH BY WED MORNING. ANOTHER BOUT OF STRONG WINDS...THIS TIME FROM THE SOUTH...EXPECTED WED NIGHT INTO THU AHEAD OF TROUGH THAT SHIFTS EAST OUT OF DAKOTAS. SOME GUSTS TO 30 KT ARE POSSIBLE ON THE FAVORED EASTERN LAKE. MORE STRONG SOUTH WINDS POSSIBLE FRI NIGHT AS SFC LOW SHIFTS ACROSS UPR LAKES. WINDS TURNING TO THE NE ON SAT IN THE WAKE OF THE LOW COULD APPROACH 30 KT. NO GALE FORCE WINDS ARE EXPECTED THE ENTIRE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVY MIZ001-003-005 && $$ SHORT TERM...JLA LONG TERM...KF AVIATION...KC MARINE...JLA UPDATE...KC mi AREA FORECAST DISCUSSION...UPDATED AVIATION NATIONAL WEATHER SERVICE MARQUETTE MI 753 AM EDT TUE SEP 4 2007 .SYNOPSIS...ISSUED 415 AM EDT 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED TROUGHING JUST OFF THE PACIFIC NW COAST...UPPER LEVEL RIDGING FROM THE FOUR CORNERS INTO SASKATCHEWAN AND TROUGHING OVER SE CANADA. THIS PLACES UPPER MICHIGAN IN NW FLOW ALOFT...FAVORABLE FOR PRODUCTION OF HIGH PRESSURE AT THE SURFACE AND QUIET WEATHER. THE HIGH IS PRESENT (SITUATED FROM NORTHERN ONTARIO THROUGH LOWER MICHIGAN)...HOWEVER THE WEATHER IS FAR FROM QUIET. LOCAL RADAR LOOP AND LIGHTNING PLOT SHOWS SHOWERS AND THUNDERSTORMS FROM GRAND MARAIS MN ACROSS MUCH OF UPPER MICHIGAN. THIS AREA OF PCPN IS BEING SUPPORTED BY A FEW MECHANISMS: AGEOSTROPHIC FORCING UNDER THE RIGHT ENTRANCE REGION OF A 120 KT UPPER LEVEL JET STREAK EXTENDING FROM NW ONTARIO TO NEAR WAWA...STRONG 800-600MB FRONTOGENESIS...AND LOW LEVEL JET FORCING WHICH IS ADVECTING IN 7-7.5 C/KM 700-500MB LAPSE RATES FROM CENTRAL MN PER RUC ANALYSIS. SOME NOTES ABOUT THE PCPN SO FAR. WE HAD ONE STORM CLOSER TO THE STEEPER LAPSE RATE AREA THAT MAY HAVE COMBINED WITH THE FRONTOGENETICAL CIRCULATION TO PRODUCE SOME SEVERE WEATHER IN GOGEBIC COUNTY. THAT STORM HAS SINCE DIED. THE SECOND NOTE IS WHAT HAS BEEN PLANNED WITH HEAVY RAIN OVER THE KEWEENAW PENINSULA. THE CMX AIRPORT HAS HAD ABOUT 2 INCHES OF RAIN SINCE 8 PM...WHICH HAS BEEN ENOUGH TO PRODUCE SOME STREET FLOODING. SEE THE LATEST ARBFLSMQT FOR MORE INFORMATION. ALL OF THE PCPN IS BEING FOCUSED NORTH OF A SURFACE WARM FRONTAL BOUNDARY...WHICH EXTENDS FROM A 1006MB LOW IN NW SOUTH DAKOTA EASTWARD INTO NORTHERN WISCONSIN. VERY WARM AIR EXISTS SOUTH OF THE FRONT WITH 850MB TEMPS AT 00Z OF 19C AT MPX AND 25C AT BIS AND ABR. FARTHER TO THE SOUTH ON WATER VAPOR...A SURGE OF MOISTURE ASSOCIATED WITH AN UPPER LEVEL LOW IN TEXAS HAS BEEN MOVING NORTHWARD. HIGH CLOUDS CAN NOW BE SEEN IN SE KANSAS. THIS FEATURE MAY HAVE SOME IMPLICATIONS IN THE FORECAST TOWARDS THU. && .DISCUSSION... MAIN FORECAST CONCERNS ARE PCPN TODAY INTO TONIGHT...THEN HOW WARM IT GETS ON WED. TODAY...UPPER RIDGE OVER SASKATCHEWAN WILL BUILD EASTWARD INTO MONTANA IN RESPONSE TO THE EAST PACIFIC TROUGH MOVING INLAND. SINCE THE RIDGE AXIS IS STILL OFF TO THE WEST...UPPER MICHIGAN WILL REMAIN IN NW FLOW ALOFT. THUS...THE WARM FRONTAL BOUNDARY OVER NORTHERN WI WILL LIKELY REMAIN STATIONARY. ISENTROPIC LIFT AND MID-LEVEL FRONTOGENESIS IS PROGGED TO CONTINUE NORTH OF THE BOUNDARY BY THE NAM/GFS...WHICH WOULD SUGGEST CONTINUED PRECIPITATION PRODUCTION. HOWEVER...THE HEAVIEST PCPN IS EXPECTED THIS MORNING WHEN THE AREA IS UNDER THE RIGHT ENTRANCE REGION OF THE SE MOVING 120 KT JET STREAK. THIS AFTERNOON...MODELS PROG THE JET MOVING INTO SW QUEBEC...THUS REDUCING THE UPPER LEVEL DIVERGENCE. IT APPEARS THAT THE PRECIPITATION MAY TRANSITION TO LIGHT RAIN OR DRIZZLE...BUT FOR SIMPLICITY IN THE FORECAST...WILL JUST MENTION LIGHT RAIN. ALL THE CLOUDS...LIKELY WITH LOW CEILINGS...AND RAIN WILL KEEP TEMPERATURES DOWN. MOST LOCATIONS IN THE U.P. SHOULD SEE HIGHS IN THE 60S... EXCEPT FOR RIGHT ALONG THE WISCONSIN BORDER WHERE MORE SUN CAN OCCUR...AND WITH 850MB TEMPS THERE AROUND 16C AT 18Z SUPPORTS HIGHS GETTING CLOSE TO 80. TONIGHT...MODELS PROG THE UPPER RIDGE AXIS SHIFTING EAST TO THE WESTERN CWA BY 12Z WED...APPARENTLY MORE CAUSED BY THE WESTERN TROUGH SPLITTING INTO TWO AND THE NORTHERN PORTION PUSHING THE RIDGE. THE RESULT WILL BE TO BEGIN LIFTING BOTH THE SURFACE AND 850MB WARM FRONTS NORTH OF THE AREA...THOUGH IT APPEARS MORE ADVECTION WILL OCCUR WITH THE WEST SIDE OF THE FRONT THAN THE EAST SIDE. THUS...HAVING THE POPS END OVERNIGHT IN THE WEST HALF OF THE U.P. STILL LOOKS GOOD. GUIDANCE HAS BEEN HINTING AT SOME BR OR FOG...LIKELY DUE TO ADVECTION IN OF SOME HIGHER DEWPOINTS AT THE SURFACE. HAVE DECIDED TO INSERT SOME PATCHY FOG. THESE HIGHER DEWPOINTS...ALONG WITH CLOUDS NORTH OF THE WARM FRONT...WILL ALSO HELP TO KEEP TEMPERATURES FROM FALLING MUCH ACROSS THE CWA. 55 TO 60 READINGS SUGGESTED BY GUIDANCE SEEM REASONABLE. WED...ALL SIGNS ARE POINTING TO A VERY WARM DAY...ALONG WITH SOME HUMIDITY FROM DEWPOINTS CLIMBING INTO THE LOW 60S...AS THE UPPER RIDGE AXIS MOVES OVER ALL OF THE CWA AT 18Z...CAUSING THE SURFACE WARM FRONT TO MOVE NORTH OF THE AREA. IN THE WARM SECTOR...WHERE 850MB TEMPS ARE PROGGED BETWEEN 18-20C...RH PLOTS ONLY SHOW THE TYPICAL CONVECTIVE ROLLS OF CUMULUS DEVELOPING DURING THE AFTERNOON. GIVEN THE 850MB READINGS AND 10-15 MPH SSW WINDS AND PLENTY OF SUN...READINGS SHOULD CLIMB INTO THE MID TO UPPER 80S OVER THE WEST HALF OF THE CWA. HAVE FOLLOWED OUR 30-DAY BIAS CORRECTED GUIDANCE WHICH SUGGESTS A FEW SPOTS TOUCHING 90 (I.E. PELKIE...LA BRANCHE...STEPHENSON). EVEN MARQUETTE COULD GET CLOSE TO 90. THE EAST HALF OF THE CWA WILL HAVE TO CONTEND WITH FLOW OFF LAKE MICHIGAN AND MORNING CLOUDS NORTH OF THE WARM FRONT...THUS COOLER TEMPERATURES ARE EXPECTED THERE. WED NIGHT...NORTHERN PORTION OF THE SPLIT WESTERN TROUGH IS PROGGED TO HEAD UP TOWARDS HUDSON BAY. ASSOCIATED WITH THE TROUGH WILL BE A COLD FRONT ADVANCING EASTWARD FROM THE PLAINS. HOWEVER...GIVEN THAT THE FRONT IS BECOMING MORE AND MORE PARALLEL WITH THE UPPER FLOW DURING THIS PERIOD...IT WILL LIKELY TAKE A WHILE TO GET HERE. BY 12Z THU...THE GFS/NAM/UKMET ALL DEPICT THE FRONT NEAR AITKIN MINNESOTA. A SOUTHWESTERLY LOW LEVEL JET AHEAD OF THE FRONT...COMBINED WITH THE DEWPOINTS IN THE LOW TO MID 60S AND WARM TEMPS FROM WED SUGGESTS TEMPS MAY NOT DROP THAT MUCH. IN FACT...OUR BIAS CORRECTED GUIDANCE KEEPS SOME OF THE DOWNSLOPE SW FLOW AREAS (I.E. COPPER HARBOR AND MARQUETTE) AT OR ABOVE 70. HAVE FOLLOWED SUIT WITH THIS IDEA FOR THE FORECAST. NO PRECIPITATION IS EXPECTED DURING THE PERIOD AS ANY FORCING MECHANISMS ARE LOCATED WELL NORTH OF THE AREA AND WITH THE UPPER LOW OVER TEXAS PROGGED TO BE SITUATED IN NORTHERN MISSOURI. THU THROUGH FRI...THIS PERIOD IS SOMEWHAT UNCERTAIN WITH REGARDS TO WHEN PCPN IS GOING TO OCCUR. ON THU...MODELS TAKE THE UPPER LOW FROM NORTHERN MISSOURI TOWARDS NORTHERN LAKE MICHIGAN. DEEP MOISTURE SPREADING NORTHWARD AHEAD OF THIS UPPER LOW IN ADDITION TO DAYTIME HEATING COULD CONCEIVABLY GENERATE THE TYPICAL SUMMER-TIME STORMS SEEN DOWN IN THE GULF COAST REGION. THIS IS WHAT THE GFS DEPICTS. THEREFORE FOR NOW HAVE DECIDED TO KEEP IN CHANCE POPS. HIGHER CHANCE POPS ARE IN THE FORECAST FOR THU NIGHT INTO FRI WHEN MODELS SHOW THE OTHER PORTION OF THE WESTERN TROUGH MOVING ACROSS. LATEST MODEL GUIDANCE FROM THE ECMWF...GFS...UKMET ARE IN A BIT OF DISAGREEMENT WHETHER IT WILL BE A LOW WITH A COLD FRONT CROSSING (ECMWF/NAM) OR JUST A STRUNG OUT FRONTAL BOUNDARY (GFS/UKMET). EITHER WAY...IT SEEMS LIKE THERE IS POTENTIAL FOR A DECENT RAIN. WILL HAVE TO WAIT A FEW MORE RUNS TO IRON OUT THE DETAILS. AFTER FRI...THE PATTERN BECOMES A BIT MORE FALL-LIKE...BUT TO WHAT INTENSITY REMAINS TO BE SEEN WITH MODELS FAIRLY INCONSISTENT BETWEEN EACH OTHER AND WITHIN THEMSELVES FROM RUN TO RUN. IN ANY EVENT...IT APPEARS TROUGHING WILL DEVELOP OVER CENTRAL CANADA AND INTO THE NORTHERN U.S....WHICH SHOULD HELP DROP 850MB TEMPS DOWN. SOME GFS AND ECMWF RUNS HAVE SHOWN POTENTIAL TO GET THEM CLOSE TO 0C...SUCH AS THE 12Z ECMWF FROM YESTERDAY. HOWEVER...THE 00Z ECMWF HAS BACKED OFF A LOT. THEREFORE...GIVEN THE UNCERTAINTY... && .AVIATION (FOR THE 12Z TAF ISSUANCE)... SHRA/TSRA WILL DIMINISH THIS MORNING AS AREA OF MAX FRONTOGENESIS SLIDES OFF TO THE EAST AND SUPPORT FROM THE LOW LEVEL JET WEAKENS. ALTHOUGH HEAVIER RAIN SHOWERS WILL END...SHALLOW ESE FLOW OF MOISTENED LLVLS TO THE N OF PERSISTENT WARM FNT LAYING ACRS THE UPR MIDWEST SUGS LO CLDS WL PREDOMINATE. DAYTIME HEATING MAY BE SUFFICIENT FOR BRIEF PERIOD OF VFR CONDITIONS LATE TODAY. HOWEVER...WITH ABUNDANT LOW LVL MOISTURE AND LIGHT WINDS EXPECT FOG TO REDEVELOP TONIGHT AND BECOME DENSE. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRES OVER NORTHEAST ONTARIO WILL BUILD INTO QUEBEC TONIGHT AS A WARM FRONT LIFTS SLOWLY TOWARD SOUTHERN UPR MI. THIS WILL RESULT IN 15 TO 25 KT ENE WINDS OVER WESTERN LAKE SUPERIOR AND WINDS BACKING E 10 TO 20 KT OVER THE EAST HALF. OTHERWISE...STRONGER S WINDS EXPECTED MID WEEK AHEAD OF TROUGH THAT SHIFTS EAST OUT OF DAKOTAS. 15 TO 25 KT S TO SW WINDS WITH SOME GUSTS TO 30 KT ARE POSSIBLE ON THE FAVORED EASTERN LAKE LATE WED INTO EARLY THU. WINDS SHOULD REMAIN BLO 30 KT THE REST OF THE FORECAST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...AJ AVIATION/MARIN...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 416 AM EDT TUE SEP 4 2007 .SYNOPSIS... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED TROUGHING JUST OFF THE PACIFIC NW COAST...UPPER LEVEL RIDGING FROM THE FOUR CORNERS INTO SASKATCHEWAN AND TROUGHING OVER SE CANADA. THIS PLACES UPPER MICHIGAN IN NW FLOW ALOFT...FAVORABLE FOR PRODUCTION OF HIGH PRESSURE AT THE SURFACE AND QUIET WEATHER. THE HIGH IS PRESENT (SITUATED FROM NORTHERN ONTARIO THROUGH LOWER MICHIGAN)...HOWEVER THE WEATHER IS FAR FROM QUIET. LOCAL RADAR LOOP AND LIGHTNING PLOT SHOWS SHOWERS AND THUNDERSTORMS FROM GRAND MARAIS MN ACROSS MUCH OF UPPER MICHIGAN. THIS AREA OF PCPN IS BEING SUPPORTED BY A FEW MECHANISMS: AGEOSTROPHIC FORCING UNDER THE RIGHT ENTRANCE REGION OF A 120 KT UPPER LEVEL JET STREAK EXTENDING FROM NW ONTARIO TO NEAR WAWA...STRONG 800-600MB FRONTOGENESIS...AND LOW LEVEL JET FORCING WHICH IS ADVECTING IN 7-7.5 C/KM 700-500MB LAPSE RATES FROM CENTRAL MN PER RUC ANALYSIS. SOME NOTES ABOUT THE PCPN SO FAR. WE HAD ONE STORM CLOSER TO THE STEEPER LAPSE RATE AREA THAT MAY HAVE COMBINED WITH THE FRONTOGENETICAL CIRCULATION TO PRODUCE SOME SEVERE WEATHER IN GOGEBIC COUNTY. THAT STORM HAS SINCE DIED. THE SECOND NOTE IS WHAT HAS BEEN PLANNED WITH HEAVY RAIN OVER THE KEWEENAW PENINSULA. THE CMX AIRPORT HAS HAD ABOUT 2 INCHES OF RAIN SINCE 8 PM...WHICH HAS BEEN ENOUGH TO PRODUCE SOME STREET FLOODING. SEE THE LATEST ARBFLSMQT FOR MORE INFORMATION. ALL OF THE PCPN IS BEING FOCUSED NORTH OF A SURFACE WARM FRONTAL BOUNDARY...WHICH EXTENDS FROM A 1006MB LOW IN NW SOUTH DAKOTA EASTWARD INTO NORTHERN WISCONSIN. VERY WARM AIR EXISTS SOUTH OF THE FRONT WITH 850MB TEMPS AT 00Z OF 19C AT MPX AND 25C AT BIS AND ABR. FARTHER TO THE SOUTH ON WATER VAPOR...A SURGE OF MOISTURE ASSOCIATED WITH AN UPPER LEVEL LOW IN TEXAS HAS BEEN MOVING NORTHWARD. HIGH CLOUDS CAN NOW BE SEEN IN SE KANSAS. THIS FEATURE MAY HAVE SOME IMPLICATIONS IN THE FORECAST TOWARDS THU. && .DISCUSSION... MAIN FORECAST CONCERNS ARE PCPN TODAY INTO TONIGHT...THEN HOW WARM IT GETS ON WED. TODAY...UPPER RIDGE OVER SASKATCHEWAN WILL BUILD EASTWARD INTO MONTANA IN RESPONSE TO THE EAST PACIFIC TROUGH MOVING INLAND. SINCE THE RIDGE AXIS IS STILL OFF TO THE WEST...UPPER MICHIGAN WILL REMAIN IN NW FLOW ALOFT. THUS...THE WARM FRONTAL BOUNDARY OVER NORTHERN WI WILL LIKELY REMAIN STATIONARY. ISENTROPIC LIFT AND MID-LEVEL FRONTOGENESIS IS PROGGED TO CONTINUE NORTH OF THE BOUNDARY BY THE NAM/GFS...WHICH WOULD SUGGEST CONTINUED PRECIPITATION PRODUCTION. HOWEVER...THE HEAVIEST PCPN IS EXPECTED THIS MORNING WHEN THE AREA IS UNDER THE RIGHT ENTRANCE REGION OF THE SE MOVING 120 KT JET STREAK. THIS AFTERNOON...MODELS PROG THE JET MOVING INTO SW QUEBEC...THUS REDUCING THE UPPER LEVEL DIVERGENCE. IT APPEARS THAT THE PRECIPITATION MAY TRANSITION TO LIGHT RAIN OR DRIZZLE...BUT FOR SIMPLICITY IN THE FORECAST...WILL JUST MENTION LIGHT RAIN. ALL THE CLOUDS...LIKELY WITH LOW CEILINGS...AND RAIN WILL KEEP TEMPERATURES DOWN. MOST LOCATIONS IN THE U.P. SHOULD SEE HIGHS IN THE 60S... EXCEPT FOR RIGHT ALONG THE WISCONSIN BORDER WHERE MORE SUN CAN OCCUR...AND WITH 850MB TEMPS THERE AROUND 16C AT 18Z SUPPORTS HIGHS GETTING CLOSE TO 80. TONIGHT...MODELS PROG THE UPPER RIDGE AXIS SHIFTING EAST TO THE WESTERN CWA BY 12Z WED...APPARENTLY MORE CAUSED BY THE WESTERN TROUGH SPLITTING INTO TWO AND THE NORTHERN PORTION PUSHING THE RIDGE. THE RESULT WILL BE TO BEGIN LIFTING BOTH THE SURFACE AND 850MB WARM FRONTS NORTH OF THE AREA...THOUGH IT APPEARS MORE ADVECTION WILL OCCUR WITH THE WEST SIDE OF THE FRONT THAN THE EAST SIDE. THUS...HAVING THE POPS END OVERNIGHT IN THE WEST HALF OF THE U.P. STILL LOOKS GOOD. GUIDANCE HAS BEEN HINTING AT SOME BR OR FOG...LIKELY DUE TO ADVECTION IN OF SOME HIGHER DEWPOINTS AT THE SURFACE. HAVE DECIDED TO INSERT SOME PATCHY FOG. THESE HIGHER DEWPOINTS...ALONG WITH CLOUDS NORTH OF THE WARM FRONT...WILL ALSO HELP TO KEEP TEMPERATURES FROM FALLING MUCH ACROSS THE CWA. 55 TO 60 READINGS SUGGESTED BY GUIDANCE SEEM REASONABLE. WED...ALL SIGNS ARE POINTING TO A VERY WARM DAY...ALONG WITH SOME HUMIDITY FROM DEWPOINTS CLIMBING INTO THE LOW 60S...AS THE UPPER RIDGE AXIS MOVES OVER ALL OF THE CWA AT 18Z...CAUSING THE SURFACE WARM FRONT TO MOVE NORTH OF THE AREA. IN THE WARM SECTOR...WHERE 850MB TEMPS ARE PROGGED BETWEEN 18-20C...RH PLOTS ONLY SHOW THE TYPICAL CONVECTIVE ROLLS OF CUMULUS DEVELOPING DURING THE AFTERNOON. GIVEN THE 850MB READINGS AND 10-15 MPH SSW WINDS AND PLENTY OF SUN...READINGS SHOULD CLIMB INTO THE MID TO UPPER 80S OVER THE WEST HALF OF THE CWA. HAVE FOLLOWED OUR 30-DAY BIAS CORRECTED GUIDANCE WHICH SUGGESTS A FEW SPOTS TOUCHING 90 (I.E. PELKIE...LA BRANCHE...STEPHENSON). EVEN MARQUETTE COULD GET CLOSE TO 90. THE EAST HALF OF THE CWA WILL HAVE TO CONTEND WITH FLOW OFF LAKE MICHIGAN AND MORNING CLOUDS NORTH OF THE WARM FRONT...THUS COOLER TEMPERATURES ARE EXPECTED THERE. WED NIGHT...NORTHERN PORTION OF THE SPLIT WESTERN TROUGH IS PROGGED TO HEAD UP TOWARDS HUDSON BAY. ASSOCIATED WITH THE TROUGH WILL BE A COLD FRONT ADVANCING EASTWARD FROM THE PLAINS. HOWEVER...GIVEN THAT THE FRONT IS BECOMING MORE AND MORE PARALLEL WITH THE UPPER FLOW DURING THIS PERIOD...IT WILL LIKELY TAKE A WHILE TO GET HERE. BY 12Z THU...THE GFS/NAM/UKMET ALL DEPICT THE FRONT NEAR AITKIN MINNESOTA. A SOUTHWESTERLY LOW LEVEL JET AHEAD OF THE FRONT...COMBINED WITH THE DEWPOINTS IN THE LOW TO MID 60S AND WARM TEMPS FROM WED SUGGESTS TEMPS MAY NOT DROP THAT MUCH. IN FACT...OUR BIAS CORRECTED GUIDANCE KEEPS SOME OF THE DOWNSLOPE SW FLOW AREAS (I.E. COPPER HARBOR AND MARQUETTE) AT OR ABOVE 70. HAVE FOLLOWED SUIT WITH THIS IDEA FOR THE FORECAST. NO PRECIPITATION IS EXPECTED DURING THE PERIOD AS ANY FORCING MECHANISMS ARE LOCATED WELL NORTH OF THE AREA AND WITH THE UPPER LOW OVER TEXAS PROGGED TO BE SITUATED IN NORTHERN MISSOURI. THU THROUGH FRI...THIS PERIOD IS SOMEWHAT UNCERTAIN WITH REGARDS TO WHEN PCPN IS GOING TO OCCUR. ON THU...MODELS TAKE THE UPPER LOW FROM NORTHERN MISSOURI TOWARDS NORTHERN LAKE MICHIGAN. DEEP MOISTURE SPREADING NORTHWARD AHEAD OF THIS UPPER LOW IN ADDITION TO DAYTIME HEATING COULD CONCEIVABLY GENERATE THE TYPICAL SUMMER-TIME STORMS SEEN DOWN IN THE GULF COAST REGION. THIS IS WHAT THE GFS DEPICTS. THEREFORE FOR NOW HAVE DECIDED TO KEEP IN CHANCE POPS. HIGHER CHANCE POPS ARE IN THE FORECAST FOR THU NIGHT INTO FRI WHEN MODELS SHOW THE OTHER PORTION OF THE WESTERN TROUGH MOVING ACROSS. LATEST MODEL GUIDANCE FROM THE ECMWF...GFS...UKMET ARE IN A BIT OF DISAGREEMENT WHETHER IT WILL BE A LOW WITH A COLD FRONT CROSSING (ECMWF/NAM) OR JUST A STRUNG OUT FRONTAL BOUNDARY (GFS/UKMET). EITHER WAY...IT SEEMS LIKE THERE IS POTENTIAL FOR A DECENT RAIN. WILL HAVE TO WAIT A FEW MORE RUNS TO IRON OUT THE DETAILS. AFTER FRI...THE PATTERN BECOMES A BIT MORE FALL-LIKE...BUT TO WHAT INTENSITY REMAINS TO BE SEEN WITH MODELS FAIRLY INCONSISTENT BETWEEN EACH OTHER AND WITHIN THEMSELVES FROM RUN TO RUN. IN ANY EVENT...IT APPEARS TROUGHING WILL DEVELOP OVER CENTRAL CANADA AND INTO THE NORTHERN U.S....WHICH SHOULD HELP DROP 850MB TEMPS DOWN. SOME GFS AND ECMWF RUNS HAVE SHOWN POTENTIAL TO GET THEM CLOSE TO 0C...SUCH AS THE 12Z ECMWF FROM YESTERDAY. HOWEVER...THE 00Z ECMWF HAS BACKED OFF A LOT. THEREFORE...GIVEN THE UNCERTAINTY... && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT MORE NMRS SHRA/TSRA TO ARRIVE EARLY THIS MRNG AS BETTER FORCING IN RRQ OF UPR JET NOW MOVING N OF INL ARRIVES. COMBINATION OF ENHANCED UVV AND ELEVATED INSTABILITY CLOSE TO MID LVL WARM FNT WL GENERATE WDSPRD SHRA/EMBEDDED TSRA AND POTENTIALLY HVY RA AT CMX/SAW DEPENDING ON WHERE AXIS OF DEEPER CNVCTN DVLPS. AS UPR JET PUSHES AWAY ON TUE AND UPR LVLS DRY OUT...EXPECT SHRA TO DIMINISH. BUT SHALLOW ESE FLOW OF MOISTENED LLVLS TO THE N OF PERSISTENT WARM FNT LAYING ACRS THE UPR MIDWEST SUGS LO CLDS WL PREDOMINATE. IMPROVED FCST CONDITIONS A BIT AS GFS/NAM FCST SDNGS SHOW SUB INVRN LYR A BIT DRIER THAN PREVIOUS FCSTS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRES OVER NORTHEAST ONTARIO WILL BUILD INTO QUEBEC TONIGHT AS A WARM FRONT LIFTS SLOWLY TOWARD SOUTHERN UPR MI. THIS WILL RESULT IN 15 TO 25 KT ENE WINDS OVER WESTERN LAKE SUPERIOR AND WINDS BACKING E 10 TO 20 KT OVER THE EAST HALF. OTHERWISE...STRONGER S WINDS EXPECTED MID WEEK AHEAD OF TROUGH THAT SHIFTS EAST OUT OF DAKOTAS. 15 TO 25 KT S TO SW WINDS WITH SOME GUSTS TO 30 KT ARE POSSIBLE ON THE FAVORED EASTERN LAKE LATE WED INTO EARLY THU. WINDS SHOULD REMAIN BLO 30 KT THE REST OF THE FORECAST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...AJ AVIATION...KC MARINE...JLB mi AREA FORECAST DISCUSSION...UPDATED FOR AVIATION NATIONAL WEATHER SERVICE MARQUETTE MI 130 AM EDT TUE SEP 4 2007 .UPDATE... PREVIOUS SHRA THAT IMPACTED THE NRN TIER COUNTIES DESPITE LINGERING DRY AIR IN THE LLVLS EARLIER HAVE WEAKENED AS PCPN MOVED TOO FAR E OF AREA OF ISENTROPIC ASCENT N OF WARM FNT FOCUSED IN MN. TRAILING AREA OF SHRA/TSRA THAT DVLPD IN NOSE OF SW LLJ IN NE MN (RECENT TAMDAR SDNGS FM BRD-DLH SHOW SW H85 WINDS UP TO 35 KTS) AND IN AREA OF SHARP H85-7 FGEN WELL N OF SFC WARM FNT IN NCNTRL MN ARE MOVING E THRU WRN LK SUP TOWARD THE WRN COUNTIES. AIR IN WARM SECTOR IS RELATIVELY DRY...SO PARCELS HAVE HAD TO BE LIFTED TO H85 WARM FNT TO ACHIEVE CONDENSATION. EXPECT THIS CLUSTER TO IMPACT THE NW ZNS THE NEXT FEW HRS...SO BUMPED UP POPS A BIT EARLIER IN THAT AREA. STILL EXPECTING ANOTHER RUOND OF SHRA/TSRA DVLPMNT OVER NE MN/WRN LK SUP BY 06Z AS ENHANCED DEEP LYR H85-3 QVECTOR CNVGC/UPR DVGC IN RRQ OF UPR JET NOW JUST E OF LK WINNIPEG OVERSPRDS THAT AREA AT NOSE OF H85 JET/SHARP H85-7 FGEN. CORFIDI VECTORS/H85-3 THKNS LINES AND VEERING H85 LLJ SUG THESE SHRA WL PROPAGATE INTO THE CWA LATER AS RRQ OF THE UPR JET OVERSPRDS OUR CWA. STILL EXPECTING THE MAJORITY OF THE SHRA/TSRA TO IMPACT THE N HALF OF THE U.P. CLOSER TO THE SHARPER H85-7 FGEN AND WHERE PARCELS WL HAVE MORE TIME TO SATURATE. HVY RA APPEARS TO BE THE MAIN THREAT WITH CELLS TRACKING ESE OVER THE SAME AXIS OF FGEN...BUT H85-5 BULK SHEAR 40-50KTS SUG POTENTIAL FOR ELEVATED SUPERCELLS/LARGE HAIL DESPITE MORE MARGINAL LAPSE RATES FARTHER N WHERE TS WL BE MORE ELEVATED. FCST SDNGS FOR THE SRN TIER ZNS...WHERE INSTABILITY FCST TO BE GREATER (SSI NR -4C)...SHOW MORE DRY AIR/CAPPING LINGERING THRU THE NGT. RUC FCST SDNG FOR MQT INDICATES 725 J/KG CAPE AT 09Z WHEN LIFTING FM H8. $$ .PREVIOUS DISCUSSION... SYNOPSIS... 12Z UPPER AIR ANALYSIS INDICATED BROAD WEST TO EAST RIDGE ACROSS MUCH OF THE CONUS WHILE SOUTHERN TIER OF CANADA AND FAR NORTHERN TIER OF CONUS IS AFFECTED BY STRONGER H5 FLOW...MORE TYPICAL OF FALL. H2 JET AVERAGING AROUND 85KT IS ALLIGNED FM BRITISH COLUMBIA TO BASE OF TROUGH OVR QUEBEC. JET STREAK AT H2 OF 105KT IS NOTED OVR SASKATCHEWAN. SLOPING WARM FRONTAL ZONE EXTENDS FM EASTERN SD INTO SOUTHERN MN AT THE SFC TO NORTHERN ND INTO CNTRL MN AT H85 AND TO SOUTHERN MANITOBA TO NE MN INTO LK SUPERIOR AT H7. NARROW LINE OF CONVECTION ALONG SFC FRONT...BUT THROUGH EARLY AFTN MAIN FOCUS FOR CONVECTION WAS ALONG AND NORTH OF H85 FRONT. WITHIN LAST COUPLE HOURS CONVECTION IS NOW SURGING INTO WESTERN LK SUPERIOR WITH SOME SPRINKLES AS FAR EAST AS NCNTRL UPR MI. && .SHORT TERM (TONIGHT AND TUESDAY)... MAIN CONCERNS ARE WHERE RAIN SETS UP TONIGHT AND HOW LONG IT PERSISTS INTO TUE. SFC FRONT TRIES TO LIFT INTO UPR MI TONIGHT BUT LOOKS LIKE IT WILL JUST FALL SHORT. H85-H7 FRONTS ARE FIRMLY OVERHEAD THOUGH AND LEAD TO GOOD TEMP GRADIENT AND RESULT IN SHARP FGEN ZONE FM H85-H7. CROSS SECTIONS CONTINUES TO INDICATE NEGATIVE EPV LOCATED JUST ABOVE FGEN SLOPE. LAPSE RATES IN THIS LAYER POINT TO MAINLY UPRIGHT INSTABILITY ALTHOUGH SOME SLANTWISE INSTABILITY IS PRESENT OVER LK SUPERIOR. AS BEFORE...LAYER RH IS ONLY FOCUSED IN NARROW RIBBON. FOCUSING ON NORTH EDGE OF MAX FGEN LEADS TO NORTH HALF OF CWA SEEING THE BEST CHANCE OF RAIN. NEED TO KEEP SCT POPS IN THE SOUTH CLOSER TO SFC FRONT AND INFLUX OF BETTER ELEVATED INSTABILITY. 1-6KM MUCAPES TO 1500J/KG...1-6KM BULK SHEAR OVR 40KT...AND WBZERO HEIGHTS AROUND 11KFT YIELD POSSIBILITY FOR MARGINAL SEVERE HAIL. LOCAL HIGH RES WRF-ARW INDICATED POTENTIAL FOR HEAVY RAIN IN THE NARROW BAND WITH 12 HR AMOUNTS OVR 2 INCHES. CONSIDERING THE AMOUNT OF INSTABILITY AND THE MOIST PROFILES SHOWN ON SOUNDINGS ALONG WITH NARROW CORRIDOR OF CONVECTION THIS CERTAINLY SEEMS PLAUSIBLE. ADDED MENTION OF HVY RAIN WHERE HIGHEST POPS ARE FOCUSED. FGEN AND 300-305K ISENTROPIC LIFT LINGERS INTO TUE...MAINLY NORTH AND EAST. EXPECT BAND OF MODERATE-HEAVY RAIN TO TRANSITION TO MORE OF A LGT RAIN AND DRIZZLE. TEMPS SHOULD BE ABLE TO BOUNCE INTO THE 70S SOUTH CENTRAL IN THE WARM SECTOR OF DECAYING WARM FRONT...BUT IN THE NORTH AND EAST EXPECT TEMPS TO ONLY STRUGGLE INTO THE MID 60S WITH LOTS OF LOW CLOUDS/LGT PCPN/POSSIBLE FOG. EXTENDED...TUESDAY NIGHT THROUGH MONDAY. THE MID LEVEL LOW OVER NORTHERN CALIFORNIA WILL LIFT TO SOUTHERN IDAHO TUESDAY NIGHT WHILE A SHORTWAVE IN THE ZONAL FLOW ACROSS SOUTHERN CANADA DEEPENS OVER MANITOBA. THE HIGH OVER EASTERN ONTARIO WILL SLIDE INTO SOUTHERN QUEBEC...WHILE A COLD FRONT SHIFTS OUT OF THE HIGH PLAINS INTO THE DAKOTAS. UPPER LEVEL DIVERGENCE AND 850-500MB Q-VECTOR CONVERGENCE WILL CONTRIBUTE TO THE INSTABILITY SWEEPING THROUGH THE REGION. DRY AIR ADVECTION WILL CAUSE THE TRW TO END FROM THE NORTHWEST TO SOUTHEAST. MUCAPE VALUES WILL INCREASE OVER THE AREA ON WEDNESDAY. THE EXIT REGION OF THE UPPER LEVEL JET WILL REMAIN OVER CENTRAL ONTARIO. A WEAK SHORTWAVE WILL SWEEP INTO THE AREA WEDNESDAY AFTERNOON. THE SURFACE LOW WILL BE OVER NORTHERN ONTARIO...WITH THE COLD FRONT DRAPED SOUTHWEST INTO WESTERN NEBRASKA AND THE MIDDLE HIGH PLAINS. THE GREATEST ISENTROPIC ASCENT WILL REMAIN WEST OF THE AREA. A SOUTHWEST FLOW AHEAD OF THIS FRONT WILL DRAW WARM AIR IN THE AREA PUSHING TEMPERATURES UP INTO THE UPPER 80S. THE 850MB THETA-E RIDGE WILL MOVE INTO WISCONSIN...BUT SHOULD REMAIN SOUTH OF THE FORECAST AREA. THE AIR MASS LOOKS AS IF WILL BE TOO DRY TO SUSTAIN ANY APPRECIABLE PRECIPTATION EXCEPT FOR NORTHERN AND EASTERN LAKE SUPERIOR. MORE STABLE AIR WILL WORK INTO THE AREA WEDNESDAY NIGHT AS DRY AIR REMAINS ENTRENCHED. A WEAK SHORTWAVE WILL TRACK INTO WISCONSIN WEDNESDAY NIGHT AND THROUGH THE FORECAST AREA IN THURSDAY. ISENTROPIC ASCENT WILL INCREASE OVER THE AREA AS THE COLD FRONT MOVES INTO CENTRAL MINNESOTA AND CENTRAL ONTARIO. THE UPPER LEVEL JET WILL STAY OVER NORTHERN ONTARIO. THE THETA-E RIDGE AND THE MEAN SURFACE-500MB RH WILL EXPAND OVER THE FORECAST DURING THE DAY. AVAILABLE MOSTURE WILL BE LIMITED...THEREFORE...WILL CONTINUE WITH LIGHT POPS FOR NOW. THE SHORTWAVE OVER THE NORTHERN PLAINS WILL SHIFT NORTHEAST ACROSS THE FORECAST AREA THURSDAY NIGHT. THE SURFACE LOW WILL PUSH INTO WEST CENTRAL QUEBEC PULLING THE COLD FRONT AND ACCOMPANYING DEEP MOISTURE ACROSS THE FORECAST AREA. ANOTHER WEAK SHORTWAVE WILL TRACK THROUGH THE FORECAST ON FRIDAY. IT APPEARS THAT THERE WILL BE ENOUGH LOW LEVEL MOISTURE AVAILABLE TO FEED MORE SHOWERS... ESPECIALLY WITH SOME AFTERNOON HEATING. THERE WILL STILL A LITTLE SOME INSTABILITY. WILL KEEP SHOWERS AND THUNDERSTORMS GOING THROUGH FRIDAY. ANOTHER WEAK SHORTWAVE WILL RACE ACROSS THE FORECAST AREA FRIDAY AND SATURDAY AS ANOTHER WEAKER COLD FRONT SWEEPS THROUGH THE AREA. MOISTURE WILL BE LIMITED...BUT THERE MAY STILL BE ENOUGH PRESENT TO CONTINUE TO MENTION A CHANCE OF SHOWERS AND THUNDERSTORMS WITH LOWER POPS. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT MORE NMRS SHRA/TSRA TO ARRIVE EARLY THIS MRNG AS BETTER FORCING IN RRQ OF UPR JET NOW MOVING N OF INL ARRIVES. COMBINATION OF ENHANCED UVV AND ELEVATED INSTABILITY CLOSE TO MID LVL WARM FNT WL GENERATE WDSPRD SHRA/EMBEDDED TSRA AND POTENTIALLY HVY RA AT CMX/SAW DEPENDING ON WHERE AXIS OF DEEPER CNVCTN DVLPS. AS UPR JET PUSHES AWAY ON TUE AND UPR LVLS DRY OUT...EXPECT SHRA TO DIMINISH. BUT SHALLOW ESE FLOW OF MOISTENED LLVLS TO THE N OF PERSISTENT WARM FNT LAYING ACRS THE UPR MIDWEST SUGS LO CLDS WL PREDOMINATE. IMPROVED FCST CONDITIONS A BIT AS GFS/NAM FCST SDNGS SHOW SUB INVRN LYR A BIT DRIER THAN PREVIOUS FCSTS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRES SLIDES ACROSS THE WESTERN GREAT LAKES THROUGH TONIGHT WITH A WARM FRONT LIFTING TOWARD SOUTHERN UPR MI. RESULT IS ENE WINDS INCREASING OVR WESTERN LAKE WITH 30 KT POSSIBLE LATER THIS EVENING INTO EARLY ON TUE. OTHERWISE...STRONGER S WINDS EXPECTED MID WEEK AHEAD OF TROUGH THAT SHIFTS EAST OUT OF DAKOTAS. 30 KT POSSIBLE ON THE FAVORED EASTERN LK LATE WED INTO EARLY THU. WINDS SHOULD REMAIN BLO 30 KT THE REST OF THE FORECAST PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...JLA EXTENDED TERM...DLG MARINE...JLA AVIATION...KC UPDATE...KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 131 PM EDT MON SEP 3 2007 UPDATED AVIATION DISCUSSION FOR 18Z TAFS .UPDATE... TEMPS/WINDS IN GOOD SHAPE. DID INCREASE CLOUDS A BIT QUICKER AS AREA OF H7 FGEN AND RIBBON OF H7 MOISTURE EXTENDS INTO NORTHERN SECTIONS OF UPR MI. RADAR FM MN SHOWS JUST A SMATTERING OF SHOWERS MOVING TOWARD THE ARROWHEAD CLOSE TO FRONT AT H85. MORE CONCENTRATED SHOWERS/THUNDERSTORMS ARE OCCURRING OVR SOUTHERN MANITOBA INTO ADJACENT NW ONTARIO ALONG THE H7 FRONT. ADDED SOME SLIGHT CHANCE POPS INTO WESTERN LK SUPERIOR LATE TODAY AS SHOWERS OVR MN SHIFT EASTWARD WITH INITIAL SURGE OF MID LEVEL FGEN. APPEARS THAT SOME AREAS OF CWA WILL SEE MODERATE-HEAVY RAIN OVERNIGHT INTO TUE. TROUBLE IS...THAT CORRIDOR OF HEAVIEST RAIN WILL BE CONVECTIVE AND FAIRLY NARROW. BASED ON WHERE STRONGEST H85-H7 FGEN AND THE GREATEST MOISTURE ARE EXPECTED TO COMBINE...THINK THE NORTHERN HALF OF CWA SEES THE BEST CHANCE OF RAIN. 12Z NAM SHOWS MAX QPF AXIS CENTERED IN THIS AREA...A SLIGHT NORTHWARD ADJUSTMENT TO ITS 06Z PREDECESSOR. BASED ON LATEST DATA...CURRENT GRIDS IN FINE SHAPE WITH EXPECTED COVERAGE OF PCPN TONIGHT/TUE. && .SYNOPSIS... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A STRONG TROUGH BARRELING TOWARDS THE PACIFIC NW...RIDGING EXTENDING FROM THE FOUR CORNERS UP INTO SOUTHERN ALBERTA AND SASKATCHEWAN...AND TROUGHING OVER NE ONTARIO INTO QUEBEC. WITH UPPER MICHIGAN SITUATED BETWEEN THE RIDGE AND TROUGH...CONDITIONS ARE QUIET WITH HIGH PRESSURE BUILDING IN FROM MINNESOTA AT THE SURFACE. SKIES ARE MOSTLY CLEAR WHILE DEWPOINTS AND TEMPERATURES CONTINUE TO FALL WITH THE HIGH BUILDING IN. SOME INLAND READINGS HAVE DROPPED INTO THE LOW TO MID 40S. TO THE NW...AN AREA OF HIGH AND MID LEVEL CLOUDS CAN BE SEEN SPREADING SE FROM SOUTHERN SASKATCHEWAN...SOUTHERN MANITOBA...EASTERN NORTH DAKOTA AND NORTHERN MN. RADAR IMAGERY FROM GRAND FORKS ALSO SHOWS BANDS OF LOW REFLECTIVITIES WITHIN THESE CLOUDS...THOUGH DRY LOW TO MID LEVELS SEEN ON THE 00Z BIS AND INL SOUNDINGS HAS KEPT MUCH OF THE PCPN AS VIRGA. LIGHTNING PLOTS ALSO INDICATE A FEW STRIKES...INDICATIVE OF SOME NEGATIVE EPV. IN THIS CASE AND USUAL FOR THE SUMMER...MUCH OF THE EPV IS UPRIGHT INSTABILITY DUE TO 700-500MB LAPSE RATES AROUND 7-7.5C/KM. THIS AREA OF CLOUDS IS SITUATED SOUTH OF A 90 KT JET STREAK STRETCHING FROM CENTRAL SASKATCHEWAN INTO NW ONTARIO...IN AN AREA OF 800-600MB FRONTOGENESIS...AND WELL NORTH OF A SURFACE WARM FRONT WHICH EXTENDS FROM SIOUX FALLS SOUTH DAKOTA NW TO A 1007MB LOW IN SE MONTANA. && .DISCUSSION... MAIN FORECAST CONCERN IS PCPN CHANCES/LOCATION AND HOW MUCH PCPN FOR TONIGHT AND TUE. TODAY...MUCH OF THE DAY IS EXPECTED TO BE QUIET WITH HIGH PRESSURE EVENTUALLY ENCOMPASSING MUCH OF THE CWA BY 18Z. HOWEVER...HIGH AND MID CLOUDS WILL DEFINITELY BE ON THE INCREASE AS THE 90-100 KT JET STREAK MOVES TO JET NORTH OF LAKE SUPERIOR AND MID-LEVEL FRONTOGENESIS SHIFTS EAST INTO THE U.P.. A FEW SHOWERS OR THUNDERSTORMS MAY ALSO TRY TO ENTER WESTERN LAKE SUPERIOR LATE THIS AFTERNOON WITHIN THE FRONTOGENESIS AREA AND RIGHT ENTRANCE REGION OF THE 90-100 KT JET...THUS HAVE MAINTAINED THE GOING 20 POPS. ALTHOUGH 850MB TEMPS ARE PROGGED AROUND 14C WHICH WOULD SUPPORT HIGHS IN THE LOW 80S...THE INCOMING CLOUD ALONG WITH LAKE BREEZES SHOULD KEEP TEMPERATURES A FEW DEGREES COOLER THAN THAT. TONIGHT INTO TUE...LARGE TROUGH OFF THE WEST COAST IS PROGGED TO MOVE ONSHORE DURING THIS PERIOD...FORCING RIDGING TO BUILD DOWNSTREAM OF IT ACROSS THE NORTHERN PLAINS INTO SOUTH CENTRAL CANADA. THIS BUILDING RIDGE...COMBINED WITH TYPICAL DIURNAL AFFECTS...WILL RESULT IN THE DEVELOPMENT OF A LOW LEVEL JET THIS EVENING FROM NEBRASKA UP INTO MN...LIFTING THE SURFACE WARM FRONT TOWARDS THE AREA. HOWEVER...WITH NW FLOW ALOFT...COOLER AIR OVER NORTHERN ONTARIO REMAINS STATIONARY. THE NET RESULT THEN IS TO TIGHTEN UP THE LOW LEVEL THERMAL GRADIENT ACROSS UPPER MICHIGAN... NORTHERN MN AND FAR WESTERN ONTARIO...THUS INCREASING ISENTROPIC LIFT...MID-LEVEL FRONTOGENESIS AND THE UPPER LEVEL JET. IN ADDITION...THE LOW LEVEL JET WILL HELP TO ADVECT IN NEGATIVE EPV INTO THE AREA WITH CROSS-SECTIONS SUGGESTING POTENTIAL FOR BOTH UPRIGHT AND SYMMETRIC CONVECTION. THEREFORE...A FAVORABLE RAIN SCENARIO IS SHAPING UP...PARTICULARLY AFTER MIDNIGHT INTO TUE MORNING WHEN ALL THREE ARE PROGGED TO BE JUXTAPOSED. THE 00Z GFS AND NAM HAVE SOME VERY IMPRESSIVE 12 HOUR QPF AMOUNTS FROM 06-18Z...WITH THE BROADER RESOLUTION GFS SHOWING 1-1.5 INCHES FROM THE KEWEENAW INTO CHIPPEWA COUNTY AND THE HIGHER RESOLUTION NAM SHOWING 1.5-3 INCHES FROM THE KEWEENAW INTO SCHOOLCRAFT COUNTY. IN BOTH MODELS... VERY LITTLE FALLS ALONG THE WISCONSIN BORDER AND AT THE NE END OF THE LAKE...REALLY INDICATING HOW NARROW THIS BANDING WILL END UP. COMPARE THIS TO OUR LOCAL WRF-ARW RUNS WHERE ITS QPF IT HAS THE SAME WIDTH OF PCPN...JUST SHIFTED TO THE SW ALLOWING MARQUETTE COUNTY TO GET UP TO 3 INCHES OF RAIN. THE REGIONAL CANADIAN...ON THE OTHER HAND...HAS MOST OF THE QPF OVER LAKE SUPERIOR...BUT STILL IMPACTS THE KEWEENAW AND EASTERN U.P.. FOR NOW HAVE DECIDED TO RAISE POPS UP TO 70 FOR THE NORTHERN AND EASTERN U.P. WITH QPF AMOUNTS SIMILAR TO THE GFS. BOTH POPS AND QPF WILL PROBABLY HAVE TO BE ADJUSTED SPATIALLY AND UP OR DOWN LATER TODAY (NEW 06Z NAM DEPICTS CONTINUED ISSUES WITH HIGHEST QPF AXIS NEAR WI BORDER). NO MATTER WHERE THE RAIN FALLS...IT WILL BE VERY HELPFUL. IT APPEARS THAT MUCH OF THE RAIN SHOULD BE DONE BY 18Z...WITH ONLY LIGHT SHOWERS CONTINUING TO 00Z DUE TO WEAKER MID-LEVEL FRONTOGENESIS. TUE NIGHT INTO WED...WESTERN TROUGH IS PROGGED TO CONTINUE MOVING SLOWLY EAST...REACHING EASTERN IDAHO BY 00Z THU. AS A RESULT...UPPER RIDGING OVER THE NORTHERN PLAINS WILL SHIFT OVER MICHIGAN BY 18Z WED. WARM ADVECTION UNDERNEATH THE RIDGE SHOULD LIFT THE SURFACE WARM FRONT OVER THE CWA BY 12Z WED AND THEN COMPLETELY NORTH OF THE AREA BY 00Z. WILL CONTINUE CHANCE POPS FOR THE ISENTROPIC LIFT OCCURRING NORTH OF THE WARM FRONT. ONCE THE FRONT PASSES...EXPECT SKIES TO CLEAR WITH ONLY SOME HORIZONTAL CONVECTIVE ROLL CUMULUS DURING THE DAYTIME IN THE WARM SECTOR. MODELS ARE IN GOOD AGREEMENT SHOWING 850MB TEMPS CLIMBING TO 18-20C BY 18Z WED...AND WITH A 10-15 MPH SOUTH WIND...SURFACE TEMPERATURES ARE EXPECTED TO GET QUITE WARM. MET GUIDANCE IS ALMOST 90 AT IMT. MADE ONLY SLIGHT ADJUSTMENTS TO THE GOING TEMPERATURE GRIDS. WED NIGHT INTO THU NIGHT...UPPER TROUGH IS PROGGED TO EJECT OUT INTO THE NORTHERN PLAINS IN RESPONSE TO A LARGER TROUGH DROPPING THROUGH ALBERTA. THIS TROUGH WILL SEND A COLD FRONT EASTWARD TOWARDS MINNESOTA BY 00Z FRI PER 00Z ECMWF/GFS/CANADIAN. A DRY...WARM AND HUMID WED NIGHT IS EXPECTED WITH THE AREA GENERALLY UNDER UPPER RIDGING. HOWEVER...ON THU...THE FLOW TURNS SOUTHWESTERLY. WITHIN THIS FLOW...MODELS SUGGEST A PORTION OF THE CURRENT UPPER LOW IN SOUTH TEXAS LIFTING UP ACROSS THE CWA ON THU. THUS HAVE MAINTAINED GOING CHANCE POPS AND MOSTLY CLOUDY SKIES. THESE CLOUDS SHOULD KEEP TEMPERATURES CLIMBING AS HIGH AS ON WED. BEST CHANCE FOR RAIN AT THIS TIME APPEARS TO BE ON THU NIGHT AS UPPER TROUGH AND COLD FRONT APPROACH THE CWA. THE RAIN COULD BE HEAVY TOO...GIVEN A DEEP TROPICAL CONNECTION FROM THE GULF OF MEXICO (850MB DEWPOINTS PROGGED AROUND +14C) AND UPPER LEVEL MOISTURE STREAMING NE OFF TROPICAL STORM HENRIETTE IN THE EAST PACIFIC. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... SFC WARM FRONT SITS FM SOUTHERN MN INTO CNTRL WI. MEANWHILE...A WARM FRONT ALOFT 5000-10000 FT RUNS FM ND INTO NORTHERN MN/ADJACENT MANITOBA AND ONTARIO AND INTO FAR WEST LK SUPERIOR. A DISTURBANCE RIDING ALONG THE WARM FRONTS ALOFT WILL ALLOW SHOWERS AND EMBEDDED THUNDERSTORMS TO SWEEP SE TOWARD THE KEWEENAW LATE EVENING AND AFT MIDNIGHT AT KSAW. DECENT AMOUNT OF INSTABILITY ALOFT TONIGHT THAT THERE COULD BE A GOOD LIGHTNING SHOW WITH THE EMBEDDED THUNDERSTORMS. AT THE LEAST...RAIN SHOULD FALL HEAVY OVERNIGHT AT EITHER OR BOTH SITES. STEADY RAIN SHOULD DECREASE LATE TONIGHT TOWARD DAYBREAK ON TUE. FORCING FOR AT LEAST SOME LGT RAIN THEN CONTINUES THROUGH THE TAF PERIOD. MAIN FOCUS BY LATE TONIGHT AND ESPECIALLY INTO TUE WILL BE DEVELOPING LOWER CIGS AND VSBY AS SFC WARM FRONT STRADDLES SOUTHERN U.P. EXPECTED E/SE WINDS FAVORS UPSLOPE ENHANCEMENT FOR LOWER CIGS/VSBY AT BOTH SITES. IFR FLIGHT CATEGORY POTENTIAL SEEMS HIGH ENOUGH TO INCLUDE FOR BOTH TAFS. COULD EVEN SEE LOWER CONDITIONS IF DRYING ALOFT TAKES HOLD... CHANGING LINGERING LGT RAIN INTO MORE OF A DRIZZLE. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRES WILL SLIDE ACROSS THE WESTERN GREAT LAKES TODAY AND SHIFT INTO NORTHEAST ONTARIO TUE AS LOW PRES DEVELOPS OVER THE NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY. AS A RESULT...LIGHT NORTHWEST WINDS WILL BECOME EASTERLY TONIGHT AND INCREASE TUE AS A WARM FRONT DEVELOPS OVER NORTHERN WISCONSIN. ANOTHER LOW PRESSURE TROUGH WILL DEVELOP OVER THE NORTHERN PLAINS ON WED. SOUTHERLY WINDS WILL INCREASE AHEAD OF THE LOW...WITH WINDS ON EASTERN LAKE SUPERIOR INCREASING TO 20 TO 25 KT WED INTO THU. THE TROUGH ASSOCIATED WITH THIS LOW IS EXPECTED TO CROSS LAKE SUPERIOR LATE THU NIGHT AND FRI. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JLA DISCUSSION...AJ AVIATION...JLA MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 100 PM EDT MON SEP 3 2007 .AVIATION... SURFACE FRONT HAS ALL BUT WASHED OUT...WITH WEAK SURFACE RIDGE EXPECTED TO PROVIDE VERY LIGHT WINDS AND VFR CONDITIONS THROUGH THE TAF PERIOD. WARM FRONT SLIDING INTO THE WESTERN GREAT LAKES SHOULD ALLOW FOR SOME MID/HIGH CLOUDS TO SPILL INTO LOWER MICHIGAN LATE TONIGHT/TOMORROW MORNING. && .PREV DISCUSSION...ISSUED 411 AM EDT MON SEP 3 2007 SHORT TERM...TODAY WEAK SURFACE COLD FRONT IS EXPECTED TO PRETTY MUCH WASH OUT AS IT SINKS SOUTHWARD THROUGH THE FORECAST AREA TODAY...BENEATH NORTHWEST FLOW ALOFT. DYNAMIC ASCENT SUPPORT EXPECTED TO BE VERY LIMITED AT BEST TODAY. LITTLE OR NO LOW TO MID LEVEL OMEGA ASCENT OR QVECTOR CONVERGENCE...WITH 305K TO 310K ISENTROPIC ASCENT SLIGHT AT BEST. MODEST SURFACE WIND CONVERGENCE TODAY THOUGH...MAINLY THIS AFTERNOON. MODEST INSTABILITY EXPECTED THIS AFTERNOON IN SOUTHERN COUNTIES AHEAD OF COLD FRONT...BUT MODEL FORECAST SOUNDINGS SHOW QUITE A BIT OF CAPPING BELOW 700 MB TO INHIBIT CONVECTION. WILL CONTINUE A DRY FORECAST TODAY...AS MODELS ALSO CONTINUE TO ADVERTISE VERY LIMITED MOISTURE. QPF AS PER MODELS FOR TODAY IS VIRTUALLY NON EXISTENT...THOUGH 4KM NMM WRF AND RUC13 GIVE A SLIGHT HINT OF A LOCAL SPRINKLE OR LIGHT SHOWER. WATER VAPOR IMAGERY SHOWS A DRYING TREND ALOFT...AND SATELLITE/METAR OVERNIGHT TRENDS OF LOW TO MID CLOUDS IN MOISTURE AXIS PRECEDING THE FRONT WOULD SUPPORT ONLY A PARTIAL CLOUD COVER TODAY. SAME TRUE OF ANY DIURNAL CUMULUS DEVELOPMENT AS PER AWIPS CUMULUS SCHEME. TEMPERATURES TODAY SHOULD REACH AROUND 80 NORTH...AND MID 80S SOUTH AS SUPPORTED BY T1 TEMPERATURES. LONG TERM...MONDAY NIGHT THROUGH SUNDAY CHALLENGES OF THE LONG TERM FORECAST CENTER ON PRECIPITATION CHANCES FOR TUESDAY/THUR-SAT. BUST POTENTIAL OF MAX TEMPERATURES FOR TUESDAY AND THURSDAY ARE ALSO A CONCERN. BY TOMORROW EVENING THE MIDLEVEL COLD FRONT AND THETA E GRADIENTS WILL BE ALIGNED NORTHWEST TO SOUTHEAST FROM NORTHERN MINNESOTA THROUGH SOUTHEASTERN MICHIGAN TO NORTHERN PENNSYLVANIA. ON THE NORTHERN PERIPHERY OF THE UPPER LEVEL RIDGE AND IN VICINITY TO MIDLEVEL THERMAL BOUNDARIES PLACES LAKE HURON AND PORTIONS OF SOUTHEASTERN LOWER IN PRIME DOWNSTREAM LOCATION OF THE MCS ACTIVITY ACROSS THE NORTHERN PLAINS/SOUTH CENTRAL CANADA. CONVECTIVE INITIATION TOMORROW AFTERNOON ACROSS LAKE WINNIPEG/NORTHERN MINNESOTA APPEARS LIKELY AS A SURFACE WARM FRONT SHARPENS IN RESPONSE TO NORTHERN PLAINS CYCLOGENESIS. A ZONAL WEST TO EAST LOW LEVEL JET REACHING 35 KNOTS WILL FORCE ANY PRECIPITATION EAST SOUTHEASTWARD THROUGHOUT THE NIGHT. DESPITE AN UNSTABLE ENVIRONMENT ACROSS THE SOURCE REGION LATEST GUIDANCE IS SHOWING NOTHING IN THE WAY OF NEGATIVE SHOWALTERS IN THIS AREA AND IS EVEN HAVING A DIFFICULT TIME GENERATING CONVECTIVE PRECIPITATION. ATTM...BELIEVE THE BULK OF THE PRECIPITATION ACROSS THE NORTH (STARTING AFTER MIDNIGHT) AND LASTING FOR A BETTER PART OF THE DAY WILL BE STRATIFORM IN NATURE WITH A FEW LIGHTNING STRIKES POSSIBLE. THE PRECIPITATION CHANCES WILL MAINLY BE FOR LAKE HURON...BUT PORTIONS OF THE THUMB AND SAGINAW RIVER VALLEY WILL HAVE A SHOT FOR SOME RAINFALL MAINLY DURING THE DAYLIGHT ON TUESDAY. THE TUESDAY TEMPERATURE FORECAST FOR THIS ISSUANCE IS ON THE COLD SIDE WITH THE ANTICIPATED CLOUD COVER...SO ANY THINNING OR BREAKS TO THE CANOPY COULD SEND TEMPERATURES UPWARD. THE MIDLEVEL WARM FRONT SURGES NORTHWARD UNDER RAPIDLY AMPLIFYING UPPER LEVELS ON WEDNESDAY. HIGH TEMPERATURES ON WEDNESDAY ARE EXPECTED TO BE IN THE MID TO UPPER 80S IN INCREASING SOUTHWESTERLY FLOW. THE LATEST 00Z GFS IS BACK TO THE MAJOR PHASING/STRONG SURFACE CYCLOGENESIS EVENT BEGINNING ON THURSDAY. THE PRIMARY PLAYERS AGAIN ARE THE QUASI-CUTOFF ENERGY OVER THE GREAT BASIN...SOME DISORGANIZED WAVE ENERGY SURGING NORTHWARD OUT OF WESTERN TEXAS...AND THE STRONG DYNAMIC WAVE CRASHING ONSHORE OFF THE PACIFIC WEDNESDAY NIGHT. RISING HEIGHTS ACROSS THE EAST SHOULD BLOCK THE WESTERLY FLOW ENOUGH ALLOWING FOR THE REASONABLE SOLUTION OF PHASING AND RESULTANT DEEPENING. PLENTY OF TIME REMAINS TO REFINE THE FORECAST FOR THIS SYSTEM BUT HAVE DECIDED ON INSERTING POPS ONCE AGAIN FOR THURSDAY NIGHT. THE ADVERTISED STRONG TO INTENSE HEIGHT FALLS ACROSS THE UPPER MIDWEST WOULD ALLOW FOR THE QUICK GENERATION OF A STRONG SOUTHERLY LOW LEVEL JET AND ASSOCIATED MOISTURE SURGE. EMBEDDED SHORTWAVES IN THE SOUTHERLY FLOW SHOULD ALLOW FOR ENOUGH SYNOPTIC SUPPORT IN GENERAL ISENTROPIC REGIME TO GENERATE SHOWERS AND THUNDERSTORMS THURSDAY NIGHT. UPPER LEVEL CIRRUS AND DEBRIS CLOUDINESS IN THE MOISTURE PLUME THURSDAY MAY MAKE IT TO THE STATE PUTTING QUESTION INTO THE NEAR 90 FORECASTED HIGHS ON THURSDAY. FOR THE TIME BEING BELIEVE THE LOWERED 850MB TEMPERATURES ARE A FLUKE AND ANTICIPATE THE WARMER RANGE IN DAYTIME HIGHS. THE ECMWF IS ONBOARD WITH SOME OF THESE IDEAS...BUT IS MORE SUBDUED IN THE END RESULT. THEREFORE...FURTHER MONITORING IS REQUIRED. HOWEVER...WILL CARRY PRECIPITATION CHANCES THROUGH SATURDAY NIGHT AS QUESTIONS IN TIMING ARE STILL VALID. MARINE... DESPITE A COLD FRONT DROPPING THROUGH LOWER MICHIGAN THIS MORNING...WINDS WILL REMAIN RELATIVELY SUBDUED. HOWEVER...A SOUTHWEST FETCH PRIOR TO FRONTAL PASSAGE WILL ALLOW WAVES TO REMAIN IN THE 2 TO 4 FOOT RANGE FOR PORTIONS OF OUTER SAGINAW BAY. TONIGHT...A DISTURBANCE ALOFT WILL BRING AN INCREASED CHANCE FOR SHOWERS AND THUNDERSTORMS BEGINNING AFTER MIDNIGHT FOR NORTHERN LAKE HURON. THIS AREA OF PRECIPITATION WILL DRIFT EAST SOUTHEASTWARD ON TUESDAY GIVING THE REMAINDER OF LAKE HURON AN INCREASED THREAT. WITH SURFACE HIGH PRESSURE PASSING TO OUR EAST...WINDS WILL INCREASE ON WEDNESDAY AS SOUTHERLY FLOW IS ESTABLISHED. AT THIS TIME...WINDS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT CONDITIONS AS WARM AIR ADVECTION SETS THE STAGE FOR A STABLE ENVIRONMENT OVER THE WATER. A STRONG LOW PRESSURE SYSTEM IS EXPECTED AT THE END OF THE WEEK BRINGING A PERIOD OF UNSETTLED WEATHER. CHANCES FOR SHOWERS AND THUNDERSTORMS ARE EXPECTED THROUGH SUNDAY MORNING. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....SF SHORT TERM...DWD LONG TERM....CB MARINE.......CB YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1058 AM EDT MON SEP 3 2007 .UPDATE... TEMPS/WINDS IN GOOD SHAPE. DID INCREASE CLOUDS A BIT QUICKER AS AREA OF H7 FGEN AND RIBBON OF H7 MOISTURE EXTENDS INTO NORTHERN SECTIONS OF UPR MI. RADAR FM MN SHOWS JUST A SMATTERING OF SHOWERS MOVING TOWARD THE ARROWHEAD CLOSE TO FRONT AT H85. MORE CONCENTRATED SHOWERS/THUNDERSTORMS ARE OCCURRING OVR SOUTHERN MANITOBA INTO ADJACENT NW ONTARIO ALONG THE H7 FRONT. ADDED SOME SLIGHT CHANCE POPS INTO WESTERN LK SUPERIOR LATE TODAY AS SHOWERS OVR MN SHIFT EASTWARD WITH INITIAL SURGE OF MID LEVEL FGEN. APPEARS THAT SOME AREAS OF CWA WILL SEE MODERATE-HEAVY RAIN OVERNIGHT INTO TUE. TROUBLE IS...THAT CORRIDOR OF HEAVIEST RAIN WILL BE CONVECTIVE AND FAIRLY NARROW. BASED ON WHERE STRONGEST H85-H7 FGEN AND THE GREATEST MOISTURE ARE EXPECTED TO COMBINE...THINK THE NORTHERN HALF OF CWA SEES THE BEST CHANCE OF RAIN. 12Z NAM SHOWS MAX QPF AXIS CENTERED IN THIS AREA...A SLIGHT NORTHWARD ADJUSTMENT TO ITS 06Z PREDECESSOR. BASED ON LATEST DATA...CURRENT GRIDS IN FINE SHAPE WITH EXPECTED COVERAGE OF PCPN TONIGHT/TUE. && .SYNOPSIS... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A STRONG TROUGH BARRELING TOWARDS THE PACIFIC NW...RIDGING EXTENDING FROM THE FOUR CORNERS UP INTO SOUTHERN ALBERTA AND SASKATCHEWAN...AND TROUGHING OVER NE ONTARIO INTO QUEBEC. WITH UPPER MICHIGAN SITUATED BETWEEN THE RIDGE AND TROUGH...CONDITIONS ARE QUIET WITH HIGH PRESSURE BUILDING IN FROM MINNESOTA AT THE SURFACE. SKIES ARE MOSTLY CLEAR WHILE DEWPOINTS AND TEMPERATURES CONTINUE TO FALL WITH THE HIGH BUILDING IN. SOME INLAND READINGS HAVE DROPPED INTO THE LOW TO MID 40S. TO THE NW...AN AREA OF HIGH AND MID LEVEL CLOUDS CAN BE SEEN SPREADING SE FROM SOUTHERN SASKATCHEWAN...SOUTHERN MANITOBA...EASTERN NORTH DAKOTA AND NORTHERN MN. RADAR IMAGERY FROM GRAND FORKS ALSO SHOWS BANDS OF LOW REFLECTIVITIES WITHIN THESE CLOUDS...THOUGH DRY LOW TO MID LEVELS SEEN ON THE 00Z BIS AND INL SOUNDINGS HAS KEPT MUCH OF THE PCPN AS VIRGA. LIGHTNING PLOTS ALSO INDICATE A FEW STRIKES...INDICATIVE OF SOME NEGATIVE EPV. IN THIS CASE AND USUAL FOR THE SUMMER...MUCH OF THE EPV IS UPRIGHT INSTABILITY DUE TO 700-500MB LAPSE RATES AROUND 7-7.5C/KM. THIS AREA OF CLOUDS IS SITUATED SOUTH OF A 90 KT JET STREAK STRETCHING FROM CENTRAL SASKATCHEWAN INTO NW ONTARIO...IN AN AREA OF 800-600MB FRONTOGENESIS...AND WELL NORTH OF A SURFACE WARM FRONT WHICH EXTENDS FROM SIOUX FALLS SOUTH DAKOTA NW TO A 1007MB LOW IN SE MONTANA. && .DISCUSSION... MAIN FORECAST CONCERN IS PCPN CHANCES/LOCATION AND HOW MUCH PCPN FOR TONIGHT AND TUE. TODAY...MUCH OF THE DAY IS EXPECTED TO BE QUIET WITH HIGH PRESSURE EVENTUALLY ENCOMPASSING MUCH OF THE CWA BY 18Z. HOWEVER...HIGH AND MID CLOUDS WILL DEFINITELY BE ON THE INCREASE AS THE 90-100 KT JET STREAK MOVES TO JET NORTH OF LAKE SUPERIOR AND MID-LEVEL FRONTOGENESIS SHIFTS EAST INTO THE U.P.. A FEW SHOWERS OR THUNDERSTORMS MAY ALSO TRY TO ENTER WESTERN LAKE SUPERIOR LATE THIS AFTERNOON WITHIN THE FRONTOGENESIS AREA AND RIGHT ENTRANCE REGION OF THE 90-100 KT JET...THUS HAVE MAINTAINED THE GOING 20 POPS. ALTHOUGH 850MB TEMPS ARE PROGGED AROUND 14C WHICH WOULD SUPPORT HIGHS IN THE LOW 80S...THE INCOMING CLOUD ALONG WITH LAKE BREEZES SHOULD KEEP TEMPERATURES A FEW DEGREES COOLER THAN THAT. TONIGHT INTO TUE...LARGE TROUGH OFF THE WEST COAST IS PROGGED TO MOVE ONSHORE DURING THIS PERIOD...FORCING RIDGING TO BUILD DOWNSTREAM OF IT ACROSS THE NORTHERN PLAINS INTO SOUTH CENTRAL CANADA. THIS BUILDING RIDGE...COMBINED WITH TYPICAL DIURNAL AFFECTS...WILL RESULT IN THE DEVELOPMENT OF A LOW LEVEL JET THIS EVENING FROM NEBRASKA UP INTO MN...LIFTING THE SURFACE WARM FRONT TOWARDS THE AREA. HOWEVER...WITH NW FLOW ALOFT...COOLER AIR OVER NORTHERN ONTARIO REMAINS STATIONARY. THE NET RESULT THEN IS TO TIGHTEN UP THE LOW LEVEL THERMAL GRADIENT ACROSS UPPER MICHIGAN... NORTHERN MN AND FAR WESTERN ONTARIO...THUS INCREASING ISENTROPIC LIFT...MID-LEVEL FRONTOGENESIS AND THE UPPER LEVEL JET. IN ADDITION...THE LOW LEVEL JET WILL HELP TO ADVECT IN NEGATIVE EPV INTO THE AREA WITH CROSS-SECTIONS SUGGESTING POTENTIAL FOR BOTH UPRIGHT AND SYMMETRIC CONVECTION. THEREFORE...A FAVORABLE RAIN SCENARIO IS SHAPING UP...PARTICULARLY AFTER MIDNIGHT INTO TUE MORNING WHEN ALL THREE ARE PROGGED TO BE JUXTAPOSED. THE 00Z GFS AND NAM HAVE SOME VERY IMPRESSIVE 12 HOUR QPF AMOUNTS FROM 06-18Z...WITH THE BROADER RESOLUTION GFS SHOWING 1-1.5 INCHES FROM THE KEWEENAW INTO CHIPPEWA COUNTY AND THE HIGHER RESOLUTION NAM SHOWING 1.5-3 INCHES FROM THE KEWEENAW INTO SCHOOLCRAFT COUNTY. IN BOTH MODELS... VERY LITTLE FALLS ALONG THE WISCONSIN BORDER AND AT THE NE END OF THE LAKE...REALLY INDICATING HOW NARROW THIS BANDING WILL END UP. COMPARE THIS TO OUR LOCAL WRF-ARW RUNS WHERE ITS QPF IT HAS THE SAME WIDTH OF PCPN...JUST SHIFTED TO THE SW ALLOWING MARQUETTE COUNTY TO GET UP TO 3 INCHES OF RAIN. THE REGIONAL CANADIAN...ON THE OTHER HAND...HAS MOST OF THE QPF OVER LAKE SUPERIOR...BUT STILL IMPACTS THE KEWEENAW AND EASTERN U.P.. FOR NOW HAVE DECIDED TO RAISE POPS UP TO 70 FOR THE NORTHERN AND EASTERN U.P. WITH QPF AMOUNTS SIMILAR TO THE GFS. BOTH POPS AND QPF WILL PROBABLY HAVE TO BE ADJUSTED SPATIALLY AND UP OR DOWN LATER TODAY (NEW 06Z NAM DEPICTS CONTINUED ISSUES WITH HIGHEST QPF AXIS NEAR WI BORDER). NO MATTER WHERE THE RAIN FALLS...IT WILL BE VERY HELPFUL. IT APPEARS THAT MUCH OF THE RAIN SHOULD BE DONE BY 18Z...WITH ONLY LIGHT SHOWERS CONTINUING TO 00Z DUE TO WEAKER MID-LEVEL FRONTOGENESIS. TUE NIGHT INTO WED...WESTERN TROUGH IS PROGGED TO CONTINUE MOVING SLOWLY EAST...REACHING EASTERN IDAHO BY 00Z THU. AS A RESULT...UPPER RIDGING OVER THE NORTHERN PLAINS WILL SHIFT OVER MICHIGAN BY 18Z WED. WARM ADVECTION UNDERNEATH THE RIDGE SHOULD LIFT THE SURFACE WARM FRONT OVER THE CWA BY 12Z WED AND THEN COMPLETELY NORTH OF THE AREA BY 00Z. WILL CONTINUE CHANCE POPS FOR THE ISENTROPIC LIFT OCCURRING NORTH OF THE WARM FRONT. ONCE THE FRONT PASSES...EXPECT SKIES TO CLEAR WITH ONLY SOME HORIZONTAL CONVECTIVE ROLL CUMULUS DURING THE DAYTIME IN THE WARM SECTOR. MODELS ARE IN GOOD AGREEMENT SHOWING 850MB TEMPS CLIMBING TO 18-20C BY 18Z WED...AND WITH A 10-15 MPH SOUTH WIND...SURFACE TEMPERATURES ARE EXPECTED TO GET QUITE WARM. MET GUIDANCE IS ALMOST 90 AT IMT. MADE ONLY SLIGHT ADJUSTMENTS TO THE GOING TEMPERATURE GRIDS. WED NIGHT INTO THU NIGHT...UPPER TROUGH IS PROGGED TO EJECT OUT INTO THE NORTHERN PLAINS IN RESPONSE TO A LARGER TROUGH DROPPING THROUGH ALBERTA. THIS TROUGH WILL SEND A COLD FRONT EASTWARD TOWARDS MINNESOTA BY 00Z FRI PER 00Z ECMWF/GFS/CANADIAN. A DRY...WARM AND HUMID WED NIGHT IS EXPECTED WITH THE AREA GENERALLY UNDER UPPER RIDGING. HOWEVER...ON THU...THE FLOW TURNS SOUTHWESTERLY. WITHIN THIS FLOW...MODELS SUGGEST A PORTION OF THE CURRENT UPPER LOW IN SOUTH TEXAS LIFTING UP ACROSS THE CWA ON THU. THUS HAVE MAINTAINED GOING CHANCE POPS AND MOSTLY CLOUDY SKIES. THESE CLOUDS SHOULD KEEP TEMPERATURES CLIMBING AS HIGH AS ON WED. BEST CHANCE FOR RAIN AT THIS TIME APPEARS TO BE ON THU NIGHT AS UPPER TROUGH AND COLD FRONT APPROACH THE CWA. THE RAIN COULD BE HEAVY TOO...GIVEN A DEEP TROPICAL CONNECTION FROM THE GULF OF MEXICO (850MB DEWPOINTS PROGGED AROUND +14C) AND UPPER LEVEL MOISTURE STREAMING NE OFF TROPICAL STORM HENRIETTE IN THE EAST PACIFIC. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... VFR CONDITIONS WILL PREVAIL TODAY WITH VERY DRY AIR ENTRENCHED BELOW 700 MB. ARRIVAL OF MID LEVEL FRONTOGENESIS TO THE N OF WARM FRONT STRETCHING ACROSS CENTRAL MN/WI WILL RESULT IN INCREASING MID CLOUDS. LOW LEVEL FLOW WILL VEER TO THE NE WITH SFC HIGH PRES MOVING THROUGH ONTARIO AND INFLUENCE OF LAKE BREEZES. SOME -SHRA/SPRINKLES MAY ARRIVE LATE TODAY OR THIS EVENING AT KCMX...BUT DRYNESS OF LOW LEVELS SUGGESTS CONDITIONS WILL REMAIN VFR. THE FGEN FORCING AND STRENGTH OF MOISTURE INFLOW WILL INCREASE LATE TONIGHT WITH A BAND OR BANDS OF SHOWERS AND A FEW EMBEDDED TSRA DEVELOPING. THE RAINFALL MAY BE HEAVY ENOUGH TO DROP CIGS/VSBY INTO THE MVFR RANGE. NO TSRA WERE MENTIONED FOR NOW GIVEN THE EXPECTED ISOLD COVERAGE OF CONVECTION AND UNCERTAINTY WHERE THE HEAVIER RAIN SHOWERS OR TSRA MAY DEVELOP. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRES WILL SLIDE ACROSS THE WESTERN GREAT LAKES TODAY AND SHIFT INTO NORTHEAST ONTARIO TUE AS LOW PRES DEVELOPS OVER THE NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY. AS A RESULT...LIGHT NORTHWEST WINDS WILL BECOME EASTERLY TONIGHT AND INCREASE TUE AS A WARM FRONT DEVELOPS OVER NORTHERN WISCONSIN. ANOTHER LOW PRESSURE TROUGH WILL DEVELOP OVER THE NORTHERN PLAINS ON WED. SOUTHERLY WINDS WILL INCREASE AHEAD OF THE LOW...WITH WINDS ON EASTERN LAKE SUPERIOR INCREASING TO 20 TO 25 KT WED INTO THU. THE TROUGH ASSOCIATED WITH THIS LOW IS EXPECTED TO CROSS LAKE SUPERIOR LATE THU NIGHT AND FRI. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JLA DISCUSSION...AJ AVIATION...KC MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 738 AM EDT MON SEP 3 2007 .AVIATION... VFR CONDITIONS CONTINUING THROUGH TONIGHT. DO EXPECT OCCASIONAL BRIEF CEILINGS AROUND 5K FEET THIS MORNING AT KMBS/KFNT WITH WEAKENING COLD FRONT MOVING IN. OTHERWISE...SCATTERED CLOUD LAYERS AROUND 45 HUNDRED AND 8K FEET TODAY...THE LOWER LAYER PARTLY OF DIURNAL ORIGIN. MID LEVEL WARM ADVECTION CEILING LAYER EXPECTED TO DEVELOP LATE TONIGHT AS MOISTURE ALOFT INCREASES IN PRESENCE OF DYNAMIC ASCENT. SURFACE WINDS 10 KNOTS OR LESS. && .PREV DISCUSSION...ISSUED 411 AM EDT MON SEP 3 2007 SHORT TERM...TODAY WEAK SURFACE COLD FRONT IS EXPECTED TO PRETTY MUCH WASH OUT AS IT SINKS SOUTHWARD THROUGH THE FORECAST AREA TODAY...BENEATH NORTHWEST FLOW ALOFT. DYNAMIC ASCENT SUPPORT EXPECTED TO BE VERY LIMITED AT BEST TODAY. LITTLE OR NO LOW TO MID LEVEL OMEGA ASCENT OR QVECTOR CONVERGENCE...WITH 305K TO 310K ISENTROPIC ASCENT SLIGHT AT BEST. MODEST SURFACE WIND CONVERGENCE TODAY THOUGH...MAINLY THIS AFTERNOON. MODEST INSTABILITY EXPECTED THIS AFTERNOON IN SOUTHERN COUNTIES AHEAD OF COLD FRONT...BUT MODEL FORECAST SOUNDINGS SHOW QUITE A BIT OF CAPPING BELOW 700 MB TO INHIBIT CONVECTION. WILL CONTINUE A DRY FORECAST TODAY...AS MODELS ALSO CONTINUE TO ADVERTISE VERY LIMITED MOISTURE. QPF AS PER MODELS FOR TODAY IS VIRTUALLY NON EXISTENT...THOUGH 4KM NMM WRF AND RUC13 GIVE A SLIGHT HINT OF A LOCAL SPRINKLE OR LIGHT SHOWER. WATER VAPOR IMAGERY SHOWS A DRYING TREND ALOFT...AND SATELLITE/METAR OVERNIGHT TRENDS OF LOW TO MID CLOUDS IN MOISTURE AXIS PRECEDING THE FRONT WOULD SUPPORT ONLY A PARTIAL CLOUD COVER TODAY. SAME TRUE OF ANY DIURNAL CUMULUS DEVELOPMENT AS PER AWIPS CUMULUS SCHEME. TEMPERATURES TODAY SHOULD REACH AROUND 80 NORTH...AND MID 80S SOUTH AS SUPPORTED BY T1 TEMPERATURES. LONG TERM...MONDAY NIGHT THROUGH SUNDAY CHALLENGES OF THE LONG TERM FORECAST CENTER ON PRECIPITATION CHANCES FOR TUESDAY/THUR-SAT. BUST POTENTIAL OF MAX TEMPERATURES FOR TUESDAY AND THURSDAY ARE ALSO A CONCERN. BY TOMORROW EVENING THE MIDLEVEL COLD FRONT AND THETA E GRADIENTS WILL BE ALIGNED NORTHWEST TO SOUTHEAST FROM NORTHERN MINNESOTA THROUGH SOUTHEASTERN MICHIGAN TO NORTHERN PENNSYLVANIA. ON THE NORTHERN PERIPHERY OF THE UPPER LEVEL RIDGE AND IN VICINITY TO MIDLEVEL THERMAL BOUNDARIES PLACES LAKE HURON AND PORTIONS OF SOUTHEASTERN LOWER IN PRIME DOWNSTREAM LOCATION OF THE MCS ACTIVITY ACROSS THE NORTHERN PLAINS/SOUTH CENTRAL CANADA. CONVECTIVE INITIATION TOMORROW AFTERNOON ACROSS LAKE WINNIPEG/NORTHERN MINNESOTA APPEARS LIKELY AS A SURFACE WARM FRONT SHARPENS IN RESPONSE TO NORTHERN PLAINS CYCLOGENESIS. A ZONAL WEST TO EAST LOW LEVEL JET REACHING 35 KNOTS WILL FORCE ANY PRECIPITATION EAST SOUTHEASTWARD THROUGHOUT THE NIGHT. DESPITE AN UNSTABLE ENVIRONMENT ACROSS THE SOURCE REGION LATEST GUIDANCE IS SHOWING NOTHING IN THE WAY OF NEGATIVE SHOWALTERS IN THIS AREA AND IS EVEN HAVING A DIFFICULT TIME GENERATING CONVECTIVE PRECIPITATION. ATTM...BELIEVE THE BULK OF THE PRECIPITATION ACROSS THE NORTH (STARTING AFTER MIDNIGHT) AND LASTING FOR A BETTER PART OF THE DAY WILL BE STRATIFORM IN NATURE WITH A FEW LIGHTNING STRIKES POSSIBLE. THE PRECIPITATION CHANCES WILL MAINLY BE FOR LAKE HURON...BUT PORTIONS OF THE THUMB AND SAGINAW RIVER VALLEY WILL HAVE A SHOT FOR SOME RAINFALL MAINLY DURING THE DAYLIGHT ON TUESDAY. THE TUESDAY TEMPERATURE FORECAST FOR THIS ISSUANCE IS ON THE COLD SIDE WITH THE ANTICIPATED CLOUD COVER...SO ANY THINNING OR BREAKS TO THE CANOPY COULD SEND TEMPERATURES UPWARD. THE MIDLEVEL WARM FRONT SURGES NORTHWARD UNDER RAPIDLY AMPLIFYING UPPER LEVELS ON WEDNESDAY. HIGH TEMPERATURES ON WEDNESDAY ARE EXPECTED TO BE IN THE MID TO UPPER 80S IN INCREASING SOUTHWESTERLY FLOW. THE LATEST 00Z GFS IS BACK TO THE MAJOR PHASING/STRONG SURFACE CYCLOGENESIS EVENT BEGINNING ON THURSDAY. THE PRIMARY PLAYERS AGAIN ARE THE QUASI-CUTOFF ENERGY OVER THE GREAT BASIN...SOME DISORGANIZED WAVE ENERGY SURGING NORTHWARD OUT OF WESTERN TEXAS...AND THE STRONG DYNAMIC WAVE CRASHING ONSHORE OFF THE PACIFIC WEDNESDAY NIGHT. RISING HEIGHTS ACROSS THE EAST SHOULD BLOCK THE WESTERLY FLOW ENOUGH ALLOWING FOR THE REASONABLE SOLUTION OF PHASING AND RESULTANT DEEPENING. PLENTY OF TIME REMAINS TO REFINE THE FORECAST FOR THIS SYSTEM BUT HAVE DECIDED ON INSERTING POPS ONCE AGAIN FOR THURSDAY NIGHT. THE ADVERTISED STRONG TO INTENSE HEIGHT FALLS ACROSS THE UPPER MIDWEST WOULD ALLOW FOR THE QUICK GENERATION OF A STRONG SOUTHERLY LOW LEVEL JET AND ASSOCIATED MOISTURE SURGE. EMBEDDED SHORTWAVES IN THE SOUTHERLY FLOW SHOULD ALLOW FOR ENOUGH SYNOPTIC SUPPORT IN GENERAL ISENTROPIC REGIME TO GENERATE SHOWERS AND THUNDERSTORMS THURSDAY NIGHT. UPPER LEVEL CIRRUS AND DEBRIS CLOUDINESS IN THE MOISTURE PLUME THURSDAY MAY MAKE IT TO THE STATE PUTTING QUESTION INTO THE NEAR 90 FORECASTED HIGHS ON THURSDAY. FOR THE TIME BEING BELIEVE THE LOWERED 850MB TEMPERATURES ARE A FLUKE AND ANTICIPATE THE WARMER RANGE IN DAYTIME HIGHS. THE ECMWF IS ONBOARD WITH SOME OF THESE IDEAS...BUT IS MORE SUBDUED IN THE END RESULT. THEREFORE...FURTHER MONITORING IS REQUIRED. HOWEVER...WILL CARRY PRECIPITATION CHANCES THROUGH SATURDAY NIGHT AS QUESTIONS IN TIMING ARE STILL VALID. MARINE... DESPITE A COLD FRONT DROPPING THROUGH LOWER MICHIGAN THIS MORNING...WINDS WILL REMAIN RELATIVELY SUBDUED. HOWEVER...A SOUTHWEST FETCH PRIOR TO FRONTAL PASSAGE WILL ALLOW WAVES TO REMAIN IN THE 2 TO 4 FOOT RANGE FOR PORTIONS OF OUTER SAGINAW BAY. TONIGHT...A DISTURBANCE ALOFT WILL BRING AN INCREASED CHANCE FOR SHOWERS AND THUNDERSTORMS BEGINNING AFTER MIDNIGHT FOR NORTHERN LAKE HURON. THIS AREA OF PRECIPITATION WILL DRIFT EAST SOUTHEASTWARD ON TUESDAY GIVING THE REMAINDER OF LAKE HURON AN INCREASED THREAT. WITH SURFACE HIGH PRESSURE PASSING TO OUR EAST...WINDS WILL INCREASE ON WEDNESDAY AS SOUTHERLY FLOW IS ESTABLISHED. AT THIS TIME...WINDS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT CONDITIONS AS WARM AIR ADVECTION SETS THE STAGE FOR A STABLE ENVIRONMENT OVER THE WATER. A STRONG LOW PRESSURE SYSTEM IS EXPECTED AT THE END OF THE WEEK BRINGING A PERIOD OF UNSETTLED WEATHER. CHANCES FOR SHOWERS AND THUNDERSTORMS ARE EXPECTED THROUGH SUNDAY MORNING. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....DWD SHORT TERM...DWD LONG TERM....CB MARINE.......CB YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION...UPDATED FOR AVIATION NATIONAL WEATHER SERVICE MARQUETTE MI 735 AM EDT MON SEP 3 2007 .SYNOPSIS... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A STRONG TROUGH BARRELING TOWARDS THE PACIFIC NW...RIDGING EXTENDING FROM THE FOUR CORNERS UP INTO SOUTHERN ALBERTA AND SASKATCHEWAN...AND TROUGHING OVER NE ONTARIO INTO QUEBEC. WITH UPPER MICHIGAN SITUATED BETWEEN THE RIDGE AND TROUGH...CONDITIONS ARE QUIET WITH HIGH PRESSURE BUILDING IN FROM MINNESOTA AT THE SURFACE. SKIES ARE MOSTLY CLEAR WHILE DEWPOINTS AND TEMPERATURES CONTINUE TO FALL WITH THE HIGH BUILDING IN. SOME INLAND READINGS HAVE DROPPED INTO THE LOW TO MID 40S. TO THE NW...AN AREA OF HIGH AND MID LEVEL CLOUDS CAN BE SEEN SPREADING SE FROM SOUTHERN SASKATCHEWAN...SOUTHERN MANITOBA...EASTERN NORTH DAKOTA AND NORTHERN MN. RADAR IMAGERY FROM GRAND FORKS ALSO SHOWS BANDS OF LOW REFLECTIVITIES WITHIN THESE CLOUDS...THOUGH DRY LOW TO MID LEVELS SEEN ON THE 00Z BIS AND INL SOUNDINGS HAS KEPT MUCH OF THE PCPN AS VIRGA. LIGHTNING PLOTS ALSO INDICATE A FEW STRIKES...INDICATIVE OF SOME NEGATIVE EPV. IN THIS CASE AND USUAL FOR THE SUMMER...MUCH OF THE EPV IS UPRIGHT INSTABILITY DUE TO 700-500MB LAPSE RATES AROUND 7-7.5C/KM. THIS AREA OF CLOUDS IS SITUATED SOUTH OF A 90 KT JET STREAK STRETCHING FROM CENTRAL SASKATCHEWAN INTO NW ONTARIO...IN AN AREA OF 800-600MB FRONTOGENESIS...AND WELL NORTH OF A SURFACE WARM FRONT WHICH EXTENDS FROM SIOUX FALLS SOUTH DAKOTA NW TO A 1007MB LOW IN SE MONTANA. && .DISCUSSION... MAIN FORECAST CONCERN IS PCPN CHANCES/LOCATION AND HOW MUCH PCPN FOR TONIGHT AND TUE. TODAY...MUCH OF THE DAY IS EXPECTED TO BE QUIET WITH HIGH PRESSURE EVENTUALLY ENCOMPASSING MUCH OF THE CWA BY 18Z. HOWEVER...HIGH AND MID CLOUDS WILL DEFINITELY BE ON THE INCREASE AS THE 90-100 KT JET STREAK MOVES TO JET NORTH OF LAKE SUPERIOR AND MID-LEVEL FRONTOGENESIS SHIFTS EAST INTO THE U.P.. A FEW SHOWERS OR THUNDERSTORMS MAY ALSO TRY TO ENTER WESTERN LAKE SUPERIOR LATE THIS AFTERNOON WITHIN THE FRONTOGENESIS AREA AND RIGHT ENTRANCE REGION OF THE 90-100 KT JET...THUS HAVE MAINTAINED THE GOING 20 POPS. ALTHOUGH 850MB TEMPS ARE PROGGED AROUND 14C WHICH WOULD SUPPORT HIGHS IN THE LOW 80S...THE INCOMING CLOUD ALONG WITH LAKE BREEZES SHOULD KEEP TEMPERATURES A FEW DEGREES COOLER THAN THAT. TONIGHT INTO TUE...LARGE TROUGH OFF THE WEST COAST IS PROGGED TO MOVE ONSHORE DURING THIS PERIOD...FORCING RIDGING TO BUILD DOWNSTREAM OF IT ACROSS THE NORTHERN PLAINS INTO SOUTH CENTRAL CANADA. THIS BUILDING RIDGE...COMBINED WITH TYPICAL DIURNAL AFFECTS...WILL RESULT IN THE DEVELOPMENT OF A LOW LEVEL JET THIS EVENING FROM NEBRASKA UP INTO MN...LIFTING THE SURFACE WARM FRONT TOWARDS THE AREA. HOWEVER...WITH NW FLOW ALOFT...COOLER AIR OVER NORTHERN ONTARIO REMAINS STATIONARY. THE NET RESULT THEN IS TO TIGHTEN UP THE LOW LEVEL THERMAL GRADIENT ACROSS UPPER MICHIGAN... NORTHERN MN AND FAR WESTERN ONTARIO...THUS INCREASING ISENTROPIC LIFT...MID-LEVEL FRONTOGENESIS AND THE UPPER LEVEL JET. IN ADDITION...THE LOW LEVEL JET WILL HELP TO ADVECT IN NEGATIVE EPV INTO THE AREA WITH CROSS-SECTIONS SUGGESTING POTENTIAL FOR BOTH UPRIGHT AND SYMMETRIC CONVECTION. THEREFORE...A FAVORABLE RAIN SCENARIO IS SHAPING UP...PARTICULARLY AFTER MIDNIGHT INTO TUE MORNING WHEN ALL THREE ARE PROGGED TO BE JUXTAPOSED. THE 00Z GFS AND NAM HAVE SOME VERY IMPRESSIVE 12 HOUR QPF AMOUNTS FROM 06-18Z...WITH THE BROADER RESOLUTION GFS SHOWING 1-1.5 INCHES FROM THE KEWEENAW INTO CHIPPEWA COUNTY AND THE HIGHER RESOLUTION NAM SHOWING 1.5-3 INCHES FROM THE KEWEENAW INTO SCHOOLCRAFT COUNTY. IN BOTH MODELS... VERY LITTLE FALLS ALONG THE WISCONSIN BORDER AND AT THE NE END OF THE LAKE...REALLY INDICATING HOW NARROW THIS BANDING WILL END UP. COMPARE THIS TO OUR LOCAL WRF-ARW RUNS WHERE ITS QPF IT HAS THE SAME WIDTH OF PCPN...JUST SHIFTED TO THE SW ALLOWING MARQUETTE COUNTY TO GET UP TO 3 INCHES OF RAIN. THE REGIONAL CANADIAN...ON THE OTHER HAND...HAS MOST OF THE QPF OVER LAKE SUPERIOR...BUT STILL IMPACTS THE KEWEENAW AND EASTERN U.P.. FOR NOW HAVE DECIDED TO RAISE POPS UP TO 70 FOR THE NORTHERN AND EASTERN U.P. WITH QPF AMOUNTS SIMILAR TO THE GFS. BOTH POPS AND QPF WILL PROBABLY HAVE TO BE ADJUSTED SPATIALLY AND UP OR DOWN LATER TODAY (NEW 06Z NAM DEPICTS CONTINUED ISSUES WITH HIGHEST QPF AXIS NEAR WI BORDER). NO MATTER WHERE THE RAIN FALLS...IT WILL BE VERY HELPFUL. IT APPEARS THAT MUCH OF THE RAIN SHOULD BE DONE BY 18Z...WITH ONLY LIGHT SHOWERS CONTINUING TO 00Z DUE TO WEAKER MID-LEVEL FRONTOGENESIS. TUE NIGHT INTO WED...WESTERN TROUGH IS PROGGED TO CONTINUE MOVING SLOWLY EAST...REACHING EASTERN IDAHO BY 00Z THU. AS A RESULT...UPPER RIDGING OVER THE NORTHERN PLAINS WILL SHIFT OVER MICHIGAN BY 18Z WED. WARM ADVECTION UNDERNEATH THE RIDGE SHOULD LIFT THE SURFACE WARM FRONT OVER THE CWA BY 12Z WED AND THEN COMPLETELY NORTH OF THE AREA BY 00Z. WILL CONTINUE CHANCE POPS FOR THE ISENTROPIC LIFT OCCURRING NORTH OF THE WARM FRONT. ONCE THE FRONT PASSES...EXPECT SKIES TO CLEAR WITH ONLY SOME HORIZONTAL CONVECTIVE ROLL CUMULUS DURING THE DAYTIME IN THE WARM SECTOR. MODELS ARE IN GOOD AGREEMENT SHOWING 850MB TEMPS CLIMBING TO 18-20C BY 18Z WED...AND WITH A 10-15 MPH SOUTH WIND...SURFACE TEMPERATURES ARE EXPECTED TO GET QUITE WARM. MET GUIDANCE IS ALMOST 90 AT IMT. MADE ONLY SLIGHT ADJUSTMENTS TO THE GOING TEMPERATURE GRIDS. WED NIGHT INTO THU NIGHT...UPPER TROUGH IS PROGGED TO EJECT OUT INTO THE NORTHERN PLAINS IN RESPONSE TO A LARGER TROUGH DROPPING THROUGH ALBERTA. THIS TROUGH WILL SEND A COLD FRONT EASTWARD TOWARDS MINNESOTA BY 00Z FRI PER 00Z ECMWF/GFS/CANADIAN. A DRY...WARM AND HUMID WED NIGHT IS EXPECTED WITH THE AREA GENERALLY UNDER UPPER RIDGING. HOWEVER...ON THU...THE FLOW TURNS SOUTHWESTERLY. WITHIN THIS FLOW...MODELS SUGGEST A PORTION OF THE CURRENT UPPER LOW IN SOUTH TEXAS LIFTING UP ACROSS THE CWA ON THU. THUS HAVE MAINTAINED GOING CHANCE POPS AND MOSTLY CLOUDY SKIES. THESE CLOUDS SHOULD KEEP TEMPERATURES CLIMBING AS HIGH AS ON WED. BEST CHANCE FOR RAIN AT THIS TIME APPEARS TO BE ON THU NIGHT AS UPPER TROUGH AND COLD FRONT APPROACH THE CWA. THE RAIN COULD BE HEAVY TOO...GIVEN A DEEP TROPICAL CONNECTION FROM THE GULF OF MEXICO (850MB DEWPOINTS PROGGED AROUND +14C) AND UPPER LEVEL MOISTURE STREAMING NE OFF TROPICAL STORM HENRIETTE IN THE EAST PACIFIC. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... VFR CONDITIONS WILL PREVAIL TODAY WITH VERY DRY AIR ENTRENCHED BELOW 700 MB. ARRIVAL OF MID LEVEL FRONTOGENESIS TO THE N OF WARM FRONT STRETCHING ACROSS CENTRAL MN/WI WILL RESULT IN INCREASING MID CLOUDS. LOW LEVEL FLOW WILL VEER TO THE NE WITH SFC HIGH PRES MOVING THROUGH ONTARIO AND INFLUENCE OF LAKE BREEZES. SOME -SHRA/SPRINKLES MAY ARRIVE LATE TODAY OR THIS EVENING AT KCMX...BUT DRYNESS OF LOW LEVELS SUGGESTS CONDITIONS WILL REMAIN VFR. THE FGEN FORCING AND STRENGTH OF MOISTURE INFLOW WILL INCREASE LATE TONIGHT WITH A BAND OR BANDS OF SHOWERS AND A FEW EMBEDDED TSRA DEVELOPING. THE RAINFALL MAY BE HEAVY ENOUGH TO DROP CIGS/VSBY INTO THE MVFR RANGE. NO TSRA WERE MENTIONED FOR NOW GIVEN THE EXPECTED ISOLD COVERAGE OF CONVECTION AND UNCERTAINTY WHERE THE HEAVIER RAIN SHOWERS OR TSRA MAY DEVELOP. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRES WILL SLIDE ACROSS THE WESTERN GREAT LAKES TODAY AND SHIFT INTO NORTHEAST ONTARIO TUE AS LOW PRES DEVELOPS OVER THE NORTHERN PLAINS INTO THE UPPER MISSISSIPPI VALLEY. AS A RESULT...LIGHT NORTHWEST WINDS WILL BECOME EASTERLY TONIGHT AND INCREASE TUE AS A WARM FRONT DEVELOPS OVER NORTHERN WISCONSIN. ANOTHER LOW PRESSURE TROUGH WILL DEVELOP OVER THE NORTHERN PLAINS ON WED. SOUTHERLY WINDS WILL INCREASE AHEAD OF THE LOW...WITH WINDS ON EASTERN LAKE SUPERIOR INCREASING TO 20 TO 25 KT WED INTO THU. THE TROUGH ASSOCIATED WITH THIS LOW IS EXPECTED TO CROSS LAKE SUPERIOR LATE THU NIGHT AND FRI. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...AJ AVIATION...KC MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 411 AM EDT MON SEP 3 2007 .SHORT TERM...TODAY WEAK SURFACE COLD FRONT IS EXPECTED TO PRETTY MUCH WASH OUT AS IT SINKS SOUTHWARD THROUGH THE FORECAST AREA TODAY...BENEATH NORTHWEST FLOW ALOFT. DYNAMIC ASCENT SUPPORT EXPECTED TO BE VERY LIMITED AT BEST TODAY. LITTLE OR NO LOW TO MID LEVEL OMEGA ASCENT OR QVECTOR CONVERGENCE...WITH 305K TO 310K ISENTROPIC ASCENT SLIGHT AT BEST. MODEST SURFACE WIND CONVERGENCE TODAY THOUGH...MAINLY THIS AFTERNOON. MODEST INSTABILITY EXPECTED THIS AFTERNOON IN SOUTHERN COUNTIES AHEAD OF COLD FRONT...BUT MODEL FORECAST SOUNDINGS SHOW QUITE A BIT OF CAPPING BELOW 700 MB TO INHIBIT CONVECTION. WILL CONTINUE A DRY FORECAST TODAY...AS MODELS ALSO CONTINUE TO ADVERTISE VERY LIMITED MOISTURE. QPF AS PER MODELS FOR TODAY IS VIRTUALLY NON EXISTENT...THOUGH 4KM NMM WRF AND RUC13 GIVE A SLIGHT HINT OF A LOCAL SPRINKLE OR LIGHT SHOWER. WATER VAPOR IMAGERY SHOWS A DRYING TREND ALOFT...AND SATELLITE/METAR OVERNIGHT TRENDS OF LOW TO MID CLOUDS IN MOISTURE AXIS PRECEDING THE FRONT WOULD SUPPORT ONLY A PARTIAL CLOUD COVER TODAY. SAME TRUE OF ANY DIURNAL CUMULUS DEVELOPMENT AS PER AWIPS CUMULUS SCHEME. TEMPERATURES TODAY SHOULD REACH AROUND 80 NORTH...AND MID 80S SOUTH AS SUPPORTED BY T1 TEMPERATURES. && .LONG TERM...MONDAY NIGHT THROUGH SUNDAY CHALLENGES OF THE LONG TERM FORECAST CENTER ON PRECIPITATION CHANCES FOR TUESDAY/THUR-SAT. BUST POTENTIAL OF MAX TEMPERATURES FOR TUESDAY AND THURSDAY ARE ALSO A CONCERN. BY TOMORROW EVENING THE MIDLEVEL COLD FRONT AND THETA E GRADIENTS WILL BE ALIGNED NORTHWEST TO SOUTHEAST FROM NORTHERN MINNESOTA THROUGH SOUTHEASTERN MICHIGAN TO NORTHERN PENNSYLVANIA. ON THE NORTHERN PERIPHERY OF THE UPPER LEVEL RIDGE AND IN VICINITY TO MIDLEVEL THERMAL BOUNDARIES PLACES LAKE HURON AND PORTIONS OF SOUTHEASTERN LOWER IN PRIME DOWNSTREAM LOCATION OF THE MCS ACTIVITY ACROSS THE NORTHERN PLAINS/SOUTH CENTRAL CANADA. CONVECTIVE INITIATION TOMORROW AFTERNOON ACROSS LAKE WINNIPEG/NORTHERN MINNESOTA APPEARS LIKELY AS A SURFACE WARM FRONT SHARPENS IN RESPONSE TO NORTHERN PLAINS CYCLOGENESIS. A ZONAL WEST TO EAST LOW LEVEL JET REACHING 35 KNOTS WILL FORCE ANY PRECIPITATION EAST SOUTHEASTWARD THROUGHOUT THE NIGHT. DESPITE AN UNSTABLE ENVIRONMENT ACROSS THE SOURCE REGION LATEST GUIDANCE IS SHOWING NOTHING IN THE WAY OF NEGATIVE SHOWALTERS IN THIS AREA AND IS EVEN HAVING A DIFFICULT TIME GENERATING CONVECTIVE PRECIPITATION. ATTM...BELIEVE THE BULK OF THE PRECIPITATION ACROSS THE NORTH (STARTING AFTER MIDNIGHT) AND LASTING FOR A BETTER PART OF THE DAY WILL BE STRATIFORM IN NATURE WITH A FEW LIGHTNING STRIKES POSSIBLE. THE PRECIPITATION CHANCES WILL MAINLY BE FOR LAKE HURON...BUT PORTIONS OF THE THUMB AND SAGINAW RIVER VALLEY WILL HAVE A SHOT FOR SOME RAINFALL MAINLY DURING THE DAYLIGHT ON TUESDAY. THE TUESDAY TEMPERATURE FORECAST FOR THIS ISSUANCE IS ON THE COLD SIDE WITH THE ANTICIPATED CLOUD COVER...SO ANY THINNING OR BREAKS TO THE CANOPY COULD SEND TEMPERATURES UPWARD. THE MIDLEVEL WARM FRONT SURGES NORTHWARD UNDER RAPIDLY AMPLIFYING UPPER LEVELS ON WEDNESDAY. HIGH TEMPERATURES ON WEDNESDAY ARE EXPECTED TO BE IN THE MID TO UPPER 80S IN INCREASING SOUTHWESTERLY FLOW. THE LATEST 00Z GFS IS BACK TO THE MAJOR PHASING/STRONG SURFACE CYCLOGENESIS EVENT BEGINNING ON THURSDAY. THE PRIMARY PLAYERS AGAIN ARE THE QUASI-CUTOFF ENERGY OVER THE GREAT BASIN...SOME DISORGANIZED WAVE ENERGY SURGING NORTHWARD OUT OF WESTERN TEXAS...AND THE STRONG DYNAMIC WAVE CRASHING ONSHORE OFF THE PACIFIC WEDNESDAY NIGHT. RISING HEIGHTS ACROSS THE EAST SHOULD BLOCK THE WESTERLY FLOW ENOUGH ALLOWING FOR THE REASONABLE SOLUTION OF PHASING AND RESULTANT DEEPENING. PLENTY OF TIME REMAINS TO REFINE THE FORECAST FOR THIS SYSTEM BUT HAVE DECIDED ON INSERTING POPS ONCE AGAIN FOR THURSDAY NIGHT. THE ADVERTISED STRONG TO INTENSE HEIGHT FALLS ACROSS THE UPPER MIDWEST WOULD ALLOW FOR THE QUICK GENERATION OF A STRONG SOUTHERLY LOW LEVEL JET AND ASSOCIATED MOISTURE SURGE. EMBEDDED SHORTWAVES IN THE SOUTHERLY FLOW SHOULD ALLOW FOR ENOUGH SYNOPTIC SUPPORT IN GENERAL ISENTROPIC REGIME TO GENERATE SHOWERS AND THUNDERSTORMS THURSDAY NIGHT. UPPER LEVEL CIRRUS AND DEBRIS CLOUDINESS IN THE MOISTURE PLUME THURSDAY MAY MAKE IT TO THE STATE PUTTING QUESTION INTO THE NEAR 90 FORECASTED HIGHS ON THURSDAY. FOR THE TIME BEING BELIEVE THE LOWERED 850MB TEMPERATURES ARE A FLUKE AND ANTICIPATE THE WARMER RANGE IN DAYTIME HIGHS. THE ECMWF IS ONBOARD WITH SOME OF THESE IDEAS...BUT IS MORE SUBDUED IN THE END RESULT. THEREFORE...FURTHER MONITORING IS REQUIRED. HOWEVER...WILL CARRY PRECIPITATION CHANCES THROUGH SATURDAY NIGHT AS QUESTIONS IN TIMING ARE STILL VALID. && .MARINE... DESPITE A COLD FRONT DROPPING THROUGH LOWER MICHIGAN THIS MORNING...WINDS WILL REMAIN RELATIVELY SUBDUED. HOWEVER...A SOUTHWEST FETCH PRIOR TO FRONTAL PASSAGE WILL ALLOW WAVES TO REMAIN IN THE 2 TO 4 FOOT RANGE FOR PORTIONS OF OUTER SAGINAW BAY. TONIGHT...A DISTURBANCE ALOFT WILL BRING AN INCREASED CHANCE FOR SHOWERS AND THUNDERSTORMS BEGINNING AFTER MIDNIGHT FOR NORTHERN LAKE HURON. THIS AREA OF PRECIPITATION WILL DRIFT EAST SOUTHEASTWARD ON TUESDAY GIVING THE REMAINDER OF LAKE HURON AN INCREASED THREAT. WITH SURFACE HIGH PRESSURE PASSING TO OUR EAST...WINDS WILL INCREASE ON WEDNESDAY AS SOUTHERLY FLOW IS ESTABLISHED. AT THIS TIME...WINDS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT CONDITIONS AS WARM AIR ADVECTION SETS THE STAGE FOR A STABLE ENVIRONMENT OVER THE WATER. A STRONG LOW PRESSURE SYSTEM IS EXPECTED AT THE END OF THE WEEK BRINGING A PERIOD OF UNSETTLED WEATHER. CHANCES FOR SHOWERS AND THUNDERSTORMS ARE EXPECTED THROUGH SUNDAY MORNING. && .PREV DISCUSSION...ISSUED 110 AM EDT MON SEP 3 2007 AVIATION... VFR CONDITIONS WILL PERSIST IN SE MICHIGAN DESPITE A COLD FRONT THAT WILL MOVE THROUGH THE REGION DURING THE MORNING AND EARLY AFTERNOON. THERE WILL BE SOME PATCHES OF MID LEVEL CLOUDS ALONG AND AHEAD OF THIS WEAK BOUNDARY AND A MODEST WIND SHIFT TOWARD THE NORTHWEST, BUT IT IS TOO DRY FOR ANY PRECIPITATION. EXPECT THE FRONT TO REACH MBS AROUND SUNRISE AND SLOWLY WORK SOUTHWARD TO DETROIT BY EARLY AFTERNOON WHILE WASHING OUT DURING PEAK HEATING. WIND SPEED WILL BE MODEST IN AVERAGING 10 KNOTS OR LESS THROUGH THE PERIOD WITH THE STRONGEST WINDS LIKELY TO OCCUR THIS EVENING AS THE WINDS BECOME FROM THE NORTHEAST OFF OF LAKE HURON. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...DWD LONG TERM....CB MARINE.......CB AVIATION.....BT YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION...UPDATED FOR AVIATION NATIONAL WEATHER SERVICE MARQUETTE MI 125 AM EDT MON SEP 3 2007 DISCUSSION...THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR RAIN ON LABOR DAY. WATER VAPOR IMAGERY AND RUC SHOWING A LOW OVER HUDSON BAY...A FLATTEN RIDGE OVER CANADIAN PRAIRIES AND A LONG WAVE TROUGH OFF THE WEST COAST OF THE PACIFIC NORTHWEST. WEAK SHORTWAVE TRAVERSING THIS RIDGE ARE MOVING THROUGH THE FORECAST AREA AND ARE OVER SOUTHERN MANITOBA. A COLD FRONT STRETCHES FROM EAST CENTRAL ONTARIO THROUGH NORTH CENTRAL U.P. INTO CENTRAL WISCONSIN. ISOLATED SHOWERS AND THUNDERSTORMS FIRED OVER EASTERN LAKE SUPERIOR THIS AFTERNOON IN ASSOCIATION WITH THE FRONT SYSTEM AND WHERE THERE IS NOT AS MUCH OF A CAP AS OVER THE LAND MASS. THE WEAK SHORTWAVE OVER THE FORECAST AREA WILL SHIFT TO SOUTHEAST LOWER MICHIGAN TONIGHT. ANOTHER SHORTWAVE WILL RACE ACROSS CENTRAL AND EASTERN LAKE SUPERIOR. DRY COOL AIR ADVECTING INTO THE AREA BEHIND THE FRONT WILL CLEAR THE SKIES OVER THE AREA. RADIATIONAL COOLING AND COLD AIR ADVECTION SHOULD PUSH TEMPERATURES DOWN INTO THE MID 40S ACROSS THE WESTERN PART OF THE CWAS AND ONLY INTO THE MID 50S EAST. THE RIDGE WILL BUILD A LITTLE ON MONDAY WHILE THE MID LEVEL LOW OVER HUDSON BAY MOVES INTO CENTRAL QUEBEC. GFS/ECMWF/NAM SHOW WEAK SHORTWAVES SLIDING DOWN THE LEE OF THIS RIDGE AND THROUGH LAKE SUPERIOR. THE COLD FRONT WILL CONTINUE TO TRACK INTO THE OHIO RIVER VALLEY...WHILE A 1015MB HIGH FLOATS INTO THE UPPER GREAT LAKES REGION. TO THE WEST ANOTHER LOW WITH AN ACCOMPANYING COLD FRONT WILL DEVELOP OVER THE NORTHERN PLAINS. DEEP MOISTURE WILL SHIFT OUT OF CENTRAL CANADA INTO NORTHERN LAKE SUPERIOR BY LATE AFTERNOON. DRIER AIR AND STABLE CONDITIONS ACCOMPANY THE SURFACE HIGH. THUS CONDITIONS LOOK DRY FOR THE FORECAST AREA...EXCEPT FOR CENTRAL AND EASTERN LAKE SUPERIOR. THE MID LEVEL RIDGE WILL BUILD INTO SASKATCHEWAN MONDAY NIGHT. SHORTWAVES RIDING DOWN THE LEE OF THIS RIDGE WILL SHIFT ACROSS CENTRAL ONTARIO INTO LAKE SUPERIOR AS ANOTHER SHORTWAVE DIGS OVER MANITOBA. A WARM FRONT WILL BUILD OUT AHEAD OF THE LOW OVER THE DAKOTAS AND MOVE INTO SOUTHERN WISCONSIN. THE HIGH OVER THE FORECAST AREA WILL MIGRATE TO THE NORTHEAST INTO NORTHEAST ONTARIO. ISENTROPIC ACCENT NORTH OF THE WARM FRONT AND DEEP MOISTURE WILL SPREAD OVER THE FORECAST AREA MONDAY NIGHT. THE EXIT REGION OF AN UPPER LEVEL JET MAX WILL SWEEP ACROSS THE FORECAST AREA. THUS THE CHANCE OF SHOWERS AND THUNDERSTORMS SHOULD CONTINUE ACROSS THE AREA. ANOTHER MID LEVEL LOW WILL RELOCATE OUT OF CENTRAL CANADA INTO HUDSON BAY ON TUESDAY. THE RIDGE WILL BUILD A LITTLE OVER MANITOBA...WHILE THE PACIFIC LOW MOVES ASHORE IN THE VICINITY OF THE PACIFIC NORTHWEST. WEAK SHORTWAVES WILL SLIDE ACROSS THE U.P. AND LAKE SUPERIOR. MEANWHILE...THE WARM FRONT WILL REMAIN NEARLY STATIONARY OVER WISCONSIN...WHILE THE ISENTROPIC ASCENT OVER THE FORECAST AREA WILL BE WEAKEN. THE UPPER LEVEL JET WILL MOVE EAST. THUS THE CHANCE OF SHOWERS WILL LESSEN OVER THE AREA ON TUESDAY. THESE IS STILL ENOUGH INSTABILITY DUE TO MID LEVEL SHORTWAVE OVER LAKE SUPERIOR TO MAINTAIN A CHANCE OF THUNDER WITH ANY RAINS THAT DEVELOP. THE WEAK SHORTWAVE WILL MOVE OUT OF THE FORECAST AREA TUESDAY NIGHT. THE WARM FRONT WILL CONTINUE TO BE WEAK. ISENTROPIC ASCENT NORTH OF THE FRONT WILL GENERATE A FEW SHOWERS AND THUNDERSTORMS OVERNIGHT. DRY AIR WILL SPREAD INTO THE AREA SO WILL END THE SHOWERS. DRY AIR WILL REMAIN IN PLACE THROUGH WEDNESDAY. A PAIR OF WEAK SHORTWAVE WILL PASS THROUGH THE AREA. WEAK ISENTROPIC ASCENT AND Q-VECTOR ENERGY WILL SWEEP THROUGH THE AREA ON WEDNESDAY. HOWEVER...WITH THE DRY CONDITIONS...IT IS QUESTIONABLE IF THERE WILL BE ENOUGH MOISTURE TO FEED ANY SHOWERS. THUS WILL KEEP ONLY LOW POPS IN PLACE. THE SHORTWAVE WILL DEEPEN OVER SOUTH CENTRAL CANADA WEDNESDAY NIGHT AND MOVE TO EASTERN SASKATCHEWAN. A WEAK SHORTWAVE WILL SWEEP THROUGH THE FORECAST AREA ON THURSDAY AS A DEEPER TROUGH MOVES INTO WESTERN MINNESOTA. THE COLD FRONT WILL MOVE INTO CENTRAL MINNESOTA BY LATE THURSDAY. ISENTROPIC ASCENT AHEAD OF THE FRONTAL SYSTEM WILL INCREASE CLOUD COVER AND A CHANCE OF SHOWERS AND THUNDERSTORMS SPREADING ACROSS THE U.P. ON THURSDAY. GFS SHOWING THE SHORTWAVE WILL DEEPEN AS IT MOVES THROUGH THE FORECAST AREA ON FRIDAY WHILE ECMWF CONTINUES TO KEEP THIS SHORTWAVE WEAK. BOTH MODELS AGREE THE FRONT WILL MOVE INTO THE WESTERN U.P. BY FRIDAY MORNING AND TO EASTERN ONTARIO AND NORTHERN LOWER FRIDAY AFTERNOON. ISENTROPIC ASCENT...ACCOMPANYING DEEP MOISTURE AND INSTABILITY WILL GENERATE SHOWERS AND THUNDERSTORMS THURSDAY NIGHT AND FRIDAY ACROSS THE AREA. THE SHORTWAVES WILL WEAKEN AND SHIFT EAST FRIDAY NIGHT AND SATURDAY. ECMWF IN MAJOR DISAGREEMENT ON POSITION OF THE FRONT BY 00Z SUNDAY. ECMWF CALLS FOR THE FRONT TO WASHOUT AND A SECONDARY FRONT TO DEVELOP OVER THE AREA AND A HIGH CENTER BUILDING OVER SASKATCHEWAN. WHEREAS...GFS BUILDS A HIGH OVER THE UPPER GREAT LAKES REGION PUSHING THE FRONT THROUGH THE UPPER GREAT LAKES. NCEP ENSEMBLE AGREES WITH GFS ON THE FRONTAL POSITION...BUT HAS THE HIGH A LITTLE FARTHER WEST OVER MANITOBA. BECAUSE OF THE UNCERTAINTY...WILL GO WITH THE HPC GUIDANCE AND FAVOR THE FLATTER ENSEMBLE SOLUTION FRIDAY NIGHT THROUGH SUNDAY. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... VFR CONDITIONS WL PREVAIL THRU THE FCST PD WITH INFLUX OF VERY DRY AIR TO THE NW. ARRIVAL OF MID LVL FGEN TMRW TO THE N OF WARM FNT STRETCHING ACRS CNTRL MN/WI WL RESULT IN INCRSG MID CLD AS LLVL FLOW VEERS TO THE NE WITH SFC HI PRES MOVING THRU ONTARIO AND LK BREEZE INFLUENCE. SOME SHRA MAY ARRIVE TMRW EVNG AT CMX...BUT DRYNESS OF LLVLS SUGS CONDITIONS WL REMAIN VFR. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... SW WINDS TO 25 KT WILL SHIFT NW THIS EVENING AND DIMINISH BLO 20 KT LATE TONIGHT INTO TUE AS HIGH PRES BUILDS IN BEHIND THE FRONT. ANOTHER LOW PRESSURE SYSTEM IS EXPECTED TO DEVELOP OVER THE NORTHERN PLAINS ON WED. SOUTHERLY WINDS WILL INCREASE AHEAD OF THE LOW...WITH WINDS ON EASTERN LAKE SUPERIOR INCREASING TO 20 TO 25 KT WED INTO THU. THE TROUGH ASSOCIATED WITH THIS LOW IS EXPECTED TO CROSS LAKE SUPERIOR LATE THU NIGHT AND FRI. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...DLG MARINE...VOSS AVIATION...KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DULUTH MN 934 PM CDT TUE SEP 4 2007 .UPDATE... ONE MORE UPDATE TO SPREAD CLOUDS FARTHER WEST INTO BRAINERD LAKES/WALKER AREAS. && .PREV DISCUSSION... /ISSUED 756 PM CDT TUE SEP 4 2007/ UPDATED TO ADD FOG AND DRIZZLE MAINLY NR LK SUPERIOR. PREV DISCUSSION... /ISSUED 714 PM CDT TUE SEP 4 2007/ UPDATE... UPDATED FOR CURRENT CLOUD TREND. STRATUS DECK ENTRENCHED OVER THE NORTHLAND...NORTH OF LINE FROM CENTRAL KOOCHICHING COUNTY THROUGH EASTERN AITKIN COUNTY AND ACROSS FAR NORTHERN WISCONSIN. SATL LOOP SHWS THE CLOUDS ERODING IN THE FAR NORTHWEST AND EXPANDING IN THE SOUTHWEST AND SOUTH...BUT WITH SUNSET EXPECT EROSION TO END. RUC SUPPORTS THIS TREND. WILL NEED TO KEEP AN EYE ON VSBY TRENDS AND FOG...ESPECIALLY NR LK SUPERIOR. PREV DISCUSSION... /ISSUED 210 PM CDT TUE SEP 4 2007/ DISCUSSION... WFNT STILL STRETCHED OUT W-E ACRS OUR CWA. SOME CU EVIDENT ALG THE BNDRY...BUT STRONGLY CAPPED ATMOS AND APPROACHING UPR LVL RIDGE SUPPRESSING CONVECTION FOR THE MOST PART. UPR LVL RIDGE SPENDS MOST OF WED TRANSITING THE WRN GRT LKS FOR DRY FCST...THEN SWLY FLOW REGIME RESUMES BRINGING A SERIES OF S/WVS INTO THE REGION ALONG WITH A MORE SUBSTANTIAL TROF LATE THU INTO FRI. A WELL DEFINED SFC LOW IS GENERATED...WITH AN INITIAL WFNT PASSING THRU OUR AREA LATE THU. DRY SLOT WILL MAKE FCST A BIT TRICKY AT THAT POINT...BUT CFNT QUICKLY SWEEPS THRU EARLY FRI. THERE WILL BE A BRIEF BREAK IN THE ACTION FRI NIGHT/EARLY SAT BEFORE ANOTHER STRONG UPR LVL TROF SWINGS ACRS THE NRN PLAINS TWRD THE WRN GRT LKS FOR ANOTHER ROUND OF SHRA/TSTMS ON SAT. EARLY PART OF NXT WEEK LOOKS VERY UNCERTAIN ATTM DUE TO LARGE MODEL DIFFS. SMALL TWEAKS TO GRIDS WERE MADE...MAINLY FOR TIMING...COVERAGE...AND POPS. NOTHING MAJOR. AVIATION... LARGE AREA OF LOW STRATUS LEFT IN WAKE OF MORNING CONVECTION...WITH LIFR/IFR ALONG NORTH SHORE AND MVFR INLAND.NARROW AREA OF CONVECTIVE GROWTH ALIGNED WITH 85H THETAE AXIS MAY GENERATE BRIEF TRW AS IT SLIDES SOUTH REMAINDER OF DAY..MAINLY DLH SOUTHWARD. SFC WARM FRONT... STILL SOUTH OF CWA... WILL LIFT NORTH TONIGHT. WITH SUNSET SHOULD SEE EXPANSION OF LOW STRATUS DECK FARTHER SOUTH. BR/FG LIKELY OVERNIGHT AS BDRY MOVES NORTH AND SFC WINDS SLACKEN/LLJ INCREASES. && POINT TEMPS/POPS... DLH 57 82 63 76 / 10 10 10 50 INL 58 84 61 72 / 10 10 40 50 BRD 63 87 64 78 / 10 10 10 60 HYR 60 88 66 82 / 10 10 10 30 ASX 58 87 64 78 / 10 10 10 30 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LSZ140- LSZ141-LSZ142-LSZ143-LSZ144-LSZ145-LSZ146-LSZ147. $$ CLC/TL mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 756 PM CDT TUE SEP 4 2007 .UPDATE... UPDATED TO ADD FOG AND DRIZZLE MAINLY NR LK SUPERIOR. && .PREV DISCUSSION... /ISSUED 714 PM CDT TUE SEP 4 2007/ UPDATE... UPDATED FOR CURRENT CLOUD TREND. STRATUS DECK ENTRENCHED OVER THE NORTHLAND...NORTH OF LINE FROM CENTRAL KOOCHICHING COUNTY THROUGH EASTERN AITKIN COUNTY AND ACROSS FAR NORTHERN WISCONSIN. SATL LOOP SHWS THE CLOUDS ERODING IN THE FAR NORTHWEST AND EXPANDING IN THE SOUTHWEST AND SOUTH...BUT WITH SUNSET EXPECT EROSION TO END. RUC SUPPORTS THIS TREND. WILL NEED TO KEEP AN EYE ON VSBY TRENDS AND FOG...ESPECIALLY NR LK SUPERIOR. PREV DISCUSSION... /ISSUED 210 PM CDT TUE SEP 4 2007/ DISCUSSION... WFNT STILL STRETCHED OUT W-E ACRS OUR CWA. SOME CU EVIDENT ALG THE BNDRY...BUT STRONGLY CAPPED ATMOS AND APPROACHING UPR LVL RIDGE SUPPRESSING CONVECTION FOR THE MOST PART. UPR LVL RIDGE SPENDS MOST OF WED TRANSITING THE WRN GRT LKS FOR DRY FCST...THEN SWLY FLOW REGIME RESUMES BRINGING A SERIES OF S/WVS INTO THE REGION ALONG WITH A MORE SUBSTANTIAL TROF LATE THU INTO FRI. A WELL DEFINED SFC LOW IS GENERATED...WITH AN INITIAL WFNT PASSING THRU OUR AREA LATE THU. DRY SLOT WILL MAKE FCST A BIT TRICKY AT THAT POINT...BUT CFNT QUICKLY SWEEPS THRU EARLY FRI. THERE WILL BE A BRIEF BREAK IN THE ACTION FRI NIGHT/EARLY SAT BEFORE ANOTHER STRONG UPR LVL TROF SWINGS ACRS THE NRN PLAINS TWRD THE WRN GRT LKS FOR ANOTHER ROUND OF SHRA/TSTMS ON SAT. EARLY PART OF NXT WEEK LOOKS VERY UNCERTAIN ATTM DUE TO LARGE MODEL DIFFS. SMALL TWEAKS TO GRIDS WERE MADE...MAINLY FOR TIMING...COVERAGE...AND POPS. NOTHING MAJOR. AVIATION... LARGE AREA OF LOW STRATUS LEFT IN WAKE OF MORNING CONVECTION...WITH LIFR/IFR ALONG NORTH SHORE AND MVFR INLAND.NARROW AREA OF CONVECTIVE GROWTH ALIGNED WITH 85H THETAE AXIS MAY GENERATE BRIEF TRW AS IT SLIDES SOUTH REMAINDER OF DAY..MAINLY DLH SOUTHWARD. SFC WARM FRONT... STILL SOUTH OF CWA... WILL LIFT NORTH TONIGHT. WITH SUNSET SHOULD SEE EXPANSION OF LOW STRATUS DECK FARTHER SOUTH. BR/FG LIKELY OVERNIGHT AS BDRY MOVES NORTH AND SFC WINDS SLACKEN/LLJ INCREASES. && POINT TEMPS/POPS... DLH 57 82 63 76 / 10 10 10 50 INL 58 84 61 72 / 10 10 40 50 BRD 63 87 64 78 / 10 10 10 60 HYR 60 88 66 82 / 10 10 10 30 ASX 58 87 64 78 / 10 10 10 30 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LSZ140- LSZ141-LSZ142-LSZ143-LSZ144-LSZ145-LSZ146-LSZ147. $$ CLC/TL mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 714 PM CDT TUE SEP 4 2007 .UPDATE... UPDATED FOR CURRENT CLOUD TREND. STRATUS DECK ENTRENCHED OVER THE NORTHLAND...NORTH OF LINE FROM CENTRAL KOOCHICHING COUNTY THROUGH EASTERN AITKIN COUNTY AND ACROSS FAR NORTHERN WISCONSIN. SATL LOOP SHWS THE CLOUDS ERODING IN THE FAR NORTHWEST AND EXPANDING IN THE SOUTHWEST AND SOUTH...BUT WITH SUNSET EXPECT EROSION TO END. RUC SUPPORTS THIS TREND. WILL NEED TO KEEP AN EYE ON VSBY TRENDS AND FOG...ESPECIALLY NR LK SUPERIOR. && .PREV DISCUSSION... /ISSUED 210 PM CDT TUE SEP 4 2007/ DISCUSSION... WFNT STILL STRETCHED OUT W-E ACRS OUR CWA. SOME CU EVIDENT ALG THE BNDRY...BUT STRONGLY CAPPED ATMOS AND APPROACHING UPR LVL RIDGE SUPPRESSING CONVECTION FOR THE MOST PART. UPR LVL RIDGE SPENDS MOST OF WED TRANSITING THE WRN GRT LKS FOR DRY FCST...THEN SWLY FLOW REGIME RESUMES BRINGING A SERIES OF S/WVS INTO THE REGION ALONG WITH A MORE SUBSTANTIAL TROF LATE THU INTO FRI. A WELL DEFINED SFC LOW IS GENERATED...WITH AN INITIAL WFNT PASSING THRU OUR AREA LATE THU. DRY SLOT WILL MAKE FCST A BIT TRICKY AT THAT POINT...BUT CFNT QUICKLY SWEEPS THRU EARLY FRI. THERE WILL BE A BRIEF BREAK IN THE ACTION FRI NIGHT/EARLY SAT BEFORE ANOTHER STRONG UPR LVL TROF SWINGS ACRS THE NRN PLAINS TWRD THE WRN GRT LKS FOR ANOTHER ROUND OF SHRA/TSTMS ON SAT. EARLY PART OF NXT WEEK LOOKS VERY UNCERTAIN ATTM DUE TO LARGE MODEL DIFFS. SMALL TWEAKS TO GRIDS WERE MADE...MAINLY FOR TIMING...COVERAGE...AND POPS. NOTHING MAJOR. AVIATION... LARGE AREA OF LOW STRATUS LEFT IN WAKE OF MORNING CONVECTION...WITH LIFR/IFR ALONG NORTH SHORE AND MVFR INLAND.NARROW AREA OF CONVECTIVE GROWTH ALIGNED WITH 85H THETAE AXIS MAY GENERATE BRIEF TRW AS IT SLIDES SOUTH REMAINDER OF DAY..MAINLY DLH SOUTHWARD. SFC WARM FRONT... STILL SOUTH OF CWA... WILL LIFT NORTH TONIGHT. WITH SUNSET SHOULD SEE EXPANSION OF LOW STRATUS DECK FARTHER SOUTH. BR/FG LIKELY OVERNIGHT AS BDRY MOVES NORTH AND SFC WINDS SLACKEN/LLJ INCREASES. && POINT TEMPS/POPS... DLH 57 82 63 76 / 10 10 10 50 INL 58 84 61 72 / 10 10 40 50 BRD 63 87 64 78 / 10 10 10 60 HYR 60 88 66 82 / 10 10 10 30 ASX 58 87 64 78 / 10 10 10 30 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LSZ140- LSZ141-LSZ142-LSZ143-LSZ144-LSZ145-LSZ146-LSZ147. $$ CLC mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 943 PM CDT MON SEP 3 2007 .UPDATE... NO MAJOR CHANGES ATTM. AS PER SPC MCD...EXPECT TSTMS TO INCREASE IN COVERAGE TNT OVR ARROWHEAD AS 35 KT LOLVL JET INTERACTS WITH SFC FRONT. RUC SHOW STRONG 850 MB FRONT-GENESIS THROUGHOUT MUCH OF THE NIGHT...AND THERE IS STILL STRONG IN THE ARROWHEAD LEADING TO MORE TSTMS...WILL LEAVE FCST AS IS. WILL NEED TO KEEP AN EYE ON KDLH AND LAKE SUPERIOR SHORE AREAS. OFF LAKE WINDS COULD PUT US IN THE FOG AND DRIZZLE MODE. WILL TAKE A CLOSER LOOK AT THAT SCENARIO. && .PREV DISCUSSION... /ISSUED 222 PM CDT MON SEP 3 2007/ SCT SHRA/TS OCCURRING ATTM N OF A FNTL BNDRY ACRS SRN MN/WI. THIS BNDRY EXPECTED TO EDGE NWD TNGT AS A WFNT. THERMALLY CAPPED ATMOS AND LACK OF ABUNDANT MSTR WILL LIMIT SVR PROBABILITIES...BUT SLY 30 KT 850 MB JET INTERSECTING THE FNT COULD PROVIDE ENUF LIFT TO PRODUCE SOME ISOLD STRONG ELEVATED STORMS...ESPECIALLY DURING THE EVE HRS. SEE SWODY1 DISC FOR MORE DETAILS. LTL CHG NEEDED TO ONGOING FCST. AFTER THAT WE ARE LOOKING AT A BRIEF DRY PD ON WED AS THE UPPER RIDGE REBUILDS...THEN LOW POPS FOR THE REST OF THE WEEK AS A SERIES OF S/WVS TRANSIT THE AREA IN FAST ZONAL FLOW ALOFT. BEST RAIN CHANCES WILL BE THU NIGHT/FRI AS A DEEPER MORE WELL DEFINED UPR TROF SWINGS ACRS THE THE UPPER GRT LKS REGION. ONLY MINOR ADJUSTMENTS WERE NEEDED TO THE EXTENDED PDS OF THE FCST. && .AVIATION... && .PREV DISCUSSION... /ISSUED 222 PM CDT MON SEP 3 2007/ AVIATION... SCT TSRA WILL INCREASE IN COVERAGE THIS EVENING AND OVERNIGHT...RESULTING IN LOWERING CIGS AND VSBYS. CONDITIONS WILL DETERIORATE QUICKLY AFT 06Z TO MVFR WITH SCT IFR AND AREAS OF LIGHT FOG. LCL IFR CIGS CAN BE EXPECTED AROUND DLH BTWN 06-14Z DUE TO A GUSTY NE WIND OFF OF LAKE SUPERIOR. && POINT TEMPS/POPS... DLH 54 67 57 82 / 50 20 10 10 INL 51 76 58 84 / 60 10 10 10 BRD 61 85 62 87 / 20 10 10 10 HYR 58 81 60 88 / 20 20 10 10 ASX 57 71 58 87 / 60 30 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 10 PM CDT TUESDAY FOR LSZ121-LSZ141- LSZ142-LSZ143-LSZ144-LSZ145-LSZ146-LSZ147-LSZ148-LSZ162. $$ CLC mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 351 AM CDT MON SEP 3 2007 .DISCUSSION... MSAS ANALYSIS FEATURES COLD FRONT WELL SOUTH OF CWA...STRETCHING FROM THE ERN GREAT LAKES THROUGH SRN MN...WEST TO AN AREA OF LOW PRESS OVER ERN MT. BUBBLE OF HIGH PRESS AT SFC IS BUILDING SOUTH FROM LAKE OF THE WOODS VICINITY. A SHORTWAVE...IN BRISK WESTERLY MID LVL FLOW...IS RACING ACROSS SRN MB WITH SOME WEAK RADAR RETURNS INDICATED ON DRYDEN RADAR.RUC ANALYSIS SUGGESTS AN AREA OF DIVERGENCE ASSOCIATED WITH U/L JET MAY BE ENHANCING LIFT. AN AREA OF MID LVL FRONTOGENESIS HAS ALSO DEVELOPED ALONG ND/MB BORDER AND IS TRANSLATING EASTWARD. MID LVL CLOUDS ARE SWEEPING FROM ND EAST INTO WRN PART OF CWA. CLEAR SKIES/LIGHT WINDS/LOW SFC T/TD DEPRESSIONS HAVE ALLOWED SOME FOG TO FORM OVER ERN EDGE OF CWA. SHORTWAVE ALONG CANADIAN BORDER WILL MOVE QUICKLY EAST TODAY WITH AN AREA OF SFC/85/70H FRTGNSIS PUSHING ACROSS MOST OF CWA. LL MOISTURE IS LACKING SO DESPITE FORCING POPS ARE HARD TO COME BY. BOTH GFS/NAM INCREASE 85H TD RAPIDLY THIS AFTERNOON OVER SWRN CORNER OF CWA HOWEVER MID LVL WARMING SIMULTANEOUSLY SHOULD INHIBIT CONVECTION. MAJORITY OF GUIDANCE SUPPORTS A SLOWER...FARTHER NORTH TREND IN PRECIP EVOLUTION COMPARED TO PREVIOUS FCST.CONSEQUENTLY WILL USE MULTI-MODEL BLEND AND PUSH MAIN AREA OF PRECIP FROM NRN CWA EAST AND SLIGHTLY FARTHER SOUTH DURING THE OVERNIGHT HOURS. BOTH 21Z...AND NOW 3Z SREF SUGGEST BEST COMBINATION OF FORCING/DEEP MSTR WILL STRETCH ACROSS MOST OF THE NRN CWA...FROM THE FALLS EAST TO THE ARROWHEAD.LOWEST POPS ACROSS SRN/SERN CWA. MOST OF THE ORGANIZED SYNOPTIC SCALE ASCENT SHOULD DIMINISH EARLY TUESDAY. HOWEVER GFS SUGGEST 85H SPEED CONVERGENCE WITH LINGERING 85/50H OMEGA MAY ALLOW SOME LINGERING PRECIP ACROSS ERN CWA.GFS COOLS 100/85H THICKNESS LAYER AS 85H TRAJECTORY REMAINS SOUTHWEST AT 10 TO 20KTS...IMPLYING DECENT SATURATION.CLOUDS SHOULD LINGER INTO WEDNESDAY OVER MOST OF ERN CWA. EXTENDED...INTERESTING PATTERN AS SFC WARM FRONT LIFTS NORTH OF CWA WEDNESDAY...OPENING THE DOOR FOR INFLUX OF SIGNIFICANT PWS. WARM AND MUGGY AIR WILL INVADE THE REGION.BOTH GFS/ECMWF SUGGEST A STRONG FRONTAL SYSTEM WILL APPROACH THE CWA THURSDAY. ALTHOUGH TOO EARLY TO PINPOINT AT THIS TIME...GFS FCST INCLUDES 85H MSTR FLUX ANOMALIES OF 3 TO 5 S.D. ABOVE AVERAGE. HOPEFULLY SOME MUCH NEEDED RAIN WILL RESULT. && .AVIATION... VFR CONDITIONS WILL PREVAIL ACROSS THE NORTHLAND TODAY...HOWEVER LCL BR WITH MVFR-IFR VSBYS WILL OCCUR ACROSS THE AREA THROUGH EARLY THIS MORNING. SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP ALONG THE CANADIAN BORDER BY AFTERNOON...THEN SLOWLY DRIFT SOUTHWARD AND AFFECT THE NORTHERN QUARTER OF MN THROUGH TONIGHT. WINDS ARE EXPECTED TO TURN OUT OF THE EAST...WHICH MAY CAUSE A MVFR/IFR DECK OF CLOUDS TO DEVELOP ACROSS AREAS INVOF LAKE SUPERIOR TONIGHT. && POINT TEMPS/POPS... DLH 71 54 74 57 / 10 50 20 10 INL 70 51 76 58 / 60 60 10 10 BRD 81 61 85 62 / 10 20 10 10 HYR 80 58 81 60 / 10 20 20 10 ASX 74 57 76 58 / 10 60 30 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ CANNON/BERDES mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 1153 AM CDT TUE SEP 4 2007 .UPDATE...DID A QUICK UPDATE TO ADJUST WORDING. RAIN HAS NOT QUITE DEVELOPED THIS MORNING LIKE EXPECTED...ALTHOUGH THERE WAS PLENTY OF MOISTURE HANGING AROUND. LEFT SLIGHT CHANCE POPS IN FOR THE MORNING PERIOD...BUT WILL LIKELY LEAVE OUT MORNING FOR NOW. A FEW SHOWERS CAN NOT BE RULED OUT ALONG THE HIGHWAY 82 CORRIDOR...BUT NOT EXPECTING ANYTHING TO MEASURE AT THIS POINT. LOWERED POPS SLIGHTLY IN THE AFTERNOON FOR THE SOUTHWEST AND KEPT EVERYTHING WEST OF I-55 LIKELY. MODELS CONTINUE TO SUGGEST DRY AIR WILL MOVE INTO THE EAST AND MAINTAINED LOWER POPS...BACKED OFF A LITTLE FOR THE SOUTHEAST. LOOKS LIKE SHOWERS WERE FORMING ALONG A BOUNDARY OR SOMETHING AND SPREADING NORTH ACROSS THE STATE. THE RUC SUGGESTS THERE IS A WEAKNESS IN THE RIDGE...WITH A POSSIBLE DISTURBANCE OVER ARK AND THE AXIS EXTENDING INTO MS. WHATEVER THE CASE...THE WESTERN ZONES STILL LOOK FOR FAVORABLE FOR RAIN THROUGH THE DAY...SO MAINTAINED THE HIGHER POPS...FOR NOW MUCH OF THE ACTIVITY MAY GO AROUND THE RIDGE...WILL CONTINUE TO MONITOR AND UPDATE AS NEEDED. TEMPS SEEMED OK...DID NOT LOWER AT THIS POINT. ALTHOUGH THERE WERE CLOUDS ALL OVER THE CWA...THERE WERE SOME BREAKS. TEMPS WERE IN THE LOWER AND MID 80S FOR MOST OF THE AREA...SO TEMPS NEAR 90 SEEM REASONABLE. OVERALL NO REAL CHANGES TO THE SHORT TERM FORECAST. TWEAKED...THE POPS AND DEWPOINTS TO ACCOUNT FOR THE DELAY IN THE DRY AIR. OTHERWISE THE FORECAST WAS OK. && .AVIATION... VFR/MVFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. A FEW SHOWERS WILL MOVE THROUGH THE AREA EARLY IN THE AFTERNOON...BUT NOT EXPECTING ANY REAL OBSTRUCTIONS TO VISIBILITIES BEFORE 21Z. SCATTERED THUNDERSTORMS IN THE AFTERNOON MAY REDUCE VISIBILITIES TO 3 MILES...OCCASIONALLY LESS...ESPECIALLY FOR GLH/GWO. HOWEVER THE REST OF THE SITES MAY SEE A FEW STORMS ALSO WITH SIMILAR CONDITIONS. WILL MAINTAIN VICINITY WORDING THROUGH 21Z AND CONTINUE THE TEMPO GROUPS FOR THE TYPICAL AFTERNOON AND EARLY EVENING ACTIVITY. NOT SURE HOW MUCH FOG WILL DEVELOP OVERNIGHT...SOUTHERLY WINDS WILL CONTINUE TO BRING IN MOISTURE. GUIDANCE SHOWS CLOUDS OVERNIGHT...BUT NO REAL CEILINGS. WITH CIRRUS BLOWING INTO THE AREA FROM THE WEST...HIGH CLOUDS WILL LIKELY MAINTAIN...BUT WILL NOT RULE OUT STRATUS MOVING IN LATE. && .PRELIMINARY POINT TEMPS/POPS... JACKSON 89 69 90 70 / 43 26 41 24 MERIDIAN 92 65 91 69 / 19 14 17 12 VICKSBURG 89 70 89 70 / 58 38 55 36 HATTIESBURG 91 69 93 70 / 35 17 23 19 NATCHEZ 88 70 89 70 / 60 32 59 37 GREENVILLE 89 70 87 70 / 61 44 69 47 GREENWOOD 90 69 87 69 / 56 27 53 36 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ 7 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 110 AM CDT MON SEP 3 2007 .DISCUSSION...ISOLATED SHRA DIMINISHING THIS EVENING OVER MAINLY SRN MS. BOTH RUC/LOCAL WRF DO NOT DEVELOP MUCH IF ANY ADDITIONAL ACTIVITY THROUGH THE OVERNIGHT HOURS SO WILL REMOVE POPS COMPLETELY AFTER 11 PM OR SO. NEAR OR ABOVE 2 INCH PWATS REMAIN IN PLACE AND ALREADY LESS THAN 5F TEMP/DEWPT SPREADS MUCH OF THE AREA S OF I-20. THINNING HIGH LEVEL MOISTURE COULD EASILY LEAD TO AREAS OF LOW STRATUS/PATCHY FOG FOR CENTRAL AND SRN LOCATIONS. DIFFUSE STATIONARY BOUNDARY ALONG I-10 SEEMS TO BE SLOWLY LIFTING NWD TO AROUND I-20 BY MONDAY AFTERNOON AND HIGHWAY 82 TUESDAY AFTERNOON. IN ANY CASE...ABOVE NORMAL POPS SHOULD PROBABLY CONTINUE UNTIL MID WEEK. WEB GRPAHICS/GRIDS SHOULD BE POSTED AND ZONE PACKAGE SENT./40/ PREVIOUS DISCUSSION FOLLOWS...WARM MOIST CONVEYOR BELT WAS BETWEEN A MID-UPPER LOW OVER CENTRAL TEXAS AND THE MID-UPPER HIGH CENTERED OVER THE NORTHEAST GULF. THIS SHOULD HELP MAINTAIN OUR WARM MOIST AIRMASS(PWATS >=2IN) THROUGH THE SHORT TERM. HAVE GONE A FEW DEGREES WARMER THAN MAV GUIDANCE LOWS FOR TONIGHT. THE PREVIOUS 00Z MAV TEMPS WERE AMONG THE LOWEST ENSEMBLE MEMBERS AND THE 12Z MAV MOS CAME IN TOO LOW AS WELL. THE WEATHER LABOR DAY WILL BE SIMILAR TO TODAY`S WITH THE WARMEST TEMPERATURES OVER THE DELTA. THE DEEPEST MOISTURE AND GREATEST CHANCE FOR RAIN WILL BE CARRIED IN THE SOUTHERN HALF AGAIN. BOTH THE NAM AND GFS SHOW DRIER AIR TRYING TO MOVE INTO OUR NORTHEAST COUNTIES BY AFTERNOON AS SURFACE HIGH PRESSURE WEDGES DOWN EAST OF THE APPALACHIANS AND SPREADS DRIER AIR WESTWARD. THIS MAY LIMIT CONVECTION IN THE NORTHEAST. DRIER AIR HAS LIMITED COVERAGE OVER THE DELTA THE PAST COUPLE OF DAYS BUT AREAL COVERAGE SHOULD INCREASE OVER THE DELTA REGION WITH THE MOISTURE SURGE ASSOCIATED WITH THE LOW OVER TEXAS. WENT A FEW DEGREES WARMER THAN MAV AGAIN MONDAY NIGHT. CLOUD DEBRIS AND CONTINUED DECENT LOW LEVEL MOISTURE SHOULD HOLD MIN TEMPS NEAR 70 AGAIN. /22/ .LONG TERM...TUESDAY THROUGH SUNDAY. THERE MAY BE A FEW DRY DAYS BY MID WEEK...ESPECIALLY EAST...OTHERWISE MORE PARTLY CLOUDY AND WET DAYS ARE LIKELY THROUGH THE WEEK. BY TUESDAY THE MODELS STILL SHOW THE UPPER RIDGE OVER THE LOUISIANA COAST. THE UPPER TROUGH AXIS EXTENDING FROM THE GEORGIA COAST AND OLD OUTFLOW WILL REMAIN THE FOCUS FOR THUNDERSTORM DEVELOPMENT ACROSS THE CENTRAL AND SOUTHERN PORTIONS OF THE CWA THROUGH MAYBE WEDNESDAY. BY THURSDAY THE UPPER TROUGH HAS DROPPED INTO NORTH TEXAS AND THE RIDGE HAS SHIFTED INTO THE SOUTHEAST US. THE GFS CONTINUES TO SHOW DRY AIR FLOWING INTO THE EASTERN ZONES...WITH SOUTHWESTERLY FLOW ALOFT BRINGING MOISTURE INTO AREAS ALONG AND WEST OF THE MISSISSIPPI RIVER. NOT REALLY SURE WHAT HAPPENS NEXT...BUT THE GFS HAS THE UPPER LOW OFF THE GEORGIA COAST DISPLACING THE RIDGE AND COMING BACK ONSHORE...MEANWHILE THE SHORTWAVE LIFTS OUT INTO THE MIDWEST AROUND FRIDAY. MOISTURE CONTINUES TO FLOW INTO THE AREA...WITH EVERYTHING MOVING OFF TO THE NORTH. RIGHT NOW IT LOOKS LIKE SCATTERED SHOWERS AND THUNDERSTORM WILL CONTINUE TUESDAY AND WEDNESDAY WITH A POSSIBLE BREAK THURSDAY AND FRIDAY. THE TROUGH AXIS AND A COLD FRONT DRAPED ACROSS THE MUCH OF THE CENTRAL US WILL SHIFT EAST THROUGH THE WEEKEND. SCATTERED SHOWERS AND THUNDERSTORMS SPREAD ACROSS THE AREA ON SATURDAY AND SEEM TO CONTINUE THROUGH EARLY NEXT WEEK. WILL LEAVE THE HWO CLEAR THROUGH THE PERIOD AGAIN TODAY. ALTHOUGH MOISTURE RETURNS...INSTABILITY STILL LOOKS MARGINAL. 850 WINDS WERE AROUND 20 TO 25 KTS...MAYBE A FEW STRONG THUNDERSTORMS AT BEST. WOULD LIKE TO SEE HOW THE SYSTEM DEVELOPS FOR THE WEEKEND. WITH A FEW DISTURBANCES AND COLD FRONTS ALREADY MOVING THROUGH...MAY GET AN EARLY START TO FALL. TEMPERATURES WERE GOOD...CLOUDS MAY HINDER WARMING THROUGH THE WEEK...BUT ITS HARD TO SAY AT THIS POINT. WILL MAINTAIN LOWER TO MID 90S...EXPECTING SOME BREAKS IN THE CLOUDS. OVERALL NO BIG CHANGES TO THE FORECAST...EVEN WITH A FEW SUBTLE CHANGES IN THE MODEL...THE CURRENT FORECAST WAS OK. 7 && .AVIATION...MVFR FOG/HAZE DEVELOPING AT MOST SITES BY 09Z. OCCASIONAL IFR VISIBILITIES AND CEILINGS WILL BE POSSIBLE IN THE SOUTH HALF 09-13Z. VFR CONDITIONS ARE EXPECTED TO RESUME AFTER 14Z BUT HAZE HANGING ON AT SOME SITES UNTIL 17Z. AFTERNOON CONVECTION GETS GOING AGAIN ACROSS CENTRAL AND SRN COUNTIES BY 17-19Z./40/ && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 830 PM CDT MON SEP 3 2007 FORECAST CHALLENGE FOR UPDATE CONCERNS RESIDUAL PCPN CHANCES AND TEMPERATURES. SURFACE LOW PRESSURE CENTERED OVER KFAR WITH WARM FRONT EXTENDING SE INTO WESTERN WI. BOUNDARIES PRIMARY INFLUENCE HAS BEEN TEMPERATURES AS STRONG CAPPING INHIBITING ANY SURFACE BASED CONVECTION. CONVECTION ALONG NORTHERN TIER TODAY AND EVENING LINING UP WELL WITH ZONE OF 850MB CONVERGENCE AND STRONG WARM ADVECTION. RUC SHIFTS FEATURES NE AND LOOKS GOOD AS CONVECTION FROM KMVX-88D AND LIGHTNING STRIKES SHIFTING EAST OF FORECAST AREA. AS A RESULT WILL TRIM BACK ON POPS AND COVERAGE REMAINDER OF NIGHT. BIG SURFACE THERMAL GRADIENT EXISTS WITH MID 60S OVER FAR NE AND MID 80S ACROSS THE SOUTH. AS SURFACE LOW SHIFTS EAST WEAK NORTHERLY FLOW BRINGS IN COOLER AIR HOWEVER WITH DEWPOINTS HOLDING UP LOOKS TO BE MILD NIGHT ACROSS SOUTH AND MORE AVERAGE MINIMUMS ELSEWHERE. OVERALL CURRENT FORECAST TEMPERATURES LOOK GOOD. && .AVIATION... VFR WITH ISOLATED TSRA CONFINED TO FAR NE FORECAST AREA. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ VOELKER nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 855 PM CDT TUE SEP 4 2007 .UPDATE... UPDATED FORECAST WAS SHIPPED OUT EARLIER TO DEAL WITH VERY MINOR CONVECTIVE ACTIVITY ALONG THE MISSOURI RIVER NEAR PIERRE. WSR-88D SHOWS THIS ACTIVITY HAS DISSIPATED. REST OF THE FORECAST LOOKS GOOD. && .PREV DISCUSSION... .SHORT TERM...TONIGHT THROUGH 12Z FRIDAY. MAIN FORECAST CHALLENGE IN THE NEAR TERM DEALS WITH TIMING OF COLD FRONTAL PASSAGE THURSDAY...AND TEMPS UP TO THAT POINT. MSAS ANLYS CONTS TO SHOW WARM FRONT DRAPED ACROSS SD/ND BORDER WITH SFC LOW IN THE VCNTY OF PHP. LATEST RUC SHOWS PRESSURE FALLS OCCURRING ACROSS CENTRAL SD INDICATING THAT THE LOW MIGHT BE SLOWLY MOVING EAST...LIFTING THE WARMFRONT TO THE NORTH. HAVE BOLSTERED LOWS A BIT MORE OVERNIGHT GIVEN WHAT SFC DWPTS CURRENTLY ARE. HAVE ALSO GONE WITH A NEARLY CLOUDLESS SKY AS 7H TEMPS KEEP ANYTHING FROM FORMING. LOOKING AT THE COLD FROPA...MODELS ARE CONTINUING TO PUSH THIS FEATURE BACK..TO WHERE IT DOESN`T EXIT THE CWA UNTIL NEARLY EARLY FRIDAY MORNING. GIVEN SOUTHERLY FETCH OF MOISTURE DURING THE TIME...BOLSTERED DWPTS THROUGH THE PERIOD...ESPECIALLY ACROSS THE EAST. 7H CAPPING TEMPS REMAIN WELL IN PLACE ALSO KEEPING ANY CONVECTION AT BAY UNTIL FRONT PUSHES THROUGH THURSDAY. NOW THAT FRONT IS PROGGED TO COME THROUGH DURING GOOD HEATING TIME THURSDAY...AND THAT GFS IS LIFTING DECENT 5H WAVE INTO CWA DURING THE AFTERNOON...HAVE UPPED THURSDAY EVENING POPS INTO LIKELY CATEGORY FOR THURSDAY EVENING/NIGHT TIME PERIODS. STRONG FORCING ON THE 310K AND 315K LAYERS DURING THE AFTERNOON/EVENING HOURS ON THURSDAY SUPPORT THIS...AND WITH PWATS AROUND 1.80 INCHES /NAM/ TO OVER 2 INCHES /GFS/ BY 00Z FRIDAY...POSSIBLE THAT LOCALLY HEAVY RAIN IS POSSIBLE. ALSO NOTICED THAT SPC HAS HIGHLIGHTED THURSDAY /DAY3/ FOR A SLIGHT RISK OF SEVERE. THE NAM STILL LOOKS TO BE A BIT QUICKER THAN THE GFS...SO HAVE SIDED WITH THE SLOWER GFS. GIVEN THIS...HAVE HELD ONTO CLOUDS A BIT LONGER AS WELL ACROSS THE CWA THURSDAY AND THURSDAY NIGHT. .LONG TERM...FRIDAY THROUGH TUESDAY NIGHT SIGNS OF THE APPROACHING AUTUMN CONTINUE TO APPEAR IN THE LONG RANGE PERIOD THIS AFTERNOON...WITH COOLER TEMPERATURES APPARENT AND MODEL UNCERTAINTY ABUNDANT TOWARD THE END OF THE PERIOD AS THE NUMERICAL MODELS HAVE TROUBLE RESOLVING THE CHANGING METEOROLOGICAL PATTERNS. IN GENERAL...INDICATIONS FROM THE PREVIOUS DAY OF GFS/ECMWF/GEM/GFS ENSEMBLE/DGEX MODEL RUNS ARE THAT THE INITIAL IMPULSE MOVING THROUGH THE PLAINS ON THURSDAY/THURSDAY NIGHT MAY BE FOLLOWED BY SEVERAL MORE WAVES THROUGHOUT THE LONG TERM PERIOD...LIKELY REINFORCING A BROAD UPPER LEVEL TROUGH ACROSS THE NORTHERN CONUS THROUGH THE LONG RANGE PERIOD. THERE ARE DIFFERENCES IN DETAILS HOWEVER...INCLUDING LOCATION OF THE DEEPEST PART OF THE TROUGH. THERE IS GENERAL AGREEMENT THAT ENERGY MOVING ONSHORE NEAR THE QUEEN CHARLOTTE ISLANDS IN BRITISH COLUMBIA THURSDAY WILL DIVE SOUTHEASTWARD THROUGH THE NORTHERN PLAINS BY LATE FRIDAY INTO SATURDAY...BUT EXACT LOCATION...AMPLITUDE AND TIMING DIFFERENCES EXIST...WITH THE 12Z DGEX FURTHER SOUTH AND QUICKER WITH THE SHORTWAVE THAN THE GFS...AND THE 00Z ECMWF WEAKER WITH THIS ENERGY ACROSS THE REGION. THE 12Z GFS IS THE DEEPEST OF THE THREE...WHILE SMOOTHED GFS AND GEM ENSEMBLE MEANS REFLECT THE RANGE IN ENSEMBLE SOLUTIONS REGARDING THE STRENGTH OF THE SYSTEM. CONTINUATION OF SLIGHT POPS FRIDAY NIGHT THROUGH SATURDAY EVENING WAS THE MOST LOGICAL WAY TO HANDLE THIS UNCERTAINTY FOR THE TIME BEING...WITH MOST MODEL SOLUTIONS ALSO CARRYING THE BULK OF PRECIPITATION TO THE NORTH OF THE CWA...BUT THIS ALSO DEPENDS ON THE LOCATION OF THE WAVE. EVOLUTION OF THE UPPER PATTERN BEYOND THIS SYSTEM IS RATHER UNCERTAIN WITH MODEL SOLUTIONS DISAGREEING QUITE A BIT ON THEIR HANDLING OF THE PATTERN. THE 12Z GFS RUN BROKE CONTINUITY BY CUTTING OFF A LOW IN THE PACIFIC NORTHWEST ON MONDAY AND TUESDAY FROM ENERGY DIVING DUE SOUTH FROM THE YUKON AND NORTHWEST TERRITORIES THROUGH THE WEEKEND WHICH FORCES A RESULTING RIDGE TO BUILD OVER THE PLAINS...WHILE THE 00Z ECMWF/12Z DGEX/12Z GEM AGREE WITH PREVIOUS GFS RUNS IN CONTINUING A TROUGH THROUGH THE EASTERN PLAINS AND GREAT LAKES REGIONS...WITH INCREASING LOCATION AND MAGNITUDE DIFFERENCES. THOUGH THIS DOES NOT SEEM TO BE A LIKELY SCENARIO...GIVEN THAT SEVERAL 12Z GFS AND GEM ENSEMBLE SOLUTIONS ALSO AGREE WITH THE GFS...CAN NOT RULE THIS COMPLETELY OUT... BUT WILL CONTINUE TO HINGE UPON THE PREVIOUS GFS AND THE REMAINDER OF THE MODEL SUITE FOR GENERAL FEATURES. THUS...CARRIED POPS SUNDAY NIGHT AND MONDAY FOR INDICATIONS OF ANOTHER WAVE MOVING THROUGH THE NORTHERN PLAINS THAT DEVELOPS FROM PACIFIC ENERGY MOVING INTO THE BRITISH COLUMBIA COAST ON SATURDAY. KEPT TEMPERATURES NEAR THE SAME LEVELS AS INHERITED...THOUGH THE OVERALL PATTERN DEVELOPMENT WILL OBVIOUSLY DICTATE TEMPERATURES THROUGH THE END OF THE PERIOD WITH THE POTENTIAL WAVES REINFORCING THE BROAD TROUGH OVER THE AREA OR JUST TO THE EAST. && .AVIATION... VFR CONDITIONS ARE HOLDING ACROSS THE REGION. CEILINGS ARE UNLIMITED AND VISIBILITY IS UNRESTRICTED. SOME MINOR CONVECTIVE CLOUDS BRIEFLY POPPED UP NEAR KPIR BUT HAVE SINCE DISSIPATED. EXPECT VFR CONDITIONS TO PREVAIL THROUGH THIS TIME TOMORROW. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...KEEFE SHORT TERM...HINTZ LONG TERM...ECKSTEIN AVIATION...KEEFE sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 332 PM CDT TUE SEP 4 2007 .SHORT TERM...TONIGHT THROUGH 12Z FRIDAY. MAIN FORECAST CHALLENGE IN THE NEAR TERM DEALS WITH TIMING OF COLD FRONTAL PASSAGE THURSDAY...AND TEMPS UP TO THAT POINT. MSAS ANLYS CONTS TO SHOW WARM FRONT DRAPED ACROSS SD/ND BORDER WITH SFC LOW IN THE VCNTY OF PHP. LATEST RUC SHOWS PRESSURE FALLS OCCURRING ACROSS CENTRAL SD INDICATING THAT THE LOW MIGHT BE SLOWLY MOVING EAST...LIFTING THE WARMFRONT TO THE NORTH. HAVE BOLSTERED LOWS A BIT MORE OVERNIGHT GIVEN WHAT SFC DWPTS CURRENTLY ARE. HAVE ALSO GONE WITH A NEARLY CLOUDLESS SKY AS 7H TEMPS KEEP ANYTHING FROM FORMING. LOOKING AT THE COLD FROPA...MODELS ARE CONTINUING TO PUSH THIS FEATURE BACK..TO WHERE IT DOESN`T EXIT THE CWA UNTIL NEARLY EARLY FRIDAY MORNING. GIVEN SOUTHERLY FETCH OF MOISTURE DURING THE TIME...BOLSTERED DWPTS THROUGH THE PERIOD...ESPECIALLY ACROSS THE EAST. 7H CAPPING TEMPS REMAIN WELL IN PLACE ALSO KEEPING ANY CONVECTION AT BAY UNTIL FRONT PUSHES THROUGH THURSDAY. NOW THAT FRONT IS PROGGED TO COME THROUGH DURING GOOD HEATING TIME THURSDAY...AND THAT GFS IS LIFTING DECENT 5H WAVE INTO CWA DURING THE AFTERNOON...HAVE UPPED THURSDAY EVENING POPS INTO LIKELY CATEGORY FOR THURSDAY EVENING/NIGHT TIME PERIODS. STRONG FORCING ON THE 310K AND 315K LAYERS DURING THE AFTERNOON/EVENING HOURS ON THURSDAY SUPPORT THIS...AND WITH PWATS AROUND 1.80 INCHES /NAM/ TO OVER 2 INCHES /GFS/ BY 00Z FRIDAY...POSSIBLE THAT LOCALLY HEAVY RAIN IS POSSIBLE. ALSO NOTICED THAT SPC HAS HIGHLIGHTED THURSDAY /DAY3/ FOR A SLIGHT RISK OF SEVERE. THE NAM STILL LOOKS TO BE A BIT QUICKER THAN THE GFS...SO HAVE SIDED WITH THE SLOWER GFS. GIVEN THIS...HAVE HELD ONTO CLOUDS A BIT LONGER AS WELL ACROSS THE CWA THURSDAY AND THURSDAY NIGHT. .LONG TERM...FRIDAY THROUGH TUESDAY NIGHT SIGNS OF THE APPROACHING AUTUMN CONTINUE TO APPEAR IN THE LONG RANGE PERIOD THIS AFTERNOON...WITH COOLER TEMPERATURES APPARENT AND MODEL UNCERTAINTY ABUNDANT TOWARD THE END OF THE PERIOD AS THE NUMERICAL MODELS HAVE TROUBLE RESOLVING THE CHANGING METEOROLOGICAL PATTERNS. IN GENERAL...INDICATIONS FROM THE PREVIOUS DAY OF GFS/ECMWF/GEM/GFS ENSEMBLE/DGEX MODEL RUNS ARE THAT THE INITIAL IMPULSE MOVING THROUGH THE PLAINS ON THURSDAY/THURSDAY NIGHT MAY BE FOLLOWED BY SEVERAL MORE WAVES THROUGHOUT THE LONG TERM PERIOD...LIKELY REINFORCING A BROAD UPPER LEVEL TROUGH ACROSS THE NORTHERN CONUS THROUGH THE LONG RANGE PERIOD. THERE ARE DIFFERENCES IN DETAILS HOWEVER...INCLUDING LOCATION OF THE DEEPEST PART OF THE TROUGH. THERE IS GENERAL AGREEMENT THAT ENERGY MOVING ONSHORE NEAR THE QUEEN CHARLOTTE ISLANDS IN BRITISH COLUMBIA THURSDAY WILL DIVE SOUTHEASTWARD THROUGH THE NORTHERN PLAINS BY LATE FRIDAY INTO SATURDAY...BUT EXACT LOCATION...AMPLITUDE AND TIMING DIFFERENCES EXIST...WITH THE 12Z DGEX FURTHER SOUTH AND QUICKER WITH THE SHORTWAVE THAN THE GFS...AND THE 00Z ECMWF WEAKER WITH THIS ENERGY ACROSS THE REGION. THE 12Z GFS IS THE DEEPEST OF THE THREE...WHILE SMOOTHED GFS AND GEM ENSEMBLE MEANS REFLECT THE RANGE IN ENSEMBLE SOLUTIONS REGARDING THE STRENGTH OF THE SYSTEM. CONTINUATION OF SLIGHT POPS FRIDAY NIGHT THROUGH SATURDAY EVENING WAS THE MOST LOGICAL WAY TO HANDLE THIS UNCERTAINTY FOR THE TIME BEING...WITH MOST MODEL SOLUTIONS ALSO CARRYING THE BULK OF PRECIPITATION TO THE NORTH OF THE CWA...BUT THIS ALSO DEPENDS ON THE LOCATION OF THE WAVE. EVOLUTION OF THE UPPER PATTERN BEYOND THIS SYSTEM IS RATHER UNCERTAIN WITH MODEL SOLUTIONS DISAGREEING QUITE A BIT ON THEIR HANDLING OF THE PATTERN. THE 12Z GFS RUN BROKE CONTINUITY BY CUTTING OFF A LOW IN THE PACIFIC NORTHWEST ON MONDAY AND TUESDAY FROM ENERGY DIVING DUE SOUTH FROM THE YUKON AND NORTHWEST TERRITORIES THROUGH THE WEEKEND WHICH FORCES A RESULTING RIDGE TO BUILD OVER THE PLAINS...WHILE THE 00Z ECMWF/12Z DGEX/12Z GEM AGREE WITH PREVIOUS GFS RUNS IN CONTINUING A TROUGH THROUGH THE EASTERN PLAINS AND GREAT LAKES REGIONS...WITH INCREASING LOCATION AND MAGNITUDE DIFFERENCES. THOUGH THIS DOES NOT SEEM TO BE A LIKELY SCENARIO...GIVEN THAT SEVERAL 12Z GFS AND GEM ENSEMBLE SOLUTIONS ALSO AGREE WITH THE GFS...CAN NOT RULE THIS COMPLETELY OUT... BUT WILL CONTINUE TO HINGE UPON THE PREVIOUS GFS AND THE REMAINDER OF THE MODEL SUITE FOR GENERAL FEATURES. THUS...CARRIED POPS SUNDAY NIGHT AND MONDAY FOR INDICATIONS OF ANOTHER WAVE MOVING THROUGH THE NORTHERN PLAINS THAT DEVELOPS FROM PACIFIC ENERGY MOVING INTO THE BRITISH COLUMBIA COAST ON SATURDAY. KEPT TEMPERATURES NEAR THE SAME LEVELS AS INHERITED...THOUGH THE OVERALL PATTERN DEVELOPMENT WILL OBVIOUSLY DICTATE TEMPERATURES THROUGH THE END OF THE PERIOD WITH THE POTENTIAL WAVES REINFORCING THE BROAD TROUGH OVER THE AREA OR JUST TO THE EAST. && .AVIATION... VFR CONDS EXPECTED ACROSS ALL TAF SITES/TWB ROUTES THROUGH 18Z WEDNESDAY. FEW ISOLD -TSRA ARE POSSIBLE FROM KFAR TO 50S OF KFAR THROUGH 01Z THIS EVENING. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...HINTZ LONG TERM...ECKSTEIN AVIATION...HINTZ sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 127 PM CDT TUE SEP 4 2007 .DISCUSSION...UPPER LEVEL LOW OVER FAR W TX CONTINUES TO ADVECT MOISTURE FROM HURRICANE HENRIETTE ACROSS MEXICO INTO SRN TX. MINOR SHORTWAVE MOVED ACROSS CWA THIS MORNING PRODUCED ISOLD TO SCT PRECIP AND NVA IN ITS WAKE HAS LEFT CWA FAIRLY DRY LATE THIS AM. WILL MAINTAIN SCHC POPS MAINLY OVER NRN ZONES AS ENHANCED CU EVIDENT ON VIS IMAGERY. UPPER LEVEL RIDGE OVER THE N CTL GULF WILL BUILD WEST OVER THE NEXT COUPLE OF DAYS INHIBITING POPS ACROSS THE REGION. END OF RAIN CHANCES LEADS TO WARMER TEMPS FOR THE LATTER HALF OF THE WEEK WITH MAX TEMPS IN THE MID TO UPPER 90S. RAIN CHANCES INCREASE EARLY NEXT WEEK AS RIDGE SHIFTS WEST AND TROPICAL MOISTURE INCREASES ACROSS THE REGION. && .MARINE...BUOY020 REPORTS A SE WIND AROUND 15 KTS WITH SWELLS NEAR 3 FT WHILE MTRPIL CHECKS IN WITH A SOUTHEAST WIND AROUND 15 KTS. A LIGHT TO MODERATE ONSHORE FLOW WILL PERSIST ALONG THE LOWER TX COASTLINE INTO THIS COMING WEEKEND IN RESPONSE TO A LITTLE BIT TIGHTER PGF RESULTING FROM PERSISTENT SURFACE TROFFING PUSHING INTO THE SOUTH CENTRAL PLAINS. THE GWW GUIDANCE LOOKS REASONABLE IN KEEPING WAVES AT OR BELOW THE 1 METER LEVEL THROUGHOUT 120 HOURS. WILL MAINTAIN THIS OVERALL TREND IN THE CURRENT CWF WORDING WITH NO SCA CONDITIONS EXPECTED AT THIS TIME. && .AVIATION...RUC MEAN RH GUIDANCE INDICATES THAT THE ATMS HAS BEGUN TO FINALLY DRY OUT SOMEWHAT AS MID LEVEL RIDGING BEGINS TO EDGE INTO THE TX COASTLINE. ACCORDINGLY...THE KBRO RADAR REFLECTIVITY SHOWS NO CONV ACTIVITY OVER THE REGION. SO EXPECT GENERAL VFR CONDITIONS TO CONTINUE FOR THE LOWER RGV AIRPORTS THROUGHOUT THE UPCOMING TAF PERIOD. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 79 92 79 92 / 10 10 10 10 BROWNSVILLE 78 93 79 93 / 10 10 10 10 HARLINGEN 77 94 77 96 / 10 10 10 10 MCALLEN 77 94 78 95 / 10 10 10 10 RIO GRANDE CITY 77 94 78 96 / 10 10 10 10 SOUTH PADRE ISLAND 80 90 80 90 / 10 10 10 10 && .BRO WATCHES/WARNINGS/ADVISORIES...NONE. && $$ THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT: HTTP://WWW.WEATHER.GOV/BROWNSVILLE 55/60/MARTINEZ tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPOKANE WA 1057 PM PDT MON SEP 3 2007 .SYNOPSIS... A WEAK PACIFIC COLD FRONT SYSTEM WILL MOVE THROUGH THE INLAND NORTHWEST TUESDAY BRINGING SCATTERED SHOWERS AND A FEW THUNDERSTORMS...LOCALLY BREEZY CONDITIONS AND COOLER TEMPERATURES. A DRY WEATHER PATTERN AND SEASONABLY MODERATE TEMPERATURE REGIME WILL PREVAIL THROUGH THE REMAINDER OF THE WORK WEEK. && .DISCUSSION... REST OF TONIGHT...THIS FORECAST HAS BECOME EXCEEDINGLY MORE DIFFICULT THAN EXPECTED DUE TO UNEXPECTED BATCH OF THUNDERSTORMS CURRENTLY BUFFETING THE PUGET SOUND AREA. THIS CLUSTER OF STORMS SEEMS TO BE FIRING IN AN IMPRESSIVE AREA OF UPPER LEVEL DIFLUENCE AHEAD OF THE OFFSHORE UPPER LEVEL LOW. WHILE THE DIFLUENCE WAS NOT UNEXPECTED...THE DEPTH AND AMOUNT OF CONVECTION IS CERTAINLY A SURPRISE. THE 00Z MODELS...SPECIFICALLY THE GFS AND NAM VASTLY UNDERESTIMATED THE AMOUNT OF POTENTIAL INSTABILITY AHEAD OF THE UPPER LOW. THE 00Z UIL SOUNDING SHOWED THE AIRMASS FROM 600 MBS AND HIGHER INITIALIZED TOO WARM AND TOO SATURATED OFF BOTH MODELS. THIS HELPS TO ACCOUNT FOR THE AMOUNT OF CONVECTION. FORTUNATELY...THE RUC SEEMS TO CAPTURE THE CURRENT WEATHER EVENTS AND MATCHES UP NICELY WITH THE MSAS AND GOES LIFTED INDEX VALUES WEST OF THE CASCADE. AS THE UPPER LEVEL LOW CONTINUES TO SLIDE ESE OVERNIGHT...THE RUC TAKES THIS POCKET OF POTENTIAL INSTABILITY INTO THE NORTH CASCADES AND WENATCHEE AREA OVERNIGHT RESULTING IN A SMALL CHANCE OF THUNDERSTORMS. FARTHER EAST...ALL INDICATIONS SUGGEST WE SHOULD SEE A DRY NIGHT. THE HOPEFULLY ERRONEOUS GFS AND NAM BOTH SUGGEST WE WILL SEE A POCKET OF ELEVATED INSTABILITY SLIDE UP FROM EC OREGON OVERNIGHT AND IMPACT THE EASTERN HALF OF THE CWA BY MORNING. SO FAR WE HAVE YET TO SEE THE WHITES OF ITS EYES...AND WILL RELY MORE WITH THE RUC SOLUTION...WHICH KEEPS THE BEST POTENTIAL INSTABILITY NEAR THE CASCADES. SINCE THE RUC INFO TERMINATES AT 15Z...THE FORECAST AFTER THAT TIME REMAINS IN QUESTION...BUT SUSPECT THE CONVECTIVE POTENTIAL WILL STEADILY DIVE ESE WITH THE DIGGING UPPER LEVEL LOW. THIS SUGGESTS THE BEST CHANCES OF THUNDER WILL REMAIN SOUTH OF THE CWA THROUGH THE DAY...BUT MODEL UNCERTAINTIES DUE TO THE POOR INITIALIZATION SUGGESTS THIS IS FAR FROM CERTAIN. FX && .AVIATION...VRF CONDITIONS EXPECTED AT ALL TAF SITES THROUGH 06Z WED. THE MAIN AVIATION CONCERN WILL REVOLVE AROUND CHANCES FOR THUNDERSTORMS. IT APPEARS AT THIS TIME THAT THE KEAT TAF HAS THE BEST CHANCE FOR THUNDER...WITH THE MAIN THREAT OCCURRING BETWEEN 10Z-18Z. ELSEWHERE...IT LOOKS LIKE CHANCES ARE QUITE LIMITED...WITH THE MAIN FOCUS DURING THE AFTERNOON LIKELY SHIFTING SOUTH OF KLWS. FX && .PRELIMINARY POINT TEMPS/POPS... SPOKANE 59 81 52 79 52 75 / 0 20 10 0 0 0 COEUR D`ALENE 55 81 51 80 50 74 / 0 20 20 0 0 0 PULLMAN 54 79 49 77 46 74 / 0 20 20 0 0 0 LEWISTON 65 85 57 84 55 80 / 0 20 30 0 0 0 COLVILLE 51 83 46 85 47 80 / 20 20 10 0 0 10 SANDPOINT 53 82 50 80 48 74 / 0 20 20 0 0 10 KELLOGG 55 80 50 78 47 73 / 0 20 20 0 0 0 MOSES LAKE 60 84 55 84 52 81 / 10 20 0 0 0 0 WENATCHEE 64 84 58 84 56 80 / 20 30 0 0 0 0 OMAK 57 85 55 85 52 81 / 20 20 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...NONE. WA...NONE. && $$ wa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 213 PM CDT MON SEP 3 2007 .SHORT TERM... TONIGHT...MODERATE LOW LEVEL JET FROM THE EASTERN PLAINS TO MINNESOTA TO PUSH INTO NORTHERN WISCONSIN BY THIS EVENING. ISOLATED ELEVATED CONVECTION HAS BEGUN ACROSS PORTIONS OF NORTHEAST MINNESOTA. CONVECTION EXPECTED TO PROPAGATE E/SOUTHEASTWARD ACROSS NORTHERN WI ALONG 850MB BAROCLINIC ZONE IN REGION OF MODERATE MOISTURE CONVERGENCE. GOOD MODEL AGREEMENT THAT MAJORITY OF ACTIVITY WILL REMAIN NORTH OF THE FORECAST AREA. LOCAL WRF 4KM AND 20 KM MODELS ALSO KEEP PRECIP TO THE NORTH. THE AC ACROSS CENTRAL WI PICKED UP ON RUC BUT MOISTURE IS AROUND 12-15 THSD FT...WITH CAP AT 5 THSD FT...SO NOT THAT CONCERNED ANYTHING FROM THIS THAT COULD CLIP FOND DU LAC/SHEBOYGAN AREA WOULD REACH THE GROUND DUE TO DRY AIR IN THE 5-10 THSD FT LAYER. WEAK UPPER RIDGING TO BUILD OVER THE GREAT LAKES REGION TUESDAY AND TUESDAY NIGHT AS STRONG SHORT WAVE TROUGH COMES ONSHORE ALONG THE PACIFIC NORTHWEST. DRY FORECAST TO CONTINUE AS FORCING NIL...AND AIRMASS IS STRONGLY CAPPED. LOW LEVEL SWLY FLOW TO PROVIDE ANOTHER VERY WARM DAY AS 850MB TEMPS REACH 18-19C. HI TEMPS TO PUSH WELL INTO THE 80S. GFS MOS DEW POINTS CONTINUE TO BE TOO LOW DUE TO THE RECENT WET SPELL. .LONG TERM... WILL KEEP DRY FORECAST GOING INTO WED AS UPPER TROUGH SLOW TO PROGRESS EASTWARD ACROSS THE ROCKIES. NAM SOUNDING REDUCE CAP AND LOW CAPES OF 500-100 J/KG ARE INDICATED. HOWEVER LITTLE IN THE WAY OF LIFT. GFS/NAM/ECMWF DO SHOW A WEAK SHORT WAVE TRYING TO LIFT NORTH THRU THE MID MISSISSIPPI VALLEY WEDNESDAY NIGHT. ALSO SOUTH FLOW AT 850MB WILL ALLOW GULF MOISTURE TO SURGE NORTHWARD INTO SOUTHERN WISCONSIN. Q-G FORCING WEAK WEDNESDAY NIGHT...BUT DECIDED TO TRIM NORTHWARD EXTENT OF THE SLIGHT CHANCE OF SHOWERS. PRIMARY UPPER SHORTWAVE AND ASSOCIATED COLD FRONT SHOULD MOVE ACROSS THE REGION THU-FRI. STILL SOME UNCERTAINTY REGARDING AMPLITUDE/STRENGTH/TIMING OF THIS SYSTEM...ALTHOUGH CONSENSUS SOLUTION INDICATES BEST POTENTIAL FOR PRECIP FRIDAY INTO SATURDAY. ECMWF STILL NOT AS PROGRESSIVE WITH THE SECOND SHORTWAVE ON SATURDAY SO WILL LINGER PRECIP CHANCE INTO SUNDAY. && .AVIATION...A WEAK STATIONARY OVER SRN WI WILL SLOWLY MOVE NWD ON TUE INTO CENTRAL WI. WINDS WILL REMAIN LIGHT TONIGHT WITH MOSTLY CLEAR SKIES AND A MOIST LOW LEVEL AIRMASS IN PLACE. AREAS OF MVFR FOG WILL MOST LIKELY DEVELOP DUE TO RADIATIONAL COOLING FROM 06Z TUE TO 13Z. VFR CONDITIONS WILL PREVAIL ON TUE. && .MKX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ HENTZ/GEHRING wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 445 AM EDT WED SEP 5 2007 .DISCUSSION... MAIN FCST CONCERNS ARE PCPN CHANCES THU THROUGH FRI. WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER THE SE AND CENTRAL CONUS BETWEEN TROUGHS OVER OR/ID/NV AND ERN CANADA RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. A SHORTWAVE AND PLENTIFUL DEEP MOISTURE WAS SLOWLY LIFTING NE FROM OK/AR TOWARD THE MID MS VALLEY. SHRA/TSRA EXITING ERN UPPER MI WERE SUPPORTED BY 850-700 MB FGEN AND CONTINUED WRLY FLOW ISENTROPIC LIFT ALONG THE 850 MB WARM FRONT. A WEAKER BAND OF SHRA HAD ALSO DEVELOPED INTO WRN MENOMINEE COUNTY ALIGNED WITH ANOTHER AREA OF WEAK TO MODERATE 310K-315K ISENTROPIC ASCENT...PER 06Z NAM. AT THE SFC...A FRONT EXTENDED THROUGH CNTRL MN AND NRN WI FROM LOW PRES OVER SE MT. EXTENSIVE LOW CLOUDS AND FOG PREVAILED NORTH OF THE FRONT...ACROSS UPPER MI AND LAKE SUPERIOR WHERE VSBYS HAD DROPPED TO AROUND 1/4SM IN SEVERAL LOCATIONS. TODAY...EXPECT THE REMAINING SHRA/TSRA OVER S UPPER MI AND SUPPORTING LIFT TO SLIDE EASTWARD WITH THE PCPN ENDING BY AROUND 12Z. A SHORTWAVE TROUGH AND LOW PRES MOVING FROM MANITOBA TO HUDSON BAY WILL HELP DRAW A WARM FRONT THROUGH UPPER MI AS SW 925 MB WINDS INCREASE TO 20-30 KT. UPSTREAM MAX READINGS FROM TUE OVER ERN MN AND NW WI ALONG WITH MIXING TO 850-800 MB (850 MB TEMPS AROUND 20C) SUPPORT MAX READINGS AROUND 90F OVER MUCH OF THE WEST HALF OF UPPER MI...ESPECIALLY WHERE DOWNSLOPE FLOW PREVAILS. LAKE MI MODIFIED AIR WILL KEEP THE ERN CWA A BIT COOLER. NO ADDITIONAL PCPN IS EXPECTED WITH SUBSTANTIAL CAPPING IN THE WARM SECTOR PREVAILING...DESPITE SIGNIFICANT LOW LEVEL MOISTURE...DEWPOINTS IN THE LOW TO MID 60S. TONIGHT AND THU...THE ACTIVE FRONTAL/BAROCLINIC ZONE WILL SET UP NORTH OF THE AREA...FROM NW MN INTO WRN ONTARIO AND MAY GRADUALLY SAG INTO NRN LAKE SUPERIOR...PER 00Z GFS. HOWEVER...EXPECT THE BULK OF THE OCNLY HEAVY SHRA/TSRA SUPPORTED BY STRONG 850-600 MB FGEN TO REMAIN N OF UPPER MI...PER MDLS CONSENSUS. HOWEVER...THE SHRTWV AND MOISTURE PLUME FROM THE MS VALLEY MAY EVENTUALLY SPREAD INTO UPPER MI WITH THE POTENTIAL FOR SCT/ISOLD IN THE AFTERNOON. THE GFS/CMC/UKMET WOULD PLACE THE GREATER PCPN CHANCES WITH THIS SYSTEM OVER THE S AND E PORTIONS OF THE CWA. THU NIGHT INTO FRI...AS THE MID LEVEL TROF MOVES FROM THE NRN PLAINS INTO THE UPPER MS VALLEY THE SFC LOW WILL LIFT NE FROM SD THROUGH NRN MN INTO NRN ONTARIO DRAGGING A COLD FRONT ACROSS UPPER MI ON FRI. THE INCREASING MOISTURE IN THE WARM SECTOR ALONG WITH THE POTENTIAL FOR WEAK SHRTWVS IN SW FLOW STILL COULD SET OFF SOME SHRA/TSRA THU NIGHT. HOWEVER...THE BEST CHANCE FOR SHRA/TSRA IS EXPECTED WITH THE FROPA AND MID LEVEL TROF PASSAGE ON FRI. DECENT LOW LEVEL CONV ALONG THE FRONT ALONG WITH MODERATE UPPER LEVEL DIV AND QVECTOR CONV JUSTIFY LIKELY POPS. CAPE VALUES NEAR 1K J/KG AND 40-50 KT 0-6KM SHEAR COULD SUPPORT SOME STRONGER TO MARGINALLY SEVERE STORMS...ESPECIALLY IF CONVECTION IS DELAYED INTO THE AFTERNOON. FRI NIGHT AND SAT...ANY LEFTOVER SHRA/TSRA WILL END QUICKLY FRI EVENING WITH STRONG DRYING MOVING IN ON BRISK NW WINDS BEHIND THE COLD FRONT. EVEN THOUGH THERE MAY BE ADDITIONAL WEAK SHORTWAVES IN WITH THE DEVELOPING BROAD TROUGHING OVER THE NRN CONUS...WITH LIMITED MOISTURE AND WEAK DYNAMIC SUPPORT...ONLY SLIGHT CHANCE POPS WERE MENTIONED OVER THE SW PORTION OF THE CWA. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT DENSE FOG/IFR VSBYS/CIGS TO LINGER AS UPR LVL DRYING/CAPPING IN WAKE OF H85 WARM FROPA MOVES OVER LINGERING LLVL MSTR/SHALLOW FNTL INVRN. CONDITIONS SHOULD IMPROVE DRAMATICALLY TO VFR WED MRNG ONCE SFC WARM FNT SHIFTS TO THE N. DIURNAL MIXING WL ALLOW DVLPMNT OF GUSTY SW WINDS...ESPECIALLY AT SAW. LOOK FOR LLWS ONCE SUN SETS AND LLJ UNDERGOES NOCTURNAL INTENSIFICATION ABV RADIATION INVRN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... A COLD FRONT OVER THE DAKOTAS WILL MOVE INTO THE MN ARROWHEAD LATE TONIGHT. AHEAD OF THE FRONT...WINDS MAY GUST UP TO 30 KT TONIGHT ON BOTH HALVES OF LAKE SUPERIOR. EXPECT WINDS TO DIMINISH ON THU...THEN GET CLOSE TO 25 KT AGAIN ON EASTERN LAKE SUPERIOR THU NIGHT AS LOW PRESSURE MOVES UP FROM SOUTH DAKOTA TO NEAR THUNDER BAY BY 8 AM FRI. LOOK FOR THIS LOW TO DEEPEN FRI AS IT HEADS TOWARDS JAMES BAY...BRINGING A COLD FRONT ACROSS LAKE SUPERIOR. NW WINDS OF 30 KT ARE POSSIBLE LATE FRI INTO FRI EVENING IN THE WAKE OF THE FRONT... PARTICULARLY ON EASTERN LAKE SUPERIOR. IF THE LOW IS A LITTLE DEEPER THAN EXPECTED...GALE FORCE WINDS COULD OCCUR DURING THIS TIME. AFTER FRI EVENING...WINDS WILL DIMINISH TO BELOW 20 KT AND REMAIN THROUGH SUN AS HIGH PRESSURE BUILDS IN FROM THE NW. && .MQT WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVY MIZ001-003-005 && $$ DISCUSSION...JLB AVIATION/MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 127 AM EDT WED SEP 5 2007 UPDATED AVIATION SECTION FOR 06Z TAF ISSUANCE .UPDATE... ISSUED DENSE FOG ADVY FOR MQT COUNTY WITH VSBYS OVER THE HIER TERRAIN AOB 1/4SM ATTM. EXPECT THE DENSE FOG TO BECOME MORE WDSPRD OVER MORE OF MQT COUNTY LATER AND ACRS MUCH OF THE REST OF INTERIOR WCNTRL UPR MI WITH ARRIVAL OF MID LVL DRYING/CAPPING IN THE WAKE OF H85 WARM FROPA WHILE SFC BNDRY REMAINS TO THE S AND INVRN BECOMES MORE SHALLOW WITH TIME. NO OTHER SITES ARE REPORTING LO VSBYS ATTM...SO WL HOLD OFF ON ADDITIONAL ADVYS FOR A FEW HRS TO SEE HOW FOG DVLPS. BUT EXPECT ADVYS WL BE EVENTUALLY NEEDED FOR AT LEAST ALL THE CNTRL COUNTIES FM IMT-IRON RIVER TO THE KEWEENAW AS MID LVL DRYING OVERSPREADS LLVL MSTR. THE H85 WARM FNT CURRENTLY STRETCHES FM THE KEWEENAW ACRS NRN MQT COUNTY INTO THE ERN ZNS...AS MARKED BY AXIS OF ACCAS AS SHOWN ON VSBL STLT IMAGERY. LATEST RUC SHOWS H85 WARM FROPA ACRS THE E BY 09Z...SO CUT POPS ACRS THE FAR ERN ZNS AFT THAT TIME. DENSE FOG MAY DVLP OVER THE E LATE AS WELL FOLLOWING THIS FROPA. $$ .SHORT TERM (TONIGHT AND WEDNESDAY)... 12Z UPPER AIR ANALYSIS SHOWED TWO MAIN FEATURES PRODUCING THE HEAVY RAIN OVER UPR MI. FIRST WAS H85 WARM FRONT STRADDLING THE SOUTHERN U.P. A SFC WARM FRONT IS NOW JUST EDGING INTO SOUTHERN SECTIONS OF CNTRL UPR MI. SECOND MAIN FEATURE IS 130KT H3 JET OVR ONTARIO. EARLIER TODAY THIS JET WAS CLOSE ENOUGH TO ENHANCE LIFTING ALONG H85 FRONT DUE TO DIVERGENCE ALOFT AND HELPING TO INCREASE FGEN FORCING. THIS AFTN THE JET CONTINUES EAST AND FOR THE MOST PART THE PCPN IS ENDING ACROSS UPR MI. WHAT AN EVENT...FOR AT LEAST PORTIONS OF UPR MI...THIS TURNS OUT TO BE. ALREADY SET ALL TIME DAILY RECORD RAINFALL FOR ANY MONTH...NO LESS SEPTEMBER. PREVIOUS RECORD WAS 4.09 INCHES SET IN JUNE OF 1968. DAILY TOTAL THUS FAR...4.28 INCHES. MOST WE HAVE HEARD IS AROUND 5 INCHES OVR KEWEENAW PENINSULA AND IN EASTERN MQT COUNTY NEAR SKANDIA. A COMPLETE LIST OF TOTALS IS ON OUR WEB SITE AT WWW.WEATHER.GOV/MQT IN THE TOP NEWS OF THE DAY SECTION. AN OFFICIAL RECORD REPORT WILL BE ISSUED THIS EVENING WHEN THE EVENT IS FINISHED. MEANWHILE...NOT A DROP OF RAIN IN SOUTHERN MENOMINEE COUNTY. SO THE TIGHT GRADIENT GUIDANCE SHOWED YDY FOR THE EVENT WAS RIGHT ON. LOCALLY RUN WRF-ARW ALSO DID FAIRLY WELL WITH PCPN AMOUNTS. DO IN LARGE PART TO THE DROUGHT CONDITIONS FOR MOST OF THE SUMMER...THUS FAR...HAVE ONLY HAD REPORTS OF MINOR STREET FLOODING...GRAVEL ROAD WASHOUTS...AND HIGH WATER IN CULVERTS. NO MAJOR FLOODING REPORTED SO FAR. PRETTY AMAZING CONSIDERING VOLUME OF WATER THAT OCCURRED IN SUCH A SHORT PERIOD OF TIME. CURRENT RADAR TRENDS POINT TO ONLY ISOLATED POPS THROUGH THE OVERNIGHT...FOCUSED MAINLY IN THE EAST HALF OF THE CWA. LACK OF STRONG INFLOW INTO THE DECAYING H85 FRONT MINIMIZES THE THREAT OF HEAVY RAIN. CONCERNED THAT ON SOUTHERN EDGE OF CONVECTION THERE MAY BE A CHANCE OF ENHANCED CONVECTION DUE TO LINGERING STRONG DEEP LAYER SHEAR AND MLCAPES CLOSE TO 1500J/KG. THUS FAR...LACK OF MOIST INFLOW INTO THIS AREA IS LIMITING CONVECTION INTENSITY AND COVERAGE. MOVING ON INTO THE LATER EVENING...FOG MAY BECOME A PROBLEM. LOWER LEVEL MOISTURE REMAINS AND MID LEVEL DRYING IS BEGINNING TO TAKE SHAPE. INCLUDED AREAS OF DENSE FOG IN GRIDS. STILL ASSESSING THE NEED FOR AN ADVY. ALREADY SEEING DENSE FOG IN UPSLOPE AREAS OF NCNTRL UPR MI ATTM AT OUR OFFICE NEAR NEGAUNEE. FLIP THE SWITCH FOR THE WEATHER ON WED ONCE WARM FRONT MOVES THROUGH. SFC WINDS SWITCH TO THE SSW WHICH ALLOWS THE HEAT TO REALLY KICK IN. IN FACT...HARD TO BELIEVE I KNOW...BUT SETUP OF H85 TEMPS AROUND 20C AND WSW WINDS (GFS/NAM/UKMET) APPEARS QUITE FAVORABLE FOR WIDESPREAD AROUND 90 READINGS TO OCCUR WED AFTN AWAY FM MODERATION OF LK MICHIGAN. DOWNSLOPING AREAS NEAR LK SUPERIOR (BARAGA TO MARQUETTE TO MUNISING) MAY TRY TO REACH MID 90S. NOT BAD WHEN LOW END OF ENSEMBLE MEAN SHOWS UPR 80S. ALL GUIDANCE IN REALLY GOOD AGREEMENT TO A HOT AND FAIRLY HUMID (DEWPOINTS IN THE LWR 60S) EARLY SEPTEMBER DAY. RECORD HIGH AT NWS MQT OF 88 SET IN 1998 LOOKS IN SERIOUS JEOPARDY. && .LONG TERM (WEDNESDAY NIGHT THROUGH TUESDAY)... TAKING A GLIMPSE AT THE UPPER LEVEL PATTERN...RIDGING WILL START OUT THE PERIOD. IN FACT...RIDGING SHOULD DOMINATE THE EASTERN TWO-THIRDS OF THE NATION. FARTHER TO OUR SOUTH...WE WILL BE WATCHING THE PROGRESSION ON A SHORTWAVE SLIDE NORTHEASTWARD FROM OKLAHOMA AND NEBRASKA...AS IT GETS SCOOPED UP IN THE SOUTHWESTERLY FLOW NEAR US. STILL...THIS IN COMBINATION WITH THE NEXT SHORTWAVE MOVING IN FROM THE WEST...SHOULD BRING OUR NEXT SHOT OF PRECIPITATION TO THE UPPER PENINSULA. AT THE SURFACE...THERE ARE SOME MINOR DISCREPANCIES ON THE THE LOCATION OF THE SURFACE LOW BY 12Z FRIDAY. IN GENERAL...THE SURFACE LOW SHOULD STRETCH FROM CENTRAL ONTARIO SOUTHEASTWARD THROUGH NORTHERN IOWA. UPPER PENINSULA MAINLY STAYS IN THE WARM SLOT UNTIL LATE THURSDAY NIGHT AND DURING THE DAY FRIDAY...WITH THE BEST CHANCE OF SIGNIFICANT RAIN WITH THE PASSAGE OF THE COLD FRONT DURING THE DAYLIGHT HOURS FRIDAY. MAY NEED TO BUMP UP AFTERNOON HIGHS FOR THURSDAY A COUPLE OF MORE DEGREES DEPENDING ON THE STRENGTH AND TIMING OF THE LOW...BUT WILL STICK TO THE LOW TO MID 80S FOR NOW. TEMPERATURES WILL BE KNOCKED DOWN AFTER THIS SYSTEM...WITH HIGHS THROUGH THE REMAINDER OF THE PERIOD IN THE 60S. CLIMATOLOGICALLY...NORMAL HIGH TEMPERATURES FOR THIS TIME OF THE YEAR RIGHT AROUND 70 DEGREES FOR THE MARQUETTE AREA. AS FOR THE EXTENDED FORECAST...DAYS 4 TO 7...SATURDAY THROUGH TUESDAY...HAVE GENERALLY FOLLOWED HPC GUIDANCE. HPC UTILIZED A COMPROMISE SOLUTION WITH THE 00Z NCEP-GEFS AND ECMWF. BASICALLY THIS RESULTED IN A CONTINUED LOW PROBABILITY POP FOR MUCH OF THE EXTENDED...AS THE LARGE 500MB TROUGH REMAINS ENTRENCHED OVER THE NORTHERN TIER OF THE NATION. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT DENSE FOG/IFR VSBYS/CIGS TO LINGER AS UPR LVL DRYING/CAPPING IN WAKE OF H85 WARM FROPA MOVES OVER LINGERING LLVL MSTR/SHALLOW FNTL INVRN. CONDITIONS SHOULD IMPROVE DRAMATICALLY TO VFR WED MRNG ONCE SFC WARM FNT SHIFTS TO THE N. DIURNAL MIXING WL ALLOW DVLPMNT OF GUSTY SW WINDS...ESPECIALLY AT SAW. LOOK FOR LLWS ONCE SUN SETS AND LLJ UNDERGOES NOCTURNAL INTENSIFICATION ABV RADIATION INVRN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRES OVER NORTHEAST ONTARIO WILL BUILD INTO QUEBEC TONIGHT AS A WARM FRONT LIFTS SLOWLY INTO SOUTHERN UPR MI. GUSTY E WINDS TO 25 KT ON LK SUPERIOR WILL DIMINISH BY WED MORNING. ANOTHER BOUT OF STRONG WINDS...THIS TIME FROM THE SOUTH...EXPECTED WED NIGHT INTO THU AHEAD OF TROUGH THAT SHIFTS EAST OUT OF DAKOTAS. SOME GUSTS TO 30 KT ARE POSSIBLE ON THE FAVORED EASTERN LAKE. MORE STRONG SOUTH WINDS POSSIBLE FRI NIGHT AS SFC LOW SHIFTS ACROSS UPR LAKES. WINDS TURNING TO THE NE ON SAT IN THE WAKE OF THE LOW COULD APPROACH 30 KT. NO GALE FORCE WINDS ARE EXPECTED THE ENTIRE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVY MIZ001-003-005 && $$ UPDATE...KC SHORT TERM...JLA LONG TERM...KF AVIATION...KC MARINE...JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 327 AM CDT WED SEP 5 2007 .SHORT TERM... UPPER LOW THAT WAS OVER WEST TEXAS LAST NIGHT HAS MOVED INTO WESTERN OKLAHOMA THIS MORNING. A SMALL JET STREAK IS MOVING EAST ACROSS WEST TEXAS FROM THE DAVIS MOUNTAINS INTO THE NORTHERN EDWARDS PLATEAU...AS SEEN BY ENHANCED UPPER LEVEL CLOUDS IN WV/IR IMAGERY. RUC80 ANALYZES THIS FEATURE AS WELL...AND SHOWER/THUNDERSTORM ACTIVITY CONTINUES TO DEVELOP ON THE NOSE OF THIS FEATURE JUST EAST OF OUR AREA. THESE STORMS SHOULD CONTINUE TO PUSH EAST AWAY FROM OUR AREA THROUGH THE REST OF THE MORNING. WITH THIS IN MIND...HAVE GONE AHEAD AND CANCELED THE FLASH FLOOD WATCH FOR THE REST OF THE MORNING SINCE THE HEAVY RAIN THREAT IS EAST OF OUR CWA. THE JEST STREAK MAY RESULT IN SOME SHOWERS OVER THE SOUTHERN HALF OF OUR CWA THIS MORNING...SO WILL KEEP A CHANCE OF SHRA/TSRA THERE TODAY...MAINLY FOR THE MORNING HOURS. MID/UPPER LEVEL CLOUDS WILL BE AROUND AGAIN TODAY AS MOISTURE STREAMS TO THE EAST/NORTHEAST FROM HENRIETTE. WE ALSO HAVE LOW CLOUDS DEVELOPING UNDER CLEAR SKIES OVER OUR NORTHERN CWA...AND EXPECT THESE TO ERODE THROUGH THE MORNING HOURS. SAW TEMPERATURES REACH 80 OR WARMER IN AREAS THAT DIDN/T SEE RAIN YESTERDAY...AND HAVE KEPT THE WARMING TREND FOR TODAY AS LESS RAIN IS EXPECTED TODAY. CONTINUE TO TREND POPS DOWNWARD TONIGHT...KEEPING ONLY SLIGHT CHANCE POPS IN FOR SOUTHERN AND EASTERN AREAS. WITH MOISTURE CONTINUING TO STREAM NORTHWARD AT LOW LEVELS...AND MOISTURE ALOFT FROM HENRIETTE...CANNOT RULE OUT SOME SHOWERS FOR SOUTHERN AREAS. .LONG TERM... HENRIETTE IS EXPECTED TO CONTINUE ON A NORTHWARD TRACK INTO WESTERN NEW MEXICO BY TOMORROW. HOWEVER...THERE IS ENOUGH UNCERTAINTY ABOUT THE EXACT POSITION OF THE STORM TO KEEP SLIGHT CHANCE POPS GOING FOR WESTERN AREAS OF THE CWA. MOST OF THE RELATED ACTIVITY FROM HENRIETTE IS EXPECTED TO BE WEST AND NORTH OF OUR CWA...BUT THE BIG COUNTRY...ALONG AND NORTH OF INTERSTATE 20 COULD SEE SOME PRECIPITATION THURSDAY INTO FRIDAY AS THE STORM IS ABSORBED INTO THE MEAN WESTERLY FLOW...THEN ACCELERATES TO THE NORTHEAST ACROSS WESTERN OKLAHOMA AND SOUTHERN KANSAS THURSDAY NIGHT. HENRIETTE IS EXPECTED TO BE PICKED UP AND PULLED NORTHWARD BY AN UPPER LOW THAT WILL BE EJECTING TO THE EAST OUT OF THE INTERMOUNTAIN WEST THURSDAY/THURSDAY NIGHT. GFS CONTINUES TO SHOW A WEAK COLD FRONT/WIND SHIFT PUSHING INTO THE BIG COUNTRY BEHIND THIS LOW FRIDAY INTO SATURDAY. SO HAVE KEPT LOW ORDER CHANCE AND SLIGHT CHANCE POPS GOING FOR THE AREA THROUGH THE WEEKEND ALONG THE POSSIBLE STAGNANT BOUNDARY. AS THE BOUNDARY LIFTS BACK TO THE NORTH LATE IN THE WEEKEND AND EARLY NEXT WEEK...WE COULD CONTINUE TO SEE A CHANCE FOR SHOWERS AND THUNDERSTORMS...SO WILL KEEP THE LOW ORDER POPS IN THROUGH SUNDAY NIGHT. AFTER THAT HAVE TAKEN RAIN CHANCES OUT AS THE RIDGE BECOMES BETTER ESTABLISHED OVER THE SOUTHERN PLAINS. HAVE NOT MADE MANY CHANGES TO TEMPERATURES IN THE EXTENDED FORECAST WITH NEAR NORMAL READINGS EXPECTED. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 86 70 88 73 / 20 10 20 20 SAN ANGELO 89 72 89 72 / 20 10 10 10 JUNCTION 86 72 88 74 / 40 20 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 20 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 401 AM CDT WED SEP 5 2007 .DISCUSSION...FCST FOCUS ON WARM DAY TODAY WITH PATTERN BECOMING WET AND UNSETTLED FOR THU INTO FRI TIME FRAME. SFC/MID LEVEL RIDGING EXPECTED TO DOMINATE TODAY. WATCHING MOISTURE TO OUR SOUTH ON WATER VAPOR. RUC SHOWS A FEW WEAK VORT CENTERS VCNTY KS/MO WITH STRONGEST VORT ACTION FURTHER SOUTH ACRS OK/TX. WITH PCPN ONGOING AND DEFYING THE DIURNALLY DRIVEN IDEA THERE IS SOME CONCERN FOR PCPN REACHING FAR SOUTH LATRER TNGT...HOWEVER FOR NOW FEEL INCLINED TO KEEP THE DRY LOOK GOING. GUID POPS ARE A SMIDGE WORRISOME FOR MENTIONING A SML CHC BUT WILL KEEP THINGS PRETTY GRID WISE...LEANING TOWARDS QUIETER GUID POPS AND HPC QPF AND STAY DRY. FAIRLY MOIST SW H8 FLOW SETTING UP FOR THU...H8 DEWS GETTING TO NR 14C. A BIT MORE DYNAMICS IN PLACE WITH H5 WAVES SHOWING A LITTLE MORE STEAM AND CWA IN LEFT NOSE VCNTY OF H8 WIND MAX. GFS MOS DEW POINTS GET REAL JUICY INTO THE MID 70S...SURPRISINGLY MORE ROBUST THAN NAM MOS. WHILE WEAK UPR DVRG NOTED THU...THE BETTER UPPER FORCING IMPINGES UPON THE CWA FRI WITH ARRIVAL OF PLAINS SHORTWAVE. H8 LLJ CRANKS UP TO 40 TO 50 KNOTS THU NGT/FRI MRNG AHEAD OF H8 TROUGH. HAVE DECIDED TO GO LIKELY FOR THU THROUGH FRI TIME PERIOD. THE GFS SHOWS A BELIEVEABLE WAVE IN THE FLOW FOR SATURDAY WITH A SURFACE REFLECTION TO OUR SE. THIS WOULD CLIP THE SE WITH PCPN. WILL JUST GO WITH A CHC CWA WIDE TO ACCOUNT FOR THE UPPER FEATURE. 00Z ECMWF BACKING OFF ON PCPN FOR SUNDAY WITH LESS SHORTWAVE ENERGY NOTED THAN THE PRIOR 12Z RUN. THIS NEW TREND SUPPORTS THE SIGNALS FROM THE GFS FOR A DRIER SUNDAY...WITH ONLY TEEN POPS AND CLR-PC SKIES. && 10 .AVIATION...VAD WINDS FROM LOWEST GATES THROUGH 1000M FROM THE SOUTHWEST AT 20KTS PREVENTING WIDESPREAD DENSE FOG. EXPECT CONDITIONS TO PERSIST THROUGH 14Z...SO ONLY LIGHT FOG WITH VSBYS GENERALLY ABV MVFR PSBL AT TAF SITES. DEWPT DEPRESSIONS STILL 8 DEGREES. INCRNG SOUTH WINDS WL CARRY DEEPER MOISTURE RAPIDLY ACRS SRN WI TNGT. EXPC MID LVL CLOUDS TO SWEEP IN BY 06Z. NOT OUT OF THE QUESTION THAT MVFR CIGS AND LGT FOG REACHES TAF SITES BY LATE IN THE PD WITH SCT -SHRA IN RESPONSE TO WEAK S/W TROUGH MOVING THRU SRN WI. && .MKX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ wi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1205 PM EDT WED SEP 5 2007 .DISCUSSION (ISSUED AT 935 AM EDT WED SEP 5 2007)... UPDATED THE ZFP AND OTHER PRODUCTS TO GET RID OF THE MENTION OF FOG...AND TO ADD SLIGHT CHANCE POPS TO PORTIONS OF THE EASTERN CWA AS SHOWERS BEGAN TO POP UP AROUND 12Z OVER LAKE SUPERIOR AND SLIDE INLAND. WILL BE ADDING FOG TO AREAS OF LAKE SUPERIOR AS WELL. OTHERWISE...FEW OTHER CHANGES WERE MADE FOR THE MORNING UPDATE. && .PREVIOUS DISCUSSION (ISSUED AT 445 AM EDT WED SEP 5 2007)... MAIN FCST CONCERNS ARE PCPN CHANCES THU THROUGH FRI. WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER THE SE AND CENTRAL CONUS BETWEEN TROUGHS OVER OR/ID/NV AND ERN CANADA RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. A SHORTWAVE AND PLENTIFUL DEEP MOISTURE WAS SLOWLY LIFTING NE FROM OK/AR TOWARD THE MID MS VALLEY. SHRA/TSRA EXITING ERN UPPER MI WERE SUPPORTED BY 850-700 MB FGEN AND CONTINUED WRLY FLOW ISENTROPIC LIFT ALONG THE 850 MB WARM FRONT. A WEAKER BAND OF SHRA HAD ALSO DEVELOPED INTO WRN MENOMINEE COUNTY ALIGNED WITH ANOTHER AREA OF WEAK TO MODERATE 310K-315K ISENTROPIC ASCENT...PER 06Z NAM. AT THE SFC...A FRONT EXTENDED THROUGH CNTRL MN AND NRN WI FROM LOW PRES OVER SE MT. EXTENSIVE LOW CLOUDS AND FOG PREVAILED NORTH OF THE FRONT...ACROSS UPPER MI AND LAKE SUPERIOR WHERE VSBY HAD DROPPED TO AROUND 1/4SM IN SEVERAL LOCATIONS. TODAY...EXPECT THE REMAINING SHRA/TSRA OVER S UPPER MI AND SUPPORTING LIFT TO SLIDE EASTWARD WITH THE PCPN ENDING BY AROUND 12Z. A SHORTWAVE TROUGH AND LOW PRES MOVING FROM MANITOBA TO HUDSON BAY WILL HELP DRAW A WARM FRONT THROUGH UPPER MI AS SW 925 MB WINDS INCREASE TO 20-30 KT. UPSTREAM MAX READINGS FROM TUE OVER ERN MN AND NW WI ALONG WITH MIXING TO 850-800 MB (850 MB TEMPS AROUND 20C) SUPPORT MAX READINGS AROUND 90F OVER MUCH OF THE WEST HALF OF UPPER MI...ESPECIALLY WHERE DOWNSLOPE FLOW PREVAILS. LAKE MI MODIFIED AIR WILL KEEP THE ERN CWA A BIT COOLER. NO ADDITIONAL PCPN IS EXPECTED WITH SUBSTANTIAL CAPPING IN THE WARM SECTOR PREVAILING...DESPITE SIGNIFICANT LOW LEVEL MOISTURE...DEWPOINTS IN THE LOW TO MID 60S. TONIGHT AND THU...THE ACTIVE FRONTAL/BAROCLINIC ZONE WILL SET UP NORTH OF THE AREA...FROM NW MN INTO WRN ONTARIO AND MAY GRADUALLY SAG INTO NRN LAKE SUPERIOR...PER 00Z GFS. HOWEVER...EXPECT THE BULK OF THE OCNLY HEAVY SHRA/TSRA SUPPORTED BY STRONG 850-600 MB FGEN TO REMAIN N OF UPPER MI...PER MDLS CONSENSUS. HOWEVER...THE SHRTWV AND MOISTURE PLUME FROM THE MS VALLEY MAY EVENTUALLY SPREAD INTO UPPER MI WITH THE POTENTIAL FOR SCT/ISOLD IN THE AFTERNOON. THE GFS/CMC/UKMET WOULD PLACE THE GREATER PCPN CHANCES WITH THIS SYSTEM OVER THE S AND E PORTIONS OF THE CWA. THU NIGHT INTO FRI...AS THE MID LEVEL TROF MOVES FROM THE NRN PLAINS INTO THE UPPER MS VALLEY THE SFC LOW WILL LIFT NE FROM SD THROUGH NRN MN INTO NRN ONTARIO DRAGGING A COLD FRONT ACROSS UPPER MI ON FRI. THE INCREASING MOISTURE IN THE WARM SECTOR ALONG WITH THE POTENTIAL FOR WEAK SHRTWVS IN SW FLOW STILL COULD SET OFF SOME SHRA/TSRA THU NIGHT. HOWEVER...THE BEST CHANCE FOR SHRA/TSRA IS EXPECTED WITH THE FROPA AND MID LEVEL TROF PASSAGE ON FRI. DECENT LOW LEVEL CONV ALONG THE FRONT ALONG WITH MODERATE UPPER LEVEL DIV AND QVECTOR CONV JUSTIFY LIKELY POPS. CAPE VALUES NEAR 1K J/KG AND 40-50 KT 0-6KM SHEAR COULD SUPPORT SOME STRONGER TO MARGINALLY SEVERE STORMS...ESPECIALLY IF CONVECTION IS DELAYED INTO THE AFTERNOON. FRI NIGHT AND SAT...ANY LEFTOVER SHRA/TSRA WILL END QUICKLY FRI EVENING WITH STRONG DRYING MOVING IN ON BRISK NW WINDS BEHIND THE COLD FRONT. EVEN THOUGH THERE MAY BE ADDITIONAL WEAK SHORTWAVES IN WITH THE DEVELOPING BROAD TROUGHING OVER THE NRN CONUS...WITH LIMITED MOISTURE AND WEAK DYNAMIC SUPPORT...ONLY SLIGHT CHANCE POPS WERE MENTIONED OVER THE SW PORTION OF THE CWA. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... A COLD FRONT APPROACHING FROM THE DAKOTAS COMBINED WITH THE SETTING OF THE SUN WILL ALLOW FOR A LOW LEVEL JET TO DEVELOP ACROSS UPPER MICHIGAN AFTER 00Z. THUS...LLWS WAS INCLUDED FOR BOTH TAF SITES THROUGH 12Z WHEN SURFACE WIND GUSTS SHOULD BE INCREASING ONCE AGAIN. OTHERWISE...GOOD CEIGS AND VIS ARE EXPECTED THOUGH THE NEXT 24 HOURS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A COLD FRONT OVER THE DAKOTAS WILL MOVE INTO THE MN ARROWHEAD LATE TONIGHT. AHEAD OF THE FRONT...WINDS MAY GUST UP TO 30 KT TONIGHT ON BOTH HALVES OF LAKE SUPERIOR. EXPECT WINDS TO DIMINISH ON THU...THEN GET CLOSE TO 25 KT AGAIN ON EASTERN LAKE SUPERIOR THU NIGHT AS LOW PRESSURE MOVES UP FROM SOUTH DAKOTA TO NEAR THUNDER BAY BY 8 AM FRI. LOOK FOR THIS LOW TO DEEPEN FRI AS IT HEADS TOWARDS JAMES BAY...BRINGING A COLD FRONT ACROSS LAKE SUPERIOR. NW WINDS OF 30 KT ARE POSSIBLE LATE FRI INTO FRI EVENING IN THE WAKE OF THE FRONT... PARTICULARLY ON EASTERN LAKE SUPERIOR. IF THE LOW IS A LITTLE DEEPER THAN EXPECTED...GALE FORCE WINDS COULD OCCUR DURING THIS TIME. AFTER FRI EVENING...WINDS WILL DIMINISH TO BELOW 20 KT AND REMAIN THROUGH SUN AS HIGH PRESSURE BUILDS IN FROM THE NW. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KF PREVIOUS DISCUSSION...JLB AVIATION...KF MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 935 AM EDT WED SEP 5 2007 .DISCUSSION... UPDATED THE ZFP AND OTHER PRODUCTS TO GET RID OF THE MENTION OF FOG...AND TO ADD SLIGHT CHANCE POPS TO PORTIONS OF THE EASTERN CWA AS SHOWERS BEGAN TO POP UP AROUND 12Z OVER LAKE SUPERIOR AND SLIDE INLAND. WILL BE ADDING FOG TO AREAS OF LAKE SUPERIOR AS WELL. OTHERWISE...FEW OTHER CHANGES WERE MADE FOR THE MORNING UPDATE. && .PREVIOUS DISCUSSION (ISSUED AT 445 AM EDT WED SEP 5 2007)... MAIN FCST CONCERNS ARE PCPN CHANCES THU THROUGH FRI. WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER THE SE AND CENTRAL CONUS BETWEEN TROUGHS OVER OR/ID/NV AND ERN CANADA RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. A SHORTWAVE AND PLENTIFUL DEEP MOISTURE WAS SLOWLY LIFTING NE FROM OK/AR TOWARD THE MID MS VALLEY. SHRA/TSRA EXITING ERN UPPER MI WERE SUPPORTED BY 850-700 MB FGEN AND CONTINUED WRLY FLOW ISENTROPIC LIFT ALONG THE 850 MB WARM FRONT. A WEAKER BAND OF SHRA HAD ALSO DEVELOPED INTO WRN MENOMINEE COUNTY ALIGNED WITH ANOTHER AREA OF WEAK TO MODERATE 310K-315K ISENTROPIC ASCENT...PER 06Z NAM. AT THE SFC...A FRONT EXTENDED THROUGH CNTRL MN AND NRN WI FROM LOW PRES OVER SE MT. EXTENSIVE LOW CLOUDS AND FOG PREVAILED NORTH OF THE FRONT...ACROSS UPPER MI AND LAKE SUPERIOR WHERE VSBYS HAD DROPPED TO AROUND 1/4SM IN SEVERAL LOCATIONS. TODAY...EXPECT THE REMAINING SHRA/TSRA OVER S UPPER MI AND SUPPORTING LIFT TO SLIDE EASTWARD WITH THE PCPN ENDING BY AROUND 12Z. A SHORTWAVE TROUGH AND LOW PRES MOVING FROM MANITOBA TO HUDSON BAY WILL HELP DRAW A WARM FRONT THROUGH UPPER MI AS SW 925 MB WINDS INCREASE TO 20-30 KT. UPSTREAM MAX READINGS FROM TUE OVER ERN MN AND NW WI ALONG WITH MIXING TO 850-800 MB (850 MB TEMPS AROUND 20C) SUPPORT MAX READINGS AROUND 90F OVER MUCH OF THE WEST HALF OF UPPER MI...ESPECIALLY WHERE DOWNSLOPE FLOW PREVAILS. LAKE MI MODIFIED AIR WILL KEEP THE ERN CWA A BIT COOLER. NO ADDITIONAL PCPN IS EXPECTED WITH SUBSTANTIAL CAPPING IN THE WARM SECTOR PREVAILING...DESPITE SIGNIFICANT LOW LEVEL MOISTURE...DEWPOINTS IN THE LOW TO MID 60S. TONIGHT AND THU...THE ACTIVE FRONTAL/BAROCLINIC ZONE WILL SET UP NORTH OF THE AREA...FROM NW MN INTO WRN ONTARIO AND MAY GRADUALLY SAG INTO NRN LAKE SUPERIOR...PER 00Z GFS. HOWEVER...EXPECT THE BULK OF THE OCNLY HEAVY SHRA/TSRA SUPPORTED BY STRONG 850-600 MB FGEN TO REMAIN N OF UPPER MI...PER MDLS CONSENSUS. HOWEVER...THE SHRTWV AND MOISTURE PLUME FROM THE MS VALLEY MAY EVENTUALLY SPREAD INTO UPPER MI WITH THE POTENTIAL FOR SCT/ISOLD IN THE AFTERNOON. THE GFS/CMC/UKMET WOULD PLACE THE GREATER PCPN CHANCES WITH THIS SYSTEM OVER THE S AND E PORTIONS OF THE CWA. THU NIGHT INTO FRI...AS THE MID LEVEL TROF MOVES FROM THE NRN PLAINS INTO THE UPPER MS VALLEY THE SFC LOW WILL LIFT NE FROM SD THROUGH NRN MN INTO NRN ONTARIO DRAGGING A COLD FRONT ACROSS UPPER MI ON FRI. THE INCREASING MOISTURE IN THE WARM SECTOR ALONG WITH THE POTENTIAL FOR WEAK SHRTWVS IN SW FLOW STILL COULD SET OFF SOME SHRA/TSRA THU NIGHT. HOWEVER...THE BEST CHANCE FOR SHRA/TSRA IS EXPECTED WITH THE FROPA AND MID LEVEL TROF PASSAGE ON FRI. DECENT LOW LEVEL CONV ALONG THE FRONT ALONG WITH MODERATE UPPER LEVEL DIV AND QVECTOR CONV JUSTIFY LIKELY POPS. CAPE VALUES NEAR 1K J/KG AND 40-50 KT 0-6KM SHEAR COULD SUPPORT SOME STRONGER TO MARGINALLY SEVERE STORMS...ESPECIALLY IF CONVECTION IS DELAYED INTO THE AFTERNOON. FRI NIGHT AND SAT...ANY LEFTOVER SHRA/TSRA WILL END QUICKLY FRI EVENING WITH STRONG DRYING MOVING IN ON BRISK NW WINDS BEHIND THE COLD FRONT. EVEN THOUGH THERE MAY BE ADDITIONAL WEAK SHORTWAVES IN WITH THE DEVELOPING BROAD TROUGHING OVER THE NRN CONUS...WITH LIMITED MOISTURE AND WEAK DYNAMIC SUPPORT...ONLY SLIGHT CHANCE POPS WERE MENTIONED OVER THE SW PORTION OF THE CWA. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... FOG AND LOW CIGS WILL DISSIPATE BY 14Z AT BOTH TAF SITES DUE TO DAYTIME HEATING AND SOUTHWEST WINDS PICKING UP. IN FACT...THE WINDS WILL LIKELY GUST THIS AFTERNOON AS DAYTIME HEATING BRINGS DOWN HIGHER WINDS FROM ABOVE THE SFC. A COLD FRONT APPROACHING FROM THE DAKOTAS COMBINED WITH THE SETTING OF THE SUN WILL ALLOW FOR A LOW LEVEL JET TO DEVELOP ACROSS UPPER MICHIGAN. THUS...LLWS IS INCLUDED FOR BOTH TAF SITES. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A COLD FRONT OVER THE DAKOTAS WILL MOVE INTO THE MN ARROWHEAD LATE TONIGHT. AHEAD OF THE FRONT...WINDS MAY GUST UP TO 30 KT TONIGHT ON BOTH HALVES OF LAKE SUPERIOR. EXPECT WINDS TO DIMINISH ON THU...THEN GET CLOSE TO 25 KT AGAIN ON EASTERN LAKE SUPERIOR THU NIGHT AS LOW PRESSURE MOVES UP FROM SOUTH DAKOTA TO NEAR THUNDER BAY BY 8 AM FRI. LOOK FOR THIS LOW TO DEEPEN FRI AS IT HEADS TOWARDS JAMES BAY...BRINGING A COLD FRONT ACROSS LAKE SUPERIOR. NW WINDS OF 30 KT ARE POSSIBLE LATE FRI INTO FRI EVENING IN THE WAKE OF THE FRONT... PARTICULARLY ON EASTERN LAKE SUPERIOR. IF THE LOW IS A LITTLE DEEPER THAN EXPECTED...GALE FORCE WINDS COULD OCCUR DURING THIS TIME. AFTER FRI EVENING...WINDS WILL DIMINISH TO BELOW 20 KT AND REMAIN THROUGH SUN AS HIGH PRESSURE BUILDS IN FROM THE NW. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KF PREVIOUS DISCUSSION...JLB AVIATION...AJ MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 703 AM EDT WED SEP 5 2007 UPDATED AVIATION SECTION FOR 12Z TAF ISSUANCE .DISCUSSION... MAIN FCST CONCERNS ARE PCPN CHANCES THU THROUGH FRI. WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL RIDGE OVER THE SE AND CENTRAL CONUS BETWEEN TROUGHS OVER OR/ID/NV AND ERN CANADA RESULTING IN WNW FLOW THROUGH THE NRN GREAT LAKES. A SHORTWAVE AND PLENTIFUL DEEP MOISTURE WAS SLOWLY LIFTING NE FROM OK/AR TOWARD THE MID MS VALLEY. SHRA/TSRA EXITING ERN UPPER MI WERE SUPPORTED BY 850-700 MB FGEN AND CONTINUED WRLY FLOW ISENTROPIC LIFT ALONG THE 850 MB WARM FRONT. A WEAKER BAND OF SHRA HAD ALSO DEVELOPED INTO WRN MENOMINEE COUNTY ALIGNED WITH ANOTHER AREA OF WEAK TO MODERATE 310K-315K ISENTROPIC ASCENT...PER 06Z NAM. AT THE SFC...A FRONT EXTENDED THROUGH CNTRL MN AND NRN WI FROM LOW PRES OVER SE MT. EXTENSIVE LOW CLOUDS AND FOG PREVAILED NORTH OF THE FRONT...ACROSS UPPER MI AND LAKE SUPERIOR WHERE VSBYS HAD DROPPED TO AROUND 1/4SM IN SEVERAL LOCATIONS. TODAY...EXPECT THE REMAINING SHRA/TSRA OVER S UPPER MI AND SUPPORTING LIFT TO SLIDE EASTWARD WITH THE PCPN ENDING BY AROUND 12Z. A SHORTWAVE TROUGH AND LOW PRES MOVING FROM MANITOBA TO HUDSON BAY WILL HELP DRAW A WARM FRONT THROUGH UPPER MI AS SW 925 MB WINDS INCREASE TO 20-30 KT. UPSTREAM MAX READINGS FROM TUE OVER ERN MN AND NW WI ALONG WITH MIXING TO 850-800 MB (850 MB TEMPS AROUND 20C) SUPPORT MAX READINGS AROUND 90F OVER MUCH OF THE WEST HALF OF UPPER MI...ESPECIALLY WHERE DOWNSLOPE FLOW PREVAILS. LAKE MI MODIFIED AIR WILL KEEP THE ERN CWA A BIT COOLER. NO ADDITIONAL PCPN IS EXPECTED WITH SUBSTANTIAL CAPPING IN THE WARM SECTOR PREVAILING...DESPITE SIGNIFICANT LOW LEVEL MOISTURE...DEWPOINTS IN THE LOW TO MID 60S. TONIGHT AND THU...THE ACTIVE FRONTAL/BAROCLINIC ZONE WILL SET UP NORTH OF THE AREA...FROM NW MN INTO WRN ONTARIO AND MAY GRADUALLY SAG INTO NRN LAKE SUPERIOR...PER 00Z GFS. HOWEVER...EXPECT THE BULK OF THE OCNLY HEAVY SHRA/TSRA SUPPORTED BY STRONG 850-600 MB FGEN TO REMAIN N OF UPPER MI...PER MDLS CONSENSUS. HOWEVER...THE SHRTWV AND MOISTURE PLUME FROM THE MS VALLEY MAY EVENTUALLY SPREAD INTO UPPER MI WITH THE POTENTIAL FOR SCT/ISOLD IN THE AFTERNOON. THE GFS/CMC/UKMET WOULD PLACE THE GREATER PCPN CHANCES WITH THIS SYSTEM OVER THE S AND E PORTIONS OF THE CWA. THU NIGHT INTO FRI...AS THE MID LEVEL TROF MOVES FROM THE NRN PLAINS INTO THE UPPER MS VALLEY THE SFC LOW WILL LIFT NE FROM SD THROUGH NRN MN INTO NRN ONTARIO DRAGGING A COLD FRONT ACROSS UPPER MI ON FRI. THE INCREASING MOISTURE IN THE WARM SECTOR ALONG WITH THE POTENTIAL FOR WEAK SHRTWVS IN SW FLOW STILL COULD SET OFF SOME SHRA/TSRA THU NIGHT. HOWEVER...THE BEST CHANCE FOR SHRA/TSRA IS EXPECTED WITH THE FROPA AND MID LEVEL TROF PASSAGE ON FRI. DECENT LOW LEVEL CONV ALONG THE FRONT ALONG WITH MODERATE UPPER LEVEL DIV AND QVECTOR CONV JUSTIFY LIKELY POPS. CAPE VALUES NEAR 1K J/KG AND 40-50 KT 0-6KM SHEAR COULD SUPPORT SOME STRONGER TO MARGINALLY SEVERE STORMS...ESPECIALLY IF CONVECTION IS DELAYED INTO THE AFTERNOON. FRI NIGHT AND SAT...ANY LEFTOVER SHRA/TSRA WILL END QUICKLY FRI EVENING WITH STRONG DRYING MOVING IN ON BRISK NW WINDS BEHIND THE COLD FRONT. EVEN THOUGH THERE MAY BE ADDITIONAL WEAK SHORTWAVES IN WITH THE DEVELOPING BROAD TROUGHING OVER THE NRN CONUS...WITH LIMITED MOISTURE AND WEAK DYNAMIC SUPPORT...ONLY SLIGHT CHANCE POPS WERE MENTIONED OVER THE SW PORTION OF THE CWA. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... FOG AND LOW CIGS WILL DISSIPATE BY 14Z AT BOTH TAF SITES DUE TO DAYTIME HEATING AND SOUTHWEST WINDS PICKING UP. IN FACT...THE WINDS WILL LIKELY GUST THIS AFTERNOON AS DAYTIME HEATING BRINGS DOWN HIGHER WINDS FROM ABOVE THE SFC. A COLD FRONT APPROACHING FROM THE DAKOTAS COMBINED WITH THE SETTING OF THE SUN WILL ALLOW FOR A LOW LEVEL JET TO DEVELOP ACROSS UPPER MICHIGAN. THUS...LLWS IS INCLUDED FOR BOTH TAF SITES. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A COLD FRONT OVER THE DAKOTAS WILL MOVE INTO THE MN ARROWHEAD LATE TONIGHT. AHEAD OF THE FRONT...WINDS MAY GUST UP TO 30 KT TONIGHT ON BOTH HALVES OF LAKE SUPERIOR. EXPECT WINDS TO DIMINISH ON THU...THEN GET CLOSE TO 25 KT AGAIN ON EASTERN LAKE SUPERIOR THU NIGHT AS LOW PRESSURE MOVES UP FROM SOUTH DAKOTA TO NEAR THUNDER BAY BY 8 AM FRI. LOOK FOR THIS LOW TO DEEPEN FRI AS IT HEADS TOWARDS JAMES BAY...BRINGING A COLD FRONT ACROSS LAKE SUPERIOR. NW WINDS OF 30 KT ARE POSSIBLE LATE FRI INTO FRI EVENING IN THE WAKE OF THE FRONT... PARTICULARLY ON EASTERN LAKE SUPERIOR. IF THE LOW IS A LITTLE DEEPER THAN EXPECTED...GALE FORCE WINDS COULD OCCUR DURING THIS TIME. AFTER FRI EVENING...WINDS WILL DIMINISH TO BELOW 20 KT AND REMAIN THROUGH SUN AS HIGH PRESSURE BUILDS IN FROM THE NW. && .MQT WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVY MIZ001-003-005 && $$ DISCUSSION...JLB AVIATION/MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 1016 AM CDT WED SEP 5 2007 .UPDATE...MINOR UPWARD ADJUSTMENTS TO POPS AND CLOUDS OVER THE DELTA REGION AS UPSTREAM RAINS BECOMING MORE CERTAIN FOR THOSE LOCATIONS THROUGH THE AFTERNOON HOURS. 12Z RUC BREAKS OUT SHRA/TSRA ALONG MS RIVER BY 18Z AND THEN SPREADS ACTIVITY SLOWLY EWD TO I-55 CORRIDOR WHILE KEEPING ERN MS MOSTLY DRY. MORNING SATELLITE IMAGERY HAS BEEN SHOWING MID-UPPER LEVEL CLOUDS THINNING RAPIDLY AS THEY PROGRESS EWD THROUGH THE CWFA. MORNING RAOBS SHOW ONLY A SLIGHT CATEGORY FOR WET MICROBURST ACTIVITY...MAINLY SWRN PORTIONS OF CWFA THIS AFTERNOON. THE UPPER VORT CENTER IN OK WITH TROUGH AXIS SWD INTO ERN TX NOW LIFTING NEWD AND SHOULD DRAG MORE UVV ACROSS OUR REGION DURING THE EVENING HOURS BRINGING A BAND OF RAIN/TSRA EWD. NO OTHER CHANGES TO ONGOING FORECAST FOR THIS UPDATE AND WEB/TEXT DATA HAS BEEN ALREADY SENT. PREVIOUS DISCUSSION FOLLOWS...WILL MAINTAIN MENTION OF ISOLATED STRONG IN THE HWO TODAY BUT CHANCE FOR STRONG CONVECTION WILL DECREASE TOMORROW DUE TO MID LEVEL CLOUD COVER AND SLIGHTLY COOLER LOW LEVEL TEMPS. THE AIR MASS WILL BE DRIER OVER ERN ZONES... ESPECIALLY THURSDAY WHEN LOWER DEWPOINTS ARE ADVECTED IN AT LOWER LEVELS FROM THE EAST. AGREE WITH MOS TEMPERATURE TREND FOR SLIGHTLY COOLER HIGHS TOMORROW WHEN 925/850 TEMPS FALL A LITTLE AS THE UPPER TROUGH PIVOTS THROUGH./07/ LONG TERM...FRIDAY THROUGH WEDNESDAY...WEAK U/L TROUGHING WILL CONTINUE OVER THE AREA FRIDAY WITH THE SURFACE RIDGE EXTENDING WEST OVER THE AREA FROM THE EAST COAST. THE LATEST GFS RUN DEVELOPS A LOW OVER OKLAHOMA LATE FRIDAY INTO SATURDAY AND PUSHES IT UP INTO THE OHIO VALLEY WITH A COLD FRONT EXTENDING ACROSS ARKANSAS. THE GFS NOR THE EURO ARE NOT AS DEEP WITH THE U/L TROUGH OVER THE WEEKEND...BUT DOES SLOWLY PUSH THE COLD FRONT INTO THE NORTH MISSISSIPPI SATURDAY NIGHT. THE GFS...ENSEMBLES AND THE EURO QUICKLY BUILDS UPPER RIDGING OVER THE AREA ON SUNDAY AND THE FRONT STALLS OUT AND WEAKENS OVER THE CWA. THE BEST CHANCE FOR CONVECTION LOOKS LIKE IT WILL BE IN THE WESTERN PORTIONS OF THE AREA WITH DRYER AIR IN THE EAST. STRONG U/L RIDGING CONTINUES TO BUILD IN ON MONDAY AND CONTINUES THROUGH MID WEEK...BUT THE GFS DOES INDICATE A DRYER NORTHEAST FLOW ON MONDAY AND TUESDAY OVER THE AREA WITH MORE ISOLATED AFTERNOON THUNDERSTORM ACTIVITY. GUIDANCE POPS AND TEMPS LOOK PRETTY GOOD THROUGH THE PERIOD...SO DID NOT MAKE ANY MAJOR ADJUSTMENTS./15/ && .AVIATION...VFR SHOULD PREVAIL THROUGH 20Z MOST LOCATIONS BEFORE ISOLATED SHRA/TSRA WILL BEGIN TO DEVELOP...SHRA/TSRA INCREASING OVER THE AREA FROM W TO E DURING THE AFTERNOON. STRONGER THUNDERSTORMS WILL OCCASIONALLY LOWER CIGS/VSBYS TO IFR/MVFR LEVELS MAINLY W OF I-55. TSRA WILL BE MORE ISOLATED IN NATURE EAST OF HIGHWAY 49 THIS AFTERNOON DUE TO LESS HUMID CONDITIONS OVER THAT AREA. CONVECTION SHOULD PERSIST THROUGH THE EVENING IN WRN PORTIONS BUT SHOULD DIMINISH AFTER 06Z WITH MINIMAL SHRA PERSISTING LATE TONIGHT N OF I-20./40/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 90 71 88 69 / 37 48 46 25 MERIDIAN 93 67 88 68 / 15 39 27 16 VICKSBURG 90 72 89 70 / 60 51 52 28 HATTIESBURG 93 72 91 69 / 22 29 36 21 NATCHEZ 89 72 89 71 / 58 41 55 23 GREENVILLE 89 71 88 70 / 80 68 64 27 GREENWOOD 90 71 88 69 / 49 60 58 24 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 630 AM CDT WED SEP 5 2007 .AVIATION... IFR/MVFR CIGS HAVE RETURNED ALONG WITH SOME LIGHT FOG OF 4 TO 5 MILES THIS MORNING ACROSS WEST CENTRAL TEXAS. LOOKING FOR MOST STATIONS TO LIFT FROM IFR TO LIFT TO MVFR 15-16Z...BUT MAY TAKE LONGER FURTHER SOUTH AT KSOA AND KJCT WHERE MID/UPPER LEVEL CLOUDS ARE MORE EXTENSIVE AND WHERE LIGHT SHOWERS WERE MOVING EAST. MVFR CIGS SHOULD LIFT AROUND 18Z. WILL LIKELY SEE MVFR CIG RETURN TO I-10 CORRIDOR...KJCT AND KSOA TAFS LATE TONIGHT. && .PREV DISCUSSION... /ISSUED 327 AM CDT WED SEP 5 2007/ SHORT TERM... UPPER LOW THAT WAS OVER WEST TEXAS LAST NIGHT HAS MOVED INTO WESTERN OKLAHOMA THIS MORNING. A SMALL JET STREAK IS MOVING EAST ACROSS WEST TEXAS FROM THE DAVIS MOUNTAINS INTO THE NORTHERN EDWARDS PLATEAU...AS SEEN BY ENHANCED UPPER LEVEL CLOUDS IN WV/IR IMAGERY. RUC80 ANALYZES THIS FEATURE AS WELL...AND SHOWER/THUNDERSTORM ACTIVITY CONTINUES TO DEVELOP ON THE NOSE OF THIS FEATURE JUST EAST OF OUR AREA. THESE STORMS SHOULD CONTINUE TO PUSH EAST AWAY FROM OUR AREA THROUGH THE REST OF THE MORNING. WITH THIS IN MIND...HAVE GONE AHEAD AND CANCELED THE FLASH FLOOD WATCH FOR THE REST OF THE MORNING SINCE THE HEAVY RAIN THREAT IS EAST OF OUR CWA. THE JEST STREAK MAY RESULT IN SOME SHOWERS OVER THE SOUTHERN HALF OF OUR CWA THIS MORNING...SO WILL KEEP A CHANCE OF SHRA/TSRA THERE TODAY...MAINLY FOR THE MORNING HOURS. MID/UPPER LEVEL CLOUDS WILL BE AROUND AGAIN TODAY AS MOISTURE STREAMS TO THE EAST/NORTHEAST FROM HENRIETTE. WE ALSO HAVE LOW CLOUDS DEVELOPING UNDER CLEAR SKIES OVER OUR NORTHERN CWA...AND EXPECT THESE TO ERODE THROUGH THE MORNING HOURS. SAW TEMPERATURES REACH 80 OR WARMER IN AREAS THAT DIDN/T SEE RAIN YESTERDAY...AND HAVE KEPT THE WARMING TREND FOR TODAY AS LESS RAIN IS EXPECTED TODAY. CONTINUE TO TREND POPS DOWNWARD TONIGHT...KEEPING ONLY SLIGHT CHANCE POPS IN FOR SOUTHERN AND EASTERN AREAS. WITH MOISTURE CONTINUING TO STREAM NORTHWARD AT LOW LEVELS...AND MOISTURE ALOFT FROM HENRIETTE...CANNOT RULE OUT SOME SHOWERS FOR SOUTHERN AREAS. LONG TERM... HENRIETTE IS EXPECTED TO CONTINUE ON A NORTHWARD TRACK INTO WESTERN NEW MEXICO BY TOMORROW. HOWEVER...THERE IS ENOUGH UNCERTAINTY ABOUT THE EXACT POSITION OF THE STORM TO KEEP SLIGHT CHANCE POPS GOING FOR WESTERN AREAS OF THE CWA. MOST OF THE RELATED ACTIVITY FROM HENRIETTE IS EXPECTED TO BE WEST AND NORTH OF OUR CWA...BUT THE BIG COUNTRY...ALONG AND NORTH OF INTERSTATE 20 COULD SEE SOME PRECIPITATION THURSDAY INTO FRIDAY AS THE STORM IS ABSORBED INTO THE MEAN WESTERLY FLOW...THEN ACCELERATES TO THE NORTHEAST ACROSS WESTERN OKLAHOMA AND SOUTHERN KANSAS THURSDAY NIGHT. HENRIETTE IS EXPECTED TO BE PICKED UP AND PULLED NORTHWARD BY AN UPPER LOW THAT WILL BE EJECTING TO THE EAST OUT OF THE INTERMOUNTAIN WEST THURSDAY/THURSDAY NIGHT. GFS CONTINUES TO SHOW A WEAK COLD FRONT/WIND SHIFT PUSHING INTO THE BIG COUNTRY BEHIND THIS LOW FRIDAY INTO SATURDAY. SO HAVE KEPT LOW ORDER CHANCE AND SLIGHT CHANCE POPS GOING FOR THE AREA THROUGH THE WEEKEND ALONG THE POSSIBLE STAGNANT BOUNDARY. AS THE BOUNDARY LIFTS BACK TO THE NORTH LATE IN THE WEEKEND AND EARLY NEXT WEEK...WE COULD CONTINUE TO SEE A CHANCE FOR SHOWERS AND THUNDERSTORMS...SO WILL KEEP THE LOW ORDER POPS IN THROUGH SUNDAY NIGHT. AFTER THAT HAVE TAKEN RAIN CHANCES OUT AS THE RIDGE BECOMES BETTER ESTABLISHED OVER THE SOUTHERN PLAINS. HAVE NOT MADE MANY CHANGES TO TEMPERATURES IN THE EXTENDED FORECAST WITH NEAR NORMAL READINGS EXPECTED. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 86 70 88 73 / 20 10 20 20 SAN ANGELO 89 72 89 72 / 20 10 10 10 JUNCTION 86 72 88 74 / 40 20 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 99/99/04 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 351 PM EDT WED SEP 5 2007 .DISCUSSION...THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR RAIN AND THUNDERSTORMS THURSDAY AFTERNOON AND THURSDAY NIGHT. .SYNOPSIS...WATER VAPOR IMAGERY AND RUC SHOWING A NUMBER OF WEAK SHORTWAVES CAUGHT IN A ZONAL FLOW ACROSS SOUTHERN CANADA. A CLOSED LOW IS OVER SOUTHERN IDAHO. SURFACE ANALYSIS DEPICTS A LOW OVER WESTERN HUDSON BAY...WITH A WARM FRONT EXTENDING ACROSS EASTERN ONTARIO INTO THE EASTERN OHIO RIVER VALLEY...AND A COLD FRONT DRAPED TO THE SOUTHWEST THROUGH WESTERN ONTARIO INTO CENTRAL SOUTH DAKOTA. WARM AIR ADVECTION PUSHED THE TEMPERATURES UP TO AROUND 90 TODAY ACROSS THE FORECAST AREA. THIS GENERATED A CUMULUS CLOUDS. A CAP AROUND 750MB AND DRY CONDITIONS BELOW 850MB KEEP ANY OF THIS FROM TURNING INTO SHOWERS OR THUNDERSTORMS. .SHORT TERM (TONIGHT AND THURSDAY)... WILL CONTINUE TO BE MONITORING THE PROGRESSION OF AN APPROACHING LOW AND ITS ASSOCIATED FRONTAL BOUNDARIES...AS THEY MAKE THEIR WAY TOWARDS UPPER MICHIGAN THURSDAY NIGHT AND FRIDAY. CURRENTLY THIS SYSTEM IS GAINING STEAM OVER THE DAKOTAS DOWN THROUGH EASTERN COLORADO. WARM AIR HAS BEEN ABLE TO SURGE NORTHWARD ACROSS UPPER MICHIGAN TODAY...WITH READINGS IN THE MID TO UPPER 80S BEING COMMON. WE WILL REMAIN IN THE WARM SECTOR UNTIL THE PASSAGE OF THE COLD FRONT ON FRIDAY. SO...AFTER A WARM DAY...A WARM OVERNIGHT CAN BE EXPECTED. FEW CHANGES WERE NEEDED TO THE ONGOING FORECAST TEMPERATURE WISE...WITH OVERNIGHT LOWS 65 TO 70. PLACED PATCHY FOG IN THE FORECAST FOR LATE OVERNIGHT TONIGHT. HOWEVER...WITH TEMPERATURES REMAINING IN THE MID TO UPPER 60S AND DEW POINTS HOVERING A 3-4 DEGREES BELOW THESE LEVELS...BELIEVE THAT FOG WILL BE MUCH MORE LIMITED THAN THE PREVIOUS 2 NIGHTS/MORNINGS. EXPECT SHOWERS AND THUNDERSTORMS TO SLIDE IN FROM THE WEST AND SOUTH MAINLY TOMORROW AFTERNOON...WITH ONLY LIGHT PRECIPITATION AMOUNTS FIGURED UNTIL THE ACTUAL FRONTAL PASSAGE. EXTENDED...THURSDAY NIGHT THROUGH WEDNESDAY THE SHORTWAVE WILL SHIFT THROUGH THE BASE OF THE LONG WAVE TROUGH AND THROUGH THE FORECAST AREA LATE THURSDAY NIGHT AND FRIDAY. THE SURFACE LOW WILL LIFT OUT OF THE CENTRAL PLAINS INTO THE WESTERN LAKE SUPERIOR BY 12Z FRIDAY AND INTO EAST CENTRAL ONTARIO ON FRIDAY DRAGGING THE COLD FRONT THROUGH THE FORECAST AREA. DEEP LOW LEVEL MOISTURE WILL ACCOMPANY THIS INSTABILITY. THUS LOOKING FOR A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS THURSDAY NIGHT AND BETTER CHANCE ON FRIDAY. DRY AIR WILL ADVECT INTO THE AREA BEHIND THIS ACTIVITY ON FRIDAY NIGHT AND SATURDAY ON THE LEADING EDGE OF A RIDGE AND FOLLOWING THE FRONT. THUS LOOKING FOR THE SHOWERS AND THUNDERSTORMS TO END. MODELS CONTINUE TO SHOW CONSIDERABLE AMOUNT OF INCONSISTANCE. HPC FAVORS THE ECMWF BUT THAT SOLUTION STILL HAS SOME RUN TO RUN INCONSISTENCY AS WELL. THE LOCALLY RUN HEMI WRF IS CLOSE TO THE 05/00Z ECMWF RUN AND IS CONSISTENT THROUGH OUT THE RUN SO WILL FAVOR THAT. THE LONG WAVE TROUGH REMAINS OVER CENTRAL CANADA. WEAK SHORTWAVE OVER NORTHERN MINNESOTA WILL PROGRESS THROUGH THIS TROUGH AND MOVE INTO THE LAKE SUPERIOR ON SUNDAY WHILE THE SURFACE HIGH OVER MANITOBA SHIFTS INTO NORTHERN ONTARIO. THE UPPER LEVEL JET MAX WILL SHIFT INTO EAST CENTRAL ONTARIO PUTTING THE FORECAST AREA UNDER THE RIGHT EXIT REGION OF THE JET MAX OVER THE NORTHWEST MINNESOTA. A WEAK SURFACE TROUGH WILL DEVELOP OVER MINNESOTA SUNDAY MORNING AND MOVE INTO WEST U.P. AVAILABLE MOISTURE APPEARS TO BE MARGINAL FOR CHANCE OF RAIN. WILL KEEP JUST A MENTION OF SHOWERS IN THE FORECAST. THE LONG WAVES TROUGH WILL DIG INTO THE NORTHERN PLAINS SUNDAY NIGHT AND MONDAY. AN AREA OF 850-500MB Q-VECTOR CONVERGENCE SWEEPING THROUGH THIS TROUGH WILL MOVE THROUGH THE U.P. SUNDAY NIGHT. THE SURFACE LOW WILL SHIFT OUT THE CENTRAL PLAINS THROUGH THE U.P. ON MONDAY. 320K ISENTROPIC ANALYSIS SHOWS THAT ASCENT WILL BE STRONGEST IN THE EARLY MORNING...AND NEGLIBLE DURING THE DAY. THE UPPER LEVEL JET MAX WILL RACE ACROSS THE FORECAST AREA ON MONDAY. LOW LEVEL MOISTURE WILL BE LIMITED DURING THE DAY. SO WILL GO ALONG WITH HPC AT THIS AND KEEP IT DRY DURING THE DAY. THE LONG WAVE TROUGH WILL GRADUALLY DEEPEN AND MOVE THROUGH THE FORECAST AREA MONDAY NIGHT THROUGH TUESDAY NIGHT...THUS WILL FAVOR HPC GUIDANCE AND KEEP SHOWERS AND THUNDERSTORMS OVER THE AREA THROUGH THAT PERIOD. GUIIDANCE ALSO FAVOR DRY AIR ADVECTION INTO THE AREA ON WEDNESDAY ENDING THE PRECIPITATION. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... A COLD FRONT APPROACHING FROM THE DAKOTAS COMBINED WITH THE SETTING OF THE SUN WILL ALLOW FOR A LOW LEVEL JET TO DEVELOP ACROSS UPPER MICHIGAN AFTER 00Z. THUS...LLWS IS INCLUDED FOR BOTH TAF SITES THROUGH 12Z WHEN SURFACE WIND GUSTS SHOULD BE COMING UP. OTHERWISE...GOOD CEIGS AND VIS ARE EXPECTED THOUGH THE NEXT 24 HOURS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... INCREASED WINDS ANTICIPATED OVER THE NEXT FEW DAYS...AS A FRONTAL BOUNDARY OVER EASTERN PORTIONS OF NORTH DAKOTA THIS AFTERNOON NEARS LAKE SUPERIOR. FOR TONIGHT...AHEAD OF THIS FRONT...WINDS MAY GUST UP TO 30 KT. THESE GUSTS SHOULD THEN DIMINISH THURSDAY...BEFORE INCREASING TO AROUND 25KT AS THE FRONT TRACKS OVER NORTHERN AND WESTERN LAKE SUPERIOR THURSDAY NIGHT. THE SURFACE LOW ITSELF SHOULD BE OVER WESTERN LAKE SUPERIOR BY DAWN FRIDAY. THE ACTUAL COLD FRONT SHOULD CROSS OVER DURING THE DAY FRIDAY...WITH NW WINDS OF 30KT POSSIBLE BEHIND IT. WINDS WILL THEN DECREASE LATE FRIDAY NIGHT AND REMAIN AT OR BELOW 20KT THROUGH THE REMAINDER OF THE PERIOD. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...KF EXTENDED...DLG AVIATION/MARINE...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN ANGELO TX 1238 PM CDT WED SEP 5 2007 .AVIATION... AREAS OF MVFR CIGS BKN020-030 ARE EXPECTED ACROSS WEST CENTRAL TEXAS UNTIL 05/21Z. MAINLY VFR CONDITIONS ARE EXPECTED BETWEEN 05/21Z AND 06/07Z. IFR CIGS BLO OVC010 WILL DEVELOP ACROSS THE SOUTHERN 2/3 OF WEST CENTRAL TEXAS AFTER 06/07Z...WITH MVFR CIGS BKN010-020 ACROSS THE BIG COUNTRY. WINDS WILL BE SOUTH TO SOUTHEAST AT 5 TO 10 KNOTS. 21 && PREV DISCUSSION... /ISSUED 327 AM CDT WED SEP 5 2007/ SHORT TERM... UPPER LOW THAT WAS OVER WEST TEXAS LAST NIGHT HAS MOVED INTO WESTERN OKLAHOMA THIS MORNING. A SMALL JET STREAK IS MOVING EAST ACROSS WEST TEXAS FROM THE DAVIS MOUNTAINS INTO THE NORTHERN EDWARDS PLATEAU...AS SEEN BY ENHANCED UPPER LEVEL CLOUDS IN WV/IR IMAGERY. RUC80 ANALYZES THIS FEATURE AS WELL...AND SHOWER/THUNDERSTORM ACTIVITY CONTINUES TO DEVELOP ON THE NOSE OF THIS FEATURE JUST EAST OF OUR AREA. THESE STORMS SHOULD CONTINUE TO PUSH EAST AWAY FROM OUR AREA THROUGH THE REST OF THE MORNING. WITH THIS IN MIND...HAVE GONE AHEAD AND CANCELED THE FLASH FLOOD WATCH FOR THE REST OF THE MORNING SINCE THE HEAVY RAIN THREAT IS EAST OF OUR CWA. THE JEST STREAK MAY RESULT IN SOME SHOWERS OVER THE SOUTHERN HALF OF OUR CWA THIS MORNING...SO WILL KEEP A CHANCE OF SHRA/TSRA THERE TODAY...MAINLY FOR THE MORNING HOURS. MID/UPPER LEVEL CLOUDS WILL BE AROUND AGAIN TODAY AS MOISTURE STREAMS TO THE EAST/NORTHEAST FROM HENRIETTE. WE ALSO HAVE LOW CLOUDS DEVELOPING UNDER CLEAR SKIES OVER OUR NORTHERN CWA...AND EXPECT THESE TO ERODE THROUGH THE MORNING HOURS. SAW TEMPERATURES REACH 80 OR WARMER IN AREAS THAT DIDN/T SEE RAIN YESTERDAY...AND HAVE KEPT THE WARMING TREND FOR TODAY AS LESS RAIN IS EXPECTED TODAY. CONTINUE TO TREND POPS DOWNWARD TONIGHT...KEEPING ONLY SLIGHT CHANCE POPS IN FOR SOUTHERN AND EASTERN AREAS. WITH MOISTURE CONTINUING TO STREAM NORTHWARD AT LOW LEVELS...AND MOISTURE ALOFT FROM HENRIETTE...CANNOT RULE OUT SOME SHOWERS FOR SOUTHERN AREAS. LONG TERM... HENRIETTE IS EXPECTED TO CONTINUE ON A NORTHWARD TRACK INTO WESTERN NEW MEXICO BY TOMORROW. HOWEVER...THERE IS ENOUGH UNCERTAINTY ABOUT THE EXACT POSITION OF THE STORM TO KEEP SLIGHT CHANCE POPS GOING FOR WESTERN AREAS OF THE CWA. MOST OF THE RELATED ACTIVITY FROM HENRIETTE IS EXPECTED TO BE WEST AND NORTH OF OUR CWA...BUT THE BIG COUNTRY...ALONG AND NORTH OF INTERSTATE 20 COULD SEE SOME PRECIPITATION THURSDAY INTO FRIDAY AS THE STORM IS ABSORBED INTO THE MEAN WESTERLY FLOW...THEN ACCELERATES TO THE NORTHEAST ACROSS WESTERN OKLAHOMA AND SOUTHERN KANSAS THURSDAY NIGHT. HENRIETTE IS EXPECTED TO BE PICKED UP AND PULLED NORTHWARD BY AN UPPER LOW THAT WILL BE EJECTING TO THE EAST OUT OF THE INTERMOUNTAIN WEST THURSDAY/THURSDAY NIGHT. GFS CONTINUES TO SHOW A WEAK COLD FRONT/WIND SHIFT PUSHING INTO THE BIG COUNTRY BEHIND THIS LOW FRIDAY INTO SATURDAY. SO HAVE KEPT LOW ORDER CHANCE AND SLIGHT CHANCE POPS GOING FOR THE AREA THROUGH THE WEEKEND ALONG THE POSSIBLE STAGNANT BOUNDARY. AS THE BOUNDARY LIFTS BACK TO THE NORTH LATE IN THE WEEKEND AND EARLY NEXT WEEK...WE COULD CONTINUE TO SEE A CHANCE FOR SHOWERS AND THUNDERSTORMS...SO WILL KEEP THE LOW ORDER POPS IN THROUGH SUNDAY NIGHT. AFTER THAT HAVE TAKEN RAIN CHANCES OUT AS THE RIDGE BECOMES BETTER ESTABLISHED OVER THE SOUTHERN PLAINS. HAVE NOT MADE MANY CHANGES TO TEMPERATURES IN THE EXTENDED FORECAST WITH NEAR NORMAL READINGS EXPECTED. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 86 73 88 74 / 20 10 20 20 SAN ANGELO 89 73 90 75 / 20 10 10 10 JUNCTION 86 75 88 75 / 40 20 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ tx