AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 300 PM EDT MON OCT 01 2007 .SYNOPSIS...18Z WATER VAPOR AND H4 RUC ANALYSIS STILL SHOWING A VERY ACTIVE NORTHERN STREAM WITH A SHARP TROUGH ASHORE ACROSS THE PACIFIC NORTHWEST FROM BRITISH COLUMBIA TO NORTHERN CALIFORNIA...RIDGING FURTHER DOWNSTREAM ACROSS THE PLAINS...ANOTHER POTENT SHORTWAVE CLOSING OFF ACROSS THE GREAT LAKE STATES AND ANOTHER RIDGE UP THE EAST COAST TO NEW ENGLAND. CLOSER TO HOME WATCHING AN UPPER LOW MOVING WEST OUT OF THE FLORIDA STRAITS. THIS SYSTEM IS HAVING LITTLE IMPACT ON OUR FORECAST AREA THIS AFTERNOON. AT THE SURFACE...TIGHT GRADIENT CONTINUES OVER THE REGION BETWEEN STRONG HIGH PRESSURE TO THE NORTH AND A SURFACE TROUGH NEAR THE SOUTHERN FL PENINSULA. ATLANTIC MOISTURE CONTINUES TO ADVECT ASHORE ALONG THE EAST COAST OF THE PENINSULA. REGIONAL RADAR SHOWING SCT SHOWERS/SPRINKLES MOVING ASHORE FROM JACKSONVILLE SOUTHWARD TO DAYTONA BEACH AND MELBOURNE. RADAR HAS SHOWN A SLOW DECREASE IN THE SHOWER COVERAGE INTO THE EARLY AFTERNOON AND REALLY DO NOT EXPECT ANYTHING MORE THAN A SPRINKLE OR TWO INTO THE SOUTHEAST BIG BEND FOR THE REST OF THE DAY. DEBATED DROPPING THE SLIGHT CHANCE POP OVER THIS AREA...HOWEVER SINCE THE WX GRIDS ARE ONLY CARRYING SPRINKLES...WILL LEAVE MENTION IN DESPITE THE VERY MINIMAL IMPACT. CLOUDS HAVE BEEN FAIRLY STUBBORN SOUTH AND EAST OF A KTLH TO KVLD LINE...WITH MOSTLY SUNNY TO SUNNY SKIES FURTHER NORTH AND WEST. && .SHORT TERM (TONIGHT THROUGH WEDNESDAY NIGHT)... MAIN ISSUE WITH THE SHORT TERM FORECAST WILL BE THE EVOLUTION OF THE UPPER LOW EXITING THE FLORIDA STRAITS INTO THE SOUTHEASTERN GULF OF MEXICO AND SOME POSSIBLE SURFACE LOW DEVELOPMENT ASSOCIATED WITH IT. ALL GUIDANCE MODELS ARE SHOWING THE CLOSED UPPER LOW EJECTING INTO THE EASTERN GULF OF MEXICO OVERNIGHT TONIGHT WITH AN UPPER TROUGH CONTINUING TO THE NORTHEAST OVER THE CENTRAL AND NORTHERN FLORIDA PENINSULA. BETTER MID/UPPER LEVEL MOISTURE WILL APPROACH THE FORECAST AREA FROM THE SOUTHEAST DURING THE NIGHT BUT APPEARS THAT THE PROGRESS WILL BE SLOW ENOUGH TO KEEP MOST OF THE AREA DRY INTO TUESDAY MORNING. ONLY EXCEPTION WILL BE THE FAR SOUTHEAST BIG BEND WHERE A CONTINUATION OF A FEW SPRINKLES/SHOWERS FROM THE NORTHEAST WILL BE POSSIBLE. LOW TEMPERATURES TONIGHT WILL BE COOLEST TO THE NORTH AND WEST WHERE UPPER 50S TO NEAR 60 WILL BE COMMON UNDER THE MOSTLY CLEAR SKIES. LOW WILL REMAIN IN THE MIDDLE AND UPPER 60S FOR THE SOUTHEAST THIRD OF THE AREA WHERE BETTER ATLANTIC MOISTURE AND MORE CLOUD COVER WILL BE PRESENT. SURFACE LOW PRESSURE IS EXPECTED TO DEVELOP UNDER THE UPPER LOW OFF THE SOUTHWEST FLORIDA COAST BY SUNRISE TUESDAY...BUT GUIDANCE IS NOT IN AGREEMENT AS TO DEGREE OF STRENGTHENING. GFS/ECMWF CONTINUE TO BE VERY CLOSE WITH THE NAM BEING THE STRONGER OUTLIER SOLUTION. THE NAM HAS A HISTORY OF OVER-DEVELOPING THESE SYSTEM AND SO DECIDED TO USE A SIMILAR FORECAST PHILOSOPHY AS LAST NIGHTS SHIFT AND GO WITH A GFS/ECMWF BLEND. THE NATIONAL HURRICANE CENTER IS WATCHING THIS LOW FOR SOME POSSIBLE SUB-TROPICAL DEVELOPMENT OVER THE NEXT SEVERAL DAYS...HOWEVER LOOKING AT THE LARGE AMOUNT OF DRY AIR NOW COVERING THE GOMEX IN THE MIDDLE AND UPPER LEVELS...IT WILL TAKE QUITE SOME TIME TO GET A SUBSTANTIAL SYSTEM GOING...IF AT ALL. WITH ALL THIS IN MIND...WILL ADVANCE THE POPS A BIT FURTHER TO THE NORTHWEST DURING TUESDAY WITH SLIGHT CHANCE GENERALLY SOUTH AND EAST OF A LINE FROM KPFN TO KTLH TO KVLD...AND BRING CHANCE 30-40 POPS UP INTO THE SOUTHEASTERN BIG BEND. BRINGING SLIGHT CHANCE POPS THIS FAR NORTH...MAY EVEN BE A BIT OPTIMISTIC FOR RAIN AS BEST DEEP LAYER (700-300MB Q-VECTOR FORCING REMAINS JUST TO OUR SOUTH). HIGH TEMPS GENERALLY IN THE MIDDLE AND UPPER 80S ONCE AGAIN. KEPT THINGS A FEW DEGREES COOLER FOR TAYLOR...DIXIE AND LAFAYETTE COUNTIES WITH LOWER TO MIDDLE 80S UNDER MORE PERSISTENT CLOUD-COVER AND BETTER SHOWER CHANCES. AS THE SURFACE AND UPPER LEVEL LOW PROGRESS WESTWARD ACROSS THE NORTH-CENTRAL GOMEX THROUGH THE REMAINDER OF THE SHORT TERM...WILL KEEP A GENERAL LOW END CHANCE POP ACROSS THE AREA WITH THE BEST DYNAMICS AND MOISTURE FOR SHOWERS ACROSS COASTAL AREAS. TIMING OF THE BEST RAIN CHANCES DURING THIS PERIOD IS NOT OF THE HIGHEST CONFIDENCE. MUCH WILL DEPEND ON JUST HOW MUCH SPIN-UP WE SEE OF THE SURFACE LOW AND ALSO ANY SMALLER SCALE IMPULSES ROTATING AROUND THE UPPER LOW. BASICALLY A SHOWER OR THUNDERSTORM WILL BE POSSIBLE AT ANY TIME...ALTHOUGH A SIGNIFICANT AMOUNTS OF QPF IN ANY ONE PLACE LOOKS UNLIKELY AND A WASHOUT DURING THE MID WEEK PERIOD IS NOT EXPECTED. DIURNAL TEMPERATURES WILL BE HELD IN CHECK WITH MORE ABUNDANT CLOUD COVER. GENERALLY LOOKING FOR MIDDLE 80S DURING THE DAY AND MIDDLE 60S TO LOWER 70S AT NIGHT. && .LONG TERM (THURSDAY THROUGH MONDAY)... THE 01/00Z EURO COMING IN NOW IS IN EXCELLENT AGREEMENT WITH THE 01/00Z GFS ON TAKING THE GULF LOW INTO THE WESTERN GULF TOWARD SOUTHERN TEXAS OR NORTHERN MEXICO. HOWEVER...PLENTY OF DEEP LAYER MOISTURE STAYS OVER OUR REGION IN THE WAKE OF THIS SYSTEM ALLOWING FOR CHANCES OF SHOWERS AND THUNDERSTORMS INTO THE FIRST PART OF THE WEEKEND. THE GFS IS BRINGING A FRONTAL SYSTEM INTO THE REGION LATE IN THE WEEKEND...HOWEVER THE 30/12Z EURO WAS MUCH SLOWER WITH THIS SYSTEM AND DIDN`T BRING THE COLD FRONT THROUGH THE REGION UNTIL NEXT WEEK. THE 01/00Z EURO IS ABOUT 12 TO 18 HOURS BEHIND THE GFS WITH THIS FRONT AND BRINGS IT THROUGH ON MONDAY. IT WOULDN`T ENTIRELY SURPRISE ME TO END UP SEEING A BLEND OF THE MORE PROGRESSIVE GFS AND SLOWER EURO PAN OUT. WILL SLOW THE FRONTAL PROGRESSION THROUGH THE CWA ABOUT 12 HOURS...WHICH IS TYPICALLY WHAT WE`VE SEEN WHEN FORECASTING LONG RANGE FRONTAL PASSAGES THIS TIME OF YEAR. GENERALLY ACCEPTED THE MEX GUIDANCE TEMPS AND POPS...BUT DID ADJUST TEMPS DOWN A DEGREE OR TWO BASED ON EXPECTED CLOUD COVER EARLY IN THE LONG TERM FORECAST. && .AVIATION... VFR CONDITIONS WITH CLOUDS MOVING SW OFF THE ATLANTIC YIELDING OCNL CIGS 7-8K WITH OCCASIONAL CIGS DOWN TO 4K FT WITH DRIZZLE OR SPRINKLES AT KVLD AND POSSIBLY AT KTLH. SUSTAINED NE WINDS TO 15 MPH WITH GUSTS UP TO 20 MPH WILL CONTINUE INTO SUNSET...THEN 5-10 MPH. VFR CONDS LOOK GOOD INTO TUES MORNING WITH MARGINAL MVFR CIGS POSSIBLE MNLY AT KVLD 08Z-13Z. THEN TUES DAYLIGHT CONDS WILL BE SIMILAR TO THIS AFTERNOON REGARDING CIGS AND WINDS. && .MARINE... TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE TO OUR NORTH AND A SURFACE TROUGH TO THE SOUTH WILL KEEP ELEVATED NORTHEAST FLOW GOING ACROSS ALL MARINE LEGS INTO TUESDAY MORNING. SMALL CRAFT ADVISORIES WILL REMAIN IN EFFECT FOR THE NEAR SHORE LEGS THROUGH TUESDAY MORNING AND ACROSS THE OFFSHORE LEGS THROUGH TUESDAY AFTERNOON. WILL BE WATCHING LOW PRESSURE MOVE TO THE SOUTH AND WEST OF THE FORECAST WATERS TUESDAY NIGHT THROUGH WEDNESDAY WITH THE PRESSURE GRADIENT RELAXING AND WINDS AND SEAS DROPPING BELOW ADVISORY LEVELS. FLOW ON THE EASTERN SIDE OF THIS LOW INTO THE LATER PART OF THE WORKWEEK WILL BE GENERALLY FROM THE SOUTHEAST AND UNDER CAUTIONARY LEVELS. && .FIRE WEATHER... LOOKS LIKE RH VALUES ARE GOING TO GET DOWN TO 35 PERCENT FOR AN HOUR OR TWO ACROSS PORTIONS OF THE EASTERN FLORIDA PANHANDLE LATE THIS AFTERNOON AND EARLY EVENING. WITH THE GUSTY NORTHWEST WIND AND HIGH DISPERSION INDICES...WE ONLY NEED ONE HOUR TO VERIFY A WARNING AND SO WILL ISSUE A SHORT FUSE RED FLAG WARNING FOR WALTON...JACKSON... HOLMES...WASHINGTON...AND CALHOUN COUNTIES UNTIL 600 PM CDT. INCREASING LOW LEVEL MOISTURE WILL THEN KEEP CONDITIONS WELL ABOVE CRITICAL LEVELS FOR ALL AREAS THROUGH THE MIDDLE PART OF THE WEEK. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 64 87 70 86 72 / 0 15 40 40 30 PANAMA CITY 66 88 72 87 74 / 0 15 40 40 30 DOTHAN 58 87 66 85 68 / 0 05 25 30 20 ALBANY 60 87 66 86 69 / 0 05 25 30 20 VALDOSTA 64 84 69 87 70 / 0 20 30 40 20 CROSS CITY 69 83 69 88 71 / 15 40 40 40 30 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...RED FLAG WARNING IN EFFECT UNTIL 23Z THIS EVENING FOR WALTON...JACKSON...HOLMES...WASHINGTON...AND CALHOUN COUNTIES. GMZ750/755/730...SMALL CRAFT ADVISORY UNTIL 15Z TUESDAY MORNING. GMZ770/775...SMALL CRAFT ADVISORY UNTIL 21Z TUESDAY AFTERNOON. && $$ PUBLIC/MARINE...MROCZKA LONG TERM...GODSEY AVIATION/FIRE WEATHER...BLOCK/MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 930 AM EDT MON OCT 01 2007 .SYNOPSIS/UPDATE... 13Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING A VERY ACTIVE NORTHERN STREAM ACROSS THE NORTHERN U.S. AND SOUTHERN CANADA. FEATURES OF NOTE INCLUDE A SHARP TROUGH COMING ASHORE FROM BRITISH COLUMBIA TO NORTHERN CALIFORNIA...RIDGING FURTHER DOWNSTREAM ACROSS THE PLAINS...ANOTHER POTENT SHORTWAVE TRAVERSING THE GREAT LAKE STATES FOLLOWED BY YET ANOTHER RIDGE UP THE EAST COAST TO NEW ENGLAND. CLOSER TO HOME WE STILL SEE UPPER RIDGING ALONG THE GULF COAST INCLUDING OUR FORECAST AREA. AN UPPER LOW IS SPINNING ACROSS THE FLORIDA STRAITS AND SO FAR IS HAVING LITTLE TO NO IMPACT FOR OUR WEATHER. AT THE SURFACE...TIGHT GRADIENT CONTINUES OVER THE REGION BETWEEN STRONG HIGH PRESSURE TO THE NORTH AND A SURFACE TROUGH APPROACHING THE SOUTHEAST COAST OF THE FL PENINSULA. THIS GRADIENT IS RESULTING IN A STEADY NORTHEAST FLOW. PLENTY OF ATLANTIC MOISTURE IS BEING ADVECTED ASHORE ALONG THE EAST COAST OF THE PENINSULA THIS MORNING AND THIS WILL CONTINUE THROUGH THE REST OF THE DAY. REGIONAL RADAR SHOWS SCT-NMRS SHOWERS/SPRINKLES MOVING ASHORE FROM JACKSONVILLE SOUTHWARD TO DAYTONA BEACH AND MELBOURNE. RADAR HAS SHOWN A FEW OF THESE SHOWERS MAKING THE TRIP ACROSS THE PENINSULA TO OUR SOUTHEAST BIG BEND ZONES. RADAR SAMPLING IS FAIRLY HIGH IN THIS AREA AND AM NOT CONVINCED THAT MOST IF NOT ALL OF THIS ACTIVITY IS REMAINING ALOFT. IF ANY OF THIS ACTIVITY IS REACHING THE SURFACE IT SHOULD BE VERY LIGHT AND AMOUNT TO ONLY A TRACE TO A FEW HUNDREDTHS OF AN INCH AT MOST. DID ADD A SLIGHT 15-20% POP WITH SPRINKLE WORDING TO THE FORECAST OVER TAYLOR...LAFAYETTE AND DIXIE COUNTIES THROUGH THE AFTERNOON TO ACCOUNT FOR THIS ACTIVITY...BUT THIS SHOULD NOT HAVE A SIGNIFICANT IMPACT EITHER WAY. SPRINKLES OR NOT...THE ATLANTIC MOISTURE IS RESULTING IN HIGHER CLOUDCOVER SOUTH AND EAST OF A LINE FROM TLH TO KVLD THIS MORNING AND THIS IS LIKELY TO PERSIST INTO THE AFTERNOON. WILL UPDATE THE GRIDS TO ACCOUNT FOR THIS TREND. WITH THE HIGHER CLOUD COVER AND ALSO SOME ADDITIONAL COOLING AS A RESULT OF EVAPORATING SHOWERS/SPRINKLES...WILL DROP HIGH TEMPS OVER THE EFFECTED REGION ANOTHER COUPLE OF DEGREES. OUTSIDE OF THE EASTERN BIG BEND AREA...FORECAST LOOKS ON TRACK WITH A PLEASANT DAY IN STORE. PARTLY SUNNY SKIES AND HIGHS IN THE MIDDLE AND UPPER 80S CAN BE EXPECTED. 12Z KTLH SOUNDING SHOWING VERY DRY AIRMASS ABOVE 750MB (DEWPOINT DEPRESSIONS OF 40-50C) AND A LOW PW AROUND 1.05". WITH A PROFILE LIKE THIS...THE DRY FORECAST LOOKS JUST FINE. EXPECT A BREEZY DAY INTO THE AFTERNOON WITH NORTHEAST WINDS BETWEEN 10 AND 15 MPH COMMON. && .AVIATION... VFR CONDITIONS WITH CIGS AROUND 4K AND 7-8K WILL LIKELY CONTINUE THROUGH TONIGHT...WITH OCCASIONAL BORDERLINE MVFR CIGS DOWN TO 3K FT MOVING WEST OFF THE ATLANTIC AND AFFECTING MAINLY KVLD AND KTLH. SUSTAINED NE WINDS 10 TO 15 MPH WITH GUSTS UP TO 20 MPH WILL CONTINUE INTO SUNSET. VFR CONDS LOOK GOOD INTO OVERNIGHT HOURS. && .MARINE... SMALL CRAFT CONDITIONS CONTINUE ACROSS THE FORECAST WATERS THIS MORNING AND WILL MAKE NO CHANGES TO THE ADVISORIES AT THIS TIME. WINDS HAVE BEEN RUNNING OUT OF THE NORTHEAST AROUND 20 KNOTS WITH GUSTS AROUND 25 KNOTS. SEAS AT THE BUOYS HAVE BEEN RUNNING BETWEEN 5 AND 7 FEET. && .FIRE WEATHER... WITH SOME MINOR CHANGES TO THE DEWPOINT GRIDS TO REPRESENT MORNING TRENDS AND LATEST GUIDANCE...STILL ONLY RECEIVING AN HOUR OR LESS OF RH AROUND 35 PERCENT FOR A VERY SMALL AREA OF THE EASTERN FLORIDA PANHANDLE ALONG AND TO THE NORTH OF I-10. WILL LEAVE WORDING JUST WORDING IN THE FWF FOR THE TIME BEING...BUT WILL KEEP A CLOSE EYE ON THE DIURNAL AFTERNOON DEWPOINT DECREASE. IF MIXING IS SLIGHTLY BETTER THAN EXPECTED THAN SOME FIRE WX CONCERNS MAY BE POSSIBLE FOR PLACES LIKE WALTON...JACKSON...AND HOLMES COUNTIES. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 86 64 89 68 86 / 0 0 10 10 30 PANAMA CITY 86 69 88 71 86 / 0 0 05 10 30 DOTHAN 87 59 89 64 89 / 0 0 0 05 20 ALBANY 86 61 89 64 88 / 0 0 0 05 20 VALDOSTA 84 65 88 67 87 / 10 05 10 20 30 CROSS CITY 84 69 86 69 87 / 20 10 30 30 30 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...SMALL CRAFT ADVISORY ALL LEGS. && $$ AVIATION...BLOCK REST OF DISCUSSION...MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 149 PM EDT SUN SEP 30 2007 .SYNOPSIS... STRONG HIGH PRESSURE WILL DOMINANT THE REGION THROUGH EARLY WEEK. A TROUGH OF LOW PRESSURE WILL DEVELOP OFF THE SOUTHEAST COAST MON AND THEN INTO THE GULF OF MEXICO FOR MID WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THIS MORNING STARTED OUT RATHER COOL WITH TEMPS DROPPING INTO THE 50S AWAY FROM THE COAST. MANY INLAND LOCATIONS DROPPED INTO THE LOWER 50S SO A FEW UPPER 40S LIKELY OCCURRED...MAINLY IN WIND SHELTERED AREAS. CLOSER TO THE COAST TEMPS RANGE FROM THE UPPER 50S TO THE MID-UPPER 60S ALONG THE IMMEDIATE BEACH FRONT. HIGH PRESSURE CENTERED ACROSS THE NE U.S. WILL HOLD FIRM ACROSS THE CAROLINAS AND GEORGIA TODAY AS THE UPPER RIDGE ACROSS THE LOWER-MID MISSISSIPPI VALLEY PROPAGATES SLOWLY EASTWARD. A DRY NE FLOW WILL KEEP TEMPS RATHER FALL LIKE WITH OBSERVED 1000-850MB THICKNESSES OFF THE 30/12Z RAOBS AT CHS/JAX SUPPORTING HIGHS IN THE UPPER 70S AND LOWER 80S. WILL LOWER TEMPS A DEG OR TWO ALONG THE LOWER SC COAST BUT TEMPS ELSEWHERE LOOK ON TARGET. DRY WX WILL PERSIST WITH CONSIDERABLE DRY AIR NOTED JUST OFF THE SURFACE. THE ONLY EXCEPTION MAY BE ALONG THE UPPER GA COAST WHERE LOW-LVL MOISTURE IS MORE PLENTIFUL. AN ISOLD SHOWER OR TWO CAN NOT BE COMPLETELY RULED OUT THERE WITH BETTER CHANGES MUCH FARTHER S... BUT PROBABILITIES LOOK TOO LOW TO JUSTIFY A MENTION ATTM. VISIBLE SATELLITE IMAGES SHOW AN EXTENSIVE STRATOCUMULUS FIELD OVER THE COASTAL WATERS WITH EVEN A FEW SHOWERS NOTED ALONG THE WESTERN WALL OF THE GULF STREAM. THE BULK OF THIS CLOUD COVER WILL REMAIN OFFSHORE BUT SOME IT WILL LIKELY BRUSH THE COAST THROUGH THE AFTERNOON...PARTICULARLY N COASTAL GA. THERE IS ALSO SOME INDICATION THAT A SHALLOW CUMULUS FIELD WILL FORM S OF THE I-16 CORRIDOR. SUNNY TO MOSTLY SUNNY SKIES WILL PREVAIL INLAND WITH PARTLY CLOUDY SKIES AT THE COAST. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/... HIGH PRESSURE TO OUR N WILL SLIP OFF THE COAST TONIGHT INTO MON WHILE SLOWLY LOSING IT/S GRIP OVER US. THE E/NE FLOW MAY BRING A FEW SHOWERS TO COASTAL GA BUT OTHERWISE DRY WX IS EXPECTED TO CONTINUE. LOWS WILL DROP INTO THE MID/UPPER 50S TONIGHT INLAND WITH MID/UPPER 60S NEAR THE COAST. HIGHS MON WILL REBOUND SLIGHTLY WITH MORE OF AN ONSHORE FLOW EXPECTED...ALTHOUGH THIS WILL ALSO YIELD A FEW MORE CLOUDS. IT WILL CONTINUE TO BE BREEZY...ESPECIALLY ALONG THE COAST. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... NOT MUCH CHANGE TO THE EXTENDED FORECAST. STILL APPEARS AS THOUGH AN AREA OF LOW PRESSURE WILL DEVELOP OFF THE SE U.S. COAST MON AND THEN SHIFT W INTO THE GULF OF MEX FOR MID WEEK. HIGH PRESSURE BUILDING IN N OF THIS SYSTEM LOOKS TO KEEP THINGS MAINLY DRY OVER OUR AREA. HOWEVER...DID NOT FEEL COMFORTABLE REMOVING POPS COMPLETELY AT THIS POINT. AS LONG AS THE WARMER AND DRIER PATTERN PANS OUT...TEMPS SHOULD GENERALLY BE ABOVE NORMAL THROUGH THE PERIOD. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. MAINLY NORTH TO NORTHEAST WINDS OF 10 TO 15 KNOTS AND INCREASING AFTER SUNRISE. THIS IS DUE TO THE PINCHING GRADIENT BETWEEN THE HIGH SLOWLY MOVING OFFSHORE AND THE LOW PRESSURE SYSTEM PUSHING NORTHWEST JUST SOUTH OF THE AREA. EXTENDED AVIATION OUTLOOK...VFR CONDITIONS WILL GENERALLY PREVAIL THROUGH THE MIDDLE OF THE WEEK. && .MARINE... NO CHANGES ARE PLANNED FOR THE GOING FORECAST. SOLID SMALL CRAFT ADVISORY CONDITIONS ARE IN PROGRESS ACROSS THE ENTIRE MARINE AREA THIS MORNING WITH WINDS NE 25 KT AND SEAS 5-8 FT NEAR SHORE AND 8-11 FT BEYOND 20 NM. THE SAVANNAH PILOT BOAT RECENTLY REPORTED NE WINDS OF 25-30 KT AND SEAS OF 6-8 FT 10 MILES E OF THE SAVANNAH RIVER ENTRANCE. THE CHARLESTON HARBOR PILOT BOAT REPORTED NE WINDS 20-25 KT WITH SEAS OF 6 FT 8 MILES E OF THE HARBOR ENTRANCE. WE ARE STILL MONITORING FOR A POSSIBLE UPGRADE TO A GALE WARNING FOR OUR GA WATERS WITH THE AFTERNOON FORECAST PACKAGE. A TIGHT SURFACE PRESSURE GRADIENT...LOW-LEVEL JETTING AND GOOD MIXING PROFILES...ESPECIALLY AT NIGHT...WILL KEEP STRONG NORTHEAST WINDS IN PLACE ACROSS THE COASTAL WATERS THROUGH MONDAY. AS A RESULT...A SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT FOR ALL COASTAL WATERS AND THE CHARLESTON HARBOR. THERE IS EVEN THE POSSIBILITY THAT AS LOW LEVEL WINDS INCREASE LATE TODAY INTO TONIGHT...FREQUENT GUSTS TO GALE FORCE MAY BE EXPERIENCED OVER THE OUTER GEORGIA WATERS...THEREFORE REQUIRING A GALE WARNING TO BE ISSUED AT A LATER TIME. THE LONG FETCH WILL ALLOW SWELLS TO CONTINUE TO BUILD...PEAKING OUT LATE MONDAY IN THE 7-9 FT RANGE IN THE SOUTH CAROLINA NEAR SHORE WATERS...8-10 FT RANGE IN THE GEORGIA NEAR SHORE WATERS AND 10-12 FT IN THE OUTER GEORGIA WATERS. HIGH PRESSURE WILL BEGIN TO WEAKEN OVER THE NORTHWEST ATLANTIC MONDAY NIGHT AND TUESDAY. A TROUGH OF LOW PRESSURE MAY APPROACH THE WATERS MID-WEEK...WITH HIGH PRESSURE THEN BUILDING BACK INTO THE AREA FROM THE NORTH BY THE END OF THE UPCOMING WORK WEEK. WINDS WILL BEGIN TO DIMINISH LATE MONDAY...AT WHICH TIME THE SMALL CRAFT ADVISORY FOR CHARLESTON HARBOR CAN BE DROPPED. THERE WILL BE SOME LAG FROM WHEN WINDS BEGIN TO DIMINISH TO WHEN SEAS FALL BELOW SMALL CRAFT ADVISORY CRITERIA...WHICH IS EXPECTED TO BE SOMETIME TUESDAY NIGHT FOR THE NEAR SHORE WATERS AND WEDNESDAY NIGHT FOR THE OUTER GEORGIA WATERS. LAKE WINDS...GOOD MIXING PROFILES AND 25-30 KT LOW LEVEL WINDS ARE LIKELY RESULTING IN STRONG NORTHEAST WINDS OVER LAKE MOULTRIE THIS MORNING. THE LATEST OBSERVATION FROM PINEVILLE SHOWED WINDS GUSTING OVER 20 MPH...WHICH IS PRETTY HIGH CONSIDERING PARCELS ARE ORIGINATING OVER LAND VERSUS THE WARMER LAKE WATERS. THE LATEST RUC SOUNDINGS WILL STILL SUPPORT AT LEAST 25 KT WIND GUSTS WITH HIGHER WINDS TONIGHT...SO THE LAKE WIND ADVISORY WILL BE EXTENDED THROUGH MONDAY MORNING. RIP CURRENTS...THE COMBINATION OF A STRONG NORTHEAST FLOW AND LONG PERIOD SWELLS IMPACTING THE SURF ZONE WILL RESULT IN A HIGH RISK OF RIP CURRENTS TODAY. THE RISK OF RIP CURRENTS WILL REMAIN ELEVATED INTO THE FIRST PART OF THE UPCOMING WEEK. && .TIDES/COASTAL FLOODING... THE COASTAL FLOOD WARNING AND COASTAL FLOOD ADVISORY HAVE EXPIRED. WE ARE CAREFULLY MONITORING TRENDS IN CASE ANOTHER ADVISORY IS NEEDED FOR THIS EVENING/S HIGH TIDE CYCLE. COASTAL FLOODING HAS BEEN REPORTED IN A NUMBER OF AREAS TODAY ALONG WITH MODERATE TO SEVERE BEACH EROSION. THE WORST EROSION AND HIGH SURF CONTINUES ACROSS N COASTAL GEORGIA WHERE SURF BREAKERS REMAIN IN THE 5-7 FT RANGE. PICTURES FROM THE TYBEE ISLAND AREA INDICATE EXTREMELY DANGEROUS SURF IS OCCURRING. MANY THANKS TO THE SAVANNAH MEDIA FOR RELAYING PICTURES AND REPORTS TO US. ANY ADDITIONAL REPORTS WOULD BE GREATLY APPRECIATED. A COASTAL FLOOD WATCH WILL REMAIN IN EFFECT BEGINNING WITH THE HIGH TIDE CYCLE TONIGHT AND CONTINUING THROUGH MONDAY NIGHT. A HIGH SURF ADVISORY IS ALREADY IN EFFECT FOR NORTHERN COASTAL GEORGIA WITH TYBEE LIFEGUARD OFFICIALS REPORTING 5 FT BREAKERS AT LAST CHECK. A HIGH SURF ADVISORY MAY BE NEEDED FOR SOUTHERN COASTAL SOUTH CAROLINA BY TONIGHT OR MONDAY. PRELIMINARY THOUGHTS ARE TO EXPAND THE ADVISORY NORTH UP TO EDISTO BEACH...BUT WILL FINALIZE THAT LATER THIS AFTERNOON. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...HIGH SURF ADVISORY UNTIL 6 PM EDT MONDAY FOR GAZ117-119-139- 141. COASTAL FLOOD WATCH FROM 9 PM EDT THIS EVENING THROUGH LATE MONDAY NIGHT FOR GAZ117-119-139-141. SC...COASTAL FLOOD WATCH FROM 9 PM EDT THIS EVENING THROUGH LATE MONDAY NIGHT FOR SCZ048>051. LAKE WIND ADVISORY UNTIL 11 AM EDT MONDAY FOR SCZ045. MARINE...SMALL CRAFT ADVISORY UNTIL 5 AM EDT WEDNESDAY FOR AMZ350-352- 354. SMALL CRAFT ADVISORY UNTIL 5 AM EDT THURSDAY FOR AMZ374. SMALL CRAFT ADVISORY UNTIL 6 PM EDT MONDAY FOR AMZ330. && $$ ST/REV ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1217 PM CDT SUN SEP 30 2007 .DISCUSSION... ISSUED 1019 AM CDT SUN SEP 30 2007 ONLY SLIGHT MODIFICATIONS THIS MORNING TO ACCOUNT FOR 7K FT DECK OVER SOUTHERN ILLINOIS ADVECTING INTO LWV AREA. WOULD EXPECT THAT THIS AREA SHOULD EVENTUALLY DISSAPATE BUT MAY BE INDICATIVE OF ENOUGH MOISTURE TO DEVELOP SCATTERED CUMULUS. HAVE ADJUSTED SKY COVER GRIDS UPWARD AND SENT UPDATED ZFP TO REFLECT INCREASED CLOUDS. ONLY OTHER CHANGE IS TO REDUCE WIND GUSTS A TAD NEXT FEW HOURS AS WINCHESTER PROFILER AND VWP SUGGEST THAT THE STRONGER GUSTS PROBABLY WILL HOLD OFF UNTIL EARLY AFTERNOON. OTHERWISE LAMP AND MET BOTH SUGGEST CURRENT FORECAST ON TRACK WITH TEMPS EXPECTED TO BE 10-15 DEGREES ABOVE NORMAL TODAY. BARKER && .AVIATION... ISSUED 1216 PM CDT SUN SEP 30 2007 TERMINAL FORECASTS FOR 18Z WILL REFLECT A SLIGHT SLOW DOWN IN PRECIP ONSET AND FONTAL PASSAGE TONIGHT COMPARED WITH 12Z PACKAGE. INITIAL TSRA WINDOW NOW EXPECTED TO BEGIN AROUND 03Z IN PIA AND 05Z IN CMI. UNTIL THEN WINDS WILL BE BIGGEST AVIATION HAZARD. IT APPEARS THAT 850-925MB MOMENTUM EVIDENT AT WINCHESTER PROFILER THROUGH THE MORNING NOW BEGINNING TO WORK DOWN AND GUSTINESS NOW REACHING THE SURFACE. THIS WAS A BIT SLOWER THAN ORIGINAL PROJECTIONS...BUT GUSTS AT 17Z WERE IN THE 21-27 KT RANGE AT THE TERMINAL POINTS. FOLLOWING FRONTAL PASSAGE LATE TONIGHT...MODELS ARE CONSISTENT IN BRINING IN SOME LOW WRAP-AROUND MOISTURE AS DEEP MID-LEVEL LOW PULLS OUT ACROSS THE GREAT LAKES. WILL KEEP LOW CIGS AND GUSTY WEST WINDS IN FORECAST THROUGH 18Z. BARKER && .PREV DISCUSSION... ISSUED 345 AM CDT SUN SEP 30 2007 A SERIES OF VIGOROUS SHORTWAVE TROUGHS WILL SWING THROUGH THE MIDWEST OVER THE NEXT SEVERAL DAYS. PRIMARY FORECAST CONCERNS ARE WITH GUSTY WINDS THIS AFTERNOON... PRECIP AND THUNDERSTORM CHANCES TONIGHT WITH STRONG SYSTEM MOVING THROUGH VERSUS LACK OF MOISTURE... FOLLOWED BY THE TIMING NEXT SYSTEM MOVING THROUGH LATE TUESDAY. SHORT TERM...TODAY THROUGH TUESDAY. STRONG NEUTRAL TILT SHORTWAVE TROUGH IS MOVING ACROSS THE ROCKIES THIS MORNING... WITH RUC ANALYSIS SHOWING AND WATER VAPOR IMAGERY SUPPORTING... A CLOSED MID-LEVEL LOW OVER CENTRAL COLORADO. LEE CYCLONE TAKING SHAPE OVER SOUTHEAST COLORADO AS WELL... WITH 3 AND 6-HR ISALLOBARS SUGGESTING THIS WILL MOVE NORTHEASTWARD INTO SW NEBRASKA THIS MORNING. DESPITE STRONG LOW LEVEL JET ACROSS THE PLAINS... LOW LEVEL MOISTURE ADVECTION REMAINS FAIRLY WEAK. SOLID 60S SFC DEWPOINTS REMAIN ACROSS TEXAS... THOUGH SFC OBS SUGGEST WE ARE FINALLY SEEING A DEEPER LOW LEVEL MOISTURE AXIS TAKING SHAPE ACROSS THE TX PANHANDLE. EAST OF THE MISSISSIPPI RIVER... WE ARE STILL VERY MUCH UNDER CONTROL OF SPRAWLING HIGH PRESSURE TO OUR EAST... WHICH HAS KEPT THE AIRMASS VERY DRY ACROSS THE REGION. SFC RIDGE AXIS ARCING TO THE SOUTHWEST HAS ALSO KEPT THE GULF MORE OR LESS CLOSED OFF FOR THE PAST SEVERAL DAYS... THUS THE VERY NARROW MOIST AXIS. VERY LITTLE CHANGES TO THE FORECAST REASONING FROM THE PAST FEW SHIFTS. STRONG/DYNAMIC SYSTEM WILL BE MOVING THROUGH... WITH VERY LITTLE MOISTURE TO WORK WITH... ESPECIALLY THIS SIDE OF THE MISSISSIPPI. SPC 4KM WRF-NMM SUPPORTS PREVIOUS THINKING WITH A NARROW SQUALL LINE APPROACHING THE MISS RIVER LATE THIS AFTERNOON/EARLY THIS EVENING... THEN RAPIDLY WEAKENING INTO SCATTERED SHOWERS SOON THERE AFTER. KEPT POPS PRETTY MUCH THE SAME... HIGHEST IN THE FAR WEST... TAPERING OFF QUICKLY TO THE EAST. VERY NARROW WINDOW WHERE STRONG LIFT WILL MAKE THE MOST OF WHAT MEAGER MOISTURE IS AVAILABLE... AND ANY RAINFALL IS NOT EXPECTED TO LAST VERY LONG AS THE FRONT WILL BE HAULING THROUGH. HOWEVER... INCREASING PRESSURE GRADIENT THIS AFTERNOON... AND H85 WINDS INCREASING TO 40-45 KTS... COMBINED WITH EFFICIENT MIXING IN A DRY ATMOSPHERE... WILL ALLOW FOR SOME GUSTY CONDITIONS THIS AFTERNOON. NOTED WIND GUSTS OVER NE/KS YESTERDAY AFTERNOON WERE MAINLY IN THE 25-35 KT RANGE. MODELS SUGGEST STRONGEST CORE OF LOW LEVEL JET WILL REMAIN TO OUR NORTHWEST... WITH H85 WINDS DECREASING SLIGHTLY THIS AFTERNOON PER NORMAL DIURNAL TRENDS. SOUNDINGS SUGGEST MIXING TO AROUND H85... SIMILAR TO CONDITIONS OVER THE HIGHER-ELEVATION GREAT PLAINS YESTERDAY. CONSIDERING ALL THIS... EXPECT WIND GUSTS WILL REMAIN BELOW WIND ADVISORY CRITERIA... GENERALLY BETWEEN 25-30 KTS ACROSS THE AREA... WITH ISOLATED GUSTS AROUND 35 KTS/40 MPH IN TYPICALLY WINDIER LOCATIONS... SUCH AS KBMI. MONDAY LOOKS DRY WITH BRIEF SHORTWAVE RIDGING COMING THROUGH... BUT WE COULD SEE SOME STUBBORN STRATOCU DEVELOP AND STICK AROUND THE NORTHERN HALF OF THE CWA... HOLDING TEMPERATURES BACK A FEW DEGREES. TIMING OF THE NEXT SYSTEM IS TRENDING SLIGHTLY FASTER... WITH GFS/ECMWF SOLUTIONS MORE OR LESS KEEPING PACE WITH ONE ANOTHER... AND THE NAM REMAINING A SLOW OUTLIER. HAVE THEREFORE MODESTLY INCREASED POPS ACROSS THE WEST FOR TUESDAY AFTERNOON. BULK OF PRECIP WILL LIKELY MOVE THROUGH THE AREA TUE NIGHT. SECOND SYSTEM NOT QUITE AS STRONG AS THE FIRST... BUT WILL BE A LITTLE MORE BROAD AND NOT QUITE AS MUCH OF A QUICK HITTER. GFS SUGGESTS PREFRONTAL TROUGH KICKING OFF CONVECTION LATE TUE AFTERNOON ACROSS THE MISSISSIPPI VALLEY... THEN SPREADING THIS EAST DURING THE OVERNIGHT HOURS. MOISTURE SHOULD BE A LITTLE BETTER THE SECOND TIME AROUND... BUT STILL NOT OVERLY IMPRESSED WITH LOW LEVEL MOISTURE RETURN POTENTIAL. THE DIFFERENCE HERE IS THAT THE MODELS HAVE BEEN CONSISTENT IN INDICATING THIS SECOND SYSTEM WILL DRAW UP SOME SUBTROPICAL MID/UPPER-LEVEL MOISTURE FROM SOUTH OF BAJA CALIFORNIA. SEVERE WEATHER WILL ALSO BE POSSIBLE... ESPECIALLY ACROSS THE FAR WEST TUE AFTERNOON. SOME CONCERN THAT THE SUBTROPICAL MOISTURE TAP MAY RESULT IN WIDESPREAD CIRRUS SHIELD OVER THE AREA TUESDAY WHICH MAY LIMIT INSTABILITY TO SOME DEGREE... BUT DYNAMICS AND SHEAR WILL MORE THAN MAKE UP FOR IT. CONVECTION COULD START AS SUPERCELLS KICKED OFF BY THE PREFRONTAL TROUGH... MOST LIKELY WEST OF OUR AREA TUE AFTERNOON... QUICKLY MERGING INTO ANOTHER SQUALL LINE AS THE MAIN SHORTWAVE AND ATTENDANT SFC COLD FRONT CATCHES UP. FRONTAL PASSAGE WOULD BE AFTER DARK ACROSS MUCH OF OUR AREA... WHICH MAY HELP LIMIT SVR POTENTIAL TO SOME DEGREE DEPENDING ON THE AMOUNT OF STABILIZATION THAT CAN OCCUR. MODELS SUGGEST WEAKER SFC LOW MOVING WELL TO OUR NORTHWEST... THUS SFC GRADIENT WINDS WILL NOT BE QUITE AS STRONG... AND MAY THEREFORE NOT KEEP BOUNDARY LAYER MIXED UP ENOUGH AFTER SUNSET. LONG TERM...WEDNESDAY THROUGH SATURDAY. DRIER WX RETURNS AGAIN FOR WEDNESDAY AND INTO THE END OF THE WORKWEEK... BUT TEMPERATURES WILL STILL REMAIN ABOVE NORMAL FOR THIS TIME OF YEAR. STRONG WAVES THAT WILL BE MOVING THROUGH THIS WEEK ARE OF MORE OF A PACIFIC ORIGIN... SO NO COLD WX OUTBREAKS ON THE IMMEDIATE HORIZON. NO CHANGES WERE MADE BEYOND DAY 5. HARDIMAN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 615 AM CDT SUN SEP 30 2007 .DISCUSSION... ISSUED 345 AM CDT SUN SEP 30 2007 A SERIES OF VIGOROUS SHORTWAVE TROUGHS WILL SWING THROUGH THE MIDWEST OVER THE NEXT SEVERAL DAYS. PRIMARY FORECAST CONCERNS ARE WITH GUSTY WINDS THIS AFTERNOON... PRECIP AND THUNDERSTORM CHANCES TONIGHT WITH STRONG SYSTEM MOVING THROUGH VERSUS LACK OF MOISTURE... FOLLOWED BY THE TIMING NEXT SYSTEM MOVING THROUGH LATE TUESDAY. SHORT TERM...TODAY THROUGH TUESDAY. STRONG NEUTRAL TILT SHORTWAVE TROUGH IS MOVING ACROSS THE ROCKIES THIS MORNING... WITH RUC ANALYSIS SHOWING AND WATER VAPOR IMAGERY SUPPORTING... A CLOSED MID-LEVEL LOW OVER CENTRAL COLORADO. LEE CYCLONE TAKING SHAPE OVER SOUTHEAST COLORADO AS WELL... WITH 3 AND 6-HR ISALLOBARS SUGGESTING THIS WILL MOVE NORTHEASTWARD INTO SW NEBRASKA THIS MORNING. DESPITE STRONG LOW LEVEL JET ACROSS THE PLAINS... LOW LEVEL MOISTURE ADVECTION REMAINS FAIRLY WEAK. SOLID 60S SFC DEWPOINTS REMAIN ACROSS TEXAS... THOUGH SFC OBS SUGGEST WE ARE FINALLY SEEING A DEEPER LOW LEVEL MOISTURE AXIS TAKING SHAPE ACROSS THE TX PANHANDLE. EAST OF THE MISSISSIPPI RIVER... WE ARE STILL VERY MUCH UNDER CONTROL OF SPRAWLING HIGH PRESSURE TO OUR EAST... WHICH HAS KEPT THE AIRMASS VERY DRY ACROSS THE REGION. SFC RIDGE AXIS ARCING TO THE SOUTHWEST HAS ALSO KEPT THE GULF MORE OR LESS CLOSED OFF FOR THE PAST SEVERAL DAYS... THUS THE VERY NARROW MOIST AXIS. VERY LITTLE CHANGES TO THE FORECAST REASONING FROM THE PAST FEW SHIFTS. STRONG/DYNAMIC SYSTEM WILL BE MOVING THROUGH... WITH VERY LITTLE MOISTURE TO WORK WITH... ESPECIALLY THIS SIDE OF THE MISSISSIPPI. SPC 4KM WRF-NMM SUPPORTS PREVIOUS THINKING WITH A NARROW SQUALL LINE APPROACHING THE MISS RIVER LATE THIS AFTERNOON/EARLY THIS EVENING... THEN RAPIDLY WEAKENING INTO SCATTERED SHOWERS SOON THERE AFTER. KEPT POPS PRETTY MUCH THE SAME... HIGHEST IN THE FAR WEST... TAPERING OFF QUICKLY TO THE EAST. VERY NARROW WINDOW WHERE STRONG LIFT WILL MAKE THE MOST OF WHAT MEAGER MOISTURE IS AVAILABLE... AND ANY RAINFALL IS NOT EXPECTED TO LAST VERY LONG AS THE FRONT WILL BE HAULING THROUGH. HOWEVER... INCREASING PRESSURE GRADIENT THIS AFTERNOON... AND H85 WINDS INCREASING TO 40-45 KTS... COMBINED WITH EFFICIENT MIXING IN A DRY ATMOSPHERE... WILL ALLOW FOR SOME GUSTY CONDITIONS THIS AFTERNOON. NOTED WIND GUSTS OVER NE/KS YESTERDAY AFTERNOON WERE MAINLY IN THE 25-35 KT RANGE. MODELS SUGGEST STRONGEST CORE OF LOW LEVEL JET WILL REMAIN TO OUR NORTHWEST... WITH H85 WINDS DECREASING SLIGHTLY THIS AFTERNOON PER NORMAL DIURNAL TRENDS. SOUNDINGS SUGGEST MIXING TO AROUND H85... SIMILAR TO CONDITIONS OVER THE HIGHER-ELEVATION GREAT PLAINS YESTERDAY. CONSIDERING ALL THIS... EXPECT WIND GUSTS WILL REMAIN BELOW WIND ADVISORY CRITERIA... GENERALLY BETWEEN 25-30 KTS ACROSS THE AREA... WITH ISOLATED GUSTS AROUND 35 KTS/40 MPH IN TYPICALLY WINDIER LOCATIONS... SUCH AS KBMI. MONDAY LOOKS DRY WITH BRIEF SHORTWAVE RIDGING COMING THROUGH... BUT WE COULD SEE SOME STUBBORN STRATOCU DEVELOP AND STICK AROUND THE NORTHERN HALF OF THE CWA... HOLDING TEMPERATURES BACK A FEW DEGREES. TIMING OF THE NEXT SYSTEM IS TRENDING SLIGHTLY FASTER... WITH GFS/ECMWF SOLUTIONS MORE OR LESS KEEPING PACE WITH ONE ANOTHER... AND THE NAM REMAINING A SLOW OUTLIER. HAVE THEREFORE MODESTLY INCREASED POPS ACROSS THE WEST FOR TUESDAY AFTERNOON. BULK OF PRECIP WILL LIKELY MOVE THROUGH THE AREA TUE NIGHT. SECOND SYSTEM NOT QUITE AS STRONG AS THE FIRST... BUT WILL BE A LITTLE MORE BROAD AND NOT QUITE AS MUCH OF A QUICK HITTER. GFS SUGGESTS PREFRONTAL TROUGH KICKING OFF CONVECTION LATE TUE AFTERNOON ACROSS THE MISSISSIPPI VALLEY... THEN SPREADING THIS EAST DURING THE OVERNIGHT HOURS. MOISTURE SHOULD BE A LITTLE BETTER THE SECOND TIME AROUND... BUT STILL NOT OVERLY IMPRESSED WITH LOW LEVEL MOISTURE RETURN POTENTIAL. THE DIFFERENCE HERE IS THAT THE MODELS HAVE BEEN CONSISTENT IN INDICATING THIS SECOND SYSTEM WILL DRAW UP SOME SUBTROPICAL MID/UPPER-LEVEL MOISTURE FROM SOUTH OF BAJA CALIFORNIA. SEVERE WEATHER WILL ALSO BE POSSIBLE... ESPECIALLY ACROSS THE FAR WEST TUE AFTERNOON. SOME CONCERN THAT THE SUBTROPICAL MOISTURE TAP MAY RESULT IN WIDESPREAD CIRRUS SHIELD OVER THE AREA TUESDAY WHICH MAY LIMIT INSTABILITY TO SOME DEGREE... BUT DYNAMICS AND SHEAR WILL MORE THAN MAKE UP FOR IT. CONVECTION COULD START AS SUPERCELLS KICKED OFF BY THE PREFRONTAL TROUGH... MOST LIKELY WEST OF OUR AREA TUE AFTERNOON... QUICKLY MERGING INTO ANOTHER SQUALL LINE AS THE MAIN SHORTWAVE AND ATTENDANT SFC COLD FRONT CATCHES UP. FRONTAL PASSAGE WOULD BE AFTER DARK ACROSS MUCH OF OUR AREA... WHICH MAY HELP LIMIT SVR POTENTIAL TO SOME DEGREE DEPENDING ON THE AMOUNT OF STABILIZATION THAT CAN OCCUR. MODELS SUGGEST WEAKER SFC LOW MOVING WELL TO OUR NORTHWEST... THUS SFC GRADIENT WINDS WILL NOT BE QUITE AS STRONG... AND MAY THEREFORE NOT KEEP BOUNDARY LAYER MIXED UP ENOUGH AFTER SUNSET. LONG TERM...WEDNESDAY THROUGH SATURDAY. DRIER WX RETURNS AGAIN FOR WEDNESDAY AND INTO THE END OF THE WORKWEEK... BUT TEMPERATURES WILL STILL REMAIN ABOVE NORMAL FOR THIS TIME OF YEAR. STRONG WAVES THAT WILL BE MOVING THROUGH THIS WEEK ARE OF MORE OF A PACIFIC ORIGIN... SO NO COLD WX OUTBREAKS ON THE IMMEDIATE HORIZON. NO CHANGES WERE MADE BEYOND DAY 5. HARDIMAN && .AVIATION... ISSUED 615 AM CDT SUN SEP 30 2007 VFR CONDITIONS WILL PREVAIL THROUGH 00Z MON. AN INCREASING PRESSURE GRADIENT AHEAD OF THE DEVELOPING PLAINS LOW PRESSURE SYSTEM WILL RESULT IN SOUTH TO SOUTHWESTERLY WINDS 15-20 KT SUSTAINED...WITH GUSTS AROUND 30 KT AFTER 18Z SUN. THE DEVELOPING PLAINS LOW WILL MOVE TO NORTHERN IOWA BY 00Z MONDAY...WITH A COLD FRONT TRAILING SOUTHWARD AND APPROACHING THE MISSISSIPPI RIVER. A 20-30 MILE WIDE BAND OF CONVECTION IS EXPECTED WITH THE FRONT AS IT SWEEPS THROUGH THE CENTRAL ILLINOIS TAF SITES 04Z-08Z MON. CEILINGS SHOULD REMAIN VFR EXCEPT WITHIN CONVECTION...WHERE MVFR/BRIEF IFR CONDITIONS WILL BE LIKELY. STRATOCU WILL THEN MOVE INTO THE AREA BEHIND THE COLD FRONT AND LINGER BEYOND 12Z MON...WITH CEILINGS RIGHT AROUND THE 3K LEVEL. 04 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 130 PM EDT SUN SEP 30 2007 .AVIATION... COLD FRONT WILL APPROACH THE AREA OVERNIGHT. CLEAR SKIES THROUGH EARLY THIS EVENING BEFORE MID AND HIGH CLOUDS BEGIN TO INCREASE AND LOWER. STRONG LOW LEVEL JET DEVELOPING IN REGION OF 850MB THETA E AXIS SHOULD ALLOW NARROW LINE OF SHOWERS AND EMBEDDED TSRA TO DEVELOP. TIMING STILL FAVORS 06-09Z AT KSBN AND 09-12Z AT KFWA. KEPT CB MENTION RATHER THAN PREVALING TSRA DUE TO UNCERTAINTY OF COVERAGE GIVEN NARROW CHANNEL OF DEEPER MOISTURE AND OVERNIGHT TIMING. UPPER LEVEL TROUGH AND COLD POOL TO MOVE ACROSS AREA MONDAY ALONG WITH EMBEDDED VORT MAX IN TROUGH. INSTABILITY SHOWERS AND MVFR CIGS EXPECTED THROUGH 18Z. && .SHORT TERM (TODAY AND TONIGHT)... MODELS HAVE BEEN SOMEWHAT JUMPY WITH THE TIMING OF THE COLD FRONT LATE TONIGHT INTO EARLY MONDAY...3 TO 6 HOURS SLOWER TONIGHT THAN PREVIOUS RUN...SLOWER STILL FROM YSTDY`S RUNS. HAVE STARTED OUT LEANING TOWARDS THE RUC THRU THE FIRST PERIOD...THEN BLENDED TOWARDS THE MORE CONSISTENT OF THE OPERATIONAL MODELS...WHICH IS THE GFS. SURFACE HIGH SETTLED ACROSS THE FAR NE STATES...WITH UPPER LEVEL RIDGE CENTERED ACROSS THE GULF STATES INTO THE GREAT LAKES THIS MORNING. THE RIDGE WILL START TO SHIFT TO THE EAST THIS AFTERNOON WITH THE AXIS REACHING THE APP MTNS. INCREASING GRADIENT FLOW AHEAD OF THE DEVELOPING SYSTEM ACROSS THE PLAINS...AND MODERATE LOW LEVEL JET THAT WILL START TO MIX DOWN SOME WITH THE HEATING OF THE DAY. WINDS WILL BECOME GUSTY THIS AFTERNOON...WITH GUSTS UP TO 25 OR 30 MPH POSSIBLE ON THE HIGH END. FILTERED SUNSHINE AS CI BLOW-OFF WILL MOVE ACROSS THE SKIES...MAY THIN SOME LATER IN THE AFTERNOON. VERY WARM H850 TEMPS FOR THE LAST DAY OF SEPT...AROUND 13 OR 14C...WELL ABOVE THE NORMAL OF 8 OR 9C. THESE WARM TEMPS ALOFT WILL HELP PRODUCE AFTN HIGHS IN THE UPPER 70S TO AROUND 80 AREAWIDE...NEARLY 10 TO 14 DEGREES ABOVE NORMAL FOR THE DATE. AS THE RIDGE EXITS TO THE EAST THE VIGOROUS TROUGH WILL PUSH EAST FROM THE PLAINS DURING THE EVENING...TIGHTENING PRESSURE GRADIENT WILL CONTINUE THE MODERATE AND GUSTY WINDS. INCREASING HIGH AND SOME MID LEVEL CLOUDS EXPECTED AS WE APPROACH MIDNIGHT. COMBINATION OF THE WINDS AND THE INCREASE IN CLOUD COVER WILL KEEP TEMPS UP TO ABOVE NORMAL LEVELS. LOWS WILL STRUGGLE TO DROP BELOW THE LOWER 60S ACROSS THE REGION. AS THE TROUGH AND ASSOCIATED COLD FRONT MOVES INTO THE REGION AFTER 06Z...SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE. FORECAST SOUNDINGS STILL NOT IMPRESSIVE AT ALL WITH EITHER MOISTURE CONTENT...OR INSTABILITY...BUT BUFKIT IS SHOWING SOME ELEVATED CAPE. PWATS ONLY TOP OUT ABOUT 1.2 TO 1.3 INCHES ALONG THE BOUNDARY...WHICH IS ABOUT 130 PERCENT OF NORMAL. BUT THE STRENGTH OF THE SHRTWV MAY EASILY OVERCOME THESE FACTORS...AS CURRENTLY SEEN ACROSS THE PLAINS TONIGHT. WITH H925 WINDS OVERNIGHT NEAR 40 KNOTS AS PER THE GFS...IF DECENT CONVECTION CAN BREAK OUT MIXING DOWN OF SOME DECENT GUSTS MAY BE POSSIBLE...THOUGH APPROACHING SEVERE LIMITS LOOKS UNLIKELY AS DECENT INVERSION/STABLE LAYER NEAR THE SURFACE SHOULD BE IN PLACE. PRECIP MAY BE MAINLY VIRGA AT FIRST AS IT WILL TAKE SOME TIME TO MOISTEN THE LOWER LEVELS OVERNIGHT...PRECIP CHANCES TO OVERSPREAD THE REGION AFTER MIDNIGHT INTO DAYBREAK. PRECIP TOTALS WILL BE HIGHER ACROSS THE NORTHWESTERN PORTIONS OF THE AREA DURING THE PERIOD...WITH MUCH LIGHTER TOTALS ELSEWHERE. && .LONG TERM (MONDAY THROUGH SATURDAY)... ENERGETIC PATTN IN STORE THIS WEEK AS WAVE TRAIN OF POTENT NRN STREAM SW TROUGHS MIGRATE ACRS THE CONUS. LEAD SYS EJECTING OUT OF CO THIS MORNING SPURNING INTENSE CONVN ACRS SD/MN ALG NOSE OF EMERGING YET TEMPERED GOMEX RTN. 00Z MODEL SOLUTIONS IN CLOSE AGREEMENT TAKING INITIALLY INTENSE COLD CORE MID LVL WAVE EWD INTO THE WRN LAKES BY MON AFTN. DIURNAL TIMING OF COLD POCKET ALOFT AND RTN LL MSTR WEDGE SUGGEST THUNDER PSBL MON. OTHERWISE TEMPERED TEMPS FURTHER W/DEEPENING MSTR/CLDS AND INCREASING RAIN CHCS. AFT THAT...SHRT AMPLITUDE RIDGING BUILDS QUICKLY TUE W/TEMPS SOARING WELL ABV NORMAL AHD OF SECONDARY UPSTREAM SW OFF THE PAC NW COAST THIS MORNING STILL SLATED TO ARRIVE TUE NIGHT. NOT PARTICULARLY SOLD YET ON TIMING OF THIS SYS AND WILL MAKE FEW CHGS HERE ESP GIVEN INTENSE LOOK PER VAPOR AND ALL TO COMMON SHARED MODEL BIAS OF PROGRESSING THESE SYSTEMS EWD TOO FAST. BEYOND THAT...ANOMALOUS SUB TROPICAL RIDGE OF LATE REBUILDS ACRS THE SE US IN RESPONSE TO INTENSE SW OVR THE BEARING SEA THIS MORNING. INTERESTINGLY BOTH THE 00Z RUNS OF THE ECMWF/GFS HANDLE THIS SYS SIMILARLY AS THEY BOTH DVLP A VRY INTENSE CYCLONE OVR THE MID MISSISSIPPI VALLEY EARLY NXT WEEK. TEMPS LATE WEEK/NXT WEEKEND XPCD TO CONT WELL ABV NORMAL. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...SCHOTT LONG TERM...HOLSTEN AVIATION...LASHLEY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 730 AM EDT SUN SEP 30 2007 .AVIATION... GENERALLY CONTINUED WITH PREVIOUS THINKING. LOW LEVEL WIND SHEAR MARGINAL BUT KIWX PROFILER SHOWING 20 TO 25 KNOTS AT 2KFT AND SURFACE WINDS STILL 4 TO 6 KNOTS. MIXING WITH SUNRISE SHOULD QUICKLY ALLOW SURFACE WINDS TO INCREASE AND BECOME MORE SOUTHERLY ENDING LOW LEVEL WIND SHEAR THREAT. 10 TO 20 KNOT WINDS EXPECTED TODAY. SURFACE COLD FRONT WILL APPROACH THE AREA OVERNIGHT WITH LINE OF BROKEN SHOWERS AND EMBEDDED TSRA EXPECTED...NEARING KSBN BETWEEN 06-09Z AND KFWA 09-12Z. HAVE ADDED AN MVFR RESTRICTION TO KSBN BUT TIMING AND WEAKENING NATURE TO FRONT MAKES MVFR QUESTIONABLE AT KFWA AT THIS TIME FRAME. STAYED MORE OPTIMISTIC THERE WITH NON RESTRICTED SHRA AND VFR CIG. && .SHORT TERM (TODAY AND TONIGHT)... MODELS HAVE BEEN SOMEWHAT JUMPY WITH THE TIMING OF THE COLD FRONT LATE TONIGHT INTO EARLY MONDAY...3 TO 6 HOURS SLOWER TONIGHT THAN PREVIOUS RUN...SLOWER STILL FROM YSTDY`S RUNS. HAVE STARTED OUT LEANING TOWARDS THE RUC THRU THE FIRST PERIOD...THEN BLENDED TOWARDS THE MORE CONSISTENT OF THE OPERATIONAL MODELS...WHICH IS THE GFS. SURFACE HIGH SETTLED ACROSS THE FAR NE STATES...WITH UPPER LEVEL RIDGE CENTERED ACROSS THE GULF STATES INTO THE GREAT LAKES THIS MORNING. THE RIDGE WILL START TO SHIFT TO THE EAST THIS AFTERNOON WITH THE AXIS REACHING THE APP MTNS. INCREASING GRADIENT FLOW AHEAD OF THE DEVELOPING SYSTEM ACROSS THE PLAINS...AND MODERATE LOW LEVEL JET THAT WILL START TO MIX DOWN SOME WITH THE HEATING OF THE DAY. WINDS WILL BECOME GUSTY THIS AFTERNOON...WITH GUSTS UP TO 25 OR 30 MPH POSSIBLE ON THE HIGH END. FILTERED SUNSHINE AS CI BLOW-OFF WILL MOVE ACROSS THE SKIES...MAY THIN SOME LATER IN THE AFTERNOON. VERY WARM H850 TEMPS FOR THE LAST DAY OF SEPT...AROUND 13 OR 14C...WELL ABOVE THE NORMAL OF 8 OR 9C. THESE WARM TEMPS ALOFT WILL HELP PRODUCE AFTN HIGHS IN THE UPPER 70S TO AROUND 80 AREAWIDE...NEARLY 10 TO 14 DEGREES ABOVE NORMAL FOR THE DATE. AS THE RIDGE EXITS TO THE EAST THE VIGOROUS TROUGH WILL PUSH EAST FROM THE PLAINS DURING THE EVENING...TIGHTENING PRESSURE GRADIENT WILL CONTINUE THE MODERATE AND GUSTY WINDS. INCREASING HIGH AND SOME MID LEVEL CLOUDS EXPECTED AS WE APPROACH MIDNIGHT. COMBINATION OF THE WINDS AND THE INCREASE IN CLOUD COVER WILL KEEP TEMPS UP TO ABOVE NORMAL LEVELS. LOWS WILL STRUGGLE TO DROP BELOW THE LOWER 60S ACROSS THE REGION. AS THE TROUGH AND ASSOCIATED COLD FRONT MOVES INTO THE REGION AFTER 06Z...SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE. FORECAST SOUNDINGS STILL NOT IMPRESSIVE AT ALL WITH EITHER MOISTURE CONTENT...OR INSTABILITY...BUT BUFKIT IS SHOWING SOME ELEVATED CAPE. PWATS ONLY TOP OUT ABOUT 1.2 TO 1.3 INCHES ALONG THE BOUNDARY...WHICH IS ABOUT 130 PERCENT OF NORMAL. BUT THE STRENGTH OF THE SHRTWV MAY EASILY OVERCOME THESE FACTORS...AS CURRENTLY SEEN ACROSS THE PLAINS TONIGHT. WITH H925 WINDS OVERNIGHT NEAR 40 KNOTS AS PER THE GFS...IF DECENT CONVECTION CAN BREAK OUT MIXING DOWN OF SOME DECENT GUSTS MAY BE POSSIBLE...THOUGH APPROACHING SEVERE LIMITS LOOKS UNLIKELY AS DECENT INVERSION/STABLE LAYER NEAR THE SURFACE SHOULD BE IN PLACE. PRECIP MAY BE MAINLY VIRGA AT FIRST AS IT WILL TAKE SOME TIME TO MOISTEN THE LOWER LEVELS OVERNIGHT...PRECIP CHANCES TO OVERSPREAD THE REGION AFTER MIDNIGHT INTO DAYBREAK. PRECIP TOTALS WILL BE HIGHER ACROSS THE NORTHWESTERN PORTIONS OF THE AREA DURING THE PERIOD...WITH MUCH LIGHTER TOTALS ELSEWHERE. && .LONG TERM (MONDAY THROUGH SATURDAY)... ENERGETIC PATTN IN STORE THIS WEEK AS WAVE TRAIN OF POTENT NRN STREAM SW TROUGHS MIGRATE ACRS THE CONUS. LEAD SYS EJECTING OUT OF CO THIS MORNING SPURNING INTENSE CONVN ACRS SD/MN ALG NOSE OF EMERGING YET TEMPERED GOMEX RTN. 00Z MODEL SOLUTIONS IN CLOSE AGREEMENT TAKING INITIALLY INTENSE COLD CORE MID LVL WAVE EWD INTO THE WRN LAKES BY MON AFTN. DIURNAL TIMING OF COLD POCKET ALOFT AND RTN LL MSTR WEDGE SUGGEST THUNDER PSBL MON. OTHERWISE TEMPERED TEMPS FURTHER W/DEEPENING MSTR/CLDS AND INCREASING RAIN CHCS. AFT THAT...SHRT AMPLITUDE RIDGING BUILDS QUICKLY TUE W/TEMPS SOARING WELL ABV NORMAL AHD OF SECONDARY UPSTREAM SW OFF THE PAC NW COAST THIS MORNING STILL SLATED TO ARRIVE TUE NIGHT. NOT PARTICULARLY SOLD YET ON TIMING OF THIS SYS AND WILL MAKE FEW CHGS HERE ESP GIVEN INTENSE LOOK PER VAPOR AND ALL TO COMMON SHARED MODEL BIAS OF PROGRESSING THESE SYSTEMS EWD TOO FAST. BEYOND THAT...ANOMALOUS SUB TROPICAL RIDGE OF LATE REBUILDS ACRS THE SE US IN RESPONSE TO INTENSE SW OVR THE BEARING SEA THIS MORNING. INTERESTINGLY BOTH THE 00Z RUNS OF THE ECMWF/GFS HANDLE THIS SYS SIMILARLY AS THEY BOTH DVLP A VRY INTENSE CYCLONE OVR THE MID MISSISSIPPI VALLEY EARLY NXT WEEK. TEMPS LATE WEEK/NXT WEEKEND XPCD TO CONT WELL ABV NORMAL. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...SCHOTT LONG TERM...HOLSTEN AVIATION...LASHLEY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 413 AM EDT SUN SEP 30 2007 .SHORT TERM (TODAY AND TONIGHT)... MODELS HAVE BEEN SOMEWHAT JUMPY WITH THE TIMING OF THE COLD FRONT LATE TONIGHT INTO EARLY MONDAY...3 TO 6 HOURS SLOWER TONIGHT THAN PREVIOUS RUN...SLOWER STILL FROM YSTDY`S RUNS. HAVE STARTED OUT LEANING TOWARDS THE RUC THRU THE FIRST PERIOD...THEN BLENDED TOWARDS THE MORE CONSISTENT OF THE OPERATIONAL MODELS...WHICH IS THE GFS. SURFACE HIGH SETTLED ACROSS THE FAR NE STATES...WITH UPPER LEVEL RIDGE CENTERED ACROSS THE GULF STATES INTO THE GREAT LAKES THIS MORNING. THE RIDGE WILL START TO SHIFT TO THE EAST THIS AFTERNOON WITH THE AXIS REACHING THE APP MTNS. INCREASING GRADIENT FLOW AHEAD OF THE DEVELOPING SYSTEM ACROSS THE PLAINS...AND MODERATE LOW LEVEL JET THAT WILL START TO MIX DOWN SOME WITH THE HEATING OF THE DAY. WINDS WILL BECOME GUSTY THIS AFTERNOON...WITH GUSTS UP TO 25 OR 30 MPH POSSIBLE ON THE HIGH END. FILTERED SUNSHINE AS CI BLOW-OFF WILL MOVE ACROSS THE SKIES...MAY THIN SOME LATER IN THE AFTERNOON. VERY WARM H850 TEMPS FOR THE LAST DAY OF SEPT...AROUND 13 OR 14C...WELL ABOVE THE NORMAL OF 8 OR 9C. THESE WARM TEMPS ALOFT WILL HELP PRODUCE AFTN HIGHS IN THE UPPER 70S TO AROUND 80 AREAWIDE...NEARLY 10 TO 14 DEGREES ABOVE NORMAL FOR THE DATE. AS THE RIDGE EXITS TO THE EAST THE VIGOROUS TROUGH WILL PUSH EAST FROM THE PLAINS DURING THE EVENING...TIGHTENING PRESSURE GRADIENT WILL CONTINUE THE MODERATE AND GUSTY WINDS. INCREASING HIGH AND SOME MID LEVEL CLOUDS EXPECTED AS WE APPROACH MIDNIGHT. COMBINATION OF THE WINDS AND THE INCREASE IN CLOUD COVER WILL KEEP TEMPS UP TO ABOVE NORMAL LEVELS. LOWS WILL STRUGGLE TO DROP BELOW THE LOWER 60S ACROSS THE REGION. AS THE TROUGH AND ASSOCIATED COLD FRONT MOVES INTO THE REGION AFTER 06Z...SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE. FORECAST SOUNDINGS STILL NOT IMPRESSIVE AT ALL WITH EITHER MOISTURE CONTENT...OR INSTABILITY...BUT BUFKIT IS SHOWING SOME ELEVATED CAPE. PWATS ONLY TOP OUT ABOUT 1.2 TO 1.3 INCHES ALONG THE BOUNDARY...WHICH IS ABOUT 130 PERCENT OF NORMAL. BUT THE STRENGTH OF THE SHRTWV MAY EASILY OVERCOME THESE FACTORS...AS CURRENTLY SEEN ACROSS THE PLAINS TONIGHT. WITH H925 WINDS OVERNIGHT NEAR 40 KNOTS AS PER THE GFS...IF DECENT CONVECTION CAN BREAK OUT MIXING DOWN OF SOME DECENT GUSTS MAY BE POSSIBLE...THOUGH APPROACHING SEVERE LIMITS LOOKS UNLIKELY AS DECENT INVERSION/STABLE LAYER NEAR THE SURFACE SHOULD BE IN PLACE. PRECIP MAY BE MAINLY VIRGA AT FIRST AS IT WILL TAKE SOME TIME TO MOISTEN THE LOWER LEVELS OVERNIGHT...PRECIP CHANCES TO OVERSPREAD THE REGION AFTER MIDNIGHT INTO DAYBREAK. PRECIP TOTALS WILL BE HIGHER ACROSS THE NORTHWESTERN PORTIONS OF THE AREA DURING THE PERIOD...WITH MUCH LIGHTER TOTALS ELSEWHERE. && .LONG TERM (MONDAY THROUGH SATURDAY)... ENERGETIC PATTN IN STORE THIS WEEK AS WAVE TRAIN OF POTENT NRN STREAM SW TROUGHS MIGRATE ACRS THE CONUS. LEAD SYS EJECTING OUT OF CO THIS MORNING SPURNING INTENSE CONVN ACRS SD/MN ALG NOSE OF EMERGING YET TEMPERED GOMEX RTN. 00Z MODEL SOLUTIONS IN CLOSE AGREEMENT TAKING INITIALLY INTENSE COLD CORE MID LVL WAVE EWD INTO THE WRN LAKES BY MON AFTN. DIURNAL TIMING OF COLD POCKET ALOFT AND RTN LL MSTR WEDGE SUGGEST THUNDER PSBL MON. OTHERWISE TEMPERED TEMPS FURTHER W/DEEPENING MSTR/CLDS AND INCREASING RAIN CHCS. AFT THAT...SHRT AMPLITUDE RIDGING BUILDS QUICKLY TUE W/TEMPS SOARING WELL ABV NORMAL AHD OF SECONDARY UPSTREAM SW OFF THE PAC NW COAST THIS MORNING STILL SLATED TO ARRIVE TUE NIGHT. NOT PARTICULARLY SOLD YET ON TIMING OF THIS SYS AND WILL MAKE FEW CHGS HERE ESP GIVEN INTENSE LOOK PER VAPOR AND ALL TO COMMON SHARED MODEL BIAS OF PROGRESSING THESE SYSTEMS EWD TOO FAST. BEYOND THAT...ANOMALOUS SUB TROPICAL RIDGE OF LATE REBUILDS ACRS THE SE US IN RESPONSE TO INTENSE SW OVR THE BEARING SEA THIS MORNING. INTERESTINGLY BOTH THE 00Z RUNS OF THE ECMWF/GFS HANDLE THIS SYS SIMILARLY AS THEY BOTH DVLP A VRY INTENSE CYCLONE OVR THE MID MISSISSIPPI VALLEY EARLY NXT WEEK. TEMPS LATE WEEK/NXT WEEKEND XPCD TO CONT WELL ABV NORMAL. && .PREV DISCUSSION... /ISSUED 129 AM EDT SUN SEP 30 2007/ AVIATION (06Z TAFS)... VFR TAF PERIOD UPCOMING...REGION STILL CONTROLLED BY THE LARGE UPPER LEVEL RIDGING ACROSS THE EAST. MAIN AVIATION CONCERN THROUGH THE PERIOD WILL BE THE BORDERLINE NON-CONVECTIVE LOW LEVEL WIND SHEAR THIS MORNING AND THE GUSTINESS OF THE WINDS THIS LATE MORNING INTO THE EARLY MORNING HOURS OF MONDAY AHEAD OF AN APPROACHING COLD FRONT. MODERATE LOW LEVEL JET SEEN BOTH VIA LOCAL PROFILERS AND MODELS...LOOKS TO PERSIST THRU THE MORNING. GUSTS IN THE RANGE OF 20 TO 25 KTS WILL BE LIKELY FROM LATE THIS MORNING INTO THE OVERNIGHT PERIOD. NO CIGS OR RESTRICTION TO VSBY EXPECTED THRU THE PERIOD...BUT DID MENTION VCSH AT SBN AFTER 04Z MON AS THE FRONT NEARS THE AREA. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...SCHOTT LONG TERM...HOLSTEN AVIATION...SCHOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 321 PM CDT MON OCT 1 2007 .DISCUSSION... DAYS 1-2... DISC WILL CENTER PRIMARILY ON THUNDERSTORM COVERAGE/INTENSITY TONIGHT AND WHERE MOST OF THE RAIN WILL LIKELY FALL. WV LOOP THIS AFTERNOON SHOWED A HEALTHY PLUME OF MID LEVEL MOISTURE FROM DECAYING TROPICAL SYSTEM "JULIETTE" OFF THE COAST OF BAJA...NORTHWARD THROUGH ARIZONA AND NEW MEXICO. THIS PLUME OF MOISTURE WAS ON THE NORTHWEST PERIPHERY OF STRONG MID-UPPER HIGH CENTERED OVER NORTHERN OLD MEXICO. A SUBTROPICAL JET STREAK STRETCHED FROM FAR SOUTHERN CALIFORNIA THROUGH SOUTHERN UTAH INTO WESTERN COLORADO. A POLAR JET STREAK WAS ROTATING AROUND THE EASTERN SIDE OF A TROUGH JUST NORTH OF THE SUBTROPICAL JET STREAK. AS THE AFTERNOON HAS GONE ON...RUC ANALYSIS AND WV LOOP SHOWED THESE TWO JETS MERGING. NAM, GFS, AND RUC MODELS SHOW AN INCREASING REGION OF SYNOPTIC SCALE LIFT WITHIN THE RIGHT-ENTRANCE OF THE SUBTROPICAL JET AS IT LIFTS INTO THE HIGH PLAINS. THE OLD SURFACE POLAR FRONT THAT PUSHED THROUGH YESTERDAY HAD STALLED OUT ALONG THE RED RIVER VALLEY...WITH THE WESTERN EDGE OF THE OLD WASHED OUT FRONT LIFTING BACK NORTH...SEEN PRIMARILY BY THE DEWPOINT GRADIENT IN THE SURFACE OBSERVATIONS. UPPER 50S TO NEAR 60 DEWPOINTS OVER WEST TEXAS WILL CONTINUE TO SPREAD NORTH THIS EVENING. GFS AND NAM 900-800MB DEWPOINTS OF 13-16C WILL EXIST ALONG AN AXIS CENTERED OVER THE PANHANDLES AND SOUTHWEST KANSAS AS THE NIGHT WEARS ON. WITH THE INCREASED LIFT DUE TO THE UPPER JET STREAK DYNAMICS...PLUS 40-50 KNOT LOW LEVEL JET...SCATTERED TO NUMEROUS THUNDERSTORMS ARE EXPECTED TO RESULT...DEVELOPING FIRST OVER NORTHEASTERN NEW MEXICO IN THE 03-06Z TIME FRAME...THEN SPREADING AND DEVELOPING NORTHEASTWARD TO ENCOMPASS THE SOUTHERN DDC CWA AFTER 06Z. WILL GO WITH 60 POPS FOR MUCH OF THE SOUTHERN-CENTRAL DDC CWA IN THE 08-12Z TIME FRAME...WITH 60 POPS OVER THE EASTERN ZONES IN THE 12-15Z TIME FRAME. A LOOK AT THERMODYNAMIC PROFILES IN NAM/GFS FORECAST SOUNDINGS REVEALS A FAIRLY MOIST PROFILE WITHOUT A TREMENDOUS AMOUNT OF CAPE...HOWEVER 600-1000 J/KG SHOULD BE ENOUGH TO PROMPT A FEW SMALL HAIL REPORTS. THE LOW LEVEL BOUNDARY WILL BE OVER THE FAR EASTERN DDC CWA BY MIDDAY TUESDAY WITH REDEVELOPMENT OF THUNDERSTORMS EXPECTED OVER SOUTH CENTRAL KANSAS...MAINLY EAST OF DDC CWA. A RAPID CLEARING IS EXPECTED OVER THE REMAINDER OF SOUTHWEST KANSAS BY MIDDAY AS SYNOPTIC SUBSIDENCE REIGNS. BEHIND THE FRONT...HIGHS WILL BE IN THE MID-UPPER 70S WITH LOTS OF SUN BY AFTERNOON. TUESDAY NIGHT...SURFACE HIGH CENTER WILL BE OVER WESTERN KANSAS WITH EXCELLENT RADIATIONAL COOLING CONDITIONS ALLOWING LOWS TO BOTTOM OUT IN THE MID-UPPER 40S. WEDNESDAY...MORE SUN AND WARMER WITH SUBSIDENCE PREVAILING AND A RETURN FLOW OF SOUTH WINDS BY AFTERNOON. HIGHS WILL REACH THE LOWER 80S PRETTY MUCH EVERYWHERE IN DDC CWA. -UMSCHEID DAYS 3-7... THE MAIN TROUBLE SPOT IN THE EXTENDED IS POPS FOR THE LATE WEDNESDAY INTO THURSDAY PERIODS. A SIGNIFICANT SHORT WAVE IS EVIDENT IN THE ECMWF...THE GFS AND THE NAM...EACH WITH A LITTLE DIFFERENT SPEED AND LOCATION. THE GFS REMAINS THE QUICKEST WITH THIS UPPER SYSTEM...KEEPING THE WAVE NORTH OF OUR AREA AND CARRYING IT THROUGH THE BROAD WAVE...NEAR ZONAL FLOW ACROSS THE NORTHERN PLAINS. WITH THAT TRACK...THE GFS DOES NOW PRODUCE ANY MEASURABLE PRECIPITATION FOR OUR SOUTHWEST KANSAS CWA. HOWEVER...BOTH THE NAM AND THE ECMWF PULL AN UPPER TROUGH THROUGH KANSAS INTO MISSOURI/OKLAHOMA RATHER QUICKLY TUESDAY INTO WEDNESDAY...LEAVING THE LEE SIDE OF THE ROCKIES WIDE OPEN FOR LEE SIDE TROUGH DEVELOPMENT. THIS FEATURE CROSSES SOUTHWEST KANSAS LATE WEDNESDAY INTO EARLY THURSDAY. THUS...HAVE LEFT THE 20 POPS FOR WEDNESDAY GOING...INCREASING MY EASTERN ZONES TO NEAR 30 POPS FOR WEDNESDAY NIGHT. AFTER THIS ABOVE MENTIONED UPPER WAVE PASSES...YET ANOTHER WAVE IS INDICATED BY THE EC AND ALSO THE GFS TO SWOOP DOWN FROM OUR NORTHWEST AND CROSS CENTRAL KANSAS. AM NOT AS CONFIDENT WITH THIS TRACK AS IT SEEMS TOO SOON TO GET A WAVE FROM THE NORTHWEST. DID HOWEVER LEAVE THE LOW TEEN POPS GOING FOR SATURDAY AFTERNOON AND NIGHT...WHICH CAN BE ADJUSTED UPWARD OR DOWNWARD AS THAT TIME APPROACHES THE NEARER TERM AND FUTURE MODEL RUNS CONFIRM THE UPPER LOW TRACK. FOR TEMPERATURES...STAYED FAIRLY CLOSE TO THE PREVIOUS FORECAST. DID LOW MAX TEMPS A DEGREE OR TWO ON THURSDAY AND FRIDAY...TO COME IN LINE WITH SURROUNDING ISC GRIDS BETTER. FRIDAY SHOULD BE THE WARMEST DAY WITH THE DEEP SOUTHWEST FLOW ADVECTING IN WARM LOW LEVEL AIR. MIN TEMPS WERE TAPERED DOWN FRIDAY AND SATURDAY...EXPECTING A FROPA ON THURSDAY NIGHT. && .AVIATION... AS FOR AVIATION CONCERNS...BREEZY SOUTH WINDS IN THE 18G26KT RANGE WILL CONTINUE THROUGH 01-02Z THIS EVENING...THEN BACK OFF TO SOUTH-SOUTHEASTERLY AT 15KT OR LESS. VFR MID AND HIGH SCATTERED CLOUDS WILL BEGIN INCREASING FROM THE NORTHWEST AFTER MIDNIGHT...WITH MVFR CIGS EXPECTED AFTER 09Z OR SO. BKN-OVC015 WILL BE COMMON AFTER 09Z...WITH SCATTERED RW/TRW DEVELOPING AT HYS AFTER 08Z...GCK AFTER 10Z AND DDC AFTER 12Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 64 77 49 82 / 60 70 0 0 GCK 61 77 47 83 / 50 30 0 0 EHA 58 79 51 83 / 50 30 0 0 LBL 64 79 50 84 / 60 40 0 0 HYS 66 74 47 81 / 50 60 0 0 P28 68 78 53 80 / 50 70 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN25/12/12 ks AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE GOODLAND KS 142 PM MDT SUN SEP 30 2007 .DISCUSSION...JUST COMPLETED UPDATE WHICH CANCELLED THE ADVISORY. ADJUSTED MAX TEMPERATURES A LITTLE BASED ON CURRENT OBSERVATIONS. ALSO ADJUSTED WINDS BASED ON LATEST OBSERVATIONS AND RUC. ALSO ADJUSTED OTHER HOURLY GRIDS. && .AVIATION...EXPECT NORTHWEST WINDS IN THE 20 TO 30 KNOT RANGE TO DECREASE BELOW 10 KNOTS BETWEEN 21Z AND 23Z. AT BOTH SITES...VFR CONDITIONS WILL CONTINUE THROUGH THE DAY ON MONDAY WITH LIGHT WINDS CONTINUING THROUGH 15Z MONDAY. AFTER 15Z MONDAY...EXPECT SOUTH WINDS TO INCREASE TO BETWEEN 20 AND 30 KNOTS. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 550 AM MDT SUN SEP 30 2007 .UPDATE...WINDS REACHING ADVISORY CRITERIA ACROSS EASTERN COLORADO AND SHERMAN COUNTY IN KANSAS. HAVE STARTED THE ADVISORY AT 12Z INSTEAD OF 16Z AS A RESULT. THE CURRENT WIND GUSTS MAY BE FROM THE SUDDEN PRESSURE RISE ASSOCIATED WITH THE FRONT. LATEST RUC SHOWS THE MORE SUSTAINED WINDS STILL IN NEBRASKA. HOWEVER...THEY TOO WOULD HAVE REACHED OUR AREA BEFORE THE INITIAL 16Z START TIME SO IT LOOKS GOOD NOW TO GET IT STARTED A BIT EARLIER. && .PREV DISCUSSION... /ISSUED 249 AM MDT SUN SEP 30 2007/ .UPDATE...BASED ON MY CURRENT WIND GUST GRIDS ADVISORY CRITERIA GUSTS WILL BE REACHED GENERALLY ACROSS THE NORTHERN 2/3 OF THE TRI-STATE AREA. SO...WILL BE ISSUING A WIND ADVISORY FOR SEVERAL HOURS TODAY. NO OTHER CHANGES ANTICIPATED AT THIS TIME. && .PREV DISCUSSION... /ISSUED 221 AM MDT SUN SEP 30 2007/ .DISCUSSION...FORECAST CONCERNS ARE ON THE STRENGTH OF NORTHWEST WINDS TODAY/HOW COOL IT WILL BE AND CHANCES OF PRECIPITATION. .SHORT TERM (TODAY-TUESDAY NIGHT)... TODAY-TONIGHT...A STRONG UPPER LOW PRESSURE CENTER CURRENTLY LOCATED IN NORTH CENTRAL COLORADO WILL MOVE INTO THE NORTHWEST PORTION OF THE TRI-STATE AREA THIS MORNING THEN LIFT NORTHEAST AND BY MONDAY MORNING REACH THE GREAT LAKES. 800 MB WINDS FROM THE NAM AND GFS ARE QUITE A BIT STRONGER THEN WHAT WAS ADVERTISED YESTERDAY...PERHAPS THE REASON IS THE LATEST MODELS ARE STRONGER AND A BIT FURTHER SOUTH WITH THE UPPER LOW CENTER AND ITS TRACK. LOOKS LIKE GUSTS OF 35 TO 45 MPH ARE EXPECTED WITH BEST CHANCE OF ADVISORY CRITERIA WINDS ACROSS THE EASTERN 1/2 OF THE AREA. WITH THE QUICK MOVEMENT OF THE STORM SYSTEM WINDS LOOK TO QUICKLY WEAKEN BY LATE AFTERNOON BUT STILL GUSTY. GIVEN THE EXPECTED FURTHER SOUTH TRACK WRAPAROUND PRECIP IS POSSIBLE GENERALLY NEAR THE NEBRASKA/KANSAS BORDER THROUGH EARLY AFTERNOON. WITH LITTLE TO SURFACE INSTABILITY AND WEAK LAPSE RATES ANY PRECIP THAT DOES DEVELOP SHOULD BE OF A SHOWERY TYPE. MONDAY-MONDAY NIGHT...ANOTHER LARGE AREA OF MOISTURE WILL MOVE INTO THE AREA FROM THE SOUTHWEST MONDAY NIGHT AHEAD OF ANOTHER UPPER LEVEL TROUGH WHICH BY 12Z TUESDAY SHOULD BE STILL WEST OF THE AREA. SOUTHERLY WINDS WILL INCREASE AHEAD OF THIS TROUGH WITH WINDY CONDITIONS EXPECTED. WILL GO WITH A CHANCE OF THUNDERSTORMS MONDAY NIGHT PER SURROUNDING OFFICES AND GUIDANCE QPF/POPS. TUESDAY-TUESDAY NIGHT...UPPER TROUGH MOVES THROUGH BRINGING ANOTHER COLD FRONT THROUGH THE AREA. DRIER AIR QUICKLY FOLLOWS BY LATE AFTERNOON/EARLY EVENING LEADING TO A CLEAR NIGHT. WILL KEEP SOME LOW POPS EAST OF THE CO/KS BORDER TUESDAY MORNING .LONG TERM (WEDNESDAY-SATURDAY)... NO CHANGES MADE AT THIS TIME. && .AVIATION... MVFR/IFR CLOUDS EXPECTED IN THE KGLD AND KMCK AREAS AROUND 14Z BEHIND A COLD FRONT WHOS WINDS WILL GUST INTO THE 40-45 KT RANGE THROUGH THE AFTERNOON. BETWEEN 18Z AND 21Z CLOUD HEIGHTS WILL RISE INTO THE MVFR RANGE AS THE STORM SYSTEM CONTINUES NORTHEAST. WINDS HOWEVER WILL REMAIN RATHER HIGH. BETWEEN 21Z-00Z EXPECT A RAPID CLEARING WITH LITTLE IF ANY CLOUDS BY 00Z. WINDS WILL SLOWLY SUBSIDE AND BY 00Z BE NEAR CALM BEFORE RETURNING FROM THE SOUTH AFTER 06Z. SHOWERY PRECIPITATION IS POSSIBLE AFTER 14Z...ENDING BY 21Z. && && && .GLD WATCHES/WARNINGS/ADVISORIES... KS...WIND ADVISORY UNTIL 4 PM MDT /5 PM CDT/ THIS AFTERNOON FOR KSZ001>004-013>016-028-029. NE...WIND ADVISORY UNTIL 4 PM MDT /5 PM CDT/ THIS AFTERNOON FOR NEZ079>081. CO...WIND ADVISORY UNTIL 4 PM MDT THIS AFTERNOON FOR COZ090-091. && $$ DDT/DDT ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SHREVEPORT LA 942 PM CDT MON OCT 1 2007 .DISCUSSION... VERY ISOLATED SHOWERS CONTINUE ACROSS EXTREME E TX/NW LA...AND PORTIONS OF SW AR THIS EVENING...WITH AR SHOWERS TIED TO AN 850MB DIFFERENTIAL MOISTURE BOUNDARY ASSOCIATED WITH A WEAK 850MB RIDGE CENTERED OVER CNTRL/S AR...AND REMAINING SFC BASED INSTABILITY...PER LATEST RUC/LAPS ANALYSIS. HOWEVER...SHOWER ACTIVITY WILL LIKELY DIMINISH ALL TOGETHER WITHIN THE NEXT HOUR OR TWO WITH FURTHER SFC STABILIZATION...AND CAN BE HANDLED IN NOWCASTS. OTHERWISE...CU FIELD SLOWLY MIGRATING W ACROSS NW LA/E TX/SW AR AROUND THE RIDGE...MAY TAKE MORE OF A TURN TO THE N LATE TONIGHT...WHEN 20-30 KT S LLJ GET CRANKING ACROSS OK/NCNTRL TX. AS HAS BEEN THE CASE THE LAST FEW NIGHTS...WILL ALSO SEE LOW CLOUDS DEVELOP MAINLY OVER E TX AROUND THE PERIPHERY THE THE SFC RIDGE AXIS EXTENDING FROM THE E COAST...SW THROUGH THE GULF COAST STATES AND INTO CNTRL LA. MAY ALSO SEE PATCHY DENSE FOG FORM AGAIN OVER DEEP E TX OVERNIGHT...AS THE SFC SETUP HAS REMAINED MUCH THE SAME...AND HAVE INSERTED THIS INTO THE ZONE UPDATE THIS EVENING. ALSO MAY SEE PATCHY DENSE FOG DEVELOP WHERE EARLIER COMPLEX OF STORMS RAINED THEMSELVES OUT OVER SCNTRL AR...INCLUDING NEVADA AND UNION COUNTIES. NOT BUYING INTO THE COOLER TEMPS MOS IS ADVERTISING ACROSS THE REGION TONIGHT...AND WILL PLAY THE PERSISTENCE GAME OVER SW AR/NW LA/E TX. NOTICIABLLY DRIER AIR TO THE E OVER MS MAY BACKBUILD A TAD W INTO OUR EXTREME E NCNTRL LA PARISHES...BUT FEEL THAT LOWER 60S FOR THESE AREAS WILL BE A STRETCH. THUS...HAVE RAISED MIN TEMPS ACROSS THE BOARD AT LEAST A CATEGORY...GIVEN NEUTRAL OR EVEN WEAK WARM ADVECTION/MIXING. UPDATE ALREADY OUT. 15 && .AVIATION... ISOLATED SHOWERS HAVE LINGERED THIS EVENING...BUT SHOULD DISSIPATE BY 04Z. OTHERWISE VFR FLIGHT CONDITIONS WITH THE EXCEPTION OF ELD. OVER 2 INCHES OF RAIN IN THE ELD AREA EARLIER TODAY AND LEFT THE GROUND SATURATED WHICH WAS RESULTING IN SHALLOW FOG. EXPECT IFR/LIFR VSBYS THROUGHOUT THE NIGHTTIME HOURS IN PORTIONS OF SOUTHCENTRAL AR WITH CONDITIONS NOT IMPROVING UNTIL AFT 14Z. 00Z SOUNDINGS INDICATED SOUTHERLY LOW LEVEL WINDS HAVE WEAKENED PAST 24 HRS...BUT LOW LEVEL MOISTURE STILL PLENTIFUL. EXPECTING LESS IFR CIGS AND VSBYS TUESDAY MORNING AREA WIDE...BUT STILL THINK THERE WILL BE VSBY RESTRICTIONS AS LOW AS LIFR AT LFK AND MAYBE OCH FROM FOG AFT 08Z...CONTINUING THROUGH 13Z. SUNRISE HAZE/FOG MAY BRING VSBYS DOWN MOST AREAS TO MVFR...INCLUDING SHV...TYR...GGG AND MLU. 00Z ISSUE OF TAFS INDICATES SOME IFR CIGS ACROSS EAST TEXAS AFT 09Z...BUT MAY BACK OFF ON THE 06Z ISSUE...GIVEN THE EASTERLY WINDS. CONVECTION...IF ANY TUESDAY...WILL BE ISOLATED AND NOT MENTIONED IN TAFS. SURFACE WINDS MOSTLY SOUTHERLY AND LESS THAN 10KTS. /14/ && .PRELIMINARY POINT TEMPS/POPS... SHV 73 91 66 91 / 10 10 10 10 MLU 66 91 61 91 / 0 10 10 10 DEQ 70 91 67 87 / 10 10 40 30 TXK 72 90 68 89 / 10 10 20 30 ELD 68 90 64 89 / 10 10 10 20 TYR 72 91 69 91 / 10 10 10 20 GGG 71 91 68 90 / 10 10 10 20 LFK 72 91 67 92 / 10 10 10 10 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...NONE. LA...NONE. OK...NONE. TX...NONE. && $$ 15/14 la AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 145 PM EDT MON OCT 1 2007 .DISCUSSION (ISSUED AT 1132 AM EDT)... THE MAIN CONCERN WITH THIS FORECAST UPDATE IS FOG AND PRECIPITATION POTENTIAL FOR THIS AFTERNOON. TODAY...WATER VAPOR IMAGERY AND RUC SHOWING A CLOSED LOW OVER SOUTHEAST WISCONSIN MOVING INTO SOUTH CENTRAL LOWER MICHIGAN THIS AFTERNOON. RIDGES ARE OVER NEW ENGLAND AND THE UPPER MISSISSIPPI RIVER VALLEY. A TROUGH IS ALSO OVER THE NORTHERN ROCKIES. SHORTWAVE ENERGY IS SWEEPING THROUGH CENTRAL AND EASTERN U.P. SURFACE RIDGE IS OVER ONTARIO PUSHING A COLD FRONT THROUGH EASTERN U.P. DEEP MOISTURE WILL SHIFT INTO LOWER MICHGIAN THIS AFTERNOON. THE SURFACE RH WILL REMAIN 90 PERCENT OR GREATER OVER THE U.P. THIS AFTERNOON AS THE MOISTURE IS TRAPPED UNDER A SURFACE INVERSION. CLOUD COVER WILL SLOW THE HEATING AND THE CURRENT GRIDDED TEMPERATURES STILL LOOK REASONABLE. TONIGHT AND LATER...UPPER LEVEL TROUGH OVER WESTERN MONTANA WILL CONTINUE ITS EASTWARD MARCH...REACHING THE WESTERN DAKOTAS BY 12Z TUE. THE COLD FRONT...CURRENTLY THE LEE TROUGH...ASSOCIATED WITH THE UPPER TROUGH SHOULD REACH GRAND FORKS AROUND THE SAME TIME. CLOSER TO HOME...THE UPPER TROUGH WILL CAUSE THE UPPER RIDGE TO BUILD UP INTO UPPER MICHIGAN...RESULTING IN A DRY NIGHT WITH SUBSIDENCE ALOFT. HOWEVER...THIS SUBSIDENCE AND DRYING ALOFT WITH LOW LEVEL MOISTURE TRAPPED AT THE SURFACE PRESENTS A CONCERN FOR FOG...ESPECIALLY WITH LIGHT WINDS THROUGH AT LEAST THE EARLY PORTION OF THE OVERNIGHT HOURS AS THE SURFACE RIDGE OVER THE PLAINS CROSSES. GUIDANCE ALONG WITH SOUNDINGS SHOW A VERY FAVORABLE SCENARIO FOR FOG...AND THUS HAVE INCREASED THE COVERAGE FURTHER TO GO WITH WIDESPREAD FOG AND AREAS OF DENSE FOG. NEXT SHIFT MAY NEED TO ISSUE A DENSE FOG ADVISORY. RETURN FLOW DEVELOPING TOWARDS SUNRISE OUT IN THE WESTERN U.P. MAY START TO BREAK UP THE FOG...PARTICULARLY IN DOWNSLOPE AREAS. LOW TEMPERATURES SHOULD REMAIN WARM WITH STRATUS AND FOG AROUND. TUE INTO TUE NIGHT...THE MAIN FOCUS WILL REMAIN ON THE IMPACTS OF THE UPPER LEVEL TROUGH AS IT MOVES EASTWARD TO THE MN/WI LINE AT 00Z WED AND TO EASTERN ONTARIO BY 12Z WED. THE RAPID PROGRESSION OF THIS FEATURE ONLY ALLOWS FOR A NARROW AXIS OF MOISTURE TO ADVECT UP AHEAD OF THE ASSOCIATED COLD FRONT...AS INDICATED BY 850MB THETA-E ADVECTION. THUS IT DOES NOT APPEAR ANY MORE THAT SHOWERS OR STORMS COULD FORM DOWNSTREAM OVER NORTHERN WI AND ALONG THE WI BORDER. TIMING OF THE FEATURE HAS SPED UP WITH THE 00Z GFS/12Z ECMWF...SHOWING THE COLD FRONT AND AXIS OF GREATEST 850MB THETA-E ADVECTION AND MOISTURE CONVERGENCE IN NW WI AND IWD AREA AT 18Z...OVER THE CENTRAL U.P. AT 00Z...AND EAST OF SAULT STE MARIE BY 06Z. THE UKMET AND NAM ARE A BIT SLOWER WITH THE TROUGH...THUS WILL NOT CLEAR PCPN OUT AS FAST AS THE GFS/ECMWF. CHANGES MAY BE REQUIRED OVER THE NEXT FEW SHIFTS AS THE EXACT TROUGH TIMING BECOMES MORE CERTAIN. GIVEN THE STRENGTH OF THE DYNAMICS AND WARM ADVECTION SHOWN WITH THE TROUGH (12 HR 500MB HEIGHT CHANGE OF 100-130 M AND 850MB WINDS OF 40 KT)...THINK IT IS REASONABLE TO CONTINUE WITH LIKELY POPS. SOME SUN IS POSSIBLE ON TUE AHEAD OF THE PCPN...BUT IT IS UNCERTAIN HOW LONG GIVEN THE TIMING DIFFERENCES. THE SLOWER NAM SOLUTION WOULD ALLOW HIGHS TO REACH NEAR 70 WHEREAS THE FASTER GFS MAY KEEPS HIGHS MORE IN THE MID 60S. PLAN ON GOING IN-BETWEEN THE TWO FOR NOW. WED AND THU...QUIET WEATHER WITH ABOVE NORMAL TEMPERATURES ARE EXPECTED DURING THIS PERIOD...DUE TO ZONAL FLOW ALOFT GRADUALLY BACKING SW BRINGING MILD DOWNSLOPED PACIFIC AIR INTO THE GREAT LAKES REGION. GFS SOUNDINGS AND ECMWF RH PROGS DEPICT VERY LITTLE IN THE WAY OF CLOUDS DURING THIS PERIOD TOO...EXCEPT ACROSS WESTERN LAKE SUPERIOR WED NIGHT AND THU WHERE SOME ISENTROPIC LIFT BEGINS AND CREATES A MID CLOUD DECK. GIVEN PLENTY OF SUN BOTH DAYS...DRY AIR...AND 850MB TEMPS RISING FROM 8C AT 18Z WED TO 12C AT 18Z THU SUPPORTS HIGHS IN THE UPPER 60S TO LOW 70S BOTH DAYS. S TO SW SURFACE WINDS BETWEEN HIGH PRESSURE PROGGED OVER THE MID-ATLANTIC AND LOW PRESSURE MOVING ACROSS MANITOBA TO HUDSON BAY WILL YIELD AN EXTRA COUPLE DEGREES FOR DOWNSLOPE AREAS. BY LATE THU...PRESSURES FALLING OVER THE PLAINS SHOULD CAUSE WINDS TO BACK MORE SOUTHEASTERLY...RESULTING IN SOME COOLING ON THE EAST SIDE OF THE KEWEENAW PENINSULA. THU NIGHT THROUGH SUN...MUCH OF THIS PERIOD WILL BE FOCUSED ON THE MECHANISM THAT CAUSES THE ZONAL FLOW OVER THE AREA ON WED TO BACK SW ON THU...A DEEP TROUGH DIGGING DOWN INTO THE WESTERN U.S.. THERE ARE TWO QUESTIONS WITH THE TROUGH...HOW DEEP IT WILL BE AND HOW QUICK IT PUSHES EASTWARD. ECMWF AND GFS RUNS SEEM TO BE CONSISTENT WITHIN THEMSELVES WITH TWO SCENARIOS. THE ECMWF ALLOWS THE TROUGH TO DIG DOWN INTO THE FOUR CORNERS AREA BY 00Z SUN...PUMPING UP A LARGE RIDGE DOWNSTREAM ACROSS THE EASTERN U.S.. IF THIS OCCURS...THE ECMWF DEPICTS A VERY WARM AND HUMID DAY ON SAT WITH BREEZY SOUTH WINDS...850MB TEMPS OF 16-18C AND 850MB DEWPOINTS AROUND 14C. THIS IS THEN FOLLOWED BY A POSSIBLE HEAVY RAIN EVENT ON SUN. ON THE OTHER SIDE OF THE COIN...THE GFS IS MORE PROGRESSIVE AND SHOWS THE BASE OF THE UPPER TROUGH (AN UPPER LOW) INTO THE OMAHA AREA BY 00Z SUN WHICH LIFTS UP INTO THE GREAT LAKES AREA ON SUN. IF THIS SOLUTION OCCURS...THE GFS WRAPS UP THE UPPER LOW SO MUCH AND HAS 850MB TEMPS DOWN TO -4C AT IWD BY 12Z ALONG WITH PLENTY OF QPF...SUGGESTING A POSSIBLE SNOWSTORM. BASED ON THE CANADIAN AND UKMET WHICH LOOK MORE LIKE THE ECMWF...THE GFS SOLUTION IS VERY MUCH AN OUTLIER...THOUGH SNOWSTORMS FOR THE FIRST WEEKEND OF OCTOBER ARE DEFINITELY NOT UNCOMMON HERE. IN ANY EVENT...EITHER SOLUTION SUGGESTS AN INTERESTING WEEKEND IS IN STORE...WITH POTENTIAL FOR RECORD HIGHS ALONG WITH HEAVY PCPN. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... THERE WILL BE SOME VERY LIMITED DRYING IN THE LOW LEVELS AT KCMX...MVFR CEILING WILL REMAIN THROUGH THE DAY. -SHRA HAVE MOVED EAST OF KSAW AT THIS TIME. A NORTH WIND AT KSAW CONTINUE TO BRING COLD AIR OFF OF LAKE SUPERIOR AT THE LOW LEVELS CREATING A SURFACE BASED INVERSION TRAPPING FOG AT THE SURFACE. ALSO INVOLVED WILL BE SOME UPSLOPE CONDITIONS WHICH WILL KEEP LOW CLOUDS OVER THE SITE THROUGH THE AFTERNOON. GUIDANCE SUGGEST A TEMPORARY RISING IN VISIBIILTY AS TEMPERATURES RISE A LITTLE REDUCING SURFACE RH A LITTLE. AS TEMPERATURES COOL THIS EVENING CONDITIONS WILL DETERIORATE RAPIDLY AT BOTH SITES...LOWERING CEILINGS AND VISIBILITY. GUIDANCE SHOWING SOME DRY AIR ADVECTING INTO THE AREA BY LATE MORNING ON TUESDAY WILL SUPPORT A GRADUAL IMPROVEMENT OF CONDITIONS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FCST ISSUANCE)... WINDS WILL DIMINISH THRU THE DAY TODAY AS LOW PRES OVER NE IA MOVES NE AND WEAKENS...DISSIPATING THIS EVENING. AS THE WINDS DIMINISH... WILL NEED TO WATCH FOR FOG DEVELOPMENT...ESPECIALLY TONIGHT. NEXT ACTIVE LOW PRES TROUGH WILL RACE E AND CROSS LAKE SUPERIOR TUE NIGHT. SRLY WINDS WILL AGAIN RAMP UP IN ADVANCE OF THIS TROUGH...AND IT`S NOT OUT OF THE QUESTION THAT A FEW GALE FORCE GUSTS COULD OCCUR OVER THE E HALF OF THE LAKE LATE TUE AFTN/EVENING. WINDS FOR THE REMAINDER OF THE FCST (WED THRU FRI) SHOULD GENERALLY BE IN THE 10 TO 20KT RANGE WITH AN OCCASIONAL PERIOD OF 15 TO 25KT. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ SYNOPSIS AND TODAY...DLG TONIGHT AND LATER DISCUSSION...AJ AVIATION...DLG MARINE...ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 740 AM EDT MON OCT 1 2007 UPDATED FOR AVIATION DISCUSSION .SYNOPSIS (ISSUED AT 412 AM EDT)... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED AN UPPER LEVEL TROUGH FROM NORTHERN ONTARIO INTO IOWA...WITH A 573 DAM LOW NEAR CEDAR RAPIDS IOWA. RIDGES ARE PRESENT ON EITHER SIDE OF THE TROUGH OVER THE EASTERN U.S. AND WESTERN PLAINS. FARTHER WEST...A MORE IMPRESSIVE UPPER LEVEL TROUGH CAN BE SEEN ALONG THE PACIFIC NW COASTLINE. ISENTROPIC LIFT DOWNSTREAM OF THE UPPER LOW...IN ADDITION TO UPPER LEVEL DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A 110 KT JET NEAR THUNDER BAY ONTARIO...IS SUPPORTING SHOWERS FROM EASTERN WI/LAKE MI UP INTO THE CENTRAL U.P.. WITH PLENTY OF CLOUDS OVER THE AREA AND DEWPOINTS IN THE MID TO UPPER 50S...TEMPERATURES ARE QUITE WARM...CLOSER TO AVERAGE HIGHS. TO THE WEST OF THE AREA... OBSERVATIONS AND SATELLITE IMAGERY DEPICT LOW CLOUDS ACROSS NORTHERN MN FLOWING IN BEHIND A COLD FRONT CROSSING WESTERN UPPER MICHIGAN. CMX AND IWD NOW HAVE LIFR CEILINGS WITH MVFR VISIBILITIES. 00Z INL SOUNDING SHOWED THIS WITH A SATURATED LAYER NEAR 875MB WHICH REPRESENTS THE COLD FRONTAL INVERSION. CLOUDS CLEAR OUT ACROSS WESTERN MN AND THE DAKOTAS WHERE A SURFACE RIDGE OF HIGH PRESSURE EXISTS WITH DEWPOINTS IN THE 30S. FARTHER WEST...LEE TROUGHING IS ALREADY DEVELOPING ALONG THE ROCKIES...WITH A 1005MB LOW CENTERED NEAR EDMONTON ALBERTA DOWNSTREAM OF THE PACIFIC NW TROUGH. NOTE: WE DID NOT BREAK THE ALL-TIME SEPTEMBER PCPN RECORD AT THE OFFICE. AT MIDNIGHT EST...THE TOTAL SEPTEMBER RAINFALL WAS 7.48 INCHES...ABOUT 0.12 OF AN INCH SHORT OF THE 7.60 INCH RECORD. HAD THE CURRENT SHOWERS BEEN A FEW HOURS EARLIER...WE PROBABLY WOULD HAVE BROKE IT. && .DISCUSSION (ISSUED AT 412 AM EDT)... MAIN FORECAST CONCERNS ARE FOG DEVELOPMENT TONIGHT AND PCPN FOR TUE/TUE NIGHT. TODAY...UPPER LEVEL TROUGH ALONG THE PACIFIC NW COASTLINE IS PROGGED TO MOVE INTO WESTERN MONTANA BY 00Z...FORCING RIDGING TO BUILD UP INTO THE NORTHERN PLAINS AND EVENTUALLY THE DULUTH AREA BY 00Z WITH 500MB HEIGHTS OF 580 DAM. THIS RIDGING WILL ALSO FORCE THE UPPER LOW OVER IOWA TO CONTINUE MOVING...THOUGH IT APPEARS MORE EAST THAN NORTHEAST AS EXPECTED YESTERDAY. BY 00Z...MOST OF THE MODELS HAVE THE LOW NEAR DETROIT. ALTHOUGH THE TRACK IS FARTHER SOUTH...VERY LITTLE CHANGES ARE NEEDED TO THE PCPN FORECAST. SHOWERS PRESENT OVER THE CENTRAL PORTION OF THE CWA SHOULD GRADUALLY MOVE EAST AND FALL APART AS THE UPPER LOW MOVES EAST AND FILLS...IN ADDITION TO THE JET STREAK OVER THUNDER BAY MOVING NE AWAY FROM THE AREA. LOW CLOUDS... LIKELY WITH CLOUD TOPS ONLY NEAR 3000 FT DUE TO SUBSIDENCE AND DRYING OCCURRING ALOFT...SHOULD FILL IN IN THE WAKE OF THE UPPER LOW. RECENT RAINFALL WILL HELP MATTERS TOO IN DEVELOPING THE LOW CLOUDS/FOG. THE LATE TIME OF YEAR WILL ALSO HELP IN PREVENTING THE LOW CLOUD DECK FROM MIXING OUT. IN ADDITION...WITH THE SURFACE COLD FRONT CROSSING THE CWA...NORTHERLY FLOW BEHIND IT SHOULD RESULT IN SOME FOG AND/OR UPSLOPE DRIZZLE OVER THE HIGHER TERRAIN OUT OF THE LOW CLOUD DECK. APPEARS THE DRIZZLE WILL BE MOSTLY CONFINED TO THE NORTH CENTRAL U.P. WHERE LOW LEVEL MOISTURE IS DEEPEST...THOUGH SOME DRIZZLE/FOG IS POSSIBLE THIS MORNING IN THE WESTERN U.P. HIGHER TERRAIN AS SURFACE OBS FROM IWD AND CMX INDICATE. GIVEN THE CLOUDS...EXPECT TEMPERATURES TO HAVE A HARD TIME CLIMBING MUCH TODAY. GENERALLY FOLLOWED MET/MAV GUIDANCE VALUES. TONIGHT...UPPER LEVEL TROUGH OVER WESTERN MONTANA WILL CONTINUE ITS EASTWARD MARCH...REACHING THE WESTERN DAKOTAS BY 12Z TUE. THE COLD FRONT...CURRENTLY THE LEE TROUGH...ASSOCIATED WITH THE UPPER TROUGH SHOULD REACH GRAND FORKS AROUND THE SAME TIME. CLOSER TO HOME...THE UPPER TROUGH WILL CAUSE THE UPPER RIDGE TO BUILD UP INTO UPPER MICHIGAN...RESULTING IN A DRY NIGHT WITH SUBSIDENCE ALOFT. HOWEVER...THIS SUBSIDENCE AND DRYING ALOFT WITH LOW LEVEL MOISTURE TRAPPED AT THE SURFACE PRESENTS A CONCERN FOR FOG...ESPECIALLY WITH LIGHT WINDS THROUGH AT LEAST THE EARLY PORTION OF THE OVERNIGHT HOURS AS THE SURFACE RIDGE OVER THE PLAINS CROSSES. GUIDANCE ALONG WITH SOUNDINGS SHOW A VERY FAVORABLE SCENARIO FOR FOG...AND THUS HAVE INCREASED THE COVERAGE FURTHER TO GO WITH WIDESPREAD FOG AND AREAS OF DENSE FOG. NEXT SHIFT MAY NEED TO ISSUE A DENSE FOG ADVISORY. RETURN FLOW DEVELOPING TOWARDS SUNRISE OUT IN THE WESTERN U.P. MAY START TO BREAK UP THE FOG...PARTICULARLY IN DOWNSLOPE AREAS. LOW TEMPERATURES SHOULD REMAIN WARM WITH STRATUS AND FOG AROUND. TUE INTO TUE NIGHT...THE MAIN FOCUS WILL REMAIN ON THE IMPACTS OF THE UPPER LEVEL TROUGH AS IT MOVES EASTWARD TO THE MN/WI LINE AT 00Z WED AND TO EASTERN ONTARIO BY 12Z WED. THE RAPID PROGRESSION OF THIS FEATURE ONLY ALLOWS FOR A NARROW AXIS OF MOISTURE TO ADVECT UP AHEAD OF THE ASSOCIATED COLD FRONT...AS INDICATED BY 850MB THETA-E ADVECTION. THUS IT DOES NOT APPEAR ANY MORE THAT SHOWERS OR STORMS COULD FORM DOWNSTREAM OVER NORTHERN WI AND ALONG THE WI BORDER. TIMING OF THE FEATURE HAS SPED UP WITH THE 00Z GFS/12Z ECMWF...SHOWING THE COLD FRONT AND AXIS OF GREATEST 850MB THETA-E ADVECTION AND MOISTURE CONVERGENCE IN NW WI AND IWD AREA AT 18Z...OVER THE CENTRAL U.P. AT 00Z...AND EAST OF SAULT STE MARIE BY 06Z. THE UKMET AND NAM ARE A BIT SLOWER WITH THE TROUGH...THUS WILL NOT CLEAR PCPN OUT AS FAST AS THE GFS/ECMWF. CHANGES MAY BE REQUIRED OVER THE NEXT FEW SHIFTS AS THE EXACT TROUGH TIMING BECOMES MORE CERTAIN. GIVEN THE STRENGTH OF THE DYNAMICS AND WARM ADVECTION SHOWN WITH THE TROUGH (12 HR 500MB HEIGHT CHANGE OF 100-130 M AND 850MB WINDS OF 40 KT)...THINK IT IS REASONABLE TO CONTINUE WITH LIKELY POPS. SOME SUN IS POSSIBLE ON TUE AHEAD OF THE PCPN...BUT IT IS UNCERTAIN HOW LONG GIVEN THE TIMING DIFFERENCES. THE SLOWER NAM SOLUTION WOULD ALLOW HIGHS TO REACH NEAR 70 WHEREAS THE FASTER GFS MAY KEEPS HIGHS MORE IN THE MID 60S. PLAN ON GOING IN-BETWEEN THE TWO FOR NOW. WED AND THU...QUIET WEATHER WITH ABOVE NORMAL TEMPERATURES ARE EXPECTED DURING THIS PERIOD...DUE TO ZONAL FLOW ALOFT GRADUALLY BACKING SW BRINGING MILD DOWNSLOPED PACIFIC AIR INTO THE GREAT LAKES REGION. GFS SOUNDINGS AND ECMWF RH PROGS DEPICT VERY LITTLE IN THE WAY OF CLOUDS DURING THIS PERIOD TOO...EXCEPT ACROSS WESTERN LAKE SUPERIOR WED NIGHT AND THU WHERE SOME ISENTROPIC LIFT BEGINS AND CREATES A MID CLOUD DECK. GIVEN PLENTY OF SUN BOTH DAYS...DRY AIR...AND 850MB TEMPS RISING FROM 8C AT 18Z WED TO 12C AT 18Z THU SUPPORTS HIGHS IN THE UPPER 60S TO LOW 70S BOTH DAYS. S TO SW SURFACE WINDS BETWEEN HIGH PRESSURE PROGGED OVER THE MID-ATLANTIC AND LOW PRESSURE MOVING ACROSS MANITOBA TO HUDSON BAY WILL YIELD AN EXTRA COUPLE DEGREES FOR DOWNSLOPE AREAS. BY LATE THU...PRESSURES FALLING OVER THE PLAINS SHOULD CAUSE WINDS TO BACK MORE SOUTHEASTERLY...RESULTING IN SOME COOLING ON THE EAST SIDE OF THE KEWEENAW PENINSULA. THU NIGHT THROUGH SUN...MUCH OF THIS PERIOD WILL BE FOCUSED ON THE MECHANISM THAT CAUSES THE ZONAL FLOW OVER THE AREA ON WED TO BACK SW ON THU...A DEEP TROUGH DIGGING DOWN INTO THE WESTERN U.S.. THERE ARE TWO QUESTIONS WITH THE TROUGH...HOW DEEP IT WILL BE AND HOW QUICK IT PUSHES EASTWARD. ECMWF AND GFS RUNS SEEM TO BE CONSISTENT WITHIN THEMSELVES WITH TWO SCENARIOS. THE ECMWF ALLOWS THE TROUGH TO DIG DOWN INTO THE FOUR CORNERS AREA BY 00Z SUN...PUMPING UP A LARGE RIDGE DOWNSTREAM ACROSS THE EASTERN U.S.. IF THIS OCCURS...THE ECMWF DEPICTS A VERY WARM AND HUMID DAY ON SAT WITH BREEZY SOUTH WINDS...850MB TEMPS OF 16-18C AND 850MB DEWPOINTS AROUND 14C. THIS IS THEN FOLLOWED BY A POSSIBLE HEAVY RAIN EVENT ON SUN. ON THE OTHER SIDE OF THE COIN...THE GFS IS MORE PROGRESSIVE AND SHOWS THE BASE OF THE UPPER TROUGH (AN UPPER LOW) INTO THE OMAHA AREA BY 00Z SUN WHICH LIFTS UP INTO THE GREAT LAKES AREA ON SUN. IF THIS SOLUTION OCCURS...THE GFS WRAPS UP THE UPPER LOW SO MUCH AND HAS 850MB TEMPS DOWN TO -4C AT IWD BY 12Z ALONG WITH PLENTY OF QPF...SUGGESTING A POSSIBLE SNOWSTORM. BASED ON THE CANADIAN AND UKMET WHICH LOOK MORE LIKE THE ECMWF...THE GFS SOLUTION IS VERY MUCH AN OUTLIER...THOUGH SNOWSTORMS FOR THE FIRST WEEKEND OF OCTOBER ARE DEFINITELY NOT UNCOMMON HERE. IN ANY EVENT...EITHER SOLUTION SUGGESTS AN INTERESTING WEEKEND IS IN STORE...WITH POTENTIAL FOR RECORD HIGHS ALONG WITH HEAVY PCPN. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... -SHRA/-DZ HAVE EDGED E OF KCMX IN THE LAST FEW HRS AND VIS AND CIGS HAVE IMPROVED TO VFR AND MVFR RESPECTIVELY. WHILE THERE WILL BE SOME VERY LIMITED DRYING AT KCMX...EXPECT MVFR CIGS TO BE THE RULE TODAY. MEANWHILE...-SHRA/-DZ WILL PROBABLY LINGER THRU THE ENTIRE MORNING AT KSAW AS PCPN SHIELD ASSOCIATED WITH DISTURBANCE OVER SRN WI/NRN IL ONLY DRIFTS EWD. ALTHOUGH LIGHT...DEVELOPING NRLY UPSLOPING WINDS WILL RESULT IN LOW CIGS THRU THE DAY AT KSAW WITH IFR CIGS PROBABLY ONLY RISING TO THE LOW END OF MVFR IN THE AFTN. WITHOUT ANY SIGNIFICANT ADVECTION OF DRIER AIR INTO THE AREA TODAY AND WITH WINDS BECOMING LIGHT/CALM THIS EVENING...VIS AND CIGS SHOULD CRASH AT KCMX/KSAW TO VLIFR MID TO LATE EVENING. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FCST ISSUANCE)... WINDS WILL DIMINISH THRU THE DAY TODAY AS LOW PRES OVER NE IA MOVES NE AND WEAKENS...DISSIPATING THIS EVENING. AS THE WINDS DIMINISH... WILL NEED TO WATCH FOR FOG DEVELOPMENT...ESPECIALLY TONIGHT. NEXT ACTIVE LOW PRES TROUGH WILL RACE E AND CROSS LAKE SUPERIOR TUE NIGHT. SRLY WINDS WILL AGAIN RAMP UP IN ADVANCE OF THIS TROUGH...AND IT`S NOT OUT OF THE QUESTION THAT A FEW GALE FORCE GUSTS COULD OCCUR OVER THE E HALF OF THE LAKE LATE TUE AFTN/EVENING. WINDS FOR THE REMAINDER OF THE FCST (WED THRU FRI) SHOULD GENERALLY BE IN THE 10 TO 20KT RANGE WITH AN OCCASIONAL PERIOD OF 15 TO 25KT. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 412 AM EDT MON OCT 1 2007 .SYNOPSIS... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED AN UPPER LEVEL TROUGH FROM NORTHERN ONTARIO INTO IOWA...WITH A 573 DAM LOW NEAR CEDAR RAPIDS IOWA. RIDGES ARE PRESENT ON EITHER SIDE OF THE TROUGH OVER THE EASTERN U.S. AND WESTERN PLAINS. FARTHER WEST...A MORE IMPRESSIVE UPPER LEVEL TROUGH CAN BE SEEN ALONG THE PACIFIC NW COASTLINE. ISENTROPIC LIFT DOWNSTREAM OF THE UPPER LOW...IN ADDITION TO UPPER LEVEL DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A 110 KT JET NEAR THUNDER BAY ONTARIO...IS SUPPORTING SHOWERS FROM EASTERN WI/LAKE MI UP INTO THE CENTRAL U.P.. WITH PLENTY OF CLOUDS OVER THE AREA AND DEWPOINTS IN THE MID TO UPPER 50S...TEMPERATURES ARE QUITE WARM...CLOSER TO AVERAGE HIGHS. TO THE WEST OF THE AREA... OBSERVATIONS AND SATELLITE IMAGERY DEPICT LOW CLOUDS ACROSS NORTHERN MN FLOWING IN BEHIND A COLD FRONT CROSSING WESTERN UPPER MICHIGAN. CMX AND IWD NOW HAVE LIFR CEILINGS WITH MVFR VISIBILITIES. 00Z INL SOUNDING SHOWED THIS WITH A SATURATED LAYER NEAR 875MB WHICH REPRESENTS THE COLD FRONTAL INVERSION. CLOUDS CLEAR OUT ACROSS WESTERN MN AND THE DAKOTAS WHERE A SURFACE RIDGE OF HIGH PRESSURE EXISTS WITH DEWPOINTS IN THE 30S. FARTHER WEST...LEE TROUGHING IS ALREADY DEVELOPING ALONG THE ROCKIES...WITH A 1005MB LOW CENTERED NEAR EDMONTON ALBERTA DOWNSTREAM OF THE PACIFIC NW TROUGH. NOTE: WE DID NOT BREAK THE ALL-TIME SEPTEMBER PCPN RECORD AT THE OFFICE. AT MIDNIGHT EST...THE TOTAL SEPTEMBER RAINFALL WAS 7.48 INCHES...ABOUT 0.12 OF AN INCH SHORT OF THE 7.60 INCH RECORD. HAD THE CURRENT SHOWERS BEEN A FEW HOURS EARLIER...WE PROBABLY WOULD HAVE BROKE IT. && .DISCUSSION... MAIN FORECAST CONCERNS ARE FOG DEVELOPMENT TONIGHT AND PCPN FOR TUE/TUE NIGHT. TODAY...UPPER LEVEL TROUGH ALONG THE PACIFIC NW COASTLINE IS PROGGED TO MOVE INTO WESTERN MONTANA BY 00Z...FORCING RIDGING TO BUILD UP INTO THE NORTHERN PLAINS AND EVENTUALLY THE DULUTH AREA BY 00Z WITH 500MB HEIGHTS OF 580 DAM. THIS RIDGING WILL ALSO FORCE THE UPPER LOW OVER IOWA TO CONTINUE MOVING...THOUGH IT APPEARS MORE EAST THAN NORTHEAST AS EXPECTED YESTERDAY. BY 00Z...MOST OF THE MODELS HAVE THE LOW NEAR DETROIT. ALTHOUGH THE TRACK IS FARTHER SOUTH...VERY LITTLE CHANGES ARE NEEDED TO THE PCPN FORECAST. SHOWERS PRESENT OVER THE CENTRAL PORTION OF THE CWA SHOULD GRADUALLY MOVE EAST AND FALL APART AS THE UPPER LOW MOVES EAST AND FILLS...IN ADDITION TO THE JET STREAK OVER THUNDER BAY MOVING NE AWAY FROM THE AREA. LOW CLOUDS... LIKELY WITH CLOUD TOPS ONLY NEAR 3000 FT DUE TO SUBSIDENCE AND DRYING OCCURRING ALOFT...SHOULD FILL IN IN THE WAKE OF THE UPPER LOW. RECENT RAINFALL WILL HELP MATTERS TOO IN DEVELOPING THE LOW CLOUDS/FOG. THE LATE TIME OF YEAR WILL ALSO HELP IN PREVENTING THE LOW CLOUD DECK FROM MIXING OUT. IN ADDITION...WITH THE SURFACE COLD FRONT CROSSING THE CWA...NORTHERLY FLOW BEHIND IT SHOULD RESULT IN SOME FOG AND/OR UPSLOPE DRIZZLE OVER THE HIGHER TERRAIN OUT OF THE LOW CLOUD DECK. APPEARS THE DRIZZLE WILL BE MOSTLY CONFINED TO THE NORTH CENTRAL U.P. WHERE LOW LEVEL MOISTURE IS DEEPEST...THOUGH SOME DRIZZLE/FOG IS POSSIBLE THIS MORNING IN THE WESTERN U.P. HIGHER TERRAIN AS SURFACE OBS FROM IWD AND CMX INDICATE. GIVEN THE CLOUDS...EXPECT TEMPERATURES TO HAVE A HARD TIME CLIMBING MUCH TODAY. GENERALLY FOLLOWED MET/MAV GUIDANCE VALUES. TONIGHT...UPPER LEVEL TROUGH OVER WESTERN MONTANA WILL CONTINUE ITS EASTWARD MARCH...REACHING THE WESTERN DAKOTAS BY 12Z TUE. THE COLD FRONT...CURRENTLY THE LEE TROUGH...ASSOCIATED WITH THE UPPER TROUGH SHOULD REACH GRAND FORKS AROUND THE SAME TIME. CLOSER TO HOME...THE UPPER TROUGH WILL CAUSE THE UPPER RIDGE TO BUILD UP INTO UPPER MICHIGAN...RESULTING IN A DRY NIGHT WITH SUBSIDENCE ALOFT. HOWEVER...THIS SUBSIDENCE AND DRYING ALOFT WITH LOW LEVEL MOISTURE TRAPPED AT THE SURFACE PRESENTS A CONCERN FOR FOG...ESPECIALLY WITH LIGHT WINDS THROUGH AT LEAST THE EARLY PORTION OF THE OVERNIGHT HOURS AS THE SURFACE RIDGE OVER THE PLAINS CROSSES. GUIDANCE ALONG WITH SOUNDINGS SHOW A VERY FAVORABLE SCENARIO FOR FOG...AND THUS HAVE INCREASED THE COVERAGE FURTHER TO GO WITH WIDESPREAD FOG AND AREAS OF DENSE FOG. NEXT SHIFT MAY NEED TO ISSUE A DENSE FOG ADVISORY. RETURN FLOW DEVELOPING TOWARDS SUNRISE OUT IN THE WESTERN U.P. MAY START TO BREAK UP THE FOG...PARTICULARLY IN DOWNSLOPE AREAS. LOW TEMPERATURES SHOULD REMAIN WARM WITH STRATUS AND FOG AROUND. TUE INTO TUE NIGHT...THE MAIN FOCUS WILL REMAIN ON THE IMPACTS OF THE UPPER LEVEL TROUGH AS IT MOVES EASTWARD TO THE MN/WI LINE AT 00Z WED AND TO EASTERN ONTARIO BY 12Z WED. THE RAPID PROGRESSION OF THIS FEATURE ONLY ALLOWS FOR A NARROW AXIS OF MOISTURE TO ADVECT UP AHEAD OF THE ASSOCIATED COLD FRONT...AS INDICATED BY 850MB THETA-E ADVECTION. THUS IT DOES NOT APPEAR ANY MORE THAT SHOWERS OR STORMS COULD FORM DOWNSTREAM OVER NORTHERN WI AND ALONG THE WI BORDER. TIMING OF THE FEATURE HAS SPED UP WITH THE 00Z GFS/12Z ECMWF...SHOWING THE COLD FRONT AND AXIS OF GREATEST 850MB THETA-E ADVECTION AND MOISTURE CONVERGENCE IN NW WI AND IWD AREA AT 18Z...OVER THE CENTRAL U.P. AT 00Z...AND EAST OF SAULT STE MARIE BY 06Z. THE UKMET AND NAM ARE A BIT SLOWER WITH THE TROUGH...THUS WILL NOT CLEAR PCPN OUT AS FAST AS THE GFS/ECMWF. CHANGES MAY BE REQUIRED OVER THE NEXT FEW SHIFTS AS THE EXACT TROUGH TIMING BECOMES MORE CERTAIN. GIVEN THE STRENGTH OF THE DYNAMICS AND WARM ADVECTION SHOWN WITH THE TROUGH (12 HR 500MB HEIGHT CHANGE OF 100-130 M AND 850MB WINDS OF 40 KT)...THINK IT IS REASONABLE TO CONTINUE WITH LIKELY POPS. SOME SUN IS POSSIBLE ON TUE AHEAD OF THE PCPN...BUT IT IS UNCERTAIN HOW LONG GIVEN THE TIMING DIFFERENCES. THE SLOWER NAM SOLUTION WOULD ALLOW HIGHS TO REACH NEAR 70 WHEREAS THE FASTER GFS MAY KEEPS HIGHS MORE IN THE MID 60S. PLAN ON GOING IN-BETWEEN THE TWO FOR NOW. WED AND THU...QUIET WEATHER WITH ABOVE NORMAL TEMPERATURES ARE EXPECTED DURING THIS PERIOD...DUE TO ZONAL FLOW ALOFT GRADUALLY BACKING SW BRINGING MILD DOWNSLOPED PACIFIC AIR INTO THE GREAT LAKES REGION. GFS SOUNDINGS AND ECMWF RH PROGS DEPICT VERY LITTLE IN THE WAY OF CLOUDS DURING THIS PERIOD TOO...EXCEPT ACROSS WESTERN LAKE SUPERIOR WED NIGHT AND THU WHERE SOME ISENTROPIC LIFT BEGINS AND CREATES A MID CLOUD DECK. GIVEN PLENTY OF SUN BOTH DAYS...DRY AIR...AND 850MB TEMPS RISING FROM 8C AT 18Z WED TO 12C AT 18Z THU SUPPORTS HIGHS IN THE UPPER 60S TO LOW 70S BOTH DAYS. S TO SW SURFACE WINDS BETWEEN HIGH PRESSURE PROGGED OVER THE MID-ATLANTIC AND LOW PRESSURE MOVING ACROSS MANITOBA TO HUDSON BAY WILL YIELD AN EXTRA COUPLE DEGREES FOR DOWNSLOPE AREAS. BY LATE THU...PRESSURES FALLING OVER THE PLAINS SHOULD CAUSE WINDS TO BACK MORE SOUTHEASTERLY...RESULTING IN SOME COOLING ON THE EAST SIDE OF THE KEWEENAW PENINSULA. THU NIGHT THROUGH SUN...MUCH OF THIS PERIOD WILL BE FOCUSED ON THE MECHANISM THAT CAUSES THE ZONAL FLOW OVER THE AREA ON WED TO BACK SW ON THU...A DEEP TROUGH DIGGING DOWN INTO THE WESTERN U.S.. THERE ARE TWO QUESTIONS WITH THE TROUGH...HOW DEEP IT WILL BE AND HOW QUICK IT PUSHES EASTWARD. ECMWF AND GFS RUNS SEEM TO BE CONSISTENT WITHIN THEMSELVES WITH TWO SCENARIOS. THE ECMWF ALLOWS THE TROUGH TO DIG DOWN INTO THE FOUR CORNERS AREA BY 00Z SUN...PUMPING UP A LARGE RIDGE DOWNSTREAM ACROSS THE EASTERN U.S.. IF THIS OCCURS...THE ECMWF DEPICTS A VERY WARM AND HUMID DAY ON SAT WITH BREEZY SOUTH WINDS...850MB TEMPS OF 16-18C AND 850MB DEWPOINTS AROUND 14C. THIS IS THEN FOLLOWED BY A POSSIBLE HEAVY RAIN EVENT ON SUN. ON THE OTHER SIDE OF THE COIN...THE GFS IS MORE PROGRESSIVE AND SHOWS THE BASE OF THE UPPER TROUGH (AN UPPER LOW) INTO THE OMAHA AREA BY 00Z SUN WHICH LIFTS UP INTO THE GREAT LAKES AREA ON SUN. IF THIS SOLUTION OCCURS...THE GFS WRAPS UP THE UPPER LOW SO MUCH AND HAS 850MB TEMPS DOWN TO -4C AT IWD BY 12Z ALONG WITH PLENTY OF QPF...SUGGESTING A POSSIBLE SNOWSTORM. BASED ON THE CANADIAN AND UKMET WHICH LOOK MORE LIKE THE ECMWF...THE GFS SOLUTION IS VERY MUCH AN OUTLIER...THOUGH SNOWSTORMS FOR THE FIRST WEEKEND OF OCTOBER ARE DEFINITELY NOT UNCOMMON HERE. IN ANY EVENT...EITHER SOLUTION SUGGESTS AN INTERESTING WEEKEND IS IN STORE...WITH POTENTIAL FOR RECORD HIGHS ALONG WITH HEAVY PCPN. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... SHOWERS ARE EXPECTED ACROSS CENTRAL UPPER MICHIGAN OVERNIGHT AS A LOW PRESSURE SYSTEM OVER IOWA MOVES INTO NORTHERN IL. STEADIER RAINFALL WILL EVENTUALLY LOWER CIGS/VSBYS INTO THE MVFR RANGE AND THEN TO IFR CONDITIONS LATE IN THE NIGHT INTO THE MORNING. ALTHOUGH THE LOW AND PRECIP SHIELD SLIDES TO THE EAST...CIGS WILL ONLY GRADUALLY IMPROVE MONDAY AS SFC-850 MB MOISTURE REMAINS IN PLACE FOR MOST OF THE DAY. THE LOWEST CIGS ARE EXPECTED AT KSAW WITH NE WINDS PROVIDING MORE DIRECT UPSLOPE FLOW. EXPECT LOW CLOUDS/FOG TO REDEVELOP THIS EVENING AS THE LOW LEVEL MOISTURE REMAINS IN PLACE AND WEAK ERLY SURFACE FLOW DEVELOPS AT KCMX AND E TO NE FLOW CONTINUES AT KSAW. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FCST ISSUANCE)... WINDS WILL DIMINISH THRU THE DAY TODAY AS LOW PRES OVER NE IA MOVES NE AND WEAKENS...DISSIPATING THIS EVENING. AS THE WINDS DIMINISH... WILL NEED TO WATCH FOR FOG DEVELOPMENT...ESPECIALLY TONIGHT. NEXT ACTIVE LOW PRES TROUGH WILL RACE E AND CROSS LAKE SUPERIOR TUE NIGHT. SRLY WINDS WILL AGAIN RAMP UP IN ADVANCE OF THIS TROUGH...AND IT`S NOT OUT OF THE QUESTION THAT A FEW GALE FORCE GUSTS COULD OCCUR OVER THE E HALF OF THE LAKE LATE TUE AFTN/EVENING. WINDS FOR THE REMAINDER OF THE FCST (WED THRU FRI) SHOULD GENERALLY BE IN THE 10 TO 20KT RANGE WITH AN OCCASIONAL PERIOD OF 15 TO 25KT. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...JLB MARINE...ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 126 AM EDT MON OCT 1 2007 UPDATED FOR AVIATION DISCUSSION .UPDATE (ISSUED AT 1030 PM EDT)... RADAR SHOWED A LARGE AREA OF SHOWERS AND SCATTERED THUNDERSTORMS FROM SW TO N CNTRL WI AND INTO CNTRL UPPER MI. THE PCPN CLOSER TO UPPER MI WAS SUPPORTED BY STRONG 600-500 FGEN AHEAD OF THE CLOSED 500 MB LOW OVER IA AND UPPER LEVEL DIV WITH THE RIGHT ENTRANCE OF A 110-120 KT 250 MB JET N OF LAKE SUPERIOR. SATELLITE/RADAR TRENDS AND THE 00Z NAM AND RUC SUGGEST THAT THE PCPN OVER NRN WI WILL CONTINUE TO SPREAD MORE NNE IN RESPONSE TO THE UPPER LEVEL DYNAMICS COMPARED TO THE EARLIER BATCH OF PCPN INTO CNTRL UPPER MI THAT WAS MOVING MORE TO THE ENE. SO...HIGHEST POPS/COVERAGE WILL CONTINUE OVER CNTRL AND SE UPPER MI WITH ONLY SCT/CHANCE POPS OVER THE WEST. OVERALL RAINFALL AMOUNTS ARE NOT EXPECTED TO BE EXCESSIVE...PER UPSTREAM REPORTS OVER WI...WITH GENERALLY 0.25-0.50 INCH AMOUNTS AND ONLY LCL AMOUNTS AOA 1.00 INCH. && .SYNOPSIS... WATER VAPOR IMAGERY AND RUC/NAM SHOWING A CLOSED LOW OVER EASTERN NEBRASKA MOVING EAST INTO A RIDGE OVER WESTERN QUEBEC. A LONGWAVE TROUGH IS JUST OFF THE PACIFIC NORTHWEST. OTHER WEAK SHORTWAVES ARE OVER NORTHERN MINNESOTA...OVER SOUTHEAST MANITOBA...OVER AND CENTRAL ONTARIO. SURFACE ANALYSIS DEPICTS A LARGE OVER NEW ENGLAND WITH ACCOMPANYING RIDGE BLANKETING THE EAST COAST AND THE SOUTHEASTERN STATES. A FRONTAL SYSTEM EXTENDS FROM A LOW OVER NORTHWEST ONTARIO SOUTHWEST THROUGH NORTHEAST MINNESOTA TO A LOW OVER KOMA AREA. AN UPPER LEVEL 100+ KNOT JET MAX IS OVER THE NORTHWEST SHORE OF LAKE SUPERIOR...FOLLOWED BY ANOTHER OVER NORTHWEST MISSOURI. THESE ARE DRAWING DEEP MOISTURE FROM THE GULF INTO THE NORTHERN MISSISSIPPI RIVER VALLEY AND WESTERN END OF THE FORECAST AREA. SHOWERS AND THUNDERSTORMS ARE OCCURRING OVER WESTERN PART OF THE CWA AND OVER CENTRAL ONTARIO IN THE AREA OF HIGHEST MOISTURE AND UPPER LEVEL DIVERGENCE. SCATTERED THUNDERSTORMS ARE FIRING ALONG AN 850MB THETA-E RIDGE AXIS AND BENEATH THE UPPER LEVEL DIVERGENCE ZONE OVER THE WESTERN U.P. AND NORTHERN WISCONSIN. && .SHORT TERM (TONIGHT AND MON)... MAIN FORECAST CONCERNS WITH THIS FORECAST IS THE CHANCE OF SHOWERS AND THUNDERSTORMS TONIGHT AND MONDAY. UPPER RIDGING WILL REBUILD ACROSS THE PLAINS AS THE EAST PACIFIC NW TROUGH MOVES INTO WASHINGTON AND OREGON STATE. THIS REBUILDING OF THE UPPER RIDGE WILL FORCE THE UPPER LOW NEAR OMAHA TO LIFT NORTHEAST AS IT RUNS INTO THE RIDGE TO ITS EAST. BY SUNRISE MONDAY...THE LOW SHOULD BE LOCATED NEAR GREEN BAY. DEEP MOISTURE FEEDING INTO THE FORECAST ALONG WITH THE UPPER LEVEL DIVERGENCE AND SHORTWAVE ENERGY SUPPORTS KEEPING CATEGORICAL POPS OVER THE WEST HALF OF THE CWA. FOR THE EASTERN CWA...HAVE ONLY WENT WITH LIKELY VALUES AS HEIGHT FALLS ARE LATEST TO HIT THERE. HIGH PRECIPITABLE WATER VALUES...AROUND 1.5 INCHES COULD SUPPORT SOME HEAVY RAINFALL AMOUNTS. GIVEN PLENTY OF CLOUD COVER AND HIGH DEWPOINTS SUGGESTS A WARM NIGHT...PROBABLY NOT TOO FAR FROM AVERAGE HIGH TEMPERATURES. THE RIDGE AXIS OVER THE PLAINS WILL SHIFT INTO WESTERN WISCONSIN ON MONDAY AS THE WESTERN TROUGH CONTINUES TO MOVE EASTWARD. THIS WILL CAUSE THE UPPER LOW TO SHIFT TO LAKE HURON. DNVA ASSOCIATED WITH THE RIDGE AXIS SHOULD ALLOW SHOWERS TO END BY 18Z OVER THE WEST HALF OF THE CWA AND OVER MUCH OF THE EAST HALF OF THE CWA BY 00Z. AS DRY AIR MOVES WILL LOWER POPS OVER THE FAR WESTERN U.P. IN THE MORNING AND WILL MAINTAIN THE IDEA OF LIKELY POPS OVER THE EASTERN CWA WITH CHANCE POPS ELSEWHERE. ALTHOUGH THE SHOWERS END...DRYING ALOFT ASSOCIATED WITH THE UPPER RIDGE APPEARS TO SET UP A SUBSIDENCE INVERSION. GIVEN THE TIME OF YEAR AND PLENTY OF MOISTURE FROM THE RAIN TONIGHT SUGGESTS THE POSSIBILITY OF A LOW STRATUS DECK GETTING STUCK OVER MUCH OF THE U.P.. WINDS TURNING NORTH ON THE BACK SIDE OF A SURFACE LOW ASSOCIATED WITH THE UPPER LOW COULD ALSO RESULT IN SOME MIST AND OR DRIZZLE OVER UPSLOPE AREAS. GIVEN ALL THE CLOUD COVER...TEMPERATURES WILL NOT RISE MUCH. .LONG TERM (MON NIGHT THROUGH NEXT SUN)... AMPLIFIED UPR LEVEL PATTERN BECOMES MORE ZONAL BY MID WEEK THEN THE AMPLITUDE INCREASES SUBSTANTIALLY AGAIN BY LATE WEEK. IN GENERAL THE UPR LEVEL FLOW INTO UPR LAKES IS FM WEST/SOUTHWEST...SO ABOVE NORMAL TEMPS CONTINUE UNTIL NEXT WEEKEND. SHORTWAVE RIDGING DEVELOPING IN WAKE OF MON SYSTEM QUICKLY GIVES WAY TO THE KICKER SHORTWAVE TROUGH CURRENTLY DIVING TOWARD CA COAST. THIS TROUGH EMERGES ACROSS THE ROCKIES ON MON AND PUSHES INTO THE PLAINS MON NIGHT. STRONG SW FLOW AHEAD OF THE TROUGH WILL BE ENHANCED AS UPR JET OVR NORTHERN ROCKIES COMBINES WITH PIECE OF SUBTROPICAL JET ENERGY LIFTING OUT OF DESERT SW. THE STRONG JETS JUST AHEAD OF TROUGH SHOULD ALSO SERVE TO KEEP TROUGH POSITIVELY TILTED AND MOVING QUICKLY THROUGH THE REGION. AS IS THE CASE WITH THE SYSTEM AFFECTING THE AREA ATTM...THIS SYSTEM WILL ALSO BRING A STRONG SURGE OF ABOVE NORMAL MOISTURE INTO THE UPR LAKES THANKS TO INCREASING H85 WINDS. AXIS OF H85 DEWPOINTS TO +12C NOSES INTO SW CWA TUE MORNING THEN QUICKLY OVERTAKES REST OF CWA BY TUE EVENING. COMBINATION OF HEIGHT FALLS AND PERIOD OF UPPER LEVEL DIVERGENCE SHOULD LEAD TO PERIOD OF MODERATE RAIN SPREADING FM WEST TO EAST ACROSS CWA. K INDEX VALUES ABOVE 30 AND PWATS ABOVE 1.5 INCHES ALSO LEAD TO POTENTIAL FOR HEAVY DOWNPOURS IN THE STRONGEST CONVECTIVE ELEMENTS. CORFIDI VECTORS INDICATE THAT MOST ACTIVITY WILL KEEP TRUCKING TO THE NE SO UNLESS CELLS BEGIN TO TRAIN DO NOT FORSEE A FLOODING THREAT. MODELS CONTINUE TO TREND QUICKER WITH EXIT OF THE TROUGH AND ANY PCPN. TRIMMED BACK POPS OVERNIGHT TUE NIGHT. AFTER THE SHORTWAVE TROUGH EXITS THE REGION ON WED...A BROAD TROUGH DEVELOPS OFFSHORE THE PACIFIC NORTHWEST. THIS LEADS TO STRONG 250MB JET ENERGY STREAMING ACROSS NORTHERN PARTS OF THE ROCKIES INTO THE NORTH CENTRAL CONUS AND TO EASTERN CANADA. THIS WILL KEEP THE PRIMARY SFC FRONT ALONG THE US/CANADIAN BORDER AND SHOULD KEEP PCPN OUT OF THE AREA UNTIL FRI. TROUGH SHIFTS INTO THE CONUS BY SAT AND THIS SHOULD GRADUALLY PUSH THE FRONT TOWARD UPR LAKES. INCREASING MOISTURE AND STRONG LOW LEVEL WINDS LEAD TO INCREASED CHANCES OF PCPN FRI INTO SAT. MAIN FRONT SLIDES THROUGH REGION LATE SAT SO PCPN CHANCES SHOULD WANE INTO SUN. MUCH COOLER TEMPS SUN/MON IN WAKE OF THE FRONT. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... SHOWERS ARE EXPECTED ACROSS CENTRAL UPPER MICHIGAN OVERNIGHT AS A LOW PRESSURE SYSTEM OVER IOWA MOVES INTO NORTHERN IL. STEADIER RAINFALL WILL EVENTUALLY LOWER CIGS/VSBYS INTO THE MVFR RANGE AND THEN TO IFR CONDITIONS LATE IN THE NIGHT INTO THE MORNING. ALTHOUGH THE LOW AND PRECIP SHIELD SLIDES TO THE EAST...CIGS WILL ONLY GRADUALLY IMPROVE MONDAY AS SFC-850 MB MOISTURE REMAINS IN PLACE FOR MOST OF THE DAY. THE LOWEST CIGS ARE EXPECTED AT KSAW WITH NE WINDS PROVIDING MORE DIRECT UPSLOPE FLOW. EXPECT LOW CLOUDS/FOG TO REDEVELOP THIS EVENING AS THE LOW LEVEL MOISTURE REMAINS IN PLACE AND WEAK ERLY SURFACE FLOW DEVELOPS AT KCMX AND E TO NE FLOW CONTINUES AT KSAW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FCST ISSUANCE)... A COLD FRONT WILL MOVE THROUGH LAKE SUPERIOR TONIGHT. WINDS BEHIND THE FRONT WILL VEER WEST AND NORTHWEST. WINDS WILL INCREASE TO 15 TO 25 KTS OVER THE EAST HALF OF THE LAKE AHEAD OF THE FRONT WHICH IS FAVORED FOR STRONGER WINDS IN SOUTHERLY FLOW REGIMES. THE AREA AROUND GRAND MARAIS AT THE EAST END OF PICTURED ROCKS NATIONAL LAKESHORE IS ONE LOCATION THAT WILL SEE THE HIGHEST WINDS. WINDS WILL DIMINISH TONIGHT AND ESPECIALLY ON MONDAY AS WEAKENING LOW PRES MOVES TO THE UPPER GREAT LAKES REGION. THERE WILL BE SOME FOG DEVELOPMENT OVER MAIN THE EAST END TONIGHT AS THE WINDS DIMINISH. NEXT ACTIVE LOW PRES TROUGH WILL RACE EAST AND CROSS LAKE SUPERIOR TUESDAY NIGHT. SOUTHERLY WINDS WILL AGAIN WRAP UP IN ADVANCE OF THIS TROUGH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ UPDATE...JLB SHORT TERM...DLG LONG TERM...JLA MARINE...DLG AVIATION...JLB mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1030 PM EDT SUN SEP 30 2007 .UPDATE... RADAR SHOWED A LARGE AREA OF SHOWERS AND SCATTERED THUNDERSTORMS FROM SW TO N CNTRL WI AND INTO CNTRL UPPER MI. THE PCPN CLOSER TO UPPER MI WAS SUPPORTED BY STRONG 600-500 FGEN AHEAD OF THE CLOSED 500 MB LOW OVER IA AND UPPER LEVEL DIV WITH THE RIGHT ENTRANCE OF A 110-120 KT 250 MB JET N OF LAKE SUPERIOR. SATELLITE/RADAR TRENDS AND THE 00Z NAM AND RUC SUGGEST THAT THE PCPN OVER NRN WI WILL CONTINUE TO SPREAD MORE NNE IN RESPONSE TO THE UPPER LEVEL DYNAMICS COMPARED TO THE EARLIER BATCH OF PCPN INTO CNTRL UPPER MI THAT WAS MOVING MORE TO THE ENE. SO...HIGHEST POPS/COVERAGE WILL CONTINUE OVER CNTRL AND SE UPPER MI WITH ONLY SCT/CHANCE POPS OVER THE WEST. OVERALL RAINFALL AMOUNTS ARE NOT EXPECTED TO BE EXCESSIVE...PER UPSTREAM REPORTS OVER WI...WITH GENERALLY 0.25-0.50 INCH AMOUNTS AND ONLY LCL AMOUNTS AOA 1.00 INCH. GRIDS AND ZFP WERE ADJUSTED ACCORDINGLY. .SYNOPSIS... WATER VAPOR IMAGERY AND RUC/NAM SHOWING A CLOSED LOW OVER EASTERN NEBRASKA MOVING EAST INTO A RIDGE OVER WESTERN QUEBEC. A LONGWAVE TROUGH IS JUST OFF THE PACIFIC NORTHWEST. OTHER WEAK SHORTWAVES ARE OVER NORTHERN MINNESOTA...OVER SOUTHEAST MANITOBA...OVER AND CENTRAL ONTARIO. SURFACE ANALYSIS DEPICTS A LARGE OVER NEW ENGLAND WITH ACCOMPANYING RIDGE BLANKETING THE EAST COAST AND THE SOUTHEASTERN STATES. A FRONTAL SYSTEM EXTENDS FROM A LOW OVER NORTHWEST ONTARIO SOUTHWEST THROUGH NORTHEAST MINNESOTA TO A LOW OVER KOMA AREA. AN UPPER LEVEL 100+ KNOT JET MAX IS OVER THE NORTHWEST SHORE OF LAKE SUPERIOR...FOLLOWED BY ANOTHER OVER NORTHWEST MISSOURI. THESE ARE DRAWING DEEP MOISTURE FROM THE GULF INTO THE NORTHERN MISSISSIPPI RIVER VALLEY AND WESTERN END OF THE FORECAST AREA. SHOWERS AND THUNDERSTORMS ARE OCCURRING OVER WESTERN PART OF THE CWA AND OVER CENTRAL ONTARIO IN THE AREA OF HIGHEST MOISTURE AND UPPER LEVEL DIVERGENCE. SCATTERED THUNDERSTORMS ARE FIRING ALONG AN 850MB THETA-E RIDGE AXIS AND BENEATH THE UPPER LEVEL DIVERGENCE ZONE OVER THE WESTERN U.P. AND NORTHERN WISCONSIN. && .SHORT TERM (TONIGHT AND MON)... MAIN FORECAST CONCERNS WITH THIS FORECAST IS THE CHANCE OF SHOWERS AND THUNDERSTORMS TONIGHT AND MONDAY. UPPER RIDGING WILL REBUILD ACROSS THE PLAINS AS THE EAST PACIFIC NW TROUGH MOVES INTO WASHINGTON AND OREGON STATE. THIS REBUILDING OF THE UPPER RIDGE WILL FORCE THE UPPER LOW NEAR OMAHA TO LIFT NORTHEAST AS IT RUNS INTO THE RIDGE TO ITS EAST. BY SUNRISE MONDAY...THE LOW SHOULD BE LOCATED NEAR GREEN BAY. DEEP MOISTURE FEEDING INTO THE FORECAST ALONG WITH THE UPPER LEVEL DIVERGENCE AND SHORTWAVE ENERGY SUPPORTS KEEPING CATEGORICAL POPS OVER THE WEST HALF OF THE CWA. FOR THE EASTERN CWA...HAVE ONLY WENT WITH LIKELY VALUES AS HEIGHT FALLS ARE LATEST TO HIT THERE. HIGH PRECIPITABLE WATER VALUES...AROUND 1.5 INCHES COULD SUPPORT SOME HEAVY RAINFALL AMOUNTS. GIVEN PLENTY OF CLOUD COVER AND HIGH DEWPOINTS SUGGESTS A WARM NIGHT...PROBABLY NOT TOO FAR FROM AVERAGE HIGH TEMPERATURES. THE RIDGE AXIS OVER THE PLAINS WILL SHIFT INTO WESTERN WISCONSIN ON MONDAY AS THE WESTERN TROUGH CONTINUES TO MOVE EASTWARD. THIS WILL CAUSE THE UPPER LOW TO SHIFT TO LAKE HURON. DNVA ASSOCIATED WITH THE RIDGE AXIS SHOULD ALLOW SHOWERS TO END BY 18Z OVER THE WEST HALF OF THE CWA AND OVER MUCH OF THE EAST HALF OF THE CWA BY 00Z. AS DRY AIR MOVES WILL LOWER POPS OVER THE FAR WESTERN U.P. IN THE MORNING AND WILL MAINTAIN THE IDEA OF LIKELY POPS OVER THE EASTERN CWA WITH CHANCE POPS ELSEWHERE. ALTHOUGH THE SHOWERS END...DRYING ALOFT ASSOCIATED WITH THE UPPER RIDGE APPEARS TO SET UP A SUBSIDENCE INVERSION. GIVEN THE TIME OF YEAR AND PLENTY OF MOISTURE FROM THE RAIN TONIGHT SUGGESTS THE POSSIBILITY OF A LOW STRATUS DECK GETTING STUCK OVER MUCH OF THE U.P.. WINDS TURNING NORTH ON THE BACK SIDE OF A SURFACE LOW ASSOCIATED WITH THE UPPER LOW COULD ALSO RESULT IN SOME MIST AND OR DRIZZLE OVER UPSLOPE AREAS. GIVEN ALL THE CLOUD COVER...TEMPERATURES WILL NOT RISE MUCH. .LONG TERM (MON NIGHT THROUGH NEXT SUN)... AMPLIFIED UPR LEVEL PATTERN BECOMES MORE ZONAL BY MID WEEK THEN THE AMPLITUDE INCREASES SUBSTANTIALLY AGAIN BY LATE WEEK. IN GENERAL THE UPR LEVEL FLOW INTO UPR LAKES IS FM WEST/SOUTHWEST...SO ABOVE NORMAL TEMPS CONTINUE UNTIL NEXT WEEKEND. SHORTWAVE RIDGING DEVELOPING IN WAKE OF MON SYSTEM QUICKLY GIVES WAY TO THE KICKER SHORTWAVE TROUGH CURRENTLY DIVING TOWARD CA COAST. THIS TROUGH EMERGES ACROSS THE ROCKIES ON MON AND PUSHES INTO THE PLAINS MON NIGHT. STRONG SW FLOW AHEAD OF THE TROUGH WILL BE ENHANCED AS UPR JET OVR NORTHERN ROCKIES COMBINES WITH PIECE OF SUBTROPICAL JET ENERGY LIFTING OUT OF DESERT SW. THE STRONG JETS JUST AHEAD OF TROUGH SHOULD ALSO SERVE TO KEEP TROUGH POSITIVELY TILTED AND MOVING QUICKLY THROUGH THE REGION. AS IS THE CASE WITH THE SYSTEM AFFECTING THE AREA ATTM...THIS SYSTEM WILL ALSO BRING A STRONG SURGE OF ABOVE NORMAL MOISTURE INTO THE UPR LAKES THANKS TO INCREASING H85 WINDS. AXIS OF H85 DEWPOINTS TO +12C NOSES INTO SW CWA TUE MORNING THEN QUICKLY OVERTAKES REST OF CWA BY TUE EVENING. COMBINATION OF HEIGHT FALLS AND PERIOD OF UPPER LEVEL DIVERGENCE SHOULD LEAD TO PERIOD OF MODERATE RAIN SPREADING FM WEST TO EAST ACROSS CWA. K INDEX VALUES ABOVE 30 AND PWATS ABOVE 1.5 INCHES ALSO LEAD TO POTENTIAL FOR HEAVY DOWNPOURS IN THE STRONGEST CONVECTIVE ELEMENTS. CORFIDI VECTORS INDICATE THAT MOST ACTIVITY WILL KEEP TRUCKING TO THE NE SO UNLESS CELLS BEGIN TO TRAIN DO NOT FORSEE A FLOODING THREAT. MODELS CONTINUE TO TREND QUICKER WITH EXIT OF THE TROUGH AND ANY PCPN. TRIMMED BACK POPS OVERNIGHT TUE NIGHT. AFTER THE SHORTWAVE TROUGH EXITS THE REGION ON WED...A BROAD TROUGH DEVELOPS OFFSHORE THE PACIFIC NORTHWEST. THIS LEADS TO STRONG 250MB JET ENERGY STREAMING ACROSS NORTHERN PARTS OF THE ROCKIES INTO THE NORTH CENTRAL CONUS AND TO EASTERN CANADA. THIS WILL KEEP THE PRIMARY SFC FRONT ALONG THE US/CANADIAN BORDER AND SHOULD KEEP PCPN OUT OF THE AREA UNTIL FRI. TROUGH SHIFTS INTO THE CONUS BY SAT AND THIS SHOULD GRADUALLY PUSH THE FRONT TOWARD UPR LAKES. INCREASING MOISTURE AND STRONG LOW LEVEL WINDS LEAD TO INCREASED CHANCES OF PCPN FRI INTO SAT. MAIN FRONT SLIDES THROUGH REGION LATE SAT SO PCPN CHANCES SHOULD WANE INTO SUN. MUCH COOLER TEMPS SUN/MON IN WAKE OF THE FRONT. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... SHOWERS ARE EXPECTED ACROSS THE WEST HALF OF UPPER MICHIGAN THIS EVENING CONTINUING OVERNIGHT OVER CENTRAL UPPER MICHIGAN AS A LOW PRESSURE SYSTEM OVER WESTERN IOWA MOVES INTO SOUTHERN WISCONSIN. STEADIER RAINFALL WILL EVENTUALLY LOWER CIGS/VSBYS INTO THE MVFR RANGE THIS EVENING AND TO IFR CONDITIONS LATE TONIGHT INTO MON MORNING. ALTHOUGH THE RAIN WILL END CIGS WILL ONLY GRADUALLY IMPROVE MONDAY AS SFC-850 MB MOISTURE REMAINS IN PLACE FOR MOST OF THE DAY. THE LOWEST CIGS ARE EXPECTED AT KSAW WITH NE WINDS PROVIDING MORE DIRECT UPSLOPE FLOW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FCST ISSUANCE)... A COLD FRONT WILL MOVE THROUGH LAKE SUPERIOR TONIGHT. WINDS BEHIND THE FRONT WILL VEER WEST AND NORTHWEST. WINDS WILL INCREASE TO 15 TO 25 KTS OVER THE EAST HALF OF THE LAKE AHEAD OF THE FRONT WHICH IS FAVORED FOR STRONGER WINDS IN SOUTHERLY FLOW REGIMES. THE AREA AROUND GRAND MARAIS AT THE EAST END OF PICTURED ROCKS NATIONAL LAKESHORE IS ONE LOCATION THAT WILL SEE THE HIGHEST WINDS. WINDS WILL DIMINISH TONIGHT AND ESPECIALLY ON MONDAY AS WEAKENING LOW PRES MOVES TO THE UPPER GREAT LAKES REGION. THERE WILL BE SOME FOG DEVELOPMENT OVER MAIN THE EAST END TONIGHT AS THE WINDS DIMINISH. NEXT ACTIVE LOW PRES TROUGH WILL RACE EAST AND CROSS LAKE SUPERIOR TUESDAY NIGHT. SOUTHERLY WINDS WILL AGAIN WRAP UP IN ADVANCE OF THIS TROUGH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ SHORT TERM...DLG LONG TERM...JLA AVIATION/MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 745 PM EDT SUN SEP 30 2007 .SYNOPSIS... WATER VAPOR IMAGERY AND RUC/NAM SHOWING A CLOSED LOW OVER EASTERN NEBRASKA MOVING EAST INTO A RIDGE OVER WESTERN QUEBEC. A LONGWAVE TROUGH IS JUST OFF THE PACIFIC NORTHWEST. OTHER WEAK SHORTWAVES ARE OVER NORTHERN MINNESOTA...OVER SOUTHEAST MANITOBA...OVER AND CENTRAL ONTARIO. SURFACE ANALYSIS DEPICTS A LARGE OVER NEW ENGLAND WITH ACCOMPANYING RIDGE BLANKETING THE EAST COAST AND THE SOUTHEASTERN STATES. A FRONTAL SYSTEM EXTENDS FROM A LOW OVER NORTHWEST ONTARIO SOUTHWEST THROUGH NORTHEAST MINNESOTA TO A LOW OVER KOMA AREA. AN UPPER LEVEL 100+ KNOT JET MAX IS OVER THE NORTHWEST SHORE OF LAKE SUPERIOR...FOLLOWED BY ANOTHER OVER NORTHWEST MISSOURI. THESE ARE DRAWING DEEP MOISTURE FROM THE GULF INTO THE NORTHERN MISSISSIPPI RIVER VALLEY AND WESTERN END OF THE FORECAST AREA. SHOWERS AND THUNDERSTORMS ARE OCCURRING OVER WESTERN PART OF THE CWA AND OVER CENTRAL ONTARIO IN THE AREA OF HIGHEST MOISTURE AND UPPER LEVEL DIVERGENCE. SCATTERED THUNDERSTORMS ARE FIRING ALONG AN 850MB THETA-E RIDGE AXIS AND BENEATH THE UPPER LEVEL DIVERGENCE ZONE OVER THE WESTERN U.P. AND NORTHERN WISCONSIN. && .SHORT TERM (TONIGHT AND MON)... MAIN FORECAST CONCERNS WITH THIS FORECAST IS THE CHANCE OF SHOWERS AND THUNDERSTORMS TONIGHT AND MONDAY. UPPER RIDGING WILL REBUILD ACROSS THE PLAINS AS THE EAST PACIFIC NW TROUGH MOVES INTO WASHINGTON AND OREGON STATE. THIS REBUILDING OF THE UPPER RIDGE WILL FORCE THE UPPER LOW NEAR OMAHA TO LIFT NORTHEAST AS IT RUNS INTO THE RIDGE TO ITS EAST. BY SUNRISE MONDAY...THE LOW SHOULD BE LOCATED NEAR GREEN BAY. DEEP MOISTURE FEEDING INTO THE FORECAST ALONG WITH THE UPPER LEVEL DIVERGENCE AND SHORTWAVE ENERGY SUPPORTS KEEPING CATEGORICAL POPS OVER THE WEST HALF OF THE CWA. FOR THE EASTERN CWA...HAVE ONLY WENT WITH LIKELY VALUES AS HEIGHT FALLS ARE LATEST TO HIT THERE. HIGH PRECIPITABLE WATER VALUES...AROUND 1.5 INCHES COULD SUPPORT SOME HEAVY RAINFALL AMOUNTS. GIVEN PLENTY OF CLOUD COVER AND HIGH DEWPOINTS SUGGESTS A WARM NIGHT...PROBABLY NOT TOO FAR FROM AVERAGE HIGH TEMPERATURES. THE RIDGE AXIS OVER THE PLAINS WILL SHIFT INTO WESTERN WISCONSIN ON MONDAY AS THE WESTERN TROUGH CONTINUES TO MOVE EASTWARD. THIS WILL CAUSE THE UPPER LOW TO SHIFT TO LAKE HURON. DNVA ASSOCIATED WITH THE RIDGE AXIS SHOULD ALLOW SHOWERS TO END BY 18Z OVER THE WEST HALF OF THE CWA AND OVER MUCH OF THE EAST HALF OF THE CWA BY 00Z. AS DRY AIR MOVES WILL LOWER POPS OVER THE FAR WESTERN U.P. IN THE MORNING AND WILL MAINTAIN THE IDEA OF LIKELY POPS OVER THE EASTERN CWA WITH CHANCE POPS ELSEWHERE. ALTHOUGH THE SHOWERS END...DRYING ALOFT ASSOCIATED WITH THE UPPER RIDGE APPEARS TO SET UP A SUBSIDENCE INVERSION. GIVEN THE TIME OF YEAR AND PLENTY OF MOISTURE FROM THE RAIN TONIGHT SUGGESTS THE POSSIBILITY OF A LOW STRATUS DECK GETTING STUCK OVER MUCH OF THE U.P.. WINDS TURNING NORTH ON THE BACK SIDE OF A SURFACE LOW ASSOCIATED WITH THE UPPER LOW COULD ALSO RESULT IN SOME MIST AND OR DRIZZLE OVER UPSLOPE AREAS. GIVEN ALL THE CLOUD COVER...TEMPERATURES WILL NOT RISE MUCH. .LONG TERM (MON NIGHT THROUGH NEXT SUN)... AMPLIFIED UPR LEVEL PATTERN BECOMES MORE ZONAL BY MID WEEK THEN THE AMPLITUDE INCREASES SUBSTANTIALLY AGAIN BY LATE WEEK. IN GENERAL THE UPR LEVEL FLOW INTO UPR LAKES IS FM WEST/SOUTHWEST...SO ABOVE NORMAL TEMPS CONTINUE UNTIL NEXT WEEKEND. SHORTWAVE RIDGING DEVELOPING IN WAKE OF MON SYSTEM QUICKLY GIVES WAY TO THE KICKER SHORTWAVE TROUGH CURRENTLY DIVING TOWARD CA COAST. THIS TROUGH EMERGES ACROSS THE ROCKIES ON MON AND PUSHES INTO THE PLAINS MON NIGHT. STRONG SW FLOW AHEAD OF THE TROUGH WILL BE ENHANCED AS UPR JET OVR NORTHERN ROCKIES COMBINES WITH PIECE OF SUBTROPICAL JET ENERGY LIFTING OUT OF DESERT SW. THE STRONG JETS JUST AHEAD OF TROUGH SHOULD ALSO SERVE TO KEEP TROUGH POSITIVELY TILTED AND MOVING QUICKLY THROUGH THE REGION. AS IS THE CASE WITH THE SYSTEM AFFECTING THE AREA ATTM...THIS SYSTEM WILL ALSO BRING A STRONG SURGE OF ABOVE NORMAL MOISTURE INTO THE UPR LAKES THANKS TO INCREASING H85 WINDS. AXIS OF H85 DEWPOINTS TO +12C NOSES INTO SW CWA TUE MORNING THEN QUICKLY OVERTAKES REST OF CWA BY TUE EVENING. COMBINATION OF HEIGHT FALLS AND PERIOD OF UPPER LEVEL DIVERGENCE SHOULD LEAD TO PERIOD OF MODERATE RAIN SPREADING FM WEST TO EAST ACROSS CWA. K INDEX VALUES ABOVE 30 AND PWATS ABOVE 1.5 INCHES ALSO LEAD TO POTENTIAL FOR HEAVY DOWNPOURS IN THE STRONGEST CONVECTIVE ELEMENTS. CORFIDI VECTORS INDICATE THAT MOST ACTIVITY WILL KEEP TRUCKING TO THE NE SO UNLESS CELLS BEGIN TO TRAIN DO NOT FORSEE A FLOODING THREAT. MODELS CONTINUE TO TREND QUICKER WITH EXIT OF THE TROUGH AND ANY PCPN. TRIMMED BACK POPS OVERNIGHT TUE NIGHT. AFTER THE SHORTWAVE TROUGH EXITS THE REGION ON WED...A BROAD TROUGH DEVELOPS OFFSHORE THE PACIFIC NORTHWEST. THIS LEADS TO STRONG 250MB JET ENERGY STREAMING ACROSS NORTHERN PARTS OF THE ROCKIES INTO THE NORTH CENTRAL CONUS AND TO EASTERN CANADA. THIS WILL KEEP THE PRIMARY SFC FRONT ALONG THE US/CANADIAN BORDER AND SHOULD KEEP PCPN OUT OF THE AREA UNTIL FRI. TROUGH SHIFTS INTO THE CONUS BY SAT AND THIS SHOULD GRADUALLY PUSH THE FRONT TOWARD UPR LAKES. INCREASING MOISTURE AND STRONG LOW LEVEL WINDS LEAD TO INCREASED CHANCES OF PCPN FRI INTO SAT. MAIN FRONT SLIDES THROUGH REGION LATE SAT SO PCPN CHANCES SHOULD WANE INTO SUN. MUCH COOLER TEMPS SUN/MON IN WAKE OF THE FRONT. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... SHOWERS ARE EXPECTED ACROSS THE WEST HALF OF UPPER MICHIGAN THIS EVENING CONTINUING OVERNIGHT OVER CENTRAL UPPER MICHIGAN AS A LOW PRESSURE SYSTEM OVER WESTERN IOWA MOVES INTO SOUTHERN WISCONSIN. STEADIER RAINFALL WILL EVENTUALLY LOWER CIGS/VSBYS INTO THE MVFR RANGE THIS EVENING AND TO IFR CONDITIONS LATE TONIGHT INTO MON MORNING. ALTHOUGH THE RAIN WILL END CIGS WILL ONLY GRADUALLY IMPROVE MONDAY AS SFC-850 MB MOISTURE REMAINS IN PLACE FOR MOST OF THE DAY. THE LOWEST CIGS ARE EXPECTED AT KSAW WITH NE WINDS PROVIDING MORE DIRECT UPSLOPE FLOW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FCST ISSUANCE)... A COLD FRONT WILL MOVE THROUGH LAKE SUPERIOR TONIGHT. WINDS BEHIND THE FRONT WILL VEER WEST AND NORTHWEST. WINDS WILL INCREASE TO 15 TO 25 KTS OVER THE EAST HALF OF THE LAKE AHEAD OF THE FRONT WHICH IS FAVORED FOR STRONGER WINDS IN SOUTHERLY FLOW REGIMES. THE AREA AROUND GRAND MARAIS AT THE EAST END OF PICTURED ROCKS NATIONAL LAKESHORE IS ONE LOCATION THAT WILL SEE THE HIGHEST WINDS. WINDS WILL DIMINISH TONIGHT AND ESPECIALLY ON MONDAY AS WEAKENING LOW PRES MOVES TO THE UPPER GREAT LAKES REGION. THERE WILL BE SOME FOG DEVELOPMENT OVER MAIN THE EAST END TONIGHT AS THE WINDS DIMINISH. NEXT ACTIVE LOW PRES TROUGH WILL RACE EAST AND CROSS LAKE SUPERIOR TUESDAY NIGHT. SOUTHERLY WINDS WILL AGAIN WRAP UP IN ADVANCE OF THIS TROUGH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ SHORT TERM...DLG LONG TERM...JLA AVIATION/MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 133 PM EDT SUN SEP 30 2007 ...UPDATED FOR AVIATION... .DISCUSSION... MANY FORECAST CONCERNS WITH THIS FORECAST UPDATE IS THE CHANCE OF PRECIPITATION THIS AFTERNOON. WATER VAPOR IMAGERY AND RUC/NAM SHOWING A DEEP LOW OVER WESTERN KANSAS MOVING NORTHEAST INTO THE RIDGE OVER WESTERN QUEBEC. A LONGWAVE TROUGH IS JUST OFF THE PACIFIC NORTHWEST. OTHER WEAK SHORTWAVES ARE OVER NORTHERN MINNESOTA AND OVER MANITOBA. A PAIR OF LARGE HIGH BLANKETS MUCH OF THE SOUTHERN MISSISSIPPI RIVER VALLEY AND OVER NEW ENGLAND. A FRONTAL SYSTEM EXTENDS FROM A LOW OVER NORTHWEST ONTARIO SOUTHWEST THROUGH NORTHWEST MINNESOTA TO A LOW OVER NORTHEAST NEBRASKA. AN UPPER LEVEL 100+ KNOT JET MAX IS OVER CENTRAL ONTARIO...FOLLOWED BY ANOTHER OVER CENTRAL KANSAS. THIS IS DRAWING DEEP MOISTURE FROM THE GULF INTO THE NORTHERN MISSISSIPPI RIVER VALLEY AND WESTERN END OF THE FORECAST AREA. SHOWERS AND THUNDERSTORMS ARE OCCURRING OVER WESTERN PART OF THE CWA AND OVER CENTRAL ONTARIO IN THE AREA OF HIGHEST MOISTURE AND UPPER LEVEL DIVERGENCE. THE KANSAS LOW WILL MOVE INTO EASTERN NEBRASKA BY LATE AFTERNOON. THE RIDGE OVER WESTERN QUEBEC WILL CONTINUE. A WEAK SHORTWAVE WILL PUSH ACROSS THE WESTERN U.P. DEEP MOISTURE CONTINUES TO REMAIN OVER ONTARIO...MINNESOTA...NORTHWEST WISCONSIN...AND WEST END OF CWA. KMQT 88D AND SURFACE REPORTS INDICATE THAT MOST OF THE RAIN IS COMING FROM HIGH BASED CLOUDS. THUS PLAN TO KEEP RAIN IN THE FORECAST FOR THE AFTERNOON OVER THE WEST AND MOSTLY CLOUDY OVER THE CENTRAL PART WITH MAINLY AC. WINDS WILL REMAIN OUT OF THE SOUTH. SOME OF THE LOW LEVEL JET WILL MIX TO THE SURFACE AS GUSTY CONDITIONS AS INDICATED BY SEVERAL STATIONS ALONG THE LAKE SHORE. PLAN TO UPDATE THE FORECAST TO TWEAK THE WORDING. EXTENDED... TONIGHT...UPPER RIDGING WILL REBUILD ACROSS THE PLAINS AS THE EAST PACIFIC NW TROUGH MOVES INTO WASHINGTON AND OREGON STATE. THIS REBUILDING OF THE UPPER RIDGE WILL FORCE THE UPPER LOW NEAR OMAHA TO LIFT NE AS IT RUNS INTO THE RIDGE TO ITS EAST. BY 12Z MON...THE LOW SHOULD BE LOCATED NEAR APPLETON WI. MORE IMPRESSIVE HEIGHT FALLS COMPARED TO TODAY...ALONG WITH SOME MID-LEVEL FRONTOGENESIS OVER THE WESTERN U.P...SHOULD SUPPORT AN EXPANSION AND INTENSIFICATION OF PCPN OVER THE CWA. WILL RAISE POPS TO CATEGORICAL OVER THE WEST HALF OF THE CWA GIVEN CONSISTENT MODEL AGREEMENT FOR PCPN THERE. FOR THE EASTERN CWA...HAVE ONLY WENT WITH LIKELY VALUES AS HEIGHT FALLS ARE LATEST TO HIT THERE. HIGH PRECIPITABLE WATER VALUES...AROUND 1.5 INCHES OR 250 PERCENT OF NORMAL...COULD SUPPORT SOME HEAVY RAINFALL AMOUNTS. THE NAM INDICATES THIS WITH 3.1 INCHES AT IWD BETWEEN 00-12Z. GIVEN PLENTY OF CLOUD COVER AND HIGH DEWPOINTS SUGGESTS A WARM NIGHT...PROBABLY NOT TOO FAR FROM AVERAGE HIGH TEMPERATURES. MON...RIDGE AXIS OVER THE PLAINS WILL SHIFT INTO WESTERN WI BY 00Z AS THE WESTERN TROUGH CONTINUES TO PLOW EASTWARD. THIS WILL CAUSE THE UPPER LOW TO SHIFT TO NEAR LAKE HURON. DNVA ASSOCIATED WITH THE RIDGE AXIS SHOULD ALLOW SHOWERS TO END BY 18Z OVER THE WEST HALF OF THE CWA AND OVER MUCH OF THE EAST HALF OF THE CWA BY 00Z. WILL MAINTAIN THE IDEA OF LIKELY POPS OVER THE EASTERN CWA IN THE MORNING WITH CHANCE POPS ELSEWHERE. ALTHOUGH THE SHOWERS END...DRYING ALOFT ASSOCIATED WITH THE UPPER RIDGE APPEARS TO SET UP A SUBSIDENCE INVERSION. GIVEN THE TIME OF YEAR AND PLENTY OF MOISTURE FROM THE RAIN TONIGHT SUGGESTS THE POSSIBILITY OF A LOW STRATUS DECK GETTING STUCK OVER MUCH OF THE U.P.. WINDS TURNING NORTH ON THE BACK SIDE OF A SURFACE LOW ASSOCIATED WITH THE UPPER LOW COULD ALSO RESULT IN SOME MIST AND OR DRIZZLE OVER UPSLOPE AREAS. GIVEN ALL THE CLOUD COVER... TEMPERATURES WILL NOT RISE MUCH. MON NIGHT...UPPER RIDGE AXIS MOVES ACROSS THE CWA DURING THE NIGHT WHILE THE WESTERN TROUGH MOVES OUT INTO THE WESTERN PLAINS. SUBSIDENCE UNDER THE RIDGE SHOULD EFFECTIVELY END ANY PCPN IN THE EVENING...WHICH WOULD BE LOCATED IN THE FAR EASTERN PORTION OF THE CWA. STILL...CLOUDS ARE EXPECTED TO LINGER WITH MOISTURE TRAPPED UNDER THE SUBSIDENCE INVERSION. DRYING ABOVE THE INVERSION AND LIGHT WINDS SHOULD SUPPORT FOG DEVELOPMENT OVER LAND...AND PERHAPS ON THE GREAT LAKES TOO. HAVE INCREASED THE COVERAGE TO AREAS OF FOG. IF ANY CLEARING CAN DEVELOP IN THE LOW STRATUS DECK...DENSE FOG DEVELOPING IS NOT OUT OF THE QUESTION. GIVEN CLOUD COVER AND MOISTURE...HAVE STAYED ABOVE THE COLDER MET GUIDANCE WITH READINGS CLOSER TO MAV GUIDANCE. TUE INTO TUE NIGHT...THE BREAK IN PCPN OBSERVED MON NIGHT WILL BE BRIEF AS THE UPPER TROUGH OVER THE WESTERN PLAINS MOVES EAST AT A GOOD CLIP. STRONG DPVA FROM HEIGHT FALLS MOVING ACROSS WARM ADVECTION AT THE LOW LEVELS (ANOTHER 50-60 KT JET AT 850MB PROGGED) SUGGESTS A LINE OF SHOWERS AND THUNDERSTORMS SHOULD FORM IN THE VICINITY OF THE TROUGHS ASSOCIATED SURFACE COLD FRONT. IN ADDITION...STRONG 850MB THETA-E ADVECTION AHEAD OF THE TROUGH MOVING ACROSS WESTERN UPPER MICHIGAN IN THE MORNING COULD SUPPORT SOME SHOWERS AND THUNDERSTORMS (SIMILAR TO TODAY). MODEL RUN-TO-RUN AND BETWEEN MODEL CONSISTENCY IS REMARKABLY GREAT WITH THIS SYSTEM...AND THUS HAVE INCREASED POPS TO LIKELY WITH THE COLD FRONTAL THUNDERSTORMS. VERY STRONG WIND FIELDS ASSOCIATED WITH THE SYSTEM WOULD SUGGEST A SEVERE THREAT...HOWEVER IT APPEARS THERE IS VERY LITTLE CAPE AVAILABLE. SPC DAY 3 OUTLOOK HAS AREA ONLY IN 5 PERCENT AT THIS TIME...AND GIVEN THE LACK OF A SIGNIFICANT AMOUNT OF CAPE...HAVE DECLINED TO MENTION ANY SEVERE POSSIBILITY IN THE HWO. IF MORE SUN CAN OCCUR ON TUE...THEN THE POTENTIAL FOR SEVERE WEATHER WOULD GO UP. MAIN CONCERN WOULD BE HEAVY RAIN GIVEN THAT ANOTHER SURGE OF 1.5-1.75 INCH PRECIPITABLE WATER VALUES ARE PROGGED WITH THE FRONT. CLEARING IS EXPECTED TO FOLLOW BEHIND THE COLD FRONT AND UPPER TROUGH AS PRECIPITABLE WATER VALUES FALL TO 0.5 INCHES ACROSS THE ENTIRE CWA BY 12Z WED. THIS COOLER AND DRY AIR BUT BREEZY WEST TO NORTHWEST WINDS SHOULD RESULT IN READINGS SIMILAR TO THOSE MON NIGHT. WED THROUGH SUN...FLOW TURNS ZONAL WED...WITH WESTERLY FLOW HELPING TO BRING MILD PACIFIC AIR INTO THE AREA. THEN FOR THU THROUGH SAT...ANOTHER SIGNIFICANT TROUGH IS EXPECTED TO DROP SOUTH THROUGH THE WESTERN STATES...HEADING OUT INTO THE PLAINS ON SAT. THE RESULT IS THE DEVELOPMENT OF A LOW PRESSURE SYSTEM OVER THE DAKOTAS. WARM AIR ADVECTION AHEAD OF THE SYSTEM SHOULD HELP KEEP TEMPERATURES WELL ABOVE NORMAL. GFS/ECMWF BOTH DEPICT 850MB TEMPS CLIMBING TO 14-16C. BY SAT...WE COULD BE TALKING ABOUT ANOTHER DAY OF HUMID CONDITIONS AS PRECIPITABLE WATER VALUES INCREASE TO 1.5 TO 1.75 INCHES AHEAD OF THE APPROACHING TROUGH/COLD FRONT. UPPER TROUGH CROSSING THE AREA SAT NIGHT WILL BRING IN MUCH COOLER CONDITIONS ON SUN...ASSUMING THE TROUGH CAN PUSH EAST INTO THE RIDGE THAT HAS BEEN BUILT OUT AHEAD OF IT. WILL NEED TO WATCH THIS SCENARIO CLOSELY AS THE PATTERN COULD BECOME FAVORABLE FOR VERY HEAVY RAIN. NOTE: WE NEED 0.28 INCHES OF PCPN AT THE OFFICE BY 05Z TONIGHT TO BREAK THE ALL TIME WETTEST SEPTEMBER RECORD. PREVIOUS RECORD IS 7.60 SET IN 1968. && .AVIATION (FOR THE 18 TAF ISSUANCE)... THE SHORTWAVE MOVING THROUGH NORTHERN MINNESOTA ANS WESTERN LAKE SUPERIOR CONTINUES TO CAUSE LOW CEILIGS AND SCATTERED RAIN SHOWERS AND THUNDERSTORMS OVER LAKE SUPERIOR. IR SATELLITE SHOWING SCATTERED THUNDERSTORMS MOVING INTO WEST U.P. THE MID LEVEL LOW WILL MOVE FROM EASTERN NEBRASKA EAST ACROSS THE LAKE MICHIGAN AND LOWER MICHIGAN. SCATTERED SHOWERS ARE MOVING INTO WESTERN GOGEBIC COUNTY ALONG A 850MB THETA-E RIDGE. THIS RIDGE IS EXPECTED SHIFT NORTHEAST ALONG THE LAKE SHORE AND SHOULD GENERATE A FEW SHOWERS AND THUNDERSTORMS. THIS RIDGE WILL SHIFT SOUTHEAST REACHING KSAW BY 00Z. THIS WILL CAUSE LOWER CEILING. A LOW LEVEL JET WILL BE OVER THE AREA THIS AFTERNOON ADDING TO THE GUSTY CONDITIONS AT KCMX AND KSAW. THE RAIN ACROSS THE AREA WILL LEAVE ENOUGH LOW LEVEL MOISTURE TO DEVELOP SOME DRIZZLE AND FOG OVER NIGHT AT BOTH LOCATION UNDER A SURFACE BASED INVERSION. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FCST ISSUANCE)... S WINDS...GENERALLY IN THE 15 TO 25 KT RANGE...WILL CONTINUE TODAY AHEAD OF A LOW PRES TROUGH OVER THE PLAINS. EXPECT FREQUENT GUSTS TO 30KT OVER THE E HALF OF THE LAKE WHICH IS FAVORED FOR STRONGER WINDS IN SRLY FLOW REGIMES. MAY SEE A FEW 35KT GALE FORCE GUSTS AS WELL. THE AREA AROUND GRAND MARAIS AT THE E END OF PICTURED ROCKS NATIONAL LAKESHORE IS ONE LOCATION THAT MAY SEE THE HIGHEST WINDS. WINDS WILL DIMINISH TONIGHT AND ESPECIALLY MON AS WEAKENING LOW PRES MOVES TO THE UPPER GREAT LAKES REGION. WILL NEED TO WATCH FOR FOG DEVELOPMENT AS THE WINDS DIMINISH. NEXT ACTIVE LOW PRES TROUGH WILL RACE E AND CROSS LAKE SUPERIOR TUE NIGHT. SRLY WINDS WILL AGAIN RAMP UP IN ADVANCE OF THIS TROUGH...AND IT`S NOT OUT OF THE QUESTION THAT A FEW GALE FORCE GUSTS COULD OCCUR OVER THE E HALF OF THE LAKE LATE TUE AFTN/EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ SYNOPSIS/FIRST PERIOD...DLG EXTENDED DISCUSSION...AJ AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1125 AM EDT SUN SEP 30 2007 .DISCUSSION... MANY FORECAST CONCERNS WITH THIS FORECAST UPDATE IS THE CHANCE OF PRECIPITATION THIS AFTERNOON. WATER VAPOR IMAGERY AND RUC/NAM SHOWING A DEEP LOW OVER WESTERN KANSAS MOVING NORTHEAST INTO THE RIDGE OVER WESTERN QUEBEC. A LONGWAVE TROUGH IS JUST OFF THE PACIFIC NORTHWEST. OTHER WEAK SHORTWAVES ARE OVER NORTHERN MINNESOTA AND OVER MANITOBA. A PAIR OF LARGE HIGH BLANKETS MUCH OF THE SOUTHERN MISSISSIPPI RIVER VALLEY AND OVER NEW ENGLAND. A FRONTAL SYSTEM EXTENDS FROM A LOW OVER NORTHWEST ONTARIO SOUTHWEST THROUGH NORTHWEST MINNESOTA TO A LOW OVER NORTHEAST NEBRASKA. AN UPPER LEVEL 100+ KNOT JET MAX IS OVER CENTRAL ONTARIO...FOLLOWED BY ANOTHER OVER CENTRAL KANSAS. THIS IS DRAWING DEEP MOISTURE FROM THE GULF INTO THE NORTHERN MISSISSIPPI RIVER VALLEY AND WESTERN END OF THE FORECAST AREA. SHOWERS AND THUNDERSTORMS ARE OCCURRING OVER WESTERN PART OF THE CWA AND OVER CENTRAL ONTARIO IN THE AREA OF HIGHEST MOISTURE AND UPPER LEVEL DIVERGENCE. THE KANSAS LOW WILL MOVE INTO EASTERN NEBRASKA BY LATE AFTERNOON. THE RIDGE OVER WESTERN QUEBEC WILL CONTINUE. A WEAK SHORTWAVE WILL PUSH ACROSS THE WESTERN U.P. DEEP MOISTURE CONTINUES TO REMAIN OVER ONTARIO...MINNESOTA...NORTHWEST WISCONSIN...AND WEST END OF CWA. KMQT 88D AND SURFACE REPORTS INDICATE THAT MOST OF THE RAIN IS COMING FROM HIGH BASED CLOUDS. THUS PLAN TO KEEP RAIN IN THE FORECAST FOR THE AFTERNOON OVER THE WEST AND MOSTLY CLOUDY OVER THE CENTRAL PART WITH MAINLY AC. WINDS WILL REMAIN OUT OF THE SOUTH. SOME OF THE LOW LEVEL JET WILL MIX TO THE SURFACE AS GUSTY CONDITIONS AS INDICATED BY SEVERAL STATIONS ALONG THE LAKE SHORE. PLAN TO UPDATE THE FORECAST TO TWEAK THE WORDING. EXTENDED... TONIGHT...UPPER RIDGING WILL REBUILD ACROSS THE PLAINS AS THE EAST PACIFIC NW TROUGH MOVES INTO WASHINGTON AND OREGON STATE. THIS REBUILDING OF THE UPPER RIDGE WILL FORCE THE UPPER LOW NEAR OMAHA TO LIFT NE AS IT RUNS INTO THE RIDGE TO ITS EAST. BY 12Z MON...THE LOW SHOULD BE LOCATED NEAR APPLETON WI. MORE IMPRESSIVE HEIGHT FALLS COMPARED TO TODAY...ALONG WITH SOME MID-LEVEL FRONTOGENESIS OVER THE WESTERN U.P...SHOULD SUPPORT AN EXPANSION AND INTENSIFICATION OF PCPN OVER THE CWA. WILL RAISE POPS TO CATEGORICAL OVER THE WEST HALF OF THE CWA GIVEN CONSISTENT MODEL AGREEMENT FOR PCPN THERE. FOR THE EASTERN CWA...HAVE ONLY WENT WITH LIKELY VALUES AS HEIGHT FALLS ARE LATEST TO HIT THERE. HIGH PRECIPITABLE WATER VALUES...AROUND 1.5 INCHES OR 250 PERCENT OF NORMAL...COULD SUPPORT SOME HEAVY RAINFALL AMOUNTS. THE NAM INDICATES THIS WITH 3.1 INCHES AT IWD BETWEEN 00-12Z. GIVEN PLENTY OF CLOUD COVER AND HIGH DEWPOINTS SUGGESTS A WARM NIGHT...PROBABLY NOT TOO FAR FROM AVERAGE HIGH TEMPERATURES. MON...RIDGE AXIS OVER THE PLAINS WILL SHIFT INTO WESTERN WI BY 00Z AS THE WESTERN TROUGH CONTINUES TO PLOW EASTWARD. THIS WILL CAUSE THE UPPER LOW TO SHIFT TO NEAR LAKE HURON. DNVA ASSOCIATED WITH THE RIDGE AXIS SHOULD ALLOW SHOWERS TO END BY 18Z OVER THE WEST HALF OF THE CWA AND OVER MUCH OF THE EAST HALF OF THE CWA BY 00Z. WILL MAINTAIN THE IDEA OF LIKELY POPS OVER THE EASTERN CWA IN THE MORNING WITH CHANCE POPS ELSEWHERE. ALTHOUGH THE SHOWERS END...DRYING ALOFT ASSOCIATED WITH THE UPPER RIDGE APPEARS TO SET UP A SUBSIDENCE INVERSION. GIVEN THE TIME OF YEAR AND PLENTY OF MOISTURE FROM THE RAIN TONIGHT SUGGESTS THE POSSIBILITY OF A LOW STRATUS DECK GETTING STUCK OVER MUCH OF THE U.P.. WINDS TURNING NORTH ON THE BACK SIDE OF A SURFACE LOW ASSOCIATED WITH THE UPPER LOW COULD ALSO RESULT IN SOME MIST AND OR DRIZZLE OVER UPSLOPE AREAS. GIVEN ALL THE CLOUD COVER... TEMPERATURES WILL NOT RISE MUCH. MON NIGHT...UPPER RIDGE AXIS MOVES ACROSS THE CWA DURING THE NIGHT WHILE THE WESTERN TROUGH MOVES OUT INTO THE WESTERN PLAINS. SUBSIDENCE UNDER THE RIDGE SHOULD EFFECTIVELY END ANY PCPN IN THE EVENING...WHICH WOULD BE LOCATED IN THE FAR EASTERN PORTION OF THE CWA. STILL...CLOUDS ARE EXPECTED TO LINGER WITH MOISTURE TRAPPED UNDER THE SUBSIDENCE INVERSION. DRYING ABOVE THE INVERSION AND LIGHT WINDS SHOULD SUPPORT FOG DEVELOPMENT OVER LAND...AND PERHAPS ON THE GREAT LAKES TOO. HAVE INCREASED THE COVERAGE TO AREAS OF FOG. IF ANY CLEARING CAN DEVELOP IN THE LOW STRATUS DECK...DENSE FOG DEVELOPING IS NOT OUT OF THE QUESTION. GIVEN CLOUD COVER AND MOISTURE...HAVE STAYED ABOVE THE COLDER MET GUIDANCE WITH READINGS CLOSER TO MAV GUIDANCE. TUE INTO TUE NIGHT...THE BREAK IN PCPN OBSERVED MON NIGHT WILL BE BRIEF AS THE UPPER TROUGH OVER THE WESTERN PLAINS MOVES EAST AT A GOOD CLIP. STRONG DPVA FROM HEIGHT FALLS MOVING ACROSS WARM ADVECTION AT THE LOW LEVELS (ANOTHER 50-60 KT JET AT 850MB PROGGED) SUGGESTS A LINE OF SHOWERS AND THUNDERSTORMS SHOULD FORM IN THE VICINITY OF THE TROUGHS ASSOCIATED SURFACE COLD FRONT. IN ADDITION...STRONG 850MB THETA-E ADVECTION AHEAD OF THE TROUGH MOVING ACROSS WESTERN UPPER MICHIGAN IN THE MORNING COULD SUPPORT SOME SHOWERS AND THUNDERSTORMS (SIMILAR TO TODAY). MODEL RUN-TO-RUN AND BETWEEN MODEL CONSISTENCY IS REMARKABLY GREAT WITH THIS SYSTEM...AND THUS HAVE INCREASED POPS TO LIKELY WITH THE COLD FRONTAL THUNDERSTORMS. VERY STRONG WIND FIELDS ASSOCIATED WITH THE SYSTEM WOULD SUGGEST A SEVERE THREAT...HOWEVER IT APPEARS THERE IS VERY LITTLE CAPE AVAILABLE. SPC DAY 3 OUTLOOK HAS AREA ONLY IN 5 PERCENT AT THIS TIME...AND GIVEN THE LACK OF A SIGNIFICANT AMOUNT OF CAPE...HAVE DECLINED TO MENTION ANY SEVERE POSSIBILITY IN THE HWO. IF MORE SUN CAN OCCUR ON TUE...THEN THE POTENTIAL FOR SEVERE WEATHER WOULD GO UP. MAIN CONCERN WOULD BE HEAVY RAIN GIVEN THAT ANOTHER SURGE OF 1.5-1.75 INCH PRECIPITABLE WATER VALUES ARE PROGGED WITH THE FRONT. CLEARING IS EXPECTED TO FOLLOW BEHIND THE COLD FRONT AND UPPER TROUGH AS PRECIPITABLE WATER VALUES FALL TO 0.5 INCHES ACROSS THE ENTIRE CWA BY 12Z WED. THIS COOLER AND DRY AIR BUT BREEZY WEST TO NORTHWEST WINDS SHOULD RESULT IN READINGS SIMILAR TO THOSE MON NIGHT. WED THROUGH SUN...FLOW TURNS ZONAL WED...WITH WESTERLY FLOW HELPING TO BRING MILD PACIFIC AIR INTO THE AREA. THEN FOR THU THROUGH SAT...ANOTHER SIGNIFICANT TROUGH IS EXPECTED TO DROP SOUTH THROUGH THE WESTERN STATES...HEADING OUT INTO THE PLAINS ON SAT. THE RESULT IS THE DEVELOPMENT OF A LOW PRESSURE SYSTEM OVER THE DAKOTAS. WARM AIR ADVECTION AHEAD OF THE SYSTEM SHOULD HELP KEEP TEMPERATURES WELL ABOVE NORMAL. GFS/ECMWF BOTH DEPICT 850MB TEMPS CLIMBING TO 14-16C. BY SAT...WE COULD BE TALKING ABOUT ANOTHER DAY OF HUMID CONDITIONS AS PRECIPITABLE WATER VALUES INCREASE TO 1.5 TO 1.75 INCHES AHEAD OF THE APPROACHING TROUGH/COLD FRONT. UPPER TROUGH CROSSING THE AREA SAT NIGHT WILL BRING IN MUCH COOLER CONDITIONS ON SUN...ASSUMING THE TROUGH CAN PUSH EAST INTO THE RIDGE THAT HAS BEEN BUILT OUT AHEAD OF IT. WILL NEED TO WATCH THIS SCENARIO CLOSELY AS THE PATTERN COULD BECOME FAVORABLE FOR VERY HEAVY RAIN. NOTE: WE NEED 0.28 INCHES OF PCPN AT THE OFFICE BY 05Z TONIGHT TO BREAK THE ALL TIME WETTEST SEPTEMBER RECORD. PREVIOUS RECORD IS 7.60 SET IN 1968. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... LATEST KMQT VAD WIND PROFILE INDICATES 40KT SRLY WINDS AT 500FT AGL. SO...LLWS WILL CONTINUE TO BE MENTIONED AT KCMX/KSAW UNTIL MIXED LAYER BUILDS SUFFICIENTLY TO EASE SHARP SPEED CHANGE BTWN SFC WINDS AND STRONGER WINDS JUST OFF THE DECK. IN FACT...SRLY WINDS SHOULD BECOME FAIRLY STRONG AND GUSTY...ESPECIALLY AT KSAW BY THE AFTN HRS AS MIXED LAYER BUILDS. LOW-LEVEL JET IS CURRENTLY HELPING TO GENERATE A LARGE AREA OF SHRA/TSRA ACROSS MN/FAR NW WI/WRN UPPER MI. PCPN WILL AFFECT KCMX THRU ABOUT 14Z. BULK OF PCPN WILL PASS W OF KSAW...BUT IT IS CLOSE ENOUGH TO WARRANT A MENTION OF -SHRA THRU ABOUT 14Z. IN ANYCASE...VFR CONDITIONS WILL PREVAIL INTO MOST OF THE AFTN. ADDITIONAL SHRA AND ISOLD TSRA SHOULD MOVE INTO WRN UPPER MI...INCLUDING KCMX...MID TO LATE AFTN AS LOW PRES/SFC TROF APPROACHES. DEFORMATION ZONE PCPN...MODERATE TO HEAVY AT TIMES... WILL SLOWLY EDGE E THRU W INTO CNTRL UPPER MI THIS EVENING WITH MVFR CIGS/VSBYS. IFR CONDITIONS COULD OCCUR DURING PERIODS OF HEAVIER PCPN. CONDITIONS SHOULD TREND TO PREVAILING IFR OVERNIGHT AS SFC TROF HEADS E ACROSS WRN UPPER MI. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FCST ISSUANCE)... S WINDS...GENERALLY IN THE 15 TO 25 KT RANGE...WILL CONTINUE TODAY AHEAD OF A LOW PRES TROUGH OVER THE PLAINS. EXPECT FREQUENT GUSTS TO 30KT OVER THE E HALF OF THE LAKE WHICH IS FAVORED FOR STRONGER WINDS IN SRLY FLOW REGIMES. MAY SEE A FEW 35KT GALE FORCE GUSTS AS WELL. THE AREA AROUND GRAND MARAIS AT THE E END OF PICTURED ROCKS NATIONAL LAKESHORE IS ONE LOCATION THAT MAY SEE THE HIGHEST WINDS. WINDS WILL DIMINISH TONIGHT AND ESPECIALLY MON AS WEAKENING LOW PRES MOVES TO THE UPPER GREAT LAKES REGION. WILL NEED TO WATCH FOR FOG DEVELOPMENT AS THE WINDS DIMINISH. NEXT ACTIVE LOW PRES TROUGH WILL RACE E AND CROSS LAKE SUPERIOR TUE NIGHT. SRLY WINDS WILL AGAIN RAMP UP IN ADVANCE OF THIS TROUGH...AND IT`S NOT OUT OF THE QUESTION THAT A FEW GALE FORCE GUSTS COULD OCCUR OVER THE E HALF OF THE LAKE LATE TUE AFTN/EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ SYNOPSIS/FIRST PERIOD...DLG EXTENDED DISCUSSION...AJ AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 745 AM EDT SUN SEP 30 2007 UPDATED FOR AVIATION DISCUSSION .SYNOPSIS (ISSUED AT 422 AM EDT)... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING COVERING MUCH OF THE EAST HALF OF THE U.S. INTO SE CANADA...WITH 500MB HEIGHTS OF 582 DAM OVER UPPER MICHIGAN. TO THE WEST OF THE RIDGE...THE FLOW SPLITS WITH A SHRTWV TROUGH OVER SASKATCHEWAN AND AN UPPER LOW OVER NW COLORADO. FARTHER WEST...A DEEP TROUGH CAN BE SEEN DIGGING SE THROUGH THE EAST PACIFIC. CLOSER TO HOME...AN AREA OF SHOWERS AND A FEW EMBEDDED THUNDERSTORMS CROSSED UPPER MI LAST EVENING AND NOW ARE SITUATED OVER NE LAKE SUPERIOR. ANOTHER CLUSTER OF SHOWERS AND EMBEDDED TSRA ARE EXPANDING IN THE MPX AREA AND IN THE VICINITY OF GRB. BOTH OF THESE ARES ARE LOCATED IN A FAIRLY STRONG 850MB THETA-E ADVECTION ZONE ON TOP OF THE UPPER LEVEL RIDGE. 00Z MPX SOUNDING DEPICTED SSW WINDS OF 60 KT AT 850MB WITH A 15C TEMP AND 9C DEWPOINT. THESE STRONG WINDS AND 850MB MOISTURE TRANSPORT EXTEND TO THE SW INTO WESTERN KANSAS AND CENTRAL NEBRASKA WITH PROFILERS ALSO DEPICTING 55-60 KT WINDS AT 850MB. WITH THIS STRONG WARM ADVECTION AND HEIGHT FALLS DOWNSTREAM OF THE NW COLORADO UPPER LOW...STORMS HAVE OCCURRED ALONG THE WEST SIDE OF THE LOW LEVEL JET. IN ADDITION...THE WARM ADVECTION AND HEIGHT FALLS ARE SUPPORTING A 999MB LOW PRESSURE TROUGH FROM MANITOBA INTO NE COLORADO. DEWPOINTS ARE BECOMING SOMEWHAT HUMID...ESPECIALLY FOR LATE SEPTEMBER...WITH READINGS IN THE UPPER 50S TO LOW 60S THROUGH MUCH OF THE EASTERN PLAINS. HIGHER DEWPOINTS THAN THIS EXIST MUCH FURTHER SOUTH...OVER WEST TEXAS. && .DISCUSSION (ISSUED AT 422 AM EDT)... MANY FORECAST CONCERNS...MOSTLY PCPN FOR TODAY THROUGH MON AND TUE INTO TUE NIGHT. TODAY...UPPER LOW IN NW COLORADO WILL CONTINUE TO GET PUSHED EASTWARD IN RESPONSE TO THE EAST PACIFIC TROUGH REACHING THE PACIFIC NW COAST. BY 00Z...MODELS SHOW THE UPPER LOW NEAR OMAHA. ALTHOUGH THE LOW IS PUSHING EASTWARD...MID/UPPER LEVEL HEIGHTS REALLY DO NOT FALL A WHOLE LOT OVER THE CWA UNTIL LATE...LIKELY DUE TO PERSISTENT WARM ADVECTION AHEAD OF THE LOW. THUS...AFTER THE CURRENT WARM ADVECTION PCPN THIS MORNING...THINGS SHOULD DIMINISH AT LEAST FOR THE EASTERN CWA. WILL MAINTAIN POPS FOR WESTERN LAKE SUPERIOR AND THE WEST HALF OF THE U.P....AND ESPECIALLY AFTER 18Z AS HEIGHTS BEGIN TO FALL OUT THERE. CLOUD COVER THIS MORNING OVER THE EAST HALF OF THE CWA SHOULD CLEAR OUT THIS AFTERNOON...SETTING THE STAGE FOR A BREEZY DAY. BASED ON MOMENTUM TRANSFER...GUSTS SHOULD END UP IN THE 30-35 KT RANGE...JUST BELOW ADVISORY CRITERIA. HOWEVER...WOULD NOT BE SURPRISED TO SEE LOCATIONS SUCH AS MUNISING AND GRAND MARAIS GET CLOSE OR SLIGHTLY OVER ADVISORY CRITERIA GIVEN THEIR FAVORED FLOW FOR SOUTH WINDS AND SOUNDINGS SUGGESTING 40-45 KT WINDS AT 925MB. THE WINDS AND CLEARING...ALONG WITH 850MB TEMPS AROUND 15C SHOULD ALLOW FOR TEMPS TO CLIMB INTO THE LOW TO MID 70S. IF MORE SUN OCCURS THEN EXPECTED...THERE IS A CHANCE TO COME CLOSE TO OR TIE OUR RECORD HIGH AT THE OFFICE OF 80 SET IN 2000. TONIGHT...UPPER RIDGING WILL REBUILD ACROSS THE PLAINS AS THE EAST PACIFIC NW TROUGH MOVES INTO WASHINGTON AND OREGON STATE. THIS REBUILDING OF THE UPPER RIDGE WILL FORCE THE UPPER LOW NEAR OMAHA TO LIFT NE AS IT RUNS INTO THE RIDGE TO ITS EAST. BY 12Z MON...THE LOW SHOULD BE LOCATED NEAR APPLETON WI. MORE IMPRESSIVE HEIGHT FALLS COMPARED TO TODAY...ALONG WITH SOME MID-LEVEL FRONTOGENESIS OVER THE WESTERN U.P...SHOULD SUPPORT AN EXPANSION AND INTENSIFICATION OF PCPN OVER THE CWA. WILL RAISE POPS TO CATEGORICAL OVER THE WEST HALF OF THE CWA GIVEN CONSISTENT MODEL AGREEMENT FOR PCPN THERE. FOR THE EASTERN CWA...HAVE ONLY WENT WITH LIKELY VALUES AS HEIGHT FALLS ARE LATEST TO HIT THERE. HIGH PRECIPITABLE WATER VALUES...AROUND 1.5 INCHES OR 250 PERCENT OF NORMAL...COULD SUPPORT SOME HEAVY RAINFALL AMOUNTS. THE NAM INDICATES THIS WITH 3.1 INCHES AT IWD BETWEEN 00-12Z. GIVEN PLENTY OF CLOUD COVER AND HIGH DEWPOINTS SUGGESTS A WARM NIGHT...PROBABLY NOT TOO FAR FROM AVERAGE HIGH TEMPERATURES. MON...RIDGE AXIS OVER THE PLAINS WILL SHIFT INTO WESTERN WI BY 00Z AS THE WESTERN TROUGH CONTINUES TO PLOW EASTWARD. THIS WILL CAUSE THE UPPER LOW TO SHIFT TO NEAR LAKE HURON. DNVA ASSOCIATED WITH THE RIDGE AXIS SHOULD ALLOW SHOWERS TO END BY 18Z OVER THE WEST HALF OF THE CWA AND OVER MUCH OF THE EAST HALF OF THE CWA BY 00Z. WILL MAINTAIN THE IDEA OF LIKELY POPS OVER THE EASTERN CWA IN THE MORNING WITH CHANCE POPS ELSEWHERE. ALTHOUGH THE SHOWERS END...DRYING ALOFT ASSOCIATED WITH THE UPPER RIDGE APPEARS TO SET UP A SUBSIDENCE INVERSION. GIVEN THE TIME OF YEAR AND PLENTY OF MOISTURE FROM THE RAIN TONIGHT SUGGESTS THE POSSIBILITY OF A LOW STRATUS DECK GETTING STUCK OVER MUCH OF THE U.P.. WINDS TURNING NORTH ON THE BACK SIDE OF A SURFACE LOW ASSOCIATED WITH THE UPPER LOW COULD ALSO RESULT IN SOME MIST AND OR DRIZZLE OVER UPSLOPE AREAS. GIVEN ALL THE CLOUD COVER... TEMPERATURES WILL NOT RISE MUCH. MON NIGHT...UPPER RIDGE AXIS MOVES ACROSS THE CWA DURING THE NIGHT WHILE THE WESTERN TROUGH MOVES OUT INTO THE WESTERN PLAINS. SUBSIDENCE UNDER THE RIDGE SHOULD EFFECTIVELY END ANY PCPN IN THE EVENING...WHICH WOULD BE LOCATED IN THE FAR EASTERN PORTION OF THE CWA. STILL...CLOUDS ARE EXPECTED TO LINGER WITH MOISTURE TRAPPED UNDER THE SUBSIDENCE INVERSION. DRYING ABOVE THE INVERSION AND LIGHT WINDS SHOULD SUPPORT FOG DEVELOPMENT OVER LAND...AND PERHAPS ON THE GREAT LAKES TOO. HAVE INCREASED THE COVERAGE TO AREAS OF FOG. IF ANY CLEARING CAN DEVELOP IN THE LOW STRATUS DECK...DENSE FOG DEVELOPING IS NOT OUT OF THE QUESTION. GIVEN CLOUD COVER AND MOISTURE...HAVE STAYED ABOVE THE COLDER MET GUIDANCE WITH READINGS CLOSER TO MAV GUIDANCE. TUE INTO TUE NIGHT...THE BREAK IN PCPN OBSERVED MON NIGHT WILL BE BRIEF AS THE UPPER TROUGH OVER THE WESTERN PLAINS MOVES EAST AT A GOOD CLIP. STRONG DPVA FROM HEIGHT FALLS MOVING ACROSS WARM ADVECTION AT THE LOW LEVELS (ANOTHER 50-60 KT JET AT 850MB PROGGED) SUGGESTS A LINE OF SHOWERS AND THUNDERSTORMS SHOULD FORM IN THE VICINITY OF THE TROUGHS ASSOCIATED SURFACE COLD FRONT. IN ADDITION...STRONG 850MB THETA-E ADVECTION AHEAD OF THE TROUGH MOVING ACROSS WESTERN UPPER MICHIGAN IN THE MORNING COULD SUPPORT SOME SHOWERS AND THUNDERSTORMS (SIMILAR TO TODAY). MODEL RUN-TO-RUN AND BETWEEN MODEL CONSISTENCY IS REMARKABLY GREAT WITH THIS SYSTEM...AND THUS HAVE INCREASED POPS TO LIKELY WITH THE COLD FRONTAL THUNDERSTORMS. VERY STRONG WIND FIELDS ASSOCIATED WITH THE SYSTEM WOULD SUGGEST A SEVERE THREAT...HOWEVER IT APPEARS THERE IS VERY LITTLE CAPE AVAILABLE. SPC DAY 3 OUTLOOK HAS AREA ONLY IN 5 PERCENT AT THIS TIME...AND GIVEN THE LACK OF A SIGNIFICANT AMOUNT OF CAPE...HAVE DECLINED TO MENTION ANY SEVERE POSSIBILITY IN THE HWO. IF MORE SUN CAN OCCUR ON TUE...THEN THE POTENTIAL FOR SEVERE WEATHER WOULD GO UP. MAIN CONCERN WOULD BE HEAVY RAIN GIVEN THAT ANOTHER SURGE OF 1.5-1.75 INCH PRECIPITABLE WATER VALUES ARE PROGGED WITH THE FRONT. CLEARING IS EXPECTED TO FOLLOW BEHIND THE COLD FRONT AND UPPER TROUGH AS PRECIPITABLE WATER VALUES FALL TO 0.5 INCHES ACROSS THE ENTIRE CWA BY 12Z WED. THIS COOLER AND DRY AIR BUT BREEZY WEST TO NORTHWEST WINDS SHOULD RESULT IN READINGS SIMILAR TO THOSE MON NIGHT. WED THROUGH SUN...FLOW TURNS ZONAL WED...WITH WESTERLY FLOW HELPING TO BRING MILD PACIFIC AIR INTO THE AREA. THEN FOR THU THROUGH SAT...ANOTHER SIGNIFICANT TROUGH IS EXPECTED TO DROP SOUTH THROUGH THE WESTERN STATES...HEADING OUT INTO THE PLAINS ON SAT. THE RESULT IS THE DEVELOPMENT OF A LOW PRESSURE SYSTEM OVER THE DAKOTAS. WARM AIR ADVECTION AHEAD OF THE SYSTEM SHOULD HELP KEEP TEMPERATURES WELL ABOVE NORMAL. GFS/ECMWF BOTH DEPICT 850MB TEMPS CLIMBING TO 14-16C. BY SAT...WE COULD BE TALKING ABOUT ANOTHER DAY OF HUMID CONDITIONS AS PRECIPITABLE WATER VALUES INCREASE TO 1.5 TO 1.75 INCHES AHEAD OF THE APPROACHING TROUGH/COLD FRONT. UPPER TROUGH CROSSING THE AREA SAT NIGHT WILL BRING IN MUCH COOLER CONDITIONS ON SUN...ASSUMING THE TROUGH CAN PUSH EAST INTO THE RIDGE THAT HAS BEEN BUILT OUT AHEAD OF IT. WILL NEED TO WATCH THIS SCENARIO CLOSELY AS THE PATTERN COULD BECOME FAVORABLE FOR VERY HEAVY RAIN. NOTE: WE NEED 0.28 INCHES OF PCPN AT THE OFFICE BY 05Z TONIGHT TO BREAK THE ALL TIME WETTEST SEPTEMBER RECORD. PREVIOUS RECORD IS 7.60 SET IN 1968. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... LATEST KMQT VAD WIND PROFILE INDICATES 40KT SRLY WINDS AT 500FT AGL. SO...LLWS WILL CONTINUE TO BE MENTIONED AT KCMX/KSAW UNTIL MIXED LAYER BUILDS SUFFICIENTLY TO EASE SHARP SPEED CHANGE BTWN SFC WINDS AND STRONGER WINDS JUST OFF THE DECK. IN FACT...SRLY WINDS SHOULD BECOME FAIRLY STRONG AND GUSTY...ESPECIALLY AT KSAW BY THE AFTN HRS AS MIXED LAYER BUILDS. LOW-LEVEL JET IS CURRENTLY HELPING TO GENERATE A LARGE AREA OF SHRA/TSRA ACROSS MN/FAR NW WI/WRN UPPER MI. PCPN WILL AFFECT KCMX THRU ABOUT 14Z. BULK OF PCPN WILL PASS W OF KSAW...BUT IT IS CLOSE ENOUGH TO WARRANT A MENTION OF -SHRA THRU ABOUT 14Z. IN ANYCASE...VFR CONDITIONS WILL PREVAIL INTO MOST OF THE AFTN. ADDITIONAL SHRA AND ISOLD TSRA SHOULD MOVE INTO WRN UPPER MI...INCLUDING KCMX...MID TO LATE AFTN AS LOW PRES/SFC TROF APPROACHES. DEFORMATION ZONE PCPN...MODERATE TO HEAVY AT TIMES... WILL SLOWLY EDGE E THRU W INTO CNTRL UPPER MI THIS EVENING WITH MVFR CIGS/VSBYS. IFR CONDITIONS COULD OCCUR DURING PERIODS OF HEAVIER PCPN. CONDITIONS SHOULD TREND TO PREVAILING IFR OVERNIGHT AS SFC TROF HEADS E ACROSS WRN UPPER MI. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FCST ISSUANCE)... S WINDS...GENERALLY IN THE 15 TO 25 KT RANGE...WILL CONTINUE TODAY AHEAD OF A LOW PRES TROUGH OVER THE PLAINS. EXPECT FREQUENT GUSTS TO 30KT OVER THE E HALF OF THE LAKE WHICH IS FAVORED FOR STRONGER WINDS IN SRLY FLOW REGIMES. MAY SEE A FEW 35KT GALE FORCE GUSTS AS WELL. THE AREA AROUND GRAND MARAIS AT THE E END OF PICTURED ROCKS NATIONAL LAKESHORE IS ONE LOCATION THAT MAY SEE THE HIGHEST WINDS. WINDS WILL DIMINISH TONIGHT AND ESPECIALLY MON AS WEAKENING LOW PRES MOVES TO THE UPPER GREAT LAKES REGION. WILL NEED TO WATCH FOR FOG DEVELOPMENT AS THE WINDS DIMINISH. NEXT ACTIVE LOW PRES TROUGH WILL RACE E AND CROSS LAKE SUPERIOR TUE NIGHT. SRLY WINDS WILL AGAIN RAMP UP IN ADVANCE OF THIS TROUGH...AND IT`S NOT OUT OF THE QUESTION THAT A FEW GALE FORCE GUSTS COULD OCCUR OVER THE E HALF OF THE LAKE LATE TUE AFTN/EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 422 AM EDT SUN SEP 30 2007 .SYNOPSIS... 07Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING COVERING MUCH OF THE EAST HALF OF THE U.S. INTO SE CANADA...WITH 500MB HEIGHTS OF 582 DAM OVER UPPER MICHIGAN. TO THE WEST OF THE RIDGE...THE FLOW SPLITS WITH A SHRTWV TROUGH OVER SASKATCHEWAN AND AN UPPER LOW OVER NW COLORADO. FARTHER WEST...A DEEP TROUGH CAN BE SEEN DIGGING SE THROUGH THE EAST PACIFIC. CLOSER TO HOME...AN AREA OF SHOWERS AND A FEW EMBEDDED THUNDERSTORMS CROSSED UPPER MI LAST EVENING AND NOW ARE SITUATED OVER NE LAKE SUPERIOR. ANOTHER CLUSTER OF SHOWERS AND EMBEDDED TSRA ARE EXPANDING IN THE MPX AREA AND IN THE VICINITY OF GRB. BOTH OF THESE ARES ARE LOCATED IN A FAIRLY STRONG 850MB THETA-E ADVECTION ZONE ON TOP OF THE UPPER LEVEL RIDGE. 00Z MPX SOUNDING DEPICTED SSW WINDS OF 60 KT AT 850MB WITH A 15C TEMP AND 9C DEWPOINT. THESE STRONG WINDS AND 850MB MOISTURE TRANSPORT EXTEND TO THE SW INTO WESTERN KANSAS AND CENTRAL NEBRASKA WITH PROFILERS ALSO DEPICTING 55-60 KT WINDS AT 850MB. WITH THIS STRONG WARM ADVECTION AND HEIGHT FALLS DOWNSTREAM OF THE NW COLORADO UPPER LOW...STORMS HAVE OCCURRED ALONG THE WEST SIDE OF THE LOW LEVEL JET. IN ADDITION...THE WARM ADVECTION AND HEIGHT FALLS ARE SUPPORTING A 999MB LOW PRESSURE TROUGH FROM MANITOBA INTO NE COLORADO. DEWPOINTS ARE BECOMING SOMEWHAT HUMID...ESPECIALLY FOR LATE SEPTEMBER...WITH READINGS IN THE UPPER 50S TO LOW 60S THROUGH MUCH OF THE EASTERN PLAINS. HIGHER DEWPOINTS THAN THIS EXIST MUCH FURTHER SOUTH...OVER WEST TEXAS. && .DISCUSSION... MANY FORECAST CONCERNS...MOSTLY PCPN FOR TODAY THROUGH MON AND TUE INTO TUE NIGHT. TODAY...UPPER LOW IN NW COLORADO WILL CONTINUE TO GET PUSHED EASTWARD IN RESPONSE TO THE EAST PACIFIC TROUGH REACHING THE PACIFIC NW COAST. BY 00Z...MODELS SHOW THE UPPER LOW NEAR OMAHA. ALTHOUGH THE LOW IS PUSHING EASTWARD...MID/UPPER LEVEL HEIGHTS REALLY DO NOT FALL A WHOLE LOT OVER THE CWA UNTIL LATE...LIKELY DUE TO PERSISTENT WARM ADVECTION AHEAD OF THE LOW. THUS...AFTER THE CURRENT WARM ADVECTION PCPN THIS MORNING...THINGS SHOULD DIMINISH AT LEAST FOR THE EASTERN CWA. WILL MAINTAIN POPS FOR WESTERN LAKE SUPERIOR AND THE WEST HALF OF THE U.P....AND ESPECIALLY AFTER 18Z AS HEIGHTS BEGIN TO FALL OUT THERE. CLOUD COVER THIS MORNING OVER THE EAST HALF OF THE CWA SHOULD CLEAR OUT THIS AFTERNOON...SETTING THE STAGE FOR A BREEZY DAY. BASED ON MOMENTUM TRANSFER...GUSTS SHOULD END UP IN THE 30-35 KT RANGE...JUST BELOW ADVISORY CRITERIA. HOWEVER...WOULD NOT BE SURPRISED TO SEE LOCATIONS SUCH AS MUNISING AND GRAND MARAIS GET CLOSE OR SLIGHTLY OVER ADVISORY CRITERIA GIVEN THEIR FAVORED FLOW FOR SOUTH WINDS AND SOUNDINGS SUGGESTING 40-45 KT WINDS AT 925MB. THE WINDS AND CLEARING...ALONG WITH 850MB TEMPS AROUND 15C SHOULD ALLOW FOR TEMPS TO CLIMB INTO THE LOW TO MID 70S. IF MORE SUN OCCURS THEN EXPECTED...THERE IS A CHANCE TO COME CLOSE TO OR TIE OUR RECORD HIGH AT THE OFFICE OF 80 SET IN 2000. TONIGHT...UPPER RIDGING WILL REBUILD ACROSS THE PLAINS AS THE EAST PACIFIC NW TROUGH MOVES INTO WASHINGTON AND OREGON STATE. THIS REBUILDING OF THE UPPER RIDGE WILL FORCE THE UPPER LOW NEAR OMAHA TO LIFT NE AS IT RUNS INTO THE RIDGE TO ITS EAST. BY 12Z MON...THE LOW SHOULD BE LOCATED NEAR APPLETON WI. MORE IMPRESSIVE HEIGHT FALLS COMPARED TO TODAY...ALONG WITH SOME MID-LEVEL FRONTOGENESIS OVER THE WESTERN U.P...SHOULD SUPPORT AN EXPANSION AND INTENSIFICATION OF PCPN OVER THE CWA. WILL RAISE POPS TO CATEGORICAL OVER THE WEST HALF OF THE CWA GIVEN CONSISTENT MODEL AGREEMENT FOR PCPN THERE. FOR THE EASTERN CWA...HAVE ONLY WENT WITH LIKELY VALUES AS HEIGHT FALLS ARE LATEST TO HIT THERE. HIGH PRECIPITABLE WATER VALUES...AROUND 1.5 INCHES OR 250 PERCENT OF NORMAL...COULD SUPPORT SOME HEAVY RAINFALL AMOUNTS. THE NAM INDICATES THIS WITH 3.1 INCHES AT IWD BETWEEN 00-12Z. GIVEN PLENTY OF CLOUD COVER AND HIGH DEWPOINTS SUGGESTS A WARM NIGHT...PROBABLY NOT TOO FAR FROM AVERAGE HIGH TEMPERATURES. MON...RIDGE AXIS OVER THE PLAINS WILL SHIFT INTO WESTERN WI BY 00Z AS THE WESTERN TROUGH CONTINUES TO PLOW EASTWARD. THIS WILL CAUSE THE UPPER LOW TO SHIFT TO NEAR LAKE HURON. DNVA ASSOCIATED WITH THE RIDGE AXIS SHOULD ALLOW SHOWERS TO END BY 18Z OVER THE WEST HALF OF THE CWA AND OVER MUCH OF THE EAST HALF OF THE CWA BY 00Z. WILL MAINTAIN THE IDEA OF LIKELY POPS OVER THE EASTERN CWA IN THE MORNING WITH CHANCE POPS ELSEWHERE. ALTHOUGH THE SHOWERS END...DRYING ALOFT ASSOCIATED WITH THE UPPER RIDGE APPEARS TO SET UP A SUBSIDENCE INVERSION. GIVEN THE TIME OF YEAR AND PLENTY OF MOISTURE FROM THE RAIN TONIGHT SUGGESTS THE POSSIBILITY OF A LOW STRATUS DECK GETTING STUCK OVER MUCH OF THE U.P.. WINDS TURNING NORTH ON THE BACK SIDE OF A SURFACE LOW ASSOCIATED WITH THE UPPER LOW COULD ALSO RESULT IN SOME MIST AND OR DRIZZLE OVER UPSLOPE AREAS. GIVEN ALL THE CLOUD COVER... TEMPERATURES WILL NOT RISE MUCH. MON NIGHT...UPPER RIDGE AXIS MOVES ACROSS THE CWA DURING THE NIGHT WHILE THE WESTERN TROUGH MOVES OUT INTO THE WESTERN PLAINS. SUBSIDENCE UNDER THE RIDGE SHOULD EFFECTIVELY END ANY PCPN IN THE EVENING...WHICH WOULD BE LOCATED IN THE FAR EASTERN PORTION OF THE CWA. STILL...CLOUDS ARE EXPECTED TO LINGER WITH MOISTURE TRAPPED UNDER THE SUBSIDENCE INVERSION. DRYING ABOVE THE INVERSION AND LIGHT WINDS SHOULD SUPPORT FOG DEVELOPMENT OVER LAND...AND PERHAPS ON THE GREAT LAKES TOO. HAVE INCREASED THE COVERAGE TO AREAS OF FOG. IF ANY CLEARING CAN DEVELOP IN THE LOW STRATUS DECK...DENSE FOG DEVELOPING IS NOT OUT OF THE QUESTION. GIVEN CLOUD COVER AND MOISTURE...HAVE STAYED ABOVE THE COLDER MET GUIDANCE WITH READINGS CLOSER TO MAV GUIDANCE. TUE INTO TUE NIGHT...THE BREAK IN PCPN OBSERVED MON NIGHT WILL BE BRIEF AS THE UPPER TROUGH OVER THE WESTERN PLAINS MOVES EAST AT A GOOD CLIP. STRONG DPVA FROM HEIGHT FALLS MOVING ACROSS WARM ADVECTION AT THE LOW LEVELS (ANOTHER 50-60 KT JET AT 850MB PROGGED) SUGGESTS A LINE OF SHOWERS AND THUNDERSTORMS SHOULD FORM IN THE VICINITY OF THE TROUGHS ASSOCIATED SURFACE COLD FRONT. IN ADDITION...STRONG 850MB THETA-E ADVECTION AHEAD OF THE TROUGH MOVING ACROSS WESTERN UPPER MICHIGAN IN THE MORNING COULD SUPPORT SOME SHOWERS AND THUNDERSTORMS (SIMILAR TO TODAY). MODEL RUN-TO-RUN AND BETWEEN MODEL CONSISTENCY IS REMARKABLY GREAT WITH THIS SYSTEM...AND THUS HAVE INCREASED POPS TO LIKELY WITH THE COLD FRONTAL THUNDERSTORMS. VERY STRONG WIND FIELDS ASSOCIATED WITH THE SYSTEM WOULD SUGGEST A SEVERE THREAT...HOWEVER IT APPEARS THERE IS VERY LITTLE CAPE AVAILABLE. SPC DAY 3 OUTLOOK HAS AREA ONLY IN 5 PERCENT AT THIS TIME...AND GIVEN THE LACK OF A SIGNIFICANT AMOUNT OF CAPE...HAVE DECLINED TO MENTION ANY SEVERE POSSIBILITY IN THE HWO. IF MORE SUN CAN OCCUR ON TUE...THEN THE POTENTIAL FOR SEVERE WEATHER WOULD GO UP. MAIN CONCERN WOULD BE HEAVY RAIN GIVEN THAT ANOTHER SURGE OF 1.5-1.75 INCH PRECIPITABLE WATER VALUES ARE PROGGED WITH THE FRONT. CLEARING IS EXPECTED TO FOLLOW BEHIND THE COLD FRONT AND UPPER TROUGH AS PRECIPITABLE WATER VALUES FALL TO 0.5 INCHES ACROSS THE ENTIRE CWA BY 12Z WED. THIS COOLER AND DRY AIR BUT BREEZY WEST TO NORTHWEST WINDS SHOULD RESULT IN READINGS SIMILAR TO THOSE MON NIGHT. WED THROUGH SUN...FLOW TURNS ZONAL WED...WITH WESTERLY FLOW HELPING TO BRING MILD PACIFIC AIR INTO THE AREA. THEN FOR THU THROUGH SAT...ANOTHER SIGNIFICANT TROUGH IS EXPECTED TO DROP SOUTH THROUGH THE WESTERN STATES...HEADING OUT INTO THE PLAINS ON SAT. THE RESULT IS THE DEVELOPMENT OF A LOW PRESSURE SYSTEM OVER THE DAKOTAS. WARM AIR ADVECTION AHEAD OF THE SYSTEM SHOULD HELP KEEP TEMPERATURES WELL ABOVE NORMAL. GFS/ECMWF BOTH DEPICT 850MB TEMPS CLIMBING TO 14-16C. BY SAT...WE COULD BE TALKING ABOUT ANOTHER DAY OF HUMID CONDITIONS AS PRECIPITABLE WATER VALUES INCREASE TO 1.5 TO 1.75 INCHES AHEAD OF THE APPROACHING TROUGH/COLD FRONT. UPPER TROUGH CROSSING THE AREA SAT NIGHT WILL BRING IN MUCH COOLER CONDITIONS ON SUN...ASSUMING THE TROUGH CAN PUSH EAST INTO THE RIDGE THAT HAS BEEN BUILT OUT AHEAD OF IT. WILL NEED TO WATCH THIS SCENARIO CLOSELY AS THE PATTERN COULD BECOME FAVORABLE FOR VERY HEAVY RAIN. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... A BAND OF SHOWERS AND ISOLATED THUNDERSTORMS SUPPORTED BY 40-50 KT INFLOW INTO A 850-700 MB WARM FRONT WILL CONTINUE TO LIFT NORTHEAST OUT OF UPPER MICHIGAN OVERNIGHT. LLWS CONDITIONS ARE EXPECTED TO PERSIST DURING THE NIGHT WITH THE PRES GRADIENT REMAINING TIGHT AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM. OTHERWISE...EXPECT VFR CONDITIONS AFTER THE SHRA/TSRA DEPART AFT 06Z. SURFACE HEATING WILL AID MIXING WITH SOUTH WIND GUSTS TO AROUND 25 KT EXPECTED. ADDITIONAL SHRA AND ISOLD TSRA MAY MOVE INTO WEST UPPER MI... INCLUDING KCMX...BY MID TO LATE AFTERNOON AS THE LOW APPROACHES. THE DEFORMATION ZONE PCPN...MODERATE TO HEAVY AT TIMES...WILL SLOWLY EDGE EASTWARD THROUGH WEST INTO CENTRAL UPPER MI WEDNESDAY EVENING WITH MVFR CIGS/VSBYS. NOTE: WE NEED 0.28 INCHES OF PCPN AT THE OFFICE BY 05Z TONIGHT TO BREAK THE ALL TIME WETTEST SEPTEMBER RECORD. PREVIOUS RECORD IS 7.60 SET IN 1968. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FCST ISSUANCE)... S WINDS...GENERALLY IN THE 15 TO 25 KT RANGE...WILL CONTINUE TODAY AHEAD OF A LOW PRES TROUGH OVER THE PLAINS. EXPECT FREQUENT GUSTS TO 30KT OVER THE E HALF OF THE LAKE WHICH IS FAVORED FOR STRONGER WINDS IN SRLY FLOW REGIMES. MAY SEE A FEW 35KT GALE FORCE GUSTS AS WELL. THE AREA AROUND GRAND MARAIS AT THE E END OF PICTURED ROCKS NATIONAL LAKESHORE IS ONE LOCATION THAT MAY SEE THE HIGHEST WINDS. WINDS WILL DIMINISH TONIGHT AND ESPECIALLY MON AS WEAKENING LOW PRES MOVES TO THE UPPER GREAT LAKES REGION. WILL NEED TO WATCH FOR FOG DEVELOPMENT AS THE WINDS DIMINISH. NEXT ACTIVE LOW PRES TROUGH WILL RACE E AND CROSS LAKE SUPERIOR TUE NIGHT. SRLY WINDS WILL AGAIN RAMP UP IN ADVANCE OF THIS TROUGH...AND IT`S NOT OUT OF THE QUESTION THAT A FEW GALE FORCE GUSTS COULD OCCUR OVER THE E HALF OF THE LAKE LATE TUE AFTN/EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...JLB MARINE...ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 130 AM EDT SUN SEP 30 2007 UPDATED FOR AVIATION DISCUSSION .UPDATE (ISSUED AT 1020 PM EDT)... SHOWERS AND ISOLATED THUNDESTORMS SUPPORTED BY STRONG BAND OF 305K-310K ISENTROPIC LIFT...50-55 KT SW INFLOW TOWARD THE 800-700 MB FRONT...AND A WEAK SHORTWAVE TROUGH WERE LIFTING STEADILY ENE THROUGH UPPER MI. SOME REDEVELOPMENT ON THE SW EDGE HAS BEEN OVSERVED AND A FEW ADDITIONAL SHRA/TSRA WERE NOTED OVER CNTRL WI. MUCAPE VALUES TO AROUND 500 J/KG WITH 10C DEWPOINTS IN THE 800-750 MB LAYER...PER TAMDAR SOUNDINGS...WAS ENOUGH TO SUPPORT SOME TSRA WITH BRIEF HEAVY DOWNPOURS. RADAR/SATELLITE TRENDS AND 00Z NAM/RUC ISENTROPIC PROGS SUGGEST THAT THE PCPN BAND WILL CONTINUE TO LIFT ENE EVEN IF ADDITIONAL SHRA/TSRA DEVELOPING ON THE BACK EDGE OF THE BAND SLOW ITS PROGRESS. && .SHORT TERM (TONIGHT AND SUN)... EARLY AFTERNOON WV LOOP SHOWING S/WV THAT WAS OVER MN EARLIER TODAY NOW MOVING INTO NORTHERN WI. REGIONAL RADAR COMPOSITE CONTINUING TO SHOW SCATTERED SHOWERS AND A FEW THUNDERSTORMS MOVING ACROSS THE ARROWHEAD OF MN AND ACROSS CENTRAL WI AHEAD OF THE S/WV. THIS PRECIP WILL CONTINUE TO MOVE INTO A DRIER AIRMASS ACROSS UPPER MI...BUT THE AIRMASS WILL CONTINUE TO MOISTEN OVER TIME. IT APPEARS BEST CHANCE OF RAINFALL ACROSS THE AREA WILL BE DURING THE EVENING HOURS TO SHORTLY AFTER MIDNIGHT. THIS WILL BE THE PERIOD WHEN BEST ISENTROPIC LIFT ALIGNS WITH ADDED LIFT FROM PASSING S/WV. WILL CONTINUE TO TAPER POPS FROM HI CHANCE OVER LAKE SUPERIOR TO NO POPS IN THE SOUTH. AFTER S/WV MOVES THROUGH NOT MUCH IN THE WAY OF FORCING WILL BE LEFT TO SQUEEZE OUT PRECIPITATION AS BEST ISENTROPIC LIFT AND WARM ADVECTION WILL SHIFT NORTHWARD. AFTER MIDNIGHT...HIGHEST POPS WILL BE REFOCUSED OUT WEST CLOSER TO THE MAIN UPPER TROF WHERE ADDITIONAL WEAK S/WV WILL BE RIPPLING NORTHEASTWARD IN FAST SOUTHWESTERLY UPPER FLOW. AS UPPER TROF GETS CLOSER TO THE AREA ON SUNDAY EXPECT POPS TO INCREASE FROM WEST TO EAST THROUGHOUT THE DAY. MOISTURE WILL HAVE INCREASED SIGNIFICANTLY BY THEN WITH PWS IN EXCESS OF 1.5 INCHES. STILL LOOKS LIKE A BREEZY DAY ON SUNDAY WITH 35-40KT AVBL TO BE TAPPED 1-2KFT AGL AS MIXED LAYER BUILDS. THE NCNTRL AND ERN FCST AREA SHOULD BE ESPECIALLY FAVORED FOR WINDY CONDITIONS IN THIS SRLY FLOW SITUATION. HOWEVER...GRADIENT WILL BEGIN TO RELAX DURING THE AFTERNOON AS SURFACE TROF GETS CLOSER. .LONG TERM (SUN NIGHT THROUGH NEXT SAT)... UPPER AIR PATTERN VERY AMPLIFIED TO BEGIN THEN TRANSITIONS TO MORE OF A BROAD TROUGH IN THE WEST AND RIDGE IN THE EAST BY NEXT WEEKEND. TWO SHARP WELL DEFINED UPR LEVEL TROUGHS AFFECT THE UPR GREAT LAKES THE FIRST PART OF THE WEEK. LEADING SYSTEM IS DUE IN SUN NIGHT INTO MON IS WELL AGREED UPON AND SHOULD EXIT LATE MON AFTN/MON EVENING. 00Z ECMWF PREFERRED FOR DETAILS. UPR LOW LIFTS INTO NORTHERN MN BY 00Z MON WITH STRONG S WINDS ON FRONT SIDE OF TROUGH BRINGING UP ABUNDANT MOISTURE AS EVIDENCED BY H85 DEWPOINTS TO +10C AND PWATS NEAR 1.75 INCHES WHICH IS APPROXIMATELY A WHOPPING 250 PCT OF NORMAL. PVA AND H85 CONVERGENCE COMBINES WITH DEEP MOISTURE SOME SLIGHTLY ELEVATED INSTABILITY TO PRODUCE A LIKELY PERIOD OF SHOWERS. AS SYSTEM BEGINS TO OCCLUDE PSEUDO TROF OF WARM AIR ALOFT SHOWS UP LOOKING AT H7 THETA-E. THIS FEATURE WILL DRAG ACROSS THE EAST CWA ON MON SO LINGERING LIKELY POPS OVER THOSE AREAS ON MON MORNING. ONCE UPR LOW DEPARTS...A WEAK SFC TROUGH IS LEFT TO LINGER OVR THE AREA MON NIGHT INTO EARLY TUE. SETUP SEEMS LIKE IT FAVORS SOME FOG AFTER RAIN ENDS MON EVENING. LACK OF MIXING MAY ALLOW THE FOG TO STICK AROUND UNTIL MIXING LATER TUE. SECOND UPR TROUGH FOLLOWS QUICKLY ON THE HEELS OF THE SUN NIGHT AND MON ONE. ECMWF AND CANADIAN PREFERRED AS GFS APPEARS A BIT TOO STRONG. OVERALL THOUGH...GOOD AGREEMENT ON GENERAL IDEA WITH THIS SYSTEM TOO. QUICK MOVEMENT LEADS TO BEST CHANCES OF RAIN TUE NIGHT. 00Z ECMWF INDICATES FRONTAL BOUNDARY TRIGGERING PCPN IS ALREADY THROUGH CWA BY 12Z WED. ENDED PCPN A BIT QUICKER BASED ON LATEST MODEL TRENDS. TO CLOSE THE WEEK...WSW FLOW INCREASES IN RESPONSE TO TROUGH OVER WESTERN CONUS AND EAST COAST RIDGE. H5 HEIGHTS INTO THE 570-575DAM RANGE. HIGHS INTO THE 70S SEEM APPROPRIATE. ENSEMBLE GUIDANCE FOR THU/FRI INDICATES HIGHS IN THE LWR 70S. CONSIDERING THIS GUIDANCE IS BIASED TOWARD CLIMO AND THIS IS A LARGE DEPARTURE FM CLIMO...TEMPS COULD END UP REACHING NEAR 80. 80S CERTAINLY NOT UNHEARD OF FOR THIS TIME OF YEAR AS AN 80 DEGREE OR HIGHER READING HAS BEEN OBSERVED AT THE NWS OFFICE AS LATE AS OCT 17. QUICK GLANCE AT ENSEMBLES AND FAR REACHES OF ECMWF/GFS INDICATE A BRIEF BOUT OF COOLER WEATHER ON THE HORIZON DAYS 7-10. HOWEVER...THERE ARE ALSO INDICATIONS THAT WARMER WEATHER PATTERN SETS UP AGAIN INTO THE MIDDLE OF OCT. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... A BAND OF SHOWERS AND ISOLATED THUNDERSTORMS SUPPORTED BY 40-50 KT INLOW INTO A 850-700 MB WARM FRONT WILL CONTINUE TO LIFT NORTHEAST OUT OF UPPER MICHIGAN OVERNIGHT. LLWS CONDITIONS ARE EXPECTED TO PERSIST DURING THE NIGHT WITH THE PRES GRADIENT REMAINING TIGHT AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM. OTHERWISE...EXPECT VFR CONDITIONS AFTER THE SHRA/TSRA DEPART AFT 06Z. SURFACE HEATING WILL AID MIXING WITH SOUTH WIND GUSTS TO AROUND 25 KT EXPECTED. ADDITIONAL SHRA AND ISOLD TSRA MAY MOVE INTO WEST UPPER MI... INCLUDING KCMX...BY MID TO LATE AFTERNOON AS THE LOW APPROACHES. THE DEFORMATION ZONE PCPN...MODERATE TO HEAVY AT TIMES...WILL SLOWLY EDGE EASTWARD THROUGH WEST INTO CENTRAL UPPER MI WEDNESDAY EVENING WITH MVFR CIGS/VSBYS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FCST ISSUANCE)... S WINDS IN THE 15 TO 25 KT RANGE WILL CONTINUE LATE THIS AFTERNOON AS SFC HIGH MOVES E OF THE AREA AND LOW PRES OVER THE DAKOTAS SHIFTS EAST. WINDS WILL INCREASE A BIT MORE TONIGHT AS INCREASE IN NOCTURNAL LOW LEVEL JET OCCURS. EXPECT WINDS TO 30 KT INTO SUNDAY WITH A FEW GALE FORCE GUSTS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ UPDATE...JLB SHORT TERM...MZ LONG TERM...JLA AVIATION...JLB MARINE...MZ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 325 PM CDT MON OCT 1 2007 .DISCUSSION... UPPER LEVEL TROUGH NOW OFF TO THE EAST CROSSING LAKE MICHIGAN THIS AFTERNOON. LULL IN THE SFC FLOW OVERHEAD WITH MODERATE SOUTHERLY WINDS SETTING UP ACROSS THE DAKOTAS. LOW CLOUD COVER CONTINUES TO WORK SLOWLY EASTWARD AND SHOULD MOVE EAST OF THE TWIN CITIES METRO AND POINTS DUE NORTH AND SOUTH OVER THE NEXT FEW HOURS...WITH COVERAGE REMAINING OVER MUCH OF THE WISCONSIN CWA. SOME PATCHY FOG MAY DEVELOP UNDER AXIS OF WEAK SFC FLOW OVER THE WISCONSIN COUNTIES TONIGHT BEFORE WINDS BECOME SOUTHERLY AND INCREASE. FAST MOVING UPPER TROUGH CROSSING INTO THE WESTERN ROCKIES THIS AFTERNOON WILL SPEED EASTWARD BRINGING SFC LOW PRESSURE CURRENTLY OVER WESTERN SASKATCHEWAN AND ASSOCIATED COLD FRONT WITH IT. FRONT ENTERS WESTERN MINNESOTA AROUND 12Z TUESDAY WITH UPPER WAVE CLOSE ON ITS HEELS. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP AHEAD OF THE FRONT DURING THE MORNING AND RAPIDLY MOVE EASTWARD. ONE LIMITING FACTOR...ESPECIALLY DURING THE MORNING HOURS...WILL BE SPEED OF MOISTURE RETURN AHEAD OF THE FRONT. ACTIVITY MAY BE SOMEWHAT LIMITED DURING THE MORNING BUT IS EXPECTED TO INCREASE BY MIDDAY...OR ACROSS EAST CENTRAL MINNESOTA AND WEST CENTRAL WISCONSIN. INSTABILITY WILL BE LIMITED BUT LAPSE RATES WILL BE STEEP SO WILL NEED TO WATCH FOR MINIMAL HAIL THREAT WITH STRONGER UPDRAFTS. STORMS WILL MOVE SWIFTLY EASTWARD BUT DEEPENING MOISTURE WILL ALLOW FOR HEAVY DOWNPOURS...ESPECIALLY ACROSS FAR EAST CENTRAL MN AND WEST CENTRAL WI. RIDGING QUICKLY FILLS IN BEHIND THE FRONT WEDNESDAY EVENING. MUCH UNCERTAINTY EXISTS REGARDING THE FORECAST FOR THE REMAINDER OF THE WEEK. INDIVIDUAL MODEL SOLUTIONS CONTINUE TO CHANGE SO HAVE LOOKED TO TRENDS IN THEIR SOLUTIONS TO HELP DETERMINE HOW THINGS MAY PAN OUT. ONE THING REMAINS CONSISTENT AND THAT IS THAT MID WEEK ZONAL FLOW WILL BE REPLACED BY AN APPROACHING LONG WAVE TROUGH WHICH INDUCES SFC CYCLOGENESIS ACROSS THE PLAINS. TRENDS OF THE LAST FEW RUNS OF THE GFS AND ECMWF HAVE BEEN TO SLOW THE PROGRESS OF THE UPPER TROUGH...WHEREAS THE TREND SEEN YESTERDAY WAS TO SPEED THINGS UP. MEANWHILE...THE GFS NOW WANTS TO DEVELOP THE WARM FRONT ACROSS CENTRAL MINNESOTA AS EARLY AS THURSDAY MORNING WITH A SURFACE WAVE EJECTING NORTHEAST FROM NEBRASKA FRIDAY MORNING. THIS IS A FAIRLY LARGE CHANGE FROM YESTERDAY. HAVE KEPT THURSDAY DRY FOR NOW WITH POPS INCREASING THURSDAY EVENING AND THURSDAY NIGHT. AS UPPER LOW APPROACHES A SECOND SFC LOW DEVELOPS AND CREATES MORE OF AN INVERTED TROUGH WHICH SETS UP OVER THE AREA FOR SATURDAY. UPPER LOW SLOWLY COMES ACROSS THE UPPER MISSISSIPPI RIVER VALLEY SUNDAY AND CATCHES UP TO SFC TROUGH HELPING IT TO CLOSE OFF AND STRENGTHEN OVER THE UPPER GREAT LAKES. ECMWF A BIT CONSISTENT WITH WAA PASSING OVER FRIDAY WITH WARM AIR IN PLACE INTO SATURDAY WITH PRECIP ARRIVING DURING THE DAY SATURDAY AND LINGERING INTO SUNDAY MORNING...WITH A DRIER FORECAST OVERALL. SATURDAY AFTERNOON THROUGH SATURDAY NIGHT APPEAR TO BE THE BEST TIMES FOR PRECIPITATION...OR AT LEAST THAT IS WHERE THE GREATEST CONFIDENCE LIES. LOW CONFIDENCE IN THE SUNDAY PRECIP FORECAST THOUGH AM THINKING BULK OF THE DAY WILL BE DRY. GFS HAS BEEN WAVERING WITH THE SPEED AT WHICH THE UPPER LOW EXITS AND THUS HOW LONG THE PRECIP STAYS IN THE AREA. MUCH COOLER AIR WILL BE IN PLACE BY THEN AND HIGHS ARE EXPECTED TO BE MUCH BELOW NORMAL IN MANY AREAS WITH HIGHS IN THE MID TO UPPER 50S. ALSO OF NOTE...GFS ENSEMBLE CONFIDENCE GRAPHICS INDICATE INCREASED SPREAD AMONG MEMBERS WITH RECENT RUNS AND THUS LOWER CONFIDENCE FOR THE WEEKEND. THE UPPER LOW CUTS OFF SOMEWHERE OVER THE LOWER GREAT LAKES OR OHIO VALLEY EARLY NEXT WEEK WITH MODEL DIFFERENCES CONTINUING. && .AVIATION... CONCERNS FOR THE VALID TAF PERIOD REVOLVE AROUND LO STRATOCU DECK WITH PRIMARILY MVFR CIGS THAT HAS REMAINED OVR THE ERN 3 TAF SITES...MSP/RNH/EAU...THRU THE DAY. ERN EDGE EXTENDS FROM ABOUT CBG TO THE WRN SIDES OF THE TWIN CITIES TO W OF AEL...AND THE EWRD MOVEMENT SHUD SLOW DOWN AS DAYTIME MIXING SLOWS WITH SUNSET. LATEST RUC PROGS SHOW THAT THE LO CLDS COULD HANG AROUND EAU AND MAYBE RNH FOR AWHILE THIS EVE...ALTHO MSP SHUD BREAK OUT LATE THIS AFTN OR EARLY THIS EVE. WITH LO LVL MSTR AND LGT WINDS FROM THE PROXIMITY OF THE SFC RDG IN THE EAU VICINITY...FOG MAY BECOME AN ISSUE TOWARD SUNRISE. OTHERWISE...THE NEXT ISSUE BECOMES SHRA/TSRA ALNG THE APPROACHING CDFNT TOMORROW. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MDB/KAT mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 1027 AM CDT SUN SEP 30 2007 .DISCUSSION... 12Z UPPR AIR ANLYS INDCD CLOSED H5 LO OVR NE CO ASSOCIATED WITH 70 TO 80 M HEIGHT FALLS ACRS THE WRN HI PLAINS. AT H3 100 KT JET EXTNDD FM SE CO INTO WRN NEB. OAX CWA WAS CURRENTLY RIGHT IN THE MIDDLE OF THE ELEVATED MIXED LAYER WITH +10 AT H7..BUT UPSTREAM COOLING WAS NOTED AT KLBF AND KBOU. AT H85...LO WAS CENTERED NR KLBF WITH THE MOIST AXIS FM THE SRN PLAINS INTO CNTRL NEB WITH +15 C DEW POINTS. 15Z SFC ANLYS INDCD 1005 MB LO OVR KGRI WITH SFC DRY LINE MIXING THRU CNTRL KS AND THE CDFNT MOVING INTO OUR NW CWA. CURRENT TSRA ACTIVITY FM SE NEB INTO WRN IA SHLD CONT TO MOV OFF TO THE E THIS AFTN AND IS BASED ABOVE THE EML OR ARND 700 MB. MORE IMPORTANTLY...SFC LO OVR CNTRL NEB IS EXPECTED TO CONT TO TRACK EWD INTO WEST CENTRAL IA BY MID AFTERNOON. SFC DRY LINE IS EXPECTED TO MIX EAST QUICKLY INTO SW IA. THIS SETS UP AN INTERESTING CORRIDOR OF POSSIBLE SEVERE WEATHER OVER NORTHEAST NEBRASKA INTO WEST CENTRAL IA...JUST TO THE EAST OF THE SFC LO AND JUST SOUTH OF THE ADVANCING COLD FRONT. IN THIS AREA...WHERE SOME PARTIAL CLEANING IS TAKING PLACE...CAPE VALUES OF UP TO 1000 J/KG ARE EXPECTED BY EARLY AFTN. AS LARGE SCALE FORCING...SEEN WELL IN THE 500 TO 300 MB DIV-Q ADVANCING EWD THIS AFTN ASSOCIATED WITH THE UPPER LO...LARGE-SCALE FORCING FOR ASCENT IS EXPECTED TO SIG INCREASE. THUNDERSTORMS ARE EXPECTED TO DEVELOP AND THEN INCREASE IN COVERAGE OVR NE NEB ARND OR SHORTLY AFTER 18Z AND THEN TRACK EWD INTO WEST CENTRAL IA. DEEP-LAYER SHEAR IS VERY FAVORABLE FOR SUPERCELLS IN THIS AREA. LO LVL SHEAR IS STRONG...BUT LITTLE DEEPENING OF THE SFC LO IS EXPECTED THRU THE AFTN AND SFC WINDS ARE EXPECTED TO VEER TO THE SSW AS THE SYSTEM NEARS. THUS LO LVL TURNING WITHIN THE HODOGRAPH IS MARGINAL. NEVERTHELESS...THE LO LVL BULK SHEAR VALUES OF IMPRESSIVE AND THUS CAN NOT RULE OUT AN ISOLATED TORNADO...BUT EXPECTED WIND TO BE THE MAIN THREAT. RELATIVELY WARM MID LVL TMPS...AND A SKINNY AND LONG CAPE PROFILE WILL LIKELY KEEP VERY LARGE HAIL THREAT AT A MINIMUM. FARTHER SOUTH ALONG THE DRY LINE STORMS MAY STRONGER FOR A LONGER TIME GETTING GOING DUE TO THE LACK OF STRONG SURFACE CONVERGENCE WITH THE SOUTHWEST WINDS. THUS BETTER COVERAGE OF STORMS IS EXPECTED ALONG THE DRY LINE FARTHER EAST INTO IA/MO. DID UPDATE THE FORECAST EARLIER TO REDUCE POPS OVR THE WRN CWA THRU THE MRNG...BUT OTHERWISE GOING FORECAST SEEMS IN GOOD SHAPE. POST DRY LINE WINDS OVR THE SW CWA SHLD GET CLOSE OR MEET ADVISORY CRITERIA AND THUS WL KEEP CURRENT ADVRY GOING FOR THAT AREA. BOUSTEAD && .PREV DISCUSSION... /ISSUED 446 AM CDT SUN SEP 30 2007/ DISCUSSION... WILL FOCUS ON SHORT TERM CONCERNS WITH WX ASSOCIATED WITH INTENSE CLOSED MID TROPOSPHERIC LOW PRESSURE SYSTEM AND IF HEADLINES ARE NEEDED. THE LATEST RUC ANALYSIS HAD THE CLOSED MID TROPOSHPERIC LOW OVR NW CO WITH SOME SHORTWAVE TROF ENERGY LIFTING N INTO SD. THE TSRA ARE MOST ACTIVE ACRS SD...HOWEVER EXTEND SW ACRS PARTS OF NEB INTO NW KS...THE OK PNHLD...AND TO ERN NM. THE LEADING EDGE OF THE DEEPER MOISTURE IS NOSING INTO SD AND EXTENDS S IN THE SAME AREA AS WHERE THE TSRA ARE. PER THE H7 ANALYSIS...THERE ARE ELEVATED STEEP LAPSE RATE ALONG WITH GOOD 0-3KM HELICITY ACRS NE NEB. THE INTENSE MID LEVEL LOW OVER CO WILL TRACK ACROSS NEBRASKA TODAY AND INTO IOWA TONIGHT. AHEAD OF IT...THE NLGN1 PROFILER HAD H85 SW WINDS AT 45 KTS AND THE RWDN1/HVLK1 PROFILERS HAD 55KT LOW LEVEL WINDS. SPC HAS THE SLIGHT RISK FOR SVR STORMS MAINLY OVR IA INTO MO AND ERN KS TODAY. THE BETTER THETA-E ADVECTION IS TO OUR EAST...HOWEVER STEEP LAPSE RATES ARE STILL FCST OVR THE ERN PART OF NEB INTO IA AT 18Z AND THE RUC IS SHOWING SOME INTENSE CONVECTION INITIATING OVR ERN NEB EARLY IN THE AFTERNOON. THE SFC LOW AND ASSOCIATED DRYLINE/FNT QUICKLY MOVE ACRS THE AREA THIS AFTERNOON...THUS CONSIDERATIONS FOR SVR WX AND HIGH WINDS. AHEAD OF THE LOW THERE SHOULD BE STRONG MIXING AND BEHIND THE LOW STRONG NW WINDS. DECIDED TO ISSUE A WIND ADVISORY FOR SOUTHEAST NEB FOR MARGINAL WIND ADVISORY CRITERIA WITH THE THOUGHT THAT THE DAY SHIFT COULD EVALUATE HOW MIXING CONDITIONS WERE EVOLVING AND ADD TO OR TRIM AS NECESSARY. DUE TO THE STRONG DYNAMICS AND STRONG WIND SHEAR...ALTHOUGH THE INSTABILITY IS MODEST...COULD SEE STRONG TO SEVERE STORMS IN ERN NEB AND SW IA. CLOUDCOVER AND TEMPERATURES WILL BE A CHALLENGE WITH ONGOING PRECIPITATION NORTH AND HOW MUCH WARM AIR WORKS INTO THE SOUTH BEFORE THE STORM SYSTEM MOVES THROUGH TODAY. HAVE A RANGE OF HIGHS FM THE UPR 60S N TODAY TO THE LOWER 80S SE AND ALSO HAVE HIGH CHC OF TSRA N TODAY WITH A CHC S. THERE MAY BE SOME LINGERING EVENING SHOWERS NORTHEAST...OTHERWISE EXPECT CLEARING AND DIMINISHING NW WINDS OVERNIGHT. MONDAY...HIGH PRES OVR THE PLAINS WILL GIVE WAY TO ANOTHER AREA OF LOW PRES DEVELOPING ACROSS THE WESTERN PLAINS. A MID LEVEL TROF WITH EMBEDDED SHORT WAVES WILL ADVANCE ACRS THE NRN PLNS MON NIGHT AND THE FORECAST AREA MAINLY AFTER 06Z MONDAY NIGHT AND TUESDAY. THE MID LEVEL FLOW FLATTENS OUT WITH DRY CONDITIONS TUESDAY NIGHT THRU WED NIGHT. THE FLOW BECOMES MORE SW AND MORE ACTIVE THU...WITH SHORT WAVE ENERGY MOVING FM SW TO NE IN THE FLOW...WHILE THE MAIN TROF REMAINS OVR THE WRN U.S. THE CDFNT PUSHES ACRS THE CWA SAT AND BOTH THE GFS/ECMWF ARE IN GOOD AGREEMENT WITH THIS. DID NOT MAKE ANY SIG CHGS TO THE EXTENDED AT THIS TIME...HOWEVER THERE MAY BE SOME TWEAKING OF POPS THU AND INCREASING THE CHC FOR RAIN WITH THE FRONT SAT. MON THRU FRI REMAIN MILD WITH ABOVE NORMAL TEMPERATURES. WE GO AT OR BELOW NORMAL WITH THE FROPA SAT. AVIATION... THUNDERSTORMS WEST OF A KOLU TO KOFK LINE WILL LIKELY IMPACT KOFK BTWN 07-09Z AND THEN AGAIN IN ADDITION WITH THE OTHER TAF SITES AFTER 15Z. STRONG S SFC WINDS WL CONT OVR TAF SITES THRU THE EARLY MORNING HOURS WITH SPEEDS OF 20-25 KTS WITH GUSTS TO NEAR 30 KTS. PRECIPITATION WILL PERSIST THROUGH THE EARLY MORNING HOURS. A COLD FRONTAL PASSAGE WILL SHIFT TO THE NORTHWEST THIS AFTERNOON AND THE STRONG GUSTY SOUTH WINDS WILL BE REPLACED WITH GUSTY WEST NORTHWEST UNTIL SUNSET. CZ/JR && .OAX WATCHES/WARNINGS/ADVISORIES... NE...WIND ADVISORY UNTIL 6 PM CDT THIS AFTERNOON FOR NEZ065>068-078- 088>093. IA...NONE. && $$ ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 446 AM CDT SUN SEP 30 2007 .DISCUSSION... WILL FOCUS ON SHORT TERM CONCERNS WITH WX ASSOCIATED WITH INTENSE CLOSED MID TROPOSPHERIC LOW PRESSURE SYSTEM AND IF HEADLINES ARE NEEDED. THE LATEST RUC ANALYSIS HAD THE CLOSED MID TROPOSHPERIC LOW OVR NW CO WITH SOME SHORTWAVE TROF ENERGY LIFTING N INTO SD. THE TSRA ARE MOST ACTIVE ACRS SD...HOWEVER EXTEND SW ACRS PARTS OF NEB INTO NW KS...THE OK PNHLD...AND TO ERN NM. THE LEADING EDGE OF THE DEEPER MOISTURE IS NOSING INTO SD AND EXTENDS S IN THE SAME AREA AS WHERE THE TSRA ARE. PER THE H7 ANALYSIS...THERE ARE ELEVATED STEEP LAPSE RATE ALONG WITH GOOD 0-3KM HELICITY ACRS NE NEB. THE INTENSE MID LEVEL LOW OVER CO WILL TRACK ACROSS NEBRASKA TODAY AND INTO IOWA TONIGHT. AHEAD OF IT...THE NLGN1 PROFILER HAD H85 SW WINDS AT 45 KTS AND THE RWDN1/HVLK1 PROFILERS HAD 55KT LOW LEVEL WINDS. SPC HAS THE SLIGHT RISK FOR SVR STORMS MAINLY OVR IA INTO MO AND ERN KS TODAY. THE BETTER THETA-E ADVECTION IS TO OUR EAST...HOWEVER STEEP LAPSE RATES ARE STILL FCST OVR THE ERN PART OF NEB INTO IA AT 18Z AND THE RUC IS SHOWING SOME INTENSE CONVECTION INITIATING OVR ERN NEB EARLY IN THE AFTERNOON. THE SFC LOW AND ASSOCIATED DRYLINE/FNT QUICKLY MOVE ACRS THE AREA THIS AFTERNOON...THUS CONSIDERATIONS FOR SVR WX AND HIGH WINDS. AHEAD OF THE LOW THERE SHOULD BE STRONG MIXING AND BEHIND THE LOW STRONG NW WINDS. DECIDED TO ISSUE A WIND ADVISORY FOR SOUTHEAST NEB FOR MARGINAL WIND ADVISORY CRITERIA WITH THE THOUGHT THAT THE DAY SHIFT COULD EVALUATE HOW MIXING CONDITIONS WERE EVOLVING AND ADD TO OR TRIM AS NECESSARY. DUE TO THE STRONG DYNAMICS AND STRONG WIND SHEAR...ALTHOUGH THE INSTABILITY IS MODEST...COULD SEE STRONG TO SEVERE STORMS IN ERN NEB AND SW IA. CLOUDCOVER AND TEMPERATURES WILL BE A CHALLENGE WITH ONGOING PRECIPITATION NORTH AND HOW MUCH WARM AIR WORKS INTO THE SOUTH BEFORE THE STORM SYSTEM MOVES THROUGH TODAY. HAVE A RANGE OF HIGHS FM THE UPR 60S N TODAY TO THE LOWER 80S SE AND ALSO HAVE HIGH CHC OF TSRA N TODAY WITH A CHC S. THERE MAY BE SOME LINGERING EVENING SHOWERS NORTHEAST...OTHERWISE EXPECT CLEARING AND DIMINISHING NW WINDS OVERNIGHT. MONDAY...HIGH PRES OVR THE PLAINS WILL GIVE WAY TO ANOTHER AREA OF LOW PRES DEVELOPING ACROSS THE WESTERN PLAINS. A MID LEVEL TROF WITH EMBEDDED SHORT WAVES WILL ADVANCE ACRS THE NRN PLNS MON NIGHT AND THE FORECAST AREA MAINLY AFTER 06Z MONDAY NIGHT AND TUESDAY. THE MID LEVEL FLOW FLATTENS OUT WITH DRY CONDITIONS TUESDAY NIGHT THRU WED NIGHT. THE FLOW BECOMES MORE SW AND MORE ACTIVE THU...WITH SHORT WAVE ENERGY MOVING FM SW TO NE IN THE FLOW...WHILE THE MAIN TROF REMAINS OVR THE WRN U.S. THE CDFNT PUSHES ACRS THE CWA SAT AND BOTH THE GFS/ECMWF ARE IN GOOD AGREEMENT WITH THIS. DID NOT MAKE ANY SIG CHGS TO THE EXTENDED AT THIS TIME...HOWEVER THERE MAY BE SOME TWEAKING OF POPS THU AND INCREASING THE CHC FOR RAIN WITH THE FRONT SAT. MON THRU FRI REMAIN MILD WITH ABOVE NORMAL TEMPERATURES. WE GO AT OR BELOW NORMAL WITH THE FROPA SAT. && .AVIATION... THUNDERSTORMS WEST OF A KOLU TO KOFK LINE WILL LIKELY IMPACT KOFK BTWN 07-09Z AND THEN AGAIN IN ADDITION WITH THE OTHER TAF SITES AFTER 15Z. STRONG S SFC WINDS WL CONT OVR TAF SITES THRU THE EARLY MORNING HOURS WITH SPEEDS OF 20-25 KTS WITH GUSTS TO NEAR 30 KTS. PRECIPITATION WILL PERSIST THROUGH THE EARLY MORNING HOURS. A COLD FRONTAL PASSAGE WILL SHIFT TO THE NORTHWEST THIS AFTERNOON AND THE STRONG GUSTY SOUTH WINDS WILL BE REPLACED WITH GUSTY WEST NORTHWEST UNTIL SUNSET. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...WIND ADVISORY FROM 11 AM THIS MORNING TO 6 PM CDT THIS AFTERNOON FOR NEZ065>068-078-088>093. IA...NONE. && $$ ZAPOTOCNY/REESE ne AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE ALBUQUERQUE NM 938 PM MDT MON OCT 1 2007 .UPDATE...QUICK ZFP UPDATE TO ADJUST OVERNIGHT LOW TEMPS SLIGHTLY AND REMOVE MENTION OF HEAVY RAIN. CLEARING OBSERVED JUST TO WEST OF KFMN...WITH BEST CONVECTION NOTED ALONG FRONTAL BOUNDARY DRAPED ACROSS EASTERN AND SOUTHERN UT. LOWER DEWPOINTS MAY NOT REACH NEW MEXICO UNTIL VERY LATE NIGHT OR TUESDAY. && .PREV DISCUSSION 300 PM MDT MON OCT 1 2007... FORECAST CHALLENGES IN THE SHORT TERM CONCERN PCPN CHANCES...TEMPS AS WELL AS LOW CLOUD/FOG DEVELOPMENT TOWARD DAYBREAK. HIGH PRESSURE TO THE EAST COUPLED WITH AN ADVANCING TROUGH MOVING INTO THE GREAT BASIN HAS ALLOW ABUNDANT MID/UPPER LEVEL MOISTURE TO ADVECT THROUGH THE DESERT SOUTHWEST. SFC DEWPOINTS WERE RELATIVELY LOW EARLY THIS MORNING...HOWEVER SLY LOW LEVEL FLOW IN COMBINATION WITH A TOP-DOWN EFFECT HAS ALLOWED VALUES TO CLIMB INTO THE UPPER 40S/LOW 50S ALONG THE CONTINENTAL DIVIDE WITH 60S OVER THE ERN PLAINS. RUC40 ANALYSIS HAS A NOTABLY STRONG VORT MAX MOVING NE FROM THE UPPER GILA TOWARD THE RIO GRANDE VALLEY. ONLY A FEW LIGHTNING STRIKES ARE NOTED OVER NM ATTM AS BEST DYNAMICS AND INSTABILITY ARE POSITIONED OVER NRN AZ ASSOCIATED WITH A 110KT+ UPPER LEVEL JET AS WELL AS THE ERN PLAINS WHERE A 345-350K THETA-E RIDGE AXIS IS LOCATED. LOCALLY HEAVY RAINS ARE POSSIBLE FROM TRAINING EFFECTS AND FROM STRONG CONVECTION THAT MAY DEVELOP. DECIDED TO TWEAK POP GRIDS TOWARD THE MET GUIDANCE FOR THE EVENING HOURS...WHICH INCLUDE THE LIKELY CATEGORY. TROUGH AXIS IS PROGGED TO ENTER THE FOUR CORNERS REGION BY MIDNIGHT...WHICH MAY INCREASE VERTICAL ASCENT AND PROVIDE THE FINAL THREAT FOR PCPN. THE GFS IS FASTER WITH THE TROUGH PASSAGE...WHICH WOULD ALLOW CLEARING SKIES TO DEVELOP TOWARD DAYBREAK OVER THE W. A LOW LEVEL INVERSION CAN BE EXPECTED DUE TO RADIATIONAL COOLING IF SKIES BECOME CLEAR IN THE WRN VALLEYS...WHICH WILL ALLOW FOR PATCHY FOG TO DEVELOP. LINGERING PCPN CAN BE EXPECTED THROUGH MID-MORNING ACROSS THE CWFA AS TROUGH AXIS SWINGS ACROSS THE REGION. THIS SYSTEM WILL ALSO DRAG A SURFACE BOUNDARY THROUGH THE ERN PLAINS LATE TUESDAY MORNING THRU THE AFTERNOON HOURS. DRIER NW FLOW WILL DEVELOP IN THE WAKE OF THE TROUGH...WHICH MAY BE GUSTY AT TIMES OVER THE NW PLATEAU AS WELL AS THE RIO GRANDE VALLEY. MOS GUIDANCE DIFFER ON MAX TEMPS...BUT SIDED WITH THE COOLER MET WHICH IS MORE PLAUSIBLE FOR EARLY OCTOBER. LESS ACTIVE FOR WEDNESDAY...HOWEVER MOST MODELS ARE SUGGESTING THAT SOME LINGERING MOISTURE WILL PERSIST OVER THE SRN TIER OF NM. 850-500MB LAPSE RATES MAY BE SUFFICIENT ENOUGH TO ALLOW AN ISOLATED STORM TO DEVELOP OVER THE HIGH TERRAIN WED/THU AFTERNOON/EARLY EVENING. SOME OF THE ACTIVITY MAY BE ENHANCED WITH WEAK PERTURBATIONS WITHIN THE UPPER LEVEL W/SW FLOW. ANOTHER TROUGH IS ADVERTISED TO SWING ACROSS THE NRN ROCKIES LATE IN THE WORK WEEK. APPEARS TO BE A GLANCING HIT TO THE NRN ZONES...WITH BREEZY/WINDY CONDITIONS POSSIBLE ELSEWHERE. A SURFACE BOUNDARY SHOULD PUSH THROUGH THE ERN PLAINS ON SATURDAY... WHICH MAY ALLOW FOR SOME OF THE COLDEST READINGS SO FAR THIS SEASON ACROSS THE EAST. INHERITED TEMPS NEAR FREEZING WITHIN THE NE PLAINS LOOKS REASONABLE ATTM. DPORTER && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 46 72 41 79 / 50 5 0 0 GALLUP.......................... 39 74 35 78 / 60 5 0 10 GRANTS.......................... 40 74 38 78 / 80 10 0 10 GLENWOOD........................ 52 81 49 83 / 70 20 10 10 CHAMA........................... 38 68 31 71 / 70 10 0 0 LOS ALAMOS...................... 44 70 39 74 / 80 10 0 0 RED RIVER....................... 37 63 31 67 / 80 10 0 0 TAOS............................ 42 71 33 76 / 70 10 0 0 SANTA FE........................ 45 72 41 76 / 80 10 0 0 SANTA FE AIRPORT................ 46 74 43 78 / 80 10 0 0 ESPANOLA........................ 44 76 39 80 / 70 10 0 0 ALBUQUERQUE HEIGHTS............. 52 75 53 80 / 80 10 0 5 ALBUQUERQUE VALLEY.............. 49 76 47 81 / 80 10 0 5 ALBUQUERQUE FOOTHILLS........... 50 74 51 79 / 80 10 0 0 ALBUQUERQUE WEST MESA........... 51 75 52 80 / 80 10 0 0 SOCORRO......................... 51 79 51 83 / 80 20 0 5 SANDIA PARK/CEDAR CREST......... 44 71 41 75 / 80 20 0 0 MORIARTY/ESTANCIA............... 46 74 40 77 / 80 20 0 5 CARRIZOZO....................... 52 80 52 82 / 70 20 0 5 RUIDOSO......................... 48 73 48 75 / 60 20 0 10 RATON........................... 44 77 39 79 / 40 5 0 0 LAS VEGAS....................... 46 74 42 78 / 70 10 0 0 ROY............................. 52 78 49 79 / 60 5 0 0 CLAYTON......................... 54 80 48 80 / 50 5 0 0 SANTA ROSA...................... 57 84 50 85 / 70 10 0 5 TUCUMCARI....................... 59 86 52 84 / 70 10 0 0 FORT SUMNER..................... 59 85 53 86 / 60 10 0 5 CLOVIS.......................... 58 84 57 84 / 40 10 0 0 PORTALES........................ 57 85 56 85 / 30 20 0 0 ROSWELL......................... 61 88 59 88 / 30 10 0 0 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 46 nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 300 PM MDT MON OCT 1 2007 .DISCUSSION... FORECAST CHALLENGES IN THE SHORT TERM CONCERN PCPN CHANCES...TEMPS AS WELL AS LOW CLOUD/FOG DEVELOPMENT TOWARD DAYBREAK. HIGH PRESSURE TO THE EAST COUPLED WITH AN ADVANCING TROUGH MOVING INTO THE GREAT BASIN HAS ALLOW ABUNDANT MID/UPPER LEVEL MOISTURE TO ADVECT THROUGH THE DESERT SOUTHWEST. SFC DEWPOINTS WERE RELATIVELY LOW EARLY THIS MORNING...HOWEVER SLY LOW LEVEL FLOW IN COMBINATION WITH A TOP-DOWN EFFECT HAS ALLOWED VALUES TO CLIMB INTO THE UPPER 40S/LOW 50S ALONG THE CONTINENTAL DIVIDE WITH 60S OVER THE ERN PLAINS. RUC40 ANALYSIS HAS A NOTABLY STRONG VORT MAX MOVING NE FROM THE UPPER GILA TOWARD THE RIO GRANDE VALLEY. ONLY A FEW LIGHTNING STRIKES ARE NOTED OVER NM ATTM AS BEST DYNAMICS AND INSTABILITY ARE POSITIONED OVER NRN AZ ASSOCIATED WITH A 110KT+ UPPER LEVEL JET AS WELL AS THE ERN PLAINS WHERE A 345-350K THETA-E RIDGE AXIS IS LOCATED. LOCALLY HEAVY RAINS ARE POSSIBLE FROM TRAINING EFFECTS AND FROM STRONG CONVECTION THAT MAY DEVELOP. DECIDED TO TWEAK POP GRIDS TOWARD THE MET GUIDANCE FOR THE EVENING HOURS...WHICH INCLUDE THE LIKELY CATEGORY. TROUGH AXIS IS PROGGED TO ENTER THE FOUR CORNERS REGION BY MIDNIGHT...WHICH MAY INCREASE VERTICAL ASCENT AND PROVIDE THE FINAL THREAT FOR PCPN. THE GFS IS FASTER WITH THE TROUGH PASSAGE...WHICH WOULD ALLOW CLEARING SKIES TO DEVELOP TOWARD DAYBREAK OVER THE W. A LOW LEVEL INVERSION CAN BE EXPECTED DUE TO RADIATIONAL COOLING IF SKIES BECOME CLEAR IN THE WRN VALLEYS...WHICH WILL ALLOW FOR PATCHY FOG TO DEVELOP. LINGERING PCPN CAN BE EXPECTED THROUGH MID-MORNING ACROSS THE CWFA AS TROUGH AXIS SWINGS ACROSS THE REGION. THIS SYSTEM WILL ALSO DRAG A SURFACE BOUNDARY THROUGH THE ERN PLAINS LATE TUESDAY MORNING THRU THE AFTERNOON HOURS. DRIER NW FLOW WILL DEVELOP IN THE WAKE OF THE TROUGH...WHICH MAY BE GUSTY AT TIMES OVER THE NW PLATEAU AS WELL AS THE RIO GRANDE VALLEY. MOS GUIDANCE DIFFER ON MAX TEMPS...BUT SIDED WITH THE COOLER MET WHICH IS MORE PLAUSIBLE FOR EARLY OCTOBER. LESS ACTIVE FOR WEDNESDAY...HOWEVER MOST MODELS ARE SUGGESTING THAT SOME LINGERING MOISTURE WILL PERSIST OVER THE SRN TIER OF NM. 850-500MB LAPSE RATES MAY BE SUFFICIENT ENOUGH TO ALLOW AN ISOLATED STORM TO DEVELOP OVER THE HIGH TERRAIN WED/THU AFTERNOON/EARLY EVENING. SOME OF THE ACTIVITY MAY BE ENHANCED WITH WEAK PERTURBATIONS WITHIN THE UPPER LEVEL W/SW FLOW. ANOTHER TROUGH IS ADVERTISED TO SWING ACROSS THE NRN ROCKIES LATE IN THE WORK WEEK. APPEARS TO BE A GLANCING HIT TO THE NRN ZONES...WITH BREEZY/WINDY CONDITIONS POSSIBLE ELSEWHERE. A SURFACE BOUNDARY SHOULD PUSH THROUGH THE ERN PLAINS ON SATURDAY... WHICH MAY ALLOW FOR SOME OF THE COLDEST READINGS SO FAR THIS SEASON ACROSS THE EAST. INHERITED TEMPS NEAR FREEZING WITHIN THE NE PLAINS LOOKS REASONABLE ATTM. DPORTER && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 46 72 41 79 / 50 5 0 0 GALLUP.......................... 39 74 35 78 / 60 5 0 10 GRANTS.......................... 40 74 38 78 / 80 10 0 10 GLENWOOD........................ 52 81 49 83 / 70 20 10 10 CHAMA........................... 38 68 31 71 / 70 10 0 0 LOS ALAMOS...................... 44 70 39 74 / 80 10 0 0 RED RIVER....................... 37 63 31 67 / 80 10 0 0 TAOS............................ 42 71 33 76 / 70 10 0 0 SANTA FE........................ 45 72 41 76 / 80 10 0 0 SANTA FE AIRPORT................ 46 74 43 78 / 80 10 0 0 ESPANOLA........................ 44 76 39 80 / 70 10 0 0 ALBUQUERQUE HEIGHTS............. 52 75 53 80 / 80 10 0 5 ALBUQUERQUE VALLEY.............. 49 76 47 81 / 80 10 0 5 ALBUQUERQUE FOOTHILLS........... 50 74 51 79 / 80 10 0 0 ALBUQUERQUE WEST MESA........... 51 75 52 80 / 80 10 0 0 SOCORRO......................... 51 79 51 83 / 80 20 0 5 SANDIA PARK/CEDAR CREST......... 44 71 41 75 / 80 20 0 0 MORIARTY/ESTANCIA............... 46 74 40 77 / 80 20 0 5 CARRIZOZO....................... 52 80 52 82 / 70 20 0 5 RUIDOSO......................... 48 73 48 75 / 60 20 0 10 RATON........................... 44 77 39 79 / 40 5 0 0 LAS VEGAS....................... 46 74 42 78 / 70 10 0 0 ROY............................. 52 78 49 79 / 60 5 0 0 CLAYTON......................... 54 80 48 80 / 50 5 0 0 SANTA ROSA...................... 57 84 50 85 / 70 10 0 5 TUCUMCARI....................... 59 86 52 84 / 70 10 0 0 FORT SUMNER..................... 59 85 53 86 / 60 10 0 5 CLOVIS.......................... 58 84 57 84 / 40 10 0 0 PORTALES........................ 57 85 56 85 / 30 20 0 0 ROSWELL......................... 61 88 59 88 / 30 10 0 0 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 46 nm AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAND FORKS ND 1002 AM CDT SUN SEP 30 2007 .UPDATE...MAIN CHALLENGE TODAY WILL BE TRICKY TEMPERATURE FORECAST AND POPS/WX. WEAK WAVE MOVING THROUGH THE SE FA SHOULD BE NE OF FA BY 18Z. 12Z RUC/NAM SHOW ASSOCIATED WEAK 700MB LOW MOVING TO THE NE AND THROUGH BY 18Z. THUS...THINK WIDESPREAD SHOWERS ACROSS THE SE FA WILL BE GONE BY AFTERNOON. MAIN SHORTWAVE WILL PASS SOUTH OF THE FA THIS AFTERNOON...AND MAY SPREAD SOME SCT SHOWERS ACROSS THE FAR SE FA...BUT NOTHING WIDESPREAD. WILL LOWER POPS FOR THIS AFTERNOON. TEMPERATURES SHOULD SHOW MINIMAL RECOVERY WITH COLD AIR ADVECTION AND CLOUD COVER A MAJORITY OF THE DAY. CURRENT VALUES REASONABLE AND WILL NOT CHANGE. && .AVIATION...JUST GOT SOME HIGH AND MID CLOUDS IN THE FCST AREA NOW. SLIM BAND OF MVFR CIGS LOOKS LIKE IT WILL MOVE INTO THE VALLEY 18Z-21Z TIME PERIOD AND THEN CLEAR OUT THEREAFTER. && .PREV DISCUSSION... /ISSUED 318 AM CDT SUN SEP 30 2007/ SHORT TERM... INCOMING 08Z OBS SHOWS COLD FRONT NR A WINNIPEG-HALLOCK-GRAND FORKS-MAYVILLE-LISBON LINE THEN TO JUST WEST OF ABERDEEN. MAIN PCPN MAKER IS STRONG 500 MB VORT MOVING UP ON EAST SIDE OF UPPER LOW NOW IN COLORADO. THIS VORT WAS MOVING INTO SCNTRL SD AND WITH STRONG UPPER DIFFLUENCE NORTHEAST OF VORT MAX A LARGE AREA OF CONVECTION CONTINUES. SVR THREAT APPEARS MINIMAL DUE TO LOW MUCAPES OF ONLY AROUND 500-800 J/KG. BUT ENOUGH FOR THUNDERSTORMS. AS VORT MAX MOVES NORTHEAST FLOW IN THE 700-850 MB FLOW WILL TURN MORE NORTH-NORTHEAST AND THUS BAND OF THUNDERSTORMS IS LIFTING A BIT MORE NORTH THAN PREVIOUSLY AND COORD WITH WFO BISMARCK WOULD HAVE NRN EDGE OF MAIN RAIN NR A VALLEY CITY-HILLSBORO-RED LAKE FALLS-BAUDETTE LINE THIS MORNING. SCATTERED SHOWERS JUST NORTH OF COMPLEX PER BISMARCK RADARS....BUT RATHER SHARP CUTOFF EXPECTED. OVERALL THESE IDEAS FLOWS WELL FROM PAST MODELS RUNS. VORT WILL QUICKLY MOVE INTO NORTH CENTRAL/NE MN BY 15Z...SO WOULD EXPECT A RATHER QUICK ENDING OF THE THE MAIN RAIN BY LATE MORNING IN ALL BUT THE FAR ERN AREAS. THE SHOWER THREAT WILL END IN MY FAR ERN FCST AREA BY 00Z AND IS A LITTLE FASTER THAN PREVIOUS FCST. TEMPS TODAY KIND OF TRICKY...AREA WEST OF FRONT IN DVL REGION JUST SEEING HIGH CLOUDS...BUT BAND OF STRATOCU DOES EXIST IN ERN MT/WRN ND INTO CANADA AND THIS IS PROGGED TO MOVE INTO THE AREA THIS MORNING AND THEN EXIT THIS AFTN. COLD ADVECTION IS STRONGEST ON NAM AND A BIT WEAKER ON GFS. OVERALL...ATMOSPHERE WOULD SUPPORT LOWER TO MID 60S TODAY... HIGHEST READINGS MAY ACTUALLY BE MORE IN THE MORNING FAR ERN FCST AREA AS COLD FRONT NOT THRU PLACES LIKE WADENA AND PKD TIL NR 18Z. QUICK HIGH PRESSURE RIDGE TO MOVE IN TONIGHT WITH CLEAR SKY AND THIS WILL LAST INTO MUCH OF MONDAY BEFORE NEXT FAST MOVING SHORT WAVE NOW ENTERING THE PAC NORTHWEST MOVES INTO THE CNTRL/NRN PLAINS TUESDAY. WILL SPREAD LOW POPS FOR SHOWERS INTO ERN ND LATE MON NIGHT AND THEN SPREAD POPS INTO MN ON TUESDAY MORNING BEFORE SYSTEM QUICKLY EXISTS BY TUES EVE. MOST OF THE JUICE AND INSTABILITY WITH THIS ONE TO OUR SOUTH SO JUST WENT WITH SHOWERS AS SHOWALTERS WELL ABV ZERO. LONG TERM... LONG TERM DOES LOOK ACTIVE...AS ALL MODELS HAVE AGREED FOR PAST FEW DAYS ON SIGNIFICANT 500 MB TROUGH/UPR LOW TO MOVE INTO THE ROCKIES LATE WEEK AND THEN EAST INTO THE PLAINS OVER THE WEEKEND. THIS WILL SPREAD SHOWERS INTO THE AREA. EXACT STRENGTH OF SFC LOW AND TIMING DETAILS HAVE VARIED FROM RUN TO RUN ON THE GFS AND ECMWF SO ATTM NO NEED TO ALTER CURRENT EXTENDED POPS/WX/TEMPS. DID ADJUST SKY COVER ON SATURDAY AS SKY GRIDS HAD 30 PCT IN THERE FOR DVL REGION. THIS SEEMED LOW FOR STORM TO BE NEARBY SO UPPED THEM. COORD WITH BIS ON THIS. HPC SKY COVER GRIDS WHICH WERE USED CAN BE TOO LOW AT TIMES. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ TG nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 837 PM EDT MON OCT 1 2007 .SYNOPSIS... HIGH PRESSURE BOTH SURFACE AND ALOFT WILL DOMINATE THE WEATHER FOR MOST OF THE REST OF WEEK. A SERIES OF WEAKENING FRONTS WILL APPROACH THE REGION...BUT LOOK TO MAINLY FALL APART BEFORE CAUSING ANY SIGNIFICANT CHANCES FOR RAIN. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... POTENT SHORTWAVE OVR LOWER MICHIGAN ATTM WILL TRACK INTO UPSTATE NY OVERNIGHT. HOWEVER...THIS FEATURE IS WORKING INTO DRIER AIR ASSOCIATED WITH SFC HIGH PRES ALONG THE EAST COAST. THEREFORE...WILL INCLUDE CHC OF SHWRS TONIGHT ONLY ACROSS THE NW MTNS. EAST OF THE ALLEGHENY FRONT MOIST SE FLOW AT LOW LVLS WILL LIKELY RESULT IN MARITIME STRATUS DECK DEVELOPING OVERNIGHT. LATEST RUC BLYR RH SUGGESTS A SOLID LOW CLOUD DECK ALONG AND EAST OF MTNS BY 09Z. GFS/NAM DO SPIT OUT SOME VERY LIGHT AMOUNTS OF PRECIP /DZ/ ON WINDWARD SIDE OF ALLEGHENIES. HOWEVER...MODEL DATA SUGGESTS MOISTURE VERY SHALLOW...SO WILL LEAVE OUT DRIZZLE FOR NOW. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... PROBABLY MORE IN THE WAY OF LOW CLOUDS TO DEAL WITH STARTING THE DAY THAN WE HAVE HAD. AS THE SURFACE HIGH CONTINUES OFFSHORE...WE WILL STAY UNDER AN INCREASINGLY MOIST SOUTHERLY FLOW AND HAVE TO DEAL WITH THE CLOUDS AND MAYBE EVEN PATCHY LIGHT PRECIP TUESDAY. EXPECT SOME MEASURE OF BURNING OFF AND LIFTING AS THE DAY WEARS ON...BUT LOWERING SUN ANGLES WILL BE LESS EFFICIENT AT THE PROCESS SO WE COULD TAKE WELL INTO LATE MORNING OR AFTERNOON BEFORE WE SEE ANY SIGNIFICANT BRIGHTENING. THE INCREASED CLOUD-COVER SHOULD WORK TO MAKE MOST AREAS A FEW DEG COOLER TOMORROW THAN TODAY. AS FAR AS PRECIP IS CONCERNED...SHUD REMAIN LIGHT IF AT ALL. THE NW WILL BE VULNERABLE DUE TO THE APPROACH OF THE SHEARING OUT UPPER SHORTWAVE. THE EASTERN AREAS BEING CLOSEST TO THE MARITIME FLOW WILL BE THE SECOND AREA OF CONCERN. EITHER WAY NOT ENUF RAIN TO MAKE A DIFFERENCE IN THE RECENT DRY SPELL. THE EXPECTED INCREASE IN CLOUD COVER AND SOUTHERLY FLOW WILL SERVE TO PROVIDE A MILDER NIGHT THAN THE LAST COUPLE...LOWS IN MOST PLACES STAYING IN THE 50S. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... LARGE SCALE UPPER TROF OVER THE WESTERN U.S. AND A DOWNSTREAM UPPER RIDGE OVER THE EASTERN U.S. ARE FORECAST TO REMAIN IN PLACE FOR MUCH OF THE PERIOD. THUS...SURFACE HIGH PRESSURE WILL CONTINUE TO DOMINATE THE PATTERN OVER PA THROUGH MUCH OF THE MID TO LATE WEEK PERIOD...WITH ABOVE NORMAL TEMPERATURES. SIGNIFICANT RAINFALL WILL REMAIN TOUGH TO COME BY INTO THE UPCOMING WEEKEND. GUIDANCE IS SUGGESTING THAT ENERGY WILL EJECT EAST FROM THE WEST COAST TROF NEXT WEEKEND POSSIBLY BRINGING A COLD FRONT INTO PA AT THE BEGINNING OF NEXT WEEK. SOUTH TO SOUTHEASTERLY FLOW AROUND THE SFC HIGH WILL INCREASE LOW LEVEL MOISTURE ACROSS THE REGION THROUGH THE WEEK. AT THE LEAST THIS WILL SERVE TO INCREASE HUMIDITIES MAKING A FEW SHOWERS POSSIBLE IF ANY SHORTWAVE ENERGY DOES MOVE ACROSS THE STATE. ADDITIONALLY...PERIODS OF LOW CLOUDS AND DRIZZLE ARE POSSIBLE FROM UPSLOPE FLOW ESPECIALLY OVER THE SE HALF OF THE CWA. WHILE NOT TO PRODUCE SIGNIFICANT PCPN...CLOUD COVER WILL HELP TO KEEP TEMPS A LITTLE CLOSER TO SEASONAL NORMALS. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... MARITIME FLOW IS ALREADY MAKING ITS PRESENCE FELT WITH AN INCREASING FIELD OF STRATOCU THAT IS WORKING WESTWARD FROM THE COASTAL PLAIN. STILL MOST CEILINGS ARE VFR WITH CLOUD BASES AVERAGING 3500-4500`...BUT THESE WILL GRADUALLY LOWER OVERNIGHT. EXPECT MVFR IN MOST AREAS BY LATE EVENING/MIDNIGHT WITH CONDITIONS LOWERING FURTHER TO IFR MAINLY IN THE FORM OF CEILINGS BELOW 1000`. FOG WILL PROB NOT BE AS EXTENSIVE TONIGHT AND EARLY TUESDAY AS CLOUD-COVER WILL RETARD THE BEST OF THE RAD COLLING. WITH LOWER SUN ANGLES...CEILINGS WILL LIFT MORE SLOWLY TUESDAY WITH VFR PROBABLY HOLDING OFF UNTIL LATE MORNING OR AFTERNOON AT MOST TERMINALS. THIS MOIST SOUTHERLY FLOW WILL CONTINUE OVER THE REGION ALL WEEK...SO WE WILL AT LEAST BE DEALING WITH OVERNIGHT AND EARLY MORNING LOW CLOUDS AND FOG CONDITIONS. NO WIDESPREAD HEAVY PRECIP PROSPECTS SEEN AT THIS TIME NOTE...TWB026 AND TWB029 HAVE BEEN DISCONTINUED. && .CLIMATE... SEPTEMBER CLIMATE HIGHLIGHTS FOR MDT AND IPT... MDT... THE MEAN TEMPERATURE FOR THE MONTH OF SEPT WAS 69.7...OR 3.5 DEG ABOVE NORMAL. THE TOTAL PRECIPITATION WAS 4.41 INCHES...OR 0.76 INCHES ABOVE NORMAL. A DAILY PRECIPITATION RECORD WAS BROKEN ON THE 27TH. IPT... THE MEAN TEMPERATURE FOR THE MONTH OF SEPT WAS 66.0...OR 2.9 DEG ABOVE NORMAL. THE TOTAL PRECIPITATION WAS 1.63 INCHES...OR 2.35 INCHES BELOW NORMAL. FOR ADDITIONAL CLIMATE INFORMATION FOR THE MONTH OF SEPT...PLEASE REFERENCE /CLMMDT/ AND /CLMIPT/. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LACORTE NEAR TERM...FITZGERALD SHORT TERM...LACORTE LONG TERM...JUNG/GARTNER AVIATION...LACORTE/MARTIN CLIMATE...LACORTE pa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 1055 AM CDT SUN SEP 30 2007 .UPDATE... SHOWERS WERE LEAVING THE FAR NORTHEAST CWA QUICKLY THIS MORNING WHILE NEW SHOWER/TSRA DEVELOPMENT WAS COMING INTO THE FAR SOUTHERN CWA IN CENTRAL SD. THESE SHOWERS/TSRAS WERE DEVELOPING NORTHEAST THIS MORNING AND MAY AFFECT THE AREA FROM KENNEBEC TO MILLER TO REDFIELD TO BRITTON AND EAST THROUGH THIS AFTERNOON. THE LATEST MODELS ARE NOT BIG ON MORE MEASURABLE RAINFALL THROUGH THIS AFTERNOON IN OUR CWA. AS THE UPPER LOW AND SURFACE LOW PRESSURE AREA MOVE EAST NORTHEAST THROUGH THE AFTERNOON AND EVENING AND DRIER AIR AND SUBSIDENCE MOVES IN BEHIND...IT DOES NOT LOOK VERY FAVORABLE FOR SIGNIFICANT SHOWER DEVELOPMENT INTO OUR EASTERN CWA. THUS...DECREASED POPS THROUGH THIS AFTERNOON ACROSS THE AREA. OTHERWISE...LOW CLOUDS WERE FORMING ACROSS THE EASTERN CWA AND SHOULD REMAIN THROUGH MUCH OF THE AFTERNOON. ALSO...BREEZY/WINDY NORTHWEST WINDS WILL REMAIN THROUGH THE AFTERNOON WITH GOOD MIXING AND A GOOD SURFACE PRESSURE GRADIENT. UPDATED AND MADE SOME CHANGES. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH MONDAY NIGHT THE SHORT TERM IS FOCUSED ON ONGOING PRECIPITATION. THE MOST DEVELOPED ACCORDING TO THE WSR-88D IS ASSOCIATED WITH THE COLD FRONT DRAPED THROUGH THIS AREA. AT 08Z THE FRONT IS JUST WEST OF AN KABR TO KPIR LINE AND MOVING EAST. AT THIS TIME THE NAM AND GFS ARE CLOSE WITH THE UPPER LEVEL H5 CLOSED LOW MOVING ALONG JUST BEHIND THE FRONT. THE GFS IS JUST SLIGHTLY FASTER WITH THIS UPPER FEATURE BUT NOT ENOUGH TO MAKE A BIG DIFFERENCE IN THE FORECAST. CONVECTION IS NOTED BEHIND THE SURFACE FRONT AND AHEAD OF THE UPPER LEVEL LOW AND TROUGH. THE 07Z RUC MODEL SHOWS H85 WIND OF AROUND 45 KNOTS OVER OUR EASTERN AREA WITH THE NOSE OF A 60KT MAX MOVING INTO SOUTHEAST SOUTH DAKOTA. IT ALSO DEPICTS A NORTHWEST JET IN NORTHWESTERN SOUTH DAKOTA OF 43 KTS. BY 18Z THE H85 TROUGH AXIS IS MOVING OUT OF THE STATE TO THE EAST WITH THE H5 TROUGH AXIS JUST WEST OF KABR. IN THE WEATHER GRIDS THE PRECIPITATION WAS TIMED TO THIS UPPER FEATURE AND ENDED BY AROUND 00Z. GFS IS SHOWING MORE HANG BACK WRAP AROUND PRECIPITATION LINGERING IN THE FAR EAST. NAM DOES NOT SHOW THIS. THE GFS IS SHOWING THE BEST H7 LIFT IN WESTERN MINNESOTA TO DECIDED TO END IT AT 00Z. TYPICALLY WE WOULD BE SLOW TO CLEAR WITH LINGERING WRAP AROUND CLOUDS. IN THIS CASE THE MODELS AGREE ON A QUICKLY REBUILDING H5 RIDGE AXIS OVER THIS AREA WITH A SURFACE HIGH OVER COLORADO WITH A SURFACE RIDGE OVER EASTERN SOUTH DAKOTA. SO EXPECT CLOUDS TO BE PUSHED THROUGH QUICKER THAN USUAL. BY NOON MONDAY THE NEXT SURFACE TROUGH IS FORMING IN THE LEE OF THE ROCKIES WITH A STRONG RETURN FLOW. THIS SYSTEM WILL MOVE THROUGH EARLY TUESDAY. .LONG TERM...TUESDAY THROUGH THURSDAY NIGHT THIS PERIOD OPENS WITH THE NEST SURFACE FRONTAL SYSTEM MOVING THROUGH EASTERN SOUTH DAKOTA. UNLIKE THE CURRENT SYSTEM THE UPPER SUPPORT FOR THIS NEXT SYSTEM WILL BE MUCH WEAKER AND THERE WILL NOT BE AS MUCH MOISTURE TO WORK WITH. DID CARRY A MENTION OF RAIN SHOWERS TUESDAY WITH THIS FEATURE. THE CHANCE OF RAIN OR THUNDERSTORMS WILL LARGELY BE EAST OF THIS AREA BY TUESDAY AFTERNOON. UPPER LEVEL FLOW THEN GOES TO FAST WESTERLY UNTIL LATE THURSDAY WHEN SOUTHERLY FLOW ACROSS AN OLD BAROCLINIC ZONE WILL BRING A CHANCE TO THE EAST PART OF THE AREA. && .AVIATION... A COLD FRONT HAS PUSHED EAST OUT OF THIS FORECAST AREA...AND ALL FOUR TAF LOCATIONS WILL BE CONTENDING WITH COOL AND BREEZY NORTHWEST WINDS THE REMAINDER OF THE DAY. THE COOLER AIR ADVECTING INTO THE REGION IS GENERATING SCATTERED TO BROKEN MVFR CEILINGS ACROSS THE FORECAST AREA /THE EXCEPTION IS OCCASIONAL IFR MIXED WITH THOSE MVFR CIGS AT KATY/. MOST OF THE CONVECTION FROM EARLIER THIS MORNING HAS VACATED TO MINNESOTA AND IOWA. HOWEVER...WSR-88D REFLECTIVITY SCANS ARE BEGINNING TO PIN-POINT NEW CONVECTION DEVELOPING ACROSS SOUTH CENTRAL SOUTH DAKOTA. WHILE ISOLATED TO WIDELY SCATTERED SHOWERS OR THUNDERSTORMS ARE POSSIBLE FOR THE NEXT 3 TO 6 HOURS AT THE KPIR TERMINAL...A HIGHER PROBABILITY EXISTS FOR SHOWER/THUNDERSTORM REDEVELOPMENT OVER THE KATY TERMINAL LATER THIS AFTERNOON. IT IS BECOMING INCREASINGLY LIKELY THAT THE SCATTERED TO BROKEN MVFR CEILINGS WILL HOLD ON LONG ENOUGH TO IMPACT THE KPIR...KABR...AND KATY WELL INTO THIS EVENING BEFORE GRADUAL DISSIPATION AND/OR MOVEMENT SOUTH AND EAST OUT OF THIS FORECAST AREA OVERNIGHT. AMENDMENTS TO FOLLOW ACCORDINGLY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...MOHR SHORT TERM...TMT LONG TERM...KEEFE AVIATION...DORN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 352 AM CDT SUN SEP 30 2007 .SHORT TERM...TODAY THROUGH MONDAY NIGHT THE SHORT TERM IS FOCUSED ON ONGOING PRECIPITATION. THE MOST DEVELOPED ACCORDING TO THE WSR-88D IS ASSOCIATED WITH THE COLD FRONT DRAPED THROUGH THIS AREA. AT 08Z THE FRONT IS JUST WEST OF AN KABR TO KPIR LINE AND MOVING EAST. AT THIS TIME THE NAM AND GFS ARE CLOSE WITH THE UPPER LEVEL H5 CLOSED LOW MOVING ALONG JUST BEHIND THE FRONT. THE GFS IS JUST SLIGHTLY FASTER WITH THIS UPPER FEATURE BUT NOT ENOUGH TO MAKE A BIG DIFFERENCE IN THE FORECAST. CONVECTION IS NOTED BEHIND THE SURFACE FRONT AND AHEAD OF THE UPPER LEVEL LOW AND TROUGH. THE 07Z RUC MODEL SHOWS H85 WIND OF AROUND 45 KNOTS OVER OUR EASTERN AREA WITH THE NOSE OF A 60KT MAX MOVING INTO SOUTHEAST SOUTH DAKOTA. IT ALSO DEPICTS A NORTHWEST JET IN NORTHWESTERN SOUTH DAKOTA OF 43 KTS. BY 18Z THE H85 TROUGH AXIS IS MOVING OUT OF THE STATE TO THE EAST WITH THE H5 TROUGH AXIS JUST WEST OF KABR. IN THE WEATHER GRIDS THE PRECIPITATION WAS TIMED TO THIS UPPER FEATURE AND ENDED BY AROUND 00Z. GFS IS SHOWING MORE HANG BACK WRAP AROUND PRECIPITATION LINGERING IN THE FAR EAST. NAM DOES NOT SHOW THIS. THE GFS IS SHOWING THE BEST H7 LIFT IN WESTERN MINNESOTA TO DECIDED TO END IT AT 00Z. TYPICALLY WE WOULD BE SLOW TO CLEAR WITH LINGERING WRAP AROUND CLOUDS. IN THIS CASE THE MODELS AGREE ON A QUICKLY REBUILDING H5 RIDGE AXIS OVER THIS AREA WITH A SURFACE HIGH OVER COLORADO WITH A SURFACE RIDGE OVER EASTERN SOUTH DAKOTA. SO EXPECT CLOUDS TO BE PUSHED THROUGH QUICKER THAN USUAL. BY NOON MONDAY THE NEXT SURFACE TROUGH IS FORMING IN THE LEE OF THE ROCKIES WITH A STRONG RETURN FLOW. THIS SYSTEM WILL MOVE THROUGH EARLY TUESDAY. .LONG TERM...TUESDAY THROUGH THURSDAY NIGHT THIS PERIOD OPENS WITH THE NEST SURFACE FRONTAL SYSTEM MOVING THROUGH EASTERN SOUTH DAKOTA. UNLIKE THE CURRENT SYSTEM THE UPPER SUPPORT FOR THIS NEXT SYSTEM WILL BE MUCH WEAKER AND THERE WILL NOT BE AS MUCH MOISTURE TO WORK WITH. DID CARRY A MENTION OF RAIN SHOWERS TUESDAY WITH THIS FEATURE. THE CHANCE OF RAIN OR THUNDERSTORMS WILL LARGELY BE EAST OF THIS AREA BY TUESDAY AFTERNOON. UPPER LEVEL FLOW THEN GOES TO FAST WESTERLY UNTIL LATE THURSDAY WHEN SOUTHERLY FLOW ACROSS AN OLD BAROCLINIC ZONE WILL BRING A CHANCE TO THE EAST PART OF THE AREA. && .AVIATION... WSR-88D IS SHOWING WIDESPREAD CONVECTION ACROSS THIS AREA AND MOVING WITH THE COLD FRONT. THIS CONVECTION WILL END IN THE WEST PART OF THE AREA BY AROUND NOON. SHOWERS AND SOME CONVECTION WILL MOVE OUT OF THE AREA BY EARLY EVENING. CEILINGS WILL IMPROVE QUICKLY BEHIND THE COLD FRONT AS WILL VISIBILITY. BY EVENING EXPECT ENTIRE AREA TO BE VFR WITH CEILINGS ABOVE 12K FT AND UNRESTRICTED VISIBILITY. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ SHORT TERM...KEEFE LONG TERM...KEEFE AVIATION...KEEFE sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 952 AM CDT MON OCT 1 2007 .UPDATE...RUC IS ANALYZING AN ELONGATED CYCLONIC VORT MAX DRAPED ACROSS SOUTH CENTRAL TEXAS EXTENDING INTO SE TX. 12Z CRP SOUNDING HAS A PW OF APPROXIMATELY 2 AND A QUARTER INCHES WITH CONDITIONALLY UNSTABLE LOW LEVEL LAPSE RATES AND A 700MB TEMP OF 8C. WITH A MOIST TROPICAL AIR MASS IN PLACE...A CONDITIONALLY UNSTABLE THERMODYNAMIC PROFILE...AND UPPER SUPPORT OVER THE REGION WITH CONVECTION ALREADY DEVELOPING OVER THE INLAND SECTIONS...WENT AHEAD AND KICKED UP FIRST PERIOD POPS AREAWIDE. OTHERWISE...THE REMAINING WEATHER ELEMENTS APPEAR TO BE IN GOOD SHAPE. UPDATED PRODUCTS HAVE BEEN SENT. && .PREV DISCUSSION... /ISSUED 400 AM CDT MON OCT 1 2007/ SHORT TERM (TODAY THROUGH TUESDAY)...MID-LEVEL RIDGING/SYNOPTIC-SCALE SUBSIDENCE TAKES A FIRMER STANCE AS THE TROPOSPHERIC COLUMN GRADUALLY DRIES(WATER VAPOR IMAGERY SUPPORTS NAM/UKMET) THROUGH TUESDAY. UNFAVORABLE SOUTHERLY FLOW AT 850HPA YESTERDAY BECOMES A MORE FAVORABLE SE/E FLOW TODAY WHEN PWATS ARE STILL FAVORABLY HIGH. HOWEVER...FEEL GUIDANCE POPS ARE TOO HIGH GIVEN GENERALLY WEAK FORCING...SO WILL INDICATE 20-30% POPS. NO PRECIPITATION IS EXPECTED TONIGHT/TUESDAY. MOIST GROUND/STABLE BOUNDARY LAYER SUPPORTS AREAS OF FOG ACROSS THE INTERIOR DURING THE OVERNIGHT/EARLY MORNING HOURS. LITTLE TO NO CHANGES TO THE PREVIOUS TEMPERATURE GRIDS. AVIATION...MVFR VSBYS/CIGS WITH AREAS OF LIFR VSBYS/CIGS ARE EXPECTED ACROSS THE INTERIOR UNTIL 14Z. OTHERWISE...SCT-BKN VFR CIGS WILL PREVAIL THROUGH 02Z. VFR CONDITIONS ARE THEN EXPECTED FROM 02Z-09Z. MVFR VSBYS/CIGS WITH AREAS OF LIFR VSBYS/CIGS WILL THEN RETURN ACROSS THE INTERIOR BETWEEN 09Z-12Z. MARINE...WINDS TO REMAIN BELOW HEADLINE CRITERIA WITH ONLY ISOLATED CONVECTION EXPECTED THIS MORNING. LONG TERM (TUESDAY NIGHT THROUGH SUNDAY)...BENIGN WEATHER PATTERN WILL CONTINUE INTO THE EARLY PART OF THE LONG TERM PERIOD AS THE MID/UPPER LEVEL RIDGE AXIS AND DRY AIR WILL REMAIN OVER THE REGION THRU THURSDAY. BUT THE GFS/UKMET/ECMWF SHOW THE TUTT LOW NEAR THE FLORIDA KEYS EARLY THIS MORNING WILL MIGRATE WESTWARD ACROSS THE GULF OF MEXICO TO THE SOUTH OF THE RIDGE AXIS. IT APPEARS THAT SOME TYPE OF HYBRID TROPICAL/SUBTROPICAL SYSTEM COULD DEVELOP OVER THE CENTRAL GULF BY WEDNESDAY/THURSDAY. PREFER TO LEAN TOWARD THE MORE CONSISTENT 00Z ECMWF SOLUTION AT THIS POINT WHICH THE 12Z UKMET WAS NOT TOO FAR OFF IN AGREEMENT WITH MOVING THIS UPPER LOW INTO THE LOWER TO MIDDLE TEXAS COAST BY FRIDAY. THE ECMWF SHOWS THE UPPER LEVEL SHEAR OVER THIS SYSTEM WEAKENING...SO SOME DEVELOPMENT OF A WEAK TROPICAL SYSTEM COULD BE POSSIBLE BY THE END OF THE WEEK. WILL RAISE POPS TO 30/40 PERCENT FRIDAY THROUGH SATURDAY. STILL A LOT OF UNCERTAINTY WITH THIS SYSTEM AS THE GFS WEAKENS IT BY FRIDAY WHILE THE NAM/CANADIAN MODELS SPIN IT UP INTO THE NORTHEASTERN GULF OF MEXICO THURSDAY. THESE SEEM TO OUTLIERS AT THIS POINT. THE GFS AND ECMWF SHOW A STRONG UPPER TROUGH MOVING INTO THE ROCKIES BY FRIDAY THAT WILL HOPEFULLY USHER IN MORE FALL LIKE CONDITIONS OVER SOUTH TEXAS BY THE BEGINNING OF NEXT WEEK. THE GFS IS A BIT FASTER MOVING THE UPPER TROUGH INTO THE PLAINS THAN THE ECMWF AND THEREBY PUSHES A COLD FRONT INTO SOUTH TEXAS BY SUNDAY MORNING. WILL LEAN TOWARD THE SLOWER ECMWF FOR NOW WITH THE FRONT MOVING INTO THE AREA SUNDAY EVENING. MOISTURE AND INSTABILITY WILL BE SUFFICIENT IN ADVANCE OF THE FRONT TO EXPECT A DECENT CHANCE OF RAIN OVER SOUTH TEXAS ON SUNDAY. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 90 72 91 69 91 / 30 10 10 10 10 VICTORIA 90 68 91 67 91 / 40 10 10 10 10 LAREDO 96 74 97 74 97 / 40 10 10 10 10 ALICE 92 70 93 68 94 / 40 10 10 10 10 ROCKPORT 90 74 91 73 90 / 20 10 10 10 10 COTULLA 92 71 93 70 94 / 40 10 10 10 10 KINGSVILLE 91 71 92 68 92 / 30 10 10 10 10 NAVY CORPUS 89 76 90 74 89 / 30 10 10 10 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ TM/95...UPDATE tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 1250 AM CDT MON OCT 1 2007 .AVIATION... A WEAK FRONT IS STILL MOVING SOUTH INTO THE NORTHERN PERMIAN BASIN THIS MORNING. EXPECT MINOR WIND SHIFTS WITH THE PASSAGE LATER THIS MORNING...BUT LIKELY NOT TOO NOTICEABLE WITH SURFACE WINDS STAYING WELL BELOW 10KT. HIGH CLOUD COVER IS PREDOMINANT ON SATELLITE IMAGERY THIS MORNING. THE ONLY LOW CLOUDS ON THE SCOPE ARE CURRENTLY WELL TO THE SOUTHEAST OF THE AREA...CLOSER TO THE KSAT AREA. DO EXPECT THAT LOWER CLOUDS WILL ADVECT TOWARDS THE AREA AND LIKELY BEGIN AFFECTING THE EASTERN TAF SITES /KMAF & KFST/ BY DAYLIGHT AND OTHERS SHORTLY AFTER SUNRISE. DO NOT EXPECT ANY WIDESPREAD VISIBILITY PROBLEMS...AS WINDS WILL LIKELY STAY UP JUST ENOUGH TO KEEP ANY POTENTIAL FOG DEVELOPMENTS FROM OCCURRING. KMAF /MAY/ BE THE EXCEPTION AS WINDS ARE EXPECTED TO REMAIN JUST CALM ENOUGH THROUGH THE EARLY MORNING HOURS TO ALLOW SOME MINOR BR TO DEVELOP...SO HAVE TEMPO/D IN 5SM VIS FOR THIS POSSIBILITY. && .PREV DISCUSSION... /ISSUED 444 PM CDT SUN SEP 30 2007/ .DISCUSSION... FAST MOVING UPPER LOW LIFTING NEWD INTO THE CENTRAL PLAINS WITH ASSOCD COLD FRONT PUSHING INTO S PLAINS. MEANWHILE PROMINENT MID LEVEL RIDGE AXIS IS ESTABLISHED ACRS W TX. NAM SUGGESTS COLD FRONT WILL NEAR NRN CWFA...BUT STRUGGLE TO MAKE IT MUCH FARTHER S AS SFC ANTICYCLONE TENDS TO REMAIN UNDERNEATH SLIGHTLY CONFLUENT NW MID LEVEL FLOW ACRS CENTRAL/SOUTHERN PLAINS. STRONG 3HR MSL PRESSURE RISES ERN CO/WRN KS SUGGEST COLD FRONT WILL BE FARTHER S. HAVE OPTED TO INCORPORATE RUC INTO SHORT TERM PORTION TO REFLECT FRONT FARTHER S. AS FAR AS CONVECTIVE POTENTIAL GOES...MTNS AND VICINITY WILL HAVE BEST CHANCE INTO EARLY EVENING DUE TO LOCATION OF THETA-E RIDGE...POSSIBILITY OF SHRTWV/S FROM THE S...AND AS WRN AREAS ARE FARTHER REMOVED FROM 5H RIDGE AXIS. ISOLD STRONG MULTI- CELL STORMS WILL AGAIN BE POSSIBLE WITH 7H-5H LR/S NEAR 7 C/KM AND 0-6KM SHEAR NEAR 20KTS. IF CONVECTION IS REALIZED ALONG BOUNDARY THEN IT MAY HAVE THE NEEDED PUSH TO MAKE IT INTO PB...OTHERWISE WILL OPT TO KEEP WIND SHIFT N. WRT TO MORNING LOW TEMPS THEY HAVE BEEN TRENDING UPWARD OVER THE LAST 5 MORNINGS. PART OF THIS HAS BEEN DUE TO WINDS STAYING UP OVERNIGHT IN ASSOCN WITH LLJ. ALTHOUGH SFC DWPNTS WILL REMAIN UP (M60S) ACRS PB THE PW/S IN GENERAL WILL DECREASE AND WINDS WILL BE LESS SO WILL GO SLIGHTLY COOLER THAN THIS MORNING...BUT MID TO UPPER 60S ARE STILL WELL ABOVE NORMAL. BY MON P.M. MID LEVEL FLOW WILL BUCKLE ACRS THE GREAT BASIN AS SHRTWV TROF MOVES INTO THE REGION WITH PATTERN SOMEWHAT PROGRESSIVE WITH AFOREMENTIONED RIDGE GETTING PUSHED E WITH WELL ESTABLISHED SW MID LEVEL FLOW ACRS CWFA. THIS SW MID LEVEL FLOW WILL BE ABLE TO TAP PACIFIC MSTR WITH DECENT MSTR FETCH E OF MID LEVEL TROF AXIS. SHRTWV TROF/S IN ADVANCE OF MAIN TROF AXIS WILL BE FAVORED W OF CWFA WHERE STRONGER SW MID LEVEL FLOW WILL BE AND ATTP WILL CONTINUE TO KEEP BEST W MON. AS THIS SYSTEM PROGRESS E TUE THE CHANCE OF RAIN WILL SHIFT E INTO THE PLAINS WITH THETA-E RIDGE OVERHEAD AND SUFFICIENT LIFT PROVIDE BY MID LEVEL TROF. NAM ALSO SUGGEST MODEST LOW LEVEL CONVERGENCE WITH WEAK SFC LOW ACRS SE NM...COLD FRONT IN THE S PLAINS...AND SFC TROF ACRS LOWER TRANS PECOS. CURRENT FCST HAS THIS TREND OF PUSHING HIER POPS E TUE...HOWEVER WILL INCREASE CENTRAL/N PB INTO SCT POPS. PROBABLY COOLER TUE WITH CLOUD COVER. PROGRESSIVE NATURE OF THIS TROF WILL FAVOR COLD FRONT PUSHING S THRU PB BY WED A.M. AND WILL TEND TOWARD DRY FCST N WITH ISOLD/SLGHT CHC POPS S. THUR SW FLOW AT 7H INCREASES TO AROUND 15KTS WITH WELL DEVELOPED LEE TROF. LOW LEVEL MSTR WILL LIKELY STILL HOLD THUR SO ISOLD POPS STILL WARRANTED IN THE HIER TERRAIN. DRY AIR BECOMES APPARENT IN THE MODEL DATA BY FRI P.M. WITH LOW LEVEL THERMAL RIDGE SUGGESTING TEMPS COULD BE WELL ABOVE NORMAL INTO SAT. MEANWHILE 7H WINDS WILL CONTINUE TO INCREASE INTO SAT WITH VERY DRY AIR MAKING EWD AT LEAST INTO SE NM PLAINS AHEAD OF A COLD FRONT. GFS/ECMWF IN GOOD AGREEMENT THAT SHARP 5H TROF AXIS WILL PASS PUSHING COLD FRONT THRU...PROBABLY EARLY SUN. ATTP WILL INCREASE TEMPS SOME FRI/SAT PER 85H TEMPS AND NOTE COOLER WX FOR SUNDAY. && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ 13 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 444 PM CDT SUN SEP 30 2007 .DISCUSSION... FAST MOVING UPPER LOW LIFTING NEWD INTO THE CENTRAL PLAINS WITH ASSOCD COLD FRONT PUSHING INTO S PLAINS. MEANWHILE PROMINENT MID LEVEL RIDGE AXIS IS ESTABLISHED ACRS W TX. NAM SUGGESTS COLD FRONT WILL NEAR NRN CWFA...BUT STRUGGLE TO MAKE IT MUCH FARTHER S AS SFC ANTICYCLONE TENDS TO REMAIN UNDERNEATH SLIGHTLY CONFLUENT NW MID LEVEL FLOW ACRS CENTRAL/SOUTHERN PLAINS. STRONG 3HR MSL PRESSURE RISES ERN CO/WRN KS SUGGEST COLD FRONT WILL BE FARTHER S. HAVE OPTED TO INCORPORATE RUC INTO SHORT TERM PORTION TO REFLECT FRONT FARTHER S. AS FAR AS CONVECTIVE POTENTIAL GOES...MTNS AND VICINITY WILL HAVE BEST CHANCE INTO EARLY EVENING DUE TO LOCATION OF THETA-E RIDGE...POSSIBILITY OF SHRTWV/S FROM THE S...AND AS WRN AREAS ARE FARTHER REMOVED FROM 5H RIDGE AXIS. ISOLD STRONG MULTI- CELL STORMS WILL AGAIN BE POSSIBLE WITH 7H-5H LR/S NEAR 7 C/KM AND 0-6KM SHEAR NEAR 20KTS. IF CONVECTION IS REALIZED ALONG BOUNDARY THEN IT MAY HAVE THE NEEDED PUSH TO MAKE IT INTO PB...OTHERWISE WILL OPT TO KEEP WIND SHIFT N. WRT TO MORNING LOW TEMPS THEY HAVE BEEN TRENDING UPWARD OVER THE LAST 5 MORNINGS. PART OF THIS HAS BEEN DUE TO WINDS STAYING UP OVERNIGHT IN ASSOCN WITH LLJ. ALTHOUGH SFC DWPNTS WILL REMAIN UP (M60S) ACRS PB THE PW/S IN GENERAL WILL DECREASE AND WINDS WILL BE LESS SO WILL GO SLIGHTLY COOLER THAN THIS MORNING...BUT MID TO UPPER 60S ARE STILL WELL ABOVE NORMAL. BY MON P.M. MID LEVEL FLOW WILL BUCKLE ACRS THE GREAT BASIN AS SHRTWV TROF MOVES INTO THE REGION WITH PATTERN SOMEWHAT PROGRESSIVE WITH AFOREMENTIONED RIDGE GETTING PUSHED E WITH WELL ESTABLISHED SW MID LEVEL FLOW ACRS CWFA. THIS SW MID LEVEL FLOW WILL BE ABLE TO TAP PACIFIC MSTR WITH DECENT MSTR FETCH E OF MID LEVEL TROF AXIS. SHRTWV TROF/S IN ADVANCE OF MAIN TROF AXIS WILL BE FAVORED W OF CWFA WHERE STRONGER SW MID LEVEL FLOW WILL BE AND ATTP WILL CONTINUE TO KEEP BEST W MON. AS THIS SYSTEM PROGRESS E TUE THE CHANCE OF RAIN WILL SHIFT E INTO THE PLAINS WITH THETA-E RIDGE OVERHEAD AND SUFFICIENT LIFT PROVIDE BY MID LEVEL TROF. NAM ALSO SUGGEST MODEST LOW LEVEL CONVERGENCE WITH WEAK SFC LOW ACRS SE NM...COLD FRONT IN THE S PLAINS...AND SFC TROF ACRS LOWER TRANS PECOS. CURRENT FCST HAS THIS TREND OF PUSHING HIER POPS E TUE...HOWEVER WILL INCREASE CENTRAL/N PB INTO SCT POPS. PROBABLY COOLER TUE WITH CLOUD COVER. PROGRESSIVE NATURE OF THIS TROF WILL FAVOR COLD FRONT PUSHING S THRU PB BY WED A.M. AND WILL TEND TOWARD DRY FCST N WITH ISOLD/SLGHT CHC POPS S. THUR SW FLOW AT 7H INCREASES TO AROUND 15KTS WITH WELL DEVELOPED LEE TROF. LOW LEVEL MSTR WILL LIKELY STILL HOLD THUR SO ISOLD POPS STILL WARRANTED IN THE HIER TERRAIN. DRY AIR BECOMES APPARENT IN THE MODEL DATA BY FRI P.M. WITH LOW LEVEL THERMAL RIDGE SUGGESTING TEMPS COULD BE WELL ABOVE NORMAL INTO SAT. MEANWHILE 7H WINDS WILL CONTINUE TO INCREASE INTO SAT WITH VERY DRY AIR MAKING EWD AT LEAST INTO SE NM PLAINS AHEAD OF A COLD FRONT. GFS/ECMWF IN GOOD AGREEMENT THAT SHARP 5H TROF AXIS WILL PASS PUSHING COLD FRONT THRU...PROBABLY EARLY SUN. ATTP WILL INCREASE TEMPS SOME FRI/SAT PER 85H TEMPS AND NOTE COOLER WX FOR SUNDAY. && .PRELIMINARY POINT TEMPS/POPS... BIG SPRING TX 69 90 69 86 / 10 10 20 30 CARLSBAD NM 63 86 65 89 / 20 20 20 30 DRYDEN TX 69 89 71 94 / 20 10 20 20 FORT STOCKTON TX 68 90 71 88 / 20 10 20 30 GUADALUPE PASS TX 62 83 62 82 / 20 30 20 20 HOBBS NM 66 87 68 86 / 20 20 20 30 MARFA TX 57 82 59 82 / 20 20 20 20 MIDLAND INTL AIRPORT TX 67 90 68 87 / 10 10 20 30 ODESSA TX 68 91 69 87 / 20 20 20 30 WINK TX 69 95 71 90 / 20 20 20 30 && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CORPUS CHRISTI TX 1038 AM CDT SUN SEP 30 2007 .SHORT TERM...CONVECTION BEING SUPPRESSED ACROSS CWFA THIS MORNING...PERHAPS DUE TO A MIN VORT LOBE SHOWING UP ON RECENT RUC RUNS. HAVE ADJUSTED POPS INLAND TO ACCOUNT FOR THIS SUPPRESSION...ALTHOUGH AFTERNOON HEATING MIGHT BE ENOUGH TO TRIGGER SCATTERED SEABREEZE ACTIVITY THIS AFTERNOON. HIGH TEMPERATURES STILL LOOK REASONABLE DESPITE MORE SUN THAN EXPECTED...SO WILL RETAIN PREVIOUS TEMPERATURE GRIDS. && .PREV DISCUSSION... /ISSUED 401 AM CDT SUN SEP 30 2007/ SHORT TERM (TODAY THROUGH MONDAY)...TROPICAL MOISTURE/INSTABILITY WILL CONTINUE THROUGH TONIGHT AND ONLY SLOWLY DECREASE MONDAY(PER THE FAVORED SLOWER UKMET/NAM SOLUTIONS). SOME DYNAMICAL FORCING WILL EXIST TODAY...OTHERWISE COASTAL CONVERGENCE WILL TRANSITION TO SEA BREEZE BOUNDARY FORCING BOTH DAYS. HIGH-END CHANCE TO LIKELY POPS TODAY WILL LOWER TO MOSTLY CHANCE POPS TONIGHT/MONDAY. SHOWED A TRANSITION TO LOWER POPS EACH AFTERNOON OVER THE EAST AS THE SEA BREEZE BOUNDARY PENETRATES INLAND FASTER THAN YESTERDAY. EXPECT COASTAL WATERSPOUTS TO BE WEAKER TODAY AS A WELL-DEFINED COASTAL TROUGH WILL NOT BE PRESENT. JUST SOME MINOR TWEAKS TO THE PREVIOUS TEMPERATURE GRIDS. AVIATION...MVFR CIGS/VSBYS WITH LOCALIZED IFR CIGS/VSBYS CAN BE EXPECTED UNTIL 15Z...THEN VFR CIGS WILL PREVAIL INTO THE EARLY EVENING. SCATTERED TO NUMEROUS CONVECTION WILL RESULT IN LOW-END MVFR CIGS/VSBYS INTO THE EARLY EVENING. MARINE...SCATTERED CONVECTION DURING THE MORNING HOURS WILL TRANSITION TO ISOLATED CONVECTION DURING THE AFTERNOON/EVENING HOURS. SOME MARGINAL SCEC CONDITIONS ARE POSSIBLE ACROSS THE NEARSHORE/OFFSHORE WATERS THROUGH MONDAY. LONG TERM (MONDAY NIGHT THROUGH SATURDAY)...THE MID LEVEL ANTICYCLONE OVER THE SOUTHEAST UNITED STATES THIS MORNING WILL SLOWLY TRANSLATE TO THE SOUTHWEST BY TUESDAY MORNING. THE MID LEVEL RIDGE AXIS WILL BE OVER THE SOUTH TEXAS REGION ON TUESDAY WITH MUCH DRIER AIR FROM THE NORTHEAST INVADING THE COASTAL BEND. THIS RIDGE AXIS AND DRIER AIR WILL BE IN CONTROL OF THE WEATHER PATTERN FROM TUESDAY UNTIL THURSDAY. REMOVED MENTION OF DIURNAL SLIGHT CHANCE POPS OVER THE COASTAL PLAINS DURING THIS PERIOD AND LOWERED MINIMUM TEMPS. THE GFS/ECMWF/UKMET SHOW A TUTT LOW DEVELOPING OVER THE FLORIDA STRAITS BY MONDAY. THIS SYSTEM WILL SLOWLY MOVE WEST ACROSS THE GULF OF MEXICO AND BE IN THE WESTERN GULF OF MEXICO OFF THE LOWER TEXAS COAST BY THURSDAY EVENING. THE GFS IS A LITTLE LESS ORGANIZED THAN THE ECMWF BY FRIDAY AND FOR NOW WILL LEAN TOWARD THE GFS SOLUTION. WILL INTRODUCE POPS ALONG THE COAST OVERNIGHT THURSDAY NIGHT...WITH SLIGHT CHANCE POPS FOR THE COASTAL PLAINS FRIDAY. INCREASED POPS TO LOW END CHANCE BY SATURDAY. WILL BE WATCHING FOR THE POTENTIAL FOR THIS SYSTEM TO BECOME A BIT BETTER ORGANIZED WITH RESPECT TO A TROPICAL NATURE...ECMWF SHOWS THE UPPER LEVEL SHEAR WEAKENING BY THE TIME IT MOVES INTO THE WESTERN GULF OF MEXICO. TIME WILL TELL. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 86 77 88 72 90 / 70 30 30 10 10 VICTORIA 87 74 90 68 90 / 50 20 20 10 10 LAREDO 91 76 92 74 97 / 40 40 40 20 10 ALICE 88 75 90 70 92 / 40 30 40 10 10 ROCKPORT 86 79 88 74 89 / 70 30 30 10 10 COTULLA 89 74 90 71 94 / 40 50 40 20 10 KINGSVILLE 87 76 89 71 91 / 60 30 40 10 10 NAVY CORPUS 86 80 87 76 88 / 70 30 30 10 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ JV/71...SHORT TERM MG/88...LONG TERM tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 1102 AM CDT SUN SEP 30 2007 .UPDATE... THREAT FOR SEVERE THUNDERSTORMS WILL INCREASE THROUGH THE AFTERNOON INTO THE EARLY EVENING HOURS AS POTENT MID-LEVEL WAVE CURRENTLY OVER SWRN NEB MOVES EAST THROUGH IOWA. STRONG CONVECTION HAS DEVELOPED DOWNSTREAM OF THIS WAVE WHERE STRONG LOW LEVEL MOIST/WARM ADVECTION ON POTENT 50-60KT 850MB WIND MAXIMUM ON KS/NEB PROFILERS CONTINUES. THIS CONVECTION SHOWING HINTS OF PRODUCING SMALL HAIL OVER NRN IA/SRN MN PER KARX/KDMX RADAR IMAGERY. THIS SHOULD CONTINUE TO DEVELOP...LARGELY IN ENVIRONMENT LACKING DEEP INSTABILITY /MUCAPE LESS THAN 500 J/KG/ BUT INCREASING THERMODYNAMIC/KINEMATIC FORCING AS WAVE CONTINUES TO APPROACH. DON/T EXPECT ANYTHING SEVERE FOR THE MOST PART WITH THIS INITIAL ACTIVITY OWING TO OVERALL LACK OF INSTABILITY AND GRADUAL WEAKENING OF LOW LEVEL JET VIA MIXING. MAY BE A ROGUE DIME TO NICKEL SIZED HAIL REPORT WITH THE STRONGEST CORES...HOWEVER. LATEST 30.12 RUC/WRF...AS WELL AS SPC/NSSL WRF RUNS...ALL AGREE THAT MORE ROBUST DEVELOPMENT WILL OCCUR BEHIND/SOUTH OF THIS INITIAL ACTIVITY OVER WRN/CNTL IA IN THE MID TO LATE AFTN HOURS AS STRONG MID/UPPER LEVEL KINEMATICS AND ATTENDANT SURFACE LOW AND COLD FRONT MOVE NORTHEAST INTO THE MAIN INSTABILITY AXIS...WHICH WILL FEATURE MLCAPES FROM 500 TO 1500 J/KG /MORE OVER IOWA/. NARROW WINDOW /ESPECIALLY IN NAM-WRF/ EXISTS IN 20Z-02Z TIMEFRAME FOR THE STRONGEST WINDS IN THE CYCLONICALLY CURVED MID/UPPER JET TO OVERSPREAD THE FRONTAL ZONE SUPPORTING SUPERCELLULAR SHEAR IN PEAK HEATING. THUS...EXPECT LINEAR STORM MODE /COLD FRONT/ TO FEATURE SOME HIGHER END ORGANIZATION ESPECIALLY NEAR/NORTHEAST OF SFC LOW WHICH WILL MOVE ACRS IOWA. RUC A TAD MORE SOUTH...SUGGESTING HIGHER THREAT FOR TORNADIC POTENTIAL STAYS SOUTH OF FORECAST AREA...BUT REGARDLESS...STORMS THIS AFTERNOON/EVENING WILL NEED TO BE WATCHED CLOSELY. SREF SEVERE STORM PROBABILITIES HAVE BEEN VERY CONSISTENT IN SUGGESTING BIGGEST FLARE-UP OF SEVERE WEATHER WILL TAKE PLACE IN I-35 CORRIDOR IN MID/LATE AFTN...AND DECREASE MARKEDLY AS CINH INCREASES THROUGH THE EARLY EVENING. FORECAST IN GREAT SHAPE. ADDED SEVERE WORDING IN NERN IA WHERE BUST JUXTAPOSITION OF SHEAR/INSTABILITY IS PROGGED. WILL UPDATE HAZARDOUS WEATHER OUTLOOK WITH LATEST THOUGHTS BETWEEN 18-20Z. BINAU && .PREV DISCUSSION... /ISSUED 320 AM CDT SUN SEP 30 2007/ SHORT TERM...THROUGH TUESDAY NIGHT PRIMARY FORECAST CHALLENGES WERE ASSOCIATED WITH A COUPLE OF ANOMALOUSLY VIGOROUS SYSTEMS TO IMPACT THE FORECAST AREA IN THE SHORT TERM. DETAILS OF CONCERN WERE WITH RAIN CHANCES TODAY AND TONIGHT...ALONG WITH SEVERE WEATHER POTENTIAL THIS AFTERNOON/EVENING. RAIN CHANCES TUESDAY INTO TUESDAY NIGHT WERE ALSO A CONCERN. STRONG SOUTHERLY FLOW ONGOING EARLY THIS MORNING ACROSS THE UPPER MISSISSIPPI VALLEY AHEAD OF SURFACE COLD FRONT ADVANCING ACROSS THE PLAINS. LOW LEVEL WARM AIR ADVECTION AND MOISTURE TRANSPORT EVIDENT ON 40-50KT 850MB JET...WHICH WAS FOCUSED FROM NEBRASKA/KANSAS INTO NORTHWEST IOWA AND MN. CLUSTERS OF CONVECTION AHEAD OF PLAINS COLD FRONT PRODUCING CONSIDERABLE HIGH CLOUDINESS ACROSS THE FORECAST AREA. WATER VAPOR IMAGERY SHOWED VIGOROUS MID LEVEL CIRCULATION TRACKING OUT INTO THE HIGH PLAINS OF WYOMING/COLORADO. 00Z 30SEP07 MODELS HAD EXCELLENT CLUSTERING OF UPPER LEVEL AND SURFACE FEATURES TO IMPACT THE UPPER MISSISSIPPI VALLEY TODAY AND TONIGHT...AS WELL AS TUESDAY INTO TUESDAY NIGHT. AS WAS THE CASE IN PREVIOUS PROBABILISTIC DATA SUITE...LATEST SREF INDICATED 80-100 PERCENT PROBABILITIES OF QPF TODAY INTO TONIGHT. SIMILAR VALUES WERE ASSOCIATED WITH SYSTEM FOR TUESDAY INTO TUESDAY NIGHT. AS A RESULT...FORECAST CONFIDENCE REMAINS HIGH FOR A WIDESPREAD RAIN EVENT ACROSS THE FORECAST AREA IN BOTH OF THE AFOREMENTIONED TIME FRAMES. TODAY INTO TONIGHT...FIRST OF TWO RATHER VIGOROUS SYSTEMS IMPACTS THE AREA. EXCELLENT CONSENSUS WITHIN DETERMINISTIC AND PROBABILISTIC DATA SUITE SUPPORTS HIGH FORECAST CONFIDENCE IN DETAILS OF CURRENT DATA BASE. STRONG DYNAMICS MANIFESTED BY 500-300MB PV-ADVECTION...ALONG WITH DEEP LAYERED Q-G CONVERGENCE. RAIN PROBABILITIES IN CURRENT DATA BASE SUPPORTED WELL BY FORCING PARAMETERS...WITH CATEGORICAL VALUES GENERALLY ALONG AND WEST OF THE MISSISSIPPI RIVER THIS AFTERNOON. IN ADDITION...UPPER LEVEL DIVERGENCE ASSOCIATED WITH 300MB JET SHOULD AID IN ENHANCEMENT OF LARGE SCALE ASCENT AND THUS DEFORMATION AXIS LINGERS THROUGH THE NIGHT ACROSS NORTHERN SECTIONS OF THE FORECAST AREA. THEREFORE...INCREASED RAIN PROBABILITIES THIS EVENING AREAWIDE...THEN IN THE AFOREMENTIONED LOCATIONS BASED ON CONSISTENT SIGNAL OF DEFORMATION ZONE ACROSS NORTHERN WI. BOTH GFS AND NAM/WRF CONTINUED TO INDICATE A NARROW RIBBON OF INSTABILITY WITH SBCAPE VALUES OF AS MUCH AS 500-1000 J/KG ARCING INTO PORTIONS OF THE FORECAST AREA THIS AFTERNOON AND EVENING. THIS COMBINED WITH 0-6KM SHEAR OF 40-50KTS SHOULD FAVOR A FAST MOVING LINE OF STRONG CONVECTION PIVOTING NORTHEASTWARD. DUE TO STRONG WIND SHEAR...ENVIRONMENT FAVORS LOW-TOPPED SUPERCELLS WITH ANY DISCRETE CELLS. PLEASE REFERENCE 06Z 30SEP07 SPC DAY ONE OUTLOOK... ALONG WITH LOCAL HAZARDOUS WEATHER OUTLOOK FOR FURTHER INFORMATION. TUESDAY INTO TUESDAY NIGHT...FORECAST CONFIDENCE REMAINS HIGH FOR YET ANOTHER WIDESPREAD RAIN EVENT ACROSS THE FORECAST AREA. STRONG FORCING SIGNALS SUPPORTED THIS AS EVIDENCED BY DEEP LAYERED Q-G CONVERGENCE...AS WELL AS LOW LEVEL MOISTURE TRANSPORT AND THETA-E CONVERGENCE ALONG/AHEAD OF THE COLD FRONT. RAIN PROBABILITIES WERE INCREASED ACROSS THE FORECAST AREA BY DAY SHIFT AND THIS LOOKED GOOD. FURTHER INCREASE WILL PROBABLY BE WARRANTED WITH SUBSEQUENT FORECASTS BASED ON GOOD MODEL CONSENSUS AND STRONG FORCING SIGNALS. LONG TERM...WEDNESDAY THROUGH SATURDAY AFTER THE ACTIVE WEATHER OF LATE SETTLES DOWN AT MIDWEEK... DETERMINISTIC GFS AND ECMWF INDICATED AN UPPER LEVEL AND SURFACE WAVE SHOULD IMPACT THE UPPER MISSISSIPPI VALLEY TOWARD THE END OF THE WEEK. FORECAST CONFIDENCE WAS GROWING...AS BOTH MODELS WERE GAINING GOOD CONSENSUS ON TIMING AND STRENGTH OF UPPER LEVEL WAVE AND ASSOCIATED SURFACE FRONT. AT THIS TIME...CURRENT DATA BASE APPEARS REASONABLE WITH RAIN CHANCES FRIDAY INTO SATURDAY. NO CHANGES WERE MADE TO THE EXTENDED OUTLOOK. AVIATION... AN AREA OF RAIN AND SCATTERED THUNDERSTORMS HAS DEVELOPED ON THE NOSE OF A 45 KNOT 850 MB JET ACROSS NORTH CENTRAL IOWA AND SOUTH CENTRAL MINNESOTA EARLY THIS MORNING. NONE OF THE SEPTEMBER 30TH 00Z MODELS PICKED UP ON THIS CONVECTIVE SYSTEM. CORFIDI VECTORS SUGGESTS THAT THIS SYSTEM SHOULD MOVE NORTHEAST ACROSS PARTS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA EARLY THIS MORNING. AS A RESULT...I JUST RECENTLY ADDED SHOWERS TO THE KRST TAF. A VIGOROUS NEGATIVELY SHORT WAVE TROUGH WILL MOVE THROUGH THE UPPER MISSISSIPPI RIVER VALLEY LATE THIS AFTERNOON AND TONIGHT. THIS WILL RESULT IN WIDESPREAD SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND SHOWERS AND ISOLATED THUNDERSTORMS TONIGHT. IN ADDITION...THERE MAY BE SOME SEVERE WEATHER CONVECTION BETWEEN SEPTEMBER 30TH 21Z AND OCTOBER 1ST 03Z. THE MAIN SEVERE WEATHER THREATS LOOK TO BE DAMAGING WINDS AND LARGE HAIL. HOWEVER THERE MAY BE A FEW TORNADOES ACROSS SOUTH CENTRAL AND SOUTHEAST MINNESOTA AND NORTHEAST IOWA WHERE THE WINDS ARE ABLE TO BACK AHEAD OF THE STRENGTHENING SURFACE LOW. ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. $$ SHORT/LONG TERM...THOMPSON && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 320 AM CDT TUE OCT 2 2007 .DISCUSSION... THE MAIN FORECAST ISSUE IN THE NEAR TERM IS THE PASSAGE OF ANOTHER STRONGLY FORCED FRONTAL SYSTEM TODAY. STRONG WAA AND MOISTURE TRANSPORT IS UNDERWAY EARLY THIS MORNING ACROSS EASTERN NEBRASKA AND WESTERN IOWA. CURRENT LAPS SOUNDINGS ACROSS SW IA INDICATE PLENTY OF DRY AIR TO OVERCOME BELOW ABOUT 15K FEET...BUT THE NAM/GFS/RUC ALL QUICKLY SATURATE AND GENERATE PRECIP ACROSS WESTERN SECTIONS AFTER 12Z. ELEVATED INSTABILITY COULD SUPPORT A LIMITED HAIL THREAT THIS MORNING. OTHERWISE...THE FAR SOUTHEAST REMAINS OUTLOOKED IN SLIGHT RISK. SEVERE POTENTIAL WILL AGAIN BE DEPENDENT ON AMOUNT OF AFTERNOON INSOLATION. THE NAM MAY BE OVERDONE AT 1500-2000 J/KG CAPE...BUT GIVEN ENOUGH AFTERNOON HEATING...LOW LEVEL SHEAR AND LOW LCL`S WOULD SUPPORT A TORNADO THREAT IN ADDITION TO STRAIGHT LINE WINDS. CONVECTION WILL QUICKLY HEAD EAST OF THE FORECAST AREA AFTER 00Z THIS EVENING. ZONAL UPPER FLOW WILL THEN GRADUALLY RETURN TO SOUTHWESTERLY LATE WEDNESDAY INTO THURSDAY WHEN AFTERNOON TEMPERATURES WILL REBOUND INTO THE UPPER 70S TO LOWER 80S. WILL CONTINUE TO CARRY CHC POPS...ESPECIALLY NORTH HALF THURSDAY NIGHT AS A WARM FRONT LIFTS THROUGH THE STATE. THE MOST FAVORABLE MOISTURE CONVERGENCE AND INSTABILITY SHOULD STAY JUST TO THE NORTHWEST OF IOWA...WHERE THE NEW DAY 3 SLIGHT RISK IS OUTLOOKED. AS WE LOOK AHEAD TO THE WEEKEND...THE GFS CONTINUES TO HAVE MAJOR CONSISTENCY ISSUES. THE 01/12Z RUN HAD THE H5 LOW ACROSS THE OHIO VALLEY BY 12Z TUESDAY...AND THE 02/00Z RUN NOW HAS IT IN ONTARIO AT THE SAME TIME. THE ECMWF BRINGS A COLD FRONT INTO WESTERN IOWA BY SATURDAY EVENING...AND THEN MAINTAINS A CUTOFF LOW NEAR IOWA ALL THE WAY INTO NEXT TUESDAY. WITH SUCH A MUDDLED PICTURE IN THE MEDIUM RANGE...NO SENSE IN MAKING ANY MAJOR CHANGES RIGHT NOW AND WILL KEEP POPS GOING FOR SATURDAY INTO SUNDAY. DAY SHIFT CAN RE-EVALUATE AND ADJUST WHERE NECESSARY. && .AVIATION...02/06Z LIGHT RADAR RETURNS ACROSS NEBRASKA INDICATE MID-LEVEL SATURATION IS PROGRESSING AND THIS WILL CONTINUE THROUGH THE EARLY MORNING HOURS WITH STRONG SW FLOW AND APPROACHING SHORT WAVE TROUGH. WILL MENTION A 6 HR WINDOW OF CONVECTION FROM WEST TO EAST TODAY...BEGINNING AT 15Z AT KFOD...AND STAGGERED TO 18Z AT KOTM. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ LONG TERM...KINNEY SHORT TERM...DONAVON AVIATION...SMALL ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 431 AM EDT TUE OCT 2 2007 .SYNOPSIS... 07Z WATER VAPOR IMAGERY AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING COVERING MUCH OF THE EAST HALF OF THE U.S....EXCLUDING AN UPPER LOW OVER LAKE ERIE...AND A TROUGH STRETCHING FROM CENTRAL MONTANA INTO NORTHERN UTAH. QUIET WEATHER CURRENTLY EXISTS ACROSS THE CWA WITH THE AREA BETWEEN THE UPPER LOW AND TROUGH...WITH THE ONLY ISSUES BEING IN THE AVIATION DEPARTMENT WITH LOW CLOUDS AND VISIBILITIES STUCK UNDERNEATH A RADIATIONAL AND COLD FRONTAL INVERSION (SEE 00Z APX SOUNDING). SO FAR...THE ONLY PLACES AROUND DENSE FOG ADVISORY CRITERIA ARE ESC...MNM...ISQ AND ERY PER OBS. THESE LOW CLOUDS EXTEND INTO EASTERN MN...AND HAVE HELPED TO KEEP TEMPERATURES AND DEWPOINTS UP INTO THE MID TO UPPER 50S. TO THE WEST...LOW PRESSURE HAS DEVELOPED NEAR PIERRE SOUTH DAKOTA DUE TO DOWNSLOPING FLOW OFF THE ROCKIES AND HEIGHT FALLS AHEAD OF THE INTERMOUNTAIN WEST TROUGH. VERY LITTLE IN THE WAY OF PCPN IS OCCURRING ALONG THE LOWS ASSOCIATED COLD FRONT...WITH MOSTLY HIGH CLOUDS PRESENT. THIS IS DUE TO A LOT OF LOW AND MID LEVEL DRY AIR AS SEEN ON THE 00Z NORTH PLATTE NEBRASKA SOUNDING. ANY PCPN AT THE MOMENT WITH THE ENTIRE TROUGH IS FARTHER WEST OVER UTAH AND COLORADO. ALTHOUGH THE PCPN IS FAIRLY MINIMAL...THE SYSTEM IS PRODUCING PLENTY OF WIND...WITH PROFILERS ACROSS NEBRASKA AND WESTERN KANSAS IN THE 40-50KT RANGE AT 850MB. THESE WINDS...MOSTLY FROM THE SSW...ARE TRANSPORTING 850MB DEWPOINTS OF AROUND 10C NORTHWARD FROM WEST TEXAS AND SW KANSAS PER 00Z RAOBS. && .DISCUSSION... TODAY AND TONIGHT...MODELS (GFS/NAM/UKMET/CANADIAN) ARE ALL IN GOOD AGREEMENT WITH REGARDS TO THE PROGRESSION AND TIMING OF THE UPPER LEVEL TROUGH AND COLD FRONT MOVING EASTWARD. THEY ALL HAVE TRENDED TOWARDS THE SLOWER IDEA PRESENTED BY THE 00Z NAM/UKMET SHOWN YESTERDAY. BY 00Z WED...THE TROUGH IS PROGGED TO BE OVER CENTRAL MINNESOTA WITH THE COLD FRONT IN WESTERN WI. BY 12Z WED...BOTH THE TROUGH AND FRONT ARE PROGGED TO BE LOCATED OVER EASTERN ONTARIO AND LOWER MICHIGAN...WITH STRONG DRYING COMING IN BEHIND IT. UNTIL THAT OCCURS...THE AREA WILL BE UNDER A WARM ADVECTION PATTERN AHEAD OF THE TROUGH...WHICH SHOULD BRING UP A NARROW ZONE OF 850MB THETA-E ADVECTION INTO THE CWA. WITHIN THIS ZONE...SHOWERS AND SOME THUNDERSTORMS ARE EXPECTED TO DEVELOP AS HEIGHT FALLS COME ACROSS FROM THE UPPER TROUGH. IT APPEARS THIS DEVELOPMENT WILL TAKE PLACE EARLY THIS AFTERNOON OVER MN/WI AND PERHAPS THE FAR WESTERN U.P....THEN GRADUALLY MOVE EASTWARD THROUGH THE AFTERNOON AND NIGHT. BEST CHANCES FOR RAIN APPEARS TO BE TONIGHT...THOUGH...GIVEN THE SLOWER MOTION PROGGED WITH THE TROUGH/COLD FRONT. TEMPERATURES WILL HAVE A HARD TIME WARMING WITH ALL THE CLOUD COVER...BUT SOUTHERLY WINDS SHOULD BE ABLE TO GIVE AT LEAST A 5-10 DEGREE RISE. BUMPED UP LOWS TONIGHT...PARTICULARLY IN THE EAST DUE TO THE SLOWER MOTION OF THE FRONT. WED THROUGH THU...DRY AIR ADVECTION THAT OCCURRED BEHIND TONIGHTS UPPER TROUGH SHOULD SET THE STAGE FOR QUIET WEATHER DURING THIS PERIOD. AN UPPER TROUGH CURRENTLY OVER THE EAST PACIFIC IS PROGGED TO DIG DOWN INTO THE WEST COAST...CAUSING HEIGHT RISES DOWNSTREAM. THESE HEIGHT RISES WILL PROMPT WARM ADVECTION OVER THE AREA...HOWEVER GIVEN THE DRY AIRMASS PRESENT...VERY LITTLE CLOUD COVER IS EXPECTED. ONLY ACROSS ISLE ROYALE AND WESTERN LAKE SUPERIOR WED NIGHT AND THU IS THERE EXPECTED TO BE PARTLY TO MOSTLY CLOUDY SKIES...WHERE THE BEST MOISTURE CONVERGENCE IS PROGGED. THE WARM ADVECTION WILL ALLOW 850MB TEMPS TO CLIMB TO 8C AT 18Z WED AND TO 14C BY 18Z THU. WE SHOULD BE ABLE TO MIX UP TO 850MB ON WED...GIVEN THE COOLER CONDITIONS...AND THUS ALLOW HIGHS TO REACH THE UPPER 60S TO LOW 70S. ON THU...GIVEN THE SUN ANGLE...IT MAY BE HARD TO REACH 850MB...AND THUS HAVE ONLY WENT WITH HIGHS IN THE LOW TO MID 70S. THU NIGHT AND FRI...WARM AND MOIST AIR ADVECTION IS PROGGED TO INCREASE ACROSS THE PLAINS...UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES AS THE TROUGH OVER THE WEST COAST CONTINUES TO DIG TOWARDS THE FOUR CORNERS. LEFT IN SLIGHT CHANCE POPS FOR AFTER 06Z THU NIGHT FOR THE FAR WESTERN U.P. AND WESTERN LAKE SUPERIOR WHERE ENOUGH MOISTENING OF THE LOW AND MID LEVELS TAKE PLACE. CONDITIONS LOOK BETTER FOR PCPN DEVELOPING ON FRI WITH CONTINUED MOISTENING AND THE PROSPECTS OF A SHRTWV OR SHRTWVS CROSSING...AS INDICATED BY THE 00Z ECMWF/GFS. TO GIVE AN IDEA OF THE MOISTENING...850MB DEWPOINTS AT IMT CLIMB FROM -4C AT 00Z FRI TO 12C AT 00Z SAT. HAVE INCREASED POPS TO 40 FOR FRI. FRI NIGHT THROUGH SUN...THIS PERIOD OF THE FORECAST CAN HAVE A LOT OF BUST POTENTIAL...WITH UNCERTAINTIES ABOUT HOW THE WESTERN TROUGH EVOLVES. IT DOES SEEM LIKE...THOUGH...THAT MODELS ARE FOCUSING ONTO MORE RIDGING ACROSS UPPER MICHIGAN WITH THE ONLY EXCEPTION BEING THE 00Z UKMET WHICH IS VERY PROGRESSIVE WITH THE WESTERN TROUGH. THE SCENARIO OF MORE RIDGING...WITH A POSSIBLE FRONTAL BOUNDARY OVER THE AREA SEEMS MORE LIKELY. TO THE SOUTH OF THIS BOUNDARY...WARM AND HUMID CONDITIONS FOR OCTOBER ARE EXPECTED. NORTH OF THE BOUNDARY...COOLER WEATHER WITH SHOWERS AND THUNDERSTORMS SEEM LIKELY WITH 850MB DEWPOINTS AROUND 14C. EITHER WAY...IT WAS NECESSARY TO RAISE TEMPERATURES UP THROUGH THE PERIOD...WITH A SIGNIFICANT INCREASE ON FRI NIGHT WITH A WARM FRONTAL BOUNDARY PROGGED TO BE JUST NORTH OF UPPER MICHIGAN. MORE ADJUSTMENTS TO THE EXTENDED WILL BE NEEDED. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... THE STRATUS DECK OVER THE AREA HAS HELPED TO LIMIT FOG FORMATION THIS EVENING. NEVERTHELESS...CANNOT RULE OUT LOWER STRATUS OR FOG FORMATION LATER TONIGHT WITH VSBY FALLING AOB 1SM GIVEN ABUNDANT MOISTURE EVIDENT ON 00Z KSAW TAMDAR SOUNDING IN THE SFC-900 MB LAYER. STRENGTHENING SRLY FLOW AND DEEPER MIXING TUE AHEAD OF THE NEXT TROUGH SHOULD HELP LIFT CIGS TO VFR IN THE AFTERNOON. THE BULK OF THE PCPN WITH THE NEXT SHORTWAVE TROUGH IS EXPECTED TO HOLD OFF UNTIL UNTIL AROUND 22Z AT KCMX AND 01Z AT KSAW. PCPN WITH SHOWERS AND POSSIBLY AND A FEW ISOLATED THUNDERSTORMS WILL HELP LOWER CIGS/VSBYS BACK INTO THE MVFR RANGE. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FCST ISSUANCE)... NEXT ACTIVE LOW PRES TROUGH WILL RACE E FROM THE PLAINS TODAY AND CROSS LAKE SUPERIOR TONIGHT. SRLY WINDS WILL RAMP UP IN ADVANCE OF THIS TROUGH TO GENERALLY 15 TO 25KT...BUT IT`S NOT OUT OF THE QUESTION THAT A FEW GALE FORCE GUSTS TO 35 KT COULD OCCUR OVER THE E HALF OF THE LAKE LATE THIS AFTN/EVENING. W GALE FORCE GUSTS TO 35 KT COULD OCCUR IMMEDIATELY AFTER TROF PASSAGE FROM AROUND THE KEWEENAW PENINSULA EWD LATE TONIGHT/EARLY WED MORNING. WINDS FOR THE REMAINDER OF THE FCST (WED AFTN THRU SAT) SHOULD GENERALLY BE IN THE 10 TO 20KT RANGE WITH AN OCCASIONAL PERIOD OF 15 TO 25KT. && .MQT WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 11 AM EDT TUESDAY MIZ004>007-010>014-084-085. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...JLB MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 220 AM EDT TUE OCT 2 2007 .SYNOPSIS... STRONG SURFACE RIDGING EXTENDING FROM THE NEW ENGLAND COAST SOUTHWEST TO THE SOUTHERN APPALACHIANS IS EXPECTED TO GRADUALLY WEAKEN THROUGH THURSDAY. A COASTAL TROUGH IS FORECAST TO DEVELOP TODAY INTO WEDNESDAY... WHICH SHOULD GRADUALLY MOVE INLAND OVER EASTERN NORTH CAROLINA THURSDAY. MOISTURE AND THE CHANCE OF RAIN WILL INCREASE OVER CENTRAL NORTH CAROLINA ESPECIALLY WEDNESDAY AND THURSDAY. && .NEAR TERM /THROUGH TODAY/... THE 200 AM DATA ANALYSIS INDICATED STRONG SURFACE HIGH PRESSURE (1030+ MB) OVER NEW ENGLAND... EXTENDING SW DOWN THE APPALACHIANS). THERE WAS A DEVELOPING SURFACE TROUGH WELL OFFSHORE OF THE SOUTHEAST U.S. COAST. THE 00Z RAOBS INDICATED A DEEPENING EASTERLY FLOW FROM OFF THE ATLANTIC OVERSPREADING THE REGION ESPECIALLY FROM THE BOUNDARY LAYER THROUGH H8. THERE WERE ONLY A FEW CIRRUS OVERHEAD OF CENTRAL NC AS OF 200 AM. WE CONTINUE TO ANTICIPATE A LOW STRATUS LAYER TO DEVELOP NEAR THE COAST AND SPREAD INLAND OVER THE COASTAL PLAIN AND SANDHILLS BETWEEN 06Z-12Z THIS MORNING. THE STRATUS SHOULD SPREAD WESTWARD INTO THE PIEDMONT BEFORE OR AROUND SUNRISE. THE LATEST SATELLITE DATA INDICATED STRATUS DEVELOPING RAPIDLY OVER THE COASTAL AREA... AND WERE SPREADING INLAND. THE CURRENT FORECAST OF BECOMING CLOUDY THIS MORNING SHOULD BE REALIZED BEFORE DAYBREAK IN ALL BUT THE FAR NW. TEMPS WILL BE WARMER THIS MORNING... AS DEW POINTS AND CLOUDS INCREASE. EXPECT MOSTLY MID 50S TO LOWER 60S. THE REST OF TODAY SHOULD BE DOMINATED BY THE MORNING STRATUS WHICH SHOULD BE SLOW TO BECOME BROKEN TO SCATTERED STRATOCUMULUS BY EARLY TO MID AFTERNOON. THE PRESSURE GRADIENT BETWEEN THE RIDGING OVER THE WESTERN SECTIONS AND THE DEVELOPING COASTAL TROUGH WILL BRING AN INCREASE IN THE NE SURFACE WINDS... ESPECIALLY OVER THE COASTAL PLAIN THIS AFTERNOON (10-20 MPH)... WITH LESS BREEZE OVER THE PIEDMONT. LOW LEVEL THICKNESSES SUPPORT WARMER HIGHS TODAY INTO THE MID 80S... YET THE CLOUDS AND INCREASED MOISTURE SHOULD TEMPER THE WARMTH. EXPECT HIGHS MOSTLY 78-83. WITH NO SUPPORT FOR SHOWERS... WE WILL KEEP POP NIL TODAY. && .SHORT TERM /TONIGHT THROUGH THURSDAY/... IT APPEARS THAT THE MODELS ARE FINALLY COMING INTO SOME AGREEMENT IN THE DEPICTION OF INCREASING MOISTURE OVER CENTRAL NC OVER THE NEXT FEW DAYS... HIGHLIGHTED BY INCREASING POP FOR WEDNESDAY INTO THURSDAY. THE LATEST GFS RUNS HAVE GONE MUCH WETTER THAN IN PREVIOUS DAYS... AND WERE MORE IN LINE WITH THE WETTER NAM... WRF... AND ECMWF. HOWEVER... THE 00Z/02 OCTOBER NAM CONTINUED TO BE STRONGER THAN THE OTHER MODELS WITH THE MID LEVEL SYSTEM EXPECTED TO DEVELOP NEAR THE COAST WEDNESDAY INTO THURSDAY. THE 12Z ECMWF AND 00Z UKMET ARE MORE IN LINE WITH THE GFS IN DEPICTING A WEAKER SYSTEM THAN THE NAM NEAR THE COAST BY MID WEEK... WHICH ACTUALLY ALLOWS MORE MOISTURE TO GET TRANSPORTED WESTWARD INTO CENTRAL NC. IF A STRONGER COASTAL SYSTEM DEVELOPS... MOST OF THE MOISTURE WILL LIKELY BE FOCUSED VERY NEAR THE COAST. THE BOTTOM LINE FOR CENTRAL NC... THE 00Z/02 OCTOBER GFS IS THE FAVORED MODEL... WITH SUPPORT FROM MOST OF THE LATEST MODEL SOLUTIONS... IN DEPICTING A COASTAL TROUGH DEVELOPMENT TODAY INTO WEDNESDAY. THIS TROUGH SHOULD BE PULLED INLAND OVER THE COASTAL PLAIN WEDNESDAY NIGHT AND THURSDAY. THE STRONG RIDGING OVER THE APPALACHIANS IS EXPECTED TO GRADUALLY WEAKEN. MOISTURE IS EXPECTED TO CONTINUE TO INCREASE FROM THE E-SE (FIRST IN THE LOW LEVELS TODAY... THEN THROUGHOUT THE COLUMN WEDNESDAY INTO THURSDAY). PW`S ARE FORECAST TO EXCEED 2 INCHES WEDNESDAY INTO THURSDAY. SHOWERS ARE EXPECTED TO BE AIDED BY LOW LEVEL CONVERGENCE (COASTAL TROUGH)... ISENTROPIC LIFT (MOISTURE FLOW OFF THE ATLANTIC RIDING A TOP THE SHALLOW MORE STABLE NEAR SURFACE LAYER).... AND AFTERNOON HEATING (INSTABILITY). ALTHOUGH THERE COULD BE SOME SPOTTY DRIZZLE WEDNESDAY MORNING... THE BEST CHANCE OF SHOWERS WILL COME WEDNESDAY AND THURSDAY (BOTH AFTERNOON AND EVENING PERIODS) AS THE COASTAL TROUGH ADVANCES INTO THE COASTAL PLAIN. THE UPSLOPE FLOW AND ISENTROPIC LIFT ALSO FAVOR AT LEAST SOME RAINFALL ALL THE WAY INTO THE BLUE RIDGE. THEREFORE... WE WILL CONTINUE TO ADVERTISE THE HIGHEST POP EAST BUT INCREASE THE POP ALL LOCATIONS WED AND THURS. WE WILL CONTINUE TO BE CONSERVATIVE WITH THE POP (GO WITH HIGH CHANCE - 40 AND 50)... AND QPF (KEEP UNDER 0.25) UNTIL WE GET ANOTHER COUPLE OF AGREEABLE MODEL RUNS. DAILY HIGHS WED AND THUR SHOULD BE HELD DOWN BY THE INCREASED CLOUDS AND SHOWER CHANCES. WE WILL UNDERCUT THE MAV MOS BY A FEW DEGREES (HIGHS MOSTLY 75-80). LOWS WILL BE WELL ABOVE NORMAL WITH THE INFLUX OF MOISTURE (65-70). && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... LONG TERM PERIOD IS CHARACTERIZED BY HIGH UNCERTAINTY DUE TO THE POOR RUN TO RUN CONTINUITY AND THE LACK OF A MODEL CONSENSUS AMONG THE MEDIUM RANGE MODELS REGARDING THE GULF OF MEXICO LOW AND THE ASSOCIATED INVERTED COASTAL TROUGH. THE LATEST ECMWF WHICH MOVES THE GULF OF MEXICO SYSTEM DUE WEST IS THE OUTLIER...AS IT HISTORICALLY PERFORMS POORLY WITH WEAK TROPICAL/SUBTROPICAL SYSTEMS. THE 12Z/01 NAM AND GFS ARE COMING MORE IN LINE WITH THE CANADIAN....LIFTING A MORE SHEARED SYSTEM NORTH INTO THE GULF COAST STATES. WILL KEEP A LOW CHANCE POPS THURSDAY NIGHT AS BOTH THE NAM AND GFS INDICATE COASTAL TROUGH/850 WARM FRONT OVER THE AREA WITH PRECIPITABLE WATERS AT OR ABOVE 2.0 INCHES. AFTERWORDS...IT IS REALLY ANYBODY`S GUESS. THE LATEST 00Z GFS WOULD DEFINITELY INDICATE A HIGHER PROBABILITY FOR RAIN AND COOLER TEMPERATURES DUE TO CLOUD COVER. FOR NOW WILL CONTINUE WITH ABOVE SEASONAL NORMALS WITH HIGHS IN THE LOWER TO MID 80S AND LOWS IN THE 60S. && .AVIATION /06Z TUESDAY THROUGH SATURDAY/... ANOTHER DAY OF NORTHEAST FLOW ON TAP WITH HIGH PRESSURE OVER NEW ENGLAND AND SFC RIDGING EXTENDING DOWN THE LEE OF THE MOUNTAINS. THERE WILL BE A STRONG POSSIBILITY OF IFR/LIFR CEILINGS IN LOW STRATUS AND/OR MVFR VISIBILITY IN FOG BETWEEN 08Z AND 14Z THIS MORNING. SOME VFR STRATUS AND STRATO CU DEVELOPED OVER EASTERN NC AND/OR ADVECTED INLAND OFF THE ATLANTIC YESTERDAY MORNING...WITH CEILINGS AROUND 5-6 KFT. LOOKING AT THE GFS/NAM BUFR AND RUC SOUNDINGS...AND ALSO LOOKING AT THE MAV/MET GUIDANCE...THERE ARE STRONG HINTS OF A LOW STRATUS LAYER DEVELOPING IN THE COASTAL PLAIN BEFORE SUNRISE...AND THE POSSIBILITY OF MVFR FOG ELSEWHERE. LATEST 11-3.9 SAT IMAGERY AND SFC OBSERVATIONS SHOW IFR/LIFR STRATUS ALREADY DEVELOPING AT ISO/PGV...WITH BKN CIGS AT 300-500 FT. TEMP/DEWPOINT SPREADS AS OF 06Z WERE ONLY 1-5F ALONG AND EAST OF HIGHWAY 1...WITH 5-10F SPREADS IN THE WEST/NW PIEDMONT. CURRENT THINKING IN THIS FLOW REGIME IS THAT FAY/RWI TAF SITES HAVE THE BEST CHANCE OF LOW STRATUS...FOLLOWED BY RDU AND THEN THE LOWEST CHANCE AT GSO/INT. DETERMINING WHEN ANY LOW STRATUS (FAY/RWI TAF SITES) WILL LIFT AND SCATTER OUT WILL BE THE PRIMARY FORECAST CHALLENGE. CURRENT THOUGHTS ARE THAT ANY LOW STRATUS WILL LIFT INTO A BROKEN VFR DECK BY 14-16Z. ELSEWHERE...SCT/BKN VFR DIURNAL CU AND STRATO CU IS EXPECTED DURING THE AFTERNOON HOURS. GFS/NAM BUFR SOUNDINGS SHOW 15-20 KT FLOW NOT TOO FAR OFF THE DECK AND THROUGHOUT THE MIXED LAYER AFTER 18Z THIS AFTERNOON IN THE COASTAL PLAIN...AND THIS IS THE BASIS FOR THE 14G20KT AT RWI/FAY TAF SITES FROM ROUGHLY 18-19Z UNTIL JUST BEFORE SUNSET. THIS MAY BE A LITTLE OVERDONE IF CLOUD COVER IS MORE PERVASIVE DURING THE AFTERNOON HOURS AND THE DEGREE OF DIURNAL HEATING/MIXING IS SOMEWHAT MITIGATED. THROUGH MID TO LATE WEEK...THE POSSIBILITY FOR IFR/LIFR STRATUS WILL INCREASE DURING THE POST-SUNSET AND PRE-DAWN HOURS WITH DEEP MOISTURE EXPECTED. MVFR/IFR CIGS AND VIS IN SHOWER ACTIVITY WILL ALSO BE POSSIBLE WED INTO THU. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BADGETT NEAR TERM...BADGETT/VINCENT SHORT TERM...BADGETT LONG TERM...BADGETT/RFG AVIATION...VINCENT nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1046 AM CDT TUE OCT 2 2007 .DISCUSSION... ISSUED 1035 AM CDT TUE OCT 2 2007 FORECAST APPEARS ON TRACK TODAY AND JUST MINOR UPDATES TO THE HOURLY GRIDS ACROSS CENTRAL/SE IL TODAY. A WARMER DAY THANKS TO BREEZY SOUTH WINDS. HIGHS IN THE LOWER TO MIDDLE 80S WITH INCREASING CLOUDS FROM THE WEST. SLIGHT CHANCE OF LATE DAY SHOWERS/THUNDERSTORMS OVER KNOX...FULTON AND SCHUYLER COUNTIES AFTER 4 PM. 15Z/10 AM SURFACE MAP SHOWS ELONGATED/DEEP 999 MB LOW PRESSURE ALONG THE MN/ND BORDER WITH ITS STRONG COLD FRONT EXTENDING SOUTH ACRSS FAR EASTERN SD INTO EASTERN NEBRASKA AND CENTRAL KS. 1032 MB HIGH PRESSURE WAS OFF THE NEW ENGLAND COAST AND RIDGING SW TOWARD TX. IL IN AN INCREASING SOUTHERLY FLOW BETWEEN THESE WX SYSTEMS. CIRRUS CLOUDS HAVE BEEN INCREASING/THICKENING FROM THE WEST EASTERN IL EAST OF I-57 STILL SEEING NEARLY SUNNY SKIES WITH PARTLY TO MOSTLY SUNNY SKIES FROM I-57 WEST. TEMPS WERE IN THE UPPER 60S TO MID 70S WITH DEWPOINTS IN THE UPPER 50S AND LOWER 60S. RUC AND NAM-WRF SIMILAR IN BRING THE COLD FRONT EAST INTO CENTRAL IA AND NW MO BY SUNSET/00Z WHILE QPF NUDGING INTO KNOX...FULTON AND SCHUYLER COUNTIES BETWEEN 4 AND 7 PM. HIGHS SHOULD REACH THE LOWER TO MIDDLE 80S AS CLOUDS INCREASE FROM THE WEST WITH BREEZY SOUTH WINDS GUSTING TO 15 TO 25 MPH. BRUNT OF SHOWERS AND THUNDERSTORMS MOVES INTO CENTRAL IL TONIGHT WITH COLD FRONT NEAR I-55 BY 06Z AND IN SE IL BY 12Z/WED. SPC HAS SLIGHT RISK OF SEVERE STORMS THIS EVENING WEST OF THE IL RIVER FOR MAINLY DAMAGING WIND GUSTS. HETTL && .AVIATION... ISSUED 652 AM CDT TUE OCT 2 2007...FOR THE 12Z TAFS PATCHY DENSE FOG HAS PLAGUED TAF SITES ALL NIGHT. VISIBILITY AND CIGS HAVE VARIED WIDELY BETWEEN VFR AND VLIFR. WILL TRY TO STAY AHEAD OF THE PREVAILING VIS FOR THE REST OF THIS FOG EVENT. DEC AND CMI HAVE BEEN THE ONLY SITES WITH MORE PERSISTENT VLIFR CONDITIONS THE LAST HOUR OR SO...SO WILL GO WITH PREVAILING VLIFR CONDITIONS...AND TEMPO IN MVFR OR VFR. AFTER 15Z...ALL SITES SHOULD JUST HAVE A BROKEN MID DECK DEVELOPING BY AFTERNOON. THE COLD FRONT IS EXPECTED TO ARRIVE THIS EVENING...WITH STRONG STORMS POSSIBLE BETWEEN 00Z AND 08Z. THE WINDOW FOR STORMS IN ANY LOCATION WILL MOST LIKELY BE VERY SIMILAR TO SUNDAY NIGHT...A 2 TO 4 HOUR TIME FRAME OF HEAVY RAINS AND STRONG WINDS. I LINGERED SOME MVFR CIGS AND SHOWERS FOR A FEW HOURS AFTER THE FRONT PASSES. SHIMON && .PREV DISCUSSION... ISSUED 330 AM CDT TUE OCT 2 2007 SHORT TERM...TODAY THROUGH THURSDAY. WATER VAPOR IMAGERY SHOWS STRONG SHORTWAVE TROUGH MOVING ACROSS WY/CO THIS MORNING... WITH AN EXPANSIVE PLUME OF MID/UPPER-LEVEL SUBTROPICAL MOISTURE STREAMING OUT AHEAD OF IT... STRETCHING FROM BAJA CALIFORNIA TO THE CENTRAL PLAINS. INTERESTING TO NOTE ALSO THAT THE REMNANTS OF TD JULIETTE WHICH IS CURRENTLY SHEARING OUT ACROSS THE NORTHERN SEA OF CORTEZ... ARE ALSO GETTING CAUGHT UP IN THIS MOIST CONVEYOR BELT. THIS EXTRA MID AND UPPER LEVEL MOISTURE IS PROGGED TO ADVECT INTO THE MISSISSIPPI VALLEY THIS AFTERNOON... RESULTING IN A RAPID INCREASE IN OVERALL MOISTURE... WITH PWAT VALUES NEARING THE 2-INCH MARK BY LATE AFTERNOON ACROSS EASTERN IA/WESTERN ILLINOIS. RESIDUAL LOW LEVEL MOISTURE IS STILL IN PLACE ACROSS THE REGION THIS MORNING... WITH LOW LEVEL DRY AIR NEVER REALLY MAKING IT IN BEHIND YESTERDAYS COLD FRONT. LOWER 70S DEWPOINTS LURK NOT TOO FAR TO THE SOUTH ACROSS OK/AR. NAM/GFS HAVE A GOOD HANDLE ON LOW LEVEL MOISTURE... AND SUGGEST A NARROW PLUME OF UPPER 60S DEWPOINTS ADVECTING INTO THE MISSISSIPPI VALLEY AHEAD OF THE COLD FRONT THIS AFTERNOON. CONVECTION SHOULD INITIATE EARLY THIS AFTERNOON ACROSS WESTERN IA/MO AHEAD OF A PREFRONTAL TROUGH CURRENTLY OVER EASTERN COLORADO. MAIN SHORTWAVE AND ATTENDANT COLD FRONT WILL QUICKLY CATCH UP TO THE INITIAL CONVECTION... AND THIS ADDED LARGE SCALE FORCING WILL LIKELY HELP THE CONVECTION TRANSITION TO MORE OF A LINEAR MODE. THE PROBLEM FOR US WILL BE THE POTENTIAL LACK OF INSTABILITY COUPLED WITH THE TIMING OF THE FROPA. WHILE THE MID/UPPER LEVEL MOISTURE PLUME WILL INCREASE PWAT VALUES ACROSS THE REGION... IT WILL ALSO RESULT IN WIDESPREAD MID/HIGH LEVEL CLOUD COVER ACROSS THE REGION... ALREADY SEEN IN SATELLITE IMAGERY ACROSS IOWA AND THE GREAT PLAINS. THIS MOISTURE WILL ALSO RESULT IN SHODDY MID- LEVEL LAPSE RATES... FURTHER DECREASING OVERALL CONVECTIVE INSTABILITY. HOWEVER... IT APPEARS STRONG SHEAR AND FORCING WILL MAKE UP FOR THIS LACK OF INSTABILITY... AT LEAST EARLY ON. CONTINUED TO KEEP POPS MAINLY CONTAINED TO AFTER 00Z... EXCEPT FOR A SLIGHT CHANCE IN THE EXTREME FAR WEST. OVERALL UPPER PATTERN SUGGESTS TWO PRIMARY AREAS FOR HEAVIER CONVECTION/QPF WILL BE FAVORED. ONE ACROSS EASTERN IOWA AND NORTHWESTERN ILLINOIS... WHICH WILL BE IN THE RRQ OF A 90-100KT JET STREAK AND CLOSER TO THE SHORTWAVE ENERGY AS IT LIFTS ACROSS WISCONSIN. THE SECOND AREA WILL LIKELY BE ACROSS THE LOWER MISSISSIPPI VALLEY WHERE OVERALL CONVECTIVE INSTABILITY WILL BE MUCH HIGHER. HIGHEST POPS ARE IN THE WEST FOR THIS EVENING... AS STRONG FORCING HELPS TO MAINTAIN STRONG CONVECTION AS IT CROSSES INTO WESTERN ILLINOIS. THIS UPPER LEVEL SUPPORT WILL QUICKLY OUTRACE THE THE CONVECTION BY MIDNIGHT... RESULTING IN A RAPID WEAKENING TREND AS THE STORMS LOSE THEIR SUPPORT AT LEAST THIS FAR SOUTH. THUS EXPECT OVERALL LOWER PRECIP COVERAGE AND QPF ACROSS EASTERN ILLINOIS. AREAS OF SOUTHEAST ILLINOIS MAY BENEFIT FROM SLIGHTLY HIGHER INSTABILITY AND COULD BE ON THE EASTERN EDGE OF THE AFOREMENTIONED SECOND FAVORED AREA FOR CONVECTION. SVR THREAT WILL MAINLY BE WIND... EXPECTING PRIMARILY LINEAR CONVECTION WITH BOWING SEGMENTS... BUT ISOLATED BOW ECHO TORNADOES ARE NOT OUT OF THE QUESTION... ESPECIALLY GIVEN SUCH IMPRESSIVE SHEAR PARAMETERS ACROSS EASTERN ILLINOIS BETWEEN 00 AND 03Z. 0-6KM SHEAR OF AROUND 50KTS... AND 0-1KM SHEAR OF 20-30KTS. COULD SEE SOME LINGERING SHOWERS ACROSS THE FAR EAST WEDNESDAY MORNING... BUT WILL ONLY HOLD ON TO A SLIGHT CHANCE FOR NOW... ESPECIALLY CONSIDERING HOW QUICKLY THE LAST SYSTEM DEPARTED. DRY CONDITIONS SHOULD LAST THROUGH WED AND THURSDAY UNDER ZONAL FLOW. LONG TERM...FRIDAY THROUGH MONDAY. ZONAL FLOW PATTERN WILL QUICKLY BECOME MORE AMPLIFIED BY THE END OF THE WORK WEEK... WITH A BROAD DIGGING TROUGH ACROSS THE WEST COAST AND BUILDING HEIGHTS ACROSS THE EASTERN CONUS. GFS HAS BEEN FLIP- FLOPPING OVER THE PAST 3 DAYS TRYING TO FIGURE OUT HOW QUICKLY TO CARRY THE WESTERN TROUGH WESTWARD. CONSIDERING THE LONG WAVELENGTH OF THE TROUGH AND THE RIDGING TO ITS EAST... WILL CONTINUE TO FAVOR THE SLOWER GUIDANCE... ESPECIALLY THE MORE CONSISTENT ECMWF AND CANADIAN GEM GLOBAL. WITH SOUTHWESTERLY FLOW IN PLACE... TEMPERATURES WILL REMAIN WELL ABOVE NORMAL... IN THE 80S. CANNOT OUTRULE SOME SCATTERED CONVECTION BECOMING AN ISSUE BY FRIDAY AND SATURDAY AFTERNOONS... ESPECIALLY IF ANY WEAK DISTURBANCES EJECT OUT OF THE MAIN TROUGH AND INTO THE PLAINS STATES... AS HAS BEEN SUGGESTED BY THE GFS/ECMWF/GEM OVER THE PAST FEW DAYS. THE GULF LOOKS TO BE WIDE OPEN DURING THIS PERIOD... WITH A SUSTAINED PERIOD OF RETURN MOISTURE FLOW. HOWEVER... PRECIP CHANCES ARE STILL TOO LOW TO BE MENTIONABLE AT THIS POINT... GIVEN THE UNCERTAINTIES WITH THE TIMING AND THE SUBTLE NATURE OF ANY POTENTIAL DISTURBANCES. ANY CONVECTION WOULD LIKELY FAVOR AREAS WEST OF THE MISSISSIPPI DURING THIS TIMEFRAME AS WELL... CLOSER TO THE LOW LEVEL JET. HARDIMAN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 740 AM EDT TUE OCT 2 2007 .SYNOPSIS (ISSUED AT 431 AM EDT)... 07Z WATER VAPOR IMAGERY AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING COVERING MUCH OF THE EAST HALF OF THE U.S....EXCLUDING AN UPPER LOW OVER LAKE ERIE...AND A TROUGH STRETCHING FROM CENTRAL MONTANA INTO NORTHERN UTAH. QUIET WEATHER CURRENTLY EXISTS ACROSS THE CWA WITH THE AREA BETWEEN THE UPPER LOW AND TROUGH...WITH THE ONLY ISSUES BEING IN THE AVIATION DEPARTMENT WITH LOW CLOUDS AND VISIBILITIES STUCK UNDERNEATH A RADIATIONAL AND COLD FRONTAL INVERSION (SEE 00Z APX SOUNDING). SO FAR...THE ONLY PLACES AROUND DENSE FOG ADVISORY CRITERIA ARE ESC...MNM...ISQ AND ERY PER OBS. THESE LOW CLOUDS EXTEND INTO EASTERN MN...AND HAVE HELPED TO KEEP TEMPERATURES AND DEWPOINTS UP INTO THE MID TO UPPER 50S. TO THE WEST...LOW PRESSURE HAS DEVELOPED NEAR PIERRE SOUTH DAKOTA DUE TO DOWNSLOPING FLOW OFF THE ROCKIES AND HEIGHT FALLS AHEAD OF THE INTERMOUNTAIN WEST TROUGH. VERY LITTLE IN THE WAY OF PCPN IS OCCURRING ALONG THE LOWS ASSOCIATED COLD FRONT...WITH MOSTLY HIGH CLOUDS PRESENT. THIS IS DUE TO A LOT OF LOW AND MID LEVEL DRY AIR AS SEEN ON THE 00Z NORTH PLATTE NEBRASKA SOUNDING. ANY PCPN AT THE MOMENT WITH THE ENTIRE TROUGH IS FARTHER WEST OVER UTAH AND COLORADO. ALTHOUGH THE PCPN IS FAIRLY MINIMAL...THE SYSTEM IS PRODUCING PLENTY OF WIND...WITH PROFILERS ACROSS NEBRASKA AND WESTERN KANSAS IN THE 40-50KT RANGE AT 850MB. THESE WINDS...MOSTLY FROM THE SSW...ARE TRANSPORTING 850MB DEWPOINTS OF AROUND 10C NORTHWARD FROM WEST TEXAS AND SW KANSAS PER 00Z RAOBS. && .DISCUSSION (ISSUED AT 431 AM EDT)... TODAY AND TONIGHT...MODELS (GFS/NAM/UKMET/CANADIAN) ARE ALL IN GOOD AGREEMENT WITH REGARDS TO THE PROGRESSION AND TIMING OF THE UPPER LEVEL TROUGH AND COLD FRONT MOVING EASTWARD. THEY ALL HAVE TRENDED TOWARDS THE SLOWER IDEA PRESENTED BY THE 00Z NAM/UKMET SHOWN YESTERDAY. BY 00Z WED...THE TROUGH IS PROGGED TO BE OVER CENTRAL MINNESOTA WITH THE COLD FRONT IN WESTERN WI. BY 12Z WED...BOTH THE TROUGH AND FRONT ARE PROGGED TO BE LOCATED OVER EASTERN ONTARIO AND LOWER MICHIGAN...WITH STRONG DRYING COMING IN BEHIND IT. UNTIL THAT OCCURS...THE AREA WILL BE UNDER A WARM ADVECTION PATTERN AHEAD OF THE TROUGH...WHICH SHOULD BRING UP A NARROW ZONE OF 850MB THETA-E ADVECTION INTO THE CWA. WITHIN THIS ZONE...SHOWERS AND SOME THUNDERSTORMS ARE EXPECTED TO DEVELOP AS HEIGHT FALLS COME ACROSS FROM THE UPPER TROUGH. IT APPEARS THIS DEVELOPMENT WILL TAKE PLACE EARLY THIS AFTERNOON OVER MN/WI AND PERHAPS THE FAR WESTERN U.P....THEN GRADUALLY MOVE EASTWARD THROUGH THE AFTERNOON AND NIGHT. BEST CHANCES FOR RAIN APPEARS TO BE TONIGHT...THOUGH...GIVEN THE SLOWER MOTION PROGGED WITH THE TROUGH/COLD FRONT. TEMPERATURES WILL HAVE A HARD TIME WARMING WITH ALL THE CLOUD COVER...BUT SOUTHERLY WINDS SHOULD BE ABLE TO GIVE AT LEAST A 5-10 DEGREE RISE. BUMPED UP LOWS TONIGHT...PARTICULARLY IN THE EAST DUE TO THE SLOWER MOTION OF THE FRONT. WED THROUGH THU...DRY AIR ADVECTION THAT OCCURRED BEHIND TONIGHTS UPPER TROUGH SHOULD SET THE STAGE FOR QUIET WEATHER DURING THIS PERIOD. AN UPPER TROUGH CURRENTLY OVER THE EAST PACIFIC IS PROGGED TO DIG DOWN INTO THE WEST COAST...CAUSING HEIGHT RISES DOWNSTREAM. THESE HEIGHT RISES WILL PROMPT WARM ADVECTION OVER THE AREA...HOWEVER GIVEN THE DRY AIRMASS PRESENT...VERY LITTLE CLOUD COVER IS EXPECTED. ONLY ACROSS ISLE ROYALE AND WESTERN LAKE SUPERIOR WED NIGHT AND THU IS THERE EXPECTED TO BE PARTLY TO MOSTLY CLOUDY SKIES...WHERE THE BEST MOISTURE CONVERGENCE IS PROGGED. THE WARM ADVECTION WILL ALLOW 850MB TEMPS TO CLIMB TO 8C AT 18Z WED AND TO 14C BY 18Z THU. WE SHOULD BE ABLE TO MIX UP TO 850MB ON WED...GIVEN THE COOLER CONDITIONS...AND THUS ALLOW HIGHS TO REACH THE UPPER 60S TO LOW 70S. ON THU...GIVEN THE SUN ANGLE...IT MAY BE HARD TO REACH 850MB...AND THUS HAVE ONLY WENT WITH HIGHS IN THE LOW TO MID 70S. THU NIGHT AND FRI...WARM AND MOIST AIR ADVECTION IS PROGGED TO INCREASE ACROSS THE PLAINS...UPPER MISSISSIPPI VALLEY AND WESTERN GREAT LAKES AS THE TROUGH OVER THE WEST COAST CONTINUES TO DIG TOWARDS THE FOUR CORNERS. LEFT IN SLIGHT CHANCE POPS FOR AFTER 06Z THU NIGHT FOR THE FAR WESTERN U.P. AND WESTERN LAKE SUPERIOR WHERE ENOUGH MOISTENING OF THE LOW AND MID LEVELS TAKE PLACE. CONDITIONS LOOK BETTER FOR PCPN DEVELOPING ON FRI WITH CONTINUED MOISTENING AND THE PROSPECTS OF A SHRTWV OR SHRTWVS CROSSING...AS INDICATED BY THE 00Z ECMWF/GFS. TO GIVE AN IDEA OF THE MOISTENING...850MB DEWPOINTS AT IMT CLIMB FROM -4C AT 00Z FRI TO 12C AT 00Z SAT. HAVE INCREASED POPS TO 40 FOR FRI. FRI NIGHT THROUGH SUN...THIS PERIOD OF THE FORECAST CAN HAVE A LOT OF BUST POTENTIAL...WITH UNCERTAINTIES ABOUT HOW THE WESTERN TROUGH EVOLVES. IT DOES SEEM LIKE...THOUGH...THAT MODELS ARE FOCUSING ONTO MORE RIDGING ACROSS UPPER MICHIGAN WITH THE ONLY EXCEPTION BEING THE 00Z UKMET WHICH IS VERY PROGRESSIVE WITH THE WESTERN TROUGH. THE SCENARIO OF MORE RIDGING...WITH A POSSIBLE FRONTAL BOUNDARY OVER THE AREA SEEMS MORE LIKELY. TO THE SOUTH OF THIS BOUNDARY...WARM AND HUMID CONDITIONS FOR OCTOBER ARE EXPECTED. NORTH OF THE BOUNDARY...COOLER WEATHER WITH SHOWERS AND THUNDERSTORMS SEEM LIKELY WITH 850MB DEWPOINTS AROUND 14C. EITHER WAY...IT WAS NECESSARY TO RAISE TEMPERATURES UP THROUGH THE PERIOD...WITH A SIGNIFICANT INCREASE ON FRI NIGHT WITH A WARM FRONTAL BOUNDARY PROGGED TO BE JUST NORTH OF UPPER MICHIGAN. MORE ADJUSTMENTS TO THE EXTENDED WILL BE NEEDED. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... LIFR/VLIFR CONDITIONS HAVE SETTLED OVER KCMX/KSAW OVER THE LAST FEW HRS. EXPECT THESE CONDITIONS TO LINGER FOR THE NEXT COUPLE OF HRS (ESPECIALLY AT KSAW) BEFORE STRENGTHENING SRLY FLOW DUE TO AN APPROACHING SFC TROF OVER THE PLAINS INCREASES MIXING AND THUS RESULTS IN IMPROVING VIS/CIGS. JUST HOW FAST THE IMPROVEMENT OCCURS WILL BE A CHALLENGE...BUT BY LATE MORNING...EXPECT CONDITIONS TO HAVE IMPROVED INTO THE LWR MVFR RANGE. VFR CONDITIONS MAY PREVAIL FOR MUCH OF THE AFTN THOUGH CONFIDENCE IS NOT GREAT IN COMPLETE DEPARTURE OF MVFR CIGS. COLD FRONT WILL RACE ACROSS UPPER MI TONIGHT...BRINGING A PERIOD OF SHRA TO KCMX/KSAW WITH MVFR/POSSIBLE IFR CONDITIONS. THERE SHOULD BE SOME EMBEDDED THUNDERSTORMS...BUT CONFIDENCE IN THUNDER ACTUALLY OCCURRING AT KCMX/KSAW IS TOO LOW TO INCLUDE IN THIS FCST ISSUANCE. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FCST ISSUANCE)... NEXT ACTIVE LOW PRES TROUGH WILL RACE E FROM THE PLAINS TODAY AND CROSS LAKE SUPERIOR TONIGHT. SRLY WINDS WILL RAMP UP IN ADVANCE OF THIS TROUGH TO GENERALLY 15 TO 25KT...BUT IT`S NOT OUT OF THE QUESTION THAT A FEW GALE FORCE GUSTS TO 35 KT COULD OCCUR OVER THE E HALF OF THE LAKE LATE THIS AFTN/EVENING. W GALE FORCE GUSTS TO 35 KT COULD OCCUR IMMEDIATELY AFTER TROF PASSAGE FROM AROUND THE KEWEENAW PENINSULA EWD LATE TONIGHT/EARLY WED MORNING. WINDS FOR THE REMAINDER OF THE FCST (WED AFTN THRU SAT) SHOULD GENERALLY BE IN THE 10 TO 20KT RANGE WITH AN OCCASIONAL PERIOD OF 15 TO 25KT. && .MQT WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVY UNTIL 11 AM EDT TODAY MIZ004>007-010>014-084-085. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1251 PM CDT TUE OCT 2 2007 .DISCUSSION... ISSUED 1150 AM CDT TUE OCT 2 2007 UPDATED DISCUSSION FOR SPC DAY1 OUTLOOK... SPC HAS RETREATED SLIGHT RISK OF SEVERE STORMS THIS EVENING WEST OF A GALESBURG TO JACKSONVILLE LINE. THIS COVERS SCHUYLER...SCOTT AND THE WESTERN QUARTER OF MORGAN AND CASS COUNTIES. BELOW IS SPC DISCUSSION. PROGRESSIVE SHORTWAVE TROUGH AND ASSOCIATED 50 TO 60 KT MID LEVEL JET EJECTING ACROSS THE CENTRAL PLAINS WILL CONTINUE LIFTING NE ACROSS THE MID/UPPER MS RIVER VALLEY THIS AFTERNOON. THIS WILL ALLOW STRONG SURFACE COLD FRONT FROM FAR EASTERN SD INTO CENTRAL KS TO PUSH ESE INTO CENTRAL IL NEAR THE IL RIVER BY 06Z/1 AM. DESPITE PRESENCE OF HIGH THETA-E AIR/DEWPOINTS IN 60S IN PLACE AHEAD OF THE FRONT...SOME FACTORS REMAIN ACROSS THIS REGION WHICH ARE UNFAVORABLE FOR SEVERE THUNDERSTORMS. THIS INCLUDE THE RATHER WEAK LAPSE RATES SAMPLED ON 12Z SOUNDINGS AND HAVING LARGER SCALE ASCENT LIFTING AWAY FROM MODEST INSTABILITY AXIS OVER ERN KS/WRN MO DURING THE AFTERNOON. MODELS ARE CONSISTENT IN MAINTAINING ONGOING BAND OF THUNDERSTORMS WITH SLOW INCREASE IN COVERAGE AND INTENSITY EXPECTED FROM NE OK INTO SE IOWA THROUGH THE AFTERNOON AS HEATING BOOSTS INSTABILITY. ALTHOUGH LAPSE RATES REMAIN WEAK...MODEST SURFACE HEATING AND VERY MOIST BOUNDARY LAYER SHOULD SUPPORT AXIS OF 1000 TO 1500 J/KG MLCAPE FROM SW OK INTO CENTRAL MO. MLCAPE WILL LIKELY REMAIN NEAR OR BELOW 1000 J/KG INTO THE MID MS RIVER VALLEY. THIS AMOUNT OF INSTABILITY WILL LIKELY SUFFICE FOR INCREASE IN SEVERE THREAT THROUGH LATE AFTERNOON AND EARLY EVENING GIVEN STRONG LOW AND MID LEVEL SHEAR. SHEAR WILL BE STRONGEST FROM THE LOWER MO RIVER VALLEY/OZARK PLATEAU NNE AS 50 KT MID LEVEL JET AND 40+ KT LOW LEVEL JET EJECTS TOWARDS THE WESTERN GREAT LAKES TONIGHT. GREATEST SEVERE THREAT ACROSS THIS AREA WILL DEPEND UPON OVERALL STORM MODE...WITH 150+ SFC TO 1 KM STORM RELEATIVE HELICITY (SRH) AND HIGH BOUNDARY LAYER RH FAVORING A TORNADO THREAT SHOULD SUPERCELLS REMAIN DISCRETE. GIVEN STRONG SE MOVING COLD FRONT ALMOST NORMAL TO EXPECTED STORM MOTIONS...ACTIVITY MAY EVOLVE INTO SMALL LINES AND SUPPORT MAIN THREAT OF ISOLATED DAMAGING WINDS UNTIL STORMS ARE UNDERCUT BY THE COLD FRONT. ACTIVITY SHOULD DEVELOP INTO A BROKEN SQUALL LINE ACROSS THE MID/UPPER MS RIVER VALLEY DURING THE EVENING...ALTHOUGH SEVERE THREAT SHOULD WANE AS ACTIVITY SHIFTS ENE OF MARGINAL INSTABILITY AXIS ACROSS THE IL RIVER VALLEY DURING THIS EVENING. PREVIOUS UPDATED DISCUSSION... FORECAST APPEARS ON TRACK TODAY AND JUST MINOR UPDATES TO THE HOURLY GRIDS ACROSS CENTRAL/SE IL TODAY. A WARMER DAY THANKS TO BREEZY SOUTH WINDS. HIGHS IN THE LOWER TO MIDDLE 80S WITH INCREASING CLOUDS FROM THE WEST. SLIGHT CHANCE OF LATE DAY SHOWERS/THUNDERSTORMS OVER KNOX...FULTON AND SCHUYLER COUNTIES AFTER 4 PM. 15Z/10 AM SURFACE MAP SHOWS ELONGATED/DEEP 999 MB LOW PRESSURE ALONG THE MN/ND BORDER WITH ITS STRONG COLD FRONT EXTENDING SOUTH ACRSS FAR EASTERN SD INTO EASTERN NEBRASKA AND CENTRAL KS. 1032 MB HIGH PRESSURE WAS OFF THE NEW ENGLAND COAST AND RIDGING SW TOWARD TX. IL IN AN INCREASING SOUTHERLY FLOW BETWEEN THESE WX SYSTEMS. CIRRUS CLOUDS HAVE BEEN INCREASING/THICKENING FROM THE WEST EASTERN IL EAST OF I-57 STILL SEEING NEARLY SUNNY SKIES WITH PARTLY TO MOSTLY SUNNY SKIES FROM I-57 WEST. TEMPS WERE IN THE UPPER 60S TO MID 70S WITH DEWPOINTS IN THE UPPER 50S AND LOWER 60S. RUC AND NAM-WRF SIMILAR IN BRING THE COLD FRONT EAST INTO CENTRAL IA AND NW MO BY SUNSET/00Z WHILE QPF NUDGING INTO KNOX...FULTON AND SCHUYLER COUNTIES BETWEEN 4 AND 7 PM. HIGHS SHOULD REACH THE LOWER TO MIDDLE 80S AS CLOUDS INCREASE FROM THE WEST WITH BREEZY SOUTH WINDS GUSTING TO 15 TO 25 MPH. BRUNT OF SHOWERS AND THUNDERSTORMS MOVES INTO CENTRAL IL TONIGHT WITH COLD FRONT NEAR I-55 BY 06Z AND IN SE IL BY 12Z/WED. SPC HAS SLIGHT RISK OF SEVERE STORMS THIS EVENING WEST OF THE IL RIVER FOR MAINLY DAMAGING WIND GUSTS. HUETTL && .AVIATION... ISSUED 1242 PM CDT TUE OCT 2 2007 VFR CONDITIONS TO PREVAIL THROUGH SUNSET ACROSS CENTRAL IL TAF SITES WITH FEW TO SCATTERED CUMULUS CLOUDS AND SCATTERED TO BROKEN MID/UPPER LEVEL CLOUDS INCREASING FROM THE WEST. BREEZY SOUTH WINDS NEAR 15 KTS AND GUSTS OF 20 TO 22 KTS THIS AFTERNOON. SHARP COLD FRONT OVER FAR WESTERN MN...FAR EASTERN NEBRASKA WILL MOVE EAST TOWARD THE IL RIVER BY 06Z/1 AM AND EAST OF I-57 BY 12Z/WED. BAND OF SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF THIS COLD FRONT. HAVE ABOUT A 4 HOUR PERIOD OF CONVECTION TIMED TO REACH PIA BY 02Z... SPI BY 03Z...BMI AND DEC BY 04Z AND CMI BY 05Z/MIDNIGHT. HEAVY RAINS COULD REDUCE VISIBILITIES TO 1.5 TO 2 MILES AND GUSTS WSW WINDS AROUND 35 KTS. BROKEN 2500 CLOUDS TO SCATTERED OUT BETWEEN 11Z AND 15Z WED MORNING WITH WEST WINDS OF 7 OR 8 KTS. HUETTL && .PREV DISCUSSION... ISSUED 330 AM CDT TUE OCT 2 2007 SHORT TERM...TODAY THROUGH THURSDAY. WATER VAPOR IMAGERY SHOWS STRONG SHORTWAVE TROUGH MOVING ACROSS WY/CO THIS MORNING... WITH AN EXPANSIVE PLUME OF MID/UPPER-LEVEL SUBTROPICAL MOISTURE STREAMING OUT AHEAD OF IT... STRETCHING FROM BAJA CALIFORNIA TO THE CENTRAL PLAINS. INTERESTING TO NOTE ALSO THAT THE REMNANTS OF TD JULIETTE WHICH IS CURRENTLY SHEARING OUT ACROSS THE NORTHERN SEA OF CORTEZ... ARE ALSO GETTING CAUGHT UP IN THIS MOIST CONVEYOR BELT. THIS EXTRA MID AND UPPER LEVEL MOISTURE IS PROGGED TO ADVECT INTO THE MISSISSIPPI VALLEY THIS AFTERNOON... RESULTING IN A RAPID INCREASE IN OVERALL MOISTURE... WITH PWAT VALUES NEARING THE 2-INCH MARK BY LATE AFTERNOON ACROSS EASTERN IA/WESTERN ILLINOIS. RESIDUAL LOW LEVEL MOISTURE IS STILL IN PLACE ACROSS THE REGION THIS MORNING... WITH LOW LEVEL DRY AIR NEVER REALLY MAKING IT IN BEHIND YESTERDAYS COLD FRONT. LOWER 70S DEWPOINTS LURK NOT TOO FAR TO THE SOUTH ACROSS OK/AR. NAM/GFS HAVE A GOOD HANDLE ON LOW LEVEL MOISTURE... AND SUGGEST A NARROW PLUME OF UPPER 60S DEWPOINTS ADVECTING INTO THE MISSISSIPPI VALLEY AHEAD OF THE COLD FRONT THIS AFTERNOON. CONVECTION SHOULD INITIATE EARLY THIS AFTERNOON ACROSS WESTERN IA/MO AHEAD OF A PREFRONTAL TROUGH CURRENTLY OVER EASTERN COLORADO. MAIN SHORTWAVE AND ATTENDANT COLD FRONT WILL QUICKLY CATCH UP TO THE INITIAL CONVECTION... AND THIS ADDED LARGE SCALE FORCING WILL LIKELY HELP THE CONVECTION TRANSITION TO MORE OF A LINEAR MODE. THE PROBLEM FOR US WILL BE THE POTENTIAL LACK OF INSTABILITY COUPLED WITH THE TIMING OF THE FROPA. WHILE THE MID/UPPER LEVEL MOISTURE PLUME WILL INCREASE PWAT VALUES ACROSS THE REGION... IT WILL ALSO RESULT IN WIDESPREAD MID/HIGH LEVEL CLOUD COVER ACROSS THE REGION... ALREADY SEEN IN SATELLITE IMAGERY ACROSS IOWA AND THE GREAT PLAINS. THIS MOISTURE WILL ALSO RESULT IN SHODDY MID- LEVEL LAPSE RATES... FURTHER DECREASING OVERALL CONVECTIVE INSTABILITY. HOWEVER... IT APPEARS STRONG SHEAR AND FORCING WILL MAKE UP FOR THIS LACK OF INSTABILITY... AT LEAST EARLY ON. CONTINUED TO KEEP POPS MAINLY CONTAINED TO AFTER 00Z... EXCEPT FOR A SLIGHT CHANCE IN THE EXTREME FAR WEST. OVERALL UPPER PATTERN SUGGESTS TWO PRIMARY AREAS FOR HEAVIER CONVECTION/QPF WILL BE FAVORED. ONE ACROSS EASTERN IOWA AND NORTHWESTERN ILLINOIS... WHICH WILL BE IN THE RRQ OF A 90-100KT JET STREAK AND CLOSER TO THE SHORTWAVE ENERGY AS IT LIFTS ACROSS WISCONSIN. THE SECOND AREA WILL LIKELY BE ACROSS THE LOWER MISSISSIPPI VALLEY WHERE OVERALL CONVECTIVE INSTABILITY WILL BE MUCH HIGHER. HIGHEST POPS ARE IN THE WEST FOR THIS EVENING... AS STRONG FORCING HELPS TO MAINTAIN STRONG CONVECTION AS IT CROSSES INTO WESTERN ILLINOIS. THIS UPPER LEVEL SUPPORT WILL QUICKLY OUTRACE THE THE CONVECTION BY MIDNIGHT... RESULTING IN A RAPID WEAKENING TREND AS THE STORMS LOSE THEIR SUPPORT AT LEAST THIS FAR SOUTH. THUS EXPECT OVERALL LOWER PRECIP COVERAGE AND QPF ACROSS EASTERN ILLINOIS. AREAS OF SOUTHEAST ILLINOIS MAY BENEFIT FROM SLIGHTLY HIGHER INSTABILITY AND COULD BE ON THE EASTERN EDGE OF THE AFOREMENTIONED SECOND FAVORED AREA FOR CONVECTION. SVR THREAT WILL MAINLY BE WIND... EXPECTING PRIMARILY LINEAR CONVECTION WITH BOWING SEGMENTS... BUT ISOLATED BOW ECHO TORNADOES ARE NOT OUT OF THE QUESTION... ESPECIALLY GIVEN SUCH IMPRESSIVE SHEAR PARAMETERS ACROSS EASTERN ILLINOIS BETWEEN 00 AND 03Z. 0-6KM SHEAR OF AROUND 50KTS... AND 0-1KM SHEAR OF 20-30KTS. COULD SEE SOME LINGERING SHOWERS ACROSS THE FAR EAST WEDNESDAY MORNING... BUT WILL ONLY HOLD ON TO A SLIGHT CHANCE FOR NOW... ESPECIALLY CONSIDERING HOW QUICKLY THE LAST SYSTEM DEPARTED. DRY CONDITIONS SHOULD LAST THROUGH WED AND THURSDAY UNDER ZONAL FLOW. LONG TERM...FRIDAY THROUGH MONDAY. ZONAL FLOW PATTERN WILL QUICKLY BECOME MORE AMPLIFIED BY THE END OF THE WORK WEEK... WITH A BROAD DIGGING TROUGH ACROSS THE WEST COAST AND BUILDING HEIGHTS ACROSS THE EASTERN CONUS. GFS HAS BEEN FLIP- FLOPPING OVER THE PAST 3 DAYS TRYING TO FIGURE OUT HOW QUICKLY TO CARRY THE WESTERN TROUGH WESTWARD. CONSIDERING THE LONG WAVELENGTH OF THE TROUGH AND THE RIDGING TO ITS EAST... WILL CONTINUE TO FAVOR THE SLOWER GUIDANCE... ESPECIALLY THE MORE CONSISTENT ECMWF AND CANADIAN GEM GLOBAL. WITH SOUTHWESTERLY FLOW IN PLACE... TEMPERATURES WILL REMAIN WELL ABOVE NORMAL... IN THE 80S. CANNOT OUTRULE SOME SCATTERED CONVECTION BECOMING AN ISSUE BY FRIDAY AND SATURDAY AFTERNOONS... ESPECIALLY IF ANY WEAK DISTURBANCES EJECT OUT OF THE MAIN TROUGH AND INTO THE PLAINS STATES... AS HAS BEEN SUGGESTED BY THE GFS/ECMWF/GEM OVER THE PAST FEW DAYS. THE GULF LOOKS TO BE WIDE OPEN DURING THIS PERIOD... WITH A SUSTAINED PERIOD OF RETURN MOISTURE FLOW. HOWEVER... PRECIP CHANCES ARE STILL TOO LOW TO BE MENTIONABLE AT THIS POINT... GIVEN THE UNCERTAINTIES WITH THE TIMING AND THE SUBTLE NATURE OF ANY POTENTIAL DISTURBANCES. ANY CONVECTION WOULD LIKELY FAVOR AREAS WEST OF THE MISSISSIPPI DURING THIS TIMEFRAME AS WELL... CLOSER TO THE LOW LEVEL JET. HARDIMAN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 1147 AM CDT TUE OCT 2 2007 .UPDATE... WIDESPREAD ELEVATED THUNDERSTORMS OCCURRING ALONG AXIS OF STRONG WARM ADVECTION AT 850 MB ACROSS CENTRAL IOWA WERE NOT WELL HANDLED BY 12Z MODELS. THESE CONTINUE TO DRIFT E-NE AND WILL BE ENTERING FAR NW COUNTIES OVER NOON HOUR AND MUCH OF IA W OF HWY 218 BY MID AFTERNOON. HAVE UPDATED GRIDS/ZONES TO SPEED UP ONSET OF THIS PRECIPITATION FOR LATE MORNING AND AFTERNOON. HOW LONG THIS ELEVATED CONVECTION PERSISTS AND THE AMOUNT OF MID AND HIGH CLOUDS IT CONTINUES TO SPEW E-NE OVER CWA TO LIMIT INSOLATION WILL BE CRITICAL TO SEVERE POTENTIAL LATER THIS AFTERNOON. EVEN MOST CONSERVATIVE RUC HAS 65 DEGREE DEWPOINTS CURRENTLY OVER EASTERN KS AND WESTERN MO OVERSPREADING MUCH OF EASTERN IA AHEAD OF THE COLD FRONT TOWARD 00Z WHEN WIND SHEAR IS MAXIMIZED AND MOST FAVORABLE. TRENDS ON VISIBLE SATELLITE SHOW THINNEST CI AND POTENTIAL FOR SURFACE HEATING OVER NE MO...FAR SOUTHEAST IA AND ADJACENT W CENTRAL IL. THUS...BEST SEVERE POTENTIAL LOOKS LIMITED TO THIS AREA FOR LATE AFTERNOON AND EARLY EVENING. SPC IN AGREEMENT WITH THIS THINKING...WITH NEW DAY ONE SLIGHT RISK NOW CONFINED TO SE IA...NE MO AND W CENTRAL IL. && .AVIATION... LARGE AREA OF THUNDERSTORMS OVER CENTRAL IOWA WILL OVERSPREAD EASTERN IOWA THIS AFTERNOON. MVFR CIGS AND CIGS AND VISIBILITIES WILL DEVELOP INTO THE CID SITE EARLY AFTERNOON...REACHING DBQ...MLI AND BRL FROM MID TO LATE AFTERNOON. THERE IS A POTENTIAL FOR SOME STRONG STORMS WITH SURFACE WIND GUSTS UP TO 40KTS AND ISOLATED SEVERE STORMS WITH SMALL HAIL AND DAMAGING WIND GUSTS OVER 50KTS. OUTSIDE OF STORMS...SOUTHWEST WINDS WILL INCREASE TO 15 TO 25 MPH RANGE BY MID AFTERNOON WITH BRIEF HIGHER GUSTS. A COLD FRONT WILL PUSH EAST ACROSS THE AREA THIS EVENING SWEEPING THUNDERSTORMS OUT OF THE AREA AND VEERING WINDS TO THE NORTHWEST. THE FRONT WILL ALSO IMPROVE CONDITIONS TO VFR CRITERIA. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SHEETS ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 315 PM CDT TUE OCT 2 2007 .DISCUSSION... ACTIVE PATTERN CONTINUES... SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE ACROSS THE CWA THROUGH THE REST OF THE AFTERNOON. CURRENTLY SEEING BACK EDGE OF PRECIP IN ASSOCIATION WITH MID LEVEL COOL FRONT/TROUGH AXIS MOVING INTO FAR WESTERN MINNESOTA. THE BACK EDGE SHOULD REACH THE EASTERN CWA AROUND 00Z WITH PRECIP ENDING ACROSS THE WISCONSIN COUNTIES AROUND 04Z OR SO. CLOUD COVER WILL ALSO SHARPLY DECREASE FROM WEST TO EAST THROUGH THE LATE EVENING AS DRYING WORKS IN. MAY SEE SOME LOW STRATUS LINGER ACROSS THE FAR EASTERN CWA TOWARDS DAYBREAK. WINDS WILL REMAIN ELEVATED AS TIGHT PRESSURE GRADIENT REMAINS IN PLACE THROUGH THE EARLY EVENING BUT WEAK RIDGING BUILDS IN OVERNIGHT. A SHORT WAVE TROUGH OVER WESTERN ALBERTA MOVES EASTWARD WELL NORTH OF THE AREA THROUGH WEDNESDAY EVENING. A SFC LOW ALSO MOVES ACROSS SOUTHERN CANADA ALLOWING THE PRESSURE GRADIENT TO TIGHTEN ACROSS THE UPPER MIDWEST. THIS BRINGS A QUICK RETURN OF SOUTHWEST WINDS ACROSS THE CWA DURING THE DAY. HAVE WARMED TEMPERATURES A FEW DEGREES TO TAKE INTO ACCOUNT LOCAL DOWNSLOPING WITH THE GUSTY SOUTH/SOUTHWEST WINDS. MILD AIR REMAINS IN PLACE WITH DRY CONDITIONS EXPECTED INTO THURSDAY. LOW AMPLITUDE TROUGH OVER THE EASTERN PACIFIC OFF THE WEST COAST OF CANADA WILL DEEPEN OVER THE NEXT SEVERAL DAYS AS IT COMES ONSHORE INTO THE WESTERN UNITED STATES. MUCH UNCERTAINTY EXISTS WITH THE EVOLUTION OF THIS FEATURE THROUGH THE FORECAST PERIOD. THIS WILL BE DISCUSSED BELOW. IN THE MEANTIME...EXPECT A WARM FRONT TO DEVELOP FROM SOUTHWEST TO NORTHEAST ACROSS THE CENTRAL PLAINS AND INTO CENTRAL MINNESOTA LATE THURSDAY AND FRIDAY AS SFC LOW PRESSURE TAKES SHAPE IN THE LEE OF THE ROCKIES. INDICATIONS ARE THAT MOISTURE TRANSPORT INCREASES SIGNIFICANTLY LATER THURSDAY AND INTO FRIDAY AS GULF OF MEXICO OPENS UP ON BACKSIDE OF HIGH PRESSURE OVER THE ATLANTIC. AN UPPER SPEED MAX IS ALSO EXPECTED TO NOSE INTO THE AREA AS WELL. RIGHT NOW FRIDAY IS SHAPING UP TO BE A WET DAY. FROM THERE...WARM FRONT IS EXPECTED TO BE TO THE NORTHWEST OF THE AREA FOR SATURDAY. THERE IS UNCERTAINTY IN ITS POSITION SO LOW POPS HAVE BEEN RETAINED FOR NOW BUT SATURDAY MAY END UP BEING RELATIVELY DRY AND POTENTIALLY VERY WARM AS MID LEVEL WARM AIR INCREASES. FROM THERE THE CONFIDENCE DECREASES IN THE FORECAST AS MENTIONED BELOW. CONFIDENCE HAS DECREASED IN THE MEDIUM RANGE OF THE FORECAST...ESPECIALLY THROUGH THE UPCOMING WEEKEND AND EARLY NEXT WEEK. MODELS HAVE COME IN WITH VERY DIFFERENT SOLUTIONS THAN SEEN YESTERDAY. OVERALL PROGRESSION OF APPROACHING LONGWAVE UPPER TROUGH IS SLOWER. GFS AND ECMWF ARE CONSISTENT IN THAT THEY BOTH SHOW THE SAME BIG CHANGE WITH DIFFERENCES REMAINING IN TIMING AND LOCATION OF FEATURES. AS FOR THE DETAILS...BROAD UPPER TROUGH OFF THE CANADIAN WEST COAST AMPLIFIES OVER THE NEXT FEW DAYS AS IT APPROACHES THE U.S. WEST COAST AS PREVIOUSLY MENTIONED. THE CHANGE COMES IN THAT THIS LOW IS NOW FORECAST TO CUT OFF OVER THE SOUTHWEST U.S. SETTING UP BROAD SOUTHWEST FLOW ALOFT OVER THE CENTRAL U.S. THROUGH THE END OF THE WEEK. THIS SCENARIO HAS MAJOR IMPLICATIONS ON THE FORECAST. NAMELY...THE WEEKEND WOULD REMAIN WARMER...AND POTENTIALLY DRIER THAN PREVIOUSLY THOUGHT /SATURDAY ESPECIALLY/ DEPENDING WHERE THE FRONT GETS HUNG UP. AT THIS POINT SUNDAY WOULD SEE A RETURN OF PRECIPITATION AS UPPER LOW EJECTS NORTHEASTWARD BUT THIS MAY STILL NEED TO BE SLOWED. CONFIDENCE IS LOW SINCE THIS BIG CHANGE HAS JUST OCCURRED BUT HAVE TRENDED IN THE DIRECTION OF A SLOWER PROGRESSION WITH THE LOW CUTTING OFF. MAY CONTINUE TO SEE LARGE CHANGES OVER THE NEXT FEW MODEL RUNS. HEMISPHERIC SATELLITE IMAGERY SHOWS A TROUGH NEAR 45N AND 150E TODAY. THE MODELS APPEAR TO BE HAVING DIFFICULTY HANDLING THE EVOLUTION OF THIS FEATURE AS IT NEARS ALASKA LATER THIS WEEK...OR ABOUT THE TIME WHEN THE PACIFIC TROUGH REACHES THE WEST COAST. THIS APPEARS TO HAVE AN EFFECT ON WHETHER THE LOW CUTS OFF AS SOON AS IT IS NOW FORECAST TO OR WAITS AND STAYS OPEN LONGER AS RUNS FROM THE PAST FEW DAYS HAD SHOWN. ANOTHER IMPLICATION OF THE LOW CUTTING OFF IS THAT LESS COOLER AIR WILL DROP TOWARDS THE REGION BECAUSE ZONAL FLOW SETS UP ACROSS SOUTHERN CANADA AS OPPOSED TO THE HIGHLY AMPLIFIED PATTERN ADVERTISED EARLIER. ..MDB.. && .AVIATION.../18Z TAFS/ CONCERN WITH THE TAFS ARE SHOWERS AND MVFR CIGS THIS AFTN INTO THIS EVE. SURFACE COLD FRONT...ALMOST MORE OF A DRYLINE...WILL MOVE FROM WRN MN TO THE MN/WI BORDER BY 00Z. WINDS WILL SHIFT QUICKLY FROM SOUTHERLY TO WEST NORTHWEST WITH FROPA...WITH GUSTS BOTH IN ADVANCE AND BEHIND OF THE FRONT REACHING UP TO AS HIGH AS 25 KTS. SHOWERS WILL CONTINUE TO DEVELOP THROUGHOUT THE AREA...INCLUDING BEHIND THE SURFACE FRONT...AS DEEP MOISTURE REMAINS UNDER BROAD SCALE ASCENT. SO TEMPOS GENERALLY PREVAILING THIS AFTN. EMBEDDED MCV PASSING OVER STC WILL OFFER THE BEST CHANCE FOR THUNDER...POSSIBLY SPREADING DOWN TOWARDS MSP. MVFR CIGS SHOULD MOVE ACROSS SRN AND ERN MN AND WRN WI AS INDICATED BY RUC MODEL 950 AND 925MB MOISTURE FIELDS CORRELATING WELL WITH SATELLITE TRENDS. THOUGH CLOUDS WILL BE SLOW TO SCOUR FROM WEST TO EAST TONIGHT...PRESSURE RISES AND DRY AIR ARE FAIRLY SUBSTANTIAL IN THE DAKOTAS SO THE FORECAST THOUGHT IS THAT THEY INDEED WILL SCOUR TONIGHT...EXCEPT FOR EAU. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MDB/MTF mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 103 PM CDT TUE OCT 2 2007 .DISCUSSION... SURFACE LOW PRESSURE OVER ND EARLY THIS MORNING WITH A COLD FRONT TRAILING SOUTH THROUGH EASTERN CO. SYSTEM TO PROGRESS RATHER QUICKLY TO THE EAST TODAY...WITH THE COLD FRONT EXPECTED TO BE EAST OF KEAU BY THIS EVENING. MAIN CONCERN TODAY IS POTENTIAL FOR HEAVY RAIN OVER SE MN AND WEST CENTRAL WI. VIGOROUS UPPER TROF OVER THE WESTERN HIGH PLAINS ATTM. AS THIS FEATURE MOVES INTO THE NORTHERN PLAINS THIS MORNING...A COUPLED JET STRUCTURE DEVELOPS OVER SOUTHERN MN AND IA BY EARLY THIS AFTERNOON. GFS DIFFERENTIAL LAYER DIVERGENCE QUITE IMPRESSIVE FROM KMSP TO KDSM. PRECIPITABLE WATER VALUES PROJECTED BY THE GFS TO INCREASE NEARLY THREE QUARTERS OF AN INCH BETWEEN 12Z AND 18Z OVER THE EASTERN CWA WITH A PW VALUE AROUND 1.5 INCHES EXPECTED BY EARLY THIS AFTERNOON. THIS IS MORE THAN 2 STANDARD DEVIATIONS ABOVE NORMAL. HAVE INSERTED HEAVY RAIN INTO THE FORECAST FOR TODAY FOR EASTERN AREAS WITH POPS FROM 80 TO 100 PERCENT. SUBTROPICAL JET IS ALSO BRINGING HIGH LEVEL MOISTURE FROM THE REMAINS OF JULIETTE INTO THE CENTRAL PLAINS. PRECIPITATION ANALYSIS PAGE SHOWING A SWATH OF 2 TO 4 INCHES OF OBSERVED PRECIPITATION IN THE PAST 7 DAYS FROM FARIBAULT AND FREEBORN COUNTIES ON NORTHEAST ACROSS RUSK...CHIPPEWA AND EAU CLAIRE COUNTIES. CONSIDERED A FFA FOR TODAY...BUT PROGRESSIVE NATURE OF SYSTEM SHOULD KEEP AMOUNTS TO AN INCH. THE DAY SHIFT WILL HAVE TO KEEP AN EYE OUT FOR INDICATIONS THAT THE SYSTEM IS NOT PROGRESSING AS FAST AS FORECAST. BEYOND TODAY...MUCH BETTER WEATHER FOR WEDNESDAY AND THURSDAY AS A MILD WESTERLY FLOW OCCURS. BIG CHANGE WITH THE GFS OVER THE PAST THREE RUNS WITH REGARDS TO THE WEEKEND WEATHER MAKER. CLOSED 500MB LOW SUNDAY MORNING OVER EASTERN IA ON THE 01/12Z RUN IS NOW OVER THE PANHANDLE OF NEBRASKA ON THE 02/00Z RUN. THIS HAS HUGE IMPLICATIONS TO THE FORECAST. HOWEVER...THIS PERIOD (DAYS 6 AND 7) ARE NOT TOUCHED ON THE MIDNIGHT SHIFT. THE DAY SHIFT WILL HAVE TO MAKE SOME REVISIONS. FOR COMPARISON...THE ECMWF FROM 01/00Z INDICATED AN UPPER TROF OVER THE CENTRAL PLAINS. THE 02/00Z RUN HAS A CLOSED LOW OVER NEBRASKA. SO IT APPEARS THE GFS IS HEADING IN THE RIGHT DIRECTION. IMPLICATIONS WOULD BE A WARMER AND NOT AS WET WEEKEND. && .AVIATION.../18Z TAFS/ CONCERN WITH THE TAFS ARE SHOWERS AND MVFR CIGS THIS AFTN INTO THIS EVE. SURFACE COLD FRONT...ALMOST MORE OF A DRYLINE...WILL MOVE FROM WRN MN TO THE MN/WI BORDER BY 00Z. WINDS WILL SHIFT QUICKLY FROM SOUTHERLY TO WEST NORTHWEST WITH FROPA...WITH GUSTS BOTH IN ADVANCE AND BEHIND OF THE FRONT REACHING UP TO AS HIGH AS 25 KTS. SHOWERS WILL CONTINUE TO DEVELOP THROUGHOUT THE AREA...INCLUDING BEHIND THE SURFACE FRONT...AS DEEP MOISTURE REMAINS UNDER BROAD SCALE ASCENT. SO TEMPOS GENERALLY PREVAILING THIS AFTN. EMBEDDED MCV PASSING OVER STC WILL OFFER THE BEST CHANCE FOR THUNDER...POSSIBLY SPREADING DOWN TOWARDS MSP. MVFR CIGS SHOULD MOVE ACROSS SRN AND ERN MN AND WRN WI AS INDICATED BY RUC MODEL 950 AND 925MB MOISTURE FIELDS CORRELATING WELL WITH SATELLITE TRENDS. THOUGH CLOUDS WILL BE SLOW TO SCOUR FROM WEST TO EAST TONIGHT...PRESSURE RISES AND DRY AIR ARE FAIRLY SUBSTANTIAL IN THE DAKOTAS SO THE FORECAST THOUGHT IS THAT THEY INDEED WILL SCOUR TONIGHT...EXCEPT FOR EAU. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ RAH/MTF mn