AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 242 PM MDT THU SEP 18 2008 .SHORT TERM... (TONIGHT-FRIDAY) CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING GENERALLY WEAK WESTERLY FLOW ALOFT ACROSS THE REGION AS BROAD UPPER RIDGE ACROSS THE ROCKIES FLATTENS OVERHEAD AS A WEAKENING SHORT WAVE CONTINUES TO TRANSLATE ACROSS THE NORTHERN ROCKIES. REGIONAL RADAR AND SATELLITE INDICATING ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ACROSS MTS WITH BEST COVERAGE ACROSS THE NORTHERN AND CENTRAL MTS ATTM. AT SFC...LEE TROUGH DEEPENING ACROSS THE I-25 CORRIDOR WITH GUSTY SOUTH WINDS OF 15 TO 30 MPH ACROSS THE FAR EASTERN PLAINS ATTM. TONIGHT AND FRIDAY...WEAK SHORT WAVE TO CONTINUE TO TRANSLATE ACROSS THE NORTHERN ROCKIES TONIGHT WITH UPPER RIDGING REBUILDING ACROSS THE GREAT BASIN AND INTO WESTERN COLORADO THROUGH FRIDAY AFTERNOON AS THE NEXT EASTERN PAC SYSTEM CONTINUES TO MOVE ONSHORE ACROSS THE WEST COAST. INCREASED AVAILABLE MOISTURE AND MINOR DISTURBANCE EMBEDDED IN THE WESTERLY FLOW TO HELP KEEP CONVECTION ONGOING ACROSS THE HIGHER TERRAIN THROUGH THE EARLY EVENING BEFORE DIMINISHING THROUGH THE MIDNIGHT WITH BEST COVERAGE ACROSS THE CENTRAL MTS. THE WEAK WESTERLY FLOW TO HELP PUSH A FEW STORMS ACROSS THE IMMEDIATE ADJACENT PLAINS...THOUGH WITH CONTINUED DRY LOW LEVELS AND INVERTED V PROFILES...WOULD EXPECT ONLY A FEW SPRINKLES AND GUSTY WINDS UP TO 40 MPH ALONG AND WEST OF THE I-25 CORRIDOR WITH DRY CONDITIONS CONTINUING ACROSS THE REST OF THE PLAINS. PASSING WAVE KICKS LEE TROUGH ACROSS THE FAR EASTERN PLAINS TONIGHT ALLOWING FOR A WEAK NORTHERLY SURGE OVERNIGHT. LOW LEVEL FLOW BECOMES MORE EASTERLY INTO FRIDAY AFTERNOON AND ALONG WITH SLIGHT COOLING ALOFT...SHOULD SEE SLIGHTLY COOLER HIGHS ACROSS THE AREA TOMORROW. ENOUGH MOISTURE CONTINUES TO BE PRESENT UNDER THE RIDGE FOR CONTINUED CHANCES FOR MAINLY ISOLATED CONVECTION ACROSS THE HIGHER TERRAIN ONCE AGAIN. -MW .LONG TERM... ...NOT TOO MUCH CHANGE... LONG RANGE GUIDANCE CONTINUES TO PAINT A RATHER WARM AND DRY PICTURE OVER THE REGION FOR THE NEXT SEVERAL DAYS. TWO TROUGHS ARE FCST TO AFFECT THE REGION. THE FIRST WILL BE THIS WEEKEND (SAT NITE/EARLY SUN) AND THE 2ND WILL BE TUESDAY. ATTM...BOTH THESE TROUGHS APPEAR TO BE PROGRESSIVE AND MAINLY TO THE N OF THE REGION...WITH THE 2ND ONE A BIT STRONGER THAN THE 1ST. THE 1ST TROUGH WILL HAVE MINIMAL AFFECT ON TEMPERATURES WHILE THE 2ND ONE IS FCST TO KNOCK TEMPS DOWN ABOUT 10 DEGREES. AS FOR PRECIP...I BELIEVE THE ONLY PRECIP WILL FALL ACROSS THE CONTDVD WITH BOTH OF THESE SYSTEMS. THE PRECIP IS NOT EXPECTED TO AMOUNT TO MUCH. OTHERWISE...EXPECT CONTINUED WARM AND DRY CONDITIONS ACROSS THE REGION WITH ONLY AN ISOLATED CHANCE OF PRECIP OVER THE HIGH COUNTRY. IF WE DO NOT GET ANY SIGNFICANT PRECIP SOON...THEN WE MAY HAVE TO START WORRYING ABOUT FIRE WX CONCERNS ONCE AGAIN. /HODANISH && .AVIATION... VFR CONDITIONS EXPECTED TO CONTINUE AT ALL TAF SITES FOR THE NEXT 24 HOURS. MAINLY ISOLATED SHOWERS AND THUNDERSTORMS TO CONTINUE THROUGH LATE AFTERNOON AND EARLY EVENING ACROSS THE MOUNTAINS AND IMMEDIATE ADJACENT PLAINS...THOUGH DOES NOT LOOK TO AFFECT AREAS ALONG AND EAST OF I-25 ATTM. -MW && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/34 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 151 AM EDT THU SEP 18 2008 .SYNOPSIS... HIGH PRESSURE WILL BUILD SOUTHWARD OVER THE AREA THURSDAY. THIS WILL PUSH THE FRONTAL BOUNDARY FARTHER TO THE SOUTH AND BRING DRIER AIR TO THE AREA. THIS HIGH PRESSURE AREA WILL CONTINUE FRIDAY AND SATURDAY WITH NICE AUTUMN LIKE WEATHER. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... UPDATE...LOW CLOUDS LINGERING ACROSS THE MIDLANDS. LATEST RUC MODEL SUGGEST THESE CLOUDS MAY CONTINUE LONGER OVERNIGHT THAN PREVIOUS GUIDANCE...ALTHOUGH WITH SHORT WAVE MOVING THROUGH...CLOUDS SHOULD CONTINUE TO THIN. TEMPERATURE FORECAST ADJUSTED SLIGHTLY UPWARD DUE TO LINGERING CLOUDS. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... BOTH NAM AND GFS SHOW UPPER TROUGH ALONG THE EAST COAST THURSDAY AND THURSDAY NIGHT. MID LEVEL HIGH MOVES EAST BUT REMAINS NORTH OF AREA THURSDAY THROUGH FRIDAY NIGHT. THIS SHOULD KEEP HIGH PRESSURE OVER THE AREA FOR THE PERIOD AND ALSO KEEP THE OLD FRONTAL BOUNDARY WELL TO THE SOUTH AND EAST OF THE AREA. IT LOOKS LIKE AN EARLY TOUCH OF AUTUMN IN THE AIR WITH HIGHS IN THE LOWER 80S AND LOW TEMPERATURES 55-60. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... GFS AND ECMWF ARE IN GOOD AGREEMENT DURING EXTENDED. AGREE WITH BOTH MODELS SHOWING NO SIGNIFICANT WEATHER FEATURES OVER THE AREA. A WEAK UPPER TROUGH OUT WEST SATURDAY WEAKENS AND FILLS BY SUNDAY. THEN AN UPPER RIDGE MOVES EAST OVER AREA MONDAY AND TUESDAY AND CONTINUES WEDNESDAY. AT THE SURFACE...THE EAST COAST SURFACE HIGH REMAINS IN CONTROL OF THE WEATHER WITH NORTHEAST SURFACE WINDS. MODELS DO FLATTEN THIS HIGH OUT A BIT BY SUNDAY ALLOWING A MORE EASTERLY WIND FLOW AND ALSO ALLOWING THE WEAK SURFACE BOUNDARY TO APPROACH THE COAST AGAIN BUT MAINLY THE SOUTHERN COAST. SO FOR THE SOUTHEAST PART OF THE AREA DECIDED TO INCLUDE A SLIGHT CHANCE OF SHOWERS SUNDAY THROUGH WEDNESDAY SINCE THERE ARE NO OTHER WEATHER FEATURES THAT WILL PUSH THE FRONT AWAY. STILL PLEASANT TEMPERATURES WITH HIGHS IN THE UPPER 70S TO LOWER 80S. LOWS IN THE UPPER 50S TO LOWER 60S. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... A WEAK SHORTWAVE PASSING OVER THE MIDLANDS AT THIS TIME WILL RESULT IN SUBSIDENCE LATER THIS MORNING. WSR-88D VWP ANALYSIS SHOWS PERSISTENT NORTHEASTERLY FLOW THROUGH ABOUT 2KM...WHICH WILL CONTINUE TO USHER IN DRIER AIR OVER THE MIDLANDS. SATELLITE IMAGERY SHOWING SCT-BKN MID LEVEL CLOUDS WITH LOWER VFR CEILINGS IN THE AGS/DNL AREA. EXPECT CLOUDS TO GRADUALLY DECREASE TOWARDS DAWN BEFORE BEING REPLACED BY FAIR WEATHER CUMULUS THIS AFTERNOON. WINDS WILL PICK UP FROM THE NORTHEAST AT AROUND 5 TO 10 KNOTS BY LATE MORNING AND DIMINISH AROUND SUNSET WITH HIGH PRESSURE REMAINING IN CONTROL AT THE SURFACE. EXTENDED OUTLOOK...BRIEF MVFR CONDITIONS WILL BE POSSIBLE IN LOW LYING AREAS FRIDAY MORNING. OTHERWISE NO SIGNIFICANT IMPACTS TO AVIATION EXPECTED FRIDAY THROUGH MONDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ AVIATION...HC ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 123 PM CDT THU SEP 18 2008 .DISCUSSION... ISSUED 1052 AM CDT THU SEP 18 2008 HIGH PRESSURE RIDGE OVER IL THIS MORNING. PLENTY OF SUN PULLING TEMPS UP INTO THE LOWER 70S EARLY. FORECAST FOR SUNNY SKIES MAY ACTUALLY HAVE A LITTLE BIT OF A PROBLEM AS THE LLVL MOISTURE PROFILE HAS CHANGED SINCE THE OVERNIGHT MODEL RUNS. THIS MORNING...NAM/GFS/NGM/RUC CU RULES ALL HAVE SIGNIFICANT CU THIS AFTERNOON. HAVE UPDATED MAINLY FOR WRN HALF OF CWA...WEST OF RIDGE AXIS...BUT ONLY IN MODERATION FOR NOW. BOOSTED TEMPS ONLY SLIGHTLY AS 850MB TEMPS THIS MORNING UP A DEGREE FROM YESTERDAYS SOUNDING AT 12Z...JUST A TOUCH OVER YESTERDAYS. ALL FORECAST CHANGES ARE SO SUBTLE THAT NO ZONE UPDATES ARE ANTICIPATED AT THIS TIME. && .AVIATION... ISSUED 118 PM CDT THU SEP 18 2008 HIGH PRESSURE REMAINS THE MAIN STORY...BUT SLIDING OFF TO THE EAST. FEW CU FOR THE AFTERNOON...THEN SCT CIRRUS AT MOST IN THE OVERNIGHT. VFR CIGS AND E/SERLY FLOW EXPECTED THROUGH THE OVERNIGHT. PRE DAWN VISBY DROPS SHOULD REMAIN IN MVFR CATEGORY...AND ONLY BRIEFLY BEFORE THE SUNRISE. WINDS MORE SOUTHERLY TOMORROW MORNING AND MINIMAL...IF ANY...CLOUDS. HJS && .PREV DISCUSSION... ISSUED 139 AM CDT THU SEP 18 2008 DRY AND PLEASANT LATE SUMMER WEATHER EXPECTED THROUGH THE ENTIRE FORECAST PERIOD. 06Z SURFACE ANALYSIS SHOWS HIGH PRESSURE CENTERED OVER LAKE SUPERIOR...WITH WEAK FRONTAL BOUNDARY SLOWLY SINKING SOUTHWARD INTO NORTH-CENTRAL ILLINOIS. ALOFT...MAIN STORM TRACK REMAINS WELL TO THE NORTH ACROSS CANADA...WHILE VERY WEAK FLOW DOMINATES ACROSS MUCH OF THE CONUS. SHORT TERM...TODAY THROUGH SATURDAY WEAK FRONT WILL CONTINUE TO DROP SOUTHWARD TODAY...EVENTUALLY STALLING AND WASHING OUT ACROSS CENTRAL ILLINOIS. BOUNDARY WILL BE COMPLETELY MOISTURE-STARVED...SO NOT EXPECTING MUCH IN THE WAY OF CLOUD COVER WITH IT. CU-RULE INDICATES FEW-SCT CU ALONG AND AHEAD OF THE FRONT...MAINLY ACROSS IOWA INTO THE NORTHWEST KILX CWA. BOTTOM LINE WILL BE SUNNY SKIES ACROSS THE BOARD...WITH LIGHT E/NE WINDS. VERY LITTLE IN THE WAY OF CAA BEHIND FRONT...SO HIGH TEMPS WILL BE QUITE SIMILAR TO YESTERDAY...PERHAPS A DEGREE OR TWO COOLER...WITH READINGS REACHING THE UPPER 70S TO AROUND 80 DEGREES. WEAK UPPER LOW CURRENTLY ACROSS THE SOUTHERN ROCKIES WILL SLOWLY TRACK EASTWARD INTO THE LOWER MISSISSIPPI RIVER VALLEY FRIDAY AND SATURDAY. BOTH THE NAM-WRF AND GFS ARE TRYING TO GENERATE SOME PRECIP WITH THIS SYSTEM ACROSS PARTS OF MISSOURI AND SOUTHERN ILLINOIS...HOWEVER WITH DRY ATMOSPHERE FIRMLY IN PLACE...THINK THIS MAY BE A BIT OVERDONE. MEANWHILE...A WAVE TRACKING ACROSS SOUTHERN CANADA WILL PUSH A COLD FRONT SOUTHWARD INTO THE GREAT LAKES. CENTRAL ILLINOIS WILL REMAIN BETWEEN THESE TWO SYSTEMS...WITH THE END RESULT BEING A CONTINUATION OF MOSTLY SUNNY AND WARM CONDITIONS WITH AFTERNOON HIGHS AROUND 80 DEGREES FOR BOTH FRIDAY AND SATURDAY. LONG TERM...SUNDAY THROUGH WEDNESDAY ONCE UPPER LOW WEAKENS AND MOVES AWAY...RIDGE WILL BEGIN TO BUILD IN EARNEST ACROSS THE MIDWEST EARLY NEXT WEEK. RIDGE WILL BE FURTHER AMPLIFIED AS A RESULT OF NORTHERN STREAM TROUGH DIGGING INTO THE NORTHERN ROCKIES. MODELS CONTINUE TO KEEP CENTRAL ILLINOIS DRY THROUGH AT LEAST THE MIDDLE OF THE WEEK...AND LIKELY ALL THE WAY THROUGH NEXT WEEKEND. HAVE THEREFORE MADE VERY FEW CHANGES TO THE EXTENDED AT THIS TIME. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 858 PM CDT FRI SEP 19 2008 .DISCUSSION... LITTLE CHANGES FOR EVENING UPDATE. 01Z SFC ANLYS PLACES FRONT ACROSS SERN SD INTO CENTRAL MN WITH SOME WEAK THETA-E POOLING ALONG BOUNDARY. THIS IS PRODUCING 1000-1500 J/KG MLCAPES BUT WITH CINH INCREASING SO SFC BASED POTENTIAL NIL. CONVECTION SEEMS TO BE WANING AND 21Z RUC DOES NOT SHOW MUCH POTENTIAL FOR REDEVELOPMENT. ALTHOUGH THERE IS SOME ELEVATED INSTABILITY...CIN LOOKS SUFFICIENT TO SUPPRESS ANYTHING NEW. 300/305K ISENT LEVELS SHOW HIGH PRES DEFICITS AND ONLY PATCHY CONVERGENCE. CONFIDENCE NOT HIGH ENOUGH TO REMOVE CURRENT SLIGHT WORDING...BUT WOULD NOT ADD IT IN IF IT WAS NOT ALREADY THERE. && .PREV DISCUSSION... SFC MAP THIS MORNING CONTINUES TO SHOW DEVELOPING AREA OF LOW PRESSURE OVER THE CENTRAL AND WESTERN PLAINS. SFC HIGH ANCHORED OVER THE GREAT LAKES WITH PERSISTENT RIDGING ALOFT. H850 SHOWS THIN RIBBON OF MOISTURE RETURN ACROSS NEBRASKA TO THE DAKOTAS WITH MOISTURE POOL EXTENDING ACROSS THE SOUTHEAST STATES. WINDS ALOFT HAVE INCREASED WITH NICE SSW RETURN FLOW OVER IA TODAY...30 TO 35 KTS. TROF/WEAK BOUNDARY WEST EXPECTED TO MOVE EAST WITH TIME AS LOW TRACKS OVER NORTHERN MN AND THE TRAILING BOUNDARY SHEARS AND WEAKENS NEAR THE IA/MN BORDER BY LATE SAT/EARLY SUN. WITH MINOR CONVERGENCE ALONG THE BOUNDARY AND INCREASING MOISTURE RETURN...SOME HINT AT POSSIBLE ISO THUNDER FAR NORTH LATE SAT AFTERNOON. MODELS SHOWING LOW-MOD CAPE VALUES AT 600 J/KG. OTHER SLIGHT COMPLICATION IN THE WEEKEND FORECAST IS THE H500 WAVE TRACKING EAST AND THEN NORTH INTO THE MID MISSISSIPPI RIVER VALLEY TODAY. ASSOCIATED VORTICITY FIELD WEAKENS BY SAT BUT MAY BE ENOUGH LEFT OVER SAT AFTERNOON TO SPARK A FEW ISO/SCT STORMS OVER THE SOUTHEAST DURING THE DAYTIME HOURS. IN FACT...DUE TO THE LACK OF ANY STRONG DYNAMICS UNTIL MONDAY...WE CONTINUE TO SEE MAINLY LATE SUMMER DIURNAL THERMAL FORCING ENHANCING CLOUDS AND PSBL THUNDER. QUESTIONS REMAIN AS TO THE TIMING OF SYSTEM THE EARLY TO MID WEEK SYSTEM WITH THE EXPANSIVE RIDGE CURRENTLY IN PLACE TO OUR EAST. GEM/00Z EURO/UKMET SHOW GENERALLY SLOWER EAST MOVEMENT IN NEXT TUES SYSTEM THAT DEVELOPS ACROSS THE CENTRAL/WESTERN PLAINS...ALSO DRIVING THE WAVE MORE NORTH THAN EAST. GFS TRENDING TOWARD ITS FASTER EASTERLY BIAS...PROMOTING SHOWER/ THUNDER DEVELOPMENT MUCH FASTER OVER THE FORECAST AREA TUES. HAVE DECIDED TO LEAN TOWARD THE SLOWER FAMILY OF SOLNS FOR NOW...BUT EXTENDED CHANCE POPS A BIT FARTHER EAST 12Z-18Z MONDAY WITH ACTIVITY WANING INTO THE PM HOURS AS MIXING TAKES OVER. WITH GREATER CONFIDENCE IN THE SLOWER SOLNS FOR TUES/WED OF NEXT WEEK HAVE LEFT LOWER POPS OVER THE AREA TUES...INCREASING POPS TUES NIGHT NORTHWEST AND OVERSPREADING AREA WED...AS PER PREVIOUS PACKAGE AND REST OF EXTENDED THROUGH THURSDAY...LOOKING MORE LIKE THE FRONT WILL STALL AND THEN WEAKEN WITH TIME WITH CHANCES SHOWERS/STORMS POSSIBLE THROUGH THURSDAY AND HINT AT DRYING BY FRIDAY. NEWEST 12Z EURO SHOWS FRONT HAVING THE SAME CHALLENGES MOVING EAST WITH SOME WASHOUT OF THE FRONT TOWARD LATE NEXT WEEK. CHANCES FOR SEVERE STORMS OVER THE NEXT SEVEN DAYS LOOK LIMITED GIVEN THE MODEST LEVELS OF CONCURRENT WIND FIELDS AND INSTABILITY. && .AVIATION...20/00Z SEVERAL CONCERNS FOR TAFS BUT NOTHING SIGNIFICANT. HAVE REMOVED ANY MENTION OF PRECIP OR CONVECTION AT KMCW OVERNIGHT AS POTENTIAL CONTINUES TO DIMINISH AND WHAT THERE IS REMAINS NORTH. RELATIVELY HIGH MOISTURE VALUES MAY RESULT IN SOME PATCHY MVFR RADITATION FOG EARLY THIS MORNING AT SOME SITES AS CROSSOVER TEMPS ARE APPROACHED. THERE IS SOME POTENTIAL TO GO IFR...BUT NOT ENOUGH TO MENTION. HAVE ALSO ADDED CB WORDING TO KOTM SATURDAY AFTERNOON. FEEL THERE WILL BE ISOLATED SHOWERS AND THUNDERSTORMS IN SERN IA...BUT CONFIDENCE IN ANY PARTICULAR LOCATION NOT THERE TO ADD TO TERMINAL AS OF YET. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ KAJ/REV/BSS ia AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 800 PM EDT FRI SEP 19 2008 .UPDATE... A THIN LINE OF SHRA/TSRA HAVE DVLPD ALG COLD FNT OVER THE MN ARROWHEAD...SO ADDED LO CHC POPS TO THE WRN CWA THRU 06Z...WHEN THIS FNT IS EXPECTED TO PASS. ALTHOUGH LOSS OF SFC HTG MAY CAUSE THIS CNVCTN TO WEAKEN...STEEP LAPSE RATES UP TO 7.5C/KM IN THE H7-5 LYR SHOULD ALLOW THE SHRA TO LINGER IN THE PRESENCE OF SOME H85-5 QVECTOR CNVGC AND LLVL CNVGC ASSOCIATED WITH THE COLD FNT. && .SYNOPSIS... 19Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER THE WESTERN U.S. AND TROUGHING DROPPING DOWN THROUGH CENTRAL CANADA. AHEAD OF THIS TROUGH...A SHRTWV STRETCHES FROM NE ONTARIO SW TO NW WI...WHICH IS COMBINING WITH MID-LEVEL FRONTOGENESIS AND 7-7.5C/KM LAPSE RATES IN PRODUCING ISOLATED SHOWERS AND THUNDERSTORMS ON LAKE SUPERIOR INTO THE KEWEENAW. AHEAD OF THE TROUGH...WARM AIR HAS MOVED INTO UPPER MI FROM THE PLAINS...WITH A 15Z SOUNDING FROM SAW SHOWING 850MB TEMPS OF 16C. TEMPERATURES HAVE NOT MIXED UP TO THIS LEVEL...DESPITE A BREEZY SOUTHWEST WIND...DUE TO THE LOWER SUN ANGLE AROUND THE AUTUMNAL EQUINOX. NEVERTHELESS... READINGS HAVE CLIMBED ABOVE NORMAL WITH DOWNSLOPE AREAS AROUND 80...WHILE LOCATIONS DOWNWIND OF THE COOLER LAKE MI WATERS ARE IN THE MID 60S. TO THE NW...COOLER AIR CAN BE SINKING SOUTHWARD THROUGH MANITOBA...BEHIND A STRONG COLD FRONT. TEMPERATURES ARE FALLING INTO THE 40S OVER CENTRAL MANITOBA...COMPARED TO 70 DEGREE READINGS AHEAD OF THE FRONT. 850MB TEMPS WERE 1C AT CYQD AT -4C AT CHURCHILL MB...INDICATIVE ALSO OF THE COLD AIR. SOME CELLULAR LOW CLOUDS ARE ASSOCIATED WITH THE COLD AIR...BUT VERY FEW REPORTS OF ANY PCPN. FARTHER TO THE NW...HIGH PRESSURE IS LOCATED OVER FAR NORTHERN SASKATCHEWAN. && .SHORT TERM (TONIGHT AND SATURDAY)... UPPER LEVEL TROUGH OVER CENTRAL CANADA WILL DIG A BIT MORE TOWARDS UPPER MI DURING THE NEXT 18 HOURS...BUT THEN START MOVING EASTWARD DUE TO UPPER TROUGH JUST OFF THE WEST COAST TRYING TO PUSH EAST. THE DIGGING WILL BE ENOUGH TO DRIVE THE COLD FRONT SOUTH ACROSS THE CWA...THOUGH...CROSSING UPPER MI TONIGHT AND REACHING THE MILWAUKEE AREA BY 00Z SUN. UNTIL THE COLD FRONT ARRIVES (OR THE TROUGH DIGS ENOUGH SOUTH)...THE AREA WILL BE UNDER WEAK MID-LEVEL FRONTOGENESIS AND 7-7.5C/KM LAPSE RATES. THE GFS AND NAM SHOW LIGHT QPF GRADUALLY SINKING SE WITH TIME...WHICH SEEMS REASONABLE GIVEN THE FRONTOGENESIS. ADJUSTED THE FORECAST TO CONTINUE 20 POPS THROUGH MUCH OF THE NIGHT...PARTICULARLY IN THE CENTRAL U.P. SINCE THE UPPER FLOW DOES NOT APPEAR TO ALLOW FOR A FAST MOTION SOUTH WITH THE PCPN. AFTER THE FRONT PASSES...LOW CLOUDS SEEN OVER MANITOBA WILL MOVE INTO UPPER MICHIGAN...WITH THE GREATEST COVERAGE OVER THE NORTH CENTRAL U.P. WHERE UPSLOPE AND LAKE ENHANCEMENT IS EXPECTED. CLOUDS ARE EXPECTED TO STICK AROUND THROUGH MUCH OF THE MORNING UNTIL DRIER AIR AND ANTICYCLONIC LOW LEVEL FLOW ASSOCIATED WITH THE HIGH OVER NRN SASKATCHEWAN NOSING IN...ALONG WITH DAYTIME MIXING...HELP MIX/CLEAR THEM OUT SATURDAY AFTERNOON. DECLINED TO MENTION ANY PCPN WITH THE LOW CLOUDS GIVEN LACK OF REPORTS UPSTREAM AND THAT SOUNDINGS SUGGEST THE MOISTURE TO BE QUITE SHALLOW. BIGGEST IMPACTS FROM THE COLD FRONT MOVING ACROSS WILL BE ON TEMPS AND WINDS. LOW TEMPS TONIGHT ARE LIKELY OCCURRING TOWARD SUNRISE SINCE THEY PROBABLY WILL NOT FALL OFF MUCH UNTIL THE FRONT PASSES...DUE TO A SW BREEZE KEEPING THE BOUNDARY LAYER MIXED. GUSTY NORTH WINDS BEHIND THE FRONT SHOULD BRING TEMPS DOWN INTO THE 50S AND POSSIBLY UPPER 40S...COOLEST OVER THE HIGHER TERRAIN OF THE WEST HALF OF UPPER MI. WITH THE COOL AIR MOVING IN LATE TONIGHT...TEMPS ARE GOING TO STRUGGLE RISING TOMORROW. LATEST MET/MAV GUIDANCE ARE A FEW DEGREES COOLER THAN THE PREVIOUS FORECAST...AND GIVEN WHAT TEMPERATURES ARE DOING UPSTREAM OVER NORTHERN MANITOBA...FEEL THAT IS PROBABLY THE WAY TO GO. MUCH OF THE NORTHERN U.P. SHOULD BE STUCK IN THE 50S...THANKS TO 900MB TEMPS DROPPING TO 2-4C. THE SOUTHERN U.P. WILL BE WARMER...ESPECIALLY DOWN NEAR MNM WHERE 900MB TEMPS ARE THE WARMEST. .LONG TERM (SAT NIGHT THROUGH NEXT FRI)... FIRST ISSUE IN THE LONG TERM IS POTENTIAL FOR FREEZING TEMPS AND WIDESPREAD FROST AWAY FM THE IMMEDIATE LAKE SUPERIOR SHORE. LARGE HIGH PRESSURE SETTLES IN BEHIND THE COLD FRONT THAT MOVES THROUGH EARLY SATURDAY. INITIALLY DURING SATURDAY EVENING...NORTHERLY BLYR WINDS KEEP TEMPS FM FALLING TOO QUICKLY BUT EVENTUALLY WINDS MOST EVERYWHERE WILL BECOME LIGHT. LIGHT WINDS AND SKIES BECOMING CLEAR SET UP A GOOD RADIATIONAL COOLING NIGHT...ESPECIALLY AS VERY DRY AIR MOVES ACROSS IN THE FORM OF A PRECIPITABLE WATER MINIMUM. COOP GUIDANCE CONTINUES TO INDICATE MINS IN FAVORED COLD SPOTS FALLING BLO 32F AND HAVE WENT THIS WAY WITH THE LATEST MIN TEMP GRIDS. INCREASED FROST COVERAGE AS WELL...WITH WIDESPREAD FROST EXPECTED OVR MUCH OF THE CWA...AWAY FM THE LAKE SUPERIOR SHORE. THOUGHT ABOUT GOING WITH MINS BLO GUIDANCE ALONG LK MICHIGAN SHORE TOO AS KESC CAN FALL OFF MORE THAN GUIDANCE SHOWS IN THESE TYPE OF SETUPS...BUT SINCE EAST WINDS FLOWING OFF LK MICHIGAN LATE MAY PROMOTE SOME LAKE EFFECT CLOUDS (DELTA T/S APPROACH 10C WITH LK MI WATER TEMPS NEAR 17C) KEPT SHORELINE IN THE UPR 30S-LWR 40S. ONLY HEADLINE POSTED ATTM WAS A FREEZE WATCH FOR INTERIOR WEST CWA...SOUTHERN HOUGHTON TO BARAGA AND ALSO IRON. FROST ADVY LIKELY WILL BE NEEDED FOR MUCH OF THE CWA BUT WILL LEAVE THAT TO LATER SHIFTS AS IT IS STILL IN THE LONG TERM. NEXT ISSUE IS THE PERSISTENT QPF GFS SHOWS ALONG TIGHTENING H85 FRONT FOR SUN/SUN NIGHT. SIMILAR TO PAST MODEL RUNS...GFS REMAINS LARGELY ON ITS OWN AND WILL CONTINUE TO DISCOUNT. APPEARS THAT QPF IS TIED TO STEEPENING H85-H7/H7-H5 LAPSE RATES AOA 7.0C/KM AS A RESULT OF WARM ADVECTION AT H7. THERE IS ALSO SOME WEAK MID LEVEL FGEN PRESENT ALONG H85 FRONT AS WELL. WARM FRONT...FIRST AT H85 THEN AT THE SFC...LIFT THROUGH CWA SUNDAY NIGHT. AS IT LOOKED YDY...BEST H85 MOISTURE TRANSPORT AND ALSO THE STEEPER POCKET OF LAPSE RATES TEAM UP TO THE NW OF UPR LAKES INTO MANITOBA AND ONTARIO. SOUNDINGS SHOW A MID CLOUD DECK STREAMING ACROSS THE CWA LATE SUN INTO SUN NIGHT. DRY LOW LEVELS BLO THIS CLOUD BASE SHOULD PROHIBIT MUCH IN THE WAY OF PCPN AND THUS KEPT THE FORECAST DRY OVER CWA. THE COOLER TEMPERATURES AND UPPER LEVEL TROUGH FM THIS WEEKEND IS THEN REPLACED BY A WARMING TREND EARLY THIS WEEK AS UPPER RIDGE OVER THE SOUTHWEST CONUS BUILDS INTO GREAT LAKES PUSHING THE WARM FRONT NORTH OF THE REGION. WESTERN CONUS TROUGH UPSTREAM OF THE RIDGE SHIFTS EAST BY MIDWEEK BRINGING THE RETURN OF A COLD FRONT AND A CHANCE OF SHOWERS AND THUNDERSTORMS INTO THE WESTERN GREAT LAKES. EXTENDED MODELS USED...GFS/ECMWF/UKMET/CANADIAN GLOBAL...AND GFS ENSEMBLE AGREE IN THE LARGE SCALE PATTERN. TIMING OF THE COLD FRONT AND PCPN CHANCES INTO THE AREA REMAINS MAIN FOCUS OF THE EXTENDED. MAJORITY OF GUIDANCE...EXCEPT THE GFS ENSEMBLES...INDICATE A FROPA ON WED. SINCE THE GFS AND ECMWF NOW ARE IN AGREEMENT WITH THAT IDEA PLACED HIGHEST POPS IN THE GRIDS AT THAT TIME. INCREASING MOISTURE ADVECTION AT H85 AHEAD OF THE FRONT COULD EVEN TRIGGER SCATTERED SHOWERS OUT OF A MID CLOUD DECK AS EARLY AS TUESDAY. BUT SINCE GREATEST GRADIENT IN THIS ADVANCING MOISTURE STAYS OVR WESTERN LK SUPERIOR...KEPT ANY POPS TUE OUT OF THE LAND PORTION OF THE WESTERN CWA UNTIL LATE TUE NIGHT. THESE MID CLOUDS ON TUE COULD AFFECT MAX TEMPS. MIXING TO H85 TEMPS IN MID TEENS RESULTS IN MAX TEMPS INTO THE LWR 80S BUT DUE TO POSSIBLE CLOUDS...TEMPERED THIS BACK TO THE MID-UPR 70S WHICH IS STILL A NUDGE ABOVE MOST GUIDANCE. FRONT CLEARS MOST OF CWA BY LATER THU BUT THEN STALLS OUT JUST TO THE SOUTH OVR WI AND LWR MI AS THE BOUNDARY BECOMES PARALLEL TO THE UPPER FLOW. DOES NOT SEEM THAT BOUNDARY IS FAR ENOUGH AWAY TO DROP POPS IN ITS WAKE. IN FACT...LATEST GFS/ECMWF NOW INDICATE A H85-H7 WAVE RIDES ALONG THIS SFC BOUNDARY TO BRING A WIDESPREAD RAIN TO UPR LAKES THU. MOST PCPN WOULD BE OUT OF THE CWA ON FRIDAY...BUT THE APPROACH OF A MORE NORTHERN STREAM ORIGIN WAVE MAY BRING ANOTHER CHANCE FOR RAIN LATE IN THE DAY. JUST INCLUDED SOME POPS OVR WRN LK SUPERIOR AT THIS POINT. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... ALTHOUGH STRONG WSW WINDS WL LINGER JUST ABV THE SFC THIS EVNG... LOSS OF DIURNAL HTG WL LIMIT MIXING OF THIS MOMENTUM TO THE SFC AND RESULT IN LLWS AT BOTH SITES. OTRW...THE LLVLS WL BE TOO DRY PER RECENT TAMDAR SDNGS FOR ANYTHING BUT VFR CONDITIONS THIS EVNG. EXPECT A SHARP WSHFT TO NNE FOLLOWING COLD FROPA LATE TNGT. THERE MAY BE A -SHRA AT CMX WITH THE APRCH OF THIS FNT CLOSER TO MORE IMPRESSIVE DYNAMIC FORCING IN ONTARIO. AIRMASS UPSTREAM IS NOT PARTICULARLY MOIST...SO EXPECT A BKN SC DECK/MVFR CONDITIONS TO IMPACT ONLY SAW WHERE EXPECTED POST FROPA WIND WL UPSLOPE AS MUCH COOLER AIR ARRIVES ON THE HEELS OF GUSTY WINDS. DIURNAL HTG WL SCT OUT THIS MVFR DECK AT SAW SAT AFTN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... SW WINDS OF 15 TO 30 KT...GREATEST OVER NORTH CENTRAL AND FAR EASTERN LAKE SUPERIOR...WILL DIMINISH BRIEFLY THIS EVENING...THEN RAPIDLY INCREASE OUT OF THE N OR NE TO 20 TO 30 KT AFTER MIDNIGHT IN THE WAKE OF A COLD FRONT DROPPING SOUTH ACROSS LAKE SUPERIOR. TOUGH CALL ON WHETHER OR NOT WINDS WILL REACH GALE FORCE ON NORTH CENTRAL AND EASTERN LAKE SUPERIOR LATE TONIGHT. RAPID PRESSURE RISES BEHIND THE FRONT WOULD SUGGEST IT...BUT WIND REPORTS AT EXPOSED LOCATIONS...EVEN ON LAKE WINNIPEG...HAVE BEEN GENERALLY 30 KT OR LESS. THEREFORE...HAVE NOT GONE WITH A GALE WARNING AND MENTIONED A FEW GALE FORCE GUSTS INSTEAD. WINDS WILL NEED TO BE MONITORED AND A GALE WARNING COULD STILL BE ISSUED. OTHERWISE...HIGH PRESSURE OVER NRN SASKATCHEWAN NOSING SE INTO LAKE SUPERIOR ON SAT WILL HELP DIMINISH THE WINDS TO UNDER 20 KT BY SAT EVENING. LIGHT WIND REGIME PERSISTS INTO MONDAY THEN SOUTH WINDS AHEAD OF THE APPROACHING COLD FRONT INCREASE TO 30 KNOTS TUE BEFORE DIMINISHING ON WED. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... FREEZE WATCH LATE SATURDAY NIGHT THROUGH EARLY SUNDAY MORNING MIZ004-010-084. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ UPDATE...KC SYNOPSIS/SHORT TERM..AJ LONG TERM...JLA AVIATION...KC MARINE...AJ/JLA mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 730 PM EDT FRI SEP 19 2008 UPDATED FOR 00Z TAF ISSUANCE .SYNOPSIS... 19Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER THE WESTERN U.S. AND TROUGHING DROPPING DOWN THROUGH CENTRAL CANADA. AHEAD OF THIS TROUGH...A SHRTWV STRETCHES FROM NE ONTARIO SW TO NW WI...WHICH IS COMBINING WITH MID-LEVEL FRONTOGENESIS AND 7-7.5C/KM LAPSE RATES IN PRODUCING ISOLATED SHOWERS AND THUNDERSTORMS ON LAKE SUPERIOR INTO THE KEWEENAW. AHEAD OF THE TROUGH...WARM AIR HAS MOVED INTO UPPER MI FROM THE PLAINS...WITH A 15Z SOUNDING FROM SAW SHOWING 850MB TEMPS OF 16C. TEMPERATURES HAVE NOT MIXED UP TO THIS LEVEL...DESPITE A BREEZY SOUTHWEST WIND...DUE TO THE LOWER SUN ANGLE AROUND THE AUTUMNAL EQUINOX. NEVERTHELESS... READINGS HAVE CLIMBED ABOVE NORMAL WITH DOWNSLOPE AREAS AROUND 80...WHILE LOCATIONS DOWNWIND OF THE COOLER LAKE MI WATERS ARE IN THE MID 60S. TO THE NW...COOLER AIR CAN BE SINKING SOUTHWARD THROUGH MANITOBA...BEHIND A STRONG COLD FRONT. TEMPERATURES ARE FALLING INTO THE 40S OVER CENTRAL MANITOBA...COMPARED TO 70 DEGREE READINGS AHEAD OF THE FRONT. 850MB TEMPS WERE 1C AT CYQD AT -4C AT CHURCHILL MB...INDICATIVE ALSO OF THE COLD AIR. SOME CELLULAR LOW CLOUDS ARE ASSOCIATED WITH THE COLD AIR...BUT VERY FEW REPORTS OF ANY PCPN. FARTHER TO THE NW...HIGH PRESSURE IS LOCATED OVER FAR NORTHERN SASKATCHEWAN. && .SHORT TERM (TONIGHT AND SATURDAY)... UPPER LEVEL TROUGH OVER CENTRAL CANADA WILL DIG A BIT MORE TOWARDS UPPER MI DURING THE NEXT 18 HOURS...BUT THEN START MOVING EASTWARD DUE TO UPPER TROUGH JUST OFF THE WEST COAST TRYING TO PUSH EAST. THE DIGGING WILL BE ENOUGH TO DRIVE THE COLD FRONT SOUTH ACROSS THE CWA...THOUGH...CROSSING UPPER MI TONIGHT AND REACHING THE MILWAUKEE AREA BY 00Z SUN. UNTIL THE COLD FRONT ARRIVES (OR THE TROUGH DIGS ENOUGH SOUTH)...THE AREA WILL BE UNDER WEAK MID-LEVEL FRONTOGENESIS AND 7-7.5C/KM LAPSE RATES. THE GFS AND NAM SHOW LIGHT QPF GRADUALLY SINKING SE WITH TIME...WHICH SEEMS REASONABLE GIVEN THE FRONTOGENESIS. ADJUSTED THE FORECAST TO CONTINUE 20 POPS THROUGH MUCH OF THE NIGHT...PARTICULARLY IN THE CENTRAL U.P. SINCE THE UPPER FLOW DOES NOT APPEAR TO ALLOW FOR A FAST MOTION SOUTH WITH THE PCPN. AFTER THE FRONT PASSES...LOW CLOUDS SEEN OVER MANITOBA WILL MOVE INTO UPPER MICHIGAN...WITH THE GREATEST COVERAGE OVER THE NORTH CENTRAL U.P. WHERE UPSLOPE AND LAKE ENHANCEMENT IS EXPECTED. CLOUDS ARE EXPECTED TO STICK AROUND THROUGH MUCH OF THE MORNING UNTIL DRIER AIR AND ANTICYCLONIC LOW LEVEL FLOW ASSOCIATED WITH THE HIGH OVER NRN SASKATCHEWAN NOSING IN...ALONG WITH DAYTIME MIXING...HELP MIX/CLEAR THEM OUT SATURDAY AFTERNOON. DECLINED TO MENTION ANY PCPN WITH THE LOW CLOUDS GIVEN LACK OF REPORTS UPSTREAM AND THAT SOUNDINGS SUGGEST THE MOISTURE TO BE QUITE SHALLOW. BIGGEST IMPACTS FROM THE COLD FRONT MOVING ACROSS WILL BE ON TEMPS AND WINDS. LOW TEMPS TONIGHT ARE LIKELY OCCURRING TOWARD SUNRISE SINCE THEY PROBABLY WILL NOT FALL OFF MUCH UNTIL THE FRONT PASSES...DUE TO A SW BREEZE KEEPING THE BOUNDARY LAYER MIXED. GUSTY NORTH WINDS BEHIND THE FRONT SHOULD BRING TEMPS DOWN INTO THE 50S AND POSSIBLY UPPER 40S...COOLEST OVER THE HIGHER TERRAIN OF THE WEST HALF OF UPPER MI. WITH THE COOL AIR MOVING IN LATE TONIGHT...TEMPS ARE GOING TO STRUGGLE RISING TOMORROW. LATEST MET/MAV GUIDANCE ARE A FEW DEGREES COOLER THAN THE PREVIOUS FORECAST...AND GIVEN WHAT TEMPERATURES ARE DOING UPSTREAM OVER NORTHERN MANITOBA...FEEL THAT IS PROBABLY THE WAY TO GO. MUCH OF THE NORTHERN U.P. SHOULD BE STUCK IN THE 50S...THANKS TO 900MB TEMPS DROPPING TO 2-4C. THE SOUTHERN U.P. WILL BE WARMER...ESPECIALLY DOWN NEAR MNM WHERE 900MB TEMPS ARE THE WARMEST. .LONG TERM (SAT NIGHT THROUGH NEXT FRI)... FIRST ISSUE IN THE LONG TERM IS POTENTIAL FOR FREEZING TEMPS AND WIDESPREAD FROST AWAY FM THE IMMEDIATE LAKE SUPERIOR SHORE. LARGE HIGH PRESSURE SETTLES IN BEHIND THE COLD FRONT THAT MOVES THROUGH EARLY SATURDAY. INITIALLY DURING SATURDAY EVENING...NORTHERLY BLYR WINDS KEEP TEMPS FM FALLING TOO QUICKLY BUT EVENTUALLY WINDS MOST EVERYWHERE WILL BECOME LIGHT. LIGHT WINDS AND SKIES BECOMING CLEAR SET UP A GOOD RADIATIONAL COOLING NIGHT...ESPECIALLY AS VERY DRY AIR MOVES ACROSS IN THE FORM OF A PRECIPITABLE WATER MINIMUM. COOP GUIDANCE CONTINUES TO INDICATE MINS IN FAVORED COLD SPOTS FALLING BLO 32F AND HAVE WENT THIS WAY WITH THE LATEST MIN TEMP GRIDS. INCREASED FROST COVERAGE AS WELL...WITH WIDESPREAD FROST EXPECTED OVR MUCH OF THE CWA...AWAY FM THE LAKE SUPERIOR SHORE. THOUGHT ABOUT GOING WITH MINS BLO GUIDANCE ALONG LK MICHIGAN SHORE TOO AS KESC CAN FALL OFF MORE THAN GUIDANCE SHOWS IN THESE TYPE OF SETUPS...BUT SINCE EAST WINDS FLOWING OFF LK MICHIGAN LATE MAY PROMOTE SOME LAKE EFFECT CLOUDS (DELTA T/S APPROACH 10C WITH LK MI WATER TEMPS NEAR 17C) KEPT SHORELINE IN THE UPR 30S-LWR 40S. ONLY HEADLINE POSTED ATTM WAS A FREEZE WATCH FOR INTERIOR WEST CWA...SOUTHERN HOUGHTON TO BARAGA AND ALSO IRON. FROST ADVY LIKELY WILL BE NEEDED FOR MUCH OF THE CWA BUT WILL LEAVE THAT TO LATER SHIFTS AS IT IS STILL IN THE LONG TERM. NEXT ISSUE IS THE PERSISTENT QPF GFS SHOWS ALONG TIGHTENING H85 FRONT FOR SUN/SUN NIGHT. SIMILAR TO PAST MODEL RUNS...GFS REMAINS LARGELY ON ITS OWN AND WILL CONTINUE TO DISCOUNT. APPEARS THAT QPF IS TIED TO STEEPENING H85-H7/H7-H5 LAPSE RATES AOA 7.0C/KM AS A RESULT OF WARM ADVECTION AT H7. THERE IS ALSO SOME WEAK MID LEVEL FGEN PRESENT ALONG H85 FRONT AS WELL. WARM FRONT...FIRST AT H85 THEN AT THE SFC...LIFT THROUGH CWA SUNDAY NIGHT. AS IT LOOKED YDY...BEST H85 MOISTURE TRANSPORT AND ALSO THE STEEPER POCKET OF LAPSE RATES TEAM UP TO THE NW OF UPR LAKES INTO MANITOBA AND ONTARIO. SOUNDINGS SHOW A MID CLOUD DECK STREAMING ACROSS THE CWA LATE SUN INTO SUN NIGHT. DRY LOW LEVELS BLO THIS CLOUD BASE SHOULD PROHIBIT MUCH IN THE WAY OF PCPN AND THUS KEPT THE FORECAST DRY OVER CWA. THE COOLER TEMPERATURES AND UPPER LEVEL TROUGH FM THIS WEEKEND IS THEN REPLACED BY A WARMING TREND EARLY THIS WEEK AS UPPER RIDGE OVER THE SOUTHWEST CONUS BUILDS INTO GREAT LAKES PUSHING THE WARM FRONT NORTH OF THE REGION. WESTERN CONUS TROUGH UPSTREAM OF THE RIDGE SHIFTS EAST BY MIDWEEK BRINGING THE RETURN OF A COLD FRONT AND A CHANCE OF SHOWERS AND THUNDERSTORMS INTO THE WESTERN GREAT LAKES. EXTENDED MODELS USED...GFS/ECMWF/UKMET/CANADIAN GLOBAL...AND GFS ENSEMBLE AGREE IN THE LARGE SCALE PATTERN. TIMING OF THE COLD FRONT AND PCPN CHANCES INTO THE AREA REMAINS MAIN FOCUS OF THE EXTENDED. MAJORITY OF GUIDANCE...EXCEPT THE GFS ENSEMBLES...INDICATE A FROPA ON WED. SINCE THE GFS AND ECMWF NOW ARE IN AGREEMENT WITH THAT IDEA PLACED HIGHEST POPS IN THE GRIDS AT THAT TIME. INCREASING MOISTURE ADVECTION AT H85 AHEAD OF THE FRONT COULD EVEN TRIGGER SCATTERED SHOWERS OUT OF A MID CLOUD DECK AS EARLY AS TUESDAY. BUT SINCE GREATEST GRADIENT IN THIS ADVANCING MOISTURE STAYS OVR WESTERN LK SUPERIOR...KEPT ANY POPS TUE OUT OF THE LAND PORTION OF THE WESTERN CWA UNTIL LATE TUE NIGHT. THESE MID CLOUDS ON TUE COULD AFFECT MAX TEMPS. MIXING TO H85 TEMPS IN MID TEENS RESULTS IN MAX TEMPS INTO THE LWR 80S BUT DUE TO POSSIBLE CLOUDS...TEMPERED THIS BACK TO THE MID-UPR 70S WHICH IS STILL A NUDGE ABOVE MOST GUIDANCE. FRONT CLEARS MOST OF CWA BY LATER THU BUT THEN STALLS OUT JUST TO THE SOUTH OVR WI AND LWR MI AS THE BOUNDARY BECOMES PARALLEL TO THE UPPER FLOW. DOES NOT SEEM THAT BOUNDARY IS FAR ENOUGH AWAY TO DROP POPS IN ITS WAKE. IN FACT...LATEST GFS/ECMWF NOW INDICATE A H85-H7 WAVE RIDES ALONG THIS SFC BOUNDARY TO BRING A WIDESPREAD RAIN TO UPR LAKES THU. MOST PCPN WOULD BE OUT OF THE CWA ON FRIDAY...BUT THE APPROACH OF A MORE NORTHERN STREAM ORIGIN WAVE MAY BRING ANOTHER CHANCE FOR RAIN LATE IN THE DAY. JUST INCLUDED SOME POPS OVR WRN LK SUPERIOR AT THIS POINT. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... ALTHOUGH STRONG WSW WINDS WL LINGER JUST ABV THE SFC THIS EVNG... LOSS OF DIURNAL HTG WL LIMIT MIXING OF THIS MOMENTUM TO THE SFC AND RESULT IN LLWS AT BOTH SITES. OTRW...THE LLVLS WL BE TOO DRY PER RECENT TAMDAR SDNGS FOR ANYTHING BUT VFR CONDITIONS THIS EVNG. EXPECT A SHARP WSHFT TO NNE FOLLOWING COLD FROPA LATE TNGT. THERE MAY BE A -SHRA AT CMX WITH THE APRCH OF THIS FNT CLOSER TO MORE IMPRESSIVE DYNAMIC FORCING IN ONTARIO. AIRMASS UPSTREAM IS NOT PARTICULARLY MOIST...SO EXPECT A BKN SC DECK/MVFR CONDITIONS TO IMPACT ONLY SAW WHERE EXPECTED POST FROPA WIND WL UPSLOPE AS MUCH COOLER AIR ARRIVES ON THE HEELS OF GUSTY WINDS. DIURNAL HTG WL SCT OUT THIS MVFR DECK AT SAW SAT AFTN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... SW WINDS OF 15 TO 30 KT...GREATEST OVER NORTH CENTRAL AND FAR EASTERN LAKE SUPERIOR...WILL DIMINISH BRIEFLY THIS EVENING...THEN RAPIDLY INCREASE OUT OF THE N OR NE TO 20 TO 30 KT AFTER MIDNIGHT IN THE WAKE OF A COLD FRONT DROPPING SOUTH ACROSS LAKE SUPERIOR. TOUGH CALL ON WHETHER OR NOT WINDS WILL REACH GALE FORCE ON NORTH CENTRAL AND EASTERN LAKE SUPERIOR LATE TONIGHT. RAPID PRESSURE RISES BEHIND THE FRONT WOULD SUGGEST IT...BUT WIND REPORTS AT EXPOSED LOCATIONS...EVEN ON LAKE WINNIPEG...HAVE BEEN GENERALLY 30 KT OR LESS. THEREFORE...HAVE NOT GONE WITH A GALE WARNING AND MENTIONED A FEW GALE FORCE GUSTS INSTEAD. WINDS WILL NEED TO BE MONITORED AND A GALE WARNING COULD STILL BE ISSUED. OTHERWISE...HIGH PRESSURE OVER NRN SASKATCHEWAN NOSING SE INTO LAKE SUPERIOR ON SAT WILL HELP DIMINISH THE WINDS TO UNDER 20 KT BY SAT EVENING. LIGHT WIND REGIME PERSISTS INTO MONDAY THEN SOUTH WINDS AHEAD OF THE APPROACHING COLD FRONT INCREASE TO 30 KNOTS TUE BEFORE DIMINISHING ON WED. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... FREEZE WATCH LATE SATURDAY NIGHT THROUGH EARLY SUNDAY MORNING MIZ004-010-084. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/SHORT TERM..AJ LONG TERM...JLA AVIATION...KC MARINE...AJ/JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 400 PM EDT FRI SEP 19 2008 .SYNOPSIS... 19Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER THE WESTERN U.S. AND TROUGHING DROPPING DOWN THROUGH CENTRAL CANADA. AHEAD OF THIS TROUGH...A SHRTWV STRETCHES FROM NE ONTARIO SW TO NW WI...WHICH IS COMBINING WITH MID-LEVEL FRONTOGENESIS AND 7-7.5C/KM LAPSE RATES IN PRODUCING ISOLATED SHOWERS AND THUNDERSTORMS ON LAKE SUPERIOR INTO THE KEWEENAW. AHEAD OF THE TROUGH...WARM AIR HAS MOVED INTO UPPER MI FROM THE PLAINS...WITH A 15Z SOUNDING FROM SAW SHOWING 850MB TEMPS OF 16C. TEMPERATURES HAVE NOT MIXED UP TO THIS LEVEL...DESPITE A BREEZY SOUTHWEST WIND...DUE TO THE LOWER SUN ANGLE AROUND THE AUTUMNAL EQUINOX. NEVERTHELESS... READINGS HAVE CLIMBED ABOVE NORMAL WITH DOWNSLOPE AREAS AROUND 80...WHILE LOCATIONS DOWNWIND OF THE COOLER LAKE MI WATERS ARE IN THE MID 60S. TO THE NW...COOLER AIR CAN BE SINKING SOUTHWARD THROUGH MANITOBA...BEHIND A STRONG COLD FRONT. TEMPERATURES ARE FALLING INTO THE 40S OVER CENTRAL MANITOBA...COMPARED TO 70 DEGREE READINGS AHEAD OF THE FRONT. 850MB TEMPS WERE 1C AT CYQD AT -4C AT CHURCHILL MB...INDICATIVE ALSO OF THE COLD AIR. SOME CELLULAR LOW CLOUDS ARE ASSOCIATED WITH THE COLD AIR...BUT VERY FEW REPORTS OF ANY PCPN. FARTHER TO THE NW...HIGH PRESSURE IS LOCATED OVER FAR NORTHERN SASKATCHEWAN. && .SHORT TERM (TONIGHT AND SATURDAY)... UPPER LEVEL TROUGH OVER CENTRAL CANADA WILL DIG A BIT MORE TOWARDS UPPER MI DURING THE NEXT 18 HOURS...BUT THEN START MOVING EASTWARD DUE TO UPPER TROUGH JUST OFF THE WEST COAST TRYING TO PUSH EAST. THE DIGGING WILL BE ENOUGH TO DRIVE THE COLD FRONT SOUTH ACROSS THE CWA...THOUGH...CROSSING UPPER MI TONIGHT AND REACHING THE MILWAUKEE AREA BY 00Z SUN. UNTIL THE COLD FRONT ARRIVES (OR THE TROUGH DIGS ENOUGH SOUTH)...THE AREA WILL BE UNDER WEAK MID-LEVEL FRONTOGENESIS AND 7-7.5C/KM LAPSE RATES. THE GFS AND NAM SHOW LIGHT QPF GRADUALLY SINKING SE WITH TIME...WHICH SEEMS REASONABLE GIVEN THE FRONTOGENESIS. ADJUSTED THE FORECAST TO CONTINUE 20 POPS THROUGH MUCH OF THE NIGHT...PARTICULARLY IN THE CENTRAL U.P. SINCE THE UPPER FLOW DOES NOT APPEAR TO ALLOW FOR A FAST MOTION SOUTH WITH THE PCPN. AFTER THE FRONT PASSES...LOW CLOUDS SEEN OVER MANITOBA WILL MOVE INTO UPPER MICHIGAN...WITH THE GREATEST COVERAGE OVER THE NORTH CENTRAL U.P. WHERE UPSLOPE AND LAKE ENHANCEMENT IS EXPECTED. CLOUDS ARE EXPECTED TO STICK AROUND THROUGH MUCH OF THE MORNING UNTIL DRIER AIR AND ANTICYCLONIC LOW LEVEL FLOW ASSOCIATED WITH THE HIGH OVER NRN SASKATCHEWAN NOSING IN...ALONG WITH DAYTIME MIXING...HELP MIX/CLEAR THEM OUT SATURDAY AFTERNOON. DECLINED TO MENTION ANY PCPN WITH THE LOW CLOUDS GIVEN LACK OF REPORTS UPSTREAM AND THAT SOUNDINGS SUGGEST THE MOISTURE TO BE QUITE SHALLOW. BIGGEST IMPACTS FROM THE COLD FRONT MOVING ACROSS WILL BE ON TEMPS AND WINDS. LOW TEMPS TONIGHT ARE LIKELY OCCURRING TOWARD SUNRISE SINCE THEY PROBABLY WILL NOT FALL OFF MUCH UNTIL THE FRONT PASSES...DUE TO A SW BREEZE KEEPING THE BOUNDARY LAYER MIXED. GUSTY NORTH WINDS BEHIND THE FRONT SHOULD BRING TEMPS DOWN INTO THE 50S AND POSSIBLY UPPER 40S...COOLEST OVER THE HIGHER TERRAIN OF THE WEST HALF OF UPPER MI. WITH THE COOL AIR MOVING IN LATE TONIGHT...TEMPS ARE GOING TO STRUGGLE RISING TOMORROW. LATEST MET/MAV GUIDANCE ARE A FEW DEGREES COOLER THAN THE PREVIOUS FORECAST...AND GIVEN WHAT TEMPERATURES ARE DOING UPSTREAM OVER NORTHERN MANITOBA...FEEL THAT IS PROBABLY THE WAY TO GO. MUCH OF THE NORTHERN U.P. SHOULD BE STUCK IN THE 50S...THANKS TO 900MB TEMPS DROPPING TO 2-4C. THE SOUTHERN U.P. WILL BE WARMER...ESPECIALLY DOWN NEAR MNM WHERE 900MB TEMPS ARE THE WARMEST. .LONG TERM (SAT NIGHT THROUGH NEXT FRI)... FIRST ISSUE IN THE LONG TERM IS POTENTIAL FOR FREEZING TEMPS AND WIDESPREAD FROST AWAY FM THE IMMEDIATE LAKE SUPERIOR SHORE. LARGE HIGH PRESSURE SETTLES IN BEHIND THE COLD FRONT THAT MOVES THROUGH EARLY SATURDAY. INITIALLY DURING SATURDAY EVENING...NORTHERLY BLYR WINDS KEEP TEMPS FM FALLING TOO QUICKLY BUT EVENTUALLY WINDS MOST EVERYWHERE WILL BECOME LIGHT. LIGHT WINDS AND SKIES BECOMING CLEAR SET UP A GOOD RADIATIONAL COOLING NIGHT...ESPECIALLY AS VERY DRY AIR MOVES ACROSS IN THE FORM OF A PRECIPITABLE WATER MINIMUM. COOP GUIDANCE CONTINUES TO INDICATE MINS IN FAVORED COLD SPOTS FALLING BLO 32F AND HAVE WENT THIS WAY WITH THE LATEST MIN TEMP GRIDS. INCREASED FROST COVERAGE AS WELL...WITH WIDESPREAD FROST EXPECTED OVR MUCH OF THE CWA...AWAY FM THE LAKE SUPERIOR SHORE. THOUGHT ABOUT GOING WITH MINS BLO GUIDANCE ALONG LK MICHIGAN SHORE TOO AS KESC CAN FALL OFF MORE THAN GUIDANCE SHOWS IN THESE TYPE OF SETUPS...BUT SINCE EAST WINDS FLOWING OFF LK MICHIGAN LATE MAY PROMOTE SOME LAKE EFFECT CLOUDS (DELTA T/S APPROACH 10C WITH LK MI WATER TEMPS NEAR 17C) KEPT SHORELINE IN THE UPR 30S-LWR 40S. ONLY HEADLINE POSTED ATTM WAS A FREEZE WATCH FOR INTERIOR WEST CWA...SOUTHERN HOUGHTON TO BARAGA AND ALSO IRON. FROST ADVY LIKELY WILL BE NEEDED FOR MUCH OF THE CWA BUT WILL LEAVE THAT TO LATER SHIFTS AS IT IS STILL IN THE LONG TERM. NEXT ISSUE IS THE PERSISTENT QPF GFS SHOWS ALONG TIGHTENING H85 FRONT FOR SUN/SUN NIGHT. SIMILAR TO PAST MODEL RUNS...GFS REMAINS LARGELY ON ITS OWN AND WILL CONTINUE TO DISCOUNT. APPEARS THAT QPF IS TIED TO STEEPENING H85-H7/H7-H5 LAPSE RATES AOA 7.0C/KM AS A RESULT OF WARM ADVECTION AT H7. THERE IS ALSO SOME WEAK MID LEVEL FGEN PRESENT ALONG H85 FRONT AS WELL. WARM FRONT...FIRST AT H85 THEN AT THE SFC...LIFT THROUGH CWA SUNDAY NIGHT. AS IT LOOKED YDY...BEST H85 MOISTURE TRANSPORT AND ALSO THE STEEPER POCKET OF LAPSE RATES TEAM UP TO THE NW OF UPR LAKES INTO MANITOBA AND ONTARIO. SOUNDINGS SHOW A MID CLOUD DECK STREAMING ACROSS THE CWA LATE SUN INTO SUN NIGHT. DRY LOW LEVELS BLO THIS CLOUD BASE SHOULD PROHIBIT MUCH IN THE WAY OF PCPN AND THUS KEPT THE FORECAST DRY OVER CWA. THE COOLER TEMPERATURES AND UPPER LEVEL TROUGH FM THIS WEEKEND IS THEN REPLACED BY A WARMING TREND EARLY THIS WEEK AS UPPER RIDGE OVER THE SOUTHWEST CONUS BUILDS INTO GREAT LAKES PUSHING THE WARM FRONT NORTH OF THE REGION. WESTERN CONUS TROUGH UPSTREAM OF THE RIDGE SHIFTS EAST BY MIDWEEK BRINGING THE RETURN OF A COLD FRONT AND A CHANCE OF SHOWERS AND THUNDERSTORMS INTO THE WESTERN GREAT LAKES. EXTENDED MODELS USED...GFS/ECMWF/UKMET/CANADIAN GLOBAL...AND GFS ENSEMBLE AGREE IN THE LARGE SCALE PATTERN. TIMING OF THE COLD FRONT AND PCPN CHANCES INTO THE AREA REMAINS MAIN FOCUS OF THE EXTENDED. MAJORITY OF GUIDANCE...EXCEPT THE GFS ENSEMBLES...INDICATE A FROPA ON WED. SINCE THE GFS AND ECMWF NOW ARE IN AGREEMENT WITH THAT IDEA PLACED HIGHEST POPS IN THE GRIDS AT THAT TIME. INCREASING MOISTURE ADVECTION AT H85 AHEAD OF THE FRONT COULD EVEN TRIGGER SCATTERED SHOWERS OUT OF A MID CLOUD DECK AS EARLY AS TUESDAY. BUT SINCE GREATEST GRADIENT IN THIS ADVANCING MOISTURE STAYS OVR WESTERN LK SUPERIOR...KEPT ANY POPS TUE OUT OF THE LAND PORTION OF THE WESTERN CWA UNTIL LATE TUE NIGHT. THESE MID CLOUDS ON TUE COULD AFFECT MAX TEMPS. MIXING TO H85 TEMPS IN MID TEENS RESULTS IN MAX TEMPS INTO THE LWR 80S BUT DUE TO POSSIBLE CLOUDS...TEMPERED THIS BACK TO THE MID-UPR 70S WHICH IS STILL A NUDGE ABOVE MOST GUIDANCE. FRONT CLEARS MOST OF CWA BY LATER THU BUT THEN STALLS OUT JUST TO THE SOUTH OVR WI AND LWR MI AS THE BOUNDARY BECOMES PARALLEL TO THE UPPER FLOW. DOES NOT SEEM THAT BOUNDARY IS FAR ENOUGH AWAY TO DROP POPS IN ITS WAKE. IN FACT...LATEST GFS/ECMWF NOW INDICATE A H85-H7 WAVE RIDES ALONG THIS SFC BOUNDARY TO BRING A WIDESPREAD RAIN TO UPR LAKES THU. MOST PCPN WOULD BE OUT OF THE CWA ON FRIDAY...BUT THE APPROACH OF A MORE NORTHERN STREAM ORIGIN WAVE MAY BRING ANOTHER CHANCE FOR RAIN LATE IN THE DAY. JUST INCLUDED SOME POPS OVR WRN LK SUPERIOR AT THIS POINT. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... GUSTY WINDS OCCURRING AT BOTH TAF SITES DUE TO A TIGHT PRESSURE GRADIENT BETWEEN TWO COLD FRONTS DROPPING DOWN FROM CANADA AND HIGH PRESSURE OVER SE ONTARIO. IN ADDITION...WARM MOIST AIR BEING PULLED INTO THE AREA IS SUPPORTING MID LEVEL CLOUDS...WITH A FEW SHOWERS AND THUNDERSTORMS ACROSS WESTERN LAKE SUPERIOR. ONLY CONFIDENT RIGHT NOW TO INCLUDE A 3 HOUR TEMPO GROUP FOR CMX WITH A VFR CIG AND CB GROUP. ALL OF THE PCPN IS MOVING SE...AND SHOULD BE AWAY FROM CMX BY 00Z AND SAW BY 06Z. WINDS DIMINISHING THIS EVENING COMBINED WITH WINDS STAYING BREEZY JUST ABOVE THE SFC SHOULD RESULT IN SOME LLWS THROUGH 06Z. THE SECOND COLD FRONT OVER CENTRAL CANADA SHOULD DROP SOUTH ACROSS THE TAF SITES AFTER 06Z...CAUSING A RAPID WIND SHIFT AND INCREASE FROM THE NORTH...ALONG WITH SOME MVFR STRATOCUMULUS. WIND DIRECTION NOT AS FAVORABLE FOR A BKN DECK AT CMX COMPARED TO SAW...SO NO CIG MENTIONED AT CMX. WINDS SHOULD DIMINISH LATE SAT MRNG AS HIGH PRESSURE BEGINS NOSING IN BEHIND THE COLD FRONT. MVFR CLOUDS AT SAW WILL LIKELY BREAK UP JUST AFTER 18Z. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... SW WINDS OF 15 TO 30 KT...GREATEST OVER NORTH CENTRAL AND FAR EASTERN LAKE SUPERIOR...WILL DIMINISH BRIEFLY THIS EVENING...THEN RAPIDLY INCREASE OUT OF THE N OR NE TO 20 TO 30 KT AFTER MIDNIGHT IN THE WAKE OF A COLD FRONT DROPPING SOUTH ACROSS LAKE SUPERIOR. TOUGH CALL ON WHETHER OR NOT WINDS WILL REACH GALE FORCE ON NORTH CENTRAL AND EASTERN LAKE SUPERIOR LATE TONIGHT. RAPID PRESSURE RISES BEHIND THE FRONT WOULD SUGGEST IT...BUT WIND REPORTS AT EXPOSED LOCATIONS...EVEN ON LAKE WINNIPEG...HAVE BEEN GENERALLY 30 KT OR LESS. THEREFORE...HAVE NOT GONE WITH A GALE WARNING AND MENTIONED A FEW GALE FORCE GUSTS INSTEAD. WINDS WILL NEED TO BE MONITORED AND A GALE WARNING COULD STILL BE ISSUED. OTHERWISE...HIGH PRESSURE OVER NRN SASKATCHEWAN NOSING SE INTO LAKE SUPERIOR ON SAT WILL HELP DIMINISH THE WINDS TO UNDER 20 KT BY SAT EVENING. LIGHT WIND REGIME PERSISTS INTO MONDAY THEN SOUTH WINDS AHEAD OF THE APPROACHING COLD FRONT INCREASE TO 30 KNOTS TUE BEFORE DIMINISHING ON WED. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... FREEZE WATCH LATE SATURDAY NIGHT THROUGH EARLY SUNDAY MORNING MIZ004-010-084. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/SHORT TERM..AJ LONG TERM...JLA AVIATION...AJ MARINE...AJ/JLA mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 133 PM EDT FRI SEP 19 2008 UPDATED AVIATION DISCUSSION FOR 18Z TAF ISSUANCE .DISCUSSION... WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL MID/UPPER LEVEL FLOW ACROSS MOST OF THE NRN CONUS DOWNSTREAM FROM A RIDGE OVER WRN NOAM. THE MOST PROMINENT SHORTWAVE TROUGH OVER THE REGION WAS WELL TO THE NORTH OVER NRN MANITOBA WITH A WEAKER/SHEARED SHRTWV FARTHER S FROM WRN ONTARIO INTO THE CNTRL DAKOTAS. AT THE SFC...A 996 MB LOW WAS LOCATED OVER NE MANITOBA WITH A COLD FRONT THROUGH LK WINNIPEG INTO SRN SASK. A TROUGH ALSO EXTENDED FROM SE MANITOBA INTO CNTRL SD. STRONG SSW FLOW INTO UPPER MI AND LK SUPERIOR...PER KMQT VAD WIND PRFL 45 KT 2K FT WIND...WITH STRONG 925-800 MB THETA-E ADVECTION AND ASSOCIATED 300K-305K ISENTROPIC ASCENT SUPPORTED SHRA/TSRA OVER NE LAKE SUPERIOR AND SOME ISOLD LIGHT SHOWERS INTO N CNTRL UPPER MI. TODAY...EXPECT THE ISOLD SHOWERS OVER N CNTRL UPPER MI TO PROGRESS TO THE EAST BEFORE 12Z. ADDITIONAL SLIGHT CHANCE FOR SHRA/TSRA WILL BE SUPPORTED BY A BAND OF 305K-310K ISENTROPIC LIFT AHEAD OF THE TROUGH AND DAKOTAS SHRTWV. TS POTENTIAL REMAINS WITH MUCAPE VALUES IN THE 200-400 J/KG RANGE ASSOCIATED WITH STEEP 700-500 MB LAPSE RATES AROUND 7.5 C/KM. 850 MB TEMPS TO AROUND 14C AND DECENT MIXING WITH SOME SUNSHINE AND STIFF SW WINDS WILL SUPPORT MAX READINGS INTO THE UPPER 70S. TONIGHT INTO SATURDAY...AS THE NRN MANITOBA SHRTWV AND SFC LOW MOVES INTO NRN QUEBEC...A COLD FRONT WILL PLUNGE SOUTHEASTWARD THROUGH THE UPPER GREAT LAKES. A BAND OF 900-800 MB FGEN WITH THE SHARP TEMP GRADIENT COULD PRODUCE A FEW LIGHT SHOWERS TONIGHT. HOWEVER SINCE MOISTURE WILL BE LIMITED/SHALLOW ONLY MINIMAL 15-20 PCT POPS REMAIN IN THE FCST. THE COLDER AIR WITH 900 MB TEMPS TO AROUND 3C ARRIVE SATURDAY MORNING ALONG WITH POTENTIAL FOR SOME LIGHT LAKE EFFECT PCPN GIVEN SFC TEMP NEAR 16C ON THE SOUTH END OF LAKE SUPERIOR. HOWEVER... 850-700 MB DRYING WILL NOT BE FAVORABLE FOR MORE THAN BRIEF DRIZZLE/SPRINKLES. OTHERWISE...DRY ADVECTION WITH MIXING AND DIVERGENT FLOW SHOULD BRING PARTLY SUNNY SKIES DURING THE AFTERNOON WITH MORE EARLY FALL-LIKE MAX READINGS IN THE UPPER 500S NORTH TO THE MID 60S SOUTH. SUNDAY...THE 18Z/00Z GFS AND ENSEMBLE SUGGEST POTENTIAL FOR WAA PCPN WITH SRLY 850-700 MB FLOW DEVELOPING AND MOISTURE MOVING TOWARD THE AREA FROM THE MS VALLEY. HOWEVER...SINCE THE 12Z/00Z ECMWF AND UKMET REMAIN DRY...WILL HOLD OFF ON ADDING MENTION OF PCPN YET. EVEN THOUGH THE GFS ENSEMBLE MEAN REMAINS SLOWER THAN THE OPERATIONAL MODEL...TRENDS FROM 12Z/00Z AND 06Z/12Z GFS SUPPORT SLIGHTLY FASTER PATTERN PROGRESSION AND ADDITION OF SLIGHT CHANCE POPS OVER THE CNTRL/E CWA WED . OTHERWISE...NO ADDITIONAL CHANGES MON-THU. .AVIATION (FOR THE 18Z TAF ISSUANCE)... GUSTY WINDS OCCURRING AT BOTH TAF SITES DUE TO A TIGHT PRESSURE GRADIENT BETWEEN TWO COLD FRONTS DROPPING DOWN FROM CANADA AND HIGH PRESSURE OVER SE ONTARIO. IN ADDITION...WARM MOIST AIR BEING PULLED INTO THE AREA IS SUPPORTING MID LEVEL CLOUDS...WITH A FEW SHOWERS AND THUNDERSTORMS ACROSS WESTERN LAKE SUPERIOR. ONLY CONFIDENT RIGHT NOW TO INCLUDE A 3 HOUR TEMPO GROUP FOR CMX WITH A VFR CIG AND CB GROUP. ALL OF THE PCPN IS MOVING SE...AND SHOULD BE AWAY FROM CMX BY 00Z AND SAW BY 06Z. WINDS DIMINISHING THIS EVENING COMBINED WITH WINDS STAYING BREEZY JUST ABOVE THE SFC SHOULD RESULT IN SOME LLWS THROUGH 06Z. THE SECOND COLD FRONT OVER CENTRAL CANADA SHOULD DROP SOUTH ACROSS THE TAF SITES AFTER 06Z...CAUSING A RAPID WIND SHIFT AND INCREASE FROM THE NORTH...ALONG WITH SOME MVFR STRATOCUMULUS. WIND DIRECTION NOT AS FAVORABLE FOR A BKN DECK AT CMX COMPARED TO SAW...SO NO CIG MENTIONED AT CMX. WINDS SHOULD DIMINISH LATE SAT MRNG AS HIGH PRESSURE BEGINS NOSING IN BEHIND THE COLD FRONT. MVFR CLOUDS AT SAW WILL LIKELY BREAK UP JUST AFTER 18Z. && .MARINE (FOR THE 10 AM LAKE SUPERIOR FORECAST ISSUANCE)... 10 AM UPDATE...WINDS HAVE FAILED SO FAR ON WESTERN LAKE SUPERIOR TO REACH GALE FORCE. LOOKING AT MODELS...IT APPEARS WINDS SHOULD STAY UNDER GALES ON WESTERN SUPERIOR THROUGH THE AFTERNOON. THEREFORE THE GALE WARNING FOR 263 AND 264 HAS BEEN CANCELLED. EASTERN LAKE SUPERIOR HAS BEEN ON THE FRINGE OF GALES THIS MORNING...WITH THE EASTERN BUOY AMAZINGLY HAVING A FEW HOURS OF GUSTS TO 33 KT...PRETTY HIGH FOR THAT BUOY ON A SOUTH WIND CONSIDERING THE ANEMOMETER IS BELOW THE FORECAST WIND HEIGHT LEVEL. WINDS SHOULD DIMINISH ON EASTERN SUPERIOR AROUND NOON...SO GALE WARNING END TIME LOOKS GOOD. ALSO...HAVE PUT UP A GALE WATCH FOR LATER TONIGHT AS THE PRESSURE RISES QUICKLY BEHIND A STRONG COLD FRONT. THERE REMAINS ENOUGH UNCERTAINTY TO ISSUE ANY GALE WARNING AT THIS TIME. DECISION ON WARNING WILL BE MADE WITH THE 4 PM ISSUANCE. TIGHT PRESSURE GRADIENT WILL EXIST OVER LAKE SUPERIOR TODAY AS A COLD FRONT OVER NORTH CENTRAL CANADA SETTLES OVER THUNDER BAY ONTARIO BY THIS EVENING. SOUTHWEST WINDS WILL INCREASE TO 30 KNOTS THIS MORNING...WITH FREQUENT GALE FORCE GUSTS OVER LAKE SUPERIOR THROUGH THIS MORNING. A FEW GALE FORCE GUSTS ARE ALSO POSSIBLE ON WEST AND NORTH CENTRAL LAKE SUPERIOR. AS THE FRONT NEARS...WINDS WILL SLOWLY DECREASE THIS AFTERNOON AS GRADIENTS WEAKEN. NORTHERLY STRONG WINDS BEHIND THE FRONT WILL BE RELATIVELY BRIEF AND SHOULD END BY SUNRISE SATURDAY AS HIGH PRESSURE MOVES INTO THE REGION. WINDS WILL BE LESS THAN 20 KNOTS ON SUNDAY AS THE HIGH PRESSURE RIDGE CONTINUES TO DRIFT ACROSS THE REGION. SOUTH WINDS WILL INCREASE ON THE BACK SIDE OF THIS HIGH BY EARLY NEXT WEEK WITH WINDS UP TO 30 KNOTS STARTING UP AS EARLY AS NEXT TUESDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... GALE WARNING UNTIL NOON EDT TODAY FOR LSZ266-267. GALE WATCH FROM LATE TONIGHT THROUGH SATURDAY MORNING FOR LSZ264-266-267. LAKE MICHIGAN...NONE. && $$ DISCUSSION...JLB AVIATION...AJ MARINE...DLG/AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 945 AM EDT FRI SEP 19 2008 UPDATED MARINE DISCUSSION AND WATCH/WARNING/ADVISORY SECTIONS .DISCUSSION... WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL MID/UPPER LEVEL FLOW ACROSS MOST OF THE NRN CONUS DOWNSTREAM FROM A RIDGE OVER WRN NOAM. THE MOST PROMINENT SHORTWAVE TROUGH OVER THE REGION WAS WELL TO THE NORTH OVER NRN MANITOBA WITH A WEAKER/SHEARED SHRTWV FARTHER S FROM WRN ONTARIO INTO THE CNTRL DAKOTAS. AT THE SFC...A 996 MB LOW WAS LOCATED OVER NE MANITOBA WITH A COLD FRONT THROUGH LK WINNIPEG INTO SRN SASK. A TROUGH ALSO EXTENDED FROM SE MANITOBA INTO CNTRL SD. STRONG SSW FLOW INTO UPPER MI AND LK SUPERIOR...PER KMQT VAD WIND PRFL 45 KT 2K FT WIND...WITH STRONG 925-800 MB THETA-E ADVECTION AND ASSOCIATED 300K-305K ISENTROPIC ASCENT SUPPORTED SHRA/TSRA OVER NE LAKE SUPERIOR AND SOME ISOLD LIGHT SHOWERS INTO N CNTRL UPPER MI. TODAY...EXPECT THE ISOLD SHOWERS OVER N CNTRL UPPER MI TO PROGRESS TO THE EAST BEFORE 12Z. ADDITIONAL SLIGHT CHANCE FOR SHRA/TSRA WILL BE SUPPORTED BY A BAND OF 305K-310K ISENTROPIC LIFT AHEAD OF THE TROUGH AND DAKOTAS SHRTWV. TS POTENTIAL REMAINS WITH MUCAPE VALUES IN THE 200-400 J/KG RANGE ASSOCIATED WITH STEEP 700-500 MB LAPSE RATES AROUND 7.5 C/KM. 850 MB TEMPS TO AROUND 14C AND DECENT MIXING WITH SOME SUNSHINE AND STIFF SW WINDS WILL SUPPORT MAX READINGS INTO THE UPPER 70S. TONIGHT INTO SATURDAY...AS THE NRN MANITOBA SHRTWV AND SFC LOW MOVES INTO NRN QUEBEC...A COLD FRONT WILL PLUNGE SOUTHEASTWARD THROUGH THE UPPER GREAT LAKES. A BAND OF 900-800 MB FGEN WITH THE SHARP TEMP GRADIENT COULD PRODUCE A FEW LIGHT SHOWERS TONIGHT. HOWEVER SINCE MOISTURE WILL BE LIMITED/SHALLOW ONLY MINIMAL 15-20 PCT POPS REMAIN IN THE FCST. THE COLDER AIR WITH 900 MB TEMPS TO AROUND 3C ARRIVE SATURDAY MORNING ALONG WITH POTENTIAL FOR SOME LIGHT LAKE EFFECT PCPN GIVEN SFC TEMP NEAR 16C ON THE SOUTH END OF LAKE SUPERIOR. HOWEVER... 850-700 MB DRYING WILL NOT BE FAVORABLE FOR MORE THAN BRIEF DRIZZLE/SPRINKLES. OTHERWISE...DRY ADVECTION WITH MIXING AND DIVERGENT FLOW SHOULD BRING PARTLY SUNNY SKIES DURING THE AFTERNOON WITH MORE EARLY FALL-LIKE MAX READINGS IN THE UPPER 500S NORTH TO THE MID 60S SOUTH. SUNDAY...THE 18Z/00Z GFS AND ENSEMBLE SUGGEST POTENTIAL FOR WAA PCPN WITH SRLY 850-700 MB FLOW DEVELOPING AND MOISTURE MOVING TOWARD THE AREA FROM THE MS VALLEY. HOWEVER...SINCE THE 12Z/00Z ECMWF AND UKMET REMAIN DRY...WILL HOLD OFF ON ADDING MENTION OF PCPN YET. EVEN THOUGH THE GFS ENSEMBLE MEAN REMAINS SLOWER THAN THE OPERATIONAL MODEL...TRENDS FROM 12Z/00Z AND 06Z/12Z GFS SUPPORT SLIGHTLY FASTER PATTERN PROGRESSION AND ADDITION OF SLIGHT CHANCE POPS OVER THE CNTRL/E CWA WED . OTHERWISE...NO ADDITIONAL CHANGES MON-THU. .AVIATION (FOR THE 12Z TAF ISSUANCE)... LLWS TO PERSIST OVER BOTH TAF SITES THROUGH EARLY MORNING HOURS AND AGAIN THIS EVENING OVER BOTH LOCATIONS. ONCE DAYTIME MIXING KICKS IN...MIXING WILL PRODUCE GUSTY CONDITIONS THROUGH THE DAY UNTIL THE SURFACE GRADIENT RELAXES LATE IN THE AFTERNOON. AFOREMENTIONED WARM AIR ADVECTION TO BRING MID/HIGH CLOUDS TO THE REGION DURING THE DAY...AND MAY ALSO PRODUCE ISOLATED SHOWERS AND PERHAPS A THUNDERSTORM. PROBABILITIES FOR THIS ARE QUITE LOW AS LOWER LEVELS STILL FAIRLY DRY PER LATEST BUFKIT SOUNDINGS SO WILL LEAVE OUT MENTION FOR NOW. WINDS WILL VEER NORTH FOLLOWING THE FROPA. GUIDANCE POINTS TO SOME LOW CLOUDS WILL BE POSSIBLE FOR A SHORT TIME FOLLOWING THE FROPA ALSO. && .MARINE (FOR THE 10 AM LAKE SUPERIOR FORECAST ISSUANCE)... 10 AM UPDATE...WINDS HAVE FAILED SO FAR ON WESTERN LAKE SUPERIOR TO REACH GALE FORCE. LOOKING AT MODELS...IT APPEARS WINDS SHOULD STAY UNDER GALES ON WESTERN SUPERIOR THROUGH THE AFTERNOON. THEREFORE THE GALE WARNING FOR 263 AND 264 HAS BEEN CANCELLED. EASTERN LAKE SUPERIOR HAS BEEN ON THE FRINGE OF GALES THIS MORNING...WITH THE EASTERN BUOY AMAZINGLY HAVING A FEW HOURS OF GUSTS TO 33 KT...PRETTY HIGH FOR THAT BUOY ON A SOUTH WIND CONSIDERING THE ANEMOMETER IS BELOW THE FORECAST WIND HEIGHT LEVEL. WINDS SHOULD DIMINISH ON EASTERN SUPERIOR AROUND NOON...SO GALE WARNING END TIME LOOKS GOOD. ALSO...HAVE PUT UP A GALE WATCH FOR LATER TONIGHT AS THE PRESSURE RISES QUICKLY BEHIND A STRONG COLD FRONT. THERE REMAINS ENOUGH UNCERTAINTY TO ISSUE ANY GALE WARNING AT THIS TIME. DECISION ON WARNING WILL BE MADE WITH THE 4 PM ISSUANCE. TIGHT PRESSURE GRADIENT WILL EXIST OVER LAKE SUPERIOR TODAY AS A COLD FRONT OVER NORTH CENTRAL CANADA SETTLES OVER THUNDER BAY ONTARIO BY THIS EVENING. SOUTHWEST WINDS WILL INCREASE TO 30 KNOTS THIS MORNING...WITH FREQUENT GALE FORCE GUSTS OVER LAKE SUPERIOR THROUGH THIS MORNING. A FEW GALE FORCE GUSTS ARE ALSO POSSIBLE ON WEST AND NORTH CENTRAL LAKE SUPERIOR. AS THE FRONT NEARS...WINDS WILL SLOWLY DECREASE THIS AFTERNOON AS GRADIENTS WEAKEN. NORTHERLY STRONG WINDS BEHIND THE FRONT WILL BE RELATIVELY BRIEF AND SHOULD END BY SUNRISE SATURDAY AS HIGH PRESSURE MOVES INTO THE REGION. WINDS WILL BE LESS THAN 20 KNOTS ON SUNDAY AS THE HIGH PRESSURE RIDGE CONTINUES TO DRIFT ACROSS THE REGION. SOUTH WINDS WILL INCREASE ON THE BACK SIDE OF THIS HIGH BY EARLY NEXT WEEK WITH WINDS UP TO 30 KNOTS STARTING UP AS EARLY AS NEXT TUESDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... GALE WARNING UNTIL NOON EDT TODAY FOR LSZ266-267. GALE WATCH FROM LATE TONIGHT THROUGH SATURDAY MORNING FOR LSZ264-266-267. LAKE MICHIGAN...NONE. && $$ DISCUSSION...JLB AVIATION...DLG MARINE...DLG/AJ mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 731 AM EDT FRI SEP 19 2008 .DISCUSSION... WV IMAGERY AND RUC ANALYSIS INDICATED A MAINLY ZONAL MID/UPPER LEVEL FLOW ACROSS MOST OF THE NRN CONUS DOWNSTREAM FROM A RIDGE OVER WRN NOAM. THE MOST PROMINENT SHORTWAVE TROUGH OVER THE REGION WAS WELL TO THE NORTH OVER NRN MANITOBA WITH A WEAKER/SHEARED SHRTWV FARTHER S FROM WRN ONTARIO INTO THE CNTRL DAKOTAS. AT THE SFC...A 996 MB LOW WAS LOCATED OVER NE MANITOBA WITH A COLD FRONT THROUGH LK WINNIPEG INTO SRN SASK. A TROUGH ALSO EXTENDED FROM SE MANITOBA INTO CNTRL SD. STRONG SSW FLOW INTO UPPER MI AND LK SUPERIOR...PER KMQT VAD WIND PRFL 45 KT 2K FT WIND...WITH STRONG 925-800 MB THETA-E ADVECTION AND ASSOCIATED 300K-305K ISENTROPIC ASCENT SUPPORTED SHRA/TSRA OVER NE LAKE SUPERIOR AND SOME ISOLD LIGHT SHOWERS INTO N CNTRL UPPER MI. TODAY...EXPECT THE ISOLD SHOWERS OVER N CNTRL UPPER MI TO PROGRESS TO THE EAST BEFORE 12Z. ADDITIONAL SLIGHT CHANCE FOR SHRA/TSRA WILL BE SUPPORTED BY A BAND OF 305K-310K ISENTROPIC LIFT AHEAD OF THE TROUGH AND DAKOTAS SHRTWV. TS POTENTIAL REMAINS WITH MUCAPE VALUES IN THE 200-400 J/KG RANGE ASSOCIATED WITH STEEP 700-500 MB LAPSE RATES AROUND 7.5 C/KM. 850 MB TEMPS TO AROUND 14C AND DECENT MIXING WITH SOME SUNSHINE AND STIFF SW WINDS WILL SUPPORT MAX READINGS INTO THE UPPER 70S. TONIGHT INTO SATURDAY...AS THE NRN MANITOBA SHRTWV AND SFC LOW MOVES INTO NRN QUEBEC...A COLD FRONT WILL PLUNGE SOUTHEASTWARD THROUGH THE UPPER GREAT LAKES. A BAND OF 900-800 MB FGEN WITH THE SHARP TEMP GRADIENT COULD PRODUCE A FEW LIGHT SHOWERS TONIGHT. HOWEVER SINCE MOISTURE WILL BE LIMITED/SHALLOW ONLY MINIMAL 15-20 PCT POPS REMAIN IN THE FCST. THE COLDER AIR WITH 900 MB TEMPS TO AROUND 3C ARRIVE SATURDAY MORNING ALONG WITH POTENTIAL FOR SOME LIGHT LAKE EFFECT PCPN GIVEN SFC TEMP NEAR 16C ON THE SOUTH END OF LAKE SUPERIOR. HOWEVER... 850-700 MB DRYING WILL NOT BE FAVORABLE FOR MORE THAN BRIEF DRIZZLE/SPRINKLES. OTHERWISE...DRY ADVECTION WITH MIXING AND DIVERGENT FLOW SHOULD BRING PARTLY SUNNY SKIES DURING THE AFTERNOON WITH MORE EARLY FALL-LIKE MAX READINGS IN THE UPPER 500S NORTH TO THE MID 60S SOUTH. SUNDAY...THE 18Z/00Z GFS AND ENSEMBLE SUGGEST POTENTIAL FOR WAA PCPN WITH SRLY 850-700 MB FLOW DEVELOPING AND MOISTURE MOVING TOWARD THE AREA FROM THE MS VALLEY. HOWEVER...SINCE THE 12Z/00Z ECMWF AND UKMET REMAIN DRY...WILL HOLD OFF ON ADDING MENTION OF PCPN YET. EVEN THOUGH THE GFS ENSEMBLE MEAN REMAINS SLOWER THAN THE OPERATIONAL MODEL...TRENDS FROM 12Z/00Z AND 06Z/12Z GFS SUPPORT SLIGHTLY FASTER PATTERN PROGRESSION AND ADDITION OF SLIGHT CHANCE POPS OVER THE CNTRL/E CWA WED . OTHERWISE...NO ADDITIONAL CHANGES MON-THU. .AVIATION (FOR THE 12Z TAF ISSUANCE)... LLWS TO PERSIST OVER BOTH TAF SITES THROUGH EARLY MORNING HOURS AND AGAIN THIS EVENING OVER BOTH LOCATIONS. ONCE DAYTIME MIXING KICKS IN...MIXING WILL PRODUCE GUSTY CONDITIONS THROUGH THE DAY UNTIL THE SURFACE GRADIENT RELAXES LATE IN THE AFTERNOON. AFOREMENTIONED WARM AIR ADVECTION TO BRING MID/HIGH CLOUDS TO THE REGION DURING THE DAY...AND MAY ALSO PRODUCE ISOLATED SHOWERS AND PERHAPS A THUNDERSTORM. PROBABILITIES FOR THIS ARE QUITE LOW AS LOWER LEVELS STILL FAIRLY DRY PER LATEST BUFKIT SOUNDINGS SO WILL LEAVE OUT MENTION FOR NOW. WINDS WILL VEER NORTH FOLLOWING THE FROPA. GUIDANCE POINTS TO SOME LOW CLOUDS WILL BE POSSIBLE FOR A SHORT TIME FOLLOWING THE FROPA ALSO. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... TIGHT PRESSURE GRADIENT WILL EXIST OVER LAKE SUPERIOR TODAY AS A COLD FRONT OVER NORTH CENTRAL CANADA SETTLES OVER THUNDER BAY ONTARIO BY THIS EVENING. SOUTHWEST WINDS WILL INCREASE TO 30 KNOTS THIS MORNING...WITH FREQUENT GALE FORCE GUSTS OVER LAKE SUPERIOR THROUGH THIS MORNING. A FEW GALE FORCE GUSTS ARE ALSO POSSIBLE ON WEST AND NORTH CENTRAL LAKE SUPERIOR. AS THE FRONT NEARS...WINDS WILL SLOWLY DECREASE THIS AFTERNOON AS GRADIENTS WEAKEN. NORTHERLY STRONG WINDS BEHIND THE FRONT WILL BE RELATIVELY BRIEF AND SHOULD END BY SUNRISE SATURDAY AS HIGH PRESSURE MOVES INTO THE REGION. WINDS WILL BE LESS THAN 20 KNOTS ON SUNDAY AS THE HIGH PRESSURE RIDGE CONTINUES TO DRIFT ACROSS THE REGION. SOUTH WINDS WILL INCREASE ON THE BACK SIDE OF THIS HIGH BY EARLY NEXT WEEK WITH WINDS UP TO 30 KNOTS STARTING UP AS EARLY AS NEXT TUESDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR...GALE WARNING TIL 12 PM EDT TODAY FOR LSZ266-267. GALE WARNING FROM 8AM EDT UNTIL 5 PM EDT THIS AFTERNOON FOR LSZ263-264. LAKE MICHIGAN...NONE. && DLG $$ DISCUSSION...JLB AVIATION...DLG MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 724 AM EDT FRI SEP 19 2008 .SYNOPSIS.../ISSUED AT 350 AM/ HIGH PRESSURE OVER THE EASTERN GREAT LAKES WILL SLIDE EAST TOWARDS THE ATLANTIC COAST WHILE LOW PRESSURE TRACKS ACROSS HUDSON BAY. THIS LOW PRESSURE WILL DRAG A COLD FRONT ACROSS THE REGION LATE FRIDAY NIGHT INTO SATURDAY WITH ONLY VERY SMALL CHANCES OF THUNDERSTORMS EXPECTED. OTHERWISE...DRY CONDITIONS ARE EXPECTED THROUGH EARLY NEXT WEEK. MPC && .SHORT TERM.../ISSUED AT 350 AM/...TODAY 02Z SURFACE/RUC ANALYSIS AND IR/WV/RADAR IMAGERY SHOW STRONG 1031MB HIGH PRESSURE CENTERED OVER THE FAR EASTERN GREAT LAKES...WHICH EXTENDS WESTWARD INTO NORTHERN MICHIGAN. MEANWHILE...IMPRESSIVE LOOKING SHORTWAVE IS DROPPING SOUTHEAST NORTH OF LAKE WINNIPEG. SURFACE LOW PRESSURE AHEAD OF THIS WAVE HAS A SURFACE TROUGH WHICH EXTENDS SOUTH ACROSS THE DAKOTAS...AND A WARM FRONTAL LIKE FEATURE ACROSS CENTRAL ONTARIO. WARM ADVECTION/MOISTURE ADVECTION ON NOSE OF A 50KT LLJ IS GENERATING SHOWERS AND STORMS NORTH OF LAKE SUPERIOR...WHICH IS HEADING EAST WELL NORTH OF THE REGION...WHILE CONVECTION ALONG THE SURFACE TROUGH IS WIDELY SCT DESPITE MID-LEVEL THETAE RIDGE AND ELEVATED INSTABILITY. MAIN FORECAST CONCERNS IN THE FIRST 12 HOURS INCLUDE MARINE HEADLINES AS THE PRESSURE GRADIENT TIGHTENS BETWEEN THE DEPARTING SURFACE HIGH AND APPROACHING SURFACE TROUGH...THEN PRECIP CHANCES FRIDAY NIGHT INTO SATURDAY WITH THE PASSAGE OF THE SURFACE TROUGH. TODAY...SURFACE HIGH PRESSURE LIFTS NE INTO THE WESTERN ATLANTIC OCEAN WHILE THE SURFACE LOW PRESSURE AHEAD OF THE POTENT SHORTWAVE OVER CENTRAL CANADA TRACKS ACROSS SOUTHERN HUDSON BAY. NARROW MOISTURE CHANNEL/THETAE RIDGE WILL SURGE AHEAD OF THE SURFACE TROUGH AS IT SHIFTS ACROSS THE NORTHERN GREAT LAKES AND HEADS TOWARDS EASTERN UPPER. SOME FAIRLY STEEP MID-LEVEL LAPSE RATES WILL BE PRESENT WITHIN THIS MOISTURE PLUME...BUT WE ARE NOT REALLY TALKING ABOUT THAT MUCH MOISTURE...AND MODEL SOUNDINGS INDICATE THAT MOST OF THIS MOISTURE IS ABOVE 600MB...SO DO NOT BELIEVE THERE IS MUCH OF A CHANCE OF PRECIP. OUTSIDE OF THESE CLOUDS...SOME OCCASIONAL WARM ADVECTION CLOUDS WILL PASS ACROSS THE AREA...BUT MOST OF THE AREA WILL SEE A GOOD DEAL OF SUNSHINE. BREEZY SOUTHWEST WINDS WILL USHER IN WARMER AIR WITH HIGHS IN THE LOW TO MID 70S. MPC && .LONG TERM.../ISSUED AT 350 AM/...TONIGHT AND BEYOND TONIGHT...STRONGER COLD FRONT ACROSS WEST CENTRAL CANADA CATCHES UP WITH THE SURFACE TROUGH AS THEY MOVE ACROSS LAKE SUPERIOR TONIGHT AND APPROACH EASTERN UPPER BY MORNING. THERE IS SOME DECENT 850-700MB -DIV Q AHEAD OF THE FRONT WHILE SOME STRONG 850-700MB FGEN RESIDES BEHIND BOUNDARY...BUT ALL UPPER LEVEL SUPPORT WILL PASS WELL NORTH OF THE REGION. HOWEVER...MOISTURE IS LACKING ALONG AND BEHIND THE FRONT WITHIN THE FORCING AREA AND HAVE A HARD TIME THINKING PRECIP IS POSSIBLE JUDGING BY THE DRYNESS OF MODEL SOUNDINGS ABOVE 900MB. IN FACT...LOOKING UPSTREAM ACROSS CANADA...ONLY MID AND HIGH CLOUDS ARE PRESENT ALONG THE FRONT. SO...WILL YANK ALREADY SMALL PRECIP CHANCES AND JUST SHOW A GENERAL INCREASE IN CLOUDINESS...WHICH WAS ALREADY IN THE FORECAST. A BREEZY AND WARM NIGHT...WITH LOWS IN THE MID 50S TO LOW 60S. SATURDAY AND SATURDAY NIGHT...COLD FRONT PASSES ACROSS THE REST OF EASTERN UPPER AND ALL OF NORTHERN LOWER BY SATURDAY AFTERNOON. MOISTURE REMAINS LIMITED ALONG THE FRONT SO STILL BELIEVE MOST AREAS WILL STAY DRY. BUT KIND OF INTERESTING...MODIFYING A NAM40 SOUNDING AT 21Z NEAR WEST BRANCH YIELDS 500 J/KG OF ML CAPE WITH ONLY 29 J/KG OF CIN...WHICH CONVERGENCE ALONG THE FRONT SHOULD BE ABLE TO OVERCOME. WILL ALLOW SOME MARGIN OF ERROR HERE AND MAINTAIN A 20 CHANCE OF THUNDERSTORMS SOUTH OF A LAND FROM FRANKFORT TO ALPENA. FRONT SAGS SOUTH OF THE REGION SATURDAY NIGHT AND HIGH PRESSURE BUILDS IN. NAM/GFS DROP 850MB TEMPS TO AROUND 2C ACROSS EASTERN UPPER WHICH IS A GOOD 2-4C COOLER THAN THE ECMWF. IF THE NAM/GFS SOLUTIONS COMES TO PASS AND HIGH CLOUDS DO NOT FILTER IN...PERHAPS SOME PATCHY FROST IS POSSIBLE ACROSS EASTERN UPPER IN THE COOL SPOTS NEAR RACO. SUNDAY THROUGH TUESDAY...LITTLE CHANGE TO THE GOING FORECAST OVER THIS PERIOD. GENERAL UPPER AIR PATTERN WILL CONSIST OF TROUGHING ACROSS THE NORTHERN ROCKIES AND POINTS WEST...AND RIDGING FROM THE MISSISSIPPI RIVER VALLEY TO THE EAST. THIS RIDGE WILL PREVENT SHORTWAVES ROUNDING THE BASE OF THE TROUGH TO REACH THE GREAT LAKES. RATHER...THEY WILL BE SHUNTED TO THE NE INTO CENTRAL CANADA. AS A RESULT...HIGH PRESSURE WILL BE PRESENT ACROSS THE GREAT LAKES SUNDAY AND MONDAY BEFORE SHIFTING TO THE EAST ON TUESDAY. THIS WILL MAINTAIN THE EXTENDED PERIOD OF DRY WEATHER WITH TEMPERATURES WARMING THROUGH THE PERIOD AS RETURN FLOW GRADUALLY BECOMES ESTABLISHED. HIGHS WILL BE COMFORTABLY IN THE MID 60S TO MID 70S RANGE AND MINS WILL RANGE FROM THE MID 40S TO MID 50S. MPC && .MARINE.../ISSUED AT 350 AM/ PRESSURE GRADIENT TIGHTENS EARLY THIS MORNING AND REMAINS TIGHT THROUGH TONIGHT UNTIL A SURFACE TROUGH PASSES THE AREA. NAM12 SHOWS 40 TO 45 KNOTS OVER NORTHERN LAKE MICHIGAN AND AROUND WHITEFISH POINT THROUGH AROUND 8AM SAT MORNING. ALTHOUGH WE ARE NEUTRAL IN TERMS OF STABILITY...MIXING COMBINED WITH COASTAL CONVERGENCE MAY BE ENOUGH TO GET A FEW GALE FORCE GUSTS TO SURFACE. IF GALES DO OCCUR DURING THE DAY...THEY MAY HAVE TO BE EXTENDED LONGER INTO TONIGHT. WILL LET THE DAY CREW ASSESS HOW THINGS ARE GOING. MPC && .AVIATION.../ISSUED AT 723 AM/...VALID FOR 12Z TAFS VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD. TIGHT PRESSURE GRADIENT BETWEEN HIGH PRESSURE TO THE EAST AND LOW PRESSURE TO THE NORTHWEST WILL CREATE BREEZY SOUTHWEST WINDS TODAY. AS SURFACE WINDS DIMINISH SOMEWHAT THIS EVENING...WIND SHEAR WILL DEVELOP RIGHT OFF THE SURFACE AT ALL TAF SITES AND CONTINUE THROUGH THE NIGHT. MPC && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 5 AM EDT SATURDAY FOR LMZ323-346. GALE WARNING UNTIL 11 PM EDT THIS EVENING FOR LMZ341-342-344-345. LH...SMALL CRAFT ADVISORY UNTIL 5 AM EDT SATURDAY FOR LHZ345>349. LS...SMALL CRAFT ADVISORY UNTIL 5 AM EDT SATURDAY FOR LSZ321-322. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 125 AM EDT FRI SEP 19 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAF ISSUANCE .SYNOPSIS... 19Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING ACROSS MUCH OF THE CONUS...WITH THE MAIN WESTERLIES IN A WNW FLOW ORIENTATION IN SOUTHERN CANADA. THE MAIN FEATURE TO NOTE IS A POTENT LOOKING SHRTWV IN NE ALBERTA. OVER UPPER MI...THE WEATHER HAS BEEN QUIET...THANKS TO LOW TO MID-LEVEL DRY AIR ROTATING AROUND A 1032MB HIGH SITUATED NEAR GEORGIAN BAY. THE LOW LEVEL AIR HAS NOT BEEN COMPLETELY DRY...THOUGH...AND THIS WAS EVIDENT BY A STRATUS DECK THAT HAS BEEN SLOWLY MIXING OUT OVER SOUTH CENTRAL UPPER MI. TAMDAR SOUNDINGS SHOWED A SHARP INVERSION FROM 900MB TO THE SFC...AND SE WINDS WERE ADVECTING MOISTURE OFF LAKE MICHIGAN UP THE MENOMINEE RIVER. ENOUGH DAYTIME HEATING HAS OCCURRED NOW TO MIX SOME OF THE DRIER AIR ABOVE 900MB TO THE SFC...ALLOWING THE CLOUDS TO BREAK UP. TO OUR SOUTH...DIURNAL CUMULUS CAN BE SEEN OVER EASTERN IA WHERE DEWPOINTS ARE IN THE LOW 60S. TO THE WEST...VERY WARM TEMPS ARE SEEN ACROSS THE DAKOTAS...WITH BISMARCK AT 90 AS OF 19Z. THE 850MB TEMP THERE AT 12Z WAS 20C...COMPARED TO 11C AT INL...2C AT PICKLE LAKE ONTARIO AND -9C AT MOOSONEE ONTARIO. WELL OFF TO THE NW ASSOCIATED WITH THE SHRTWV...A 1002MB LOW AS OVER FAR NRN MANITOBA...WITH A TROUGH EXTENDING DOWN THE LEE OF THE ROCKIES AND A COLD FRONT EXTENDING WEST THROUGH ALBERTA. IN YELLOWKNIFE...IT IS 41 F WITH -DZ AND A GUSTY NW WIND...A SIGN OF AIR TO COME FOR EARLY THIS WEEKEND. && .SHORT TERM (TONIGHT AND FRI)... SHRTWV TROUGH OVER NE ALBERTA WILL BE MOVING SOUTHEAST DURING THE NEXT 24 HOURS...REACHING FAR NW ONTARIO BY 00Z SAT. AS THIS OCCURS...IT WILL DRIVE THE COLD FRONT IN NORTHERN ALBERTA THROUGH MUCH OF NW ONTARIO...REACHING THUNDER BAY BY 00Z SAT. THEREFORE UPPER MICHIGAN IS GOING TO BE UNDER A WARM ADVECTION REGIME... BRINGING SOME OF THAT WARM AIR SEEN OVER IN BISMARCK EASTWARD ACROSS UPPER MI. 850MB TEMPS CLIMB FROM THE CURRENT 6-10C READINGS PER RUC ANALYSIS TO AROUND 14C FOR THE DAY FRIDAY. TONIGHT...TEMPERATURES SHOULD STRUGGLE FALLING MUCH WITH A BREEZY SW WIND...ESPECIALLY NEAR THE SHORELINES. WARMEST READINGS WILL BE IN THE WESTERN U.P. WHERE LOWS ARE NOT EXPECTED BELOW 60. THE QUESTION IS HOW MUCH DOES IT COOL DOWN A FEW THOUSAND FEET OFF THE SURFACE IN THE INTERIOR OVER NORTHERN WI AND WESTERN UPPER MI. THE REASON IS THAT THE SOUTHERLY WINDS WILL BRING UP THE UPPER 50S/LOW 60S DEWPOINTS OVER EASTERN IA. IF THE AIRMASS JUST ABOVE THE SURFACE COOLS DOWN...THEN A STRATUS DECK COULD FORM OVER NRN WI AND WESTERN UPPER MI. RH PROGS AT 925 AND 900MB FROM THE GFS...NAM AND OUR LOCAL WRF-ARW RUN REFLECT THAT IDEA BY SHOWING VALUES OF OVER 90 PCT. ON THE OTHER HAND...SW WINDS DO NOT SEEM TO DEVELOP STRATUS DECKS AS WELL HERE. THEREFORE...HAVE SPLIT THE DIFFERENCE BY GOING PARTLY CLOUDY...AND SHOWING THE POSSIBILITY IN THE SKY GRIDS WITH VALUES INCREASING SW TO NE AFTER 06Z. NO PCPN WORRIES OUT OF THIS SINCE WHATEVER DECK WOULD FORM SHOULD BE THIN. FRIDAY...ISENTROPIC LIFT SEEN ON THE 310K SFC...RELATED TO THE WARM ADVECTION AHEAD OF THE SHRTWV/COLD FRONT...SHOULD RESULT IN A DECK OF MID/HIGH CLOUDS MOVING NW TO SE ACROSS UPPER MI DURING THE DAY. ALL MODELS DEPICT SOME LIGHT PCPN OCCURRING OUT OF THESE MID CLOUDS (LIKELY AN ACCAS DECK). CANNOT RULE THIS OUT DUE TO TWO FEATURES COMING IN PLAY...A WEAK ZONE OF 700-600MB FRONTOGENESIS AND RIGHT ENTRANCE REGION FORCING WITH A 50-60KT JET MOVING NW TO SE ACROSS LAKE SUPERIOR. IN ADDITION...SOUNDINGS LIFTED FROM 700MB WHEN THE MID CLOUDS ARE PRESENT INDICATE A FEW HUNDRED J/KG OF CAPE...DUE TO THE ADVECTION OF 7.5-8C/KM LAPSE RATES ACROSS THE CWA. THEREFORE 20 POPS EXIST IN THE FORECAST WITH BOTH SHOWERS AND THUNDER MENTIONED. CLOUD COVER CREATES SOME CONCERN WITH MAX TEMPS...AND HAVE LOWERED HIGHS JUST A DEGREE TO ACCOUNT FOR THE POSSIBILITY OF THICKER CLOUD COVER THAT IS INDICATED BY MODELS. EITHER WAY...IT SHOULD BE WARM WITH RESPECT TO MID SEPTEMBER READINGS...BUT STILL BELOW RECORD HIGHS WHICH ARE IN THE LOW TO MID 80S. .LONG TERM (FRI NIGHT THROUGH NEXT THU)... CHANCES OF RAIN ARE THE MAIN CONCERN FRIDAY NIGHT. GFS AND NAM IN GOOD AGREEMENT WITH UPPER AIR AND MSLP PATTERNS THROUGH THE WEEKEND. FOLLOWED THE LOCAL WRF-ARW IN ITS DEPICTION OF BRINGING COLD FRONT THROUGH LATE IN THE EVENING INTO NORTHERN LK SUPERIOR AND ACROSS ALL CWA EXCEPT FAR SOUTH MENOMINEE COUNTY BY DAYBREAK SAT. GREATEST H85 MOISTURE ADVECTION WITH THE FRONT SHIFTS INTO EASTERN CWA EARLY EVENING SO KEPT THE POPS THERE. OTHERWISE...HAVE CLOUDS DECREASING EARLY IN THE EVENING THEN INCREASING AGAIN AFTER MIDNIGHT IN WAKE OF THE COLD FRONT. H85 TEMPS DROP TO +3C BY 12Z. SOUNDINGS SHOW MOISTENING BLO H85...LIKELY SOME LK EFFECT STRATOCUMULUS CLOUDS. KEPT THE SMALL POP IN THERE OVERNIGHT...BUT RESTRICTED IT TO JUST POTENTIAL LIGHT LK EFFECT PCPN. GIVEN UPSLOPE NORTHERLY FLOW AND TEMPS AT TOP OF INVERSION NOT WARMING...WILL PROBABLY TAKE A WHILE FOR THE LK EFFECT CLOUDS TO DISSIPATE ON SATURDAY. LOW LEVEL DRYING AND HIGH PRESSURE BUILDING IN/PWAT MIN TO ENHANCE RADIATIONAL COOLING SHOULD LEAD TO CLEAR AND CALM NIGHT SATURDAY NIGHT. LOWERED GOING MINS INTO THE LWR-MID 30S TOWARD COOP MOS GUIDANCE. UPPER LEVEL TROUGH/COOLER TEMPS AROUND FOR THE WEEKEND EASES INTO EASTERN CANADA BY NEXT MON WHILE RIDGE/WARM AIR OVER SOUTHERN UNITED STATES BUILDS TOWARD GREAT LAKES. RIDGE QUITE STRONG...WITH HEIGHTS NEARING 590DAM TUE INTO WED. WARM FRONT LIFTS THROUGH UPPER MI/LAKE SUPERIOR SUN NIGHT. CONCENTRATED MOISTURE ADVECTION REMAINS NORTH AND WEST OF UPPER MICHIGAN SO ANY POPS SHOULD BE CONFINED TO LAKE SUPERIOR. SFC RIDGE IS CLOSE ENOUGH ON MON AND PERHAPS TUE AS WELL TO KEEP BLYR WINDS MAINLY FM THE SOUTH WHICH IS NOT IDEAL FOR WARMING UP TOO MUCH. STILL...GIVEN H85 TEMPS ARE WARMING ABOVE +10C EXPECT AREAS AWAY FM LAKE MICHIGAN TO HAVE HIGH TEMPS INTO THE MID-UPR 70S AND COULD EVEN SEE LWR 80S OVR WEST CWA. COLD FRONT STILL ON TRACK TO MOVE THROUGH ON WED-THU. FOLLOWED ECMWF...UKMET... AND CANADIAN IDEA WITH A SLOWER FROPA THAN GFS SHOWED. INTERESTING NOW THOUGH THAT THE 12Z GFS/ECMWF FLIPPED WITH THE GFS SLOWER AND THE ECMWF MORE PROGRESSIVE. CHANGES TO POPS WERE MINIMAL AND ESSENTIALLY KEPT THE HIGHEST POPS OVR THE WEST WEDNESDAY AND ACROSS REST OF THE AREA WEDNESDAY NIGHT AND THURSDAY. DEPENDING ON CLOUD COVER FOR WED...HIGH TEMPS MAY REACH WELL INTO THE 70S AND POSSIBLY LWR 80S AGAIN AS WINDS BECOME SW AHEAD OF THE COLD FRONT. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... LLWS TO PERSIST OVER BOTH TAF SITES THROUGH THE NIGHT. ONCE DAYTIME MIXING KICKS IN...MIXING WILL PRODUCE GUSTY CONDITIONS THROUGH THE DAY UNTIL THE GRADIENT RELAXES LATE IN THE AFTERNOON. AFOREMENTIONED WARM AIR ADVECTION TO BRING MID/HIGH CLOUDS TO THE REGION DURING THE DAY...AND MAY ALSO PRODUCE ISOLATED SHOWERS AND PERHAPS A THUNDERSTORM. PROBABILITIES FOR THIS ARE QUITE LOW AS LOWER LEVELS STILL FAIRLY DRY PER LATEST BUFKIT SOUNDINGS SO WILL LEAVE OUT MENTION FOR NOW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... TIGHT PRESSURE GRADIENT WILL EXIST OVER LAKE SUPERIOR TONIGHT AND FRIDAY AS A COLD FRONT OVER NORTH CENTRAL CANADA DROPS DOWN TO THUNDER BAY ONTARIO BY FRIDAY EVENING. EXPECT SOUTHWEST WINDS TO INCREASE TO 30 KNOTS THIS EVENING...WITH FREQUENT GALE FORCE GUSTS OVER EASTERN LAKE SUPERIOR LATE TONIGHT THROUGH FRIDAY MORNING. A FEW GALE FORCE GUSTS ARE ALSO POSSIBLE ON WEST AND NORTH CENTRAL LAKE SUPERIOR. AS THE FRONT NEARS...WINDS WILL SLOWLY DECREASE. THE DECREASE IN WINDS WILL BE SHORT LIVED AS ANOTHER POTENTIAL GALE DEVELOPS LATER FRIDAY EVENING...THIS TIME BEHIND THE FRONT DUE TO STRONG COLD AIR ADVECTION. NORTHERLY GALES WILL BE RELATIVELY BRIEF AND SHOULD END BY SUNRISE SATURDAY AS HIGH PRESSURE MOVES INTO THE REGION. WINDS LESS THAN 20 KNOTS ON INTO SUNDAY AS THE HIGH PRESSURE RIDGE CONTINUES TO DRIFT ACROSS. SOUTH WINDS INCREASE ON BACK SIDE OF THIS HIGH BY EARLY NEXT WEEK WITH WINDS UP TO 30 KNOTS STARTING UP AS EARLY AS NEXT TUESDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... GALE WARNING FROM 4 AM TO 12 PM EDT FRIDAY FOR LSZ266-267. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/SHORT TERM...AJ LONG TERM...JLA AVIATION...RJT MARINE...AJ/JLA mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 735 PM EDT THU SEP 18 2008 UPDATED AVIATION DISCUSSION FOR 00Z TAF ISSUANCE .SYNOPSIS... 19Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING ACROSS MUCH OF THE CONUS...WITH THE MAIN WESTERLIES IN A WNW FLOW ORIENTATION IN SOUTHERN CANADA. THE MAIN FEATURE TO NOTE IS A POTENT LOOKING SHRTWV IN NE ALBERTA. OVER UPPER MI...THE WEATHER HAS BEEN QUIET...THANKS TO LOW TO MID-LEVEL DRY AIR ROTATING AROUND A 1032MB HIGH SITUATED NEAR GEORGIAN BAY. THE LOW LEVEL AIR HAS NOT BEEN COMPLETELY DRY...THOUGH...AND THIS WAS EVIDENT BY A STRATUS DECK THAT HAS BEEN SLOWLY MIXING OUT OVER SOUTH CENTRAL UPPER MI. TAMDAR SOUNDINGS SHOWED A SHARP INVERSION FROM 900MB TO THE SFC...AND SE WINDS WERE ADVECTING MOISTURE OFF LAKE MICHIGAN UP THE MENOMINEE RIVER. ENOUGH DAYTIME HEATING HAS OCCURRED NOW TO MIX SOME OF THE DRIER AIR ABOVE 900MB TO THE SFC...ALLOWING THE CLOUDS TO BREAK UP. TO OUR SOUTH...DIURNAL CUMULUS CAN BE SEEN OVER EASTERN IA WHERE DEWPOINTS ARE IN THE LOW 60S. TO THE WEST...VERY WARM TEMPS ARE SEEN ACROSS THE DAKOTAS...WITH BISMARCK AT 90 AS OF 19Z. THE 850MB TEMP THERE AT 12Z WAS 20C...COMPARED TO 11C AT INL...2C AT PICKLE LAKE ONTARIO AND -9C AT MOOSONEE ONTARIO. WELL OFF TO THE NW ASSOCIATED WITH THE SHRTWV...A 1002MB LOW AS OVER FAR NRN MANITOBA...WITH A TROUGH EXTENDING DOWN THE LEE OF THE ROCKIES AND A COLD FRONT EXTENDING WEST THROUGH ALBERTA. IN YELLOWKNIFE...IT IS 41 F WITH -DZ AND A GUSTY NW WIND...A SIGN OF AIR TO COME FOR EARLY THIS WEEKEND. && .SHORT TERM (TONIGHT AND FRI)... SHRTWV TROUGH OVER NE ALBERTA WILL BE MOVING SOUTHEAST DURING THE NEXT 24 HOURS...REACHING FAR NW ONTARIO BY 00Z SAT. AS THIS OCCURS...IT WILL DRIVE THE COLD FRONT IN NORTHERN ALBERTA THROUGH MUCH OF NW ONTARIO...REACHING THUNDER BAY BY 00Z SAT. THEREFORE UPPER MICHIGAN IS GOING TO BE UNDER A WARM ADVECTION REGIME... BRINGING SOME OF THAT WARM AIR SEEN OVER IN BISMARCK EASTWARD ACROSS UPPER MI. 850MB TEMPS CLIMB FROM THE CURRENT 6-10C READINGS PER RUC ANALYSIS TO AROUND 14C FOR THE DAY FRIDAY. TONIGHT...TEMPERATURES SHOULD STRUGGLE FALLING MUCH WITH A BREEZY SW WIND...ESPECIALLY NEAR THE SHORELINES. WARMEST READINGS WILL BE IN THE WESTERN U.P. WHERE LOWS ARE NOT EXPECTED BELOW 60. THE QUESTION IS HOW MUCH DOES IT COOL DOWN A FEW THOUSAND FEET OFF THE SURFACE IN THE INTERIOR OVER NORTHERN WI AND WESTERN UPPER MI. THE REASON IS THAT THE SOUTHERLY WINDS WILL BRING UP THE UPPER 50S/LOW 60S DEWPOINTS OVER EASTERN IA. IF THE AIRMASS JUST ABOVE THE SURFACE COOLS DOWN...THEN A STRATUS DECK COULD FORM OVER NRN WI AND WESTERN UPPER MI. RH PROGS AT 925 AND 900MB FROM THE GFS...NAM AND OUR LOCAL WRF-ARW RUN REFLECT THAT IDEA BY SHOWING VALUES OF OVER 90 PCT. ON THE OTHER HAND...SW WINDS DO NOT SEEM TO DEVELOP STRATUS DECKS AS WELL HERE. THEREFORE...HAVE SPLIT THE DIFFERENCE BY GOING PARTLY CLOUDY...AND SHOWING THE POSSIBILITY IN THE SKY GRIDS WITH VALUES INCREASING SW TO NE AFTER 06Z. NO PCPN WORRIES OUT OF THIS SINCE WHATEVER DECK WOULD FORM SHOULD BE THIN. FRIDAY...ISENTROPIC LIFT SEEN ON THE 310K SFC...RELATED TO THE WARM ADVECTION AHEAD OF THE SHRTWV/COLD FRONT...SHOULD RESULT IN A DECK OF MID/HIGH CLOUDS MOVING NW TO SE ACROSS UPPER MI DURING THE DAY. ALL MODELS DEPICT SOME LIGHT PCPN OCCURRING OUT OF THESE MID CLOUDS (LIKELY AN ACCAS DECK). CANNOT RULE THIS OUT DUE TO TWO FEATURES COMING IN PLAY...A WEAK ZONE OF 700-600MB FRONTOGENESIS AND RIGHT ENTRANCE REGION FORCING WITH A 50-60KT JET MOVING NW TO SE ACROSS LAKE SUPERIOR. IN ADDITION...SOUNDINGS LIFTED FROM 700MB WHEN THE MID CLOUDS ARE PRESENT INDICATE A FEW HUNDRED J/KG OF CAPE...DUE TO THE ADVECTION OF 7.5-8C/KM LAPSE RATES ACROSS THE CWA. THEREFORE 20 POPS EXIST IN THE FORECAST WITH BOTH SHOWERS AND THUNDER MENTIONED. CLOUD COVER CREATES SOME CONCERN WITH MAX TEMPS...AND HAVE LOWERED HIGHS JUST A DEGREE TO ACCOUNT FOR THE POSSIBILITY OF THICKER CLOUD COVER THAT IS INDICATED BY MODELS. EITHER WAY...IT SHOULD BE WARM WITH RESPECT TO MID SEPTEMBER READINGS...BUT STILL BELOW RECORD HIGHS WHICH ARE IN THE LOW TO MID 80S. .LONG TERM (FRI NIGHT THROUGH NEXT THU)... CHANCES OF RAIN ARE THE MAIN CONCERN FRIDAY NIGHT. GFS AND NAM IN GOOD AGREEMENT WITH UPPER AIR AND MSLP PATTERNS THROUGH THE WEEKEND. FOLLOWED THE LOCAL WRF-ARW IN ITS DEPICTION OF BRINGING COLD FRONT THROUGH LATE IN THE EVENING INTO NORTHERN LK SUPERIOR AND ACROSS ALL CWA EXCEPT FAR SOUTH MENOMINEE COUNTY BY DAYBREAK SAT. GREATEST H85 MOISTURE ADVECTION WITH THE FRONT SHIFTS INTO EASTERN CWA EARLY EVENING SO KEPT THE POPS THERE. OTHERWISE...HAVE CLOUDS DECREASING EARLY IN THE EVENING THEN INCREASING AGAIN AFTER MIDNIGHT IN WAKE OF THE COLD FRONT. H85 TEMPS DROP TO +3C BY 12Z. SOUNDINGS SHOW MOISTENING BLO H85...LIKELY SOME LK EFFECT STRATOCUMULUS CLOUDS. KEPT THE SMALL POP IN THERE OVERNIGHT...BUT RESTRICTED IT TO JUST POTENTIAL LIGHT LK EFFECT PCPN. GIVEN UPSLOPE NORTHERLY FLOW AND TEMPS AT TOP OF INVERSION NOT WARMING...WILL PROBABLY TAKE A WHILE FOR THE LK EFFECT CLOUDS TO DISSIPATE ON SATURDAY. LOW LEVEL DRYING AND HIGH PRESSURE BUILDING IN/PWAT MIN TO ENHANCE RADIATIONAL COOLING SHOULD LEAD TO CLEAR AND CALM NIGHT SATURDAY NIGHT. LOWERED GOING MINS INTO THE LWR-MID 30S TOWARD COOP MOS GUIDANCE. UPPER LEVEL TROUGH/COOLER TEMPS AROUND FOR THE WEEKEND EASES INTO EASTERN CANADA BY NEXT MON WHILE RIDGE/WARM AIR OVER SOUTHERN UNITED STATES BUILDS TOWARD GREAT LAKES. RIDGE QUITE STRONG...WITH HEIGHTS NEARING 590DAM TUE INTO WED. WARM FRONT LIFTS THROUGH UPPER MI/LAKE SUPERIOR SUN NIGHT. CONCENTRATED MOISTURE ADVECTION REMAINS NORTH AND WEST OF UPPER MICHIGAN SO ANY POPS SHOULD BE CONFINED TO LAKE SUPERIOR. SFC RIDGE IS CLOSE ENOUGH ON MON AND PERHAPS TUE AS WELL TO KEEP BLYR WINDS MAINLY FM THE SOUTH WHICH IS NOT IDEAL FOR WARMING UP TOO MUCH. STILL...GIVEN H85 TEMPS ARE WARMING ABOVE +10C EXPECT AREAS AWAY FM LAKE MICHIGAN TO HAVE HIGH TEMPS INTO THE MID-UPR 70S AND COULD EVEN SEE LWR 80S OVR WEST CWA. COLD FRONT STILL ON TRACK TO MOVE THROUGH ON WED-THU. FOLLOWED ECMWF...UKMET... AND CANADIAN IDEA WITH A SLOWER FROPA THAN GFS SHOWED. INTERESTING NOW THOUGH THAT THE 12Z GFS/ECMWF FLIPPED WITH THE GFS SLOWER AND THE ECMWF MORE PROGRESSIVE. CHANGES TO POPS WERE MINIMAL AND ESSENTIALLY KEPT THE HIGHEST POPS OVR THE WEST WEDNESDAY AND ACROSS REST OF THE AREA WEDNESDAY NIGHT AND THURSDAY. DEPENDING ON CLOUD COVER FOR WED...HIGH TEMPS MAY REACH WELL INTO THE 70S AND POSSIBLY LWR 80S AGAIN AS WINDS BECOME SW AHEAD OF THE COLD FRONT. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... VFR CONDITIONS TO PREVAIL OVER BOTH TAF SITES THROUGH 0Z SATURDAY. LLWS CONDITIONS EXPECTED OVER BOTH SITES AS WINDS INCREASE OVERNIGHT ABOVE THE BOUNDARY LAYER. ONCE EARLY MORNING SUNSHINE KICKS IN...WINDS SHOULD MIX DOWN AND CREATE GUSTY CONDITIONS FRI UNTIL GRADIENT RELAXES LATE IN THE FORECAST. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... TIGHT PRESSURE GRADIENT WILL EXIST OVER LAKE SUPERIOR TONIGHT AND FRIDAY AS A COLD FRONT OVER NORTH CENTRAL CANADA DROPS DOWN TO THUNDER BAY ONTARIO BY FRIDAY EVENING. EXPECT SOUTHWEST WINDS TO INCREASE TO 30 KNOTS THIS EVENING...WITH FREQUENT GALE FORCE GUSTS OVER EASTERN LAKE SUPERIOR LATE TONIGHT THROUGH FRIDAY MORNING. A FEW GALE FORCE GUSTS ARE ALSO POSSIBLE ON WEST AND NORTH CENTRAL LAKE SUPERIOR. AS THE FRONT NEARS...WINDS WILL SLOWLY DECREASE. THE DECREASE IN WINDS WILL BE SHORT LIVED AS ANOTHER POTENTIAL GALE DEVELOPS LATER FRIDAY EVENING...THIS TIME BEHIND THE FRONT DUE TO STRONG COLD AIR ADVECTION. NORTHERLY GALES WILL BE RELATIVELY BRIEF AND SHOULD END BY SUNRISE SATURDAY AS HIGH PRESSURE MOVES INTO THE REGION. WINDS LESS THAN 20 KNOTS ON INTO SUNDAY AS THE HIGH PRESSURE RIDGE CONTINUES TO DRIFT ACROSS. SOUTH WINDS INCREASE ON BACK SIDE OF THIS HIGH BY EARLY NEXT WEEK WITH WINDS UP TO 30 KNOTS STARTING UP AS EARLY AS NEXT TUESDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... GALE WARNING FROM 4 AM TO 12 PM EDT FRIDAY FOR LSZ266-267. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/SHORT TERM...AJ LONG TERM...JLA AVIATION...RJT MARINE...AJ/JLA mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 152 PM EDT THU SEP 18 2008 UPDATED AVIATION DISCUSSION FOR 18Z TAF ISSUANCE .SYNOPSIS... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A BROAD RIDGE CENTERED OVER FAR WRN NAMERICA WITH A BROAD TROF OVER THE CNTRL/E...ANCHORED BY THE POLAR VORTEX CENTERED OVER NRN HUDSON BAY. AS A RESULT...NW FLOW IS OVER THE UPPER GREAT LAKES EARLY THIS MORNING. NEXT SHORTWAVES OF REAL INTEREST ARE OVER THE SE YUKON AND THE WRN NW TERRITORIES. THESE SHORTWAVES WILL DIVE SE INTO THE CNTRL/ERN NAMERICA TROF OVER THE NEXT COUPLE OF DAYS. CLOSER TO HOME...SFC HIGH PRES WAS CENTERED JUST NE OF LAKE SUPERIOR EARLY THIS MORNING. STRATOCU HAS DEVELOPED NEAR LAKE SUPERIOR DURING THE NIGHT AS AIRMASS IS JUST COLD ENOUGH FOR LAKE EFFECT CLOUDS. IN ADDITION... PATCHY FOG/STRATUS HAS ALSO BEEN FORMING IN THE INTERIOR. AS RESULT...TEMPS HAVE BEEN FLUCTUATING WIDELY AND VARY QUITE A BIT ACROSS THE FCST AREA. A NUMBER OF OBS SITES ACROSS THE INTERIOR CNTRL AND ERN FCST AREA HAVE STILL MANAGED TO FALL INTO THE 30S AS OF 08Z WITH SPINCICH LAKE THE COLDEST AT 32F. TO THE W...WAA REGIME ON BACKSIDE OF THE HIGH IS SUPPORTING MID CLOUDS OVER NE ND/NRN MN WITH RADARS SHOWING SOME NARROW BANDS OF RETURNS AND POSSIBLE -SHRA/SPRINKLES. && .DISCUSSION... WITH A NUMBER OF OBS SITES SHOWING TEMPS IN THE MID/UPPER 30S ACROSS THE FROST ADVY AREA...WILL LET FROST ADVY RUN THRU EXPIRATION TIME OF 12Z. OTHERWISE...RETURN FLOW WILL SET UP TODAY AS HIGH PRES SLIPS TO THE ESE. WARMING WILL BE MOST APPARENT OVER THE W WHERE 850MB TEMPS CLIMB TO 10-12C BY 18Z (STILL 5-6C OUT E). MIXING TO 850MB YIELDS HIGH TEMPS IN THE LWR 70S W TO MID 60S E WHICH IS INLINE WITH AVBL 00Z MOS GUIDANCE. AS FOR CLOUD COVER...PATCHY FOG/STRATUS WILL QUICKLY DISSIPATE AFTER SUNRISE AND STRATOCU NEAR THE LAKE SHOULD ALSO DISSIPATE OR AT LEAST MOVE OFFSHORE DURING THE MORNING AS AIRMASS WARMS AND WINDS IN THE CLOUD LAYER BACK SRLY. STRONGEST WAA CURRENTLY FOCUSED TO THE W AND NW OF UPPER MI SURGES NE DURING THE DAY TODAY. AS A RESULT...MID CLOUDS BEING PRODUCED BY THE WAA/ISENTROPIC ASCENT SHOULD ALSO SHIFT MOSTLY TO THE NE. A FEW DISSIPATING REMNANTS PEELING SE WILL PROBABLY BE THE ONLY CLOUD COVER HERE TODAY ONCE MORNING CLOUDS DEPART. SO...A GENERALLY MOSTLY SUNNY DAY IS ANTICIPATED. TONIGHT AND FRI...PAIR OF SHORTWAVES CURRENTLY OVER NW CANADA WILL HEAD SE THEN E ACROSS SRN CANADA. ASSOCIATED STRENGTHENING SFC LOW OVER SASKATCHEWAN THIS EVENING WILL MOVE E...REACHING SRN HUDSON BAY FRI AFTN. SW FLOW AHEAD OF THE LOW WILL DRAW UNSEASONABLY WARM AIR INTO THE UPPER LAKES REGION TONIGHT/FRI. WITH STRENGTHENING LOW-LEVEL JET...ALWAYS NEED TO CONSIDER THE POTENTIAL OF ELEVATED CONVECTION. HOWEVER...WITH NOSE OF LOW-LEVEL JET/STRONGEST FLOW PASSING TO THE N OF UPPER MI TONIGHT...POTENTIAL OF CONVECTION HERE STILL LOOKS MINIMAL. NAM FCST SOUNDINGS DO SHOW A SMALL WINDOW WHERE THERE MAY BE ENOUGH MOISTURE AROUND THE TOP OF THE INVERSION TO PROVIDE CAPE OF SEVERAL HUNDRED J/KG FOR PARCELS LIFTED FROM ABOVE THE SFC BASED INVERSION. GFS FCST SOUNDINGS SHOW SIMILAR MOISTENING...BUT WITH CAPE ONLY A LITTLE LESS THAN THE NAM. SO...A LITTLE CONCERNED THAT ISOLD SHRA/TSRA COULD DEVELOP...BUT SINCE LOW-LEVEL JET IS FOCUSED N OF THE FCST AREA...WILL CONTINUE TO RIDE WITH A DRY FCST OVER ALL BUT NRN LAKE SUPERIOR TONIGHT. INCREASING SW WINDS TONIGHT WILL RESULT IN MIN TEMPS CONSIDERABLY HIGHER THAN THIS MORNING...ESPECIALLY ACROSS THE W AND N WHERE WINDS WILL BE LEAST DECOUPLED. GFS/ETA MOS OF AROUND 60F FOR A MIN TEMP AT KIWD STILL LOOKS ON TRACK. MID/UPPER 50S SHOULD BE COMMON ELSEWHERE FROM THE W INTO THE NCNTRL NEAR LAKE SUPERIOR. READINGS SHOULD TREND DOWN TO AROUND 50F SCNTRL AND E WHERE WINDS WILL BE LIGHTER. AS SFC LOW PRES HEADS FOR SRN HUDSON BAY FRI...ASSOCIATED COLD FRONT WILL DROP SE TOWARD LAKE SUPERIOR. THIS WILL PROVIDE NEARLY AN IDEAL SETUP FOR WARMTH AS AXIS OF 850MB THERMAL RIDGE ALMOST REACHES UPPER MI EARLY FRI AFTN AHEAD OF THE FRONT. WITH SW WINDS AND 850MB TEMPS RISING TO AROUND 14C...TEMPS SHOULD HAVE NO TROUBLE RISING WELL INTO THE MID AND UPPER 70S OVER THE W AND CNTRL...WARMEST IN THE DOWNSLOPE AREAS. WOULD NOT BE SURPRISED TO SEE A FEW 80F READINGS. FLOW WILL BE BACKED ENOUGH OFF LAKE MICHIGAN FOR LWR TEMPS (UPPER 60S/LWR 70S) DOWNWIND INTO THE FAR ERN FCST AREA. WINDS IN THE MIXED LAYER SHOULD SUPPORT GUSTS IN THE 30-35 MPH RANGE IN MANY LOCATIONS FRI. AS FOR PCPN CHC...AIRMASS WILL PROBABLY BE CAPPED FRI... ESPECIALLY SINCE MODELS MAY BE A COUPLE OF DEGREES TOO HIGH ON SFC DWPTS. HOWEVER...THERE IS STILL ENOUGH UNCERTAINTY TO MAINTAIN THE INHERITED FCST OF JUST 20 POPS OVER THE WRN PORTION OF THE FCST AREA...CLOSER TO APPROACHING COLD FRONT. COLD FRONT WILL DROP S THRU THE FCST AREA FRI NIGHT. WITH LOSS OF DAYTIME HEATING AND ONLY WEAK DEEP LAYER FORCING...THERE IS NO NEED TO GO ANY HIGHER THAN SLIGHT CHC POPS WITH FROPA. WILL CARRY SLIGHT CHC POPS INTO EARLY SAT MORNING OVER THE FAR SCNTRL FCST AREA. OTHERWISE...HIGH PRES WILL BEGIN TO BUILD SE TOWARD THE UPPER GREAT LAKES...PROVIDING A DRY/COOLER DAY SAT. TEMPS SHOULD TOP OUT IN THE LWR 60S N TO UPPER 60S S. EXPECT DRY WX TO CONTINUE SUN/MON AS MID-LEVEL RIDGE FROM THE NRN PLAINS BUILDS BACK OVER THE AREA. LOOK FOR HIGH TEMPS TO REBOUND INTO THE UPPER 60S/LWR 70S FOR MON. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... MOST OF THE NEXT 24 HOURS AT BOTH TAF SITES ARE EXPECTED TO BE VFR...THANKS TO A DRY SOUTHEAST FLOW JUST ABOVE THE SFC COMING OUT OF HIGH PRESSURE MOVING SE OVER ONTARIO. THERE ARE A FEW PROBLEMS TO CONTEND WITH...THOUGH. LURKING TO THE SOUTH OF SAW ARE MVFR CLOUDS ACROSS DICKINSON/MENOMINEE AND DELTA COUNTIES. THESE HAVE PERSISTED THANKS TO SE FLOW OFF LAKE MI BRINGING MOISTURE UNDERNEATH WARM AIR SPREADING IN ALOFT. HOWEVER...SUNSHINE IS STARTING TO MIX THESE OUT...SO DO NOT THINK THEY WILL BE IMPACTING SAW...DESPITE WINDS TRYING TO ADVECT THEM IN. TONIGHT...SW WINDS WILL BRING MORE MOISTURE INTO UPPER MI FROM IA/NRN IL. THERE IS A CHANCE THAT AN IFR OR MVFR STRATUS DECK COULD FORM OVER NRN WI AFTER MIDNIGHT AND MOVE INTO SAW TOWARDS SUNRISE...AND NOT MIX OUT UNTIL LATE MORNING. HOWEVER...CONFIDENCE IS TOO LOW TO MENTION IFR OR MVFR CIGS AT THIS TIME. THE THIRD PROBLEM IS LLWS...WHICH BOTH TAF SITES SHOULD EXPERIENCE TONIGHT BEFORE DAYTIME HEATING MIXES IT OUT AND CAUSES WINDS TO BECOME GUSTY. && .MARINE (FOR THE 10 AM LAKE SUPERIOR FORECAST ISSUANCE)... 10 AM UPDATE...CONDITIONS CONTINUE TO LOOK FAVORABLE FOR GALE FORCE WINDS ON EASTERN LAKE SUPERIOR LATE TONIGHT/FRIDAY MORNING. THEREFORE HAVE WENT AHEAD AND ISSUED THE GALE WARNING FOR LSZ266-267. DROPPED THE GALE WATCH FOR 264 AS RIGHT NOW CONDITIONS DO NOT APPEAR AS FAVORABLE...THOUGH STILL MENTIONED A FEW GALE FORCE GUSTS. AS THE HIGH CENTER MOVES EAST TODAY AND TONIGHT AND LOW PRESSURE ACROSS NORTHERN ONTARIO FOLLOWS...THERE WILL BE A STRENGTHENING OF SOUTHERLY FLOW. FREQUENT 35KT GUSTS MAY OCCUR ON CENTRAL AND EASTERN LAKE SUPERIOR LATE TONIGHT INTO FRIDAY MORNING. A COLD FRONT WILL MOVE ACROSS LAKE SUPERIOR LATE FRIDAY NIGHT AND SATURDAY MORNING CAUSING WINDS TO SHIFT NORTH AND NORTHWEST ON SATURDAY. AS HIGH PRESSURE OVER MANITOBA NOSES SOUTHEASTWARD OVER ONTARIO LATE SATURDAY THROUGH SUNDAY...WINDS WILL REMAIN LESS THAN 20 KTS. AS THE RIDGE SHIFTS INTO QUEBEC ON MONDAY AND LOW PRESSURE DEVELOPS ACROSS THE ROCKIES...THERE WILL BE A STRENGTHENING OF SOUTHERLY WINDS AGAIN. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... GALE WARNING FROM 4 AM TO 12 PM EDT FRIDAY FOR LSZ266-267. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...ROLFSON AVIATION...AJ MARINE...DLG/AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1035 AM EDT THU SEP 18 2008 UPDATED MARINE AND WATCH/WARNING/ADVISORY SECTIONS FOR GALE WARNING. .SYNOPSIS... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A BROAD RIDGE CENTERED OVER FAR WRN NAMERICA WITH A BROAD TROF OVER THE CNTRL/E...ANCHORED BY THE POLAR VORTEX CENTERED OVER NRN HUDSON BAY. AS A RESULT...NW FLOW IS OVER THE UPPER GREAT LAKES EARLY THIS MORNING. NEXT SHORTWAVES OF REAL INTEREST ARE OVER THE SE YUKON AND THE WRN NW TERRITORIES. THESE SHORTWAVES WILL DIVE SE INTO THE CNTRL/ERN NAMERICA TROF OVER THE NEXT COUPLE OF DAYS. CLOSER TO HOME...SFC HIGH PRES WAS CENTERED JUST NE OF LAKE SUPERIOR EARLY THIS MORNING. STRATOCU HAS DEVELOPED NEAR LAKE SUPERIOR DURING THE NIGHT AS AIRMASS IS JUST COLD ENOUGH FOR LAKE EFFECT CLOUDS. IN ADDITION... PATCHY FOG/STRATUS HAS ALSO BEEN FORMING IN THE INTERIOR. AS RESULT...TEMPS HAVE BEEN FLUCTUATING WIDELY AND VARY QUITE A BIT ACROSS THE FCST AREA. A NUMBER OF OBS SITES ACROSS THE INTERIOR CNTRL AND ERN FCST AREA HAVE STILL MANAGED TO FALL INTO THE 30S AS OF 08Z WITH SPINCICH LAKE THE COLDEST AT 32F. TO THE W...WAA REGIME ON BACKSIDE OF THE HIGH IS SUPPORTING MID CLOUDS OVER NE ND/NRN MN WITH RADARS SHOWING SOME NARROW BANDS OF RETURNS AND POSSIBLE -SHRA/SPRINKLES. && .DISCUSSION... WITH A NUMBER OF OBS SITES SHOWING TEMPS IN THE MID/UPPER 30S ACROSS THE FROST ADVY AREA...WILL LET FROST ADVY RUN THRU EXPIRATION TIME OF 12Z. OTHERWISE...RETURN FLOW WILL SET UP TODAY AS HIGH PRES SLIPS TO THE ESE. WARMING WILL BE MOST APPARENT OVER THE W WHERE 850MB TEMPS CLIMB TO 10-12C BY 18Z (STILL 5-6C OUT E). MIXING TO 850MB YIELDS HIGH TEMPS IN THE LWR 70S W TO MID 60S E WHICH IS INLINE WITH AVBL 00Z MOS GUIDANCE. AS FOR CLOUD COVER...PATCHY FOG/STRATUS WILL QUICKLY DISSIPATE AFTER SUNRISE AND STRATOCU NEAR THE LAKE SHOULD ALSO DISSIPATE OR AT LEAST MOVE OFFSHORE DURING THE MORNING AS AIRMASS WARMS AND WINDS IN THE CLOUD LAYER BACK SRLY. STRONGEST WAA CURRENTLY FOCUSED TO THE W AND NW OF UPPER MI SURGES NE DURING THE DAY TODAY. AS A RESULT...MID CLOUDS BEING PRODUCED BY THE WAA/ISENTROPIC ASCENT SHOULD ALSO SHIFT MOSTLY TO THE NE. A FEW DISSIPATING REMNANTS PEELING SE WILL PROBABLY BE THE ONLY CLOUD COVER HERE TODAY ONCE MORNING CLOUDS DEPART. SO...A GENERALLY MOSTLY SUNNY DAY IS ANTICIPATED. TONIGHT AND FRI...PAIR OF SHORTWAVES CURRENTLY OVER NW CANADA WILL HEAD SE THEN E ACROSS SRN CANADA. ASSOCIATED STRENGTHENING SFC LOW OVER SASKATCHEWAN THIS EVENING WILL MOVE E...REACHING SRN HUDSON BAY FRI AFTN. SW FLOW AHEAD OF THE LOW WILL DRAW UNSEASONABLY WARM AIR INTO THE UPPER LAKES REGION TONIGHT/FRI. WITH STRENGTHENING LOW-LEVEL JET...ALWAYS NEED TO CONSIDER THE POTENTIAL OF ELEVATED CONVECTION. HOWEVER...WITH NOSE OF LOW-LEVEL JET/STRONGEST FLOW PASSING TO THE N OF UPPER MI TONIGHT...POTENTIAL OF CONVECTION HERE STILL LOOKS MINIMAL. NAM FCST SOUNDINGS DO SHOW A SMALL WINDOW WHERE THERE MAY BE ENOUGH MOISTURE AROUND THE TOP OF THE INVERSION TO PROVIDE CAPE OF SEVERAL HUNDRED J/KG FOR PARCELS LIFTED FROM ABOVE THE SFC BASED INVERSION. GFS FCST SOUNDINGS SHOW SIMILAR MOISTENING...BUT WITH CAPE ONLY A LITTLE LESS THAN THE NAM. SO...A LITTLE CONCERNED THAT ISOLD SHRA/TSRA COULD DEVELOP...BUT SINCE LOW-LEVEL JET IS FOCUSED N OF THE FCST AREA...WILL CONTINUE TO RIDE WITH A DRY FCST OVER ALL BUT NRN LAKE SUPERIOR TONIGHT. INCREASING SW WINDS TONIGHT WILL RESULT IN MIN TEMPS CONSIDERABLY HIGHER THAN THIS MORNING...ESPECIALLY ACROSS THE W AND N WHERE WINDS WILL BE LEAST DECOUPLED. GFS/ETA MOS OF AROUND 60F FOR A MIN TEMP AT KIWD STILL LOOKS ON TRACK. MID/UPPER 50S SHOULD BE COMMON ELSEWHERE FROM THE W INTO THE NCNTRL NEAR LAKE SUPERIOR. READINGS SHOULD TREND DOWN TO AROUND 50F SCNTRL AND E WHERE WINDS WILL BE LIGHTER. AS SFC LOW PRES HEADS FOR SRN HUDSON BAY FRI...ASSOCIATED COLD FRONT WILL DROP SE TOWARD LAKE SUPERIOR. THIS WILL PROVIDE NEARLY AN IDEAL SETUP FOR WARMTH AS AXIS OF 850MB THERMAL RIDGE ALMOST REACHES UPPER MI EARLY FRI AFTN AHEAD OF THE FRONT. WITH SW WINDS AND 850MB TEMPS RISING TO AROUND 14C...TEMPS SHOULD HAVE NO TROUBLE RISING WELL INTO THE MID AND UPPER 70S OVER THE W AND CNTRL...WARMEST IN THE DOWNSLOPE AREAS. WOULD NOT BE SURPRISED TO SEE A FEW 80F READINGS. FLOW WILL BE BACKED ENOUGH OFF LAKE MICHIGAN FOR LWR TEMPS (UPPER 60S/LWR 70S) DOWNWIND INTO THE FAR ERN FCST AREA. WINDS IN THE MIXED LAYER SHOULD SUPPORT GUSTS IN THE 30-35 MPH RANGE IN MANY LOCATIONS FRI. AS FOR PCPN CHC...AIRMASS WILL PROBABLY BE CAPPED FRI... ESPECIALLY SINCE MODELS MAY BE A COUPLE OF DEGREES TOO HIGH ON SFC DWPTS. HOWEVER...THERE IS STILL ENOUGH UNCERTAINTY TO MAINTAIN THE INHERITED FCST OF JUST 20 POPS OVER THE WRN PORTION OF THE FCST AREA...CLOSER TO APPROACHING COLD FRONT. COLD FRONT WILL DROP S THRU THE FCST AREA FRI NIGHT. WITH LOSS OF DAYTIME HEATING AND ONLY WEAK DEEP LAYER FORCING...THERE IS NO NEED TO GO ANY HIGHER THAN SLIGHT CHC POPS WITH FROPA. WILL CARRY SLIGHT CHC POPS INTO EARLY SAT MORNING OVER THE FAR SCNTRL FCST AREA. OTHERWISE...HIGH PRES WILL BEGIN TO BUILD SE TOWARD THE UPPER GREAT LAKES...PROVIDING A DRY/COOLER DAY SAT. TEMPS SHOULD TOP OUT IN THE LWR 60S N TO UPPER 60S S. EXPECT DRY WX TO CONTINUE SUN/MON AS MID-LEVEL RIDGE FROM THE NRN PLAINS BUILDS BACK OVER THE AREA. LOOK FOR HIGH TEMPS TO REBOUND INTO THE UPPER 60S/LWR 70S FOR MON. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... IR SATELLITE AND OBSERVATIONS SHOWING LOW CLOUDS EXTENDING FROM KCMX TO KSAW. KSAW REPORTING PERIODS OF LIFR CONDITIONS. BY 14Z VFR CONDITIONS WILL PREVAIL THROUGH THE REST OF THIS FORECAST PERIOD WITH DRY HIGH PRESSURE OVER THE GREAT LAKES TODAY. LIGHT WINDS BECOMING SOUTHERLY THIS AFTERNOON AS THE HIGH SHIFTS EAST OF UPPER MICHIGAN. STRENGTHENING SOUTHERLY FLOW BETWEEN THIS DEPARTING HIGH AND THE LOW PRESSURE IN SOUTH CENTRAL CANADA ABOVE DEVELOPING RADIATION INVERSION WILL RESULT IN LLWS AT BOTH SITES AFT 00Z FRIDAY. && .MARINE (FOR THE 10 AM LAKE SUPERIOR FORECAST ISSUANCE)... 10 AM UPDATE...CONDITIONS CONTINUE TO LOOK FAVORABLE FOR GALE FORCE WINDS ON EASTERN LAKE SUPERIOR LATE TONIGHT/FRIDAY MORNING. THEREFORE HAVE WENT AHEAD AND ISSUED THE GALE WARNING FOR LSZ266-267. DROPPED THE GALE WATCH FOR 264 AS RIGHT NOW CONDITIONS DO NOT APPEAR AS FAVORABLE...THOUGH STILL MENTIONED A FEW GALE FORCE GUSTS. AS THE HIGH CENTER MOVES EAST TODAY AND TONIGHT AND LOW PRESSURE ACROSS NORTHERN ONTARIO FOLLOWS...THERE WILL BE A STRENGTHENING OF SOUTHERLY FLOW. FREQUENT 35KT GUSTS MAY OCCUR ON CENTRAL AND EASTERN LAKE SUPERIOR LATE TONIGHT INTO FRIDAY MORNING. A COLD FRONT WILL MOVE ACROSS LAKE SUPERIOR LATE FRIDAY NIGHT AND SATURDAY MORNING CAUSING WINDS TO SHIFT NORTH AND NORTHWEST ON SATURDAY. AS HIGH PRESSURE OVER MANITOBA NOSES SOUTHEASTWARD OVER ONTARIO LATE SATURDAY THROUGH SUNDAY...WINDS WILL REMAIN LESS THAN 20 KTS. AS THE RIDGE SHIFTS INTO QUEBEC ON MONDAY AND LOW PRESSURE DEVELOPS ACROSS THE ROCKIES...THERE WILL BE A STRENGTHENING OF SOUTHERLY WINDS AGAIN. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...NONE. LAKE SUPERIOR... GALE WARNING FROM 4 AM TO 12 PM EDT FRIDAY FOR LSZ266-267. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...ROLFSON AVIATION...KC MARINE...DLG/AJ mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 731 AM EDT THU SEP 18 2008 .SYNOPSIS... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A BROAD RIDGE CENTERED OVER FAR WRN NAMERICA WITH A BROAD TROF OVER THE CNTRL/E...ANCHORED BY THE POLAR VORTEX CENTERED OVER NRN HUDSON BAY. AS A RESULT...NW FLOW IS OVER THE UPPER GREAT LAKES EARLY THIS MORNING. NEXT SHORTWAVES OF REAL INTEREST ARE OVER THE SE YUKON AND THE WRN NW TERRITORIES. THESE SHORTWAVES WILL DIVE SE INTO THE CNTRL/ERN NAMERICA TROF OVER THE NEXT COUPLE OF DAYS. CLOSER TO HOME...SFC HIGH PRES WAS CENTERED JUST NE OF LAKE SUPERIOR EARLY THIS MORNING. STRATOCU HAS DEVELOPED NEAR LAKE SUPERIOR DURING THE NIGHT AS AIRMASS IS JUST COLD ENOUGH FOR LAKE EFFECT CLOUDS. IN ADDITION... PATCHY FOG/STRATUS HAS ALSO BEEN FORMING IN THE INTERIOR. AS RESULT...TEMPS HAVE BEEN FLUCTUATING WIDELY AND VARY QUITE A BIT ACROSS THE FCST AREA. A NUMBER OF OBS SITES ACROSS THE INTERIOR CNTRL AND ERN FCST AREA HAVE STILL MANAGED TO FALL INTO THE 30S AS OF 08Z WITH SPINCICH LAKE THE COLDEST AT 32F. TO THE W...WAA REGIME ON BACKSIDE OF THE HIGH IS SUPPORTING MID CLOUDS OVER NE ND/NRN MN WITH RADARS SHOWING SOME NARROW BANDS OF RETURNS AND POSSIBLE -SHRA/SPRINKLES. && .DISCUSSION... WITH A NUMBER OF OBS SITES SHOWING TEMPS IN THE MID/UPPER 30S ACROSS THE FROST ADVY AREA...WILL LET FROST ADVY RUN THRU EXPIRATION TIME OF 12Z. OTHERWISE...RETURN FLOW WILL SET UP TODAY AS HIGH PRES SLIPS TO THE ESE. WARMING WILL BE MOST APPARENT OVER THE W WHERE 850MB TEMPS CLIMB TO 10-12C BY 18Z (STILL 5-6C OUT E). MIXING TO 850MB YIELDS HIGH TEMPS IN THE LWR 70S W TO MID 60S E WHICH IS INLINE WITH AVBL 00Z MOS GUIDANCE. AS FOR CLOUD COVER...PATCHY FOG/STRATUS WILL QUICKLY DISSIPATE AFTER SUNRISE AND STRATOCU NEAR THE LAKE SHOULD ALSO DISSIPATE OR AT LEAST MOVE OFFSHORE DURING THE MORNING AS AIRMASS WARMS AND WINDS IN THE CLOUD LAYER BACK SRLY. STRONGEST WAA CURRENTLY FOCUSED TO THE W AND NW OF UPPER MI SURGES NE DURING THE DAY TODAY. AS A RESULT...MID CLOUDS BEING PRODUCED BY THE WAA/ISENTROPIC ASCENT SHOULD ALSO SHIFT MOSTLY TO THE NE. A FEW DISSIPATING REMNANTS PEELING SE WILL PROBABLY BE THE ONLY CLOUD COVER HERE TODAY ONCE MORNING CLOUDS DEPART. SO...A GENERALLY MOSTLY SUNNY DAY IS ANTICIPATED. TONIGHT AND FRI...PAIR OF SHORTWAVES CURRENTLY OVER NW CANADA WILL HEAD SE THEN E ACROSS SRN CANADA. ASSOCIATED STRENGTHENING SFC LOW OVER SASKATCHEWAN THIS EVENING WILL MOVE E...REACHING SRN HUDSON BAY FRI AFTN. SW FLOW AHEAD OF THE LOW WILL DRAW UNSEASONABLY WARM AIR INTO THE UPPER LAKES REGION TONIGHT/FRI. WITH STRENGTHENING LOW-LEVEL JET...ALWAYS NEED TO CONSIDER THE POTENTIAL OF ELEVATED CONVECTION. HOWEVER...WITH NOSE OF LOW-LEVEL JET/STRONGEST FLOW PASSING TO THE N OF UPPER MI TONIGHT...POTENTIAL OF CONVECTION HERE STILL LOOKS MINIMAL. NAM FCST SOUNDINGS DO SHOW A SMALL WINDOW WHERE THERE MAY BE ENOUGH MOISTURE AROUND THE TOP OF THE INVERSION TO PROVIDE CAPE OF SEVERAL HUNDRED J/KG FOR PARCELS LIFTED FROM ABOVE THE SFC BASED INVERSION. GFS FCST SOUNDINGS SHOW SIMILAR MOISTENING...BUT WITH CAPE ONLY A LITTLE LESS THAN THE NAM. SO...A LITTLE CONCERNED THAT ISOLD SHRA/TSRA COULD DEVELOP...BUT SINCE LOW-LEVEL JET IS FOCUSED N OF THE FCST AREA...WILL CONTINUE TO RIDE WITH A DRY FCST OVER ALL BUT NRN LAKE SUPERIOR TONIGHT. INCREASING SW WINDS TONIGHT WILL RESULT IN MIN TEMPS CONSIDERABLY HIGHER THAN THIS MORNING...ESPECIALLY ACROSS THE W AND N WHERE WINDS WILL BE LEAST DECOUPLED. GFS/ETA MOS OF AROUND 60F FOR A MIN TEMP AT KIWD STILL LOOKS ON TRACK. MID/UPPER 50S SHOULD BE COMMON ELSEWHERE FROM THE W INTO THE NCNTRL NEAR LAKE SUPERIOR. READINGS SHOULD TREND DOWN TO AROUND 50F SCNTRL AND E WHERE WINDS WILL BE LIGHTER. AS SFC LOW PRES HEADS FOR SRN HUDSON BAY FRI...ASSOCIATED COLD FRONT WILL DROP SE TOWARD LAKE SUPERIOR. THIS WILL PROVIDE NEARLY AN IDEAL SETUP FOR WARMTH AS AXIS OF 850MB THERMAL RIDGE ALMOST REACHES UPPER MI EARLY FRI AFTN AHEAD OF THE FRONT. WITH SW WINDS AND 850MB TEMPS RISING TO AROUND 14C...TEMPS SHOULD HAVE NO TROUBLE RISING WELL INTO THE MID AND UPPER 70S OVER THE W AND CNTRL...WARMEST IN THE DOWNSLOPE AREAS. WOULD NOT BE SURPRISED TO SEE A FEW 80F READINGS. FLOW WILL BE BACKED ENOUGH OFF LAKE MICHIGAN FOR LWR TEMPS (UPPER 60S/LWR 70S) DOWNWIND INTO THE FAR ERN FCST AREA. WINDS IN THE MIXED LAYER SHOULD SUPPORT GUSTS IN THE 30-35 MPH RANGE IN MANY LOCATIONS FRI. AS FOR PCPN CHC...AIRMASS WILL PROBABLY BE CAPPED FRI... ESPECIALLY SINCE MODELS MAY BE A COUPLE OF DEGREES TOO HIGH ON SFC DWPTS. HOWEVER...THERE IS STILL ENOUGH UNCERTAINTY TO MAINTAIN THE INHERITED FCST OF JUST 20 POPS OVER THE WRN PORTION OF THE FCST AREA...CLOSER TO APPROACHING COLD FRONT. COLD FRONT WILL DROP S THRU THE FCST AREA FRI NIGHT. WITH LOSS OF DAYTIME HEATING AND ONLY WEAK DEEP LAYER FORCING...THERE IS NO NEED TO GO ANY HIGHER THAN SLIGHT CHC POPS WITH FROPA. WILL CARRY SLIGHT CHC POPS INTO EARLY SAT MORNING OVER THE FAR SCNTRL FCST AREA. OTHERWISE...HIGH PRES WILL BEGIN TO BUILD SE TOWARD THE UPPER GREAT LAKES...PROVIDING A DRY/COOLER DAY SAT. TEMPS SHOULD TOP OUT IN THE LWR 60S N TO UPPER 60S S. EXPECT DRY WX TO CONTINUE SUN/MON AS MID-LEVEL RIDGE FROM THE NRN PLAINS BUILDS BACK OVER THE AREA. LOOK FOR HIGH TEMPS TO REBOUND INTO THE UPPER 60S/LWR 70S FOR MON. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... IR SATELLITE AND OBSERVATIONS SHOWING LOW CLOUDS EXTENDING FROM KCMX TO KSAW. KSAW REPORTING PERIODS OF LIFR CONDITIONS. BY 14Z VFR CONDITIONS WILL PREVAIL THROUGH THE REST OF THIS FORECAST PERIOD WITH DRY HIGH PRESSURE OVER THE GREAT LAKES TODAY. LIGHT WINDS BECOMING SOUTHERLY THIS AFTERNOON AS THE HIGH SHIFTS EAST OF UPPER MICHIGAN. STRENGTHENING SOUTHERLY FLOW BETWEEN THIS DEPARTING HIGH AND THE LOW PRESSURE IN SOUTH CENTRAL CANADA ABOVE DEVELOPING RADIATION INVERSION WILL RESULT IN LLWS AT BOTH SITES AFT 00Z FRIDAY. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... AS THE HIGH CENTER MOVES EAST TODAY AND TONIGHT AND LOW PRESSURE ACROSS NORTHERN ONTARIO FOLLOWS...THERE WILL BE A STRENGTHENING OF SOUTHERLY FLOW. FREQUENT 35KT GUSTS MAY OCCUR ON CENTRAL AND EASTERN LAKE SUPERIOR LATE TONIGHT INTO SATURDAY MORNING. A COLD FRONT WILL MOVE ACROSS LAKE SUPERIOR LATE FRIDAY NIGHT AND SATURDAY MORNING CAUSING WINDS TO SHIFT NORTH AND NORTHWEST ON SATURDAY. AS HIGH PRESSURE OVER MANITOBA NOSES SOUTHEASTWARD OVER ONTARIO LATE SATURDAY THROUGH SUNDAY...WINDS WILL REMAIN LESS THAN 20 KTS. AS THE RIDGE SHIFTS INTO QUEBEC ON MONDAY AND LOW PRESSURE DEVELOPS ACROSS THE ROCKIES...THERE WILL BE A STRENGTHENING OF SOUTHERLY WINDS AGAIN. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN...FROST ADVY MIZ004>007-010-011-013-014-085 UNTIL 8AM EDT THIS MORNING. LAKE SUPERIOR...GALE WATCH LSZ264-266-267 LATE TONIGHT THRU FRI MORNING. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/DISCUSSION...ROLFSON AVIATION...KC MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 833 PM CDT FRI SEP 19 2008 .DISCUSSION... UPDATE TO FORECAST WILL MAINLY BE TO UPDATE WORDING FOR THE OVERNIGHT PERIOD... WITH MINIMAL CHANGES TO THE GOING FORECAST. FRONTAL BOUNDARY CONTINUES TO SLOWLY SAG SOUTHEASTWARD... WITH CONVECTION DISSIPATING AS DAYTIME INSTABILITY FADES. SOME ELEVATED INSTABILITY WILL REMAIN ACROSS THE SOUTHERN PORTION OF THE AREA THROUGH THE OVERNIGHT HOURS... ALTHOUGH THERE APPEARS TO BE VERY LIMITED FORCING TO GET ANY ELEVATED ACTIVITY GOING. HOWEVER... WITH THE NAM... RUC... AND LOCAL LAPSWRF KEEPING SOME NEARLY SATURATED RH IN THE 850-700MB LAYER THROUGH 12Z IT WOULD BE TOUGH TO RULE OUT AN ISOLATED SHRA/TSRA. THE BETTER FORCING... OWING TO FRONTOGENESIS AND THE ACTUAL 1000-850MB BAROCLINIC ZONE... IS FARTHER NORTH NEAR WHERE THE STRONGER CONVECTION IN NORTHEAST MINNESOTA WAS EARLIER IN THE EVENING. THIS DOES DROP SOUTHEASTWARD OVERNIGHT... ALTHOUGH IT WEAKENS AND WITH THE BOUNDARY LAYER STABILIZING... DO NOT BELIEVE IT WILL BE ABLE TO KICK OFF ANY FURTHER ACTIVITY. KMPX 00Z RAOB SUGGESTED BEST POTENTIAL FOR ANY ELEVATED PARCEL WILL BE FROM AROUND 800MB... WITH THE POTENTIAL OF 400-800 J/KG CAPE... SO IF SOMETHING CAN BE KICKED OFF THERE IS STILL A CHANCE FOR SOME THUNDER. SO... WILL MAINTAIN THE VERY LOW SLIGHT CHANCE POPS IN THE PREVIOUS FORECAST FOR THE SOUTHEAST PORTION OF THE AREA FOR THE OVERNIGHT HOURS. UPDATES TO CLOUD COVER AND TEMPERATURES WILL BE MINOR... AND WILL SIMPLY REFLECT CURRENT TRENDS. && .AVIATION.../00Z TAF ISSUANCE/ /ISSUED 534 PM CDT FRI SEP 19 2008/ VFR CONDS WL PREVAIL THRU THE VALID TAF PD. LEFT A VCSH DURG THE FIRST FEW HRS OF THE TAF AT MSP AND RNH WITH RESIDUAL AFTN SHRA REMAINING NEAR THOSE SITES. WINDS WL SHIFT TO A NERLY DIRN BEHIND THE CDFNTL PASSAGE LATE TNGT...WITH SPDS REMAINING BLO 10 KTS DURG THE AFTN TMRW. && .PREV DISCUSSION... /ISSUED AT 144 PM CDT FRI SEP 19 2008/ WEAK FRONTAL BOUNDARY ALONG WITH SOME WEAK POSITIVE VORTICITY ADVECTION WAS AIDING THE DEVELOPMENT OF SHRA/TSRA AHEAD OF THE FRONT ACRS PORTIONS OF SOUTHERN MN INTO WESTERN WISCONSIN. THE LATEST IR SATELLITE IMAGERY SHOWED A MINOR IMPLUSE OVR CNTRL MN...THIS WAVE WAS ASLO HELPING WITH THE INITATION AND MAINTENANCE OF THE PRECIP. THE IMPLUSE IS FORECAST TO MOVE EAST ACRS NORTHERN WI THIS EVENING. WL KEEP SOME SMALL POPS GOING OVER THE SOUTHERN THIRD OF THE STATE THIS EVENING. ELSEWHERE...SKIES ARE EXPECTED TO CLEAR NORTH OF THE FRONTAL BOUNDARY OVERNIGHT...WHILE SOME PATCHY CLOUDS OR BROKEN LAYER OCCURS JUST SOUTH OF IT. SATURDAY...WEAK FRONT STALLED OVER THE SOUTHERN THIRD OF THE STATE...WILL BEGIN TO LIFT NORTH AS WARM FRONT LATE IN THE DAY. WL GO ALONG WITH PREVIOUS FORECAST...A LEAVE SOME SMALL POPS IN VICINITY OF THE FRONT. MEDIUM RANGE IN GOOD AGREEMENT...WITH THE OVERALL UPPER AIR PATTERN INTO THE NEXT WEEK. LONGWAVE UPPER RIDGE WILL SLOWLY BUILD AND MOVE EAST OVER THE CENTRAL CONUS. MODERATE SUBSIDENCE ALOFT SHOULD KEEP MOST AREAS DRY SATURDAY NIGHT INTO MONDAY MORNING. BY MONDAY AFTERNOON...THE UPPER AIR PATTERN SHIFTS TO MORE SOUTHWESTERLY AIRFLOW OVER THE MIDWEST WITH PRECIP CHANCES INCREASING FROM WEST TO EAST OVER THE FORECAST AREA MONDAY INTO TUESDAY. THE SHORT WAVE TROUGH FINALLY LIFTS EAST THROUGH OUR CWA WEDNESDAY. EXTENDED OUTLOOK...LTL CHANGE TO THE HPC GUIDANCE AND LEFT SOME POPS TOWARD END OF NEW WORK WEEK. SHORTWAVE TROUGH FORECAST TO CARVE OUT OVER THE UPPER MIDWEST...SATURDAY...LOOKS QUESTIONABLE...BY THE LATEST GFS90 MODEL. FAST ZONAL FLOW OVER THE NORTHERN TIER U.S. FORECAST CONFIDENCE IS SLOW. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ TRH/KAT/JVM mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 819 PM CDT FRI SEP 19 2008 .UPDATE...THE STORMS HAVE FINALLY STARTED TO SHOW SOME SIGN OF BREAKING UP AND HAVE WEAKENED SOMEWHAT AS OF 815 PM. THIS IS ABOUT ON TRACK WITH THE CURRENT THINKING OF STORMS DIMINISHING BETWEEN 01Z AND 0130Z...AND DISSIPATING BETWEEN 02Z AND 03Z. THE STORMS SEEM TO HAVE BEEN KICKED OFF IN AN AREA OF DRY MID/UPPER LEVEL AIR PER WATER VAPOR...WITH FAVORABLE LOW LEVEL INSTABILITY AND THERMODYNAMIC PROFILE/LAPSE RATES. ALSO HELPED ALONG BY FAVORABLE EFFECTIVE SHEAR AND THE FRONTAL BOUNDARY. WITH SUNSET...THE STORMS SHOULD DIMINISH NICELY DURING THE REMAINDER OF THE EVENING...ALTHOUGH WILL STILL CARRY ISOLATED MENTION THROUGH MIDNIGHT. OTHER THAN THAT...ZONES/GRIDS APPEAR TO BE IN GOOD SHAPE AND WILL LIKELY NOT MAKE MANY CHANGES TO THEM FOR THE OVERNIGHT. EXPECT TO SEND ZFP AND UPDATED GRIDS BETWEEN 830 AND 9 PM. WE WOULD GREATLY APPRECIATE CALLING ANY REPORTS INTO THE NWS THIS EVENING. && .PREV DISCUSSION... /ISSUED 734 PM CDT FRI SEP 19 2008/ MESOSCALE UPDATE...THE SEVERE STORM ACROSS NORTHERN LAKE COUNTY HAD MAINTAINED ITSELF NICELY OVER THE PAST FEW HOURS. WITHIN THE PAST 15 MINUTES OR SO...IT STARTED TO EXHIBIT SOME SIGNS OF DEVELOPING A HOOK ECHO...AND WE HAVE ISSUED A TORNADO WARNING. OVER THE PAST FEW MINUTES...THE STORM HAD STARTED TO UNDERGO A TRANSFORMATION YET AGAIN. THE STORM WAS MOVING THROUGH A SPARSELY POPULATED AREA...AND WE HAVE NOT HAD ANY REPORTS AS OF YET. STILL LOOKING LIKE A CHANCE OF SEVERE THROUGH 01Z...OR PERHAPS 0130Z...AND THEN DIMINISHING. MESOANALYSIS INDICATES SOME TORNADO POTENTIAL...ALTHOUGH THINK LCL LEVELS MAY BE A BIT HIGH. IF ANYONE HAS REPORTS IN THIS AREA...PLEASE RELAY THEM TO US AT THE NWS. PREV DISCUSSION... /ISSUED 648 PM CDT FRI SEP 19 2008/ MESOSCALE UPDATE...THE STORM NEAR BASSWOOD LAKE HAD STRENGTHENED CONSIDERABLY AS OF 640 PM...WITH MAX DBZ OF AROUND 70 DBZ. DEFINITELY NOT BAD FOR MID/LATE SEPTEMBER. FOR THE DAY...50 DBZ AROUND 25-28K SHOULD BE SEVERE...BUT THIS PARTICULAR STORM HAD A 50 DBZ HEIGHT OF AROUND 35K FEET. THE RUC PICKED UP ON THIS STORM ABSOLUTELY PHENOMENALLY...ALBEIT A BIT FURTHER WEST. THE RUC KEEPS THIS STUFF AROUND THROUGH AROUND 01Z...AND THEN TRIES TO DISSIPATE THE STORMS FROM 02-03Z. THIS THINKING SOUNDS GOOD WITH SUNSET APPROACHING. ADDITIONAL STORMS MAY YET DEVELOP TO THE SOUTH AND WEST OF THIS AREA...ALONG THE FRONTAL BOUNDARY...SO WILL KEEP A CLOSE EYE FOR NEW STORM DEVELOPMENT GIVEN SOME TCU DEVELOPMENT. PREV DISCUSSION... /ISSUED 620 PM CDT FRI SEP 19 2008/ UPDATE...HAVE UPDATED ZONES/GRIDS TO ADD ISOLATED STORMS ACROSS THE ENTIRE REGION WITH FRONT MOVING SOUTHEAST ACROSS THE AREA. ONE SUCH STORM DEVELOPED NORTHWEST OF BASSWOOD LAKE...AND WAS MOVING E/SE. WILL MONITOR THIS STORM IN THE EVENT IT STRENGTHENS FURTHER WHEN IT ENTERS INTO NRN LAKE/NW COOK COUNTIES. RIGHT NOW MOST OF THE ENERGY WAS NORTH OF THE BORDER...BUT WILL SOON MOVE INTO THE CWA. STRONG WIND CONVERGENCE ALONG THE FRONT COULD IGNITE A FEW MORE STORMS ALONG THE FRONT THIS EVENING. MESOANALYSIS PAGE OF SPC INDICATES MUCAPE OF AROUND 2000 J/KG WITH LITTLE INHIBITION. STEEP LAPSE RATES AND MOISTURE POOLING ALONG THE FRONT COULD LEAD TO FURTHER DEVELOPMENT IF THE STORMS ARE ABLE TO SUSTAIN THEMSELVES. FIRST THOUGHTS ARE THAT THE POTENTIAL WILL EXIST FOR A FEW STORMS TO BECOME SEVERE OVER THE NEXT FEW HOURS...BUT WILL DIMINISH RAPIDLY AS SUNSET APPROACHES. SUPERCELL COMPOSITE PARAMETER OF BETWEEN 4 AND 8 OFF THE SPC WEBSITE...SO WILL BE TAKING THE THREAT VERY SERIOUSLY THIS EVENING. PREV DISCUSSION... /ISSUED 356 PM CDT FRI SEP 19 2008/ DISCUSSION...LATEST KDLH RADAR IMAGERY SHOWS A LINE OF SCATTERED SHOWERS AND THUNDERSTORMS EXTENDING ACROSS NORTHWESTERN WISCONSIN AND PINE COUNTY THIS AFTERNOON. THIS ACTIVITY IS ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE DIGGING SE ACROSS THE AREA...PRECEDING THE COLD FRONT WHICH IS JUST ENTERING THE NW CORNER OF OUR CWA. THE PRECIPITATION WILL CONTINUE TO DISSIPATE THROUGH EARLY THIS EVENING...AND END BY MIDNIGHT. THE COLD FRONT WILL TRACK SOUTHEAST ACROSS OUR FCST AREA TONIGHT...EXITING TO THE SOUTH OF THE NORTHLAND LATE TONIGHT. HIGH PRESSURE FROM CANADA WILL THEN BUILD SOUTH OVER THE CWA TOMORROW...BRINGING COOLER TEMPERATURES AND DRY CONDITIONS. THE CENTER OF THE HIGH WILL MOVE OFF TO THE EAST OF OUR CWA ON SUNDAY...ALLOWING FOR RETURN SOUTHERLY FLOW TO DEVELOP WHICH WILL IN TURN INITIATE WAA ACROSS THE UPPER MIDWEST. AS MOISTURE AND TEMPS INCREASE ACROSS THE AREA...THE AIRMASS WILL DESTABILIZE SUNDAY THRU TUESDAY. A COLD FRONT IS PROGGED TO PROPAGATE ACROSS OUR CWA TUESDAY AND TUESDAY NIGHT...TAPPING THIS INCREASING MOISTURE AND INSTABILITY...AND BRINGING ANOTHER ROUND OF SHOWERS AND STORMS TO OUR FCST AREA. HIGH TEMPERATURES WILL DROP 10 TO 20 DEGREES ACROSS THE NORTHLAND BETWEEN TODAY TO TOMORROW. AS WINDS TURN OUT OF THE NORTHEAST...THE COOLER TEMPS WILL ESPECIALLY BE NOTICEABLE ALONG THE LAKE SUPERIOR SHORELINE. AVIATION...ISOLD -SHRA/-TSRA WILL AFFECT MAINLY KDLH AND KHYR THROUGH 21-23Z TIME FRAME AS AN UPPER LEVEL SHORT WAVE CROSSES THE WESTERN GREAT LAKES. A COLD FRONT IS FORECAST TO MOVE THROUGH NE MN THIS EVENING AND NW WI OVERNIGHT. LOOK FOR A WIND SHIFT TO THE NW AFTER FROPA. BY 12Z SATURDAY...THE WIND WILL SWING AROUND TO THE NE AS HIGH PRESSURE FROM CANADA BUILDS INTO THE AREA. && POINT TEMPS/POPS... DLH 50 58 44 62 / 20 10 10 20 INL 42 58 39 68 / 20 10 10 20 BRD 50 68 48 73 / 20 10 10 10 HYR 50 66 41 69 / 20 10 10 20 ASX 51 59 43 65 / 20 10 10 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ DAP mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 734 PM CDT FRI SEP 19 2008 .MESOSCALE UPDATE...THE SEVERE STORM ACROSS NORTHERN LAKE COUNTY HAD MAINTAINED ITSELF NICELY OVER THE PAST FEW HOURS. WITHIN THE PAST 15 MINUTES OR SO...IT STARTED TO EXHIBIT SOME SIGNS OF DEVELOPING A HOOK ECHO...AND WE HAVE ISSUED A TORNADO WARNING. OVER THE PAST FEW MINUTES...THE STORM HAD STARTED TO UNDERGO A TRANSFORMATION YET AGAIN. THE STORM WAS MOVING THROUGH A SPARSELY POPULATED AREA...AND WE HAVE NOT HAD ANY REPORTS AS OF YET. STILL LOOKING LIKE A CHANCE OF SEVERE THROUGH 01Z...OR PERHAPS 0130Z...AND THEN DIMINISHING. MESOANALYSIS INDICATES SOME TORNADO POTENTIAL...ALTHOUGH THINK LCL LEVELS MAY BE A BIT HIGH. IF ANYONE HAS REPORTS IN THIS AREA...PLEASE RELAY THEM TO US AT THE NWS. && .PREV DISCUSSION... /ISSUED 648 PM CDT FRI SEP 19 2008/ MESOSCALE UPDATE...THE STORM NEAR BASSWOOD LAKE HAD STRENGTHENED CONSIDERABLY AS OF 640 PM...WITH MAX DBZ OF AROUND 70 DBZ. DEFINITELY NOT BAD FOR MID/LATE SEPTEMBER. FOR THE DAY...50 DBZ AROUND 25-28K SHOULD BE SEVERE...BUT THIS PARTICULAR STORM HAD A 50 DBZ HEIGHT OF AROUND 35K FEET. THE RUC PICKED UP ON THIS STORM ABSOLUTELY PHENOMENALLY...ALBEIT A BIT FURTHER WEST. THE RUC KEEPS THIS STUFF AROUND THROUGH AROUND 01Z...AND THEN TRIES TO DISSIPATE THE STORMS FROM 02-03Z. THIS THINKING SOUNDS GOOD WITH SUNSET APPROACHING. ADDITIONAL STORMS MAY YET DEVELOP TO THE SOUTH AND WEST OF THIS AREA...ALONG THE FRONTAL BOUNDARY...SO WILL KEEP A CLOSE EYE FOR NEW STORM DEVELOPMENT GIVEN SOME TCU DEVELOPMENT. PREV DISCUSSION... /ISSUED 620 PM CDT FRI SEP 19 2008/ UPDATE...HAVE UPDATED ZONES/GRIDS TO ADD ISOLATED STORMS ACROSS THE ENTIRE REGION WITH FRONT MOVING SOUTHEAST ACROSS THE AREA. ONE SUCH STORM DEVELOPED NORTHWEST OF BASSWOOD LAKE...AND WAS MOVING E/SE. WILL MONITOR THIS STORM IN THE EVENT IT STRENGTHENS FURTHER WHEN IT ENTERS INTO NRN LAKE/NW COOK COUNTIES. RIGHT NOW MOST OF THE ENERGY WAS NORTH OF THE BORDER...BUT WILL SOON MOVE INTO THE CWA. STRONG WIND CONVERGENCE ALONG THE FRONT COULD IGNITE A FEW MORE STORMS ALONG THE FRONT THIS EVENING. MESOANALYSIS PAGE OF SPC INDICATES MUCAPE OF AROUND 2000 J/KG WITH LITTLE INHIBITION. STEEP LAPSE RATES AND MOISTURE POOLING ALONG THE FRONT COULD LEAD TO FURTHER DEVELOPMENT IF THE STORMS ARE ABLE TO SUSTAIN THEMSELVES. FIRST THOUGHTS ARE THAT THE POTENTIAL WILL EXIST FOR A FEW STORMS TO BECOME SEVERE OVER THE NEXT FEW HOURS...BUT WILL DIMINISH RAPIDLY AS SUNSET APPROACHES. SUPERCELL COMPOSITE PARAMETER OF BETWEEN 4 AND 8 OFF THE SPC WEBSITE...SO WILL BE TAKING THE THREAT VERY SERIOUSLY THIS EVENING. PREV DISCUSSION... /ISSUED 356 PM CDT FRI SEP 19 2008/ DISCUSSION...LATEST KDLH RADAR IMAGERY SHOWS A LINE OF SCATTERED SHOWERS AND THUNDERSTORMS EXTENDING ACROSS NORTHWESTERN WISCONSIN AND PINE COUNTY THIS AFTERNOON. THIS ACTIVITY IS ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE DIGGING SE ACROSS THE AREA...PRECEDING THE COLD FRONT WHICH IS JUST ENTERING THE NW CORNER OF OUR CWA. THE PRECIPITATION WILL CONTINUE TO DISSIPATE THROUGH EARLY THIS EVENING...AND END BY MIDNIGHT. THE COLD FRONT WILL TRACK SOUTHEAST ACROSS OUR FCST AREA TONIGHT...EXITING TO THE SOUTH OF THE NORTHLAND LATE TONIGHT. HIGH PRESSURE FROM CANADA WILL THEN BUILD SOUTH OVER THE CWA TOMORROW...BRINGING COOLER TEMPERATURES AND DRY CONDITIONS. THE CENTER OF THE HIGH WILL MOVE OFF TO THE EAST OF OUR CWA ON SUNDAY...ALLOWING FOR RETURN SOUTHERLY FLOW TO DEVELOP WHICH WILL IN TURN INITIATE WAA ACROSS THE UPPER MIDWEST. AS MOISTURE AND TEMPS INCREASE ACROSS THE AREA...THE AIRMASS WILL DESTABILIZE SUNDAY THRU TUESDAY. A COLD FRONT IS PROGGED TO PROPAGATE ACROSS OUR CWA TUESDAY AND TUESDAY NIGHT...TAPPING THIS INCREASING MOISTURE AND INSTABILITY...AND BRINGING ANOTHER ROUND OF SHOWERS AND STORMS TO OUR FCST AREA. HIGH TEMPERATURES WILL DROP 10 TO 20 DEGREES ACROSS THE NORTHLAND BETWEEN TODAY TO TOMORROW. AS WINDS TURN OUT OF THE NORTHEAST...THE COOLER TEMPS WILL ESPECIALLY BE NOTICEABLE ALONG THE LAKE SUPERIOR SHORELINE. AVIATION...ISOLD -SHRA/-TSRA WILL AFFECT MAINLY KDLH AND KHYR THROUGH 21-23Z TIME FRAME AS AN UPPER LEVEL SHORT WAVE CROSSES THE WESTERN GREAT LAKES. A COLD FRONT IS FORECAST TO MOVE THROUGH NE MN THIS EVENING AND NW WI OVERNIGHT. LOOK FOR A WIND SHIFT TO THE NW AFTER FROPA. BY 12Z SATURDAY...THE WIND WILL SWING AROUND TO THE NE AS HIGH PRESSURE FROM CANADA BUILDS INTO THE AREA. && POINT TEMPS/POPS... DLH 50 58 44 62 / 20 10 10 20 INL 42 58 39 68 / 20 10 10 20 BRD 50 68 48 73 / 20 10 10 10 HYR 50 66 41 69 / 20 10 10 20 ASX 51 59 43 65 / 20 10 10 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ DAP mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 648 PM CDT FRI SEP 19 2008 .MESOSCALE UPDATE...THE STORM NEAR BASSWOOD LAKE HAD STRENGTHENED CONSIDERABLY AS OF 640 PM...WITH MAX DBZ OF AROUND 70 DBZ. DEFINITELY NOT BAD FOR MID/LATE SEPTEMBER. FOR THE DAY...50 DBZ AROUND 25-28K SHOULD BE SEVERE...BUT THIS PARTICULAR STORM HAD A 50 DBZ HEIGHT OF AROUND 35K FEET. THE RUC PICKED UP ON THIS STORM ABSOLUTELY PHENOMENALLY...ALBEIT A BIT FURTHER WEST. THE RUC KEEPS THIS STUFF AROUND THROUGH AROUND 01Z...AND THEN TRIES TO DISSIPATE THE STORMS FROM 02-03Z. THIS THINKING SOUNDS GOOD WITH SUNSET APPROACHING. ADDITIONAL STORMS MAY YET DEVELOP TO THE SOUTH AND WEST OF THIS AREA...ALONG THE FRONTAL BOUNDARY...SO WILL KEEP A CLOSE EYE FOR NEW STORM DEVELOPMENT GIVEN SOME TCU DEVELOPMENT. && .PREV DISCUSSION... /ISSUED 620 PM CDT FRI SEP 19 2008/ UPDATE...HAVE UPDATED ZONES/GRIDS TO ADD ISOLATED STORMS ACROSS THE ENTIRE REGION WITH FRONT MOVING SOUTHEAST ACROSS THE AREA. ONE SUCH STORM DEVELOPED NORTHWEST OF BASSWOOD LAKE...AND WAS MOVING E/SE. WILL MONITOR THIS STORM IN THE EVENT IT STRENGTHENS FURTHER WHEN IT ENTERS INTO NRN LAKE/NW COOK COUNTIES. RIGHT NOW MOST OF THE ENERGY WAS NORTH OF THE BORDER...BUT WILL SOON MOVE INTO THE CWA. STRONG WIND CONVERGENCE ALONG THE FRONT COULD IGNITE A FEW MORE STORMS ALONG THE FRONT THIS EVENING. MESOANALYSIS PAGE OF SPC INDICATES MUCAPE OF AROUND 2000 J/KG WITH LITTLE INHIBITION. STEEP LAPSE RATES AND MOISTURE POOLING ALONG THE FRONT COULD LEAD TO FURTHER DEVELOPMENT IF THE STORMS ARE ABLE TO SUSTAIN THEMSELVES. FIRST THOUGHTS ARE THAT THE POTENTIAL WILL EXIST FOR A FEW STORMS TO BECOME SEVERE OVER THE NEXT FEW HOURS...BUT WILL DIMINISH RAPIDLY AS SUNSET APPROACHES. SUPERCELL COMPOSITE PARAMETER OF BETWEEN 4 AND 8 OFF THE SPC WEBSITE...SO WILL BE TAKING THE THREAT VERY SERIOUSLY THIS EVENING. PREV DISCUSSION... /ISSUED 356 PM CDT FRI SEP 19 2008/ DISCUSSION...LATEST KDLH RADAR IMAGERY SHOWS A LINE OF SCATTERED SHOWERS AND THUNDERSTORMS EXTENDING ACROSS NORTHWESTERN WISCONSIN AND PINE COUNTY THIS AFTERNOON. THIS ACTIVITY IS ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE DIGGING SE ACROSS THE AREA...PRECEDING THE COLD FRONT WHICH IS JUST ENTERING THE NW CORNER OF OUR CWA. THE PRECIPITATION WILL CONTINUE TO DISSIPATE THROUGH EARLY THIS EVENING...AND END BY MIDNIGHT. THE COLD FRONT WILL TRACK SOUTHEAST ACROSS OUR FCST AREA TONIGHT...EXITING TO THE SOUTH OF THE NORTHLAND LATE TONIGHT. HIGH PRESSURE FROM CANADA WILL THEN BUILD SOUTH OVER THE CWA TOMORROW...BRINGING COOLER TEMPERATURES AND DRY CONDITIONS. THE CENTER OF THE HIGH WILL MOVE OFF TO THE EAST OF OUR CWA ON SUNDAY...ALLOWING FOR RETURN SOUTHERLY FLOW TO DEVELOP WHICH WILL IN TURN INITIATE WAA ACROSS THE UPPER MIDWEST. AS MOISTURE AND TEMPS INCREASE ACROSS THE AREA...THE AIRMASS WILL DESTABILIZE SUNDAY THRU TUESDAY. A COLD FRONT IS PROGGED TO PROPAGATE ACROSS OUR CWA TUESDAY AND TUESDAY NIGHT...TAPPING THIS INCREASING MOISTURE AND INSTABILITY...AND BRINGING ANOTHER ROUND OF SHOWERS AND STORMS TO OUR FCST AREA. HIGH TEMPERATURES WILL DROP 10 TO 20 DEGREES ACROSS THE NORTHLAND BETWEEN TODAY TO TOMORROW. AS WINDS TURN OUT OF THE NORTHEAST...THE COOLER TEMPS WILL ESPECIALLY BE NOTICEABLE ALONG THE LAKE SUPERIOR SHORELINE. AVIATION...ISOLD -SHRA/-TSRA WILL AFFECT MAINLY KDLH AND KHYR THROUGH 21-23Z TIME FRAME AS AN UPPER LEVEL SHORT WAVE CROSSES THE WESTERN GREAT LAKES. A COLD FRONT IS FORECAST TO MOVE THROUGH NE MN THIS EVENING AND NW WI OVERNIGHT. LOOK FOR A WIND SHIFT TO THE NW AFTER FROPA. BY 12Z SATURDAY...THE WIND WILL SWING AROUND TO THE NE AS HIGH PRESSURE FROM CANADA BUILDS INTO THE AREA. && POINT TEMPS/POPS... DLH 78 50 58 44 / 30 20 10 10 INL 80 42 58 39 / 20 20 10 10 BRD 82 50 68 48 / 40 20 10 10 HYR 79 50 66 41 / 30 20 10 10 ASX 80 51 59 43 / 30 20 10 10 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ DAP mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 316 PM CDT THU SEP 18 2008 .DISCUSSION... MOD TO STRONG SSW FLOW WILL CONTINUE THIS EVENING AHEAD OF THE LOW PRESSURE TROUGH OVER THE CENTRAL DAKOTAS. DECENT DIFFERENTIAL TEMP ADVECTION DEVELOPS OVER THE EASTERN DAKOTAS INTO WEST CENTRAL MN LATE TONIGHT AND FRIDAY MORNING BUT HIGHER K INDICES DO NOT WORK INTO CENTRAL MN UNTIL FRIDAY. SOME ELEVATED CAPE SHOWING UP IN THE FORECAST SOUNDINGS. UPPER AIR SUPPORT ON THE WEAK SIDE THOUGH. WILL HOWEVER INTRODUCE A SMALL POP ON FRIDAY IN NORTH CWA AS BETTER LOW LEVEL MOISTURE TRANSPORT COINCIDES WITH HIGHER K INDICES. SREF POPS MAXIMIZE IN THIS AREA AS WELL. WILL ALSO KEEP THE SMALL POP OVER WEST CENTRAL WI FRIDAY NIGHT AS THE FRONT TRAILS OFF. NEGATIVE FACTOR WILL BE AN INITIAL CAP. SHOULD BE A WARM DAY AHEAD OF THE FRONT AND 80S COMMON MOST LOCATIONS. CAN`T RULE OUT A COUPLE UPPER 80S KCNB...KDXX AREA...SIMILAR TO TUESDAY. THE BOUNDARY WILL RETREAT TO THE NORTH AGAIN SATURDAY AND SATURDAY NIGHT. THERE IS SOME RISK OF PRECIP BUT THE TEMP GRADIENT WILL DEVELOP MORE OVER NORTHEAST MN. WILL LEAVE OUT AT THIS TIME BU THE BEST CHANCE WOULD BE OVER CENTRAL MN. NEXT BEST PRECIP CHANCES STILL APPEAR TO BE MID WEEK. BEST INCREASE IN GFS ENSEMBLE POPS IS ON WED. THERE IS UNCERTAINTY IN THE SPEED AND INTENSITY OF THE UPPER TROUGH IN THE WEST AS RIDGE BUILDS IN THE EAST...ALONG WITH A SPLIT POTENTIAL TO OUR SOUTH. WILL KEEP SOME POPS IN THROUGH WEDNESDAY NIGHT AND THURSDAY BUT LESSER CHANCES ON THURSDAY. && .AVIATION.../18Z TAF ISSUANCE/ BREEZY SOUTHERLY WINDS DEVELOPING ACROSS MUCH OF THE REGION THIS AFTN AS SURFACE PRESSURE GRADIENT TIGHTENS AND MOSTLY SUNNY SKIES HAVE ALLOWED FOR FULL MIXING TO ESTABLISH ITSELF. GOING SUSTAINED WINDS AND GUSTS IN TAF LOOK GOOD FOR THIS AFTN GIVEN OBSERVATIONAL TRENDS AND RUC PREDICTIONS OF MIXING HEIGHTS. WOOD LAKE PROFILER SHOWING 40 KTS AT 1-2 KFT...SO GUSTS OF 75 TO 80 PERCENT OF THAT /OR NEAR 30 KTS/ ARE EXPECTED AT AXN AND RWF. MPX VAD PROFILER REVEALS LESS SPEEDS...BUT STILL 20-25 KTS AT 2-4 KFT...WELL WITHIN THE MIXING LAYER. SOME REGENERATING 6-8 KFT CLOUDS EXPECTED ON GRADUALLY MOISTENING WARM AIR ADVECTION IN THAT LAYER. SFC WINDS TO LOSE THEIR GUSTS TONIGHT WHILE SUSTAINED STAY UP IN THE 10-14 KT CATEGORY. WEAK SFC TROUGH TO MOVE INTO WRN MN JUST PRIOR TO DAYBREAK TOMORROW. SOME SCT LIGHT SHOWERS ALONG OR BEHIND THIS SEEM POSSIBLE WITH MARGINAL LAPSE RATES AND ASSOCIATED ELEVATED INSTABILITY ENOUGH TO KEEP THEM ALIVE AS THEY HEAD EAST FROM ND/SD. HAVE A PROB GROUP AT AXN TO ACCOUNT FOR THIS CONFIDENCE. SEEMS LIKE A SMALL CHANCE FOR A SHOWER JUST BEYOND TAF PERIOD...FRI AFTN AND EVE...ACROSS OTHER TAF SITES DUE TO THIS TROUGH PASSAGE. MAY NOT BE WORTH MENTION THOUGH AT 00Z. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JPR/MTF mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 1000 PM CDT FRI SEP 19 2008 .UPDATE...WATER VAPOR IMAGERY/RUC ANALYSIS SHOWS THE CIRCULATION AROUND THE UPPER LOW OVER SOUTHERN MISSOURI WITH A SHORT WAVE LIFTING NORTH INTO TENNESSEE FROM NORTHEAST MISSISSIPPI. THIS SHORTWAVE HELPED MAINTAIN AN AREA OF THUNDERSTORMS EARLIER THIS EVENING OVER OUR NORTHEAST ZONES. IN THE WAKE OF THE SHORTWAVE DRIER AIR AND WEAK SUBSIDENCE MOVED INTO THE NORTHWESTERN PORTIONS OF OUR CWA. THIS HAS ERODED CLOUD COVER OVER OUR DELTA REGION. MODELS CONTINUE TO SHOW REDEVELOPMENT OF SHOWERS AFTER MIDNIGHT OVER MUCH OF THE AREA. LOCAL RADARS ALSO SHOW SOME LIGHT SHOWERS REDEVELOPING OVER SOUTHWEST MISSISSIPPI MOVING NORTHEAST INTO CENTRAL MISSISSIPPI. EXPECT RAIN CHANCES WILL BE LIMITED IN OUR NORTHWEST BUT CONTINUE GENERALLY ALONG AND EAST OF THE NATCHEZ TRACE. HAVE UPDATED FORECAST TO REDUCE POPS IN THE WEST. DEW POINTS ARE RUNNING HIGHER AGAIN TONIGHT THAN GUIDANCE SUGGESTS. MORNING LOWS WERE SEVERAL DEGREES WARMER THAN EXPECTED THIS MORNING. WITH CLOUDS AND RAIN CHANCES CONTINUING OVERNIGHT HAVE RAISED FORECAST MIN TEMPS SEVERAL DEGREES IN THE NORTH. UPDATES HAVE BEEN POSTED. /22/ && .PREVIOUS DISCUSSION...SHORT TERM...WARM AIR ADVECTION WILL BEGIN TO WANE TONIGHT INTO SATURDAY BUT WILL REMAIN SUFFICIENT TO MAINTAIN A CHANCE OF RAIN FOR MOST AREAS. LOW LEVEL FLOW WILL BEGIN TO DECREASE AND BACK A BIT MORE SELY AS THE LOW LEVEL TROUGH EDGES SLIGHTLY WWD AND WEAKENS IN THE WAKE OF THE INITIAL UPPER WAVE TODAY. MID LEVEL TROUGHING WILL CONTINUE THROUGH THE WEEKEND AND MAINTAIN ENOUGH GENERAL LIFT AND MOISTURE TO CONTRIBUTE TO CONVECTION...PROVIDING A COOL POOL ALOFT OVER HEALTHY 850 MB THETAE AIR. MODELS ARE PULLING BACK ON THE EXTENT OF ADVECTION OF DRIER AND COOLER AIR FROM THE EAST THIS WEEKEND...GENERALLY CONFINING IT TO JUST EAST OF THE FORECAST AREA TOMORROW AND DELAYING WEAK DRY AIR ADVECTION UNTIL SUNDAY. THIS WILL KEEP WEEKEND LOWS CLOSER TO NORMAL. SPEAKING OF NORMAL...THE DAILY NORMALS FOR HIGH TEMPERATURE COOL NOTICEABLY THIS MONTH AS WE MOVE INTO FALL. AS AN EXAMPLE, THE NORMAL HIGH TEMPERATURE FOR JACKSON FOR SEPTEMBER 1ST WAS 90 DEGREES WHILE THE NORMAL HIGH TEMPERATURE FOR TODAY IS 86. THE DAILY NORMAL HIGH FOR JACKSON BY THE LAST DAY OF THIS MONTH WILL FALL TO 82 DEGREES. .LONG TERM...CONFIDENCE IS GROWING IN THE MED RANGE/LONG TERM PORTION OF THE FORECAST AS THERE IS MORE RUN TO RUN CONSISTENCY WITH THE MODELS AND GOOD AGREEMENT BETWEEN THE MODELS AND THE ENSEMBLES. THE UPPER TROUGH WEAKENS SUN NIGHT AND THIS WILL BEGIN THE PERIOD WHERE POPS WILL TREND LOWER. GUID VALUES WERE GOOD FOR THIS PERIOD WITH JUST SOME SLIGHT CHANCE VALUES ACROSS THE SE HALF. EXPECT LOWS IN THE LOWER 60S...MAYBE A BIT WARMER IF CLOUDS CAN REMAIN THICK. BY MON...OUR S/W WILL BE PUSHING EAST AND RIDGING WILL DEVELOP. MID LEVEL HEIGHTS WILL BEGIN TO RISE THIS PERIOD WITH MID LEVEL TEMPS WARMING SEVERAL DEGREES. SKIES WILL BECOME PARTLY CLOUDY AND I WILL ONLY CARRY SOME ISO SHRA CHANCES ACROSS THE EAST PORTION OF THE CWA AS GUID IS OFFERING THOSE VALUES...PLUS I DON`T WANT TO TOTALLY REMOVE PRECIP CHANCES TOO QUICKLY IN CASE THE S/W IS A TAD SLOWER. FOR MON NIGHT THROUGH FRI...RIDGING ALOFT WILL TAKE OVER AND IN THE LOW LEVELS WE WILL SEE A BACKDOOR FRONT PUSH IN DRIER AND SLIGHTLY COOLER AIR. AT THIS TIME...THINGS DON`T LOOK TO BE MUCH COOLER...JUST A REINFORCING SHOT OF DRIER AIR THAT WILL LIKELY ALLOW LOWS TO GET COOLER FOR THE TUE-FRI PERIOD. THE EURO AND GFS ENSEMBLES SHOW THIS AND I HAVE LOWER LOWS SEVERAL DEGREES FOR THOSE PERIODS. AS FOR HIGHS...GUID VALUES LOOKED RIGHT ON AND HAVE FOLLOWED. EXPECT NORMAL HIGHS GENERALLY AROUND 85 ALL WEEK. /CME/ && .AVIATION...UPDATED...ISOLATED THUNDERSTORMS IN VCTY OF GTR WILL REMAIN POSSIBLE THROUGH 06Z. DRIER AIR HAS MOVED INTO THE NORTHWEST AND WILL LIMIT RAIN CHANCES THERE BUT ADDITIONAL SHOWERS ARE EXPECTED THROUGH THE NIGHT OVER THE SOUTHEAST HALF OF THE AREA. MUCH OF THE AREA WILL REMAIN UNDER VFR CONDITIONS THROUGH 06Z. AFTER 06Z MVFR VISIBILITIES AND CEILINGS ARE EXPECTED TO DEVELOP. THESE CONDITIONS WILL LAST THROUGH 14Z BEFORE IMPROVING. SCATTERED COVERAGE OF RAIN IS EXPECTED AGAIN SATURDAY WITH THUNDERSTORMS IN THE MIX FOR THE AFTERNOON. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 64 81 61 80 / 52 55 35 42 MERIDIAN 62 80 61 81 / 43 44 37 42 VICKSBURG 64 82 62 82 / 43 47 30 39 HATTIESBURG 65 81 64 83 / 50 64 37 45 NATCHEZ 65 81 64 82 / 32 56 32 43 GREENVILLE 61 83 61 83 / 26 38 22 30 GREENWOOD 62 81 62 81 / 35 44 26 31 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ 03/CME/7 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTH PLATTE NE 328 AM CDT FRI SEP 19 2008 .DISCUSSION... FORECAST CHALLENGE TODAY THROUGH TUESDAY IS POPS. AT 07Z ISOLATED CONVECTION ACROSS THE FAR NORTHWEST INTO SOUTHERN SOUTH DAKOTA WAS DISSIPATING AS OUTFLOW BOUNDARY LAID OUT HAS DROPPED SOUTHEAST ACROSS WESTERN CHERRY COUNTY. MODELS ARE IN GENERAL AGREEMENT TOWARD GREATER POTENTIAL FOR ISOLATED CONVECTION TODAY THEN AS ENERGY MOVES DOWNSTREAM FROM BUILDING RIDGE ACROSS THE NORTHWEST CONUS THERE WILL BE A BETTER CHANCE FOR RAINFALL LATE SUNDAY THROUGH TUESDAY. TODAY THE CLOUD COVERAGE ACROSS THE NORTH WILL LIFT NORTHEAST WITH MOSTLY SUNNY SKIES AND GOOD SURFACE HEATING. STEEPENING LAPSE RATES WILL LEAD TO ISOLATED HIGH BASED THUNDERSTORMS BY LATE AFTERNOON ACROSS THE WEST. THE RUC13 PLACES THE SURFACE TROUGH TO EXTEND SOUTHWEST FROM NEAR FAR...ABR...TO NEAR CYS THIS MORNING THAT WILL BECOME THE FOCUS FOR THUNDERSTORM DEVELOPMENT INTO THE PANHANDLE THIS AFTERNOON AND POSSIBLY THE OUTFLOW BOUNDARY LAID OUT ACROSS CHERRY COUNTY AS SOUTH WINDS DRAW MOISTURE NORTHWARD TODAY. SOUNDING PROFILES SHOW LIMITED MOISTURE BELOW 10KFT FOR MAINLY HIGH BASED THUNDERSTORMS TO BE SEEN AGAIN TODAY. IN ADDITION...MID LEVEL WINDS WILL BE LIGHT ACROSS THE NORTHWEST WITH ANY STORMS THAT DO FORM TO MOVE SLOWLY AND BE WITHIN CLOSE PROXIMITY TO THE SURFACE TROUGH AS IT DROPS SLOWLY SOUTHEAST DURING THE EVENING. AFTER 9 PM ANY CONVECTION THAT DOES FORM SHOULD BEGIN TO DISSIPATE WITH THE PRIMARY CONCERN TO BE WIND GUSTS ASSOCIATED WITH ANY THUNDERSTORMS THAT DO FORM. TEMPERATURES WILL AGAIN CLIMB INTO THE 80S TODAY...THEN OVERNIGHT LOWS FROM THE UPPER 40S WEST TO MID 50S NORTH CENTRAL. SATURDAY THE UPPER RIDGE AXIS BUILDS EAST TO THE HIGH PLAINS AS A STRONGER SYSTEM ENTERS THE NORTHEAST COAST. INCREASED SUBSIDENCE ALOFT WILL TEND TO INHIBIT STORM DEVELOPMENT UNTIL GOING INTO SUNDAY AS ENERGY EJECTS NORTHEAST TO BRING A CHANCE FOR THUNDERSTORMS SUNDAY AFTERNOON ACROSS THE WEST THEN EXTEND NORTHEAST OVERNIGHT. THE LOW LEVEL JET STRENGTHENS DURING THE PERIOD WITH THE H85 WINDS TO 45 KNOTS TO DEEPEN MOISTURE THROUGH THE DAY FOR INCREASING CLOUDS AND THE CHANCE FOR THUNDERSTORMS SUNDAY AFTERNOON. OUTDOOR ACTIVITIES SUNDAY AFTERNOON COULD BE IMPACTED AS MODELS ARE IN GOOD AGREEMENT WITH EJECTING SEVERAL DISTURBANCES NORTHEAST THROUGH THE EVENING AND OVERNIGHT INTO MONDAY MORNING. CLOUD COVERAGE WILL ALSO IMPACT TEMPERATURES SUNDAY WITH READINGS AROUND 80 FOR THE DAY. SUNDAY NIGHT THROUGH WEDNESDAY THE UPPER RIDGE WILL TRANSITION TO THE EAST WHILE BROAD TROUGHING ACROSS THE WEST WILL LEAD TO GOOD MOISTURE CONVERGENCE ON THE PLAINS. WIDESPREAD CLOUD COVERAGE AND THE CHANCE FOR THUNDERSTORMS WILL CONTINUE THROUGH TUESDAY WHEN A STRONGER DISTURBANCE TRACKS THROUGH THE NORTHWEST TO KICK THE FRONTAL SYSTEM EAST BY WEDNESDAY. THROUGH THE EXTENDED PERIOD TEMPERATURES WILL RANGE FORM DAYTIME HIGHS MAINLY IN THE 70S AND LOWS IN THE 50S THROUGH TUESDAY. THEN AS DRIER AIR SPREADS SOUTHEAST TEMPERATURES BEYOND WEDNESDAY SHOULD BE CLOSE TO NORMALS WITH HIGHS IN THE 70S AND LOWS IN THE 40S. && .AVIATION... VFR IS EXPECTED TODAY AND TONIGHT. THE KLBF TAF IS SUBJECT TO AMENDMENT FOR LOW LEVEL WIND SHEAR THROUGH 13Z THIS MORNING. A STALLED OUT COLD FRONT WILL MEANDER ACROSS NWRN NEB TODAY. ISOLATED THUNDERSTORMS COULD DEVELOP ALONG THE FRONT ACROSS NORTHWEST NEB BETWEEN 21Z-03Z TODAY. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ KECK/CDC ne AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ALBUQUERQUE NM 859 PM MDT FRI SEP 19 2008 .UPDATE... UPDATED TO KEEP ISOLATED THUNDERSTORMS IN THE FORECAST FOR THE REMAINDER OF THE NIGHT IN MOST LOCATIONS. SATELLITE IMAGERY AND RUC 80 ANALYSIS INDICATES A WEAK SHORTWAVE EMBEDED IN THE BACK SIDE OF THE UPPER RIDGE. IT IS DIFFICULT TO RULE OUT AN ISOLATED THUNDERSTORM JUST ABOUT ANYWHERE TONIGHT...AS THIS SHORTWAVE SLOWLY SAGS SOUTHEASTWARD ACROSS THE FORECAST AREA. ALSO ADJUSTED THE WIND FORECAST A BIT IN CENTRAL AREAS...TO MATCH RESENT WEATHER OBSERVATIONS. 44 && .PREV DISCUSSION... 251 PM MDT FRI SEP 19 2008...FAIRLY ACTIVE DAY ACROSS THE STATE AS MID LEVEL MOISTURE ACROSS THE REGION COMBINES WITH UPPER LEVEL SUPPORT PROVIDED BY A PASSING SHORTWAVE TROUGH. FOR THE MOST PART THE STORMS HAVE BEEN BEHAVING THEMSELVES BUT I WOULD NOT RULE OUT A SEVERE STORM OR TWO THIS EVENING...ESPECIALLY OVER EASTERN SECTIONS OF THE STATE. GIVEN THE EVOLVING WEATHER PATTERN AND APPROACHING SYNOPTIC SCALE TROUGH...I WOULD EXPECT THE FOCUS OF ANY CONVECTIVE ACTIVITY TO SHIFT SLIGHTLY EASTWARD TOMORROW...WITH A CONTINUED EMPHASIS ON THE NORTHERN HALF OF THE STATE. THE NEXT INFLUENTIAL WEATHER SYSTEM WILL BE THE TROUGH CURRENTLY ALONG THE WEST COAST. THIS SYSTEM WILL SERVE TO FLATTEN THE RIDGE OVER THE AREA AND USHER IN SOME DRIER AIR LATE THIS WEEKEND AND INTO EARLY NEXT WEEK. ANY CONVECTIVE ACTIVITY OVER THE STATE ON SUNDAY SHOULD BE LIMITED TO THE NORTHERN THIRD WITH AN OVERALL DECREASE IN SHOWERS AND THUNDERSTORMS COMPARED TO SATURDAY. ADDITIONALLY...SOUTHWEST BREEZES SHOULD KICK IN DURING THE LATE MORNING AND AFTERNOON HOURS. BREEZES REMAIN IN THE FORECAST THROUGH MONDAY BEFORE HIGH PRESSURE THEN GRADUALLY BUILDS BACK IN DURING THE MIDDLE PORTION OF THE UPCOMING WEEK WITH A SLIGHT WARMING TREND AND MOSTLY BENIGN WEATHER ON TAP. && .AVIATION... SCATTERED SHOWERS/STORMS WILL DISSIPATE THRU 04Z...WITH MVFR CIGS/VSBYS POSSIBLE IN AND AROUND THE STRONGER STORMS. THE MAIN THREAT FROM STORMS WILL BE GUSTY OUTLFOW WINDS. EXPECTD MID LEVEL CLOUDS TO STICK AROUND IN THE E PLAINS OVERNIGHT WHILE MOST AREAS ACROSS THE WESTERN HALF BECOME MOSTLY CLEAR. PATCHY FOG MAY DEVELOP IN THE VALLEYS OF THE NORTHERN MTNS OVERNIGHT WITH IFR/MVFR POSSIBLE THRU 13Z. ISOLD GUSTY STORMS WILL DEVELOP AGAIN SATURDAY ESPECIALLY OVER THE SANGRE DE CRISTO MTNS. NEXT AVIATION DISCUSSION SCHEDULED FOR 09Z. GUYER && .FIRE WEATHER... SCATTERED SHOWERS AND STORMS THRU EARLY EVENING WILL PRODUCE MAINLY GUSTY WINDS...BRIEF WETTING RAINS...AND CLOUD TO GROUND LIGHTNING STRIKES. WIDESPREAD VERY GOOD TO EXCELLENT RH RECOVERIES ARE LIKELY AGAIN OVERNIGHT UNDER MOSTLY CLEAR SKIES. A FEW MORE STORMS WILL DEVELOP SATURDAY...ESPECIALLY OVER THE SANGRES. MIN RH VALUES WILL RANGE FROM THE TEENS IN THE WEST TO AROUND 30 IN THE EAST. THE WEAK RIDGE CURRENTLY IN PLACE OVER THE AREA WILL BREAK DOWN THRU MONDAY AS A BROAD TROUGH DEEPENS OVER THE WEST COAST. SURFACE WINDS WILL BECOME BREEZY ACROSS THE EASTERN THIRD OF THE AREA IN REPONSE TO 1005MB LOW PRESSURE CENTER DEVELOPING OVER SE COLORADO AHEAD OF THE WEST COAST TROUGH. MIN RH VALUES FALL TO AROUND 20 PCT AREAWIDE IN THIS PATTERN WITH RECOVERIES TRENDING INTO THE 50-60 PCT RANGE. THE AXIS OF THE UPPER TROUGH PASSES THE STATE ON TUESDAY WITH SLIGHTLY COOLER TEMPS AND AFTERNOON BREEZES. ANOTHER RIDGE BEGINS BUILDING OVER THE STATE INTO WEDNESDAY WITH GENERALLY LIGHTER WINDS AND ISOLD AFTERNOON SHOWERS AND STORMS. GUYER && .ABQ WATCHES/WARNINGS/ADVISORIES...NONE. && $$ 44 nm AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ALBUQUERQUE NM 929 PM MDT THU SEP 18 2008 .UPDATE... ISOLATED SHOWERS AND STORMS HAVE SURVIVED PAST SUNSET IN RIGHT REAR QUAD OF JET AND NEAREST EXITING SHORT WAVE TROUGH. MOST OF THIS WILL DISSIPATE BY MIDNIGHT BUT SOME COULD PERSIST LATER...ESPECIALLY IN THE EAST CLOSEST TO DYNAMICS AS PER 00Z NAM. MADE ONLY SLIGHT ADJUSTMENTS TO OVERNIGHT LOWS...KD && .PREV DISCUSSION...254 PM MDT THU SEP 18 2008... SHOWER AND STORM COVERAGE HAS INCREASED MARKEDLY THIS AFTERNOON OVER MUCH OF THE NORTHERN TWO THIRDS OF THE STATE...IN RESPONSE TO MODEST LOW/MID LEVEL MOISTURE AND A 50-60 KNOT 400-250MB JET. RUC13/NAM12 SHORT-TERM ANALYSIS SHOWS STORMS WILL RAPIDLY DISSIPATE THIS EVENING BY 03Z LEAVING BEHIND SCATTERED MID LEVEL CLOUDS THRU TONIGHT. FRIDAY WILL BE LESS ACTIVE THAN TODAY OVERALL AS THE BEST UPPER DYNAMICS MOVE EAST OF THE AREA. THE SANGRES/NE PLAINS STILL STAND THE BEST CHANCE OF PRECIP FRIDAY AS THE REAR QUADRANT OF TODAYS JET LINGERS OVER THE NE PLAINS. AN UPPER LOW CURRENTLY POSITIONED OFF THE CENTRAL CA COASTLINE GRAZES THE NORTHERN HALF OF THE STATE OVER THE WEEKEND WITH MAINLY ISOLD SHOWERS/STORMS AND SOME AFTERNOON BREEZES. ZONAL FLOW DEVELOPS ACROSS THE SOUTHWEST CONUS INTO EARLY NEXT WEEK BEFORE ANOTHER MORE BROAD TROUGH ESTABLISHES ITSELF OVER THE WESTERN CONUS BY MIDWEEK. MAX/MIN TEMPERATURES WILL BE NEAR CLIMO THRU THE ENTIRE PERIOD. GUYER .AVIATION... VFR CONDITIONS MOST AREAS ACROSS NORTH AND CENTRAL NM THE NEXT 24 HOURS AND BEYOND. THE EXCEPTION WILL BE OVER AND TO THE SOUTHEAST OF THE NORTHERN AND WESTERN MOUNTAINS WHERE ISOLATED TO WIDELY SCATTERED THUNDERSTORMS WILL PRODUCE SOME LOCAL MVFR CEILINGS... MAINLY OVER THE HIGHER TERRAIN. THESE THUNDERSTORMS WILL ALSO PRODUCE GUSTY OUTFLOWS WITH WIND GUSTS OF 25 TO 35 MPH. LOOK FOR CONVECTION TO END BY O3Z...HOWEVER...SOME LOCAL AREAS OF VALLEY FOG ARE POSSIBLE ACROSS THE NORTHERN MOUNTAINS OVERNIGHT...BETWEEN 06Z AND 12Z. WITH UPPER LEVEL RIDGING MOVING OVER THE FORECAST AREA ON FRIDAY...FEWER AFTERNOON THUNDERSTORMS ARE EXPECTED...WITH ISOLATED HIGH BASED STORMS LIMITED TO THE HIGH TERRAIN OF NORTHERN AND WESTERN NEW MEXICO AFTER 18Z AND VFR CONDITIONS PREVAILING MOST AREAS. NEXT AVIATION DISCUSSION SCHEDULED FOR 09Z. 05 .FIRE WEATHER... ISOLATED TO WIDELY SCATTERED THUNDERSTORMS WILL MAINLY PRODUCE GUSTY SURFACE WINDS THIS AFTERNOON AND EVENING...MAINLY OVER AND TO THE EAST OF HIGH TERRAIN. OVERNIGHT RH RECOVERIES ACROSS THE HIGH TERRAIN AREAS WILL BE EXCELLENT OVERNIGHT...WITH GOOD TO VERY GOOD RECOVERIES ELSEWHERE. UPPER LEVEL HIGH PRESSURE BUILDS OVER THE AREA ON FRIDAY WITH A REDUCTION IN THUNDERSTORMS RESULTING. STILL...EXPECT ISOLATED HIGH BASED THUNDERSTORMS MAINLY OVER THE HIGH TERRAIN OF WESTERN AND NORTHERN NM. SIMILAR CONDITIONS ON SATURDAY WITH DRYING ACROSS WESTERN PORTIONS OF THE STATE AND STORMS LIMITED TO THE NORTHERN MOUNTAINS. AN UPPER TROUGH IS FORECAST TO CROSS THE ROCKIES SUNDAY PRODUCING AN INCREASE IN WINDS SUNDAY THROUGH TUESDAY MAINLY ACROSS THE NORTH AND HIGHER TERRAIN. AT THIS TIME CONDITIONS ARE EXPECTED TO REMAIN BELOW CRITICAL THRESHOLDS. 05 && .PRELIMINARY POINT TEMPS/POPS UPDATE... FARMINGTON...................... 46 80 48 81 / 5 5 5 5 GALLUP.......................... 39 78 39 80 / 5 5 5 5 GRANTS.......................... 41 79 41 81 / 5 5 5 5 GLENWOOD........................ 46 80 47 83 / 5 5 5 0 CHAMA........................... 35 72 38 74 / 5 10 10 10 LOS ALAMOS...................... 46 73 47 72 / 10 5 10 10 RED RIVER....................... 32 68 35 69 / 10 20 20 20 TAOS............................ 41 75 42 73 / 10 10 10 10 SANTA FE........................ 47 75 47 74 / 10 10 20 5 SANTA FE AIRPORT................ 46 77 46 76 / 10 5 10 5 ESPANOLA........................ 42 80 44 79 / 10 0 10 0 ALBUQUERQUE HEIGHTS............. 55 79 56 79 / 10 0 5 5 ALBUQUERQUE VALLEY.............. 46 81 51 81 / 10 0 5 0 ALBUQUERQUE FOOTHILLS........... 52 77 50 78 / 10 5 10 5 ALBUQUERQUE WEST MESA........... 48 81 51 81 / 10 0 5 5 SOCORRO......................... 48 83 51 83 / 10 0 10 5 SANDIA PARK/CEDAR CREST......... 40 73 42 72 / 10 5 10 10 MORIARTY/ESTANCIA............... 40 77 48 77 / 10 5 10 10 CARRIZOZO....................... 47 78 50 80 / 5 0 10 0 RUIDOSO......................... 40 72 43 71 / 5 5 20 10 RATON........................... 43 77 43 75 / 10 10 10 10 LAS VEGAS....................... 46 71 44 73 / 10 20 20 10 ROY............................. 48 75 48 76 / 10 10 10 5 CLAYTON......................... 51 79 52 79 / 10 10 10 5 SANTA ROSA...................... 53 81 52 82 / 10 5 10 0 TUCUMCARI....................... 54 83 54 84 / 10 5 10 5 FORT SUMNER..................... 49 82 50 83 / 5 5 10 5 CLOVIS.......................... 51 80 53 80 / 5 5 5 0 PORTALES........................ 51 81 52 81 / 0 0 5 0 ROSWELL......................... 51 83 55 85 / 0 0 5 0 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 19 nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 254 PM MDT THU SEP 18 2008 .DISCUSSION... SHOWER AND STORM COVERAGE HAS INCREASED MARKEDLY THIS AFTERNOON OVER MUCH OF THE NORTHERN TWO THIRDS OF THE STATE...IN RESPONSE TO MODEST LOW/MID LEVEL MOISTURE AND A 50-60 KNOT 400-250MB JET. RUC13/NAM12 SHORT-TERM ANALYSIS SHOWS STORMS WILL RAPIDLY DISSIPATE THIS EVENING BY 03Z LEAVING BEHIND SCATTERED MID LEVEL CLOUDS THRU TONIGHT. FRIDAY WILL BE LESS ACTIVE THAN TODAY OVERALL AS THE BEST UPPER DYNAMICS MOVE EAST OF THE AREA. THE SANGRES/NE PLAINS STILL STAND THE BEST CHANCE OF PRECIP FRIDAY AS THE REAR QUADRANT OF TODAYS JET LINGERS OVER THE NE PLAINS. AN UPPER LOW CURRENTLY POSITIONED OFF THE CENTRAL CA COASTLINE GRAZES THE NORTHERN HALF OF THE STATE OVER THE WEEKEND WITH MAINLY ISOLD SHOWERS/STORMS AND SOME AFTERNOON BREEZES. ZONAL FLOW DEVELOPS ACROSS THE SOUTHWEST CONUS INTO EARLY NEXT WEEK BEFORE ANOTHER MORE BROAD TROUGH ESTABLISHES ITSELF OVER THE WESTERN CONUS BY MIDWEEK. MAX/MIN TEMPERATURES WILL BE NEAR CLIMO THRU THE ENTIRE PERIOD. GUYER && .AVIATION... VFR CONDITIONS MOST AREAS ACROSS NORTH AND CENTRAL NM THE NEXT 24 HOURS AND BEYOND. THE EXCEPTION WILL BE OVER AND TO THE SOUTHEAST OF THE NORTHERN AND WESTERN MOUNTAINS WHERE ISOLATED TO WIDELY SCATTERED THUNDERSTORMS WILL PRODUCE SOME LOCAL MVFR CEILINGS... MAINLY OVER THE HIGHER TERRAIN. THESE THUNDERSTORMS WILL ALSO PRODUCE GUSTY OUTFLOWS WITH WIND GUSTS OF 25 TO 35 MPH. LOOK FOR CONVECTION TO END BY O3Z...HOWEVER...SOME LOCAL AREAS OF VALLEY FOG ARE POSSIBLE ACROSS THE NORTHERN MOUNTAINS OVERNIGHT...BETWEEN 06Z AND 12Z. WITH UPPER LEVEL RIDGING MOVING OVER THE FORECAST AREA ON FRIDAY...FEWER AFTERNOON THUNDERSTORMS ARE EXPECTED...WITH ISOLATED HIGH BASED STORMS LIMITED TO THE HIGH TERRAIN OF NORTHERN AND WESTERN NEW MEXICO AFTER 18Z AND VFR CONDITIONS PREVAILING MOST AREAS. NEXT AVIATION DISCUSSION SCHEDULED FOR 09Z. 05 && .FIRE WEATHER... ISOLATED TO WIDELY SCATTERED THUNDERSTORMS WILL MAINLY PRODUCE GUSTY SURFACE WINDS THIS AFTERNOON AND EVENING...MAINLY OVER AND TO THE EAST OF HIGH TERRAIN. OVERNIGHT RH RECOVERIES ACROSS THE HIGH TERRAIN AREAS WILL BE EXCELLENT OVERNIGHT...WITH GOOD TO VERY GOOD RECOVERIES ELSEWHERE. UPPER LEVEL HIGH PRESSURE BUILDS OVER THE AREA ON FRIDAY WITH A REDUCTION IN THUNDERSTORMS RESULTING. STILL...EXPECT ISOLATED HIGH BASED THUNDERSTORMS MAINLY OVER THE HIGH TERRAIN OF WESTERN AND NORTHERN NM. SIMILAR CONDITIONS ON SATURDAY WITH DRYING ACROSS WESTERN PORTIONS OF THE STATE AND STORMS LIMITED TO THE NORTHERN MOUNTAINS. AN UPPER TROUGH IS FORECAST TO CROSS THE ROCKIES SUNDAY PRODUCING AN INCREASE IN WINDS SUNDAY THROUGH TUESDAY MAINLY ACROSS THE NORTH AND HIGHER TERRAIN. AT THIS TIME CONDITIONS ARE EXPECTED TO REMAIN BELOW CRITICAL THRESHOLDS. 05 && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 47 80 48 81 / 10 5 5 5 GALLUP.......................... 39 78 39 80 / 10 5 5 5 GRANTS.......................... 43 79 41 81 / 10 5 5 5 GLENWOOD........................ 46 80 47 83 / 10 5 5 0 CHAMA........................... 35 72 38 74 / 10 10 10 10 LOS ALAMOS...................... 46 73 47 72 / 10 5 10 10 RED RIVER....................... 32 68 35 69 / 20 20 20 20 TAOS............................ 41 75 42 73 / 10 10 10 10 SANTA FE........................ 47 75 47 74 / 20 10 20 5 SANTA FE AIRPORT................ 46 77 46 76 / 10 5 10 5 ESPANOLA........................ 42 80 44 79 / 10 0 10 0 ALBUQUERQUE HEIGHTS............. 55 79 56 79 / 10 0 5 5 ALBUQUERQUE VALLEY.............. 48 81 51 81 / 10 0 5 0 ALBUQUERQUE FOOTHILLS........... 52 77 50 78 / 20 5 10 5 ALBUQUERQUE WEST MESA........... 50 81 51 81 / 10 0 5 5 SOCORRO......................... 48 83 51 83 / 10 0 10 5 SANDIA PARK/CEDAR CREST......... 40 73 42 72 / 20 5 10 10 MORIARTY/ESTANCIA............... 44 77 48 77 / 20 5 10 10 CARRIZOZO....................... 48 78 50 80 / 10 0 10 0 RUIDOSO......................... 43 72 43 71 / 10 5 20 10 RATON........................... 43 77 43 75 / 10 10 10 10 LAS VEGAS....................... 46 71 44 73 / 20 20 20 10 ROY............................. 48 75 48 76 / 20 10 10 5 CLAYTON......................... 51 79 52 79 / 10 10 10 5 SANTA ROSA...................... 53 81 52 82 / 20 5 10 0 TUCUMCARI....................... 54 83 54 84 / 10 5 10 5 FORT SUMNER..................... 49 82 50 83 / 10 5 10 5 CLOVIS.......................... 51 80 53 80 / 0 5 5 0 PORTALES........................ 51 81 52 81 / 0 0 5 0 ROSWELL......................... 51 83 55 85 / 0 0 5 0 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ GUYER/05 nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 929 AM MDT THU SEP 18 2008 .UPDATE... A 50 KNOT UPPER LEVEL JET SLIDING SE ACROSS THE REGION TODAY.. COMBINED WITH MODEST LOW/MID LEVEL MOISTURE...WILL ALLOW NW FLOW PATTERN STORMS TO FIRE ALONG THE SANGRE DE CRISTOS. RAISED POPS TO SCATTERED ALONG AND TO THE LEE OF THE SANGRES PER LATEST RUC13 AND 12Z NAM GUIDANCE. STORMS SHOULD DISSIPATE QUICKLY ACROSS THE REGION AFTER SUNSET. GUYER && .PREV DISCUSSION...300 AM MDT THU SEP 18 2008... CURRENTLY...SHORTWAVE TROUGH SWEEPING THROUGH NORTHEAST NEW MEXICO EMBEDDED IN BROADLY ZONAL FLOW. CLOCKSPRING CLOSED LOW ALOFT OFF THE COLUMBIA RIVER ESTUARY WILL HELP PUMP UP ADVANCE RIDGE OVER NEW MEXICO HEADING INTO THE WEEKEND. SURFACE CHARTS PAINTING RIDGE OVER EASTERN END OF THE STATE WITH WEAK SURFACE TROUGH CENTERED OVER LOWER COLORADO RIVER VALLEY...BROADLY SETTING UP SOUTHERLY FLOW ACROSS THE STATE. MODELS...GOOD CONSENSUS MOVING CLOSED LOW INTO NORTHERN CALIFORNIA ON FRIDAY...AND SHEARING IT RAPIDLY EASTWARD INTO THE NORTHERN PLAINS BY LATE IN THE WEEKEND. PATH WILL KEEP MOST ALL SERIOUS ENERGY NORTH OF NEW MEXICO AS ZONAL FLOW RETURNS ACROSS THE STATE BY LATE IN THE WEEKEND. NEXT TROUGH AMPLIFYING ALONG THE WEST COAST SUNDAY AFTERNOON WILL SWING TO THE FOUR CORNERS MONDAY AFTERNOON AND DRIFT SLOWLY EASTWARD THROUGH THE FIRST HALF OF THE UPCOMING WORK WEEK. SHORT TERM...TODAY AND TONIGHT...NEARLY ZONAL FLOW ALOFT WITH SURFACE TROUGH BUDGING EASTWARD INTO WESTERN NEW MEXICO WILL MAINTAIN SOUTHERLY FLOW OVER MUCH OF THE STATE THROUGH THE DAY WITH TEMPERATURES WORKING A DEGREE OR TWO ABOVE SEASONAL NORMS. MOSTLY ISOLATED CONVECTION ON THE DAY...WITH FAVORED TOPOGRAPHY MAINLY IN THE SOUTHWEST MOUNTAINS...AND THE NORTHERN MOUNTAINS. PWATS EASING UP TOWARD A HALF INCH WITH VERY MODEST INSTABILITY ON THE DAY MAY BE ENOUGH TO MAINTAIN A FEW ISOLATED SHOWERS OVER THE NORTHEAST HIGHLANDS TO WIND UP THE EVENING. LONG TERM...FRIDAY THROUGH SUNDAY...RIDGE BUILDING ALOFT IN ADVANCE OF NORTHEAST PACIFIC SYSTEM WILL KEEP SKIES BROADLY CLEAR ON FRIDAY...AND HELP BOOST TEMPERATURES ANOTHER DEGREE OR TWO ABOVE NORMAL IN BROAD SOUTH FLOW. EXPECTING FURTHER REDUCTIONS IN ISOLATED SHOWER AND THUNDERSTORM COVERAGE...WITH FAVORED TERRAIN IN THE SOUTHWEST MOUNTAINS AND NORTHERN HIGHLANDS A GOOD BET FOR SPOTTY THUNDERSTORM INITIATION. INTO SATURDAY...RIDGE AXIS EXTENDING FROM BAJA CALIFORNIA ACROSS NEW MEXICO TO WESTERN KANSAS WITH SURFACE TROUGH DEEPENING ALONG THE ARIZONA BORDER WILL MAINTAIN SOUTHERLY FLOW STATEWIDE...AND ANOTHER DAY OF SLIGHTLY WARMER THAN NORMAL TEMPERATURES AND CONVECTION ALONG FAVORED PORTIONS OF THE NORTHERN MOUNTAINS IS ON TAP. ENERGY FROM SHEARING WEATHER SYSTEM TO THE NORTH WILL MAKE THE CLOSEST SCRAPE OF NORTHERN NEW MEXICO SATURDAY EVENING...AND THIS MAY PROLONG ANY INITIATED CONVECTION LATE IN THE DAY. INTO SUNDAY...RIDGE TOP SHEARING RAPIDLY EASTWARD AS MORE ENERGETIC ZONAL FLOW SETS IN ALOFT IN ADVANCE OF AMPLIFYING TROUGH DOWN THE WEST COAST. SOUTH AND SOUTHWEST FLOW PUSHING OVER THE STATE WILL BROADEN ISOLATED CONVECTION DURING THE DAY OVER THE USUAL SPOTS...THE NORTHERN MOUNTAINS AND PORTIONS OF THE CENTRAL MOUNTAIN CHAIN. LITTLE CHANGE TO THE TEMPERATURE REGIME TO WIND UP THE WORK WEEK. SHY .AVIATION... VFR CONDITIONS AGAIN PREVAILING ACROSS NORTH AND CENTRAL NM THE NEXT 24 HOURS AND BEYOND. BUT AFTERNOON AND EVENING HIGH BASED ISOLATED SHOWERS AND THUNDERSTORMS WILL AGAIN DEVELOP ACROSS THE NORTHWEST HALF TO TWO THIRDS OF THE STATE TODAY WITH THE NORTHERN AND WEST CENTRAL HIGHER TERRAIN FAVORED SOMEWHAT. A FEW MAY MANAGE TO SURVIVE LONG ENOUGH TO DRIFT OVER THE NORTHEAST AND POSSIBLY EAST CENTRAL PLAINS. WIND GUSTS BETWEEN 25 AND 40 KNOTS ARE LIKELY NEAR THE MORE SIGNIFICANT SHOWERS AND STORMS. ISOLATED THUNDERSTORMS MAY DEVELOP AGAIN FRIDAY AFTERNOON FIRST OVER THE MOUNTAINS WITH A FEW SURVIVING INTO THE PLAINS. NEXT AVIATION DISCUSSION SCHEDULED FOR 21Z. 43 .FIRE WEATHER... ISOLATED VIRGA SHOWERS AND MAINLY DRY THUNDERSTORMS THIS AFTERNOON AND EVENING WILL FAVOR THE HIGHER TERRAIN WITH JUST A FEW SURVIVING LONG ENOUGH TO DRIFT OVER THE NORTHEAST AND POSSIBLY EAST CENTRAL PLAINS. AFTERNOON AND EVENING ISOLATED VIRGA SHOWERS AND MOSTLY DRY THUNDERSTORMS ARE POSSIBLE THROUGH SATURDAY WITH MINIMUM HUMIDITIES BELOW 20 OR 25 PERCENT IN MOST AREAS AND FAIR TO GOOD OR VERY GOOD NIGHTTIME RECOVERIES. UPPER TROUGH CROSSING THE ROCKIES SUNDAY MAY DROP THE WESTERLIES SOUTH FAR ENOUGH TO INCREASE WINDS SOMEWHAT SUNDAY THROUGH TUE OR SO OVER THE NORTH AND HIGHER TERRAIN...THOUGH GENERALLY BELOW CRITICAL THRESHOLDS. 43 && .PRELIMINARY POINT TEMPS/POPS UPDATE... FARMINGTON...................... 82 51 83 51 / 5 0 5 5 GALLUP.......................... 77 43 78 43 / 10 10 5 5 GRANTS.......................... 78 42 79 43 / 10 10 5 5 GLENWOOD........................ 82 55 84 51 / 20 20 5 5 CHAMA........................... 71 36 72 35 / 10 5 5 5 LOS ALAMOS...................... 73 46 75 45 / 20 20 5 5 RED RIVER....................... 66 33 67 31 / 30 10 10 5 TAOS............................ 74 39 75 39 / 20 10 5 5 SANTA FE........................ 75 47 77 48 / 10 5 5 5 SANTA FE AIRPORT................ 78 48 79 48 / 10 10 5 0 ESPANOLA........................ 81 44 82 44 / 10 10 5 5 ALBUQUERQUE HEIGHTS............. 81 56 82 55 / 5 5 0 0 ALBUQUERQUE VALLEY.............. 82 49 82 50 / 5 5 0 0 ALBUQUERQUE FOOTHILLS........... 78 53 78 52 / 5 5 0 0 ALBUQUERQUE WEST MESA........... 80 55 81 55 / 5 5 0 0 SOCORRO......................... 81 49 83 51 / 5 5 0 0 SANDIA PARK/CEDAR CREST......... 72 41 73 42 / 10 5 0 5 MORIARTY/ESTANCIA............... 77 43 78 44 / 5 5 5 0 CARRIZOZO....................... 79 47 80 49 / 0 0 5 0 RUIDOSO......................... 71 42 72 43 / 5 0 5 0 RATON........................... 78 42 78 42 / 20 20 10 5 LAS VEGAS....................... 75 44 75 43 / 30 20 10 5 ROY............................. 75 49 77 50 / 20 20 10 5 CLAYTON......................... 80 50 79 51 / 10 10 5 5 SANTA ROSA...................... 83 50 83 49 / 10 20 5 0 TUCUMCARI....................... 84 52 83 54 / 10 10 0 0 FORT SUMNER..................... 83 51 83 52 / 5 10 0 0 CLOVIS.......................... 80 52 81 53 / 5 0 0 0 PORTALES........................ 81 51 82 54 / 5 0 0 0 ROSWELL......................... 84 54 85 55 / 0 0 0 0 && .ABQ WATCHES/WARNINGS/ADVISORIES... NONE. && $$ GUYER nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 153 PM EDT FRI SEP 19 2008 .SYNOPSIS... HIGH PRESSURE ACROSS THE NORTHEAST WILL RIDGE INTO THE CAROLINAS THROUGH THE WEEKEND AND BRING COOLER THAN NORMAL TEMPERATURES TO THE REGION. A TROUGH OF LOW PRESSURE WILL DEVELOP OFFSHORE AND MOVE JUST CLOSE ENOUGH TO THE AREA TO INCREASE THE CHANCE OF SHOWERS LATE IN THE WEEKEND AND INTO EARLY NEXT WEEK...MAINLY ALONG THE COASTAL COUNTIES. && .NEAR TERM /THROUGH TONIGHT/... AS OF 9 AM FRIDAY...BREEZY NORTHEAST WINDS THIS AFTERNOON ARE THE RESULT OF A PRESSURE GRADIENT BETWEEN A HIGH CENTERED OVER MAINE AND A FRONTAL BOUNDARY WELL OFF THE COAST. ANOTHER RAIN FREE DAY OVER LAND IS FORECAST AS MOISTURE CONTINUES TO BE LIMITED. MORNING SOUNDINGS ALSO SHOW AN INVERSION AROUND 825 MB FROM THE HIGH PRESSURE RIDGE. THIS IS CONFIRMED BY THE 12 UTC RUC WHICH SHOWS AROUND 90 PERCENT OF THE AREA BEING STABLE. THE ONLY AREA THAT SHOWS ANY INSTABILITY THIS AFTERNOON BEING EASTERN BRUNSWICK AND NEW HANOVER COUNTY. WITH THE CAP AT 825 MB DO NOT EXPECT ANY PRECIPITATION OVER THIS AREA THIS AFTERNOON JUST SOME CONVECTIVE ROLES. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...STILL EXPECTING A COOL AND RELATIVELY DRY WEEKEND AS HIGH PRESSURE ANCHORED TO THE NORTH AND AN OLD FRONT AND LOW PRESSURE TO THE EAST WILL BE THE MAIN PLAYERS. THE GFS HAS TRENDED A LITTLE DRIER WITH THE QPF...WHICH WASNT OVERLY IMPRESSIVE IN THE FIRST PLACE AS THE SHIELD HAS JOGGED TO THE EAST. THE FLOW HAS BACKED TO A MORE NORTHERLY DIRECTION AS WELL PROBABLY DUE TO A WEAK CLOSED CIRCULATION DEVELOPING OVER THE GULF STREAM. ALL OF THIS SAID...HAVE TRIMMED POPS BACK EVER SO SLIGHTLY TO REPRESENT THIS TREND...MAINLY CONFINING THEM TO THE COASTAL COUNTIES WITH THE EXCEPTION OF LATE SATURDAY INTO SUNDAY MORNING WHEN A FEW SPRINKLES COULD MIGRATE INLAND. SOME SIGNIFICANT DIFFERENCES REGARDING THE TEMPERATURE GUIDANCE FOR THE PERIOD WITH THE MET NUMBERS A CATEGORY COOLER IN SOME INSTANCES. A FEW WEEKS AGO DURING THE HEAT OF THE SUMMER THE SOLUTION WOULD BE SIMPLE...GO WITH THE MET. WITH THE FALL QUICKLY APPROACHING AND THE FACT THE MAV NUMBERS HAVE BEEN BETTER AT LEAST DURING THE INITIAL STAGES OF THIS AIR MASS THE SOLUTION IS A BIT MORE COMPLEX. WILL UNDERCUT THE MAV NUMBERS A DEGREE OR TWO AS THE MET NUMBERS JUST SEEM TOO COOL. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 3 AM FRIDAY...STILL A LOT OF UNCERTAINTY REGARDING THE POSSIBLE DEVELOPMENT OF LOW PRESSURE OFF THE COAST WHICH WILL BE THE FOCUS OF THE EXTENDED OR MORE SPECIFICALLY THE LATTER HALF OF THE EXTENDED...FROM WEDNESDAY ON. THE LATEST OPERATIONAL GFS HAS SHIFTED THE LOW PRESSURE TO THE SOUTH AND EAST. THE ENSEMBLE MEMBERS SEEM TO HAVE SOMETHING FOR EVERYONE...WITH LOW PRESSURE FROM THE BAHAMAS ALL THE WAY TO THE NORTH JUST EAST OF HATTERAS. OBVIOUSLY THERE IS STILL NOTHING TO HANG OUR HATS ON AND I SUSPECT IT WILL REMAIN SO FOR THE NEXT FEW DAYS. I TRIMMED BACK POPS AND CLOUD COVER SLIGHTLY TO REPRESENT A TREND IF NOTHING ELSE BUT CONFIDENCE IN LOWER THAN USUAL IN THE EXTENDED. && .AVIATION /18Z FRIDAY THROUGH TUESDAY/... AVIATION PROBLEMS WILL BE WITH GUSTING WINDS AT THE COASTAL TAFS WITH GUST EXPECTED TO REACH AROUND 25 KNOTS TONIGHT . ALSO...MODELS ARE INDICATING LIFR/IFR STRATUS ALONG THE COAST AFTER 09 UTC. BUFR SOUNDINGS ARE SHOWING STRATUS LAYER A BIT HIGHER IN THE MVFR RANGE AT THE SAME TIME. SO HAVE FAVORED BUFR SOUNDINGS OVER THE NUMERICAL GUIDANCE. OUTLOOK THROUGH MONDAY...WITH TROUGH OF LOW PRESSURE AND MODELS STILL NOT HONING IN ON A SIMILAR SOLUTION THERE CONTINUES TO BE HIGHER THAN NORMAL UNCERTAINTY IN THIS PERIOD. CONDITIONS WILL DRIVEN BY THE LOCATION AND TIMING OF THE LOW PRESSURE CENTERS THAT TRANSVERSE THE OFFSHORE BOUNDARY AND THE DISTANCE TO THE TAFS SITES. THE INLAND TAF SITES WILL GENERALLY BE VFR WHILE COASTAL SITES HAVE A BETTER CHANCE OF SEEING SHOWERS AND LOWER CEILING. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF NOON FRIDAY...A TIGHT PRESSURE GRADIENT RESULTING FROM HIGH PRESSURE OVER MAINE AND AN OLD FRONT OFF THE COAST IS PRODUCING STRONG NORTHEAST WINDS. AT NOON FRYING PAN WAS REPORTING NORTHEAST WINDS OF 27 KNOTS AND SEAS OF 8.5 FEET. CLOSE TO THE COAST SEAS 4 TO 5 FEET WERE BEING OBSERVED. AS THE PRESSURE GRADIENT CONTINUE THROUGH TONIGHT SEAS AND WINDS WILL REMAIN HIGH AND SMALL CRAFT CONDITIONS WILL CONTINUE INTO SATURDAY. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 AM FRIDAY...A NORTH TO NORTHEAST FLOW WILL PREVAIL THROUGH THE PERIOD. THE DILEMMA IS WHAT WILL BE THE MAGNITUDE OF THE FLOW AS THE NAM/WRF IS MUCH STRONGER WITH THE GRADIENT DUE TO THE CLOSED LOW OVER THE GULF STREAM BEING DEEPER. THERE IS A GOOD 10 TO 12 KNOTS DIFFERENCE IN THE MARINE GUIDANCE FOR 41013 WHEN COMPARING THE NAM AND MAV BULLETINS. I LIKE THE GFS BUT CANT DISREGARD THE NAM COMPLETELY AND WILL INCREASE THE GFS WINDS ANS SEAS A BIT ACROSS THE BOARD. WITH THIS IN MIND...EXPECT SMALL CRAFT CONDITIONS TO CONTINUE SATURDAY AND WILL EXTEND THROUGH THE DAY WITH SUFFICIENT CONFIDENCE. COULD BE A SIMILAR SITUATION SUNDAY AS THE NAM CONTINUES WITH THE ROBUST SOLUTION. FOR NOW HAVE WINDS AND SEAS DROPPING BELOW FLAG CRITERIA BUT SUBSEQUENT SHIFTS WILL HAVE TO MONITOR TRENDS CLOSELY. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 3 AM FRIDAY...NORTHEAST FLOW THROUGH THE PERIOD...MOST LIKELY BELOW FLAG CRITERIA. NO CHANGES TO THE EXTENDED COASTAL WATERS FORECAST THIS MORNING. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT SATURDAY FOR AMZ250-252- 254-256. && $$ SYNOPSIS...SHK NEAR TERM...HAWKINS SHORT TERM...SHK LONG TERM...SHK AVIATION...HAWKINS nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 117 PM EDT THU SEP 18 2008 .SYNOPSIS... A WEAK COLD FRONT WILL CONTINUE TO MOVE SOUTH OF THE AREA THROUGH THE MORNING. SURFACE HIGH PRESSURE WILL BUILD INTO THE REGION TODAY AND THEN MOVE OFF THE NEW ENGLAND COAST LATE FRIDAY. ANOTHER WEAK COLD FRONT WILL MOVE INTO THE LOWER GREAT LAKES LATE SATURDAY INTO SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... COLD FRONT HAS MOVED THROUGH THE FORECAST AREA AND THE WINDS ARE NORTHEAST. BY 12Z THE LAKE AND 850 MB TEMPERATURE DIFFERENCE WILL RANGE FROM 11C WEST TO 13C EXTREME NORTHEAST. WITH A NORTHEAST FLOW IT WILL TRY TO DRY OUT FROM THE NORTHEAST. THE MODELS GENERALLY AGREE ON THAT AND THE NORTHWEST AREAS WILL CONTINUE WITH SOME CLOUDS ALL DAY I.E. PARTLY CLOUDY. A FEW SPRINKLES ACCOMPANIED THE FRONT AS IT MOVED THROUGH OVERNIGHT. THE RUC TRIES TO INDICATE A FEW HUNDREDTHS OF RAIN AROUND 12Z NEAR CLE...THE OTHER MODELS ARE DRY. IT IS POSSIBLE FOR A SPRINKLE BUT WITH THE VORT JUST ABOUT OUT OF THE AREA BY 12Z WILL KEEP IT DRY. NO MOIST ENOUGH OR COLD ENOUGH FOR WATERSPOUTS ON THE LAKE. TEMPERATURE WISE THE GUIDANCE IS ALL ABOUT THE SAME AND THEY MATCH LOCAL SCHEMES..WENT CLOSER TO THE MOS MAV. THE ONLY EXCEPTION WAS OVER THE EXTREME EASTERN PORTION OF THE FORECAST AREA WHERE THE GFS IS MUCH COOLER THAN THE MET WHILE THE NAM MOS IS IN BETWEEN. BASED ON THE WINDS AND CLOUDS WENT CLOSER TO THE MOS MAV BUT A FEW DEGREES WARMER. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... CLEAR SKIES TONIGHT WITH THE HIGH TO THE NORTHEAST. THE QUESTION IS HOW COLD WILL IT GET. THIS MODEL RUN IS A LITTLE WARMER THAN THE 12Z RUN AND IT IS MUCH WARMER THAN THE 00Z RUN (24 HOURS AGO). AT THIS TIME IT DOESN`T SEEM LIKE THE DEW POINTS WILL DROP OFF AS MUCH AS EARLIER THOUGHT...SO THIS MEANS NOT AS COLD. DO LIKE THE GRIDDED MOS WHICH IS A LITTLE COOLER THAN THE NAM/GFS MODEL RUNS...BUT HAVE CONCERNS THAT THERE WILL BE SOME WIND AND ONLY ISOLATED LOW LYING AREAS WILL BE REAL COOL. THE WINDS SHOULD BECOME OFFSHORE SO MOST LOCATIONS NEAR LAKE ERIE WILL ALSO COOL DOWN. AT THIS TIME THE LOWEST READINGS WILL BE IN INLAND NORTHWEST PA IN THE UPPER 30S SO WILL MENTION A CHANCE OF SOME FROST IN LOW LYING AREAS IN PA. THIS WILL HAVE TO BE MONITORED. SUNNY FRIDAY AND MOS MAV LOOKS GOOD. CLEAR FRIDAY NIGHT AND WITH A WEAK GRADIENT I LIKE THE COOLER GRIDDED MOS NUMBERS. ON SATURDAY WITH A SOUTHWEST FLOW AHEAD OF THE WEAK COLD FRONT TO THE NORTH SOME OF THE MOS NUMBERS SEEM TOO COOL BASED ON THE LOCAL SCHEMES USING THE 850 MB TEMPERATURES AND EXPECTING THE FRONT TO STAY NORTH THROUGH THE PERIOD. THE GRIDDED MOS SEEMS BETTER BUT WENT A DEGREE OR SO COOLER FOR TOL AND FDY. WEAK COLD FRONT MOVES THROUGH SATURDAY NIGHT ACCORDING TO THE GFS AND ECMWF WHILE THE NAM IS SLOWER. AT THIS TIME WITH LIMITED MOISTURE WILL KEEP IT DRY BUT NEXT SHIFTS WILL HAVE TO KEEP AN EYE ON IT. WENT WITH A LITTLE WARMER LOWS WITH SOME CLOUDS AROUND. AT THIS TIME WILL CONTINUE THE 20 POPS FOR SUNDAY. MODEL CONFLICT... GFS HAS IT DRY WITH THE FRONT TO THE SOUTH OF THE AREA...WHILE THE NAM AND ECMWF STILL HAVE SOME MOISTURE AND THE UPPER TROF ON SUNDAY. NO CHANGES UNTIL THINGS ARE CLEAR. DRY SUNDAY NIGHT WITH RIDGE BUILDING ALOFT AND RIDGE BUILDING IN FROM THE WEST. THE MEX NUMBERS FOR HIGHS ON SUNDAY LOOK GOOD AND WENT COOL FOR SUNDAY NIGHT BECAUSE OF SOMEWHAT LIGHT WINDS AND MOSTLY CLEAR SKIES. && .LONG TERM /MONDAY THROUGH THURSDAY/... BOTH THE ECMWF AND THE ENSEMBLE IN AGREEMENT WITH UPPER RIDGE ACROSS THE LOWER LAKES THROUGH THE FORECAST PERIOD. EXPECT DRY CONDITIONS AND NEAR SEASONAL TEMPS. && .AVIATION /17Z THURSDAY THROUGH MONDAY/... SURFACE HIGH PRESSURE WILL GRADUALLY SLIDE EASTWARD THROUGH THE NIGHT WITH WINDS GRADUALLY SWINGING AROUND TO THE EAST. LAKE CLOUDS WILL CONTINUE TO DISSIPATE THROUGH THE AFTERNOON FOR LOCATIONS EAST OF A CLE TO CAK LINE AS DRIER AIR CONTINUES TO SPILL INTO NORTHERN OHIO. NORTHEASTERLY WINDS WILL BE A BIT GUSTY THROUGH THE AFTERNOON BUT EXPECT THEM TO DECREASE DURING THE EVENING. OUTLOOK...VFR CONDITIONS EXPECTED FRIDAY AND SATURDAY. COULD SEE A FEW SHOWERS AND AT LEAST BRIEF MVFR CONDITIONS MAY OCCUR SUNDAY MORNING AS NEXT FRONT MOVES ACROSS THE AREA. VFR CONDITIONS RETURN MONDAY AS HIGH PRESSURE BUILDS BACK INTO AREA. && .MARINE... SCA WILL REMAIN IN EFFECT FOR ENTIRE LAKE THROUGH THE AFTERNOON HOURS. AFTER THAT WINDS WILL DROP BELOW SCA CRITERIA...BUT LAKE WILL REMAIN CHOPPY WITH NE FLOW AND 2 TO 4 FOOT WAVES. FOLLOWING THE FRONT...HIGH PRESSURE WILL REMAIN OVER THE LAKE THROUGH SUNDAY. ANOTHER WEAK FRONT WILL CROSS THE LAKE SUNDAY AND MUCH LIKE TONIGHT...WILL BRING WINDS AROUND OUT OF THE NORTHEAST. THIS FRONT DOES NOT LOOK TERRIBLY IMPRESSIVE BUT SMALL CRAFT WINDS/WAVES COULD STILL BE A POSSIBILITY. HIGH PRESSURE ONCE AGAIN SETTLES OVERHEAD ON MONDAY. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR LEZ142>149. && $$ SYNOPSIS...KIELTYKA NEAR TERM...OUDEMAN SHORT TERM...KIELTYKA LONG TERM...DJB AVIATION...MULLEN MARINE...DJB oh AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 1115 AM CDT FRI SEP 19 2008 .DISCUSSION... MINIMAL ELEVATED TSRA CHANCE IS ONLY REAL CONCERN TODAY...AS GOING FORECAST ALREADY HAS A GOOD HANDLE ON GUSTY SOUTHERLY WINDS AND TEMPS STILL LOOKING GOOD THUS FAR. MID LEVEL LAPSE RATES FAVORABLE ACROSS THE NORTHWEST 1/2 OF THE CWA DURING THE LATE AFTERNOON AND OVERNIGHT...BUT BOTH NAM AND RUC SHOW LIMITED MOISTURE AVAILABLE TO SUPPORT EVEN ISOLATED TSRA IN THIS AREA. BAND OF SOMEWHAT BETTER MOISTURE SLIDES SOUTHEAST ACCOMPANYING WEAK BOUNDARY...BUT MOVING INTO LESS FAVORABLE AREA OF MID LEVEL INSTABILITY AS THE NIGHT PROGRESSES. HAVE REMOVED MENTION OF ISOLATED TSRA FROM THE FAR NORTHWEST CWA FOR THE LATE AFTERNOON...AND WILL SEND UPDATED ZFP FOR THAT SHORTLY. WILL HANG ONTO OVERNIGHT MENTION FOR NOW...BUT WILL REEVALUATE BEFORE REGULAR ZFP ISSUANCE THIS AFTERNOON. && .AVIATION... VFR CONDITIONS EXPECTED TO PERSIST THRU 12Z SAT. ISOLATED TSRA POSSIBLE NEAR BOUNDARY AS IT SAGS SOUTHEAST THROUGH THE AREA LATE THIS AFTERNOON AND TONIGHT. HOWEVER...MOISTURE LIMITED AND BOUNDARY WORKING INTO AREA OF LESS FAVORABLE MID LEVEL LAPSE RATES AS THE NIGHT PROGRESSES. WL KEEP MENTION OF TSRA OUT OF TAFS DUE TO VERY LOW LIKELIHOOD. && .PREV DISCUSSION... BRISK SLY FLOW BRINGING UP A MODICUM OF MOISTURE WITH IT TDA... COMPARED TO YESTERDAYS RELATIVELY DRY DEWPOINTS TO THE SOUTH. FNTL BOUNDARY FM NE TO SW SD HAS ALREADY PRODUCED A FEW TSTMS...WHICH MAY GRAZE THE FAR NRN CWA THIS MRNG. HOWEVER...AS BOUNDARY MOVES SE AND AIR MASS HEATS OUT THIS AFTN...AT LEAST ISOLD TSTMS SHOULD REDVLP FM WRN TO NRN PTNS OF THE CWA...MOVG SEWD OVR CWA TNGT BEFORE FALLING APART LATE. DEEP VEERING WIND PROFILE AND STEEP LAPSE RATES ARE A CONCERN FOR EVEN AN ISOLD SVR STORM THIS AFTN INTO EARLY EVE. ONLY DRAWBACK IS WEAK DYNAMICS AND MOISTURE SUPPLY. FNT WILL SAG SEWD OVR CWA TNGT BEFORE RETURNING SLOWLY NWD AS A WMFNT THIS WEEKEND...WITH SOME BACKDOOR COOLING EXPCD NERN HLF CWA. SSELY FLOW SHOULD REALLY KICK IN BY SUN AFTN...BRINGING BACK BTR MOISTURE SUN NGT THRU EARLY NEXT WEEK AHEAD OF DVLPG BROAD UPR TROF PUNCHING EWD FM RCKYS. UPPD POPS SOME WITH FIRST GOOD WAVE SHOWN ON ALL MODELS MOVG EWD OVR CWA FM SUN NGT THRU MON. GETS A LITTLE FUZZY AFT THAT WITH STILL SOME SIGN OF REDVLPMT MON NGT AND TUE WITH INCRG MOISTURE AND DYNAMICS. HOWEVER...TUE NGT STILL LOOKS LIKE THE MAIN CHC TSTMS MOVG EWD WITH CDFNT...AND MASSAGED UP THE POPS SOME. THIS SYSTEM HAS THE POTENTIAL TO FINALLY PROVIDE SOME NEEDED SIGNIFICANT PRECIP IN THE AREA. GFS MOVES EVERYTHING THRU BY WED...BUT ECMWF STILL HAS A HANGBACK CHC TSTMS AS PER PREV FCST INTO WED. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ JH sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 950 PM CDT THU SEP 18 2008 .UPDATE... LOW PRESSURE AND ASSOCIATED SFC TROF CURRENTLY ALONG THE MO RIVER...WITH SCT -TSRA DEVELOPING EAST OF KBIS IN ND. LATEST RUC ADVERTISES 85H WINDS TO INCREASE TO 30 TO 40 KTS OVERNIGHT ACROSS THE EAST. WITH MINOR 7H OMEGA OCCURRING...CANT ARGUE AGAINST THE ISOLD/SLGT CHC POPS CURRENTLY IN FCST. FOR NOW...CURRENT GRIDS ARE IN FINE SHAPE WITH ONLY HOURLY TWEAKS REQUIRED. NO ZONE FORECAST PACKAGE UPDATE PLANNED ATTM. UPDATED AVIATION DISCUSSION BELOW. && .PREV DISCUSSION... .SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT THE MAIN CHALLENGE IN THE NEAR TERM IS PRECIPITATION CHANCES TONIGHT. A WEAK UPPER LEVEL TROUGH WILL TRACK ACROSS THE PLAINS TONIGHT AND FRIDAY AHEAD OF A RIDGE SETTING UP OVER THE ROCKIES. WEAK PVA WILL BE OVER THE NORTHERN CWA TONIGHT. A SURFACE TROUGH CURRENTLY LOCATED FROM LAKE WINNIPEG TO EASTERN COLORADO WILL ALSO SLOWLY APPROACH THE REGION. AHEAD OF THIS TROUGH...A 20 TO 35 KNOT LLJ WILL DEVELOP TONIGHT IN ASSOCIATION WITH 1000-1500 J/KG OF CAPE AND LIS IN THE -2 TO -5 RANGE. TWO LIMITING FACTORS WILL BE 700 MB TEMPS AROUND +8 TO +9 AND LIMITED MOISTURE. THEREFORE...WILL JUST KEEP A SMALL POP GOING ACROSS THE NORTHERN CWA CLOSER TO THE UPPER LEVEL ENERGY. IF ANY STORMS DO GET GOING...THEY MAY HAVE THE POTENTIAL TO PRODUCE SOME SMALL HAIL. A COLD FRONT WILL DROP OUT OF CANADA TO NORTHERN NORTH DAKOTA TONIGHT. THIS FRONT REACHES SOUTHERN NORTH DAKOTA BY FRIDAY AFTERNOON...THEN PUSHES TO SOUTHERN SOUTH DAKOTA FRIDAY NIGHT BEFORE STALLING OUT THROUGH THE DAY SATURDAY...THEN PUSHING BACK NORTH AS A WARM FRONT SATURDAY NIGHT AS LOW PRESSURE STRENGTHENS OVER THE NORTHERN ROCKIES. EVEN THOUGH WEAK INSTABILITY REMAINS OVER THE AREA IN ASSOCIATION WITH THE FRONT...MOISTURE WILL CONTINUE TO BE VERY LIMITED THROUGH THE REST OF THE PERIOD...AND HAVE DECIDED TO KEEP THE MENTION OF PRECIPITATION OUT AT THIS TIME. EXPECT ABOVE NORMAL TEMPERATURES TO CONTINUE THROUGH THE PERIOD AS H85 TEMPS REMAIN IN THE MID TEENS TO LOWER 20S. WILL STICK WILL HIGHS MAINLY IN THE 80S AND LOWS IN THE 50S. .LONG TERM...SUNDAY THROUGH THURSDAY THE MAIN CHALLENGE IN THE EXTENDED DEALS WITH PRECIPITATION AS MODELS SHOW A COUPLE OF WAVES PASSING THROUGH THE REGION. THE PERIOD BEGINS WITH AREA OF LOW PRESSURE OVER THE NORTHERN HIGH PLAINS WITH STRONG SOUTHERLY FLOW/WAA UP THE PLAIN STATES. THE SURFACE LOW TAKES ON A BIT OF A NEGATIVE TILT...LEADING TO A SLOWER PROGRESSION. HAVE BACKED PCPN OFF BY SIX HOURS...AND WOULD NOT BE SURPRISED IF PCPN IS REMOVED ALL TOGETHER ON SUNDAY. SUNDAY NIGHT HOWEVER...WITH A STRONG LLJ OF 40KTS AND 25KTS OF 0-1KM BULK SHEAR...HAVE INCREASED POPS SOME ACROSS THE AREA. SURFACE LOW MOVES NNE INTO CENTRAL SASKATCHEWAN ON TUESDAY...WITH THE MID/UPPER LEVEL FLOW PATTERN DE-AMPLIFYING OVER THE REGION. THE MID/UPPER LEVEL TROF AXIS SLOWLY PUSHES EASTWARD ON WEDNESDAY...ENDING PCPN CHANCES. HIGH PRESSURE BUILDS IN THERE AFTER...WITH THE GFS SHOWING WARMER AIR WORKING BACK INTO THE AREA FOR THE NEXT WEEKEND. && .AVIATION... P6SM VSBYS EXPECTED FOR ALL TERMINALS THROUGH 00Z SATURDAY. SCT/BKN130 CLOUDS EXPECTED TO DRIFT EAST ACROSS KMBG/KPIR TERMINALS THROUGH 10Z...AND ACROSS KABR/KATY TERMINALS THROUGH 13Z. ISOLD -TSRA IS PSBL AFT 06Z FOR THE KABR/KATY TERMINALS...BUT CONFIDENCE OF ACTUAL DEVELOPMENT IS LOW...SO LEFT OUT OF TERMINAL FCSTS ATTM. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...HINTZ SHORT TERM...TMT LONG TERM...PARKIN AVIATION...HINTZ WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 936 AM CDT THU SEP 18 2008 .UPDATE...A SPRINKLING OF SHOWERS ARE NOTED SOUTHEAST OF PORT ISABEL AND JUST NORTH OF THE NORTHERN CWA BORDER. RUC40 DEPICTS A FEW WEAK MIDLEVEL SHORTWAVES PASSING ACROSS SOUTH CENTRAL TEXAS THIS MORNING WITH A FEW OTHERS ANTICIPATED THIS AFTERNOON. MOISTURE REMAINS LIMITED WITH PRECIPITABLE WATER VALUES 1.53 INCHES AT BRO...1.25 CRP AND 1.39 INCHES AT DEL RIO. ANY RAIN THAT FALLS IN THE WESTERN ZONES WILL LIKELY NOT REACH THE GROUND AND WITH SHOWERS OFF THE COAST LIKELY TO REMAIN OFF THE COAST. WITH THIS SAID 10 PERCENT POPS CURRENTLY IN THE FORECAST WILL SUFFICE. FORECAST HIGH TEMPERATURES WILL BE WITHIN THE BALLPARK EVEN WITH BRIEFLY THICKER CLOUDS PASSING OVERHEAD. REST OF THE FORECAST LOOKS ON TRACK WITH NO CHANGES NEEDED AT THIS TIME. && .AVIATION...HIGH CLOUDS CONTINUE TO DRIFT ACROSS DEEP SOUTH TEXAS THIS MORNING. WOULD EXPECT THIS FEATURE TO REMAIN ALONG WITH SOME DEVELOPING CU THROUGH THIS AFTERNOON. LIGHT SPRINKLES HAVE BEEN REPORTED AT LRD. LIGHT TO MODERATE NORTH TO NORTHEAST WINDS WILL PREVAIL TODAY INTO FRIDAY. EXPECT VFR CONDITIONS ACROSS THE REGIONAL AIRPORTS THE NEXT 24 HOURS. && .MARINE...AT 8 AM BUOY020 REPORTED A NORTH NORTHEAST WIND AROUND 10 KNOTS AND SEAS AT 3 FEET WITH A PERIOD OF 6 SECONDS. THE LOWER TEXAS COASTAL WATERS CONTINUE TO BE BETWEEN TWO WEATHER FEATURES. A SURFACE HIGH PRESSURE RIDGE EXTENDS FROM NORTHEASTERN TEXAS SOUTH AND WESTWARD INTO PORTIONS OF NORTHERN MEXICO THIS MORNING. MEANWHILE...A WEAK AREA OF LOW PRESSURE CONTINUES TO HOLD ACROSS THE BAY OF CAMPECHE REGION. NO DEVELOPMENT WITH THIS SYSTEM IS ANTICIPATED AS CONDITIONS ARE UNFAVORABLE AT THIS TIME. WOULD EXPECT MORE CLOUDS TO DEVELOP DURING THE DAY TODAY. AN ISOLATED SHOWER OR THUNDERSTORM OVER THE OFFSHORE WATERS IS POSSIBLE THIS AFTERNOON WITH SLIGHTLY BETTER CHANCES RETURNING ON FRIDAY. WINDS WILL REMAIN LIGHT TO MODERATE FROM THE NORTH TO NORTHEAST TODAY INTO FRIDAY. SEAS WILL CONTINUE TO BE RELATIVELY LOW THE NEXT 24 HOURS. && .PREV DISCUSSION...ISSUED 311 AM CDT THU SEP 18 2008...500 MB TROFFING OVER THE SOUTH CENTRAL PLAINS IS RESULTING IN SOME SCT CONV OVER CENTRAL TX EARLY THIS MORNING. MEANWHILE...OVER THE WESTERN GULF...THE OLD FRONTAL BOUNDARY IS FIRING OFF SOME ISOLD TO SCT CONV EXTENDING FROM NORTH TO SOUTH INTO THE BAY OF CAMPECHE. SHORT RANGE GUIDANCE MAINTAINS THE 500 MB TROFFING OVER TX AND DIGS IT STEADILY EAST TOWARDS THE SOUTHEASTERN U.S. THIS WEEKEND. THIS RESULTS IN PERSISTENT WEAK TO MODERATE SURFACE TROFFING OVER THE WESTERN GULF WHICH WILL KEEP UP THE THREAT OF SOME ISOLD TO SCT MARINE CONV JUST OFFSHORE OVER THE NEXT SEVERAL DAYS. THE BIG QUESTION IS HOW MUCH OF THE DEEPER MOISTURE LEVELS OFFSHORE WILL ADVECT IN OVER THE BRO CWA. BOTH THE GFS AND NAM KEEP THE BULK OF THE DEEPER MOISTURE POSITIONED JUST OFFSHORE IN THE SHORT RANGE. THE ECMWF SUPPORTS THIS GENERAL TREND AND WILL LEAVE OUT ANY SIGNIFICANT POPS IN THE SHORT RANGE. MAV AND MET TEMPS ARE IN PRETTY GOOD AGREEMENT REFLECTING SLOWLY WARMING TEMPS OVER THE NEXT SEVERAL DAYS. WILL LEAN TOWARDS THE SLIGHTLY WARMER MAV TEMPS. IN THE LONGER RANGE PERIOD...THE ECMWF AND THE GFS DIVERGE QUITE A BIT WITH THE GFS MAINTAINING A DRY BIAS WITH THE ECMWF MAINTAINING A WET BIAS. BOTH MODELS TRY TO BUILD SOME WEAK TO MODERATE 500 MB RIDGING OVER THE TX COAST WHICH EXPLAINS THE DRYNESS IN THE GFS. HOWEVER...THE ECMWF MAINTAINS A WEAKNESS IN THE 500 MB RIDGE OVER THE REGION WHICH MAY EXPLAIN THE HIGHER POPS AND BETTER MOISTURE FIELDS SHOWN IN THIS MODEL. THE ECMWF APPEARS TO BE COMING MORE IN LINE WITH THE GFS COMPARED TO YESTERDAYS RUNS AND WILL GO WITH A COMPROMISE OF POPS BETWEEN THE TWO WITH A MENTION OF A SLGT CHC POPS IN THE EXTENDED RANGE. MEX TEMP GUIDANCE SHOWS GOOD RUN TO RUN CONSISTENCY THROUGH DAY 7 WITH SO- SO CONSISTENCY SHOWING UP FOR POPS. ACCORDINGLY...WILL STICK PRETTY CLOSE TO THE MEX GUIDANCE FOR TEMPS. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 85 68 88 72 / 10 10 10 10 BROWNSVILLE 85 67 89 69 / 10 10 10 10 HARLINGEN 85 65 89 69 / 10 10 10 10 MCALLEN 86 65 90 67 / 10 10 10 10 RIO GRANDE CITY 87 65 91 68 / 10 10 10 10 SOUTH PADRE ISLAND 84 73 86 74 / 10 10 10 10 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT: HTTP://WWW.WEATHER.GOV/BROWNSVILLE 59/57 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 436 AM CDT FRI SEP 19 2008 500MB RUC ANALYSIS AND WATER VAPOR IMAGERY SHOW NEARLY ZONAL FLOW ACROSS TNE NORTHERN US AND A STRONG RIDGE ACROSS THE SOUTHERN CONUS. WITHIN THE RIDGE...A MID LEVEL LOW HAS DEVELOPED OVER THE CENTRAL PLAINS. THIS LOW IS EXPECTED TO REMAIN WEAK AS IT TRACKS ACROSS THE OHIO RIVER VALLEY THROUGH THE WEEKEND. MEANWHILE...AN ELONGATED TROUGH STRETCHING FROM HUDSON BAY DOWN THROUGH MN WILL TRACK ACROSS WI AND MI TODAY AND SATURDAY. THERE IS A STRONG TEMPERATURE GRADIENT AT 850MB ORIENTED WEST TO EAST THAT WILL DIP SOUTHWARD ACROSS LAKE MICHIGAN AND INTO OUR CWA BY SATURDAY NIGHT. .SHORT TERM...TODAY THROUGH SATURDAY... HIGH...THIN CLOUDS ASSOCIATED WITH THE MID LEVEL SYSTEM SHOULD LINGER TODAY...BUT SKIES WILL REMAIN SUNNY TO MOSTLY SUNNY. WITH SOUTHWEST WINDS AND MOSTLY SUNNY SKIES...TEMPERATURES WILL BE ALLOWED TO CREEP UP INTO THE UPPER 70S TO AROUND 80. BEHIND THE COLD FRONT SATURDAY NIGHT...850 MB TEMPS ARE PROGGED TO BE AROUND 10 TO 12C...CAUSING A CHILLY SUNDAY MORNING AND MILD SUNDAY AFTERNOON. PCPN CHANCES WITH THIS FRONTAL PASSAGE ARE SLIGHT...AS DEW POINT TEMPERATURES ARE EXPECTED TO REMAIN AT OR BELOW 60 ACROSS THE CWA THROUGH THE WEEKEND AND UPPER LEVEL FORCING IS NOT VERY STRONG. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY... DECIDED TO EXTEND THE SLIGHT CHANCE OF PCPN INTO SATURDAY EVENING (AS SHOWERS...NOT TSTORMS). NAM AND GFS SHOW ELEVATED CAPE VALUES IN THE 700-800 J/KG RANGE ABOVE AN INVERSION...ALTHOUGH THIS CAPE IS POSSIBLY OVERDONE DUE TO THEIR HIGHER DEWPOINTS PROGGED. HOWEVER...LOW-LEVEL FRONTOGENETICAL FORCING IS ENHANCED OVER SOUTH CENTRAL WI THROUGH 06Z...SO THERE IS STILL A CHANCE OF A LINGERING SHOWER FOR A COUPLE OF HOURS BEYOND SUNSET. AFTER THE TROUGH PASSES...HIGH PRESSURE WILL AGAIN MAKE ITS WAY INTO THE REGION. SOUTHERLY WINDS WILL PERSIST THROUGH THE WEEK. A LOW PRESSURE TROUGH IS EXPECTED TO INTENSIFY OVER THE NORTHERN PLAINS ON WEDNESDAY. THERE IS ENOUGH AGREEMENT IN THE MODELS TO BRING THE SLIGHT CHANCE OF SHOWERS AND TSTORMS FURTHER EASTWARD ON WEDNESDAY...SO DID SO IN COORDINATION WITH GRB. && .AVIATION...INFLUENCE OF HIGH PRESSURE EXPECTED TO KEEP VFR CONDITIONS WITH SCT-BKN THIN CI THROUGH THIS FORECAST PERIOD. FORECAST 15-20KT 925 MB WINDS INDICATE ENOUGH MIXING TONIGHT TO PREVENT MENTION OF FOG IN TAFS...BUT ONCE AGAIN SOME PATCHY MIFG POSSIBLE. .MARINE...POTENTIAL IS THERE FOR A SMALL CRAFT ADVISORY...ESPECIALLY IN NRN ZONES. WAVE MODEL PRODUCING 3 TO 4 FOOT WAVES BEFORE LOWERING WITH EXPECTED SHIFT TO SWLY DIRECTION LATE THIS AFTERNOON/EVENING. IF SOUTH WINDS BECOME STRONGER THAN EXPECTED...OR OFFSHORE SHIFT OCCURS LATER THAN FORECAST SCA MAY BE NEEDED. BETTER CHANCE FOR AN SCA COMES SATURDAY NIGHT INTO SUNDAY MORNING WITH INCREASING NE WINDS AND FAVORABLE FETCH BEHIND FRONT. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ SHORT/LONG TERM...13/MRC AVIATION/MARINE...09/REM wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 244 AM MDT SAT SEP 20 2008 .DISCUSSION... 244 AM MDT SAT SEP 20 2008 FORECAST PROBLEMS WILL BE CHANCES OF PRECIPITATION INTO THE BEGINNING OF NEXT WEEK...WINDS SUNDAY AND MONDAY...AND MAX TEMPERATURES... ESPECIALLY ON SUNDAY. SATELLITE SHOWING A PROGRESSIVE FLOW FROM THE CENTRAL PACIFIC INTO NORTH AMERICA. NUMEROUS SHORTWAVE TROUGHS IN THIS FLOW OVER THE PACIFIC. MAIN SYSTEM INTEREST IS JUST PUSHING ONTO THE WEST COAST. AT JET LEVEL MODELS INITIALIZED REASONABLY. AT MID LEVELS...BASED ON SATELLITE INITIALLY THE RUC/ECMWF FOLLOWED BY THE GFS WERE DOING THE BEST ON THE POSITION. BY 06Z...ALL THE MODELS EXCEPT THE UKMET AND NGM HAD THE BEST HANDLE ON IT. UPPER AIR ANALYSIS SHOWED THAT THE UKMET WAS DOING SLIGHTLY BETTER THAN THE ECMWF/GFS WITH THE SYSTEM. ON THE RIDGE AHEAD OF THIS SYSTEM...THE MODELS TENDED TO NOT BE STRONG ENOUGH/TOO FAR EAST. HEAR THE GFS WAS DOING SLIGHTLY BETTER THAN THE UKMET AND ECMWF. THE GFS ALSO LOOKS TO HAVE A LITTLE BETTER HANDLE ON THE MID LEVEL MOISTURE. AT THE SURFACE...THE NAM/UKMET/ECMWF WERE DOING THE BEST THROUGH THE PERIOD WITH THE GFS THE OUTLIER. MODELS INITIALIZED WELL ON TEMPERATURES BUT WERE A TAD WARM ON TOP OF US TO START WITH. MODELS ARE NOT TOO DIFFERENT. WILL TEND TO WITH BLEND OF THE NAM...UKMET... AND ECMWF FOR THIS FORECAST. TODAY/TONIGHT...WILL START OUT WITH LIGHT AND VARIABLE WINDS TO START WITH AS A SURFACE TROUGH AS A RESULT OF A NORTHERN STREAM WAVE STALLS AND THEN EVENTUALLY WASHES. LEE TROUGH STARTS DEVELOPING IN THE AFTERNOON AND CONTINUES TO STRENGTHEN THROUGH THE NIGHT. NOT THE GREATEST WIND SET UP TO GET VERY WARM TEMPERATURES. WILL TEND TO GO NEAR TO SLIGHTLY BELOW THE WARMER GUIDANCE. NOW THE FORECAST STARTS GETTING INTERESTING. MODELS INDICATING INSTABILITY/CAPE ALOFT. LOW LEVEL JET GETS GOING AS WELL. THETA-E LAPSE RATES AND MID LEVEL FRONTOGENESIS LINE UP BEST OVER THE NORTHERN AND EASTERN PORTIONS OF THE AREA. MODELS SHOW QPF IS THIS AREA AS WELL. ONE DIFFERENCE IS IN THE TIMING. THE NAM IS FASTER/FURTHER NORTH AND EAST WITH BREAKING OUT THE PRECIPITATION. NAM LOOKS MORE REASONABLE AT THIS TIME WITH ITS PLACEMENT. SUNDAY/SUNDAY NIGHT...ELEVATED CONVECTION SHOULD BE ONGOING IN THE EAST IN THE MORNING. GETS A LITTLE TRICKIER IN THE AFTERNOON. DEPENDING ON HOW STRONG AND EXTENSIVE THE OVERNIGHT AND EARLY MORNING CONVECTION IS COULD AFFECT HOW FAST CONVECTION DEVELOPS IN THE AFTERNOON...IF AT ALL. MODELS HINT AT AN AREA OF NO PRECIPITATION WITH ONGOING OR CONTINUING THUNDERSTORMS IN THE EAST AND NORTHEAST. MODELS TRY TO RELOAD AND FIRE OFF NEW CONVECTION IN THE WEST WITH NEW LOW LEVEL CONVERGENCE AND MID LEVEL LIFT. HOWEVER...MODELS SHOW CAP STILL NOT QUITE BROKEN. WAS CREATIVE WITH THE LAYOUT OF PRECIPITATION BUT HAD A HARD TIME PUTTING IT IN FOR EVERYONE. GRADIENT REALLY TIGHTENS UP SUNDAY...ESPECIALLY OVER THE KANSAS AND NEBRASKA OF THE AREA. INDICATIONS ARE THAT WINDY CONDITIONS WILL DEVELOP HERE AND COULD DEVELOP GUSTS TO NEAR ADVISORY CRITERIA. WILL HAVE A LIMITED AMOUNT OF SUN WHICH MAY HOLD SPEEDS BACK A LITTLE. DUE TO CLOUD COVER AND UNFAVORABLE DIRECTION OF WINDS WILL TEND TO BE NEAR TO SLIGHTLY BELOW GUIDANCE WITH THE NORTHEAST SECTION THE COOLEST. DEEPEST MOISTURE...INSTABILITY...AND LIFT COINCIDE VERY WELL OVER THE EASTERN HALF TO TWO-THIRDS OF THE FORECAST AREA DURING THE NIGHT. SO WEIGHTED THE HIGHER POPS IN THAT AREA. MONDAY/MONDAY NIGHT...AGAIN WILL BE DEPENDENT ON HOW MUCH EARLY MORNING CONVECTION THERE IS. LOOK TO BE SOME LINGERING PRECIPITATION IN THE EAST EARLY. THEN NEXT MID BATCH OF MID LEVEL LIFT AND MOISTURE MOVE INTO THE WEST IN THE AFTERNOON. GFS SHOWS THE AIR MASS CAPPED IN MOST AREAS IN THE AFTERNOON WHEREAS THE NAM IS SHOWING THE WEST WITH NO CINH. HOWEVER...MODELS ARE DIFFERENT IN SURFACE LOW POSITION. HOWEVER...THEY DO SHOW THE LEAST AMOUNT OF LOW LEVEL MOISTURE OVER THE SOUTHWEST PORTION AND THE BEST OVER THE NORTHERN AND EASTERN LOCATIONS. AM IMPRESSED WITH THE LIFT THAT MOVES ACROSS FROM LATE AFTERNOON INTO THE NIGHT BUT AM NOT SURE OF MOISTURE AVAILABILITY. MODELS ALSO DISAGREE ON POSITION/SPEED OF FRONT MOVING THROUGH. AT THIS TIME WILL INTRODUCE SLIGHT CHANCE IN THE AFTERNOON IN THE WEST AND ACROSS THE ENTIRE AREA THAT NIGHT. PRECIPITATION LOOKS TO BE DONE BY 12Z. MODELS REALLY WARM UP TEMPERATURES...ESPECIALLY IN THE SOUTHWEST. THIS MAKES SENSE IF THE DRY AIR ENDS UP THERE. WILL TEND TO NEAR TO SLIGHTLY BELOW GUIDANCE. TUESDAY/TUESDAY NIGHT...WOULD NOT NORMALLY GO THIS FAR ON THE MID SHIFT. BUT ANOTHER PRECIPITATION SHOT IS IN THE GRIDS FOR THE LATE AFTERNOON AND OVERNIGHT. DESPITE THE FACT COULD HAVE SOME LINGERING IN THE EAST VERY EARLY TUESDAY MORNING...AREA LOOKS TO BE UNDER SUBSIDENCE AND TEMPORARY DRYING AT MID LEVELS. ALSO WILL BE UNDER THE INFLUENCE OF THE SURFACE MOST OF THE DAY. WILL REMOVE THE PRECIPITATION FROM TUESDAY. AM NOT SOLD ON THE SLIGHT CHANCE FOR THE NIGHT. HOWEVER...SOME INCREASE IN MOISTURE AND INSTABILITY ALONG WITH A SHORTWAVE TROUGH LATER IN THE NIGHT. WILL KEEP THE PRECIPITATION IN FOR THE WHOLE PERIOD BUT EXPECT IT TO BE BETWEEN 06Z AND 12Z. COOL TEMPERATURES WILL ALSO BE IN PLACE FOR TUESDAY AS WELL. THANKS TO ALL FOR COLLABORATION. BULLER && .AVIATION... 1100 PM MDT FRI SEP 19 2008 FOR 06Z TAFS...VFR CONDITIONS EXPECTED THROUGH AT LEAST THE NEXT 24 HOURS. FEW250 WITH LIGHT/VAR WINDS UNDER 6KT WILL PERSIST THROUGH 16Z-18Z BEFORE INCREASING FROM THE SOUTHEAST AT 10-13KTS. CUMULUS CLOUDS WITH BASES OF 6-9K FT WILL ALSO DEVELOP DURING THE AFTERNOON WITH MID AND HIGH LEVEL CLOUDINESS INCREASING BY EARLY EVENING AHEAD OF AN APPROACHING UPPER LEVEL TROUGH. DDT && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 339 AM EDT SAT SEP 20 2008 .SYNOPSIS.../ISSUED AT 337 AM/ A COLD FRONT WILL PUSH SOUTH ACROSS NORTHERN MICHIGAN TODAY...PRODUCING SCATTERED RAIN SHOWERS AND MAYBE SOME THUNDER. IN ITS WAKE...COOL CANADIAN HIGH PRESSURE WILL BUILD ACROSS THE REGION INTO THE FIRST HALF OF THE NEXT WORK WEEK. MPC && .SHORT TERM.../ISSUED AT 337 AM/...TODAY 02Z SURFACE/RUC ANALYSIS AND IR/WV/RADAR IMAGERY SHOW A COLD FRONT DROPPING SOUTHEAST ACROSS ONTARIO/LAKE SUPERIOR AND CENTRAL MN...AND A SURFACE TROUGH EMANATING FROM THE FRONT ACROSS SOUTHERN MN AND SOUTHEAST SD. DESPITE MID/UPPER LEVEL FORCING FAR TO THE NORTH ACROSS ONTARIO...BAND OF ENHANCED MOISTURE IS INTERACTING WITH STEEP MID-LEVEL LAPSE RATES BETWEEN 7-7.5 C/KM TO PRODUCE SCT SHOWERS AND ISOLD THUNDERSTORMS ACROSS EASTERN UPPER/NORTHERN LAKE MICHIGAN AND WISCONSIN. ADDITIONAL CONVECTION ALSO IS OCCASIONALLY POPPING UP OVER LAKE SUPERIOR RIGHT AHEAD OF THE FRONT WHERE ELEVATED INSTABILITY DEPICTED BY THE RUC IS ESTIMATED AT 200-600 J/KG. AS THIS FRONT CONTINUES TO PROGRESS SE TODAY...THE MAIN FORECAST CONCERNS INCLUDE THUNDERSTORM CHANCES OVER THE NEXT 24 HOURS. TODAY...MID-LEVEL MOISTURE AXIS WILL THIN AS IT CONTINUES TO SHIFT SOUTH THIS MORNING. MID-LEVEL LAPSE RATES WILL ALSO REMAIN STEEP WITHIN THIS BAND...SO FIND IT HARD TO RULE OUT ELEVATED SPOTTY SHOWERS AND A RUMBLE OF THUNDER AS IT REACHES THE SOUTHERN FORECAST AREA BY EARLY AFTERNOON. MEANWHILE...COLD FRONT OVER LAKE SUPERIOR WILL ALSO BE DROPPING SOUTH...CLEARING EASTERN UPPER BY EARLY AFTERNOON...AND THE SE FORECAST AREA BY EARLY IN THE EVENING. MODEL SOUNDINGS INDICATE CONVECTION SHOULD BE CAPPED OFF FROM THE SURFACE PRIOR TO 18Z...BUT SUBTLE COOLING AROUND 800MB SUGGESTS THIS CAP ERODES SHORTLY THEREAFTER. UPSTREAM OBS SHOW MOISTURE POOLING ALONG THE FRONT WILL YIELD UPPER 50 SURFACE DEWPOINTS...WHICH WOULD TRANSLATE TO ML CAPES CLOSE TO 800 J/KG ACROSS THE SOUTHEAST FORECAST AREA. BEST WIND FIELDS RESIDE BEHIND THE FRONT SO ORGANIZED CONVECTION IS NOT EXPECTED. BUT FAVORABLE THERMODYNAMIC PROFILE WITH THE STEEP MID-LEVEL LAPSE RATES FAVOR A CHANCE FOR SMALL HAIL. WILL MENTION HAIL UP TO 1/2 INCH IN THE HWO FOR AREAS EAST OF I 75 AND SOUTH OF M-32 FOR THE AFTERNOON. MPC && .LONG TERM.../ISSUED AT 337 AM/...TONIGHT AND BEYOND TONIGHT...COLD FRONT SETTLES SOUTH OF THE AREA DURING THE EVENING AND 1028MB HIGH PRESSURE NOSES IN. NORTH TO NORTHEAST LOW LEVEL WINDS WILL COLD ADVECT 850MB TEMPS IN THE 2C TO 3C RANGE ACROSS THE NORTHEAST FORECAST AREA BY EARLY IN THE MORNING...BUT ALSO VERY DRY AIR TO THE TUNE OF 15 PCT RH BETWEEN 850-700MB. SO EVEN THOUGH INSTABILITY WILL BE BUILDING ACROSS LAKE HURON...THIS DRY AIR MAY MITIGATE STRATO-CU DEVELOPMENT OVER THE NE FORECAST AREA SOMEWHAT. BUT BECAUSE OF THE INCOMING COLD AIR...INLAND AREAS ACROSS EASTERN UPPER MAY APPROACH THE FREEZING MARK AND HAVE ADDED PATCHY FROST TO THE FORECAST. SUNDAY AND SUNDAY NIGHT...SURFACE HIGH PRESSURE SHIFTS NORTH OF THE FORECAST AREA. THERMAL TROUGH WILL PASS TO THE EAST DURING THE MORNING AND 850MB TEMPS MODERATE SOMEWHAT DURING THE AFTERNOON. WOULDNT BE SURPRISED TO SEE A SCT/BKN CU FIELD DEVELOP BY LATE MORNING ACROSS THE NE CWA...BUT WARMING LOW LEVEL TEMPS AND DECREASING MOISTURE FLUX OFF LAKE HURON WILL HELP CU ERODE DURING THE AFTERNOON. MID-LEVEL WARM ADVECTION CLOUDS THEN SPREAD ACROSS THE AREA DURING THE EVENING AND OVERNIGHT. THESE CLOUDS DESPITE LIGHT WINDS SHOULD PREVENT ANY FROST CONCERNS FROM OCCURING. MONDAY THROUGH WEDNESDAY...SHORTWAVE RIDGING AND SURFACE HIGH PRESSURE WILL ENSURE TRANQUIL CONDITIONS ACROSS THE NORTHWOODS MONDAY AND TUESDAY WITH WARMING TEMPERATURES OVER THE PERIOD. BY WEDNESDAY...POTENT SHORTWAVE ROUNDING THE BASE OF AN UPPER LOW OVER NORTH-CENTRAL WISCONSIN WILL PUSH A COLD FRONT TOWARDS THE AREA. STILL SOME TIMING CONCERNS HERE...BUT WILL ADJUST FORECAST TO LINE UP WITH THE SURROUNDING OFFICES. MPC && .MARINE.../ISSUED AT 337 AM/ WAVE HEIGHTS OVER NORTHERN LAKE MICHIGAN HAVE DECREASED SUBSTANTIALLY FROM EIGHT FEET LAST EVENING BUT WILL TAKE A LITTLE LONGER TO SUBSIDE GIVEN WIND SPEEDS STILL GUSTING TO 20 KNOTS. THESE WINDS WILL DIMINISH THROUGH THE MORNING SO WILL ONLY EXTEND SMALL CRAFT ADVISORIES UNTIL LATE MORNING. THEREAFTER...NO FURTHER HEADLINES ARE EXPECTED SINCE WINDS AND WAVES WILL REMAIN BELOW CRITERIA WITH HIGH PRESSURE AND A WEAKER PRESSURE GRADIENT OVER THE AREA. MPC && .AVIATION.../ISSUED AT 1127 PM/...VALID FOR 06Z TAFS AHEAD OF APPROACHING COLD FRONT - NOW MOVING THROUGH WESTERN LAKE SUPERIOR - VFR CONDITIONS WILL PREVAIL THROUGH SATURDAY AM. HOWEVER...STRONG WINDS JUST OFF THE SFC WILL LEAD TO THE RISK OF LOW LEVEL WIND SHEAR THROUGH THE OVERNIGHT HOURS. ON SATURDAY...COLD FRONT EXPECTED TO SLIP THROUGH THE REGION PASSING THROUGH THE TERMINAL SITES BY 18Z. WILL BE A LOW END CHANCE FOR SHOWERS/THUNDER AT TVC/PLN WITH THE FRONT. BUT BETTER CHANCES WILL BE FOUND AT APN AFTER 18Z...WHERE SOME DAYTIME HEATING AHEAD OF THE FRONT WILL HELP DESTABILIZE THINGS JUST A BIT. THEN...WITH COOLER AIR SLIPPING IN BEHIND THE FRONT...ANTICIPATED A FEW HOUR PERIOD OF MVFR CIGS SATURDAY AFTERNOON...WITH MVFR CIGS PERSISTING AT APN INTO THE EVENING AS COOL FLOW TURNS NORTHEAST OFF LAKE HURON. ADAM && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR LMZ341-342-344>346. LH...SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR LHZ345. LS...SMALL CRAFT ADVISORY UNTIL 5 AM EDT EARLY THIS MORNING FOR LSZ321. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 140 AM EDT SAT SEP 20 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAF ISSUANCE .UPDATE... A THIN LINE OF SHRA/TSRA HAVE DVLPD ALG COLD FNT OVER THE MN ARROWHEAD...SO ADDED LO CHC POPS TO THE WRN CWA THRU 06Z...WHEN THIS FNT IS EXPECTED TO PASS. ALTHOUGH LOSS OF SFC HTG MAY CAUSE THIS CNVCTN TO WEAKEN...STEEP LAPSE RATES UP TO 7.5C/KM IN THE H7-5 LYR SHOULD ALLOW THE SHRA TO LINGER IN THE PRESENCE OF SOME H85-5 QVECTOR CNVGC AND LLVL CNVGC ASSOCIATED WITH THE COLD FNT. && .SYNOPSIS... 19Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING OVER THE WESTERN U.S. AND TROUGHING DROPPING DOWN THROUGH CENTRAL CANADA. AHEAD OF THIS TROUGH...A SHRTWV STRETCHES FROM NE ONTARIO SW TO NW WI...WHICH IS COMBINING WITH MID-LEVEL FRONTOGENESIS AND 7-7.5C/KM LAPSE RATES IN PRODUCING ISOLATED SHOWERS AND THUNDERSTORMS ON LAKE SUPERIOR INTO THE KEWEENAW. AHEAD OF THE TROUGH...WARM AIR HAS MOVED INTO UPPER MI FROM THE PLAINS...WITH A 15Z SOUNDING FROM SAW SHOWING 850MB TEMPS OF 16C. TEMPERATURES HAVE NOT MIXED UP TO THIS LEVEL...DESPITE A BREEZY SOUTHWEST WIND...DUE TO THE LOWER SUN ANGLE AROUND THE AUTUMNAL EQUINOX. NEVERTHELESS... READINGS HAVE CLIMBED ABOVE NORMAL WITH DOWNSLOPE AREAS AROUND 80...WHILE LOCATIONS DOWNWIND OF THE COOLER LAKE MI WATERS ARE IN THE MID 60S. TO THE NW...COOLER AIR CAN BE SINKING SOUTHWARD THROUGH MANITOBA...BEHIND A STRONG COLD FRONT. TEMPERATURES ARE FALLING INTO THE 40S OVER CENTRAL MANITOBA...COMPARED TO 70 DEGREE READINGS AHEAD OF THE FRONT. 850MB TEMPS WERE 1C AT CYQD AT -4C AT CHURCHILL MB...INDICATIVE ALSO OF THE COLD AIR. SOME CELLULAR LOW CLOUDS ARE ASSOCIATED WITH THE COLD AIR...BUT VERY FEW REPORTS OF ANY PCPN. FARTHER TO THE NW...HIGH PRESSURE IS LOCATED OVER FAR NORTHERN SASKATCHEWAN. && .SHORT TERM (TONIGHT AND SATURDAY)... UPPER LEVEL TROUGH OVER CENTRAL CANADA WILL DIG A BIT MORE TOWARDS UPPER MI DURING THE NEXT 18 HOURS...BUT THEN START MOVING EASTWARD DUE TO UPPER TROUGH JUST OFF THE WEST COAST TRYING TO PUSH EAST. THE DIGGING WILL BE ENOUGH TO DRIVE THE COLD FRONT SOUTH ACROSS THE CWA...THOUGH...CROSSING UPPER MI TONIGHT AND REACHING THE MILWAUKEE AREA BY 00Z SUN. UNTIL THE COLD FRONT ARRIVES (OR THE TROUGH DIGS ENOUGH SOUTH)...THE AREA WILL BE UNDER WEAK MID-LEVEL FRONTOGENESIS AND 7-7.5C/KM LAPSE RATES. THE GFS AND NAM SHOW LIGHT QPF GRADUALLY SINKING SE WITH TIME...WHICH SEEMS REASONABLE GIVEN THE FRONTOGENESIS. ADJUSTED THE FORECAST TO CONTINUE 20 POPS THROUGH MUCH OF THE NIGHT...PARTICULARLY IN THE CENTRAL U.P. SINCE THE UPPER FLOW DOES NOT APPEAR TO ALLOW FOR A FAST MOTION SOUTH WITH THE PCPN. AFTER THE FRONT PASSES...LOW CLOUDS SEEN OVER MANITOBA WILL MOVE INTO UPPER MICHIGAN...WITH THE GREATEST COVERAGE OVER THE NORTH CENTRAL U.P. WHERE UPSLOPE AND LAKE ENHANCEMENT IS EXPECTED. CLOUDS ARE EXPECTED TO STICK AROUND THROUGH MUCH OF THE MORNING UNTIL DRIER AIR AND ANTICYCLONIC LOW LEVEL FLOW ASSOCIATED WITH THE HIGH OVER NRN SASKATCHEWAN NOSING IN...ALONG WITH DAYTIME MIXING...HELP MIX/CLEAR THEM OUT SATURDAY AFTERNOON. DECLINED TO MENTION ANY PCPN WITH THE LOW CLOUDS GIVEN LACK OF REPORTS UPSTREAM AND THAT SOUNDINGS SUGGEST THE MOISTURE TO BE QUITE SHALLOW. BIGGEST IMPACTS FROM THE COLD FRONT MOVING ACROSS WILL BE ON TEMPS AND WINDS. LOW TEMPS TONIGHT ARE LIKELY OCCURRING TOWARD SUNRISE SINCE THEY PROBABLY WILL NOT FALL OFF MUCH UNTIL THE FRONT PASSES...DUE TO A SW BREEZE KEEPING THE BOUNDARY LAYER MIXED. GUSTY NORTH WINDS BEHIND THE FRONT SHOULD BRING TEMPS DOWN INTO THE 50S AND POSSIBLY UPPER 40S...COOLEST OVER THE HIGHER TERRAIN OF THE WEST HALF OF UPPER MI. WITH THE COOL AIR MOVING IN LATE TONIGHT...TEMPS ARE GOING TO STRUGGLE RISING TOMORROW. LATEST MET/MAV GUIDANCE ARE A FEW DEGREES COOLER THAN THE PREVIOUS FORECAST...AND GIVEN WHAT TEMPERATURES ARE DOING UPSTREAM OVER NORTHERN MANITOBA...FEEL THAT IS PROBABLY THE WAY TO GO. MUCH OF THE NORTHERN U.P. SHOULD BE STUCK IN THE 50S...THANKS TO 900MB TEMPS DROPPING TO 2-4C. THE SOUTHERN U.P. WILL BE WARMER...ESPECIALLY DOWN NEAR MNM WHERE 900MB TEMPS ARE THE WARMEST. .LONG TERM (SAT NIGHT THROUGH NEXT FRI)... FIRST ISSUE IN THE LONG TERM IS POTENTIAL FOR FREEZING TEMPS AND WIDESPREAD FROST AWAY FM THE IMMEDIATE LAKE SUPERIOR SHORE. LARGE HIGH PRESSURE SETTLES IN BEHIND THE COLD FRONT THAT MOVES THROUGH EARLY SATURDAY. INITIALLY DURING SATURDAY EVENING...NORTHERLY BLYR WINDS KEEP TEMPS FM FALLING TOO QUICKLY BUT EVENTUALLY WINDS MOST EVERYWHERE WILL BECOME LIGHT. LIGHT WINDS AND SKIES BECOMING CLEAR SET UP A GOOD RADIATIONAL COOLING NIGHT...ESPECIALLY AS VERY DRY AIR MOVES ACROSS IN THE FORM OF A PRECIPITABLE WATER MINIMUM. COOP GUIDANCE CONTINUES TO INDICATE MINS IN FAVORED COLD SPOTS FALLING BLO 32F AND HAVE WENT THIS WAY WITH THE LATEST MIN TEMP GRIDS. INCREASED FROST COVERAGE AS WELL...WITH WIDESPREAD FROST EXPECTED OVR MUCH OF THE CWA...AWAY FM THE LAKE SUPERIOR SHORE. THOUGHT ABOUT GOING WITH MINS BLO GUIDANCE ALONG LK MICHIGAN SHORE TOO AS KESC CAN FALL OFF MORE THAN GUIDANCE SHOWS IN THESE TYPE OF SETUPS...BUT SINCE EAST WINDS FLOWING OFF LK MICHIGAN LATE MAY PROMOTE SOME LAKE EFFECT CLOUDS (DELTA T/S APPROACH 10C WITH LK MI WATER TEMPS NEAR 17C) KEPT SHORELINE IN THE UPR 30S-LWR 40S. ONLY HEADLINE POSTED ATTM WAS A FREEZE WATCH FOR INTERIOR WEST CWA...SOUTHERN HOUGHTON TO BARAGA AND ALSO IRON. FROST ADVY LIKELY WILL BE NEEDED FOR MUCH OF THE CWA BUT WILL LEAVE THAT TO LATER SHIFTS AS IT IS STILL IN THE LONG TERM. NEXT ISSUE IS THE PERSISTENT QPF GFS SHOWS ALONG TIGHTENING H85 FRONT FOR SUN/SUN NIGHT. SIMILAR TO PAST MODEL RUNS...GFS REMAINS LARGELY ON ITS OWN AND WILL CONTINUE TO DISCOUNT. APPEARS THAT QPF IS TIED TO STEEPENING H85-H7/H7-H5 LAPSE RATES AOA 7.0C/KM AS A RESULT OF WARM ADVECTION AT H7. THERE IS ALSO SOME WEAK MID LEVEL FGEN PRESENT ALONG H85 FRONT AS WELL. WARM FRONT...FIRST AT H85 THEN AT THE SFC...LIFT THROUGH CWA SUNDAY NIGHT. AS IT LOOKED YDY...BEST H85 MOISTURE TRANSPORT AND ALSO THE STEEPER POCKET OF LAPSE RATES TEAM UP TO THE NW OF UPR LAKES INTO MANITOBA AND ONTARIO. SOUNDINGS SHOW A MID CLOUD DECK STREAMING ACROSS THE CWA LATE SUN INTO SUN NIGHT. DRY LOW LEVELS BLO THIS CLOUD BASE SHOULD PROHIBIT MUCH IN THE WAY OF PCPN AND THUS KEPT THE FORECAST DRY OVER CWA. THE COOLER TEMPERATURES AND UPPER LEVEL TROUGH FM THIS WEEKEND IS THEN REPLACED BY A WARMING TREND EARLY THIS WEEK AS UPPER RIDGE OVER THE SOUTHWEST CONUS BUILDS INTO GREAT LAKES PUSHING THE WARM FRONT NORTH OF THE REGION. WESTERN CONUS TROUGH UPSTREAM OF THE RIDGE SHIFTS EAST BY MIDWEEK BRINGING THE RETURN OF A COLD FRONT AND A CHANCE OF SHOWERS AND THUNDERSTORMS INTO THE WESTERN GREAT LAKES. EXTENDED MODELS USED...GFS/ECMWF/UKMET/CANADIAN GLOBAL...AND GFS ENSEMBLE AGREE IN THE LARGE SCALE PATTERN. TIMING OF THE COLD FRONT AND PCPN CHANCES INTO THE AREA REMAINS MAIN FOCUS OF THE EXTENDED. MAJORITY OF GUIDANCE...EXCEPT THE GFS ENSEMBLES...INDICATE A FROPA ON WED. SINCE THE GFS AND ECMWF NOW ARE IN AGREEMENT WITH THAT IDEA PLACED HIGHEST POPS IN THE GRIDS AT THAT TIME. INCREASING MOISTURE ADVECTION AT H85 AHEAD OF THE FRONT COULD EVEN TRIGGER SCATTERED SHOWERS OUT OF A MID CLOUD DECK AS EARLY AS TUESDAY. BUT SINCE GREATEST GRADIENT IN THIS ADVANCING MOISTURE STAYS OVR WESTERN LK SUPERIOR...KEPT ANY POPS TUE OUT OF THE LAND PORTION OF THE WESTERN CWA UNTIL LATE TUE NIGHT. THESE MID CLOUDS ON TUE COULD AFFECT MAX TEMPS. MIXING TO H85 TEMPS IN MID TEENS RESULTS IN MAX TEMPS INTO THE LWR 80S BUT DUE TO POSSIBLE CLOUDS...TEMPERED THIS BACK TO THE MID-UPR 70S WHICH IS STILL A NUDGE ABOVE MOST GUIDANCE. FRONT CLEARS MOST OF CWA BY LATER THU BUT THEN STALLS OUT JUST TO THE SOUTH OVR WI AND LWR MI AS THE BOUNDARY BECOMES PARALLEL TO THE UPPER FLOW. DOES NOT SEEM THAT BOUNDARY IS FAR ENOUGH AWAY TO DROP POPS IN ITS WAKE. IN FACT...LATEST GFS/ECMWF NOW INDICATE A H85-H7 WAVE RIDES ALONG THIS SFC BOUNDARY TO BRING A WIDESPREAD RAIN TO UPR LAKES THU. MOST PCPN WOULD BE OUT OF THE CWA ON FRIDAY...BUT THE APPROACH OF A MORE NORTHERN STREAM ORIGIN WAVE MAY BRING ANOTHER CHANCE FOR RAIN LATE IN THE DAY. JUST INCLUDED SOME POPS OVR WRN LK SUPERIOR AT THIS POINT. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... EXPECT A SHARP WSHFT TO NNE FOLLOWING COLD FROPA EARLY THIS MRNG. AIRMASS UPSTREAM BEHIND THE FNT IS NOT PARTICULARLY MOIST PER 00Z YPL/INL RAOBS AND SFC OBS...SO EXPECT A BKN SC DECK/MVFR CONDITIONS TO DVLP ONLY AT SAW WHERE EXPECTED POST FROPA WIND WL UPSLOPE AS MUCH COOLER AIR ARRIVES ON THE HEELS OF GUSTY WINDS. DIURNAL HTG WL SCT OUT THIS MVFR DECK AT SAW SAT AFTN...WITH VFR CONDITIONS DOMINATING LATE IN THE DAY WITH ARRIVAL OF CORE OF DRY AIRMASS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... SW WINDS OF 15 TO 30 KT...GREATEST OVER NORTH CENTRAL AND FAR EASTERN LAKE SUPERIOR...WILL DIMINISH BRIEFLY THIS EVENING...THEN RAPIDLY INCREASE OUT OF THE N OR NE TO 20 TO 30 KT AFTER MIDNIGHT IN THE WAKE OF A COLD FRONT DROPPING SOUTH ACROSS LAKE SUPERIOR. TOUGH CALL ON WHETHER OR NOT WINDS WILL REACH GALE FORCE ON NORTH CENTRAL AND EASTERN LAKE SUPERIOR LATE TONIGHT. RAPID PRESSURE RISES BEHIND THE FRONT WOULD SUGGEST IT...BUT WIND REPORTS AT EXPOSED LOCATIONS...EVEN ON LAKE WINNIPEG...HAVE BEEN GENERALLY 30 KT OR LESS. THEREFORE...HAVE NOT GONE WITH A GALE WARNING AND MENTIONED A FEW GALE FORCE GUSTS INSTEAD. WINDS WILL NEED TO BE MONITORED AND A GALE WARNING COULD STILL BE ISSUED. OTHERWISE...HIGH PRESSURE OVER NRN SASKATCHEWAN NOSING SE INTO LAKE SUPERIOR ON SAT WILL HELP DIMINISH THE WINDS TO UNDER 20 KT BY SAT EVENING. LIGHT WIND REGIME PERSISTS INTO MONDAY THEN SOUTH WINDS AHEAD OF THE APPROACHING COLD FRONT INCREASE TO 30 KNOTS TUE BEFORE DIMINISHING ON WED. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... FREEZE WATCH LATE SATURDAY NIGHT THROUGH EARLY SUNDAY MORNING MIZ004-010-084. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ UPDATE...KC SYNOPSIS/SHORT TERM..AJ LONG TERM...JLA AVIATION...KC MARINE...AJ/JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1259 AM CDT SAT SEP 20 2008 .UPDATE... HAVE TWEAKED THE OVERNIGHT GRIDS TO INCLUDE PATCHY FOG ACROSS MOST OF CENTRAL AND WEST CENTRAL MN. LIGHT WINDS...CLEAR SKIES...AND SATURATED SOIL FROM THE RAINFALL FRIDAY EVENING HAVE CONTRIBUTED TO PATCHY FOG AND ATTENDANT VISIBILITIES BETWEEN 1/2 MILE AND 2 MILES. EXPECT THE MOST WIDESPREAD FOG TO EXTEND ALONG AND NORTH OF A LINE FROM FROM MILACA TOWARD ST CLOUD...WILLMAR...AND CANBY. && .DISCUSSION.../ISSUED 833 PM CDT FRI SEP 19 2008/ UPDATE TO FORECAST WILL MAINLY BE TO UPDATE WORDING FOR THE OVERNIGHT PERIOD... WITH MINIMAL CHANGES TO THE GOING FORECAST. FRONTAL BOUNDARY CONTINUES TO SLOWLY SAG SOUTHEASTWARD... WITH CONVECTION DISSIPATING AS DAYTIME INSTABILITY FADES. SOME ELEVATED INSTABILITY WILL REMAIN ACROSS THE SOUTHERN PORTION OF THE AREA THROUGH THE OVERNIGHT HOURS... ALTHOUGH THERE APPEARS TO BE VERY LIMITED FORCING TO GET ANY ELEVATED ACTIVITY GOING. HOWEVER... WITH THE NAM... RUC... AND LOCAL LAPSWRF KEEPING SOME NEARLY SATURATED RH IN THE 850-700MB LAYER THROUGH 12Z IT WOULD BE TOUGH TO RULE OUT AN ISOLATED SHRA/TSRA. THE BETTER FORCING... OWING TO FRONTOGENESIS AND THE ACTUAL 1000-850MB BAROCLINIC ZONE... IS FARTHER NORTH NEAR WHERE THE STRONGER CONVECTION IN NORTHEAST MINNESOTA WAS EARLIER IN THE EVENING. THIS DOES DROP SOUTHEASTWARD OVERNIGHT... ALTHOUGH IT WEAKENS AND WITH THE BOUNDARY LAYER STABILIZING... DO NOT BELIEVE IT WILL BE ABLE TO KICK OFF ANY FURTHER ACTIVITY. KMPX 00Z RAOB SUGGESTED BEST POTENTIAL FOR ANY ELEVATED PARCEL WILL BE FROM AROUND 800MB... WITH THE POTENTIAL OF 400-800 J/KG CAPE... SO IF SOMETHING CAN BE KICKED OFF THERE IS STILL A CHANCE FOR SOME THUNDER. SO... WILL MAINTAIN THE VERY LOW SLIGHT CHANCE POPS IN THE PREVIOUS FORECAST FOR THE SOUTHEAST PORTION OF THE AREA FOR THE OVERNIGHT HOURS. UPDATES TO CLOUD COVER AND TEMPERATURES WILL BE MINOR... AND WILL SIMPLY REFLECT CURRENT TRENDS. && .AVIATION.../06Z TAF ISSUANCE/ AVIATION CONCERNS ARE MINIMAL OVER THE UPCOMING 24 HOURS. ANY CHANCE FOR A SHRA OVERNIGHT SHOULD BE SOUTH OF THE AIRPORTS... WITH ONLY A FEW MID HIGH CLOUDS EXPECTED OVER THE AREA. KSTC IS SEEING SOME LIGHT FOG NOW... AND COULD CONTINUE TO SEE SOME MVFR VISIBILITIES OVER THE REMAINDER OF THE NIGHT OWING TO LIGHT WINDS AND SOME LIGHT RAIN WHICH FELL IN THAT VICINITY EARLIER TODAY. KEAU COULD ALSO SEE A BIT OF FOG LATER TONIGHT... BUT DO NOT ANTICIPATE ANYTHING TOO WIDESPREAD WITH DRIER AIR AND LOWER DEWPOINTS FILTERING IN FROM THE NORTH. THERE WILL BE A BIT OF SHEAR IN THE BOTTOM FEW THOUSAND FEET... WITH A 25KT OR SO WIND MAXIMA AROUND 2K FEET THROUGH 10Z OR SO... BUT THINGS DO NOT APPEAR FOCUSED SUFFICIENTLY TO INCLUDED WIND SHEAR IN THE TAFS. OTHERWISE... LOOK FOR LIGHT WINDS AND VFR CONDITIONS SATURDAY AND SATURDAY NIGHT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ LS/TRH mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1139 PM CDT FRI SEP 19 2008 .AVIATION.../06Z TAF ISSUANCE/ AVIATION CONCERNS ARE MINIMAL OVER THE UPCOMING 24 HOURS. ANY CHANCE FOR A SHRA OVERNIGHT SHOULD BE SOUTH OF THE AIRPORTS... WITH ONLY A FEW MID HIGH CLOUDS EXPECTED OVER THE AREA. KSTC IS SEEING SOME LIGHT FOG NOW... AND COULD CONTINUE TO SEE SOME MVFR VISIBILITIES OVER THE REMAINDER OF THE NIGHT OWING TO LIGHT WINDS AND SOME LIGHT RAIN WHICH FELL IN THAT VICINITY EARLIER TODAY. KEAU COULD ALSO SEE A BIT OF FOG LATER TONIGHT... BUT DO NOT ANTICIPATE ANYTHING TOO WIDESPREAD WITH DRIER AIR AND LOWER DEWPOINTS FILTERING IN FROM THE NORTH. THERE WILL BE A BIT OF SHEAR IN THE BOTTOM FEW THOUSAND FEET... WITH A 25KT OR SO WIND MAXIMA AROUND 2K FEET THROUGH 10Z OR SO... BUT THINGS DO NOT APPEAR FOCUSED SUFFICIENTLY TO INCLUDED WIND SHEAR IN THE TAFS. OTHERWISE... LOOK FOR LIGHT WINDS AND VFR CONDITIONS SATURDAY AND SATURDAY NIGHT. && .PREV DISCUSSION... /ISSUED 833 PM CDT FRI SEP 19 2008/ UPDATE TO FORECAST WILL MAINLY BE TO UPDATE WORDING FOR THE OVERNIGHT PERIOD... WITH MINIMAL CHANGES TO THE GOING FORECAST. FRONTAL BOUNDARY CONTINUES TO SLOWLY SAG SOUTHEASTWARD... WITH CONVECTION DISSIPATING AS DAYTIME INSTABILITY FADES. SOME ELEVATED INSTABILITY WILL REMAIN ACROSS THE SOUTHERN PORTION OF THE AREA THROUGH THE OVERNIGHT HOURS... ALTHOUGH THERE APPEARS TO BE VERY LIMITED FORCING TO GET ANY ELEVATED ACTIVITY GOING. HOWEVER... WITH THE NAM... RUC... AND LOCAL LAPSWRF KEEPING SOME NEARLY SATURATED RH IN THE 850-700MB LAYER THROUGH 12Z IT WOULD BE TOUGH TO RULE OUT AN ISOLATED SHRA/TSRA. THE BETTER FORCING... OWING TO FRONTOGENESIS AND THE ACTUAL 1000-850MB BAROCLINIC ZONE... IS FARTHER NORTH NEAR WHERE THE STRONGER CONVECTION IN NORTHEAST MINNESOTA WAS EARLIER IN THE EVENING. THIS DOES DROP SOUTHEASTWARD OVERNIGHT... ALTHOUGH IT WEAKENS AND WITH THE BOUNDARY LAYER STABILIZING... DO NOT BELIEVE IT WILL BE ABLE TO KICK OFF ANY FURTHER ACTIVITY. KMPX 00Z RAOB SUGGESTED BEST POTENTIAL FOR ANY ELEVATED PARCEL WILL BE FROM AROUND 800MB... WITH THE POTENTIAL OF 400-800 J/KG CAPE... SO IF SOMETHING CAN BE KICKED OFF THERE IS STILL A CHANCE FOR SOME THUNDER. SO... WILL MAINTAIN THE VERY LOW SLIGHT CHANCE POPS IN THE PREVIOUS FORECAST FOR THE SOUTHEAST PORTION OF THE AREA FOR THE OVERNIGHT HOURS. UPDATES TO CLOUD COVER AND TEMPERATURES WILL BE MINOR... AND WILL SIMPLY REFLECT CURRENT TRENDS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ TRH mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 1137 PM CDT FRI SEP 19 2008 .UPDATE...THINGS HAVE REALLY CALMED DOWN AS OF MID/LATE EVENING. STILL THINK THERE COULD BE A FEW SPRINKLES OVERNIGHT...AND HAVE ADDED THIS TO THE ZONES/GRIDS. HAVE ALSO ADDED PATCHY FOG MENTION WITH A FEW PLACES SEEING SOME VSBY RESTRICTIONS AS OF 11 PM. && .PREV DISCUSSION... /ISSUED 819 PM CDT FRI SEP 19 2008/ UPDATE...THE STORMS HAVE FINALLY STARTED TO SHOW SOME SIGN OF BREAKING UP AND HAVE WEAKENED SOMEWHAT AS OF 815 PM. THIS IS ABOUT ON TRACK WITH THE CURRENT THINKING OF STORMS DIMINISHING BETWEEN 01Z AND 0130Z...AND DISSIPATING BETWEEN 02Z AND 03Z. THE STORMS SEEM TO HAVE BEEN KICKED OFF IN AN AREA OF DRY MID/UPPER LEVEL AIR PER WATER VAPOR...WITH FAVORABLE LOW LEVEL INSTABILITY AND THERMODYNAMIC PROFILE/LAPSE RATES. ALSO HELPED ALONG BY FAVORABLE EFFECTIVE SHEAR AND THE FRONTAL BOUNDARY. WITH SUNSET...THE STORMS SHOULD DIMINISH NICELY DURING THE REMAINDER OF THE EVENING...ALTHOUGH WILL STILL CARRY ISOLATED MENTION THROUGH MIDNIGHT. OTHER THAN THAT...ZONES/GRIDS APPEAR TO BE IN GOOD SHAPE AND WILL LIKELY NOT MAKE MANY CHANGES TO THEM FOR THE OVERNIGHT. EXPECT TO SEND ZFP AND UPDATED GRIDS BETWEEN 830 AND 9 PM. WE WOULD GREATLY APPRECIATE CALLING ANY REPORTS INTO THE NWS THIS EVENING. PREV DISCUSSION... /ISSUED 734 PM CDT FRI SEP 19 2008/ MESOSCALE UPDATE...THE SEVERE STORM ACROSS NORTHERN LAKE COUNTY HAD MAINTAINED ITSELF NICELY OVER THE PAST FEW HOURS. WITHIN THE PAST 15 MINUTES OR SO...IT STARTED TO EXHIBIT SOME SIGNS OF DEVELOPING A HOOK ECHO...AND WE HAVE ISSUED A TORNADO WARNING. OVER THE PAST FEW MINUTES...THE STORM HAD STARTED TO UNDERGO A TRANSFORMATION YET AGAIN. THE STORM WAS MOVING THROUGH A SPARSELY POPULATED AREA...AND WE HAVE NOT HAD ANY REPORTS AS OF YET. STILL LOOKING LIKE A CHANCE OF SEVERE THROUGH 01Z...OR PERHAPS 0130Z...AND THEN DIMINISHING. MESOANALYSIS INDICATES SOME TORNADO POTENTIAL...ALTHOUGH THINK LCL LEVELS MAY BE A BIT HIGH. IF ANYONE HAS REPORTS IN THIS AREA...PLEASE RELAY THEM TO US AT THE NWS. PREV DISCUSSION... /ISSUED 648 PM CDT FRI SEP 19 2008/ MESOSCALE UPDATE...THE STORM NEAR BASSWOOD LAKE HAD STRENGTHENED CONSIDERABLY AS OF 640 PM...WITH MAX DBZ OF AROUND 70 DBZ. DEFINITELY NOT BAD FOR MID/LATE SEPTEMBER. FOR THE DAY...50 DBZ AROUND 25-28K SHOULD BE SEVERE...BUT THIS PARTICULAR STORM HAD A 50 DBZ HEIGHT OF AROUND 35K FEET. THE RUC PICKED UP ON THIS STORM ABSOLUTELY PHENOMENALLY...ALBEIT A BIT FURTHER WEST. THE RUC KEEPS THIS STUFF AROUND THROUGH AROUND 01Z...AND THEN TRIES TO DISSIPATE THE STORMS FROM 02-03Z. THIS THINKING SOUNDS GOOD WITH SUNSET APPROACHING. ADDITIONAL STORMS MAY YET DEVELOP TO THE SOUTH AND WEST OF THIS AREA...ALONG THE FRONTAL BOUNDARY...SO WILL KEEP A CLOSE EYE FOR NEW STORM DEVELOPMENT GIVEN SOME TCU DEVELOPMENT. PREV DISCUSSION... /ISSUED 620 PM CDT FRI SEP 19 2008/ UPDATE...HAVE UPDATED ZONES/GRIDS TO ADD ISOLATED STORMS ACROSS THE ENTIRE REGION WITH FRONT MOVING SOUTHEAST ACROSS THE AREA. ONE SUCH STORM DEVELOPED NORTHWEST OF BASSWOOD LAKE...AND WAS MOVING E/SE. WILL MONITOR THIS STORM IN THE EVENT IT STRENGTHENS FURTHER WHEN IT ENTERS INTO NRN LAKE/NW COOK COUNTIES. RIGHT NOW MOST OF THE ENERGY WAS NORTH OF THE BORDER...BUT WILL SOON MOVE INTO THE CWA. STRONG WIND CONVERGENCE ALONG THE FRONT COULD IGNITE A FEW MORE STORMS ALONG THE FRONT THIS EVENING. MESOANALYSIS PAGE OF SPC INDICATES MUCAPE OF AROUND 2000 J/KG WITH LITTLE INHIBITION. STEEP LAPSE RATES AND MOISTURE POOLING ALONG THE FRONT COULD LEAD TO FURTHER DEVELOPMENT IF THE STORMS ARE ABLE TO SUSTAIN THEMSELVES. FIRST THOUGHTS ARE THAT THE POTENTIAL WILL EXIST FOR A FEW STORMS TO BECOME SEVERE OVER THE NEXT FEW HOURS...BUT WILL DIMINISH RAPIDLY AS SUNSET APPROACHES. SUPERCELL COMPOSITE PARAMETER OF BETWEEN 4 AND 8 OFF THE SPC WEBSITE...SO WILL BE TAKING THE THREAT VERY SERIOUSLY THIS EVENING. PREV DISCUSSION... /ISSUED 356 PM CDT FRI SEP 19 2008/ DISCUSSION...LATEST KDLH RADAR IMAGERY SHOWS A LINE OF SCATTERED SHOWERS AND THUNDERSTORMS EXTENDING ACROSS NORTHWESTERN WISCONSIN AND PINE COUNTY THIS AFTERNOON. THIS ACTIVITY IS ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE DIGGING SE ACROSS THE AREA...PRECEDING THE COLD FRONT WHICH IS JUST ENTERING THE NW CORNER OF OUR CWA. THE PRECIPITATION WILL CONTINUE TO DISSIPATE THROUGH EARLY THIS EVENING...AND END BY MIDNIGHT. THE COLD FRONT WILL TRACK SOUTHEAST ACROSS OUR FCST AREA TONIGHT...EXITING TO THE SOUTH OF THE NORTHLAND LATE TONIGHT. HIGH PRESSURE FROM CANADA WILL THEN BUILD SOUTH OVER THE CWA TOMORROW...BRINGING COOLER TEMPERATURES AND DRY CONDITIONS. THE CENTER OF THE HIGH WILL MOVE OFF TO THE EAST OF OUR CWA ON SUNDAY...ALLOWING FOR RETURN SOUTHERLY FLOW TO DEVELOP WHICH WILL IN TURN INITIATE WAA ACROSS THE UPPER MIDWEST. AS MOISTURE AND TEMPS INCREASE ACROSS THE AREA...THE AIRMASS WILL DESTABILIZE SUNDAY THRU TUESDAY. A COLD FRONT IS PROGGED TO PROPAGATE ACROSS OUR CWA TUESDAY AND TUESDAY NIGHT...TAPPING THIS INCREASING MOISTURE AND INSTABILITY...AND BRINGING ANOTHER ROUND OF SHOWERS AND STORMS TO OUR FCST AREA. HIGH TEMPERATURES WILL DROP 10 TO 20 DEGREES ACROSS THE NORTHLAND BETWEEN TODAY TO TOMORROW. AS WINDS TURN OUT OF THE NORTHEAST...THE COOLER TEMPS WILL ESPECIALLY BE NOTICEABLE ALONG THE LAKE SUPERIOR SHORELINE. AVIATION...ISOLD -SHRA/-TSRA WILL AFFECT MAINLY KDLH AND KHYR THROUGH 21-23Z TIME FRAME AS AN UPPER LEVEL SHORT WAVE CROSSES THE WESTERN GREAT LAKES. A COLD FRONT IS FORECAST TO MOVE THROUGH NE MN THIS EVENING AND NW WI OVERNIGHT. LOOK FOR A WIND SHIFT TO THE NW AFTER FROPA. BY 12Z SATURDAY...THE WIND WILL SWING AROUND TO THE NE AS HIGH PRESSURE FROM CANADA BUILDS INTO THE AREA. && POINT TEMPS/POPS... DLH 50 58 44 62 / 20 10 10 20 INL 38 58 39 68 / 10 10 10 20 BRD 50 68 48 73 / 10 10 10 10 HYR 50 66 41 69 / 20 10 10 20 ASX 51 59 43 65 / 20 10 10 20 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ DAP mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE UPTON NY 929 AM EDT SAT SEP 20 2008 .SYNOPSIS... LARGE HIGH PRESSURE RIDGE WILL FINALLY GIVE WAY TO A WEAK COLD FRONT LATE SUNDAY. THIS FRONT WILL SLOWLY MOVE THROUGH SUNDAY NIGHT AND MONDAY...THEN ANOTHER AREA OF HIGH PRESSURE WILL SETTLE OVER THE AREA THROUGH MID WEEK. A DEVELOPING COASTAL LOW MAY APPROACH THE AREA LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MORNING SOUNDING SHOWS VERY STABLE ATMOSPHERE WITH STRONG SUBSIDENCE ALOFT AS SEEN ON WATER VAPOR IMAGERY AS WELL. LOW LEVEL MOISTURE BELOW THE INVERSION SEEN ON SOUNDING AND ACARS/TAMDAR PROFILES PRODUCING STRATUS SOUTH OF LONG ISLAND...BUT SPILLING UP INTO QUEENS AND NASSAU. DUE TO HEATING...FEEL THAT RUC AND NAM SOUNDINGS ARE CORRECT IN MIXING THESE CLOUDS OUT TO SCATTERED. WITH A GOOD DEAL OF SUNSHINE THIS AFTERNOON...TEMPERATURES WILL WARM A FEW DEGREES HIGHER THAN WHAT WAS OBSERVED YESTERDAY DUE TO WEAKER EASTERLY LOW LEVEL FLOW...AND THUS DEEPER MIXED LAYER. MOS/LAV NUMBERS CONTINUE TO LOOK GOOD. SEE TIDE SECTION BELOW FOR THE MINOR COASTAL FLOOD CONCERN. MODERATE RIPS AT THE OCEAN BEACHES. SEE MARINE SECTION. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... AS THE RIDGE SETTLES OVER THE AREA AND WEAK FRONT APPROACHES FROM THE NORTHWEST...LOW LEVEL EASTERLY FLOW WILL END. AS SUCH...SKIES WILL REMAIN CLEAR TONIGHT. UPPER TROUGH THAT REMAINS WELL TO THE NORTH WILL SLOWLY PROGRESS EAST ACROSS SOUTHEAST CANADA. AT THE SURFACE...WEAK FRONT BETWEEN RIDGE TO THE SOUTH AND NEXT AREA OF HIGH PRESSURE UP IN CENTRAL CANADA WILL APPROACH THE REGION. THIS WILL OCCUR LATER SUNDAY AND SUNDAY NIGHT. AN INCREASE IN LOW LEVEL MOISTURE POOLING AHEAD OF FRONT...AND WEAK FORCING COULD TRIGGER AN ISOLATED SHOWER OR SPRINKLE. BEST TIME FOR ANY PRECIP LOOKS TO BE SUNDAY NIGHT INTO EARLY MONDAY. THEN RIDGE PREDOMINATES LATER MONDAY...AND ATMOSPHERE DRIES OUT QUICKLY. TEMPS...SEASONABLE NIGHT TONIGHT...THEN WARMER AIR SWEEPS IN AHEAD OF SFC FRONT SUNDAY. 950 HPA TEMPS WARM FROM 12-13C SATURDAY (EASTERLY LOW LEVEL FLOW) TO 18-19C SUNDAY. EXPECTED CLOUD COVER SUNDAY NIGHT WILL KEEP READINGS A TAD HIGHER THAN PREVIOUS NIGHTS...BUT MONDAY SHOULD BE QUITE COOL AS CLOUDS LINGER AND NORTHEAST FLOW SETS UP ONCE AGAIN. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... BUILDING HIGH PRESSURE WILL RESULT IN ANOTHER STRETCH OF DRY WEATHER THROUGH AT LEAST THU. PERSISTENT NE-E CAN BE EXPECTED THROUGH THE PERIOD AS THE HIGH REMAINS ANCHORED NORTH OF THE AREA. THERE CONTINUES TO MODEL UNCERTAINTY ABOUT HOW CLOSE A LOW OFF THE SE COAST WILL APPROACH IN THE THURSDAY NIGHT THROUGH SATURDAY TIME FRAME. LATEST GUIDANCE SUGGESTS THAT RIDGING WILL REMAIN FIRMLY IN PLACE DURING THE PERIOD...RESULTING IN A MORE EASTERLY TRACK OF THE SURFACE LOW. GIVEN UNCERTAINTY REGARDING THIS SURFACE LOW...HAVE KEPT POPS LOW FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT. && .AVIATION /13Z SATURDAY THROUGH WEDNESDAY/... OVERALL...VFR WITH HIGH PRESSURE. PAN-CAKE STRATO-CU DUE TO SURFACE HEATING WILL BE BROKEN AT TIMES THIS AM ON LONG ISLAND. BASES OF 025 EARLY RISE BY THIS AFTERNOON. WINDS ARE TRICKY AS THE REGION IS IN A TUG OF WAR BETWEEN A RIDGE OF HIGH PRESSURE THAT RUNS ALONG AND JUST INSIDE OF THE I-95 CORRIDOR...AND OFFSHORE LOW OVER THE ATLANTIC. WILL KEEP A GENERAL NE-E FLOW ACROSS THE AREA....AS I EXPECT THE RIDGE AXIS TO REMAIN TO OUR NORTH...WITH JUST ENOUGH INFLUENCE FROM THE OFFSHORE LOW TO KEEP THE FLOW FROM TURNING MORE ONSHORE. SPEEDS STAY LESS THAN 10 KT. NYC METRO WINDS...LGA EXPECTED TO HOLD ITS TYPICAL NE DIRECTION THROUGH THE AFTERNOON WHILE JFK FLIPS OVER TO SOUTHERLY SEA BREEZE. KEWR MAY BE MORE VARIABLE...BUT FORECASTING A MORE SOUTHERLY FLOW BASED ON LATEST DATA AND COLLABORATION WITH ZNY. LOW CONFIDENCE ON TIMING OF DIRECTION/RUNWAY CONFIG CHANGE AT KEWR. THEREAFTER...PRESSURE PATTERN...AND AS A RESULT WINDS...BECOME LIGHT AND ERRATIC THIS EVENING...BEFORE A BIT BETTER DEFINED NORTHWEST FLOW DEVELOPS AROUND OR AFTER MIDNIGHT. EXPECT A LIGHTER ONSHORE FLOW AT SEA BREEZE TERMINALS WITH VRB AROUND 5 KT ELSEWHERE FROM 23-00Z THROUGH 03-05Z. OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY...HI PRES OVER THE REGION THROUGH WED WITH MAINLY VFR CONDITIONS. A WEAK CDFNT SUN NIGHT/MON TIME FRAME. ATTM FRONT LOOKS DRY WITH A CHANCE FOR MVFR CIGS AT TIMES WITH NELY FLOW BEHIND THE FRONT. && .MARINE... THE AREA REMAINS SANDWICHED BETWEEN INLAND RIDGE OF HIGH PRESSURE AND AN OFFSHORE LOW EAST OF THE CAROLINAS. THIS WILL KEEP A FAIRLY PERSISTENT NE-E FLOW IN PLACE. WINDS WILL CONTINUE TO GRADUALLY DIMINISH TODAY...BUT SEAS SHOULD REMAIN ABOVE SCA THRESHOLDS INTO SUN. HAVE UNDERCUT WAVEWATCH III...BUT WILL KEEP 4 TO 6 FT ON OCEAN WATERS TODAY AND 3 TO 5 FT TONIGHT INTO SUNDAY. THE PERSISTENT EASTERLY COMPONENT TO THE WINDS...A WEAK EASTERLY SWELL AND LARGE BREAKING WAVES WILL RESULT IN A MODERATE RISK OF RIP CURRENTS ALONG NEW YORK ATLANTIC BEACHES TODAY. AN EXTENDED PERIOD OF SCA CONDITIONS IS LIKELY TO RETURN TO THE OCEAN WATERS AFTER COLD FROPA ON MON...AS THE AREA ONCE AGAIN BECOMES SANDWICHED BETWEEN ANOTHER STRONG INLAND HIGH...AND A COASTAL LOW DEVELOPING ALONG THE SOUTHEAST COAST...WITH A PERSISTENT NE-E FLOW OVER THE WATERS KEEPING MAX OCEAN SEAS 5+ FEET. && .HYDROLOGY... NO SIGNIFICANT RAINFALL EXPECTED. && .TIDES/COASTAL FLOODING... LATEST DATA SHOWING WATER LEVELS ARE BETWEEN 0 AND 0.75 FT ABOVE ASTRONOMICAL. NO PROBLEMS FORESEEN - THOUGH WILL CONTINUE TO MONITOR. THE TIDE CYCLE OF CONCERN IS MIDDAY HIGH TIDE CYCLE...WHICH IS THE HIGHER OF THE TWO DAILY HIGH TIDES. ASTRONOMICAL TIDES REMAIN HIGH...AND A DEPARTURE OF ONLY ABOUT 1.0 FT IS NEEDED TO REACH MINOR COASTAL FLOODING BENCHMARKS. FEEL THAT WE WILL FALL SHORT OF THIS TODAY DUE TO THE COMBINATION OF A MORE NORTHEAST FLOW THIS MORNING AND A DECREASING WIND SPEED AS THE DAY PROGRESSES. THE DEPARTURES FOR THE HIGH TIDE CYCLE OVERNIGHT WERE LESS THAN YESTERDAY...AND EXPECT THE DECREASING DEPARTURE THEME TO CONTINUE. MOST LOCALES WILL REMAIN SAFELY BELOW (0.5 FT OR MORE) MINOR BENCHMARKS. HOWEVER...WE COULD COME CLOSE IN THE NASSAU SOUTH SHORE BACK BAYS. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 PM EDT SUNDAY FOR ANZ350-353-355. && $$ SYNOPSIS...PW NEAR TERM...JST/PW SHORT TERM...PW LONG TERM...MAS AVIATION...JST MARINE... HYDROLOGY... TIDES/COASTAL FLOODING... ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1025 AM EDT SAT SEP 20 2008 .SHORT TERM.../THE REST OF TODAY/...UPDATED CHANCE OF SHOWERS TODAY RESTS ON HOW STRONG IS THE CAP BETWEEN 650 AND 750 MB. 12Z RUC/06Z NAM WOULD SUGGEST THAT ENOUGH INSTABILITY IS PRESENT ALONG WITH THE APPROACHING VERY WEAK SHORTWAVE ASSOCIATED WITH SOME SHOWERS CURRENTLY IN MIDDLE TN FOR AT LEAST ISOLATED OR SCATTERED SHOWERS AND EVEN THUNDER. THIS CAP IN THE 12Z NAM IS SLIGHTLY STRONGER THAN THE 06Z RUN BUT WITH ENOUGH MOISTURE TO OVERCOME IT FOR POSSIBLE AFTERNOON CONVECTION. 06Z GFS SHOWS A MORE ROBUST CAP AND LESS MOISTURE WHILE 12Z BNA SOUNDING SHOWED MORE AND DEEPER MOISTURE THAN THIS MODEL INDICATED. GIVEN THAT WE SHOW A CHANCE OF SHOWERS FOR OUR WEST PORTION WHILE NEARBY LOCATIONS DO NOT INDICATE THAT MUCH CHANCE CANNOT JUSTIFY INCREASING POPS...BUT WILL MONITOR FOR UPDATE. CONVECTIVE TEMPERATURES ARE GENERALLY IN THE MID/UPPER 70S SO LOWERED MAX TEMPERATURES 2-3 DEGREES. SHOULD HAVE AN EARLIER START TO CONVECTIVE CLOUDS ALONG WITH CONVECTIVE DEBRIS FROM DECAYING SHOWERS FROM TN TO KEEP TEMPERATURES DOWN SLIGHTLY FROM YESTERDAYS VALUES. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TODAY THROUGH MONDAY/ EARLY THIS MORNING...SUBTROPICAL RIDGE EXTENDS FROM THE GULF OF MEXICO EAST INTO THE WESTERN ATLANTIC. WELL TO THE NORTH...RATHER FAST WESTERLIES WERE GENERALLY NORTH OF THE US CANADIAN BORDER WITH A TROUGH MOVING THROUGH THE JAMES BAY/HUDSON BAY REGION DOWN INTO ONTARIO AND QUEBEC. AN UPPER LEVEL LOW WAS OVER THE MID MS VALLEY...NEAR THE CONFLUENCE OF THE OH AND MS RIVERS. AT THE SFC...AN EXPANSIVE RIDGE OF HIGH PRESSURE EXTENDS SOUTH INTO THE APPALACHIANS FROM THE NORTHEASTERN UNITED STATES. THROUGH SUNDAY...THE WEAK CLOSED LOW IS FORECAST BY THE MODELS TO REMAIN NEARLY STATIONARY TO THE WEST OF THE AREA LARGELY AND THEN DAMPEN OUT TO END THE PERIOD. IN FACT...THIS WILL LEAD TO RISING HEIGHTS AT THE END OF THE PERIOD...AND BOTH THE GFS AND NAM INDICATE SW/V UPPER RIDGING WORKING BACK ACROSS THE AREA ON MONDAY. A WEAK BOUNDARY WILL DISSIPATE AS IT MOVES SOUTH OF THE GREAT LAKES ON SUN NIGHT INTO MONDAY...AS THE NEXT REINFORCING AREA OF HIGH PRESSURE WORKS INTO EASTERN/CANADA AND THE NORTHEASTERN UNITED STATES IN CONCERT WITH THE RISING HEIGHTS OVER THE GREAT LAKES AND OH VALLEY. REGIONAL SFC OBSERVATIONS REVEAL HIGHER DEWPOINTS CURRENTLY NEAR AND WEST OF THE INTERSTATE 75 CORRIDOR...OR GENERALLY CLOSER TO THE UPPER LEVEL SYSTEM. LOW LEVEL FLOW FURTHER EAST IS SOUTHEAST OR DOWNSLOPE... THOUGH RECENT VWP INDICATES IT IS BECOMING MORE SOUTHERLY. THE FINER RESOLUTION NAM AS WELL AS THE 21Z SREF GENERALLY INDICATE THAT THE DOWNSLOPE FLOW WILL WEAKEN WITH MORE SOUTHERLY TO WEAK WESTERLY FLOW OVER THE WESTERN AREAS...ALLOWING FOR LIMITED MOISTURE ADVECTION. THEN NAM AND SREF DEVELOP A WEAK TROUGH OF LOW PRESSURE/AREA OF CONVERGENCE NEAR THE OH RIVER AND EXTENDING EAST IN THE BLUEGRASS REGION. WITH BETTER MOISTURE IN PLACE AND EXPECTED TO REMAIN BETTER OVER THE WESTERN COUNTIES...A FEW SHOWERS CANNOT BE RULED OUT THIS AFTERNOON OVER THIS REGION AS CAPPING WILL BE WEAKER THERE CLOSER TO THE CLOSED LOW THAN IN AREAS FURTHER TO THE EAST. AREAS IN OR NEAR WHERE SHOWERS OCCURRED ON FRI EVENING CANNOT BE RULED OUT FOR POSSIBLE VERY ISOLATED SHOWERS ON SAT DUE TO DIFFERENTIAL HEATING BOUNDARIES...BUT KEPT THESE AREAS OF FAR SE KY DRY FOR NOW AS THEY APPEAR TO BE CAPPED. THE CHANCE FOR SHOWERS WILL WANE WITH THE LOSS OF DAYTIME HEATING...BUT THE CAP AGAIN APPEARS AS IF IT WILL BE WEAKER ON SUN OVER THE FAR SW COUNTIES NEAR LAKE CUMBERLAND AND AGAIN INCLUDED A SLIGHT CHANCE POP FOR THESE AREAS. THE REMAINDER OF THE PERIOD WILL BE DRY AS HEIGHTS RISE. ANY MOISTURE FROM THE DYING BOUNDARY ON MON SHOULD ONLY LEAD TO AN INCREASE IN SHALLOW AFTERNOON CU OVER NE KY. AS FOR TEMPERATURES...THE ONGOING DROUGHT CONTINUES TO HAVE AN EFFECT AND LOZ AND JKL AGAIN VERIFIED WARMER THAN MOS GUIDANCE FOR FRI MAX T AND EXPECT THIS TO CONTINUE FOR MAX T THROUGH THE SHORT TERM AT BOTH SITES. GUIDANCE AT SME WAS GENERALLY FOLLOWED...THOUGH WITH THE RIDGE BUILDING IN ON MON...THE WARMER MAV MAX TEMP APPEARED IN ORDER. OTHERWISE...RIDGE/VALLEY TEMP SPLITS AS WELL AS PATCHY FOG BETWEEN 6Z AND 13Z EACH NIGHT AND EARLY EACH MORNING WILL CONTINUE. MAV GUIDANCE AND NAM DATA BOTH INDICATE FALLING DEWPOINTS ON SUN AS NE FLOW USHERS IN SOME DRIER AIR. THIS WILL LIKELY LEAD TO THE COOLEST VALLEY READINGS DURING THE PERIOD ON MON AM...WHERE THE NORMALLY COLD SPOTS SHOULD FALL INTO THE UPPER 40S. .LONG TERM.../MONDAY NIGHT THROUGH FRIDAY/ FOR THE EXTENDED...THE LONGWAVE PATTERN HOLDS LITTLE HOPE FOR PCPN MAKING INTO EAST KENTUCKY AS THE RIDGE...MENTIONED ABOVE...TILTS NORTHEASTWARD WHILE THE WESTERN TROUGH PLOWS ACROSS SOUTHERN CANADA AND THE NORTHERN PLAINS. AS THE UPPER PATTERN THUS FLATTENS OUT... RIDGING WILL HOLD ON STRONG OVER THE SOUTHERN 2/3RDS THE NATION WHILE THE WESTERLIES RACE BY WELL TO THE NORTH. THE ECMWF FROM 00Z/19 WAS FOLLOWED CLOSEST GIVEN ITS RECENT PERFORMANCE AND REASONABLE SOLUTION. ONE INTERESTING ASPECT OF IT/S SOLUTION...THOUGH ONE NOT SO MUCH RESOLVED IN THE GFS...WAS THE DEVELOPMENT OF AN UPPER LOW OFF THE SOUTHEAST COAST FROM MIDWEEK ON. THIS APPEARS TO FURTHER AMPLIFY THE RIDGE TO ITS WEST...HAMMERING HOME THE IDEA OF A DRY EXTENDED FOR OUR AREA. A QUICK PEEK AT THE 12Z ECMWF SEES IT CONTINUING THIS TREND. FOR SENSIBLE WEATHER...IT IS AS IF THE WEATHER PATTERN IS COMING UP WITH NEW WAYS TO KEEP EAST KENTUCKY DRY. RIDGING ALOFT WILL MAKE ANY FRONT THAT MANAGES TO COME THROUGH HERE A DRY PASSAGE...AN UPPER LOW...AND ITS WEAK SFC REFLECTION...TO THE WEST WILL FALL APART BEFORE GETTING CLOSE ENOUGH TO GIVE US RAIN...AND FINALLY A POTENTIAL EAST COAST SYSTEM LATE IN THE PERIOD WILL ONLY SERVE TO KEEP OUR AREA IN SUBSIDENCE WHILE STRENGTHENING THE UPPER RIDGING JUST OFF TO OUR WEST. IN THIS REGIME...AM LOATH TO FORECAST ANY PCPN. AS A RESULT...A PERSISTENCE FORECAST WAS CARRIED THROUGH FRIDAY WITH ADJUSTMENTS MADE FOR THE VAGARIES OF DRY FRONTS AND VARIOUS HIGH PRESSURE SYSTEMS PASSING THROUGH. THE ONLY HOPE I SEE FOR MUCH NEEDED RAIN IS THE SEASONAL EXPECTATION OF THE WESTERLIES EVENTUALLY PUSHING FAR ENOUGH SOUTH TO AFFECT US...BEYOND THE EXTENDED. UNTIL THAT HAPPENS THOUGH...DRY AND SEASONALLY WARM TEMPERATURES WILL CONTINUE TO DOMINATE THE FORECAST. && .AVIATION.../12Z TO 12Z/ VFR CONDITIONS AND LIGHT WINDS WILL PREVAIL THROUGHOUT THE PERIOD...WITH ONLY SOME OPAQUE HIGH CLOUDS AND OCCASIONAL HIGHER BASED CU AT AROUND 6K FEET TRAVERSING THE AREA. A STRAY SHOWER OR TWO WILL BE POSSIBLE NEAR THE INTERSTATE 75 AND 64 CORRIDORS BETWEEN 18 AND 22Z...HOWEVER GIVEN THE ISOLATED NATURE OF THESE...WILL NOT INCLUDE MENTION AT SME AND LOZ. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...JP/GV LONG TERM....GREIF AVIATION...GEOGERIAN ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1033 AM EDT SAT SEP 20 2008 .SYNOPSIS... HIGH PRESSURE WILL PERSIST OVER THE REGION THROUGH THE WEEKEND RESULTING IN COOL AND DRY CONDITIONS ACROSS CENTRAL NORTH CAROLINA. && .NEAR TERM /THROUGH THIS AFTERNOON/... AS OF 1030 AM SATURDAY... DIFFICULT CLOUD AND TEMPERATURE FORECAST FOR THE AFTERNOON AS VISIBLE IMAGERY SHOWS A BAND OF MOSTLY CLOUDY SKIES FROM NEAR AND JUST WEST OF RZZ...THROUGH THE TRIANGLE...TO AROUND FAYETTEVILLE... WITH CONSIDERABLE BREAKS TOWARD ROCKY MOUNT AND MOSTLY SUNNY CONDITIONS TOWARD THE WEST. WHILE THE KGSO SOUNDING WAS DRY WITH PRECIPITABLE WATER VALUES UNDER A HALF INCH...THE KMHX SOUNDING HAD PRECIPITABLE WATER VALUES OVER AN INCH MOSTLY DUE TO AMPLE MOISTURE BENEATH THE SUBSIDENCE INVERSION AROUND 750MB. IN THE NORTHEAST FLOW...OBVIOUSLY SOME OF THIS MOISTURE WAS SPREADING WEST ACROSS THE PIEDMONT...BUT WITH NUMEROUS BREAKS PARTICULARLY ALONG INTERSTATE 95. THE RUC WAS NOT HANDLING THE LOW-LEVEL MOISTURE VERY WELL...BUT THE NAM WAS A LITTLE BETTER...SHOWING FOR THE EARLY AFTERNOON WIDESPREAD...HIGH 925MB MOISTURE...AND BY 21Z ONLY A THIN RIBBON OF 925MB MOISTURE FROM ACROSS THE NORTHERN COASTAL PLAIN THROUGH THE TRIANGLE. PROBABLY THE BEST FORECAST FOR CENTRAL AND EASTERN ZONES IS VARIABLE CLOUDINESS...THOUGH THINK WITH SOME MIXING SKIES WILL TREND TOWARD PARTLY SUNNY ESPECIALLY SINCE THERE WERE ALREADY BREAKS NOTED ON VISIBLE IMAGERY. IN WESTERN ZONES...THE NAM WAS ON TARGET WITH A BAND OF UPPER MOISTURE TOWARD THE FAR EASTERN PERIPHERY OF THE UPPER LOW OVER MISSOURI...AND SCATTERED CLOUDS ASSOCIATED WITH THIS SHOULD MOVE EAST WITH THE EXPECTATION BEING MOSTLY SUNNY CONDITIONS THERE FOR THE BULK OF THE AFTERNOON. LOWERED TEMPERATURES IN MOST PLACES CENTRAL AND EASTERN ZONES AROUND A CATEGORY ANTICIPATING MORE CLOUDS...THOUGH THERE WILL BE LOCAL AREAS IN ZONES THAT WILL CERTAINLY REACH THE HIGHER END OF THE TEMPERATURE RANGE DUE TO BREAKS. IN FULL SUN...1000-850MB THICKNESSES WOULD SUPPORT NEAR 75...WHICH IS IN CONCERT WITH THE LAV AND BLEND OF MOS. GRADIENT WILL RELAX SLIGHTLY THIS AFTERNOON... LEAVING WINDS FROM AROUND 10 TO 15 MPH EVEN WITH MIXING. THANKS TO AKQ...ILM...AND MHX FOR COLLABORATION THIS MORNING. && .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... AS OF 325 AM SATURDAY... TONIGHT AND SUNDAY: AS UPPER LEVEL FLOW INCREASES FROM THE WEST... THERE WILL BE SOME INCREASE IN HIGH LEVEL CLOUDINESS OVERNIGHT. THE SURFACE FLOW BECOMES SOMEWHAT RELAXED AS HIGH PRESSURE CENTER SETTLE OVER CENTRAL NORTH CAROLINA SUNDAY. OVERNIGHT CLOUDS SHOULD AID IN HOLDING LOWS IN THE MID 50S. LESS CLOUDINESS SUNDAY WILL ALLOW THE MERCURY TO INCH UP A COUPLE DEGREES AS THICKNESSES INCREASE OVER THE REGION. HIGHS WILL IN THE MID 70S TO AROUND 80. SUNDAY NIGHT THROUGH MONDAY NIGHT: STRONGER HIGH PRESSURE WILL BUILD SOUTH FROM CANADA FOR THE FIRST OF THE WEEK. AT THE SAME TIME A BROAD UPPER LEVEL TROUGH WILL WORK ITS WAY EAST. THE MAIN CHANGES WE WILL EXPERIENCE WILL BE AN INCREASE IN HIGHS MONDAY AS THICKNESSES RANGE IN THE 1390 TO 1395 RANGE... THEY WILL BE IN THE UPPER 70S TO LOWER 80S. AS THE HIGH BUILDS SOUTH THE GRADIENT WILL TIGHTEN... INCREASES WINDS ESPECIALLY OVER THE EAST. LOWS SUNDAY NIGHT WILL BE I THE UPPER 50S AND AROUND 60MONDAY NIGHT.A DRY FORECAST WILL BE MAINTAINED THROUGH THE PERIOD. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 345 AM SATURDAY... GUIDANCE IS IN GOOD AGREEMENT THROUGH WEDNESDAY ON MAINTAINING STRONG SFC RIDGING INTO NORTH CAROLINA FROM A PARENT HIGH OVER NEW ENGLAND. THIS WILL CONTINUE TO PROVIDE THE REGION WITH A COOL NORTHEAST LOW LEVEL FLOW. WHILE PERIODS OF STRATUS/STRATOCUMULUS IS POSSIBLE IN THIS TYPE OF PATTERN...THERE APPEAR TO BE NO LIFTING MECHANISMS TO GENERATE ANY PRECIPITATION AS A SHORTWAVE RIDGE WILL BE MOVING THROUGH DURING THIS TIME. THEREFORE...A DRY FORECAST WILL PREVAIL WITH TEMPS CONTINUING TO BE VERY COMFORTABLE. HIGHS IN THE MID TO UPPER 70S AND LOWS IN THE MID TO UPPER 50S. MODEL SOLUTIONS BEGIN TO DIFFER BY THE END OF THE WEEK. THERE IS CONSIDERABLE UNCERTAINTY REGARDING POTENTIAL SFC CYCLOGENESIS OVER THE WESTERN ATLANTIC. THERE DOES APPEAR TO BE PIECES IN PLACE TO SUPPORT A LOW DEVELOPING. FIRST...THERE WILL BE A LINGERING BAROCLINIC ZONE POSITIONED FAIRLY NEAR THE GULF STREAM DUE TO THE PERSISTENT SFC RIDGING INLAND OVER THE CAROLINAS. SECONDLY...MOST GUIDANCE SUGGESTS THAT A VORTICITY MAX BECOMES SEPARATED FROM A DEEP TROUGH MOVING AWAY FROM THE NORTHEAST STATES AND EASTERN CANADA. THIS PIECE OF ENERGY LINGERS A FEW HUNDRED MILES OFF OF THE CAROLINA COASTS WHILE A 70-80 KT SUBTROPICAL JET BEGINS TO NOSE IN FROM THE SOUTHWEST. WHILE MOST GUIDANCE DEVELOPS A LOW IN RESPONSE TO ALL OF THE ABOVE...THE EXACT TIMING OF THE DEVELOPMENT AND THE EVENTUAL LOW TRACK ARE VERY MUCH UP IN THE AIR. THE OPERATIONAL GFS IS THE LEAST AGGRESSIVE WITH DEVELOPMENT...BUT IS COUNTERED BY SEVERAL OF ITS ENSEMBLE MEMBERS WHICH LEANS TOWARD THE ECMWF SOLUTION OF A LOW DEVELOPING OFF THE NC COAST BY FRIDAY. THE CANADIAN ACTUALLY RETROGRADES THE LOW INTO SOUTH CAROLINA BY FRIDAY. THE CURRENT FORECAST HAS SLIGHT CHANCE POPS FOR THE END OF THE WEEK IN THE EASTERN ZONES AND SEE NO REASON TO CHANGE THEM GIVEN THE UNCERTAINTY. WILL ALSO TREND TEMPS CLOSE TO CLIMO GIVEN THE CONTINUED PRESENCE OF SFC RIDGING INTO THE AREA FROM THE NORTHEAST. LOOKING AT GENERALLY MID TO UPPER 70S FOR HIGHS AND UPPER 50S FOR LOWS. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... AS OF 1030 AM SATURDAY... BASED ON CURRENT TRENDS...EXPECT MVFR CIGS TO CONTINUE THROUGH THE MORNING INVOF RDU/RWI/FAY...ALTHOUGH THERE COULD BE PERIODS WHERE SKIES BRIEFLY SCATTER OUT. BY MIDDAY...EXPECT A MORE WIDESPREAD STRATOCUMULUS DECK TO DEVELOP DUE TO DAYTIME HEATING. CIGS SHOULD GRADUALLY LIFT TO VFR BY MID AFTERNOON...BUT MVFR CONDITIONS MAY LAST MUCH OF THE DAY AT RDU/FAY/RWI. FURTHER WEST AT INT/GSO...LOW LEVEL MOISTURE NOT AS ABUNDANT SO ONLY ANTICIPATING SCATTERED STRATOCU WITH SCATTERED HIGH CLOUDS THIS MORNING. NORTHEAST WINDS AROUND 10 KT WILL PERSIST FOR MUCH OF THE DAY. SOME GUSTS OF 15-18KT POSSIBLE THIS MORNING AS THE LOW LEVEL JET MIXES OUT AND SOME OF THOSE HIGHER WINDS ARE TRANSPORTED TO THE SFC. THE STRATOCUMULUS SHOULD SCATTER OUT THIS EVENING WITH VFR CONDITIONS PREVAILING. THE LOW LEVEL FLOW WEAKENS AND DRIES OUT BY EARLY SUNDAY MORNING...SO CURRENTLY NOT ANTICIPATING ANY CEILING OR LOW LEVEL WIND SHEAR CONCERNS. VFR CONDITIONS SHOULD PERSIST THROUGH MIDWEEK...EXCEPT FOR SOME LOW STRATUS POSSIBLE TUESDAY MORNING. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...RHJ NEAR TERM...DJF SHORT TERM...RHJ LONG TERM...JFB AVIATION...DJF/JFB nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 1042 AM CDT SAT SEP 20 2008 .UPDATE... NO REAL CHANGES TO PRIOR THINKING REGARDING AFTN/EVE STORM CHANCES. UPDATED FORECAST OUT TO REMOVE MORNING WORDING AND TWEAK RAIN CHANCES A BIT. AT 15Z...COLD FRONT RUNNING FROM WAUSAU/MEDFORD AREAS WEST TO SRN TC METRO TO REDWOOD FALLS/NEW ULM MN AREAS. LEADING ACCAS BAND ON EDGE OF MID LEVEL INSTABILITY HAS PUT ON A NICE VIRGA SHOW AS IT HAS SAGGED SOUTH INTO NERN IA/SWRN WI THIS MORNING. STILL SOME UNCERTAINTY INTO AFTN/EVE ON COVERAGE OF SHOWERS/STORMS ALONG SLOWLY SAGGING COLD FRONT...WHICH WON`T MOVE TOO MUCH MORE SOUTHWARD. LATEST RUNS OF VERY HI-RES SHORT TERM GUIDANCE /RUC13...LOCALLY RUN RUC13-BASED ARW-WRF...AND GFS-BASED ARW-WRF/ ALL ARE VERY STINGY ON SHRA/STORM DEVELOPMENT...WHILE 20.12Z RUN OF NAM-WRF /NMM/ REALLY RAMPED THINGS UP...WHICH ALIGNS WELL WITH NMM-BASED SPC WRF. NSSL WRF LIES IN BETWEEN WITH SCT COVERAGE ALONG THE LENGTH OF FRONT DEVELOPING MOSTLY IN 21-00Z TIMEFRAME. CONTINUITY/SREF FAVORS SOMETHING LESS THAN RECENT NAM-WRF /NMM/ BUT PROBABLY MORE ROBUST THAN RUC13 AND OTHER HI-RES RUNS THIS MORNING. PLENTY OF INSTABILITY /MLCAPES OVER 1000 J/KG/ VIA STEEP LAPSE RATE AND FRONTAL CONVERGENCE...WHILE WEAK...SHOULD PROVE SUFFICIENT FOR INITIATION AS CONVECTIVE TEMPS ARE BREACHED BY MID AFTN. NO SHEAR...IN FACT...WINDS ONLY 7-10KFT UP ARE NIL...WITH RIDGING BUILDING IN. STORMS WILL HAVE VERY SLOW SOUTHWARD DRIFT. THUS...LARGE SCALE DOESN/T SUPPORT HIGHER RAIN CHANCES RIGHT NOW. BEST FRONTAL PUSH DOES SEEM TO BE EAST OF MS RIVER SO DID INCREASE RAIN CHANCES THERE A BIT. INITIAL UPDRAFTS MAY BE ROBUST GIVEN CAPE IS AMPLE...BUT STORMS TO BE VERY AIRMASS IN NATURE. MAY SEE A PEA HAIL REPORT BUT NO SVR STILL EXPECTED. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ BINAU wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 307 PM CDT SAT SEP 20 2008 .DISCUSSION... 307 PM CDT MAIN SHORT TERM ISSUE IS WITH PRECIP CHANCES INTO THIS EVENING WITH WEAK CUT OFF UPPER LOW CURRENTLY VICINITY KSTL. WEAK SPEED MAX/SHEARED VORTICITY MAXIMA ROTATING INTO SOUTHERN CWA THIS AFTERNOON...ATOP WEAKLY UNSTABLE BOUNDARY LAYER WHERE SPC/RUC MESO DATE INDICATES MLCAPES AROUND 1000 J/KG AND NO CIN. LOW LEVEL WIND FIELD RATHER WEAK ACROSS THE AREA...THOUGH AFTERNOON VIS SATELLITE IMAGERY INDICATES AREA OF ORGANIZED WEAK LOW LEVEL CONVERGENCE ROUGHLY ALONG AN AXIS FROM KPIA...KBMI TO KCMI WITH SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING AND MOVING NORTH/NORTHWEST INTO FAR SOUTHERN PORTIONS OF WFO CHICAGO CWA. EXPECT THAT THIS CONVECTIVE ACTIVITY WILL BE HIGHLY DIURNAL IN NATURE AND WILL FADE RATHER QUICKLY THIS EVENING...THOUGH WILL LIKELY HAVE TO HAVE A MENTION OF SCATTERED SHOWERS/THUNDER FOR AT LEAST SOUTHERN PARTS OF THE FORECAST AREA THROUGH SUNSET. A COUPLE OF THE STRONGEST CELLS HAVE SHOWN WEAK HAIL SPIKES IN REFLECTIVITY DATA THIS AFTERNOON...AND SLOW CELL MOVEMENT TO THE NORTH AT 5 MPH OR LESS MAY ALLOW BRIEF HEAVY DOWNPOURS...THOUGH ACTIVITY SHOULD WEAKEN WITH LOSS OF INSOLATION BY EARLY EVENING. FARTHER NORTH...COLD FRONT SAGGING THROUGH CENTRAL WISCONSIN THIS AFTERNOON PROGGED TO ENTER THE FORECAST AREA LATE EVENING/OVERNIGHT. MODELS CONTINUE TO SQUEEZE OUT PRECIP ALONG/AHEAD OF THIS BOUNDARY THIS EVENING ACROSS SOUTHERN WI/LM AND INTO NORTHERN IL...THOUGH LOW LEVEL MOISTURE CONVERGENCE CURRENTLY FAIRLY WEAK AHEAD OF FRONT AND RUC ANALYSIS DEPICTS 75-150 J/KG OF CIN. ANY CONVECTION ALONG FRONT ALSO EXPECTED TO BE HIGHLY DIURNAL WITH BEST DEEPER LAYER FORCING WELL TO THE NORTH WITH UPPER WAVE OVER ONTARIO AND FAR NORTHERN LAKES. TIMING OF FRONT WELL AFTER SUNSET SUGGESTS MINIMAL PRECIP THREAT WITH FRONT. POTENTIAL FOR SCATTERED CONVECTION REMAINS AN ISSUE ON SUNDAY...AS UPPER CIRCULATION FORECAST TO SLOWLY DRIFT NORTH/NORTHWEST AND WEAKEN AS IT MERGES WITH NORTHERN STREAM SHORT WAVE ENERGY CURRENTLY PROPAGATING THROUGH CENTRAL ROCKIES. MODELS CONTINUE TO INDICATE WEAK VORTICITY ADVECTION ASSOCIATED WITH WEAKENING UPPER CIRCULATION AS WELL AS SIMILAR LOW LEVEL INSTABILITY OF AROUND 1000 J/KG AND NO CIN. IN ADDITION...FRONTAL BOUNDARY SETTLES ACROSS WESTERN/SOUTHERN CWA WHICH PERHAPS WILL PROVIDE SOME LOW LEVEL CONVERGENT FOCUS FOR AFTERNOON CONVECTIVE DEVELOPMENT. WITH THIS IN MIND WILL CARRY SOME LOW CHANCE AFTERNOON POPS MAINLY WEST/SOUTH PARTS OF CWA SUNDAY AFTERNOON. UPPER WAVE BECOMES FULLY INGESTED INTO NORTHERN STREAM SUNDAY NIGHT/MONDAY AND LIFTS NORTH OF THE FORECAST AREA AROUND BUILDING MID LEVEL RIDGE AXIS LOCATED ACROSS GREAT LAKES REGION. LARGER SCALE UPPER TROUGH AXIS MOVING ACROSS NORTHERN ROCKIES/NORTHERN PLAINS INDUCES STRONGER LOW LEVEL RETURN FLOW AND FOCUS FOR PRECIPITATION OFF TO OUR WEST ACROSS THE PLAINS MONDAY AND MONDAY NIGHT. SHORT WAVE THEN LIFTS NORTH EAST ACROSS UPPER MIDWEST TUESDAY AS IT BUMPS UP AGAINST GREAT LAKES UPPER RIDGE...WITH WEAKENING LOW LEVEL COLD FRONTAL BOUNDARY MOVING INTO THE WESTERN LAKES TUESDAY NIGHT OR WEDNESDAY. 12Z ECMWF A LITTLE SLOWER THAN THE 12Z GFS WITH FRONT AND ASSOCIATED PRECIP THREAT...WITH SLOWER SOLUTION ALSO FAVORED BY SREF AND CANADIAN GEM AND HAVE FOLLOWED SLOWER TREND IN THIS REGARD. FRONT MOVES IN DURING THE DAY WEDNESDAY...THOUGH AS UPPER WAVE LIFTS WELL NORTH OF FORECAST AREA AND SURFACE HIGH PRESSURE TO THE EAST FRONT MAKES LITTLE PROGRESS ACROSS FORECAST AREA. UPPER FLOW BEHIND THIS WAVE PROGGED TO BECOME MORE ZONAL ACROSS THE NORTHERN TIER STATES WITH ANOTHER SPEED MAX/TROUGH MOVING ACROSS THE NORTHERN ROCKIES BY EARLY THURSDAY WHICH AGAIN INDUCES SOUTHERLY LOW LEVEL FLOW ACROSS PLAINS AND WASHES OUT FRONT OR LIFTS IT NORTH OF FORECAST AREA LATE THURSDAY NIGHT AND FRIDAY. WITH THIS SCENARIO IN MIND WILL CARRY LOW CHANCE POPS MAINLY ACROSS NORTHWEST/WEST PORTIONS OF CWA WEDNESDAY/WEDNESDAY NIGHT...THEN DRY THURSDAY/FRIDAY AS FOCUS FOR PRECIP SHIFTS NORTH OF THE FORECAST AREA AGAIN. SIMILAR TO SYSTEM WEDNESDAY...MAIN SURFACE LOW WELL TO THE NORTH IN CANADA...WITH WEAK COLD FRONT SAGGING INTO FORECAST AREA LATE FRIDAY NIGHT OR SATURDAY. HAVE KEPT POPS JUST NORTH OF FORECAST AREA DURING THE PERIOD WITH RELATIVELY LOW CONFIDENCE IN ACTUAL FRONTAL TIMING BY DAY 7. AS FOR TEMPS...GUIDANCE MAX/MIN TEMP VALUES FAIRLY SIMILAR BETWEEN FWC/MAV/MET IN SHORT TERM AND GENERALLY FOLLOWED. MEX/HPC NUMBERS ACCEPTED IN LONGER RANGE WITH SYSTEMS MAINLY PASSING NORTH OF FORECAST AREA AND SOUTHERLY FLOW MAKING FOR TEMPS ABOVE NORMAL IN EXTENDED FORECAST...UPPER 70S/AROUND 80 FOR THE MOST PART. RATZER && .AVIATION... 18Z TAFS...MAIN CONCERN FOR THE 18Z TAF ISSUANCE WILL CENTER ON WINDS. THE PRESSURE GRADIENT OVER NRN IL/IN REMAINS QUITE WEAK BETWEEN A COLD FRONT APPROACHING FROM THE NORTH AND AN UPPER LEVEL LOW APPROACHING FROM THE SOUTH. WILL START OUT WINDS LGT/VRBL AT ALL SITES...WHICH IS REFLECTIVE OF THE WEAK GRADIENT AND REPRESENTATIVE OF CURRENT METARS. EXPECT A WEAK LAKE BREEZE TO DEVELOP THIS AFTERNOON AS AMPLE SUNSHINE UNDER MOSTLY CLEAR SKIES...JUST FEW CU AND SCT CI...WILL ENHANCE THE DIFFERENTIAL HEATING BETWEEN LAND AND WATER. IT IS STILL QUESTIONABLE WHETHER THE LAKE BREEZE BNDRY WILL PENETRATE INLAND FAR ENOUGH TO MOVE THROUGH MDW/ORD...SO WILL KEEP THEM SELY THROUGH THE LATE AFTERNOON HOURS. EXPECT ANY LAKE BREEZE TO DISSIPATE AT SUNSET...AND WINDS WILL RETURN TO REFLECTIVE OF THE SYNOPTIC FLOW...WHICH SHOULD BE MORE SWLY. THE NEXT CONCERN WILL BE THE COLD FRONT APPROACHING FROM THE NORTH. BASED ON THE LATEST GUIDANCE...EXPECT THE FRONT TO PUSH INTO NRN IL SHORTLY AFTER MIDNIGHT...SO WILL DELAY THE WIND SHIFT TO NELY UNTIL 08Z. HAVE MAINTAINED THE POSSIBILITY OF BR FORMATION FOR THE EARLY MORNING HOURS. GIVEN THAT THE AIRMASS TRANSFORMATION WITH THE FROPA WILL BE SLOW...EXPECT THAT THE COOLING ASSOCIATED WITH THE FROPA AND THE MOISTURE LEVELS CURRENTLY IN PLACE WILL LEAD TO MORE WIDESPREAD BR DEVELOPMENT THAN WAS OBSERVED THIS MORNING. GIVEN THE EARLY MORNING TIMING OF FROPA...FEEL THAT THERE IS LITTLE CHANCE FOR ANY PCPN ASSOCIATED WITH THE FRONT. THERE MAY BE SOME CONCERN WITH SOME SHRA DEVELOPING TOWARD THE END OF THE PERIOD ASSOCIATED WITH THE UPPER LEVEL LOW APPROACHING FROM THE SOUTH. CURRENT INDICATIONS LOOK LIKE ANY PCPN ASSD WITH THIS SYSTEM WILL REMAIN SOUTH AND WEST OF THE TERMINALS...BUT THIS WILL NEED TO BE MONITORED FOR LATER UPDATES. KREIN && .MARINE... 230 PM...A COLD FRONT PUSHING SOUTH DOWN THE LENGTH OF LAKE MICHIGAN WILL REACH THE SOUTH TIP OF THE LAKE LATE TONIGHT. IN THE WAKE OF THE FRONTAL PASSAGE...WINDS WILL TURN NLY-NELY AN INCREASE TO 15-25KT. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT...OVER THE NORTHERN GREAT LAKES TONIGHT AND SUNDAY. THE HIGH WILL SPREAD EAST OVER SOUTHERN QUEBEC AND THE EASTERN LAKES SUNDAY NIGHT AS A TROUGH OF LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS. THIS TROUGH WILL SLOWLY MOVE EAST ACROSS THE PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY WEDNESDAY MORNING. && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 239 PM CDT SAT SEP 20 2008 .DISCUSSION... 1221 PM CDT BRIEF AFTERNOON UPDATE TO FORECAST GRIDS/ZFP. LOCAL RADAR DEPICTS SHOWERS AND ISOLATED THUNDERSTORMS DEVELOPING ACROSS CENTRAL ILLINOIS EARLY THIS AFTERNOON...ON NORTHERN PERIPHERY OF CUT OFF UPPER LOW ACROSS SOUTHERN IL. RUC/SPC MESOANALYSIS PRODUCTS INDICATE AIRMASS HAS BECOME WEAKLY UNSTABLE WITH MLCAPES 500-1000 J/KG WITH LITTLE/NO CIN. SOME CU CONGESTUS/TCU TRYING TO FORM OUT THE WFO WINDOW...THOUGH CURRENTLY APPEARS AREA MOST LIKELY TO SEE SCATTERED RW/TRW WILL BE FAR SOUTH COUNTIES ALONG ILX CWA BORDER...WHERE WEAK LOW LEVEL CONVERGENCE IS A LITTLE MORE PRONOUNCED THAN IN THE LIGHT/VARIABLE WIND FIELD FARTHER NORTH. OTHERWISE LITTLE CHANGE TO GOING FORECAST FOR REMAINDER OF AFTERNOON HOURS. RATZER && .AVIATION... 18Z TAFS...MAIN CONCERN FOR THE 18Z TAF ISSUANCE WILL CENTER ON WINDS. THE PRESSURE GRADIENT OVER NRN IL/IN REMAINS QUITE WEAK BETWEEN A COLD FRONT APPROACHING FROM THE NORTH AND AN UPPER LEVEL LOW APPROACHING FROM THE SOUTH. WILL START OUT WINDS LGT/VRBL AT ALL SITES...WHICH IS REFLECTIVE OF THE WEAK GRADIENT AND REPRESENTATIVE OF CURRENT METARS. EXPECT A WEAK LAKE BREEZE TO DEVELOP THIS AFTERNOON AS AMPLE SUNSHINE UNDER MOSTLY CLEAR SKIES...JUST FEW CU AND SCT CI...WILL ENHANCE THE DIFFERENTIAL HEATING BETWEEN LAND AND WATER. IT IS STILL QUESTIONABLE WHETHER THE LAKE BREEZE BNDRY WILL PENETRATE INLAND FAR ENOUGH TO MOVE THROUGH MDW/ORD...SO WILL KEEP THEM SELY THROUGH THE LATE AFTERNOON HOURS. EXPECT ANY LAKE BREEZE TO DISSIPATE AT SUNSET...AND WINDS WILL RETURN TO REFLECTIVE OF THE SYNOPTIC FLOW...WHICH SHOULD BE MORE SWLY. THE NEXT CONCERN WILL BE THE COLD FRONT APPROACHING FROM THE NORTH. BASED ON THE LATEST GUIDANCE...EXPECT THE FRONT TO PUSH INTO NRN IL SHORTLY AFTER MIDNIGHT...SO WILL DELAY THE WIND SHIFT TO NELY UNTIL 08Z. HAVE MAINTAINED THE POSSIBILITY OF BR FORMATION FOR THE EARLY MORNING HOURS. GIVEN THAT THE AIRMASS TRANSFORMATION WITH THE FROPA WILL BE SLOW...EXPECT THAT THE COOLING ASSOCIATED WITH THE FROPA AND THE MOISTURE LEVELS CURRENTLY IN PLACE WILL LEAD TO MORE WIDESPREAD BR DEVELOPMENT THAN WAS OBSERVED THIS MORNING. GIVEN THE EARLY MORNING TIMING OF FROPA...FEEL THAT THERE IS LITTLE CHANCE FOR ANY PCPN ASSOCIATED WITH THE FRONT. THERE MAY BE SOME CONCERN WITH SOME SHRA DEVELOPING TOWARD THE END OF THE PERIOD ASSOCIATED WITH THE UPPER LEVEL LOW APPROACHING FROM THE SOUTH. CURRENT INDICATIONS LOOK LIKE ANY PCPN ASSD WITH THIS SYSTEM WILL REMAIN SOUTH AND WEST OF THE TERMINALS...BUT THIS WILL NEED TO BE MONITORED FOR LATER UPDATES. KREIN && .MARINE... 230 PM...A COLD FRONT PUSHING SOUTH DOWN THE LENGTH OF LAKE MICHIGAN WILL REACH THE SOUTH TIP OF THE LAKE LATE TONIGHT. IN THE WAKE OF THE FRONTAL PASSAGE...WINDS WILL TURN NLY-NELY AN INCREASE TO 15-25KT. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT...OVER THE NORTHERN GREAT LAKES TONIGHT AND SUNDAY. THE HIGH WILL SPREAD EAST OVER SOUTHERN QUEBEC AND THE EASTERN LAKES SUNDAY NIGHT AS A TROUGH OF LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS. THIS TROUGH WILL SLOWLY MOVE EAST ACROSS THE PLAINS...REACHING THE UPPER MISSISSIPPI VALLEY BY WEDNESDAY MORNING. && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...NONE. && $$ il AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE GOODLAND KS 226 PM MDT SAT SEP 20 2008 .DISCUSSION... 221 PM MDT SAT SEP 20 2008 16Z WATER VAPOR IMAGERY/RUC ANALYSIS INDICATED STRONG SHORT WAVE TROUGH MOVING ACROSS NORTHERN NEVADA WITH RIDGE ACROSS CENTRAL CONUS. AT THE SFC...TROUGH WAS LOCATED ACROSS EASTERN COLORADO...ALTHOUGH PRESSURE FALL ANALYSIS THROUGH THE MORNING HAD INDICATED VERY LITTLE DEVELOPMENT WITH IT. FAIRLY STEEP LAPSE RATES WERE APPARENT ON KDDC AND ESPECIALLY KLBF BETWEEN H85 AND H7. MOISTURE PROFILES APPEAR LACKING AT THE MOMENT...ALTHOUGH DEEPER MOISTURE WAS OBSERVED DOWNSTREAM AT KOUN. SHORT RANGE MODELS IN GENERAL AGREEMENT WITH LARGE SCALE FEATURES IN THE BEGINNING OF THE FORECAST...BUT BY 60HRS GFS APPEARS TO BE ALONG IN ITS DEEPER FASTER H5 TROUGH SOLUTION AND WILL LEAN MORE TOWARDS NAM/CANADIAN SOLUTION FOR LATER PERIODS. TONIGHT...WITH OBSERVED STEEP LAPSE RATES ALREADY IN PLACE...SHOULD BE A FAIRLY DECENT RESPONSE TO WAA THAT WILL DEVELOP OVER THE AREA TONIGHT AS RIDGE AXIS SHIFTS TO THE EAST. 40KT LLJ WILL DEVELOP OVERNIGHT AS JET STREAK APPROACHES...BUT FORCING ALONG THIS FEATURE APPEARS WEAK AT THE MOMENT AND CENTERED TO THE EAST OF THE AREA. ALTHOUGH DOWNSTREAM RAOBS APPEAR LACKING IN MOISTURE THIS MORNING...WV IMAGERY SUGGESTS A PLUME OF PAC MOISTURE ALREADY ADVECTING TO THE SOUTHEAST SECTION OF APPROACHING TROUGH...AND LLJ WILL ALSO AID IN MOISTURE TRANSPORT. PICKING A LOCATION OF BEST FORCING A BIT DIFFICULT AS BEST H85 LLJ CONVERGENCE ACROSS EXTREME EASTERN CWA...BUT STRONGEST H7-H6 WAA ACROSS THE WEST AND CENTRAL. THERE DOES EXIST A FRONTOGENESIS MAX ALONG THERMAL RIDGE OVERNIGHT...BUT SINCE THERMAL RIDGE IS TO THE WEST...BEST FORCING WILL ALSO BE ON THE WEST SIDE OF THIS AXIS. WITH FORCING APPARENTLY CENTERED MORE OVER THE WEST THAN EAST...WILL MOVE POPS WESTWARD BUT WILL NOT LOWER THEM MUCH ACROSS THE EAST DUE TO LLJ FORCING. CONSIDERED UPPING POPS SOME...BUT INSTABILITY WILL RELY ON PARCELS BECOMING SATURATED AND LARGE CONDENSATION PRESSURE DEFICITS ON 310K SURFACE DOES NOT BRING A LOT OF CONFIDENCE THAT THIS WILL OCCUR. TOMORROW-TOMORROW NIGHT...AREA OF WAA/ISENTROPIC UPGLIDE WILL SHIFT TO THE EAST WITH RIDGE AXIS DURING THE THE DAY AND EXPECT ANY ONGOING PRECIPITATION TO END DURING THE MORNING. SOUTHWESTERLY FLOW ALOFT WILL MOVE IN ACROSS THE AREA BEHIND THE DEPARTING RIDGE. ALTHOUGH SYNOPTIC SCALE FORCING DOES NOT LOOK PARTICULARLY STRONG DURING THE AFTERNOON. LEE TROUGH/DEVELOPING SFC LOW LINES UP WELL WITH NARROW AXIS OF INSTABILITY ACROSS THE WEST...AND EXPECT THIS TO BE AREA WHERE STORMS DEVELOP TOMORROW AFTERNOON/EVENING. DIV Q FIELDS INDICATE ANOTHER WEAK TROUGH MOVING ACROSS THE REGION OVERNIGHT. IN ADDITION ANOTHER...STRONGER...LLJ DEVELOPS ACROSS THE AREA OVERNIGHT WITH BEST CONVERGENCE ACROSS THE NORTH AND EAST WHICH SHOULD ALLOW STORMS TO MAINTAIN THEMSELVES THROUGH THE NIGHT. OTHER CONCERN WILL BE WINDS AS SFC LOW DEVELOPS ACROSS EASTERN COLORADO AND LIFTS TO THE NORTHEAST. MODELS DISAGREE ON PLACEMENT OF STRONGEST WINDS...BUT ALL TEND TO AGREE SUSTAINED WINDS IN THE 25-30KT RANGE FOR PORTIONS OF THE AREA. PEAK WINDS IN THE MIXED COLUMN REMAIN IN THE 30-35KT THROUGH THE EARLY AFTERNOON BUT BEGIN TO PICK UP AROUND 00Z WITH PEAK WINDS IN THE MIXED LAYER APPROACHING 40 KTS. OVERALL PATTERN SEEMS FAVORABLE FOR WIND ADVISORY CONDITIONS WITH LOW DEEPENING TO THE WEST...BUT LARGE DIFFERENCES IN PLACEMENT OF STRONGER WINDS AND SOME DISCREPANCIES IN OVERALL MAGNITUDE OF THE WIND SPEEDS LOWER CONFIDENCE IN ISSUING AN ADVISORY AT THIS POINT. WITH IT APPEARING MORE LIKELY TO BE A SUSTAINED WIND EVENT AND GUSTS...GENERALLY ONLY BARLEY MEETING CRITERIA...THINK I WILL HOLD OF ANY HIGHLIGHTS FOR NOW. MONDAY-TUESDAY...SOUTHWEST FLOW ALOFT WILL CONTINUE ACROSS THE AREA WILL PREVAIL ACROSS THE AREA ON MONDAY AND TUESDAY. STRONG SHORTWAVE TROUGH WILL SWEEP ACROSS THE NORTHERN PLAINS ON MONDAY NIGHT...FORCING A COLD FRONT ACROSS THE AREA. MOISTURE AND INSTABILITY DUE APPEAR LIMITED DURING THE DAY...BUT BOTH NAM AND GFS INDICATE CINH NEARLY REMOVED BY THE AFTERNOON AND FORCING ALONG DRYLINE SHOULD BE ENOUGH TO DEVELOP A STORM OR TWO. FRONT WILL MOVE THROUGH THE AREA MONDAY EVENING AND WITH FAVORABLE LOCATION OF H3 JET NEARBY WILL KEEP CURRENT FORECAST FOR POPS/WX OVERNIGHT. SREF HANGS ONTO FRONT ACROSS EASTERN CWA DURING TUESDAY AFTERNOON AND WILL INCLUDE LOW POPS ALONG FRONTAL ZONE. FIRE WX CONCERNS MAY ALSO ONCE AGAIN RETURN TO THE AREA ON MONDAY AFTERNOON BEHIND THE DRYLINE. RH`S STAY JUST ABOVE CRITICAL VALUES (16-20%) RANGE DURING THE AFTERNOON WITH SOME INDICATIONS THAT WINDS MAY GUST TO AROUND CRITICAL VALUES. RIGHT NOW...DOES NOT LOOK LIKE CRITERIA WILL BE MET BUT WILL HAVE TO CONTINUE TO WATCH IT. IN THE EXTENDED...MEDIUM RANGE MODELS IN GENERAL AGREEMENT THROUGH THE PERIOD WITH RIDGE AMPLIFYING ACROSS THE REGION BEHIND DEPARTING H5 TROUGH ON WEDNESDAY. SOME DIFFERENCES ARE APPARENT IN OPERATIONAL RUNS...WITH 06Z GFS AND 00Z ECMWF SHOWING REASONABLE AGREEMENT THROUGH MUCH OF THE PERIOD. 00Z GFS ENS MEAN ACTUALLY SUPPORTS ECWMF SOLUTION TOWARDS THE LATTER PERIODS AND WILL WEIGHT FORECAST IN THIS DIRECTION. MUCH OF THE FORECAST LOOKS DRY...WITH POSSIBLE EXCEPTION OF OVERNIGHT WEDNESDAY. GFS INDICATING SOME ELEVATED INSTABILITY ON NOSE OF 310K PRESSURE ADVECTION...WITH A COHERENT TONGUE OF MOISTURE FEEDING INTO THE AREA. OTHER MODELS DO NOT APPEAR TO BE SUPPORTING THIS AND NOT READY TO GO ANY HIGHER THAN A 20 POP FOR THIS PERIOD. TEMPERATURES WILL BE OTHER CONCERN AS MODELS GENERALLY AGREE IN WARMING H85 TEMPS INTO THE MID 20S BY NEXT WEEKEND. WARMED TEMPS UP SEVERAL DEGREES...BUT WITH CWA JUST ON THE FRINGE OF H5 RIDGE...WORRIED THAT A FRONT OR TWO MAY MAKE ITS WAY INTO THE CWA DURING THE PERIOD AND DID NOT WANT TO GO OVERBOARD WITH THE WARMING AT THIS POINT. JRM && .AVIATION... 1140 AM MDT SAT SEP 20 2008 FOR THE 12Z TAFS... VFR CONDITIONS SHOULD PREVAIL THROUGH THIS ENTIRE FORECAST. INITIALLY VERY FEW CLOUDS WILL BE PRESENT THROUGH THE AFTERNOON AND EVENING. MID/HIGH LEVEL CLOUDS WILL INCREASE AS THE UPPER LEVEL TROUGH MOVES ACROSS THE AREA AFTER 06Z SUNDAY. ISOLATED THUNDERSTORMS WILL BE POSSIBLE SOUTHEAST OF KMCK BUT SHOULD NOT IMPACT THE AIRPORT. FORECAST SOUNDINGS INDICATE THAT MID LEVEL CLOUDS WILL PERSIST AT BOTH SITES THROUGH 18Z SUNDAY. FS && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 258 PM EDT SAT SEP 20 2008 .SHORT TERM.../TONIGHT THROUGH SUNDAY/...UPDATED MOST INSTABILITY IN RUC/NAM CURRENTLY IS WHERE THE FEW SHOWERS ARE DEVELOPING IN AND BORDERING THE BLUEGRASS AREA. BUT LIMITED CAPE AND A SIGNIFICANT CAP IS TRYING TO SUPPRESS THE SHOWERS AND EXPECT THAT SUNSET APPROACHING IN A FEW HOURS WILL ALLOW THESE SHOWERS TO DIE BEFORE DARK. WILLIAMSBURG AND SOMERSET MAY SOON ALSO FIRE SOME SINCE THEY ARE APPROACHING CONVECTIVE TEMPERATURES WITH THE WEAK SHORTWAVE IN THE AREA. THE SHORTWAVE CONTINUES TO WEAKEN TONIGHT AND SUNDAY WHILE ADVECTING MOISTURE MAINLY TOWARD THE NORTHWEST RATHER THAT INTO EAST KENTUCKY. .LONG TERM.../SUNDAY NIGHT THROUGH SATURDAY/...UPDATED THE LONG TERM MODELS ARE STILL NOT SHOWING ANY INDICATION OF WHEN THE BLOCKING RIDGE IS GOING TO BREAK DOWN. AS SUCH...WILL KEEP EVERYTHING DRY THROUGH THE ENTIRE PERIOD. THE PATTERN OF WARM TO HOT AFTERNOONS AND COOL MORNINGS WILL CONTINUE. ONLY MADE MINOR TWEAKS TO THE PREVIOUS FORECAST TO REFLECT MOS TRENDS. && .AVIATION.../18Z TO 18Z/ VFR AND LIGHT WINDS WILL CONTINUE THROUGH THE PERIOD EXCEPT FOR A BIT OF FOG SUNDAY MORNING. SME/LOZ MIGHT HAVE LIMITED VISIBILITY REDUCTIONS. THOUGH ISOLATED SHOWERS COULD DEVELOP LATE THIS AFTERNOON FROM WILLIAMSBURG TO FLEMINGSBURG BELIEVE THE CHANCES ARE SLIM ENOUGH TO LEAVE THEM OUT OF TAFS FOR SME/LOZ. WILL KEEP AN EYE ON THAT POSSIBILITY FOR ANY UPDATE. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...GV LONG TERM...JJ AVIATION...GV ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 156 PM EDT SAT SEP 20 2008 .SHORT TERM.../THE REST OF TODAY/ CHANCE OF SHOWERS TODAY RESTS ON HOW STRONG IS THE CAP BETWEEN 650 AND 750 MB. 12Z RUC/06Z NAM WOULD SUGGEST THAT ENOUGH INSTABILITY IS PRESENT ALONG WITH THE APPROACHING VERY WEAK SHORTWAVE ASSOCIATED WITH SOME SHOWERS CURRENTLY IN MIDDLE TN FOR AT LEAST ISOLATED OR SCATTERED SHOWERS AND EVEN THUNDER. THIS CAP IN THE 12Z NAM IS SLIGHTLY STRONGER THAN THE 06Z RUN BUT WITH ENOUGH MOISTURE TO OVERCOME IT FOR POSSIBLE AFTERNOON CONVECTION. 06Z GFS SHOWS A MORE ROBUST CAP AND LESS MOISTURE WHILE 12Z BNA SOUNDING SHOWED MORE AND DEEPER MOISTURE THAN THIS MODEL INDICATED. GIVEN THAT WE SHOW A CHANCE OF SHOWERS FOR OUR WEST PORTION WHILE NEARBY LOCATIONS DO NOT INDICATE THAT MUCH CHANCE CANNOT JUSTIFY INCREASING POPS...BUT WILL MONITOR FOR UPDATE. CONVECTIVE TEMPERATURES ARE GENERALLY IN THE MID/UPPER 70S SO LOWERED MAX TEMPERATURES 2-3 DEGREES. SHOULD HAVE AN EARLIER START TO CONVECTIVE CLOUDS ALONG WITH CONVECTIVE DEBRIS FROM DECAYING SHOWERS FROM TN TO KEEP TEMPERATURES DOWN SLIGHTLY FROM YESTERDAYS VALUES. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TODAY THROUGH MONDAY/ EARLY THIS MORNING...SUBTROPICAL RIDGE EXTENDS FROM THE GULF OF MEXICO EAST INTO THE WESTERN ATLANTIC. WELL TO THE NORTH...RATHER FAST WESTERLIES WERE GENERALLY NORTH OF THE US CANADIAN BORDER WITH A TROUGH MOVING THROUGH THE JAMES BAY/HUDSON BAY REGION DOWN INTO ONTARIO AND QUEBEC. AN UPPER LEVEL LOW WAS OVER THE MID MS VALLEY...NEAR THE CONFLUENCE OF THE OH AND MS RIVERS. AT THE SFC...AN EXPANSIVE RIDGE OF HIGH PRESSURE EXTENDS SOUTH INTO THE APPALACHIANS FROM THE NORTHEASTERN UNITED STATES. THROUGH SUNDAY...THE WEAK CLOSED LOW IS FORECAST BY THE MODELS TO REMAIN NEARLY STATIONARY TO THE WEST OF THE AREA LARGELY AND THEN DAMPEN OUT TO END THE PERIOD. IN FACT...THIS WILL LEAD TO RISING HEIGHTS AT THE END OF THE PERIOD...AND BOTH THE GFS AND NAM INDICATE SW/V UPPER RIDGING WORKING BACK ACROSS THE AREA ON MONDAY. A WEAK BOUNDARY WILL DISSIPATE AS IT MOVES SOUTH OF THE GREAT LAKES ON SUN NIGHT INTO MONDAY...AS THE NEXT REINFORCING AREA OF HIGH PRESSURE WORKS INTO EASTERN/CANADA AND THE NORTHEASTERN UNITED STATES IN CONCERT WITH THE RISING HEIGHTS OVER THE GREAT LAKES AND OH VALLEY. REGIONAL SFC OBSERVATIONS REVEAL HIGHER DEWPOINTS CURRENTLY NEAR AND WEST OF THE INTERSTATE 75 CORRIDOR...OR GENERALLY CLOSER TO THE UPPER LEVEL SYSTEM. LOW LEVEL FLOW FURTHER EAST IS SOUTHEAST OR DOWNSLOPE... THOUGH RECENT VWP INDICATES IT IS BECOMING MORE SOUTHERLY. THE FINER RESOLUTION NAM AS WELL AS THE 21Z SREF GENERALLY INDICATE THAT THE DOWNSLOPE FLOW WILL WEAKEN WITH MORE SOUTHERLY TO WEAK WESTERLY FLOW OVER THE WESTERN AREAS...ALLOWING FOR LIMITED MOISTURE ADVECTION. THEN NAM AND SREF DEVELOP A WEAK TROUGH OF LOW PRESSURE/AREA OF CONVERGENCE NEAR THE OH RIVER AND EXTENDING EAST IN THE BLUEGRASS REGION. WITH BETTER MOISTURE IN PLACE AND EXPECTED TO REMAIN BETTER OVER THE WESTERN COUNTIES...A FEW SHOWERS CANNOT BE RULED OUT THIS AFTERNOON OVER THIS REGION AS CAPPING WILL BE WEAKER THERE CLOSER TO THE CLOSED LOW THAN IN AREAS FURTHER TO THE EAST. AREAS IN OR NEAR WHERE SHOWERS OCCURRED ON FRI EVENING CANNOT BE RULED OUT FOR POSSIBLE VERY ISOLATED SHOWERS ON SAT DUE TO DIFFERENTIAL HEATING BOUNDARIES...BUT KEPT THESE AREAS OF FAR SE KY DRY FOR NOW AS THEY APPEAR TO BE CAPPED. THE CHANCE FOR SHOWERS WILL WANE WITH THE LOSS OF DAYTIME HEATING...BUT THE CAP AGAIN APPEARS AS IF IT WILL BE WEAKER ON SUN OVER THE FAR SW COUNTIES NEAR LAKE CUMBERLAND AND AGAIN INCLUDED A SLIGHT CHANCE POP FOR THESE AREAS. THE REMAINDER OF THE PERIOD WILL BE DRY AS HEIGHTS RISE. ANY MOISTURE FROM THE DYING BOUNDARY ON MON SHOULD ONLY LEAD TO AN INCREASE IN SHALLOW AFTERNOON CU OVER NE KY. AS FOR TEMPERATURES...THE ONGOING DROUGHT CONTINUES TO HAVE AN EFFECT AND LOZ AND JKL AGAIN VERIFIED WARMER THAN MOS GUIDANCE FOR FRI MAX T AND EXPECT THIS TO CONTINUE FOR MAX T THROUGH THE SHORT TERM AT BOTH SITES. GUIDANCE AT SME WAS GENERALLY FOLLOWED...THOUGH WITH THE RIDGE BUILDING IN ON MON...THE WARMER MAV MAX TEMP APPEARED IN ORDER. OTHERWISE...RIDGE/VALLEY TEMP SPLITS AS WELL AS PATCHY FOG BETWEEN 6Z AND 13Z EACH NIGHT AND EARLY EACH MORNING WILL CONTINUE. MAV GUIDANCE AND NAM DATA BOTH INDICATE FALLING DEWPOINTS ON SUN AS NE FLOW USHERS IN SOME DRIER AIR. THIS WILL LIKELY LEAD TO THE COOLEST VALLEY READINGS DURING THE PERIOD ON MON AM...WHERE THE NORMALLY COLD SPOTS SHOULD FALL INTO THE UPPER 40S. .LONG TERM.../MONDAY NIGHT THROUGH FRIDAY/ FOR THE EXTENDED...THE LONGWAVE PATTERN HOLDS LITTLE HOPE FOR PCPN MAKING INTO EAST KENTUCKY AS THE RIDGE...MENTIONED ABOVE...TILTS NORTHEASTWARD WHILE THE WESTERN TROUGH PLOWS ACROSS SOUTHERN CANADA AND THE NORTHERN PLAINS. AS THE UPPER PATTERN THUS FLATTENS OUT... RIDGING WILL HOLD ON STRONG OVER THE SOUTHERN 2/3RDS THE NATION WHILE THE WESTERLIES RACE BY WELL TO THE NORTH. THE ECMWF FROM 00Z/19 WAS FOLLOWED CLOSEST GIVEN ITS RECENT PERFORMANCE AND REASONABLE SOLUTION. ONE INTERESTING ASPECT OF IT/S SOLUTION...THOUGH ONE NOT SO MUCH RESOLVED IN THE GFS...WAS THE DEVELOPMENT OF AN UPPER LOW OFF THE SOUTHEAST COAST FROM MIDWEEK ON. THIS APPEARS TO FURTHER AMPLIFY THE RIDGE TO ITS WEST...HAMMERING HOME THE IDEA OF A DRY EXTENDED FOR OUR AREA. A QUICK PEEK AT THE 12Z ECMWF SEES IT CONTINUING THIS TREND. FOR SENSIBLE WEATHER...IT IS AS IF THE WEATHER PATTERN IS COMING UP WITH NEW WAYS TO KEEP EAST KENTUCKY DRY. RIDGING ALOFT WILL MAKE ANY FRONT THAT MANAGES TO COME THROUGH HERE A DRY PASSAGE...AN UPPER LOW...AND ITS WEAK SFC REFLECTION...TO THE WEST WILL FALL APART BEFORE GETTING CLOSE ENOUGH TO GIVE US RAIN...AND FINALLY A POTENTIAL EAST COAST SYSTEM LATE IN THE PERIOD WILL ONLY SERVE TO KEEP OUR AREA IN SUBSIDENCE WHILE STRENGTHENING THE UPPER RIDGING JUST OFF TO OUR WEST. IN THIS REGIME...AM LOATH TO FORECAST ANY PCPN. AS A RESULT...A PERSISTENCE FORECAST WAS CARRIED THROUGH FRIDAY WITH ADJUSTMENTS MADE FOR THE VAGARIES OF DRY FRONTS AND VARIOUS HIGH PRESSURE SYSTEMS PASSING THROUGH. THE ONLY HOPE I SEE FOR MUCH NEEDED RAIN IS THE SEASONAL EXPECTATION OF THE WESTERLIES EVENTUALLY PUSHING FAR ENOUGH SOUTH TO AFFECT US...BEYOND THE EXTENDED. UNTIL THAT HAPPENS THOUGH...DRY AND SEASONALLY WARM TEMPERATURES WILL CONTINUE TO DOMINATE THE FORECAST. && .AVIATION.../18Z TO 18Z/...UPDATED VFR AND LIGHT WINDS WILL CONTINUE THROUGH THE PERIOD EXCEPT FOR A BIT OF FOG SUNDAY MORNING. SME/LOZ MIGHT HAVE LIMITED VISIBILITY REDUCTIONS. THOUGH ISOLATED SHOWERS COULD DEVELOP LATE THIS AFTERNOON FROM WILLIAMSBURG TO FLEMINGSBURG BELIEVE THE CHANCES ARE SLIM ENOUGH TO LEAVE THEM OUT OF TAFS FOR SME/LOZ. WILL KEEP AN EYE ON THAT POSSIBILITY FOR ANY UPDATE. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...JP/GV LONG TERM....GREIF AVIATION...GV ky AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PADUCAH KY 1215 PM CDT SAT SEP 20 2008 .UPDATE... ADJUSTMENTS FOR FIRST PERIOD /THIS AFTERNOON/ SENSIBLE WEATHER TRENDS AND 18Z SATURDAY ROUTINE TAF ISSUANCE. && .DISCUSSION... MAIN CIRCULATION CENTER WITH CLOSED LOW CENTERED NORTH OF ST. LOUIS AROUND NOON TODAY. MOST OF THE NUMERICAL GUIDANCE FROM MEDIUM TO SHORT RANGE HAVE INITIALIZED OR PROGGED THE MID LEVEL /500 MB/ CIRCULATION TOO FAR SOUTH OR EAST THAN THE 12Z UPPER AIR ANALYSIS OF THE SYSTEM. IN GENERAL TERMS...THE 00Z ECMWF AND 06Z GFS DID NOT DO TOO POORLY...BUT UNDERESTIMATED THE HEIGHT OF THE LOW BY 10-30 DM. FOR THE MORNING UPDATE...RELIED AND PLACED MORE WEIGHT ON THE 13KM RUC AND 40KM GFS GUIDANCE. THE END RESULT IS MORE CLOUDS DURING THE MID-AFTERNOON...LOWER MAXIMUM TEMPERATURES BY ONE CATEGORY. INSTABILITY WILL REMAIN MARGINAL THROUGH AT LEAST 19Z...SO LEANED HEAVILY TOWARD SHOWER ONLY WORDING THROUGH NOON. DURING THE AFTERNOON...WHERE DIFFERENTIAL HEATING WILL BE STRONGEST ALONG THE EDGE OF THE UPPER CIRCULATION...A LOWER...BUT EQUAL CHANCE FOR THUNDERSTORMS WILL BE POSSIBLE. FOR THIS REASON...I DECIDED TO USE EQUIVALENT PROBABILITIES FOR SHOWER VS. THUNDERSTORMS THIS AFTERNOON. && .AVIATION... IN THE MAIN ZONE OF CONVECTIVE ACTIVITY THIS AFTERNOON...KCGI/KPAH...WILL KEEP MVFR CEILINGS IN PLACE FOR AT LEAST THE FIRST 6-12 HOURS OF THE FORECAST...WITH VFR CONDITIONS IN PLACE FOR KEVV/KOWB. IT WILL BE SOMEWHAT DIFFICULT TO PIN DOWN THE LIKELIHOOD FOR VICINITY THUNDERSTORMS IN EACH OF THE TAF SITES THROUGH THE REMAINDER OF THE FORECAST...AS THE UPPER LOW WILL CONTINUE TO WOBBLE CLOSE TO THE WFO PAH FORECAST AREA. WITH THIS PARTICULAR FORECAST ISSUANCE...I HAVE LOW CONFIDENCE ON PINPOINTING CONVECTIVE ACTIVITY AND THE OCCURRENCE OF MVFR CEILINGS AND VISIBILITIES...ESPECIALLY NEAR THE KEVV/KOWB TAF SITES. CLOSER TO THE UPPER LOW...I EXPECT A GREATER PROBABILITY OF SHOWERS/MVFR CEILINGS AT KCGI/KPAH. && .DISCUSSION... /ISSUED 648 AM CDT SAT SEP 20 2008/ DISCUSSION... THE WETTER NAM MODEL HAS PROVED TO BE THE BETTER NEAR TERM PREDICTOR OF ONGOING PCPN...AT LEAST JUDGING BY FRIDAY THRU THE CURRENT TIME RADAR SNAPS. NAM SHOWS UPPER LOW CONTINUING TO CIRCULATE ACROSS PAH FA THRU SUNDAY...KEEPING ITS FEED OF 60S TDS ACROSS THE MID MS VALLEY. THE BEST SUCH POPS WILL BE CLOSER TO THE CENTER OF THE LOW CIRCULATION...MAINLY NORTH/WEST PORTIONS OF THE FA...TAPERING TO THE LEAST POPS EAST. BY SUNDAY NIGHT...HEIGHTS START TO REBOUND...AND AS A RESULT THE LOW`S CIRCULATION FIZZLES OUT AND THE MOISTURE FEED IS CUT OFF. THE DEVELOPING HIGH TO OUR NORTH AND EAST ENDS UP DRAGGING IN DRIER AIR FROM THE EAST AND POURING IT INTO OUR ATMOS COLUMN BY TUESDAY AS A DOWNSTREAM ANTI-CYCLONIC SURFACE CIRCULATION IS REFLECTED UNDERNEATH THE UPPER RIDGE. THIS CONFIRMS THE REMAINDER OF THE FORECAST LOOKING DRY EXCEPT MAYBE A WEAK SYSTEM APPROACHING FROM THE WEST BY LATE IN THE WEEK...TO BE CONSIDERED IN FUTURE RUNS. NAM PREF LEADS TO MET MOS FAVOR W/THE USUAL COLLAB BLEND...RESULTING IN A SLIGHTLY MORE HUMID NEAR TERM...AT LEAST TIL THE LOW FIZZLES. AVIATION... BEST CHANCES FOR SHOWERS AND THUNDERSTORMS TODAY WILL BE ALONG AND WEST OF THE MISSISSIPPI RIVER...AND OVER SOUTHWEST ILLINOIS. SHOWERS AND THUNDERSTORMS LOOK LIKE A CERTAINTY AT TIMES AT KCGI...WITH LESSER CHANCES AT KPAH. MVFR CIGS AND VSBYS ARE POSSIBLE IN AREAS WITH SHOWERS AND STORMS. KEVV AND KOWB SHOULD CONTINUE WITH VFR CONDITIONS FOR MOST OF THE TAF PERIOD. THOUGH SHOWER AND THUNDERSTORM CHANCES WILL DECREASE AFTER 00Z...BEST CHANCES WILL REMAIN ALONG AND WEST OF THE MISSISSIPPI RIVER. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ SHORT TERM...SMITH LONG TERM....CN AVIATION...SMITH ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 209 PM EDT SAT SEP 20 2008 .SYNOPSIS... HIGH PRESSURE WILL PERSIST OVER THE REGION THROUGH THE WEEKEND... RESULTING IN COOL AND DRY CONDITIONS. HIGH TEMPERATURES WILL BE WARMER MONDAY. THE NEXT...SMALL CHANCE OF SHOWERS DOES NOT ARRIVE UNTIL LATE IN THE WORK WEEK. && .NEAR TERM /THROUGH SUNDAY/... AS OF 205 PM SATURDAY... IT WILL CONTINUE TO BE A DIFFICULT CLOUD FORECAST OVERNIGHT...BASED ON SUBTLE DIFFERENCES BETWEEN THE NAM AND GFS IN THE UPPER-LEVEL MOISTURE FORECAST...AND WHAT WILL EVENTUALLY TRANSPIRE IN THE LOW LEVELS. FAIRLY EXPANSIVE STRATOCU FIELD EXISTS OVER CENTRAL AND EASTERN ZONES THOUGH WITH ENOUGH BREAKS THAT TEMPERATURES HAVE ESSENTIALLY RISEN TO NEAR FORECAST HIGHS. THE NAM...IN ITS LOW- LEVEL RELATIVE HUMIDITY FIELDS AND ON ITS BUFR SOUNDINGS...SUGGESTS LOW-LEVEL CLOUDS WILL BE SLOW TO ERODE THIS EVENING...BUT EVENTUALLY BECOMING MORE SCATTERED AS 300-310K ISENTROPIC LIFT DIMINISHES AND ACTUALLY TRANSITIONS MORE TO ISENTROPIC DESCENT DURING THE ESPECIALLY NORTH WITH AN ASSOCIATED DECREASE IN 850MB THETA-E. THE GFS AND RUC ARE FASTER WITH CLOUD EROSION...PROVIDING FOR DECENT DRYING IN THE 925MB LAYER BY 03Z. AVAILABLE LOW-LEVEL MOISTURE AND PERSISTENT NORTHEAST FLOW...ALONG WITH SATELLITE TRENDS...WOULD TEND TO SUPPORT THE NAM...AND OVERALL ANTICIPATE AREAS OF STRATOCU TO BECOME MORE SCATTERED. BOTH THE NAM AND THE GFS PROVIDE FOR A 250MB 65KT JETLET MOVING ACROSS CENTRAL NORTH CAROLINA OVERNIGHT...WITH THE GFS BRINGING MORE HIGH CLOUDS WITH IT VERSUS THE NAM. ONCE AGAIN LEANING TOWARD THE NAM BASED ON IR TRENDS UPSTREAM...AND THOUGH THERE MAY BE SCATTERED TO THIN BROKEN HIGH CLOUDS DEVELOPING OVERNIGHT... BELIEVE THE BETTER CHANCE OF INCREASED HIGH OR MID LEVEL CLOUDS WILL BE DURING THE DAY SUNDAY WHEN BOTH THE GFS AND THE NAM SUGGEST EVEN STRONGER WINDS IN THE SOUTHWEST FLOW ALOFT WILL BE ENTERING THE CAROLINAS. THE COMBINATION OF LOW CLOUDS AND ANY HIGH CLOUDS MAY MAKE VARIABLY CLOUDY A GOOD SKY FORECAST OVERNIGHT. LOW TEMPERATURES OVERALL SHOULD BE AT LEAST A COUPLE OF DEGREES WARMER OVERNIGHT BASED ON GRADUALLY INCREASING DEEP LAYER MOISTURE...WITH PRECIPITABLE WATER VALUES INCREASING FROM AS LOW AS VALUES UNDER A HALF-INCH TOWARD KGSO... BEING AROUND AN INCH THROUGHOUT CENTRAL NORTH CAROLINA BY 12Z. ASIDE FROM POSSIBLE PATCHY FOG EARLY SUNDAY MAINLY NORTHEAST WHERE LOW CLOUDS MAY BE MORE SCATTERED ACCOMPANIED BY HIGHER DEWPOINTS...ANTICIPATE PARTLY SUNNY CONDITIONS AS A RULE SUNDAY AS ANY LOW CLOUDS GIVE WAY TO INCREASING UPPER-LEVEL MOISTURE. DESPITE WEAK UPPER-LEVEL DIFFLUENCE FORECAST WITH THE APPROACH AND PASSAGE OF JETLETS ALOFT...OVERALL ISENTROPIC DESCENT...SURFACE HIGH PRESSURE BUILDING SOUTH PROVIDING FOR GOOD SUBSIDENCE...AND SOUTHWARD MOVEMENT OF THETA-E TROUGHING ALL KEEP PRECIPITATION CHANCES AT BAY. THICKNESSES WOULD SUPPORT HIGHS IN THE UPPER 70S... IN LINE WITH THE CONSENSUS OF MOS. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... AS OF 205 PM SATURDAY... SUNDAY NIGHT THROUGH MONDAY NIGHT... THE UPPER LEVEL TROUGH/DISTURBANCE CURRENTLY OVER THE OZARKS WILL GRADUALLY SHEAR OUT AS IT MOVES EAST ACROSS THE AREA SUNDAY NIGHT THROUGH TUESDAY. VARYING AMOUNTS OF HIGH-LEVEL MOISTURE WILL ACCOMPANY THE UPPER TROUGH PASSAGE....BUT DRY CONDITIONS WILL PREVAIL AS PREDOMINATELY NORTHERLY FLOW THROUGH THE THE 1000-700 MB LAYER WILL RESULT IN A DRY 10 KFT SUB-CLOUD LAYER AND STABLE CONDITIONS. THE HIGH LEVEL CLOUDS WILL LIKELY IMPACT MIN TEMPERATURES SUNDAY NIGHT...BUT SHOULD HAVE LITTLE TO NO AFFECT ON AFTERNOON HIGHS MONDAY AFTERNOON AS LOW-LEVEL THICKNESSES RISE INTO THE 1390S...THE WARMEST DAY OF THE WEEK. LOWS 55 TO 60. HIGHS 80 TO 84. TUESDAY THROUGH TUESDAY NIGHT...DRY CONDITIONS CONTINUE ON TUESDAY AS CENTRAL NC LOOKS TO STAY ON THE ANTICYCLONIC SIDE OF THE AFOREMENTIONED WEAK UPPER LEVEL TROUGH ON TUESDAY...WHILE STRONG SFC RIDGING EXTENDS SOUTH INTO THE AREA FROM A PARENT HIGH LOCATED OVER NEW ENGLAND. GFS BUFR FORECAST SOUNDINGS INDICATE SOME MORNING STRATUS DEVELOPING...AND THEN LIFTING TO A SCATTERED STRATOCU LAYER IN THE AFTERNOON. THERE ARE GLARING DIFFERENCE IN THE LOW-LEVEL THERMAL STRUCTURE TUESDAY AFTERNOON...WITH THE NAM NEARLY 25 METERS WARMER THAN THE GFS. HIGHS IN THE MID TO UPPER 70S. LOWS IN THE MID TO UPPER 50S. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 205 PM SATURDAY... THERE IS GOOD OVERALL AGREEMENT IN THE LONG WAVE PATTERN DURING THE PERIOD FEATURING AN EXPANSIVE...YET FLAT SUBTROPICAL RIDGE THAT EXTENDS FROM THE SOCAL COAST...THROUGH THE CENTRAL PLAINS...AND ON INTO THE MID-ATLANTIC REGION. AT THE START OF THE PERIOD...A NEARLY STATIONARY UPPER-LEVEL TROUGH AND ASSOCIATED SFC FRONT OFF THE SOUTHEAST COAST WILL BE THE FOCUS FOR SOME UNSETTLED WEATHER OFFSHORE. HOWEVER...FOR SEVERAL DAYS NOW SOME OF THE NWP MODEL GUIDANCE HAVE BEEN INDICATING SIGNIFICANT CYCLOGENESIS (POSSIBLE SUBTROPICAL LOW DEVELOPMENT)OFF THE SE COAST BY THE END OF THE WORK WEEK. THIS IS WHERE FORECASTER CONFIDENCE TAKES A SHARP PLUNGE DOWNWARD AS MEDIUM RANGE MODELS STRUGGLE TO COME TO A CONSENSUS WITH THE EVOLUTION AND TRACK OF THE LOW PRESSURE CENTER...MORE SPECIFICALLY IF THE AREA OF LOW PRESSURE WILL RETROGRADE WESTWARD TOWARDS THE CAROLINAS...OR EVENTUALLY LIFT NORTH AND NORTHEAST...REMAINING WELL OFFSHORE. GIVEN THE HIGH AMOUNT OF UNCERTAINTY AT THIS TIME RANGE...WILL KEEP SLIGHT CHANCE POPS ACROSS THE EASTERN HALF OF THE FORECAST AREA FOR FRIDAY AND SATURDAY. A CONTINUATION OF AUTUMN LIKE TEMPERATURES WILL CONTINUE THROUGH THE PERIOD AS ANOTHER SEASONABLY DRY AND COOL SURFACE RIDGE BUILDS DOWN THE EASTERN SEABOARD. PROLONG PERIOD OF LOW-LEVEL ATLANTIC MARITIME ADVECTION COULD RESULT IN A CHALLENGING CLOUD FORECAST...QUITE SIMILAR TO THE PAST FEW DAYS. HIGHS IN THE MID TO UPPER 70S. LOWS IN THE MID TO UPPER 50S. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 205 PM SATURDAY... AS MENTIONED IN THE NEAR-TERM PORTION OF THE AFD...CLOUD FORECAST IS DIFFICULT OVERNIGHT. ANTICIPATE VFR CONDITIONS IN THE TRIAD... WITH AREAS OF MVFR STRATOCU OVERNIGHT AS LOW-LEVEL MOISTURE MOVES WEST. ELSEWHERE...LOW VFR/HIGH MVFR CEILINGS ARE EXPECTED TO TRANSITION TO MAINLY VFR WITH AREAS OF BROKEN STRATOCU BY AROUND MIDNIGHT AS LAYER ISENTROPIC LIFT BECOMES VERY WEAK OR DIMINISHES. WITH ENOUGH SCATTERING OF LOW CLOUDS AND GENERALLY LIGHT SURFACE WINDS...PERIODS OF IFR FOG ARE POSSIBLE AT KRWI. ANY REMAINING...LOCAL MVFR/IFR CONDITIONS WILL IMPROVE TO VFR BY 14Z SUNDAY. BOTH THE GFS AND NAM HAVE LIGHTER 925MB WINDS FORECAST IN CENTRAL NORTH CAROLINA 12Z SUNDAY VERSUS WHAT OCCURRED AROUND 12Z SATURDAY...AND THOUGH NORTHEAST WINDS OFF OF THE SURFACE SHOULD BE AS HIGH AS AROUND 20KT WITHIN THE FIRST 2000FT...BELIEVE LLWS THRESHOLDS WILL NOT BE MET. SURFACE HIGH PRESSURE BUILDING SOUTH SUNDAY SHOULD KEEP SUSTAINED WINDS 10KT OR LESS. VFR CONDITIONS SHOULD PERSIST SUNDAY NIGHT THROUGH MONDAY. THE GFS SHOWS THE POTENTIAL FOR MAINLY MORNING LOW CLOUDS TUESDAY THROUGH THURSDAY. DEPENDING ON HOW STRONG ANY LOW PRESSURE CENTER DEVELOPS OFFSHORE...PERIODS OF AFTERNOON GUSTY WINDS IN A TIGHTENING PRESSURE GRADIENT...IN ADDITION TO LATE NIGHT/EARLY MORNING LLWS... MAY OCCUR IN THAT PERIOD AS WELL. THIS IS PARTICULARLY TRUE IF THE GFS 925MB WIND SPEEDS APPROACHING OR JUST EXCEEDING 35KT VERIFY DURING LATE NIGHT PERIODS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...DJF SHORT TERM...CBL LONG TERM...CBL AVIATION...DJF nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREEN BAY WI 345 PM CDT SAT SEP 20 2008 .SHORT TERM...TONIGHT AND SUNDAY. COLD FRONT CURRENTLY MAKING ITS WAY SOUTHWESTWARD ACROSS THE FOX VALLEY LATE THIS AFTERNOON. WINDS HAVE NOW TURNED NORTHEAST AT MANITOWOC...GREEN BAY AND SHAWANO WITHIN THE PAST HOUR OR SO WITH RADAR FINE LINE SHOWING UP NICELY ON THE GRB WSR-88D. A FEW SHOWERS HAVE BEEN TRYING TO FORM OVER LAKE MICHIGAN...EAST OF STURGEON BAY...BUT HAVE BEEN STRUGGLING WITH PAULTRY AVAILABLE MOISTURE. SFC ANALYSIS INDICATES PRONOUNCED...BUT SHALLOW CONVERGENCE DEVELOPING AHEAD OF THE COLD FRONT OVER THE CENTRAL AND SOUTHWEST PORTION OF THE FORECAST AREA. SFC TEMPS HAVE ALSO CLIMBED TO AROUND 80 WITH DEW POINTS STILL AROUND 60. MODIFIED 20Z CWA AIRCRAFT SOUNDING AND 20Z RUC YIELD NOTABLE POSITIVE CAPE NEAR 1000 J/KG...BUT DEEP LAYER SHEAR VERY WEAK WITH LITTLE ADDITIONAL UPPER-LEVL SUPPORT. STILL CAN`T RULE OUT AN ISOLATED SHOWER OR POSSIBLY A THUNDERSTORM TO INITIATE NEAR THE COLD FRONT AS IT PUSHES INTO THE SOUTHEWST PORTION OF THE FORECAST AREA BETWEEN ABOUT 22Z AND 00Z. CAN ALSO EXPECT SOME GUSTY NORTHEAST WINDS NEAR LAKE MICHIGAN INTO THE EVENING AS TEMPS CONTINUE TO FALL THROUGH THE 60S. COLD FRONT SHOULD CONTINUE TO SAG INTO SOUTHWESTERN WISCONSIN OVERNIGHT AS HI PRESSURE BUILDS NORTH OF LAKE SUPERIOR OVERNIGHT INTO SUNDAY. INCREASING SOUTHERLY FLOW WILL DEVELOP WEST OF THE MISSISSIPI RIVER VALLEY SUNDAY AS HI PRESSURE DRIFTS INTO THE EASTERN GREAT LAKES. MOISTURE STILL APPEARS QUITE LIMITED...THUS DO NOT EXPECT MUCH IN THE WAY OF ANY PRECIP ALONG FRONTAL BOUNDARY AS IT STARTS TO HEAD BACK NORTHWARD LATE SUNDAY. WILL CONTINUE TO KEEP SUNDAY DRY DUE TO THE PERSISTENT DRY EASTERLY FLOW. FINALLY...DECIDED TO CONTINUE THE FROST ADVISORY IN COORD WITH MQT. ALTHOUGH SFC GRADIENT MAY BE A BIT STRONGER THAN PREVIOUS FCST...SFC DEWPOINT STILL QUITE LOW NORTH OF LAKE SUPERIOR WITH NOT A LOT CLOUDS UPSTREAM. GIVEN...LONGER NIGHTS AND PERHAPS A FEW HOURS OF LIGHT WINDS...SEEMED REASONABLE TO CONTINUE WITH ADVISORY LATER TONIGHT. .LONG TERM...MONDAY THROUGH NEXT SAT. FORECAST CONFIDENCE NOT EXTREMELY HIGH FOR THIS PERIOD AS TIMING AND LOCATION OF SEVERAL FAST MOVING SYSTEMS PROBLEMATIC. EARLY IN PERIOD...AREA IN RETURN FLOW ON BACKSIDE OF RETREATING SFC RIDGE. THAT`S ABOUT ALL THE MED RANGE MODELS AGREE ON AS DIVERGING SOLUTIONS THEN BECOME THE NORM AS SHORTWV TROF MOVS TOWARD AREA LATE TUE AND/OR WED. 20/12Z GFS APPEARS TO BE THE ODD MODEL OUT AS IT IS FASTER THAN 20/12Z NAM AND ECMWF. IN FACT... THE GFS HAS BEEN FLIP-FLOPPING A BIT ON TIMING OF SYSTEMS FOR THE UPCOMING WEEK. AT LEAST THE 20/00Z AND 20/12Z RUNS OF ECMWF HAVE SHOWN SOME SEMBLANCE OF CONSISTENCY. SIMILARLY...THE 20/12Z GFS IS FASTER WITH TIMING OF UPPER LEVEL JET AND SFC COLD FRONT FOR FRIDAY. WILL TREND TIMING OF BOTH SYSTEMS TWD THE SLOWER NAM/ECMWF SOLUTION. MAX/MIN TEMPS A BLEND OF GFS MOS AND HPC GUID...WHICH IS IN LINE WITH CURRENT GRIDS. THE SAME IS TRUE WITH DEWPT AND WIND GRIDS... LITTLE CHANGE WAS NEEDED. && .AVIATION...MAINLY VFR CONDITIONS EXPECTED TONIGHT AND SUNDAY. PATCHY AREAS OF MVFR TO IFR VSBYS DUE TO FOG IS POSSIBLE OVERNIGHT OVER NRN WI...ESPECIALLY AT RHI. && .MARINE...PERSISTENT NORTHEAST TO EAST WINDS ALONG THE LAKE MICH SHORELINE TONIGHT INTO SUNDAY WITH LONGER FETCH AND CAA WILL INCREASE WAVE ACTIVITY. SCA STILL IN EFFECT THROUGH 14Z SUNDAY. && .GRB WATCHES/WARNINGS/ADVISORIES... FROST ADVISORY FROM 3 AM TO 7 AM CDT SUNDAY FOR WIZ005-010>013. && $$ ESB/JKL wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 327 PM CDT SAT SEP 20 2008 .SHORT TERM... MAIN COLD FRONT WITH MORE PRONOUNCED WIND SHIFT WILL ENTER NORTHERN PORTIONS OF THE FORECAST AREA LATE THIS MORNING...THEN SAG SOUTH THIS EVENING. LITTLE UPPER LEVEL SUPPORT...AS TROUGH AXIS FROM SHORTWAVE NORTHEAST OF LAKE SUPERIOR HAS ESSENTIALLY ALREADY MOVED EAST. VERY WEAK WIND FIELDS THROUGHOUT. RUC SOUNDING ARE DRIER THAN 12Z NAM...INDICATING LITTLE DEEP MOIST CONVECTIVE POTENTIAL...WITH A WEAK CAP PREVENTING SURFACE BASED MOIST CONVECTION. LOCAL 4 KM WRF MODEL BASED ON LAPS DOES PRODUCE ISOLATED ECHOES...BUT MUCH OF THESE ARE ELEVATED...WITH ONLY A FEW SPOTS OF QPF. GFS AND ECMWF DEVELOPS AN UPPER LEVEL RIDGE OVER WISCONSIN SUNDAY...THAT SLOWLY REACHES THE EASTERN GREAT LAKES REGION MONDAY NIGHT. THIS BRINGS A LARGE SURFACE HIGH CENTERED NORTHEAST OF THE GREAT LAKES. .LONG TERM... A SHORTWAVE PUSHES ACROSS THE NORTHWESTERN U.S...WILL REACH THE NORTHERN ROCKIES ON SUNDAY. INITIAL SHORTWAVE HEADS NORTHEAST INTO CANADA...WITH WEAK TRAILING PVA EXTENDING INTO WISCONSIN ON MONDAY. SECONDARY UPSTREAM SHORTWAVE REACHES THE NORTHERN ROCKIES BY MONDAY NIGHT...THEN THE SHORTWAVES PUSHES INTO THE NORTHERN PLAINS ON TUESDAY...A BIT FASTER THAN YESTERDAYS RUNS. SHORTWAVE IS QUICKER ON GFS REACHING NORTHERN MINNESOTA TUESDAY AFTERNOON. SHORTWAVE IS FARTHER NORTH ON TODAYS RUNS...WITH UPPER RIDGE HOLDING MORE...ESPECIALLY ON ECMWF. 06Z DGEX IS EVEN LESS AMPLIFIED WITH THIS TROF. SHOWERS PUSH EAST INTO THE FORECAST AREA TUESDAY NIGHT...AND WEDNESDAY...WITH PRECIPITATION WEAKENING AS IT ADVANCES THROUGH THE FORECAST AREA. UPPER FLOW BECOMES MORE ZONAL ACROSS THE U.S. CANADIAN BORDER...RESULTING IN A WEAK TRAILING COLD FRONT AFFECTING THE AREA FRIDAY. && .AVIATION... WEAK COLD FRONT EXPECTED TO MOVE SOUTH THROUGH THE AREA THROUGH EARLY EVENING. LOCAL HIGH RESOLUTION MODELS SHOWING SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS FORMING ALONG AND AHEAD OF THE FRONT. GIVEN THE SCATTERED NATURE...WILL NOT MENTION IN TAFS AT THIS TIME. WIND SHIFT TO THE NORTHEAST SHOULD OCCUR AT TAF SITES BETWEEN 22Z SATURDAY AND 02Z SUNDAY. GUSTY WINDS EXPECTED FOR A TIME AT KMKE AND KENW...GIVEN CLOSE PROXIMITY TO LAKE MICHIGAN. DECENT TEMPERATURE INVERSION COMBINED WITH WEAKENING WINDS LATER TONIGHT SHOULD COMBINE FOR SOME MVFR FOG AT KMSN AND KENW...DIMINISHING BY MID MORNING SUNDAY. && .MARINE...WILL CONTINUE SMALL CRAFT ADVISORY FOR TONIGHT INTO SUNDAY MORNING FOR NOW...THOUGH LATEST MODELS SUGGEST CONDITIONS MAY BE MORE MARGINAL THAN PREVIOUSLY THOUGHT. WAVES MOST LIKELY TO REACH CRITERIA BASED ON FAVORABLE NORTHEAST FETCH WITH 10 TO 20 KNOT SUSTAINED WINDS. GUSTY NORTHEAST WINDS TO 22 KNOTS EXPECTED BEHIND FRONTAL PASSAGE FOR A TIME THIS EVENING. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 9 AM CDT SUNDAY FOR LMZ643>646. && $$ SHORT/LONG TERM...06/HENTZ AVIATION/MARINE...08/WOOD wi