AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 329 PM MDT SAT OCT 13 2007 .SHORT TERM... (TONIGHT AND SUNDAY) ...COMPLEX WEATHER PATTERN ANTICIPATED OVER THE NEXT 24 HOURS... ...ACCUMULATING SNOW CENTRAL MOUNTAINS/PIKES PEAK NEXT 24 HOURS... CURRENTLY...WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES SHOWED A MIDDLE/UPPER LEVEL LOW TRYING TO FORM OVER EASTERN UT WITH VIGOROUS SOUTHWEST FLOW OVER CO EARLY THIS AFTERNOON. FINALLY...MUCH OF THE IFR-MVFR STRATUS HAS DISSIPATED IN THE LOWER AR RIVER VALLEY AND SOUTHERN PALMER DIVIDE. WINDY SOUTHWEST SURFACE CONDITIONS HAVE FINALLY DEVELOPED IN THE SAN LUIS VALLEY WITH DEW POINTS TANKING INTO THE SINGLE DIGITS. ALSO...MOUNTAIN/HIGH VALLEYS DEW POINTS ARE STILL IN THE SINGLE DIGITS TO LOWER 20S...SO RELATIVELY DRIER AIR CONTINUES ALOFT. DEW POINTS IN THE 40S/LOWER 50S REMAIN ACROSS MUCH OF EASTERN CO PLAINS. RUC/LAPS INDICATES A RIBBON OF 100-600 J/KG CAPE GENERALLY ALONG THE I-25 CORRIDOR WITH THE HIGHER CAPE VALUES AROUND TELLER/EL PASO COUNTIES. HOWEVER...A CAPPING INVERSION IS PROHIBITING ANY SURFACE-BASED MOIST CONVECTION FROM DEVELOPING...SO FAR. THE GREATER THUNDERSTORM DEVELOPMENT HAS BEEN AROUND THE NORTHERN CO FRONT RANGE/SOUTHERN WY AND NORTHERN PALMER DIVIDE JUST AHEAD OF AN EJECTING SHORTWAVE TROUGH. THE 0-6KM SHEAR IS HEALTHY ACROSS MUCH OF CO WITH 50-85KTS GIVEN THE FAST SOUTHWESTERLY FLOW ALOFT JUXTAPOSED WITH RELATIVELY WEAK EAST SOUTHEASTERLY FLOW AT THE SURFACE. THIS AFTERNOON THROUGH SUNDAY...WELL THE SYSTEM TRACK WILL BE THE KEY TO ALL SENSIBLE WEATHER OVER THE NEXT 12-24 HOURS. STILL HAVE SOME SHORT RANGE MODEL VARIANCE ON THE 500MB LOW TRACK. IT APPEARS THE RUC40 IS A LITTLE FURTHER NORTH THAN THE NAM-WRF AND GFS. WILL PLAY A 500MB TRACK FROM JUST NORTH OF THE 4-CORNERS AREA AT 6PM SAT TO SALIDA TO 12AM SUN TO NEAR LIMON 6AM SUN TO NORTHEAST CO/NORTHWEST KS/SOUTHWEST NE BY 6PM SUN. MAY ACTUALLY SEE TWO PRECIPITATION PROCESSES TONIGHT. FIRST...SHOWERS AND THUNDERSTORMS SHOULD FORM GIVEN THE LATE AFTERNOON AND EVENING INSTABILITY WITH THE HIGHEST PROBABILITY AROUND THE CONTINENTAL DIVIDE INTO THE NORTHERN FRONT RANGE. PLAN TO MAINTAIN THE SEVERE THUNDERSTORM CHANCES AROUND EL PASO... PUEBLO INTO CROWLEY AND KIOWA CONTINUES LATE THIS AFTERNOON/EARLY EVENING GIVEN THE PREVIOUS CURRENT ANALYSIS MENTIONED. BY LATE TONIGHT...THIS EVOLVES INTO A MORE SYNOPTIC SCALE DRIVEN PRECIPITATION EVENT AS THE LOW APPROACHES AND SLIGHTLY STRENGTHENS DEVELOPING A COMA-CLOUD STRUCTURE. GIVEN THE PROJECTED PATH...THE WITH WEATHER SYSTEM/S STORM-RELATIVE QPF AXIS SHOULD BE FROM AROUND GUNNISON TO THE CENTRAL MOUNTAINS INTO THE NORTHERN FRONT RANGE INTO NORTHEAST CO AND NE. THE HEAVIEST QPF SHOULD BE IN THIS TRACK. ANY FAVORED OROGRAPHIC EFFECTS WOULD ENHANCE QPF VALUES WITHIN THE TRACK FOR CERTAIN AREAS LATER TONIGHT THROUGH SUNDAY. THE TRICKIEST SPOT WILL BE FREMONT...TELLER...AND EL PASO COUNTIES WHICH WILL BE ON THE SOUTHERN FRINGE OF THE POTENTIAL QPF AXIS. THE DEFORMATION ZONE CUSP COULD BE AROUND TELLER AND EL PASO COUNTIES BY SUNRISE SUNDAY. ANY SHIFT IN THE TRACK...COULD SIGNIFICANTLY INCREASE OR QPF CHANCES LATE TONIGHT/SUNDAY MORNING IN THIS POPULATED AREA. SNOW LEVEL WILL START OUT RELATIVELY HIGH LATE THIS AFTERNOON AND EVENING...AND LOWER THROUGH THE NIGHT TO AROUND 8K-7K FT MSL ACROSS THE CENTRAL MOUNTAINS...FREMONT COUNTY...TELLER COUNTY...AND EL PASO COUNTY. CURRENT SNOW ADVISORY LOOKS GOOD FOR THE SAWATCH AND MOSQUITO MOUNTAIN RANGES INCLUDING ALL OF LAKE COUNTY FOR TOTAL SNOW ACCUMULATION OF 3 TO 12 INCHES. FOR TELLER COUNTY...IF THINGS SETUP JUST PERFECT...WHICH WILL BE TRICKY...THERE COULD BE 1 TO 7 INCHES OF SNOW...ESPECIALLY FOR PIKES PEAK...SO WILL GO WITH A SNOW ADVISORY FOR LATE TONIGHT-SUNDAY MORNING. I STILL CANNOT RULE OUT 1 TO 4 INCHES OF SNOW ACROSS THE HIGHER ELEVATION OF THE PALMER DIVIDE AROUND 7K FT MSL...INCLUDING PALMER LAKE...MONUMENT...AND AIR FORCE ACADEMY...NEAR THE RAMPART RANGE VERY LATE TONIGHT/SUNDAY MORNING AND POSSIBLY THROUGH SUNDAY AFTERNOON. IT COULD BE THE PALMER DIVIDE HAS A MIXTURE OF RAIN/SNOW ALL DAY SUNDAY. AS THE LOW PULLS AWAY FROM SOUTHERN CO SUNDAY AFTERNOON...THE POTENTIAL DEFORMATION CLOUD/PRECIPITATION SHIELD SHOULD PULL AWAY FROM THE CENTRAL MOUNTAINS...TELLER AND EL PASO COUNTIES. GIVEN THE RELATIVE COLD POOL ALOFT...SHOWERS WILL BE POSSIBLE JUST ABOUT ANYWHERE SUNDAY AFTERNOON. ANTICIPATING SMALL DIURNAL TEMPERATURE SWINGS ACROSS THE MOUNTAINS/HIGH VALLEYS/PALMER DIVIDE/COLORADO SPRINGS SUNDAY GIVEN THE PRECIPITATION. METZE .LONG TERM... (SUNDAY NIGHT THROUGH SATURDAY) INITIAL CONCERN FOR THE LONG TERM WILL BE IMPACT DEPARTING CLOSED UPPER LOW WILL HAVE ON CWFA SUNDAY NIGHT. FOR NOW HAVE PAINTED AN ADDITIONAL 1 TO 3 INCHES OF SNOW OVER SECTIONS OF TELLER...NORTHERN EL PASO AND SELECT MOUNTAIN AREAS FROM 6 PM SUNDAY INTO MONDAY MORNING. AS CLOSED UPPER LOW INTO EASTERN NEBRASKA BY LATE MONDAY AND THEN INTO THE UPPER MIDWEST BY LATER TUESDAY...PROJECT THAT LOW GRADE TO NIL POPS SHOULD SUFFICE. FROM TUESDAY NIGHT INTO A GENERALLY ZONAL TO NORTHWEST FLOW PATTERN SHOULD BE IN PLACE OVER CWFA WITH LOW GRADE TO NIL POPS EXPECTED...WITH HIGHEST POP POTENTIAL FOCUSED MAINLY OVER THE CENTRAL MOUNTAINS. GRADIENT WINDS SHOULD BE ON THE DECREASE FROM SUNDAY NIGHT INTO TUESDAY AND THEN INCREASE AGAIN BY NEXT THURSDAY AND FRIDAY. FINALLY...MAXIMUM TEMPERATURES SHOULD RUN BELOW CLIMATOLOGICAL AVERAGES ON MONDAY AND THEN CLIMB TO SEASONAL AVERAGES FOR THE REMAINDER OF THE LONG TERM. && .AVIATION... GIVEN THE SHORT TERM DISCUSSION...COS WILL HAVE A CHANCE FOR MVFR- VFR TSRA AROUND THE AIRPORT LATE THIS AFTERNOON/EARLY EVENING. A MORE STEADY RAINFALL WILL LIKELY DEVELOP AFTER MIDNIGHT WITH MVFR CEILINGS AND VISIBILITIES. FOR PUB AND ALS AIRPORTS...VFR CEILING WILL BE LIKELY WITH ANY POTENTIAL RAINFALL LATE TONIGHT INTO SUNDAY. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... SNOW ADVISORY UNTIL 12 PM MDT SUNDAY FOR COZ058>061. SNOW ADVISORY FROM MIDNIGHT TONIGHT TO 12 PM MDT SUNDAY FOR COZ081-082. && $$ co AREA FORECAST DISCUSSION...UPDATED FOR ADDED RFW ZONES NATIONAL WEATHER SERVICE TALLAHASSEE FL 455 AM EDT SAT OCT 13 2007 .SYNOPSIS... 07Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING GENERAL TROUGHING OVER THE EASTERN THIRD OF THE NATION ANCHORED BY DOUBLE BARREL UPPER LOWS ACROSS SOUTHEASTERN CANADA. WV IMAGERY AND 00Z/13 SOUNDING PROFILES SHOWS VERY DRY MID/UPPER LEVELS (GENERALLY 800MB AND ABOVE) OVER THE SOUTHEAST AND MUCH OF THE GULF OF MEXICO. REGIONAL PW VALUES ARE RIGHT AROUND 0.40" (~33% OF NORMAL FOR MID OCTOBER). FURTHER UPSTREAM WE FIND RIDGING OVER THE CENTRAL PART OF THE CONUS AND A SECOND DEEP TROUGH COVERING THE WESTERN THIRD OF THE NATION. AT THE SURFACE...1017MB HIGH PRESSURE CENTERED OVER THE OHIO AND TENNESSEE VALLEYS CONTINUES TO DOMINATE THE SOUTHEASTERN STATES. MOSTLY CLEAR TO CLEAR SKIES ARE THE RULE. THESE CLEAR SKIES ARE COMBINING WITH LIGHT WINDS AND DRY LOW LEVELS TO PRODUCE VERY GOOD RADIATIONAL COOLING CONDITIONS ACROSS THE FORECAST AREA THIS EARLY MORNING. TEMPERATURES HAVE ALREADY FALLEN INTO THE UPPER 40S AND 50S ALMOST FORECAST AREA WIDE WITH THE EXCEPTION OF A FEW IMMEDIATE COASTAL LOCATIONS. && .SHORT TERM (TODAY-MONDAY NIGHT)... WEAK UPPER TROUGHING OVERHEAD BEGINS TO FLATTEN OUT THROUGH THIS EVENING BEFORE STRONG RIDGING BUILDS EAST ALONG THE GULF COAST INTO THE SOUTHEASTERN U.S TONIGHT THROUGH MONDAY MORNING. THE SURFACE HIGH CENTERED OVER THE TENNESSEE/OHIO VALLEYS WILL VERY SLOWLY PROGRESS EASTWARD TOWARD THE MID-ATLANTIC STATES THROUGH SUNDAY KEEPING CONTROL OF OUR LOCAL AREA INTO AT LEAST MONDAY. AFTER A VERY COOL START THIS MORNING...THE SHORT TERM WILL BE CHARACTERIZED BY DRY BUT INCREASINGLY WARM TEMPERATURES. ABUNDANT SUNSHINE WILL RAPIDLY WARM THE COOL MORNING TEMPERATURES INTO THE LOWER AND MIDDLE 80S. LIGHT NORTHERLY FLOW WILL COME AROUND TO THE NORTHEAST AND EAST THIS AFTERNOON AND EVENING ALLOWING FOR SOME ATLANTIC MOISTURE TO BEGIN ADVECTING BACK WESTWARD INTO OUR AREA. IT WILL STILL FEEL RATHER DRY THIS AFTERNOON BUT THE ADDITIONAL MOISTURE WILL START TO EFFECT RADIATIONAL COOLING CONDITIONS TONIGHT. INSTEAD OF WIDESPREAD UPPER 40S AND LOWER 50S ACROSS INLAND LOCATIONS...TONIGHT WILL COOL SLOWER WITH TEMPERATURES BOTTOMING OUT GENERALLY IN THE 50S AWAY FROM THE COAST AND LOWER 60S ALONG THE COAST. UPPER RIDGING BECOMES ESTABLISHED OVER THE SOUTHEAST SUNDAY INTO MONDAY WITH HIGH PRESSURE AT THE SURFACE CONTINUING TO NOSE DOWN THE EAST COAST INTO THE NORTHEAST GULF OF MEXICO. THE SURFACE AND UPPER LEVEL RIDGING WILL HELP KEEP THE FORECAST DRY INTO THE EARLY PART OF NEXT WEEK. IN ADDITION WILL CONTINUE TO SEE TEMPERATURES WARM WITH DAYTIME HIGHS GENERALLY IN THE MIDDLE 80S...WHICH IS SEVERAL DEGREES ABOVE AVERAGE. WINDS AROUND THE SURFACE HIGH FROM THE EAST WILL ALSO CONTINUE TO BRINGS A SLOW INCREASE IN LOW LEVEL MOISTURE WHICH WILL HELP TO BRING LOW TEMPERATURES UP A FEW DEGREES EACH NIGHT. EXPECTING TO SEE MOST LOCATIONS BACK ABOVE AVERAGE FOR LOW TEMPERATURES BY MONDAY NIGHT WITH UPPER 50S TO LOWER 60S COMMON AWAY FROM THE COAST AND MIDDLE 60 CLOSER TO THE WATER. && .LONG TERM (TUESDAY-FRIDAY)... AS IS SOMETIMES THE CASE DURING SEASONAL TRANSITIONS...THE GLOBAL MODELS ARE HAVING TROUBLE PINNING DOWN A SOLUTION FOR THE LATER PART OF THE FORECAST. THE ECMWF SEEMS TO BE DOING THE MOST FLIP-FLOPPING AT THIS POINT...AND THE LATEST 13/00Z RUN HAS TRENDED TOWARD THE 00Z GFS SOLUTION. FOR THIS REASON WILL LEAN MY EXTENDED GRIDS TOWARD THE GFS SOLUTION. STILL CONFIDENCE IN THIS EXTENDED FORECAST PACKAGE IS BELOW NORMAL. UPPER RIDGING EXITS EAST AND FLATTENS OUT BY EARLY TUESDAY AS TROUGHING DIGS INTO THE MISSISSIPPI VALLEY. GFS/ECMWF BOTH SHOW THIS TROUGHING HELPING TO PULL A WEAK SURFACE SYSTEM INTO THE WESTERN OR CENTRAL GULF OF MEXICO. INCREASING MOISTURE ON THE EASTERN SIDE OF THIS SYSTEM WILL BRING SLIGHT TO LOW END CHANCE POPS BACK INTO THE FORECAST BY THE END OF TUESDAY. THE MOISTURE HANGS AROUND THE NORTHEAST GULF COAST THROUGH THE MIDDLE PART OF THE WORK WEEK WITH THE GFS SHOWING A WEAK TROUGH REMAINING NEARLY STATIONARY OVER THE FORECAST AREA. WITH THIS IN MIND KEPT LOW END CHANCE POPS IN THE GRIDS. MEX NUMBERS WERE RATHER HIGH DURING THIS PERIOD AND GENERALLY BACKED DOWN THESE READINGS BY A COUPLE OF DEGREES...MAINLY DO TO THE EXPECTED CLOUD COVER AND POSSIBLE SHOWERS. ANOTHER TROUGH IS THEN ADVERTISED TO MOVE INTO THE CENTRAL AND EASTERN U.S DURING THE SECOND HALF OF THE FORECAST WITH A COLD FRONTAL PASSAGE THROUGH THE SOUTHEAST EITHER FRIDAY OR SATURDAY. && .AVIATION... VFR CONDITIONS WILL PREVAIL AT THE TERMINALS THROUGH THE THE PERIOD WITH SKC EXCEPT FOR SCT HIGH BASED AFTN CU MAINLY AT TLH...ABY AND VLD. ONLY POSSIBLY EXCEPTION TO VFR WILL BE VLD, WHERE INCREASING LOW LEVEL MOISTURE OFF THE ATLANTIC, AND VERY DRY AIR ALOFT MAY SET THE STAGE FOR SOME MVFR VISIBILITY RESTRICTIONS A COUPLE HOURS EITHER SIDE OF SUNRISE. && .MARINE... HIGH PRESSURE CENTERED TO THE NORTHEAST OF THE FORECAST WATERS REMAINS IN CONTROL INTO THE EARLY PART OF NEXT WEEK. WINDS OUT OF THE NORTH AND NORTHEAST WILL COME AROUND TO THE EAST TONIGHT INTO MONDAY. WITH THE EASTERLY FLOW A PERIOD OF CAUTIONARY CONDITIONS APPEARS LIKELY TONIGHT INTO SUNDAY MORNING AND AGAIN SUNDAY NIGHT INTO MONDAY MORNING. WINDS ARE THEN EXPECTED TO COME AROUND TO THE SOUTHEAST INTO THE MIDDLE PART OF NEXT WEEK WITH AN INCREASING CHANCE OF SCATTERED SHOWERS AND THUNDERSTORMS. && .FIRE WEATHER... NOT QUITE AS DRY TODAY AS HAS BEEN SEEN THE PAST FEW DAYS...HOWEVER WITH TEMPERATURES WARMING A FEW DEGREES WILL STILL BE EXPECTING CRITICAL FIRE WEATHER CONDITIONS ACROSS PORTIONS OF THE EASTERN FLORIDA PANHANDLE AND WESTERN FLORIDA BIG BEND AWAY FROM THE COASTLINE. RED FLAG WARNINGS ARE IN EFFECT FOR THESE AREAS. DOES APPEAR THAT ENOUGH ATLANTIC MOISTURE WILL BEGIN TO INFLUENCE THE AREA TO KEEP OUR SOUTHEASTERN FL BIG BEND ZONES FROM REACHING CRITICAL DURATIONS OF RH BELOW 35 PERCENT...HOWEVER IT WILL NEED TO BE WATCHED CLOSELY. OUR SOUTHEAST ALABAMA ZONES ARE ALSO LIKELY TO SEE A BRIEF PERIOD OF RH VALUES APPROACHING CRITICAL LEVELS...HOWEVER WINDS ARE EXPECTED TO BE LIGHT THIS AFTERNOON WHICH WILL KEEP RED FLAG CONDITIONS FROM BEING MET. NO FIRE WEATHER WATCHES OR WARNINGS ARE IN EFFECT AT THIS TIME FOR SUNDAY. RH VALUES MAY APPROACH 35 PERCENT FOR AN HOUR OR TWO ACROSS INLAND PORTIONS OF NORTHERN FLORIDA...HOWEVER CRITICAL DURATIONS ARE NOT ANTICIPATED AND DISPERSION INDICES SHOULD REMAIN BELOW 75. INCREASING LOW LEVEL MOISTURE SHOULD KEEP THE FIRE WEATHER THREAT LOW DURING THE EARLY AND MIDDLE PART OF NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 84 54 86 58 86 / 0 0 0 0 0 PANAMA CITY 83 62 86 65 86 / 0 0 0 0 05 DOTHAN 83 54 85 57 86 / 0 0 0 0 0 ALBANY 82 52 85 55 86 / 0 0 0 0 0 VALDOSTA 84 55 85 56 85 / 0 0 0 0 0 CROSS CITY 85 57 85 59 86 / 0 0 0 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...RED FLAG WARNING FROM 2 PM EDT /1 PM CDT/ TO 6 PM EDT /5 PM CDT/ THIS AFTERNOON FOR THE FOLLOWING ZONES: BAY... CALHOUN...FRANKLIN...GADSDEN...GULF...HOLMES... INLAND WALTON... JACKSON... JEFFERSON...LEON...LIBERTY... MADISON...WAKULLA...WASHINGTON. GM...NONE. && $$ AVIATION...BLOCK PUBLIC/MARINE/FIRE WX...MROCZKA fl AREA FORECAST DISCUSSION... NATIONAL WEATHER SERVICE TALLAHASSEE FL 400 AM EDT FRI OCT 12 2007 .SYNOPSIS... LOOKING AT THE 07Z WATER VAPOR AND H4 RUC ANALYSIS THE FEATURES THAT IMMEDIATELY STAND OUT ARE THE DOUBLE-BARREL UPPER LOWS OVER SOUTHEAST CANADA AND ALONG THE MID-ATLANTIC COASTLINE. TROUGHING THEN EXTENDS FROM THE MID-ATLANTIC LOW FURTHER SOUTH DOWN THE EAST COAST INTO THE NORTHEAST GULF OF MEXICO. FURTHER UPSTREAM WE SEE GENERAL RIDGING OVER MUCH OF THE PLAINS AND INTER-MOUNTAIN WEST. AT THE SURFACE HIGH PRESSURE CENTERED OVER THE MIDDLE MISSISSIPPI VALLEY NOW DOMINATES THE ENTIRE SOUTHEASTERN UNITED STATES. NORTHERLY FLOW ON THE EASTERN SIDE OF THIS HIGH CONTINUING TO DELIVER COOLER AND DRIER AIR TO THE FORECAST AREA. TEMPERATURES HAVE FALLEN INTO THE 50S ACROSS INLAND AREAS AND THROUGH THE 60S CLOSER TO THE COAST. SKIES ARE GENERALLY CLEAR REGION-WIDE. && .SHORT TERM (TODAY-SUNDAY NIGHT)... QUIET WEATHER PATTERN FOR THE SHORT TERM PERIOD AS SURFACE HIGH PRESSURE SLIDES EASTWARD TO OUR NORTH BUT REMAINS IN CONTROL OF THE SOUTHEASTERN STATES. FIRE WEATHER WILL BE THE MAIN ISSUE THE NEXT 48 HOURS...ESPECIALLY ACROSS NORTHERN FLORIDA. WILL SEE THE COLD AIR ADVECTION FROM THE NORTH BEGIN TO LESSEN TODAY AS THE SURFACE RIDGE GETS A BIT CLOSER AND ALLOWS THE PRESSURE GRADIENT TO RELAX. SOME WEAK TROUGHING IN THE MIDDLE AND UPPER LEVELS WILL CONTINUE OVERHEAD INTO SATURDAY BUT WILL HAVE LITTLE IMPACT ON OUR WEATHER. RIDGING THEN RETURNS FOR SUNDAY INTO MONDAY. AS A RESULT...POPS WILL REMAIN VERY LOW INTO THE FIRST PART OF NEXT WEEK. GUIDANCE IS RATHER TIGHTLY CLUSTERED FOR TEMPERATURES THIS AFTERNOON AND TONIGHT AND DID NOT DEVIATE MUCH FROM THE PREVIOUS FORECAST PACKAGE. WITH A BIT LESS MIXING EXPECTED TODAY...HIGHS SHOULD TOP OUT IN THE UPPER 70S TO LOWER 80S FOR MOST LOCATIONS. GRADIENT REMAINS RATHER RELAXED FOR THE OVERNIGHT PERIOD AND THIS COMBINED WITH EXPECTED CLEAR SKIES SHOULD ALLOW FOR DECENT RADIATIONAL COOLING CONDITIONS. TEMPERATURES ARE EXPECTED TO ONCE AGAIN FALL INTO THE UPPER 40S TO MIDDLE 50S AWAY FROM THE COAST. A SLOW WARMING TREND WILL THEN BEGIN OVER THE WEEKEND INTO THE FIRST PART OF NEXT WEEK. WITH FAIRLY STRONG UPPER RIDGING BUILDING BACK BY SUNDAY...WILL LIKELY SEE HIGH TEMPERATURES BACK ABOVE AVERAGE WITH MIDDLE TO UPPER 80S COMMON. && .LONG TERM (MONDAY-FRIDAY)... UPPER AND SURFACE RIDGING STILL IN CONTROL OF THE AREA FOR MONDAY WITH DRY WEATHER AND WARM TEMPERATURES. GLOBAL MODELS SHOWING NEXT FRONT MOVING INTO THE MISSISSIPPI VALLEY MONDAY NIGHT AND EARLY TUESDAY. HOWEVER AS THE FRONT AND ASSOCIATED MID LEVEL TROUGH MOVE EAST TUESDAY NIGHT AND WEDNESDAY...THE BULK OF THE MID LEVEL ENERGY HEADS WELL NORTH OF OUR FORECAST AREA AND BOTH THE GFS AND ECMWF SHOW THE SURFACE FRONT WASHING OUT. AT THIS POINT...CAN NOT JUSTIFY MUCH MORE THAN A SLIGHT CHANCE POP FOR TUESDAY INTO WEDNESDAY. WITH THE FRONT NEVER REACHING OUR AREA...TEMPERATURES LOOK TO REMAIN ABOVE AVERAGE THROUGH A MAJORITY IF NOT ALL OF THE EXTENDED PERIOD. GLOBAL MODELS THEN SHOW THE NEXT POTENTIAL SYSTEM APPROACHING TOWARD THE END OF NEXT WEEK. && .AVIATION...VFR CONDITIONS WILL PREVAIL AT THE TERMINALS THROUGH THE PERIOD. && .MARINE... HIGH PRESSURE CENTERED OVER THE MIDDLE MISSISSIPPI VALLEY WILL CONTINUE TO BUILD OVER THE COASTAL WATERS THROUGH TODAY. A FAIRLY TIGHT GRADIENT HAS RAISED WINDS TO CAUTIONARY LEVELS EARLY THIS MORNING AND EXPECT THESE WINDS TO REMAIN ELEVATED UNTIL THE GRADIENT RELAXES LATER THIS MORNING OR EARLY THIS AFTERNOON. HIGH PRESSURE WILL SLIDE TO THE NORTH OF THE COASTAL WATERS THIS WEEKEND ALLOWING WINDS TO COME AROUND TO THE NORTHEAST AND EVENTUALLY EAST. A PERIOD OF CAUTIONARY CONDITIONS IS AGAIN POSSIBLE SATURDAY NIGHT INTO SUNDAY MORNING. WINDS REMAIN GENERALLY FROM THE EAST DURING THE EARLY PART OF NEXT WEEK WITH A PERIOD OR TWO OF NEAR CAUTIONARY CONDITIONS POSSIBLE...ESPECIALLY DURING THE OVERNIGHT AND EARLY MORNING HOURS. && .FIRE WEATHER... RED FLAG WARNINGS REMAIN IN EFFECT FOR ALL OF OUR FLORIDA ZONES THIS AFTERNOON AND EARLY EVENING DUE TO CRITICAL DURATIONS OF RELATIVE HUMIDITY BELOW 35 PERCENT. RH VALUES ARE LIKELY TO FALL BELOW 30 FOR SEVERAL HOURS ACROSS PORTIONS OF SOUTHEAST ALABAMA...HOWEVER WINDS ARE ANTICIPATED TO REMAIN RATHER LIGHT AND NOT ALLOW RED FLAG CONDITIONS TO BE MET. NOT QUITE AS DRY IN THE LOW LEVELS FOR SATURDAY...BUT GRIDS STILL SHOWING CRITICAL RH VALUES FOR A TIME OVER PORTIONS OF THE EASTERN FLORIDA PANHANDLE AND FLORIDA BIG BEND. ALTHOUGH CRITICAL DURATIONS ARE NOT MET...ONLY A SMALL DECREASE IN THE DEWPOINTS WOULD RESULT IN RED FLAG CONDITIONS...FOR THIS REASON WILL ISSUE A FIRE WX WATCH FOR ALL BUT TAYLOR...DIXIE AND LAFAYETTE COUNTIES AND LET THE FOLLOWING SHIFT RE-EVALUATE THE THREAT. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 80 51 82 57 86 / 0 0 0 0 0 PANAMA CITY 80 58 83 62 86 / 0 0 0 0 0 DOTHAN 79 49 82 53 87 / 0 0 0 0 0 ALBANY 79 48 82 52 86 / 0 0 0 0 0 VALDOSTA 80 53 82 55 85 / 0 0 0 0 0 CROSS CITY 81 55 84 58 86 / 0 0 0 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...RED FLAG WARNING FROM 1 PM EDT /NOON CDT/ THIS AFTERNOON TO 7 PM EDT /6 PM CDT/ THIS EVENING FOR THE FOLLOWING ZONES: BAY... CALHOUN...DIXIE...FRANKLIN...GADSDEN...GULF...HOLMES... INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE...LEON... LIBERTY...MADISON...TAYLOR...WAKULLA...WASHINGTON. FIRE WEATHER WATCH SATURDAY AFTERNOON FOR THE FOLLOWING ZONES: BAY...CALHOUN...FRANKLIN...GADSDEN...GULF...HOLMES...INLAND WALTON...JACKSON...JEFFERSON...LEON...LIBERTY...MADISON... WAKULLA...WASHINGTON. GM...NONE. && $$ AVIATION...BLOCK PUBLIC/MARINE/FIRE WX...MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 239 PM MDT SAT OCT 13 2007 .DISCUSSION... PRIMARY CONCERNS THROUGHOUT THE PERIOD WILL BE PRECIPITATION CHANCES THROUGH THE PERIOD. 16Z WATER VAPOR IMAGERY/RUC ANALYSIS INDICATING STRONG SHORTWAVE TROUGH NEARING THE FOUR CORNERS AREA. H3 RAOBS INDICATE 100KT JET STREAK JUST AT THE BASE OF THE TROUGH...AND H5 HEIGHT FALLS WOULD INDICATE TROUGH BEGINNING TO LIFT NORTHWARD. AT THE SFC...FRONTAL BOUNDARY STRETCHED FROM SOUTHWEST KS TO NEAR KGBD. A SFC LOW WAS CENTERED ACROSS NORTHEAST NEW MEXICO...WITH A SECOND LOW TO THE NORTH OF KDDC. BOTH THE NAM AND GFS INITIALIZED REASONABLY WELL...ALTHOUGH THEY SEEMED SEVERAL C TO WARM AT H7 AT KLBF...BUT SOUNDING DOES HAVE A LARGE SUPERADIABATIC LAYER THAT LOOKS QUESTIONABLE. MODELS STILL HAVING A TOUGH TIME HANDLING SYSTEM COMING OUT OF THE ROCKIES...WITH UKMET AND GFS NOW FORECASTING A MORE ELONGATED TROUGH. NAM...00Z ECMWF...AND SREF MEAN TEND TO FAVOR THE NAM SOLUTION WHICH HAS HAD DECENT RUN TO RUN CONTINUITY AND WILL LEAN IN THIS DIRECTION. TONIGHT...SEVERAL FORECAST CONCERN FOR THIS PERIOD INCLUDING SEVERE WX...FOG AND PRECIPITATION CHANCES. WARM FRONT...WHICH CURRENTLY WELL TO THE SOUTH OF THE AREA WILL SLOWLY BEGIN TO LIFT NORTH LATE THIS AFTERNOON AS STRONG TROUGH BEGINS TO OVERSPREAD THE AREA. STRONG CAP WAS OBSERVED ON KDDC SOUNDING...AND MODELS CONTINUE TO HOLD ONTO A STRONG CAP THROUGH THE AFTERNOON AND EARLY EVENING AND WITH WIDESPREAD STRATUS AND FOG THAT SEEMS REASONABLE. HOWEVER AM A LITTLE CONCERNED ABOUT THE POTENTIAL FOR SFC BASED STORMS IN THE EXTREME EAST NEAR A WEAK SFC LOW AS CLOUDS STARTING TO BREAK UP IN THIS REGION. WITH INCREASING FLOW ALOFT TONIGHT...NEARLY 60KTS OF SHEAR DEVELOP ABOVE THE SFC INVERSION SO ROUND OF SEVERE WX DEFINITELY LOOKS POSSIBLE TONIGHT...REGARDLESS OF WHETHER OR NOT A SFC BASED STORM CAN DEVELOP. PRECIPITATION SHOULD BECOME MORE WIDESPREAD AS Q VECTORS INDICATE FAIRLY WIDESPREAD FORCING FOR ASCENT. H7 AND H85 WAA FIELDS ALONG WITH 305K ISENTROPIC FIELDS ALL LINE UP WITH BEST DIV Q FORCING ACROSS THE NORTHWEST...AND WILL KEEP BEST CHANCES IN THIS AREA. FOG DEVELOPMENT LOOKS LIKE A GIVEN TONIGHT AS MANY AREAS WILL LIKELY STILL BE EXPERIENCING FOG THROUGH THE DAY. AM CONCERNED ABOUT DENSE FOG POTENTIAL...BUT PRECIPITATION...WIDESPREAD ASCENT AND LIKELY DRIZZLE FORMATION SHOULD KEEP VISBYS FROM BOTTOMING OUT...BUT AM GOING TO MAKE A LAST MINUTE CALL ON POSSIBLE ADVISORY. SUNDAY-MONDAY...H5 LOW WILL SLOWLY BEGIN TO MOVE OUT OVER THE AREA ON SUNDAY MORNING. WITH THE LOWS POSITION ACROSS THE NORTHWEST AND FRONTAL ZONE DRAPED FROM NORTH TO SOUTH...STRONGEST FORCING WILL REMAIN ACROSS THE NORTHERN CWA AND WILL TAILOR POPS ACCORDINGLY. NAM STILL SUGGESTING POSSIBILITY OF SFC BASED TSTMS NEAR THE LOW CENTER/WARM FRONT ACROSS THE NORTHEAST CWA. SEEMS UNLIKELY AT THIS POINT...BUT WITH COLD H5 LOW MOVING OVER THE AREA...PLENTY OF SHEAR AND MOISTURE...CANT RULE OUT SOMETHING DEVELOPING IN THIS AREA. UPPED POPS IN THE NORTH AS ALL MODELS BEGINNING TO FOCUS IN ON THIS AREA FOR PRECIP DEVELOPMENT. ISENTROPIC FIELDS BEGIN TO INDICATE STRONG DOWNGLIDE DEVELOPING AFTER 00Z AS LOW BEGINS TO MOVE EAST...WITH CAA UP TO H7 BY 06Z. WILL BEGIN TO LOWER POPS AFTER THIS TIME PERIOD AS SUBSIDENCE BEGINS TO SET IN ACROSS THE AREA...BUT WILL KEEP CHANCE POPS GOING TO ACCOUNT FOR TIMING UNCERTAINTY. BY MONDAY MORNING PRECIPITATION SHOULD BE ON THE DECLINE EVERYWHERE...AS DEEP WILL OVERSPREAD THE AREA BY 15Z. SOUNDINGS ACTUALLY SUGGEST POTENTIAL FOR SHALLOW CONVECTION TO DEVELOP IN THE AFTERNOON. THESE WILL MOST LIKELY BE SPRINKLES...BUT WILL HOLD ON TO LOW POPS THROUGH THE DAY. ANOTHER CONCERN WILL BE THE POTENTIAL FOR ANY PHASE CHANGE OF PRECIPITATION...AS COLDER AIR WILL BEGIN BUILDING INTO THE AREA ON SUNDAY AFTERNOON. COLDEST MODEL DATA STILL SUPPORTS ALL RAIN...BUT WITH POSSIBILITY OF WET BULB EFFECTS AND RADIATIONAL COOLING MAY SEE A FEW FLAKES IN THE WEST. SET UP LOOKS VERY MARGINAL AS ICE GENERATION LEVELS WILL BE DRYING OUT AS COLD AIR MOVES IN...BUT WORTH A SMALL MENTION OF RA/SN EARLY MONDAY MORNING IN THE WEST. MONDAY-NIGHT-TUESDAY...H5 RIDGING WILL BE BUILDING INTO THE AREA AS LOW FINALLY MOVES TO THE EAST. HIGH PRESSURE WILL BE SETTLING OVER THE AREA BEHIND THIS WEEKENDS SYSTEM. WITH CLEARING SKIES AND A COOLER...DRIER AIRMASS IN PLACE THINK TUESDAY MORNING COULD BE PRETTY COLD. LOWERED TEMPS A FEW DEGREES AND ADDED FROST TO FORECAST FOR MUCH OF THE AREA. ON TUESDAY...WARM FRONT WILL BEGIN TO LIFT TO THE NORTH ACROSS THE AREA. WITH LITTLE SFC MOISTURE AROUND THE AREA EXPECT LITTLE IN THE WAY OF WX...BUT HIGH TEMPS SHOULD REBOUND 15 OR SO DEGREES ABOVE MONDAY. IN THE EXTENDED...FIRST LOOK AT THE MEDIUM RANGE MODELS SHOWS LITTLE IN THE WAY OF RUN TO RUN CONSISTENCY BETWEEN GFS AND ECMWF. ECMWF HAS NOW ABANDONED ITS H5 TROUGH SOLUTION FOR THUR-FRI...BUT GFS NOW BEGINNING TO SHOW SIGNS OF THIS FEATURE. WITH ALL THE CHANGES BETWEEN THE MODELS BETWEEN RUN TO RUN...HARD TO GET TO EXCITED ABOUT ANY ONE SOLUTION AND PLAN TO LEAN HEAVILY OF ENSEMBLE MEAN DATA FOR THE FORECAST. GFS ENSEMBLE MEMBERS CONTINUE TO SHOW A FEW MEMBERS WITH A STRONGER...DEEPER TROUGH ON THURSDAY...BUT ALSO HAVE SEVERAL MEMBERS THAT ARE MUCH WEAKER...WHICH ALSO LEADS ME TO LEAN MORE ON MEAN ENSEMBLE DATA. OVERALL MADE RELATIVELY MINOR CHANGES TO GOING FORECAST. && .AVIATION... THROUGH 18Z WILL SEE A CONTINUATION OF STRATUS AND FOG. CIGS AROUND 500 FT OR SO. DENSE FOG WITH VIS 1/4 MILE EXPECTED AFTER MIDNIGHT IF PRECIP DOESNT FALL. IF PRECIP DEVELOPS OVER THE TAF SITES CIGS/VIS A BIT HIGHER BUT AFTER 08Z OR SO AM EXPECTING PRECIP MAINLY NORTH OF THE AREA. BY 18Z OR SO SUNDAY WINDS WILL SHIFT TO THE NORTHWEST WITH GUSTY CONDITIONS AT KGLD. CIGS WILL START TO RISE BUT STILL IN THE MVFR/IFR RANGE. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ JRM/DDT ks AREA FORECAST DISCUSSION...CORRECTED TIME NATIONAL WEATHER SERVICE GOODLAND KS 250 PM MDT FRI OCT 12 2007 .DISCUSSION... 17Z WATER VAPOR IMAGERY AND RUC ANALYSIS INDICATES RIDGING ACROSS THE CENTRAL PLAINS WITH STRONG SHORT WAVE TROUGH BEGINNING TO MOVE ONTO THE NORTHERN CALIFORNIA COAST...WHERE 12Z RAOBS INDICATE LARGEST 12 HR HEIGHT FALLS ARE OCCURRING. AREA OF CONVECTION CONTINUED ACROSS CENTRAL KANSAS ALONG NOSE OF LLJ WHERE 300K ISENTROPIC ANALYSIS INDICATES STRONG MOISTURE ADVECTION. AT THE SFC...LOW PRESSURE CENTER WAS LOCATED ACROSS SOUTHEAST COLORADO NEAR KSPD...WITH WIDESPREAD STRATUS/FOG ACROSS THE GOODLAND CWA WITH EVEN A BIT OF DRIZZLE OBSERVED ALONG THE KS AND CO BORDER. BOTH THE NAM AND THE GFS APPEARED TO INITIALIZE OKAY...WITH NO LARGE ERRORS NOTED. NAM/GFS/UKMET IN REASONABLE AGREEMENT WITH THE SYNOPTIC PATTERN THROUGH THE PERIOD...BUT BEGIN TO DIVERGE WITH THE EXACT OF THE SYSTEM SUNDAY. NAM IS THE FASTEST AND FARTHEST NORTH WITH THIS SYSTEM...WITH THE GFS SLOWEST AND FARTHEST SOUTH. UKMET AND SREF MEAN ARE SOMEWHERE IN THE MIDDLE AND WILL LIKELY LEAN THIS WAY WITH THE FORECAST. TONIGHT...MAIN CONCERNS THROUGH THIS PERIOD WILL CENTER AROUND FOG AND ANY PRECIPITATION CHANCES. PATTERN LOOKS VERY SIMILAR TO LAST NIGHT WITH DEVELOPMENT OF LLJ. MASS CONVERGENCE FIELDS WOULD SUPPORT ANOTHER ROUND OF LLJ FORCING OVERNIGHT...WITH FAIRLY STRONG ISENTROPIC ASCENT NOTED ON THE 305 AND 310 K SURFACE. MORNING ISENTROPIC ANALYSIS INDICATES A TONGUE OF HIGH MIXING RATIOS DOWNSTREAM OF THE AREA ON THIS SURFACE. SOUNDINGS ALSO APPEAR FAVORABLE TO SUPPORT DRIZZLE REDEVELOPING AGAIN OVERNIGHT...BUT FOR NOW WILL LEAVE OUT FOR MUCH OF THE AREA AS ALREADY HAVE THUNDER CHANCES. WITH NEARLY SATURATED CONDITIONS ALREADY IN PLACE...ONLY HAVE LOWS A FEW DEGREES COOLER THAN CURRENT TEMPS IN THE NORTHWEST WHERE STRATUS WILL REMAIN IN PLACE ALL EVENING. TOMORROW-TOMORROW NIGHT...ONGOING STRATUS AND FOG WILL BE THE FIRST PROBLEM OF THE DAY...AND WILL LIKELY HOLD DOWN TEMPERATURES SIGNIFICANTLY THROUGH THE MORNING. FOCUS THEN TURNS TO WARM FRONT THAT SHOULD SLOWLY BEGIN TO LIFT NORTHWARD THROUGH THE DAY. BOTH THE NAM...GFS AND SREF INDICATE THAT STRONG CAP WILL BE IN PLACE ALONG THE FRONT SO AM NOT THAT CONFIDENT THAT SFC BASED TSRA WILL DEVELOP DURING THE AFTERNOON...SO WILL NOT GET TO HIGH ON POPS. STRONG H5 TROUGH WILL BEGIN TO OVERSPREAD THE AREA DURING THE NIGHT. ISENTROPIC FIELDS...ALONG WITH DIV Q FIELDS INDICATE STRONGEST LIFT SHOULD BE LOCATED TO THE NORTH OF THE WARM FRONT ACROSS THE NORTHWEST CORNER OF THE CWA AND JUST TO THE EAST OF THE CWA. RIGHT NOW MODELS SEEM TO KEEP AREA ON THE FRINGE OF THINGS...BUT ENOUGH UNCERTAINTY REMAINS TO KEEP HIGH CHANCE POPS ACROSS THE AREA. SUNDAY-MONDAY...H5 LOW WILL BE LIFTING ACROSS THE AREA. GFS INDICATING A FAIRLY STRONG DRY SLOT DEVELOPING WITH THIS SYSTEM AS NOTED ON THE 305K SFC. THIS WILL POSE THE BIGGEST PROBLEM FOR THE FORECAST ON SUNDAY. AS GFS IS THE SOUTHERNMOST SOLUTION...AND THE MORE NORTH THE TROUGH COMES OUT...A LARGER PORTION OF THE CWA WILL BE DRY SLOTTED. WILL CONTINUE TO KEEP IDEA OF BEST CHANCE FOR PRECIP IN THE NORTH AND EAST. GFS SHOWS SOME POTENTIAL FOR SFC BASED STORMS EARLY SUNDAY AFTERNOON WITH PRETTY STRONG 0-1KM SHEAR AND LOW LCL/LFC`S...SO WILL NEED TO KEEP AN EYE ON THIS DAY FOR SEVERE WX POTENTIAL. TROUGH SHOULD BE LIFTING OUT OF THE AREA ON MONDAY...ALTHOUGH WITH SUCH LARGE DIFFERENCES IN THE MODELS AM GOING TO HOLD ON TO POPS THROUGH THE DAY. IN THE EXTENDED...MEDIUM RANGE MODELS BEGIN TO DIVERGE FROM ONE ANOTHER FAIRLY QUICKLY IN THE EXTENDED PERIODS...WITH NUMEROUS TIMING AND AMPLITUDE DIFFERENCES THROUGHOUT THE PERIOD. 00Z GFS APPEARED TO BE A MAJOR OUTLIER WHEN COMPARED TO H5 ENSEMBLE MEAN AND MEMBERS WITH A LARGE NUMBER OF MEMBERS SHOWING A SLOWER...STRONGER...AND FARTHER SOUTH SOLUTION. 06Z GFS WAS CLOSER TO ITS ENSEMBLE MEAN...BUT THERE REMAINS A LARGE NUMBER OF MEMBERS THAT LOOK A LOT LIKE THE ECMWF SO THINK WILL LEAN THIS WAY IN THE FORECAST BUT OVERALL CONFIDENCE IN THE DETAILS IS LOW. ADDED AND INCREASED POPS THROUGH THE THUR-FRI TIMEFRAME...BUT DUE TO THE UNCERTAINTY WILL JUST KEEP LOW CHANCE POPS FOR NOW. TAKING THE ECMWF LITERALLY STILL KEEPS PRECIP TYPE RAIN DURING THIS TIME FRAME...ALTHOUGH CHANGEOVER LINE GETS PRETTY CLOSE TO EASTERN CO BUT AS THERE IS NO STRONG CONSENSUS ON SOLUTIONS THINK KEEPING THINGS ALL RAIN IS THE WAY TO GO. FOR TEMPS...GENERALLY MADE ONLY MINOR CHANGES. DID COOL OFF MIN TEMPS SEVERAL DEGREES ON TUESDAY MORNING AS MODELS ALL AGREE THAT HIGH PRESSURE WILL BE SETTLING OVER THE AREA...AND MAY SEE SOME WIDESPREAD FROST. && .AVIATION... THROUGH 18Z AM EXPECTING STRATUS TO REMAIN OVER BOTH KGLD AND KMCK SITES. MVFR AND/OR IFR CONDITIONS WILL PREVAIL ON LIGHT EAST TO NORTHEAST WINDS. FOG WILL DEVELOP BUT THE EXTENT OF IT REGARDING HOW LOW VISIBILITIES WILL BE IS ALWAYS DIFFICULT BUT ITS FAIRLY CERTAIN IT WILL DEVELOP. SHOWERS AND THUNDERSTORMS EXPECTED AGAIN AFTER MIDNIGHT WITH BEST CHANCE OVER THE KMCK AREA VS KGLD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ JRM/DDT ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1025 AM MDT FRI OCT 12 2007 .UPDATE...AT 15Z HAND ANALYSIS SHOWS SURFACE LOW OVER SOUTHEAST COLORADO WITH A WARM FRONT PER SOUTHERLY WINDS INTO AREAS SOUTH OF INTERSTATE 70. SAT DATA SHOWING WIDESPREAD STRATUS ACROSS THE AREA WITH FOG OVER THE WESTERN 1/2 OF THE AREA. FOR THE MORNING UPDATE HAVE RELIED HEAVILY ON THE 15Z RUC WHICH IS GENERALLY SIMILAR TO PRIOR RUNS AND THE 12Z NAM. AM EXPECTING THE STRATUS TO CONTINUE ALL DAY WITH PERHAPS A FEW BREAKS BY EARLY AFTERNOON ACROSS THE WEST AND SOUTH AS HIGHEST 850-800 RH MOVES SLOWLY EAST WITH A MORE NORTHERLY COMPONENT TO THE WIND AS WELL. FOG WILL ALSO START TO DEVELOP GENERALLY NORTH OF THE INTERSTATE WHERE LOW LEVEL MOISTURE ALSO HIGHEST. TEMPERATURE FORECAST SHOWS SIGNIFICANTLY COOLER MAX TEMPS AS A RESULT WITH 55 TO 60 GENERALLY ALONG AND NORTH OF THE INTERSTATE WITH MID 60S TO NEAR 70 IN THOSE AREAS WHERE SOME BREAKS IN THE CLOUD COVER ARE EXPECTED. FURTHER UPDATES MAY BE NEEDED IF THE CLOUD COVER DISSIPATES FASTER THEN CURRENTLY EXPECTED. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ DDT ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 301 AM CDT FRI OCT 12 2007 .DISCUSSION... PRIMARY FORECAST CONCERNS REMAIN FOCUSED ON PROBABILITY OF CONVECTION PRIOR TO AND DURING ARRIVAL OF UPPER LEVEL LOW PRESSURE SYSTEM. AS OF EARLY THIS MORNING...ISOLATED CONVECTION HAS DEVELOPED OVER PORTIONS OF NORTH CENTRAL KANSAS. THIS IS WITHIN THE LEADING EDGE OF WARM AIR/MOISTURE ADVECTION JUST ABOVE THE SURFACE. EXPECT ACTIVITY TO BECOME A LITTLE MORE SCATTERED THROUGH THE MORNING HOURS...WITH ACTIVITY GRADUALLY SHIFTING EASTWARD. ELEVATED CONVECTION WILL BECOME MORE WIDESPREAD WITH TIME AS CYCLOGENESIS OVER SOUTHEAST COLORADO AND ATTENDANT WARM FRONT OVER PORTIONS OF THE CWA PROVIDE A FOCUS/LIFT FOR CONVECTIVE DEVELOPMENT TONIGHT INTO SATURDAY MORNING. EXPECT WARM FRONT TO LIFT NORTH OF THE REGION SATURDAY AFTERNOON/EVENING WHICH WILL REDUCE PROBS OF CONVECTION. THUNDERSTORMS SHOULD DEVELOP ALONG A DRYLINE IN WESTERN KANSAS SATURDAY NIGHT ALLTHEWHILE THE DRYLINE RETROGRADES BY LATE EVENING. EVEN THOUGH THE SURFACE FOCUS WILL REMAIN WEST OF THE CWA...SPAWNED CONVECTION OVER W KS WILL TRANSLATE NORTHEASTWARD AND BECOME ELEVATED WITH TIME. SOME OF THIS ACTIVITY MAY ARRIVE IN THE WESTERN ZONES LATE SATURDAY NIGHT INTO SUNDAY MORNING. IN ADDITION...A FEW MODEL SOLUTIONS ARE SUGGESTIVE OF CONVECTION TO DEVELOP OUT AHEAD. THEREFORE...RETAINED AND MASSAGED ONGOING POP FORECAST. SUNDAY INTO SUNDAY NIGHT...LARGE UPPER LOW FINALLY EJECTS INTO THE CENTRAL PLAINS STATES. VARIOUS MODEL SOLUTIONS FOR PLACEMENT OF SFC LOW AT 00Z MON...NAM AT KEARNEY, NE...GFS AT STOCKTON, KS...EURO AT PHILLIPSBURG, KS. THE GOOD NEWS IS THE FORWARD PROGRESSION AND OTHER SURFACE FEATURES ARE IN FAIRLY GOOD AGREEMENT. THEREFORE...TOOK A BLEND OF THE SOLUTIONS...WITH THE IDEA THAT ROBUST CONVECTIVE DEVELOPMENT IS LIKELY ALONG A DRYLINE AND AHEAD OF THE SFC LOW BY EARLY/MID AFTERNOON OVER WESTERN/CENTRAL KANSAS. THIS ACTIVITY WILL SHIFT NORTHEAST/EASTWARD TOWARDS THE CWA. SEVERE WEATHER POTENTIAL WILL BE DEPENDANT ON AMOUNT OF SFC HEATING REALIZED DURING SUNDAY MORNING/AFTERNOON. ATTM...BEST CHANCE OF SVR WILL BE WESTERN ZONES OF THE CWA. FUTURE FORECASTS WILL BETTER REFINE ASSOCIATED HAZARDS. TEMPERATURES AND WINDS WERE ADJUSTED SLIGHTLY DURING ALL PERIODS. DEWPOINTS WERE SIGNIFICANTLY INCREASED FROM PREVIOUS PACKAGE FOR SUNDAY/SUNDAY NIGHT TIMEFRAME. MADE ONLY MINOR CHANGES TO MONDAY AND BEYOND. BLAIR && .AVIATION... BKN AC WITHIN THE WAA PATTERN ACROSS CENTRAL KS COMING IN AROUND 8 KFT. DO NOT ANTICIPATE CIGS LOWERING WHILE WEAK SFC RIDGING AND RELATIVELY DRY BOUNDARY LAYER AIR PERSISTS INTO NORTHEAST KS. ISENTROPIC UPGLIDE AND MOISTURE ADVECTION HAS TRIGGERED ISOLATED SHRA OVER NORTH CENTRAL KS. WITH RUC AND NAM ISENTROPIC CHARTS INDICATING RATHER SMALL AREAS OF LIFT...EXPECT PRECIP TO REMAIN ISOLATED GIVEN A LACK OF LARGE SCALE FORCING. KMHK MAY BE THE ONE SITE TO MONITOR FOR PRECIP. MAIN IMPACT WOULD BE BRIEF MVFR VSBY. WAA PATTERN WILL CONTINUE TONIGHT INTO EARLY SATURDAY MORNING. ANTICIPATE ELEVATED CONVECTION TO BE MORE WIDESPREAD AFT 00Z SAT DUE TO STRONGER LLJ AND BETTER ISENTROPIC LIFT. WOLTERS && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 933 PM EDT SAT OCT 13 2007 .SHORT TERM.../THE REST OF TONIGHT/...UPDATED MID AND HIGH CLOUDS WERE INCREASING ACROSS EASTERN KENTUCKY. THE LATEST RUC SHOWS MID LEVEL MOISTURE INCREASING AND LINGERING THROUGH THE NIGHT...ESPECIALLY IN THE NORTHERN PORTION OF OUR CWA. INCREASED CLOUD COVER TO GO WITH MOSTLY CLOUDY SKIES IN THIS AREA. MODELS ALSO SHOW A WEAKENING H5 WAVE MOVING THROUGH OVERNIGHT. NOT EXPECTING THIS TO PRODUCE ANY PRECIP THOUGH. ALSO INCREASED SKY COVER AMOUNTS ELSEWHERE TO GO WITH A PARTLY CLOUDY FORECAST. DID NOT CHANGE TEMPERATURES MUCH...EVEN WITH INCREASED CLOUD COVER. ATTM...MOSTLY CLEAR SKIES HAVE ALLOWED VALLEY TEMPERATURES TO BEGIN TO PLUNGE. AS THE CLOUDS MOVE IN...THIS SHOULD SLOW THE TEMPERATURE DROP...HOWEVER THE PREVIOUS FORECAST LOWS SHOULD BE ABLE TO BE REACHED WITH THE HELP OF THE INITIAL TEMPERATURE DROP. ONLY MADE SOME MINOR TWEAKS TO TEMPERATURES OVERNIGHT. UPDATED TEXT...DIGITAL AND GRAPHICAL PRODUCTS WILL BE OUT SOON. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TONIGHT THROUGH SUNDAY NIGHT/ HIGH PRESSURE OVER THE OHIO VALLEY WILL SLIDE EAST ON SUNDAY...WITH UPPER RIDGING BUILDING INTO OUR AREA. THE CHALLENGE IN THE SHORT TERM IS THE AMOUNT OF CLOUDINESS TONIGHT AND EFFECT ON OVERNIGHT LOW TEMPERATURES. MODEL TIME HEIGHTS INDICATE AN INCREASE IN HIGH LEVEL CLOUD...CI/CS ACROSS THE AREA TONIGHT...AND ALSO SOME MID LEVEL CLOUD ESPECIALLY IN THE NORTH. SATELLITE TRENDS SHOW CLOUD STREAMING EAST FROM AREA OF CONVECTION OVER MISSOURI...BUT ALSO SHOW CLOUD ERODING AS IT MOVES EAST. VARIOUS MOS GUIDANCE SHOWING DIFFERENCES IN SKY COVER WITH OLD FWC SHOWING OVC AT JKL...LOZ AND 5I3 BY 12Z SUNDAY. HOWEVER THIS IS OUTLIER WITH OTHER GUIDANCE SHOWING SCT TO CLEAR. BASED ON CURRENT TRENDS....AND GFS AND WRF MODEL GUIDANCE HAVE FOLLOWED IDEA OF SOME INCREASE IN CLOUDS TONIGHT. BUT ALSO EXPECT CLOUDS TO REMAIN MAINLY SCATTERED AT BEST...ALTHOUGH SOME BKN BUT THIN CS/CI MAY OCCUR. WITH SKIES BEGINNING AS CLEAR THIS EVENING...DEWPOINTS MAINLY IN THE LOWER 40S TO UPPER 30S...AND MAINLY HIGH CLOUDS TONIGHT...EXPECT ABOUT A 10 DEGREE RIDGE VALLEY TEMPERATURE SPLIT TO DEVELOP. THE SLIGHT INCREASE IN CLOUDS TONIGHT SHOULD PREVENT TEMPERATURES FROM GETTING AS COLD AS THIS MORNING. WE HAD A COUPLE OF COOP REPORTS OF 32 THIS MORNING AND A 31 FROM A WEATHER SPOTTER. EXPECT COLDEST READINGS TO BE IN THE UPPER 30S OVERNIGHT...BUT THERMAL BELT RIDGES IN THE UPPER 40S. THE MAVMOS SEEMS TO BE HANDLING THIS TEMPERATURE SPLIT THE BEST...AND HAVE FOLLOWED CLOSELY FOR OVERNIGHT LOWS. ON SUNDAY WARM AIR ADVECTION CONTINUES AND LOOK FOR HIGH TEMPERATURES TO BE IN THE 70S. MAVMOS LOOKS A LITTLE TOO HIGH IN THE EAST BASED ON ITS PERFORMANCE TODAY...BUT SHOULD BE GOOD IN THE SOUTHWEST PART OF THE FORECAST AREA. WARM UP CONTINUES WITH LOWS SUNDAY NIGHT SEVERAL DEGREES WARMER THAN THOSE EXPECTED TONIGHT. .LONG TERM.../MONDAY THROUGH SATURDAY/ ALL MODEL SOLUTIONS DIFFER GREATLY IN THEIR HANDLING OF NEXT WEEKS WEATHER. DGEX AND GFS ARE MUCH SLOWER AND NOT NEARLY AS WET AS ECMWF RUN. BOTH GFS AND DGEX FORM A VERY STRONG AREA OF LOW PRESSURE IN THE CENTRAL PLAINS FOR NEXT SATURDAY NIGHT AND SUNDAY IN THE 6Z RUN. THE GFS BACKED OFF ON THIS FEATURE IN THE 12Z RUN DRAMATICALLY. WITH SO MUCH UNCERTAINTY IN THE MODELS IN REGARDS TO WEATHER FOR THE END OF NEXT WEEK...WENT PRIMARILY WITH THE GFS SOLUTION...WITH SOME TWEAKS MADE BASED ON THE 6Z DGEX SOLUTION. INCREASED PRECIP CHANCES OVERALL FOR NEXT THURSDAY AND FRIDAY. KEPT PRECIP OUT OF THE FORECAST FOR NOW NEXT SATURDAY CONSIDERING THE DRASTIC DIFFERENCES AMONGST THE DIFFERENT MODELS. CONTINUED TREND OF COOLER THAN MEXMOS DAYTIME HIGH TEMPERATURES...TAKING INTO ACCOUNT THE AMOUNT OF CLOUD COVER ANTICIPATED WED-SAT OF NEXT WEEK AND THE INCREASED CHANCES OF PRECIPITATION. WINDS WERE TWEAKED SLIGHTLY TO REFLECT CHANGES MADE TO FRONTAL PASSAGES NEXT WEEK. SKY COVER FORECAST WAS QUITE A CHALLENGE WITH THE MODELS ALL COMING WITH VERY DIFFERENT SOLUTIONS...SO WENT WITH PARTLY TO MOSTLY CLOUDY SKIES EACH DAY NEXT WEEK...WITH THE BEST COVERAGE OF LOW AND MIDDLE CLOUDS FORECAST FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT AS AN AREA OF LOW PRESSURE MOVES OUT OF THE PLAINS. DEWPOINTS WERE ALREADY IN GOOD SHAPE AND ONLY SMALL CHANGES WERE MADE THERE. KEPT IN MENTION OF THUNDERSTORMS FOR TUESDAY AFTERNOON AND EVENING...AS IT APPEARS THERE WILL BE JUST ENOUGH INSTABILITY PRESENT TO PERHAPS SPARK AN ISOLATED STORM OR TWO. GFS ALSO SHOWING A PERSISTENT AND FAIRLY STRONG 850 HPA JET DURING THE DAY TUESDAY...THIS FEATURE HAS BEEN CONSISTENT IN THE MODEL DATA FOR 3 DAYS NOW...WHICH IS SUPPORTED BY 70-80KT UPPER LEVEL JET CORES. THESE UPPER LEVEL DIVERGENCE ASSOCIATED WITH THESE JET FEATURES WILL ALSO LEND SUPPORT TO ISOLATED THUNDERSTORMS ON TUESDAY BY INCREASING UPWARD VERTICAL MOTION IN THE LOW AND MIDDLE LEVELS OF THE ATMOSPHERE. WENT WITH FAIRLY LIGHT RAINFALL AMOUNTS ACROSS THE BOARD...WITH THE BEST AREAL COVERAGE ON TUESDAY AND WEDNESDAY. SOME LINGERING SHOWERS WILL BE POSSIBLE WEDNESDAY AND THURSDAY IN MOIST NORTHWEST FLOW...IN THE HIGHER TERRAIN ALONG THE VIRGINIA AND WEST VIRGINIA BORDERS...SO A CHANCE OF RAIN WAS INCLUDED IN THE FORECAST FOR THOSE TWO DAYS AS WELL. && .AVIATION.../00Z TO 24Z/ VFR CONDITIONS ARE EXPECTED AT THE TAF SITES THROUGH THE PERIOD. AN AREA OF MID AND HIGH CLOUDS WAS APPROACHING FROM THE WEST. THESE SHOULD BECOME BROKEN OVER EASTERN KENTUCKY LATER THIS EVENING. SCT TO BKN MID AND HIGH CLOUDS SHOULD CONTINUE INTO SUNDAY...BEFORE DECREASING LATER IN THE AFTERNOON. WILL GENERALLY GO WITH BKN120 IN THE TAFS THROUGH THE PERIOD FOR THE AVERAGE SKY COVER...ALTHOUGH THERE WILL LIKELY BE SOME PERIODS OF SCT120...WITH CI ABOVE...ESPECIALLY SUNDAY AFTERNOON. NO FOG EXPECTED AT THE TAF SITES...HOWEVER SOME LOCALIZED IFR FOG IS POSSIBLE JUST IN THE RIVER VALLEYS. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...SBH/WJM LONG TERM....AR AVIATION...WJM ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 115 AM EDT FRI OCT 12 2007 .AVIATION (06Z TAFS)... LIGHT NORTHERLY FLOW WILL CONTINUE TONIGHT AND TOMORROW. MOISTURE TRAPPED UNDER A SUBSIDENCE INVERSION HAS PROMOTED AN EXTENSIVE BUT THIN CEILING OF STRATO-CU AROUND 5K FT. EXPECT CLOUDS WILL REMAIN THROUGH 14Z AT LEX AND SDF...WITH ONLY AN OCCASIONAL AND TEMPORARY CLEAR AREA PASSING BY. AT BWG...SKIES MAY PARTIALLY CLEAR AROUND 12Z. CLOUD COVER WILL CONTINUE THROUGH MUCH OF TOMORROW AT LEX...BUT MAY GO SCATTERED AT SDF AND BWG BY MID MORNING. CEILINGS LATER TODAY WILL REMAIN VFR AT GREATER THAN 3 THOUSAND FEET. NO RESTRICTIONS TO VISIBILITY ARE EXPECTED. WINDS WILL CONTINUE FROM THE NORTH LATER TODAY...BUT WILL BE LIGHTER THAN IN PAST DAYS...RANGING FROM 5 TO 10 MPH THIS UPCOMING AFTERNOON. JSD .SHORT TERM UPDATE:... LOOKING AT THE OVERNIGHT LOW LEVEL RH TRENDS FROM THE RUC AND IR SAT PICS FOR UPSTREAM CLOUDS AND CLOUD TRENDS...WILL HAVE TO GO WITH MOSTLY CLOUDY SKIES UNTIL PERHAPS THE LATE NIGHT HOURS...AND THEN ONLY WITH SOME LATE NIGHT CLEARING ACROSS THE SWRN THIRD OF FA WHILE REMAINING PARTLY TO MOSTLY CLOUDY ELSEWHERE TONIGHT. WILL UP TEMPS A FEW DEGREES ACROSS THE NERN TWO THIRDS OF FA BECAUSE OF THE INCREASED CLOUD COVER. FCST TRENDS BEYOND TONIGHT LOOK OK AT THIS TIME. --21 && && .SHORT TERM (TONIGHT AND FRIDAY)... A BROAD NORTHWEST FLOW WILL CONTINUE ACROSS THE LOWER OHIO VALLEY ALTHOUGH THE COLDEST AIR HAS MOVED THROUGH THE REGION. THIS COMBINED WITH SLIGHTLY HIGHER DEW POINTS VALUES SHOULD KEEP LOW TEMPERATURES TONIGHT SEVERAL DEGREES WARMER THAN THURSDAY MORNING. THE OTHER CONCERN WILL BE CLOUD COVER. WE EXPECT MOST AREAS TO CLEAR TONIGHT WITH THE EXCEPTION OF THE NORTHEAST WHERE THICKER CLOUDS WILL BE HARDER TO DISSIPATE. THE UPPER CLOSED LOW WILL REMAIN STALLED OVER THE UPPER GREAT LAKES SO FRIDAY WILL BE SIMILAR TO TODAY. TEMPERATURES MAY BE A FEW DEGREES WARMER THAN TODAY BUT A SPOKE MOVING AROUND THE CLOSED LOW WILL DROP INTO THE REGION AND KEEP SKIES PARTLY TO MOSTLY CLOUDY. JA .LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... .FRIDAY NIGHT-MONDAY NIGHT... BY FRIDAY NIGHT...GREAT LAKES UPPER LOW FINALLY MOVES TOWARD NEW ENGLAND...RELAXING OUR NW FLOW A BIT AS A DEEP TROUGH SETS UP OVER THE 4-CORNERS REGION. CANADIAN HIGH PRESSURE AND RIDGING OVER THE PLAINS WILL SETTLE IN OVER OUR REGION FOR THE WEEKEND. THIS RIDGING WILL ALLOW TEMPS TO INCREASE THROUGH MONDAY AS THE 1000-850MB THICKNESSES STEADILY RISE. ABOVE-AVERAGE TEMPS SHOULD BE THE RULE SUNDAY...WHERE HIGHS SHOULD BE IN THE MID 70S. SHOULD BE A PRISTINE WEEKEND FOR OUTDOOR ACTIVITIES. BY MONDAY...MODELS (GFS AND ECMWF) SEEM TO HAVE DIFFERENT SOLUTIONS WITH THE 4-CORNERS LOW. ECMWF AMPLIFIES THE RIDGE OVERHEAD...MAKING THE LOW FIZZLE AS IT APPROACHES THE REGION. THE GFS DOES NOT AMPLIFY THE RIDGE AS MUCH...AND DEEPENS THE LOW MORE...TAKING IT TOWARD THE CWA. EITHER WAY...THE UPPER LOW SHOULD PRODUCE A SFC LOW EAST OF THE ROCKIES ON MONDAY...WHERE WARM-AIR ADVECTION PRECIP WILL OCCUR OVER THE PLAINS. THIS PRECIP SHOULD STAY WELL WEST OF THE AREA...MAINLY AFFECTING SUCH STATES AS THE HAWKEYE STATE...THE SHOW ME STATE ...AND THE LAND OF LINCOLN. BUT OVER OUR AREA...WE WILL HAVE A GOOD SWLY FLOW...HELPING TEMPS REBOUND TO NEAR THE 80 DEGREE MARK. AL TUESDAY-THURSDAY... BY TUESDAY...MOISTURE INCREASES AHEAD OF THE PLAINS` LOW. THE HERCULEAN EAST COAST RIDGE WILL UNDOUBTEDLY SLOW THE PROGRESS OF THE FRONT...SO HAVE KEPT THE CHC POPS TIL AFTER 12Z TUE. AS MENTIONED ABOVE THE GFS IS MUCH MORE AGGRESSIVE AND QUICKER WHICH SEEMS UNLIKELY WITH A 589M HIGH OFF EAST COAST. OTHER MODELS LIKE DGEX AND ECMWF ARE MUCH WEAKER WITH THIS FEATURE AND HAVE LESS QPF OVER CWA. EVEN IF THE GFS IS CORRECT...WE WILL NOT GET THAT MUCH QPF WITH THIS EVENT...AND FOLLOWED HPC LEAD ON DAYS 5-7. EAST COAST RIDGE AMPLIFIES ONCE AGAIN WITH DEEP PLAINS TROUGH AND MOST OF THE ENERGY BEING DISPLACED NE TOWARDS THE UPPER MS RIVER VALLEY. BOTTOM LINE...THE DROUGHT CONTINUES IN EARNEST! JDG && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 958 AM CDT SAT OCT 13 2007 .UPDATE...AN EARLY RETURN FLOW HELD TEMPS TO AROUND 60 THIS MORNING IN THE BEAUMONT AREA. OTHERWISE THE SURFACE RIDGE CONTINUES TO HOLD OVER THE AREA THUS PROVIDING CLEAR SKIES AND CHAMBER OF COMMERCE LOWER HUMIDITIES UNDER A LIGHT EAST TO SOUTHEAST FLOW. ONLY A FEW TWEAKS TO LOWER AFTERNOON TEMPS FOR INTERIOR ZONES BASED ON LATEST FIRST GUESS GFS AND CURRENT RUC. ALSO ADJUSTED TNITE`S MIN TEMP FOR BPT UPWARD BASED ON CURRENT TRENDS (RETURN FLOW ALREADY IN PROGRESS THERE). && .PREV DISCUSSION... /ISSUED 506 AM CDT SAT OCT 13 2007/ ..CLEAR SKIES AND MILD TEMPERATURES THROUGH THE WEEKEND... SHORT/LONG TERM... NOT MUCH TO SAY...MILD TEMPERATURES BEHIND THE FRONT WITH HIGHS TODAY AND TOMORROW REACHING THE LOW 80S WITH LIGHT WINDS. GREAT DAY FOR OUTDOOR ACTIVITIES SUCH AS THE STATE FAIR GOING ON IN SOUTHEAST TEXAS ALONG WITH GOLFING...HIKING...AND FISHING. THIS WEATHER PATTERN WILL CONTINUE INTO EARLY TUESDAY BEFORE AN UPPER LEVEL LOW MOVES INTO THE CENTRAL US. THE LOW WILL TRAIL A COLD FRONT IN IT`S WAKE WHICH IS EXPECTED TO STALL OVER THE COASTAL WATERS EARLY WEDNESDAY MORNING BEFORE WASHING OUT. THIS WILL MEAN A CHANCE FOR SOME SHOWERS ON TUESDAY INTO WEDNESDAY. && .PRELIMINARY POINT TEMPS/POPS... KLCH 82 59 82 67 / 0 0 0 0 KBPT 83 62 82 69 / 0 0 0 0 KAEX 81 55 83 60 / 0 0 0 0 KLFT 82 57 82 65 / 0 0 0 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$ 11 la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 1032 AM CDT FRI OCT 12 2007 .UPDATE...DRY CONTINENTAL POLAR AIR OVER THE AREA WITH HIGH PRESSURE RIDGING IN FROM ONTARIO TO NORTHEAST MEXICO. LATEST RUC AND OBS SHOW DRIER AND COOLER AIR THAN PREVIOUS GUIDANCE. WILL TWEAK TEMPS DOWN THIS AFTERNOON AND INTO TNITE. && .PREV DISCUSSION... /ISSUED 352 AM CDT FRI OCT 12 2007/ SHORT/LONG TERM... MILD WEATHER EXTENDS FROM THE UPPER PLAINS STATES DOWN INTO THE SOUTHERN STATES AS A SURFACE LOW EXITS THE NEW ENGLAND STATES THIS AM. IR IS SHOWING THE FRONTAL BOUNDARY DRAPED OVER THE CENTRAL GULF WITH A FEW CLOUDS ALONG THE BOUNDARY. IN ADDITION ANOTHER FRONT IS CURRENTLY SPILLING DOWN INTO THE REGION...BUT THIS WILL ONLY CONTINUE THE SUNNY SKIES AND MILD TEMPERATURES OVER THE WEEKEND WHICH WILL BE GREAT WEATHER FOR THE SOUTHEAST TEXAS STATE FAIR. THE WEATHER WILL BE PERFECT FOR THE FOOTBALL GAMES FOR FRIDAY NIGHT AND ON SATURDAY AND WITH A ROUND OR TWO OF GOLF. THE ATMOSPHERE WILL REMAIN DRY UNTIL MONDAY... AT THAT TIME AN UPPER LEVEL TROF WILL SWING DOWN INTO THE REGION AND THIS WILL BRING ANOTHER FRONT AND ANOTHER CHANCE FOR SOME RAIN TO THE REGION ON TUESDAY. AVIATION... CLEAR SKIES AND 10 MILES VSBY THROUGH THE DAY INTO TONIGHT AS HIGH PRESSURE REMAINS IN PLACE. && .PRELIMINARY POINT TEMPS/POPS... KLCH 82 55 85 62 / 0 0 0 0 KBPT 84 57 85 62 / 0 0 0 0 KAEX 80 48 84 55 / 0 0 0 0 KLFT 80 54 84 59 / 0 0 0 0 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$ la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1255 PM EDT SAT OCT 13 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR TROF OVER SE CAN WITH VORTEX CENTERED JUST S OF JAMES BAY. SHRTWV NOTED ON NRN FLANK OF THIS FEATURE AND DRIFTING WWD...BUT MSTR ON THE WRN FLANK OF THIS CUTOFF IS MAKING ONLY SLOW PROGRESS WWD. AT 03Z ON SAT...WRN EDGE OF MSTR/CLD COVER WAS FM THE E END OF LK NIPIGON TO ERY. BUT MSTR GRADIENT IS VERY SHARP...SO MOST OF THE FA IS CLR AND CHILLY WITH LGT WINDS UNDER SFC RDG AXIS EXTENDING FM YPL INTO WRN LK SUP AND CNTRL WI. 00Z RAOB FM YPL AND REPRESENTATIVE OF THE AIRMASS UNDER THE RDG IS QUITE DRY WITH PWAT 0.28 INCH. OTRW...MORE CLD NOTED OVER W AND CNTRL MN...BUT THIS CLD IS MAKING LTL IF ANY EWD PROGRESS INTO RDG/DRY AIRMASS HELD IN PLACE BY CUTOFF LO IN ONTARIO. POTENT SHRTWV DROPPING INTO SRN CA IS DEEPENING TROF OVER THE DESERT SW. MAIN FCST CONCERNS THIS PACKAGE INCLUDE SHRA CHCS OVER THE E TDAY ACCOMPANYING DEEP MSTR ON WRN FLANK OF ONTARIO CUTOFF LO AND THEN ACRS THE SCNTRL CWA BEGINNING LATE SUN ASSOCIATED WITH SHRTWVS TRYING TO LIFT NEWD OUT OF TROF DEEPENING IN THE DESERT SW AND DROPPING SEWD FM SCNTRL CAN. FOR TDAY...LATEST NAM/GFS IN FAIRLY GOOD AGREEMENT SHOWING SHRTWV NOW ROTATING ARND NRN FLANK OF CUTOFF LO OVER ONTARIO SWINGING SWD ON THE WRN FLANK OF THIS FEATURE THIS MRNG BUT E OF ANJ. BOTH MODELS SUG MSTR WL REMAIN E OF P53 OR SO WITH SOME LGT PCPN BRUSHING LUCE COUNTY BEFORE HGTS BEGIN TO RISE LATE IN THE DAY ONCE SHRTWV MOVES TO THE E AND BEGINS TO DRAG CUTOFF EWD AS WELL IN THE AFTN. CONSIDERING DRYNESS OF AIRMASS TO THE W...WL MAINTAIN NOTHING MORE THAN A 30 POP OVER THE FAR E IN AREA WHERE NAM/GFS SHOW SOME DPVA/ H85-5 QVECTOR CNVGC THIS MRNG ASSOCIATED WITH SHRTWV PASSING TO THE OF ANJ AS WELL AS CYC NW FLOW OF CHILLY AIR (H85 TEMPS AS LO AS -2C) INTO THE AFTN. OTRW...MIXING TO ABOUT H85 ON NAM FCST SDNGS FOR TDAY YIELDS HI TEMPS INTO THE MID 50S WHERE THERE WL BE MORE SUNSHINE OVER THE SCNTRL AND LLVL NW FLOW WL BE DOWNSLOPING. TEMPS WL BE A BIT COOLER OVER THE CLOUDIER E. EXPECT A MOCLR AND CHILLY NGT TNGT OVER THE W AND CNTRL WITH HI PRES RDG/AXIS OF PWAT AS LO AS 0.25 INCH DOMINATING. ALTHOUGH THE ERN ZNS LOOK TO DRY OUT AS WELL...CONCERNED A STEADIER NNW FLOW IN THE PRES GRADIENT BTWN RDG AXIS OVER WRN LK SUP AND SLOWLY DEPARTING LO TO THE E WL LIMIT DIURNAL TEMP FALL THERE. WL TEND AOB THE LO END OF MOS GUIDANCE OVER THE INTERIOR W AND CTNRL BUT NEAR GUIDANCE OVER THE E. FOCUS ON SUN SHIFTS TO THE SW AND THE NW. TROF OVER THE DESERT SW THIS MRNG PROGGED TO LIFT OUT INTO THE SCNTRL PLAINS BY 00Z MON WHILE ANOTHER SYS RIPPLING SEWD IN NRN BRANCH WNW FLOW ALF LEFT IN WAKE OF DEPARTING CUTOFF LO TO THE E APRCHS AS WELL. COMPLEX INTERACTION BTWN BRANCHES IS ALWAYS A DIFFICULT ISSUE...BUT 00Z GUIDANCE SEEMS AT LEAST CLOSE ON MANY OF THE DETAILS. GFS IS A BIT MORE AGGRESSIVE AT GENERATING SOME LGT PCPN OVER THE WI BORDER ZNS BEFORE 00Z MON...BUT MODEL FCST SDNGS SHOW A SFC-H8 DRY LYR THRU 00Z EVEN AT IMT/MNM MAINTAINED BY LLVL NE FLOW OUT OF CORE OF DRY AIRMASS CENTERED JUST E OF LK SUP. THUS OPTED TO MAINTAIN GOING DRY FCST FOR THE ENTIRE DAY MORE IN LINE WITH 00Z UKMET/NAM...ESPECIALLY SINCE PLAINS TROF REMAINS POSITIVELY TILTED THRU THE DAY. GFS IS THEN MOST AGGRESSIVE AT DRYING OUT THE FA SUN NGT FOLLOWING PASSAGE OF MORE ROBUST SHRTWV EMBEDDED IN THE NRN BRANCH...THE RESULT OF WHICH IS TO KEEP THE MSTR ASSOCIATED WITH THE PLAINS TROF SHUNTED TO THE S. THE NAM ON THE OTHER HAND TENDS TO PHASE THE BRANCHES MORE TO THE W OF THE UPR LKS...RESULTING IN A MORE SW FLOW ALF AND A CLOUDIER...SHOWERY TIME. PER NCEP MANUAL GUIDANCE...WL FOLLOW A 00Z GFS/12Z ECMWF BLEND...WHICH SEEMS WELL REPRESENTED BY 00Z UKMET. THE UKMET SHOWS A SLOWER PROGRESSION OF THE NRN BRANCH SHRTWV...WHICH ALLOWS DEEPER MSTR/CLD COVER TO LINGER LONGER OVER THE SCNTRL AND E SUN NGT AND INTO MON BEFORE DRYING OVERSPREADS THE AREA LATER ON MON IN WAKE OF NRN BRANCH SHRTWV PASSAGE. LOWERED FCST MIN TEMPS ON MON NGT WITH EXPECTATION OF COOL DRY AIRMASS SPREADING INTO THE UPR LKS BEHIND NRN BRANCH SHRTWV PASSAGE. CONSIDERING WIDE RANGE OF FCST SCENARIOS AFT MON NGT IN REGARDS TO SRN BRANCH TROF/MSTR FCSTS OVER THE UPR LKS...CHOSE NOT TO MAKE ANY CHGS AFT MON NGT. COORDINATED WITH DLH/GRB/LOT/APX. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... VFR CONDITIONS SHOULD PREVAIL AT KCMX/KSAW THRU THIS FCST PERIOD WITH SFC HIGH PRESSURE IN CONTROL. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NORTHWEST WINDS OF 15 TO 30 KNOTS OVER EASTERN LAKE SUPERIOR WILL GRADUALLY DIMINISH TODAY AND TONIGHT AS LOW PRESSURE OVER EASTERN ONTARIO SHIFTS INTO QUEBEC AND HIGH PRESSURE FROM WRN ONTARIO INTO THE UPPER MISSISSIPPI VALLEY BUILDS INTO THE WESTERN GREAT LAKES. WINDS WILL BECOME EAST TO NORTHEAST AND STRENGTHEN TUESDAY AS HIGH PRESSURE STRENGTHENS OVER NORTHERN ONTARIO AND AND LOW PRESSURE MOVES FROM THE PLAINS TO ILLINOIS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KC AVIATION...MICHELS MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 105 AM EDT SAT OCT 13 2007 .AVIATION...VFR CONDITIONS EXPECTED THROUGH SATURDAY NIGHT WITH SOME LAKE/DIURNALLY INDUCED CU/SC EXPECTED. PRECIPITATION IS NOT ANTICIPATED AT THE TERMINAL SITES AT THIS POINT. JPB && .UPDATE... /ISSUED 1023 PM EDT FRI OCT 12 2007/ SCATTERED LAKE INDUCED RAIN SHOWERS CONTINUE TO DRIFT IN OFF OF LAKE MICHIGAN THIS EVENING...PRECIPITATION RECEIVED A BOOST IN COVERAGE FOR A WHILE AS REMAINING DIURNALLY DRIVEN CU MOVED OFF OF CENTRAL UPPER MI AND ONTO THE LAKE...WHICH IS A COMMON EVOLUTION. NOW THAT THE UPSTREAM CLOUD COVER HAS DISSIPATED...SHOWER COVERAGE HAS BEGUN TO WANE. 00Z APX SOUNDING PEGGED THE INVERSION RIGHT AROUND 800MB/-5C...WITH AIRCRAFT SOUNDINGS IMPLYING INVERSION HEIGHTS AROUND 850MB ACROSS EASTERN UPPER WHERE PRECIPITATION HAS BEEN NON-EXISTENT THUS FAR. MEANWHILE...UPPER LOW ALONG ONTARIO/QUEBEC BORDER BEGINNING TO DRIFT SOUTH...WRAPPING SOME DEEPER MOISTURE AROUND ITS WESTERN/SOUTHERN FLANKS AND INTO EASTERN LAKE SUPERIOR. ONTARIO RADAR COMPOSITE SHOWING A BROAD AREA OF REFLECTIVITY WRAPPING TOWARD EASTERN LAKE SUPERIOR...SOME OF THIS NOW SHOWING UP ON THE KAPX 88D DRIFTING SOUTH ACROSS THE NORTH CHANNEL TOWARD MANITOULIN ISLAND. HAVEN`T SEEN ANY PRECIP REPORTS OUT OF WAWA OR SOO ONTARIO WITH THIS...DOES APPEAR TO BE A NARROW LAKE ENHANCED BAND DRIFTING IN OFF LAKE SUPERIOR. THERE IS ALSO AN EAST-WEST ORIENTED CONVERGENCE BAND EXTENDING OUT INTO LAKE HURON FROM JUST EAST OF THE STRAITS...WHICH HAS ALSO BEEN THE FOCUS FOR SOME RADAR RETURNS OFF PRESQUE ISLE LIGHT. PRECIPITATION PROBLEMS FOR THE OVERNIGHT WILL MOST LIKELY BE CONFINED TO EASTERN UPPER. GENERAL SUBSIDENCE OVER MUCH OF NORTHERN LOWER MI SHOULD GRADUALLY PUSH INVERSION HEIGHTS DOWNWARD OVERNIGHT. SO EXPECT RAIN SHOWERS OVER NORTHWEST LOWER TO WIND DOWN AFTER MIDNIGHT. ACROSS EASTERN UPPER DEEPER MOISTURE WILL ROTATE IN FROM THE NORTH OVERNIGHT. SOME WEAK QG FORCING WITH THIS DRIVEN MOSTLY BY THERMAL ADVECTION...THOUGH SOME LOW/MID LEVEL FRONTOGENESIS/FRONTOLYSIS COUPLING HELPING OUT AS WELL. INCREASED MOISTURE...WEAK FORCING...AND SOME CONTRIBUTION OFF LAKE SUPERIOR (POSSIBLY AIDED BY INCREASING LOW LEVEL CONVERGENCE ALONG INVERTED TROUGH DRIFTING SOUTH ACROSS LAKE SUPERIOR) WILL INCREASE THE THREAT FOR SHOWERS ACROSS MUCH OF EASTERN UPPER AFTER 06Z. SOME OF THIS MAY JUST GRAZE FAR NORTHEAST LOWER DURING THE EARLY MORNING HOURS AS WELL. MEANWHILE...EXPECT AREAS EAST OF A CAD-APN LINE WILL BE PARTLY CLOUDY FOR THE MOST PART OVERNIGHT. JPB PREV DISCUSSION... /ISSUED 334 PM EDT FRI OCT 12 2007/ A MYRIAD OF FORECAST CONCERNS HEADING INTO TONIGHT AND SATURDAY... NAMELY LAKE EFFECT PRECIP...CLOUD COVER...AND TEMPERATURES. EARLY AFTERNOON ANALYSIS SHOWS A RATHER CONVOLUTED UPPER PATTERN...WITH A POTENT BUT RAPIDLY OCCLUDING UPPER LOW ACROSS SOUTHEASTERN ONTARIO...AND ANOTHER PIECE OF ENERGY RIDING UP THE NORTHEAST COASTLINE (WHICH MODELS PROG TO PHASE WITH EXISTING ENERGY OVER EASTERN CANADA). THIS HAS LEFT ALL OF NORTHERN MICHIGAN IN PRONOUNCED CYCLONIC FLOW ALOFT...WITH CHANNELED VORT LOBE DROPPING THROUGH THE REGION EARLY THIS AFTERNOON WORKING IN TANDEM WITH SUFFICIENT LOW LEVEL MOISTURE (RUC 900-800MB MOISTURE IN EXCESS OF 75%) AND OVER LAKE DELTA T/S ON THE ORDER OF 15C OR BETTER TO PRODUCE A SMATTERING OF LAKE EFFECT/ENHANCED RAIN SHOWERS FOR NORTHWEST FLOW AREAS. ENERGY TRANSLATING THROUGH THE REGION HAS EVEN BEEN SUFFICIENT TO ALLOW SHOWERS TO PROGRESS MUCH FARTHER INLAND THAN TYPICALLY EXPECTED...THOUGH THIS APPEARS TO BE PARTIALLY DRIVEN BY AFTERNOON LOW LEVEL INSTABILITY. FOR TONIGHT...THE BIGGEST QUESTION REMAINS COVERAGE OF LAKE EFFECT PRECIPITATION/CLOUDS AS OVERALL CYCLONIC/NORTHWESTERLY FLOW PATTERN REMAINS INTACT. WITH ONLY SOME MINOR WARM LOW LEVEL WARMING TAKING SHAPE (H85 TEMPS RISE TO AROUND 0C BY 12Z)... OVER LAKE INSTABILITY REMAINS GOOD WITH DELTA T/S BETTER THAN 13C. IN ADDITION...LOSS OF OVER-LAND MIXING WILL CERTAINLY AID IN RESTRUCTURING SOME BANDS OF PRECIP AFTER SUNSET. HOWEVER...A PEAK UPSTREAM REVEALS LOW LEVEL DRYING MAKING PROGRESS TOWARD WESTERN LAKE SUPERIOR IN RESPONSE TO INCREASING SUBSIDENCE ON THE BACKSIDE OF ONTARIO CLOSED LOW. 12Z GFS APPEARS TO HAVE A GOOD HANDLE ON THIS OCCURRENCE...WITH FORECAST TIME HEIGHTS/RAOBS INDICATING THIS DRYING (950-800MB RH DROPS TO LESS THAN 40%) SLIPPING INTO NORTHERN LOWER MICHIGAN OVERNIGHT. THUS...WHILE DO EXPECT SOME LAKE EFFECT PRECIP TO CONTINUE INTO THE EARLY OVERNIGHT HOURS...APPEARS LOW LEVEL DRYING MAY BRING AN ABRUPT END AFTER MIDNIGHT ACROSS NORTHERN LOWER COUNTIES...WHILE EASTERN UPPER HANGS ONTO RESIDUAL SHOWERS IN BETTER MOISTURE ENVIRONMENT. IN ADDITION...WILL BE ON THE LOOKOUT FOR ADDITIONAL SHOWER CHANCES ACROSS MAINLY FAR NORTHEAST COUNTIES LATE TONIGHT INTO TOMORROW AS UPPER LOW FURTHER OCCLUDES AND GETS SHUNTED SOUTH...WITH INCREASING SUPPORT FOR ASCENT AS VORT MAX DROPS ACROSS LAKE HURON. APPEARS BEST 700-500MR -DIVQ WILL RESIDE JUST EAST OF THE REGION...THOUGH CERTAINLY CANNOT RULE OUT A FEW SHOWERS... PARTICULARLY WITH A BIT OF LAKE ENHANCEMENT ON NORTHWESTERLY FLOW. AS FOR CLOUD COVER/TEMPERATURES...CELLULAR NATURE OF CU/STRATOCU THIS AFTERNOON OVER THE SOUTHEAST CWA PORTENDS LIKELY RAPID CLEARING TOWARD SUNSET...WITH DOWNSLOPE FLOW/LOSS OF SYNOPTIC SUPPORT AIDING THIS PROCESS. ELSEWHERE...APPEARS LAKE DRIVEN STRATOCU LIKELY TO HOLD FOR A WHILE OVER NORTHWEST LOWER/EASTERN UPPER BEFORE AFOREMENTIONED LOW LEVEL DRYING KICKS IN ACROSS LAKE MICHIGAN OVERNIGHT. LATE TONIGHT INTO TOMORROW...THE BIG QUESTION REMAINS JUST HOW FAR WEST LOW LEVEL MOISTURE IN ASSOCIATION WITH DEEPLY OCCLUDED LOW TO THE EAST WILL WRAP. VARIOUS MODELS HAVE THEIR OWN SOLUTIONS REGARDING WESTWARD DEGREE OF RH INTO TOMORROW AFTERNOON...BUT A SUBJECTIVE ANALYSIS FROM LATE AFTERNOON VISIBLE SATELLITE/PLACEMENT OF UPPER LOW WOULD SUGGEST LOW/MID LEVEL MOISTURE WRAPPING BACK INTO EASTERN UPPER AND FAR NORTHERN LOWER LATE TONIGHT INTO MUCH OF TOMORROW. OBVIOUSLY...TEMPERATURES HIGHLY DEPENDENT ON DEGREE OF CLOUD COVER (REFERENCE THIS MORNING WITH COOLER THAN EXPECTED READINGS UNDER CLEARING SKIES). BEST GUESS FOR TONIGHT GIVEN ALREADY COOL READINGS THIS AFTERNOON IS UPPER 20S TO MID 30S AWAY FROM THE LAKE SHORES. HEADING INTO TOMORROW...TEMP FORECAST RATHER IFFY PENDING PLACEMENT OF CLOUD COVER...BUT WILL TREND THINGS UPWARD INTO THE LOW/MID 50S ACROSS THE SOUTH WHERE MORE SUNSHINE EXPECTED IN A DEEP LAYER DRY AIRMASS (900-300MB RH ONLY AROUND 30-40%)...BUT HOLD NUMBERS DOWN ACROSS THE NORTHEAST WHERE CLOUDS EXPECTED TO LINGER THROUGH MUCH OF THE DAY. MARINE SIDE OF THINGS...APPROACH OF VORT LOBE/SURFACE LOW OVERNIGHT APPEARS IT WILL TIGHTEN THE GRADIENT SUFFICIENT TO KICK UP WINDS ON AREA WATERS...CENTERED ON ABOUT 12Z WITH ISALLOBARIC COMPONENT GREATEST. WHILE SMALL CRAFT ADVISORY CONDITIONS NOT CURRENTLY BEING MET IN MOST SPOTS...ADVISORY CONDITIONS APPEAR LIKELY LATE TONIGHT INTO MIDDAY ON FRIDAY. WILL THEREFORE EXPAND SMALL CRAFTS THROUGH 18Z BEFORE GRADIENT AGAIN WEAKENS. EARLIER COMMENT ABOUT POTENTIAL GALES ON THE HURON SIDE APPEARS JUSTIFIED...BUT THIS EVENT LOOKS TO COME JUST A TAD SHORT WITH A MAXIMUM WIND OF ONLY 30 TO 35 KNOTS AT THE TOP OF THE MIXED LAYER. STILL SOMETHING TO BE WATCHED WITH COASTAL CONVERGENCE COMING INTO PLAY OVERNIGHT...BUT WILL HOLD OFF ON GALE ISSUANCE FOR NOW. LAWRENCE REMAINDER OF THE FORECAST...(SATURDAY NIGHT THROUGH NEXT FRIDAY)... LOTS OF QUESTIONS THROUGH THIS PERIOD AS THE EXTENDED MODELS ARE HAVING TROUBLE RESOLVING THE MOVEMENT OF THE CUTOFF UPPER LOW CURRENTLY EVIDENT ON WATER VAPOR LOOP SPINNING ITS WHEELS OVER THE NORTH CENTRAL CALIFORNIA COAST. THE MOVEMENT AND AFFECTS OF THIS FEATURE ON THE WESTERN GREAT LAKES WILL BE THE MAIN FOCUS OF THIS PORTION OF THE PACKAGE. SATURDAY NIGHT...RETROGRADING UPPER LOW TO OUR NORTHEAST WILL CONTINUE TO SINK SOUTH AND EVENTUALLY EASTWARD. THE NAM IS MUCH MORE BULLISH WITH THE SOUTHWEST PUSH OF LOW LEVEL MOISTURE. MEANWHILE...THE GFS/UKMET ARE IN AGREEMENT THAT THE DEEPER MOISTURE REMAINS CONFINED TO THE NORTHEASTERN FORECAST AREA AND THIS SCENARIO SEEMS PLAUSIBLE GIVEN CURRENT SATELLITE TRENDS. MEAN 900-700 MB RH SHOWS A LARGE RANGE FROM ONLY ABOUT 20 PERCENT SOUTHWEST TO BETWEEN 80 AND 90 PERCENT NORTHEAST AT 00Z SUN. THEREFORE...PARTLY CLOUDY TO MOSTLY CLEAR SKIES EXPECTED SOUTHWEST BUT REMAINING MOSTLY CLOUDY NORTHEAST. DEEPER MOISTURE ACROSS THE NORTHEAST SLOWLY DISSIPATES/MOVES NORTHEAST OVERNIGHT AS WELL. THERE WILL LIKELY BE A LARGE RANGE OF LOW TEMPERATURES AS WINDS ARE EXPECTED TO BE 10 KNOTS OR LESS. LOW RANGING FROM THE UPPER 20S INTERIOR SOUTHWEST TO THE UPPER 30S NORTHEAST (DUE TO THE ABUNDANT CLOUD COVER). SUNDAY...PESKY UPPER LOW CONTINUES TO SWIRL TO THE EAST AWAY FROM THE AREA. MEANWHILE...ATTENTION WILL TURN TO OUR SOUTHWEST AS ANOTHER UPPER LOW (IN THE SERIES) BEGINS TO TRACK NORTHEAST TOWARD THE WESTERN GREAT LAKES. MODEL SOUNDINGS/CROSS SECTIONS INCREASE MID AND UPPER LEVEL MOISTURE SUNDAY AFTERNOON BUT NOT BEFORE A GOOD DEAL OF SUNSHINE SUNDAY MORNING. HIGHS IN THE SEASONABLE MIDDLE 50S TO AROUND 60. SUNDAY NIGHT THOUGH NEXT WEDNESDAY...EXTENDED MODELS ALL BRING A DIFFERENT SPIN TO THE MOVEMENT/TIMING OF THE SOUTHWESTERN UPPER LOW. BLOCKING NO LONGER APPEARS TO BE STRONG ENOUGH TO HOLD THIS SYSTEM AT BAY. MODELS IN ONE FORM OR ANOTHER PROGRESS THIS FEATURE TOWARD THE WESTERN GREAT LAKES AND ACTUALLY STALL IT OUT (WHILE WEAKENING IT) OVER OR JUST TO THE SOUTH OF THE AREA. TO START THE BALL ROLLING...A BAND OF FRONTOGENESIS IS SHOWN TO OVERSPREAD THE REGION SUNDAY NIGHT INTO MONDAY LEADING TO CHANCE POPS ACROSS NORTHERN LOWER. THE UPPER LOW THEN GETS CLOSE ENOUGH ON TUESDAY AND POSSIBLY STALLS OUT OVER THE REGION BY WEDNESDAY SO WILL ADD POPS INTO THESE TIME PERIODS AS WELL. HIGHS GENERALLY IN THE MIDDLE 50S TO LOWER 60S WITH LOWS IN THE UPPER 30S TO LOWER 40S. THURSDAY AND FRIDAY...AFTER COLLABORATION WITH SURROUNDING OFFICES...WILL ASSUME THAT THE UPPER LOW HAS DISSIPATED/MOVED OFF TO OUR EAST ON THURSDAY (WHICH MAY BE A STRETCH). THIS WILL LEAD TO LEAVING THURSDAY DRY FOR NOW. YET ANOTHER UPPER LOW IN WHAT SEEMS LIKE AN ENDLESS PARADE THEN MARCHES TOWARD THE AREA SO WILL BRING IN MORE CHANCE POPS FOR FRIDAY. SIMILAR TEMPERATURES WITH HIGHS IN THE MIDDLE 50S TO AROUND 60 AND LOWS BETWEEN 40 AND 45. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1023 PM EDT FRI OCT 12 2007 .UPDATE...SCATTERED LAKE INDUCED RAIN SHOWERS CONTINUE TO DRIFT IN OFF OF LAKE MICHIGAN THIS EVENING...PRECIPITATION RECEIVED A BOOST IN COVERAGE FOR A WHILE AS REMAINING DIURNALLY DRIVEN CU MOVED OFF OF CENTRAL UPPER MI AND ONTO THE LAKE...WHICH IS A COMMON EVOLUTION. NOW THAT THE UPSTREAM CLOUD COVER HAS DISSIPATED... SHOWER COVERAGE HAS BEGUN TO WANE. 00Z APX SOUNDING PEGGED THE INVERSION RIGHT AROUND 800MB/-5C...WITH AIRCRAFT SOUNDINGS IMPLYING INVERSION HEIGHTS AROUND 850MB ACROSS EASTERN UPPER WHERE PRECIPITATION HAS BEEN NON-EXISTENT THUS FAR. MEANWHILE...UPPER LOW ALONG ONTARIO/QUEBEC BORDER BEGINNING TO DRIFT SOUTH... WRAPPING SOME DEEPER MOISTURE AROUND ITS WESTERN/SOUTHERN FLANKS AND INTO EASTERN LAKE SUPERIOR. ONTARIO RADAR COMPOSITE SHOWING A BROAD AREA OF REFLECTIVITY WRAPPING TOWARD EASTERN LAKE SUPERIOR... SOME OF THIS NOW SHOWING UP ON THE KAPX 88D DRIFTING SOUTH ACROSS THE NORTH CHANNEL TOWARD MANITOULIN ISLAND. HAVEN`T SEEN ANY PRECIP REPORTS OUT OF WAWA OR SOO ONTARIO WITH THIS...DOES APPEAR TO BE A NARROW LAKE ENHANCED BAND DRIFTING IN OFF LAKE SUPERIOR. THERE IS ALSO AN EAST-WEST ORIENTED CONVERGENCE BAND EXTENDING OUT INTO LAKE HURON FROM JUST EAST OF THE STRAITS...WHICH HAS ALSO BEEN THE FOCUS FOR SOME RADAR RETURNS OFF PRESQUE ISLE LIGHT. PRECIPITATION PROBLEMS FOR THE OVERNIGHT WILL MOST LIKELY BE CONFINED TO EASTERN UPPER. GENERAL SUBSIDENCE OVER MUCH OF NORTHERN LOWER MI SHOULD GRADUALLY PUSH INVERSION HEIGHTS DOWNWARD OVERNIGHT. SO EXPECT RAIN SHOWERS OVER NORTHWEST LOWER TO WIND DOWN AFTER MIDNIGHT. ACROSS EASTERN UPPER DEEPER MOISTURE WILL ROTATE IN FROM THE NORTH OVERNIGHT. SOME WEAK QG FORCING WITH THIS DRIVEN MOSTLY BY THERMAL ADVECTION...THOUGH SOME LOW/MID LEVEL FRONTOGENESIS/FRONTOLYSIS COUPLING HELPING OUT AS WELL. INCREASED MOISTURE...WEAK FORCING...AND SOME CONTRIBUTION OFF LAKE SUPERIOR (POSSIBLY AIDED BY INCREASING LOW LEVEL CONVERGENCE ALONG INVERTED TROUGH DRIFTING SOUTH ACROSS LAKE SUPERIOR) WILL INCREASE THE THREAT FOR SHOWERS ACROSS MUCH OF EASTERN UPPER AFTER 06Z. SOME OF THIS MAY JUST GRAZE FAR NORTHEAST LOWER DURING THE EARLY MORNING HOURS AS WELL. MEANWHILE...EXPECT AREAS EAST OF A CAD-APN LINE WILL BE PARTLY CLOUDY FOR THE MOST PART OVERNIGHT. JPB && .PREV DISCUSSION... /ISSUED 334 PM EDT FRI OCT 12 2007/ A MYRIAD OF FORECAST CONCERNS HEADING INTO TONIGHT AND SATURDAY... NAMELY LAKE EFFECT PRECIP...CLOUD COVER...AND TEMPERATURES. EARLY AFTERNOON ANALYSIS SHOWS A RATHER CONVOLUTED UPPER PATTERN...WITH A POTENT BUT RAPIDLY OCCLUDING UPPER LOW ACROSS SOUTHEASTERN ONTARIO...AND ANOTHER PIECE OF ENERGY RIDING UP THE NORTHEAST COASTLINE (WHICH MODELS PROG TO PHASE WITH EXISTING ENERGY OVER EASTERN CANADA). THIS HAS LEFT ALL OF NORTHERN MICHIGAN IN PRONOUNCED CYCLONIC FLOW ALOFT...WITH CHANNELED VORT LOBE DROPPING THROUGH THE REGION EARLY THIS AFTERNOON WORKING IN TANDEM WITH SUFFICIENT LOW LEVEL MOISTURE (RUC 900-800MB MOISTURE IN EXCESS OF 75%) AND OVER LAKE DELTA T/S ON THE ORDER OF 15C OR BETTER TO PRODUCE A SMATTERING OF LAKE EFFECT/ENHANCED RAIN SHOWERS FOR NORTHWEST FLOW AREAS. ENERGY TRANSLATING THROUGH THE REGION HAS EVEN BEEN SUFFICIENT TO ALLOW SHOWERS TO PROGRESS MUCH FARTHER INLAND THAN TYPICALLY EXPECTED...THOUGH THIS APPEARS TO BE PARTIALLY DRIVEN BY AFTERNOON LOW LEVEL INSTABILITY. FOR TONIGHT...THE BIGGEST QUESTION REMAINS COVERAGE OF LAKE EFFECT PRECIPITATION/CLOUDS AS OVERALL CYCLONIC/NORTHWESTERLY FLOW PATTERN REMAINS INTACT. WITH ONLY SOME MINOR WARM LOW LEVEL WARMING TAKING SHAPE (H85 TEMPS RISE TO AROUND 0C BY 12Z)... OVER LAKE INSTABILITY REMAINS GOOD WITH DELTA T/S BETTER THAN 13C. IN ADDITION...LOSS OF OVER-LAND MIXING WILL CERTAINLY AID IN RESTRUCTURING SOME BANDS OF PRECIP AFTER SUNSET. HOWEVER...A PEAK UPSTREAM REVEALS LOW LEVEL DRYING MAKING PROGRESS TOWARD WESTERN LAKE SUPERIOR IN RESPONSE TO INCREASING SUBSIDENCE ON THE BACKSIDE OF ONTARIO CLOSED LOW. 12Z GFS APPEARS TO HAVE A GOOD HANDLE ON THIS OCCURRENCE...WITH FORECAST TIME HEIGHTS/RAOBS INDICATING THIS DRYING (950-800MB RH DROPS TO LESS THAN 40%) SLIPPING INTO NORTHERN LOWER MICHIGAN OVERNIGHT. THUS...WHILE DO EXPECT SOME LAKE EFFECT PRECIP TO CONTINUE INTO THE EARLY OVERNIGHT HOURS...APPEARS LOW LEVEL DRYING MAY BRING AN ABRUPT END AFTER MIDNIGHT ACROSS NORTHERN LOWER COUNTIES...WHILE EASTERN UPPER HANGS ONTO RESIDUAL SHOWERS IN BETTER MOISTURE ENVIRONMENT. IN ADDITION...WILL BE ON THE LOOKOUT FOR ADDITIONAL SHOWER CHANCES ACROSS MAINLY FAR NORTHEAST COUNTIES LATE TONIGHT INTO TOMORROW AS UPPER LOW FURTHER OCCLUDES AND GETS SHUNTED SOUTH...WITH INCREASING SUPPORT FOR ASCENT AS VORT MAX DROPS ACROSS LAKE HURON. APPEARS BEST 700-500MR -DIVQ WILL RESIDE JUST EAST OF THE REGION...THOUGH CERTAINLY CANNOT RULE OUT A FEW SHOWERS... PARTICULARLY WITH A BIT OF LAKE ENHANCEMENT ON NORTHWESTERLY FLOW. AS FOR CLOUD COVER/TEMPERATURES...CELLULAR NATURE OF CU/STRATOCU THIS AFTERNOON OVER THE SOUTHEAST CWA PORTENDS LIKELY RAPID CLEARING TOWARD SUNSET...WITH DOWNSLOPE FLOW/LOSS OF SYNOPTIC SUPPORT AIDING THIS PROCESS. ELSEWHERE...APPEARS LAKE DRIVEN STRATOCU LIKELY TO HOLD FOR A WHILE OVER NORTHWEST LOWER/EASTERN UPPER BEFORE AFOREMENTIONED LOW LEVEL DRYING KICKS IN ACROSS LAKE MICHIGAN OVERNIGHT. LATE TONIGHT INTO TOMORROW...THE BIG QUESTION REMAINS JUST HOW FAR WEST LOW LEVEL MOISTURE IN ASSOCIATION WITH DEEPLY OCCLUDED LOW TO THE EAST WILL WRAP. VARIOUS MODELS HAVE THEIR OWN SOLUTIONS REGARDING WESTWARD DEGREE OF RH INTO TOMORROW AFTERNOON...BUT A SUBJECTIVE ANALYSIS FROM LATE AFTERNOON VISIBLE SATELLITE/PLACEMENT OF UPPER LOW WOULD SUGGEST LOW/MID LEVEL MOISTURE WRAPPING BACK INTO EASTERN UPPER AND FAR NORTHERN LOWER LATE TONIGHT INTO MUCH OF TOMORROW. OBVIOUSLY...TEMPERATURES HIGHLY DEPENDENT ON DEGREE OF CLOUD COVER (REFERENCE THIS MORNING WITH COOLER THAN EXPECTED READINGS UNDER CLEARING SKIES). BEST GUESS FOR TONIGHT GIVEN ALREADY COOL READINGS THIS AFTERNOON IS UPPER 20S TO MID 30S AWAY FROM THE LAKE SHORES. HEADING INTO TOMORROW...TEMP FORECAST RATHER IFFY PENDING PLACEMENT OF CLOUD COVER...BUT WILL TREND THINGS UPWARD INTO THE LOW/MID 50S ACROSS THE SOUTH WHERE MORE SUNSHINE EXPECTED IN A DEEP LAYER DRY AIRMASS (900-300MB RH ONLY AROUND 30-40%)...BUT HOLD NUMBERS DOWN ACROSS THE NORTHEAST WHERE CLOUDS EXPECTED TO LINGER THROUGH MUCH OF THE DAY. MARINE SIDE OF THINGS...APPROACH OF VORT LOBE/SURFACE LOW OVERNIGHT APPEARS IT WILL TIGHTEN THE GRADIENT SUFFICIENT TO KICK UP WINDS ON AREA WATERS...CENTERED ON ABOUT 12Z WITH ISALLOBARIC COMPONENT GREATEST. WHILE SMALL CRAFT ADVISORY CONDITIONS NOT CURRENTLY BEING MET IN MOST SPOTS...ADVISORY CONDITIONS APPEAR LIKELY LATE TONIGHT INTO MIDDAY ON FRIDAY. WILL THEREFORE EXPAND SMALL CRAFTS THROUGH 18Z BEFORE GRADIENT AGAIN WEAKENS. EARLIER COMMENT ABOUT POTENTIAL GALES ON THE HURON SIDE APPEARS JUSTIFIED...BUT THIS EVENT LOOKS TO COME JUST A TAD SHORT WITH A MAXIMUM WIND OF ONLY 30 TO 35 KNOTS AT THE TOP OF THE MIXED LAYER. STILL SOMETHING TO BE WATCHED WITH COASTAL CONVERGENCE COMING INTO PLAY OVERNIGHT...BUT WILL HOLD OFF ON GALE ISSUANCE FOR NOW. LAWRENCE REMAINDER OF THE FORECAST...(SATURDAY NIGHT THROUGH NEXT FRIDAY)... LOTS OF QUESTIONS THROUGH THIS PERIOD AS THE EXTENDED MODELS ARE HAVING TROUBLE RESOLVING THE MOVEMENT OF THE CUTOFF UPPER LOW CURRENTLY EVIDENT ON WATER VAPOR LOOP SPINNING ITS WHEELS OVER THE NORTH CENTRAL CALIFORNIA COAST. THE MOVEMENT AND AFFECTS OF THIS FEATURE ON THE WESTERN GREAT LAKES WILL BE THE MAIN FOCUS OF THIS PORTION OF THE PACKAGE. SATURDAY NIGHT...RETROGRADING UPPER LOW TO OUR NORTHEAST WILL CONTINUE TO SINK SOUTH AND EVENTUALLY EASTWARD. THE NAM IS MUCH MORE BULLISH WITH THE SOUTHWEST PUSH OF LOW LEVEL MOISTURE. MEANWHILE...THE GFS/UKMET ARE IN AGREEMENT THAT THE DEEPER MOISTURE REMAINS CONFINED TO THE NORTHEASTERN FORECAST AREA AND THIS SCENARIO SEEMS PLAUSIBLE GIVEN CURRENT SATELLITE TRENDS. MEAN 900-700 MB RH SHOWS A LARGE RANGE FROM ONLY ABOUT 20 PERCENT SOUTHWEST TO BETWEEN 80 AND 90 PERCENT NORTHEAST AT 00Z SUN. THEREFORE...PARTLY CLOUDY TO MOSTLY CLEAR SKIES EXPECTED SOUTHWEST BUT REMAINING MOSTLY CLOUDY NORTHEAST. DEEPER MOISTURE ACROSS THE NORTHEAST SLOWLY DISSIPATES/MOVES NORTHEAST OVERNIGHT AS WELL. THERE WILL LIKELY BE A LARGE RANGE OF LOW TEMPERATURES AS WINDS ARE EXPECTED TO BE 10 KNOTS OR LESS. LOW RANGING FROM THE UPPER 20S INTERIOR SOUTHWEST TO THE UPPER 30S NORTHEAST (DUE TO THE ABUNDANT CLOUD COVER). SUNDAY...PESKY UPPER LOW CONTINUES TO SWIRL TO THE EAST AWAY FROM THE AREA. MEANWHILE...ATTENTION WILL TURN TO OUR SOUTHWEST AS ANOTHER UPPER LOW (IN THE SERIES) BEGINS TO TRACK NORTHEAST TOWARD THE WESTERN GREAT LAKES. MODEL SOUNDINGS/CROSS SECTIONS INCREASE MID AND UPPER LEVEL MOISTURE SUNDAY AFTERNOON BUT NOT BEFORE A GOOD DEAL OF SUNSHINE SUNDAY MORNING. HIGHS IN THE SEASONABLE MIDDLE 50S TO AROUND 60. SUNDAY NIGHT THOUGH NEXT WEDNESDAY...EXTENDED MODELS ALL BRING A DIFFERENT SPIN TO THE MOVEMENT/TIMING OF THE SOUTHWESTERN UPPER LOW. BLOCKING NO LONGER APPEARS TO BE STRONG ENOUGH TO HOLD THIS SYSTEM AT BAY. MODELS IN ONE FORM OR ANOTHER PROGRESS THIS FEATURE TOWARD THE WESTERN GREAT LAKES AND ACTUALLY STALL IT OUT (WHILE WEAKENING IT) OVER OR JUST TO THE SOUTH OF THE AREA. TO START THE BALL ROLLING...A BAND OF FRONTOGENESIS IS SHOWN TO OVERSPREAD THE REGION SUNDAY NIGHT INTO MONDAY LEADING TO CHANCE POPS ACROSS NORTHERN LOWER. THE UPPER LOW THEN GETS CLOSE ENOUGH ON TUESDAY AND POSSIBLY STALLS OUT OVER THE REGION BY WEDNESDAY SO WILL ADD POPS INTO THESE TIME PERIODS AS WELL. HIGHS GENERALLY IN THE MIDDLE 50S TO LOWER 60S WITH LOWS IN THE UPPER 30S TO LOWER 40S. THURSDAY AND FRIDAY...AFTER COLLABORATION WITH SURROUNDING OFFICES...WILL ASSUME THAT THE UPPER LOW HAS DISSIPATED/MOVED OFF TO OUR EAST ON THURSDAY (WHICH MAY BE A STRETCH). THIS WILL LEAD TO LEAVING THURSDAY DRY FOR NOW. YET ANOTHER UPPER LOW IN WHAT SEEMS LIKE AN ENDLESS PARADE THEN MARCHES TOWARD THE AREA SO WILL BRING IN MORE CHANCE POPS FOR FRIDAY. SIMILAR TEMPERATURES WITH HIGHS IN THE MIDDLE 50S TO AROUND 60 AND LOWS BETWEEN 40 AND 45. SULLIVAN && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 334 PM EDT FRI OCT 12 2007 .DISCUSSION...A MYRIAD OF FORECAST CONCERNS HEADING INTO TONIGHT AND SATURDAY...NAMELY LAKE EFEFCT PRECIP...CLOUD COVER...AND TEMPERATURES. EARLY AFTERNOON ANALYSIS SHOWS A RATHER CONVOLUTED UPPER PATTERN...WITH A POTENT BUT RAPIDLY OCCLUDING UPPER LOW ACROSS SOUTHEASTERN ONTARIO...AND ANOTHER PIECE OF ENERGY RIDING UP THE NORTHEAST COASTLINE (WHICH MODELS PROG TO PHASE WITH EXISTING ENERGY OVER EASTERN CANADA). THIS HAS LEFT ALL OF NORTHERN MICHIGAN IN PRONOUNCED CYCLONIC FLOW ALOFT...WITH CHANNELED VORT LOBE DROPPING THROUGH THE REGION EARLY THIS AFTERNOON WORKING IN TANDEM WITH SUFFICIENT LOW LEVEL MOISTURE (RUC 900-800MB MOISTURE IN EXCESS OF 75%) AND OVERLAKE DELTA T/S ON THE ORDER OF 15C OR BETTER TO PRODUCE A SMATTERING OF LAKE EFFECT/ENHANCED RAIN SHOWERS FOR NORTHWEST FLOW AREAS. ENERGY TRANSLATING THROUGH THE REGION HAS EVEN BEEN SUFFICIENT TO ALLOW SHOWERS TO PROGRESS MUCH FARTHER INLAND THAN TYPICALLY EXPECTED...THOUGH THIS APPEARS TO BE PARTIALLY DRIVEN BY AFTERNOON LOW LEVEL INSTABILITY. FOR TONIGHT...THE BIGGEST QUESTION REMAINS COVERAGE OF LAKE EFFECT PRECIPITATION/CLOUDS AS OVERALL CYCLONIC/NORTHWESTERLY FLOW PATTERN REMAINS INTACT. WITH ONLY SOME MINOR WARM LOW LEVEL WARMING TAKING SHAPE (H85 TEMPS RISE TO AROUND 0C BY 12Z)...OVERLAKE INSTABILITY REMAINS GOOD WITH DELTA T/S BETTER THAN 13C. IN ADDITION...LOSS OF OVER-LAND MIXING WILL CERTAINLY AID IN RESTRUCTURING SOME BANDS OF PRECIP AFTER SUNSET. HOWEVER...A PEAK UPSTREAM REVEALS LOW LEVEL DRYING MAKING PROGRESS TOWARD WESTERN LAKE SUPERIOR IN RESPONSE TO INCREASING SUBSIDENCE ON THE BACKSIDE OF ONTARIO CLOSED LOW. 12Z GFS APPEARS TO HAVE A GOOD HANDLE ON THIS OCCURRENCE...WITH FORECAST TIME HEIGHTS/RAOBS INDICATING THIS DRYING (950-800MB RH DROPS TO LESS THAN 40%) SLIPPING INTO NORTHERN LOWER MICHIGAN OVERNIGHT. THUS...WHILE DO EXPECT SOME LAKE EFFECT PRECIP TO CONTINUE INTO THE EARLY OVERNIGHT HOURS...APPEARS LOW LEVEL DRYING MAY BRING AN ABRUPT END AFTER MIDNIGHT ACROSS NORTHERN LOWER COUNTIES...WHILE EASTERN UPPER HANGS ONTO RESIDUAL SHOWERS IN BETTER MOISTURE ENVIRONMENT. IN ADDITION...WILL BE ON THE LOOKOUT FOR ADDITIONAL SHOWER CHANCES ACROSS MAINLY FAR NORTHEAST COUNTIES LATE TONIGHT INTO TOMORROW AS UPPER LOW FURTHER OCCLUDES AND GETS SHUNTED SOUTH...WITH INCREASING SUPPORT FOR ASCENT AS VORT MAX DROPS ACROSS LAKE HURON. APPEARS BEST 700-500MR -DIVQ WILL RESIDE JUST EAST OF THE REGION...THOUGH CERTAINLY CANNOT RULE OUT A FEW SHOWERS... PARTICULARLY WITH A BIT OF LAKE ENHANCEMENT ON NORTHWESTERLY FLOW. AS FOR CLOUD COVER/TEMPERATURES...CELLULAR NATURE OF CU/STRATOCU THIS AFTERNOON OVER THE SOUTHEAST CWA PORTENDS LIKELY RAPID CLEARING TOWARD SUNSET...WITH DOWNSLOPE FLOW/LOSS OF SYNOPTIC SUPPORT AIDING THIS PROCESS. ELSEWHERE...APPEARS LAKE DRIVEN STRATOCU LIKELY TO HOLD FOR A WHILE OVER NORTHWEST LOWER/EASTERN UPPER BEFORE AFOREMENTIONED LOW LEVEL DRYING KICKS IN ACROSS LAKE MICHIGAN OVERNIGHT. LATE TONIGHT INTO TOMORROW...THE BIG QUESTION REMAINS JUST HOW FAR WEST LOW LEVEL MOISTURE IN ASSOCIATION WITH DEEPLY OCCLUDED LOW TO THE EAST WILL WRAP. VARIOUS MODELS HAVE THEIR OWN SOLUTIONS REGARDING WESTWARD DEGREE OF RH INTO TOMORROW AFTERNOON...BUT A SUBJECTIVE ANALYSIS FROM LATE AFTERNOON VISIBLE SATELLITE/PLACEMENT OF UPPER LOW WOULD SUGGEST LOW/MID LEVEL MOISTURE WRAPPING BACK INTO EASTERN UPPER AND FAR NORTHERN LOWER LATE TONIGHT INTO MUCH OF TOMORROW. OBVIOUSLY...TEMPERATURES HIGHLY DEPENDENT ON DEGREE OF CLOUD COVER (REFERENCE THIS MORNING WITH COOLER THAN EXPECTED READINGS UNDER CLEARING SKIES). BEST GUESS FOR TONIGHT GIVEN ALREADY COOL READINGS THIS AFTERNON IS UPPER 20S TO MID 30S AWAY FROM THE LAKESHORES. HEADING INTO TOMORROW...TEMP FORECAST RATHER IFFY PENDING PLACEMENT OF CLOUD COVER...BUT WILL TREND THINGS UPWARD INTO THE LOW/MID 50S ACROSS THE SOUTH WHERE MORE SUNSHINE EXPECTED IN A DEEP LAYER DRY AIRMASS (900-300MB RH ONLY AROUND 30-40%)...BUT HOLD NUMBERS DOWN ACROSS THE NORTHEAST WHERE CLOUDS EXPECTED TO LINGER THROUGH MUCH OF THE DAY. MARINE SIDE OF THINGS...APPROACH OF VORT LOBE/SURFACE LOW OVERNIGHT APPEARS IT WILL TIGHTEN THE GRADIENT SUFFICIENT TO KICK UP WINDS ON AREA WATERS...CENTERED ON ABOUT 12Z WITH ISALLOBARIC COMPONENT GREATEST. WHILE SMALL CRAFT ADVISORY CONDITIONS NOT CURRENTLY BEING MET IN MOST SPOTS...ADVISORY CONDITIONS APPEAR LIKELY LATE TONIGHT INTO MIDDAY ON FRIDAY. WILL THEREFORE EXPAND SMALL CRAFTS THROUGH 18Z BEFORE GRADIENT AGAIN WEAKENS. EARLIER COMMENT ABOUT POTENTIAL GALES ON THE HURON SIDE APPEARS JUSTIFIED...BUT THIS EVENT LOOKS TO COME JUST A TAD SHORT WITH A MAXIMUM WIND OF ONLY 30 TO 35 KNOTS AT THE TOP OF THE MIXED LAYER. STILL SOMETHING TO BE WATCHED WITH COASTAL CONVERGENCE COMING INTO PLAY OVERNIGHT...BUT WILL HOLD OFF ON GALE ISSUANCE FOR NOW. LAWRENCE REMAINDER OF THE FORECAST...(SATURDAY NIGHT THROUGH NEXT FRIDAY)...LOTS OF QUESTIONS THROUGH THIS PERIOD AS THE EXTENDED MODELS ARE HAVING TROUBLE RESOLVING THE MOVEMENT OF THE CUTOFF UPPER LOW CURRENTLY EVIDENT ON WATER VAPOR LOOP SPINNING ITS WHEELS OVER THE NORTH CENTRAL CALIFORNIA COAST. THE MOVEMENT AND AFFECTS OF THIS FEATURE ON THE WESTERN GREAT LAKES WILL BE THE MAIN FOCUS OF THIS PORTION OF THE PACKAGE. SATURDAY NIGHT...RETROGRADING UPPER LOW TO OUR NORTHEAST WILL CONTINUE TO SINK SOUTH AND EVENTUALLY EASTWARD. THE NAM IS MUCH MORE BULLISH WITH THE SOUTHWEST PUSH OF LOW LEVEL MOISTURE. MEANWHILE...THE GFS/UKMET ARE IN AGREEMENT THAT THE DEEPER MOISTURE REMAINS CONFINED TO THE NORTHEASTERN FORECAST AREA AND THIS SCENARIO SEEMS PLAUSIBLE GIVEN CURRENT SATELLITE TRENDS. MEAN 900-700 MB RH SHOWS A LARGE RANGE FROM ONLY ABOUT 20 PERCENT SOUTHWEST TO BETWEEN 80 AND 90 PERCENT NORTHEAST AT 00Z SUN. THEREFORE...PARTLY CLOUDY TO MOSTLY CLEAR SKIES EXPECTED SOUTHWEST BUT REMAINING MOSTLY CLOUDY NORTHEAST. DEEPER MOISTURE ACROSS THE NORTHEAST SLOWLY DISSIPATES/MOVES NORTHEAST OVERNIGHT AS WELL. THERE WILL LIKELY BE A LARGE RANGE OF LOW TEMPERATURES AS WINDS ARE EXPECTED TO BE 10 KNOTS OR LESS. LOW RANGING FROM THE UPPER 20S INTERIOR SOUTHWEST TO THE UPPER 30S NORTHEAST (DUE TO THE ABUNDANT CLOUD COVER). SUNDAY...PESKY UPPER LOW CONTINUES TO SWIRL TO THE EAST AWAY FROM THE AREA. MEANWHILE...ATTENTION WILL TURN TO OUR SOUTHWEST AS ANOTHER UPPER LOW (IN THE SERIES) BEGINS TO TRACK NORTHEAST TOWARD THE WESTERN GREAT LAKES. MODEL SOUNDINGS/CROSS SECTIONS INCREASE MID AND UPPER LEVEL MOISTURE SUNDAY AFTERNOON BUT NOT BEFORE A GOOD DEAL OF SUNSHINE SUNDAY MORNING. HIGHS IN THE SEASONABLE MIDDLE 50S TO AROUND 60. SUNDAY NIGHT THOUGH NEXT WEDNESDAY...EXTENDED MODELS ALL BRING A DIFFERENT SPIN TO THE MOVEMENT/TIMING OF THE SOUTHWESTERN UPPER LOW. BLOCKING NO LONGER APPEARS TO BE STRONG ENOUGH TO HOLD THIS SYSTEM AT BAY. MODELS IN ONE FORM OR ANOTHER PROGRESS THIS FEATURE TOWARD THE WESTERN GREAT LAKES AND ACTUALLY STALL IT OUT (WHILE WEAKENING IT) OVER OR JUST TO THE SOUTH OF THE AREA. TO START THE BALL ROLLING...A BAND OF FRONTOGENESIS IS SHOWN TO OVERSPREAD THE REGION SUNDAY NIGHT INTO MONDAY LEADING TO CHANCE POPS ACROSS NORTHERN LOWER. THE UPPER LOW THEN GETS CLOSE ENOUGH ON TUESDAY AND POSSIBLY STALLS OUT OVER THE REGION BY WEDNESDAY SO WILL ADD POPS INTO THESE TIME PERIODS AS WELL. HIGHS GENERALLY IN THE MIDDLE 50S TO LOWER 60S WITH LOWS IN THE UPPER 30S TO LOWER 40S. THURSDAY AND FRIDAY...AFTER COLLABORATION WITH SURROUNDING OFFICES...WILL ASSUME THAT THE UPPER LOW HAS DISSIPATED/MOVED OFF TO OUR EAST ON THURSDAY (WHICH MAY BE A STRETCH). THIS WILL LEAD TO LEAVING THURSDAY DRY FOR NOW. YET ANOTHER UPPER LOW IN WHAT SEEMS LIKE AN ENDLESS PARADE THEN MARCHES TOWARD THE AREA SO WILL BRING IN MORE CHANCE POPS FOR FRIDAY. SIMILAR TEMPERATURES WITH HIGHS IN THE MIDDLE 50S TO AROUND 60 AND LOWS BETWEEN 40 AND 45. SULLIVAN && .AVIATION /ISSUED 125 PM EDT FRI OCT 12 2007/ HIGH END MVFR TO LOW END VFR CONDITIONS WILL PERSIST THROUGH LATE AFTERNOON WITH INSTABILITY STRATOCU CLOUD DECK IN PLACE. OCCASIONAL LAKE EFFECT RAIN SHOWERS WILL ALSO BE NOTED AROUND KPLN/KTVC THROUGH LATE EVENING AS LOW LEVEL FLOW HOLDS NORTHWEST. EXPECT TO SEE SOME IMPROVEMENT THROUGH THE EVENING AND EARLY OVERNIGHT HOURS...INITIALLY AROUND KAPN WHERE THINGS SHOULD SCATTER BY 00Z GIVEN DIURNAL NATURE TO THE CLOUDS...AND EVENTUALLY AROUND KPLN/KTVC LATE WITH LOSS OF LOW LEVEL MOISTURE. OCCLUDED LOW PRESSURE SYSTEM DROPPING THROUGH EASTERN ONTARIO WILL THEN SPREAD ADDITIONAL MOISTURE BACK INTO NORTHERN MICHIAN TOWARD MORNING...LIKELY BRINGING AN MVFR CLOUD DECK BACK INTO ALPENA...AND PERHAPS THE OTHER TWO SITES...THOUGH CONFIDENCE ON THIS SCENARIO SUFFICIENTLY LOW TO PRECLUDE ANY MENTION OUTSIDE OF KAPN. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 125 PM EDT FRI OCT 12 2007 .AVIATION...HIGH END MVFR TO LOW END VFR CONDITIONS WILL PERSIST THROUGH LATE AFTERNOON WITH INSTABILITY STRATOCU CLOUD DECK IN PLACE. OCCASIONAL LAKE EFFECT RAIN SHOWERS WILL ALSO BE NOTED AROUND KPLN/KTVC THROUGH LATE EVENING AS LOW LEVEL FLOW HOLDS NORTHWEST. EXPECT TO SEE SOME IMPROVEMENT THROUGH THE EVENING AND EARLY OVERNIGHT HOURS...INITIALLY AROUND KAPN WHERE THINGS MAY SCATTER BY 00Z GIVEN DIURNAL NATURE TO THE CLOUDS...AND EVENTUALLY AROUND KPLN/KTVC LATE WITH LOSS OF LOW LEVEL MOISTURE. OCCLUDED LOW PRESSURE SYSTEM DROPPING THROUGH EASTERN ONTARIO WILL THEN SPREAD ADDITIONAL MOISTURE BACK INTO NORTHERN MICHIAN TOWARD MORNING...LIKELY BRINGING AN MVFR CLOUD DECK BACK INTO ALPENA...AND PERHAPS THE OTHER TWO SITES...THOUGH CONFIDENCE ON THIS SCENARIO SUFFICIENTLY LOW TO PRECLUDE ANY MENTION OUTSIDE OF KAPN. LAWRENCE && .PREV DISCUSSION... /ISSUED 1111 AM EDT FRI OCT 12 2007/ UPDATE...RIGHT ABOUT ON SCHEDULE (AVERAGE FIRST DATE IS THE 13TH)...THE FIRST SNOWFLAKES OF THE SEASON HAVE BEEN REPORTED ACROSS THE HIGHER TERRAIN THIS MORNING...AND NO SURPRISE GIVEN 12Z APX RAOB SHOWING JUST ABOUT THE ENTIRE COLUMN BELOW 0C (THOUGH CLOUD TOP TEMPS AROUND -10C JUST ABOUT THE MINIMUM TO PRODUCE SUFFICIENT ICE). OVERALL PATTERN REMAINS RATHER UNCHANGED FROM YESTERDAY... WITH DEEPLY CLOSED UPPER LOW SLOWLY OVER EASTERN ONTARIO...AND OVERALL PRONOUNCED CYCLONIC FLOW INTACT ACROSS NORTHERN MICHIGAN...BECOMING BETTER DEFINED WITH TIME AS UPPER SYSTEM SLOWLY PIVOTS SOUTHWARD. NOTABLE CHANNELED VORT ROTATING AROUND THE MAIN GYRE IN CONCERT WITH COLD LOW LEVEL AIRMASS (H85 TEMPS AROUND -3C TO -5C) AND GRADUALLY VEERING FLOW FROM THE NORTH TO NORTHWEST HAS PROVIDED LAKE EFFECT RAIN SHOWERS (WITH A LITTLE SNOW MIXED IN PER ABOVE INFO) FOR THE FAVORED AREAS ACROSS NORTHWEST LOWER...WHILE LOCATIONS FARTHER EAST HAVE ACTUALLY BEEN SEEING SOME SUN THIS MORNING GIVEN DOWNSLOPING FLOW REGIME. THE PRIMARY FORECAST CONCERN FOR THE REST OF TODAY IS THAT OF LAKE EFFECT CHANCES AS WELL AS AFTERNOON HIGHS. OVERALL PATTERN APPEARS IT WILL CHANGE LITTLE THROUGH THE DAY...WITH ONLY A GRADUAL CHANGE IN THE FLOW REGIME TOWARD PURE NORTHWEST BY MID AFTERNOON. WHILE 12Z APX RAOB WOULD HAVE YOU BELIEVE OVERALL LOW LEVEL MOISTURE NOT ALL THAT IMPRESSIVE (900-700MB RH OF LESS THAN 50%)...APPEARS EARLY MORNING SOUNDING SAMPLED INITIALLY DRIER AIRMASS OWING TO OVERNIGHT DOWNSLOPE/CLEARING SKIES. MOISTURE OBVIOUSLY SUFFICIENT FOR LAKE EFFECT PRODUCTION PER CURRENT RADAR PICS...WITH LATEST LATEST RUC INDICATIVE OF REALITY WITH 900-700MB RH IN EXCESS OF 80%. OVERALL GOING POPS FOR NORTHWEST FLOW AREAS THIS AFTERNOON LOOK TO BE ON TARGET...AND PREFER TO KEEP SCATTERED WORDING AS EXPECT AFTERNOON DISRUPTION TO OCCUR WITH INCREASING OVER-LAND MIXING (AND PERHAPS SOME DECREASE IN MOISTURE BY MID AFTERNOON). AS FAR AS TEMPERATURES ARE CONCERNED...DECIDED TO RAISE NUMBERS ACROSS THE SOUTHEAST CWA WHERE DOWNSLOPE FLOW WILL CONTINUE INTO THE AFTERNOON AND READINGS OFF TO A QUICK START. THAT SAID...STILL EXPECT TO SEE STRATOCU FILL IN FOR ALL AREAS TODAY GIVEN SUFFICIENT MOISTURE AND THERMAL TROUGHING FIRMLY IN PLACE. HIGHS UPPER 40S HIGHER TERRAIN TO LOWER 50S ELSEWHERE LOOK GOOD...EXCEPT FOR LIKELY SOME MID 50S SOUTHEAST WHERE SUN WILL LINGER A BIT LONGER THROUGH ABOUT NOON. LAWRENCE && PREV DISCUSSION...ISSUED AT 412 AM EDT FRI LATEST SURFACE/RUC ANALYSIS AND IR/WV/RADAR IMAGERY SHOW DUAL UPPER LEVEL LOWS...ONE OVER THE CHESAPEAKE BAY AND ANOTHER OVER THE ONTARIO/QUEBEC BORDER. WEAK BACKDOOR SURFACE TROUGH PROGRESSING ACROSS THE CWA WITH SOME CLEARING BEHIND THE TROUGH OVER EASTERN UPPER EAST OF I-75 AND TIP OF THE MITT AS WINDS SHIFT TO THE NORTHEAST (DOWNSLOPING)...WHILE LAKE EFFECT RAIN SHOWERS CONTINUE DOWN GRAND TRAVERSE BAY AND ALONG THE LAKE HURON COASTLINE. 850MB TEMPS APPEAR TO HAVE STABILIZED AROUND THE -3C ISOTHERM...WHILE COLD ADVECTION IS OCCURRING IN THE MID-LEVELS (INCREASING INVERSION HEIGHTS) AS THE UPPER LOW TO THE NORTH DRIFTS SLOWLY SOUTH. MAIN FORECAST CONCERNS OVER THE NEXT 24 HOURS REVOLVE AROUND PRECIP CHANCES WITH LINGERING UPPER LOW TO THE NE OF THE AREA. TODAY...UPPER LOW WILL REMAIN NEARLY STATIONARY (MAYBE A SLIGHT DRIFT TO THE SW) ALONG THE ONTARIO/QUEBEC BORDER. INVERTED NNW-SSE SURFACE TROUGH OVER WESTERN QUEBEC IS EXPECTED TO BACK OVER THE COURSE OF THE DAY...ALLOWING LOW LEVEL WINDS TO SHIFT TO MORE OF A NW DIRECTION ACROSS THE CWA. ALTHOUGH INVERSION HEIGHTS WILL SLIGHTLY INCREASE WITH ONGOING LOW/MID-LEVEL COLD ADVECTION...BACKING WIND PROFILES AND ONLY MODERATE MOISTURE (900-700MB RH 45-60 PCT) MEANS ANY LAKE EFFECT SHOWERS WILL REMAIN SCATTERED IN NATURE. REGARDLESS...A FAIR AMOUNT OF STRATO-CU WILL DEVELOP THIS AFTERNOON WITH DEEP LAYER CYCLONIC FLOW AND THERMAL TROUGHING...SO A DAY SIMILAR TO YESTERDAY LOOKS REASONABLE. HIGHS IN THE MID 40S TO LOW 50S LOOKS GOOD. TONIGHT...VORT LOBE CURRENTLY ON THE NORTHERN PERIPHERY OF THE UPPER LOW WILL ROTATE AROUND ITS WESTERN FLANK AND CLIP THE NE CWA. DEEPER MOISTURE (900-700MB RH INCREASES GREATER THAN 70 PCT) WILL SPREAD ACROSS EASTERN UPPER AND TIP OF THE MITT WHILE 850MB TEMPS REMAIN IN THE MINUS 3-4 RANGE. SHOULD THEREFORE SEE AN UPTICK IN SHOWER ACTIVITY ACROSS EASTERN UPPER DURING THE EVENING WHICH SHOULD REMAIN STEADY OVERNIGHT. SHOWERS ACROSS NORTHERN LOWER SHOULD REMAIN MORE SPOTTY IN NATURE WITHIN WNW FLOW REGIMES AS THE DEEPER MOISTURE JUST DOES NOT MAKE IT SOUTH OF M68. WINDS INCREASE AS THE PRESSURE GRADIENT TIGHTENS IN RESPONSE TO THE VORT LOBE. 850MB WINDS INCREASE TO 35 KTS OVERNIGHT AND WITH COASTAL CONVERGENCE...GALE WARNINGS MAY BE NEEDED FOR NE LOWER. WILL LET DAY CREW CONTINUE TO ASSESS THE NEW DATA...AS ITS RIGHT ON THE EDGE. SATURDAY INTO SATURDAY NIGHT...UPPER LOW GRADUALLY PULLS AWAY TO THE EAST WHILE INCREASINGLY ANTICYCLONIC FLOW AND DRIER AIR MOVES IN. DEEPEST MOISTURE WILL RESIDE OVER EASTERN UPPER ON SATURDAY...AND THEREFORE WILL SEE THE BEST CHANCE OF SHOWERS AS LOW LEVEL WINDS REMAIN STEADY IN THE NW DIRECTION. 850MB TEMPS MODERATE SOMEWHAT TO NEAR 0C...BUT WITH DELTA T/S REMAINING IN THE MID TEENS...STILL PLENTY COLD FOR LAKE EFFECT SHOWER ACTIVITY WITHIN THE NW FAVORED FLOW. BELIEVE LINGERING SHOWERS ACROSS NW LOWER WILL DISSIPATE DURING THE AFTERNOON AS DRIER AIR AND DIURNAL DISRUPTION TAKES ITS TOLL. HOWEVER...IT WILL TAKE UNTIL OVERNIGHT FOR THE DRIER AIR TO MOVE INTO EASTERN UPPER. MPC SUNDAY THROUGH TUESDAY...BLOCKED MID LEVEL TROUGH PATTERN (FEATURING CONTRA-ROTATING UPPER LOWS) THAT HAS DOMINATED THE GREAT LAKES REGION OVER THE LAST FEW DAYS STILL PROJECTED TO PULL OUT INTO THE ATLANTIC BY THE END OF THE WEEKEND...REPLACED BY MID LEVEL RIDGING AND A MODEST WARM-UP FOR SUNDAY. THIS HAS BEEN A PERSISTENT IDEA WITH THE MODEL GUIDANCE OVER THE LAST FEW DAYS LEADING TO FAIRLY HIGH CONFIDENCE IN A DRY FORECAST FEATURING PARTLY-MOSTLY SUNNY SKIES TO WRAP UP THE WEEKEND. SO...VERY LITTLE CHANGES ANTICIPATED TO THE GOING SUNDAY FORECAST. BIGGER FORECAST TROUBLES MATERIALIZE FOR EARLY NEXT WEEK HOWEVER. SPECIFICALLY...THE DEGREE OF PHASING THAT MAY OCCUR OVER THE UPPER MIDWEST/WESTERN GREAT LAKES BETWEEN A SRN STREAM UPPER LOW MIGRATING OUT OF THE PLAINS AND NRN STREAM SHORT WAVE COMING OUT OF CENTRAL CANADA. PREVIOUS GFS SOLUTIONS WERE THE MOST BULLISH WITH THIS IDEA AND LARGELY IGNORED IN FAVOR OF A WEAKER ECMWF. HOWEVER...12/00Z ECMWF DATA GOING THE WAY OF THE GFS WITH STRONGER PHASING INDICATED AND SUGGESTS BAND OF FRONTOGENETICALLY INDUCED PRECIP DEVELOPING AND SPREADING INTO THE STATE MONDAY OR MONDAY NIGHT (AGAIN SIMILAR TO THE GFS). OBVIOUSLY FORECAST CONFIDENCE IS NOT GREAT. BUT IN LIGHT OF THE LATEST ECMWF DO FEEL COMPELLED TO ADD POPS TO AT LEAST THE MONDAY AND MONDAY NIGHT PORTION OF THE FORECAST FOR NOW. IF THIS SCENARIO HOLDS PRECIP CHANCES WILL NEED TO BE FURTHER EXTENDED THROUGH TUESDAY. BUT AT THIS POINT DO NOT WANT TO COMPLETELY PLOW OVER THE GOING FORECAST...AND WILL KEEP TUESDAY DRY. ADAM && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED AVIATION NATIONAL WEATHER SERVICE MARQUETTE MI 120 PM EDT FRI OCT 12 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP UPR TROF OVER ERN CANADA WITH PAIR OF CLOSED LO CENTERS JUST S OF JAMES BAY MOVING SSW AND THE OTHER OVER THE MID ATLANTIC STATES MOVG E TENDING TO SPIN ARND EACH OTHER WITHIN THE AREA OF LOWER HGTS. THERE IS A SHARP GRADIENT OF H85-7 MSTR ON THE WRN FLANK OF THIS TROF AND TO THE E OF RDG AXIS EXTENDING FM WRN HUDSON BAY INTO THE UPR MS RIVER VALLEY. ALTHOUGH THE UPR LO NEAR JAMES BAY APPEARS TO BE MOVING JUST A BIT W OF DUE S...WV IMAGERY INDICATES DEEPER MSTR ON ITS NW FLANK IS TENDING TO PUSH MORE TO THE W ACRS NCNTRL ONTARIO. EVEN THOUGH THE DEEPER MSTR IS CURRENTLY TO THE E...QUITE A BIT OF SC NOTED IN THE LLVL NLY FLOW BTWN SFC RDG AXIS OVER WRN LK SUP AND LO PRES TO THE E. 00Z TAMDAR SDNG SHOWS QUITE A BIT OF LLVL MSTR TRAPPED BLO SHARP INVRN ARND H85...MARKING THE SUBSIDENCE INVRN ABV LLVL THERMAL TROFFING. SCT LK EFFECT SHRA ARE MOST PERSISTENT OVER THE NCNTRL ZNS WHERE LLVL NLY FLOW IS UPSLOPING. EVEN THOUGH THE LOWEST TEMP AT THE INVRN BASE IS ONLY -6C...NOT TYPICALLY LO ENUF TO SUPPORT ICE NUCLEATION...SOME SN HAS MIXED IN WITH THE RA SINCE LAST EVNG OVER THE HIER TERRAIN. MORE BRKS IN THE CLD NOTED OVER THE SCNTRL WHERE LLVL FLOW IS DOWNSLOPING AND OVER THE W...CLOSER TO THE RDG AXIS AND DRIER LLVL AIR SHOWN ON THE 00Z YPL/INL RAOBS. ANOTHER SHRTWV OVER SCNTRL CAN IS LIFTING NEWD OVER RDG AXIS JUST TO THE W OF THE CWA AND BRINGING A BAND OF CLD/SHRA AS FAR E AS WRN MN. MAIN FCST CONCERNS THIS PACKAGE ARE CLD TRENDS/SHRA CHCS IN NNW FLOW THAT IS FCST TO PERSIST BTWN RDG TO THE W AND AREA OF LOWER HGTS TO THE E. ONE CHALLENGE WL BE DETERMINING WHETHER ANY DEEPER MSTR TO THE E ASSOCIATED WITH UPR LO JUST S OF JAMES BAY CAN ROTATE FAR ENUF TO THE W TO BRING ANY ENHANCEMENT TO THE LK EFFECT SHRA OVER LK SUP. BOTH THE GFS/NAM HAVE TRENDED STEADILY WWD WITH TRACK/POSITION OF UPR LO S OF JAMES BAY MOVING TO THE SSW. THE 00Z NAM SHOWS THE HIER H7 RH BACKING INTO THE E HALF OF LK SUP BY 00Z THIS EVNG BUT REMAINING JUST TO THE NE OF THE LAND CWA THRU THAT TIME. AT THE SAME TIME...MODEL SHOWS THE LLVL FLOW BACKING MORE NW THRU THE DAY AS A SFC HI CENTER BLDS INTO WI. THIS CHANGE IN FLOW SHOULD ALLOW MORE CLRG OVER THE NCNTRL ZNS AS FLOW OFF LK SUP BECOMES LESS FVRBL BUT MORE CLD OVER THE E. HOWEVER...ANY PCPN SHOULD TEND TO DIMINISH WITH DIURNAL HTG TENDING TO DISRUPT ANY LK EFFECT PCPN AND LOWERING LLVL RH WITH INFUSION OF DRIER AIR FM THE NW/INSOLATION. MIXING TO H85 OR SO ON NAM FCST SDNGS YIELDS HI TEMPS ARND 45 OVER THE HIER TERRAIN OF THE NW TO THE LO 50S OVER THE SCNTRL ARND MNM. TNGT...NAM IS MORE AGGRESSIVE AT BACKING MORE SUBSTANTIAL MSTR SWWD THAN THE GFS. CONSIDERING RECENT MODEL TRENDS IN HI AMPLITUDE BLOCKING PATTERN AS WELL AS WV IMAGERY SHOWING DEEPER MSTR BACKING FARTHER W...WL TEND TOWARD THE NAM FCST SCENARIO. NAM EVEN GENERATES SOME LGT PCPN OVER THE ERN ZNS WHERE LLVL CYC NW FLOW WL HAVE A LONGER FETCH ACRS THE ERN LK IN PRESENCE OF H85 THERMAL TROFFING. ADDED CHC POPS FOR THESE LK EFFECT SHRA OVER AREAS NR LK SUP E OF MUNISING AFT MIDNGT WHEN DEEPER MSTR ARRIVES. TENDED TOWARD THE HIER ETA MOS FOR THE ERN ZNS BUT TOWARD THE LOWER GFS MOS FOR THE INTERIOR W...WHERE SKIES ARE LIKELY TO REMAIN MOCLR IN PRESENCE OF PWAT BTWN 0.25 AND 0.50 INCH. TENDED TOWARD THE SLOWER NAM AGAIN ON SAT WITH MORE MSTR/CLDS/CHC POPS LINGERING OVER THE ERN ZNS WITH PERSISTENT CYC NW LLVL FLOW UNDER DEEPER MSTR. THERE WL BE MORE SUNSHINE OVER THE W...AND MIXING TO H85 ON NAM FCST SDNGS SUPPORTS HI TEMPS IN THE MID-UPR 50S RANGE OVER THE W AND SCNTRL. NAM FINALLY SHOWS CLOSED LO PULLING FAR ENUF TO THE E ON SAT NGT THAT MID LVL MSTR BEGINS TO DEPART THE ERN ZNS. LOOKS LIKE A CHILLY NGT SETTING UP OVER THE INTERIOR W WITH LGT WINDS UNDER SFC RDG AXIS. WL GO NEAR THE LO END OF MOS GUIDANCE IN THESE AREAS BUT NOT TOO CHILLY AS NAM SHOWS PWAT NO LOWER THAN ABOUT 0.45 INCH. PER NCEP GUIDANCE...HAVE TRENDED TOWARD A 00Z CNDN/12Z ECMWF SCENARIO FOR SUN INTO MON. THESE MODELS SHOW A NRN BRANCH SHRTWV MOVING INTO THE UPR GRT LKS ON SUN AND SUPPRESSING POTENT SHRTWV IN THE SRN BRANCH FOR THE MOST PART TO THE S. THIS SCENARIO WOULD ALSO BE MORE CONSISTENT WITH THE MORE BLOCKY UPR PATTERN THAT HAS DVLPD OVER ERN CANADA. TO MESH BETTER WITH SURROUNDING OFFICES...BUMPED POPS UP TO 20 ALG THE WI BORDER AND EVEN TO 30 IN SRN MNM COUNTY ON SUN NGT WHEN CNDN MODEL SHOWS SHRTWV INTERACTING WITH SOMEWHAT HIER MSTR OVER WI. MAINTAINED DRY FCST FARTHER N WHERE DRY AIR WL BE MORE RESILIENT. TENDED TO DCRS CLD COVER ON MON WITH HI PRES UNDER UPR RDGING IN SCNTRL CAN BLDG INTO THE UPR LKS PER CNDN MODEL AND MOST RECENT NCEP MANUAL GUIDANCE. COORDINATED WITH APX/GRB/DLH. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... CIGS WILL CONTINUE MVFR/VFR AT KCMX AND KSAW WHILE LONGER INTO THIS EVENING WITH LAKE EFFECT CLOUDS CONTINUING TO AFFECT THE SITE THROUGH THEN UNTIL THE WIND TURNS WEST AND STARTS BRINGING A BIT OF DRIER AIR IN. WITH DIURNAL HEATING AGAIN SAT MORNING...VFR/MVFR DECK WILL REFORM AGAIN WITH SOME LAKE CONTRIBUTION TO HELP FORM THE CLOUDS. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT THE PRES GRADIENT TO TIGHTEN TODAY INTO SATURDAY OVER ERN LAKE SUPERIOR AS A MID LEVEL AND SURFACE LOW DROP SOUTH THROUGH ERN ONTARIO AND THE SFC RDG FROM HUDSON BAY TO THE UPPER MISSISSIPPI VALLEY REMAINS IN PLACE. SO...NW WINDS WILL BACK NW AND INCREASE TO 15 TO 25 KT TODAY AND TO 30 KT LATE TONIGHT AND SATURDAY OVER THE EAST HALF PUSHING WAVE HEIGHTS INTO THE 5 TO 8 FT RANGE. WINDS WILL DIMINISH SAT NIGHT INTO SUN AS HIGH PRES BUILDS INTO THE REGION. E TO NE WINDS WILL DEVELOP FROM MON INTO TUE AS LOW PRES OVER THE CENTRAL PLAINS GRADUALLY SLIDES TO THE ENE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KC AVIATION...MICHELS MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1111 AM EDT FRI OCT 12 2007 .UPDATE...RIGHT ABOUT ON SCHEDULE (AVERAGE FIRST DATE IS THE 13TH)...THE FIRST SNOWFLAKES OF THE SEASON HAVE BEEN REPORTED ACROSS THE HIGHER TERRAIN THIS MORNING...AND NO SURPRISE GIVEN 12Z APX RAOB SHOWING JUST ABOUT THE ENTIRE COLUMN BELOW 0C (THOUGH CLOUD TOP TEMPS AROUND -10C JUST ABOUT THE MINIMUM TO PRODUCE SUFFICIENT ICE). OVERALL PATTERN REMAINS RATHER UNCHANGED FROM YESTERDAY... WITH DEEPLY CLOSED UPPER LOW SLOWLY OVER EASTERN ONTARIO...AND OVERALL PRONOUNCED CYCLONIC FLOW INTACT ACROSS NORTHERN MICHIGAN...BECOMING BETTER DEFINED WITH TIME AS UPPER SYSTEM SLOWLY PIVOTS SOUTHWARD. NOTABLE CHANNELED VORT ROTATING AROUND THE MAIN GYRE IN CONCERT WITH COLD LOW LEVEL AIRMASS (H85 TEMPS AROUND -3C TO -5C) AND GRADUALLY VEERING FLOW FROM THE NORTH TO NORTHWEST HAS PROVIDED LAKE EFFECT RAIN SHOWERS (WITH A LITTLE SNOW MIXED IN PER ABOVE INFO) FOR THE FAVORED AREAS ACROSS NORTHWEST LOWER...WHILE LOCATIONS FARTHER EAST HAVE ACTUALLY BEEN SEEING SOME SUN THIS MORNING GIVEN DOWNSLOPING FLOW REGIME. THE PRIMARY FORECAST CONCERN FOR THE REST OF TODAY IS THAT OF LAKE EFFECT CHANCES AS WELL AS AFTERNOON HIGHS. OVERALL PATTERN APPEARS IT WILL CHANGE LITTLE THROUGH THE DAY...WITH ONLY A GRADUAL CHANGE IN THE FLOW REGIME TOWARD PURE NORTHWEST BY MID AFTERNOON. WHILE 12Z APX RAOB WOULD HAVE YOU BELIEVE OVERALL LOW LEVEL MOISTURE NOT ALL THAT IMPRESSIVE (900-700MB RH OF LESS THAN 50%)...APPEARS EARLY MORNING SOUNDING SAMPLED INITIALLY DRIER AIRMASS OWING TO OVERNIGHT DOWNSLOPE/CLEARING SKIES. MOISTURE OBVIOUSLY SUFFICIENT FOR LAKE EFFECT PRODUCTION PER CURRENT RADAR PICS...WITH LATEST LATEST RUC INDICATIVE OF REALITY WITH 900-700MB RH IN EXCESS OF 80%. OVERALL GOING POPS FOR NORTHWEST FLOW AREAS THIS AFTERNOON LOOK TO BE ON TARGET...AND PREFER TO KEEP SCATTERED WORDING AS EXPECT AFTERNOON DISRUPTION TO OCCUR WITH INCREASING OVER-LAND MIXING (AND PERHAPS SOME DECREASE IN MOISTURE BY MID AFTERNOON). AS FAR AS TEMPERATURES ARE CONCERNED...DECIDED TO RAISE NUMBERS ACROSS THE SOUTHEAST CWA WHERE DOWNSLOPE FLOW WILL CONTINUE INTO THE AFTERNOON AND READINGS OFF TO A QUICK START. THAT SAID...STILL EXPECT TO SEE STRATOCU FILL IN FOR ALL AREAS TODAY GIVEN SUFFICIENT MOISTURE AND THERMAL TROUGHING FIRMLY IN PLACE. HIGHS UPPER 40S HIGHER TERRAIN TO LOWER 50S ELSEWHERE LOOK GOOD...EXCEPT FOR LIKELY SOME MID 50S SOUTHEAST WHERE SUN WILL LINGER A BIT LONGER THROUGH ABOUT NOON. LAWRENCE && .PREV DISCUSSION... /ISSUED 712 AM EDT FRI OCT 12 2007/ AVIATION...SCATTERED LAKE EFFECT SHOWERS WILL BE THE RULE THROUGH THE DAY...MOSTLY IMPACTING TVC AND APN. WINDS SHIFT TO A WNW DIRECTION TONIGHT WHEN PELLSTON LOOKS TO GET IN ON THE SHOWER ACTIVITY AS WELL. EXPECT MAINLY VFR CONDITIONS OUTSIDE OF RAIN SHOWERS WHERE OCCASIONAL MVFR CEILINGS ANTICIPATED. MPC && PREV DISCUSSION...ISSUED AT 412 AM EDT FRI LATEST SURFACE/RUC ANALYSIS AND IR/WV/RADAR IMAGERY SHOW DUAL UPPER LEVEL LOWS...ONE OVER THE CHESAPEAKE BAY AND ANOTHER OVER THE ONTARIO/QUEBEC BORDER. WEAK BACKDOOR SURFACE TROUGH PROGRESSING ACROSS THE CWA WITH SOME CLEARING BEHIND THE TROUGH OVER EASTERN UPPER EAST OF I-75 AND TIP OF THE MITT AS WINDS SHIFT TO THE NORTHEAST (DOWNSLOPING)...WHILE LAKE EFFECT RAIN SHOWERS CONTINUE DOWN GRAND TRAVERSE BAY AND ALONG THE LAKE HURON COASTLINE. 850MB TEMPS APPEAR TO HAVE STABILIZED AROUND THE -3C ISOTHERM...WHILE COLD ADVECTION IS OCCURRING IN THE MID-LEVELS (INCREASING INVERSION HEIGHTS) AS THE UPPER LOW TO THE NORTH DRIFTS SLOWLY SOUTH. MAIN FORECAST CONCERNS OVER THE NEXT 24 HOURS REVOLVE AROUND PRECIP CHANCES WITH LINGERING UPPER LOW TO THE NE OF THE AREA. TODAY...UPPER LOW WILL REMAIN NEARLY STATIONARY (MAYBE A SLIGHT DRIFT TO THE SW) ALONG THE ONTARIO/QUEBEC BORDER. INVERTED NNW-SSE SURFACE TROUGH OVER WESTERN QUEBEC IS EXPECTED TO BACK OVER THE COURSE OF THE DAY...ALLOWING LOW LEVEL WINDS TO SHIFT TO MORE OF A NW DIRECTION ACROSS THE CWA. ALTHOUGH INVERSION HEIGHTS WILL SLIGHTLY INCREASE WITH ONGOING LOW/MID-LEVEL COLD ADVECTION...BACKING WIND PROFILES AND ONLY MODERATE MOISTURE (900-700MB RH 45-60 PCT) MEANS ANY LAKE EFFECT SHOWERS WILL REMAIN SCATTERED IN NATURE. REGARDLESS...A FAIR AMOUNT OF STRATO-CU WILL DEVELOP THIS AFTERNOON WITH DEEP LAYER CYCLONIC FLOW AND THERMAL TROUGHING...SO A DAY SIMILAR TO YESTERDAY LOOKS REASONABLE. HIGHS IN THE MID 40S TO LOW 50S LOOKS GOOD. TONIGHT...VORT LOBE CURRENTLY ON THE NORTHERN PERIPHERY OF THE UPPER LOW WILL ROTATE AROUND ITS WESTERN FLANK AND CLIP THE NE CWA. DEEPER MOISTURE (900-700MB RH INCREASES GREATER THAN 70 PCT) WILL SPREAD ACROSS EASTERN UPPER AND TIP OF THE MITT WHILE 850MB TEMPS REMAIN IN THE MINUS 3-4 RANGE. SHOULD THEREFORE SEE AN UPTICK IN SHOWER ACTIVITY ACROSS EASTERN UPPER DURING THE EVENING WHICH SHOULD REMAIN STEADY OVERNIGHT. SHOWERS ACROSS NORTHERN LOWER SHOULD REMAIN MORE SPOTTY IN NATURE WITHIN WNW FLOW REGIMES AS THE DEEPER MOISTURE JUST DOES NOT MAKE IT SOUTH OF M68. WINDS INCREASE AS THE PRESSURE GRADIENT TIGHTENS IN RESPONSE TO THE VORT LOBE. 850MB WINDS INCREASE TO 35 KTS OVERNIGHT AND WITH COASTAL CONVERGENCE...GALE WARNINGS MAY BE NEEDED FOR NE LOWER. WILL LET DAY CREW CONTINUE TO ASSESS THE NEW DATA...AS ITS RIGHT ON THE EDGE. SATURDAY INTO SATURDAY NIGHT...UPPER LOW GRADUALLY PULLS AWAY TO THE EAST WHILE INCREASINGLY ANTICYCLONIC FLOW AND DRIER AIR MOVES IN. DEEPEST MOISTURE WILL RESIDE OVER EASTERN UPPER ON SATURDAY...AND THEREFORE WILL SEE THE BEST CHANCE OF SHOWERS AS LOW LEVEL WINDS REMAIN STEADY IN THE NW DIRECTION. 850MB TEMPS MODERATE SOMEWHAT TO NEAR 0C...BUT WITH DELTA T/S REMAINING IN THE MID TEENS...STILL PLENTY COLD FOR LAKE EFFECT SHOWER ACTIVITY WITHIN THE NW FAVORED FLOW. BELIEVE LINGERING SHOWERS ACROSS NW LOWER WILL DISSIPATE DURING THE AFTERNOON AS DRIER AIR AND DIURNAL DISRUPTION TAKES ITS TOLL. HOWEVER...IT WILL TAKE UNTIL OVERNIGHT FOR THE DRIER AIR TO MOVE INTO EASTERN UPPER. MPC SUNDAY THROUGH TUESDAY...BLOCKED MID LEVEL TROUGH PATTERN (FEATURING CONTRA-ROTATING UPPER LOWS) THAT HAS DOMINATED THE GREAT LAKES REGION OVER THE LAST FEW DAYS STILL PROJECTED TO PULL OUT INTO THE ATLANTIC BY THE END OF THE WEEKEND...REPLACED BY MID LEVEL RIDGING AND A MODEST WARM-UP FOR SUNDAY. THIS HAS BEEN A PERSISTENT IDEA WITH THE MODEL GUIDANCE OVER THE LAST FEW DAYS LEADING TO FAIRLY HIGH CONFIDENCE IN A DRY FORECAST FEATURING PARTLY-MOSTLY SUNNY SKIES TO WRAP UP THE WEEKEND. SO...VERY LITTLE CHANGES ANTICIPATED TO THE GOING SUNDAY FORECAST. BIGGER FORECAST TROUBLES MATERIALIZE FOR EARLY NEXT WEEK HOWEVER. SPECIFICALLY...THE DEGREE OF PHASING THAT MAY OCCUR OVER THE UPPER MIDWEST/WESTERN GREAT LAKES BETWEEN A SRN STREAM UPPER LOW MIGRATING OUT OF THE PLAINS AND NRN STREAM SHORT WAVE COMING OUT OF CENTRAL CANADA. PREVIOUS GFS SOLUTIONS WERE THE MOST BULLISH WITH THIS IDEA AND LARGELY IGNORED IN FAVOR OF A WEAKER ECMWF. HOWEVER...12/00Z ECMWF DATA GOING THE WAY OF THE GFS WITH STRONGER PHASING INDICATED AND SUGGESTS BAND OF FRONTOGENETICALLY INDUCED PRECIP DEVELOPING AND SPREADING INTO THE STATE MONDAY OR MONDAY NIGHT (AGAIN SIMILAR TO THE GFS). OBVIOUSLY FORECAST CONFIDENCE IS NOT GREAT. BUT IN LIGHT OF THE LATEST ECMWF DO FEEL COMPELLED TO ADD POPS TO AT LEAST THE MONDAY AND MONDAY NIGHT PORTION OF THE FORECAST FOR NOW. IF THIS SCENARIO HOLDS PRECIP CHANCES WILL NEED TO BE FURTHER EXTENDED THROUGH TUESDAY. BUT AT THIS POINT DO NOT WANT TO COMPLETELY PLOW OVER THE GOING FORECAST...AND WILL KEEP TUESDAY DRY. ADAM && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 712 AM EDT FRI OCT 12 2007 .AVIATION...SCATTERED LAKE EFFECT SHOWERS WILL BE THE RULE THROUGH THE DAY...MOSTLY IMPACTING TVC AND APN. WINDS SHIFT TO A WNW DIRECTION TONIGHT WHEN PELLSTON LOOKS TO GET IN ON THE SHOWER ACTIVITY AS WELL. EXPECT MAINLY VFR CONDITIONS OUTSIDE OF RAIN SHOWERS WHERE OCCASIONAL MVFR CEILINGS ANTICIPATED. MPC && .DISCUSSION...ISSUED AT 412 AM EDT FRI LATEST SURFACE/RUC ANALYSIS AND IR/WV/RADAR IMAGERY SHOW DUAL UPPER LEVEL LOWS...ONE OVER THE CHESAPEAKE BAY AND ANOTHER OVER THE ONTARIO/QUEBEC BORDER. WEAK BACKDOOR SURFACE TROUGH PROGRESSING ACROSS THE CWA WITH SOME CLEARING BEHIND THE TROUGH OVER EASTERN UPPER EAST OF I-75 AND TIP OF THE MITT AS WINDS SHIFT TO THE NORTHEAST (DOWNSLOPING)...WHILE LAKE EFFECT RAIN SHOWERS CONTINUE DOWN GRAND TRAVERSE BAY AND ALONG THE LAKE HURON COASTLINE. 850MB TEMPS APPEAR TO HAVE STABILIZED AROUND THE -3C ISOTHERM...WHILE COLD ADVECTION IS OCCURRING IN THE MID-LEVELS (INCREASING INVERSION HEIGHTS) AS THE UPPER LOW TO THE NORTH DRIFTS SLOWLY SOUTH. MAIN FORECAST CONCERNS OVER THE NEXT 24 HOURS REVOLVE AROUND PRECIP CHANCES WITH LINGERING UPPER LOW TO THE NE OF THE AREA. TODAY...UPPER LOW WILL REMAIN NEARLY STATIONARY (MAYBE A SLIGHT DRIFT TO THE SW) ALONG THE ONTARIO/QUEBEC BORDER. INVERTED NNW-SSE SURFACE TROUGH OVER WESTERN QUEBEC IS EXPECTED TO BACK OVER THE COURSE OF THE DAY...ALLOWING LOW LEVEL WINDS TO SHIFT TO MORE OF A NW DIRECTION ACROSS THE CWA. ALTHOUGH INVERSION HEIGHTS WILL SLIGHTLY INCREASE WITH ONGOING LOW/MID-LEVEL COLD ADVECTION...BACKING WIND PROFILES AND ONLY MODERATE MOISTURE (900-700MB RH 45-60 PCT) MEANS ANY LAKE EFFECT SHOWERS WILL REMAIN SCATTERED IN NATURE. REGARDLESS...A FAIR AMOUNT OF STRATO-CU WILL DEVELOP THIS AFTERNOON WITH DEEP LAYER CYCLONIC FLOW AND THERMAL TROUGHING...SO A DAY SIMILAR TO YESTERDAY LOOKS REASONABLE. HIGHS IN THE MID 40S TO LOW 50S LOOKS GOOD. TONIGHT...VORT LOBE CURRENTLY ON THE NORTHERN PERIPHERY OF THE UPPER LOW WILL ROTATE AROUND ITS WESTERN FLANK AND CLIP THE NE CWA. DEEPER MOISTURE (900-700MB RH INCREASES GREATER THAN 70 PCT) WILL SPREAD ACROSS EASTERN UPPER AND TIP OF THE MITT WHILE 850MB TEMPS REMAIN IN THE MINUS 3-4 RANGE. SHOULD THEREFORE SEE AN UPTICK IN SHOWER ACTIVITY ACROSS EASTERN UPPER DURING THE EVENING WHICH SHOULD REMAIN STEADY OVERNIGHT. SHOWERS ACROSS NORTHERN LOWER SHOULD REMAIN MORE SPOTTY IN NATURE WITHIN WNW FLOW REGIMES AS THE DEEPER MOISTURE JUST DOES NOT MAKE IT SOUTH OF M68. WINDS INCREASE AS THE PRESSURE GRADIENT TIGHTENS IN RESPONSE TO THE VORT LOBE. 850MB WINDS INCREASE TO 35 KTS OVERNIGHT AND WITH COASTAL CONVERGENCE...GALE WARNINGS MAY BE NEEDED FOR NE LOWER. WILL LET DAY CREW CONTINUE TO ASSESS THE NEW DATA...AS ITS RIGHT ON THE EDGE. SATURDAY INTO SATURDAY NIGHT...UPPER LOW GRADUALLY PULLS AWAY TO THE EAST WHILE INCREASINGLY ANTICYCLONIC FLOW AND DRIER AIR MOVES IN. DEEPEST MOISTURE WILL RESIDE OVER EASTERN UPPER ON SATURDAY...AND THEREFORE WILL SEE THE BEST CHANCE OF SHOWERS AS LOW LEVEL WINDS REMAIN STEADY IN THE NW DIRECTION. 850MB TEMPS MODERATE SOMEWHAT TO NEAR 0C...BUT WITH DELTA T/S REMAINING IN THE MID TEENS...STILL PLENTY COLD FOR LAKE EFFECT SHOWER ACTIVITY WITHIN THE NW FAVORED FLOW. BELIEVE LINGERING SHOWERS ACROSS NW LOWER WILL DISSIPATE DURING THE AFTERNOON AS DRIER AIR AND DIURNAL DISRUPTION TAKES ITS TOLL. HOWEVER...IT WILL TAKE UNTIL OVERNIGHT FOR THE DRIER AIR TO MOVE INTO EASTERN UPPER. MPC SUNDAY THROUGH TUESDAY...BLOCKED MID LEVEL TROUGH PATTERN (FEATURING CONTRA-ROTATING UPPER LOWS) THAT HAS DOMINATED THE GREAT LAKES REGION OVER THE LAST FEW DAYS STILL PROJECTED TO PULL OUT INTO THE ATLANTIC BY THE END OF THE WEEKEND...REPLACED BY MID LEVEL RIDGING AND A MODEST WARM-UP FOR SUNDAY. THIS HAS BEEN A PERSISTENT IDEA WITH THE MODEL GUIDANCE OVER THE LAST FEW DAYS LEADING TO FAIRLY HIGH CONFIDENCE IN A DRY FORECAST FEATURING PARTLY-MOSTLY SUNNY SKIES TO WRAP UP THE WEEKEND. SO...VERY LITTLE CHANGES ANTICIPATED TO THE GOING SUNDAY FORECAST. BIGGER FORECAST TROUBLES MATERIALIZE FOR EARLY NEXT WEEK HOWEVER. SPECIFICALLY...THE DEGREE OF PHASING THAT MAY OCCUR OVER THE UPPER MIDWEST/WESTERN GREAT LAKES BETWEEN A SRN STREAM UPPER LOW MIGRATING OUT OF THE PLAINS AND NRN STREAM SHORT WAVE COMING OUT OF CENTRAL CANADA. PREVIOUS GFS SOLUTIONS WERE THE MOST BULLISH WITH THIS IDEA AND LARGELY IGNORED IN FAVOR OF A WEAKER ECMWF. HOWEVER...12/00Z ECMWF DATA GOING THE WAY OF THE GFS WITH STRONGER PHASING INDICATED AND SUGGESTS BAND OF FRONTOGENETICALLY INDUCED PRECIP DEVELOPING AND SPREADING INTO THE STATE MONDAY OR MONDAY NIGHT (AGAIN SIMILAR TO THE GFS). OBVIOUSLY FORECAST CONFIDENCE IS NOT GREAT. BUT IN LIGHT OF THE LATEST ECMWF DO FEEL COMPELLED TO ADD POPS TO AT LEAST THE MONDAY AND MONDAY NIGHT PORTION OF THE FORECAST FOR NOW. IF THIS SCENARIO HOLDS PRECIP CHANCES WILL NEED TO BE FURTHER EXTENDED THROUGH TUESDAY. BUT AT THIS POINT DO NOT WANT TO COMPLETELY PLOW OVER THE GOING FORECAST...AND WILL KEEP TUESDAY DRY. ADAM && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 412 AM EDT FRI OCT 12 2007 .DISCUSSION...LATEST SURFACE/RUC ANALYSIS AND IR/WV/RADAR IMAGERY SHOW DUAL UPPER LEVEL LOWS...ONE OVER THE CHESAPEAKE BAY AND ANOTHER OVER THE ONTARIO/QUEBEC BORDER. WEAK BACKDOOR SURFACE TROUGH PROGRESSING ACROSS THE CWA WITH SOME CLEARING BEHIND THE TROUGH OVER EASTERN UPPER EAST OF I-75 AND TIP OF THE MITT AS WINDS SHIFT TO THE NORTHEAST (DOWNSLOPING)...WHILE LAKE EFFECT RAIN SHOWERS CONTINUE DOWN GRAND TRAVERSE BAY AND ALONG THE LAKE HURON COASTLINE. 850MB TEMPS APPEAR TO HAVE STABILIZED AROUND THE -3C ISOTHERM...WHILE COLD ADVECTION IS OCCURRING IN THE MID-LEVELS (INCREASING INVERSION HEIGHTS) AS THE UPPER LOW TO THE NORTH DRIFTS SLOWLY SOUTH. MAIN FORECAST CONCERNS OVER THE NEXT 24 HOURS REVOLVE AROUND PRECIP CHANCES WITH LINGERING UPPER LOW TO THE NE OF THE AREA. TODAY...UPPER LOW WILL REMAIN NEARLY STATIONARY (MAYBE A SLIGHT DRIFT TO THE SW) ALONG THE ONTARIO/QUEBEC BORDER. INVERTED NNW-SSE SURFACE TROUGH OVER WESTERN QUEBEC IS EXPECTED TO BACK OVER THE COURSE OF THE DAY...ALLOWING LOW LEVEL WINDS TO SHIFT TO MORE OF A NW DIRECTION ACROSS THE CWA. ALTHOUGH INVERSION HEIGHTS WILL SLIGHTLY INCREASE WITH ONGOING LOW/MID-LEVEL COLD ADVECTION...BACKING WIND PROFILES AND ONLY MODERATE MOISTURE (900-700MB RH 45-60 PCT) MEANS ANY LAKE EFFECT SHOWERS WILL REMAIN SCATTERED IN NATURE. REGARDLESS...A FAIR AMOUNT OF STRATO-CU WILL DEVELOP THIS AFTERNOON WITH DEEP LAYER CYCLONIC FLOW AND THERMAL TROUGHING...SO A DAY SIMILAR TO YESTERDAY LOOKS REASONABLE. HIGHS IN THE MID 40S TO LOW 50S LOOKS GOOD. TONIGHT...VORT LOBE CURRENTLY ON THE NORTHERN PERIPHERY OF THE UPPER LOW WILL ROTATE AROUND ITS WESTERN FLANK AND CLIP THE NE CWA. DEEPER MOISTURE (900-700MB RH INCREASES GREATER THAN 70 PCT) WILL SPREAD ACROSS EASTERN UPPER AND TIP OF THE MITT WHILE 850MB TEMPS REMAIN IN THE MINUS 3-4 RANGE. SHOULD THEREFORE SEE AN UPTICK IN SHOWER ACTIVITY ACROSS EASTERN UPPER DURING THE EVENING WHICH SHOULD REMAIN STEADY OVERNIGHT. SHOWERS ACROSS NORTHERN LOWER SHOULD REMAIN MORE SPOTTY IN NATURE WITHIN WNW FLOW REGIMES AS THE DEEPER MOISTURE JUST DOES NOT MAKE IT SOUTH OF M68. WINDS INCREASE AS THE PRESSURE GRADIENT TIGHTENS IN RESPONSE TO THE VORT LOBE. 850MB WINDS INCREASE TO 35 KTS OVERNIGHT AND WITH COASTAL CONVERGENCE...GALE WARNINGS MAY BE NEEDED FOR NE LOWER. WILL LET DAY CREW CONTINUE TO ASSESS THE NEW DATA...AS ITS RIGHT ON THE EDGE. SATURDAY INTO SATURDAY NIGHT...UPPER LOW GRADUALLY PULLS AWAY TO THE EAST WHILE INCREASINGLY ANTICYCLONIC FLOW AND DRIER AIR MOVES IN. DEEPEST MOISTURE WILL RESIDE OVER EASTERN UPPER ON SATURDAY...AND THEREFORE WILL SEE THE BEST CHANCE OF SHOWERS AS LOW LEVEL WINDS REMAIN STEADY IN THE NW DIRECTION. 850MB TEMPS MODERATE SOMEWHAT TO NEAR 0C...BUT WITH DELTA T/S REMAINING IN THE MID TEENS...STILL PLENTY COLD FOR LAKE EFFECT SHOWER ACTIVITY WITHIN THE NW FAVORED FLOW. BELIEVE LINGERING SHOWERS ACROSS NW LOWER WILL DISSIPATE DURING THE AFTERNOON AS DRIER AIR AND DIURNAL DISRUPTION TAKES ITS TOLL. HOWEVER...IT WILL TAKE UNTIL OVERNIGHT FOR THE DRIER AIR TO MOVE INTO EASTERN UPPER. MPC SUNDAY THROUGH TUESDAY...BLOCKED MID LEVEL TROUGH PATTERN (FEATURING CONTRA-ROTATING UPPER LOWS) THAT HAS DOMINATED THE GREAT LAKES REGION OVER THE LAST FEW DAYS STILL PROJECTED TO PULL OUT INTO THE ATLANTIC BY THE END OF THE WEEKEND...REPLACED BY MID LEVEL RIDGING AND A MODEST WARM-UP FOR SUNDAY. THIS HAS BEEN A PERSISTENT IDEA WITH THE MODEL GUIDANCE OVER THE LAST FEW DAYS LEADING TO FAIRLY HIGH CONFIDENCE IN A DRY FORECAST FEATURING PARTLY-MOSTLY SUNNY SKIES TO WRAP UP THE WEEKEND. SO...VERY LITTLE CHANGES ANTICIPATED TO THE GOING SUNDAY FORECAST. BIGGER FORECAST TROUBLES MATERIALIZE FOR EARLY NEXT WEEK HOWEVER. SPECIFICALLY...THE DEGREE OF PHASING THAT MAY OCCUR OVER THE UPPER MIDWEST/WESTERN GREAT LAKES BETWEEN A SRN STREAM UPPER LOW MIGRATING OUT OF THE PLAINS AND NRN STREAM SHORT WAVE COMING OUT OF CENTRAL CANADA. PREVIOUS GFS SOLUTIONS WERE THE MOST BULLISH WITH THIS IDEA AND LARGELY IGNORED IN FAVOR OF A WEAKER ECMWF. HOWEVER...12/00Z ECMWF DATA GOING THE WAY OF THE GFS WITH STRONGER PHASING INDICATED AND SUGGESTS BAND OF FRONTOGENETICALLY INDUCED PRECIP DEVELOPING AND SPREADING INTO THE STATE MONDAY OR MONDAY NIGHT (AGAIN SIMILAR TO THE GFS). OBVIOUSLY FORECAST CONFIDENCE IS NOT GREAT. BUT IN LIGHT OF THE LATEST ECMWF DO FEEL COMPELLED TO ADD POPS TO AT LEAST THE MONDAY AND MONDAY NIGHT PORTION OF THE FORECAST FOR NOW. IF THIS SCENARIO HOLDS PRECIP CHANCES WILL NEED TO BE FURTHER EXTENDED THROUGH TUESDAY. BUT AT THIS POINT DO NOT WANT TO COMPLETELY PLOW OVER THE GOING FORECAST...AND WILL KEEP TUESDAY DRY. ADAM && .AVIATION (06Z ISSUANCE)...INSTABILITY SHOWERS WILL BE THE RULE THROUGH THE DAY FRIDAY...AUGMENTED BY DEEPER MOISTURE ROTATING INTO NORTHERN MI FRIDAY NIGHT. EXPECTING MAINLY VFR CONDITIONS OUTSIDE OF RAIN SHOWERS WHERE OCCASIONAL MVFR CEILINGS ANTICIPATED. JPB && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 444 AM CDT FRI OCT 12 2007 .DISCUSSION... WEAK SHORT WAVE ACCOUNTING FOR SCT LIGHT -RW ACTIVITY OVER PORTIONS OF W CENTRAL WI AND NE MN CWA PRIOR TO DAWN. USED GFS40 AS MODEL OF CHOICE DUE TO ITS DEPICTION OF 50H LOW JUST WEST OF N CA PER VAPOR LOOP...AND ITS PAINTING OF CURRENT SCT CONVECTIVE ACTIVITY AS NOTED ABOVE. PERSISTENT MID LEVEL CLOUD DECK WILL BE TOUGH TO BUDGE THIS DAY...UNTIL PASSAGE OF 70H TROF LATE THIS AFTERNOON. A SHORT TERM REPRIEVE OF MOSTLY CLOUDY SKY DECK WILL COMMENCE THIS EVENING...AND LAST INTO SATURDAY MORNING...AHEAD OF NEXT SURFACE WAVE BREWING OVER OK PANHANDLE. 50H TROF OVER WEST COAST WILL DIG SIGNIFICANTLY OVER NEXT 36 TO 48 HOURS...AS SURFACE LOW DEEPENS ABOVE WESTERN KS. ADDITIONAL DEEPENING WILL OCCUR ON SATURDAY NIGHT...AS CUT OFF 50H LOW DEVELOPS TO ITS LEE OVER CENTRAL CO. 850MB MOISTURE FLUX CONVERGENCE ...850MB THETA E ADVECTION...AND 305K ISENTROPI ANAL ALL POINT TO CONVECTION BEGINNING OVER FAR SW CWA SAT EVE AND THEN QUICKLY DEVELOPING OVER REMAINDER OF SAME BY DAWN ON SUNDAY. LOOK FOR MAINLY SHOWERS WITH ISOLATED TSTMS WITH TT`S IN THE MID 40S ACRSS MUCH OF S HALF OF FA FOR MUCH OF SUNDAY. SIX TO SEVEN G/KG SPECIFIC HUMIDITY VALUES COMBINED WITH SEVERAL STRONG 250MB DIVERGENCE COUPLETS COULD BRING ONE TO ONE AND ONE HALF INCHES OF RAIN SOUTH OF SPRINGFIELD TO NEW PRAGUE TO BLOOMER LINE BEFORE INVERTED TROUGH AHEAD OF SFC SYSTEM TRACKING EAST ACROSS MO FINALLY EXITS OUR NECK OF THE WOODS BY SUNDAY EVENING. OF COURSE RESIDUAL LIGHT -RW ACTIVITY SHOULD BE ANTICIPATED ACROSS MUCH OF FA RIGHT INTO TUESDAY AS ENERGY ROTATES AROUND CLOSED 50H LOW SPINNING LIKE A TOP ABOVE LAKE SUPERIOR. CLOSED MID LEVEL LOW FINALLY PUTS ON ITS WALKING SHOES ON WED AS IT MARCHES INTO WESTERN QUEBEC...AND LEAVES THE DOOR OPEN FOR NEXT SURFACE CYCLOGENTIC DEVELOPMENT OVER CENTRAL AND NORTHERN GREAT PLAINS BY WEDNESDAY EVENING. DIFFERENCE THIS GO AROUND WILL BE A MUCH DEEPER LOW PRESSURE AREA WHICH IS PROGGED TO TRACK MUCH FURTHERN NORTH FROM CENTRAL IA TO S WI DURING COURSE OF THU NIGHT. LUCKILY 50H THICKNESS VALUES WILL COOPERATE...FOR ANOTHER ALL LIQUID PRECIPITATION EVENT ENDING BY FRIDAY AFTERNOON. && && .PREV DISCUSSION... /ISSUED 1048 PM CDT THU OCT 11 2007/ AVIATION... /06Z TAF ISSUANCE/ SHORT WAVE PUSHING INTO FAR WESTERN MN ATTM WITH SCATTERED SHOWERS IN ADVANCE. EVEN A FEW TSTMS SHOWING UP FROM KRWF TO KAXN WITH RUC BEST LI`S AT OR BELOW ZERO. FEATURE WEAKENS OVER THE NEXT 6 HOURS WHILE HEADING INTO EASTERN MN. MENTIONED VCSH FOR KSTC...KMSP AND KRNH. MVFR CIGS BASICALLY DOWN TO KAXN AND KSTC ATTM. SOME IMPROVEMENT TO VFR POSSIBLE AS THE SHORT WAVE MOVES THROUGH. OVERALL...EXPECT CEILINGS TO REDEVELOP IN THE CLEAR AREAS OF EAST CENTRAL MN AND WEST CENTRAL MN OVERNIGHT WITH CEILINGS A LITTLE EITHER SIDE OF 3000 FEET BY MORNING. STILL STUCK WITH LOW LEVEL RIDGE AXIS OVER US ON FRIDAY ALONG WITH SOME WAA. EXPECT EXTENSIVE VFR LOW CEILINGS TO CONTINUE. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ AJZ/KAT mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 835 PM CDT FRI OCT 13 2007 .UPDATE... RADIATIONAL COOLING WILL NOT BE AS GOOD AS LAST NIGHT WITH THE CENTER OF HIGH PRESSURE OVER THE APPALACHIANS. MODELS AND RUC SHOWS SOME SOUTHERLY WINDS WILL COME ACROSS THE REGION IN THE LOWER LEVELS... WHICH WILL HELP TO SLOW DOWN THE RADIATIONAL COOLING SOME. WINDS WILL BE RATHER LIGHT ACROSS THE SURFACE UNDER CLEAR SKIES. EXPECT THE BEST RADIATIONAL COOLING TO BE IN THE EAST...WHERE SURFACE HIGH PRESSURE WILL HAVE A BETTER INFLUENCE. FALLING TEMPERATURES ARE RUNNING A LITTLE SLOWER THAN EXPECTED. SO WILL MAKE SLIGHT HOURLY ADJUSTMENTS ON THE GRIDS. CURRENT FORECAST LOWS APPEARS TO BE ON TRACK WITH MIDDLE 40S EAST TO AROUND 50 WEST. A COOL START TOMORROW SHOULD BE FOLLOWED BY RAPID WARMUP WITH CONDITIONS SETTING UP WELL FOR SOME LOCATIONS IN THE EAST TO EXPERIENCE A RARE 40 DEGREE DIURNAL RANGE IN TEMPERATURES BY TOMORROW AFTERNOON./17/ && .AVIATION...VFR CONDITIONS WILL PREVAIL OVER MOST OF THE AREA THROUGH THE PERIOD...BUT SOME FOG MAY BRING MVFR CONDITIONS TO GLH DURING THE EARLY MORNING HOURS. IT SHOULD BURN OFF BEFORE 14Z./17/ && .PREVIOUS DISCUSSION...305 PM CDT SAT OCT 13 2007 .SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT...HIGH PRESSURE AT THE SURFACE AND ALOFT WILL PREVAIL TONIGHT INTO SUNDAY. THE SURFACE RIDGE LOCATED OVER THE OHIO VALLEY WILL SHIFT A LITTLE TO THE EAST ON SUNDAY AND THIS WILL ALLOW OUR SURFACE FLOW TO BECOME A LITTLE MORE SOUTHEASTERLY DURING THE DAY. TEMPERATURES AND HUMIDITIES WILL BE SLIGHTLY HIGHER ON SUNDAY WITH THE SOUTHEAST FLOW. THE SURFACE RIDGE WILL SHIFT TO THE EAST COAST LATE SUNDAY AND THE SOUTHEAST FLOW WILL BECOME STRONGER SUNDAY NIGHT INTO MONDAY AND THIS WILL ALLOW OVERNIGHT LOWS TO BE AROUND 10 DEGREES WARMER THAN TONIGHT. STUCK CLOSE TO GUIDANCE...BUT DID CUT BELOW FOR THE USUAL COOLER SPOTS IN THE EAST BOTH NIGHTS FOR OVERNIGHT LOWS./15/ .LONG TERM...LONG TERM DISCUSSION... MONDAY THROUGH NEXT SATURDAY... UPDATE: AFTER LOOKING AT THE LATEST GLOBAL MODEL GUIDANCE...WE STILL EXPECT A COUPLE OF STORM SYSTEMS TO AFFECT THE FORECAST AREA NEXT WEEK AS DESCRIBED IN THE PREVIOUS FORECAST DISCUSSION. HOWEVER...THERE WERE SOME CHANGES MADE TO THE MID WEEK FORECAST GRIDS. MODELS HINT THAT A DECENT TROUGH-TO-RIDGE PATTERN WILL DEVELOP ACROSS THE CNTRL/ERN CONUS...AND THIS WOULD SUPPORT THE STALLING OUT OF THE FIRST SYSTEM AS FORECASTED PREVIOUSLY. THE FIRST FRONT WILL WEAKEN AS IT STALLS OVER THE AREA...BUT WITH THE PROSPECT FOR PERTURBED MID LEVEL SW FLOW AND VERY MOIST AIR OVER THE GULF POISED TO SURGE NWD...DID NOT FEEL COMFORTABLE WITH DRY WX FOR TUES NIGHT/WED AND RAISED POPS THERE FOR THOSE PERIODS. HEAVY RAINFALL MAY BE A CONCERN SHOULD THE 00Z ECMWF VERIFY...BUT WILL LEAVE OUT MENTION OF HEAVY RAIN AT THIS POINT AS DEEPER MOISTURE IS STILL EXPECTED TO BE TRANSPORTED MAINLY TO OUR EAST. INSTABILITY IS NOT ALL THAT GREAT INITIALLY WITH RELATIVELY HIGH MID LEVEL HEIGHTS STILL IN PLACE...BUT WE`LL NEED TO WATCH FOR GREATER AMPLIFICATION OF THE SHORTWAVE TROUGHS LATER IN THE WEEK FOR THE POTENTIAL FOR STRONG CONVECTION. /EC/ PREVIOUS LONG TERM DISCUSSION... AT LEAST TWO POTENTIALLY SUBSTANTIAL SYSTEMS APPEAR TO IMPACT THE MEDIUM RANGE PERIOD. LATEST GFS AND ENSEMBLES SUPPORT THE FIRST SHORTWAVE TROUGH CROSSING OUR REGION ON TUESDAY. THIS TROUGH EJECTS FROM THE SRN ROCKIES ON MONDAY HEADING TOWARD THE WRN GREAT LAKES AND WEAKENS AS IT DRAGS A PACIFIC COLD FRONT INTO THE LOWER MS VALLEY TUESDAY NIGHT. THE INTERACTION OF THIS FRONT WITH DEEPER TROPICAL MOISTURE STILL REMAINS DOUBTFUL AS THE BOUNDARY APPEARS TO PASS BEFORE THE RICHER PWAT AIR OF 2+ INCHES SPREADS NWD. WILL KEEP BEST POPS IN PLACE ON TUESDAY NEAR 50/50 AS THE EXACT TIMING COULD SLIP PLUS/MINUS 12 HOURS. EVEN SO...THE AIR MASS INSTABILITY REMAINS ON THE TAME SIDE FOR NOW WITH MID LEVEL LAPSE RATES OF 4.5-5C...MLCAPES BELOW 400J/KG...850MB FLOW OF 25KTS AND K INDEXES IN THE L30S. BY WEDNESDAY...THE LOW LEVEL BOUNDARY SHOULD BE STALLING FROM THE GULF ACROSS THE SERN STATES AWAITING A MORE POTENT MID LEVEL SHORTWAVE APPROACHING ON FRIDAY. MUCH LESS CONFIDENCE IN THE TIMING AND STRENGTH OF THIS SYSTEM LATE NEXT WEEK BUT AGREEMENTS CENTER ON IT BEING QUITE A BIT STRONGER THAN THE EARLY WEEK STORM. ON FRIDAY AND FRIDAY NIGHT...BETTER MOISTURE AND INSTABILITY SHOULD BE AVAILABLE ALONG WITH HIGHER WIND SHEAR POTENTIAL SO WE WILL BE MONITORING CLOSELY FOR FUTURE MODEL TRENDS. FOR INSTANCE...CURRENT 00Z GFS SHOWING 70-100KT 500MB WINDS DIVING THROUGH THE ARKLATEX INTO NRN MS BY NEXT SATURDAY MORNING WHILE 850MB WINDS STAY BELOW 30KTS. FOR NOW WE ARE DISCOUNTING THE FASTER ECMWF WHICH HAS BEEN LESS CONSISTENT IN HANDLING THE SYSTEM DURING PAST 3 CYCLES. OTHERWISE...TEMPERATURES WILL HOLD ABOVE CLIMATOLOGY MOST OF NEXT WEEK WITH HIGHS GENERALLY IN THE LOW-MID 80S AND OVERNIGHT LOWS IN THE U50S AND 60S AS ZONAL UPPER FLOW PATTERN SENDS DRY PACIFIC AIR EWD./40/ && .AVIATION...VFR CONDITIONS WILL PREVAIL OVER MOST OF THE AREA THROUGH THE PERIOD...BUT SOME FOG MAY BRING MVFR CONDITIONS TO GLH DURING THE EARLY MORNING HOURS./15/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 80 47 84 60 / 0 0 0 1 MERIDIAN 80 44 84 51 / 0 0 0 1 VICKSBURG 80 49 84 60 / 0 0 0 2 HATTIESBURG 81 45 84 57 / 0 0 0 4 NATCHEZ 78 52 81 61 / 0 0 0 2 GREENVILLE 81 51 84 56 / 0 0 0 2 GREENWOOD 81 49 85 57 / 0 0 0 2 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ 15/43/15 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 646 AM CDT SAT OCT 13 2007 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... /ISSUED 430 AM CDT SAT OCT 13 2007/ IMPRESSIVE LOOKING ISENTROPIC LIFT ON THE 300-305K SURFACES COMBINED WITH AN INCREASING SOUTHERLY LOW LEVEL JET HAS RESULTED IN A VERY EFFICIENT RAIN MAKER FROM NORTH CENTRAL/NORTHEAST KS INTO NORTHWEST AND WEST CENTRAL MO. PROFILER NETWORK SHOWS THE 850MB WINDS HAVE VEERED AND INCREASED TO 50-55KT OVER THE CENTRAL PLAINS SINCE MIDNIGHT. THIS JET AXIS IS RUNNING OVER THE TOP OF AN EAST-WEST WARM FRONT WHICH LIES ACROSS SOUTHERN SECTIONS OF KS AND MO. A SOUTHWESTERLY MID LEVEL FLOW EMANATING FROM A DEEPENING UPPER WAVE MOVING INTO THE DESERT SOUTHWEST CONTINUES TO PULL MOISTURE RICH PACIFIC AIR EASTWARD. ELEMENTS APPEAR TO COME TOGETHER OVER THE WEST CENTRAL PORTION OF THE CWA THIS MORNING FOR A HEAVY RAIN THREAT. FFG VALUES IN THIS AREA ARE BETWEEN 1.5 AND 2 INCHES/3 HOURS. ALTHOUGH THE STORMS ARE MOVING ALONG ON RADAR THE UPSTREAM CONVECTION FROM CENTRAL INTO EAST CENTRAL KS IS FILLING IN SO WAVES OF STORMS ARE ANTICIPATED THROUGH MID MORNING OVER THE WEST CENTRAL CWA BEFORE THE ISENTROPIC LIFT SHIFTS NORTHEAST INTO NORTHERN MO. BY LATE MORNING AND EARLY AFTERNOON THE LOW LEVEL JET IS EXPECTED TO WEAKEN AND BEGIN TO REFORM BACK TO THE WEST IN RESPONSE TO FALLING HEIGHTS AS THE PRIMARY STORM SYSTEM MOVES INTO THE CENTRAL ROCKIES. HAVE MENTIONED HEAVY RAINS IN THE ZFP AND WILL HIT IN THE HWO. THE AFOREMENTIONED WARM FRONT OVER SOUTHERN MO IS EXPECTED TO LIFT NORTH LATER TODAY...POSSIBLY MAKING IT TO JUST SOUTH OF THE MO RIVER BY LATE AFTERNOON. BELIEVE THE MORNING CONVECTION AND FALLING HEIGHTS OVER HIGH PLAINS WILL KEEP THE WARM FRONT FROM SURGING NORTH TILL LATER THIS EVENING. MAX TEMPERATURES WILL BE PROBLEMATIC DUE TO THIS AND THE EXTENSIVE MORNING CONVECTION. PRECIPITATION CHANCES SHOULD BE CONFINED TO FAR NORTHERN COUNTIES THIS EVENING AND FAR NORTHWEST COUNTIES OVERNIGHT. WILL COVER REST OF THE CWA WITH ONLY SLIGHT CHANCES AS WE AWAIT THE ARRIVAL OF THE DEEP UPPER TROUGH. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE NEXT SYSTEM WHICH IS MOVING INTO THE DESERT SOUTHWEST. EVEN THOUGH THE MODELS HAVE BEEN SLOWING THIS SYSTEM DOWN DUE TO IT DEEPENING AND CLOSING OFF THEY STILL MAY BE A BIT TOO FAST. SO FOR SUNDAY BELIEVE ONLY FAR WESTERN CWA RUNS THE RISK OF CONVECTION. JUXTAPOSITION OF INSTABILITY AXIS AND 0-6KM BULK SHEAR SUGGESTS SEVERE THREAT SHOULD BE WEST OF THE CWA EXCEPT FOR POSSIBLY THE NORTHWEST TIP BUT TIMING OF BETTER UPPER DYNAMICS ARRIVE AFTER DARK ON SUNDAY SO SEVERE THREAT LOOKS MUTED AT THIS TIME. LIKELY POPS STILL LOOK IN ORDER FOR SUNDAY EVENING OVER ALL BUT THE FAR EASTERN CWA AND OVER ALL BUT THE EXTREME WESTERN COUNTIES ON MONDAY. MAX TEMPERATURES WILL AGAIN BE A CHALLENGE ON MONDAY DUE TO THE PRECIPITATION AND LOCATION OF THE WARM SECTOR. MJ && .AVIATION... FAIRLY SOLID RAIN SHIELD EXTENDING FROM EASTERN KANSAS THROUGH MOST OF NORTHERN MISSOURI WITH EMBEDDED THUNDERSTORMS MAINLY CONCENTRATED ACROSS EASTERN KANSAS AND WESTERN MISSOURI. BACK EDGE OF THUNDERSTORM ACTIVITY NOW MOVING ACROSS A SENECA TO TOPEKA TO COLONY KANSAS LINE WITH THE MORE ROBUST THUNDERSTORM ACTIVITY ALONG THIS BACK EDGE. ROUGH TIMING BRINGS THE BACK LINE OF SHOWER/THUNDERSTORM ACTIVITY ACROSS THE TAF SITES CLOSE TO 15-16Z. THEREFORE...KEPT MENTION OF TSRA THROUGH THIS TIME FRAME...TAPERING OFF THE VC MENTION AFTER 15-16Z. MAY SEE SOME DECENT RAINFALL AS THE LINE MOVES ACROSS THE TERMINALS. LATEST RUC SHOWS BEST ISENTROPIC LIFT TO MOVE NORTH OF THE TERMINALS LIKELY ENDING THE RAIN THREAT BY THE AFTERNOON HOURS. KEPT CLOUD COVER PREVALENT THROUGH THE AFTERNOON HOURS WITH ADDITIONAL CLOUD COVER NOTED ACROSS THE HIGH PLAINS STREAMING EASTWARD THIS MORNING. DEROCHE && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 430 AM CDT SAT OCT 13 2007 .DISCUSSION... IMPRESSIVE LOOKING ISENTROPIC LIFT ON THE 300-305K SURFACES COMBINED WITH AN INCREASING SOUTHERLY LOW LEVEL JET HAS RESULTED IN A VERY EFFICIENT RAIN MAKER FROM NORTH CENTRAL/NORTHEAST KS INTO NORTHWEST AND WEST CENTRAL MO. PROFILER NETWORK SHOWS THE 850MB WINDS HAVE VEERED AND INCREASED TO 50-55KT OVER THE CENTRAL PLAINS SINCE MIDNIGHT. THIS JET AXIS IS RUNNING OVER THE TOP OF AN EAST-WEST WARM FRONT WHICH LIES ACROSS SOUTHERN SECTIONS OF KS AND MO. A SOUTHWESTERLY MID LEVEL FLOW EMANATING FROM A DEEPENING UPPER WAVE MOVING INTO THE DESERT SOUTHWEST CONTINUES TO PULL MOISTURE RICH PACIFIC AIR EASTWARD. ELEMENTS APPEAR TO COME TOGETHER OVER THE WEST CENTRAL PORTION OF THE CWA THIS MORNING FOR A HEAVY RAIN THREAT. FFG VALUES IN THIS AREA ARE BETWEEN 1.5 AND 2 INCHES/3 HOURS. ALTHOUGH THE STORMS ARE MOVING ALONG ON RADAR THE UPSTREAM CONVECTION FROM CENTRAL INTO EAST CENTRAL KS IS FILLING IN SO WAVES OF STORMS ARE ANTICIPATED THROUGH MID MORNING OVER THE WEST CENTRAL CWA BEFORE THE ISENTROPIC LIFT SHIFTS NORTHEAST INTO NORTHERN MO. BY LATE MORNING AND EARLY AFTERNOON THE LOW LEVEL JET IS EXPECTED TO WEAKEN AND BEGIN TO REFORM BACK TO THE WEST IN RESPONSE TO FALLING HEIGHTS AS THE PRIMARY STORM SYSTEM MOVES INTO THE CENTRAL ROCKIES. HAVE MENTIONED HEAVY RAINS IN THE ZFP AND WILL HIT IN THE HWO. THE AFOREMENTIONED WARM FRONT OVER SOUTHERN MO IS EXPECTED TO LIFT NORTH LATER TODAY...POSSIBLY MAKING IT TO JUST SOUTH OF THE MO RIVER BY LATE AFTERNOON. BELIEVE THE MORNING CONVECTION AND FALLING HEIGHTS OVER HIGH PLAINS WILL KEEP THE WARM FRONT FROM SURGING NORTH TILL LATER THIS EVENING. MAX TEMPERATURES WILL BE PROBLEMATIC DUE TO THIS AND THE EXTENSIVE MORNING CONVECTION. PRECIPITATION CHANCES SHOULD BE CONFINED TO FAR NORTHERN COUNTIES THIS EVENING AND FAR NORTHWEST COUNTIES OVERNIGHT. WILL COVER REST OF THE CWA WITH ONLY SLIGHT CHANCES AS WE AWAIT THE ARRIVAL OF THE DEEP UPPER TROUGH. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH THE NEXT SYSTEM WHICH IS MOVING INTO THE DESERT SOUTHWEST. EVEN THOUGH THE MODELS HAVE BEEN SLOWING THIS SYSTEM DOWN DUE TO IT DEEPENING AND CLOSING OFF THEY STILL MAY BE A BIT TOO FAST. SO FOR SUNDAY BELIEVE ONLY FAR WESTERN CWA RUNS THE RISK OF CONVECTION. JUXTAPOSITION OF INSTABILITY AXIS AND 0-6KM BULK SHEAR SUGGESTS SEVERE THREAT SHOULD BE WEST OF THE CWA EXCEPT FOR POSSIBLY THE NORTHWEST TIP BUT TIMING OF BETTER UPPER DYNAMICS ARRIVE AFTER DARK ON SUNDAY SO SEVERE THREAT LOOKS MUTED AT THIS TIME. LIKELY POPS STILL LOOK IN ORDER FOR SUNDAY EVENING OVER ALL BUT THE FAR EASTERN CWA AND OVER ALL BUT THE EXTREME WESTERN COUNTIES ON MONDAY. MAX TEMPERATURES WILL AGAIN BE A CHALLENGE ON MONDAY DUE TO THE PRECIPITATION AND LOCATION OF THE WARM SECTOR. MJ && .AVIATION... FOR THE 06Z TAFS...GOING MORE WITH THE RUC SOLUTION OF INCREASING ISENTROPIC LIFT ACROSS THE TAF SITES OVERNIGHT. 03Z RUC SHOWING BEST LIFT ON THE 302K SURFACE BECOMING CONCENTRATED ACROSS THE TAF SITES TOWARD 12Z AND CONTINUING THROUGH 15Z. THUS WILL START OFF WITH JUST VCSH AND A TEMPO TSRA THEN GO A CATEGORICAL SHRA AND STILL A TEMPO FOR HEAVIER TSRA BY 11Z. WILL PULL OUT MENTION OF ANY PRECIPITATION FOR THE AFTERNOON PERIOD. TOO MUCH UNCERTAINTY ON WHERE THE WARM FRONT MAY RESIDE BY THAT TIME AFTER MORNING CONVECTION. ALSO TAF SITES MAY BE UNDER A LITTLE SUBSIDENCE BEHIND WEAK SHORT WAVE THAT WILL BE MOVING PAST THE AREA IN THE MORNING. PC && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1258 PM CDT FRI OCT 12 2007 ...UPDATED AVIATION... .DISCUSSION... /943 PM CDT FRI OCT 12 2007/ WILL BE INCREASING POPS ACROSS NORTHERN AND WESTERN AREAS TONIGHT TO REFLECT THE INCREASING PRECIPITATION COVERAGE OCCURRING. ISENTROPIC LIFT SHOULD CONTINUE TO SUPPORT THIS ACTIVITY OVERNIGHT...ESPECIALLY ACROSS NORTHEAST KANSAS AND SPREADING ACROSS NORTHERN MISSOURI. PC && .PREV DISCUSSION... /401 PM CDT FRI OCT 12 2007/ THE PLEASANT FALL WEATHER THAT WE HAVE BEEN EXPERIENCING OVER THE PAST FEW DAYS IS ABOUT TO GIVE WAY TO A MUCH MORE ACTIVE PATTERN WHERE RAIN WILL PERIODICALLY SWEEP THROUGH THE REGION. THE BIG PICTURE ON WATER VAPOR IMAGERY SHOWS A MODESTLY AMPLIFIED PROGRESSIVE PATTERN IN PLACE ACROSS THE CONUS. CENTRAL PLAINS ARE CURRENTLY UNDER THE INFLUENCE OF A RIDGE WHOSE AXIS IS STILL IN CENTRAL KANSAS. A LITTLE FARTHER WEST A SHORTWAVE IS MOVING THROUGH THE RIDGE AXIS. THIS WAVE WILL BE OF CRITICAL IMPORTANCE FOR TONIGHT AND SATURDAYS WEATHER. LOOKING STILL FARTHER TO THE WEST...A LARGER TROUGH CAN BE SEEN BEGINNING TO MAKE LANDFALL ACROSS THE NORTHERN CALIFORNIA COAST. THIS TROUGH IS ALREADY SPINNING UP INTO A LARGE CLOSED LOW. HOWEVER...THIS LOW IS NOT EXPECTED...OR FORECAST...TO STALL...BUT WILL STAY PROGRESSIVE WITH THE HELP OF THE STRONG WESTERLIES ACROSS THE NORTH PACIFIC. THE BROAD CONSENSUS IN THE MODELS INDICATE THAT THE LOW WILL EXIT THE ROCKIES SUNDAY NIGHT...MOVING INTO THE PLAINS THROUGH WESTERN NEBRASKA AND KANSAS. FOR TONIGHT...THE SHORTWAVE IN WEST NEBRASKA THIS AFTERNOON WILL CREST THE RIDGE AND MOVE THROUGH NORTHERN MISSOURI SATURDAY...JUST AHEAD OF THE RIDGE AXIS...WHICH WILL ALSO BE MOVING EAST AHEAD OF THE CUTOFF LOW WAY OUT WEST. STORMS DUE TO ISENTROPIC ASCENT ON THE 305K TO 310K SURFACES...IN ASSOCIATION WITH A 30KTS LOW LEVEL JET...HAVE BEEN PERCOLATING ALONG ALL DAY IN CENTRAL KANSAS. AS THE SHORTWAVE MOVES EAST THE FOCUS OF THE ISENTROPIC LIFT WILL ALSO SHIFT. HAVE SPED UP THE ONSET OF LIKELY POPS INTO THE NORTHWEST CORNER OF MISSOURI AND FAR NORTHEAST CORNER OF KANSAS. WIDESPREAD THUNDERSTORM ACTIVITY IS STILL NOT EXPECTED UNTIL AFTER MIDNIGHT...BUT CURRENT DEVELOPMENT FROM SOUTH CENTRAL NEBRASKA INTO NORTH CENTRAL KANSAS AGREES WITH THE SHORT RANGE MODELS WHICH INDICATE THAT THE STORMS WILL ARRIVE SOONER RATHER THAN LATER. GFS/NAM-WRF/ECMWF ALL INDICATE THAT AS THE SHORTWAVE MOVES ACROSS NORTHERN MISSOURI IT WILL IMPEDE THE PROGRESS OF A WARM FRONT THAT WAS PREVIOUSLY PROGGED TO LIFT NORTH ALL THE WAY THROUGH MISSOURI INTO IOWA DURING THE DAY SATURDAY. HAVE KEPT CHANCE POPS SPREAD ACROSS THE ENTIRE FORECAST AREA FOR THE DAYLIGHT HOURS OF SATURDAY AS A RESULT. ALSO ADJUSTED THE TEMPERATURE SPREAD ACROSS THE REGION AREA DUE TO CLOUD COVER AND PRECIPITATION. SATURDAY NIGHT AND SUNDAY...THE CHANCE POPS SHIFT NORTH ALONG WITH THE FRONT. HAVE TRIED TO CONFINE THE POPS CLOSE TO THE IOWA BORDER AS ISENTROPIC LIFT AND FRONTOGENIC FORCING BOTH LOOK TO BE FOCUSED TO OUR NORTH. POTENTIAL FOR STRONG STORMS WITH HEAVY RAIN CONTINUES TO LOOK OKAY...BUT SEVERE WEATHER IS STILL NOT LOOKING LIKELY. SHEAR PARAMETERS CONTINUE TO LOOK DECENT (0-6KM GREATER THAN 40KTS AT TIMES)...BUT INSTABILITY IS POOR AT BEST. YOU HAVE TO LOOK ABOVE H8 IN ORDER TO FIND LAPSE RATE GREATER THAN 6C/KM. SUNDAY NIGHT WILL SEE THE LOW BEGINNING TO MOVE INTO THE PLAINS. WARM AIR ADVECTION AHEAD OF THE ASSOCIATED COLD FRONT SHOULD SPARK STORMS FOR THE OVERNIGHT HOURS. DID NOT MAKE MANY ADJUSTMENTS IN THIS TIME FRAME AS THE GOING FORECAST STILL FITS WELL WITH THE LATEST MODEL ANALYSIS. SEVERE POTENTIAL IS STILL A LITTLE IFFY THOUGH AS INSTABILITY REMAINS ELEVATED THROUGH THE NIGHT. CUTTER EXTENDED (MONDAY THROUGH FRIDAY)... QUITE ACTIVE WEATHER PATTERN IS IN STORE THROUGHOUT NEXT WEEK. THE FORECAST AREA WILL CONTINUE TO EXPERIENCE THE EFFECTS OF THE CENTRAL CONUS LOW INTO MONDAY. THE UPPER LOW IS NOW EXPECTED TO SLOW AS IT PROGRESSES NORTHEAST ACROSS KANSAS AND NEBRASKA TOWARD IOWA. IN RESPONSE TO THE SLOWER UPPER TROUGH PROGRESSION...THE SURFACE TROUGH/COLD FRONT IS NOT EXPECTED TO ADVANCE EAST ACROSS THE FORECAST AREA UNTIL MONDAY AFTERNOON/MONDAY NIGHT. THE MEDIUM RANGE FORECAST MODELS ALSO INDICATE PRECIPITATION LINGERING BEHIND THE SURFACE LOW AND COLD FRONT MONDAY NIGHT AS A SECONDARY UPPER LOW MAY ROTATE IN BEHIND THE MAIN UPPER LOW AND PROVIDE ADDITIONAL ENERGY FOR FORCING. AS A RESULT...HAVE STRETCHED PRECIPITATION CHANCES THROUGH MONDAY NIGHT. FOLLOWING THE PASSAGE OF THE COLD FRONT ACROSS THE AREA AND THE EXIT OF THE UPPER SYSTEM...MEDIUM RANGE MODEL SPREAD INCREASES QUITE SIGNIFICANTLY. THEREFORE...THERE IS QUESTION AS TO HOW LONG THE BREAK IN PRECIPITATION WILL LAST BEFORE THE NEXT DISTURBANCE ARRIVES. LEANED MAINLY TOWARD THE GFS ENSEMBLE MEAN AND HAVE KEPT WEDNESDAY DRY FOR NOW...BUT THAT IS NOT WITH GREAT CONFIDENCE. YET ANOTHER UPPER TROUGH WILL ENTER THE PACIFIC STATES EARLY NEXT WEEK...WITH A PORTION OF IT CROSSING THE ROCKIES TOWARD THURSDAY. A SURFACE TROUGH WILL DEVELOP AHEAD OF THIS FEATURE AND BRING ANOTHER ROUND OF SHOWERS AND POSSIBLE THUNDERSTORMS TO THE AREA ON THURSDAY. THE MEDIUM RANGE MODELS AGREE ON THIS SORT OF FEATURE BUT DISAGREE ON ITS TIMING. FOR NOW HAVE MENTIONED A CHANCE OF PRECIPITATION ON THURSDAY WITH THE EXPECTATION THAT THE TIMING MAY NEED TO BE REFINED AT A LATER TIME. AS FOR TEMPERATURES...HAVE LOWERED THEM A COUPLE OF DEGREES OVERALL THROUGH MUCH OF THE EXTENDED FORECAST AFTER MONDAY. TEMPERATURES MAY NOT YET BE COOL ENOUGH AS THEY ARE STILL ABOVE THE NUMERICAL GUIDANCE NUMBERS FROM THE GFS/ENSEMBLE MEAN/HPC. STOFLET && .AVIATION... FOR THE 06Z TAFS...GOING MORE WITH THE RUC SOLUTION OF INCREASING ISENTROPIC LIFT ACROSS THE TAF SITES OVERNIGHT. 03Z RUC SHOWING BEST LIFT ON THE 302K SURFACE BECOMING CONCENTRATED ACROSS THE TAF SITES TOWARD 12Z AND CONTINUING THROUGH 15Z. THUS WILL START OFF WITH JUST VCSH AND A TEMPO TSRA THEN GO A CATEGORICAL SHRA AND STILL A TEMPO FOR HEAVIER TSRA BY 11Z. WILL PULL OUT MENTION OF ANY PRECIPITATION FOR THE AFTERNOON PERIOD. TOO MUCH UNCERTAINTY ON WHERE THE WARM FRONT MAY RESIDE BY THAT TIME AFTER MORNING CONVECTION. ALSO TAF SITES MAY BE UNDER A LITTLE SUBSIDENCE BEHIND WEAK SHORT WAVE THAT WILL BE MOVING PAST THE AREA IN THE MORNING. PC && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BILLINGS MT 251 PM MDT SAT OCT 13 2007 .SHORT TERM...VALID FOR SUN AND MON... MARGINALLY UNSTABLE AIRMASS OVER THE REGION THIS AFTERNOON AS A BROAD AREA OF LOW PRESSURE MOVES THROUGH THE WEST ANCHORED BY A LOW OVER UTAH. FORCING HAS BECOME WEAKER AS THE DAY PROGRESSES BUT ENOUGH BREAKS IN THE CLOUDS ARE DRIVING SOME INCREASE IN INSTABILITY ALONG WITH UPSLOPE FLOW CAUSING FAVORED AREAS FOR SHOWERS. SHOWERS TO THE SOUTH OF BILLINGS ARE SLOW MOVING AND NOT INCREASING IN INTENSITY AND SHOWERS NORTH AND WEST OF BILLINGS ARE NOT LONG LIVED. WITH DRIER AIR MOVING IN FROM THE NORTH AND WEST FEEL THAT THE SHOWERS ARE NOT GOING TO MOVE MUCH FOR THE EVENING SO HAVE ADJUSTED PRECIP TRENDS DOWNWARD WHICH IS A TREND SUPPORTED BY THE LATEST RUC WITH THE WRF LOOKING OVER DEVELOPED ON CONVECTION. THOUGHT ABOUT FOG IN THE FORECAST BUT COMBINATION OF CLOUD COVER IN THE SOUTH AND EAST AND DRIER AIR MOVING IN SHOULD LIMIT MOST OF THE FOG TO VALLEY BOTTOMS. UPPER LEVEL RIDGING SURGES INTO THE AREA ON SUNDAY AND BRINGS DRYING FOR THE AIRMASS BUT LOW LEVEL FLOW REMAINS EASTERLY SO WARMUP WITH SUNNIER SKIES WILL BE CAPPED BY UPSLOPISH FLOW. RIDGING LINGERS FOR MONDAY AS THE DEPARTING SYSTEM SLOWS OVER THE MIDWEST AND A STRONG FLOW ALOFT ACROSS THE PACIFIC ALLOWS ANOTHER TROUGH TO PUSH INTO THE PACIFIC NORTHWEST. THIS WILL BRING WARMING FOR MODNAY ESPECIALLY WITH A SWITCH TO SOUTHWEST WINDS BUT THE UPPER LEVEL FLOW WILL INDUCE PRESSURE FALLS OVER IDAHO AT THE SURFACE WHICH WILL KEEP PRESSURE GRADIENTS AND WINDS OVER THE AREA FAIRLY WEEK. BORSUM .LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT... NO MAJOR CHANGES TO EXTENDED FORECAST THIS AFTERNOON. MODELS CONTINUE TO BE IN GOOD AGREEMENT THROUGH MUST OF THE EXTENDED WITH GENERALLY MOIST WESTERLY FLOW ACROSS THE REGION. FOR TUESDAY...UPPER RIDGE MOVES EAST OF THE AREA BRINGING SOUTHWEST FLOW AND WARM TEMPERATURES TO THE AREA. TROUGH APPROACHING THE AREA FROM THE PACIFIC NORTHWEST AND LEFT SLIGHT CHANCE POPS IN THE MOUNTAINS AS MOISTURE AND ENERGY ROTATE NORTHWARD OUT OF THE TROUGH. BY WEDNESDAY TROUGH MOVES OVER FORECAST AREA BRINGING GREATEST CHANCES FOR PRECIP TO THE MOUNTAINS AND SOUTHERN ZONES AS BEST UPPER DIVERGENCE AND LIFT STAYS ACROSS NORTHERN WYOMING AND SOUTHERN MONTANA. LOWERED TEMPERATURES A COUPLE OF DEGREES WITH CLOUDS...PRECIP AND LOWERING THICKNESSES THROUGHOUT THE DAY. RAISED POPS A BIT IN THE CENTRAL AND SOUTHERN ZONES. IT SHOULD BE NOTED THAT THE GFS IS FLATTER WITH MORE WESTERLY FLOW WHILE THE ECMWF BRINGS ACROSS A MORE AMPLIFIED TROUGH WITH NORTHWEST FLOW ENHANCING PRECIPITATION AMOUNTS ACROSS THE ENTIRE FORECAST AREA SO TRENDS WILL NEED TO BE MONITORED FOR POSSIBLE CHANGES DURING THE WEDNESDAY MORNING INTO THURSDAY PERIOD. ON THURSDAY MODELS BEGIN TO DIFFER SOMEWHAT WITH THE GFS SETTING UP A WEST-NORTHWEST FLOW PATTERN ACROSS THE AREA AND THE ECMWF FORECASTING FLATTER WEST TO SOUTHWEST FLOW. EITHER WAY...PLENTY OF MOISTURE STAY OVER THE AREA WITH MODELS DEPICTING SHORTWAVE ENERGY MOVING THROUGH WITH BOTH SOLUTIONS TO GENERATE AT LEAST MOUNTAINS SHOWERS. HAVE LEFT POPS ALONE IN THE MOUNTAINS AND HAVE NEAR CLIMO POPS IN THE PLAINS FOR THURSDAY THROUGH SATURDAY. TEMPERATURES SHOULD STAY NEAR SEASONAL AVERAGES THROUGH THE END OF THE EXTENDED. STOPPKOTTE && .AVIATION... A LOW PRESSURE SYSTEM WILL CONTINUE TO MOVE OUT OF THE AREA THIS EVENING AND OVERNIGHT. WIDELY SCATTERED RAIN WILL STAY MAINLY EAST OF THE KBIL AREA AND SHOULD BEGIN TO DIMINISH OVERNIGHT. MVFR TO IFR CONDITIONS CAN BE EXPECTED IN THIS AREA THROUGH TONIGHT. CONDITIONS WILL BEGIN TO IMPROVE BY SUNDAY MORNING AS HIGH PRESSURE BUILDS BACK INTO THE AREA. ELSEWHERE...PARTLY CLOUDY SKIES AND VFR CONDITIONS WILL PREVAIL. STOPPKOTTE && .PRELIMINARY POINT TEMP/POPS... SUN MON TUE WED THU FRI SAT ----------------------------------------------------------- BIL 039/061 039/067 039/067 045/062 039/056 035/057 036/059 20/B 00/U 00/B 02/W 22/W 22/W 11/B LVM 035/060 038/065 038/063 040/056 035/052 036/053 036/055 10/B 00/U 00/B 33/W 43/W 22/W 22/R HDN 039/060 037/069 036/069 043/066 038/060 036/063 035/064 42/W 00/U 00/U 02/W 22/W 22/W 11/B MLS 040/060 040/066 039/068 040/065 037/061 036/061 037/063 41/B 00/U 00/U 02/W 22/W 21/B 11/B 4BQ 041/057 037/064 036/067 041/062 037/060 036/060 035/066 83/W 00/U 00/U 02/W 22/W 22/W 11/B BHK 039/056 037/061 036/062 038/062 037/058 034/056 035/061 52/W 00/U 00/U 02/W 22/W 21/B 11/B SHR 041/056 035/066 033/067 039/061 036/059 033/056 034/062 72/W 00/U 00/U 12/W 23/W 22/W 21/B && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 316 AM CDT FRI OCT 12 2007 .DISCUSSION... OVERALL DID NOT MAKE MANY CHANGES TO THE PREVIOUS FORECAST. THE MAIN CONCERNS ARE GOING TO BE TIMING THE BEST CHANCES FOR PCPN AND JUST HOW MUCH PCPN WILL OCCUR. LATEST WATER VAPOR IMAGERY LOOP SHOWED TWO CLOSED LOWS TO OUR EAST. ONE WAS DROPPING SOUTHWARD TOWARD THE GREAT LAKES AND THE OTHER WAS MOVING EAST THROUGH THE MID ATLANTIC STATES. CLOSED LOW OFF THE COAST OF CALIFORNIA IS MUCH MORE OF A CONCERN FOR OUR AREA. FAIRLY WEAK HEIGHT FALLS WERE NOTED OVER THE WESTERN U.S. LAST EVENING AT 500 MB FROM THE 00Z PLOT. SLIGHTLY STRONGER FALLS WERE SUGGESTED FROM THE LATEST RUC OUTPUT ENDING AT 06Z...UP TO 60 METER FALLS WERE SUGGESTED ALONG THE COAST. MAIN JET CORE (125 KTS) WAS STILL ON THE BACK SIDE OF THE TROUGH...SO SYSTEM SHOULD CONTINUE TO DIG SOUTHEASTWARD FOR A WHILE. IN THE PLAINS...WARMER AIR AND MOISTURE WERE WORKING NORTH AT 850 MB. THE DEWPOINT AT KOAX WAS ONLY 6 DEGREES C...BUT UPSTREAM IT WAS IN THE LOWER AND MID TEENS ACROSS TEXAS. HIGHS YESTERDAY WERE ONLY IN THE UPPER 50S AND LOWER 60S...BUT TODAY SHOULD BE WARMER. EXPECT HIGHS IN THE MID OR UPPER 60S NORTH...AND CLOSE TO 70 SOUTH. SHORTWAVE TROUGH OVER UTAH AND WESTERN COLORADO EARLY THIS MORNING SHOULD CONTINUE TO MOVE EAST AND INTERACT WITH MOISTURE STREAMING NORTH. DECIDED TO INCREASE AND EXPAND POPS JUST A LITTLE FOR TODAY FOR SOUTHEAST NEBRASKA AND SOUTHWEST IOWA. THE 00Z GFS SEEMED TO HAVE A DECENT HANDLE ON THINGS. ISENTROPIC LIFT IN THE 300 K TO 310 K LAYER SHOULD HELP CLOUDS THICKEN. TONIGHT...BELIEVE THAT THE GFS IS A LITTLE TOO AGGRESSIVE WITH ITS QPF...HOWEVER IT DOES SEEM LIKE THERE IS A GOOD CHANCE FOR PCPN TONIGHT. AFTER COORDINATING WITH DMX, EAX AND TOP...DECIDED TO GO WITH LIKELY POPS TONIGHT FOR PARTS OF SOUTHEAST NEBRASKA AND INTO SOUTHWEST IOWA. EXPECT RAINFALL AMOUNTS MAINLY LESS THAN A QUARTER OF AN INCH...BUT LOCAL AMOUNTS OVER HALF AN INCH WILL BE POSSIBLE. GOOD CHANCE OF RAIN AND THUNDERSTORMS WILL CONTINUE THROUGH SUNDAY NIGHT...THEN KEPT TREND OF TAPERING POPS OFF MONDAY AND MONDAY NIGHT. AT SOME POINT...IT APPEARS THAT A DRY SLOT WILL BE OVER THE AREA. THIS WILL PROBABLY BE SUNDAY AFTERNOON AND EARLY EVENING. KEPT A CHANCE OR SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS FROM WEDNESDAY NIGHT INTO THURSDAY NIGHT. && .AVIATION... FOR TAF SITES KOFK...KOMA AND KLNK. RIDGE AXIS SHIFTING EWD TDY WL ALLOW FOR A CONTD INCREASE IN LO TO MID LVL MOISTURE. THIS IS LIKELY TO LEAD TO SCT-BKN VFR CONDS AT ALL 3 TAF SITES THRU THE DAY ON FRI. WAA INCREASE THIS EVNG IN RESPONSE TO AN INCREASING LO LVL JET ACRS KS/NEB. LIFT SEEMS STG ENOUGH TO GENERATE SCT CONVECTION TOWARD THE END OF THE TAF PERIOD OVR MAINLY THE OMA/LNK TERMINALS. WL INDC CEILINGS DROPPING TOWARD THE END OF THE PERIOD...BUT KEEP THINGS VFR. WL ALSO INCLUDE A CHC OF A -SHRA. LATER SHIFTS CAN FURTHER ADDRESS POTENTIAL CONVECTION AT THESE TAF SITES. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ DISCUSSION...MILLER AVIATION...BOUSTEAD ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1029 AM EDT SAT OCT 13 2007 .SYNOPSIS...SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE REGION FROM THE NORTHWEST THROUGH EARLY NEXT WEEK. AN UPPER LEVEL RIDGE WILL ALSO SLOWLY BUILD OVER THE AREA...ALLOWING A SLOW WARM UP IN TEMPERATURES THROUGH MID WEEK. && .NEAR TERM /THROUGH TONIGHT/... SFC ANALYSIS THIS MORNING SHOWS 1019 MB HIGH PRESSURE CENTERED OVER OH/KY/WV. A VERY WEAK PRESSURE GRADIENT WAS OBSERVED ACROSS THE STATE. AS OF 13Z DEWPOINTS ACROSS CENTRAL NC RANGED FROM THE UPPER 30S TO THE LOWER 40S. 12Z RAOB ANALYSIS SHOWED UNIDIRECTIONAL FLOW ALOFT ACROSS NC/VA. AN UPPER RIDGE WAS BUILDING OVER THE MIDWEST. A DEEP TROUGH WAS LOCATED OVER THE WESTERN US. WEAK TROUGHING WAS OBSERVED OVER GA/FL AND OFF THE WEST FL COAST. A FEW SUBTLE SHORTWAVES WERE NOTED AT H25...ONE BETWEEN ILN-RNK AND ANOTHER BETWEEN LZK AND JAN/BMX. IR SAT IMAGERY SHOWS AN MCS HAS DEVELOPED UPSTREAM THIS MORNING OVER KS/MO...ALONG A STRONG SFC/H85 WARM FRONT UNDER DIFFLUENT FLOW ALOFT AND AHEAD OF 50-90M H5 HEIGHT FALLS ASSOC/W THE DEEP UPPER TROUGH DIGGING INTO THE ROCKIES. FORECAST APPEARS ON TRACK THIS AFTERNOON WITH CLEAR SKIES AND HIGH TEMPS GENERALLY IN THE LOWER 70S. THE 12Z GSO SOUNDING HAD A PWAT OF 0.62" THIS MORNING...VERSUS 0.41" YESTERDAY...SO THE COLUMN HAS MOISTENED SOME. HOWEVER...AFTERNOON DEWPOINTS ARE EXPECTED TO REMAIN IN THE MID/UPPER 30S TO LOWER 40S AND THIS IN ADDITION TO A STRONG MID-LEVEL SUBSIDENCE INVERSION NOTED ON THE 12Z GSO SOUNDING AND IN FCST SOUNDINGS THIS AFTERNOON WILL PREVENT EVEN DIURNAL CU FROM FORMING...AND CLEAR SKIES ARE EXPECTED THIS AFTERNOON. THE ONLY POTENTIAL PROBLEM WITH A CLEAR SKY FORECAST LATER THIS EVENING/TONIGHT IS IF MID/UPPER LEVEL CONVECTIVE DEBRIS CLOUDINESS ASSOC/W THE MCS THIS MORNING OVER MO/KS ADVECTS INTO NC/VA. H7 AND H5 STREAMLINES BASED ON 12Z RAOB DATA AND RUC FCST WIND FIELDS WOULD BE FAVORABLE FOR ADVECTING MID/UPPER LEVEL CLOUD COVER INTO THE AREA...ALTHOUGH WITH 30-40 KT MAX FLOW IN THAT LAYER...IT WOULD PROBABLY NOT HAPPEN UNTIL AFTER SUNSET...AND THAT`S IF IT DOES NOT SUBLIMATE ON THE WAY IN (15-30C DEWPOINT DEPRESSIONS BETWEEN H7-H5 AT GSO/RNK). AT THIS TIME WILL INDICATE MOSTLY CLEAR SKIES TONIGHT. NORMAL TEMPS THIS TIME OF YEAR ARE BETWEEN 70-72F WITH A 1000-850MB THICKNESS AROUND 1368M. THICKNESSES THIS AFTERNOON ARE PROGGED TO BE BETWEEN 1368-1376M... JUST A FEW METERS HIGHER THAN YESTERDAY...AND VERY CLOSE TO SEASONAL NORMS. THE MAX TEMP FORECAST THIS AFTERNOON WILL THEREFORE BE NEAR NORMAL AND VERY SIMILAR TO YESTERDAY...EXCEPT PERHAPS A DEGREE OR TWO HIGHER...AND WILL INDICATE HIGHS BETWEEN 71-75F. -VINCENT && .SHORT TERM /SUNDAY THROUGH MONDAY/... PRIMARILY A TEMPERATURE FORECAST THROUGHOUT THE SHORT TERM PERIOD. LOW OVER NEW ENGLAND WILL LIFT NORTHEAST INTO NOVA SCOTIA BY SUNDAY EVENING...AND AN UPPER LEVEL RIDGE WILL BUILD OVER THE GULF COAST AND SOUTHEAST STATES THROUGH THE WEEKEND. AT THE SURFACE...AN AREA OF HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE AREA FROM THE FROM THE OHIO VALLEY. DRY CONDITIONS SHOULD PERSIST THROUGH THE SHORT TERM. HEIGHTS WILL BE RISING THROUGH THE PERIOD...THUS WE CAN EXPECT A GRADUAL INCREASE IN TEMPERATURES EACH DAY. LOWS TONIGHT WILL BE IN THE LOW TO MID 40S AND IN THE MID 40S TO AROUND 50 SUNDAY NIGHT. HIGHS SUNDAY WILL BE IN THE MID 70S SUNDAY...WARMING TO THE UPPER 70S TO LOWER 80S MONDAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... MODELS CONTINUE DRY TREND THROUGH TUESDAY NIGHT... HOWEVER AS HIGH PRESSURE MOVES OFFSHORE AND A SURFACE BOUNDARY APPROACHES FROM THE WEST... MOISTURE INCREASES OVER THE AREA. THIS MOISTURE COMBINED WITH UPPER LEVEL DISTURBANCES COULD LEAD TO A LOW CHANCE OF RAIN. WHILE THE RAIN WILL DO LITTLE TO RELIEVE THE DROUGHT...ITS POSSIBILITY REMAINS. WILL ADD LOW CHANCE FOR WEDNESDAY SINCE THIS IS WHEN THE STRONGER IMPULSES MOVE THROUGH. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS THROUGH SUNDAY. HIGH PRESSURE CENTERED OVER THE STATE WILL PERMIT FEW TO NO CUMULUS CLOUDS THIS AFTERNOON. WINDS LESS THAN EIGHT KNOTS. HIGH PRESSURE WILL CONTINUE ITS HOLD ON NORTH CAROLINA WEATHER THIS WEEKEND AND INTO THE COMING WORK WEEK. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...RHJ LONG TERM...RHJ AVIATION...RLH nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PENDLETON OR 1137 AM PDT SAT OCT 13 2007 UPDATED AVIATION DISCUSSION .UPDATE...INCREASED CLOUD COVER ACROSS CENTRAL OREGON AS SATELLITE/ASOS SHOWS OVC LAYER FROM 8K-12K MSL. ALTHOUGH CLOUDS SLOW DIMINISH...RUC SHOWS GOOD CLEARING THIS AFTERNOON...SO KEPT CLOUDS TIL 18Z. ALSO WEBCAMS/ASOS SHOWING RADIATION FOG FROM CLE ELUM TO ELLENSBURG...IN DENSE PATCHES. ALTHOUGH WINDS ARE LIGHT...PLENTIFUL SUNSHINE ABOVE AND ON THE EDGES SHOULD DISSIPATE THIS FOG BY NOON AS IT IS SHALLOW AND NOT WIDESPREAD. NO OTHER CHANGES. && .AVIATION...VFR CONDITIONS WITH LIGHT WINDS WILL CONTINUE FOR THE NEXT 24 HOURS. INCREASING HIGH CLOUDS AFTER 12Z. 76 && .PREV DISCUSSION... /ISSUED 235 AM PDT SAT OCT 13 2007/ SHORT TERM...TODAY THROUGH SUNDAY NIGHT. IT WILL BE FAIRLY QUIET WEATHER IN THE SHORT TERM PERIOD WITH DRY CONDITIONS AND RELATIVELY LIGHT WINDS...AT LEAST THROUGH SUNDAY. SURFACE WINDS WILL INCREASE SOME SUNDAY NIGHT AS GRADIENTS TIGHTEN AHEAD OF AN UPPER LEVEL TROUGH MOVING TOWARDS THE COAST...ALTHOUGH THE ONLY AREAS THAT MAY BE BREEZY WILL BE IN THE GRANDE RONDE VALLEY AND LOCALLY IN THE EASTERN COLUMBIA RIVER GORGE. HIGH PRESSURE AT THE SURFACE AND ALOFT WILL STRENGTHEN OVER THE PACIFIC NW THIS WEEKEND...RESULTING IN UNSEASONABLY WARM TEMPERATURES. NO RECORDS ARE ANTICIPATED BUT AFTERNOON TEMPERATURES WILL BE AROUND 3-7 DEGREES ABOVE NORMAL. THE RIDGE WILL SHIFT EASTWARD SUNDAY NIGHT AS THE UPPER LEVEL TROUGH MOVES ONSHORE. CLOUDS WILL INCREASE SUNDAY NIGHT...BUT NO PRECIPITATION IS EXPECTED UNTIL MONDAY. JOHNSON LONG TERM...MONDAY THROUGH FRIDAY...BROAD NORTHEASTERN PACIFIC TROUGH WILL KEEP THE REGION UNDER WESTERLY FLOW ALOFT THROUGH AT LEAST NEXT WEEKEND. ARRIVAL OF FIRST SYSTEM ON MONDAY IS 6 TO 12 HOURS SLOWER THAN INDICATED BY MODELS THIS TIME YESTERDAY. SHADOWING DOES SEEM TO BE A FACTOR WITH THIS ONE AS LOW CONDITIONAL INSTABILITY IS EXPECTED. SYSTEMS WILL CROSS NEARLY EVERY 24 HOURS AFTER THAT WITH EARLY INDICATIONS THAT BULK OF PRECIPITATION WILL OCCUR DURING DAYLIGHT HOURS. BEST WIDESPREAD QPF LOOKS TO OCCUR ON FRIDAY. TEMPERATURES WILL REMAIN SOMEWHAT NEAR NORMAL BUT DO EXPECT RAINFALL AMOUNTS TO BE WELL ABOVE NORMAL IN SOME LOCATIONS BY THE END OF THE WEEK. JBONK && .PRELIMINARY POINT TEMPS/POPS... PDT 65 43 69 44 / 0 0 0 0 ALW 67 45 70 45 / 0 0 0 0 PSC 69 40 70 41 / 0 0 0 0 YKM 67 39 69 39 / 0 0 0 0 HRI 68 39 70 41 / 0 0 0 0 ELN 66 39 68 39 / 0 0 0 0 RDM 65 32 69 36 / 0 0 0 0 LGD 64 37 68 39 / 0 0 0 0 GCD 65 36 70 35 / 0 0 0 0 DLS 70 44 69 46 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...NONE. WA...NONE. && $$ TI:GGG FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT... WWW.WEATHER.GOV/PENDLETON 79/99/76 or AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PENDLETON OR 842 AM PDT SAT OCT 13 2007 .UPDATE...INCREASED CLOUD COVER ACROSS CENTRAL OREGON AS SATELLITE/ASOS SHOWS OVC LAYER FROM 8K-12K MSL. ALTHOUGH CLOUDS SLOW DIMINISH...RUC SHOWS GOOD CLEARING THIS AFTERNOON...SO KEPT CLOUDS TIL 18Z. ALSO WEBCAMS/ASOS SHOWING RADIATION FOG FROM CLE ELUM TO ELLENSBURG...IN DENSE PATCHES. ALTHOUGH WINDS ARE LIGHT...PLENTIFUL SUNSHINE ABOVE AND ON THE EDGES SHOULD DISSIPATE THIS FOG BY NOON AS IT IS SHALLOW AND NOT WIDESPREAD. NO OTHER CHANGES. && .PREV DISCUSSION... /ISSUED 235 AM PDT SAT OCT 13 2007/ SHORT TERM...TODAY THROUGH SUNDAY NIGHT. IT WILL BE FAIRLY QUIET WEATHER IN THE SHORT TERM PERIOD WITH DRY CONDITIONS AND RELATIVELY LIGHT WINDS...AT LEAST THROUGH SUNDAY. SURFACE WINDS WILL INCREASE SOME SUNDAY NIGHT AS GRADIENTS TIGHTEN AHEAD OF AN UPPER LEVEL TROUGH MOVING TOWARDS THE COAST...ALTHOUGH THE ONLY AREAS THAT MAY BE BREEZY WILL BE IN THE GRANDE RONDE VALLEY AND LOCALLY IN THE EASTERN COLUMBIA RIVER GORGE. HIGH PRESSURE AT THE SURFACE AND ALOFT WILL STRENGTHEN OVER THE PACIFIC NW THIS WEEKEND...RESULTING IN UNSEASONABLY WARM TEMPERATURES. NO RECORDS ARE ANTICIPATED BUT AFTERNOON TEMPERATURES WILL BE AROUND 3-7 DEGREES ABOVE NORMAL. THE RIDGE WILL SHIFT EASTWARD SUNDAY NIGHT AS THE UPPER LEVEL TROUGH MOVES ONSHORE. CLOUDS WILL INCREASE SUNDAY NIGHT...BUT NO PRECIPITATION IS EXPECTED UNTIL MONDAY. JOHNSON LONG TERM...MONDAY THROUGH FRIDAY...BROAD NORTHEASTERN PACIFIC TROUGH WILL KEEP THE REGION UNDER WESTERLY FLOW ALOFT THROUGH AT LEAST NEXT WEEKEND. ARRIVAL OF FIRST SYSTEM ON MONDAY IS 6 TO 12 HOURS SLOWER THAN INDICATED BY MODELS THIS TIME YESTERDAY. SHADOWING DOES SEEM TO BE A FACTOR WITH THIS ONE AS LOW CONDITIONAL INSTABILITY IS EXPECTED. SYSTEMS WILL CROSS NEARLY EVERY 24 HOURS AFTER THAT WITH EARLY INDICATIONS THAT BULK OF PRECIPITATION WILL OCCUR DURING DAYLIGHT HOURS. BEST WIDESPREAD QPF LOOKS TO OCCUR ON FRIDAY. TEMPERATURES WILL REMAIN SOMEWHAT NEAR NORMAL BUT DO EXPECT RAINFALL AMOUNTS TO BE WELL ABOVE NORMAL IN SOME LOCATIONS BY THE END OF THE WEEK. JBONK AVIATION...MID LEVEL DECK WILL CONTINUE TO CLEAR OUT THROUGH THE MORNING HOURS. WITH DROPPING WINDS, TEMPERATURES ARE GETTING CLOSE TO THE DEWPOINT AT A FEW OF THE TERMINALS. WITH DRAINAGE WESTERLY WINDS AT KYKM, MAY SEE SOME 3 TO 6 MILE VBSYS BUT DONT THINK WILL DROP INTO MVFR OR LOWER. HAVE CONCERNS DUE TO MISSING VISIBILITY OBSERVATIONS AT KRDM GIVEN FOG FORMATION THIS TIME YESTERDAY. WILL TRY TO MONITOR VIA WEBCAMS BUT MAY HAVE TO NIL VISIBILITY PORTION OF THE TAF SHOULD CONFIDENCE CONTINUE TO DECREASE. OTHERWISE...ANY REDUCED VSBYS SHOULD END SHORTLY AFTER SUNRISE WITH VFR CONDITIONS REMAINING THROUGH 14/12Z. JBONK && .PRELIMINARY POINT TEMPS/POPS... PDT 65 43 69 44 / 0 0 0 0 ALW 67 45 70 45 / 0 0 0 0 PSC 69 40 70 41 / 0 0 0 0 YKM 67 39 69 39 / 0 0 0 0 HRI 68 39 70 41 / 0 0 0 0 ELN 66 39 68 39 / 0 0 0 0 RDM 65 32 69 36 / 0 0 0 0 LGD 64 37 68 39 / 0 0 0 0 GCD 65 36 70 35 / 0 0 0 0 DLS 70 44 69 46 / 0 0 0 0 && .PDT WATCHES/WARNINGS/ADVISORIES... OR...NONE. WA...NONE. && $$ TI:GGG FOR ADDITIONAL WEATHER INFORMATION, CHECK OUR WEB SITE AT... WWW.WEATHER.GOV/PENDLETON 79/99/76 or AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 815 AM EDT FRI OCT 12 2007 .SYNOPSIS... A LARGE...SLOW MOVING LOW PRESSURE SYSTEM OVER SOUTHERN QUEBEC WILL PRODUCE COOL WEATHER ACROSS PENNSYLVANIA TODAY AND SATURDAY. HIGH PRESSURE WILL BUILD INTO THE REGION FROM THE WEST SUNDAY AND MONDAY. A STORM SYSTEM WILL APPROACH FROM THE MIDWEST BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... DEFORMATION RAIN SHIELD GONE NOW...AS MID LVL LOW CENTER CONTINUES TO LIFT INTO NEW ENGLAND. HOWEVER...CUT OFF UPPER LO OVR SOUTHERN QUEBEC WILL KEEP CENTRAL PA IN A CHILLY/UNSETTLED WX PATTERN TDY. LAKE/850 TEMP DIFFS ARND 21C SHOULD PRODUCE NUMEROUS LAKE EFFECT SHWRS DOWNWIND OF LK ERIE. NNW FETCH OVR LAKES WILL FAVOR THE HIGHEST POPS ACROSS THE LAUREL HIGHLANDS AND PERHAPS WARREN CO. HAVE GONE WITH POPS ABV MOS GUIDANCE IN THESE AREAS. WILL COMNTINUE TO MENTION SPRINKLES IN A STRIPE THROUGH IPT/UNV/AOO. EAST OF MTNS...DOWNSLOPING FLOW SHOULD PRODUCE BRKS IN THE OVERCAST WITH MSUNNY SKIES DEVELOPING ACROSS THE LOWER SUSQ VALLEY. TIGHT PRES GRADIENT ASSOCIATED WITH COASTAL LOW WILL RESULT IN GUSTY WINDS TDY...ESPECIALLY ACROSS EASTERN PA. CURRENT FCST HAS GUSTS BTWN 20-25KTS. HOWEVER...LATEST RUC DATA INDICATING 850 WINDS NEAR 40KTS ACROSS SUSQ VALLEY...SO HAVE MENTIONED BREEZY AND GUSTS INTO 25-30 MPH RANGE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... BLYR FLOW BACKING TO THE WEST WILL SHIFT FOCUS OF LAKE EFFECT RAIN SHWRS INTO NW PA TONIGHT AND SATURDAY. SREF DATA AND CLIMATOLOGY STRONGLY SUGGEST THE HIGHEST POPS WILL BE OVR WARREN CO. ELSEWHERE...MCLEAR SKIES EXPECTED SOUTH OF I-80. ENSEMBLE 850 TEMPS MODERATE SLIGHTLY TO ARND 2C ON SATURDAY...SUGGESTING HIGH TEMPS FROM L50S NW MTNS TO M60S LOWER SUSQ VALLEY. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... 00Z GEFS DATA SHOWS UPPER LOW LIFTING OUT BY SUNDAY. FAIR AND MILDER CONDITIONS APPEAR LIKELY SUNDAY AND MONDAY AS SFC HIGH BUILDS OVR THE REGION. MED RANGE MODEL GUIDANCE SUGGESTS A DISTURBANCE...CURRENTLY COMING ASHORE OVR NORTHERN CALIFORNIA...WILL CUT OFF FROM THE MAIN JET STREAM AND SLOWLY TRACK EASTWARD ACROSS THE PLAINS TOWARD PA BY MIDWEEK. A PERIOD OF SHOWERY WX WILL LIKELY ACCOMPANY THIS SYSTEM AS EARLY AS TUESDAY...AND POSSIBLY LINGERING UNTIL THURSDAY. LATEST GEFS DATA SUPPORTS A RETURN TO DRY WX BY FRIDAY AS THIS SYSTEM MOVES EAST OF PA. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... CYCLONIC FLOW AROUND DEPARTING LOW PRESSURE WILL CONTINUE TODAY WITH A GOOD DEAL OF STRATOCU COVERING THE REGION. CLEAR SLOT THRU FKL/DUJ/AOO SHOULD FILL BACK IN LATER TODAY WITH BACKING- UPSLOPE FLOW. PERIODS OF MVFR CIGS AND BRIEF VSBYS IN SHOWERS ARE EXPECTED AT KJST AND KBFD. ELSEWHERE...STRATOCU CIGS AROUND LOWER END VFR RANGE SHOULD PREVAIL. A GUSTY...DOWNSLOPE FLOW INTO THE SERN TERMINALS SHOULD EAT AWAY AT THE LOW CLOUDS...SO CIGS MAY GO SCT BY THE AFTN HOURS. WNWLY SFC WNDS WILL INCREASE TO AROUND 15 KTS AFTER 14Z WITH OCNL GUSTS AROUND 25KTS. WIDESPREAD CLEARING CONDITIONS MAY NOT ARRIVE UNTL SUNDAY/MONDAY...ESP ACROSS THE NW MTS AS THE BROAD CYCLONIC FLOW FINALLY LOOSENS ITS GRIP ON THE REGION. SFC HI PRES BUILDS IN FOR EARLY NEXT WEEK WITH VFR CONDITIONS DOMINATING THE PERIOD. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD NEAR TERM...DANGELO/FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD/TYBURSKI AVIATION...DANGELO/LAMBERT/GARTNER pa AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 920 PM CDT SAT OCT 13 2007 .DISCUSSION... INIT BAND OF PCPN BEHAVING AS FORSEEN FOR WRN AND NRN PARTS OF FCST AREA. HWVR DVLPMNT IN NWRN IA HAD BEEN RATHER WIMPY. FRTHRMORE MODELS INCLUDG LATEST RUC AND NEW NAM12 KEEP MOST SUPPORT FOR PCPN OUT OF THE SERN CRNR THRU MOST OF TNGT. WITH GREATER INSTBLTY SPRDG SLWLY NWD TWRDS THIS AREA WILL CUT TO SCT/CHC FROM WDSPRD/LIKELY FOR MOST OF TNGT BUT BRING BACK UP TO LIKELY LATE. THIS WILL BE THE MAIN CHANGE IN FCST. OF COURSE IF NEW DVLPMNT ON SRN END OF BAND CONTS TO BE AS LIGHT AS IT HAS BEEN SO FAR...WE CUD BE LEFT WITH LTL OR NOTHNG UP THIS FAR AT FSD AFTER MIDNGT. QPF ADJUSTD ACCORDNGLY...MAYBE NOT DOWN ENUF IN THE SE BUT IF THERE IS NEW CONVECTN MOVG INTO THAT AREA LATE TNGT IT CUD PACK A DECENT RAINFALL PUNCH. && .AVIATION... PLENTY OF AVN CONCERNS TONIGHT THROUGH SUNDAY. WIDESPREAD IFR/LIFR CIGS PERSIST AROUND KSUX...AND ANY NORTHWARD PUSH TO THIS VERY LOW LEVEL MOISTURE IS MEETING RESISTANCE FROM DRIER ELY-NELY LOW LEVEL FLOW NEAR AND NORTH OF I-90. NORTHWARD SURGE OF LOW LEVEL MOISTURE SHOULD BE ASSISTED BY LEADING BAND OF SHRA/EMBEDDED TSRA NEAR I-90 AS OF 02Z...AS RAIN AIDS IN SATURATING LOWEST LEVELS FARTHER NORTH. IFR-LIFR CIGS/MVFR-IFR VSBYS EXPECTED INTO KFSD AFTER 05Z. LOWEST CIGS/VSBYS WILL HAVE A TOUGHER TIME MAKING IT TO KHON...ALTHOUGH A PERIOD OF MVFR-IFR CIGS AND VSBYS POSSIBLE LATER TONIGHT...08Z-14Z TIME FRAME. LOW LEVEL RH FORECAST SHOWS LOW END MVFR-IFR CIG POTENTIAL PERSISTING THROUGH MUCH OF SUNDAY AT KFSD/KSUX...WHILE KHON CONTINUES TO FLIRT WITH DRIER NELY FLOW AND PERIODS OF HIGHER END MVFR-VFR CONDITIONS AFTER 14Z. && .PREV DISCUSSION... WV IMAGERY SHOWS THE CENTER OF THE UPPER LOW SPINNING JUST NW OF THE FOUR CORNERS AREA...PROGGED TO MOV EWD INTO ERN CO BY 12Z SUNDAY. THERE LOOKS TO BE SOME S/W ENERGY ON THE FRONT SIDE OF THE LOW CENTER ATTM IN ERN CO/EXTREME WRN KS MOVG RAPIDLY NEWD. THIS WAVE DOES LOOK TO BE DEPICTED BY THE NAM...BUT WASHED OUT SOME BY THE GFS. THAT BEING SAID...ISENTROPIC LIFT AND WAA IS IN NO SHORT SUPPLY THIS EVENING AND OVERNIGHT. THEREFORE THE LOW LEVEL MSTR SHOULD BEGIN TO SATURATE INTO AREAS ALONG I 90 VERY EARLY TNGT...SPREADING INTO KHON TO KMML BY THE MIDDLE OF THE NIGHT. SOME OVERALL DRYING IS DEPICTED BY THE NAM CLOSE TO KSUX AND STORM LAKE LATE TONIGHT... WHICH COULD INHIBIT A BIT OF PCPN DEVELOPMENT IN THOSE AREAS...THUS DROPPED THE POPS DOWN TO LIKELY WITH LOW LEVEL MSTR REMAINING VERY HIGH. CANNOT RULE OUT DRIZZLE LATE TONIGHT FM KSUX TO STORM LAKE BUT SINCE IT IS OF THE LIQUID VARIETY...JUST OPTED TO STAY SHOWERS. CONVERSELY...POPS WL GREATLY INCREASE ACROSS OUR NORTH AS THE NIGHT PROGRESSES USING THE LIMITING STREAMLINE FM THE NAM/GFS AT H85-H7 AS A GUIDE WHICH IS WELL NORTH OF OUR FA. DID NOT ALTER OUR GOING LOWS MUCH AT ALL...RELYING HEAVILY ON THE NAM H925 TEMPS VALID FOR 12Z SUNDAY AS A GUIDE. THE GFS H925 TEMPS LOOK TOO COLD. REST OF SHORT TERM CERTAINLY LOOKS WET FOR A GOOD DEAL OF THE AREA... AND WITH ABUNDANCE OF LOW CLOUDS...TMPS WL NOT BE MAKING ANY AGGRESSIVE CHANGES UP OR DOWN AFTER INITIAL SATURATIONAL COOLING. PERSISTENT ISENTROPIC LIFT SETS UP AS UPR SYSTEM MAKES SLOWING APPROACH TO AREA THRU SUN NIGHT AND MONDAY. WL HAVE TO WATCH AND SEE HOW SIGNIFICANT DEVELOPING PCPN AREA IS INVERTED TROUGH AS IT TAKES SHAPE POKING NWRD THRU ERN SD WITH APPROACH UP MAIN UPR SYSTEM SUNDAY...COLLAPSING SLOWLY SWWRD THRU EARLY TUE AS WASHES OUT. GFS IS REALLY FOCUSING WAA ALG/W OF THIS FEATURE...WITH STRONG FRONTAL FORCING ALIGNING WITH PV ADVECTION LATE AFTN AND INTO SUNDAY NIGHT. THIS WOULD RESULT IN AN AREAS OF SECONDARY HVY PCPN OUT TOWARD/W OF LOWER JAMES VALLEY. TIMING OF PCPN IS DIFFICULT WITH THE LARGE DEGREE OF CONVECTION IN THE MDL SLNS AFFECTING BASE FIELDS. THUNDER THREAT LOOKS TO BE MOST LIKELY IN AREAS S OF A MML TO PKS LINE AT TIMES THROUGH SUNDAY NIGHT...WITH MONDAY THREAT SOMEWHAT TO S OF THIS DURING AFTN/EVNG HOURS. LIMITING STREAMLINE FOR PCPN REMAINS JUST N AND W OF CWA...SO CONVECTIVE CELLS SHUD CONTINUE TO DEVELOP AND FEED INTO MAIN DEFORMATION BAND. DRY SLOT LOOKS TO MOVE N INTO AREA SUN NIGHT AND MONDAY WITH MAIN UPR LOW LIFTING INTO NEBRASKA...AND THIS CUD SHUD DOWN PCPN TOWARD MORE OF A DZ/SCT SHRA EPISODE OVR ERN CWA FOR A TIME LTR SUN NIGHT/MON...WHILE MORE DISCERNABLE PCPN BAND SHIFTS TO THE N AND W...AND CONVECTION WHICH DEVELOPS SUN AFTN/EVNG CLOSER TO THE LOW LVL INSTABILITY AXIS IN WRN IA/ERN NEBRASKA SHIFTS OFF TOWARD THE E. LKLY TO FIND A RESURGENCE IN PCPN AGAIN MON AFTN/EVENING CLOSER TO CORE OF UPR CIRC MOVING TOWARD LOWER MO VLY...WHICH RESULTS IN LINGERING PCPN A BIT LONGER INTO MONDAY NIGHT AND TUE...ESPLY ERN CWA. DISARRAY CONTINUES IN THE EXTENDED RANGE DEALING WITH SPLIT FLOW PATTERN. SLNS BETWEEN MDLS/RUNS ARE SO VARIED IT IS HARD TO GET A PICTURE ON THE UPCOMING EVOLUTION NOT ONLY WITH GRADUAL DEMISE OF SHORT TERM SYSTEM...BUT WITH NEXT TROUGH COMING ONTO W COAST AND PUSHING INTO THE PLAINS LATE NEXT WEEK. PROBLEM WITH USING A PURE ENSEMBLE APPROACH IS THAT THERE IS A STRONG BIAS TOWARDS LOWER AMPLITUDE...HOWEVER...STILL MAY GET SOME USEFUL INFORMATION FROM CLUSTERING...WHICH SUGGESTS THAT APPROACHING TROUGH SHUD BE SOMEWHAT SLOWER AND MORE SPLITTY CLUSTERING THAN BULLISH PROGRESSION OF 00Z ECMWF AND 12Z GFS. NOT SURE MUCH FAITH CAN BE PLACED IN SLNS WHICH TAKE UPR LOW AND REATTACH THE PV TO THE WRN TROUGH RESERVOIR WED AND WED NIGHT...NOR ANY RUN THAT AGGRESSIVELY PUSHES WAVE INTO RIDGE BETWEEN SYSTEMS. SIDED MORE WITH A SPLITTING SCENARIO...WITH MORE ENERGY DIGGING TOWARD SRN PLAINS AND MORE TOWARD CANADA PER CANADIAN/UK...BUT NOT SO EXTREME NRN STREAM AS UK. HOWEVER...WL SAY THAT SUCH EXTREME DEVELOPMENTS ARE NOT UNCHARACTERISTIC OF THIS PATTERN. FOR NOW...CONTINUED WITH IDEA THAT CLOUDS WL HANG TOUGH...ESPLY NRN/ERN CWA...INTO WED...WHICH MAY BE ECLIPSED BY NEW MID/HIGH CLOUDS AHEAD OF NEXT SYSTEM. KEPT SMALLER DIURNAL RANGES...BUT WITH STRENGTHENING S FLOW...MAY BE ABLE TO FLUSH CLOUDS OUT EARLY ENOUGH S/W IN CWA TO ALLOW FOR SOME BETTER WARMING WED. NOT MUCH CHANGE MADE TO SYSTEM MOVING IN WED NIGHT...AND LINGERING INTO FRIDAY IN E. MORE TEMPORAL COVERAGE HERE IS DUE TO UNCERTAINTY IN TIMING RATHER THAN A LONG TERM PRECIP THREAT. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. && $$ WILLIAMS/JH sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 814 PM CDT SAT OCT 13 2007 .UPDATE... MADE SOME MINOR ADJUSTMENTS TO POP FORECAST TONIGHT BASED ON RADAR TRENDS AND SHORT TERM MODEL FORECASTS. WV IMAGERY THIS EVENING SHOWS A POSITIVE TILT UPPER TROUGH CHURNING THROUGH THE 4-CORNERS REGION...WITH STRONG /100+ KNOT/ UPPER LVL JET STREAK PUNCHING NEWD INTO THE CENTRAL PLAINS. RUC INDICATING STRONG H4-H2 UPPER DIVERGENCE OVER MAJORITY OF SOUTH DAKOTA AS REGION LIES IN FAVORABLE POSITION IN THE LEFT EXIT REGION OF UPPER JET. RADAR MOSAIC SHOWS BROAD AREA OF MAINLY LIGHT SHOWERS ONGOING OVER PORTIONS OF WRN AND CENTRAL SD...WITH MOST LOCATIONS ACROSS THE CWA PICKING UP ONLY A FEW HUNDRETHS. A MORE IMPRESSIVE AREA OF RAINFALL CURRENTLY ROTATING NWD OUT OF NEBRASKA...WITH EVEN SOME EMBEDDED CONVECTION. THIS RAINFALL ASSOCIATED WITH BAND OF STRONG MID LEVEL FRONTOGENESIS. RUC/NAM/GFS AGREE ON LIFTING STRONG FRONTOGENESIS NWD TOWARDS CENTRAL SD BY 06Z...WITH WEAKENING TREND NOTED BY 12Z SUN. RAISED POPS TO NEAR 100% BASICALLY ALONG AND SOUTH OF A LINE FROM WATERTOWN TO REDFIELD TO PIERRE TONIGHT AS STRONGEST LIFT MOVES THROUGH. CONTINUED TREND OF VERY TIGHT POP GRADIENT FROM SOUTH TO NORTH THRU AREA AS MOISTURE FROM SOUTH WILL CONTINUE TO BATTLE WITH DRY AIR ENTRAINMENT FROM THE NORTH. && .PREV DISCUSSION... .SHORT TERM...SATURDAY THROUGH TUESDAY MORNING 100KT JET MAX ROUNDING BASE OF UPPER TROF OVER SOUTHERN ROCKIES NORTHEAST INTO CENTRAL PLAINS...STRONGLY DIVERGENT FLOW EXTENDS INTO WESTERN SD HELPING TO PRODUCE LIGHT SHOWERS ACROSS THE WESTERN AND SOUTHER CWA...WHILE TO THE EAST...UPPER RIDGE KEEPING NORTHEAST CWA DRY DESPITE INCREASING MID AND UPPER CLOUDS. DEVELOPING LOW PRESSURE AND TRANSITORY RIDGE ALONG NORTHERN CONUS HELPING TO PRODUCE LIGHT EASTERLY/NORTHEASTERLY FLOW. WITH LIGHT EASTERLY/NORTHEAST FLOW ACROSS THE STATE OVERNIGHT KEEPING LOW TO MID 40F DEWPOINTS...AND WITH INTERMITTENT SHOWERS...QUESTIONS ARISE ABOUT POTENTIAL FOR FOG. CLOUD COVER WILL BE INHIBITING FACTOR THOUGH SO HAVE NOT PLACED IN GRIDS AT TIME. UPPER TROF DEVELOPS INTO UPPER LOW SUNDAY AM...WITH LOW LEVEL/SURFACE LOW AND INVERTED TROF FORMING OVER THE CENTRAL PLAINS. THIS WILL MAINTAIN EASTERLY/NORTHEASTERLY LOW LEVEL FLOW ACROSS THE STATE. SREF PWATS +2 TO +3 STANDARD DEVIATIONS ABOVE ACROSS THE SOUTHERN EXTENT OF ABR CWA/PWATS BETWEEN 0.75 TO 1 INCH...DROPPING RAPIDLY NORTHWARD. BEST ISENTROPIC LIFT SHOULD BE SOUTH OF OUR CWA AS WELL. WITH DRIER AIR ALONG OUR NORTHERN COUNTIES...SHARP CUT OFF IN PRECIPITATION/CLOUD COVERAGE CONTINUES TO BE A FORECAST ISSUE ALONG THE NORTHER TIER OF SD. MODEL CONSISTENCY BECOMES AN ISSUE EARLY MONDAY AS SOLUTIONS BEGIN TO DIVERGE IN HOW TO HANDLE UPPER LOW. THIS WAS EVIDENT EVEN IN LAST NIGHTS ENSEMBLES. CHOSE NOT TO BITE ON ANY ONE SOLUTION AND ALIGNED MORE WITH PREVIOUS FORECAST FOR CONSISTENCY IN THE HOPES THAT BETTER CONSISTENCY COMES IN 00Z RUNS. .LONG TERM...TUESDAY THROUGH SATURDAY STILL A LOT OF UNCERTAINTY IN THE MID RANGE FORECAST TODAY. MODELS STILL NOT SURE HOW TO HANDLE UPPER LOW FROM THE SHORT TERM PERIOD. THEY ARE IN PRETTY GOOD AGREEMENT THAT THE UPPER LOW WILL CUT OFF AND SIT SOMEWHERE IN THE VICINITY...BUT EXACTLY WHERE IS THE QUESTION. THE OTHER BIG DIFFERENCES HAVE TO DO WITH WHAT HAPPENS TO THIS UPPER LOW. WITH A HIGH OVER LOW TYPE PATTERN...MODELS ARE STRUGGLING AS TO WHAT SORT OF INFLUENCE IT WILL HAVE. PER THE GFS...THE SYSTEM WEAKENS AND LIFTS NORTH AHEAD OF THE NEXT UPPER LEVEL TROUGH BECAUSE OF THE BLOCKING HIGH. THE NAM KEEPS THE HIGH FARTHER NORTH...SO IT KEEPS THE CUT-OFF LOW RATHER STRONG AND SLOWLY MEANDERS IT EAST. THE ECMWF WEAKENS IT AS THE RIDGE STRENGTHENS TO THE NORTH. WITH SO MUCH UNCERTAINTY...DECIDED TO ADD SOME LOW POPS IN FOR EARLY TUESDAY AS ALL MODELS HINT THAT UPPER LEVEL LOW WILL BE SOMEWHERE IN THE VICINITY. COOLER AIR ALOFT WITH THE LOW SHOULD LEAD TO SOME SHOWER ACTIVITY. BEYOND THAT...KEPT THE FORECAST DRY WITH VERY FEW CHANGES THROUGH WEDNESDAY AS WE SHOULD SEE A BREAK FROM THE UPPER LOW AND THE NEXT INCOMING TROUGH. SOME TIMING DIFFERENCE WITH THIS NEXT TROUGH...BUT KEPT IDEA OF A SLIGHT CHANCE TO CHANCE OF PRECIPITATION WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. WILL SEE A SLIGHT WARM-UP IN THIS PERIOD OF THE FORECAST WITH TEMPERATURES CLOSE TO NORMAL. FOR FRIDAY THROUGH SATURDAY...THE EXTENDED MODELS DISAGREE WITH THE HANDLING OF THIS UPPER LEVEL TROUGH OVER THE CENTRAL CONUS. THE 06Z GFS SHOWS A WEAK UPPER LEVEL RIDGE OVER THE SOUTHEAST...AND THE DEEP TROUGH STRETCHING FROM SOUTHERN CANADA SOUTHWARD INTO THE FOUR CORNERS REGION. AS THIS TROUGH PROGRESSES EASTWARD...GFS ADVERSITIES A CLOSED LOW OVER THE DEEP SOUTH. THE ECMWF FOR THE SAME TIME PERIOD HAS A RATHER WEAK TOUGH OVER THE OHIO RIVER VALLEY. WITH SO MUCH DISCREPANCY...HAVE MADE ONLY MINOR CHANGES TO THE HPC GRIDS. && .AVIATION... RADAR MOSAIC SHOWING SCATTERED LIGHT SHOWERS OVER CENTRAL SD AND EXPECT THIS ACTIVITY TO CONTINUE OVERNIGHT AS ADDITIONAL BANDS OF RAIN ROTATE NWD INTO REGION. EXPECTING MAINLY VFR CONDITIONS THRU 06Z AS CIGS REMAIN AOA 5K FEET AGL WITH GOOD VSBYS DUE TO LIGHT PRECIP INTENSITY. AS LOW PRESSURE SYSTEM EJECTS SLOWLY NWD...EXPECTING A PERIOD OF STEADY RAINFALL AT KPIR/KATY WITH CIGS TO GRADUALLY FALL INTO THE MVFR RANGE BTWN 06-09Z. LOW CONFIDENCE IN NWD EXTENT OF PRECIP...SO WILL KEEP PRECIP OUT OF KABR TERMINAL FOR NOW. ALTHOUGH GUIDANCE NOT SUGGESTING IT...COULD ALSO SEE FOG DEVELOP ACROSS NERN SD LATER TONIGHT AS T/TD SPREADS CLOSE. WILL INCLUDE MVFR VSBYS FOR NOW AT KABR...AND CONTINUE TO MONITOR. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...FOWLE SHORT TERM...CONNELLY LONG TERM...ZELTWANGER AVIATION...FOWLE sd AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 1032 AM CDT SAT OCT 13 2007 .DISCUSSION... JUST FRESHENED UP SOME GRIDS AND UPLOADED THEM...AS WELL AS FINE TUNED A BIT OF WORDING IN THE ZFP TEXT. SO FAR...MID CLOUDS HAVE ERODED QUITE A BIT ALONG AND NE OF A HURON...TO SIOUX FALLS TO JACKSON MN LINE AS THEY TRY TO STREAM NEWD. NEW NAM RH TIME SECTIONS CLEARLY SHOW THE MID LVL CLOUD DECK STILL EEKING NEWD AS THE DAY PROGRESSES...ENCOMPASSING AREAS AROUND MARSHALL MN LAST. WHERE SKIES ARE PARTLY SUNNY...NAM SNDGS SHOW A MIX OUT TO H875 ON AVERAGE IN SW MN...AND IN AREAS FM HURON...TO BROOKINGS TO SIOUX FALLS. SO ATTM...HIGH TEMPS LOOK GOOD IN THOSE AREAS BUT WL MONITOR. WL LIKELY HAVE TO LOWER HIGHS AROUND CHAMBERLAIN TODAY WITH THICK CLOUDS IN THAT AREA. NW IA TO YANKTON ALSO LOOK PRETTY GOOD. PCPN WISE...A BAND OF -SHRA/DZ HAS SETUP IN OUR MO RIVER VALLEY ALONG AN H85 FRONTOGENETIC AXIS...JUST N OF THE SFC INVERTED TROF. SOME OF THIS FRONTOGENESIS WANES THIS AFTERNOON...HOWEVER BY THEN A STRONG H7-H7 -DIV Q BEGINS TO ENCROACH INTO OUR SW QUARTER. SO OUR PCPN FCST LOOKS ON TRACK ATTM WITH SOME VERY MINOR TWEAKS FOR THE MORNING HRS. && .AVIATION... AREA OF MOST CONCERN TODAY IS FOCUSED ON THE SOUTHERN PART OF THE CWA...AS LOW LEVEL MOISTURE EXPANDS NORTHWARD NORTH OF A SFC INVERTED TROF AS EVIDENCED BY THE IFR TO LIFR CIGS/VIS ACROSS MUCH OF NEBRASKA AND PORTIONS OF IOWA. SHOWERS VICINITY OF KSUX THIS MORNING IS LEADING TO MVFR CIGS GETTING LOCKED INTO THAT AREA...PROBABLY LOWERING TO IFR AND RAIN AS THIS AFTERNOON PROGRESSES AND THRU TONIGHT. RELATIVELY DRIER EASTERLY FLOW OF LOW LEVEL DRY AIR WILL KEEP KFSD VFR THRU LATE AFTERNOON AND KHON VFR INTO THE EARLY EVENING. MVFR CIGS AND RAIN INTO KFSD AFTER 14/02Z...FINALLY LOWERING TO MVFR CIGS AND RAIN AT KHON AROUND 14/04Z. && .PREV DISCUSSION... OVERALL PATTERN LOOKING VERY BLOCKY WITH STRONG LOW RETROGRADING OVER THE NORTHEAST U.S. WHILE A STRONG LOW DIGS INTO THE SOUTHWEST U.S. WITH STRONG RIDGING OVER THE CENTRAL U.S....INCOMING ENERGY REALLY HAS NOWHERE TO GO BUT EAST AND NORTH. SO...AS ANTICIPATED EARLIER THIS WEEK...MODELS...ESPECIALLY THE GFS AND ITS` ENSEMBLE PARTNERS...HAD A SOUTH BIAS AND INSTEAD OF GETTING VIRTUALLY NOTHING AS THEY SUGGESTED...MANY LOCATIONS SHOULD END UP GETTING ONE TO THREE INCHES OF RAIN ON THE THIRD WET SUNDAY IN A ROW. IN FACT...RAIN LOOKS PRETTY LIKELY FROM LATE THIS AFTERNOON THROUGH MONDAY MORNING. BEST UPPER LEVEL SUPPORT APPEARS TO MOVE INTO THE AREA TONIGHT...THEN CONTINUES RIGHT ON THROUGH MONDAY. AREAS FROM ABOUT INTERSTATE 29 WEST WILL SEE THE BEST CHANCE FOR HEAVY RAIN FROM TONIGHT THROUGH SUNDAY MORNING. THE FOCUS SHOULD THEN SHIFT INTO NORTHWEST IOWA AND SOUTHWEST MINNESOTA ON SUNDAY AFTERNOON AND EVENING AS A STRONG LOW LEVEL BOUNDARY...DECENT LOW LEVEL INSTABILITY IN THE FORM OF LI`S IN THE 925-800MB LAYER AROUND 0 TO -3 AND PLENTY OF UPPER LEVEL SUPPORT SHOULD ALLOW FOR THUNDERSTORMS WITH HEAVY RAIN TO DEVELOP. SO...FOR TODAY...WILL SEE A SLOW SURGE OF MOISTURE FROM THE SOUTH AS UPPER LEVEL SUPPORT POURS ONTO THE PLAINS. WILL INCREASE POPS A LITTLE OVER THE SOUTHERN MISSOURI RIVER REGION...AND TAPER THEM OFF QUICKLY AROUND INTERSTATE 90. TEMPERATURES SHOULD STRUGGLE TODAY WITH AN ABUNDANCE OF CLOUD COVER AND A LESS FAVORABLE EAST WIND. AS ALWAYS...STRATUS A TRICKY CALL...BUT RUC HAS A DECENT HANDLE ON LOW STUFF OVER NEBRASKA...AND THIS SHOULD SHIFT NORTH AND REMAIN OVER THE SOUTHERN QUARTER OF THE CWA THROUGH MUCH OF THE DAY...LIMITING ANY HEATING IN THATR AREA. OVERALL...LOW TO MID 60S FOR HIGHS...POSSIBLY A LITTLE LOWER IF THE LOW TO MID LEVEL DECK OF CLOUDS SETTLES IN FOR THE ENTIRE DAY. TONIGHT...RAIN AND ISOLATED THUNDERSTORMS WILL SPREAD NORTH...BRINGING MEASURABLE RAINFALL TO MOST LOCATIONS. SHOULD BE A PRETTY GOOD POTENTIAL FOR AROUND AN INCH OF RAIN ALONG I90 TONIGHT AS FORCING SETTLES IN AND IS SLOW TO MOVE. HEAVIEST RAIN SHOULD OCCUR FROM ABOUT 3Z THROUGH 12Z. LEFT GOING LOWS ABOUT THE SAME AS 925MB TEMPS SUPPORT LOWS FROM ABOUT THE MID 40S NORTH TO THE LOWER 50S SOUTH. SUNDAY A LITTLE BIT TRICKY AS MODEL SOLUTIONS DIVERGE A BIT AND WITH UPPER LEVEL LOW STILL OVER EASTERN COLORADO...MAY HAVE A BRIEF BREAK IN THE ACTION BEFORE ANOTHER ROUND OF CONVECTION DEVELOPS AROUND THE INVERTED TROF AND FEEDS NORTHEAST LATE SUNDAY AFTERNOON AND NIGHT. PLENTY OF UPPER LEVEL SUPPORT AS WELL AS INSTABILITY TO SUPPORT RAIN ON EITHER SIDE OF THE INVERTED TROF...SO HIGH POPS EVERYWHERE AGAIN. WITH A DECENT POTENTIAL FOR LOTS OF CLOUDS AND OFF AND ON PRECIP...SOMETHING CLOSE TO ISOTHERMAL FROM 925MB OR A FEW DEGREES WARMER THAN SEEMS IN LINE. THIS WOULD PUT HIGHS IN THE UPPER 40S TO MID 50S OVER THE NORTHERN HALF...WITH SOME LOWER 60S IN NW IA POSSIBLE IF FRONT CAN SLOW UP ENOUGH. SUNDAY NIGHT WILL SEE RAIN OVER MOST LOCATIONS AGAIN...WITH THE BEST CHANCE OVER THE SOUTHEAST HALF OF THE CWA. VERY LITTLE DIURNAL RANGE THROUGH SUNDAY NIGHT INTO MONDAY WITH AN ABUNDANCE OF LOW CLOUDS LIKELY. HIGH POPS CONTINUE RIGHT ON INTO MONDAY. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. && $$ MJF PREV FCST...08 AND HARMON sd AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 327 AM CDT SAT OCT 13 2007 .DISCUSSION... OVERALL PATTERN LOOKING VERY BLOCKY WITH STRONG LOW RETROGRADING OVER THE NORTHEAST U.S. WHILE A STRONG LOW DIGS INTO THE SOUTHWEST U.S. WITH STRONG RIDGING OVER THE CENTRAL U.S....INCOMING ENERGY REALLY HAS NOWHERE TO GO BUT EAST AND NORTH. SO...AS ANTICIPATED EARLIER THIS WEEK...MODELS...ESPECIALLY THE GFS AND ITS` ENSEMBLE PARTNERS...HAD A SOUTH BIAS AND INSTEAD OF GETTING VIRTUALLY NOTHING AS THEY SUGGESTED...MANY LOCATIONS SHOULD END UP GETTING ONE TO THREE INCHES OF RAIN ON THE THIRD WET SUNDAY IN A ROW. IN FACT...RAIN LOOKS PRETTY LIKELY FROM LATE THIS AFTERNOON THROUGH MONDAY MORNING. BEST UPPER LEVEL SUPPORT APPEARS TO MOVE INTO THE AREA TONIGHT...THEN CONTINUES RIGHT ON THROUGH MONDAY. AREAS FROM ABOUT INTERSTATE 29 WEST WILL SEE THE BEST CHANCE FOR HEAVY RAIN FROM TONIGHT THROUGH SUNDAY MORNING. THE FOCUS SHOULD THEN SHIFT INTO NORTHWEST IOWA AND SOUTHWEST MINNESOTA ON SUNDAY AFTERNOON AND EVENING AS A STRONG LOW LEVEL BOUNDARY...DECENT LOW LEVEL INSTABILITY IN THE FORM OF LI`S IN THE 925-800MB LAYER AROUND 0 TO -3 AND PLENTY OF UPPER LEVEL SUPPORT SHOULD ALLOW FOR THUNDERSTORMS WITH HEAVY RAIN TO DEVELOP. SO...FOR TODAY...WILL SEE A SLOW SURGE OF MOISTURE FROM THE SOUTH AS UPPER LEVEL SUPPORT POURS ONTO THE PLAINS. WILL INCREASE POPS A LITTLE OVER THE SOUTHERN MISSOURI RIVER REGION...AND TAPER THEM OFF QUICKLY AROUND INTERSTATE 90. TEMPERATURES SHOULD STRUGGLE TODAY WITH AN ABUNDANCE OF CLOUD COVER AND A LESS FAVORABLE EAST WIND. AS ALWAYS...STRATUS A TRICKY CALL...BUT RUC HAS A DECENT HANDLE ON LOW STUFF OVER NEBRASKA...AND THIS SHOULD SHIFT NORTH AND REMAIN OVER THE SOUTHERN QUARTER OF THE CWA THROUGH MUCH OF THE DAY...LIMITING ANY HEATING IN THATR AREA. OVERALL...LOW TO MID 60S FOR HIGHS...POSSIBLY A LITTLE LOWER IF THE LOW TO MID LEVEL DECK OF CLOUDS SETTLES IN FOR THE ENTIRE DAY. TONIGHT...RAIN AND ISOLATED THUNDERSTORMS WILL SPREAD NORTH...BRINGING MEASURABLE RAINFALL TO MOST LOCATIONS. SHOULD BE A PRETTY GOOD POTENTIAL FOR AROUND AN INCH OF RAIN ALONG I90 TONIGHT AS FORCING SETTLES IN AND IS SLOW TO MOVE. HEAVIEST RAIN SHOULD OCCUR FROM ABOUT 3Z THROUGH 12Z. LEFT GOING LOWS ABOUT THE SAME AS 925MB TEMPS SUPPORT LOWS FROM ABOUT THE MID 40S NORTH TO THE LOWER 50S SOUTH. SUNDAY A LITTLE BIT TRICKY AS MODEL SOLUTIONS DIVERGE A BIT AND WITH UPPER LEVEL LOW STILL OVER EASTERN COLORADO...MAY HAVE A BRIEF BREAK IN THE ACTION BEFORE ANOTHER ROUND OF CONVECTION DEVELOPS AROUND THE INVERTED TROF AND FEEDS NORTHEAST LATE SUNDAY AFTERNOON AND NIGHT. PLENTY OF UPPER LEVEL SUPPORT AS WELL AS INSTABILITY TO SUPPORT RAIN ON EITHER SIDE OF THE INVERTED TROF...SO HIGH POPS EVERYWHERE AGAIN. WITH A DECENT POTENTIAL FOR LOTS OF CLOUDS AND OFF AND ON PRECIP...SOMETHING CLOSE TO ISOTHERMAL FROM 925MB OR A FEW DEGREES WARMER THAN SEEMS IN LINE. THIS WOULD PUT HIGHS IN THE UPPER 40S TO MID 50S OVER THE NORTHERN HALF...WITH SOME LOWER 60S IN NW IA POSSIBLE IF FRONT CAN SLOW UP ENOUGH. SUNDAY NIGHT WILL SEE RAIN OVER MOST LOCATIONS AGAIN...WITH THE BEST CHANCE OVER THE SOUTHEAST HALF OF THE CWA. VERY LITTLE DIURNAL RANGE THROUGH SUNDAY NIGHT INTO MONDAY WITH AN ABUNDANCE OF LOW CLOUDS LIKELY. HIGH POPS CONTINUE RIGHT ON INTO MONDAY. && .AVIATION... AREA OF MOST CONCERN THIS MORNING IS FOCUSED ON THE SOUTHERN PART OF THE CWA...AS LOW LEVEL MOISTURE EXPANDS NORTHWARD AS EVIDENCED BY THE MVFR/IFR CIGS ACROSS MUCH OF NEBRASKA AND PORTIONS OF IOWA. SHOWERS VICINITY OF KSUX EARLY MORNING...WILL LEAD TO MVFR CIGS GETTING LOCKED IN AT KSUX BY 10Z...LOWERING TO IFR CIGS AND RAIN DURING THE AFTERNOON THROUGH TONIGHT. EASTERLY FLOW OF LOW LEVEL DRY AIR WILL KEEP KFSD VFR THRU LATE AFTERNOON AND KHON VFR INTO THE EARLY EVENING. MVFR CIGS AND RAIN INTO KFSD AFTER 14/02Z...FINALLY LOWERING TO MVFR CIGS AND RAIN AT KHON AROUND 14/04Z. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. && $$ 08/HARMON sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 257 PM CDT SAT OCT 13 2007 .DISCUSSION... HIGH PRESSURE LOCATED OVER THE OHIO VALLEY WILL SLIP TO THE EAST RCHG WRN NC 12Z MON. LTST RUC SHOWS VORT AREA ASSOCD W/ DEBRIS CLDS FROM TSTORM COMPLEX OVR MO DRFTG SEWD TO NRN TN...THUS BRINGING SOME CLDS OVR NRN TIER OF TN COUNTIES BY MIDN. PLENTY OF SUNSHINE ON TAP FOR SUNDAY WITH HIGHS RUNNING ABOUT 10 DEGS ABV NRML...NAMELY MID 70S TO LWR 80S. MSTR COMES ARND THE BACK OF THE HI AND AHEAD OF A COLD FRONT IN THE CNTRL PLNS MON...BRINGING AN INCREASE IN CLDS. WL KEEP THE HIGHEST CHC OF RAIN (50%) FOR TUESDAY AS COLD FRONT APCHS OUR RGN. THE FNT REACHES THE I-65 CORRIDOR WEDNESDAY MRNG BUT WASHES OUT...LEAVING RESIDUAL MOISTURE AND A CHC OF SHWRS ON WED. SOME DRYING OUT ON THU...WITH TEMPS ARE STILL ABOVE NORMAL. THE NEXT COLD FRONT WILL APPROACH WRN TN BY 12Z SAT...AND A 20-30% CHC OF SHWRS FOR THE RGN FRI NITE. .PRELIMINARY POINT TEMPS/POPS... NASHVILLE 52 82 56 84 / 0 0 0 0 CLARKSVILLE 49 81 55 85 / 0 0 0 10 CROSSVILLE 46 77 52 79 / 0 0 0 0 COLUMBIA 50 82 55 84 / 0 0 0 0 LAWRENCEBURG 48 82 54 84 / 0 0 0 0 WAVERLY 49 81 56 85 / 0 0 0 10 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ORCHANIAN tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE AMARILLO TX 1105 PM CDT SAT OCT 13 2007 .AVIATION... ISOLATED TO SCATTERED CONVECTION WILL OCCUR TONIGHT ALONG AND EAST OF A COLD FRONT WHICH STRETCHED FROM WEST OF KGUY TO NEAR ROMERO LINE...AND ALSO ALONG AND EAST OF A DRY LINE LOCATED FROM NEAR A KGUY TO KHRX LINE. WILL INCLUDE CONVECTION IN BOTH THE KAMA AND KGUY TAF FORECASTS THIS PACKAGE. OTHERWISE...VFR CONDITIONS WILL PREVAIL THROUGH SUNDAY NIGHT. WINDS AHEAD OF THE FRONT WILL BE FROM THE SOUTH AND SOUTHEAST AND GUSTY...BEHIND THE FRONT THE WINDS WILL BE OUT OF THE NORTH AND NORTHEAST AT 5 TO 15 KNOTS. SCHNEIDER && .PREV DISCUSSION... /ISSUED 1042 PM CDT SAT OCT 13 2007/ UPDATE... UPDATED FORECAST TO INCREASE CLOUD COVER MAINLY ACROSS THE NORTHWEST CWA. STORMS FORMING IN SOUTHERN TEXAS PANHANDLES SEEM TO MATCH UP WITH THE RUC ANALYSIS...WHICH THEN SHOWS PRECIP DEVELOPING ACROSS THE CENTRAL TO EAST CWA THROUGH 06Z OR 07Z. RECENT STORMS THAT MOVED INTO SOUTHERN KANSAS PRODUCED SEVERE HAIL SO CAN NOT RULE OUT SEVERE STORMS THROUGH THE EARLY MORNING MAINLY EAST OF A LINE FROM GUYMON TO AMARILLO. STORM MOTION WILL GENERALLY BE SOUTH TO NORTH AT AROUND 30 MPH. SO MAY ALSO SEE GUSTY WINDS WITH THESE STORMS. JJB PREV DISCUSSION... /ISSUED 704 PM CDT SAT OCT 13 2007/ AVIATION... VFR CONDITIONS WILL PREVAIL THROUGH SUNDAY WITH ONLY SCATTERED TO OVERCAST HIGH LEVEL CLOUDINESS. SOUTHERLY AND SOUTHWESTERLY WINDS TONIGHT WILL DIMINISH BY SUNSET AND THEN SHIFT TO THE NORTHWEST AND NORTH BEHIND A COLD FRONT. THE COLD FRONT WILL PUSH INTO THE NORTHWEST AND NORTHERN SECTIONS OF THE PANHANDLES LATE TONIGHT AND EARLY SUNDAY MORNING...AND WILL THEN SLOW DOWN OR STALL SUNDAY BEFORE FINALLY MOVING THROUGH THE SOUTHERN TEXAS PANHANDLE BY LATE SUNDAY AFTERNOON. SCHNEIDER PREV DISCUSSION... /ISSUED 158 PM CDT SAT OCT 13 2007/ DISCUSSION... SURFACE TROUGH/PSEUDO DRYLINE IS EDGING INTO THE WESTERN PANHANDLES NOW. DEW POINTS REMAIN IN THE MID TO UPPER 50S IN THE CENTRAL AND EASTERN PANHANDLES. POSITIVELY TILTED UPPER TROUGH IS FOUND ACROSS THE NORTHERN HIGH PLAINS INTO THE SOUTHERN GREAT BASIN. UPPER LEVEL CIRCULATION IN THE BOTTOM OF THE TROUGH IS OVER NORTHERN ARIZONA APPROACHING THE 4-CORNERS REGION. A JET STREAK HAS ROUNDED THE BOTTOM SIDE OF THE TROUGH AND IS NOW SPREADING NORTHEAST ACROSS NORTHERN NEW MEXICO INTO EASTERN COLORADO. WE FEEL THAT THUNDERSTORMS WILL STILL BE POSSIBLE ACROSS THE PANHANDLES TONIGHT. A STRENGTHENING SURFACE TROUGH UNDER AN INCREASING SOUTHWEST FLOW ALOFT WILL HELP THE WIND SHEAR AND MOISTURE WILL CONTINUE TO BE BROUGHT NORTHWARD INTO THE AREA AHEAD OF THE TROUGH. THIS SURFACE TROUGH IS ALSO EXPECTED TO MOVE EAST TONIGHT WHICH SHOULD HELP TO LIFT THE MOIST SURFACE LAYER. COOLER AIR ALOFT WILL ALSO START TO SPREAD ACROSS THE PANHANDLES AS THE UPPER TROUGH STARTS TO EMERGE ONTO THE PLAINS BY LATE TONIGHT. WITH ALL OF THIS SAID...WE STILL FEEL THAT THE PANHANDLES WILL BE LEFT ON THE DRIER AND WINDIER SIDE OF THIS SYSTEM AS IT DEVELOPS INTO A CLOSED LOW OVER NORTHERN KANSAS/SOUTHERN NEBRASKA BY SUNDAY NIGHT INTO MONDAY. THE BEST CHANCES OF PRECIP WILL STAY TO OUR NORTH AND EAST WITH THIS SYSTEM. THEREFORE...WILL KEEP OUR POPS DOWN IN THE LOWER CHANCE TO SLIGHT CHANCE CATEGORY. PRETTY MUCH FOLLOWED THE GFS/ECMWF MODELS FOR THE EARLY PART OF THIS FORECAST AS THEY SEEM TO BE HANDLING THE TRACK AND EXPECTED STRENGTH OF THIS CURRENT UPPER TROUGH. NEXT UPPER LEVEL SHORT WAVE TROUGH MOVES QUICKLY INTO THE PANHANDLES BY WEDNESDAY. HAVE GONE AHEAD AND ADDED SOME SLIGHT CHANCE POPS TO THE EASTERN PANHANDLES AS JUST ENOUGH MOISTURE MAY MAKE IT BACK TO POSE A THREAT FOR SHRA/TSRA. TYPICAL OCTOBER WINDY AND MILD WEATHER WILL CONTINUE BEYOND MID WEEK NEXT WEEK. ANOTHER COLD FRONT MAY ARRIVE BY NEXT THURSDAY NIGHT...BUT THIS ONE APPEARS DRY AT THIS TIME. FIRE WEATHER... RELATIVE HUMIDITIES WILL INCREASE THROUGH THE EVENING...SO WILL LET THE FIRE DANGER STATEMENT RUN ITS COURSE. WILL HAVE TO WATCH THE WINDS ON SUNDAY AS THE FRONT APPROACHES. IF THE FRONT IS DELAYED SOME SUNDAY AFTERNOON...THEN THE WINDS MAY BE A LITTLE STRONGER AHEAD OF IT AND RELATIVE HUMIDITIES WILL BE LOW. ALSO WINDS COULD SHIFT QUITE ABRUPTLY FROM THE SOUTHWEST TO THE NORTH ALONG THE FRONT...SO THIS COULD CAUSE SOME PROBLEMS FOR ANY ONGOING FIRES. AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. $$ AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. $$ && .AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. && $$ 11/14 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE AMARILLO TX 1042 PM CDT SAT OCT 13 2007 .UPDATE... UPDATED FORECAST TO INCREASE CLOUD COVER MAINLY ACROSS THE NORTHWEST CWA. STORMS FORMING IN SOUTHERN TEXAS PANHANDLES SEEM TO MATCH UP WITH THE RUC ANALYSIS...WHICH THEN SHOWS PRECIP DEVELOPING ACROSS THE CENTRAL TO EAST CWA THROUGH 06Z OR 07Z. RECENT STORMS THAT MOVED INTO SOUTHERN KANSAS PRODUCED SEVERE HAIL SO CAN NOT RULE OUT SEVERE STORMS THROUGH THE EARLY MORNING MAINLY EAST OF A LINE FROM GUYMON TO AMARILLO. STORM MOTION WILL GENERALLY BE SOUTH TO NORTH AT AROUND 30 MPH. SO MAY ALSO SEE GUSTY WINDS WITH THESE STORMS. JJB && .PREV DISCUSSION... /ISSUED 704 PM CDT SAT OCT 13 2007/ AVIATION... VFR CONDITIONS WILL PREVAIL THROUGH SUNDAY WITH ONLY SCATTERED TO OVERCAST HIGH LEVEL CLOUDINESS. SOUTHERLY AND SOUTHWESTERLY WINDS TONIGHT WILL DIMINISH BY SUNSET AND THEN SHIFT TO THE NORTHWEST AND NORTH BEHIND A COLD FRONT. THE COLD FRONT WILL PUSH INTO THE NORTHWEST AND NORTHERN SECTIONS OF THE PANHANDLES LATE TONIGHT AND EARLY SUNDAY MORNING...AND WILL THEN SLOW DOWN OR STALL SUNDAY BEFORE FINALLY MOVING THROUGH THE SOUTHERN TEXAS PANHANDLE BY LATE SUNDAY AFTERNOON. SCHNEIDER PREV DISCUSSION... /ISSUED 158 PM CDT SAT OCT 13 2007/ DISCUSSION... SURFACE TROUGH/PSEUDO DRYLINE IS EDGING INTO THE WESTERN PANHANDLES NOW. DEW POINTS REMAIN IN THE MID TO UPPER 50S IN THE CENTRAL AND EASTERN PANHANDLES. POSITIVELY TILTED UPPER TROUGH IS FOUND ACROSS THE NORTHERN HIGH PLAINS INTO THE SOUTHERN GREAT BASIN. UPPER LEVEL CIRCULATION IN THE BOTTOM OF THE TROUGH IS OVER NORTHERN ARIZONA APPROACHING THE 4-CORNERS REGION. A JET STREAK HAS ROUNDED THE BOTTOM SIDE OF THE TROUGH AND IS NOW SPREADING NORTHEAST ACROSS NORTHERN NEW MEXICO INTO EASTERN COLORADO. WE FEEL THAT THUNDERSTORMS WILL STILL BE POSSIBLE ACROSS THE PANHANDLES TONIGHT. A STRENGTHENING SURFACE TROUGH UNDER AN INCREASING SOUTHWEST FLOW ALOFT WILL HELP THE WIND SHEAR AND MOISTURE WILL CONTINUE TO BE BROUGHT NORTHWARD INTO THE AREA AHEAD OF THE TROUGH. THIS SURFACE TROUGH IS ALSO EXPECTED TO MOVE EAST TONIGHT WHICH SHOULD HELP TO LIFT THE MOIST SURFACE LAYER. COOLER AIR ALOFT WILL ALSO START TO SPREAD ACROSS THE PANHANDLES AS THE UPPER TROUGH STARTS TO EMERGE ONTO THE PLAINS BY LATE TONIGHT. WITH ALL OF THIS SAID...WE STILL FEEL THAT THE PANHANDLES WILL BE LEFT ON THE DRIER AND WINDIER SIDE OF THIS SYSTEM AS IT DEVELOPS INTO A CLOSED LOW OVER NORTHERN KANSAS/SOUTHERN NEBRASKA BY SUNDAY NIGHT INTO MONDAY. THE BEST CHANCES OF PRECIP WILL STAY TO OUR NORTH AND EAST WITH THIS SYSTEM. THEREFORE...WILL KEEP OUR POPS DOWN IN THE LOWER CHANCE TO SLIGHT CHANCE CATEGORY. PRETTY MUCH FOLLOWED THE GFS/ECMWF MODELS FOR THE EARLY PART OF THIS FORECAST AS THEY SEEM TO BE HANDLING THE TRACK AND EXPECTED STRENGTH OF THIS CURRENT UPPER TROUGH. NEXT UPPER LEVEL SHORT WAVE TROUGH MOVES QUICKLY INTO THE PANHANDLES BY WEDNESDAY. HAVE GONE AHEAD AND ADDED SOME SLIGHT CHANCE POPS TO THE EASTERN PANHANDLES AS JUST ENOUGH MOISTURE MAY MAKE IT BACK TO POSE A THREAT FOR SHRA/TSRA. TYPICAL OCTOBER WINDY AND MILD WEATHER WILL CONTINUE BEYOND MID WEEK NEXT WEEK. ANOTHER COLD FRONT MAY ARRIVE BY NEXT THURSDAY NIGHT...BUT THIS ONE APPEARS DRY AT THIS TIME. FIRE WEATHER... RELATIVE HUMIDITIES WILL INCREASE THROUGH THE EVENING...SO WILL LET THE FIRE DANGER STATEMENT RUN ITS COURSE. WILL HAVE TO WATCH THE WINDS ON SUNDAY AS THE FRONT APPROACHES. IF THE FRONT IS DELAYED SOME SUNDAY AFTERNOON...THEN THE WINDS MAY BE A LITTLE STRONGER AHEAD OF IT AND RELATIVE HUMIDITIES WILL BE LOW. ALSO WINDS COULD SHIFT QUITE ABRUPTLY FROM THE SOUTHWEST TO THE NORTH ALONG THE FRONT...SO THIS COULD CAUSE SOME PROBLEMS FOR ANY ONGOING FIRES. AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. $$ && .AMA WATCHES/WARNINGS/ADVISORIES... TX...NONE. OK...NONE. && $$ 11/14 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 1242 AM CDT SAT OCT 13 2007 .AVIATION... WINDS WILL BE BIGGEST AVIATION CONCERNS TODAY WITH SUSTAINED WINDS AVERAGING 15KT WITH GUSTS TO NEAR AND POSSIBLY GREATER THAN 25KT. KEPT IN LLWS FOR KMAF BASED ON VAD AND PROFILE DATA...BUT MAY HAVE TO ADD IT TO OTHER SITES LATER. EXPECT WINDS TO BE OUT OF THE S/SSE FOR ALL TERMINALS EXCEPT KCNM WHERE A WESTERLY PUSH WILL OCCUR AHEAD OF THE UPPER LEVEL SYSTEM MOVING TOWARDS THE AREA. VFR CONDITIONS EXPECTED AREAWIDE TODAY. && .PREV DISCUSSION... /ISSUED 933 PM CDT FRI OCT 12 2007/ UPDATE... WATER VAPOR AND INFRARED IMAGERY CONTINUE TO SHOW UPPER LEVEL JET STREAK OVER SOUTHERN NEW MEXICO. IT DOES NOT APPEAR THAT THIS WILL HAVE ANY AFFECT ON FUTURE WEATHER CONDITIONS NEAR THE SURFACE AS THERE IS NOT MUCH...IF ANY...EVIDENCE OF WEAK MID LEVEL EMBEDDED WAVES WITH IT. AT THE SURFACE...WINDS CONTINUE TO HOLD OVER MUCH OF THE CENTRAL AND EASTERN PORTIONS OF THE CWA AS MODERATE PRESSURE GRADIENT HAS ORIENTED ITSELF FROM SOUTHEAST NEW MEXICO TO SOUTHERN TEXAS IN RESPONSE TO APPROACHING UPPER JET AND LEE TROUGHING. FOR THIS REASON...SOME LOCATIONS WILL NOT RADIATE AS WELL WITH THE ENHANCED MIXING AND LOW TEMPS WERE ADJUSTED ACCORDINGLY. THE RUC/WRF DEWPOINTS WERE...AND ARE...TOO HIGH PROBABLY DUE TO INCREASING SOUTHWEST FLOW JUST ABOVE BOUNDARY LAYER. THIS RESULTED IN OVERFORECASTED INSTABILITY AND A TIGHTER DRYLINE GRADIENT THAN WHAT WAS ACTUALLY OBSERVED THROUGHOUT THE REGION TODAY. AS A RESULT...CONVECTION WAS UNABLE TO DEVELOP THIS AFTERNOON WITH MINIMAL SUPPORT ALOFT AND WEAK SURFACE CONVERGENCE. A SHOWER OVER THE EXTREME NORTHERN CWA IS NOT OUT OF THE QUESTION AS UPPER JET STREAK APPROACHES TONIGHT...BUT COVERAGE WILL BE ISOLATED AT BEST. WILL PULL THE POPS FROM THE FORECAST...BUT IF ANYTHING DOES DEVELOP WILL HANDLE IT WITH SHORT TERM FORECASTS. TWEAKED WIND...DEWPOINT... AND SKY GRIDS ACCORDING TO TRENDS. UPDATE WILL FOLLOW SHORTLY. && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ 13 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1131 PM CDT FRI OCT 12 2007 .AVIATION... LITTLE CHANGE FROM 00Z TAFS REGARDING 06Z TAF. VFR CONDS THRU 24 HRS...THOUGH SOME CI ANVIL BLOWOFF MAY OCCUR LATE ARND D/FW SITES FROM SCT STORMS WELL TO THE NW. NAM STILL TRYING TO MVFR CIGS ARND 12Z SAT A.M AT KACT...BUT IT`S THE OUTLIER. LEANING TWD GFS/RUC SOLNS OF STRATUS STAYING W/SW OF THE AIRPORT. OTRW...SELY FLOW 5-9 KTS OVRNGT...THEN W/MIXING AFTER 15Z...SLY WNDS 13-16KT WITH GSTS 20-25 KTS...BEFORE GOING BACK SELY ARND 10 KTS BY 00Z SUN/AFTR. && .PREV DISCUSSION... /ISSUED 931 PM CDT FRI OCT 12 2007/ UPDATE... 00Z FWD AND AREA UPPER AIR SOUNDINGS STILL INDICATE THAT DRY AIR IS IN PLACE ACROSS THE REGION. HOWEVER...THERE HAS BEEN A SLIGHT INCREASE IN MOISTURE ACROSS THE WESTERN PORTIONS ON THE CWA AS CAN BE SEEN IN THE DEWPOINTS. THE GULF OF MEXICO WILL REMAIN CLOSED OVERNIGHT SO DO NOT EXPECT ANY MORE DRASTIC CHANGES IN MOISTURE ACROSS THE AREA. HAVE ADJUSTED TEMPERATURES DOWN A DEGREE OR TWO IN MOST LOCATIONS BASED ON CURRENT TRENDS AND COMPARISON WITH ATMOSPHERIC TRENDS FROM LAST NIGHT. OVERNIGHT LOWS WILL STILL BE WARMER...ESPECIALLY OUT WEST. DID DROP OVERNIGHT LOWS IN THE SOUTHEAST BY AS MUCH AS 4 DEGREES AS CURRENT TEMPERATURES ARE ALREADY RUNNING IN THE MID 60S AND PREVIOUS FORECAST HAD LOWER 60S FOR OVERNIGHT LOWS. OTHERWISE...ONLY CHANGES TO GRIDS WERE COSMETIC TO ACCOUNT FOR RECENT TRENDS. 82/JLD PREV DISCUSSION... /ISSUED 612 PM CDT FRI OCT 12 2007/ AVIATION... WILL HOLD TO CURRENT THEME OF OVERALL VFR CONDS THRU 00Z SUN (SAT EVE). HOWEVER...WILL NEED TO WATCH KACT VCNTY FOR SOME BRIEF MVFR CIGS BETWEEN 10-14Z PER LATEST BL MSTR PROGS...AS 30-40 KT LLJ DVLPS OFF JUST TO OUR IMMEDIATE NNW AFTER 06Z SAT. OTRW...AGREE WITH CWSU DISC OF SE WNDS 7-11 KTS...BECMB SLY AND INCRSG 10-20 KTS AFTR 12Z SAT...THEN 15-25 KTS/GSTY BY 17Z SAT/AFTR. PREV DISCUSSION... /ISSUED 305 PM CDT FRI OCT 12 2007/ SHORT TERM (TONIGHT)...DRY CONDITIONS EXPECTED AGAIN THIS EVENING AND TONIGHT AS HIGH PRESSURE REMAINS IN PLACE JUST EAST OF THE AREA. TEMPS WILL BE A FEW DEGREES WARMER OVERNIGHT...ESPECIALLY OVER THE WEST WHERE MOISTURE CONTENT IS A LITTLE HIGHER. ANY PRECIP SHOULD STAY WELL TO THE NORTH OF THE REGION. 91/DUNN LONG TERM (SATURDAY THROUGH FRIDAY)...UPPER LEVEL TROUGH WILL SWING THROUGH THE FOUR CORNERS REGION SATURDAY AND CAUSE A SURFACE LOW TO DEEPEN IN THE PLAINS. THIS WILL RESULT IN INCREASING CLOUDS AND WINDS...WITH BREEZY CONDITIONS EXPECTED SUNDAY. THE WINDS WILL USHER IN LOW LEVEL GULF MOISTURE TO THE REGION AND LOW TEMPERATURES SATURDAY AND SUNDAY NIGHTS WILL BE MUCH WARMER THAN RECENT NIGHTS. AS THE TROUGH EJECTS OUT INTO THE PLAINS SUNDAY A DRY LINE WILL ORGANIZE TO THE WEST. MODELS ARE USUALLY TOO FAST/FAR EAST WITH DRY LINE MOVEMENT...AND BELIEVE THAT THE BRUNT OF CONVECTION WILL BE NORTHWEST OF THE CWA THROUGH SUNDAY EVENING. BY THE NIGHT TIME HOURS SUNDAY...STORMS WILL BEGIN TO WANDER EAST/SOUTHEAST AND REACH THE NW AND NRN ZONES. A PACIFIC COLD FRONT WILL OVERTAKE THE DRY LINE BY MONDAY MORNING BUT AS THE UPPER LEVEL TROUGH BEGINS TO LIFT OUT...THE FRONT WILL LOSE ITS SOUTHEASTWARD MOMENTUM AND STALL ACROSS NORTH TEXAS MONDAY AFTERNOON. MONDAY PROBABLY REPRESENTS THE PERIOD WITH THE BEST CHANCE OF RAIN AS THE AIRMASS WILL BE MOIST AND UNSTABLE WITH THE FRONT IN THE AREA. SYNOPTIC FORCING WILL ALSO BE PRESENT MONDAY AS A FINAL PIECE OF POTENTIAL VORTICITY SLIDES ACROSS. BY MONDAY NIGHT AND TUESDAY...DESPITE THE LINGERING FRONT...UPPER LEVEL RIDGING WILL BUILD IN ACROSS NORTH TEXAS WHICH SHOULD RESULT IN SUBSIDENCE AND LITTLE TO NO CHANCE OF RAIN. OVERALL...THE MEX MOS APPEARS REASONABLE FOR TEMPS THROUGH THE NEXT WEEK AND DEVIATIONS WERE MINOR. TEMPERATURES WILL BE SLIGHTLY ABOVE NORMAL FOR LOWS...AND WELL ABOVE NORMAL FOR HIGHS DUE TO PLENTIFUL SUNSHINE. MODELS CONTINUE TO DISPLAY LOW CONFIDENCE IN THE EXTENDED BUT SEEM TO BE TRENDING TOWARD A FARTHER NORTHWARD SOLUTION OF THE UPPER TROUGH. FOR THIS REASON WILL KEEP FORECAST WARM/DRY THROUGH FRIDAY. TR.92 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 86 64 88 67 84 / 10 0 0 0 10 WACO, TX 86 63 87 66 85 / 10 0 0 0 10 PARIS, TX 81 53 83 59 82 / 10 0 0 0 10 DENTON, TX 85 59 88 67 83 / 10 0 0 0 10 MCKINNEY, TX 82 58 85 64 84 / 10 0 0 0 10 DALLAS, TX 82 63 86 67 84 / 10 0 0 0 10 TERRELL, TX 82 59 85 64 84 / 10 0 0 0 10 CORSICANA, TX 84 61 85 63 84 / 10 0 0 0 10 TEMPLE, TX 86 61 87 67 85 / 10 0 0 0 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 82/05 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 933 PM CDT FRI OCT 12 2007 .UPDATE... WATER VAPOR AND INFRARED IMAGERY CONTINUE TO SHOW UPPER LEVEL JET STREAK OVER SOUTHERN NEW MEXICO. IT DOES NOT APPEAR THAT THIS WILL HAVE ANY AFFECT ON FUTURE WEATHER CONDITIONS NEAR THE SURFACE AS THERE IS NOT MUCH...IF ANY...EVIDENCE OF WEAK MID LEVEL EMBEDDED WAVES WITH IT. AT THE SURFACE...WINDS CONTINUE TO HOLD OVER MUCH OF THE CENTRAL AND EASTERN PORTIONS OF THE CWA AS MODERATE PRESSURE GRADIENT HAS ORIENTED ITSELF FROM SOUTHEAST NEW MEXICO TO SOUTHERN TEXAS IN RESPONSE TO APPROACHING UPPER JET AND LEE TROUGHING. FOR THIS REASON...SOME LOCATIONS WILL NOT RADIATE AS WELL WITH THE ENHANCED MIXING AND LOW TEMPS WERE ADJUSTED ACCORDINGLY. THE RUC/WRF DEWPOINTS WERE...AND ARE...TOO HIGH PROBABLY DUE TO INCREASING SOUTHWEST FLOW JUST ABOVE BOUNDARY LAYER. THIS RESULTED IN OVERFORECASTED INSTABILITY AND A TIGHTER DRYLINE GRADIENT THAN WHAT WAS ACTUALLY OBSERVED THROUGHOUT THE REGION TODAY. AS A RESULT...CONVECTION WAS UNABLE TO DEVELOP THIS AFTERNOON WITH MINIMAL SUPPORT ALOFT AND WEAK SURFACE CONVERGENCE. A SHOWER OVER THE EXTREME NORTHERN CWA IS NOT OUT OF THE QUESTION AS UPPER JET STREAK APPROACHES TONIGHT...BUT COVERAGE WILL BE ISOLATED AT BEST. WILL PULL THE POPS FROM THE FORECAST...BUT IF ANYTHING DOES DEVELOP WILL HANDLE IT WITH SHORT TERM FORECASTS. TWEAKED WIND...DEWPOINT... AND SKY GRIDS ACCORDING TO TRENDS. UPDATE WILL FOLLOW SHORTLY. && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ 67/99 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 1143 AM CDT FRI OCT 12 2007 .UPDATE... VISIBLE IMAGERY SUPPORTS MODEL FCST OF STEEP MID LEVEL LR/S WITH ACCASS NOTED ACRS PB MAINLY W OF KMAF. MEANWHILE WATER IMAGERY INDICATES A MINOR SHRTWV TROF/SPEED MAX IN WRN NM AHEAD OF UPPER LOW IN CALIF. LOW LEVEL MOIST AXIS IS ALSO ORIENTED N-S ACRS THE PB INTO THE PANHANDLE. BASED MODIFIED 12Z MAF SOUNDING FOR CURRENT CONDITIONS (24C/17C) THERE IS SUBSTANTIAL SB CINH THAT WILL HAVE TO BE ERODED FOR TSTM FORMATION. BY 21Z THE RUC SUPPORTS BREAKABLE CAP ACRS PB AND WITH HIGH TEMPS IN THE MID TO UPPER 80S TODAY A MODIFIED 12Z KMAF SOUNDING ALSO SUPPORTS BREAKABLE CAP. 0-6KM BULK SHEAR WILL INCREASE TO NEAR 35KT BY 21Z AND 7H-5H NEAR 7 C/KM ISOLD SEVERE TSTMS WILL BE POSSIBLE. AFOREMENTIONED SHRTWV TROF WILL PROBABLY TOO FAR NW-N TO ENHANCE LIFT FROM SFC HEATING. FAVORED AREA LOOKS TO BE NORTH OF A LINE FROM CNM...PEQ...MAF...GGS. WILL OPT TO USE SOME OF THE 12Z METMOS FOR WINDS WHICH ARE A LITTLE STRONGER THAN CURRENT FCST. WILL SEND UPDATE WITHIN AN HOUR. && .AVIATION... LOW END RISK OF TSTMS IN TAFS WITH VFR CONDITIONS EXPECTED THRU AT LEAST 00Z. OTHERWISE LOW LEVEL JET WILL DEVELOP EARLY EVENING AND WINDS WILL REMAIN ABOVE 12KTS THRU THE NIGHT...EXCEPT CNM/INK. EXPECT THAT WITH WINDS REMAINING UP PATCHY MVFR FOG OF LAST FEW MORNINGS WILL NOT OCCUR SAT MORNING. MVFR CIGS POSSIBLE AFTER 06Z INVOF HOB NWD. && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SPOKANE WA 434 PM PDT FRI OCT 12 2007 .SYNOPSIS... A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE AREA THIS WEEKEND FOR WARMER TEMPERATURES AND DRY CONDITIONS. A SERIES OF SYSTEMS IS EXPECTED TO AFFECT THE AREA NEXT WEEK BRINGING PERIODS OF UNSETTLED CONDITIONS. && .DISCUSSION... UPDATED AVIATION DISCUSSION. TONIGHT...WEAK UPPER LEVEL TROF EXPECTED TO CROSS THE INLAND NW OVERNIGHT WITH A GRADUAL CLEARING TREND BEHIND IT. THE LATEST SATELLITE IMAGERY STILL SHOWING PLENTY OF CLOUDS AND MOISTURE AHEAD OF THE TROF...WHICH WAS CURRENTLY PUSHING INTO NW WASHINGTON. DESPITE THE CLOUDINESS...PRECIPITATION HAS BECOME RATHER LIMITED OVER THE PAST SEVERAL HOURS AS THE LOW-LEVEL ISENTROPIC ASCENT HAS FIZZLED WITH A TRANSITION TO INCREASINGLY WESTERLY FLOW VERSUS THE SOUTHERLY FLOW EARLIER THIS MORNING. MAIN FORECAST CHALLENGE FOR TONIGHT WILL BE MIN TEMPS AND CHANCES FOR FOG. GIVEN THE TRACK AND SPEED OF THE UPPER LEVEL TROF AND ITS ASSOCIATED DRYING...WE EXPECT THE CLEAREST SKIES TO AFFECT THE WESTERN ZONES...WHEREAS CLOUDS COULD CONCEIVABLY HANG OVER THE IDAHO PANHANDLE...ESPECIALLY THE CENTRAL PORTIONS OF IT. FOR THIS REASON WE GENERALLY WENT ABOVE MOS TEMPS OVER THE SOUTHEAST THIRD OF THE CWA AND WENT WITH MOS VALUES ELSEWHERE. FOG COULD BE A CONCERN LATE TONIGHT NEAR THE CASCADES...WENATCHEE AREA...OKANOGAN VALLEY DUE TO TODAYS RAINFALL. DEWPOINT FORECASTS OFF THE GFS AND NAM ARE WOEFULLY UNDERDONE...WHILE THE RUC IS DOING MUCH BETTER. WHILE THE NAM AND GFS INDICATE WE WILL BE FAR FROM SATURATION LATE TONIGHT IN THESE AREAS...WE HAVE TO WONDER WHAT WILL REALLY TRANSPIRE. UNFORTUNATELY THE RUC GUIDANCE DOES NOT YET EXTEND TO THE LATE NIGHT PORTION OF THE FORECAST YET. FOR NOW WE WILL KEEP FOG OUT OF THE FORECAST...BUT WILL GO FOR HIGHER HUMIDITIES THAN IS FORECAST BY THE NAM AND GFS. FX SATURDAY THROUGH MONDAY...MODELS IN GOOD AGREEMENT THROUGH THIS FORECAST PERIOD. UPPER LEVEL HIGH PRESSURE WILL BUILD INTO THE INLAND NORTHWEST THIS WEEKEND FOR MOSTLY CLEAR SKIES AND WARMING AFTERNOON TEMPERATURES. ON MONDAY...THE COLD FRONT THAT IS NOW WELL OFFSHORE SOUTH OF THE ALEUTIANS BTWN 150-170W. THIS FRONT WILL AID IN PUSHING THE RIDGE EAST OF OUR AREA...BUT AS THE FRONT ENCOUNTERS THE RIDGE IS WILL STRETCH...WEAKEN...AND SLOW DOWN. TIMING OF FRONT WILL BE CRITICAL TO HIGH TEMPERATURES ON MONDAY...GIVING OVERALL LOW CONFIDENCE FOR HIGH TEMPS MONDAY. RIGHT NOW...TIMING LOOKS TO BE NEAR THE CASCADES MONDAY AFTERNOON...WHICH SHOULD LEAD TO SOME COOLING COMPARED TO SUNDAY OVER CENTRAL WA ALONG WITH A CHANCE OF RAIN NEAR THE CASCADES...WHILE EASTERN WA/ID SHOULD SEE SOME WARMING. JW MONDAY NIGHT THROUGH FRIDAY...MODELS STILL LACKING CONSENSUS WITH THE TIMING OF A STRING OF PACIFIC WAVES POISED TO AFFECT THE REGION DURING THE EXTENDED PERIOD. THE GFS SOLUTION CONTINUES TO BE FASTER THAN MOST OTHER GUIDANCE. HPC FAVORS THE SLOWER ECMWF/GEFS ENSEMBLE MEAN TIMING. THE SLOWER TIMING WILL LIMIT PRECIPITATION TO THE CASCADES ON MONDAY THEN SPREAD EAST ACROSS THE FORECAST AREA OVERNIGHT AS A STRONG COLD FRONT IS PUSHED THROUGH THE REGION WITH THE HELP OF A 160KT PACIFIC JET. THE TIMING AND TRACK OF THE NEXT SYSTEM IS ALSO UNDER QUESTION. THIS IS WHERE GUIDANCE DIFFERS SIGNIFICANTLY. GFS TRACKS A STRONG SURFACE LOW JUST OFF THE WASHINGTON COAST AND INTO SOUTHERN BC ON THURSDAY WITH 850MB WINDS NEAR 50KT OVER THE INLAND NORTHWEST ALTHOUGH THE LATEST RUN HAS ADJUSTED THE TRACK A BIT FARTHER NORTH THAN PREVIOUS RUNS. BOTH THE ECMWF AND CANADIAN ENSEMBLES KEEP THE LOW FARTHER NORTH WITH THE TRAILING COLD FRONT AND STRONG WINDS ARRIVING ON FRIDAY. AT THIS POINT WILL CONTINUE WITH BREEZY CONDITIONS STARTING ON THURSDAY AND CONTINUING FRIDAY BUT THIS WILL NEED TO BE MONITORED CLOSELY. TEMPERATURES WILL CONTINUE A DOWNWARD TREND THROUGH THE EXTENDED FORECAST PERIOD WITH CLOUDY AND UNSETTLED CONDITIONS KEEPING DAYTIME READINGS SEVERAL DEGREES BELOW SEASONAL NORMALS. /KELCH && .AVIATION... A WEAK SYSTEM WILL SLOWLY EXIT THE AREA THROUGH 18Z SATURDAY...WITH SKIES SLOWLY CLEARING FROM WEST TO EAST AFTER 03Z TONIGHT. HOWEVER DESPITE BKN-OVC SKIES CIGS WILL REMAIN VFR AT ALL TAF SITES. A VERY MOIST AIR MASS OVER THE WESTERN PORTION OF THE FORECAST AREA FROM RAIN THIS MORNING LEADS TO SOME CONCERN FOR PATCHY FOG AFT 10Z TONIGHT AS CLOUD COVER DIMINISHES. EXPECT FOG FORMATION IN THE VALLEYS OF OKANOGAN HIGHLANDS AND THE NORTHERN CASCADES...POSSIBLY AFFECTING VALLEYS AS FAR SOUTH AS KEAT BUT THERE SHOULD BE ENOUGH OF A NW WIND TO KEEP FOG FROM DEVELOPING AT THE TAF SITE. EK && .PRELIMINARY POINT TEMPS/POPS... SPOKANE 41 63 40 65 43 66 / 10 0 0 0 0 0 COEUR D`ALENE 41 63 40 66 43 69 / 10 0 0 0 0 0 PULLMAN 42 64 37 67 41 69 / 10 0 0 0 0 0 LEWISTON 45 67 44 69 46 70 / 10 0 0 0 0 0 COLVILLE 38 67 37 68 39 67 / 10 0 0 0 0 10 SANDPOINT 38 63 36 64 37 67 / 10 0 0 0 0 0 KELLOGG 37 61 38 63 40 65 / 10 0 0 0 0 0 MOSES LAKE 43 67 38 69 41 66 / 10 0 0 0 0 10 WENATCHEE 43 67 43 66 47 63 / 10 0 0 0 0 10 OMAK 40 68 36 66 41 63 / 10 0 0 0 0 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...NONE. WA...NONE. && $$ wa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 351 AM CDT FRI OCT 12 2007 .DISCUSSION...FCST FOCUS IS ON SHORT TERM PCPN TRENDS WITH APPCH VORT...THEN FROST POTENTIAL TNGT AND THEN ON WAA PCPN TRENDS SAT NGT/SUNDAY. WATER VAPOR/RUC ANIMATION SHOWS 20 UNIT SHORTWAVE APPCH FROM WRN MN. MODELS HAVE THIS COMING ACRS THE CWA THIS MRNG. GFS AND NAM NOT DOING MUCH WITH THIS FEATURE. APPEARS BETTER COVERAGE OF PCPN TRENDING INTO NRN WI...THOUGH STILL ISOLD RETURNS SOUTH OF MPX. MOISTURE AND INSTABILTY CONSIDERATIONS ARE NOT FAVORING MUCH OF THIS MAKING IT ACRS OUR CWA THIS MRNG. PCPN WITH THIS VORT IS PROGRESSING AND WILL PUT ISOLD SHRA INTO NW CWA FIOR THIS MRNG. CLOUDS WILL BE TRICKY TODAY WITH SYS CLOUDS AND LINGERING LOW CLOUDS STILL BOTHERSOME. NEXT CONCERN IS FROST POTENTIAL TONIGHT. SFC RDG AXIS PROGGD TO BE LAID OUT ACRS THE CWA. OVERALL PLACEMENT OF GOING FROST IN GRIDS LOOKS GOOD AND WILL NOT DEVIATE. AM NOT CONVINCED ENUF TO GO WITH HEADLINES AT THIS POINT GIVEN ONGOING CLOUD TRENDS AND THE FACT THAT BOTH THE GFS AND NAM SHOW SOME LLVL RH HANGING ARND STILL TNGT. JUST NOT A SLAM DUNK AT THIS POINT SO WILL HOLD OFF FOR NOW. HOWEVER...WILL MAINTAIN FROST POTENTIAL IN HWO. SATURDAY LOOKS TO BE A QUIET DAY WITH INFLUENCE OF SFC AND H8 RIDGE AXIS. FOCUS THEN SHIFTS TO WAA SAT NGT INTO SUNDAY. BASED ON CONSENSUS OF PROGS WILL START TO BRING LIGHT PCPN INTO CWA SAT NGT AFTER MIDNIGHT. THIS PRETTY MUCH IN LINE WITH GOING WX GRIDS. THE NAM IS SHOWING MORE RESPECT FOR THE DRY INFLUENCE OF HIGH WHILE THE GFS IS MOST BULLISH ON EXTENT AND AMOUNT OF QPF. THE LOCAL WRF20 AND CANADIAN IS A NICE COMPROMISE BLEND. THE NAM APPEARS TO BE THE OUTLIER GETTING INTO MON SO WILL FOLLOW CLOSER WITH THE GFS/CANADIAN AND ECMWF WITH A WETTER SOLUTION. WILL RAISE POPS TO LIKELY SUN INTO MON. IF 00Z HI RES ECMWF IS RIGHT...PCPN COULD LINGER LONGER ON TUESDAY. TOOK SLGT CHC UP TO CHC FOR NOW. && 10 .AVIATION....AVIATION...MID LEVEL CLOUDS AND LIGHT WINDS IN LOW LEVELS WILL POSTPONE STRATUS EROSION FOR A TIME BUT IN GENERAL VFR CIGS EXPCD WITH INCRG NWLY WNDS AT LWR LEVELS ENCOURAGING MORE WDSPRD CLEARING FOR TNGT. WL NEED TO KEEP ONE EYE ON LAKESHORE AREAS FOR POTENTIAL OF LOW ST DVLPING OVR COOLER NEARSHORE WATERS AND BRUSHING INLAND AREAS /KMKE/ FOR A TIME THIS MRNG. && .MKX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 347 AM CDT FRI OCT 12 2007 .SHORT TERM...THROUGH SUNDAY NIGHT MUCH OF THE TIME THIS MORNING SPENT ON WET WEEKEND WEATHER SYSTEM SET TO MOVE INTO THE AREA...AND SOME TIME ALSO SPENT ON WEAK WAVE CAUSING A FEW SHOWERS THIS MORNING TO OUR NORTHWEST. CURRENTLY...SURFACE RIDGE AXIS REMAINS PARKED OVER FORECAST AREA IN WAKE OF DOUBLE-BARRELED DEEP VORTEX FROM SRN HUDSONS BAY INTO NEW ENGLAND. PESKY MID LEVEL WAVE...WHICH IS THE SRN COMPONENT OF A MUCH STRONGER WAVE EJECTING INTO CNTL CANADA...HAS BROKE AWAY FROM ITS PARENT WAVE AND CRESTED THE MEAN CNTL CONUS RIDGE AND DRIVING SOUTHEAST ACROSS THE AREA THIS MORNING INTO CONFLUENT FLOW TO THE SOUTHWEST OF THE HUDSON VORTEX. RADAR MOSAICS SHOW PLENTY OF WEAK ECHOES ACROSS MN/WI THIS MORNING...AND EVEN A FEW LIGHTNING STROKES. SEVERAL SITES IN MPX FORECAST AREA RECEIVING TRACE AMOUNTS...BUT VERY FEW MEASURING. GOES FOG PRODUCTS SHOWS WIDESPREAD 4-8KFT CEILINGS WITH THIS WAVE...WITH BAND OF COOLER/ENHANCED TOPS ASSOCIATED WITH THE STRONGEST RETURNS ON RADAR ON MN/WI BORDER AT 08Z. FIRST CONCERN FOR THE FORECAST IS THE PESKY WAVE THIS MORNING. 12.06 RUC AND 12.00 WRF MODELS SHOWING BEST PV ADVECTION ON 1.5 PV SURFACE MOVING THROUGH AREA RIGHT NOW IN LEFT EXIT REGION OF 80KT JETLET ON SAID SURFACE. WAVE NOT STRONG ENOUGH TO DISTURB THE SFC-2KM LAYER MUCH...HOWEVER WEAK/TRANSIENT MID LEVEL FRONTOGENETICAL BANDS EVIDENT IN THE SHORT TERM/HIGHER RESOLUTION DATA SETS LIKELY OWING TO RESPONSE OF THE PV ANOMALY AS IT SHIFTS ACROSS THE AREA...WHICH SEEMS TO LINE UP VERY WELL WITH AREA OF SPRINKLES/SHRA RIGHT NOW. WHILE MUCH OF THE FORCING WILL EXIT BY SUNRISE...STILL SEE ENOUGH RESIDUAL 700-600MB LEVEL FRONTOGENETICAL FORCING AND WEAK DYNAMICS FOR SPRINKLE/SHRA INCLUSION MAINLY NORTH OF I-90 THROUGH THE MORNING. PLENTY OF CLOUDS IN WAKE OF SYSTEM...WITH WEAK FLOW. DEVELOPING WARM ADVECTION TO OUR WEST...LACK OF STRONG SUBSIDENCE IN WAKE OF THIS WAVE...AND OVERALL WEAK FLOW SIGNALS MORE CLOUDS THAN NOT HANGING ON THROUGH THE DAY. LOWERED HIGHS A BIT BASED ON THIS. QUIET THROUGH SATURDAY AS THE HIGH PRESSURE SHIFTS OFF TO THE EAST. MIX OF CLOUDS AND SUN SATURDAY...AFTER CLOUDS SLOWLY BREAK UP OVERNIGHT TONIGHT. TEMPERATURES QUITE SEASONABLE. NEXT STRONG TROUGH CURRENTLY OFF CALI COAST MOVES INTO THE GREAT BASIN AND OUT INTO THE PLAINS ON SATURDAY. BECOMING QUITE CLEAR NOW THAT FORECAST AREA WILL BE AFFECTED BY BOTH WARM ADVECTION PRECIPITATION EVENT SATURDAY NIGHT THROUGH SUNDAY...THEN DEVELOPING DEFORMATION/UPPER LEVEL PV ANOMALY SUNDAY NIGHT INTO MONDAY AND PERHAPS BEYOND. ADDED SOME DETAIL TO SATURDAY NIGHT WHICH BRINGS RAIN SHIELD INTO SRN FORECAST AREA IN THE EARLY-MID EVENING HOURS...THEN SPREADS NORTH SLOWLY OVERNIGHT ON NOSE OF 40KT LOW LEVEL JET/MOISTURE TRANSPORT SIGNAL. FAIRLY IMPRESSIVE LOW LEVEL BAROCLINIC ZONE DEVELOPS WITH TIME AND AS WOULD EXPECT FRONTOGENETICAL FIELDS SHOW THIS. KEPT THUNDER OUT OF FORECAST RIGHT NOW...BUT THIS MAY NEED TO BE INCLUDED IF ADVECTION SIGNAL STRENGTHENS ANY. FCST SOUNDINGS SHOWING LITTLE TO NO INSTABILITY /LAPSE RATES VERY UNIMPRESSIVE/...BUT PROXIMITY TO ELEVATED INSTABILITY NOT TOO FAR OFF. THIS BAND OF RAIN WILL LIKELY SLOW AS IT MOVES INTO NRN PORTIONS OF FORECAST AREA ON SUNDAY AS UPPER LOW MOVES OUT INTO CNTL PLAINS AND ENERGY FROM NRN STREAM BEGINS TO DIG DOWN BACKSIDE OF TROUGH. SHOULD ALL GO INTO MAKING RATHER IMPRESSIVE DEFORMATION BAND OF PRECIPITATION WHICH WILL AFFECT MOST OF AREA INTO SUNDAY NIGHT. GIVEN STRONG...CONSISTENT SIGNAL IN MODELS/ENSEMBLES...INCREASED RAIN PROBABILITIES SATURDAY NIGHT THROUGH SUNDAY NIGHT. COULD SEE SOAKING 1+ INCH RAINS...EVEN APPROACHING 2 INCHES SOME SPOTS GIVEN LONG DURATION/FAVORABLE DYNAMICS/THERMODYNAMICS AT PLAY HERE. .LONG TERM...MONDAY THROUGH THURSDAY BECOMING INCREASINGLY CONFIDENT THAT COMING WEEK INTO NEXT WEEKEND TO BE VERY ACTIVE/WET...BOTH IN TERMS OF DEPARTURE OF WEEKEND SYSTEM MENTIONED ABOVE...AND MORE STRONG ENERGY/WRN CONUS TROUGHS TO AFFECT THE AREA THROUGH THE WEEK. STRONG DOWNSTREAM RIDGING FROM PERSISTENT CORE OF NEGATIVE ANOMALIES IN GULF OF ALASKA...SHOULD ALLOW ENERGY FROM THE NRN STREAM TO SLIDE DOWN THE BACKSIDE OF THE RIDGE AND INTERACT WITH THE STRONG CNTL ROCKIES TROUGH BY MONDAY...WHICH WILL ALLOW FOR A LONGER DURATION PRECIPITATION CHANCE AS UPPER LEVEL LOW REDEVELOPS AND CLOSES OFF AGAIN AND LINGERS OVER THE WRN GREAT LAKES THROUGH TUESDAY. DETAILS UNCERTAIN RESOLVING SHORTWAVE ENERGY WHICH DETERMINES WHEN/WHERE THE INTERACTIONS TAKE PLACE...BUT FELT CONFIDENT ENOUGH PER LATEST SUITE OF DETERMINISTIC ECMWF/GFS/GEM RUNS...AND ENSEMBLE PROBABILITIES TO RAISE RAIN CHANCES MONDAY AND MONDAY NIGHT...AND THIS VERY WELL MAY NEED TO BE LINGERED INTO TUES WITH INCREASING RAIN CHANCES. NO REST FOR THE WEARY COMING OUT OF THIS SYSTEM AS GFS/ECWMF/ENSEMBLE MEANS ALL INDICATE ACTIVE SRN STREAM OUT OF MEAN WRN CONUS TROUGH TO CONTINUE TO SEND MOISTURE LADEN SYSTEMS WITH ACCESS TO GULF MOISTURE INTO THE MEAN LONGWAVE RIDGE OVER THE CNTL CONUS WITH SLOW MOVING /CLOSED/ UPPER LOWS WITH STRONG COMPONENTS OF BOTH WARM ADVECTIVE PRECIPITATION AND MATURE DEFORMATION ZONES. DETAILS STILL NOT CLEAR...BUT AT SOME POINT IN NEXT FEW DAYS MAY NEED TO ENTERTAIN NOTION OF HYDROLOGIC OUTLOOK FOR POTENTIAL HEAVY RAINS. && .AVIATION...TODAY AND TONIGHT WEAK SHORTWAVE ACROSS WESTERN MN/IA EARLY THIS MORNING RESPONSIBLE FOR A FEW SPRINKLES/-SHRA ACROSS EASTERN MN. THIS FEATURE WILL TRANSLATE EAST OF THE TAF SITES BY 12Z...TAKING ANY THREAT OF -SHRA WITH IT. MODEL SOUNDINGS AND TIME-HGT X-SECTIONS CONTINUE TO INDICATE PLENTY OF MOISTURE TRAPPED IN AND BELOW THE INVERSION IN THE 850- 700MB LAYER BEHIND THIS SHORTWAVE. THIS DEPICTED WELL BY SFC OBS AND SATELLITE IMAGERY EARLY THIS MORNING AS BROAD AREA OF VFR CLOUDS WEST AND NORTHWEST OF THE TAF SITES. THIS MOISTURE/CLOUDS TO SPREAD ACROSS THE TAF SITES TODAY/TONIGHT...WITH BKN-OVC CIGS IN 6K-8K FT RANGE TODAY GIVING WAY TO BKN LCL SCT CLOUDS IN THE 4K-6K FT RANGE TONIGHT. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM...BINAU AVIATION...RRS wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DES MOINES IA 348 AM CDT SUN OCT 14 2007 .SYNOPSIS... ROCKIES LG WV TROUGH NOW HAVING LARGE INFLUENCE ON MIDWEST WX. 110KT SPEED MAX ROUNDING BOTTOM WITH MATURE DEF ZN FROM LOW ACROSS SD/SRN MN. SUBTLE SHRT WVS TRAVERSING ACTIVE SWLY FLOW AIDING MCS WITH WIDESPREAD QG FORCING AND UVM OVER MUCH OF MO RIVER VALLEY. MORE SIGNIFICANT SHRT WV ALSO GETTING READY TO EJECT OUT OF TROUGH BASE. CONVECTION LINES UP FAIRLY WELL WITH H85/H7 THETA-E ADVECTION AND SW-NE FRONTOGENETICAL FORCING AXIS. MUCAPES AND NEGATIVE H7/H5 THETA-E LAPSE RATES PUSHING NEWD INTO IA ALONG WITH DEEP SHEAR GRADIENT SO STORMS MAY BEGIN PRODUCING HAIL MUCH LIKE TOWARD OMA. 07Z SFC ANLYS PLACES PARENT LOW OVER OK PANHANDLE WITH SECONDARY WV ALONG KS/NE BORDER. WRMFNT ALSO TRYING TO DEVELOP FROM NRN LOW ACROSS SRN MO WITH INVERTED TROUGH SHOWING ITS HAND INTO SIOUXLAND AREA. && .DISCUSSION... PRIMARY EFFORT OBVIOUSLY DEVOTED TO IMPENDING SIGNIFICANT RAIN EVENT. NOT A QUESTION OF IF...BUT WHERE. AFOREMENTIONED FORCING MECHANISMS WILL CONTINUE TO PUSH MCS ACROSS IA TODAY WITH REDEVELOPMENT EXPECTED AGAIN LATER TODAY. ALL 00Z MODELS OUTSIDE OF ECMWF NOW FAVORING MORE NLY SOLUTION. MODEL CONSENSUS WILL BE FAVORED THIS MORNING...BUT DO HAVE SOME RESERVATIONS. GFS DOES CONTAIN CONVECTIVE FEEDBACK AT TIMES BUT DOES NOT SEEM TO CONTAMINATE THE OVERALL FORECAST MUCH...AND ANYTIME THE NAM IS IN AGREEMENT IN THE LATER PERIODS RAISES SOME EYEBROWS. CONSENSUS HAS OLD SD/MN DEF ZN FADING OUT WITH ANOTHER CYCLE DEVELOPING LATER TODAY AS SHRT WV PULLS OUT OF TROUGH INTO MO VALLEY. DEF ZN AND STRONG BAND OF THETA-E ADVECTION AND FRONTOGENETICAL FORCING WILL SETUP SOMEWHERE FROM NRN NE INTO NWRN IA OR SRN MN. HAVE CONTINUED TRENDS OF PREVIOUS FORECAST WITH CATEGORICAL POPS IN MANY LOCATIONS TODAY AND NRN/WRN SECTIONS TONIGHT. MODELS HAVE BEEN EMPHATIC TO SUGGEST DRY SLOT PUNCHING INTO ERN IA SO HAVE REDUCED POPS SOMEWHAT E. LAST LOBE OF FORCING ROTATES AROUND LOW MON WITH CAT POPS LINGERING E...AND CHANCES STILL INTO TUE ALTHOUGH WORST SHOULD BE OVER BY THAT TIME. NEXT SYS SHOULD COME ONSHORE LATE MON AND REACH MIDWEST QUICKLY ON HEELS OF THIS SYS WED. GFS/ECMWF BOTH SUGGEST PCPN REACHING WRN SECTIONS WED AND ENTIRE FCST AREA WED NIGHT SO HAVE RAISED POPS ACCORDINGLY BUT NO CHANGES BEYOND THAT. MAY SEE QUITE A TEMP SPREAD TODAY NEARLY 20 DEGREES FROM NW-SE AS WRMFNT TRIES TO CROSS MO BORDER. THUS RESULTED IN AT OR BELOW COOLEST GUIDANCE NW...AND AT OR ABOVE WARMEST SE. BUFR SOUNDINGS DO NOT SUGGEST MUCH WARMING POTENTIAL MON SO TOWARD OR BELOW COOLEST GUIDANCE. THIS SEEMS TO BE ESPECIALLY TRUE TUE SO UNDERCUT COOLER NAM MOS BY A CATEGORY IN SEVERAL LOCATIONS. GENERALLY FOLLOWED A BLEND FOR MINS. && .HYDROLOGY... HYDRO CONCERNS STILL AN ISSUE WITH FLOOD WATCH BEING CONSIDERED. QUESTION WAS WHERE. WAS HOPING 03Z SREF WOULD PROVIDE SOME CONFIDENCE...BUT IT HAS NOT SUGGESTING HIGHEST AMOUNTS TO OUR NORTH. 00Z NAM/GFS/GEFS PAINTED NWRN IA IN THREAT WHILE WHAT APPEARS TO BE OUTLIER BUT TYPICALLY RELIABLE ECMWF FARTHER SOUTH. QPF GRIDS REFLECT 2-4 INCHES NW WHICH IS IN LINE WITH MODEL CONSENSUS...AND QUICK LOOK AT 06Z NAM NOW EVEN SHOWS 5+ INCH AMOUNTS BY MON EVE NRN PORTIONS...HOWEVER 06Z GFS SUGGESTS 2-3 INCH MAX NOW TOWARD SIOUXLAND AREA. WITH HIGH CONFIDENCE IN HEAVY RAIN BUT STILL UNSURE ON EXACT LOCATION TO TARGET WILL HOLD OFF ON WATCH BUT CERTAINLY MONITOR CLOSELY AND CONTINUE TO HIT HARD IN HWO. && .AVIATION...14/06Z LOW LEVEL JET CONTINUES TO INCREASE ACROSS NE AND KS THIS EVENING. RUC MODEL AND GFS SHOWING TREMENDOUS LIFT ALONG THE 850 MB BOUNDARY CUTTING ACROSS CENTRAL TO NORTHEAST IA TNT. STORMS BLOSSOMING IN NE WILL BE TIED TO BOUNDARY AND AREAL COVERAGE WILL CONTINUE TO INCREASE EASTWARD INTO THE STATE WITH TIME. CONSEQUENTLY...CIGS WILL LOWER OR REMAIN IN IFR CAT FOR MUCH OF NORTH THROUGH MON AFTERNOON AS CONVECTION GIVES WAY TO STRATIFORM STEADY RAINFALL IN MORE STABLE AIRMASS TO THE NORTHEAST. VSBYS ALSO EXPECTED TO CRASH AND REMAIN IN THE IFR CATEGORY FOR A GOOD PORTION OF THE PERIOD. OVER THE SOUTH...AS BOUNDARY LIFTS BKN MVFR CIGS SHOULD DEVELOP FOR THE PM HOURS NEAR KDSM AND KOTM. PSBL THUNDER LATER IN THE AFTERNOON AS AIRMASS DESTABILIZES WL CONTINUE INTO THE EVENING. VCTS COVERS BEST THERE. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ BSS/MJA/REV ia AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 1145 PM CDT SAT OCT 13 2007 .UPDATED AVIATION DISCUSSION FOR 14/06Z. .SYNOPSIS... LONG WAVE TROF REMAINS ACROSS THE WESTERN UNITED STATES WITH DEEPENING SFC LOW IN SE COLORADO. AMPLE MOISTURE IS BEING DRAWN NORTHWARD AHEAD OF THE SYSTEM IN STRENGTHENING SOUTHERLY FLOW AND HAVE SEEN NUMEROUS SHOWERS AND THUNDERSTORMS NEAR SFC BOUNDARY IN N KS AND MO. OTHERWISE...LOW CLDS AND SOME PATCHY MIST REMAINS ACRS MUCH OF CENTRAL IA IN EASTERLY SFC FLOW. && .DISCUSSION... MODELS CONTINUE TO ADVERTISE SLOW EVOLUTION OF WESTERN TROF AS IT EJECTS INTO THE PLAINS. MOISTURE WL REMAIN PLENTIFUL AS DEEP SOUTHERLY FLOW PERSIST THROUGH MONDAY AS SFC LOW SLOWLY DRIFTS FROM SOUTHEAST COLORADO TOWARD IA. ISENTROPIC LIFT IS FORECAST TO INCREASE TONIGHT AND SPREAD NORTHWARD AND SFC WARM FRONT PUSHES INTO THE STATE. EXPECT TO SEE EXPANDING PCPN INTO THE STATE THIS EVENING AS LLJ FOCUSES INTO THE STATE WITH STRONG THETA-E ADVECTION. WL KEEP CATEGORICAL POPS FOR MUCH OF THE CWA WITH CONTINUED FORCING ALLOWING PCPN TO KEEP GOING. FRONT WL BOG DOWN ACRS CNTRL/SOUTHERN IA ON SUNDAY AND REMAIN IN PLACE THROUGH MUCH OF MONDAY AS SFC LOW TRACKS ALONG THE BOUNDARY. THIS WL PROVIDE THE FOCUS FOR CONTINUED REDEVELOPMENT OF SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THIS TIMEFRAME. CATEGORICAL POPS WL REMAIN IN PLACE DURING THIS TIME AS ISENTROPIC LIFT AND QG FORCING PROVIDE A FAVORABLE ENVIRONMENT FOR ADDITIONAL RAINFALL. UPPER LOW WL BE SLOW TO MOVE INTO EARLY NEXT WEEK AS UPPER RIDGING SLIDES ACROSS THE TOP OF THE LOW IN A REX BLOCK FORMATION. LINGERING THREAT OF PCPN WL CONTINUE INTO TUESDAY AS STACKED SYSTEM DRIFTS NORTHEAST ACRS THE STATE. WL HAVE ONLY SHORT BREAK AS STRONG PAC JET PUSHES NEXT IN SERIES OF SHORTWAVES INTO THE MID SECTION TOWARD THE LATER HALF OF THE WORK WEEK. STILL HAVE SOME UNCERTAINTY AS TO TIMING OF SYSTEM AND EXTENT OF DEEPENING...BUT STILL APPEARS WEDNESDAY NIGHT THROUGH FRIDAY TIMEFRAME FOR LARGEST IMPACT. HAVE CONTINUED THREAT OF PCPN DURING THIS TIME AS TEMPERATURES REMAIN SEASONABLE. && .HYDROLOGY... ESF WILL REMAIN AS THREAT FOR LONG DURATION RAIN EVENT PERSISTS. SLOW MOVING SYSTEM WITH AMPLE MOISTURE WL PRODUCE DECENT RAINFALL THROUGH MONDAY NIGHT/TUESDAY TIMEFRAME. QPF REMAINS FROM ONE AND A HALF TO TWO AND A HALF INCHES WITH ISOLATED HIGHER AMOUNTS STILL POSSIBLE. FOCUS WL REMAIN ACRS THE NORTHERN HALF OF THE CWA AS WELL AS THE MISSOURI WATERSHED IN OUR SOUTHWEST CWA. PWATS TO REMAIN UNSEASONABLY HIGH FROM 1.25-1.5 INCHES WITH HIGH PCPN EFFICIENCY WITH DEEP SATURATED ATMOSPHERE WHICH IS RELATIVELY WARM FOR THIS TIME OF YEAR. EMBEDDED AREAS OF CONVECTION WL ALSO ADD TO THREAT OF ISOLATED HIGH AMOUNTS. FLOOD WATCH MAY LIKELY BE NEEDED IF CONFIDENCE CONTINUES TO GROW. && .AVIATION...14/06Z LOW LEVEL JET CONTINUES TO INCREASE ACROSS NE AND KS THIS EVENING. RUC MODEL AND GFS SHOWING TREMENDOUS LIFT ALONG THE 850 MB BOUNDARY CUTTING ACROSS CENTRAL TO NORTHEAST IA TNT. STORMS BLOSSOMING IN NE WILL BE TIED TO BOUNDARY AND AREAL COVERAGE WILL CONTINUE TO INCREASE EASTWARD INTO THE STATE WITH TIME. CONSEQUENTLY...CIGS WILL LOWER OR REMAIN IN IFR CAT FOR MUCH OF NORTH THROUGH MON AFTERNOON AS CONVECTION GIVES WAY TO STRATIFORM STEADY RAINFALL IN MORE STABLE AIRMASS TO THE NORTHEAST. VSBYS ALSO EXPECTED TO CRASH AND REMAIN IN THE IFR CATEGORY FOR A GOOD PORTION OF THE PERIOD. OVER THE SOUTH...AS BOUNDARY LIFTS BKN MVFR CIGS SHOULD DEVELOP FOR THE PM HOURS NEAR KDSM AND KOTM. PSBL THUNDER LATER IN THE AFTERNOON AS AIRMASS DESTABILIZES WL CONTINUE INTO THE EVENING. VCTS COVERS BEST THERE. /REV && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AVIATION/SHORT TERM...DONAVON/REV LONG...COGIL ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 338 AM CDT SUN OCT 14 2007 .DISCUSSION... DAYS 1-2... FORECAST CHALLENGE WILL BE THUNDERSTORMS TODAY AND THIS EVENING ALONG WITH TEMPERATURES THROUGH THE PERIOD. THIS EVENINGS UA ANALYSIS SHOWED THE CENTER OF THE 500 MB LOW JUST NORTH OF KGJT WITH A STRONG FETCH OF UPPER LEVEL WINDS EXTENDING FROM THE BASE OF THE LOW OVER SRN ARIZONA INTO THE CENTRAL HIGH PLAINS. A WEAK SHORTWAVE HAD LIFTED OUT OF NEW MEXICO AND HAD HELPED ORGANIZE AN AREA OF WIDELY SCATTERED THUNDERSTORMS ACROSS THE REGION. A STRONGER SHORTWAVE WAS SOUTH OF THE UPPER LOW OVER ARIZONA. SOME MID LEVEL COOLING HAD ALSO SPREAD INTO WESTERN KANSAS WITH 700 MB TEMPS COOLING TO +8C OVER KDDC. IN THE LOWER LEVELS, A SURFACE LOW WAS LOCATED IN THE OKLAHOMA PANHANDLE. A COLD FRONT BISECTED SOUTHWEST KANSAS FROM THE NORTHEAST TO SOUTHWEST AND CONTINUED DOWN INTO THE NORTHWEST TEXAS PANHANDLE. STRATUS HAD DEVELOPED SOUTH ACROSS THE WESTERN QUARTER OF THE CWA BEHIND THE FRONT. THE 00Z NAM AS WELL AS THE RUC HAVE A PRETTY DECENT HANDLE ON THE POSITION OF THE FRONT AND GRADUALLY MOVE IT EAST DURING THE DAY. BY EARLY AFTERNOON THE FRONT SHOULD BE JUST TO THE EAST OF KDDC. LOW CLOUDS COULD HANG ON FOR MOST OF THE DAY OVER THE WESTERN CWA BEHIND THE FRONT WITH TEMPERATURES NOT RISING A LOT OVER WHAT THEY ARE EARLY THIS MORNING. AREAS FROM KHYS THROUGH KDDC COULD SEE HIGHS TOPPING OUT AROUND MIDDAY WITH FALLING TEMPERATURES THIS AFTERNOON. STILL LOOKS LIKE A GOOD CHANCE FOR THUNDERSTORMS ALONG AND AHEAD OF THE FRONT THIS AFTERNOON. SURFACE DEWPOINTS ARE STILL NOT ALL THAT IMPRESSIVE ACROSS OKLAHOMA AD WEST TEXAS BUT FARTHER SOUTH A TONGUE OF 60+ DEWPOINTS WERE MOVING NORTH INTO CENTRAL TEXAS. THE NAM AND GFS INDICATE THAT THIS TONGUE OF MOISTURE WILL MOVE UP INTO SOUTH CENTRAL KANSAS BY THIS AFTERNOON. SHOULD BE ENOUGH INSTABILITY FOR A FEW SEVERE STORMS ONCE THEY GET GOING. THUNDERSTORMS COULD LINGER OVER THE EASTERN CWA THIS EVENING BEFORE MOVING OUT WITH THE FRONT. AS THE UPPER LOW CONTINUES EAST, SOME WRAPAROUND PRECIPITATION COULD SPREAD EAST ACROSS NORTHERN KANSAS TONIGHT AND CONTINUE INTO MONDAY. IT APPEARS THAT THE BEST CHANCES WILL BE NORTH OF THE CWA BUT CANT TOTALLY RULE OUT SOME OF IT SPREADING INTO THE CWA SO WILL KEEP SLIGHT CHANCE POPS GOING UP THERE. DAYS 3-7... TUESDAY MORNING WILL BE FAIRLY COOL AS SURFACE HIGH PRESSURE SETTLES OVER WESTERN KS. A SURFACE FRONT WILL STALL ACROSS SOUTHERN OK/NORTH TX TUESDAY. RICH GULF MOISTURE WILL BE IN PLACE SOUTH OF THIS BOUNDARY. A STRONG SHORTWAVE TROUGH WILL APPROACH SW KS TUESDAY NIGHT, AND THEN MOVE ACROSS THE AREA WEDNESDAY. MID TO UPPER LEVEL TEMPS WILL BE FAIRLY COLD WITH THIS SYSTEM. THE 00Z SUITE OF MODELS ARE ALL COMING IN LINE WITH A FAIRLY ROBUST SYSTEM, ESPECIALLY THE CANADIAN AND UKMET AND EVEN THE ECMWF. GIVEN THE STRONG DYNAMICS AND RICH MOISTURE, THUNDERSTORMS MAY DEVELOP AS EARLY AS 6-12 UTC WEDNESDAY, AND THEN MOVE ACROSS THE REMAINDER OF THE FCST AREA WEDNESDAY. ONE THING THAT COULD LIMIT THUNDERSTORMS HERE ON THE HIGH PLAINS IS THE CAPPING INVERSION. BUT GIVEN THE FAIRLY COOL TEMPS ALOFT WITH THIS SYSTEM, THIS SHOULD NOT BE A BIG PROBLEM. SOME OF THESE STORMS COULD BE SEVERE, ESPECIALLY IN OUR EASTERN COUNTIES WEDNESDAY AFTERNOON. POPS WERE RAISED FOR THIS TIME PERIOD, ESPECIALLY IN OUR EASTERN COUNTIES WHERE THE MOISTURE WILL BE DEEPER. ANOTHER STRONG SHORTWAVE TROUGH WILL APPROACH BY SATURDAY OR SUNDAY. HOWEVER, THIS SYSTEM WILL PROBABLY BE FURTHER NORTH AND THE MOIST AXIS MAY BE FURTHER EAST. PRECIP CHANCES DO NOT LOOK VERY GOOD AFTER WEDNESDAY. && .AVIATION... STRATUS WILL LINGER ALL DAY TODAY AND INTO TONIGHT AT GCK. STRATUS WILL DEVELOP AT DDC/HYS DURING THE MORNING OR EARLY AFTERNOON AS COLD ADVECTION DEVELOPS. CEILINGS WILL BE BETWEEN 1000 AND 2000 FT, WITH THE LOWEST CEILINGS AT GCK. VSBYS MAY DROP TO 3 TO 5 MILES AT TIMES, ESPECIALLY AT GCK. MOST OF THE THUNDERSTORM ACTIVITY WILL STAY EAST OF THE AVIATION SITES. A FEW LIGHT SHOWERS ARE POSSIBLE ANY TIME TODAY. && .PRELIMINARY POINT TEMPS/POPS... DDC 74 48 63 42 / 30 30 0 0 GCK 61 44 63 41 / 30 10 0 0 EHA 64 44 64 42 / 20 0 0 0 LBL 64 45 65 42 / 20 0 0 0 HYS 70 49 61 42 / 50 60 20 0 P28 80 52 66 46 / 60 60 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN02/24 ks AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 250 AM EDT SUN OCT 14 2007 .SHORT TERM.../THE REST OF TONIGHT/ MID AND HIGH CLOUDS WERE INCREASING ACROSS EASTERN KENTUCKY. THE LATEST RUC SHOWS MID LEVEL MOISTURE INCREASING AND LINGERING THROUGH THE NIGHT...ESPECIALLY IN THE NORTHERN PORTION OF OUR CWA. INCREASED CLOUD COVER TO GO WITH MOSTLY CLOUDY SKIES IN THIS AREA. MODELS ALSO SHOW A WEAKENING H5 WAVE MOVING THROUGH OVERNIGHT. NOT EXPECTING THIS TO PRODUCE ANY PRECIP THOUGH. ALSO INCREASED SKY COVER AMOUNTS ELSEWHERE TO GO WITH A PARTLY CLOUDY FORECAST. DID NOT CHANGE TEMPERATURES MUCH...EVEN WITH INCREASED CLOUD COVER. ATTM...MOSTLY CLEAR SKIES HAVE ALLOWED VALLEY TEMPERATURES TO BEGIN TO PLUNGE. AS THE CLOUDS MOVE IN...THIS SHOULD SLOW THE TEMPERATURE DROP...HOWEVER THE PREVIOUS FORECAST LOWS SHOULD BE ABLE TO BE REACHED WITH THE HELP OF THE INITIAL TEMPERATURE DROP. ONLY MADE SOME MINOR TWEAKS TO TEMPERATURES OVERNIGHT. UPDATED TEXT...DIGITAL AND GRAPHICAL PRODUCTS WILL BE OUT SOON. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TONIGHT THROUGH SUNDAY NIGHT/ HIGH PRESSURE OVER THE OHIO VALLEY WILL SLIDE EAST ON SUNDAY...WITH UPPER RIDGING BUILDING INTO OUR AREA. THE CHALLENGE IN THE SHORT TERM IS THE AMOUNT OF CLOUDINESS TONIGHT AND EFFECT ON OVERNIGHT LOW TEMPERATURES. MODEL TIME HEIGHTS INDICATE AN INCREASE IN HIGH LEVEL CLOUD...CI/CS ACROSS THE AREA TONIGHT...AND ALSO SOME MID LEVEL CLOUD ESPECIALLY IN THE NORTH. SATELLITE TRENDS SHOW CLOUD STREAMING EAST FROM AREA OF CONVECTION OVER MISSOURI...BUT ALSO SHOW CLOUD ERODING AS IT MOVES EAST. VARIOUS MOS GUIDANCE SHOWING DIFFERENCES IN SKY COVER WITH OLD FWC SHOWING OVC AT JKL...LOZ AND 5I3 BY 12Z SUNDAY. HOWEVER THIS IS OUTLIER WITH OTHER GUIDANCE SHOWING SCT TO CLEAR. BASED ON CURRENT TRENDS....AND GFS AND WRF MODEL GUIDANCE HAVE FOLLOWED IDEA OF SOME INCREASE IN CLOUDS TONIGHT. BUT ALSO EXPECT CLOUDS TO REMAIN MAINLY SCATTERED AT BEST...ALTHOUGH SOME BKN BUT THIN CS/CI MAY OCCUR. WITH SKIES BEGINNING AS CLEAR THIS EVENING...DEWPOINTS MAINLY IN THE LOWER 40S TO UPPER 30S...AND MAINLY HIGH CLOUDS TONIGHT...EXPECT ABOUT A 10 DEGREE RIDGE VALLEY TEMPERATURE SPLIT TO DEVELOP. THE SLIGHT INCREASE IN CLOUDS TONIGHT SHOULD PREVENT TEMPERATURES FROM GETTING AS COLD AS THIS MORNING. WE HAD A COUPLE OF COOP REPORTS OF 32 THIS MORNING AND A 31 FROM A WEATHER SPOTTER. EXPECT COLDEST READINGS TO BE IN THE UPPER 30S OVERNIGHT...BUT THERMAL BELT RIDGES IN THE UPPER 40S. THE MAVMOS SEEMS TO BE HANDLING THIS TEMPERATURE SPLIT THE BEST...AND HAVE FOLLOWED CLOSELY FOR OVERNIGHT LOWS. ON SUNDAY WARM AIR ADVECTION CONTINUES AND LOOK FOR HIGH TEMPERATURES TO BE IN THE 70S. MAVMOS LOOKS A LITTLE TOO HIGH IN THE EAST BASED ON ITS PERFORMANCE TODAY...BUT SHOULD BE GOOD IN THE SOUTHWEST PART OF THE FORECAST AREA. WARM UP CONTINUES WITH LOWS SUNDAY NIGHT SEVERAL DEGREES WARMER THAN THOSE EXPECTED TONIGHT. .LONG TERM.../MONDAY THROUGH SATURDAY/ ALL MODEL SOLUTIONS DIFFER GREATLY IN THEIR HANDLING OF NEXT WEEKS WEATHER. DGEX AND GFS ARE MUCH SLOWER AND NOT NEARLY AS WET AS ECMWF RUN. BOTH GFS AND DGEX FORM A VERY STRONG AREA OF LOW PRESSURE IN THE CENTRAL PLAINS FOR NEXT SATURDAY NIGHT AND SUNDAY IN THE 6Z RUN. THE GFS BACKED OFF ON THIS FEATURE IN THE 12Z RUN DRAMATICALLY. WITH SO MUCH UNCERTAINTY IN THE MODELS IN REGARDS TO WEATHER FOR THE END OF NEXT WEEK...WENT PRIMARILY WITH THE GFS SOLUTION...WITH SOME TWEAKS MADE BASED ON THE 6Z DGEX SOLUTION. INCREASED PRECIP CHANCES OVERALL FOR NEXT THURSDAY AND FRIDAY. KEPT PRECIP OUT OF THE FORECAST FOR NOW NEXT SATURDAY CONSIDERING THE DRASTIC DIFFERENCES AMONGST THE DIFFERENT MODELS. CONTINUED TREND OF COOLER THAN MEXMOS DAYTIME HIGH TEMPERATURES...TAKING INTO ACCOUNT THE AMOUNT OF CLOUD COVER ANTICIPATED WED-SAT OF NEXT WEEK AND THE INCREASED CHANCES OF PRECIPITATION. WINDS WERE TWEAKED SLIGHTLY TO REFLECT CHANGES MADE TO FRONTAL PASSAGES NEXT WEEK. SKY COVER FORECAST WAS QUITE A CHALLENGE WITH THE MODELS ALL COMING WITH VERY DIFFERENT SOLUTIONS...SO WENT WITH PARTLY TO MOSTLY CLOUDY SKIES EACH DAY NEXT WEEK...WITH THE BEST COVERAGE OF LOW AND MIDDLE CLOUDS FORECAST FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT AS AN AREA OF LOW PRESSURE MOVES OUT OF THE PLAINS. DEWPOINTS WERE ALREADY IN GOOD SHAPE AND ONLY SMALL CHANGES WERE MADE THERE. KEPT IN MENTION OF THUNDERSTORMS FOR TUESDAY AFTERNOON AND EVENING...AS IT APPEARS THERE WILL BE JUST ENOUGH INSTABILITY PRESENT TO PERHAPS SPARK AN ISOLATED STORM OR TWO. GFS ALSO SHOWING A PERSISTENT AND FAIRLY STRONG 850 HPA JET DURING THE DAY TUESDAY...THIS FEATURE HAS BEEN CONSISTENT IN THE MODEL DATA FOR 3 DAYS NOW...WHICH IS SUPPORTED BY 70-80KT UPPER LEVEL JET CORES. THESE UPPER LEVEL DIVERGENCE ASSOCIATED WITH THESE JET FEATURES WILL ALSO LEND SUPPORT TO ISOLATED THUNDERSTORMS ON TUESDAY BY INCREASING UPWARD VERTICAL MOTION IN THE LOW AND MIDDLE LEVELS OF THE ATMOSPHERE. WENT WITH FAIRLY LIGHT RAINFALL AMOUNTS ACROSS THE BOARD...WITH THE BEST AREAL COVERAGE ON TUESDAY AND WEDNESDAY. SOME LINGERING SHOWERS WILL BE POSSIBLE WEDNESDAY AND THURSDAY IN MOIST NORTHWEST FLOW...IN THE HIGHER TERRAIN ALONG THE VIRGINIA AND WEST VIRGINIA BORDERS...SO A CHANCE OF RAIN WAS INCLUDED IN THE FORECAST FOR THOSE TWO DAYS AS WELL. && .AVIATION.../06Z TO 06Z/...UPDATED VFR CONDITIONS WILL PREVAIL THROUGH THE TAF PERIOD. A THINNING AND SCATTERING DECK OF MID LEVEL CLOUDS WILL CROSS THE SKY DURING THE REMAINDER OF THE NIGHT BEFORE COMPLETELY SCATTERING OUT BY MIDDAY SUNDAY. THESE CLOUDS WILL KEEP BR FORMATION TO A MINIMUM AND NOT WORTH CARRYING IN THE TAFS. WINDS THROUGH THE PERIOD WILL BE LIGHT...GENERALLY FROM THE EAST WHEN THERE IS A DIRECTION. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...SBH/WJM LONG TERM....AR AVIATION...GREIF ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 420 AM EDT SAT OCT 13 2007 .DISCUSSION... 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW UPR LO OVER SE CANADA FINALLY EDGING EWD AND GIVING WAY TO SHRTWV RDGING OVER THE UPR GRT LKS. AXIS OF SFC HI PRES UNDER THIS RDG STRETCHING FM NW ONTARIO INTO WI IS BRINGING A MOCLR AND CHILLY NGT TO THE FA AS 00Z TAMDAR SDNG FM SAW SHOWS A DRY STABLE AIRMASS IN PLACE. TWO SHRTWVS OF INTEREST TO THE W. THE MOST IMPRESSIVE IS ROUNDING THE BASE OF SRN BRANCH UPR TROF OVER THE SW CONUS. CLDS/SHRA IN THE WAD PATTERN WELL IN ADVANCE OF THIS TROF/SHRTWV ARE AS CLOSE AS SW MN. ANOTHER MORE MSTR DEPRIVED SHRTWV EMBEDDED IN MORE SUBTLE NRN BRANCH FLOW NR THE US/CNDN BORDER IS MOVING THRU SRN SASKATCHEWAN. MAIN FCST CONCERNS THIS PACKAGE ARE TEMPS TDAY THEN PCPN CHCS TNGT INTO MID WEEK. FOR TDAY...SHRTWV RDGING/SFC HI PRES/DRY AIRMASS PROGGED TO DOMINATE THE FA. ALTHOUGH SOME MID/HI CLDS WL SPILL INTO THE FA FM THE W-S TDAY WELL IN ADVANCE OF TROFFING MOVING INTO THE CNTRL PLAINS...THE DAY WL BE DRY. MIXING TO H825-85 ON NAM/GFS FCST SDNGS YIELDS HI TEMPS TOPPING OUT IN THE MID 50S. THE FCST FOR TNGT WL DEPEND ON INTERACTION BTWN NRN BRANCH SHRTWV RIPPLING TOWARD NW LK SUP BY 12Z MON AND UPR TROF IN THE PLAINS AND ITS ASSOCIATED WARM CONVEYOR BELT MSTR SHIELD STREAMING NEWD TOWARD THE CWA. THE 00Z GFS/UKMET SEEM THE MOST CONSISTENT WITH THE FCST SCENARIO SHOWING A LESS-PHASED NRN BRANCH SHRTWV SHUNTING THE MAJORITY OF THE MSTR TO THE S...A RSNBL CONCLUSION GIVEN POSITIVE TILT OF THE UPR TROF IN THE PLAINS. IN FACT...NCEP PREFERS THE GFS/UKMET. GIVEN DRY ANTECEDENT AIRMASS... EXPECT A SHARP NRN EDGE TO PCPN SHIELD. GFS FCST SDNGS/SHARPEST H6-8 FGEN SUGS BULK OF PCPN WL STAY TO THE S AND IMPACT MAINLY ONLY SRN MNM COUNTY. GOING PCPN FCST RESTRICTING POPS TO THE SRN TIER SEEMS IN LINE WITH GFS FCST DYNAMICS/MSTR. THE ONLY CHG MADE WAS TO BUMP POP UP TO 50 ARND MNM TO MESH BETTER WITH GRB FCST. ALTHOUGH GFS MOS SHOWS POP ARND 30 AS FAR N AS IWD-MQT-ERY...MODEL FCST SDNGS SHOW A PROHIBITIVELY DEEP DRY LYR THERE FOR ANY CHC OF RA N OF IMT-ISQ OR SO. AS FOR TEMPS...TRENDED A BIT LOWER THAN PREVIOUS FCST EXCEPT OVER THE FAR S WITH EXPECTATION THIS DRY AIR WL ALLOW SGNFT RADIATIONAL HEAT LOSS IN LGT WIND REGIME DESPITE HI CLDS. GFS/UKMET SHOW DRY AIRMASS OVERSPREADING THE FA IN THE WAKE OF NRN BRANCH SHRTWV PASSAGE ON MON AS SFC HI PRES BLDS OVER ONTARIO UNDER BLDG UPR RDG IN SCNTRL CAN. ANY LINGERING RA OVER THE FAR S WL END EARLY IN THE DAY AS LLVL NE FLOW PUSHES DRY AIR INTO THE FA...BUT GFS FCST SDNGS HINT CLD COVER AT MNM MAY BE FAIRLY STUBBORN. BUT TO THE N...SKIES SHOULD BECOME MOSUNNY. GFS/UKMET SHOW DRY HI PRES REMAINING DOMINANT MON NGT...BUT BOTH MODELS HINT THAT SHRTWV MOVING NWD ON THE ERN FLANK OF CUTOFF IN THE PLAINS WL CAUSE THIS LARGER SCALE FEATURE TO WOBBLE TO THE N WITH INCRSG RH ALF. GFS EVEN GENERATES SOME PCPN OVER SRN MNM COUNTY BY 12Z TUE. HOWEVER...GFS FCSTS SHARPEST H6-8 FGEN/UPR DVGC TO STAY TO THE S. SINCE MODEL FCST SDNG FOR MNM AT 12Z TUE SHOWS A 100-150MB DEEP DRY LYR CENTERED ARND H75...WL GO DRY EVERYWHERE THE WHOLE NGT IN LGT WITH UKMET. TENDED BLO MOS GUIDANCE FOR MIN TEMPS OVER THE N WITH EXPECTATION OF TENACIOUS DRY AIR BUT NR GUIDANCE ACRS THE S WHERE DEEPER MSTR WL ARRIVE OVERNGT. GFS/UKMET BOTH SHOW MSTR CREEPING NWD ON TUE AS PLAINS TROF DRFITS SLOWLY NEWD. EXCEPT FOR A FEW MINOR ADJUSTMENTS...KEPT FLAVOR OF PREVIOUS FCST SHOWING GRDLY INCRSG POPS S-N. TENDED A TAD SLOWER THAN THE GFS AS UKMET AND ESPECIALLY THE NEW 00Z ECMWF TEND TO HOLD DRY AIR IN LONGER. BUMPED UP TEMPS/POPS AND ADDED PTCHY FOG ON TUE NGT TO REFLECT APRCH OF WARM FNT/ABUNDANT CLD COVER/INCRSG LLVL MSTR. NO OTHER CHGS MADE TO FCST. COORDINATED WITH APX/LOT/GRB. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... VFR CONDITIONS WILL PREVAIL AT BOTH TAF SITES OVER THE NEXT 24 HOURS AS SFC HIGH PRESSURE REMAINS IN PLACE. MAINLY HIGH CLOUDS ARE EXPECTED ACROSS UPPER MICHIGAN. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE FROM THE WESTERN GREAT LAKES SHIFTING INTO NORTHERN ONTARIO WILL CONTINUE TO REMAIN IN CONTROL OF THE WEATHER ACROSS LAKE SUPERIOR THROUGH TUESDAY. EAST WINDS WILL INCREASE UP TO 25 KNOTS FROM MONDAY INTO TUESDAY AS THE PRESSURE GRADIENT TIGHTENS BETWEEN THE ONTARIO HIGH AND LOW PRESSURE MOVING INTO THE MID MISSISSIPPI VALLEY. THE STRONGER WINDS WILL ALLOW WAVES TO BUILD INTO THE 4 TO 7 FOOT RANGE TUESDAY. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...KC MARINE...JLB AVIATION...JLB mi