Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 10/20/12


AREA FORECAST DISCUSSION
NWS LITTLE ROCK AR
107 AM CDT THU OCT 18 2012 .AVIATION...18/06Z TAF CYCLE CDFNT AND ASSOCD CONVECTION HAS PUSHED SE OF THE FA ATTM. VFR CONDS WL PREVAIL THRU THE PD. GUSTY W/NW WINDS WL INCRS BY MID TO LATE MRNG ACRS THE AREA...WITH GUSTS UP TO 25 KTS COMMON. WINDS WL DIMINISH DURG THE EARLY EVENING HRS. /44/ && .PREV DISCUSSION... /ISSUED 207 PM CDT WED OCT 17 2012/ SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT FIRST PERIOD WILL STAY WITH THE HIGH POPS WITH SEVERE STORM MENTION AS THE CONVECTION OVER EASTERN OK WITH WORK ITS WAY EAST WITH THE BOUNDARY. HAVE SEEN A PREFRONTAL TROUGH DEVELOP SOME CONVECTION AND THEN ADDITIONAL LINE ALONG AND WITH THE COLD FRONT. WRF AND RR MODELS DEPICT THIS SCENARIO. THE CONVECTION SHOULD MOVE ACROSS THE STATE FAIRLY QUICKLY WITH THE GOOD MID LEVEL WINDS AND REACH EASTERN AR AROUND 06Z TO 10Z. QPF WITH THIS SYSTEM IS A BIT UNCERTAIN DUE TO SPEED AND HOW MUCH MOISTURE WILL BE ADVECTED INTO THE CONVECTION. WENT WITH HIGHEST FROM A 1/4 TO 3/4 INCH WITH A FEW ISOLATED HIGHER SPOTS. SOME LOCATIONS WILL SEE ONLY SEE A FEW TENTHS. ON THURSDAY...THE SURFACE HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT AND BRING QUITE A DRY AND COOL AIR MASS. WINDS WILL BE ELEVATED ESPECIALLY OVER NORTHERN AR TO CENTRAL...AND WITH MINIMUM RH VALUES DROPPING INTO THE 20S...A FIRE WEATHER DANGER STATEMENT WILL BE NEED. SOIL MOISTURE LEVELS ARE ABOVE CRITICAL VALUES AT THIS TIME. DUE TO THE STRONG SURFACE AND UPPER SYSTEM...THE COOLER AIR MASS WILL HOLD OVER THE AREA THROUGH SATURDAY. ANY CLOUDS ON THURSDAY OVER NORTHERN AR WILL THIN INTO FRIDAY AND MOSTLY SUNNY SKIES WILL BE SEEN FRIDAY AND SATURDAY. TEMPS WILL BE AT OR BELOW THROUGH THE PERIOD THEN A WARMING TREND INTO NEXT WEEK. LONG TERM...SUNDAY THROUGH WEDNESDAY... A SOMEWHAT FLAT RIDGE WILL DEVELOP IN THE UPPER LEVEL FLOW ACROSS THE REGION DURING THE EXTENDED TERM. A FEW SHORTWAVES WILL LIKELY RIDE OVER THE RIDGE IN THE SWLY FLOW ALOFT. EXTENDED TERM MODELS ARE IN DISAGREEMENT OVER THE HANDLING OF A SHORTWAVE DURING THIS TIME FRAME...WITH THE GFS BEING MUCH WETTER AND GENERATING A WIDE AREA OF PRECIP ACROSS THE NWRN PART OF THE STATE...WITH A DRIER ECMWF AND A CANADIAN MODEL THAT IS SOMEWHAT IN BETWEEN. AT THIS TIME I AM LEANING MORE TOWARD THE ECMWF SOLUTION BUT I AM PUTTING SOME LOW POPS ACROSS THE NORTHERN/NWRN ZONES ON TUESDAY AND TUESDAY NIGHT PER THE CANADIAN MODEL. && .LZK WATCHES/WARNINGS/ADVISORIES...NONE. && $$
AREA FORECAST DISCUSSION
NWS TUCSON AZ
215 AM MST THU OCT 18 2012 .SYNOPSIS...A MODEST MOISTURE INCREASE WILL BRING SOME CLOUDS AND A FEW LIGHT SHOWERS TODAY...MAINLY SOUTH AND WEST OF TUCSON. OTHERWISE HIGH PRESSURE WILL CONTINUE TO BRING WARM TEMPERATURES TO THE AREA INTO THE COMING WEEKEND. AS HIGH PRESSURE WEAKENS OVER THE REGION EARLY NEXT WEEK...TEMPERATURES WILL FALL BACK TO NEAR SEASONAL AVERAGES. && .DISCUSSION...THE MOISTURE TREND CONTINUES THIS MORNING...WITH SURFACE DEWPTS UP 10 TO 20 DEGREES OVER THE PAST 24 HOURS...PUTTING MOST LOCATIONS FROM TUCSON SOUTHWARD INTO THE 40S AND 50S. BLENDED TOTAL PW ESTIMATES NOW IN THE 3/4 INCH RANGE WITH DEEPER VALUES JUST SOUTH OF THE INTERNATIONAL BORDER. THE CORE OF THE MOISTURE REMAINING WITH WHAT USED TO BE PAUL (NO LONGER EVEN A DEPRESSION) IS JUST WEST OF THE NORTHERN BAJA COAST. SOME WEAK MID LEVEL CLOUD ENHANCEMENT ON IR...WE`LL CONTINUE WITH OUR FORECAST OF A FEW LIGHT SHOWERS / SPRINKLES TODAY MAINLY SOUTH AND SOUTHWEST OF TUCSON EVEN AS THE LATEST HRRR RUNS KEEP MEASURABLE PRECIP JUST SOUTH OF THE BORDER (EMPHASIS ON THE "LIGHT" PART). THE NORTHERN AREA OF THE RIDGE AXIS WILL DAMPEN AND PHASE EASTWARD OVER THE NEXT 72 HOURS WITH REORIENTATION ASSOCIATED WITH AN ANCHOR FROM MEXICO INTO THE PLAINS AND MISSISSIPPI VALLEY LATE IN THE WEEKEND. AS THIS HAPPENS THE RAPIDLY FILLING REMNANT CIRCULATION OFF THE NORTHER BAJA COAST WILL KICK ACROSS THE AREA SUNDAY INTO MONDAY. NOT A LOT OF MOISTURE OR DYNAMICS ASSOCIATED WITH IT...BUT COULD AGAIN BRING A FEW LIGHT SHOWERS INTO THE PICTURE. PATTERN CHANGE BEGINS NEXT WEEK WITH A STRONG MEAN TROUGH POSITION BUILDING WITH BROAD BASED SUPPORT IN THE EASTERN PACIFIC AND WEST COAST. NOT SURE IF WE WILL SEE MUCH OF A SPLIT THIS FAR SOUTH YET...BUT IT SHOULD SERVE NICELY TO KNOCK TEMPERATURES BACK TO NEAR CLIMO NEXT WEEK ALONG WITH A FEW BREEZY AFTERNOONS. && .AVIATION...SCT-BKN CLOUDS AROUND 5-9K FT AGL MAINLY SOUTH TO SOUTHWEST OF KTUS THRU TONIGHT OR 19/09Z. SLIGHT CHANCE OF -SHRA UNTIL 19/01Z. SURFACE WIND GENERALLY LESS THAN 10 KTS WITH NORMAL DIURNAL TRENDS. AVIATION DISCUSSION NOT UPDATED FOR TAF AMENDMENTS. && .FIRE WEATHER...CONTINUED DRY AND UNSEASONABLY WARM FOR MOST OF THE AREA INTO THE WEEKEND. NORMAL DIURNAL WIND TRENDS. MOISTURE FROM THE TROPICS WILL BRING INCREASED CLOUDS AND PERHAPS A FEW LIGHT SHOWERS MAINLY SOUTH AND WEST OF TUCSON TODAY...ALONG WITH A BRIEF INCREASE IN RH VALUES. && .TWC WATCHES/WARNINGS/ADVISORIES...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/TUCSON
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1110 AM MDT THU OCT 18 2012 .AVIATION... DRY NORTHWESTERLY UPPER FLOW ALOFT WILL BE CONDUCIVE TO GUSTY WINDS AT TIMES...DRY CONDITIONS AND GENERALLY CLEAR SKIES AT THE KALS...KCOS AND KPUB TAF SITES THROUGH TONIGHT. && .PREV DISCUSSION... /ISSUED 402 AM MDT THU OCT 18 2012/ SHORT TERM... (TODAY AND TONIGHT) SO FAR TEMPS OVR THE SERN PLAINS HAVE NOT GONE BELOW FREEZING AND HAVE BEEN IN THE MID AND UPR 30S...BUT DEW POINTS REMAIN QUITE LOW AND THERE IS STILL TIME FOR TEMPS TO FALL BELOW FREEZING THIS MORNING. THUS WL LEAVE THE FREEZE WARNING IN EFFECT. MAIN CONCERN TODAY IS THE POTENTIAL FOR RED FLAG CONDITIONS. WITH A DRY AIR MASS IN PLACE OVR THE AREA...DEW POINTS TODAY WL BE QUITE LOW AND MIN RH VALUES ARE EXPECTED TO BE BELOW 15 PERCENT AT THE LOWER ELEVATIONS. BRISK DRY NW FLOW WL BE FOUND OVR THE AREA TODAY...ALTHOUGH GENERALLY NOT QUITE AS STRONG AS YESTERDAY IN MOST AREAS. THE STRONGEST GRADIENT WL BE OVR THE FAR SERN PLAINS...AND IT LOOKS LIKE GUSTS WL MEET RED FLAG CRITERIA THIS AFTERNOON OVR KIOWA COUNTY AND A GOOD PORTION OF PROWERS COUNTY...SO WL ISSUE RED FLAG WARNING. THE HRRR AND LOCAL WRF ARE SHOWING GUSTS ALSO MEETING CRITERIA OVR NRN EL PASO COUNTY...MAINLY EAST OF THE INTERSTATE SO WL ALSO ISSUE A WARNING FOR THIS AREA. THERE ARE TWO OTHER AREAS OF CONCERN...THE FAR EASTERN AREAS OF SRN EL PASO COUNTY (FIRE ZONE 227) AND THE NRN PORTIONS OF THE SAN LUIS VALLEY (FIRE ZONE 224)...WHERE GUSTS ARE ALSO EXPECTED TO REACH RED FLAG WARNING CRITERIA THIS AFTERNOON. THE PORTIONS OF THESE FIRE ZONES WHERE THE GUSTS WL PROBABLY MEET CRITERIA SEEM TOO LOCALIZED TO ISSUE RED FLAG WARNINGS FOR THE ENTIRE ZONE...SO WL NOT ISSUE A HIGHLIGHT AT THIS TIME. FOR TONIGHT...THE WEATHER WL REMAIN DRY WITH LITTLE IF ANY CLOUDS. SOME AREAS...MAINLY ALONG THE ARKANSAS RIVER VALLEY...MAY AGAIN SEE LOW TEMPS FALL BELOW 32 DEGREES. WL HAVE TO WAIT AN SEE IF WE GET A FREEZE THIS MORNING TO SEE IF A HIGHLIGHT MAY BE NEEDED TONIGHT. LONG TERM... (FRIDAY THROUGH WEDNESDAY) ..WARM AND DRY THROUGH THE WEEKEND... FRIDAY-SUNDAY...MODELS REMAIN IN GOOD AGREEMENT THROUGH THE WEEKEND AS MODERATING NORTHWEST FLOW ALOFT ACROSS THE REGION ON FRIDAY BECOMES MORE WEST TO SOUTHWEST SATURDAY AND INCREASES AGAIN ON SUNDAY WITH PAC NORTHWEST ENERGY DIGGING ACROSS THE GREAT BASIN AND NORTHERN TIER OF STATES. MODELS ALSO INDICATING THE WEAKENING REMNANTS OF POST TROPICAL SYSTEM PAUL LIFTING OUT ACROSS THE DESERT SOUTHWEST ON SUNDAY. WARMING ALOFT PROGGED ACROSS THE AREA FRIDAY AND SATURDAY ALONG WITH DOWNSLOPE FLOW WILL ALLOW FOR TEMPERATURES TO WARM BACK TO ABOVE SEASONAL AVERAGES...ESPECIALLY ON SATURDAY WITH HIGHS EXPECTED TO BE IN THE 70S AND 80S ACROSS THE EASTERN PLAINS WITH MAINLY 50S AND 60S ACROSS THE HIGHER TERRAIN. DEVELOPING DOWNSLOPE FLOW AND THE WARMING ALOFT WILL ALSO ALLOW FOR WARMER OVERNIGHT LOWS...ESPECIALLY OVER AND NEAR THE HIGHER TERRAIN. A WEAK NORTHERLY SURGE/COLD FRONT AND COOLING ALOFT AHEAD OF PAC NORTHWEST TROUGH WILL BRING ONLY SLIGHTLY COOLER TEMPERATURES ACROSS THE AREA ON SUNDAY. MONDAY-WEDNESDAY...LESSER CONFIDENCE FORECAST...ESPECIALLY FOR THE MIDDLE OF THE WEEK AND BEYOND...WITH MODELS DIFFERING ON AMPLITUDE AND MOVEMENT OF PACIFIC ENERGY DIGGING INTO THE GREAT BASIN AND ROCKIES. MODELS DO AGREE THAT THE REMNANTS OF THE TROPICAL SYSTEM TO REMAIN WELL SOUTH OF THE AREA AS IT CONTINUES TO WEAKEN AND LIFT OUT ACROSS SOUTHERN NEW MEXICO AND THE SOUTHERN HIGH PLAINS. THE LATEST GFS REMAINS THE DEEPEST SOLUTION WITH MODERATE AND MAINLY DRY SOUTHWEST FLOW ACROSS THE STATE THROUGH WEDNESDAY WITH A STAND UP PACIFIC COLD FRONT MOVING ACROSS THE STATE WEDNESDAY AND WEDNESDAY NIGHT. THE ECMWF IS FASTER AND LESS AMPLIFIED WITH THE SYSTEM AND MOVES THE FRONT ACROSS THE AREA MONDAY NIGHT AND TUESDAY WITH A SECONDARY SURGE OF COLD AIR MOVING ACROSS THE AREA WEDNESDAY NIGHT AND THURSDAY. AT ANY RATE...PATTERN WOULD SUGGEST BEST CHANCES OF PRECIP TO BE ACROSS THE HIGHER TERRAIN ALONG AND WEST OF THE CONTDVD WITH TEMPERATURES SLOWLY COOLING BACK TO AT OR BELOW SEASONAL AVERAGES BE THE MIDDLE OF THE WEEK. -MW AVIATION... WITH DRY NW FLOW IN PLACE...FEW IS ANY CLOUDS ARE EXPECTED TODAY AND TONIGHT AND THUS VFR CONDITIONS WL BE FOUND ACRS THE AREA. SOME AREAS WL SEE BREEZY NORTHWEST WINDS TODAY. KCOS COULD SEE GUSTS NR 20 KTS THIS AFTERNOON...WITH WINDS AT KALS AND KPUB EXPECTED TO NOT BE QUITE AS STRONG. && .PUB WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 7 PM MDT THIS EVENING FOR COZ226-234-236. && $$
AREA FORECAST DISCUSSION
NWS DENVER CO
929 AM MDT THU OCT 18 2012 .UPDATE...NO CHANGES PLANNED AT THIS TIME BUT WILL NEED TO KEEP AN EYE ON ZONES ADJACENT TO THE HIGH WIND WARNING TO SEE IF THEY NEED TO BE ADDED...MAINLY CONCERNED WITH ZONES 38 AND 44. LONGMONT ANTICYCLONE STILL CONTINUING IN THE DENVER AREA BUT SHOULD BREAK DOWN LATER THIS MORNING AS STRONGER NORTHWESTERLY WINDS MIX DOWN TO THE SURFACE. && .AVIATION...NO CHANGES AT THIS TIME. LONGMONT ANTICYCLONE STILL OCCURRING IN THE DENVER AREA BUT SHOULD BREAK DOWN LATE MORNING/EARLY AFTN AS STRONGER NORTHWEST WINDS MIX DOWN TO THE SURFACE. WILL KEEP TIMING OF THE CURRENT TAF REGARDING ANY WIND SHIFTS AT THIS TIME. && .PREV DISCUSSION... /ISSUED 322 AM MDT THU OCT 18 2012/ SHORT TERM...STG NWLY FLOW ALOFT WIL CONTINUE OVER THE AREA TODAY WITH A VERY DRY AIRMASS IN PLACE. BIGGEST CONCERN FROM LATE MORNING THRU THE MID AFTN HOURS WILL BE HIGH WND POTENTIAL OVER THE FAR NERN PLAINS. 50-60 KT FLOW IN THE 800-700 MB LAYER COULD MIX DOWN TO THE SFC AND PRODUCE SOME WIND GUSTS TO 60 MPH MAINLY EAST OF NEW RAYMER TO AKRON LINE FM 15Z-21Z. MEANWHILE WITH GUSTY WINDS AND LOW HUMIDITY LEVELS BY EARLY AFTN WILL CONTINUE WITH RED FLAG WARNING AND EXPAND IT A BIT FURTHER WEST AND SOUTH AS WELL OVER NERN CO. HIGHS THIS AFTN LOOK SIMILAR TO WED AS 850-700 MM TEMPS DO NOT CHANGE MUCH. FOR TONIGHT WINDS WILL REMAIN GUSTY OVER THE FAR NERN PLAINS THROUGH THE EARLY EVENING HOURS HOWEVER SPEEDS SHOULD BE BELOW WARNING CRITERIA. LONG TERM...UPPER RIDGING IS PROGGED ACROSS COLORADO FRIDAY INTO SATURDAY WITH WEAKER NORTHWESTERLY FLOW ALOFT. ON SATURDAY...THE FLOW ALOFT IS ZONAL...THEN SOUTHWESTERLY BY LATE SATURDAY NIGHT. THE SYNOPTIC SCALE ENERGY IS BENIGN FRIDAY THROUGH SATURDAY NIGHT. THE LOW LEVEL PRESSURE AND WIND FIELDS SHOW WEAK TROUGHING EAST OF THE MOUNTAINS ALL FOUR PERIODS. NORMAL DIURNAL PATTERNS MAY WIN OUT BUT THERE COULD BE SOME DOWNSLOPING AT TIMES. WINDS WILL DEFINITELY BE LESS SIGNIFICANT AS THEY THEY HAVE BEEN LATELY. MOISTURE-WISE...THERE IS SOME NOW AND AGAIN PROGGED IN THE UPPER LEVELS ALL FOUR PERIODS...BUT THE LOWER AND MID LEVELS ARE QUITE DRY. `PRECIPITABLE WATER VALUES ARE IN THE 0.20 TO 0.35 INCH RANGE ALL FOUR PERIODS. THERE IS NO MEASURABLE PRECIPITATION PROGGED ON THE QPF FIELDS FRIDAY THROUGH SATURDAY NIGHT. NO POPS. WINDS SHOULD NOT BE AN ISSUE. FOR TEMPERATURES...FRIDAY`S HIGHS ARE 4-8 C WARMER THAN TODAY`S. SATURDAY`S WARM-UP ANOTHER 1-3 C OVER FRIDAY`S. MOS GUIDANCE VALUES ARE INFLATED AGAIN. FOR THE LATER DAYS...SUNDAY THROUGH WEDNESDAY...MODELS BASICALLY HAVE ZONAL FLOW ALOFT ON SUNDAY...THEN SOUTHWESTERLY LATE SUNDAY NIGHT THROUGH WEDNESDAY. THE GFS HAS A WEAK UPPER TROUGH TO MOVE ACROSS SUNDAY AFTERNOON...THE ECMWF DOES NOT. WIND SPEEDS ALOFT ARE MODERATE ON SUNDAY THROUGH MONDAY NIGHT...THEN THEY INCREASE. BY WEDNESDAY... SPEEDS OVER THE CWA ARE AROUND 100 KNOTS AT JET LEVEL...WITH A JET MAX MOVING INTO NORTHWEST COLORADO BY WEDNESDAY EVENING ACCORDING TO THE GFS. ON WEDNESDAY...THE GFS HAS A BROAD MEAN TROUGH DEEPENING OVER THE WESTERN UNITED STATES. THE ECMWF SHOWS A MORE FLAT TROUGH. MOISTURE IS POOR...BUT INCREASES A BIT LATER ON WEDNESDAY. TEMPERATURES ARE ABOVE NORMALS. AVIATION...WITH NWLY FLOW COMING OFF THE CHEYENNE RIDGE CURRENTLY HAVE AN LONGMONT ANTICYCLONE IN PLACE NEAR DENVER. THE HRRR AND TO SOME EXTENT THE RAP HAVE THIS FEATURE CENTERED OVER SWRN WELD COUNTY BY MIDDAY. AS A RESULT WINDS EARLY THIS MORNING HAVE BEEN SELY WHICH SHOULD SHIFT TO MORE SLY BY 12Z. BY 18Z WINDS SHOULD BECOME MORE NNWLY WITH INCREASING SPEEDS BY EARLY AFTN. SOME GUSTS IN THE 25-30 KT RANGE WILL BE POSSIBLE THRU LATE AFTN. WINDS SHOULD GRADUALLY DECREASE BY 00Z AND THEN BECOME MORE WSW AFTER SUNSET AND THEN SSW BY 06Z. && .BOU WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING UNTIL 6 PM MDT THIS EVENING FOR COZ042-048>051. RED FLAG WARNING UNTIL 6 PM MDT THIS EVENING FOR COZ238-241>251. && $$ SHORT TERM...COOPER/RPK LONG TERM....RJK AVIATION...COOPER
AREA FORECAST DISCUSSION
NWS PUEBLO CO
402 AM MDT THU OCT 18 2012 .SHORT TERM... (TODAY AND TONIGHT) SO FAR TEMPS OVR THE SERN PLAINS HAVE NOT GONE BELOW FREEZING AND HAVE BEEN IN THE MID AND UPR 30S...BUT DEW POINTS REMAIN QUITE LOW AND THERE IS STILL TIME FOR TEMPS TO FALL BELOW FREEZING THIS MORNING. THUS WL LEAVE THE FREEZE WARNING IN EFFECT. MAIN CONCERN TODAY IS THE POTENTIAL FOR RED FLAG CONDITIONS. WITH A DRY AIR MASS IN PLACE OVR THE AREA...DEW POINTS TODAY WL BE QUITE LOW AND MIN RH VALUES ARE EXPECTED TO BE BELOW 15 PERCENT AT THE LOWER ELEVATIONS. BRISK DRY NW FLOW WL BE FOUND OVR THE AREA TODAY...ALTHOUGH GENERALLY NOT QUITE AS STRONG AS YESTERDAY IN MOST AREAS. THE STRONGEST GRADIENT WL BE OVR THE FAR SERN PLAINS...AND IT LOOKS LIKE GUSTS WL MEET RED FLAG CRITERIA THIS AFTERNOON OVR KIOWA COUNTY AND A GOOD PORTION OF PROWERS COUNTY...SO WL ISSUE RED FLAG WARNING. THE HRRR AND LOCAL WRF ARE SHOWING GUSTS ALSO MEETING CRITERIA OVR NRN EL PASO COUNTY...MAINLY EAST OF THE INTERSTATE SO WL ALSO ISSUE A WARNING FOR THIS AREA. THERE ARE TWO OTHER AREAS OF CONCERN...THE FAR EASTERN AREAS OF SRN EL PASO COUNTY (FIRE ZONE 227) AND THE NRN PORTIONS OF THE SAN LUIS VALLEY (FIRE ZONE 224)...WHERE GUSTS ARE ALSO EXPECTED TO REACH RED FLAG WARNING CRITERIA THIS AFTERNOON. THE PORTIONS OF THESE FIRE ZONES WHERE THE GUSTS WL PROBABLY MEET CRITERIA SEEM TOO LOCALIZED TO ISSUE RED FLAG WARNINGS FOR THE ENTIRE ZONE...SO WL NOT ISSUE A HIGHLIGHT AT THIS TIME. FOR TONIGHT...THE WEATHER WL REMAIN DRY WITH LITTLE IF ANY CLOUDS. SOME AREAS...MAINLY ALONG THE ARKANSAS RIVER VALLEY...MAY AGAIN SEE LOW TEMPS FALL BELOW 32 DEGREES. WL HAVE TO WAIT AN SEE IF WE GET A FREEZE THIS MORNING TO SEE IF A HIGHLIGHT MAY BE NEEDED TONIGHT. .LONG TERM... (FRIDAY THROUGH WEDNESDAY) ...WARM AND DRY THROUGH THE WEEKEND... FRIDAY-SUNDAY...MODELS REMAIN IN GOOD AGREEMENT THROUGH THE WEEKEND AS MODERATING NORTHWEST FLOW ALOFT ACROSS THE REGION ON FRIDAY BECOMES MORE WEST TO SOUTHWEST SATURDAY AND INCREASES AGAIN ON SUNDAY WITH PAC NORTHWEST ENERGY DIGGING ACROSS THE GREAT BASIN AND NORTHERN TIER OF STATES. MODELS ALSO INDICATING THE WEAKENING REMNANTS OF POST TROPICAL SYSTEM PAUL LIFTING OUT ACROSS THE DESERT SOUTHWEST ON SUNDAY. WARMING ALOFT PROGGED ACROSS THE AREA FRIDAY AND SATURDAY ALONG WITH DOWNSLOPE FLOW WILL ALLOW FOR TEMPERATURES TO WARM BACK TO ABOVE SEASONAL AVERAGES...ESPECIALLY ON SATURDAY WITH HIGHS EXPECTED TO BE IN THE 70S AND 80S ACROSS THE EASTERN PLAINS WITH MAINLY 50S AND 60S ACROSS THE HIGHER TERRAIN. DEVELOPING DOWNSLOPE FLOW AND THE WARMING ALOFT WILL ALSO ALLOW FOR WARMER OVERNIGHT LOWS...ESPECIALLY OVER AND NEAR THE HIGHER TERRAIN. A WEAK NORTHERLY SURGE/COLD FRONT AND COOLING ALOFT AHEAD OF PAC NORTHWEST TROUGH WILL BRING ONLY SLIGHTLY COOLER TEMPERATURES ACROSS THE AREA ON SUNDAY. MONDAY-WEDNESDAY...LESSER CONFIDENCE FORECAST...ESPECIALLY FOR THE MIDDLE OF THE WEEK AND BEYOND...WITH MODELS DIFFERING ON AMPLITUDE AND MOVEMENT OF PACIFIC ENERGY DIGGING INTO THE GREAT BASIN AND ROCKIES. MODELS DO AGREE THAT THE REMNANTS OF THE TROPICAL SYSTEM TO REMAIN WELL SOUTH OF THE AREA AS IT CONTINUES TO WEAKEN AND LIFT OUT ACROSS SOUTHERN NEW MEXICO AND THE SOUTHERN HIGH PLAINS. THE LATEST GFS REMAINS THE DEEPEST SOLUTION WITH MODERATE AND MAINLY DRY SOUTHWEST FLOW ACROSS THE STATE THROUGH WEDNESDAY WITH A STAND UP PACIFIC COLD FRONT MOVING ACROSS THE STATE WEDNESDAY AND WEDNESDAY NIGHT. THE ECMWF IS FASTER AND LESS AMPLIFIED WITH THE SYSTEM AND MOVES THE FRONT ACROSS THE AREA MONDAY NIGHT AND TUESDAY WITH A SECONDARY SURGE OF COLD AIR MOVING ACROSS THE AREA WEDNESDAY NIGHT AND THURSDAY. AT ANY RATE...PATTERN WOULD SUGGEST BEST CHANCES OF PRECIP TO BE ACROSS THE HIGHER TERRAIN ALONG AND WEST OF THE CONTDVD WITH TEMPERATURES SLOWLY COOLING BACK TO AT OR BELOW SEASONAL AVERAGES BE THE MIDDLE OF THE WEEK. -MW && .AVIATION... WITH DRY NW FLOW IN PLACE...FEW IS ANY CLOUDS ARE EXPECTED TODAY AND TONIGHT AND THUS VFR CONDITIONS WL BE FOUND ACRS THE AREA. SOME AREAS WL SEE BREEZY NORTHWEST WINDS TODAY. KCOS COULD SEE GUSTS NR 20 KTS THIS AFTERNOON...WITH WINDS AT KALS AND KPUB EXPECTED TO NOT BE QUITE AS STRONG. && .PUB WATCHES/WARNINGS/ADVISORIES... FREEZE WARNING UNTIL 8 AM MDT THIS MORNING FOR COZ083-086-088- 093>099. RED FLAG WARNING FROM NOON TODAY TO 7 PM MDT THIS EVENING FOR COZ226-234-236. && $$ 28/23
AREA FORECAST DISCUSSION
NWS DENVER CO
322 AM MDT THU OCT 18 2012 .SHORT TERM...STG NWLY FLOW ALOFT WIL CONTINUE OVER THE AREA TODAY WITH A VERY DRY AIRMASS IN PLACE. BIGGEST CONCERN FROM LATE MORNING THRU THE MID AFTN HOURS WILL BE HIGH WND POTENTIAL OVER THE FAR NERN PLAINS. 50-60 KT FLOW IN THE 800-700 MB LAYER COULD MIX DOWN TO THE SFC AND PRODUCE SOME WIND GUSTS TO 60 MPH MAINLY EAST OF NEW RAYMER TO AKRON LINE FM 15Z-21Z. MEANWHILE WITH GUSTY WINDS AND LOW HUMIDITY LEVELS BY EARLY AFTN WILL CONTINUE WITH RED FLAG WARNING AND EXPAND IT A BIT FURTHER WEST AND SOUTH AS WELL OVER NERN CO. HIGHS THIS AFTN LOOK SIMILAR TO WED AS 850-700 MM TEMPS DO NOT CHANGE MUCH. FOR TONIGHT WINDS WILL REMAIN GUSTY OVER THE FAR NERN PLAINS THROUGH THE EARLY EVENING HOURS HOWEVER SPEEDS SHOULD BE BELOW WARNING CRITERIA. .LONG TERM...UPPER RIDGING IS PROGGED ACROSS COLORADO FRIDAY INTO SATURDAY WITH WEAKER NORTHWESTERLY FLOW ALOFT. ON SATURDAY...THE FLOW ALOFT IS ZONAL...THEN SOUTHWESTERLY BY LATE SATURDAY NIGHT. THE SYNOPTIC SCALE ENERGY IS BENIGN FRIDAY THROUGH SATURDAY NIGHT. THE LOW LEVEL PRESSURE AND WIND FIELDS SHOW WEAK TROUGHING EAST OF THE MOUNTAINS ALL FOUR PERIODS. NORMAL DIURNAL PATTERNS MAY WIN OUT BUT THERE COULD BE SOME DOWNSLOPING AT TIMES. WINDS WILL DEFINITELY BE LESS SIGNIFICANT AS THEY THEY HAVE BEEN LATELY. MOISTURE-WISE...THERE IS SOME NOW AND AGAIN PROGGED IN THE UPPER LEVELS ALL FOUR PERIODS...BUT THE LOWER AND MID LEVELS ARE QUITE DRY. `PRECIPITABLE WATER VALUES ARE IN THE 0.20 TO 0.35 INCH RANGE ALL FOUR PERIODS. THERE IS NO MEASURABLE PRECIPITATION PROGGED ON THE QPF FIELDS FRIDAY THROUGH SATURDAY NIGHT. NO POPS. WINDS SHOULD NOT BE AN ISSUE. FOR TEMPERATURES...FRIDAY`S HIGHS ARE 4-8 C WARMER THAN TODAY`S. SATURDAY`S WARM-UP ANOTHER 1-3 C OVER FRIDAY`S. MOS GUIDANCE VALUES ARE INFLATED AGAIN. FOR THE LATER DAYS...SUNDAY THROUGH WEDNESDAY...MODELS BASICALLY HAVE ZONAL FLOW ALOFT ON SUNDAY...THEN SOUTHWESTERLY LATE SUNDAY NIGHT THROUGH WEDNESDAY. THE GFS HAS A WEAK UPPER TROUGH TO MOVE ACROSS SUNDAY AFTERNOON...THE ECMWF DOES NOT. WIND SPEEDS ALOFT ARE MODERATE ON SUNDAY THROUGH MONDAY NIGHT...THEN THEY INCREASE. BY WEDNESDAY... SPEEDS OVER THE CWA ARE AROUND 100 KNOTS AT JET LEVEL...WITH A JET MAX MOVING INTO NORTHWEST COLORADO BY WEDNESDAY EVENING ACCORDING TO THE GFS. ON WEDNESDAY...THE GFS HAS A BROAD MEAN TROUGH DEEPENING OVER THE WESTERN UNITED STATES. THE ECMWF SHOWS A MORE FLAT TROUGH. MOISTURE IS POOR...BUT INCREASES A BIT LATER ON WEDNESDAY. TEMPERATURES ARE ABOVE NORMALS. && .AVIATION...WITH NWLY FLOW COMING OFF THE CHEYENNE RIDGE CURRENTLY HAVE AN LONGMONT ANTICYCLONE IN PLACE NEAR DENVER. THE HRRR AND TO SOME EXTENT THE RAP HAVE THIS FEATURE CENTERED OVER SWRN WELD COUNTY BY MIDDAY. AS A RESULT WINDS EARLY THIS MORNING HAVE BEEN SELY WHICH SHOULD SHIFT TO MORE SLY BY 12Z. BY 18Z WINDS SHOULD BECOME MORE NNWLY WITH INCREASING SPEEDS BY EARLY AFTN. SOME GUSTS IN THE 25-30 KT RANGE WILL BE POSSIBLE THRU LATE AFTN. WINDS SHOULD GRADUALLY DECREASE BY 00Z AND THEN BECOME MORE WSW AFTER SUNSET AND THEN SSW BY 06Z. && .BOU WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING FROM 9 AM THIS MORNING TO 6 PM MDT THIS EVENING FOR COZ042-048>051. RED FLAG WARNING FROM NOON TODAY TO 6 PM MDT THIS EVENING FOR COZ238-241>251. && $$ SHORT TERM...RPK LONG TERM....RJK AVIATION...RPK
AREA FORECAST DISCUSSION
NWS TAUNTON MA
747 PM EDT FRI OCT 19 2012 .SYNOPSIS... PERIODS OF RAIN...WITH BRIEF HEAVY DOWNPOURS AND ISOLATED THUNDERSTORMS...WILL MOVE ACROSS THE REGION AS AN OCCLUDED FRONT SLOWLY PUSHES THROUGH TONIGHT AND EARLY SATURDAY. DRIER AND MILD CONDITIONS WILL RETURN LATER SATURDAY. A DRY COLD FRONT SWEEPS ACROSS THE AREA SUNDAY...DELIVERING COOLER AND BRISK CONDITIONS INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 730 PM UPDATE... 19/20Z HRRR LOOKS TO HAVE A VERY GOOD HANDLE ON THE OVERALL AREAS OF SHOWERS OVERNIGHT...NOT FOR SPECIFIC LOCATIONS PER SE...BUT IN MODELING A BRIEF BREAK IN THE ACTION THIS EVENING. AS SUCH USED IT HEAVILY TO MODIFY POPS THIS EVENING. THE TIMING MAY NOT BE PERFECT THOUGH...SO IT WILL NEED TO BE MONITORED THIS EVENING. THUNDERSTORMS ARE FEW AND FAR BETWEEN THIS EVENING DUE TO THE POOR INSTABILITY OVER OUR REGION. KEPT A MENTION OF ISOLATED THUNDERSTORMS BECAUSE THEY ARE POSSIBLE...BUT VERY DIFFICULT TO NAIL DOWN WHICH LOCATIONS MAY GET ONE. LOCATIONS TOWARD THE EAST COAST ARE FAVORED. OTHERWISE...ONLY MINOR TWEAKS TO TEMPERATURES AND DEW POINTS TO REFLECT THE LATEST OBSERVATIONS. PREVIOUS DISCUSSION... BANDS OF SHOWERS WERE SHIFTING N ACROSS THE REGION AROUND LARGE CYCLONIC CIRCULATION DUE TO AN UPPER LOW AND SURFACE SYSTEM ACROSS THE GREAT LAKES AT 20Z. CLOUDS DID BREAK FOR A TIME ACROSS EASTERN MA/RI EARLY THIS AFTERNOON...WHICH ONLY ADDED SOME INSTABILITY TO THE ALREADY UNSTABLE AIRMASS AND ALLOWED MORE SHOWERS TO DEVELOP IN THE MOIST LOW LEVEL S WIND FLOW. CONTINUE TO MONITOR DEVELOPING SURFACE WAVE OFF THE MID ATLC COAST WITH AREA OF SHOWERS/TSTMS THAT ARE SHIFTING N-NE WITH TIME. SHORT RANGE MODELS IN GOOD AGREEMENT IN BRINGING THIS WAVE...PUSHING NEXT AREA OF SHOWERS/ISOLD TSTMS ACROSS CENTRAL AND EASTERN AREAS MAINLY AROUND OR AFTER 02Z. HAVE KEPT CAT POPS GOING THERE... ESPECIALLY ACROSS E MA AFTER MIDNIGHT AS OCCLUDED FRONT WORKS E. PRECIP WILL TAPER OFF ACROSS THE CT VALLEY AND E SLOPES OF THE BERKSHIRES TOWARD DAYBREAK...WITH BEST CHANCE OF PRECIP ALONG THE COAST. STILL SOME MARGINAL INSTABILITY WORKING INTO THE REGION WITH THIS WAVE...SO HAVE KEPT MENTION OF ISOLD THUNDER IN THE FORECAST. MAY ALSO SEE SOME GUSTS UP TO 20-25 KT ALONG THE S COAST EARLY TONIGHT. WILL REMAIN RATHER MILD FOR MID TO LATE OCTOBER TONIGHT...WITH LOWS ONLY FALLING BACK TO THE MID 50S TO LOWER 60S. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... SATURDAY... BACK EDGE OF PRECIP AND FRONT WILL PUSH OFFSHORE DURING SATURDAY MORNING...BUT NOT MUCH COLD AIR TO SPEAK OF BEHIND THIS FRONT AS UPPER LOW REMAINS WELL NW OF THE REGION THROUGH THE DAY. LAST OF PRECIP SHOULD MOVE OFF CAPE COD BY MIDDAY...THEN IMPROVING CONDITIONS WILL MOVE IN. EXPECT DAYTIME HIGHS TO REACH THE LOWER 70S FOR MOST AREAS AS SUN BREAKS THROUGH DURING THE LATE MORNING AND AFTERNOON. AS WINDS VEER FROM SW TO W...MAY SEE SOME GUSTS UP TO AROUND 20 KT ALONG THE S COAST. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... HIGHLIGHTS... * MAINLY DRY AND SEASONABLE WEATHER SUNDAY INTO MUCH OF NEXT WEEK 19/12Z GUIDANCE SUITE IS IN DECENT AGREEMENT WITH THE OVERALL SYNOPTIC PATTERN INTO WEDNESDAY. AFTER THAT POINT IN TIME THOUGH...THE DIFFERENCES IN HOW THE VARIOUS MODELS HANDLE THE INTERACTION OF SEVERAL SHORTWAVES WITH A WESTERN USA MID-LEVEL TROUGH BECOME SIGNIFICANT. HAVE AVERAGE CONFIDENCE IN THE FORECAST DETAILS THROUGH TUESDAY NIGHT AND BELOW AVERAGE CONFIDENCE THEREAFTER. AS SUCH...BASED THIS PORTION OF THE FORECAST OFF OF A GFS/NAM BLEND THROUGH MONDAY. THEN USED HPC GUIDANCE...WHICH RELIED HEAVILY UPON THE ECMWF ENSEMBLE MEAN SOLUTION...FOR THE REST OF NEXT WEEK. SUNDAY... NOTICEABLY COOLER /BUT CLOSE TO NORMAL/ ALONG WITH A BRISK WEST WIND. MORNING SUNSHINE WILL LIKELY GIVE WAY TO LOTS OF DIURNAL CLOUDS GIVEN CYCLONIC FLOW ALOFT AND STEEPENING LAPSE RATES. THIS MAY LEAD TO A FEW AFTERNOON/EVENING SHOWERS. HIGHEST POPS WILL BE TOWARD THE HIGHER TERRAIN OF NORTHWEST MA AND SOUTHWEST NH WHERE UPSLOPE FLOW WILL CONTRIBUTE TO HIGHER POPS. EXPECTING MOST OF SOUTHERN NEW ENGLAND TO BE DRY. MONDAY THROUGH WEDNESDAY... MID-LEVEL LONGWAVE PATTERN EARLY NEXT WEEK SHOULD FEATURE AN EAST COAST RIDGE WITH A BROAD TROUGH WEST OF THE MISSISSIPPI RIVER. SOME OF THE 12Z GUIDANCE MEMBERS CLOSE OFF A PAIR OF LOWS...ONE OVER SASKATCHEWAN AND ANOTHER OFF THE PACIFIC NORTHWEST COAST. THE JET STREAM IS EXPECTED TO BECOME SUPPRESSED FARTHER SOUTH...WHICH IS CONSISTENT WITH TELECONNECTIONS AS BOTH THE NAO AND AO BECOMING INCREASINGLY NEGATIVE NEXT WEEK. AS FOR PRECIPITATION... SUBTROPICAL RIDGE BECOMES ELONGATED FROM WEST TO EAST ACROSS THE SOUTHERN STATES...PRECLUDING MUCH MOISTURE FROM THE GULF OF MEXICO OR ATLANTIC TO STREAM POLEWARD INTO NEW ENGLAND. THUS WEATHER SYSTEMS IMPACTING OUR REGION DURING THIS TIME WILL HAVE LIMITED MOISTURE WITH PACIFIC ORIGINS. AS A RESULT NOT EXPECTING ANY BIG RAINFALL EVENTS NEXT WEEK FOR NEW ENGLAND. GREATEST RISK OF SHOWERS /ALBEIT A LOW RISK/ APPEARS IN THE TUE - WED TIME FRAME WHEN WARM FRONTAL BOUNDARY MAKES A RUN AT SOUTHERN ENGLAND. THURSDAY THROUGH FRIDAY... LOTS OF DIFFERENCES WITH THE TRACK AND TIMING OF A LOW PRESSURE MOVING TOWARD THE GREAT LAKES. HAVE VERY LITTLE CONFIDENCE IN THE DETAILS FOR THIS TIME PERIOD. AT THIS POINT HAVE KEPT THE FORECAST DRY WITH MOST OF THE INGREDIENTS STAYING TO OUR WEST. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT MODERATE...30 PERCENT TO 60 PERCENT HIGH...GREATER THAN 60 PERCENT OVERVIEW...LOW TO MODERATE CONFIDENCE. TONIGHT...CIGS/VSBYS SHOULD LOWER TO MVFR-IFR WITH LOW LEVEL MOISTURE IN PLACE AS WELL AS HIGH DEWPTS. BEST CHANCE FOR PRECIP WILL OCCUR ACROSS CENTRAL AND EASTERN AREAS...WITH SPOTTY BRIEF LIFR CONDITIONS. LIFR VSBYS DEVELOPING AFTER 05Z ACROSS CT VALLEY INTO S NH AND HIGHER TERRAIN OF CENTRAL MA. ISOLD TSRA POSSIBLE TOWARD THE EAST COAST AS WELL EARLY THIS EVENING. SATURDAY...STARTING OFF WITH MVFR-IFR CONDITIONS EARLY...BUT EXPECT IMPROVEMENT TO VFR FROM W-E DURING THE MORNING AS PRECIP MOVES OFFSHORE. S-SW WINDS SHIFT TO W WITH SOME GUSTS TO AROUND 20 KT. KBOS TAF...LOW TO MODERATE CONFIDENCE IN TAF. VFR CONDITIONS THROUGH AROUND 21Z...THEN CIGS MAY LOWER TO MVFR WITH PASSING SHOWERS. EXPECT CIGS/VSBYS TO LOWER TO MVFR-IFR AFTER 02Z WITH LIFR CIGS AFTER 06Z. CONDITIONS SHOULD IMPROVE BY MIDDAY SATURDAY. GUSTY E-SE WINDS THROUGH THIS EVENING WHICH WILL SHIFT TO S EARLY TONIGHT. MAY SEE LLWS WITH S-SE WINDS 35-40 KT OFF DECK THROUGH 00Z. KBDL TAF...MODERATE CONFIDENCE IN TAF. WILL SEE PERIODS OF MVFR-IFR CIGS/VSBYS IN SHOWERS AND PATCHY FOG. MAY SEE IFR-LIFR CIGS/VSBYS AFTER 06Z IN DEVELOPING NOCTURNAL FOG. CONDITIONS SHOULD IMPROVE TO VFR BY 14Z-15Z. MAY SEE LLWS WITH S-SE WINDS UP TO 40 KT OFF DECK THROUGH 00Z. OUTLOOK...SATURDAY THROUGH WEDNESDAY... SATURDAY...MODERATE TO HIGH CONFIDENCE. IFR/MVFR IN DRIZZLE/FOG EARLY WILL TREND TO VFR FROM WEST TO EAST. SUNDAY-TUESDAY...HIGH CONFIDENCE FOR VFR CONDITIONS. BRISK WNW SUN AND MON. WEDNESDAY...MODERATE CONFIDENCE FOR VFR. && .MARINE... HIGH CONFIDENCE. HAVE KEPT SMALL CRAFTS GOING AS 25 KT GUSTS STILL POSSIBLE AS LOW PRES APPROACHES FROM THE S. SEAS UP TO 7 FT REPORTED FROM THE BUOYS ON THE SOUTHERN OUTER WATERS...SO ALSO CONTINUED FOR THIS ASPECT. GUSTS HAVE DIMINISHED ON BOSTON HARBOR AND NARRAGANSETT BAY SO ENDED THE SMALL CRAFT ON THOSE WATERS. EXPECT WINDS AND SEAS TO REMAIN AOA SMALL CRAFT CRITERIA THROUGH SATURDAY...THOUGH WILL START TO DIMINISH DURING THE DAY ON THE NEAR SHORE WATERS. OUTLOOK...SATURDAY NIGHT THROUGH WEDNESDAY... HIGH CONFIDENCE DRY WEATHER ALONG WITH BRISK WNW WINDS SUN AND MON PROVIDING GOOD VSBY. LEFTOVER SE SWELLS WILL GRADUALLY SUBSIDE. SMALL CRAFT ADVISORY CONDITIONS LIKELY TO PERSIST THROUGH MONDAY ACROSS THE OUTER COASTAL WATERS. MORE TRANQUIL CONDITIONS EXPECTED TUE AND WED. && .HYDROLOGY... APPEARS HEAVIEST RAINFALL THROUGH MID AFTERNOON CONFINED ACROSS THE WESTERN CT VALLEY AND E SLOPES OF THE BERKSHIRES...WITH UP TO 1-1.5 INCHES SO FAR AND 2 INCHES OR SO ACROSS THE MID HUDSON VALLEY. ABOUT 0.25 TO 0.75 INCHES FOR MOST OTHER AREAS...LOWEST ACROSS THE E COAST...CAPE COD AND THE ISLANDS...SO FAR. EXPECT NEXT WAVE OF LOW PRES WILL CONTINUE TO WORK N-NE TOWARD THE REGION EARLY TONIGHT. WILL LIKELY SEE BRIEF HEAVY DOWNPOURS ACROSS CENTRAL AND EASTERN AREAS TONIGHT...WHICH MAY CAUSE LOCALIZED POOR DRAINAGE AND URBAN FLOODING DUE TO FALLEN LEAVES CLOGGING CATCH BASINS. WILL CONTINUE TO MONITOR THIS FEATURE. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ231-232. SMALL CRAFT ADVISORY UNTIL 6 AM EDT SATURDAY FOR ANZ233-234. SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ235-237-250- 254>256. SMALL CRAFT ADVISORY UNTIL 6 PM EDT SATURDAY FOR ANZ251. && $$ SYNOPSIS...EVT/BELK NEAR TERM...BELK/EVT SHORT TERM...EVT LONG TERM...BELK AVIATION...EVT/BELK MARINE...EVT/BELK HYDROLOGY...EVT
AREA FORECAST DISCUSSION
NWS MIAMI FL
128 PM EDT THU OCT 18 2012 .AVIATION...VFR WILL PREVAIL. A FEW TSRA IS POSSIBLE ACROSS THE EAST COAST TERMINALS SO MAINTAINED VCTS, ALTHOUGH THIS RISK MAY HAVE LOWERED A BIT DUE TO THE FACT THAT LOW LEVEL WINDS HAVE INCREASED OUT OF THE SOUTHWEST AS PER ACARS DATA. THIS WILL LIKELY KEEP SURFACE WINDS PREVAILING OUT OF THE SSW, BUT DIFFICULT WIND FORECAST AS SOME OBS CONTINUE SE. LIGHT WINDS, TRANQUIL CONDITIONS WILL PREVAIL TONIGHT WITH A FEW SHOWERS POSSIBLE ON FRI, AND MAYBE A TSTORM. /GREGORIA && .PREV DISCUSSION... /ISSUED 1000 AM EDT THU OCT 18 2012/ UPDATE... UPDATED THE SHORT TERM FORECAST TO INCREASE THE POPS ACROSS THE REGION. THE 12Z SOUNDING AND OTHER REGIONAL PWAT REPORTS INDICATE AN INCREASING TREND IN MOISTURE ACROSS THE REGION WITH REGIONAL PWATS NEAR 2 INCHES. IN ADDITION THE RECENT GUIDANCE AND RECENT WATER VAPOR IMAGERY CONTINUE TO INDICATE A MID TO UPPER LEVEL SHORT WAVE ENTERING THE EASTERN GULF AND FLORIDA STRAITS. AND EARLIER THIS MORNING THERE WAS CONSIDERABLE CONVECTION IN THE VICINITY OF THE CENTRAL FLORIDA KEYS. GIVEN ALL THESE FACTORS...THERE COULD BE ISOLATED AREAS OF HEAVY RAINFALL ALTHOUGH THUNDERSTORM ACTIVITY IS EXPECTED TO BE ISOLATED. THE CONVECTION IS MAINLY EXPECTED TO INCREASE DURING THE EARLY AFTERNOON THROUGH THE EVENING HOURS. 60 PREV DISCUSSION... /ISSUED 724 AM EDT THU OCT 18 2012/ AVIATION...PLENTY OF LINGERING LOW-LEVEL MOISTURE AND CLOUD COVERAGE WITH BASES RANGING FROM 6-10 KFT WILL REMAIN IN PLACE THIS MORNING. SOME OF THE INTERIOR AREAS MAY EVEN EXPERIENCE BRIEF PERIODS WITH REDUCED VISIBILITIES IF ANY OF THIS CLOUD COVERAGE CLEARS...WITH THE BEST CHANCE INLAND AWAY FROM THE IMMEDIATE COAST. AS THE DAY PROGRESSES...PLENTY OF LOW-LEVEL MOISTURE UP TO 10-13 KFT COMBINED WITH WHAT IS LEFT OF AN OLD FRONTAL BOUNDARY WILL KEEP THE RAIN CHANCES IN THE FORECAST TODAY. THE LATEST WRF AND HRRR MODEL REFLECTIVITIES INDICATE MAINLY SCATTERED SHOWERS REMAINING POSSIBLE ONCE AGAIN THROUGH THE LATE MORNING AND AFTERNOON PERIODS. WESTERLY DEEP LAYER STEERING FLOW WILL FAVOR THE BEST SHOWER COVERAGE ACROSS THE INTERIOR AND EASTERN HALF OF THE PENINSULA...SIMILAR TO YESTERDAY. PREV DISCUSSION... /ISSUED 244 AM EDT THU OCT 18 2012/ DISCUSSION...LARGE SCALE MID LEVEL TROUGH IS CURRENTLY CENTERED OVER THE UPPER MISSISSIPPI VALLEY. A SHORT WAVE TROUGH EMBEDDED IN THIS FLOW MOVED ACROSS SOUTH FLORIDA WEDNESDAY AFTERNOON GENERATING SOME HEAVY THUNDERSTORMS ACROSS THE NORTHEAST PORTION OF THE REGION WITH ISOLATED LOCATIONS RECEIVING OVER FOUR INCHES OF RAINFALL. THIS TROUGH HAS LIFTED TO THE NORTHEAST WHILE AT THE SURFACE, A WEAK BOUNDARY IS LOCATED JUST OFF THE SOUTHEAST COAST. SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE BEING GENERATED ALONG THE BOUNDARY. ANOTHER WEAKER SHORT WAVE TROUGH IS LOCATED OVER THE CENTRAL GULF OF MEXICO WHICH IS SOMEWHAT EVIDENT ON WATER VAPOR IMAGERY. THE GFS, NAM AND ECMWF ALL DEPICT THIS FEATURE BUT THE NAM HAS A MORE PRONOUNCED TROUGH AND THUS YIELDS THE HIGHEST POPS. MUCH DRIER AIR ABOVE 10-15K FEET IS CURRENTLY MOVING INTO THE REGION BEHIND THE EXITING TROUGH. WHILE THERE WILL BE SOME INCREASE IN MOISTURE WITH THE SECONDARY TROUGH, IT WOULD APPEAR THE NAM IS SUFFERING ONCE AGAIN FROM MESOSCALE BIAS. THE TROUGH AXIS WILL CONTINUE THE SOUTHWEST STEERING FLOW ACROSS SOUTH FLORIDA SO ANYTHING THAT DEVELOPS OVER THE INTERIOR WILL MOVE AGAIN TOWARDS THE EAST COAST METRO AREA. THE RAPID REFRESH WHICH PERFORMED VERY WELL WITH YESTERDAY`S CONVECTION AND ITS CURRENT RUN GOES OUT THROUGH 18Z, SHOWS SOME DEVELOPMENT BEGINNING AROUND 17Z BUT DOES NOT GET TOO AGGRESSIVE. SO THAT BEING SAID HAVE LEANED CLOSER TO THE MAV NUMBERS WHICH IS QUITE A BIT LESS FROM THE MET GUIDANCE. ALL MODEL GUIDANCE NOW SHOWS THE MAIN TROUGH LIFTING TO THE NORTHEAST THROUGH SATURDAY AS A STRONG TROUGH DEVELOPS IN THE NORTH PACIFIC. THIS WILL ALLOW FOR THE DRIER AIR MASS TO FILTER DOWN ACROSS THE PENINSULA ON SATURDAY INTO EARLY NEXT WEEK WITH DEW POINTS ALSO DROPPING INTO THE 60S. SO A COUPLE MORE DAYS OF THE HIGHER HUMIDITY AND MORE PLEASANT CONDITIONS FOR THE WEEKEND AND AT LEAST EARLY NEXT WEEK. MARINE...TRANQUIL WIND AND SEAS ARE EXPECTED THROUGH THE REMAINDER OF THIS WEEK AND THEN ONLY A SLOW INCREASE IN THE SEAS OVER THE WEEKEND AND INTO NEXT WEEK AS THE WIND VEERS TO A MORE NORTH TO NORTHEAST DIRECTION. WIND SPEEDS ARE ANTICIPATED TO REMAIN AT 15 KNOTS OR LESS HOWEVER AND SEAS WILL REMAIN WELL BELOW ADVISORY CRITERIA. FIRE WEATHER...NO PROBLEMS OR CONCERNS IN THE SHORT TERM. THERE WILL BE SOME LOWER RELATIVE HUMIDITIES OVER THE WEEKEND BUT AT THIS TIME IT LOOKS LIKE THEY WILL REMAIN ABOVE 35 PERCENT. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 87 74 87 72 / 50 30 30 20 FORT LAUDERDALE 86 76 87 75 / 50 30 20 20 MIAMI 88 75 88 75 / 50 30 20 20 NAPLES 87 71 86 72 / 50 20 20 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS MIAMI FL
1000 AM EDT THU OCT 18 2012 .UPDATE... UPDATED THE SHORT TERM FORECAST TO INCREASE THE POPS ACROSS THE REGION. THE 12Z SOUNDING AND OTHER REGIONAL PWAT REPORTS INDICATE AN INCREASING TREND IN MOISTURE ACROSS THE REGION WITH REGIONAL PWATS NEAR 2 INCHES. IN ADDITION THE RECENT GUIDANCE AND RECENT WATER VAPOR IMAGERY CONTINUE TO INDICATE A MID TO UPPER LEVEL SHORT WAVE ENTERING THE EASTERN GULF AND FLORIDA STRAITS. AND EARLIER THIS MORNING THERE WAS CONSIDERABLE CONVECTION IN THE VICINITY OF THE CENTRAL FLORIDA KEYS. GIVEN ALL THESE FACTORS...THERE COULD BE ISOLATED AREAS OF HEAVY RAINFALL ALTHOUGH THUNDERSTORM ACTIVITY IS EXPECTED TO BE ISOLATED. THE CONVECTION IS MAINLY EXPECTED TO INCREASE DURING THE EARLY AFTERNOON THROUGH THE EVENING HOURS. 60 && .PREV DISCUSSION... /ISSUED 724 AM EDT THU OCT 18 2012/ AVIATION...PLENTY OF LINGERING LOW-LEVEL MOISTURE AND CLOUD COVERAGE WITH BASES RANGING FROM 6-10 KFT WILL REMAIN IN PLACE THIS MORNING. SOME OF THE INTERIOR AREAS MAY EVEN EXPERIENCE BRIEF PERIODS WITH REDUCED VISIBILITIES IF ANY OF THIS CLOUD COVERAGE CLEARS...WITH THE BEST CHANCE INLAND AWAY FROM THE IMMEDIATE COAST. AS THE DAY PROGRESSES...PLENTY OF LOW-LEVEL MOISTURE UP TO 10-13 KFT COMBINED WITH WHAT IS LEFT OF AN OLD FRONTAL BOUNDARY WILL KEEP THE RAIN CHANCES IN THE FORECAST TODAY. THE LATEST WRF AND HRRR MODEL REFLECTIVITIES INDICATE MAINLY SCATTERED SHOWERS REMAINING POSSIBLE ONCE AGAIN THROUGH THE LATE MORNING AND AFTERNOON PERIODS. WESTERLY DEEP LAYER STEERING FLOW WILL FAVOR THE BEST SHOWER COVERAGE ACROSS THE INTERIOR AND EASTERN HALF OF THE PENINSULA...SIMILAR TO YESTERDAY. PREV DISCUSSION... /ISSUED 244 AM EDT THU OCT 18 2012/ DISCUSSION...LARGE SCALE MID LEVEL TROUGH IS CURRENTLY CENTERED OVER THE UPPER MISSISSIPPI VALLEY. A SHORT WAVE TROUGH EMBEDDED IN THIS FLOW MOVED ACROSS SOUTH FLORIDA WEDNESDAY AFTERNOON GENERATING SOME HEAVY THUNDERSTORMS ACROSS THE NORTHEAST PORTION OF THE REGION WITH ISOLATED LOCATIONS RECEIVING OVER FOUR INCHES OF RAINFALL. THIS TROUGH HAS LIFTED TO THE NORTHEAST WHILE AT THE SURFACE, A WEAK BOUNDARY IS LOCATED JUST OFF THE SOUTHEAST COAST. SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE BEING GENERATED ALONG THE BOUNDARY. ANOTHER WEAKER SHORT WAVE TROUGH IS LOCATED OVER THE CENTRAL GULF OF MEXICO WHICH IS SOMEWHAT EVIDENT ON WATER VAPOR IMAGERY. THE GFS, NAM AND ECMWF ALL DEPICT THIS FEATURE BUT THE NAM HAS A MORE PRONOUNCED TROUGH AND THUS YIELDS THE HIGHEST POPS. MUCH DRIER AIR ABOVE 10-15K FEET IS CURRENTLY MOVING INTO THE REGION BEHIND THE EXITING TROUGH. WHILE THERE WILL BE SOME INCREASE IN MOISTURE WITH THE SECONDARY TROUGH, IT WOULD APPEAR THE NAM IS SUFFERING ONCE AGAIN FROM MESOSCALE BIAS. THE TROUGH AXIS WILL CONTINUE THE SOUTHWEST STEERING FLOW ACROSS SOUTH FLORIDA SO ANYTHING THAT DEVELOPS OVER THE INTERIOR WILL MOVE AGAIN TOWARDS THE EAST COAST METRO AREA. THE RAPID REFRESH WHICH PERFORMED VERY WELL WITH YESTERDAY`S CONVECTION AND ITS CURRENT RUN GOES OUT THROUGH 18Z, SHOWS SOME DEVELOPMENT BEGINNING AROUND 17Z BUT DOES NOT GET TOO AGGRESSIVE. SO THAT BEING SAID HAVE LEANED CLOSER TO THE MAV NUMBERS WHICH IS QUITE A BIT LESS FROM THE MET GUIDANCE. ALL MODEL GUIDANCE NOW SHOWS THE MAIN TROUGH LIFTING TO THE NORTHEAST THROUGH SATURDAY AS A STRONG TROUGH DEVELOPS IN THE NORTH PACIFIC. THIS WILL ALLOW FOR THE DRIER AIR MASS TO FILTER DOWN ACROSS THE PENINSULA ON SATURDAY INTO EARLY NEXT WEEK WITH DEW POINTS ALSO DROPPING INTO THE 60S. SO A COUPLE MORE DAYS OF THE HIGHER HUMIDITY AND MORE PLEASANT CONDITIONS FOR THE WEEKEND AND AT LEAST EARLY NEXT WEEK. MARINE...TRANQUIL WIND AND SEAS ARE EXPECTED THROUGH THE REMAINDER OF THIS WEEK AND THEN ONLY A SLOW INCREASE IN THE SEAS OVER THE WEEKEND AND INTO NEXT WEEK AS THE WIND VEERS TO A MORE NORTH TO NORTHEAST DIRECTION. WIND SPEEDS ARE ANTICIPATED TO REMAIN AT 15 KNOTS OR LESS HOWEVER AND SEAS WILL REMAIN WELL BELOW ADVISORY CRITERIA. FIRE WEATHER...NO PROBLEMS OR CONCERNS IN THE SHORT TERM. THERE WILL BE SOME LOWER RELATIVE HUMIDITIES OVER THE WEEKEND BUT AT THIS TIME IT LOOKS LIKE THEY WILL REMAIN ABOVE 35 PERCENT. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 87 74 87 72 / 50 30 30 20 FORT LAUDERDALE 86 76 87 75 / 50 30 20 20 MIAMI 88 75 88 75 / 50 30 20 20 NAPLES 87 71 86 72 / 50 20 20 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...60/BD AVIATION/RADAR...57/DG
AREA FORECAST DISCUSSION
NWS MIAMI FL
724 AM EDT THU OCT 18 2012 .AVIATION...PLENTY OF LINGERING LOW-LEVEL MOISTURE AND CLOUD COVERAGE WITH BASES RANGING FROM 6-10 KFT WILL REMAIN IN PLACE THIS MORNING. SOME OF THE INTERIOR AREAS MAY EVEN EXPERIENCE BRIEF PERIODS WITH REDUCED VISIBILITIES IF ANY OF THIS CLOUD COVERAGE CLEARS...WITH THE BEST CHANCE INLAND AWAY FROM THE IMMEDIATE COAST. AS THE DAY PROGRESSES...PLENTY OF LOW-LEVEL MOISTURE UP TO 10-13 KFT COMBINED WITH WHAT IS LEFT OF AN OLD FRONTAL BOUNDARY WILL KEEP THE RAIN CHANCES IN THE FORECAST TODAY. THE LATEST WRF AND HRRR MODEL REFLECTIVITIES INDICATE MAINLY SCATTERED SHOWERS REMAINING POSSIBLE ONCE AGAIN THROUGH THE LATE MORNING AND AFTERNOON PERIODS. WESTERLY DEEP LAYER STEERING FLOW WILL FAVOR THE BEST SHOWER COVERAGE ACROSS THE INTERIOR AND EASTERN HALF OF THE PENINSULA...SIMILAR TO YESTERDAY. && .PREV DISCUSSION... /ISSUED 244 AM EDT THU OCT 18 2012/ DISCUSSION...LARGE SCALE MID LEVEL TROUGH IS CURRENTLY CENTERED OVER THE UPPER MISSISSIPPI VALLEY. A SHORT WAVE TROUGH EMBEDDED IN THIS FLOW MOVED ACROSS SOUTH FLORIDA WEDNESDAY AFTERNOON GENERATING SOME HEAVY THUNDERSTORMS ACROSS THE NORTHEAST PORTION OF THE REGION WITH ISOLATED LOCATIONS RECEIVING OVER FOUR INCHES OF RAINFALL. THIS TROUGH HAS LIFTED TO THE NORTHEAST WHILE AT THE SURFACE, A WEAK BOUNDARY IS LOCATED JUST OFF THE SOUTHEAST COAST. SCATTERED SHOWERS AND A FEW THUNDERSTORMS ARE BEING GENERATED ALONG THE BOUNDARY. ANOTHER WEAKER SHORT WAVE TROUGH IS LOCATED OVER THE CENTRAL GULF OF MEXICO WHICH IS SOMEWHAT EVIDENT ON WATER VAPOR IMAGERY. THE GFS, NAM AND ECMWF ALL DEPICT THIS FEATURE BUT THE NAM HAS A MORE PRONOUNCED TROUGH AND THUS YIELDS THE HIGHEST POPS. MUCH DRIER AIR ABOVE 10-15K FEET IS CURRENTLY MOVING INTO THE REGION BEHIND THE EXITING TROUGH. WHILE THERE WILL BE SOME INCREASE IN MOISTURE WITH THE SECONDARY TROUGH, IT WOULD APPEAR THE NAM IS SUFFERING ONCE AGAIN FROM MESOSCALE BIAS. THE TROUGH AXIS WILL CONTINUE THE SOUTHWEST STEERING FLOW ACROSS SOUTH FLORIDA SO ANYTHING THAT DEVELOPS OVER THE INTERIOR WILL MOVE AGAIN TOWARDS THE EAST COAST METRO AREA. THE RAPID REFRESH WHICH PERFORMED VERY WELL WITH YESTERDAY`S CONVECTION AND ITS CURRENT RUN GOES OUT THROUGH 18Z, SHOWS SOME DEVELOPMENT BEGINNING AROUND 17Z BUT DOES NOT GET TOO AGGRESSIVE. SO THAT BEING SAID HAVE LEANED CLOSER TO THE MAV NUMBERS WHICH IS QUITE A BIT LESS FROM THE MET GUIDANCE. ALL MODEL GUIDANCE NOW SHOWS THE MAIN TROUGH LIFTING TO THE NORTHEAST THROUGH SATURDAY AS A STRONG TROUGH DEVELOPS IN THE NORTH PACIFIC. THIS WILL ALLOW FOR THE DRIER AIR MASS TO FILTER DOWN ACROSS THE PENINSULA ON SATURDAY INTO EARLY NEXT WEEK WITH DEW POINTS ALSO DROPPING INTO THE 60S. SO A COUPLE MORE DAYS OF THE HIGHER HUMIDITY AND MORE PLEASANT CONDITIONS FOR THE WEEKEND AND AT LEAST EARLY NEXT WEEK. MARINE...TRANQUIL WIND AND SEAS ARE EXPECTED THROUGH THE REMAINDER OF THIS WEEK AND THEN ONLY A SLOW INCREASE IN THE SEAS OVER THE WEEKEND AND INTO NEXT WEEK AS THE WIND VEERS TO A MORE NORTH TO NORTHEAST DIRECTION. WIND SPEEDS ARE ANTICIPATED TO REMAIN AT 15 KNOTS OR LESS HOWEVER AND SEAS WILL REMAIN WELL BELOW ADVISORY CRITERIA. FIRE WEATHER...NO PROBLEMS OR CONCERNS IN THE SHORT TERM. THERE WILL BE SOME LOWER RELATIVE HUMIDITIES OVER THE WEEKEND BUT AT THIS TIME IT LOOKS LIKE THEY WILL REMAIN ABOVE 35 PERCENT. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 87 74 87 72 / 40 30 30 20 FORT LAUDERDALE 86 76 87 75 / 40 30 20 20 MIAMI 88 75 88 75 / 40 30 20 20 NAPLES 87 71 86 72 / 30 20 20 20 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION...UPDATE
NWS TAMPA BAY RUSKIN FL
550 AM EDT THU OCT 18 2012 .UPDATE... EXTENDED THE SLIGHT CHANCE POP FOR A FEW SHOWERS ALONG THE COAST NORTHWARD TO THE TAMPA BAY AREA AREA FOR THE MORNING HOURS. RADAR SHOWS A SHOWERS HAVE BEEN ABLE TO TAKE ADVANTAGE OF THE LAND BREEZE AND SOME SHALLOW MOISTURE BELOW 10KFT. A FEW OF THESE SHOWERS MAY MIGRATE BACK TO THE BEACHES DURING THE NEXT FEW HOURS BEFORE DAYTIME HEATING SHUTS DOWN THE LAND BREEZE CIRCULATION. && .SYNOPSIS... 08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN AMPLIFIED...AND STILL AMPLIFYING UPPER LEVEL PATTERN OVER THE CONUS. PATTERN IS HIGHLIGHTED BY A LONGWAVE TROUGH AND DEEP UPPER LOW OVER THE CENTRAL PORTION OF THE COUNTRY. THIS TROUGH/UPPER LOW WILL CONTINUE TO SHARPEN AND DIG SOUTHWARD AS IT MIGRATES OVER THE EASTERN STATES DURING THE NEXT 24 HOURS. CURRENTLY CLOSER TO HOME WE FIND OUR REGION STILL UNDER DEEP LAYER SYNOPTIC SUBSIDENCE IN THE WAKE OF THE SHORTWAVE THE BROUGHT THE CLOUDS AND SHOWERS TO THE REGION ON WEDNESDAY. THE UPPER FLOW OVERHEAD WILL BECOME INCREASINGLY CYCLONIC ONCE AGAIN LATER TODAY INTO FRIDAY AS WE COME UNDER THE INFLUENCE OF THE EASTERN U.S. TROUGH. AT THE SURFACE...FAIRLY WEAK GRADIENT IN PLACE ACROSS THE FORECAST AREA THIS MORNING BETWEEN A SUBTLE SURFACE TROUGH TOWARD THE KEYS/FL STRAITS...AND A WELL DEFINED COLD FRONT CROSSING THE TN/LOWER MS VALLEYS. THIS FRONT IS SUPPORTING A SQUALL LINE OF STRONG/SEVERE STORMS ALONG IT THIS MORNING. ALTHOUGH SOME SHOWERS ACTIVITY IS ANTICIPATED WITH THIS FRONT ONCE IT EVENTUALLY ARRIVES IN OUR AREA FRIDAY/FRIDAY NIGHT...SEVERE WEATHER IS NOT EXPECTED THIS FAR SOUTH. REGIONAL RADARS ALSO SHOW SOME SHOWER/STORM ACTIVITY DOWN TOWARD THE FL KEYS IN ASSOCIATED WITH THE FOCUS ALONG THE SURFACE TROUGH. && .SHORT TERM (TODAY THROUGH SATURDAY)... TODAY...LARGE SYNOPTIC TROUGH WILL CONTINUE TO BUILD EASTWARD AND ALONG THE NORTHERN GULF COAST. NOT GOING TO SEE MUCH INFLUENCE FROM THIS FEATURE DURING THE DAYLIGHT HOURS AS NO HEIGHT FALLS ARE FORECAST TO ARRIVE UNTIL TONIGHT/FRIDAY MORNING. THE LACK OF ANY SYNOPTIC FORCING AND GENERALLY DRY AIR ALOFT OVER THE MAJORITY OF THE AREA WILL HELP PROVIDE A DRY AND WARM FORECAST. THERE ARE SOME INDICATION THAT THE WEAK SURFACE TROUGH OVER SOUTH FLORIDA WILL SLOWLY MIGRATE NORTHWARD DURING THE DAY AND MAKE ENOUGH PROGRESS TO RESULT IN A FEW SHOWERS/STORMS AS FAR NORTH AS LEE/CHARLOTTE/DESOTO/HIGHLANDS COUNTIES BY THIS AFTERNOON. NOT ANTICIPATING A WHOLE LOT OF ACTIVITY AND WILL KEEP POPS 20-25%. ANY FURTHER NORTH AND RAIN CHANCES WILL BE 10% OR LESS. HIGH TEMPS REACH INTO THE MIDDLE/UPPER 80S FOR MOST AREAS. DEVELOPING FLOW OFF THE NOW RELATIVELY COOLER COASTAL WATERS SHOULD HELP KEEP THE IMMEDIATE COAST IN THE LOWER 80S (ESPECIALLY THE NATURE COAST). TONIGHT...SURFACE COLD FRONT WILL BE APPROACHING FROM THE NORTHWEST. GUIDANCE CONSENSUS SHOWS THE FRONT REACHING THE FL BIG BEND REGION BY SUNRISE FRIDAY MORNING. DUE TO A LACK OF AVAILABLE MOISTURE AND WEAK SYNOPTIC FORCING...WHATEVER SHOWERS THIS FRONT CONTAINS WILL BE PRIMARILY FORCED BY THE LOW LEVEL FOCUS AND CONFINED NEAR THE BOUNDARY. WITH THIS IN MIND WILL BRING IN SLIGHT CHANCE POPS FOR LEVY COUNTY IN THE PRE-DAWN HOURS. ONSHORE FLOW MAY ALSO PROVIDE A SLIGHT CHANCE FOR A SHOWER OR 2 DOWN TOWARD THE SUNCOAST...BUT THE OVERNIGHT WILL BE GENERALLY DRY FOR THESE ZONES. FRIDAY/FRIDAY NIGHT...UPPER TROUGH CONTINUES TO EVOLVE WITH SOME WEAK HEIGHT FALLS FINALLY ARRIVING. THE SURFACE FRONT WILL BE A SLOW MOVER AT THIS POINT AS IT AWAITS A FINAL SYNOPTIC PUSH LATE IN THE DAY/FRIDAY NIGHT. BEST CHANCES FOR SCT SHOWERS WITH THE FRONT WILL REMAIN NORTH OF TAMPA BAY...AND ESPECIALLY NORTH OF THE BROOKSVILLE AREA. ALTHOUGH THE BEST CHANCES FOR ANY ORGANIZED SHOWER ACTIVITY WILL BE FOR THESE NORTHERN ZONES...CAN NOT RULE OUT A FEW ISOLATED SHOWERS FOR THE REST OF FORECAST AREA EITHER UNDERNEATH A BROAD REGIME OF DEEP LAYER QG FORCING. A FINAL AND MORE DEFINED SHORTWAVE ROUNDING THE BASE OF THE MAIN TROUGH FRIDAY EVE/NIGHT WILL PROVIDE THE MASS FIELDS TO ACCELERATE THE FRONT SOUTHWARD. DESPITE BETTER SYNOPTIC/QG FORCING BY THIS TIME...MOISTURE WILL BE VERY LACKING AND ONLY SUPPORT SLIGHT CHANCE/ISOLATED SHOWER WORDING. GIVING SOME WEIGHT TO THE NAM/SREF WILL BEGIN TO END SHOWERS FROM NORTH TO SOUTH AFTER MIDNIGHT...HOWEVER IF THE GFS ENDS UP VERIFYING THEN THE DRYING PROCESS WILL BEGIN AND END EVEN FASTER. SATURDAY...SURFACE COLD FRONT QUICKLY EXITS TO OUR SOUTH EARLY IN THE MORNING. KEEPING A SLIGHT CHANCE POP IN THE GRIDS SOUTH OF THE I-4 CORRIDOR THROUGH MID-MORNING...HOWEVER AS MENTIONED ABOVE... THESE SHOWERS MAY VERY WELL NEED TO BE REMOVED WITH FUTURE FORECASTS. HIGH PRESSURE WILL QUICKLY BUILD IN FROM THE WEST AND PROVIDE A GENERALLY DRY AND SEASONABLE DAY UNDER MOSTLY TO PARTLY SUNNY SKIES. AFTERNOON HIGH TEMPS WILL RANGE FROM THE LOWER 80S NORTH TO THE MID 80S SOUTH. && .LONG TERM (SATURDAY NIGHT THROUGH NEXT WEDNESDAY)... HIGH PRESSURE BEHIND THE COLD FRONT WILL BE DUE NORTH OF THE REGION SATURDAY NIGHT WITH A NORTHERLY DRAINAGE FLOW EXPECTED SUNDAY MORNING. WITH CLEAR SKIES OVERHEAD...EXPECT FAIRLY GOOD RADIATIONAL COOLING WHICH WILL ALLOW TEMPERATURES TO FALL TO NEAR 50 DEGREES OVER THE NATURE COAST...AND INTO THE 50S TO NEAR 60 FOR THE REST OF THE REGION AWAY FROM THE COAST. SUNDAY THROUGH WEDNESDAY WILL FEATURE A SLOW WARMING TREND AS SURFACE HIGH PRESSURE SETTLES IN TO THE NORTH OF THE AREA WHILE AN UPPER-LEVEL RIDGE BUILDS FROM THE WESTERN GULF...NORTHEASTWARD TOWARD THE SOUTHEASTERN STATES. WHILE WE CAN NOT REALLY RULE OUT A SHOWER OR TWO AT TIMES...THE ATMOSPHERE LOOKS VERY DRY AND WILL LEAVE OUT ANY MENTION OF PRECIPITATION AT THIS TIME. TEMPERATURES WILL START OFF NEAR NORMAL ON SUNDAY...THEN BEGIN TO RUN A COUPLE DEGREES ABOVE NORMAL AGAIN FOR THE FIRST HALF OF THE NEXT WORK WEEK. && .AVIATION... SOME PATCHY FOG POSSIBLE TOWARD SUNRISE MAINLY AROUND PGD AND LAL. OTHERWISE...VFR CONDITIONS NEXT 24 HOURS. && .MARINE... A WEAK GRADIENT WILL KEEP WINDS AND SEAS LOW OVER THE EASTERN GULF TODAY. A COLD FRONT WILL APPROACH AND MOVE INTO THE NORTHERN MARINE ZONES FRIDAY BEFORE QUICKLY MOVING SOUTH OF THE REGION FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL BUILD NORTH OF THE FORECAST WATERS IN THE WAKE OF THIS FRONT AND LEAD TO PERIODS OF CAUTIONARY LEVEL EASTERLY WINDS BY LATER SUNDAY INTO THE EARLY PORTION OF NEXT WEEK. && .FIRE WEATHER... A COLD FRONT WILL APPROACH THE REGION TODAY AND TONIGHT AND THEN MOVE THROUGH THE FLORIDA PENINSULA BY EARLY SATURDAY. DRIER AIR WILL ARRIVE IN THE WAKE OF THIS FRONT FOR SATURDAY AFTERNOON. THERE IS STILL SOME UNCERTAINTY IN THE DEGREE OF DRY AIR FOR SATURDAY... ESPECIALLY SOUTH OF THE I-4 CORRIDOR...HOWEVER A PERIOD OF CRITICALLY LOW RELATIVE HUMIDITY IS LIKELY NORTH OF I-4 WITH NEAR CRITICAL LEVELS OF RELATIVE HUMIDITY FURTHER SOUTH. DISPERSION INDICES ARE ALSO CURRENTLY FORECAST TO BE NEAR 75 TO THE NORTH OF TAMPA BAY SATURDAY AFTERNOON. IF THIS TREND CONTINUES...THEN FIRE WEATHER WATCHES MAY BECOME NECESSARY. && .PRELIMINARY POINT TEMPS/POPS... TPA 85 70 86 68 / 10 10 10 20 FMY 88 71 88 71 / 30 20 20 20 GIF 89 67 88 64 / 10 10 20 20 SRQ 85 70 85 68 / 10 10 10 20 BKV 88 64 86 63 / 10 10 20 20 SPG 85 72 84 72 / 10 10 10 20 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WEATHER...MROCZKA LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
410 AM EDT THU OCT 18 2012 .SYNOPSIS... 08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN AMPLIFIED...AND STILL AMPLIFYING UPPER LEVEL PATTERN OVER THE CONUS. PATTERN IS HIGHLIGHTED BY A LONGWAVE TROUGH AND DEEP UPPER LOW OVER THE CENTRAL PORTION OF THE COUNTRY. THIS TROUGH/UPPER LOW WILL CONTINUE TO SHARPEN AND DIG SOUTHWARD AS IT MIGRATES OVER THE EASTERN STATES DURING THE NEXT 24 HOURS. CURRENTLY CLOSER TO HOME WE FIND OUR REGION STILL UNDER DEEP LAYER SYNOPTIC SUBSIDENCE IN THE WAKE OF THE SHORTWAVE THE BROUGHT THE CLOUDS AND SHOWERS TO THE REGION ON WEDNESDAY. THE UPPER FLOW OVERHEAD WILL BECOME INCREASINGLY CYCLONIC ONCE AGAIN LATER TODAY INTO FRIDAY AS WE COME UNDER THE INFLUENCE OF THE EASTERN U.S. TROUGH. AT THE SURFACE...FAIRLY WEAK GRADIENT IN PLACE ACROSS THE FORECAST AREA THIS MORNING BETWEEN A SUBTLE SURFACE TROUGH TOWARD THE KEYS/FL STRAITS...AND A WELL DEFINED COLD FRONT CROSSING THE TN/LOWER MS VALLEYS. THIS FRONT IS SUPPORTING A SQUALL LINE OF STRONG/SEVERE STORMS ALONG IT THIS MORNING. ALTHOUGH SOME SHOWERS ACTIVITY IS ANTICIPATED WITH THIS FRONT ONCE IT EVENTUALLY ARRIVES IN OUR AREA FRIDAY/FRIDAY NIGHT...SEVERE WEATHER IS NOT EXPECTED THIS FAR SOUTH. REGIONAL RADARS ALSO SHOW SOME SHOWER/STORM ACTIVITY DOWN TOWARD THE FL KEYS IN ASSOCIATED WITH THE FOCUS ALONG THE SURFACE TROUGH. && .SHORT TERM (TODAY THROUGH SATURDAY)... TODAY...LARGE SYNOPTIC TROUGH WILL CONTINUE TO BUILD EASTWARD AND ALONG THE NORTHERN GULF COAST. NOT GOING TO SEE MUCH INFLUENCE FROM THIS FEATURE DURING THE DAYLIGHT HOURS AS NO HEIGHT FALLS ARE FORECAST TO ARRIVE UNTIL TONIGHT/FRIDAY MORNING. THE LACK OF ANY SYNOPTIC FORCING AND GENERALLY DRY AIR ALOFT OVER THE MAJORITY OF THE AREA WILL HELP PROVIDE A DRY AND WARM FORECAST. THERE ARE SOME INDICATION THAT THE WEAK SURFACE TROUGH OVER SOUTH FLORIDA WILL SLOWLY MIGRATE NORTHWARD DURING THE DAY AND MAKE ENOUGH PROGRESS TO RESULT IN A FEW SHOWERS/STORMS AS FAR NORTH AS LEE/CHARLOTTE/DESOTO/HIGHLANDS COUNTIES BY THIS AFTERNOON. NOT ANTICIPATING A WHOLE LOT OF ACTIVITY AND WILL KEEP POPS 20-25%. ANY FURTHER NORTH AND RAIN CHANCES WILL BE 10% OR LESS. HIGH TEMPS REACH INTO THE MIDDLE/UPPER 80S FOR MOST AREAS. DEVELOPING FLOW OFF THE NOW RELATIVELY COOLER COASTAL WATERS SHOULD HELP KEEP THE IMMEDIATE COAST IN THE LOWER 80S (ESPECIALLY THE NATURE COAST). TONIGHT...SURFACE COLD FRONT WILL BE APPROACHING FROM THE NORTHWEST. GUIDANCE CONSENSUS SHOWS THE FRONT REACHING THE FL BIG BEND REGION BY SUNRISE FRIDAY MORNING. DUE TO A LACK OF AVAILABLE MOISTURE AND WEAK SYNOPTIC FORCING...WHATEVER SHOWERS THIS FRONT CONTAINS WILL BE PRIMARILY FORCED BY THE LOW LEVEL FOCUS AND CONFINED NEAR THE BOUNDARY. WITH THIS IN MIND WILL BRING IN SLIGHT CHANCE POPS FOR LEVY COUNTY IN THE PRE-DAWN HOURS. ONSHORE FLOW MAY ALSO PROVIDE A SLIGHT CHANCE FOR A SHOWER OR 2 DOWN TOWARD THE SUNCOAST...BUT THE OVERNIGHT WILL BE GENERALLY DRY FOR THESE ZONES. FRIDAY/FRIDAY NIGHT...UPPER TROUGH CONTINUES TO EVOLVE WITH SOME WEAK HEIGHT FALLS FINALLY ARRIVING. THE SURFACE FRONT WILL BE A SLOW MOVER AT THIS POINT AS IT AWAITS A FINAL SYNOPTIC PUSH LATE IN THE DAY/FRIDAY NIGHT. BEST CHANCES FOR SCT SHOWERS WITH THE FRONT WILL REMAIN NORTH OF TAMPA BAY...AND ESPECIALLY NORTH OF THE BROOKSVILLE AREA. ALTHOUGH THE BEST CHANCES FOR ANY ORGANIZED SHOWER ACTIVITY WILL BE FOR THESE NORTHERN ZONES...CAN NOT RULE OUT A FEW ISOLATED SHOWERS FOR THE REST OF FORECAST AREA EITHER UNDERNEATH A BROAD REGIME OF DEEP LAYER QG FORCING. A FINAL AND MORE DEFINED SHORTWAVE ROUNDING THE BASE OF THE MAIN TROUGH FRIDAY EVE/NIGHT WILL PROVIDE THE MASS FIELDS TO ACCELERATE THE FRONT SOUTHWARD. DESPITE BETTER SYNOPTIC/QG FORCING BY THIS TIME...MOISTURE WILL BE VERY LACKING AND ONLY SUPPORT SLIGHT CHANCE/ISOLATED SHOWER WORDING. GIVING SOME WEIGHT TO THE NAM/SREF WILL BEGIN TO END SHOWERS FROM NORTH TO SOUTH AFTER MIDNIGHT...HOWEVER IF THE GFS ENDS UP VERIFYING THEN THE DRYING PROCESS WILL BEGIN AND END EVEN FASTER. SATURDAY...SURFACE COLD FRONT QUICKLY EXITS TO OUR SOUTH EARLY IN THE MORNING. KEEPING A SLIGHT CHANCE POP IN THE GRIDS SOUTH OF THE I-4 CORRIDOR THROUGH MID-MORNING...HOWEVER AS MENTIONED ABOVE... THESE SHOWERS MAY VERY WELL NEED TO BE REMOVED WITH FUTURE FORECASTS. HIGH PRESSURE WILL QUICKLY BUILD IN FROM THE WEST AND PROVIDE A GENERALLY DRY AND SEASONABLE DAY UNDER MOSTLY TO PARTLY SUNNY SKIES. AFTERNOON HIGH TEMPS WILL RANGE FROM THE LOWER 80S NORTH TO THE MID 80S SOUTH. && .LONG TERM (SATURDAY NIGHT THROUGH NEXT WEDNESDAY)... HIGH PRESSURE BEHIND THE COLD FRONT WILL BE DUE NORTH OF THE REGION SATURDAY NIGHT WITH A NORTHERLY DRAINAGE FLOW EXPECTED SUNDAY MORNING. WITH CLEAR SKIES OVERHEAD...EXPECT FAIRLY GOOD RADIATIONAL COOLING WHICH WILL ALLOW TEMPERATURES TO FALL TO NEAR 50 DEGREES OVER THE NATURE COAST...AND INTO THE 50S TO NEAR 60 FOR THE REST OF THE REGION AWAY FROM THE COAST. SUNDAY THROUGH WEDNESDAY WILL FEATURE A SLOW WARMING TREND AS SURFACE HIGH PRESSURE SETTLES IN TO THE NORTH OF THE AREA WHILE AN UPPER-LEVEL RIDGE BUILDS FROM THE WESTERN GULF...NORTHEASTWARD TOWARD THE SOUTHEASTERN STATES. WHILE WE CAN NOT REALLY RULE OUT A SHOWER OR TWO AT TIMES...THE ATMOSPHERE LOOKS VERY DRY AND WILL LEAVE OUT ANY MENTION OF PRECIPITATION AT THIS TIME. TEMPERATURES WILL START OFF NEAR NORMAL ON SUNDAY...THEN BEGIN TO RUN A COUPLE DEGREES ABOVE NORMAL AGAIN FOR THE FIRST HALF OF THE NEXT WORK WEEK. && .AVIATION... SOME PATCHY FOG POSSIBLE TOWARD SUNRISE MAINLY AROUND PGD AND LAL. OTHERWISE...VFR CONDITIONS NEXT 24 HOURS. && .MARINE... A WEAK GRADIENT WILL KEEP WINDS AND SEAS LOW OVER THE EASTERN GULF TODAY. A COLD FRONT WILL APPROACH AND MOVE INTO THE NORTHERN MARINE ZONES FRIDAY BEFORE QUICKLY MOVING SOUTH OF THE REGION FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL BUILD NORTH OF THE FORECAST WATERS IN THE WAKE OF THIS FRONT AND LEAD TO PERIODS OF CAUTIONARY LEVEL EASTERLY WINDS BY LATER SUNDAY INTO THE EARLY PORTION OF NEXT WEEK. && .FIRE WEATHER... A COLD FRONT WILL APPROACH THE REGION TODAY AND TONIGHT AND THEN MOVE THROUGH THE FLORIDA PENINSULA BY EARLY SATURDAY. DRIER AIR WILL ARRIVE IN THE WAKE OF THIS FRONT FOR SATURDAY AFTERNOON. THERE IS STILL SOME UNCERTAINTY IN THE DEGREE OF DRY AIR FOR SATURDAY... ESPECIALLY SOUTH OF THE I-4 CORRIDOR...HOWEVER A PERIOD OF CRITICALLY LOW RELATIVE HUMIDITY IS LIKELY NORTH OF I-4 WITH NEAR CRITICAL LEVELS OF RELATIVE HUMIDITY FURTHER SOUTH. DISPERSION INDICES ARE ALSO CURRENTLY FORECAST TO BE NEAR 75 TO THE NORTH OF TAMPA BAY SATURDAY AFTERNOON. IF THIS TREND CONTINUES...THEN FIRE WEATHER WATCHES MAY BECOME NECESSARY. && .PRELIMINARY POINT TEMPS/POPS... TPA 85 70 86 68 / 10 10 10 20 FMY 88 71 88 71 / 30 20 20 20 GIF 89 67 88 64 / 10 10 20 20 SRQ 85 70 85 68 / 10 10 10 20 BKV 88 64 86 63 / 10 10 20 20 SPG 85 72 84 72 / 10 10 10 20 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WEATHER...MROCZKA LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION...RESENT
NWS TAMPA BAY RUSKIN FL
355 AM EDT THU OCT 18 2012 .SYNOPSIS... 07Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN AMPLIFIED...AND STILL AMPLIFYING UPPER LEVEL PATTERN OVER THE CONUS. PATTERN IS HIGHLIGHTED BY A LONGWAVE TROUGH AND DEEP UPPER LOW OVER THE CENTRAL PORTION OF THE COUNTRY. THIS TROUGH/UPPER LOW WILL CONTINUE TO SHARPEN AND DIG SOUTHWARD AS IT MIGRATES OVER THE EASTERN STATES DURING THE NEXT 24 HOURS. CURRENTLY CLOSER TO HOME WE FIND OUR REGION STILL UNDER DEEP LAYER SYNOPTIC SUBSIDENCE IN THE WAKE OF THE SHORTWAVE THE BROUGHT THE CLOUDS AND SHOWERS TO THE REGION ON WEDNESDAY. THE UPPER FLOW OVERHEAD WILL BECOME INCREASINGLY CYCLONIC ONCE AGAIN LATER TODAY INTO FRIDAY AS WE COME UNDER THE INFLUENCE OF THE EASTERN U.S. TROUGH. AT THE SURFACE...FAIRLY WEAK GRADIENT IN PLACE ACROSS THE FORECAST AREA THIS MORNING BETWEEN A SUBTLE SURFACE TROUGH TOWARD THE KEYS/FL STRAITS...AND A WELL DEFINED COLD FRONT CROSSING THE TN/LOWER MS VALLEYS. THIS FRONT IS SUPPORTING A SQUALL LINE OF STRONG/SEVERE STORMS ALONG IT THIS MORNING. ALTHOUGH SOME SHOWERS ACTIVITY IS ANTICIPATED WITH THIS FRONT ONCE IT EVENTUALLY ARRIVES IN OUR AREA FRIDAY/FRIDAY NIGHT...SEVERE WEATHER IS NOT EXPECTED THIS FAR SOUTH. REGIONAL RADARS ALSO SHOW SOME SHOWER/STORM ACTIVITY DOWN TOWARD THE FL KEYS IN ASSOCIATED WITH THE FOCUS ALONG THE SURFACE TROUGH. && .SHORT TERM (TODAY THROUGH SATURDAY)... TODAY...LARGE SYNOPTIC TROUGH WILL CONTINUE TO BUILD EASTWARD AND ALONG THE NORTHERN GULF COAST. NOT GOING TO SEE MUCH INFLUENCE FROM THIS FEATURE DURING THE DAYLIGHT HOURS AS NO HEIGHT FALLS ARE FORECAST TO ARRIVE UNTIL TONIGHT/FRIDAY MORNING. THE LACK OF ANY SYNOPTIC FORCING AND GENERALLY DRY AIR ALOFT OVER THE MAJORITY OF THE AREA WILL HELP PROVIDE A DRY AND WARM FORECAST. THERE ARE SOME INDICATION THAT THE WEAK SURFACE TROUGH OVER SOUTH FLORIDA WILL SLOWLY MIGRATE NORTHWARD DURING THE DAY AND MAKE ENOUGH PROGRESS TO RESULT IN A FEW SHOWERS/STORMS AS FAR NORTH AS LEE/CHARLOTTE/DESOTO/HIGHLANDS COUNTIES BY THIS AFTERNOON. NOT ANTICIPATING A WHOLE LOT OF ACTIVITY AND WILL KEEP POPS 20-25%. ANY FURTHER NORTH AND RAIN CHANCES WILL BE 10% OR LESS. HIGH TEMPS REACH INTO THE MIDDLE/UPPER 80S FOR MOST AREAS. DEVELOPING FLOW OFF THE NOW RELATIVELY COOLER COASTAL WATERS SHOULD HELP KEEP THE IMMEDIATE COAST IN THE LOWER 80S (ESPECIALLY THE NATURE COAST). TONIGHT...SURFACE COLD FRONT WILL BE APPROACHING FROM THE NORTHWEST. GUIDANCE CONSENSUS SHOWS THE FRONT REACHING THE FL BIG BEND REGION BY SUNRISE FRIDAY MORNING. DUE TO A LACK OF AVAILABLE MOISTURE AND WEAK SYNOPTIC FORCING...WHATEVER SHOWERS THIS FRONT CONTAINS WILL BE PRIMARILY FORCED BY THE LOW LEVEL FOCUS AND CONFINED NEAR THE BOUNDARY. WITH THIS IN MIND WILL BRING IN SLIGHT CHANCE POPS FOR LEVY COUNTY IN THE PRE-DAWN HOURS. ONSHORE FLOW MAY ALSO PROVIDE A SLIGHT CHANCE FOR A SHOWER OR 2 DOWN TOWARD THE SUNCOAST...BUT THE OVERNIGHT WILL BE GENERALLY DRY FOR THESE ZONES. FRIDAY/FRIDAY NIGHT...UPPER TROUGH CONTINUES TO EVOLVE WITH SOME WEAK HEIGHT FALLS FINALLY ARRIVING. THE SURFACE FRONT WILL BE A SLOW MOVER AT THIS POINT AS IT AWAITS A FINAL SYNOPTIC PUSH LATE IN THE DAY/FRIDAY NIGHT. BEST CHANCES FOR SCT SHOWERS WITH THE FRONT WILL REMAIN NORTH OF TAMPA BAY...AND ESPECIALLY NORTH OF THE BROOKSVILLE AREA. ALTHOUGH THE BEST CHANCES FOR ANY ORGANIZED SHOWER ACTIVITY WILL BE FOR THESE NORTHERN ZONES...CAN NOT RULE OUT A FEW ISOLATED SHOWERS FOR THE REST OF FORECAST AREA EITHER UNDERNEATH A BROAD REGIME OF DEEP LAYER QG FORCING. A FINAL AND MORE DEFINED SHORTWAVE ROUNDING THE BASE OF THE MAIN TROUGH FRIDAY EVE/NIGHT WILL PROVIDE THE MASS FIELDS TO ACCELERATE THE FRONT SOUTHWARD. DESPITE BETTER SYNOPTIC/QG FORCING BY THIS TIME...MOISTURE WILL BE VERY LACKING AND ONLY SUPPORT SLIGHT CHANCE/ISOLATED SHOWER WORDING. GIVING SOME WEIGHT TO THE NAM/SREF WILL BEGIN TO END SHOWERS FROM NORTH TO SOUTH AFTER MIDNIGHT...HOWEVER IF THE GFS ENDS UP VERIFYING THEN THE DRYING PROCESS WILL BEGIN AND END EVEN FASTER. SATURDAY...SURFACE COLD FRONT QUICKLY EXITS TO OUR SOUTH EARLY IN THE MORNING. KEEPING A SLIGHT CHANCE POP IN THE GRIDS SOUTH OF THE I-4 CORRIDOR THROUGH MID-MORNING...HOWEVER AS MENTIONED ABOVE... THESE SHOWERS MAY VERY WELL NEED TO BE REMOVED WITH FUTURE FORECASTS. HIGH PRESSURE WILL QUICKLY BUILD IN FROM THE WEST AND PROVIDE A GENERALLY DRY AND SEASONABLE DAY UNDER MOSTLY TO PARTLY SUNNY SKIES. AFTERNOON HIGH TEMPS WILL RANGE FROM THE LOWER 80S NORTH TO THE MID 80S SOUTH. && .LONG TERM (SATURDAY NIGHT THROUGH NEXT WEDNESDAY)... HIGH PRESSURE BEHIND THE COLD FRONT WILL BE DUE NORTH OF THE REGION SATURDAY NIGHT WITH A NORTHERLY DRAINAGE FLOW EXPECTED SUNDAY MORNING. WITH CLEAR SKIES OVERHEAD...EXPECT FAIRLY GOOD RADIATIONAL COOLING WHICH WILL ALLOW TEMPERATURES TO FALL TO NEAR 50 DEGREES OVER THE NATURE COAST...AND INTO THE 50S TO NEAR 60 FOR THE REST OF THE REGION AWAY FROM THE COAST. SUNDAY THROUGH WEDNESDAY WILL FEATURE A SLOW WARMING TREND AS SURFACE HIGH PRESSURE SETTLES IN TO THE NORTH OF THE AREA WHILE AN UPPER-LEVEL RIDGE BUILDS FROM THE WESTERN GULF...NORTHEASTWARD TOWARD THE SOUTHEASTERN STATES. WHILE WE CAN NOT REALLY RULE OUT A SHOWER OR TWO AT TIMES...THE ATMOSPHERE LOOKS VERY DRY AND WILL LEAVE OUT ANY MENTION OF PRECIPITATION AT THIS TIME. TEMPERATURES WILL START OFF NEAR NORMAL ON SUNDAY...THEN BEGIN TO RUN A COUPLE DEGREES ABOVE NORMAL AGAIN FOR THE FIRST HALF OF THE NEXT WORK WEEK. && .AVIATION... SOME PATCHY FOG POSSIBLE TOWARD SUNRISE MAINLY AROUND PGD AND LAL. OTHERWISE...VFR CONDITIONS NEXT 24 HOURS. && .MARINE... A WEAK GRADIENT WILL KEEP WINDS AND SEAS LOW OVER THE EASTERN GULF TODAY. A COLD FRONT WILL APPROACH AND MOVE INTO THE NORTHERN MARINE ZONES FRIDAY BEFORE QUICKLY MOVING SOUTH OF THE REGION FRIDAY NIGHT AND EARLY SATURDAY. HIGH PRESSURE WILL BUILD NORTH OF THE FORECAST WATERS IN THE WAKE OF THIS FRONT AND LEAD TO PERIODS OF CAUTIONARY LEVEL EASTERLY WINDS BY LATER SUNDAY INTO THE EARLY PORTION OF NEXT WEEK. && .FIRE WEATHER... A COLD FRONT WILL APPROACH THE REGION TODAY AND TONIGHT AND THEN MOVE THROUGH THE FLORIDA PENINSULA BY EARLY SATURDAY. DRIER AIR WILL ARRIVE IN THE WAKE OF THIS FRONT FOR SATURDAY AFTERNOON. THERE IS STILL SOME UNCERTAINTY IN THE DEGREE OF DRY AIR FOR SATURDAY... ESPECIALLY SOUTH OF THE I-4 CORRIDOR...HOWEVER A PERIOD OF CRITICALLY LOW RELATIVE HUMIDITY IS LIKELY NORTH OF I-4 WITH NEAR CRITICAL LEVELS OF RELATIVE HUMIDITY FURTHER SOUTH. DISPERSION INDICES ARE ALSO CURRENTLY FORECAST TO BE NEAR 75 TO THE NORTH OF TAMPA BAY SATURDAY AFTERNOON. IF THIS TREND CONTINUES...THEN FIRE WEATHER WATCHES MAY BECOME NECESSARY. && .PRELIMINARY POINT TEMPS/POPS... TPA 85 70 86 68 / 10 10 10 20 FMY 88 71 88 71 / 30 20 20 20 GIF 89 67 88 64 / 10 10 20 20 SRQ 85 70 85 68 / 10 10 10 20 BKV 88 64 86 63 / 10 10 20 20 SPG 85 72 84 72 / 10 10 10 20 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WEATHER...MROCZKA LONG TERM/AVIATION...JILLSON
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
338 AM EDT THU OCT 18 2012 .DISCUSSION... TODAY-TONIGHT...ATLC RIDGE AXIS OVER THE FL STRAITS/NRN BAHAMAS WILL INTERACT WITH A FRONTAL TROF PUSHING THRU THE DEEP SOUTH TO GENERATE A STEADY S/SWRLY FLOW THRU THE H100-H70 LYR. EVENING SOUNDINGS SHOW THE AIRMASS HAS MOISTENED SIGNIFICANTLY OVER THE PAST 24HRS WITH PWAT VALUES RECOVERING TO 1.3" AT KJAX...1.5" AT KTBW...AND 2.0" AT KMFL...THANKS LARGELY TO THE DEEP LOW LVL SRLY FLOW...THE USAF 915HZ PROFILER AT THE CAPE INDICATING 15-20KTS THRU THE H100-H85 LYR. LATEST RAP ANALYSIS SHOWS A WEAK MID LVL VORT AXIS AND AN AREA OF DECENT UPR LVL DIVERGENCE ACRS THE S PENINSULA. BOTH ARE EMBEDDED WITHIN A STRONG ZONAL FLOW PATTERN THAT WILL TAKE THE BULK OF ITS LIFTING INFLUENCE OFFSHORE RATHER THAN NWD INTO CENTRAL FL. HOWEVER...ISENTROPIC ANALYSIS DOES SHOW STRONG LIFT THRU THE 310K-315K LYR AS THE ZONAL FLOW BLOWS ACRS A BAND OF ENHANCED H85-H70 THETA-E AIR...LIKELY THE REMNANTS OF THE WED FROPA. LOW LVL MOISTURE OVER THE STRAITS AND THE NW CARIB IS PLENTIFUL AND WILL LIFT NWD UNDER THE INFLUENCE OF THE SRLY LOW/MID LVL FLOW. THERMODYNAMIC PROFILE REVEALS H85-H70 LAPSE RATES BTWN 5.5-6.5C/KM OVER MUCH OF ECFL...BUT THESE FLATTEN OUT TO AOB 5.0C/KM THRU THE H85-H50 LYR. H50 TEMPS ARND -6C EXTEND ACRS MOST OF THE GOMEX. CANNOT COMPLETELY RULE TSRAS OUT OF THE FCST DUE TO THE LOW LVL MOISTURE AND THE ISENTROPIC LIFT...BUT THESE WILL BE LIMITED TO THE SERN CWA AS THE KJAX/KTAE SOUNDINGS INDICATE A SURPRISINGLY STRONG SUBSIDENCE INVERSION THRU THE H70-H50 LYR THAT WILL LIMIT VERTICAL MOTION ACRS THE NWRN CWA. LOW STRATUS CLOUDS OVER THE INTERIOR SHOULD BURN OFF RAPIDLY AFT SUNRISE. NEAR FULL SUN AND S/SW FLOW WILL ALLOW MAX TEMPS TO WARM INTO THE M/U80S. WINDS WILL DIMINISH AFT SUNSET BUT ARE NOT EXPECTED TO DECOUPLE DUE TO THE APPROACHING. LIGHT BUT STEADY S/SW WINDS WILL KEEP MIN TEMPS IN THE M/U60S INTERIOR...U60S/L70S ALONG THE COAST. FRI-SAT...LARGE LOW PRESSURE SYSTEM CENTERED OVER LAKE MICHIGAN REGION EARLY FRIDAY WILL LIFT NEWD INTO SATURDAY. COLD FRONT TRAILING FROM THIS SYSTEM WILL PUSH THROUGH THE CENTRAL FLORIDA PENINSULA FRIDAY NIGHT AND BE SOUTH OF THE AREA BY EARLY SATURDAY. SUFFICIENT MOISTURE AND DAYTIME INSTABILITY AHEAD OF THE FRONT FOR CHC/SCT SHRA AND ISOLD TSRA DAYTIME FRI WITH SOME ACTIVITY LINGERING INTO OVERNIGHT HOURS AHEAD OF THE FRONTAL PASSAGE. HIGH PRESSURE BUILDING IN BEHIND THE BOUNDARY WILL BRING AN END TO THE RAIN CHANCES AS A SLIGHTLY COOLER AND LESS HUMID AIR MASS MOVES IN FOR SATURDAY. EXPECT DAYTIME HIGHS IN THE MID/UPPER 80S FRI...THEN LOWER/MID 80S SATURDAY WITH LOWER DEW POINTS MAKING IT FEEL MORE COMFORTABLE AS WELL. MORN LOWS IN THE MID 60S NORTH/NEAR 70 SOUTH FRI AND NEAR 60/LOWER 60S NORTH AND MID/UPPER 60S SOUTH SAT. SUN-THU...SURFACE HIGH PRESSURE TO THE NORTH BUILDING ALONG THE EASTERN SEABOARD AND RIDGE ALOFT BUILDING ACROSS THE STATE FROM THE GULF OF MEXICO INTO EARLY NEXT WEEK. THIS WILL BRING AN ONSHORE FLOW REGIME TO EC FL WHICH IS EXPECTED TO PERSIST THROUGH THE MIDDLE OF THE WEEK. PATTERN WILL FAVOR A SLOW INCREASE IN MOISTURE AND TEMPS MODERATED BY THE ONSHORE FLOW. WILL KEEP POPS BELOW MENTIONABLE VALUES OVER LAND AREAS BUT SOME LOW POPS FOR COASTAL SHOWERS MAY BECOME WARRANTED. && .AVIATION...THRU 18/13Z...AREAS MVFR VSBYS/IFR CIGS N OF KISM-KTIX DUE TO BR AND LOW STRATUS. BTWN 18/13Z-18/18Z...VFR. BTWN 18/18Z-18-20Z...SFC WNDSHFT COASTAL SITES FM SW TO E/SE AOB 10KT ASSOCD WITH THE EAST COAST SEA BREEZE...VCSH S OF KMLB. BTWN 18/20Z-18/23Z...SFC WNDSHFT INTERIOR SITES FM SW TO S/SE AOB 10KTS AS THE EAST COAST SEA BREEZE PUSHES INLAND...CHC MVFR SHRAS/SLGT CHC IFR TSRAS S OF KMLB. BTWN 18/23Z-19/04Z...SLGT CHC MVFR SHRAS S OF KISM-KTIX. AFT 19/04Z...VFR. && .MARINE...TODAY-TONIGHT...LCL DATA BUOY/C-MAN NETWORK SHOWING SERLY SFC/BNDRY LYR BREEZE BTWN 15-20KTS N OF CAPE CANAVERAL...10-15KTS S OF THE CAPE. WINDS WILL DIMINISH TO AOB 10KTS BY AFTN AS A NEW FRONTAL TROF PUSHES ACRS THE DEEP SOUTH AND INTO THE FL PANHANDLE. LINGERING SWELLS FROM FORMER T.C. RAFAEL WILL SUBSIDE AS WELL. SEAS 3-4FT NEARSHORE AND 4-5FT OFFSHORE THRU SUNSET...BCMG 2-4FT AREAWIDE OVERNIGHT. SLGT CHC OF TSRAS MOVG OFFSHORE S OF KMLB THIS AFTN. WINDS WILL PICK UP OUT OF THE NNW-N FRI NIGHT INTO SAT AS FRONT PUSHES DOWN THE PENINSULA AND THE ADJACENT ATLANTIC WATERS. ONSHORE FLOW REGIME DEVELOPING BEHIND THE FRONT SUNDAY THROUGH THE MIDDLE OF NEXT WEEK WITH HIGH PRESSURE TO THE NORTH BUILDING ALONG THE EASTERN SEABOARD. THE ONSHORE WINDS INCREASING INTO THE 15-20KT RANGE AND PERSISTENT ONSHORE FLOW WILL RESULT IN SEA HEIGHTS RISING TO 6-7 FT OFFSHORE BY THE END OF THE PERIOD. && .PRELIMINARY POINT TEMPS/POPS... DAB 86 69 85 63 / 10 10 20 20 MCO 88 69 87 66 / 10 10 20 20 MLB 87 71 86 69 / 20 20 30 20 VRB 87 71 87 69 / 30 20 30 30 LEE 87 68 87 64 / 10 10 20 20 SFB 87 68 88 65 / 10 10 20 20 ORL 88 69 88 66 / 10 10 20 20 FPR 87 71 86 69 / 30 20 30 30 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM/AVIATION...BRAGAW LONG TERM....GLITTO
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
205 PM EDT THU OCT 18 2012 .PREV DISCUSSION... /ISSUED 330 AM EDT THU OCT 18 2012/ SHORT TERM /TODAY THROUGH FRIDAY/... NAM/GFS/ECMWF IN DECENT AGREEMENT THROUGH THE SHORT TERM...SO WENT WITH A GENERAL BLEND FOR MOST ELEMENTS. LARGE MID LEVEL LOW SPINNING OVER THE US/CANADA BORDER CONTINUES TO DEEPEN AND PROPAGATE SOUTHEAST /500MB 00Z UA ANALYSIS HAD MORE HEIGHT FALLS DOWNSTREAM OF THE LOW THAN HEIGHT RISES UPSTREAM/...AS COLD FRONT STRETCHING FROM THE OCCLUDED SURFACE LOW SWEEPS ACROSS THE MISSISSIPPI VALLEY. THE MAIN CONCERN FOR THE PERIOD REMAINS CONVECTION TRENDS FOR TODAY. LINE OF SHOWERS AND THUNDERSTORMS CURRENTLY STRETCHED FROM MIDDLE TENNESSEE THROUGH ALABAMA AT AFD TIME...WELL AHEAD OF THE COLD FRONT...AND SHOULD REACH EXTREME NORTHWEST ZONES WITHIN THE HOUR. INSTABILITY IS MINIMAL WITH NO SBCAPE SHOWING UP IN MESOANALYSIS... AND MUCAPE VALUES AT BEST AROUND 250 J/KG...SO THE DRIVING FORCE BEHIND THE CONVECTION IS SIMPLY THE SYNOPTIC SCALE LIFT...OF WHICH THERE IS PLENTY. MOST HIRES GUIDANCE REALLY BREAKS THE SYSTEM DOWN AS IT MOVES INTO GEORGIA...THOUGH THE HRRR DOES KEEP SOME SEMBLANCE OF ORGANIZED CONVECTION. LIGHTNING ACTIVITY HAS DECREASED IN THE LINE OVER THE LAST HOUR OR SO. SREF GUIDANCE IS HARD-PRESSED TO BRING ANY CAPE INTO THE AREA UNTIL THIS AFTERNOON. SO WITH THAT SAID...HAVE SORT OF TAKEN A COMPROMISE BETWEEN EXTRAPOLATING WHAT IS ALREADY OUT THERE AND THE SUITE OF HIRES GUIDANCE. BRING CATEGORICAL POPS INTO NORTHWEST GEORGIA OVER THE NEXT FEW HOURS WITH DEFINITE THUNDER AT THE ONSET...THEN DECREASE THUNDER WORDING AS PRECIPITATION SPREADS TOWARD THE METRO AREA BY 12Z. BROUGHT ADDITIONAL THUNDER BACK IN THIS AFTERNOON ACROSS SOUTHERN ZONES AS INSTABILITY INCREASES WITH AFTERNOON HEATING. NO REAL CONCERN WITH SEVERE WEATHER AS BEST SHEAR WILL REMAIN TO OUR NORTH AND NORTHEAST TODAY...BUT CANNOT TOTALLY RULE OUT THE POSSIBILITY OF AN ISOLATED STRONG TO POSSIBLY SEVERE THUNDERSTORM ACROSS CENTRAL GEORGIA THIS AFTERNOON. GUSTY WINDS WILL BE THE MAIN THREAT. OTHERWISE...FOR THE MOST PART LOOKS LIKE A QUICK SHOT OF RAIN...WITH HIGHEST AMOUNTS NORTHWEST POSSIBLY UP TO A HALF INCH. COLD FRONT SWEEPS THROUGH BEHIND THE AREA OF RAIN...WITH DRIER AIR MOVING IN BEHIND IT. WHILE MASS FIELDS REMAIN VERY SIMILAR...MORE DIFFERENCES BEGIN TO CREEP IN BETWEEN THE NAM AND GFS...WITH MET GUIDANCE REMAINING A LITTLE MORE MOIST AND THUS A LITTLE WARMER OVERNIGHT...WITH WARMER TEMPS ON FRIDAY AS WELL. AGAIN...LEANED GENERALLY TOWARD A BLEND BUT LEANED SLIGHTLY ON THE COOLER SIDE. LOW TEMPS TONIGHT IN SOME AREAS MAY FLIRT WITH THE UPPER 30S. THIS WILL BE HEAVILY DEPENDENT ON DEWPOINTS...AND LOOKING UPSTREAM BEHIND THE FRONT THE DEWPOINTS ARE QUITE DRY. OBVIOUSLY SOME MODIFICATION OF THE AIRMASS CAN BE EXPECTED...BUT EITHER WAY IT LOOKS LIKE TONIGHT WILL PROBABLY HAVE THE COLDEST TEMPS OF THE SEASON THUS FAR. OTHER ITEM OF NOTE WILL BE WINDS IN THE MOUNTAINS ON FRIDAY. AS THE LOW DIGS SOUTHEAST TOWARD THE GREAT LAKES TODAY AND FRIDAY...THERE MIGHT BE ENOUGH OF A GRADIENT IN THE MOUNTAINS FRIDAY AFTERNOON BEFORE THE SURFACE HIGH BEGINS TO BUILD IN FOR POSSIBLE WIND ADVISORY CRITERIA. TOO EARLY AT THIS POINT BUT WILL REEVALUATE WITH LATER FORECASTS. TDP LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... THE LONG TERM LOOKS TO HAVE MUCH LESS ACTIVITY IN STORE THAN THE SHORT TERM...AS A DRY FORECAST DOMINATED BY HIGH PRESSURE IS ON TAP. GUIDANCE IS IN GENERAL AGREEMENT WITH A WEAK SHORTWAVE PUSHING THROUGH THE FORECAST AREA FRIDAY NIGHT AS IT ROTATES AROUND THE BROAD UPPER CLOSED LOW CENTERED OVER THE GREAT LAKES. HOWEVER...THIS ENERGY SHOULD BE TOO REMOVED FROM THE MOISTURE FIELD NORTH OF THE AREA TO TRANSLATE TO ANY PRECIP CHANCES AND THE UPPER TROUGH AXIS SHOULD BE EAST OF THE AREA BY LATER SATURDAY...THEREFORE WILL KEEP DRY CONDITIONS AS THE UPPER RIDGE BUILDS IN FOR NEXT WEEK. MEX GUIDANCE TEMPS CONTINUE TO LOOK TOO COOL SO HAVE RAISED A BIT BASED ON PREVIOUS TRENDS...KEEPING MUCH OF THE AREA NEAR SEASONABLE VALUES TO SLIGHTLY ABOVE NORMAL FROM SUNDAY ONWARD. BAKER && .AVIATION... 18Z UPDATE... MIXTURE OF MVFR/VFR CONDITIONS CURRENTLY WITH GRADUAL IMPROVEMENTS TO WIDESPREAD VFR BY 20Z-00Z. CLOUD SEE LOCAL TO SCATTERED MVFR VISIBILITIES DUE TO FOG ACROSS CENTRAL GEORGIA BETWEEN 08Z AND 14Z...BUT FOR NOW I DO NOT EXPECT THIS TO EFFECT ANY OF THE TAF SITES AS DRIER AIR AND SUFFICIENT LOW-LEVEL WINDS SHOULD KEEP THE MOST AREAS FOG-FREE. WINDS ALREADY SW-W OR TURNING THAT DIRECTION AND THE TREND TOWARD W WINDS WILL CONTINUE AND SPREAD EAST THROUGH THE PERIOD. WIND SPEEDS ARE EXPECTED IN THE 6-10KT RANGE THROUGH 00Z...DIMINISHING TO 3-6KT THROUGH 14Z BEFORE INCREASING INTO THE 8-12KT RANGE 14Z-18Z. WIND GUSTS UP TO 14-16KT POSSIBLE THIS AFTERNOON...GENERALLY BETWEEN 18Z-22Z...WITH GUSTS 14-18KT RETURNING AFTER 14Z FRIDAY. ISOLATED TO SCATTERED SHOWERS THIS AFTERNOON AND EVENING SHOULD REMAIN MAINLY SOUTH OF THE TAF SITES. //ATL CONFIDENCE...18Z UPDATE... MEDIUM FOR TIMING OF CLOUDS LIFTING AND DIMINISHING THROUGH 00Z... OTHERWISE HIGH. && .PRELIMINARY POINT TEMPS/POPS... ATHENS 72 46 73 47 / 80 10 5 5 ATLANTA 72 51 73 47 / 40 10 0 5 BLAIRSVILLE 66 42 66 40 / 10 5 0 5 CARTERSVILLE 72 40 72 44 / 10 5 0 5 COLUMBUS 79 51 76 49 / 80 10 5 5 GAINESVILLE 69 48 71 46 / 50 5 0 5 MACON 79 47 77 46 / 60 20 5 5 ROME 73 39 71 43 / 10 5 0 5 PEACHTREE CITY 74 41 74 43 / 50 10 0 5 VIDALIA 81 61 79 53 / 50 30 10 5 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
743 AM EDT THU OCT 18 2012 .PREV DISCUSSION... /ISSUED 330 AM EDT THU OCT 18 2012/ SHORT TERM /TODAY THROUGH FRIDAY/... NAM/GFS/ECMWF IN DECENT AGREEMENT THROUGH THE SHORT TERM...SO WENT WITH A GENERAL BLEND FOR MOST ELEMENTS. LARGE MID LEVEL LOW SPINNING OVER THE US/CANADA BORDER CONTINUES TO DEEPEN AND PROPAGATE SOUTHEAST /500MB 00Z UA ANALYSIS HAD MORE HEIGHT FALLS DOWNSTREAM OF THE LOW THAN HEIGHT RISES UPSTREAM/...AS COLD FRONT STRETCHING FROM THE OCCLUDED SURFACE LOW SWEEPS ACROSS THE MISSISSIPPI VALLEY. THE MAIN CONCERN FOR THE PERIOD REMAINS CONVECTION TRENDS FOR TODAY. LINE OF SHOWERS AND THUNDERSTORMS CURRENTLY STRETCHED FROM MIDDLE TENNESSEE THROUGH ALABAMA AT AFD TIME...WELL AHEAD OF THE COLD FRONT...AND SHOULD REACH EXTREME NORTHWEST ZONES WITHIN THE HOUR. INSTABILITY IS MINIMAL WITH NO SBCAPE SHOWING UP IN MESOANALYSIS... AND MUCAPE VALUES AT BEST AROUND 250 J/KG...SO THE DRIVING FORCE BEHIND THE CONVECTION IS SIMPLY THE SYNOPTIC SCALE LIFT...OF WHICH THERE IS PLENTY. MOST HIRES GUIDANCE REALLY BREAKS THE SYSTEM DOWN AS IT MOVES INTO GEORGIA...THOUGH THE HRRR DOES KEEP SOME SEMBLANCE OF ORGANIZED CONVECTION. LIGHTNING ACTIVITY HAS DECREASED IN THE LINE OVER THE LAST HOUR OR SO. SREF GUIDANCE IS HARD-PRESSED TO BRING ANY CAPE INTO THE AREA UNTIL THIS AFTERNOON. SO WITH THAT SAID...HAVE SORT OF TAKEN A COMPROMISE BETWEEN EXTRAPOLATING WHAT IS ALREADY OUT THERE AND THE SUITE OF HIRES GUIDANCE. BRING CATEGORICAL POPS INTO NORTHWEST GEORGIA OVER THE NEXT FEW HOURS WITH DEFINITE THUNDER AT THE ONSET...THEN DECREASE THUNDER WORDING AS PRECIPITATION SPREADS TOWARD THE METRO AREA BY 12Z. BROUGHT ADDITIONAL THUNDER BACK IN THIS AFTERNOON ACROSS SOUTHERN ZONES AS INSTABILITY INCREASES WITH AFTERNOON HEATING. NO REAL CONCERN WITH SEVERE WEATHER AS BEST SHEAR WILL REMAIN TO OUR NORTH AND NORTHEAST TODAY...BUT CANNOT TOTALLY RULE OUT THE POSSIBILITY OF AN ISOLATED STRONG TO POSSIBLY SEVERE THUNDERSTORM ACROSS CENTRAL GEORGIA THIS AFTERNOON. GUSTY WINDS WILL BE THE MAIN THREAT. OTHERWISE...FOR THE MOST PART LOOKS LIKE A QUICK SHOT OF RAIN...WITH HIGHEST AMOUNTS NORTHWEST POSSIBLY UP TO A HALF INCH. COLD FRONT SWEEPS THROUGH BEHIND THE AREA OF RAIN...WITH DRIER AIR MOVING IN BEHIND IT. WHILE MASS FIELDS REMAIN VERY SIMILAR...MORE DIFFERENCES BEGIN TO CREEP IN BETWEEN THE NAM AND GFS...WITH MET GUIDANCE REMAINING A LITTLE MORE MOIST AND THUS A LITTLE WARMER OVERNIGHT...WITH WARMER TEMPS ON FRIDAY AS WELL. AGAIN...LEANED GENERALLY TOWARD A BLEND BUT LEANED SLIGHTLY ON THE COOLER SIDE. LOW TEMPS TONIGHT IN SOME AREAS MAY FLIRT WITH THE UPPER 30S. THIS WILL BE HEAVILY DEPENDENT ON DEWPOINTS...AND LOOKING UPSTREAM BEHIND THE FRONT THE DEWPOINTS ARE QUITE DRY. OBVIOUSLY SOME MODIFICATION OF THE AIRMASS CAN BE EXPECTED...BUT EITHER WAY IT LOOKS LIKE TONIGHT WILL PROBABLY HAVE THE COLDEST TEMPS OF THE SEASON THUS FAR. OTHER ITEM OF NOTE WILL BE WINDS IN THE MOUNTAINS ON FRIDAY. AS THE LOW DIGS SOUTHEAST TOWARD THE GREAT LAKES TODAY AND FRIDAY...THERE MIGHT BE ENOUGH OF A GRADIENT IN THE MOUNTAINS FRIDAY AFTERNOON BEFORE THE SURFACE HIGH BEGINS TO BUILD IN FOR POSSIBLE WIND ADVISORY CRITERIA. TOO EARLY AT THIS POINT BUT WILL REEVALUATE WITH LATER FORECASTS. TDP LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... THE LONG TERM LOOKS TO HAVE MUCH LESS ACTIVITY IN STORE THAN THE SHORT TERM...AS A DRY FORECAST DOMINATED BY HIGH PRESSURE IS ON TAP. GUIDANCE IS IN GENERAL AGREEMENT WITH A WEAK SHORTWAVE PUSHING THROUGH THE FORECAST AREA FRIDAY NIGHT AS IT ROTATES AROUND THE BROAD UPPER CLOSED LOW CENTERED OVER THE GREAT LAKES. HOWEVER...THIS ENERGY SHOULD BE TOO REMOVED FROM THE MOISTURE FIELD NORTH OF THE AREA TO TRANSLATE TO ANY PRECIP CHANCES AND THE UPPER TROUGH AXIS SHOULD BE EAST OF THE AREA BY LATER SATURDAY...THEREFORE WILL KEEP DRY CONDITIONS AS THE UPPER RIDGE BUILDS IN FOR NEXT WEEK. MEX GUIDANCE TEMPS CONTINUE TO LOOK TOO COOL SO HAVE RAISED A BIT BASED ON PREVIOUS TRENDS...KEEPING MUCH OF THE AREA NEAR SEASONABLE VALUES TO SLIGHTLY ABOVE NORMAL FROM SUNDAY ONWARD. BAKER && .AVIATION... 12Z UPDATE... SHRA MOVING OUT OF THE ATL METRO AREA...BEGINNING TO AFFECT OTHER TAFS AT 12Z. MVFR CIGS ALSO MOVING IN FROM BOTH THE NE AND THE NW...HAVE INCLUDED IT IN THE NORTHERN TAFS EXCEPT ATL FOR THIS MORNING. STILL EXPECT THE WIND SHIFT AROUND 14Z WITH CLEARING THEREAFTER NORTH. FOR MCN AND CSG...MAY STILL SEE CONVECTION THROUGH THE AFTERNOON HOURS OFF AND ON. FOR NOW HAVE ONLY KEPT VCSH BUT WILL MONITOR IN CASE TEMPO TSRA IS NEEDED. //ATL CONFIDENCE...12Z UPDATE... HIGH ON WINDS...PRECIP ENDING...AND CIGS AFTER 18Z. MEDIUM ON CIGS THIS MORNING. TDP && .PRELIMINARY POINT TEMPS/POPS... ATHENS 72 46 73 47 / 80 10 5 5 ATLANTA 72 51 73 47 / 40 10 0 5 BLAIRSVILLE 66 42 66 40 / 10 5 0 5 CARTERSVILLE 72 40 72 44 / 10 5 0 5 COLUMBUS 79 51 76 49 / 80 10 5 5 GAINESVILLE 69 48 71 46 / 50 5 0 5 MACON 79 47 77 46 / 60 20 5 5 ROME 73 39 71 43 / 10 5 0 5 PEACHTREE CITY 74 41 74 43 / 50 10 0 5 VIDALIA 81 61 79 53 / 50 30 10 5 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
330 AM EDT THU OCT 18 2012 .SHORT TERM /TODAY THROUGH FRIDAY/... NAM/GFS/ECMWF IN DECENT AGREEMENT THROUGH THE SHORT TERM...SO WENT WITH A GENERAL BLEND FOR MOST ELEMENTS. LARGE MID LEVEL LOW SPINNING OVER THE US/CANADA BORDER CONTINUES TO DEEPEN AND PROPAGATE SOUTHEAST /500MB 00Z UA ANALYSIS HAD MORE HEIGHT FALLS DOWNSTREAM OF THE LOW THAN HEIGHT RISES UPSTREAM/...AS COLD FRONT STRETCHING FROM THE OCCLUDED SURFACE LOW SWEEPS ACROSS THE MISSISSIPPI VALLEY. THE MAIN CONCERN FOR THE PERIOD REMAINS CONVECTION TRENDS FOR TODAY. LINE OF SHOWERS AND THUNDERSTORMS CURRENTLY STRETCHED FROM MIDDLE TENNESSEE THROUGH ALABAMA AT AFD TIME...WELL AHEAD OF THE COLD FRONT...AND SHOULD REACH EXTREME NORTHWEST ZONES WITHIN THE HOUR. INSTABILITY IS MINIMAL WITH NO SBCAPE SHOWING UP IN MESOANALYSIS... AND MUCAPE VALUES AT BEST AROUND 250 J/KG...SO THE DRIVING FORCE BEHIND THE CONVECTION IS SIMPLY THE SYNOPTIC SCALE LIFT...OF WHICH THERE IS PLENTY. MOST HIRES GUIDANCE REALLY BREAKS THE SYSTEM DOWN AS IT MOVES INTO GEORGIA...THOUGH THE HRRR DOES KEEP SOME SEMBLANCE OF ORGANIZED CONVECTION. LIGHTNING ACTIVITY HAS DECREASED IN THE LINE OVER THE LAST HOUR OR SO. SREF GUIDANCE IS HARD-PRESSED TO BRING ANY CAPE INTO THE AREA UNTIL THIS AFTERNOON. SO WITH THAT SAID...HAVE SORT OF TAKEN A COMPROMISE BETWEEN EXTRAPOLATING WHAT IS ALREADY OUT THERE AND THE SUITE OF HIRES GUIDANCE. BRING CATEGORICAL POPS INTO NORTHWEST GEORGIA OVER THE NEXT FEW HOURS WITH DEFINITE THUNDER AT THE ONSET...THEN DECREASE THUNDER WORDING AS PRECIPITATION SPREADS TOWARD THE METRO AREA BY 12Z. BROUGHT ADDITIONAL THUNDER BACK IN THIS AFTERNOON ACROSS SOUTHERN ZONES AS INSTABILITY INCREASES WITH AFTERNOON HEATING. NO REAL CONCERN WITH SEVERE WEATHER AS BEST SHEAR WILL REMAIN TO OUR NORTH AND NORTHEAST TODAY...BUT CANNOT TOTALLY RULE OUT THE POSSIBILITY OF AN ISOLATED STRONG TO POSSIBLY SEVERE THUNDERSTORM ACROSS CENTRAL GEORGIA THIS AFTERNOON. GUSTY WINDS WILL BE THE MAIN THREAT. OTHERWISE...FOR THE MOST PART LOOKS LIKE A QUICK SHOT OF RAIN...WITH HIGHEST AMOUNTS NORTHWEST POSSIBLY UP TO A HALF INCH. COLD FRONT SWEEPS THROUGH BEHIND THE AREA OF RAIN...WITH DRIER AIR MOVING IN BEHIND IT. WHILE MASS FIELDS REMAIN VERY SIMILAR...MORE DIFFERENCES BEGIN TO CREEP IN BETWEEN THE NAM AND GFS...WITH MET GUIDANCE REMAINING A LITTLE MORE MOIST AND THUS A LITTLE WARMER OVERNIGHT...WITH WARMER TEMPS ON FRIDAY AS WELL. AGAIN...LEANED GENERALLY TOWARD A BLEND BUT LEANED SLIGHTLY ON THE COOLER SIDE. LOW TEMPS TONIGHT IN SOME AREAS MAY FLIRT WITH THE UPPER 30S. THIS WILL BE HEAVILY DEPENDENT ON DEWPOINTS...AND LOOKING UPSTREAM BEHIND THE FRONT THE DEWPOINTS ARE QUITE DRY. OBVIOUSLY SOME MODIFICATION OF THE AIRMASS CAN BE EXPECTED...BUT EITHER WAY IT LOOKS LIKE TONIGHT WILL PROBABLY HAVE THE COLDEST TEMPS OF THE SEASON THUS FAR. OTHER ITEM OF NOTE WILL BE WINDS IN THE MOUNTAINS ON FRIDAY. AS THE LOW DIGS SOUTHEAST TOWARD THE GREAT LAKES TODAY AND FRIDAY...THERE MIGHT BE ENOUGH OF A GRADIENT IN THE MOUNTAINS FRIDAY AFTERNOON BEFORE THE SURFACE HIGH BEGINS TO BUILD IN FOR POSSIBLE WIND ADVISORY CRITERIA. TOO EARLY AT THIS POINT BUT WILL REEVALUATE WITH LATER FORECASTS. TDP && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... THE LONG TERM LOOKS TO HAVE MUCH LESS ACTIVITY IN STORE THAN THE SHORT TERM...AS A DRY FORECAST DOMINATED BY HIGH PRESSURE IS ON TAP. GUIDANCE IS IN GENERAL AGREEMENT WITH A WEAK SHORTWAVE PUSHING THROUGH THE FORECAST AREA FRIDAY NIGHT AS IT ROTATES AROUND THE BROAD UPPER CLOSED LOW CENTERED OVER THE GREAT LAKES. HOWEVER...THIS ENERGY SHOULD BE TOO REMOVED FROM THE MOISTURE FIELD NORTH OF THE AREA TO TRANSLATE TO ANY PRECIP CHANCES AND THE UPPER TROUGH AXIS SHOULD BE EAST OF THE AREA BY LATER SATURDAY...THEREFORE WILL KEEP DRY CONDITIONS AS THE UPPER RIDGE BUILDS IN FOR NEXT WEEK. MEX GUIDANCE TEMPS CONTINUE TO LOOK TOO COOL SO HAVE RAISED A BIT BASED ON PREVIOUS TRENDS...KEEPING MUCH OF THE AREA NEAR SEASONABLE VALUES TO SLIGHTLY ABOVE NORMAL FROM SUNDAY ONWARD. BAKER && .AVIATION... 06Z UPDATE... SHRA AND TSRA AHEAD OF COLD FRONT WILL PUSH INTO NW GA 07-08Z... BUT IS WEAKENING. REMOVED TSRA FROM NORTHERN TAFS...KEEPING -SHRA INSTEAD. EXPECT AT LEAST A BRIEF PERIOD OF MVFR WITH THE SHRA BUT LIFTING CIGS BEHIND THE RAIN AS THE LINE MOVES EAST. SE WINDS AROUND 5KT OR SO TO START THE PERIOD...SHIFTING TO WEST AND INCREASING AROUND 14Z ATL METRO AREA AND CSG...LATER FOR CSG AND MCN. MAY SEE SOME LOW-END GUSTS THROUGH THE AFTERNOON. CLEARING LATE TODAY AND TONIGHT. //ATL CONFIDENCE...06Z UPDATE... HIGH ON -SHRA. LOW ON POTENTIAL FOR -TSRA. MEDIUM ON TIMING. HIGH ON MVFR CIGS...MEDIUM ON TIMING. HIGH ON WINDS. TDP && .PRELIMINARY POINT TEMPS/POPS... ATHENS 72 46 73 47 / 60 10 5 5 ATLANTA 72 51 73 47 / 50 10 0 5 BLAIRSVILLE 66 42 66 40 / 20 5 0 5 CARTERSVILLE 72 40 72 44 / 20 5 0 5 COLUMBUS 79 51 76 49 / 60 10 5 5 GAINESVILLE 69 48 71 46 / 50 5 0 5 MACON 79 47 77 46 / 50 20 5 5 ROME 73 39 71 43 / 20 5 0 5 PEACHTREE CITY 74 41 74 43 / 50 10 0 5 VIDALIA 81 61 79 53 / 30 30 10 5 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...TDP LONG TERM....BAKER AVIATION...TDP
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
148 AM EDT THU OCT 18 2012 .PREV DISCUSSION... /ISSUED 1022 PM EDT WED OCT 17 2012/ UPDATE... CONTINUE TO MONITOR TRENDS ON IR SATELLITE AND RADAR OF CONVECTION IN THE MID-SOUTH AS IT ENTERS WESTERN TENNESSEE. FORECAST HAS BEEN UPDATED TO ACCOUNT FOR EARLIER TIMING OF THIS SYSTEM...ENTERING NORTH GEORGIA EARLY THURSDAY MORNING. LATEST LOCAL WRF AND NATIONAL HRRR MODEL GUIDANCE CONTINUES TO INDICATE THAT ACTIVITY SHOULD BEGIN TO FALL APART AS IT MOVES THROUGH METRO ATLANTA BETWEEN 08Z AND 10Z THURSDAY MORNING. AVAILABLE INSTABILITY SHOULD ALLOW THE LINE TO PRODUCE SOME THUNDERSTORMS IN NORTH GEORGIA TONIGHT. CANNOT RULE OUT AN ISOLATED EMBEDDED TORNADO AS THIS LINE PUSHES THROUGH...WITH 0-1 KM SHEAR VALUES NEARING 55 KTS...ALTHOUGH THE THREAT OF A STRAIGHT LINE WIND EVENT IS SLIGHTLY MORE LIKELY GIVEN THE LITTLE DIRECTIONAL 0-1 KM SHEAR IN NORTH GEORGIA OVERNIGHT ACCORDING TO THE 22Z HRRR RUN. RAG/37 PREV DISCUSSION... SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/... /ISSUED AT 255 PM EDT WED OCT 17 2012/ UPPER LEVEL FLOW TRANSITIONING FROM A FLAT...NEARLY ZONAL...PATTERN ACROSS THE CONTINENTAL U.S. TO A RELATIVELY STATIC...HIGH AMPLITUDE PATTERN AS A STRONG SHORT WAVE DIVING OUT OF CANADA DIGS A DEEP UPPER LOW INTO THE UPPER MISSISSIPPI VALLEY TONIGHT. STRONG...DEEP SURFACE LOW ASSOCIATED WITH THIS SYSTEM REMAINS WELL NORTH OF GEORGIA BUT DRIVES A COLD FRONT INTO NORTHWEST GEORGIA EARLY THURSDAY. MOISTURE IS VERY LIMITED CURRENTLY...BUT DEEPENING NATURE OF THE SYSTEM PULLS SUFFICIENT MOISTURE NORTH AHEAD OF THE FRONT FOR HIGH CHANCE TO LIKELY POPS ALONG AND JUST AHEAD OF THE FRONT SWEEPING NORTHWEST TO SOUTHEAST ACROSS THE FORECAST AREA FROM LATE TONIGHT THROUGH THURSDAY EVENING. RIGHT NOW ONLY THE NAM IS GENERATING ENOUGH INSTABILITY FOR THUNDER...SO I WILL KEEP THUNDERSTORMS LIMITED TO SLIGHT CHANCE. PRECIPITATION PUSHES SOUTHEAST OUT OF THE FORECAST AREA THURSDAY NIGHT AS DRIER AIR SWEEPS IN BEHIND THE FRONT. RIGHT NOW MODEL TRENDS ARE FOR CLEARING SKIES THURSDAY NIGHT THROUGH FRIDAY...HOWEVER THE DEEP UPPER LOW REMAINS ESSENTIALLY STATIONARY OVER THE SOUTHERN GREAT LAKES/WESTERN OHIO VALLEY SO WE WILL NEED TO KEEP AN EYE ON TRENDS FOR POTENTIALLY MORE CLOUD COVER ACROSS AT LEAST NORTH GEORGIA THROUGH THE PERIOD. 20 LONG TERM /FRIDAY THROUGH WEDNESDAY/... NO CHANGES FROM PREVIOUS LONG TERM. PREVIOUS LONG TERM DISCUSSION FOLLOWS. /ISSUED AT 336 AM EDT WED OCT 17 2012/ IN THE WAKE OF THE FRONTAL SYSTEM EXITING THE FORECAST AREA THURSDAY NIGHT...THE UPPER LEVEL TROUGH AXIS OF A BROAD UPPER CLOSED LOW CENTERED ACROSS THE GREAT LAKES SHOULD REMAIN WEST OF THE AREA UNTIL THE SATURDAY NIGHT/EARLY SUNDAY TIME PERIOD. GUIDANCE IS IN OVERALL AGREEMENT WITH THE MOISTURE FIELD STAYING NORTH OF THE AREA WITH NO SIGNIFICANT SHORTWAVE INFLUENCE. THE BEST CHANCE FOR ANY PRECIP WOULD BE FRIDAY NIGHT WITH A WEAK SHORTWAVE IMPULSE ROTATING THROUGH GEORGIA. AT THIS POINT...IT LOOKS LIKE IF ANY LOCATION HAD A CHANCE FOR PRECIP IT WOULD BE THE NORTHERN PORTION OF THE AREA CLOSER TO THE HIGHER PROGGED LAYER RH VALUES. HOWEVER...WITH THE ENERGY BEING A BIT TOO FAR SOUTH FROM THE MOISTURE AND A SFC HIGH FILTERING IN FROM THE WEST...IT SHOULD RESULT IN ONLY AN ENHANCEMENT IN CLOUD COVERAGE SO WILL KEEP A DRY FORECAST. THE DRY AND PLEASANT WEATHER SHOULD PERSIST THROUGH THE REMAINDER OF THE LONG TERM AS GUIDANCE IS IN GOOD CONSENSUS WITH A 1020-1022 MB SFC HIGH SETTING UP ACROSS THE CAROLINAS BY THE END OF THE WEEKEND AND PERSISTING THROUGH TUESDAY. THIS SHOULD BRING WEAK SOUTHEASTERLY TO SOUTHERLY FLOW ACROSS THE AREA. FOR TEMPS...LATEST MEX GUIDANCE SEEMED SLIGHTLY COOL ON DAYTIME MAX VALUES SO STAYED A BIT HIGHER. OTHERWISE...SHOULD SEE OVERNIGHT LOWS MAINLY IN THE 40S HEADING INTO THE WEEKEND...THEN WARMING UP GRADUALLY INTO THE UPPER 40S AND LOW 50S BY EARLY NEXT WEEK. HIGHS WILL START OUT COOL IN THE UPPER 60S TO 70S AND GRADUALLY WARM INTO THE LOW TO UPPER 70S BY SUNDAY. BAKER && .AVIATION... 06Z UPDATE... SHRA AND TSRA AHEAD OF COLD FRONT WILL PUSH INTO NW GA 07-08Z... BUT IS WEAKENING. REMOVED TSRA FROM NORTHERN TAFS...KEEPING -SHRA INSTEAD. EXPECT AT LEAST A BRIEF PERIOD OF MVFR WITH THE SHRA BUT LIFTING CIGS BEHIND THE RAIN AS THE LINE MOVES EAST. SE WINDS AROUND 5KT OR SO TO START THE PERIOD...SHIFTING TO WEST AND INCREASING AROUND 14Z ATL METRO AREA AND CSG...LATER FOR CSG AND MCN. MAY SEE SOME LOW-END GUSTS THROUGH THE AFTERNOON. CLEARING LATE TODAY AND TONIGHT. //ATL CONFIDENCE...06Z UPDATE... HIGH ON -SHRA. LOW ON POTENTIAL FOR -TSRA. MEDIUM ON TIMING. HIGH ON MVFR CIGS...MEDIUM ON TIMING. HIGH ON WINDS. TDP && .PRELIMINARY POINT TEMPS/POPS... ATHENS 73 45 73 47 / 50 10 5 0 ATLANTA 73 49 72 48 / 60 5 0 0 BLAIRSVILLE 67 40 66 41 / 60 5 0 0 CARTERSVILLE 71 40 71 43 / 60 5 0 0 COLUMBUS 76 50 77 50 / 40 10 5 5 GAINESVILLE 72 47 70 47 / 50 5 0 0 MACON 77 46 76 46 / 50 10 5 5 ROME 71 40 73 43 / 50 5 0 0 PEACHTREE CITY 73 42 73 42 / 50 5 5 0 VIDALIA 81 60 80 54 / 40 20 10 0 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
900 PM CDT FRI OCT 19 2012 .DISCUSSION... ISSUED 855 PM CDT FRI OCT 19 2012 UPDATED THE FORECAST THIS EVENING TO INCREASE CHANCE OF SHOWERS FROM LINCOLN NORTHEAST AND ALSO ADDED PATCHY FOG LATE TONIGHT NORTH OF LINCOLN WITH SOME DECREASING LOW CLOUDS LATE. COOLED LOWS CLOSER TO 40F OVER THE IL RIVER VALLEY WITH 40 TO 45F MOST REST OF CENTRAL AND SE IL. WEST WINDS OF 8 TO 16 MPH THIS EVENING DIMINISHING TO 5 TO 10 MPH OVERNIGHT. LOW CLOUDS BLANKET CENTRAL AND SE IL THIS EVENING. STRONG 538 DM 500 MB LOW OVER SOUTHERN LAKE MI HAS A FAIRLY STRONG SHORT WAVE OVER NW IL PIVOTING SE INTO CENTRAL IL DURING MID EVENING WITH ONE MORE BATCH OF SHOWERS AFFECTING AREAS FROM LINCOLN NE UNTIL MIDNIGHT. POCKETS OF HEAVIER RAIN NE OF I-74 AND HAD A REPORT OF PEA SIZE GRAPEL (SOFT HAIL) AT HOOPESTON AT 555 PM. 1001 MB SURFACE LOW WAS OVER SE LAKE MICHIGAN AND GRADUALLY WEAKENING TODAY SINCE LOW PRESSURE SYSTEM IS NEARLY VERTICALLY STACKED. COOL TEMPS CURRENTLY IN THE UPPER 40S AND LOWER 50S WITH WSW WINDS 8 TO 16 MPH AND A FEW GUSTS NEAR 20 MPH. THE HRRR MODEL HANDLED QPF FIELDS THE BEST AND USED IT FOR THE FORECAST UPDATE THIS EVENING WITH LIKELY CHANCES OF SHOWERS OVER AREAS NE OF LINCOLN UNTIL MIDNIGHT. COULD BE A FEW LINGERING LIGHT RAIN SHOWERS OR DRIZZLE EARLY OVERNIGHT FROM LINCOLN EAST. A LARGE BREAK IN THE LOW CLOUDS OVER THE UPPER MS VALLEY OF NE IA...EASTERN MN AND WESTERN WI TO TRACK SSE INTO THE IL RIVER VALLEY LATER TONIGHT SO DECREASED CLOUDS THERE TO BECOME PARTLY CLOUDY LATE AND ADDED PATCHY FOG LATE TONIGHT UNTIL MID MORNING SAT NORTH OF LINCOLN. MODELS TAKE LOW PRESSURE JUST EAST OF SE PARTS OF LOWER MI BY SUNRISE AND INTO SE ONTARIO BY 18Z/SAT. SO SHOWERS TO DIMINISH BY EARLY OVERNIGHT WITH LOW CLOUDS DECREASE FROM NW TO SE LATER TONIGHT AND SAT MORNING. LOWS MOSTLY 40 TO 45F...CLOSER TO 40F OVER THE IL RIVER VALLEY WHERE SOME DECREASING CLOUDS EXPECTED LATER. 07 && .AVIATION... ISSUED 655 PM CDT FRI OCT 19 2012 VFR BROKEN TO OVERCAST CEILINGS OF 4-6K FT WILL LOWER TO MVFR DURING THIS EVENING. MVFR VSBYS POSSIBLE AS WELL AS SCATTERED LIGHT RAIN SHOWERS NW OF THE IL RIVER INTO EAST CENTRAL IA SPREAD SE ACROSS CENTRAL IL DURING EARLY AND MID EVENING. THESE LIGHT SHOWERS CAUSED BY ANOTHER SHORT WAVE OVER EASTERN IA/NW IL THAT IS PIVOTING SE INTO CENTRAL IL THIS EVENING AROUND STRONG BUT WEAKENING 538 DM 500 MB LOW PRESSURE NEAR CHICAGO. THIS UPPER LEVEL LOW TO MOVE TOWARD DETROIT LATE TONIGHT AND INTO SE ONTARIO BY SUNSET SAT. FORECAST SOUNDINGS SHOW LOW CLOUDS LOWERING DURING TONIGHT AND THEN SCATTERING OUT FROM NW TO SE DURING SAT MORNING...THOUGH NOT AT CMI UNTIL EARLY SAT AFTERNOON. MVFR CEILINGS COULD LIFT TO VFR DURING SAT MORNING BEFORE SCATTERING OUT. A FEW MODELS SHOW FOG DEVELOPMENT AT PIA AND BMI LATER TONIGHT INTO MID MORNING SAT ESPECIALLY IF LOW CLOUDS SCATTERED OUT SOONER. 1001 MB SURFACE LOW PRESSURE OVER SOUTHERN LAKE MI WEAKENING AS WELL AND TO LIFT NE INTO LAKE HURON BY SUNRISE AND INTO SE CANADA SAT. LIGHER WEST WINDS TO DIMINISH TO 5-10 KTS THIS EVENING AND BE WEST 7-10 KTS SAT AND BECOME LIGHT LATE SAT WITH FAIR SKIES. 07 && .PREV DISCUSSION... ISSUED 254 PM CDT FRI OCT 19 2012 THE CHILLY CUT-OFF LOW WILL FINALLY MAKE AN EXIT TO THE EAST BY SATURDAY MORNING...BRINGING AN END TO THIS ROUND OF COLD RAIN/DRIZZLE TOWARD MIDNIGHT TONIGHT. CLOUDS WILL BE TOUGH TO CLEAR OUT...BUT SUNSHINE SHOULD DEVELOP ON SATURDAY...HELPING TO JUMP START OUR WARMING TREND. AN EXTENDED PERIOD OF ABOVE NORMAL TEMPS WILL HIGHLIGHT THE EXTENDED FORECAST FROM SUNDAY THROUGH THURSDAY. A LATE WEEK COLD FRONT WILL BRING NUMBERS BACK TOWARD OR BELOW NORMAL FOR FRIDAY AND INTO NEXT WEEKEND. RAIN CHANCES WILL BE FOCUSED FROM MONDAY THROUGH TUES WITH STRONG WARM ADVECTION AND A NEARBY LOW PRESSURE/FRONTAL SYSTEM...AND AGAIN WITH THE THURS/THUR NIGHT COLD FRONT. SHORT TERM...TONIGHT THROUGH TUESDAY. THE CHILLY AIRMASS WITH 850MB TEMPS AROUND -1C OVERHEAD IS HELPING PRODUCE FAVORABLE CONDITIONS FOR SHOWERY PRECIP. THE HEAVIER SHOWERS ARE BEING DRIVEN BY 500MB SHORTWAVES...THE NEXT OF WHICH IS APPROACHING OUR NW COUNTIES FROM IOWA. THAT WAVE WILL KEEP SHOWER CHANCES THROUGH THE EVENING ACROSS ALL OF C/SE IL. AS MIXING DIMINISHES AFTER SUNSET...STRATUS AND DRIZZLE MAY BECOME MORE PROMINENT. THE BULK OF THE PRECIP SHOULD BE DONE BY MIDNIGHT...BUT CANT RULE OUT SOME LINGERING DRIZZLE AFTER MIDNIGHT ACROSS THE NORTHEAST. A BLANKET OF LOW CLOUDS WILL REMAIN THROUGH SATURDAY MORNING. CLEARING WILL BEGIN SATURDAY MORNING WITH THE HEATING OF THE DAY AND MIXING OF DRY AIR FROM JUST ABOVE THE CLOUD LAYER. INCREASING SUNSHINE BY AFTERNOON WILL HELP PUSH TEMPS ABOUT 10 DEG F ABOVE TODAY/S READINGS...WITH HIGHS IN THE LOW 60S. MORE SIGNIFICANT WARMING IS ON TAP FOR SUNDAY...WITH PLENTY OF SUNSHINE. HIGHS SHOULD TOP OUT ANOTHER 10-13F ABOVE SATURDAY...WITH READINGS IN THE LOW TO MID 70S. HOWEVER...THE STRONG MID LEVEL WARM ADVECTION WILL ALSO BE ACCOMPANIED BY STRONG MOISTURE FLUX AS WELL. SURFACE DEWPOINTS WILL LIKEWISE CLIMB INTO THE LOWER 60S...AIDING IN POSSIBLE SHOWERS AND THUNDERSTORMS SUNDAY NIGHT. SHOWER/STORM DEVELOPMENT WILL BE ENHANCED BY A SURFACE LOW MOVING OUT OF THE PLAINS UP THROUGH IOWA BY SUNDAY NIGHT AND MONDAY MORNING. INSTABILITY PARAMS SUPPORT THUNDERSTORM DEVELOPMENT... ESPECIALLY DUE TO THE RELATIVELY HIGH SURFACE DEWPOINTS ACCOMPANIED WITH FAVORABLE WIND SHEAR. THE PRECIP CHANCES WILL BE SUSTAINED INTO TUESDAY AS THE REMNANTS OF A TROPICAL SYSTEM /CURRENTLY OFF OF THE BAJA OF CALIFORNIA/ TRAIL INTO OUR AREA QUICKLY ON THE HEELS OF THE INITIAL LOW PRESSURE SYSTEM. LONG TERM...WEDNESDAY THROUGH FRIDAY. THE MAIN EXTENDED FORECAST ISSUE WILL BE TIMING OF THE COLD FRONT FOR EITHER THURSDAY /ECMWF & CANADIAN GEM/ OR THURSDAY NIGHT /GFS/. AHEAD OF THE FRONT...THERE IS GOOD AGREEMENT THAT WED WILL BE A DRY AND WARM DAY...WITH HIGHS POSSIBLY THE WARMEST OF THE NEXT WEEK. SOME UPPER 70S IN OUR SW AREA WITH AT LEAST MID 70S ALL ACROSS OUR AREA. SOME QUESTION MARKS REMAIN FOR THURSDAY HIGHS...DEPENDING IF PRECIP RETURNS EARLY OR LATE THURSDAY. WE WENT WITH THE PREMISE THAT EVEN WITH REDUCED SUNSHINE...ENOUGH BURN-THROUGH HEATING SHOULD PUSH HIGHS INTO THE LOWER 70S. THE PASSAGE OF THE COLD FRONT WILL BRING AN AIRMASS CHANGE FOR FRIDAY AND THROUGH NEXT WEEKEND. TEMPS WILL LIKELY DIP BELOW NORMAL FOR THE WEEKEND AND POSSIBLY INTO EARLY NEXT WEEK AS A DEEP TROUGH BECOME ESTABLISHED IN THE MIDWEST ONCE AGAIN. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
507 PM CDT THU OCT 18 2012 .DISCUSSION... 341 PM CDT MAIN FORECAST CONCERNS CONTINUE WITH SHOWERS/POSSIBLE THUNDER THIS AFTERNOON...AND SHOWERS TO PERSIST THROUGH FRIDAY. LATEST WATER VAPOR IMAGERY SHOWING LARGE CLOSED UPPER LEVEL SYSTEM OVER THE MIDWEST THIS AFTERNOON...WITH SEVERAL STRONG MID LEVEL FEATURES WRAPPING AROUND THIS SYSTEM. THIS FORCING IN THE PRESENCE OF STEEP LAPSE RATES...PER AMDAR SOUNDINGS AND RAP ANALYSIS...HAS ALLOWED SHOWERS TO BLOSSOM ACROSS NORTHERN ILLINOIS. ISOLATED CONVECTIVE ELEMENTS HAVE ALSO BEGUN TO DEVELOP OUT AHEAD OF THIS MAIN PRECIP SHIELD ACROSS NORTHEAST ILLINOIS AND NORTHWEST INDIANA WHERE STEEPER LAPSE RATES CURRENTLY RESIDE. EXPECT THESE CONVECTIVE ELEMENTS TO BE THE MORE NORM THROUGH THE REMAINDER OF THE AFTERNOON AS MAIN PRECIP SHIELD CONTINUES TO SHIFT ACROSS THE AREA. ITS IN THESE CONVECTIVE ELEMENTS THAT HEAVIER SHOWERS AND LOWER VIS COULD OCCUR...AND ALSO WHERE THE POSSIBILITY OF THUNDER/SMALL HAIL STILL MAY OCCUR. UPPER LEVEL LOW WILL CONTINUE TO SLOWLY MEANDER TO THE EAST OVERNIGHT...WITH PRECIP EXPECTED TO PERSIST FOR MUCH OF THE CWA TONIGHT. ALTHOUGH WITH MID LEVEL FEATURES/FORCING SHIFTING EASTWARD TONIGHT...MAIN AXIS OF PRECIP SHOULD ALSO SHIFT. NEVERTHELESS...EXPECT AT LEAST LIGHT SHOWERS OR DRIZZLE TO CONTINUE OVERNIGHT ACROSS THE ENTIRE CWA WITH TEMPS SLOWLY LOWERING TO AROUND 40 ACROSS NORTHERN ILLINOIS AND THE LOWER 40S FOR THE REMAINDER OF THE CWA...AS EXPANSIVE CLOUD SHIELD REMAINS OVERHEAD. UPPER LEVEL LOW CENTER AND COLDEST TEMPS WILL BE OVERHEAD ON FRIDAY...WITH A SIMILAR SETUP EXPECTED ONCE AGAIN. SHOWERS WILL BE POSSIBLE ALONG WITH A SLIGHT CHANCE FOR THUNDERSTORMS/SMALL HAIL ONCE AGAIN IN THE AFTERNOON...WHEN LAPSE RATES ARE ONCE AGAIN EXPECTED TO BE THE STEEPEST. TEMPS WILL STRUGGLE TO CLIMB MUCH AS THIS CLOUD SHIELD WILL REMAIN OVERHEAD...WITH TEMPS IN THE UPPER 40S TO AROUND 50 EXPECTED. GUIDANCE IN FAIR AGREEMENT WITH TAKING THIS UPPER LEVEL LOW EAST OF THE AREA BY FRIDAY NIGHT AND EARLY SATURDAY MORNING. SO CONTINUED TREND OF LOWERING POPS THROUGH FRIDAY NIGHT BUT WITH THESE SYSTEMS GENERALLY MOVING SLOWER THAN MODEL GUIDANCE...WASNT TOO AGGRESSIVE WITH LOWERING THE POPS AS STRAY SHOWERS MAY LINGERING WITH CYCLONIC FLOW STILL IN PLACE. AS UPPER LEVEL SYSTEM CONTINUES TO DRIFT EAST ON SATURDAY...HEIGHT RISES ON THE BACKSIDE OF THIS SYSTEM WILL SET THE STAGE FOR A PERIOD OF UPPER LEVEL RIDGING. WHAT THIS WILL MEAN FOR THE REMAINDER OF THE WEEKEND WILL BE CLEARING SKIES AND QUIET WEATHER WITH AN INCREASE IN TEMPS. EXPECT WINDS TO FLOP BACK TO THE SOUTH/SOUTHWEST LATE SATURDAY WITH WAA USHERING IN SOME WARMTH ACROSS THE REGION. THIS WAA AND SUNNY SKIES WILL HELP TEMPS RISE WITH FORECAST HIGHS EXPECTED TO BE IN THE UPPER 60S TO LOW 70S ON SUNDAY. THIS WARMTH WILL CONTINUE ON MONDAY WITH A SLIGHT INCREASE IN TEMPS...AS THEY RISE TO THE LOW TO MID 70S. ALTHOUGH WITH THE RIDGE AXIS OVERHEAD...THIS WILL BRING A SETUP FOR STEERING FLOW TO BRING ABOUT SOME MID LEVEL ENERGY AND ACTIVE WEATHER FOR NEXT WEEK. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 22Z... * GUSTY SOUTH WINDS THROUGH EARLY THIS EVENING. * SHRA THROUGH THIS EVENING. * TIMING OF 1500 FT MVFR CIGS THIS EVENING. * POTENTIAL FOR IFR CIGS OVERNIGHT INTO FRIDAY MORNING. RC/KB //DISCUSSION...UPDATED 18Z... MULTIPLE CONCERNS THIS FORECAST PERIOD WITH SURFACE AND UPPER LEVEL LOW PRESSURE DROPPING SOUTHEASTWARD OVER THE TERMINALS. PRECIP...LATEST RADAR SHOWS SHRA BLOSSOMING OVER EASTERN IA AND NW IL AND THESE WILL CONTINUE TO BLOSSOM AND MOVE ENE OVER THE TERMINALS THRU EARLY EVENING. STILL CANT COMPLETELY RULE OUT SOME SMALL HAIL IN ANY STRONGER SHRA. TONIGHT...THERE IS A LOSS OF VERTICAL MOTION...SO ANY PRECIP SHOULD TREND TO VERY LIGHT SHRA OR SPOTTY DZ UNTIL A POSSIBLE RAMPING UP OF SHRA ACTIVITY EARLY- MID FRI AFTERNOON AS A MID LEVEL DISTURBANCE ROTATES INTO AREA. CIG/VSBY...USED LOW LEVEL RH MODEL PROGS AND REGIONAL OBS TO CONTINUE TO FAVOR MVFR CIGS MID-LATE THIS AFTERNOON...THOUGH TIMING IS A BIT UNCERTAIN ESPECIALLY FOR EASTERN TERMINALS. WITH COLD LOW PRESSURE OVERHEAD TONIGHT...CIGS EXPECTED TO LOWER FROM MVFR TO POTENTIALLY IFR. IF IFR OCCURS...PER MODEL SOUNDINGS...IT IS LIKELY TO CONTINUE UNTIL LATE MORNING FRIDAY...WITH GRADUAL IMPROVEMENT THEREAFTER. VSBY MAY DROP TO MVFR IN SHRA ACTIVITY LATE THIS AFTERNOON...SO WILL NEED TO MONITOR FOR NEXT UPDATE. MVFR VSBY IS EXPECTED TO OCCUR WITH MORE STAGNANT CONDITIONS OVERNIGHT INTO FRI MORNING. WINDS...SOUTH-SOUTHWEST WINDS WILL REMAIN GUSTY...WITH SOME GUSTS AT OR A BIT ABOVE 25 KT STILL POSSIBLE THROUGH LATE AFTERNOON/EARLY EVE. GUSTS WILL REMAIN IN 20 KT RANGE THROUGH THE EVENING AS WINDS TURN MORE SOUTHERLY. THEN WITH LOW PRESSURE MOVING OVERHEAD...WINDS WILL BECOME MUCH LIGHTER AND TURN FROM SOUTHWESTERLY OVERNIGHT INTO EARLY FRIDAY TO WESTERLY OR NORTHWESTERLY BY LATE MORNING OR EARLY AFTERNOON ON FRIDAY. RC //ORD AND MDW CONFIDENCE...UPDATED 22Z... * MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION AND WIND GUST TRENDS. * MEDIUM CONFIDENCE IN CIGS LOWERING TO AROUND 1500 FT THIS EVENING AND TIMING OF LOWERING...WITH LOW-MEDIUM CONFIDENCE IN CIGS LOWERING TO IFR OVERNIGHT. * MEDIUM-HIGH CONFIDENCE IN SHRA TRENDS THROUGH THIS EVENING. * MEDIUM CONFIDENCE IN VSBY TRENDS...WITH PRIMARILY VFR VIS EXPECTED IN THE SHRA. RC/KJB //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... * FRIDAY NIGHT...RAIN SHOWERS LIKELY. MVFR CIGS/VIS POSSIBLE. * SATURDAY AND SUNDAY...VFR. WX NIL. * MONDAY THROUGH WEDNESDAY...CHANCE OF TSRA/SHRA. KREIN/RC && .MARINE... 253 PM CDT A LARGE UPPER LEVEL LOW WILL CONTINUE TO SPIN OVER OVER SOUTHERN WISCONSIN AND SOUTHERN LAKE MICHIGAN TONIGHT AND FRIDAY BEFORE GRADUALLY SHIFTING OFF TO THE EAST INTO SATURDAY. ONE AREA OF LOW PRESSURE CONTINUES TO SPIN OVER THE ARROWHEAD OF MINNESOTA WITH A SECONDARY CIRCULATION OVER WEST CENTRAL WISCONSIN. THE TWO LOWS WILL MERGE AND WEAKEN TONIGHT AND THEN MOVE EASTWARD ACROSS SOUTHERN LAKE MICHIGAN FRIDAY AND FRIDAY NIGHT. IN THE MEANTIME...THE PRESSURE GRADIENT REMAINS STRONG LEADING TO 30 KT SOUTH TO SOUTHWEST WINDS ACROSS THE LAKE...WITH SOME 35 KT GALES OCCURRING AT TIMES LATE THIS AFTERNOON AND POSSIBLY EARLY THIS EVENING. SPEEDS LOOK TO REMAIN STEADY THROUGH THE EVENING BUT THEN BEGIN TO SLOWLY DIMINISH AS THE LOW BROADENS AND WEAKENS RESULTING IN A WEAKER PRESSURE GRADIENT. THE DOWNWARD TREND SHOULD CONTINUE FRIDAY WITH WIND DIRECTION BECOMING MORE COMPLEX AS THE LOW CROSSES THE SOUTHERN PART OF THE LAKE. SOUTHWEST WINDS WILL OCCUR TO THE SOUTH OF THE LOW WHILE WINDS TURN SOUTHEAST...THEN EAST...THEN NORTHEAST NORTH OF THE LOW ACROSS THE NORTHERN HALF TO TWO-THIRDS OF THE LAKE FRIDAY. ONCE THE LOW SHIFTS EAST FRIDAY EVENING NORTH TO NORTHWEST WINDS WILL TAKE OVER WITH SOME MODEST INCREASE IN SPEEDS LIKELY AS THE PRESSURE GRADIENT RECOVERS BUT THE LOW ITSELF WILL REMAIN IN A WEAKENED STATE. IN ADDITION...WITH THE UPPER LOW PRESENT AND COLDER AIR ACROSS THE LAKE...THERE WILL BE A GOOD CHANCE FOR WATERSPOUTS THROUGH FRIDAY...WITH A FEW THUNDERSTORMS POSSIBLE AS WELL. THE NORTHWEST WINDS WILL CONTINUE INTO INTO SATURDAY BEFORE TURNING WESTERLY THEN SOUTHWESTERLY SATURDAY EVENING AS A RIDGE OF HIGH PRESSURE BUILDS FROM SOUTHERN LAKE MICHIGAN INTO WESTERN WISCONSIN. THE RIDGE SHIFTS EAST MONDAY ALLOWING WINDS TO TURN SOUTHEASTERLY AS LOW PRESSURE SPREADS ACROSS THE CENTRAL AND NORTHERN PLAINS FOR THE MIDDLE PART OF THE WEEK. SOUTH TO SOUTHEAST WINDS WILL LIKELY INCREASE AS THE PRESSURE GRADIENT STRENGTHENS AS THE LOW TRACKS NORTHEAST ACROSS THE UPPER MISSISSIPPI RIVER VALLEY AND LAKE SUPERIOR. BEYOND THAT A FRONTAL BOUNDARY SHOULD CROSS THE LAKE AND BRING A RETURN TO NORTHERLY WINDS FOR LATE WEEK. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 5 AM FRIDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
344 PM CDT THU OCT 18 2012 .DISCUSSION... 341 PM CDT MAIN FORECAST CONCERNS CONTINUE WITH SHOWERS/POSSIBLE THUNDER THIS AFTERNOON...AND SHOWERS TO PERSIST THROUGH FRIDAY. LATEST WATER VAPOR IMAGERY SHOWING LARGE CLOSED UPPER LEVEL SYSTEM OVER THE MIDWEST THIS AFTERNOON...WITH SEVERAL STRONG MID LEVEL FEATURES WRAPPING AROUND THIS SYSTEM. THIS FORCING IN THE PRESENCE OF STEEP LAPSE RATES...PER AMDAR SOUNDINGS AND RAP ANALYSIS...HAS ALLOWED SHOWERS TO BLOSSOM ACROSS NORTHERN ILLINOIS. ISOLATED CONVECTIVE ELEMENTS HAVE ALSO BEGUN TO DEVELOP OUT AHEAD OF THIS MAIN PRECIP SHIELD ACROSS NORTHEAST ILLINOIS AND NORTHWEST INDIANA WHERE STEEPER LAPSE RATES CURRENTLY RESIDE. EXPECT THESE CONVECTIVE ELEMENTS TO BE THE MORE NORM THROUGH THE REMAINDER OF THE AFTERNOON AS MAIN PRECIP SHIELD CONTINUES TO SHIFT ACROSS THE AREA. ITS IN THESE CONVECTIVE ELEMENTS THAT HEAVIER SHOWERS AND LOWER VIS COULD OCCUR...AND ALSO WHERE THE POSSIBILITY OF THUNDER/SMALL HAIL STILL MAY OCCUR. UPPER LEVEL LOW WILL CONTINUE TO SLOWLY MEANDER TO THE EAST OVERNIGHT...WITH PRECIP EXPECTED TO PERSIST FOR MUCH OF THE CWA TONIGHT. ALTHOUGH WITH MID LEVEL FEATURES/FORCING SHIFTING EASTWARD TONIGHT...MAIN AXIS OF PRECIP SHOULD ALSO SHIFT. NEVERTHELESS...EXPECT AT LEAST LIGHT SHOWERS OR DRIZZLE TO CONTINUE OVERNIGHT ACROSS THE ENTIRE CWA WITH TEMPS SLOWLY LOWERING TO AROUND 40 ACROSS NORTHERN ILLINOIS AND THE LOWER 40S FOR THE REMAINDER OF THE CWA...AS EXPANSIVE CLOUD SHIELD REMAINS OVERHEAD. UPPER LEVEL LOW CENTER AND COLDEST TEMPS WILL BE OVERHEAD ON FRIDAY...WITH A SIMILAR SETUP EXPECTED ONCE AGAIN. SHOWERS WILL BE POSSIBLE ALONG WITH A SLIGHT CHANCE FOR THUNDERSTORMS/SMALL HAIL ONCE AGAIN IN THE AFTERNOON...WHEN LAPSE RATES ARE ONCE AGAIN EXPECTED TO BE THE STEEPEST. TEMPS WILL STRUGGLE TO CLIMB MUCH AS THIS CLOUD SHIELD WILL REMAIN OVERHEAD...WITH TEMPS IN THE UPPER 40S TO AROUND 50 EXPECTED. GUIDANCE IN FAIR AGREEMENT WITH TAKING THIS UPPER LEVEL LOW EAST OF THE AREA BY FRIDAY NIGHT AND EARLY SATURDAY MORNING. SO CONTINUED TREND OF LOWERING POPS THROUGH FRIDAY NIGHT BUT WITH THESE SYSTEMS GENERALLY MOVING SLOWER THAN MODEL GUIDANCE...WASNT TOO AGGRESSIVE WITH LOWERING THE POPS AS STRAY SHOWERS MAY LINGERING WITH CYCLONIC FLOW STILL IN PLACE. AS UPPER LEVEL SYSTEM CONTINUES TO DRIFT EAST ON SATURDAY...HEIGHT RISES ON THE BACKSIDE OF THIS SYSTEM WILL SET THE STAGE FOR A PERIOD OF UPPER LEVEL RIDGING. WHAT THIS WILL MEAN FOR THE REMAINDER OF THE WEEKEND WILL BE CLEARING SKIES AND QUIET WEATHER WITH AN INCREASE IN TEMPS. EXPECT WINDS TO FLOP BACK TO THE SOUTH/SOUTHWEST LATE SATURDAY WITH WAA USHERING IN SOME WARMTH ACROSS THE REGION. THIS WAA AND SUNNY SKIES WILL HELP TEMPS RISE WITH FORECAST HIGHS EXPECTED TO BE IN THE UPPER 60S TO LOW 70S ON SUNDAY. THIS WARMTH WILL CONTINUE ON MONDAY WITH A SLIGHT INCREASE IN TEMPS...AS THEY RISE TO THE LOW TO MID 70S. ALTHOUGH WITH THE RIDGE AXIS OVERHEAD...THIS WILL BRING A SETUP FOR STEERING FLOW TO BRING ABOUT SOME MID LEVEL ENERGY AND ACTIVE WEATHER FOR NEXT WEEK. RODRIGUEZ && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * WINDS 200-230 DEG WITH GUSTS UP TO 25 KT+...WITH ONLY SPORADIC GUSTS TO 30 KT...GRADUALLY TURNING TO 190-220 DEG LATER THIS AFTERNOON AND 170-200 DEG THIS EVENING...WITH GUSTS TO AROUND 20 KT THROUGH ABOUT 06Z. * SHRA THROUGH THIS EVENING. * TIMING OF 1500 FT MVFR CIGS THIS EVENING. * POTENTIAL FOR IFR CIGS OVERNIGHT INTO FRIDAY MORNING. RC //DISCUSSION...UPDATED 18Z... MULTIPLE CONCERNS THIS FORECAST PERIOD WITH SURFACE AND UPPER LEVEL LOW PRESSURE DROPPING SOUTHEASTWARD OVER THE TERMINALS. PRECIP...LATEST RADAR SHOWS SHRA BLOSSOMING OVER EASTERN IA AND NW IL AND THESE WILL CONTINUE TO BLOSSOM AND MOVE ENE OVER THE TERMINALS THRU EARLY EVENING. STILL CANT COMPLETELY RULE OUT SOME SMALL HAIL IN ANY STRONGER SHRA. TONIGHT...THERE IS A LOSS OF VERTICAL MOTION...SO ANY PRECIP SHOULD TREND TO VERY LIGHT SHRA OR SPOTTY DZ UNTIL A POSSIBLE RAMPING UP OF SHRA ACTIVITY EARLY- MID FRI AFTERNOON AS A MID LEVEL DISTURBANCE ROTATES INTO AREA. CIG/VSBY...USED LOW LEVEL RH MODEL PROGS AND REGIONAL OBS TO CONTINUE TO FAVOR MVFR CIGS MID-LATE THIS AFTERNOON...THOUGH TIMING IS A BIT UNCERTAIN ESPECIALLY FOR EASTERN TERMINALS. WITH COLD LOW PRESSURE OVERHEAD TONIGHT...CIGS EXPECTED TO LOWER FROM MVFR TO POTENTIALLY IFR. IF IFR OCCURS...PER MODEL SOUNDINGS...IT IS LIKELY TO CONTINUE UNTIL LATE MORNING FRIDAY...WITH GRADUAL IMPROVEMENT THEREAFTER. VSBY MAY DROP TO MVFR IN SHRA ACTIVITY LATE THIS AFTERNOON...SO WILL NEED TO MONITOR FOR NEXT UPDATE. MVFR VSBY IS EXPECTED TO OCCUR WITH MORE STAGNANT CONDITIONS OVERNIGHT INTO FRI MORNING. WINDS...SOUTH-SOUTHWEST WINDS WILL REMAIN GUSTY...WITH SOME GUSTS AT OR A BIT ABOVE 25 KT STILL POSSIBLE THROUGH LATE AFTERNOON/EARLY EVE. GUSTS WILL REMAIN IN 20 KT RANGE THROUGH THE EVENING AS WINDS TURN MORE SOUTHERLY. THEN WITH LOW PRESSURE MOVING OVERHEAD...WINDS WILL BECOME MUCH LIGHTER AND TURN FROM SOUTHWESTERLY OVERNIGHT INTO EARLY FRIDAY TO WESTERLY OR NORTHWESTERLY BY LATE MORNING OR EARLY AFTERNOON ON FRIDAY. RC //ORD AND MDW CONFIDENCE...UPDATED 20Z... * MEDIUM-HIGH CONFIDENCE IN WIND DIRECTION AND WIND GUST TRENDS. * HIGH CONFIDENCE IN CIGS LOWERING TO MVFR AROUND 2500 FT MID-LATE AFTERNOON...MEDIUM CONFIDENCE IN EXACT TIMING AND CIG BASE HEIGHT. * MEDIUM CONFIDENCE IN CIGS LOWERING TO AROUND 1500 FT THIS EVENING AND TIMING OF LOWERING...WITH LOW-MEDIUM CONFIDENCE IN CIGS LOWERING TO IFR OVERNIGHT. * MEDIUM-HIGH CONFIDENCE IN SHRA TRENDS THROUGH THIS EVENING. * MEDIUM CONFIDENCE IN VSBY TRENDS...WITH MVFR VSBY POSSIBLE IN SHRA THIS AFTERNOON. * LOW CONFIDENCE IN SMALL HAIL OCCURRING AT THE TERMINALS. RC //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... * FRIDAY NIGHT...RAIN SHOWERS LIKELY. MVFR CIGS/VIS POSSIBLE. * SATURDAY AND SUNDAY...VFR. WX NIL. * MONDAY THROUGH WEDNESDAY...CHANCE OF TSRA/SHRA. KREIN/RC && .MARINE... 253 PM CDT A LARGE UPPER LEVEL LOW WILL CONTINUE TO SPIN OVER OVER SOUTHERN WISCONSIN AND SOUTHERN LAKE MICHIGAN TONIGHT AND FRIDAY BEFORE GRADUALLY SHIFTING OFF TO THE EAST INTO SATURDAY. ONE AREA OF LOW PRESSURE CONTINUES TO SPIN OVER THE ARROWHEAD OF MINNESOTA WITH A SECONDARY CIRCULATION OVER WEST CENTRAL WISCONSIN. THE TWO LOWS WILL MERGE AND WEAKEN TONIGHT AND THEN MOVE EASTWARD ACROSS SOUTHERN LAKE MICHIGAN FRIDAY AND FRIDAY NIGHT. IN THE MEANTIME...THE PRESSURE GRADIENT REMAINS STRONG LEADING TO 30 KT SOUTH TO SOUTHWEST WINDS ACROSS THE LAKE...WITH SOME 35 KT GALES OCCURRING AT TIMES LATE THIS AFTERNOON AND POSSIBLY EARLY THIS EVENING. SPEEDS LOOK TO REMAIN STEADY THROUGH THE EVENING BUT THEN BEGIN TO SLOWLY DIMINISH AS THE LOW BROADENS AND WEAKENS RESULTING IN A WEAKER PRESSURE GRADIENT. THE DOWNWARD TREND SHOULD CONTINUE FRIDAY WITH WIND DIRECTION BECOMING MORE COMPLEX AS THE LOW CROSSES THE SOUTHERN PART OF THE LAKE. SOUTHWEST WINDS WILL OCCUR TO THE SOUTH OF THE LOW WHILE WINDS TURN SOUTHEAST...THEN EAST...THEN NORTHEAST NORTH OF THE LOW ACROSS THE NORTHERN HALF TO TWO-THIRDS OF THE LAKE FRIDAY. ONCE THE LOW SHIFTS EAST FRIDAY EVENING NORTH TO NORTHWEST WINDS WILL TAKE OVER WITH SOME MODEST INCREASE IN SPEEDS LIKELY AS THE PRESSURE GRADIENT RECOVERS BUT THE LOW ITSELF WILL REMAIN IN A WEAKENED STATE. IN ADDITION...WITH THE UPPER LOW PRESENT AND COLDER AIR ACROSS THE LAKE...THERE WILL BE A GOOD CHANCE FOR WATERSPOUTS THROUGH FRIDAY...WITH A FEW THUNDERSTORMS POSSIBLE AS WELL. THE NORTHWEST WINDS WILL CONTINUE INTO INTO SATURDAY BEFORE TURNING WESTERLY THEN SOUTHWESTERLY SATURDAY EVENING AS A RIDGE OF HIGH PRESSURE BUILDS FROM SOUTHERN LAKE MICHIGAN INTO WESTERN WISCONSIN. THE RIDGE SHIFTS EAST MONDAY ALLOWING WINDS TO TURN SOUTHEASTERLY AS LOW PRESSURE SPREADS ACROSS THE CENTRAL AND NORTHERN PLAINS FOR THE MIDDLE PART OF THE WEEK. SOUTH TO SOUTHEAST WINDS WILL LIKELY INCREASE AS THE PRESSURE GRADIENT STRENGTHENS AS THE LOW TRACKS NORTHEAST ACROSS THE UPPER MISSISSIPPI RIVER VALLEY AND LAKE SUPERIOR. BEYOND THAT A FRONTAL BOUNDARY SHOULD CROSS THE LAKE AND BRING A RETURN TO NORTHERLY WINDS FOR LATE WEEK. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 5 AM FRIDAY. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
800 PM EDT FRI OCT 19 2012 .AVIATION... /00 UTC TAFS/ STACKED LWR/MID TROPOSPHERIC SYSTEM ACRS FAR SERN LAKE MICHIGAN/KLWA TO BEGIN GRDL EWD ACCELERATION AFT 06 UTC SAT,..AS UPSTREAM NRN IL SHORTWAVE CONTS EMBEDDED ROTATION INTO NRN IN PER 19/18 NAM AND 19/21 RAP CONSENSUS. MOIST/PERTURBED BLYR FLOW SHOULD PROMOTE VAST EXPANSE OF MVFR CIGS ACRS GRTLKS OVRNGHT...LKLY SETTLING INTO LWR INTO UPR END OF IFR MET RANGE TOWARD DAYBREAK/PEAK COOLING. THEREAFTER...CONCURRENCE WITH SHORT TERM FCSTS THAT MARGINAL LAKE INDUCED THERMAL INSTABILITY TO LIMIT DURATION OF MVFR CIGS... YIELDING TO VFR MET CONDS BY MID AFTN. && .SHORT TERM... SHORT WAVE MOVING AROUND BASE OF UPPER LOW GENERATING ADDITIONAL AREA OF SHOWERS THIS AFTERNOON ACROSS MOST OF CWA. SOME CONVECTIVE DEVELOPMENT CLOSE TO LAKE IN AREA OF ENHANCED CONVERGENCE. COULD BE A FEW RUMBLES OF THUNDER AND EVEN SOME SMALL GRAUPEL BUT NO REPORTS OR INDICATIONS AS OF YET SO WILL CONTINUE WITH SHOWER WORDING. SUBSIDENCE IN WAKE OF THIS SHORT WAVE WILL HELP SCATTER OUT THE PCPN BUT YET ANOTHER WEAKER SHORT WAVE WILL APPROACH THIS EVENING AND COULD HELP DEVELOP ANOTHER BATCH OF RAIN. FLOW WILL BECOME MORE NORTHWEST BEHIND THE WAVE THIS EVENING AND UPPER LOW WILL BE SHIFTING EAST OF LAKE MICHIGAN. THIS WILL SET THE STAGE FOR A PERIOD OF LAKE ENHANCED AND LAKE EFFECT SHOWERS INTO SATURDAY MORNING. DELTA T VALUES LOOK TO ONLY BE IN MID TEENS AT BEST WITH MID LAKE TEMPS IN THE MID 50S AND 850MB TEMPS AROUND 0C. ABUNDANT SYNOPTIC MOISTURE AND LIFT/CYCLONIC FLOW AROUND UPPER LOW SHOULD AID IN LAKE DEVELOPMENT OVERNIGHT. TRAJECTORIES AND LACK OF SIGNIFICANT INVERSION SHOULD AID SHOWERS WITH DECENT INLAND PENETRATION. HAVE INCREASED POPS NORTHWEST TO CATEGORICAL OVERNIGHT AND LIKELY FAR NORTHWEST EARLY ON SATURDAY BEFORE DRIER AIR MOVES IN. CLOUDS TO LIKELY LINGER INTO LATE AFTERNOON AND EARLY EVENING AS RECENT EVENTS HAVE BEEN SLOW TO CLEAR. THIS WILL ALSO KEEP TEMPS A FEW DEGREES SATURDAY. ADJUSTED GRIDS FOR CLEARING SOUTHWEST IN AFTERNOON AND MID EVENING FAR NORTHEAST. CLEARING SKIES AND LIGHT WINDS SAT NIGHT WILL ALLOW FOR GOOD RADIATIONAL COOLING. LOWERED TEMPS SAT NIGHT BY SEVERAL DEGREES WITH ADJUSTMENTS FROM BIAS CORRECTED AND CONSALL GRIDS. && .LONG TERM...SUNDAY THROUGH FRIDAY RIDGING AT THE SFC AND ALOFT SUNDAY INTO SUNDAY NIGHT WILL RESULT IN MAINLY CLEAR SKIES AND WARMER TEMPS. PROGGED MIXING TO NEAR 900/875 MB AND FULL SUN SHOULD ALLOW AFTN HIGHS TO REACH THE LOW/MID 60S AS 925 MB TEMPS WARM TO NEAR 11C BY LATE IN THE DAY. LOWERED SUNDAY NIGHT MINS SEVERAL DEGREES, ESPECIALLY EAST, WHERE FULL DECOUPLING IS EXPECTED UNDER LINGERING RIDGE/CLEAR SKIES. 12Z GLOBAL MODELS REMAINED RELATIVELY CONSISTENT WITH THE OVERALL SYNOPTIC PATTERN NEXT WEEK AS A BROAD UPPER LEVEL TROUGH DIGS INTO THE WESTERN CONUS EARLY/MID WEEK...WITH A STRONG UPPER JET AND SHORTWAVE ENERGY ROUNDING THE BASE OF THE TROUGH EVENTUALLY CARVING OUT A MORE SIGNIFICANT CYCLONE ACROSS THE NORTHERN PLAINS/SC CANADA BY LATE IN THE WEEK. THIS WILL PLACE THE MIDWEST AND GREAT LAKES IN MILD SOUTHWEST FLOW AS LOW LVL THERMAL RIDGE SETTLES INTO THE SOUTHERN GREAT LAKES ON THE NORTHWEST FRINGE OF SE CONUS LOW LVL ANTICYCLONE. LATEST ALLBLEND GUIDANCE GENERALLY HAS TEMPS BTW 10 AND 15 DEGREES ABOVE NORMAL FOR MUCH OF NEXT WEEK. AS FOR RAINFALL CHANCES...RETAINED CHC POPS FOR SHOWERS/ISO THUNDER MONDAY AFTERNOON THROUGH TUESDAY EVENING. THIS ACTIVITY WILL BE TIED TO THE INITIAL THETA-E SURGE AHEAD OF A SHEARING/WEAK LEAD SHORTWAVE CURRENTLY JUST OFF THE BAJA CA COAST. BEST CHANCES WILL BE ACROSS OUR NW INDIANA AND SW LOWER MI ZONES CLOSER TO A FRONTAL BOUNDARY THAT MODELS GENERALLY KEEP JUST NORTH OF THE IWX CWA. ASSOCIATED CLOUD COVER AND PCPN MAY HOLD HIGH TEMPS LOWER THAN CURRENTLY GRIDDED UP ACROSS THE NORTH BOTH MONDAY AND TUESDAY. THE FRONTAL BOUNDARY SHOULD LIFT EVEN FARTHER NORTH OF THE AREA WEDNESDAY INTO THURSDAY MORNING IN RESPONSE TO PLAINS HEIGHT FALLS AND DEEPENING SOUTHWESTERLY FLOW. MODEL THERMAL PROFILES SUGGESTING MID 70S TO LOW 80S POSSIBLE WEDNESDAY AND THURSDAY IF FULL SUN AND PROGGED DEEPER MIXING COMES TO FRUITION. HELD CLOSE, YET STILL WARMER THAN, LATEST ALLBLEND GUIDANCE WITH MORE CONSERVATIVE LOW/MID 70S FOR HIGHS GIVEN UNCERTAINTIES WRT TIMING AND CLOUD COVER. THE ABOVE MENTIONED POTENT NC CONUS SYSTEM STILL LOOKS TO FORCE A WEAKENING COLD/OCCLUDED FRONT THROUGH THE AREA LATE THURSDAY AFTN/THURSDAY NIGHT PER A MODEL CONSENSUS. OPTED TO RETAIN LOW CHC POPS DURING THIS TIME WITH TEMPS RETURNING CLOSER TO SEASONAL NORMS BY FRIDAY. && .AVIATION... NEXT IN A SERIES OF SHORT WAVES ROUNDING BASE OF STACKED UPPER LOW. RAIN WAS INCREASING JUST TO SOUTH AND WEST OF TAF SITES AT ISSUANCE IN ADVANCE OF THIS WAVE. EXPECT RAIN TO INCREASE AT TAF SITES ONCE AGAIN IN NEXT HOUR. IFR CONDITIONS NOTED UPSTREAM OF KSBN AT KVPZ AND KRZL WITH HEAVIER PCPN. ONLY MVFR RESTRICTIONS NOTED SO FAR SOUTHWEST OF KFWA. TAFS HAVE FOLLOWED THIS REASONING FOR NOW. EXPECT PCPN TO TAPER OFF LATER THIS AFTERNOON/EARLY EVENING AS THIS WAVE PASSES. ONLY SCATTERED SHOWERS THEN EXPECTED OUTSIDE OF LAKE EFFECT AREA BUT ONE LAST WEAKER SHORT WAVE COULD SPARK ADDITIONAL DEVELOPMENT THIS EVENING. FLOW TURNS NORTHWEST TONIGHT WITH DELTA T VALUES IN MID TEENS WITH AMPLE SYNOPTIC MOISTURE SO EXPECT LAKE EFFECT RAIN SHOWERS TO DEVELOP. TRAJECTORIES FAVOR KSBN WITH ANY RESIDUAL SHOWERS IN LINE FOR KFWA. EXPECT MAINLY MVFR CIGS AT KFWA BUT A FEW STRAY SHOWERS ALSO POSSIBLE. LITTLE IMPROVEMENT AT END OF THIS PERIOD WITH CIGS. MORE SUBSTANTIAL IMPROVEMENT AND CLEARING WILL OCCUR LATE SAT AFTERNOON AND SAT EVENING. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY FROM 2 AM TO 5 PM EDT SATURDAY FOR LMZ043- 046. && $$ SHORT TERM...LASHLEY LONG TERM...STEINWEDEL AVIATION...MURPHY
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
618 PM CDT FRI OCT 19 2012 .AVIATION... THE LAST BAND OF RAIN ROTATING AROUND AN UPPER LEVEL LOW WILL EXIT THE LOCAL AREA THROUGH 8 PM...WITH GENERALLY VFR WEATHER IN ITS WAKE FOR THE OVERNIGHT HOURS. SOME BREAKS IN THE OVERCAST 3500 FT TO 5000 FT CLOUD LAYER MAY OCCUR OVERNIGHT...RESULTING IN A CHANCE FOR MVFR VISIBILITIES AROUND 5 MILES. SHOULD CLEAR SKIES OCCUR...IFR VISIBILITIES ARE A POSSIBILITY TOWARD DAWN. SATURDAY...CLEAR SKIES...LIGHT WEST WINDS AND UNLIMITED VISIBILITIES ARE EXPECTED ALL DAY WITH HIGH PRESSURE IN CONTROL. ERVIN && .PREV DISCUSSION... /ISSUED 258 PM CDT FRI OCT 19 2012/ SYNOPSIS... 12Z UA ANALYSIS HAS THE UPPER LOW OVER WISCONSIN WITH NUMEROUS TROFS FROM THE OHIO VALLEY BACK INTO THE PLAINS AND UPPER MIDWEST. SATELLITE/RADAR TRENDS THROUGH MID AFTERNOON SHOWS THE INITIAL SUBSIDENCE HAS FILLED BACK IN WITH DIURNAL CLOUDS. A VORT MAX ROTATING SOUTHEAST OUT OF MINNESOTA IS HELPING TO GENERATE NEW SHOWERS/SPRINKLES. 18Z SFC ANALYSIS HAS A LOW OVER SOUTHERN LAKE MICHIGAN WEST OF KBIV. NUMEROUS TROFS RAN FROM THE LOW FROM THE LOWER OHIO VALLEY BACK UP THROUGH WISCONSIN AND MINNESOTA. DEW POINTS WERE IN THE 30S AND 40S ACROSS THE MIDWEST. SHORT TERM...LATE THIS AFTERNOON THROUGH SATURDAY... THE VORT MAX HELPING TO GENERATE THE SHRA ACTIVITY ACROSS THE CWFA IS FURTHER TO THE NORTH/EAST THAN WHAT THE RAP WAS SUGGESTING EARLIER TODAY. BASED ON THE CURRENT AND EXTRAPOLATED POSITION OF THE SHRA ACTIVITY...THERE SHOULD BE AN AREA OF CONCENTRATED SHOWERS BETWEEN KDBQ/KALO TO THE SOUTHEAST LATE THIS AFTERNOON. SAID ACTIVITY WILL CONTINUE INTO THE EARLY EVENING FROM NORTHEAST OF KIOW DOWN TOWARDS KGBG BEFORE DISSIPATING LATER THIS EVENING. AROUND THIS BAND OF CONCENTRATED SHRA ACTIVITY ISOLATED TO LOW END SCATTERED DIURNAL SHRA WILL BE SEEN THAT DISSIPATE SHORTLY AFTER SUNSET. BASED ON THE LUMPY NATURE OF THE CLOUDS ON SATELLITE...SUBSIDENCE AND THE SETTING SUN WILL RESULT IN A CLEARING POCKET THAT DEVELOPS ACROSS MN AND WESTERN WISCONSIN THAT SHOULD BEGIN ROTATING SOUTH AND THEN SOUTHEAST ACROSS THE CWFA BY LATE EVENING WITH PARTIAL CLEARING CONTINUING OVERNIGHT. WINDS WILL DIMINISH BUT NOT AS MUCH AS LAST NIGHT. HOWEVER...IN SHELTERED AREAS AND SOME RIVER VALLEYS THERE IS A POTENTIAL FOR PATCHY FOG TO DEVELOP LATE TONIGHT. IF FOG DEVELOPS LATE TONIGHT IT WILL LINGER INTO EARLY SATURDAY MORNING BEFORE BURNING OFF. SATURDAY WILL BE A MUCH NICER DAY WITH SUNSHINE...POSSIBLY FILTERED...WITH TEMPERATURES CLOSE TO NORMAL. 08 LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY... FLOW PATTERN ALOFT WILL TRANSITION TO SOUTHWESTERLY FLOW BY EARLY IN THE WEEK. HEIGHT RISES... GOOD LOW LEVEL WARM ADVECTION AND ABUNDANT SUNSHINE SHOULD COMBINE TO BRING ABOUT A NICE BOOST IN TEMPS ON SUNDAY... WITH HIGHS MOSTLY IN THE UPPER 60S TO LOWER 70S ON GUSTY S/SE WINDS. SUN NGT THROUGH MON WILL BRING THE FIRST OF SEVERAL RAIN CHANCES THROUGHOUT THE EXTENDED... AS 30+ KT LOW LEVEL JET AND ATTENDANT MOISTURE TRANSPORT AND CONVERGENCE AIMED OVER THE REGION BY LATE SUN EVE INTO MON AM AHEAD OF AN UPPER LEVEL DISTURBANCE LIFTING OUT OF THE CENTRAL PLAINS. ISOLD/SCTD ELEVATED STORMS SEEM REASONABLE WITH BOTH NAM AND GFS MODELS ADVECTING STEEP PLUME OF MID LEVEL LAPSE RATES IN EXCESS OF 7 C/KM IN 700-500 MB LAYER BY 12Z MON. IN ADDITION... CANT RULE OUT SEEING SOME FOG AND DRIZZLE WITH SUCH STRONG LOW LEVEL MOISTURE TRANSPORT WITH SFC DEWPTS CLIMBING THROUGH THE 50S INTO 60S. ALSO... EXPECTING NON DIURNAL TEMP TREND WITH TEMPS STEADY TO RISING OVRNGT SUN NGT. RAIN CHANCES WILL PERSIST MON NGT INTO TUE WITH SUGGESTIONS OF ADDITIONAL UPPER LEVEL ENERGY LIFTING OUT OF THE PLAINS AHEAD OF WESTERN CONUS TROUGH. OUR REGION WILL CONTINUE TO RESIDE IN SOUTHWESTERLY FLOW ALOFT THROUGH AT LEAST MIDWEEK WITH BROAD... DEEP TROUGH CENTERED OFF THE PACIFIC NORTHWEST COAST. THIS WILL RESULT IN CONTINUATION OF ABOVE TO MUCH ABOVE NORMAL TEMPS WHILE STAYING UNSETTLED... ALTHOUGH SUGGESTION OF LOWER RISK OF PCPN TUE INTO WED WITH MAIN FRONTAL ZONE LOCATED TO OUR NORTH/WEST. ANTICIPATE FLOW PATTERN ALOFT TO FLATTEN OR TRANSITION TO SEMI-ZONAL LATE WEEK AS MORE SUBSTANTIAL ENERGY EJECTS FROM WESTERN TROUGH. THIS WILL SEND THE BOUNDARY BACK THROUGH AS COLD FRONT ACCOMPANIED BY SHOWERS AND STORMS WED NGT THROUGH THU BASED ON THE RECENT MODEL TRENDS OR DPROG/DT OF UKMET... ECMWF AND GFS. MOST AREAS LIKELY TO SEE 0.25 TO 0.75 INCH OF RAIN WITH AREAS OF 1+ INCHES BETWEEN THE TWO MAIN PCPN WINDOWS OF SUN NGT-MON NGT AND WED NGT- THU NGT. MCCLURE && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
432 PM CDT THU OCT 18 2012 .UPDATE... UPDATED FOR 100 PERCENT COVERAGE OF RAINFALL IN THE PERSISTENT BAND OF RAIN OVER THE CWA THE REMAINDER OF THE AFTERNOON. ALSO INCREASED POPS SOMEWHAT OVER THE SOUTH HALF THIS EVENING DUE TO WIDESPREAD COVERAGE. RAINFALL AMOUNTS FROM TODAY AND EARLY EVENING SHOULD RANGE FROM 0.1 TO 0.2 IN MOST LOCATIONS. ERVIN && .PREV DISCUSSION... /ISSUED 352 PM CDT THU OCT 18 2012/ SYNOPSIS... 12Z UA ANALYSIS HAS AN 850MB LOW ALONG THE MN/WI BORDER NORTHEAST OF KMSP. THE 850MB COLD FRONT RAN FROM THE LOW INTO LOWER MICHIGAN AND THEN SOUTH TO SOUTHEAST ARKANSAS AND THEN INTO CENTRAL TEXAS. SEVERAL TROFS RAN BEHIND THE COLD FRONT FROM WI/IL BACK THROUGH IOWA AND NEBRASKA. SATELLITE/RADAR TRENDS THROUGH MID AFTERNOON SHOW EXTENSIVE WRAP AROUND CLOUDS ACROSS THE AREA WITH LIGHT RAIN AND DRIZZLE ACROSS THE AREA. 18Z SFC ANALYSIS PLACES THE SFC LOW NEAR KMSP WITH AN OCCLUDED FRONT NORTHEAST TO ANOTHER SFC LOW OVER WESTERN LAKE SUPERIOR. NUMEROUS WEAK TROFS RAN FROM WI/IL BACK THROUGH IOWA AND INTO NEBRASKA. DEW POINTS WERE MAINLY IN THE 30S AND 40S ACROSS THE MIDWEST. SHORT TERM...TONIGHT AND FRIDAY... ISENTROPIC UPGLIDE WILL CONTINUE ACROSS THE AREA LATE THIS AFTERNOON RESULTING IN A LIGHT RAIN. HOWEVER...DOWNGLIDE WAS OCCURRING ACROSS NORTHERN AND EXTREME NORTHEAST IOWA RESULTING IN DRY CONDITIONS. TRENDS FROM THE RAP INDICATE THIS DOWNGLIDE WILL MOVE INTO THE NORTHWEST TO NORTHERN CWFA EARLY THIS EVENING BRIEFLY ENDING THE RAIN. THE MORE SUBSTANTIAL RAIN WILL PUSH TO THE SOUTHERN THIRD TO 40 PERCENT OF THE CWFA. BY LATE EVENING AND CONTINUING OVERNIGHT WEAK UPGLIDE WILL AGAIN MOVE INTO THE NORTHERN CWFA WHILE THE MORE SUBSTANTIAL RAIN CONTINUES TO SINK SOUTH. THUS LIGHT RAIN/DRIZZLE WILL AGAIN DEVELOP ACROSS THE NORTHERN CWFA. AFTER MIDNIGHT WINDS ACROSS THE NORTHERN PARTS OF THE CWFA DROP OFF SUGGESTING SOME PATCHY FOG MAY DEVELOP PRIOR TO SUNRISE. ON FRIDAY SPOTTY LIGHT RAIN/DRIZZLE WILL CONTINUE EARLY IN THE MORNING WITH SOME PATCHY FOG POSSIBLE ACROSS THE NORTH. ISENTROPIC UPGLIDE AGAIN BECOMES RE-ESTABLISHED BY LATE MORNING AND THROUGH THE AFTERNOON. THUS...LIGHT RAIN IN CENTRAL IOWA WILL AGAIN ADVECT INTO THE WESTERN CWFA AND CONTINUE MOVING EAST THROUGH THE AFTERNOON HOURS. RIGHT NOW MAX TEMPERATURES FOR FRIDAY ARE IN THE UPPER 40S TO LOWER 50S. HOWEVER...THESE MAY STILL BE TOO WARM AND ACTUAL TEMPERATURES COULD BE SIMILAR TO THURSDAY. 08 LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY... UPPER LOW WILL GRADUALLY RELINQUISH CONTROL OF OUR WEATHER FRIDAY NIGHT INTO SATURDAY AS IT CONTINUES TO PUSHLY SLOWLY EAST ACROSS THE GREAT LAKES REGION. AREAS OF LIGHT RAIN AND DRIZZLE LOOK TO SHUT DOWN FRIDAY EVENING WITH SUBSIDENCE BUILDING FOR OVERNIGHT. DESPITE THE SUBSIDENCE HAVE REMAINED MORE ON PESSIMISTIC SIDE ON SKY COVER AND CLEARING TRENDS FRIDAY NIGHT INTO SATURDAY...GIVEN ABUNDANT LOW LEVEL MOISTURE (AIDED BY PAST FEW DAYS OF RAIN) BENEATH INVERSION... LOWER SUN ANGLE... AND EXTENSIVE CLOUD SHIELD AROUND UPPER LOW DEPICTED WELL BY THE NAM MODEL WHICH IS MOST AGGRESSIVE WITH MAINTAINING CLOUDS. AS RESULT... CONTINUE TO BE NEAR WARM SIDE OF GUIDANCE ON LOWS FRIDAY NIGHT AND NEAR BLEND OR COOL SIDE OF GUIDANCE FOR HIGHS ON SATURDAY. PATTERN ALOFT SET TO TRANSITION TO SOUTHWEST FLOW OVER THE REGION BY LATE IN THE WEEKEND... WITH THE MEDIUM RANGE MODELS GENERALLY AGREEING ON MAINTAINING SOUTHWEST FLOW ALOFT THROUGH MUCH OF NEXT WEEK. THIS REGIME FAVORS ABOVE NORMAL TEMPS ALONG WITH BOUTS OF UNSETTLED WEATHER. THE CHALLENGE LIES IN THE DETAILS OF THE FORECAST AS THE MODELS DIVERGE ON ENERGY EJECTING FROM WESTERN TROUGH... ESPECIALLY BY TUESDAY AND CONTINUING INTO THURSDAY... WHICH HAS IMPACT ON MOVEMENT OF FRONTAL ZONE AND SUBSEQUENT TEMPERATURE FORECAST. GIVEN THE UNCERTAINTY... STAYED LARGELY WITH MODEL CONSENSUS ON TEMPS/POPS FOR MONDAY THROUGH THURSDAY. DPROG/DT OF BOTH ECMWF AND GFS SHOW CONTINUED SLOWING AND FURTHER NORTHWEST TREND WITH FRONTAL ZONE IN GENERAL BY TUESDAY INTO THURSDAY. IF TRENDS PERSIST WOULD EXPECT DECREASE IN RAIN CHANCES AND FURTHER WARMING ON TEMPS TO MUCH ABOVE NORMAL FOR SOME OR MOST OF THIS PERIOD TUESDAY INTO THURSDAY. TRANSITION TO MUCH COLDER REGIME IS STILL DEPICTED BY BOTH ECMWF AND GFS BEYOND THE SCOPE OF CURRENT EXTENDED. MAIN CHALLENGE APPEARS TO BE JUST EXACTLY WHEN THIS TRANSITION OCCURS. 05 AVIATION... /ISSUED 1244 PM CDT THU OCT 18 2012/ MVFR CONDITIONS WITH -RA WILL DETERIORATE TO IFR CONDITIONS AFT 00Z/19 AS THE UPPER LOW ROTATES SOUTHEAST INTO NORTHERN ILLINOIS. THE -RA WILL END FOR SEVERAL HOURS BEFORE DZ DVLPS AFT SUNSET. THE POTENTIAL DOES EXIST FOR INCURSIONS OF LIFR PRIOR TO SUNRISE FRIDAY. AFT SUNRISE FRIDAY THERE WILL BE A SLOW IMPROVEMENT TO MVFR CONDITIONS. 08 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
352 PM CDT THU OCT 18 2012 .SYNOPSIS... 12Z UA ANALYSIS HAS AN 850MB LOW ALONG THE MN/WI BORDER NORTHEAST OF KMSP. THE 850MB COLD FRONT RAN FROM THE LOW INTO LOWER MICHIGAN AND THEN SOUTH TO SOUTHEAST ARKANSAS AND THEN INTO CENTRAL TEXAS. SEVERAL TROFS RAN BEHIND THE COLD FRONT FROM WI/IL BACK THROUGH IOWA AND NEBRASKA. SATELLITE/RADAR TRENDS THROUGH MID AFTERNOON SHOW EXTENSIVE WRAP AROUND CLOUDS ACROSS THE AREA WITH LIGHT RAIN AND DRIZZLE ACROSS THE AREA. 18Z SFC ANALYSIS PLACES THE SFC LOW NEAR KMSP WITH AN OCCLUDED FRONT NORTHEAST TO ANOTHER SFC LOW OVER WESTERN LAKE SUPERIOR. NUMEROUS WEAK TROFS RAN FROM WI/IL BACK THROUGH IOWA AND INTO NEBRASKA. DEW POINTS WERE MAINLY IN THE 30S AND 40S ACROSS THE MIDWEST. && .SHORT TERM...TONIGHT AND FRIDAY... ISENTROPIC UPGLIDE WILL CONTINUE ACROSS THE AREA LATE THIS AFTERNOON RESULTING IN A LIGHT RAIN. HOWEVER...DOWNGLIDE WAS OCCURRING ACROSS NORTHERN AND EXTREME NORTHEAST IOWA RESULTING IN DRY CONDITIONS. TRENDS FROM THE RAP INDICATE THIS DOWNGLIDE WILL MOVE INTO THE NORTHWEST TO NORTHERN CWFA EARLY THIS EVENING BRIEFLY ENDING THE RAIN. THE MORE SUBSTANTIAL RAIN WILL PUSH TO THE SOUTHERN THIRD TO 40 PERCENT OF THE CWFA. BY LATE EVENING AND CONTINUING OVERNIGHT WEAK UPGLIDE WILL AGAIN MOVE INTO THE NORTHERN CWFA WHILE THE MORE SUBSTANTIAL RAIN CONTINUES TO SINK SOUTH. THUS LIGHT RAIN/DRIZZLE WILL AGAIN DEVELOP ACROSS THE NORTHERN CWFA. AFTER MIDNIGHT WINDS ACROSS THE NORTHERN PARTS OF THE CWFA DROP OFF SUGGESTING SOME PATCHY FOG MAY DEVELOP PRIOR TO SUNRISE. ON FRIDAY SPOTTY LIGHT RAIN/DRIZZLE WILL CONTINUE EARLY IN THE MORNING WITH SOME PATCHY FOG POSSIBLE ACROSS THE NORTH. ISENTROPIC UPGLIDE AGAIN BECOMES RE-ESTABLISHED BY LATE MORNING AND THROUGH THE AFTERNOON. THUS...LIGHT RAIN IN CENTRAL IOWA WILL AGAIN ADVECT INTO THE WESTERN CWFA AND CONTINUE MOVING EAST THROUGH THE AFTERNOON HOURS. RIGHT NOW MAX TEMPERATURES FOR FRIDAY ARE IN THE UPPER 40S TO LOWER 50S. HOWEVER...THESE MAY STILL BE TOO WARM AND ACTUAL TEMPERATURES COULD BE SIMILAR TO THURSDAY. 08 .LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY... UPPER LOW WILL GRADUALLY RELINQUISH CONTROL OF OUR WEATHER FRIDAY NIGHT INTO SATURDAY AS IT CONTINUES TO PUSHLY SLOWLY EAST ACROSS THE GREAT LAKES REGION. AREAS OF LIGHT RAIN AND DRIZZLE LOOK TO SHUT DOWN FRIDAY EVENING WITH SUBSIDENCE BUILDING FOR OVERNIGHT. DESPITE THE SUBSIDENCE HAVE REMAINED MORE ON PESSIMISTIC SIDE ON SKY COVER AND CLEARING TRENDS FRIDAY NIGHT INTO SATURDAY...GIVEN ABUNDANT LOW LEVEL MOISTURE (AIDED BY PAST FEW DAYS OF RAIN) BENEATH INVERSION... LOWER SUN ANGLE... AND EXTENSIVE CLOUD SHIELD AROUND UPPER LOW DEPICTED WELL BY THE NAM MODEL WHICH IS MOST AGGRESSIVE WITH MAINTAINING CLOUDS. AS RESULT... CONTINUE TO BE NEAR WARM SIDE OF GUIDANCE ON LOWS FRIDAY NIGHT AND NEAR BLEND OR COOL SIDE OF GUIDANCE FOR HIGHS ON SATURDAY. PATTERN ALOFT SET TO TRANSITION TO SOUTHWEST FLOW OVER THE REGION BY LATE IN THE WEEKEND... WITH THE MEDIUM RANGE MODELS GENERALLY AGREEING ON MAINTAINING SOUTHWEST FLOW ALOFT THROUGH MUCH OF NEXT WEEK. THIS REGIME FAVORS ABOVE NORMAL TEMPS ALONG WITH BOUTS OF UNSETTLED WEATHER. THE CHALLENGE LIES IN THE DETAILS OF THE FORECAST AS THE MODELS DIVERGE ON ENERGY EJECTING FROM WESTERN TROUGH... ESPECIALLY BY TUESDAY AND CONTINUING INTO THURSDAY... WHICH HAS IMPACT ON MOVEMENT OF FRONTAL ZONE AND SUBSEQUENT TEMPERATURE FORECAST. GIVEN THE UNCERTAINTY... STAYED LARGELY WITH MODEL CONSENSUS ON TEMPS/POPS FOR MONDAY THROUGH THURSDAY. DPROG/DT OF BOTH ECMWF AND GFS SHOW CONTINUED SLOWING AND FURTHER NORTHWEST TREND WITH FRONTAL ZONE IN GENERAL BY TUESDAY INTO THURSDAY. IF TRENDS PERSIST WOULD EXPECT DECREASE IN RAIN CHANCES AND FURTHER WARMING ON TEMPS TO MUCH ABOVE NORMAL FOR SOME OR MOST OF THIS PERIOD TUESDAY INTO THURSDAY. TRANSITION TO MUCH COLDER REGIME IS STILL DEPICTED BY BOTH ECMWF AND GFS BEYOND THE SCOPE OF CURRENT EXTENDED. MAIN CHALLENGE APPEARS TO BE JUST EXACTLY WHEN THIS TRANSITION OCCURS. 05 && .AVIATION... /ISSUED 1244 PM CDT THU OCT 18 2012/ MVFR CONDITIONS WITH -RA WILL DETERIORATE TO IFR CONDITIONS AFT 00Z/19 AS THE UPPER LOW ROTATES SOUTHEAST INTO NORTHERN ILLINOIS. THE -RA WILL END FOR SEVERAL HOURS BEFORE DZ DVLPS AFT SUNSET. THE POTENTIAL DOES EXIST FOR INCURSIONS OF LIFR PRIOR TO SUNRISE FRIDAY. AFT SUNRISE FRIDAY THERE WILL BE A SLOW IMPROVEMENT TO MVFR CONDITIONS. 08 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ 08/05
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1244 PM CDT THU OCT 18 2012 .UPDATE... TRENDS FROM THE RAP WITH SOME INPUT FROM THE WRF ARE INTERESTING. THE CURRENT PRECIPITATION BAND OVER MUCH OF IOWA IS BEING MAINTAINED BY AN AREA OF BROAD ISENTROPIC LIFT. HOWEVER...THERE IS AN AREA OF ISENTROPIC DOWN GLIDE OCCURRING ACROSS NORTHERN IOWA. THE RAP TRENDS INDICATE THIS DOWN GLIDE WILL BEGIN MOVING INTO THE NORTHWEST CWFA THIS AFTERNOON AND AFFECT NEARLY THE NORTHERN HALF FROM LATE AFTERNOON THROUGH EARLY EVENING. AT THE SAME TIME THE LIFT ACROSS THE SOUTHERN HALF OF THE CWFA WILL BECOME MORE NEUTRAL. WHAT IS BEING SUGGESTED IS THE RAIN ENDING ACROSS THE NORTHERN CWFA DURING THE AFTERNOON OR BECOMING VERY SPOTTY WITH RAIN CONTINUING ACROSS THE SOUTH BUT DECREASING IN AREAL COVERAGE LATE THIS AFTERNOON AND EVENING. BY LATE EVENING AN AREA OF WEAKER ISENTROPIC LIFT BEGINS MOVING INTO THE NORTHERN CWFA SUGGESTING POSSIBLY SOME -RA OR DZ DEVELOPING. THE WRF PARTIALLY COMPLEMENTS WHAT THE RAP IS SUGGESTING. AFTER MIDNIGHT THE WRF SUGGESTS THE RAIN MAY END ACROSS A MAJORITY OF THE AREA WITH DZ DEVELOPING. TEMPERATURES MAY PARTIALLY REBOUND ACROSS THE NORTH WITH THE RAIN ENDING. HOWEVER...MUCH OF THE CWFA WILL REMAIN IN THE 40S FOR THE REMAINDER OF DAYLIGHT HOURS. ACROSS THE FAR EAST/SOUTH TEMPERATURES MAY HOLD IN THE LOW 50S. ..08.. && .AVIATION... MVFR CONDITIONS WITH -RA WILL DETERIORATE TO IFR CONDITIONS AFT 00Z/19 AS THE UPPER LOW ROTATES SOUTHEAST INTO NORTHERN ILLINOIS. THE -RA WILL END FOR SEVERAL HOURS BEFORE DZ DVLPS AFT SUNSET. THE POTENTIAL DOES EXIST FOR INCURSIONS OF LIFR PRIOR TO SUNRISE FRIDAY. AFT SUNRISE FRIDAY THERE WILL BE A SLOW IMPROVEMENT TO MVFR CONDITIONS. ..08.. && .PREV DISCUSSION... /ISSUED 1012 AM CDT THU OCT 18 2012/ UPDATE... RADAR TRENDS THROUGH MID MORNING SHOWS THE PRECIP IS MOVING IN SOONER THAN EXPECTED. EXTRAPOLATION PLACES -RA OR SHRA ACROSS NEARLY ALL THE AREA BY MID DAY. DURING THE AFTERNOON HOURS THE CURRENT BAND OF RAIN ACROSS CENTRAL IOWA WILL ROTATE ACROSS AREAS SOUTH OF HWY 20. THE IMMEDIATE HWY 20 CORRIDOR SHOULD SEE MORE SHOWERS THAN CONTINUOUS LIGHT RAIN. BY LATE AFTERNOON MORE SHOWERS ARE EXPECTED ALONG/NORTH OF HWY 30 WITH THE MORE PERSISTENT LIGHT RAIN CONTINUES FROM THE I-80 CORRIDOR ON SOUTH. TEMPERATURES WILL BARELY MOVE FOR THE REMAINDER OF THE DAY WHERE THE RAIN PERSISTS. THE EXCEPTION WILL BE THE FAR EAST/SOUTH WHERE TEMPERATURES MAY MANAGE TO RISE INTO THE LOWER 50S BEFORE THE RAIN BEGINS. ..08.. PREV DISCUSSION... /ISSUED 330 AM CDT THU OCT 18 2012/ SYNOPSIS... THERE IS A STRONG SURFACE LOW OVER NORTHWEST MINNESOTA...ALONG WITH A SECONDARY SURFACE LOW OVER NORTHEAST WISCONSIN. THE STRONG COLD FRONT THAT SWEPT THROUGH THE FORECAST AREA WEDNESDAY AFTERNOON IS NOW WELL EAST OF THE AREA...HAVING PUSHED INTO INDIANA AND MICHIGAN OVERNIGHT. WE ARE LEFT WITH DEEP COLD AIR ADVECTION OVER THE AREA WITH WEST TO SOUTHWEST WINDS IN THE 10-15KT RANGE. AN AREA OF CONVERGENCE AT MID LEVELS AND A SHORTWAVE IN THE STRONG...CUT OFF UPPER LEVEL LOW OVER SOUTHERN MINNESOTA HAS GENERATED AN AREA OF SHOWERS OVER SOUTHERN MINNESOTA THIS MORNING...WITH OTHER SURROUNDING SITES REPORTING DRIZZLE. LE SHORT TERM...TODAY AND TONIGHT THE STRONG CUT OFF UPPER LEVEL LOW NOW OVER SOUTHERN MINNESOTA IS NOW FORECAST TO SLOWLY EAST SOUTHEAST TODAY AND TONIGHT...ENDING UP OVER NORTHERN ILLINOIS BY FRIDAY MORNING. THE SURFACE LOW IS EXPECTED TO TAKE A SIMILAR TRACK AS THE SYSTEM BECOMES MORE STACKED WITH TIME. THIS IS GOING TO KEEP THE FORECAST AREA IN A VERY MOIST ATMOSPHERE WITHIN WHICH IT WILL BE VERY EASY FOR WEAK SHORTWAVES TO PRODUCE RAIN. THUS...WE ARE GOING TO GET SOME MORE MUCH NEEDED RAINFALL TODAY...THOUGH QPF AMOUNTS WILL BE RELATIVELY LIGHT. FOR NOW...AM TRACKING A DECENT WAVE OF CONVERGENCE AND 500MB PVA THAT ALONG WITH SOME WRAP-AROUND ISENTROPIC LIFT WILL BRING A BAND OF RAIN INTO THE FORECAST AREA DURING THE LATE MORNING AND EARLY AFTERNOON HOURS. IT WILL BE DIURNALLY ENHANCED...SO IT WILL LIKELY MUCH LARGER THAN WHAT WE ARE NOW SEEING CROSSING INTO NORTHWEST IOWA. THAT SAID...HAVE SOME LIKELY TO CATEGORICAL POPS ACROSS THE FORECAST AREA FOR THIS AFTERNOON AND EVENING AS THIS PARTICULAR WAVE OF PRECIPITATION MOVES ACROSS THE AREA. UNDER ALL THE CLOUDS THIS IS GOING TO GENERATE TODAY...HIGH TEMPERATURES ARE GOING TO BE TRAPPED IN THE MID 40S TO LOW 50S. THIS WILL ACT TO KEEP TEMPERATURES UP TONIGHT AS WELL. WHILE THE MAIN SHORTWAVE AND PRECIPITATION WILL SHIFT OFF TO THE SOUTHEAST OVERNIGHT...EXPECT THAT WE WILL STILL BE UNDER A LOT OF CLOUD COVER MOST OF THE NIGHT. DRIZZLE MAY BE FAIRLY PREVALENT TONIGHT...BUT FOR NOW HAVE LEFT OUT OF THE PUBLIC FORECAST AND WE CAN RE-EVALUATE WITH LATER FORECASTS. MIN TEMPS TONIGHT...WHILE COLDER THAN THIS MORNINGS VALUES WILL BE DOWN IN THE AROUND 40 TO 45 RANGE. LE LONG TERM...FRIDAY THROUGH WEDNESDAY A FINAL WAVE OF VORTICITY ROTATING AROUND THE DEPARTING UPPER LOW WILL PASS THROUGH THE AREA DURING THE DAY FRIDAY...KEEPING AT LEAST SCATTERED LIGHT SHOWERS GOING...ALONG WITH CONTINUED CLOUDY AND COOL CONDITIONS. WITH GOOD MODEL AGREEMENT...HAVE INCREASED POPS TO LIKELY OVER ALL BUT THE FAR SOUTHWEST...FOLLOWING THE TIMING OF THE UPPER LEVEL IMPULSE. TEMPERATURES WILL STRUGGLE INTO THE UPPER 40S NORTH TO LOWER 50S SOUTH. QPF VALUES ARE KEPT BELOW A TENTH OF AN INCH BASED ON THE WEAK LIFT AND SOMEWHAT LIMITED MOISTURE WRAPPING AROUND THE LARGE UPPER LOW. FRIDAY NIGHT...HOW LONG THE CYCLONIC FLOW LINGERS OVER THE AREA...ALONG WITH THE AMOUNT LOW LEVEL MOISTURE WILL BE CRITICAL TO CLOUD COVER AND OVERNIGHT MINS. WILL STAY THE COURSE WITH THE SLIGHTLY SLOWER AND CONSISTENT ECMWF THAT WOULD KEEP AT LEAST MOSTLY CLOUDY SKIES IN PLACE...HOLDING MINS IN THE UPPER 30S TO LOWER 40S. THERE IS SOME INDICATION THAT THERE COULD BE POCKETS OF CLEARING ROTATING THROUGH...WHICH COULD RESULT IN MUCH COOLER TEMPERATURES AS LOW AS THE MID 30S...ESPECIALLY ACROSS THE NORTH AND NORTHEAST... THAT WILL NEED TO BE WATCHED FOR LATER FORECASTS. OVER THE WEEKEND...A TRANSITORY SURFACE RIDGE WILL BE FOLLOWED BY A SHARP WARMING TREND COMMENCING SATURDAY NIGHT THAT SHOULD PUSH HIGH TEMPERATURES FROM THE 50S SATURDAY...INTO THE 70S SUNDAY. DEVELOPING SOUTHERLY WINDS SHOULD LIMIT MINS SATURDAY NIGHT TO THE 50S. A DEVELOPING SW FLOW IS SHOWN SURGING GULF MOISTURE AND STRONG WARM ADVECTION ALOFT INTO THE AREA BY SUNDAY EVENING. A PERSISTENT SW FLOW OF GULF MOISTURE IS THEN DEPICTED IMPINGING ON A DEVELOPING SURFACE BOUNDARY THAT STALLS OUT OVER THE REGION IN A SW TO NE CONFIGURATION MONDAY THROUGH WEDNESDAY. THE ECMWF AND GFS WOULD KEEP OUR AREA FIRMLY IN THE WARM SECTOR FOR MONDAY...WHILE THE GEM AND DGEX HAVE THE BOUNDARY SETTING UP OVERHEAD OR EVEN SOUTH OF THE AREA. IF THE FORMER IS CORRECT...TEMPERATURES COULD BE WELL INTO THE 70S TO POSSIBLY NEAR 80...WHILE THE LATTER SOLUTIONS COULD RESULT IN WIDESPREAD CLOUD COVER...PRECIPITATION...AND TEMPERATURES ONLY IN THE 50S. LATEST MODEL SOLUTIONS CONTINUE TO DIVERGE TUE INTO WED IN THE CRITICAL LOCATION OF THIS SURFACE FRONT. OUR BLENDED APPROACH RESULTS IN A MIDDLE OF THE ROAD FORECAST OF SEVERAL DAYS OF AT LEAST CHANCE POPS FOR SHOWERS AND POSSIBLE THUNDERSTORMS WITH HIGHS IN 60S AND 70S AND LOWS IN THE 50S. WITH THE GFS SHOWING PW VALUES OVER 200 PERCENT OVER THE REGION...THERE WILL BE A POTENTIAL FOR ANOTHER ROUND OF SOAKING RAINS SOMEWHERE IN THE AREA. SHEETS && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1129 PM CDT WED OCT 17 2012 .AVIATION... A LARGE UPPER LOW PRESSURE SYSTEM WILL MOVE SHOWERS AND CIGS BACK INTO THE REGION DURING THE DAY THURSDAY. UNTIL THEN...WEST WINDS OF 12 TO 25 KTS WILL GUST THROUGH THE NIGHT...WITH OTHERWISE VFR AND DRY CONDITIONS. ANY CIGS WILL BE 4500 FT OR HIGHER. SHOWERS WILL SLIDE SOUTHEAST OVER THE REGION BY 15 TO 18Z...LASTING THROUGH THURSDAY NIGHT. INITIALLY...THESE SHOULD BE VFR SHOWERS...BUT BY LATE AFTERNOON AND EVENING...FREQUENT MVFR TO POSSIBLE IFR CONDITIONS ARE NOW LIKELY...AT ALL SITES IN EASTERN IOWA AND NORTHWEST ILLINOIS. WINDS WILL REMAIN AT OVERNIGHT LEVELS THROUGH THE DAY THURSDAY. THE CONDITIONS LATE THURSDAY AFTERNOON AND EVENING SHOULD GENERALLY RANGE FROM 800 FT TO 1500 FT CIGS AND VISIBILITIES OF 4 TO 6 MILES IN LIGHT TO BRIEF MODERATE RAIN SHOWERS. ERVIN && .PREV DISCUSSION... /ISSUED 647 PM CDT WED OCT 17 2012/ UPDATE... UPDATED POPS AND WEATHER TO REFLECT THE CURRENT RADAR POSITION OF WIDESPREAD SHOWERS FOR THIS AFTERNOON AND EARLY EVENING. ERVIN SYNOPSIS... 12Z UA ANALYSIS HAS 850MB LOWS ON THE NORTH SHORE OF LAKE WINNIPEG AND IN NORTHWEST MINNESOTA. AN 850MB COLD FRONT RAN FROM THE MINNESOTA LOW INTO SOUTHEAST NEW MEXICO WITH A TROF FROM SOUTHERN MINNESOTA INTO SOUTH TEXAS. SATELLITE/RADAR TRENDS SHOWS EXTENSIVE LOW AND MID LEVEL CLOUDS WITH STRONG CONVECTION ACROSS MISSOURI AND MORE SCATTERED CONVECTION ACROSS IOWA/ILLINOIS. 18Z SFC ANALYSIS HAS A LOW EAST OF KFAR WITH THE COLD FRONT SOUTH INTO SOUTHEAST KANSAS. TWO MESO LOWS WERE IN SOUTHWEST MISSOURI AND NORTHEAST OKLAHOMA. A PRE-FRONTAL TROF RAN FROM JUST EAST OF KMSP TO ABOUT KIRK. DEW POINTS AHEAD OF THE COLD FRONT WERE IN THE 50S AND 60S WITH 20S AND 30S BEHIND THE COLD FRONT IN THE PLAINS. SHORT TERM...TONIGHT AND THURSDAY THE CURRENT PICTURE AT MID AFTERNOON HAS MID LEVEL FORCING OR A WEAK VORT MAX PUSHING A SLUG OF MAINLY SHRA ACROSS THE CWFA. A MUCH STRONGER VORT MAX IS ROTATING NORTHEAST ACROSS MISSOURI. IF THE TRENDS OF THE RAP ARE CORRECT...THERE SHOULD BE A BAND OF ENHANCED CONVECTION THAT DEVELOPS LATE THIS AFTERNOON IN THE SOUTHEAST QUADRANT OF THE CWFA AND ROTATES NORTHEAST. THIS BAND OF CONVECTION WILL BE ACROSS ROUGHLY THE EASTERN 40 PERCENT OF THE CWFA DURING THE EARLY EVENING HOURS BEFORE EXITING THE CWFA. SOME LINGERING SHRA SHOULD THEN BE SEEN IN THE THE MID AND LATE EVENING HOURS BEFORE ENDING. AFTER MIDNIGHT THERE SHOULD BE SOME CLEARING OF THE CLOUDS WITH DRY CONDITIONS AS CONDENSATION PRESSURE DEFICITS RISE CONSIDERABLY. CONDENSATION PRESSURE DEFICITS IN THE 850-700MB LAYER COLLAPSE AGAIN ACROSS THE CWFA PRIOR TO SUNRISE BUT THE 1000-850MB LAYER CONDENSATION PRESSURE DEFICITS ONLY LOWER SLIGHTLY. THUS MOST OF THE AREA SHOULD REMAIN DRY AFTER MIDNIGHT BUT SOME SPRINKLES MIGHT ENTER THE FAR NORTHWEST PART OF THE CWFA JUST PRIOR TO DAWN. THURSDAY...WRAP AROUND CLOUDS/PRECIP MOVE SOUTHEAST THROUGH THE CWFA DURING THE MORNING HOURS. STEEP LAPSE RATES WILL AID IN DEVELOPING NEW DIURNAL CLOUDS IN AREAS THAT WERE PARTIALLY CLEAR AT SUNRISE. SCATTERED SHRA WILL BECOME MORE NUMEROUS DURING THE DAY AS A VORT MAX ROTATES THROUGH AND INCREASES THE LIFT. THE FREEZING LEVEL IS 3.0-3.5 KFT AGL PLUS/MINUS 700 FT DEPENDING ON LOCAL ELEVATION ABOVE SEA LEVEL. HOWEVER...THE LOWEST 2 KFT ABOVE THE GROUND REMAINS ABOVE FREEZING. THUS IN THE STRONGER SHOWERS THE POTENTIAL DOES EXIST FOR SOME SMALL GRAUPEL TO DEVELOP THAT REACHES THE GROUND. TEMPERATURES WILL REMAIN IN THE 40S FOR MUCH OF THE DAY BUT THE SOUTHEAST THIRD TO 40 PERCENT OF THE CWFA MAY MANAGE TO GET INTO THE LOWER 50S. REGARDLESS...IT WILL BE A COLD RAW DAY WHEN THE WIND IS FACTORED IN. 08 LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY UPPER LOW PROGGED TO EXIT INTO THE GREAT LAKES REGION BY FRI NGT. UNTIL THEN WILL SEE CONSIDERABLE CLOUDINESS ALONG WITH BOUTS OF LIGHT RAIN OR SHOWERS... AS SPOKES OF ENERGY ROTATE DOWN THE BACKSIDE OF THE LOW. CLOUDS WILL ACT AS BLANKET AND LIMIT DIURNAL SWINGS INTO FRI. CLOUD FORECAST CHALLENGING FRI NGT INTO SAT WITH OVERALL INCOMING SUBSIDENCE IN WAKE OF DEPARTING LOW SUPPORTIVE OF CLEARING... BUT NAM BUFR SOUNDINGS DEPICT A LOT OF LOW LEVEL MOISTURE TRAPPED BENEATH SUBSIDENCE INVERSION. TIME OF YEAR WITH LOWER SUN ANGLE BECOMING MORE FAVORABLE FOR THESE SCENARIOS AND NUDGED TOWARD A MORE PESSIMISTIC SKY COVER FRI NGT THUS STAYING AT OR ABOVE WARM SIDE OF GUIDANCE ON LOWS. SAT-SUN... DRY WITH WARMING TREND TO ABOVE NORMAL TEMPS BY SUN AS NEXT SIGNIFICANT TROUGH PUSHES INTO THE PACIFIC NORTHWEST... WHICH RESULTS IN DOWNSTREAM AMPLIFICATION OF UPPER RIDGE OVER THE REGION. MON-WED... ABOVE NORMAL TEMPS GENERALLY SUGGESTED WITH DEEP TROUGHING OVER THE WESTERN CONUS AND SW FLOW ALOFT. SW FLOW COUPLED WITH FRONTAL ZONE WAVERING NEARBY WILL RESULT IN OCCASIONAL RAIN CHCS AS WELL DURING THE PERIOD. THE FIRST RAIN CHCS APPEAR TO ARRIVE AS EARLY AS MONDAY MORNING WITH MORE ROBUST LOW LEVEL WARM ADVECTION REGIME. OTHERWISE... IT IS DIFFICULT TO PIN DOWN RAIN CHCS THEREAFTER WITH MODELS OFFERING DIFFERENCES ON LOCATION OF THE FRONT AND TIMING OF UPPER LEVEL DISTURBANCES EJECTING FROM WESTERN TROUGH. TRANSITION TO SIGNIFICANTLY COLDER REGIME IS DEPICTED BY ECMWF AND GFS BY THE END OF NEXT WEEK INTO NEXT WEEKEND. 05 AVIATION... /ISSUED 1247 PM CDT WED OCT 17 2012/ A COLD FRONT WILL SWEEP THROUGH EASTERN IOWA AND ILLINOIS IN THE 18Z/17 TO 00Z/18 TIME FRAME. VFR WX IS GENERALLY EXPECTED WITH SPRINKLES OR SHRA. ALONG/EAST OF THE MISSISSIPPI RIVER ISOLD TSRA WILL BE POSSIBLE THAT ARE EXPECTED TO BECOME MORE NUMEROUS AFT 21Z. VFR CONDITIONS ARE EXPECTED BUT THERE MAY BE BRIEF INCURSIONS OF MVFR CONDITIONS WITH ANY TSRA OR STRONGER SHRA. AFT 00Z/18 VFR CONDITIONS ARE EXPECTED. CIGS WILL LOWER AGAIN AFT 12Z/18 BUT SHOULD REMAIN VFR. 08 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS GRAY ME
941 PM EDT FRI OCT 19 2012 .SYNOPSIS... LOW PRESSURE WILL MOVE VERY SLOWLY EAST FROM THE GREAT LAKES THROUGH SATURDAY. A COLD FRONT EXTENDING TO THE SOUTH AND EAST OF THIS LOW WILL PUSH TOWARD NEW ENGLAND SATURDAY. EXPECT CLOUDS AND SCATTERED SHOWERS WITH AN UPPER LOW SATURDAY NIGHT INTO MONDAY. HIGH PRESSURE WILL BUILD BY TO OUR SOUTH ON TUESDAY. A WARM FRONT WILL BRING CLOUDS AND A CHANCE OF PRECIPITATION TO THE AREA TUESDAY NIGHT INTO THURSDAY. A COLD FRONT WILL APPROACH THE REGION LATE FRIDAY. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 930 PM UPDATE... UPDATED POP AND QPF BASED ON RADAR AND OBSERVATIONS. ALSO UPDATED TEMPERATURES BASED ON CURRENT TRENDS AND OBSERVATIONS. ADDED THUNDERSTORMS INTO WESTERN MAINE AND NORTHWESTERN MAINE AS A FEW ISOLATED CELLS CONTINUE TO POP UP OUT AHEAD OF THE LEADING EDGE OF THE DRY SLOT. 800 PM UPDATE... ADDED THUNDERSTORMS TO THE FORECAST FOR EASTERN NEW HAMPSHIRE AND FAR WESTERN MAINE DUE TO SOME CONVECTION THAT HAS KICKED OFF ON THE LEADING EDGE OF THE DRY SLOT. 600 PM UPDATE... MADE SOME MINOR ADJUSTMENTS TO THE POPS AND SLIGHTLY LOWERED QPF NORTH OF THE MOUNTAINS DUE TO SHADOW EFFECTS. UPDATED TEMPERATURES BASED ON CURRENT OBSERVATIONS AND TRENDS. PREVIOUS DISCUSSION... PCPN HAS BEEN HAVING A DIFFICULT TIME MAKING ITS PROGRESSION TO THE E TODAY. HAVE BACKED OFF ON POPS FOR THE REST OF THE AFTN...THEN QUICKLY INCREASE THE POPS THEREAFTER. LATEST HRRR RUN HAS THE BULK OF THE PCPN ENTERING MAINE AFT 21Z. PERIODS OF RAIN WILL CONTINUE TONIGHT. PREFER THE GFS SOLN TODAY AS HIGHEST QPF WILL BE ALIGNED ALONG THE MTNS IN E-CNTRL NH AND FOOTHILLS IN MAINE. SOUTHEAST GRADIENT...HIGH PRECIPITABLE WATERS AND AN INCREASING DEW POINTS JUST TO OUR SOUTH WILL ALLOW THE RAIN TO BECOME HEAVY AT TIMES STARTING THIS EVENING. LARGE UPPER LEVEL VORTEX WILL CONT TO SLOWLY MARCH EAST OVERNIGHT. EXPECT AREAS OF FOG TO REDEVELOP WITH PATCHY DRIZZLE. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... AFTER PERIODS OF RAIN VERY EARLY ON SATURDAY...MAINLY OVER EASTERN SECTIONS...A DRY SLOW WILL ROTATE INTO THE REGION. IN FACT...A BLEND OF MAV/MET MOS YIELDS TEMPS INT EH LOWER 70S OVER SOUTHERN NH. COOLER READINGS WILL OCCUR OVER EASTERN SECTIONS WHICH WILL HAVE THE MOST LOW CLOUD COVER AND WINDS OFF THE CHILLY GULF OF MAINE. BY SATURDAY NIGHT...THE UPPER LOW WILL APPROACH NORTHERN SECTIONS. EXPECT SCT SHOWERS IN THE MTNS. WINDS WILL SWITCH TO THE SW BY LATE AT NIGHT. && .LONG TERM /SUNDAY THROUGH FRIDAY/... AN UPPER TROF MOVES THRU NEW ENGLAND SUNDAY WITH AN ASSOCIATED COLD FRONT MAY BRING SOME SCT SHWRS TO THE MTNS WITH DRY CONDS ELSEWHERE OVER SRN/ERN AREAS DUE TO THE DOWN SLOPING WNWLY WINDS. A DRY WEATHER PATTERN DEVELOPS DURING THE WEEK AS A DRY WNWLY FLOW DEVELOPS THRU THE AS AN UPPER RIDGE BUILDS TO THE WEST OF NEW ENGL. TEMPS WILL BEGIN THE WEEK COOL BUT A WARMING TREND IS EXPECTED OVER THE MIDDLE TO LATTER PART OF THE WEEK. GENERALLY USED A BLEND OF THE ADJUSTED GMOS TEMPS. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...IFR/LIFR CONDS CONTS TO DEVELOP LATE THIS AFTN AND CONTINUES THRU TNGT...THEN IMPROVES AS THE COLD FNT MOVES THRU ON SATURDAY. LLWS ADDED TO TAFS FOR INTO TNGT AS STRONG S SE LOW LVL JET UP TO 50 KT DEVELOPS AT 2000 FT. THE KHIE MTR IS NOW BACK. LONG TERM... MAINLY VFR. && .MARINE... SHORT TERM...WILL UPDATE TO INPUT LATEST OBSERVED DATA WHICH WILL RESULT IN LITTLE IF ANY CHANGES TO THE PREVIOUS FCST. WILL CONT THE GLW FOR THE OPEN WATERS AND THE SCA FOR THE BAYS. MODELS BRING A STRONG LOW LVL JET UP TO 50 KT AT 2000 FT ACROSS THE WATERS DURING THIS TIME FRAME AND EXPECT GUSTS OF 35 KT TO BRIEFLY MIX DOWN. WINDS DROP OFF SATURDAY AS THE GRADIENT DECREASES QUICKLY AS THE CD FNT SLOWLY MOVES THRU. SEAS WILL BE SLOW TO SUBSIDE SO THE GLW WILL LIKELY BE REPLACED WITH AN SCA FOR SATURDAY. LONG TERM... SUNDAY THRU MONDAY PSBL SCA WNWLY WINDS. && .HYDROLOGY... USED RFC/HPC QPF WHICH ARE IN VERY GOOD AGREEMENT. THE NAM QPF APPEARS WAY OVERDONE WITH 3 INCH MAX WHILE GFS AND 12Z ECMWF SHOW MAX OF 1 TO 1.5 INCH OVER SRN ZONES WHICH APPEARS MORE LIKELY. THE RFC/HPC QPF STORM TOTAL IS A GOOD COMPROMISE WITH MAX AMOUNTS OVER 1.5 INCHES BUT LESS THAN 2 INCHES AND FALL FROM E-CNTRL NH TO THE WRN FOOTHILLS OF ME. THIS MUCH QPF IS WELL BELOW FLASH FLOOD GUIDANCE AND PRELIMINARY RFC RIVER FCST KEEPING ALL POINT FCST BELOW FLOOD STAGE THOUGH IT DOES SHOW SOME SHARP RISES OVER CENTRAL NH. && .TIDES/COASTAL FLOODING... HIGH ASTRONOMICAL TIDES WILL CONT THROUGH SATURDAY. WITH INCREASING ONSHORE FLOW TNGT ALONG WITH MODESTLY BUILDING SEAS THERE WILL BE STORM SURGE ON TOP OF THE HIGH TIDE WHICH COULD PUSH THE TIDE CLOSE TO...BUT KEEP IT BELOW FLOOD STAGE. STILL THE WAVE ACTION COULD LEAD TO SOME MODEST SPLASH OVER AND BEACH EROSION PROBLEMS...TONIGHT AND SATURDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EDT SATURDAY FOR ANZ151-153. GALE WARNING UNTIL 7 AM EDT SATURDAY FOR ANZ150-152-154. && $$ SYNOPSIS... NEAR TERM...KISTNER SHORT TERM... LONG TERM... AVIATION... MARINE... HYDROLOGY... TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS GRAY ME
757 PM EDT FRI OCT 19 2012 .SYNOPSIS... LOW PRESSURE WILL MOVE VERY SLOWLY EAST FROM THE GREAT LAKES THROUGH SATURDAY. A COLD FRONT EXTENDING TO THE SOUTH AND EAST OF THIS LOW WILL PUSH TOWARD NEW ENGLAND SATURDAY. EXPECT CLOUDS AND SCATTERED SHOWERS WITH AN UPPER LOW SATURDAY NIGHT INTO MONDAY. HIGH PRESSURE WILL BUILD BY TO OUR SOUTH ON TUESDAY. A WARM FRONT WILL BRING CLOUDS AND A CHANCE OF PRECIPITATION TO THE AREA TUESDAY NIGHT INTO THURSDAY. A COLD FRONT WILL APPROACH THE REGION LATE FRIDAY. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 800 PM UPDATE... ADDED THUNDERSTORMS TO THE FORECAST FOR EASTERN NEW HAMPSHIRE AND FAR WESTERN MAINE DUE TO SOME CONVECTION THAT HAS KICKED OFF ON THE LEADING EDGE OF THE DRY SLOT. 600 PM UPDATE... MADE SOME MINOR ADJUSTMENTS TO THE POPS AND SLIGHTLY LOWERED QPF NORTH OF THE MOUNTAINS DUE TO SHADOW EFFECTS. UPDATED TEMPERATURES BASED ON CURRENT OBSERVATIONS AND TRENDS. PREVIOUS DISCUSSION... PCPN HAS BEEN HAVING A DIFFICULT TIME MAKING ITS PROGRESSION TO THE E TODAY. HAVE BACKED OFF ON POPS FOR THE REST OF THE AFTN...THEN QUICKLY INCREASE THE POPS THEREAFTER. LATEST HRRR RUN HAS THE BULK OF THE PCPN ENTERING MAINE AFT 21Z. PERIODS OF RAIN WILL CONTINUE TONIGHT. PREFER THE GFS SOLN TODAY AS HIGHEST QPF WILL BE ALIGNED ALONG THE MTNS IN E-CNTRL NH AND FOOTHILLS IN MAINE. SOUTHEAST GRADIENT...HIGH PRECIPITABLE WATERS AND AN INCREASING DEW POINTS JUST TO OUR SOUTH WILL ALLOW THE RAIN TO BECOME HEAVY AT TIMES STARTING THIS EVENING. LARGE UPPER LEVEL VORTEX WILL CONT TO SLOWLY MARCH EAST OVERNIGHT. EXPECT AREAS OF FOG TO REDEVELOP WITH PATCHY DRIZZLE. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... AFTER PERIODS OF RAIN VERY EARLY ON SATURDAY...MAINLY OVER EASTERN SECTIONS...A DRY SLOW WILL ROTATE INTO THE REGION. IN FACT...A BLEND OF MAV/MET MOS YIELDS TEMPS INT EH LOWER 70S OVER SOUTHERN NH. COOLER READINGS WILL OCCUR OVER EASTERN SECTIONS WHICH WILL HAVE THE MOST LOW CLOUD COVER AND WINDS OFF THE CHILLY GULF OF MAINE. BY SATURDAY NIGHT...THE UPPER LOW WILL APPROACH NORTHERN SECTIONS. EXPECT SCT SHOWERS IN THE MTNS. WINDS WILL SWITCH TO THE SW BY LATE AT NIGHT. && .LONG TERM /SUNDAY THROUGH FRIDAY/... AN UPPER TROF MOVES THRU NEW ENGLAND SUNDAY WITH AN ASSOCIATED COLD FRONT MAY BRING SOME SCT SHWRS TO THE MTNS WITH DRY CONDS ELSEWHERE OVER SRN/ERN AREAS DUE TO THE DOWN SLOPING WNWLY WINDS. A DRY WEATHER PATTERN DEVELOPS DURING THE WEEK AS A DRY WNWLY FLOW DEVELOPS THRU THE AS AN UPPER RIDGE BUILDS TO THE WEST OF NEW ENGL. TEMPS WILL BEGIN THE WEEK COOL BUT A WARMING TREND IS EXPECTED OVER THE MIDDLE TO LATTER PART OF THE WEEK. GENERALLY USED A BLEND OF THE ADJUSTED GMOS TEMPS. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...IFR/LIFR CONDS CONTS TO DEVELOP LATE THIS AFTN AND CONTINUES THRU TNGT...THEN IMPROVES AS THE COLD FNT MOVES THRU ON SATURDAY. LLWS ADDED TO TAFS FOR INTO TNGT AS STRONG S SE LOW LVL JET UP TO 50 KT DEVELOPS AT 2000 FT. THE KHIE MTR IS NOW BACK. LONG TERM... MAINLY VFR. && .MARINE... SHORT TERM...WILL UPDATE TO INPUT LATEST OBSERVED DATA WHICH WILL RESULT IN LITTLE IF ANY CHANGES TO THE PREVIOUS FCST. WILL CONT THE GLW FOR THE OPEN WATERS AND THE SCA FOR THE BAYS. MODELS BRING A STRONG LOW LVL JET UP TO 50 KT AT 2000 FT ACROSS THE WATERS DURING THIS TIME FRAME AND EXPECT GUSTS OF 35 KT TO BRIEFLY MIX DOWN. WINDS DROP OFF SATURDAY AS THE GRADIENT DECREASES QUICKLY AS THE CD FNT SLOWLY MOVES THRU. SEAS WILL BE SLOW TO SUBSIDE SO THE GLW WILL LIKELY BE REPLACED WITH AN SCA FOR SATURDAY. LONG TERM... SUNDAY THRU MONDAY PSBL SCA WNWLY WINDS. && .HYDROLOGY... USED RFC/HPC QPF WHICH ARE IN VERY GOOD AGREEMENT. THE NAM QPF APPEARS WAY OVERDONE WITH 3 INCH MAX WHILE GFS AND 12Z ECMWF SHOW MAX OF 1 TO 1.5 INCH OVER SRN ZONES WHICH APPEARS MORE LIKELY. THE RFC/HPC QPF STORM TOTAL IS A GOOD COMPROMISE WITH MAX AMOUNTS OVER 1.5 INCHES BUT LESS THAN 2 INCHES AND FALL FROM E-CNTRL NH TO THE WRN FOOTHILLS OF ME. THIS MUCH QPF IS WELL BELOW FLASH FLOOD GUIDANCE AND PRELIMINARY RFC RIVER FCST KEEPING ALL POINT FCST BELOW FLOOD STAGE THOUGH IT DOES SHOW SOME SHARP RISES OVER CENTRAL NH. && .TIDES/COASTAL FLOODING... HIGH ASTRONOMICAL TIDES WILL CONT THROUGH SATURDAY. WITH INCREASING ONSHORE FLOW TNGT ALONG WITH MODESTLY BUILDING SEAS THERE WILL BE STORM SURGE ON TOP OF THE HIGH TIDE WHICH COULD PUSH THE TIDE CLOSE TO...BUT KEEP IT BELOW FLOOD STAGE. STILL THE WAVE ACTION COULD LEAD TO SOME MODEST SPLASH OVER AND BEACH EROSION PROBLEMS...TONIGHT AND SATURDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EDT SATURDAY FOR ANZ151-153. GALE WARNING UNTIL 7 AM EDT SATURDAY FOR ANZ150-152-154. && $$ SYNOPSIS... NEAR TERM...KISTNER SHORT TERM... LONG TERM... AVIATION... MARINE... HYDROLOGY... TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
138 AM EDT THU OCT 18 2012 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 432 PM EDT WED OCT 17 2012 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A TROF IN THE PROCESS OF AMPLIFYING OVER THE PLAINS. THERE ARE A NUMBER OF EMBEDDED SHORTWAVES IN THE DEEPENING TROF...BUT THE 130-140KT JET PER LATEST RUC CURRENTLY DROPPING DOWN THE BACKSIDE OF THE TROF WILL BE THE FACTOR LEADING TO THE TROF CONTINUING TO DEEPEN. IN FACT...TROF WILL BECOME DEEP FOR THIS TIME OF YEAR. AT PEAK INTENSITY THU OVER THE MID/UPPER MISSISSIPPI VALLEY...500MB HEIGHTS WILL BE 3.5 STANDARD DEVIATIONS BLO THE LONG TERM AVG FOR MID OCT. AT THE SFC...LOW PRES OF 29.1 INCHES IS OVER NW MN WITH COLD FRONT EXTENDING INTO FAR WRN WI/FAR ERN IA AND MO. SO FAR...PCPN COVERAGE HAS BEEN GREATEST NEAR THE SFC LOW OVER NW MN/ERN ND. HOWEVER...SHRA ARE INCREASING IN COVERAGE SOUTHWARD ALONG/AHEAD OF COLD FRONT AS UPPER DIFFLUENCE IMPROVES DUE TO AFOREMENTIONED UPPER JET DROPPING DOWN BACKSIDE OF THE TROF. AS TROF CONTINUES TO DEEPEN TONIGHT...A NEW LOW PRES CENTER IS EXPECTED TO DEVELOP ON COLD FRONT IN ERN WI AND THEN LIFT NW TO THE VCNTY OF WRN LAKE SUPERIOR THU MORNING. DEEPENING SYSTEM WILL LEAD TO LOW-LEVEL JET RAMPING UP TO AROUND 50KT WHICH WILL TRANSPORT ABUNDANT MOISTURE N INTO THE AREA (PRECIPITABLE WATER INCREASES TO 200PCT OF NORMAL OR BETTER). STRONG DIRECTIONAL DIFFLUENCE AT UPPER LEVELS OVERTOP TIGHTENING LOW LEVEL FRONTAL BOUNDARY WILL SUPPORT AN EXPANDING AREA OF SHRA SPREADING INTO THE FCST AREA TONIGHT. LIKELY TO CATEGORICAL POPS LOOK ON TRACK. MODELS HAVE AND CONTINUE TO POINT TOWARD SW/W UPPER MI RECEIVING THE HEAVIEST RAINFALL WITH THAT AREA NEAR THE TRACK OF NW MOVING SFC WAVE. SO...AS IN PREVIOUS FCSTS... HIGHEST POPS WERE PAINTED IN THAT AREA. NOT OUT OF THE QUESTION THAT THERE MAY BE A FEW RUMBLES OF THUNDER GIVEN SHOWALTER INDEX FALLING TOWARD ZERO. MIN TEMPS WILL BE WELL ABOVE NORMAL GIVEN CLOUDS/DEEP MOISTURE. MINS SHOULD RANGE FROM THE MID 40S FAR W WHERE CAA WILL GET UNDERWAY OVERNIGHT TO THE MID 50S EAST. MAIN PUSH OF PCPN FROM TONIGHT WILL ROTATE NW OF THE AREA BY MORNING. SO THERE MAY BE SOMEWHAT OF A BREAK IN PCPN FOR A WHILE THU MORNING. HOWEVER...A SHORTWAVE ROTATING AROUND MIDLEVEL LOW WILL BE SWINGING N TOWARD ERN UPPER MI...AND SHOULD BRING ANOTHER ROUND OF GREATER SHRA COVERAGE INTO ESPECIALLY THE CNTRL AND ERN FCST AREA FOR THE AFTN. TEMP RISE THU WILL BE LIMITED BY CLOUDS/CAA. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 432 PM EDT WED OCT 17 2012 AN UPPER LOW WILL BE SPINNING OVER FAR SW WI AT 00Z FRI...WITH A SFC LOW TO THE N OF IT BUT S OF WRN LAKE SUPERIOR. A SHORTWAVE TROUGH WILL BE JUST SE OF THE CWA AT 00Z FRI...MOVING E TO W TO NEAR THE CENTER OF THE CWA BY 06Z FRI...THEN TO FAR WRN UPPER MI/FAR WRN LAKE SUPERIOR BY 12Z FRI. MODELS ARE IN GOOD AGREEMENT WITH THE SHORTWAVE...WITH ONLY MINOR TIMING DIFFERENCES BETWEEN THEM /THE GFS WAS USED WITH THE HIGHEST WEIGHT SINCE THE TIMING WAS BETWEEN THE FASTER NAM AND SLOWER ECMWF/. THE BEST CHANCES FOR WIDESPREAD PRECIP WILL BE FROM 00Z-06Z FRI. AFTER 06Z FRI...THE SFC LOW MOVING THROUGH WITH THE SHORTWAVE WILL QUICKLY MOVE TO SW WI. ALSO...BETWEEN 00Z-12Z FRI...THE MID/UPPER LOWS WILL BE STACKED JUST W OF LAKE MICHIGAN...WITH LOW LEVEL CYCLONIC FLOW UP THE LONG AXIS OF LAKE MICHIGAN. 850MB TEMPS WILL BE BETWEEN 0C AND -1C...SO LAKE ENHANCED RAIN WILL BE POSSIBLE INTO SCENTRAL AND ERN UPPER MI LATE THU NIGHT INTO FRI MORNING. SFC FEATURES BEGIN TO BREAK DOWN QUICKLY ON FRI AS THE SYSTEM MOVES TO SE LOWER MI BY LATE IN THE DAY. THE ECMWF IS ABOUT 12 HOURS SLOWER IN MOVING THE SYSTEM INTO QUEBEC ON SAT. EVEN SO...MODELS AGREE WITH SHOWING A SFC RIDGE MOVING INTO THE CWA AROUND 18Z SAT...WITH AN UPPER RIDGE PUSHING IN FROM THE NW. THE RIDGE WILL LEAD TO PRETTY QUIET WEATHER OVER THE WEEKEND...WITH ANY SIGNIFICANT CHANCES FOR RAIN BEING OVER THE FAR E AS THE LOW MOVES E OF THE CWA SAT...BUT THOSE CHANCES ARE SMALL. SINCE WARM AIR WILL NOT START TO RETURN TO THE AREA UNTIL THE SFC RIDGE MOVES THROUGH...SAT WILL SEE SIMILAR TEMPS TO FRI WITH HIGHS IN THE MID 40S TO MID 50S. SUN WILL BE WARMER AS 850MB TEMPS INCREASE TO 8-10C...LEADING TO HIGHS IN THE 50S AND 60S. AFTER SUN...SUBSTANTIAL MODEL DISAGREEMENT ON THE LOCATION OF A SFC RIDGE THAT MAY MOVE IN THE REGION. THE PROBLEM COMES FROM A SFC TROUGH/STATIONARY FRONT THAT WILL BE S OF THE RIDGE. THE GFS KEEPS THE RIDGE OVER THE CWA THROUGH NEXT WED...KEEPING US DRY...BUT THE ECMWF HAS THE TROUGH/FRONT OVER THE CWA THROUGH MUCH OF THE PERIOD...WHICH WOULD RESULT IN A MOST WET FORECAST. WITH HIGH MODEL DISAGREEMENT AND LOW RUN TO RUN CONTINUITY...USED A CONSENSUS OF MODELS IN THIS PORTION OF THE FORECAST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 136 AM EDT THU OCT 18 2012 EXPECT IFR CONDITIONS TO PREDOMINANT THRU MOST OF THIS MRNG WITH AREA OF RA/LLVL MSTR ASSOCIATED WITH DVLPG LO PRES NEAR MKX FCST TO ENVELOP THE AREA AS THE LO MOVES NW THRU NRN WI. ALTHOUGH ANOTHER DISTURBANCE MAY ROTATE INTO THE GRT LKS LATER TODAY AND BRING MORE -SHRA...SOME LLVL DRYING ARND THE DEPARTING LO IN MN WL LIKELY CAUSE AN IMPROVEMENT TO MVFR CONDITIONS. THE BEST CHC FOR MORE PERSISTENT IFR CONDITIONS WL BE AT IWD...WHERE THE LLVL DRYING WL BE MORE MINIMAL. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 432 PM EDT WED OCT 17 2012 A TRICKY FCST SHAPING UP TONIGHT INTO THU. DEEP SFC LOW NOW IN NW MN WILL BE REPLACED BY A NEW LOW PRES WAVE THAT WILL DEVELOP IN ERN WI TONIGHT AND THEN ROTATE NW TO VCNTY OF WRN LAKE SUPERIOR THU. IN RESPONSE TO THE NEW LOW...A BRIEF PERIOD OF E TO SE GALES MAY DEVELOP LATE TONIGHT INTO THU MORNING OVER CNTRL AND ERN LAKE SUPERIOR. GIVEN UNCERTAINTY IN HOW QUICK OR DEEP THE NEW LOW WILL BECOME BY THU MORNING...HELD OFF ON THE ISSUANCE OF A GALE WARNING FOR NOW. AS A TROUGH MOVES THROUGH THURSDAY NIGHT...SOUTHEAST WINDS OVER EASTERN LAKE SUPERIOR AND NORTHEAST WINDS OVER WESTERN LAKE SUPERIOR WILL GUST TO AROUND 25KTS. WINDS WILL THEN DIMINISH TO BELOW 20KTS FRIDAY THROUGH MONDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...TITUS AVIATION...KC MARINE...ROLFSON/TITUS
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
309 PM EDT THU OCT 18 2012 .SYNOPSIS... A STRONG WEATHER SYSTEM WILL BEGIN IMPACTING THE REGION LATER TONIGHT WITH RAIN GRADUALLY OVERSPREADING THE AREA AS THE OVERNIGHT HOURS PROGRESS. AT TIMES...RAIN MAY BECOME HEAVY AT TIMES LATER TONIGHT AND FRIDAY MORNING AS HIGH AMOUNTS OF MOISTURE INTERACT WITH A NORTHWARD MOVING WARM FRONT AND SURFACE LOW. RAIN WILL LINGER ACROSS THE REGION ON FRIDAY WITH THUNDERSTORMS BECOMING POSSIBLE FROM THE LOWER WYOMING VALLEY NORTH THROUGH THE POCONOS AND CATSKILLS. UNSETTLED WEATHER WILL THEN CONTINUE THROUGH THE UPCOMING WEEKEND AS THE UPPER LOW SLOWLY MOVES OVER THE REGION. && .NEAR TERM /THROUGH FRIDAY/... LATEST VIS SATELLITE IMAGERY CONTINUES TO SHOW CLOUDS STREAMING NORTHEAST FROM THE LWR OHIO VALLEY THIS AFTERNOON AS COLD/OCCLUDED FRONTAL BOUNDARY ADVANCES EAST. ALOFT...WATER VAPOR IMAGERY SHOWING A DEEPLY WOUND- UP UPPER LOW ACROSS THE UPPER MISS RVR VLY WITH RUC POTENTIAL VORTICITY COMPOSITES INDICATING THE THE UPPER PV ANOMALY EXTENDS DOWN TO NEAR 500 MB ACROSS THE OHIO/MISS RVR CONFLUENCE REGION. THIS LEAD WAVE WILL CONTINUE MOVING NORTHEAST OVERNIGHT WHICH WILL ULTIMATELY HELP PROPEL THE AFOREMENTIONED COLD/OCCLUDED FRONT EAST INTO OUR FCST AREA. LATEST RADAR TRENDS NOW SHOWING INITIAL FRONTAL WAVE RAIN BAND SLOWLY LIFTING NORTHEAST THROUGH EASTERN OHIO THIS AFTERNOON WHICH WITH TIME SHOULD BEGIN ENTERING OUR WESTERN ZONES AFTER 00Z THIS EVENING. CLOSER TO THE SFC...A STRONG PRESSURE GRADIENT BETWEEN THIS DEEPLY WOUND-UP SYSTEM AND DEPARTING HIGH PRESSURE OFF THE EAST COAST HAS ALLOWED FOR STRONG SOUTHEASTERLY WINDS THIS AFTERNOON WITH LATEST OBSERVATIONS SHOWING GUSTS AS HIGH AS 35 KTS ACROSS THE REGION. AS HAS THE BEEN THE CONCERN IN RECENT DAYS...12Z MODEL GUIDANCE CONTINUES TO ADVERTISE FAVORABLE CONDITIONS FOR A DECENT RAINFALL EVENT ACROSS MUCH OF CENTRAL NY AND NE PA BEGINNING TONIGHT AS INITAL PV ANOMALY AND SFC FRONT TRANSLATE NORTHEAST OVER THE AREA. AHEAD OF THESE FEATURES...STRONG MOISTURE ADVECTION CHARACTERIZED H925 V-WIND COMPONENTS ON THE ORDER OF 2-3 STANDARD DEVIATIONS ABOVE NORMAL WILL HELP INCREASE PWAT VALUES TO WELL OVER 1 INCH ACROSS THE EASTERN ZONES BY 12Z FRI. AS THIS OCCURS...MODELS NOW SHOWING A SECONDARY FRONTAL WAVE AND CORRESPONDING WARM FRONT MOVING NORTH ALONG THE OCCLUDED FRONT OVERNIGHT WHICH WILL EFFECTIVLY HELP STALL THE MAIN OCCLUDED FRONT WITH TIME ACROSS OUR FCST AREA EARLY FRI. BY 15Z...MODELS INDICATE THAT THE TRIPLE POINT WILL RESIDE OVER OR REGION WITH EASTERN ZONES EFFECTIVELY BECOMING PLACED IN MODIFYING WARM SECTOR AIR. MODELS CONTINUE TO SUGGEST THE DEVELOPMENT OF WEAK INSTABILITY AFTER 12Z FRI AS DEWPOINTS CLIMB INTO THE MIDDLE TO UPPER 50S...AND POSSIBLY LOWER 60S ACROSS OUR FAR SOUTHEAST. MEANWHILE ALOFT...MODELS STILL ADVERTISING THE ENTRANCE OF A MID-LEVEL JET BY LATE MORNING WHICH WILL INCREASE THE VERTICAL WIND SHEAR PROFILE ACROSS THE REGION. CONSIDERING THAT SUCH STRONG WIND FIELD WILL BE IN PLACE (0-6 KM BULK SHEAR WELL OVER 50 KTS)...DEVELOPING CONVECTION COULD EASILY BE SHEARED APART AS IT FIRES. THAT SAID...WITH STRONGER INSTABILITY SUGGESTED WITH TODAY/S RUNS...HAVE ELECTED TO REINTRODUCE A THUNDER MENTION FOR FRI FROM THE LWR WYOMING VLY NORTH THROUGH THE POCONOS AND CATSKILLS. WITH RESPECT TO FCST QPF AMOUNTS...HPC GUIDANCE CONTINUES TO ADVERTISE CLOSE TO 2" ACROSS THE EASTERN POCONOS AND CATSKILLS WHERE MOIST SOUTHEAST WINDS WILL INTERACT WITH UPSLOPE TERRAIN INFLUENCES. FOR NOW HAVE FOLLOWED BOTH HPC AND RFC QPF GUIDANCE WHICH KEEPS THE HIGHEST AMOUNTS ACROSS THE EASTERN HALF OF THE CWA. BY LATE MORNING...MODELS INDICATE THAT A WELL DEVELOPED DRY SLOT WILL BEGIN WORKING INTO OUR WESTERN ZONES WHICH SHOULD RESULT IN RAIN COMING TO AN END FROM WEST TO EAST DURING THE LATE MORNING/EARLY AFTERNOON HRS. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... UNSETTLED WX EXPECTED TO CONTINUE RIGHT THROUGH THE WEEKEND AS UPPER LOW CONTINUES TO PINWHEEL ACROSS THE REGION BOTH FRIDAY NIGHT AND SATURDAY. FOR ALL INTENSIVE PURPOSES...MAIN RAIN BAND SHOULD BE EXITING TO THE EAST BY FRIDAY EVENING AS NORTHWARD MOVING FRONTAL WAVE FRIDAY AFTERNOON FINALLY EXITS TO THE NORTHEAST. WITH AFOREMENTIONED DRY SLOT LINGERING...HAVE MAINTAINED SLGT CHC TO CHC MENTION FOR POPS FRI NGT. FOR SATURDAY...UPPER WAVE TO INCH EVER SO CLOSER TO THE REGION WITH THE NEXT ROUND OF SHORTWAVE ENERGY EXPECTED TO LEAD TO ADDITIONAL SHWRS LATE SAT MORNING/AFTERNOON. RIGHT NOW BEST POTENTIAL FOR REDEVELOPING SHWRS APPEAR ACROSS THE NORTHERN ZONES WHERE COLD TEMPS ALOFT WILL COMBINE WITH BEST FORCING FOR ASCENT FROM THE MAIN SFC LOW FCST TO LIFT FROM THE CENTRAL LAKES INTO SOUTHERN ONTARIO. UPPER LOW TO FINALLY BEGIN LIFTING NORTHEAST OF THE REGION SAT NIGHT/EARLY SUN AS HEIGHTS BUILD ACROSS THE NORTHERN MISS RVR VLY/SOUTHERN CANADIAN PRAIRIE PROVINCES. BEHIND THE FEATURE...H85 TEMPS ONLY DROP TO NEAR 0C WHICH MAY RESULT IN SCATTERED LAKE EFFECT RAIN SHWRS JUST TO OUR NORTH IN SUSTAINED SOUTHWEST LOW- LEVEL FLOW. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... DURING THE EXTENDED PERIOD MEDIUM RANGE MODELS ARE IN AGREEMENT THAT THE UPPER LEVEL TROF OVER THE NORTHEAST WILL BE REPLACED BY RISING HEIGHTS AND DEVELOPMENT OF AN UPPER LEVEL RIDGE. AT THE SURFACE THINGS ARE A BIT MORE TRICKY WITH LOW PRES MOVING THROUGH THE UPPER GREAT LAKES WITH POSSIBLE FROPA TUESDAY NIGHT. GENERALLY FOLLOWED HPC GUIDANCE. SUNDAY EVENING WILL INCLUDE SLIGHT CHC POPS FAR NRN CWA ON BACK SIDE OF UPPER LEVEL TROF THEN DRY. DRY WEATHER IS EXPECTED MONDAY THROUGH MUCH OF MONDAY NIGHT THEN CHC/SLIGHT CHC POPS TUESDAY THROUGH WEDNESDAY DUE TO PASSING COLD FRONT AND NORTHWEST FLOW BEHIND BOUNDARY. DRY WEATHER WILL RETURN WED NIGHT/THURSDAY AS SFC HIGH BUILDS DOWN FROM CANADA. TEMPS WILL BE 5-10 DEGREES ABOVE NORMAL. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... VFR CONDITIONS WILL CONTINUE ACROSS THE TERMINALS UNTIL LATE THIS EVENING WHEN AN OCCLUSION WILL QUICKLY LOWER THE FLIGHT CATEGORY. LOW MVFR CONDITIONS DUE VSBYS/CIGS IN LIGHT RAIN WILL SPREAD OVER THE REGION BETWEEN 03Z-05Z. AT KITH/KELM/KBGM/KAVP, IFR CONDITIONS WILL BE POSSIBLE BETWEEN 08Z-12Z DUE TO LOWER CIGS AND POSSIBLE VSBY RESTRICTIONS IN MODERATE RAIN. THIS BOUNDARY WILL LIFTS THROUGH THE REGION DURING THE MID MORNING THROUGH EARLY AFTERNOON PERIOD BUT MVFR RESTRICTIONS WILL PERSIST. GUSTY SE WINDS AT 15-25 KNOTS BECOMING 10 KNOTS OVERNIGHT THEN SHIFTING THE NORTHWEST LATE IN THE TAF PERIOD. OUTLOOK... FRI NIGHT THROUGH SAT...MVFR IN PROLONGED SHWR ACTIVITY. SUN AND MON...MAINLY VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...CMG NEAR TERM...CMG SHORT TERM...CMG LONG TERM...RRM AVIATION...RRM
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1006 PM EDT FRI OCT 19 2012 .SYNOPSIS... A WEAK REINFORCING COLD FRONT WILL CROSS THE MIDDLE ATLANTIC STATES THROUGH EARLY SATURDAY...FOLLOWED BY HIGH PRESSURE THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH SATURDAY NIGHT/... AS OF 1005 PM FRIDAY... THE LEAD LOW LEVEL FRONTAL ZONE HAD MOVED JUST EAST OF THE NC OUTER BANKS AT 02Z...WHILE A REINFORCING COLD FRONT HAD MOVED TO THE VICINITY OF THE BLUE RIDGE. THIS TRAILING/REINFORCING COLD FRONT WILL PRODUCE A BRIEF PERIOD OF LOW LEVEL CAA IN THE WEST TOWARD DAYBREAK...THEN FOR A FEW HOURS SHORTLY THEREAFTER ACROSS THE REMAINDER OF CENTRAL NC. OTHERWISE...THE NIGHT WILL BE CLEAR WITH ALTERNATING PERIODS OF CALM AND SOUTHWESTERLY STIRRING IN ADVANCE OF THE TRAILING FRONT...WHICH WILL RESULT IN CONTINUED WIDE-RANGING AND VARIABLE TEMPERATURES -- HIGHLIGHTED AT 02Z BY 45 DEGREES AT K5W8 AND A PAIR OF 60S AT KINT AND KFAY -- OVERNIGHT. PROVIDED EVERYONE HAS AT LEAST A BRIEF PERIOD OF CALM AS EXPECTED...LOWS WILL BOTTOM IN THE 41 TO 48 DEGREE RANGE. -MWS AS OF 220 PM FRIDAY... THE COLD FRONT EXTENDING SOUTH FROM THE OCCLUDED LOW OVER THE GREAT LAKES HAS BEEN MOVING VERY SLOWLY ACROSS THE CWA TODAY...STRUGGLING TO GET PAST US HWY 1 THROUGH NOON. HOWEVER...DEWPOINTS ARE FINALLY BEGINNING TO MIX OUT MORE EFFICIENTLY BEHIND THE FRONT...AND THE SHARP DEWPOINT/INSTABILITY GRADIENT IS SHIFTING EAST INTO THE COASTAL PLAIN. DRIER AIR ALOFT NOTED IN WATER VAPOR IMAGERY IS LIMITING CUMULUS DEVELOPMENT TO A NARROW STRIP ALONG A REGION CONFLUENCE FROM LEXINGTON TO ROXBORO. HRRR RUNS HAVE BEEN SHOWING A FEW ISOLATED SHOWERS OVER THE NORTHERN PIEDMONT AFTER 20Z...BUT THIS SEEMS OVERDONE GIVEN THE AMOUNT OF DRY AIR ALOFT. OTHERWISE...SOUTHWESTERLY WIND GUSTS ARE STARTING TO DEVELOP...MOSTLY IN THE TEENS THUS FAR...BUT A FEW MAY REACH 20-25KT BEFORE SUNSET. TONIGHT... A SHORTWAVE IN THE BASE OF THE UPPER TROUGH WILL SWING ACROSS GA/SC...WITH CONTINUED DRY CONDITIONS AND MOSTLY CLEAR SKIES ACROSS CENTRAL NC. A LIGHT WESTERLY WIND MAY LIMIT FULL RADIATIONAL COOLING...MID TO UPPER 40S WEST TO EAST. SATURDAY AND SATURDAY NIGHT... BROAD CYCLONIC UPPER LEVEL FLOW WILL CONTINUE OVER THE AREA AS THE GREAT LAKES UPPER LOW BEGINS TO OPEN UP AND LIFT NORTHEAST. A SPEED MAX DIVING THROUGH THE BACK SIDE OF THE UPPER TROUGH WILL SHARPEN THE TROUGH AXIS AS IT CROSSES THE AREA SATURDAY EVENING. THE ADDED DPVA MAY BE ENOUGH TO HELP ENHANCE SOME LATE AFTERNOON CLOUD COVER AS RH CROSS SECTIONS SHOW A LAYER OF MOISTURE AT THE TOP OF THE BOUNDARY LAYER (5-8KT FT). WITH WEAK THERMAL ADVECTION/FLOW AHEAD OF THE TROUGH AXIS...WILL USE 1000-850MB THICKNESSES FOR HIGHS...YIELDING UPPER 60S TO LOWER 70S. ONCE THE TROUGH AXIS MOVES EAST...NORTHWESTERLY FLOW WILL DEVELOP ALOFT SATURDAY NIGHT. THIS TYPE OF PATTERN SUGGESTS THE POTENTIAL FOR OROGRAPHIC CIRRUS...ALTHOUGH THE NAM/GFS SHOW THE BEST UPPER LEVEL MOISTURE DIVING JUST SOUTH OF THE APPALACHIANS. WITHOUT CIRRUS...THE ARRIVAL OF BETTER LOW LEVEL COLD ADVECTION BEHIND THE TROUGH AXIS SHOULD LEAD TO LOWS IN THE LOW TO MID 40S. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 230 PM FRIDAY... CLOSED UPPER LOW AND ASSOCIATED UPPER TROUGH OVER THE EASTERN US WILL LIFT NORTHEASTWARD INTO SOUTHEASTERN CANADA DURING THE DAY ON SUNDAY...WITH STRONG SYNOPTIC SCALE SUBSIDENCE SETTLING OVER THE REGION IN IT WAKE AS THE UPSTREAM RIDGE OVER THE CENTRAL US SHIFTS EASTWARD INTO THE AREA. THIS WILL RESULT IN CONTINUED DRY CONDITIONS WITH A RAPID WARM-UP/MODERATION FROM BELOW NORMAL DAYTIME TEMPERATURES IN THE MID TO UPPER 60S ON SUNDAY TO ABOVE NORMAL READINGS IN THE LOWER TO MID 70S BY MONDAY. STRONG RADIATIONAL COOLING AND A DRY AIRMASS IN PLACE WILL STILL ALLOW FOR CHILLY MORNING LOWS BOTH MORNINGS. LOWS IN THE LOWER TO MID 40S. & .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 230 PM FRIDAY... BROAD SUBTROPICAL RIDGING WILL ENVELOP THE SOUTHEASTERN/EASTERN US THROUGH THE UPCOMING WORK WEEK...DOWNSTREAM OF THE WESTERN/CENTRAL US TROUGH. WHILE THERE ARE SOME GROSS DIFFERENCES WITH HOW NWP MODELS HANDLE THE EVOLUTION OF THE WESTERN US TROUGH AND ASSOCIATED REX BLOCK...CENTRAL NC LOOKS TO BE WELL UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE TO CLOSE THE WORK WEEK...KEEPING SHORTWAVE DISTURBANCES AT ARMS LENGTH...TRACKING NORTHEAST THROUGH THE PLAINS...THROUGH THE THE GREAT LAKES AND THEN INTO SOUTHEASTERN CANADA. THIS WILL RESULT IN WARM AND QUITE WEATHER CONDITIONS("INDIAN SUMMER")THROUGH THE WEEK. DAYTIME HIGHS WELL IN THE MID TO UPPER 70S. LOWS IN THE UPPER 40S TO LOWER 50S. && .AVIATION /00Z SATURDAY THROUGH TUESDAY/... AS OF 805 PM FRIDAY... COLD FRONT CURRENTLY APPROACHING THE CAROLINA COAST WILL MOVE OUT OF THE AREA TONIGHT. SKIES HAVE CLEARED AND GUSTINESS FROM THE AFTERNOON SUBSIDED WITH SUNSET. WINDS WILL REMAIN LIGHT OVERNIGHT FROM THE WSW. THE COMBINATION OF CALM TO LIGHT SOUTHWESTERLY SURFACE WINDS AND A 30 KT LOW LEVEL JET CENTERED AROUND 2000 FT WILL PRODUCE CONDITIONS JUST SHY OF LOW LEVEL WIND SHEAR CRITERIA OVERNIGHT. HIGH PRESSURE WILL MOVE IN FROM THE SOUTHWEST SATURDAY AND REMAIN OVER THE AREA THROUGH MIDWEEK...PROVIDING AN EXTENDED PERIOD OF VFR CONDITIONS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MWS NEAR TERM...MWS/BLS SHORT TERM...CBL LONG TERM...CBL AVIATION...SEC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
806 PM EDT FRI OCT 19 2012 .SYNOPSIS... A COLD FRONT OVER THE COASTAL PLAIN WILL PUSH OFFSHORE TONIGHT. HIGH PRESSURE WILL THEN BUILD SLOWLY INTO THE CAROLINAS AND SOUTHERN VIRGINIA BEHIND THE FRONT AND LINGER OVER THE REGION THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH SATURDAY NIGHT/... AS OF 220 PM FRIDAY... THE COLD FRONT EXTENDING SOUTH FROM THE OCCLUDED LOW OVER THE GREAT LAKES HAS BEEN MOVING VERY SLOWLY ACROSS THE CWA TODAY...STRUGGLING TO GET PAST US HWY 1 THROUGH NOON. HOWEVER...DEWPOINTS ARE FINALLY BEGINNING TO MIX OUT MORE EFFICIENTLY BEHIND THE FRONT...AND THE SHARP DEWPOINT/INSTABILITY GRADIENT IS SHIFTING EAST INTO THE COASTAL PLAIN. DRIER AIR ALOFT NOTED IN WATER VAPOR IMAGERY IS LIMITING CUMULUS DEVELOPMENT TO A NARROW STRIP ALONG A REGION CONFLUENCE FROM LEXINGTON TO ROXBORO. HRRR RUNS HAVE BEEN SHOWING A FEW ISOLATED SHOWERS OVER THE NORTHERN PIEDMONT AFTER 20Z...BUT THIS SEEMS OVERDONE GIVEN THE AMOUNT OF DRY AIR ALOFT. OTHERWISE...SOUTHWESTERLY WIND GUSTS ARE STARTING TO DEVELOP...MOSTLY IN THE TEENS THUS FAR...BUT A FEW MAY REACH 20-25KT BEFORE SUNSET. TONIGHT... A SHORTWAVE IN THE BASE OF THE UPPER TROUGH WILL SWING ACROSS GA/SC...WITH CONTINUED DRY CONDITIONS AND MOSTLY CLEAR SKIES ACROSS CENTRAL NC. A LIGHT WESTERLY WIND MAY LIMIT FULL RADIATIONAL COOLING...MID TO UPPER 40S WEST TO EAST. SATURDAY AND SATURDAY NIGHT... BROAD CYCLONIC UPPER LEVEL FLOW WILL CONTINUE OVER THE AREA AS THE GREAT LAKES UPPER LOW BEGINS TO OPEN UP AND LIFT NORTHEAST. A SPEED MAX DIVING THROUGH THE BACK SIDE OF THE UPPER TROUGH WILL SHARPEN THE TROUGH AXIS AS IT CROSSES THE AREA SATURDAY EVENING. THE ADDED DPVA MAY BE ENOUGH TO HELP ENHANCE SOME LATE AFTERNOON CLOUD COVER AS RH CROSS SECTIONS SHOW A LAYER OF MOISTURE AT THE TOP OF THE BOUNDARY LAYER (5-8KT FT). WITH WEAK THERMAL ADVECTION/FLOW AHEAD OF THE TROUGH AXIS...WILL USE 1000-850MB THICKNESSES FOR HIGHS...YIELDING UPPER 60S TO LOWER 70S. ONCE THE TROUGH AXIS MOVES EAST...NORTHWESTERLY FLOW WILL DEVELOP ALOFT SATURDAY NIGHT. THIS TYPE OF PATTERN SUGGESTS THE POTENTIAL FOR OROGRAPHIC CIRRUS...ALTHOUGH THE NAM/GFS SHOW THE BEST UPPER LEVEL MOISTURE DIVING JUST SOUTH OF THE APPALACHIANS. WITHOUT CIRRUS...THE ARRIVAL OF BETTER LOW LEVEL COLD ADVECTION BEHIND THE TROUGH AXIS SHOULD LEAD TO LOWS IN THE LOW TO MID 40S. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 230 PM FRIDAY... CLOSED UPPER LOW AND ASSOCIATED UPPER TROUGH OVER THE EASTERN US WILL LIFT NORTHEASTWARD INTO SOUTHEASTERN CANADA DURING THE DAY ON SUNDAY...WITH STRONG SYNOPTIC SCALE SUBSIDENCE SETTLING OVER THE REGION IN IT WAKE AS THE UPSTREAM RIDGE OVER THE CENTRAL US SHIFTS EASTWARD INTO THE AREA. THIS WILL RESULT IN CONTINUED DRY CONDITIONS WITH A RAPID WARM-UP/MODERATION FROM BELOW NORMAL DAYTIME TEMPERATURES IN THE MID TO UPPER 60S ON SUNDAY TO ABOVE NORMAL READINGS IN THE LOWER TO MID 70S BY MONDAY. STRONG RADIATIONAL COOLING AND A DRY AIRMASS IN PLACE WILL STILL ALLOW FOR CHILLY MORNING LOWS BOTH MORNINGS. LOWS IN THE LOWER TO MID 40S. & .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 230 PM FRIDAY... BROAD SUBTROPICAL RIDGING WILL ENVELOP THE SOUTHEASTERN/EASTERN US THROUGH THE UPCOMING WORK WEEK...DOWNSTREAM OF THE WESTERN/CENTRAL US TROUGH. WHILE THERE ARE SOME GROSS DIFFERENCES WITH HOW NWP MODELS HANDLE THE EVOLUTION OF THE WESTERN US TROUGH AND ASSOCIATED REX BLOCK...CENTRAL NC LOOKS TO BE WELL UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE TO CLOSE THE WORK WEEK...KEEPING SHORTWAVE DISTURBANCES AT ARMS LENGTH...TRACKING NORTHEAST THROUGH THE PLAINS...THROUGH THE THE GREAT LAKES AND THEN INTO SOUTHEASTERN CANADA. THIS WILL RESULT IN WARM AND QUITE WEATHER CONDITIONS("INDIAN SUMMER")THROUGH THE WEEK. DAYTIME HIGHS WELL IN THE MID TO UPPER 70S. LOWS IN THE UPPER 40S TO LOWER 50S. && .AVIATION /00Z SATURDAY THROUGH TUESDAY/... AS OF 805 PM FRIDAY... COLD FRONT CURRENTLY APPROACHING THE CAROLINA COAST WILL MOVE OUT OF THE AREA TONIGHT. SKIES HAVE CLEARED AND GUSTINESS FROM THE AFTERNOON SUBSIDED WITH SUNSET. WINDS WILL REMAIN LIGHT OVERNIGHT FROM THE WSW. LOW LEVEL WIND SHEAR MAY INCREASE TONIGHT WITH WINDS AT 2000 FT NEAR 30 KTS. HIGH PRESSURE WILL MOVE IN FROM THE SOUTHWEST SATURDAY AND REMAIN OVER THE AREA THROUGH MIDWEEK... PROVIDING AN EXTENDED PERIOD OF VFR CONDITIONS. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLS NEAR TERM...BLS SHORT TERM...CBL LONG TERM...CBL AVIATION...SEC
AREA FORECAST DISCUSSION
NWS RALEIGH NC
405 PM EDT THU OCT 18 2012 .SYNOPSIS... A COLD FRONT WILL CROSS THE REGION LATE TONIGHT INTO EARLY FRIDAY. HIGH PRESSURE WILL BUILD INTO THE CAROLINAS AND SOUTHERN VIRGINIA IN THE WAKE OF THE FRONT AND LINGER OVER THE AREA THROUGH SUNDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS OF 305 PM THURSDAY... CLOUDS WILL INCREASE IN COVERAGE FROM WEST TO EAST THIS EVENING AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. AS OF THE 12Z UPPER AIR ANALYSIS...UPPER LEVEL LOW PRESSURE WAS LOCATED OVER SRN MN/NRN IA WITH THE TROUGH EXTENDING SOUTH INTO THE LOWER MS RIVER VALLEY. BEST HEIGHT FALLS ARE STILL WELL TO THE NW...WITH A 140KT JET AT 250 MB OVER AR EXPECTED TO MOVE EASTWARD OVER THE APPALACHIANS LATER TODAY. 16Z SURFACE ANALYSIS PLACES THE LOW OVER WI AND THE FRONT EXTENDING EAST AND THEN SOUTH THROUGH THE OH AND TN VALLEYS. AS THIS FRONT MIGRATES EASTWARD TODAY...WILL SEE INCREASING LOW-LEVEL MOISTURE AND CLOUDS. AS FOR THE CONVECTION...THE 12Z NCEP WRF NMM DEVELOPS A LINE OF SHOWERS OVER THE WESTERN PORTIONS OF THE AREA BETWEEN 21Z AND 00Z...MAKING IT TO APPROX THE TRIANGLE AREA BEFORE LIFTING NE AND DISSIPATING. THE 00Z NSSL WRF ARW SHOWS A SIMILAR SCENARIO. GIVEN THE CURRENT SPC ANALYSES SHOWING INCREASING LOW-LEVEL LAPSE RATES AHEAD OF THE DEVELOPING LINE OF SHOWERS AND EFFECTIVE BULK SHEAR VALUES 45-50 KTS OVER THE MTS...CURRENTLY ABOUT 20 KTS OVER CENTRAL NC. ALSO...MUCAPE VALUES ARE AROUND 500 J/KG... MAINLY ACROSS THE SOUTH. RUC ANALYSIS SHOWS BULK SHEAR VALUES OVER CENTRAL NC INCREASING TO 50-60 KTS...WITH CAPE OF 500-1000 J/KG...MAINLY ACROSS THE WEST. THIS SUPPORTS THE POTENTIAL FOR THUNDERSTORMS TO DEVELOP ACROSS THE WESTERN HALF OF THE AREA TONIGHT...WITH AN ISOLATED STRONG TO SEVERE STORM POSSIBLE. MAIN THREAT WOULD BE DAMAGING WINDS. SHOWERS AND ISOLATED STORMS ARE ALSO POSSIBLE ALONG THE COASTAL PLAIN AHEAD OF THE MAIN LINE OF SHOWERS AND STORMS THIS EVENING. HOW QUICKLY THE SHOWERS AND CLOUDS MOVE OUT OF THE AREA WILL IMPACT THE LOW TEMPS FOR TONIGHT...BUT GENERALLY LOOKING AT NEAR 50 DEGREES NW TO LOW 60S SE. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... AS OF 240 PM THURSDAY... FRIDAY... LARGE UPPER LOW OVER THE UPPER MIDWEST WILL MIGRATE EAST OVER THE GREAT LAKES ON FRIDAY. THE COLD FRONT TO SLOWLY CROSS CENTRAL NC TONIGHT IS FORECAST TO MOVE FROM ROUGHLY US HWY 1 AT 12Z TO WELL EAST OF I-95 BY 18Z. EARLY IN THE DAY...FORCING FOR ACCENT WILL MAINLY BE LIMITED TO UPPER DIVERGENCE IN THE RIGHT ENTRANCE OF THE DEPARTING 120KT UPPER JET...WITH ONLY 30M HEIGHT FALLS AND INCREASINGLY STABLE AND DRY AIR ALOFT. ANY REDEVELOPMENT OF SHOWERS DURING THE FIRST HALF OF THE DAY WILL BE TIED TO WEAK FRONTAL CONVERGENCE OVER THE COASTAL PLAIN...BUT EVEN THAT IS FORECAST TO WEAKEN AS THE FLOW BECOMES MORE UNIDIRECTIONAL AND SOUTHWESTERLY. WITH CLEARING SKIES AND A MODEST HEIGHT GRADIENT BEHIND THE FRONT...FORECAST SOUNDINGS SHOW BOUNDARY LAYER MIXING...GREATEST IN THE WEST...LEADING TO SOUTHWESTERLY WIND GUSTS OF UP TO 20-25KT DURING THE AFTERNOON. A LOW LEVEL TRAJECTORY OUT OF THE SOUTHWEST BEHIND THE FRONT WILL NOT LEAD TO A LARGE COOL DOWN BASED ON THE UPSTREAM AIRMASS...WITH MOST GUIDANCE SHOWING HIGHS OF 70-78 NORTHWEST TO SOUTHEAST. FRIDAY NIGHT... OTHER THAN THE POTENTIAL FOR MID CLOUDS PASSING THROUGH THE BASE OF THE UPPER LEVEL LOW...WHICH WILL BEGIN TO OPEN UP BY SATURDAY MORNING...SKIES SHOULD BE MOSTLY CLEAR. AGAIN THERE IS NO REAL STRONG COLD ADVECTION SATURDAY NIGHT AND LOWS SHOULD SETTLE JUST BELOW NORMAL INTO THE MID TO UPPER 40S FOR MOST AREAS. SATURDAY THROUGH SUNDAY...... THE MEAN TROUGH AXIS IS FORECAST TO CROSS THE APPALACHIANS AS THE UPPER LOW OPENS AND LIFTS NORTHEASTWARD ON SATURDAY. THE COMBINATION OF UPSTREAM MOISTURE AND THE COLDEST AIR ALOFT PASSING OVERHEAD SHOULD LEAD TO ENHANCED STRATOCU IN THE LEE OF THE MOUNTAINS DURING THE AFTERNOON. 1000-850MB THICKNESSES HOVER IN THE 1360S DURING THE DAY WITH A WEAK DOWNSLOPE FLOW POTENTIALLY OFFSETTING WEAK COLD ADVECTION. THUS...WILL KEEP HIGHS WITHIN A COUPLE DEGREES OF THOSE BASED ON THICKNESSES...66-73 NORTHWEST TO SOUTHEAST. LOWS SATURDAY NIGHT IN THE LOW TO MID 40S UNDER MOSTLY CLEAR SKIES...ALTHOUGH FORECAST SOUNDINGS SUGGEST CONDITIONS COULD BE FAVORABLE FOR SOME OROGRAPHIC CIRRUS. HIGH PRESSURE WILL BEGIN TO BUILD INTO THE AREA FROM THE SOUTHWEST SUNDAY WITH MOSTLY SUNNY SKIES AND HIGHS AROUND 70S. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 250 PM THURSDAY... OVERALL...THIS PERIOD WILL BE DOMINATED BY HIGH PRESSURE BOTH AT THE SURFACE AND ALOFT. SURFACE HIGH PRESSURE WILL SETTLE RIGHT OVER THE REGION...WHILE A MID LEVEL RIDGE WILL BUILD IN FROM THE GULF COAST AREA. THIS WILL RESULT IN A PROLONGED PERIOD OF DRY CONDITIONS. AS HEIGHTS GRADUALLY INCREASE THROUGHOUT THE PERIOD...TEMPS WILL SLOWLY MODERATE...WITH HIGHS TRENDING TO ABOVE NORMAL. HOWEVER...WITH FAIRLY DRY AIR IN PLACE AND MOSTLY CLEAR SKIES...OUR DIURNAL RANGE SHOULD BE LARGE...WITH OVERNIGHT LOWS ABLE TO DROP OFF INTO THE 40S. A BACK DOOR FRONT MAY APPROACH THE REGION LATE IN THE PERIOD...BUT AS OF NOW MODELS SHOW LITTLE IMPACT TO THE AREA. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... AS OF 200 PM THURSDAY... 24 HOUR TAF PERIOD: CHALLENGING TAF FORECAST WITH REGARD TO TIMING OF PRECIP AHEAD OF A COLD FRONT MOVING IN FROM THE WEST OVERNIGHT AND INTO FRIDAY. BEST CHANCE OF RAIN BEGINNING AROUND 00Z AT KINT AND KGSO...AND CLOSER TO 03Z-05Z ELSEWHERE. STILL QUITE A BIT OF UNCERTAINTY WITH REGARD TO COVERAGE AND INTENSITY OF PRECIP AS WELL. VISBYS COULD GO DOWN TO MVFR/IFR WHERE PRECIP IS OCCURRING...AND MVFR/IFR CIGS AND VISBYS WITH FOG/STRATUS CONDITIONS BEGINNING AFTERWARD. CEILINGS HAVE ALREADY GONE TO MVFR AT KINT AND KGSO AND ASIDE FROM SOME BRIEF SCATTERING...WILL LIKELY REMAIN MVFR THE REMAINDER OF THE AFTERNOON. CEILINGS AT THE REMAINING TERMINALS SHOULD REMAIN LOW END VFR... POTENTIALLY DROPPING TO HIGH END MVFR BEFORE MIDNIGHT. WINDS ARE EXPECTED TO BE GUSTY AT ALL TERMINALS THIS AFTERNOON...MAINLY OUT OF THE SOUTH. CIG AND VISBY RESTRICTIONS SHOULD START CLEARING UP AFTER SUNRISE FRIDAY AS DRIER AIR MOVES IN BEHIND THE FRONT. FRIDAY NIGHT THROUGH TUESDAY: WITH THE EXCEPTION OF SOME LINGERING SHOWERS ALONG THE COASTAL PLAIN FRIDAY AFTERNOON...THE PRECIP AND OVERCAST SKIES SHOULD BE OUT OF CENTRAL NC BY 15Z AND 21Z FRIDAY...RESPECTIVELY AS THE COLD FRONT PUSHES THROUGH THE AREA. WINDS WILL BE GUSTY BEHIND THE FRONT... POTENTIALLY 20 KTS OR MORE AT TIMES. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT AND LINGER THROUGH TUESDAY...RESULTING IN VFR CONDITIONS FOR THE REMAINDER OF THE PERIOD. && .FIRE WEATHER... A COLD FRONT WILL CROSS CENTRAL NC LATE TONIGHT AND EARLY FRIDAY. BEHIND THE FRONT...DEWPOINTS ARE FORECAST TO MIX OUT INTO THE LOW TO MID 30S...WHILE TEMPS WILL BE RELATIVELY WARM FOR A POST-FRONTAL AIRMASS. THIS WILL CAUSE RH VALUES TO DROP BELOW 30 PERCENT OVER MUCH OF THE WESTERN PIEDMONT. CONCURRENTLY...SOUTHWESTERLY WIND GUSTS WILL LIKELY REACH THE 20-25MPH RANGE FRIDAY AFTERNOON. DESPITE THESE CONDITIONS...THE NCFS REPORTS RELATIVELY HIGH FUEL MOISTURE AT THIS TIME...AND THUS NO STATEMENTS REGARDING FIRE WEATHER WILL BE ISSUED FOR FRIDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...BLS NEAR TERM...KC SHORT TERM...BLS LONG TERM...KRR AVIATION...KC FIRE WEATHER...BLS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
310 PM EDT THU OCT 18 2012 .SYNOPSIS... A COLD FRONT WILL CROSS THE REGION LATE TONIGHT INTO EARLY FRIDAY. HIGH PRESSURE WILL BUILD INTO THE CAROLINAS AND SOUTHERN VIRGINIA IN THE WAKE OF THE FRONT AND LINGER OVER THE AREA THROUGH SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 305 PM THURSDAY... CLOUDS WILL INCREASE IN COVERAGE FROM WEST TO EAST THIS EVENING AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. AS OF THE 12Z UPPER AIR ANALYSIS...UPPER LEVEL LOW PRESSURE WAS LOCATED OVER SRN MN/NRN IA WITH THE TROUGH EXTENDING SOUTH INTO THE LOWER MS RIVER VALLEY. BEST HEIGHT FALLS ARE STILL WELL TO THE NW...WITH A 140KT JET AT 250 MB OVER AR EXPECTED TO MOVE EASTWARD OVER THE APPALACHIANS LATER TODAY. 16Z SURFACE ANALYSIS PLACES THE LOW OVER WI AND THE FRONT EXTENDING EAST AND THEN SOUTH THROUGH THE OH AND TN VALLEYS. AS THIS FRONT MIGRATES EASTWARD TODAY...WILL SEE INCREASING LOW-LEVEL MOISTURE AND CLOUDS. AS FOR THE CONVECTION...THE 12Z NCEP WRF NMM DEVELOPS A LINE OF SHOWERS OVER THE WESTERN PORTIONS OF THE AREA BETWEEN 21Z AND 00Z...MAKING IT TO APPROX THE TRIANGLE AREA BEFORE LIFTING NE AND DISSIPATING. THE 00Z NSSL WRF ARW SHOWS A SIMILAR SCENARIO. GIVEN THE CURRENT SPC ANALYSES SHOWING INCREASING LOW-LEVEL LAPSE RATES AHEAD OF THE DEVELOPING LINE OF SHOWERS AND EFFECTIVE BULK SHEAR VALUES 45-50 KTS OVER THE MTS...CURRENTLY ABOUT 20 KTS OVER CENTRAL NC. ALSO...MUCAPE VALUES ARE AROUND 500 J/KG... MAINLY ACROSS THE SOUTH. RUC ANALYSIS SHOWS BULK SHEAR VALUES OVER CENTRAL NC INCREASING TO 50-60 KTS...WITH CAPE OF 500-1000 J/KG...MAINLY ACROSS THE WEST. THIS SUPPORTS THE POTENTIAL FOR THUNDERSTORMS TO DEVELOP ACROSS THE WESTERN HALF OF THE AREA TONIGHT...WITH AN ISOLATED STRONG TO SEVERE STORM POSSIBLE. MAIN THREAT WOULD BE DAMAGING WINDS. SHOWERS AND ISOLATED STORMS ARE ALSO POSSIBLE ALONG THE COASTAL PLAIN AHEAD OF THE MAIN LINE OF SHOWERS AND STORMS THIS EVENING. HOW QUICKLY THE SHOWERS AND CLOUDS MOVE OUT OF THE AREA WILL IMPACT THE LOW TEMPS FOR TONIGHT...BUT GENERALLY LOOKING AT NEAR 50 DEGREES NW TO LOW 60S SE. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... AS OF 240 PM THURSDAY... FRIDAY... LARGE UPPER LOW OVER THE UPPER MIDWEST WILL MIGRATE EAST OVER THE GREAT LAKES ON FRIDAY. THE COLD FRONT TO SLOWLY CROSS CENTRAL NC TONIGHT IS FORECAST TO MOVE FROM ROUGHLY US HWY 1 AT 12Z TO WELL EAST OF I-95 BY 18Z. EARLY IN THE DAY...FORCING FOR ACCENT WILL MAINLY BE LIMITED TO UPPER DIVERGENCE IN THE RIGHT ENTRANCE OF THE DEPARTING 120KT UPPER JET...WITH ONLY 30M HEIGHT FALLS AND INCREASINGLY STABLE AND DRY AIR ALOFT. ANY REDEVELOPMENT OF SHOWERS DURING THE FIRST HALF OF THE DAY WILL BE TIED TO WEAK FRONTAL CONVERGENCE OVER THE COASTAL PLAIN...BUT EVEN THAT IS FORECAST TO WEAKEN AS THE FLOW BECOMES MORE UNIDIRECTIONAL AND SOUTHWESTERLY. WITH CLEARING SKIES AND A MODEST HEIGHT GRADIENT BEHIND THE FRONT...FORECAST SOUNDINGS SHOW BOUNDARY LAYER MIXING...GREATEST IN THE WEST...LEADING TO SOUTHWESTERLY WIND GUSTS OF UP TO 20-25KT DURING THE AFTERNOON. A LOW LEVEL TRAJECTORY OUT OF THE SOUTHWEST BEHIND THE FRONT WILL NOT LEAD TO A LARGE COOL DOWN BASED ON THE UPSTREAM AIRMASS...WITH MOST GUIDANCE SHOWING HIGHS OF 70-78 NORTHWEST TO SOUTHEAST. FRIDAY NIGHT... OTHER THAN THE POTENTIAL FOR MID CLOUDS PASSING THROUGH THE BASE OF THE UPPER LEVEL LOW...WHICH WILL BEGIN TO OPEN UP BY SATURDAY MORNING...SKIES SHOULD BE MOSTLY CLEAR. AGAIN THERE IS NO REAL STRONG COLD ADVECTION SATURDAY NIGHT AND LOWS SHOULD SETTLE JUST BELOW NORMAL INTO THE MID TO UPPER 40S FOR MOST AREAS. SATURDAY THROUGH SUNDAY...... THE MEAN TROUGH AXIS IS FORECAST TO CROSS THE APPALACHIANS AS THE UPPER LOW OPENS AND LIFTS NORTHEASTWARD ON SATURDAY. THE COMBINATION OF UPSTREAM MOISTURE AND THE COLDEST AIR ALOFT PASSING OVERHEAD SHOULD LEAD TO ENHANCED STRATOCU IN THE LEE OF THE MOUNTAINS DURING THE AFTERNOON. 1000-850MB THICKNESSES HOVER IN THE 1360S DURING THE DAY WITH A WEAK DOWNSLOPE FLOW POTENTIALLY OFFSETTING WEAK COLD ADVECTION. THUS...WILL KEEP HIGHS WITHIN A COUPLE DEGREES OF THOSE BASED ON THICKNESSES...66-73 NORTHWEST TO SOUTHEAST. LOWS SATURDAY NIGHT IN THE LOW TO MID 40S UNDER MOSTLY CLEAR SKIES...ALTHOUGH FORECAST SOUNDINGS SUGGEST CONDITIONS COULD BE FAVORABLE FOR SOME OROGRAPHIC CIRRUS. HIGH PRESSURE WILL BEGIN TO BUILD INTO THE AREA FROM THE SOUTHWEST SUNDAY WITH MOSTLY SUNNY SKIES AND HIGHS AROUND 70S. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 250 PM THURSDAY... OVERALL...THIS PERIOD WILL BE DOMINATED BY HIGH PRESSURE BOTH AT THE SURFACE AND ALOFT. SURFACE HIGH PRESSURE WILL SETTLE RIGHT OVER THE REGION...WHILE A MID LEVEL RIDGE WILL BUILD IN FROM THE GULF COAST AREA. THIS WILL RESULT IN A PROLONGED PERIOD OF DRY CONDITIONS. AS HEIGHTS GRADUALLY INCREASE THROUGHOUT THE PERIOD...TEMPS WILL SLOWLY MODERATE...WITH HIGHS TRENDING TO ABOVE NORMAL. HOWEVER...WITH FAIRLY DRY AIR IN PLACE AND MOSTLY CLEAR SKIES...OUR DIURNAL RANGE SHOULD BE LARGE...WITH OVERNIGHT LOWS ABLE TO DROP OFF INTO THE 40S. A BACK DOOR FRONT MAY APPROACH THE REGION LATE IN THE PERIOD...BUT AS OF NOW MODELS SHOW LITTLE IMPACT TO THE AREA. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 200 PM THURSDAY... 24 HOUR TAF PERIOD: CHALLENGING TAF FORECAST WITH REGARD TO TIMING OF PRECIP AHEAD OF A COLD FRONT MOVING IN FROM THE WEST OVERNIGHT AND INTO FRIDAY. BEST CHANCE OF RAIN BEGINNING AROUND 00Z AT KINT AND KGSO...AND CLOSER TO 03Z-05Z ELSEWHERE. STILL QUITE A BIT OF UNCERTAINTY WITH REGARD TO COVERAGE AND INTENSITY OF PRECIP AS WELL. VISBYS COULD GO DOWN TO MVFR/IFR WHERE PRECIP IS OCCURRING...AND MVFR/IFR CIGS AND VISBYS WITH FOG/STRATUS CONDITIONS BEGINNING AFTERWARD. CEILINGS HAVE ALREADY GONE TO MVFR AT KINT AND KGSO AND ASIDE FROM SOME BRIEF SCATTERING...WILL LIKELY REMAIN MVFR THE REMAINDER OF THE AFTERNOON. CEILINGS AT THE REMAINING TERMINALS SHOULD REMAIN LOW END VFR... POTENTIALLY DROPPING TO HIGH END MVFR BEFORE MIDNIGHT. WINDS ARE EXPECTED TO BE GUSTY AT ALL TERMINALS THIS AFTERNOON...MAINLY OUT OF THE SOUTH. CIG AND VISBY RESTRICTIONS SHOULD START CLEARING UP AFTER SUNRISE FRIDAY AS DRIER AIR MOVES IN BEHIND THE FRONT. FRIDAY NIGHT THROUGH TUESDAY: WITH THE EXCEPTION OF SOME LINGERING SHOWERS ALONG THE COASTAL PLAIN FRIDAY AFTERNOON...THE PRECIP AND OVERCAST SKIES SHOULD BE OUT OF CENTRAL NC BY 15Z AND 21Z FRIDAY...RESPECTIVELY AS THE COLD FRONT PUSHES THROUGH THE AREA. WINDS WILL BE GUSTY BEHIND THE FRONT... POTENTIALLY 20 KTS OR MORE AT TIMES. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT AND LINGER THROUGH TUESDAY...RESULTING IN VFR CONDITIONS FOR THE REMAINDER OF THE PERIOD. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...KC SHORT TERM...BLS LONG TERM...KRR AVIATION...KC
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
903 PM CDT FRI OCT 19 2012 .UPDATE... CURRENT FORECAST HAS THE OVERALL PATTERN WELL IN HAND THIS EVENING. CLASSIC PROBLEM EXISTS WITHIN THE REGION AS A BAND OF LOW LEVEL MOISTURE IS TRAPPED BETWEEN SYSTEMS. THE LOW CLOUDS...AS SEEN IN THE 11-3.9 IR AND METARS...ARE REFLECTED RELATIVELY WELL BY THE 6C AND LESS SURFACE DEW-POINT DEPRESSION. USING THE RAP AND NAM12 SURFACE TD DEPRESSION AND 950-900MB LAPSE RATES AS A GUIDE WILL SLOW CLEARING DOWN. PREVIOUS FCST HAS PATCHY BR WHICH IS ALREADY SHOWING UP IN SOME OF THE METARS...WITH BOUNDARY MOISTURE CAPPED BY VERY DRY AIR SUSPECT FOG WILL CONTINUE AS FORECAST. WILL BACK UP PATCHY FOR TO CURRENT TIME IN UPDATE. OTHERWISE WILL TOUCH UP THE WINDS AND TEMPS ACCORDINGLY...BUT THESE TWEAKS ARE VERY MINOR. && .AVIATION... QUITE THE MIX OF CIG/VSBY THIS EVENING. FAIRLY WIDESPREAD MVFR/IFR CEILINGS AND VSBY EXPECTED TO CONTINUE THROUGH THE NIGHT. BRIEF LIFR CIG ALSO POSSIBLE. FOG LOOP ALSO SHOWS A FEW NORTH-SOUTH ORIENTED HOLES/THIN SPOTS ON THE MINNESOTA SIDE WITH VFR CIGS AS WAS NOTED AT TVF AND BJI. EXPECT THESE THIN SPOTS TO CLOSE UP AS BOUNDARY LAYER COOLS AND WINDS REMAIN LIGHT AS HIGH DRIFTS OVER CWFA. THINK DVL FCST TO LOOSE LOWER CLOUDS FIRST AS MIXING INCREASES ON LEADING EDGE OF WARMER AIR ALREADY PUSHING INTO WESTERN DAKOTAS AND SASKATCHEWAN. OTRW MVFR/IFR CIGS FCST TO DOMINATE THROUGH 12Z WITH GENERALLY L/V WINDS. && .PREV DISCUSSION... /ISSUED 252 PM CDT FRI OCT 19 2012/ SHORT TERM... MAIN ISSUES EARLY ON WILL BE WHAT HAPPENS WITH THE THICK LOW CLOUDS OVER THE FA AND WHETHER ANY FOG DEVELOPS TONIGHT. OTHERWISE THERE ARE STILL SOME WEAK WAVES IN THE SOUTHWEST FLOW WHICH MAY GENERATE SOME LIGHT PCPN AT TIMES...BUT NOTHING MAJOR. TONIGHT...LIKE MENTIONED THERE IS QUITE A BIT OF THICK CLOUD COVER ACROSS THE FA NOW. REGIONAL RADARS SHOW THE THIN BAND OF PCPN TO THE EAST OF THE RED RIVER VALLEY SHRINKING IN COVERAGE WITH A FEW BREAKS IN THE CLOUDS JUST TO THE EAST OF THE FA. TEMPS HAVE STAYED PRETTY CHILLY TODAY AND WITH THE RAIN THE TEMP/DEW POINT SPREADS ARE PRETTY CLOSE. THERE ARE SOME BREAKS IN THE CLOUDS ALSO MOVING TOWARD CENTRAL ND BUT THERE ARE ALSO SOME HIGHER LEVEL CLOUDS STREAMING IN OVERHEAD. THIS IS ONE OF THOSE SCENARIOS WHERE IT LOOKS LIKE SOME CLEARING MAY OCCUR BY LATE AFTERNOON BUT ONCE THE SUN GOES DOWN THE CLOUDS STAY PUT OR BACK UP. THEREFORE WILL GO WITH A FAIRLY CLOUDY IDEA FOR TONIGHT WHICH WILL PROBABLY KEEP THE TEMP/DEW POINT SPREADS PRETTY CLOSE AND COULD RESULT IN SOME FOG. NOT SURE HOW LOCALIZED OR WIDESPREAD IT MAY BE AT THIS POINT SO WILL START WITH PATCHY FOG FOR NOW. THE CLOUDS WILL ALSO PREVENT TEMPS FROM FALLING MUCH TONIGHT. SAT-MON...A FEW DAYS AGO SAT WAS LOOKING LIKE A NICE DAY. NOW A LOT OF HOW THE DAY TURNS OUT HINGES ON WHAT HAPPENS WITH THE CLOUDS TONIGHT. IF THEY STAY PUT IT COULD BE ANOTHER CLOUDY DAY SAT WITH COOLER TEMPS RESULTING FROM THE LESSER AMOUNT OF SUN. UPPER JET NOSES IN SAT NIGHT/SUNDAY AND COULD PROVIDE SOME SPRINKLES OR LIGHT SHOWERS ACROSS THE NORTHWEST THRU NORTHERN FA. THEREFORE THERE COULD BE A DECENT AMOUNT OF CLOUDS AROUND ON SUNDAY TOO WHICH WOULD HOLD DOWN MAX TEMPS THEN TOO. HAD TO DROP SUNDAY HIGHS FROM WHAT WE WERE EXPECTING YESTERDAY TOO. NEXT LITTLE WAVE IN THE SOUTHWEST FLOW MAY SPREAD MORE LIGHT PCPN INTO THE WESTERN FA MON AFTERNOON. LONG TERM (MON NIGHT-FRI)... WHILE THE LONG TERM LOOKS WET...MODELS IN A LOT OF DISAGREEMENT WITH TIMING OF A WAVE MOVING ACROSS AREA AND LIFTING A SWATH OF RAIN OUT OF THE CNTRL ROCKIES UP THROUGH THE DAKOTAS. ECMWF ROUGHLY 24 HRS FASTER ON TIMING OF MAIN BAND OF SHOWERS. CERTAINLY LOOKS LIKE THE MIDDLE OF THE WORK WEEK WILL SEE SOME RAIN HOWEVER. END OF THE LONG TERM MAY SEE A BREAK DUE WITH MODELS BOTH SHOWING A DRY SLOT WED NIGHT. GFS THEN KEEPS SOME WRAP AROUND MOISTURE ACROSS THE NORTH. OVERNIGHT LOWS WED NIGHT AND THU NIGHT MAY APPROACH THE FREEZING MARK...AND SOME OVERNIGHT SNOW IS POSSIBLE AS WELL. WILL BE INTERESTING TO SEE HOW THIS SYSTEM EVOLVES IF AND WHEN MODELS COME INTO BETTER AGREEMENT. AVIATION... MOSTLY MVFR AND IFR CONDS THIS EVENING AS RAIN SHOWERS DEPART THE AREA. CLOUDS ARE BEGINNING TO THIN...HOWEVER STILL MAINLY OVC ACROSS THE TAF SITES. ARE SEEING CLOUDS TO THE EAST BECOME MORE CUMULIFORM...AND WILL NEED TO WATCH FOR ANY CLEARING AS ATMS IS PRIMED FOR FOG IF WINDS BECOME CALM IN ANY CLEAR SPOTS TONIGHT. CONFIDENCE THAT THE CLOUD COVER WILL CONTINUE TO THIN AND EVENTUALLY CLEAR OUT IS LOW...HOWEVER...THUS NO MENTION OF FOG IN 18Z TAFS. WILL SEE CIGS LIFT OUT OF IFR RANGE BY MORNING. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ EWENS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1012 PM EDT FRI OCT 19 2012 .SYNOPSIS... A DEEP CLOSED UPPER LOW LOCATED OVER MICHIGAN THIS EVENING WILL MOVE SLOWLY TOWARD THE LOWER LAKES OVERNIGHT...BEFORE HEADING DOWN THE ST LAWRENCE RIVER VALLEY SATURDAY. HIGH PRESSURE WILL BUILD NORTHEAST FROM THE TENNESSEE VALLEY SUNDAY INTO MONDAY WITH FAIR AND MILDER CONDITIONS. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... SHOWERS AND THUNDERSTORMS HAVE FINALLY CLEARED THE EASTERN ZONES. MEANWHILE TO THE WEST...DEEPER MOISTURE ASSOCIATED WITH THE UPPER LOW HAS A FEW SHOWERS...AN EVEN SOME LIGHTNING STRIKES MOVING THRU THE LAURELS UP INTO THE CENTRAL MOUNTAINS. NEITHER THE RAP NOR THE HRRR SEE THESE SHOWERS SO NO REAL MODEL HELP IN TRYING TO TIME THEM IN OR OUT...BUT EXTRAPOLATION BRINGS THEM INTO NRN PA OVER THE NEXT FEW HOURS...LEAVING MUCH OF THE REMAINDER OF THE OVERNIGHT DRY IN MOST AREAS. LOWS TONIGHT WILL GENERALLY BE IN THE 40S...WITH SOME UPPER 30S POSSIBLE IN NORMAL NRN COLD SPOTS. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... AS THE SLOWLY FILLING UPPER LOW AND SOUTHWARD TRAILING THERMAL TROUGH LIFTS INTO SRN ONTARIO THROUGH SATURDAY...IT WILL HAVE A GLANCING BLOW ON THE ERN HALF OF THE STATE...WITH THE MAIN EFFECT BEING AN INCREASE IN STRATO CU SATURDAY MORNING ACROSS THE CENTRAL MTNS /AND ACROSS THE SUSQ VALLEY DURING THE MIDDAY AND AFTERNOON HOURS. ISOLATED SHOWERS WILL DEVELOP DURING THE AFTERNOON ACROSS THE CENTRAL RIDGE AND VALLEY REGION...WHILE THE MORE NUMEROUS SHOWERS WILL STAY CONFINED ACROSS THE WESTERN HIGH TERRAIN AND BENEATH THE MID-LEVEL COLD POOL. THE LATEST SREF AND GEFS MEAN QPF IS STILL AOB 0.10 OF AN INCH THOUGH. MAX TEMPS IN THE U40S ACROSS THE WESTERN MTNS...AND MID 50S TO MID 60S AS WE HEAD SE ACROSS THE CENTRAL MTNS AND INTO THE LOWER SUSQ VALLEY. THESE WILL BE SEVERAL DEG F BELOW NORMAL. WARMING TEMPS ALOFT AND HIGH PRESSURE BUILDING IN FROM THE SW WILL LEAD TO CLEARING SKIES AND DIMINISHING SOUTHWEST WIND AND CHILLY NIGHT TIME TEMPS IN THE 30S TO LOWER 40S. && .LONG TERM /SUNDAY THROUGH FRIDAY/... AS IS COMMON IN LATE OCTOBER...EXTENDED GUIDANCE HAS LARGE MODEL SPREAD. IN GENERAL...WENT WITH RIDGING AND SURFACE HI PRESSURE ON SUN/MON WITH DRY WEATHER. WEAK MOISTURE SURGE ARRIVES LATE MONDAY BRINGING AN INCREASE IN CLOUDS AND SOME LOW POPS. BEHIND THIS IN THE WED-THU TIME FRAME MILD AIR IN PLACE AND WILL KEEP A SLGT CHC SHOWERS IN THE FORECAST. HIGH UNCERTAINTY LATE IN THE WEEK INTO THE WEEKEND AS LATEST GEFS SHOWS COLD PAC NW TROF MOVING INTO THE PLAINS AND HEADING EAST. AT THIS POINT LOOKS LIKE SIG COLD AIR WILL STAY WEST THRU THE EXTENDED. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... FRONTAL BOUNDARY PERSISTS OVER EASTERN PENNSYLVANIA THIS EVENING...WITH AN ACTIVE AREA OF SHRA AND A FEW TSRA ALONG IT. RADAR LOOP SHOWS CONVECTION FROM BALTIMORE TO HARRISBURG AND LANCASTER...NORTH INTO SCHUYLKILL COUNTY. AS LINGERING INSTABILITY BEGINS TO WANE AFTER SUNSET...EXPECT ACTIVITY TO LESSEN IN INTENSITY DURING THE EVENING. STILL...BOUNDARY WILL ACT TO SUPPORT AT LEAST SCATTERED SHOWER ACTIVITY FOR SEVERAL MORE HOURS. ELSEWHERE...CENTRAL AREAS SEEING SCATTERED TO BROKEN MID LEVEL DECK AROUND 7KFT. FOG BEGINNING TO DEVELOP IN AREAS WHERE SKIES ARE GENERALLY CLEAR...AND HAVE INCLUDED ADDITIONAL FOG FORMATION IN TAF LOCATIONS OVERNIGHT...WITH WIDESPREAD MVFR CONDITIONS DEVELOPING OVERNIGHT. FARTHER WEST IN KBFD AND KJST AM ANTICIPATING SOME LOWER STRATUS FORMATION AND POSSIBLE SHOWERS...SOMEWHAT LIMITING FOG FORMATION. HOWEVER...IN THESE AREAS CIGS WILL LOWER TO MVFR LEVELS. STACKED LOW OVER LAKE MICHIGAN WILL CONTINUE TO ROTATE SLOWLY NORTHEASTWARD INTO SRN ONTARIO TONIGHT AND SATURDAY. THIS SYSTEM SHOULD BRING ANOTHER ROUND OF SHOWERS TO MAINLY THE WRN MTNS SATURDAY...BEFORE LIFTING NORTHEAST ACROSS SOUTHEASTERN CANADA ON SUNDAY. HIGH PRESSURE WILL BUILD INTO THE REGION ON SUNDAY AND DOMINATE THE WEATHER PATTERN INTO EARLY NEXT WEEK. OUTLOOK... SAT...MVFR...TO BRIEFLY IFR CIGS WEST...VFR TRANSITIONING TO PERIOD OF MVFR EAST AFTER 16Z. SCT TO NUMEROUS SHRA ACROSS THE WRN PENN MTNS. SUN...MVFR WEST BCMG VFR. VFR CENTRAL/EAST. NO SIG WX. MON...VFR. NO SIG WX. TUE AND WED...VFR WITH MVFR POSS IN SCTD SHOWERS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LA CORTE/LAMBERT NEAR TERM...LA CORTE/LAMBERT SHORT TERM...LAMBERT LONG TERM...ROSS AVIATION...JUNG/LAMBERT
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
746 AM EDT THU OCT 18 2012 .SYNOPSIS... A DEEP CLOSED LOW ALOFT IN THE UPPER MISSISSIPPI VALLEY WILL MOVE SLOWLY EASTWARD ACROSS THE GREAT LAKES REGION...CONTINUING TO INFLUENCE THE WEATHER PATTERN IN PENNSYLVANIA THROUGH THE FIRST PART OF THE WEEKEND. THE MATURE SURFACE CYCLONE ASSOCIATED WITH THIS SYSTEM WILL OCCLUDE OVER THE UPPER MIDWEST AND BECOME VERTICALLY STACKED. A COLD FRONT WILL SHIFT THROUGH THE UPPER OHIO VALLEY BY LATE MORNING AND CONTINUE TO PUSH EASTWARD ACROSS THE APPALACHIANS THROUGH TONIGHT. THE UPPER LEVEL SYSTEM WILL LIFT AWAY FROM THE REGION ON SUNDAY...REPLACED BY HIGH PRESSURE WHICH WILL BRING IMPROVING CONDITIONS AND WARMER TEMPERATURES INTO NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... RECENT IR SATL TRENDS CONTINUE TO INDICATE EXPANSION OF LOW STRATUS DECK OVER THE CENTRAL RIDGE AND VALLEY REGION. HAVE INCREASED GRIDDED CLOUD COVER IN THIS AREA THRU MID MORNING. LYRD MID AND HIGH CLOUDS WILL BEGIN TO OVERSPREAD WRN PA THRU 12Z AHEAD OF APPROACHING COLD FRONT...WHICH JUST PASSED KIND AS OF 09Z. STRONG UPPER JET AND EMBEDDED SHORTWAVE TROF ROUNDING BASE OF DEEP CLOSED LOW OVER THE UPPER MIDWEST WILL DRIVE THE COLD FRONT EWD THRU THE UPPER OH VLY AND ACRS THE APPALACHIANS THRU TONIGHT. THE MAIN FCST CONCERNS IN THE NEAR TERM WILL BE TIMING OF FRONTAL RAINS AND POTENTIAL SVR WX/DMGG WIND THREAT ASSOC WITH NARROW LOW-TOPPED CONVECTIVE LINE. THE LATEST HRRR WEAKENS THE ONGOING CONVECTIVE FRONTAL BAND MOVG EWD THRU THE MID OH/TN VLY. MDL DATA INDICATES NEWD MSTR RETURN AHEAD OF THE APPROACHING FRONTAL BAND WILL BE PINCHED- OFF...RESULTING IN LIMITED INSTABILITY/CAPE OVER CENTRAL PA. THAT SAID...MARGINAL DIURNAL HEATING COMBINED WITH STRONG UPPER LEVEL DIVERGENCE - IN THE LEFT EXIT REGION OF 100+KT JET MAX - MAY BE SUFFICIENT TO SUPPORT AN INCREASE IN INTENSITY OF THIN CONVECTIVE LINE ALONG/AHEAD OF THE COLD FRONT AS IT MOVES INTO WRN PA THIS AFTN. SPC HAS MODIFIED/DECREASED THEIR SLIGHT RISK AREA TO ONLY INCLUDE ONLY SW PA...LAUREL HIGHLANDS AND THE S-CENTRAL MTNS. THEY ADMIT THAT THE SET-UP IS BORDERLINE FOR SLGT RISK AND CONFIDENCE IS LOW...HOWEVER MESO MDLS SEEM TO SUGGEST THAT THE DYNAMIC FORCING MAY OVERCOME THE LACK OF INSTABILITY/MOISTURE TO PRODUCE A NARROW LOW-TOPPED SQUALL LINE FEATURE. THESE CONVECTIVELY ENHANCED SYSTEMS USUALLY HAVE THE CAPABILITY TO PRODUCE WIND DAMAGE WITH LITTLE NO CG LIGHTNING. DAYSHIFT WILL NEED TO MONITOR THE SITUATION AS IT EVOLVES. CVRG/INTENSITY OF SHOWERS SHOULD STRENGTHEN THIS EVE AND EARLY TONIGHT AS THE FRONTAL BAND CROSSES THE CENTRAL AND ERN PRTNS OF THE CWA. A WAVE SHOULD DEVELOP AND RIDE NWD ALONG THE N-S FRONTAL ZONE...ENHANCING MSTR CONVERGENCE IN AN AXIS OF ABV NORMAL PWATS EXTENDING NWD FROM THE WRN ATLC. MODELS ARE IN PRETTY GOOD AGREEMENT IN EMPHASIZING A LCL MAX OVER EAST-CENTRAL PA TONIGHT. DAY 1 AREAL QPF AVGS BTWN 0.25-0.50" IN THE WEST AND 0.50-0.75" IN THE CENTRAL AND ERN BASINS. WOULD NOT BE SURPRISED TO SEE SOME ISOLD 1+ INCH PT AMTS. THE FCST BEST-TIMING FOR PCPN...GIVE OR TAKE...IS MID-LATE AFTN OVR WRN PA...EARLY-MID EVE IN THE CENTRAL MTNS AND LATER TNT THRU THE PREDAWN HOURS FRI ACRS THE ERN 1/3 OF THE CWA. DRY SLOT WRAPPING AROUND THE VERTICALLY STACKED SYSTEM SHOULD BRING AND END PCPN ACRS THE WRN MTNS BY LATE TNT...BUT THE FRONTAL ZONE WILL SLOW ITS EWD PROGRESSION AS IT APPROACHES THE MID-ATLC COAST DUE TO STRONG DOWNSTREAM UPPER RIDGE BUILDING OVR THE NRN ATLC. THIS SHOULD KEEP FRONTAL RAINS GOING THRU THE END OF THE PERIOD ACRS THE FAR ERN SXNS OF THE CWA...POSSIBLY CONTINUING INTO EARLY FRIDAY. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... THE BACK EDGE OF THE N-S PCPN AXIS WILL SHIFT ENEWD INTO SRN NEW ENGLAND EARLY FRIDAY. THE VERTICALLY STACKED LOW SHOULD REACH THE LAKE ERIE VCNTY BY 12Z SAT. EXPECT SOME SHOWERS AHEAD OF THE UPPER TROF AXIS MOVG THRU THE UPPER OH VLY...AS COOLER AIR ALOFT BEGINS TO FILTER INTO THE AREA. THERE SHOULD BE A DRY PERIOD IN BETWEEN THE DEPARTING FRONTAL BOUNDARY AND APPROACHING CLOSED H5 SYSTEM. FCST TEMPS ARE ACTUALLY ABV NORMAL ON FRI AS LLVL FLOW REMAINS FROM THE SOUTH. ALTHOUGH CONSENSUS IS FOR PCPN TO LIFT OUT BY FRI NGT...SECONDARY HEIGHT FALL CENTER ASSOC WITH ANOTHER S/W PIVOTING AROUND THE UPPER LOW AND NEARBY JET-ENTRANCE REGION MAY LEAD TO ADDNL MDT RAINS OVR ERN PA. SCT TO NMRS SHOWERS ARE EXPECTED INTO SAT NGT AS THE UPPER TROUGH AND COOL POOL ALOFT MOVES OVERHEAD. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF...WHICH IS THE SLOWEST OF ALL THE DETERMINISTIC MODELS TO LIFT THE SYSTEM NWD AWAY FROM THE AREA. THIS THEME CONTINUES INTO THE SECOND HALF OF THE WEEKEND...WITH THE ECMWF SHOWING A MORE PESSIMISTIC OUTCOME. ENS DATA SUGGESTS A SOLN SOMEWHERE IN BTWN THE SLOWER EC AND FASTER GFS FOR SUNDAY. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... HEIGHTS SHOULD BE ON THE RISE BY EARLY NEXT WEEK...IN RESPONSE TO TROUGHING IN THE PAC NW AND EXTENDING SWD ALONG THE WEST COAST. HIGH PRES AT THE SFC SHOULD PROVIDE FAIR AND DRY WEATHER ON MONDAY. BROAD SWLY RETURN FLOW SHOULD BOOST TEMPS ABV LATE OCT CLIMO VALUES INTO MID-WEEK. AS THE HIGH SINKS SWD INTO THE SE STATES...AN ELONGATED FRONTAL ZONE MAY DROP FAR ENOUGH SOUTH TO BRING SOME OPPORTUNITIES FOR PCPN TUE-WED MAINLY OVER THE NRN TIER. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... LOW CLDS JUST EAST OF THE OFFICE. ADJUSTED 12Z TAFS. MAIN CHANGE WAS TO ADJUST TAFS THE LAST FEW HOURS FOR LOWER CLDS MOVING IN FROM THE SE. EXPECT THESE TO BE AND OUT OF THE EASTERN AREAS THROUGH MID TO LATE MORNING. WILL CONTINUE TO MONITOR AND ADJUST AS NEEDED. DESPITE THE LOW DEWPOINTS...SPOTS LIKE MDT AND LNS WILL SEE A BIT OF FOG DURING THE NEXT HOUR OR SO. WHILE WIND FIELDS ARE NOT AS STRONG AS THEY WERE ON SUNDAY NIGHT...STILL LOOKING AT SOME GUSTY WINDS TODAY...HAVE LLWS AT BFD...JST...AND IPT. AT BFD AND JST...NEAR BEST LLJ... WHILE IPT OFTEN GETS A GUSTY SE TO EAST WIND WITH WARM ADVECTION AND FAIRLY STRONG WIND FIELDS. SPC HAS THE AREA UNDER A SLIGHT RISK FOR STRONG TO SEVERE STORMS LATER TODAY...AS THE COLD FRONT MOVES INTO THE AREA. WILL CONTINUE TO LOOK THE SITUATION OVER. MUCH OF FRIDAY INTO THE WEEKEND WILL LIKELY BE DRY AND VFR... BUT MVFR CONDITIONS WITH A FEW SHOWERS WILL BE POSSIBLE... MAINLY ACROSS THE HIGHER ELEVATIONS LIKE JST AND BFD...AS THE UPPER LVL LOW MOVES ACROSS THE AREA. OUTLOOK... FRI...SHOWERS...MAINLY EARLY...THEN MAINLY VFR. SAT...MVFR CIGS/SHRA POSS W...VFR ELSEWHERE. SUN-MON...NO SIG WX. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
630 AM EDT THU OCT 18 2012 .SYNOPSIS... A DEEP CLOSED LOW ALOFT IN THE UPPER MISSISSIPPI VALLEY WILL MOVE SLOWLY EASTWARD ACROSS THE GREAT LAKES REGION...CONTINUING TO INFLUENCE THE WEATHER PATTERN IN PENNSYLVANIA THROUGH THE FIRST PART OF THE WEEKEND. THE MATURE SURFACE CYCLONE ASSOCIATED WITH THIS SYSTEM WILL OCCLUDE OVER THE UPPER MIDWEST AND BECOME VERTICALLY STACKED. A COLD FRONT WILL SHIFT THROUGH THE UPPER OHIO VALLEY BY LATE MORNING AND CONTINUE TO PUSH EASTWARD ACROSS THE APPALACHIANS THROUGH TONIGHT. THE UPPER LEVEL SYSTEM WILL LIFT AWAY FROM THE REGION ON SUNDAY...REPLACED BY HIGH PRESSURE WHICH WILL BRING IMPROVING CONDITIONS AND WARMER TEMPERATURES INTO NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... RECENT IR SATL TRENDS CONTINUE TO INDICATE EXPANSION OF LOW STRATUS DECK OVER THE CENTRAL RIDGE AND VALLEY REGION. HAVE INCREASED GRIDDED CLOUD COVER IN THIS AREA THRU MID MORNING. LYRD MID AND HIGH CLOUDS WILL BEGIN TO OVERSPREAD WRN PA THRU 12Z AHEAD OF APPROACHING COLD FRONT...WHICH JUST PASSED KIND AS OF 09Z. STRONG UPPER JET AND EMBEDDED SHORTWAVE TROF ROUNDING BASE OF DEEP CLOSED LOW OVER THE UPPER MIDWEST WILL DRIVE THE COLD FRONT EWD THRU THE UPPER OH VLY AND ACRS THE APPALACHIANS THRU TONIGHT. THE MAIN FCST CONCERNS IN THE NEAR TERM WILL BE TIMING OF FRONTAL RAINS AND POTENTIAL SVR WX/DMGG WIND THREAT ASSOC WITH NARROW LOW-TOPPED CONVECTIVE LINE. THE LATEST HRRR WEAKENS THE ONGOING CONVECTIVE FRONTAL BAND MOVG EWD THRU THE MID OH/TN VLY. MDL DATA INDICATES NEWD MSTR RETURN AHEAD OF THE APPROACHING FRONTAL BAND WILL BE PINCHED- OFF...RESULTING IN LIMITED INSTABILITY/CAPE OVER CENTRAL PA. THAT SAID...MARGINAL DIURNAL HEATING COMBINED WITH STRONG UPPER LEVEL DIVERGENCE - IN THE LEFT EXIT REGION OF 100+KT JET MAX - MAY BE SUFFICIENT TO SUPPORT AN INCREASE IN INTENSITY OF THIN CONVECTIVE LINE ALONG/AHEAD OF THE COLD FRONT AS IT MOVES INTO WRN PA THIS AFTN. SPC HAS MODIFIED/DECREASED THEIR SLIGHT RISK AREA TO ONLY INCLUDE ONLY SW PA...LAUREL HIGHLANDS AND THE S-CENTRAL MTNS. THEY ADMIT THAT THE SET-UP IS BORDERLINE FOR SLGT RISK AND CONFIDENCE IS LOW...HOWEVER MESO MDLS SEEM TO SUGGEST THAT THE DYNAMIC FORCING MAY OVERCOME THE LACK OF INSTABILITY/MOISTURE TO PRODUCE A NARROW LOW-TOPPED SQUALL LINE FEATURE. THESE CONVECTIVELY ENHANCED SYSTEMS USUALLY HAVE THE CAPABILITY TO PRODUCE WIND DAMAGE WITH LITTLE NO CG LIGHTNING. DAYSHIFT WILL NEED TO MONITOR THE SITUATION AS IT EVOLVES. CVRG/INTENSITY OF SHOWERS SHOULD STRENGTHEN THIS EVE AND EARLY TONIGHT AS THE FRONTAL BAND CROSSES THE CENTRAL AND ERN PRTNS OF THE CWA. A WAVE SHOULD DEVELOP AND RIDE NWD ALONG THE N-S FRONTAL ZONE...ENHANCING MSTR CONVERGENCE IN AN AXIS OF ABV NORMAL PWATS EXTENDING NWD FROM THE WRN ATLC. MODELS ARE IN PRETTY GOOD AGREEMENT IN EMPHASIZING A LCL MAX OVER EAST-CENTRAL PA TONIGHT. DAY 1 AREAL QPF AVGS BTWN 0.25-0.50" IN THE WEST AND 0.50-0.75" IN THE CENTRAL AND ERN BASINS. WOULD NOT BE SURPRISED TO SEE SOME ISOLD 1+ INCH PT AMTS. THE FCST BEST-TIMING FOR PCPN...GIVE OR TAKE...IS MID-LATE AFTN OVR WRN PA...EARLY-MID EVE IN THE CENTRAL MTNS AND LATER TNT THRU THE PREDAWN HOURS FRI ACRS THE ERN 1/3 OF THE CWA. DRY SLOT WRAPPING AROUND THE VERTICALLY STACKED SYSTEM SHOULD BRING AND END PCPN ACRS THE WRN MTNS BY LATE TNT...BUT THE FRONTAL ZONE WILL SLOW ITS EWD PROGRESSION AS IT APPROACHES THE MID-ATLC COAST DUE TO STRONG DOWNSTREAM UPPER RIDGE BUILDING OVR THE NRN ATLC. THIS SHOULD KEEP FRONTAL RAINS GOING THRU THE END OF THE PERIOD ACRS THE FAR ERN SXNS OF THE CWA...POSSIBLY CONTINUING INTO EARLY FRIDAY. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... THE BACK EDGE OF THE N-S PCPN AXIS WILL SHIFT ENEWD INTO SRN NEW ENGLAND EARLY FRIDAY. THE VERTICALLY STACKED LOW SHOULD REACH THE LAKE ERIE VCNTY BY 12Z SAT. EXPECT SOME SHOWERS AHEAD OF THE UPPER TROF AXIS MOVG THRU THE UPPER OH VLY...AS COOLER AIR ALOFT BEGINS TO FILTER INTO THE AREA. THERE SHOULD BE A DRY PERIOD IN BETWEEN THE DEPARTING FRONTAL BOUNDARY AND APPROACHING CLOSED H5 SYSTEM. FCST TEMPS ARE ACTUALLY ABV NORMAL ON FRI AS LLVL FLOW REMAINS FROM THE SOUTH. ALTHOUGH CONSENSUS IS FOR PCPN TO LIFT OUT BY FRI NGT...SECONDARY HEIGHT FALL CENTER ASSOC WITH ANOTHER S/W PIVOTING AROUND THE UPPER LOW AND NEARBY JET-ENTRANCE REGION MAY LEAD TO ADDNL MDT RAINS OVR ERN PA. SCT TO NMRS SHOWERS ARE EXPECTED INTO SAT NGT AS THE UPPER TROUGH AND COOL POOL ALOFT MOVES OVERHEAD. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF...WHICH IS THE SLOWEST OF ALL THE DETERMINISTIC MODELS TO LIFT THE SYSTEM NWD AWAY FROM THE AREA. THIS THEME CONTINUES INTO THE SECOND HALF OF THE WEEKEND...WITH THE ECMWF SHOWING A MORE PESSIMISTIC OUTCOME. ENS DATA SUGGESTS A SOLN SOMEWHERE IN BTWN THE SLOWER EC AND FASTER GFS FOR SUNDAY. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... HEIGHTS SHOULD BE ON THE RISE BY EARLY NEXT WEEK...IN RESPONSE TO TROUGHING IN THE PAC NW AND EXTENDING SWD ALONG THE WEST COAST. HIGH PRES AT THE SFC SHOULD PROVIDE FAIR AND DRY WEATHER ON MONDAY. BROAD SWLY RETURN FLOW SHOULD BOOST TEMPS ABV LATE OCT CLIMO VALUES INTO MID-WEEK. AS THE HIGH SINKS SWD INTO THE SE STATES...AN ELONGATED FRONTAL ZONE MAY DROP FAR ENOUGH SOUTH TO BRING SOME OPPORTUNITIES FOR PCPN TUE-WED MAINLY OVER THE NRN TIER. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... MAIN CHANGE WAS TO ADJUST TAFS THE LAST FEW HOURS FOR LOWER CLDS MOVING IN FROM THE SE. EXPECT THESE TO BE AND OUT OF THE EASTERN AREAS THROUGH MID TO LATE MORNING. OTHERWISE...NO OTHER MAJOR CHANGES AS OF 10Z. WILL CONTINUE TO MONITOR AND ADJUST AS NEEDED. DESPITE THE LOW DEWPOINTS...SPOTS LIKE MDT AND LNS WILL SEE A BIT OF FOG DURING THE HOURS SURROUNDING SUNRISE. WHILE WIND FIELDS ARE NOT AS STRONG AS THEY WERE ON SUNDAY NIGHT...STILL LOOKING AT SOME GUSTY WINDS TODAY...HAVE LLWS AT BFD...JST...AND IPT. AT BFD AND JST...NEAR BEST LLJ... WHILE IPT OFTEN GETS A GUSTY SE TO EAST WIND WITH WARM ADVECTION AND FAIRLY STRONG WIND FIELDS. SPC HAS THE AREA UNDER A SLIGHT RISK FOR STRONG TO SEVERE STORMS LATER TODAY...AS THE COLD FRONT MOVES INTO THE AREA. WILL CONTINUE TO LOOK THE SITUATION OVER. MUCH OF FRIDAY INTO THE WEEKEND WILL LIKELY BE DRY AND VFR... BUT MVFR CONDITIONS WITH A FEW SHOWERS WILL BE POSSIBLE... MAINLY ACROSS THE HIGHER ELEVATIONS LIKE JST AND BFD...AS THE UPPER LVL LOW MOVES ACROSS THE AREA. OUTLOOK... FRI...SHOWERS...MAINLY EARLY...THEN MAINLY VFR. SAT...MVFR CIGS/SHRA POSS W...VFR ELSEWHERE. SUN-MON...NO SIG WX. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
608 AM EDT THU OCT 18 2012 .SYNOPSIS... A DEEP CLOSED LOW ALOFT IN THE UPPER MISSISSIPPI VALLEY WILL MOVE SLOWLY EASTWARD ACROSS THE GREAT LAKES REGION...CONTINUING TO INFLUENCE THE WEATHER PATTERN IN PENNSYLVANIA THROUGH THE FIRST PART OF THE WEEKEND. THE MATURE SURFACE CYCLONE ASSOCIATED WITH THIS SYSTEM WILL OCCLUDE OVER THE UPPER MIDWEST AND BECOME VERTICALLY STACKED. A COLD FRONT WILL SHIFT THROUGH THE UPPER OHIO VALLEY BY LATE MORNING AND CONTINUE TO PUSH EASTWARD ACROSS THE APPALACHIANS THROUGH TONIGHT. THE UPPER LEVEL SYSTEM WILL LIFT AWAY FROM THE REGION ON SUNDAY...REPLACED BY HIGH PRESSURE WHICH WILL BRING IMPROVING CONDITIONS AND WARMER TEMPERATURES INTO NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... RECENT IR SATL TRENDS CONTINUE TO INDICATE EXPANSION OF LOW STRATUS DECK OVER THE CENTRAL RIDGE AND VALLEY REGION. HAVE INCREASED GRIDDED CLOUD COVER IN THIS AREA THRU MID MORNING. LYRD MID AND HIGH CLOUDS WILL BEGIN TO OVERSPREAD WRN PA THRU 12Z AHEAD OF APPROACHING COLD FRONT...WHICH JUST PASSED KIND AS OF 09Z. STRONG UPPER JET AND EMBEDDED SHORTWAVE TROF ROUNDING BASE OF DEEP CLOSED LOW OVER THE UPPER MIDWEST WILL DRIVE THE COLD FRONT EWD THRU THE UPPER OH VLY AND ACRS THE APPALACHIANS THRU TONIGHT. THE MAIN FCST CONCERNS IN THE NEAR TERM WILL BE TIMING OF FRONTAL RAINS AND POTENTIAL SVR WX/DMGG WIND THREAT ASSOC WITH NARROW LOW-TOPPED CONVECTIVE LINE. THE LATEST HRRR WEAKENS THE ONGOING CONVECTIVE FRONTAL BAND MOVG EWD THRU THE MID OH/TN VLY. MDL DATA INDICATES NEWD MSTR RETURN AHEAD OF THE APPROACHING FRONTAL BAND WILL BE PINCHED- OFF...RESULTING IN LIMITED INSTABILITY/CAPE OVER CENTRAL PA. THAT SAID...MARGINAL DIURNAL HEATING COMBINED WITH STRONG UPPER LEVEL DIVERGENCE - IN THE LEFT EXIT REGION OF 100+KT JET MAX - MAY BE SUFFICIENT TO SUPPORT AN INCREASE IN INTENSITY OF THIN CONVECTIVE LINE ALONG/AHEAD OF THE COLD FRONT AS IT MOVES INTO WRN PA THIS AFTN. SPC HAS MODIFIED/DECREASED THEIR SLIGHT RISK AREA TO ONLY INCLUDE ONLY SW PA...LAUREL HIGHLANDS AND THE S-CENTRAL MTNS. THEY ADMIT THAT THE SET-UP IS BORDERLINE FOR SLGT RISK AND CONFIDENCE IS LOW...HOWEVER MESO MDLS SEEM TO SUGGEST THAT THE DYNAMIC FORCING MAY OVERCOME THE LACK OF INSTABILITY/MOISTURE TO PRODUCE A NARROW LOW-TOPPED SQUALL LINE FEATURE. THESE CONVECTIVELY ENHANCED SYSTEMS USUALLY HAVE THE CAPABILITY TO PRODUCE WIND DAMAGE WITH LITTLE NO CG LIGHTNING. DAYSHIFT WILL NEED TO MONITOR THE SITUATION AS IT EVOLVES. CVRG/INTENSITY OF SHOWERS SHOULD STRENGTHEN THIS EVE AND EARLY TONIGHT AS THE FRONTAL BAND CROSSES THE CENTRAL AND ERN PRTNS OF THE CWA. A WAVE SHOULD DEVELOP AND RIDE NWD ALONG THE N-S FRONTAL ZONE...ENHANCING MSTR CONVERGENCE IN AN AXIS OF ABV NORMAL PWATS EXTENDING NWD FROM THE WRN ATLC. MODELS ARE IN PRETTY GOOD AGREEMENT IN EMPHASIZING A LCL MAX OVER EAST-CENTRAL PA TONIGHT. DAY 1 AREAL QPF AVGS BTWN 0.25-0.50" IN THE WEST AND 0.50-0.75" IN THE CENTRAL AND ERN BASINS. WOULD NOT BE SURPRISED TO SEE SOME ISOLD 1+ INCH PT AMTS. THE FCST BEST-TIMING FOR PCPN...GIVE OR TAKE...IS MID-LATE AFTN OVR WRN PA...EARLY-MID EVE IN THE CENTRAL MTNS AND LATER TNT THRU THE PREDAWN HOURS FRI ACRS THE ERN 1/3 OF THE CWA. DRY SLOT WRAPPING AROUND THE VERTICALLY STACKED SYSTEM SHOULD BRING AND END PCPN ACRS THE WRN MTNS BY LATE TNT...BUT THE FRONTAL ZONE WILL SLOW ITS EWD PROGRESSION AS IT APPROACHES THE MID-ATLC COAST DUE TO STRONG DOWNSTREAM UPPER RIDGE BUILDING OVR THE NRN ATLC. THIS SHOULD KEEP FRONTAL RAINS GOING THRU THE END OF THE PERIOD ACRS THE FAR ERN SXNS OF THE CWA...POSSIBLY CONTINUING INTO EARLY FRIDAY. && .SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/... THE BACK EDGE OF THE N-S PCPN AXIS WILL SHIFT ENEWD INTO SRN NEW ENGLAND EARLY FRIDAY. THE VERTICALLY STACKED LOW SHOULD REACH THE LAKE ERIE VCNTY BY 12Z SAT. EXPECT SOME SHOWERS AHEAD OF THE UPPER TROF AXIS MOVG THRU THE UPPER OH VLY...AS COOLER AIR ALOFT BEGINS TO FILTER INTO THE AREA. THERE SHOULD BE A DRY PERIOD IN BETWEEN THE DEPARTING FRONTAL BOUNDARY AND APPROACHING CLOSED H5 SYSTEM. FCST TEMPS ARE ACTUALLY ABV NORMAL ON FRI AS LLVL FLOW REMAINS FROM THE SOUTH. ALTHOUGH CONSENSUS IS FOR PCPN TO LIFT OUT BY FRI NGT...SECONDARY HEIGHT FALL CENTER ASSOC WITH ANOTHER S/W PIVOTING AROUND THE UPPER LOW AND NEARBY JET-ENTRANCE REGION MAY LEAD TO ADDNL MDT RAINS OVR ERN PA. SCT TO NMRS SHOWERS ARE EXPECTED INTO SAT NGT AS THE UPPER TROUGH AND COOL POOL ALOFT MOVES OVERHEAD. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF...WHICH IS THE SLOWEST OF ALL THE DETERMINISTIC MODELS TO LIFT THE SYSTEM NWD AWAY FROM THE AREA. THIS THEME CONTINUES INTO THE SECOND HALF OF THE WEEKEND...WITH THE ECMWF SHOWING A MORE PESSIMISTIC OUTCOME. ENS DATA SUGGESTS A SOLN SOMEWHERE IN BTWN THE SLOWER EC AND FASTER GFS FOR SUNDAY. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... HEIGHTS SHOULD BE ON THE RISE BY EARLY NEXT WEEK...IN RESPONSE TO TROUGHING IN THE PAC NW AND EXTENDING SWD ALONG THE WEST COAST. HIGH PRES AT THE SFC SHOULD PROVIDE FAIR AND DRY WEATHER ON MONDAY. BROAD SWLY RETURN FLOW SHOULD BOOST TEMPS ABV LATE OCT CLIMO VALUES INTO MID-WEEK. AS THE HIGH SINKS SWD INTO THE SE STATES...AN ELONGATED FRONTAL ZONE MAY DROP FAR ENOUGH SOUTH TO BRING SOME OPPORTUNITIES FOR PCPN TUE-WED MAINLY OVER THE NRN TIER. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... LOOKING AT MAINLY VFR CONDITIONS OVERNIGHT. SKIES WILL BE MAINLY CLEAR OVERNIGHT...WITH JUST SOME HIGH CLDS TO THE WEST. DESPITE THE LOW DEWPOINTS...SPOTS LIKE MDT AND LNS COULD SEE A BIT OF FOG DURING THE HOURS SURROUNDING SUNRISE. WHILE WIND FIELDS ARE NOT AS STRONG AS THEY WERE ON SUNDAY NIGHT...STILL LOOKING AT SOME GUSTY WINDS TODAY...HAVE LLWS AT BFD...JST...AND IPT. AT BFD AND JST...NEAR BEST LLJ... WHILE IPT OFTEN GETS A GUSTY SE TO EAST WIND WITH WARM ADVECTION AND FAIRLY STRONG WIND FIELDS. SPC HAS THE AREA UNDER A SLIGHT RISK FOR STRONG TO SEVERE STORMS LATER TODAY...AS THE COLD FRONT MOVES INTO THE AREA. WILL CONTINUE TO LOOK THE SITUATION OVER. MUCH OF FRIDAY INTO THE WEEKEND WILL LIKELY BE DRY AND VFR... BUT MVFR CONDITIONS WITH A FEW SHOWERS WILL BE POSSIBLE... MAINLY ACROSS THE HIGHER ELEVATIONS LIKE JST AND BFD...AS THE UPPER LVL LOW MOVES ACROSS THE AREA. OUTLOOK... FRI...SHOWERS...MAINLY EARLY...THEN MAINLY VFR. SAT...MVFR CIGS/SHRA POSS W...VFR ELSEWHERE. SUN-MON...NO SIG WX. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...STEINBUGL AVIATION...LA CORTE/MARTIN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
320 AM EDT THU OCT 18 2012 .SYNOPSIS... A DEEP CLOSED LOW ALOFT IN THE UPPER MISSISSIPPI VALLEY WILL MOVE SLOWLY EASTWARD ACROSS THE GREAT LAKES REGION...CONTINUING TO INFLUENCE THE WEATHER PATTERN IN PENNSYLVANIA THROUGH THE FIRST PART OF THE WEEKEND. A MATURE SURFACE CYCLONE WILL OCCLUDE OVER THE UPPER MIDWEST AND BECOME VERTICALLY STACKED UNDER THE PARENT UPPER LOW. A COLD FRONT WILL SURGE EASTWARD FROM THE OHIO VALLEY AND CROSS THE APPALACHIANS EARLY TONIGHT. THE UPPER LEVEL SYSTEM WILL LIFT AWAY FROM THE REGION ON SUNDAY...REPLACED BY HIGH PRESSURE WHICH WILL DOMINATE THE WEATHER PATTERN INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... IR SATL LOOP SHOWS BAND OF MID CLOUDS LIFTING NEWD ACRS WRN PA IN ASSOC WITH SFC WARM FRONT EXTENDING SEWD FROM SFC LOW OVR NRN WI. SKIES ARE M/CLR OVR THE ERN HALF OF THE CWA...BUT RECENT TRENDS SHOW VLY FOG AND AREA OF STRATUS EXPANDING IN MID-LWR SUSQ VLY. 5-10KT S-SE GRADIENT WINDS AND INC CLOUDS WILL KEEP STEADY TEMPS NR 50F ACRS THE WRN MTNS...WHILE BLYR DECOUPLING ALLOWS TEMPS TO DIP INTO THE LOW-MID 40S OVR ERN SXNS. STRONG UPPER JET AND EMBEDDED SHORTWAVE TROF ROUNDING BASE OF DEEP CLOSED LOW OVER THE UPPER MIDWEST WILL DRIVE A COLD FRONT EWD THRU THE MID-UPPER OH VLY AND ACRS THE APPALACHIANS EARLY TONIGHT. THE MAIN FCST CONCERNS IN THE NEAR TERM WILL BE TIMING OF FRONTAL BAND RAINS AND POTENTIAL SVR WX ASSOC WITH LOW-TOPPED/CONVECTIVELY ENHANCED LINE OF MOD SHOWERS/EMBEDDED TSTMS. THE LATEST HRRR WEAKENS THE ONGOING CONVECTIVE FRONTAL BAND MOVG EWD THRU THE LWR-MID OH/TN VLYS. MDL DATA INDICATES NEWD MSTR RETURN AHEAD OF THE APPROACHING FRONTAL BAND WILL BE PINCHED- OFF...RESULTING IN LIMITED INSTABILITY/CAPE OVER CENTRAL PA. THAT SAID...MARGINAL DIURNAL HEATING COMBINED WITH STRONG UPPER LEVEL DYNAMICS MAY BE SUFFICIENT TO SUPPORT AN INCREASE IN CVRG/INTENSITY OF CONVECTIVE LINE ALONG/AHEAD OF THE COLD FRONT AS IT MOVES INTO WRN PA THIS AFTN. SPC HAS MODIFIED THEIR SLIGHT RISK AREA TO ONLY INCLUDE ONLY SW PA...THE LAUREL HIGHLANDS AND S-CENTRAL MTNS. THEY ADMIT THAT THE SET-UP IS BORDERLINE FOR SLGT RISK AND CONFIDENCE IS LOW. WHILE THE MODELS ARE IN GENERAL AGREEMENT IN THEIR RESPECTIVE MASS FIELDS...THERE ARE STILL SOME LINGERING QPF DIFFS ESP DURING THE SECOND HALF OF THE PERIOD. INTENSITY OF SHOWERS SHOULD STRENGTHEN THIS EVE AND EARLY TONIGHT AS THE FRONTAL BAND CROSSES THE CENTRAL AND ERN PRTNS OF THE CWA. A WAVE SHOULD DEVELOP AND RIDE NWD ALONG THE N-S FRONTAL ZONE...ENHANCING MSTR CONVERGENCE IN AN AXIS OF ABV NORMAL PWATS EXTENDING NWD FROM THE WRN ATLC. DAY 1 AREAL QPF AVGS BTWN 0.25-0.50" IN THE WEST AND 0.50-0.75" IN THE CENTRAL AND ERN BASINS. WOULD NOT BE SURPRISE TO SEE SOME ISOLD 1 INCH PT AMTS. THE FCST BEST-TIMING FOR PCPN...GIVE OR TAKE...IS LATE AFTN/EARLY EVE OVR WRN PA...MID EVE-EARLY TNT IN THE CENTRAL MTNS AND LATE TNT THRU THE PREDAWN HOURS FRI ACRS THE ERN 1/3 OF THE CWA. DRY SLOT WRAPPING AROUND THE VERTICALLY STACKED SYSTEM SHOULD BRING AND END PCPN ACRS THE WRN MTNS BY LATE TNT...BUT THE FRONTAL ZONE WILL SLOW ITS EWD PROGRESSION AS IT APPROACHES THE MID-ATLC COAST DUE TO STRONG DOWNSTREAM UPPER RIDGE BUILDING OVR THE NRN ATLC. THIS SHOULD KEEP FRONTAL RAINS GOING THRU THE END OF THE PERIOD ACRS THE FAR ERN SXNS OF THE CWA. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... THE BACK EDGE OF THE N-S PCPN AXIS WILL SHIFT ENEWD INTO SRN NEW ENGLAND EARLY FRIDAY. THE VERTICALLY STACKED LOW SHOULD REACH THE LAKE ERIE VCNTY BY 12Z SAT. EXPECT SOME SHOWERS AHEAD OF THE UPPER TROF AXIS MOVG THRU THE UPPER OH VLY...AS COOLER AIR ALOFT BEGINS TO FILTER INTO THE AREA. THERE SHOULD BE A DRY PERIOD IN BETWEEN THE DEPARTING FRONTAL BOUNDARY AND APPROACHING CLOSED H5 SYSTEM. FCST TEMPS ARE ACTUALLY ABV NORMAL AS LLVL FLOW REMAINS FROM THE SOUTH. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... THE MASSIVE UPPER CYCLONE WILL CROSS THE REGION ONLY SLOWLY...BRINGING THE COLDEST AIR OVERHEAD DURING THE DAY ON SATURDAY. WE SHOULD SEE SCT/NRMS DAYTIME SHOWERS WITH THE COLD AIR/INSTABILITY ON SATURDAY. COULD EVEN BE SOME THUNDER OR SMALL HAIL...BUT JUST A TINY CHANCE OF THAT. WILL NOT MENTION YET. A MASSIVE ANTICYCLONE THEN BUILDS OVER THE SOUTHEASTERN STATES AND UP INTO THE MID-ATLANTIC. THE ROUND-ABOUT PATH FOR ANY MOISTURE WILL MAKE IT TOUGH TO CREATE CLOUDS/PRECIP FOR THE REST OF THE EXTENDED PERIOD. IN FACT...THE SW/WESTERLY FLOW WILL BE GRABBING ABNORMALLY HOT AIR FROM THE PLAINS AND OHIO VALLEY AND HANDING IT TO US. AT THE SAME TIME...THE FAST ZONAL WESTERLIES WILL BE SET UP JUST TO OUR N. A SFC BOUNDARY WILL SET UP JUST TO OUR NORTH PER THE ECMWF AND PERHAPS IN OUR NRN TIER PER GFS. THIS PATHWAY WILL BE THE CAUSE FOR A LONG PERIOD OF SLIGHT CHCS IN THE NRN TIER...WHILE THE REST OF THE AREA SHOULD BE DRY AND ABNORMALLY WARM UNDER THE BIG HIGH PRESSURE. SHOULD THE BOUNDARY SET UP FARTHER TO THE SOUTH...THE POPS WILL NEED TO CLIMB ACCORDINGLY... BUT EVEN THEN...THE MOISTURE WILL HAVE TO TRAVEL A LONG WAY TO GET HERE...AND QPFS WOULD BE LOW. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... LOOKING AT MAINLY VFR CONDITIONS OVERNIGHT. SKIES WILL BE MAINLY CLEAR OVERNIGHT...WITH JUST SOME HIGH CLDS TO THE WEST. DESPITE THE LOW DEWPOINTS...SPOTS LIKE MDT AND LNS COULD SEE A BIT OF FOG DURING THE HOURS SURROUNDING SUNRISE. WHILE WIND FIELDS ARE NOT AS STRONG AS THEY WERE ON SUNDAY NIGHT...STILL LOOKING AT SOME GUSTY WINDS TODAY...HAVE LLWS AT BFD...JST...AND IPT. AT BFD AND JST...NEAR BEST LLJ... WHILE IPT OFTEN GETS A GUSTY SE TO EAST WIND WITH WARM ADVECTION AND FAIRLY STRONG WIND FIELDS. SPC HAS THE AREA UNDER A SLIGHT RISK FOR STRONG TO SEVERE STORMS LATER TODAY...AS THE COLD FRONT MOVES INTO THE AREA. WILL CONTINUE TO LOOK THE SITUATION OVER. MUCH OF FRIDAY INTO THE WEEKEND WILL LIKELY BE DRY AND VFR... BUT MVFR CONDITIONS WITH A FEW SHOWERS WILL BE POSSIBLE... MAINLY ACROSS THE HIGHER ELEVATIONS LIKE JST AND BFD...AS THE UPPER LVL LOW MOVES ACROSS THE AREA. OUTLOOK... FRI...SHOWERS...MAINLY EARLY...THEN MAINLY VFR. SAT...MVFR CIGS/SHRA POSS W...VFR ELSEWHERE. SUN-MON...NO SIG WX. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...STEINBUGL LONG TERM...DANGELO AVIATION...LA CORTE/MARTIN
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
506 PM EDT THU OCT 18 2012 .SYNOPSIS... A DEEP LOW PRESSURE SYSTEM WILL LINGER TO OUR NORTHWEST AS A COLD FRONT MOVES OFF THE SOUTH CAROLINA COAST ON FRIDAY. DRY HIGH PRESSURE WILL THEN BUILD IN BEHIND THE FRONT OVER THE WEEKEND AND REMAIN IN PLACE WELL INTO NEXT WEEK. && .NEAR TERM /THROUGH FRIDAY/... 2100 UTC UPDATE...NO MAJOR CHANGES NEEDED TO THE FCST. SKY COVER WILL BE TWEAKED TO ACCOUNT FOR STCU DISSIPATING AND REDEVELOPING WHILE GENERALLY SHIFTING EAST. POPS WILL BE LEFT AS IS WITH LOW END CHANCES ACROSS THE FARTHER NW ZONES. RADAR RETURNS AND THE LATEST HRRR SUPPORT A LOW MENTION OVER THE NEXT FEW HRS...ESP ACROSS THE ERN MOST NC COUNTIES. THIS AFTERNOON...STRATUS OVER THE MOUNTAINS AND HIGHER UPSTATE TERRAIN SHOULD GRADUALLY MIX OUT FROM THE EDGES INWARD. SCATTERED CUMULUS WILL LIKELY FILL IN THE AREAS SHORTLY AFTER CLEARING OCCURS. SURFACE FRONT STILL ACROSS THE MID TN VALLEY NOW PRODUCING SOME LIGHT PRECIP WITH A FEW SCATTERED CONVECTIVE CELLS OVER NE TN. THIS IS VERY SIMILAR TO DEPICTION ON 15Z HRRR RUN. THE NE TN ACTIVITY AFFECTS MAINLY THE NRN PORTION OF THE CWA IN THAT DEPICTION WHILE THE LIGHTER MORE STRATIFORM ACTIVITY DOES NOT MAKE IT ACROSS THE MOUNTAINS. THIS SUPPORTS EARLIER DECISION TO KEEP CHANCE POPS IN THE NRN CWA NEAR THE SUPPORT FROM THE UPPER TROUGH. IN THE FAR EASTERN CWA WHERE SKIES CLEARED EARLIER AND THERE HAS BEEN MORE TIME TO DESTABILIZE...PROG SOUNDINGS SHOW 500 J OR SO OF CAPE WHICH WARRANTED A CHC MENTION THERE. DEPENDING ON HOW SOON THE STRATUS CLEAR OUT IN THE WEST AND DESTABILIZATION OCCURS...SUBSEQUENT REVISIONS MAY NEED TO BE MADE TO INCREASE POPS IN THAT AREA. FRONT SHOULD BE EAST OF THE CWA BY MID EVENING AND CLEAR SKIES SHOULD PROGRESS EASTWARD. TEMPS SHOULD BE NEAR NORMAL AS WINDS WILL KEEP THE AREA FROM EXPERIENCING PRIME RADIATIONAL COOLING AND ALSO LIKELY KEEPING FOG AT BAY. SFC DEWPOINTS SHOULD GRADUALLY DROP OVERNIGHT WHICH WILL INHIBIT FOG FORMATION AS WELL. CLEAR SKIES AND COOL AIR ALOFT WILL CAUSE DEEP MIXING ON FRIDAY. THIS WILL ALLOW STRONG WINDS TO MIX DOWN TO THE SURFACE...GENERALLY IN THE 20 TO 25 KT RANGE...BUT SOMEWHAT HIGHER OVER THE MOUNTAINS. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/... AS OF 200 PM THURSDAY...A DEEP UPPER LOW OVER THE GREAT LAKES WILL BEGIN TO SLOWLY SHIFT NORTHEAST AND REACH NORTHERN NEW ENGLAND ON SUNDAY. MODEL GUIDANCE KEEPS THE DEEPER MOISTURE ASSOCIATED WITH THE LARGE LOW TO THE NORTH OF THE AREA. HENCE...EXCEPT FOR SOME CLOUDS ACROSS THE NC MOUNTAINS FRI NIGHT...GENERALLY CLEAR CONDITIONS ARE ANTICIPATED SAT THROUGH SUN AS SURFACE HIGH PRESSURE GRADUALLY BUILDS EAST OVER THE REGION. MOS GUIDANCE IS RATHER CHILLY OVER THE MOUNTAINS FOR BOTH FRI NIGHT AND SAT NIGHT WITH GENERALLY MID 30S FOR LOWS. THERE MAY BE ENOUGH WIND/CLOUDS FRI NIGHT TO PRECLUDE WIDESPREAD FROST...BUT CONDITIONS SAT NIGHT WILL FAVOR WIDESPREAD FROST AS HIGH PRESSURE SETTLES OVER THE AREA. MAX TEMPS WILL BE NEAR CLIMO PER A MOS BLEND. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... AS OF 215 PM THURSDAY...LOOKS LIKE THE MEDIUM RANGE WILL BE QUIET WITH TEMPS ABOVE CLIMO. ALL THE MEDIUM RANGE MODELS BUILD AN UPPER RIDGE OVER THE EASTERN U.S. THE FIRST PART OF THE NEW WORK WEEK AND IT THEN HOLDS SWAY INTO THE END OF THE WEEK. A BACKDOOR COLD FRONT MAY APPROACH THU PER HPC/GFS GUIDANCE...BUT THE 00Z ECM KEEPS IT WELL NORTH OF THE FORECAST AREA. THEREFORE...EXPECT SURFACE HIGH PRESSURE TO PROVIDE MOSTLY CLEAR CONDITIONS THROUGH THE PERIOD WITH THE AFOREMENTIONED SEASONALLY WARM CONDITIONS. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... 2100 UTC UPDATE...DIDN/T SEE MUCH REASON TO KEEP TEMPO TS GOING UNTIL 23Z SO REMOVED MENTION. SOME -SHRA ARE DEVELOPING WELL EAST OF THE TERMINAL ALONG A LINE N/S. THE HRRR HAS PREDICTED THIS WELL AND WILL GO WITH A NON/THREAT TSTMS AT KCLT AS ADVERTISED BY THAT MODEL. AT KCLT...LOW VFR CU HAVE RAPIDLY BROKEN OUT NEAR THE AIRFIELD. EXPECT BASES OF THESE CU TO GRADUALLY RAISE THIS AFTERNOON. MODELS STILL NOT THAT CONSISTENT WITH CONVECTIVE CHANCES TODAY...BUT THEY ALL SEEM TO HAVE OVERDONE PRECIP THIS MORNING AROUND THE REGION. THERE IS ENOUGH INSTABILITY FORECAST BY NAM AND RUC MODELS TO WARRANT A TEMPO FOR THUNDER THOUGH CONFIDENCE IS FAIRLY LOW GIVEN THE POOR PERFORMANCE SO FAR TODAY. WINDS WILL GRADUALLY SHIFT TO THE SOUTHWEST WITH FRONTAL PASSAGE TONIGHT. ELSEWHERE...CONVECTIVE CHANCES THIS AFTERNOON WILL BE BEST ACROSS THE NORTHERN AND FAR EASTERN PORTIONS OF THE AREA...THE NORTH BEING NEARER A PASSING SHORTWAVE TROUGH AND THE EAST SEEING THE MOST INSTABILITY AHEAD OF THE APPROACHING COLD FRONT. KHKY LOOKS LIKE THE MOST LIKELY SITE TO BE AFFECTED BY PRECIP/THUNDER...BUT CONFIDENCE IS LOW ENOUGH I WILL ONLY MENTION VCTS. BEHIND THE FRONT SOME CIRRUS WILL REMAIN OVERHEAD INTO TOMORROW WITH UPPER LEVEL LOW STILL SPINNING TO OUR NORTHWEST. CLEAR ENOUGH TONIGHT THAT GOOD RADIATIONAL COOLING SHOULD OCCUR THOUGH WINDS WILL NOT BE ABLE TO CALM COMPLETELY AND WE WILL ALSO SEE MOISTURE DIMINISH AFTER THE FRONTAL PASSAGE...SO NOT ANTICIPATING ANY VSBY RESTRICTIONS DUE TO FOG TONIGHT. OUTLOOK...EXPECT VFR CONDITIONS TO CONTINUE THROUGH THE WEEKEND. THE EXCEPTION WILL BE EARLY MORNING MOUNTAIN VALLEY FOG DURING THAT TIMEFRAME. WINDS MAY GUST TO 20 KT OR MORE AT TIMES OVER THE REGION FRIDAY AFTERNOON. AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)... WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM && .FIRE WEATHER... MAXIMUM TEMPERATURES IN THE 60S ACROSS THE MTNS AND 70S FOOTHILLS AND PIEDMONT ON FRIDAY WILL COMBINE WITH DRIER DEW POINTS ACROSS THE REGION TO PUSH AFTERNOON RH VALUES DOWN INTO THE 25 TO 30 PERCENT RANGE FRI AFTN. IN ADDITION...BREEZY SW WINDS ARE EXPECTED THROUGH THE DAY WITH OCCASIONAL GUSTS IN THE 25 TO 30 KT RANGE. DEPENDING UPON HOW MUCH RAIN FALLS AHEAD OF THE FRONT PASSING THIS AFTN/EVENING...FUELS COULD BE DRY ENOUGH TO CREATE HEIGHTENED FIRE DANGER IN SOME AREAS FRI AFTN. RAIN CHANCES ARE BEST OVER THE NRN MOUNTAINS AND ERN PIEDMONT. THIS WILL NEED TO BE MONITORED CLOSELY THROUGH THU. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PAT NEAR TERM...SBK/WIMBERLEY SHORT TERM...LG LONG TERM...LG AVIATION...SBK/WIMBERLEY FIRE WEATHER...
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
243 PM EDT THU OCT 18 2012 .SYNOPSIS... A DEEP LOW PRESSURE SYSTEM WILL LINGER TO OUR NORTHWEST AS A COLD FRONT MOVES OFF THE SOUTH CAROLINA COAST ON FRIDAY. DRY HIGH PRESSURE WILL THEN BUILD IN BEHIND THE FRONT OVER THE WEEKEND AND REMAIN IN PLACE WELL INTO NEXT WEEK. && .NEAR TERM /THROUGH FRIDAY/... THIS AFTERNOON...STRATUS OVER THE MOUNTAINS AND HIGHER UPSTATE TERRAIN SHOULD GRADUALLY MIX OUT FROM THE EDGES INWARD. SCATTERED CUMULUS WILL LIKELY FILL IN THE AREAS SHORTLY AFTER CLEARING OCCURS. SURFACE FRONT STILL ACROSS THE MID TN VALLEY NOW PRODUCING SOME LIGHT PRECIP WITH A FEW SCATTERED CONVECTIVE CELLS OVER NE TN. THIS IS VERY SIMILAR TO DEPICTION ON 15Z HRRR RUN. THE NE TN ACTIVITY AFFECTS MAINLY THE NRN PORTION OF THE CWA IN THAT DEPICTION WHILE THE LIGHTER MORE STRATIFORM ACTIVITY DOES NOT MAKE IT ACROSS THE MOUNTAINS. THIS SUPPORTS EARLIER DECISION TO KEEP CHANCE POPS IN THE NRN CWA NEAR THE SUPPORT FROM THE UPPER TROUGH. IN THE FAR EASTERN CWA WHERE SKIES CLEARED EARLIER AND THERE HAS BEEN MORE TIME TO DESTABILIZE...PROG SOUNDINGS SHOW 500 J OR SO OF CAPE WHICH WARRANTED A CHC MENTION THERE. DEPENDING ON HOW SOON THE STRATUS CLEAR OUT IN THE WEST AND DESTABILIZATION OCCURS...SUBSEQUENT REVISIONS MAY NEED TO BE MADE TO INCREASE POPS IN THAT AREA. FRONT SHOULD BE EAST OF THE CWA BY MID EVENING AND CLEAR SKIES SHOULD PROGRESS EASTWARD. TEMPS SHOULD BE NEAR NORMAL AS WINDS WILL KEEP THE AREA FROM EXPERIENCING PRIME RADIATIONAL COOLING AND ALSO LIKELY KEEPING FOG AT BAY. SFC DEWPOINTS SHOULD GRADUALLY DROP OVERNIGHT WHICH WILL INHIBIT FOG FORMATION AS WELL. CLEAR SKIES AND COOL AIR ALOFT WILL CAUSE DEEP MIXING ON FRIDAY. THIS WILL ALLOW STRONG WINDS TO MIX DOWN TO THE SURFACE...GENERALLY IN THE 20 TO 25 KT RANGE...BUT SOMEWHAT HIGHER OVER THE MOUNTAINS. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/... AS OF 200 PM THURSDAY...A DEEP UPPER LOW OVER THE GREAT LAKES WILL BEGIN TO SLOWLY SHIFT NORTHEAST AND REACH NORTHERN NEW ENGLAND ON SUNDAY. MODEL GUIDANCE KEEPS THE DEEPER MOISTURE ASSOCIATED WITH THE LARGE LOW TO THE NORTH OF THE AREA. HENCE...EXCEPT FOR SOME CLOUDS ACROSS THE NC MOUNTAINS FRI NIGHT...GENERALLY CLEAR CONDITIONS ARE ANTICIPATED SAT THROUGH SUN AS SURFACE HIGH PRESSURE GRADUALLY BUILDS EAST OVER THE REGION. MOS GUIDANCE IS RATHER CHILLY OVER THE MOUNTAINS FOR BOTH FRI NIGHT AND SAT NIGHT WITH GENERALLY MID 30S FOR LOWS. THERE MAY BE ENOUGH WIND/CLOUDS FRI NIGHT TO PRECLUDE WIDESPREAD FROST...BUT CONDITIONS SAT NIGHT WILL FAVOR WIDESPREAD FROST IN THE MOUNTAINS AS HIGH PRESSURE SETTLES OVER THE AREA. MAX TEMPS WILL BE NEAR CLIMO PER A MOS BLEND. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... AS OF 215 PM THURSDAY...LOOKS LIKE THE MEDIUM RANGE WILL BE QUIET WITH TEMPS ABOVE CLIMO. ALL THE MEDIUM RANGE MODELS BUILD AN UPPER RIDGE OVER THE EASTERN U.S. THE FIRST PART OF THE NEW WORK WEEK AND IT THEN HOLDS SWAY INTO THE END OF THE WEEK. A BACKDOOR COLD FRONT MAY APPROACH THU PER HPC/GFS GUIDANCE...BUT THE 00Z ECM KEEPS IT WELL NORTH OF THE FORECAST AREA. THEREFORE...EXPECT SURFACE HIGH PRESSURE TO PROVIDE MOSTLY CLEAR CONDITIONS THROUGH THE PERIOD WITH THE AFOREMENTIONED SEASONALLY WARM CONDITIONS. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... AT KCLT...LOW VFR CU HAVE RAPIDLY BROKEN OUT NEAR THE AIRFIELD. EXPECT BASES OF THESE CU TO GRADUALLY RAISE THIS AFTERNOON. MODELS STILL NOT THAT CONSISTENT WITH CONVECTIVE CHANCES TODAY...BUT THEY ALL SEEM TO HAVE OVERDONE PRECIP THIS MORNING AROUND THE REGION. THERE IS ENOUGH INSTABILITY FORECAST BY NAM AND RUC MODELS TO WARRANT A TEMPO FOR THUNDER THOUGH CONFIDENCE IS FAIRLY LOW GIVEN THE POOR PERFORMANCE SO FAR TODAY. WINDS WILL GRADUALLY SHIFT TO THE SOUTHWEST WITH FRONTAL PASSAGE TONIGHT. ELSEWHERE...CONVECTIVE CHANCES THIS AFTERNOON WILL BE BEST ACROSS THE NORTHERN AND FAR EASTERN PORTIONS OF THE AREA...THE NORTH BEING NEARER A PASSING SHORTWAVE TROUGH AND THE EAST SEEING THE MOST INSTABILITY AHEAD OF THE APPROACHING COLD FRONT. KHKY LOOKS LIKE THE MOST LIKELY SITE TO BE AFFECTED BY PRECIP/THUNDER...BUT CONFIDENCE IS LOW ENOUGH I WILL ONLY MENTION VCTS. BEHIND THE FRONT SOME CIRRUS WILL REMAIN OVERHEAD INTO TOMORROW WITH UPPER LEVEL LOW STILL SPINNING TO OUR NORTHWEST. CLEAR ENOUGH TONIGHT THAT GOOD RADIATIONAL COOLING SHOULD OCCUR THOUGH WINDS WILL NOT BE ABLE TO CALM COMPLETELY AND WE WILL ALSO SEE MOISTURE DIMINISH AFTER THE FRONTAL PASSAGE...SO NOT ANTICIPATING ANY VSBY RESTRICTIONS DUE TO FOG TONIGHT. OUTLOOK...EXPECT VFR CONDITIONS TO CONTINUE THROUGH THE WEEKEND. THE EXCEPTION WILL BE EARLY MORNING MOUNTAIN VALLEY FOG DURING THAT TIMEFRAME. WINDS MAY GUST TO 20 KT OR MORE AT TIMES OVER THE REGION FRIDAY AFTERNOON. AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)... WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM && .FIRE WEATHER... MAXIMUM TEMPERATURES IN THE 60S ACROSS THE MTNS AND 70S FOOTHILLS AND PIEDMONT ON FRIDAY WILL COMBINE WITH DRIER DEW POINTS ACROSS THE REGION TO PUSH AFTERNOON RH VALUES DOWN INTO THE 25 TO 30 PERCENT RANGE FRI AFTN. IN ADDITION...BREEZY SW WINDS ARE EXPECTED THROUGH THE DAY WITH OCCASIONAL GUSTS IN THE 25 TO 30 KT RANGE. DEPENDING UPON HOW MUCH RAIN FALLS AHEAD OF THE FRONT PASSING THIS AFTN/EVENING...FUELS COULD BE DRY ENOUGH TO CREATE HEIGHTENED FIRE DANGER IN SOME AREAS FRI AFTN. RAIN CHANCES ARE BEST OVER THE NRN MOUNTAINS AND ERN PIEDMONT. THIS WILL NEED TO BE MONITORED CLOSELY THROUGH THU. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PAT NEAR TERM...WIMBERLEY SHORT TERM...LG LONG TERM...LG AVIATION...WIMBERLEY FIRE WEATHER...
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
140 PM EDT THU OCT 18 2012 .SYNOPSIS... A DEEP LOW PRESSURE SYSTEM WILL LINGER TO OUR NORTHWEST AS A COLD FRONT MOVES OFF THE SOUTH CAROLINA COAST ON FRIDAY. DRY HIGH PRESSURE WILL THEN BUILD IN BEHIND THE FRONT OVER THE WEEKEND AND REMAIN IN PLACE WELL INTO NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1000 AM EDT...REMOVED PRECIP CHANCES FOR THIS MORNING AS THE PREFRONTAL ACTIVITY HAS DISSIPATED. RADAR ALSO INDICATES THE FRONTAL SHOWERS OVER THE CUMBERLAND PLATEAU ARE ALSO STRUGGLING. LATEST GUIDANCE PUTS HIGHEST POPS THIS AFTERNOON ACROSS THE NORTHERN PORTION OF THE CWFA WHERE UPPER LEVEL SUPPORT FROM LIFTING SHORTWAVE WILL BE BEST. PROG SOUNDINGS /EXCEPT THOSE FROM 06Z NAM/ ARE NOT IMPRESSIVE AND MODELS HAVE GENERALLY OVERDONE THE PRECIP AROUND THE REGION THIS MORNING. WILL LOWER POPS...KEEPING ONLY A LOW CHANCE OVER THE NORTH AND ALSO OVER THE EAST WHICH HAS THE MOST POTENTIAL TO DESTABILIZE AHEAD OF THE FROPA...AND A SLIGHT CHANCE ELSEWHERE. PREVIOUS DISCUSSION...A STRONG SHORT WAVE MOVES ACROSS THE AREA TODAY AS IT SWINGS AROUND A STRENGTHENING UPPER LOW DROPPING INTO THE MID WEST. THIS WAVE PUSHES A COLD FRONT...CURRENTLY JUST WEST OF THE MS VALLEY...ACROSS THE AREA AS WELL. LATEST MESOSCALE GUIDANCE HAS SLOWED THE MOVEMENT OF THIS SYSTEM. IT ALSO WEAKENS THE PRE-FRONTAL CONVECTION AS IT MOVES INTO THE WRN CWFA. CONVECTION THEN REDEVELOPS ALONG THE FRONT ACROSS THE FOOTHILLS AND PIEDMONT FOR THE AFTERNOON AND SLIDES EASTWARD THRU THE LATE AFTERNOON. THE SYNOPTIC GUIDANCE GENERALLY AGREES WITH THIS AS WELL AS IT WEAKENS THE INITIAL PUSH OF QG FORCING...THEN REDEVELOPS IT FOR THE AFTERNOON. THEREFORE...HAVE FOLLOWED THESE TRENDS WITH THE POP FCST. THE TRICKY PART IS DETERMINING THE HOW HIGH THE ACTUAL POP VALUES WILL BE. EXPECT NUMEROUS SHOWERS AS THE CONVECTION MOVES IN...BUT DIMINISHING AS IT MOVES EAST. THEN... HOW WIDESPREAD WILL THE REDEVELOPING CONVECTION BE. HAVE GONE WITH A MDL BLEND WHICH KEEPS POP GENERALLY IN THE CHC RANGE XCPT FOR THE WRN CWFA WHERE THE CONVECTION INITIALLY MOVES IN. THE SECOND CONCERN IS SEVERE WX POTENTIAL. ALTHOUGH THERE IS STRONG SHEAR AND HELICITY WITH THE PRE-FRONTAL PRECIP...THERE IS NO INSTABILITY WITH THE STRONG INVERSION IN PLACE. BEST CHC OF SEVERE WILL BE OUTSIDE OF THE MTNS THIS AFTERNOON WITH THE CONVECTION REDEVELOPING ALONG THE FRONT. MODERATE INSTABILITY DEVELOPS AND SHEAR REMAINS STRONG...ALTHOUGH IT WILL BE UNIDIRECTIONAL IN NATURE. EXPECT DAMAGING WIND GUSTS TO BE THE MAIN SVR THREAT. THE CONVECTION WILL LINGER OVER THE I-77 CORRIDOR DURING THE EVENING THEN MOVE EAST BY MIDNIGHT. SOME OF THE GUIDANCE SUGGESTS THE SYSTEM WILL SLOW DURING THE EVENING. HOWEVER...THE STALL THE SYSTEM TO OUR EAST. SKIES CLEAR SLOWLY FROM WEST TO EAST OVERNIGHT. LOWS WILL BE NEAR NORMAL. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... AS OF 300 AM THURSDAY...A DEEP VORTEX WILL BEGIN TO FILL AND SLOWLY SHIFT EAST ACRS THE GREAT LAKES FRIDAY AND SATURDAY. MODELS IN AGREEMENT ON A STRONG DRY SLOT ROUNDING THE SOUTH SIDE OF THE VORTEX INTO THE CWFA ON FRIDAY...THEN SHIFTING EAST FRIDAY NIGHT. FCST SNDGS INDICATE VERY DRY PROFILES WITH DEEP MIXING FRI AFTN...WITH SFC DEWPTS POSSIBLY DROPPING INTO THE UPR 20S TO LWR 30S DURING PEAK MIXING. MEANWHILE...H8 TEMPS DROP TO THE 6-8 C RANGE WITHIN WSWLY FLOW. SO TEMPS ARE EXPECTED TO STRUGGLE TO GET TO UPR 60S TO LWR 70S EAST OF THE MTNS...DESPITE SUNNY SKIES AND DRY AIR. STILL...AFTN RH VALUES LIKELY TO DROP INTO THE MID TO UPR 20S...WHICH COMBINED WITH BREEZY CONDITIONS MAY ENHANCE FIRE DANGER (SEE FIRE WX SECTION BELOW). FRIDAY NIGHT AND SATURDAY...WRAP AROUND MOISTURE WILL BRUSH ALONG THE TN/NC BORDER AS THE AFOREMENTIONED VORTEX BEGINS TO MOVE EAST. FLOW EVENTUALLY SHIFTS FROM WSW TO NW BY SATURDAY MORNING. H8 TEMPS DROP TO ABOUT 2-4 C WITH THE MOISTURE AND NW UPSLOPE. SO ONLY EXPECTING A PERIOD STRATUS AND PERHAPS A FEW SPRINKLES. OTHERWISE...NO FROST/FREEZE/WINTRY CONCERNS EXPECTED. TEMPS WILL BE ONE OR TWO CATEGORIES BELOW NORMAL. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... AS OF 215 PM THURSDAY...LOOKS LIKE THE MEDIUM RANGE WILL BE QUIET WITH TEMPS ABOVE CLIMO. ALL THE MEDIUM RANGE MODELS BUILD AN UPPER RIDGE OVER THE EASTERN U.S. THE FIRST PART OF THE NEW WORK WEEK AND IT THEN HOLDS SWAY INTO THE END OF THE WEEK. A BACKDOOR COLD FRONT MAY APPROACH THU PER HPC/GFS GUIDANCE...BUT THE 00Z ECM KEEPS IT WELL NORTH OF THE FORECAST AREA. THEREFORE...EXPECT SURFACE HIGH PRESSURE TO PROVIDE MOSTLY CLEAR CONDITIONS THROUGH THE PERIOD WITH THE AFOREMENTIONED SEASONALLY WARM CONDITIONS. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AT KCLT...LOW VFR CU HAVE RAPIDLY BROKEN OUT NEAR THE AIRFIELD. EXPECT BASES OF THESE CU TO GRADUALLY RAISE THIS AFTERNOON. MODELS STILL NOT THAT CONSISTENT WITH CONVECTIVE CHANCES TODAY...BUT THEY ALL SEEM TO HAVE OVERDONE PRECIP THIS MORNING AROUND THE REGION. THERE IS ENOUGH INSTABILITY FORECAST BY NAM AND RUC MODELS TO WARRANT A TEMPO FOR THUNDER THOUGH CONFIDENCE IS FAIRLY LOW GIVEN THE POOR PERFORMANCE SO FAR TODAY. WINDS WILL GRADUALLY SHIFT TO THE SOUTHWEST WITH FRONTAL PASSAGE TONIGHT. ELSEWHERE...CONVECTIVE CHANCES THIS AFTERNOON WILL BE BEST ACROSS THE NORTHERN AND FAR EASTERN PORTIONS OF THE AREA...THE NORTH BEING NEARER A PASSING SHORTWAVE TROUGH AND THE EAST SEEING THE MOST INSTABILITY AHEAD OF THE APPROACHING COLD FRONT. KHKY LOOKS LIKE THE MOST LIKELY SITE TO BE AFFECTED BY PRECIP/THUNDER...BUT CONFIDENCE IS LOW ENOUGH I WILL ONLY MENTION VCTS. BEHIND THE FRONT SOME CIRRUS WILL REMAIN OVERHEAD INTO TOMORROW WITH UPPER LEVEL LOW STILL SPINNING TO OUR NORTHWEST. CLEAR ENOUGH TONIGHT THAT GOOD RADIATIONAL COOLING SHOULD OCCUR THOUGH WINDS WILL NOT BE ABLE TO CALM COMPLETELY AND WE WILL ALSO SEE MOISTURE DIMINISH AFTER THE FRONTAL PASSAGE...SO NOT ANTICIPATING ANY VSBY RESTRICTIONS DUE TO FOG TONIGHT. OUTLOOK...EXPECT VFR CONDITIONS TO CONTINUE THROUGH THE WEEKEND. THE EXCEPTION WILL BE EARLY MORNING MOUNTAIN VALLEY FOG DURING THAT TIMEFRAME. WINDS MAY GUST TO 20 KT OR MORE AT TIMES OVER THE REGION FRIDAY AFTERNOON. AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)... WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM && .FIRE WEATHER... MAXIMUM TEMPERATURES IN THE 60S ACROSS THE MTNS AND 70S FOOTHILLS AND PIEDMONT ON FRIDAY WILL COMBINE WITH DRIER DEW POINTS ACROSS THE REGION TO PUSH AFTERNOON RH VALUES DOWN INTO THE 25 TO 30 PERCENT RANGE FRI AFTN. IN ADDITION...BREEZY SW WINDS ARE EXPECTED THROUGH THE DAY. DEPENDING UPON HOW MUCH RAIN FALLS WITH THE FRONTAL PASSAGE THURSDAY...FUELS COULD BE DRY ENOUGH TO CREATE HEIGHTENED FIRE DANGER IN SOME AREAS FRI AFTN. THIS WILL NEED TO BE MONITORED CLOSELY THROUGH THU. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PAT NEAR TERM...RWH/WIMBERLEY SHORT TERM...ARK LONG TERM...ARK/JPT AVIATION...WIMBERLEY FIRE WEATHER...ARK
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
640 PM CDT FRI OCT 19 2012 .UPDATE...FOR AVIATION. && .AVIATION... BKN-OVC VFR CIGS ARE EXPECTED THROUGH THE NIGHT WITH DIMINISHING WSW WINDS. W WINDS WILL PICK UP NEAR 10KT SATURDAY...WITH BKN VFR CIGS GRADUALLY BECMG SCT. 13 && .PREV DISCUSSION... /ISSUED 601 PM CDT FRI OCT 19 2012/ UPDATE... CURRENT SFC OBS AND CONSENSUS SHORT RANGE MODEL GUIDANCE...INCLUDING THE LATEST HIGH RESOLUTION RAPID REFRESH...SHOWING CLDY SKIES ACROSS THE MID STATE CONTINUING THRU AT LEAST THE MID EVENING HRS...WITH SOME DECREASE IN CLOUDINESS POSSIBLE LATE EVENING AND OVERNIGHT. HRRR MOST AGGRESSIVE IN ERODING CLOUD COVERAGE AS COMPARED TO SREF AND RUC 13KM. ACCORDINGLY... HAVE UPDATED THE SUITE OF FORECAST PRODUCTS TO REFLECT CLDY SKIES THRU THE EVENING HRS...WITH PTCLDY SKIES OVERNIGHT. ALSO MADE SOME MINOR CHANGES TO CLOUD COVERAGE ON SAT FOR A TRANSITION TO PTSUNNY SKIES ACROSS THE ENTIRE MID STATE DURING THIS TIME PERIOD. 31 PREV DISCUSSION.../ISSUED 149 PM CDT FRI OCT 19 2012/ SHORT TERM...LOW LEVEL WRAP-AROUND CLOUDS CONTINUED TO SINK SOUTHWARD ACROSS THE MID STATE EARLY THIS AFTERNOON. TEMPERATURES ACROSS THE EXTREME NORTH, WHERE SKIES HAVE BEEN OVC MUCH OF THE DAY, STALLED OUT IN THE UPPER 50S TO AROUND 60, WHILE SUNNY SOUTHERN AREAS SAW TEMPS PUSH TO AROUND 70 BY 1 PM. THE LIGHT RAIN AND SPRINKLES HAVE, SO FAR, REMAINED MOSTLY NORTH OF THE BORDER (UP ACROSS KY). BELIEVE LOW LEVEL MOISTURE WILL CONTINUE TO ROTATE AROUND BASE OF GREAT LAKES AND OHIO VALLEY TROUGH THROUGH SATURDAY, PROVIDING VARIABLE CLOUDINESS ACROSS OUR NORTHERN COUNTIES. THIS WILL PRODUCE A TEMP GRADIENT MUCH LIKE TODAY`S, WITH HIGHS TOMORROW RANGING FROM THE UPPER 50S AND LOWER 60S NORTH AND PLATEAU, TO AROUND 70 OVER THE SOUTH. CLOUDS FINALLY DISSIPATE BY SATURDAY NIGHT AND AN UPPER LEVEL RIDGE BUILDS IN ACROSS THE TENNESSEE VALLEY FOR SUNDAY AND MONDAY. A WEAKENING SHORTWAVE IS FORECAST TO MOVE OUT OF THE MID- MISSISSIPPI VALLEY ACROSS THE OHIO RIVER VALLEY ON TUESDAY. HOWEVER, MAINLY JUST HIGH CLOUDS ARE EXPECTED TO SWEEP ACROSS THE MID STATE AND KEEP OUR DRY WEATHER IN PLACE. RIDGE BUILDS BACK IN AFTER WEAK SHORTWAVE PASSES TO OUR NORTHWEST ON TUESDAY AND, ASIDE FROM SOME HIGH CLOUDS STREAMING IN ON SOUTHWEST FLOW, DRY WEATHER PERSISTS AT LEAST INTO THE MIDDLE OF NEXT WEEK. LONG TERM...LATEST GFS SWEEPS A COLD FRONT ACROSS OUR AREA LATE NEXT WEEK, ALONG WITH A CHANCE FOR SHOWERS AND THUNDERSTORMS. HOWEVER, PREVIOUS ECMWF KEPT TENNESSEE VALLEY MORE UNDER THE INFLUENCE OF HIGH PRESSURE AND DRY WEATHER INTO LATE NEXT WEEK. UNLESS NEW ECMWF COMES IN WITH A MORE SOLID TREND TOWARD THE GFS, WILL PROBABLY KEEP A DRY FORECAST RUNNING THROUGH THE EXTENDED PERIOD. && .OHX WATCHES/WARNINGS/ADVISORIES...NONE. && $$
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
327 PM CDT THU OCT 18 2012 .DISCUSSION... CLOUDS ARE BEGINNING TO ERODE ACROSS SOUTHEAST TEXAS AND AM EXPECTING SKIES TO BECOME MOSTLY CLEAR THIS EVENING. DRIER AIR WILL CONTINUE TO FILTER INTO THE REGION AND OBSERVATIONS UPSTREAM SHOW SFC DEW POINTS IN THE UPPER 20S TO LOWER 30S. WITH THE VERY DRY AIR IN PLACE AND WINDS DECOUPLING...FEEL OVERNIGHT LOWS WILL FALL INTO THE UPPER 40S AND LOWER 50S NORTH...MID 50S CENTRAL AND MID 60S IMMEDIATE COAST. SURFACE HIGH PRESSURE WILL BRING MOSTLY SUNNY SKIES AND WARM DAYTIME TEMPERATURES BOTH FRIDAY AND SATURDAY. THE HIGH WILL SHIFT EAST ON SATURDAY AND ONSHORE WINDS WILL BRING HIGHER HUMIDITY LEVELS BACK TO SOUTHEAST TEXAS. AN UPPER LEVEL RIDGE AND A CORRESPONDING INCREASE IN 500 MB HEIGHTS WILL ALLOW TEMPS TO WARM SUN/MON BUT THIS WARMING WILL BE TEMPERED A BIT BY THE INCREASE IN MOISTURE AND CLOUD COVER. COULD BE SOME STREAMER SHOWERS SUNDAY AND MONDAY AS FCST SOUNDINGS SHOW SATURATION BENEATH A BUILDING CAP BUT FEEL RAIN CHANCES ARE TOO SLIM TO MENTION AT THIS TIME. NOT EXPECTING MUCH DAY TO DAY CHANGE THROUGH THE END OF NEXT WEEK AS UPPER LEVEL RIDGING IMPINGES ON SOUTH TEXAS. WITH THE HIGH 500 MB HEIGHTS AND CONTINUED ONSHORE FLOW...EXPECT UNSEASONABLY WARM TEMPERATURES FOR MOST OF NEXT WEEK. 43 && .MARINE... A TIGHT PRESSURE GRADIENT WILL HELP GENERATE WINDS TO ADVISORY LEVELS THROUGH AT LEAST THIS EVENING. THE NAM12 AND RUC DIMINISH THE WINDS TO SLIGHTLY BELOW ADVISORY LEVELS BY 06Z. WILL EXTEND THE ADVISORY INTO THE EVENING FOR THE GULF WATERS. HIGH PRESSURE WILL MOVE OVERHEAD LATER ON FRIDAY. EXPECT MODERATE ONSHORE WINDS TO DEVELOP SATURDAY AFTERNOON. WIND SPEEDS MAY REACH AT LEAST CAUTION LEVELS SATURDAY NIGHT INTO TUESDAY. 40 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 52 83 57 87 69 / 0 0 0 0 10 HOUSTON (IAH) 55 84 58 87 70 / 0 0 0 0 10 GALVESTON (GLS) 67 80 70 82 76 / 0 0 0 0 10 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR THE FOLLOWING ZONES: WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL 20 NM TO 60 NM...WATERS FROM FREEPORT TO THE MATAGORDA SHIP CHANNEL OUT 20 NM...WATERS FROM HIGH ISLAND TO FREEPORT 20 TO 60 NM...WATERS FROM HIGH ISLAND TO FREEPORT OUT 20 NM. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
254 PM CDT THU OCT 18 2012 .SHORT TERM...TONIGHT THROUGH SUNDAY 254 PM CDT THU OCT 18 2012 CLOSED LOW AND ITS INFLUENCE ON THE AREA THROUGH FRIDAY EVENING IS IMMEDIATE FORECAST CONCERN...THEN ATTENTION TURNS TO WARMING SATURDAY AND ESPECIALLY SUNDAY. LATEST LOOP OF WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW CLOSED LOW CENTERED OVER THE MN/IA/WI COMMON BORDER. RADAR MOSAIC SHOWING WIDESPREAD SHOWER ACTIVITY ACROSS THE FORECAST AREA THANKS TO INFLUENCE OF DEEP COLD/CYCLONIC FLOW OVERHEAD. TEMPERATURES SUFFERING AS WELL WITH READINGS AT 2 PM ONLY IN THE 40S. LATEST NCEP MODELS AS WELL AS THE ECMWF/GEM ALL IN VERY GOOD AGREEMENT WITH SYNOPTIC SETUP THROUGH SUNDAY. LOOK OF THE CLOSED LOW TO REMAIN ANCHORED OVER THE REGION TONIGHT...MAKING A SLOW PUSH EAST TOWARD LAKE MICHIGAN BY LATE FRIDAY AFTERNOON. BUFKIT MODEL SOUNDINGS SHOWING DEEP LAYER OF MOISTURE WITH GENERALLY WEAK LIFT OVER THE AREA TONIGHT FOR SCATTERED SHOWERS/AREAS OF DRIZZLE. WITH LIGHT WINDS AND SATURATED LOWER BOUNDARY LAYER UNDER THE LOW...ALSO EXPECTING SOME LIGHT FOG ACROSS THE AREA WITH VISIBILITY GENERALLY IN THE 3-6SM RANGE. 925-850MB LAYER TEMPERATURES COOL ONLY A COUPLE DEGREES TONIGHT. WITH CLOUD COVER/SCATTERED PRECIPITATION...LOWS TONIGHT SHOULD BOTTOM OUT IN THE UPPER 30S TO LOWER 40S. PLAN ON SCATTERED SHOWERS ONCE AGAIN FOR FRIDAY WITH COLD/DEEP CYCLONIC FLOW CONTINUING. NOT MUCH RECOVERY EXPECTED IN TEMPERATURES AS WELL WITH HIGHS TOPPING OFF IN THE UPPER 40S TO A FEW LOWER 50S. A FEW LINGERING SHOWERS WILL BE POSSIBLE ACROSS NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN FRIDAY EVENING AS LAST TROUGH ASSOCIATED WITH THE CLOSED LOW ROTATES THROUGH THAT AREA. OTHERWISE FOR THE REST OF THE OVERNIGHT HOURS MODELS PUSH THE CLOSED LOW MORE INTO THE GREAT LAKES REGION WHILE A RIDGE OF HIGH PRESSURE BUILDS IN FROM THE PLAINS. NAM 925MB RH FIELD INDICATING PERHAPS A FEW BREAKS IN THE STRATUS/STRATOCUMULUS LATER FRIDAY NIGHT. THIS IS ALSO INDICATED IN THE BUFKIT SOUNDING...BUT THEN DEVELOPS QUITE A BIT OF LOW-LEVEL STRATUS TOWARD MORNING. BELIEVE MOSTLY CLOUDY IS THE WAY TO GO AT THIS POINT IN TIME. WILL HAVE TO WATCH THIS SCENARIO CLOSELY. IF THERE IS SOME CLEARING...COULD END UP WITH QUITE A BIT OF FOG WITH COOL/MOIST LOWER BOUNDARY LAYER. CLEARING SKIES AND WARMING EXPECTED SATURDAY AS THE CLOSED LOW CONTINUES TO MOVE EAST OF THE REGION AND RIDGE OF HIGH PRESSURE BUILD OVERHEAD. HIGHS SATURDAY SHOULD RESPOND NICELY TO SUNSHINE AND 925-850MB TEMPERATURES WARMING INTO THE 5-7C RANGE. PLAN ON HIGHS PUSHING WELL INTO THE 50S. WARMING WILL CONTINUE INTO SUNDAY IN SOUTHERLY FLOW AHEAD OF A COLD FRONT MOVING INTO THE DAKOTAS/WESTERN MN. NAM INDICATING 925-850MB LAYER TEMPERATURES IN THE 14-17C RANGE. THIS SHOULD EQUATE TO HIGHS SUNDAY IN THE 60S TO PERHAPS A FEW LOWER 70S WHICH WOULD BE SOME 15-20 DEGREES ABOVE NORMAL. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY 254 PM CDT THU OCT 18 2012 LATEST GFS/ECMWF IN GOOD AGREEMENT THROUGH TUESDAY...THEN DIVERGE SOMEWHAT WEDNESDAY AND THURSDAY WITH TIMING ISSUES WITH WAVES IN SOUTHWEST FLOW ALOFT. FOR SUNDAY NIGHT THROUGH TUESDAY...CYCLOGENESIS OVER THE CENTRAL PLAINS TAKES PLACE WITH THE WAVE MOVING NORTHEAST TOWARD THE AREA. BOTH MODELS SHOWING AMPLE AMOUNT OF 850MB MOISTURE TRANSPORT OUT OF THE GULF AND INTO THE AREA AHEAD OF THE ADVANCING LOW AND WARM FRONT. ALSO...MODELS PRODUCING ABOUT 300-600J/KG OF CAPE LATER SUNDAY NIGHT INTO MONDAY FOR A GOOD CHANCE OF SHOWERS/EMBEDDED THUNDERSTORMS. FOR WEDNESDAY AND THURSDAY...MODELS DIVERGE ON AMOUNT OF CYCLOGENESIS AND TIMING OF LOW PRESSURE SYSTEMS MOVING TOWARD THE AREA WITH SOUTHWEST FLOW ALOFT. TOOK A CONSENSUS APPROACH FOR NOW WHICH YIELDS MID-RANGE POPS FOR SHOWERS/THUNDERSTORMS. WILL HOPE FOR BETTER RESOLUTION IN THE MODELS WITH SUBSEQUENT RUNS. EITHER WAY...LOOKS LIKE AN ACTIVE WEATHER WEEK SETTING UP WITH EVEN THE OUT SIDE CHANCE OF STRONG-SEVERE THUNDERSTORMS DEPENDING ON AVAILABLE CAPE/SHEAR. OTHERWISE...LOOKS LIKE TEMPERATURES WILL REMAIN SOME 15 OR SO DEGREES ABOVE NORMAL. && .AVIATION...THIS AFTERNOON THROUGH FRIDAY 1159 AM CDT THU OCT 18 2012 ENTIRE PERIOD WILL BE PROBLEMATIC WITH A MOIST SFC-500MB LOW DRIFTING SLOWLY SOUTHEAST ACROSS THE UPPER MIDWEST. WIDESPREAD STRATUS CLOUDS AND MVFR CIGS TO PREVAIL THRU FRI. WITH DIURNAL COOLING AND THE CENTER OF THE SFC-MID LEVEL LOW OVER THE AREA TONIGHT...CIGS EXPECTED TO FALL TO IFR AND VSBYS TO MVFR IN BR FROM LATE THIS EVENING THRU MID MORNING FRI. WITH ALL THE MOISTURE AND DEEP/COOL CYCLONIC CIRCULATION OVER THE AREA...AREAS DZ/-RA AND SCT -SHRA WILL CONTINUE IN/AROUND THE AREA THRU TONIGHT/FRI. PRECIP AMOUNTS LOOK TO BE ON THE LIGHT SIDE...WITH ANY FALLING PRECIP HAVING MINIMAL IMPACT ON VSBYS...MUCH LIKE THE MORNING/MID DAY HOURS TODAY WITH MOST LOCATIONS REPORTING 10SM. CONTINUED A -SHRA MENTION IN TAFS THRU THIS AFTERNOON THEN CARRIED VCSH THRU TONIGHT INTO FRI FOR NOW. WITH THE SFC LOW NEAR/OVERHEAD...WINDS WILL BE SOMEWHAT VARIABLE IN DIRECTION BUT BE ON THE LIGHT SIDE. && .ARX WATCHES/WARNINGS/ADVISORIES... 254 PM CDT THU OCT 18 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...RRS
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1202 PM CDT THU OCT 18 2012 .UPDATE... A VORTICITY MAX ROTATING AROUND A CLOSED UPPER LOW CENTERED OVER THE MN/WI/IA BORDER IS MOVING INTO SOUTHERN WI LATE THIS MORNING. EXPECT THE DRIZZLE AND VERY LIGHT SHOWERS TO EXPAND INTO MORE NUMEROUS LIGHT RAIN SHOWERS DURING THE AFTERNOON. THEY WILL BE SPREADING NORTHEASTWARD FROM IOWA AND NORTHERN IL...AND PROBABLY SKIRT THE SOUTHERN FORECAST AREA. SCATTERED COVERAGE EXPECTED IN THE NORTHERN FORECAST AREA. THE LATEST HRRR SEEMS TO BE PICKING UP ON THIS TREND AS WELL. && .AVIATION/18Z TAFS/... A LARGE AND SLOW MOVING LOW PRESSURE SYSTEM BRINGING MVFR CONDITIONS TO MOST OF THE AREA TODAY. THE COMBINATION OF COLD TEMPS ALOFT...STEEP LOW LEVEL LAPSE RATES AND SHORT WAVE ENERGY WRAPPING AROUND THE UPPER LOW...WILL ALLOW FOR SCATTERED TO NUMEROUS SHOWERS THIS AFTERNOON. AN AREA OF SHOWERS WILL BE MOVING IN FROM EASTERN IOWA AND NORTHWEST IL EARLY THIS AFTERNOON. THE NUMEROUS SHOWERS SHOULD MAINLY SKIRT THE SOUTHERN WI/NORTHERN IL BORDER...WHILE SCATTERED SHOWERS SHOULD BE TOWARD CENTRAL WI FROM MSN NORTH. MVFR CEILINGS SHOULD CONTINUE AT MSN AND PROBABLY UES...WITH INTERMITTENT FUEL ALTERNATE CIGS DURING RAIN SHOWERS. CIGS SHOULD IMPROVE/REMAIN VFR AT MKE AND ENW FOR SEVERAL HOURS THIS AFTERNOON...ALTHOUGH LOW CONFIDENCE ON CIGS DURING RAIN SHOWERS...THEY MAY SLIP BACK INTO MVFR. MVFR CIGS EXPECTED OVERNIGHT WITH THE POSSIBILITY FOR LIGHT SHOWERS. && .PREV DISCUSSION... /ISSUED 331 AM CDT THU OCT 18 2012/ TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM TO HIGH CLASSIC CUT-OFF UPPER LOW WEATHER FOR THE AREA THIS PERIOD. THE UPPER LOW WILL ONLY MOVE FROM SOUTHEAST MINNESOTA THIS MORNING TO SOUTH CENTRAL WISCONSIN BY FRIDAY MORNING. A SERIES OF VORTICITY MAXIMA ROTATING AROUND THE LOW WILL ENHANCE SHOWER CHANCES LATER THIS MORNING AND OVERNIGHT. FOR THIS MORNING...A SHOT OF DRY AIR HAS BEEN WORKING FROM SOUTHWEST TO NORTHEAST AND WILL LIKELY BRING DRY CONDITIONS TO THE CWA BY 12Z THIS MORNING. THEN SHOWERS WILL GRADUALLY SPREAD BACK IN FROM THE WEST BY 15Z AS THE NEXT SHORT WAVE SWINGS AROUND THE UPPER LOW. COLD TEMPS ALOFT WITH STEEP LOW LEVEL LAPSE RATES SHOULD MAKE SHOWER DEVELOPMENT AN EASY EFFORT. THE BEST CHANCE FOR SHOWERS TODAY WILL BE ACROSS THE SOUTH HALF OF THE CWA...SWINGING BACK UP ACROSS THE EASTERN CWA TONIGHT...FOLLOWING THE OVERALL TRACK OF THE UPPER LEVEL FORCING AROUND THE CLOSED LOW. TEMPS MUCH COOLER THAN YESTERDAY...AND COOLEST OUT WEST WHERE THE RAIN WILL ARRIVE EARLIER THAN THE EAST. FRIDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH STACKED LOW PRESSURE SYSTEM CENTERED AROUND THE WI/IL BORDER FRIDAY MORNING WILL MOVE SLOWLY TO THE MI/IN BORDER BY FRIDAY EVENING. THE LOW WILL BE WEAKENING...BUT SHOULD STILL BE ENOUGH LOW LEVEL MOISTURE AND LIFT TO KEEP SHOWERS IN THE AREA. THUS KEPT HIGH CHANCE TO LIKELY POPS GOING THROUGH THE DAY. TEMPS WILL STRUGGLE INTO THE UPPER 40S MOST PLACES GIVEN THE EXPECTED CLOUD COVER...PRECIP...AND COOLER AIRMASS WITH THE LOW. CLOUDS SHOULD DECREASE FRIDAY NIGHT...THOUGH EXPECTING AT LEAST SCATTERED CLOUD COVER TO KEEP LOWS FROM GETTING AS COOL AS POSSIBLE GIVEN COOLER AIR ALOFT. SATURDAY AND SUNDAY...FORECAST CONFIDENCE...MEDIUM TO HIGH TEMPERATURES SHOULD WARM TO NEAR NORMAL SATURDAY THEN A FEW DEGREES ABOVE NORMAL SUNDAY AS UPPER RIDGING BUILDS INTO THE AREA. SHOULD BE DRY THROUGH THE WEEKEND...THOUGH LINGERING LOW LEVEL MOISTURE AND COOLER AIR ALOFT SHOULD ALLOW FOR SCATTERED TO BROKEN DIURNAL CUMULUS SATURDAY. SHOULD SEE MORE SUNSHINE ON SUNDAY. MONDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE...MEDIUM MODELS IN SOMEWHAT BETTER AGREEMENT FOR THE FIRST HALF OF NEXT WEEK. OVERALL...LOOKS LIKE MILDER AIR WILL PERSIST IN THE REGION...THOUGH ECMWF AND GFS GOING BACK AND FORTH WITH ARRIVAL OF COOLER AIR BY MID WEEK. WENT WITH SHOWER AND STORM CHANCES THROUGH WEDNESDAY DUE TO THE COMBINATION OF WARM AIR ADVECTION AND MULTIPLE SHORTWAVES WITHIN THE FLOW. AVIATION/12Z TAFS/... A LARGE AND SLOW MOVING LOW PRESSURE SYSTEM WILL BRING MVFR CONDITIONS TO THE AREA THROUGH MOST OF THE TAF PERIOD. VFR CONDITIONS AROUND THE AREA EARLY THIS MORNING...WILL BE REPLACED BY THE MVFR CIGS MOVING IN FROM THE WEST. THE COMBINATION OF COLD TEMPS ALOFT...STEEP LOW LEVEL LAPSE RATES AND SHORT WAVE ENERGY WRAPPING AROUND THE UPPER LOW...WILL BRING INCREASING CHANCES OF SHOWERS THROUGH DAY...CONTINUING INTO TONIGHT. MARINE...BREEZY SOUTHWEST WINDS ON THE SOUTH SIDE OF A LARGE LOW PRESSURE SYSTEM LIFTING INTO NORTHERN WISCONSIN WILL REQUIRE AN EXTENSION OF THE SMALL CRAFT ADVISORY INTO THIS EVENING. THE LOW WILL BEGIN TO WEAKEN WITH THE WINDS AND WAVE DIMINISHING TONIGHT. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LMZ643>646. && $$ UPDATE...MRC TODAY/TONIGHT AND AVIATION/MARINE...DAVIS FRIDAY THROUGH WEDNESDAY...DDV
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
322 AM CDT THU OCT 18 2012 .SHORT TERM...TODAY THROUGH SATURDAY NIGHT 322 AM CDT THU OCT 18 2012 MAIN FORECAST CONCERNS REMAIN ON RAIN CHANCES TODAY THROUGH FRIDAY. LATEST WATER VAPOR IMAGERY SHOWED A LARGE UPPER LEVEL LOW OVER THE UPPER MISSISSIPPI RIVER VALLEY...CENTERED MAINLY OVER NORTHWEST/WEST CENTRAL MINNESOTA. A POTENT TROUGH WAS PUSHING EAST OUT OF THE MIDDLE MISSISSIPPI RIVER VALLEY INTO THE APPALACHIANS. RADAR IMAGERY SHOWED A BAND OF SHOWERS ACROSS THE EASTERN HALF OF WISCONSIN MOVING NORTHWEST IMPACTING LOCATIONS ACROSS CENTRAL INTO NORTH CENTRAL WISCONSIN. A DRY SLOT WAS NOTED ACROSS EASTERN IOWA/WESTERN WISCONSIN...INTO NORTH CENTRAL MINNESOTA. SHOWERS WERE WRAPPING AROUND THE BACK SIDE OF THE LOW ACROSS EASTERN NORTH DAKOTA/SOUTH DAKOTA. SCATTERED SHOWERS WERE DEVELOPING OVER CENTRAL INTO SOUTHEAST MINNESOTA MOVING SOUTHEAST. THE UPPER LOW WILL BE THE DOMINANT WEATHER FEATURE ACROSS THE REGION TODAY AS IT DEEPENS AND SLIDES SOUTHEAST AND CENTERS OVER THE FORECAST AREA. THE DRY SLOT WILL GRADUALLY BE OVERCOME TODAY AS THE LOW WRAPS UP. LOOK FOR SHOWERS TO SLIDE BACK INTO THE FORECAST AREA FROM THE NORTHWEST AND WEST TODAY AS THE LOW MOVES IN. RATHER LIGHT PRECIPITATION AMOUNTS NOTED IN THE FORECAST MODELS TODAY THANKS TO WEAK LIFT WITH THE LOW DIRECTLY OVERHEAD. LAPSE RATES STEEPEN CONSIDERABLY THIS AFTERNOON...850-700MB LAPSE RATES AROUND 7 DEGREES C/KM...SO WOULD EXPECT SCATTERED TO NUMEROUS RAIN SHOWERS TO DEVELOP ACROSS THE FORECAST AREA. OTHERWISE...DRIZZLE OR LIGHT RAIN WILL BE SEEN EARLY TODAY BEFORE THE STEEP LAPSE RATES MOVE IN DURING THE AFTERNOON HOURS. WILL HAVE TO KEEP A CLOSE WATCH ON SURFACE BASED CAPE THIS THIS AFTERNOON WITH THE OUTSIDE CHANCE OF A COLD AIR FUNNEL. WOULDNT EXPECT TO SEE THEM TODAY WITH THE COOL SURFACE TEMPS AND LACK OF APPRECIABLE CAPE. PLAN ON A COOL AND CLOUDY DAY TODAY WITH HIGHS ONLY IN THE 40S. THE CENTER OF THE LOW IS EXPECTED TO DRIFT SOUTH TONIGHT OVER NORTHERN ILLINOIS...BUT GIVEN THE EXPANSIVE AREA OF THE LOW ENCOMPASSING MUCH OF THE GREAT LAKES REGION INTO THE MID MISSISSIPPI RIVER VALLEY...IT WILL CONTINUE TO CONTROL THE WEATHER ACROSS THE AREA. THE CONVECTIVE SHOWERS SHOULD TAPER OFF AROUND SUNRISE. FORECAST SOUNDINGS CONTINUE TO SHOW A NEARLY SATURATED LAYER FROM THE SURFACE THROUGH AROUND 800 MB SO CANNOT RULE OUT SOME DRIZZLE OVERNIGHT. HAVE DECREASED MEASURABLE PRECIPITATION CHANCES OVER THE PREVIOUS FORECAST. PLAN ON SOME AREAS OF DRIZZLE TONIGHT WITH THE POSSIBILITY OF ISOLATED SHOWERS. OTHERWISE...PLAN ON CLOUDY SKIES OVERNIGHT WITH LOW TEMPERATURES FALLING INTO THE UPPER 30S TO LOWER 40S. A POTENT SHORTWAVE ROTATING AROUND THE NORTH SIDE OF THE LOW IS EXPECTED TO PUSH INTO NORTHWESTERN SECTIONS OF THE FORECAST AREA FRIDAY MORNING THEN PROGRESS SOUTHEAST THROUGH THE MORNING HOURS...GENERATING SHOWERS AS IT MOVES THROUGH. THE WAVE WILL QUICKLY EXIT THE AREA FRIDAY AFTERNOON MOVING INTO SOUTHEAST IOWA/NORTHERN ILLINOIS BY LATE AFTERNOON. ANY LINGERING RAIN SHOWERS WILL END LATE FRIDAY AFTERNOON. CLOUD COVER WILL BE A BIT OF A CHALLENGE FRIDAY NIGHT INTO SATURDAY MORNING WITH LINGERING LOW LEVEL MOISTURE AND CYCLONIC FLOW ALOFT. UPPER LEVEL RIDGING WILL BE BUILDING IN ACROSS MINNESOTA LATE FRIDAY NIGHT THEN SLIDING INTO WESTERN WISCONSIN SATURDAY MORNING AS THE UPPER LOW EXITS TO THE EASTERN GREAT LAKES. IF THE CLOUDS CAN CLEAR AREAS OF FOG MAY DEVELOP LATE FRIDAY NIGHT INTO EARLY SATURDAY MORNING. PLAN ON LOW TEMPERATURES FALLING INTO THE 30S. CLOUDS ARE EXPECTED TO DECREASE ACROSS THE AREA SATURDAY MORNING INTO SATURDAY AFTERNOON AS THE RIDGE MOVES OVER THE UPPER MISSISSIPPI RIVER VALLEY. PLAN ON MOSTLY SUNNY SKIES BY SATURDAY AFTERNOON. HIGHS ON SATURDAY WILL RANGE FROM THE LOWER 50S ACROSS NORTHERN WISCONSIN TO THE UPPER 50S OVER NORTHEAST IOWA. 925 MB TEMPERATURES WARM SATURDAY NIGHT INTO SUNDAY MORNING...FROM AROUND 9C AT 00Z SUN TO AROUND 12 C BY 12Z. THIS WILL SET THE STAGE FOR RATHER PLEASANT DAY ON SUNDAY. .LONG TERM...SUNDAY THROUGH WEDNESDAY 322 AM CDT THU OCT 18 2012 18.00 MEDIUM RANGE MODELS SHOW A PLEASANT DAY ON TAP FOR SUNDAY WITH MOSTLY SUNNY SKIES AND HIGHS CLIMBING INTO THE 60S. AN ACTIVE PATTERN WILL THEN TAKE HOLD ON THE REGION SUNDAY NIGHT THROUGH THE MIDDLE OF NEXT WEEK AS A BAROCLINIC ZONE SETS UP ACROSS THE REGION AND FLOW ALOFT TURNS SOUTHWEST AS A TROUGH DEVELOPS OVER THE WESTERN CONUS. THE EXACT LOCATION OF THE BAROCLINIC ZONE IS DIFFICULT TO PIN POINT AT THIS TIME BUT CURRENT THINKING IS THAT IT WILL STRETCH FROM THE CENTRAL PLAINS...NEBRASKA/KANSAS...NORTHEAST INTO THE UPPER MISSISSIPPI RIVER VALLEY. SHORTWAVES MOVING THROUGH THE SOUTHWEST FLOW ALOFT WILL INTERACT WITH THIS BOUNDARY PRODUCING PERIODIC SHOWER AND THUNDERSTORM CHANCES. FORECAST MODELS ARE IN REASONABLE AGREEMENT SUNDAY NIGHT INTO MONDAY. THE FIRST WAVE IS EXPECTED TO MOVE ACROSS THE CENTRAL PLAINS AND INTO THE FORECAST AREA SUNDAY NIGHT WITH THE BOUNDARY LIFTING NORTH INTO SOUTHERN MINNESOTA/SOUTHERN WISCONSIN. THE ECMWF IS SHOWING 0-3KM MUCAPE VALUES INCREASING TO AROUND 1300J/KG ACROSS LOCATIONS WEST OF THE MISSISSIPPI RIVER WITH 0-6 KM BULK SHEAR VALUES AROUND 30 KTS. DECIDED TO GO WITH SHOWERS AND THUNDERSTORMS ACROSS MUCH OF SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND FAR SOUTHWEST WISCONSIN. THINKING WEST CENTRAL INTO CENTRAL WISCONSIN WOULD SEE ISOLATED THUNDERSTORMS WITH THE HIGHEST INSTABILITY OFF TO THE SOUTHWEST. THE FRONT IS EXPECTED TO LIFT NORTH INTO NORTHERN WISCONSIN MONDAY NIGHT. ANOTHER WAVE LOOKS TO MOVE THROUGH DURING THE DAY ON TUESDAY...DRAGGING A COLD FRONT ACROSS THE FORECAST AREA. COULD SEE ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS AS THE FRONT MOVES THROUGH. DEPENDING ON THE INSTABILITY AND HOW FAR NORTH THE WARM FRONT GETS MONDAY NIGHT...THERE IS THE OUTSIDE CHANCE THAT THE STORMS COULD BE STRONG TO SEVERE WITH 0-6KM BULK SHEAR OF 40 TO 50 KTS AND 0-3KM MUCAPE VALUES AROUND 1500 J/KG. THE COLD FRONT IS EXPECTED TO SLIDE SOUTHEAST INTO NORTHERN ILLINOIS/SOUTHERN IOWA TUESDAY NIGHT INTO WEDNESDAY TAKING THE INSTABILITY BACK TO THE SOUTH. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL PERSIST INTO WEDNESDAY AS SOUTHWEST FLOW ALOFT CONTINUES. && .AVIATION...THROUGH 06Z FRIDAY 1138 PM CDT WED OCT 17 2012 AREA OF SURFACE LOW PRESSURE REMAINING NEARLY STATIONARY THIS EVENING NORTH OF KGFK. COLD FRONT EXTENDS SOUTHEAST FROM THE LOW INTO SOUTHEAST WISCONSIN. PLENTY OF MOISTURE REMAINS IN PLACE BEHIND THE FRONT AND WITH THE CYCLONIC FLOW AND PERSISTENT WEAK ISENTROPIC UP GLIDE ON THE 295K SURFACE...AN EXPANSIVE CLOUD DECK IS IN PLACE. CEILINGS ARE SLOWLY LOWERING AND EXPECT BOTH TAF SITES TO BE AT OR NEAR MVFR BY ISSUANCE TIME. OBSERVATIONS ACROSS CENTRAL AND WESTERN MINNESOTA INDICATE THE HEIGHTS SHOULD CONTINUE TO LOWER BUT REMAIN MVFR THROUGH THE NIGHT. SOME IFR CONDITIONS HAVE PERSISTED OVER NORTHERN MINNESOTA...GENERALLY ALONG AND NORTH OF THE FRONT. THESE WILL HAVE TO BE MONITORED AS THERE IS THE POTENTIAL FOR THEM TO PUSH INTO KRST AS THE SURFACE LOW WEAKENS AND BEGINS TO MOVE SOUTHEAST. SOME LIGHT RAIN SEEN ON RADAR OVER THE EASTERN DAKOTAS HAS MADE LITTLE EASTWARD PROGRESS BUT THE 18.01Z HRRR AND 18.00Z NAM SUGGEST SOME OF THIS COULD GET INTO THE REGION LATE TONIGHT SO WILL SHOW VCSH FOR BOTH TAF SITES. BETTER CHANCE OF SOME PERSISTENT LIGHT RAIN STARTING THURSDAY MORNING AND CONTINUING THROUGH THE AFTERNOON AS THE NAM SHOWS A SHORT WAVE TROUGH ROTATING AROUND THE UPPER LEVEL LOW TO PROVIDE A LITTLE EXTRA FORCING TO THE ISENTROPIC UP GLIDE AND WILL CARRY PREVAILING LIGHT RAIN WITHOUT A VISIBILITY RESTRICTION. SHOULD SEE THE WINDS SWING AROUND TO THE NORTHWEST AT KRST WHILE GOING LIGHT AT KLSE LATE THURSDAY AFTERNOON AS THE REMAINS OF THE SURFACE LOW MOVES THROUGH THE AREA. && .ARX WATCHES/WARNINGS/ADVISORIES... 322 AM CDT THU OCT 18 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1138 PM CDT WED OCT 17 2012 .SHORT TERM...TONIGHT THROUGH SATURDAY 217 PM CDT WED OCT 17 2012 FORECAST CONCERNS THROUGH THE SHORT TERM INCLUDE RAIN CHANCES AND TEMPERATURES. WATER VAPOR SATELLITE LOOP SHOWING DEEPENING MID-LEVEL LOW/TROUGH OVER THE EASTERN DAKOTAS EXTENDING SOUTHWARD INTO EASTERN NEBRASKA AND KANSAS. AT THE SURFACE...LOW PRESSURE WAS SITUATED OVER NORTHERN MN WITH A COLD FRONT EXTENDING SOUTHWARD ALONG THE MISSISSIPPI RIVER AND THEN ACROSS EASTERN IA/CENTRAL MO. RADAR MOSAIC SHOWING SCATTERED SHOWERS AND A FEW THUNDERSTORMS ACROSS EASTERN IA INTO CENTRAL WI IN LIFT AHEAD OF THE ADVANCING COLD FRONT. LATEST NCEP MODELS/ECMWF/GEM ALL IN PRETTY GOOD AGREEMENT WITH HANDLING OF DEEP/CLOSED LOW THROUGH THE PERIOD. JET ENERGY COMING OUT OF THE BASE OF THE TROUGH OVER THE CENTRAL PLAINS WILL RACE NORTHEAST WITH A 100KT 300MB JETLET OVER WESTERN WI BY 03Z PER THE NAM. DIRECT CIRCULATION ASSOCIATED WITH THE RIGHT ENTRANCE REGION OF THIS JET ACTS TO ENHANCE 850-500MB FRONTOGENETIC CIRCULATION ACROSS CENTRAL/EASTERN WI. THIS SHOULD IN TURN ACT TO ENHANCE BAND OF SHOWERS/ISOLATED THUNDERSTORMS. BELIEVE AREAS EAST OF A MAUSTON TO BOSCOBEL WILL SEE MOST OF THIS ACTIVITY. AFTER MIDNIGHT THIS FORCING GETS DISPLACED NORTHEAST...PUSHING MOST OF THE SHOWERS OUT OF THE AREA AS DRY SLOT OF THE DEEP LOW OVERTAKES THE AREA. KEPT SHOWER CHANCES NORTHEAST OF I-94 IN THE 06-12Z TIME FRAME. TOWARD MORNING...THETA-E TROWAL WRAPPING AROUND THE CLOSED LOW EXPECTED TO SPREAD SHOWERS SOUTHEASTWARD ACROSS THE DAKOTAS/SOUTHERN MN. EASTERN NOSE OF THESE SHOWERS MAY MAKE IT INTO OUR FAR WESTERN FORECAST AREA. WILL GO WITH A 20-30 POP TO COVER THIS. OTHERWISE...LOOK FOR OVERNIGHT LOWS BOTTOMING OUT IN THE 40S. FOR THURSDAY THROUGH FRIDAY...THE CLOSED LOW WILL REMAIN ANCHORED OVER WI FOR COOLER/BELOW NORMAL TEMPERATURES ALONG WITH SCATTERED SHOWERS. LOOK FOR ONLY AROUND A 5 DEGREE DIURNAL RISE MOST LOCATIONS ON THURSDAY WITH HIGHS IN THE 40S. LOWS THURSDAY NIGHT EXPECTED TO DIP TO AROUND 40 WITH FRIDAY REMAINING AROUND 10 DEGREES BELOW NORMAL AS HIGHS TOP OF AROUND 50. FOR FRIDAY NIGHT THROUGH SATURDAY...THE CLOSED LOW MOVES INTO THE EASTERN GREAT LAKES WITH A RIDGE OF HIGH PRESSURE BUILDING IN FROM THE PLAINS. SKY TRENDS COULD BE A BIT TRICKY THROUGH THIS PERIOD AS THE NAM LOW-LEVEL RH FIELD/BUFKIT SOUNDING HINTING AT STRATUS GETTING TRAPPED UNDER THE SUBSIDENCE INVERSION. CLIMATOLOGICALLY... WITH THE LOWER SUN ANGLE/LESS MIXING...THIS SEEMS TO MAKE SENSE. DESPITE THE RIDGE BUILDING IN...WILL DELAY CLEARING UNTIL LATER SATURDAY AFTERNOON AS THE BACK SIDE OF THE RIDGE AXIS PRODUCES SOUTHERLY FLOW TO MIX OUT THE STRATUS. THIS WILL ALSO HAVE AN IMPACT ON TEMPERATURES AS WELL...ESPECIALLY HIGHS ON SATURDAY. BASED ON CLOUD TREND...WILL KEEP HIGHS IN THE 50S. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY 217 PM CDT WED OCT 17 2012 LATEST GFS AND ECMWF SHOWING MID/UPPER LEVEL RIDGE MOVING EAST ACROSS THE AREA SATURDAY NIGHT/SUNDAY. THIS ALLOWS A COLD FRONT TO MOVE FROM THE NORTHERN PLAINS INTO THE UPPER MISSISSIPPI RIVER REGION BY SUNDAY AFTERNOON. SOUTHERLY FLOW/WARM AIR ADVECTION AHEAD OF THE COLD FRONT EXPECTED TO PUSH TEMPERATURES INTO THE 60S FOR HIGHS ON SUNDAY UNDER MOSTLY SUNNY SKIES. MODELS THEN START TO DIVERGE A BIT WITH PLACEMENT OF THE COLD FRONTAL BOUNDARY SUNDAY NIGHT THROUGH WEDNESDAY WITH SOUTHWEST FLOW ALOFT. GFS PUSHES THE FRONT FARTHER SOUTH OF THE AREA THEN THE ECMWF. BOTH MODELS SHOWING A COUPLE WAVES OF LOW PRESSURE MOVING UP ALONG THIS FRONTAL BOUNDARY FOR SHOWER/THUNDER CHANCES. BEST CHANCE FOR THUNDER APPEARS TO BE MONDAY INTO MONDAY NIGHT. OTHERWISE...LOOKS LIKE TEMPERATURES SHOULD REMAIN A FEW DEGREES ABOVE NORMAL WITH HIGHS MAINLY IN THE 60S AND OVERNIGHT LOWS MAINLY IN THE 40S. && .AVIATION...THROUGH 06Z FRIDAY 1138 PM CDT WED OCT 17 2012 AREA OF SURFACE LOW PRESSURE REMAINING NEARLY STATIONARY THIS EVENING NORTH OF KGFK. COLD FRONT EXTENDS SOUTHEAST FROM THE LOW INTO SOUTHEAST WISCONSIN. PLENTY OF MOISTURE REMAINS IN PLACE BEHIND THE FRONT AND WITH THE CYCLONIC FLOW AND PERSISTENT WEAK ISENTROPIC UP GLIDE ON THE 295K SURFACE...AN EXPANSIVE CLOUD DECK IS IN PLACE. CEILINGS ARE SLOWLY LOWERING AND EXPECT BOTH TAF SITES TO BE AT OR NEAR MVFR BY ISSUANCE TIME. OBSERVATIONS ACROSS CENTRAL AND WESTERN MINNESOTA INDICATE THE HEIGHTS SHOULD CONTINUE TO LOWER BUT REMAIN MVFR THROUGH THE NIGHT. SOME IFR CONDITIONS HAVE PERSISTED OVER NORTHERN MINNESOTA...GENERALLY ALONG AND NORTH OF THE FRONT. THESE WILL HAVE TO BE MONITORED AS THERE IS THE POTENTIAL FOR THEM TO PUSH INTO KRST AS THE SURFACE LOW WEAKENS AND BEGINS TO MOVE SOUTHEAST. SOME LIGHT RAIN SEEN ON RADAR OVER THE EASTERN DAKOTAS HAS MADE LITTLE EASTWARD PROGRESS BUT THE 18.01Z HRRR AND 18.00Z NAM SUGGEST SOME OF THIS COULD GET INTO THE REGION LATE TONIGHT SO WILL SHOW VCSH FOR BOTH TAF SITES. BETTER CHANCE OF SOME PERSISTENT LIGHT RAIN STARTING THURSDAY MORNING AND CONTINUING THROUGH THE AFTERNOON AS THE NAM SHOWS A SHORT WAVE TROUGH ROTATING AROUND THE UPPER LEVEL LOW TO PROVIDE A LITTLE EXTRA FORCING TO THE ISENTROPIC UP GLIDE AND WILL CARRY PREVAILING LIGHT RAIN WITHOUT A VISIBILITY RESTRICTION. SHOULD SEE THE WINDS SWING AROUND TO THE NORTHWEST AT KRST WHILE GOING LIGHT AT KLSE LATE THURSDAY AFTERNOON AS THE REMAINS OF THE SURFACE LOW MOVES THROUGH THE AREA. && .ARX WATCHES/WARNINGS/ADVISORIES... 217 PM CDT WED OCT 17 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...04
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1155 PM CDT FRI OCT 19 2012 .DISCUSSION... ISSUED 855 PM CDT FRI OCT 19 2012 UPDATED THE FORECAST THIS EVENING TO INCREASE CHANCE OF SHOWERS FROM LINCOLN NORTHEAST AND ALSO ADDED PATCHY FOG LATE TONIGHT NORTH OF LINCOLN WITH SOME DECREASING LOW CLOUDS LATE. COOLED LOWS CLOSER TO 40F OVER THE IL RIVER VALLEY WITH 40 TO 45F MOST REST OF CENTRAL AND SE IL. WEST WINDS OF 8 TO 16 MPH THIS EVENING DIMINISHING TO 5 TO 10 MPH OVERNIGHT. LOW CLOUDS BLANKET CENTRAL AND SE IL THIS EVENING. STRONG 538 DM 500 MB LOW OVER SOUTHERN LAKE MI HAS A FAIRLY STRONG SHORT WAVE OVER NW IL PIVOTING SE INTO CENTRAL IL DURING MID EVENING WITH ONE MORE BATCH OF SHOWERS AFFECTING AREAS FROM LINCOLN NE UNTIL MIDNIGHT. POCKETS OF HEAVIER RAIN NE OF I-74 AND HAD A REPORT OF PEA SIZE GRAPEL (SOFT HAIL) AT HOOPESTON AT 555 PM. 1001 MB SURFACE LOW WAS OVER SE LAKE MICHIGAN AND GRADUALLY WEAKENING TODAY SINCE LOW PRESSURE SYSTEM IS NEARLY VERTICALLY STACKED. COOL TEMPS CURRENTLY IN THE UPPER 40S AND LOWER 50S WITH WSW WINDS 8 TO 16 MPH AND A FEW GUSTS NEAR 20 MPH. THE HRRR MODEL HANDLED QPF FIELDS THE BEST AND USED IT FOR THE FORECAST UPDATE THIS EVENING WITH LIKELY CHANCES OF SHOWERS OVER AREAS NE OF LINCOLN UNTIL MIDNIGHT. COULD BE A FEW LINGERING LIGHT RAIN SHOWERS OR DRIZZLE EARLY OVERNIGHT FROM LINCOLN EAST. A LARGE BREAK IN THE LOW CLOUDS OVER THE UPPER MS VALLEY OF NE IA...EASTERN MN AND WESTERN WI TO TRACK SSE INTO THE IL RIVER VALLEY LATER TONIGHT SO DECREASED CLOUDS THERE TO BECOME PARTLY CLOUDY LATE AND ADDED PATCHY FOG LATE TONIGHT UNTIL MID MORNING SAT NORTH OF LINCOLN. MODELS TAKE LOW PRESSURE JUST EAST OF SE PARTS OF LOWER MI BY SUNRISE AND INTO SE ONTARIO BY 18Z/SAT. SO SHOWERS TO DIMINISH BY EARLY OVERNIGHT WITH LOW CLOUDS DECREASE FROM NW TO SE LATER TONIGHT AND SAT MORNING. LOWS MOSTLY 40 TO 45F...CLOSER TO 40F OVER THE IL RIVER VALLEY WHERE SOME DECREASING CLOUDS EXPECTED LATER. 07 && .AVIATION... ISSUED 1155 PM CDT FRI OCT 19 2012 MVFR TO IFR CEILINGS WILL PREVAIL ACROSS THE CENTRAL IL AIRPORTS DURING PART OF OVERNIGHT. A LINGERING BAND OF SHOWERS IS STILL AFFECTING BMI AND ESPECIALLY CMI NEXT HOUR OR TWO WITH VSBYS REDUCED TO MVFR AT TIMES WITH SHOWERS. MOST OF THESE SHOWERS SHOULD EXIT SE INTO CENTRAL INDIANA BY 07Z/2 AM AS SHORT WAVE EXITS SE FROM EAST CENTRAL IL INTO THE CENTRAL OHIO VALLEY DURING OVERNIGHT. STRONG 539 DM 500 MB LOW AND CORRELATING 1002 SURFACE LOW WAS OVER SOUTH CENTRAL/SW LOWER MI AND TO CONTINUE TO SLOWLY WEAKEN AS IT LIFTS NE INTO SOUTHEAST ONTARIO SAT. FOG DEVELOPMENT A CONCERN ESPECIALLY AT NORTHERN AIRPORTS OF PIA AND BMI LATER TONIGHT AFTER 09Z UNTIL MID MORNING SAT AS A LARGE CLEARING AREA OF THE LOW CLOUDS WAS SHIFTING SSE FROM THE UPPER MS VALLEY ALREADY INTO NORTHERN IL LATE THIS EVENING. LOWERED VSBYS TO BETWEEN 1/2 AND 1 MILE LATER TONIGHT AT PIA AND BMI WHILE VSBYS SHOULD BE 1-3 MILES ALONG I-72 AIRPORTS WHERE LESS CLEARING EXPECTED FURTHER SOUTH. REMAINING LOW CLOUDS TO ELEVATE TO VFR AND SCATTER OUT ACROSS AREA LATER SAT MORNING WITH FAIR SKIES EXPECTED BY SAT EVENING. WEST WINDS 7-11 KTS TO TURN WSW AT 5-10 KTS SAT AND THEN SSE NEAR 5 KTS BY SUNSET SAT AS WEAK HIGH PRESSURE RIDGES MOVES INTO THE MID MS AND OHIO VALLEYS. 07 && .PREV DISCUSSION... ISSUED 254 PM CDT FRI OCT 19 2012 THE CHILLY CUT-OFF LOW WILL FINALLY MAKE AN EXIT TO THE EAST BY SATURDAY MORNING...BRINGING AN END TO THIS ROUND OF COLD RAIN/DRIZZLE TOWARD MIDNIGHT TONIGHT. CLOUDS WILL BE TOUGH TO CLEAR OUT...BUT SUNSHINE SHOULD DEVELOP ON SATURDAY...HELPING TO JUMP START OUR WARMING TREND. AN EXTENDED PERIOD OF ABOVE NORMAL TEMPS WILL HIGHLIGHT THE EXTENDED FORECAST FROM SUNDAY THROUGH THURSDAY. A LATE WEEK COLD FRONT WILL BRING NUMBERS BACK TOWARD OR BELOW NORMAL FOR FRIDAY AND INTO NEXT WEEKEND. RAIN CHANCES WILL BE FOCUSED FROM MONDAY THROUGH TUES WITH STRONG WARM ADVECTION AND A NEARBY LOW PRESSURE/FRONTAL SYSTEM...AND AGAIN WITH THE THURS/THUR NIGHT COLD FRONT. SHORT TERM...TONIGHT THROUGH TUESDAY. THE CHILLY AIRMASS WITH 850MB TEMPS AROUND -1C OVERHEAD IS HELPING PRODUCE FAVORABLE CONDITIONS FOR SHOWERY PRECIP. THE HEAVIER SHOWERS ARE BEING DRIVEN BY 500MB SHORTWAVES...THE NEXT OF WHICH IS APPROACHING OUR NW COUNTIES FROM IOWA. THAT WAVE WILL KEEP SHOWER CHANCES THROUGH THE EVENING ACROSS ALL OF C/SE IL. AS MIXING DIMINISHES AFTER SUNSET...STRATUS AND DRIZZLE MAY BECOME MORE PROMINENT. THE BULK OF THE PRECIP SHOULD BE DONE BY MIDNIGHT...BUT CANT RULE OUT SOME LINGERING DRIZZLE AFTER MIDNIGHT ACROSS THE NORTHEAST. A BLANKET OF LOW CLOUDS WILL REMAIN THROUGH SATURDAY MORNING. CLEARING WILL BEGIN SATURDAY MORNING WITH THE HEATING OF THE DAY AND MIXING OF DRY AIR FROM JUST ABOVE THE CLOUD LAYER. INCREASING SUNSHINE BY AFTERNOON WILL HELP PUSH TEMPS ABOUT 10 DEG F ABOVE TODAY/S READINGS...WITH HIGHS IN THE LOW 60S. MORE SIGNIFICANT WARMING IS ON TAP FOR SUNDAY...WITH PLENTY OF SUNSHINE. HIGHS SHOULD TOP OUT ANOTHER 10-13F ABOVE SATURDAY...WITH READINGS IN THE LOW TO MID 70S. HOWEVER...THE STRONG MID LEVEL WARM ADVECTION WILL ALSO BE ACCOMPANIED BY STRONG MOISTURE FLUX AS WELL. SURFACE DEWPOINTS WILL LIKEWISE CLIMB INTO THE LOWER 60S...AIDING IN POSSIBLE SHOWERS AND THUNDERSTORMS SUNDAY NIGHT. SHOWER/STORM DEVELOPMENT WILL BE ENHANCED BY A SURFACE LOW MOVING OUT OF THE PLAINS UP THROUGH IOWA BY SUNDAY NIGHT AND MONDAY MORNING. INSTABILITY PARAMS SUPPORT THUNDERSTORM DEVELOPMENT... ESPECIALLY DUE TO THE RELATIVELY HIGH SURFACE DEWPOINTS ACCOMPANIED WITH FAVORABLE WIND SHEAR. THE PRECIP CHANCES WILL BE SUSTAINED INTO TUESDAY AS THE REMNANTS OF A TROPICAL SYSTEM /CURRENTLY OFF OF THE BAJA OF CALIFORNIA/ TRAIL INTO OUR AREA QUICKLY ON THE HEELS OF THE INITIAL LOW PRESSURE SYSTEM. LONG TERM...WEDNESDAY THROUGH FRIDAY. THE MAIN EXTENDED FORECAST ISSUE WILL BE TIMING OF THE COLD FRONT FOR EITHER THURSDAY /ECMWF & CANADIAN GEM/ OR THURSDAY NIGHT /GFS/. AHEAD OF THE FRONT...THERE IS GOOD AGREEMENT THAT WED WILL BE A DRY AND WARM DAY...WITH HIGHS POSSIBLY THE WARMEST OF THE NEXT WEEK. SOME UPPER 70S IN OUR SW AREA WITH AT LEAST MID 70S ALL ACROSS OUR AREA. SOME QUESTION MARKS REMAIN FOR THURSDAY HIGHS...DEPENDING IF PRECIP RETURNS EARLY OR LATE THURSDAY. WE WENT WITH THE PREMISE THAT EVEN WITH REDUCED SUNSHINE...ENOUGH BURN-THROUGH HEATING SHOULD PUSH HIGHS INTO THE LOWER 70S. THE PASSAGE OF THE COLD FRONT WILL BRING AN AIRMASS CHANGE FOR FRIDAY AND THROUGH NEXT WEEKEND. TEMPS WILL LIKELY DIP BELOW NORMAL FOR THE WEEKEND AND POSSIBLY INTO EARLY NEXT WEEK AS A DEEP TROUGH BECOME ESTABLISHED IN THE MIDWEST ONCE AGAIN. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1129 PM CDT FRI OCT 19 2012 .AVIATION... A CHALLENGING AVIATION FORECAST IS IN STORE FOR THE NEXT 10 HOURS...AS HIGH PRESSURE MOVES IN...CLEARING SKIES...BUT ALSO ALLOWING FOR WIDESPREAD IFR/LIFR CONDITIONS TO DEVELOP. IT NOW APPEARS THAT MINIMUM CONDITIONS ARE LIKELY AT MLI/CID/DBQ THROUGH 13Z...POSSIBLY 14Z. 1/4MI VISIBILITY AND VV001/BKN003 CONDITIONS WILL BE COMMON THROUGH 13Z. AFTER SUNRISE...OR AFT 13Z/20...A PERIOD OF VFR CLEAR/UNLIMITED WEATHER IS FORECAST FROM THE HIGH PRESSURE. ERVIN && .PREV DISCUSSION... /ISSUED 258 PM CDT FRI OCT 19 2012/ SYNOPSIS... 12Z UA ANALYSIS HAS THE UPPER LOW OVER WISCONSIN WITH NUMEROUS TROFS FROM THE OHIO VALLEY BACK INTO THE PLAINS AND UPPER MIDWEST. SATELLITE/RADAR TRENDS THROUGH MID AFTERNOON SHOWS THE INITIAL SUBSIDENCE HAS FILLED BACK IN WITH DIURNAL CLOUDS. A VORT MAX ROTATING SOUTHEAST OUT OF MINNESOTA IS HELPING TO GENERATE NEW SHOWERS/SPRINKLES. 18Z SFC ANALYSIS HAS A LOW OVER SOUTHERN LAKE MICHIGAN WEST OF KBIV. NUMEROUS TROFS RAN FROM THE LOW FROM THE LOWER OHIO VALLEY BACK UP THROUGH WISCONSIN AND MINNESOTA. DEW POINTS WERE IN THE 30S AND 40S ACROSS THE MIDWEST. SHORT TERM...LATE THIS AFTERNOON THROUGH SATURDAY... THE VORT MAX HELPING TO GENERATE THE SHRA ACTIVITY ACROSS THE CWFA IS FURTHER TO THE NORTH/EAST THAN WHAT THE RAP WAS SUGGESTING EARLIER TODAY. BASED ON THE CURRENT AND EXTRAPOLATED POSITION OF THE SHRA ACTIVITY...THERE SHOULD BE AN AREA OF CONCENTRATED SHOWERS BETWEEN KDBQ/KALO TO THE SOUTHEAST LATE THIS AFTERNOON. SAID ACTIVITY WILL CONTINUE INTO THE EARLY EVENING FROM NORTHEAST OF KIOW DOWN TOWARDS KGBG BEFORE DISSIPATING LATER THIS EVENING. AROUND THIS BAND OF CONCENTRATED SHRA ACTIVITY ISOLATED TO LOW END SCATTERED DIURNAL SHRA WILL BE SEEN THAT DISSIPATE SHORTLY AFTER SUNSET. BASED ON THE LUMPY NATURE OF THE CLOUDS ON SATELLITE...SUBSIDENCE AND THE SETTING SUN WILL RESULT IN A CLEARING POCKET THAT DEVELOPS ACROSS MN AND WESTERN WISCONSIN THAT SHOULD BEGIN ROTATING SOUTH AND THEN SOUTHEAST ACROSS THE CWFA BY LATE EVENING WITH PARTIAL CLEARING CONTINUING OVERNIGHT. WINDS WILL DIMINISH BUT NOT AS MUCH AS LAST NIGHT. HOWEVER...IN SHELTERED AREAS AND SOME RIVER VALLEYS THERE IS A POTENTIAL FOR PATCHY FOG TO DEVELOP LATE TONIGHT. IF FOG DEVELOPS LATE TONIGHT IT WILL LINGER INTO EARLY SATURDAY MORNING BEFORE BURNING OFF. SATURDAY WILL BE A MUCH NICER DAY WITH SUNSHINE...POSSIBLY FILTERED...WITH TEMPERATURES CLOSE TO NORMAL. 08 LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY... FLOW PATTERN ALOFT WILL TRANSITION TO SOUTHWESTERLY FLOW BY EARLY IN THE WEEK. HEIGHT RISES... GOOD LOW LEVEL WARM ADVECTION AND ABUNDANT SUNSHINE SHOULD COMBINE TO BRING ABOUT A NICE BOOST IN TEMPS ON SUNDAY... WITH HIGHS MOSTLY IN THE UPPER 60S TO LOWER 70S ON GUSTY S/SE WINDS. SUN NGT THROUGH MON WILL BRING THE FIRST OF SEVERAL RAIN CHANCES THROUGHOUT THE EXTENDED... AS 30+ KT LOW LEVEL JET AND ATTENDANT MOISTURE TRANSPORT AND CONVERGENCE AIMED OVER THE REGION BY LATE SUN EVE INTO MON AM AHEAD OF AN UPPER LEVEL DISTURBANCE LIFTING OUT OF THE CENTRAL PLAINS. ISOLD/SCTD ELEVATED STORMS SEEM REASONABLE WITH BOTH NAM AND GFS MODELS ADVECTING STEEP PLUME OF MID LEVEL LAPSE RATES IN EXCESS OF 7 C/KM IN 700-500 MB LAYER BY 12Z MON. IN ADDITION... CANT RULE OUT SEEING SOME FOG AND DRIZZLE WITH SUCH STRONG LOW LEVEL MOISTURE TRANSPORT WITH SFC DEWPTS CLIMBING THROUGH THE 50S INTO 60S. ALSO... EXPECTING NON DIURNAL TEMP TREND WITH TEMPS STEADY TO RISING OVRNGT SUN NGT. RAIN CHANCES WILL PERSIST MON NGT INTO TUE WITH SUGGESTIONS OF ADDITIONAL UPPER LEVEL ENERGY LIFTING OUT OF THE PLAINS AHEAD OF WESTERN CONUS TROUGH. OUR REGION WILL CONTINUE TO RESIDE IN SOUTHWESTERLY FLOW ALOFT THROUGH AT LEAST MIDWEEK WITH BROAD... DEEP TROUGH CENTERED OFF THE PACIFIC NORTHWEST COAST. THIS WILL RESULT IN CONTINUATION OF ABOVE TO MUCH ABOVE NORMAL TEMPS WHILE STAYING UNSETTLED... ALTHOUGH SUGGESTION OF LOWER RISK OF PCPN TUE INTO WED WITH MAIN FRONTAL ZONE LOCATED TO OUR NORTH/WEST. ANTICIPATE FLOW PATTERN ALOFT TO FLATTEN OR TRANSITION TO SEMI-ZONAL LATE WEEK AS MORE SUBSTANTIAL ENERGY EJECTS FROM WESTERN TROUGH. THIS WILL SEND THE BOUNDARY BACK THROUGH AS COLD FRONT ACCOMPANIED BY SHOWERS AND STORMS WED NGT THROUGH THU BASED ON THE RECENT MODEL TRENDS OR DPROG/DT OF UKMET... ECMWF AND GFS. MOST AREAS LIKELY TO SEE 0.25 TO 0.75 INCH OF RAIN WITH AREAS OF 1+ INCHES BETWEEN THE TWO MAIN PCPN WINDOWS OF SUN NGT-MON NGT AND WED NGT- THU NGT. MCCLURE && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS JACKSON KY
346 AM EDT SAT OCT 20 2012 .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 346 AM EDT SAT OCT 20 2012 CURRENT CONDITIONS ACROSS EASTERN KENTUCKY FEATURE AN UPPER LEVEL LOW CENTERED OVER MI KEEPING CONTINUED CLOUD COVER OVER THE OHIO VALLEY. THEREFORE...THIS WILL KEEP MORNING TEMPERATURES WARM IN THE MID 40S. WITH THE HEATING OF DAY AND AT LEAST A TAD OF INSTABILITY AND THE UPPER LEVEL LOW PROVIDING SEVERAL WEAK VORT MAXES MOVING THROUGH...WILL KEEP ISOLATED SPRINKLES ACROSS THE AREA THROUGH THE AFTERNOON...MAINLY ALONG AND NORTH OF THE MOUNTAIN PARKWAY. GIVEN THE CURRENT TREND OF THE MODELS...WILL LEAN TOWARD A SLOWER EXIT OF THE UPPER LOW TO THE NORTHEAST. THEREFORE...KEEPING HIGH TEMPS FOR TODAY TEMPERED TO THE UPPER 50S. LOCALES SUCH AS BLACK MOUNTAIN WILL STRUGGLE TO REACH THE MID 40S. HEADING INTO TONIGHT...THE FORECAST CHALLENGE ARISES...AS THE NAM AND RUC HINT AT THE UPPER LOW AND ASSOCIATED 850 MOISTURE/CLOUD COVER FINALLY EXITING TO THE NORTHEAST. THIS PROCESS CONTINUING THROUGH TONIGHT WILL SLOWLY ALLOW CLEARING FROM THE SOUTHWEST TO THE NORTHEAST. SO HAVE TRIED TO SHOW THIS IN THE SUN NIGHT MIN TEMPS AS STATIONS SUCH AS MONTICELLO COULD BOTTOM OUT INTO THE MID 30S TONIGHT. SO WENT WITH A SIGNIFICANT RIDGE VALLEY SPLIT WHERE AREAS WILL CLEAR OUT ALONG WITH A GENERAL GRADIENT WITH THE SOUTHWEST BEING COOLER TO THE NORTHEAST BEING WARMER AS THE CLOUD COVER EXITS. THIS WILL ALSO ALLOW FOR SOME EXTENSIVE FOG DEVELOPMENT TONIGHT ESPECIALLY WHERE AREAS CLEAR OUT. THE COLDEST LOCATIONS WILL ALSO SEE SOME PATCHY FROST. FOR SUNDAY...CLOUD COVER IS EXPECT TO CLEAR OUT WITH A SHORTWAVE RIDGE OVERHEAD AND AN OVERALL GREAT WEATHER DAY WITH LIGHT SOUTHERLY WINDS. HEATING TO START THE DAY WILL BE HINDERED AT FIRST AS MORNING FOG WILL BE SLOW TO BURN OFF. HEADING INTO THE COLDER MONTHS MORNING FOG WILL TAKE A BIT LATER TO CLEAR OUT. BUT SUNDAYS HIGHS WILL QUICKLY WARM INTO THE UPPER 60S AND AROUND 70 IN SOUTHERLY FLOW. SO A PLEASANT AND DRY FORECAST IS ON TAP BY SUNDAY. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 346 AM EDT SAT OCT 20 2012 AT THE START OF THE PERIOD...A TROUGH IS EXPECTED TO BE DEPARTING THE NORTHEASTERN US WITH RIDGING EXTENDING FROM MEXICO NORTH INTO THE WESTERN GULF AND MUCH OF THE SOUTHEASTERN US AND MS VALLEY TO LOWER OH VALLEY REGIONS. MEANWHILE A TROUGH IS EXPECTED TO BE DIGGING OFF THE NORTHWEST COAST. A COUPLE OF SHORTWAVES PER MODEL CONSENSUS ARE EXPECTED TO BE WORKING AROUND THE SOUTHEASTERN RIDGING...ONE MOVING THROUGH THE PLAINS AND APPROACHING THE MID MS VALLEY REGION AT THE START OF THE PERIOD WITH ANOTHER WORKING FROM THE DESERT SOUTHWEST TOWARD THE SOUTHERN PLAINS. THROUGH MONDAY NIGHT AND TUESDAY...HEIGHTS WILL RISE ALONG THE EASTERN SEABOARD AS THE TROUGH DEPARTS THE NORTHEASTERN US WITH RIDGING EXTENDING FROM MEXICO ACROSS THE GULF AND INTO THE SOUTHEASTERN STATES AROUND 12Z TUE PER MODEL CONSENSUS. THE FIRST OF THE SHORTWAVES MENTIONED PREVIOUSLY IS PROGGED TO PASS WELL TO OUR NW AND THEN NORTH AS IT MOVES IT AROUND THE RIDGING FROM SUN NIGHT INTO MONDAY. FAIRLY CLOSE ON ITS HEELS WILL BE THE NEXT SHORTWAVE WORKING ACROSS THE PLAINS AND TOWARD THE MID MS VALLEY REGION AND THEN NORTH OF THE AREA ON TUE. BOTH OF THESE SHOULD BRING JUST SOME HIGH AND MID CLOUDS FOR THE MOST PART...WITH ANY PRECIP CHANCES WELL WEST AND NORTH OF THE REGION. RIDING SHOULD THEN REASSERT ITSELF AT MIDWEEK OVER THE WESTERN GULF AND INTO THE SOUTHEASTERN US...WITH A RATHER BROAD TROUGH OVER THE WESTERN US AND EAST INTO THE PLAINS. A SHORTWAVE TROUGH ASSOCIATED WITH THIS BROAD THROUGH SHOULD GRADUALLY EJECT NORTHEAST TOWARD THE GREAT LAKES ON THU INTO THU NIGHT WITH RATHER ZONAL FLOW LEFT IN PLACE AT MIDWEEK. THERE ARE TIMING DIFFERENCES WITH THIS LAST SHORTWAVE AND THE EVOLUTION/STRENGTH OF A CLOSED LOW OVER THE GREAT LAKES/ONTARIO AREA AT THE END OF THE WEEK. HOWEVER...YET ANOTHER IN A SERIES OF SFC LOWS TRACKING ACROSS THE PLAINS AND INTO THE GREAT LAKES REGION IS ANTICIPATED WITH THE TRAILING RATHER SHEARED OUT BOUNDARY WORKING INTO THE REGION LATE IN THE PERIOD. THE ECMWF RUNS HAVE BEEN FASTER WITH THIS BOUNDARY OVER THE PAST FEW RUNS COMPARED TO THE GFS RUN. SFC RIDGING SHIFTING EAST INITIALLY IN THE PERIOD ALONG WITH SOME SUBSIDENCE ASSOCIATED WITH HEIGHT RISES SHOULD BE FAVORABLE FOR RIVER VALLEY FOG ON SUN NIGHT AND A RIDGE/VALLEY TEMP SPLIT. MANY OF THE VALLEY LOCATIONS...ESPECIALLY EAST SHOULD REACH THE UPPER 30S TO LOW 40S ON SUN NIGHT. TEMPERATURES WILL CONTINUE TO MODERATE ASSOCIATED WITH THE RISING HEIGHTS AND SOUTHERLY FLOW ON MON. THE MODEL CONSENSUS IS CURRENTLY BELOW THE MEX NUMBERS...BUT NUDGED TEMPS A DEGREE ABOVE THE MODEL CONSENSUS FOR MON. MIN T SHOULD MODERATE ON MON NIGHT AS WELL...THOUGH A RIDGE/VALLEY SPLIT IS STILL EXPECTED OVER THE SOUTHEASTERN COUNTIES WITH A SIMILAR MAGNITUDE AS SUN NIGHT. MIN T ON TUE NIGHT SHOULD BE A COLDER ON AVERAGE COMPARED TO MON NIGHT WITH THE RIDGE STARTING TO REASSERT ITSELF AND A BIT LESS CLOUD COVER ON AVERAGE WITH YET ANOTHER IN A SERIES OF RIDGE/VALLEY TEMP SPLITS. WED NIGHT SHOULD ALSO FAVOR A RIDGE/VALLEY TEMP SPLIT...BUT THU NIGHT SHOULD FEATURE A MINIMAL OR NO RIDGE/VALLEY TEMP SPLIT AS THE GRADIENT INCREASES AHEAD OF AN APPROACHING COLD FRONT. SOME TERRAIN ADJUSTMENTS WERE MADE TO THE GRID LOAD FOR MIN T FROM MON NIGHT THROUGH WED NIGHT TO REFLECT THE ABOVE MENTIONED RIDGE/VALLEY TEMP SPLITS. MAX TEMPS WILL MODERATE FURTHER INTO MIDWEEK AND REMAIN ABOVE NORMAL THROUGH THE END OF THE PERIOD. MAX TEMPS SHOULD NEAR 15 DEGREES ABOVE NORMAL ON WED AS 850 MB TEMPS REACH ABOUT THE 12 TO 15C RANGE. WED IS EXPECTED TO BE THE WARMEST DAY. DURING THE PAST COUPLE OF WARMER DAYS THE MEX HAS BEEN TOO WARM WITH MAX T AND THE GRID LOAD TEMPS IN THE UPPER 70S WERE ACCEPTED. THE ONLY POPS IN THE PERIOD WILL COME AT THE END OF THE PERIOD. IF THE FASTER ECMWF IS RIGHT OR MODELS TREND TOWARD IT...THEN POPS MAY NEED TO BE INCREASED ON THU NIGHT. HOWEVER...THE MODEL CONSENSUS GRID LOAD FAVORED POPS MAINLY ON FRI...AND THIS SEEMED TO BE A REASONABLE COMPROMISE GIVEN THE MODEL DIFFERENCES NOTED ABOVE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 142 AM EDT SAT OCT 20 2012 WITH PERSISTENT CLOUD COVER OVER THE AREA AT AROUND 4 TO 5 KFT...NOT EXPECTING MUCH FOG DEVELOPMENT TONIGHT. LOCATIONS SUCH AS JKL HAVE SEEN SOME RAINFALL TODAY WILL SEE A LOWERING OF THE CEILINGS AND A MVFR CEILING WILL DEVELOP AT JKL BY 10Z AND WILL LIFT BY 13Z. WILL EXPECT A 4 KFT LAYER TO BE PERSISTENT THROUGH THE DAY TOMORROW WITH A 5 TO 10 KNOT WEST WINDS BEFORE DECOUPLING BY 23Z. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...SHALLENBERGER LONG TERM....JP AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS RALEIGH NC
230 AM EDT SAT OCT 20 2012 .SYNOPSIS... DRY HIGH PRESSURE WILL BUILD INTO THE CAROLINAS FROM THE WEST OVER THE WEEKEND AND PERSIST THROUGH THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH SATURDAY NIGHT/... AS OF 1005 PM FRIDAY... THE LEAD LOW LEVEL FRONTAL ZONE HAD MOVED JUST EAST OF THE NC OUTER BANKS AT 02Z...WHILE A REINFORCING COLD FRONT HAD MOVED TO THE VICINITY OF THE BLUE RIDGE. THIS TRAILING/REINFORCING COLD FRONT WILL PRODUCE A BRIEF PERIOD OF LOW LEVEL CAA IN THE WEST TOWARD DAYBREAK...THEN FOR A FEW HOURS SHORTLY THEREAFTER ACROSS THE REMAINDER OF CENTRAL NC. OTHERWISE...THE NIGHT WILL BE CLEAR WITH ALTERNATING PERIODS OF CALM AND SOUTHWESTERLY STIRRING IN ADVANCE OF THE TRAILING FRONT...WHICH WILL RESULT IN CONTINUED WIDE-RANGING AND VARIABLE TEMPERATURES -- HIGHLIGHTED AT 02Z BY 45 DEGREES AT K5W8 AND A PAIR OF 60S AT KINT AND KFAY -- OVERNIGHT. PROVIDED EVERYONE HAS AT LEAST A BRIEF PERIOD OF CALM AS EXPECTED...LOWS WILL BOTTOM IN THE 41 TO 48 DEGREE RANGE. -MWS AS OF 220 PM FRIDAY... THE COLD FRONT EXTENDING SOUTH FROM THE OCCLUDED LOW OVER THE GREAT LAKES HAS BEEN MOVING VERY SLOWLY ACROSS THE CWA TODAY...STRUGGLING TO GET PAST US HWY 1 THROUGH NOON. HOWEVER...DEWPOINTS ARE FINALLY BEGINNING TO MIX OUT MORE EFFICIENTLY BEHIND THE FRONT...AND THE SHARP DEWPOINT/INSTABILITY GRADIENT IS SHIFTING EAST INTO THE COASTAL PLAIN. DRIER AIR ALOFT NOTED IN WATER VAPOR IMAGERY IS LIMITING CUMULUS DEVELOPMENT TO A NARROW STRIP ALONG A REGION CONFLUENCE FROM LEXINGTON TO ROXBORO. HRRR RUNS HAVE BEEN SHOWING A FEW ISOLATED SHOWERS OVER THE NORTHERN PIEDMONT AFTER 20Z...BUT THIS SEEMS OVERDONE GIVEN THE AMOUNT OF DRY AIR ALOFT. OTHERWISE...SOUTHWESTERLY WIND GUSTS ARE STARTING TO DEVELOP...MOSTLY IN THE TEENS THUS FAR...BUT A FEW MAY REACH 20-25KT BEFORE SUNSET. TONIGHT... A SHORTWAVE IN THE BASE OF THE UPPER TROUGH WILL SWING ACROSS GA/SC...WITH CONTINUED DRY CONDITIONS AND MOSTLY CLEAR SKIES ACROSS CENTRAL NC. A LIGHT WESTERLY WIND MAY LIMIT FULL RADIATIONAL COOLING...MID TO UPPER 40S WEST TO EAST. SATURDAY AND SATURDAY NIGHT... BROAD CYCLONIC UPPER LEVEL FLOW WILL CONTINUE OVER THE AREA AS THE GREAT LAKES UPPER LOW BEGINS TO OPEN UP AND LIFT NORTHEAST. A SPEED MAX DIVING THROUGH THE BACK SIDE OF THE UPPER TROUGH WILL SHARPEN THE TROUGH AXIS AS IT CROSSES THE AREA SATURDAY EVENING. THE ADDED DPVA MAY BE ENOUGH TO HELP ENHANCE SOME LATE AFTERNOON CLOUD COVER AS RH CROSS SECTIONS SHOW A LAYER OF MOISTURE AT THE TOP OF THE BOUNDARY LAYER (5-8KT FT). WITH WEAK THERMAL ADVECTION/FLOW AHEAD OF THE TROUGH AXIS...WILL USE 1000-850MB THICKNESSES FOR HIGHS...YIELDING UPPER 60S TO LOWER 70S. ONCE THE TROUGH AXIS MOVES EAST...NORTHWESTERLY FLOW WILL DEVELOP ALOFT SATURDAY NIGHT. THIS TYPE OF PATTERN SUGGESTS THE POTENTIAL FOR OROGRAPHIC CIRRUS...ALTHOUGH THE NAM/GFS SHOW THE BEST UPPER LEVEL MOISTURE DIVING JUST SOUTH OF THE APPALACHIANS. WITHOUT CIRRUS...THE ARRIVAL OF BETTER LOW LEVEL COLD ADVECTION BEHIND THE TROUGH AXIS SHOULD LEAD TO LOWS IN THE LOW TO MID 40S. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 230 PM FRIDAY... CLOSED UPPER LOW AND ASSOCIATED UPPER TROUGH OVER THE EASTERN US WILL LIFT NORTHEASTWARD INTO SOUTHEASTERN CANADA DURING THE DAY ON SUNDAY...WITH STRONG SYNOPTIC SCALE SUBSIDENCE SETTLING OVER THE REGION IN IT WAKE AS THE UPSTREAM RIDGE OVER THE CENTRAL US SHIFTS EASTWARD INTO THE AREA. THIS WILL RESULT IN CONTINUED DRY CONDITIONS WITH A RAPID WARM-UP/MODERATION FROM BELOW NORMAL DAYTIME TEMPERATURES IN THE MID TO UPPER 60S ON SUNDAY TO ABOVE NORMAL READINGS IN THE LOWER TO MID 70S BY MONDAY. STRONG RADIATIONAL COOLING AND A DRY AIRMASS IN PLACE WILL STILL ALLOW FOR CHILLY MORNING LOWS BOTH MORNINGS. LOWS IN THE LOWER TO MID 40S. & .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 230 PM FRIDAY... BROAD SUBTROPICAL RIDGING WILL ENVELOP THE SOUTHEASTERN/EASTERN US THROUGH THE UPCOMING WORK WEEK...DOWNSTREAM OF THE WESTERN/CENTRAL US TROUGH. WHILE THERE ARE SOME GROSS DIFFERENCES WITH HOW NWP MODELS HANDLE THE EVOLUTION OF THE WESTERN US TROUGH AND ASSOCIATED REX BLOCK...CENTRAL NC LOOKS TO BE WELL UNDER THE INFLUENCE OF THE SUBTROPICAL RIDGE TO CLOSE THE WORK WEEK...KEEPING SHORTWAVE DISTURBANCES AT ARMS LENGTH...TRACKING NORTHEAST THROUGH THE PLAINS...THROUGH THE THE GREAT LAKES AND THEN INTO SOUTHEASTERN CANADA. THIS WILL RESULT IN WARM AND QUITE WEATHER CONDITIONS("INDIAN SUMMER")THROUGH THE WEEK. DAYTIME HIGHS WELL IN THE MID TO UPPER 70S. LOWS IN THE UPPER 40S TO LOWER 50S. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 200 AM SATURDAY... 24-HR TAF PERIOD: VFR CONDITIONS WILL RULE THROUGH THE TAF PERIOD IN ASSOC/W A DRY AIRMASS IN PLACE IN THE WAKE OF A RECENT COLD FRONTAL PASSAGE. ASIDE FROM SCATTERED DIURNAL CU AT 5-6 KFT AGL AT THE INT/GSO TAF SITES THIS AFTERNOON...CLEAR SKIES WILL PREVAIL. LIGHT/VARIABLE WINDS AT ~5 KT WILL BECOME WESTERLY AT 5-10 KT THIS AFTERNOON...THEN NORTHWEST AT ~5 KT AFTER SUNSET. LOOKING AHEAD: SURFACE HIGH PRESSURE ANCHORED OVER THE CAROLINAS WILL RESULT IN DRY/VFR CONDITIONS THROUGH EARLY TO MID NEXT WEEK. -VINCENT && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...MWS/BLS SHORT TERM...CBL LONG TERM...CBL AVIATION...VINCENT
AREA FORECAST DISCUSSION
NWS BISMARCK ND
331 AM CDT SAT OCT 20 2012 .SHORT TERM...TODAY THROUGH SUNDAY... LATEST WATER VAPOR IMAGERY SATELLITE IMAGERY SHOWS MID/HIGH LEVEL CLOUDS STREAMING THROUGH MONTANA INTO NORTH DAKOTA AS A STRONG H3 120KT JET PUNCHES INTO CENTRAL/NORTHERN IDAHO THIS MORNING. AT THE SURFACE...A WARM FRONT WAS OBSERVED MOVING THROUGH WESTERN AND CENTRAL NORTH DAKOTA AND THIS WILL CONTINUE TO PROGRESS EAST DURING THE MORNING. LATEST REGIONAL RADAR SHOWS SOME ENHANCEMENT TO ECHOES IN EAST CENTRAL MONTANA. THE 00Z GFS WAS FIRST TO LATCH ONTO THIS...AND NOW WITH DEVELOPMENT UNDERWAY...THE 06Z NAM AND LATEST RUC SPILL SOME MINOR QPF INTO OUR WESTERN ZONES AROUND 15Z. HAVE ADDED IN A SLIGHT CHC FOR THE MORNING HOURS. OTHERWISE WESTERN AND CENTRAL NORTH DAKOTA REMAIN IN THE WARM SECTOR TODAY WITH HIGHS RANGING BETWEEN 65F AND 75F. WINDS WILL BE STRONGEST ACROSS THE NORTHWEST INTO NORTH CENTRAL NORTH DAKOTA WHERE THE NAM/GFS BUFKIT SOUNDINGS SHOW MIXED LAYER WINDS IN THE 20KT TO 25KT RANGE. BEST FORCING/LIFT THIS AFTERNOON REMAINS IN SOUTHERN CANADA TODAY...HOWEVER CONSENSUS AMONG THE MODELS IS THAT A SLIGHT CHC FOR A RAINSHOWER IN THE WEST AND NORTH CENTRAL IS POSSIBLE DURING THE AFTERNOON. HOWEVER THE BETTER CHANCE FOR RAIN SHOWERS ARRIVES TONIGHT ALONG AND AHEAD OF A COLD FRONT. MUCH COOLER BEHIND THE COLD FRONT LATE SATURDAY NIGHT INTO SUNDAY WITH HIGHS COMING BACK TO NORMAL FOR THIS TIME OF YEAR...EXPECT HIGH TEMPERATURES IN THE LOW TO MID 50S ACROSS WESTERN AND CENTRAL NORTH DAKOTA. ANY SHOWERS WOULD BE CONFINED TO THE FAR SOUTHWEST. .LONG TERM...SUNDAY NIGHT THROUGH FRIDAY. PRECIPITATION CHANCES THROUGH MUCH OF THE PERIOD WILL BE THE MAIN FORECAST CONCERN. THE START OF THE LONG TERM PERIOD WILL FEATURE A LARGE H5 VORTEX OFF THE COAST OF THE PACIFIC NORTHWEST...WITH SOUTHWESTERLY FLOW ACROSS THE NORTHERN PLAINS. THE H5 LOW WILL SEND OCCASIONAL WAVES TOWARDS NORTH DAKOTA ON THE SOUTHWESTERLY FLOW WHICH WILL BRING OFF AND ON PRECIPITATION CHANCES TO THE FORECAST AREA. ONE OF THE HIGHER CHANCES OF PRECIPITATION APPEARS TO COME MONDAY NIGHT AS A FAIRLY STRONG H7 WAVE MOVES ACROSS THE NORTHERN PLAINS. MODEL GENERATED VERTICAL MOTION INCREASES IN THE H85-7 LAYER WITH THE BEST SATURATION IN PARTS OF WESTERN AND NORTHERN NORTH DAKOTA. WILL CARRY 50 POPS ACROSS THE NORTH...WITH LESSER CHANCES IN THE 20-30 PERCENT RANGE IN THE SOUTHEAST FOR MONDAY NIGHT. FORECAST SOUNDINGS SUGGEST A RAIN/SNOW MIX IS POSSIBLE MONDAY NIGHT INTO TUESDAY MORNING ESPECIALLY IN THE NORTHWEST. THE LARGER SCALE TROUGH ACROSS THE WESTERN CONUS EVENTUALLY MOVES EAST TOWARDS THE MIDDLE OF NEXT WEEK...THOUGH THE VARIOUS DETERMINISTIC MODEL RUNS STILL SHOW DIFFERENCES IN HOW THEY HANDLE ITS PROGRESSION. FOR NOW WILL GO WITH MORE OF A ENSEMBLE/BLENDED MODEL APPROACH WHICH KEEPS A CHANCE OF PRECIPITATION THROUGH THE REST OF THE EXTENDED FORECAST PERIOD. WILL GENERALLY CARRY RAIN DURING THE DAY TIME HOURS...WITH RAIN/SNOW AT NIGHT INTO THE EARLY MORNINGS. LOOKING AT TEMPERATURES...A GENERAL COOLING TREND IS EXPECTED THROUGH THE PERIOD WITH HIGHS MONDAY IN THE MID 40S TO MID 50S...FALLING INTO THE 30S TO LOWER 40S BY FRIDAY. && .AVIATION...THE LOW CLOUDS HAVE EXITED KJMS...HOWEVER A PATCH OF LOWER CLOUDS STILL EXISTS JUST TO THE WEST OF THE TERMINAL LOCATION. WILL KEEP AN EYE ON THOSE...AND MAY STILL NEED TO ADD A PERIOD OF LOWER CLOUDS TO KJMS EARLY THIS MORNING. THE OTHER TERMINAL LOCATIONS SHOULD REMAIN VFR. THERE WILL BE OCCASIONAL MID AND HIGH LEVEL CLOUDS...HOWEVER WITH LIMITED LOW LEVEL MOISTURE...VFR WILL PREVAIL. WINDS BE LIGHT AND FROM THE SOUTH EARLY THIS MORNING...BUT THEY WILL BECOME MORE WESTERLY WITH TIME FROM WEST TO EAST AS A WEAK FRONTAL BOUNDARY CROSSES THE AREA. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...KS LONG TERM/AVIATION...CK
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
359 AM EDT SAT OCT 20 2012 .SYNOPSIS... AN UPPER LEVEL LOW PRESSURE SYSTEM ACROSS THE GREAT LAKES WILL CONTINUE TO MOVE NORTHEAST AWAY FROM THE REGION TODAY. HIGH PRESSURE WILL BUILD IN ITS WAKE TONIGHT INTO SUNDAY. THE HIGH WILL CONTINUE TO INFLUENCE THE REGION THROUGH EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AN UPPER LEVEL CLOSED LOW CENTERED OVER SRN MICHIGAN THIS MORNING WILL CONTINUE TO MOVE NORTHEAST AWAY FROM THE REGION TODAY. IN THE MEANTIME...AN EMBEDDED VORT LOBE ROTATING AROUND THE LOW WILL QUICKLY MOVE EAST ACRS THE REGION EARLY THIS MORNING. MOSAIC RADAR DEPICTED AN AREA OF SHOWERS IN ASSOCIATION WITH THIS FEATURE... WHICH WAS MOVING INTO THE WHITEWATER AND MIAMI VALLEYS. AM EXPECTING THESE SHOWERS TO HOLD TOGETHER LONG ENOUGH FOR LIKELY POPS ACRS THE WHITEWATER AND MIAMI VALLEYS (DAYTON AREA) WITH A WEAKENING TREND AS IT SHIFTS TOWARD CENTRAL OHIO BY SUNRISE PER THE HRRR MODEL. OTHERWISE...THE REMAINDER OF THE DAY WILL EXHIBIT LOW CHANCE POPS DUE TO WEAK DAYTIME INSTABILITY WITH THE THREAT OF RAIN COMING TO AN END BY THIS EVENING. MOSTLY CLOUDY SKIES WILL BEGIN TO PARTIALLY CLEAR LATE IN THE DAY. HIGHS TODAY WILL REMAIN BELOW NORMAL...PEAKING INTO THE LOWER AND MID 50S. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... SURFACE HIGH PRESSURE IS EXPECTED TO BUILD INTO THE OHIO VALLEY FROM THE SOUTHWEST TONIGHT. SKIES WILL CLEAR...AND WITH WINDS BECOMING LIGHT...SOME FROST FORMATION IS EXPECTED. PARTS OF THE AREA REMAIN IN THE FROST/FREEZE PROGRAM AND HAVE ISSUED A FROST ADVISORY FOR THESE LOCATIONS. LOWS WILL GENERALLY FALL INTO THE MID AND UPPER 30S...BUT A FEW LOWER 30S CAN NOT BE RULED OUT. SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION ON SUNDAY. WITH AMPLE SUNSHINE AND A MODIFYING AIRMASS...TEMPERATURES WILL WARM INTO THE LOWER AND MID 60S...WHICH IS ABOUT NORMAL FOR THIS TIME OF THE YEAR. FOR THE PERIOD SUNDAY NIGHT INTO MONDAY...CENTER OF THE SURFACE HIGH WILL MOVE TO A POSITION OVER THE MID ATLANTIC/SE U.S. MODELS CONTINUE TO INDICATE THAT ALTHOUGH A MID LVL RIDGE WILL BUILD ACRS THE REGION...IT WILL BE RELATIVELY FLAT IN AMPLITUDE...AND AS SUCH...WILL ALLOW FOR WEAK FEATURES TO MOVE THROUGH IT. ONE SUCH FEATURE IS EXPECTED TO BRUSH BY OUR NW MONDAY AFTERNOON INTO MONDAY EVENING. AT THIS TIME...HAVE INCREASED CLOUDS ACRS THE REGION...ESPECIALLY NORTHWEST...AND HAVE KEPT THE THREAT FOR SHOWERS JUST OUTSIDE OUR AREA. THE AIRMASS WILL CONTINUE TO WARM AND WITH A SOUTHERLY FLOW...TEMPERATURES WILL RISE INTO THE LOWER AND MID 70S. FOR MONDAY NIGHT INTO TUESDAY NIGHT...ANOTHER WEAK DISTURBANCE IS FORECAST TO MOVE THROUGH THE RIDGE. THIS FEATURE WILL COMBINE WITH SOME ISENTROPIC LIFT TO BRING A THREAT FOR A FEW SHOWERS TO OUR NWRN ZONES...PARTICULARLY MONDAY NIGHT INTO TUESDAY. OTHER LOCATIONS WILL GENERALLY SEE PARTLY CLOUDY CONDITIONS. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... MID LEVEL RIDGE WILL REBOUND ON WEDNESDAY AHEAD OF THE NEXT WEATHER SYSTEM TO AFFECT THE REGION BY THE END OF THE WEEK. ABOVE NORMAL TEMPERATURES WILL CONTINUE. A COLD FRONT WILL APPROACH AND MOVE THROUGH THE AREA THURSDAY NIGHT INTO FRIDAY. AFTER THE FRONT MOVES THROUGH HIGH TEMPERATURES ON FRIDAY WILL BE IN THE MIDDLE 60S TO AROUND 70. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... SCATTERED RAIN SHOWERS WILL CONTINUE MOVING THROUGH THE REGION TONIGHT. THE CURRENT BATCH OF SHOWERS WILL EXIT THE AREAS NEAR THE TAF SITES BY 08Z-10Z...BUT ADDITIONAL RAIN DEVELOPING OVER INDIANA WILL ALSO BE MOVING IN CLOSER TO DAYBREAK. WHILE PREVAILING VFR VISIBILITIES ARE EXPECTED IN THE MEAN TIME (WITH MVFR CEILINGS)...THE SHOWERS WILL BE CAPABLE OF PRODUCING MVFR VISIBILITIES. AS THE MOISTURE OVER INDIANA WORKS ITS WAY IN...CONDITIONS WILL DETERIORATE A BIT FURTHER NEAR DAYBREAK (12Z). CEILINGS WILL STRADDLE THE MVFR/IFR THRESHOLD...AND MVFR VISIBILITIES WILL BECOME MORE COMMON. HOWEVER...AFTER 12Z...PRECIPITATION WILL BECOME LESS LIKELY. CLOUDS MAY BE SLOW TO RISE IN THE MORNING...BUT VFR CONDITIONS ARE EXPECTED BY AFTERNOON. A FEW LIGHT SHOWERS ARE POSSIBLE IN CENTRAL OHIO (KCMH/KLCK) DURING THE PEAK HEATING HOURS OF THE AFTERNOON...BUT CONFIDENCE IN TIMING AND PLACEMENT IS LOW. .OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...FROST ADVISORY FROM 2 AM TO 9 AM EDT SUNDAY FOR OHZ046-055-061- 062-064-070-071-077>079. KY...FROST ADVISORY FROM 2 AM TO 9 AM EDT SUNDAY FOR KYZ089>099. IN...FROST ADVISORY FROM 2 AM TO 9 AM EDT SUNDAY FOR INZ073>075-080. && $$ SYNOPSIS...HICKMAN NEAR TERM...HICKMAN SHORT TERM...HICKMAN LONG TERM...HICKMAN/NOVAK AVIATION...HATZOS
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1157 PM CDT FRI OCT 19 2012 .UPDATE...FOR AVIATION. && .AVIATION... 06Z TAFS...BKN-OVC VFR CIGS ARE EXPECTED THROUGH THE NIGHT WITH LIGHT WSW WINDS. W WINDS NEAR 8KT EXPECTED SATURDAY...WITH BKN VFR CIGS GRADUALLY BECMG SCT. 13 && .PREV DISCUSSION... /ISSUED 1119 PM CDT FRI OCT 19 2012/ UPDATE... HAVE UPDATED THE SUITE OF FORECAST PRODUCTS TO DEPICT CONTINUED CLOUDINESS ACROSS NRN PORTIONS OF THE MID STATE WITH BREAKS IN CLOUD COVERAGE MOST LIKELY ACROSS SRN PORTIONS OF THE MID STATE. WITH OVERALL CLOUD COVERAGE IN MIND AND CURRENT TEMPS...HAVE ALSO RAISED LOWS BY A COUPLE OF DEGREES ACROSS THE VAST MAJORITY OF THE MID STATE...EXPECT LOCATIONS NEAR THE TN/AL BORDER WHERE BREAKS IN CLOUD COVERAGE MOST LIKELY...THUS ALLOWING FOR COOLER TEMPS. ALSO MADE AN ADJUSTMENT TO PATCHY FOG FOR SAT NIGHT INTO SUN MORNING... MENTIONING PATCHY FOG FORMATION MAINLY AFTER MIDNIGHT NEAR BODIES OF WATER AND THE ELEVATED VALLEYS OF THE PLATEAU AND EXTENDING THIS THRU THE MID MORNING HRS ON SUN. PREV DISCUSSION.../ISSUED 601 PM CDT FRI OCT 19 2012/ UPDATE... CURRENT SFC OBS AND CONSENSUS SHORT RANGE MODEL GUIDANCE...INCLUDING THE LATEST HIGH RESOLUTION RAPID REFRESH...SHOWING CLDY SKIES ACROSS THE MID STATE CONTINUING THRU AT LEAST THE MID EVENING HRS...WITH SOME DECREASE IN CLOUDINESS POSSIBLE LATE EVENING AND OVERNIGHT. HRRR MOST AGGRESSIVE IN ERODING CLOUD COVERAGE AS COMPARED TO SREF AND RUC 13KM. ACCORDINGLY... HAVE UPDATED THE SUITE OF FORECAST PRODUCTS TO REFLECT CLDY SKIES THRU THE EVENING HRS...WITH PTCLDY SKIES OVERNIGHT. ALSO MADE SOME MINOR CHANGES TO CLOUD COVERAGE ON SAT FOR A TRANSITION TO PTSUNNY SKIES ACROSS THE ENTIRE MID STATE DURING THIS TIME PERIOD. 31 PREV DISCUSSION.../ISSUED 149 PM CDT FRI OCT 19 2012/ SHORT TERM...LOW LEVEL WRAP-AROUND CLOUDS CONTINUED TO SINK SOUTHWARD ACROSS THE MID STATE EARLY THIS AFTERNOON. TEMPERATURES ACROSS THE EXTREME NORTH, WHERE SKIES HAVE BEEN OVC MUCH OF THE DAY, STALLED OUT IN THE UPPER 50S TO AROUND 60, WHILE SUNNY SOUTHERN AREAS SAW TEMPS PUSH TO AROUND 70 BY 1 PM. THE LIGHT RAIN AND SPRINKLES HAVE, SO FAR, REMAINED MOSTLY NORTH OF THE BORDER (UP ACROSS KY). BELIEVE LOW LEVEL MOISTURE WILL CONTINUE TO ROTATE AROUND BASE OF GREAT LAKES AND OHIO VALLEY TROUGH THROUGH SATURDAY, PROVIDING VARIABLE CLOUDINESS ACROSS OUR NORTHERN COUNTIES. THIS WILL PRODUCE A TEMP GRADIENT MUCH LIKE TODAY`S, WITH HIGHS TOMORROW RANGING FROM THE UPPER 50S AND LOWER 60S NORTH AND PLATEAU, TO AROUND 70 OVER THE SOUTH. CLOUDS FINALLY DISSIPATE BY SATURDAY NIGHT AND AN UPPER LEVEL RIDGE BUILDS IN ACROSS THE TENNESSEE VALLEY FOR SUNDAY AND MONDAY. A WEAKENING SHORTWAVE IS FORECAST TO MOVE OUT OF THE MID- MISSISSIPPI VALLEY ACROSS THE OHIO RIVER VALLEY ON TUESDAY. HOWEVER, MAINLY JUST HIGH CLOUDS ARE EXPECTED TO SWEEP ACROSS THE MID STATE AND KEEP OUR DRY WEATHER IN PLACE. RIDGE BUILDS BACK IN AFTER WEAK SHORTWAVE PASSES TO OUR NORTHWEST ON TUESDAY AND, ASIDE FROM SOME HIGH CLOUDS STREAMING IN ON SOUTHWEST FLOW, DRY WEATHER PERSISTS AT LEAST INTO THE MIDDLE OF NEXT WEEK. LONG TERM...LATEST GFS SWEEPS A COLD FRONT ACROSS OUR AREA LATE NEXT WEEK, ALONG WITH A CHANCE FOR SHOWERS AND THUNDERSTORMS. HOWEVER, PREVIOUS ECMWF KEPT TENNESSEE VALLEY MORE UNDER THE INFLUENCE OF HIGH PRESSURE AND DRY WEATHER INTO LATE NEXT WEEK. UNLESS NEW ECMWF COMES IN WITH A MORE SOLID TREND TOWARD THE GFS, WILL PROBABLY KEEP A DRY FORECAST RUNNING THROUGH THE EXTENDED PERIOD. && .OHX WATCHES/WARNINGS/ADVISORIES...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS NASHVILLE TN
1119 PM CDT FRI OCT 19 2012 .UPDATE... HAVE UPDATED THE SUITE OF FORECAST PRODUCTS TO DEPICT CONTINUED CLOUDINESS ACROSS NRN PORTIONS OF THE MID STATE WITH BREAKS IN CLOUD COVERAGE MOST LIKELY ACROSS SRN PORTIONS OF THE MID STATE. WITH OVERALL CLOUD COVERAGE IN MIND AND CURRENT TEMPS...HAVE ALSO RAISED LOWS BY A COUPLE OF DEGREES ACROSS THE VAST MAJORITY OF THE MID STATE...EXPECT LOCATIONS NEAR THE TN/AL BORDER WHERE BREAKS IN CLOUD COVERAGE MOST LIKELY...THUS ALLOWING FOR COOLER TEMPS. ALSO MADE AN ADJUSTMENT TO PATCHY FOG FOR SAT NIGHT INTO SUN MORNING... MENTIONING PATCHY FOG FORMATION MAINLY AFTER MIDNIGHT NEAR BODIES OF WATER AND THE ELEVATED VALLEYS OF THE PLATEAU AND EXTENDING THIS THRU THE MID MORNING HRS ON SUN. && .PREV DISCUSSION.../ISSUED 640 PM CDT FRI OCT 19 2012/ UPDATE...FOR AVIATION. AVIATION... BKN-OVC VFR CIGS ARE EXPECTED THROUGH THE NIGHT WITH DIMINISHING WSW WINDS. W WINDS WILL PICK UP NEAR 10KT SATURDAY...WITH BKN VFR CIGS GRADUALLY BECMG SCT. 13 PREV DISCUSSION.../ISSUED 601 PM CDT FRI OCT 19 2012/ UPDATE... CURRENT SFC OBS AND CONSENSUS SHORT RANGE MODEL GUIDANCE...INCLUDING THE LATEST HIGH RESOLUTION RAPID REFRESH...SHOWING CLDY SKIES ACROSS THE MID STATE CONTINUING THRU AT LEAST THE MID EVENING HRS...WITH SOME DECREASE IN CLOUDINESS POSSIBLE LATE EVENING AND OVERNIGHT. HRRR MOST AGGRESSIVE IN ERODING CLOUD COVERAGE AS COMPARED TO SREF AND RUC 13KM. ACCORDINGLY... HAVE UPDATED THE SUITE OF FORECAST PRODUCTS TO REFLECT CLDY SKIES THRU THE EVENING HRS...WITH PTCLDY SKIES OVERNIGHT. ALSO MADE SOME MINOR CHANGES TO CLOUD COVERAGE ON SAT FOR A TRANSITION TO PTSUNNY SKIES ACROSS THE ENTIRE MID STATE DURING THIS TIME PERIOD. 31 PREV DISCUSSION.../ISSUED 149 PM CDT FRI OCT 19 2012/ SHORT TERM...LOW LEVEL WRAP-AROUND CLOUDS CONTINUED TO SINK SOUTHWARD ACROSS THE MID STATE EARLY THIS AFTERNOON. TEMPERATURES ACROSS THE EXTREME NORTH, WHERE SKIES HAVE BEEN OVC MUCH OF THE DAY, STALLED OUT IN THE UPPER 50S TO AROUND 60, WHILE SUNNY SOUTHERN AREAS SAW TEMPS PUSH TO AROUND 70 BY 1 PM. THE LIGHT RAIN AND SPRINKLES HAVE, SO FAR, REMAINED MOSTLY NORTH OF THE BORDER (UP ACROSS KY). BELIEVE LOW LEVEL MOISTURE WILL CONTINUE TO ROTATE AROUND BASE OF GREAT LAKES AND OHIO VALLEY TROUGH THROUGH SATURDAY, PROVIDING VARIABLE CLOUDINESS ACROSS OUR NORTHERN COUNTIES. THIS WILL PRODUCE A TEMP GRADIENT MUCH LIKE TODAY`S, WITH HIGHS TOMORROW RANGING FROM THE UPPER 50S AND LOWER 60S NORTH AND PLATEAU, TO AROUND 70 OVER THE SOUTH. CLOUDS FINALLY DISSIPATE BY SATURDAY NIGHT AND AN UPPER LEVEL RIDGE BUILDS IN ACROSS THE TENNESSEE VALLEY FOR SUNDAY AND MONDAY. A WEAKENING SHORTWAVE IS FORECAST TO MOVE OUT OF THE MID- MISSISSIPPI VALLEY ACROSS THE OHIO RIVER VALLEY ON TUESDAY. HOWEVER, MAINLY JUST HIGH CLOUDS ARE EXPECTED TO SWEEP ACROSS THE MID STATE AND KEEP OUR DRY WEATHER IN PLACE. RIDGE BUILDS BACK IN AFTER WEAK SHORTWAVE PASSES TO OUR NORTHWEST ON TUESDAY AND, ASIDE FROM SOME HIGH CLOUDS STREAMING IN ON SOUTHWEST FLOW, DRY WEATHER PERSISTS AT LEAST INTO THE MIDDLE OF NEXT WEEK. LONG TERM...LATEST GFS SWEEPS A COLD FRONT ACROSS OUR AREA LATE NEXT WEEK, ALONG WITH A CHANCE FOR SHOWERS AND THUNDERSTORMS. HOWEVER, PREVIOUS ECMWF KEPT TENNESSEE VALLEY MORE UNDER THE INFLUENCE OF HIGH PRESSURE AND DRY WEATHER INTO LATE NEXT WEEK. UNLESS NEW ECMWF COMES IN WITH A MORE SOLID TREND TOWARD THE GFS, WILL PROBABLY KEEP A DRY FORECAST RUNNING THROUGH THE EXTENDED PERIOD. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 31
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
334 AM CDT SAT OCT 20 2012 .SHORT TERM... TEMPS ARE RUNNING 10-15 DEGREES WARMER THAN THEY WERE 24 HOURS AGO AND THIS TREND WILL CONTINUE THROUGHOUT THE DAY. A STRONG H250 JET MOVING ACROSS THE PACNW AND NORTHERN ROCKIES WILL PROPAGATE INTO THE NORTHERN PLAINS LATER TODAY. THE RIGHT EXIT REGION OF THIS JET...IN CONJUNCTION WITH ENHANCED DPVA CONCOMITANT WITH THE ASSOCIATED SHORTWAVE TROF...WILL PROMOTE LEE CYCLOGENESIS THROUGHOUT THE SHORT TERM. THE EFFECT WILL BE GUSTY SOUTH TO SOUTHWEST WINDS TODAY AND A STRONG LOW LEVEL JET OVERNIGHT. BOTH THE NAM/GFS BUFR SOUNDINGS INDICATE H800 TEMPS NEAR 19C...WHICH IS ABOUT 5 DEGREES WARMER THAN WHAT WE SAW YESTERDAY /PER RAP SOUNDINGS/. GIVEN IDENTICAL MIXING AND INSOLATION...THAT WOULD TRANSLATE TO SURFACE TEMPS BEING 9F WARMER THAN ON FRIDAY. A SLIGHT INCREASE IN HIGH CLOUD COVER MAY BE ABLE TO OFFSET THE ENHANCED COMPRESSIONAL HEATING FROM THE SOUTHWEST WINDS TO KEEP TEMPS FROM WARMING FURTHER. THE RECORD HIGH TODAY FOR BOTH ABILENE AND SAN ANGELO IS 93 DEGREES. I DO NOT THINK WE WILL GET THERE BUT SAN ANGELO MAY GET CLOSE. A SIGNIFICANT INCREASE IN LOW LEVEL MOISTURE TODAY WILL CARRY OVER INTO THE OVERNIGHT HOURS AND WILL KEEP TEMPS FROM COOLING AS QUICKLY AS IN PAST DAYS. MOS FORECAST TEMPS FOR ABILENE/SAN ANGELO INDICATE OVERNIGHT LOWS IN THE VICINITY OF THE RECORD HIGH MINIMUMS /UPPER 60S/. MY GUT SAYS WE WILL COOL JUST BELOW THE MOS VALUES BUT LOWS IN THE 64-67 DEGREE RANGE SHOULD BE COMMON. WINDS ARE EXPECTED TO GUST AS WE APPROACH MIDNIGHT ALONG I-20 AND THE CONCHO VALLEY AS THE LOW LEVEL JET INTENSIFIES. FINALLY...LOW CLOUDS ARE EXPECTED TO DEVELOP OVER THE HILL COUNTRY AND SPREAD NORTH OVERNIGHT...POTENTIALLY REACHING AS FAR NORTH AS I-20. NO RAIN IS EXPECTED IN THE NEXT 24 HOURS. JOHNSON .LONG TERM... CUT OFF UPPER LOW OFF THE WEST COAST OF BAJA CALIFORNIA EXPECTED TO MOVE EAST THIS WEEKEND. NAM...GFS...AND EC MODELS SHOW FAIRLY GOOD CONSENSUS...BRINGING LIFT AHEAD OF THE LOW AFTER 1 AM MONDAY...WITH THE BEST LIFT AND SHOWER AND THUNDERSTORM CHANCES DAYBREAK THROUGH NOON MONDAY. BIG COUNTRY AND NORTHERN CONCHO VALLEY INDICATED TO HAVE THE BEST POTENTIAL RAIN. COULD SEE A FEW STRONG ELEVATED STORMS DEVELOP WITH 0-6 KM BULK SHEARS OF 35 KTS AND MUCAPES OF 1500 TO 2000 J/KG. EARLY MORNING IS NOT AS CONDUCIVE TO SEVERE WEATHER BUT CAN NOT RULE IT OUT. GFS AND EC STILL INDICATING COLD FRONTS LATE NEXT WEEK...ONE MOVING THROUGH THURSDAY...WITH SECOND REINFORCEMENT OF COLDER AIR SATURDAY. WILL CONTINUE TO TREND TOWARD COLDER TEMPERATURES. RAINFALL POTENTIAL FOR THURSDAY LOOKS LOW...BUT COULD POTENTIALLY SEE SOME OVERRUNNING NEXT WEEKEND. 04 && .PRELIMINARY POINT TEMPS/POPS... ABILENE 89 68 90 68 82 / 0 0 10 20 30 SAN ANGELO 91 67 90 67 85 / 0 0 10 20 20 JUNCTION 89 67 89 69 87 / 0 0 10 20 20 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 04
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
858 AM PDT SAT OCT 20 2012 ...RAINY AND BREEZY WEATHER SUNDAY NIGHT INTO MONDAY... .DISCUSSION...AS OF 8:45 AM PDT SATURDAY...PLENTY OF CLOUDS STILL AROUND THE CWA THIS MORNING -- IN FACT CURRENT SATELLITE IMAGE LOOKS A LOT THIS WHAT WE WOULD SEE DURING THE SUMMER MONTHS. HOWEVER SOME SPOTS ARE STARTING TO BREAK (INCLUDING HERE IN MONTEREY WHERE THE SUN IS NOW OUT) SO MOST LOCATIONS SHOULD END UP SEEING SOME SUNSHINE TODAY. NORTHERLY SURFACE GRADIENT OF 4 MB (WITH WESTERLY PIECE OF 1.7 MB) ALSO SUGGESTS SUNSHINE BY AFTERNOON. CURRENT HIGH TEMPERATURE FORECAST HAS ONLY A MINOR RANGE WITH 60S TO LOW 70S AT THE COAST AND MOSTLY 70S INLAND. MAIN STORY CONTINUES TO BE THE MAJOR CHANGE IN THE WEATHER AS A STRONG STORM SYSTEM FOR THIS TIME OF THE YEAR CRASHES INTO THE WEST COAST STARTING SUNDAY EVENING WITH THE MAIN IMPACT FOR US SUNDAY NIGHT INTO MONDAY. LATEST SUITE OF MODELS ARE NOW IN AND ALTHOUGH RAIN LOOKS LIKELY FOR ALL SPOTS THE VAST MAJORITY OF THE ENERGY APPEARS TO STAY LOCATED NORTH OF SF BAY. JUST GOT OFF A CALL WITH CNRFC AND CONFIDENCE IS FAIRLY HIGH WITH THE PLACEMENT OF THE HIGHER QPF VALUES FOR THE NORTH BAY AND POINTS TO THE NORTH. WITHOUT SOUNDING LIKE A BROKEN RECORD....TODAY IS A VERY GOOD DAY TO MAKE SURE THAT ALL GUTTERS AND STORM DRAINS ARE CLEARED OUT. 12Z MODELS BRING THE HEAVIEST RAINFALL ACROSS SUNDAY NIGHT INTO MONDAY MORNING AS THE COLD FRONT PUSHES ACROSS OUR CWA. GUSTY WINDS CAN ALSO BE EXPECTED AT THIS TIME WITH 850 MB SPEEDS NEAR 40 KT (ALTHOUGH IT IS IMPORTANT TO NOTE THAT THIS IS A DECREASE OF NEARLY 10 KT COMPARED TO PREVIOUS RUNS). SCATTERED SHOWERS ARE EXPECTED TO CONTINUE AT LEAST INTO TUESDAY ALTHOUGH AMOUNTS ARE ANTICIPATED TO BE LESS. WOULD NOT BE SURPRISED IF SOME PARTS OF THE NORTH BAY PICK UP AROUND AN INCH AND A HALF BY TUESDAY MORNING FROM THE ENTIRE EVENT. .PREVIOUS DISCUSSION...CLOUDS COVER MOST OF THE DISTRICT EARLY THIS MORNING EXCEPT FOR SOME OF THE HIGHER PEAKS. TEMPERATURES ARE GENERALLY RUNNING IN THE 50S WHICH IS ABOUT 4-8 DEGREES COOLER THAN YESTERDAY AT THIS TIME. EXPECT SLOW CLEARING THIS MORNING AS ONSHORE WINDS WILL BE INCREASING THROUGH THE DAY. COMPARED TO FRIDAY...HIGHS THIS AFTERNOON WILL ONCE AGAIN COOL A FEW DEGREES WITH A STRONG SEA-BREEZE EXPECTED THIS AFTERNOON AS DEPICTED BY THE NAM MODEL WITH AN INITIAL DRY BOUNDARY AND WIND SHIFT FORECAST TO REACH THE COAST LATE THIS AFTERNOON. IN PARTICULAR THIS WILL ALLOW WINDS TO PICK UP OVER THE OCEAN WITH GALE WARNINGS BEING HOISTED. HEADS UP FOR FOLKS HEADING OUT ON THE WATER THIS WEEKEND. INCOMING STORM IS NOW NOTED ON SATELLITE IMAGERY OUT NEAR 160 WEST AND ASSOCIATED WITH STRONG JET STREAM ENERGY THAT WILL INTERACT WITH UNSEASONABLY COLD AIR SPILLING OUT OF THE GULF OF ALASKA. HIGH CLOUDS WILL BE NOTED EARLY SUNDAY MORNING AND INCREASE THROUGH THE DAY. IF ANYTHING MODELS ARE TRENDING FASTER WITH THE ARRIVAL OF THE INCOMING SYSTEM. CANT COMPLETELY RULE OUT A STRAY SHOWER OR SPRINKLE OR TWO ACROSS THE BAY AREA AS EARLY AS SUNDAY AFTERNOON. HOWEVER ANY RENEGADE SHOWERS WILL BE BRIEF AND SPOTTY LATE IN THE DAY. THERE REMAINS BETTER MODEL CONSENSUS FOR LIGHT RAIN OVERSPREADING THE BAY AREA AFTER 03Z MONDAY AND THEN INCREASING IN INTENSITY IN THE PRE-DAWN HOURS OF MONDAY. THE MONDAY MORNING COMMUTE WILL LIKELY BE UGLY WITH WET ROADS FOR THE ENTIRE BAY AREA AND LIKELY DOWN TO THE MONTEREY BAY REGION. THE ACTUAL FRONTAL PASSAGE LOOKS TO OCCUR SOMETIME BETWEEN 12-18Z MONDAY. DURING THIS TIME FRAME A BRIEF WINDOW OF MODERATE RAINFALL WILL LIKELY OCCUR WITH THE HEAVIEST RAINFALL IN THE NORTH BAY. IN ADDITION PRE-FRONTAL WINDS FROM THE SOUTHEAST WILL SHIFT TO SW. LOCALIZED BUT FREQUENT GUSTS IN THE 30-40 MPH RANGE WILL BE LIKELY. HISTORICALLY EARLY SEASON FRONTAL PASSAGES SUCH AS THIS BRING DOWN WEAK OR DISEASED TREES AND LIMBS WHICH CAN LEAD TO POWER OUTAGES AND OTHER HAZARDS. ANY STEADY RAIN SHOULD TAPER TO SHOWERS BY MONDAY AFTERNOON AND EVENING. UNSEASONABLY COLD AIR ALOFT WILL FILTER IN BEHIND THE FRONT AND SHOWER CHANCES WILL CONTINUE INTO TUESDAY. THE COLD AIR WITH THIS SYSTEM WILL ALSO BRING SNOW TO THE SIERRA AND IMPACT ROADS UP THERE. BY ALL ACCOUNTS THE INCOMING SYSTEM LOOKS FAIRLY FORMIDABLE AND THE RAPID TRANSITION FROM DRY AND STABLE WEATHER TO WET WEATHER WILL BE FAIRLY DRAMATIC. TODAY AND SUNDAY WILL OFFER THE BEST CHANCE FOR ANY PRE-STORM PREPARATIONS SUCH AS CLEANING OF GUTTERS AND CULVERTS OR TRIMMING OF WEAKENED TREE BRANCHES. THE PATTERN FROM WEDS THROUGH FRIDAY REMAINS ACTIVE FOR LATE OCTOBER BUT LATEST TRENDS SHOW THE STORM TRACK SHIFTING NORTH OF INTERSTATE 80. HOWEVER SOME SHOWER OR LIGHT RAIN CHANCES WILL LINGER ESPECIALLY FOR THE NORTH BAY THROUGH THE WEEK. LOOKS LIKE THE RIDGE REBUILDS BY ABOUT NEXT FRIDAY WITH A DRYING AND WARMING TREND BY NEXT WEEKEND. WILL FRESHEN UP THE SPECIAL WEATHER STATEMENT FOR THE SUNDAY NIGHT/MONDAY SYSTEM. && .AVIATION...AS OF 4:25 AM SATURDAY...VERY DIFFICULT FORECAST THIS MORNING...AS MARINE LAYER CONTINUES TO DEEPEN AHEAD OF A STORM SYSTEM. MODERATE ONSHORE FLOW OVERNIGHT ALLOWED STRATUS TO MOVE WELL INLAND...IMPACTING ALL TERMINALS. MOST OF THE SHORT TERM MODELS...SUCH AS THE NAM...WRF...AND HRRR ARE PESSIMISTIC...WITH VFR CONDITIONS AFTER 20Z. OTHERWISE...MODERATE TO STRONG ONSHORE WINDS WILL DEVELOP THIS AFTERNOON...WITH A POSSIBLE RETURN OF STRATUS OVERNIGHT. VICINITY OF KSFO....IFR CIGS ARE FORECAST TO LIFT TO MVFR BY 18Z...WITH VFR AFTER 20Z. LOW CONFIDENCE. MODERATE TO STRONG ONSHORE WINDS THIS AFTERNOON...WITH POSSIBLE GUSTS NEAR 30 KT AT KSFO BETWEEN 22Z TODAY AND 05Z SUNDAY. KSFO BRIDGE APPROACH...APPROACH MAY BE IMPACTED THROUGH 21Z. MONTEREY BAY AREA TERMINALS...IFR TO LIFR CIGS POSSIBLE THROUGH AT LEAST 20Z. POSSIBLE ALL DAY EVENT AT KMRY. LOW CONFIDENCE. && .MARINE...AS OF 4:30 AM PDT SATURDAY...SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE EASTERN PACIFIC TODAY INTO SUNDAY. THIS WILL RESULT IN MODERATE TO STRONG NORTHERLY WINDS OVER THE REGION. WINDS WILL SIGNIFICANTLY INCREASE LATE THIS MORNING OVER THE NORTHERN WATERS...WITH GUSTS TO 40 KT POSSIBLE THROUGH EARLY SUNDAY MORNING. THESE STRONG WINDS WILL RESULT IN STEEP FRESH SWELLS. WINDS WILL BEGIN TO SLOWLY SUBSIDE SUNDAY MORNING INTO SUNDAY AFTERNOON. BY LATE SUNDAY NIGHT INTO EARLY MONDAY MORNING...A STORM SYSTEM WILL APPROACH THE REGION...RAPIDLY SWITCHING WINDS FROM THE NORTH TO THE SOUTH. SOUTHERLY WINDS WITH GUSTS TO 30 KT WILL BE POSSIBLE FOR A SHORT PERIOD OF TIME EARLY MONDAY. MARINERS ARE ENCOURAGED TO CONTINUE TO MONITOR THE FORECAST CLOSELY THROUGH THE WEEKEND INTO EARLY NEXT WEEK. && .MTR WATCHES/WARNINGS/ADVISORIES... .TDAY...SCA...PIGEON PT TO PT PINOS 0-10 NM FROM 1 PM SCA...PT ARENA TO PT REYES 0-10 NM UNTIL 11 AM SCA...PT ARENA TO PIGEON PT 10-60 NM UNTIL 11 AM GLW...PT ARENA TO PT REYES 0-10 NM FROM 11 AM GLW...PT ARENA TO PIGEON PT 10-60 NM FROM 11 AM SCA...PT REYES TO PIGEON PT 0-10 NM SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM SCA...SF BAY FROM 1 PM SCA...MRY BAY FROM 1 PM && $$ PUBLIC FORECAST: BELL/RWW AVIATION/MARINE: RILEY VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO FOLLOW US ON FACEBOOK AND TWITTER AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.SANFRANCISCOBAYAREA.GOV WWW.TWITTER.COM/NWSBAYAREA
AREA FORECAST DISCUSSION
NWS SAN FRANCISCO BAY AREA
434 AM PDT SAT OCT 20 2012 ...RAIN AND BREEZY WEATHER SUNDAY NIGHT INTO MONDAY... .DISCUSSION...AS OF 4:17 AM PDT SATURDAY...CLOUDS COVER MOST OF THE DISTRICT EARLY THIS MORNING EXCEPT FOR SOME OF THE HIGHER PEAKS. TEMPERATURES ARE GENERALLY RUNNING IN THE 50S WHICH IS ABOUT 4-8 DEGREES COOLER THAN YESTERDAY AT THIS TIME. EXPECT SLOW CLEARING THIS MORNING AS ONSHORE WINDS WILL BE INCREASING THROUGH THE DAY. COMPARED TO FRIDAY...HIGHS THIS AFTERNOON WILL ONCE AGAIN COOL A FEW DEGREES WITH A STRONG SEA-BREEZE EXPECTED THIS AFTERNOON AS DEPICTED BY THE NAM MODEL WITH AN INITIAL DRY BOUNDARY AND WIND SHIFT FORECAST TO REACH THE COAST LATE THIS AFTERNOON. IN PARTICULAR THIS WILL ALLOW WINDS TO PICK UP OVER THE OCEAN WITH GALE WARNINGS BEING HOISTED. HEADS UP FOR FOLKS HEADING OUT ON THE WATER THIS WEEKEND. INCOMING STORM IS NOW NOTED ON SATELLITE IMAGERY OUT NEAR 160 WEST AND ASSOCIATED WITH STRONG JET STREAM ENERGY THAT WILL INTERACT WITH UNSEASONABLY COLD AIR SPILLING OUT OF THE GULF OF ALASKA. HIGH CLOUDS WILL BE NOTED EARLY SUNDAY MORNING AND INCREASE THROUGH THE DAY. IF ANYTHING MODELS ARE TRENDING FASTER WITH THE ARRIVAL OF THE INCOMING SYSTEM. CANT COMPLETELY RULE OUT A STRAY SHOWER OR SPRINKLE OR TWO ACROSS THE BAY AREA AS EARLY AS SUNDAY AFTERNOON. HOWEVER ANY RENEGADE SHOWERS WILL BE BRIEF AND SPOTTY LATE IN THE DAY. THERE REMAINS BETTER MODEL CONSENSUS FOR LIGHT RAIN OVERSPREADING THE BAY AREA AFTER 03Z MONDAY AND THEN INCREASING IN INTENSITY IN THE PRE-DAWN HOURS OF MONDAY. THE MONDAY MORNING COMMUTE WILL LIKELY BE UGLY WITH WET ROADS FOR THE ENTIRE BAY AREA AND LIKELY DOWN TO THE MONTEREY BAY REGION. THE ACTUAL FRONTAL PASSAGE LOOKS TO OCCUR SOMETIME BETWEEN 12-18Z MONDAY. DURING THIS TIME FRAME A BRIEF WINDOW OF MODERATE RAINFALL WILL LIKELY OCCUR WITH THE HEAVIEST RAINFALL IN THE NORTH BAY. IN ADDITION PRE-FRONTAL WINDS FROM THE SOUTHEAST WILL SHIFT TO SW. LOCALIZED BUT FREQUENT GUSTS IN THE 30-40 MPH RANGE WILL BE LIKELY. HISTORICALLY EARLY SEASON FRONTAL PASSAGES SUCH AS THIS BRING DOWN WEAK OR DISEASED TREES AND LIMBS WHICH CAN LEAD TO POWER OUTAGES AND OTHER HAZARDS. ANY STEADY RAIN SHOULD TAPER TO SHOWERS BY MONDAY AFTERNOON AND EVENING. UNSEASONABLY COLD AIR ALOFT WILL FILTER IN BEHIND THE FRONT AND SHOWER CHANCES WILL CONTINUE INTO TUESDAY. THE COLD AIR WITH THIS SYSTEM WILL ALSO BRING SNOW TO THE SIERRA AND IMPACT ROADS UP THERE. BY ALL ACCOUNTS THE INCOMING SYSTEM LOOKS FAIRLY FORMIDABLE AND THE RAPID TRANSITION FROM DRY AND STABLE WEATHER TO WET WEATHER WILL BE FAIRLY DRAMATIC. TODAY AND SUNDAY WILL OFFER THE BEST CHANCE FOR ANY PRE-STORM PREPARATIONS SUCH AS CLEANING OF GUTTERS AND CULVERTS OR TRIMMING OF WEAKENED TREE BRANCHES. THE PATTERN FROM WEDS THROUGH FRIDAY REMAINS ACTIVE FOR LATE OCTOBER BUT LATEST TRENDS SHOW THE STORM TRACK SHIFTING NORTH OF INTERSTATE 80. HOWEVER SOME SHOWER OR LIGHT RAIN CHANCES WILL LINGER ESPECIALLY FOR THE NORTH BAY THROUGH THE WEEK. LOOKS LIKE THE RIDGE REBUILDS BY ABOUT NEXT FRIDAY WITH A DRYING AND WARMING TREND BY NEXT WEEKEND. WILL FRESHEN UP THE SPECIAL WEATHER STATEMENT FOR THE SUNDAY NIGHT/MONDAY SYSTEM. && .AVIATION...AS OF 4:25 AM SATURDAY...VERY DIFFICULT FORECAST THIS MORNING...AS MARINE LAYER CONTINUES TO DEEPEN AHEAD OF A STORM SYSTEM. MODERATE ONSHORE FLOW OVERNIGHT ALLOWED STRATUS TO MOVE WELL INLAND...IMPACTING ALL TERMINALS. MOST OF THE SHORT TERM MODELS...SUCH AS THE NAM...WRF...AND HRRR ARE PESSIMISTIC...WITH VFR CONDITIONS AFTER 20Z. OTHERWISE...MODERATE TO STRONG ONSHORE WINDS WILL DEVELOP THIS AFTERNOON...WITH A POSSIBLE RETURN OF STRATUS OVERNIGHT. VICINITY OF KSFO....IFR CIGS ARE FORECAST TO LIFT TO MVFR BY 18Z...WITH VFR AFTER 20Z. LOW CONFIDENCE. MODERATE TO STRONG ONSHORE WINDS THIS AFTERNOON...WITH POSSIBLE GUSTS NEAR 30 KT AT KSFO BETWEEN 22Z TODAY AND 05Z SUNDAY. KSFO BRIDGE APPROACH...APPROACH MAY BE IMPACTED THROUGH 21Z. MONTEREY BAY AREA TERMINALS...IFR TO LIFR CIGS POSSIBLE THROUGH AT LEAST 20Z. POSSIBLE ALL DAY EVENT AT KMRY. LOW CONFIDENCE. && .MARINE...AS OF 4:30 AM PDT SATURDAY...SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE EASTERN PACIFIC TODAY INTO SUNDAY. THIS WILL RESULT IN MODERATE TO STRONG NORTHERLY WINDS OVER THE REGION. WINDS WILL SIGNIFICANTLY INCREASE LATE THIS MORNING OVER THE NORTHERN WATERS...WITH GUSTS TO 40 KT POSSIBLE THROUGH EARLY SUNDAY MORNING. THESE STRONG WINDS WILL RESULT IN STEEP FRESH SWELLS. WINDS WILL BEGIN TO SLOWLY SUBSIDE SUNDAY MORNING INTO SUNDAY AFTERNOON. BY LATE SUNDAY NIGHT INTO EARLY MONDAY MORNING...A STORM SYSTEM WILL APPROACH THE REGION...RAPIDLY SWITCHING WINDS FROM THE NORTH TO THE SOUTH. SOUTHERLY WINDS WITH GUSTS TO 30 KT WILL BE POSSIBLE FOR A SHORT PERIOD OF TIME EARLY MONDAY. MARINERS ARE ENCOURAGED TO CONTINUE TO MONITOR THE FORECAST CLOSELY THROUGH THE WEEKEND INTO EARLY NEXT WEEK. && .MTR WATCHES/WARNINGS/ADVISORIES... .TDAY...SCA...PIGEON PT TO PT PINOS 0-10 NM FROM 1 PM SCA...PT ARENA TO PT REYES 0-10 NM UNTIL 11 AM SCA...PT ARENA TO PIGEON PT 10-60 NM UNTIL 11 AM GLW...PT ARENA TO PT REYES 0-10 NM FROM 11 AM GLW...PT ARENA TO PIGEON PT 10-60 NM FROM 11 AM SCA...PT REYES TO PIGEON PT 0-10 NM FROM 8 AM SCA...PT PINOS TO PT PIEDRAS BLANCAS 0-10 NM FROM 8 AM SCA...PIGEON PT TO PT PIEDRAS BLANCAS 10-60 NM FROM 8 AM SCA...SF BAY FROM 1 PM SCA...MRY BAY FROM 1 PM && $$ PUBLIC FORECAST: RWW AVIATION/MARINE: RILEY VISIT US AT WWW.WEATHER.GOV/SANFRANCISCO FOLLOW US ON FACEBOOK AND TWITTER AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.SANFRANCISCOBAYAREA.GOV WWW.TWITTER.COM/NWSBAYAREA
AREA FORECAST DISCUSSION
NWS JACKSON KY
950 AM EDT SAT OCT 20 2012 .UPDATE... ISSUED AT 950 AM EDT SAT OCT 20 2012 THE FORECAST APPEARS TO BE ON TRACK THIS MORNING WITH MINIMAL TWEAKS TO HOURLY TEMPS AND DEW PTS. LOOKING AT THE FIRST ECHOS OF THE DAY DRIFTING THROUGH FLEMING AND ROWAN COUNTIES IT IS APPARENT THAT LITTLE IF ANY OF THIS IS REACHING THE GROUND AND WILL CONTINUE WITH THE IDEA OF SCATTERED SPRINKLES THROUGH THE DAY PRIMARILY ALONG AND NORTH OF THE MOUNTAIN PARKWAY. ZONES AND HWO LOOK GOOD...AND NO UPDATE APPEARS TO BE NEEDED THERE ATTM. UPDATE ISSUED AT 724 AM EDT SAT OCT 20 2012 TEMPERATURES HAVE STAYED UP IN THE MID AND UPPER 40S THIS MORNING DUE TO THE EXTENSIVE CLOUD COVER. HAVE FRESHENED UP THE FORECAST GRIDS TO RESEMBLE THIS. OTHERWISE...THE FORECAST IS GOOD TO GO. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 346 AM EDT SAT OCT 20 2012 CURRENT CONDITIONS ACROSS EASTERN KENTUCKY FEATURE AN UPPER LEVEL LOW CENTERED OVER MI KEEPING CONTINUED CLOUD COVER OVER THE OHIO VALLEY. THEREFORE...THIS WILL KEEP MORNING TEMPERATURES WARM IN THE MID 40S. WITH THE HEATING OF DAY AND AT LEAST A TAD OF INSTABILITY AND THE UPPER LEVEL LOW PROVIDING SEVERAL WEAK VORT MAXES MOVING THROUGH...WILL KEEP ISOLATED SPRINKLES ACROSS THE AREA THROUGH THE AFTERNOON...MAINLY ALONG AND NORTH OF THE MOUNTAIN PARKWAY. GIVEN THE CURRENT TREND OF THE MODELS...WILL LEAN TOWARD A SLOWER EXIT OF THE UPPER LOW TO THE NORTHEAST. THEREFORE...KEEPING HIGH TEMPS FOR TODAY TEMPERED TO THE UPPER 50S. LOCALES SUCH AS BLACK MOUNTAIN WILL STRUGGLE TO REACH THE MID 40S. HEADING INTO TONIGHT...THE FORECAST CHALLENGE ARISES...AS THE NAM AND RUC HINT AT THE UPPER LOW AND ASSOCIATED 850 MOISTURE/CLOUD COVER FINALLY EXITING TO THE NORTHEAST. THIS PROCESS CONTINUING THROUGH TONIGHT WILL SLOWLY ALLOW CLEARING FROM THE SOUTHWEST TO THE NORTHEAST. SO HAVE TRIED TO SHOW THIS IN THE SUN NIGHT MIN TEMPS AS STATIONS SUCH AS MONTICELLO COULD BOTTOM OUT INTO THE MID 30S TONIGHT. SO WENT WITH A SIGNIFICANT RIDGE VALLEY SPLIT WHERE AREAS WILL CLEAR OUT ALONG WITH A GENERAL GRADIENT WITH THE SOUTHWEST BEING COOLER TO THE NORTHEAST BEING WARMER AS THE CLOUD COVER EXITS. THIS WILL ALSO ALLOW FOR SOME EXTENSIVE FOG DEVELOPMENT TONIGHT ESPECIALLY WHERE AREAS CLEAR OUT. THE COLDEST LOCATIONS WILL ALSO SEE SOME PATCHY FROST. FOR SUNDAY...CLOUD COVER IS EXPECT TO CLEAR OUT WITH A SHORTWAVE RIDGE OVERHEAD AND AN OVERALL GREAT WEATHER DAY WITH LIGHT SOUTHERLY WINDS. HEATING TO START THE DAY WILL BE HINDERED AT FIRST AS MORNING FOG WILL BE SLOW TO BURN OFF. HEADING INTO THE COLDER MONTHS MORNING FOG WILL TAKE A BIT LATER TO CLEAR OUT. BUT SUNDAYS HIGHS WILL QUICKLY WARM INTO THE UPPER 60S AND AROUND 70 IN SOUTHERLY FLOW. SO A PLEASANT AND DRY FORECAST IS ON TAP BY SUNDAY. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 346 AM EDT SAT OCT 20 2012 AT THE START OF THE PERIOD...A TROUGH IS EXPECTED TO BE DEPARTING THE NORTHEASTERN US WITH RIDGING EXTENDING FROM MEXICO NORTH INTO THE WESTERN GULF AND MUCH OF THE SOUTHEASTERN US AND MS VALLEY TO LOWER OH VALLEY REGIONS. MEANWHILE A TROUGH IS EXPECTED TO BE DIGGING OFF THE NORTHWEST COAST. A COUPLE OF SHORTWAVES PER MODEL CONSENSUS ARE EXPECTED TO BE WORKING AROUND THE SOUTHEASTERN RIDGING...ONE MOVING THROUGH THE PLAINS AND APPROACHING THE MID MS VALLEY REGION AT THE START OF THE PERIOD WITH ANOTHER WORKING FROM THE DESERT SOUTHWEST TOWARD THE SOUTHERN PLAINS. THROUGH MONDAY NIGHT AND TUESDAY...HEIGHTS WILL RISE ALONG THE EASTERN SEABOARD AS THE TROUGH DEPARTS THE NORTHEASTERN US WITH RIDGING EXTENDING FROM MEXICO ACROSS THE GULF AND INTO THE SOUTHEASTERN STATES AROUND 12Z TUE PER MODEL CONSENSUS. THE FIRST OF THE SHORTWAVES MENTIONED PREVIOUSLY IS PROGGED TO PASS WELL TO OUR NW AND THEN NORTH AS IT MOVES IT AROUND THE RIDGING FROM SUN NIGHT INTO MONDAY. FAIRLY CLOSE ON ITS HEELS WILL BE THE NEXT SHORTWAVE WORKING ACROSS THE PLAINS AND TOWARD THE MID MS VALLEY REGION AND THEN NORTH OF THE AREA ON TUE. BOTH OF THESE SHOULD BRING JUST SOME HIGH AND MID CLOUDS FOR THE MOST PART...WITH ANY PRECIP CHANCES WELL WEST AND NORTH OF THE REGION. RIDING SHOULD THEN REASSERT ITSELF AT MIDWEEK OVER THE WESTERN GULF AND INTO THE SOUTHEASTERN US...WITH A RATHER BROAD TROUGH OVER THE WESTERN US AND EAST INTO THE PLAINS. A SHORTWAVE TROUGH ASSOCIATED WITH THIS BROAD THROUGH SHOULD GRADUALLY EJECT NORTHEAST TOWARD THE GREAT LAKES ON THU INTO THU NIGHT WITH RATHER ZONAL FLOW LEFT IN PLACE AT MIDWEEK. THERE ARE TIMING DIFFERENCES WITH THIS LAST SHORTWAVE AND THE EVOLUTION/STRENGTH OF A CLOSED LOW OVER THE GREAT LAKES/ONTARIO AREA AT THE END OF THE WEEK. HOWEVER...YET ANOTHER IN A SERIES OF SFC LOWS TRACKING ACROSS THE PLAINS AND INTO THE GREAT LAKES REGION IS ANTICIPATED WITH THE TRAILING RATHER SHEARED OUT BOUNDARY WORKING INTO THE REGION LATE IN THE PERIOD. THE ECMWF RUNS HAVE BEEN FASTER WITH THIS BOUNDARY OVER THE PAST FEW RUNS COMPARED TO THE GFS RUN. SFC RIDGING SHIFTING EAST INITIALLY IN THE PERIOD ALONG WITH SOME SUBSIDENCE ASSOCIATED WITH HEIGHT RISES SHOULD BE FAVORABLE FOR RIVER VALLEY FOG ON SUN NIGHT AND A RIDGE/VALLEY TEMP SPLIT. MANY OF THE VALLEY LOCATIONS...ESPECIALLY EAST SHOULD REACH THE UPPER 30S TO LOW 40S ON SUN NIGHT. TEMPERATURES WILL CONTINUE TO MODERATE ASSOCIATED WITH THE RISING HEIGHTS AND SOUTHERLY FLOW ON MON. THE MODEL CONSENSUS IS CURRENTLY BELOW THE MEX NUMBERS...BUT NUDGED TEMPS A DEGREE ABOVE THE MODEL CONSENSUS FOR MON. MIN T SHOULD MODERATE ON MON NIGHT AS WELL...THOUGH A RIDGE/VALLEY SPLIT IS STILL EXPECTED OVER THE SOUTHEASTERN COUNTIES WITH A SIMILAR MAGNITUDE AS SUN NIGHT. MIN T ON TUE NIGHT SHOULD BE A COLDER ON AVERAGE COMPARED TO MON NIGHT WITH THE RIDGE STARTING TO REASSERT ITSELF AND A BIT LESS CLOUD COVER ON AVERAGE WITH YET ANOTHER IN A SERIES OF RIDGE/VALLEY TEMP SPLITS. WED NIGHT SHOULD ALSO FAVOR A RIDGE/VALLEY TEMP SPLIT...BUT THU NIGHT SHOULD FEATURE A MINIMAL OR NO RIDGE/VALLEY TEMP SPLIT AS THE GRADIENT INCREASES AHEAD OF AN APPROACHING COLD FRONT. SOME TERRAIN ADJUSTMENTS WERE MADE TO THE GRID LOAD FOR MIN T FROM MON NIGHT THROUGH WED NIGHT TO REFLECT THE ABOVE MENTIONED RIDGE/VALLEY TEMP SPLITS. MAX TEMPS WILL MODERATE FURTHER INTO MIDWEEK AND REMAIN ABOVE NORMAL THROUGH THE END OF THE PERIOD. MAX TEMPS SHOULD NEAR 15 DEGREES ABOVE NORMAL ON WED AS 850 MB TEMPS REACH ABOUT THE 12 TO 15C RANGE. WED IS EXPECTED TO BE THE WARMEST DAY. DURING THE PAST COUPLE OF WARMER DAYS THE MEX HAS BEEN TOO WARM WITH MAX T AND THE GRID LOAD TEMPS IN THE UPPER 70S WERE ACCEPTED. THE ONLY POPS IN THE PERIOD WILL COME AT THE END OF THE PERIOD. IF THE FASTER ECMWF IS RIGHT OR MODELS TREND TOWARD IT...THEN POPS MAY NEED TO BE INCREASED ON THU NIGHT. HOWEVER...THE MODEL CONSENSUS GRID LOAD FAVORED POPS MAINLY ON FRI...AND THIS SEEMED TO BE A REASONABLE COMPROMISE GIVEN THE MODEL DIFFERENCES NOTED ABOVE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 724 AM EDT SAT OCT 20 2012 WILL EXPECT A 4 KFT LAYER TO BE PERSISTENT THROUGH THE DAY TODAY WITH A 5 TO 10 KNOT WEST WINDS BEFORE DECOUPLING BY 23Z. WITH CLEARING SKIES TONIGHT...PATCHY DENSE FOG WILL DEVELOP. SME AND LOZ WILL DROP TO VLIFR VISIBILITY BY 10Z TONIGHT. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SHALLENBERGER/MB SHORT TERM...SHALLENBERGER LONG TERM....JP AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS JACKSON KY
722 AM EDT SAT OCT 20 2012 .UPDATE... ISSUED AT 724 AM EDT SAT OCT 20 2012 TEMPERATURES HAVE STAYED UP IN THE MID AND UPPER 40S THIS MORNING DUE TO THE EXTENSIVE CLOUD COVER. HAVE FRESHENED UP THE FORECAST GRIDS TO RESEMBLE THIS. OTHERWISE...THE FORECAST IS GOOD TO GO. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 346 AM EDT SAT OCT 20 2012 CURRENT CONDITIONS ACROSS EASTERN KENTUCKY FEATURE AN UPPER LEVEL LOW CENTERED OVER MI KEEPING CONTINUED CLOUD COVER OVER THE OHIO VALLEY. THEREFORE...THIS WILL KEEP MORNING TEMPERATURES WARM IN THE MID 40S. WITH THE HEATING OF DAY AND AT LEAST A TAD OF INSTABILITY AND THE UPPER LEVEL LOW PROVIDING SEVERAL WEAK VORT MAXES MOVING THROUGH...WILL KEEP ISOLATED SPRINKLES ACROSS THE AREA THROUGH THE AFTERNOON...MAINLY ALONG AND NORTH OF THE MOUNTAIN PARKWAY. GIVEN THE CURRENT TREND OF THE MODELS...WILL LEAN TOWARD A SLOWER EXIT OF THE UPPER LOW TO THE NORTHEAST. THEREFORE...KEEPING HIGH TEMPS FOR TODAY TEMPERED TO THE UPPER 50S. LOCALES SUCH AS BLACK MOUNTAIN WILL STRUGGLE TO REACH THE MID 40S. HEADING INTO TONIGHT...THE FORECAST CHALLENGE ARISES...AS THE NAM AND RUC HINT AT THE UPPER LOW AND ASSOCIATED 850 MOISTURE/CLOUD COVER FINALLY EXITING TO THE NORTHEAST. THIS PROCESS CONTINUING THROUGH TONIGHT WILL SLOWLY ALLOW CLEARING FROM THE SOUTHWEST TO THE NORTHEAST. SO HAVE TRIED TO SHOW THIS IN THE SUN NIGHT MIN TEMPS AS STATIONS SUCH AS MONTICELLO COULD BOTTOM OUT INTO THE MID 30S TONIGHT. SO WENT WITH A SIGNIFICANT RIDGE VALLEY SPLIT WHERE AREAS WILL CLEAR OUT ALONG WITH A GENERAL GRADIENT WITH THE SOUTHWEST BEING COOLER TO THE NORTHEAST BEING WARMER AS THE CLOUD COVER EXITS. THIS WILL ALSO ALLOW FOR SOME EXTENSIVE FOG DEVELOPMENT TONIGHT ESPECIALLY WHERE AREAS CLEAR OUT. THE COLDEST LOCATIONS WILL ALSO SEE SOME PATCHY FROST. FOR SUNDAY...CLOUD COVER IS EXPECT TO CLEAR OUT WITH A SHORTWAVE RIDGE OVERHEAD AND AN OVERALL GREAT WEATHER DAY WITH LIGHT SOUTHERLY WINDS. HEATING TO START THE DAY WILL BE HINDERED AT FIRST AS MORNING FOG WILL BE SLOW TO BURN OFF. HEADING INTO THE COLDER MONTHS MORNING FOG WILL TAKE A BIT LATER TO CLEAR OUT. BUT SUNDAYS HIGHS WILL QUICKLY WARM INTO THE UPPER 60S AND AROUND 70 IN SOUTHERLY FLOW. SO A PLEASANT AND DRY FORECAST IS ON TAP BY SUNDAY. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 346 AM EDT SAT OCT 20 2012 AT THE START OF THE PERIOD...A TROUGH IS EXPECTED TO BE DEPARTING THE NORTHEASTERN US WITH RIDGING EXTENDING FROM MEXICO NORTH INTO THE WESTERN GULF AND MUCH OF THE SOUTHEASTERN US AND MS VALLEY TO LOWER OH VALLEY REGIONS. MEANWHILE A TROUGH IS EXPECTED TO BE DIGGING OFF THE NORTHWEST COAST. A COUPLE OF SHORTWAVES PER MODEL CONSENSUS ARE EXPECTED TO BE WORKING AROUND THE SOUTHEASTERN RIDGING...ONE MOVING THROUGH THE PLAINS AND APPROACHING THE MID MS VALLEY REGION AT THE START OF THE PERIOD WITH ANOTHER WORKING FROM THE DESERT SOUTHWEST TOWARD THE SOUTHERN PLAINS. THROUGH MONDAY NIGHT AND TUESDAY...HEIGHTS WILL RISE ALONG THE EASTERN SEABOARD AS THE TROUGH DEPARTS THE NORTHEASTERN US WITH RIDGING EXTENDING FROM MEXICO ACROSS THE GULF AND INTO THE SOUTHEASTERN STATES AROUND 12Z TUE PER MODEL CONSENSUS. THE FIRST OF THE SHORTWAVES MENTIONED PREVIOUSLY IS PROGGED TO PASS WELL TO OUR NW AND THEN NORTH AS IT MOVES IT AROUND THE RIDGING FROM SUN NIGHT INTO MONDAY. FAIRLY CLOSE ON ITS HEELS WILL BE THE NEXT SHORTWAVE WORKING ACROSS THE PLAINS AND TOWARD THE MID MS VALLEY REGION AND THEN NORTH OF THE AREA ON TUE. BOTH OF THESE SHOULD BRING JUST SOME HIGH AND MID CLOUDS FOR THE MOST PART...WITH ANY PRECIP CHANCES WELL WEST AND NORTH OF THE REGION. RIDING SHOULD THEN REASSERT ITSELF AT MIDWEEK OVER THE WESTERN GULF AND INTO THE SOUTHEASTERN US...WITH A RATHER BROAD TROUGH OVER THE WESTERN US AND EAST INTO THE PLAINS. A SHORTWAVE TROUGH ASSOCIATED WITH THIS BROAD THROUGH SHOULD GRADUALLY EJECT NORTHEAST TOWARD THE GREAT LAKES ON THU INTO THU NIGHT WITH RATHER ZONAL FLOW LEFT IN PLACE AT MIDWEEK. THERE ARE TIMING DIFFERENCES WITH THIS LAST SHORTWAVE AND THE EVOLUTION/STRENGTH OF A CLOSED LOW OVER THE GREAT LAKES/ONTARIO AREA AT THE END OF THE WEEK. HOWEVER...YET ANOTHER IN A SERIES OF SFC LOWS TRACKING ACROSS THE PLAINS AND INTO THE GREAT LAKES REGION IS ANTICIPATED WITH THE TRAILING RATHER SHEARED OUT BOUNDARY WORKING INTO THE REGION LATE IN THE PERIOD. THE ECMWF RUNS HAVE BEEN FASTER WITH THIS BOUNDARY OVER THE PAST FEW RUNS COMPARED TO THE GFS RUN. SFC RIDGING SHIFTING EAST INITIALLY IN THE PERIOD ALONG WITH SOME SUBSIDENCE ASSOCIATED WITH HEIGHT RISES SHOULD BE FAVORABLE FOR RIVER VALLEY FOG ON SUN NIGHT AND A RIDGE/VALLEY TEMP SPLIT. MANY OF THE VALLEY LOCATIONS...ESPECIALLY EAST SHOULD REACH THE UPPER 30S TO LOW 40S ON SUN NIGHT. TEMPERATURES WILL CONTINUE TO MODERATE ASSOCIATED WITH THE RISING HEIGHTS AND SOUTHERLY FLOW ON MON. THE MODEL CONSENSUS IS CURRENTLY BELOW THE MEX NUMBERS...BUT NUDGED TEMPS A DEGREE ABOVE THE MODEL CONSENSUS FOR MON. MIN T SHOULD MODERATE ON MON NIGHT AS WELL...THOUGH A RIDGE/VALLEY SPLIT IS STILL EXPECTED OVER THE SOUTHEASTERN COUNTIES WITH A SIMILAR MAGNITUDE AS SUN NIGHT. MIN T ON TUE NIGHT SHOULD BE A COLDER ON AVERAGE COMPARED TO MON NIGHT WITH THE RIDGE STARTING TO REASSERT ITSELF AND A BIT LESS CLOUD COVER ON AVERAGE WITH YET ANOTHER IN A SERIES OF RIDGE/VALLEY TEMP SPLITS. WED NIGHT SHOULD ALSO FAVOR A RIDGE/VALLEY TEMP SPLIT...BUT THU NIGHT SHOULD FEATURE A MINIMAL OR NO RIDGE/VALLEY TEMP SPLIT AS THE GRADIENT INCREASES AHEAD OF AN APPROACHING COLD FRONT. SOME TERRAIN ADJUSTMENTS WERE MADE TO THE GRID LOAD FOR MIN T FROM MON NIGHT THROUGH WED NIGHT TO REFLECT THE ABOVE MENTIONED RIDGE/VALLEY TEMP SPLITS. MAX TEMPS WILL MODERATE FURTHER INTO MIDWEEK AND REMAIN ABOVE NORMAL THROUGH THE END OF THE PERIOD. MAX TEMPS SHOULD NEAR 15 DEGREES ABOVE NORMAL ON WED AS 850 MB TEMPS REACH ABOUT THE 12 TO 15C RANGE. WED IS EXPECTED TO BE THE WARMEST DAY. DURING THE PAST COUPLE OF WARMER DAYS THE MEX HAS BEEN TOO WARM WITH MAX T AND THE GRID LOAD TEMPS IN THE UPPER 70S WERE ACCEPTED. THE ONLY POPS IN THE PERIOD WILL COME AT THE END OF THE PERIOD. IF THE FASTER ECMWF IS RIGHT OR MODELS TREND TOWARD IT...THEN POPS MAY NEED TO BE INCREASED ON THU NIGHT. HOWEVER...THE MODEL CONSENSUS GRID LOAD FAVORED POPS MAINLY ON FRI...AND THIS SEEMED TO BE A REASONABLE COMPROMISE GIVEN THE MODEL DIFFERENCES NOTED ABOVE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 724 AM EDT SAT OCT 20 2012 WILL EXPECT A 4 KFT LAYER TO BE PERSISTENT THROUGH THE DAY TODAY WITH A 5 TO 10 KNOT WEST WINDS BEFORE DECOUPLING BY 23Z. WITH CLEARING SKIES TONIGHT...PATCHY DENSE FOG WILL DEVELOP. SME AND LOZ WILL DROP TO VLIFR VISIBILITY BY 10Z TONIGHT. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SHALLENBERGER SHORT TERM...SHALLENBERGER LONG TERM....JP AVIATION...SHALLENBERGER
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1006 AM EDT SAT OCT 20 2012 .SYNOPSIS... A LARGE UPPER LEVEL LOW CENTER WILL SLOWLY MOVE EASTWARD THROUGH THE GREAT LAKES TODAY...AND PROVIDE THE UPPER OHIO VALLEY WITH CLOUDS... SHOWERS AND COOLER TEMPERATURES. HIGH PRESSURE WILL BUILD IN LATER SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... NOT MUCH IN THE WAY OF CHANGES TO THE FORECAST WERE MADE FOR THE MID-MORNING UPDATE. ONLY SLIGHT ADJUSTMENTS TO TEMPERATURES AS CLOUDY SKIES WILL MOST LIKELY KEEP TEMPERATURES FOR RISING TOO MUCH TODAY. OTHERWISE..SCATTERED SHOWERS SHOULD CONTINUE AS THE UPPER LEVEL SHORTWAVE LIFTS THROUGH THE TROUGH. PREVIOUS DISCUSSION FOLLOWS... BLEND OF RECENT SREF AND RAP MODEL OUTPUT...CONFIRMED BY RECENT SURFACE...RADAR...AND SATELLITE DATA...SHOW AN UPPER LEVEL LOW WILL ROTATE EASTWARD THROUGH THE GREAT LAKES TODAY...AND CAUSE CLOUDY SKIES AND SCATTERED SHOWERS ACROSS THE UPPER OHIO VALLEY. SURFACE WINDS CAN GUST UP TO 25 MPH THIS AFTERNOON. ANY REMAINING SHOWERS SHOULD DISSIPATE BY MIDNIGHT. CONTINUED TO FORECAST MOSTLY CLOUDY SKIES...BUT TREND IN RECENT GFS AND NAM MOS SUGGEST CLOUDS COULD BREAK UP OVERNIGHT. HOWEVER IF THIS HAPPENS...ITS POSSIBLE THERE CAN BE PATCHY FOG FORMING LATE TONIGHT. FOR NOW...INCLUDED ISOLATED RIVER VALLEY FOG PATCHES SOUTH AND WEST OF PITTSBURGH NEAR DAWN SUNDAY. FORECASTED HIGH TEMPERATURES TODAY AND LOWS TONIGHT TO BE UP TO 5 DEGREES COOLER THAN NORMAL...PER RECENT GFS AND NAM MOS. && .SHORT TERM /SUNDAY THROUGH MONDAY/... 50H LOW WILL PICK UP SPEED AND MOVE ACROSS NEW ENGLAND ON SUNDAY. ALTHOUGH THE CORE OF THE SYSTEM WILL BE WELL TO THE NORTH...FLOW IN THE MID AN UPPER LEVELS WILL REMAIN CYCLONIC. BECAUSE OF THE AFOREMENTIONED FLOW AND COOLER AIR ALOFT...THINK THAT CLOUDS WILL HOLD AT LEAST INTO SUNDAY AFTERNOON. THE EXTRA CLOUD COVER WILL ALSO KEEP TEMPS BELOW GUIDANCE. MID AND LOW LEVEL WAA BEGINS TO INCREASE SUNDAY NIGHT...AND A SURFACE HIGH WILL MOVE ACROSS THE MID-ATLANTIC. SKIES WILL CLEAR SUNDAY NIGHT. SFC HIGH WILL MOVE VERY LITTLE ON MONDAY...AS UPPER LEVEL RIDGE MOVES OVER OHIO. EXPECT SUNSHINE ON MONDAY WITH NEAR NORMAL TEMPS. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... THE MODELS GENERALLY AGREE THAT AN UPPER LEVEL RIDGE WILL BE IN PLACE OVER MUCH OF THE CENTRAL-EASTERN HALF OF THE US FOR THE START OF THE PERIOD. WHAT REMAINS A BIT MORE INCONSISTENT ARE THE TIMING AND STRENGTH OF THE SYSTEMS THAT DEVELOP AND ATTEMPT TO BREAK DOWN THE RIDGE LATER TUESDAY/WEDNESDAY AND THE TIMING OF THE EVENTUAL COLD FRONT SUGGESTED BY BOTH THE GFS/ECMWF FOR FRIDAY. THE GFS TENDS TO BE A BIT FASTER WITH THE WARM-FRONTAL SHOWERS TUESDAY AFTERNOON/EVENING THAN THE ECMWF...WHICH HAS A STRONGER HIGH PRESSURE RIDGE AND KEEPS MORE OF THE MOISTURE NORTH. AT THIS POINT...WILL MAINTAIN A FORECAST CLOSE TO HPC VALUES FOR POPS. BOTH MODELS AND ENSEMBLE MEANS/MOS GUIDANCE SUGGEST THAT TEMPERATURES WILL REMAIN 10 DEGREES ABOVE NORMAL THROUGH MUCH OF THE PERIOD UNDER THE UPPER LEVEL RIDGE AND SOUTHERLY FLOW. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... WITH THE UPPER LOW STILL CENTERED OVER THE GREAT LAKES...PERIODS OF SHOWERS AND VARIABLE STRATOCUMULUS WILL CONTINUE TO PLAGUE THE TAF SITES TODAY. PREVAILING MVFR CIGS COULD RAISE TO VFR OCCASIONALLY THIS AFTERNOON. SURFACE WINDS WILL BE FROM THE SOUTHWEST AROUND 10 KTS...BUT GUSTS TO 20-25 KTS ARE POSSIBLE THIS AFTERNOON. WIND SPEEDS WILL LOWER TO NEAR 5 KTS LATE TONIGHT. AS UPPER LEVEL LOW CENTER EXITS EAST TONIGHT...THE STRATOCUMULUS MAY BECOME SCATTERED. HOWEVER...IF THIS HAPPENS...NOCTURNAL COOLING WILL INCREASE...AND THIS MAY HELP FORM LATE NIGHT MVFR STRATUS AND FOG. REGARDLESS OF ANY LATE NIGHT STRATUS/FOG FORMATION...THESE CLOUDS WILL EITHER DISSIPATE OR LIFT TO VFR CUMULUS BY LATE MORNING...AS HIGH PRESSURE SUBSIDENCE AND DRYING BEGIN. .OUTLOOK.../SUNDAY NIGHT THROUGH WEDNESDAY/... VFR INTO AT LEAST TUESDAY...AND PERHAPS WEDNESDAY DUE TO UNCERTAINTIES REGARDING TRACK OF NEXT LOW PRESSURE SYSTEM AND ITS IMPACTS ON THE UPPER OHIO VALLEY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
709 AM EDT SAT OCT 20 2012 .SYNOPSIS... A LARGE UPPER LEVEL LOW CENTER WILL SLOWLY MOVE EASTWARD THROUGH THE GREAT LAKES TODAY...AND PROVIDE THE UPPER OHIO VALLEY WITH CLOUDS... SHOWERS AND COOLER TEMPERATURES. HIGH PRESSURE WILL BUILD IN LATER SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... BLEND OF RECENT SREF AND RAP MODEL OUTPUT...CONFIRMED BY RECENT SURFACE...RADAR...AND SATELLITE DATA...SHOW AN UPPER LEVEL LOW WILL ROTATE EASTWARD THROUGH THE GREAT LAKES TODAY...AND CAUSE CLOUDY SKIES AND SCATTERED SHOWERS ACROSS THE UPPER OHIO VALLEY. SURFACE WINDS CAN GUST UP TO 25 MPH THIS AFTERNOON. ANY REMAINING SHOWERS SHOULD DISSIPATE BY MIDNIGHT. CONTINUED TO FORECAST MOSTLY CLOUDY SKIES...BUT TREND IN RECENT GFS AND NAM MOS SUGGEST CLOUDS COULD BREAK UP OVERNIGHT. HOWEVER IF THIS HAPPENS...ITS POSSIBLE THERE CAN BE PATCHY FOG FORMING LATE TONIGHT. FOR NOW...INCLUDED ISOLATED RIVER VALLEY FOG PATCHES SOUTH AND WEST OF PITTSBURGH NEAR DAWN SUNDAY. FORECASTED HIGH TEMPERATURES TODAY AND LOWS TONIGHT TO BE UP TO 5 DEGREES COOLER THAN NORMAL...PER RECENT GFS AND NAM MOS. && .SHORT TERM /SUNDAY THROUGH MONDAY/... 50H LOW WILL PICK UP SPEED AND MOVE ACROSS NEW ENGLAND ON SUNDAY. ALTHOUGH THE CORE OF THE SYSTEM WILL BE WELL TO THE NORTH...FLOW IN THE MID AN UPPER LEVELS WILL REMAIN CYCLONIC. BECAUSE OF THE AFOREMENTIONED FLOW AND COOLER AIR ALOFT...THINK THAT CLOUDS WILL HOLD AT LEAST INTO SUNDAY AFTERNOON. THE EXTRA CLOUD COVER WILL ALSO KEEP TEMPS BELOW GUIDANCE. MID AND LOW LEVEL WAA BEGINS TO INCREASE SUNDAY NIGHT...AND A SURFACE HIGH WILL MOVE ACROSS THE MID-ATLANTIC. SKIES WILL CLEAR SUNDAY NIGHT. SFC HIGH WILL MOVE VERY LITTLE ON MONDAY...AS UPPER LEVEL RIDGE MOVES OVER OHIO. EXPECT SUNSHINE ON MONDAY WITH NEAR NORMAL TEMPS. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... THE MODELS GENERALLY AGREE THAT AN UPPER LEVEL RIDGE WILL BE IN PLACE OVER MUCH OF THE CENTRAL-EASTERN HALF OF THE US FOR THE START OF THE PERIOD. WHAT REMAINS A BIT MORE INCONSISTENT ARE THE TIMING AND STRENGTH OF THE SYSTEMS THAT DEVELOP AND ATTEMPT TO BREAK DOWN THE RIDGE LATER TUESDAY/WEDNESDAY AND THE TIMING OF THE EVENTUAL COLD FRONT SUGGESTED BY BOTH THE GFS/ECMWF FOR FRIDAY. THE GFS TENDS TO BE A BIT FASTER WITH THE WARM-FRONTAL SHOWERS TUESDAY AFTERNOON/EVENING THAN THE ECMWF...WHICH HAS A STRONGER HIGH PRESSURE RIDGE AND KEEPS MORE OF THE MOISTURE NORTH. AT THIS POINT...WILL MAINTAIN A FORECAST CLOSE TO HPC VALUES FOR POPS. BOTH MODELS AND ENSEMBLE MEANS/MOS GUIDANCE SUGGEST THAT TEMPERATURES WILL REMAIN 10 DEGREES ABOVE NORMAL THROUGH MUCH OF THE PERIOD UNDER THE UPPER LEVEL RIDGE AND SOUTHERLY FLOW. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... PER RECENT SURFACE AND RADAR DATA...COUPLED WITH RECENT RAP MODEL OUTPUT AND GFS LAMP AND NAM MOS...EXPECT MAINLY MVFR STRATOCUMULUS CEILINGS TODAY. VISIBILITIES MAY BRIEFLY BECOME MVFR IN PASSING SCATTERED SHOWERS. SURFACE WINDS WILL BE FROM THE SOUTHWEST AROUND 10 KTS...BUT GUSTS TO 20-25 KTS ARE POSSIBLE THIS AFTERNOON. WIND SPEEDS WILL LOWER TO NEAR 5 KTS LATE TONIGHT. AS CAUSATIVE UPPER LEVEL LOW CENTER EXITS EAST TONIGHT...THE STRATOCUMULUS MAY BECOME SCATTERED. HOWEVER...IF THIS HAPPENS...NOCTURNAL COOLING WILL INCREASE...AND THIS MAY HELP FORM LATE NIGHT MVFR STRATUS AND FOG. REGARDLESS OF ANY LATE NIGHT STRATUS/FOG FORMATION...THESE CLOUDS WILL EITHER DISSIPATE OR LIFT TO VFR CUMULUS BY LATE MORNING...AS HIGH PRESSURE SUBSIDENCE AND DRYING BEGIN. .OUTLOOK.../SUNDAY NIGHT THROUGH WEDNESDAY/... VFR INTO AT LEAST TUESDAY...AND PERHAPS WEDNESDAY DUE TO UNCERTAINTIES REGARDING TRACK OF NEXT LOW PRESSURE SYSTEM AND ITS IMPACTS ON THE UPPER OHIO VALLEY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
651 AM EDT SAT OCT 20 2012 .SYNOPSIS... AN UPPER LEVEL LOW PRESSURE SYSTEM ACROSS THE GREAT LAKES WILL CONTINUE TO MOVE NORTHEAST AWAY FROM THE REGION TODAY. HIGH PRESSURE WILL BUILD IN ITS WAKE TONIGHT INTO SUNDAY. THE HIGH WILL CONTINUE TO INFLUENCE THE REGION THROUGH EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AN UPPER LEVEL CLOSED LOW CENTERED OVER SRN MICHIGAN THIS MORNING WILL CONTINUE TO MOVE NORTHEAST AWAY FROM THE REGION TODAY. IN THE MEANTIME...AN EMBEDDED VORT LOBE ROTATING AROUND THE LOW WILL QUICKLY MOVE EAST ACRS THE REGION EARLY THIS MORNING. MOSAIC RADAR DEPICTED AN AREA OF SHOWERS IN ASSOCIATION WITH THIS FEATURE... WHICH WAS MOVING INTO THE WHITEWATER AND MIAMI VALLEYS. AM EXPECTING THESE SHOWERS TO HOLD TOGETHER LONG ENOUGH FOR LIKELY POPS ACRS THE WHITEWATER AND MIAMI VALLEYS (DAYTON AREA) WITH A WEAKENING TREND AS IT SHIFTS TOWARD CENTRAL OHIO BY SUNRISE PER THE HRRR MODEL. OTHERWISE...THE REMAINDER OF THE DAY WILL EXHIBIT LOW CHANCE POPS DUE TO WEAK DAYTIME INSTABILITY WITH THE THREAT OF RAIN COMING TO AN END BY THIS EVENING. MOSTLY CLOUDY SKIES WILL BEGIN TO PARTIALLY CLEAR LATE IN THE DAY. HIGHS TODAY WILL REMAIN BELOW NORMAL...PEAKING INTO THE LOWER AND MID 50S. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... SURFACE HIGH PRESSURE IS EXPECTED TO BUILD INTO THE OHIO VALLEY FROM THE SOUTHWEST TONIGHT. SKIES WILL CLEAR...AND WITH WINDS BECOMING LIGHT...SOME FROST FORMATION IS EXPECTED. PARTS OF THE AREA REMAIN IN THE FROST/FREEZE PROGRAM AND HAVE ISSUED A FROST ADVISORY FOR THESE LOCATIONS. LOWS WILL GENERALLY FALL INTO THE MID AND UPPER 30S...BUT A FEW LOWER 30S CAN NOT BE RULED OUT. SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION ON SUNDAY. WITH AMPLE SUNSHINE AND A MODIFYING AIRMASS...TEMPERATURES WILL WARM INTO THE LOWER AND MID 60S...WHICH IS ABOUT NORMAL FOR THIS TIME OF THE YEAR. FOR THE PERIOD SUNDAY NIGHT INTO MONDAY...CENTER OF THE SURFACE HIGH WILL MOVE TO A POSITION OVER THE MID ATLANTIC/SE U.S. MODELS CONTINUE TO INDICATE THAT ALTHOUGH A MID LVL RIDGE WILL BUILD ACRS THE REGION...IT WILL BE RELATIVELY FLAT IN AMPLITUDE...AND AS SUCH...WILL ALLOW FOR WEAK FEATURES TO MOVE THROUGH IT. ONE SUCH FEATURE IS EXPECTED TO BRUSH BY OUR NW MONDAY AFTERNOON INTO MONDAY EVENING. AT THIS TIME...HAVE INCREASED CLOUDS ACRS THE REGION...ESPECIALLY NORTHWEST...AND HAVE KEPT THE THREAT FOR SHOWERS JUST OUTSIDE OUR AREA. THE AIRMASS WILL CONTINUE TO WARM AND WITH A SOUTHERLY FLOW...TEMPERATURES WILL RISE INTO THE LOWER AND MID 70S. FOR MONDAY NIGHT INTO TUESDAY NIGHT...ANOTHER WEAK DISTURBANCE IS FORECAST TO MOVE THROUGH THE RIDGE. THIS FEATURE WILL COMBINE WITH SOME ISENTROPIC LIFT TO BRING A THREAT FOR A FEW SHOWERS TO OUR NWRN ZONES...PARTICULARLY MONDAY NIGHT INTO TUESDAY. OTHER LOCATIONS WILL GENERALLY SEE PARTLY CLOUDY CONDITIONS. && .LONG TERM /WEDNESDAY THROUGH FRIDAY/... MID LEVEL RIDGE WILL REBOUND ON WEDNESDAY AHEAD OF THE NEXT WEATHER SYSTEM TO AFFECT THE REGION BY THE END OF THE WEEK. ABOVE NORMAL TEMPERATURES WILL CONTINUE. A COLD FRONT WILL APPROACH AND MOVE THROUGH THE AREA THURSDAY NIGHT INTO FRIDAY. AFTER THE FRONT MOVES THROUGH HIGH TEMPERATURES ON FRIDAY WILL BE IN THE MIDDLE 60S TO AROUND 70. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... A LARGE AREA OF LOW PRESSURE WILL CONTINUE TO MOVE NORTHEAST AWAY FROM THE REGION TODAY. BEHIND THE LOW...THERE IS STILL A CONSIDERABLE AMOUNT OF LOW LEVEL MOISTURE...LEADING TO A DIFFICULT SET OF TAFS FOR THE FIRST 6-12 HOURS. RAIN SHOWERS WILL CONTINUE MOVING THROUGH CENTRAL OHIO THIS MORNING...IMPACTING THE COLUMBUS TAF SITES. MEANWHILE...MOISTURE HAS BECOME THICKER NEAR THE SURFACE OVER INDIANA OVER THE PAST FEW HOURS. THIS HAS LED WIDESPREAD CEILINGS THAT ARE STRADDLING THE MVFR/IFR THRESHOLD...AND SOME IFR CONDITIONS ARE EXPECTED FOR THE NORTHERN TAF SITES THIS MORNING. THIS FORECAST WILL SLOW DOWN THE IMPROVEMENT OVER THE COURSE OF THE DAY...WITH NEW MODEL DATA INDICATING THAT MOSITURE WILL BE SLOW TO SCOUR OUT. A FEW LIGHT SHOWERS ARE POSSIBLE IN CENTRAL OHIO (KCMH/KLCK) DURING THE PEAK HEATING HOURS OF THE AFTERNOON...BUT CONFIDENCE IN TIMING AND PLACEMENT IS LOW. FOG POTENTIAL ON SUNDAY MORNING IS ALSO A SIGNIFICANT FORECAST QUESTION. IF CLOUDS ARE ABLE TO CLEAR OUT...CONDITIONS WILL CERTAINLY SUPPORT FOG DEVELOPMENT. .OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...FROST ADVISORY FROM 2 AM TO 9 AM EDT SUNDAY FOR OHZ046-055-061- 062-064-070-071-077>079. KY...FROST ADVISORY FROM 2 AM TO 9 AM EDT SUNDAY FOR KYZ089>099. IN...FROST ADVISORY FROM 2 AM TO 9 AM EDT SUNDAY FOR INZ073>075-080. && $$ SYNOPSIS...HICKMAN NEAR TERM...HICKMAN SHORT TERM...HICKMAN LONG TERM...HICKMAN/NOVAK AVIATION...HATZOS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
236 PM MDT SAT OCT 20 2012 .UPDATE... ISSUED AT 140 PM MDT SAT OCT 20 2012 EARLIER SENT OUT ANOTHER UPDATE. TODAYS MAXES APPROACHING FORECAST MAXES WITH ANOTHER HOUR OR TWO OF HEATING. UPDATE ISSUED AT 1038 AM MDT SAT OCT 20 2012 TEMPERATURES RESPONDING VERY WELL WITH DOWNSLOPE WINDS AND DRY AIR MASS PLACE...ESPECIALLY IN THE WESTERN PORTION OF THE AREA. RUC IS NOT ONLY CATCHING THE WARM UP WELL BUT ALSO THE WIND FIELD THE BEST AS WELL. NAM IS ALSO CATCHING THE WARMUP AS WELL. SO PER THAT DATA COMPARED TO THE RECENT OBSERVATIONAL TRENDS...RAISED THE MAXES 3 TO 5 DEGREES. OTHERWISE...JUST ADJUSTED THE TRENDS ON THE HOURLY GRIDS. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 147 PM MDT SAT OCT 20 2012 MODELS HAVING A HARD TIME RESOLVING THE TEMPERATURE AND WIND FIELD FOR THE CURRENT PERIOD. THIS ALONG WITH ANOTHER EXPECTED VARIABLE WIND FIELD TONIGHT MAKE FOR A COMPLICATED MIN FORECAST. THERE WAS A WIDE RANGE IN LOWS LAST NIGHT. USED A BLEND OF THE RUC AND NAM FOR THE WINDS. SHOULD GET WARM AIR ADVECTION OVER THE FORECAST AREA BEFORE THE PREFRONTAL TROUGH AND THEN COLD FRONT START MOVING THROUGH. EXPECT ONCE AGAIN WHERE THE TROUGH LINE IS WILL BE WHERE COOLEST MINS SHOULD BE BUT DO EXPECT A WIDE RANGE ONCE AGAIN BUT A LITTLE WARMER THAN LAST NIGHT. MODELS DIFFERING ON THE ARRIVAL OF THE NEXT COLD FRONT WHICH DOES NOT LOOK TOO STRONG. MODELS HAVE TENDED TO SLOW THIS DOWN AND LOOKS TO NOT BE THROUGH THE ENTIRE FORECAST AREA BY THE END OF MAX HEATING TIME. THERE IS A 5 TO NEARLY 10 DEGREE DIFFERENCE IN MAXES. USING A CLUSTER OF THE BEST RECENT PERFORMING GUIDANCE...2 METER AND 850 MB TEMPERATURE BIASES SUPPORT A LITTLE WARMER MAXES...ESPECIALLY IN THE SOUTHEAST HALF OF THE AREA. IT DOES LOOK LIKE A BIG GRADIENT ACROSS THE AREA RANGING FROM THE MIDDLE TO UPPER 60S IN THE NORTHWEST CORNER TO THE LOWER 80S IN THE SOUTHEAST. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 235 PM MDT SAT OCT 20 2012 FOR SUNDAY NIGHT THROUGH MONDAY NIGHT...THE COLD FRONT WILL EXIT THE AREA SUNDAY EVENING. MEANWHILE A CLOSED LOW WILL REMAIN ANCHORED JUST OFF THE COAST OF THE PACIFIC NORTHWEST...WITH SOUTHWEST FLOW ALOFT AND NUMEROUS SHORT WAVE TROUGHS MOVING OVER THE AREA. THE STRONGEST UPPER LEVEL DISTURBANCE WILL BE THE REMNANTS OF THE STORM SYSTEM CURRENTLY WEST OF BAJA CALIFORNIA...WHICH WILL APPROACH THE AREA OVERNIGHT SUNDAY NIGHT/MONDAY MORNING. AHEAD OF THE DISTURBANCE NAM/SREF SHOW SOME WEAK ISENTROPIC LIFT OVER THE FAR EASTERN PART OF THE AREA AROUND 850 TO 880MB. HOWEVER IT IS VERY SHALLOW SO WILL ONLY HAVE SILENT CHANCES IN FOR THOSE PERIODS FOR THE FAR EAST. OTHERWISE AM NOT EXPECTING AN PRECIPITATION OVER THE AREA DURING THIS TIME FRAME DUE TO THE A DRY AIR MASS IN PLACE. FOR TUESDAY THROUGH SATURDAY...THE MAJORITY OF THE PERIOD WILL REMAIN DRY. THE CLOSED LOW OFF THE COAST OF THE PACIFIC NORTHWEST WILL MOVE ONSHORE WEDNESDAY NIGHT. MODELS DISAGREE WITH THE DEVELOPMENT OF THE CLOSED LOW ONCE IT MOVES ON SHORE. THE GFS/DGEX/UKMET/GEM DIVE THE CLOSED LOW SOUTH AT VARYING SPEEDS BEHIND A COLD FRONT...WHILE THE 0Z ECMWF HAS A SHORT WAVE TROUGH KICK OUT OF THE CLOSED LOW BEFORE IT MOVES ONSHORE...KEEPING BOTH FURTHER NORTH ALONG THE US/CANADIAN BORDER. MEANWHILE THE GFS HAS A COLD FRONT MOVING THROUGH WEDNESDAY NIGHT...AND DEPENDING ON THE MODEL OF CHOICE...EITHER THE LEFT EXIT OR RIGHT ENTRANCE OF THE 500MB JET OVER THE NORTHERN HALF OF THE AREA. DESPITE THE MODEL DISAGREEMENT CONSENSUS HAS PRECIP CHANCES OVER THE NORTHERN HALF OF THE AREA...WHICH SEEMS REASONABLE. ON A SIDE NOTE THE 12Z ECMWF IS NOW IN LINE WITH THE OTHER MODELS REGARDING THE TRACK OF THE CLOSED LOW AND FRONTAL PASSAGE...GIVING MORE WEIGHT TO THE NOTION OF PRECIP CHANCES WEDNESDAY NIGHT. TEMPERATURES FOR THE PERIOD WILL BE WELL ABOVE NORMAL TUESDAY...TRANSITIONING TO BELOW NORMAL BEHIND THE COLD FRONT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1142 AM MDT SAT OCT 20 2012 VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. MODELS ARE HAVE A HARD TIME RESOLVING THE WIND FIELD AS SEVERAL SMALL SCALE SHORTWAVE TROUGHS MOVE THROUGH IN THE WESTERLY FLOW ALOFT. NUMBER OF WIND SHIFT LINES ASSOCIATED WITH THOSE MID LEVEL FEATURES. AT THIS TIME NAM AND RUC LOOK TO BE DEPICTING THIS THE BEST. AS A RESULT WINDS WILL BE SHIFTING THROUGH TONIGHT AS A RESULT OF THESE PROGRESSIVE SURFACE TROUGHS. A FRONT MOVES INTO THE AREA BETWEEN 12Z AND 15Z TOMORROW. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...BULLER LONG TERM...JTL AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
203 PM MDT SAT OCT 20 2012 .UPDATE... ISSUED AT 140 PM MDT SAT OCT 20 2012 EARLIER SENT OUT ANOTHER UPDATE. TODAYS MAXES APPROACHING FORECAST MAXES WITH ANOTHER HOUR OR TWO OF HEATING. UPDATE ISSUED AT 1038 AM MDT SAT OCT 20 2012 TEMPERATURES RESPONDING VERY WELL WITH DOWNSLOPE WINDS AND DRY AIR MASS PLACE...ESPECIALLY IN THE WESTERN PORTION OF THE AREA. RUC IS NOT ONLY CATCHING THE WARM UP WELL BUT ALSO THE WIND FIELD THE BEST AS WELL. NAM IS ALSO CATCHING THE WARMUP AS WELL. SO PER THAT DATA COMPARED TO THE RECENT OBSERVATIONAL TRENDS...RAISED THE MAXES 3 TO 5 DEGREES. OTHERWISE...JUST ADJUSTED THE TRENDS ON THE HOURLY GRIDS. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 147 PM MDT SAT OCT 20 2012 MODELS HAVING A HARD TIME RESOLVING THE TEMPERATURE AND WIND FIELD FOR THE CURRENT PERIOD. THIS ALONG WITH ANOTHER EXPECTED VARIABLE WIND FIELD TONIGHT MAKE FOR A COMPLICATED MIN FORECAST. THERE WAS A WIDE RANGE IN LOWS LAST NIGHT. USED A BLEND OF THE RUC AND NAM FOR THE WINDS. SHOULD GET WARM AIR ADVECTION OVER THE FORECAST AREA BEFORE THE PREFRONTAL TROUGH AND THEN COLD FRONT START MOVING THROUGH. EXPECT ONCE AGAIN WHERE THE TROUGH LINE IS WILL BE WHERE COOLEST MINS SHOULD BE BUT DO EXPECT A WIDE RANGE ONCE AGAIN BUT A LITTLE WARMER THAN LAST NIGHT. MODELS DIFFERING ON THE ARRIVAL OF THE NEXT COLD FRONT WHICH DOES NOT LOOK TOO STRONG. MODELS HAVE TENDED TO SLOW THIS DOWN AND LOOKS TO NOT BE THROUGH THE ENTIRE FORECAST AREA BY THE END OF MAX HEATING TIME. THERE IS A 5 TO NEARLY 10 DEGREE DIFFERENCE IN MAXES. USING A CLUSTER OF THE BEST RECENT PERFORMING GUIDANCE...2 METER AND 850 MB TEMPERATURE BIASES SUPPORT A LITTLE WARMER MAXES...ESPECIALLY IN THE SOUTHEAST HALF OF THE AREA. IT DOES LOOK LIKE A BIG GRADIENT ACROSS THE AREA RANGING FROM THE MIDDLE TO UPPER 60S IN THE NORTHWEST CORNER TO THE LOWER 80S IN THE SOUTHEAST. .LONG TERM...(TUESDAY THROUGH FRIDAY) ISSUED AT 248 AM MDT SAT OCT 20 2012 NUMERICAL GUIDANCE IS IN DECENT AGREEMENT THROUGH 12Z TUESDAY...AT WHICH TIME SIGNIFICANT DIFFERENCES OCCUR...LEADING TO LOW CONFIDENCE IN THE EXTENDED PERIOD ESPECIALLY IN THE THU-FRI TIME FRAME. GFS IS MUCH MORE AGGRESSIVE IN BRINGING A STRONG TROUGH/UPPER JET INTO THE CENTRAL ROCKIES AFTER MID-WEEK WHILE THE EC BRINGS THESE FEATURES ACROSS THE NORTHERN ROCKIES/NORTHERN PLAINS. BOTH MODELS DO PUSH A COLD FRONT THROUGH THE AREA WEDNESDAY BUT THE SFC EVOLUTION AFTER THAT DIFFERS MARKEDLY. AS A RESULT KEPT THE ALL-BLEND INIT FOR THE EXTENDED PERIOD WITH MINIMAL CHANGES. IN TERMS OF SENSIBLE WEATHER...CURRENT FORECAST SHOWS A CONTINUATION OF UNSEASONABLY WARM TEMPERATURES THROUGH TUESDAY WITH HIGHS NEAR 80...BUT BY THU-FRI HIGHS IN THE 50S ARE FORECAST. KEPT THE CHANCE OF SHOWERS GOING WEDNESDAY NIGHT FOR NOW WITH BOTH GFS/EC SHOWING AN UPPER TROUGH PASSAGE AND DECENT JET SUPPORT AT 250 MB. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1142 AM MDT SAT OCT 20 2012 VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. MODELS ARE HAVE A HARD TIME RESOLVING THE WIND FIELD AS SEVERAL SMALL SCALE SHORTWAVE TROUGHS MOVE THROUGH IN THE WESTERLY FLOW ALOFT. NUMBER OF WIND SHIFT LINES ASSOCIATED WITH THOSE MID LEVEL FEATURES. AT THIS TIME NAM AND RUC LOOK TO BE DEPICTING THIS THE BEST. AS A RESULT WINDS WILL BE SHIFTING THROUGH TONIGHT AS A RESULT OF THESE PROGRESSIVE SURFACE TROUGHS. A FRONT MOVES INTO THE AREA BETWEEN 12Z AND 15Z TOMORROW. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...BULLER LONG TERM...DLF AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1145 AM MDT SAT OCT 20 2012 .UPDATE... ISSUED AT 1038 AM MDT SAT OCT 20 2012 TEMPERATURES RESPONDING VERY WELL WITH DOWNSLOPE WINDS AND DRY AIR MASS PLACE...ESPECIALLY IN THE WESTERN PORTION OF THE AREA. RUC IS NOT ONLY CATCHING THE WARM UP WELL BUT ALSO THE WIND FIELD THE BEST AS WELL. NAM IS ALSO CATCHING THE WARMUP AS WELL. SO PER THAT DATA COMPARED TO THE RECENT OBSERVATIONAL TRENDS...RAISED THE MAXES 3 TO 5 DEGREES. OTHERWISE...JUST ADJUSTED THE TRENDS ON THE HOURLY GRIDS. && .SHORT TERM...(TODAY THROUGH MONDAY NIGHT) ISSUED AT 248 AM MDT SAT OCT 20 2012 WESTERLY FLOW WILL CONTINUE ACROSS THE CENTRAL PLAINS THROUGH TONIGHT TRANSITIONING TO SOUTHWESTERLY FLOW SUNDAY AHEAD OF A TROUGH OVER THE DESERT SOUTHWEST. THE TROUGH WILL MOVE NORTHEAST AND MOVE INTO SOUTHWEST KANSAS MONDAY. SOUTHWEST FLOW WILL CONTINUE MONDAY NIGHT BEHIND THE EXITING TROUGH. A SURFACE TROUGH OVER EASTERN COLORADO WILL EVENTUALLY MOVE EAST ACROSS NORTHWEST KANSAS SUNDAY NIGHT. HIGH PRESSURE WILL BUILD INTO NORTHWEST KANSAS MONDAY AND MONDAY NIGHT. SHORTWAVE ENERGY MOVES THROUGH SOUTHWEST FLOW INTO WESTERN KANSAS SUNDAY. HOWEVER, MOISTURE IS MEAGER SO WILL KEEP POPS NIL. ALL OTHER PERIODS LOOK DRY WITH SUBSIDENCE AND LACK OF MOISTURE. ABOVE NORMAL TEMPERATURES IN THE LOWER 80S ARE EXPECTED TODAY. COOLER READINGS IN THE UPPER 60S AND 70S WILL OCCUR SUNDAY AND MONDAY. MIN TEMPERATURES WILL BE IN THE 40S. .LONG TERM...(TUESDAY THROUGH FRIDAY) ISSUED AT 248 AM MDT SAT OCT 20 2012 NUMERICAL GUIDANCE IS IN DECENT AGREEMENT THROUGH 12Z TUESDAY...AT WHICH TIME SIGNIFICANT DIFFERENCES OCCUR...LEADING TO LOW CONFIDENCE IN THE EXTENDED PERIOD ESPECIALLY IN THE THU-FRI TIME FRAME. GFS IS MUCH MORE AGGRESSIVE IN BRINGING A STRONG TROUGH/UPPER JET INTO THE CENTRAL ROCKIES AFTER MID-WEEK WHILE THE EC BRINGS THESE FEATURES ACROSS THE NORTHERN ROCKIES/NORTHERN PLAINS. BOTH MODELS DO PUSH A COLD FRONT THROUGH THE AREA WEDNESDAY BUT THE SFC EVOLUTION AFTER THAT DIFFERS MARKEDLY. AS A RESULT KEPT THE ALL-BLEND INIT FOR THE EXTENDED PERIOD WITH MINIMAL CHANGES. IN TERMS OF SENSIBLE WEATHER...CURRENT FORECAST SHOWS A CONTINUATION OF UNSEASONABLY WARM TEMPERATURES THROUGH TUESDAY WITH HIGHS NEAR 80...BUT BY THU-FRI HIGHS IN THE 50S ARE FORECAST. KEPT THE CHANCE OF SHOWERS GOING WEDNESDAY NIGHT FOR NOW WITH BOTH GFS/EC SHOWING AN UPPER TROUGH PASSAGE AND DECENT JET SUPPORT AT 250 MB. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1142 AM MDT SAT OCT 20 2012 VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. MODELS ARE HAVE A HARD TIME RESOLVING THE WIND FIELD AS SEVERAL SMALL SCALE SHORTWAVE TROUGHS MOVE THROUGH IN THE WESTERLY FLOW ALOFT. NUMBER OF WIND SHIFT LINES ASSOCIATED WITH THOSE MID LEVEL FEATURES. AT THIS TIME NAM AND RUC LOOK TO BE DEPICTING THIS THE BEST. AS A RESULT WINDS WILL BE SHIFTING THROUGH TONIGHT AS A RESULT OF THESE PROGRESSIVE SURFACE TROUGHS. A FRONT MOVES INTO THE AREA BETWEEN 12Z AND 15Z TOMORROW. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...FS LONG TERM...DLF AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1044 AM MDT SAT OCT 20 2012 .UPDATE... ISSUED AT 1038 AM MDT SAT OCT 20 2012 TEMPERATURES RESPONDING VERY WELL WITH DOWNSLOPE WINDS AND DRY AIR MASS PLACE...ESPECIALLY IN THE WESTERN PORTION OF THE AREA. RUC IS NOT ONLY CATCHING THE WARM UP WELL BUT ALSO THE WIND FIELD THE BEST AS WELL. NAM IS ALSO CATCHING THE WARMUP AS WELL. SO PER THAT DATA COMPARED TO THE RECENT OBSERVATIONAL TRENDS...RAISED THE MAXES 3 TO 5 DEGREES. OTHERWISE...JUST ADJUSTED THE TRENDS ON THE HOURLY GRIDS. && .SHORT TERM...(TODAY THROUGH MONDAY NIGHT) ISSUED AT 248 AM MDT SAT OCT 20 2012 WESTERLY FLOW WILL CONTINUE ACROSS THE CENTRAL PLAINS THROUGH TONIGHT TRANSITIONING TO SOUTHWESTERLY FLOW SUNDAY AHEAD OF A TROUGH OVER THE DESERT SOUTHWEST. THE TROUGH WILL MOVE NORTHEAST AND MOVE INTO SOUTHWEST KANSAS MONDAY. SOUTHWEST FLOW WILL CONTINUE MONDAY NIGHT BEHIND THE EXITING TROUGH. A SURFACE TROUGH OVER EASTERN COLORADO WILL EVENTUALLY MOVE EAST ACROSS NORTHWEST KANSAS SUNDAY NIGHT. HIGH PRESSURE WILL BUILD INTO NORTHWEST KANSAS MONDAY AND MONDAY NIGHT. SHORTWAVE ENERGY MOVES THROUGH SOUTHWEST FLOW INTO WESTERN KANSAS SUNDAY. HOWEVER, MOISTURE IS MEAGER SO WILL KEEP POPS NIL. ALL OTHER PERIODS LOOK DRY WITH SUBSIDENCE AND LACK OF MOISTURE. ABOVE NORMAL TEMPERATURES IN THE LOWER 80S ARE EXPECTED TODAY. COOLER READINGS IN THE UPPER 60S AND 70S WILL OCCUR SUNDAY AND MONDAY. MIN TEMPERATURES WILL BE IN THE 40S. .LONG TERM...(TUESDAY THROUGH FRIDAY) ISSUED AT 248 AM MDT SAT OCT 20 2012 NUMERICAL GUIDANCE IS IN DECENT AGREEMENT THROUGH 12Z TUESDAY...AT WHICH TIME SIGNIFICANT DIFFERENCES OCCUR...LEADING TO LOW CONFIDENCE IN THE EXTENDED PERIOD ESPECIALLY IN THE THU-FRI TIME FRAME. GFS IS MUCH MORE AGGRESSIVE IN BRINGING A STRONG TROUGH/UPPER JET INTO THE CENTRAL ROCKIES AFTER MID-WEEK WHILE THE EC BRINGS THESE FEATURES ACROSS THE NORTHERN ROCKIES/NORTHERN PLAINS. BOTH MODELS DO PUSH A COLD FRONT THROUGH THE AREA WEDNESDAY BUT THE SFC EVOLUTION AFTER THAT DIFFERS MARKEDLY. AS A RESULT KEPT THE ALL-BLEND INIT FOR THE EXTENDED PERIOD WITH MINIMAL CHANGES. IN TERMS OF SENSIBLE WEATHER...CURRENT FORECAST SHOWS A CONTINUATION OF UNSEASONABLY WARM TEMPERATURES THROUGH TUESDAY WITH HIGHS NEAR 80...BUT BY THU-FRI HIGHS IN THE 50S ARE FORECAST. KEPT THE CHANCE OF SHOWERS GOING WEDNESDAY NIGHT FOR NOW WITH BOTH GFS/EC SHOWING AN UPPER TROUGH PASSAGE AND DECENT JET SUPPORT AT 250 MB. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 440 AM MDT SAT OCT 20 2012 VFR CONDITIONS WILL PERSIST OVER THE NEXT 24 HOURS AT KGLD AND KMCK. LIGHT SOUTHWEST WINDS WILL PRECEDE A TROUGH IN EASTERN COLORADO. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...FS LONG TERM...DLF AVIATION...FS
AREA FORECAST DISCUSSION
NWS JACKSON KY
135 PM EDT SAT OCT 20 2012 .UPDATE... ISSUED AT 950 AM EDT SAT OCT 20 2012 THE FORECAST APPEARS TO BE ON TRACK THIS MORNING WITH MINIMAL TWEAKS TO HOURLY TEMPS AND DEW PTS. LOOKING AT THE FIRST ECHOS OF THE DAY DRIFTING THROUGH FLEMING AND ROWAN COUNTIES IT IS APPARENT THAT LITTLE IF ANY OF THIS IS REACHING THE GROUND AND WILL CONTINUE WITH THE IDEA OF SCATTERED SPRINKLES THROUGH THE DAY PRIMARILY ALONG AND NORTH OF THE MOUNTAIN PARKWAY. ZONES AND HWO LOOK GOOD...AND NO UPDATE APPEARS TO BE NEEDED THERE ATTM. UPDATE ISSUED AT 724 AM EDT SAT OCT 20 2012 TEMPERATURES HAVE STAYED UP IN THE MID AND UPPER 40S THIS MORNING DUE TO THE EXTENSIVE CLOUD COVER. HAVE FRESHENED UP THE FORECAST GRIDS TO RESEMBLE THIS. OTHERWISE...THE FORECAST IS GOOD TO GO. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 346 AM EDT SAT OCT 20 2012 CURRENT CONDITIONS ACROSS EASTERN KENTUCKY FEATURE AN UPPER LEVEL LOW CENTERED OVER MI KEEPING CONTINUED CLOUD COVER OVER THE OHIO VALLEY. THEREFORE...THIS WILL KEEP MORNING TEMPERATURES WARM IN THE MID 40S. WITH THE HEATING OF DAY AND AT LEAST A TAD OF INSTABILITY AND THE UPPER LEVEL LOW PROVIDING SEVERAL WEAK VORT MAXES MOVING THROUGH...WILL KEEP ISOLATED SPRINKLES ACROSS THE AREA THROUGH THE AFTERNOON...MAINLY ALONG AND NORTH OF THE MOUNTAIN PARKWAY. GIVEN THE CURRENT TREND OF THE MODELS...WILL LEAN TOWARD A SLOWER EXIT OF THE UPPER LOW TO THE NORTHEAST. THEREFORE...KEEPING HIGH TEMPS FOR TODAY TEMPERED TO THE UPPER 50S. LOCALES SUCH AS BLACK MOUNTAIN WILL STRUGGLE TO REACH THE MID 40S. HEADING INTO TONIGHT...THE FORECAST CHALLENGE ARISES...AS THE NAM AND RUC HINT AT THE UPPER LOW AND ASSOCIATED 850 MOISTURE/CLOUD COVER FINALLY EXITING TO THE NORTHEAST. THIS PROCESS CONTINUING THROUGH TONIGHT WILL SLOWLY ALLOW CLEARING FROM THE SOUTHWEST TO THE NORTHEAST. SO HAVE TRIED TO SHOW THIS IN THE SUN NIGHT MIN TEMPS AS STATIONS SUCH AS MONTICELLO COULD BOTTOM OUT INTO THE MID 30S TONIGHT. SO WENT WITH A SIGNIFICANT RIDGE VALLEY SPLIT WHERE AREAS WILL CLEAR OUT ALONG WITH A GENERAL GRADIENT WITH THE SOUTHWEST BEING COOLER TO THE NORTHEAST BEING WARMER AS THE CLOUD COVER EXITS. THIS WILL ALSO ALLOW FOR SOME EXTENSIVE FOG DEVELOPMENT TONIGHT ESPECIALLY WHERE AREAS CLEAR OUT. THE COLDEST LOCATIONS WILL ALSO SEE SOME PATCHY FROST. FOR SUNDAY...CLOUD COVER IS EXPECT TO CLEAR OUT WITH A SHORTWAVE RIDGE OVERHEAD AND AN OVERALL GREAT WEATHER DAY WITH LIGHT SOUTHERLY WINDS. HEATING TO START THE DAY WILL BE HINDERED AT FIRST AS MORNING FOG WILL BE SLOW TO BURN OFF. HEADING INTO THE COLDER MONTHS MORNING FOG WILL TAKE A BIT LATER TO CLEAR OUT. BUT SUNDAYS HIGHS WILL QUICKLY WARM INTO THE UPPER 60S AND AROUND 70 IN SOUTHERLY FLOW. SO A PLEASANT AND DRY FORECAST IS ON TAP BY SUNDAY. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 346 AM EDT SAT OCT 20 2012 AT THE START OF THE PERIOD...A TROUGH IS EXPECTED TO BE DEPARTING THE NORTHEASTERN US WITH RIDGING EXTENDING FROM MEXICO NORTH INTO THE WESTERN GULF AND MUCH OF THE SOUTHEASTERN US AND MS VALLEY TO LOWER OH VALLEY REGIONS. MEANWHILE A TROUGH IS EXPECTED TO BE DIGGING OFF THE NORTHWEST COAST. A COUPLE OF SHORTWAVES PER MODEL CONSENSUS ARE EXPECTED TO BE WORKING AROUND THE SOUTHEASTERN RIDGING...ONE MOVING THROUGH THE PLAINS AND APPROACHING THE MID MS VALLEY REGION AT THE START OF THE PERIOD WITH ANOTHER WORKING FROM THE DESERT SOUTHWEST TOWARD THE SOUTHERN PLAINS. THROUGH MONDAY NIGHT AND TUESDAY...HEIGHTS WILL RISE ALONG THE EASTERN SEABOARD AS THE TROUGH DEPARTS THE NORTHEASTERN US WITH RIDGING EXTENDING FROM MEXICO ACROSS THE GULF AND INTO THE SOUTHEASTERN STATES AROUND 12Z TUE PER MODEL CONSENSUS. THE FIRST OF THE SHORTWAVES MENTIONED PREVIOUSLY IS PROGGED TO PASS WELL TO OUR NW AND THEN NORTH AS IT MOVES IT AROUND THE RIDGING FROM SUN NIGHT INTO MONDAY. FAIRLY CLOSE ON ITS HEELS WILL BE THE NEXT SHORTWAVE WORKING ACROSS THE PLAINS AND TOWARD THE MID MS VALLEY REGION AND THEN NORTH OF THE AREA ON TUE. BOTH OF THESE SHOULD BRING JUST SOME HIGH AND MID CLOUDS FOR THE MOST PART...WITH ANY PRECIP CHANCES WELL WEST AND NORTH OF THE REGION. RIDING SHOULD THEN REASSERT ITSELF AT MIDWEEK OVER THE WESTERN GULF AND INTO THE SOUTHEASTERN US...WITH A RATHER BROAD TROUGH OVER THE WESTERN US AND EAST INTO THE PLAINS. A SHORTWAVE TROUGH ASSOCIATED WITH THIS BROAD THROUGH SHOULD GRADUALLY EJECT NORTHEAST TOWARD THE GREAT LAKES ON THU INTO THU NIGHT WITH RATHER ZONAL FLOW LEFT IN PLACE AT MIDWEEK. THERE ARE TIMING DIFFERENCES WITH THIS LAST SHORTWAVE AND THE EVOLUTION/STRENGTH OF A CLOSED LOW OVER THE GREAT LAKES/ONTARIO AREA AT THE END OF THE WEEK. HOWEVER...YET ANOTHER IN A SERIES OF SFC LOWS TRACKING ACROSS THE PLAINS AND INTO THE GREAT LAKES REGION IS ANTICIPATED WITH THE TRAILING RATHER SHEARED OUT BOUNDARY WORKING INTO THE REGION LATE IN THE PERIOD. THE ECMWF RUNS HAVE BEEN FASTER WITH THIS BOUNDARY OVER THE PAST FEW RUNS COMPARED TO THE GFS RUN. SFC RIDGING SHIFTING EAST INITIALLY IN THE PERIOD ALONG WITH SOME SUBSIDENCE ASSOCIATED WITH HEIGHT RISES SHOULD BE FAVORABLE FOR RIVER VALLEY FOG ON SUN NIGHT AND A RIDGE/VALLEY TEMP SPLIT. MANY OF THE VALLEY LOCATIONS...ESPECIALLY EAST SHOULD REACH THE UPPER 30S TO LOW 40S ON SUN NIGHT. TEMPERATURES WILL CONTINUE TO MODERATE ASSOCIATED WITH THE RISING HEIGHTS AND SOUTHERLY FLOW ON MON. THE MODEL CONSENSUS IS CURRENTLY BELOW THE MEX NUMBERS...BUT NUDGED TEMPS A DEGREE ABOVE THE MODEL CONSENSUS FOR MON. MIN T SHOULD MODERATE ON MON NIGHT AS WELL...THOUGH A RIDGE/VALLEY SPLIT IS STILL EXPECTED OVER THE SOUTHEASTERN COUNTIES WITH A SIMILAR MAGNITUDE AS SUN NIGHT. MIN T ON TUE NIGHT SHOULD BE A COLDER ON AVERAGE COMPARED TO MON NIGHT WITH THE RIDGE STARTING TO REASSERT ITSELF AND A BIT LESS CLOUD COVER ON AVERAGE WITH YET ANOTHER IN A SERIES OF RIDGE/VALLEY TEMP SPLITS. WED NIGHT SHOULD ALSO FAVOR A RIDGE/VALLEY TEMP SPLIT...BUT THU NIGHT SHOULD FEATURE A MINIMAL OR NO RIDGE/VALLEY TEMP SPLIT AS THE GRADIENT INCREASES AHEAD OF AN APPROACHING COLD FRONT. SOME TERRAIN ADJUSTMENTS WERE MADE TO THE GRID LOAD FOR MIN T FROM MON NIGHT THROUGH WED NIGHT TO REFLECT THE ABOVE MENTIONED RIDGE/VALLEY TEMP SPLITS. MAX TEMPS WILL MODERATE FURTHER INTO MIDWEEK AND REMAIN ABOVE NORMAL THROUGH THE END OF THE PERIOD. MAX TEMPS SHOULD NEAR 15 DEGREES ABOVE NORMAL ON WED AS 850 MB TEMPS REACH ABOUT THE 12 TO 15C RANGE. WED IS EXPECTED TO BE THE WARMEST DAY. DURING THE PAST COUPLE OF WARMER DAYS THE MEX HAS BEEN TOO WARM WITH MAX T AND THE GRID LOAD TEMPS IN THE UPPER 70S WERE ACCEPTED. THE ONLY POPS IN THE PERIOD WILL COME AT THE END OF THE PERIOD. IF THE FASTER ECMWF IS RIGHT OR MODELS TREND TOWARD IT...THEN POPS MAY NEED TO BE INCREASED ON THU NIGHT. HOWEVER...THE MODEL CONSENSUS GRID LOAD FAVORED POPS MAINLY ON FRI...AND THIS SEEMED TO BE A REASONABLE COMPROMISE GIVEN THE MODEL DIFFERENCES NOTED ABOVE. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 135 PM EDT SAT OCT 20 2012 CIGS REMAIN IN THE LOW END VFR TERRITORY THROUGH 00Z BEFORE GRADUALLY LIFTING OUT OVERNIGHT AS HIGH PRESSURE BEGINS TO MOVE IN FROM THE SW...BRINGING CALM WINDS ALONG WITH A POTENTIAL FOR IFR FOG OR WORSE TOWARDS DAYBREAK AROUND THE VALLEYS. ANY FOG THAT DEVELOPS WILL BEGIN TO MIX OUT BY 13Z WITH VFR PREVAILING UNDER CLEAR SKIES AND CONTINUED LIGHT WINDS THROUGH THE REMAINDER OF THE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SHALLENBERGER/MB SHORT TERM...SHALLENBERGER LONG TERM....JP AVIATION...MB
AREA FORECAST DISCUSSION
NWS GRAY ME
607 PM EDT SAT OCT 20 2012 .SYNOPSIS... A COLD FRONT WILL MOVE OFF THE COAST THIS EVENING. HIGH PRESSURE WILL BUILD TO OUR SOUTH LATE TONIGHT AND SUNDAY. AN UPPER LOW WILL GRADUALLY EXIT THE REGION ON MONDAY. A FRONT DRAPED ACROSS SOUTHERN NEW ENGLAND COULD BRUSH THE AREA WITH A FEW SHOWERS MIDWEEK. ANOTHER SYSTEM MAY IMPINGE ON THE REGION LATE NEXT WEEKEND. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 600 PM UPDATE... ALTHOUGH THE FRONT IS PUSHING THROUGH THE AREA IT IS TAKING ITS TIME MIXING OUT THE FOG...SO ADDED AN AREA OF PATCHY FOG BASED ON CURRENT OBSERVATIONS AND LIFTED IT OUT BASED ON THE HRRR FORECAST MIXING OUT THE FOG AND STRATUS AT ABOUT 02Z. TWEAKED SKY COVER AND ALSO TEMPERATURES BASED ON THE CURRENT OBSERVATIONS AND TRENDS. 350 PM UPDATE... STARTING TO SEE SOME CONVECTION IN THE NORTHERN ZONES AND WESTERN NEW HAMPSHIRE...SO ADDED SLIGHT CHANCE OF A THUNDERSTORM UNTIL 6 PM. THE CONVECTION SHOULD DISSIPATE SHORTLY AFTER SUNSET. PREVIOUS DISCUSSION... A FRONT WILL MOVE OFFSHORE BY THIS EVENING AND IN ITS WAKE A DRIER AIRMASS WILL ADVECT ACROSS THE AREA FROM SW TO NE. THE FOG OVER COASTAL AND ERN AREAS WILL GRADUALLY BE SWEPT EAST BY THIS EVENING AS THE WLY WINDS KICK IN BHND THE FROPA. A FEW SHWRS ARE PSBL ACRS NRN AREAS TNGT OTRW DRY CONDS AND COOLER TEMPS WILL PREVAIL. THERE SHOULD BE ENOUGH OF A WEST WIND AND MIXING TO PREVENT ANY FOG FROM DEVELOPING. USED A BLEND OF THE MAV/MET GUID FOR TEMPS. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... AN UPPER TROF CENTERED OVER QUEBEC MOVING NEWD WILL CONTINUE A CYCLONIC WSWLY FLOW ALOFT WITH A MORE WEST FLOW IN THE LOWER LEVELS. A FEW INSTBLTY SHWRS OVER THE MTNS ARE PSBL OTRW DRY DOWNSLOPING WINDS WILL PROVIDE PARTLY TO MOSTLY SUNNY CONDS WITH HIGH TEMPS MOSTLY IN THE 60S. MORE OF THE SAME IS EXPECTED SUN NIGHT ONLY DROPPING INTO THE 40S SINCE A LIGHT WLY BREEEZE SHOULD PERSIST ALLOWING ENOUGH MIXING AND NOT ALLOWING TEMPS TO FALL MUCH FURTHER. USED A BLEND OF THE MAV/MET GUID. && .LONG TERM /MONDAY THROUGH SATURDAY/... SOME UNCERTAINTY IN THE MODELS AS FAR AS TIMING OF LIGHT PRECIPITATION CHANCES FOR MIDWEEK. NW FLOW PATTERN IN PLACE...WITH SFC HIGH PRESSURE NOSING FROM THE NORTH. THIS SHOULD RESULT IN A DECENT N-S TEMPERATURE GRADIENT ACROSS THE NORTHEAST AND SOUTHERN CANADA. HOWEVER...MODELS DIFFER ON AMPLITUDE OF FLOW AND TIMING OF ANY SHORT WAVE TROUGH ENERGY. THE 12Z ECMWF IS PRETTY DRY ALL WEEK. HOWEVER...GFS ENS...OP GFS AND GGEM ALL HINTING AT ONE OR TWO PERIODS OF SHOWERS RIDING DOWN THE BAROCLINIC ZONE BETWEEN LATE TUESDAY AND THURSDAY. NOT SOLD ON ANY HIGH POPS AT THIS TIME...BUT DID CENTER SOME LOW CHANCES OR SLIGHT CHANCES TUESDAY NIGHT INTO THURSDAY. THEREAFTER...IT LOOKS LIKE THE CHANCES FOR PRECIPITATION INCREASES LATE NEXT WEEKEND AS A SYSTEM LOOKS TO EJECT OUT OF THE PLAINS/LAKES. HOWEVER...IT/S A LONG WAY OUT. && .AVIATION /22Z SATURDAY THROUGH THURSDAY/... SHORT TERM /THROUGH SUNDAY/...MVFR TO IFR CONDS OVR COASTAL AND ERN AREAS THRU LATE EVENING BUT IMPROVING TO VFR BY LATER TONIGHT. ELSEWHR VFR CONDS THRU SUN NIGHT. LONG TERM...MAINLY VFR DURING THE UPCOMING WEEK. HOWEVER...THERE COULD BE A FEW BRIEF PERIODS OF MVFR CIGS AND/OR VSBYS TUESDAY NIGHT INTO WEDNESDAY NIGHT IN LIGHT SHOWERS. AS FAR AS WINDS GO...SFC GUSTS FROM THE W/NW MONDAY TO 25 KT. && .MARINE... SHORT TERM...WILL CONTINUE THE SCA BUT ONLY DUE TO SEAS AS WINDS WILL BE BELOW SCA CRITERIA BUT THE SEAS WILL BE SLOW TO SUBSIDE. THE SEAS WILL SUBSIDE TO BELOW 5 FT BY MRNG WHILE THE OUTER WATERS MAY NOT DROP BELOW 5 FT UNTIL SUNDAY EVENING. LONG TERM...SCA CONDITIONS MONDAY AND MONDAY NIGHT WITH W GUSTS AROUND 25 KT. THEREAFTER...CONDITIONS SUBSIDE AS HIGH PRESSURE MOVES IN. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT SUNDAY FOR ANZ151-153. SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 PM EDT SUNDAY FOR ANZ150-152-154. && $$ NEAR TERM...KISTNER
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
319 PM CDT SAT OCT 20 2012 .SHORT TERM...TONIGHT THROUGH TUESDAY 319 PM CDT SAT OCT 20 2012 THE MAIN CHALLENGES THROUGH EARLY NEXT WEEK REST WITH WHETHER THE STRATUS/FOG WILL REDEVELOP TONIGHT...THE RAIN/THUNDER CHANCES SUNDAY NIGHT THROUGH TUESDAY...AND TEMPERATURES AS A COLD FRONT STALLS ACROSS THE REGION. FIRST...TWO BANDS OF STRATUS AND FOG LINGERED THROUGH THIS MORNING WITH ONE BAND ASSOCIATED WITH AN INVERTED SURFACE TROUGH IN NORTHEAST WISCONSIN AND A SECOND BAND ASSOCIATED WITH WEAK 925/850MB CONVERGENCE ABOVE A SURFACE RIDGE ALONG AND WEST OF THE MISSISSIPPI RIVER. DIURNAL HEATING AND MIXING HAS ERODED THE EDGES OF THESE BANDS AND CONVERTED THE STRATUS INTO A CUMULUS FIELD...BUT THE QUESTION REMAINS WITH WHETHER THIS STRATUS REDEVELOPS OVERNIGHT AGAIN. THE RAP HAS DONE THE BEST WITH SHOWING THIS LOW LEVEL MOISTURE BEING TRAPPED UNDER AN INVERSION AROUND 900MB THAT STRENGTHENS TONIGHT AS LOW LEVEL WARM AIR ADVECTION KICKS IN. THE WESTERN EDGE OF THE STRATUS/FOG FIELD ACROSS MINNESOTA AND IOWA APPEARS TO ALSO BE TIED TO THE 925/850MB TEMPERATURE GRADIENT WHERE LOW LEVEL WINDS COME AROUND TO THE WEST-SOUTHWEST. THE 20.12Z NAM/GFS/RAP SLOWLY BRINGS THIS LOW LEVEL TEMPERATURE GRADIENT THROUGH THE REGION OVERNIGHT...BUT WITH THE SURFACE RIDGE STILL OVERHEAD AND A SHALLOW INVERSION IN PLACE IT APPEARS THAT SOME STRATUS OR FOG WILL AGAIN DEVELOP TONIGHT. CONFIDENCE IS NOT HIGH ENOUGH AT THIS POINT TO PUT DENSE FOG IN THE FORECAST...BUT IT IS A POSSIBILITY...PARTICULARLY ACROSS WESTERN WISCONSIN. WINDS FROM THE SURFACE ON UP WILL BE OUT OF THE SOUTH TOMORROW AS A WARMER AIR MASS MOVES INTO THE REGION. THE NEXT CHANCES FOR PRECIPITATION WILL COME IN TOMORROW NIGHT AS A CUT OFF MID LEVEL LOW CURRENTLY OFF THE BAJA OF CALIFORNIA GETS CAUGHT IN THE SOUTHWESTERLY FLOW ALOFT AND QUICKLY TRACKS ACROSS THE SOUTHERN PLAINS AND INTO THE MID TO UPPER MISSISSIPPI RIVER VALLEY REGION BY EARLY MONDAY. THIS FEATURE WILL HELP TO BRING A SURFACE LOW PRESSURE SYSTEM UP ALONG A STALLING OUT COLD FRONT TOMORROW NIGHT INTO MONDAY WHICH WILL INCREASE THE LOW LEVEL MOISTURE TRANSPORT OUT OF THE GULF OVER THIS PERIOD. BASED ON 20.12Z NAM/GFS BUFKIT SOUNDINGS...THERE DOES APPEAR TO BE SOME ELEVATED INSTABILITY THAT DEVELOPS EARLY MONDAY WITH 0-3KM MUCAPE CLIMBING UP TO AROUND 1000 J/KG. A VEERING WIND PROFILE WITH HEIGHT MAY PROVIDE ENOUGH WIND SHEAR FOR A FEW ISOLATED HAILERS TO FORM AS WELL. THIS COLD FRONT WILL THEN BECOME STATIONARY ON MONDAY AS ANOTHER SURFACE LOW DEVELOPS ALONG THE SOUTHERN PERIPHERY OF IT IN THE CENTRAL PLAINS. THE 20.12Z GFS/ECMWF ARE MORE ROBUST WITH QPF THROUGH THE DAY ON MONDAY COMPARED TO THE NAM WITH THE HIGHER PROBABILITIES OF RAIN ACROSS SOUTHERN WISCONSIN. WITH SOUTHWESTERLY FLOW ALOFT...ANOTHER LOW WILL TRACK ACROSS MONTANA AND HELP TO BRING THE WARM AIR MASS IN PLACE THROUGH THE PLAINS FURTHER NORTH ACROSS THE REGION. WITH SOME INSTABILITY LINGERING ALONG THE FRONT...CAN NOT RULE OUT SOME SHOWERS/THUNDERSTORMS MONDAY NIGHT INTO TUESDAY AS THE FRONT KICKS BACK TO THE NORTH AS A WARM FRONT. DEW POINTS SOUTH OF THE FRONT LOOK TO BE FAIRLY HUMID FOR THIS TIME OF YEAR WITH THEM CLIMBING INTO THE 50S TOMORROW NIGHT AND THEN INTO THE 60S BY TUESDAY. CONFIDENCE IS NOT HIGH WITH THE EXACT TIMING AND INTENSITY OF THE SHOWERS/STORMS GOING FROM MONDAY NIGHT INTO TUESDAY...BUT THERE SHOULD BE BREAKS IN THE ROUNDS OF SHOWERS/STORMS. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY 319 PM CDT SAT OCT 20 2012 WARM AIR WILL REMAIN ACROSS THE REGION WITH SOUTHWESTERLY LOW TO UPPER LEVEL FLOW IN PLACE THROUGH MUCH OF THE CENTRAL US INTO THE GREAT LAKES. AS THE SURFACE WARM FRONT LIFTS NORTH TUESDAY NIGHT INTO WEDNESDAY...THE NEXT LOW PRESSURE SYSTEM WILL DEVELOP IN THE CENTRAL PLAINS AND TRACK THROUGH THE UPPER GREAT LAKES REGION BY WEDNESDAY NIGHT. THIS WILL HELP TO BRING A COLD FRONT THROUGH WEDNESDAY INTO WEDNESDAY NIGHT WITH SHOWERS/THUNDERSTORMS DEVELOPING ALONG IT. THE 20.12Z ECMWF/GEM IS THE PREFERRED SOLUTION WITH A QUICKER TREND OF BRINGING THE COLD FRONT THROUGH COMPARED TO THE 20.12Z GFS WHICH WAITS UNTIL THURSDAY TO BRING IT THROUGH. HAVE KEPT SOME CHANCES IN THERE FOR THURSDAY TO ACCOUNT FOR THE GFS SOLUTION...BUT IF IT STARTS TO TREND TOWARD THE OTHER GUIDANCE IT MAY END UP DRY THAT DAY. THE NEXT FEATURE TO WATCH IS WITH NEXT FRIDAY AND WHICH WAY THE MODELS TREND WITH ANOTHER SYSTEM THAT LIFTS OUT OF THE SOUTHERN PLAINS. MUCH OF THE PREVIOUS GUIDANCE HAS KEPT THIS SYSTEM WELL TO THE SOUTHEAST AND NOT AFFECTING THE REGION...THOUGH THE 20.12Z ECMWF CAME IN WITH A SOLUTION FURTHER TO THE NORTHWEST. THIS WOULD PRODUCE A LENGTHY BAND OF PRECIPITATION FROM THE SOUTHERN PLAINS INTO THE WESTERN GREAT LAKES WITH THE WESTERN EDGE OF IT COVERING THE FORECAST AREA. SURFACE WET BULB TEMPERATURES AND THE TEMPERATURE PROFILE ABOVE THE GROUND LOOK WARM ENOUGH FOR THE P-TYPE TO BE ALL LIQUID...BUT IT WILL BE CLOSE TO FREEZING AND WILL HAVE TO BE MONITORED OVER THE NEXT WEEK. && .AVIATION...THROUGH 18Z SUNDAY 1236 PM CDT SAT OCT 20 2012 STRATUS/FOG WILL CONTINUE TO BE THE MAIN CONCERN THROUGH THE TAF PERIOD. SKIES HAVE FINALLY CLEARED AT KLSE WITH MOSTLY IFR STRATUS HOLDING FIRM ACROSS THE HIGHER TERRAIN OF SOUTHEAST MN/NORTHEAST IA...INCLUDING KRST TAF SITE. THIS LOW LEVEL MOISTURE IS TRAPPED UNDER A RIDGE OF HIGH PRESSURE EXTENDING PRETTY MUCH N/S ALONG THE MISSISSIPPI RIVER VALLEY. RIDGE AXIS TO SHIFT SLOWLY EASTWARD TONIGHT WITH WINDS OUT THE SOUTH AROUND 5KT OR SO AT THE KLSE/KRST TAF SITES. WITH COOLING OF THE RELATIVELY MOIST LOWER BOUNDARY LAYER...EXPECTING IFR/LIFR STRATUS FILL IN AGAIN AFTER SUNSET. MODEL SOUNDINGS HAVE WINDS JUST OFF THE SURFACE AT 600-900FT AGL EXPECTED IN THE 15-20KT RANGE FROM THE SOUTH- SOUTHWEST OVERNIGHT. THIS SHOULD PREVENT DENSE FOG FORMATION AT THE SURFACE BUT MAINTAINING IFR/LIFR STRATUS. EXPECTING LOW CLOUDS TO SCATTER FINALLY AROUND 14Z SUNDAY AS BETTER BOUNDARY LAYER MIXING OCCURS IN SOUTHERLY FLOW. THROUGH THE REST OF SUNDAY...AFTER THE STRATUS SCATTERS...PLAN ON SCATTERED MID/HIGH CLOUDS WITH BASES AOA 12KFT. && .ARX WATCHES/WARNINGS/ADVISORIES... 319 PM CDT SAT OCT 20 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM...HALBACH AVIATION...DAS