Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 09/06/14


AREA FORECAST DISCUSSION
NWS PHOENIX AZ
315 PM MST THU SEP 4 2014 ...UPDATED AVIATION AND FIRE WEATHER... .SYNOPSIS... INCREASING SOUTHERLY FLOW ALOFT WILL CONTINUE TO GRADUALLY INCREASE MOISTURE LEVELS OVER THE DESERT SOUTHWEST THROUGH FRIDAY...WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS OVER THE REGION. A FURTHER INCREASE IN MOISTURE IS EXPECTED THIS WEEKEND AS MOISTURE FROM THE REMAINS OF HURRICANE NORBERT SURGES INLAND INTO THE REGION...WITH HEAVY RAIN AND LOCALIZED FLOODING POSSIBLE. A SLOW DRYING TREND IS THEN EXPECTED TO BEGIN NEXT WEEK AS HIGH PRESSURE SLOWLY REBUILDS OVER THE REGION. && .DISCUSSION... TONIGHT AND FRIDAY... MODELS CONTINUE TO BE CONSISTENT ON THE FORECAST THROUGH FRIDAY...WITH A SLOW INCREASE IN THE PWAT VALUES OVER AZ TONIGHT INTO EARLY FRIDAY...MOST LIKELY INTO THE 1.50-1.60 INCH RANGE. THIS MODEST MOISTURE...COMBINED WITH A WEAK SHORTWAVE THAT IS NOW SEEN IN THE LATEST WV SATELLITE IMAGERY MOVING INTO EXTREME SOUTHERN AZ...IS NOW TRIGGERING ISOLATED TO SCATTERED THUNDERSTORMS OVER PIMA COUNTY. THE LATEST HRRR HI-RES MODEL RUN IS NOW SHOWING MOST OF THESE STORMS REMAINING TO THE SOUTH OF OUR CWA...BUT WITH A FEW OF THE STORMS MOVING INTO OR DEVELOPING OVER SOUTH-CENTRAL AZ. THE MAIN THREAT FROM THESE STORMS WILL BE GUSTY WINDS AND BLOWING DUST...WITH ONLY A SLIGHT CHANCE FOR MEASURABLE RAIN AT ANY ONE SPOT. FRIDAY STILL LOOKS LIKE A BIT OF A DOWN DAY...WITH THE LATEST GFS PRETTY MUCH MATCHING EARLIER RUNS...WITH WEAK HIGH PRESSURE RIDGING REBUILDING INTO THE REGION FROM THE WEST AND PWATS FALLING A BIT...INTO THE 1.40-1.50 INCH RANGE...WHICH SHOULD KEEP TS ACTIVITY LIMITED TO SOUTH-CENTRAL AZ...MOSTLY OVER THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX. SATURDAY THROUGH MONDAY... THIS PERIOD LOOKS MORE-AND-MORE LIKELY THAT IT WILL BE A QUITE ACTIVE...AS MOISTURE FROM HURRICANE NORBERT BEGINS TO IMPACT THE REGION. THE LATEST (21Z) NHC FORECAST CONTINUES TO TRACK THIS STORM TO THE WEST OF THE BAJA CALIFORNIA PENINSULA OVER THE NEXT 3-5 DAYS...WITH AN UPPER TROF THAT WILL BE MOVING SOUTHWARD ALONG THE NORTHERN AND CENTRAL CA COAST SHEARING MID AND HIGH-LEVEL MOISTURE NORTHWESTWARD INTO OUR REGION FROM THIS STORM. LATEST MODEL RUNS ALSO ARE SHOWING A BROAD AREA OF LOW-LEVEL SOUTHEASTERLY FLOW PUSHING VERY MOIST AIR NORTHWARD ACROSS THE GULF OF CALIFORNIA INTO AZ AND SE CA...WITH SFC DEWPOINTS EXCEEDING 70F AT ANY LOWER DESERT LOCATIONS BY SUNDAY MORNING AND PWATS RISING WELL ABOVE 2 INCHES...WHICH IS AT NEAR-RECORD VALUES FOR EARLY SEPT. GIVEN THESE VERY HIGH AVAILABLE MOISTURE LEVELS...WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY NOW APPEARS TO BE VERY LIKELY FROM LATE SAT INTO MONDAY...WITH HEAVY RAIN AND LOCALIZED FLOODING BEING THE MAIN THREATS FROM STORM-TOTAL RAINFALL AMOUNTS OF 1-2 INCHES...OR EVEN MORE AT MANY LOWER DESERT LOCATIONS. THE RAIN AND CLOUDS ARE ALSO EXPECTED TO COOL TEMPS SUBSTANTIALLY DURING THIS PERIOD...WITH HIGHS REMAINING IN THE 90S...AND EVEN A FEW 80S ACROSS THE LOWER DESERTS EACH DAY. TUESDAY THROUGH THURSDAY... A SLOW DRYING TREND IS EXPECTED THROUGH THIS PERIOD AS INCREASING WESTERLY FLOW AND BUILDING HIGH PRESSURE OVER THE REGION HELPS TO SWEEP ANY REMAINING MOISTURE FROM NORBERT WELL OFF TO OUR EAST...WITH THE THREAT OF THUNDERSTORM ACTIVITY LIKELY ENDING OVER OUR CWA BY WEDNESDAY OR THURSDAY...WITH DAYTIME HIGHS REBOUNDING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES. && .AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL... OVERALL FORECAST CONFIDENCE (ESPECIALLY TIMING OF WIND SHIFTS) IS LOWER THAN NORMAL THROUGH TONIGHT. ISOLATED THUNDERSTORMS SHOULD REMAIN BOTH WELL SOUTH AND NORTH OF TERMINALS THROUGH TONIGHT...HOWEVER BRIEF PERIODS OF GUSTY OUTFLOW WINDS MAY AFFECT THE AIRFIELDS EARLY THIS EVENING. HAVE INDICATED A WIND SHIFT EARLIER THAN USUAL...BUT BELOW ANY OPERATIONAL IMPACT. THERE IS AN OUTSIDE CHANCE OF STRONGER WIND GUSTS AND BLOWING DUST...HOWEVER UNCERTAINTY IS TOO HIGH TO INCLUDE IN THE TAF PACKAGE. ONLY PERIODIC MIDLEVEL CLOUDS AOA 9K FT AND LIGHT EAST WINDS ARE LIKELY AFTER MIDNIGHT. SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH... MOSTLY CLEAR SKIES SHOULD PREVAIL THROUGH FRIDAY MORNING...THOUGH SOME INCREASE IN A SCT LOWER DECK...AS WELL AS HIGH DECK MAY BE POSSIBLE. WIND DIRECTION FORECASTS ARE OF LOWER CONFIDENCE AS OUTFLOW WINDS AND SOUTHERLY SURGES OF MOISTURE MAY BRING STRONGER GUSTS EVEN DURING OVERNIGHT HOURS. IN GENERAL...A SOUTHERLY OR SOUTHEASTERLY COMPONENT WILL BE FAVORED. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SUNDAY THROUGH THURSDAY... MOISTURE WILL ALREADY HAVE ENVELOPED SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA BY SUNDAY...WITH THE POTENTIAL FOR HEAVY RAINFALL OVER MUCH OF THE REGION. STORM CHANCES WILL CONTINUE THROUGH TUESDAY BEFORE TRENDING DOWNWARD THROUGH MIDWEEK. HUMIDITIES WILL REMAIN VERY ELEVATED DURING THE ENTIRE PERIOD...ONLY FALLING INTO A 30-40 PERCENT RANGE IN THE AFTERNOON WITH MOSTLY COOLER THAN AVERAGE TEMPERATURES. WINDS MAY BE GUSTY IN AND AROUND THUNDERSTORMS...AND STAY VARIABLE FOR PROLONGED PERIODS OTHERWISE. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...PERCHA AVIATION...MO FIRE WEATHER...MO
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
240 PM MST THU SEP 4 2014 && .SYNOPSIS... INCREASING SOUTHERLY FLOW ALOFT WILL CONTINUE TO GRADUALLY INCREASE MOISTURE LEVELS OVER THE DESERT SOUTHWEST THROUGH FRIDAY...WITH ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS LIKELY OVER THE REGION. A FURTHER INCREASE IN MOISTURE IS EXPECTED THIS WEEKEND AS MOISTURE FROM THE REMAINS OF HURRICANE NORBERT SURGES INLAND INTO THE REGION...WITH HEAVY RAIN AND LOCALIZED FLOODING POSSIBLE. A SLOW DRYING TREND IS THEN EXPECTED TO BEGIN NEXT WEEK AS HIGH PRESSURE SLOWLY REBUILDS OVER THE REGION. && .DISCUSSION... TONIGHT AND FRIDAY... MODELS CONTINUE TO BE CONSISTENT ON THE FORECAST THROUGH FRIDAY...WITH A SLOW INCREASE IN THE PWAT VALUES OVER AZ TONIGHT INTO EARLY FRIDAY...MOST LIKELY INTO THE 1.50-1.60 INCH RANGE. THIS MODEST MOISTURE...COMBINED WITH A WEAK SHORTWAVE THAT IS NOW SEEN IN THE LATEST WV SATELLITE IMAGERY MOVING INTO EXTREME SOUTHERN AZ...IS NOW TRIGGERING ISOLATED TO SCATTERED THUNDERSTORMS OVER PIMA COUNTY. THE LATEST HRRR HI-RES MODEL RUN IS NOW SHOWING MOST OF THESE STORMS REMAINING TO THE SOUTH OF OUR CWA...BUT WITH A FEW OF THE STORMS MOVING INTO OR DEVELOPING OVER SOUTH-CENTRAL AZ. THE MAIN THREAT FROM THESE STORMS WILL BE GUSTY WINDS AND BLOWING DUST...WITH ONLY A SLIGHT CHANCE FOR MEASURABLE RAIN AT ANY ONE SPOT. FRIDAY STILL LOOKS LIKE A BIT OF A DOWN DAY...WITH THE LATEST GFS PRETTY MUCH MATCHING EARLIER RUNS...WITH WEAK HIGH PRESSURE RIDGING REBUILDING INTO THE REGION FROM THE WEST AND PWATS FALLING A BIT...INTO THE 1.40-1.50 INCH RANGE...WHICH SHOULD KEEP TS ACTIVITY LIMITED TO SOUTH-CENTRAL AZ...MOSTLY OVER THE HIGHER TERRAIN NORTH AND EAST OF PHOENIX. SATURDAY THROUGH MONDAY... THIS PERIOD LOOKS MORE-AND-MORE LIKELY THAT IT WILL BE A QUITE ACTIVE...AS MOISTURE FROM HURRICANE NORBERT BEGINS TO IMPACT THE REGION. THE LATEST (21Z) NHC FORECAST CONTINUES TO TRACK THIS STORM TO THE WEST OF THE BAJA CALIFORNIA PENINSULA OVER THE NEXT 3-5 DAYS...WITH AN UPPER TROF THAT WILL BE MOVING SOUTHWARD ALONG THE NORTHERN AND CENTRAL CA COAST SHEARING MID AND HIGH-LEVEL MOISTURE NORTHWESTWARD INTO OUR REGION FROM THIS STORM. LATEST MODEL RUNS ALSO ARE SHOWING A BROAD AREA OF LOW-LEVEL SOUTHEASTERLY FLOW PUSHING VERY MOIST AIR NORTHWARD ACROSS THE GULF OF CALIFORNIA INTO AZ AND SE CA...WITH SFC DEWPOINTS EXCEEDING 70F AT ANY LOWER DESERT LOCATIONS BY SUNDAY MORNING AND PWATS RISING WELL ABOVE 2 INCHES...WHICH IS AT NEAR-RECORD VALUES FOR EARLY SEPT. GIVEN THESE VERY HIGH AVAILABLE MOISTURE LEVELS...WIDESPREAD SHOWER/THUNDERSTORM ACTIVITY NOW APPEARS TO BE VERY LIKELY FROM LATE SAT INTO MONDAY...WITH HEAVY RAIN AND LOCALIZED FLOODING BEING THE MAIN THREATS FROM STORM-TOTAL RAINFALL AMOUNTS OF 1-2 INCHES...OR EVEN MORE AT MANY LOWER DESERT LOCATIONS. THE RAIN AND CLOUDS ARE ALSO EXPECTED TO COOL TEMPS SUBSTANTIALLY DURING THIS PERIOD...WITH HIGHS REMAINING IN THE 90S...AND EVEN A FEW 80S ACROSS THE LOWER DESERTS EACH DAY. TUESDAY THROUGH THURSDAY... A SLOW DRYING TREND IS EXPECTED THROUGH THIS PERIOD AS INCREASING WESTERLY FLOW AND BUILDING HIGH PRESSURE OVER THE REGION HELPS TO SWEEP ANY REMAINING MOISTURE FROM NORBERT WELL OFF TO OUR EAST...WITH THE THREAT OF THUNDERSTORM ACTIVITY LIKELY ENDING OVER OUR CWA BY WEDNESDAY OR THURSDAY...WITH DAYTIME HIGHS REBOUNDING TO NEAR...OR SLIGHTLY ABOVE NORMAL VALUES. && .AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL... ISOLATED SHOWERS/THUNDERSTORMS EXPECTED ACROSS SOUTH-CENTRAL ARIZONA THIS MORNING...MAINLY ACROSS HIGHER TERRAIN AREAS TO THE NORTH AND EAST OF PHOENIX...WITH SCT-BKN CLOUD DECKS AOA 10KFT. WINDS WILL CONTINUE TO FAVOR EAST-SOUTHEAST GENERALLY 10KT OR LESS...AND MAY SWITCH TO SOUTHWEST BRIEFLY FOR A COUPLE HOURS IF THERE IS SUFFICIENT CLEARING OF MID-LEVEL CLOUD DECKS LATE THIS AFTERNOON. ISOLATED SHOWER/THUNDERSTORMS ACTIVITY ENCROACHES ONCE AGAIN NEAR TERMINALS THIS EVENING...BUT UNCERTAINTY IN TIMING/COVERAGE WARRANTS LEAVING ANY MENTION OF WEATHER OUT OF THE TAFS AT THIS TIME. SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH... LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE TODAY...WITH MOSTLY CLEAR SKIES AND JUST A FEW-SCT MID LEVEL CUMULUS. WINDS SHOULD CONTINUE TO FAVOR SOUTH-SOUTHEAST GENERALLY 10KT OR LESS...EXCEPT ALONG THE LOWER COLORADO RIVER VALLEY/NEAR KBLH WHERE GUSTS UP TO 25KT WILL ACCOMPANY ADDITIONAL MOISTURE SURGE AFTER 06Z FRIDAY. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SATURDAY THROUGH WEDNESDAY... MONSOON MOISTURE WILL CONTINUE TO INCREASE AND SPREAD NORTH AND WEST REACHING THE LOWER DESERTS OF SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA BY SATURDAY. STORM CHANCES WILL CONTINUE THROUGH TUESDAY BEFORE TRENDING DOWNWARD LATE IN THE PERIOD. HUMIDITIES WILL REMAIN ELEVATED DURING THE PERIOD...WHILE TEMPERATURES TREND DOWNWARD. WINDS WILL FOLLOW FAMILIAR SUMMERTIME SLOPE-VALLEY PATTERNS BUT WITH SIGNIFICANT DISRUPTIONS DUE TO THUNDERSTORM ACTIVITY. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...PERCHA AVIATION...MEYERS FIRE WEATHER...AJ/MEYERS
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
845 AM MST THU SEP 4 2014 && .SYNOPSIS... MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA. SHOWERS AND THUNDERSTORMS WILL REMAIN MORE ISOLATED OVER THE HIGHER TERRAIN THROUGH FRIDAY...BUT SHOULD BECOME MORE PERIODIC AND WIDESPREAD BY THE END OF THE WEEKEND AND EARLY NEXT WEEK. HEAVY RAINFALL AND LOCALIZED FLOODING WILL BE THE PRIMARY THREATS WITH THESE STORMS LATE IN THE WEEKEND...WITH CLEARING ONLY SLOWLY OCCURRING NEXT WEEK. && .DISCUSSION... LATEST SATELLITE AND RADAR IMAGERY IS NOW SHOWING A CLEARING TREND ACROSS SOUTH-CENTRAL ARIZONA AS THE WEAK TROUGH THAT TRIGGERED THUNDERSTORM ACTIVITY ACROSS NORTHWEST MARICOPA COUNTY MOVES NORTHWARD INTO NORTHERN YAVAPAI AND COCONINO COUNTIES...WITH WEAK SUBSIDENCE BEHIND THIS FEATURE CLEARING THE SKIES ACROSS OUR CWA. BASED ON THE LATEST HRRR AND RUC13 MODEL OUTPUT...HAVE DECIDED TO REDUCE POPS IN THE 18Z-00Z TIME FRAME ACROSS WESTERN MARICOPA COUNTY...BUT LEFT ELEVATED POPS ALONE ACROSS EXTREME EASTERN MARICOPA COUNTY AND POINTS EAST...SINCE THESE MODELS ARE SILL SHOWING SOME SPRINKLES/LIGHT SHOWERS DEVELOPING ACROSS THAT REGION. OTHERWISE...WILL BE LEAVING INHERITED GRIDS ALONE FOR NOW. && .PREVIOUS DISCUSSION... LATEST RAP STREAMLINE ANALYSIS SHOWS A WEAK TROUGH ACROSS SOUTHERN CA WITH DEEPER MOISTURE LIFTING NORTHWARD ACROSS AZ IN A SOUTHWESTERLY FLOW. ISOLATED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED EARLY THIS MORNING...MAINLY ACROSS NORTHWESTERN PORTIONS OF MARICOPA COUNTY...PRODUCING BRIEF HEAVY RAIN. GIVEN THE LACK OF ELEVATED CAPE...THE ACTIVITY IS PRESUMABLY BEING AIDED BY VORTICITY-FORCED ASCENT AHEAD OF THE AFOREMENTIONED TROUGH AND A GRAVITY WAVE PROPAGATING NORTHWESTWARD FROM EARLIER CONVECTION ACROSS SOUTHERN AZ. LATEST HRRR HAS ASSIMILATED THIS ACTIVITY AND SUGGESTS IT WILL TREK INTO CENTRAL AND NORTHERN AZ AS IT IS ABSORBED INTO THE DEEPER SOUTHWESTERLY FLOW LATER THIS MORNING. THEREAFTER...GLOBAL AND CONVECTIVE-ALLOWING MODELS INDICATE A WIDE RANGE OF POSSIBILITIES. CONCEPTUALLY...STRONGEST ASCENT WILL SPREAD NORTH AND EASTWARD INTO THE HIGHER ELEVATIONS OF EASTERN AZ. HOWEVER...STEADILY INCREASING PWATS AS FAR WEST AS SOUTHWESTERN MARICOPA COUNTY WARRANT A SLIGHT CHANCE OF PRECIPITATION THROUGHOUT THE DAY. GIVEN THE INCREASING MOISTURE AND DECREASING THICKNESSES...TEMPERATURES WILL BE A FEW DEGREES COOLER THAN THOSE OBSERVED WEDNESDAY. HIGH PRESSURE WILL BRIEFLY REBUILD ACROSS THE FORECAST AREA FRIDAY...RESULTING IN A WEAKER WESTERLY FLOW. CONSEQUENTLY...INCREASE IN PWATS WILL TAKE A BRIEF HIATUS ACROSS THE LOWER DESERTS AND CONVECTION WILL BE MOST CONCENTRATED ACROSS SOUTHERN AND EASTERN AZ. MODELS REMAIN CONSISTENT THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK WITH THEIR DEPICTION OF DEEPER TROPICAL MOISTURE LIFTING NORTHWARD OUT OF MEXICO AND INTO THE DESERT SOUTHWEST. ALTHOUGH NEARBY HURRICANE NORBERT WILL LIKELY NOT HAVE A DIRECT IMPACT ON OUR WEATHER...ITS INFLUENCE WILL BE FAVORABLE FOR PRECIPITATION WITHIN THE REGION. OFFICIAL NHC FORECASTS INDICATE THAT THE WEAKENING TC WILL MORE OR LESS TRACK PARALLEL TO THE BAJA PENINSULA...SUGGESTING THAT MOISTURE TRANSPORT WILL BE MAXIMIZED ACROSS PORTIONS OF AZ. MODELS SUGGEST THAT PWATS WILL APPROACH 2 INCHES SUNDAY...INCREASING THE LIKELIHOOD OF HEAVY RAIN AND FLOODING. RECENT TRENDS IN THE ECWMF ALSO SUGGEST A SOMEWHAT SLOWER ONSET OF THE DEEPER MOISTURE...WITH THE BEST CHANCE FOR PRECIPITATION OCCURRING SUNDAY AND MONDAY. HOWEVER...THE GFS PAINTS A DIFFERENT PICTURE WITH THE DEVELOPMENT OF A DRY SLOT MONDAY BETWEEN THE REMNANTS OF NORBERT AND DEEPER MOISTURE TO THE EAST. BOTTOM LINE IS THAT CONSIDERABLE UNCERTAINTY REMAINS...THOUGH IT APPEARS MORE LIKELY THAT A WIDESPREAD 1 TO 2 INCHES OF RAIN CAN BE EXPECTED FROM MARICOPA COUNTY EASTWARD THROUGH TUESDAY. && .AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL... ISOLATED SHOWERS/THUNDERSTORMS EXPECTED ACROSS SOUTH-CENTRAL ARIZONA THIS MORNING...MAINLY ACROSS HIGHER TERRAIN AREAS TO THE NORTH AND EAST OF PHOENIX...WITH SCT-BKN CLOUD DECKS AOA 10KFT. WINDS WILL CONTINUE TO FAVOR EAST-SOUTHEAST GENERALLY 10KT OR LESS...AND MAY SWITCH TO SOUTHWEST BRIEFLY FOR A COUPLE HOURS IF THERE IS SUFFICIENT CLEARING OF MID-LEVEL CLOUD DECKS LATE THIS AFTERNOON. ISOLATED SHOWER/THUNDERSTORMS ACTIVITY ENCROACHES ONCE AGAIN NEAR TERMINALS THIS EVENING...BUT UNCERTAINTY IN TIMING/COVERAGE WARRANTS LEAVING ANY MENTION OF WEATHER OUT OF THE TAFS AT THIS TIME. SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH... LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE TODAY...WITH MOSTLY CLEAR SKIES AND JUST A FEW-SCT MID LEVEL CUMULUS. WINDS SHOULD CONTINUE TO FAVOR SOUTH-SOUTHEAST GENERALLY 10KT OR LESS...EXCEPT ALONG THE LOWER COLORADO RIVER VALLEY/NEAR KBLH WHERE GUSTS UP TO 25KT WILL ACCOMPANY ADDITIONAL MOISTURE SURGE AFTER 06Z FRIDAY. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SATURDAY THROUGH WEDNESDAY... MONSOON MOISTURE WILL CONTINUE TO INCREASE AND SPREAD NORTH AND WEST REACHING THE LOWER DESERTS OF SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA BY SATURDAY. STORM CHANCES WILL CONTINUE THROUGH TUESDAY BEFORE TRENDING DOWNWARD LATE IN THE PERIOD. HUMIDITIES WILL REMAIN ELEVATED DURING THE PERIOD...WHILE TEMPERATURES TREND DOWNWARD. WINDS WILL FOLLOW FAMILIAR SUMMERTIME SLOPE-VALLEY PATTERNS BUT WITH SIGNIFICANT DISRUPTIONS DUE TO THUNDERSTORM ACTIVITY. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...PERCHA/HIRSCH AVIATION...MEYERS FIRE WEATHER...AJ/MEYERS
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
513 AM MST THU SEP 4 2014 .UPDATE...UPDATED AVIATION DISCUSSION. && .SYNOPSIS... MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA. SHOWERS AND THUNDERSTORMS WILL REMAIN MORE ISOLATED OVER THE HIGHER TERRAIN THROUGH FRIDAY...BUT SHOULD BECOME MORE PERIODIC AND WIDESPREAD BY THE END OF THE WEEKEND AND EARLY NEXT WEEK. HEAVY RAINFALL AND LOCALIZED FLOODING WILL BE THE PRIMARY THREATS WITH THESE STORMS LATE IN THE WEEKEND...WITH CLEARING ONLY SLOWLY OCCURRING NEXT WEEK. && .DISCUSSION... LATEST RAP STREAMLINE ANALYSIS SHOWS A WEAK TROUGH ACROSS SOUTHERN CA WITH DEEPER MOISTURE LIFTING NORTHWARD ACROSS AZ IN A SOUTHWESTERLY FLOW. ISOLATED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED EARLY THIS MORNING...MAINLY ACROSS NORTHWESTERN PORTIONS OF MARICOPA COUNTY...PRODUCING BRIEF HEAVY RAIN. GIVEN THE LACK OF ELEVATED CAPE...THE ACTIVITY IS PRESUMABLY BEING AIDED BY VORTICITY-FORCED ASCENT AHEAD OF THE AFOREMENTIONED TROUGH AND A GRAVITY WAVE PROPAGATING NORTHWESTWARD FROM EARLIER CONVECTION ACROSS SOUTHERN AZ. LATEST HRRR HAS ASSIMILATED THIS ACTIVITY AND SUGGESTS IT WILL TREK INTO CENTRAL AND NORTHERN AZ AS IT IS ABSORBED INTO THE DEEPER SOUTHWESTERLY FLOW LATER THIS MORNING. THEREAFTER...GLOBAL AND CONVECTIVE-ALLOWING MODELS INDICATE A WIDE RANGE OF POSSIBILITIES. CONCEPTUALLY...STRONGEST ASCENT WILL SPREAD NORTH AND EASTWARD INTO THE HIGHER ELEVATIONS OF EASTERN AZ. HOWEVER...STEADILY INCREASING PWATS AS FAR WEST AS SOUTHWESTERN MARICOPA COUNTY WARRANT A SLIGHT CHANCE OF PRECIPITATION THROUGHOUT THE DAY. GIVEN THE INCREASING MOISTURE AND DECREASING THICKNESSES...TEMPERATURES WILL BE A FEW DEGREES COOLER THAN THOSE OBSERVED WEDNESDAY. HIGH PRESSURE WILL BRIEFLY REBUILD ACROSS THE FORECAST AREA FRIDAY...RESULTING IN A WEAKER WESTERLY FLOW. CONSEQUENTLY...INCREASE IN PWATS WILL TAKE A BRIEF HIATUS ACROSS THE LOWER DESERTS AND CONVECTION WILL BE MOST CONCENTRATED ACROSS SOUTHERN AND EASTERN AZ. MODELS REMAIN CONSISTENT THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK WITH THEIR DEPICTION OF DEEPER TROPICAL MOISTURE LIFTING NORTHWARD OUT OF MEXICO AND INTO THE DESERT SOUTHWEST. ALTHOUGH NEARBY HURRICANE NORBERT WILL LIKELY NOT HAVE A DIRECT IMPACT ON OUR WEATHER...ITS INFLUENCE WILL BE FAVORABLE FOR PRECIPITATION WITHIN THE REGION. OFFICIAL NHC FORECASTS INDICATE THAT THE WEAKENING TC WILL MORE OR LESS TRACK PARALLEL TO THE BAJA PENINSULA...SUGGESTING THAT MOISTURE TRANSPORT WILL BE MAXIMIZED ACROSS PORTIONS OF AZ. MODELS SUGGEST THAT PWATS WILL APPROACH 2 INCHES SUNDAY...INCREASING THE LIKELIHOOD OF HEAVY RAIN AND FLOODING. RECENT TRENDS IN THE ECWMF ALSO SUGGEST A SOMEWHAT SLOWER ONSET OF THE DEEPER MOISTURE...WITH THE BEST CHANCE FOR PRECIPITATION OCCURRING SUNDAY AND MONDAY. HOWEVER...THE GFS PAINTS A DIFFERENT PICTURE WITH THE DEVELOPMENT OF A DRY SLOT MONDAY BETWEEN THE REMNANTS OF NORBERT AND DEEPER MOISTURE TO THE EAST. BOTTOM LINE IS THAT CONSIDERABLE UNCERTAINTY REMAINS...THOUGH IT APPEARS MORE LIKELY THAT A WIDESPREAD 1 TO 2 INCHES OF RAIN CAN BE EXPECTED FROM MARICOPA COUNTY EASTWARD THROUGH TUESDAY. && .AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL... ISOLATED SHOWERS/THUNDERSTORMS EXPECTED ACROSS SOUTH-CENTRAL ARIZONA THIS MORNING...MAINLY ACROSS HIGHER TERRAIN AREAS TO THE NORTH AND EAST OF PHOENIX...WITH SCT-BKN CLOUD DECKS AOA 10KFT. WINDS WILL CONTINUE TO FAVOR EAST-SOUTHEAST GENERALLY 10KT OR LESS...AND MAY SWITCH TO SOUTHWEST BRIEFLY FOR A COUPLE HOURS IF THERE IS SUFFICIENT CLEARING OF MID-LEVEL CLOUD DECKS LATE THIS AFTERNOON. ISOLATED SHOWER/THUNDERSTORMS ACTIVITY ENCROACHES ONCE AGAIN NEAR TERMINALS THIS EVENING...BUT UNCERTAINTY IN TIMING/COVERAGE WARRANTS LEAVING ANY MENTION OF WEATHER OUT OF THE TAFS AT THIS TIME. SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH... LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE TODAY...WITH MOSTLY CLEAR SKIES AND JUST A FEW-SCT MID LEVEL CUMULUS. WINDS SHOULD CONTINUE TO FAVOR SOUTH-SOUTHEAST GENERALLY 10KT OR LESS...EXCEPT ALONG THE LOWER COLORADO RIVER VALLEY/NEAR KBLH WHERE GUSTS UP TO 25KT WILL ACCOMPANY ADDITIONAL MOISTURE SURGE AFTER 06Z FRIDAY. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SATURDAY THROUGH WEDNESDAY... MONSOON MOISTURE WILL CONTINUE TO INCREASE AND SPREAD NORTH AND WEST REACHING THE LOWER DESERTS OF SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA BY SATURDAY. STORM CHANCES WILL CONTINUE THROUGH TUESDAY BEFORE TRENDING DOWNWARD LATE IN THE PERIOD. HUMIDITIES WILL REMAIN ELEVATED DURING THE PERIOD...WHILE TEMPERATURES TREND DOWNWARD. WINDS WILL FOLLOW FAMILIAR SUMMERTIME SLOPE-VALLEY PATTERNS BUT WITH SIGNIFICANT DISRUPTIONS DUE TO THUNDERSTORM ACTIVITY. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...HIRSCH AVIATION...MEYERS FIRE WEATHER...AJ/MEYERS
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
512 AM MST THU SEP 4 2014 .UPDATE...UPDATED AVIATION DISCUSSION. && .SYNOPSIS... MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA. SHOWERS AND THUNDERSTORMS WILL REMAIN MORE ISOLATED OVER THE HIGHER TERRAIN THROUGH FRIDAY...BUT SHOULD BECOME MORE PERIODIC AND WIDESPREAD BY THE END OF THE WEEKEND AND EARLY NEXT WEEK. HEAVY RAINFALL AND LOCALIZED FLOODING WILL BE THE PRIMARY THREATS WITH THESE STORMS LATE IN THE WEEKEND...WITH CLEARING ONLY SLOWLY OCCURRING NEXT WEEK. && .DISCUSSION... LATEST RAP STREAMLINE ANALYSIS SHOWS A WEAK TROUGH ACROSS SOUTHERN CA WITH DEEPER MOISTURE LIFTING NORTHWARD ACROSS AZ IN A SOUTHWESTERLY FLOW. ISOLATED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED EARLY THIS MORNING...MAINLY ACROSS NORTHWESTERN PORTIONS OF MARICOPA COUNTY...PRODUCING BRIEF HEAVY RAIN. GIVEN THE LACK OF ELEVATED CAPE...THE ACTIVITY IS PRESUMABLY BEING AIDED BY VORTICITY-FORCED ASCENT AHEAD OF THE AFOREMENTIONED TROUGH AND A GRAVITY WAVE PROPAGATING NORTHWESTWARD FROM EARLIER CONVECTION ACROSS SOUTHERN AZ. LATEST HRRR HAS ASSIMILATED THIS ACTIVITY AND SUGGESTS IT WILL TREK INTO CENTRAL AND NORTHERN AZ AS IT IS ABSORBED INTO THE DEEPER SOUTHWESTERLY FLOW LATER THIS MORNING. THEREAFTER...GLOBAL AND CONVECTIVE-ALLOWING MODELS INDICATE A WIDE RANGE OF POSSIBILITIES. CONCEPTUALLY...STRONGEST ASCENT WILL SPREAD NORTH AND EASTWARD INTO THE HIGHER ELEVATIONS OF EASTERN AZ. HOWEVER...STEADILY INCREASING PWATS AS FAR WEST AS SOUTHWESTERN MARICOPA COUNTY WARRANT A SLIGHT CHANCE OF PRECIPITATION THROUGHOUT THE DAY. GIVEN THE INCREASING MOISTURE AND DECREASING THICKNESSES...TEMPERATURES WILL BE A FEW DEGREES COOLER THAN THOSE OBSERVED WEDNESDAY. HIGH PRESSURE WILL BRIEFLY REBUILD ACROSS THE FORECAST AREA FRIDAY...RESULTING IN A WEAKER WESTERLY FLOW. CONSEQUENTLY...INCREASE IN PWATS WILL TAKE A BRIEF HIATUS ACROSS THE LOWER DESERTS AND CONVECTION WILL BE MOST CONCENTRATED ACROSS SOUTHERN AND EASTERN AZ. MODELS REMAIN CONSISTENT THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK WITH THEIR DEPICTION OF DEEPER TROPICAL MOISTURE LIFTING NORTHWARD OUT OF MEXICO AND INTO THE DESERT SOUTHWEST. ALTHOUGH NEARBY HURRICANE NORBERT WILL LIKELY NOT HAVE A DIRECT IMPACT ON OUR WEATHER...ITS INFLUENCE WILL BE FAVORABLE FOR PRECIPITATION WITHIN THE REGION. OFFICIAL NHC FORECASTS INDICATE THAT THE WEAKENING TC WILL MORE OR LESS TRACK PARALLEL TO THE BAJA PENINSULA...SUGGESTING THAT MOISTURE TRANSPORT WILL BE MAXIMIZED ACROSS PORTIONS OF AZ. MODELS SUGGEST THAT PWATS WILL APPROACH 2 INCHES SUNDAY...INCREASING THE LIKELIHOOD OF HEAVY RAIN AND FLOODING. RECENT TRENDS IN THE ECWMF ALSO SUGGEST A SOMEWHAT SLOWER ONSET OF THE DEEPER MOISTURE...WITH THE BEST CHANCE FOR PRECIPITATION OCCURRING SUNDAY AND MONDAY. HOWEVER...THE GFS PAINTS A DIFFERENT PICTURE WITH THE DEVELOPMENT OF A DRY SLOT MONDAY BETWEEN THE REMNANTS OF NORBERT AND DEEPER MOISTURE TO THE EAST. BOTTOM LINE IS THAT CONSIDERABLE UNCERTAINTY REMAINS...THOUGH IT APPEARS MORE LIKELY THAT A WIDESPREAD 1 TO 2 INCHES OF RAIN CAN BE EXPECTED FROM MARICOPA COUNTY EASTWARD THROUGH TUESDAY. && .AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL... ISOLATED SHOWERS/THUNDERSTORMS EXPECTED ACROSS SOUTH-CENTRAL ARIZONA THIS MORNING...MAINLY ACROSS HIGHER TERRAIN AREAS TO THE NORTH AND EAST OF PHOENIX...WITH SCT-BKN CLOUD DECKS AOA 10KFT. WINDS WILL CONTINUE TO FAVOR EAST-SOUTHEAST GENERALLY 10KT OR LESS...AND MAY SWITCH TO SOUTHWEST BRIEFLY FOR A COUPLE HOURS IF THERE IS SUFFICIENT CLEARING OF MID-LEVEL CLOUD DECKS LATE THIS AFTERNOON. ISOLATED SHOWER/THUNDERSTORMS ACTIVITY ENCROACHES ONCE AGAIN NEAR TERMINALS THIS EVENING...BUT UNCERTAINTY IN TIMING/COVERAGE WARRANTS LEAVING ANY MENTION OF WEATHER OUT OF THE TAFS AT THIS TIME. SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH... LOW LEVEL MOISTURE WILL CONTINUE TO INCREASE TODAY...WITH MOSTLY CLEAR SKIES AND JUST A FEW-SCT MID LEVEL CUMULUS. WINDS SHOULD CONTINUE TO FAVOR SOUTH-SOUTHEAST GENERALLY 10KT OR LESS...EXCEPT ALONG THE LOWER COLORADO RIVER VALLEY/NEAR KBLH WHERE GUSTS UP TO 25KT WILL ACCOMPANY ADDITIONAL MOISTURE SURGE AFTER 06Z FRIDAY. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SATURDAY THROUGH WEDNESDAY... MONSOON MOISTURE WILL CONTINUE TO INCREASE AND SPREAD NORTH AND WEST REACHING THE LOWER DESERTS OF SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA BY SATURDAY. STORM CHANCES WILL CONTINUE THROUGH TUESDAY BEFORE TRENDING DOWNWARD LATE IN THE PERIOD. HUMIDITIES WILL REMAIN ELEVATED DURING THE PERIOD...WHILE TEMPERATURES TREND DOWNWARD. WINDS WILL FOLLOW FAMILIAR SUMMERTIME SLOPE-VALLEY PATTERNS BUT WITH SIGNIFICANT DISRUPTIONS DUE TO THUNDERSTORM ACTIVITY. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...HIRSCH AVIATION...KUHLMAN FIRE WEATHER...AJ/MEYERS
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
345 AM MST THU SEP 4 2014 .SYNOPSIS... MOISTURE WILL CONTINUE TO INCREASE ACROSS THE AREA. SHOWERS AND THUNDERSTORMS WILL REMAIN MORE ISOLATED OVER THE HIGHER TERRAIN THROUGH FRIDAY...BUT SHOULD BECOME MORE PERIODIC AND WIDESPREAD BY THE END OF THE WEEKEND AND EARLY NEXT WEEK. HEAVY RAINFALL AND LOCALIZED FLOODING WILL BE THE PRIMARY THREATS WITH THESE STORMS LATE IN THE WEEKEND...WITH CLEARING ONLY SLOWLY OCCURRING NEXT WEEK. && .DISCUSSION... LATEST RAP STREAMLINE ANALYSIS SHOWS A WEAK TROUGH ACROSS SOUTHERN CA WITH DEEPER MOISTURE LIFTING NORTHWARD ACROSS AZ IN A SOUTHWESTERLY FLOW. ISOLATED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED EARLY THIS MORNING...MAINLY ACROSS NORTHWESTERN PORTIONS OF MARICOPA COUNTY...PRODUCING BRIEF HEAVY RAIN. GIVEN THE LACK OF ELEVATED CAPE...THE ACTIVITY IS PRESUMABLY BEING AIDED BY VORTICITY-FORCED ASCENT AHEAD OF THE AFOREMENTIONED TROUGH AND A GRAVITY WAVE PROPAGATING NORTHWESTWARD FROM EARLIER CONVECTION ACROSS SOUTHERN AZ. LATEST HRRR HAS ASSIMILATED THIS ACTIVITY AND SUGGESTS IT WILL TREK INTO CENTRAL AND NORTHERN AZ AS IT IS ABSORBED INTO THE DEEPER SOUTHWESTERLY FLOW LATER THIS MORNING. THEREAFTER...GLOBAL AND CONVECTIVE-ALLOWING MODELS INDICATE A WIDE RANGE OF POSSIBILITIES. CONCEPTUALLY...STRONGEST ASCENT WILL SPREAD NORTH AND EASTWARD INTO THE HIGHER ELEVATIONS OF EASTERN AZ. HOWEVER...STEADILY INCREASING PWATS AS FAR WEST AS SOUTHWESTERN MARICOPA COUNTY WARRANT A SLIGHT CHANCE OF PRECIPITATION THROUGHOUT THE DAY. GIVEN THE INCREASING MOISTURE AND DECREASING THICKNESSES...TEMPERATURES WILL BE A FEW DEGREES COOLER THAN THOSE OBSERVED WEDNESDAY. HIGH PRESSURE WILL BRIEFLY REBUILD ACROSS THE FORECAST AREA FRIDAY...RESULTING IN A WEAKER WESTERLY FLOW. CONSEQUENTLY...INCREASE IN PWATS WILL TAKE A BRIEF HIATUS ACROSS THE LOWER DESERTS AND CONVECTION WILL BE MOST CONCENTRATED ACROSS SOUTHERN AND EASTERN AZ. MODELS REMAIN CONSISTENT THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK WITH THEIR DEPICTION OF DEEPER TROPICAL MOISTURE LIFTING NORTHWARD OUT OF MEXICO AND INTO THE DESERT SOUTHWEST. ALTHOUGH NEARBY HURRICANE NORBERT WILL LIKELY NOT HAVE A DIRECT IMPACT ON OUR WEATHER...ITS INFLUENCE WILL BE FAVORABLE FOR PRECIPITATION WITHIN THE REGION. OFFICIAL NHC FORECASTS INDICATE THAT THE WEAKENING TC WILL MORE OR LESS TRACK PARALLEL TO THE BAJA PENINSULA...SUGGESTING THAT MOISTURE TRANSPORT WILL BE MAXIMIZED ACROSS PORTIONS OF AZ. MODELS SUGGEST THAT PWATS WILL APPROACH 2 INCHES SUNDAY...INCREASING THE LIKELIHOOD OF HEAVY RAIN AND FLOODING. RECENT TRENDS IN THE ECWMF ALSO SUGGEST A SOMEWHAT SLOWER ONSET OF THE DEEPER MOISTURE...WITH THE BEST CHANCE FOR PRECIPITATION OCCURRING SUNDAY AND MONDAY. HOWEVER...THE GFS PAINTS A DIFFERENT PICTURE WITH THE DEVELOPMENT OF A DRY SLOT MONDAY BETWEEN THE REMNANTS OF NORBERT AND DEEPER MOISTURE TO THE EAST. BOTTOM LINE IS THAT CONSIDERABLE UNCERTAINTY REMAINS...THOUGH IT APPEARS MORE LIKELY THAT A WIDESPREAD 1 TO 2 INCHES OF RAIN CAN BE EXPECTED FROM MARICOPA COUNTY EASTWARD THROUGH TUESDAY. && .AVIATION... SOUTH-CENTRAL ARIZONA INCLUDING KPHX...KIWA...AND KSDL... MID-LEVEL CLOUDINESS WITH DECKS DOWN TO AROUND 12K FEET WILL PERSIST THROUGH AROUND 18Z THURSDAY. SCATTERED LIGHT SHOWERS WILL AFFECT HIGHER TERRAIN AREAS TO THE NORTH AND EAST OF PHOENIX TONIGHT AND THURSDAY MORNING...WHILE EXPECTING MAINLY VIRGA AND SPRINKLES ACROSS THE LOWER DESERTS. WINDS HAVE ALREADY SWITCHED AROUND TO AN EASTERLY DIRECTION AND ARE EXPECTED TO REMAIN OUT OF THE EAST THE REST OF THE NIGHT. SHOULD SEE SOME ADDITIONAL ISOLATED SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS HIGHER TERRAIN AREAS THURSDAY AFTERNOON AND EVENING...BUT NOT EXPECTING ANY IMPACTS TO THE PHOENIX TERMINALS. SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA INCLUDING KIPL AND KBLH... MOSTLY CLEAR SKIES OVERNIGHT WITH SOME PERIODIC SCATTERED MID AND HIGH CLOUDS COMING IN FROM ARIZONA. WINDS WILL REMAIN BELOW 12 KNOTS THROUGH THE PERIOD AND GENERALLY OUT OF A SOUTHERLY DIRECTION. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... SATURDAY THROUGH WEDNESDAY... MONSOON MOISTURE WILL CONTINUE TO INCREASE AND SPREAD NORTH AND WEST REACHING THE LOWER DESERTS OF SOUTHWEST ARIZONA AND SOUTHEAST CALIFORNIA BY SATURDAY. STORM CHANCES WILL CONTINUE THROUGH TUESDAY BEFORE TRENDING DOWNWARD LATE IN THE PERIOD. HUMIDITIES WILL REMAIN ELEVATED DURING THE PERIOD...WHILE TEMPERATURES TREND DOWNWARD. WINDS WILL FOLLOW FAMILIAR SUMMERTIME SLOPE-VALLEY PATTERNS BUT WITH SIGNIFICANT DISRUPTIONS DUE TO THUNDERSTORM ACTIVITY. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...NONE. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...HIRSCH AVIATION...KUHLMAN FIRE WEATHER...AJ/MEYERS
AREA FORECAST DISCUSSION
NWS ALBANY NY
1008 PM EDT FRI SEP 5 2014 .SYNOPSIS... A FLOW OF WARM AND HUMID SOUTHERLY AIR WILL CONTINUE TO RESULT IN ABOVE NORMAL TEMPERATURES INTO SATURDAY. A COLD FRONT APPROACHING FROM THE GREAT LAKES AND SOUTHEAST CANADA WILL CROSS OUR REGION ON SATURDAY...BRINGING SHOWERS AND THUNDERSTORMS. SOME OF THE THUNDERSTORMS MAY BE STRONG TO SEVERE. MUCH COOLER AND DRIER AIR WILL MOVE IN FOR SUNDAY AND MONDAY...AS HIGH PRESSURE BUILDS IN FROM THE WEST. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 1000 PM EDT...A MUGGY EVENING CONTINUES WITH SOME HAZE AS DEWPOINTS WERE HOVERING 70F AND WIDELY SCATTERED CLOUDS. STRATUS HAS BECOME MORE PRONOUNCED INTO PORTIONS OF THE CATSKILLS...NW CT AND SOUTHERN BERKS PER THE 11U-3.9U IMAGERY. THIS WILL LIKELY SPREAD A BIT OVERNIGHT AS OUR REGION REMAINS FIRMLY ENTRENCHED IN A WARM SECTOR AHEAD OF A COLD FRONT APPROACHING FROM THE GREAT LAKES. THE IMPRESSIVE LINE OF CONVECTION IN THE VICINITY OF THE COLD FRONT WAS CROSSING LOWER ONTARIO PROVINCE AND IS NOW SHOWING SIGNS OF WEAKENING. THE LATEST MESOSCALE MODELS SUCH AS THE HRRR AND LOCAL HI RES WRF INDICATING LINES/CLUSTERS OF CONVECTION WILL APPROACH CENTRAL NY LATE THIS EVENING IT IS FORECAST TO WEAKEN FURTHER IN INTENSITY...AND BY THE TIME IT POTENTIALLY REACHES EAST CENTRAL NEW YORK LATE TONIGHT CONVECTION SHOULD DISSIPATE AS IT OUTRUNS THE FORCING ASSOCIATED WITH THE FRONT. SO WILL ONLY MENTION SLIGHT CHANCE TO LOW CHANCE POPS THROUGH THE NIGHT WEST OF THE CAPITAL REGION...WITH THE HIGHER VALUES ACROSS THE WESTERN ADIRONDACKS AND MOHAWK VALLEY. HIGHEST CONFIDENCE FOR AREAS FROM THE CAPITAL REGION EASTWARD REMAINING RAIN-FREE THROUGH SUNRISE SATURDAY. MINIMUM TEMPERATURES ONLY EXPECTED TO DROP INTO THE 60S REGION-WIDE. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... SATURDAY LOOKS TO BE A CONVECTIVELY ACTIVE DAY ACROSS MUCH OF THE AREA...AS A COLD FRONT SWEEPS FROM NORTHWEST TO SOUTHEAST DURING THE DAY. IT WILL REMAIN QUITE HUMID...SO ANY BREAKS OF SUNSHINE EARLY WILL LEAD TO RAPID DESTABILIZATION AHEAD OF THE COLD FRONT. THE BEST CHANCE FOR SOME EARLY SUNSHINE WHERE FORECAST SBCAPE VALUES COULD REACH 1500-2500 J/KG...IS FROM AROUND THE ALBANY AND SARATOGA REGIONS SOUTH AND EAST. FLOW ALOFT WILL STEADILY INCREASE THROUGH THE AFTERNOON...WHICH WILL ALLOW THE SHEAR TO STRENGTHEN AS WELL. DEEP LAYER SHEAR OF 25-35 KT AND THE APPROACHING COLD FRONT WILL LIKELY ALLOW FOR ORGANIZED CLUSTERS/BOWS TO DEVELOP...WITH DAMAGING WINDS THE MAIN THREAT AS FAIRLY WEAK MID-LEVEL LAPSE RATES SHOULD PRECLUDE A HAIL THREAT. EFFICIENT DOWNPOURS WILL ALSO BE POSSIBLE WITH ANY STORMS. HOWEVER...GIVEN THE INCREASING FLOW AND RECENT DRY GROUND CONDITIONS...WE ARE NOT EXPECTING HYDRO RELATED PROBLEMS EXCEPT FOR ISOLATED MINOR URBAN/POOR DRAINAGE FLOODING POSSIBLE. BASED ON TIMING FROM THE 12Z GUIDANCE SUITE AND LOCAL HI RES WRF...TIMING FOR CONVECTION LOOKS TO BE LATE MORNING TO EARLY AFTERNOON FOR AREAS NORTH AND WEST OF THE CAPITAL REGION...MID TO LATE AFTERNOON FOR THE CAPITAL REGION...SARATOGA REGION...SOUTHERN VERMONT AND THE CATSKILLS...AND LATE AFTERNOON TO EARLY EVENING FOR THE MID HUDSON VALLEY...TACONICS AND BERKSHIRES/LITCHFIELD HILLS. DUE TO THE TIMING...BEST CHANCES FOR SEVERE STORMS WILL BE FROM CENTRAL MOHAWK VALLEY AND SARATOGA REGION SOUTH AND EAST. THIS INCLUDES THE GREATER CAPITAL DISTRICT AND ALL POINTS SOUTH AND EAST. WILL CONTINUE TO MENTION POTENTIAL FOR DAMAGING WINDS IN THE HWO FOR THESE AREAS. DUE TO THE COLD FRONT FRONT CROSSING THE REGION...MAXIMUM TEMPERATURES WILL RANGE FROM LOWER TO MID 70S ACROSS THE ADIRONDACKS...TO LOWER TO MID 80S FROM ALBANY SOUTH AND EAST. IT WILL REMAIN HUMID FOR MUCH OF THE AREA FOR MOST OF THE DAY...WITH DEWPOINTS SPIKING IN THE UPPER 60S TO LOWER 70S. ANY LINES OF CONVECTION SHOULD BE EAST OF THE AREA BY DARK...WHICH WILL END THE SEVERE THREAT. JUST A FEW LINGERING SHOWERS WILL BE POSSIBLE FOR THE REST OF THE EVENING...ESPECIALLY ACROSS SOUTHERN AREAS. COOLER AND DRIER AIR WILL FILTER INTO THE REGION OVERNIGHT WITH A NORTHWEST BREEZE. TEMPERATURES WILL BE NOTICEABLY COOLER BY EARLY SUNDAY MORNING. DRY WEATHER AND SEASONABLY COOLER TEMPERATURES ALONG WITH PLENTY OF SUNSHINE EXPECTED FOR SUNDAY AND MONDAY...AS HIGH PRESSURE BUILDS EASTWARD AND SETTLES ACROSS THE NORTHEAST CONUS. HUMIDITY LEVELS WILL BE QUITE COMFORTABLE...WITH COOL NIGHT TIME TEMPERATURES. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... MONDAY NIGHT INTO TUESDAY...MOST OF THE REGION WILL SEE TRANQUIL CONDITIONS WITH AVERAGE TEMPERATURES ACROSS THE REGION. 05/12Z MODEL AND NUMERICAL GUIDANCE DOES SHOW A WEAK LOW PRESSURE SYSTEM WITH TROPICAL ORIGINS MOVING SLOWLY UP THE EAST COAST. MOST OF THE REGION NORTH OF THE LOWER MID HUDSON VALLEY WILL BE FAR ENOUGH REMOVED FROM THE TRACK OF THIS COASTAL LOW. THIS WILL BRING SCATTERED CLOUD COVER TO THE REGION BUT MOST REGIONS WILL REMAIN DRY WITH THE EXCEPTION OF ISOLATED POPS ACROSS OUR FAR SOUTHEASTERN AREAS CLOSER TO THE CENTER OF THE COASTAL LOW PRESSURE SYSTEM. HIGH TEMPERATURES ON TUESDAY WILL RANGE FROM THE UPPER 60S IN THE HIGH TERRAIN TO LOWER AND MID 70S ACROSS VALLEY LOCATIONS. TUESDAY NIGHT THROUGH FRIDAY...OUR NEXT WEATHER SYSTEM WILL BE MAKING ITS WAY INTO THE REGION. MOST 12Z MODELS SHOW HIGHER PROBABILITIES OF PRECIPITATION AS WE GO FROM THURSDAY INTO THURSDAY EVENING. AS AN UPPER LEVEL LOW MOVES EQUATORWARD OUT OF CANADA AS WE GO INTO THE DAY ON WEDNESDAY...A SERIES OF WEAK LOW PRESSURE IMPULSES MOVING NORTHEASTWARD AROUND A BROAD 500 HPA CIRCULATION OVER THE UPPER MIDWEST WILL PROVIDE ISOLATED TO SCATTERED SHOWERS OVER OUR REGION...MAINLY DIURNALLY DRIVEN AS TEMPERATURES BEGIN TO RISE INTO THE MID AND UPPER 70S ON WEDNESDAY WITH DEWPOINT TEMPERATURES ON THE RISE AS WELL WITH A SOUTHERLY FLOW. AS WE GO INTO THE DAY ON THURSDAY...THIS IS WHERE GLOBAL MODELS AND PROBABILISTIC GUIDANCE DIVERGE IN CONFIDENCE FROM EACH OTHER. MODELS RANGE FROM A CONTINUATION ON IMPULSES WHERE A WEAK SURFACE LOW MAY DEVELOP JUST EAST OF OUR REGION THURSDAY AFTERNOON TO A MORE POTENT SURFACE LOW DEVELOPMENT NEAR THE OHIO VALLEY UNDER A FAVORABLE POSITION WITHIN A 100 KT JET STREAK PUTTING OUR REGION IN THE WARM SECTOR FROM AN APPROACHING COLD FRONT AS WE GO INTO THURSDAY EVENING. THIS FORECAST WILL BE UPDATED AS WE GET CLOSER TO THE EVENT AND AS CONFIDENCE INCREASES. HIGH TEMPERATURES ON THURSDAY WILL REMAIN NEAR AVERAGE ON THURSDAY. AS WE APPROACH THE END OF THE WEEK ON FRIDAY...TRANQUIL WEATHER LOOKS TO RETURN TO THE REGION WITH TEMPERATURES SLIGHTLY BELOW AVERAGE WITH A WEST TO NORTHWESTERLY FLOW BEHIND THE PASSING COLD FRONT. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS THIS EVENING WITH A LIGHT WIND AT SPEEDS AROUND 10KTS OR LESS. AS DEWPOINTS ARE RATHER HIGH...NEAR 70F...AND NOCTURNAL COOLING OF THE BOUNDARY LAYER WE SHOULD SEE HAZE/MIST DEVELOP TONIGHT. LATER OVERNIGHT...LOWER LEVEL STRATUS SHOULD RESULT IN MORE MVFR CONDITIONS FOR CIGS/VIS. COULD NOT RULE OUT A PERIOD OF IFR CONDITIONS AT KGFL-KPSF. AS UPSTREAM COLD FRONT APPROACHES...THE PROBABILITIES FOR CONVECTION IMPACTING FLIGHT CONDITIONS INCREASES. WE WILL CONTINUE TO SHOW A GRADUATED APPROACH TO THE POPS WITH INITIALLY PROB30/S THEN TEMPO GROUPS WITH THE DEEPER CONVECTION. WINDS WILL GENERALLY BE FROM THE SOUTHWEST AROUND 10KTS WITH HIGHER GUSTS POSSIBLE IN THE VICINITY OF CONVECTION. OUTLOOK... SATURDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. SUNDAY TO MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. TUESDAY TO TUESDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. WEDNESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA. && .FIRE WEATHER... A FLOW OF WARM AND HUMID SOUTHERLY AIR WILL CONTINUE TO RESULT IN ABOVE NORMAL TEMPERATURES INTO SATURDAY. A COLD FRONT APPROACHING FROM THE GREAT LAKES AND SOUTHEAST CANADA WILL CROSS OUR REGION ON SATURDAY...BRINGING SHOWERS AND THUNDERSTORMS. SOME OF THE THUNDERSTORMS MAY BE STRONG TO SEVERE. MUCH COOLER AND DRIER AIR WILL MOVE IN FOR SUNDAY AND MONDAY...AS HIGH PRESSURE BUILDS IN FROM THE WEST. RELATIVE HUMIDITY VALUES WILL INCREASE TO AROUND 90 TO 100 PERCENT TONIGHT...THEN DROP TO MINIMUM VALUES OF BETWEEN 55 AND 65 PERCENT SATURDAY AFTERNOON. MAXIMUM RH VALUES SATURDAY NIGHT ARE EXPECTED TO BE AROUND 90 TO 100 PERCENT. WINDS TONIGHT ARE EXPECTED TO BE SOUTHERLY AROUND 5 TO 10 MPH. SOUTHERLY WINDS WILL SHIFT TO THE WEST BEHIND A COLD FRONT SATURDAY AFTERNOON. WINDS WILL BECOME NORTHWESTERLY AROUND 5 TO 10 MPH SATURDAY NIGHT. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE EXPECTED THROUGH AT LEAST THE NEXT 5 DAYS. SHOWERS AND THUNDERSTORMS WILL DEVELOP AND OVERSPREAD THE AREA FROM NORTHWEST TO SOUTHEAST ON SATURDAY AHEAD OF A COLD FRONT. WHILE BASIN AVERAGE RAINFALL AMOUNTS LOOK TO BE UNDER A HALF INCH...LOCALIZED RAINFALL AMOUNTS OF OVER 2 INCHES ARE POSSIBLE WHICH MAY CAUSE ISOLATED MINOR FLOODING OF URBAN/POOR DRAINAGE AREAS. DRIER WEATHER IS THEN EXPECTED SATURDAY NIGHT THROUGH TUESDAY...AS HIGH PRESSURE ASSOCIATED WITH RELATIVELY COOL AIR SETTLES OVER THE REGION. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...JPV NEAR TERM...BGM/JPV SHORT TERM...JPV LONG TERM...IAA/LFM AVIATION...IAA/BGM FIRE WEATHER...JPV HYDROLOGY...11/JPV FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT WWW.WEATHER.GOV/ALBANY
AREA FORECAST DISCUSSION
NWS ALBANY NY
753 PM EDT FRI SEP 5 2014 .SYNOPSIS... A FLOW OF WARM AND HUMID SOUTHERLY AIR WILL CONTINUE TO RESULT IN ABOVE NORMAL TEMPERATURES INTO SATURDAY. A COLD FRONT APPROACHING FROM THE GREAT LAKES AND SOUTHEAST CANADA WILL CROSS OUR REGION ON SATURDAY...BRINGING SHOWERS AND THUNDERSTORMS. SOME OF THE THUNDERSTORMS MAY BE STRONG TO SEVERE. MUCH COOLER AND DRIER AIR WILL MOVE IN FOR SUNDAY AND MONDAY...AS HIGH PRESSURE BUILDS IN FROM THE WEST. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 730 PM EDT...A MUGGY EVENING WITH SOME HAZE AS DEWPOINTS WERE AROUND 70F AND WIDELY SCATTERED CLOUDS. OUR REGION REMAINS FIRMLY ENTRENCHED IN A WARM SECTOR AHEAD OF A COLD FRONT APPROACHING FROM THE GREAT LAKES. WHILE SHOWERS HAVE DIMINISHED ACROSS OUR SOUTHERN ZONES...AN IMPRESSIVE LINE OF CONVECTION IN THE VICINITY OF THE COLD FRONT WAS CROSSING LOWER ONTARIO PROVINCE. THE MESOSCALE MODELS SUCH AS THE HRRR AND LOCAL HI RES WRF INDICATING LINES/CLUSTERS OF CONVECTION WILL APPROACH OVER THE NIAGARA FRONTIER THIS EVENING. AS THIS ACTIVITY APPROACHES CENTRAL NY LATE THIS EVENING IT IS FORECAST TO WEAKEN IN INTENSITY...AND BY THE TIME IT POTENTIALLY REACHES EAST CENTRAL NEW YORK LATE TONIGHT CONVECTION SHOULD DISSIPATE AS IT OUTRUNS THE FORCING ASSOCIATED WITH THE FRONT. SO WILL ONLY MENTION SLIGHT CHANCE TO LOW CHANCE POPS THROUGH THE NIGHT WEST OF THE CAPITAL REGION...WITH THE HIGHER VALUES ACROSS THE WESTERN ADIRONDACKS AND MOHAWK VALLEY. HIGHEST CONFIDENCE FOR AREAS FROM THE CAPITAL REGION EASTWARD REMAINING RAIN-FREE THROUGH SUNRISE SATURDAY. MINIMUM TEMPERATURES ONLY EXPECTED TO DROP INTO THE 60S REGION-WIDE. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... SATURDAY LOOKS TO BE A CONVECTIVELY ACTIVE DAY ACROSS MUCH OF THE AREA...AS A COLD FRONT SWEEPS FROM NORTHWEST TO SOUTHEAST DURING THE DAY. IT WILL REMAIN QUITE HUMID...SO ANY BREAKS OF SUNSHINE EARLY WILL LEAD TO RAPID DESTABILIZATION AHEAD OF THE COLD FRONT. THE BEST CHANCE FOR SOME EARLY SUNSHINE WHERE FORECAST SBCAPE VALUES COULD REACH 1500-2500 J/KG...IS FROM AROUND THE ALBANY AND SARATOGA REGIONS SOUTH AND EAST. FLOW ALOFT WILL STEADILY INCREASE THROUGH THE AFTERNOON...WHICH WILL ALLOW THE SHEAR TO STRENGTHEN AS WELL. DEEP LAYER SHEAR OF 25-35 KT AND THE APPROACHING COLD FRONT WILL LIKELY ALLOW FOR ORGANIZED CLUSTERS/BOWS TO DEVELOP...WITH DAMAGING WINDS THE MAIN THREAT AS FAIRLY WEAK MID-LEVEL LAPSE RATES SHOULD PRECLUDE A HAIL THREAT. EFFICIENT DOWNPOURS WILL ALSO BE POSSIBLE WITH ANY STORMS. HOWEVER...GIVEN THE INCREASING FLOW AND RECENT DRY GROUND CONDITIONS...WE ARE NOT EXPECTING HYDRO RELATED PROBLEMS EXCEPT FOR ISOLATED MINOR URBAN/POOR DRAINAGE FLOODING POSSIBLE. BASED ON TIMING FROM THE 12Z GUIDANCE SUITE AND LOCAL HI RES WRF...TIMING FOR CONVECTION LOOKS TO BE LATE MORNING TO EARLY AFTERNOON FOR AREAS NORTH AND WEST OF THE CAPITAL REGION...MID TO LATE AFTERNOON FOR THE CAPITAL REGION...SARATOGA REGION...SOUTHERN VERMONT AND THE CATSKILLS...AND LATE AFTERNOON TO EARLY EVENING FOR THE MID HUDSON VALLEY...TACONICS AND BERKSHIRES/LITCHFIELD HILLS. DUE TO THE TIMING...BEST CHANCES FOR SEVERE STORMS WILL BE FROM CENTRAL MOHAWK VALLEY AND SARATOGA REGION SOUTH AND EAST. THIS INCLUDES THE GREATER CAPITAL DISTRICT AND ALL POINTS SOUTH AND EAST. WILL CONTINUE TO MENTION POTENTIAL FOR DAMAGING WINDS IN THE HWO FOR THESE AREAS. DUE TO THE COLD FRONT FRONT CROSSING THE REGION...MAXIMUM TEMPERATURES WILL RANGE FROM LOWER TO MID 70S ACROSS THE ADIRONDACKS...TO LOWER TO MID 80S FROM ALBANY SOUTH AND EAST. IT WILL REMAIN HUMID FOR MUCH OF THE AREA FOR MOST OF THE DAY...WITH DEWPOINTS SPIKING IN THE UPPER 60S TO LOWER 70S. ANY LINES OF CONVECTION SHOULD BE EAST OF THE AREA BY DARK...WHICH WILL END THE SEVERE THREAT. JUST A FEW LINGERING SHOWERS WILL BE POSSIBLE FOR THE REST OF THE EVENING...ESPECIALLY ACROSS SOUTHERN AREAS. COOLER AND DRIER AIR WILL FILTER INTO THE REGION OVERNIGHT WITH A NORTHWEST BREEZE. TEMPERATURES WILL BE NOTICEABLY COOLER BY EARLY SUNDAY MORNING. DRY WEATHER AND SEASONABLY COOLER TEMPERATURES ALONG WITH PLENTY OF SUNSHINE EXPECTED FOR SUNDAY AND MONDAY...AS HIGH PRESSURE BUILDS EASTWARD AND SETTLES ACROSS THE NORTHEAST CONUS. HUMIDITY LEVELS WILL BE QUITE COMFORTABLE...WITH COOL NIGHT TIME TEMPERATURES. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... MONDAY NIGHT INTO TUESDAY...MOST OF THE REGION WILL SEE TRANQUIL CONDITIONS WITH AVERAGE TEMPERATURES ACROSS THE REGION. 05/12Z MODEL AND NUMERICAL GUIDANCE DOES SHOW A WEAK LOW PRESSURE SYSTEM WITH TROPICAL ORIGINS MOVING SLOWLY UP THE EAST COAST. MOST OF THE REGION NORTH OF THE LOWER MID HUDSON VALLEY WILL BE FAR ENOUGH REMOVED FROM THE TRACK OF THIS COASTAL LOW. THIS WILL BRING SCATTERED CLOUD COVER TO THE REGION BUT MOST REGIONS WILL REMAIN DRY WITH THE EXCEPTION OF ISOLATED POPS ACROSS OUR FAR SOUTHEASTERN AREAS CLOSER TO THE CENTER OF THE COASTAL LOW PRESSURE SYSTEM. HIGH TEMPERATURES ON TUESDAY WILL RANGE FROM THE UPPER 60S IN THE HIGH TERRAIN TO LOWER AND MID 70S ACROSS VALLEY LOCATIONS. TUESDAY NIGHT THROUGH FRIDAY...OUR NEXT WEATHER SYSTEM WILL BE MAKING ITS WAY INTO THE REGION. MOST 12Z MODELS SHOW HIGHER PROBABILITIES OF PRECIPITATION AS WE GO FROM THURSDAY INTO THURSDAY EVENING. AS AN UPPER LEVEL LOW MOVES EQUATORWARD OUT OF CANADA AS WE GO INTO THE DAY ON WEDNESDAY...A SERIES OF WEAK LOW PRESSURE IMPULSES MOVING NORTHEASTWARD AROUND A BROAD 500 HPA CIRCULATION OVER THE UPPER MIDWEST WILL PROVIDE ISOLATED TO SCATTERED SHOWERS OVER OUR REGION...MAINLY DIURNALLY DRIVEN AS TEMPERATURES BEGIN TO RISE INTO THE MID AND UPPER 70S ON WEDNESDAY WITH DEWPOINT TEMPERATURES ON THE RISE AS WELL WITH A SOUTHERLY FLOW. AS WE GO INTO THE DAY ON THURSDAY...THIS IS WHERE GLOBAL MODELS AND PROBABILISTIC GUIDANCE DIVERGE IN CONFIDENCE FROM EACH OTHER. MODELS RANGE FROM A CONTINUATION ON IMPULSES WHERE A WEAK SURFACE LOW MAY DEVELOP JUST EAST OF OUR REGION THURSDAY AFTERNOON TO A MORE POTENT SURFACE LOW DEVELOPMENT NEAR THE OHIO VALLEY UNDER A FAVORABLE POSITION WITHIN A 100 KT JET STREAK PUTTING OUR REGION IN THE WARM SECTOR FROM AN APPROACHING COLD FRONT AS WE GO INTO THURSDAY EVENING. THIS FORECAST WILL BE UPDATED AS WE GET CLOSER TO THE EVENT AND AS CONFIDENCE INCREASES. HIGH TEMPERATURES ON THURSDAY WILL REMAIN NEAR AVERAGE ON THURSDAY. AS WE APPROACH THE END OF THE WEEK ON FRIDAY...TRANQUIL WEATHER LOOKS TO RETURN TO THE REGION WITH TEMPERATURES SLIGHTLY BELOW AVERAGE WITH A WEST TO NORTHWESTERLY FLOW BEHIND THE PASSING COLD FRONT. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS THIS EVENING WITH A LIGHT WIND AT SPEEDS AROUND 10KTS OR LESS. AS DEWPOINTS ARE RATHER HIGH...NEAR 70F...AND NOCTURNAL COOLING OF THE BOUNDARY LAYER WE SHOULD SEE HAZE/MIST DEVELOP TONIGHT. LATER OVERNIGHT...LOWER LEVEL STRATUS SHOULD RESULT IN MORE MVFR CONDITIONS FOR CIGS/VIS. COULD NOT RULE OUT A PERIOD OF IFR CONDITIONS AT KGFL-KPSF. AS UPSTREAM COLD FRONT APPROACHES...THE PROBABILITIES FOR CONVECTION IMPACTING FLIGHT CONDITIONS INCREASES. WE WILL CONTINUE TO SHOW A GRADUATED APPROACH TO THE POPS WITH INITIALLY PROB30/S THEN TEMPO GROUPS WITH THE DEEPER CONVECTION. WINDS WILL GENERALLY BE FROM THE SOUTHWEST AROUND 10KTS WITH HIGHER GUSTS POSSIBLE IN THE VICINITY OF CONVECTION. OUTLOOK... SATURDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. SUNDAY TO MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. TUESDAY TO TUESDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. WEDNESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA. && .FIRE WEATHER... A FLOW OF WARM AND HUMID SOUTHERLY AIR WILL CONTINUE TO RESULT IN ABOVE NORMAL TEMPERATURES INTO SATURDAY. A COLD FRONT APPROACHING FROM THE GREAT LAKES AND SOUTHEAST CANADA WILL CROSS OUR REGION ON SATURDAY...BRINGING SHOWERS AND THUNDERSTORMS. SOME OF THE THUNDERSTORMS MAY BE STRONG TO SEVERE. MUCH COOLER AND DRIER AIR WILL MOVE IN FOR SUNDAY AND MONDAY...AS HIGH PRESSURE BUILDS IN FROM THE WEST. RELATIVE HUMIDITY VALUES WILL INCREASE TO AROUND 90 TO 100 PERCENT TONIGHT...THEN DROP TO MINIMUM VALUES OF BETWEEN 55 AND 65 PERCENT SATURDAY AFTERNOON. MAXIMUM RH VALUES SATURDAY NIGHT ARE EXPECTED TO BE AROUND 90 TO 100 PERCENT. WINDS TONIGHT ARE EXPECTED TO BE SOUTHERLY AROUND 5 TO 10 MPH. SOUTHERLY WINDS WILL SHIFT TO THE WEST BEHIND A COLD FRONT SATURDAY AFTERNOON. WINDS WILL BECOME NORTHWESTERLY AROUND 5 TO 10 MPH SATURDAY NIGHT. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE EXPECTED THROUGH AT LEAST THE NEXT 5 DAYS. SHOWERS AND THUNDERSTORMS WILL DEVELOP AND OVERSPREAD THE AREA FROM NORTHWEST TO SOUTHEAST ON SATURDAY AHEAD OF A COLD FRONT. WHILE BASIN AVERAGE RAINFALL AMOUNTS LOOK TO BE UNDER A HALF INCH...LOCALIZED RAINFALL AMOUNTS OF OVER 2 INCHES ARE POSSIBLE WHICH MAY CAUSE ISOLATED MINOR FLOODING OF URBAN/POOR DRAINAGE AREAS. DRIER WEATHER IS THEN EXPECTED SATURDAY NIGHT THROUGH TUESDAY...AS HIGH PRESSURE ASSOCIATED WITH RELATIVELY COOL AIR SETTLES OVER THE REGION. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...JPV NEAR TERM...BGM/JPV SHORT TERM...JPV LONG TERM...IAA/LFM AVIATION...IAA/BGM FIRE WEATHER...JPV HYDROLOGY...11/JPV FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT WWW.WEATHER.GOV/ALBANY
AREA FORECAST DISCUSSION
NWS NEW YORK NY
441 PM EDT THU SEP 4 2014 .SYNOPSIS... HIGH PRESSURE OVER THE AREA THROUGH TONIGHT WILL SHIFT OFFSHORE FRIDAY INTO FRIDAY NIGHT AS A COLD FRONT APPROACHES FROM THE WEST. THE COLD FRONT WILL MOVE ACROSS ON SATURDAY...THEN HIGH PRESSURE WILL BUILD INTO THE NORTHEAST THROUGH EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... SCT-BKN CU OVER INTERIOR SECTIONS NORTH/WEST OF NYC AND ALONG THE SEA BREEZE FRONT ON LONG ISLAND SHOULD DISSIPATE THIS EVENING... LEAVING MAINLY CLEAR SKIES FOR THE REST OF TONIGHT. BOTH THE 12Z NAM AND 17Z RAP ARE SHOWING LOW STRATUS AND/OR FOG DEVELOPMENT TOWARD DAYBREAK CLOSE TO LONG ISLAND VIA INCREASED LOW LEVEL MOISTURE IN ONSHORE FLOW AND COOLING BENEATH A SFC-BASED INVERSION. ATTM SUSPECT NAM LOW LEVEL MOISTURE IS OVERDONE...SO HAVE SIDED MORE WITH THE RAP WITH AT LEAST PTCLDY SKIES THERE LATE. EXPECT LOWS IN THE UPPER 50S IN THE LONG ISLAND PINE BARRENS AND SOME INTERIOR VALLEYS...60S MOST ELSEWHERE...AND LOWER 70S IN NYC. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... EXPECT MAINLY DRY WX AS THE HIGH SHIFTS OFFSHORE. PRESENCE OF A WEAK SFC TROUGH IN THE WAKE OF THE DEPARTING HIGH...WEAK LOW LEVEL WAA...AND APPROACH OF MID LEVEL SHORTWAVES FROM THE WEST AND SOUTHWEST MAY SPARK ISOLD SHOWERS LATE FRI NIGHT. WITH CONTINUED ONSHORE FLOW THERE SHOULD BE A BETTER CHANCE FOR LOW CLOUDS AND FOG TO DEVELOP LATE AT NIGHT. TEMPS ON FRI WITH ONSHORE FLOW AND MORE IN THE WAY OF CLOUDS SHOULD BE CLOSE TO OR ONLY SLIGHTLY LOWER THAN THOSE OF TODAY...WITH UPPER 70S FOR COASTAL SE CT AND 80S ELSEWHERE. LOWS FRI NIGHT SHOULD BE IN THE MID/UPPER 60S INLAND...AND LOWER 70S IN NYC METRO AND LONG ISLAND. THERE IS A LOW RISK OF RIP CURRENTS AT THE OCEAN BEACHES FOR MOST OF FRIDAY...BUT IT MAY BECOME BRIEFLY MODERATE LATE IN THE DAY AND EVENING WITH SEABREEZE DEVELOPMENT. && .LONG TERM /SATURDAY THROUGH THURSDAY/... DEEP SW FLOW WILL USHER A HOT AND HUMID AIR MASS AHEAD OF A COLD FRONT ACROSS THE REGION ON SATURDAY WITH SFC DEW POINTS CLIMBING TO NEAR 70 AND HIGH TEMPS IN THE UPPER 80S TO AROUND 90. THIS WILL RESULT IN A HEAT INDEX IN THE LOWER TO MID 90S. IN ADDITION...PW WILL APPROACH 2 INCHES. AS A RESULT...AS COLD FRONT APPROACHES FROM THE WEST...THERE WILL BE SUFFICIENT ENERGY AND MOISTURE FOR SHOWERS AND THUNDERSTORMS...WITH ACTIVITY INCREASING THROUGH THE AFTERNOON. HEAVY RAIN...GUSTY WINDS...AND HAIL WILL BE POSSIBLE WITH THE STRONGER STORMS. WILL KEEP POPS CAPPED AT LIKELY FOR NOW...IN LINE WITH THE LATEST MODEL GUIDANCE. COLD FRONT PUSHES THROUGH THE REGION FROM WEST TO EAST SATURDAY NIGHT...AND SHOWERS/THUNDERSTORMS WILL TAPER OFF TOWARDS DAYBREAK SUNDAY. A MUCH DRYER AIR MASS BUILDS INTO THE REGION WITH SFC DEWPOINTS DROPPING INTO THE 50S BY SUNDAY AFTERNOON...AND HIGHS WILL FALL TO LEVELS A FEW DEGREES BELOW NORMAL...IN THE MID TO UPPER 70S. HIGH PRES BUILDS INTO THE REGION MONDAY AND TUESDAY WITH DRY CONDS...AND THEN MOVES OFFSHORE TUESDAY NIGHT. AS LOW PRES OVER THE MIDWEST APPROACHES...A WARM FRONT WILL LIFT NORTH INTO THE REGION ON WEDNESDAY. UNSETTLED WEATHER POSSIBLE FOR WEDNESDAY AND THURSDAY OF NEXT WEEK. TEMPS WILL AVERAGE TO NEAR NORMAL LEVELS DURING THIS TIME....GENERALLY IN THE 70S. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... HIGH PRESSURE SLIDES OFFSHORE TONIGHT. MAINLY VFR THROUGH THE TAF PERIOD AT AREA TERMINALS. SEA BREEZE WILL AFFECT ALL BUT KSWF THROUGH THIS EVENING. THE FLOW THEN BECOMES LIGHT SSW-SW THROUGHOUT...THEN LIGHT AND VARIABLE THROUGHOUT BY AROUND MIDNIGHT TONIGHT. THERE IS THE POSSIBILITY OF MVFR FOG MOVING IN FOR ISOLATED AREAS OUTSIDE THE CITY TERMINALS...MAINLY FOR KSWF AND KHPN. AS OF RIGHT NOW HOWEVER...DO NOT THINK IT WILL BE PREVAILING. THERE IS A LOW CHANCE THAT IT CAN MAKE ITS WAY INTO KEWR. TIMING OF ANY FOG WOULD BE 09Z OR AFTER...AND BURN OFF AN HOUR OR TWO AFTER SUNRISE FRIDAY...THROUGH 13Z. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. KLGA FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. KEWR FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. LOW CHANCE OF TEMPO BR LIMITING VIS TO 6SM BETWEEN 10Z AND 13Z. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. LOW CHANCE OF TEMPO BR LIMITING VIS TO 6SM BETWEEN 10Z AND 13Z. KHPN FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. TEMPO BR LIMITING VIS TO 5SM OR LOWER BETWEEN 09Z AND 13Z. KISP FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. .OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... .FRIDAY AFTN...MAINLY VFR. ISOLD SHRA/TSTM POSSIBLE N/W OF CITY TERMINALS. .FRIDAY NIGHT...MVFR OR LOWER POSSIBLE IN ANY LOW CLOUDS AND/OR FOG. SLIGHT CHANCE SHRA/TSTM W OF CITY TERMINALS. .SATURDAY TO SATURDAY NIGHT...MVFR OR LOWER POSSIBLE IN SCT- NUMEROUS SHRA/TSTMS. LOW CLOUDS AND/OR FOG POSSIBLE EARLY IN THE MORNING. SW-W WINDS G20+ KT POSSIBLE SATURDAY...SHIFTING TO THE NW-N SATURDAY NIGHT. .SUNDAY-MONDAY...VFR. E WINDS G20KT POSSIBLE IN THE AFTERNOON ON MONDAY. .TUE...VFR. && .MARINE... DEPARTING HIGH PRESSURE WILL KEEP SUB-SCA CONDITIONS IN PLACE THROUGH FRI NIGHT. OCNL GUSTS TO 25 KT ARE POSSIBLE ON SAT AS THE PRES GRADIENT TIGHTENS WITH THE APPROACH AND PASSAGE OF A COLD FRONT. HIGH PRES THEN BUILDS OVER THE WATERS FOR THE START OF THE NEW WEEK. A PERSISTENT EASTERLY FLOW WILL DEVELOP ON THE WATERS...POSSIBLY PUSHING OCEAN SEAS CLOSE TO SCA LEVELS BY THE MIDDLE OF THE NEW WORK WEEK. && .HYDROLOGY... SHOWERS AND THUNDERSTORMS ARE LIKELY SAT INTO SAT NIGHT. STRONGER STORMS COULD PRODUCE HEAVY RAIN AND LOCALIZED FLOODING OF URBAN/POOR DRAINAGE AREAS AND SMALL STREAMS. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...GOODMAN/MPS NEAR TERM...GOODMAN/MPS SHORT TERM...GOODMAN LONG TERM...MPS AVIATION...JP MARINE...GOODMAN/MPS HYDROLOGY...MPS
AREA FORECAST DISCUSSION
NWS NEW YORK NY
434 PM EDT THU SEP 4 2014 .SYNOPSIS... HIGH PRESSURE OVER THE AREA THROUGH TONIGHT WILL SHIFT OFFSHORE FRIDAY INTO FRIDAY NIGHT AS A COLD FRONT APPROACHES FROM THE WEST. THE COLD FRONT WILL MOVE ACROSS ON SATURDAY...THEN HIGH PRESSURE WILL BUILD INTO THE NORTHEAST THROUGH EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... SCT-BKN CU OVER INTERIOR SECTIONS NORTH/WEST OF NYC AND ALONG THE SEA BREEZE FRONT ON LONG ISLAND SHOULD DISSIPATE THIS EVENING... LEAVING MAINLY CLEAR SKIES FOR THE REST OF TONIGHT. BOTH THE 12Z NAM AND 17Z RAP ARE SHOWING LOW STRATUS AND/OR FOG DEVELOPMENT TOWARD DAYBREAK CLOSE TO LONG ISLAND VIA INCREASED LOW LEVEL MOISTURE IN ONSHORE FLOW AND COOLING BENEATH A SFC-BASED INVERSION. ATTM SUSPECT NAM LOW LEVEL MOISTURE IS OVERDONE...SO HAVE SIDED MORE WITH THE RAP WITH AT LEAST PTCLDY SKIES THERE LATE. EXPECT LOWS IN THE UPPER 50S IN THE LONG ISLAND PINE BARRENS AND SOME INTERIOR VALLEYS...60S MOST ELSEWHERE...AND LOWER 70S IN NYC. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... EXPECT MAINLY DRY WX AS THE HIGH SHIFTS OFFSHORE. PRESENCE OF A WEAK SFC TROUGH IN THE WAKE OF THE DEPARTING HIGH...WEAK LOW LEVEL WAA...AND APPROACH OF MID LEVEL SHORTWAVES FROM THE WEST AND SOUTHWEST MAY SPARK ISOLD SHOWERS LATE FRI NIGHT. WITH CONTINUED ONSHORE FLOW THERE SHOULD BE A BETTER CHANCE FOR LOW CLOUDS AND FOG TO DEVELOP LATE AT NIGHT. TEMPS ON FRI WITH ONSHORE FLOW AND MORE IN THE WAY OF CLOUDS SHOULD BE CLOSE TO OR ONLY SLIGHTLY LOWER THAN THOSE OF TODAY...WITH UPPER 70S FOR COASTAL SE CT AND 80S ELSEWHERE. LOWS FRI NIGHT SHOULD BE IN THE MID/UPPER 60S INLAND...AND LOWER 70S IN NYC METRO AND LONG ISLAND. && .LONG TERM /SATURDAY THROUGH THURSDAY/... DEEP SW FLOW WILL USHER A HOT AND HUMID AIR MASS AHEAD OF A COLD FRONT ACROSS THE REGION ON SATURDAY WITH SFC DEW POINTS CLIMBING TO NEAR 70 AND HIGH TEMPS IN THE UPPER 80S TO AROUND 90. THIS WILL RESULT IN A HEAT INDEX IN THE LOWER TO MID 90S. IN ADDITION...PW WILL APPROACH 2 INCHES. AS A RESULT...AS COLD FRONT APPROACHES FROM THE WEST...THERE WILL BE SUFFICIENT ENERGY AND MOISTURE FOR SHOWERS AND THUNDERSTORMS...WITH ACTIVITY INCREASING THROUGH THE AFTERNOON. HEAVY RAIN...GUSTY WINDS...AND HAIL WILL BE POSSIBLE WITH THE STRONGER STORMS. WILL KEEP POPS CAPPED AT LIKELY FOR NOW...IN LINE WITH THE LATEST MODEL GUIDANCE. COLD FRONT PUSHES THROUGH THE REGION FROM WEST TO EAST SATURDAY NIGHT...AND SHOWERS/THUNDERSTORMS WILL TAPER OFF TOWARDS DAYBREAK SUNDAY. A MUCH DRYER AIR MASS BUILDS INTO THE REGION WITH SFC DEWPOINTS DROPPING INTO THE 50S BY SUNDAY AFTERNOON...AND HIGHS WILL FALL TO LEVELS A FEW DEGREES BELOW NORMAL...IN THE MID TO UPPER 70S. HIGH PRES BUILDS INTO THE REGION MONDAY AND TUESDAY WITH DRY CONDS...AND THEN MOVES OFFSHORE TUESDAY NIGHT. AS LOW PRES OVER THE MIDWEST APPROACHES...A WARM FRONT WILL LIFT NORTH INTO THE REGION ON WEDNESDAY. UNSETTLED WEATHER POSSIBLE FOR WEDNESDAY AND THURSDAY OF NEXT WEEK. TEMPS WILL AVERAGE TO NEAR NORMAL LEVELS DURING THIS TIME....GENERALLY IN THE 70S. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... HIGH PRESSURE SLIDES OFFSHORE TONIGHT. MAINLY VFR THROUGH THE TAF PERIOD AT AREA TERMINALS. SEA BREEZE WILL AFFECT ALL BUT KSWF THROUGH THIS EVENING. THE FLOW THEN BECOMES LIGHT SSW-SW THROUGHOUT...THEN LIGHT AND VARIABLE THROUGHOUT BY AROUND MIDNIGHT TONIGHT. THERE IS THE POSSIBILITY OF MVFR FOG MOVING IN FOR ISOLATED AREAS OUTSIDE THE CITY TERMINALS...MAINLY FOR KSWF AND KHPN. AS OF RIGHT NOW HOWEVER...DO NOT THINK IT WILL BE PREVAILING. THERE IS A LOW CHANCE THAT IT CAN MAKE ITS WAY INTO KEWR. TIMING OF ANY FOG WOULD BE 09Z OR AFTER...AND BURN OFF AN HOUR OR TWO AFTER SUNRISE FRIDAY...THROUGH 13Z. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. KLGA FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. KEWR FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. LOW CHANCE OF TEMPO BR LIMITING VIS TO 6SM BETWEEN 10Z AND 13Z. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. LOW CHANCE OF TEMPO BR LIMITING VIS TO 6SM BETWEEN 10Z AND 13Z. KHPN FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. TEMPO BR LIMITING VIS TO 5SM OR LOWER BETWEEN 09Z AND 13Z. KISP FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. .OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... .FRIDAY AFTN...MAINLY VFR. ISOLD SHRA/TSTM POSSIBLE N/W OF CITY TERMINALS. .FRIDAY NIGHT...MVFR OR LOWER POSSIBLE IN ANY LOW CLOUDS AND/OR FOG. SLIGHT CHANCE SHRA/TSTM W OF CITY TERMINALS. .SATURDAY TO SATURDAY NIGHT...MVFR OR LOWER POSSIBLE IN SCT- NUMEROUS SHRA/TSTMS. LOW CLOUDS AND/OR FOG POSSIBLE EARLY IN THE MORNING. SW-W WINDS G20+ KT POSSIBLE SATURDAY...SHIFTING TO THE NW-N SATURDAY NIGHT. .SUNDAY-MONDAY...VFR. E WINDS G20KT POSSIBLE IN THE AFTERNOON ON MONDAY. .TUE...VFR. && .MARINE... DEPARTING HIGH PRESSURE WILL KEEP SUB-SCA CONDITIONS IN PLACE THROUGH FRI NIGHT. OCNL GUSTS TO 25 KT ARE POSSIBLE ON SAT AS THE PRES GRADIENT TIGHTENS WITH THE APPROACH AND PASSAGE OF A COLD FRONT. HIGH PRES THEN BUILDS OVER THE WATERS FOR THE START OF THE NEW WEEK. A PERSISTENT EASTERLY FLOW WILL DEVELOP ON THE WATERS...POSSIBLY PUSHING OCEAN SEAS CLOSE TO SCA LEVELS BY THE MIDDLE OF THE NEW WORK WEEK. && .HYDROLOGY... SHOWERS AND THUNDERSTORMS ARE LIKELY SAT INTO SAT NIGHT. STRONGER STORMS COULD PRODUCE HEAVY RAIN AND LOCALIZED FLOODING OF URBAN/POOR DRAINAGE AREAS AND SMALL STREAMS. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...GOODMAN/MPS NEAR TERM...GOODMAN/MPS SHORT TERM...GOODMAN LONG TERM...MPS AVIATION...JP MARINE...GOODMAN/MPS HYDROLOGY...MPS
AREA FORECAST DISCUSSION
NWS NEW YORK NY
345 PM EDT THU SEP 4 2014 .SYNOPSIS... HIGH PRESSURE OVER THE AREA THROUGH TONIGHT WILL SHIFT OFFSHORE FRIDAY INTO FRIDAY NIGHT AS A COLD FRONT APPROACHES FROM THE WEST. THE COLD FRONT WILL MOVE ACROSS ON SATURDAY...THEN HIGH PRESSURE WILL BUILD INTO THE NORTHEAST THROUGH EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... SCT-BKN CU OVER INTERIOR SECTIONS NORTH/WEST OF NYC AND ALONG THE SEA BREEZE FRONT ON LONG ISLAND SHOULD DISSIPATE THIS EVENING... LEAVING MAINLY CLEAR SKIES FOR THE REST OF TONIGHT. BOTH THE 12Z NAM AND 17Z RAP ARE SHOWING LOW STRATUS AND/OR FOG DEVELOPMENT TOWARD DAYBREAK CLOSE TO LONG ISLAND VIA INCREASED LOW LEVEL MOISTURE IN ONSHORE FLOW AND COOLING BENEATH A SFC-BASED INVERSION. ATTM SUSPECT NAM LOW LEVEL MOISTURE IS OVERDONE...SO HAVE SIDED MORE WITH THE RAP WITH AT LEAST PTCLDY SKIES THERE LATE. EXPECT LOWS IN THE UPPER 50S IN THE LONG ISLAND PINE BARRENS AND SOME INTERIOR VALLEYS...60S MOST ELSEWHERE...AND LOWER 70S IN NYC. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... EXPECT MAINLY DRY WX AS THE HIGH SHIFTS OFFSHORE. PRESENCE OF A WEAK SFC TROUGH IN THE WAKE OF THE DEPARTING HIGH...WEAK LOW LEVEL WAA...AND APPROACH OF MID LEVEL SHORTWAVES FROM THE WEST AND SOUTHWEST MAY SPARK ISOLD SHOWERS LATE FRI NIGHT. WITH CONTINUED ONSHORE FLOW THERE SHOULD BE A BETTER CHANCE FOR LOW CLOUDS AND FOG TO DEVELOP LATE AT NIGHT. TEMPS ON FRI WITH ONSHORE FLOW AND MORE IN THE WAY OF CLOUDS SHOULD BE CLOSE TO OR ONLY SLIGHTLY LOWER THAN THOSE OF TODAY...WITH UPPER 70S FOR COASTAL SE CT AND 80S ELSEWHERE. LOWS FRI NIGHT SHOULD BE IN THE MID/UPPER 60S INLAND...AND LOWER 70S IN NYC METRO AND LONG ISLAND. && .LONG TERM /SATURDAY THROUGH THURSDAY/... DEEP SW FLOW WILL USHER A HOT AND HUMID AIR MASS AHEAD OF A COLD FRONT ACROSS THE REGION ON SATURDAY WITH SFC DEW POINTS CLIMBING TO NEAR 70 AND HIGH TEMPS IN THE UPPER 80S TO AROUND 90. THIS WILL RESULT IN A HEAT INDEX IN THE LOWER TO MID 90S. IN ADDITION...PW WILL APPROACH 2 INCHES. AS A RESULT...AS COLD FRONT APPROACHES FROM THE WEST...THERE WILL BE SUFFICIENT ENERGY AND MOISTURE FOR SHOWERS AND THUNDERSTORMS...WITH ACTIVITY INCREASING THROUGH THE AFTERNOON. HEAVY RAIN...GUSTY WINDS...AND HAIL WILL BE POSSIBLE WITH THE STRONGER STORMS. WILL KEEP POPS CAPPED AT LIKELY FOR NOW...IN LINE WITH THE LATEST MODEL GUIDANCE. COLD FRONT PUSHES THROUGH THE REGION FROM WEST TO EAST SATURDAY NIGHT...AND SHOWERS/THUNDERSTORMS WILL TAPER OFF TOWARDS DAYBREAK SUNDAY. A MUCH DRYER AIR MASS BUILDS INTO THE REGION WITH SFC DEWPOINTS DROPPING INTO THE 50S BY SUNDAY AFTERNOON...AND HIGHS WILL FALL TO LEVELS A FEW DEGREES BELOW NORMAL...IN THE MID TO UPPER 70S. HIGH PRES BUILDS INTO THE REGION MONDAY AND TUESDAY WITH DRY CONDS...AND THEN MOVES OFFSHORE TUESDAY NIGHT. AS LOW PRES OVER THE MIDWEST APPROACHES...A WARM FRONT WILL LIFT NORTH INTO THE REGION ON WEDNESDAY. UNSETTLED WEATHER POSSIBLE FOR WEDNESDAY AND THURSDAY OF NEXT WEEK. TEMPS WILL AVERAGE TO NEAR NORMAL LEVELS DURING THIS TIME....GENERALLY IN THE 70S. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... HIGH PRESSURE OVER THE AREA THIS MORNING...SLIDES OFFSHORE INTO TONIGHT. VFR THROUGH THE TAF PERIOD AT AREA TERMINALS. SEA BREEZE HAS ALREADY MOVED THROUGH CITY TERMINALS AND WILL AFFECT ALL BUT KSWF TODAY WHERE A LIGHT SW FLOW HAS DEVELOPED. FLOW BECOMES LIGHT OUT OF THE SSW-SW THROUGHOUT BY EARLY EVENING...THEN LIGHT AND VARIABLE THROUGHOUT BY AROUND MIDNIGHT TONIGHT. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. KLGA FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. KEWR FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. LOW CHANCE OF TEMPO BR LIMITING VIS TO 6SM BETWEEN 10Z AND 13Z. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. LOW CHANCE OF TEMPO BR LIMITING VIS TO 6SM BETWEEN 10Z AND 13Z. KHPN FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. TEMPO BR LIMITING VIS TO 5SM OR LOWER BETWEEN 09Z AND 13Z. KISP FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. .OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY... .FRIDAY...MVFR FOG POSSIBLE INLAND TERMINALS EARLY. ISOLD SHRA/TSTM POSSIBLE N/W OF CITY TERMINALS. .FRIDAY NIGHT...MVFR OR LOWER POSSIBLE IN ANY LOW CLOUDS AND/OR FOG. SLIGHT CHANCE SHRA/TSTM W OF CITY TERMINALS. .SATURDAY TO SATURDAY NIGHT...MVFR OR LOWER POSSIBLE IN SCT- NUMEROUS SHRA/TSTMS. LOW CLOUDS AND/OR FOG POSSIBLE EARLY IN THE MORNING. SW-W WINDS G20+ KT POSSIBLE SATURDAY...SHIFTING TO THE NW-N SATURDAY NIGHT. .SUNDAY-MONDAY...VFR. E WINDS G20KT POSSIBLE IN THE AFTERNOON ON MONDAY. .TUE...VFR. && .MARINE... DEPARTING HIGH PRESSURE WILL KEEP SUB-SCA CONDITIONS IN PLACE THROUGH FRI NIGHT. OCNL GUSTS TO 25 KT ARE POSSIBLE ON SAT AS THE PRES GRADIENT TIGHTENS WITH THE APPROACH AND PASSAGE OF A COLD FRONT. HIGH PRES THEN BUILDS OVER THE WATERS FOR THE START OF THE NEW WEEK. A PERSISTENT EASTERLY FLOW WILL DEVELOP ON THE WATERS...POSSIBLY PUSHING OCEAN SEAS CLOSE TO SCA LEVELS BY THE MIDDLE OF THE NEW WORK WEEK. && .HYDROLOGY... SHOWERS AND THUNDERSTORMS ARE LIKELY SAT INTO SAT NIGHT. STRONGER STORMS COULD PRODUCE HEAVY RAIN AND LOCALIZED FLOODING OF URBAN/POOR DRAINAGE AREAS AND SMALL STREAMS. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...GOODMAN/MPS NEAR TERM...GOODMAN/MPS SHORT TERM...GOODMAN LONG TERM...MPS AVIATION...JP MARINE...GOODMAN/MPS HYDROLOGY...MPS
AREA FORECAST DISCUSSION
NWS NEW YORK NY
238 PM EDT THU SEP 4 2014 .SYNOPSIS... HIGH PRESSURE OVER THE AREA THROUGH TONIGHT WILL SHIFT OFFSHORE FRIDAY INTO FRIDAY NIGHT AS A COLD FRONT APPROACHES FROM THE WEST. THE COLD FRONT WILL MOVE ACROSS THE AREA FROM SATURDAY AND SATURDAY NIGHT. HIGH PRESSURE WILL THEN BUILD IN FROM SUNDAY INTO THE MIDDLE OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... SCT CU OVER INTERIOR SECTIONS NORTH/WEST OF NYC AND ALONG THE SEA BREEZE FRONT ON LONG ISLAND SHOULD DISSIPATE TONIGHT...LEAVING MAINLY CLEAR SKIES. BOTH THE 12Z NAM AND 17Z RAP ARE SHOWING LOW STRATUS AND/OR FOG DEVELOPMENT TOWARD DAYBREAK CLOSE TO LONG ISLAND VIA INCREASED LOW LEVEL MOISTURE IN ONSHORE FLOW AND COOLING BENEATH A SFC-BASED INVERSION. ATTM SUSPECT NAM LOW LEVEL MOISTURE IS OVERDONE...SO HAVE SIDED MORE WITH THE RAP WITH AT LEAST PTCLDY SKIES THERE LATE. EXPECT LOWS IN THE UPPER 50S IN THE LONG ISLAND PINE BARRENS AND SOME INTERIOR VALLEYS...60S MOST ELSEWHERE...AND LOWER 70S IN NYC. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... EXPECT MAINLY DRY WX AS THE HIGH SHIFTS OFFSHORE. PRESENCE OF A WEAK SFC TROUGH IN THE WAKE OF THE DEPARTING HIGH...WEAK LOW LEVEL WAA...AND APPROACH OF MID LEVEL SHORTWAVES FROM THE WEST AND SOUTHWEST MAY SPARK ISOLD SHOWERS LATE FRI NIGHT. WITH CONTINUED ONSHORE FLOW THERE SHOULD BE A BETTER CHANCE FOR LOW CLOUDS AND FOG TO DEVELOP LATE AT NIGHT. TEMPS ON FRI WITH ONSHORE FLOW AND MORE IN THE WAY OF CLOUDS SHOULD BE CLOSE TO OR ONLY SLIGHTLY LOWER THAN THOSE OF TODAY...WITH UPPER 70S FOR COASTAL SE CT AND 80S ELSEWHERE. LOWS FRI NIGHT SHOULD BE IN THE MID/UPPER 60S INLAND...AND LOWER 70S IN NYC METRO AND LONG ISLAND. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... POPS INCREASE RATHER QUICKLY DURING THE DAY SATURDAY AS THE COLD FRONT MOVES INTO THE REGION. MODELS ARE IN GENERAL AGREEMENT ON THE TIMING OF THE SURFACE FEATURES...WITH THE 00Z GFS CONTINUING TO BE A LITTLE ON THE QUICK SIDE. EVEN THOUGH THE GFS IS A LITTLE QUICKER THAN THE OTHER 00Z MODELS...THEY ALL HAVE THE PRECIPITATION ENDING EARLY SUNDAY MORNING. WILL CONTINUE TO KEEP LIKELY POPS IN FOR SATURDAY AND SATURDAY NIGHT ACROSS THE AREA. ALSO...WITH INSTABILITY ACROSS THE REGION...EXPECT THUNDER TO ALSO BE LIKELY WITH THE FRONT. GUSTY WINDS AND HEAVY RAIN WILL BE POSSIBLE WITH ANY STRONGER STORMS. THE FRONT MOVES EAST OF THE REGION SUNDAY MORNING WITH HIGH PRESSURE BUILDING INTO THE REGION...ALLOWING CONDITIONS TO DRY OUT. NORTHERLY FLOW WILL BECOME MORE NE/E DURING THE FIRST HALF OF THE WEEK...WITH CONDITIONS FAIRLY COOLER THAN THIS WEEK. MOST AREAS WILL BE AT OR BELOW NORMAL...GENERALLY IN THE 70S. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... HIGH PRESSURE OVER THE AREA THIS MORNING...SLIDES OFFSHORE INTO TONIGHT. VFR THROUGH THE TAF PERIOD AT AREA TERMINALS. SEA BREEZE HAS ALREADY MOVED THROUGH CITY TERMINALS AND WILL AFFECT ALL BUT KSWF TODAY WHERE A LIGHT SW FLOW HAS DEVELOPED. FLOW BECOMES LIGHT OUT OF THE SSW-SW THROUGHOUT BY EARLY EVENING...THEN LIGHT AND VARIABLE THROUGHOUT BY AROUND MIDNIGHT TONIGHT. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. KLGA FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. KEWR FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. LOW CHANCE OF TEMPO BR LIMITING VIS TO 6SM BETWEEN 10Z AND 13Z. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. LOW CHANCE OF TEMPO BR LIMITING VIS TO 6SM BETWEEN 10Z AND 13Z. KHPN FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. TEMPO BR LIMITING VIS TO 5SM OR LOWER BETWEEN 09Z AND 13Z. KISP FCSTER COMMENTS: WIND DIRECTION WITH SEA BREEZE COULD VARY +/- 20 TO 30 DEGREES. .OUTLOOK FOR 12Z FRIDAY THROUGH MONDAY... .FRIDAY...MAINLY VFR. MVFR FOG POSSIBLE INLAND TERMINALS EARLY. ISOLD SHRA/TSTM POSSIBLE N/W OF CITY TERMINALS. .FRIDAY NIGHT...MVFR OR LOWER POSSIBLE IN ANY LOW CLOUDS AND/OR FOG. SLIGHT CHANCE SHRA/TSTM W OF CITY TERMINALS. .SATURDAY TO SATURDAY NIGHT...MVFR OR LOWER POSSIBLE IN SCT- NUMEROUS SHRA/TSTMS. LOW CLOUDS AND/OR FOG POSSIBLE EARLY IN THE MORNING. SW-W WINDS G20+ KT POSSIBLE SATURDAY...SHIFTING TO THE NW-N SATURDAY NIGHT. .SUNDAY-MONDAY...VFR. E WINDS G20KT POSSIBLE IN THE AFTERNOON ON MONDAY. .TUE...VFR. && .MARINE... DEPARTING HIGH PRESSURE KEEP SUB-SCA CONDITIONS IN PLACE THROUGH FRIDAY NIGHT. WINDS AND SEAS WILL INCREASE WITH SW FLOW SATURDAY AHEAD OF AN APPROACHING COLD FRONT. HOWEVER...THEY LOOK TO REMAIN BELOW SCA CRITERIA AT THIS TIME. THE FRONT PASSES ACROSS THE WATERS SATURDAY NIGHT...WITH SHOWERS AND THUNDERSTORMS FORECAST. NORTHERLY FLOW THEN TAKES OVER SUNDAY INTO MONDAY...WITH CONDITIONS REMAINING BELOW SCA CRITERIA. && .HYDROLOGY... NO SIGNIFICANT HYDROLOGIC ISSUES ARE EXPECTED THROUGH FRIDAY NIGHT. SHOWERS AND THUNDERSTORMS ARE FORECAST SATURDAY INTO SATURDAY NIGHT. WHILE WIDESPREAD HEAVY RAIN IS NOT ANTICIPATED...ANY STRONGER STORM WILL BE CAPABLE OF PRODUCING BRIEF HEAVY RAINFALL RATES. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...BC/SEARS NEAR TERM...GOODMAN SHORT TERM...SEARS LONG TERM...BC AVIATION...JP MARINE...GOODMAN HYDROLOGY...BC/SEARS
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
855 PM EDT FRI SEP 5 2014 ...LOCALLY HEAVY RAINFALL THREAT WILL CONTINUE THROUGH THE WEEKEND... .UPDATE... LATEST RUC13 SFC-700 MB STREAMLINE ANALYSIS SHOW LOW PRESSURE SPINNING IN THE LOWER LEVELS OF THE ATMOSPHERE JUST WEST OF JACKSONVILLE AND MODELS ALL IN AGREEMENT WITH DRIFTING THIS FEATURE VERY SLOWLY TO THE N/NE INTO SE GA TOWARDS MORNING THEN N/NE TO JUST WEST OF SAVANNAH BY LATE SATURDAY. VERY MOIST TROPICAL AIRMASS WITH PRECIPITABLE WATER AMOUNTS GREATER THAN 2 INCHES WILL KEEP A CHANCE OF SHOWERS OVER LAND AREAS THROUGH THE NIGHT WITH NUMEROUS SHOWERS AND EMBEDDED STORMS OVER THE COASTAL WATERS. RAIN COOLED TEMPS ARE ALREADY IN THE 70S THIS EVENING AND WILL REMAIN STEADY THROUGH THE NIGHT. DAYTIME HEATING COMBINED WITH TROPICAL AIRMASS IN PLACE ON SATURDAY WILL TRIGGER NUMEROUS SHOWERS AND STORMS BY THE AFTERNOON WITH LOCALLY HEAVY RAINFALL AND FREQUENT LIGHTNING REMAINING THE MAIN THREATS. SLOW STORM MOTION TOWARDS THE EAST WILL ALLOW STORMS TO INTERACT WITH ATLC COAST SEA BREEZE ALONG THE I-95 CORRIDOR AND HEAVY RAINFALL THREAT THERE IS THE HIGHEST ALTHOUGH LOCALIZED HEAVY STORMS POSSIBLE AREA-WIDE ACROSS SE GA/NE FL. MAX TEMPS WILL GENERALLY ONLY REACH INTO THE 85-90 RANGE BEFORE SHOWER/STORM ACTIVITY IS TRIGGERED. STILL TOO EARLY TO DETERMINE THE NEED FOR ANY FLASH FLOOD WATCH AS HEAVY RAINFALL WAS STILL TOO LOCALIZED TODAY TO POINT TO ANY ONE REGION FOR A WATCH. && .AVIATION... VFR CONDITIONS ARE EXPECTED TO PREVAIL OVERNIGHT WITH CEILINGS PRIMARILY ABOVE 5K FEET. THE HRRR DOES INDICATE SOME LOW CEILINGS ACROSS PORTIONS OF THE AREA OVERNIGHT BUT THE NARRE DOES NOT SUPPORT THIS. DUE TO THE UNCERTAINTY WE DID NOT HAVE ENOUGH CONFIDENCE TO INCLUDE THIS IN THE 0Z TAF PACKAGE. ANOTHER ROUND OF NUMEROUS THUNDERSTORMS ARE EXPECTED SATURDAY AFTERNOON AND FOR NOW WE WILL GO AHEAD AND CARRY VCTS AT ALL TAF SITES. && .MARINE... WITH LOW JUST INLAND OVER SE GA OVERNIGHT EXPECT S/SW FLOW OVER THE COASTAL WATERS GENERALLY AT 10-15 KNOTS WITH SEAS 2-4 FT AND THIS WILL CONTINUE INTO SATURDAY. MAIN IMPACTS WILL BE NUMEROUS SHOWERS AND EMBEDDED STORMS WITH GUSTY WINDS/LIGHTING AND HEAVY RAINFALL. RIP CURRENTS: LOW RISK IN THE GENERAL S/SW FLOW. && .PRELIMINARY POINT TEMPS/POPS... AMG 71 89 73 90 / 50 70 60 70 SSI 75 84 75 86 / 70 60 60 60 JAX 72 88 73 89 / 70 60 60 60 SGJ 74 86 74 86 / 70 50 50 60 GNV 70 87 72 87 / 60 60 60 60 OCF 70 86 72 86 / 60 60 50 60 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ HESS/SHULER/GUILLET
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
334 AM EDT THU SEP 4 2014 .DISCUSSION... TODAY-TONIGHT...AXIS OF THE EASTERLY WAVE IS CURRENTLY MOVING THROUGH THE FLORIDA PENINSULA EARLY THIS MORNING...WITH RUC ANALYSIS SHOWING THE MAIN VORT MAX ASSOCIATED WITH THE FEATURE STILL BACK OVER THE NW BAHAMAS. THIS IS COINCIDENT WITH THE LARGER AREA OF SHOWERS AND STORMS PRESENT OVER THE ATLANTIC EARLY THIS MORNING...WITH A SLOW INCREASE IN ACTIVITY OVER THE LOCAL WATERS AS THIS FEATURE ROTATES FURTHER NORTH AND WEST. WAVE WILL SLOWLY TRANSIT THE PENINSULA DURING THE DAY...PUTTING THE REGION ON THE MORE FAVORED ASCENDING SIDE OF THE WAVE. SOUTH-SOUTHEAST FLOW WILL PUSH THE CURRENT DRY SLOT FURTHER NORTH AND ALLOW MUCH DEEPER MOISTURE TO OVERSPREAD THE AREA. THOUGH MODELS SHOW BEST DYNAMICS (COOLER TEMPS ALOFT AT VORT MAX) STAYING MORE OVER THE ATLANTIC...ENOUGH WILL BE IN PLACE FOR POPS IN THE 50-60 PERCENT RANGE OVER THE REGION THIS AFTERNOON. THERE WILL PROBABLY BE AN INITIAL FOCUS ALONG THE TREASURE COAST AS ONGOING ACTIVITY OVER THE ATLANTIC ROTATES CLOSER TO THE PENINSULA...THEN SHOWERS AND STORMS WILL SHIFT INLAND WITH EAST COAST SEA BREEZE. MORE SOUTHERLY COMPONENT TO THE FLOW WILL ALLOW BETTER WEST COAST SEA BREEZE PENETRATION AND MODELS SHOW EVENING COLLISION AROUND LAKE COUNTY BEFORE SUNSET. A FEW SHOWERS AND STORMS LINGER INTO EARLY EVENING BEFORE FOCUS SHIFTS BACK TO ATLANTIC WITH A FEW SHOWERS AND STORMS BRUSHING THE COAST OVERNIGHT. FRIDAY...A MID LVL TROUGH WILL MOVE FROM THE CENTRAL FL PENINSULA TOWARD THE NRN FL PENINSULA THROUGH THE DAY WITH LOW LVL SE FLOW ACROSS THE AREA. AN AREA OF DEEP MOISTURE CENTERED OVER ORLANDO COMBINED WITH MID LVL PVA ALONG AND SOUTH OF THE SHEAR AXIS SHOULD GENERATE SCATTERED TO NUMEROUS SHOWERS AND LIGHTNING STORMS ACROSS THE INTERIOR WITH 40-50 RAIN CHANCES NEAR THE EAST COAST. WITH CONSIDERABLE CLOUD COVER IN THE MORNING AND DECENT COVERAGE OF AFTERNOON SHOWERS AND STORMS HAVE TRIMMED GFS MOS HIGH TEMPS A FEW DEGREES...INTO THE LOWER 90S INTERIOR TO AROUND 90 AT THE COAST. COULD BE A FEW STRONG STORMS NEAR METRO ORLANDO AND LAKE COUNTY IN THE LATE AFTERNOON WITH LOCALLY HEAVY...GUSTY WINDS AND FREQUENT LIGHTING. FRIDAY NIGHT...A CHANCE OF STORMS WILL LINGER DURING THE EVENING ACROSS MAINLY NORTHERN SECTIONS WITH A CHANCE FOR SHOWERS CONTINUING PAST LATE EVENING. KEPT POPS CLOSE TO MOS WITH LOW TEMPS IN THE LOWER TO MID 70S. SATURDAY...A CLOSED 700 MB LOW ACROSS SE GA SHOULD INDUCE LOW PRESSURE TO DEVELOP TO OUR NORTH ACROSS GA/SC. DEEP MOISTURE WILL CONTINUE TO TRAIL INTO OUR NRN FORECAST AREA FROM THIS FEATURE WITH SE/S LOW LVL WINDS AND SW FLOW AT H7. WILL KEEP HIGHEST RAIN CHANCES FROM 50-60 PCT ACROSS THE INTERIOR AND SLIGHTLY LOWER ALONG THE COAST WHERE THE EAST COAST SEA BREEZE SHOULD PUSH SLOWLY INLAND WITH BETTER INLAND PROGRESS ACROSS THE TREASURE COAST. HIGHS UPPER 80S TO AROUND 90 AT THE COAST AND LOWER 90S OVER THE INTERIOR. SAT NIGHT/SUNDAY...MID LVL TROUGH CONTINUES ALONG THE SE ATLC COAST INTO CENTRAL FL WITH GFS INDICATING DEEP MOISTURE LINGERING. THIS SHOULD ALLOW THE CHANCE FOR STORMS TO CONTINUE INTO SAT EVENING AND REDEVELOP ON SUNDAY WITH DAYTIME HEATING. WILL SHOW POPS AROUND 50 PCT FOR THE INTERIOR/N COAST AND 40 PCT FROM THE CAPE SOUTH ALONG THE COAST WHERE THE EAST COAST SEA BREEZE SHOULD PUSH INTO THE INTERIOR IN THE AFTERNOON. NO RELIEF FROM THE HEAT WITH 90 ALONG THE COAST AND LOWER 90S FOR THE INTERIOR. MON-WED...THE TROUGH NEAR THE SE ATLC COAST WILL TRANSITION OFFSHORE WITH A MORE ZONAL FLOW SETTING UP BY MID WEEK ACROSS THE SOUTH AND THE MID LVL RIDGE REBUILDING ACROSS CENTRAL FL BY WED. APPEARS THERE WILL CONTINUE TO BE ADEQUATE MOISTURE FOR SLIGHTLY HIGHER THAN NORMAL RAIN CHANCES MONDAY...AND THEN WILL TAPER POPS INTO MID WEEK WITH HIGHER CHANCES ACROSS THE INTERIOR TUE/WED AROUND 40 PCT. HIGHS 90 COAST TO LOWER-MID 90S FOR THE INTERIOR INTO MID WEEK. && .AVIATION... SCT SHRA/TSRA OVER LCL ATLANTIC THROUGH PERIOD. ISOLD SHRA BRUSHING ALL COASTAL TERMINALS THROUGH 10Z...EXPECTED TO BECOME SCT-NMRS WITH ISOLD TSRA 12Z-15Z. FOCUS FOR CONVECTION WILL SHIFT TO INTERIOR AFTER 15Z WITH SCT-NMRS SHRA/TSRA AFFECTING INLAND TERMINALS THROUGH 21Z. EVENING SEA BREEZE COLLISION LIKELY VCNTY KLEE/KISM WHERE ACTIVITY MAY LINGER THROUGH 05/02Z. && .MARINE... TODAY-TONIGHT...SOUTH-SOUTHEAST FLOW 10-15KTS AS LOCAL ATLANTIC WILL BE IN BETWEEN EASTERLY WAVE MOVING ACROSS S FL/FL STRAITS AND WESTERN ATLANTIC RIDGE AXIS OVER THE SE US. PREVAILING SPEEDS MAY BE CLOSER TO 10KTS DURING THE DAY...BUT WILL SEE AN INCREASE LATER THIS EVENING AS AREA GETS ON THE BACKSIDE OF WAVE. SEAS 2FT NEARSHORE AND 2-3FT OFFSHORE. MESSY DOMINANT PERIODS AS THERE IS ENOUGH OF A SOUTHERLY FLOW COMPONENT THAT QUITE A BIT OF THE LOCAL WATERS ARE BEING SHADOWED BY THE BAHAMAS. LOCAL BUOYS ARE CURRENTLY FAVORING 3-5SEC WITH OCCASIONAL 7-8SEC...AND WAVE WATCH AND SWAN SHOW SIMILAR TREND INTO TONIGHT. NUMEROUS SHOWERS AND SCATTERED STORMS OVER THE LOCAL WATERS TODAY...BECOMING SCT INTO TONIGHT. FRI-MON...SE-S WINDS UP TO 10-15 KNOTS OFFSHORE OVER THE WEEKEND AND INTO EARLY NEXT WEEK...ESPECIALLY AT NIGHT WHEN A NOCTURNAL INCREASE IN WINDS IS EXPECTED MOST NIGHT PERIODS THROUGH THE WEEKEND. SEAS WILL REMAIN 2 FT NEAR SHORE AND 2-3 FT OFFSHORE. HIGHER COVERAGE OF SHOWERS AND STORMS FRIDAY INTO SATURDAY AND THEN DECREASING ACROSS THE WATERS SUNDAY INTO EARLY NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... DAB 91 75 90 76 / 50 40 50 30 MCO 93 75 92 74 / 50 30 60 30 MLB 90 76 89 76 / 60 40 50 30 VRB 90 74 90 76 / 60 40 50 20 LEE 92 75 92 77 / 60 30 60 30 SFB 93 76 92 77 / 50 30 60 30 ORL 93 77 92 77 / 50 30 60 30 FPR 88 75 90 75 / 60 30 40 20 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM/AVIATION...MOSES LONG TERM....VOLKMER
AREA FORECAST DISCUSSION
NWS POCATELLO ID
810 PM MDT FRI SEP 5 2014 .DISCUSSION...A QUICK UPDATE THIS EVENING TO EXPIRE THE LAKE WIND ADVISORY ACROSS AMERICAN FALLS. 18Z NAM AND RECENT HRRR MODEL RUNS SHOW A WEAKER NE FLOW SATURDAY MORNING...SUB-ADVISORY. THE LOCAL 18Z WRF HOWEVER WAS SHOWING SOME FAIRLY STIFF NE WINDS THROUGH THE MORNING BEFORE THE SW WINDS ALOFT MIX DOWN INTO THE BOUNDARY LAYER. WOULD LIKE TO SEE THE 00Z PACKAGE BEFORE PULLING THE TRIGGER ON A MARGINAL ADVISORY. WILL ADVISE MID-SHIFT. SEE PREVIOUS DISCUSSION BELOW. HUSTON A MINOR UPPER WAVE MOVING OVER THE SW US RIDGE IS SETTING OFF A FEW SHOWERS/ISOLD TSTMS OVER UT THIS AFTN WHICH MAY SPREAD INTO THE SE CORNER OF ID LATER THIS AFTN AND EVE. AS THE RIDGE BUILDS BACK UP...SOME TROPICAL MOISTURE IS EXPECTED TO FLOW NORTH. THIS WILL RESULT IN WIDELY SCT SHOWERS/TSTMS MAINLY OVER THE SE HIGHLANDS THRU MONDAY. BY TUE...THE NORTHERN BRANCH OF THE UPPER JET BEGINS TO SAG SOUTHWARD INTO NRN ID AND MT. THIS WILL BRING A BACK DOOR COLD FRONT FROM WY...THRU ID...INTO WA. THIS INCREASES THE CHANCES FOR SHOWERS/TSTMS OVER THE MTNS ON TUE. BY WED ALL THE MOISTURE IS PUSHED OUT OF THE AREA...LEAVING COOLER AND DRY CONDITIONS FOR THE REST OF THE WEEK. HEDGES && .AVIATION...NORTH WIND WILL BE LIGHTER...AND SHOULD DISAPPEAR FOR SAT AFTERNOON. OTHERWISE A POTENTIAL MID-LEVEL CIG AT KBYI WITH APPROACH OF SOME WEAK MOISTURE FROM THE SOUTH...BUT ONLY FOR A FEW HOURS. EXTREMELY DRY AIR IN THE NORTHERLY AIR FLOW. MESSICK && .FIRE WEATHER...HIGH PRESSURE WITH A CESSATION OF THE COOLING NORTHERLY WIND WILL ALLOW TEMPERATURES TO JUMP STRONGLY AND AFTERNOON HUMIDITY TO DRY SOMEWHAT OVER THE WEEKEND PERIOD. THE SWITCH TO SOUTHERLY WIND WILL ALLOW MORE AREAS OF THUNDERSTORM ACTIVITY IN THE CARIBOU PORTION OF THE CARIBOU-TARGHEE NF...BUT STILL ISOLATED IN COVERAGE. THIS WILL CONTINUE EACH AFTERNOON AND EVENING UNTIL A TROUGH MOVES THROUGH FROM THE WEST. THIS WILL BRING SOME WIND...SHOWERS AND THUNDERSTORMS TO THE MOUNTAINS OF THE FORECAST AREA. IT COULD BE GREATER COVERAGE IF THE FRONT IS ABLE TO TAP INTO MOISTURE FROM HURRICANE NORBERT...WHICH COULD BE OVER THE SOUTHERN CALIFORNIA COAST AND THUS COULD PUMP QUITE A BIT OF MOISTURE INTO THIS FRONT. RIGHT NOW...IT DOES NOT LOOK VERY FAVORABLE...BUT WILL REQUIRE MONITORING. MESSICK && .PIH WATCHES/WARNINGS/ADVISORIES...NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1257 PM CDT THU SEP 4 2014 .DISCUSSION... 1240 PM CDT PERSISTENT CONVECTION IS FINALLY STARTING TO WANE EARLY THIS AFTERNOON BUT SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL LINGER FOR ANOTHER HOUR OR SO. EXCEPT IN AREAS GETTING MORE SUN THAN RAIN SO FAR TODAY...HIGHS ARE ONCE AGAIN THIS YEAR GOING TO HAVE TROUBLE GETTING QUITE UP TO INITIAL EXPECTATIONS...BUT A WARM AND HUMID AFTERNOON IS STILL LIKELY WITH DEWPOINTS IN THE 70S AND TEMPERATURES RECOVERING INTO THE 80S. FORECAST GRIDS ARE ADJUSTED ACCORDINGLY AND AN UPDATED SET OF ZONES WAS SENT EARLIER THIS HOUR. LENNING && .PREVIOUS DISCUSSION... 327 AM CDT MORNING THUNDERSTORM COVERAGE AND DURATION ALONG WITH IMPACT ON DAYTIME TEMPERATURES ARE THE SHORT TERM CHALLENGES. THUNDER CHANCES AND DEGREE OF COOL DOWN ARE THE MAIN LONG TERM POINTS OF EMPHASIS TODAY. SHORT TERM...TODAY AND TONIGHT... AN ACTIVE ELEVATED WARM AND MOIST ADVECTION ZONE SUPPORTING AREAS OF CONVECTION IS OVER THE REGION EARLY THIS MORNING. A SHORT WAVE DISTURBANCE IN EASTERN IA AS OF 330 AM HAS BEEN AN INSTIGATOR FOR MORE ORGANIZED CONVECTION OVER THE DVN CWA. A BROAD BUT STRONG 45KT LOW-LEVEL JET IS ADVECTING IN MOIST AIR AT THE BASE OF STEEPENING MID-LEVEL LAPSE RATES OF 7-8 C/KM. THIS WILL REMAIN SUPPORTIVE OF WIDESPREAD CONVECTIVE UPDRAFTS THROUGH 8-9 AM BEFORE A PROBABLE DIMINISHING TREND AS STORMS APPROACH/MOVE OVER CHICAGO AND THE I-55 CORRIDOR. A RAP ANALYSIS INDICATES FAIRLY SHORT CORFIDI PROPAGATION VECTORS WITH NORTHWEST MID-LEVEL FLOW PERPENDICULAR TO THE LLJ. SO ISOLATED HEAVY RAIN CONCERNS WILL BE PRESENT AND HAVE BEEN SUPPORTED ON REGIONAL RADAR TRENDS. HAVE INCREASED QPF IN TANDEM WITH HIGHER POPS THROUGH MID-MORNING. A STRENGTHENING CAP ALONG WITH THE WEAKENING/EXIT OF THE AFOREMENTIONED SHORT WAVE SHOULD LIMIT ANY CONVECTIVE CHANCES THIS AFTERNOON. HOWEVER...SOME CLOUDS MAY LINGER INTO EARLY AFTERNOON. WITH THAT AND SOME COMMUNITIES SEEING A SLOWER WARMING TREND EARLY THIS MORNING WITH CLOUDS AND RAIN...HAVE LOWERED TEMPERATURES IN THE NORTHEAST HALF OF THE FORECAST AREA BY A COUPLE DEGREES. TEMPERATURES SHOULD STILL REALIZE 90 IN FAR WESTERN/SOUTHWESTERN AREAS BASED ON 850/925MB TEMPERATURE CLIMATOLOGY AND SUPPORT FROM PAST SIMILAR EVENTS PER THE CIPS ANALOGS. HEAT INDEX READINGS IN THIS AREA...FROM BYRON TO GIBSON CITY AND WESTWARD...WILL LIKELY APPROACH 100 DEGREES DUE TO FORECAST LOWER 70 DEW POINTS. A QUIET AND MILD EVENING IS EXPECTED. CONFIDENCE FOR PRECIP REMAINING OUT OF THE AREA OVERNIGHT IS LOW. WHILE FRONTAL CONVERGENCE REMAINS OFF TO THE NORTHWEST...QUITE A BIT OF ELEVATED INSTABILITY WILL BE PRESENT AND OVERALL FORCING FOR PRECIP IS LOW. BUT AS WE HAVE SEEN EARLY THIS MORNING...EVEN A SUBTLE WAVE CAN CAUSE PROBLEMS. SO CONTINUE CHANCE POPS. MTF LONG TERM FRIDAY THROUGH WEDNESDAY... THE MAIN FORECAST CONCERNS DURING THE LONG TERM PERIOD FOCUS ON THE THREAT FOR SHOWERS AND THUNDERSTORMS...SOME POSSIBLY STRONG...AND THE THREAT OF HEAVY RAINFALL FRIDAY AND FRIDAY NIGHT. SURFACE LOW PRESSURE CURRENTLY ACROSS THE EASTERN DAKOTAS WILL SHIFT NORTHEASTWARD TO NEAR JAMES BAY BY THE START OF THE PERIOD (FRIDAY MORNING). THIS LOW WILL DRIVE A COLD FRONT SOUTHWARD OVER NORTHERN ILLINOIS BY EARLY FRIDAY AFTERNOON. THE TIMING OF THIS FRONTAL PASSAGE SHOULD ALLOW THE HEAT AND HUMIDITY TO LINGER...AT LEAST FOR THE FIRST HALF OF THE DAY...ESPECIALLY ACROSS MY SOUTHERN AREAS. THEREFORE...HIGHS ON FRIDAY LOOK TO ONCE AGAIN CREEP NEAR THE 90 DEGREE MARK...WITH HEAT INDICIES OF 95 TO 100 SOUTH OF INTERSTATE 80. THUNDERSTORMS WILL LIKELY FIRE ACROSS FAR NORTHERN ILLINOIS EARLY ON FRIDAY AS THE FRONT APPROACHES...AND LIKELY INCREASE IN AREAL COVERAGE BY FRIDAY AFTERNOON. SURFACE BASED STORMS APPEAR LIKELY...AHEAD OF THE FRONTAL BOUNDARY LATER FRIDAY MORNING AND INTO THE AFTERNOON...WITH THE PREFRONTAL HIGH THETA-E LOWER LEVEL AIR MASS EXPECTED TO INDUCE MLCAPES OF 2000-3000 J/KG. ALTHOUGH DEEP LAYER SHEAR WILL BE SOMEWHAT LACKLUSTER...WITH ONLY AROUND 25 KT OF 0-6 KM BULK SHEAR...THERE WILL BE A SMALL THREAT FOR MULTI-CELL CLUSTERS CAPABLE OF PRODUCE STRONG WINDS. HOWEVER...IT APPEAR THE MAIN THREAT FOR THIS MAY REMAIN SOUTH OF THE CHICAGO AND ROCKFORD AREAS. THE OTHER THREAT WITH THESE STORMS...AS HAS BEEN THE CASE WITH STORMS FOR THE LAST FEW WEEKS...IS VERY HEAVY RAINFALL. THE HIGH THETA E AIR MASS FEATURING PWAT VALUES OF 1.8 TO 2 INCHES WILL LEAD TO VERY EFFICIENT RAINFALL RATES...AND THIS COUPLED WITH THE FACT THAT THE STEERING LAYER FLOW LOOKS TO RUN NEARLY PARALLEL TO THE SURFACE FRONTAL ZONE...TRAINING CELLS ARE A GOOD POSSIBILITY. IT ALSO APPEARS THAT SHOWERS...POSSIBLY WITH SOME EMBEDDED ELEVATED THUNDERSTORMS...WILL LIKELY CONTINUE IN THE WAKE OF THE SURFACE BOUNDARY INTO FRIDAY NIGHT AS AN ANA-LIKE FRONTAL PRECIP EVENT SETS UP. MID LEVEL FGEN AND THE PROXIMATELY TO THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET ALL POINT TO CONTINUED FORCING TO SUPPORT PRECIP INTO FRIDAY NIGHT. GIVEN THE POSSIBILITIES OF A PERIOD OF VERY HEAVY RAINFALL...WITH POSSIBLE TRAINING OF CELLS AHEAD OF THE FRONT...FOLLOWED BY A LONGER PERIOD OF MODERATE PRECIP INTO FRIDAY NIGHT...HYDRO ISSUES COULD BECOME A CONCERN. THINGS QUIET DOWN AND BECOME MUCH COOLER FOR THE WEEKEND UNDER NORTHERN FLOW. HIGH TEMPERATURES BY SATURDAY AND SUNDAY LOOK TO BE IN THE LOW TO MID 70S. OVERNIGHT TEMPERATURES INTO SUNDAY MORNING LOOKS TO BE QUITE CHILLY AS A SURFACE HIGH BUILDS OVERHEAD. THIS LOOKS TO SET UP WIDESPREAD LOWER 50 DEGREE TEMPERATURES OUTSIDE OF CHICAGO...WITH EVEN A FEW UPPER 40 DEGREE READINGS POSSIBLE IN THE WESTERN SUBURBS. TEMPERATURES LOOK TO MODERATE A BIT BACK INTO THE UPPER 70S INTO NEXT WEEK. THE NEXT CHANCE FOR STORMS LOOKS TO ENTER THE PICTURE AGAIN BY LATE MONDAY NIGHT AND TUESDAY AS ANOTHER DISTURBANCE TAKES AIM ON THE AREA. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 18Z... * SHRA/TSRA TRENDS...OVERALL DECREASING RAPIDLY. * WIND SPEEDS AND DIRECTIONS NEAR LINGERING TSRA. * MORE TSRA POSSIBLE TOMORROW. LENNING //DISCUSSION...UPDATED 18Z... TSRA HAS MOSTLY MOVED SOUTH OF THE TERMINALS AS ANTICIPATED BUT A FEW LINGERING SHOWERS AND ISOLATED STORMS REMAIN IN THE AREA. COVERAGE HAS BEEN DECREASING RAPIDLY HOWEVER SO ONLY CARRIED AN HOUR OR SO IN THE START OF THE TAFS. WINDS OVERALL REMAIN SOUTHERLY BUT SOME LOCATIONS ARE SEEING BRIEF STRONG GUSTS AND SHARP DIRECTIONAL CHANGES. OPTED TO GO WITH THE PREVAILING TREND IN THE TAF RATHER THAN CHASE TRANSIENT AND UNPREDICTABLE LOCAL EFFECTS. AFTER A BRIEF PERIOD OF BACKING THIS AFTERNOON...VERY GRADUAL VEERING IN THE WINDS SHOULD BE THE TREND THROUGH THE EVENING INTO TOMORROW AHEAD OF AN APPROACHING COLD FRONT. MODELS HAVE THIS FRONT REACHING THE LOCAL AREA TOWARD MID DAY TOMORROW...SO HAVE TIMED PRECIP CHANCES TO MATCH THE ARRIVAL OF CONVERGENCE EFFECTS ALONG THIS BOUNDARY. LENNING //ORD AND MDW CONFIDENCE...UPDATED 18Z... * MEDIUM TO HIGH CONFIDENCE IN ALL ELEMENTS EXCEPT FOR PRECIP TIMING TOMORROW. LENNING //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...CHANCE OF SHRA AND SLIGHT CHANCE OF TSRA. SATURDAY...VFR. NORTHEAST WINDS. SUNDAY-MONDAY...VFR. TUESDAY-WEDNESDAY...CHANCE OF TSRA. MTF && .MARINE... 155 AM CDT THE WEATHER PATTERN ACROSS THE GREAT LAKES REGION WILL BE A BIT ACTIVE OVER THE NEXT FEW DAYS...WITH SOME PERIODS OF STRONG WINDS IN THE 25 TO 30 KT RANG...ALONG WITH A PERIOD OR TWO OF SHOWERS AND STORMS. A RATHER POTENT EARLY AUTUMN SEASON SURFACE LOW WILL MOVE FROM THE EASTERN DAKOTAS EARLY THIS MORNING TO NEAR JAMES BAY BY EARLY FRIDAY MORNING. THIS SYSTEM WILL CONTINUE TO INDUCE SOME STRONG SOUTHERN WINDS OVER THE LAKE TODAY AND TONIGHT. IT APPEARS THE STRONGEST WINDS UP TO AROUND 30 KT WILL OCCUR THIS EVENING ACROSS THE NORTHERN HALF OF THE LAKE...WITH 20 TO 25 KT SOUTHERLY WINDS OVER THE SOUTHERN HALF OF THE LAKE. THESE STRONG WINDS WILL RESULT IN SMALL CRAFT ADVISORY CONDITIONS INTO THIS EVENING. AS THE LOW SHIFTS OVER THE JAMES BAY FRIDAY MORNING...A TRAILING COLD FRONT WILL SHIFT DOWN THE LAKE DURING THE DAY FRIDAY. WINDS WILL SHIFT NORTHERLY INTO 15 TO 25 KT RANGE LATER FRIDAY AND INTO SATURDAY...BEFORE ABATING LATER SATURDAY AS AN AREA OF SURFACE HIGH PRESSURE BUILDS ACROSS THE SOUTHERN LAKES REGION. THESE NORTHERLY WINDS DOWN THE FETCH OF LAKE MICHIGAN MAY AGAIN RESULT IN SMALL CRAFT ADVISORY CONDITIONS FRIDAY NIGHT AND SATURDAY...WITH WAVES POSSIBLY IN THE 4 TO 7 FT RANGE. THE WEATHER CONDITIONS LOOK TO QUIET DOWN FOR A COUPLE DAYS FOR SUNDAY AND INTO EARLY NEXT WEEK AS SURFACE HIGH PRESSURE DOMINATES ACROSS THE LAKES REGION. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 10 PM THURSDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1121 AM CDT THU SEP 4 2014 .DISCUSSION... 327 AM CDT MORNING THUNDERSTORM COVERAGE AND DURATION ALONG WITH IMPACT ON DAYTIME TEMPERATURES ARE THE SHORT TERM CHALLENGES. THUNDER CHANCES AND DEGREE OF COOL DOWN ARE THE MAIN LONG TERM POINTS OF EMPHASIS TODAY. SHORT TERM...TODAY AND TONIGHT... AN ACTIVE ELEVATED WARM AND MOIST ADVECTION ZONE SUPPORTING AREAS OF CONVECTION IS OVER THE REGION EARLY THIS MORNING. A SHORT WAVE DISTURBANCE IN EASTERN IA AS OF 330 AM HAS BEEN AN INSTIGATOR FOR MORE ORGANIZED CONVECTION OVER THE DVN CWA. A BROAD BUT STRONG 45KT LOW-LEVEL JET IS ADVECTING IN MOIST AIR AT THE BASE OF STEEPENING MID-LEVEL LAPSE RATES OF 7-8 C/KM. THIS WILL REMAIN SUPPORTIVE OF WIDESPREAD CONVECTIVE UPDRAFTS THROUGH 8-9 AM BEFORE A PROBABLE DIMINISHING TREND AS STORMS APPROACH/MOVE OVER CHICAGO AND THE I-55 CORRIDOR. A RAP ANALYSIS INDICATES FAIRLY SHORT CORFIDI PROPAGATION VECTORS WITH NORTHWEST MID-LEVEL FLOW PERPENDICULAR TO THE LLJ. SO ISOLATED HEAVY RAIN CONCERNS WILL BE PRESENT AND HAVE BEEN SUPPORTED ON REGIONAL RADAR TRENDS. HAVE INCREASED QPF IN TANDEM WITH HIGHER POPS THROUGH MID-MORNING. A STRENGTHENING CAP ALONG WITH THE WEAKENING/EXIT OF THE AFOREMENTIONED SHORT WAVE SHOULD LIMIT ANY CONVECTIVE CHANCES THIS AFTERNOON. HOWEVER...SOME CLOUDS MAY LINGER INTO EARLY AFTERNOON. WITH THAT AND SOME COMMUNITIES SEEING A SLOWER WARMING TREND EARLY THIS MORNING WITH CLOUDS AND RAIN...HAVE LOWERED TEMPERATURES IN THE NORTHEAST HALF OF THE FORECAST AREA BY A COUPLE DEGREES. TEMPERATURES SHOULD STILL REALIZE 90 IN FAR WESTERN/SOUTHWESTERN AREAS BASED ON 850/925MB TEMPERATURE CLIMATOLOGY AND SUPPORT FROM PAST SIMILAR EVENTS PER THE CIPS ANALOGS. HEAT INDEX READINGS IN THIS AREA...FROM BYRON TO GIBSON CITY AND WESTWARD...WILL LIKELY APPROACH 100 DEGREES DUE TO FORECAST LOWER 70 DEW POINTS. A QUIET AND MILD EVENING IS EXPECTED. CONFIDENCE FOR PRECIP REMAINING OUT OF THE AREA OVERNIGHT IS LOW. WHILE FRONTAL CONVERGENCE REMAINS OFF TO THE NORTHWEST...QUITE A BIT OF ELEVATED INSTABILITY WILL BE PRESENT AND OVERALL FORCING FOR PRECIP IS LOW. BUT AS WE HAVE SEEN EARLY THIS MORNING...EVEN A SUBTLE WAVE CAN CAUSE PROBLEMS. SO CONTINUE CHANCE POPS. MTF LONG TERM FRIDAY THROUGH WEDNESDAY... THE MAIN FORECAST CONCERNS DURING THE LONG TERM PERIOD FOCUS ON THE THREAT FOR SHOWERS AND THUNDERSTORMS...SOME POSSIBLY STRONG...AND THE THREAT OF HEAVY RAINFALL FRIDAY AND FRIDAY NIGHT. SURFACE LOW PRESSURE CURRENTLY ACROSS THE EASTERN DAKOTAS WILL SHIFT NORTHEASTWARD TO NEAR JAMES BAY BY THE START OF THE PERIOD (FRIDAY MORNING). THIS LOW WILL DRIVE A COLD FRONT SOUTHWARD OVER NORTHERN ILLINOIS BY EARLY FRIDAY AFTERNOON. THE TIMING OF THIS FRONTAL PASSAGE SHOULD ALLOW THE HEAT AND HUMIDITY TO LINGER...AT LEAST FOR THE FIRST HALF OF THE DAY...ESPECIALLY ACROSS MY SOUTHERN AREAS. THEREFORE...HIGHS ON FRIDAY LOOK TO ONCE AGAIN CREEP NEAR THE 90 DEGREE MARK...WITH HEAT INDICIES OF 95 TO 100 SOUTH OF INTERSTATE 80. THUNDERSTORMS WILL LIKELY FIRE ACROSS FAR NORTHERN ILLINOIS EARLY ON FRIDAY AS THE FRONT APPROACHES...AND LIKELY INCREASE IN AREAL COVERAGE BY FRIDAY AFTERNOON. SURFACE BASED STORMS APPEAR LIKELY...AHEAD OF THE FRONTAL BOUNDARY LATER FRIDAY MORNING AND INTO THE AFTERNOON...WITH THE PREFRONTAL HIGH THETA-E LOWER LEVEL AIR MASS EXPECTED TO INDUCE MLCAPES OF 2000-3000 J/KG. ALTHOUGH DEEP LAYER SHEAR WILL BE SOMEWHAT LACKLUSTER...WITH ONLY AROUND 25 KT OF 0-6 KM BULK SHEAR...THERE WILL BE A SMALL THREAT FOR MULTI-CELL CLUSTERS CAPABLE OF PRODUCE STRONG WINDS. HOWEVER...IT APPEAR THE MAIN THREAT FOR THIS MAY REMAIN SOUTH OF THE CHICAGO AND ROCKFORD AREAS. THE OTHER THREAT WITH THESE STORMS...AS HAS BEEN THE CASE WITH STORMS FOR THE LAST FEW WEEKS...IS VERY HEAVY RAINFALL. THE HIGH THETA E AIR MASS FEATURING PWAT VALUES OF 1.8 TO 2 INCHES WILL LEAD TO VERY EFFICIENT RAINFALL RATES...AND THIS COUPLED WITH THE FACT THAT THE STEERING LAYER FLOW LOOKS TO RUN NEARLY PARALLEL TO THE SURFACE FRONTAL ZONE...TRAINING CELLS ARE A GOOD POSSIBILITY. IT ALSO APPEARS THAT SHOWERS...POSSIBLY WITH SOME EMBEDDED ELEVATED THUNDERSTORMS...WILL LIKELY CONTINUE IN THE WAKE OF THE SURFACE BOUNDARY INTO FRIDAY NIGHT AS AN ANA-LIKE FRONTAL PRECIP EVENT SETS UP. MID LEVEL FGEN AND THE PROXIMATELY TO THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET ALL POINT TO CONTINUED FORCING TO SUPPORT PRECIP INTO FRIDAY NIGHT. GIVEN THE POSSIBILITIES OF A PERIOD OF VERY HEAVY RAINFALL...WITH POSSIBLE TRAINING OF CELLS AHEAD OF THE FRONT...FOLLOWED BY A LONGER PERIOD OF MODERATE PRECIP INTO FRIDAY NIGHT...HYDRO ISSUES COULD BECOME A CONCERN. THINGS QUIET DOWN AND BECOME MUCH COOLER FOR THE WEEKEND UNDER NORTHERN FLOW. HIGH TEMPERATURES BY SATURDAY AND SUNDAY LOOK TO BE IN THE LOW TO MID 70S. OVERNIGHT TEMPERATURES INTO SUNDAY MORNING LOOKS TO BE QUITE CHILLY AS A SURFACE HIGH BUILDS OVERHEAD. THIS LOOKS TO SET UP WIDESPREAD LOWER 50 DEGREE TEMPERATURES OUTSIDE OF CHICAGO...WITH EVEN A FEW UPPER 40 DEGREE READINGS POSSIBLE IN THE WESTERN SUBURBS. TEMPERATURES LOOK TO MODERATE A BIT BACK INTO THE UPPER 70S INTO NEXT WEEK. THE NEXT CHANCE FOR STORMS LOOKS TO ENTER THE PICTURE AGAIN BY LATE MONDAY NIGHT AND TUESDAY AS ANOTHER DISTURBANCE TAKES AIM ON THE AREA. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * TSRA SLOWLY FADING IN THE LOCAL AREA BUT FIRING ANEW TO THE WEST. * VARIABLE WINDS AND VSBYS/CIGS NEAR STORMS. * VARIABLE WINDS IN THE NEAR TERM BECOMING SOUTHERLY LATER TODAY. LENNING //DISCUSSION...UPDATED 14Z... FAIRLY WIDESPREAD RAIN WITH AREAS OF EMBEDDED THUNDERSTORMS WILL CONTINUE TO MOVE ACROSS THE AREA THIS MORNING. STILL BELIEVE THERE WILL BE A GRADUAL FADE IN COVERAGE TOWARD LATE MORNING INTO EARLY AFTERNOON...BUT IN THE NEAR TERM THINGS ARE HANGING TOGETHER PRETTY WELL. AS PER EARLIER THINKING...THE PREVAILING WIND DIRECTION WILL WANT TO BE SOUTH-SOUTHWEST OUTSIDE OF THE STORMS...AND THE DIRECTION SHOULD FALL BACK INTO THAT DURING THE AFTERNOON. AFTER A QUIET AFTERNOON AND EVENING THERE WILL AGAIN BE A STRONG LOW-LEVEL JET CAPABLE OF LOW-LEVEL WIND SHEAR LATE TONIGHT. THIS ALSO WILL BRING THE POSSIBILITY OF SCATTERED SHRA/TSRA. THE CHANCES WILL INCREASE THROUGH FRIDAY MORNING AS A COLD FRONT APPROACHES FROM THE NORTH. THIS FRONT WILL EVENTUALLY SHIFT WINDS TO THE NORTH TO NORTH-NORTHEAST DURING THE AFTERNOON. //ORD AND MDW CONFIDENCE...UPDATED 16Z... * MEDIUM CONFIDENCE THAT BULK OF TSRA REMAINS AWAY FROM IMMEDIATE TERMINALS BUT HIGH CONFIDENCE IT REMAINS NEARBY INTO EARLY AFTERNOON. * LOW CONFIDENCE IN FUTURE TREND OF CELLS BUILDING IN NW IL. * MEDIUM TO HIGH CONFIDENCE IN SOUTHERLY TREND OF WINDS WITH TEMPO SOUTHEAST NEAR STORMS. LENNING //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...CHANCE OF SHRA AND SLIGHT CHANCE OF TSRA. SATURDAY...VFR. NORTHEAST WINDS. SUNDAY-MONDAY...VFR. TUESDAY-WEDNESDAY...CHANCE OF TSRA. MTF && .MARINE... 155 AM CDT THE WEATHER PATTERN ACROSS THE GREAT LAKES REGION WILL BE A BIT ACTIVE OVER THE NEXT FEW DAYS...WITH SOME PERIODS OF STRONG WINDS IN THE 25 TO 30 KT RANG...ALONG WITH A PERIOD OR TWO OF SHOWERS AND STORMS. A RATHER POTENT EARLY AUTUMN SEASON SURFACE LOW WILL MOVE FROM THE EASTERN DAKOTAS EARLY THIS MORNING TO NEAR JAMES BAY BY EARLY FRIDAY MORNING. THIS SYSTEM WILL CONTINUE TO INDUCE SOME STRONG SOUTHERN WINDS OVER THE LAKE TODAY AND TONIGHT. IT APPEARS THE STRONGEST WINDS UP TO AROUND 30 KT WILL OCCUR THIS EVENING ACROSS THE NORTHERN HALF OF THE LAKE...WITH 20 TO 25 KT SOUTHERLY WINDS OVER THE SOUTHERN HALF OF THE LAKE. THESE STRONG WINDS WILL RESULT IN SMALL CRAFT ADVISORY CONDITIONS INTO THIS EVENING. AS THE LOW SHIFTS OVER THE JAMES BAY FRIDAY MORNING...A TRAILING COLD FRONT WILL SHIFT DOWN THE LAKE DURING THE DAY FRIDAY. WINDS WILL SHIFT NORTHERLY INTO 15 TO 25 KT RANGE LATER FRIDAY AND INTO SATURDAY...BEFORE ABATING LATER SATURDAY AS AN AREA OF SURFACE HIGH PRESSURE BUILDS ACROSS THE SOUTHERN LAKES REGION. THESE NORTHERLY WINDS DOWN THE FETCH OF LAKE MICHIGAN MAY AGAIN RESULT IN SMALL CRAFT ADVISORY CONDITIONS FRIDAY NIGHT AND SATURDAY...WITH WAVES POSSIBLY IN THE 4 TO 7 FT RANGE. THE WEATHER CONDITIONS LOOK TO QUIET DOWN FOR A COUPLE DAYS FOR SUNDAY AND INTO EARLY NEXT WEEK AS SURFACE HIGH PRESSURE DOMINATES ACROSS THE LAKES REGION. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 10 PM THURSDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
920 AM CDT THU SEP 4 2014 .DISCUSSION... 327 AM CDT MORNING THUNDERSTORM COVERAGE AND DURATION ALONG WITH IMPACT ON DAYTIME TEMPERATURES ARE THE SHORT TERM CHALLENGES. THUNDER CHANCES AND DEGREE OF COOL DOWN ARE THE MAIN LONG TERM POINTS OF EMPHASIS TODAY. SHORT TERM...TODAY AND TONIGHT... AN ACTIVE ELEVATED WARM AND MOIST ADVECTION ZONE SUPPORTING AREAS OF CONVECTION IS OVER THE REGION EARLY THIS MORNING. A SHORT WAVE DISTURBANCE IN EASTERN IA AS OF 330 AM HAS BEEN AN INSTIGATOR FOR MORE ORGANIZED CONVECTION OVER THE DVN CWA. A BROAD BUT STRONG 45KT LOW-LEVEL JET IS ADVECTING IN MOIST AIR AT THE BASE OF STEEPENING MID-LEVEL LAPSE RATES OF 7-8 C/KM. THIS WILL REMAIN SUPPORTIVE OF WIDESPREAD CONVECTIVE UPDRAFTS THROUGH 8-9 AM BEFORE A PROBABLE DIMINISHING TREND AS STORMS APPROACH/MOVE OVER CHICAGO AND THE I-55 CORRIDOR. A RAP ANALYSIS INDICATES FAIRLY SHORT CORFIDI PROPAGATION VECTORS WITH NORTHWEST MID-LEVEL FLOW PERPENDICULAR TO THE LLJ. SO ISOLATED HEAVY RAIN CONCERNS WILL BE PRESENT AND HAVE BEEN SUPPORTED ON REGIONAL RADAR TRENDS. HAVE INCREASED QPF IN TANDEM WITH HIGHER POPS THROUGH MID-MORNING. A STRENGTHENING CAP ALONG WITH THE WEAKENING/EXIT OF THE AFOREMENTIONED SHORT WAVE SHOULD LIMIT ANY CONVECTIVE CHANCES THIS AFTERNOON. HOWEVER...SOME CLOUDS MAY LINGER INTO EARLY AFTERNOON. WITH THAT AND SOME COMMUNITIES SEEING A SLOWER WARMING TREND EARLY THIS MORNING WITH CLOUDS AND RAIN...HAVE LOWERED TEMPERATURES IN THE NORTHEAST HALF OF THE FORECAST AREA BY A COUPLE DEGREES. TEMPERATURES SHOULD STILL REALIZE 90 IN FAR WESTERN/SOUTHWESTERN AREAS BASED ON 850/925MB TEMPERATURE CLIMATOLOGY AND SUPPORT FROM PAST SIMILAR EVENTS PER THE CIPS ANALOGS. HEAT INDEX READINGS IN THIS AREA...FROM BYRON TO GIBSON CITY AND WESTWARD...WILL LIKELY APPROACH 100 DEGREES DUE TO FORECAST LOWER 70 DEW POINTS. A QUIET AND MILD EVENING IS EXPECTED. CONFIDENCE FOR PRECIP REMAINING OUT OF THE AREA OVERNIGHT IS LOW. WHILE FRONTAL CONVERGENCE REMAINS OFF TO THE NORTHWEST...QUITE A BIT OF ELEVATED INSTABILITY WILL BE PRESENT AND OVERALL FORCING FOR PRECIP IS LOW. BUT AS WE HAVE SEEN EARLY THIS MORNING...EVEN A SUBTLE WAVE CAN CAUSE PROBLEMS. SO CONTINUE CHANCE POPS. MTF LONG TERM FRIDAY THROUGH WEDNESDAY... THE MAIN FORECAST CONCERNS DURING THE LONG TERM PERIOD FOCUS ON THE THREAT FOR SHOWERS AND THUNDERSTORMS...SOME POSSIBLY STRONG...AND THE THREAT OF HEAVY RAINFALL FRIDAY AND FRIDAY NIGHT. SURFACE LOW PRESSURE CURRENTLY ACROSS THE EASTERN DAKOTAS WILL SHIFT NORTHEASTWARD TO NEAR JAMES BAY BY THE START OF THE PERIOD (FRIDAY MORNING). THIS LOW WILL DRIVE A COLD FRONT SOUTHWARD OVER NORTHERN ILLINOIS BY EARLY FRIDAY AFTERNOON. THE TIMING OF THIS FRONTAL PASSAGE SHOULD ALLOW THE HEAT AND HUMIDITY TO LINGER...AT LEAST FOR THE FIRST HALF OF THE DAY...ESPECIALLY ACROSS MY SOUTHERN AREAS. THEREFORE...HIGHS ON FRIDAY LOOK TO ONCE AGAIN CREEP NEAR THE 90 DEGREE MARK...WITH HEAT INDICIES OF 95 TO 100 SOUTH OF INTERSTATE 80. THUNDERSTORMS WILL LIKELY FIRE ACROSS FAR NORTHERN ILLINOIS EARLY ON FRIDAY AS THE FRONT APPROACHES...AND LIKELY INCREASE IN AREAL COVERAGE BY FRIDAY AFTERNOON. SURFACE BASED STORMS APPEAR LIKELY...AHEAD OF THE FRONTAL BOUNDARY LATER FRIDAY MORNING AND INTO THE AFTERNOON...WITH THE PREFRONTAL HIGH THETA-E LOWER LEVEL AIR MASS EXPECTED TO INDUCE MLCAPES OF 2000-3000 J/KG. ALTHOUGH DEEP LAYER SHEAR WILL BE SOMEWHAT LACKLUSTER...WITH ONLY AROUND 25 KT OF 0-6 KM BULK SHEAR...THERE WILL BE A SMALL THREAT FOR MULTI-CELL CLUSTERS CAPABLE OF PRODUCE STRONG WINDS. HOWEVER...IT APPEAR THE MAIN THREAT FOR THIS MAY REMAIN SOUTH OF THE CHICAGO AND ROCKFORD AREAS. THE OTHER THREAT WITH THESE STORMS...AS HAS BEEN THE CASE WITH STORMS FOR THE LAST FEW WEEKS...IS VERY HEAVY RAINFALL. THE HIGH THETA E AIR MASS FEATURING PWAT VALUES OF 1.8 TO 2 INCHES WILL LEAD TO VERY EFFICIENT RAINFALL RATES...AND THIS COUPLED WITH THE FACT THAT THE STEERING LAYER FLOW LOOKS TO RUN NEARLY PARALLEL TO THE SURFACE FRONTAL ZONE...TRAINING CELLS ARE A GOOD POSSIBILITY. IT ALSO APPEARS THAT SHOWERS...POSSIBLY WITH SOME EMBEDDED ELEVATED THUNDERSTORMS...WILL LIKELY CONTINUE IN THE WAKE OF THE SURFACE BOUNDARY INTO FRIDAY NIGHT AS AN ANA-LIKE FRONTAL PRECIP EVENT SETS UP. MID LEVEL FGEN AND THE PROXIMATELY TO THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET ALL POINT TO CONTINUED FORCING TO SUPPORT PRECIP INTO FRIDAY NIGHT. GIVEN THE POSSIBILITIES OF A PERIOD OF VERY HEAVY RAINFALL...WITH POSSIBLE TRAINING OF CELLS AHEAD OF THE FRONT...FOLLOWED BY A LONGER PERIOD OF MODERATE PRECIP INTO FRIDAY NIGHT...HYDRO ISSUES COULD BECOME A CONCERN. THINGS QUIET DOWN AND BECOME MUCH COOLER FOR THE WEEKEND UNDER NORTHERN FLOW. HIGH TEMPERATURES BY SATURDAY AND SUNDAY LOOK TO BE IN THE LOW TO MID 70S. OVERNIGHT TEMPERATURES INTO SUNDAY MORNING LOOKS TO BE QUITE CHILLY AS A SURFACE HIGH BUILDS OVERHEAD. THIS LOOKS TO SET UP WIDESPREAD LOWER 50 DEGREE TEMPERATURES OUTSIDE OF CHICAGO...WITH EVEN A FEW UPPER 40 DEGREE READINGS POSSIBLE IN THE WESTERN SUBURBS. TEMPERATURES LOOK TO MODERATE A BIT BACK INTO THE UPPER 70S INTO NEXT WEEK. THE NEXT CHANCE FOR STORMS LOOKS TO ENTER THE PICTURE AGAIN BY LATE MONDAY NIGHT AND TUESDAY AS ANOTHER DISTURBANCE TAKES AIM ON THE AREA. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 14Z... * TSRA THROUGH THE MORNING...LIKELY DECREASING EARLY AFTERNOON. * VARIABLE WINDS NEAR THE TSRA...THEN POST CONVECTIVE WIND TRENDS. LENNING //DISCUSSION...UPDATED 14Z... FAIRLY WIDESPREAD RAIN WITH AREAS OF EMBEDDED THUNDERSTORMS WILL CONTINUE TO MOVE ACROSS THE AREA THIS MORNING. STILL BELIEVE THERE WILL BE A GRADUAL FADE IN COVERAGE TOWARD LATE MORNING INTO EARLY AFTERNOON...BUT IN THE NEAR TERM THINGS ARE HANGING TOGETHER PRETTY WELL. AS PER EARLIER THINKING...THE PREVAILING WIND DIRECTION WILL WANT TO BE SOUTH-SOUTHWEST OUTSIDE OF THE STORMS...AND THE DIRECTION SHOULD FALL BACK INTO THAT DURING THE AFTERNOON. AFTER A QUIET AFTERNOON AND EVENING THERE WILL AGAIN BE A STRONG LOW-LEVEL JET CAPABLE OF LOW-LEVEL WIND SHEAR LATE TONIGHT. THIS ALSO WILL BRING THE POSSIBILITY OF SCATTERED SHRA/TSRA. THE CHANCES WILL INCREASE THROUGH FRIDAY MORNING AS A COLD FRONT APPROACHES FROM THE NORTH. THIS FRONT WILL EVENTUALLY SHIFT WINDS TO THE NORTH TO NORTH-NORTHEAST DURING THE AFTERNOON. //ORD AND MDW CONFIDENCE...UPDATED 14Z... * MEDIUM TO HIGH CONFIDENCE IN JUST SHRA WITH VCTS IN THE IMMEDIATE TERM...WITH INCREASING TSRA CHANCES TOWARD LATE MORNING BEFORE ACTIVITY DISSIPATES. * LOW CONFIDENCE IN WIND DIRECTIONS DURING TSRA...THUS THE VRB IN THE TAF. BETTER CONFIDENCE OF BEING LIGHT ENOUGH TO MAINTAIN WEST FLOW AT ORD...AND THEN TRENDING S OR SW THIS AFTERNOON. LENNING //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...CHANCE OF SHRA AND SLIGHT CHANCE OF TSRA. SATURDAY...VFR. NORTHEAST WINDS. SUNDAY-MONDAY...VFR. TUESDAY-WEDNESDAY...CHANCE OF TSRA. MTF && .MARINE... 155 AM CDT THE WEATHER PATTERN ACROSS THE GREAT LAKES REGION WILL BE A BIT ACTIVE OVER THE NEXT FEW DAYS...WITH SOME PERIODS OF STRONG WINDS IN THE 25 TO 30 KT RANG...ALONG WITH A PERIOD OR TWO OF SHOWERS AND STORMS. A RATHER POTENT EARLY AUTUMN SEASON SURFACE LOW WILL MOVE FROM THE EASTERN DAKOTAS EARLY THIS MORNING TO NEAR JAMES BAY BY EARLY FRIDAY MORNING. THIS SYSTEM WILL CONTINUE TO INDUCE SOME STRONG SOUTHERN WINDS OVER THE LAKE TODAY AND TONIGHT. IT APPEARS THE STRONGEST WINDS UP TO AROUND 30 KT WILL OCCUR THIS EVENING ACROSS THE NORTHERN HALF OF THE LAKE...WITH 20 TO 25 KT SOUTHERLY WINDS OVER THE SOUTHERN HALF OF THE LAKE. THESE STRONG WINDS WILL RESULT IN SMALL CRAFT ADVISORY CONDITIONS INTO THIS EVENING. AS THE LOW SHIFTS OVER THE JAMES BAY FRIDAY MORNING...A TRAILING COLD FRONT WILL SHIFT DOWN THE LAKE DURING THE DAY FRIDAY. WINDS WILL SHIFT NORTHERLY INTO 15 TO 25 KT RANGE LATER FRIDAY AND INTO SATURDAY...BEFORE ABATING LATER SATURDAY AS AN AREA OF SURFACE HIGH PRESSURE BUILDS ACROSS THE SOUTHERN LAKES REGION. THESE NORTHERLY WINDS DOWN THE FETCH OF LAKE MICHIGAN MAY AGAIN RESULT IN SMALL CRAFT ADVISORY CONDITIONS FRIDAY NIGHT AND SATURDAY...WITH WAVES POSSIBLY IN THE 4 TO 7 FT RANGE. THE WEATHER CONDITIONS LOOK TO QUIET DOWN FOR A COUPLE DAYS FOR SUNDAY AND INTO EARLY NEXT WEEK AS SURFACE HIGH PRESSURE DOMINATES ACROSS THE LAKES REGION. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 10 PM THURSDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
630 AM CDT THU SEP 4 2014 .DISCUSSION... 327 AM CDT MORNING THUNDERSTORM COVERAGE AND DURATION ALONG WITH IMPACT ON DAYTIME TEMPERATURES ARE THE SHORT TERM CHALLENGES. THUNDER CHANCES AND DEGREE OF COOL DOWN ARE THE MAIN LONG TERM POINTS OF EMPHASIS TODAY. SHORT TERM...TODAY AND TONIGHT... AN ACTIVE ELEVATED WARM AND MOIST ADVECTION ZONE SUPPORTING AREAS OF CONVECTION IS OVER THE REGION EARLY THIS MORNING. A SHORT WAVE DISTURBANCE IN EASTERN IA AS OF 330 AM HAS BEEN AN INSTIGATOR FOR MORE ORGANIZED CONVECTION OVER THE DVN CWA. A BROAD BUT STRONG 45KT LOW-LEVEL JET IS ADVECTING IN MOIST AIR AT THE BASE OF STEEPENING MID-LEVEL LAPSE RATES OF 7-8 C/KM. THIS WILL REMAIN SUPPORTIVE OF WIDESPREAD CONVECTIVE UPDRAFTS THROUGH 8-9 AM BEFORE A PROBABLE DIMINISHING TREND AS STORMS APPROACH/MOVE OVER CHICAGO AND THE I-55 CORRIDOR. A RAP ANALYSIS INDICATES FAIRLY SHORT CORFIDI PROPAGATION VECTORS WITH NORTHWEST MID-LEVEL FLOW PERPENDICULAR TO THE LLJ. SO ISOLATED HEAVY RAIN CONCERNS WILL BE PRESENT AND HAVE BEEN SUPPORTED ON REGIONAL RADAR TRENDS. HAVE INCREASED QPF IN TANDEM WITH HIGHER POPS THROUGH MID-MORNING. A STRENGTHENING CAP ALONG WITH THE WEAKENING/EXIT OF THE AFOREMENTIONED SHORT WAVE SHOULD LIMIT ANY CONVECTIVE CHANCES THIS AFTERNOON. HOWEVER...SOME CLOUDS MAY LINGER INTO EARLY AFTERNOON. WITH THAT AND SOME COMMUNITIES SEEING A SLOWER WARMING TREND EARLY THIS MORNING WITH CLOUDS AND RAIN...HAVE LOWERED TEMPERATURES IN THE NORTHEAST HALF OF THE FORECAST AREA BY A COUPLE DEGREES. TEMPERATURES SHOULD STILL REALIZE 90 IN FAR WESTERN/SOUTHWESTERN AREAS BASED ON 850/925MB TEMPERATURE CLIMATOLOGY AND SUPPORT FROM PAST SIMILAR EVENTS PER THE CIPS ANALOGS. HEAT INDEX READINGS IN THIS AREA...FROM BYRON TO GIBSON CITY AND WESTWARD...WILL LIKELY APPROACH 100 DEGREES DUE TO FORECAST LOWER 70 DEW POINTS. A QUIET AND MILD EVENING IS EXPECTED. CONFIDENCE FOR PRECIP REMAINING OUT OF THE AREA OVERNIGHT IS LOW. WHILE FRONTAL CONVERGENCE REMAINS OFF TO THE NORTHWEST...QUITE A BIT OF ELEVATED INSTABILITY WILL BE PRESENT AND OVERALL FORCING FOR PRECIP IS LOW. BUT AS WE HAVE SEEN EARLY THIS MORNING...EVEN A SUBTLE WAVE CAN CAUSE PROBLEMS. SO CONTINUE CHANCE POPS. MTF LONG TERM FRIDAY THROUGH WEDNESDAY... THE MAIN FORECAST CONCERNS DURING THE LONG TERM PERIOD FOCUS ON THE THREAT FOR SHOWERS AND THUNDERSTORMS...SOME POSSIBLY STRONG...AND THE THREAT OF HEAVY RAINFALL FRIDAY AND FRIDAY NIGHT. SURFACE LOW PRESSURE CURRENTLY ACROSS THE EASTERN DAKOTAS WILL SHIFT NORTHEASTWARD TO NEAR JAMES BAY BY THE START OF THE PERIOD (FRIDAY MORNING). THIS LOW WILL DRIVE A COLD FRONT SOUTHWARD OVER NORTHERN ILLINOIS BY EARLY FRIDAY AFTERNOON. THE TIMING OF THIS FRONTAL PASSAGE SHOULD ALLOW THE HEAT AND HUMIDITY TO LINGER...AT LEAST FOR THE FIRST HALF OF THE DAY...ESPECIALLY ACROSS MY SOUTHERN AREAS. THEREFORE...HIGHS ON FRIDAY LOOK TO ONCE AGAIN CREEP NEAR THE 90 DEGREE MARK...WITH HEAT INDICIES OF 95 TO 100 SOUTH OF INTERSTATE 80. THUNDERSTORMS WILL LIKELY FIRE ACROSS FAR NORTHERN ILLINOIS EARLY ON FRIDAY AS THE FRONT APPROACHES...AND LIKELY INCREASE IN AREAL COVERAGE BY FRIDAY AFTERNOON. SURFACE BASED STORMS APPEAR LIKELY...AHEAD OF THE FRONTAL BOUNDARY LATER FRIDAY MORNING AND INTO THE AFTERNOON...WITH THE PREFRONTAL HIGH THETA-E LOWER LEVEL AIR MASS EXPECTED TO INDUCE MLCAPES OF 2000-3000 J/KG. ALTHOUGH DEEP LAYER SHEAR WILL BE SOMEWHAT LACKLUSTER...WITH ONLY AROUND 25 KT OF 0-6 KM BULK SHEAR...THERE WILL BE A SMALL THREAT FOR MULTI-CELL CLUSTERS CAPABLE OF PRODUCE STRONG WINDS. HOWEVER...IT APPEAR THE MAIN THREAT FOR THIS MAY REMAIN SOUTH OF THE CHICAGO AND ROCKFORD AREAS. THE OTHER THREAT WITH THESE STORMS...AS HAS BEEN THE CASE WITH STORMS FOR THE LAST FEW WEEKS...IS VERY HEAVY RAINFALL. THE HIGH THETA E AIR MASS FEATURING PWAT VALUES OF 1.8 TO 2 INCHES WILL LEAD TO VERY EFFICIENT RAINFALL RATES...AND THIS COUPLED WITH THE FACT THAT THE STEERING LAYER FLOW LOOKS TO RUN NEARLY PARALLEL TO THE SURFACE FRONTAL ZONE...TRAINING CELLS ARE A GOOD POSSIBILITY. IT ALSO APPEARS THAT SHOWERS...POSSIBLY WITH SOME EMBEDDED ELEVATED THUNDERSTORMS...WILL LIKELY CONTINUE IN THE WAKE OF THE SURFACE BOUNDARY INTO FRIDAY NIGHT AS AN ANA-LIKE FRONTAL PRECIP EVENT SETS UP. MID LEVEL FGEN AND THE PROXIMATELY TO THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET ALL POINT TO CONTINUED FORCING TO SUPPORT PRECIP INTO FRIDAY NIGHT. GIVEN THE POSSIBILITIES OF A PERIOD OF VERY HEAVY RAINFALL...WITH POSSIBLE TRAINING OF CELLS AHEAD OF THE FRONT...FOLLOWED BY A LONGER PERIOD OF MODERATE PRECIP INTO FRIDAY NIGHT...HYDRO ISSUES COULD BECOME A CONCERN. THINGS QUIET DOWN AND BECOME MUCH COOLER FOR THE WEEKEND UNDER NORTHERN FLOW. HIGH TEMPERATURES BY SATURDAY AND SUNDAY LOOK TO BE IN THE LOW TO MID 70S. OVERNIGHT TEMPERATURES INTO SUNDAY MORNING LOOKS TO BE QUITE CHILLY AS A SURFACE HIGH BUILDS OVERHEAD. THIS LOOKS TO SET UP WIDESPREAD LOWER 50 DEGREE TEMPERATURES OUTSIDE OF CHICAGO...WITH EVEN A FEW UPPER 40 DEGREE READINGS POSSIBLE IN THE WESTERN SUBURBS. TEMPERATURES LOOK TO MODERATE A BIT BACK INTO THE UPPER 70S INTO NEXT WEEK. THE NEXT CHANCE FOR STORMS LOOKS TO ENTER THE PICTURE AGAIN BY LATE MONDAY NIGHT AND TUESDAY AS ANOTHER DISTURBANCE TAKES AIM ON THE AREA. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * A 2-3 HOUR PERIOD OF RAIN WITH OCCASIONAL EMBEDDED STORMS THIS MORNING. * TEMPORARY WIND SHIFT TO THE NORTHWEST AND THEN POSSIBLY VARIABLE...BEFORE COMING BACK SOUTHERLY. OCCASIONAL GUSTS THROUGHOUT. * CHANCE FOR MORE SHRA/TSRA BEGINNING LATE TONIGHT AND INCREASING THROUGH FRIDAY MORNING. * CHANCE FOR LLWS AGAIN OVERNIGHT. //DISCUSSION...UPDATED 12Z... FAIRLY WIDESPREAD RAIN WITH AREAS OF EMBEDDED THUNDERSTORMS WILL CONTINUE TO SHIFT EAST-SOUTHEAST ACROSS THE AREA THIS MORNING. AFTER 13Z...THERE SHOULD BE A GRADUAL FADE IN COVERAGE OF RAIN AND ESPECIALLY STORMS. STILL...THE STORMS SHOULD IMPACT ORD AND MDW FOR 1.5 TO 3 HOURS. IN ADDITION...ORGANIZED STORMS THAT ARE JUST NORTH OF ORD AT 1130Z DO HAVE AN OUTFLOW BOUNDARY THAT IS PROGRESSING SOUTHWARD AND WILL TURN WINDS NORTHWESTERLY...AT LEAST TEMPORARILY. THE WIND DIRECTION BEHIND THE STORMS MAY BRIEFLY TURN SOUTHEAST AND GUSTY AS IS TYPICAL BEHIND ORGANIZED STORMS...THOUGH THIS SHOULD BE BRIEF /LESS THAN 1-2 HRS/. THE PREVAILING WIND DIRECTION WILL WANT TO BE SOUTH-SOUTHWEST OUTSIDE OF THE STORMS...AND THE DIRECTION SHOULD FALL BACK INTO THAT DURING THE AFTERNOON. AFTER A QUIET AFTERNOON AND EVENING THERE WILL AGAIN BE A STRONG LOW-LEVEL JET CAPABLE OF LOW-LEVEL WIND SHEAR LATE TONIGHT. THIS ALSO WILL BRING THE POSSIBILITY OF SCATTERED SHRA/TSRA. THE CHANCES WILL INCREASE THROUGH FRIDAY MORNING AS A COLD FRONT APPROACHES FROM THE NORTH. THIS FRONT WILL EVENTUALLY SHIFT WINDS TO THE NORTH TO NORTH-NORTHEAST DURING THE AFTERNOON. //ORD AND MDW CONFIDENCE...UPDATED 12Z... * HIGH IN TSRA OCCURRING. MEDIUM IN DURATION OF TSRA. THREE HOURS IS LIKELY ON THE LONGER SIDE OF WHAT IS POSSIBLE...BUT FITS RADAR AND SATELLITE TRENDS. * MEDIUM IN WIND SPEEDS THIS MORNING AND REMAINING IN SOME FORM WESTERLY. IF WINDS DO TURN SOUTHEAST AS THEY SOMETIMES DO AFTER STORMS...IT IS LIKELY TO LAST LESS THAN TWO HOURS. * LOW ON SHRA/TSRA OCCURRING LATE TONIGHT AND FRIDAY MORNING. //OUTLOOK FOR ORD/MDW FOR 00Z SATURDAY-12Z THURSDAY...UPDATED 12Z... FRIDAY NIGHT...CHANCE OF SHRA AND SLIGHT CHANCE OF TSRA. SATURDAY...VFR. NORTHEAST WINDS. SUNDAY-MONDAY...VFR. TUESDAY-WEDNESDAY...CHANCE OF TSRA. MTF && .MARINE... 155 AM CDT THE WEATHER PATTERN ACROSS THE GREAT LAKES REGION WILL BE A BIT ACTIVE OVER THE NEXT FEW DAYS...WITH SOME PERIODS OF STRONG WINDS IN THE 25 TO 30 KT RANG...ALONG WITH A PERIOD OR TWO OF SHOWERS AND STORMS. A RATHER POTENT EARLY AUTUMN SEASON SURFACE LOW WILL MOVE FROM THE EASTERN DAKOTAS EARLY THIS MORNING TO NEAR JAMES BAY BY EARLY FRIDAY MORNING. THIS SYSTEM WILL CONTINUE TO INDUCE SOME STRONG SOUTHERN WINDS OVER THE LAKE TODAY AND TONIGHT. IT APPEARS THE STRONGEST WINDS UP TO AROUND 30 KT WILL OCCUR THIS EVENING ACROSS THE NORTHERN HALF OF THE LAKE...WITH 20 TO 25 KT SOUTHERLY WINDS OVER THE SOUTHERN HALF OF THE LAKE. THESE STRONG WINDS WILL RESULT IN SMALL CRAFT ADVISORY CONDITIONS INTO THIS EVENING. AS THE LOW SHIFTS OVER THE JAMES BAY FRIDAY MORNING...A TRAILING COLD FRONT WILL SHIFT DOWN THE LAKE DURING THE DAY FRIDAY. WINDS WILL SHIFT NORTHERLY INTO 15 TO 25 KT RANGE LATER FRIDAY AND INTO SATURDAY...BEFORE ABATING LATER SATURDAY AS AN AREA OF SURFACE HIGH PRESSURE BUILDS ACROSS THE SOUTHERN LAKES REGION. THESE NORTHERLY WINDS DOWN THE FETCH OF LAKE MICHIGAN MAY AGAIN RESULT IN SMALL CRAFT ADVISORY CONDITIONS FRIDAY NIGHT AND SATURDAY...WITH WAVES POSSIBLY IN THE 4 TO 7 FT RANGE. THE WEATHER CONDITIONS LOOK TO QUIET DOWN FOR A COUPLE DAYS FOR SUNDAY AND INTO EARLY NEXT WEEK AS SURFACE HIGH PRESSURE DOMINATES ACROSS THE LAKES REGION. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...10 AM THURSDAY TO 10 PM THURSDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
417 AM CDT THU SEP 4 2014 .DISCUSSION... 327 AM CDT MORNING THUNDERSTORM COVERAGE AND DURATION ALONG WITH IMPACT ON DAYTIME TEMPERATURES ARE THE SHORT TERM CHALLENGES. THUNDER CHANCES AND DEGREE OF COOL DOWN ARE THE MAIN LONG TERM POINTS OF EMPHASIS TODAY. SHORT TERM...TODAY AND TONIGHT... AN ACTIVE ELEVATED WARM AND MOIST ADVECTION ZONE SUPPORTING AREAS OF CONVECTION IS OVER THE REGION EARLY THIS MORNING. A SHORT WAVE DISTURBANCE IN EASTERN IA AS OF 330 AM HAS BEEN AN INSTIGATOR FOR MORE ORGANIZED CONVECTION OVER THE DVN CWA. A BROAD BUT STRONG 45KT LOW-LEVEL JET IS ADVECTING IN MOIST AIR AT THE BASE OF STEEPENING MID-LEVEL LAPSE RATES OF 7-8 C/KM. THIS WILL REMAIN SUPPORTIVE OF WIDESPREAD CONVECTIVE UPDRAFTS THROUGH 8-9 AM BEFORE A PROBABLE DIMINISHING TREND AS STORMS APPROACH/MOVE OVER CHICAGO AND THE I-55 CORRIDOR. A RAP ANALYSIS INDICATES FAIRLY SHORT CORFIDI PROPAGATION VECTORS WITH NORTHWEST MID-LEVEL FLOW PERPENDICULAR TO THE LLJ. SO ISOLATED HEAVY RAIN CONCERNS WILL BE PRESENT AND HAVE BEEN SUPPORTED ON REGIONAL RADAR TRENDS. HAVE INCREASED QPF IN TANDEM WITH HIGHER POPS THROUGH MID-MORNING. A STRENGTHENING CAP ALONG WITH THE WEAKENING/EXIT OF THE AFOREMENTIONED SHORT WAVE SHOULD LIMIT ANY CONVECTIVE CHANCES THIS AFTERNOON. HOWEVER...SOME CLOUDS MAY LINGER INTO EARLY AFTERNOON. WITH THAT AND SOME COMMUNITIES SEEING A SLOWER WARMING TREND EARLY THIS MORNING WITH CLOUDS AND RAIN...HAVE LOWERED TEMPERATURES IN THE NORTHEAST HALF OF THE FORECAST AREA BY A COUPLE DEGREES. TEMPERATURES SHOULD STILL REALIZE 90 IN FAR WESTERN/SOUTHWESTERN AREAS BASED ON 850/925MB TEMPERATURE CLIMATOLOGY AND SUPPORT FROM PAST SIMILAR EVENTS PER THE CIPS ANALOGS. HEAT INDEX READINGS IN THIS AREA...FROM BYRON TO GIBSON CITY AND WESTWARD...WILL LIKELY APPROACH 100 DEGREES DUE TO FORECAST LOWER 70 DEW POINTS. A QUIET AND MILD EVENING IS EXPECTED. CONFIDENCE FOR PRECIP REMAINING OUT OF THE AREA OVERNIGHT IS LOW. WHILE FRONTAL CONVERGENCE REMAINS OFF TO THE NORTHWEST...QUITE A BIT OF ELEVATED INSTABILITY WILL BE PRESENT AND OVERALL FORCING FOR PRECIP IS LOW. BUT AS WE HAVE SEEN EARLY THIS MORNING...EVEN A SUBTLE WAVE CAN CAUSE PROBLEMS. SO CONTINUE CHANCE POPS. MTF LONG TERM FRIDAY THROUGH WEDNESDAY... THE MAIN FORECAST CONCERNS DURING THE LONG TERM PERIOD FOCUS ON THE THREAT FOR SHOWERS AND THUNDERSTORMS...SOME POSSIBLY STRONG...AND THE THREAT OF HEAVY RAINFALL FRIDAY AND FRIDAY NIGHT. SURFACE LOW PRESSURE CURRENTLY ACROSS THE EASTERN DAKOTAS WILL SHIFT NORTHEASTWARD TO NEAR JAMES BAY BY THE START OF THE PERIOD (FRIDAY MORNING). THIS LOW WILL DRIVE A COLD FRONT SOUTHWARD OVER NORTHERN ILLINOIS BY EARLY FRIDAY AFTERNOON. THE TIMING OF THIS FRONTAL PASSAGE SHOULD ALLOW THE HEAT AND HUMIDITY TO LINGER...AT LEAST FOR THE FIRST HALF OF THE DAY...ESPECIALLY ACROSS MY SOUTHERN AREAS. THEREFORE...HIGHS ON FRIDAY LOOK TO ONCE AGAIN CREEP NEAR THE 90 DEGREE MARK...WITH HEAT INDICIES OF 95 TO 100 SOUTH OF INTERSTATE 80. THUNDERSTORMS WILL LIKELY FIRE ACROSS FAR NORTHERN ILLINOIS EARLY ON FRIDAY AS THE FRONT APPROACHES...AND LIKELY INCREASE IN AREAL COVERAGE BY FRIDAY AFTERNOON. SURFACE BASED STORMS APPEAR LIKELY...AHEAD OF THE FRONTAL BOUNDARY LATER FRIDAY MORNING AND INTO THE AFTERNOON...WITH THE PREFRONTAL HIGH THETA-E LOWER LEVEL AIR MASS EXPECTED TO INDUCE MLCAPES OF 2000-3000 J/KG. ALTHOUGH DEEP LAYER SHEAR WILL BE SOMEWHAT LACKLUSTER...WITH ONLY AROUND 25 KT OF 0-6 KM BULK SHEAR...THERE WILL BE A SMALL THREAT FOR MULTI-CELL CLUSTERS CAPABLE OF PRODUCE STRONG WINDS. HOWEVER...IT APPEAR THE MAIN THREAT FOR THIS MAY REMAIN SOUTH OF THE CHICAGO AND ROCKFORD AREAS. THE OTHER THREAT WITH THESE STORMS...AS HAS BEEN THE CASE WITH STORMS FOR THE LAST FEW WEEKS...IS VERY HEAVY RAINFALL. THE HIGH THETA E AIR MASS FEATURING PWAT VALUES OF 1.8 TO 2 INCHES WILL LEAD TO VERY EFFICIENT RAINFALL RATES...AND THIS COUPLED WITH THE FACT THAT THE STEERING LAYER FLOW LOOKS TO RUN NEARLY PARALLEL TO THE SURFACE FRONTAL ZONE...TRAINING CELLS ARE A GOOD POSSIBILITY. IT ALSO APPEARS THAT SHOWERS...POSSIBLY WITH SOME EMBEDDED ELEVATED THUNDERSTORMS...WILL LIKELY CONTINUE IN THE WAKE OF THE SURFACE BOUNDARY INTO FRIDAY NIGHT AS AN ANA-LIKE FRONTAL PRECIP EVENT SETS UP. MID LEVEL FGEN AND THE PROXIMATELY TO THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET ALL POINT TO CONTINUED FORCING TO SUPPORT PRECIP INTO FRIDAY NIGHT. GIVEN THE POSSIBILITIES OF A PERIOD OF VERY HEAVY RAINFALL...WITH POSSIBLE TRAINING OF CELLS AHEAD OF THE FRONT...FOLLOWED BY A LONGER PERIOD OF MODERATE PRECIP INTO FRIDAY NIGHT...HYDRO ISSUES COULD BECOME A CONCERN. THINGS QUIET DOWN AND BECOME MUCH COOLER FOR THE WEEKEND UNDER NORTHERN FLOW. HIGH TEMPERATURES BY SATURDAY AND SUNDAY LOOK TO BE IN THE LOW TO MID 70S. OVERNIGHT TEMPERATURES INTO SUNDAY MORNING LOOKS TO BE QUITE CHILLY AS A SURFACE HIGH BUILDS OVERHEAD. THIS LOOKS TO SET UP WIDESPREAD LOWER 50 DEGREE TEMPERATURES OUTSIDE OF CHICAGO...WITH EVEN A FEW UPPER 40 DEGREE READINGS POSSIBLE IN THE WESTERN SUBURBS. TEMPERATURES LOOK TO MODERATE A BIT BACK INTO THE UPPER 70S INTO NEXT WEEK. THE NEXT CHANCE FOR STORMS LOOKS TO ENTER THE PICTURE AGAIN BY LATE MONDAY NIGHT AND TUESDAY AS ANOTHER DISTURBANCE TAKES AIM ON THE AREA. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * LOW-LEVEL WIND SHEAR THROUGH 12Z-13Z. * SCATTERED TSRA THROUGH MID-MORNING. WITH WIDESPREAD TSRA TO THE SOUTHWEST/WEST AND NORTH. * GUSTY SSW WINDS THIS AFTERNOON. * SMALL CHANCE FOR SHRA/TSRA AGAIN NEAR DAYBREAK FRIDAY. //DISCUSSION...UPDATED 09Z... HAVE ADDED A TEMPO TSRA AT ORD. WHILE CONFIDENCE REMAINS LOW IF TSRA WILL ACTUALLY OCCUR RIGHT AT THE AIRFIELD...THE COVERAGE OF TSRA CONTINUES TO BE NUMEROUS TO WIDESPREAD TO THE WEST IN A BAND OF WARM AND MOIST ADVECTION. THIS FORCING WILL POINT TOWARD CHICAGO AFTER DAYBREAK. IN ADDITION...WIDESPREAD THUNDERSTORM COVERAGE IS EXPECTED TO THE SOUTHWEST AND POSSIBLY WEST...AS WELL AS TO THE NORTH /JUST NORTH OF THE WI STATE LINE/ THROUGH 13Z-14Z. PREV DISCUSSION...UPDATED 06Z... A POSSIBLY ACTIVE COUPLE/FEW HOURS OF SOME TSRA MAY OCCUR THIS MORNING AFTER DAYBREAK. FIRST...SOUTHERLY WINDS AT 1500-2500 FT HAVE BEEN OBSERVED ON DOPPLER RADAR AND AIRCRAFT AT 40-45 KT FROM MULTIPLE AIRPORTS ACROSS NORTHERN IL AND EASTERN IA. WHILE THERE IS SURFACE SOUTHERLY FLOW...THE RATE OF INCREASE IN WIND SPEED WITH HEIGHT APPEARS TO BE QUITE SHARP...SO HAVE ADDED LOW-LEVEL WIND SHEAR MENTION INTO THE AREA TAFS. OF LARGER CONCERN IS INCREASING MOISTURE AND INSTABILITY ALOFT BY SUNRISE INTO THE MID- MORNING HOURS. THIS IS IN TANDEM WITH THE PASSAGE OF AN UPPER LEVEL DISTURBANCE. THIS SETUP COULD FAVOR EVOLUTION OF THUNDERSTORMS FROM EASTERN IA AND SOUTHERN WI OVER THE AREA. CONFIDENCE IS LOW ON EXACTLY WHAT COVERAGE WOULD BE...BUT AT THIS TIME WOULD BE SURPRISED TO NOT HAVE AT LEAST ISOLATED SHRA/TSRA OCCURRING IN THE 11Z-16Z WINDOW OVER NORTH CENTRAL/NORTHEAST IL. ANY ACTIVITY SHOULD SEE A QUICK WEAKENING TREND LATER IN THE MORNING AND EARLY AFTERNOON AS IT EVOLVES SOUTHEAST. AGAIN...CONFIDENCE ON THIS IS FAIRLY LOW...BUT WORTH NOTING AT LEAST VCTS IN TAFS...AND CONTINUE THE TSRA MENTION AT ROCKFORD. SOUTH-SOUTHWEST SURFACE WINDS SHOULD BECOME GUSTY BY LATE MORNING OR EARLY AFTERNOON AND PERSIST THROUGH THE AFTERNOON AND POSSIBLY EVEN EARLY EVE. THE WIND DIRECTION MAY OCCASIONALLY BE NEAR 180 DEGREES. OTHERWISE...THE EVENING INTO THE OVERNIGHT SHOULD BE FAIRLY QUIET...WITH A SYSTEM COLD FRONT EXPECTED TO ARRIVE AFTER DAYBREAK FRIDAY...BRINGING SHRA/TSRA CHANCE DURING THE DAY. //ORD AND MDW CONFIDENCE...UPDATED 09Z... * HIGH IN 40-45 KT SSW FLOW AROUND 1500-2500 FT THROUGH DAYBREAK. * HIGH IN SCATTERED TSRA THROUGH 13Z-15Z. LOW IN WHETHER TSRA WILL OCCUR OVER THE AIRFIELDS. * HIGH IN WINDS. * LOW IN ANY SHRA/TSRA OCCURRING AGAIN LATE THURSDAY NIGHT. //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...CHC TSRA. SATURDAY THROUGH MONDAY...VFR TUESDAY...CHC TSRA. MTF/BMD && .MARINE... 155 AM CDT THE WEATHER PATTERN ACROSS THE GREAT LAKES REGION WILL BE A BIT ACTIVE OVER THE NEXT FEW DAYS...WITH SOME PERIODS OF STRONG WINDS IN THE 25 TO 30 KT RANG...ALONG WITH A PERIOD OR TWO OF SHOWERS AND STORMS. A RATHER POTENT EARLY AUTUMN SEASON SURFACE LOW WILL MOVE FROM THE EASTERN DAKOTAS EARLY THIS MORNING TO NEAR JAMES BAY BY EARLY FRIDAY MORNING. THIS SYSTEM WILL CONTINUE TO INDUCE SOME STRONG SOUTHERN WINDS OVER THE LAKE TODAY AND TONIGHT. IT APPEARS THE STRONGEST WINDS UP TO AROUND 30 KT WILL OCCUR THIS EVENING ACROSS THE NORTHERN HALF OF THE LAKE...WITH 20 TO 25 KT SOUTHERLY WINDS OVER THE SOUTHERN HALF OF THE LAKE. THESE STRONG WINDS WILL RESULT IN SMALL CRAFT ADVISORY CONDITIONS INTO THIS EVENING. AS THE LOW SHIFTS OVER THE JAMES BAY FRIDAY MORNING...A TRAILING COLD FRONT WILL SHIFT DOWN THE LAKE DURING THE DAY FRIDAY. WINDS WILL SHIFT NORTHERLY INTO 15 TO 25 KT RANGE LATER FRIDAY AND INTO SATURDAY...BEFORE ABATING LATER SATURDAY AS AN AREA OF SURFACE HIGH PRESSURE BUILDS ACROSS THE SOUTHERN LAKES REGION. THESE NORTHERLY WINDS DOWN THE FETCH OF LAKE MICHIGAN MAY AGAIN RESULT IN SMALL CRAFT ADVISORY CONDITIONS FRIDAY NIGHT AND SATURDAY...WITH WAVES POSSIBLY IN THE 4 TO 7 FT RANGE. THE WEATHER CONDITIONS LOOK TO QUIET DOWN FOR A COUPLE DAYS FOR SUNDAY AND INTO EARLY NEXT WEEK AS SURFACE HIGH PRESSURE DOMINATES ACROSS THE LAKES REGION. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...10 AM THURSDAY TO 10 PM THURSDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
328 AM CDT THU SEP 4 2014 .DISCUSSION... 327 AM CDT MORNING THUNDERSTORM COVERAGE AND DURATION ALONG WITH IMPACT ON DAYTIME TEMPERATURES ARE THE SHORT TERM CHALLENGES. THUNDER CHANCES AND DEGREE OF COOL DOWN ARE THE MAIN LONG TERM POINTS OF EMPHASIS TODAY. SHORT TERM...TODAY AND TONIGHT... AN ACTIVE ELEVATED WARM AND MOIST ADVECTION ZONE SUPPORTING AREAS OF CONVECTION IS OVER THE REGION EARLY THIS MORNING. A SHORT WAVE DISTURBANCE IN EASTERN IA AS OF 330 AM HAS BEEN AN INSTIGATOR FOR MORE ORGANIZED CONVECTION OVER THE DVN CWA. A BROAD BUT STRONG 45KT LOW-LEVEL JET IS ADVECTING IN MOIST AIR AT THE BASE OF STEEPENING MID-LEVEL LAPSE RATES OF 7-8 C/KM. THIS WILL REMAIN SUPPORTIVE OF WIDESPREAD CONVECTIVE UPDRAFTS THROUGH 8-9 AM BEFORE A PROBABLE DIMINISHING TREND AS STORMS APPROACH/MOVE OVER CHICAGO AND THE I-55 CORRIDOR. A RAP ANALYSIS INDICATES FAIRLY SHORT CORFIDI PROPAGATION VECTORS WITH NORTHWEST MID-LEVEL FLOW PERPENDICULAR TO THE LLJ. SO ISOLATED HEAVY RAIN CONCERNS WILL BE PRESENT AND HAVE BEEN SUPPORTED ON REGIONAL RADAR TRENDS. HAVE INCREASED QPF IN TANDEM WITH HIGHER POPS THROUGH MID-MORNING. A STRENGTHENING CAP ALONG WITH THE WEAKENING/EXIT OF THE AFOREMENTIONED SHORT WAVE SHOULD LIMIT ANY CONVECTIVE CHANCES THIS AFTERNOON. HOWEVER...SOME CLOUDS MAY LINGER INTO EARLY AFTERNOON. WITH THAT AND SOME COMMUNITIES SEEING A SLOWER WARMING TREND EARLY THIS MORNING WITH CLOUDS AND RAIN...HAVE LOWERED TEMPERATURES IN THE NORTHEAST HALF OF THE FORECAST AREA BY A COUPLE DEGREES. TEMPERATURES SHOULD STILL REALIZE 90 IN FAR WESTERN/SOUTHWESTERN AREAS BASED ON 850/925MB TEMPERATURE CLIMATOLOGY AND SUPPORT FROM PAST SIMILAR EVENTS PER THE CIPS ANALOGS. HEAT INDEX READINGS IN THIS AREA...FROM BYRON TO GIBSON CITY AND WESTWARD...WILL LIKELY APPROACH 100 DEGREES DUE TO FORECAST LOWER 70 DEW POINTS. A QUIET AND MILD EVENING IS EXPECTED. CONFIDENCE FOR PRECIP REMAINING OUT OF THE AREA OVERNIGHT IS LOW. WHILE FRONTAL CONVERGENCE REMAINS OFF TO THE NORTHWEST...QUITE A BIT OF ELEVATED INSTABILITY WILL BE PRESENT AND OVERALL FORCING FOR PRECIP IS LOW. BUT AS WE HAVE SEEN EARLY THIS MORNING...EVEN A SUBTLE WAVE CAN CAUSE PROBLEMS. SO CONTINUE CHANCE POPS. MTF LONG TERM FRIDAY THROUGH WEDNESDAY... THE MAIN FORECAST CONCERNS DURING THE LONG TERM PERIOD FOCUS ON THE THREAT FOR SHOWERS AND THUNDERSTORMS...SOME POSSIBLY STRONG...AND THE THREAT OF HEAVY RAINFALL FRIDAY AND FRIDAY NIGHT. SURFACE LOW PRESSURE CURRENTLY ACROSS THE EASTERN DAKOTAS WILL SHIFT NORTHEASTWARD TO NEAR JAMES BAY BY THE START OF THE PERIOD (FRIDAY MORNING). THIS LOW WILL DRIVE A COLD FRONT SOUTHWARD OVER NORTHERN ILLINOIS BY EARLY FRIDAY AFTERNOON. THE TIMING OF THIS FRONTAL PASSAGE SHOULD ALLOW THE HEAT AND HUMIDITY TO LINGER...AT LEAST FOR THE FIRST HALF OF THE DAY...ESPECIALLY ACROSS MY SOUTHERN AREAS. THEREFORE...HIGHS ON FRIDAY LOOK TO ONCE AGAIN CREEP NEAR THE 90 DEGREE MARK...WITH HEAT INDICIES OF 95 TO 100 SOUTH OF INTERSTATE 80. THUNDERSTORMS WILL LIKELY FIRE ACROSS FAR NORTHERN ILLINOIS EARLY ON FRIDAY AS THE FRONT APPROACHES...AND LIKELY INCREASE IN AREAL COVERAGE BY FRIDAY AFTERNOON. SURFACE BASED STORMS APPEAR LIKELY...AHEAD OF THE FRONTAL BOUNDARY LATER FRIDAY MORNING AND INTO THE AFTERNOON...WITH THE PREFRONTAL HIGH THETA-E LOWER LEVEL AIR MASS EXPECTED TO INDUCE MLCAPES OF 2000-3000 J/KG. ALTHOUGH DEEP LAYER SHEAR WILL BE SOMEWHAT LACKLUSTER...WITH ONLY AROUND 25 KT OF 0-6 KM BULK SHEAR...THERE WILL BE A SMALL THREAT FOR MULTI-CELL CLUSTERS CAPABLE OF PRODUCE STRONG WINDS. HOWEVER...IT APPEAR THE MAIN THREAT FOR THIS MAY REMAIN SOUTH OF THE CHICAGO AND ROCKFORD AREAS. THE OTHER THREAT WITH THESE STORMS...AS HAS BEEN THE CASE WITH STORMS FOR THE LAST FEW WEEKS...IS VERY HEAVY RAINFALL. THE HIGH THETA E AIR MASS FEATURING PWAT VALUES OF 1.8 TO 2 INCHES WILL LEAD TO VERY EFFICIENT RAINFALL RATES...AND THIS COUPLED WITH THE FACT THAT THE STEERING LAYER FLOW LOOKS TO RUN NEARLY PARALLEL TO THE SURFACE FRONTAL ZONE...TRAINING CELLS ARE A GOOD POSSIBILITY. IT ALSO APPEARS THAT SHOWERS...POSSIBLY WITH SOME EMBEDDED ELEVATED THUNDERSTORMS...WILL LIKELY CONTINUE IN THE WAKE OF THE SURFACE BOUNDARY INTO FRIDAY NIGHT AS AN ANA-LIKE FRONTAL PRECIP EVENT SETS UP. MID LEVEL FGEN AND THE PROXIMATELY TO THE RIGHT ENTRANCE REGION OF THE UPPER LEVEL JET ALL POINT TO CONTINUED FORCING TO SUPPORT PRECIP INTO FRIDAY NIGHT. GIVEN THE POSSIBILITIES OF A PERIOD OF VERY HEAVY RAINFALL...WITH POSSIBLE TRAINING OF CELLS AHEAD OF THE FRONT...FOLLOWED BY A LONGER PERIOD OF MODERATE PRECIP INTO FRIDAY NIGHT...HYDRO ISSUES COULD BECOME A CONCERN. THINGS QUIET DOWN AND BECOME MUCH COOLER FOR THE WEEKEND UNDER NORTHERN FLOW. HIGH TEMPERATURES BY SATURDAY AND SUNDAY LOOK TO BE IN THE LOW TO MID 70S. OVERNIGHT TEMPERATURES INTO SUNDAY MORNING LOOKS TO BE QUITE CHILLY AS A SURFACE HIGH BUILDS OVERHEAD. THIS LOOKS TO SET UP WIDESPREAD LOWER 50 DEGREE TEMPERATURES OUTSIDE OF CHICAGO...WITH EVEN A FEW UPPER 40 DEGREE READINGS POSSIBLE IN THE WESTERN SUBURBS. TEMPERATURES LOOK TO MODERATE A BIT BACK INTO THE UPPER 70S INTO NEXT WEEK. THE NEXT CHANCE FOR STORMS LOOKS TO ENTER THE PICTURE AGAIN BY LATE MONDAY NIGHT AND TUESDAY AS ANOTHER DISTURBANCE TAKES AIM ON THE AREA. KJB && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * LOW-LEVEL WIND SHEAR THROUGH 12Z-13Z. * CHANCE FOR SCATTERED OR AREA OF TSRA THIS MORNING AFTER DAYBREAK. * GUSTY SSW WINDS THIS AFTERNOON. * SMALL CHANCE FOR SHRA/TSRA AGAIN NEAR DAYBREAK FRIDAY. //DISCUSSION...UPDATED 06Z... A POSSIBLY ACTIVE COUPLE/FEW HOURS OF SOME TSRA MAY OCCUR THIS MORNING AFTER DAYBREAK. FIRST...SOUTHERLY WINDS AT 1500-2500 FT HAVE BEEN OBSERVED ON DOPPLER RADAR AND AIRCRAFT AT 40-45 KT FROM MULTIPLE AIRPORTS ACROSS NORTHERN IL AND EASTERN IA. WHILE THERE IS SURFACE SOUTHERLY FLOW...THE RATE OF INCREASE IN WIND SPEED WITH HEIGHT APPEARS TO BE QUITE SHARP...SO HAVE ADDED LOW-LEVEL WIND SHEAR MENTION INTO THE AREA TAFS. OF LARGER CONCERN IS INCREASING MOISTURE AND INSTABILITY ALOFT BY SUNRISE INTO THE MID- MORNING HOURS. THIS IS IN TANDEM WITH THE PASSAGE OF AN UPPER LEVEL DISTURBANCE. THIS SETUP COULD FAVOR EVOLUTION OF THUNDERSTORMS FROM EASTERN IA AND SOUTHERN WI OVER THE AREA. CONFIDENCE IS LOW ON EXACTLY WHAT COVERAGE WOULD BE...BUT AT THIS TIME WOULD BE SURPRISED TO NOT HAVE AT LEAST ISOLATED SHRA/TSRA OCCURRING IN THE 11Z-16Z WINDOW OVER NORTH CENTRAL/NORTHEAST IL. ANY ACTIVITY SHOULD SEE A QUICK WEAKENING TREND LATER IN THE MORNING AND EARLY AFTERNOON AS IT EVOLVES SOUTHEAST. AGAIN...CONFIDENCE ON THIS IS FAIRLY LOW...BUT WORTH NOTING AT LEAST VCTS IN TAFS...AND CONTINUE THE TSRA MENTION AT ROCKFORD. SOUTH-SOUTHWEST SURFACE WINDS SHOULD BECOME GUSTY BY LATE MORNING OR EARLY AFTERNOON AND PERSIST THROUGH THE AFTERNOON AND POSSIBLY EVEN EARLY EVE. THE WIND DIRECTION MAY OCCASIONALLY BE NEAR 180 DEGREES. OTHERWISE...THE EVENING INTO THE OVERNIGHT SHOULD BE FAIRLY QUIET...WITH A SYSTEM COLD FRONT EXPECTED TO ARRIVE AFTER DAYBREAK FRIDAY...BRINGING SHRA/TSRA CHANCE DURING THE DAY. //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH IN 40-45 KT SSW FLOW AROUND 1500-2500 FT THROUGH DAYBREAK. * MEDIUM IN VCTS OCCURRING...LOW IN WHAT COVERAGE OF STORMS WILL BE AND IF THEY WILL OCCUR OVER THE AIRFIELDS. * HIGH IN WINDS. * LOW IN ANY SHRA/TSRA OCCURRING AGAIN LATE THURSDAY NIGHT. //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...CHC TSRA. SATURDAY THROUGH MONDAY...VFR TUESDAY...CHC TSRA. MTF/BMD && .MARINE... 155 AM CDT THE WEATHER PATTERN ACROSS THE GREAT LAKES REGION WILL BE A BIT ACTIVE OVER THE NEXT FEW DAYS...WITH SOME PERIODS OF STRONG WINDS IN THE 25 TO 30 KT RANG...ALONG WITH A PERIOD OR TWO OF SHOWERS AND STORMS. A RATHER POTENT EARLY AUTUMN SEASON SURFACE LOW WILL MOVE FROM THE EASTERN DAKOTAS EARLY THIS MORNING TO NEAR JAMES BAY BY EARLY FRIDAY MORNING. THIS SYSTEM WILL CONTINUE TO INDUCE SOME STRONG SOUTHERN WINDS OVER THE LAKE TODAY AND TONIGHT. IT APPEARS THE STRONGEST WINDS UP TO AROUND 30 KT WILL OCCUR THIS EVENING ACROSS THE NORTHERN HALF OF THE LAKE...WITH 20 TO 25 KT SOUTHERLY WINDS OVER THE SOUTHERN HALF OF THE LAKE. THESE STRONG WINDS WILL RESULT IN SMALL CRAFT ADVISORY CONDITIONS INTO THIS EVENING. AS THE LOW SHIFTS OVER THE JAMES BAY FRIDAY MORNING...A TRAILING COLD FRONT WILL SHIFT DOWN THE LAKE DURING THE DAY FRIDAY. WINDS WILL SHIFT NORTHERLY INTO 15 TO 25 KT RANGE LATER FRIDAY AND INTO SATURDAY...BEFORE ABATING LATER SATURDAY AS AN AREA OF SURFACE HIGH PRESSURE BUILDS ACROSS THE SOUTHERN LAKES REGION. THESE NORTHERLY WINDS DOWN THE FETCH OF LAKE MICHIGAN MAY AGAIN RESULT IN SMALL CRAFT ADVISORY CONDITIONS FRIDAY NIGHT AND SATURDAY...WITH WAVES POSSIBLY IN THE 4 TO 7 FT RANGE. THE WEATHER CONDITIONS LOOK TO QUIET DOWN FOR A COUPLE DAYS FOR SUNDAY AND INTO EARLY NEXT WEEK AS SURFACE HIGH PRESSURE DOMINATES ACROSS THE LAKES REGION. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...10 AM THURSDAY TO 10 PM THURSDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
156 AM CDT THU SEP 4 2014 .DISCUSSION... 904 PM CDT ONLY MINOR ADJUSTMENTS TONIGHT. BUT THE GREATEST CHALLENGE RESIDES WITH PRECIP TIMING...COVERAGE. GUIDANCE MEMBERS DIFFERS ON TIMING AND PLACEMENT OF CONVECTION/PRECIP OVERNIGHT. THERE IS A WEAK MID- LVL WAVE SLIDING EAST ACROSS CENTRAL IOWA THAT THE RAP CONTINUES TO LEAN TOWARDS THE FOCAL POINT OVERNIGHT...WITH DEVELOPMENT CLOSER TO MIDNIGHT ALONG THE MISS RIVER. THERE HAS BEEN SOME ISOLATED SHOWERS/THUNDERSTORMS ACROSS SOUTHEAST IOWA SLIDING EAST INTO IL...HOWEVER THE TRENDS HAS BEEN THAT THIS PRECIP WOULD WEAKEN. THE NOSE OF THE LLVL JET AND THETA-E IS LIFTING NORTH...WHICH COUPLED WITH LLVL MOISTURE STEADILY INCREASING WOULD POINT TOWARDS A POTENTIAL FOR INCREASED PRECIP OVERNIGHT OR CLOSER TO 8-12Z. WILL NUDGE POPS UP TO ACCOUNT FOR THIS...WITH THE FOCUS BEING AFT MIDNIGHT AND CLOSER TO DAYBREAK. BEACHLER //PREV DISCUSSION... 252 PM CDT SHORT TERM... FOR THE REMAINDER OF THIS AFTERNOON AND INTO THIS EVENING...QUIET WEATHER CONDITIONS WILL PREVAIL AS SFC HIGH PRESSURE MOVES OFF TO THE EAST AND LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS. ALOFT...BROAD UPPER RIDGING EXTENDS ACROSS THE SRN CONUS WITH ZONAL FLOW OVER THE NRN CONUS. WINDS ACROSS THE AREA AT THE SFC HAVE BEEN VERY LIGHT...WHICH HAS ALLOWED A LAKE BREEZE TO FORM...BUT SLIGHTLY STRONGER WINDS ALOFT HAVE KEPT THE LAKE BREEZE BOUNDARY FROM PUSHING INLAND MUCH FARTHER THAN DOWNTOWN CHICAGO. SO...WHILE MUCH OF THE AREA WILL SEE TEMPERATURES TOP OUT IN THE LOWER TO MIDDLE 80S...THE ILLINOIS LAKEFRONT HAS REMAINED MUCH COOLER WITH HIGHS TODAY TOPPING OUT IN THE MIDDLE 70S. A FEW WEAK SHORT WAVES ARE RIPPLING THROUGH THE ZONAL FLOW...GENERATING AREAS OF SHOWERS AND THUNDERSTORMS...BUT NONE ARE CURRENTLY CLOSE TO THE LOCAL AREA. INTO THIS EVENING...THERE WILL BE AN INCREASING CHANCE FOR THUNDERSTORMS AS MOISTURE STREAMS NWD AROUND THE WRN PERIPHERY OF THE SFC HIGH AS SOUTHERLY FLOW DEVELOPS. BY LATE THIS EVENING...ANTICIPATE A STRONG CONVECTIVE COMPLEX TO DEVELOP OVER THE UPPER MISSISSIPPI VALLEY ON THE LEADING EDGE OF A STRONG LOW LEVEL JET WHERE SPC HAS OUTLOOKED A SLIGHT RISK FOR SEVERE THUNDERSTORMS. THE MAIN QUESTION REMAINS AS TO HOW THE CONVECTIVE COMPLEX WILL EVOLVE THROUGH THE EVENING AND OVERNIGHT. THE ANTICIPATION IS THAT THE SYSTEM MAY DEVELOP INTO A BOWING LINE OR SQUALL LINE OVERNIGHT AND PROPAGATE TO THE SOUTHEAST...ACROSS WISCONSIN. THE LATEST HIGH RES MODEL GUIDANCE...INCLUDING THE LOCAL WRF...SUGGEST THAT THE LINE OF THUNDERSTORMS MAY HANG TOGETHER LONG ENOUGH THE REACH NRN/NWRN IL AFTER MIDNIGHT AND INTO THE EARLY MORNING HOURS BEFORE DISSIPATING. HOWEVER...SINCE THERE IS STILL SOME UNCERTAINTY TO THE TIMING AND TRACK OF THE SYSTEM...HAVE KEPT POPS IN THE CHANCE RANGE AND CONFINED THE MENTION OF PCPN TO THE NRN TIER COUNTIES OF IL ALONG THE WISCONSIN BORDER. WHILE THERE IS STILL A CHANCE THAT SOME STRAY SHOWERS OR THUNDERSTORMS COULD LINGER INTO THE MORNING HOURS TOMORROW...GENERALLY EXPECT THAT THE REST OF THE DAY THURSDAY SHOULD BE DRY. THE MAIN CONCERN FOR THURSDAY WILL BE THE TEMPERATURE FORECAST. THE UPPER LEVEL PATTERN WILL BEGIN TO SHOW SOME AMPLIFICATION AS THE UPPER RIDGE BUILDS ACROSS THE MIDWEST AND GREAT LAKES WHILE AN UPPER LOW MOVING EWD FROM THE PAC NORTHWEST TRACKS ACROSS THE SRN CANADIAN PRAIRIES. THE MAIN EFFECT FOR THE LOCAL AREA WILL BE A CONTINUATION OF PUMPING UP LOW LEVEL MOISTURE...WITH SFC DEWPOINT LIKELY CLIMBING INTO THE LOW 70S. THE VARIOUS AND SUNDRY MODELS ARE IN RELATIVELY GOOD AGREEMENT ON BRINGING 850MB TEMPS OF 22-23C ACROSS THE AREA. UNDER FULL SUNSHINE...THIS WOULD IMPLY MAX TEMPS IN THE LOW 90S. HOWEVER...SOME RESIDUAL CLOUD COVER...EVEN PARTIAL CLOUD COVER...COULD LIMIT SLIGHTLY THE POTENTIAL MAXIMUM WARMING...SO...HAVE MAINTAINED THE GOING FORECAST OF MAX TEMPS IN THE UPPER 80S TO SOME AREAS AROUND 90-91F. THIS COMBINATION OF TEMPERATURES AROUND 90F WITH DEWPOINTS IN THE LOW 70S WOULD GENERATE MAX HEAT INDEX VALUES CLOSE TO 100F. SO...WHILE HEAT ADVISORY CRITERIA WILL LIKELY NOT BE MET...IT WILL CERTAINLY BE A HOT AND HUMID DAY...THE LIKES OF WHICH HAS BEEN FEW AND FAR BETWEEN THIS SUMMER. THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL COME THURSDAY NIGHT AND FRIDAY AS A SFC LOW DEVELOPS OVER THE CNTRL PLAINS TRACKS NORTHEAST ACROSS THE UPPER MISSOURI VALLEY AND INTO THE UPPER MISSISSIPPI VALLEY THURSDAY. THIS SFC LOW WILL DRAG A TRAILING COLD FRONT ACROSS THE UPPER MISSISSIPPI VALLEY BY THURSDAY EVENING. THE MODEL GUIDANCE HAS BEEN RELATIVELY CONSISTENT IN ADVERTISING A RELATIVELY STRONG COLD FRONT ASSOCIATED WITH THE DEEPENING UPPER LEVEL LONGWAVE TROUGH DROPPING INTO THE NRN PLAINS. THIS IS SHAPING UP TO BE A RATHER DYNAMIC SYSTEM WITH STRONG UPPER FORCING WITH THE 100KT+ JET ACROSS THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES...A STRONG MID LEVEL TROUGH AND SFC COLD FRONT. ALSO...THE MODELS ARE SHOWING SIGNIFICANT MOISTURE POOLING AHEAD OF THE SFC FRONT WITH PWATS OF 2 INCHES ALONG THE BOUNDARY. WHILE THE STRONGEST UPPER LEVEL FORCING WILL BE WELL NORTH OF THE CWA...AS SPC OUTLOOKS A SLIGHT RISK OVER WISCONSIN AND THE WESTERN GREAT LAKES IN THE DAY 2 OUTLOOK...SO THE GREATEST SEVERE POTENTIAL SHOULD BE TO THE NORTH...THERE WILL STILL BE THE POTENTIAL FOR STRONG THUNDERSTORMS PRODUCING LOCALLY HEAVY RAINFALL. AS THE SYSTEM SHOULD BE QUICKLY PROGRESSIVE...WIDESPREAD FLOODING SHOULD NOT BE A MAJOR CONCERN...BUT LOCALIZED FLOODING OR FLASH FLOODING IS A POSSIBILITY IF ANY TRAINING SETS UP AS INDIVIDUAL CELLS TRACK NEWD WHILE THE LARGER SCALE SYSTEM PROGRESSES EWD. FORECAST CONFIDENCE BEGINS TO DIMINISH INTO LATE FRIDAY NIGHT AND EARLY SATURDAY AND WHEN THE PCPN WILL CLEAR THE CWA. HAVE GENERALLY BEEN FOLLOWING THE TREND OF THE ECMWF WHICH INDICATES SOME LINGERING PCPN OVER THE SERN PORTIONS OF THE CWA INTO SATURDAY MORNING WHILE THE GFS IS A LITTLE SLOW. CURRENTLY FAVOR A FASTER PROGRESSION GIVEN RELATIVELY LOW AMPLITUDE...FAST FLOW ALOFT...SO...WILL GO DRY BY SATURDAY AFTERNOON. FOR THE LONGER TERM...FROM SATURDAY AFTERNOON AND INTO THE MIDDLE OF NEXT WEEK. EXPECT THAT THE REMAINDER OF THE WEEKEND AND EARLY NEXT WEEK SHOULD BE DRY...BUT ON THE COOLER SIDE AS HIGH PRESSURE BUILDS ACROSS THE MIDWEST WHILE A QUICK MOVING LOW SCOOTS ACROSS THE UPPER GREAT LAKES...SETTING UP LIGHT FLOW OFF OF THE LAKE. BY MONDAY NIGHT AND INTO TUESDAY...ANOTHER SYSTEM IS EXPECTED TO DEVELOP OVER THE CNTRL PLAINS...DRAGGING ANOTHER COLD FRONT ACROSS THE AREA...WHICH WILL BRING CHANCES FOR MORE SHOWERS AND THUNDERSTORMS BY TUESDAY AND WEDNESDAY. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * LOW-LEVEL WIND SHEAR THROUGH 12Z-13Z. * CHANCE FOR SCATTERED OR AREA OF TSRA THIS MORNING AFTER DAYBREAK. * GUSTY SSW WINDS THIS AFTERNOON. * SMALL CHANCE FOR SHRA/TSRA AGAIN NEAR DAYBREAK FRIDAY. //DISCUSSION...UPDATED 06Z... A POSSIBLY ACTIVE COUPLE/FEW HOURS OF SOME TSRA MAY OCCUR THIS MORNING AFTER DAYBREAK. FIRST...SOUTHERLY WINDS AT 1500-2500 FT HAVE BEEN OBSERVED ON DOPPLER RADAR AND AIRCRAFT AT 40-45 KT FROM MULTIPLE AIRPORTS ACROSS NORTHERN IL AND EASTERN IA. WHILE THERE IS SURFACE SOUTHERLY FLOW...THE RATE OF INCREASE IN WIND SPEED WITH HEIGHT APPEARS TO BE QUITE SHARP...SO HAVE ADDED LOW-LEVEL WIND SHEAR MENTION INTO THE AREA TAFS. OF LARGER CONCERN IS INCREASING MOISTURE AND INSTABILITY ALOFT BY SUNRISE INTO THE MID- MORNING HOURS. THIS IS IN TANDEM WITH THE PASSAGE OF AN UPPER LEVEL DISTURBANCE. THIS SETUP COULD FAVOR EVOLUTION OF THUNDERSTORMS FROM EASTERN IA AND SOUTHERN WI OVER THE AREA. CONFIDENCE IS LOW ON EXACTLY WHAT COVERAGE WOULD BE...BUT AT THIS TIME WOULD BE SURPRISED TO NOT HAVE AT LEAST ISOLATED SHRA/TSRA OCCURRING IN THE 11Z-16Z WINDOW OVER NORTH CENTRAL/NORTHEAST IL. ANY ACTIVITY SHOULD SEE A QUICK WEAKENING TREND LATER IN THE MORNING AND EARLY AFTERNOON AS IT EVOLVES SOUTHEAST. AGAIN...CONFIDENCE ON THIS IS FAIRLY LOW...BUT WORTH NOTING AT LEAST VCTS IN TAFS...AND CONTINUE THE TSRA MENTION AT ROCKFORD. SOUTH-SOUTHWEST SURFACE WINDS SHOULD BECOME GUSTY BY LATE MORNING OR EARLY AFTERNOON AND PERSIST THROUGH THE AFTERNOON AND POSSIBLY EVEN EARLY EVE. THE WIND DIRECTION MAY OCCASIONALLY BE NEAR 180 DEGREES. OTHERWISE...THE EVENING INTO THE OVERNIGHT SHOULD BE FAIRLY QUIET...WITH A SYSTEM COLD FRONT EXPECTED TO ARRIVE AFTER DAYBREAK FRIDAY...BRINGING SHRA/TSRA CHANCE DURING THE DAY. //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH IN 40-45 KT SSW FLOW AROUND 1500-2500 FT THROUGH DAYBREAK. * MEDIUM IN VCTS OCCURRING...LOW IN WHAT COVERAGE OF STORMS WILL BE AND IF THEY WILL OCCUR OVER THE AIRFIELDS. * HIGH IN WINDS. * LOW IN ANY SHRA/TSRA OCCURRING AGAIN LATE THURSDAY NIGHT. //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...CHC TSRA. SATURDAY THROUGH MONDAY...VFR TUESDAY...CHC TSRA. MTF/BMD && .MARINE... 155 AM CDT THE WEATHER PATTERN ACROSS THE GREAT LAKES REGION WILL BE A BIT ACTIVE OVER THE NEXT FEW DAYS...WITH SOME PERIODS OF STRONG WINDS IN THE 25 TO 30 KT RANG...ALONG WITH A PERIOD OR TWO OF SHOWERS AND STORMS. A RATHER POTENT EARLY AUTUMN SEASON SURFACE LOW WILL MOVE FROM THE EASTERN DAKOTAS EARLY THIS MORNING TO NEAR JAMES BAY BY EARLY FRIDAY MORNING. THIS SYSTEM WILL CONTINUE TO INDUCE SOME STRONG SOUTHERN WINDS OVER THE LAKE TODAY AND TONIGHT. IT APPEARS THE STRONGEST WINDS UP TO AROUND 30 KT WILL OCCUR THIS EVENING ACROSS THE NORTHERN HALF OF THE LAKE...WITH 20 TO 25 KT SOUTHERLY WINDS OVER THE SOUTHERN HALF OF THE LAKE. THESE STRONG WINDS WILL RESULT IN SMALL CRAFT ADVISORY CONDITIONS INTO THIS EVENING. AS THE LOW SHIFTS OVER THE JAMES BAY FRIDAY MORNING...A TRAILING COLD FRONT WILL SHIFT DOWN THE LAKE DURING THE DAY FRIDAY. WINDS WILL SHIFT NORTHERLY INTO 15 TO 25 KT RANGE LATER FRIDAY AND INTO SATURDAY...BEFORE ABATING LATER SATURDAY AS AN AREA OF SURFACE HIGH PRESSURE BUILDS ACROSS THE SOUTHERN LAKES REGION. THESE NORTHERLY WINDS DOWN THE FETCH OF LAKE MICHIGAN MAY AGAIN RESULT IN SMALL CRAFT ADVISORY CONDITIONS FRIDAY NIGHT AND SATURDAY...WITH WAVES POSSIBLY IN THE 4 TO 7 FT RANGE. THE WEATHER CONDITIONS LOOK TO QUIET DOWN FOR A COUPLE DAYS FOR SUNDAY AND INTO EARLY NEXT WEEK AS SURFACE HIGH PRESSURE DOMINATES ACROSS THE LAKES REGION. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...10 AM THURSDAY TO 10 PM THURSDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1234 AM CDT THU SEP 4 2014 .DISCUSSION... 904 PM CDT ONLY MINOR ADJUSTMENTS TONIGHT. BUT THE GREATEST CHALLENGE RESIDES WITH PRECIP TIMING...COVERAGE. GUIDANCE MEMBERS DIFFERS ON TIMING AND PLACEMENT OF CONVECTION/PRECIP OVERNIGHT. THERE IS A WEAK MID- LVL WAVE SLIDING EAST ACROSS CENTRAL IOWA THAT THE RAP CONTINUES TO LEAN TOWARDS THE FOCAL POINT OVERNIGHT...WITH DEVELOPMENT CLOSER TO MIDNIGHT ALONG THE MISS RIVER. THERE HAS BEEN SOME ISOLATED SHOWERS/THUNDERSTORMS ACROSS SOUTHEAST IOWA SLIDING EAST INTO IL...HOWEVER THE TRENDS HAS BEEN THAT THIS PRECIP WOULD WEAKEN. THE NOSE OF THE LLVL JET AND THETA-E IS LIFTING NORTH...WHICH COUPLED WITH LLVL MOISTURE STEADILY INCREASING WOULD POINT TOWARDS A POTENTIAL FOR INCREASED PRECIP OVERNIGHT OR CLOSER TO 8-12Z. WILL NUDGE POPS UP TO ACCOUNT FOR THIS...WITH THE FOCUS BEING AFT MIDNIGHT AND CLOSER TO DAYBREAK. BEACHLER //PREV DISCUSSION... 252 PM CDT SHORT TERM... FOR THE REMAINDER OF THIS AFTERNOON AND INTO THIS EVENING...QUIET WEATHER CONDITIONS WILL PREVAIL AS SFC HIGH PRESSURE MOVES OFF TO THE EAST AND LOW PRESSURE DEVELOPS OVER THE NORTHERN PLAINS. ALOFT...BROAD UPPER RIDGING EXTENDS ACROSS THE SRN CONUS WITH ZONAL FLOW OVER THE NRN CONUS. WINDS ACROSS THE AREA AT THE SFC HAVE BEEN VERY LIGHT...WHICH HAS ALLOWED A LAKE BREEZE TO FORM...BUT SLIGHTLY STRONGER WINDS ALOFT HAVE KEPT THE LAKE BREEZE BOUNDARY FROM PUSHING INLAND MUCH FARTHER THAN DOWNTOWN CHICAGO. SO...WHILE MUCH OF THE AREA WILL SEE TEMPERATURES TOP OUT IN THE LOWER TO MIDDLE 80S...THE ILLINOIS LAKEFRONT HAS REMAINED MUCH COOLER WITH HIGHS TODAY TOPPING OUT IN THE MIDDLE 70S. A FEW WEAK SHORT WAVES ARE RIPPLING THROUGH THE ZONAL FLOW...GENERATING AREAS OF SHOWERS AND THUNDERSTORMS...BUT NONE ARE CURRENTLY CLOSE TO THE LOCAL AREA. INTO THIS EVENING...THERE WILL BE AN INCREASING CHANCE FOR THUNDERSTORMS AS MOISTURE STREAMS NWD AROUND THE WRN PERIPHERY OF THE SFC HIGH AS SOUTHERLY FLOW DEVELOPS. BY LATE THIS EVENING...ANTICIPATE A STRONG CONVECTIVE COMPLEX TO DEVELOP OVER THE UPPER MISSISSIPPI VALLEY ON THE LEADING EDGE OF A STRONG LOW LEVEL JET WHERE SPC HAS OUTLOOKED A SLIGHT RISK FOR SEVERE THUNDERSTORMS. THE MAIN QUESTION REMAINS AS TO HOW THE CONVECTIVE COMPLEX WILL EVOLVE THROUGH THE EVENING AND OVERNIGHT. THE ANTICIPATION IS THAT THE SYSTEM MAY DEVELOP INTO A BOWING LINE OR SQUALL LINE OVERNIGHT AND PROPAGATE TO THE SOUTHEAST...ACROSS WISCONSIN. THE LATEST HIGH RES MODEL GUIDANCE...INCLUDING THE LOCAL WRF...SUGGEST THAT THE LINE OF THUNDERSTORMS MAY HANG TOGETHER LONG ENOUGH THE REACH NRN/NWRN IL AFTER MIDNIGHT AND INTO THE EARLY MORNING HOURS BEFORE DISSIPATING. HOWEVER...SINCE THERE IS STILL SOME UNCERTAINTY TO THE TIMING AND TRACK OF THE SYSTEM...HAVE KEPT POPS IN THE CHANCE RANGE AND CONFINED THE MENTION OF PCPN TO THE NRN TIER COUNTIES OF IL ALONG THE WISCONSIN BORDER. WHILE THERE IS STILL A CHANCE THAT SOME STRAY SHOWERS OR THUNDERSTORMS COULD LINGER INTO THE MORNING HOURS TOMORROW...GENERALLY EXPECT THAT THE REST OF THE DAY THURSDAY SHOULD BE DRY. THE MAIN CONCERN FOR THURSDAY WILL BE THE TEMPERATURE FORECAST. THE UPPER LEVEL PATTERN WILL BEGIN TO SHOW SOME AMPLIFICATION AS THE UPPER RIDGE BUILDS ACROSS THE MIDWEST AND GREAT LAKES WHILE AN UPPER LOW MOVING EWD FROM THE PAC NORTHWEST TRACKS ACROSS THE SRN CANADIAN PRAIRIES. THE MAIN EFFECT FOR THE LOCAL AREA WILL BE A CONTINUATION OF PUMPING UP LOW LEVEL MOISTURE...WITH SFC DEWPOINT LIKELY CLIMBING INTO THE LOW 70S. THE VARIOUS AND SUNDRY MODELS ARE IN RELATIVELY GOOD AGREEMENT ON BRINGING 850MB TEMPS OF 22-23C ACROSS THE AREA. UNDER FULL SUNSHINE...THIS WOULD IMPLY MAX TEMPS IN THE LOW 90S. HOWEVER...SOME RESIDUAL CLOUD COVER...EVEN PARTIAL CLOUD COVER...COULD LIMIT SLIGHTLY THE POTENTIAL MAXIMUM WARMING...SO...HAVE MAINTAINED THE GOING FORECAST OF MAX TEMPS IN THE UPPER 80S TO SOME AREAS AROUND 90-91F. THIS COMBINATION OF TEMPERATURES AROUND 90F WITH DEWPOINTS IN THE LOW 70S WOULD GENERATE MAX HEAT INDEX VALUES CLOSE TO 100F. SO...WHILE HEAT ADVISORY CRITERIA WILL LIKELY NOT BE MET...IT WILL CERTAINLY BE A HOT AND HUMID DAY...THE LIKES OF WHICH HAS BEEN FEW AND FAR BETWEEN THIS SUMMER. THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL COME THURSDAY NIGHT AND FRIDAY AS A SFC LOW DEVELOPS OVER THE CNTRL PLAINS TRACKS NORTHEAST ACROSS THE UPPER MISSOURI VALLEY AND INTO THE UPPER MISSISSIPPI VALLEY THURSDAY. THIS SFC LOW WILL DRAG A TRAILING COLD FRONT ACROSS THE UPPER MISSISSIPPI VALLEY BY THURSDAY EVENING. THE MODEL GUIDANCE HAS BEEN RELATIVELY CONSISTENT IN ADVERTISING A RELATIVELY STRONG COLD FRONT ASSOCIATED WITH THE DEEPENING UPPER LEVEL LONGWAVE TROUGH DROPPING INTO THE NRN PLAINS. THIS IS SHAPING UP TO BE A RATHER DYNAMIC SYSTEM WITH STRONG UPPER FORCING WITH THE 100KT+ JET ACROSS THE UPPER MISSISSIPPI VALLEY AND GREAT LAKES...A STRONG MID LEVEL TROUGH AND SFC COLD FRONT. ALSO...THE MODELS ARE SHOWING SIGNIFICANT MOISTURE POOLING AHEAD OF THE SFC FRONT WITH PWATS OF 2 INCHES ALONG THE BOUNDARY. WHILE THE STRONGEST UPPER LEVEL FORCING WILL BE WELL NORTH OF THE CWA...AS SPC OUTLOOKS A SLIGHT RISK OVER WISCONSIN AND THE WESTERN GREAT LAKES IN THE DAY 2 OUTLOOK...SO THE GREATEST SEVERE POTENTIAL SHOULD BE TO THE NORTH...THERE WILL STILL BE THE POTENTIAL FOR STRONG THUNDERSTORMS PRODUCING LOCALLY HEAVY RAINFALL. AS THE SYSTEM SHOULD BE QUICKLY PROGRESSIVE...WIDESPREAD FLOODING SHOULD NOT BE A MAJOR CONCERN...BUT LOCALIZED FLOODING OR FLASH FLOODING IS A POSSIBILITY IF ANY TRAINING SETS UP AS INDIVIDUAL CELLS TRACK NEWD WHILE THE LARGER SCALE SYSTEM PROGRESSES EWD. FORECAST CONFIDENCE BEGINS TO DIMINISH INTO LATE FRIDAY NIGHT AND EARLY SATURDAY AND WHEN THE PCPN WILL CLEAR THE CWA. HAVE GENERALLY BEEN FOLLOWING THE TREND OF THE ECMWF WHICH INDICATES SOME LINGERING PCPN OVER THE SERN PORTIONS OF THE CWA INTO SATURDAY MORNING WHILE THE GFS IS A LITTLE SLOW. CURRENTLY FAVOR A FASTER PROGRESSION GIVEN RELATIVELY LOW AMPLITUDE...FAST FLOW ALOFT...SO...WILL GO DRY BY SATURDAY AFTERNOON. FOR THE LONGER TERM...FROM SATURDAY AFTERNOON AND INTO THE MIDDLE OF NEXT WEEK. EXPECT THAT THE REMAINDER OF THE WEEKEND AND EARLY NEXT WEEK SHOULD BE DRY...BUT ON THE COOLER SIDE AS HIGH PRESSURE BUILDS ACROSS THE MIDWEST WHILE A QUICK MOVING LOW SCOOTS ACROSS THE UPPER GREAT LAKES...SETTING UP LIGHT FLOW OFF OF THE LAKE. BY MONDAY NIGHT AND INTO TUESDAY...ANOTHER SYSTEM IS EXPECTED TO DEVELOP OVER THE CNTRL PLAINS...DRAGGING ANOTHER COLD FRONT ACROSS THE AREA...WHICH WILL BRING CHANCES FOR MORE SHOWERS AND THUNDERSTORMS BY TUESDAY AND WEDNESDAY. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * LOW-LEVEL WIND SHEAR THROUGH 12Z-13Z. * CHANCE FOR SCATTERED OR AREA OF TSRA THIS MORNING AFTER DAYBREAK. * GUSTY SSW WINDS THIS AFTERNOON. * SMALL CHANCE FOR SHRA/TSRA AGAIN NEAR DAYBREAK FRIDAY. //DISCUSSION...UPDATED 06Z... A POSSIBLY ACTIVE COUPLE/FEW HOURS OF SOME TSRA MAY OCCUR THIS MORNING AFTER DAYBREAK. FIRST...SOUTHERLY WINDS AT 1500-2500 FT HAVE BEEN OBSERVED ON DOPPLER RADAR AND AIRCRAFT AT 40-45 KT FROM MULTIPLE AIRPORTS ACROSS NORTHERN IL AND EASTERN IA. WHILE THERE IS SURFACE SOUTHERLY FLOW...THE RATE OF INCREASE IN WIND SPEED WITH HEIGHT APPEARS TO BE QUITE SHARP...SO HAVE ADDED LOW-LEVEL WIND SHEAR MENTION INTO THE AREA TAFS. OF LARGER CONCERN IS INCREASING MOISTURE AND INSTABILITY ALOFT BY SUNRISE INTO THE MID- MORNING HOURS. THIS IS IN TANDEM WITH THE PASSAGE OF AN UPPER LEVEL DISTURBANCE. THIS SETUP COULD FAVOR EVOLUTION OF THUNDERSTORMS FROM EASTERN IA AND SOUTHERN WI OVER THE AREA. CONFIDENCE IS LOW ON EXACTLY WHAT COVERAGE WOULD BE...BUT AT THIS TIME WOULD BE SURPRISED TO NOT HAVE AT LEAST ISOLATED SHRA/TSRA OCCURRING IN THE 11Z-16Z WINDOW OVER NORTH CENTRAL/NORTHEAST IL. ANY ACTIVITY SHOULD SEE A QUICK WEAKENING TREND LATER IN THE MORNING AND EARLY AFTERNOON AS IT EVOLVES SOUTHEAST. AGAIN...CONFIDENCE ON THIS IS FAIRLY LOW...BUT WORTH NOTING AT LEAST VCTS IN TAFS...AND CONTINUE THE TSRA MENTION AT ROCKFORD. SOUTH-SOUTHWEST SURFACE WINDS SHOULD BECOME GUSTY BY LATE MORNING OR EARLY AFTERNOON AND PERSIST THROUGH THE AFTERNOON AND POSSIBLY EVEN EARLY EVE. THE WIND DIRECTION MAY OCCASIONALLY BE NEAR 180 DEGREES. OTHERWISE...THE EVENING INTO THE OVERNIGHT SHOULD BE FAIRLY QUIET...WITH A SYSTEM COLD FRONT EXPECTED TO ARRIVE AFTER DAYBREAK FRIDAY...BRINGING SHRA/TSRA CHANCE DURING THE DAY. //ORD AND MDW CONFIDENCE...UPDATED 06Z... * HIGH IN 40-45 KT SSW FLOW AROUND 1500-2500 FT THROUGH DAYBREAK. * MEDIUM IN VCTS OCCURRING...LOW IN WHAT COVERAGE OF STORMS WILL BE AND IF THEY WILL OCCUR OVER THE AIRFIELDS. * HIGH IN WINDS. * LOW IN ANY SHRA/TSRA OCCURRING AGAIN LATE THURSDAY NIGHT. //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...CHC TSRA. SATURDAY THROUGH MONDAY...VFR TUESDAY...CHC TSRA. MTF/BMD && .MARINE... 218 PM CDT STRONG SOUTH TO SOUTHWEST WINDS THURSDAY AND THURSDAY NIGHT WILL BE THE MAIN FOCUS OF THE FORECAST. CURRENTLY...HIGH PRESSURE IS STRETCHED ACROSS THE APPALACHIANS WITH A WEAKER RIDGE AXIS ACROSS LAKE MICHIGAN. LOW PRESSURE IS SPREAD ACROSS THE NORTHERN PLAINS AND WILL CONSOLIDATE AS IT LIFTS NORTHEAST ACROSS NORTHERN MINNESOTA AND INTO WESTERN ONTARIO INTO FRIDAY. THIS WILL BRING A STRENGTHENING PRESSURE GRADIENT ACROSS LAKE MICHIGAN STARTING TONIGHT WHICH WILL BRING AN INCREASING SOUTH WIND. THE STRONGEST WINDS ARE EXPECTED THURSDAY EVENING/NIGHT AS THE LOW DEEPENS AS IT TRACKS EASTWARD ACROSS NORTH CENTRAL ONTARIO. FORTUNATELY WARM AIR WILL BE IN PLACE ACROSS THE LAKE WHICH WILL LIMIT MIXING AND WILL LIKELY KEEP WIND SPEEDS BELOW GALE FORCE. THE STRONGEST WINDS WILL BE ACROSS CENTRAL AND NORTHERN LAKE MICHIGAN WITH SPEEDS TO 30 KT EXPECTED. WINDS WILL STRENGTHEN QUICKLY IN THE FIRST FEW HUNDRED FEET ABOVE THE LAKE SURFACE SO SOME OF THE TALLEST PILOT HOUSES MAY SEE 35-40 KT WINDS WHILE WINDS CLOSER TO THE SURFACE REMAIN NEAR 30 KT. A COOL FRONT WILL CROSS THE LAKE FRIDAY MORNING TURNING WINDS NORTHERLY BUT THE GRADIENT WILL QUICKLY SLACKEN ALLOWING SPEEDS TO DIMINISH. WITH SOUTH TO SOUTHWEST WINDS BLOWING OFFSHORE ACROSS THE IL/IN NEARSHORE WATERS THURSDAY/THURSDAY NIGHT BETTER MIXING WILL OCCUR OVER THE NEARSHORE WATERS. EXPECT GUSTS TO AROUND 25 KT THURSDAY AFTERNOON WITH PEAK MIXING BUT THEN EASE AFTER DARK THURSDAY EVENING. WILL HOIST A SMALL CRAFT ADVISORY FROM LATE THURSDAY MORNING THROUGH THE EARLY EVENING. HIGH PRESSURE WILL SETTLE SOUTHWARD INTO THE CENTRAL PLAINS KEEPING A DECENT PRESSURE GRADIENT ACROSS SOUTHERN LAKE MICHIGAN FRIDAY AFTERNOON THROUGH SATURDAY. SPEEDS REMAIN JUST BELOW SMALL CRAFT CRITERIA BUT THE SUSTAINED PERIOD OF LONGER FETCH MAY BRING WAVES TO SMALL CRAFT CRITERIA LATE FRIDAY NIGHT THROUGH THE DAY SATURDAY. HIGH PRESSURE RIDGE WILL SPREAD ACROSS THE ENTIRE LAKE LATER SATURDAY ALLOWING WINDS TO DIMINISH INTO SATURDAY NIGHT. THE HIGH WILL GRADUALLY WORK EASTWARD THROUGH MONDAY KEEPING WINDS LIGHT OVERALL WITH A TENDENCY TO TURN ONSHORE SUNDAY AND MONDAY AFTERNOON. A STEADIER SOUTHERLY WIND IS EXPECTED TO RETURN INTO TUESDAY. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...SMALL CRAFT ADVISORY...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744- LMZ745...10 AM THURSDAY TO 10 PM THURSDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
206 PM EDT THU SEP 4 2014 .SYNOPSIS... ISSUED AT 1226 PM EDT THU SEP 4 2014 A WARM FRONT WILL MOVE NORTH TODAY AND BRING A SMALL CHANCE FOR SHOWERS AND THUNDERSTORMS TO NORTHERN INDIANA AND SOUTHWEST LOWER MICHIGAN THROUGH EARLY AFTERNOON. ELSEWHERE IT WILL BE DRY WITH PARTLY SUNNY SKIES. HIGHS WILL BE IN THE MID TO UPPER 80S. THERE WILL BE A SLIGHT CHANCE FOR A THUNDERSTORM TONIGHT...MAINLY AFTER MIDNIGHT AND NORTH OF HIGHWAY 30. IT WILL REMAIN VERY MUGGY AND WARM OVERNIGHT WITH LOWS IN THE UPPER 60S TO LOWER 70S. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 403 AM EDT THU SEP 4 2014 IMMEDIATE CONCERN IN THE SHORT TERM PERIOD IS HANDLING OF UPSTREAM CONVECTION THAT HAS FIRED OVERNIGHT. LOW LEVEL JET NOSING INTO THETA E GRADIENT HAS ALLOWED CONVECTION TO DEVELOP OVER IA AND IT CONTINUES TO RIDE NOSE OF THIS LLJ AND TRACK EAST. WEAK CONVECTION HAS TRIED TO FIRE AHEAD OF THIS AREA OVER EASTERN IL AND SOUTHERN LAKE MICHIGAN BUT IT HAS STRUGGLED SO FAR WITH DRIER AIR STILL IN PLACE. AS THETA E RIDGE SHIFTS EAST EARLY THIS MORNING EXPECT CONVECTIVE COMPLEX TO CONTINUE ITS TREK EAST AS WELL. AS DAYTIME HEATING COMMENCES AND LLJ RELAXES EXPECT THIS CONVECTION TO DISSIPATE THROUGH THE MORNING HOURS. HIRES MODELS HAVE BEEN TRYING TO HANDLE THIS ALONG WITH LARGER COMPLEX FURTHER NORTH BUT HAVE BEEN STRUGGLING WITH EVOLUTION DETAILS. LATEST RUC AND HRRR HAVE PICKED UP ON IA COMPLEX BUT SEEM UNDERDONE AND HAVE THIS DISSIPATING BEFORE REACHING THE AREA. EXPECT NEXT FEW RUNS TO BE MORE AGGRESSIVE BASED ON LATEST RADAR/SATELLITE/LIGHTNING TRENDS. 30 TO 40 KNOT LLJ FEEDING THIS SEEMS TO BE KEEPING IT ON AN EASTWARD TRACK DESPITE 850-300MB THICKNESS LINES SHOWING A POSSIBLE MOVEMENT TO THE SOUTHEAST. WILL HAVE TO MONITOR TRENDS NEXT FEW HOURS CLOSELY BUT FOR NOW HAVE EXPANDED POPS AND INCREASED SKY COVER THIS MORNING TO COVER MOST OF WESTERN AND NORTHERN THIRD OF CWA. WILL TAPER POPS OFF BY AFTERNOON WITH SKIES BECOMING PARTLY CLOUDY TO MOSTLY SUNNY. THIS POSES THE NEXT PROBLEM WITH HIGH TEMPS FOR TODAY. SOUNDINGS SUGGEST MIXING TO AROUND 900MB WHICH WILL YIELD HIGHS IN THE MID TO UPPER 80S. OBVIOUSLY NOW LOOKING AT SLOWER WARMING TRENDS THIS MORNING WITH SATELLITE SHOWING INCREASED CLOUD DEVELOPMENT. STILL EXPECT A RAPID WARMUP LATER IN THE DAY ONCE CLOUDS ERODE SO STAYED WITH MID 80S EXCEPT IN FAR SOUTHWEST WHERE UPPER 80S STILL LIKELY. MODEL SOUNDINGS SHOW DECENT CAPPING INVERSION THIS AFTERNOON DESPITE MUCAPES CLIMBING TO BETWEEN 1K AND 2K J/KG. DEWPOINTS WILL CREEP INTO THE UPPER 60S MAKING IT FEEL QUITE HUMID. NOT MUCH FOCUS FOR CONVECTION TONIGHT BUT MOISTURE RICH AIR WILL BE IN PLACE WITH ELEVATED INSTABILITY SO IT WILL NOT TAKE MUCH TO SPARK AN ISOLATED TSRA. WILL KEEP SLIGHT CHANCE POPS ACROSS NORTHERN TWO THIRDS OF AREA WELL AHEAD OF MAIN COLD FRONT. && .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 403 AM EDT THU SEP 4 2014 MAIN FOCUS FRIDAY-FRIDAY NIGHT REMAINS CONVECTIVE CHANCES/COVERAGE AS TRAILING COLD FRONT FROM POTENT SHORTWAVE TRACKING NE TO JAMES BAY SAGS SOUTHEAST INTO A MOIST/UNSTABLE AIRMASS. MUCH OF FRIDAY MORNING-EARLY AFTERNOON SHOULD REMAIN MAINLY DRY IN CAPPED WARM SECTOR (850 MB TEMPS 21C)...ALTHOUGH CANNOT COMPLETELY RULE OUT CONVECTIVE REMNANTS/OUTFLOW SURVIVING INTO NORTHERN/WESTERN ZONES IN LOW LEVEL THETA-E ADVECTION REGIME. EXPECTED STRONG DIURNAL HEATING AND POOLED 70F DEWPOINTS NEAR FRONT...CONCURRENT WITH OVERSPREAD OF WEAK 20-30M 5H HEIGHT FALLS...SHOULD BE SUFFICIENT TO BREAK CAP/FIRE CONVECTION ALONG THE SAGGING FRONTAL ZONE BY MID-LATE AFTERNOON. COVERAGE REMAINS QUESTIONABLE HOWEVER WITH BETTER MID LEVEL HEIGHT FALLS/FORCING INITIALLY CONFINED NORTH. THIS REMAINS THE PRIMARY REASON FOR HOLDING SHY OF LIKELY POPS AT THIS FCST RANGE. POST FRONTAL LAG OF STRONGER MID LEVEL FLOW/DEEP SHEAR AND WHAT SHOULD BE A VERY UNSTABLE ENVIRONMENT (MLCAPE 2500 J/KG PLUS) HINTS AT A LOW END SEVERE THREAT (ISOLATED) WITH SHORT-LIVED UPDRAFTS CAPABLE OF PRODUCING STRONG OUTFLOWS/DOWNBURSTS. FAIR AMOUNT OF CAPE IN THE M10-M30 LAYER ALSO SUGGESTIVE OF A LOW END HAIL THREAT AS WELL. OVERSPREAD OF BETTER HEIGHT FALLS/RIGHT ENTRANCE UPPER JET SUPPORT WILL TIGHTEN/DEEPEN THE FRONTAL ZONE AS IT DROPS THROUGH SOUTHERN/EASTERN ZONES FRIDAY NIGHT...WITH AMPLE MOISTURE AND POTENTIAL FOR LOWER AMPLITUDE SHORTWAVE ENERGY TO PROPAGATE THROUGH IN SW FLOW PROBABLY ENOUGH TO HELP GENERATE ADDITIONAL RAIN/THUNDER ALONG FRONTAL SLOPE. WITH THAT SAID...ONCE AGAIN HELD SHY OF LIKELY POPS GIVEN NORMAL UNCERTAINTIES WITH CONVECTION AND RECENT MAINLY DRY FRONTAL PASSAGES IN SIMILAR SETUPS. A FEW SHOWERS/LOW CLOUDS MAY LINGER INTO SATURDAY MORNING ACROSS SOUTHERN/EASTERN ZONES...WITH THE REST OF THE WEEKEND INTO EARLY NEXT WEEK MUCH COOLER/DRIER AS BROAD HIGH PRESSURE BUILDS IN WAKE OF FRONT/SHORTWAVE TROUGH. RETURN FLOW TIMED WITH THE NEXT ROUND OF HEIGHT FALLS ON THE BACKSIDE OF THIS AREA OF HIGH PRESSURE BRINGS SHOWER/STORM CHANCES BACK INTO THE FORECAST BY THE MIDDLE OF NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 152 PM EDT THU SEP 4 2014 THERE WAS A VERY TIGHT SURFACE THETA E GRADIENT OVER NRN IL...BUT WELL TO THE SOUTHWEST OF CHICAGO. SPC MESOANALYSIS GRAPHICS AND EARLY MORNING SOUNDINGS INDICATE INCREASINGLY STABLE CONDITIONS FURTHER EAST INTO INDIANA...WITH ONGOING CONVECTIVE ACTIVITY HAVING A HARD TIME SUSTAINING ITSELF ACROSS NRN INDIANA. GIVEN THIS ENVIRONMENT... THE LATEST RADAR TRENDS...AND SOME HIGH RESOLUTION NCEP MODELS THAT ARE FINALLY STARTING TO HANDLE THIS SCENARIO...KEPT THE TAFS DRY. EXPECT THE FRONT WILL DROP SOUTHEAST INTO THE AREA FRIDAY AFTERNOON...WITH STORMS DEVELOPING JUST AFTER THE END OF THE TAF PERIOD. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...CEO SHORT TERM...LASHLEY LONG TERM...STEINWEDEL AVIATION...SKIPPER VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1227 PM EDT THU SEP 4 2014 .SYNOPSIS... ISSUED AT 1226 PM EDT THU SEP 4 2014 A WARM FRONT WILL MOVE NORTH TODAY AND BRING A SMALL CHANCE FOR SHOWERS AND THUNDERSTORMS TO NORTHERN INDIANA AND SOUTHWEST LOWER MICHIGAN THROUGH EARLY AFTERNOON. ELSEWHERE IT WILL BE DRY WITH PARTLY SUNNY SKIES. HIGHS WILL BE IN THE MID TO UPPER 80S. THERE WILL BE A SLIGHT CHANCE FOR A THUNDERSTORM TONIGHT...MAINLY AFTER MIDNIGHT AND NORTH OF HIGHWAY 30. IT WILL REMAIN VERY MUGGY AND WARM OVERNIGHT WITH LOWS IN THE UPPER 60S TO LOWER 70S. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 403 AM EDT THU SEP 4 2014 IMMEDIATE CONCERN IN THE SHORT TERM PERIOD IS HANDLING OF UPSTREAM CONVECTION THAT HAS FIRED OVERNIGHT. LOW LEVEL JET NOSING INTO THETA E GRADIENT HAS ALLOWED CONVECTION TO DEVELOP OVER IA AND IT CONTINUES TO RIDE NOSE OF THIS LLJ AND TRACK EAST. WEAK CONVECTION HAS TRIED TO FIRE AHEAD OF THIS AREA OVER EASTERN IL AND SOUTHERN LAKE MICHIGAN BUT IT HAS STRUGGLED SO FAR WITH DRIER AIR STILL IN PLACE. AS THETA E RIDGE SHIFTS EAST EARLY THIS MORNING EXPECT CONVECTIVE COMPLEX TO CONTINUE ITS TREK EAST AS WELL. AS DAYTIME HEATING COMMENCES AND LLJ RELAXES EXPECT THIS CONVECTION TO DISSIPATE THROUGH THE MORNING HOURS. HIRES MODELS HAVE BEEN TRYING TO HANDLE THIS ALONG WITH LARGER COMPLEX FURTHER NORTH BUT HAVE BEEN STRUGGLING WITH EVOLUTION DETAILS. LATEST RUC AND HRRR HAVE PICKED UP ON IA COMPLEX BUT SEEM UNDERDONE AND HAVE THIS DISSIPATING BEFORE REACHING THE AREA. EXPECT NEXT FEW RUNS TO BE MORE AGGRESSIVE BASED ON LATEST RADAR/SATELLITE/LIGHTNING TRENDS. 30 TO 40 KNOT LLJ FEEDING THIS SEEMS TO BE KEEPING IT ON AN EASTWARD TRACK DESPITE 850-300MB THICKNESS LINES SHOWING A POSSIBLE MOVEMENT TO THE SOUTHEAST. WILL HAVE TO MONITOR TRENDS NEXT FEW HOURS CLOSELY BUT FOR NOW HAVE EXPANDED POPS AND INCREASED SKY COVER THIS MORNING TO COVER MOST OF WESTERN AND NORTHERN THIRD OF CWA. WILL TAPER POPS OFF BY AFTERNOON WITH SKIES BECOMING PARTLY CLOUDY TO MOSTLY SUNNY. THIS POSES THE NEXT PROBLEM WITH HIGH TEMPS FOR TODAY. SOUNDINGS SUGGEST MIXING TO AROUND 900MB WHICH WILL YIELD HIGHS IN THE MID TO UPPER 80S. OBVIOUSLY NOW LOOKING AT SLOWER WARMING TRENDS THIS MORNING WITH SATELLITE SHOWING INCREASED CLOUD DEVELOPMENT. STILL EXPECT A RAPID WARMUP LATER IN THE DAY ONCE CLOUDS ERODE SO STAYED WITH MID 80S EXCEPT IN FAR SOUTHWEST WHERE UPPER 80S STILL LIKELY. MODEL SOUNDINGS SHOW DECENT CAPPING INVERSION THIS AFTERNOON DESPITE MUCAPES CLIMBING TO BETWEEN 1K AND 2K J/KG. DEWPOINTS WILL CREEP INTO THE UPPER 60S MAKING IT FEEL QUITE HUMID. NOT MUCH FOCUS FOR CONVECTION TONIGHT BUT MOISTURE RICH AIR WILL BE IN PLACE WITH ELEVATED INSTABILITY SO IT WILL NOT TAKE MUCH TO SPARK AN ISOLATED TSRA. WILL KEEP SLIGHT CHANCE POPS ACROSS NORTHERN TWO THIRDS OF AREA WELL AHEAD OF MAIN COLD FRONT. && .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 403 AM EDT THU SEP 4 2014 MAIN FOCUS FRIDAY-FRIDAY NIGHT REMAINS CONVECTIVE CHANCES/COVERAGE AS TRAILING COLD FRONT FROM POTENT SHORTWAVE TRACKING NE TO JAMES BAY SAGS SOUTHEAST INTO A MOIST/UNSTABLE AIRMASS. MUCH OF FRIDAY MORNING-EARLY AFTERNOON SHOULD REMAIN MAINLY DRY IN CAPPED WARM SECTOR (850 MB TEMPS 21C)...ALTHOUGH CANNOT COMPLETELY RULE OUT CONVECTIVE REMNANTS/OUTFLOW SURVIVING INTO NORTHERN/WESTERN ZONES IN LOW LEVEL THETA-E ADVECTION REGIME. EXPECTED STRONG DIURNAL HEATING AND POOLED 70F DEWPOINTS NEAR FRONT...CONCURRENT WITH OVERSPREAD OF WEAK 20-30M 5H HEIGHT FALLS...SHOULD BE SUFFICIENT TO BREAK CAP/FIRE CONVECTION ALONG THE SAGGING FRONTAL ZONE BY MID-LATE AFTERNOON. COVERAGE REMAINS QUESTIONABLE HOWEVER WITH BETTER MID LEVEL HEIGHT FALLS/FORCING INITIALLY CONFINED NORTH. THIS REMAINS THE PRIMARY REASON FOR HOLDING SHY OF LIKELY POPS AT THIS FCST RANGE. POST FRONTAL LAG OF STRONGER MID LEVEL FLOW/DEEP SHEAR AND WHAT SHOULD BE A VERY UNSTABLE ENVIRONMENT (MLCAPE 2500 J/KG PLUS) HINTS AT A LOW END SEVERE THREAT (ISOLATED) WITH SHORT-LIVED UPDRAFTS CAPABLE OF PRODUCING STRONG OUTFLOWS/DOWNBURSTS. FAIR AMOUNT OF CAPE IN THE M10-M30 LAYER ALSO SUGGESTIVE OF A LOW END HAIL THREAT AS WELL. OVERSPREAD OF BETTER HEIGHT FALLS/RIGHT ENTRANCE UPPER JET SUPPORT WILL TIGHTEN/DEEPEN THE FRONTAL ZONE AS IT DROPS THROUGH SOUTHERN/EASTERN ZONES FRIDAY NIGHT...WITH AMPLE MOISTURE AND POTENTIAL FOR LOWER AMPLITUDE SHORTWAVE ENERGY TO PROPAGATE THROUGH IN SW FLOW PROBABLY ENOUGH TO HELP GENERATE ADDITIONAL RAIN/THUNDER ALONG FRONTAL SLOPE. WITH THAT SAID...ONCE AGAIN HELD SHY OF LIKELY POPS GIVEN NORMAL UNCERTAINTIES WITH CONVECTION AND RECENT MAINLY DRY FRONTAL PASSAGES IN SIMILAR SETUPS. A FEW SHOWERS/LOW CLOUDS MAY LINGER INTO SATURDAY MORNING ACROSS SOUTHERN/EASTERN ZONES...WITH THE REST OF THE WEEKEND INTO EARLY NEXT WEEK MUCH COOLER/DRIER AS BROAD HIGH PRESSURE BUILDS IN WAKE OF FRONT/SHORTWAVE TROUGH. RETURN FLOW TIMED WITH THE NEXT ROUND OF HEIGHT FALLS ON THE BACKSIDE OF THIS AREA OF HIGH PRESSURE BRINGS SHOWER/STORM CHANCES BACK INTO THE FORECAST BY THE MIDDLE OF NEXT WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 740 AM EDT THU SEP 4 2014 TSRA COMPLEX EXTENDING FROM WRN LWR MI SWWD INTO WEST CENTRAL IL MAKING SLOW EASTWARD PROGRESS EARLY THIS MORNING. EXPECT BACKING/WKNG LLJ THIS MORNING WILL RESULT IN A MORE NEWD TREND WITH MOVEMENT OF MCS AS WELL AS A DIMINISHING TREND. WOULDN`T TOTALLY RULE OUT A SHRA/TSRA REACHING KSBN THROUGH 14-15Z BUT THREAT REMAINS LOW ENOUGH NOT TO INCLUDE TEMPO GROUP. OTRWS VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT BOTH TERMINALS. AGAIN TONIGHT THERE IS SOME POTENTIAL FOR TSRA AS LOW LEVEL THETA-E ADVECTION/CONVERGENCE OVERSPREAD THE AREA BUT ATTM CONFIDENCE TOO LOW TO INCLUDE IN TAFS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...CEO SHORT TERM...LASHLEY LONG TERM...STEINWEDEL AVIATION...JT VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
741 AM EDT THU SEP 4 2014 .SYNOPSIS... ISSUED AT 403 AM EDT THU SEP 4 2014 A WARM FRONT WILL MOVE NORTH TODAY AND BRING A SMALL CHANCE FOR SHOWERS AND THUNDERSTORMS TO NORTHERN INDIANA AND SOUTHWEST LOWER MICHIGAN THROUGH EARLY AFTERNOON. SKIES WILL BE PARTLY TO MOSTLY CLOUDY THIS MORNING FOLLOWED BY CLEARING THIS AFTERNOON. IT WILL BECOME MORE HUMID AND WARMER BY THIS AFTERNOON WITH HIGHS REACHING THE MIDDLE TO UPPER 80S. THERE WILL BE A SLIGHT CHANCE FOR A THUNDERSTORM TONIGHT...MAINLY AFTER MIDNIGHT AND NORTH OF HIGHWAY 30. IT WILL REMAIN VERY MUGGY AND WARM OVERNIGHT WITH LOWS IN THE UPPER 60S TO LOWER 70S. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 403 AM EDT THU SEP 4 2014 IMMEDIATE CONCERN IN THE SHORT TERM PERIOD IS HANDLING OF UPSTREAM CONVECTION THAT HAS FIRED OVERNIGHT. LOW LEVEL JET NOSING INTO THETA E GRADIENT HAS ALLOWED CONVECTION TO DEVELOP OVER IA AND IT CONTINUES TO RIDE NOSE OF THIS LLJ AND TRACK EAST. WEAK CONVECTION HAS TRIED TO FIRE AHEAD OF THIS AREA OVER EASTERN IL AND SOUTHERN LAKE MICHIGAN BUT IT HAS STRUGGLED SO FAR WITH DRIER AIR STILL IN PLACE. AS THETA E RIDGE SHIFTS EAST EARLY THIS MORNING EXPECT CONVECTIVE COMPLEX TO CONTINUE ITS TREK EAST AS WELL. AS DAYTIME HEATING COMMENCES AND LLJ RELAXES EXPECT THIS CONVECTION TO DISSIPATE THROUGH THE MORNING HOURS. HIRES MODELS HAVE BEEN TRYING TO HANDLE THIS ALONG WITH LARGER COMPLEX FURTHER NORTH BUT HAVE BEEN STRUGGLING WITH EVOLUTION DETAILS. LATEST RUC AND HRRR HAVE PICKED UP ON IA COMPLEX BUT SEEM UNDERDONE AND HAVE THIS DISSIPATING BEFORE REACHING THE AREA. EXPECT NEXT FEW RUNS TO BE MORE AGGRESSIVE BASED ON LATEST RADAR/SATELLITE/LIGHTNING TRENDS. 30 TO 40 KNOT LLJ FEEDING THIS SEEMS TO BE KEEPING IT ON AN EASTWARD TRACK DESPITE 850-300MB THICKNESS LINES SHOWING A POSSIBLE MOVEMENT TO THE SOUTHEAST. WILL HAVE TO MONITOR TRENDS NEXT FEW HOURS CLOSELY BUT FOR NOW HAVE EXPANDED POPS AND INCREASED SKY COVER THIS MORNING TO COVER MOST OF WESTERN AND NORTHERN THIRD OF CWA. WILL TAPER POPS OFF BY AFTERNOON WITH SKIES BECOMING PARTLY CLOUDY TO MOSTLY SUNNY. THIS POSES THE NEXT PROBLEM WITH HIGH TEMPS FOR TODAY. SOUNDINGS SUGGEST MIXING TO AROUND 900MB WHICH WILL YIELD HIGHS IN THE MID TO UPPER 80S. OBVIOUSLY NOW LOOKING AT SLOWER WARMING TRENDS THIS MORNING WITH SATELLITE SHOWING INCREASED CLOUD DEVELOPMENT. STILL EXPECT A RAPID WARMUP LATER IN THE DAY ONCE CLOUDS ERODE SO STAYED WITH MID 80S EXCEPT IN FAR SOUTHWEST WHERE UPPER 80S STILL LIKELY. MODEL SOUNDINGS SHOW DECENT CAPPING INVERSION THIS AFTERNOON DESPITE MUCAPES CLIMBING TO BETWEEN 1K AND 2K J/KG. DEWPOINTS WILL CREEP INTO THE UPPER 60S MAKING IT FEEL QUITE HUMID. NOT MUCH FOCUS FOR CONVECTION TONIGHT BUT MOISTURE RICH AIR WILL BE IN PLACE WITH ELEVATED INSTABILITY SO IT WILL NOT TAKE MUCH TO SPARK AN ISOLATED TSRA. WILL KEEP SLIGHT CHANCE POPS ACROSS NORTHERN TWO THIRDS OF AREA WELL AHEAD OF MAIN COLD FRONT. && .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 403 AM EDT THU SEP 4 2014 MAIN FOCUS FRIDAY-FRIDAY NIGHT REMAINS CONVECTIVE CHANCES/COVERAGE AS TRAILING COLD FRONT FROM POTENT SHORTWAVE TRACKING NE TO JAMES BAY SAGS SOUTHEAST INTO A MOIST/UNSTABLE AIRMASS. MUCH OF FRIDAY MORNING-EARLY AFTERNOON SHOULD REMAIN MAINLY DRY IN CAPPED WARM SECTOR (850 MB TEMPS 21C)...ALTHOUGH CANNOT COMPLETELY RULE OUT CONVECTIVE REMNANTS/OUTFLOW SURVIVING INTO NORTHERN/WESTERN ZONES IN LOW LEVEL THETA-E ADVECTION REGIME. EXPECTED STRONG DIURNAL HEATING AND POOLED 70F DEWPOINTS NEAR FRONT...CONCURRENT WITH OVERSPREAD OF WEAK 20-30M 5H HEIGHT FALLS...SHOULD BE SUFFICIENT TO BREAK CAP/FIRE CONVECTION ALONG THE SAGGING FRONTAL ZONE BY MID-LATE AFTERNOON. COVERAGE REMAINS QUESTIONABLE HOWEVER WITH BETTER MID LEVEL HEIGHT FALLS/FORCING INITIALLY CONFINED NORTH. THIS REMAINS THE PRIMARY REASON FOR HOLDING SHY OF LIKELY POPS AT THIS FCST RANGE. POST FRONTAL LAG OF STRONGER MID LEVEL FLOW/DEEP SHEAR AND WHAT SHOULD BE A VERY UNSTABLE ENVIRONMENT (MLCAPE 2500 J/KG PLUS) HINTS AT A LOW END SEVERE THREAT (ISOLATED) WITH SHORT-LIVED UPDRAFTS CAPABLE OF PRODUCING STRONG OUTFLOWS/DOWNBURSTS. FAIR AMOUNT OF CAPE IN THE M10-M30 LAYER ALSO SUGGESTIVE OF A LOW END HAIL THREAT AS WELL. OVERSPREAD OF BETTER HEIGHT FALLS/RIGHT ENTRANCE UPPER JET SUPPORT WILL TIGHTEN/DEEPEN THE FRONTAL ZONE AS IT DROPS THROUGH SOUTHERN/EASTERN ZONES FRIDAY NIGHT...WITH AMPLE MOISTURE AND POTENTIAL FOR LOWER AMPLITUDE SHORTWAVE ENERGY TO PROPAGATE THROUGH IN SW FLOW PROBABLY ENOUGH TO HELP GENERATE ADDITIONAL RAIN/THUNDER ALONG FRONTAL SLOPE. WITH THAT SAID...ONCE AGAIN HELD SHY OF LIKELY POPS GIVEN NORMAL UNCERTAINTIES WITH CONVECTION AND RECENT MAINLY DRY FRONTAL PASSAGES IN SIMILAR SETUPS. A FEW SHOWERS/LOW CLOUDS MAY LINGER INTO SATURDAY MORNING ACROSS SOUTHERN/EASTERN ZONES...WITH THE REST OF THE WEEKEND INTO EARLY NEXT WEEK MUCH COOLER/DRIER AS BROAD HIGH PRESSURE BUILDS IN WAKE OF FRONT/SHORTWAVE TROUGH. RETURN FLOW TIMED WITH THE NEXT ROUND OF HEIGHT FALLS ON THE BACKSIDE OF THIS AREA OF HIGH PRESSURE BRINGS SHOWER/STORM CHANCES BACK INTO THE FORECAST BY THE MIDDLE OF NEXT WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 740 AM EDT THU SEP 4 2014 TSRA COMPLEX EXTENDING FROM WRN LWR MI SWWD INTO WEST CENTRAL IL MAKING SLOW EASTWARD PROGRESS EARLY THIS MORNING. EXPECT BACKING/WKNG LLJ THIS MORNING WILL RESULT IN A MORE NEWD TREND WITH MOVEMENT OF MCS AS WELL AS A DIMINISHING TREND. WOULDN`T TOTALLY RULE OUT A SHRA/TSRA REACHING KSBN THROUGH 14-15Z BUT THREAT REMAINS LOW ENOUGH NOT TO INCLUDE TEMPO GROUP. OTRWS VFR CONDITIONS SHOULD PREVAIL THROUGH THE PERIOD AT BOTH TERMINALS. AGAIN TONIGHT THERE IS SOME POTENTIAL FOR TSRA AS LOW LEVEL THETA-E ADVECTION/CONVERGENCE OVERSPREAD THE AREA BUT ATTM CONFIDENCE TOO LOW TO INCLUDE IN TAFS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...LASHLEY SHORT TERM...LASHLEY LONG TERM...STEINWEDEL AVIATION...JT VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
412 AM EDT THU SEP 4 2014 .SYNOPSIS... ISSUED AT 403 AM EDT THU SEP 4 2014 A WARM FRONT WILL MOVE NORTH TODAY AND BRING A SMALL CHANCE FOR SHOWERS AND THUNDERSTORMS TO NORTHERN INDIANA AND SOUTHWEST LOWER MICHIGAN THROUGH EARLY AFTERNOON. SKIES WILL BE PARTLY TO MOSTLY CLOUDY THIS MORNING FOLLOWED BY CLEARING THIS AFTERNOON. IT WILL BECOME MORE HUMID AND WARMER BY THIS AFTERNOON WITH HIGHS REACHING THE MIDDLE TO UPPER 80S. THERE WILL BE A SLIGHT CHANCE FOR A THUNDERSTORM TONIGHT...MAINLY AFTER MIDNIGHT AND NORTH OF HIGHWAY 30. IT WILL REMAIN VERY MUGGY AND WARM OVERNIGHT WITH LOWS IN THE UPPER 60S TO LOWER 70S. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 403 AM EDT THU SEP 4 2014 IMMEDIATE CONCERN IN THE SHORT TERM PERIOD IS HANDLING OF UPSTREAM CONVECTION THAT HAS FIRED OVERNIGHT. LOW LEVEL JET NOSING INTO THETA E GRADIENT HAS ALLOWED CONVECTION TO DEVELOP OVER IA AND IT CONTINUES TO RIDE NOSE OF THIS LLJ AND TRACK EAST. WEAK CONVECTION HAS TRIED TO FIRE AHEAD OF THIS AREA OVER EASTERN IL AND SOUTHERN LAKE MICHIGAN BUT IT HAS STRUGGLED SO FAR WITH DRIER AIR STILL IN PLACE. AS THETA E RIDGE SHIFTS EAST EARLY THIS MORNING EXPECT CONVECTIVE COMPLEX TO CONTINUE ITS TREK EAST AS WELL. AS DAYTIME HEATING COMMENCES AND LLJ RELAXES EXPECT THIS CONVECTION TO DISSIPATE THROUGH THE MORNING HOURS. HIRES MODELS HAVE BEEN TRYING TO HANDLE THIS ALONG WITH LARGER COMPLEX FURTHER NORTH BUT HAVE BEEN STRUGGLING WITH EVOLUTION DETAILS. LATEST RUC AND HRRR HAVE PICKED UP ON IA COMPLEX BUT SEEM UNDERDONE AND HAVE THIS DISSIPATING BEFORE REACHING THE AREA. EXPECT NEXT FEW RUNS TO BE MORE AGGRESSIVE BASED ON LATEST RADAR/SATELLITE/LIGHTNING TRENDS. 30 TO 40 KNOT LLJ FEEDING THIS SEEMS TO BE KEEPING IT ON AN EASTWARD TRACK DESPITE 850-300MB THICKNESS LINES SHOWING A POSSIBLE MOVEMENT TO THE SOUTHEAST. WILL HAVE TO MONITOR TRENDS NEXT FEW HOURS CLOSELY BUT FOR NOW HAVE EXPANDED POPS AND INCREASED SKY COVER THIS MORNING TO COVER MOST OF WESTERN AND NORTHERN THIRD OF CWA. WILL TAPER POPS OFF BY AFTERNOON WITH SKIES BECOMING PARTLY CLOUDY TO MOSTLY SUNNY. THIS POSES THE NEXT PROBLEM WITH HIGH TEMPS FOR TODAY. SOUNDINGS SUGGEST MIXING TO AROUND 900MB WHICH WILL YIELD HIGHS IN THE MID TO UPPER 80S. OBVIOUSLY NOW LOOKING AT SLOWER WARMING TRENDS THIS MORNING WITH SATELLITE SHOWING INCREASED CLOUD DEVELOPMENT. STILL EXPECT A RAPID WARMUP LATER IN THE DAY ONCE CLOUDS ERODE SO STAYED WITH MID 80S EXCEPT IN FAR SOUTHWEST WHERE UPPER 80S STILL LIKELY. MODEL SOUNDINGS SHOW DECENT CAPPING INVERSION THIS AFTERNOON DESPITE MUCAPES CLIMBING TO BETWEEN 1K AND 2K J/KG. DEWPOINTS WILL CREEP INTO THE UPPER 60S MAKING IT FEEL QUITE HUMID. NOT MUCH FOCUS FOR CONVECTION TONIGHT BUT MOISTURE RICH AIR WILL BE IN PLACE WITH ELEVATED INSTABILITY SO IT WILL NOT TAKE MUCH TO SPARK AN ISOLATED TSRA. WILL KEEP SLIGHT CHANCE POPS ACROSS NORTHERN TWO THIRDS OF AREA WELL AHEAD OF MAIN COLD FRONT. && .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 403 AM EDT THU SEP 4 2014 MAIN FOCUS FRIDAY-FRIDAY NIGHT REMAINS CONVECTIVE CHANCES/COVERAGE AS TRAILING COLD FRONT FROM POTENT SHORTWAVE TRACKING NE TO JAMES BAY SAGS SOUTHEAST INTO A MOIST/UNSTABLE AIRMASS. MUCH OF FRIDAY MORNING-EARLY AFTERNOON SHOULD REMAIN MAINLY DRY IN CAPPED WARM SECTOR (850 MB TEMPS 21C)...ALTHOUGH CANNOT COMPLETELY RULE OUT CONVECTIVE REMNANTS/OUTFLOW SURVIVING INTO NORTHERN/WESTERN ZONES IN LOW LEVEL THETA-E ADVECTION REGIME. EXPECTED STRONG DIURNAL HEATING AND POOLED 70F DEWPOINTS NEAR FRONT...CONCURRENT WITH OVERSPREAD OF WEAK 20-30M 5H HEIGHT FALLS...SHOULD BE SUFFICIENT TO BREAK CAP/FIRE CONVECTION ALONG THE SAGGING FRONTAL ZONE BY MID-LATE AFTERNOON. COVERAGE REMAINS QUESTIONABLE HOWEVER WITH BETTER MID LEVEL HEIGHT FALLS/FORCING INITIALLY CONFINED NORTH. THIS REMAINS THE PRIMARY REASON FOR HOLDING SHY OF LIKELY POPS AT THIS FCST RANGE. POST FRONTAL LAG OF STRONGER MID LEVEL FLOW/DEEP SHEAR AND WHAT SHOULD BE A VERY UNSTABLE ENVIRONMENT (MLCAPE 2500 J/KG PLUS) HINTS AT A LOW END SEVERE THREAT (ISOLATED) WITH SHORT-LIVED UPDRAFTS CAPABLE OF PRODUCING STRONG OUTFLOWS/DOWNBURSTS. FAIR AMOUNT OF CAPE IN THE M10-M30 LAYER ALSO SUGGESTIVE OF A LOW END HAIL THREAT AS WELL. OVERSPREAD OF BETTER HEIGHT FALLS/RIGHT ENTRANCE UPPER JET SUPPORT WILL TIGHTEN/DEEPEN THE FRONTAL ZONE AS IT DROPS THROUGH SOUTHERN/EASTERN ZONES FRIDAY NIGHT...WITH AMPLE MOISTURE AND POTENTIAL FOR LOWER AMPLITUDE SHORTWAVE ENERGY TO PROPAGATE THROUGH IN SW FLOW PROBABLY ENOUGH TO HELP GENERATE ADDITIONAL RAIN/THUNDER ALONG FRONTAL SLOPE. WITH THAT SAID...ONCE AGAIN HELD SHY OF LIKELY POPS GIVEN NORMAL UNCERTAINTIES WITH CONVECTION AND RECENT MAINLY DRY FRONTAL PASSAGES IN SIMILAR SETUPS. A FEW SHOWERS/LOW CLOUDS MAY LINGER INTO SATURDAY MORNING ACROSS SOUTHERN/EASTERN ZONES...WITH THE REST OF THE WEEKEND INTO EARLY NEXT WEEK MUCH COOLER/DRIER AS BROAD HIGH PRESSURE BUILDS IN WAKE OF FRONT/SHORTWAVE TROUGH. RETURN FLOW TIMED WITH THE NEXT ROUND OF HEIGHT FALLS ON THE BACKSIDE OF THIS AREA OF HIGH PRESSURE BRINGS SHOWER/STORM CHANCES BACK INTO THE FORECAST BY THE MIDDLE OF NEXT WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 133 AM EDT THU SEP 4 2014 VFR CONDITIONS TO START THE PERIOD AND FOR THE MOST PART EXPECT VFR THROUGH THIS TAF PERIOD. EXCEPTION WILL BE POSSIBLE MVFR BR TOWARD DAYBREAK AT KFWA WITH LIGHT WINDS AND RESIDUAL LOW LEVEL MOISTURE. SATELLITE AND RADAR SHOWS TWO CONVECTIVE SYSTEMS WHICH HAVE DEVELOPED UPSTREAM...ONE ACROSS CENTRAL AND NORTHERN WI AND A SMALLER AREA OVER EASTERN IA. HIRES SHORT TERM GUIDANCE HAS SOME IDEA OF THESE AREAS BUT DETAILS NOT HANDLED WELL. WILL HAVE TO MONITOR BUT POINT PROBABILITIES TOO SMALL FOR ANY MENTION IN TAFS AT THIS TIME. ATMOSPHERE BECOMES MARGINALLY UNSTABLE TODAY WITH HEATING BUT NO TRIGGER MECHANISM AND DECENT CAPPING INVERSION SHOULD KEEP CONVECTION FROM FORMING. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SYNOPSIS...LASHLEY SHORT TERM...LASHLEY LONG TERM...STEINWEDEL AVIATION...LASHLEY VISIT US AT WWW.WEATHER.GOV/IWX (ALL LOWER CASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/NWSNORTHERNINDIANA WWW.TWITTER.COM/NWSIWX WWW.YOUTUBE.COM/NWSNORTHERNINDIANA
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1231 PM CDT THU SEP 4 2014 .SYNOPSIS... ISSUED AT 304 AM CDT THU SEP 4 2014 COLD FRONT FROM EASTERN SD INTO CO WILL MOVE SOUTHEAST ACROSS THE STATE BY FRIDAY MORNING. A WAVE WILL MOVE NORTHEAST ALONG THE FRONT ON FRIDAY...PASSING SOUTH OF IA DURING THE DAY. HIGH PRESSURE WILL BUILD INTO THE REGION FOR THE WEEKEND. NEXT FRONTAL SYSTEM SLATED TO MOVE THROUGH THE AREA ABOUT TUESDAY. && .SHORT TERM /TODAY/... ISSUED AT 304 AM CDT THU SEP 4 2014 MAIN FORECAST CONCERN WAS ANOTHER HOT AND HUMID DAY AND WITH POTENTIAL FOR CONVECTION LATE THIS AFTERNOON. LEANED TOWARD THE SLIGHTLY WARMER ECMWF/GFS FOR HIGHS TODAY AS THERE SHOULD BE SOME DECENT MIXING TO AROUND 900MB AND WAA THROUGHOUT THE DAY. THE WAA HAS KEPT TEMPS UP OVERNIGHT IN THE MID TO UPPER 70S. A SHARP COLD FRONT IS SLATED TO PUSH INTO NORTHWEST LATE THIS AFTERNOON INTO THE EVENING AND CAP LOOKS TO HOLD THROUGH MUCH OF THE DAY. THE HIRES MODELS (NMM/ARW) BREAK OUT SOME ISOLATED STORMS BY 19-20Z TODAY. HOWEVER...THE 04.00Z HOPWRF/04.05Z HRRR KEYING IN ON A VERY WEAK SHORTWAVE OVER SOUTHERN NEBRASKA AND HAS STORMS DEVELOPING BY AROUND 16-17Z. HOWEVER...BELIEVE THE STRONG CAP IN PLACE WILL HOLD UNTIL THE COLD FRONT LATER THIS AFTERNOON ENTERS THE STATE. ONE THING TO NOTE...IF WEAK ISOLATED CONVECTION THAT THE HOPWRF/HRRR DOES DEVELOP...WILL HINDER MAX TEMPS A LITTLE TODAY OVER THE SOUTH. AT ANY RATE...HAVE POPS INCREASING PAST 20Z OVER THE WEST TO NORTHWEST AS THE COLD FRONT BEGINS TO SAG SOUTHEAST INTO THE STATE. .LONG TERM /TONIGHT THROUGH WEDNESDAY/... ISSUED AT 304 AM CDT THU SEP 4 2014 THUNDERSTORMS ARE LIKELY TO DEVELOP ALONG AND JUST BEHIND THE COLD FRONT DAY AS IT SLIDES SOUTHEAST AIRMASS IS QUITE CAPPED INITIALLY...BUT COLD AIR ALOFT WILL ALLOW THE CAP TO BREAK AND EXPECT A LINE OF THUNDERSTORMS TO DEVELOP AND MOVE TROUGH THE STATE. RAIN WILL CONTINUE OVER THE SOUTH AND EAST ON FRIDAY AS A S/WV RESULTS IN A WAVE LIFTING NORTHEAST ALONG THE FRONT FRIDAY. HIGH PRESSURE WILL PUSH IN AND DOMINATE THE WEATHER OVER THE WEEKEND WITH COOLER AND DRIER AIR IN PLACE. THE NEXT FRONTAL SYSTEM WILL BE WEAKER...BUT WILL BRING A CHANCE FOR RAIN IN THE MONDAY TUESDAY TIMEFRAME. DO NOT EXPECT TO SEE THE WARMING WITH THE NEXT SYSTEM THAT IS OCCURRING BEFORE THE CURRENT COLD FRONT. FURTHER AHEAD...A STRONGER FRONT WILL BRING A CHANCE FOR RAIN ABOUT THURSDAY. MUCH COLDER AIR WILL SETTLE IN BEHIND THE FRONT LATER NEXT WEEK WITH THE A COOL PUSH OF FALL AIR OVER THE UPPER MIDWEST. THE MODELS HAVE BECOME MORE CONSISTENT WITH THIS BOTH IN MODEL TO MODEL AND RUN TO RUN CONTINUITY. && .AVIATION...04/18Z ISSUED AT 1231 PM CDT THU SEP 4 2014 A COLD FRONT IS APPROACHING FROM THE NORTHWEST AND WILL SWEEP ACROSS THE AREA THIS EVENING AND TONIGHT...ARRIVING AT OTM JUST BEFORE SUNSET FRIDAY. THE FRONT WILL BE ACCOMPANIED BY SOME THUNDERSTORMS AS IT MOVES THROUGH BUT AMOUNT OF COVERAGE IS VERY UNCERTAIN AT THIS TIME...THUS HAVE MAINTAINED JUST VCTS IN THE 18Z TAFS. LOWER CIGS WILL ALSO MOVE IN WITH/BEHIND THE FRONT BUT ARE MOSTLY EXPECTED TO BE VFR OUTSIDE OF STORMS. WINDS WILL SWITCH TO NNW BY FRIDAY MORNING. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...MS SEP 14 SHORT TERM...PODRAZIK LONG TERM...MS SEP 14 AVIATION...LEE
AREA FORECAST DISCUSSION
NWS DES MOINES IA
638 AM CDT THU SEP 4 2014 ...UPDATED AVIATION DISCUSSION... .SYNOPSIS... ISSUED AT 304 AM CDT THU SEP 4 2014 COLD FRONT FROM EASTERN SD INTO CO WILL MOVE SOUTHEAST ACROSS THE STATE BY FRIDAY MORNING. A WAVE WILL MOVE NORTHEAST ALONG THE FRONT ON FRIDAY...PASSING SOUTH OF IA DURING THE DAY. HIGH PRESSURE WILL BUILD INTO THE REGION FOR THE WEEKEND. NEXT FRONTAL SYSTEM SLATED TO MOVE THROUGH THE AREA ABOUT TUESDAY. && .SHORT TERM /TODAY/... ISSUED AT 304 AM CDT THU SEP 4 2014 MAIN FORECAST CONCERN WAS ANOTHER HOT AND HUMID DAY AND WITH POTENTIAL FOR CONVECTION LATE THIS AFTERNOON. LEANED TOWARD THE SLIGHTLY WARMER ECMWF/GFS FOR HIGHS TODAY AS THERE SHOULD BE SOME DECENT MIXING TO AROUND 900MB AND WAA THROUGHOUT THE DAY. THE WAA HAS KEPT TEMPS UP OVERNIGHT IN THE MID TO UPPER 70S. A SHARP COLD FRONT IS SLATED TO PUSH INTO NORTHWEST LATE THIS AFTERNOON INTO THE EVENING AND CAP LOOKS TO HOLD THROUGH MUCH OF THE DAY. THE HIRES MODELS (NMM/ARW) BREAK OUT SOME ISOLATED STORMS BY 19-20Z TODAY. HOWEVER...THE 04.00Z HOPWRF/04.05Z HRRR KEYING IN ON A VERY WEAK SHORTWAVE OVER SOUTHERN NEBRASKA AND HAS STORMS DEVELOPING BY AROUND 16-17Z. HOWEVER...BELIEVE THE STRONG CAP IN PLACE WILL HOLD UNTIL THE COLD FRONT LATER THIS AFTERNOON ENTERS THE STATE. ONE THING TO NOTE...IF WEAK ISOLATED CONVECTION THAT THE HOPWRF/HRRR DOES DEVELOP...WILL HINDER MAX TEMPS A LITTLE TODAY OVER THE SOUTH. AT ANY RATE...HAVE POPS INCREASING PAST 20Z OVER THE WEST TO NORTHWEST AS THE COLD FRONT BEGINS TO SAG SOUTHEAST INTO THE STATE. .LONG TERM /TONIGHT THROUGH WEDNESDAY/... ISSUED AT 304 AM CDT THU SEP 4 2014 THUNDERSTORMS ARE LIKELY TO DEVELOP ALONG AND JUST BEHIND THE COLD FRONT DAY AS IT SLIDES SOUTHEAST AIRMASS IS QUITE CAPPED INITIALLY...BUT COLD AIR ALOFT WILL ALLOW THE CAP TO BREAK AND EXPECT A LINE OF THUNDERSTORMS TO DEVELOP AND MOVE TROUGH THE STATE. RAIN WILL CONTINUE OVER THE SOUTH AND EAST ON FRIDAY AS A S/WV RESULTS IN A WAVE LIFTING NORTHEAST ALONG THE FRONT FRIDAY. HIGH PRESSURE WILL PUSH IN AND DOMINATE THE WEATHER OVER THE WEEKEND WITH COOLER AND DRIER AIR IN PLACE. THE NEXT FRONTAL SYSTEM WILL BE WEAKER...BUT WILL BRING A CHANCE FOR RAIN IN THE MONDAY TUESDAY TIMEFRAME. DO NOT EXPECT TO SEE THE WARMING WITH THE NEXT SYSTEM THAT IS OCCURRING BEFORE THE CURRENT COLD FRONT. FURTHER AHEAD...A STRONGER FRONT WILL BRING A CHANCE FOR RAIN ABOUT THURSDAY. MUCH COLDER AIR WILL SETTLE IN BEHIND THE FRONT LATER NEXT WEEK WITH THE A COOL PUSH OF FALL AIR OVER THE UPPER MIDWEST. THE MODELS HAVE BECOME MORE CONSISTENT WITH THIS BOTH IN MODEL TO MODEL AND RUN TO RUN CONTINUITY. && .AVIATION...04/12Z ISSUED AT 638 AM CDT THU SEP 4 2014 WINDS WILL CONTINUE TO INCREASE THIS MORNING AS MIXING TO AROUND 2000-2500 FEET BY 21Z THIS AFTERNOON AND WITH THE PRESSURE GRADIENT STRENGTHENING...INCREASED WIND GUSTS FOR ALL TAF SITES. KEPT MENTION OF VCTS AS LOW CONFIDENCE WITH LOCATION OF CONVECTION LATE THIS AFTERNOON INTO THE EVENING. POTENTIAL FOR MVFR VIS/CIGS TONIGHT AND WILL HAVE TO BE REEVALUATED AT THE 18Z TAFS. OTHERWISE...COLD FRONT THROUGH THIS EVENING WILL SHIFT WINDS TO THE WEST THEN NORTHWEST TOWARD FRIDAY MORNING. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...MS SEP 14 SHORT TERM...PODRAZIK LONG TERM...MS SEP 14 AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
331 AM CDT THU SEP 4 2014 .SYNOPSIS... ISSUED AT 304 AM CDT THU SEP 4 2014 COLD FRONT FROM EASTERN SD INTO CO WILL MOVE SOUTHEAST ACROSS THE STATE BY FRIDAY MORNING. A WAVE WILL MOVE NORTHEAST ALONG THE FRONT ON FRIDAY...PASSING SOUTH OF IA DURING THE DAY. HIGH PRESSURE WILL BUILD INTO THE REGION FOR THE WEEKEND. NEXT FRONTAL SYSTEM SLATED TO MOVE THROUGH THE AREA ABOUT TUESDAY. && .SHORT TERM /TODAY/... ISSUED AT 304 AM CDT THU SEP 4 2014 MAIN FORECAST CONCERN WAS ANOTHER HOT AND HUMID DAY AND WITH POTENTIAL FOR CONVECTION LATE THIS AFTERNOON. LEANED TOWARD THE SLIGHTLY WARMER ECMWF/GFS FOR HIGHS TODAY AS THERE SHOULD BE SOME DECENT MIXING TO AROUND 900MB AND WAA THROUGHOUT THE DAY. THE WAA HAS KEPT TEMPS UP OVERNIGHT IN THE MID TO UPPER 70S. A SHARP COLD FRONT IS SLATED TO PUSH INTO NORTHWEST LATE THIS AFTERNOON INTO THE EVENING AND CAP LOOKS TO HOLD THROUGH MUCH OF THE DAY. THE HIRES MODELS (NMM/ARW) BREAK OUT SOME ISOLATED STORMS BY 19-20Z TODAY. HOWEVER...THE 04.00Z HOPWRF/04.05Z HRRR KEYING IN ON A VERY WEAK SHORTWAVE OVER SOUTHERN NEBRASKA AND HAS STORMS DEVELOPING BY AROUND 16-17Z. HOWEVER...BELIEVE THE STRONG CAP IN PLACE WILL HOLD UNTIL THE COLD FRONT LATER THIS AFTERNOON ENTERS THE STATE. ONE THING TO NOTE...IF WEAK ISOLATED CONVECTION THAT THE HOPWRF/HRRR DOES DEVELOP...WILL HINDER MAX TEMPS A LITTLE TODAY OVER THE SOUTH. AT ANY RATE...HAVE POPS INCREASING PAST 20Z OVER THE WEST TO NORTHWEST AS THE COLD FRONT BEGINS TO SAG SOUTHEAST INTO THE STATE. .LONG TERM /TONIGHT THROUGH WEDNESDAY/... ISSUED AT 304 AM CDT THU SEP 4 2014 THUNDERSTORMS ARE LIKELY TO DEVELOP ALONG AND JUST BEHIND THE COLD FRONT DAY AS IT SLIDES SOUTHEAST AIRMASS IS QUITE CAPPED INITIALLY...BUT COLD AIR ALOFT WILL ALLOW THE CAP TO BREAK AND EXPECT A LINE OF THUNDERSTORMS TO DEVELOP AND MOVE TROUGH THE STATE. RAIN WILL CONTINUE OVER THE SOUTH AND EAST ON FRIDAY AS A S/WV RESULTS IN A WAVE LIFTING NORTHEAST ALONG THE FRONT FRIDAY. HIGH PRESSURE WILL PUSH IN AND DOMINATE THE WEATHER OVER THE WEEKEND WITH COOLER AND DRIER AIR IN PLACE. THE NEXT FRONTAL SYSTEM WILL BE WEAKER...BUT WILL BRING A CHANCE FOR RAIN IN THE MONDAY TUESDAY TIMEFRAME. DO NOT EXPECT TO SEE THE WARMING WITH THE NEXT SYSTEM THAT IS OCCURRING BEFORE THE CURRENT COLD FRONT. FURTHER AHEAD...A STRONGER FRONT WILL BRING A CHANCE FOR RAIN ABOUT THURSDAY. MUCH COLDER AIR WILL SETTLE IN BEHIND THE FRONT LATER NEXT WEEK WITH THE A COOL PUSH OF FALL AIR OVER THE UPPER MIDWEST. THE MODELS HAVE BECOME MORE CONSISTENT WITH THIS BOTH IN MODEL TO MODEL AND RUN TO RUN CONTINUITY. && .AVIATION...04/06Z ISSUED AT 1157 PM CDT WED SEP 3 2014 SOUTHERLY WINDS EXPECTED TO CONTINUE WITH VFR CONDITIONS THROUGH THE TAF PERIOD. A COLD FRONT WILL SWEEP ACROSS THE STATE LATE THURSDAY EVENING INTO THE OVERNIGHT HOURS. BROUGHT IN SOME LOW VFR CIGS TOWARD THE END OF THE FORECAST PERIOD AS THE FRONT NEARS THE TAF SITES...AND SOME VCTS ACROSS THE NORTHERN TAF SITES WITH THUNDERSTORM ACTIVITY EXPECTED ALONG AND NEAR THE FRONTAL BOUNDARY. WINDS WILL SHIFT AROUND TO THE NORTHWEST BEHIND THE FRONT. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...MS SEP 14 SHORT TERM...PODRAZIK LONG TERM...MS SEP 14 AVIATION...BEERENDS
AREA FORECAST DISCUSSION
NWS GOODLAND KS
200 PM MDT THU SEP 4 2014 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 158 PM MDT THU SEP 4 2014 WV LOOP AND RAP ANALYSIS SHOWS EXPANSIVE UPPER RIDGE JUST TO OUR SOUTHEAST WITH PLUME OF MID LEVEL MOISTURE MOVING NORTHEASTWARD ACROSS THE SOUTHWEST CONUS IN TO THE CENTRAL ROCKIES. CIRRUS WAS OVERSPREADING THE CENTRAL HIGH PLAINS. AHEAD OF AN EASTWARD MOVING POSITIVELY TILTED SHORTWAVE TROUGH OVER THE NORTHERN PLAINS. A COLD FRONT FORCED BY THE AFOREMENTIONED TROUGH HAS MADE IT THROUGH THE FORECAST AREA AND TEMPERATURES WERE NOTICEABLY COOLER THAN 24 HOURS PRIOR. MID TO UPPER 70S WERE COMMON IN THE NORTHWEST HALF OF THE FORECAST AREA WHICH SAW THE EARLIEST FRONTAL PASSAGE. WINDS IMMEDIATELY BEHIND THE FRONT GUSTED FROM THE NORTH AT 30-35 MPH BUT HAVE SUBSIDED SOME THIS AFTERNOON. STILL...DIURNAL HEATING AND MIXING IS CONTRIBUTING TO GUSTS APPROACHING 30 MPH. WINDS WILL CONTINUE TO DECREASE THROUGH THE AFTERNOON...ESPECIALLY WHEN MIXING LESSENS THIS EVENING. CHALLENGES FOR THE SHORT TERM INCLUDE PRECIPITATION CHANCES THIS EVENING THROUGH TOMORROW AND THE POSSIBILITY OF MARGINALLY SEVERE HAIL WITH A FEW OF THE THUNDERSTORMS THIS EVENING. LOCALLY HEAVY RAINFALL WILL BE POSSIBLE GIVEN PWAT VALUES APPROACHING 2 STANDARD DEVIATIONS ABOVE CLIMO FOR EARLY SEPTEMBER. EVENT QPF TOTALS WILL BE AROUND ONE INCH FOR THE FAR SOUTH PORTION OF THE FORECAST AREA TAPERING TO A TENTH OF AN INCH OR LESS IN THE FAR NORTHWEST PORTION OF THE AREA. STILL SOME UNCERTAINTY ON QPF AMOUNTS AND EXACT PLACEMENT OF HEAVIER TOTALS ALTHOUGH SHORT RANGE GUIDANCE HAS COME INTO BETTER AGREEMENT WITH TIMING. SHOWERS AND THUNDERSTORMS SHOULD DEVELOP ACROSS THE SOUTHERN PORTION OF THE AREA NEAR AND JUST NORTH OF THE FRONT LATER THIS EVENING AND THEN CONTINUE TO DEVELOP NORTHWARD AS ISENTROPIC LIFT INCREASES ON THE COOL SIDE OF THIS BOUNDARY. THE STRONGEST CONVECTION SHOULD OCCUR THROUGH THE EVENING AND EARLY TONIGHT BEFORE INSTABILITY WANES. ISOLATED MARGINALLY SEVERE HAIL SEEMS POSSIBLE GIVEN 30-40 KNOT DEEP LAYER SHEAR AND AROUND 1000 J/KG MUCAPE. THIS THREAT SHOULD BE CONFINED TO THE SOUTHERN PORTION OF THE AREA. LATER IN THE NIGHT SHOWERS AND THUNDERSTORMS SHOULD BECOME FAIRLY WIDESPREAD AS ISENTROPIC LIFT MAXIMIZES OVER THE AREA...PARTICULARLY IN THE SOUTHEASTERN PORTION WHERE HIGHER QPF AMOUNTS ARE. MODELS HAVE TRENDED SLOWER SO ENDING TIME OF THE PRECIPITATION EVENT IS A LITTLE UNCERTAIN BUT BY MID/LATE MORNING THE HEAVIEST PRECIPITATION WILL HAVE SHIFTED EAST OF THE AREA. SOME SHOWERS WILL LINGER IN THE SOUTHEAST THROUGH THE AFTERNOON BEFORE THE UPPER LEVEL TROUGH AXIS MOVES THROUGH. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 158 PM MDT THU SEP 4 2014 FRIDAY NIGHT THERE MAYBE SOME LINGERING RAINFALL OVER THE FAR EAST/SOUTHEAST PART OF THE AREA AHEAD OF THE DEPARTING 500MB SHORT WAVE TROUGH. THE RAINFALL SHOULD BE EAST OF THE AREA BY MID TO LATE EVENING. DUE TO THE LOWEST 50MB OR SO OF THE SOUNDINGS REMAINING SATURATED THOUGHT ABOUT MENTIONING FOG IN THE FORECAST LATE FRIDAY NIGHT. HOWEVER LOOKS LIKE THE CLOUD COVER WILL REMAIN OVER THE AREA. IF SKIES CLEAR OVERNIGHT FOG WILL BE MUCH MORE LIKELY TO DEVELOP. A SURFACE HIGH MOVES THROUGH THE AREA SO WINDS WILL BECOME LIGHT AND VARIABLE. WITH A COOL AIR MASS IN PLACE LOWS WILL BE WELL BELOW NORMAL. SATURDAY AND SATURDAY NIGHT VERY WEAK RIPPLES IN THE UPPER LEVEL FLOW MOVE OVER THE AREA. SOUNDINGS SHOW A CAPPED UNSATURATED ENVIRONMENT SO THESE TWO PERIODS WILL BE DRY. DURING THE DAY THE SURFACE HIGH MOVES EAST WHICH WILL ALLOW WARMER AIR FROM THE SOUTH TO MOVE INTO THE AREA. SATURDAY NIGHT WILL BE A FEW DEGREES WARMER THAN FRIDAY NIGHT. SUNDAY THROUGH THURSDAY NUMEROUS WEAK UPPER LEVEL DISTURBANCES WILL MOVE ACROSS THE AREA. LATEST RUN OF MODELS DISAGREES WITH THE PROGRESSION AND LOCATION OF THE STRONGER UPPER LEVEL SHORT WAVE TROUGH THAT WILL MOVE THROUGH MONDAY THROUGH TUESDAY...THUS LOWERING CONFIDENCE OF WHEN/WHERE RAINFALL WILL DEVELOP. TUESDAY THROUGH WEDNESDAY A STRONGER MORE WELL DEFINED UPPER LEVEL SHORT WAVE TROUGH WILL MOVE THROUGH THE AREA...SO WILL HAVE HIGHER RAINFALL CHANCES AS A RESULT. A STRONG COLD FRONT MOVES THROUGH WEDNESDAY EVENING BUT MOISTURE AND UPPER LEVEL FORCING DO NOT LOOK VERY FAVORABLE FOR STORM DEVELOPMENT AS THE FRONT MOVES THROUGH. TEMPERATURES FOR THE PERIOD WILL GRADUALLY WARM THROUGH TUESDAY AS THE COOLER AIR MASS GRADUALLY MOVES EAST. MID WEEK A STRONG COLD FRONT MOVES INTO THE AREA WEDNESDAY NIGHT WITH THE COOLER AIR CONTINUING TO MOVE INTO THE AREA THURSDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1141 AM MDT THU SEP 4 2014 WINDS WILL GRADUALLY SUBSIDE THIS AFTERNOON AS THE COLD FRONT CONTINUES TO MOVE SOUTHWARD AWAY FROM THE AREA. FOR THE NEXT FEW HOURS GUSTS IN THE 25-30 KNOT RANGE ARE EXPECTED AT BOTH KGLD AND KMCK. CLOUDS WILL LOWER AND THICKEN THROUGHOUT THE REST OF THE DAY BUT VFR CONDITIONS SHOULD PREVAIL UNTIL AFTER 06Z. SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE THIS EVENING WITH A GOOD CHANCE OF AT LEAST INTERMITTENT IMPACT TO BOTH TERMINALS OVER NIGHT AND EARLY TOMORROW. MVFR IS LIKELY FOR A PERIOD LATE TONIGHT DUE MAINLY TO LOW CEILINGS AND CONDITIONS COULD APPROACH IFR AT LEAST BRIEFLY TOMORROW MORNING. THUNDER WILL BE MOST LIKELY AT KGLD LATE THIS EVENING AND EARLY TONIGHT...BUT AT LEAST A LOW CHANCE EXISTS AT KMCK ALSO LATER TONIGHT. THE MORE WIDESPREAD RAIN WILL MOVE EAST OF BOTH TERMINALS BY MID MORNING THOUGH MVFR CEILINGS MAY LINGER THROUGH THE END OF THE TAF PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...BRB LONG TERM...JTL AVIATION...BRB
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1101 PM MDT WED SEP 3 2014 .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 150 PM MDT WED SEP 3 2014 WARM SOUTHWESTERLY MID LEVEL FLOW AND DEEP MIXING HAS RESULTED IN SIGNIFICANTLY ABOVE NORMAL TEMPERATURES TODAY WELL INTO THE 90S AT MOST LOCATIONS. SOME HIGH BASED CU HAS FORMED EARLY THIS AFTERNOON MAINLY OVER EASTERN COLORADO AND A FEW ISOLATED SHOWERS/STORMS ARE POSSIBLE LATE THIS AFTERNOON AND EVENING. THE BEST CHANCE WILL BE THE FAR SOUTHERN PORTION OF THE FORECAST AREA WHERE RAP SOUNDINGS SHOW DEEP MIXING BUT MORE BOUNDARY LAYER MOISTURE AND INSTABILITY THAN FURTHER NORTH. AN UPPER LEVEL SHORTWAVE IS EVIDENT ON WATER VAPOR IMAGERY OVER THE NORTHERN ROCKIES MOVING EASTWARD. THIS SHORTWAVE WILL MOVE INTO THE NORTHERN PLAINS TONIGHT FORCING SURFACE CYCLOGENESIS TO OUR NORTH. TIGHTENING SURFACE PRESSURE GRADIENT WILL RESULT IN INCREASING WINDS BACKING TO MORE OF A SOUTHERLY DIRECTION THIS EVENING AND INTO THE NIGHT. SUFFICIENT MIXING AND LESS LOW LEVEL MOISTURE THAN PREVIOUS NIGHTS SHOULD PRECLUDE A FOG THREAT OVERNIGHT. A COLD FRONT WILL EVOLVE FROM LEE TROUGHING AND SURGE SOUTHWARD ACROSS THE FORECAST AREA TOMORROW MORNING BRINGING COOLER TEMPERATURES. WARM/MOIST ADVECTION OVER SURFACE BOUNDARY WILL RESULT IN SHOWERS AND THUNDERSTORMS INCREASING BY LATE IN THE DAY TOMORROW ACROSS THE SOUTHWESTERN PORTION OF THE AREA AND ESPECIALLY JUST AFTER THE SHORT TERM PERIOD. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 242 PM MDT WED SEP 3 2014 THURSDAY NIGHT AND FRIDAY WIDESPREAD RAINFALL...HEAVY AT TIMES...LOOKS VERY LIKELY FOR THE AREA. THURSDAY NIGHT MID AND UPPER LEVEL MIXING RATIOS INCREASE AHEAD OF A COMPACT UPPER LEVEL SHORT WAVE TROUGH THAT WILL MOVE ACROSS THE AREA THROUGH THE NIGHT. AHEAD OF THE TROUGH ELEVATED CAPE DEVELOPS AS THE JET AT 750MB NOSES IN THE FROM THE SOUTHEAST...AND PROGRESSES NORTHWEST ACROSS MOST OF THE AREA THROUGH THE NIGHT. WITH ISENTROPIC AS WELL AS SYNOPTIC LIFT OCCURRING ALONG THE NOSE OF THIS JET...ANTICIPATE ELEVATED STORMS TO DEVELOP ALONG IT BY EARLY EVENING. ELEVATED CAPE ABOVE 750MB MAY BE AS HIGH AS 2500J/KG ALONG AND SOUTHEAST OF THE NOSE OF THE 750MB JET...WITH INSTABILITY DECREASING DRAMATICALLY NORTHWEST OF THE NOSE. IF STORMS ARE ABLE TO TAP INTO THE HIGHER INSTABILITY HAIL UP TO 2 INCHES IN DIAMETER WILL BE POSSIBLE DUE TO DEEP LAYER SHEAR OF 35KTS. HOWEVER FURTHER NORTHWEST OF THE JET NOSE HAIL SIZE WILL TAPPER OFF DRAMATICALLY DUE TO LITTLE TO NO ELEVATED CAPE. PLACED SEVERE WORDING IN THE FORECAST WHERE SEVERE STORMS WILL BE MOST LIKELY. IN ADDITION TO THE LARGE HAIL...MEAN STORM MOTION WILL BE AROUND 20MPH AND WILL BE PARALLEL TO THE NOSE OF THE 750MB JET. THIS WILL LEAD TO SLOW MOVING TRAINING STORMS CAPABLE OF PRODUCING HEAVY RAINFALL. ANTICIPATE STORMS TO START OFF AS MORE SUPER CELLULAR IN THE EVENING WHEN ELEVATED CAPE IS HIGHEST. OVERNIGHT AS THE ELEVATED INSTABILITY DIMINISHES AND ICE NUCLEI SEEDING FROM UPWIND STORMS OCCURS...BELIEVE THE HAIL SIZE WILL BECOME SMALLER THAN ONE INCH IN DIAMETER. HOWEVER HEAVY RAINFALL WILL BECOME MORE OF A THREAT. FURTHER NORTHWEST OF THE NOSE OF THE 750MB JET 700-500MB THETA-E LAPSE RATES INDICATE A CONVECTIVELY UNSTABLE ENVIRONMENT DESPITE THE LACK OF ELEVATED CAPE. WITH UPPER LEVEL SHORT WAVE TROUGH MOVING ACROSS MOST OF THE AREA THROUGH THE NIGHT DECIDED TO KEEP THE RAINFALL CHANCES GOING FOR THE REST OF THE AREA...WITH THE BEST CHANCE FOR RAINFALL ACTUALLY SHIFTING NORTH TOWARD THE NE BORDER OVERNIGHT FOLLOWING THE HIGHER 700-500MB MIXING RATIOS AND 700-500MB FRONTOGENESIS. ASIDE FROM THE WIDESPREAD RAINFALL...A SECOND SURGE OF COOLER AIR WILL MOVE INTO THE AREA FROM THE NORTH THROUGH THE NIGHT. FRIDAY MORNING THE UPPER LEVEL SHORT WAVE TROUGH FROM LAST NIGHT WILL EXIT THE AREA AS ANOTHER SHORT WAVE TROUGH DEEPENS OVER THE WESTERN PART OF THE AREA. MEANWHILE THE BAND OF 700-500MB FRONTOGENESIS STRENGTHENS THROUGH THE DAY AND MOVES EAST ACROSS THE AREA AHEAD OF THIS SECOND SHORT WAVE TROUGH. CAPE WILL BE AROUND 1000J/KG OR LESS SO DO NOT ANTICIPATE A SEVERE THREAT SINCE THE CAPE PROFILE WILL BE TALL AND NARROW WHICH FAVORS HEAVY RAINFALL. MEAN STORM MOTION WILL CONTINUE TO BE AROUND 20MPH ALSO FAVORING HEAVY RAINFALL. ANTICIPATE THE RAINFALL TO END FROM WEST TO EAST DURING THE AFTERNOON AS THE UPPER LEVEL SHORT WAVE TROUGH EXITS THE AREA. DUE TO THE COUPLE ROUNDS OF HEAVY RAINFALL POSSIBLE...A FLASH FLOOD WATCH MAY BE NEEDED BUT WILL HOLD OFF FOR NOW IN ORDER TO GET A GOOD HANDLE AS TO WHERE THE FLOODING THREAT WILL BE MOST LIKELY. FRIDAY EVENING THERE MAY BE SOME LINGERING SHOWERS OVER THE EASTERN PART OF THE AREA AS THE SHORT WAVE TROUGH MOVES EAST. DURING THE LATE EVENING AND OVERNIGHT HOURS ANOTHER LESS COMPACT UPPER LEVEL SHORT WAVE TROUGH WILL MOVE THROUGH THE AREA. CURRENTLY THE SOUTH HALF TO 1/3 HAS THE BEST LIFT AND INSTABILITY SO WILL HAVE THE HIGHER RAINFALL CHANCES THERE. SATURDAY THROUGH WEDNESDAY NUMEROUS UPPER LEVEL SHORT WAVE TROUGHS MOVE ACROSS THE AREA. TWO STRONGER SHORT WAVE TROUGHS WILL MOVE THROUGH MONDAY AFTERNOON AND MONDAY NIGHT. AS A RESULT WILL HAVE HIGHER RAINFALL CHANCES FOR MONDAY NIGHT. OTHERWISE LOW RAINFALL CHANCES ARE FORECAST FOR VARIOUS PARTS OF THE AREA AS THE WEAKER UPPER LEVEL DISTURBANCES MOVE THROUGH. TEMPERATURES FOR THE PERIOD WILL START OFF COOLER THAN NORMAL THEN GRADUALLY WARM TO NEAR NORMAL AS THE COOLER AIR MASS MOVES EAST OF THE AREA. WEDNESDAY ANOTHER COLD FRONT WILL MOVE INTO THE AREA BRINGING BELOW NORMAL TEMPERATURES WITH IT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1100 PM MDT WED SEP 3 2014 VFR CONDITIONS EXPECTED AT KGLD AND KMCK THROUGH THE PERIOD. KGLD...SOUTHWEST WINDS 20KTS WITH HIGHER GUSTS AT TAF ISSUANCE WILL REMAIN THROUGH 10Z. AROUND 11Z WINDS VEER TO THE SOUTHWEST AROUND 12KTS THEN QUICKLY SHIFT TO THE NORTH/NORTHWEST AT 18G28KTS POSSIBLY HIGHER BY 14Z AS A COLD FRONT AND NICE 3 HOUR PRESSURE RISE COUPLET MOVE THROUGH. AROUND 18Z WINDS SUBSIDE JUST A BIT AS THE COUPLET MOVES AWAY BUT STILL EXPECTING NORTH WINDS GUSTING A BIT OVER 20KTS. BY 23Z A SLOW VEER TO THE NORTHEAST EXPECTED WITH SPEEDS AROUND 13KTS. MODELS HINT AT A BIT OF MOISTURE AROUND 2K FT DURING THE THE FRONTAL PASSAGE...RIGHT NOW NOT EXPECTING A BKN DECK AT MVFR CATEGORY. PRECIPITATION CHANCES SHOULD HOLD OFF TIL 05Z WHEN SHOWERS/THUNDERSTORMS APPROACH THE TERMINAL FROM THE SOUTHWEST. KMCK...SOUTH WINDS AROUND 13KTS AT TAF ISSUANCE EXPECTED FOR A FEW HOURS BEFORE FALLING JUST BELOW 12KTS BY 08Z. COLD FRONT MOVES THROUGH AROUND 14Z WITH NORTH WINDS 17G27KTS AS PRESSURE RISE COUPLET MOVES THROUGH. BY 22Z WINDS VEER TO THE NORTHEAST AROUND 13KTS. SIMILAR TO KGLD MOISTURE AROUND 2.5K FT MAY PRODUCE A FEW CLOUDS FOR A FEW HOURS AROUND 14Z...NOT EXPECTED ENOUGH TO CREATE A BKN DECK AND HIT MVFR CATEGORY. NO PRECIPITATION EXPECTED. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...BRB LONG TERM...JTL AVIATION...99
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1149 PM CDT Wed Sep 3 2014 ...Update to aviation forecast discussion... .SHORT TERM...(This Evening through Thursday) Issued at 345 PM CDT WED SEP 3 2014 Water vapor loop shows relatively zonal flow across the Central Plains with weak disturbances moving through. One vort max appears to be along the border between northwest KS and southwest NE and seems to be associated with thunderstorm cluster moving into eastern Nebraska. HRRR has been the only model that developed convection into central KS this evening, and has done so for the last several runs. RAP just recently has forecast precip into same general area in the next several hours. Meanwhile, all other models are keeping central and eastern KS dry tonight. Confidence is not high enough that HRRR is right, and thus have continued with POPs below 20% for tonight in forecast area. Good pressure gradient across the area tonight will maintain southerly winds of 10 to 15 kts most areas. This should help keep minimum temperatures up in the lower to middle 70s. On Thursday, more sunshine than today and warm temperature aloft will allow highs to reach the mid 90s most areas. Combined with dewpoints generally in the upper 60s to lower 70s, peak afternoon heat indices should reach the 100 to 105 range. Frontal boundary approaches northwest corner of our CWA around 21Z on Thursday, thus the chance of late afternoon thunderstorms is continued in that area. .LONG TERM...(Thursday Night through Wednesday) Issued at 345 PM CDT WED SEP 3 2014 Models are in good agreement that the cold front will traverse the county warning area Thursday night into midday Friday...although the GFS is the fastest. Convection that develops along and front Thursday night will have the greatest impact with coverage and rainfall amounts across the northern 1/3 of the cwa through sunrise Friday as the front advances southeastward. Will range pops from likely in the northwest counties to only a slight chance in the far southeast near Garnett...then keep higher end chance pops all areas on Friday along and behind the frontal passage and the approach of a shortwave trough from the central high plains. This wave will move east of the cwa early Saturday with diminishing chances for rain north to south as much drier air overspreads the area. With the frontal passage/cold air advection/clouds and precip in the area will see much cooler highs from the upper 60s around Belleville to the middle 80s south of I 35. This will set the stage for lows in the 50s most areas Friday night and Saturday night. With the dry air in place and high pressure center over the area...will keep the area dry late Saturday through Sunday with highs in the 70s both days. With the flow aloft slowly transitioning from northwest on Saturday to a more unsettled west to southwest flow into next week. As it does...the chances for more thunderstorms will increase and so will the high temperatures ahead of the next front which is expected by early Wednesday as a larger scale upper trough moves into the plains. Will introduce pops in the north central by Sunday night and then across the remainder of the cwa Monday into Wednesday. Highs will generally be in the 80s...cooling slightly into the upper 70s and lower 80s by Wednesday. && .AVIATION...(For the 06Z TAFs through 06Z Thursday Night) Issued at 1147 PM CDT WED SEP 3 2014 VFR conditions expected through most of the taf sites. There may be an occasional gusts under 20 kts at TOP/FOE overnight. As a front approaches tomorrow there is a slight chance that thunderstorms developing along that front could reach the taf sites towards the end of the period. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GDP LONG TERM...63 AVIATION...Sanders
AREA FORECAST DISCUSSION
NWS JACKSON KY
1054 PM EDT FRI SEP 5 2014 .UPDATE... ISSUED AT 1048 PM EDT FRI SEP 5 2014 LATEST TRACKING OF THE LINE OF STORMS TO OUR NW BRINGS THE LINE JUST TO THE NORTH OF THE CWA BETWEEN 7 AND 8Z THIS MORNING. SO FAR THE LATEST HRRR SEEMS TO BE FAIRLY WELL ON TRACK WITH THE ONGOING CONVECTION...AS DOES THE 00Z NAM12. BOTH MODELS POINT AT THE LINE EXPANDING AS IT NEARS THE OHIO RIVER VALLEY...WITH STORMS DEVELOPING OUT AHEAD OF THE MAIN LINE. THE HRRR IS A BIT QUICKER IN PULLING THESE SHOWERS AND THUNDERSTORMS INTO EASTERN KY AS COMPARED TO THE NAM12...AND SEEMS TO BE FOLLOWING THE CURRENT STORM MOTION BETTER THAN THE NAM12 AS WELL. THE ECMWF ALSO SUPPORTS THE HRRR SOLUTION...SO CHOSE TO RELY MORE HEAVILY ON THIS COMBINATION. IF BOTH THE HRRR AND ECMWF HOLD TRUE...INITIAL ISOLATED CONVECTION WILL SPREAD INTO THE NORTHERN COUNTIES OF THE CWA BETWEEN 9 AND 12Z...WITH THE MAIN LINE PASSING THROUGH SOMEWHERE CLOSER TO 18Z. THIS SEEMS TO BE FAIRLY ON TRACK WITH THE ONGOING FORECAST...SO HAVE MADE NO CHANGES FROM THE PREVIOUS UPDATE EARLIER THIS EVENING. THERE IS STILL A FAIRLY GOOD DEW POINT DEPRESSION ACROSS THE WESTERN AND NORTHERN PORTION OF THE CWA AT THE MOMENT. HOWEVER...A CONTINUED BREAK IN THE CLOUDS FOR THE NEXT FEW HOURS COULD BE ENOUGH TO PULL TEMPS DOWN AND ALLOW PATCHY FOG TO DEVELOP. GIVEN THE RAIN SHOWERS THIS EVENING OVER THE EASTERN CWA...DEW POINT DEPRESSIONS ARE MUCH LOWER HERE...SO EXPECT SOME PATCHY FOG TO PERHAPS BEGIN DEVELOPING A LITTLE SOONER IN THESE LOCATIONS. THIS MIGHT END UP BEING AN HOUR OR TWO SOONER THAN WHEN THE FOG IS MENTIONED IN THE GRIDS. OTHERWISE...THE ONLY OTHER UPDATE MADE WAS TO LOAD IN THE LATEST OBSERVATIONAL DATA FOR TEMPS...WINDS...AND DEW POINTS TO MAKE SURE CURRENT CONDITIONS WERE REFLECTED IN THE NEAR TERM FORECAST. THIS UPDATE RESULTED IN VERY LITTLE CHANGE FROM THE ONGOING FORECAST. UPDATE ISSUED AT 757 PM EDT FRI SEP 5 2014 GIVEN THE CURRENT RADAR TRENDS...AND LATEST HIRES MODEL DATA...DECIDED TO PUSH BACK THE ONSET OF SHOWERS AND THUNDERSTORMS BY SEVERAL HOURS. ORIGINAL FORECAST HAD SLIGHT CHANCES MOVING INTO THE FAR NW COUNTIES WITHIN THE NEXT 1 TO 2 HOURS. UNFORTUNATELY...THE LINE OF SHOWERS AND THUNDERSTORMS IS STILL OVER ILLINOIS AND NORTHERN INDIANA...AND IS NOT EXPECTED TO REACH KY FOR ANOTHER SEVERAL HOURS. EXPECT THAT WE WILL REMAIN DRY IN EASTERN KY THROUGH MUCH OF THE NIGHT...WITH SLIGHT CHANCES MOVING IN LATE TONIGHT IN THE NW...AND SLOWLY SPREADING SE NEAR DAWN. THIS ALSO SEEMED TO MATCH UP BETTER WITH SOME OF OUR SURROUNDING OFFICES. WOULD NOT BE SURPRISED THAT POPS MAY HAVE TO BE PUSHED BACK EVEN FURTHER LATER THIS EVENING/OVERNIGHT...UNLESS SOMETHING DEVELOPS OUT AHEAD OF THE MAIN LINE...BUT WILL WAIT TO SEE HOW THE CURRENT FORECAST PANS OUT FOR THE NEXT SEVERAL HOURS. STILL EXPECT PATCHY TO AREAS OF FOG TO DEVELOP AHEAD OF THE RAIN OVERNIGHT...SO LEFT FOG FORECAST UNTOUCHED FOR NOW. LOADED IN THE LATEST OBSERVATIONAL GUIDANCE FOR TEMPS...DEW POINTS...AND WINDS TO MAKE SURE THE NEAR TERM FORECAST WAS WELL ON TRACK WITH CURRENT CONDITIONS. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 415 PM EDT FRI SEP 5 2014 AS OF THE MID TO LATE AFTERNOON HOURS...AN UPPER LEVEL RIDGE OF HIGH PRESSURE REMAINS ACROSS THE SOUTHEASTERN CONUS WITH AN UPPER LEVEL TROUGH OVER THE NORTHERN AND CENTRAL PLAINS. ONE SHORTWAVE WAS WORKING ACROSS THE CENTRAL PLAINS...WHILE ANOTHER WAS WORKING EAST NEAR THE US/CANADIAN BORDER. THE SOUTHERN SHORTWAVE WILL WORK EAST AND INTO THE MID MS AND LOWER OH VALLEY REGION LATE TONIGHT AND INTO TOMORROW...THEN SLOWLY EAST ACROSS THE COMMONWEALTH THROUGH THE END OF THE PERIOD. THE NORTHERN SHORTWAVE IS PROJECTED TO WORK INTO THE NORTHEASTERN US DURING THAT TIME. THE PATTERN WILL RESULT IN TROUGH ACROSS THE NORTHEASTERN US AND OH VALLEY REGION BY THE END OF THE PERIOD. A COLD FRONT IN ADVANCE OF THIS TROUGH WILL WORK INTO THE OH VALLEY TONIGHT AND THEN ACROSS THE AREA THROUGH EARLY ON SATURDAY AFTERNOON. HIGH PRESSURE WILL BEGIN TO BUILD INTO THE ARE BEHIND THE FRONT ON SATURDAY EVENING AND SATURDAY NIGHT AND START TO USHER IN A COOLER AND LESS HUMID AIRMASS. CONVECTION HAS GENERALLY WANED OVER THE PAST COUPLE OF HOURS AS MUCH OF THE REGION HAS BEEN WORKED OVER. HOWEVER...ISOLATED CONVECTION LINGERS ACROSS THE BIG SANDY REGION AND THE VA BORDER COUNTIES. WE OPTED TO HOLD ONTO SOME SLIGHT CHANCE TO CHANCE POPS FOR THE FIRST HOUR OR TWO. A RELATIVE LULL IN THE CONVECTION CHANCES WILL OCCUR FROM THE EVENING INTO THE OVERNIGHT HOURS WITH THE LOSS OF DAYTIME HEATING AND IN ADVANCE OF THE SHORTWAVE TROUGH AND COLD FRONT. HOWEVER... SOME STRAY CONVECTION CANNOT BE COMPLETELY RULED OUT OVERNIGHT. ALSO...DEPENDING ON THE DEGREE OF CLEARING PATCHY FOG SHOULD ALSO DEVELOP...ESPECIALLY IN LOCATIONS THAT RECEIVED RAIN TODAY. THE AIRMASS REMAINS VERY MOIST AND WINDS ARE EXPECTED TO BE ON THE LIGHT SIDE. ON SATURDAY...THE CHANCES FOR CONVECTION WILL INCREASE ACROSS THE AREA AS THE COLD FRONT DROPS SOUTHEAST INTO THE REGION DURING THE MORNING. WITH SOME HEATING OF THE MOIST AIRMASS...SHOWERS AND THUNDERSTORMS NEAR THE BOUNDARY AND IN ADVANCE OF THE SHORTWAVE SHOULD BECOME RATHER NUMEROUS. CHANCES WILL BE THE HIGHEST IN THE NORTHWEST PART OF THE AREA FROM THE LATE MORNING INTO EARLY AFTERNOON AND THEN DURING THE AFTERNOON TO EARLY EVENING ACROSS THE REMAINDER OF THE REGION. THERE WILL BE PLENTY OF MOISTURE STILL IN PLACE FOR THE SHORTWAVE AND FRONT TO WORK WITH AND STORM MOTIONS WILL NOT BE ALL THAT HIGH. LOCALLY HEAVY RAIN WILL BE A THREAT FROM THESE. IF THERE IS AN AREA... POSSIBLY THE EASTERN OR SOUTHEASTERN PART OF THE AREA THAT GETS QUITE A BIT OF SUNSHINE IN THE MORNING...THEN A STRONG STORM OR TWO WITH STRONG WIND GUSTS WOULD ALSO BE POSSIBLE. THIS HAS BEEN HIGHLIGHTED IN THE HWO. CLOUDS AND THE THREAT FOR SHOWERS OR SOME LIGHT RAIN WILL LINGER INTO SATURDAY NIGHT...ESPECIALLY ACROSS THE SOUTHEAST. THUNDERSTORM CHANCES WILL ALSO DIMINISH BY LATE IN THE EVENING AS THE ATMOSPHERE STABILIZES. PLENTY OF LOW LEVEL MOISTURE AND LOW CLOUDS AND POSSIBLY STRATUS BUILD DOWN FOG WILL LINGER BEHIND THE BOUNDARY INTO SATURDAY NIGHT...AND CLOUD COVER SHOULD BE MOSTLY CLOUDY TO CLOUDY. LOW TEMPERATURES ON SATURDAY NIGHT WILL BE COLDER THAN RECENT NIGHTS...BUT RATHER CLOSE TO NORMAL. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 300 PM EDT FRI SEP 5 2014 THERE IS GOOD MODEL AGREEMENT ON THE OVERALL PATTERN CHANGE IN STORE FOR LATE NEXT WEEK...WITH MUCH COOLER AIR INVADING THE AREA AS COOL CANADIAN SURFACE HIGH PRESSURE INVADES THE PLAINS IN THE WAKE OF A COLD FRONT. HOWEVER...THE DAY TO DAY DETAILS AND TIMING OF EVENTS IS VERY UNCERTAIN...AND THERE CONTINUES TO BE LOW CONFIDENCE IN THE SPECIFICS OF THE FORECAST FOR NEXT WEEK. THE STANDARD MODEL BLEND LOAD HELPS TO TAKE INTO ACCOUNT THE VARIOUS MODEL DIFFERENCES...AND FOLLOWING THIS IDEA LEADS TO A CONTINUATION OF SHOWER AND THUNDERSTORM CHANCES FOR EVERY DAY NEXT WEEK. AFTER THE INITIAL COOL DOWN LATE THIS WEEKEND...TEMPERATURES WILL REBOUND AGAIN. THE BIG TEMPERATURE CHANGES BEING ADVERTISED WILL HAVE TO WAIT UNTIL THE END OF THIS FORECAST PERIOD AND BEYOND. IN ANY CASE A MORE FALL LIKE PATTERN WITH BELOW NORMAL TEMPERATURES IS IN STORE JUST BEYOND THE RANGE OF THIS FORECAST. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 737 PM EDT FRI SEP 5 2014 AFTER THE DISSIPATION OF AFTERNOON CONVECTION ACROSS EASTERN KY...EXPECT VFR CONDITIONS TO PREVAIL THROUGH THE EVENING. DEVELOPMENT OF VALLEY FOG IS AGAIN ANTICIPATED GENERALLY AFTER 4 TO 6Z...LIFTING AND DISSIPATING BY ABOUT 13Z. ATTM...VIS IS EXPECTED TO FALL INTO THE MVFR RANGE AT THE TAF SITES...PENDING THE DEGREE OF CLEARING...BUT SOME IFR VIS COULD OCCUR. GIVEN THE UNCERTAINTY IN WIDESPREAD DENSE FOG DEVELOPMENT FOR AN EXTENDED PERIOD OF TIME...DUE TO THE APPROACHING FRONTAL ZONE AND IMPINGING CLOUD COVER...DECIDED TO GO WITH A TEMPO FOR ANY IFR CONDITIONS. MORE THAN LIKELY... TAF SITES MAY EXPERIENCE JUMPS IN AND OUT OF IFR LATE TONIGHT/NEAR DAWN. A SHRA OR TSRA CANNOT BE RULED OUT AFTER 8Z OR 9Z...ESPECIALLY IN THE FAR NW...BUT HIGHER CHANCES SHOULD HOLD OFF UNTIL AT LEAST 13/14Z ACROSS THE TAF SITES. HIGH PROBABILITIES OF CONVECTION WILL OCCUR ALONG THE FRONTAL PASSAGE...SO WENT WITH PREVAILING TSRA AND LOWER CIGS STARTING AT 16Z AT THE FARTHEST NW SITE /KSME/...AND 19Z AT THE EASTERN MOST SITE /KSJS/ TO MATCH UP WITH ONGOING LIKELY POPS IN THE FORECAST. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...JP LONG TERM...SBH AVIATION...JMW
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
149 PM EDT THU SEP 4 2014 .UPDATE... ISSUED AT 1255 PM EDT THU SEP 4 2014 HOURLY GRIDS WERE UPDATED BASED ON RECENT OBSERVATIONS AND MODEL TRENDS. THE RECENT HRRR RUNS HAVE A DECENT HANDLE ON THE SCENARIO AT THIS TIME. POPS WERE RAISED ACROSS MUCH OF THE CWA MOSTLY INTO THE SCATTERED CATEGORY...WITH ISOLATED POPS INTRODUCED ACROSS THE BLUEGRASS COUNTIES. THE MOISTURE RETURN NORTH HAS BROUGHT A PLUME OF DEEP MOISTURE WITH PW OF 1.8 INCHES OR MORE INTO THE KY/TN/VA TRI STATE AREA...THOUGH PW IS GENERALLY 1.5 INCHES OR MORE ACROSS MOST OF THE CWA. ANY THUNDERSTORMS THIS AFTERNOON WILL BE CAPABLE OF LOCALLY HEAVY DOWNPOURS...AND IF THEY PERSIST SOME LOCALLY HEAVY RAINFALL. SO FAR THE HEAVIEST RAINFALL HAS FALLEN FROM MORE PERSISTENT SHOWERS AND THUNDERSTORMS IN PARTS OF THE CUMBERLAND VALLEY REGION. SHOWERS AND THUNDERSTORMS SHOULD PEAK IN COVERAGE LATER THIS AFTERNOON AND EARLY THIS EVENING AND THEN WANE TOWARD SUNSET...AS THE UPPER LEVEL DISTURBANCE MOVING ACROSS THE OH VALLEY REGION BEGINS TO DEPART TO THE NORTH AND EAST AND THE DEEPEST MOISTURE IS ALSO SHUNTED TO THE EAST AND SOUTHEAST OF THE REGION. UPDATE ISSUED AT 1019 AM EDT THU SEP 4 2014 HOURLY GRIDS HAVE BEEN UPDATED BASED ON RECENT OBSERVATIONS AND TRENDS. A FRESH ZFP WAS ALSO ISSUED TO GET RID OF MORNING FOG WORDING AS SATELLITE IMAGERY AND OBSERVATIONS INDICATE THAT VALLEY FOG CONTINUES TO LIFT. THE FOG HAS LIFTED INTO A STRATUS DECK IN SOME RIVER VALLEY LOCATIONS AND NEAR A FEW AREA LAKES...THIS ALSO IS GRADUALLY ERODING AWAY. RATHER LIGHT SOUTHWESTERLY FLOW WILL BRING INCREASING MOISTURE TO THE AREA BELOW 500 MB. THERE IS ALSO A SHORTWAVE TROUGH OR WEAKNESS BETWEEN RIDGING CENTERED NEAR BERMUDA AND ACROSS THE SOUTHEASTERN STATES AND ANOTHER UPPER LEVEL RIDGE CENTERED IN THE MS VALLEY REGION. THIS SHORTWAVE WILL WORK ACROSS THE REGION TODAY AND INTO THIS EVENING. THE COMBINATION OF CURRENT RATHER STRONG SFC HEATING AND THE INCREASING MOISTURE ALONG WITH THE WEAK SHORTWAVE TO MOVE ACROSS THE AREA SHOULD BRING ISOLATED TO SCATTERED CONVECTION TO PARTS OF THE REGION FROM MIDDAY INTO THE EVENING HOURS. THE CHANCES FOR CONVECTION STILL APPEAR TO BE HIGHEST NEAR THE VA BORDER WITH DEEPER MOISTURE THERE. UPDATE ISSUED AT 758 AM EDT THU SEP 4 2014 HAVE UPDATED THE FORECAST GRIDS BASED ON LATEST OBS...BUT WITH NO SUBSTANTIAL EFFECT ON THE OVERALL FORECAST. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 352 AM EDT THU SEP 4 2014 LIGHT WINDS...CLEAR TO PARTLY CLOUDY SKIES...AND A MOIST AIR MASS HAVE ALLOWED TYPICAL SEASONAL VALLEY FOG TO DEVELOP EARLY THIS MORNING. IT WILL DISSIPATE DURING THE MORNING...BUT GO THROUGH ITS CYCLE AGAIN TONIGHT/FRIDAY. SOMEWHAT DRIER AIR MADE IT INTO THE FAR NORTHERN PART OF THE FORECAST AREA ON WEDNESDAY AFTERNOON...BUT WILL NOT GET ANY FURTHER SOUTH. LOW LEVEL FLOW WILL CARRY MOISTURE NORTH AND NORTHEAST...ENSURING ALL AREAS ARE UNCOMFORTABLY HUMID TODAY THROUGH FRIDAY. THE HUMIDITY MAY FUEL DEVELOPMENT OF A FEW SHOWERS AND THUNDERSTORMS EACH AFTERNOON. THE GREATEST PROBABILITY WILL BE NEAR THE VA BORDER...WHERE MOISTURE WILL BE THE DEEPEST. FURTHER NW...FORECAST SOUNDINGS SHOW THE MOISTURE BEING MORE SHALLOW...WITH DRY AIR ALOFT BEING LESS SUPPORTIVE OF SUSTAINED CONVECTION IN THE ABSENCE OF DYNAMIC SUPPORT. IN ADDITION...WARMER MID LEVEL TEMPS IN OUR NW COUNTIES WILL ALSO MAKE IT MORE DIFFICULT TO GET DEEP CONVECTION THIS AFTERNOON. WINDS ALOFT WILL BE WEAK THROUGH THE PERIOD...AND LITTLE ORGANIZATION OF CONVECTION IS EXPECTED...HELPING TO LIMIT COVERAGE. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 352 AM EDT THU SEP 4 2014 BIG WEATHER CHANGE STILL ANTICIPATED THIS COMING WEEKEND AS MODELS REMAIN IN FAIRLY GOOD AGREEMENT. THE ONLY CHANGE WAS THAT MODELS HAVE SLOWED DOWN THE COLD FRONT A TAD...WHICH COULD NOW IMPACT THE FORECAST FOR SUNDAY. STARTING OFF THE PERIOD...DIURNALLY DRIVEN CONVECTION WILL DIE OFF EARLY FRIDAY EVENING...LEAVING DRY CONDITIONS FOR MUCH OF THE AREA THROUGH THE OVERNIGHT HOURS. THE EXPECTED COLD FRONT WILL MARCH INTO NORTHERN KENTUCKY BY MIDDAY SATURDAY AND SWING SOUTH THROUGH THE AFTERNOON AND EVENING HOURS. THIS WILL YIELD WIDESPREAD SHOWERS AND THUNDERSTORMS. HOWEVER...WITH THE MODELS SLOWING DOWN THE FRONT...LOOKS LIKE PRECIPITATION COULD LINGER INTO SATURDAY NIGHT AND EVEN INTO SUNDAY BEFORE ENDING LATE IN THE DAY ON SUNDAY. INSTABILITY SHOULD STILL DROP OFF OVERNIGHT SATURDAY NIGHT...SO THUNDER CHANCES WILL DIMINISH...BUT RAIN SHOWERS MAY PERSIST. THIS COULD SET UP A BIT WETTER AND CERTAINLY CLOUDIER SUNDAY FOR THOSE ACROSS THE SOUTH AND SOUTHEAST. REGARDLESS...HIGHS WILL ONLY REACH THE LOW TO MID 70S WITH THE ADDED CLOUD COVER AND COLD ADVECTION BEHIND THE FRONT. SUNDAY NIGHT WILL BE MUCH COOLER AS TEMPERATURES INTO THE 50S ARE EXPECTED. WHILE HIGH PRESSURE WILL BEGIN TO BUILD OVER THE AREA EARLY NEXT WEEK...SOME MOISTURE WILL REMAIN OVER EASTERN KENTUCKY...SUPPORTING AN ISOLATED SHOWER OR TWO. HOWEVER...INSTABILITY IS WEAK...AND FLOW ON MONDAY MAY BE FROM A SOUTHEAST DIRECTION...LEADING TO DOWNSLOPING...WHICH COULD SQUASH ANYTHING FROM FORMING. FOR NOW...WILL GO WITH A 20 POP TO COVER THE SMALL CHANCE. MODELS START DIVERGING QUITE A BIT AND HAVE STARTING TO FLIP FLOP ON VARIOUS SOLUTIONS AS WE HEAD TOWARDS TUESDAY. AT THIS TIME...OPTING TO KEEP EACH DAYTIME PERIOD WITH LOW POPS WITH LOWER COVERAGE AT NIGHT UNTIL WE SEE BETTER AGREEMENT WITH OUR NEXT WEATHER MAKER. THUS...CONFIDENCE IN THE FORECAST BEYOND MONDAY IS VERY LOW. IT DOES LOOK LIKE TEMPERATURES SHOULD REBOUND A BIT AS WE HEAD THROUGH NEXT WEEK...BUT THE EXTREME WARMTH SHOULD STAY AWAY FOR A LITTLE WHILE. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 140 PM EDT THU SEP 4 2014 SCATTERED TO NUMEROUS SHOWERS AND SOME THUNDERSTORMS WITH REDUCTIONS TO MVFR WILL WORK ACROSS THE TAF SITES DURING THE FIRST 6 HOURS OF THE PERIOD. THE MOST LIKELY STATIONS TO EXPERIENCE A THUNDERSTORM THROUGH 19Z ARE LOZ AND SME. HOWEVER...VCTS WAS CARRIED AT JKL AND SJS FOR THE FIRST 4 HOURS OF THE PERIOD. MOISTURE WILL DECREASE AS THE ASSOCIATED UPPER LEVEL DISTURBANCE BEGINS TO DEPART AND WITH LOSS OF DAYTIME HEATING...CONVECTION SHOULD WANE BY SUNSET. FOG WILL DEVELOP IN VALLEYS...GENERALLY AFTER 5Z AND PROBABLY AFFECT ALL THE TAF SITES THROUGH 14Z. WITH RAIN HAVING FALLEN AND THE LOW LEVELS REMAINING MOIST...THIS FOG MAY REDUCE VIS BELOW AIRPORT MINS AT ALL SITES FOR A TIME TOWARD DAWN. THE FOG SHOULD LIFT AND DISSIPATE BY 14Z...WITH VFR FROM THEN UNTIL THE END OF THE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...HAL LONG TERM...KAS AVIATION...JP
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
102 PM EDT THU SEP 4 2014 .UPDATE... ISSUED AT 1255 PM EDT THU SEP 4 2014 HOURLY GRIDS WERE UPDATED BASED ON RECENT OBSERVATIONS AND MODEL TRENDS. THE RECENT HRRR RUNS HAVE A DECENT HANDLE ON THE SCENARIO AT THIS TIME. POPS WERE RAISED ACROSS MUCH OF THE CWA MOSTLY INTO THE SCATTERED CATEGORY...WITH ISOLATED POPS INTRODUCED ACROSS THE BLUEGRASS COUNTIES. THE MOISTURE RETURN NORTH HAS BROUGHT A PLUME OF DEEP MOISTURE WITH PW OF 1.8 INCHES OR MORE INTO THE KY/TN/VA TRI STATE AREA...THOUGH PW IS GENERALLY 1.5 INCHES OR MORE ACROSS MOST OF THE CWA. ANY THUNDERSTORMS THIS AFTERNOON WILL BE CAPABLE OF LOCALLY HEAVY DOWNPOURS...AND IF THEY PERSIST SOME LOCALLY HEAVY RAINFALL. SO FAR THE HEAVIEST RAINFALL HAS FALLEN FROM MORE PERSISTENT SHOWERS AND THUNDERSTORMS IN PARTS OF THE CUMBERLAND VALLEY REGION. SHOWERS AND THUNDERSTORMS SHOULD PEAK IN COVERAGE LATER THIS AFTERNOON AND EARLY THIS EVENING AND THEN WANE TOWARD SUNSET...AS THE UPPER LEVEL DISTURBANCE MOVING ACROSS THE OH VALLEY REGION BEGINS TO DEPART TO THE NORTH AND EAST AND THE DEEPEST MOISTURE IS ALSO SHUNTED TO THE EAST AND SOUTHEAST OF THE REGION. UPDATE ISSUED AT 1019 AM EDT THU SEP 4 2014 HOURLY GRIDS HAVE BEEN UPDATED BASED ON RECENT OBSERVATIONS AND TRENDS. A FRESH ZFP WAS ALSO ISSUED TO GET RID OF MORNING FOG WORDING AS SATELLITE IMAGERY AND OBSERVATIONS INDICATE THAT VALLEY FOG CONTINUES TO LIFT. THE FOG HAS LIFTED INTO A STRATUS DECK IN SOME RIVER VALLEY LOCATIONS AND NEAR A FEW AREA LAKES...THIS ALSO IS GRADUALLY ERODING AWAY. RATHER LIGHT SOUTHWESTERLY FLOW WILL BRING INCREASING MOISTURE TO THE AREA BELOW 500 MB. THERE IS ALSO A SHORTWAVE TROUGH OR WEAKNESS BETWEEN RIDGING CENTERED NEAR BERMUDA AND ACROSS THE SOUTHEASTERN STATES AND ANOTHER UPPER LEVEL RIDGE CENTERED IN THE MS VALLEY REGION. THIS SHORTWAVE WILL WORK ACROSS THE REGION TODAY AND INTO THIS EVENING. THE COMBINATION OF CURRENT RATHER STRONG SFC HEATING AND THE INCREASING MOISTURE ALONG WITH THE WEAK SHORTWAVE TO MOVE ACROSS THE AREA SHOULD BRING ISOLATED TO SCATTERED CONVECTION TO PARTS OF THE REGION FROM MIDDAY INTO THE EVENING HOURS. THE CHANCES FOR CONVECTION STILL APPEAR TO BE HIGHEST NEAR THE VA BORDER WITH DEEPER MOISTURE THERE. UPDATE ISSUED AT 758 AM EDT THU SEP 4 2014 HAVE UPDATED THE FORECAST GRIDS BASED ON LATEST OBS...BUT WITH NO SUBSTANTIAL EFFECT ON THE OVERALL FORECAST. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 352 AM EDT THU SEP 4 2014 LIGHT WINDS...CLEAR TO PARTLY CLOUDY SKIES...AND A MOIST AIR MASS HAVE ALLOWED TYPICAL SEASONAL VALLEY FOG TO DEVELOP EARLY THIS MORNING. IT WILL DISSIPATE DURING THE MORNING...BUT GO THROUGH ITS CYCLE AGAIN TONIGHT/FRIDAY. SOMEWHAT DRIER AIR MADE IT INTO THE FAR NORTHERN PART OF THE FORECAST AREA ON WEDNESDAY AFTERNOON...BUT WILL NOT GET ANY FURTHER SOUTH. LOW LEVEL FLOW WILL CARRY MOISTURE NORTH AND NORTHEAST...ENSURING ALL AREAS ARE UNCOMFORTABLY HUMID TODAY THROUGH FRIDAY. THE HUMIDITY MAY FUEL DEVELOPMENT OF A FEW SHOWERS AND THUNDERSTORMS EACH AFTERNOON. THE GREATEST PROBABILITY WILL BE NEAR THE VA BORDER...WHERE MOISTURE WILL BE THE DEEPEST. FURTHER NW...FORECAST SOUNDINGS SHOW THE MOISTURE BEING MORE SHALLOW...WITH DRY AIR ALOFT BEING LESS SUPPORTIVE OF SUSTAINED CONVECTION IN THE ABSENCE OF DYNAMIC SUPPORT. IN ADDITION...WARMER MID LEVEL TEMPS IN OUR NW COUNTIES WILL ALSO MAKE IT MORE DIFFICULT TO GET DEEP CONVECTION THIS AFTERNOON. WINDS ALOFT WILL BE WEAK THROUGH THE PERIOD...AND LITTLE ORGANIZATION OF CONVECTION IS EXPECTED...HELPING TO LIMIT COVERAGE. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 352 AM EDT THU SEP 4 2014 BIG WEATHER CHANGE STILL ANTICIPATED THIS COMING WEEKEND AS MODELS REMAIN IN FAIRLY GOOD AGREEMENT. THE ONLY CHANGE WAS THAT MODELS HAVE SLOWED DOWN THE COLD FRONT A TAD...WHICH COULD NOW IMPACT THE FORECAST FOR SUNDAY. STARTING OFF THE PERIOD...DIURNALLY DRIVEN CONVECTION WILL DIE OFF EARLY FRIDAY EVENING...LEAVING DRY CONDITIONS FOR MUCH OF THE AREA THROUGH THE OVERNIGHT HOURS. THE EXPECTED COLD FRONT WILL MARCH INTO NORTHERN KENTUCKY BY MIDDAY SATURDAY AND SWING SOUTH THROUGH THE AFTERNOON AND EVENING HOURS. THIS WILL YIELD WIDESPREAD SHOWERS AND THUNDERSTORMS. HOWEVER...WITH THE MODELS SLOWING DOWN THE FRONT...LOOKS LIKE PRECIPITATION COULD LINGER INTO SATURDAY NIGHT AND EVEN INTO SUNDAY BEFORE ENDING LATE IN THE DAY ON SUNDAY. INSTABILITY SHOULD STILL DROP OFF OVERNIGHT SATURDAY NIGHT...SO THUNDER CHANCES WILL DIMINISH...BUT RAIN SHOWERS MAY PERSIST. THIS COULD SET UP A BIT WETTER AND CERTAINLY CLOUDIER SUNDAY FOR THOSE ACROSS THE SOUTH AND SOUTHEAST. REGARDLESS...HIGHS WILL ONLY REACH THE LOW TO MID 70S WITH THE ADDED CLOUD COVER AND COLD ADVECTION BEHIND THE FRONT. SUNDAY NIGHT WILL BE MUCH COOLER AS TEMPERATURES INTO THE 50S ARE EXPECTED. WHILE HIGH PRESSURE WILL BEGIN TO BUILD OVER THE AREA EARLY NEXT WEEK...SOME MOISTURE WILL REMAIN OVER EASTERN KENTUCKY...SUPPORTING AN ISOLATED SHOWER OR TWO. HOWEVER...INSTABILITY IS WEAK...AND FLOW ON MONDAY MAY BE FROM A SOUTHEAST DIRECTION...LEADING TO DOWNSLOPING...WHICH COULD SQUASH ANYTHING FROM FORMING. FOR NOW...WILL GO WITH A 20 POP TO COVER THE SMALL CHANCE. MODELS START DIVERGING QUITE A BIT AND HAVE STARTING TO FLIP FLOP ON VARIOUS SOLUTIONS AS WE HEAD TOWARDS TUESDAY. AT THIS TIME...OPTING TO KEEP EACH DAYTIME PERIOD WITH LOW POPS WITH LOWER COVERAGE AT NIGHT UNTIL WE SEE BETTER AGREEMENT WITH OUR NEXT WEATHER MAKER. THUS...CONFIDENCE IN THE FORECAST BEYOND MONDAY IS VERY LOW. IT DOES LOOK LIKE TEMPERATURES SHOULD REBOUND A BIT AS WE HEAD THROUGH NEXT WEEK...BUT THE EXTREME WARMTH SHOULD STAY AWAY FOR A LITTLE WHILE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 758 AM EDT THU SEP 4 2014 FOG WAS EXTENSIVE IN THE VALLEYS WITH RIVERS OR LARGE STREAMS...AND HAD CREPT OUT OF OUT TO SOME OF THE OPEN TERRAIN AND RIDGES. TAF SITES HAVE BEEN HIGHLY VARIABLE. THE FOG WILL DISSIPATE BY LATE THIS MORNING...LEAVING MOSTLY VFR THROUGH THE REST OF THE PERIOD. THERE MAY BE SOME SHOWERS OR THUNDERSTORMS DURING THE AFTERNOON...BUT THEY WILL BE SPARSE. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...HAL LONG TERM...KAS AVIATION...HAL
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
357 PM EDT THU SEP 4 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 518 AM EDT THU SEP 4 2014 AS FIGURED IT HAS BEEN A FAIRLY ACTIVE NIGHT AT LEAST IN TERMS OF SHRA/TSRA. NO SEVERE WEATHER IN OUR CWA...WITH BULK OF TSRA STAYING MAINLY OVER SOUTHERN CWA EARLIER TONIGHT. VERY HEAVY RAIN DID OCCUR EARLIER AS KIMT AND KMNM BOTH ENDED UP WITH AROUND AN INCH OF RAIN IN 45-60 MIN. STRONGEST STORMS IN THE AREA NOW ARE CROSSING CNTRL LK MICHIGAN. A LULL HAS DEVELOPED OVER UPR MICHIGAN...EXCEPT VERY FAR EAST WHERE RAIN AND EMBEDDED TSRA WILL RUN ITS COURSE OVER NEXT COUPLE HOURS. WESTERLY FLOW ALOFT AND THE MAIN SHORTWAVE IS DRIVING ACROSS SOUTHERN SASKATCHEWAN AND INTO WESTERN NORTH DAKOTA. SPC MESOANALYSIS PAGE SHOWS ISOLD-SCT STRONG-SEVERE STORMS OVER NORTH DAKOTA ARE FORMING IN WARM AIR ADVECTION REGION ALONG AND NORTH OF GRADIENT OF 1-6KM MUCAPE OF 2000-3000 J/KG MAXIMIZED FM SOUTHERN TO CENTRAL PLAINS. ACTIVITY IS ALSO JUST NORTH OF THE +12C ISOTHERM AT H7. CONVECTIVELY INDUCED WAVE IS ALSO FORMING OVR NORTH DAKOTA PER WV LOOP AND REGIONAL RADAR LOOPS. HIGH RES MODELS...SUCH AS THE HRRR AND NSSL WRF AND WRF-ARW/NMM BEGAN TO PICK UP ON THIS LATE WED EVENING AND CONTINUE TO INDICATE THIS MCV WITH ASSOCIATED MCS WILL CONTINUE TRACKING EAST ALONG MUCAPE/H85 DWPNT GRADIENT AND WITH THE H85-H3 WEST TO EAST ORIENTED THICKNESS LINES AND FOLLOWING THE FORWARD PROPAGATING CORFIDI VECTORS. CERTAINLY POSSIBLE THIS COMPLEX MAY GROW UPSCALE/PRODUCE WIDESPREAD SEVERE WX GIVEN THE SUFFICIENT EFFECTIVE SHEAR OVER 40 KTS PRESENT FM DAKOTAS ACROSS MINNESOTA AND ALSO DUE TO THE FAVORABLE 0-3KM SHEAR OVER 30 KTS THAT WOULD HELP THE SHEAR/COLD POOL BALANCE NEEDED TO SUSTAIN SUCH A COMPLEX. SFC WARM FRONT STILL WELL TO THE SOUTHWEST OF HERE THIS MORNING...MOST LIKELY OVER SOUTHERN MINNESOTA TO SOUTHWEST WISCONSIN. SEEMS THAT THIS COMPLEX WOULD HAVE TO TAKE A VERY HARD TURN RIGHT...AND QUICKLY FOR IT TO NOT IMPACT UPR GREAT LAKES LATER THIS MORNING OR MAYBE NOW AS LATEST HRRR SHOWS...EARLY AFTN. THE LATER ARRIVAL OF A COMPLEX... ALSO A GREATER SEVERE THREAT FOR WIND/HAIL OVER OUR CWA. CONFIDENCE IS NOT HIGH ENOUGH TO PUT SEVERE MENTION IN GRIDS...BUT WILL CONTINUE TO MENTION IN HWO AND VARIOUS SOCIAL MEDIA. UNFORTUNATELY...SINCE THIS AREA OF TSRA IS A NEW DEVELOPMENT COMPARED TO EXPECTED SHRA/TSRA EVOLUTION FOR TODAY LOOKED LIKE 12-24 HR AGO HAD TO REWORK POPS/WX CONSIDERABLY THROUGH MID AFTN TODAY. WHATEVER COMPLEX WORKS ACROSS UPR MICHIGAN SHOULD BE ON THE WANE AFT 18Z-21Z. WARM FRONT PROBABLY WILL HAVE TOUGH TIME MAKING IT TO THE CWA TODAY GIVEN THE SHRA/TSRA THAT WENT THROUGH OVERNIGHT AND THIS ADDITIONAL AREA OF TSRA POSSIBLE LATER TODAY. CAPPING THAT LOOKED SO FIERCE FOR THIS AFTN 24 HR AGO...NOW NOT AS MUCH... POSSIBLY BECAUSE THE ATMOSPHERE WILL BE WORKED OVER FROM SHRA/TSRA MOVING IN FM NORTH DAKOTA LATER TODAY. THUS...THINK THAT THE H85 MOISTURE TRANSPORT INTO AN AREA OF MID-LEVEL FGEN WILL BE ENOUGH TO REDEVELOP SHRA/TSRA OVER WESTERN CWA BY LATE THIS AFTN. ADDITIONAL POTENTIAL FOR SEVERE WITH THIS ACTIVITY AS WELL GIVEN MLCAPES AROUND 1500 J/KG AND EFFECTIVE SHEAR 40-55 KTS. SUPERCELL STRUCTURES WOULD STILL BE POSSIBLE WITH RIGHT MOVING SUPERCELLS SHOWING A WEST-EAST MOTION WHILE LEFT MOVERS WOULD MOVE MORE SOUTHWEST TO NORTHEAST. MEAN STORM MOTION WOULD BE WEST SOUTHWEST TO EAST NORTHEAST. ALL MOTIONS ARE SWIFT...PROBABLY IN THE 30-40 MPH RANGE. IN REGARDS TO SPECIFIC SEVERE POTENTIAL...SPC HAS OUR AREA FIRMLY IN THE 15 PCT RISK FOR SEVERE HAIL AND DAMAGING WINDS. THIS COULD OCCUR WITH THIS INITIAL COMPLEX IF IT MAKES INTO THE AREA. LIKELY DAMAGING WINDS WOULD BE THE MAIN THREAT IF THAT OCCURS. IF ADDITIONAL STORMS CAN REDEVELOP IN WAKE OF THIS ACTIVITY LATE THIS AFTN/EARLY THIS EVENING AHEAD OF STRONG COLD FRONT...THE DEGREE OF SHEAR INDICATES SUPERCELLS WOULD BE POSSIBLE ESPECIALLY IF MLCAPES RECOVER TOWARD 1500-2000 J/KG. ALL SEVERE MODES COULD OCCUR LATE THIS AFTN IF THAT OCCURS...EVEN POTENTIAL FOR TORNADOES AS 0-1KM SHEAR IS OVER 30 KTS AND ML LCL/S HEIGHTS WOULD BE VERY FAVORABLE AT LESS THAN 1000M. FREEZING LEVELS MAINLY BLO 13KFT AND MODELS INDICATE WOULD HAVE TO SEE CORES GET TO 30-35KFT FOR QUARTER SIZED HAIL. THIS SEEMS VERY ACHIEVABLE GIVEN THE SHEAR AND INSTABILITY FORECAST. THE WILD CARD IS EXTENT OF INSTABILITY THAT WILL BE LEFT IN WAKE OF THE INITIAL COMPLEX. MODELS COULD BE OVERPLAYING THAT...AND THUS THE ADDITIONAL SEVERE THREAT. TIME WILL TELL. LARGER SCALE FORCING IN TERMS OF SHORTWAVE AND DEEP LAYER LIFT SWINGS ACROSS THE CWA FM WEST TO EAST AND EXPECT SCT-NMRS SHOWERS AND TSRA IN THE EVENING. MAY BE AT LEAST SOME LINGERING RISK OF STRONGER STORMS DURING THIS TIME. DRYING PUNCHES IN IN MID-LEVELS OVERNIGHT AND COLD FRONT ARRIVES. EXPECT SHRA/TSRA CHANCES TO BE WANING OVER THE EAST CWA AFTER 08Z. FINALLY...GRADIENT WINDS WILL BE VERY GUSTY...FIRST OVER NORTHERN LK MICHIGAN TODAY IN THE SOUTH-SOUTHWEST FLOW...THEN LATE TONIGHT OVER LK SUPERIOR IN WAKE OF THE FRONT WHEN WINDS SHIFT TO THE WEST NORTHWEST. ISALLOBARIC ADDITION TO THE WIND COULD LEAD TO MARGINAL GALES IN BOTH OF THESE AREAS...AT LEAST FOR A FEW HOURS. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 357 PM EDT THU SEP 4 2014 NAM SHOWS A BROAD 500 MB TROUGH OVER THE NORTHERN PLAINS AND UPPER GREAT LAKES 00Z SAT. THIS TROUGH MOVES THROUGH FRI NIGHT. LOOKS QUIET THIS FORECAST PERIOD WITH A SHORTWAVE MOVING BY WELL NORTH OF US FRI NIGHT AND SAT. WILL NOT MAKE TOO MANY CHANGES TO THE GOING FORECAST FOR TEMPERATURES OR WEATHER. IN THE EXTENDED...GFS AND ECMWF SHOW A BROAD 500 MB RIDGE ACROSS THE SOUTHERN HALF OF THE U.S. WITH BROAD TROUGHING ACROSS THE NORTHERN HALF OF THE U.S. 12Z MON. THERE IS A SHORTWAVE OVER THE NORTHERN PLAINS 12Z MON. THIS SHORTWAVE MOVES INTO THE UPPER GREAT LAKES 12Z TUE AND PASSES THROUGH THE AREA TUE NIGHT. MORE TROUGHING THEN SETS UP TO THE WEST FOR THU AS THE UPPER PATTERN BECOMES MORE AMPLIFIED. TEMPERATURES WILL COOL DOWN TO NEAR NORMAL FOR THIS FORECAST PERIOD. WILL REMAIN DRY INTO MONDAY WITH A SFC FRONT AFFECTING THE AREA THROUGH THU AND WILL KEEP IN SOME LOW CHANCE POPS FOR THIS FRONT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 149 PM EDT THU SEP 4 2014 VERY COMPLICATED SHORT TERM FORECAST FOR ALL SITES. GENERAL VFR CONDITIONS EXPECTED AT IWD AND SAW THROUGH LATE AFTERNOON...AND MVFR CONDITIONS AT CMX. A COLD FRONT WILL THEN BRING A ROUND OF SHOWERS AND THUNDERSTORMS FOR ALL SITES THIS EVENING. CONFIDENCE REMAINS LOW ON HOW WIDESPREAD COVERAGE WILL BE...BUT ANYTHING THAT DEVELOPS IS EXPECTED TO BE STRONG WITH POSSIBLE HAIL AND WIND GUSTS OVER 50KTS. DUE TO THE LACK OF CONFIDENCE IN TIMING...PROVIDED A FOUR HOUR WINDOW IN THE TAF...THOUGH DO NOT EXPECT CONVECTION TO LAST FOR MORE THAN AN HOUR OR TWO. GUSTY NW WINDS TO 25KTS FOR IWD AND SAW...AND 30KTS FOR CMX ARE EXPECTED BEHIND THE COLD FRONT LATE TONIGHT THROUGH FRIDAY MORNING. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 357 PM EDT THU SEP 4 2014 ONGOING SEICHE ON LAKE SUPERIOR FROM THUNDERSTORMS TODAY WILL CONTINUE TONIGHT WITH FLUCTUATIONS IN WATER LEVELS OF 1 TO 2 FEET CONTINUING THIS EVENING. IT WILL TAKE A WHILE TO DAMPEN OUT AND PROBABLY WILL CONTINUE FOR SEVERAL DAYS. A COLD FRONT MOVING EAST ACROSS LAKE SUPERIOR TONIGHT WILL BRING GUSTY WESTERLY WINDS TO 30KTS FRIDAY WITH A FEW GALE FORCE GUSTS ACROSS CENTRAL LAKE SUPERIOR. STRONGER WINDS AGAIN ARRIVE TUE NIGHT WITH EAST WINDS UP TO 25 KNOTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... COASTAL FLOOD WARNING UNTIL MIDNIGHT EDT TONIGHT FOR MIZ004>007. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...07 AVIATION...KLUBER MARINE...07
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
209 PM EDT THU SEP 4 2014 LATEST UPDATE... MESOSCALE DISCUSSION .MESOSCALE DISCUSSION... ISSUED AT 209 PM EDT THU SEP 4 2014 AN IMPRESSIVE LOOKING BOWING LINE OF THUNDERSTORMS WITH A HISTORY OF WIND DAMAGE AND LARGE HAIL REPORTS IS RACING EAST SOUTHEAST AROUND 55 MPH. THE CURRENT TRACK WOULD KEEP MOST OF THE STORM NEAR AND NORTH OF ROUTE 10. IT SHOULD BE NOTED THE STORMS HAVE MOVED AWAY FROM THE BEST INFLOW...DEEP LAYER SHEAR AND INSTABILITY. AS SUCH I WOULD EXPECT THE LINE TO WEAKEN AS IT MOVES ONSHORE IN BY 230 PM. EVEN SO THE SPC SREF SHOWS 35 TO 50 KNOTS OF EFFECT SHEAR OVER THE STORMS SO THIS LINE WILL NOT TOTALLY DISSIPATE. AS A RESULT I HAVE PUT LIKELY POPS OVER OUR NORTHERN ROW OF COUNTIES. I MAY HAVE INCREASE POPS ANOTHER ROW OF TWO SOUTH WITHIN THE NEXT HOUR. && .SYNOPSIS... ISSUED AT 330 AM EDT THU SEP 4 2014 AN ACTIVE WEATHER PATTERN IS TAKING SHAPE FROM TODAY THROUGH FRIDAY EVENING. A WARM FRONT WILL BRING CHANCES FOR SHOWERS AND STORMS ESPECIALLY THIS MORNING. ADDITIONAL SHOWERS AND STORMS ARE EXPECTED TONIGHT THROUGH FRIDAY. THE RAIN SHOULD END FROM NORTH TO SOUTH ACROSS SOUTHWEST LOWER MICHIGAN FRIDAY NIGHT AS A COLD FRONT DROPS SOUTH THROUGH THE REGION. LOCALLY HEAVY RAIN IS A DISTINCT POSSIBILITY. IT SHOULD BECOME QUITE WARM THIS AFTERNOON WITH READINGS RISING INTO THE MIDDLE TO UPPER 80S IN MANY LOCATIONS. A COOLER WEEKEND IS ANTICIPATED BEHIND THE COLD FRONT WITH HIGHS IN THE LOWER 70S. && .UPDATE... ISSUED AT 1152 AM EDT THU SEP 4 2014 I LOWERED THE FORECAST HIGH TEMPERATURES TO THE 80 TO 85 DEGREE RANGE AND RAISED THE POP TO NEAR CONDITIONAL INTO LATE MORNING. I THEN ALLOWED THE POP TO TAIL OFF TO BELOW 15 PCT BY MID AFTERNOON AS MORE STABLE AIR MOVES INTO THE AREA. OUR MCV THAT ROLLED THROUGH OUR CWA HAS CREATED A WAKE LOW FEATURE AND THE ENTIRE COMPLEX IS SINKING SOUTHEAST WITH TIME. THIS RESULTED IN SOME LOCALLY HIGH WINDS. MEANWHILE THE RAP MODEL SHOWS THE MCV TRACKING ESE INTO SE LOWER MICHIGAN/NORTHWEST OHIO BY MID AFTERNOON. MEANWHILE THERE IS STRONG PUSH OF HOT AIR AT MID LEVEL BEING ADVECTED IN BEHIND THE WARM FRONT. RAP MODEL SOUNDING SHOW THE AIR OVER SOUTHWEST LOWER MICHIGAN BECOMING VERY STABLE WITH CIN VALUES OVER 250 J/KG BY 00Z AS A RESULT OF THAT DEEP PUSH OF HOT AIR. THIS WILL END ALL PRECIPITATION BY EARLY AFTERNOON AND ALLOW THE SUN TO FINALLY COME OUT AND HEAT THE AIR. EVEN SO...GIVEN HOW CLOUDY IS IS NOW...HARD TO IMAGINE IT WILL GET MUCH WARMER THAN THE MID 80S... SO I LOWERED THE FORECAST HIGH FROM THE UPPER 80S TO THE MID 80S. THE LOW LEVEL JET SETS UP AGAIN TONIGHT BUT THE AXIS OF IT IS NORTH OF HTL. THE MOISTURE TRANSPORT VECTORS IN THE 1000/850 LAYER ARE MORE IMPRESSIVE TONIGHT THAN LAST NIGHT BUT THEY ARE FOCUSED NEAR TVC. GIVEN THE CAPE DUE TO THE WARM AIR ALOFT I HAVE TO WONDER HOW MUCH OF THE CONVECTION FROM WI/UPPER MICHIGAN WILL MAKE IT SOUTH INTO THE GRR CWA. WE WILL HAVE TO LOOK MORE CLOSELY AT THAT LATER. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 330 AM EDT THU SEP 4 2014 AREAL EXTENT AND TIMING OF THUNDERSTORMS IS THE BIGGEST CHALLENGE WITH THE FORECAST THIS MORNING. SHOWERS AND STORMS ARE CURRENTLY DEVELOPING TO OUR WEST IN A ZONE OF SOLID MOISTURE ADVECTION AT 850MB/S. THIS PUSH OF MOISTURE SURGES INTO THE AREA THIS MORNING AND WILL BRING THE CHANCE OF SHOWERS AND STORMS TO ALL AREAS. A BIT OF A LULL IS EXPECTED THIS AFTERNOON AS WE BREAK INTO THE WARM SECTOR OF THE SYSTEM. AT LEAST PARTIAL CLEARING SHOULD ALLOW TEMPERATURES TO PUSH WELL INTO THE 80S. GIVEN THE TIMING OF THE STORMS NOT EXPECTING SEVERE WEATHER THIS MORNING. THUNDERSTORMS SHOULD BECOME FAIRLY NUMEROUS AGAIN TONIGHT AS ANOTHER SURGE OF MOISTURE ADVECTS INTO SOUTHWEST LOWER MICHIGAN. GIVEN OVERNIGHT TIMING AGAIN...WE ARE NOT EXPECTING SEVERE WEATHER BUT IT IS NOT OUT OF THE REALM OF POSSIBILITIES. IN FACT WE ARE ON THE EASTERN EDGE OF A SLIGHT RISK AREA THAT CROSSES MASON INTO OCEANA COUNTY. WIND AND HAIL WOULD BE THE MAIN THREATS. FRIDAY INTO FRIDAY NIGHT...THE COLD FRONT PROGRESSES SOUTH THROUGH THE AREA. THE LLJ PEELS AWAY TO THE EAST FRIDAY...BUT WE COULD BE LOOKING AT STRONG DESTABILIZATION IN THE SOUTHERN HALF OF THE FORECAST AREA. THE INSTABILITY ALONE MAY BE ENOUGH TO GENERATE SOME SCATTERED SEVERE WEATHER. FEEL THE FRONT WILL AID IN FOCUSING STORMS AND LOCALLY HEAVY RAINFALL AS WELL. THE RAIN SHOULD GRADUALLY TAPER OFF FRIDAY EVENING FROM NORTH TO SOUTH. SATURDAY WILL BE A MAINLY SUNNY AND DRY DAY WITH HIGHS IN THE LOWER 70S. .LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 330 AM EDT THU SEP 4 2014 HIGH PRESSURE WILL BUILD IN TO BRING FAIR WEATHER WITH SEASONABLE TEMPERATURES THIS WEEKEND WITH MAX TEMPS RANGING FROM THE UPPER 60S TO MIDDLE 70S AND MIN TEMPS IN THE 40S TO LOWER 50S. SOME CLOUDS WILL BEGIN TO MOVE IN MONDAY AS SOUTHERLY FLOW DEVELOPS AND RESULTS IN GRADUALLY INCREASING MOISTURE ON THE BACK SIDE OF THE DEPARTING HIGH PRESSURE RIDGE. DRY WEATHER WILL CONTINUE MONDAY THROUGH MONDAY NIGHT. DEVELOPING LOW PRESSURE AND A WARM FRONT WILL BRING POTENTIAL FOR RAIN AND THUNDERSTORMS AS EARLY AS TUESDAY WITH A LITTLE BETTER CHANCE FOR PRECIPITATION TUESDAY NIGHT THROUGH WEDNESDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 754 AM EDT THU SEP 4 2014 AREA OF SHOWERS AND THUNDERSTORMS WILL WORK THROUGH THE TAF SITES THROUGH MIDDAY...ENDING FROM NORTHWEST (KMKG) TO SOUTHEAST (KJXN) BETWEEN 13Z AND 16Z OR SO. THE EXPECTATION IS THAT THE SHOWERS AND STORMS WILL TAPER OFF THIS MORNING WITH SKIES CLEARING OUT THIS AFTERNOON. MAINLY VFR CONDITIONS ARE IN PLACE WITH HIGH BASED STORMS OCCURRING. SOME BRIEF PERIODS OF MVFR CAN BE EXPECTED IN THE HEAVIER STORMS. VFR SHOULD PREVAIL THIS AFTERNOON AS WE TRY TO SCATTER OUT. WINDS WILL PICK UP THIS MORNING FROM THE SOUTH-SOUTHWEST AT 10-25 KNOTS. THE HIGHEST WINDS WILL BE SEEN AT KMKG. OVERNIGHT ANOTHER ROUND OF SHOWERS AND STORMS ARE EXPECTED TO WORK THROUGH THE TAF SITES...AFTER 04Z TO 06Z. CEILINGS AND VISIBILITIES MAY DIP INTO THE MVFR CATEGORY AGAIN...BUT AT THIS POINT JUST MENTIONED VCTS WORDING. && .MARINE... ISSUED AT 1152 AM EDT THU SEP 4 2014 BASED ON EARLIER MARINE OBSERVATIONS AS THE STORMS WERE MOVING THROUGH I EXPANDED THE SMALL CRAFT ADVISORY FARTHER SOUTH. THE PORT SHELDON BUOY AT 1120 AM STILL HAD GUSTS TO 29 KNOTS WITH 6 FOOT WAVES. SOUTH HAVEN AT GUSTS AS HIGH AS 33 KNOTS BUT THAT HAS SINCE DIMINISHED TO 15 TO 20 KNOTS. WEB CAMS FROM PORT SHELDON...GRAND HAVEN...AND MUSKEGON SHOW WHITE CAPS ON THE WATER WITH 4 TO 6 FOOT WAVES (BUOY DATA). SO BOTTOM LINE IT MAKES SENSE TO KEEP THE KEEP THE ADVISORY AND BEACH HAZARD STATEMENT GOING. && .HYDROLOGY... ISSUED AT 330 AM EDT THU SEP 4 2014 PERIODS OF THUNDERSTORMS ARE EXPECTED FROM THIS MORNING THROUGH FRIDAY EVENING. PWAT VALUES RISE INTO THE 1.50 TO 2.00 INCH RANGE AS SOUTHERLY FLOW STREAMS IN DEEP MOISTURE. THE DEEPEST MOISTURE LOOKS TO BE IN PLACE THURSDAY NIGHT THROUGH FRIDAY WHICH IS WHEN THE HEAVIEST RAINS WILL LIKELY FALL. RIVER LEVELS REMAIN WELL WITHIN BANK THOUGH...SO RIVER FLOODING IS NOT REALLY ANTICIPATED. SWATHS OF 1 TO 2 INCH RAINFALLS REMAIN A POSSIBILITY...ESPECIALLY ACROSS CENTRAL LOWER MICHIGAN AND POTENTIALLY ALONG I94. EVEN WITH THESE TOTALS WE ARE PROBABLY NOT LOOKING AT MUCH MORE THAN SOLID WITHIN BANK RISES. REGARDING LOCALIZED AREAL FLOODING FROM THE STORMS THEMSELVES...THIS REMAINS A POSSIBILITY AS WELL GIVEN THE DEEP MOISTURE IN PLACE. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...BEACH HAZARDS STATEMENT THROUGH FRIDAY MORNING FOR MIZ037-043- 050-056-064-071. LM...SMALL CRAFT ADVISORY UNTIL 11 AM EDT FRIDAY FOR LMZ844>849. && $$ MESOSCALE...WDM UPDATE...WDM SYNOPSIS...DUKE SHORT TERM...DUKE LONG TERM...LAURENS AVIATION...DUKE HYDROLOGY...DUKE MARINE...WDM
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
1154 AM EDT THU SEP 4 2014 LATEST UPDATE... UPDATE/MARINE .SYNOPSIS... ISSUED AT 330 AM EDT THU SEP 4 2014 AN ACTIVE WEATHER PATTERN IS TAKING SHAPE FROM TODAY THROUGH FRIDAY EVENING. A WARM FRONT WILL BRING CHANCES FOR SHOWERS AND STORMS ESPECIALLY THIS MORNING. ADDITIONAL SHOWERS AND STORMS ARE EXPECTED TONIGHT THROUGH FRIDAY. THE RAIN SHOULD END FROM NORTH TO SOUTH ACROSS SOUTHWEST LOWER MICHIGAN FRIDAY NIGHT AS A COLD FRONT DROPS SOUTH THROUGH THE REGION. LOCALLY HEAVY RAIN IS A DISTINCT POSSIBILITY. IT SHOULD BECOME QUITE WARM THIS AFTERNOON WITH READINGS RISING INTO THE MIDDLE TO UPPER 80S IN MANY LOCATIONS. A COOLER WEEKEND IS ANTICIPATED BEHIND THE COLD FRONT WITH HIGHS IN THE LOWER 70S. && .UPDATE... ISSUED AT 1152 AM EDT THU SEP 4 2014 I LOWERED THE FORECAST HIGH TEMPERATURES TO THE 80 TO 85 DEGREE RANGE AND RAISED THE POP TO NEAR CONDITIONAL INTO LATE MORNING. I THEN ALLOWED THE POP TO TAIL OFF TO BELOW 15 PCT BY MID AFTERNOON AS MORE STABLE AIR MOVES INTO THE AREA. OUR MCV THAT ROLLED THROUGH OUR CWA HAS CREATED A WAKE LOW FEATURE AND THE ENTIRE COMPLEX IS SINKING SOUTHEAST WITH TIME. THIS RESULTED IN SOME LOCALLY HIGH WINDS. MEANWHILE THE RAP MODEL SHOWS THE MCV TRACKING ESE INTO SE LOWER MICHIGAN/NORTHWEST OHIO BY MID AFTERNOON. MEANWHILE THERE IS STRONG PUSH OF HOT AIR AT MID LEVEL BEING ADVECTED IN BEHIND THE WARM FRONT. RAP MODEL SOUNDING SHOW THE AIR OVER SOUTHWEST LOWER MICHIGAN BECOMING VERY STABLE WITH CIN VALUES OVER 250 J/KG BY 00Z AS A RESULT OF THAT DEEP PUSH OF HOT AIR. THIS WILL END ALL PRECIPITATION BY EARLY AFTERNOON AND ALLOW THE SUN TO FINALLY COME OUT AND HEAT THE AIR. EVEN SO...GIVEN HOW CLOUDY IS IS NOW...HARD TO IMAGINE IT WILL GET MUCH WARMER THAN THE MID 80S... SO I LOWERED THE FORECAST HIGH FROM THE UPPER 80S TO THE MID 80S. THE LOW LEVEL JET SETS UP AGAIN TONIGHT BUT THE AXIS OF IT IS NORTH OF HTL. THE MOISTURE TRANSPORT VECTORS IN THE 1000/850 LAYER ARE MORE IMPRESSIVE TONIGHT THAN LAST NIGHT BUT THEY ARE FOCUSED NEAR TVC. GIVEN THE CAPE DUE TO THE WARM AIR ALOFT I HAVE TO WONDER HOW MUCH OF THE CONVECTION FROM WI/UPPER MICHIGAN WILL MAKE IT SOUTH INTO THE GRR CWA. WE WILL HAVE TO LOOK MORE CLOSELY AT THAT LATER. && .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 330 AM EDT THU SEP 4 2014 AREAL EXTENT AND TIMING OF THUNDERSTORMS IS THE BIGGEST CHALLENGE WITH THE FORECAST THIS MORNING. SHOWERS AND STORMS ARE CURRENTLY DEVELOPING TO OUR WEST IN A ZONE OF SOLID MOISTURE ADVECTION AT 850MB/S. THIS PUSH OF MOISTURE SURGES INTO THE AREA THIS MORNING AND WILL BRING THE CHANCE OF SHOWERS AND STORMS TO ALL AREAS. A BIT OF A LULL IS EXPECTED THIS AFTERNOON AS WE BREAK INTO THE WARM SECTOR OF THE SYSTEM. AT LEAST PARTIAL CLEARING SHOULD ALLOW TEMPERATURES TO PUSH WELL INTO THE 80S. GIVEN THE TIMING OF THE STORMS NOT EXPECTING SEVERE WEATHER THIS MORNING. THUNDERSTORMS SHOULD BECOME FAIRLY NUMEROUS AGAIN TONIGHT AS ANOTHER SURGE OF MOISTURE ADVECTS INTO SOUTHWEST LOWER MICHIGAN. GIVEN OVERNIGHT TIMING AGAIN...WE ARE NOT EXPECTING SEVERE WEATHER BUT IT IS NOT OUT OF THE REALM OF POSSIBILITIES. IN FACT WE ARE ON THE EASTERN EDGE OF A SLIGHT RISK AREA THAT CROSSES MASON INTO OCEANA COUNTY. WIND AND HAIL WOULD BE THE MAIN THREATS. FRIDAY INTO FRIDAY NIGHT...THE COLD FRONT PROGRESSES SOUTH THROUGH THE AREA. THE LLJ PEELS AWAY TO THE EAST FRIDAY...BUT WE COULD BE LOOKING AT STRONG DESTABILIZATION IN THE SOUTHERN HALF OF THE FORECAST AREA. THE INSTABILITY ALONE MAY BE ENOUGH TO GENERATE SOME SCATTERED SEVERE WEATHER. FEEL THE FRONT WILL AID IN FOCUSING STORMS AND LOCALLY HEAVY RAINFALL AS WELL. THE RAIN SHOULD GRADUALLY TAPER OFF FRIDAY EVENING FROM NORTH TO SOUTH. SATURDAY WILL BE A MAINLY SUNNY AND DRY DAY WITH HIGHS IN THE LOWER 70S. .LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 330 AM EDT THU SEP 4 2014 HIGH PRESSURE WILL BUILD IN TO BRING FAIR WEATHER WITH SEASONABLE TEMPERATURES THIS WEEKEND WITH MAX TEMPS RANGING FROM THE UPPER 60S TO MIDDLE 70S AND MIN TEMPS IN THE 40S TO LOWER 50S. SOME CLOUDS WILL BEGIN TO MOVE IN MONDAY AS SOUTHERLY FLOW DEVELOPS AND RESULTS IN GRADUALLY INCREASING MOISTURE ON THE BACK SIDE OF THE DEPARTING HIGH PRESSURE RIDGE. DRY WEATHER WILL CONTINUE MONDAY THROUGH MONDAY NIGHT. DEVELOPING LOW PRESSURE AND A WARM FRONT WILL BRING POTENTIAL FOR RAIN AND THUNDERSTORMS AS EARLY AS TUESDAY WITH A LITTLE BETTER CHANCE FOR PRECIPITATION TUESDAY NIGHT THROUGH WEDNESDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 754 AM EDT THU SEP 4 2014 AREA OF SHOWERS AND THUNDERSTORMS WILL WORK THROUGH THE TAF SITES THROUGH MIDDAY...ENDING FROM NORTHWEST (KMKG) TO SOUTHEAST (KJXN) BETWEEN 13Z AND 16Z OR SO. THE EXPECTATION IS THAT THE SHOWERS AND STORMS WILL TAPER OFF THIS MORNING WITH SKIES CLEARING OUT THIS AFTERNOON. MAINLY VFR CONDITIONS ARE IN PLACE WITH HIGH BASED STORMS OCCURRING. SOME BRIEF PERIODS OF MVFR CAN BE EXPECTED IN THE HEAVIER STORMS. VFR SHOULD PREVAIL THIS AFTERNOON AS WE TRY TO SCATTER OUT. WINDS WILL PICK UP THIS MORNING FROM THE SOUTH-SOUTHWEST AT 10-25 KNOTS. THE HIGHEST WINDS WILL BE SEEN AT KMKG. OVERNIGHT ANOTHER ROUND OF SHOWERS AND STORMS ARE EXPECTED TO WORK THROUGH THE TAF SITES...AFTER 04Z TO 06Z. CEILINGS AND VISIBILITIES MAY DIP INTO THE MVFR CATEGORY AGAIN...BUT AT THIS POINT JUST MENTIONED VCTS WORDING. && .MARINE... ISSUED AT 1152 AM EDT THU SEP 4 2014 BASED ON EARLIER MARINE OBSERVATIONS AS THE STORMS WERE MOVING THROUGH I EXPANDED THE SMALL CRAFT ADVISORY FARTHER SOUTH. THE PORT SHELDON BUOY AT 1120 AM STILL HAD GUSTS TO 29 KNOTS WITH 6 FOOT WAVES. SOUTH HAVEN AT GUSTS AS HIGH AS 33 KNOTS BUT THAT HAS SINCE DIMINISHED TO 15 TO 20 KNOTS. WEB CAMS FROM PORT SHELDON...GRAND HAVEN...AND MUSKEGON SHOW WHITE CAPS ON THE WATER WITH 4 TO 6 FOOT WAVES (BUOY DATA). SO BOTTOM LINE IT MAKES SENSE TO KEEP THE KEEP THE ADVISORY AND BEACH HAZARD STATEMENT GOING. && .HYDROLOGY... ISSUED AT 330 AM EDT THU SEP 4 2014 PERIODS OF THUNDERSTORMS ARE EXPECTED FROM THIS MORNING THROUGH FRIDAY EVENING. PWAT VALUES RISE INTO THE 1.50 TO 2.00 INCH RANGE AS SOUTHERLY FLOW STREAMS IN DEEP MOISTURE. THE DEEPEST MOISTURE LOOKS TO BE IN PLACE THURSDAY NIGHT THROUGH FRIDAY WHICH IS WHEN THE HEAVIEST RAINS WILL LIKELY FALL. RIVER LEVELS REMAIN WELL WITHIN BANK THOUGH...SO RIVER FLOODING IS NOT REALLY ANTICIPATED. SWATHS OF 1 TO 2 INCH RAINFALLS REMAIN A POSSIBILITY...ESPECIALLY ACROSS CENTRAL LOWER MICHIGAN AND POTENTIALLY ALONG I94. EVEN WITH THESE TOTALS WE ARE PROBABLY NOT LOOKING AT MUCH MORE THAN SOLID WITHIN BANK RISES. REGARDING LOCALIZED AREAL FLOODING FROM THE STORMS THEMSELVES...THIS REMAINS A POSSIBILITY AS WELL GIVEN THE DEEP MOISTURE IN PLACE. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...BEACH HAZARDS STATEMENT THROUGH FRIDAY MORNING FOR MIZ037-043- 050-056-064-071. LM...SMALL CRAFT ADVISORY UNTIL 11 AM EDT FRIDAY FOR LMZ844>849. && $$ UPDATE...WDM SYNOPSIS...DUKE SHORT TERM...DUKE LONG TERM...LAURENS AVIATION...DUKE HYDROLOGY...DUKE MARINE...WDM
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
742 AM EDT THU SEP 4 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 518 AM EDT THU SEP 4 2014 AS FIGURED IT HAS BEEN A FAIRLY ACTIVE NIGHT AT LEAST IN TERMS OF SHRA/TSRA. NO SEVERE WEATHER IN OUR CWA...WITH BULK OF TSRA STAYING MAINLY OVER SOUTHERN CWA EARLIER TONIGHT. VERY HEAVY RAIN DID OCCUR EARLIER AS KIMT AND KMNM BOTH ENDED UP WITH AROUND AN INCH OF RAIN IN 45-60 MIN. STRONGEST STORMS IN THE AREA NOW ARE CROSSING CNTRL LK MICHIGAN. A LULL HAS DEVELOPED OVER UPR MICHIGAN...EXCEPT VERY FAR EAST WHERE RAIN AND EMBEDDED TSRA WILL RUN ITS COURSE OVER NEXT COUPLE HOURS. WESTERLY FLOW ALOFT AND THE MAIN SHORTWAVE IS DRIVING ACROSS SOUTHERN SASKATCHEWAN AND INTO WESTERN NORTH DAKOTA. SPC MESOANALYSIS PAGE SHOWS ISOLD-SCT STRONG-SEVERE STORMS OVER NORTH DAKOTA ARE FORMING IN WARM AIR ADVECTION REGION ALONG AND NORTH OF GRADIENT OF 1-6KM MUCAPE OF 2000-3000 J/KG MAXIMIZED FM SOUTHERN TO CENTRAL PLAINS. ACTIVITY IS ALSO JUST NORTH OF THE +12C ISOTHERM AT H7. CONVECTIVELY INDUCED WAVE IS ALSO FORMING OVR NORTH DAKOTA PER WV LOOP AND REGIONAL RADAR LOOPS. HIGH RES MODELS...SUCH AS THE HRRR AND NSSL WRF AND WRF-ARW/NMM BEGAN TO PICK UP ON THIS LATE WED EVENING AND CONTINUE TO INDICATE THIS MCV WITH ASSOCIATED MCS WILL CONTINUE TRACKING EAST ALONG MUCAPE/H85 DWPNT GRADIENT AND WITH THE H85-H3 WEST TO EAST ORIENTED THICKNESS LINES AND FOLLOWING THE FORWARD PROPAGATING CORFIDI VECTORS. CERTAINLY POSSIBLE THIS COMPLEX MAY GROW UPSCALE/PRODUCE WIDESPREAD SEVERE WX GIVEN THE SUFFICIENT EFFECTIVE SHEAR OVER 40 KTS PRESENT FM DAKOTAS ACROSS MINNESOTA AND ALSO DUE TO THE FAVORABLE 0-3KM SHEAR OVER 30 KTS THAT WOULD HELP THE SHEAR/COLD POOL BALANCE NEEDED TO SUSTAIN SUCH A COMPLEX. SFC WARM FRONT STILL WELL TO THE SOUTHWEST OF HERE THIS MORNING...MOST LIKELY OVER SOUTHERN MINNESOTA TO SOUTHWEST WISCONSIN. SEEMS THAT THIS COMPLEX WOULD HAVE TO TAKE A VERY HARD TURN RIGHT...AND QUICKLY FOR IT TO NOT IMPACT UPR GREAT LAKES LATER THIS MORNING OR MAYBE NOW AS LATEST HRRR SHOWS...EARLY AFTN. THE LATER ARRIVAL OF A COMPLEX... ALSO A GREATER SEVERE THREAT FOR WIND/HAIL OVER OUR CWA. CONFIDENCE IS NOT HIGH ENOUGH TO PUT SEVERE MENTION IN GRIDS...BUT WILL CONTINUE TO MENTION IN HWO AND VARIOUS SOCIAL MEDIA. UNFORTUNATELY...SINCE THIS AREA OF TSRA IS A NEW DEVELOPMENT COMPARED TO EXPECTED SHRA/TSRA EVOLUTION FOR TODAY LOOKED LIKE 12-24 HR AGO HAD TO REWORK POPS/WX CONSIDERABLY THROUGH MID AFTN TODAY. WHATEVER COMPLEX WORKS ACROSS UPR MICHIGAN SHOULD BE ON THE WANE AFT 18Z-21Z. WARM FRONT PROBABLY WILL HAVE TOUGH TIME MAKING IT TO THE CWA TODAY GIVEN THE SHRA/TSRA THAT WENT THROUGH OVERNIGHT AND THIS ADDITIONAL AREA OF TSRA POSSIBLE LATER TODAY. CAPPING THAT LOOKED SO FIERCE FOR THIS AFTN 24 HR AGO...NOW NOT AS MUCH... POSSIBLY BECAUSE THE ATMOSPHERE WILL BE WORKED OVER FROM SHRA/TSRA MOVING IN FM NORTH DAKOTA LATER TODAY. THUS...THINK THAT THE H85 MOISTURE TRANSPORT INTO AN AREA OF MID-LEVEL FGEN WILL BE ENOUGH TO REDEVELOP SHRA/TSRA OVER WESTERN CWA BY LATE THIS AFTN. ADDITIONAL POTENTIAL FOR SEVERE WITH THIS ACTIVITY AS WELL GIVEN MLCAPES AROUND 1500 J/KG AND EFFECTIVE SHEAR 40-55 KTS. SUPERCELL STRUCTURES WOULD STILL BE POSSIBLE WITH RIGHT MOVING SUPERCELLS SHOWING A WEST-EAST MOTION WHILE LEFT MOVERS WOULD MOVE MORE SOUTHWEST TO NORTHEAST. MEAN STORM MOTION WOULD BE WEST SOUTHWEST TO EAST NORTHEAST. ALL MOTIONS ARE SWIFT...PROBABLY IN THE 30-40 MPH RANGE. IN REGARDS TO SPECIFIC SEVERE POTENTIAL...SPC HAS OUR AREA FIRMLY IN THE 15 PCT RISK FOR SEVERE HAIL AND DAMAGING WINDS. THIS COULD OCCUR WITH THIS INITIAL COMPLEX IF IT MAKES INTO THE AREA. LIKELY DAMAGING WINDS WOULD BE THE MAIN THREAT IF THAT OCCURS. IF ADDITIONAL STORMS CAN REDEVELOP IN WAKE OF THIS ACTIVITY LATE THIS AFTN/EARLY THIS EVENING AHEAD OF STRONG COLD FRONT...THE DEGREE OF SHEAR INDICATES SUPERCELLS WOULD BE POSSIBLE ESPECIALLY IF MLCAPES RECOVER TOWARD 1500-2000 J/KG. ALL SEVERE MODES COULD OCCUR LATE THIS AFTN IF THAT OCCURS...EVEN POTENTIAL FOR TORNADOES AS 0-1KM SHEAR IS OVER 30 KTS AND ML LCL/S HEIGHTS WOULD BE VERY FAVORABLE AT LESS THAN 1000M. FREEZING LEVELS MAINLY BLO 13KFT AND MODELS INDICATE WOULD HAVE TO SEE CORES GET TO 30-35KFT FOR QUARTER SIZED HAIL. THIS SEEMS VERY ACHIEVABLE GIVEN THE SHEAR AND INSTABILITY FORECAST. THE WILD CARD IS EXTENT OF INSTABILITY THAT WILL BE LEFT IN WAKE OF THE INITIAL COMPLEX. MODELS COULD BE OVERPLAYING THAT...AND THUS THE ADDITIONAL SEVERE THREAT. TIME WILL TELL. LARGER SCALE FORCING IN TERMS OF SHORTWAVE AND DEEP LAYER LIFT SWINGS ACROSS THE CWA FM WEST TO EAST AND EXPECT SCT-NMRS SHOWERS AND TSRA IN THE EVENING. MAY BE AT LEAST SOME LINGERING RISK OF STRONGER STORMS DURING THIS TIME. DRYING PUNCHES IN IN MID-LEVELS OVERNIGHT AND COLD FRONT ARRIVES. EXPECT SHRA/TSRA CHANCES TO BE WANING OVER THE EAST CWA AFTER 08Z. FINALLY...GRADIENT WINDS WILL BE VERY GUSTY...FIRST OVER NORTHERN LK MICHIGAN TODAY IN THE SOUTH-SOUTHWEST FLOW...THEN LATE TONIGHT OVER LK SUPERIOR IN WAKE OF THE FRONT WHEN WINDS SHIFT TO THE WEST NORTHWEST. ISALLOBARIC ADDITION TO THE WIND COULD LEAD TO MARGINAL GALES IN BOTH OF THESE AREAS...AT LEAST FOR A FEW HOURS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 451 AM EDT THU SEP 4 2014 FRI...EXPECT ANY LINGERING SHRA/TSRA OVER THE FAR ERN CWA TO DEPART BY MID MORNING. OTHERWISE...CAA DROPPING 850 MB TEMPS INTO THE 6C-8C RANGE WILL KEEP MAX READINGS IN THE LOWER 60S WEST TO AROUND 70 NEAR LAKE MICHIGAN. AS THE STRONG LOW OVER NRN ONTARIO LIFTS NE INTO NRN QUEBEC AND HIGH PRESSURE OVER THE PLAINS BUILDS INTO THE WRN GREAT LAKES...GUSTY WNW WINDS WILL GRADUALLY DIMINISH. HOWEVER...WINDS GUSTING TO AROUND 30 KNOTS MAY BE POSSIBLE EARLY OVER THE KEWEENAW...ESPECIALLY FOR THE WEST FACING HIGHER TERRAIN. FRI NIGHT INTO SUNDAY...DRY WEATHER IS EXPECTED TO PREVAIL AS THE REGION REMAINS UNDER THE INFLUENCE OF HIGH PRESSURE THAT GRADUALLY BUILDS INTO THE SRN GREAT LAKE. PCPN ASSOCIATED WITH SHRTWVS MOVING THROUGH NRN ONTARIO BOTH FRI NIGHT AND SAT NIGHT SHOULD REMAIN NORTH OF LAKE SUPERIOR GIVEN THE DRY AIRMASS OVER THE REGION. THE MAIN IMPACT ON UPPER MI WILL BE TO REINFORCE THE SEASONABLY COOL AIR. MON-WED...THE GFS/GEFS AND ECWMF WERE IN GENERAL AGREEMENT THAT THE ZONAL PATTERN MONDAY WILL GIVE WAY TO TROUGHING INTO THE NRN PLAINS SHIFTING TOWARD THE UPPER MS VALLEY. THERE ARE DIFFERENCES IN HANDLING THE DETAILS OF THE TIMING/STRENGTH OF THE PLAINS TROUGH AND A MORE DOMINANT LOW NEAR HUDSON BAY. WITH BOTH THE MID LEVEL AND SFC TROUGH APPROACHING THE AREA...PCPN CHANCES WILL INCREASE FROM TUE INTO WED. HOWEVER...PCPN AMOUNTS WILL GENERALLY BE LIGHT WITH ONLY A SLIGHT CHANCE FOR TSRA...MAINLY ON TUE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 741 AM EDT THU SEP 4 2014 LOW CLOUDS HAVE EXPANDED BEHIND THE DEPARTING AREA OF SHRA/TSRA OVER THE UPPER LAKES THIS MORNING. LIFR CONDITIONS AT KIWD/KSAW WILL GRADUALLY BECOME MVFR BUT THIS MAY TAKE UNTIL LATE MORNING. BIGGER CONCERN...AT LEAST FOR KIWD IS COMPLEX OF STRONG TO SEVERE STORMS ROLLING EAST ACROSS MINNESOTA. CHANCES ARE INCREASING THAT AT LEAST REMNANT OF TSRA WILL SURVIVE TO KIWD. ADDED TSRA IN THE TAFS AND WENT WITH MVFR VSBY FOR NOW. RAIN COULD FALL HEAVY WHEN TSRA MOVE THROUGH. SOME CHANCE OF WIND GUSTS OVER 40 KTS AS WELL...THOUGH NOT ENOUGH CONFIDENCE TO INCLUDE IN TAF. AT KCMX MAY SEE SHRA WITH EMBEDDED TSRA LATE MORNING INTO EARLY AFTN...AND IF THIS WHOLE COMPLEX HOLDS TOGETHER IT WOULD REACH KSAW EARLY AFTN AS WELL. ONCE THIS LEADING COMPLEX OF TSRA IS THROUGH...ATTN TURNS TO APPROACHING COLD FRONT AS THIS MAY TRIGGER ISOLD/SCT STRONG TO SVR TSTMS LATER THIS AFTN/EVENING. CONFIDENCE IN DEVELOPMENT IS STILL VERY LOW AT THIS POINT. INCLUDED VCSH MENTION WITH THE FROPA...BUT ONLY OPTED FOR TSRA MENTION AT KSAW AS THAT IS WHERE MODEL FCST GUIDANCE SUGGESTS A BETTER POTENTIAL FOR TSRA. WINDS BECOME GUSTY LATE TONIGHT AT KCMX IN WAKE OF THE FRONT WITH GUSTS OVER 30 KTS POSSIBLE. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 511 AM EDT THU SEP 4 2014 A LOW PRESSURE SYSTEM OVER THE EASTERN DAKOTAS WILL LIFT TO THE NORTHEAST THROUGH NRN MN TODAY AND TO JAMES BAY BY FRIDAY MORNING. MOIST AIR MOVING OVER THE LAKE UNDER SOUTHEASTERLY WINDS WILL LEAD TO PATCHY/AREAS OF FOG OVER PORTIONS OF THE LAKE TONIGHT THROUGH FRIDAY MORNING. A COLD FRONT MOVING EAST ACROSS LAKE SUPERIOR TONIGHT WILL BRING GUSTY WESTERLY WINDS TO 30KTS THROUGH FRIDAY MORNING. WINDS WILL DIMINISH FRIDAY AFTERNOON/NIGHT AS A HIGH PRESSURE RIDGE BUILDS OVER THE UPPER GREAT LAKES REGION. THIS WILL LEAD TO LIGHT WINDS THROUGH THE WEEKEND AND THE FIRST PART OF NEXT WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...JLB AVIATION...JLA MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
522 AM EDT THU SEP 4 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 518 AM EDT THU SEP 4 2014 AS FIGURED IT HAS BEEN A FAIRLY ACTIVE NIGHT AT LEAST IN TERMS OF SHRA/TSRA. NO SEVERE WEATHER IN OUR CWA...WITH BULK OF TSRA STAYING MAINLY OVER SOUTHERN CWA EARLIER TONIGHT. VERY HEAVY RAIN DID OCCUR EARLIER AS KIMT AND KMNM BOTH ENDED UP WITH AROUND AN INCH OF RAIN IN 45-60 MIN. STRONGEST STORMS IN THE AREA NOW ARE CROSSING CNTRL LK MICHIGAN. A LULL HAS DEVELOPED OVER UPR MICHIGAN...EXCEPT VERY FAR EAST WHERE RAIN AND EMBEDDED TSRA WILL RUN ITS COURSE OVER NEXT COUPLE HOURS. WESTERLY FLOW ALOFT AND THE MAIN SHORTWAVE IS DRIVING ACROSS SOUTHERN SASKATCHEWAN AND INTO WESTERN NORTH DAKOTA. SPC MESOANALYSIS PAGE SHOWS ISOLD-SCT STRONG-SEVERE STORMS OVER NORTH DAKOTA ARE FORMING IN WARM AIR ADVECTION REGION ALONG AND NORTH OF GRADIENT OF 1-6KM MUCAPE OF 2000-3000 J/KG MAXIMIZED FM SOUTHERN TO CENTRAL PLAINS. ACTIVITY IS ALSO JUST NORTH OF THE +12C ISOTHERM AT H7. CONVECTIVELY INDUCED WAVE IS ALSO FORMING OVR NORTH DAKOTA PER WV LOOP AND REGIONAL RADAR LOOPS. HIGH RES MODELS...SUCH AS THE HRRR AND NSSL WRF AND WRF-ARW/NMM BEGAN TO PICK UP ON THIS LATE WED EVENING AND CONTINUE TO INDICATE THIS MCV WITH ASSOCIATED MCS WILL CONTINUE TRACKING EAST ALONG MUCAPE/H85 DWPNT GRADIENT AND WITH THE H85-H3 WEST TO EAST ORIENTED THICKNESS LINES AND FOLLOWING THE FORWARD PROPAGATING CORFIDI VECTORS. CERTAINLY POSSIBLE THIS COMPLEX MAY GROW UPSCALE/PRODUCE WIDESPREAD SEVERE WX GIVEN THE SUFFICIENT EFFECTIVE SHEAR OVER 40 KTS PRESENT FM DAKOTAS ACROSS MINNESOTA AND ALSO DUE TO THE FAVORABLE 0-3KM SHEAR OVER 30 KTS THAT WOULD HELP THE SHEAR/COLD POOL BALANCE NEEDED TO SUSTAIN SUCH A COMPLEX. SFC WARM FRONT STILL WELL TO THE SOUTHWEST OF HERE THIS MORNING...MOST LIKELY OVER SOUTHERN MINNESOTA TO SOUTHWEST WISCONSIN. SEEMS THAT THIS COMPLEX WOULD HAVE TO TAKE A VERY HARD TURN RIGHT...AND QUICKLY FOR IT TO NOT IMPACT UPR GREAT LAKES LATER THIS MORNING OR MAYBE NOW AS LATEST HRRR SHOWS...EARLY AFTN. THE LATER ARRIVAL OF A COMPLEX... ALSO A GREATER SEVERE THREAT FOR WIND/HAIL OVER OUR CWA. CONFIDENCE IS NOT HIGH ENOUGH TO PUT SEVERE MENTION IN GRIDS...BUT WILL CONTINUE TO MENTION IN HWO AND VARIOUS SOCIAL MEDIA. UNFORTUNATELY...SINCE THIS AREA OF TSRA IS A NEW DEVELOPMENT COMPARED TO EXPECTED SHRA/TSRA EVOLUTION FOR TODAY LOOKED LIKE 12-24 HR AGO HAD TO REWORK POPS/WX CONSIDERABLY THROUGH MID AFTN TODAY. WHATEVER COMPLEX WORKS ACROSS UPR MICHIGAN SHOULD BE ON THE WANE AFT 18Z-21Z. WARM FRONT PROBABLY WILL HAVE TOUGH TIME MAKING IT TO THE CWA TODAY GIVEN THE SHRA/TSRA THAT WENT THROUGH OVERNIGHT AND THIS ADDITIONAL AREA OF TSRA POSSIBLE LATER TODAY. CAPPING THAT LOOKED SO FIERCE FOR THIS AFTN 24 HR AGO...NOW NOT AS MUCH... POSSIBLY BECAUSE THE ATMOSPHERE WILL BE WORKED OVER FROM SHRA/TSRA MOVING IN FM NORTH DAKOTA LATER TODAY. THUS...THINK THAT THE H85 MOISTURE TRANSPORT INTO AN AREA OF MID-LEVEL FGEN WILL BE ENOUGH TO REDEVELOP SHRA/TSRA OVER WESTERN CWA BY LATE THIS AFTN. ADDITIONAL POTENTIAL FOR SEVERE WITH THIS ACTIVITY AS WELL GIVEN MLCAPES AROUND 1500 J/KG AND EFFECTIVE SHEAR 40-55 KTS. SUPERCELL STRUCTURES WOULD STILL BE POSSIBLE WITH RIGHT MOVING SUPERCELLS SHOWING A WEST-EAST MOTION WHILE LEFT MOVERS WOULD MOVE MORE SOUTHWEST TO NORTHEAST. MEAN STORM MOTION WOULD BE WEST SOUTHWEST TO EAST NORTHEAST. ALL MOTIONS ARE SWIFT...PROBABLY IN THE 30-40 MPH RANGE. IN REGARDS TO SPECIFIC SEVERE POTENTIAL...SPC HAS OUR AREA FIRMLY IN THE 15 PCT RISK FOR SEVERE HAIL AND DAMAGING WINDS. THIS COULD OCCUR WITH THIS INITIAL COMPLEX IF IT MAKES INTO THE AREA. LIKELY DAMAGING WINDS WOULD BE THE MAIN THREAT IF THAT OCCURS. IF ADDITIONAL STORMS CAN REDEVELOP IN WAKE OF THIS ACTIVITY LATE THIS AFTN/EARLY THIS EVENING AHEAD OF STRONG COLD FRONT...THE DEGREE OF SHEAR INDICATES SUPERCELLS WOULD BE POSSIBLE ESPECIALLY IF MLCAPES RECOVER TOWARD 1500-2000 J/KG. ALL SEVERE MODES COULD OCCUR LATE THIS AFTN IF THAT OCCURS...EVEN POTENTIAL FOR TORNADOES AS 0-1KM SHEAR IS OVER 30 KTS AND ML LCL/S HEIGHTS WOULD BE VERY FAVORABLE AT LESS THAN 1000M. FREEZING LEVELS MAINLY BLO 13KFT AND MODELS INDICATE WOULD HAVE TO SEE CORES GET TO 30-35KFT FOR QUARTER SIZED HAIL. THIS SEEMS VERY ACHIEVABLE GIVEN THE SHEAR AND INSTABILITY FORECAST. THE WILD CARD IS EXTENT OF INSTABILITY THAT WILL BE LEFT IN WAKE OF THE INITIAL COMPLEX. MODELS COULD BE OVERPLAYING THAT...AND THUS THE ADDITIONAL SEVERE THREAT. TIME WILL TELL. LARGER SCALE FORCING IN TERMS OF SHORTWAVE AND DEEP LAYER LIFT SWINGS ACROSS THE CWA FM WEST TO EAST AND EXPECT SCT-NMRS SHOWERS AND TSRA IN THE EVENING. MAY BE AT LEAST SOME LINGERING RISK OF STRONGER STORMS DURING THIS TIME. DRYING PUNCHES IN IN MID-LEVELS OVERNIGHT AND COLD FRONT ARRIVES. EXPECT SHRA/TSRA CHANCES TO BE WANING OVER THE EAST CWA AFTER 08Z. FINALLY...GRADIENT WINDS WILL BE VERY GUSTY...FIRST OVER NORTHERN LK MICHIGAN TODAY IN THE SOUTH-SOUTHWEST FLOW...THEN LATE TONIGHT OVER LK SUPERIOR IN WAKE OF THE FRONT WHEN WINDS SHIFT TO THE WEST NORTHWEST. ISALLOBARIC ADDITION TO THE WIND COULD LEAD TO MARGINAL GALES IN BOTH OF THESE AREAS...AT LEAST FOR A FEW HOURS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 451 AM EDT THU SEP 4 2014 FRI...EXPECT ANY LINGERING SHRA/TSRA OVER THE FAR ERN CWA TO DEPART BY MID MORNING. OTHERWISE...CAA DROPPING 850 MB TEMPS INTO THE 6C-8C RANGE WILL KEEP MAX READINGS IN THE LOWER 60S WEST TO AROUND 70 NEAR LAKE MICHIGAN. AS THE STRONG LOW OVER NRN ONTARIO LIFTS NE INTO NRN QUEBEC AND HIGH PRESSURE OVER THE PLAINS BUILDS INTO THE WRN GREAT LAKES...GUSTY WNW WINDS WILL GRADUALLY DIMINISH. HOWEVER...WINDS GUSTING TO AROUND 30 KNOTS MAY BE POSSIBLE EARLY OVER THE KEWEENAW...ESPECIALLY FOR THE WEST FACING HIGHER TERRAIN. FRI NIGHT INTO SUNDAY...DRY WEATHER IS EXPECTED TO PREVAIL AS THE REGION REMAINS UNDER THE INFLUENCE OF HIGH PRESSURE THAT GRADUALLY BUILDS INTO THE SRN GREAT LAKE. PCPN ASSOCIATED WITH SHRTWVS MOVING THROUGH NRN ONTARIO BOTH FRI NIGHT AND SAT NIGHT SHOULD REMAIN NORTH OF LAKE SUPERIOR GIVEN THE DRY AIRMASS OVER THE REGION. THE MAIN IMPACT ON UPPER MI WILL BE TO REINFORCE THE SEASONABLY COOL AIR. MON-WED...THE GFS/GEFS AND ECWMF WERE IN GENERAL AGREEMENT THAT THE ZONAL PATTERN MONDAY WILL GIVE WAY TO TROUGHING INTO THE NRN PLAINS SHIFTING TOWARD THE UPPER MS VALLEY. THERE ARE DIFFERENCES IN HANDLING THE DETAILS OF THE TIMING/STRENGTH OF THE PLAINS TROUGH AND A MORE DOMINANT LOW NEAR HUDSON BAY. WITH BOTH THE MID LEVEL AND SFC TROUGH APPROACHING THE AREA...PCPN CHANCES WILL INCREASE FROM TUE INTO WED. HOWEVER...PCPN AMOUNTS WILL GENERALLY BE LIGHT WITH ONLY A SLIGHT CHANCE FOR TSRA...MAINLY ON TUE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 133 AM EDT THU SEP 4 2014 SHRA THAT ARE MOVING ACROSS UPPER MI HAVE ALREADY MOVED E OF THE KIWD/KCMX AREAS AND WILL BE E OF KSAW IN THE NEXT HR OR TWO. VFR CONDITIONS WILL START THE FCST PERIOD...BUT TOWARD DAYBREAK AND INTO THE MORNING HRS...LOW CLOUDS MAY EXPAND NORTHWARD BEHIND THE DEPARTING AREA OF PCPN OVER THE UPPER LAKES. KEPT THE IDEA OF MVFR CIGS DEVELOPING AT ALL TERMINALS...BUT NOT OUT OF THE QUESTION THAT IFR COULD DEVELOP...MAINLY AT KSAW WHERE UPSLOPE WINDS WILL BE MORE FAVORABLE. LOWER CLOUDS SHOULD SCATTER OUT BY EARLY AFTN. MEANWHILE...SOME OF THE SHRA/TSTMS CURRENTLY OVER THE DAKOTAS MAY HOLD TOGETHER...BRINGING THE POTENTIAL FOR PCPN AT ALL THE TERMINALS MID MORNING TO EARLY AFTN. WITH LOW CONFIDENCE...ONLY INCLUDED A VCSH MENTION...BUT THIS MAY NEED MORE OF A MENTION FOR 12Z TAFS. THEN...APPROACHING COLD FRONT MAY TRIGGER ISOLD/SCT STRONG TO SVR TSTMS LATER THIS AFTN/EVENING...BUT CONFIDENCE IN DEVELOPMENT OF PCPN IS VERY LOW AT THIS POINT. MODEL FCST GUIDANCE SUGGESTS KSAW MAY HAVE A BETTER POTENTIAL FOR CONVECTION...SO ONLY OPTED FOR A VCTS MENTION AT THAT TERMINAL IN THE EVENING. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 511 AM EDT THU SEP 4 2014 A LOW PRESSURE SYSTEM OVER THE EASTERN DAKOTAS WILL LIFT TO THE NORTHEAST THROUGH NRN MN TODAY AND TO JAMES BAY BY FRIDAY MORNING. MOIST AIR MOVING OVER THE LAKE UNDER SOUTHEASTERLY WINDS WILL LEAD TO PATCHY/AREAS OF FOG OVER PORTIONS OF THE LAKE TONIGHT THROUGH FRIDAY MORNING. A COLD FRONT MOVING EAST ACROSS LAKE SUPERIOR TONIGHT WILL BRING GUSTY WESTERLY WINDS TO 30KTS THROUGH FRIDAY MORNING. WINDS WILL DIMINISH FRIDAY AFTERNOON/NIGHT AS A HIGH PRESSURE RIDGE BUILDS OVER THE UPPER GREAT LAKES REGION. THIS WILL LEAD TO LIGHT WINDS THROUGH THE WEEKEND AND THE FIRST PART OF NEXT WEEK. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLA LONG TERM...JLB AVIATION...ROLFSON MARINE...JLB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
108 PM CDT THU SEP 4 2014 .UPDATE... ISSUED AT 1250 PM CDT THU SEP 4 2014 UPDATED TO INCLUDE 18Z AVIATION DISCUSSION BELOW. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 325 AM CDT THU SEP 4 2014 MAIN CONCERNS WITH THIS PERIOD ARE THE FORWARD PROPAGATING MCS THAT IS EXPECTED TO DEVELOP AND RACE ACROSS CENTRAL MN EARLY THIS MORNING. THIS WILL BE FOLLOWED BY HOT AND HUMID TEMPERATURES ACROSS EASTERN MN AND WESTERN WI...WITH A FEW SHOWERS AND THUNDERSTORMS POSSIBLE BY LATE AFTERNOON. MEANWHILE A SEASONABLY STRONG COLD FRONT WILL PUSH THROUGH THE REGION AND BRING BREEZY NORTHWESTERLY WINDS OVERNIGHT ALONG WITH COOL/DRY AIR. THE FIRST ORDER OF DISCUSSION IS THE SEVERE WEATHER THREAT THIS MORNING RELATED TO THE CONVECTION ACROSS NORTH DAKOTA. HIRES MODELS SUCH AS THE HRRR AND 00/03Z RUNS OF THE HOPWRF ARE IN REMARKABLE AGREEMENT THAT THIS CONVECTION WILL INTENSIFY AS IT MOVES INTO WESTERN MINNESOTA AND DEVELOP INTO A BOW ECHO. THIS STORM MODE SEEM VERY PLAUSIBLE CONSIDERING THE ORIENTATION OF THE DEEP LAYER SHEAR VECTORS IN RELATION TO THE WARM FRONT AND MUCAPE GRADIENT...SO INCLUDED DAMAGING WINDS IN THE FORECAST ACROSS THE FAR NORTHERN TIER OF COUNTIES. THE HRRR SEEMS TO HAVE A BETTER HANDLE ON THE ONGOING CONVECTION...AND IT KEEPS THE MAJORITY OF THE FORECAST PRECIP NORTH OF THE CWA. HOWEVER BASED ON THE ACTUAL LOCATION OF THE WARM FRONT STILL THINK THERE IS LEGITIMATE RISK ALONG AND NORTH OF A LINE FROM ALEXANDRIA MN TO RICE LAKE WI. AS THE COLD POOL BECOMES WELL ESTABLISHED THIS CONVECTION WILL RACE EASTWARD. MEANWHILE THE UPPER LEVEL WAVE AND SURFACE LOW WILL SLOWLY MAKE THEIR WAY INTO NORTHERN MN ALLOWING THE WARM SECTOR TO DESTABILIZE THROUGHOUT THE DAY ON THURSDAY. DEPENDING ON THE RESIDUAL CLOUD COVER...AFTERNOON HIGH TEMPS COULD EASILY CLIMB INTO THE 90S ACROSS SOUTHEASTERN MN AND WESTERN WI. FOR NOW DID NOT GO MUCH ABOVE GUIDANCE SINCE SHOWERS AND THUNDERSTORMS COULD DEVELOP ALONG THE TRAILING COLD FRONT LIMITING THE DIABATIC HEATING. A FEW OF THESE STORMS ARE LIKELY TO BE SEVERE AS FORECAST SOUNDINGS SHOW NEARLY 4000J/KG OF CAPE BY LATE AFTERNOON AND AROUND 30KTS OF DEEP LAYER SHEAR ALONG AND EAST OF THE MN/WI BORDER. THIS AFOREMENTIONED COLD FRONT IS THE LAST REAL AREA OF INTEREST. AGAIN FORECAST SOUNDINGS SHOW STRONG COLD AIR ADVECTION IN THE WAKE OF THE FRONT. THIS WILL KEEP THE BOUNDARY LAYER WELL MIXED WITH NORTHWESTERLY WIND GUSTS OF 20 TO 30MPH EXPECTED TO PREVAIL AFTER DARK. THEREFORE INCREASED THE WINDS THURSDAY NIGHT...AND USED LESS BIAS-CORRECTED GRIDS FOR OVERNIGHT LOWS SINCE THE TEMPERATURES SHOULD BE RATHER UNIFORM. ALSO RAISED CLOUD COVER SINCE SOUNDINGS SHOW SATURATION ABOVE THE BOUNDARY LAYER. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 325 AM CDT THU SEP 4 2014 THE FIRST HALF OF THE LONG TERM LOOKS RATHER QUIET. THERE WILL BE A SPLIT FLOW PATTERN DEVELOPING WITH THE SUBTROPICAL JET TO THE SOUTH KEEPING THE HEAT CONFINED TO THE SOUTHERN STATES...AND THE POLAR JET ACROSS CENTRAL CANADA KEEPING THE UNSEASONABLY COOL AIR TO THE NORTH - AT LEAST FOR THE TIME BEING. SURFACE HIGH PRESSURE WILL GUARANTEE MOSTLY CLEAR SKIES THROUGH SUNDAY NIGHT. THINGS BECOME A BIT MORE COMPLEX NEXT WEEK AS THE POLAR JET BEGINS TO SINK SOUTH. A MORE ACTIVE PATTERN IS IN THE OFFING WITH SEVERAL DISTURBANCES SKIRTING ALONG THE NORTHERN TIER OF THE U.S. HOWEVER...WITH THE SUBTROPICAL JET REMAINING SOUTH IT DOES NOT APPEAR ANY OF THESE DISTURBANCES WILL HAVE A WHOLE LOT OF MOISTURE TO WORK WITH. THEREFORE KEPT POPS IN THE CHC RANGE. EVENTUALLY THE JETS WILL PHASE AND CARVE OUT A DEEP TROUGH OVER CANADA AND THE NORTHERN U.S. SOME TIME DURING THE MIDDLE OF NEXT WEEK. THE MUCH COOLER TEMPS ACCOMPANYING THIS TROUGH SHOULD MARK THE FIRST CRACK AT AUTUMN WEATHER. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1250 PM CDT THU SEP 4 2014 MAIN CONVECTION FROM THE MORNING HAS SHIFTED INTO THE GREAT LAKES REGION WHILE SCATTERED SHOWERS HAVE DEVELOPED THIS AFTN OVER MAINLY SWRN MN IN THE WAKE OF THE MORNING ACTIVITY. THIS IS IN RESPONSE TO THE CDFNT MAKING PROGRESS INTO WRN MN THIS AFTN AND MODEST INSTABILITY AND WEAK CAPPING REMAINING OVER MUCH OF MN. PRECIP COVERAGE LOOKS TO BE SCATTERED AT BEST...WITH POSSIBLY SOME ISOLD EMBEDDED TSTMS...BUT UNTIL TSTMS SHOW BETTER COVERAGE IT IS DIFFICULT TO ADVERTISE AS SUCH IN THE TAFS SO HAVE GONE MAINLY -SHRA WITH MVFR FLIGHT CONDS. CONDS IMPROVE THIS EVENING INTO THE OVERNIGHT HRS AS WINDS SHIFT TO W-NW AND DRIER AIR WORKS ITS WAY INTO THE AREA. SOME DISCREPANCIES EXIST AS TO THE COVERAGE AND HEIGHT OF CLOUDS OVERNIGHT THRU DAYBREAK...BUT HAVE OPTED TO GO MAINLY VFR OVERNIGHT THRU TMRW WITH NW FLOW DEVELOPING AND DRIER AIR MOVING IN. KMSP...WILL KEEP AN EYE OUT FOR POTENTIAL SCATTERED SHRA/TSTMS THIS AFTN...PARTICULARLY BETWEEN INITIALIZATION TIME AND 22Z AS THE ACTIVITY OVER SWRN MN SHIFTS NE. HAVE HELD OFF CB/TS MENTION ATTM AS CHCS ARE LOW FOR CONVECTION AND COVERAGE IS VERY ISOLD. WILL MONITOR AND AMEND AS NEEDED. OTHERWISE...CONDS IMPROVE THIS EVE THRU OVERNIGHT AND WILL REMAIN VFR TNGT AND TMRW. /OUTLOOK FOR KMSP/ SAT...VFR. WINDS W 5-10 KTS. SUN...VFR. WINDS SW 5-10 KTS. MON...MAINLY VFR. CHC MVFR IN SHRA/TSRA. WINDS S 10-15 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ UPDATE...JPC SHORT TERM...JRB LONG TERM...BORGHOFF AVIATION...JPC
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
609 AM CDT THU SEP 4 2014 .UPDATED FOR 12Z AVIATION DISCUSSION... ISSUED AT 552 AM CDT THU SEP 4 2014 && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 325 AM CDT THU SEP 4 2014 MAIN CONCERNS WITH THIS PERIOD ARE THE FORWARD PROPAGATING MCS THAT IS EXPECTED TO DEVELOP AND RACE ACROSS CENTRAL MN EARLY THIS MORNING. THIS WILL BE FOLLOWED BY HOT AND HUMID TEMPERATURES ACROSS EASTERN MN AND WESTERN WI...WITH A FEW SHOWERS AND THUNDERSTORMS POSSIBLE BY LATE AFTERNOON. MEANWHILE A SEASONABLY STRONG COLD FRONT WILL PUSH THROUGH THE REGION AND BRING BREEZY NORTHWESTERLY WINDS OVERNIGHT ALONG WITH COOL/DRY AIR. THE FIRST ORDER OF DISCUSSION IS THE SEVERE WEATHER THREAT THIS MORNING RELATED TO THE CONVECTION ACROSS NORTH DAKOTA. HIRES MODELS SUCH AS THE HRRR AND 00/03Z RUNS OF THE HOPWRF ARE IN REMARKABLE AGREEMENT THAT THIS CONVECTION WILL INTENSIFY AS IT MOVES INTO WESTERN MINNESOTA AND DEVELOP INTO A BOW ECHO. THIS STORM MODE SEEM VERY PLAUSIBLE CONSIDERING THE ORIENTATION OF THE DEEP LAYER SHEAR VECTORS IN RELATION TO THE WARM FRONT AND MUCAPE GRADIENT...SO INCLUDED DAMAGING WINDS IN THE FORECAST ACROSS THE FAR NORTHERN TIER OF COUNTIES. THE HRRR SEEMS TO HAVE A BETTER HANDLE ON THE ONGOING CONVECTION...AND IT KEEPS THE MAJORITY OF THE FORECAST PRECIP NORTH OF THE CWA. HOWEVER BASED ON THE ACTUAL LOCATION OF THE WARM FRONT STILL THINK THERE IS LEGITIMATE RISK ALONG AND NORTH OF A LINE FROM ALEXANDRIA MN TO RICE LAKE WI. AS THE COLD POOL BECOMES WELL ESTABLISHED THIS CONVECTION WILL RACE EASTWARD. MEANWHILE THE UPPER LEVEL WAVE AND SURFACE LOW WILL SLOWLY MAKE THEIR WAY INTO NORTHERN MN ALLOWING THE WARM SECTOR TO DESTABILIZE THROUGHOUT THE DAY ON THURSDAY. DEPENDING ON THE RESIDUAL CLOUD COVER...AFTERNOON HIGH TEMPS COULD EASILY CLIMB INTO THE 90S ACROSS SOUTHEASTERN MN AND WESTERN WI. FOR NOW DID NOT GO MUCH ABOVE GUIDANCE SINCE SHOWERS AND THUNDERSTORMS COULD DEVELOP ALONG THE TRAILING COLD FRONT LIMITING THE DIABATIC HEATING. A FEW OF THESE STORMS ARE LIKELY TO BE SEVERE AS FORECAST SOUNDINGS SHOW NEARLY 4000J/KG OF CAPE BY LATE AFTERNOON AND AROUND 30KTS OF DEEP LAYER SHEAR ALONG AND EAST OF THE MN/WI BORDER. THIS AFOREMENTIONED COLD FRONT IS THE LAST REAL AREA OF INTEREST. AGAIN FORECAST SOUNDINGS SHOW STRONG COLD AIR ADVECTION IN THE WAKE OF THE FRONT. THIS WILL KEEP THE BOUNDARY LAYER WELL MIXED WITH NORTHWESTERLY WIND GUSTS OF 20 TO 30MPH EXPECTED TO PREVAIL AFTER DARK. THEREFORE INCREASED THE WINDS THURSDAY NIGHT...AND USED LESS BIAS-CORRECTED GRIDS FOR OVERNIGHT LOWS SINCE THE TEMPERATURES SHOULD BE RATHER UNIFORM. ALSO RAISED CLOUD COVER SINCE SOUNDINGS SHOW SATURATION ABOVE THE BOUNDARY LAYER. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 325 AM CDT THU SEP 4 2014 THE FIRST HALF OF THE LONG TERM LOOKS RATHER QUIET. THERE WILL BE A SPLIT FLOW PATTERN DEVELOPING WITH THE SUBTROPICAL JET TO THE SOUTH KEEPING THE HEAT CONFINED TO THE SOUTHERN STATES...AND THE POLAR JET ACROSS CENTRAL CANADA KEEPING THE UNSEASONABLY COOL AIR TO THE NORTH - AT LEAST FOR THE TIME BEING. SURFACE HIGH PRESSURE WILL GUARANTEE MOSTLY CLEAR SKIES THROUGH SUNDAY NIGHT. THINGS BECOME A BIT MORE COMPLEX NEXT WEEK AS THE POLAR JET BEGINS TO SINK SOUTH. A MORE ACTIVE PATTERN IS IN THE OFFING WITH SEVERAL DISTURBANCES SKIRTING ALONG THE NORTHERN TIER OF THE U.S. HOWEVER...WITH THE SUBTROPICAL JET REMAINING SOUTH IT DOES NOT APPEAR ANY OF THESE DISTURBANCES WILL HAVE A WHOLE LOT OF MOISTURE TO WORK WITH. THEREFORE KEPT POPS IN THE CHC RANGE. EVENTUALLY THE JETS WILL PHASE AND CARVE OUT A DEEP TROUGH OVER CANADA AND THE NORTHERN U.S. SOME TIME DURING THE MIDDLE OF NEXT WEEK. THE MUCH COOLER TEMPS ACCOMPANYING THIS TROUGH SHOULD MARK THE FIRST CRACK AT AUTUMN WEATHER. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 552 AM CDT THU SEP 4 2014 VERY CHALLENING FORECAST WITH CIGS TODAY...FOLLOWED BY PRECIP CHANCES THIS AFTERNOON...AND THE WINDS BEHIND THE FRONTAL PASSAGE TONIGHT. LONG STORY SHORT...THE STRONGEST STORMS WILL STAY NORTH OF THE TAF SITES THIS MORNING. MVFR/IFR CLOUDS COULD DEVELOP SOUTH OF THIS COMPLEX...AND AFFECT ALL SITED EXCEPT KRWF. A FEW SCATTERED SHWOERS AND THUNDERSTORMS ARE EXPECTED LATE THIS AFTERNOON ALONG THE MN/WI BORDER AND POINTS EAST. TONIGHT FORECAST SOUDNINGS SHOW A SECOND SURGE OF COLD AIR BEHIND THE FRONT SO EXPECT WIND GUSTS TO PICK UP FROM THE NORTHWEST AFTER 06Z. KMSP... MVFR CIGS THIS MORNING SHOULD GIVE WAY TO VFR CONDITIONS. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE LATER THIS AFTERNOON...BUT COVERAGE WILL BE LIGHT SO NOT INCLUDING ANYTHING BEYOND VCSH. WINDS WILL GRADUALLY BECOME SW TO NW TODAY...WITH STORNGER GUSTS PICKING UP LATE TONIGHT THROUGH EARLY FRIDAY MORNING. /OUTLOOK FOR KMSP/ FRI...VFR. WINDS NW 10G20 KTS. SAT...VFR. WINDS W 5-10 KTS. SUN...VFR. WINDS SW 5-10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...JRB LONG TERM...BORGHOFF AVIATION...JRB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
325 AM CDT THU SEP 4 2014 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 325 AM CDT THU SEP 4 2014 MAIN CONCERNS WITH THIS PERIOD ARE THE FORWARD PROPAGATING MCS THAT IS EXPECTED TO DEVELOP AND RACE ACROSS CENTRAL MN EARLY THIS MORNING. THIS WILL BE FOLLOWED BY HOT AND HUMID TEMPERATURES ACROSS EASTERN MN AND WESTERN WI...WITH A FEW SHOWERS AND THUNDERSTORMS POSSIBLE BY LATE AFTERNOON. MEANWHILE A SEASONABLY STRONG COLD FRONT WILL PUSH THROUGH THE REGION AND BRING BREEZY NORTHWESTERLY WINDS OVERNIGHT ALONG WITH COOL/DRY AIR. THE FIRST ORDER OF DISCUSSION IS THE SEVERE WEATHER THREAT THIS MORNING RELATED TO THE CONVECTION ACROSS NORTH DAKOTA. HIRES MODELS SUCH AS THE HRRR AND 00/03Z RUNS OF THE HOPWRF ARE IN REMARKABLE AGREEMENT THAT THIS CONVECTION WILL INTENSIFY AS IT MOVES INTO WESTERN MINNESOTA AND DEVELOP INTO A BOW ECHO. THIS STORM MODE SEEM VERY PLAUSIBLE CONSIDERING THE ORIENTATION OF THE DEEP LAYER SHEAR VECTORS IN RELATION TO THE WARM FRONT AND MUCAPE GRADIENT...SO INCLUDED DAMAGING WINDS IN THE FORECAST ACROSS THE FAR NORTHERN TIER OF COUNTIES. THE HRRR SEEMS TO HAVE A BETTER HANDLE ON THE ONGOING CONVECTION...AND IT KEEPS THE MAJORITY OF THE FORECAST PRECIP NORTH OF THE CWA. HOWEVER BASED ON THE ACTUAL LOCATION OF THE WARM FRONT STILL THINK THERE IS LEGITIMATE RISK ALONG AND NORTH OF A LINE FROM ALEXANDRIA MN TO RICE LAKE WI. AS THE COLD POOL BECOMES WELL ESTABLISHED THIS CONVECTION WILL RACE EASTWARD. MEANWHILE THE UPPER LEVEL WAVE AND SURFACE LOW WILL SLOWLY MAKE THEIR WAY INTO NORTHERN MN ALLOWING THE WARM SECTOR TO DESTABILIZE THROUGHOUT THE DAY ON THURSDAY. DEPENDING ON THE RESIDUAL CLOUD COVER...AFTERNOON HIGH TEMPS COULD EASILY CLIMB INTO THE 90S ACROSS SOUTHEASTERN MN AND WESTERN WI. FOR NOW DID NOT GO MUCH ABOVE GUIDANCE SINCE SHOWERS AND THUNDERSTORMS COULD DEVELOP ALONG THE TRAILING COLD FRONT LIMITING THE DIABATIC HEATING. A FEW OF THESE STORMS ARE LIKELY TO BE SEVERE AS FORECAST SOUNDINGS SHOW NEARLY 4000J/KG OF CAPE BY LATE AFTERNOON AND AROUND 30KTS OF DEEP LAYER SHEAR ALONG AND EAST OF THE MN/WI BORDER. THIS AFOREMENTIONED COLD FRONT IS THE LAST REAL AREA OF INTEREST. AGAIN FORECAST SOUNDINGS SHOW STRONG COLD AIR ADVECTION IN THE WAKE OF THE FRONT. THIS WILL KEEP THE BOUNDARY LAYER WELL MIXED WITH NORTHWESTERLY WIND GUSTS OF 20 TO 30MPH EXPECTED TO PREVAIL AFTER DARK. THEREFORE INCREASED THE WINDS THURSDAY NIGHT...AND USED LESS BIAS-CORRECTED GRIDS FOR OVERNIGHT LOWS SINCE THE TEMPERATURES SHOULD BE RATHER UNIFORM. ALSO RAISED CLOUD COVER SINCE SOUNDINGS SHOW SATURATION ABOVE THE BOUNDARY LAYER. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 325 AM CDT THU SEP 4 2014 THE FIRST HALF OF THE LONG TERM LOOKS RATHER QUIET. THERE WILL BE A SPLIT FLOW PATTERN DEVELOPING WITH THE SUBTROPICAL JET TO THE SOUTH KEEPING THE HEAT CONFINED TO THE SOUTHERN STATES...AND THE POLAR JET ACROSS CENTRAL CANADA KEEPING THE UNSEASONABLY COOL AIR TO THE NORTH - AT LEAST FOR THE TIME BEING. SURFACE HIGH PRESSURE WILL GUARANTEE MOSTLY CLEAR SKIES THROUGH SUNDAY NIGHT. THINGS BECOME A BIT MORE COMPLEX NEXT WEEK AS THE POLAR JET BEGINS TO SINK SOUTH. A MORE ACTIVE PATTERN IS IN THE OFFING WITH SEVERAL DISTURBANCES SKIRTING ALONG THE NORTHERN TIER OF THE U.S. HOWEVER...WITH THE SUBTROPICAL JET REMAINING SOUTH IT DOES NOT APPEAR ANY OF THESE DISTURBANCES WILL HAVE A WHOLE LOT OF MOISTURE TO WORK WITH. THEREFORE KEPT POPS IN THE CHC RANGE. EVENTUALLY THE JETS WILL PHASE AND CARVE OUT A DEEP TROUGH OVER CANADA AND THE NORTHERN U.S. SOME TIME DURING THE MIDDLE OF NEXT WEEK. THE MUCH COOLER TEMPS ACCOMPANYING THIS TROUGH SHOULD MARK THE FIRST CRACK AT AUTUMN WEATHER. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1057 PM CDT WED SEP 3 2014 CONVECTION WILL AFFECT KEAU AT THE START OF THE TAF PERIOD...AND THEN A LULL IN THE ACTIVITY IS EXPECTED WITH LOWERING CIGS BECOMING THE PRIMARY CONCERN UNTIL THE NEXT BATCH OF SHOWERS AND THUNDERSTORMS APPROACHES FROM THE WEST. NAM AND GFS GUIDANCE PROG EXTENSIVE IFR CIGS TO DEVELOP OVERNIGHT...HOWEVER...TRENDS HAVE NOT BEEN SUPPORTING THAT THEORY THUS FAR. SO...WILL LEAN TOWARD THE 04.02Z RAP13 0.5 KM AGL CONDENSATION PRESSURE DEFICIT PROG...WHICH BOTTLES THE MVFR/IFR CIGS OVER CENTRAL MN JUST NORTH OF THE WARM FRONT. THIS MEANS THE MOST NOTABLE CIG REDUCTIONS WOULD BE EXPERIENCED AT KAXN AND KSTC...POSSIBLY ARCING DOWN TOWARD KRNH AND KEAU. KMSP WOULD BE ON THE EDGE...SO HAVE GONE A BIT MORE OPTIMISTIC WITH CIGS THERE...BUT STILL FEATURE A PERIOD OF MVFR/IFR OVERNIGHT. IN ADDITION TO CIGS...ANOTHER CONCERN IS THE POTENTIAL FOR CONVECTION TO DEVELOP OVERNIGHT OVER THE DAKOTAS AND SPREAD EASTWARD INTO THE AREA DURING THE EARLY MORNING HOURS ON THURSDAY. RIGHT NOW THINK KAXN AND KSTC ARE THE MOST SUSCEPTIBLE TO EXPERIENCING SAID ACTIVITY...BUT CONFIDENCE ON DEVELOPMENT IS ADMITTEDLY LOW. THINK ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS WILL DEVELOP AS THE COLD FRONT MOVES ACROSS THE AREA. HAVE INCLUDED PROB30S AS CONFIDENCE IN TIMING/COVERAGE IS LOW. EAST/SOUTHEAST WINDS SHIFT TO NORTHWEST ON THURSDAY IN THE WAKE OF THE FRONT...AND BECOME GUSTY. KMSP... HAVE GONE A BIT MORE OPTIMISTIC WITH CIGS OVERNIGHT...BUT STILL THINK CIGS WILL DIP BELOW 1700 FT OVERNIGHT...WITH MVFR BR POSSIBLE AS WELL. COULD SEE A FEW SHOWERS APPROACHING THE FIELD AFTER DAYBREAK /WITH DAKOTAS ACTIVITY WANING AS IT APPROACHES/...BUT A SLIGHTLY HIGHER PROBABILITY WILL BE WITH THE COLD FRONT AFTER 21Z. /OUTLOOK FOR KMSP/ FRI...VFR. WINDS NW 10G15 KTS. SAT...VFR. WINDS W 5-10 KTS. SUN...VFR. WINDS SW 5-10 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...JRB LONG TERM...BORGHOFF AVIATION...LS
AREA FORECAST DISCUSSION
NWS HASTINGS NE
617 PM CDT FRI SEP 5 2014 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 345 PM CDT FRI SEP 5 2014 THE PRIMARY ISSUES IN THE NEXT 24 HOURS ARE FOCUSED RIGHT AWAY IN THESE FIRST FEW HOURS...CENTERED AROUND TIMING THE BACK END OF LIGHT RAIN SHOWERS THAT CONTINUE A STEADY NORTHWEST-TO-SOUTHEAST DEPARTURE ACROSS THE CWA. OTHERWISE...AFTER A SEASONABLY COOL NIGHT THAT LOOKS TO DROP THE ENTIRE CWA INTO THE MID-UPPER 40S FOR LOWS FOR THE FIRST TIME SINCE MAY OR JUNE...SATURDAY IS SHAPING UP TO BE A VERY PLEASANT/DRY DAY WITH NO WORSE THAN PARTLY CLOUDY SKIES AND VERY LIGHT BREEZES...EXCELLENT FOR OUTDOOR ACTIVITIES. STARTING OFF WITH THE HERE AND NOW AS OF 19Z/2PM...THINGS HAVE LARGELY PANNED OUT AS EXPECTED SINCE WALKING IN THE DOOR THIS MORNING. ALTHOUGH THIS WILL BE SOMEWHAT OUTDATED BY THE TIME THIS PRODUCT COMES OUT...THE BACK EDGE OF LIGHT RAIN CURRENTLY EXTENDS FROM NEAR FULLERTON-GRAND ISLAND-ALMA...WITH LOCATIONS NORTHWEST OF THIS LINE ALL BUT DONE WITH PRECIP. ALTHOUGH LIMITED PLACES PICKED UP SOME DECENT RAIN AMOUNTS AROUND 0.50 INCH OR HIGHER LAST NIGHT/EARLY THIS MORNING...THE BALANCE OF DAYTIME RAIN HAS LIKELY YIELDED NO MORE THAN 0.10 INCH. QUITE A CHANGE FROM THE HEAVY RAIN STORMS THAT TRAVERSED THE AREA OVER THE PAST FEW WEEKS. SPEAKING OF QUITE A CHANGE...TEMPS AS OF 2PM ARE ONLY HOVERING SOMEWHERE IN THE 57-64 RANGE ACROSS THE CWA. FOR ALL EXCEPT THE FAR SOUTHEASTERN CWA...AT LEAST A LITTLE BIT OF FILTERED SUNSHINE COULD BREAK OUT BEFORE DAYS END...SO STILL EXPECTING THE MAJORITY OF THE CWA TO EVENTUALLY REALIZE DAYTIME HIGHS AT LEAST INTO THE 61-64 RANGE...MARKING THE FIRST TIME SINCE JUNE 9TH THAT PLACES SUCH AS GRAND ISLAND/HASTINGS HAVE FAILED TO REACH 70. IN THE BIG PICTURE OF THE MID-UPPER LEVELS...THE TRAILING PORTION OF A LOW AMPLITUDE SHORTWAVE TROUGH IS CURRENTLY TRAVERSING THE CWA...AS SEASONABLY STRONG QUASI-ZONAL FLOW DOMINATES THE CENTRAL CONUS IN BETWEEN A FLAT SOUTHERN CONUS RIDGE AND A LARGE SCALE TROUGH ACROSS CENTRAL/EASTERN CANADA. AT THE SURFACE...THE LARGE-SCALE COLD FRONT HAS SURGED WELL SOUTH OF THE LOCAL AREA...ALONG AN AXIS FROM THE GREAT LAKES-CENTRAL MO-NORTHERN OK-TX PANHANDLE. IN ITS WAKE...A ROUGHLY 1024 MILLIBAR HIGH HAS BUILT SOUTHWARD INTO THE CENTRAL PLAINS...PROVIDING FOR 5-15 MPH NORTHERLY BREEZES THIS AFTERNOON ACROSS THE CWA. VISIBLE SATELLITE CURRENTLY DEPICTS AT LEAST LIMITED FILTERED SUN NOSING INTO NORTHWESTERN PORTIONS OF THE CWA...WHILE CONSIDERABLE CLOUD COVER PERSISTS IN MOST PLACES. LOOKING FORWARD IN THE FORECAST AND STARTING WITH THESE FIRST 3-6 HOURS...WILL BE MAKING SOME LAST MINUTE ADJUSTMENTS TO POP TRENDS BASED ON THE LATEST RADAR DATA BEFORE SENDING THE "FINAL" FORECAST...BUT WITH THE BACK EDGE OF PRECIPITATION TIED FAIRLY CLOSELY TO THE TROUGH AXIS AT 700MB AND RESULTANT ISENTROPIC DOWNGLIDE AS EVIDENT ON THE 310K SURFACE...A CONTINUED STEADY DEPARTURE IS EXPECTED. PRIOR TO 00Z/7PM...THE MOST LIKELY ZONE FOR STEADY LIGHT MEASURABLE RAIN WILL FOCUS SOUTHEAST OF A YORK- PHILLIPSBURG LINE...AND ESPECIALLY SOUTH OF A MANKATO-STOCKTON LINE. AFTER 00Z/7PM...THE MAJORITY OF SHORT TERM MODEL DATA INCLUDING THE LATEST HRRR/RAP13 INDICATE THAT ONLY THE FAR SOUTHEASTERN FRINGES OF THE CWA (MAINLY MITCHELL COUNTY KS AND VICINITY) SHOULD HAVE ANY LINGERING LIGHT RAIN...WITH EVEN THIS QUICKLY DEPARTING TO THE SOUTH-SOUTHEAST BY 02-3Z/9-10PM AT THE LATEST. IN SUMMARY...THE ENTIRE CWA SHOULD BE RAIN-FREE BY NIGHTFALL OR SHORTLY THEREAFTER...AND MOST PLACES WELL BEFORE THEN. FOR THE MAIN EVENING/OVERNIGHT HOURS...THE BIG PICTURE ALOFT FEATURES THE DEPARTURE OF THE CURRENT SHORTWAVE TROUGH...WHILE SOME TRAILING WEAK ENERGY SETTLES SOUTHWARD TOWARD NEB...TRAILING SOUTHWESTWARD FROM A STRONGER WAVE TRACKING SOUTHEAST THROUGH MANITOBA/ONTARIO. ALTHOUGH CERTAINLY NOT EXPECTING ANY OVERNIGHT PRECIP...ITS LIKELY NOT GOING TO BE CRYSTAL CLEAR SKIES EITHER IN MANY AREAS...AS AT LEAST A PARTIAL COVERAGE OF MID-HIGH CLOUDS DRIFTS OVERHEAD AT VARIOUS POINTS TONIGHT...ESPECIALLY POST- MIDNIGHT. OVERALL THOUGH...A MOSTLY CLEAR TO PARTLY CLOUDY NIGHT. ALTHOUGH ANY CLOUDS MAY PRECLUDE TRULY IDEAL RADIATIONAL COOLING CONDITIONS...THE PRESENCE OF THE 1025 MILLIBAR SURFACE RIDGE AXIS PARKED OVER THE AREA WILL PROMOTE VERY LIGHT/GENERALLY VARIABLE BREEZES. ALL THINGS CONSIDERED...STUCK PRETTY CLOSE TO A MET/MAV GUIDANCE BLEND FOR OVERNIGHT LOWS...AIMING MOST OF THE CWA IN THE 46-49 RANGE...WITH COLDER READINGS IN THE 43-45 RANGE MOST FAVORED IN THE TYPICAL VALLEY/DAWSON COUNTIES AREA. FOR MUCH OF THE CWA...THESE LOWS WERE NUDGED UP 2-3 DEGREES FROM PREVIOUS FORECAST. ON ONE LAST NOTE...ALTHOUGH THE LIGHT BREEZES AND MOIST GROUND COULD FOSTER AT LEAST SOME PATCHY LIGHT FOG DEVELOPMENT LATE TONIGHT...AM NOT SEEING ENOUGH OF A FOG SIGNAL IN THE LATEST MODELS/GUIDANCE TO FORMALLY INTRODUCE TO THE FORECAST...BUT THIS POSSIBILITY CANNOT BE COMPLETELY IGNORED BY THE NEXT FEW SHIFTS. FOR SATURDAY DAYTIME...VERY PLEASANT OVERALL. THE LARGE SCALE MID/UPPER PATTERN CHANGES LITTLE WITH FAIRLY UNEVENTFUL ZONAL TO SLIGHTLY NORTHWESTERLY FLOW IN PLACE OVERHEAD BETWEEN THE FLAT SOUTHERN CONUS RIDGE AND SOUTHEAST CANADA MEAN TROUGH. ALTHOUGH THE DAY AS A WHOLE SHOULD AVERAGE NO WORSE THAN PARTLY CLOUDY...VERY WEAK DISTURBANCES IN THE FLOW APPEAR PRIMED TO PROMOTE AT LEAST A FEW ENHANCED PATCHES OF MID LEVEL CLOUD COVER...ESPECIALLY DURING THE MORNING. AT THE SURFACE...THE AFOREMENTIONED RIDGE AXIS WILL VERY SLOWLY SLIDE EAST ACROSS THE CWA...BECOMING CENTERED OVER EASTERN NEB BY LATE AFTERNOON. AS A RESULT...BREEZES ACROSS THE LOCAL AREA WILL BE VERY LIGHT...AVERAGING AROUND 5 MPH OR LESS FOR MOST OF THE DAY IN MOST AREAS. ALTHOUGH WIND DIRECTION WILL LIKELY BE VARIABLE FOR PART OF THE DAY...A GENERALLY NORTHERLY COMPONENT IN THE MORNING SHOULD BECOME MORE SOUTHEASTERLY LATER IN THE DAY. DESPITE THE LIMITED MIXING WITHIN THE RIDGE AXIS...AS LONG AS CLOUDS ARE NOT MORE ABUNDANT THAN CURRENTLY EXPECTED HIGHS ARE FORECAST TO CLIMB INTO THE 71-74 RANGE CWA-WIDE (WHICH IS STILL ABOUT 10 DEGREES BELOW NORMAL/AVERAGE FOR THE DATE). .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 345 PM CDT FRI SEP 5 2014 AN AREA OF SURFACE HIGH PRESSURE ACROSS EASTERN NEBRASKA WILL SHIFT INTO PORTIONS OF IOWA AND MISSOURI LATE SATURDAY THROUGH SUNDAY...RESULTING IN A RETURN TO SOUTHERLY FLOW ACROSS THE REGION. THAT SAID...WITH RELATIVELY CLOUD FREE SKIES AND A COOL AIRMASS IN PLACE TO START THE EXTENDED PERIODS...EXPECT A COOL START TO THE DAY ON SUNDAY...WITH MORNING LOWS GENERALLY FORECAST TO BE 5-10 DEGREES BELOW SEASONAL NORMS. THIS COOL START TO THE DAY WILL BE REPLACED BY A NICE AFTERNOON...HOWEVER...AS 850 MB TEMPS STARTING TO REBOUND AND HIGH TEMPERATURES CLIMB INTO THE MID TO UPPER 70S ACROSS THE MAJORITY OF THE FORECAST AREA. WHILE MOST OF THE AREA IS EXPECTED TO REMAIN DRY ON SUNDAY...COULD SEE SOME SHOWERS AND THUNDERSTORMS DEVELOP ACROSS NORTHEASTERN PORTIONS OF THE FORECAST AREA SUNDAY NIGHT INTO EARLY MONDAY MORNING AS AN INCREASING LOW LEVEL JET WILL BE POINTED ACROSS NORTHEASTERN NEBRASKA. WHILE THE FLOW ALOFT WILL BE PRIMARILY ZONAL TO START THE EXTENDED PERIODS...THE FIRST NOTABLE UPPER LEVEL DISTURBANCE IS NOT EXPECTED TO TRAVERSE THE PLAINS UNTIL MONDAY NIGHT. THAT SAID...WITH PLENTY OF INSTABILITY AND MODEST SHEAR IN PLACE...COULD ACTUALLY SEE SOME STRONG TO LOCALLY SEVERE STORMS DEVELOP ACROSS THE LOCAL AREA IN THIS ENVIRONMENT...WITH LARGE HAIL AND STRONG THUNDERSTORM WIND GUSTS BEING THE PRIMARY CONCERNS. WITH MODELS DIFFERING IN THE TIMING OF DISTURBANCES CROSSING THE LOCAL AREA...KEPT CHANCES FOR THUNDERSTORMS IN THE FORECAST NEAR CONTINUOUSLY MONDAY NIGHT THROUGH WEDNESDAY AFTERNOON...ALTHOUGH EVENTUALLY THERE ARE EXPECTED TO BE DISTINCT BREAKS IN THE ACTIVITY BETWEEN THE PASSING UPPER LEVEL WAVES. A PASSING COLD FRONT WILL THEN BRING A TRANSITION TO MORE SHOWERY ACTIVITY BY WEDNESDAY EVENING. WHILE TEMPERATURES WILL FALL BEHIND THE INITIAL COLD FRONT WEDNESDAY...THE COOLER AIR IS NOT EXPECTED TO INFILTRATE THE REGION UNTIL THURSDAY...WHEN 850 MB TEMPS FALL IN THE SINGLE DIGITS TO NEAR ZERO...AS DEPICTED BY BOTH THE EC/GFS. THIS WOULD BE NOTABLY COOLER THAN THE AIRMASS BEHIND TODAYS COLD FRONT...AND EXPECT A COOL END TO NEXT WEEK AS A RESULT. GIVEN INHERENT UNCERTAINTY IN MODEL DATA SO FAR OUT...STUCK VERY CLOSE TO CONSENSUS FORECAST...BUT COULD VERY WELL SEE TEMPERATURES TREND DOWNWARD THE NEXT SEVERAL DAYS IF CURRENT OUTLOOK HOLDS. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 611 PM CDT FRI SEP 5 2014 CLOUDS ARE BREAKING UP THIS EVENING IN A DRIER AIRMASS AS SURFACE HIGH PRESSURE SETTLES ONTO THE CENTRAL PLAINS. THE HRRR SUGGESTS PATCHY VSBY RESTRICTIONS POTENTIALLY DEVELOPING IN THE KEAR AREA AROUND 10Z BUT IT IS SPOTTY AT BEST AND WILL MONITOR. MVFR CLOUDS ARE EXPECTED TO REMAIN SCATTERED WITH VFR CLOUDS PROJECTED TO MOVE SATURDAY MORNING. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...PFANNKUCH LONG TERM...ROSSI AVIATION...FAY
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
311 PM CDT THU SEP 4 2014 .SHORT TERM...(TONIGHT THROUGH SUNDAY) ISSUED AT 310 PM CDT THU SEP 4 2014 CHANCE FOR SHOWERS AND STORMS TONIGHT...AND COOLER TEMPERATURES TO FOLLOW...ARE THE PRIMARY SHORT RANGE FORECAST CONCERNS. COLD FRONT WAS SLIPPING SOUTHEAST THROUGH THE CWA THIS AFTERNOON. LATEST RAP ANALYSIS SHOWS INSTABILITY INCREASING AHEAD OF THE FRONT WHERE MLCAPES WERE OVER 3000 J/KG ACROSS SOUTHEAST NEBRASKA AND SOUTHWEST IOWA. HOWEVER WARM MID LEVEL TEMPERATURES WERE PROVIDING A CAP FOR STORMS AHEAD OF THE FRONT. BEHIND THE FRONT SCATTERED SHOWERS AND STORMS HAD DEVELOPED IN SOUTHEAST SOUTH DAKOTA TIED TO WAVE RIDING THROUGH THE NORTHERN PLAINS...BUT THOSE HAD MOVED OFF TO THE NORTHEAST OR HAD DISSIPATED BY MID AFTERNOON. GIVEN CAPPING ALONG AND AHEAD OF FRONT...SEEMS UNLIKELY WE WILL SEE DEVELOPMENT THERE THIS AFTERNOON OR EVENING. BEHIND THE FRONT...MORE DEVELOPMENT WILL HAVE TO WAIT UNTIL SHORTWAVE CURRENTLY MOVING INTO EASTERN COLORADO MOVES INTO OUR AREA. LATEST SHORT RANGE MESOSCALE MODELS SUGGEST THIS WILL NOT HAPPEN UNTIL LATE THIS EVENING...AND FOCUS ON AREAS NEAR AND NORTHWEST OF INTERSTATE 80...WITH A GRADUAL DRIFT AND EXPANSION TO THE SOUTHEAST DURING THE OVERNIGHT. STRONGER MID LEVEL SHORTWAVE PROVIDING MID LEVEL FRONTOGENESIS IS FORECAST TO OVERSPREAD THE REGION FRIDAY AFTERNOON AND EVENING BEFORE MOVING OFF TO THE EAST FRIDAY NIGHT. WILL CONTINUE CHANCE FOR SHOWERS MUCH OF FRIDAY WITH DECREASING CHANCES FRIDAY NIGHT. SURFACE HIGH PRESSURE WITH NORTHWEST FLOW ALOFT WILL THEN TAKE OVER AND BRING MILD AND DRY WEATHER FOR THE BULK OF THE WEEKEND. RETURN FLOW SETTING UP ON SUNDAY COULD SPREAD MORE CLOUDS INTO THE REGION...BUT WILL KEEP PRECIPITATION OUT OF THE FORECAST THROUGH THE AFTERNOON. COOLER WEATHER IS ALSO ON TAP FOR THE WEEKEND. TEMPERATURES AHEAD OF COLD FRONT WERE IN THE 90S THIS AFTERNOON...WITH 70S OR EVEN 60S NOTED IN SOUTH DAKOTA IN DEEPER COLD AIR BEHIND THE FRONT CORRESPONDING TO 10C 850 TEMPERATURES. THAT AIR WILL SETTLE OVER OUR AREA FRIDAY AND SATURDAY BEFORE WARMING TO NEAR 14C ON SUNDAY. MODEL OUTPUT AGREES WITH OUR GOING FORECAST FOR UPPER 60S TO LOWER 70S FRIDAY AND SATURDAY...WITH MID 70S OR SO ON SUNDAY. SEE NO REASON TO MOVE FROM THOSE NUMBERS TOO MUCH. .LONG TERM...(SUNDAY NIGHT THROUGH THURSDAY) ISSUED AT 310 PM CDT THU SEP 4 2014 UPPER LEVEL FLOW PATTERN WILL BECOME MORE ZONAL FOR THE FIRST HALF OF THE WEEK BEFORE LARGE UPPER TROUGH SETTLES INTO THE CONUS FOR THE LATTER HALF. STRONG SHORTWAVE MOVING THROUGH THE PLAINS WILL BRING RAIN CHANCES TO OUR AREA SUNDAY NIGHT THROUGH MONDAY BEFORE EJECTING EAST MONDAY NIGHT. RETURN FLOW BEGINNING SUNDAY WILL PROVIDE PLENTY OF MOISTURE FOR STORMS MONDAY AFTERNOON WHEN SURFACE-BASED CAPES SHOULD TOP 2000 J/KG AND BULK 0-6KM SHEAR OVER 40KT. SEVERE STORMS ARE POSSIBLE MONDAY AFTERNOON IF STORMS DO FIRE. WITH WAVE EXITING TUESDAY...WE SHOULD SEE A DRY PERIOD UNTIL HEIGHTS BEGIN TO LOWER WEDNESDAY WITH APPROACH OF DEEPER UPPER TROUGH SETTLING INTO THE PLAINS. CORE OF UPPER TROUGH/LOW WILL MOVE INTO THE NORTHERN PLAINS BY THURSDAY...AND WILL DRIVE A COLD FRONT THROUGH OUR AREA WEDNESDAY. ANOTHER CHANCE FOR THUNDERSTORMS WILL ACCOMPANY THAT FRONT...THEN MAINLY SHOWERS IN OVERRUNNING REGIME BEHIND THE FRONT FOR WEDNESDAY NIGHT INTO THURSDAY. TEMPERATURES WILL BE SLOWLY WARMING AHEAD OF WEDNESDAY COLD FRONT...WITH HIGHS BETWEEN 75 AND 85...THEN MUCH COOLER THURSDAY WITH HIGHS IN THE 60S. && .AVIATION...(18Z TAFS FOR KOFK...KLNK AND KOMA.) ISSUED AT 1246 PM CDT THU SEP 4 2014 A COLD FRONT WILL CONTINUE TO DROP SOUTH OVER THE TAF SITES THIS AFTERNOON TURNING SFC WINDS TO THE NORTHWEST. THE FRONT IS ALREADY THROUGH KOFK...AND WILL BE THROUGH KOMA AND KLNK IN THE NEXT FEW HOURS. AN MVFR DECK EXTENDS BEHIND THE FRONT AND WILL CONTINUE INTO THE EVENING HOURS. CONVECTION IS LIMITED THIS AFTERNOON DUE TO A STRONG CAP IN PLACE...BUT SHOWERS AND THUNDERSTORMS WILL BECOME LIKELY AFTER DARK. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ SHORT TERM...DERGAN LONG TERM...DERGAN AVIATION...KERN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
953 PM EDT FRI SEP 5 2014 .SYNOPSIS... A COLD FRONT WILL APPROACH THE EASTERN GREAT LAKES TONIGHT BRINGING A FEW SHOWERS OR THUNDERSTORMS TO UPSTATE NEW YORK MAINLY. THIS COLD FRONT WILL CROSS THE REGION SATURDAY WITH MORE WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY. ONCE THIS FRONT PASSES BY SATURDAY NIGHT...HIGH PRESSURE WITH COOLER AND LESS HUMID WEATHER WILL RETURN FOR SUNDAY AND MONDAY. && .NEAR TERM /THROUGH SATURDAY/... 950 PM UPDATE... A LINE OF INTENSE CONVECTION EXTENDS FROM LOWER ONTARIO BACK THROUGH ILLINOIS AT THIS HOUR. THE NORTHERN EDGE OF THE CONVECTION IS SHOWING SIGNS OF WEAKENING, WHILE THE MORE INTENSE PORTION OF THE LINE IS DIVING INTO THE UNSTABLE AIR OVER THE OHIO VALLEY (MLCAPES 2000-2500 J/KG). THIS OBSERVED TREND IS IN AGREEMENT WITH THE LATEST HRRR RUN, WHICH BRINGS A FEW THUNDERSTORMS INTO SOUTHWESTERN NY AROUND 6Z AND WEAKENS THEM CONSIDERABLY. MAKING A FEW TIMING ADJUSTMENTS TO THE POPS GRIDS FOR THE OVERNIGHT HOURS...OTHERWISE THE GRIDS APPEAR TO BE IN GOOD SHAPE. 4 PM DISC... RADARS SHOW SCATTERED SHOWERS AND SOME THUNDERSTORMS FIRING OVER THE CENTRAL MTNS OF PENNSYLVANIA WITH THE DIURNAL HEATING AND LOCALIZED MTN AND VALLEY CIRCULATIONS AS UPPER FORCING IS RATHER WEAK. SPC MESOANALYSIS SHOWS CAPES OF 1000 J/KG TO 1500 J/KG ACROSS MOST OF THE FINGER LAKES AND IN NORTHEAST PA WITH CAPES LESS THAN 1000 J/KG FARTHER NORTH TO THE UPPER MOHAWK VALLEY. WATER VAPOR IMAGERY CONTINUES TO SHOW AN ELONGATED PV MAXIMUM ON THE SOUTHERN EDGE OF THE WESTERLIES ACROSS THE OHIO VALLEY TO LOWER MISSISSIPPI VALLEY HEADING NORTHEAST INTO NE PA AND CENTRAL AND EASTERN NY STATE. ALL SYNOPTIC AND MESOSCALE MODELS BRING THIS SHEARING OUT WEAKENING FEATURE THRU C NY AND NE PA BY LATE AFTERNOON OR EARLY EVENING. AS THIS FEATURE PASSES BY I STILL CUD SEE AN ISLD SHOWER OR THUNDERSTORM OVER THE HIGHER TERRAIN OF THE POCONOS WHERE LOCALIZED UPSLOPE AND MTN-VLLY CIRCULATIONS CUD TRIGGER SOMETHING. REST OF AREA I DON/T SEE ANYTHING FORMING OF SIGNIFANCE THIS EVENING. SO I WILL MAINTAIN SLGHT CHC POPS FOR SHRA/TSRA UNTIL JUST AFTER 00Z WITH LOSS OF DAY/S HEATING IN THE POCONOS. NEXT FEATURE TO WATCH IN THE NEAR TERM WAS THE REMNANTS OF AN MCS TRACKING E-NE ACROSS LAKE HURON INTO SRN ONT. THE MEAN WINDS IN THE 850 MB TO 300 MB STEERING LAYER WERE FROM 250 DEGREES WITH THE INFLOW FOR THE STORMS FROM THE SOUTHWEST. THIS WILL KEEP THESE SHRA AND STORMS MOVING TO THE E AND MAINLY N OF C NY AND NE PA LATE AFTERNOON OR EARLY EVENING. BUT LATER TONIGHT...A STRONG UPPER LEVEL WAVE OVER JAMES BAY CANADA WITH ASSCTD STRONG SURFACE LOW WHICH TRIGGERED THIS MCS WILL PASS FARTHER EAST. THIS WILL PUSH A COLD FRONT SOUTHWARD. HENCE THE REMNANTS OF THIS MCS WILL BECOME REFOCUSED ALONG THIS COLD FRONT AND HEAD DOWN INTO NY STATE OVERNIGHT. THIS WILL OCCUR WHEN THE INSTABILITY IS AT ITS DIURNAL MINIMUM SO I EXPECT ACVTY WILL WANE AS IT DROPS S TO THE PA BRDR LATE TONIGHT AND EVENTUALLY FIZZLE. HAVE HIGHER POPS FOR SHRA/TSRA IN NC NY OVERNIGHT AND LOWER POPS FARTHER S WITH SLGHT CHC INTO NRN PA LATE TONIGHT. FOR SATURDAY...LOBE OF UPPER LEVEL PV FROM THE NRN PLAINS TO THE ROCKIES WILL RAPIDLY WORK EAST TONIGHT AND REACH THE GREAT LAKES REGION TO CENTRAL PLAINS BY 12Z SATURDAY AND THEN INTO THE ERN LAKES BY 00Z SUNDAY. THIS IS A POTENT FEATURE AND WILL LEAD TO SIGNIFICANT HEIGHT FALLS...LIFTG AND COOLING ALOFT AND BE THE IMPETUS FOR PUSHING A STRG COLD FRONT THRU NY AND PA SAT. AHEAD OF THE COLD FRONT RICH BOUNDARY LAYER MOISTURE EXISTED WITH DEWPOINTS APPRCHING OR ABV 70F. CAPES EASILY CUD APPROACH 1500 J/KG AHEAD OF FRONT BETWEEN 18Z AND 00Z. WITH THE UPPER LEVEL RDG HOLDING OFFSHORE...THE HEIGHT GRADIENT INCREASES ALSO AS THIS UPPER FEATURE PRESSES EASTWARD WHICH INCREASES THE MID TO HIGH LEVEL WINDS AND EVEN THE LL WINDS. HENCE WIND SHEARS WILL BE FAIRLY IMPRESSIVE. THE 0-1 KM SHEAR WAS PROJECTED TO BE 15 TO 20 KNOTS...THE 0-6 KM SHEAR PRIOR TO CONVECTION FIRING WAS PROGGED TO BE CLOSE TO 40 KNOTS OR SLIGHTLY MORE. HENCE BELIEVE POTENTIAL EXISTS FOR SEVERE STORMS IN OUR FORECAST AREA MAINLY SAT PM. FRONTAL POSITIONING WILL BE THE KEY TO WHERE THE RISK AREA IS FOR SEVERE STORMS IN OUR FORECAST AREA. THE GFS...NAM...EURO SEEM TO AGREE THAT BY 18Z THE INSTABILITY GRADIENT WILL RUN FROM ABT COOPERSTOWN TO UCA SW TO BRADFORD CO INCLUDING BGM AND ELM IN OUR FORECAST AREA. SO LOCATIONS S AND E OF HERE WILL HAVE THE HIGHEST RISK FOR SEVERE. THE CMC IS FARTHER S AND WUD INDICATE ONLY THE POCONOS TO SULLIVAN COUNTY SEE POTENTIAL FOR INSTABILITY AND SEVERE WEATHER IN THE NWS BGM FORECAST AREA. OUR LOCAL SEVERE WEATHER CHECKLIST SUGGESTS POTENTIAL FOR BROKEN LINES AND SMALL BOW ECHOE STRUCTURES WITH WIND DAMAGE THE PRIMARY THREAT. PWATS ALSO WERE RUNNING ARND 1.8 INCHES SO HEAVY RAIN IS ALSO WORTH HIGHLIGHTING. NORTH OF THIS BNDRY...I SEE MAINLY SHRA IN THE MORNING WITH ISLD THUNDER WITH THE MAIN ACVTY REMAINING TO THE S. WILL CONTINUE TO HIGHLIGHT IN THE HWO. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... FOR SATURDAY NIGHT...FRONT PASSES E AND HIGH PRESSURE RAPIDLY SPREADS ACROSS NY AND PA WITH LIGHT WINDS AND CLEARING SKIES AS PER SYNOPTIC MODELS. WITH FAIRLY WIDESPREAD RAINFALL SATURDAY I SEE PLENTY OF VALLEY FOG FORMING BY SUN AM AND HAVE IN GRIDS. FOR SUNDAY AND SUNDAY NIGHT...HIGH PRESSURE REMAINS OVER THE REGION WITH FAIR AND PLEASANT DAYTIME WEATHER AND A CHILLY NIGHT. AGAIN I SEE PLENTY OF VALLEY FOG BY MONDAY AM WITH CLEAR SKIES LIGHT WINDS AND MINS WELL DOWN INTO THE 40S MANY AREAS. FOR MONDAY...HIGH PRESSURE WORKS E AND A SRLY RETURN FLOW BEGINS WITH SOME MODERATING BEGINNING. I DON/T EXPECT ANY PRECIP. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... 130 PM UPDATE... EXPECT SFC HIPRES TO BE BUILDING INTO THE CANADIAN MARITIMES AT THE START OF THE LONG TERM PD. A WEAK SFC LOW WL LKLY DVLP ALONG THE ERN SEABOARD TUE MRNG AS WV RIDES UP ALONG THE COAST BUT WITH 1030MB HIGH CONTROLLING AREA WX NOT EXPECTING MUCH IN THE WAY OF PCPN TO MV INTO CWA UNTIL MORE TWD TUE EVNG AND EVEN AT THAT EXPECT IT TO BE A LONG SHOT. CHC FOR SHOWERS/TSTMS CAN BE EXPECTED BEGINNING WED MRNG WITH ANOTHER TROF (DEEPER ON EC VS GFS) WORKING ITS WAY INTO THE NORTHEAST U.S. MODELS DIFFER ON POP CHANCES AFTR WED NGT WITH 12Z GFS MUCH QUICKER MVG LOPRES THRU THAN 00Z EC. MAIN REASON IS THAT 00Z EC IS MUCH MORE AMPLIFIED WITH SYSTEM AND DEEPER WITH SFC LOW. THIS IS MORE IN LINE WITH GFS ENSEMBLE MEAN AND MAJORITY OF THE ENSEMBLE MEMBERS. EXPECT TEMPS THRU THE PD TO BE NEAR. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... CONV OVER ONTARIO SHD WEAKEN AS IT HEADS EAST THE EVENING...XPCT JUST SOME VFR SHWRS ACROSS SYR AND RME LTR. OTRW VFR OR MVFR OVRNGT AS SOME LGT FOG DVLPS. STRONG COLD FNT PASSES ON SAT AND WILL TRIGGER A LINE OF CONV AFT 18Z WITH OCNL MVFR CIGS AND VSBYS. LGT WINDS OVRNGT WILL STRENGTHEN OUT OF THE SW TWRD MRNG...AND BECOME WLY ON SAT AS THE FNT APRCHS AND PASSES THRU. OUTLOOK... SAT NIGHT...MVFR RESTRICTIONS POSSIBLE BEHIND FRONT. SUN-WED...MOSTLY VFR WITH POTENTIAL FOR IFR RESTRICTIONS EACH MORNING, ESPECIALLY ELM. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN/DJP NEAR TERM...DJN SHORT TERM...DJN LONG TERM...PVN AVIATION...DGM/PVN
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1125 PM EDT FRI SEP 5 2014 .SYNOPSIS... WARM AND HUMID CONDITIONS WILL PERSIST THROUGH THE WEEKEND. SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE THIS WEEKEND THROUGH MONDAY AS A COLD FRONT DROPS SOUTHEAST AND LINGERS OVER THE AREA AS WEAK UPPER LEVEL IMPULSES PUSH ACROSS THE REGION. A GRADUAL DRYING TREND WILL GET UNDERWAY BY TUESDAY AND PERSIST THROUGH THE MID TO LATE WEEK PERIOD OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 1045 PM FRIDAY...CONVECTION FIRING OFFSHORE 40-60 MILES SSE OF CAPE FEAR...SOMEWHAT AHEAD OF SCHEDULE...AND MOVING AT A GOOD CLIP...WILL LIKELY CLIP A PORTION OF THE ILM COASTAL COUNTIES PRIOR TO DAYBREAK SAT. AS A RESULT...WILL UP POPS OVER THE ADJACENT COASTAL WATERS AND IMMEDIATE COAST TO 20-30 PERCENT. OTHERWISE...ALL ELSE REMAINS ON CUE...FOR THE MOMENT...FROM THE PREVIOUS UPDATE. PREVIOUS DISCUSSION............................................... AS OF 715 PM FRIDAY...SAME FORECAST...JUST A DIFFERENT EVENING. 3RD EVENING IN A ROW NOW WITH CONVECTION HAVING DISSIPATED ACROSS THE FA...WITH THE BEST POP CHANCES REMAINING SOUTH THROUGH NORTH OF THE ILM CWA...IN A CLOCKWISE DIRECTION...FOR THE REMAINDER OF THIS EVENING. POPS ACROSS THE FA HAVE AGAIN BEEN RE-ALIGNED FOR THE REMAINDER OF THIS EVENING. LOOKING AT NOCTURNAL DEVELOPMENT OF SHRA/TSRA ACROSS THE ATL LOCAL AND OFFSHORE WATERS DURING THE PRE- DAWN SAT HOURS. THE ONSHORE MOVEMENT OF THIS PCPN WILL ONCE AGAIN OCCUR ESPECIALLY TOWARD SUNRISE SATURDAY. THE CONVECTION ACROSS THE ILM SC WATERS SOUTH OF MYRTLE BEACH WILL HAVE AN IMPULSE ALOFT FURTHER AIDING CONVECTIVE DEVELOPMENT ACROSS THE SC ATL COASTAL AND OFFSHORE WATERS. AS A RESULT...POP CHANCES MAY FURTHER INCREASE TO 30-40 FOR THE COASTAL AREAS SOUTH OF MYRTLE BEACH BY SUNRISE. SOME TWEAKING OF OVERNIGHT MINS AND DEWPOINTS NEEDED BASED ON LATEST OBS...TRENDS...AND HRRR MODEL OUTPUT. OVERNIGHT SKY CONDITIONS TWEAKED FOR LESS CLOUDINESS DURING THIS EVENING. PREVIOUS DISCUSSION................................... AS OF 245 PM FRIDAY...AS EXPECTED DIURNAL CONVECTION IS DEVELOPING ACROSS THE FORECAST AREA. THE SO FAR FAVORED AREAS HAVE BEEN ALONG THE NORTHERN END OF THE COASTAL TROUGH EXTENDING NORTH FROM CONVECTION OFF THE GA COAST AND IN BRUNSWICK COUNTY...NEAR THE INFLECTION POINT OF THE SEA BREEZE. ADDITIONAL ACTIVITY IS STARTING TO DEVELOP ALONG OUTFLOW FROM THE FIRST ROUND OF CONVECTION ACROSS WESTERN PORTIONS OF THE FORECAST AREA. THIS ACTIVITY MAY MELD WITH ANY PIEDMONT TROUGH ACTIVITY THAT STARTS TO DEVELOP DURING THE NEXT FEW HOURS. STORMS WILL CONTINUE TO BE POSSIBLE THROUGH THE REMAINDER OF THE AFTERNOON BUT TRYING TO PICK AREAS WHERE CONVECTION IS FAVORED WILL BE DIFFICULT. THE NORTHERN END OF THE COASTAL TROUGH WILL BE ONE SUCH LOCATION WITH SHOWERS AND THUNDERSTORMS POSSIBLY CONTINUING OVERNIGHT. LOW LEVEL CONVERGENCE ALONG THE BOUNDARY WILL REMAIN IN PLACE AS WILL DEEP MOISTURE. LOW LEVEL INSTABILITY WILL DIMINISHED WITH LOSS OF HEATING BUT DEW POINTS IN THE LOW TO MID 70S AND LOW LEVEL CONVERGENCE MAY BE ALL THAT IS NEEDED. DO NOT THINK COVERAGE WILL BE WIDESPREAD BUT THINK IT WARRANTS A LOW CHC POP FOR AT LEAST THE FIRST PART OF THE OVERNIGHT PERIOD. MOISTURE AND DEBRIS CLOUD WILL AGAIN KEEP LOWS ABOVE CLIMO WITH TEMPS IN THE LOW TO MID 70S. CONVECTION IS LIKELY TO DEVELOP OVER PORTIONS OF THE COASTAL WATERS SOME OF WHICH MAY SPREAD ONSHORE BEFORE QUICKLY WEAKENING AFTER MIDNIGHT. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... AS OF 245 PM FRIDAY...UPPER RIDGE WILL BEGIN TO LOSE ITS INFLUENCE OVER OUR AREA ON SAT AS HEIGHTS FALL AHEAD OF AN APPROACHING COLD FRONT. PWATS CLIMB ABOVE 2.0 INCHES DURING THE DAY AS SOUTHERLY LOW LEVEL FLOW CONTINUES BETWEEN THE BERMUDA HIGH OFFSHORE AND WEAK LOW PRESSURE OVER SOUTHERN GA. THE PREFRONTAL TROUGH AND A DIFFUSE SEA BREEZE WILL SERVE AS THE FOCAL POINTS FOR SCATTERED CONVECTION ON SAT. WILL BUMP UP PCPN CHANCES A BIT BASED ON THE 12Z MODELS BUT KEEP POPS IN THE CHC CATEGORY. DAYTIME HIGHS SAT WILL BE IN THE UPPER 80S...WITH OVERNIGHT LOWS GENERALLY IN THE LOW TO MID 70S. SUNDAY LOOKS EVEN MORE UNSETTLED AS THE COLD FRONT SAGS SOUTHWARD INTO THE CAROLINAS. PWATS IN THE 2.1-2.3 INCH RANGE...COMBINED WITH FRONTAL FORCING AND A WAVE OF LOW PRESSURE DEVELOPING ALONG THE BOUNDARY...WARRANT LIKELY POPS ACROSS OUR CWA DURING THE DAY SUN. THE FRONT WILL LINGER OVER THE FA FOR MUCH OF THE DAY...AND WITH EXPECTED STORM MOTION LESS THAN 10 KT...LOCALIZED FLOODING COULD BECOME A CONCERN IN AREAS THAT RECEIVE HEAVIER DOWNPOURS. ONE THING TO KEEP AN EYE ON IS THE SFC LOW FORECAST TO DEVELOP IN THE VICINITY OF THE FRONT BY SUNDAY AFTN/EVENING. THE GFS/NAM/ECMWF ALL KEEP THE LOWEST PRESSURES OVER LAND RIGHT ALONG THE COAST...SO NO REASON TO EXPECT ANY TROPICAL DEVELOPMENT ATTM. BUT REGARDLESS...THE LATTER HALF OF THE SHORT TERM PERIOD WILL BE QUITE WET. CLOUD COVER AND PCPN SHOULD KEEP HIGHS ON SUN A COUPLE DEGREES COOLER THAN SAT... GENERALLY MID 80S WITH UPPER 80S ACROSS OUR FAR INLAND ZONES. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 245 PM FRIDAY...COLD FRONT SHOULD BE LOCATED RIGHT ALONG THE CAROLINA COAST MONDAY MORNING. EXPECT BEST CONVERGENCE RIGHT ALONG THE COAST AND OFF SHORE ON MONDAY AND THEREFORE WILL KEEP HIGHEST POPS IN THESE LOCATIONS. PCP WATER VALUES WILL BE UP TO 2.2 INCHES ALONG THE COAST EARLY MONDAY BUT WILL DIMINISH DOWN TO 1.5 INCHES THROUGH LATE MONDAY INTO TUES IN A DEEPER DRIER NORTHERLY FLOW. SHORTWAVE RIDING THROUGH THE GREAT LAKES ON MONDAY WILL CONTINUE EAST REACHING DOWN INTO THE CAROLINAS AND PUSHING COLD FRONT FURTHER OFF SHORE THROUGH TUESDAY. SFC HIGH PRESSURE WILL BUILD DOWN BEHIND THE FRONT RIDGING DOWN FROM NEW ENGLAND TUESDAY INTO WED. EXPECT INCREASE IN SUNSHINE THROUGH TUES AND LOWER END POP CHANCES WITH JUST LOCALIZED SEA BREEZE TYPE SHOWERS IF ANY. LOOKS LIKE THE NEXT SYSTEM WILL APPROACH THE CAROLINAS LATE THURS. WINDS AHEAD OF THIS SYSTEM WILL COME BACK AROUND TO THE W-SW WITH A MORE SUMMER- LIKE PATTERN SETTING UP MID WEEK. MID TO UPPER RIDGE BUILDS BACK UP THROUGH THE SOUTHEAST BEFORE NEXT SHORTWAVE PUSHES NEXT COLD FRONT INTO AND THROUGH THE THE CAROLINAS. THE GFS IS ONCE AGAIN FASTER WITH THIS SYSTEM WITH INCREASED POTENTIAL FOR CONVECTION BY LATE THURS INTO FRI...WHILE ECMWF HOLDS IT OFF UNTIL SATURDAY. EXPECT SLIGHTLY LOWER TEMPS ON MONDAY WITH CLOUDS AND SHWRS AROUND. BY TUES SLIGHTLY DRIER AND COOLER WEATHER WILL ARRIVE AS HIGH PRESSURE BUILDS DOWN FROM THE NORTH. THIS SHOULD BRING MORE SEASONABLE WEATHER THROUGH WED WITH A RETURN TO MORE SUMMER-LIKE TEMPS AND WEATHER THURS INTO FRI WITH INCREASED POTENTIAL FOR AFTN CONVECTION. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... AS OF 00Z...MVFR DUE TO FOG LATE OVERNIGHT INTO THE EARLY MORNING HOURS POSSIBLE...ALONG WITH PERIODS OF REDUCED VISIBILITIES IN ANY HEAVY DOWNPOURS. OTHERWISE EXPECT VFR WITH ISOLATED TO SCATTERED SHRA/TSRA ON SATURDAY. OTHER THAN A FEW LIGHT SHOWERS MOVING ACROSS PORTIONS OF THE AREA...THINGS WILL REMAIN FAIRLY QUIET FOR THE REST OF THE EVENING AS FEW/SCT CLOUDS LINGER AND LIGHT SOUTH-SOUTHEAST WINDS PREVAIL. LATE OVERNIGHT INTO THE EARLY MORNING HOURS COULD SEE SOME AREAS OF PATCHY FOG DEVELOP...POTENTIALLY CREATING MVFR INLAND. ON SATURDAY...ANTICIPATE ISOLATED TO SCATTERED SHOWERS EARLY IN THE MORNING AND THROUGHOUT THE DAY...WITH THUNDERSTORMS POSSIBLE. ANY HEAVY DOWNPOUR OVER A TAF SITE COULD CREATE SHORT-LIVED MVFR DUE TO REDUCED VISIBILITIES. SOUTHEAST FLOW WILL PERSIST THROUGHOUT THE DAY WITH SUSTAINED WINDS INCREASING TO AOB 10 KTS. EXTENDED OUTLOOK...A COLD FRONT WILL DROP INTO THE REGION SUNDAY AND MONDAY... WITH A HIGHER RISK FOR SHOWERS AND STORMS BOTH DAYS. THE FRONT STALLS WITH A CONTINUED CHANCE FOR SHOWERS TUESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1045 PM FRIDAY...MAIN UPDATE AT THIS TIME WILL BE AN INCREASE TO POPS ACROSS THE LOCAL WATERS DUE TO THE FIRING OF OFFSHORE CONVECTION 40-60 NM SSE OF CAPE FEAR. ACTIVITY IS MOVING AT A GOOD CLIP AND THUS WILL INDICATE ITS PUSH ACROSS THE ILM COASTAL WATERS EARLIER FROM THE PREVIOUS UPDATE...SOON AFTER MIDNIGHT SATURDAY. LATEST BUOY OBS FROM WITHIN AND AROUND THE VICINITY OF THE ILM COASTAL WATERS INDICATE A SOLID 2 TO OCCASIONALLY 3 FOOT SIGNIFICANT SEAS WITH DOMINANT PERIODS AROUND 7 SECONDS...INDICATIVE OF A WEAK PSEUDO SWELL STILL PRESENT. OBSERVED WINDS REMAIN SE-S AROUND 10 KT. WILL CONTINUE WITH THE OCCASIONAL PHRASEOLOGY FOR WIND SPEEDS UP TO 15 KT. PREVIOUS DISCUSSION............................................... AS OF 730 PM FRIDAY...SAME FORECAST...DIFFERENT NIGHT...FOR THE MOST PART. BUT TIMES ARE CHANGING WITH OCEAN AND MET CONDITIONS TO CHANGE LATER TONIGHT THRU THE UPCOMING WEEKEND. THE REPETITIVE FORECAST OF THE PAST 3 NIGHTS WILL COME TO AN END BASICALLY AFTER TONIGHT. PROGGED SFC PRESSURE PATTERN AND GRADIENT TO YIELD SE-S WINDS AT 10 TO OCCASIONALLY 15 KT. THE 15 KT WILL OCCUR ACROSS THE SOUTHERNMOST PORTIONS OF THE COASTAL WATERS WHERE A WEAK DISTURBANCE ALOFT WILL AID ADDITIONAL NOCTURNAL SHRA/TSRA DEVELOPMENT IN THIS AREA DURING THE PRE-DAWN SATURDAY HOURS. SIGNIFICANT SEAS WILL RUN 2 TO 3 FT...WITH THE LATEST SWAN MODEL RUN WANTING TO PUSH 4 FOOTERS ACROSS THE ILM WATERS LATER TONIGHT BUT DID NOT QUITE BITE INTO YET. PREVIOUS DISCUSSION................................... AS OF 245 PM FRIDAY...BERMUDA HIGH WILL MAINTAIN SOUTH TO SOUTHWEST FLOW OVER THE WATERS THIS AFTERNOON AND OVERNIGHT. GRADIENT WILL REMAIN WEAK THROUGH THE END OF THE PERIOD. SLIGHT ENHANCEMENT TO WINDS DURING AFTERNOON AND EARLY EVENING HOURS WILL KEEP SPEEDS 10 TO 15 KT BUT BY MIDNIGHT SOUTHERLY FLOW WILL BE LESS THAN 10 KT. SEAS IN THE 2 TO 3 FT RANGE THIS AFTERNOON WILL DROP TO 2 FT OVERNIGHT. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 245 PM FRIDAY...EXPECT SOUTH WINDS 10-15 KT OVER THE WATERS FOR MUCH OF THE PERIOD...AS WE REMAIN WEDGED BETWEEN THE BERMUDA HIGH OFFSHORE AND A PREFRONTAL TROUGH INLAND. SEAS WILL BE AROUND 3 FT ON SAT WITH THE PRIMARY WAVE COMPONENT A 5-6 SEC SOUTHERLY WIND CHOP. SOUTH WINDS INCREASE TO 15 KT WITH GUSTS OF 20 KT ON SUN AS THE GRADIENT TIGHTENS AHEAD OF AN APPROACHING COLD FRONT. SEAS WILL BUILD TO 3-4 FT IN RESPONSE. SCT SHOWERS/TSTMS OVER THE WATERS SAT WILL BECOME MORE WIDESPREAD DURING SUN. ONE FEATURE TO NOTE IS AN AREA OF SFC LOW PRESSURE EXPECTED TO DEVELOP IN VICINITY OF THE FRONT ON SUN. AS THIS WAVE OF LOW PRESSURE MOVES UP THE COAST...THERE IS MORE UNCERTAINTY IN THE FORECAST DURING THE LATTER HALF OF THE PERIOD. THE TRACK AND INTENSITY OF THIS FEATURE COULD HAVE BIG IMPACTS ON THE WIND/SEAS FORECAST BY LATE SUN...SO MARINERS SHOULD CONTINUE TO MONITOR THE LATEST UPDATES. WINDS WILL SHIFT OFFSHORE AT THE END OF THE PERIOD BEHIND THE FRONT. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 245 PM FRIDAY...COLD FRONT ALONG THE CAROLINA COAST SHOULD SHIFT OFF SHORE THROUGH TUES AND WEAKEN. WINDS SHOULD VEER A ROUND TO THE NW LATE MON INTO TUES BUT SHOULD BACK AROUND TO THE SW BY WED AS BERMUDA HIGH DOMINATES ONCE AGAIN. LIGHTER OFF SHORE FLOW BEHIND FRONT SHOULD ALLOW SEAS TO DROP FROM 2 TO 4 FT AHEAD OF FRONT EARLY MONDAY DOWN TO 2 TO 3 FT BY MON NIGHT INTO TUES. LIGHTER MORE VARIABLE WINDS AND BENIGN SEAS WILL EXIST TUES INTO WED BEFORE A SLIGHTLY INCREASING RETURN FLOW SETS UP LATE WED INTO THURS AROUND BERMUDA HIGH. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...DCH/BJR NEAR TERM...DCH/III SHORT TERM...BJR LONG TERM...RGZ AVIATION...DL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
807 PM EDT FRI SEP 5 2014 .SYNOPSIS... WARM AND HUMID CONDITIONS WILL PERSIST THROUGH THE WEEKEND. SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE THIS WEEKEND THROUGH MONDAY AS A COLD FRONT DROPS SOUTHEAST AND LINGERS OVER THE AREA AS WEAK UPPER LEVEL IMPULSES PUSH ACROSS THE REGION. A GRADUAL DRYING TREND WILL GET UNDERWAY BY TUESDAY AND PERSIST THROUGH THE MID TO LATE WEEK PERIOD OF NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 715 PM FRIDAY...SAME FORECAST...JUST A DIFFERENT EVENING. 3RD EVENING IN A ROW NOW WITH CONVECTION HAVING DISSIPATED ACROSS THE FA...WITH THE BEST POP CHANCES REMAINING SOUTH THROUGH NORTH OF THE ILM CWA...IN A CLOCKWISE DIRECTION...FOR THE REMAINDER OF THIS EVENING. POPS ACROSS THE FA HAVE AGAIN BEEN RE-ALIGNED FOR THE REMAINDER OF THIS EVENING. LOOKING AT NOCTURNAL DEVELOPMENT OF SHRA/TSRA ACROSS THE ATL LOCAL AND OFFSHORE WATERS DURING THE PRE- DAWN SAT HOURS. THE ONSHORE MOVEMENT OF THIS PCPN WILL ONCE AGAIN OCCUR ESPECIALLY TOWARD SUNRISE SATURDAY. THE CONVECTION ACROSS THE ILM SC WATERS SOUTH OF MYRTLE BEACH WILL HAVE AN IMPULSE ALOFT FURTHER AIDING CONVECTIVE DEVELOPMENT ACROSS THE SC ATL COASTAL AND OFFSHORE WATERS. AS A RESULT...POP CHANCES MAY FURTHER INCREASE TO 30-40 FOR THE COASTAL AREAS SOUTH OF MYRTLE BEACH BY SUNRISE. SOME TWEAKING OF OVERNIGHT MINS AND DEWPOINTS NEEDED BASED ON LATEST OBS...TRENDS...AND HRRR MODEL OUTPUT. OVERNIGHT SKY CONDITIONS TWEAKED FOR LESS CLOUDINESS DURING THIS EVENING. PREVIOUS DISCUSSION.............................................. AS OF 245 PM FRIDAY...AS EXPECTED DIURNAL CONVECTION IS DEVELOPING ACROSS THE FORECAST AREA. THE SO FAR FAVORED AREAS HAVE BEEN ALONG THE NORTHERN END OF THE COASTAL TROUGH EXTENDING NORTH FROM CONVECTION OFF THE GA COAST AND IN BRUNSWICK COUNTY...NEAR THE INFLECTION POINT OF THE SEA BREEZE. ADDITIONAL ACTIVITY IS STARTING TO DEVELOP ALONG OUTFLOW FROM THE FIRST ROUND OF CONVECTION ACROSS WESTERN PORTIONS OF THE FORECAST AREA. THIS ACTIVITY MAY MELD WITH ANY PIEDMONT TROUGH ACTIVITY THAT STARTS TO DEVELOP DURING THE NEXT FEW HOURS. STORMS WILL CONTINUE TO BE POSSIBLE THROUGH THE REMAINDER OF THE AFTERNOON BUT TRYING TO PICK AREAS WHERE CONVECTION IS FAVORED WILL BE DIFFICULT. THE NORTHERN END OF THE COASTAL TROUGH WILL BE ONE SUCH LOCATION WITH SHOWERS AND THUNDERSTORMS POSSIBLY CONTINUING OVERNIGHT. LOW LEVEL CONVERGENCE ALONG THE BOUNDARY WILL REMAIN IN PLACE AS WILL DEEP MOISTURE. LOW LEVEL INSTABILITY WILL DIMINISHED WITH LOSS OF HEATING BUT DEW POINTS IN THE LOW TO MID 70S AND LOW LEVEL CONVERGENCE MAY BE ALL THAT IS NEEDED. DO NOT THINK COVERAGE WILL BE WIDESPREAD BUT THINK IT WARRANTS A LOW CHC POP FOR AT LEAST THE FIRST PART OF THE OVERNIGHT PERIOD. MOISTURE AND DEBRIS CLOUD WILL AGAIN KEEP LOWS ABOVE CLIMO WITH TEMPS IN THE LOW TO MID 70S. CONVECTION IS LIKELY TO DEVELOP OVER PORTIONS OF THE COASTAL WATERS SOME OF WHICH MAY SPREAD ONSHORE BEFORE QUICKLY WEAKENING AFTER MIDNIGHT. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... AS OF 245 PM FRIDAY...UPPER RIDGE WILL BEGIN TO LOSE ITS INFLUENCE OVER OUR AREA ON SAT AS HEIGHTS FALL AHEAD OF AN APPROACHING COLD FRONT. PWATS CLIMB ABOVE 2.0 INCHES DURING THE DAY AS SOUTHERLY LOW LEVEL FLOW CONTINUES BETWEEN THE BERMUDA HIGH OFFSHORE AND WEAK LOW PRESSURE OVER SOUTHERN GA. THE PREFRONTAL TROUGH AND A DIFFUSE SEA BREEZE WILL SERVE AS THE FOCAL POINTS FOR SCATTERED CONVECTION ON SAT. WILL BUMP UP PCPN CHANCES A BIT BASED ON THE 12Z MODELS BUT KEEP POPS IN THE CHC CATEGORY. DAYTIME HIGHS SAT WILL BE IN THE UPPER 80S...WITH OVERNIGHT LOWS GENERALLY IN THE LOW TO MID 70S. SUNDAY LOOKS EVEN MORE UNSETTLED AS THE COLD FRONT SAGS SOUTHWARD INTO THE CAROLINAS. PWATS IN THE 2.1-2.3 INCH RANGE...COMBINED WITH FRONTAL FORCING AND A WAVE OF LOW PRESSURE DEVELOPING ALONG THE BOUNDARY...WARRANT LIKELY POPS ACROSS OUR CWA DURING THE DAY SUN. THE FRONT WILL LINGER OVER THE FA FOR MUCH OF THE DAY...AND WITH EXPECTED STORM MOTION LESS THAN 10 KT...LOCALIZED FLOODING COULD BECOME A CONCERN IN AREAS THAT RECEIVE HEAVIER DOWNPOURS. ONE THING TO KEEP AN EYE ON IS THE SFC LOW FORECAST TO DEVELOP IN THE VICINITY OF THE FRONT BY SUNDAY AFTN/EVENING. THE GFS/NAM/ECMWF ALL KEEP THE LOWEST PRESSURES OVER LAND RIGHT ALONG THE COAST...SO NO REASON TO EXPECT ANY TROPICAL DEVELOPMENT ATTM. BUT REGARDLESS...THE LATTER HALF OF THE SHORT TERM PERIOD WILL BE QUITE WET. CLOUD COVER AND PCPN SHOULD KEEP HIGHS ON SUN A COUPLE DEGREES COOLER THAN SAT... GENERALLY MID 80S WITH UPPER 80S ACROSS OUR FAR INLAND ZONES. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 245 PM FRIDAY...COLD FRONT SHOULD BE LOCATED RIGHT ALONG THE CAROLINA COAST MONDAY MORNING. EXPECT BEST CONVERGENCE RIGHT ALONG THE COAST AND OFF SHORE ON MONDAY AND THEREFORE WILL KEEP HIGHEST POPS IN THESE LOCATIONS. PCP WATER VALUES WILL BE UP TO 2.2 INCHES ALONG THE COAST EARLY MONDAY BUT WILL DIMINISH DOWN TO 1.5 INCHES THROUGH LATE MONDAY INTO TUES IN A DEEPER DRIER NORTHERLY FLOW. SHORTWAVE RIDING THROUGH THE GREAT LAKES ON MONDAY WILL CONTINUE EAST REACHING DOWN INTO THE CAROLINAS AND PUSHING COLD FRONT FURTHER OFF SHORE THROUGH TUESDAY. SFC HIGH PRESSURE WILL BUILD DOWN BEHIND THE FRONT RIDGING DOWN FROM NEW ENGLAND TUESDAY INTO WED. EXPECT INCREASE IN SUNSHINE THROUGH TUES AND LOWER END POP CHANCES WITH JUST LOCALIZED SEA BREEZE TYPE SHOWERS IF ANY. LOOKS LIKE THE NEXT SYSTEM WILL APPROACH THE CAROLINAS LATE THURS. WINDS AHEAD OF THIS SYSTEM WILL COME BACK AROUND TO THE W-SW WITH A MORE SUMMER- LIKE PATTERN SETTING UP MID WEEK. MID TO UPPER RIDGE BUILDS BACK UP THROUGH THE SOUTHEAST BEFORE NEXT SHORTWAVE PUSHES NEXT COLD FRONT INTO AND THROUGH THE THE CAROLINAS. THE GFS IS ONCE AGAIN FASTER WITH THIS SYSTEM WITH INCREASED POTENTIAL FOR CONVECTION BY LATE THURS INTO FRI...WHILE ECMWF HOLDS IT OFF UNTIL SATURDAY. EXPECT SLIGHTLY LOWER TEMPS ON MONDAY WITH CLOUDS AND SHWRS AROUND. BY TUES SLIGHTLY DRIER AND COOLER WEATHER WILL ARRIVE AS HIGH PRESSURE BUILDS DOWN FROM THE NORTH. THIS SHOULD BRING MORE SEASONABLE WEATHER THROUGH WED WITH A RETURN TO MORE SUMMER-LIKE TEMPS AND WEATHER THURS INTO FRI WITH INCREASED POTENTIAL FOR AFTN CONVECTION. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... AS OF 00Z...MVFR DUE TO FOG LATE OVERNIGHT INTO THE EARLY MORNING HOURS POSSIBLE...ALONG WITH PERIODS OF REDUCED VISIBILITIES IN ANY HEAVY DOWNPOURS. OTHERWISE EXPECT VFR WITH ISOLATED TO SCATTERED SHRA/TSRA ON SATURDAY. OTHER THAN A FEW LIGHT SHOWERS MOVING ACROSS PORTIONS OF THE AREA...THINGS WILL REMAIN FAIRLY QUIET FOR THE REST OF THE EVENING AS FEW/SCT CLOUDS LINGER AND LIGHT SOUTH-SOUTHEAST WINDS PREVAIL. LATE OVERNIGHT INTO THE EARLY MORNING HOURS COULD SEE SOME AREAS OF PATCHY FOG DEVELOP...POTENTIALLY CREATING MVFR INLAND. ON SATURDAY...ANTICIPATE ISOLATED TO SCATTERED SHOWERS EARLY IN THE MORNING AND THROUGHOUT THE DAY...WITH THUNDERSTORMS POSSIBLE. ANY HEAVY DOWNPOUR OVER A TAF SITE COULD CREATE SHORT-LIVED MVFR DUE TO REDUCED VISIBILITIES. SOUTHEAST FLOW WILL PERSIST THROUGHOUT THE DAY WITH SUSTAINED WINDS INCREASING TO AOB 10 KTS. EXTENDED OUTLOOK...A COLD FRONT WILL DROP INTO THE REGION SUNDAY AND MONDAY... WITH A HIGHER RISK FOR SHOWERS AND STORMS BOTH DAYS. THE FRONT STALLS WITH A CONTINUED CHANCE FOR SHOWERS TUESDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 730 PM FRIDAY...SAME FORECAST...DIFFERENT NIGHT...FOR THE MOST PART. BUT TIMES ARE CHANGING WITH OCEAN AND MET CONDITIONS TO CHANGE LATER TONIGHT THRU THE UPCOMING WEEKEND. THE REPETITIVE FORECAST OF THE PAST 3 NIGHTS WILL COME TO AN END BASICALLY AFTER TONIGHT. PROGGED SFC PRESSURE PATTERN AND GRADIENT TO YIELD SE-S WINDS AT 10 TO OCCASIONALLY 15 KT. THE 15 KT WILL OCCUR ACROSS THE SOUTHERNMOST PORTIONS OF THE COASTAL WATERS WHERE A WEAK DISTURBANCE ALOFT WILL AID ADDITIONAL NOCTURNAL SHRA/TSRA DEVELOPMENT IN THIS AREA DURING THE PRE-DAWN SATURDAY HOURS. SIGNIFICANT SEAS WILL RUN 2 TO 3 FT...WITH THE LATEST SWAN WANTING TO PUSH 4 FOOTERS LATE TONIGHT BUT DID NOT QUITE BITE INTO YET. PREVIOUS DISCUSSION.............................................. AS OF 245 PM FRIDAY...BERMUDA HIGH WILL MAINTAIN SOUTH TO SOUTHWEST FLOW OVER THE WATERS THIS AFTERNOON AND OVERNIGHT. GRADIENT WILL REMAIN WEAK THROUGH THE END OF THE PERIOD. SLIGHT ENHANCEMENT TO WINDS DURING AFTERNOON AND EARLY EVENING HOURS WILL KEEP SPEEDS 10 TO 15 KT BUT BY MIDNIGHT SOUTHERLY FLOW WILL BE LESS THAN 10 KT. SEAS IN THE 2 TO 3 FT RANGE THIS AFTERNOON WILL DROP TO 2 FT OVERNIGHT. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 245 PM FRIDAY...EXPECT SOUTH WINDS 10-15 KT OVER THE WATERS FOR MUCH OF THE PERIOD...AS WE REMAIN WEDGED BETWEEN THE BERMUDA HIGH OFFSHORE AND A PREFRONTAL TROUGH INLAND. SEAS WILL BE AROUND 3 FT ON SAT WITH THE PRIMARY WAVE COMPONENT A 5-6 SEC SOUTHERLY WIND CHOP. SOUTH WINDS INCREASE TO 15 KT WITH GUSTS OF 20 KT ON SUN AS THE GRADIENT TIGHTENS AHEAD OF AN APPROACHING COLD FRONT. SEAS WILL BUILD TO 3-4 FT IN RESPONSE. SCT SHOWERS/TSTMS OVER THE WATERS SAT WILL BECOME MORE WIDESPREAD DURING SUN. ONE FEATURE TO NOTE IS AN AREA OF SFC LOW PRESSURE EXPECTED TO DEVELOP IN VICINITY OF THE FRONT ON SUN. AS THIS WAVE OF LOW PRESSURE MOVES UP THE COAST...THERE IS MORE UNCERTAINTY IN THE FORECAST DURING THE LATTER HALF OF THE PERIOD. THE TRACK AND INTENSITY OF THIS FEATURE COULD HAVE BIG IMPACTS ON THE WIND/SEAS FORECAST BY LATE SUN...SO MARINERS SHOULD CONTINUE TO MONITOR THE LATEST UPDATES. WINDS WILL SHIFT OFFSHORE AT THE END OF THE PERIOD BEHIND THE FRONT. LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 245 PM FRIDAY...COLD FRONT ALONG THE CAROLINA COAST SHOULD SHIFT OFF SHORE THROUGH TUES AND WEAKEN. WINDS SHOULD VEER A ROUND TO THE NW LATE MON INTO TUES BUT SHOULD BACK AROUND TO THE SW BY WED AS BERMUDA HIGH DOMINATES ONCE AGAIN. LIGHTER OFF SHORE FLOW BEHIND FRONT SHOULD ALLOW SEAS TO DROP FROM 2 TO 4 FT AHEAD OF FRONT EARLY MONDAY DOWN TO 2 TO 3 FT BY MON NIGHT INTO TUES. LIGHTER MORE VARIABLE WINDS AND BENIGN SEAS WILL EXIST TUES INTO WED BEFORE A SLIGHTLY INCREASING RETURN FLOW SETS UP LATE WED INTO THURS AROUND BERMUDA HIGH. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...DCH NEAR TERM...DCH/III SHORT TERM...BJR LONG TERM...RGZ AVIATION...SGL
AREA FORECAST DISCUSSION
NWS BISMARCK ND
152 AM CDT THU SEP 4 2014 .UPDATE... ISSUED AT 155 AM CDT THU SEP 4 2014 WILL ALLOW THE MAJORITY OF THE SEVERE THUNDERSTORM WATCH TO EXPIRE AT 2AM CDT. WILL EXTEND/ISSUE A NEW SEVERE THUNDERSTORM WATCH FOR ONGOING SEVERE STORMS...BASICALLY ALONG I94 AND A COUNTY NORTH AND SOUTH FROM BISMARCK EAST. THIS WILL BE VALID UNTIL 12Z...BUT FULLY EXPECT WE WILL EXPIRE BEFORE ONCE ACTIVITY MOVES OUT OF THE BISMARCK CWA. UPDATE ISSUED AT 106 AM CDT THU SEP 4 2014 CONVECTION CONTINUES TO PUSH EAST...AND HAVE REMOVED ANOTHER TIER OF COUNTIES ON THE WESTERN EDGE OF THE WATCH. AN EXTENSION OR NEW SEVERE THUNDERSTORM WATCH MAY BE NEEDED ACROSS MY EAST. EVALUATING NOW. UPDATE ISSUED AT 1150 PM CDT WED SEP 3 2014 QUICK UPDATE TO REMOVE A FEW COUNTIES ACROSS WESTERN NORTH DAKOTA. SURFACE COLD FRONT HAS MOVED THROUGH THE FAR WEST AND THE SEVERE THREAT HAS DECREASED GREATLY THERE. FARTHER EAST...TWO CONVECTIVE SYSTEMS CONTINUE TO PRODUCE SEVERE WEATHER...ONE OVER EASTERN DUNN AND THE OTHER OVER EASTERN MCLEAN. UPDATED POPS BASED ON LATEST RADAR AND NEAR TERM MODELS. UPDATE ISSUED AT 916 PM CDT WED SEP 3 2014 THUNDERSTORMS ACROSS WESTERN NORTH DAKOTA HAVE INCREASED IN COVERAGE OVER THE PAST COUPLE HOURS. HAVE INCREASED POPS ACROSS THE SOUTHWEST AND CENTRAL PART OF THE STATE WITH THE HRRR AND RAP SHOWING HIGHER THUNDERSTORM CHANCES FOR THOSE LOCATIONS. UPDATE ISSUED AT 640 PM CDT WED SEP 3 2014 ISOLATED SEVERE THUNDERSTORM CONTINUES TO TRACK EAST ACROSS NORTHWEST NORTH DAKOTA...WITH ADDITIONAL STRONG CONVECTION OVER NORTHEAST MONTANA. SURFACE BASED CONVECTION HAS YET TO DEVELOP OVER WESTERN NORTH DAKOTA BUT SUCCESSIVE RUNS OF THE HRRR HAVE INDICATED SCATTERED CONVECTION ACROSS THE SOUTHWEST AND MOVING INTO THE SOUTH CENTRAL. LATEST RUN IS HINTING MORE AT THE CONVECTION IN NORTHEAST MONTANA TRACKING ACROSS THE NORTHWEST AND NORTH CENTRAL. WILL NEED TO MONITOR FOR POSSIBLE CONVECTIVE WATCH THIS EVENING. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 221 PM CDT WED SEP 3 2014 CURRENT SURFACE ANALYSIS PLACES LOW OVER SOUTHEAST MONTANA WITH MOISTURE CONTINUING TO SLOWLY WRAP UP INTO CENTRAL NORTH DAKOTA AHEAD OF IT. UPPER LEVEL ANALYSIS PLACES TROUGH/LOW PUSHING FORWARD INTO EASTERN MONTANA. INITIAL WAVE EJECTING AHEAD OF THE TROUGH CONTINUES TO PRODUCE CONVECTION OVER NORTHEAST MONTANA. FORECAST CHALLENGES FOR TODAY INCLUDE THE SEVERE POTENTIAL LATE TODAY INTO TONIGHT...AND THEN GUSTY WINDS ON THURSDAY. FOR THE REST OF THIS AFTERNOON INTO TONIGHT...UPPER TROUGH WILL CONTINUE ITS EASTWARD PUSH WITH BROAD SCALE LIFT CONTINUING TO INCREASE FROM WEST TO EAST. MOISTURE WILL CONTINUE TO INCREASE AS LOW SLOWLY SHIFTS TOWARDS NORTH CENTRAL SOUTH DAKOTA. INITIAL DISCRETE STORMS THAT DEVELOP WILL ENCOUNTER INCREASING INSTABILITY ALONG WITH IMPRESSIVE DEEP LAYER SHEAR. EXPECT INITIAL STORMS WILL HAVE A MAINLY HAIL THREAT ALONG WITH A STRONG WIND THREAT. AS TIME GOES ON AND STORM DEVELOPMENT WORKS EASTERLY ENCOUNTERING HIGHER MOISTURE...THERE MAY BE A BRIEF TORNADO THREAT IF THE STORMS CAN BE SURFACE BASED. WITH THAT SAID...THE HAIL AND WIND THREAT WILL CONTINUE INTO THE LATE EVENING. FOCUS FOR SEVERE WILL SHIFT OVER MAINLY CENTRAL INTO EASTERN NORTH DAKOTA OVERNIGHT AS PLUME OF STRONG INSTABILITY REMAINS WITH STRONG THETA-E ADVECTION...WHILE OVER THE WEST ATMOSPHERE WILL STABILIZE. STORMS SHOULD ALL BE PUSHED OFF TO THE EAST BY SUNRISE WITH SHOWERS LINGERING. ON THURSDAY...SOME SHOWERS WILL REMAIN PRIMARILY OVER THE NORTHERN AND EASTERN PART OF THE STATE AS UPPER TROUGH MAKES ITS WAY EAST. PRIMARY CONCERN WILL BE GUSTY WEST TO NORTHWESTERLY WINDS DEVELOPING AS COLD AIR POURS INTO THE AREA WITH TIGHT PRESSURE GRADIENT AS LOW SHIFTS INTO MINNESOTA. STRONGEST WINDS LOOK TO BE OVER SOUTHWEST NORTH DAKOTA IN THE MORNING...WITH WINDS DIMINISHING IN THE AFTERNOON AS GRADIENT RELAXES AND COLD AIR ADVECTION DECREASES. TEMPERATURES WILL BE SEASONABLY COOL WITH MANY LOCATIONS AROUND 10-15 DEGREES BELOW AVERAGE. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 221 PM CDT WED SEP 3 2014 A NORTHWEST FLOW ALOFT IS MAINTAINED THURSDAY NIGHT INTO SATURDAY...THEN TRANSITIONS TO A ZONAL FLOW SUNDAY INTO WEDNESDAY. A MORE ACTIVE PERIOD WILL EVOLVE DURING THE ZONAL FLOW PERIOD AS A STRONG SHORTWAVE TROUGH AND ASSOCIATED POTENT COLD FRONT IS SLATED TO SWEEP THROUGH TUESDAY INTO WEDNESDAY...WITH SEVERE WEATHER POSSIBLE. GUSTY NORTHWEST WINDS THURSDAY EVENING WILL QUICKLY SUBSIDE AS A SURFACE HIGH PRESSURE SLIDES ACROSS SOUTHWEST NORTH DAKOTA EARLY THURSDAY NIGHT AND INTO CENTRAL SOUTH DAKOTA BY 12Z FRIDAY. A CLEAR SKY...GOOD RADIATIONAL COOLING...AND DEWPOINTS IN THE UPPER 30S LOOK REASONABLE TO SUPPORT OVERNIGHT LOWS IN THE UPPER 30S ACROSS THE SOUTHWEST...ESPECIALLY OVER THE NORMAL COLDER LOCATIONS SUCH AS HETTINGER. HENCE HAVE LOWERED MINIMUM TEMPERATURES INTO THE UPPER 30S UNDER THIS WEATHER PATTERN. OVERALL...A QUIET/PLEASANT WEATHER PATTERN CONTINUES FRIDAY/SATURDAY WITH A SLOW MODERATING TREND. H85 TEMPS BEGIN TO WARM LEADING TO HIGHS INTO THE 70S SATURDAY AND SUNDAY. THERE WILL BE A SUBTLE DRY COLD FRONTAL PASSAGE SATURDAY AFTERNOON...HOWEVER OTHER THAN A WINDSHIFT TO THE NORTHWEST...NOT EXPECTING MUCH OF A TEMPERATURE CHANGE. A MORE ACTIVE WEATHER PATTERN SLOWLY BEGINS TO EMERGE SUNDAY NIGHT AS A WEAK SHORTWAVE SLIDES THROUGH WITH WARM AIR ADVECTION PROCESSES TAKING OVER. A SLIGHT CHANCE OF SHOWERS/THUNDERSTORMS ARE POSSIBLE SUNDAY NIGHT INTO MONDAY MAINLY FOR THE JAMES RIVER VALLEY. THE WARMEST DAY WILL BE MONDAY WITH HIGHS REACHING BETWEEN 75 AND 85. THIS WILL BE FOLLOWED BY A STRONG COLD FRONT WHICH WILL APPROACH NORTHWEST NORTH DAKOTA TUESDAY MORNING AND THEN SWEEP THROUGH TUESDAY AFTERNOON/EVENING. A STRONG H85 BAROCLINIC ZONE SHIFTS THROUGH TUESDAY NIGHT WITH THE 0C TO -2C ISOTHERM SETTLING INTO CENTRAL NORTH DAKOTA WEDNESDAY. THIS TREND SETS THE STAGE FOR MUCH COLDER AIR WEDNESDAY THROUGH FRIDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY EVENING) ISSUED AT 106 AM CDT THU SEP 4 2014 SCATTERED CONVECTION THIS EVENING CONTINUES EAST ACROSS CENTRAL NORTH DAKOTA AS A COLD FRONT MOVES THROUGH THE AREA. FLOW WILL TURN WEST TO NORTHWEST LATE TONIGHT AND THURSDAY WITH AREAS OF IFR-MVFR CLOUDINESS MOST LOCATIONS. STRONG NORTHWEST WINDS ON THURSDAY WITH THE STRONGEST 20 TO 35 MPH AT KDIK. && .BIS WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM 6 AM THIS MORNING TO 4 PM MDT THIS AFTERNOON FOR NDZ031>033-040-041-043-044. && $$ UPDATE...NH SHORT TERM...JJS LONG TERM...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
105 AM CDT THU SEP 4 2014 .UPDATE... ISSUED AT 106 AM CDT THU SEP 4 2014 CONVECTION CONTINUES TO PUSH EAST...AND HAVE REMOVED ANOTHER TIER OF COUNTIES ON THE WESTERN EDGE OF THE WATCH. AN EXTENSION OR NEW SEVERE THUNDERSTORM WATCH MAY BE NEEDED ACROSS MY EAST. EVALUATING NOW. UPDATE ISSUED AT 1150 PM CDT WED SEP 3 2014 QUICK UPDATE TO REMOVE A FEW COUNTIES ACROSS WESTERN NORTH DAKOTA. SURFACE COLD FRONT HAS MOVED THROUGH THE FAR WEST AND THE SEVERE THREAT HAS DECREASED GREATLY THERE. FARTHER EAST...TWO CONVECTIVE SYSTEMS CONTINUE TO PRODUCE SEVERE WEATHER...ONE OVER EASTERN DUNN AND THE OTHER OVER EASTERN MCLEAN. UPDATED POPS BASED ON LATEST RADAR AND NEAR TERM MODELS. UPDATE ISSUED AT 916 PM CDT WED SEP 3 2014 THUNDERSTORMS ACROSS WESTERN NORTH DAKOTA HAVE INCREASED IN COVERAGE OVER THE PAST COUPLE HOURS. HAVE INCREASED POPS ACROSS THE SOUTHWEST AND CENTRAL PART OF THE STATE WITH THE HRRR AND RAP SHOWING HIGHER THUNDERSTORM CHANCES FOR THOSE LOCATIONS. UPDATE ISSUED AT 640 PM CDT WED SEP 3 2014 ISOLATED SEVERE THUNDERSTORM CONTINUES TO TRACK EAST ACROSS NORTHWEST NORTH DAKOTA...WITH ADDITIONAL STRONG CONVECTION OVER NORTHEAST MONTANA. SURFACE BASED CONVECTION HAS YET TO DEVELOP OVER WESTERN NORTH DAKOTA BUT SUCCESSIVE RUNS OF THE HRRR HAVE INDICATED SCATTERED CONVECTION ACROSS THE SOUTHWEST AND MOVING INTO THE SOUTH CENTRAL. LATEST RUN IS HINTING MORE AT THE CONVECTION IN NORTHEAST MONTANA TRACKING ACROSS THE NORTHWEST AND NORTH CENTRAL. WILL NEED TO MONITOR FOR POSSIBLE CONVECTIVE WATCH THIS EVENING. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 221 PM CDT WED SEP 3 2014 CURRENT SURFACE ANALYSIS PLACES LOW OVER SOUTHEAST MONTANA WITH MOISTURE CONTINUING TO SLOWLY WRAP UP INTO CENTRAL NORTH DAKOTA AHEAD OF IT. UPPER LEVEL ANALYSIS PLACES TROUGH/LOW PUSHING FORWARD INTO EASTERN MONTANA. INITIAL WAVE EJECTING AHEAD OF THE TROUGH CONTINUES TO PRODUCE CONVECTION OVER NORTHEAST MONTANA. FORECAST CHALLENGES FOR TODAY INCLUDE THE SEVERE POTENTIAL LATE TODAY INTO TONIGHT...AND THEN GUSTY WINDS ON THURSDAY. FOR THE REST OF THIS AFTERNOON INTO TONIGHT...UPPER TROUGH WILL CONTINUE ITS EASTWARD PUSH WITH BROAD SCALE LIFT CONTINUING TO INCREASE FROM WEST TO EAST. MOISTURE WILL CONTINUE TO INCREASE AS LOW SLOWLY SHIFTS TOWARDS NORTH CENTRAL SOUTH DAKOTA. INITIAL DISCRETE STORMS THAT DEVELOP WILL ENCOUNTER INCREASING INSTABILITY ALONG WITH IMPRESSIVE DEEP LAYER SHEAR. EXPECT INITIAL STORMS WILL HAVE A MAINLY HAIL THREAT ALONG WITH A STRONG WIND THREAT. AS TIME GOES ON AND STORM DEVELOPMENT WORKS EASTERLY ENCOUNTERING HIGHER MOISTURE...THERE MAY BE A BRIEF TORNADO THREAT IF THE STORMS CAN BE SURFACE BASED. WITH THAT SAID...THE HAIL AND WIND THREAT WILL CONTINUE INTO THE LATE EVENING. FOCUS FOR SEVERE WILL SHIFT OVER MAINLY CENTRAL INTO EASTERN NORTH DAKOTA OVERNIGHT AS PLUME OF STRONG INSTABILITY REMAINS WITH STRONG THETA-E ADVECTION...WHILE OVER THE WEST ATMOSPHERE WILL STABILIZE. STORMS SHOULD ALL BE PUSHED OFF TO THE EAST BY SUNRISE WITH SHOWERS LINGERING. ON THURSDAY...SOME SHOWERS WILL REMAIN PRIMARILY OVER THE NORTHERN AND EASTERN PART OF THE STATE AS UPPER TROUGH MAKES ITS WAY EAST. PRIMARY CONCERN WILL BE GUSTY WEST TO NORTHWESTERLY WINDS DEVELOPING AS COLD AIR POURS INTO THE AREA WITH TIGHT PRESSURE GRADIENT AS LOW SHIFTS INTO MINNESOTA. STRONGEST WINDS LOOK TO BE OVER SOUTHWEST NORTH DAKOTA IN THE MORNING...WITH WINDS DIMINISHING IN THE AFTERNOON AS GRADIENT RELAXES AND COLD AIR ADVECTION DECREASES. TEMPERATURES WILL BE SEASONABLY COOL WITH MANY LOCATIONS AROUND 10-15 DEGREES BELOW AVERAGE. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 221 PM CDT WED SEP 3 2014 A NORTHWEST FLOW ALOFT IS MAINTAINED THURSDAY NIGHT INTO SATURDAY...THEN TRANSITIONS TO A ZONAL FLOW SUNDAY INTO WEDNESDAY. A MORE ACTIVE PERIOD WILL EVOLVE DURING THE ZONAL FLOW PERIOD AS A STRONG SHORTWAVE TROUGH AND ASSOCIATED POTENT COLD FRONT IS SLATED TO SWEEP THROUGH TUESDAY INTO WEDNESDAY...WITH SEVERE WEATHER POSSIBLE. GUSTY NORTHWEST WINDS THURSDAY EVENING WILL QUICKLY SUBSIDE AS A SURFACE HIGH PRESSURE SLIDES ACROSS SOUTHWEST NORTH DAKOTA EARLY THURSDAY NIGHT AND INTO CENTRAL SOUTH DAKOTA BY 12Z FRIDAY. A CLEAR SKY...GOOD RADIATIONAL COOLING...AND DEWPOINTS IN THE UPPER 30S LOOK REASONABLE TO SUPPORT OVERNIGHT LOWS IN THE UPPER 30S ACROSS THE SOUTHWEST...ESPECIALLY OVER THE NORMAL COLDER LOCATIONS SUCH AS HETTINGER. HENCE HAVE LOWERED MINIMUM TEMPERATURES INTO THE UPPER 30S UNDER THIS WEATHER PATTERN. OVERALL...A QUIET/PLEASANT WEATHER PATTERN CONTINUES FRIDAY/SATURDAY WITH A SLOW MODERATING TREND. H85 TEMPS BEGIN TO WARM LEADING TO HIGHS INTO THE 70S SATURDAY AND SUNDAY. THERE WILL BE A SUBTLE DRY COLD FRONTAL PASSAGE SATURDAY AFTERNOON...HOWEVER OTHER THAN A WINDSHIFT TO THE NORTHWEST...NOT EXPECTING MUCH OF A TEMPERATURE CHANGE. A MORE ACTIVE WEATHER PATTERN SLOWLY BEGINS TO EMERGE SUNDAY NIGHT AS A WEAK SHORTWAVE SLIDES THROUGH WITH WARM AIR ADVECTION PROCESSES TAKING OVER. A SLIGHT CHANCE OF SHOWERS/THUNDERSTORMS ARE POSSIBLE SUNDAY NIGHT INTO MONDAY MAINLY FOR THE JAMES RIVER VALLEY. THE WARMEST DAY WILL BE MONDAY WITH HIGHS REACHING BETWEEN 75 AND 85. THIS WILL BE FOLLOWED BY A STRONG COLD FRONT WHICH WILL APPROACH NORTHWEST NORTH DAKOTA TUESDAY MORNING AND THEN SWEEP THROUGH TUESDAY AFTERNOON/EVENING. A STRONG H85 BAROCLINIC ZONE SHIFTS THROUGH TUESDAY NIGHT WITH THE 0C TO -2C ISOTHERM SETTLING INTO CENTRAL NORTH DAKOTA WEDNESDAY. THIS TREND SETS THE STAGE FOR MUCH COLDER AIR WEDNESDAY THROUGH FRIDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY EVENING) ISSUED AT 106 AM CDT THU SEP 4 2014 SCATTERED CONVECTION THIS EVENING CONTINUES EAST ACROSS CENTRAL NORTH DAKOTA AS A COLD FRONT MOVES THROUGH THE AREA. FLOW WILL TURN WEST TO NORTHWEST LATE TONIGHT AND THURSDAY WITH AREAS OF IFR-MVFR CLOUDINESS MOST LOCATIONS. STRONG NORTHWEST WINDS ON THURSDAY WITH THE STRONGEST 20 TO 35 MPH AT KDIK. && .BIS WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM 6 AM THIS MORNING TO 4 PM MDT THIS AFTERNOON FOR NDZ031>033-040-041-043-044. && $$ UPDATE...NH SHORT TERM...JJS LONG TERM...KS
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1147 PM CDT WED SEP 3 2014 .UPDATE... ISSUED AT 1150 PM CDT WED SEP 3 2014 QUICK UPDATE TO REMOVE A FEW COUNTIES ACROSS WESTERN NORTH DAKOTA. SURFACE COLD FRONT HAS MOVED THROUGH THE FAR WEST AND THE SEVERE THREAT HAS DECREASED GREATLY THERE. FARTHER EAST...TWO CONVECTIVE SYSTEMS CONTINUE TO PRODUCE SEVERE WEATHER...ONE OVER EASTERN DUNN AND THE OTHER OVER EASTERN MCLEAN. UPDATED POPS BASED ON LATEST RADAR AND NEAR TERM MODELS. UPDATE ISSUED AT 916 PM CDT WED SEP 3 2014 THUNDERSTORMS ACROSS WESTERN NORTH DAKOTA HAVE INCREASED IN COVERAGE OVER THE PAST COUPLE HOURS. HAVE INCREASED POPS ACROSS THE SOUTHWEST AND CENTRAL PART OF THE STATE WITH THE HRRR AND RAP SHOWING HIGHER THUNDERSTORM CHANCES FOR THOSE LOCATIONS. UPDATE ISSUED AT 640 PM CDT WED SEP 3 2014 ISOLATED SEVERE THUNDERSTORM CONTINUES TO TRACK EAST ACROSS NORTHWEST NORTH DAKOTA...WITH ADDITIONAL STRONG CONVECTION OVER NORTHEAST MONTANA. SURFACE BASED CONVECTION HAS YET TO DEVELOP OVER WESTERN NORTH DAKOTA BUT SUCCESSIVE RUNS OF THE HRRR HAVE INDICATED SCATTERED CONVECTION ACROSS THE SOUTHWEST AND MOVING INTO THE SOUTH CENTRAL. LATEST RUN IS HINTING MORE AT THE CONVECTION IN NORTHEAST MONTANA TRACKING ACROSS THE NORTHWEST AND NORTH CENTRAL. WILL NEED TO MONITOR FOR POSSIBLE CONVECTIVE WATCH THIS EVENING. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 221 PM CDT WED SEP 3 2014 CURRENT SURFACE ANALYSIS PLACES LOW OVER SOUTHEAST MONTANA WITH MOISTURE CONTINUING TO SLOWLY WRAP UP INTO CENTRAL NORTH DAKOTA AHEAD OF IT. UPPER LEVEL ANALYSIS PLACES TROUGH/LOW PUSHING FORWARD INTO EASTERN MONTANA. INITIAL WAVE EJECTING AHEAD OF THE TROUGH CONTINUES TO PRODUCE CONVECTION OVER NORTHEAST MONTANA. FORECAST CHALLENGES FOR TODAY INCLUDE THE SEVERE POTENTIAL LATE TODAY INTO TONIGHT...AND THEN GUSTY WINDS ON THURSDAY. FOR THE REST OF THIS AFTERNOON INTO TONIGHT...UPPER TROUGH WILL CONTINUE ITS EASTWARD PUSH WITH BROAD SCALE LIFT CONTINUING TO INCREASE FROM WEST TO EAST. MOISTURE WILL CONTINUE TO INCREASE AS LOW SLOWLY SHIFTS TOWARDS NORTH CENTRAL SOUTH DAKOTA. INITIAL DISCRETE STORMS THAT DEVELOP WILL ENCOUNTER INCREASING INSTABILITY ALONG WITH IMPRESSIVE DEEP LAYER SHEAR. EXPECT INITIAL STORMS WILL HAVE A MAINLY HAIL THREAT ALONG WITH A STRONG WIND THREAT. AS TIME GOES ON AND STORM DEVELOPMENT WORKS EASTERLY ENCOUNTERING HIGHER MOISTURE...THERE MAY BE A BRIEF TORNADO THREAT IF THE STORMS CAN BE SURFACE BASED. WITH THAT SAID...THE HAIL AND WIND THREAT WILL CONTINUE INTO THE LATE EVENING. FOCUS FOR SEVERE WILL SHIFT OVER MAINLY CENTRAL INTO EASTERN NORTH DAKOTA OVERNIGHT AS PLUME OF STRONG INSTABILITY REMAINS WITH STRONG THETA-E ADVECTION...WHILE OVER THE WEST ATMOSPHERE WILL STABILIZE. STORMS SHOULD ALL BE PUSHED OFF TO THE EAST BY SUNRISE WITH SHOWERS LINGERING. ON THURSDAY...SOME SHOWERS WILL REMAIN PRIMARILY OVER THE NORTHERN AND EASTERN PART OF THE STATE AS UPPER TROUGH MAKES ITS WAY EAST. PRIMARY CONCERN WILL BE GUSTY WEST TO NORTHWESTERLY WINDS DEVELOPING AS COLD AIR POURS INTO THE AREA WITH TIGHT PRESSURE GRADIENT AS LOW SHIFTS INTO MINNESOTA. STRONGEST WINDS LOOK TO BE OVER SOUTHWEST NORTH DAKOTA IN THE MORNING...WITH WINDS DIMINISHING IN THE AFTERNOON AS GRADIENT RELAXES AND COLD AIR ADVECTION DECREASES. TEMPERATURES WILL BE SEASONABLY COOL WITH MANY LOCATIONS AROUND 10-15 DEGREES BELOW AVERAGE. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 221 PM CDT WED SEP 3 2014 A NORTHWEST FLOW ALOFT IS MAINTAINED THURSDAY NIGHT INTO SATURDAY...THEN TRANSITIONS TO A ZONAL FLOW SUNDAY INTO WEDNESDAY. A MORE ACTIVE PERIOD WILL EVOLVE DURING THE ZONAL FLOW PERIOD AS A STRONG SHORTWAVE TROUGH AND ASSOCIATED POTENT COLD FRONT IS SLATED TO SWEEP THROUGH TUESDAY INTO WEDNESDAY...WITH SEVERE WEATHER POSSIBLE. GUSTY NORTHWEST WINDS THURSDAY EVENING WILL QUICKLY SUBSIDE AS A SURFACE HIGH PRESSURE SLIDES ACROSS SOUTHWEST NORTH DAKOTA EARLY THURSDAY NIGHT AND INTO CENTRAL SOUTH DAKOTA BY 12Z FRIDAY. A CLEAR SKY...GOOD RADIATIONAL COOLING...AND DEWPOINTS IN THE UPPER 30S LOOK REASONABLE TO SUPPORT OVERNIGHT LOWS IN THE UPPER 30S ACROSS THE SOUTHWEST...ESPECIALLY OVER THE NORMAL COLDER LOCATIONS SUCH AS HETTINGER. HENCE HAVE LOWERED MINIMUM TEMPERATURES INTO THE UPPER 30S UNDER THIS WEATHER PATTERN. OVERALL...A QUIET/PLEASANT WEATHER PATTERN CONTINUES FRIDAY/SATURDAY WITH A SLOW MODERATING TREND. H85 TEMPS BEGIN TO WARM LEADING TO HIGHS INTO THE 70S SATURDAY AND SUNDAY. THERE WILL BE A SUBTLE DRY COLD FRONTAL PASSAGE SATURDAY AFTERNOON...HOWEVER OTHER THAN A WINDSHIFT TO THE NORTHWEST...NOT EXPECTING MUCH OF A TEMPERATURE CHANGE. A MORE ACTIVE WEATHER PATTERN SLOWLY BEGINS TO EMERGE SUNDAY NIGHT AS A WEAK SHORTWAVE SLIDES THROUGH WITH WARM AIR ADVECTION PROCESSES TAKING OVER. A SLIGHT CHANCE OF SHOWERS/THUNDERSTORMS ARE POSSIBLE SUNDAY NIGHT INTO MONDAY MAINLY FOR THE JAMES RIVER VALLEY. THE WARMEST DAY WILL BE MONDAY WITH HIGHS REACHING BETWEEN 75 AND 85. THIS WILL BE FOLLOWED BY A STRONG COLD FRONT WHICH WILL APPROACH NORTHWEST NORTH DAKOTA TUESDAY MORNING AND THEN SWEEP THROUGH TUESDAY AFTERNOON/EVENING. A STRONG H85 BAROCLINIC ZONE SHIFTS THROUGH TUESDAY NIGHT WITH THE 0C TO -2C ISOTHERM SETTLING INTO CENTRAL NORTH DAKOTA WEDNESDAY. THIS TREND SETS THE STAGE FOR MUCH COLDER AIR WEDNESDAY THROUGH FRIDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 640 PM CDT WED SEP 3 2014 SCATTERED CONVECTION THIS EVENING ACROSS WESTERN AND CENTRAL NORTH DAKOTA AS A COLD FRONT MOVES THROUGH THE AREA. FLOW WILL TURN WEST TO NORTHWEST LATE TONIGHT AND THURSDAY WITH AREAS OF MVFR CLOUDINESS...ESPECIALLY ACROSS THE NORTH...KISN TO KMOT. STRONG NORTHWEST WINDS ON THURSDAY WITH THE STRONGEST 20 TO 35 MPH AT KDIK. && .BIS WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM 6 AM TO 4 PM MDT THURSDAY FOR NDZ031>033-040- 041-043-044. && $$ UPDATE...NH SHORT TERM...JJS LONG TERM...KS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1144 PM CDT WED SEP 3 2014 .UPDATE... ISSUED AT 1144 PM CDT WED SEP 3 2014 SEVERE STORMS CONTINUE TO APPROACH THE REGION FROM THE WEST. THE STRONGEST STORMS ARE PROPAGATING EAST/SOUTHEAST...INTO THE STRONGER INSTABILITY. ANTICIPATE THESE STORMS WILL CONTINUE TO PROPAGATE TOWARD SOUTHEAST NORTH DAKOTA. HI-RES MODEL GUIDANCE (MPX HOPWRF...HRRR) INDICATES A RELATIVELY HIGH PROBABILITY THAT THESE STORMS WILL REMAIN SEVERE AS THEY MOVE ACROSS THE SOUTHERN FA OVER THE NEXT SEVERAL HOURS (AND LIKEWISE A HIGHER PROBABILITY THAT A SEVERE THUNDERSTORM WATCH COULD BE ISSUED BY 2AM). LOOKS LIKE LARGE HAIL...AND SOME SORT OF BOWING SEGMENTS (STRONG WIND GUSTS) WILL OCCUR. UPDATE ISSUED AT 952 PM CDT WED SEP 3 2014 SEVERE STORMS HAVE DEVELOPED ACROSS WESTERN NORTH DAKOTA...MOSTLY AS EXPECTED. THIS AREA OF STORMS SHOULD CONTINUE TO PROPAGATE EASTWARD THROUGH THE OVERNIGHT HOURS. ADDITIONAL STORMS SHOULD ALSO DEVELOP ACROSS SOUTHERN NORTH DAKOTA. GIVEN WHERE THE STRONGEST INSTABILITY WILL BE LOCATED...THINKING THE BEST CHANCES FOR THUNDERSTORMS (AND SEVERE THUNDERSTORMS) WILL BE ACROSS THE SOUTHERN HALF OF THE FA. IN FACT...THE CURRENT ACTIVITY ACROSS WESTERN NORTH DAKOTA (AT LEAST THE STRONGER REFLECTIVITY) IS GRADUALLY SHIFTING SOUTHWARD WITH TIME. LARGE HAIL AND STRONG WIND GUSTS (500MB JET ABOVE 50 KTS) WILL BE THE MAIN THREATS. ADJUSTED TIMING OF POPS BASED ON LATEST TRENDS AND HI-RES MODEL GUIDANCE...AND KEPT THE SEVERE MENTION ACROSS THE SOUTHERN FA. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT) ISSUED AT 319 PM CDT WED SEP 3 2014 CONCERN REMAINS HOW FAR NORTH CONVECTION GETS INTO SOUTHEASTERN FCST AREA LATE THIS AFTN/EVE AND HOW MUCH CONVECTION/PRECIP DEVELOPS IN WRN ND THIS EVE AND MOVES EAST OVERNIGHT. RAP/HRRR AND NAM12 HAVE BEEN DOING REASONABLE IN THEIR DEPICTION OF CONVECTION IN CNTRL MN NORTH OF THE WARM FRONT. OBS INDICATE LIKELY WARM FRONT FROM ABOUT WATERTOWN TO CANBY MN THEN TOWARD HUTCHINSON MN THEN TO THE TWIN CITIES. IT HAS BEEN MOVING NORTHWARD. RAP SHOWS LOW LEVEL JET FEEDING INTO BAND OF STORMS THAT HAS BEEN SLOWLY LIFTING NORTHEAST THRU CNTRL MN TURNING A BIT MORE SOUTHWEST TO NORTHEAST ORIENTATION AFTER 00Z AND THUS FOCUS OF PRECIP WILL SHIFT EAST. REGIONAL RADARS SHOWING NOW SOME DEVELOPING SOUTHWEST OF LINE INTO THE WARM SECTOR WEST OF WILMAR..THOUGH IT IS WEAK NOW. IDEA FROM EARLIER SWOMCD IS FOR ACTIVITY TO INCREASE IN THE AREA NORTHWEST AND WEST OF THE TWIN CITIES NEXT FEW HOURS. IT DOES APPEAR MORE AND MORE LIKELY THAT ONLY THE FAR SOUTHEASTERN FCST AREA WILL HAVE ANY IMPACTS FROM THESE STORMS AND THAT MOST WILL STAY JUST SOUTHEAST OF OUR AREA. THUS TRIMMED POPS SOME BUT DID KEEP SEVERE MENTION AT LEAST FOR NOW INTO THE EVE IN FAR SOUTHEASTERN FCST AREA. REST OF THE AREA DRY THRU MID EVENING. THEN WHAT HAPPENS IS IN QUESTION. RAP SHOWS A DEVELOPING LOW LEVEL JET AND QUITE STRONG 850 THETA-E ADVECTION AND AN AREA OF SHOWWALTERS TO -10C MOVING NORTH INTO SE ND 06Z AND JUST AFTERWARDS. MAIN FORCING WILL BE MORE NORTHWEST TOWARD UPPER LOW IN SOUTHEASTERN SASK. MODELS NOT EXCITED ABOUT TOO MUCH IN THIS ELEVATED UNSTABLE LAYER AS IT MOVES INTO SE ND OVERNIGHT BUT AREA IS IN FAVORABLE POSITION OF LOW LEVEL JET (LEFT QUAD) AND STRONG INSTABILITY GRADIENT SO WOULDNT BE SURPRISED IF TSTMS DEVELOP OVERNIGHT AHD OF COLD FRONT IN A MORE WIDESPREAD FASHION THAN MODEL ADVERTISES. ANYHOW....DID KEEP SEVERE MENTION OVERNIGHT PER DAY 1 SLIGHT RISK OVER CNTRL INTO SE ND AND THIS CAN BE ADJUSTED AS NEEDED. IF 850 MB SHOWWALTERS AND LOW LEVEL JET ARE ACCURATE THEN WOULD BE ENOUGH FOR SOME SEVERE HAILERS. MU CAPES IN THE 2500 J/KG RANGE IN SE ND. LESS INSTABILITY FARTHER NORTH BUT MAYBE A BIT BETTER CHC OF A BAND OF SHOWERS/STORMS LATE NIGHT INTO EARLY THURSDAY. PRECIP WILL EXIT NW MN THURSDAY AFTN...THEN DRIER AND COOLER AIR MOVES IN THU NIGHT. THOUGH SOME WRAPAROUND CLOUD COVER PSBL ESP IN NW MN. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 319 PM CDT WED SEP 3 2014 HIGH PRESSURE IN CONTROL FRIDAY WITH LIKELY DIURNAL CU WITH COOLER AIR ALOFT. FOR FRI NIGHT INTO TUESDAY... A NORTHWEST FLOW PATTERN ALOFT...VOID OF ANY APPRECIABLE MOISTURE TRANSPORT INTO THE AREA...WILL KEEP A DRY AND COOL AIR MASS IN PLACE THROUGH THE UPCOMING WEEKEND. THE UPPER AIR PATTERN BECOMES ZONAL SUNDAY AND TURNS TO THE SOUTHWEST SUNDAY NIGHT...WITH LEE SIDE LOW PRESSURE MOVING INTO THE PLAINS ON MONDAY. THIS WILL OPEN UP THE GULF FOR INCREASED MOISTURE TRANSPORT INTO THE AREA AND BRING MORE ACTIVE WEATHER FOR THE EARLY TO MIDDLE PART OF NEXT WEEK. TEMPERATURES WILL TYPICALLY BE RIGHT AT OR SLIGHTLY COOLER THAN SEASONAL NORMS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1144 PM CDT WED SEP 3 2014 SHOWERS AND THUNDERSTORMS WILL MOVE THROUGH THE REGION TONIGHT. USED THE LATEST RADAR IMAGERY AND HI-RES MODEL GUIDANCE FOR TIMING. THIS ACTIVITY IS EXPECTED TO AFFECT EACH TAF SITE FOR AT LEAST A BRIEF PERIOD OF TIME. THE STRONG ACTIVITY WILL BE ACROSS SOUTHEAST NORTH DAKOTA...AND MAY AFFECT KFAR. BEHIND THIS PRECIP...ANTICIPATE A PERIOD OF MVFR CIGS FOR A FEW HOURS. THEN...VFR CONDITIONS AS WINDS BECOME WESTERLY (AND GUSTY). && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...TG SHORT TERM...RIDDLE LONG TERM... RIDDLE/SPEICHER AVIATION...TG
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
617 PM EDT THU SEP 4 2014 .SYNOPSIS... A LOW WILL MOVE ACROSS ONTARIO TONIGHT AND INTO QUEBEC FRIDAY AND FRIDAY NIGHT. A COLD FRONT ASSOCIATED WITH THE LOW WILL MOVE ACROSS THE AREA FRIDAY NIGHT. A RIDGE WILL BUILD IN SATURDAY NIGHT AND LAST INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... RADAR RETURNS GETTING AWFULLY CLOSE TO KTOL. THIS ACTIVITY SHOULD DISSIPATE AFTER SUNSET BUT HAVE ADDED A SMALL MENTION TO LUCAS CO. MADE THE SKY FORECAST MORE OPTIMISTIC FOR EASTERN AREAS. PREVIOUS...THE CUMULUS WILL DISSIPATE QUICKLY. SOME MID AND HIGH CLOUDS WILL BE AROUND. PARTLY CLOUDY SHOULD HANDLE IT. WENT TOWARD THE WARMER GUIDANCE FOR LOWS BECAUSE OF THE DEW POINTS AND SOME WIND. THE HRRR MODEL TRIES TO BRING SOME SPRINKLES OR SHOWERS INTO NW OH BY EVENING...THIS IS THE REMNANTS OF THE SYSTEM FROM EARLIER. THIS AREA IS DECREASING...WILL KEEP IT DRY. THE NAM ESPECIALLY TRIES TO HINT AT SOME SHOWERS DEVELOPING OVER NORTHWEST OHIO TOWARD DAYBREAK FRIDAY. THE GFS KIND OF HINTS AT THAT TOO. AT THIS TIME KEEPING LATE TONIGHT DRY. THE NEXT SHIFTS WILL HAVE TO MONITOR THIS. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/... A WEAK UPPER TROF WILL MOVE THROUGH IN THE MORNING...THIS MAY CAUSE AN ISOLATED SHOWER OR SPRINKLE. THE BEST CHANCE WILL BE LATER IN THE AFTERNOON AND EVENING AS THE COLD FRONT MOVES IN. THE BEST CHANCE EXCEPT FOR NW OH WILL BE MAINLY AFTER MIDNIGHT AS MORE MOISTURE COMES IN. SHOWERS AND THUNDERSTORMS WILL BEGIN DECREASING FROM THE NORTH BY DAYBREAK AND THE DRYING SHOULD BE SOMEWHAT QUICK. THE PRECIPITABLE WATER WILL BE AROUND 2 INCHES FRIDAY NIGHT. SOME OF THE THUNDERSTORMS COULD BE STRONG WITH LOCALLY HEAVY RAIN. THE BEST THREAT OF SEVERE WOULD BE OVER NORTHWEST OHIO IN THE EVENING AND SEVERE WOULD BE ISOLATED AND VERY MARGINAL. THE LAKE AND 850 MB TEMPERATURE DIFFERENCE BY SUNDAY MORNING WILL BE NEAR 13C. SOME LAKE EFFECT CLOUDS WILL BE LIKELY. NOT EXPECTING ANY SHOWERS BECAUSE OF SO MUCH RIDGING. USED A BLEND OF GUIDANCE FOR THE TEMPERATURE FORECAST. && .LONG TERM /MONDAY THROUGH THURSDAY/... HIGH PRESSURE WILL BE LOCATED OVER NEW ENGLAND ON MONDAY...BUILDING OFFSHORE ON MONDAY NIGHT. SOUTHEASTERLY RETURN FLOW BEHIND THE DEPARTING HIGH WILL LEAD TO A GRADUAL INCREASE IN LOW LEVEL MOISTURE FROM THE SOUTHEAST. BY TUESDAY WE SEE THE FIRST IN A SERIES OF SHORTWAVES APPROACH THE OHIO VALLEY AND INTERACT WITH THIS MOISTURE TO CAUSE A CHANCE OF SHOWERS AND THUNDERSTORMS. LONG RANGE MODELS ARE STRUGGLING TO RESOLVE THESE SHORTWAVES AS WE TRANSITION FROM A MORE ZONAL UPPER LEVEL FLOW OVER THE WEEKEND TO A BROAD TROUGH THROUGH MIDWEEK. ADDED A CHANCE OF THUNDERSTORMS TO THE FORECAST ON TUESDAY AND WILL LEAVE POPS IN THROUGH MIDWEEK WITH THE UNSETTLED PATTERN SETTING UP. TEMPERATURES WILL BE TRICKY AND DEPEND ON COVERAGE OF CLOUDS AND SHOWERS. TEMPERATURES START THE LONG TERM OFF NEAR TO SLIGHTLY BELOW NORMAL...TRENDING COOLER TOWARDS DAY 7. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... SHOWERS ACROSS INDIANA CONTINUE TO WEAKEN AS THEY MOVE EAST INTO DRIER AIR. THE NEXT CHANCE FOR SHOWERS WILL NOT ARRIVE UNTIL LATE TONIGHT WHEN A FEW SHOWERS COULD TRICKLE SOUTH OUT OF MICHIGAN AS MOISTURE INCREASES AT TOL/FDY. CAN NOT ENTIRELY RULE OUT A THUNDERSTORM BUT CHANCES ARE LOW. OTHERWISE VFR CONDITIONS WILL CONTINUE UNTIL POSSIBLY LATE TONIGHT WHEN VISIBILITIES MAY DROP TO 4-6 MILES IN BR AS DEWPOINTS INCREASE BENEATH A SHALLOW INVERSION. INCLUDED THE RESTRICTED VISIBILITY AT MFD/CAK/YNG ALTHOUGH THIS MAY NOT OCCUR IF WINDS HOLD UP AROUND 5 KNOTS. SOUTHWEST WINDS WILL INCREASE THROUGH THE MORNING AND BE BREEZY AT TIMES WITH GUSTS OF 15-20 KNOTS ON FRIDAY AFTERNOON. CHANCES OF THUNDERSTORMS DEVELOP BETWEEN 18-00Z ON FRIDAY AFTERNOON BUT RAMP UP MORE AFTER 00Z FRIDAY NIGHT. OUTLOOK...NON VFR LIKELY IN SHOWERS AND THUNDERSTORMS FRIDAY NIGHT AND CONTINUING ON SATURDAY WITH SHOWERS ASSOCIATED WITH THE COLD FRONT. && .MARINE... WINDS WILL REMAIN OUT OF THE SOUTH OVERNIGHT WITH SOUTHWEST WINDS INCREASING TO 10 TO 15 KNOTS ON FRIDAY AHEAD OF AN APPROACHING COLD FRONT. THE FRONT WILL PUSH SOUTH ACROSS THE AREA ON FRIDAY NIGHT WITH WINDS SHIFTING TO THE NORTH BY EARLY SATURDAY. WAVES WILL INCREASE TO 2 TO 3 FEET WITH THE NORTHERLY FLOW ON SATURDAY. HIGH PRESSURE WILL BUILD EAST ACROSS THE GREAT LAKES FROM SATURDAY NIGHT THROUGH MONDAY WITH GENERALLY LIGHT WINDS AND WAVE CONDITIONS. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KIELTYKA NEAR TERM...KIELTYKA SHORT TERM...KIELTYKA LONG TERM...KEC AVIATION...KUBINA MARINE...KEC
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
347 PM EDT THU SEP 4 2014 .SYNOPSIS... A LOW WILL MOVE ACROSS ONTARIO TONIGHT AND INTO QUEBEC FRIDAY AND FRIDAY NIGHT. A COLD FRONT ASSOCIATED WITH THE LOW WILL MOVE ACROSS THE AREA FRIDAY NIGHT. A RIDGE WILL BUILD IN SATURDAY NIGHT AND LAST INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... THE CUMULUS WILL DISSIPATE QUICKLY. SOME MID AND HIGH CLOUDS WILL BE AROUND. PARTLY CLOUDY SHOULD HANDLE IT. WENT TOWARD THE WARMER GUIDANCE FOR LOWS BECAUSE OF THE DEW POINTS AND SOME WIND. THE HRRR MODEL TRIES TO BRING SOME SPRINKLES OR SHOWERS INTO NW OH BY EVENING...THIS IS THE REMNANTS OF THE SYSTEM FROM EARLIER. THIS AREA IS DECREASING...WILL KEEP IT DRY. THE NAM ESPECIALLY TRIES TO HINT AT SOME SHOWERS DEVELOPING OVER NORTHWEST OHIO TOWARD DAYBREAK FRIDAY. THE GFS KIND OF HINTS AT THAT TOO. AT THIS TIME KEEPING LATE TONIGHT DRY. THE NEXT SHIFTS WILL HAVE TO MONITOR THIS. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY NIGHT/... A WEAK UPPER TROF WILL MOVE THROUGH IN THE MORNING...THIS MAY CAUSE AN ISOLATED SHOWER OR SPRINKLE. THE BEST CHANCE WILL BE LATER IN THE AFTERNOON AND EVENING AS THE COLD FRONT MOVES IN. THE BEST CHANCE EXCEPT FOR NW OH WILL BE MAINLY AFTER MIDNIGHT AS MORE MOISTURE COMES IN. SHOWERS AND THUNDERSTORMS WILL BEGIN DECREASING FROM THE NORTH BY DAYBREAK AND THE DRYING SHOULD BE SOMEWHAT QUICK. THE PRECIPITABLE WATER WILL BE AROUND 2 INCHES FRIDAY NIGHT. SOME OF THE THUNDERSTORMS COULD BE STRONG WITH LOCALLY HEAVY RAIN. THE BEST THREAT OF SEVERE WOULD BE OVER NORTHWEST OHIO IN THE EVENING AND SEVERE WOULD BE ISOLATED AND VERY MARGINAL. THE LAKE AND 850 MB TEMPERATURE DIFFERENCE BY SUNDAY MORNING WILL BE NEAR 13C. SOME LAKE EFFECT CLOUDS WILL BE LIKELY. NOT EXPECTING ANY SHOWERS BECAUSE OF SO MUCH RIDGING. USED A BLEND OF GUIDANCE FOR THE TEMPERATURE FORECAST. && .LONG TERM /MONDAY THROUGH THURSDAY/... HIGH PRESSURE WILL BE LOCATED OVER NEW ENGLAND ON MONDAY...BUILDING OFFSHORE ON MONDAY NIGHT. SOUTHEASTERLY RETURN FLOW BEHIND THE DEPARTING HIGH WILL LEAD TO A GRADUAL INCREASE IN LOW LEVEL MOISTURE FROM THE SOUTHEAST. BY TUESDAY WE SEE THE FIRST IN A SERIES OF SHORTWAVES APPROACH THE OHIO VALLEY AND INTERACT WITH THIS MOISTURE TO CAUSE A CHANCE OF SHOWERS AND THUNDERSTORMS. LONG RANGE MODELS ARE STRUGGLING TO RESOLVE THESE SHORTWAVES AS WE TRANSITION FROM A MORE ZONAL UPPER LEVEL FLOW OVER THE WEEKEND TO A BROAD TROUGH THROUGH MIDWEEK. ADDED A CHANCE OF THUNDERSTORMS TO THE FORECAST ON TUESDAY AND WILL LEAVE POPS IN THROUGH MIDWEEK WITH THE UNSETTLED PATTERN SETTING UP. TEMPERATURES WILL BE TRICKY AND DEPEND ON COVERAGE OF CLOUDS AND SHOWERS. TEMPERATURES START THE LONG TERM OFF NEAR TO SLIGHTLY BELOW NORMAL...TRENDING COOLER TOWARDS DAY 7. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... SHOWERS ACROSS INDIANA CONTINUE TO WEAKEN AS THEY MOVE EAST INTO DRIER AIR. THE NEXT CHANCE FOR SHOWERS WILL NOT ARRIVE UNTIL LATE TONIGHT WHEN A FEW SHOWERS COULD TRICKLE SOUTH OUT OF MICHIGAN AS MOISTURE INCREASES AT TOL/FDY. CAN NOT ENTIRELY RULE OUT A THUNDERSTORM BUT CHANCES ARE LOW. OTHERWISE VFR CONDITIONS WILL CONTINUE UNTIL POSSIBLY LATE TONIGHT WHEN VISIBILITIES MAY DROP TO 4-6 MILES IN BR AS DEWPOINTS INCREASE BENEATH A SHALLOW INVERSION. INCLUDED THE RESTRICTED VISIBILITY AT MFD/CAK/YNG ALTHOUGH THIS MAY NOT OCCUR IF WINDS HOLD UP AROUND 5 KNOTS. SOUTHWEST WINDS WILL INCREASE THROUGH THE MORNING AND BE BREEZY AT TIMES WITH GUSTS OF 15-20 KNOTS ON FRIDAY AFTERNOON. CHANCES OF THUNDERSTORMS DEVELOP BETWEEN 18-00Z ON FRIDAY AFTERNOON BUT RAMP UP MORE AFTER 00Z FRIDAY NIGHT. OUTLOOK...NON VFR LIKELY IN SHOWERS AND THUNDERSTORMS FRIDAY NIGHT AND CONTINUING ON SATURDAY WITH SHOWERS ASSOCIATED WITH THE COLD FRONT. && .MARINE... WINDS WILL REMAIN OUT OF THE SOUTH OVERNIGHT WITH SOUTHWEST WINDS INCREASING TO 10 TO 15 KNOTS ON FRIDAY AHEAD OF AN APPROACHING COLD FRONT. THE FRONT WILL PUSH SOUTH ACROSS THE AREA ON FRIDAY NIGHT WITH WINDS SHIFTING TO THE NORTH BY EARLY SATURDAY. WAVES WILL INCREASE TO 2 TO 3 FEET WITH THE NORTHERLY FLOW ON SATURDAY. HIGH PRESSURE WILL BUILD EAST ACROSS THE GREAT LAKES FROM SATURDAY NIGHT THROUGH MONDAY WITH GENERALLY LIGHT WINDS AND WAVE CONDITIONS. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KIELTYKA NEAR TERM...KIELTYKA SHORT TERM...KIELTYKA LONG TERM...KEC AVIATION...KEC MARINE...KEC
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
326 PM EDT THU SEP 4 2014 .SYNOPSIS... WEAK HIGH PRESSURE SLIDES EAST WITH INCREASING MOISTURE THROUGH FRIDAY. COLD FRONT MOVES ACROSS SATURDAY AFTERNOON. FRONT SLOWS DOWN AS IT CREEPS SOUTH OF AREA. WEAK HIGH PRESSURE SUNDAY AFTERNOON. && .NEAR TERM /THROUGH FRIDAY/... INCREASED POPS TO LIKELY PER LATEST RADAR IMAGES SHOWING SCATTERED TO NUMEROUS SHOWERS WITH EMBEDDED THUNDERSTORMS AFFECTING THE WESTERN SLOPES AND PORTIONS OF THE SOUTHERN COAL FIELDS THIS AFTERNOON. THE STRONGER STORMS COULD PRODUCE 1 TO 2 INCHES PER HOUR. WILL CONTINUE MONITORING RADAR TRENDS LOOKING FOR REPETITIVE SHOWERS THAT COULD PRODUCE MINOR WATER PROBLEMS. RAINFALL ACTIVITY SHOULD DIMINISH IN INTENSITY AND COVERAGE LATER THIS EVENING. PREVIOUS DISCUSSION BELOW... HIGH PRESSURE...OFF TO THE EAST...HAS ALLOWED FOR WARM AND MUGGY WEATHER ACROSS THE REGION...WITH DEW POINTS ACROSS MUCH OF THE AREA THIS AFTERNOON IN THE MID 60S TO LOWER 70S. SATELLITE PW ESTIMATES AROUND 1.2 TO 1.4 INCHES ACROSS MUCH OF SOUTHWEST VA...WEST VA...AND EASTERN KY...WITH LOWER PWS OF AROUND AN INCH ACROSS SOUTHEAST OHIO. WITH THE LIGHT SOUTHERLY FLOW...AND THE HUMID UNSTABLE AIRMASS IN PLACE...HAVE STARTED TO SEE CONVECTION FIRE OFF...PARTICULARLY ACROSS WV/ERN KY/SW VA. MUCH OF THIS CONVECTION SHOULD DIE OFF AFTER SUNSET...BUT WITH THE LIGHT FLOW...AND HUMID AIRMASS IN PLACE...EXPECT LOCALIZED DOWNPOURS. 1 HOUR FFG AT THIS POINT IS GENERALLY 1.6 INCHES OR GREATER...SO NOT TOO CONCERNED ABOUT WATER ISSUES...BUT LOCALIZED ISSUES...PARTICULARLY IN LOW LYING SPOTS...CANNOT BE RULED OUT. MAINLY FOLLOWED THE HRRR MODEL FOR CONVECTION THIS AFTERNOON...AND INCREASED POPS FROM PREVIOUS FORECAST. MUCH OF THE ACTIVITY WILL WANE OVERNIGHT. COULD BE MORE FOG FORMATION THAN CURRENTLY FORECAST FOR TONIGHT. THIS WILL DEPEND ON HOW MUCH CLEARING IS ABLE TO OCCUR...AND LOCATIONS OF RAINFALL THIS AFTERNOON. A WEAK UPPER DISTURBANCE IS EXPECTED TO MOVE NORTHEAST THROUGH THE CWA TONIGHT AND ON FRIDAY...WHICH COULD HELP PROVIDE ENOUGH CLOUD COVER TO KEEP MUCH OF THE FOG FORMATION AT BAY. SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE AGAIN ON FRIDAY AS THE WEAK DISTURBANCE MOVES THROUGH THE REGION...COMBINED WITH DAYTIME HEATING. COLD FRONT WILL BEGIN TO APPROACH THE AREA TOWARDS THE END OF THE PERIOD...GENERALLY ACROSS NW OHIO/NORTHERN IN BY END OF PERIOD. DUE TO THE TIMING OF THE FRONT...SEVERE IS NOT EXPECTED ON FRIDAY...BUT HEAVY DOWNPOURS WILL CONTINUE TO BE POSSIBLE. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... WE SEEM TO BE BOTTOM FEEDERS LATELY. LIFE AT THE BOTTOM OF THE WESTERLIES CONTINUES DURING THIS TIME FRAME...WITH ANOTHER FRONT TRYING TO SINK SOUTH SATURDAY...BUT THEN STRUGGLING TO MOVE SOUTH OF OUR FORECAST AREA SATURDAY NIGHT INTO SUNDAY MORNING. NO MAJOR CHANGES TO THE MAIN "BISCUIT" ON SATURDAY INTO SATURDAY EVENING. BACK TO FRIDAY NIGHT. STILL WANT TO KEEP MOST OF THE LOWLANDS DRY FOR THE EVENING HOURS. HAD THE 20 AND 30 POPS FROM THE AFTERNOON WANING OVER THE MOUNTAIN COUNTIES 00Z TO 03Z. HAVE CHANCE POPS INCREASING 04Z TO 10Z SATURDAY IN SOUTHEAST OHIO...AHEAD OF THE NEXT FRONT AND APPROACHING MID LEVEL DISTURBANCES IN THE BASE OF THE WESTERLY FLOW IN THE MIDWEST. STILL HAVE OUR LIKELY POPS MOVING SE ACROSS CWA DURING THE 12Z SATURDAY TO 00Z SUNDAY TIME FRAME. COULD EASILY SEE BAND OF CONVECTION WELL AHEAD OF THE FRONT...THEN A SMALLER BAND NEAR THE FRONT LATER SATURDAY AFTERNOON INTO SATURDAY EVENING. COULD EASILY SEE 2000+ J/KG CAPE DEVELOP ESPECIALLY CKB-HTS ON E AND SE BY AFTERNOON. YET...STEERING WIND FLOW FROM 12Z MODELS ABOUT 25 TO 30 KNOTS...NOT TOO FAST...NOT TOO SLOW. DID TRY TO INCREASE MAX TEMPERATURE A BIT FROM EKN-CRW ON SE ON SATURDAY...FIGURING THE HIGHER POPS DO NOT ARRIVE UNTIL THE AFTERNOON HOURS. ALSO TRIED TO HAVE THAT MAXIMUM TEMPERATURE AROUND MIDDAY SATURDAY WITH TEMPERATURES MODIFIED BY CONVECTION DURING THE MID AND LATE AFTERNOON. THIS FRONT EXPECTED TO CREEP THROUGH...BUT LOW LEVEL WINDS AGAIN VEER QUICKLY FROM NORTH TO EAST...RESULTING IN HOLDING UP THE DRYING IN SOUTHERN WEST VIRGINIA AND SOUTHWEST VIRGINIA ON SUNDAY. MAIN DRYING IN THE NORTH AND WESTERN COUNTIES. DIFFICULT TO FIGURE WHEN...OR IF...THE CLOUDS IN THE SOUTH WILL BREAK SUNDAY AFTERNOON. SO KEPT MAXIMUM TEMPERATURES DOWN ACROSS THE SOUTHERN WV COAL FIELDS. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... USED WPC THINKING WITH SOME TWEAKS. WEAK SURFACE HIGH PRESSURE WILL BE IN CONTROL ACROSS THE REGION SUNDAY NIGHT INTO MONDAY NIGHT. A WARM FRONT WILL THEN LIFT NORTH TUESDAY...WITH A COLD FRONT PUSHING EAST ON THURSDAY. WPC TEMPS LOOKED GOOD AND WERE GENERALLY USED. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... 18Z THURSDAY THRU 18Z FRIDAY... SCATTERED CONVECTION THROUGH 00-02Z FRIDAY. EXPECT BRIEF MVFR CONDITIONS IN VICINITY OF STORMS. EXPECT PATCHY IFR FOG TO DEVELOP AGAIN TONIGHT...PARTICULARLY AFTER 06Z...IN AREAS WHERE CLEARING IS ABLE TO TAKE PLACE...AND WHERE PRECIPITATION OCCURS THURSDAY AFTERNOON. ANY FOG WILL LIFT AFTER 13Z FOR A RETURN OF VFR CONDITIONS AREA WIDE. CONVECTION WILL REFIRE ACROSS AREA...PARTICULARLY WV/SOUTHWEST VA/ERN KY AGAIN AFTER 16Z FRIDAY. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING OF CONVECTION MAY VARY FROM FORECAST. EXTENT AND DEPTH OF FOG FORMATION TONIGHT MAY VARY FROM FORECAST. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 20 21 22 23 00 01 02 03 04 05 06 07 EDT 1HRLY 16 17 18 19 20 21 22 23 00 01 02 03 CRW CONSISTENCY H H H H H H H H H M M H HTS CONSISTENCY H H H H H H H H H M M M BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H M M H CKB CONSISTENCY H H H H H H H H H M M M AFTER 18Z FRIDAY... IFR POSSIBLE IN SHOWERS AND THUNDERSTORMS SATURDAY. IFR FOG POSSIBLE SUNDAY MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JSH/KTB/SL NEAR TERM...ARJ/SL SHORT TERM...KTB LONG TERM...JSH AVIATION...SL
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
315 PM EDT THU SEP 4 2014 .SYNOPSIS... WEAK HIGH PRESSURE SLIDES EAST WITH INCREASING MOISTURE THROUGH FRIDAY. COLD FRONT MOVES ACROSS SATURDAY AFTERNOON. FRONT SLOWS DOWN AS IT CREEPS SOUTH OF AREA. WEAK HIGH PRESSURE SUNDAY AFTERNOON. && .NEAR TERM /THROUGH FRIDAY/... HIGH PRESSURE...OFF TO THE EAST...HAS ALLOWED FOR WARM AND MUGGY WEATHER ACROSS THE REGION...WITH DEW POINTS ACROSS MUCH OF THE AREA THIS AFTERNOON IN THE MID 60S TO LOWER 70S. SATELLITE PW ESTIMATES AROUND 1.2 TO 1.4 INCHES ACROSS MUCH OF SOUTHWEST VA...WEST VA...AND EASTERN KY...WITH LOWER PWS OF AROUND AN INCH ACROSS SOUTHEAST OHIO. WITH THE LIGHT SOUTHERLY FLOW...AND THE HUMID UNSTABLE AIRMASS IN PLACE...HAVE STARTED TO SEE CONVECTION FIRE OFF...PARTICULARLY ACROSS WV/ERN KY/SW VA. MUCH OF THIS CONVECTION SHOULD DIE OFF AFTER SUNSET...BUT WITH THE LIGHT FLOW...AND HUMID AIRMASS IN PLACE...EXPECT LOCALIZED DOWNPOURS. 1 HOUR FFG AT THIS POINT IS GENERALLY 1.6 INCHES OR GREATER...SO NOT TOO CONCERNED ABOUT WATER ISSUES...BUT LOCALIZED ISSUES...PARTICULARLY IN LOW LYING SPOTS...CANNOT BE RULED OUT. MAINLY FOLLOWED THE HRRR MODEL FOR CONVECTION THIS AFTERNOON...AND INCREASED POPS FROM PREVIOUS FORECAST. MUCH OF THE ACTIVITY WILL WANE OVERNIGHT. COULD BE MORE FOG FORMATION THAN CURRENTLY FORECAST FOR TONIGHT. THIS WILL DEPEND ON HOW MUCH CLEARING IS ABLE TO OCCUR...AND LOCATIONS OF RAINFALL THIS AFTERNOON. A WEAK UPPER DISTURBANCE IS EXPECTED TO MOVE NORTHEAST THROUGH THE CWA TONIGHT AND ON FRIDAY...WHICH COULD HELP PROVIDE ENOUGH CLOUD COVER TO KEEP MUCH OF THE FOG FORMATION AT BAY. SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE AGAIN ON FRIDAY AS THE WEAK DISTURBANCE MOVES THROUGH THE REGION...COMBINED WITH DAYTIME HEATING. COLD FRONT WILL BEGIN TO APPROACH THE AREA TOWARDS THE END OF THE PERIOD...GENERALLY ACROSS NW OHIO/NORTHERN IN BY END OF PERIOD. DUE TO THE TIMING OF THE FRONT...SEVERE IS NOT EXPECTED ON FRIDAY...BUT HEAVY DOWNPOURS WILL CONTINUE TO BE POSSIBLE. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... WE SEEM TO BE BOTTOM FEEDERS LATELY. LIFE AT THE BOTTOM OF THE WESTERLIES CONTINUES DURING THIS TIME FRAME...WITH ANOTHER FRONT TRYING TO SINK SOUTH SATURDAY...BUT THEN STRUGGLING TO MOVE SOUTH OF OUR FORECAST AREA SATURDAY NIGHT INTO SUNDAY MORNING. NO MAJOR CHANGES TO THE MAIN "BISCUIT" ON SATURDAY INTO SATURDAY EVENING. BACK TO FRIDAY NIGHT. STILL WANT TO KEEP MOST OF THE LOWLANDS DRY FOR THE EVENING HOURS. HAD THE 20 AND 30 POPS FROM THE AFTERNOON WANING OVER THE MOUNTAIN COUNTIES 00Z TO 03Z. HAVE CHANCE POPS INCREASING 04Z TO 10Z SATURDAY IN SOUTHEAST OHIO...AHEAD OF THE NEXT FRONT AND APPROACHING MID LEVEL DISTURBANCES IN THE BASE OF THE WESTERLY FLOW IN THE MIDWEST. STILL HAVE OUR LIKELY POPS MOVING SE ACROSS CWA DURING THE 12Z SATURDAY TO 00Z SUNDAY TIME FRAME. COULD EASILY SEE BAND OF CONVECTION WELL AHEAD OF THE FRONT...THEN A SMALLER BAND NEAR THE FRONT LATER SATURDAY AFTERNOON INTO SATURDAY EVENING. COULD EASILY SEE 2000+ J/KG CAPE DEVELOP ESPECIALLY CKB-HTS ON E AND SE BY AFTERNOON. YET...STEERING WIND FLOW FROM 12Z MODELS ABOUT 25 TO 30 KNOTS...NOT TOO FAST...NOT TOO SLOW. DID TRY TO INCREASE MAX TEMPERATURE A BIT FROM EKN-CRW ON SE ON SATURDAY...FIGURING THE HIGHER POPS DO NOT ARRIVE UNTIL THE AFTERNOON HOURS. ALSO TRIED TO HAVE THAT MAXIMUM TEMPERATURE AROUND MIDDAY SATURDAY WITH TEMPERATURES MODIFIED BY CONVECTION DURING THE MID AND LATE AFTERNOON. THIS FRONT EXPECTED TO CREEP THROUGH...BUT LOW LEVEL WINDS AGAIN VEER QUICKLY FROM NORTH TO EAST...RESULTING IN HOLDING UP THE DRYING IN SOUTHERN WEST VIRGINIA AND SOUTHWEST VIRGINIA ON SUNDAY. MAIN DRYING IN THE NORTH AND WESTERN COUNTIES. DIFFICULT TO FIGURE WHEN...OR IF...THE CLOUDS IN THE SOUTH WILL BREAK SUNDAY AFTERNOON. SO KEPT MAXIMUM TEMPERATURES DOWN ACROSS THE SOUTHERN WV COAL FIELDS. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... USED WPC THINKING WITH SOME TWEAKS. WEAK SURFACE HIGH PRESSURE WILL BE IN CONTROL ACROSS THE REGION SUNDAY NIGHT INTO MONDAY NIGHT. A WARM FRONT WILL THEN LIFT NORTH TUESDAY...WITH A COLD FRONT PUSHING EAST ON THURSDAY. WPC TEMPS LOOKED GOOD AND WERE GENERALLY USED. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... 18Z THURSDAY THRU 18Z FRIDAY... SCATTERED CONVECTION THROUGH 00-02Z FRIDAY. EXPECT BRIEF MVFR CONDITIONS IN VICINITY OF STORMS. EXPECT PATCHY IFR FOG TO DEVELOP AGAIN TONIGHT...PARTICULARLY AFTER 06Z...IN AREAS WHERE CLEARING IS ABLE TO TAKE PLACE...AND WHERE PRECIPITATION OCCURS THURSDAY AFTERNOON. ANY FOG WILL LIFT AFTER 13Z FOR A RETURN OF VFR CONDITIONS AREA WIDE. CONVECTION WILL REFIRE ACROSS AREA...PARTICULARLY WV/SOUTHWEST VA/ERN KY AGAIN AFTER 16Z FRIDAY. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z FRIDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING OF CONVECTION MAY VARY FROM FORECAST. EXTENT AND DEPTH OF FOG FORMATION TONIGHT MAY VARY FROM FORECAST. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05 EDT 1HRLY 14 15 16 17 18 19 20 21 22 23 00 01 CRW CONSISTENCY H H H H H H H H H H H M HTS CONSISTENCY H H H H H H H H H H H M BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H H H H H H H H H H H PKB CONSISTENCY H H H H H H H H H H H M CKB CONSISTENCY H H H H H H H H H H H M AFTER 18Z FRIDAY... IFR POSSIBLE IN SHOWERS AND THUNDERSTORMS SATURDAY. IFR FOG POSSIBLE SUNDAY MORNING. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JSH/KTB/SL NEAR TERM...SL SHORT TERM...KTB LONG TERM...JSH AVIATION...SL
AREA FORECAST DISCUSSION
NWS TULSA OK
1156 PM CDT WED SEP 3 2014 .AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM. VFR CONDITIONS ARE EXPECTED THROUGH THE ENTIRE TAF PERIOD AT ALL SITES. && .PREV DISCUSSION... /ISSUED 844 PM CDT WED SEP 3 2014/ DISCUSSION... HEAT INDICES HAVE IMPROVED AND THE WINDS HAVE BACKED OFF AS MIXING CEASES WITH THE SETTING OF THE GIANT ENERGY BALL. A LEE TROUGH OVER THE HIGH PLAINS WILL KEEP SOME SOUTH WIND GOING ALL NIGHT...ESPECIALLY AT TUL...SO LOWS WILL BE MILD ACROSS ERN OK AND W CNTRL AR WHERE TERRAIN EFFECTS HELP TO MAINTAIN AN EAST WIND. RIDGING ALOFT WILL MAINTAIN DRY CONDITIONS UNTIL A FRONT ARRIVES LATE FRIDAY. LACY PREV DISCUSSION... /ISSUED 604 PM CDT WED SEP 3 2014/ AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM. VFR CONDITIONS ARE EXPECTED THROUGH THE ENTIRE TAF PERIOD AT ALL SITES. PREV DISCUSSION... /ISSUED 353 PM CDT WED SEP 3 2014/ DISCUSSION... WARM TEMPERATURES AND BREEZY SOUTHERLY WINDS WERE COMMON ACROSS EASTERN OKLAHOMA AND NORTHWEST ARKANSAS THIS AFTERNOON AS HIGH PRESSURE CONTINUED TO HOLD OVER THE SOUTHERN PLAINS. SOME SCATTERED CONVECTION HAD DEVELOPED OVER FAR SOUTHEAST KANSAS LATE THIS AFTERNOON...AND THE LATEST HRRR TRIES TO DEVELOP THIS PRECIP AND PUSH IT SOUTHEAST INTO NORTHWEST/NORTH CENTRAL OKLAHOMA THIS EVENING AND OVERNIGHT. WILL KEEP POPS BELOW MENTIONABLE CRITERIA FOR NOW AS MOST OF THIS ACTIVITY SHOULD REMAIN NORTHWEST OF THE CWA. EVENING SHIFT WILL NEED TO MONITOR FOR ANY CHANGING CONDITIONS. HOT TEMPERATURES AND BREEZY SOUTH SOUTHWESTERLY WINDS WILL CONTINUE ACROSS THE CWA THURSDAY BEFORE A COLD FRONT IS EXPECTED TO MOVE INTO THE REGION FRIDAY. A WAVE MOVING EASTWARD ALONG THE U.S./CANADA BORDER WILL PUSH A TRAILING COLD FRONT SOUTHEASTWARD THROUGH THE PLAINS AND INTO THE CWA DURING THE DAY FRIDAY. CHANCES FOR SHOWERS AND THUNDERSTORMS BECOME POSSIBLE FRIDAY MORNING AS THE FRONT NEARS THE REGION AND SHOULD INCREASE IN COVERAGE FRIDAY AFTERNOON/EVENING WHILE THE FRONT PUSHES INTO THE CWA. CONDITIONS AHEAD OF THE FRONT AND PRECIP SHOULD CONTINUE TO BE WARM WITH SOUTHWESTERLY WINDS. THE FRONTAL BOUNDARY IS FORECAST TO MOVE THROUGH THE REGION FRIDAY NIGHT AND SATURDAY WITH CONTINUED CHANCES FOR SHOWERS AND THUNDERSTORMS. POST FRONTAL PRECIP WILL BE POSSIBLE SATURDAY NIGHT INTO SUNDAY BEFORE THE UPPER LEVEL TROF AXIS ASSOCIATED WITH THE WAVE OVER SOUTHERN CANADA MOVES OUT OF THE PLAINS. IN THE WAKE OF THE EXITING TROF...COOLER TEMPS AND NORTHERLY WINDS ARE EXPECTED ACROSS THE REGION INTO THE START OF THE NEXT WORK WEEK. SOUTHERLY WINDS QUICKLY RETURN WITH WARMER TEMPERATURES AGAIN FOR THE MIDDLE PART OF NEXT WEEK AHEAD OF A LONGWAVE TROF FORECAST TO MOVE OUT OF SOUTHERN CANADA INTO THE PLAINS. LATEST GFS AND ECMWF DISAGREE ON TIMING OF THIS NEXT WAVE AND ASSOCIATED COLD FRONT INTO THE CWA. THE ECMWF IS ABOUT 12-24 HRS FASTER COMPARED TO THE GFS. WILL USE A BLENDED MODEL SOLUTION ALONG WITH PREVIOUS FORECAST...PUSHING THE FRONT THROUGH WEDNESDAY NIGHT AND THURSDAY. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL AGAIN BECOME POSSIBLE MID WEEK AND CONTINUE INTO THE SECOND HALF OF NEXT WEEK AS THE FRONT MOVES THROUGH. COOLER TEMPS WILL AGAIN BE POSSIBLE LATE NEXT WEEK. && .TSA WATCHES/WARNINGS/ADVISORIES... OK...NONE. AR...NONE. && $$ AVIATION...23
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1140 PM EDT FRI SEP 5 2014 .SYNOPSIS... A COLD FRONT WILL PUSH SOUTHEAST ACROSS THE STATE ON SATURDAY. HIGH PRESSURE OVER THE MIDWEST WILL THEN SLIDE ACROSS PENNSYLVANIA SUNDAY INTO EARLY NEXT WEEK...ACCOMPANIED BY A REFRESHINGLY COOLER AND DRIER AIRMASS. && .NEAR TERM /UNTIL 7 AM SATURDAY MORNING/... 1030PM UPDATE... NEWEST NAM/RAP/HRRR ALL POINT TO AN ISOLD SHRA POPPING UP LATER TONIGHT IN THE SE. WHILE SKEPTICAL OF THIS...THERE DOES APPEAR TO BE A VERY WEAK SHORT WAVE MOVING THRU PA FROM W-E FROM 06-12Z. NO LLVL INFLOW BUT AMBIENT MOISTURE IS HIGH AND RAP KEEPS 700-1000 JOULES OF CAPE THERE ALL NIGHT AND INTO THE MORNING. WILL THEREFORE ADD SOME POPS IN THE SE FOR LATE TONIGHT. THE WAVE PUSHES EAST BY 12Z. THE BIGGER CONCERN IS THE ELEPHANT OVER LAKE ERIE...BUT OUTFLOWS SEEM TO BE VISIBLE ON CLE/BUF RADARS PUSHING SOUTHWARD. THIS SHOULD SERVE TO DIMINISH THE STORMS A BIT AS THEY MOVE INTO THE CWA. WILL HOLD ALL POPS THE SAME IN THE NW. ADDED PATCHY FOG IN MORE SPOTS AS WELL - MAINLY WHERE IT RAINED. 645 PM UPDATE... PULSE STORMS HAVE PUTTERED OUT AS THE SUN NOW SINKS EARLIER AS WE MOVE DEEPER INTO SEPTEMBER. EXPECT TO HAVE TO WAIT UNTIL THE SHOWERS/STORMS OVER MI/LH MOVE INTO THE NORTHWEST OVERNIGHT FOR ANY MORE PRECIP. LITTLE AIR MOVEMENT. HIGH AMBIENT MOISTURE WILL LIKELY CONTRIBUTE TO FOG TONIGHT...ESP IN THE S/SE WHERE IT RAINED HEAVILY. PREV... REGIONAL VIS AND RADAR LOOP SHOWS A QUICK TRANSITION TO ISOLATED SHOWERS AND A FEW PULSE TSRA IN THE UNSEASONABLY WARM AND VERY HUMID AIRMASS ACROSS CENTRAL PENN. TERRAIN FEATURES ARE PLAYING A DOMINANT ROLE IN THE LOCATION AND SLOW EASTWARD MOVEMENT OF THE CONVECTION. WE SHOULD SEE THE SHOWERS AND TSRA QUICKLY DISSIPATE EARLY THIS EVENING...BUT COULD DRIFT UP TO A FEW TENS OF MILES EAST OF THEIR TRIGGER POINTS BEFORE FALLING APART COMPLETELY BY 01Z. THESE SLOW MOVING...AND VERY EFFICIENT RAIN-MAKERS WILL LEAD TO SOME LOCALLY AND GENERALLY BRIEF TORRENTIAL RAINS. HOWEVER...MOST LOCATIONS SHOULDN/T SEE A DROP OF RAIN THROUGH 08Z SATURDAY BEFORE THE LEADING EDGE OF 40-45MM PWAT AIR AND STRONGER LOW TO MID LEVEL FLOW AHEAD OF A COLD FRONT ENTERS THE REGION FROM THE OHIO VALLEY. SKIES FOR MUCH OF THE OVERNIGHT SHOULD BE PARTLY CLOUDY /MAINLY PATCHY STRATO CU AND SOME ALTO CU/. IT WILL BE VERY MUGGY ONCE AGAIN /ESPECIALLY FOR EARLY SEPT/ WITH LOW TEMPS IN THE 60S...TO AROUND 70F IN THE SE. PATCHY FOG WILL FORM FOR A FEW HOUR AROUND DAYBREAK /ESPECIALLY ACROSS THE SOUTH AND EAST. && .SHORT TERM /7 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... MDL TIMING OF COLD FRONT CONTINUES TO SUGGEST SHRA/TSRA WILL MOVE INTO THE NW MTNS ARND OR SHORTLY AFTER DAWN SATURDAY. LATEST 12Z MODELS SHOW LITTLE REASON TO MODIFY THE ALREADY HIGH POPS PAINTED IN OUR GRIDDED DATABASE /AROUND 80 PERCENT/ FOR SHOWERS AND SCTD TSRA ALONG AND AHEAD OF THE CFRONT SATURDAY. SREF AND GEFS PWATS ARE BTWN 1-2SD ABV NORMAL IN ADVANCE OF CDFRONT. 09Z/12Z ENSEMBLES GUIDANCE SUPPORT CATEGORICAL POPS ACROSS MOST OF CENTRAL PA. MORNING SHOWERS ACROSS THE NW MTNS SHOULD PUSH SE AND TRANSITION/GROW INTO NUMEROUS +SHRA AND A FEW BKN LINES OF TSRA IN THE AFTERNOON OVR THE SERN HALF OR SO OF THE FCST AREA...WHERE EARLY HEATING WILL RESULT IN A MODERATELY UNSTABLE PRE-FRONTAL AIR MASS BY AFTN. SREF PROB FOR CAPES EXCEEDING 2000 J/KG RAMP UP QUICKLY IN THE 15-18Z TIMEFRAME ALONG AND EAST OF A LINE FROM NEAR KJST...TO KUNV AND KELM. HOWEVER...FAIRLY MODEST MID LVL WINDS AND DEEP LYR SHEAR POINT TOWARD A LIMITED SVR WX THREAT. BEST CHC APPEARS TO BE ACROSS THE LOWER SUSQ VALLEY DURING THE MID AFTERNOON TO EARLY EVENING. LOCALLY HEAVY RAINS OF AN INCH OR SO IN UNDER ONE HOUR MAY BE AN EQUALLY IMPORTANT IMPACT FROM THE CFROPA AND ACCOMPANYING TSRA. MAX TEMPS SAT AFTERNOON WILL VARY FROM JUST THE L70S ACROSS THE NW...TO THE U80S IN THE SE ZONES. PARTIAL LATE NIGHT CLEARING SATURDAY NIGHT /WITH WET GROUND AND STILL MODERATE DEWPOINTS IN THE 50S TO NEAR 60F/ WILL LEAD TO LOCALLY DENSE VALLEY FOG AFTER 06Z SUNDAY THROUGH 13Z SUNDAY UNDER LIGHT NW TO NRLY SFC FLOW. && .LONG TERM /SUNDAY THROUGH FRIDAY/... *COOLER/DRY WEATHER SUNDAY INTO MONDAY *NEAR AVERAGE TEMPERATURES AND MORE UNSETTLED CONDITIONS TUE-THU THE REGIONAL PATTERN ALOFT WILL FEATURE INCREASING TROUGHINESS THROUGH THE MEDIUM RANGE PERIOD...WITH THE GLOBAL ENSEMBLE MEANS SHOWING A CORE OF NEGATIVE HEIGHT ANOMALIES OVER THE UPPER MIDWEST AND GREAT LAKES REGIONS BY THE MIDDLE TO LATER PART OF NEXT WEEK /SEPT 11-12TH/. OVERALL...THE NAEFS/GEFS AND ECENS ALL SIGNAL A TRANSITION TOWARD A HIGHER AMPLITUDE PATTERN PARTICULARLY ACROSS SOUTH CENTRAL CANADA. AN ELONGATED COLD FRONT TRAILING A RELATIVELY STRONG SFC LOW OVER NEWFOUNDLAND/LABRADOR WILL BE PASSING SOUTH OF PA SAT NIGHT. A MODIFIED CANADIAN HIGH BUILDING SWD INTO THE CENTRAL PLAINS WILL EVENTUALLY SHIFT EWD THROUGH THE NORTHEAST STATES AND MOVE INTO THE MARITIMES BY NEXT WED. SHRA/TSRA WILL END FROM NW-SE SAT NGT WITH MUCH DRIER AIR FILTERING IN FOR SUNDAY. DRY WX SHOULD CONTINUE INTO EARLY NEXT WEEK BEFORE CONDS TURN MORE UNSETTLED. EASTERLY WINDS TO THE SOUTH OF HP CELL MOVG INTO THE MARITIMES ARE SUGGESTIVE OF A COOL-AIR WEDGE OVER THE MID-ATLC WHICH SHOULD DAYTIME HIGHS NEAR AVG. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... SKIES ARE CLEARING AND AS THE INVERSION STRENGTHENS THE WINDS WILL BECOME LIGHT TO CALM. HIGH DEWPOINTS REMAIN IN PLACE TONIGHT AHEAD OF AN APPROACHING COLD FRONT. THIS WILL LEAD TO REDEVELOPMENT OF FOG/HAZE...AND AN ENCROACHING MVFR CLOUD DECK ALONG WITH A CHANCE FOR SHOWERS AFTER 06Z IN THE NW. AREAS OF LIFR ARE POSSIBLE ACROSS THE EASTERN TWO THIRDS OF THE STATE...WITH VLIFR POSSIBLE ACROSS SOME PORTIONS OF THE SUSQ VALLEY BETWEEN 09-13Z SATURDAY. THE BIGGEST FORECAST QUESTION AND CONCERN WILL BE THE TIMING OF THE APPROACHING FRONT AND ITS IMPACTS. EXPECT NUMEROUS SHOWERS AND TSRA WITH OCNL RESTRICTIONS TO OCCUR SATURDAY...MAINLY AFTER 15Z THROUGH THE SOUTHWESTERN AND CENTRAL TAF SITES AND AFTER 18Z ACROSS THE SE...LOWER SUSQ VALLEY AIRFIELDS SUCH AS KMDT...KCXY...KLNS AND KTHV. IN THE WAKE OF THE FRONT...CLEARING SKIES AND TRAPPED MOISTURE COULD ALLOW FOR REDUCING CIGS/VSBYS SATURDAY NIGHT INTO SUNDAY MORNING. OUTLOOK... SUN...AM FOG POSS NW MTNS. MON...PATCHY AM VALLEY FOG POSS. TUE...CHC SHOWERS/TSTMS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...DANGELO/LAMBERT SHORT TERM...FITZGERALD/LAMBERT LONG TERM...FITZGERALD/GARTNER AVIATION...LAMBERT/CERU
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1043 PM EDT FRI SEP 5 2014 .SYNOPSIS... A COLD FRONT WILL PUSH SOUTHEAST ACROSS THE STATE ON SATURDAY. HIGH PRESSURE OVER THE MIDWEST WILL THEN SLIDE ACROSS PENNSYLVANIA SUNDAY INTO EARLY NEXT WEEK...ACCOMPANIED BY A REFRESHINGLY COOLER AND DRIER AIRMASS. && .NEAR TERM /UNTIL 7 AM SATURDAY MORNING/... 1030PM UPDATE... NEWEST NAM/RAP/HRRR ALL POINT TO AN ISOLD SHRA POPPING UP LATER TONIGHT IN THE SE. WHILE SKEPTICAL OF THIS...THERE DOES APPEAR TO BE A VERY WEAK SHORT WAVE MOVING THRU PA FROM W-E FROM 06-12Z. NO LLVL INFLOW BUT AMBIENT MOISTURE IS HIGH AND RAP KEEPS 700-1000 JOULES OF CAPE THERE ALL NIGHT AND INTO THE MORNING. WILL THEREFORE ADD SOME POPS IN THE SE FOR LATE TONIGHT. THE WAVE PUSHES EAST BY 12Z. THE BIGGER CONCERN IS THE ELEPHANT OVER LAKE ERIE...BUT OUTFLOWS SEEM TO BE VISIBLE ON CLE/BUF RADARS PUSHING SOUTHWARD. THIS SHOULD SERVE TO DIMINISH THE STORMS A BIT AS THEY MOVE INTO THE CWA. WILL HOLD ALL POPS THE SAME IN THE NW. ADDED PATCHY FOG IN MORE SPOTS AS WELL - MAINLY WHERE IT RAINED. 645 PM UPDATE... PULSE STORMS HAVE PUTTERED OUT AS THE SUN NOW SINKS EARLIER AS WE MOVE DEEPER INTO SEPTEMBER. EXPECT TO HAVE TO WAIT UNTIL THE SHOWERS/STORMS OVER MI/LH MOVE INTO THE NORTHWEST OVERNIGHT FOR ANY MORE PRECIP. LITTLE AIR MOVEMENT. HIGH AMBIENT MOISTURE WILL LIKELY CONTRIBUTE TO FOG TONIGHT...ESP IN THE S/SE WHERE IT RAINED HEAVILY. PREV... REGIONAL VIS AND RADAR LOOP SHOWS A QUICK TRANSITION TO ISOLATED SHOWERS AND A FEW PULSE TSRA IN THE UNSEASONABLY WARM AND VERY HUMID AIRMASS ACROSS CENTRAL PENN. TERRAIN FEATURES ARE PLAYING A DOMINANT ROLE IN THE LOCATION AND SLOW EASTWARD MOVEMENT OF THE CONVECTION. WE SHOULD SEE THE SHOWERS AND TSRA QUICKLY DISSIPATE EARLY THIS EVENING...BUT COULD DRIFT UP TO A FEW TENS OF MILES EAST OF THEIR TRIGGER POINTS BEFORE FALLING APART COMPLETELY BY 01Z. THESE SLOW MOVING...AND VERY EFFICIENT RAIN-MAKERS WILL LEAD TO SOME LOCALLY AND GENERALLY BRIEF TORRENTIAL RAINS. HOWEVER...MOST LOCATIONS SHOULDN/T SEE A DROP OF RAIN THROUGH 08Z SATURDAY BEFORE THE LEADING EDGE OF 40-45MM PWAT AIR AND STRONGER LOW TO MID LEVEL FLOW AHEAD OF A COLD FRONT ENTERS THE REGION FROM THE OHIO VALLEY. SKIES FOR MUCH OF THE OVERNIGHT SHOULD BE PARTLY CLOUDY /MAINLY PATCHY STRATO CU AND SOME ALTO CU/. IT WILL BE VERY MUGGY ONCE AGAIN /ESPECIALLY FOR EARLY SEPT/ WITH LOW TEMPS IN THE 60S...TO AROUND 70F IN THE SE. PATCHY FOG WILL FORM FOR A FEW HOUR AROUND DAYBREAK /ESPECIALLY ACROSS THE SOUTH AND EAST. && .SHORT TERM /7 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... MDL TIMING OF COLD FRONT CONTINUES TO SUGGEST SHRA/TSRA WILL MOVE INTO THE NW MTNS ARND OR SHORTLY AFTER DAWN SATURDAY. LATEST 12Z MODELS SHOW LITTLE REASON TO MODIFY THE ALREADY HIGH POPS PAINTED IN OUR GRIDDED DATABASE /AROUND 80 PERCENT/ FOR SHOWERS AND SCTD TSRA ALONG AND AHEAD OF THE CFRONT SATURDAY. SREF AND GEFS PWATS ARE BTWN 1-2SD ABV NORMAL IN ADVANCE OF CDFRONT. 09Z/12Z ENSEMBLES GUIDANCE SUPPORT CATEGORICAL POPS ACROSS MOST OF CENTRAL PA. MORNING SHOWERS ACROSS THE NW MTNS SHOULD PUSH SE AND TRANSITION/GROW INTO NUMEROUS +SHRA AND A FEW BKN LINES OF TSRA IN THE AFTERNOON OVR THE SERN HALF OR SO OF THE FCST AREA...WHERE EARLY HEATING WILL RESULT IN A MODERATELY UNSTABLE PRE-FRONTAL AIR MASS BY AFTN. SREF PROB FOR CAPES EXCEEDING 2000 J/KG RAMP UP QUICKLY IN THE 15-18Z TIMEFRAME ALONG AND EAST OF A LINE FROM NEAR KJST...TO KUNV AND KELM. HOWEVER...FAIRLY MODEST MID LVL WINDS AND DEEP LYR SHEAR POINT TOWARD A LIMITED SVR WX THREAT. BEST CHC APPEARS TO BE ACROSS THE LOWER SUSQ VALLEY DURING THE MID AFTERNOON TO EARLY EVENING. LOCALLY HEAVY RAINS OF AN INCH OR SO IN UNDER ONE HOUR MAY BE AN EQUALLY IMPORTANT IMPACT FROM THE CFROPA AND ACCOMPANYING TSRA. MAX TEMPS SAT AFTERNOON WILL VARY FROM JUST THE L70S ACROSS THE NW...TO THE U80S IN THE SE ZONES. PARTIAL LATE NIGHT CLEARING SATURDAY NIGHT /WITH WET GROUND AND STILL MODERATE DEWPOINTS IN THE 50S TO NEAR 60F/ WILL LEAD TO LOCALLY DENSE VALLEY FOG AFTER 06Z SUNDAY THROUGH 13Z SUNDAY UNDER LIGHT NW TO NRLY SFC FLOW. && .LONG TERM /SUNDAY THROUGH FRIDAY/... *COOLER/DRY WEATHER SUNDAY INTO MONDAY *NEAR AVERAGE TEMPERATURES AND MORE UNSETTLED CONDITIONS TUE-THU THE REGIONAL PATTERN ALOFT WILL FEATURE INCREASING TROUGHINESS THROUGH THE MEDIUM RANGE PERIOD...WITH THE GLOBAL ENSEMBLE MEANS SHOWING A CORE OF NEGATIVE HEIGHT ANOMALIES OVER THE UPPER MIDWEST AND GREAT LAKES REGIONS BY THE MIDDLE TO LATER PART OF NEXT WEEK /SEPT 11-12TH/. OVERALL...THE NAEFS/GEFS AND ECENS ALL SIGNAL A TRANSITION TOWARD A HIGHER AMPLITUDE PATTERN PARTICULARLY ACROSS SOUTH CENTRAL CANADA. AN ELONGATED COLD FRONT TRAILING A RELATIVELY STRONG SFC LOW OVER NEWFOUNDLAND/LABRADOR WILL BE PASSING SOUTH OF PA SAT NIGHT. A MODIFIED CANADIAN HIGH BUILDING SWD INTO THE CENTRAL PLAINS WILL EVENTUALLY SHIFT EWD THROUGH THE NORTHEAST STATES AND MOVE INTO THE MARITIMES BY NEXT WED. SHRA/TSRA WILL END FROM NW-SE SAT NGT WITH MUCH DRIER AIR FILTERING IN FOR SUNDAY. DRY WX SHOULD CONTINUE INTO EARLY NEXT WEEK BEFORE CONDS TURN MORE UNSETTLED. EASTERLY WINDS TO THE SOUTH OF HP CELL MOVG INTO THE MARITIMES ARE SUGGESTIVE OF A COOL-AIR WEDGE OVER THE MID-ATLC WHICH SHOULD DAYTIME HIGHS NEAR AVG. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... ISOLATED TO SCT...MAINLY TOPOGRAPHICALLY ANCHORED...SLOW-MOVING PULSE SHOWERS AND TSRA WILL CONTINUE ACROSS MAINLY CENTRAL AND SRN PENN THROUGH 00Z SAT. LOCAL RESTRICTIONS WILL ACCOMPANY THIS CONVECTION. SKIES ARE CLEARING AND AS THE INVERSION STRENGTHENS THE WINDS WILL BECOME LIGHT TO CALM. HIGH DEWPOINTS REMAIN IN PLACE TONIGHT AHEAD OF AN APPROACHING COLD FRONT. THIS WILL ALSO BE ENHANCED DUE TO THE THUNDERSTORMS/RAIN SHOWERS ACROSS THE REGION TODAY. THIS WILL LEAD TO REDEVELOPMENT OF FOG/HAZE...AND AN ENCROACHING MVFR CLOUD DECK ALONG WITH A CHANCE FOR SHOWERS AFTER 06Z IN THE NW. AREAS OF LIFR ARE POSSIBLE ACROSS THE EASTERN TWO THIRDS OF THE STATE...WITH VLIFR POSSIBLE ACROSS SOME PORTIONS OF THE SUSQ VALLEY BETWEEN 09-13Z SATURDAY. NUMEROUS SHOWERS AND TSRA WITH OCNL RESTRICTIONS WILL OCCUR SATURDAY /MAINLY AFTER 18Z ACROSS THE SE...LOWER SUSQ VALLEY AIRFIELDS SUCH AS KMDT...KCXY...KLNS AND KTHV/. OUTLOOK... SUN...AM FOG POSS NW MTNS. MON...PATCHY AM VALLEY FOG POSS. TUE...CHC SHOWERS/TSTMS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT NEAR TERM...DANGELO/LAMBERT SHORT TERM...FITZGERALD/LAMBERT LONG TERM...FITZGERALD/GARTNER AVIATION...LAMBERT/CERU
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
835 AM EDT THU SEP 4 2014 .SYNOPSIS... HIGH PRESSURE OFF THE EAST COAST WILL CAUSE TO WARM AND HUMID AIR MOVING UP FROM THE SOUTH. THE MUGGY AIR WILL LAST INTO THE WEEKEND. A COLD FRONT WILL LIKELY PUSH SOUTH ACROSS THE REGION SATURDAY...FOLLOWED BY COOLER AIR DUE TO A CANADIAN HIGH PRESSURE AREA EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... HIGH PRESSURE AND LARGE SCALE SUBSIDENCE OVER THE REGION WAS LEADING TO GENERALLY CLEAR TO PTLY CLOUDY SKIES. THERE WERE A FEW SMALL AREAS OF BKN-OVC STRATO CU AND ALTO CU ACROSS THE FAR SE...AND FAR NW PARTS OF THE CWA. THE DEEPER VALLEYS CONTAINING LARGE STREAMS AND RIVERS ARE FOGGY...WITH LOCALIZED VSBYS UNDER 1/4SM. THE BULK OF THE CLOUDS WILL PROBABLY DRIFT NE ACROSS SCENT AND SERN SECTIONS OF THE CWA THROUGH THE MORNING HOURS...AND SPREAD INTO THE MID SUSQ REGION DURING THE MIDDAY AND AFTERNOON HOURS /WITHIN AN AREA OF 1-1.5 INCH PWAT AIR/. THE BROKEN CLOUDS WILL HAMPER HEATING A BIT...BUT THE 8H TEMPS IN THE MID TEENS WILL MAKE FOR A WARM DAY. TEMPS WILL MAX OUT ABOUT 5F ABOVE NORMAL. THE HEATING AND MOISTURE IN THE SOUTHERN AND CENTRAL MTS WILL POP ISOLD SHRA OFF THE HIGH HILLS. COVERAGE COULD BE ENOUGH FOR A 30 POP IN THE LAURELS/SC MTS. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... THE LIGHT S/SE WIND WILL TRY TO POOL MOISTURE UP IN THE CENTRAL MTS TONIGHT. NOCTURNAL COOLING WILL AGAIN LEAD TO SOME FOG IN THE VALLEYS...BUT THE EXTENT OF THE CLOUD COVER WILL LIMIT IT TO MAINLY THE NWRN MTS. THE MUGGY AIR WILL KEEP TEMPS FROM FALLING OUT OF THE MID 60S IN MANY PLACES BUT U50S STILL POSSIBLE IN THE NWRN MTS WHERE IT MAY BE MOST-CLEAR. FRIDAY SEEMS LIKE A MORE-LIKELY DAY FOR SOME CONVECTION AS THE CAPES COULD REACH 1500-2000 JOULES IF WE GET RID OF THE LID/CAP. BUT THE HIGH HEIGHTS AND WARM MID LEVELS WILL LIKELY LIMIT CONVECTION TO MAINLY THE S/E WHERE THE TEMPS COULD GET INTO THE U80S. LACK OF WIND IN THE PROFILE WILL KEEP THE WORRY OF SEVERE VERY LOW. A COLD FRONT WILL BE APPROACHING FROM THE GREAT LAKES ON FRIDAY NIGHT AND PUSH THRU ON SAT. THE POPS WILL STAY RATHER LOW OVER MOST OF THE AREA WITH ONLY SCT SHRA/TSRA OVERNIGHT. BUT THE NWRN COUNTIES WILL LIKELY SEE STROMS MOVE DOWN FROM THE NW AFTER MIDNIGHT. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... SUBTROPICAL RIDGE CENTERED OVER THE CAROLINAS WILL BE SUPPRESSED BY SHORTWAVE ENERGY AND MODERATE-INTENSITY SFC CYCLONE TRACKING NEWD FROM THE NRN HIGH PLAINS ACROSS WRN ONTARIO INTO NRN QUEBEC BY SAT. ITS TRAILING COLD FRONT REMAINS THE FOCUS FOR PCPN HEADING INTO THE WEEKEND WITH CONTINUED UNCERTAINTY IN THE SEWD FRONTAL PROGRESSION. A SLOWER TREND MAY BE EMERGING IN THE 12Z GFS/GEFS WITH ITS FRONTAL ZONE ALIGNING CLOSER WITH THE ECMWF/GEM BY 00Z SUN. MAX POPS SHIFT FROM NW TO SE OVER THE CWA FROM 06Z SAT TO 00Z SUN. HAVE RAISED POPS INTO THE LIKELY CATEGORY SAT BASED ON DIMINISHING SPREAD AMONGST MDL DATA...NEARLY ALL OF WHICH TRACK COLD FRONT THRU CENTRAL PA DURING THE DAYLIGHT HRS OF SATURDAY. AHEAD OF CDFRONT...TEMPS ARE LIKELY TO PEAK ON FRIDAY WITH MEAN H85 TEMPS +18-20C SUPPORTING WIDESPREAD HIGHS 85-90F. THE NEXT QUESTION CONCERNS HOW QUICKLY THE FRONT CLEARS SRN PA ON SUNDAY WITH MODEL DATA SUGGESTING THE UPPER LEVEL FRONT HANGS BACK ALONG THE APPLCHNS/MID-ATLC PIEDMONT...AS ENERGY IS SHEARED NEWD THRU THE NRN NEW ENGLAND AND CANADIAN MARITIMES AND FLOW ALOFT BECOMES ORIENTED MORE WESTERLY. MEAN PW FIELDS SHOW DRIER AIR SPREADING INTO THE REGION FROM THE NW BEHIND THE FRONT AS HIGH PRES BECOMES ESTABLISHED IN THE NORTHEAST BY EARLY NEXT WEEK. THEREFORE EXPECT TEMPS AND POPS TO TREND LOWER DURING THE LATER PERIODS. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... PATCHY DENSE FOG OBSERVED IN THE VALLEYS OF CENTRAL PA AT DAWN...WITH KAOO...KUNV AND KIPT ALL EXPERIENCING IFR OR LIFR CONDS AS OF 11Z. CLIMATOLOGY AND LATEST HRRR INDICATE FOG WILL BURN OFF BY 13Z-14Z AND MDL SOUNDINGS INDICATE A NEAR CERTAINTY OF WIDESPREAD VFR CONDS FOR THE REST OF TODAY...AS HIGH PRES PASSES EAST OF THE REGION. CLEAR SKIES AND A LIGHT WIND WILL PROMOTE AREAS OF FOG LATE TONIGHT WITH MANY LOCATIONS LIKELY TO EXPERIENCE A PERIOD OF IFR CONDS NEAR DAWN FRIDAY. OUTLOOK... FRI...PATCHY AM FOG. ISOLD PM TSRA IMPACTS POSS SOUTHERN PA. SAT...AM SHRA/LOW CIGS POSS NW MTNS. PM TSRA IMPACTS POSS ELSEWHERE. SUN...AM FOG POSS NW MTNS. MON...PATCHY AM VALLEY FOG POSS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DANGELO/LAMBERT NEAR TERM...DANGELO/LAMBERT SHORT TERM...DANGELO LONG TERM...LA CORTE AVIATION...FITZGERALD
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
601 AM MDT THU SEP 4 2014 .UPDATE... ISSUED AT 600 AM MDT THU SEP 4 2014 LOOKING AT LATEST RAP GUIDANCE AS WELL AS 12Z KUNR SOUNDING...WILL ALLOW FOOTHILLS WIND ADVISORY TO EXPIRE ON SCHEDULE. && .SHORT TERM...TODAY THROUGH FRIDAY NIGHT ISSUED AT 215 AM MDT THU SEP 4 2014 08Z SURFACE ANALYSIS HAD LOW NEAR KPIR WITH COLD FRONT DRIVING THROUGH CENTRAL NE INTO EASTERN CO. 3-6MB/3HR PRESSURE RISES BEHIND FRONT SUPPORTING GUSTY WINDS ON THE SD PLAINS EARLY THIS MORNING. AS BOUNDARY LAYER DECOUPLES AND PRESSURE RISES DECREASE EARLY THIS MORNING...THERE WILL BE A SMALL DECREASE IN WIND SPEEDS UNTIL A COUPLE OF HOURS AFTER SUNRISE WHEN MIXING WILL COMMENCE AGAIN AND GUSTY NORTHWEST WINDS WILL PICK BACK UP OVER THE NORTHWEST SD PLAINS. RAP/NAM/GFS SUGGEST 25-30KT BOUNDARY LAYER WINDS THROUGH EARLY AFTERNOON. WILL EXPAND ADVISORY FOR THESE AREAS. HAVE THE FOOTHILLS GOING UNTIL 600 AM...AND WILL DECIDE WHETHER TO EXTEND TO EXPIRE PRODUCT BASED ON 12Z OBSERVATIONS. TEMPERATURES WILL BE DRASTICALLY COOLER THAN YESTERDAY. TONIGHT...HIGH PRESSURE BUILDS INTO THE CWA. GOOD RADIATIONAL COOLING EXPECTED WITH PATCHY FROST OVER THE HIGHER BLACK HILLS POSSIBLE. FRIDAY...HIGH PRESSURE SHIFTS SOUTHEAST INTO THE LOWER MO RIVER VALLEY. WEAK RETURN FLOW SETS UP OVER THE CWA. LOW LEVEL THETA-E RIDGE OVER WY MAY SUPPORT AFTERNOON/EVENING -TSRA NEAR SOUTHWEST PORTIONS OF CWA...BUT POPS LOW ENOUGH TO LEAVE OUT SENSIBLE WEATHER AT THIS TIME. TEMPERATURES WILL REMAIN COOLISH. && .LONG TERM...SATURDAY THROUGH WEDNESDAY ISSUED AT 215 AM MDT THU SEP 4 2014 STRONG UPPER RIDGING WILL DEVELOP ACROSS THE WRN HALF OF THE CONUS FOR THE WEEKEND. THIS WILL BRING MOSTLY SUNNY SKIES AND WARMING TEMPS THROUGH SUNDAY. DID ADD SL CHC POPS TO THE BLKHLS SUNDAY. A BROAD UPPER TROF MOVES INTO THE WESTERN STATES EARLY NEXT WEEK WITH SOUTHWESTERLY FLOW DEVELOPING OVER THE HIGH PLAINS. COULD SEE SOME VERY ISOLATED THUNDERSTORM ACTIVITY SOMETIME EARLY NEXT WEEK...BUT TIMING AND PLACEMENT OF ACTIVITY IS PROBLEMATIC. MODELS HAVE BEEN SHOWING BETTER CHANCES FOR PRECIP TOWARD MIDWEEK WITH THE ECMWF BEING THE MUCH WETTER SOLUTION. HAVE ADJUSTED POPS BASED ON BEST GUESS...BUT WOULD STILL LIKE TO SEE BETTER MODEL CONSISTENCY. WITH BROAD TROF MOVING IN...TEMPERATURES WILL GRADUALLY DECREASE FROM MONDAY INTO THE MIDDLE OF NEXT WEEK. THE ECMWF IS BRINGING IN MUCH COLDER AIR INTO THE REGION WHILE THE GFS KEEPS THE COLD AIR WELL NORTH OF THE AREA. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 600 AM MDT THU SEP 4 2014 VFR CONDITIONS ARE EXPECTED THROUGH THE FORECAST PERIOD. GUSTY NW WINDS WILL CONTINUE TODAY OVER MUCH OF THE WRN SD PLAINS. WINDS WILL THEN DECREASE LATE THIS AFTN INTO THE EVNG. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...WIND ADVISORY UNTIL 3 PM MDT THIS AFTERNOON FOR SDZ001-002- 012>014-031-032-073. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...HELGESON LONG TERM...13 AVIATION...13
AREA FORECAST DISCUSSION
NWS MORRISTOWN TN
235 PM EDT THU SEP 4 2014 .SHORT TERM (TONIGHT AND FRIDAY)... A MOIST AIR MASS AND MIDLEVEL SHEAR ZONE BETWEEN TWO RIDGES WILL REMAIN OVER THE REGION THROUGH FRIDAY. WITH LITTLE PATTERN CHANGE...WILL FOLLOW MAINLY A PERSISTENCE FORECAST. THE NAM SEEMS TO BE PERFORMING PRETTY WELL WITH THE PATTERN...AND THE HRRR HAS BEEN RELIABLE IN DEPICTING AREAS OF AND TIMING OF CONVECTION. IT SHOWS ONGOING PRECIP LINGERING IN NE SECTIONS UNTIL DISSIPATING AROUND MIDNIGHT...AND WILL FOLLOW THAT SOLUTION FOR TONIGHT. AS WE SAW THIS MORNING...PATCHY FOG AND LOW CLOUDS CAN BE EXPECTED TO START THE DAY IN MOST SPOTS. THE ONE DIFFERENCE IN THE NAM TOMORROW APPEARS TO BE THAT THE 700 MB DEFORMATION/SHEAR ZONE SHIFTS SLIGHTLY TO THE SOUTH AND EAST...WHICH MAY LEAD TO SOUTHERN AND EASTERN AREAS BEING A BIT MORE FAVORED FOR AFTERNOON CONVECTION THAN NORTHERN AND WESTERN AREAS. STILL...WILL HAVE CHANCE POPS EVERYWHERE TOMORROW AFTERNOON. GFS MOS HIGH TEMPS APPEAR TOO WARM TOMORROW...AND HAVE VERIFIED TOO WARM THE PAST FEW DAYS...SO WILL UNDERCUT THEM BY SEVERAL DEGREES. .LONG TERM (FRIDAY NIGHT THROUGH THURSDAY)... A COLD FRONT WILL MOVE THROUGH THE AREA SATURDAY EVENING...WITH SHOWERS AND THUNDERSTORMS DEVELOPING THROUGH THE DAY SATURDAY AHEAD OF THIS FRONT. INSTABILITY AND SHEAR ARE UNIMPRESSIVE...SO LOOKING AT MAIN THREAT OF HEAVY RAIN WITH THESE STORMS. NEAR ZONAL FLOW WIL SET UP OVER THE AREA BEHIND THIS FRONT. THE AIRMASS DOES NOT YEILD MUCH CHANGE IN THE WAY OF COOLER TEMPERATURES SUNDAY THROUGH THE END OF THE PERIOD. BUT DOES HAVE DRIER AIR ADVECTED IN THE MIDLEVELS. THIS ALONG WITH THE AFTERNOON HEATING...EXPECTING TO SEE DIURNAL THUNDERSTORMS EACH DAY. UPPER LEVEL MOISTURE WILL CONTINUE TO INCREASE THROUGH THIS PERIOD...SO WILL ONLY SEE PARTLY CLOUDY SKIES FOR A DAY OR TWO AT THE BEGINNING OF THE WORK WEEK. THE NEXT BIG FEATURE MOVING INTO THE AREA IS ANOTHER COLD FRONT SET TO MOVE IN TOWARDS THE END OF NEXT WEEK. MODELS DIFFER ON TIMING AND STRENGTH OF THIS SYSTEM...SO SETTLED FOR CHANCE POPS THURSDAY AND FRIDAY. TEMPERATURES WILL BE A COUPLE OF DEGREES ABOVE NORMAL FOR THIS TIME OF YEAR. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 70 89 69 87 / 20 50 20 50 KNOXVILLE MCGHEE TYSON AIRPORT, TN 69 87 68 86 / 20 40 20 60 OAK RIDGE, TN 68 87 68 86 / 20 40 20 60 TRI CITIES AIRPORT, TN 66 87 64 86 / 40 40 20 60 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DGS/JW
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1243 PM CDT THU SEP 4 2014 .AVIATION 18Z DISCUSSION... A WEAK N-S MID/UPPER LEVEL TROUGH RESIDES ACROSS THE MID STATE THIS AFTERNOON. LOW LEVEL FETCH OF ADDED HUMIDITY WILL CONTINUE TO ALLOW FOR CONVECTIVE PARAMETERS TO BE MORE FAVORABLE...PARTICULARLY ACROSS EASTERN AREAS OF MIDDLE TN. AS A RESULT...A FEW SHOWERS AND TSTMS WILL BE POSSIBLE THIS AFTERNOON NEAR CSV. CURRENT TOVER VALUES ARE RUNNING SLIGHTLY NEGATIVE. WILL THEREFORE INCLUDE SOME LATE NIGHT FOG. TOMORROW...AROUND 18Z...CONVECTION MAY REFIRE NEAR CSV. WILL LEAVE THE MENTION OF CONVECTION OUT FOR NOW. && .PREV DISCUSSION... /ISSUED 932 AM CDT THU SEP 4 2014/ MORNING DISCUSSION UPDATE... LATEST STREAMLINE ANALYSIS CONTINUES TO SHOW A HUMID FLOW PATTERN IN THE LOWER LEVELS. NOT MUCH TO SPEAK OF AS FAR AS LOW LEVEL DYNAMICS. BUT...THE MID AND UPPER LEVEL PATTERN SHOWS WEAK N-S TROUGHING EXTENDING FROM THE NORTHERN GULF NORTHWARD ACROSS THE MID STATE. MRH PROFILES SHOW A DEFINITIVE MOIST TO DRY GRADIENT FROM EAST TO WEST. THIS WILL ALLOW CONVECTIVE PARAMETERS TO BE A LITTLE MORE FAVORABLE ACROSS OUR EASTERN COUNTIES FOR TODAY. LATEST HRRR IS IN LINE WITH THE CURRENT FCST AND SHOWS CONVECTION DEVELOPING ACROSS OUR EASTERN COUNTIES AROUND OR SHORTLY BEFORE NOON. QPF AVERAGES ACROSS THE EAST SHOULD BE ON THE LIGHT SIDE. CAPES DON`T LOOK IMPRESSIVE ENOUGH TODAY TO SUPPORT ANY STRONG ACTIVITY. AS FOR TEMPERATURES...LATEST NUMERICAL GUIDANCE AND EXPECTED TEMPS AT 15Z LOOK TO BE IN LINE WITH EXPECTED HIGHS. NO UPDATED NEEDED FOR NOW OTHER THAN TO REISSUE AND REMOVE THE MENTION OF FOG. STILL 3SM BR AT CKV BUT THIS SHOULD CONTINUE TO IMPROVE. OTW...IF THE ONSET OF CONVECTION IS FURTHER WEST THAN EXPECTED...WILL EXPAND THE WEATHER GRIDS A LITTLE FURTHER WESTWARD IF NEEDED. PREV DISCUSSION... /ISSUED 628 AM CDT THU SEP 4 2014/ UPDATE...FOR AVIATION. AVIATION... 12Z TAFS...LOOKING FOR MAINLY VFR TODAY. DENSE FOG CURRENTLY AT CKV WILL LIFT BY 14Z. SCT TSRA OVER THE PLATEAU THIS AFTERNOON...SO INCLUDING VCTS FOR CSV. OTHERWISE...SCT CUMULUS CLOUDS TODAY WITH S WINDS NEAR 6KT. PATCHY FOG EXPECTED TONIGHT...MAINLY MVFR...BUT CKV COULD GO DOWN TO LIFR AGAIN. 13 PREV DISCUSSION... /ISSUED 308 AM CDT THU SEP 4 2014/ DISCUSSION... FORECAST QUANDARIES...POTENTIAL FOR PATCHY DENSE FOG FORMATION THIS MORNING... SHWR/TSTMS CHANCES...ANY MODEL TIMING DIFFERENCES IN OVERALL WX PATTERN THIS WEEKEND...TEMPS. AS THRU THE MID MORNING HRS FOR TODAY...WILL BE MONITORING THIS MORNING PATCHY FOG FORMATION THRU AND AROUND PRESS TIME...WITH VSBYS ALREADY BELOW ONE MILE IN SOME SELECTED LOCATIONS ACROSS SRN PORTIONS OF MID STATE. THREE SCENARIOS COULD PLAY OUT...JUST MENTIONING PATCHY FOG THRU THE MID MORNING HRS IN THE SUITE OF FORECAST PRODUCTS...POSSIBLE ISSUANCE OF AN SPS DEALING WITH LOCALLY DENSE FOG FORMATION THRU MID MORNING HRS...OR A DENSE FOG ADVISORY FOR A PORTIONS/ALL OF MID STATE. NO MATTER WHAT...DEWPOINT DEPRESSIONS...CALM WINDS...AND CLRING SKIES ARE ALL FAVORABLE THRU THE MID MORNING HRS FOR FOG FORMATION. KEY TO MORE WIDESPREAD PATCHY TO DENSE FOG DEVELOPMENT ACROSS PLATEAU REGION WILL BE IF THERE IS ANY BREAKS/EROSION OF CLOUD COVERAGE PRESENTLY ACROSS PLATEAU COUNTIES... WHERE SHORT RANGE MODEL CONSENSUS ALONG WITH CURRENT SATELLITE TRENDS SHOWING CURRENT CLOUD COVERAGE TRENDS AT LEAST GENERALLY MAINTAIN ITSELF THRU THE MID MORNING HOURS. WILL BE WATCHING THIS CAREFULLY ON WHAT DECISION TO DO CONCERNING FOG FORMATION OVER THIS PORTION OF THE MID STATE. WHATEVER DECISION IS FINALLY MADE HERE...WILL ALSO HIGHLIGHT IT IN THE MORNING`S HAZARDOUS WEATHER OUTLOOK. AS FOR THE MID MORNING HRS TODAY THRU FRI NIGHT...MODEL CONSENSUS CONTINUES TO SHOW RIDGING INFLUENCES SFC/ALOFT ALONG WITH A CONTINUANCE OF PLENTIFUL LOW LEVEL MOISTURE INTERACTING WITH DIURNAL INFLUENCES AND LOCAL OROGRAPHIC EFFECTS...RESULTING IN A TYPICAL SUMMERTIME PATTERN FOR THE MID STATE THRU FRI WITH MAINLY LATE MORNING THRU EARLY EVENING SHWRS/TSTMS...WITH THE BEST CHANCE OF SHWRS/TSTMS ACROSS ERN PORTIONS INCLUDING PLATEAU REGION WHERE BEST OVERALL MOISTURE WILL CONTINUE TO BE USHERED INTO MID STATE AREA PER THIS MOISTURE BEING ON PERIPHERY OF SFC BERMUDA HIGH PRESSURE INFLUENCES. WILL ALSO CONTINUE LEANING TOWARD THE WARMER GFS MOS SOLUTION ON HIGHS WITH THIS SUMMER TIME PATTERN...LOWER 90S... MID TO UPPER 80S PLATEAU WITH LOWS AROUND 70...UPPER 60S PLATEAU. WILL KEEP A SLIGHT CHANCE TO CHANCE OF SHWRS/TSTMS THRU FRI NIGHT AS MOISTURE POOLS AND SHORTWAVE APPROACHES. AS FOR THE WEEKEND INTO THE FIRST PART OF NEXT WEEK...STILL LOOKS LIKE ANOTHER RATHER WEAK SFC FRONT IS EXPECTED TO PASS THRU THE MID STATE AS SAT PROGRESSES WITH ANOTHER SHORTWAVE PASSAGE RESULTING IN SCT SHWRS/TSTMS ACROSS THE MID STATE FROM AT LEAST THE LATE MORNING HRS THRU POSSIBLY THE ENTIRE EVENING HRS. A GOOD MODEL CONSENSUS HAS BEEN REACHED WITH THESE FEATURES NOW. ALSO...FROM TODAY THRU SAT...WOULD NOT BE SURPRISED FOR A FEW TSTMS TO AT LEAST REACH STRONG THRESHOLDS...AND WILL MENTION THIS IN THE MORNING HAZARDOUS WEATHER OUTLOOK ISSUANCE ALSO. MID-UPPER MS RIVER VALLEY 1020MB SFC HIGH PRESSURE PATTERN WILL BEGIN INFLUENCING THE MID STATE`S WEATHER BY SUN RESULTING IN A TREND BACK TOWARD TEMPS BEING MORE AROUND SEASONABLE NORMAL VALUES. LATEST GFS MOS GUIDANCE COMING MORE IN LINE WITH PREVIOUS RUNS OF THE EURO SOLUTION WITH TEMPS NEAR SEASONABLE NORMAL VALUES THRU THE MID PORTION OF NEXT WEEK. WILL CONTINUE WITH A SLIGHT CHANCE OF DIURNALLY DRIVEN SHWRS/TSTMS SUN INTO MON AS QUASI ZONAL FLOW ALOFT AIDING IN PASSAGES OF ADDITIONAL SHORTWAVES IN FLOW ALOFT. THERE ARE SOME TIMING DIFFERENCES BETWEEN THE LATEST GFS/DGEX AND EURO IN WHEN POTENTIALLY MORE SIGNIFICANT SHORTWAVE PASSAGE IS EXPECTED THRU THE MID PORTION OF NEXT WEEK...BUT WILL CONTINUE WITH A GENERALLY TREND OF TREND TOWARD SCT SHWRS/TSTMS THRU WED AS SFC PATTERN BECOMES MORE SLY ORIENTATED IN NATURE USHERING IN ADDITIONAL MOISTURE TO MID STATE. 31 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 21
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
932 AM CDT THU SEP 4 2014 .MORNING DISCUSSION UPDATE... LATEST STREAMLINE ANALYSIS CONTINUES TO SHOW A HUMID FLOW PATTERN IN THE LOWER LEVELS. NOT MUCH TO SPEAK OF AS FAR AS LOW LEVEL DYNAMICS. BUT...THE MID AND UPPER LEVEL PATTERN SHOWS WEAK N-S TROUGHING EXTENDING FROM THE NORTHERN GULF NORTHWARD ACROSS THE MID STATE. MRH PROFILES SHOW A DEFINITIVE MOIST TO DRY GRADIENT FROM EAST TO WEST. THIS WILL ALLOW CONVECTIVE PARAMETERS TO BE A LITTLE MORE FAVORABLE ACROSS OUR EASTERN COUNTIES FOR TODAY. LATEST HRRR IS IN LINE WITH THE CURRENT FCST AND SHOWS CONVECTION DEVELOPING ACROSS OUR EASTERN COUNTIES AROUND OR SHORTLY BEFORE NOON. QPF AVERAGES ACROSS THE EAST SHOULD BE ON THE LIGHT SIDE. CAPES DON`T LOOK IMPRESSIVE ENOUGH TODAY TO SUPPORT ANY STRONG ACTIVITY. AS FOR TEMPERATURES...LATEST NUMERICAL GUIDANCE AND EXPECTED TEMPS AT 15Z LOOK TO BE IN LINE WITH EXPECTED HIGHS. NO UPDATED NEEDED FOR NOW OTHER THAN TO REISSUE AND REMOVE THE MENTION OF FOG. STILL 3SM BR AT CKV BUT THIS SHOULD CONTINUE TO IMPROVE. OTW...IF THE ONSET OF CONVECTION IS FURTHER WEST THAN EXPECTED...WILL EXPAND THE WEATHER GRIDS A LITTLE FURTHER WESTWARD IF NEEDED. && .PREV DISCUSSION... /ISSUED 628 AM CDT THU SEP 4 2014/ UPDATE...FOR AVIATION. AVIATION... 12Z TAFS...LOOKING FOR MAINLY VFR TODAY. DENSE FOG CURRENTLY AT CKV WILL LIFT BY 14Z. SCT TSRA OVER THE PLATEAU THIS AFTERNOON...SO INCLUDING VCTS FOR CSV. OTHERWISE...SCT CUMULUS CLOUDS TODAY WITH S WINDS NEAR 6KT. PATCHY FOG EXPECTED TONIGHT...MAINLY MVFR...BUT CKV COULD GO DOWN TO LIFR AGAIN. 13 PREV DISCUSSION... /ISSUED 308 AM CDT THU SEP 4 2014/ DISCUSSION... FORECAST QUANDARIES...POTENTIAL FOR PATCHY DENSE FOG FORMATION THIS MORNING... SHWR/TSTMS CHANCES...ANY MODEL TIMING DIFFERENCES IN OVERALL WX PATTERN THIS WEEKEND...TEMPS. AS THRU THE MID MORNING HRS FOR TODAY...WILL BE MONITORING THIS MORNING PATCHY FOG FORMATION THRU AND AROUND PRESS TIME...WITH VSBYS ALREADY BELOW ONE MILE IN SOME SELECTED LOCATIONS ACROSS SRN PORTIONS OF MID STATE. THREE SCENARIOS COULD PLAY OUT...JUST MENTIONING PATCHY FOG THRU THE MID MORNING HRS IN THE SUITE OF FORECAST PRODUCTS...POSSIBLE ISSUANCE OF AN SPS DEALING WITH LOCALLY DENSE FOG FORMATION THRU MID MORNING HRS...OR A DENSE FOG ADVISORY FOR A PORTIONS/ALL OF MID STATE. NO MATTER WHAT...DEWPOINT DEPRESSIONS...CALM WINDS...AND CLRING SKIES ARE ALL FAVORABLE THRU THE MID MORNING HRS FOR FOG FORMATION. KEY TO MORE WIDESPREAD PATCHY TO DENSE FOG DEVELOPMENT ACROSS PLATEAU REGION WILL BE IF THERE IS ANY BREAKS/EROSION OF CLOUD COVERAGE PRESENTLY ACROSS PLATEAU COUNTIES... WHERE SHORT RANGE MODEL CONSENSUS ALONG WITH CURRENT SATELLITE TRENDS SHOWING CURRENT CLOUD COVERAGE TRENDS AT LEAST GENERALLY MAINTAIN ITSELF THRU THE MID MORNING HOURS. WILL BE WATCHING THIS CAREFULLY ON WHAT DECISION TO DO CONCERNING FOG FORMATION OVER THIS PORTION OF THE MID STATE. WHATEVER DECISION IS FINALLY MADE HERE...WILL ALSO HIGHLIGHT IT IN THE MORNING`S HAZARDOUS WEATHER OUTLOOK. AS FOR THE MID MORNING HRS TODAY THRU FRI NIGHT...MODEL CONSENSUS CONTINUES TO SHOW RIDGING INFLUENCES SFC/ALOFT ALONG WITH A CONTINUANCE OF PLENTIFUL LOW LEVEL MOISTURE INTERACTING WITH DIURNAL INFLUENCES AND LOCAL OROGRAPHIC EFFECTS...RESULTING IN A TYPICAL SUMMERTIME PATTERN FOR THE MID STATE THRU FRI WITH MAINLY LATE MORNING THRU EARLY EVENING SHWRS/TSTMS...WITH THE BEST CHANCE OF SHWRS/TSTMS ACROSS ERN PORTIONS INCLUDING PLATEAU REGION WHERE BEST OVERALL MOISTURE WILL CONTINUE TO BE USHERED INTO MID STATE AREA PER THIS MOISTURE BEING ON PERIPHERY OF SFC BERMUDA HIGH PRESSURE INFLUENCES. WILL ALSO CONTINUE LEANING TOWARD THE WARMER GFS MOS SOLUTION ON HIGHS WITH THIS SUMMER TIME PATTERN...LOWER 90S... MID TO UPPER 80S PLATEAU WITH LOWS AROUND 70...UPPER 60S PLATEAU. WILL KEEP A SLIGHT CHANCE TO CHANCE OF SHWRS/TSTMS THRU FRI NIGHT AS MOISTURE POOLS AND SHORTWAVE APPROACHES. AS FOR THE WEEKEND INTO THE FIRST PART OF NEXT WEEK...STILL LOOKS LIKE ANOTHER RATHER WEAK SFC FRONT IS EXPECTED TO PASS THRU THE MID STATE AS SAT PROGRESSES WITH ANOTHER SHORTWAVE PASSAGE RESULTING IN SCT SHWRS/TSTMS ACROSS THE MID STATE FROM AT LEAST THE LATE MORNING HRS THRU POSSIBLY THE ENTIRE EVENING HRS. A GOOD MODEL CONSENSUS HAS BEEN REACHED WITH THESE FEATURES NOW. ALSO...FROM TODAY THRU SAT...WOULD NOT BE SURPRISED FOR A FEW TSTMS TO AT LEAST REACH STRONG THRESHOLDS...AND WILL MENTION THIS IN THE MORNING HAZARDOUS WEATHER OUTLOOK ISSUANCE ALSO. MID-UPPER MS RIVER VALLEY 1020MB SFC HIGH PRESSURE PATTERN WILL BEGIN INFLUENCING THE MID STATE`S WEATHER BY SUN RESULTING IN A TREND BACK TOWARD TEMPS BEING MORE AROUND SEASONABLE NORMAL VALUES. LATEST GFS MOS GUIDANCE COMING MORE IN LINE WITH PREVIOUS RUNS OF THE EURO SOLUTION WITH TEMPS NEAR SEASONABLE NORMAL VALUES THRU THE MID PORTION OF NEXT WEEK. WILL CONTINUE WITH A SLIGHT CHANCE OF DIURNALLY DRIVEN SHWRS/TSTMS SUN INTO MON AS QUASI ZONAL FLOW ALOFT AIDING IN PASSAGES OF ADDITIONAL SHORTWAVES IN FLOW ALOFT. THERE ARE SOME TIMING DIFFERENCES BETWEEN THE LATEST GFS/DGEX AND EURO IN WHEN POTENTIALLY MORE SIGNIFICANT SHORTWAVE PASSAGE IS EXPECTED THRU THE MID PORTION OF NEXT WEEK...BUT WILL CONTINUE WITH A GENERALLY TREND OF TREND TOWARD SCT SHWRS/TSTMS THRU WED AS SFC PATTERN BECOMES MORE SLY ORIENTATED IN NATURE USHERING IN ADDITIONAL MOISTURE TO MID STATE. 31 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 21
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
940 PM CDT FRI SEP 5 2014 .UPDATE... SEE DISCUSSION FOR EVENING UPDATE. && .DISCUSSION... SHOWERS AND THUNDERSTORMS HAVE COME TO AN END THIS EVENING. FORECAST SOUNDINGS FOR TOMORROW DON`T LOOK TO FAVORABLE FOR RAIN CHANCES WITH AVERAGE MOISTURE AND LOW K INDEX VALUES. UPPER LEVEL WINDS ALSO SHOW A LIGHT CONFLUENT PATTERN. AT 500MB THOUGH A POCKET OF VORTICITY IS FORECASTED TO BREAK AND WASH OVER THE COAST TOMORROW. FORECAST SOUNDINGS ALSO SHOW PLENTY OF INSTABILITY. HIGH RES TEXAS TECH WRF AND RAP SHOWS COVERAGE INCREASING TOMORROW AFTERNOON. THINK CHANCE POPS ARE THE WAY TO GO GIVEN THE INSTABILITY IN FORECAST SOUNDINGS. CURRENT FORECAST HAS THIS COVERED. NO UPDATE REQUIRED AT THIS TIME. 23 && .PREV DISCUSSION... /ISSUED 630 PM CDT FRI SEP 5 2014/ DISCUSSION... SEE 00Z AVIATION DISCUSSION. AVIATION... SHRA/TSRA ARE JUST TO THE WEST OF KIAH BUT THIS ACTIVITY IS EXPECTED TO WANE BY 00Z SO WILL NOT MENTION IN THE TAF. MOST OF THE SHRA/TSRA ARE DISSIPATING QUICKLY WITH THE LOSS OF HEATING. HIGH CLOUDS WILL ALSO ERODE THIS EVENING. MODELS ARE TRENDING A BIT DRIER WITH PWATS FALLING TO 1.7-1.8 INCHES FOR SATURDAY. CONVECTIVE TEMPS ARE BETWEEN 86-89 DEGREES NEAR THE COAST AND 89-92 DEGREES INLAND. WILL CARRY VCTS STARTING AT 12Z AT KGLS AND 15-17Z KSGR/KHOU/KIAH AND 18-19Z KUTS/KCLL. WINDS WILL REMAIN LIGHT EXCEPT IN AND NEAR STORMS. 43 PREV DISCUSSION... /ISSUED 352 PM CDT FRI SEP 5 2014/ DISCUSSION... A FAIRLY DEEP UPPER LEVEL RIDGE WILL REMAIN OVER SE TX FOR MOST OF THE UPCOMING FORECAST PERIOD. A WEAKNESS IN THE RIDGE WILL MOVE OVER SE TX FROM THE EAST AS A COLD FRONT DROPS SOUTHWARD TOWARD THE FORECAST AREA. THIS WILL HELP KEEP SCATTERED THUNDERSTORM CHANCES IN PLACE THROUGH SUNDAY. THE RIDGE WILL BUILD AGAIN OVERHEAD THROUGH MID WEEK. TOWARD THE END OF THE WORK WEEK...A STRONGER COLD FRONT MAY APPROACH THE AREA FROM THE NORTH. MODEL FORECAST SOUNDINGS SHOW A SIMILAR SETUP FOR WHAT OCCURRED TODAY FOR SATURDAY. WITH NO CAP...PW/S NEAR 2 INCHES...AND FORECAST CAPE VALUES OF 3000 TO 3500...EXPECT THAT ISOLATED STRONG THUNDERSTORMS WILL BE AGAIN POSSIBLE. THE MAIN THREAT WILL BE STRONG GUSTY WINDS IN EXCESS OF 40 MPH...FREQUENT CLOUD-TO-GROUND LIGHTNING...AND LOCALLY HEAVY RAINFALL. THE HIGH RESOLUTION ARW AND NMM BOTH FORECAST THE COLD FRONT TO APPROACH THE NORTHERN COUNTIES DURING THE EVENING. THIS MAY HELP TO KEEP AT LEAST ISOLATED STORMS ACROSS THE FORECAST AREA SATURDAY NIGHT. THE GLOBAL MODELS DO NOT PUSH THE FRONT ALL THE WAY THROUGH THE AREA ON SUNDAY AND THEN MOVE IT BACK NORTH LATE SUNDAY INTO MONDAY. THIS SHOULD KEEP SCATTERED STORMS ON SUNDAY AND ISOLATED CHANCES ON MONDAY. FOR TUESDAY AND WEDNESDAY THE RIDGE WILL LIKELY KEEP RAIN CHANCES TO A MINIMUM. THE GFS AND ECMWF THEN DIFFER FOR THURSDAY...WITH THE GFS FASTER WITH THE APPROACH OF THE NEXT COLD FRONT THURSDAY EVENING. WOULD LIKE TO SEE A BIT BETTER MODEL CONSISTENCY...PLUS FELT THAT THE SLOWER ECMWF MAY BE THE BETTER MODEL GIVEN THE UPPER LEVEL PATTERN. BOTH MODELS HAVE SWITCHED FROM A NORTHWESTERLY FLOW TO KEEP THE CENTER OF THE RIDGE A BIT FURTHER TO THE NORTH. 40 MARINE... LIGHT ONSHORE WINDS WILL PERSIST THRU THE WEEKEND. PRESSURE GRADIENT WILL BE WEAK ENOUGH TOWARD THE END OF THE WEEKEND AND EARLY NEXT WEEK THAT WE`LL PROBABLY SEE A DISTINCT LANDBREEZE/ SEABREEZE CIRCULATION (BRIEF OFFSHORE FLOW LATE AT NIGHT & EARLY MORNING BECOMING ONSHORE DURING THE DAY). OTHERWISE...SCATTERED SHOWERS/TSTMS CAN BE EXPECTED EACH DAY. MOST FAVORED TIMES BETWEEN 2- 10AM. 47 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 74 95 74 94 74 / 30 40 20 30 20 HOUSTON (IAH) 75 92 75 93 74 / 30 40 20 30 20 GALVESTON (GLS) 82 90 80 89 78 / 30 30 20 30 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ DISCUSSION...23
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
935 PM CDT FRI SEP 5 2014 .UPDATE... STILL SOME UPPER DIVERGENCE OVER SOUTHERN WISCONSIN FROM THE RIGHT ENTRANCE REGION OF THE 250 MB JET MAX. THE 700 MB UPWARD MOTION DIMINISHES THROUGH THE NIGHT. 700 MB RH DECREASES WITH THE SATURATION OCCURRING ACROSS NORTHEAST ILLINOIS AND FAR SOUTHERN LAKE MICHIGAN THROUGH MIDNIGHT. THEN THIS DRIES WITH 700 MB RH BELOW 20 PCT EVEN IN THE FAR SOUTHEAST AROUND SUNRISE. AS A RESULT THE RADAR RETURNS SHOULD BE MAINLY VIRGA THIS EVENING...WITH CLEARING SKIES BY SUNRISE EXCEPT FOR SOME CIRRUS. NORTHWEST LOW LEVEL GRADIENT SHOULD PREVENT FOG MOST AREAS...EXCEPT PERHAPS IN THE WISCONSIN RIVER VALLEY. && .AVIATION/06Z TAFS/... MID LEVEL VFR CLOUDS SHOULD GRADUALLY CLEAR WITH MAINLY CIRRUS BY SUNRISE. MAINLY VFR VSBYS EXCEPT IFR FOG POSSIBLE MAINLY IN THE WISCONSIN RIVER VALLEY. VFR CONDITIONS ON SATURDAY AS HIGH PRESSURE BUILDS ACROSS THE MID MISSISSIPPI RIVER VALLEY. && .PREV DISCUSSION... /ISSUED 338 PM CDT FRI SEP 5 2014/ TONIGHT AND SATURDAY...FORECAST CONFIDENCE IS HIGH. CONVECTION ASSOCIATED WITH SURFACE COLD FRONT PUSHED THROUGH KENOSHA COUNTY IN THE PAST HOUR...AND IS NOW MOVING AWAY FROM THAT AREA. AREA OF SHOWERS AND ISOLATED THUNDERSTORMS CONTINUES TO PUSH NORTHEAST INTO THE AREA FROM EASTERN IOWA AND FAR NORTHWEST ILLINOIS. THIS IS ASSOCIATED WITH LOW LEVEL FRONTOGENESIS RESPONSE FIELDS AND UPPER DIVERGENCE FROM RIGHT REAR QUADRANT OF 250 MB JET STREAK. THESE FEATURES SHOULD SLIDE ACROSS A GOOD PORTION OF THE AREA INTO EARLY THIS EVENING. SO...BROUGHT IN HIGHER POPS FOR SHOWERS AND ISOLATED STORMS ACROSS A GOOD PORTION OF THE AREA. THIS IS SUPPORTED BY LATEST HRRR RUN AND WRF NMM/ARW MODELS. WENT WITH MORE SCATTERED TO NUMEROUS SHOWER WORDING...AS THEY WILL HAVE TO BATTLE DRYING LOW LEVEL AIR ACROSS THE AREA. PRECIPITATION SHOULD EXIT THE AREA BY MIDDLE EVENING...WITH SKIES BECOMING MOSTLY CLEAR FROM WEST TO EAST LATER TONIGHT INTO SATURDAY MORNING. HIGH PRESSURE SLIDING EAST TOWARD THE REGION WILL BRING QUIET WEATHER INTO SATURDAY. LOWS TONIGHT SHOULD DROP INTO THE LOWER 50S INLAND...WITH MILDER READINGS NEAR THE LAKE. HIGHS SHOULD REACH THE LOWER 70S ON SATURDAY. SATURDAY NIGHT THROUGH MONDAY - CONFIDENCE HIGH... ALL MODELS SHOW HIGH PRESSURE CENTERED OVER THE CENTRAL PLAINS SATURDAY NIGHT EXPANDING OVER THE GREAT LAKES SUNDAY AND CONTINUE TO BUILD NORTHEASTWARD THROUGH MONDAY. THIS WILL BRING MOSTLY CLEAR SKIES..LIGHT WINDS...DRIER CONDITIONS. HIGH TEMPERATURES NEAR NORMAL...IN THE MID 70S. GOOD RADIATIONAL COOLING CONDITIONS WILL ALLOW OVERNIGHT LOW TEMPERATURES TO DROP SLIGHTLY BELOW NORMAL...LOW 50S. MONDAY NIGHT THROUGH THURSDAY - CONFIDENCE...MEDIUM LOW PRESSURE DEVELOPING WEST THE AREA MONDAY NIGHT AND APPROACHING THE REGION TUESDAY CREATES A SOUTHWESTERLY FLOW AND SIGNIFICANT MOISTURE ADVECTION WITH CHANCE OF SHOWERS DEVELOPING MONDAY NIGHT AND INCREASING TUESDAY. SURFACE LOW PRESSURE DEEPENING OVER THE AREA TUESDAY NIGHT AND SLOWLY MOVING NORTHEASWARD AND DEEPENING ACROSS THE GREAT LAKES REGION THROUGH THURSDAY. THIS LOW COMBINED WITH MULTIPLE UPPER LEVEL SHORT WAVES SHOULD KEEP UNSETTLED WEATHER AND A CHANCE OF RAINSHOWERS AND SOME THUNDERSTORMS THROUGHOUT THE MIDDLE OF NEXT WEEK. THURSDAY NIGHT AND FRIDAY - CONFIDENCE...MEDIUM STRONG HIGH PRESSURE EXPECTED TO DEVELOP OVER THE CENTRAL AND NORTHERN PLAINS AND LOW PRESSURE CENTER REMAINING OVER SOUTHEAST CANADA WILL PRODUCE NORTHWEST FLOW ACROSS WISCONSIN. THIS WILL BRING DRIER BUT SIGNIFICANTLY COOLER AIR TO THE AREA FRIDAY AND INTO THE WEEKEND. THURSDAY NIGHT LOWS IN THE 40S. HIGH TEMPERATURES FRIDAY MAY STRUGGLE TO REACH 60. AVIATION/00Z TAFS/... SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED UNTIL AROUND 03Z SATURDAY ACROSS TAF SITES...AS A TROUGH OF LOW PRESSURE MOVES THROUGH THE REGION. CEILINGS SHOULD BECOME VFR CATEGORY DURING THIS TIME. MODERATE NORTHWEST WINDS WITH SOME GUSTS TO AROUND 15 KNOTS WILL LINGER UNTIL AROUND 00Z SATURDAY. HIGH PRESSURE MOVING EAST TOWARD THE REGION LATER TONIGHT INTO SATURDAY WILL BRING QUIET WEATHER TO THE AREA. SKIES SHOULD BECOME MOSTLY CLEAR BY LATER TONIGHT OR EARLY SATURDAY. WINDS WILL BECOME LIGHT OUT OF THE NORTH TO NORTHWEST DURING THIS TIME. MARINE... NORTHWEST WINDS OF 10 TO 15 KNOTS WILL LINGER UNTIL AROUND 00Z SATURDAY. MAY SEE A FEW GUSTS TO 20 KNOTS. WINDS WILL DIMINISH TONIGHT WITH WEAKENING PRESSURE GRADIENT. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ UPDATE...HENTZ TONIGHT/SATURDAY AND AVIATION/MARINE...WOOD SATURDAY NIGHT THROUGH FRIDAY...SLB
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
615 PM CDT FRI SEP 5 2014 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 353 PM CDT FRI SEP 5 2014 AT 3 PM...A STRONG CANADIAN COLD FRONT EXTENDED FROM NEW BERLIN WISCONSIN SOUTHWEST TO WEATHERFORD OKLAHOMA /KOJA/. TEMPERATURE AHEAD OF THIS COLD FRONT RANGED FROM THE MID 80S TO MID 90S WITH DEW POINTS IN THE 70S. MEANWHILE BEHIND THIS COLD FRONT... TEMPERATURES WERE IN THE 60S AND 70S WITH DEW POINTS IN THE 50S. A BAND OF 900 TO 700 MB FRONTOGENESIS IS GENERATING A BAND OF SHOWERS ACROSS PARTS OF NORTHEAST IOWA AND SOUTHWEST WISCONSIN. IN ADDITION WITH THE RAP SHOWING MOST UNSTABLE CAPES UP TO 500 J/KG AND SOME SLANTWISE CONVECTION...KEPT ISOLATED THUNDERSTORMS IN THE FORECAST. WITH FAIRLY LIMITED MOST UNSTABLE CAPES AND UNFAVORABLE 0-3 KM OR 0-6 KM SHEAR...NOT ANTICIPATING ANY OF THESE THUNDERSTORMS TO BECOME SEVERE. MEANWHILE FURTHER NORTHWEST ACROSS SOUTHEAST MINNESOTA...700 TO 500 MB FRONTOGENESIS IS PRODUCING ANOTHER BAND OF SHOWERS. FOR EARLY THIS EVENING...THE RAP SHOWS THAT THE 2 BANDS OF FRONTOGENESIS WILL MOVE QUICKLY SOUTHEAST OF THE FORECAST AREA BY 06.03Z. AS THIS OCCURS...THE SHOWERS AND ISOLATED THUNDERSTORMS WILL MOVE OUT OF THE AREA. AS A RESULT...WENT WITH A QUICK LOWERING OF THE PRECIPITATION PROBABILITIES FROM WEST TO EAST ACROSS SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND IN WESTERN WISCONSIN SOUTH OF INTERSTATE 90 BETWEEN 05.23Z AND 06.03Z. IN ADDITION TO THIS...THE CLOUDS SHOULD BE QUICKLY ON THE DECREASE. FOR LATE TONIGHT...THE BUFKIT SOUNDINGS SHOW A SHALLOW LAYER /A COUPLE OF HUNDRED FEET/ OF LIGHT WINDS WITH 10 TO 20 KNOTS ABOVE 300 FEET. THESE WINDS SHOULD MAKE IT UNFAVORABLE FOR THE DEVELOPMENT OF FOG TONIGHT. ON SATURDAY...BUFKIT SOUNDINGS SHOW VERY STEEP 900 TO 750 MB LAPSE RATES /9-10 C/KM/ ACROSS THE AREA. THIS WILL ALLOW THE WIND GUSTS TO CLIMB INTO THE 10 TO 20 KNOT RANGE. IN ADDITION...THIS WILL ALLOW DRIER AIR FROM ALOFT TO MIX TO THE SURFACE. AS A RESULT... LOWERED THE DEW POINTS INTO THE 45 TO 50 DEGREE RANGE. THIS STILL MAY BE ON THE HIGH SIDE...BUT THE TREND IS IN THE RIGHT DIRECTION. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 353 PM CDT FRI SEP 5 2014 FROM LATE SATURDAY NIGHT INTO SUNDAY MORNING...THE LAYER OF LIGHT WINDS ONCE AGAIN LOOK VERY SHALLOW. IN ADDITION...THE DEW POINTS ARE SHOWING A SLOW RECOVERY. AS A RESULT...UNCERTAIN OF WHETHER ANY VALLEY FOG WILL OCCUR OR NOT. SO JUST WENT WITH PATCHY FOG IN THE RIVER VALLEY AND THE CRANBERRY BOGS OF CENTRAL WISCONSIN. ON SUNDAY AFTERNOON...BUFKIT SOUNDINGS SHOW VERY STEEP 900 TO 750 MB LAPSE RATES /8-10 C/KM/ ACROSS THE AREA. THIS WILL ALLOW DRIER AIR FROM ALOFT TO MIX TO THE SURFACE. AS A RESULT...LOWERED THE DEW POINTS INTO THE 45 TO 50 DEGREE RANGE. FROM MONDAY AFTERNOON THROUGH WEDNESDAY...THE MODELS CONTINUE TO SHOW THAT A SERIES OF SHORT WAVE TROUGHS WILL MOVE THROUGH THE REGION. DUE TO RUN TO RUN MODEL INCONSISTENCIES...THE TIMING OF THESE WAVES IS STILL A BIT UNCERTAIN...SO KEPT BROAD BRUSHED THE PRECIPITATION CHANCES DURING THIS TIME FRAME. WITH MOST UNSTABLE CAPES LESS THAN 750 J/KG...KEPT THE THUNDERSTORM CHANCES AS ISOLATED. WHEN THE 0-3 KM TO 0-6 KM SHEAR DOES BECOME FAVORABLE FOR THE DEVELOPMENT OF SUPERCELLS...THERE IS VERY LITTLE INSTABILITY. AS A RESULT...NOT ANTICIPATING ANY SEVERE WEATHER. ON WEDNESDAY NIGHT...A STRONG CANADIAN COLD FRONT WILL MOVE SOUTH THROUGH THE FORECAST AREA. BEHIND THIS FRONT...850 MB TEMPERATURES WILL FALL INTO THE 0 TO -4C RANGE AND REMAIN IN THIS RANGE INTO THE WEEKEND. THIS IS NEARLY 2 STANDARD DEVIATIONS BELOW NORMAL. IT CONTINUES TO LOOK LIKE...HIGH TEMPERATURES WILL BE AROUND 60 ON THURSDAY...AND ONLY IN THE 50S FOR FRIDAY. WHILE THERE IS AGREEMENT IN THE ECMWF AND GFS ON THESE HIGH TEMPERATURES...THEY ARE STILL RUNNING 10 DEGREES APART ON THE LOW TEMPERATURES FOR THURSDAY NIGHT AND FRIDAY NIGHT. THE ECMWF HAS LOW TEMPERATURES AROUND 40 AND THEY ARE AROUND 30 IN THE GFS. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 615 PM CDT FRI SEP 5 2014 MVFR CLOUDS THAT POPPED UP THIS AFTERNOON...LIKELY A RESULT OF COLDER AIR SPILLING INTO THE REGION QUICKER THAN THE MOISTURE WAS EXITING...HAVE EITHER SCATTERED OUT OR RISEN TO VFR. THIS IS DUE TO EVEN DRIER AIR OVER WESTERN MN MAKING IN-ROADS INTO THE REGION. LOOK FOR THE DRIER AIR TO CONTINUE TO FLOW IN OVER THE NEXT 24 HOURS ON A 5-10 KT NORTHWEST WIND...RESULTING IN VFR CONDITIONS. THERE IS A LITTLE CONCERN FOR VALLEY FOG TONIGHT AT LSE WITH SKIES CLEARING AROUND MIDNIGHT AND TEMPERATURE/DEWPOINT SPREAD ALREADY AROUND 11 F. HOWEVER...MODEL FORECAST SOUNDINGS DEPICT PLENTY OF WIND TO KEEP THE AIR IN THE VALLEY MIXED...THUS PRECLUDING FOG OR STRATUS DEVELOPMENT. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
530 PM CDT THU SEP 4 2014 .MESOSCALE DISCUSSION... ISSUED AT 530 PM CDT THU SEP 4 2014 WATCHING SUPERCELL CLOSELY TRACKING EAST THROUGH CENTRAL TREMPEALEAU COUNTY. ITS ON THE NOSE OF 4000 MLCAPE PER SPC MESOANALYSIS PAGE...AND 0-1KM SHEAR IS 25-30 KT. APPEARS RIGHT NOW THE STORM IS NOT SURFACE BASED AS 0.5 DEGREE SRM DOES NOT SHOW MUCH ROTATION. HOWEVER...IF THAT ROTATION INCREASES...THE POTENTIAL WOULD EXIST FOR THE SUPERCELL TO DROP A TORNADO. OTHERWISE...LOOKING AHEAD INTO THE EVENING...04.20Z HRRR IS QUITE AGGRESSIVE IN DEVELOPING CONVECTION IN THE 7-9 PM WINDOW...WITH POTENTIAL SEVERE STORMS IN CENTRAL WISCONSIN. WILL KEEP A CLOSE EYE ON THIS POTENTIAL AS WELL. && .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 327 PM CDT THU SEP 4 2014 MAIN FORECAST CONCERNS ARE ON THE POTENTIAL FOR SEVERE THUNDERSTORMS. LATEST SURFACE ANALYSIS PLACED LOW PRESSURE OVER CENTRAL MINNESOTA...EDGING EAST. A COLD FRONT EXTENDED SOUTHWARD INTO WESTERN IOWA WHILE A WARM FRONT WAS POSITIONED NEAR THE INTERSTATE 94 CORRIDOR IN EAST CENTRAL MINNESOTA THROUGH WESTERN WISCONSIN. EXTENSIVE CLOUD COVER OVER MUCH OF THE FORECAST AREA WAS HELPING TO HOLD TEMPERATURES DOWN A BIT. SHOWERS AND STORMS ARE DEVELOPING ACROSS AREAS NORTH OF INTERSTATE 90 DESPITE A FAIRLY STOUT CAP IN PLACE. FORECAST SOUNDINGS ARE INDICATING 750 MB TEMPERATURES HOVERING RIGHT AROUND 15 C. SOUNDINGS SUGGEST THIS CAP WILL WEAKEN AS A SHORTWAVE APPROACHES FROM NEBRASKA/SOUTH DAKOTA THIS AFTERNOON INTO THIS EVENING JUST AS THE COLD FRONT IS MAKING ITS WAY INTO NORTHWESTERN SECTIONS OF THE FORECAST AREA. MESOSCALE MODELS ARE FIRING SHOWERS AND STORMS ALONG AND BEHIND THE FRONT THIS EVENING. IF THIS SCENARIO PLAYS OUT...THE MAIN THREATS FROM THE STORMS WOULD BE LARGE HAIL AND HEAVY RAINFALL. WE SHOULD SEE A BAND OF SHOWERS AND STORMS DEVELOP RIGHT OVER THE FORECAST AREA THIS EVENING THEN THIS BAND WILL GRADUALLY PUSH SOUTHEAST DURING THE OVERNIGHT HOURS AS THE FRONT SAGS SOUTHWARD. MUCH COOLER AIR PUSHES INTO THE FORECAST AREA IN THE WAKE OF THE FRONT TONIGHT INTO FRIDAY WITH 850 MB TEMPS GOING FROM 25 C THIS AFTERNOON TO AROUND 10 C BY FRIDAY AFTERNOON. A VERY COMFORTABLE DAY IS IN STORE FOR THE REGION ON FRIDAY AS HIGH PRESSURE BUILDS IN FROM THE WEST. PLAN PARTLY SUNNY SKIES ACROSS THE REGION WITH HIGHS RANGING FROM THE MID 60 TO LOWER 70S. .LONG TERM...(FRIDAY NIGHT THROUGH THURSDAY) ISSUED AT 327 PM CDT THU SEP 4 2014 HIGH PRESSURE REMAINS IN CONTROL FRIDAY NIGHT INTO SUNDAY AS THE REGION REMAINS IN A COOL NORTHWEST FLOW REGIME. WITH THE RIDGE AXIS NEARBY PROVIDING LIGHT AND VARIABLE WINDS FROM THE SURFACE THROUGH 2 KFT MAY SET THE STAGE FOR AREAS OF FOG LATE SATURDAY NIGHT INTO SUNDAY MORNING. HAVE INCLUDED PATCHY FOG ALONG RIVER VALLEY LOCATIONS AND OVER CENTRAL WISCONSIN DURING THIS TIMEFRAME. THE NEXT CHANCE FOR SHOWERS AND STORMS ACROSS THE REGION ARRIVES ON MONDAY AS FLOW ALOFT TURNS MORE ZONAL AND A SHORTWAVE TROUGH MOVES IN FROM THE PLAINS. TEMPERATURES WILL REMAIN SEASONABLY COOL THROUGH THE PERIOD WITH HIGHS MAINLY IN THE 70S. A MORE UNSETTLED PATTERN IS EXPECTED TO DEVELOP NEXT WEEK AND WILL REMAIN OVER THE REGION THROUGH THURSDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1230 PM CDT THU SEP 4 2014 STRONG CAP IN THE 800-700 MB LAYER WORKS ACROSS THE AREA THIS AFTERNOON INTO THE EVENING...AND LOOKS TO BE A STRONG ENOUGH INHIBITOR TO PREVENT CONVECTION. SOME MVFR CIGS CURRENTLY ASSOCIATED POST AN OUTFLOW BOUNDARY SINKING SOUTH ACROSS KRST/KLSE...MORE AMPLE COVERAGE NEAR KLSE. WITH THE INVERSION EXPECTED TO HOLD THROUGH THE AFTERNOON...THE MVFR CLOUDS COULD FOLLOW SUIT. WILL HOLD SOME MVFR CIGS THROUGH AT LEAST MID AFTERNOON - BUT COULD BE NEEDED LONGER. MESO MODELS PROVIDING A VARIETY OF SOLUTIONS ON WHERE/WHEN CONVECTION COULD REFIRE THIS AFTERNOON AND EVENING. CONFIDENCE LOWER AS A RESULT. THAT SAID...GOING TO PUT FAITH IN THE STRONG LOW LEVEL WARMING/CAP WHICH WILL NEED AN APPROACHING COLD FRONT TO THE WEST TO PROVIDE A SHOWER/STORM THREAT. SOMEWHERE IN THE 02-04Z TIME FRAME LOOKS TO BE THE MOST FAVORABLE TIME FOR PRECIPITATION. ANTICIPATE CHANGES TO THE FORECAST AS THE CONVECTIVE TIMING/COVERAGE BECOMES CLEARER. CLOUDS LIKELY TO HANG AROUND POST FRONT THROUGH FRI MORNING...BUT APPEAR TO BE THE MID/UPPER LEVEL VARIETY. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ MESOSCALE...AJ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
210 PM CDT THU SEP 4 2014 .UPDATED... ISSUED AT 210 PM CDT THU SEP 4 2014 SHOWERS/STORMS QUICKLY DEVELOPING ACROSS PARTS OF THE REGION...MOSTLY NORTH OF I-90. DESPITE A STRONG 800-700 MB CAP WITH 16-18 C TEMPS...PREVIOUS OUTFLOW BOUNDARY/WARM FRONT MIX...COUPLED WITH PUSH OF SLOPING LOW LEVEL MOISTURE TRANSPORT INTO ELEVATED INSTABILITY...HAS KICKED OFF THE CONVECTION. RAP13 SUGGESTS THIS ACTIVITY WILL CONTINUE TO EXPAND AND PUSH EASTWARD FOR THE REST OF THE AFTERNOON. THERE COULD BE A FEW STRONGER STORMS...ALTHOUGH SEVERE WEATHER IS NOT ANTICIPATED AT THIS TIME. THERE STILL APPEARS TO BE A THREAT FOR STRONG-SEVERE STORMS AROUND MID EVENING...AS A COLD FRONT WORKS IN FROM THE WEST. MOST OF THIS ACTIVITY APPEARS TO BE POST FRONTAL...BUT WILL STILL HAVE DECENT INSTABILITY AND SOME WIND SHEAR TO TAP INTO. .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 326 AM CDT THU SEP 4 2014 SURFACE MAP AS OF 3 AM THIS MORNING HAD A DEEP 996MB LOW OVER EASTERN SD WITH A WARM FRONT EXTENDING ACROSS SOUTHERN MN AND INTO SOUTHWEST WI. CURRENTLY WATCHING ONE CLUSTER OF STRONG THUNDERSTORMS DEPARTING THE AREA INTO NORTHEAST WI. WITHIN THE LAST 1/2 HOUR...A CLUSTER OF SHOWERS AND THUNDERSTORMS POPPED UP OVER FAR NORTHEAST IA/SOUTHWEST WI. FURTHER ANALYSIS SHOWING THESE SHOWERS AND STORMS FORMING IN RESPONSE TO A NOSE OF STRONG 850MB MOISTURE TRANSPORT WORKING NORTHEAST ACROSS IA...AND OCCURRING ABOVE A VERY STRONG 700- 750MB CAP OF 14C PER THE RAP BUFKIT AT BLUE RIVER WI. OTHERWISE... TEMPERATURES ACROSS THE AREA EARLY THIS MORNING WERE IN THE 60S ACROSS NORTH CENTRAL WI...AND IN THE 70S ELSEWHERE ACROSS THE ARX FORECAST AREA. WARM FRONT MAKES A PUSH NORTHEAST THROUGH THE REST OF THE AREA THIS MORNING. THINKING THOSE SHOWERS/STORMS WILL SHOVE OUT OF THE AREA AS CAP STRENGTHENS IN WARM SECTOR. WILL BE WATCHING AN MCS OVER ND MAKING ITS WAY EAST-SOUTHEAST...WHICH COULD CLIP CLARK AND TAYLOR COUNTIES AS IT MAKES ITS WAY ACROSS FAR NORTHERN WI/UPPER MI. MAY HAVE TO ADJUST POPS ACCORDINGLY. OTHERWISE...STRONG WARM AIR ADVECTION WILL TAKE PLACE ACROSS THE AREA WITH STRENGTHENING 700-750MB CAP. THIS SHOULD HOLD OFF ANY FURTHER CONVECTION AND PUSH TEMPERATURES WELL INTO THE 80S...TO A FEW LOWER 90S ALONG/SOUTH OF I-90. DEW POINTS WILL ALSO BE INCREASING INTO THE LOWER 70S THROUGH THE DAY...PRODUCING VERY WARM/MUGGY/UNCOMFORTABLE CONDITIONS. HEAT INDICES FOR THE MOST PART LOOK TO BE IN THE 90-100 RANGE...BUT COULD SEE A FEW HOURS OF 100- 105 IN A FEW SPOTS IN THE MISSISSIPPI/WISCONSIN RIVER VALLEYS. NOT THINKING A HEAT ADVISORY WILL BE NEEDED AT THIS POINT DUE TO THE BRIEF TOUCH IN THE CRITERIA RANGE. WILL HIT IT HARD WITH OUR OTHER PRODUCTS. CAP HOLDS STRONG INTO THE AFTERNOON HOURS AS A COLD FRONT PUSHES SOUTHEASTWARD INTO NORTHERN WI/SOUTH CENTRAL MN. MODELS AT ODDS AT HANDLING CONVECTION OR LACK THEREOF WHICH HEDGES ON STRENGTH OF CAP...WHICH IS VERY STRONG FOR THIS TIME OF YEAR. GFS/ECMWF/CANADIAN DETERMINISTIC MODELS ALL HOLD OFF DEVELOPING CONVECTION THROUGH 7PM. NAM IS A BIT MORE GUNG-HO FIRING ALONG THE FRONT BASICALLY NORTH OF I-94 BETWEEN 4-7PM. NMM/ARW WRF MODELS SIDE WITH THE NAM. REASON BEING... BUFKIT SOUNDINGS REVEAL POSSIBLY SOME ELEVATED CONVECTION BURBLING ABOVE THE CAP AS MID-LEVEL COOLING/STEEPENING LAPSE RATES TAKE PLACE WITH INCOMING MID-LEVEL TROUGH. THIS WOULD COMPROMISE THE CAP AND LET SURFACE BASED/DEEP CONVECTION RELEASE ALONG THE FRONT. WILL HAVE TO KEEP AN EYE ON THIS FOR SEVERE WIND/HAIL POTENTIAL AS 0- 3KM BULK SHEAR IS PLENTIFUL IN THE 30-40KT RANGE ALONG WITH MUCAPE IN THE 3000-4000J/KG RANGE. THE COLD FRONT CONTINUES TO PUSH SOUTHEAST THROUGH THE AREA FRIDAY NIGHT FOR CONTINUED THUNDERSTORM CHANCES. SOME OF THESE STORMS COULD BE REMAIN SEVERE AT LEAST INTO THE EVENING HOURS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 326 AM CDT THU SEP 4 2014 WITH THE COLD FRONT PUSHED INTO NORTHERN IL BY FRIDAY MORNING... NORTHWEST WINDS WILL DRAW DRIER/COOLER AIR OVER THE FORECAST AREA. EXPECTING FAIRLY BREEZY NORTHWEST WINDS IN THE 15-25MPH RANGE WITH HIGHS ONLY TOPPING OFF IN THE UPPER 60S TO TO LOWER 70S. MORE EARLY FALL-LIKE CONDITIONS ARE THEN EXPECTED INTO THE WEEKEND AS CANADIAN HIGH PRESSURE DOMINATES THE CENTRAL CONUS/UPPER MISSISSIPPI RIVER VALLEY REGIONS. LOOK FOR MOSTLY CLEAR SKIES THROUGH SUNDAY WITH HIGHS SATURDAY AND SUNDAY IN THE 70S AND OVERNIGHT LOWS IN THE 40S TO LOWER 50S. FOR MONDAY THROUGH WEDNESDAY...DEEPENING CYCLONIC FLOW OVER CANADA AND NORTHERN CONUS WILL DRIVE A COUPLE TROUGHS THROUGH THE REGION FOR A PERIOD OF UNSETTLED WEATHER WITH ON/OFF SHOWER AND THUNDERSTORM CHANCES. TEMPERATURES ARE EXPECTED TO BE AT OR A FEW DEGREES BELOW NORMAL WITH HIGHS IN THE 70S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1230 PM CDT THU SEP 4 2014 STRONG CAP IN THE 800-700 MB LAYER WORKS ACROSS THE AREA THIS AFTERNOON INTO THE EVENING...AND LOOKS TO BE A STRONG ENOUGH INHIBITOR TO PREVENT CONVECTION. SOME MVFR CIGS CURRENTLY ASSOCIATED POST AN OUTFLOW BOUNDARY SINKING SOUTH ACROSS KRST/KLSE...MORE AMPLE COVERAGE NEAR KLSE. WITH THE INVERSION EXPECTED TO HOLD THROUGH THE AFTERNOON...THE MVFR CLOUDS COULD FOLLOW SUIT. WILL HOLD SOME MVFR CIGS THROUGH AT LEAST MID AFTERNOON - BUT COULD BE NEEDED LONGER. MESO MODELS PROVIDING A VARIETY OF SOLUTIONS ON WHERE/WHEN CONVECTION COULD REFIRE THIS AFTERNOON AND EVENING. CONFIDENCE LOWER AS A RESULT. THAT SAID...GOING TO PUT FAITH IN THE STRONG LOW LEVEL WARMING/CAP WHICH WILL NEED AN APPROACHING COLD FRONT TO THE WEST TO PROVIDE A SHOWER/STORM THREAT. SOMEWHERE IN THE 02-04Z TIME FRAME LOOKS TO BE THE MOST FAVORABLE TIME FOR PRECIPITATION. ANTICIPATE CHANGES TO THE FORECAST AS THE CONVECTIVE TIMING/COVERAGE BECOMES CLEARER. CLOUDS LIKELY TO HANG AROUND POST FRONT THROUGH FRI MORNING...BUT APPEAR TO BE THE MID/UPPER LEVEL VARIETY. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATED.....RIECK SHORT TERM...DAS LONG TERM....DAS AVIATION.....RIECK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1230 PM CDT THU SEP 4 2014 .UPDATED... ISSUED AT 1230 PM CDT THU SEP 4 2014 STRONG LOW LEVEL CAP PROGGED TO BUILD ACROSS THE FORECAST AREA THIS AFTERNOON...WITH 800-700 MB RAP LAYER TEMPS OF 16-18 C. MULTIPLE OUTFLOW BOUNDARIES TO WATCH THROUGH THE AFTERNOON THOUGH...ONE OF WHICH IS PROVIDING MORE LOW CLOUDS ACROSS WESTERN WI THEN PREVIOUSLY THOUGHT. WITH STRONG INVERSION...THESE COULD STICK AROUND THROUGH THE AFTERNOON. MEANWHILE A BOUNDARY ACROSS IA/NORTHERN IL HAS FIRED SHOWERS/STORMS LATE IN THE MORNING...WITH THE MESO MODELS KEEPING THIS ACTIVITY JUST SOUTH OF THE FORECAST AREA. FURTHER NORTH...SCATTERED SHOWERS AND A FEW THUNDERSTORMS SHOULD CONTINUE TO SPARK ACROSS AN OUTFLOW/WARM FRONTAL BOUNDARY...CURRENTLY LAYING UP FROM CENTRAL MN INTO NORTHERN WI. TRENDS HERE FAVOR KEEPING THE BULK OF ANY PCPN THREAT NORTH OF HIGHWAY 10 IN NORTHCENTRAL WI. OVERALL...THE SCENARIO FAVORS DRY CONDITIONS THROUGH THE BETTER PART OF THE AFTERNOON. AS THE FRONT APPROACHES FROM WEST THIS EVENING...THE THREAT WILL INCREASE WITH SHOWER/STORMS DEVELOPING-CONTINUING ABOVE THE CAP...MOSTLY POST FRONTAL. THIS WOULD PLACE OUR HIGHER THREAT FOR STORMS IN THE MID EVENING HOURS. THERE WOULD BE A STRONG-SEVERE THREAT WITH THE STORMS...ALTHOUGH THAT APPEARS MORE ISOLATED IN NATURE. .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 326 AM CDT THU SEP 4 2014 SURFACE MAP AS OF 3 AM THIS MORNING HAD A DEEP 996MB LOW OVER EASTERN SD WITH A WARM FRONT EXTENDING ACROSS SOUTHERN MN AND INTO SOUTHWEST WI. CURRENTLY WATCHING ONE CLUSTER OF STRONG THUNDERSTORMS DEPARTING THE AREA INTO NORTHEAST WI. WITHIN THE LAST 1/2 HOUR...A CLUSTER OF SHOWERS AND THUNDERSTORMS POPPED UP OVER FAR NORTHEAST IA/SOUTHWEST WI. FURTHER ANALYSIS SHOWING THESE SHOWERS AND STORMS FORMING IN RESPONSE TO A NOSE OF STRONG 850MB MOISTURE TRANSPORT WORKING NORTHEAST ACROSS IA...AND OCCURRING ABOVE A VERY STRONG 700- 750MB CAP OF 14C PER THE RAP BUFKIT AT BLUE RIVER WI. OTHERWISE... TEMPERATURES ACROSS THE AREA EARLY THIS MORNING WERE IN THE 60S ACROSS NORTH CENTRAL WI...AND IN THE 70S ELSEWHERE ACROSS THE ARX FORECAST AREA. WARM FRONT MAKES A PUSH NORTHEAST THROUGH THE REST OF THE AREA THIS MORNING. THINKING THOSE SHOWERS/STORMS WILL SHOVE OUT OF THE AREA AS CAP STRENGTHENS IN WARM SECTOR. WILL BE WATCHING AN MCS OVER ND MAKING ITS WAY EAST-SOUTHEAST...WHICH COULD CLIP CLARK AND TAYLOR COUNTIES AS IT MAKES ITS WAY ACROSS FAR NORTHERN WI/UPPER MI. MAY HAVE TO ADJUST POPS ACCORDINGLY. OTHERWISE...STRONG WARM AIR ADVECTION WILL TAKE PLACE ACROSS THE AREA WITH STRENGTHENING 700-750MB CAP. THIS SHOULD HOLD OFF ANY FURTHER CONVECTION AND PUSH TEMPERATURES WELL INTO THE 80S...TO A FEW LOWER 90S ALONG/SOUTH OF I-90. DEW POINTS WILL ALSO BE INCREASING INTO THE LOWER 70S THROUGH THE DAY...PRODUCING VERY WARM/MUGGY/UNCOMFORTABLE CONDITIONS. HEAT INDICES FOR THE MOST PART LOOK TO BE IN THE 90-100 RANGE...BUT COULD SEE A FEW HOURS OF 100- 105 IN A FEW SPOTS IN THE MISSISSIPPI/WISCONSIN RIVER VALLEYS. NOT THINKING A HEAT ADVISORY WILL BE NEEDED AT THIS POINT DUE TO THE BRIEF TOUCH IN THE CRITERIA RANGE. WILL HIT IT HARD WITH OUR OTHER PRODUCTS. CAP HOLDS STRONG INTO THE AFTERNOON HOURS AS A COLD FRONT PUSHES SOUTHEASTWARD INTO NORTHERN WI/SOUTH CENTRAL MN. MODELS AT ODDS AT HANDLING CONVECTION OR LACK THEREOF WHICH HEDGES ON STRENGTH OF CAP...WHICH IS VERY STRONG FOR THIS TIME OF YEAR. GFS/ECMWF/CANADIAN DETERMINISTIC MODELS ALL HOLD OFF DEVELOPING CONVECTION THROUGH 7PM. NAM IS A BIT MORE GUNG-HO FIRING ALONG THE FRONT BASICALLY NORTH OF I-94 BETWEEN 4-7PM. NMM/ARW WRF MODELS SIDE WITH THE NAM. REASON BEING... BUFKIT SOUNDINGS REVEAL POSSIBLY SOME ELEVATED CONVECTION BURBLING ABOVE THE CAP AS MID-LEVEL COOLING/STEEPENING LAPSE RATES TAKE PLACE WITH INCOMING MID-LEVEL TROUGH. THIS WOULD COMPROMISE THE CAP AND LET SURFACE BASED/DEEP CONVECTION RELEASE ALONG THE FRONT. WILL HAVE TO KEEP AN EYE ON THIS FOR SEVERE WIND/HAIL POTENTIAL AS 0- 3KM BULK SHEAR IS PLENTIFUL IN THE 30-40KT RANGE ALONG WITH MUCAPE IN THE 3000-4000J/KG RANGE. THE COLD FRONT CONTINUES TO PUSH SOUTHEAST THROUGH THE AREA FRIDAY NIGHT FOR CONTINUED THUNDERSTORM CHANCES. SOME OF THESE STORMS COULD BE REMAIN SEVERE AT LEAST INTO THE EVENING HOURS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 326 AM CDT THU SEP 4 2014 WITH THE COLD FRONT PUSHED INTO NORTHERN IL BY FRIDAY MORNING... NORTHWEST WINDS WILL DRAW DRIER/COOLER AIR OVER THE FORECAST AREA. EXPECTING FAIRLY BREEZY NORTHWEST WINDS IN THE 15-25MPH RANGE WITH HIGHS ONLY TOPPING OFF IN THE UPPER 60S TO TO LOWER 70S. MORE EARLY FALL-LIKE CONDITIONS ARE THEN EXPECTED INTO THE WEEKEND AS CANADIAN HIGH PRESSURE DOMINATES THE CENTRAL CONUS/UPPER MISSISSIPPI RIVER VALLEY REGIONS. LOOK FOR MOSTLY CLEAR SKIES THROUGH SUNDAY WITH HIGHS SATURDAY AND SUNDAY IN THE 70S AND OVERNIGHT LOWS IN THE 40S TO LOWER 50S. FOR MONDAY THROUGH WEDNESDAY...DEEPENING CYCLONIC FLOW OVER CANADA AND NORTHERN CONUS WILL DRIVE A COUPLE TROUGHS THROUGH THE REGION FOR A PERIOD OF UNSETTLED WEATHER WITH ON/OFF SHOWER AND THUNDERSTORM CHANCES. TEMPERATURES ARE EXPECTED TO BE AT OR A FEW DEGREES BELOW NORMAL WITH HIGHS IN THE 70S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1230 PM CDT THU SEP 4 2014 STRONG CAP IN THE 800-700 MB LAYER WORKS ACROSS THE AREA THIS AFTERNOON INTO THE EVENING...AND LOOKS TO BE A STRONG ENOUGH INHIBITOR TO PREVENT CONVECTION. SOME MVFR CIGS CURRENTLY ASSOCIATED POST AN OUTFLOW BOUNDARY SINKING SOUTH ACROSS KRST/KLSE...MORE AMPLE COVERAGE NEAR KLSE. WITH THE INVERSION EXPECTED TO HOLD THROUGH THE AFTERNOON...THE MVFR CLOUDS COULD FOLLOW SUIT. WILL HOLD SOME MVFR CIGS THROUGH AT LEAST MID AFTERNOON - BUT COULD BE NEEDED LONGER. MESO MODELS PROVIDING A VARIETY OF SOLUTIONS ON WHERE/WHEN CONVECTION COULD REFIRE THIS AFTERNOON AND EVENING. CONFIDENCE LOWER AS A RESULT. THAT SAID...GOING TO PUT FAITH IN THE STRONG LOW LEVEL WARMING/CAP WHICH WILL NEED AN APPROACHING COLD FRONT TO THE WEST TO PROVIDE A SHOWER/STORM THREAT. SOMEWHERE IN THE 02-04Z TIME FRAME LOOKS TO BE THE MOST FAVORABLE TIME FOR PRECIPITATION. ANTICIPATE CHANGES TO THE FORECAST AS THE CONVECTIVE TIMING/COVERAGE BECOMES CLEARER. CLOUDS LIKELY TO HANG AROUND POST FRONT THROUGH FRI MORNING...BUT APPEAR TO BE THE MID/UPPER LEVEL VARIETY. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATED.....RIECK SHORT TERM...DAS LONG TERM....DAS AVIATION.....RIECK
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
959 AM CDT THU SEP 4 2014 .UPDATE... SHOWERS CONTINUE TO DIMINISH ACROSS SOUTHERN WISCONSIN THIS MORNING. LATEST MESOSCALE MODELS CONTINUE TO SHOW THAT A CAPPED ENVIRONMENT SHOULD RESULT IN DRY CONDITIONS FROM LATE MORNING THROUGH THE AFTERNOON. ALSO...STILL THINK THAT THERE SHOULD BE SOME SUNSHINE...WITH CLEARING ALREADY OCCURING IN THE LONE ROCK AND WISCONSIN DELLS AREAS. MODELS ARE STILL SHOWING 925 MB TEMPS IN THE 25-27C RANGE BY LATE AFTERNOON. GIVEN ENOUGH SUN...MOST PLACES SHOULD APPROACH OR REACH 90 BY THE END OF THE DAY...SO WILL LEAVE TEMPS AS IS FOR NOW. STILL A LOT TO LOOK AT TO EVALUATE THE THUNDERSTORM POTENTIAL FOR THIS EVENING AND OVERNIGHT. HOPEFULLY THE PICTURE WILL BECOME MORE CLEAR AS 12Z MODELS ROLL IN. && .AVIATION/18Z TAFS/... SHOWERS CONTINUE TO DIMINISH ACROSS SOUTHERN WISCONSIN THIS MORNING WITH DRY WEATHER EXPECTED FROM LATE MORNING THROUGH THE AFTERNOON. STILL LOOKS A CHANCE FOR STORMS THIS EVENING AND OVERNIGHT...THOUGH MODELS ARE NOT IN VERY GOOD AGREEMENT WITH THE TIMING/PLACEMENT OF CONVECTION. HOPEFULLY THE PICTURE WILL BECOME MORE CLEAR AS 12Z MODELS ROLL IN. LOOKS LIKE SOME MORE LOW LEVEL WIND SHEAR IS POSSIBLE THIS EVENING INTO TONIGHT AS WINDS EASE A BIT AT THE SURFACE AND THE LOW LEVEL JET SITS OVERHEAD. OTHER THAN LOWER VSBYS IN MODERATE TO HEAVY RAIN...EXPECT VFR CONDITIONS TO CONTINUE THROUGH FRIDAY. && .PREV DISCUSSION... /ISSUED 228 AM CDT THU SEP 4 2014/ SHORT TERM... TODAY...FORECAST CONFIDENCE IS MEDIUM. THE SECONDARY CONVECTIVE DEVELOPMENT...TIED WITH THE H8 WARM FRONT ON THE NOSE OF THE LOW LEVEL JET LEANING INTO THE AREA...IS EXPANDING QUICKLY ACROSS SOUTHWEST WI AT THE TIME OF THIS WRITING. FOR SOME REASON THE HRRR HAS DECIDED TO DUMP THIS DEVELOPMENT AND WENT DRY WITH THE 04 AND 05Z UPDATES. WELL...THAT/S NOT GOING TO WORK OUT. SATELLITE IMAGERY IS SHOWING A LOWER MID DECK EXPANDING QUICKLY UPSTREAM...HIGHLIGHTING THE CONVERGENCE OF WARM AND MOIST AIR ON THE NOSE OF THAT H8 JET. MOST OF THE MODELS SHOW THIS DEVELOPMENT OCCURRING EARLY THIS MORNING...EXITING BY MID TO LATE MORNING. ISOLATED SEVERE STORMS ARE POSSIBLE WITH WIND AND HAIL THE MAIN THREAT. THE RAIN WOULD BE HEAVY AND URBAN AND SMALL STREAM FLOODING IS POSIBLE IF ANY STORMS TURN AWAY FROM THE FASTER MEAN FLOW. ONCE THE STORMS MOVE OUT...WE GET INTO A VERY IMPRESSIVE THERMAL RIDGE AHEAD OF AN APPROACHING COLD FRONT. 925MB TEMPS CLIMB TO AN IMPRESSIVE 25-27C...IF WE GET ENOUGH SUNSHINE WE COULD SEE MANY AREAS HIT THE 90 MARK. I/M COMFORTABLE KEEPING WHAT WE HAVE IN THE FORECAST...WHICH IS ABOVE MOST GUIDANCE VALUES RIGHT NOW. THE AIRMASS OVER US TODAY WILL BE VERY HUMID WITH DEW POINTS REACHING THE LOWER 70S. THE HEAT INDEX WILL BE IN THE MID TO UPPER 90S. THANKFULLY THIS IS SHORT LIVED AS THE COLD FRONT COMING THROUGH TONIGHT WILL BRING MUCH COOLER TEMPS ON FRIDAY. TONIGHT...FORECAST CONFIDENCE IS MEDIUM. A STRONG COLD FRONT WILL PUSH THROUGH THE AREA OVERNIGHT. IT/S A RATHER LATE SHOW FOR SOUTHERN WISCONSIN AS THE FRONT DOESN/T REACH MADISON UNTIL ABOUT 6 AM FRIDAY AND MILWAUKEE ABOUT 9 AM. THE INITIAL DEVELOPMENT SHOULD OCCUR OVER ECNTRL MN AND WCNTRL WI THEN EXPAND AND ORGANIZE ALONG THE FRONT WITH TIME...HEADING SOUTHEAST INTO SOUTHERN WISCONSIN OVERNIGHT. THE AIRMASS WILL BE VERY MOIST AHEAD OF THE FRONT...BUT THE LATE TIMING WILL BEGIN TO LIMIT INSTABILITY OVER TIME. IN ADDITION...THE LOW LEVEL JET FOCUSES WELL EAST OF WISCONSIN BY THE TIME THE FRONT ARRIVES. WOULD EXPECT A FEW STORMS TO BECOME SEVERE NORTHWEST OF OUR FORECAST AREA...WHERE STORMS INTITIATE...THEN AS THEY DRIFT SOUTH INTO THE FORECAST AREA...THE INTENSITY WILL GRADUALLY DIMINISH. SPC HAS US IN A SLIGHT RISK OF SEVERE STORMS NORTH OF A PORT WASHINGTON TO MADISON TO DODGEVILLE LINE. THE FAR SOUTH WOULD STRUGGLE TO SEE SEVERE GIVEN THE TIMING. THIS LOOKS VERY REASONABLE. THE MAIN THREAT WILL BE WIND AND HAIL. FRIDAY AND FRIDAY NIGHT...FORECAST CONFIDENCE MEDIUM. THE SURFACE TO 850MB COLD FRONT WILL BE REACHING FAR SOUTHEAST WI AROUND 12Z...WHICH IS LATER THAN THE PAST SEVERAL MODEL RUNS. MEANWHILE... A STRONG MID LEVEL SHORTWAVE TROUGH WILL BE SLIDING ACROSS THE UPPER MIDWEST. AHEAD OF THIS TROUGH... THERE WILL BE WEAK SHORTWAVE ACTIVITY AND ALSO RISING MOTION IN THE RIGHT ENTRANCE REGION OF AN UPPER JET. THE AREA JUST BEHIND THE SURFACE COLD FRONT AND AHEAD OF THE UPPER TROUGH WILL LINE UP OVER SOUTHEAST WI DURING THE DAY FRIDAY AND KEEP THE POSSIBILITY OF SHOWERS AND ISOLATED THUNDERSTORMS GOING. THE LIMITING FACTOR FOR PRECIP IS A DRY LAYER FROM 5 TO 10 KFT. THE MODELS ARE MIXED ABOUT WHERE SHOWERS AND THUNDERSTORMS WILL TRACK FRIDAY AFTERNOON. MOST SUGGEST THE MAIN FORCING AND PRECIP WILL BE SOUTH OF THE WI/IL BORDER. THUS...WILL CONTINUE THE DIMINISHING TREND FOR POPS ON FRIDAY AFTERNOON AND EVENING. THERE SHOULD BE PLENTY OF CLOUDS OVER SOUTHERN WI ON FRIDAY. THAT AND THE COLD AIR ADVECTION WILL LIMIT HIGHS TO THE MID 70S. THE MID LEVEL SHORTWAVE TROUGH WILL EXIT SOUTHEAST WI BY AROUND MIDNIGHT FRIDAY NIGHT. THIS WILL USHER MUCH DRIER AND COOLER AIR INTO SOUTHERN WI WHICH WILL HANG AROUND THROUGH THE WHOLE WEEKEND AND MONDAY. LONG TERM... SATURDAY THROUGH MONDAY...FORECAST CONFIDENCE HIGH. PLAN ON A QUIET STRETCH OF WEATHER FOR THE WEEKEND WITH LOW HUMIDITY AND COOLER TEMPERATURES. HIGHS WILL BE IN THE LOWER TO MID 70S WITH PLENTY OF SUNSHINE. LOWS WILL DROP DOWN INTO THE LOWER 50S...WITH SATURDAY NIGHT LOOKING LIKE THE COOLEST. DEWPOINT DEPRESSIONS SHOULD BE FAIRLY LOW WITH LIGHT WINDS...SO PATCHY FOG LOOKS POSSIBLE. MONDAY NIGHT THROUGH THURSDAY...FORECAST CONFIDENCE MEDIUM. THE ECMWF AND GFS ARE NOW OUT OF PHASE FOR THE NEXT WARM AIR ROUND OF THUNDERSTORMS IMPACTING SOUTHERN WI MONDAY NIGHT AND TUESDAY. THE GFS IS ROUGHLY 6 HOURS SLOWER WITH THE PRECIP AND HAS A WEAKER- LOOKING SHORTWAVE TROUGH DUE TO THE EARLIER ARRIVAL OF AN UPPER JET STREAK. THEN THE TWO MODELS ARE BACK INTO GENERAL AGREEMENT ABOUT A BACK DOOR COLD FRONT DROPPING DOWN THE LAKE INTO SOUTHERN WI LATE TUESDAY NIGHT. THERE IS NOT MUCH FORCING FOR PRECIP...SO LOW CLOUDS AND MAYBE A FEW SPRINKLES WOULD BE POSSIBLE THROUGH WED MORNING. THEN THERE SHOULD BE A PERIOD OF QUIET WEATHER WITH EASTERLY WINDS OVER SOUTHERN WI THROUGH WED NIGHT. THEREFORE...WENT WITH A LOWERING TREND FOR POPS AND THUNDER IN THE FORECAST. ANOTHER ROUND OF SHOWERS AND STORMS ARE POSSIBLE FOR SOUTHERN WI AS A MID LEVEL TROUGH SLIDES FROM THE NORTHERN PLAINS TO THE GREAT LAKES REGION LATE IN THE WEEK...THURSDAY THROUGH FRIDAY NIGHT. THERE ARE STILL PLENTY OF MODEL DIFFERENCES THAT WILL NEED TO BE IRONED OUT BEFORE DECIDING THE EXTENT OF THUNDER. AVIATION/12Z TAFS/... IN GENERAL...EXPECT VFR CONDITIONS THROUGH THE TAF PERIOD. HOWEVER...THERE ARE A COUPLE OF OPPORTUNITIES FOR LOWER CONDITIONS. WE SHOULD SEE AT LEAST SCATTERED CONVECTION THIS MORNING AS A WARM FRONT MOVES THROUGH. CONDITIONS WOULD DETERIORATE TO MVFR OR EVEN IFR LEVELS IN ANY STRONGER STORMS. THINGS SHOULD CLEAR OUT BY LATE MORNING AS HOT AIR ARRIVES AHEAD OF AN APPROACHING COLD FRONT. LOOK FOR RATHER BREEZY CONDITIONS WITH A SOUTH TO SOUTHWEST WIND LATER THIS MORNING AND AFTERNOON. THE COLD FRONT ARRIVES LATE TONIGHT...REACHING MADISON AROUND 12Z FRIDAY AND KMKE/KUES/KENW AROUND 15-16Z FRI. IT LOOKS LIKE THERE COULD BE A SHORT PERIOD OF MVFR CIGS/VSBYS IN THE COLD AIR ADVECTION IN THE IMMEDIATE WAKE OF THE FRONT. THUNDERSTORMS ARE ALSO POSSIBLE WITH THE FRONTAL PASSAGE LATE TONIGHT. MARINE... SOUTH TO SOUTHWEST WINDS TODAY WILL GUST TO AROUND 25 KNOTS...SO A SMALL CRAFT ADVISORY IS IN EFFECT FROM 10 AM TO 10 PM TODAY. WAVES WILL INCREASE TO 3 TO 5 FEET THURSDAY...THE HIGHEST WAVES IN THE NORTH. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LMZ643>646. && $$ TODAY/TONIGHT AND AVIATION/MARINE...DAVIS FRIDAY THROUGH WEDNESDAY...MRC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
608 AM CDT THU SEP 4 2014 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 326 AM CDT THU SEP 4 2014 SURFACE MAP AS OF 3 AM THIS MORNING HAD A DEEP 996MB LOW OVER EASTERN SD WITH A WARM FRONT EXTENDING ACROSS SOUTHERN MN AND INTO SOUTHWEST WI. CURRENTLY WATCHING ONE CLUSTER OF STRONG THUNDERSTORMS DEPARTING THE AREA INTO NORTHEAST WI. WITHIN THE LAST 1/2 HOUR...A CLUSTER OF SHOWERS AND THUNDERSTORMS POPPED UP OVER FAR NORTHEAST IA/SOUTHWEST WI. FURTHER ANALYSIS SHOWING THESE SHOWERS AND STORMS FORMING IN RESPONSE TO A NOSE OF STRONG 850MB MOISTURE TRANSPORT WORKING NORTHEAST ACROSS IA...AND OCCURRING ABOVE A VERY STRONG 700- 750MB CAP OF 14C PER THE RAP BUFKIT AT BLUE RIVER WI. OTHERWISE... TEMPERATURES ACROSS THE AREA EARLY THIS MORNING WERE IN THE 60S ACROSS NORTH CENTRAL WI...AND IN THE 70S ELSEWHERE ACROSS THE ARX FORECAST AREA. WARM FRONT MAKES A PUSH NORTHEAST THROUGH THE REST OF THE AREA THIS MORNING. THINKING THOSE SHOWERS/STORMS WILL SHOVE OUT OF THE AREA AS CAP STRENGTHENS IN WARM SECTOR. WILL BE WATCHING AN MCS OVER ND MAKING ITS WAY EAST-SOUTHEAST...WHICH COULD CLIP CLARK AND TAYLOR COUNTIES AS IT MAKES ITS WAY ACROSS FAR NORTHERN WI/UPPER MI. MAY HAVE TO ADJUST POPS ACCORDINGLY. OTHERWISE...STRONG WARM AIR ADVECTION WILL TAKE PLACE ACROSS THE AREA WITH STRENGTHENING 700-750MB CAP. THIS SHOULD HOLD OFF ANY FURTHER CONVECTION AND PUSH TEMPERATURES WELL INTO THE 80S...TO A FEW LOWER 90S ALONG/SOUTH OF I-90. DEW POINTS WILL ALSO BE INCREASING INTO THE LOWER 70S THROUGH THE DAY...PRODUCING VERY WARM/MUGGY/UNCOMFORTABLE CONDITIONS. HEAT INDICES FOR THE MOST PART LOOK TO BE IN THE 90-100 RANGE...BUT COULD SEE A FEW HOURS OF 100- 105 IN A FEW SPOTS IN THE MISSISSIPPI/WISCONSIN RIVER VALLEYS. NOT THINKING A HEAT ADVISORY WILL BE NEEDED AT THIS POINT DUE TO THE BRIEF TOUCH IN THE CRITERIA RANGE. WILL HIT IT HARD WITH OUR OTHER PRODUCTS. CAP HOLDS STRONG INTO THE AFTERNOON HOURS AS A COLD FRONT PUSHES SOUTHEASTWARD INTO NORTHERN WI/SOUTH CENTRAL MN. MODELS AT ODDS AT HANDLING CONVECTION OR LACK THEREOF WHICH HEDGES ON STRENGTH OF CAP...WHICH IS VERY STRONG FOR THIS TIME OF YEAR. GFS/ECMWF/CANADIAN DETERMINISTIC MODELS ALL HOLD OFF DEVELOPING CONVECTION THROUGH 7PM. NAM IS A BIT MORE GUNG-HO FIRING ALONG THE FRONT BASICALLY NORTH OF I-94 BETWEEN 4-7PM. NMM/ARW WRF MODELS SIDE WITH THE NAM. REASON BEING... BUFKIT SOUNDINGS REVEAL POSSIBLY SOME ELEVATED CONVECTION BURBLING ABOVE THE CAP AS MID-LEVEL COOLING/STEEPENING LAPSE RATES TAKE PLACE WITH INCOMING MID-LEVEL TROUGH. THIS WOULD COMPROMISE THE CAP AND LET SURFACE BASED/DEEP CONVECTION RELEASE ALONG THE FRONT. WILL HAVE TO KEEP AN EYE ON THIS FOR SEVERE WIND/HAIL POTENTIAL AS 0- 3KM BULK SHEAR IS PLENTIFUL IN THE 30-40KT RANGE ALONG WITH MUCAPE IN THE 3000-4000J/KG RANGE. THE COLD FRONT CONTINUES TO PUSH SOUTHEAST THROUGH THE AREA FRIDAY NIGHT FOR CONTINUED THUNDERSTORM CHANCES. SOME OF THESE STORMS COULD BE REMAIN SEVERE AT LEAST INTO THE EVENING HOURS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 326 AM CDT THU SEP 4 2014 WITH THE COLD FRONT PUSHED INTO NORTHERN IL BY FRIDAY MORNING... NORTHWEST WINDS WILL DRAW DRIER/COOLER AIR OVER THE FORECAST AREA. EXPECTING FAIRLY BREEZY NORTHWEST WINDS IN THE 15-25MPH RANGE WITH HIGHS ONLY TOPPING OFF IN THE UPPER 60S TO TO LOWER 70S. MORE EARLY FALL-LIKE CONDITIONS ARE THEN EXPECTED INTO THE WEEKEND AS CANADIAN HIGH PRESSURE DOMINATES THE CENTRAL CONUS/UPPER MISSISSIPPI RIVER VALLEY REGIONS. LOOK FOR MOSTLY CLEAR SKIES THROUGH SUNDAY WITH HIGHS SATURDAY AND SUNDAY IN THE 70S AND OVERNIGHT LOWS IN THE 40S TO LOWER 50S. FOR MONDAY THROUGH WEDNESDAY...DEEPENING CYCLONIC FLOW OVER CANADA AND NORTHERN CONUS WILL DRIVE A COUPLE TROUGHS THROUGH THE REGION FOR A PERIOD OF UNSETTLED WEATHER WITH ON/OFF SHOWER AND THUNDERSTORM CHANCES. TEMPERATURES ARE EXPECTED TO BE AT OR A FEW DEGREES BELOW NORMAL WITH HIGHS IN THE 70S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 608 AM CDT THU SEP 4 2014 MOISTURE TRANSPORT INTO THE REGION UNDERNEATH THE CAP HAS ALLOWED AN AREA OF IFR/MVFR CEILINGS TO FORM OVER THE AREA. THE 04.09Z RAP AND 04.06Z NAM SOUNDINGS SUGGEST THIS SHOULD PERSIST INTO THE MIDDLE OF THE MORNING BEFORE DISSIPATING AND WITH THE CAP OVER THE AREA...CONDITIONS SHOULD GO UP TO HIGH VFR CEILINGS. THE COLD FRONT OVER WESTERN MINNESOTA WILL PUSH INTO THE AREA STARTING LATE THIS AFTERNOON WITH INIDATIONS THAT THE CAP WILL START TO BREAK TO ALLOW MORE STORMS TO BEGIN DEVELOPING. WILL HAVE VCTS FOR A GOOD SHARE OF THE EVENING WITH A TWO HOUR TEMPO GROUP BASED ON THE 04.00Z HI-RES ARW WHEN THE STORMS ARE MOST PROBABLE TO MOVE ACROSS THE TAF SITES WITH MVFR AND POSSIBLY IFR CONDITIONS POSSIBLE. THE FRONT WILL THEN COME THROUGH IN THE OVERNIGHT HOURS SWINGING THE WINDS AROUND TO THE NORTHWEST. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
326 AM CDT THU SEP 4 2014 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 326 AM CDT THU SEP 4 2014 SURFACE MAP AS OF 3 AM THIS MORNING HAD A DEEP 996MB LOW OVER EASTERN SD WITH A WARM FRONT EXTENDING ACROSS SOUTHERN MN AND INTO SOUTHWEST WI. CURRENTLY WATCHING ONE CLUSTER OF STRONG THUNDERSTORMS DEPARTING THE AREA INTO NORTHEAST WI. WITHIN THE LAST 1/2 HOUR...A CLUSTER OF SHOWERS AND THUNDERSTORMS POPPED UP OVER FAR NORTHEAST IA/SOUTHWEST WI. FURTHER ANALYSIS SHOWING THESE SHOWERS AND STORMS FORMING IN RESPONSE TO A NOSE OF STRONG 850MB MOISTURE TRANSPORT WORKING NORTHEAST ACROSS IA...AND OCCURRING ABOVE A VERY STRONG 700- 750MB CAP OF 14C PER THE RAP BUFKIT AT BLUE RIVER WI. OTHERWISE... TEMPERATURES ACROSS THE AREA EARLY THIS MORNING WERE IN THE 60S ACROSS NORTH CENTRAL WI...AND IN THE 70S ELSEWHERE ACROSS THE ARX FORECAST AREA. WARM FRONT MAKES A PUSH NORTHEAST THROUGH THE REST OF THE AREA THIS MORNING. THINKING THOSE SHOWERS/STORMS WILL SHOVE OUT OF THE AREA AS CAP STRENGTHENS IN WARM SECTOR. WILL BE WATCHING AN MCS OVER ND MAKING ITS WAY EAST-SOUTHEAST...WHICH COULD CLIP CLARK AND TAYLOR COUNTIES AS IT MAKES ITS WAY ACROSS FAR NORTHERN WI/UPPER MI. MAY HAVE TO ADJUST POPS ACCORDINGLY. OTHERWISE...STRONG WARM AIR ADVECTION WILL TAKE PLACE ACROSS THE AREA WITH STRENGTHENING 700-750MB CAP. THIS SHOULD HOLD OFF ANY FURTHER CONVECTION AND PUSH TEMPERATURES WELL INTO THE 80S...TO A FEW LOWER 90S ALONG/SOUTH OF I-90. DEW POINTS WILL ALSO BE INCREASING INTO THE LOWER 70S THROUGH THE DAY...PRODUCING VERY WARM/MUGGY/UNCOMFORTABLE CONDITIONS. HEAT INDICES FOR THE MOST PART LOOK TO BE IN THE 90-100 RANGE...BUT COULD SEE A FEW HOURS OF 100- 105 IN A FEW SPOTS IN THE MISSISSIPPI/WISCONSIN RIVER VALLEYS. NOT THINKING A HEAT ADVISORY WILL BE NEEDED AT THIS POINT DUE TO THE BRIEF TOUCH IN THE CRITERIA RANGE. WILL HIT IT HARD WITH OUR OTHER PRODUCTS. CAP HOLDS STRONG INTO THE AFTERNOON HOURS AS A COLD FRONT PUSHES SOUTHEASTWARD INTO NORTHERN WI/SOUTH CENTRAL MN. MODELS AT ODDS AT HANDLING CONVECTION OR LACK THEREOF WHICH HEDGES ON STRENGTH OF CAP...WHICH IS VERY STRONG FOR THIS TIME OF YEAR. GFS/ECMWF/CANADIAN DETERMINISTIC MODELS ALL HOLD OFF DEVELOPING CONVECTION THROUGH 7PM. NAM IS A BIT MORE GUNG-HO FIRING ALONG THE FRONT BASICALLY NORTH OF I-94 BETWEEN 4-7PM. NMM/ARW WRF MODELS SIDE WITH THE NAM. REASON BEING... BUFKIT SOUNDINGS REVEAL POSSIBLY SOME ELEVATED CONVECTION BURBLING ABOVE THE CAP AS MID-LEVEL COOLING/STEEPENING LAPSE RATES TAKE PLACE WITH INCOMING MID-LEVEL TROUGH. THIS WOULD COMPROMISE THE CAP AND LET SURFACE BASED/DEEP CONVECTION RELEASE ALONG THE FRONT. WILL HAVE TO KEEP AN EYE ON THIS FOR SEVERE WIND/HAIL POTENTIAL AS 0- 3KM BULK SHEAR IS PLENTIFUL IN THE 30-40KT RANGE ALONG WITH MUCAPE IN THE 3000-4000J/KG RANGE. THE COLD FRONT CONTINUES TO PUSH SOUTHEAST THROUGH THE AREA FRIDAY NIGHT FOR CONTINUED THUNDERSTORM CHANCES. SOME OF THESE STORMS COULD BE REMAIN SEVERE AT LEAST INTO THE EVENING HOURS. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 326 AM CDT THU SEP 4 2014 WITH THE COLD FRONT PUSHED INTO NORTHERN IL BY FRIDAY MORNING... NORTHWEST WINDS WILL DRAW DRIER/COOLER AIR OVER THE FORECAST AREA. EXPECTING FAIRLY BREEZY NORTHWEST WINDS IN THE 15-25MPH RANGE WITH HIGHS ONLY TOPPING OFF IN THE UPPER 60S TO TO LOWER 70S. MORE EARLY FALL-LIKE CONDITIONS ARE THEN EXPECTED INTO THE WEEKEND AS CANADIAN HIGH PRESSURE DOMINATES THE CENTRAL CONUS/UPPER MISSISSIPPI RIVER VALLEY REGIONS. LOOK FOR MOSTLY CLEAR SKIES THROUGH SUNDAY WITH HIGHS SATURDAY AND SUNDAY IN THE 70S AND OVERNIGHT LOWS IN THE 40S TO LOWER 50S. FOR MONDAY THROUGH WEDNESDAY...DEEPENING CYCLONIC FLOW OVER CANADA AND NORTHERN CONUS WILL DRIVE A COUPLE TROUGHS THROUGH THE REGION FOR A PERIOD OF UNSETTLED WEATHER WITH ON/OFF SHOWER AND THUNDERSTORM CHANCES. TEMPERATURES ARE EXPECTED TO BE AT OR A FEW DEGREES BELOW NORMAL WITH HIGHS IN THE 70S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1212 AM CDT THU SEP 4 2014 SHOWERS AND STORMS REMAIN NORTHEAST OF THE TAF SITES EARLY THIS MORNING...NORTH OF A WARM FRONT SITUATED NEAR I-94.HOWEVER... THERE CONTINUE TO BE SIGNS FOR SHOWERS AND STORMS TO POP UP OVER SOUTHWEST WI BETWEEN 09-11Z AND PROGRESS EASTWARD...POSSIBLY IMPACTING LSE. THEREFORE...HAVE ADJUSTED THE TAF TO PIN DOWN THIS PERIOD AS THE MOST LIKELY TIME FRAME. VISIBILITIES AND CEILINGS COULD GO BRIEFLY DOWN TO MVFR WITH THIS ACTIVITY. CEILINGS BECOME THE NEXT CONCERN WITH SOME MODELS STILL WANTING TO DEVELOP IFR/MVFR STRATUS OVER THE TAF SITES. UNCERTAINTY STILL REMAINS WHETHER THIS WILL HAPPEN WITH THE AIR STAYING MIXED ON A BREEZY SOUTH WIND...THEREFORE...HAVE LEFT THE SCATTERED CEILINGS IN THE TAFS. MONITORING FOR LOW STRATUS WILL BE REQUIRED. ANY STRATUS SHOULD MIX OUT QUICKLY IN THE MORNING WITH DAYTIME HEATING... RESULTING IN VFR CONDITIONS FOR THE AFTERNOON. SOUTHWESTERLY GUSTS OF 20-25 KT SEEM LIKELY FOR THE AFTERNOON TOO. A COLD FRONT THEN MOVES THROUGH THE TAF SITES DURING THE EVENING. QUESTIONS REMAIN WHETHER THE FRONT CAN INITIATE STORMS...THEREFORE...ONLY HAVE A VCTS MENTION IN THE TAFS FOR NOW. WINDS LOOK TO SWING AROUND TO THE WEST WITH SPEEDS DECREASING AS THE FRONT PASSES. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...AJ
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
228 AM CDT THU SEP 4 2014 .SHORT TERM... TODAY...FORECAST CONFIDENCE IS MEDIUM. THE SECONDARY CONVECTIVE DEVELOPMENT...TIED WITH THE H8 WARM FRONT ON THE NOSE OF THE LOW LEVEL JET LEANING INTO THE AREA...IS EXPANDING QUICKLY ACROSS SOUTHWEST WI AT THE TIME OF THIS WRITING. FOR SOME REASON THE HRRR HAS DECIDED TO DUMP THIS DEVELOPMENT AND WENT DRY WITH THE 04 AND 05Z UPDATES. WELL...THAT/S NOT GOING TO WORK OUT. SATELLITE IMAGERY IS SHOWING A LOWER MID DECK EXPANDING QUICKLY UPSTREAM...HIGHLIGHTING THE CONVERGENCE OF WARM AND MOIST AIR ON THE NOSE OF THAT H8 JET. MOST OF THE MODELS SHOW THIS DEVELOPMENT OCCURRING EARLY THIS MORNING...EXITING BY MID TO LATE MORNING. ISOLATED SEVERE STORMS ARE POSSIBLE WITH WIND AND HAIL THE MAIN THREAT. THE RAIN WOULD BE HEAVY AND URBAN AND SMALL STREAM FLOODING IS POSIBLE IF ANY STORMS TURN AWAY FROM THE FASTER MEAN FLOW. ONCE THE STORMS MOVE OUT...WE GET INTO A VERY IMPRESSIVE THERMAL RIDGE AHEAD OF AN APPROACHING COLD FRONT. 925MB TEMPS CLIMB TO AN IMPRESSIVE 25-27C...IF WE GET ENOUGH SUNSHINE WE COULD SEE MANY AREAS HIT THE 90 MARK. I/M COMFORTABLE KEEPING WHAT WE HAVE IN THE FORECAST...WHICH IS ABOVE MOST GUIDANCE VALUES RIGHT NOW. THE AIRMASS OVER US TODAY WILL BE VERY HUMID WITH DEW POINTS REACHING THE LOWER 70S. THE HEAT INDEX WILL BE IN THE MID TO UPPER 90S. THANKFULLY THIS IS SHORT LIVED AS THE COLD FRONT COMING THROUGH TONIGHT WILL BRING MUCH COOLER TEMPS ON FRIDAY. TONIGHT...FORECAST CONFIDENCE IS MEDIUM. A STRONG COLD FRONT WILL PUSH THROUGH THE AREA OVERNIGHT. IT/S A RATHER LATE SHOW FOR SOUTHERN WISCONSIN AS THE FRONT DOESN/T REACH MADISON UNTIL ABOUT 6 AM FRIDAY AND MILWAUKEE ABOUT 9 AM. THE INITIAL DEVELOPMENT SHOULD OCCUR OVER ECNTRL MN AND WCNTRL WI THEN EXPAND AND ORGANIZE ALONG THE FRONT WITH TIME...HEADING SOUTHEAST INTO SOUTHERN WISCONSIN OVERNIGHT. THE AIRMASS WILL BE VERY MOIST AHEAD OF THE FRONT...BUT THE LATE TIMING WILL BEGIN TO LIMIT INSTABILITY OVER TIME. IN ADDITION...THE LOW LEVEL JET FOCUSES WELL EAST OF WISCONSIN BY THE TIME THE FRONT ARRIVES. WOULD EXPECT A FEW STORMS TO BECOME SEVERE NORTHWEST OF OUR FORECAST AREA...WHERE STORMS INTITIATE...THEN AS THEY DRIFT SOUTH INTO THE FORECAST AREA...THE INTENSITY WILL GRADUALLY DIMINISH. SPC HAS US IN A SLIGHT RISK OF SEVERE STORMS NORTH OF A PORT WASHINGTON TO MADISON TO DODGEVILLE LINE. THE FAR SOUTH WOULD STRUGGLE TO SEE SEVERE GIVEN THE TIMING. THIS LOOKS VERY REASONABLE. THE MAIN THREAT WILL BE WIND AND HAIL. FRIDAY AND FRIDAY NIGHT...FORECAST CONFIDENCE MEDIUM. THE SURFACE TO 850MB COLD FRONT WILL BE REACHING FAR SOUTHEAST WI AROUND 12Z...WHICH IS LATER THAN THE PAST SEVERAL MODEL RUNS. MEANWHILE... A STRONG MID LEVEL SHORTWAVE TROUGH WILL BE SLIDING ACROSS THE UPPER MIDWEST. AHEAD OF THIS TROUGH... THERE WILL BE WEAK SHORTWAVE ACTIVITY AND ALSO RISING MOTION IN THE RIGHT ENTRANCE REGION OF AN UPPER JET. THE AREA JUST BEHIND THE SURFACE COLD FRONT AND AHEAD OF THE UPPER TROUGH WILL LINE UP OVER SOUTHEAST WI DURING THE DAY FRIDAY AND KEEP THE POSSIBILITY OF SHOWERS AND ISOLATED THUNDERSTORMS GOING. THE LIMITING FACTOR FOR PRECIP IS A DRY LAYER FROM 5 TO 10 KFT. THE MODELS ARE MIXED ABOUT WHERE SHOWERS AND THUNDERSTORMS WILL TRACK FRIDAY AFTERNOON. MOST SUGGEST THE MAIN FORCING AND PRECIP WILL BE SOUTH OF THE WI/IL BORDER. THUS...WILL CONTINUE THE DIMINISHING TREND FOR POPS ON FRIDAY AFTERNOON AND EVENING. THERE SHOULD BE PLENTY OF CLOUDS OVER SOUTHERN WI ON FRIDAY. THAT AND THE COLD AIR ADVECTION WILL LIMIT HIGHS TO THE MID 70S. THE MID LEVEL SHORTWAVE TROUGH WILL EXIT SOUTHEAST WI BY AROUND MIDNIGHT FRIDAY NIGHT. THIS WILL USHER MUCH DRIER AND COOLER AIR INTO SOUTHERN WI WHICH WILL HANG AROUND THROUGH THE WHOLE WEEKEND AND MONDAY. .LONG TERM... SATURDAY THROUGH MONDAY...FORECAST CONFIDENCE HIGH. PLAN ON A QUIET STRETCH OF WEATHER FOR THE WEEKEND WITH LOW HUMIDITY AND COOLER TEMPERATURES. HIGHS WILL BE IN THE LOWER TO MID 70S WITH PLENTY OF SUNSHINE. LOWS WILL DROP DOWN INTO THE LOWER 50S...WITH SATURDAY NIGHT LOOKING LIKE THE COOLEST. DEWPOINT DEPRESSIONS SHOULD BE FAIRLY LOW WITH LIGHT WINDS...SO PATCHY FOG LOOKS POSSIBLE. MONDAY NIGHT THROUGH THURSDAY...FORECAST CONFIDENCE MEDIUM. THE ECMWF AND GFS ARE NOW OUT OF PHASE FOR THE NEXT WARM AIR ROUND OF THUNDERSTORMS IMPACTING SOUTHERN WI MONDAY NIGHT AND TUESDAY. THE GFS IS ROUGHLY 6 HOURS SLOWER WITH THE PRECIP AND HAS A WEAKER- LOOKING SHORTWAVE TROUGH DUE TO THE EARLIER ARRIVAL OF AN UPPER JET STREAK. THEN THE TWO MODELS ARE BACK INTO GENERAL AGREEMENT ABOUT A BACK DOOR COLD FRONT DROPPING DOWN THE LAKE INTO SOUTHERN WI LATE TUESDAY NIGHT. THERE IS NOT MUCH FORCING FOR PRECIP...SO LOW CLOUDS AND MAYBE A FEW SPRINKLES WOULD BE POSSIBLE THROUGH WED MORNING. THEN THERE SHOULD BE A PERIOD OF QUIET WEATHER WITH EASTERLY WINDS OVER SOUTHERN WI THROUGH WED NIGHT. THEREFORE...WENT WITH A LOWERING TREND FOR POPS AND THUNDER IN THE FORECAST. ANOTHER ROUND OF SHOWERS AND STORMS ARE POSSIBLE FOR SOUTHERN WI AS A MID LEVEL TROUGH SLIDES FROM THE NORTHERN PLAINS TO THE GREAT LAKES REGION LATE IN THE WEEK...THURSDAY THROUGH FRIDAY NIGHT. THERE ARE STILL PLENTY OF MODEL DIFFERENCES THAT WILL NEED TO BE IRONED OUT BEFORE DECIDING THE EXTENT OF THUNDER. && .AVIATION/12Z TAFS/... IN GENERAL...EXPECT VFR CONDITIONS THROUGH THE TAF PERIOD. HOWEVER...THERE ARE A COUPLE OF OPPORTUNITIES FOR LOWER CONDITIONS. WE SHOULD SEE AT LEAST SCATTERED CONVECTION THIS MORNING AS A WARM FRONT MOVES THROUGH. CONDITIONS WOULD DETERIORATE TO MVFR OR EVEN IFR LEVELS IN ANY STRONGER STORMS. THINGS SHOULD CLEAR OUT BY LATE MORNING AS HOT AIR ARRIVES AHEAD OF AN APPROACHING COLD FRONT. LOOK FOR RATHER BREEZY CONDITIONS WITH A SOUTH TO SOUTHWEST WIND LATER THIS MORNING AND AFTERNOON. THE COLD FRONT ARRIVES LATE TONIGHT...REACHING MADISON AROUND 12Z FRIDAY AND KMKE/KUES/KENW AROUND 15-16Z FRI. IT LOOKS LIKE THERE COULD BE A SHORT PERIOD OF MVFR CIGS/VSBYS IN THE COLD AIR ADVECTION IN THE IMMEDIATE WAKE OF THE FRONT. THUNDERSTORMS ARE ALSO POSSIBLE WITH THE FRONTAL PASSAGE LATE TONIGHT. && .MARINE... SOUTH TO SOUTHWEST WINDS TODAY WILL GUST TO AROUND 25 KNOTS...SO A SMALL CRAFT ADVISORY IS IN EFFECT FROM 10 AM TO 10 PM TODAY. WAVES WILL INCREASE TO 3 TO 5 FEET THURSDAY...THE HIGHEST WAVES IN THE NORTH. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 10 PM CDT THIS EVENING FOR LMZ643>646. && $$ TODAY/TONIGHT AND AVIATION/MARINE...DAVIS FRIDAY THROUGH WEDNESDAY...MRC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1212 AM CDT THU SEP 4 2014 .UPDATE... ISSUED AT 1212 AM CDT THU SEP 4 2014 SHORTWAVE ON WATER VAPOR AND RADAR IMAGERY PROGRESSING ACROSS NORTHEAST WI AND WESTERN UPPER MI CURRENTLY CONTINUES TO BRING SHOWERS AND STORMS TO TAYLOR AND CLARK COUNTIES. HOWEVER...THESE STORMS ARE A LOT WEAKER NOW COMPARED TO A COUPLE HOURS AGO...DESPITE A DECENT INSTABILITY FEED INTO THEM ON A LOW LEVEL JET. BELIEVE PART OF THIS REASON IS THAT THE NOSE OF THE 925-850MB MOISTURE TRANSPORT ASSOCIATED WITH THE SHORTWAVE HAS NOW SHIFTED OFF TO NORTHEAST WI AND EASTERN UPPER MI. THEREFORE...THE SEVERE THUNDERSTORM WATCH WAS CANCELLED ABOUT AN HOUR AGO. THE STORMS ARE STILL DUMPING HEAVY RAIN...ENOUGH THAT CONDITIONS WERE GETTING CLOSE OVER NORTHERN CLARK COUNTY FOR A FLOOD RELATED PRODUCT. HOWEVER...THOSE STORMS ARE DROPPING SOUTHEAST AND DIMINISHING FROM THE WEST...WHICH BOTH ARE HELPING TO PRECLUDE THE NEED FOR ANY FLOOD ADVISORY OR WARNING. CONDITIONS STILL LOOK FAVORABLE FOR SHOWERS AND STORMS TO POP UP OVER SOUTHWEST WISCONSIN TOWARDS 09-10Z. THESE WILL FORM FROM ANOTHER SURGE OF 850MB MOISTURE TRANSPORT COMING UP FROM IOWA AHEAD OF A SHORTWAVE IN CENTRAL IOWA. IN FACT...THIS SHORTWAVE HAS HELPED MAINTAIN A CLUSTER OF STORMS NOW TRACKING EAST OF DES MOINES. STILL ANTICIPATING HEAVY RAIN TO BE THE MAIN CONCERN WITH ANY STORMS THAT POP UP...THOUGH THEY TOO SHOULD BE PROGRESSIVE TO THE EAST TO LIMIT ANY FLOOD THREAT. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 350 PM CDT WED SEP 3 2014 AT 3 PM...A WARM FRONT EXTENDED FROM WOODLAKE MINNESOTA SOUTHEAST TO FAIRFIELD IOWA /SOUTHEAST CORNER OF THE STATE/. DEW POINTS SOUTH OF THIS FRONT WERE IN THE LOWER 70S. MEANWHILE NORTH OF THIS FRONT DEW POINTS RANGED FROM MID 50S TO MID 60S. THE LOWEST DEW POINTS WERE FOUND ACROSS CENTRAL WISCONSIN. THERE IS NO WEATHER CURRENTLY ASSOCIATED WITH THIS FRONT. MEANWHILE FURTHER NORTH...A GENERALLY WEST TO EAST BAND OF PRECIPITATION WAS LOCATED FROM ALEXANDRIA MINNESOTA TO MERRILL WISCONSIN. THIS BAND WAS DEVELOPING IN AN AREA OF 850 TO 700 MB FRONTOGENESIS FORCING AND MOISTURE TRANSPORT. IN ADDITION...THERE IS A SHORT WAVE TROUGH MOVING THROUGH NORTHERN MINNESOTA. THE LATEST RAP SUGGESTS THAT THIS WAVE WILL TAKE THE BEST 850 TO 700 MB MOISTURE TRANSPORT NORTH NORTHEAST TOWARD UPPER MICHIGAN THIS EVENING. MOST OF THE MESO MODELS SUGGEST THAT THIS BAND OF PRECIPITATION WILL REMAIN ACROSS CENTRAL MINNESOTA AND NORTHERN WISCONSIN THIS EVENING. THIS BAND MAY POSSIBLY IMPACT TAYLOR AND CLARK COUNTIES IN NORTH- CENTRAL WISCONSIN. THERE IS SUFFICIENT 0-6KM SHEAR FOR SUPERCELL DEVELOPMENT INITIALLY AND THIS EVOLVES INTO A LINE AS THE COLD POOL DEVELOPS. THE MAIN SEVERE WEATHER THREATS WOULD BE DAMAGING WINDS AND POSSIBLY LARGE HAIL BETWEEN 04.02Z AND 04.06Z. IN ADDITION WITH WARM CLOUD LAYERS DEPTHS AROUND 4 KM AND PRECIPITABLE WATER AROUND 1.5 INCHES...THE STORMS WILL BE EFFICIENT RAIN PRODUCERS. WE WILL HAVE TO WATCH CLOSELY FOR TRAINING CELLS. FOR THE OVERNIGHT...THERE IS QUITE A BIT OF UNCERTAINTY ON HOW THINGS WILL EVOLVE. THE LATEST RAP SUGGESTS THAT ANOTHER WING OF STRONG 850 MB TO 700 MB MOISTURE TRANSPORT DEVELOPS OVER NORTHEAST IOWA AS ANOTHER SHORT WAVE /CURRENTLY OVER SOUTH DAKOTA/ MOVES INTO THE AREA. THIS WOULD SUGGEST THE POSSIBILITY THAT ANOTHER AREA OF SHOWERS AND STORMS WILL DEVELOP ACROSS EAST-CENTRAL MINNESOTA AND WEST-CENTRAL WISCONSIN. LIKE ITS PREDECESSOR...THE STORMS WOULD INITIALLY FORM AS SUPERCELLS AND THEN EVOLVE INTO ANOTHER LINE OR LINES OF STORMS WOULD DROP SOUTH ALONG AND NORTH ACROSS WESTERN WISCONSIN WITH A MAJORITY OF THE ACTIVITY ALONG AND NORTH OF THE INTERSTATE 94 CORRIDOR. THIS IS ACTUALLY IN DECENT AGREEMENT WITH WHAT THE 03.12Z NAM...ARW...AND NMM IS SHOWING IN THEIR DETERMINISTIC SOLUTIONS. THE MAIN THREAT WOULD BE HAIL INITIALLY AND THEN QUICKLY EVOLVE INTO A WIND THREAT AS THEY FOLLOW THE CORFIDI VECTORS TO THE SOUTHEAST INTO THE HIGHER CAPES. ANOTHER SCENARIO SHOWS UP IN THE SPC WRF WHERE IT TAKES THE CURRENT LINE OF CONVECTION AND DIVES THIS SOUTH THROUGH OUR FORECAST AREA. OVERALL PREFER THE LATTER SOLUTION...SO TRENDED THE FORECAST TOWARD IT. ON THURSDAY...A STRONG CAP DEVELOPS ACROSS THE AREA. 700 MB TEMPERATURES IN THIS CAP CLIMB TO 14C. THIS IS THE STRONGEST CAP OF THE YEAR FOR OUR AREA. BOTH THE GFS AND ECMWF SUGGEST THAT THIS CAP WILL KEEP MOST OF THE AREA DRY FOR THIS TIME PERIOD. MEANWHILE THE NAM SHOWS THAT A SHORT WAVE...CURRENTLY OVER COLORADO...WILL MOVE THROUGH NORTH CENTRAL WISCONSIN DURING THE AFTERNOON. THE LIFT ASSOCIATED WITH THIS WAVE CAUSE THIS CAP TO COOL INTO THE 8C TO 10C RANGE. WITH MOST UNSTABLE CAPES IN THE 2 TO 4K RANGE...THUNDERSTORMS WOULD RAPIDLY DEVELOP. THE 0-6 KM SHEAR WOULD BE SUFFICIENT FOR SUPERCELLS INITIALLY...AND THEN QUICKLY EVOLVE INTO A LINE AS THE 0-3KM SHEAR TAKES OVER. CONFIDENCE IN THIS SCENARIO WAS NOT EXCEPTIONALLY HIGH...SO KEPT PRECIPITATION CHANCES IN THE 20 TO 50 PERCENT RANGE. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 350 PM CDT WED SEP 3 2014 ON THURSDAY NIGHT...THE 03.12Z MODELS CONTINUE TO SHOW THAT A STRONG CANADIAN COLD FRONT WILL MOVE EAST THROUGH THE FORECAST AREA. THIS FRONT WILL BE MOVING EAST INTO 3 TO 5K MOST UNSTABLE CAPES. THE BEST LIFT WITH THIS WAVE IS FURTHER NORTH...SO IT IS GOING TO TAKE SOME TIME TO COOL THE CAP. SO THERE ARE SOME QUESTIONS ACROSS SOUTHEAST MINNESOTA AND NORTHEAST IOWA ON HOW WIDESPREAD AND HOW FAST THE STORMS WILL DEVELOP. WHILE THE 0-6KM SHEAR IS NOT AS STRONG AS IT WILL BE TONIGHT AND ON THURSDAY... THE 0-3 KM SHEAR WILL BE SUFFICIENT FOR SOME DAMAGING WINDS. IN ADDITION...THE STRONG CAPES MAY ALSO AID IN THE DEVELOPMENT OF LARGE HAIL. ON SATURDAY NIGHT...ANOTHER SHORT WAVE TROUGH WILL MOVE THROUGH THE AREA. WITH THE AIRMASS RATHER DRY...EXPECT THAT THIS SYSTEM WILL JUST BRING ANOTHER REINFORCING SHOT OF COOL AIR. FROM MONDAY NIGHT INTO TUESDAY...A LONG WAVE TROUGH WILL MOVE THROUGH THE REGION. WHILE THE GFS HAS THIS SYSTEM NEGATIVELY TILTED...THE BEST 0-6 KM STAYS TO OUR SOUTH. IN ADDITION...THE TIMING OF THIS WAVE IS NOT THAT FAVORABLE FOR THAT MUCH INSTABILITY ACROSS OUR AREA. AS A RESULT...NOT EXPECTING ANY SEVERE WEATHER AT THIS TIME. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1212 AM CDT THU SEP 4 2014 SHOWERS AND STORMS REMAIN NORTHEAST OF THE TAF SITES EARLY THIS MORNING...NORTH OF A WARM FRONT SITUATED NEAR I-94.HOWEVER... THERE CONTINUE TO BE SIGNS FOR SHOWERS AND STORMS TO POP UP OVER SOUTHWEST WI BETWEEN 09-11Z AND PROGRESS EASTWARD...POSSIBLY IMPACTING LSE. THEREFORE...HAVE ADJUSTED THE TAF TO PIN DOWN THIS PERIOD AS THE MOST LIKELY TIME FRAME. VISIBILITIES AND CEILINGS COULD GO BRIEFLY DOWN TO MVFR WITH THIS ACTIVITY. CEILINGS BECOME THE NEXT CONCERN WITH SOME MODELS STILL WANTING TO DEVELOP IFR/MVFR STRATUS OVER THE TAF SITES. UNCERTAINTY STILL REMAINS WHETHER THIS WILL HAPPEN WITH THE AIR STAYING MIXED ON A BREEZY SOUTH WIND...THEREFORE...HAVE LEFT THE SCATTERED CEILINGS IN THE TAFS. MONITORING FOR LOW STRATUS WILL BE REQUIRED. ANY STRATUS SHOULD MIX OUT QUICKLY IN THE MORNING WITH DAYTIME HEATING... RESULTING IN VFR CONDITIONS FOR THE AFTERNOON. SOUTHWESTERLY GUSTS OF 20-25 KT SEEM LIKELY FOR THE AFTERNOON TOO. A COLD FRONT THEN MOVES THROUGH THE TAF SITES DURING THE EVENING. QUESTIONS REMAIN WHETHER THE FRONT CAN INITIATE STORMS...THEREFORE...ONLY HAVE A VCTS MENTION IN THE TAFS FOR NOW. WINDS LOOK TO SWING AROUND TO THE WEST WITH SPEEDS DECREASING AS THE FRONT PASSES. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ UPDATE...AJ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...AJ
AREA FORECAST DISCUSSION
NWS ALBANY NY
146 AM EDT SAT SEP 6 2014 .SYNOPSIS... A FLOW OF WARM AND HUMID SOUTHERLY AIR WILL CONTINUE TO RESULT IN ABOVE NORMAL TEMPERATURES INTO SATURDAY. A COLD FRONT APPROACHING FROM THE GREAT LAKES AND SOUTHEAST CANADA WILL CROSS OUR REGION ON SATURDAY...BRINGING SHOWERS AND THUNDERSTORMS. SOME OF THE THUNDERSTORMS MAY BE STRONG TO SEVERE. MUCH COOLER AND DRIER AIR WILL MOVE IN FOR SUNDAY AND MONDAY...AS HIGH PRESSURE BUILDS IN FROM THE WEST. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1215 AM EDT...A MUGGY EVENING CONTINUES WITH SOME HAZE AS DEWPOINTS WERE HOVERING 70F AND WIDELY SCATTERED CLOUDS. STRATUS HAS BECOME MORE PRONOUNCED INTO PORTIONS OF THE CATSKILLS...NW CT AND SOUTHERN BERKS PER THE 11U-3.9U IMAGERY. THIS WILL LIKELY SPREAD A BIT OVERNIGHT AS OUR REGION REMAINS FIRMLY ENTRENCHED IN A WARM SECTOR AHEAD OF A COLD FRONT APPROACHING FROM THE GREAT LAKES AS WELL AS A PRE FRONTAL TROUGH APPROACHING FROM WESTERN NEW YORK. THE IMPRESSIVE LINE OF CONVECTION IN THE VICINITY OF THE COLD FRONT WAS CROSSING LOWER ONTARIO PROVINCE AND IS NOW SHOWING SIGNS OF WEAKENING. THE LATEST MESOSCALE MODELS SUCH AS THE HRRR AND LOCAL HI RES WRF INDICATING LINES/CLUSTERS OF CONVECTION WILL APPROACH CENTRAL NY LATE THIS EVENING IT IS FORECAST TO WEAKEN FURTHER IN INTENSITY...AND BY THE TIME IT POTENTIALLY REACHES EAST CENTRAL NEW YORK LATE TONIGHT CONVECTION SHOULD DISSIPATE AS IT OUTRUNS THE FORCING ASSOCIATED WITH THE FRONT. SO WILL ONLY MENTION SLIGHT CHANCE TO LOW CHANCE POPS THROUGH THE NIGHT WEST OF THE CAPITAL REGION...WITH THE HIGHER VALUES ACROSS THE WESTERN ADIRONDACKS AND MOHAWK VALLEY. HIGHEST CONFIDENCE FOR AREAS FROM THE CAPITAL REGION EASTWARD REMAINING RAIN-FREE THROUGH SUNRISE SATURDAY. MINIMUM TEMPERATURES ONLY EXPECTED TO DROP INTO THE 60S REGION-WIDE. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/... SATURDAY LOOKS TO BE A CONVECTIVELY ACTIVE DAY ACROSS MUCH OF THE AREA...AS A COLD FRONT SWEEPS FROM NORTHWEST TO SOUTHEAST DURING THE DAY. IT WILL REMAIN QUITE HUMID...SO ANY BREAKS OF SUNSHINE EARLY WILL LEAD TO RAPID DESTABILIZATION AHEAD OF THE COLD FRONT. THE BEST CHANCE FOR SOME EARLY SUNSHINE WHERE FORECAST SBCAPE VALUES COULD REACH 1500-2500 J/KG...IS FROM AROUND THE ALBANY AND SARATOGA REGIONS SOUTH AND EAST. FLOW ALOFT WILL STEADILY INCREASE THROUGH THE AFTERNOON...WHICH WILL ALLOW THE SHEAR TO STRENGTHEN AS WELL. DEEP LAYER SHEAR OF 25-35 KT AND THE APPROACHING COLD FRONT WILL LIKELY ALLOW FOR ORGANIZED CLUSTERS/BOWS TO DEVELOP...WITH DAMAGING WINDS THE MAIN THREAT AS FAIRLY WEAK MID-LEVEL LAPSE RATES SHOULD PRECLUDE A HAIL THREAT. EFFICIENT DOWNPOURS WILL ALSO BE POSSIBLE WITH ANY STORMS. HOWEVER...GIVEN THE INCREASING FLOW AND RECENT DRY GROUND CONDITIONS...WE ARE NOT EXPECTING HYDRO RELATED PROBLEMS EXCEPT FOR ISOLATED MINOR URBAN/POOR DRAINAGE FLOODING POSSIBLE. BASED ON TIMING FROM THE 12Z GUIDANCE SUITE AND LOCAL HI RES WRF...TIMING FOR CONVECTION LOOKS TO BE LATE MORNING TO EARLY AFTERNOON FOR AREAS NORTH AND WEST OF THE CAPITAL REGION...MID TO LATE AFTERNOON FOR THE CAPITAL REGION...SARATOGA REGION...SOUTHERN VERMONT AND THE CATSKILLS...AND LATE AFTERNOON TO EARLY EVENING FOR THE MID HUDSON VALLEY...TACONICS AND BERKSHIRES/LITCHFIELD HILLS. DUE TO THE TIMING...BEST CHANCES FOR SEVERE STORMS WILL BE FROM CENTRAL MOHAWK VALLEY AND SARATOGA REGION SOUTH AND EAST. THIS INCLUDES THE GREATER CAPITAL DISTRICT AND ALL POINTS SOUTH AND EAST. WILL CONTINUE TO MENTION POTENTIAL FOR DAMAGING WINDS IN THE HWO FOR THESE AREAS. DUE TO THE COLD FRONT FRONT CROSSING THE REGION...MAXIMUM TEMPERATURES WILL RANGE FROM LOWER TO MID 70S ACROSS THE ADIRONDACKS...TO LOWER TO MID 80S FROM ALBANY SOUTH AND EAST. IT WILL REMAIN HUMID FOR MUCH OF THE AREA FOR MOST OF THE DAY...WITH DEWPOINTS SPIKING IN THE UPPER 60S TO LOWER 70S. ANY LINES OF CONVECTION SHOULD BE EAST OF THE AREA BY DARK...WHICH WILL END THE SEVERE THREAT. JUST A FEW LINGERING SHOWERS WILL BE POSSIBLE FOR THE REST OF THE EVENING...ESPECIALLY ACROSS SOUTHERN AREAS. COOLER AND DRIER AIR WILL FILTER INTO THE REGION OVERNIGHT WITH A NORTHWEST BREEZE. TEMPERATURES WILL BE NOTICEABLY COOLER BY EARLY SUNDAY MORNING. DRY WEATHER AND SEASONABLY COOLER TEMPERATURES ALONG WITH PLENTY OF SUNSHINE EXPECTED FOR SUNDAY AND MONDAY...AS HIGH PRESSURE BUILDS EASTWARD AND SETTLES ACROSS THE NORTHEAST CONUS. HUMIDITY LEVELS WILL BE QUITE COMFORTABLE...WITH COOL NIGHT TIME TEMPERATURES. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... MONDAY NIGHT INTO TUESDAY...MOST OF THE REGION WILL SEE TRANQUIL CONDITIONS WITH AVERAGE TEMPERATURES ACROSS THE REGION. 05/12Z MODEL AND NUMERICAL GUIDANCE DOES SHOW A WEAK LOW PRESSURE SYSTEM WITH TROPICAL ORIGINS MOVING SLOWLY UP THE EAST COAST. MOST OF THE REGION NORTH OF THE LOWER MID HUDSON VALLEY WILL BE FAR ENOUGH REMOVED FROM THE TRACK OF THIS COASTAL LOW. THIS WILL BRING SCATTERED CLOUD COVER TO THE REGION BUT MOST REGIONS WILL REMAIN DRY WITH THE EXCEPTION OF ISOLATED POPS ACROSS OUR FAR SOUTHEASTERN AREAS CLOSER TO THE CENTER OF THE COASTAL LOW PRESSURE SYSTEM. HIGH TEMPERATURES ON TUESDAY WILL RANGE FROM THE UPPER 60S IN THE HIGH TERRAIN TO LOWER AND MID 70S ACROSS VALLEY LOCATIONS. TUESDAY NIGHT THROUGH FRIDAY...OUR NEXT WEATHER SYSTEM WILL BE MAKING ITS WAY INTO THE REGION. MOST 12Z MODELS SHOW HIGHER PROBABILITIES OF PRECIPITATION AS WE GO FROM THURSDAY INTO THURSDAY EVENING. AS AN UPPER LEVEL LOW MOVES EQUATORWARD OUT OF CANADA AS WE GO INTO THE DAY ON WEDNESDAY...A SERIES OF WEAK LOW PRESSURE IMPULSES MOVING NORTHEASTWARD AROUND A BROAD 500 HPA CIRCULATION OVER THE UPPER MIDWEST WILL PROVIDE ISOLATED TO SCATTERED SHOWERS OVER OUR REGION...MAINLY DIURNALLY DRIVEN AS TEMPERATURES BEGIN TO RISE INTO THE MID AND UPPER 70S ON WEDNESDAY WITH DEWPOINT TEMPERATURES ON THE RISE AS WELL WITH A SOUTHERLY FLOW. AS WE GO INTO THE DAY ON THURSDAY...THIS IS WHERE GLOBAL MODELS AND PROBABILISTIC GUIDANCE DIVERGE IN CONFIDENCE FROM EACH OTHER. MODELS RANGE FROM A CONTINUATION ON IMPULSES WHERE A WEAK SURFACE LOW MAY DEVELOP JUST EAST OF OUR REGION THURSDAY AFTERNOON TO A MORE POTENT SURFACE LOW DEVELOPMENT NEAR THE OHIO VALLEY UNDER A FAVORABLE POSITION WITHIN A 100 KT JET STREAK PUTTING OUR REGION IN THE WARM SECTOR FROM AN APPROACHING COLD FRONT AS WE GO INTO THURSDAY EVENING. THIS FORECAST WILL BE UPDATED AS WE GET CLOSER TO THE EVENT AND AS CONFIDENCE INCREASES. HIGH TEMPERATURES ON THURSDAY WILL REMAIN NEAR AVERAGE ON THURSDAY. AS WE APPROACH THE END OF THE WEEK ON FRIDAY...TRANQUIL WEATHER LOOKS TO RETURN TO THE REGION WITH TEMPERATURES SLIGHTLY BELOW AVERAGE WITH A WEST TO NORTHWESTERLY FLOW BEHIND THE PASSING COLD FRONT. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... THROUGH DAYBREAK...A COMPLEX SITUATION...AS THE REGION REMAINS WITHIN THE WARM SECTOR OF A LOW PRESSURE SYSTEM CURRENTLY ACROSS SOUTHERN CANADA...WITH A COLD FRONT APPROACHING FROM THE GREAT LAKES REGION. LOW CLOUDS ARE EXPANDING NORTHWARD ACROSS WESTERN NEW ENGLAND...WITH MVFR CIGS TRENDING TO IFR AT KPSF THROUGH 12Z/SAT. SOME OF THESE LOW CLOUDS ARE LIKELY TO EXPAND...OR REDEVELOP FURTHER WEST INTO THE HUDSON RIVER VALLEY TOWARD 10Z/SAT. AT THIS TIME...HAVE INDICATED MAINLY LOW MVFR CIGS...BUT A PERIOD OF IFR CIGS CAN NOT BE RULED OUT AT KPOU/KALB/KGFL AFTER 10Z/SAT. SOME SHOWERS...ASSOCIATED WITH REMNANT CONVECTION OVER WESTERN/CENTRAL NYS MAY REACH KGFL AFTER 08Z/SAT. AFTER DAYBREAK...MVFR/IFR CIGS SHOULD GRADUALLY LIFT BETWEEN 12Z-15Z/SAT...LAST AT KPSF. THEREAFTER...MAINLY VFR CONDITIONS ARE EXPECTED THROUGH MOST OF THE DAY OUTSIDE OF SHOWERS AND THUNDERSTORMS PRECEDING AND ACCOMPANYING THE COLD FRONTAL BOUNDARY. THE COLD FRONT IS EXPECTED TO PASS THROUGH KGFL/KALB BETWEEN ROUGHLY 16Z-18Z/SAT...AND KPSF/KPOU BETWEEN ROUGHLY 18Z-22Z/SAT...LAST AT KPOU. THE POSSIBILITY FOR EMBEDDED THUNDERSTORMS WILL BE GREATEST AT KPSF AND KPOU...WHERE INSTABILITY WILL BE SOMEWHAT GREATER...SO HAVE INCLUDED MENTION OF VCTS IN THESE LOCATIONS...WITH SHRA MENTIONED ELSEWHERE...ALTHOUGH CAN NOT RULE OUT SOME THUNDER. AGAIN...BEST CHANCE FOR SHOWERS AND POSSIBLE THUNDERSTORMS WILL BE WITH OR JUST BEFORE THE COLD FRONT PASSES. SOME LINGERING SHOWERS MAY OCCUR AT KPOU AND KPSF THROUGH EARLY EVENING...OTHERWISE JUST SOME PATCHY MVFR CIGS ARE POSSIBLE THROUGH MIDNIGHT...ESP AT KPSF. WINDS WILL BE MAINLY FROM THE SOUTH TO SOUTHWEST AT 5-10 KT THROUGH DAYBREAK...AND 8-12 KT AFTER DAYBREAK...BEFORE SHIFTING INTO THE WEST...THEN NORTHWEST THIS AFTERNOON AT SIMILAR SPEEDS AS THE FRONT MOVES THROUGH. WEST TO NORTHWEST WINDS WILL PERSIST AT 5-10 KT SAT NT. WINDS WILL BE VARIABLE IN DIRECTION...AND MUCH STRONGER IN AND NEAR ANY THUNDERSTORMS. LOW LEVEL WIND SHEAR WILL BE POSSIBLE THROUGH DAYBREAK AT KGFL...WHERE SFC WINDS WILL REMAIN LIGHTER...WHILE WINDS AROUND 2000 FT AGL WILL BE MAINLY SOUTHWEST AT 30-35 KT. OUTLOOK... SATURDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. SUNDAY TO MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. TUESDAY TO TUESDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. WEDNESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA. && .FIRE WEATHER... A FLOW OF WARM AND HUMID SOUTHERLY AIR WILL CONTINUE TO RESULT IN ABOVE NORMAL TEMPERATURES INTO SATURDAY. A COLD FRONT APPROACHING FROM THE GREAT LAKES AND SOUTHEAST CANADA WILL CROSS OUR REGION ON SATURDAY...BRINGING SHOWERS AND THUNDERSTORMS. SOME OF THE THUNDERSTORMS MAY BE STRONG TO SEVERE. MUCH COOLER AND DRIER AIR WILL MOVE IN FOR SUNDAY AND MONDAY...AS HIGH PRESSURE BUILDS IN FROM THE WEST. RELATIVE HUMIDITY VALUES WILL INCREASE TO AROUND 90 TO 100 PERCENT TONIGHT...THEN DROP TO MINIMUM VALUES OF BETWEEN 55 AND 65 PERCENT SATURDAY AFTERNOON. MAXIMUM RH VALUES SATURDAY NIGHT ARE EXPECTED TO BE AROUND 90 TO 100 PERCENT. WINDS TONIGHT ARE EXPECTED TO BE SOUTHERLY AROUND 5 TO 10 MPH. SOUTHERLY WINDS WILL SHIFT TO THE WEST BEHIND A COLD FRONT SATURDAY AFTERNOON. WINDS WILL BECOME NORTHWESTERLY AROUND 5 TO 10 MPH SATURDAY NIGHT. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE EXPECTED THROUGH AT LEAST THE NEXT 5 DAYS. SHOWERS AND THUNDERSTORMS WILL DEVELOP AND OVERSPREAD THE AREA FROM NORTHWEST TO SOUTHEAST ON SATURDAY AHEAD OF A COLD FRONT. WHILE BASIN AVERAGE RAINFALL AMOUNTS LOOK TO BE UNDER A HALF INCH...LOCALIZED RAINFALL AMOUNTS OF OVER 2 INCHES ARE POSSIBLE WHICH MAY CAUSE ISOLATED MINOR FLOODING OF URBAN/POOR DRAINAGE AREAS. DRIER WEATHER IS THEN EXPECTED SATURDAY NIGHT THROUGH TUESDAY...AS HIGH PRESSURE ASSOCIATED WITH RELATIVELY COOL AIR SETTLES OVER THE REGION. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...JPV NEAR TERM...BGM/11/JPV SHORT TERM...JPV LONG TERM...IAA/LFM AVIATION...KL FIRE WEATHER...JPV HYDROLOGY...11/JPV
AREA FORECAST DISCUSSION
NWS ALBANY NY
1217 AM EDT SAT SEP 6 2014 .SYNOPSIS... A FLOW OF WARM AND HUMID SOUTHERLY AIR WILL CONTINUE TO RESULT IN ABOVE NORMAL TEMPERATURES INTO SATURDAY. A COLD FRONT APPROACHING FROM THE GREAT LAKES AND SOUTHEAST CANADA WILL CROSS OUR REGION ON SATURDAY...BRINGING SHOWERS AND THUNDERSTORMS. SOME OF THE THUNDERSTORMS MAY BE STRONG TO SEVERE. MUCH COOLER AND DRIER AIR WILL MOVE IN FOR SUNDAY AND MONDAY...AS HIGH PRESSURE BUILDS IN FROM THE WEST. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 1215 AM EDT...A MUGGY EVENING CONTINUES WITH SOME HAZE AS DEWPOINTS WERE HOVERING 70F AND WIDELY SCATTERED CLOUDS. STRATUS HAS BECOME MORE PRONOUNCED INTO PORTIONS OF THE CATSKILLS...NW CT AND SOUTHERN BERKS PER THE 11U-3.9U IMAGERY. THIS WILL LIKELY SPREAD A BIT OVERNIGHT AS OUR REGION REMAINS FIRMLY ENTRENCHED IN A WARM SECTOR AHEAD OF A COLD FRONT APPROACHING FROM THE GREAT LAKES AS WELL AS A PRE FRONTAL TROUGH APPROACHING FROM WESTERN NEW YORK. THE IMPRESSIVE LINE OF CONVECTION IN THE VICINITY OF THE COLD FRONT WAS CROSSING LOWER ONTARIO PROVINCE AND IS NOW SHOWING SIGNS OF WEAKENING. THE LATEST MESOSCALE MODELS SUCH AS THE HRRR AND LOCAL HI RES WRF INDICATING LINES/CLUSTERS OF CONVECTION WILL APPROACH CENTRAL NY LATE THIS EVENING IT IS FORECAST TO WEAKEN FURTHER IN INTENSITY...AND BY THE TIME IT POTENTIALLY REACHES EAST CENTRAL NEW YORK LATE TONIGHT CONVECTION SHOULD DISSIPATE AS IT OUTRUNS THE FORCING ASSOCIATED WITH THE FRONT. SO WILL ONLY MENTION SLIGHT CHANCE TO LOW CHANCE POPS THROUGH THE NIGHT WEST OF THE CAPITAL REGION...WITH THE HIGHER VALUES ACROSS THE WESTERN ADIRONDACKS AND MOHAWK VALLEY. HIGHEST CONFIDENCE FOR AREAS FROM THE CAPITAL REGION EASTWARD REMAINING RAIN-FREE THROUGH SUNRISE SATURDAY. MINIMUM TEMPERATURES ONLY EXPECTED TO DROP INTO THE 60S REGION-WIDE. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/... SATURDAY LOOKS TO BE A CONVECTIVELY ACTIVE DAY ACROSS MUCH OF THE AREA...AS A COLD FRONT SWEEPS FROM NORTHWEST TO SOUTHEAST DURING THE DAY. IT WILL REMAIN QUITE HUMID...SO ANY BREAKS OF SUNSHINE EARLY WILL LEAD TO RAPID DESTABILIZATION AHEAD OF THE COLD FRONT. THE BEST CHANCE FOR SOME EARLY SUNSHINE WHERE FORECAST SBCAPE VALUES COULD REACH 1500-2500 J/KG...IS FROM AROUND THE ALBANY AND SARATOGA REGIONS SOUTH AND EAST. FLOW ALOFT WILL STEADILY INCREASE THROUGH THE AFTERNOON...WHICH WILL ALLOW THE SHEAR TO STRENGTHEN AS WELL. DEEP LAYER SHEAR OF 25-35 KT AND THE APPROACHING COLD FRONT WILL LIKELY ALLOW FOR ORGANIZED CLUSTERS/BOWS TO DEVELOP...WITH DAMAGING WINDS THE MAIN THREAT AS FAIRLY WEAK MID-LEVEL LAPSE RATES SHOULD PRECLUDE A HAIL THREAT. EFFICIENT DOWNPOURS WILL ALSO BE POSSIBLE WITH ANY STORMS. HOWEVER...GIVEN THE INCREASING FLOW AND RECENT DRY GROUND CONDITIONS...WE ARE NOT EXPECTING HYDRO RELATED PROBLEMS EXCEPT FOR ISOLATED MINOR URBAN/POOR DRAINAGE FLOODING POSSIBLE. BASED ON TIMING FROM THE 12Z GUIDANCE SUITE AND LOCAL HI RES WRF...TIMING FOR CONVECTION LOOKS TO BE LATE MORNING TO EARLY AFTERNOON FOR AREAS NORTH AND WEST OF THE CAPITAL REGION...MID TO LATE AFTERNOON FOR THE CAPITAL REGION...SARATOGA REGION...SOUTHERN VERMONT AND THE CATSKILLS...AND LATE AFTERNOON TO EARLY EVENING FOR THE MID HUDSON VALLEY...TACONICS AND BERKSHIRES/LITCHFIELD HILLS. DUE TO THE TIMING...BEST CHANCES FOR SEVERE STORMS WILL BE FROM CENTRAL MOHAWK VALLEY AND SARATOGA REGION SOUTH AND EAST. THIS INCLUDES THE GREATER CAPITAL DISTRICT AND ALL POINTS SOUTH AND EAST. WILL CONTINUE TO MENTION POTENTIAL FOR DAMAGING WINDS IN THE HWO FOR THESE AREAS. DUE TO THE COLD FRONT FRONT CROSSING THE REGION...MAXIMUM TEMPERATURES WILL RANGE FROM LOWER TO MID 70S ACROSS THE ADIRONDACKS...TO LOWER TO MID 80S FROM ALBANY SOUTH AND EAST. IT WILL REMAIN HUMID FOR MUCH OF THE AREA FOR MOST OF THE DAY...WITH DEWPOINTS SPIKING IN THE UPPER 60S TO LOWER 70S. ANY LINES OF CONVECTION SHOULD BE EAST OF THE AREA BY DARK...WHICH WILL END THE SEVERE THREAT. JUST A FEW LINGERING SHOWERS WILL BE POSSIBLE FOR THE REST OF THE EVENING...ESPECIALLY ACROSS SOUTHERN AREAS. COOLER AND DRIER AIR WILL FILTER INTO THE REGION OVERNIGHT WITH A NORTHWEST BREEZE. TEMPERATURES WILL BE NOTICEABLY COOLER BY EARLY SUNDAY MORNING. DRY WEATHER AND SEASONABLY COOLER TEMPERATURES ALONG WITH PLENTY OF SUNSHINE EXPECTED FOR SUNDAY AND MONDAY...AS HIGH PRESSURE BUILDS EASTWARD AND SETTLES ACROSS THE NORTHEAST CONUS. HUMIDITY LEVELS WILL BE QUITE COMFORTABLE...WITH COOL NIGHT TIME TEMPERATURES. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... MONDAY NIGHT INTO TUESDAY...MOST OF THE REGION WILL SEE TRANQUIL CONDITIONS WITH AVERAGE TEMPERATURES ACROSS THE REGION. 05/12Z MODEL AND NUMERICAL GUIDANCE DOES SHOW A WEAK LOW PRESSURE SYSTEM WITH TROPICAL ORIGINS MOVING SLOWLY UP THE EAST COAST. MOST OF THE REGION NORTH OF THE LOWER MID HUDSON VALLEY WILL BE FAR ENOUGH REMOVED FROM THE TRACK OF THIS COASTAL LOW. THIS WILL BRING SCATTERED CLOUD COVER TO THE REGION BUT MOST REGIONS WILL REMAIN DRY WITH THE EXCEPTION OF ISOLATED POPS ACROSS OUR FAR SOUTHEASTERN AREAS CLOSER TO THE CENTER OF THE COASTAL LOW PRESSURE SYSTEM. HIGH TEMPERATURES ON TUESDAY WILL RANGE FROM THE UPPER 60S IN THE HIGH TERRAIN TO LOWER AND MID 70S ACROSS VALLEY LOCATIONS. TUESDAY NIGHT THROUGH FRIDAY...OUR NEXT WEATHER SYSTEM WILL BE MAKING ITS WAY INTO THE REGION. MOST 12Z MODELS SHOW HIGHER PROBABILITIES OF PRECIPITATION AS WE GO FROM THURSDAY INTO THURSDAY EVENING. AS AN UPPER LEVEL LOW MOVES EQUATORWARD OUT OF CANADA AS WE GO INTO THE DAY ON WEDNESDAY...A SERIES OF WEAK LOW PRESSURE IMPULSES MOVING NORTHEASTWARD AROUND A BROAD 500 HPA CIRCULATION OVER THE UPPER MIDWEST WILL PROVIDE ISOLATED TO SCATTERED SHOWERS OVER OUR REGION...MAINLY DIURNALLY DRIVEN AS TEMPERATURES BEGIN TO RISE INTO THE MID AND UPPER 70S ON WEDNESDAY WITH DEWPOINT TEMPERATURES ON THE RISE AS WELL WITH A SOUTHERLY FLOW. AS WE GO INTO THE DAY ON THURSDAY...THIS IS WHERE GLOBAL MODELS AND PROBABILISTIC GUIDANCE DIVERGE IN CONFIDENCE FROM EACH OTHER. MODELS RANGE FROM A CONTINUATION ON IMPULSES WHERE A WEAK SURFACE LOW MAY DEVELOP JUST EAST OF OUR REGION THURSDAY AFTERNOON TO A MORE POTENT SURFACE LOW DEVELOPMENT NEAR THE OHIO VALLEY UNDER A FAVORABLE POSITION WITHIN A 100 KT JET STREAK PUTTING OUR REGION IN THE WARM SECTOR FROM AN APPROACHING COLD FRONT AS WE GO INTO THURSDAY EVENING. THIS FORECAST WILL BE UPDATED AS WE GET CLOSER TO THE EVENT AND AS CONFIDENCE INCREASES. HIGH TEMPERATURES ON THURSDAY WILL REMAIN NEAR AVERAGE ON THURSDAY. AS WE APPROACH THE END OF THE WEEK ON FRIDAY...TRANQUIL WEATHER LOOKS TO RETURN TO THE REGION WITH TEMPERATURES SLIGHTLY BELOW AVERAGE WITH A WEST TO NORTHWESTERLY FLOW BEHIND THE PASSING COLD FRONT. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS THIS EVENING WITH A LIGHT WIND AT SPEEDS AROUND 10KTS OR LESS. AS DEWPOINTS ARE RATHER HIGH...NEAR 70F...AND NOCTURNAL COOLING OF THE BOUNDARY LAYER WE SHOULD SEE HAZE/MIST DEVELOP TONIGHT. LATER OVERNIGHT...LOWER LEVEL STRATUS SHOULD RESULT IN MORE MVFR CONDITIONS FOR CIGS/VIS. COULD NOT RULE OUT A PERIOD OF IFR CONDITIONS AT KGFL-KPSF. AS UPSTREAM COLD FRONT APPROACHES...THE PROBABILITIES FOR CONVECTION IMPACTING FLIGHT CONDITIONS INCREASES. WE WILL CONTINUE TO SHOW A GRADUATED APPROACH TO THE POPS WITH INITIALLY PROB30/S THEN TEMPO GROUPS WITH THE DEEPER CONVECTION. WINDS WILL GENERALLY BE FROM THE SOUTHWEST AROUND 10KTS WITH HIGHER GUSTS POSSIBLE IN THE VICINITY OF CONVECTION. OUTLOOK... SATURDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. SUNDAY TO MONDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. TUESDAY TO TUESDAY NIGHT: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. WEDNESDAY: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA. && .FIRE WEATHER... A FLOW OF WARM AND HUMID SOUTHERLY AIR WILL CONTINUE TO RESULT IN ABOVE NORMAL TEMPERATURES INTO SATURDAY. A COLD FRONT APPROACHING FROM THE GREAT LAKES AND SOUTHEAST CANADA WILL CROSS OUR REGION ON SATURDAY...BRINGING SHOWERS AND THUNDERSTORMS. SOME OF THE THUNDERSTORMS MAY BE STRONG TO SEVERE. MUCH COOLER AND DRIER AIR WILL MOVE IN FOR SUNDAY AND MONDAY...AS HIGH PRESSURE BUILDS IN FROM THE WEST. RELATIVE HUMIDITY VALUES WILL INCREASE TO AROUND 90 TO 100 PERCENT TONIGHT...THEN DROP TO MINIMUM VALUES OF BETWEEN 55 AND 65 PERCENT SATURDAY AFTERNOON. MAXIMUM RH VALUES SATURDAY NIGHT ARE EXPECTED TO BE AROUND 90 TO 100 PERCENT. WINDS TONIGHT ARE EXPECTED TO BE SOUTHERLY AROUND 5 TO 10 MPH. SOUTHERLY WINDS WILL SHIFT TO THE WEST BEHIND A COLD FRONT SATURDAY AFTERNOON. WINDS WILL BECOME NORTHWESTERLY AROUND 5 TO 10 MPH SATURDAY NIGHT. && .HYDROLOGY... NO WIDESPREAD HYDRO PROBLEMS ARE EXPECTED THROUGH AT LEAST THE NEXT 5 DAYS. SHOWERS AND THUNDERSTORMS WILL DEVELOP AND OVERSPREAD THE AREA FROM NORTHWEST TO SOUTHEAST ON SATURDAY AHEAD OF A COLD FRONT. WHILE BASIN AVERAGE RAINFALL AMOUNTS LOOK TO BE UNDER A HALF INCH...LOCALIZED RAINFALL AMOUNTS OF OVER 2 INCHES ARE POSSIBLE WHICH MAY CAUSE ISOLATED MINOR FLOODING OF URBAN/POOR DRAINAGE AREAS. DRIER WEATHER IS THEN EXPECTED SATURDAY NIGHT THROUGH TUESDAY...AS HIGH PRESSURE ASSOCIATED WITH RELATIVELY COOL AIR SETTLES OVER THE REGION. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...JPV NEAR TERM...BGM/11/JPV SHORT TERM...JPV LONG TERM...IAA/LFM AVIATION...IAA/BGM FIRE WEATHER...JPV HYDROLOGY...11/JPV
AREA FORECAST DISCUSSION
NWS JACKSONVILLE FL
440 AM EDT SAT SEP 6 2014 ...PERIODS OF HEAVY RAINFALL EXPECTED THROUGH MONDAY... .CURRENTLY... EARLY MORNING SURFACE ANALYSIS DEPICTS HIGH PRESSURE (1021 MILLIBARS) COVERING THE WESTERN ATLANTIC NORTH OF THE BAHAMAS. A LOW-LEVEL TROUGH EXTENDS FROM THE GEORGIA COASTAL WATERS SOUTHWESTWARD TO THE NORTHEAST GULF OF MEXICO. MEANWHILE...A COLD FRONT IS PRESSING ACROSS THE GREAT LAKES STATES AND IS MOVING INTO THE OHIO AND WESTERN PORTIONS OF THE TENNESSEE VALLEY REGION. ALOFT...DEEP- LAYERED RIDGING IS CENTERED OFF THE CAROLINA COASTLINE. LOW-TOPPED CONVECTION IS DEVELOPING ALONG THE LOW- LEVEL TROUGH OVER THE OKEFENOKEE SWAMP AND THE SUWANNEE VALLEY...WITH ISOLATED SHOWERS POPPING OVER THE REST OF NORTHEAST FLORIDA. WITH WEAK STEERING FLOW IN PLACE...THIS ACTIVITY IS MOVING VERY SLOWLY EASTWARD AND IS PRODUCING HEAVY RAINFALL RATES...WHICH WILL LIKELY BE THE THEME FOR THE WEEKEND. OTHERWISE...LOW CEILINGS AND ABUNDANT MID AND UPPER LEVEL CLOUDS ARE BLANKETING MUCH OF THE REGION...WITH PATCHES OF FOG OVER INTERIOR SOUTHEAST GA. TEMPERATURES AND DEWPOINTS AT 08Z WERE GENERALLY IN THE LOW TO MID 70S REGION-WIDE. .NEAR TERM (TODAY AND TONIGHT)... SHORT-TERM HI-RESOLUTION GUIDANCE SUCH AS THE HRRR AND ARW HAVE INITIALIZED WELL WITH RESPECT TO CONVECTIVE DEVELOPMENT IN THE OKEFENOKEE/SUWANNEE VALLEY REGION...AND THESE MODELS ADVECT THIS ACTIVITY INTO THE REMAINDER OF NORTHEAST AND NORTH CENTRAL FL DURING THE REMAINDER OF THE MORNING HOURS. CYCLONIC FLOW IN THE LOW LEVELS WILL CONTINUE TO PROVIDE ENOUGH FORCING FOR BANDS OF SHOWERS AND THUNDERSTORMS TO DEVELOP INTO THE EVENING HOURS...WITH ACTIVITY INCREASING IN COVERAGE ALONG THE I-95 CORRIDOR DURING THE LATE AFTERNOON AND EARLY EVENING HOURS...WHERE CATEGORICAL POPS WERE USED IN THE FORECAST GRIDS. INSERTED HEAVY RAINFALL WORDING INTO THE ZONES FOR THESE LOCATIONS...AND WIDESPREAD RAINFALL TOTALS TODAY AROUND 1 INCH ARE EXPECT. THE SCATTERED NATURE OF THE HEAVY DOWNPOURS ON FRIDAY WILL PRECLUDE THE NEED FOR A FLOOD WATCH AT THIS TIME. SLIGHT COOLING ALOFT SHOULD ALSO AID IN THE DEVELOPMENT OF NUMEROUS MAINLY AFTERNOON AND EARLY EVENING SHOWERS AND THUNDERSTORMS ACROSS THE REMAINDER OF INTERIOR SOUTHEAST GA. AN EARLY START TO CONVECTION WILL LIKELY KEEP HIGHS IN THE MID TO UPPER 80S REGION-WIDE...WITH LOCATIONS NEAR THE ALTAMAHA POSSIBLY APPROACHING 90 BEFORE AFTERNOON CONVECTION DEVELOPS. LOW PRESSURE IS EXPECTED TO CONSOLIDATE ALONG THE GA COAST THIS EVENING...INCREASING SOUTHWEST STEERING FLOW IN THE LOW LEVELS. THIS PATTERN WILL LIKELY PUSH EVENING ACTIVITY ALONG THE COAST INTO THE OFFSHORE WATERS BY MIDNIGHT...WITH DRYING EXPECTED FROM WEST TO EAST AS THE EVENING PROGRESSES. HI-RES MODELS INDICATE THE POTENTIAL FOR OVERNIGHT DEVELOPMENT IN NORTH CENTRAL FL DURING THE PRE-DAWN HOURS ON SUN. OTHERWISE...EXPECT ANOTHER ROUND OF LOW CIGS AND SOME PATCHY FOG ACROSS INTERIOR SOUTHEAST GA. WARM AND HUMID CONDITIONS WILL KEEP LOWS IN THE 70S. .SHORT TERM (SUNDAY THROUGH TUESDAY)... SUN & MON...UNSETTLED WEATHER WITH ABOVE NORMAL RAIN CHANCES WILL CONTINUE AS HIGH MOISTURE CONTENT LINGERS OVER THE AREA (PWATS OVER 2 INCHES) AND COMBINES WITH FORCING TRAILING A 1000-700 MB LOW AS IT TRACKS SLOWLY NORTHWARD ALONG THE SE ATLANTIC SEABOARD. SUN PRECIP WILL LIKELY BE ONGOING EARLY IN THE DAY ALONG A CONVERGENT ZONE DRIFTING SOUTHWARD OVER THE AREA AS THE SURFACE LOW TRACKS NNE ALONG THE GA/SC COAST...BUT MODELS DIVERGE WHERE THIS ZONE WILL POSITION AROUND 12Z SUN WITH THE NMM/NAM NEAR THE FL/GA STATE LINE AND THE ARW OVER OUR SOUTHERN FL ZONES. THE GFS IS MUCH LESS AGGRESSIVE AND KEEPS THE HIGHER POPS OFFSHORE OF THE LOCAL ATLANTIC COAST. FOR NOW ADVERTISED 20-30% POPS THROUGH SUNRISE SUN...BUT AS MODEL CONSENSUS REFINES ITSELF THERE IS A HIGH POTENTIAL FOR A BAND OF LOCALLY HEAVY RAINFALL ACROSS SOME PORTION OF THE FORECAST AREA EARLY SUNDAY MORNING. AS THE DAY PROGRESSES AND FORCING FROM A WEAK MID LEVEL TROUGH APPROACHES FROM THE NW...ADDITIONAL PRECIP WILL BLOSSOM ACROSS THE FORECAST AREA...WITH AGAIN A DIURNAL PATTERN EXPECTED WITH A FADE IN ACTIVITY AFTER SUNSET. ADVERTISED WIDESPREAD RAINFALL CHANCES OF 60-70% WITH THE GREATEST POTENTIAL IN THE AFTN/EVENING. THE MAIN CONVECTIVE HAZARDS WILL CONTINUE TO BE LOCALLY HEAVY RAINFALL GIVEN SLOW STORM MOTION...EXCESSIVE LIGHTNING AND WET DOWNBURSTS OF 40-50 MPH. MON ANOTHER ROUND OF SHOWERS/TSTORMS EXPECTED TO FILL IN ACROSS THE AREA THROUGH THE DAY WITH A MORE EASTWARD PUSH OF PRECIP INTO THE AFTN TOWARD THE ATLANTIC SEABOARD. HIGH TEMPS WILL BE NEAR TO SLIGHTLY BELOW CLIMO IN THE MID/UPPER 80S...NEAR 90 SE GA...WITH LOWS MILD IN THE LOW/MID 70S POSSIBLY A FEW UPPER 60S WELL INLAND MON NIGHT AS DRIER AIR BEGINS TO FILTER IN FROM THE WEST. TUE...RAIN CHANCES DECREASE AS LOW PRESSURE DEPARTS TO THE NE AND HIGH PRESSURE RIDGING BUILDS NORTHWARD FROM SOUTH FL. PWATS HOVER NEAR 2 INCHES OVER NE FL...BUT DRIER AIR WITH PWATS FALLING NEAR 1.75 INCHES FILTERS IN OVER SE GA. STILL ENOUGH LINGERING DEEP LAYER MOISTURE TO CONTINUE ELEVATED RAIN CHANCES N THE 40-50% RANGE WITH LIGHT STEERING FLOW STILL SUPPORTING LOCALLY HEAVY RAINFALL. AFTN/EVENING PRECIP WILL SHIFT FROM THE ATLANTIC COAST MON TOWARD WEST OF HIGHWAY 301 TUE AS THE EAST COAST SEA BREEZE BEGINS TO STRENGTHEN ITS INLAND PUSH AS THE RIDGE BUILDS IN FROM THE SOUTH. .LONG TERM (WEDNESDAY THROUGH SATURDAY)... MEAN 1000-500 MB RIDGING WILL EDGE NORTHWARD AND EXTEND ACROSS N-CENTRAL FL WHICH WILL BRING RAIN CHANCES BACK DOWN TO NEAR TO BELOW CLIMO VALUES GIVEN INCREASED SUBSIDENCE. ADVERTISED RAIN CHANCES IN THE 25-40% RANGE WITH THE HIGHEST VALUES OVER INLAND AREAS BETWEEN THE ST JOHNS RIVER BASIN AND THE I-75 CORRIDOR EACH AFTN/EVENING GIVEN WEAK STEERING FLOW. TEMPS WILL MODERATE NEAR TO ABOVE CLIMO VALUES GIVEN STACKED RIDGING OVER THE AREA WITH HIGHS IN THE LOW 90S/UPPER 80S INLAND TO MID 80S COAST...WITH LOWS IN THE 70S. NEXT WEEKEND A FRONTAL ZONE BEGINS TO STALL OVER SOUTH GA...WHICH WILL BRING AN INCREASE IN RAIN CHANCES NEXT WEEKEND. && .AVIATION... LIFR CIGS AT GNV WILL LIKELY LIFT SOON AS SHOWER ACTIVITY APPROACHES THE TERMINAL. IFR CIGS AROUND 800 FEET ARE EXPECTED AT SSI THROUGH AROUND 13Z...WITH VFR CIGS AROUND 5000 FT ELSEWHERE THROUGH SUNRISE. NUMEROUS SHOWERS AND EMBEDDED THUNDERSTORMS ARE EXPECTED TO MOVE OVER THE REGIONAL TERMINALS AFTER 14Z...AND HAVE RECENTLY AMENED THE TAFS TO INCLUDE TEMPO GROUPS FOR PERIODS OF IFR VISIBILITIES THROUGH AT LEAST 18Z. PERIODS OF SUB-VFR CONDITIONS WILL REMAIN POSSIBLE AT THE REGIONAL TERMINALS THROUGH 00Z...WITH SOUTH TO SOUTHWEST SURFACE WINDS REMAINING NEAR OR BELOW 10 KNOTS OUTSIDE OF HEAVIER SHOWER AND THUNDERSTORM ACTIVITY. && .MARINE... WEAK LOW PRESSURE WILL REMAIN OVER OUR REGION THIS WEEKEND...WITH PERIODS OF NUMEROUS SHOWERS AND THUNDERSTORMS MOVING INTO AND DEVELOPING OVER THE COASTAL WATERS THROUGH MONDAY. OUTSIDE OF THUNDERSTORM ACTIVITY...SOUTHWEST WINDS WILL LIKELY SURGE TO NEAR CAUTION CONDITIONS OVER THE COASTAL WATERS THIS EVENING. A COLD FRONT WILL THEN PUSH INTO THE SOUTHEASTERN STATES LATE IN THE WEEKEND...STALLING NEAR THE SOUTHEAST GEORGIA COAST EARLY NEXT WEEK. SEAS WILL GENERALLY REMAIN IN THE 2 TO 4 FOOT RANGE THROUGH MONDAY. HIGH PRESSURE WILL THEN BUILD FROM SOUTH TO NORTH TOWARDS MIDWEEK...ALLOWING A GENERAL SOUTHERLY WIND PATTERN WITH SPEEDS REMAINING BELOW 15 MPH. RIP CURRENTS: LOW RISK EXPECTED THROUGH SUNDAY. && .PRELIMINARY POINT TEMPS/POPS... AMG 89 73 90 73 / 60 60 70 60 SSI 84 75 86 74 / 80 80 60 60 JAX 87 74 89 73 / 80 80 70 60 SGJ 87 75 86 74 / 80 80 60 60 GNV 87 72 87 71 / 70 70 60 40 OCF 89 72 86 72 / 70 60 60 40 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...NONE. GA...NONE. AM...NONE. && $$ NELSON/ENYEDI
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
300 AM CDT SAT SEP 6 2014 .DISCUSSION... 836 PM CDT CONVECTION HAS PUSHED SOUTHEAST OF THE AREA...WITH JUST A FEW LINGERING SHOWERS SLIDING EAST ACROSS NORTHERN IL THIS EVENING. BROAD SFC RIDGE WILL CONTINUE TO SLIDE EAST OVERNIGHT...WHICH WILL HELP PROVIDE A STEADY DRYING TREND OVERNIGHT. SOME LINGERING SHOWERS OVERNIGHT MAY SKIRT OUR FAR SOUTHEAST CWFA. TEMPS WILL CONTINUE TO COOL INTO THE MID/UPR 50S GENERALLY NORTH OF I-80...AND SOUTH OF THIS TEMPS SHUD COOL TO ARND 60. BEACHLER //PREV DISCUSSION... 1142 AM CDT COLD FRONT IS MOVING THROUGH NORTHWESTERN PORTIONS OF THE CWA LATE THIS MORNING AND SHOULD CONTINUE TO MAKE STEADY PROGRESS SOUTHEAST ACROSS THE AREA THIS AFTERNOON. DEVELOPING PRESSURE FALLS OVER IOWA IN ADVANCE OF SHORTWAVE TROUGH OVER NE KS/SE NE WILL PROBABLY RESULT IN FRONT SLOWING DOWN A BIT THIS AFTERNOON. GOES EAST IS IN RAPID SCAN MODE THIS AFTERNOON AND IS NICELY SHOWING SOME ENHANCEMENT TO THE CUMULUS FIELD RIGHT ALONG THE IMMEDIATE FRONTAL BOUNDARY. IN GENERAL THE CUMULUS FIELD ON SATELLITE AND OUT THE WINDOW LOOKS VERY MUSHY AND LACKING VERTICAL GROWTH...LIKELY DUE IN LARGE PART TO THE VERY FORMIDABLE CAP EVIDENT ON DVN/ILX MORNING SOUNDINGS AND STILL PRESENT IN RECENT ACARS SOUNDINGS OUT OF ORD AND MDW. CONTINUED HEATING AND DESTABILIZATION OF THE BOUNDARY LAYER ALONG WITH FORCED ASCENT ALONG THE FRONT SHOULD EVENTUALLY CAUSE CAP TO BUST...BUT LIKELY NOT UNTIL THE FRONT IS AT LEAST TO A CHICAGO TO PERU LINE IF NOT FARTHER SOUTHEAST. WILL BE REWORKING POP GRIDS TO BETTER REFLECT THIS LINE OF THINKING...INCLUDING VERY LITTLE THREAT OF PRECIP OVER NORTHWEST CWA AND STEADILY DECREASING CHANCE FROM THE NORTHWEST SPREADING ACROSS THE AREA THIS AFTERNOON. POST FRONT RAIN STILL A DISTINCT POSSIBILITY THIS EVENING INTO TONIGHT AS AFOREMENTIONED KS/NE SHORTWAVE TRACKS NORTHEAST INTO THE REGION. IZZI .MEDIUM AND LONG TERM DISCUSSION... 305 PM CDT... FOR THE REMAINDER OF THE SHORT TERM...SATURDAY AND SUNDAY...THE SURFACE COLD FRONT SHOULD PUSH SOUTHEAST OF THE CWA THROUGH THE OHIO VALLEY. HOWEVER...GIVEN THAT THE BULK OF THE PCPN SHOULD BE ALONG AND BEHIND THE BOUNDARY...THERE WILL LIKELY BE SOME LINGERING SHOWERS AND PERHAPS AN ISOLATED THUNDERSTORM OVER THE FAR SOUTHEASTERN PORTION OF THE CWA...MAINLY AROUND BENTON COUNTY... INDIANA. THROUGH THE DAY ON SATURDAY...HIGH PRESSURE WILL SPREAD FROM THE CENTRAL PLAINS...ACROSS THE MIDDLE MISSISSIPPI VALLEY AND INTO THE MIDWEST. FOLLOWING THE FROPA AND AS THE HIGH SPREADS ACROSS THE REGION...MOISTURE WILL DIMINISH MARKEDLY...WITH DEWPOINTS DROPPING THROUGH THE 50S ON SATURDAY AND EVEN INTO THE UPPER 40S BY SUNDAY. TEMPERATURES ON SATURDAY WILL BE AT LEAST 10 DEGREES LOWER THAN ON FRIDAY...ONLY IN THE LOWER 70S. UNDER FULL SUNSHINE AND WITH LOW DEWPOINTS...TEMPERATURES ON SUNDAY SHOULD BE ABLE TO REBOUND BACK INTO THE MIDDLE TO UPPER 70S. SO AFTER A LITTLE PCPN OVER THE FAR SERN PORTION OF THE CWA SATURDAY MORNING...THE REMAINDER OF THE WEEKEND SHOULD BE QUITE PLEASANT. FOR THE LONGER TERM...FROM MONDAY THROUGH FRIDAY...EXPECT MONDAY TO START OUT COOL AND DRY WITH LOWS IN THE LOWER 50S. HOWEVER... ANOTHER SYSTEM IS EXPECTED TO TAKE SHAPE OVER THE CENTRAL PLAINS. AS THE HIGH SHIFTS OFF TO THE EAST AND LOW PRESSURE DEVELOPS OVER THE PLAINS...A RETURN FLOW OF MOISTURE WILL SET UP. THROUGH THE DAY...INCREASING WARM/MOIST ADVECTION WILL INCREASE AS A WARM FRONT ALSO LIFTS NORTH TROUGH THE REGION. EXPECT THAT THE NEXT ROUND OF PCPN SHOULD SPREAD INTO THE WRN PORTIONS OF THE CWA BY MONDAY EVENING AND CONTINUE TO SPREAD EAST ACROSS THE REMAINDER OF THE CWA THROUGH MONDAY NIGHT AND INTO TUESDAY MORNING. THE FORECAST PICTURE BECOMES A BIT MORE MUDDLED INTO MID WEEK AS THE LARGER SCALE MODELS BEGIN TO DIVERGE IN THEIR SOLUTIONS...WHICH WILL HAVE A BIG IMPACT ON THE SENSIBLE WEATHER FORECAST. THE ECMWF WANTS TO DEVELOP A DEEPER LOW IN ASSOCIATION WITH A NRN STREAM SHORT WAVE WHILE THE GFS IS QUICKER AND WEAKER. SINCE THE UPPER LEVEL PATTERN IS EXPECTED TO REMAIN VERY CLOSE TO ZONAL...WITH AN UPPER RIDGE ACROSS THE SRN CONUS ANS AND VERY BROAD TROUGHING OVER THE NRN CONUS...AND THE FASTER WLYS ACROSS THE NRN PLAINS/GREAT LAKES REGION...HAVE TRENDED CLOSER TO THE FASTER GFS SOLUTION AS THE ZONAL FLOW PATTERN ALOFT WOULD FAVOR A FASTER SOLUTION. HOWEVER...THE CAVEAT HERE IS THAT IN FAST...ZONAL FLOW...FORECAST ERRORS CAN MAGNIFY QUICKLY... PARTICULARLY IN THE TIMING OF THE SYSTEM...SO...EVEN THOUGH A FASTER SOLUTION WOULD MAKE SENSE...THE TIMING UNCERTAINTIES ASSOCIATED WITH FAST ZONAL FLOW ALOFT INTRODUCES LOWER CONFIDENCE IN THE END PRODUCTS. BY FRIDAY...AT THE END OF THE FORECAST PERIOD...THE LONGER RANGE MODELS WANT TO CARVE OUT A SHARPER TROUGH ALOFT AND BRING MUCH COOLER AIR INTO THE REGION. THE GFS IS ADVERTISING HIGH TEMPS ON FRIDAY ONLY IN THE LOWER TO MIDDLE 50S. THE OLD 00Z RUN OF THE ECMWF HAD ALSO BEEN INDICATING HIGHS ON FRIDAY ONLY IN THE LOWER TO MIDDLE 50S...BUT THE NEW 12Z HAS BACKED OFF ON THIS A BIT AND IS NOW INDICATING HIGHS IN THE UPPER 50S TO LOWER 60S. AT THAT TIME RANGE...THE MOS BASED PRODUCTS ARE LIKELY TRENDING TOO CLOSE TO CLIMATOLOGY...WITH HIGHS IN THE MIDDLE TO UPPER 60S. SO...HAVE TRENDED THE FORECAST MAX TEMPS FOR NEXT FRIDAY IN THE LOWER 60S...BUT IT WILL BE INTERESTING TO SEE HOW THIS PLAYS OUT AND IF THE REGIONS SEES THE FIRST SHOT OF AUTUMNAL WEATHER. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * PATCHY MVFR CIGS IN 2500-3000 FT RANGE PRIOR TO SUNRISE. * NORTHWEST WINDS LESS THAN 10 KT BECOMING NORTHEAST LATE THIS AFTERNOON WITH LAKE BREEZE. RATZER //DISCUSSION...UPDATED 06Z... COLD FRONT HAS PUSHED WELL SOUTHEAST OF TERMINALS AS OF MIDNIGHT WITH SHOWERS HAVING ALSO GENERALLY ALONG/SOUTHEAST OF A KSPI-KIKK- KSBN LINE AT 06Z. LOWER VFR CIGS IN THE 3500-6000 FT RANGE LINGER ACROSS CHICAGO AREA...WITH SOME PATCHY SCT/BKN MVFR IN THE 2000-3000 FT RANGE ALSO NOTED ACROSS THE CITY (KORD-KMDW-KGYY). FORECAST SOUNDINGS CONTINUE TO INDICATE SLOW BUT STEADY DRY ADVECTION ON LIGHT NORTHWEST WINDS...WITH DRYING RESULTING IN EROSION OF MVFR LEVEL CLOUDS PRIOR TO SUNRISE. CONTINUED DRYING OF THE COLUMN AFTER SUNRISE IS EXPECTED TO YIELD VFR CONDITIONS THROUGH REMAINDER OF FORECAST. HIGH PRESSURE RIDGE AXIS BUILDS SOUTHEAST FROM WISCONSIN THIS AFTERNOON WITH WEAKER GRADIENT EXPECTED TO SUPPORT A SHIFT FROM LIGHT NORTH-NORTHWEST OR NORTH WINDS TO NORTHEAST WINDS AS A LAKE BREEZE DEVELOPS LATE THIS AFTERNOON OR BY EVENING. HIGH-RES MODEL WINDS DEPICT THIS MORE FULLY FOR KGYY AND KMDW...WITH A LITTLE LESS CONFIDENCE OF INLAND PUSH AT KORD...THOUGH A WEAKENING NORTH GRADIENT TYPICALLY SUPPORTS SUCH A LAKE BREEZE PUSH. IN ANY CASE PREVAILING WINDS SHOULD BE UNDER 10 KT...DECREASING TO LESS THAN 5 KT AND BECOMING WEST-SOUTHWEST AFTER SUNSET. RATZER //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM CONFIDENCE IN TIMING SHIFT TO NORTHEAST WINDS WITH LAKE BREEZE. * HIGH CONFIDENCE ALL OTHER FORECAST ELEMENTS. RATZER //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY THROUGH MONDAY...VFR. TUESDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS. BMD && .MARINE... 259 AM CDT HIGH PRESSURE OVER THE CENTRAL PLAINS WILL MOVE SLOWLY EAST INTO THE MIDWEST TONIGHT AND ACROSS THE LOWER LAKES BY SUNDAY NIGHT. BRIEF PERIOD OF GUSTY NORTH-NORTHWEST WINDS TO 25 KT THIS MORNING AS THE SURFACE HIGH DEVELOPS TOWARD THE LAKE SHOULD RELAX THIS AFTERNOON ESPECIALLY ON SOUTHERN LAKE MICHIGAN WHERE THE RIDGE AXIS WILL RESIDE BY EVENING. FARTHER NORTH...A WEAK LOW WILL PASS ACROSS THE NORTHERN LAKES TONIGHT...BACKING WINDS MORE WESTERLY WITH GUSTS 20-25 KT AGAIN AHEAD OF A WEAK COLD FRONT THIS AFTERNOON...THEN VEERING NORTH TOWARD EVENING AND DIMINISHING. WINDS WILL COME BACK AROUND TO THE SOUTH-SOUTHEAST SUNDAY AND SUNDAY NIGHT AS THE HIGH DRIFTS OFF TO THE EAST ACROSS THE LOWER LAKES INTO NEW ENGLAND. WINDS LOOK TO REMAIN FAIRLY MODEST FROM THE SOUTH EARLY IN THE WEEK WHILE LOW PRESSURE DEVELOPS OVER THE PLAINS. THIS LOW IS EXPECTED TO DEEPEN AND EVENTUALLY TRACK TOWARD THE WESTERN LAKES BY MID-WEEK. THE EXACT TRACK REMAINS A LITTLE UNCERTAIN AT THIS POINT...THOUGH MOST MODEL GUIDANCE BRINGS THE LOW ACROSS IOWA INTO WISCONSIN OR NORTHERN ILLINOIS ON WEDNESDAY...BEFORE SOLUTIONS DIVERGE. IN EITHER CASE...WINDS ARE EXPECTED TO BACK SOUTHEAST-EAST AND INCREASE AS THE GRADIENT TIGHTENS UP IN ADVANCE OF THE LOW TUESDAY NIGHT INTO EARLY WEDNESDAY. NORTH-NORTHWEST WINDS AROUND 20 KT THIS MORNING PRODUCING 4-5 FOOTERS AT BUOYS ALONG THE SOUTH/SOUTHEAST SHORE. SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT THROUGH THIS AFTERNOON FOR THE INDIANA NEARSHORE WATERS. WINDS DIMINISH AND BACK QUICKLY TOWARD EVENING WHICH SHOULD ALLOW WAVES TO SUBSIDE FAIRLY QUICKLY BY EVENING. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 7 PM SATURDAY. LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 7 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
  [top] Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 259 AM CDT Sat Sep 6 2014 .SHORT TERM...(Today) ISSUED AT 259 AM CDT SAT SEP 6 2014 Despite passage of a cold front during the evening hours, scattered light showers persist across the southern two-thirds of the KILX CWA early this morning. NAM/GFS/ECMWF have all verified too far north with lingering precip field at 06z, while the latest HRRR seems to have the best handle on the current situation. Following the latest radar trends and HRRR solution, have maintained low chance PoPs along/south of I-70 into the early afternoon before showers gradually push further southward into the Ohio River Valley. Meanwhile further north, have gone with a dry forecast across the remainder of the CWA. Skies will start out mostly cloudy, followed by a steady clearing trend from north to south as the day progresses. Afternoon high temperatures will be quite a bit cooler than yesterday, with readings remaining in the lower to middle 70s. && .LONG TERM...(Tonight through Friday) ISSUED AT 259 AM CDT SAT SEP 6 2014 High pressure will build into the region tonight into Sunday, resulting in clear skies and cool temperatures. Light winds/dry airmass will allow excellent radiational cooling to take place tonight, with lows bottoming out in the lower to middle 50s. On the flip side, full sunshine acting on the dry airmass will help temperatures rebound nicely into the middle to upper 70s on Sunday. Once the upper trough responsible for the cool weather lifts into eastern Canada, an active zonal flow pattern will develop across the CONUS next week. Two distinct systems will track through this flow, bringing rain chances to central Illinois. The first is progged to track from the Northern Plains Sunday night into the southern Great Lakes by Tuesday morning. Models are developing showers/storms in advance of this feature Monday night as low-level jet focuses across northern Missouri/southern Iowa. Solutions vary as to how far east into the prevailing surface ridge axis precip will penetrate late Monday night into Tuesday. Given presence of very dry airmass initially and only weak upper support with the short-wave, will keep highest PoPs confined to the Illinois River Valley Monday night. Further east, will go with a dry forecast along/east of I-57. Will only mention low chance PoPs on Tuesday as nocturnal convection undergoes diurnal weakening further eastward into the dry airmass. Second stronger wave will approach Tuesday night into Wednesday, bringing a much better chance for widespread rain. Models are suggesting moisture from tropical system in the Pacific may get drawn into this feature, resulting in unseasonably high precipitable water values in excess of 2 inches. GFS/ECMWF/GEM all bring a hefty slug of precip into Illinois late Tuesday night into Wednesday accordingly: however, axis of heaviest precip still remains in question. Have boosted PoPs to likely across the northern two-thirds of the CWA Tuesday night and Wednesday. Initial QPF from WPC indicates the potential for 1 to 2 inches of rain across much of the area during this time, with the highest amounts across the Illinois River Valley. Once wave passes to the east, strong cold front will settle southward, taking the higher rain chances into the far southern CWA Wednesday night. After that, most model guidance is advertising a cooler/drier day on Thursday followed by a shot of even cooler air by the end of the week. Both the GFS and ECMWF show 850mb temps dropping to around 0c by next Saturday morning, potentially resulting in highs only in the middle to upper 60s and lows dipping into the 40s next weekend. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 1157 PM CDT FRI SEP 5 2014 All sites should be VFR next 24hrs, except for during the 2hr TEMPO group as the front and pcpn comes through the sites. The front should come through PIA around 21z, SPI and BMI around 22Z, DEC around 23z, and CMI around 00z. Will start with VCTS and then have a the TEMPO group for 2hrs following. Once the front comes through, models have a wave coming through that keeps showers around the area during the evening hours. During the TEMPO period, vis with the thunderstorms could drop to around 3sm. Cigs should probably stay above 3kft. Winds will be south to southwest through most of the period, but when the front comes through, winds will switch to west-northwest and then northerly during the evening hours. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...BARNES LONG TERM...BARNES AVIATION...BARKER
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1237 AM CDT SAT SEP 6 2014 .DISCUSSION... 836 PM CDT CONVECTION HAS PUSHED SOUTHEAST OF THE AREA...WITH JUST A FEW LINGERING SHOWERS SLIDING EAST ACROSS NORTHERN IL THIS EVENING. BROAD SFC RIDGE WILL CONTINUE TO SLIDE EAST OVERNIGHT...WHICH WILL HELP PROVIDE A STEADY DRYING TREND OVERNIGHT. SOME LINGERING SHOWERS OVERNIGHT MAY SKIRT OUR FAR SOUTHEAST CWFA. TEMPS WILL CONTINUE TO COOL INTO THE MID/UPR 50S GENERALLY NORTH OF I-80...AND SOUTH OF THIS TEMPS SHUD COOL TO ARND 60. BEACHLER //PREV DISCUSSION... 1142 AM CDT COLD FRONT IS MOVING THROUGH NORTHWESTERN PORTIONS OF THE CWA LATE THIS MORNING AND SHOULD CONTINUE TO MAKE STEADY PROGRESS SOUTHEAST ACROSS THE AREA THIS AFTERNOON. DEVELOPING PRESSURE FALLS OVER IOWA IN ADVANCE OF SHORTWAVE TROUGH OVER NE KS/SE NE WILL PROBABLY RESULT IN FRONT SLOWING DOWN A BIT THIS AFTERNOON. GOES EAST IS IN RAPID SCAN MODE THIS AFTERNOON AND IS NICELY SHOWING SOME ENHANCEMENT TO THE CUMULUS FIELD RIGHT ALONG THE IMMEDIATE FRONTAL BOUNDARY. IN GENERAL THE CUMULUS FIELD ON SATELLITE AND OUT THE WINDOW LOOKS VERY MUSHY AND LACKING VERTICAL GROWTH...LIKELY DUE IN LARGE PART TO THE VERY FORMIDABLE CAP EVIDENT ON DVN/ILX MORNING SOUNDINGS AND STILL PRESENT IN RECENT ACARS SOUNDINGS OUT OF ORD AND MDW. CONTINUED HEATING AND DESTABILIZATION OF THE BOUNDARY LAYER ALONG WITH FORCED ASCENT ALONG THE FRONT SHOULD EVENTUALLY CAUSE CAP TO BUST...BUT LIKELY NOT UNTIL THE FRONT IS AT LEAST TO A CHICAGO TO PERU LINE IF NOT FARTHER SOUTHEAST. WILL BE REWORKING POP GRIDS TO BETTER REFLECT THIS LINE OF THINKING...INCLUDING VERY LITTLE THREAT OF PRECIP OVER NORTHWEST CWA AND STEADILY DECREASING CHANCE FROM THE NORTHWEST SPREADING ACROSS THE AREA THIS AFTERNOON. POST FRONT RAIN STILL A DISTINCT POSSIBILITY THIS EVENING INTO TONIGHT AS AFOREMENTIONED KS/NE SHORTWAVE TRACKS NORTHEAST INTO THE REGION. IZZI .MEDIUM AND LONG TERM DISCUSSION... 305 PM CDT... FOR THE REMAINDER OF THE SHORT TERM...SATURDAY AND SUNDAY...THE SURFACE COLD FRONT SHOULD PUSH SOUTHEAST OF THE CWA THROUGH THE OHIO VALLEY. HOWEVER...GIVEN THAT THE BULK OF THE PCPN SHOULD BE ALONG AND BEHIND THE BOUNDARY...THERE WILL LIKELY BE SOME LINGERING SHOWERS AND PERHAPS AN ISOLATED THUNDERSTORM OVER THE FAR SOUTHEASTERN PORTION OF THE CWA...MAINLY AROUND BENTON COUNTY... INDIANA. THROUGH THE DAY ON SATURDAY...HIGH PRESSURE WILL SPREAD FROM THE CENTRAL PLAINS...ACROSS THE MIDDLE MISSISSIPPI VALLEY AND INTO THE MIDWEST. FOLLOWING THE FROPA AND AS THE HIGH SPREADS ACROSS THE REGION...MOISTURE WILL DIMINISH MARKEDLY...WITH DEWPOINTS DROPPING THROUGH THE 50S ON SATURDAY AND EVEN INTO THE UPPER 40S BY SUNDAY. TEMPERATURES ON SATURDAY WILL BE AT LEAST 10 DEGREES LOWER THAN ON FRIDAY...ONLY IN THE LOWER 70S. UNDER FULL SUNSHINE AND WITH LOW DEWPOINTS...TEMPERATURES ON SUNDAY SHOULD BE ABLE TO REBOUND BACK INTO THE MIDDLE TO UPPER 70S. SO AFTER A LITTLE PCPN OVER THE FAR SERN PORTION OF THE CWA SATURDAY MORNING...THE REMAINDER OF THE WEEKEND SHOULD BE QUITE PLEASANT. FOR THE LONGER TERM...FROM MONDAY THROUGH FRIDAY...EXPECT MONDAY TO START OUT COOL AND DRY WITH LOWS IN THE LOWER 50S. HOWEVER... ANOTHER SYSTEM IS EXPECTED TO TAKE SHAPE OVER THE CENTRAL PLAINS. AS THE HIGH SHIFTS OFF TO THE EAST AND LOW PRESSURE DEVELOPS OVER THE PLAINS...A RETURN FLOW OF MOISTURE WILL SET UP. THROUGH THE DAY...INCREASING WARM/MOIST ADVECTION WILL INCREASE AS A WARM FRONT ALSO LIFTS NORTH TROUGH THE REGION. EXPECT THAT THE NEXT ROUND OF PCPN SHOULD SPREAD INTO THE WRN PORTIONS OF THE CWA BY MONDAY EVENING AND CONTINUE TO SPREAD EAST ACROSS THE REMAINDER OF THE CWA THROUGH MONDAY NIGHT AND INTO TUESDAY MORNING. THE FORECAST PICTURE BECOMES A BIT MORE MUDDLED INTO MID WEEK AS THE LARGER SCALE MODELS BEGIN TO DIVERGE IN THEIR SOLUTIONS...WHICH WILL HAVE A BIG IMPACT ON THE SENSIBLE WEATHER FORECAST. THE ECMWF WANTS TO DEVELOP A DEEPER LOW IN ASSOCIATION WITH A NRN STREAM SHORT WAVE WHILE THE GFS IS QUICKER AND WEAKER. SINCE THE UPPER LEVEL PATTERN IS EXPECTED TO REMAIN VERY CLOSE TO ZONAL...WITH AN UPPER RIDGE ACROSS THE SRN CONUS ANS AND VERY BROAD TROUGHING OVER THE NRN CONUS...AND THE FASTER WLYS ACROSS THE NRN PLAINS/GREAT LAKES REGION...HAVE TRENDED CLOSER TO THE FASTER GFS SOLUTION AS THE ZONAL FLOW PATTERN ALOFT WOULD FAVOR A FASTER SOLUTION. HOWEVER...THE CAVEAT HERE IS THAT IN FAST...ZONAL FLOW...FORECAST ERRORS CAN MAGNIFY QUICKLY... PARTICULARLY IN THE TIMING OF THE SYSTEM...SO...EVEN THOUGH A FASTER SOLUTION WOULD MAKE SENSE...THE TIMING UNCERTAINTIES ASSOCIATED WITH FAST ZONAL FLOW ALOFT INTRODUCES LOWER CONFIDENCE IN THE END PRODUCTS. BY FRIDAY...AT THE END OF THE FORECAST PERIOD...THE LONGER RANGE MODELS WANT TO CARVE OUT A SHARPER TROUGH ALOFT AND BRING MUCH COOLER AIR INTO THE REGION. THE GFS IS ADVERTISING HIGH TEMPS ON FRIDAY ONLY IN THE LOWER TO MIDDLE 50S. THE OLD 00Z RUN OF THE ECMWF HAD ALSO BEEN INDICATING HIGHS ON FRIDAY ONLY IN THE LOWER TO MIDDLE 50S...BUT THE NEW 12Z HAS BACKED OFF ON THIS A BIT AND IS NOW INDICATING HIGHS IN THE UPPER 50S TO LOWER 60S. AT THAT TIME RANGE...THE MOS BASED PRODUCTS ARE LIKELY TRENDING TOO CLOSE TO CLIMATOLOGY...WITH HIGHS IN THE MIDDLE TO UPPER 60S. SO...HAVE TRENDED THE FORECAST MAX TEMPS FOR NEXT FRIDAY IN THE LOWER 60S...BUT IT WILL BE INTERESTING TO SEE HOW THIS PLAYS OUT AND IF THE REGIONS SEES THE FIRST SHOT OF AUTUMNAL WEATHER. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * PATCHY MVFR CIGS IN 2500-3000 FT RANGE PRIOR TO SUNRISE. * NORTHWEST WINDS LESS THAN 10 KT BECOMING NORTHEAST LATE THIS AFTERNOON WITH LAKE BREEZE. RATZER //DISCUSSION...UPDATED 06Z... COLD FRONT HAS PUSHED WELL SOUTHEAST OF TERMINALS AS OF MIDNIGHT WITH SHOWERS HAVING ALSO GENERALLY ALONG/SOUTHEAST OF A KSPI-KIKK- KSBN LINE AT 06Z. LOWER VFR CIGS IN THE 3500-6000 FT RANGE LINGER ACROSS CHICAGO AREA...WITH SOME PATCHY SCT/BKN MVFR IN THE 2000-3000 FT RANGE ALSO NOTED ACROSS THE CITY (KORD-KMDW-KGYY). FORECAST SOUNDINGS CONTINUE TO INDICATE SLOW BUT STEADY DRY ADVECTION ON LIGHT NORTHWEST WINDS...WITH DRYING RESULTING IN EROSION OF MVFR LEVEL CLOUDS PRIOR TO SUNRISE. CONTINUED DRYING OF THE COLUMN AFTER SUNRISE IS EXPECTED TO YIELD VFR CONDITIONS THROUGH REMAINDER OF FORECAST. HIGH PRESSURE RIDGE AXIS BUILDS SOUTHEAST FROM WISCONSIN THIS AFTERNOON WITH WEAKER GRADIENT EXPECTED TO SUPPORT A SHIFT FROM LIGHT NORTH-NORTHWEST OR NORTH WINDS TO NORTHEAST WINDS AS A LAKE BREEZE DEVELOPS LATE THIS AFTERNOON OR BY EVENING. HIGH-RES MODEL WINDS DEPICT THIS MORE FULLY FOR KGYY AND KMDW...WITH A LITTLE LESS CONFIDENCE OF INLAND PUSH AT KORD...THOUGH A WEAKENING NORTH GRADIENT TYPICALLY SUPPORTS SUCH A LAKE BREEZE PUSH. IN ANY CASE PREVAILING WINDS SHOULD BE UNDER 10 KT...DECREASING TO LESS THAN 5 KT AND BECOMING WEST-SOUTHWEST AFTER SUNSET. RATZER //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM CONFIDENCE IN TIMING SHIFT TO NORTHEAST WINDS WITH LAKE BREEZE. * HIGH CONFIDENCE ALL OTHER FORECAST ELEMENTS. RATZER //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY THROUGH MONDAY...VFR. TUESDAY THROUGH THURSDAY...PERIODIC CHANCES FOR SHOWERS AND THUNDERSTORMS. BMD && .MARINE... 229 PM CDT WINDS WILL TURN NORTHWEST THIS EVENING AND THEN NORTH TONIGHT AND TOMORROW BEHIND A PASSING COLD FRONT. WARM WATER AND COOL AIR WILL ALLOW WINDS TO MIX DOWN EFFICIENTLY BUT THE GRADIENT IS NOT ESPECIALLY STRONG SO DO NOT ANTICIPATE EXCESSIVE WAVE GROWTH OR ANYTHING APPROACHING GALES EXCEPT FOR GUSTS NEAR STRONG STORMS THIS EVENING. TOMORROW AFTERNOON THE NORTH WINDS BEGIN TO BACK WEST AGAIN WHICH WILL ALLOW WAVE GROWTH TO BEGIN TAPERING OFF LATE IN THE DAY. ANOTHER WEAKER TROUGH OR FRONT CROSSES THE LAKE SATURDAY NIGHT...SO WINDS WILL BE VARIABLE FROM SOUTHWEST AHEAD OF IT TO NORTHWEST BEHIND IT...BUT HIGH PRESSURE AND QUIET WEATHER WILL BE THE MAIN STORY FOR THE OPEN WATERS THIS WEEKEND AFTER THIS EVENING AND TONIGHT. IN THE NEARSHORE THERE WILL BE A PERIOD LATE TONIGHT AND TOMORROW MORNING WHERE WAVES AND WINDS IN THE INDIANA NEARSHORE WILL LIKELY SUPPORT SMALL CRAFT ADVISORY CONDITIONS. LENNING && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 7 PM SATURDAY. LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 7 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 1208 AM CDT Sat Sep 6 2014 .UPDATE... ISSUED AT 825 PM CDT FRI SEP 5 2014 01z radar imagery shows leading edge of strong convection along a Paris to Shelbyville line moving eastward at around 40mph. Outflow boundary has pushed out ahead of the line, so other than gusty 40-45 mph winds along the outflow, severe weather threat is diminishing. The far eastern portion of Severe Thunderstorm Watch 496 still remains in effect, but will likely be canceled within the next hour or two. Behind the main line of storms, scattered showers and isolated thunderstorms extend as far west as the Mississippi River. Still a few stronger storms across central Missouri: however, these will weaken as well as they track across the St. Louis area into south-central Illinois later this evening. Have updated the forecast to reduce PoPs and go with only an isolated thunder mention across the W/NW KILX CWA. Further south and east of the main line, will stick with categorical thunder through midnight. && .SHORT TERM...(Tonight) ISSUED AT 259 PM CDT FRI SEP 5 2014 Cold front moving into the Illinois River Valley this afternoon with plenty of warm and moist air ahead of it. CAPEs ahead of the boundary are in excess of 4000 J/kg, but shear is minimal and the cu field has not yet responded to a lot of the heat of the day. Most of the activity associated with the boundary is actually well behind it, co-located with the best shear, but little in the way of CAPE. The activity that initiated along boundary just to the north is actually far more diurnally supported as it races out ahead of it. Convection will have plenty of PW to work with in the column should any storms develop, resulting in high precip and a threat for some precip loading/small microbursts and associated damaging winds. So far, remaining in the Slight Risk, but just outside a watch. Updating the pops to increase invof the boundary through sunset, then spreading out a bit more after sundown as the boundary moves through the region overnight. Temperatures starting to drop at GBG, so the temp curve tonight will vary a bit from diurnal and the lows will vary somewhat nw of the Illinois River Valley should any clear pockets develop. But llvl moisture hanging around quite a bit with the precip behind the front should prevent too much of a drop. && .LONG TERM...(Saturday through Friday) ISSUED AT 259 PM CDT FRI SEP 5 2014 The cold front will be clear of the forecast area by Saturday morning. This should take most of the precipitation risk with it. However, have maintained some morning showers south of I-70, as much of the precipitation with this front will be on the cool side of the front with the better upper forcing. Aside from the slight morning risk of rainfall in our southeast counties, the balance of the weekend into early next week will offer quiet and cooler than normal weather as Canadian high pressure builds into the area. From Tuesday through the end of the period the relatively zonal flow across the lower 48 will trend increasingly cyclonic as troffing develops. Model agreement of the disturbances in this developing trof is not that great as far as specifics. However, there is general agreement that Tuesday-Thursday will feature periodic showers/storms and remain cooler than normal. It also appears that a much cooler area of high pressure will help dry things out by Friday, with high temperatures by then possibly not making it out of the 60s for at least a day or two. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) ISSUED AT 1151 PM CDT FRI SEP 5 2014 Models have been a little slow in clearing precip from terminals this evening. HRRR is picking up on weak trough associated with low VFR clouds north of KPIA and KBMI. A few sites have dropped blo MVFR along trough with a slight shift to a less of a westerly component. A bit concerned that with precip this evening and dropping winds in middle of trough might produce some lowered vsbys. Will include a mention of tempo 5sm in KPIA and KBMI but later shifts will need to keep a close eye on trend. Cold advection will continue during the day tomorrow with gradual clearing from north to south. Skies should be SKC after sunset. Smith && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...BARNES SHORT TERM...HJS LONG TERM...BAK AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS PADUCAH KY
259 AM CDT Sat Sep 6 2014 .SHORT TERM...(Today through Monday night) Issued at 258 AM CDT SAT SEP 6 2014 With the first 12 to 18 hours of the short term forecast period, it becomes quite nebulous to depict the coverage of mainly post frontal precipitation across the WFO PAH forecast area. All the 3km HRRR guidance pinpoints the more significant storm scale convection prior to 15z, there is some discontinuity in coverage of precipitation in the medium scale numerical model guidance. Utilized a "Superblend" of numerical model guidance to modify and mitigate various model biases during the first 12-18 hours of Weather and PoP. The current shortwave moving across Southeast Kansas should bring the last gasp of convective activity across the WFO PAH forecast area later this morning/early this afternoon. Most of the convection early this afternoon should be waning over parts of West Kentucky. After this afternoon, dry conditions should dominate through most of Monday. .LONG TERM...(Tuesday through Friday) Issued at 258 AM CDT SAT SEP 6 2014 Model blend for the extended package. A blend of previous ECMWF deterministic runs coupled with 00z/12z GFS operational runs and the GEFS 00z run. The 18z GFS was discounted as was the 00z ECMWF mainly for Thursday night on. Backed off inherited PoPs for convection Tuesday through Tuesday night. Best moisture sets up north and west of the region. No surface focus and little support aloft to warrant much activity. Have no PoPs in Tuesday, and small chances Tuesday night mainly north of a Greenville, MO to Owensboro, KY line. Warm sector much of Wednesday as well. Strong surface low should reach either WI or the Great Lakes region with a trailing front to the SW, that will approach our area from the NW by the end of the day. Have best chance PoPs for convection up toward I-64 tapering off to 30s in west KY, parts of SEMO. Will probably be a sharper gradient. Our highest PoPs will be Wednesday night. Model cluster brings the front through Wednesday night with decent columnar moisture and mid level support in WSW flow around h5. Thursday the front should gradually push on through. Will have high chance PoPs across the south tapering off to slight chances up along I-64, especially morning, tapering off more in the afternoon. Went dry Thursday night. Could be some showers close to the AR/TN state lines, some of which could creep up north into our area. The 00z ECMWF is a significant outlier in spreading substantial moisture and QPF back across the region Thursday night. Given its prior 3 runs, and 4 runs of the GFS suggesting otherwise, threw this latest depiction out. Will monitor though, in case there`s a signal suggesting a slight northward adjustment will eventually be needed. Dry Friday through Friday night with strong high pressure continuing to build in from the NW. The cool down will be noticeable behind the front Thursday through Friday. We did not go quite as cool as raw model output. That means we raised previous highs just a bit. MOS tend to be climo bias that far out. But given the we should see some mid Sept. sun, a compromise seems best. && .AVIATION... Issued at 541 PM CDT FRI SEP 5 2014 Diurnal storms have really diminished in the last 30 minutes, and should be all but dissipated by issuance time. Will scatter some mid clouds, otherwise run with inherited MVFR cigs coming in with front late tonight. Tmrw shud see winds behind front go northerly as cigs slowly improve. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$ SHORT TERM...Smith LONG TERM...CN
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
350 AM EDT SAT SEP 6 2014 .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 350 AM EDT SAT SEP 6 2014 07Z SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE MOVING THROUGH EASTERN CANADA WITH A TRAILING COLD FRONT RUNNING SOUTHWEST THROUGH THE OHIO VALLEY AND INTO SOUTHERN MISSOURI. THE REMAINS OF A SQUALL LINE HAS SETTLED JUST SOUTH OF THE OHIO RIVER...OUT AHEAD OF THE COLD FRONT. A FEW LINGERING SHOWERS REMAIN WITH THIS AS IT CONTINUES TO FADE OUT WITH ITS APPROACH TO THE JKL CWA. ON SATELLITE...MID AND HIGH LEVEL CLOUDS COVER THE OHIO VALLEY NORTH AND WEST OF THIS OUTFLOW BOUNDARY. HOWEVER...THE CLEARER SKIES TO THE SOUTH HAS ALLOWED AREAS OF FOG TO DEVELOP THROUGH EAST KENTUCKY WITH LOCALLY DENSE PATCHES IN THE VALLEYS. HIGH DEWPOINTS IN THE UPPER 60S AND LOWER 70S ARE PROVIDING A FLOOR TO THE COOLING THIS NIGHT WITH JUST A SMALL RIDGE AND VALLEY SPLIT EVIDENT WITH READINGS VARYING FROM LOWER 70S IN THE THERMAL BELT TO THE UPPER 60S IN THE LOW SPOTS. WINDS REMAIN LIGHT TO CALM THROUGH THE AREA. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM AS HEIGHTS FALL OVER THE OHIO VALLEY IN RESPONSE TO A BROAD TROUGH MOVING THROUGH THE NORTHEAST PORTION OF THE CONTINENT. THE ENERGY STREAM ASSOCIATED WITH THIS MOVES QUICKLY INTO THE SOUTHERN OHIO VALLEY TODAY...BUT THEN LINGERS OVERHEAD THROUGH THE WEEKEND WITH A BIT OF A RESURGENCE LATER SUNDAY. GIVEN THE GOOD MODEL AGREEMENT... FOR WEATHER SPECIFICS HAVE FAVORED A BLEND OF THE HRRR AND NAM12 THROUGH THE FIRST HALF OF THE SHORT TERM FOLLOWED BY A MIX OF THE NAM AND LATEST ECMWF SOLUTIONS. SENSIBLE WEATHER WILL FEATURE AREAS OF FOG...LOCALLY DENSE...BURNING OFF EARLY THIS MORNING. THIS WILL BE FOLLOWED BY THE ARRIVAL OF SHOWERS AND THUNDERSTORMS BY MID AFTERNOON FROM NORTH TO SOUTH AS A COLD FRONT PRESSES SOUTH INTO THE AREA. PWS WITH THIS CONVECTION WILL BE MODERATELY HIGH WHILE STORM MOTION STARTS TO SPEED UP AS THE DAY WEARS ON. THIS SHOULD LIMIT THE RISK FOR FLASH FLOODING WHEN COMPARED TO THE PAST SEVERAL DAYS. HOWEVER...A LOCALIZED THREAT FOR HEAVY RAIN WILL REMAIN SHOULD TRAINING DEVELOP IN ANY PARTICULARLY LOCATIONS. THE THUNDER IS ANTICIPATED TO FADE FROM THE CONVECTION LATER TONIGHT AS THE FRONT SINKS SOUTH OF AREA LEAVING JUST LIGHT SHOWER TRAILING BEHIND. FOR SUNDAY...THE NEARBY FRONT MAY CAUSE A FEW SHOWERS TO POP UP OVER FAR SOUTHERN KENTUCKY AS THE BOUNDARY SLOWS IN RESPONSE TO A BUCKLE IN THE MID LEVEL FLOW AND A DEVELOPING WAVE AT THE SFC ALONG THE GEORGIA COAST. THE WARMTH AND STICKY HUMIDITY WILL LEAVE THE AREA AT LEAST FOR A COUPLE OF DAYS ONCE THE FRONT MOVES THROUGH MEANING THAT SUNDAY WILL BE A MUCH MORE COMFORTABLE DAY THAN TODAY AND PROVIDE A HINT OF THE FALL-LIKE WEATHER THAT COULD ARRIVE IN EARNEST LATER IN THE WEEK. FOR TEMPERATURES...DEWPOINTS...AND WINDS...USED THE CONSSHORT THROUGH THE FIRST 24 HOURS AND THEN THE SUPERBLEND THROUGH SUNDAY. DID MAKE SOME MINOR ADJUSTMENTS FOR TERRAIN DIFFERENCES WITH TEMPS TONIGHT. AS FOR POPS ENDED UP ON THE HIGH SIDE OF MOS GUIDANCE TODAY...COUNTING ON MOST OF THE AREA MEASURING AS THIS FRONT MOVES THROUGH GIVEN THE FAIRLY HIGH MOISTURE CONTENT IN PLACE. WAS SIMILAR TO THE GUIDANCE TONIGHT AND SUNDAY...LIMITING THE CHANCE POPS TO THE FAR SOUTHEAST. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 335 AM EDT SAT SEP 6 2014 THE MODELS CONTINUE TO BE IN GOOD AGREEMENT IN REGARDS TO A SIGNIFICANT PATTERN CHANGE FOR THE END OF NEXT WEEK...WITH A MAJOR COOL DOWN IN STORE. HOWEVER...THE MODELS DIFFER IN HOW THEY HANDLE THE EVOLUTION OF WEATHER SYSTEMS THAT WILL BRING SHOWERS AND STORMS TO EASTERN KENTUCKY DURING THE UPCOMING WORK WEEK. THE PERIOD WILL START OUT WARM AND DRY AS HIGH PRESSURE SUNDAY NIGHT THROUGH TUESDAY. THERE IS A POSSIBILITY OF SCATTERED SHOWERS AND STORMS FORMING BENEATH THE RIDGE ON MONDAY...AS MOISTURE OFF THE GULF OF MEXICO GETS DRAWN INTO THE AREA BY A WEAK AREA OF LOW PRESSURE THAT IS PROGGED TO PASS ACROSS THE TENNESSEE VALLEY. THE ECMWF WAS SLOWER AND WETTER THAN THE GFS FROM WEDNESDAY ONWARD. BOTH MODELS HAVE A COLD FRONT MOVING ACROSS THE OHIO AND TENNESSEE VALLEY REGIONS WEDNESDAY THROUGH FRIDAY...WITH SCATTERED SHOWERS AND STORMS FORMING IN THE VICINITY OF THE BOUNDARY. WITH UNCERTAINTY BETWEEN THE MODELS...DECIDED TO USE A BLEND OF THE ECMWF AND GFS MODELS...WITH A SLIGHT BIAS TOWARD TO NORMALLY MORE RELIABLE ECMWF SOLUTION. THE BEST CHANCES FOR RAIN WILL COME FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY EVENING DURING FRONTAL PASSAGE. TEMPERATURES THE FIRST FEW DAYS OF THE PERIOD LOOK TO BE AT OR SLIGHT BELOW NORMAL...DUE TO THE INFLUENCE OF NORTHERLY FLOW...CLOUD COVER...AND PRECIPITATION ASSOCIATED WITH AN AREA OF LOW PRESSURE THAT IS EXPECTED TO PASS THROUGH THE TENNESSEE VALLEY ON MONDAY. HIGHS ON MONDAY ARE EXPECTED TO TOP OUT AROUND 80...WITH READINGS MAXING OUT IN THE LOW TO MID 80S ON TUESDAY AND WEDNESDAY. THE BIG PATTERN CHANGE LOOKS LIKE IT WILL TAKE PLACE FROM THURSDAY ONWARD...AS A COOL CANADIAN AIR MASS SETTLES OVER THE REGION BEHIND A DEPARTING AND VERY POTENT COLD FRONT. HIGHS ON FRIDAY MIGHT ONLY TOP OUT IN THE LOW TO MID 70S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 205 AM EDT SAT SEP 6 2014 MAINLY VALLEY FOG IS ANTICIPATED DURING THE REMAINDER OF THE NIGHT...LIFTING AND DISSIPATING BY 13Z. ATTM...VIS IS EXPECTED TO FALL INTO THE MVFR RANGE AT THE TAF SITES...PENDING ON THE DEGREE OF CLEARING...BUT SOME IFR VIS COULD OCCUR. USED A BRIEF TEMPO GROUP FOR THIS UNCERTAINTY. MOST LIKELY...THE LOWER ELEVATION TAF SITES WILL EXPERIENCE JUMPS IN AND OUT OF IFR NEAR DAWN. A STRAY SHRA OR TSRA CANNOT BE RULED OUT AFTER 9Z IN THE FAR NW...BUT HIGHER CHANCES SHOULD HOLD OFF UNTIL AT LEAST 15Z ACROSS THE OFFICIAL TAF SITES. HIGH PROBABILITIES OF CONVECTION WILL OCCUR ALONG THE FRONTAL PASSAGE...SO WENT WITH PREVAILING TSRA AND WITH THE LOWER...MVFR... VIS AND CIGS STARTING AT 15Z AT THE FARTHEST NW SITE /KSYM/...AND 17Z AT THE SOUTHERN MOST SITE /KSME/ TO MATCH UP WITH ONGOING LIKELY TO CATEGORICAL POPS IN THE FORECAST. WINDS THROUGH THE BULK OF THE PERIOD WILL BE LIGHT AND VARIABLE BUT SWITCH TO THE NORTHWEST AT 5 TO 10 KTS BEHIND THE FRONT AS IT DROPS SOUTH DURING THE DAY...SATURDAY. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...AR AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
205 AM EDT SAT SEP 6 2014 .UPDATE... ISSUED AT 130 AM EDT SAT SEP 6 2014 CLEARING IN THE LATE EVENING OVER SOUTHEAST KENTUCKY LED TO A PERIOD OF RADIATIONAL COOLING FOR MUCH OF THE AREA. HOWEVER...WITH SUCH HIGH DEWPOINT AIR IN PLACE...TEMPERATURES DID NOT DROP TOO FAR...BUT AREAS OF FOG DID DEVELOP AND HAVE BECOME LOCALLY DENSE. UPDATED THE GRIDS TO REFLECT THIS AND ALSO SLOWED THE ARRIVAL OF CONVECTION UNTIL CLOSER TO DAWN OVER THE NORTHERN PARTS OF THE CWA. ADDITIONALLY... TWEAKED THE HOURLY T AND TD GRIDS FOR THE LATEST OBS...TRENDS...AND CONSSHORT DATA. THESE GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS AND A FRESHENED SET OF ZONES AND HWO WERE ISSUED. UPDATE ISSUED AT 1048 PM EDT FRI SEP 5 2014 LATEST TRACKING OF THE LINE OF STORMS TO OUR NW BRINGS THE LINE JUST TO THE NORTH OF THE CWA BETWEEN 7 AND 8Z THIS MORNING. SO FAR THE LATEST HRRR SEEMS TO BE FAIRLY WELL ON TRACK WITH THE ONGOING CONVECTION...AS DOES THE 00Z NAM12. BOTH MODELS POINT AT THE LINE EXPANDING AS IT NEARS THE OHIO RIVER VALLEY...WITH STORMS DEVELOPING OUT AHEAD OF THE MAIN LINE. THE HRRR IS A BIT QUICKER IN PULLING THESE SHOWERS AND THUNDERSTORMS INTO EASTERN KY AS COMPARED TO THE NAM12...AND SEEMS TO BE FOLLOWING THE CURRENT STORM MOTION BETTER THAN THE NAM12 AS WELL. THE ECMWF ALSO SUPPORTS THE HRRR SOLUTION...SO CHOSE TO RELY MORE HEAVILY ON THIS COMBINATION. IF BOTH THE HRRR AND ECMWF HOLD TRUE...INITIAL ISOLATED CONVECTION WILL SPREAD INTO THE NORTHERN COUNTIES OF THE CWA BETWEEN 9 AND 12Z...WITH THE MAIN LINE PASSING THROUGH SOMEWHERE CLOSER TO 18Z. THIS SEEMS TO BE FAIRLY ON TRACK WITH THE ONGOING FORECAST...SO HAVE MADE NO CHANGES FROM THE PREVIOUS UPDATE EARLIER THIS EVENING. THERE IS STILL A FAIRLY GOOD DEW POINT DEPRESSION ACROSS THE WESTERN AND NORTHERN PORTION OF THE CWA AT THE MOMENT. HOWEVER...A CONTINUED BREAK IN THE CLOUDS FOR THE NEXT FEW HOURS COULD BE ENOUGH TO PULL TEMPS DOWN AND ALLOW PATCHY FOG TO DEVELOP. GIVEN THE RAIN SHOWERS THIS EVENING OVER THE EASTERN CWA...DEW POINT DEPRESSIONS ARE MUCH LOWER HERE...SO EXPECT SOME PATCHY FOG TO PERHAPS BEGIN DEVELOPING A LITTLE SOONER IN THESE LOCATIONS. THIS MIGHT END UP BEING AN HOUR OR TWO SOONER THAN WHEN THE FOG IS MENTIONED IN THE GRIDS. OTHERWISE...THE ONLY OTHER UPDATE MADE WAS TO LOAD IN THE LATEST OBSERVATIONAL DATA FOR TEMPS...WINDS...AND DEW POINTS TO MAKE SURE CURRENT CONDITIONS WERE REFLECTED IN THE NEAR TERM FORECAST. THIS UPDATE RESULTED IN VERY LITTLE CHANGE FROM THE ONGOING FORECAST. UPDATE ISSUED AT 757 PM EDT FRI SEP 5 2014 GIVEN THE CURRENT RADAR TRENDS...AND LATEST HIRES MODEL DATA...DECIDED TO PUSH BACK THE ONSET OF SHOWERS AND THUNDERSTORMS BY SEVERAL HOURS. ORIGINAL FORECAST HAD SLIGHT CHANCES MOVING INTO THE FAR NW COUNTIES WITHIN THE NEXT 1 TO 2 HOURS. UNFORTUNATELY...THE LINE OF SHOWERS AND THUNDERSTORMS IS STILL OVER ILLINOIS AND NORTHERN INDIANA...AND IS NOT EXPECTED TO REACH KY FOR ANOTHER SEVERAL HOURS. EXPECT THAT WE WILL REMAIN DRY IN EASTERN KY THROUGH MUCH OF THE NIGHT...WITH SLIGHT CHANCES MOVING IN LATE TONIGHT IN THE NW...AND SLOWLY SPREADING SE NEAR DAWN. THIS ALSO SEEMED TO MATCH UP BETTER WITH SOME OF OUR SURROUNDING OFFICES. WOULD NOT BE SURPRISED THAT POPS MAY HAVE TO BE PUSHED BACK EVEN FURTHER LATER THIS EVENING/OVERNIGHT...UNLESS SOMETHING DEVELOPS OUT AHEAD OF THE MAIN LINE...BUT WILL WAIT TO SEE HOW THE CURRENT FORECAST PANS OUT FOR THE NEXT SEVERAL HOURS. STILL EXPECT PATCHY TO AREAS OF FOG TO DEVELOP AHEAD OF THE RAIN OVERNIGHT...SO LEFT FOG FORECAST UNTOUCHED FOR NOW. LOADED IN THE LATEST OBSERVATIONAL GUIDANCE FOR TEMPS...DEW POINTS...AND WINDS TO MAKE SURE THE NEAR TERM FORECAST WAS WELL ON TRACK WITH CURRENT CONDITIONS. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 415 PM EDT FRI SEP 5 2014 AS OF THE MID TO LATE AFTERNOON HOURS...AN UPPER LEVEL RIDGE OF HIGH PRESSURE REMAINS ACROSS THE SOUTHEASTERN CONUS WITH AN UPPER LEVEL TROUGH OVER THE NORTHERN AND CENTRAL PLAINS. ONE SHORTWAVE WAS WORKING ACROSS THE CENTRAL PLAINS...WHILE ANOTHER WAS WORKING EAST NEAR THE US/CANADIAN BORDER. THE SOUTHERN SHORTWAVE WILL WORK EAST AND INTO THE MID MS AND LOWER OH VALLEY REGION LATE TONIGHT AND INTO TOMORROW...THEN SLOWLY EAST ACROSS THE COMMONWEALTH THROUGH THE END OF THE PERIOD. THE NORTHERN SHORTWAVE IS PROJECTED TO WORK INTO THE NORTHEASTERN US DURING THAT TIME. THE PATTERN WILL RESULT IN TROUGH ACROSS THE NORTHEASTERN US AND OH VALLEY REGION BY THE END OF THE PERIOD. A COLD FRONT IN ADVANCE OF THIS TROUGH WILL WORK INTO THE OH VALLEY TONIGHT AND THEN ACROSS THE AREA THROUGH EARLY ON SATURDAY AFTERNOON. HIGH PRESSURE WILL BEGIN TO BUILD INTO THE ARE BEHIND THE FRONT ON SATURDAY EVENING AND SATURDAY NIGHT AND START TO USHER IN A COOLER AND LESS HUMID AIRMASS. CONVECTION HAS GENERALLY WANED OVER THE PAST COUPLE OF HOURS AS MUCH OF THE REGION HAS BEEN WORKED OVER. HOWEVER...ISOLATED CONVECTION LINGERS ACROSS THE BIG SANDY REGION AND THE VA BORDER COUNTIES. WE OPTED TO HOLD ONTO SOME SLIGHT CHANCE TO CHANCE POPS FOR THE FIRST HOUR OR TWO. A RELATIVE LULL IN THE CONVECTION CHANCES WILL OCCUR FROM THE EVENING INTO THE OVERNIGHT HOURS WITH THE LOSS OF DAYTIME HEATING AND IN ADVANCE OF THE SHORTWAVE TROUGH AND COLD FRONT. HOWEVER... SOME STRAY CONVECTION CANNOT BE COMPLETELY RULED OUT OVERNIGHT. ALSO...DEPENDING ON THE DEGREE OF CLEARING PATCHY FOG SHOULD ALSO DEVELOP...ESPECIALLY IN LOCATIONS THAT RECEIVED RAIN TODAY. THE AIRMASS REMAINS VERY MOIST AND WINDS ARE EXPECTED TO BE ON THE LIGHT SIDE. ON SATURDAY...THE CHANCES FOR CONVECTION WILL INCREASE ACROSS THE AREA AS THE COLD FRONT DROPS SOUTHEAST INTO THE REGION DURING THE MORNING. WITH SOME HEATING OF THE MOIST AIRMASS...SHOWERS AND THUNDERSTORMS NEAR THE BOUNDARY AND IN ADVANCE OF THE SHORTWAVE SHOULD BECOME RATHER NUMEROUS. CHANCES WILL BE THE HIGHEST IN THE NORTHWEST PART OF THE AREA FROM THE LATE MORNING INTO EARLY AFTERNOON AND THEN DURING THE AFTERNOON TO EARLY EVENING ACROSS THE REMAINDER OF THE REGION. THERE WILL BE PLENTY OF MOISTURE STILL IN PLACE FOR THE SHORTWAVE AND FRONT TO WORK WITH AND STORM MOTIONS WILL NOT BE ALL THAT HIGH. LOCALLY HEAVY RAIN WILL BE A THREAT FROM THESE. IF THERE IS AN AREA... POSSIBLY THE EASTERN OR SOUTHEASTERN PART OF THE AREA THAT GETS QUITE A BIT OF SUNSHINE IN THE MORNING...THEN A STRONG STORM OR TWO WITH STRONG WIND GUSTS WOULD ALSO BE POSSIBLE. THIS HAS BEEN HIGHLIGHTED IN THE HWO. CLOUDS AND THE THREAT FOR SHOWERS OR SOME LIGHT RAIN WILL LINGER INTO SATURDAY NIGHT...ESPECIALLY ACROSS THE SOUTHEAST. THUNDERSTORM CHANCES WILL ALSO DIMINISH BY LATE IN THE EVENING AS THE ATMOSPHERE STABILIZES. PLENTY OF LOW LEVEL MOISTURE AND LOW CLOUDS AND POSSIBLY STRATUS BUILD DOWN FOG WILL LINGER BEHIND THE BOUNDARY INTO SATURDAY NIGHT...AND CLOUD COVER SHOULD BE MOSTLY CLOUDY TO CLOUDY. LOW TEMPERATURES ON SATURDAY NIGHT WILL BE COLDER THAN RECENT NIGHTS...BUT RATHER CLOSE TO NORMAL. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 300 PM EDT FRI SEP 5 2014 THERE IS GOOD MODEL AGREEMENT ON THE OVERALL PATTERN CHANGE IN STORE FOR LATE NEXT WEEK...WITH MUCH COOLER AIR INVADING THE AREA AS COOL CANADIAN SURFACE HIGH PRESSURE INVADES THE PLAINS IN THE WAKE OF A COLD FRONT. HOWEVER...THE DAY TO DAY DETAILS AND TIMING OF EVENTS IS VERY UNCERTAIN...AND THERE CONTINUES TO BE LOW CONFIDENCE IN THE SPECIFICS OF THE FORECAST FOR NEXT WEEK. THE STANDARD MODEL BLEND LOAD HELPS TO TAKE INTO ACCOUNT THE VARIOUS MODEL DIFFERENCES...AND FOLLOWING THIS IDEA LEADS TO A CONTINUATION OF SHOWER AND THUNDERSTORM CHANCES FOR EVERY DAY NEXT WEEK. AFTER THE INITIAL COOL DOWN LATE THIS WEEKEND...TEMPERATURES WILL REBOUND AGAIN. THE BIG TEMPERATURE CHANGES BEING ADVERTISED WILL HAVE TO WAIT UNTIL THE END OF THIS FORECAST PERIOD AND BEYOND. IN ANY CASE A MORE FALL LIKE PATTERN WITH BELOW NORMAL TEMPERATURES IS IN STORE JUST BEYOND THE RANGE OF THIS FORECAST. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 205 AM EDT SAT SEP 6 2014 MAINLY VALLEY FOG IS ANTICIPATED DURING THE REMAINDER OF THE NIGHT...LIFTING AND DISSIPATING BY 13Z. ATTM...VIS IS EXPECTED TO FALL INTO THE MVFR RANGE AT THE TAF SITES...PENDING ON THE DEGREE OF CLEARING...BUT SOME IFR VIS COULD OCCUR. USED A BRIEF TEMPO GROUP FOR THIS UNCERTAINTY. MOST LIKELY...THE LOWER ELEVATION TAF SITES WILL EXPERIENCE JUMPS IN AND OUT OF IFR NEAR DAWN. A STRAY SHRA OR TSRA CANNOT BE RULED OUT AFTER 9Z IN THE FAR NW...BUT HIGHER CHANCES SHOULD HOLD OFF UNTIL AT LEAST 15Z ACROSS THE OFFICIAL TAF SITES. HIGH PROBABILITIES OF CONVECTION WILL OCCUR ALONG THE FRONTAL PASSAGE...SO WENT WITH PREVAILING TSRA AND WITH THE LOWER...MVFR... VIS AND CIGS STARTING AT 15Z AT THE FARTHEST NW SITE /KSYM/...AND 17Z AT THE SOUTHERN MOST SITE /KSME/ TO MATCH UP WITH ONGOING LIKELY TO CATEGORICAL POPS IN THE FORECAST. WINDS THROUGH THE BULK OF THE PERIOD WILL BE LIGHT AND VARIABLE BUT SWITCH TO THE NORTHWEST AT 5 TO 10 KTS BEHIND THE FRONT AS IT DROPS SOUTH DURING THE DAY...SATURDAY. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...JP LONG TERM...SBH AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
149 AM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL APPROACH THE EASTERN GREAT LAKES TONIGHT BRINGING A FEW SHOWERS OR THUNDERSTORMS TO UPSTATE NEW YORK MAINLY. THIS COLD FRONT WILL CROSS THE REGION SATURDAY WITH MORE WIDESPREAD SHOWER AND THUNDERSTORM ACTIVITY. ONCE THIS FRONT PASSES BY SATURDAY NIGHT...HIGH PRESSURE WITH COOLER AND LESS HUMID WEATHER WILL RETURN FOR SUNDAY AND MONDAY. && .NEAR TERM /THROUGH TODAY/... 950 PM UPDATE... A LINE OF INTENSE CONVECTION EXTENDS FROM LOWER ONTARIO BACK THROUGH ILLINOIS AT THIS HOUR. THE NORTHERN EDGE OF THE CONVECTION IS SHOWING SIGNS OF WEAKENING, WHILE THE MORE INTENSE PORTION OF THE LINE IS DIVING INTO THE UNSTABLE AIR OVER THE OHIO VALLEY (MLCAPES 2000-2500 J/KG). THIS OBSERVED TREND IS IN AGREEMENT WITH THE LATEST HRRR RUN, WHICH BRINGS A FEW THUNDERSTORMS INTO SOUTHWESTERN NY AROUND 6Z AND WEAKENS THEM CONSIDERABLY. MAKING A FEW TIMING ADJUSTMENTS TO THE POPS GRIDS FOR THE OVERNIGHT HOURS...OTHERWISE THE GRIDS APPEAR TO BE IN GOOD SHAPE. 4 PM DISC... RADARS SHOW SCATTERED SHOWERS AND SOME THUNDERSTORMS FIRING OVER THE CENTRAL MTNS OF PENNSYLVANIA WITH THE DIURNAL HEATING AND LOCALIZED MTN AND VALLEY CIRCULATIONS AS UPPER FORCING IS RATHER WEAK. SPC MESOANALYSIS SHOWS CAPES OF 1000 J/KG TO 1500 J/KG ACROSS MOST OF THE FINGER LAKES AND IN NORTHEAST PA WITH CAPES LESS THAN 1000 J/KG FARTHER NORTH TO THE UPPER MOHAWK VALLEY. WATER VAPOR IMAGERY CONTINUES TO SHOW AN ELONGATED PV MAXIMUM ON THE SOUTHERN EDGE OF THE WESTERLIES ACROSS THE OHIO VALLEY TO LOWER MISSISSIPPI VALLEY HEADING NORTHEAST INTO NE PA AND CENTRAL AND EASTERN NY STATE. ALL SYNOPTIC AND MESOSCALE MODELS BRING THIS SHEARING OUT WEAKENING FEATURE THRU C NY AND NE PA BY LATE AFTERNOON OR EARLY EVENING. AS THIS FEATURE PASSES BY I STILL CUD SEE AN ISLD SHOWER OR THUNDERSTORM OVER THE HIGHER TERRAIN OF THE POCONOS WHERE LOCALIZED UPSLOPE AND MTN-VLLY CIRCULATIONS CUD TRIGGER SOMETHING. REST OF AREA I DON/T SEE ANYTHING FORMING OF SIGNIFANCE THIS EVENING. SO I WILL MAINTAIN SLGHT CHC POPS FOR SHRA/TSRA UNTIL JUST AFTER 00Z WITH LOSS OF DAY/S HEATING IN THE POCONOS. NEXT FEATURE TO WATCH IN THE NEAR TERM WAS THE REMNANTS OF AN MCS TRACKING E-NE ACROSS LAKE HURON INTO SRN ONT. THE MEAN WINDS IN THE 850 MB TO 300 MB STEERING LAYER WERE FROM 250 DEGREES WITH THE INFLOW FOR THE STORMS FROM THE SOUTHWEST. THIS WILL KEEP THESE SHRA AND STORMS MOVING TO THE E AND MAINLY N OF C NY AND NE PA LATE AFTERNOON OR EARLY EVENING. BUT LATER TONIGHT...A STRONG UPPER LEVEL WAVE OVER JAMES BAY CANADA WITH ASSCTD STRONG SURFACE LOW WHICH TRIGGERED THIS MCS WILL PASS FARTHER EAST. THIS WILL PUSH A COLD FRONT SOUTHWARD. HENCE THE REMNANTS OF THIS MCS WILL BECOME REFOCUSED ALONG THIS COLD FRONT AND HEAD DOWN INTO NY STATE OVERNIGHT. THIS WILL OCCUR WHEN THE INSTABILITY IS AT ITS DIURNAL MINIMUM SO I EXPECT ACVTY WILL WANE AS IT DROPS S TO THE PA BRDR LATE TONIGHT AND EVENTUALLY FIZZLE. HAVE HIGHER POPS FOR SHRA/TSRA IN NC NY OVERNIGHT AND LOWER POPS FARTHER S WITH SLGHT CHC INTO NRN PA LATE TONIGHT. FOR SATURDAY...LOBE OF UPPER LEVEL PV FROM THE NRN PLAINS TO THE ROCKIES WILL RAPIDLY WORK EAST TONIGHT AND REACH THE GREAT LAKES REGION TO CENTRAL PLAINS BY 12Z SATURDAY AND THEN INTO THE ERN LAKES BY 00Z SUNDAY. THIS IS A POTENT FEATURE AND WILL LEAD TO SIGNIFICANT HEIGHT FALLS...LIFTG AND COOLING ALOFT AND BE THE IMPETUS FOR PUSHING A STRG COLD FRONT THRU NY AND PA SAT. AHEAD OF THE COLD FRONT RICH BOUNDARY LAYER MOISTURE EXISTED WITH DEWPOINTS APPRCHING OR ABV 70F. CAPES EASILY CUD APPROACH 1500 J/KG AHEAD OF FRONT BETWEEN 18Z AND 00Z. WITH THE UPPER LEVEL RDG HOLDING OFFSHORE...THE HEIGHT GRADIENT INCREASES ALSO AS THIS UPPER FEATURE PRESSES EASTWARD WHICH INCREASES THE MID TO HIGH LEVEL WINDS AND EVEN THE LL WINDS. HENCE WIND SHEARS WILL BE FAIRLY IMPRESSIVE. THE 0-1 KM SHEAR WAS PROJECTED TO BE 15 TO 20 KNOTS...THE 0-6 KM SHEAR PRIOR TO CONVECTION FIRING WAS PROGGED TO BE CLOSE TO 40 KNOTS OR SLIGHTLY MORE. HENCE BELIEVE POTENTIAL EXISTS FOR SEVERE STORMS IN OUR FORECAST AREA MAINLY SAT PM. FRONTAL POSITIONING WILL BE THE KEY TO WHERE THE RISK AREA IS FOR SEVERE STORMS IN OUR FORECAST AREA. THE GFS...NAM...EURO SEEM TO AGREE THAT BY 18Z THE INSTABILITY GRADIENT WILL RUN FROM ABT COOPERSTOWN TO UCA SW TO BRADFORD CO INCLUDING BGM AND ELM IN OUR FORECAST AREA. SO LOCATIONS S AND E OF HERE WILL HAVE THE HIGHEST RISK FOR SEVERE. THE CMC IS FARTHER S AND WUD INDICATE ONLY THE POCONOS TO SULLIVAN COUNTY SEE POTENTIAL FOR INSTABILITY AND SEVERE WEATHER IN THE NWS BGM FORECAST AREA. OUR LOCAL SEVERE WEATHER CHECKLIST SUGGESTS POTENTIAL FOR BROKEN LINES AND SMALL BOW ECHOE STRUCTURES WITH WIND DAMAGE THE PRIMARY THREAT. PWATS ALSO WERE RUNNING ARND 1.8 INCHES SO HEAVY RAIN IS ALSO WORTH HIGHLIGHTING. NORTH OF THIS BNDRY...I SEE MAINLY SHRA IN THE MORNING WITH ISLD THUNDER WITH THE MAIN ACVTY REMAINING TO THE S. WILL CONTINUE TO HIGHLIGHT IN THE HWO. && .SHORT TERM /TONIGHT THROUGH MONDAY/... FOR SATURDAY NIGHT...FRONT PASSES E AND HIGH PRESSURE RAPIDLY SPREADS ACROSS NY AND PA WITH LIGHT WINDS AND CLEARING SKIES AS PER SYNOPTIC MODELS. WITH FAIRLY WIDESPREAD RAINFALL SATURDAY I SEE PLENTY OF VALLEY FOG FORMING BY SUN AM AND HAVE IN GRIDS. FOR SUNDAY AND SUNDAY NIGHT...HIGH PRESSURE REMAINS OVER THE REGION WITH FAIR AND PLEASANT DAYTIME WEATHER AND A CHILLY NIGHT. AGAIN I SEE PLENTY OF VALLEY FOG BY MONDAY AM WITH CLEAR SKIES LIGHT WINDS AND MINS WELL DOWN INTO THE 40S MANY AREAS. FOR MONDAY...HIGH PRESSURE WORKS E AND A SRLY RETURN FLOW BEGINS WITH SOME MODERATING BEGINNING. I DON/T EXPECT ANY PRECIP. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... 130 PM UPDATE... EXPECT SFC HIPRES TO BE BUILDING INTO THE CANADIAN MARITIMES AT THE START OF THE LONG TERM PD. A WEAK SFC LOW WL LKLY DVLP ALONG THE ERN SEABOARD TUE MRNG AS WV RIDES UP ALONG THE COAST BUT WITH 1030MB HIGH CONTROLLING AREA WX NOT EXPECTING MUCH IN THE WAY OF PCPN TO MV INTO CWA UNTIL MORE TWD TUE EVNG AND EVEN AT THAT EXPECT IT TO BE A LONG SHOT. CHC FOR SHOWERS/TSTMS CAN BE EXPECTED BEGINNING WED MRNG WITH ANOTHER TROF (DEEPER ON EC VS GFS) WORKING ITS WAY INTO THE NORTHEAST U.S. MODELS DIFFER ON POP CHANCES AFTR WED NGT WITH 12Z GFS MUCH QUICKER MVG LOPRES THRU THAN 00Z EC. MAIN REASON IS THAT 00Z EC IS MUCH MORE AMPLIFIED WITH SYSTEM AND DEEPER WITH SFC LOW. THIS IS MORE IN LINE WITH GFS ENSEMBLE MEAN AND MAJORITY OF THE ENSEMBLE MEMBERS. EXPECT TEMPS THRU THE PD TO BE NEAR. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... REMNANTS OF MCS WILL SLIDE THROUGH AT LEAST KELM-KITH EARLY THIS MORNING...AND POSSIBLY KBGM. CONVECTIVE TRENDS HAVE BEEN SURGING WITHIN THE LAST HOUR PRIOR TO THIS DISCUSSION...BUT ALL CONVECTION ALLOWING MODELS SUGGEST A RAPID DISSIPATION OF ACTIVITY BY 09Z. HAVE GONE A LITTLE HEAVIER THAN THE MODEL GUIDANCE WITH CARRYING THE STRATIFORM RAIN INTO THE AREA...BUT THE THUNDER THREAT MAY ACTUALLY BE WHAT DIMINISHES. AREAS OF MVFR CIGS/VSBYS SEEM FAIRLY PLAUSIBLE...WHILE THE GUIDANCE OFFERING UP STRONG IFR SIGNALS DOES NOT. THEN...DURING A BRIEF LULL IN RAIN ACTIVITY...THE SURFACE FRONTAL BOUNDARY QUIETLY SLIPS THROUGH THE NORTHERN AND WESTERN HALF OF THE REGION LATER THIS MORNING WITH MAINLY SHOWERS AND SCATTERED MVFR RESTRICTIONS EXPECTED INTO THE MID AFTERNOON AS A POTENT UPPER DISTURBANCE PUSHES THINGS ALONG TO THE EAST. BEST CHANCE FOR CONVECTIVE THUNDER THREAT APPEARS TO BE AT KAVP LATER THIS AFTERNOON...AND KBGM MAY BE JUST ON THE NORTHERN FRINGE OF THE NEW DEVELOPMENT. DRIER AIR...AND A GRADUAL TREND TO VFR NO CIG DEVELOPS TOWARD THE END OF THIS FORECAST. THEN...GIVEN THE RAIN...PROBLEMATIC MVFR/IFR VSBYS COULD DEVELOP BEYOND THE VALID TIME OF THIS FORECAST EARLY SUNDAY MORNING. WILL ADDRESS THAT LATER. OUTLOOK... LATE SAT NIGHT...MVFR/IFR VSBYS/CIGS POSSIBLE. SUN-WED...MOSTLY VFR WITH POTENTIAL FOR IFR FOG RESTRICTIONS EACH MORNING, ESPECIALLY ELM. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN/DJP NEAR TERM...DJN SHORT TERM...DJN LONG TERM...PVN AVIATION...JAB
AREA FORECAST DISCUSSION
NWS HOUSTON/GALVESTON TX
1143 PM CDT FRI SEP 5 2014 .DISCUSSION... SEE 06Z AVIATION DISCUSSION. && .AVIATION... 00Z MODELS HAVE COME IN A BIT MORE MOIST THAN THE 18Z RUN. PWATS ARE PROGGED TO INCREASE SAT MORNING TO BETWEEN 1.90 AND 2.10 INCHES. A STRONG UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE REGION ON SAT AFTN AS WELL. CONVECTIVE TEMPS ARE NEAR 86 ALONG THE COAST TO 89 WELL INLAND. BOTH THE RAP AND HRRR SHOW CONVECTION DEVELOPING AROUND 16Z AND EXPANDING IN COVERAGE THROUGH THE EARLY AFTN. WILL CARRY VCTS FOR ALL TAF SITES BEGINNING AT 12Z NEAR THE COAST...16Z CENTRAL ZONES AND AROUND 19-20Z WELL INLAND. A WEAK BOUNDARY WILL APPROACH THE NORTHERN TAF SITES AROUND 06Z. 43 && .PREV DISCUSSION... /ISSUED 940 PM CDT FRI SEP 5 2014/ UPDATE... SEE DISCUSSION FOR EVENING UPDATE. DISCUSSION... SHOWERS AND THUNDERSTORMS HAVE COME TO AN END THIS EVENING. FORECAST SOUNDINGS FOR TOMORROW DON`T LOOK TO FAVORABLE FOR RAIN CHANCES WITH AVERAGE MOISTURE AND LOW K INDEX VALUES. UPPER LEVEL WINDS ALSO SHOW A LIGHT CONFLUENT PATTERN. AT 500MB THOUGH A POCKET OF VORTICITY IS FORECASTED TO BREAK AND WASH OVER THE COAST TOMORROW. FORECAST SOUNDINGS ALSO SHOW PLENTY OF INSTABILITY. HIGH RES TEXAS TECH WRF AND RAP SHOWS COVERAGE INCREASING TOMORROW AFTERNOON. THINK CHANCE POPS ARE THE WAY TO GO GIVEN THE INSTABILITY IN FORECAST SOUNDINGS. CURRENT FORECAST HAS THIS COVERED. NO UPDATE REQUIRED AT THIS TIME. 23 PREV DISCUSSION... /ISSUED 630 PM CDT FRI SEP 5 2014/ DISCUSSION... A FAIRLY DEEP UPPER LEVEL RIDGE WILL REMAIN OVER SE TX FOR MOST OF THE UPCOMING FORECAST PERIOD. A WEAKNESS IN THE RIDGE WILL MOVE OVER SE TX FROM THE EAST AS A COLD FRONT DROPS SOUTHWARD TOWARD THE FORECAST AREA. THIS WILL HELP KEEP SCATTERED THUNDERSTORM CHANCES IN PLACE THROUGH SUNDAY. THE RIDGE WILL BUILD AGAIN OVERHEAD THROUGH MID WEEK. TOWARD THE END OF THE WORK WEEK...A STRONGER COLD FRONT MAY APPROACH THE AREA FROM THE NORTH. MODEL FORECAST SOUNDINGS SHOW A SIMILAR SETUP FOR WHAT OCCURRED TODAY FOR SATURDAY. WITH NO CAP...PW/S NEAR 2 INCHES...AND FORECAST CAPE VALUES OF 3000 TO 3500...EXPECT THAT ISOLATED STRONG THUNDERSTORMS WILL BE AGAIN POSSIBLE. THE MAIN THREAT WILL BE STRONG GUSTY WINDS IN EXCESS OF 40 MPH...FREQUENT CLOUD-TO-GROUND LIGHTNING...AND LOCALLY HEAVY RAINFALL. THE HIGH RESOLUTION ARW AND NMM BOTH FORECAST THE COLD FRONT TO APPROACH THE NORTHERN COUNTIES DURING THE EVENING. THIS MAY HELP TO KEEP AT LEAST ISOLATED STORMS ACROSS THE FORECAST AREA SATURDAY NIGHT. THE GLOBAL MODELS DO NOT PUSH THE FRONT ALL THE WAY THROUGH THE AREA ON SUNDAY AND THEN MOVE IT BACK NORTH LATE SUNDAY INTO MONDAY. THIS SHOULD KEEP SCATTERED STORMS ON SUNDAY AND ISOLATED CHANCES ON MONDAY. FOR TUESDAY AND WEDNESDAY THE RIDGE WILL LIKELY KEEP RAIN CHANCES TO A MINIMUM. THE GFS AND ECMWF THEN DIFFER FOR THURSDAY...WITH THE GFS FASTER WITH THE APPROACH OF THE NEXT COLD FRONT THURSDAY EVENING. WOULD LIKE TO SEE A BIT BETTER MODEL CONSISTENCY...PLUS FELT THAT THE SLOWER ECMWF MAY BE THE BETTER MODEL GIVEN THE UPPER LEVEL PATTERN. BOTH MODELS HAVE SWITCHED FROM A NORTHWESTERLY FLOW TO KEEP THE CENTER OF THE RIDGE A BIT FURTHER TO THE NORTH. 40 MARINE... LIGHT ONSHORE WINDS WILL PERSIST THRU THE WEEKEND. PRESSURE GRADIENT WILL BE WEAK ENOUGH TOWARD THE END OF THE WEEKEND AND EARLY NEXT WEEK THAT WE`LL PROBABLY SEE A DISTINCT LANDBREEZE/ SEABREEZE CIRCULATION (BRIEF OFFSHORE FLOW LATE AT NIGHT & EARLY MORNING BECOMING ONSHORE DURING THE DAY). OTHERWISE...SCATTERED SHOWERS/TSTMS CAN BE EXPECTED EACH DAY. MOST FAVORED TIMES BETWEEN 2- 10AM. 47 && .PRELIMINARY POINT TEMPS/POPS... COLLEGE STATION (CLL) 74 95 74 94 74 / 30 40 30 30 20 HOUSTON (IAH) 75 92 75 93 74 / 30 40 30 30 20 GALVESTON (GLS) 82 90 80 89 78 / 30 30 20 30 20 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ DISCUSSION...23 AVIATION/MARINE...43
AREA FORECAST DISCUSSION...CORRECTED
NWS BLACKSBURG VA
342 AM EDT SAT SEP 6 2014 .SYNOPSIS... A STRONG COLD FRONT WILL PUSH THROUGH OUR AREA TODAY AND THIS EVENING...HELPING TO IGNITE SCATTERED TO NUMEROUS SHOWERS AND STORMS. THIS FRONT WILL STALL SOUTH OF THE REGION THROUGH EARLY NEXT WEEK...KEEPING CLOUDS ALONG WITH THE THREAT FOR SHOWERS...BUT COOLER TEMPERATURES. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 AM EDT SATURDAY... A MOIST AIRMASS CONTINUES TO RESIDE OVER THE FORECAST AREA EARLY SATURDAY MORNING...WITH THE 00Z SOUNDINGS FROM RNK AND GSO YIELDING PWAT VALUES 150-160% OF NORMAL. ANOTHER MORNING OF PATCHY DENSE FOG AND LOW CLOUDS CAN BE EXPECTED AND WILL COVER ANY PATCHY DENSE FOG ISSUES WITH A SPECIAL WEATHER STATEMENT. THE FOCUS TODAY WILL BE ON A COLD FRONT LOCATED FROM NORTHWEST OHIO TO CENTRAL INDIANA INTO WESTERN KENTUCKY AT 06Z. SREF/GFS/NAM/ECMWF ALL INITIALIZED THE LOCATION OF THIS BOUNDARY WELL...AND AGREE THIS FEATURE ENTERS THE WESTERN PORTION OF OUR FORECAST AREA AROUND 18Z...AND TRIES TO EXIT THE FAR SOUTHEAST PORTION OF OUR FORECAST AREA BETWEEN 00Z-06Z TONIGHT. AS THE BOUNDARY BECOMES PARALLEL TO THE UPPER FLOW...ITS SOUTHWARD PROGRESSION WILL SLOW. IN ADVANCE OF THIS FRONT...A WESTERLY COMPONENT TO THE LOW LEVEL WINDS SHOULD ALLOW FOR SOME CLEARING TODAY AS WELL AS DESTABLIZATION. FORECAST 0-6KM SHEAR VALUES INCREASE TO 20-25KTS AFTER 21Z...SO SOME STORM ORGANIZATION IS EXPECTED. IN ADDITION TO THE POTENTIAL FOR LOCALLY HEAVY RAINS WITH PWAT VALUES STILL 1-2 STANDARD DEVIATIONS ABOVE NORMAL TODAY...A SMALL DAMAGING WIND THREAT EXISTS...WHICH WILL BE NOTED IN THE HAZARDOUS WEATHER OUTLOOK. COVERAGE OF SHOWERS AND STORMS SHOULD ONLY BE WIDELY SCATTERED IN ADVANCE OF THE FRONT WITH A WEAK SOUTHWEST/WEST LOW LEVEL WIND...AND GFS MAY BE OVERDONE WITH PRECIP COVERAGE AT 18Z. PLACED HIGHEST POPS LATER IN THE DAY WHEN THE BETTER LOW LEVEL CONVERGENCE ARRIVES WITH THE FRONT. THE GFS MOS IS ONCE AGAIN SIGNIFICANTLY WARMER THAN MOST GUIDANCE FOR HIGHS TODAY. WITH SOME CLEARING AND WEAK DOWNSLOPE WIND...HIGHS TODAY SHOULD BE WARMER THAN VALUES ON FRIDAY. HOWEVER...WITH INCREASING CLOUDS TODAY...USED A BLEND OF THE NAM/GFS MOS. BY 12Z SUNDAY...THE SFC FRONT IS FORECAST TO BE IN CENTRAL NC...BUT PRECIPITATION IN THE SOUTHEAST PORTION OF THE FORECAST AREA WILL LIKELY BE SLOW TO END WITH THE SLOW MOVEMENT OF THE FRONT...ALONG WITH GOOD UPPER LEVEL DIVERGENCE ASSOCIATED WITH A RR QUAD OF AN UPPER LEVEL JET MOVING THROUGH THE EASTERN GREAT LAKES AND NEW ENGLAND. LOW CLOUDS AND AND LIGHT PRECIP WELL TO THE NORTH OF THE BOUNDARY WILL BE POSSIBLE AS WEDGE BEGINS TO BUILD. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... AS OF 330 AM EDT SATURDAY... OVERALL LOOKS LIKE A DAMP/WEDGE PATTERN FOR US THIS PERIOD. MODELS ARE DIFFERING ON STRENGTH/POSITION OF A SFC LOW OVER THE SE COAST SUN-TUE...BUT PER TRENDS/WPC GUIDANCE THE 00Z ECMWF/GFS SEEM IN THE BALL PARK ON THIS SYSTEM. DIFFERENCES BETWEEN THESE MODELS LIES IN THE QPF FIELD. THE GFS SEEMS INLAND TOO MUCH WITH QPF MONDAY...THINKING A LOT OF DEEP MOISTURE WILL RESIDE ACROSS THE COASTLINE WITH CONVECTION AND HENCE ROB SOME INFLOW INTO OUR NECK OF THE WOODS. FOR SUNDAY...THE SFC LOW WILL BE OVER GEORGIA/SOUTH CAROLINA WHILE SFC HIGH STRETCHES FROM IA/MO ENE INTO WRN PA/NY. THE FLOW WILL TURN MORE NE-E WITH INCREASING MOISTURE. SFC FRONT WILL BE SOUTHEAST OF US ACROSS ERN NC...BUT SW FLOW ALOFT COMBINED WITH EASTERLY FLOW WILL KEEP MOISTURE INFLOW INTO OUR REGION WITH HIGHER THREAT ALONG THE SRN BLUE RIDGE SUNDAY AFTERNOON. THE SFC HIGH MOVES QUICKLY NE AND SETS UP OVER NEW ENGLAND/SRN QUEBEC SUNDAY NIGHT WITH FRONTAL SYSTEM REMAINING ALONG THE COAST...WITH INVERTED TROUGH IN ERN TN. FAVORING A BETTER THREAT OF SHOWERS EAST OF THE BLUE RIDGE SUNDAY NIGHT OVER INTO MONDAY NIGHT...AS THE LOW SLIDES SLOWLY NWD ACROSS ERN NC THEN OFF THE VA COAST. THE MODELS START TO SHOW DRIER AIR WORKING IN FROM THE WEST TUESDAY MORNING...WITH DEEP MOISTURE SHIFTING OUT TO SEA. TUESDAY WILL BE A DRIER DAY BUT MODELS SHOWING ANOTHER SYSTEM MOVING INTO THE SRN PLAINS WITH UPPER SHORTWAVE SHIFTING ALONG THE NRN EDGE OF THE RIDGE THAT REMAINS OVER THE GULF COAST INTO OUR REGION. ATTM...NOT TOO IMPRESSED WITH PRECIP CHANCES TUESDAY WITH MAINLY AFTERNOON/EVENING SHOWERS AND STORMS SCATTERED ACROSS THE BLUE RIDGE AND ADJACENT COUNTIES WEST INTO THE WV MOUNTAINS. TEMPS THIS PERIOD REMAIN TRICKY BUT WILL MOS SEEMS TO HAVE A DECENT HANDLE ON HIGHS. SUNDAY WILL BE TRANSITION DAY...BUT WILL SEE HIGHS MAINLY IN THE 70S BEHIND THE FRONT WITH NE WINDS. IF PRECIP IS MORE WIDESPREAD HIGHS MONDAY MAY NOT GET OUT OF THE 60S IN THE EAST. FOR NOW I AM LEANING TOWARD THE MAV WHICH HAS HIGHS FROM THE LOWER TO MID 70S IN THE WEST TO UPPER 70S/LOWER 80S ACROSS THE FAR SW CWA...WITH SOME 60S IN BLUE RIDGE HIGHER TERRAIN AS WELL AS THE ALLEGHANYS. TUESDAY WILL BE WARMER WITH FLOW WEAKENING AND TURNING MORE NNW. HIGHS WILL RANGE FROM THE MID TO UPPER 70S WEST TO LOWER 80S SOUTHEAST. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... AS OF 400 PM EDT FRIDAY... ON WEDNESDAY...A COLD FRONT SWEEPS ACROSS THE NORTHERN PLAINS WITH A SURFACE WAVE TRACKING NORTHEAST TOWARDS THE GREAT LAKES. AS THIS WAVE MOVES INTO ZONAL FLOW...IT WILL THEN TRACK OVER THE OHIO VALLEY WEDNESDAY AFTERNOON/EVENING. THIS WAVE WILL KEEP BULK OF THE STRONGER CONVECTION NORTH IN THE OHIO VALLEY. AS THIS WAVE ENTERS THE OHIO VALLEY...THE WEDGE THAT WAS OVER THE MID ATLANTIC REGION MONDAY AND TUESDAY WILL BEGIN TO ERODE. IF THIS WEDGE REMAINS DRY WHILE IN THE AREA...IT SHOULD HAVE NO PROBLEMS ERODING WEDNESDAY. IF THIS WEDGE HAS RAIN TO ENHANCE IT...IT MAY NOT CLEAR THE AREA UNTIL LATE WEDNESDAY NIGHT. MODELS ARE PUSHING THIS COLD FRONT ACROSS THE REGION ON THURSDAY. AS IN THE CASE WITH THE FRONT EARLY IN THE WEEK...DOES THIS FRONT CLEAR THE FORECAST AREA OR DOES IT STALL IN THE VICINITY. SINCE THIS FRONT IS TRYING TO TRACK SOUTH IN ZONAL FLOW...THE POSSIBILITIES OF A SLOWER ARRIVAL (FRIDAY AND/OR SATURDAY) OR HAVING THE FRONT STALL OVER THE REGION IS HIGH. SINCE THIS IS POSSIBLE...WILL KEEP CHANCE POPS IN FOR FRIDAY. AREAS THAT HANG ON TO THE WEDGE WEDNESDAY WILL HAVE COOLER THAN NORMAL TEMPERATURES. IF OUTSIDE THE WEDGE...AT OR ABOVE NORMAL TEMPERATURES ARE LIKELY. THE WARMEST DAY OF THE WEEK SHOULD BE THURSDAY...ESPECIALLY IF THE FRONT IS SLOW TO TRACK EAST. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... AS OF 120 AM EDT SATURDAY... UNDER A MOIST AIRMASS...AREAS OF LOCALLY DENSE FOG AND LIFR TO MVFR CIGS AND VISIBILITIES WILL REDEVELOP EARLY THIS MORNING...ESPECIALLY IN THE MOUNTAIN VALLEYS AND LOCATIONS THAT RECEIVED RAINFALL ON FRIDAY. DAYTIME HEATING WILL ALLOW FOG TO BURN OFF QUICKLY AFTER 9 AM SATURDAY...POSSIBLY TAKING LONGER IN THE MOUNTAIN VALLEYS. A COLD FRONT WILL MOVE THROUGH OUR AREA SATURDAY AFTERNOON...BRINGING SHOWERS AND STORMS TO MUCH OF THE REGION. THE COVERAGE OF THE PRECIPITATION WILL BE MORE WIDESPREAD THAN WHAT HAS BEEN SEEN OVER THE PAST FEW DAYS. LOCALLY HEAVY RAIN AND GUSTY WINDS WILL BE POSSIBLE UNDER THE STRONGER STORMS WITH LOCAL IFR CONDITIONS UNDER THE STRONGER STORMS. THIS FRONT WILL ADVANCE SOUTH OF OUR AREA BY SATURDAY EVENING...AND A LOW LEVEL NORTH/NORTHEAST WIND DEVELOPING LATE SATURDAY NIGHT WILL USHER IN LIFR TO IFR CLOUDS...ESPECIALLY AT THE MOUNTAIN TAF SITES. THE FRONT WILL BE STALLED JUST SOUTH OF THE AREA SUNDAY AND MONDAY...MAINTAINING CLOUD COVER AS WELL AS A THREAT FOR SHOWERS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PH NEAR TERM...PH SHORT TERM...WP LONG TERM...RCS AVIATION...PH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1128 PM CDT FRI SEP 5 2014 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 353 PM CDT FRI SEP 5 2014 AT 3 PM...A STRONG CANADIAN COLD FRONT EXTENDED FROM NEW BERLIN WISCONSIN SOUTHWEST TO WEATHERFORD OKLAHOMA /KOJA/. TEMPERATURE AHEAD OF THIS COLD FRONT RANGED FROM THE MID 80S TO MID 90S WITH DEW POINTS IN THE 70S. MEANWHILE BEHIND THIS COLD FRONT... TEMPERATURES WERE IN THE 60S AND 70S WITH DEW POINTS IN THE 50S. A BAND OF 900 TO 700 MB FRONTOGENESIS IS GENERATING A BAND OF SHOWERS ACROSS PARTS OF NORTHEAST IOWA AND SOUTHWEST WISCONSIN. IN ADDITION WITH THE RAP SHOWING MOST UNSTABLE CAPES UP TO 500 J/KG AND SOME SLANTWISE CONVECTION...KEPT ISOLATED THUNDERSTORMS IN THE FORECAST. WITH FAIRLY LIMITED MOST UNSTABLE CAPES AND UNFAVORABLE 0-3 KM OR 0-6 KM SHEAR...NOT ANTICIPATING ANY OF THESE THUNDERSTORMS TO BECOME SEVERE. MEANWHILE FURTHER NORTHWEST ACROSS SOUTHEAST MINNESOTA...700 TO 500 MB FRONTOGENESIS IS PRODUCING ANOTHER BAND OF SHOWERS. FOR EARLY THIS EVENING...THE RAP SHOWS THAT THE 2 BANDS OF FRONTOGENESIS WILL MOVE QUICKLY SOUTHEAST OF THE FORECAST AREA BY 06.03Z. AS THIS OCCURS...THE SHOWERS AND ISOLATED THUNDERSTORMS WILL MOVE OUT OF THE AREA. AS A RESULT...WENT WITH A QUICK LOWERING OF THE PRECIPITATION PROBABILITIES FROM WEST TO EAST ACROSS SOUTHEAST MINNESOTA...NORTHEAST IOWA...AND IN WESTERN WISCONSIN SOUTH OF INTERSTATE 90 BETWEEN 05.23Z AND 06.03Z. IN ADDITION TO THIS...THE CLOUDS SHOULD BE QUICKLY ON THE DECREASE. FOR LATE TONIGHT...THE BUFKIT SOUNDINGS SHOW A SHALLOW LAYER /A COUPLE OF HUNDRED FEET/ OF LIGHT WINDS WITH 10 TO 20 KNOTS ABOVE 300 FEET. THESE WINDS SHOULD MAKE IT UNFAVORABLE FOR THE DEVELOPMENT OF FOG TONIGHT. ON SATURDAY...BUFKIT SOUNDINGS SHOW VERY STEEP 900 TO 750 MB LAPSE RATES /9-10 C/KM/ ACROSS THE AREA. THIS WILL ALLOW THE WIND GUSTS TO CLIMB INTO THE 10 TO 20 KNOT RANGE. IN ADDITION...THIS WILL ALLOW DRIER AIR FROM ALOFT TO MIX TO THE SURFACE. AS A RESULT... LOWERED THE DEW POINTS INTO THE 45 TO 50 DEGREE RANGE. THIS STILL MAY BE ON THE HIGH SIDE...BUT THE TREND IS IN THE RIGHT DIRECTION. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 353 PM CDT FRI SEP 5 2014 FROM LATE SATURDAY NIGHT INTO SUNDAY MORNING...THE LAYER OF LIGHT WINDS ONCE AGAIN LOOK VERY SHALLOW. IN ADDITION...THE DEW POINTS ARE SHOWING A SLOW RECOVERY. AS A RESULT...UNCERTAIN OF WHETHER ANY VALLEY FOG WILL OCCUR OR NOT. SO JUST WENT WITH PATCHY FOG IN THE RIVER VALLEY AND THE CRANBERRY BOGS OF CENTRAL WISCONSIN. ON SUNDAY AFTERNOON...BUFKIT SOUNDINGS SHOW VERY STEEP 900 TO 750 MB LAPSE RATES /8-10 C/KM/ ACROSS THE AREA. THIS WILL ALLOW DRIER AIR FROM ALOFT TO MIX TO THE SURFACE. AS A RESULT...LOWERED THE DEW POINTS INTO THE 45 TO 50 DEGREE RANGE. FROM MONDAY AFTERNOON THROUGH WEDNESDAY...THE MODELS CONTINUE TO SHOW THAT A SERIES OF SHORT WAVE TROUGHS WILL MOVE THROUGH THE REGION. DUE TO RUN TO RUN MODEL INCONSISTENCIES...THE TIMING OF THESE WAVES IS STILL A BIT UNCERTAIN...SO KEPT BROAD BRUSHED THE PRECIPITATION CHANCES DURING THIS TIME FRAME. WITH MOST UNSTABLE CAPES LESS THAN 750 J/KG...KEPT THE THUNDERSTORM CHANCES AS ISOLATED. WHEN THE 0-3 KM TO 0-6 KM SHEAR DOES BECOME FAVORABLE FOR THE DEVELOPMENT OF SUPERCELLS...THERE IS VERY LITTLE INSTABILITY. AS A RESULT...NOT ANTICIPATING ANY SEVERE WEATHER. ON WEDNESDAY NIGHT...A STRONG CANADIAN COLD FRONT WILL MOVE SOUTH THROUGH THE FORECAST AREA. BEHIND THIS FRONT...850 MB TEMPERATURES WILL FALL INTO THE 0 TO -4C RANGE AND REMAIN IN THIS RANGE INTO THE WEEKEND. THIS IS NEARLY 2 STANDARD DEVIATIONS BELOW NORMAL. IT CONTINUES TO LOOK LIKE...HIGH TEMPERATURES WILL BE AROUND 60 ON THURSDAY...AND ONLY IN THE 50S FOR FRIDAY. WHILE THERE IS AGREEMENT IN THE ECMWF AND GFS ON THESE HIGH TEMPERATURES...THEY ARE STILL RUNNING 10 DEGREES APART ON THE LOW TEMPERATURES FOR THURSDAY NIGHT AND FRIDAY NIGHT. THE ECMWF HAS LOW TEMPERATURES AROUND 40 AND THEY ARE AROUND 30 IN THE GFS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1128 PM CDT FRI SEP 5 2014 HIGH PRESSURE BUILDING INTO THE TAF SITES FROM THE NORTHERN PLAINS OVER THE NEXT 24 HOURS WILL ALLOW A FEED OF DRY AIR TO CONTINUE... RESULTING IN VFR CONDITIONS. THERE REMAINS A LITTLE CONCERN FOR VALLEY FOG AT LSE THIS MORNING GIVEN THE TEMPERATURE/DEWPOINT SPREAD OF 4 F AT 04Z. HOWEVER...A PERSISTENT 10 TO 20 KT NORTHWEST BREEZE LOOKS TO EXIST RIGHT ABOVE LSE THROUGH THE ENTIRE EARLY MORNING HOURS...STRONG ENOUGH TO PREVENT VALLEY FOG FORMATION. THIS SAME BREEZE COULD RESULT IN A LITTLE GUSTINESS AT THE TAF SITES DURING THE AFTERNOON...BUT NOT HIGH ENOUGH TO MENTION IN THE TAFS AT THIS TIME. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM...BOYNE AVIATION...AJ
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
832 AM PDT SAT SEP 6 2014 .SYNOPSIS... SUBTROPICAL MOISTURE STREAMING NORTHWESTWARD OVER THE AREA WILL BRING INCREASING CHANCES FOR SHOWERS AND THUNDERSTORMS. ISOLATED ACTIVITY IS EXPECTED OVER THE MOUNTAINS THIS AFTERNOON...BECOMING MORE WIDESPREAD ON SUNDAY AND MONDAY. THE BEST CHANCES WILL BE IN THE MOUNTAINS AND DESERTS. A RICH MOISTURE SUPPLY WILL FUEL LOCALLY HEAVY RAINFALL AMOUNTS AND POSSIBLE FLASH FLOODING NEAR THE MOUNTAINS AND DESERTS. THE MONSOONAL FLOW WILL LIMIT THE MARINE LAYER INFLUENCE UNTIL TUESDAY...WHEN A LOW PRESSURE TROUGH WILL DIG DOWN THE WEST COAST WITH INCREASING ONSHORE FLOW. THE THREAT OF SHOWERS WILL DIMINISH ON TUE...WITH DRY...SEASONAL WEATHER FOR THE REMAINDER OF THE WEEK. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... VISIBLE SATELLITE IMAGERY EARLY THIS MORNING SHOWED THE LOWER CLOUDS MUCH MORE LIMITED THAN THE PAST COUPLE OF MORNINGS. A FEW CLOUDS WERE EVIDENT AROUND THE SALTON SEA...BUT MOST WERE HOVERING JUST OFFSHORE. WINDS WERE MOSTLY LIGHT AND SURFACE PRESSURE GRADIENTS WEAK...WITH A CONTINUED OFFSHORE TREND. BASED ON REMOTE OBSERVATIONS AND GPS DATA WITH PW VALUES AROUND 1.4 INCHES...A RICH MOISTURE SUPPLY EXISTS BELOW 4K FT IN THE LOWER DESERTS. THE 12Z MIRAMAR SOUNDING HAD QUITE A JUMP THIS MORNING AS WELL...TO 1.3 INCHES. A 7 DEGREE C INVERSION WAS BASED NEAR 1150 FT...CONSIDERABLY LOWER THAN YESTERDAY. THE SHALLOWER MARINE LAYER AND PLENTY OF SUN TODAY WILL BOOST TEMPERATURES WEST OF THE MOUNTAINS. MAX TEMPS IN THE INLAND EMPIRE WILL FLIRT WITH TRIPLE DIGITS...AND INLAND SAN DIEGO WILL BE WELL INTO THE 90S BY AFTERNOON. ALONG THE COAST...A WEAKER SEA BREEZE WILL ALLOW TEMPERATURES TO CLIMB INTO THE UPPER 70S AND 80S. OVER THE MOUNTAINS...HEATING SHOULD BE SUFFICIENT TO FIRE OFF CONVECTION ALONG THE HIGHER PEAKS. SOME OF THIS COULD DRIFT ALONG THE COASTAL FOOTHILLS AS WELL. THE LATEST RUN OF THE HIRES HRRR MODEL DOES INDICATE SOME CONVECTION OVER THE HIGHER PEAKS BUT OTHER RECENT MODEL RUNS ARE DRY. HURRICANE NORBERT CONTINUES TO MOVE SLOWLY TOWARD THE NW...JUST OFF THE PACIFIC COAST OF SOUTHERN BAJA. NORBERT STRENGTHENED TO A CATEGORY 3 HURRICANE LATE FRIDAY EVENING...ACHIEVING MAJOR HURRICANE STATUS. AT 8 AM PDT...HIGHEST SUSTAINED WINDS WERE 115 MPH. WEAKENING IS EXPECTED TO COMMENCE LATER TODAY THROUGH MON AS NORBERT MOVES OVER COOLER WATERS. THE REMNANTS ARE EXPECTED TO MOVE INLAND ACROSS NORTHERN BAJA ON TUE...WITH THE VARIOUS MODELS NOW COMING INTO BETTER AGREEMENT. IN THE MEANTIME PW WILL CONTINUE TO INCREASE ACROSS THE REGION THROUGH MON AS FLOW AROUND TROPICAL CYCLONE NORBERT TEAMS UP WITH THE MOISTURE FROM FORMER ATLANTIC TROPICAL CYCLONE DOLLY. THE MAIN CONCERN HERE IS WITH THE ANOMALOUSLY HIGH MOISTURE VALUES THAT WILL BE PRESENT OVER THE AREA BY SUN/MON...PARTICULARLY RIVERSIDE AND SAN DIEGO COUNTIES WITH VALUES FORECAST WELL IN EXCESS OF TWO INCHES. THIS MOISTURE INFLUX WILL BRING GREATER CLOUD COVER FOR SUN/MON WHICH WILL KEEP MAX TEMPS LOWER INLAND...BUT HUMIDITY WILL BE UP. WITH THE LEADING EDGE OF THE MOISTURE INFLUX...SHOWERS AND ISOLATED THUNDERSTORMS MAY DEVELOP LATE TONIGHT/SUN MORNING. THIS POSES A QUESTION ABOUT THE EXTENT AND PERSISTENCE OF CLOUD COVER ON SUN. THUNDERSTORM AND POSSIBLE MCS DEVELOPMENT LATER TODAY AND OVERNIGHT OVER THE LOWER COLORADO RIVER VALLEY MAY PLAY A ROLE AS WELL. WITHOUT AN OBVIOUS TRIGGER TO GENERATE THUNDERSTORMS...HEATING AND/ OR OUTFLOW BOUNDARIES FROM ACTIVITY TO THE EAST MAY BE NECESSARY TO GET STRONG LIFT AND EXCESSIVE RAINFALL AMOUNTS. IN ANY CASE...SHOWER CHANCES EXTEND ALL THE WAY TO THE COAST AS THE INFLUX OF MID-LEVEL MOISTURE ARRIVES...EVEN THOUGH MODEL PRECIP AMOUNTS HAVE BEEN SPOTTY AT BEST. GIVEN THE EXCESSIVE MOISTURE SUPPLY...WHERE THUNDERSTORMS DO DEVELOP...HEAVY RAINFALL AND FLASH FLOODING IS LIKELY TO FOLLOW. ISOLATED RAINFALL AMOUNTS EXCEEDING 3 INCHES LOOK POSSIBLE. STEERING LEVEL FLOW WILL BE RATHER WEAK...BUT MAINLY OUT OF THE SOUTH TO SE FOR SUNDAY. DEPENDING ON LATER MODEL RUNS AND AVAILABLE OBSERVATIONS...WE MAY NEED TO EXPAND THE FLASH FLOOD WATCH INTO THE VALLEYS. PW VALUES CONTINUE EXCESSIVE ON MON...WITH SLIGHTLY BETTER UPPER SUPPORT. DRYING WILL COMMENCE OVER NORTHERN PORTIONS OF THE CWA ON MON NIGHT AS THE UPPER TROUGH SAGS SOUTH ACROSS THE STATE. HOWEVER...HIGH PW VALUES ARE LIKELY TO PERSIST INTO TUE OVER PORTIONS OF SAN DIEGO COUNTY. DRY WEATHER AND SEASONAL TEMPERATURES ARE EXPECTED TO FOLLOW FOR THE REMAINDER OF THE WEEK. && .AVIATION... 061530Z...MOSTLY CLEAR THIS MORNING...EXCEPT FOR SOME PATCHY LOW CLOUDS WITH BASES AROUND 1000 FT MSL OVER COASTAL SAN DIEGO COUNTY. THESE CLOUDS SHOULD CLEAR BY 16Z. PATCHY LOW CLOUDS WITH BASES AROUND 1000 FT MSL AND TOPS TO 1500 FT COULD RETURN TO THE COASTAL AREAS AFT 06Z SUN...BUT ARE NOT LIKELY TO IMPACT TAF SITES WITH LOW CIGS AND REDUCED VIS. OTHERWISE...CLEAR WITH UNRESTRICTED VIS THIS MORNING BECOMING SCT 4000 FT MSL LAYERED TO 35000 FT THIS AFTERNOON. MOUNTAINS/DESERTS...SCT CLOUDS WITH BASES 3000-4000 FT MSL THIS MORNING IN THE COACHELLA VALLEY AND SAN DIEGO COUNTY DESERTS... FOLLOWED BY A CHANCE OF SHOWERS AND THUNDERSTORMS WITH BASES 6000-8000 FT MSL LAYERED TO 35000-40000 FT AFT 18Z. THUNDERSTORMS MAY PRODUCE GUSTY/ERRATIC DOWNDRAFT WINDS...SMALL HAIL AND LOCALLY REDUCED VIS IN HEAVY RAIN. OTHERWISE...UNRESTRICTED VIS THROUGH THIS EVENING. && .MARINE... 830 AM...THERE IS A SLIGHT CHANCE OF THUNDERSTORMS OVER THE COASTAL WATERS SUNDAY AND MONDAY FROM THE REMNANTS OF TROPICAL CYCLONE NORBERT. && .BEACHES... 830 AM...A LONG-PERIOD SOUTHWEST SWELL ORIGINATING IN THE SOUTHERN HEMISPHERE WILL CONTINUE TO GENERATE ELEVATED SURF ON SOUTH AND SOUTHWEST FACING BEACHES THROUGH TONIGHT. THIS SWELL WILL SUBSIDE SUNDAY INTO MONDAY. HOWEVER...A 4-6 FOOT/9-12 SECOND SOUTH-SOUTHEAST SWELL GENERATED BY TROPICAL CYCLONE NORBERT WILL LIKELY ARRIVE EARLY SUNDAY MORNING AND CONTINUE THROUGH MONDAY. THE SURF HEIGHTS AND LARGE TIDAL SWINGS WILL RESULT IN STRONG AND DANGEROUS RIP AND LONGSHORE CURRENTS. THERE IS ALSO THE POTENTIAL FOR MINOR TIDAL OVERFLOW DURING HIGH TIDES. A BEACH HAZARDS STATEMENT IS IN EFFECT THROUGH MONDAY NIGHT...SEE LAXCFWSGX AND LAXSRFSGX FOR MORE DETAILS. && .SKYWARN... SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...FLASH FLOOD WATCH FROM SUNDAY MORNING THROUGH MONDAY EVENING FOR THE APPLE AND LUCERNE VALLEYS...COACHELLA VALLEY... RIVERSIDE COUNTY MOUNTAINS...SAN BERNARDINO COUNTY MOUNTAINS...SAN DIEGO COUNTY DESERTS...SAN DIEGO COUNTY MOUNTAINS. BEACH HAZARDS STATEMENT THROUGH LATE MONDAY NIGHT FOR THE BEACHES IN THE ORANGE COUNTY COASTAL AREAS...SAN DIEGO COUNTY COASTAL AREAS. PZ...NONE. && $$ PUBLIC...JAD AVIATION/MARINE/BEACHES...PG Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 1055 AM CDT Sat Sep 6 2014 .UPDATE... ISSUED AT 1051 AM CDT SAT SEP 6 2014 Persistent stratus deck behind the frontal boundary that passed through last night very slow to clear. Concerned for the high temps in the far SE. In the last couple hours, the clouds have started to progress slightly to the SE and less concerned with the highs in the NW, but still have a ways to go with temps lingering in the 60s through mid morning. Will only make slight adjustments in the NW...possibly a couple degrees in the SE. Some minor and sct showers remain in the far SE and see no reason to pull the mention, and will continue to adjust to trends. Updates out momentarily. && .SHORT TERM...(Today) ISSUED AT 259 AM CDT SAT SEP 6 2014 Despite passage of a cold front during the evening hours, scattered light showers persist across the southern two-thirds of the KILX CWA early this morning. NAM/GFS/ECMWF have all verified too far north with lingering precip field at 06z, while the latest HRRR seems to have the best handle on the current situation. Following the latest radar trends and HRRR solution, have maintained low chance PoPs along/south of I-70 into the early afternoon before showers gradually push further southward into the Ohio River Valley. Meanwhile further north, have gone with a dry forecast across the remainder of the CWA. Skies will start out mostly cloudy, followed by a steady clearing trend from north to south as the day progresses. Afternoon high temperatures will be quite a bit cooler than yesterday, with readings remaining in the lower to middle 70s. && .LONG TERM...(Tonight through Friday) ISSUED AT 259 AM CDT SAT SEP 6 2014 High pressure will build into the region tonight into Sunday, resulting in clear skies and cool temperatures. Light winds/dry airmass will allow excellent radiational cooling to take place tonight, with lows bottoming out in the lower to middle 50s. On the flip side, full sunshine acting on the dry airmass will help temperatures rebound nicely into the middle to upper 70s on Sunday. Once the upper trough responsible for the cool weather lifts into eastern Canada, an active zonal flow pattern will develop across the CONUS next week. Two distinct systems will track through this flow, bringing rain chances to central Illinois. The first is progged to track from the Northern Plains Sunday night into the southern Great Lakes by Tuesday morning. Models are developing showers/storms in advance of this feature Monday night as low-level jet focuses across northern Missouri/southern Iowa. Solutions vary as to how far east into the prevailing surface ridge axis precip will penetrate late Monday night into Tuesday. Given presence of very dry airmass initially and only weak upper support with the short-wave, will keep highest PoPs confined to the Illinois River Valley Monday night. Further east, will go with a dry forecast along/east of I-57. Will only mention low chance PoPs on Tuesday as nocturnal convection undergoes diurnal weakening further eastward into the dry airmass. Second stronger wave will approach Tuesday night into Wednesday, bringing a much better chance for widespread rain. Models are suggesting moisture from tropical system in the Pacific may get drawn into this feature, resulting in unseasonably high precipitable water values in excess of 2 inches. GFS/ECMWF/GEM all bring a hefty slug of precip into Illinois late Tuesday night into Wednesday accordingly: however, axis of heaviest precip still remains in question. Have boosted PoPs to likely across the northern two-thirds of the CWA Tuesday night and Wednesday. Initial QPF from WPC indicates the potential for 1 to 2 inches of rain across much of the area during this time, with the highest amounts across the Illinois River Valley. Once wave passes to the east, strong cold front will settle southward, taking the higher rain chances into the far southern CWA Wednesday night. After that, most model guidance is advertising a cooler/drier day on Thursday followed by a shot of even cooler air by the end of the week. Both the GFS and ECMWF show 850mb temps dropping to around 0c by next Saturday morning, potentially resulting in highs only in the middle to upper 60s and lows dipping into the 40s next weekend. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) ISSUED AT 600 AM CDT SAT SEP 6 2014 Areas of MVFR and local IFR cigs will give way to VFR conditions later this morning across the entire area as high pressure builds in from the northwest. Band of stratus continues to edge slowly to the southeast this morning with a large area mid level clouds generally above 12000 feet remaining. The mid cloud band will also slowly pull away from the area later this morning into the early afternoon hours. Forecast soundings suggest cumulus to develop across the forecast area by early afternoon with bases of 3000-4000 feet which should dissipate by late afternoon. Surface winds will remain out of a northerly direction today with speeds in the 8 to 13 kt range. Tonight, as the large area of high pressure settles in, look for nearly calm winds to prevail. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HJS SHORT TERM...BARNES LONG TERM...BARNES AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
642 AM CDT SAT SEP 6 2014 .DISCUSSION... 313 AM CDT THE COLD FRONT ASSOCIATED WITH THE ACTIVE WEATHER ON FRIDAY HAS PUSHED OFF TO THE SOUTHEAST EARLY THIS MORNING. WE STILL HAVE SOME SHOWERS FIRING IN CENTRAL ILLINOIS AND EXTENDING INTO PORTIONS OF NORTHEAST ILLINOIS AND NORTHWEST INDIANA. IT IS THIS AREA WHERE THE LOW TO MID LEVEL BAROCLINIC ZONE STILL LINGERS AS SOME ENERGY GLIDES EASTWARD THROUGH THE BASE OF THE UPPER TROUGH AXIS MOVING THROUGH WESTERN ONTARIO AND EXTENDING INTO THE PORTIONS OF THE MIDWEST. UPPER AIR SOUNDINGS AND WATER VAPOR CONFIRM THE DRIER AIR MASS SET TO INVADE OUR AREA THIS WEEKEND. KMPX 0Z SOUNDING DEPICTED A 1.2 IN PRECIPITABLE WATER DROP IN THE LAST 24 HOURS...AND LOW TO MID 50S DEWPOINTS HAVE ALREADY PUSHED INTO NORTH CENTRAL ILLINOIS. EXPECT THAT TREND TO CONTINUE OVER THE REMAINDER OF THE AREA TODAY. THE BAROCLINIC ZONE WILL CONTINUE TO PRESS EAST AS DRIER NORTHERLY FLOW SETS IN...WITH RAIN SHOWERS MOVING ALONG WITH IT. THE CLOUD SHIELD WILL EVENTUALLY PUSH EASTWARD AS A DRY SHEARED VORTICITY AREA SLIDES ON BY AND SURFACE HIGH PRESSURE IN THE CENTRAL PLAINS HEADS INTO IOWA WITH THE RIDGE AXIS EXTENDING TO THE SOUTHERN GREAT LAKES. HIGHS TOP OFF IN THE LOWER TO MAYBE MID 70S WITH INCREASING SUNSHINE THROUGH THE AFTERNOON. DEWPOINTS WILL BE SOME 15 DEGREES LOWER THAN FRIDAY...MAKING FOR A COMFORTABLE IF NOT "COOL" DAY. EXPECT A LAKE BREEZE TO LIMIT THE WARM UP DOWNTOWN. ON SUNDAY THE FLOW ALOFT IS FAIRLY ZONAL ACROSS MUCH OF THE COUNTRY WITH NO NOTICEABLE VORT MAXES. MEANWHILE SURFACE HIGH PRESSURE BUILDS OVER THE GREAT LAKES BY MIDDAY THEN OFF TO THE EASTERN GREAT LAKES BY MONDAY MORNING. THIS WILL MAKE FOR ANOTHER DELIGHTFUL EARLY METEOROLOGICAL AUTUMN AFTERNOON WITH PLENTIFUL SUNSHINE...MILD AND DRY CONDITIONS. AND WINDS WILL BE ON THE LIGHTER SIDE TOO. HIGHS WILL TOP OFF IN THE MID 70S..UP A FEW DEGREES FROM SATURDAY. THE NEXT REAL FORCING WILL BE EMANATING FROM A CURRENTLY RETROGRADING CUTOFF LOW OFF THE NORTHERN CALIFORNIA COAST...WITH ENERGY EVENTUALLY MIGRATING EASTWARD IN THE UPPER JET. AS SURFACE HIGH PRESSURE CONTINUES EAST...RETURN FLOW DEVELOPS IN THE PLAINS INCREASING MOISTURE TRANSPORT TO OUR WEST. MEDIUM RANGE MODELS A SUBTLE WAVE THAT COMBINED WITH INCREASED WARM ADVECTION IN IOWA THAT LOOKS TO INITIATE CONVECTION LATER MONDAY. AS THE WAVE TRACKS EASTWARD...SOME DIFFERENCES EMERGE AS TO WHETHER THUNDERSTORMS WILL MAKE IT INTO NORTHEAST ILLNOIS AS THE GFS SUGGESTS OR LARGELY GRAZE THE AREA LIKE THE EC/NAM. RECENT HISTORY HAS SHOWN THESE SUBTLE SYSTEMS MAKING BETTER EASTWARD PROGRESS THAN ANTICIPATED...SO WILL CONTINUE WITH CHANCE POPS UNTIL GUIDANCE LATCHES ON TO SOMETHING MORE DEFINITIVE. ON TUESDAY...THE LEE TROUGHING THAT DEVELOPS AHEAD OF THIS FIRST WAVE EVENTUALLY GETS A SHOVE EAST AS THE MEAN TROUGH IN THE WEST GETS SOME MOVEMENT. A SHARP UPPER TROUGH WILL REMAIN WELL NORTH IN CANADA...BUT SOME OF THE COOLER CANADIAN AIR LOOKS TO GET DISLODGED A WILL DEVELOP A COLD FRONT ALONG THE INTERNATIONAL BORDER THAT WILL SHIFT INTO MINNESOTA. MODELS/ENSEMBLES THEN DEVELOP A DECENT EARLY AUTUMN SURFACE LOW THAT WILL TRACK ALONG THIS BOUNDARY SOMEWHERE THROUGH THE GREAT LAKES REGION INTO WEDNESDAY. MODELS GENERALLY AGREE ON THE TIMING BUT VARY CONSIDERABLY ON THE STRENGTH OF THE LOW THAT DEVELOPS. THERE ARE HINTS THAT SOME OF THE MOISTURE FROM HURRICANE NORBERT OFF OF BAJA CALIFORNIA MAY GET EMBEDDED IN THE WESTERLY FLOW. EITHER WAY...THE LOW LEVEL WIND FIELD RESPONDS AND COMBINES WITH A NICE FEED OF MOISTURE (PW`S > 2"). FORECAST SOUNDINGS DEPICT A DEEP MOIST COLUMN SUGGESTIVE OF SHOWERS WITH EMBEDDED THUNDERSTORMS WITH A HEAVY RAINFALL POTENTIAL. HAVE PUT IN LIKELY POPS FOR THE TUESDAY NIGHT INTO WEDNESDAY MORNING PERIOD TO ACCOUNT FOR DECENT MODEL AGREEMENT AT THIS TIME THOUGH A NUMBER OF UPSTREAM DEPENDENCIES WILL INFLUENCE THE TRACK AND STRENGTH OF THIS SYSTEM. THE WESTERN UPPER TROUGH WILL BE LAGGING BEHIND THIS SHORTWAVE TROUGH AND WILL SLOWLY PROGRESS THROUGH FOR THE LATTER HALF OF THE WEEK...LEADING TO BELOW NORMAL TEMPERATURES AND SMALL CHANCES FOR RAIN SHOWERS. SURFACE HIGH PRESSURE SHOULD BE REDEVELOPING DURING THIS TIME AND THUS THE LOWER PRECIP POTENTIAL. KMD && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 12Z... * NORTH-NORTHWEST WINDS AROUND 10 KT...LIKELY SHIFTING NORTHEAST AT MDW THIS AFTERNOON WITH LAKE BREEZE. LESS LIKELY TO SHIFT AT ORD. RATZER //DISCUSSION...UPDATED 12Z... LOW LEVELS CONTINUE TO DRY OUT WITH NORTH-NORTHWEST WINDS THIS MORNING. A FEW PATCHES OF 2500-3000 FT MVFR LINGER SOUTH OF KMDW AND TOWARDS KGYY...THOUGH THESE SHOULD BE DISSIPATING QUICKLY THIS MORNING WITH VFR CONDITIONS EXPECTED FOR THE REMAINDER OF THE TAF PERIOD. ONLY REAL CONCERN IS WITH THE POTENTIAL FOR A LAKE BREEZE WIND SHIFT THIS AFTERNOON ACROSS MAINLY KMDW AND KGYY. HIGH-RES GUIDANCE TRENDS CONTINUE TO INDICATE KORD TO REMAIN NORTH- NORTHWEST IN 340-360 DEGREE RANGE WHILE WINDS SHIFT TO 010-030 DEGREES AT KMDW AND KGYY. SPEEDS AROUND/SLIGHTLY OVER 10 KT THROUGH MIDDAY AS HIGH PRESSURE BUILDS TOWARD THE REGION...THEN SLACKING THIS AFTERNOON AS GRADIENT WEAKENS IN THE VICINITY OF THE SURFACE RIDGE. WILL HAVE TO WATCH LAKE BREEZE FOR IMPACT ON KORD BUT HAVE KEPT WIND SHIFT EAST OF THERE BASED ON STRONGER GRADIENT WINDS THIS MORNING AND CONTINUED GUIDANCE TRENDS INDICATING NO LAKE BREEZE PASSAGE. OTHERWISE...WINDS DIMINISH QUICKLY EARLY THIS EVENING AND ASSUME A VARIABLE/WESTERLY DIRECTION LESS THAN 5 KT. COULD BE SOME PATCHY MVFR FOG MAINLY OUTSIDE METRO CHICAGO. RATZER //ORD AND MDW CONFIDENCE...UPDATED 12Z... * MEDIUM CONFIDENCE IN LAKE BREEZE TIMING/INLAND EXTENT. * HIGH CONFIDENCE ALL OTHER ELEMENTS. RATZER //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT THROUGH MONDAY...VFR. SLGT CHANCE TSRA LATE MONDAY NIGHT. TUESDAY THROUGH THURSDAY...PERIODIC CHANCES OF SHRA/TSRA... ESPECIALLY TUESDAY NIGHT INTO WEDNESDAY. FRIDAY...VFR. RATZER && .MARINE... 259 AM CDT HIGH PRESSURE OVER THE CENTRAL PLAINS WILL MOVE SLOWLY EAST INTO THE MIDWEST TONIGHT AND ACROSS THE LOWER LAKES BY SUNDAY NIGHT. BRIEF PERIOD OF GUSTY NORTH-NORTHWEST WINDS TO 25 KT THIS MORNING AS THE SURFACE HIGH DEVELOPS TOWARD THE LAKE SHOULD RELAX THIS AFTERNOON ESPECIALLY ON SOUTHERN LAKE MICHIGAN WHERE THE RIDGE AXIS WILL RESIDE BY EVENING. FARTHER NORTH...A WEAK LOW WILL PASS ACROSS THE NORTHERN LAKES TONIGHT...BACKING WINDS MORE WESTERLY WITH GUSTS 20-25 KT AGAIN AHEAD OF A WEAK COLD FRONT THIS AFTERNOON...THEN VEERING NORTH TOWARD EVENING AND DIMINISHING. WINDS WILL COME BACK AROUND TO THE SOUTH-SOUTHEAST SUNDAY AND SUNDAY NIGHT AS THE HIGH DRIFTS OFF TO THE EAST ACROSS THE LOWER LAKES INTO NEW ENGLAND. WINDS LOOK TO REMAIN FAIRLY MODEST FROM THE SOUTH EARLY IN THE WEEK WHILE LOW PRESSURE DEVELOPS OVER THE PLAINS. THIS LOW IS EXPECTED TO DEEPEN AND EVENTUALLY TRACK TOWARD THE WESTERN LAKES BY MID-WEEK. THE EXACT TRACK REMAINS A LITTLE UNCERTAIN AT THIS POINT...THOUGH MOST MODEL GUIDANCE BRINGS THE LOW ACROSS IOWA INTO WISCONSIN OR NORTHERN ILLINOIS ON WEDNESDAY...BEFORE SOLUTIONS DIVERGE. IN EITHER CASE...WINDS ARE EXPECTED TO BACK SOUTHEAST-EAST AND INCREASE AS THE GRADIENT TIGHTENS UP IN ADVANCE OF THE LOW TUESDAY NIGHT INTO EARLY WEDNESDAY. NORTH-NORTHWEST WINDS AROUND 20 KT THIS MORNING PRODUCING 4-5 FOOTERS AT BUOYS ALONG THE SOUTH/SOUTHEAST SHORE. SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT THROUGH THIS AFTERNOON FOR THE INDIANA NEARSHORE WATERS. WINDS DIMINISH AND BACK QUICKLY TOWARD EVENING WHICH SHOULD ALLOW WAVES TO SUBSIDE FAIRLY QUICKLY BY EVENING. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 7 PM SATURDAY. LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 7 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 615 AM CDT Sat Sep 6 2014 .SHORT TERM...(Today) ISSUED AT 259 AM CDT SAT SEP 6 2014 Despite passage of a cold front during the evening hours, scattered light showers persist across the southern two-thirds of the KILX CWA early this morning. NAM/GFS/ECMWF have all verified too far north with lingering precip field at 06z, while the latest HRRR seems to have the best handle on the current situation. Following the latest radar trends and HRRR solution, have maintained low chance PoPs along/south of I-70 into the early afternoon before showers gradually push further southward into the Ohio River Valley. Meanwhile further north, have gone with a dry forecast across the remainder of the CWA. Skies will start out mostly cloudy, followed by a steady clearing trend from north to south as the day progresses. Afternoon high temperatures will be quite a bit cooler than yesterday, with readings remaining in the lower to middle 70s. && .LONG TERM...(Tonight through Friday) ISSUED AT 259 AM CDT SAT SEP 6 2014 High pressure will build into the region tonight into Sunday, resulting in clear skies and cool temperatures. Light winds/dry airmass will allow excellent radiational cooling to take place tonight, with lows bottoming out in the lower to middle 50s. On the flip side, full sunshine acting on the dry airmass will help temperatures rebound nicely into the middle to upper 70s on Sunday. Once the upper trough responsible for the cool weather lifts into eastern Canada, an active zonal flow pattern will develop across the CONUS next week. Two distinct systems will track through this flow, bringing rain chances to central Illinois. The first is progged to track from the Northern Plains Sunday night into the southern Great Lakes by Tuesday morning. Models are developing showers/storms in advance of this feature Monday night as low-level jet focuses across northern Missouri/southern Iowa. Solutions vary as to how far east into the prevailing surface ridge axis precip will penetrate late Monday night into Tuesday. Given presence of very dry airmass initially and only weak upper support with the short-wave, will keep highest PoPs confined to the Illinois River Valley Monday night. Further east, will go with a dry forecast along/east of I-57. Will only mention low chance PoPs on Tuesday as nocturnal convection undergoes diurnal weakening further eastward into the dry airmass. Second stronger wave will approach Tuesday night into Wednesday, bringing a much better chance for widespread rain. Models are suggesting moisture from tropical system in the Pacific may get drawn into this feature, resulting in unseasonably high precipitable water values in excess of 2 inches. GFS/ECMWF/GEM all bring a hefty slug of precip into Illinois late Tuesday night into Wednesday accordingly: however, axis of heaviest precip still remains in question. Have boosted PoPs to likely across the northern two-thirds of the CWA Tuesday night and Wednesday. Initial QPF from WPC indicates the potential for 1 to 2 inches of rain across much of the area during this time, with the highest amounts across the Illinois River Valley. Once wave passes to the east, strong cold front will settle southward, taking the higher rain chances into the far southern CWA Wednesday night. After that, most model guidance is advertising a cooler/drier day on Thursday followed by a shot of even cooler air by the end of the week. Both the GFS and ECMWF show 850mb temps dropping to around 0c by next Saturday morning, potentially resulting in highs only in the middle to upper 60s and lows dipping into the 40s next weekend. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) ISSUED AT 600 AM CDT SAT SEP 6 2014 Areas of MVFR and local IFR cigs will give way to VFR conditions later this morning across the entire area as high pressure builds in from the northwest. Band of stratus continues to edge slowly to the southeast this morning with a large area mid level clouds generally above 12000 feet remaining. The mid cloud band will also slowly pull away from the area later this morning into the early afternoon hours. Forecast soundings suggest cumulus to develop across the forecast area by early afternoon with bases of 3000-4000 feet which should dissipate by late afternoon. Surface winds will remain out of a northerly direction today with speeds in the 8 to 13 kt range. Tonight, as the large area of high pressure settles in, look for nearly calm winds to prevail. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...BARNES LONG TERM...BARNES AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS JACKSON KY
1149 AM EDT SAT SEP 6 2014 .UPDATE... ISSUED AT 1148 AM EDT SAT SEP 6 2014 LATEST MESOANALYSIS SHOWS WEAK SURFACE CONVERGENCE ACROSS THE CENTRAL PART OF THE FORECAST AREA. THIS IS AHEAD OF THE APPROACHING COLD FRONT WHICH HAS MOVED INTO NORTHERN KY. SBCAPE IN EXCESS OF 2500 J/KG ALSO ACROSS THE CENTRAL PART OF THE FORECAST AREA. CURRENT THINKING IS THAT CONVECTION WILL INITIATE EARLY THIS AFTERNOON WHERE THE LOW LEVEL CONVERGENCE COINCIDES WITH THE GREATEST CAPE. THIS IDEA IS ALSO SUPPORTED BY THE 14Z HRRR. HAVE ADJUSTED NDFD AND ASSOCIATED FORECAST PRODUCTS ACCORDINGLY. THERE IS ALSO SOME RAIN OCCURRING BEHIND THE FRONT...AND THE 12Z NAM AND 14Z HRRR BRING PRECIPITATION INTO THE NORTHERN PART OF THE FORECAST AREA AS WELL...EVEN THOUGH THE INITIAL CONVECTIVE DEVELOPMENT THROUGH MID AFTERNOON SHOULD BE FOCUSED IN THE CENTRAL PART OF THE FORECAST AREA. ONCE SHOWERS AND THUNDERSTORMS DEVELOP THIS AFTERNOON CURRENT STORM MOTION FORECAST WILL RESULT IN MOVEMENT TO THE SOUTHEAST AT 10 TO 15 MPH. UPDATE ISSUED AT 953 AM EDT SAT SEP 6 2014 UPDATED HOURLY NDFD BASED ON LATEST OBSERVATIONAL AND MODEL TRENDS. HAVE LOWERED THUNDERSTORM CHANCES FOR THE NEXT COUPLE OF HOURS FOLLOWING THE LATEST HRRR AND SATELLITE AND RADAR TRENDS. LOCALLY DENSE FOG HAS LIFTED AND HAVE UPDATED ZFP TO REMOVE MENTION OF MORNING FOG. 12Z SOUNDINGS SHOWING PWS OF AROUND 1.6 INCHES SO LOCALLY HEAVY RAINS STILL LOOK POSSIBLE AS NOTED IN THE HWO. UPDATE ISSUED AT 730 AM EDT SAT SEP 6 2014 DID A QUICK UPDATE TO THE GRIDS TO REFLECT THE CURRENT RADAR OBSERVATIONS AND TRENDS WITH RESPECT TO POPS AND WX. THE LATEST HRRR DOESN/T REALLY GET THINGS GOING AROUND HERE UNTIL AFTER 18Z SO HAVE TRENDED TOWARD THAT IDEA. ALSO...FINE TUNED THE T/TD ONES PER THE OBS AND TRENDS. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 350 AM EDT SAT SEP 6 2014 07Z SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE MOVING THROUGH EASTERN CANADA WITH A TRAILING COLD FRONT RUNNING SOUTHWEST THROUGH THE OHIO VALLEY AND INTO SOUTHERN MISSOURI. THE REMAINS OF A SQUALL LINE HAS SETTLED JUST SOUTH OF THE OHIO RIVER...OUT AHEAD OF THE COLD FRONT. A FEW LINGERING SHOWERS REMAIN WITH THIS AS IT CONTINUES TO FADE OUT WITH ITS APPROACH TO THE JKL CWA. ON SATELLITE...MID AND HIGH LEVEL CLOUDS COVER THE OHIO VALLEY NORTH AND WEST OF THIS OUTFLOW BOUNDARY. HOWEVER...THE CLEARER SKIES TO THE SOUTH HAS ALLOWED AREAS OF FOG TO DEVELOP THROUGH EAST KENTUCKY WITH LOCALLY DENSE PATCHES IN THE VALLEYS. HIGH DEWPOINTS IN THE UPPER 60S AND LOWER 70S ARE PROVIDING A FLOOR TO THE COOLING THIS NIGHT WITH JUST A SMALL RIDGE AND VALLEY SPLIT EVIDENT WITH READINGS VARYING FROM LOWER 70S IN THE THERMAL BELT TO THE UPPER 60S IN THE LOW SPOTS. WINDS REMAIN LIGHT TO CALM THROUGH THE AREA. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM AS HEIGHTS FALL OVER THE OHIO VALLEY IN RESPONSE TO A BROAD TROUGH MOVING THROUGH THE NORTHEAST PORTION OF THE CONTINENT. THE ENERGY STREAM ASSOCIATED WITH THIS MOVES QUICKLY INTO THE SOUTHERN OHIO VALLEY TODAY...BUT THEN LINGERS OVERHEAD THROUGH THE WEEKEND WITH A BIT OF A RESURGENCE LATER SUNDAY. GIVEN THE GOOD MODEL AGREEMENT... FOR WEATHER SPECIFICS HAVE FAVORED A BLEND OF THE HRRR AND NAM12 THROUGH THE FIRST HALF OF THE SHORT TERM FOLLOWED BY A MIX OF THE NAM AND LATEST ECMWF SOLUTIONS. SENSIBLE WEATHER WILL FEATURE AREAS OF FOG...LOCALLY DENSE...BURNING OFF EARLY THIS MORNING. THIS WILL BE FOLLOWED BY THE ARRIVAL OF SHOWERS AND THUNDERSTORMS BY MID AFTERNOON FROM NORTH TO SOUTH AS A COLD FRONT PRESSES SOUTH INTO THE AREA. PWS WITH THIS CONVECTION WILL BE MODERATELY HIGH WHILE STORM MOTION STARTS TO SPEED UP AS THE DAY WEARS ON. THIS SHOULD LIMIT THE RISK FOR FLASH FLOODING WHEN COMPARED TO THE PAST SEVERAL DAYS. HOWEVER...A LOCALIZED THREAT FOR HEAVY RAIN WILL REMAIN SHOULD TRAINING DEVELOP IN ANY PARTICULARLY LOCATION. THE THUNDER IS ANTICIPATED TO FADE FROM THE CONVECTION LATER TONIGHT AS THE FRONT SINKS SOUTH OF AREA LEAVING JUST A FEW LIGHT SHOWERS TRAILING BEHIND. FOR SUNDAY...THE NEARBY FRONT MAY CAUSE A SHOWER OR TWO TO POP UP OVER FAR SOUTHEAST KENTUCKY WHILE THE BOUNDARY SLOWS IN RESPONSE TO A BUCKLE IN THE MID LEVEL FLOW AND A DEVELOPING WAVE AT THE SFC ALONG THE GEORGIA COAST. THE WARMTH AND STICKY HUMIDITY WILL LEAVE THE AREA...AT LEAST FOR A COUPLE OF DAYS...ONCE THE FRONT MOVES THROUGH MEANING THAT SUNDAY WILL BE A MUCH MORE COMFORTABLE DAY THAN TODAY AND ALSO PROVIDE A HINT OF THE FALL-LIKE WEATHER THAT COULD ARRIVE IN EARNEST LATER IN THE WEEK. FOR TEMPERATURES...DEWPOINTS...AND WINDS...USED THE CONSSHORT FOR THE FIRST 24 HOURS AND THEN THE SUPERBLEND THROUGH SUNDAY. DID MAKE SOME MINOR ADJUSTMENTS FOR TERRAIN DIFFERENCES WITH TEMPS TONIGHT. AS FOR POPS ENDED UP ON THE HIGH SIDE OF MOS GUIDANCE TODAY...COUNTING ON MOST OF THE AREA MEASURING AS THIS FRONT MOVES THROUGH GIVEN THE FAIRLY HIGH MOISTURE CONTENT IN PLACE. WAS SIMILAR TO THE GUIDANCE TONIGHT AND SUNDAY...LIMITING THE CHANCE POPS TO THE FAR SOUTHEAST. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 335 AM EDT SAT SEP 6 2014 THE MODELS CONTINUE TO BE IN GOOD AGREEMENT IN REGARDS TO A SIGNIFICANT PATTERN CHANGE FOR THE END OF NEXT WEEK...WITH A MAJOR COOL DOWN IN STORE. HOWEVER...THE MODELS DIFFER IN HOW THEY HANDLE THE EVOLUTION OF WEATHER SYSTEMS THAT WILL BRING SHOWERS AND STORMS TO EASTERN KENTUCKY DURING THE UPCOMING WORK WEEK. THE PERIOD WILL START OUT WARM AND DRY AS HIGH PRESSURE SUNDAY NIGHT THROUGH TUESDAY. THERE IS A POSSIBILITY OF SCATTERED SHOWERS AND STORMS FORMING BENEATH THE RIDGE ON MONDAY...AS MOISTURE OFF THE GULF OF MEXICO GETS DRAWN INTO THE AREA BY A WEAK AREA OF LOW PRESSURE THAT IS PROGGED TO PASS ACROSS THE TENNESSEE VALLEY. THE ECMWF WAS SLOWER AND WETTER THAN THE GFS FROM WEDNESDAY ONWARD. BOTH MODELS HAVE A COLD FRONT MOVING ACROSS THE OHIO AND TENNESSEE VALLEY REGIONS WEDNESDAY THROUGH FRIDAY...WITH SCATTERED SHOWERS AND STORMS FORMING IN THE VICINITY OF THE BOUNDARY. WITH UNCERTAINTY BETWEEN THE MODELS...DECIDED TO USE A BLEND OF THE ECMWF AND GFS MODELS...WITH A SLIGHT BIAS TOWARD TO NORMALLY MORE RELIABLE ECMWF SOLUTION. THE BEST CHANCES FOR RAIN WILL COME FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY EVENING DURING FRONTAL PASSAGE. TEMPERATURES THE FIRST FEW DAYS OF THE PERIOD LOOK TO BE AT OR SLIGHT BELOW NORMAL...DUE TO THE INFLUENCE OF NORTHERLY FLOW...CLOUD COVER...AND PRECIPITATION ASSOCIATED WITH AN AREA OF LOW PRESSURE THAT IS EXPECTED TO PASS THROUGH THE TENNESSEE VALLEY ON MONDAY. HIGHS ON MONDAY ARE EXPECTED TO TOP OUT AROUND 80...WITH READINGS MAXING OUT IN THE LOW TO MID 80S ON TUESDAY AND WEDNESDAY. THE BIG PATTERN CHANGE LOOKS LIKE IT WILL TAKE PLACE FROM THURSDAY ONWARD...AS A COOL CANADIAN AIR MASS SETTLES OVER THE REGION BEHIND A DEPARTING AND VERY POTENT COLD FRONT. HIGHS ON FRIDAY MIGHT ONLY TOP OUT IN THE LOW TO MID 70S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 755 AM EDT SAT SEP 6 2014 THE FOG AT THE TAF SITES WILL LIFT AND DISSIPATING BY 1330Z. BEST CHANCES OF CONVECTION SHOULD HOLD OFF UNTIL AT LEAST 15Z ACROSS THE OFFICIAL TAF SITES TODAY...AWAITING THE NEARING APPROACH OF THE COLD FRONT. WITH THE HIGH PROBABILITIES OF CONVECTION ALONG THE FRONT...WENT WITH PREVAILING TSRA AND WITH THE LOWER...MVFR... VIS/CIGS STARTING AT 15Z AT THE FARTHEST NW SITE /KSYM/...AND 17Z AT THE SOUTHERN MOST SITE /KSME/ TO MATCH UP WITH ONGOING LIKELY TO CATEGORICAL POPS IN THE FORECAST. JUST SOME SCATTERED SHOWERS FOLLOW LATER THIS EVENING AT THE SITES WITH CIGS EXPECTED TO REMAIN IN THE MVFR RANGE POST-FRONTAL. WINDS THROUGH THE BULK OF THE PERIOD WILL BE LIGHT AND VARIABLE BUT SWITCH TO THE NORTH AND NORTHWEST AT 5 TO 10 KTS BEHIND THE FRONT AS IT DROPS SOUTH DURING THE DAY. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SBH SHORT TERM...GREIF LONG TERM...AR AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS JACKSON KY
953 AM EDT SAT SEP 6 2014 .UPDATE... ISSUED AT 953 AM EDT SAT SEP 6 2014 UPDATED HOURLY NDFD BASED ON LATEST OBSERVATIONAL AND MODEL TRENDS. HAVE LOWERED THUNDERSTORM CHANCES FOR THE NEXT COUPLE OF HOURS FOLLOWING THE LATEST HRRR AND SATELLITE AND RADAR TRENDS. LOCALLY DENSE FOG HAS LIFTED AND HAVE UPDATED ZFP TO REMOVE MENTION OF MORNING FOG. 12Z SOUNDINGS SHOWING PWS OF AROUND 1.6 INCHES SO LOCALLY HEAVY RAINS STILL LOOK POSSIBLE AS NOTED IN THE HWO. UPDATE ISSUED AT 730 AM EDT SAT SEP 6 2014 DID A QUICK UPDATE TO THE GRIDS TO REFLECT THE CURRENT RADAR OBSERVATIONS AND TRENDS WITH RESPECT TO POPS AND WX. THE LATEST HRRR DOESN/T REALLY GET THINGS GOING AROUND HERE UNTIL AFTER 18Z SO HAVE TRENDED TOWARD THAT IDEA. ALSO...FINE TUNED THE T/TD ONES PER THE OBS AND TRENDS. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 350 AM EDT SAT SEP 6 2014 07Z SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE MOVING THROUGH EASTERN CANADA WITH A TRAILING COLD FRONT RUNNING SOUTHWEST THROUGH THE OHIO VALLEY AND INTO SOUTHERN MISSOURI. THE REMAINS OF A SQUALL LINE HAS SETTLED JUST SOUTH OF THE OHIO RIVER...OUT AHEAD OF THE COLD FRONT. A FEW LINGERING SHOWERS REMAIN WITH THIS AS IT CONTINUES TO FADE OUT WITH ITS APPROACH TO THE JKL CWA. ON SATELLITE...MID AND HIGH LEVEL CLOUDS COVER THE OHIO VALLEY NORTH AND WEST OF THIS OUTFLOW BOUNDARY. HOWEVER...THE CLEARER SKIES TO THE SOUTH HAS ALLOWED AREAS OF FOG TO DEVELOP THROUGH EAST KENTUCKY WITH LOCALLY DENSE PATCHES IN THE VALLEYS. HIGH DEWPOINTS IN THE UPPER 60S AND LOWER 70S ARE PROVIDING A FLOOR TO THE COOLING THIS NIGHT WITH JUST A SMALL RIDGE AND VALLEY SPLIT EVIDENT WITH READINGS VARYING FROM LOWER 70S IN THE THERMAL BELT TO THE UPPER 60S IN THE LOW SPOTS. WINDS REMAIN LIGHT TO CALM THROUGH THE AREA. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM AS HEIGHTS FALL OVER THE OHIO VALLEY IN RESPONSE TO A BROAD TROUGH MOVING THROUGH THE NORTHEAST PORTION OF THE CONTINENT. THE ENERGY STREAM ASSOCIATED WITH THIS MOVES QUICKLY INTO THE SOUTHERN OHIO VALLEY TODAY...BUT THEN LINGERS OVERHEAD THROUGH THE WEEKEND WITH A BIT OF A RESURGENCE LATER SUNDAY. GIVEN THE GOOD MODEL AGREEMENT... FOR WEATHER SPECIFICS HAVE FAVORED A BLEND OF THE HRRR AND NAM12 THROUGH THE FIRST HALF OF THE SHORT TERM FOLLOWED BY A MIX OF THE NAM AND LATEST ECMWF SOLUTIONS. SENSIBLE WEATHER WILL FEATURE AREAS OF FOG...LOCALLY DENSE...BURNING OFF EARLY THIS MORNING. THIS WILL BE FOLLOWED BY THE ARRIVAL OF SHOWERS AND THUNDERSTORMS BY MID AFTERNOON FROM NORTH TO SOUTH AS A COLD FRONT PRESSES SOUTH INTO THE AREA. PWS WITH THIS CONVECTION WILL BE MODERATELY HIGH WHILE STORM MOTION STARTS TO SPEED UP AS THE DAY WEARS ON. THIS SHOULD LIMIT THE RISK FOR FLASH FLOODING WHEN COMPARED TO THE PAST SEVERAL DAYS. HOWEVER...A LOCALIZED THREAT FOR HEAVY RAIN WILL REMAIN SHOULD TRAINING DEVELOP IN ANY PARTICULARLY LOCATION. THE THUNDER IS ANTICIPATED TO FADE FROM THE CONVECTION LATER TONIGHT AS THE FRONT SINKS SOUTH OF AREA LEAVING JUST A FEW LIGHT SHOWERS TRAILING BEHIND. FOR SUNDAY...THE NEARBY FRONT MAY CAUSE A SHOWER OR TWO TO POP UP OVER FAR SOUTHEAST KENTUCKY WHILE THE BOUNDARY SLOWS IN RESPONSE TO A BUCKLE IN THE MID LEVEL FLOW AND A DEVELOPING WAVE AT THE SFC ALONG THE GEORGIA COAST. THE WARMTH AND STICKY HUMIDITY WILL LEAVE THE AREA...AT LEAST FOR A COUPLE OF DAYS...ONCE THE FRONT MOVES THROUGH MEANING THAT SUNDAY WILL BE A MUCH MORE COMFORTABLE DAY THAN TODAY AND ALSO PROVIDE A HINT OF THE FALL-LIKE WEATHER THAT COULD ARRIVE IN EARNEST LATER IN THE WEEK. FOR TEMPERATURES...DEWPOINTS...AND WINDS...USED THE CONSSHORT FOR THE FIRST 24 HOURS AND THEN THE SUPERBLEND THROUGH SUNDAY. DID MAKE SOME MINOR ADJUSTMENTS FOR TERRAIN DIFFERENCES WITH TEMPS TONIGHT. AS FOR POPS ENDED UP ON THE HIGH SIDE OF MOS GUIDANCE TODAY...COUNTING ON MOST OF THE AREA MEASURING AS THIS FRONT MOVES THROUGH GIVEN THE FAIRLY HIGH MOISTURE CONTENT IN PLACE. WAS SIMILAR TO THE GUIDANCE TONIGHT AND SUNDAY...LIMITING THE CHANCE POPS TO THE FAR SOUTHEAST. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 335 AM EDT SAT SEP 6 2014 THE MODELS CONTINUE TO BE IN GOOD AGREEMENT IN REGARDS TO A SIGNIFICANT PATTERN CHANGE FOR THE END OF NEXT WEEK...WITH A MAJOR COOL DOWN IN STORE. HOWEVER...THE MODELS DIFFER IN HOW THEY HANDLE THE EVOLUTION OF WEATHER SYSTEMS THAT WILL BRING SHOWERS AND STORMS TO EASTERN KENTUCKY DURING THE UPCOMING WORK WEEK. THE PERIOD WILL START OUT WARM AND DRY AS HIGH PRESSURE SUNDAY NIGHT THROUGH TUESDAY. THERE IS A POSSIBILITY OF SCATTERED SHOWERS AND STORMS FORMING BENEATH THE RIDGE ON MONDAY...AS MOISTURE OFF THE GULF OF MEXICO GETS DRAWN INTO THE AREA BY A WEAK AREA OF LOW PRESSURE THAT IS PROGGED TO PASS ACROSS THE TENNESSEE VALLEY. THE ECMWF WAS SLOWER AND WETTER THAN THE GFS FROM WEDNESDAY ONWARD. BOTH MODELS HAVE A COLD FRONT MOVING ACROSS THE OHIO AND TENNESSEE VALLEY REGIONS WEDNESDAY THROUGH FRIDAY...WITH SCATTERED SHOWERS AND STORMS FORMING IN THE VICINITY OF THE BOUNDARY. WITH UNCERTAINTY BETWEEN THE MODELS...DECIDED TO USE A BLEND OF THE ECMWF AND GFS MODELS...WITH A SLIGHT BIAS TOWARD TO NORMALLY MORE RELIABLE ECMWF SOLUTION. THE BEST CHANCES FOR RAIN WILL COME FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY EVENING DURING FRONTAL PASSAGE. TEMPERATURES THE FIRST FEW DAYS OF THE PERIOD LOOK TO BE AT OR SLIGHT BELOW NORMAL...DUE TO THE INFLUENCE OF NORTHERLY FLOW...CLOUD COVER...AND PRECIPITATION ASSOCIATED WITH AN AREA OF LOW PRESSURE THAT IS EXPECTED TO PASS THROUGH THE TENNESSEE VALLEY ON MONDAY. HIGHS ON MONDAY ARE EXPECTED TO TOP OUT AROUND 80...WITH READINGS MAXING OUT IN THE LOW TO MID 80S ON TUESDAY AND WEDNESDAY. THE BIG PATTERN CHANGE LOOKS LIKE IT WILL TAKE PLACE FROM THURSDAY ONWARD...AS A COOL CANADIAN AIR MASS SETTLES OVER THE REGION BEHIND A DEPARTING AND VERY POTENT COLD FRONT. HIGHS ON FRIDAY MIGHT ONLY TOP OUT IN THE LOW TO MID 70S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 755 AM EDT SAT SEP 6 2014 THE FOG AT THE TAF SITES WILL LIFT AND DISSIPATING BY 1330Z. BEST CHANCES OF CONVECTION SHOULD HOLD OFF UNTIL AT LEAST 15Z ACROSS THE OFFICIAL TAF SITES TODAY...AWAITING THE NEARING APPROACH OF THE COLD FRONT. WITH THE HIGH PROBABILITIES OF CONVECTION ALONG THE FRONT...WENT WITH PREVAILING TSRA AND WITH THE LOWER...MVFR... VIS/CIGS STARTING AT 15Z AT THE FARTHEST NW SITE /KSYM/...AND 17Z AT THE SOUTHERN MOST SITE /KSME/ TO MATCH UP WITH ONGOING LIKELY TO CATEGORICAL POPS IN THE FORECAST. JUST SOME SCATTERED SHOWERS FOLLOW LATER THIS EVENING AT THE SITES WITH CIGS EXPECTED TO REMAIN IN THE MVFR RANGE POST-FRONTAL. WINDS THROUGH THE BULK OF THE PERIOD WILL BE LIGHT AND VARIABLE BUT SWITCH TO THE NORTH AND NORTHWEST AT 5 TO 10 KTS BEHIND THE FRONT AS IT DROPS SOUTH DURING THE DAY. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SBH SHORT TERM...GREIF LONG TERM...AR AVIATION...GREIF
AREA FORECAST DISCUSSION...UPDATED
NWS JACKSON KY
755 AM EDT SAT SEP 6 2014 .UPDATE... ISSUED AT 730 AM EDT SAT SEP 6 2014 DID A QUICK UPDATE TO THE GRIDS TO REFLECT THE CURRENT RADAR OBSERVATIONS AND TRENDS WITH RESPECT TO POPS AND WX. THE LATEST HRRR DOESN/T REALLY GET THINGS GOING AROUND HERE UNTIL AFTER 18Z SO HAVE TRENDED TOWARD THAT IDEA. ALSO...FINE TUNED THE T/TD ONES PER THE OBS AND TRENDS. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 350 AM EDT SAT SEP 6 2014 07Z SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE MOVING THROUGH EASTERN CANADA WITH A TRAILING COLD FRONT RUNNING SOUTHWEST THROUGH THE OHIO VALLEY AND INTO SOUTHERN MISSOURI. THE REMAINS OF A SQUALL LINE HAS SETTLED JUST SOUTH OF THE OHIO RIVER...OUT AHEAD OF THE COLD FRONT. A FEW LINGERING SHOWERS REMAIN WITH THIS AS IT CONTINUES TO FADE OUT WITH ITS APPROACH TO THE JKL CWA. ON SATELLITE...MID AND HIGH LEVEL CLOUDS COVER THE OHIO VALLEY NORTH AND WEST OF THIS OUTFLOW BOUNDARY. HOWEVER...THE CLEARER SKIES TO THE SOUTH HAS ALLOWED AREAS OF FOG TO DEVELOP THROUGH EAST KENTUCKY WITH LOCALLY DENSE PATCHES IN THE VALLEYS. HIGH DEWPOINTS IN THE UPPER 60S AND LOWER 70S ARE PROVIDING A FLOOR TO THE COOLING THIS NIGHT WITH JUST A SMALL RIDGE AND VALLEY SPLIT EVIDENT WITH READINGS VARYING FROM LOWER 70S IN THE THERMAL BELT TO THE UPPER 60S IN THE LOW SPOTS. WINDS REMAIN LIGHT TO CALM THROUGH THE AREA. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM AS HEIGHTS FALL OVER THE OHIO VALLEY IN RESPONSE TO A BROAD TROUGH MOVING THROUGH THE NORTHEAST PORTION OF THE CONTINENT. THE ENERGY STREAM ASSOCIATED WITH THIS MOVES QUICKLY INTO THE SOUTHERN OHIO VALLEY TODAY...BUT THEN LINGERS OVERHEAD THROUGH THE WEEKEND WITH A BIT OF A RESURGENCE LATER SUNDAY. GIVEN THE GOOD MODEL AGREEMENT... FOR WEATHER SPECIFICS HAVE FAVORED A BLEND OF THE HRRR AND NAM12 THROUGH THE FIRST HALF OF THE SHORT TERM FOLLOWED BY A MIX OF THE NAM AND LATEST ECMWF SOLUTIONS. SENSIBLE WEATHER WILL FEATURE AREAS OF FOG...LOCALLY DENSE...BURNING OFF EARLY THIS MORNING. THIS WILL BE FOLLOWED BY THE ARRIVAL OF SHOWERS AND THUNDERSTORMS BY MID AFTERNOON FROM NORTH TO SOUTH AS A COLD FRONT PRESSES SOUTH INTO THE AREA. PWS WITH THIS CONVECTION WILL BE MODERATELY HIGH WHILE STORM MOTION STARTS TO SPEED UP AS THE DAY WEARS ON. THIS SHOULD LIMIT THE RISK FOR FLASH FLOODING WHEN COMPARED TO THE PAST SEVERAL DAYS. HOWEVER...A LOCALIZED THREAT FOR HEAVY RAIN WILL REMAIN SHOULD TRAINING DEVELOP IN ANY PARTICULARLY LOCATION. THE THUNDER IS ANTICIPATED TO FADE FROM THE CONVECTION LATER TONIGHT AS THE FRONT SINKS SOUTH OF AREA LEAVING JUST A FEW LIGHT SHOWERS TRAILING BEHIND. FOR SUNDAY...THE NEARBY FRONT MAY CAUSE A SHOWER OR TWO TO POP UP OVER FAR SOUTHEAST KENTUCKY WHILE THE BOUNDARY SLOWS IN RESPONSE TO A BUCKLE IN THE MID LEVEL FLOW AND A DEVELOPING WAVE AT THE SFC ALONG THE GEORGIA COAST. THE WARMTH AND STICKY HUMIDITY WILL LEAVE THE AREA...AT LEAST FOR A COUPLE OF DAYS...ONCE THE FRONT MOVES THROUGH MEANING THAT SUNDAY WILL BE A MUCH MORE COMFORTABLE DAY THAN TODAY AND ALSO PROVIDE A HINT OF THE FALL-LIKE WEATHER THAT COULD ARRIVE IN EARNEST LATER IN THE WEEK. FOR TEMPERATURES...DEWPOINTS...AND WINDS...USED THE CONSSHORT FOR THE FIRST 24 HOURS AND THEN THE SUPERBLEND THROUGH SUNDAY. DID MAKE SOME MINOR ADJUSTMENTS FOR TERRAIN DIFFERENCES WITH TEMPS TONIGHT. AS FOR POPS ENDED UP ON THE HIGH SIDE OF MOS GUIDANCE TODAY...COUNTING ON MOST OF THE AREA MEASURING AS THIS FRONT MOVES THROUGH GIVEN THE FAIRLY HIGH MOISTURE CONTENT IN PLACE. WAS SIMILAR TO THE GUIDANCE TONIGHT AND SUNDAY...LIMITING THE CHANCE POPS TO THE FAR SOUTHEAST. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 335 AM EDT SAT SEP 6 2014 THE MODELS CONTINUE TO BE IN GOOD AGREEMENT IN REGARDS TO A SIGNIFICANT PATTERN CHANGE FOR THE END OF NEXT WEEK...WITH A MAJOR COOL DOWN IN STORE. HOWEVER...THE MODELS DIFFER IN HOW THEY HANDLE THE EVOLUTION OF WEATHER SYSTEMS THAT WILL BRING SHOWERS AND STORMS TO EASTERN KENTUCKY DURING THE UPCOMING WORK WEEK. THE PERIOD WILL START OUT WARM AND DRY AS HIGH PRESSURE SUNDAY NIGHT THROUGH TUESDAY. THERE IS A POSSIBILITY OF SCATTERED SHOWERS AND STORMS FORMING BENEATH THE RIDGE ON MONDAY...AS MOISTURE OFF THE GULF OF MEXICO GETS DRAWN INTO THE AREA BY A WEAK AREA OF LOW PRESSURE THAT IS PROGGED TO PASS ACROSS THE TENNESSEE VALLEY. THE ECMWF WAS SLOWER AND WETTER THAN THE GFS FROM WEDNESDAY ONWARD. BOTH MODELS HAVE A COLD FRONT MOVING ACROSS THE OHIO AND TENNESSEE VALLEY REGIONS WEDNESDAY THROUGH FRIDAY...WITH SCATTERED SHOWERS AND STORMS FORMING IN THE VICINITY OF THE BOUNDARY. WITH UNCERTAINTY BETWEEN THE MODELS...DECIDED TO USE A BLEND OF THE ECMWF AND GFS MODELS...WITH A SLIGHT BIAS TOWARD TO NORMALLY MORE RELIABLE ECMWF SOLUTION. THE BEST CHANCES FOR RAIN WILL COME FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY EVENING DURING FRONTAL PASSAGE. TEMPERATURES THE FIRST FEW DAYS OF THE PERIOD LOOK TO BE AT OR SLIGHT BELOW NORMAL...DUE TO THE INFLUENCE OF NORTHERLY FLOW...CLOUD COVER...AND PRECIPITATION ASSOCIATED WITH AN AREA OF LOW PRESSURE THAT IS EXPECTED TO PASS THROUGH THE TENNESSEE VALLEY ON MONDAY. HIGHS ON MONDAY ARE EXPECTED TO TOP OUT AROUND 80...WITH READINGS MAXING OUT IN THE LOW TO MID 80S ON TUESDAY AND WEDNESDAY. THE BIG PATTERN CHANGE LOOKS LIKE IT WILL TAKE PLACE FROM THURSDAY ONWARD...AS A COOL CANADIAN AIR MASS SETTLES OVER THE REGION BEHIND A DEPARTING AND VERY POTENT COLD FRONT. HIGHS ON FRIDAY MIGHT ONLY TOP OUT IN THE LOW TO MID 70S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 755 AM EDT SAT SEP 6 2014 THE FOG AT THE TAF SITES WILL LIFT AND DISSIPATING BY 1330Z. BEST CHANCES OF CONVECTION SHOULD HOLD OFF UNTIL AT LEAST 15Z ACROSS THE OFFICIAL TAF SITES TODAY...AWAITING THE NEARING APPROACH OF THE COLD FRONT. WITH THE HIGH PROBABILITIES OF CONVECTION ALONG THE FRONT...WENT WITH PREVAILING TSRA AND WITH THE LOWER...MVFR... VIS/CIGS STARTING AT 15Z AT THE FARTHEST NW SITE /KSYM/...AND 17Z AT THE SOUTHERN MOST SITE /KSME/ TO MATCH UP WITH ONGOING LIKELY TO CATEGORICAL POPS IN THE FORECAST. JUST SOME SCATTERED SHOWERS FOLLOW LATER THIS EVENING AT THE SITES WITH CIGS EXPECTED TO REMAIN IN THE MVFR RANGE POST-FRONTAL. WINDS THROUGH THE BULK OF THE PERIOD WILL BE LIGHT AND VARIABLE BUT SWITCH TO THE NORTH AND NORTHWEST AT 5 TO 10 KTS BEHIND THE FRONT AS IT DROPS SOUTH DURING THE DAY. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GREIF LONG TERM...AR AVIATION...GREIF
AREA FORECAST DISCUSSION
NWS PADUCAH KY
625 AM CDT Sat Sep 6 2014 .SHORT TERM...(Today through Monday night) Issued at 258 AM CDT SAT SEP 6 2014 With the first 12 to 18 hours of the short term forecast period, it becomes quite nebulous to depict the coverage of mainly post frontal precipitation across the WFO PAH forecast area. All the 3km HRRR guidance pinpoints the more significant storm scale convection prior to 15z, there is some discontinuity in coverage of precipitation in the medium scale numerical model guidance. Utilized a "Superblend" of numerical model guidance to modify and mitigate various model biases during the first 12-18 hours of Weather and PoP. The current shortwave moving across Southeast Kansas should bring the last gasp of convective activity across the WFO PAH forecast area later this morning/early this afternoon. Most of the convection early this afternoon should be waning over parts of West Kentucky. After this afternoon, dry conditions should dominate through most of Monday. .LONG TERM...(Tuesday through Friday) Issued at 258 AM CDT SAT SEP 6 2014 Model blend for the extended package. A blend of previous ECMWF deterministic runs coupled with 00z/12z GFS operational runs and the GEFS 00z run. The 18z GFS was discounted as was the 00z ECMWF mainly for Thursday night on. Backed off inherited PoPs for convection Tuesday through Tuesday night. Best moisture sets up north and west of the region. No surface focus and little support aloft to warrant much activity. Have no PoPs in Tuesday, and small chances Tuesday night mainly north of a Greenville, MO to Owensboro, KY line. Warm sector much of Wednesday as well. Strong surface low should reach either WI or the Great Lakes region with a trailing front to the SW, that will approach our area from the NW by the end of the day. Have best chance PoPs for convection up toward I-64 tapering off to 30s in west KY, parts of SEMO. Will probably be a sharper gradient. Our highest PoPs will be Wednesday night. Model cluster brings the front through Wednesday night with decent columnar moisture and mid level support in WSW flow around h5. Thursday the front should gradually push on through. Will have high chance PoPs across the south tapering off to slight chances up along I-64, especially morning, tapering off more in the afternoon. Went dry Thursday night. Could be some showers close to the AR/TN state lines, some of which could creep up north into our area. The 00z ECMWF is a significant outlier in spreading substantial moisture and QPF back across the region Thursday night. Given its prior 3 runs, and 4 runs of the GFS suggesting otherwise, threw this latest depiction out. Will monitor though, in case there`s a signal suggesting a slight northward adjustment will eventually be needed. Dry Friday through Friday night with strong high pressure continuing to build in from the NW. The cool down will be noticeable behind the front Thursday through Friday. We did not go quite as cool as raw model output. That means we raised previous highs just a bit. MOS tend to be climo bias that far out. But given the we should see some mid Sept. sun, a compromise seems best. && .AVIATION... Issued at 624 AM CDT SAT SEP 6 2014 Introduced post-frontal LIFR to MVFR stratus deck into the WFO PAH TAF sites near the beginning of the forecast period, followed by a gradual rise to MVFR/VFR ceilings throughout the first 12 hours of the forecast, as drier air moves into the area from the north. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...NONE. MO...NONE. IN...NONE. KY...NONE. && $$ SHORT TERM...Smith LONG TERM...CN AVIATION...Smith
AREA FORECAST DISCUSSION
NWS CARIBOU ME
1020 AM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL REACH NORTHERN MAINE THIS MORNING THEN MOVE ACROSS THE DOWNEAST REGION LATE THIS AFTERNOON. COOLER HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT SUNDAY INTO MONDAY.&& .NEAR TERM /THROUGH TONIGHT/... 1015 AM UPDATE: WE INCREASED POPS TO BETTER MATCH FCST QPF WITH XPCTD SHWRS AND TSTMS ACROSS THE AREA FOR THE REST OF TDY. WE ALSO TRIED TO MATCH THE TMG OF STRONGER TSTMS WITH THE CURRENT PSN OF THE COLD FRONT WHICH IS NEARLY AT KCAR ATTM. THIS MEANS THAT THE POTENTIAL OF ANY STRONG STORMS ACROSS THE FAR N HAS DIMINISHED WITH THIS PTN ALREADY BEHIND THE COLD FRONT. OTHERWISE...FCST HRLY CLD CVR...TEMPS AND FCST HI TEMPS WERE MODIFIED BASED ON LATEST OBSVD TRENDS...WITH TEMPS JUST AHEAD OF THE COLD FRONT ACROSS NE PTNS OF ME ALREADY EXCEEDING PRIOR FCST HI TEMPS. TEMPS OVR THE NE...HOWEVER...WILL LIKELY FALL SHORTLY ONCE THE FRONT CROSSES THE REGION. ORGNL DISC: SEVERE WEATHER STILL LOOKS TO BE A GOOD THREAT MAINLY FROM THE HOULTON-MILLINOCKET REGION DOWN THROUGH THE CENTRAL HIGHLANDS AND INTERIOR DOWNEAST. THE LATEST SURFACE ANALYSIS AT 06Z SHOWED THE COLD FRONT MOVING INTO QUEBEC W/AN AREA OF SHOWERS AND ISOLD TSTMS MOVING ACROSS NW MAINE TOWARD NE MAINE. LATEST MESO ANALYSIS SHOWED THE BEST INSTABILITY RESIDING IN THIS REGION AS SHOWN BY THE LIFTED INDEX OF -2 TO -4 RUNNING FROM QUEBEC THROUGH NW MAINE. FURTHER E, ATMOSPHERE IS MORE STABLE ATTM. THE HRRR 3KM AND THE NAM12 WERE DOING WELL W/PLACEMENT AND INSTABILITY. A LARGE LINE OF LIGHTNING STRIKES HAD EXTENDED FROM QUEBEC DOWN ACROSS NYS AND PA BUT HAVE SINCE DISSIPATED. THIS IS EXPECTED TO CHANGE LATER THIS MORNING INTO THE AFTERNOON THE FRONT CONTINUE TO PUSH E AND THE AIRMASS DESTABILIZES. THE LATEST RUNS OF THE NAM AND GFS CONTINUE TO SHOW THE HIGHEST THREAT FOR POSSIBLY SEVERE TSTMS W/EHI RUNNING FROM 1 TO 2 AND SB/MU CAPES OF 1200-2000 JOULES AND 0-6KM SHEAR OF 35-40 KTS. ANOTHER FACTOR TO CONSIDER WILL BE THE DIRECTIONAL SHEAR THROUGH 850MBS AND LCLS MAKING THEIR DECENT FROM 5K FT DOWN TO 2500 FT. IN ADDITION TO ALL THIS WILL BE VERY HIGH PWATS OF 1.7+ INCHES AND SWEAT INDEX OF 300+. ALL THIS WOULD SUGGEST THE POTENTIAL FOR DAMAGING WINDS AND VERY HEAVY RAINFALL. SOME ROTATION COULD BE SEEN IN THE STRONGER STORMS GIVEN THE TURNING IN THE LLVLS AND THE LOWER LCLS. KEPT THE ENHANCED WORDING FOR GUSTY WINDS AND HEAVY RAINFALL. THE WORDING MIGHT NEED TO BE BOOSTED TO INCLUDE DAMAGING WINDS IF THINGS HOLD W/THE UPDATE LATER THIS MORNING. TEMPERATURES WILL FALL BACK ACROSS NORTHERN MAINE AFTER 1 PM AS THE FRONT SLIDE THROUGH WHILE THE CENTRAL HIGHLANDS AND DOWNEAST WILL HAVE TIME TO HEAT UP W/AFTERNOON TEMPERATURES HITTING IN THE LOWER 80S. SPC HAS KEPT THE SLIGHT RISK FOR SEVERE WEATHER FOR OUR REGION IN PLACE FOR TODAY. THE COLD FRONT IS FORECAST TO SLIDE INTO THE COASTAL WATERS THIS EVENING W/PARTIAL CLEARING TAKING PLACE AND A DRAMATIC COOL DOWN. WE ARE TALKING 10-15 DEGREES COOLER THAN WHAT WE HAVE SEEN THAT LAST FEW MORNINGS. SOME OF THE SITES BACK TO THE W AND NW COULD DROP BACK INTO THE UPPER 30S BY EARLY MONDAY MORNING. && .SHORT TERM /SUNDAY THROUGH MONDAY/... AT THE START OF THE NEAR TERM PERIOD. A COLD FRONT WILL BE EXTENDED ALONG THE COAST OF MAINE. HIGHER PRESSURE WILL BEGIN TO BUILD INTO THE AREA. COOLER DRIER AIR WILL MOVE INTO THE AREA WITH THE HIGH. DAY TIME TEMPS SUNDAY IN THE MID 60S AND LOWER 60S MONDAY. OVERNIGHT LOWS IN THE LOWER 40S. THE HIGH PRESSURE RIDGE WILL DOMINATE THE WEATHER THROUGH THE NEAR TERM PERIOD OF THE FORECAST. LOADED A BLEND OF THE GFS/NAM/GEM/ECMWF FOR HRLY TEMPS/DP...WND...POP... AND SKY. NAWAVE 4 FOR SEAS IN THE COASTAL WATERS. ADDED 15 PERCENT TO WINDS FOR GUSTS OVER LAND...25 PERCENT OVER COASTAL WATERS. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A HIGH PRESSURE RIDGE WILL BE IN PLACE OVER THE AREA AT THE START OF THE LONG TERM. A LOW PRESSURE SYSTEM MOVING UP THE EAST COAST AT THE START OF THE PERIOD THE GFS PLACES IT ALONG THE GULF STREAM EAST OF NJ...THE ECMWF ALONG THE COAST OF VA. AND THE GEM PLACES IT EAST OF CAPE COD...SOUTH OF SW NOVA SCOTIA. BY WED MRNG THE GFS MOVES THE LOW NORTH TO JUST SOUTH OF CAPE COD...WITH THE PRECIP SHIELD EXTENDING INTO DOWNEAST MAINE...THE ECMWF MOVES THE LOW TO DELMARVA...KEEPS THE PCPN SHIELD SOUTH OF CAPE COD. THE GEM MOVES THE LOW TO A POSITION SOUTH OF CENTRAL NOVA SCOTIA WELL EAST OF OUR AREA. A NEW LOW OVER THE CENTRAL MIDWEST WITH A COLD FRONT THAT EXTENDS FROM NORTHERN QUEBEC SW TO THE CENTRAL GREAT LAKES REGION. THE LOW WILL MOVE EAST AND BY THUR MRNG THE GFS MOVE IT TO THE ERN GREAT LAKES REGION...WITH ITS WARM FRONT EXTENDING INTO NRN MAINE. THE ECMWF IS A BIT SLOWER WITH THE FORWARD MVMNT OF THIS LOW...MOVING IT TO LAKE HURON. BY THURS EVNG...THE ECMWF CATCHES UP A BIT. THE GFS MOVES THE LOW TO SRN QUEBEC/WRN MAINE. THE ECMWF MOVES THE LOW TO SW QUEBEC. FROM THURS EVNG THROUGH THE END OF THE PERIOD. THE GFS AND ECMWF ARE ABOUT ONE PERIOD OUT OF FAZE WITH THE GFS BEING THE FASTER OF THE TWO MODELS. UNSETTLED WEATHER WILL PERSIST FROM THURS EVNG THROUGH THE END OF THE PERIOD AS AN UPPER LOW SLOWLY FILLS OVER WEST CENTRAL QUEBEC SE OF JAMES BAY. LOADED THE SUPERBLEND FOR THE EXTENDED PERIOD OF THE FORECAST. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... NEAR TERM: IFR SETTING UP ACROSS KBHB AND POSSIBLY KBGR THIS MORNING WHILE THE NORTHERN TERMINALS WILL SEE VFR THIS MORNING GOING TO MVFR. MVFR CONDITIONS FOR ALL TERMINALS INTO THE AFTERNOON. VFR EXPECTED ACROSS THE NORTHERN TERMINALS TONIGHT WHILE KBGR AND KBHB COULD SEE A BRIEF PERIOD OF IFR BEFORE CLEARING LATER TONIGHT AS THE FRONT CLEARS THE AREA. SHORT TERM: A FEW STRAY SHOWERS FOR BGR AND BHB EARLY IN THE PERIOD...OTHERWISE VFR CONDITIONS ALL SITES. && .MARINE... NEAR TERM: 1015 AM ...MAX WIND GUSTS WERE REDUCED TO 20 KT FOR THE REMAINDER OF THE DAY...DUE TO VERY STABLE SFC-500M LAPSE RATES. OTHERWISE...CURRENT SCA OVR THE OUTER MZS REMAIN IN PLACE. ORGNL DISC...CONDITIONS ATTM BELOW SCA LEVELS BOTH IN THE WINDS AND SEAS W/15 KTS AND 4 TO 5 FT. SEAS WILL CONT AT SCA LEVELS THRU THE AFTERNOON WINDS DROP OFF BEHIND THE FRONT TO LESS THAN 15 KTS AND SEAS WILL COME DOWN AS THE WIND GOES OFFSHORE. SHORT TERM: WINDS AND SEAS BELOW SCA CRITERIA THROUGH THE PERIOD. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ050- 051. && $$ NEAR TERM...VJN SHORT TERM...NORTON LONG TERM...NORTON AVIATION...VJN/NORTON MARINE...VJN/NORTON
AREA FORECAST DISCUSSION
NWS GRAY ME
943 AM EDT SAT SEP 6 2014 .SYNOPSIS... THE RETURN FLOW AROUND HIGH PRESSURE HAS INTRODUCED A VERY WARM AND HUMID AIR MASS TO THE REGION. A COLD FRONT WILL CROSS THE REGION TODAY ACCOMPANIED BY SHOWERS AND THUNDERSTORMS. SOME THUNDERSTORMS MAY PRODUCE STRONG GUSTY WINDS...FREQUENT LIGHTNING...AND TORRENTIAL DOWNPOURS WITH LOCALIZED FLOODING. HIGH PRESSURE AND DRY AIR FOLLOWS THE FRONT SUNDAY THROUGH TUESDAY. THE NEXT DISTURBANCE WITH UNSETTLED WEATHER SHOULD ARRIVE BY THE MIDDLE OF NEXT WEEK. THE UNSETTLED WEATHER IS EXPECTED TO CONTINUE THROUGH THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE... HAVE UPDATED THE GRIDS BASED ON CURRENT CONDITIONS AS WELL AS LATEST MESOSCALE MODEL DATA. LATEST HRRR CONTINUES TO SHOW THE HIGHEST DEW POINTS AND THE GREATEST CHANCE FOR SEVERE WEATHER TO BE OVER SOUTHERN NEW HAMPSHIRE AND SOUTHWEST MAINE. WE CURRENTLY REMAIN IN A SLIGHT RISK FOR SEVERE WEATHER TODAY. WILL CONTINUE THE ENHANCED WORDING...WITH THE PRIMARY THREAT BEING DAMAGING WIND GUSTS IN SEVERE STORMS. AN ISOLATED TORNADO IS POSSIBLE AS WELL...WITH STRONG WIND FIELDS AND SIGNIFICANT SHEAR. HAVE ADJUSTED DEW POINT AND CLOUD GRIDS AS WELL BASED ON CURRENT SATELLITE IMAGERY...SURFACE OBSERVATIONS AND SOUNDING ANALYSIS. KEY WILL BE IF DRY AIR MIXES DOWN FROM ABOVE AND LOWERS OUR DEW POINTS OR NOT. MOST LIKELY AREA TO HAVE DEW POINTS NEAR 70 DEGREES WILL BE SOUTHERN NEW HAMPSHIRE AND YORK COUNTY IN MAINE. PREV DISC... HAVE UPDATED THE FORECAST SLIGHTLY THIS MORNING TO INCORPORATE LATEST TRENDS IN OBSERVATIONAL DATA. SHOULD SEE PLENTY OF SUN THIS MORNING WHICH SHOULD LEAD TO QUICK INSOLATIONAL HEATING. FORECAST FOR THUNDERSTORMS REMAINS THE SAME FOR THIS AFTERNOON. PREVIOUSLY... A WARM AND HUMID AIR MASS HAS OVERSPREAD THE REGION AS OF EARLY THIS SATURDAY MORNING...AS EVIDENCED BY TEMPERATURES STILL IN THE 70S WITH DEWPOINTS WELL INTO THE 60S AS OF 3 AM. A COLD FRONT IS EXPECTED TO CROSS THE AREA TODAY AND THIS SHOULD AID IN THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS. THE MAIN CONCERN REVOLVES AROUND STORM COVERAGE...TIMING...AND SEVERITY. AS A SHORT WAVE TROUGH APPROACHES FROM THE NW AND CONTINUES TO INDUCE HEIGHT FALLS...A COLD FRONT AND ASSOCIATED SFC CONVERGENCE SHOULD INITIATE THUNDERSTORMS ACROSS THE INTERIOR AROUND MIDDAY. STRONG SFC HEATING IS EXPECTED OUT AHEAD OF THE THUNDERSTORM ACTIVITY WITH HIGHS IN THE MID TO UPPER 80S PROGGED ON THE COASTAL PLAIN. A FEW LOCATIONS MAY EVEN TOUCH 90 FROM INTERIOR ROCKINGHAM COUNTY NORTHWARD INTO INTERIOR YORK AND CUMBERLAND COUNTIES. THIS COMBINED WITH DEWPOINT VALUES IN THE UPPER 60S TO AROUND 70 SHOULD RESULT IN MODERATE SBCAPE BY EARLY AFTERNOON WITH VALUES IN EXCESS OF 2000 J/KG. THEREFORE...PLENTY OF INSTABILITY IS EXPECTED TO BE PRESENT TO SUPPORT SVR STORMS. HOWEVER... THERE ARE SOME NEGATIVES...SUCH AS GRADUALLY WEAKENING MID LEVEL LAPSE RATES AS THE DAY PROGRESSES. ALSO...THE BEST DEEP LAYER SHEAR AND UPPER SUPPORT IS EXPECTED TO LAG BEHIND THE COLD FRONT. IN ADDITION...GOOD MIXING TO AROUND 850 MB IS EXPECTED TODAY. THIS WILL PROBABLY RESULT IN FALLING DEWPOINTS THIS AFTERNOON IN SOME AREAS...AND THIS WOULD EAT AWAY AT CAPE VALUES. ANOTHER ISSUE MAY BE THAT A PREFRONTAL TROF THAT IS EXPECTED TO DEVELOP ON THE COASTAL PLAIN EARLY THIS AFTERNOON COULD MOVE OFFSHORE TOO EARLY. THIS WOULD LOWER DEWPOINTS ACROSS THE AREA AND WEAKEN SFC CONVERGENCE. NEVERTHELESS...WE EXPECT AT LEAST A COUPLE OF SEVERE STORMS IN THE FORM OF ORGANIZED MULTICELL CLUSTERS AND LINE SEGMENTS WHICH MAY EVENTUALLY FORM A MORE SOLID LINE OF STORMS AS THEY APPROACH THE COAST. THE MAIN THREAT LOOK TO BE DAMAGING WINDS. TORRENTIAL DOWNPOURS ARE EXPECTED IN STORMS WITH THE ATTENDANT LOW RISK OF ISOLD FLASH FLOODING IN AREAS WHERE STORMS TRAIN IN THE HIGH PWAT AIR MASS. A NON-ZERO TORNADO THREAT MAY EXIST TODAY IN THE VICINITY OF MESOSCALE BOUNDARIES IF BRIEF SUPERCELL STRUCTURES CAN DEVELOP. AREAS OF LOCALLY BACKED WINDS TODAY WOULD BE SUPPORTIVE OF FAIRLY SIZABLE LOW LEVEL HODOGRAPHS GIVEN THE RELATIVELY STRONG SWLY WINDS EXPECTED IN THE 0-2 KM LAYER. THIS IS CONDITIONAL APON FAVRORABLE MOISTURE PROFILES THIS AFTERNOON...IE...IF WE DON/T MIX OUT THE RICH LOW LEVEL MOISTURE DUE TO MIXING OR A DEPARTING PREFRONTAL TROF TOO EARLY. CAPPED POPS AT LIKELY TODAY BECAUSE I/M NOT SO SURE THAT EVERYONE WILL SEE A STORM. THE MODELS SEEMED TO HAVE BACKED OFF ON COVERAGE A LITTLE BIT...PROBABLY DUE TO THE NEGATIVE FACTORS OUTLINED ABOVE. HIGHEST POPS HAVE BEEN PLACED BETWEEN 19Z AND 23Z. SFC WINDS LOOK TO BECOME GUSTY TODAY OUTSIDE OF ANY CONVECTION...POSSIBLY TO AROUND 25 MPH. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... SHOWERS AND STORMS WILL SWEEP OFFSHORE EARLY THIS EVENING. CLEARING SHOULD OCCUR TONIGHT ASIDE FROM LEFTOVER STRATUS AND FOG. SUNDAY SHOULD BE A REALLY NICE DAY...WARM AND MUCH DRIER. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... MODELS ARE IN A LITTLE BETTER AGREEMENT THIS MORNING FOR THE LONG TERM PERIOD. HIGH PRESSURE WILL DOMINATE THE WEATHER FOR SUNDAY NIGHT THROUGH TUESDAY. TEMPERATURES SUNDAY NIGHT WILL DIP TO RATHER CHILLY LEVELS WITH SOME OF THE COLDER MOUNTAIN VALLEYS POSSIBLY SEEING SOME FROST. A WEAK SYSTEM WILL PASS SOUTH OF THE REGION TUESDAY AND TUESDAY NIGHT AND SPREAD CLOUDS INTO SOUTHERN AREAS WITH ONLY A SLIGHT CHANCE OF A SHOWER. FAIR WEATHER IS EXPECTED WEDNESDAY WITH THE WEAK SURFACE RIDGE REMAINING ACROSS THE REGION. LOW PRESSURE MOVING THROUGH SOUTHEASTERN CANADA THURSDAY AND THURSDAY NIGHT WILL DRAG A COLD FRONT ACROSS THE REGION WITH SHOWERS/TSTMS LIKELY DURING THE DAY. MODELS START TO DIVERGE A BIT WITH THIS SYSTEM...ADDING UNCERTAINTY TO THE FORECAST. THE FRONT SHOULD BE OFF THE COAST BY FRIDAY MORNING. A SECOND FRONT WILL APPROACH THE AREA SATURDAY WITH AN INCREASING CHANCE OF SHOWERS. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY...MAINLY THIS AFTERNOON. THIS WOULD ALLOW FOR LOCAL IFR CONDITIONS. BETTER CONDITIONS ARE FORECAST LATER TONIGHT ALTHOUGH SOME STRATUS AND FOG MAY DEVELOP IN RIVER VALLEYS AND ALONG THE COAST...ESPECIALLY THIS EVENING BEFORE DRIER AIR ARRIVES. WALL TO WALL VFR EXPECTED SUNDAY. LONG TERM...MAINLY VFR CONDITIONS WITH IFR CONDITIONS POSSIBLE IN MORNING VALLEY FOG. && .MARINE... SHORT TERM...SCA FOR THE OUTER WATERS THROUGH THIS EVENING FOR MARGINAL SMALL CRAFT CONDITIONS. A FEW 25 KT GUSTS MAY OCCUR IN THE BAYS AS WELL...BUT CONFIDENCE IS LOW. THUNDERSTORMS WITH GUSTY WINDS ARE EXPECTED TO POSE A HAZARD LATE THIS AFTERNOON. LONG TERM...NO FLAGS THROUGH TUESDAY. SEAS MAY REACH SCA CRITERIA LATE TUE NIGHT. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT SUNDAY FOR ANZ150-152-154. && $$ JC
AREA FORECAST DISCUSSION
NWS CARIBOU ME
632 AM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL REACH NORTHERN MAINE THIS MORNING THEN MOVE ACROSS THE DOWNEAST REGION LATE THIS AFTERNOON. COOLER HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT SUNDAY INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/... 630 AM UPDATE...ADJUSTED THE TIMING FOR SHOWERS AND STORMS BACK BY ABOUT 2 HOURS BASED ON THE LATEST RADAR AND SATELLITE TRENDS. THE BEST INSTABILITY STILL RESIDE BACK ACROSS QUEBEC AND ACROSS THE CROWN OF MAINE PER LATEST LIFTED INDEX(-1 TO -3). KEPT THE MENTION OF FOG IN THE FORECAST FOR A FEW MORE HOURS. INSTABILITY AXIS STARTING TO SET UP ACROSS SW MAINE NOSING TOWARD INTERIOR DOWNEAST. BANGOR TO BAR HARBOR LOOKS TO BE PRETTY STABLE DUE TO STRATUS AND FOG WHICH SHOULD LIFT AND BURN OFF AFTER 12Z. SEVERE WEATHER STILL LOOKS TO BE A GOOD THREAT MAINLY FROM THE HOULTON-MILLINOCKET REGION DOWN THROUGH THE CENTRAL HIGHLANDS AND INTERIOR DOWNEAST. THE LATEST SURFACE ANALYSIS AT 06Z SHOWED THE COLD FRONT MOVING INTO QUEBEC W/AN AREA OF SHOWERS AND ISOLD TSTMS MOVING ACROSS NW MAINE TOWARD NE MAINE. LATEST MESO ANALYSIS SHOWED THE BEST INSTABILITY RESIDING IN THIS REGION AS SHOWN BY THE LIFTED INDEX OF -2 TO -4 RUNNING FROM QUEBEC THROUGH NW MAINE. FURTHER E, ATMOSPHERE IS MORE STABLE ATTM. THE HRRR 3KM AND THE NAM12 WERE DOING WELL W/PLACEMENT AND INSTABILITY. A LARGE LINE OF LIGHTNING STRIKES HAD EXTENDED FROM QUEBEC DOWN ACROSS NYS AND PA BUT HAVE SINCE DISSIPATED. THIS IS EXPECTED TO CHANGE LATER THIS MORNING INTO THE AFTERNOON THE FRONT CONTINUE TO PUSH E AND THE AIRMASS DESTABILIZES. THE LATEST RUNS OF THE NAM AND GFS CONTINUE TO SHOW THE HIGHEST THREAT FOR POSSIBLY SEVERE TSTMS W/EHI RUNNING FROM 1 TO 2 AND SB/MU CAPES OF 1200-2000 JOULES AND 0-6KM SHEAR OF 35-40 KTS. ANOTHER FACTOR TO CONSIDER WILL BE THE DIRECTIONAL SHEAR THROUGH 850MBS AND LCLS MAKING THEIR DECENT FROM 5K FT DOWN TO 2500 FT. IN ADDITION TO ALL THIS WILL BE VERY HIGH PWATS OF 1.7+ INCHES AND SWEAT INDEX OF 300+. ALL THIS WOULD SUGGEST THE POTENTIAL FOR DAMAGING WINDS AND VERY HEAVY RAINFALL. SOME ROTATION COULD BE SEEN IN THE STRONGER STORMS GIVEN THE TURNING IN THE LLVLS AND THE LOWER LCLS. KEPT THE ENHANCED WORDING FOR GUSTY WINDS AND HEAVY RAINFALL. THE WORDING MIGHT NEED TO BE BOOSTED TO INCLUDE DAMAGING WINDS IF THINGS HOLD W/THE UPDATE LATER THIS MORNING. TEMPERATURES WILL FALL BACK ACROSS NORTHERN MAINE AFTER 1 PM AS THE FRONT SLIDE THROUGH WHILE THE CENTRAL HIGHLANDS AND DOWNEAST WILL HAVE TIME TO HEAT UP W/AFTERNOON TEMPERATURES HITTING IN THE LOWER 80S. SPC HAS KEPT THE SLIGHT RISK FOR SEVERE WEATHER FOR OUR REGION IN PLACE FOR TODAY. THE COLD FRONT IS FORECAST TO SLIDE INTO THE COASTAL WATERS THIS EVENING W/PARTIAL CLEARING TAKING PLACE AND A DRAMATIC COOLDOWN. WE ARE TALKING 10-15 DEGREES COOLER THAN WHAT WE HAVE SEEN THAT LAST FEW MORNINGS. SOME OF THE SITES BACK TO THE W AND NW COULD DROP BACK INTO THE UPPER 30S BY EARLY MONDAY MORNING. && .SHORT TERM /SUNDAY THROUGH MONDAY/... AT THE START OF THE NEAR TERM PERIOD. A COLD FRONT WILL BE EXTENDED ALONG THE COAST OF MAINE. HIGHER PRESSURE WILL BEGIN TO BUILD INTO THE AREA. COOLER DRIER AIR WILL MOVE INTO THE AREA WITH THE HIGH. DAY TIME TEMPS SUNDAY IN THE MID 60S AND LOWER 60S MONDAY. OVERNIGHT LOWS IN THE LOWER 40S. THE HIGH PRESSURE RIDGE WILL DOMINATE THE WEATHER THROUGH THE NEAR TERM PERIOD OF THE FORECAST. LOADED A BLEND OF THE GFS/NAM/GEM/ECMWF FOR HRLY TEMPS/DP...WND...POP... AND SKY. NAWAVE 4 FOR SEAS IN THE COASTAL WATERS. ADDED 15 PERCENT TO WINDS FOR GUSTS OVER LAND...25 PERCENT OVER COASTAL WATERS. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A HIGH PRESSURE RIDGE WILL BE IN PLACE OVER THE AREA AT THE START OF THE LONG TERM. A LOW PRESSURE SYSTEM MOVING UP THE EAST COAST AT THE START OF THE PERIOD THE GFS PLACES IT ALONG THE GULF STREAM EAST OF NJ...THE ECMWF ALONG THE COAST OF VA. AND THE GEM PLACES IT EAST OF CAPE COD...SOUTH OF SW NOVA SCOTIA. BY WED MRNG THE GFS MOVES THE LOW NORTH TO JUST SOUTH OF CAPE COD...WITH THE PRECIP SHIELD EXTENDING INTO DOWNEAST MAINE...THE ECMWF MOVES THE LOW TO DELMARVA...KEEPS THE PCPN SHIELD SOUTH OF CAPE COD. THE GEM MOVES THE LOW TO A POSITION SOUTH OF CENTRAL NOVA SCOTIA WELL EAST OF OUR AREA. A NEW LOW OVER THE CENTRAL MIDWEST WITH A COLD FRONT THAT EXTENDS FROM NORTHERN QUEBEC SW TO THE CENTRAL GREAT LAKES REGION. THE LOW WILL MOVE EAST AND BY THUR MRNG THE GFS MOVE IT TO THE ERN GREAT LAKES REGION...WITH ITS WARM FRONT EXTENDING INTO NRN MAINE. THE ECMWF IS A BIT SLOWER WITH THE FORWARD MVMNT OF THIS LOW...MOVING IT TO LAKE HURON. BY THURS EVNG...THE ECMWF CATCHES UP A BIT. THE GFS MOVES THE LOW TO SRN QUEBEC/WRN MAINE. THE ECMWF MOVES THE LOW TO SW QUEBEC. FROM THURS EVNG THROUGH THE END OF THE PERIOD. THE GFS AND ECMWF ARE ABOUT ONE PERIOD OUT OF FAZE WITH THE GFS BEING THE FASTER OF THE TWO MODELS. UNSETTLED WEATHER WILL PERSIST FROM THURS EVNG THROUGH THE END OF THE PERIOD AS AN UPPER LOW SLOWLY FILLS OVER WEST CENTRAL QUEBEC SE OF JAMES BAY. LOADED THE SUPERBLEND FOR THE EXTENDED PERIOD OF THE FORECAST. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... NEAR TERM: IFR SETTING UP ACROSS KBHB AND POSSIBLY KBGR THIS MORNING WHILE THE NORTHERN TERMINALS WILL SEE VFR THIS MORNING GOING TO MVFR. MVFR CONDITIONS FOR ALL TERMINALS INTO THE AFTERNOON. VFR EXPECTED ACROSS THE NORTHERN TERMINALS TONIGHT WHILE KBGR AND KBHB COULD SEE A BRIEF PERIOD OF IFR BEFORE CLEARING LATER TONIGHT AS THE FRONT CLEARS THE AREA. SHORT TERM: A FEW STRAY SHOWERS FOR BGR AND BHB EARLY IN THE PERIOD...OTHERWISE VFR CONDITIONS ALL SITES. && .MARINE... NEAR TERM: CONDITIONS ATTM BELOW SCA LEVELS BOTH IN THE WINDS AND SEAS W/15 KTS AND 4 TO 5 FT. WINDS AND SEAS ARE EXPECTED TO INCREASE TO SCA LEVELS LATER THIS MORNING INTO THE AFTERNOON AS THE LLVL JET OF 35 KTS MOVES ACROSS THE WATERS. WINDS DROP OFF BEHIND THE FRONT TO LESS THAN 15 KTS AND SEAS WILL COME DOWN AS THE WIND GOES OFFSHORE. SHORT TERM: WINDS AND SEAS BELOW SCA CRITERIA THROUGH THE PERIOD. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ050- 051. && $$ NEAR TERM...HEWITT SHORT TERM...NORTON LONG TERM...NORTON AVIATION...HEWITT/NORTON MARINE...HEWITT/NORTON
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1034 AM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL BRING SHOWERS AND THUNDERSTORMS TODAY...WITH MUCH COOLER TEMPERATURES SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... LATEST RADAR/SAT/SFC OBS INDICATE THE ANAFRONT APPROACHING FROM THE WEST JUST NORTH AND EAST OF THE FORECAST AREA DRAPED ALONG THE SOUTHERN EDGE OF LAKE ERIE AND THEN DROPPING SOUTH JUST EAST OF CINCINNATI. ASSOCIATED PRECIPITATION ALONG AND JUST BEHIND THE FRONT HAS BEEN MAINLY LIGHT SHOWERS...BUT AS THE FRONT SLOWLY TRANSITIONS EAST ISOLATED THUNDERSTORMS SHOULD DEVELOP AS WELL OVER AREAS WHERE THERE HAS BEEN SUFFICIENT SFC HEATING TO CONTRIBUTE TO INSTABILITY. THE 12Z NAM APPEARS TO HAVE TRENDED SLOWER...WHICH IS GOOD AS ALL 00Z AND 06Z RUNS LOOKED TOO FAST WITH THE PROGRESSION OF THE FRONT. THE GFS AND LOCALLY RUN HIRES WRF MODELS WHICH USE GFS BOUNDARY CONDITIONS SEEMED TO HAVE THE BEST HANDLE ON THE SITUATION AND ADJUSTMENTS TO THE FORECAST FOR TODAY WERE LARGELY BASED ON THAT ALONG WITH 12Z SOUNDING DATA...WITH LAST MINUTE TWEAKS AS THE 12Z HRRR RUN FINALLY BEGAN TO SLOW THINGS DOWN AS WELL. WITH THAT...HAVE PARED BACK THE PRECIPITATION FORECAST BY CUTTING BACK ON PREFRONTAL AND POSTFRONTAL POPS AS THERE IS BETTER CONFIDENCE IN TIMING. BY THIS EVENING THE FRONT SHOULD BE LARGELY SOUTH OF THE FORECAST AREA WITH MUCH DRIER AIR AND COOLER TEMPERATURES IN ITS WAKE. TEMPERATURES TODAY WILL BE HIGHEST SOUTH AND EAST OF PITTSBURGH NEAR 80...WITH LOWER TO MID 70S FAR NORTH. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... DRY HIGH PRESSURE WILL DOMINATE THROUGH SUNDAY NIGHT. AS HIGH SHIFTS EAST MONDAY MODELS AGREE ON LOW PRESSURE DEVELOPING ALONG THE MID ATLANTIC COAST BUT DIFFER ON PLACEMENT OF DEEPER MOISTURE. WOULD EXPECT BULK OF ANY ACTIVITY TO REMAIN EAST OF THE RIDGES AND HAVE LOW CHC TO CHC POPS MONDAY IN THE SOUTHEAST RIDGES. BY TUESDAY A SHORTWAVE WILL WORK QUICKLY EAST IN ZONAL FLOW WITH INCREASING LOW AND MID LEVEL MOISTURE. WITH A RATHER WEAK SYSTEM HAVE GONE WITH SLIGHT CHANCE POPS. TEMPERATURES WILL REBOUND TO ABOVE SEASONAL AVERAGES BY TUESDAY. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... INCRG PCPN CHCS ARE EXPD WED INTO THU AS LOW PRES ADVNS ACRS THE GT LKS AND UPR OH VLY RGN. SFC HIGH PRES WL BLD IN BY LT WK INTO THE WKEND UNDER GENL COOL NERN CONUS UPR TROFG. THE COOL UPR TROFG WL ALLOW TEMPS TO FALL FM NR SEASONAL LVLS MID WK...TO SVRL DEG BLO AVG BY LT WK INTO THE WKEND. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... GENL VFR CONDS ARE EXPD UNTIL A CDFNT ADVNS ACRS THE RGN TDA WITH MVFR CONDS IN CU/SC AND OCNL SHWRS EXPD. BEST CHC FOR AFTN TSTMS EXPD TO BE S OF PIT WITH BETTER INSTBY SO INCLUDED A TEMPO TS MENTION IN THE MGW TAF. EXP A WSHFT FM SW TO NW WITH FROPA...AND AN EVENTUAL CLRG TREND BY THIS EVE AS THE FNT FURTHER EXITS. AREAS OF MVFR FOG IS EXPD TO DVLP LT TNGT ESP WHERE CLRG TAKES PLACE AFT SUNSET. OUTLOOK.../SUNDAY THROUGH WEDNESDAY/... RSTRNS ARE PSBL WITH A MD WK LOW PRES SYSTEM. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1049 AM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL PUSH SOUTHEAST ACROSS THE STATE THIS AFTERNOON AND TONIGHT. HIGH PRESSURE OVER THE MIDWEST WILL THEN SLIDE ACROSS PENNSYLVANIA SUNDAY INTO EARLY NEXT WEEK...AS A WEAK LOW PRESSURE SYSTEM TRACKS SOUTH OF PENNSYLVANIA AND OFF THE MID ATLANTIC COAST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CLEAR SKIES EXTEND FROM FRANKLIN TO LANCASTER COUNTIES AT MID TO LATE MORNING...ENABLING SFC TEMPS TO WARM TO THE LOWER 80S AS OF 10 AM. EARLIER FOG HAS DISSIPATED. MID TO HIGH CLOUD CONVECTIVE DEBRIS FROM OVERNIGHT SQUALL LINE DISSIPATING EXTENDS FROM WV THROUGH THE LAUREL HIGHLANDS NORTHEASTWARD TO THE POCONO PLATEAU. SCT-BKN LAYERED CLOUDS EXTEND FROM THE WEST CENTRAL MOUNTAINS NORTHWARD ACROSS THE REMAINDER OF NORTH CENTRAL PA AHEAD OF THE SLOWLY APPROACHING FRONTAL ZONE...WHICH APPEARS WILL CROSS PA IN TWO DISTINCT PIECES TODAY...ACCORDING TO 4KM SPC WRF IDEA AND EXTRAPOLATING CURRENT RADAR VIEW. LATEST REGIONAL RADAR MOSAIC INDICATES AN INITIAL NARROW BAND OF SHOWERS FROM NORTHEAST OHIO THROUGH NORTHWEST PA AND INTO THE FINGERLAKES REGION OF WESTERN NY...SLOWLY PUSHING SOUTHEASTWARD. NEW HRRR AND 00Z 4KM SPC WRF TAKES THIS INITIAL BATCH OF SHOWERS ACROSS THE NORTHWEST THIRD TO HALF OF CENTRAL PA THROUGH 16-17Z...THEN DISSIPATES IT IN FAVOR OF THE FRONTAL ZONE CONVECTION WHICH AGAIN TRACKS ACROSS THE NORTHWEST MOUNTAINS FROM THE EARLY TO MID AFTERNOON HOURS AND REACHES THE CENTRAL MOUNTAINS MID TO LATE AFTERNOON. EARLIER HRRR HAS TRENDED TOWARDS 4KM SPC WRF DEPICTION...AND IS NOT LONGER DEPICTING CONVECTION POSSIBLE AT ANY TIME FROM MID TO LATE MORNING ONWARD ACROSS ALL BUT FAR SOUTHEAST PA AS THE EARLIER MORNING RUN HAD. ISOLATED ACTIVITY IS LIKELY TO SPROUT OVER THE LOWER SUSQ IN THE AREA OF MAX SFC HEATING THIS MORNING (TEMPS WHILE WRITING THIS ARE LIKELY TO WARM INTO THE MID 80S AT THE TOP OF NEXT HOUR)...BUT THINK THE MAIN ACTIVITY WILL COME WITH THE ACTUAL FRONT LATER THIS AFTERNOON AND EVENING. MODIFIED TIMING OF HIGHER CONVECTIVE POPS LATER THIS MORNING AND AFTERNOON BASED ON CURRENT RADAR ACTIVITY AND LATEST HRRR...WHICH AS MENTIONED TOWARDS THE OVERNIGHT 4KM SPC WRF TIMING. THIS DELAYS THE HIGHEST CONVECTIVE POPS ACROSS CENTRAL PA TO ~20Z OR AFTERWARDS. MORNING SHOWERS ACROSS THE NORTHWEST MOUNTAINS WILL PUSH SOUTHEAST AND TRANSITION INTO NUMEROUS +SHRA AND A FEW BKN LINES OF TSRA IN THE AFTERNOON OVR THE SERN HALF OF THE AREA. FARTHER NORTH...THE MAIN FRONTAL BAND OF CONVECTION SHOULD INTENSITY EARLY TO MID AFTERNOON OVER THE NORTHWEST MOUNTAINS AND SLIDE SOUTHEASTWARD INTO THE CENTRAL MOUNTAINS MID TO LATE AFTERNOON. AS EARLIER MENTIONED...SREF PROB FOR CAPES EXCEEDING 2000 J/KG RAMP UP QUICKLY IN THE 15-18Z TIMEFRAME ALONG AND EAST OF A LINE FROM NEAR KJST...TO KUNV AND KELM. ISOLATED SEVERE IS POSSIBLE...LATEST SPC OUTLOOK KEEPS SCHUYLKILL...NORTHUMBERLAND... MONTOUR COLUMBIA AND SULLIVAN COUNTIES IN DAY 1 SLIGHT RISK AREA. SHEAR APPEARS TO BE LACKING FOR WIDESPREAD SEVERE WEATHER...BUT SOME STORMS WILL AT LEAST BE MARGINAL WITH AN ISOLATED THREAT OF SEVERE WIND GUSTS...ESPECIALLY ACROSS THE SOUTHERN QUARTER TO THIRD OF CENTRAL PA. BEST CHC STILL APPEARS TO BE ACROSS THE LOWER SUSQ VALLEY DURING THE MID AFTERNOON TO EARLY EVENING. MAX TEMPS THIS AFTERNOON WILL VARY FROM ONLY NEAR 70F ACROSS THE NORTHWEST MOUNTAINS...TO THE UPPER 80S IN THE SE ZONES. DEWPOINTS WILL MAKE FOR ONE LAST VERY UNCOMFORTABLE DAY BEFORE DRIER AIR ARRIVES LATER TONIGHT. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... EVENING SHRA/TSRA ACROSS THE SE COUNTIES WILL GIVE WAY TO CLEARING SKIES LATE TONIGHT...AS COLD FRONT SETTLES SOUTH OF THE STATE AND HIGH PRES/LOW PWAT AIR WORKS IN FROM THE WEST. THE CLEARING SKIES AND LGT WIND SHOULD PROMOTE AREAS OF LATE NIGHT FOG IN THE VALLEYS OF WESTERN PA. ANY EARLY FOG SHOULD GIVE WAY TO MSUNNY AND MUCH LESS HUMID WX SUNDAY...AS HIGH PRES PASSES NORTH OF PA. GEFS MEAN 925 TEMPS SUPPORT MAX TEMPS FROM THE U60S OVR THE HIGH TERRAIN OF THE ALLEGHENIES...TO THE U70S ACROSS THE LOWER SUSQ VALLEY. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... BULK OF MED RANGE GUIDANCE INDICATES A CLOUDIER AND PERHAPS SHOWERY MON/TUE THAN WAS EARLIER THOUGHT...AS SHORTWAVE AND ASSOC WEAK WAVE OF LOW PRES SLIDES JUST SOUTH OF PA. TIMING OF THIS FEATURE IN GEFS OUTPUT SUGGESTS THE BEST CHANCE FOR A FEW -SHRA WILL COME LATE MONDAY INTO EARLY TUESDAY ACROSS SOUTHERN PA. FAIRLY GOOD AGREEMENT LATE WEEK AMONGST MED RANGE MDLS...ALL OF WHICH TRACK A DEEPENING SFC LOW WEST OF PA THRU THE GRT LKS. TRAILING COLD FRONT AND ASSOC SHOWER THREAT IS LIKELY TO COME THRU CENTRAL PA THURSDAY. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS PREVAILING THROUGH LATE MORNING WITH MID TO HIGH CLOUD CIGS STREAMING IN AHEAD OF AN APPROACHING COLD FRONT. COLD FRONT IS PROGGED TO ENTER THE NW MTNS LATE THIS MORNING...THEN SLIDE SE ACROSS THE REST OF CENTRAL PA DURING THE AFTN AND EARLY EVENING HOURS. TIMING OF FRONT CONTINUES TO SUGGEST BAND OF SHRA WILL MOVE INTO THE NW MTNS BTWN 12Z-15Z. MORNING SHOWERS ACROSS THE NW MTNS SHOULD PUSH SE AND TRANSITION/GROW INTO NUMEROUS +SHRA AND A FEW BKN LINES OF TSRA IN THE AFTERNOON OVR THE SERN HALF OF THE FCST AREA...WHERE EARLY HEATING WILL RESULT IN A MODERATELY UNSTABLE PRE-FRONTAL AIR MASS BY AFTN. ADDED VCTS TO ALL TAFS EXCEPT KBFD FOR SEVERAL HOURS THIS AFTERNOON...AND LOCAL RESTRICTIONS ARE LIKELY IN HEAVIER SHOWERS/TSTMS. FROPA MAY BRING ANOTHER BAND OF SHOWERS BEFORE ACTIVITY TAPERS OFF THIS AFTERNOON AND EVENING. CONDITIONS IMPROVE BEHIND THE FRONT...THOUGH MVFR CIGS COULD LINGER WELL INTO THE EVENING IN THE WESTERN HIGHER TERRAIN. CLEARING SKIES AND TRAPPED MOISTURE COULD BRING REDUCTIONS TO CIGS/VSBYS LATER TONIGHT INTO SUNDAY MORNING. OUTLOOK... SUN...AM FOG POSS. MON...PATCHY AM VALLEY FOG POSS. TUE...CHC SHOWERS/TSTMS. WED...SCT SHOWERS/TSTMS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DEVOIR/FITZGERALD NEAR TERM...DEVOIR/FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD/GARTNER AVIATION...DEVOIR/RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1048 AM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL PUSH SOUTHEAST ACROSS THE STATE THIS AFTERNOON AND TONIGHT. HIGH PRESSURE OVER THE MIDWEST WILL THEN SLIDE ACROSS PENNSYLVANIA SUNDAY INTO EARLY NEXT WEEK...AS A WEAK LOW PRESSURE SYSTEM TRACKS SOUTH OF PENNSYLVANIA AND OFF THE MID ATLANTIC COAST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CLEAR SKIES EXTEND FROM FRANKLIN TO LANCASTER COUNTIES AT MID TO LATE MORNING...ENABLING SFC TEMPS TO WARM TO THE LOWER 80S AS OF 10 AM. EARLIER FOG HAS DISSIPATED. MID TO HIGH CLOUD CONVECTIVE DEBRIS FROM OVERNIGHT SQUALL LINE DISSIPATING EXTENDS FROM WV THROUGH THE LAUREL HIGHLANDS NORTHEASTWARD TO THE POCONO PLATEAU. SCT-BKN LAYERED CLOUDS EXTEND FROM THE WEST CENTRAL MOUNTAINS NORTHWARD ACROSS THE REMAINDER OF NORTH CENTRAL PA AHEAD OF THE SLOWLY APPROACHING FRONTAL ZONE...WHICH APPEARS WILL CROSS PA IN TWO DISTINCT PIECES TODAY...ACCORDING TO 4KM SPC WRF IDEA AND EXTRAPOLATING CURRENT RADAR VIEW. LATEST REGIONAL RADAR MOSAIC INDICATES AN INITIAL NARROW BAND OF SHOWERS FROM NORTHEAST OHIO THROUGH NORTHWEST PA AND INTO THE FINGERLAKES REGION OF WESTERN NY...SLOWLY PUSHING SOUTHEASTWARD. NEW HRRR AND 00Z 4KM SPC WRF TAKES THIS INITIAL BATCH OF SHOWERS ACROSS THE NORTHWEST THIRD TO HALF OF CENTRAL PA THROUGH 16-17Z...THEN DISSIPATES IT IN FAVOR OF THE FRONTAL ZONE CONVECTION WHICH AGAIN TRACKS ACROSS THE NORTHWEST MOUNTAINS FROM THE EARLY TO MID AFTERNOON HOURS AND REACHES THE CENTRAL MOUNTAINS MID TO LATE AFTERNOON. EARLIER HRRR HAS TRENDED TOWARDS 4KM SPC WRF DEPICTION...AND IS NOT LONGER DEPICTING CONVECTION POSSIBLE AT ANY TIME FROM MID TO LATE MORNING ONWARD ACROSS ALL BUT FAR SOUTHEAST PA AS THE EARLIER MORNING RUN HAD. ISOLATED ACTIVITY IS LIKELY TO SPROUT OVER THE LOWER SUSQ IN THE AREA OF MAX SFC HEATING THIS MORNING (TEMPS WHILE WRITING THIS ARE LIKELY TO WARM INTO THE MID 80S AT THE TOP OF NEXT HOUR)...BUT THINK THE MAIN ACTIVITY WILL COME WITH THE ACTUAL FRONT LATER THIS AFTERNOON AND EVENING. MODIFIED TIMING OF HIGHER CONVECTIVE POPS LATER THIS MORNING AND AFTERNOON BASED ON CURRENT RADAR ACTIVITY AND LATEST HRRR...WHICH AS MENTIONED TOWARDS THE OVERNIGHT 4KM SPC WRF TIMING. THIS DELAYS THE HIGHEST CONVECTIVE POPS ACROSS CENTRAL PA TO ~20Z OR AFTERWARDS. MORNING SHOWERS ACROSS THE NORTHWEST MOUNTAINS WILL PUSH SOUTHEAST AND TRANSITION INTO NUMEROUS +SHRA AND A FEW BKN LINES OF TSRA IN THE AFTERNOON OVR THE SERN HALF OF THE AREA. FARTHER NORTH...THE MAIN FRONTAL BAND OF CONVECTION SHOULD INTENSITY EARLY TO MID AFTERNOON OVER THE NORTHWEST MOUNTAINS AND SLIDE SOUTHEASTWARD INTO THE CENTRAL MOUNTAINS MID TO LATE AFTERNOON. AS EARLIER MENTIONED...SREF PROB FOR CAPES EXCEEDING 2000 J/KG RAMP UP QUICKLY IN THE 15-18Z TIMEFRAME ALONG AND EAST OF A LINE FROM NEAR KJST...TO KUNV AND KELM. ISOLATED SEVERE IS POSSIBLE...LATEST SPC OUTLOOK KEEPS SCHUYLKILL...NORTHUMBERLAND... MONTOUR COLUMBIA AND SULLIVAN COUNTIES IN DAY 1 SLIGHT RISK AREA. SHEAR APPEARS TO BE LACKING FOR WIDESPREAD SEVERE WEATHER...BUT SOME STORMS WILL AT LEAST BE MARGINAL WITH AN ISOLATED THREAT OF SEVERE WIND GUSTS...ESPECIALLY ACROSS THE SOUTHERN QUARTER TO THIRD OF CENTRAL PA. BEST CHC STILL APPEARS TO BE ACROSS THE LOWER SUSQ VALLEY DURING THE MID AFTERNOON TO EARLY EVENING. MAX TEMPS THIS AFTERNOON WILL VARY FROM ONLY NEAR 70F ACROSS THE NORTHWEST MOUNTAINS...TO THE UPPER 80S IN THE SE ZONES. DEWPOINTS WILL MAKE FOR ONE LAST VERY UNCOMFORTABLE DAY BEFORE DRIER AIR ARRIVES LATER TONIGHT. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... EVENING SHRA/TSRA ACROSS THE SE COUNTIES WILL GIVE WAY TO CLEARING SKIES LATE TONIGHT...AS COLD FRONT SETTLES SOUTH OF THE STATE AND HIGH PRES/LOW PWAT AIR WORKS IN FROM THE WEST. THE CLEARING SKIES AND LGT WIND SHOULD PROMOTE AREAS OF LATE NIGHT FOG IN THE VALLEYS OF WESTERN PA. ANY EARLY FOG SHOULD GIVE WAY TO MSUNNY AND MUCH LESS HUMID WX SUNDAY...AS HIGH PRES PASSES NORTH OF PA. GEFS MEAN 925 TEMPS SUPPORT MAX TEMPS FROM THE U60S OVR THE HIGH TERRAIN OF THE ALLEGHENIES...TO THE U70S ACROSS THE LOWER SUSQ VALLEY. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... BULK OF MED RANGE GUIDANCE INDICATES A CLOUDIER AND PERHAPS SHOWERY MON/TUE THAN WAS EARLIER THOUGHT...AS SHORTWAVE AND ASSOC WEAK WAVE OF LOW PRES SLIDES JUST SOUTH OF PA. TIMING OF THIS FEATURE IN GEFS OUTPUT SUGGESTS THE BEST CHANCE FOR A FEW -SHRA WILL COME LATE MONDAY INTO EARLY TUESDAY ACROSS SOUTHERN PA. FAIRLY GOOD AGREEMENT LATE WEEK AMONGST MED RANGE MDLS...ALL OF WHICH TRACK A DEEPENING SFC LOW WEST OF PA THRU THE GRT LKS. TRAILING COLD FRONT AND ASSOC SHOWER THREAT IS LIKELY TO COME THRU CENTRAL PA THURSDAY. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... REDUCTIONS IN FOG/LOW CLOUDS PERSIST ACROSS THE EAST FROM KIPT- KMDT-KLNS AT 12Z. THESE WILL GRADUALLY IMPROVE TO MVFR BY 13-14Z AND EVENTUALLY TO VFR BY LATE MORNING. VFR CONDITIONS ACROSS THE WEST WITH HIGH CLOUDS STREAMING IN AHEAD OF AN APPROACHING COLD FRONT. COLD FRONT IS PROGGED TO ENTER THE NW MTNS LATE THIS MORNING...THEN SLIDE SE ACROSS THE REST OF CENTRAL PA DURING THE AFTN AND EARLY EVENING HOURS. TIMING OF FRONT CONTINUES TO SUGGEST BAND OF SHRA WILL MOVE INTO THE NW MTNS BTWN 12Z-15Z. MORNING SHOWERS ACROSS THE NW MTNS SHOULD PUSH SE AND TRANSITION/GROW INTO NUMEROUS +SHRA AND A FEW BKN LINES OF TSRA IN THE AFTERNOON OVR THE SERN HALF OF THE FCST AREA...WHERE EARLY HEATING WILL RESULT IN A MODERATELY UNSTABLE PRE-FRONTAL AIR MASS BY AFTN. ADDED VCTS TO ALL TAFS EXCEPT KBFD FOR SEVERAL HOURS THIS AFTERNOON...AND LOCAL RESTRICTIONS ARE LIKELY IN HEAVIER SHOWERS/TSTMS. FROPA MAY BRING ANOTHER BAND OF SHOWERS BEFORE ACTIVITY TAPERS OFF THIS AFTERNOON AND EVENING. CONDITIONS IMPROVE BEHIND THE FRONT...THOUGH MVFR CIGS COULD LINGER WELL INTO THE EVENING IN THE WESTERN HIGHER TERRAIN. CLEARING SKIES AND TRAPPED MOISTURE COULD BRING REDUCTIONS TO CIGS/VSBYS LATER TONIGHT INTO SUNDAY MORNING. OUTLOOK... SUN...AM FOG POSS. MON...PATCHY AM VALLEY FOG POSS. TUE...CHC SHOWERS/TSTMS. WED...SCT SHOWERS/TSTMS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DEVOIR/FITZGERALD NEAR TERM...DEVOIR/FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD/GARTNER AVIATION...RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
849 AM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL PUSH SOUTHEAST ACROSS THE STATE LATE TODAY. HIGH PRESSURE OVER THE MIDWEST WILL THEN SLIDE ACROSS PENNSYLVANIA SUNDAY INTO EARLY NEXT WEEK...AS A WEAK LOW PRESSURE SYSTEM TRACKS SOUTH OF PENNSYLVANIA AND OFF THE MID ATLANTIC COAST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CLEAR SKIES FROM FRANKLIN TO LANCASTER COUNTIES ENABLED PATCHY DENSE FOG TO DEVELOP EARLY THIS MORNING...WHICH SHOULD SLOWLY MIX OUT BY 930 AM. MID TO HIGH CLOUD CONVECTIVE DEBRIS FROM LATE EVENING SQUALL LINE OVER THE EASTERN LAKES AND FAR NORTHWEST PA EXTENDS FROM SRN OHIO THROUGH THE POCONO PLATEAU REGION. LAYERED SCT TO BROKEN CLOUDS EXTEND FROM THE WEST CENTRAL MOUNTAINS NORTHWARD ACROSS THE REMAINDER OF NORTH CENTRAL PA AHEAD OF THE SLOWLY APPROACHING FRONTAL ZONE...WHICH APPEARS WILL CROSS PA IN TWO DISTINCT PIECES TODAY...ACCORDING TO 4KM SPC WRF IDEA AND EXTRAPOLATING CURRENT RADAR VIEW. LATEST REGIONAL RADAR MOSAIC INDICATES AN INITIAL NARROW BAND OF SHOWERS FROM NORTHEAST OHTO THE NW PA AND WESTERN NY LAKE ERIE SHORE WHICH WILL DROP INTO THE NORTHWEST MOUNTAINS THIS MORNING. THE AFOREMENTIONED 4KM SPC WRF BRINGS AN INITIAL BATCH OF SHOWERS ACROSS THE NORTHWEST THIRD TO HALF OF CENTRAL PA THROUGH 16Z...THEN DISSIPATES IT IN FAVOR OF THE FRONTAL ZONE CONVECTION WHICH AGAIN TRACKS ACROSS THE NORTHWEST MOUNTAINS FROM THE EARLY TO MID AFTERNOON HOURS AND REACHES THE CENTRAL MOUNTAINS MID TO LATE AFTERNOON. HRRR SEEMS TO BE EXHIBITING ITS TYPICAL BIAS OF OVER-INITIATING CONVECTION IN WEAK FORCING ENVIRONMENTS AND SUGGESTS CONVECTION IS POSSIBLE AT ANY TIME FROM MID TO LATE MORNING ONWARD ACROSS ALL BUT FAR SOUTHEAST PA. WHILE IT`S A POSSIBILITY GIVEN AVAILABLE CAPE...AM CONSIDERING THIS AN OUTLIER FOR NOW WITHOUT DISCOUNTING IT. MODIFIED TIMING OF HIGHER CONVECTIVE POPS LATER THIS MORNING AND AFTERNOON TOWARDS THE 4KM SPC WRF TIMING...WHICH PRODUCED A SLIGHT DELAY IN ONSET OF GREATEST AREAL COVERAGE BY 1-2 HOURS. EARLIER THINKING OF MORNING SHOWERS ACROSS THE NW MTNS PUSHING SE AND TRANSITIONING INTO NUMEROUS +SHRA AND A FEW BKN LINES OF TSRA IN THE AFTERNOON OVR THE SERN HALF OR SO OF THE FCST AREA IS STILL IN PLAY. GREATEST SFC HEATING WILL TAKE PLACE OVER THE LOWER SUSQ THIS MORNING RESULTING IN MODERATELY UNSTABLE PRE-FRONTAL ENVIRONMENT THIS AFTERNOON. AS EARLIER MENTIONED...SREF PROB FOR CAPES EXCEEDING 2000 J/KG RAMP UP QUICKLY IN THE 15-18Z TIMEFRAME ALONG AND EAST OF A LINE FROM NEAR KJST...TO KUNV AND KELM. SHEAR APPEARS TO BE LACKING FOR WIDESPREAD SEVERE WEATHER...BUT SOME STORMS WILL AT LEAST BE MARGINAL WITH AN ISOLATED THREAT OF SEVERE WIND GUSTS...ESPECIALLY ACROSS THE SOUTHERN QUARTER TO THIRD OF CENTRAL PA. BEST CHC STILL APPEARS TO BE ACROSS THE LOWER SUSQ VALLEY DURING THE MID AFTERNOON TO EARLY EVENING. MAX TEMPS THIS AFTERNOON WILL VARY FROM ONLY NEAR 70F ACROSS THE NORTHWEST MOUNTAINS...TO THE UPPER 80S IN THE SE ZONES. DEWPOINTS WILL MAKE FOR ONE LAST VERY UNCOMFORTABLE DAY BEFORE DRIER AIR ARRIVES LATER TONIGHT. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... EVENING SHRA/TSRA ACROSS THE SE COUNTIES WILL GIVE WAY TO CLEARING SKIES LATE TONIGHT...AS COLD FRONT SETTLES SOUTH OF THE STATE AND HIGH PRES/LOW PWAT AIR WORKS IN FROM THE WEST. THE CLEARING SKIES AND LGT WIND SHOULD PROMOTE AREAS OF LATE NIGHT FOG IN THE VALLEYS OF WESTERN PA. ANY EARLY FOG SHOULD GIVE WAY TO MSUNNY AND MUCH LESS HUMID WX SUNDAY...AS HIGH PRES PASSES NORTH OF PA. GEFS MEAN 925 TEMPS SUPPORT MAX TEMPS FROM THE U60S OVR THE HIGH TERRAIN OF THE ALLEGHENIES...TO THE U70S ACROSS THE LOWER SUSQ VALLEY. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... BULK OF MED RANGE GUIDANCE INDICATES A CLOUDIER AND PERHAPS SHOWERY MON/TUE THAN WAS EARLIER THOUGHT...AS SHORTWAVE AND ASSOC WEAK WAVE OF LOW PRES SLIDES JUST SOUTH OF PA. TIMING OF THIS FEATURE IN GEFS OUTPUT SUGGESTS THE BEST CHANCE FOR A FEW -SHRA WILL COME LATE MONDAY INTO EARLY TUESDAY ACROSS SOUTHERN PA. FAIRLY GOOD AGREEMENT LATE WEEK AMONGST MED RANGE MDLS...ALL OF WHICH TRACK A DEEPENING SFC LOW WEST OF PA THRU THE GRT LKS. TRAILING COLD FRONT AND ASSOC SHOWER THREAT IS LIKELY TO COME THRU CENTRAL PA THURSDAY. && .AVIATION /13Z SATURDAY THROUGH WEDNESDAY/... REDUCTIONS IN FOG/LOW CLOUDS PERSIST ACROSS THE EAST FROM KIPT- KMDT-KLNS AT 12Z. THESE WILL GRADUALLY IMPROVE TO MVFR BY 13-14Z AND EVENTUALLY TO VFR BY LATE MORNING. VFR CONDITIONS ACROSS THE WEST WITH HIGH CLOUDS STREAMING IN AHEAD OF AN APPROACHING COLD FRONT. COLD FRONT IS PROGGED TO ENTER THE NW MTNS LATE THIS MORNING...THEN SLIDE SE ACROSS THE REST OF CENTRAL PA DURING THE AFTN AND EARLY EVENING HOURS. TIMING OF FRONT CONTINUES TO SUGGEST BAND OF SHRA WILL MOVE INTO THE NW MTNS BTWN 12Z-15Z. MORNING SHOWERS ACROSS THE NW MTNS SHOULD PUSH SE AND TRANSITION/GROW INTO NUMEROUS +SHRA AND A FEW BKN LINES OF TSRA IN THE AFTERNOON OVR THE SERN HALF OF THE FCST AREA...WHERE EARLY HEATING WILL RESULT IN A MODERATELY UNSTABLE PRE-FRONTAL AIR MASS BY AFTN. ADDED VCTS TO ALL TAFS EXCEPT KBFD FOR SEVERAL HOURS THIS AFTERNOON...AND LOCAL RESTRICTIONS ARE LIKELY IN HEAVIER SHOWERS/TSTMS. FROPA MAY BRING ANOTHER BAND OF SHOWERS BEFORE ACTIVITY TAPERS OFF THIS AFTERNOON AND EVENING. CONDITIONS IMPROVE BEHIND THE FRONT...THOUGH MVFR CIGS COULD LINGER WELL INTO THE EVENING IN THE WESTERN HIGHER TERRAIN. CLEARING SKIES AND TRAPPED MOISTURE COULD BRING REDUCTIONS TO CIGS/VSBYS LATER TONIGHT INTO SUNDAY MORNING. OUTLOOK... SUN...AM FOG POSS. MON...PATCHY AM VALLEY FOG POSS. TUE...CHC SHOWERS/TSTMS. WED...SCT SHOWERS/TSTMS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD NEAR TERM...DEVOIR/FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD/GARTNER AVIATION...RXR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
838 AM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL PUSH SOUTHEAST ACROSS THE STATE LATE TODAY. HIGH PRESSURE OVER THE MIDWEST WILL THEN SLIDE ACROSS PENNSYLVANIA SUNDAY INTO EARLY NEXT WEEK...AS A WEAK LOW PRESSURE SYSTEM TRACKS SOUTH OF PENNSYLVANIA AND OFF THE MID ATLANTIC COAST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CLEAR SKIES FROM FRANKLIN TO LANCASTER COUNTIES ENABLED PATCHY DENSE FOG TO DEVELOP EARLY THIS MORNING...WHICH SHOULD SLOWLY MIX OUT BY 930 AM. MID TO HIGH CLOUD CONVECTIVE DEBRIS FROM LATE EVENING SQUALL LINE OVER THE EASTERN LAKES AND FAR NORTHWEST PA EXTENDS FROM SRN OHIO THROUGH THE POCONO PLATEAU REGION. LAYERED SCT TO BROKEN CLOUDS EXTEND FROM THE WEST CENTRAL MOUNTAINS NORTHWARD ACROSS THE REMAINDER OF NORTH CENTRAL PA AHEAD OF THE SLOWLY APPROACHING FRONTAL ZONE...WHICH APPEARS WILL CROSS PA IN TWO DISTINCT PIECES TODAY...ACCORDING TO 4KM SPC WRF IDEA AND EXTRAPOLATING CURRENT RADAR VIEW. LATEST REGIONAL RADAR MOSAIC INDICATES AN INITIAL NARROW BAND OF SHOWERS FROM NORTHEAST OHTO THE NW PA AND WESTERN NY LAKE ERIE SHORE WHICH WILL DROP INTO THE NORTHWEST MOUNTAINS THIS MORNING. THE AFOREMENTIONED 4KM SPC WRF BRINGS AN INITIAL BATCH OF SHOWERS ACROSS THE NORTHWEST THIRD TO HALF OF CENTRAL PA THROUGH 16Z...THEN DISSIPATES IT IN FAVOR OF THE FRONTAL ZONE CONVECTION WHICH AGAIN TRACKS ACROSS THE NORTHWEST MOUNTAINS FROM THE EARLY TO MID AFTERNOON HOURS AND REACHES THE CENTRAL MOUNTAINS MID TO LATE AFTERNOON. HRRR SEEMS TO BE EXHIBITING ITS TYPICAL BIAS OF OVER-INITIATING CONVECTION IN WEAK FORCING ENVIRONMENTS AND SUGGESTS CONVECTION IS POSSIBLE AT ANY TIME FROM MID TO LATE MORNING ONWARD ACROSS ALL BUT FAR SOUTHEAST PA. WHILE IT`S A POSSIBILITY GIVEN AVAILABLE CAPE...AM CONSIDERING THIS AN OUTLIER FOR NOW WITHOUT DISCOUNTING IT. MODIFIED TIMING OF HIGHER CONVECTIVE POPS LATER THIS MORNING AND AFTERNOON TOWARDS THE 4KM SPC WRF TIMING...WHICH PRODUCED A SLIGHT DELAY IN ONSET OF GREATEST AREAL COVERAGE BY 1-2 HOURS. EARLIER THINKING OF MORNING SHOWERS ACROSS THE NW MTNS PUSHING SE AND TRANSITIONING INTO NUMEROUS +SHRA AND A FEW BKN LINES OF TSRA IN THE AFTERNOON OVR THE SERN HALF OR SO OF THE FCST AREA IS STILL IN PLAY. GREATEST SFC HEATING WILL TAKE PLACE OVER THE LOWER SUSQ THIS MORNING RESULTING IN MODERATELY UNSTABLE PRE-FRONTAL ENVIRONMENT THIS AFTERNOON. AS EARLIER MENTIONED...SREF PROB FOR CAPES EXCEEDING 2000 J/KG RAMP UP QUICKLY IN THE 15-18Z TIMEFRAME ALONG AND EAST OF A LINE FROM NEAR KJST...TO KUNV AND KELM. SHEAR APPEARS TO BE LACKING FOR WIDESPREAD SEVERE WEATHER...BUT SOME STORMS WILL AT LEAST BE MARGINAL WITH AN ISOLATED THREAT OF SEVERE WIND GUSTS...ESPECIALLY ACROSS THE SOUTHERN QUARTER TO THIRD OF CENTRAL PA. BEST CHC STILL APPEARS TO BE ACROSS THE LOWER SUSQ VALLEY DURING THE MID AFTERNOON TO EARLY EVENING. MAX TEMPS THIS AFTERNOON WILL VARY FROM ONLY NEAR 70F ACROSS THE NORTHWEST MOUNTAINS...TO THE UPPER 80S IN THE SE ZONES. DEWPOINTS WILL MAKE FOR ONE LAST VERY UNCOMFORTABLE DAY BEFORE DRIER AIR ARRIVES LATER TONIGHT. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... EVENING SHRA/TSRA ACROSS THE SE COUNTIES WILL GIVE WAY TO CLEARING SKIES LATE TONIGHT...AS COLD FRONT SETTLES SOUTH OF THE STATE AND HIGH PRES/LOW PWAT AIR WORKS IN FROM THE WEST. THE CLEARING SKIES AND LGT WIND SHOULD PROMOTE AREAS OF LATE NIGHT FOG IN THE VALLEYS OF WESTERN PA. ANY EARLY FOG SHOULD GIVE WAY TO MSUNNY AND MUCH LESS HUMID WX SUNDAY...AS HIGH PRES PASSES NORTH OF PA. GEFS MEAN 925 TEMPS SUPPORT MAX TEMPS FROM THE U60S OVR THE HIGH TERRAIN OF THE ALLEGHENIES...TO THE U70S ACROSS THE LOWER SUSQ VALLEY. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... BULK OF MED RANGE GUIDANCE INDICATES A CLOUDIER AND PERHAPS SHOWERY MON/TUE THAN WAS EARLIER THOUGHT...AS SHORTWAVE AND ASSOC WEAK WAVE OF LOW PRES SLIDES JUST SOUTH OF PA. TIMING OF THIS FEATURE IN GEFS OUTPUT SUGGESTS THE BEST CHANCE FOR A FEW -SHRA WILL COME LATE MONDAY INTO EARLY TUESDAY ACROSS SOUTHERN PA. FAIRLY GOOD AGREEMENT LATE WEEK AMONGST MED RANGE MDLS...ALL OF WHICH TRACK A DEEPENING SFC LOW WEST OF PA THRU THE GRT LKS. TRAILING COLD FRONT AND ASSOC SHOWER THREAT IS LIKELY TO COME THRU CENTRAL PA THURSDAY. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... LINE OF SHOWERS AND SCT TSTMS OUTRAN ITS UPPER LEVEL SUPPORT AND HAS WEAKENED OVER THE PAST SEVERAL HOURS /05Z-08Z/ AS IT PUSHED ACROSS THE NW MTNS. MODELS INDICATE CONVECTION SHOULD CONTINUE TO DISSIPATE DURING THE PRE-DAWN HOURS. SO IMPACTS FOR REMAINDER OF THE OVERNIGHT SHOULD BE LIMITED TO AREAS OF FOG AND LOW CLOUDS MAINLY ACROSS THE SUSQ VALLEY FROM KLNS-KMDT-KIPT...WHERE IFR CONDITIONS WILL BECOME MORE COMMON. REDUCTIONS FROM FOG/LOW CLOUDS WILL PERSIST INTO THE MID MORNING ACROSS THE EAST...BUT CONDITIONS SHOULD EVENTUALLY RETURN TO VFR BY LATE MORNING. ELSEWHERE...MID-HIGH CLOUDS SHOULD PRECLUDE ANY MAJOR REDUCTIONS...WITH JUST SCT MVFR FOG POSS. COLD FRONT APPROACHES AFTER SUNRISE AND SLOWLY CROSSES THE REGION THROUGH THE DAY. EXPECT SHOWERS WITH INTERMITTANT RESTRICTIONS TO WORK SOUTHEASTWARD AND TRANSITION INTO SHOWERS AND A FEW BROKEN LINES OF TSRA. BIGGEST IMPACTS WILL BE FROM 12Z INTO THE MID/LATE MORNING AROUND KBFD...LATE MORNING THROUGH MID AFTERNOON IN THE CENTRAL MTNS FROM KJST-KAOO- KUNV- KIPT...AND AFTER 18Z IN THE LOWER SUSQ NEAR KMDT-KLNS. CONDITIONS IMPROVE BEHIND THE FRONT...THOUGH MVFR CIGS COULD LINGER IN THE WESTERN HIGHER TERRAIN. CLEARING SKIES AND TRAPPED MOISTURE COULD BRING REDUCTIONS TO CIGS/VSBYS LATER TONIGHT INTO SUNDAY MORNING. OUTLOOK... SUN...AM FOG POSS. MON...PATCHY AM VALLEY FOG POSS. TUE...CHC SHOWERS/TSTMS. WED...SCT SHOWERS/TSTMS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...FITZGERALD NEAR TERM...DEVOIR/FITZGERALD SHORT TERM...FITZGERALD LONG TERM...FITZGERALD/GARTNER AVIATION...RXR
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
743 AM EDT SAT SEP 6 2014 .SYNOPSIS... A STRONG COLD FRONT WILL PUSH THROUGH OUR AREA TODAY AND THIS EVENING...HELPING TO IGNITE SCATTERED TO NUMEROUS SHOWERS AND STORMS. THIS FRONT WILL STALL SOUTH OF THE REGION THROUGH EARLY NEXT WEEK...KEEPING CLOUDS ALONG WITH THE THREAT FOR SHOWERS...BUT COOLER TEMPERATURES. && .NEAR TERM /THROUGH TONIGHT/... AS OF 730 AM EDT SATURDAY... OVERALL NEAR TERM FORECAST IS NOT BAD. UPDATED TO ADJUST POPS DOWNWARD THIS MORNING. A FEW SHOWERS LINGERING OVER TOWARD BLF. MAINLY DEALING WITH FOG IN THE WEST WHICH SHOULD BURN OFF HERE IN BY 10-11 AM. STILL LOOKS LIKE MAIN INITIATION OF CONVECTION OCCURS AFTER 16Z. PREVIOUS VALID DISCUSSION... A COLD FRONT ENTERS THE WESTERN PORTION OF OUR FORECAST AREA AROUND 18Z...AND TRIES TO EXIT THE FAR SOUTHEAST PORTION OF OUR FORECAST AREA BETWEEN 00Z- 06Z TONIGHT. AS THE BOUNDARY BECOMES PARALLEL TO THE UPPER FLOW...ITS SOUTHWARD PROGRESSION WILL SLOW. IN ADVANCE OF THIS FRONT...A WESTERLY COMPONENT TO THE LOW LEVEL WINDS SHOULD ALLOW FOR SOME CLEARING TODAY AS WELL AS DESTABILIZATION. FORECAST 0-6KM SHEAR VALUES INCREASE TO 20-25KTS AFTER 21Z...SO SOME STORM ORGANIZATION IS EXPECTED. IN ADDITION TO THE POTENTIAL FOR LOCALLY HEAVY RAINS WITH PWAT VALUES STILL 1-2 STANDARD DEVIATIONS ABOVE NORMAL TODAY...A SMALL DAMAGING WIND THREAT EXISTS...WHICH WILL BE NOTED IN THE HAZARDOUS WEATHER OUTLOOK. COVERAGE OF SHOWERS AND STORMS SHOULD ONLY BE WIDELY SCATTERED IN ADVANCE OF THE FRONT WITH A WEAK SOUTHWEST/WEST LOW LEVEL WIND...AND GFS MAY BE OVERDONE WITH PRECIP COVERAGE AT 18Z. PLACED HIGHEST POPS LATER IN THE DAY WHEN THE BETTER LOW LEVEL CONVERGENCE ARRIVES WITH THE FRONT. THE GFS MOS IS ONCE AGAIN SIGNIFICANTLY WARMER THAN MOST GUIDANCE FOR HIGHS TODAY. WITH SOME CLEARING AND WEAK DOWNSLOPE WIND...HIGHS TODAY SHOULD BE WARMER THAN VALUES ON FRIDAY. HOWEVER...WITH INCREASING CLOUDS TODAY...USED A BLEND OF THE NAM/GFS MOS. BY 12Z SUNDAY...THE SFC FRONT IS FORECAST TO BE IN CENTRAL NC...BUT PRECIPITATION IN THE SOUTHEAST PORTION OF THE FORECAST AREA WILL LIKELY BE SLOW TO END WITH THE SLOW MOVEMENT OF THE FRONT...ALONG WITH GOOD UPPER LEVEL DIVERGENCE ASSOCIATED WITH A RR QUAD OF AN UPPER LEVEL JET MOVING THROUGH THE EASTERN GREAT LAKES AND NEW ENGLAND. LOW CLOUDS AND AND LIGHT PRECIP WELL TO THE NORTH OF THE BOUNDARY WILL BE POSSIBLE AS WEDGE BEGINS TO BUILD. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... AS OF 330 AM EDT SATURDAY... OVERALL LOOKS LIKE A DAMP/WEDGE PATTERN FOR US THIS PERIOD. MODELS ARE DIFFERING ON STRENGTH/POSITION OF A SFC LOW OVER THE SE COAST SUN-TUE...BUT PER TRENDS/WPC GUIDANCE THE 00Z ECMWF/GFS SEEM IN THE BALL PARK ON THIS SYSTEM. DIFFERENCES BETWEEN THESE MODELS LIES IN THE QPF FIELD. THE GFS SEEMS INLAND TOO MUCH WITH QPF MONDAY...THINKING A LOT OF DEEP MOISTURE WILL RESIDE ACROSS THE COASTLINE WITH CONVECTION AND HENCE ROB SOME INFLOW INTO OUR NECK OF THE WOODS. FOR SUNDAY...THE SFC LOW WILL BE OVER GEORGIA/SOUTH CAROLINA WHILE SFC HIGH STRETCHES FROM IA/MO ENE INTO WRN PA/NY. THE FLOW WILL TURN MORE NE-E WITH INCREASING MOISTURE. SFC FRONT WILL BE SOUTHEAST OF US ACROSS ERN NC...BUT SW FLOW ALOFT COMBINED WITH EASTERLY FLOW WILL KEEP MOISTURE INFLOW INTO OUR REGION WITH HIGHER THREAT ALONG THE SRN BLUE RIDGE SUNDAY AFTERNOON. THE SFC HIGH MOVES QUICKLY NE AND SETS UP OVER NEW ENGLAND/SRN QUEBEC SUNDAY NIGHT WITH FRONTAL SYSTEM REMAINING ALONG THE COAST...WITH INVERTED TROUGH IN ERN TN. FAVORING A BETTER THREAT OF SHOWERS EAST OF THE BLUE RIDGE SUNDAY NIGHT OVER INTO MONDAY NIGHT...AS THE LOW SLIDES SLOWLY NWD ACROSS ERN NC THEN OFF THE VA COAST. THE MODELS START TO SHOW DRIER AIR WORKING IN FROM THE WEST TUESDAY MORNING...WITH DEEP MOISTURE SHIFTING OUT TO SEA. TUESDAY WILL BE A DRIER DAY BUT MODELS SHOWING ANOTHER SYSTEM MOVING INTO THE SRN PLAINS WITH UPPER SHORTWAVE SHIFTING ALONG THE NRN EDGE OF THE RIDGE THAT REMAINS OVER THE GULF COAST INTO OUR REGION. ATTM...NOT TOO IMPRESSED WITH PRECIP CHANCES TUESDAY WITH MAINLY AFTERNOON/EVENING SHOWERS AND STORMS SCATTERED ACROSS THE BLUE RIDGE AND ADJACENT COUNTIES WEST INTO THE WV MOUNTAINS. TEMPS THIS PERIOD REMAIN TRICKY BUT WILL MOS SEEMS TO HAVE A DECENT HANDLE ON HIGHS. SUNDAY WILL BE TRANSITION DAY...BUT WILL SEE HIGHS MAINLY IN THE 70S BEHIND THE FRONT WITH NE WINDS. IF PRECIP IS MORE WIDESPREAD HIGHS MONDAY MAY NOT GET OUT OF THE 60S IN THE EAST. FOR NOW I AM LEANING TOWARD THE MAV WHICH HAS HIGHS FROM THE LOWER TO MID 70S IN THE WEST TO UPPER 70S/LOWER 80S ACROSS THE FAR SW CWA...WITH SOME 60S IN BLUE RIDGE HIGHER TERRAIN AS WELL AS THE ALLEGHANYS. TUESDAY WILL BE WARMER WITH FLOW WEAKENING AND TURNING MORE NNW. HIGHS WILL RANGE FROM THE MID TO UPPER 70S WEST TO LOWER 80S SOUTHEAST. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... AS OF 400 PM EDT FRIDAY... ON WEDNESDAY...A COLD FRONT SWEEPS ACROSS THE NORTHERN PLAINS WITH A SURFACE WAVE TRACKING NORTHEAST TOWARDS THE GREAT LAKES. AS THIS WAVE MOVES INTO ZONAL FLOW...IT WILL THEN TRACK OVER THE OHIO VALLEY WEDNESDAY AFTERNOON/EVENING. THIS WAVE WILL KEEP BULK OF THE STRONGER CONVECTION NORTH IN THE OHIO VALLEY. AS THIS WAVE ENTERS THE OHIO VALLEY...THE WEDGE THAT WAS OVER THE MID ATLANTIC REGION MONDAY AND TUESDAY WILL BEGIN TO ERODE. IF THIS WEDGE REMAINS DRY WHILE IN THE AREA...IT SHOULD HAVE NO PROBLEMS ERODING WEDNESDAY. IF THIS WEDGE HAS RAIN TO ENHANCE IT...IT MAY NOT CLEAR THE AREA UNTIL LATE WEDNESDAY NIGHT. MODELS ARE PUSHING THIS COLD FRONT ACROSS THE REGION ON THURSDAY. AS IN THE CASE WITH THE FRONT EARLY IN THE WEEK...DOES THIS FRONT CLEAR THE FORECAST AREA OR DOES IT STALL IN THE VICINITY. SINCE THIS FRONT IS TRYING TO TRACK SOUTH IN ZONAL FLOW...THE POSSIBILITIES OF A SLOWER ARRIVAL (FRIDAY AND/OR SATURDAY) OR HAVING THE FRONT STALL OVER THE REGION IS HIGH. SINCE THIS IS POSSIBLE...WILL KEEP CHANCE POPS IN FOR FRIDAY. AREAS THAT HANG ON TO THE WEDGE WEDNESDAY WILL HAVE COOLER THAN NORMAL TEMPERATURES. IF OUTSIDE THE WEDGE...AT OR ABOVE NORMAL TEMPERATURES ARE LIKELY. THE WARMEST DAY OF THE WEEK SHOULD BE THURSDAY...ESPECIALLY IF THE FRONT IS SLOW TO TRACK EAST. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 735 AM EDT SATURDAY... FOG WILL BE DENSE AT BCB/LWB THIS MORNING...LIFTING TO MVFR/IFR BY 14-15Z...AND ALL VFR BY 15-16Z. OTHERWISE...EXPECTING AN SOMEWHAT ACTIVE AFTERNOON THOUGH NOT WIDESPREAD CONVECTION...BUT ENOUGH CONFIDENCE TO HAVE A FEW HOURS OF SHOWERS WITH VCTS IN THE TAFS. WINDOW OF TSRA WILL BE IN THE 19-23Z TIME FRAME AND HAVE TEMPO GROUPS OF 2 HOURS OR LESS FOR THUNDER AT ROA/BCB/BLF/LWB...LESS COVERAGE FURTHER EAST. THIS ACTIVITY WITH THE FRONT WEAKENS BY EARLY EVENING 00-02Z...WITH FOG DEVELOPING ONCE AGAIN. QUESTION WILL BE EXTENT OF HIGHER CLOUDS. THINK VALLEYS IN THE WEST WILL SINK AGAIN TO IFR/LIFR OVERNIGHT...WHILE ELSEWHERE CAN EXPECT HIGH END IFR/LOW END MVFR. THE FRONT WILL BE STALLED JUST SOUTH OF THE AREA SUNDAY AND MONDAY...MAINTAINING CLOUD COVER AS WELL AS A THREAT FOR SHOWERS. MEANWHILE LOW PRESSURE MOVING ALONG THE SOUTHEAST COAST WILL KEEP OUR WINDS NE. THIS LOW MOVES OUT BY TUESDAY WITH A RETURN TO MORE DIURNAL SHOWERS AND STORMS. WITH WEDGE IN PLACE SUN-MON THINK SUB VFR IS HIGHER ESPECIALLY FROM BCB/ROA/LWB AND EAST. WEDGE BREAKS TUESDAY SO EXPECT VFR OUTSIDE ANY SHOWERS/STORMS AND LATE NIGHT FOG. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PH NEAR TERM...PH/WP SHORT TERM...WP LONG TERM...RCS AVIATION...PH/WP
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1043 AM MDT SAT SEP 6 2014 .UPDATE... ISSUED AT 940 AM MDT SAT SEP 6 2014 THE FOG IS DONE OR NEARLY SO AT THIS TIME...HOWEVER THERE IS A STRATUS FIELDS STILL IN PLACE OVER SOME OF THE URBAN CORRIDOR AND THE PALMER RIDGE. THE CEILINGS ARE COMING UP SLOWLY AND THERE IS SOME EROSION OF THE FIELD. THE ACARS SOUNDINGS SHOW THE PLAINS TO BE PRETTY STABLE...SO WILL NOT HAVE MANY POPS FOR THE THERE. THERE IS SOME CONVECTIVE CLOUDINESS STARTING TO DEVELOP OVER THE MOUNTAINS. WILL MAKE SOME MINOR ADJUSTMENTS IN CLOUDS. THE RAP AND HRRR SHOWS VERY LITTLE CONVECTION IN THE MOUNTAINS THIS AFTERNOON AND EVENING. MAY LOWER MOUNTAIN POPS A BIT AS WELL. WILL LEAVE TEMPERATURES AS IS FOR NOW. && .SHORT TERM...(TODAY THROUGH TONIGHT ) ISSUED AT 345 AM MDT SAT SEP 6 2014 MUCH OF THE STRATUS HAS DISSIPATED OVER THE FRONT RANGE WHILE A BATCH OF MID LEVEL CLOUDS CONTINUES TO STREAM OVER THE AREA. TEMPERATURE AND DEWPOINT SPREADS ARE STILL LOW AND EXPECT ONCE THIS MID LEVEL DECK PASSES THAT MORE FOG WILL DEVELOP THOUGH LOW CONFIDENCE ON HOW EXTENSIVE IT WILL BECOME AFTER SUNRISE. OVERALL MOISTURE LEVELS HAVE DROPPED A FEW TENTHS FROM YESTERDAY BUT STILL EXPECT SCATTERED THUNDERSTORM ACTIVITY IN THE MOUNTAINS AND FOOTHILLS WITH SOME MOISTURE CONVERGENCE AND SLIGHT INSTABILITY. RIDGING ALOFT WILL BE BUILDING OVER COLORADO WITH CONTINUED WEAK SUBSIDENCE. THERE IS LIGHTNING STILL ONGOING OVER NRN UTAH SO SOME OF THIS WILL DRIFT INTO THE NORTHERN MOUNTAINS THIS AFTERNOON. A FEW STORMS WILL DRIFT OVER THE URBAN CORRIDOR AND PALMER DIVIDE. SURFACE BASED CAPES UNDER 500J/KG SO STORMS WILL BE GENERALLY BE ON THE WEAK SIDE WITH BRIEF RAIN AND GUSTY WINDS. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 345 AM MDT SAT SEP 6 2014 ON SUN THE FLOW ALOFT WILL BE WNW. THE ECMWF SHOWS SOME MID LVL MOISTURE EMBEDDED IN THIS FLOW WILL THE GFS IS DRIER. AFTN CAPES WILL RANGE FM 500-1000 J/KG MAINLY OVER NERN CO. WILL KEEP IN A SLIGHT CHC OF AFTN/EVENING TSTMS OVER THE HIGHER TERRAIN AND ACROSS THE PLAINS. AS FOR HIGHS WILL SEE 5 TO 6 DEGREES OF WARMING IN THE 850-700 MB LYR SO AFTN HIGHS SHOULD RISE INTO THE LOWER TO MID 80S OVER NERN CO. ON MON THE FLOW ALOFT WILL BECOME MORE WSW AS SOME TROPICAL MOISTURE FM NORBERT GETS ENTRAINED INTO THE MID LVL FLOW. THIS SHOULD LEAD TO A BETTER CHC FOR SHOWERS AND STORMS OVER THE HIGHER TERRAIN WITH SOME OF THIS ACTIVITY SPREADING ACROSS THE PLAINS MON NIGHT. HIGHS ON MON WILL BE SIMILAR TO SUN WITH READINGS IN THE LOWER TO MID 80S ACROSS THE PLAINS. FOR TUE INTO TUE NIGHT APPEARS A WK UPPER LEVEL TROUGH WILL MOVE ACROSS THE AREA WHICH SHOULD ALLOW FOR A GOOD CHC OF SHOWERS AND STORMS OVER THE HIGHER TERRAIN WITH A CHC OVER NERN CO. AS FOR HIGHS READINGS MAY BE A FEW DEGREES COOLER OVER NERN CO WITH TEMPS IN THE UPPER 70S TO LOWER 80S. BY WED THE WK UPPER LEVEL TROUGH WILL MOVE EAST OF THE AREA WITH A DRIER AIRMASS SPREADING INTO THE RGN. MEANWHILE A COLD FNT WILL MOVE INTO NERN CO WHICH WILL DROP READINGS INTO THE LOWER TO MID 70S. OVERALL THE THREAT FOR TSTMS LOOKS LOWER ON WED DUE TO LESS INSTABILITY AND A DRIER AIRMASS OVER THE AREA SO WILL ONLY MENTION ISOLD TO WDLY SCT TSTMS. FOR WED NIGHT INTO THU THE FLOW ALOFT WILL BE NWLY AS A STRONGER FNT MOVES INTO NERN CO. WILL SEE INCREASING UPSLOPE FLOW AND IF THERE IS A DISTURBANCE EMBEDDED IN THE FLOW THIS COULD LEAD TO A CHC OF SHOWERS. TEMPS WILL BE COOLER ON THU WITH READINGS ONLY IN THE 60S OVER NERN CO. IT COULD BE EVEN COLDER IF SKIES REMAIN OVERCAST ALL DAY WHICH WOULD KEEP HIGHS ONLY IN THE 50S. BY FRI DRY NW FLOW ALOFT WILL BE OVER THE AREA AS A SFC HIGH MOVES INTO THE CENTRAL PLAINS. AFTN HIGHS WILL STILL REMAIN BLO NORMAL WITH HIGHS IN THE 65 TO 70 DEGREE RANGE OVER NERN CO. && .AVIATION...(FOR THE TAFS THROUGH 18Z SUNDAY MORNING) ISSUED AT 940 AM MDT SAT SEP 6 2014 SATELLITE PICTURES ARE SHOWING A STRATA-CUMULUS FIELD OVER THE AIRPORT RIGHT NOW. THE CEILINGS SHOULD GO THE SCATTERED BY 18Z. WINDS WILL E INSIGNIFICANT...UNDER 10 KNOTS AND LIKELY FROM THE EAST UNTIL DRAINAGE KICKS IN THIS EVENING. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...RJK SHORT TERM...ENTREKIN LONG TERM...RPK AVIATION...RJK
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1217 PM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT CROSSING OHIO IS POISED TO MOVE THROUGH OUR REGION THIS EVENING...STALLING OFFSHORE THROUGH MID-WEEK... WHILE HIGH PRESSURE IN THE CENTRAL PLAINS SPREADS TO OUR NORTH. LOW PRESSURE IN SOUTH CAROLINA SUNDAY WILL DEVELOP NORTHEASTWARD OFF THE MID ATLANTIC COAST LATE TUESDAY AND BE POSITIONED EAST OF CAPE COD BY LATE WEDNESDAY. ANOTHER COLD FRONT WILL MOVE EASTWARD THROUGH OUR REGION LATE THURSDAY OR FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LOW CLOUDS HAVE DISSIPATED BUT AN ABUNDANCE OF HIGH CLOUDS WITH SOME MID CLOUDS WAS EVIDENT ON STLT IMAGERY OVER PA. THESE CLOUDS WERE MOVG EWD. LTST RADAR IMAGERY STILL HAD NOTHING, PSBLY AS A RESULT OF THE EARLIER LOW CLOUDS. HRRR ALREADY HAD PRECIP OVER OUR NWRN AREAS, WHICH IS NOT THERE. SO, HAVE BACKED PRECIP UP A FEW MORE HOURS AND LOWERED POPS IN THE REAL NEAR TERM AS WELL. OTHERWISE, MADE SOME ADJUSTMENTS TO CLOUD COVER. TEMPS GENLY LOOKED GOOD. OVERALL FOR TODAY WE ARE EXPECTING AN INCREASE IN SHOWER AND THUNDERSTORM ACTIVITY BY THE LATE AFTERNOON/EARLY EVENING TIMEFRAME. THE COLD FRONT DRUDGING THROUGH THE GREAT LAKES AT THIS TIME WILL BEGIN TO SLOW ITS SOUTHEAST PROGRESSION JUST A BIT THIS AFTERNOON AS THE MID-LEVEL FLOW FLATTENS OUT SOME. AMPLE MOISTURE AND INSTABILITY AHEAD OF THE FRONT WILL ALLOW FOR RAPID STORM GROWTH. MODEST MID-LEVEL LAPSE RATES AND SHEAR WILL BE AN ISSUE FOR BETTER ORGANIZATION OF CELLS THOUGH WITH THE HIGH PWAT AIR IN PLACE, RAIN LOADED CORES CAN DROP AND PRODUCE GUSTY, POSSIBLY DAMAGING WINDS THIS AFTERNOON. BETTER SHEAR PROFILES EXIST TO OUR NORTHEAST WHERE STRONGER WINDS ALOFT ARE. SPC CONTINUES THE SLIGHT RISK FOR OUR NORTHERN ZONES WHERE BETTER ORGANIZATION MAY EXIST, THOUGH JUST ABOUT ANYWHERE IN OUR CWA COULD SEE PULSE STRONG TO SEVERE WIND GUSTS. THE GFS DID SLIGHTLY BETTER THAN THE NAM IN THE THERMAL INITIALIZATION DEPARTMENT THIS MORNING.TEMPERATURES TODAY WERE A BLEND OF THE MET/MAVMOS WITH A SLIGHT HEAVIER WEIGHING ON THE MAV. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM SUNDAY/... CONTINUED SHOWERY ACTIVITY WITH EMBEDDED CONVECTION WILL PUSH SOUTHEAST ALONG THE COLD FRONT LATE THIS EVENING. HEAVY RAIN WITH THE SHOWERS WILL REMAIN THE LARGEST THREAT THOUGH WE SHOULD HAVE ENOUGH LINGERING LOW-LEVEL INSTABILITY TO SEE SOME STRONGER WIND GUSTS WITH THE SHOWERS. WE SLOWED THE PROGRESSION OF THE DECREASING POPS ACROSS OUR SOUTH JUST A BIT AS WE EXPECT THE FRONT TO SLOW SOME DURING THE DAY. BEHIND THE FRONT NORTH-NORTHWEST WINDS WILL BRING IN A MUCH DRIER AIRMASS AS DEWPOINTS ARE EXPECTED TO FALL INTO THE MID-50S. THERE LOOKS TO BE TOO MUCH MIXING LATE TONIGHT TO ALLOW FOR FOG FORMATION, EXCEPT WITHIN THE MORE SHELTERED RIVER VALLEYS. LOWS TONIGHT WERE A BLEND OF THE MET/MAV WITH MORE WEIGHTING ON THE SLIGHTLY WARMER MET WITH MORE MIXING TAKING PLACE. && .LONG TERM /SUNDAY THROUGH FRIDAY/... 500 MB: HEIGHTS RISE/WARM WITH SHORT WAVE RIDGING FOLLOWING THE DEPARTURE OF THE QUEBEC SHORT WAVE SUNDAY INTO MONDAY. THE NEXT SHORT WAVE CROSSES THE MID ATLANTIC STATES LATE TUESDAY OR EARLY WEDNESDAY. STRONG SHORT WAVES APPEAR LIKELY TO ROTATES NEWD THROUGH THE GREAT LAKES REGION LATE IN THE WEEK...PRODUCING A WARMING TREND ALONG THE MID ATLANTIC COAST. TEMPERATURES: SEPTEMBER SO FAR (FIRST 5 DAYS) HAS AVERAGED WELL ABOVE NORMAL....GENERALLY 6-7 DEGREES. THE DAILY AVERAGES WILL COOL TO NEAR NORMAL SUNDAY-TUESDAY THEN WARM ABOVE NORMAL AGAIN WEDNESDAY-FRIDAY. TEMPS MAY AVERAGE MORE THAN 5 DEGREES ABOVE NORMAL THURSDAY AND FRIDAY. FORECAST BASIS: UNLESS OTHERWISE NOTED THE LONG TERM PERIOD OF THIS FORECAST IS GENERALLY BASED ON A 50 50 BLEND OF THE 00Z/6 NAM/GFS MOS FOR THE PERIOD SUNDAY-MONDAY...THE 00Z/6 GFS MOS MONDAY NIGHT AND TUESDAY...THEN THEREAFTER (TUESDAY NIGHT ONWARD) THE 0543Z/06 WPC GRIDDED GUIDANCE WHICH AT TIMES IS BLENDED 50 50 WITH THE 00Z/6 MEXMOS. ALL THIS IS EVENTUALLY CHECKED AGAINST THE 00Z/6 ECMWF TO SEE IF WE`RE IN THE BALLPARK WITH ECMWF CYCLICALLY PERSISTENT 18Z 2 METER TEMPERATURES. THE PRECIPITATION PROBABILITY GUIDANCE IS CHECKED AGAINST THE 21Z/5 SREF POPS FOR .01 IN 3 HRS THROUGH 12Z TUESDAY AND THEREAFTER THE 00Z/6 GEFS 6HR POPS FOR 0.05 THE DAILIES BELOW... SUNDAY...A VERY NICE DAY IN THE WAKE OF TODAYS SUMMERTIME HEAT. MUCH LESS HUMID AND COOLER WITH PLENTY OF BRIGHT SUNSHINE. ANY SHOWERS EARLY IN THE DAY ON THE SOUTHEAST EDGE OF OUR AREA SHOULD END BY FORENOON. MONDAY-TUESDAY...BECOMES PROBLEMATIC FROM SOUTH TO NORTH AS LOW PRESSURE ALONG THE SOUTH CAROLINA COAST NEEDS TO BE MONITORED FOR ITS FUTURE TRACK AND STRENGTHENING. AS IT STANDS NOW...A STIFF EAST TO NORTHEAST OCEAN INFLOW SHOULD SPREAD CLOUDS AND THEN SHOWERS OR BANDS OF RAIN NORTHWARD. DETAILS ON COVERAGE OF SHOWERS AND AMOUNTS ARE STILL EARLY BUT THIS PERIOD OF TIME DESERVES TO BE MONITORED AS A POTENTIALLY SIGNIFICANT EARLY SEPTEMBER PERIOD OF NASTY WEATHER...AT LEAST ALONG THE COAST! REGARDING THE LOW...PLEASE NOTE NHC HAS THIS AS A 10 TO 20 PCT CHANCE OF TROPICAL CYCLONE FORMATION EARLY THIS COMING WEEK. WED-FRI...TIMING DIFFERENCES BUT PULSES OF INSTABILITY BURSTS IN RESPONSE TO STRONG SHORT WAVES ROTATING NEWD THROUGH THE GREAT LAKES REGION OFFER CHANCE OF SHOWERS FROM TIME TO TIME BUT MOST OF THE TIME SHOULD BE RAIN-FREE. WE TENDED TO RUN WARMER THAN THE 0543Z WPC TEMPERATURE GUIDANCE...MORE IN LINE WITH THE WARMER 00Z/6 GFS MEX MOS AND ECMWF 2M TEMPS. AGAIN THE FOCUS THIS WEEK SHOULD BE ON MONDAY NIGHT-TUESDAY EVENING FOR COASTAL NJ/DE RESIDENTS AND MARINERS. && .AVIATION /16Z SATURDAY THROUGH WEDNESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THE STUBBORN LOW CLOUDS FROM THIS MRNG HAVE DISSIPATED AND EVERYONE IS NOW VFR. EXPECT VFR TO CONTINUE UNTIL ANY SHRA/TSRA LATER. SOUTHWEST FLOW INCREASES WITH SOME GUSTS POSSIBLE. COLD FRONT SLIDES IN FROM THE NORTHWEST TOUCHING OFF SHOWERS AND THUNDERSTORMS DURG THE AFTN/EVE. LOOKS LIKE A GOOD CHANCE FOR WIDESPREAD THUNDERSTORM ACTIVITY BY LATE AFTERNOON WITH BRIEF MVFR/IFR RESTRICTIONS. CONTINUED SHOWER ACTIVITY POSSIBLE A FEW HOURS AFTER FRONTAL PASSAGE. TONIGHT...VFR. WINDS VEER TO THE NORTH-NORTHWEST BRINGING IN DRIER AIR. SHOWERS CUT OFF BY LATE TONIGHT ACROSS THE SOUTHERN TERMINALS. OUTLOOK... SUNDAY...VFR. LIGHT NORTH WIND TRENDING EAST LATE DAY. MONDAY - TUESDAY...VFR CIGS TO START MONDAY BUT PERIODS OF MVFR CONDS EXPECTED IN BANDS OF SHOWERS AT LEAST ALONG THE COAST WHERE BRIEF IFR CONDS MIGHT DEVELOP? E-NE WIND GUST 20-30 KT...HIGHEST GUSTS COAST. WEDNESDAY...MOSTLY VFR BUT LOCALLY MVFR/IFR IN SCATTERED SHOWERS AND TSTMS LATE DAY OR AT NIGHT. LIGHT WIND BECOMING SOUTH. && .MARINE... SUB-SCA CONDITIONS ARE EXPECTED ACROSS OUR WATERS TODAY THOUGH WE COULD SEE GUSTS UPWARDS OF 20 KNOTS BY THE AFTERNOON HOURS. SOUTHWEST WINDS WILL VEER TOWARDS THE WEST-NORTHWEST LATE TONIGHT AS A COLD FRONT PUSHES THROUGH. SEAS AHEAD OF THE FRONT WILL CLIMB TO 3-4 FEET BEFORE SUBSIDING A BIT BEHIND THE FRONT. GUSTY NORTHWEST WINDS ARE POSSIBLE BEHIND THE FRONT...STILL AROUND 20 KNOTS EXPECTED. OUTLOOK... SUNDAY...NO HEADLINE ANTICIPATED. MONDAY AND TUESDAY...STRONG SCA EXPECTED EXCEPT A MORE MARGINAL SCA POSSIBLE UPPER DELAWARE BAY. POTENTIAL FOR 35KT - GALE FORCE GUSTS. WEDNESDAY...SCA SEAS MAY LINGER ALONG THE ATLANTIC COASTAL WATERS DURING THE MORNING DESPITE LIGHT WINDS. DE BAY SHOULD NOT NEED A A MARINE HAZARD HEADLINE. && .TIDES/COASTAL FLOODING... FAIRLY STRONG AND LONG DURATION ONSHORE FLOW COMBINED WITH ASTRONOMICALLY HIGH TIDE CYCLES AS WE MOVE THROUGH THE SEPTEMBER SUPERMOON PHASE. SURGE OF A FOOT PROBABLE FOR THE MONDAY EVENING AND TUESDAY HIGH TIDE CYCLES SHOULD RESULT IN 2 OR 3 TIDE CYCLES WITH MINOR COASTAL FLOODING. NOT IMPOSSIBLE TO FORESEE SPOTTY MODERATE COASTAL FLOODING BUT THAT MODERATE CF THREAT IS A MUCH A LESSER CHANCE THAN THE MINOR EXCEEDENCES. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...DRAG NEAR TERM...HEAVENER/NIERENBERG SHORT TERM...HEAVENER LONG TERM...DRAG AVIATION...DRAG/HEAVENER/NIERENBERG MARINE...DRAG/HEAVENER TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
251 PM CDT SAT SEP 6 2014 .DISCUSSION... 313 AM CDT THE COLD FRONT ASSOCIATED WITH THE ACTIVE WEATHER ON FRIDAY HAS PUSHED OFF TO THE SOUTHEAST EARLY THIS MORNING. WE STILL HAVE SOME SHOWERS FIRING IN CENTRAL ILLINOIS AND EXTENDING INTO PORTIONS OF NORTHEAST ILLINOIS AND NORTHWEST INDIANA. IT IS THIS AREA WHERE THE LOW TO MID LEVEL BAROCLINIC ZONE STILL LINGERS AS SOME ENERGY GLIDES EASTWARD THROUGH THE BASE OF THE UPPER TROUGH AXIS MOVING THROUGH WESTERN ONTARIO AND EXTENDING INTO THE PORTIONS OF THE MIDWEST. UPPER AIR SOUNDINGS AND WATER VAPOR CONFIRM THE DRIER AIR MASS SET TO INVADE OUR AREA THIS WEEKEND. KMPX 0Z SOUNDING DEPICTED A 1.2 IN PRECIPITABLE WATER DROP IN THE LAST 24 HOURS...AND LOW TO MID 50S DEWPOINTS HAVE ALREADY PUSHED INTO NORTH CENTRAL ILLINOIS. EXPECT THAT TREND TO CONTINUE OVER THE REMAINDER OF THE AREA TODAY. THE BAROCLINIC ZONE WILL CONTINUE TO PRESS EAST AS DRIER NORTHERLY FLOW SETS IN...WITH RAIN SHOWERS MOVING ALONG WITH IT. THE CLOUD SHIELD WILL EVENTUALLY PUSH EASTWARD AS A DRY SHEARED VORTICITY AREA SLIDES ON BY AND SURFACE HIGH PRESSURE IN THE CENTRAL PLAINS HEADS INTO IOWA WITH THE RIDGE AXIS EXTENDING TO THE SOUTHERN GREAT LAKES. HIGHS TOP OFF IN THE LOWER TO MAYBE MID 70S WITH INCREASING SUNSHINE THROUGH THE AFTERNOON. DEWPOINTS WILL BE SOME 15 DEGREES LOWER THAN FRIDAY...MAKING FOR A COMFORTABLE IF NOT "COOL" DAY. EXPECT A LAKE BREEZE TO LIMIT THE WARM UP DOWNTOWN. ON SUNDAY THE FLOW ALOFT IS FAIRLY ZONAL ACROSS MUCH OF THE COUNTRY WITH NO NOTICEABLE VORT MAXES. MEANWHILE SURFACE HIGH PRESSURE BUILDS OVER THE GREAT LAKES BY MIDDAY THEN OFF TO THE EASTERN GREAT LAKES BY MONDAY MORNING. THIS WILL MAKE FOR ANOTHER DELIGHTFUL EARLY METEOROLOGICAL AUTUMN AFTERNOON WITH PLENTIFUL SUNSHINE...MILD AND DRY CONDITIONS. AND WINDS WILL BE ON THE LIGHTER SIDE TOO. HIGHS WILL TOP OFF IN THE MID 70S..UP A FEW DEGREES FROM SATURDAY. THE NEXT REAL FORCING WILL BE EMANATING FROM A CURRENTLY RETROGRADING CUTOFF LOW OFF THE NORTHERN CALIFORNIA COAST...WITH ENERGY EVENTUALLY MIGRATING EASTWARD IN THE UPPER JET. AS SURFACE HIGH PRESSURE CONTINUES EAST...RETURN FLOW DEVELOPS IN THE PLAINS INCREASING MOISTURE TRANSPORT TO OUR WEST. MEDIUM RANGE MODELS A SUBTLE WAVE THAT COMBINED WITH INCREASED WARM ADVECTION IN IOWA THAT LOOKS TO INITIATE CONVECTION LATER MONDAY. AS THE WAVE TRACKS EASTWARD...SOME DIFFERENCES EMERGE AS TO WHETHER THUNDERSTORMS WILL MAKE IT INTO NORTHEAST ILLINOIS AS THE GFS SUGGESTS OR LARGELY GRAZE THE AREA LIKE THE EC/NAM. RECENT HISTORY HAS SHOWN THESE SUBTLE SYSTEMS MAKING BETTER EASTWARD PROGRESS THAN ANTICIPATED...SO WILL CONTINUE WITH CHANCE POPS UNTIL GUIDANCE LATCHES ON TO SOMETHING MORE DEFINITIVE. ON TUESDAY...THE LEE TROUGHING THAT DEVELOPS AHEAD OF THIS FIRST WAVE EVENTUALLY GETS A SHOVE EAST AS THE MEAN TROUGH IN THE WEST GETS SOME MOVEMENT. A SHARP UPPER TROUGH WILL REMAIN WELL NORTH IN CANADA...BUT SOME OF THE COOLER CANADIAN AIR LOOKS TO GET DISLODGED A WILL DEVELOP A COLD FRONT ALONG THE INTERNATIONAL BORDER THAT WILL SHIFT INTO MINNESOTA. MODELS/ENSEMBLES THEN DEVELOP A DECENT EARLY AUTUMN SURFACE LOW THAT WILL TRACK ALONG THIS BOUNDARY SOMEWHERE THROUGH THE GREAT LAKES REGION INTO WEDNESDAY. MODELS GENERALLY AGREE ON THE TIMING BUT VARY CONSIDERABLY ON THE STRENGTH OF THE LOW THAT DEVELOPS. THERE ARE HINTS THAT SOME OF THE MOISTURE FROM HURRICANE NORBERT OFF OF BAJA CALIFORNIA MAY GET EMBEDDED IN THE WESTERLY FLOW. EITHER WAY...THE LOW LEVEL WIND FIELD RESPONDS AND COMBINES WITH A NICE FEED OF MOISTURE (PW`S > 2"). FORECAST SOUNDINGS DEPICT A DEEP MOIST COLUMN SUGGESTIVE OF SHOWERS WITH EMBEDDED THUNDERSTORMS WITH A HEAVY RAINFALL POTENTIAL. HAVE PUT IN LIKELY POPS FOR THE TUESDAY NIGHT INTO WEDNESDAY MORNING PERIOD TO ACCOUNT FOR DECENT MODEL AGREEMENT AT THIS TIME THOUGH A NUMBER OF UPSTREAM DEPENDENCIES WILL INFLUENCE THE TRACK AND STRENGTH OF THIS SYSTEM. THE WESTERN UPPER TROUGH WILL BE LAGGING BEHIND THIS SHORTWAVE TROUGH AND WILL SLOWLY PROGRESS THROUGH FOR THE LATTER HALF OF THE WEEK...LEADING TO BELOW NORMAL TEMPERATURES AND SMALL CHANCES FOR RAIN SHOWERS. SURFACE HIGH PRESSURE SHOULD BE REDEVELOPING DURING THIS TIME AND THUS THE LOWER PRECIP POTENTIAL. KMD && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 20Z... * NONE IZZI //DISCUSSION...UPDATED 20Z... SOMEWHAT ILL-DEFINED LAKE BREEZE BOUNDARY EXTENDS FROM JUST EAST OF ORD TO JJUST WEST OF MDW. WINDS SOMEWHAT VARIABLE FROM THE NORTH OR NORTHEAST ON EITHER SIDE OF THE BOUNDARY...SO EVEN IF IT WERE TO WOBBLE WEST FARTHER WOULD ANTICIPATE PREVAILING WINDS TO REMAIN LESS THAN 10KT. IZZI UPDATED 18Z... ONE AND ONLY FORECAST CHALLENGE THIS AFTERNOON IS WITH WIND DIRECTION THIS AFTERNOON INTO VERY EARLY EVENING. LAKE BREEZE HAS BEGUN TO SHOW UP ON TERMINAL DOPPLER AND ANTICIPATE THAT IT WILL MAKE A PUSH INLAND THIS AFTERNOON. ORIENTATION OF THE LAKE BREEZE FAVORS A PASSAGE AND STEADY NE WIND DEVELOPING FOR A TIME AT MDW. FAR LESS CERTAINTY REGARDING POSSIBLE LAKE BREEZE PASSAGE AT ORD SO PLAN TO RUN WITH MORE STRAIGHT NORTHERLY IN THE TAF BUT WILL MONITOR FOR POSSIBLE LAKE BREEZE PASSAGE LATE THIS AFTERNOON. OTHERWISE...VFR CONDITIONS EXPECTED. IZZI //ORD AND MDW CONFIDENCE...UPDATED 20Z... * HIGH CONFIDENCE IN ALL ELEMENTS IZZI //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT THROUGH MONDAY...VFR. SLGT CHANCE TSRA LATE MONDAY NIGHT. TUESDAY THROUGH THURSDAY...PERIODIC CHANCES OF SHRA/TSRA... ESPECIALLY TUESDAY NIGHT INTO WEDNESDAY. FRIDAY...VFR. RATZER && .MARINE... 247 PM CDT HIGH PRESSURE CENTERED OVER THE SOUTHERN PLAINS WILL EXPAND EASTWARD ACROSS THE GREAT LAKES INTO SUNDAY BEFORE IT EVOLVES FURTHER EAST AND BECOMES CENTERED OVER THE ST. LAWRENCE RIVER VALLEY MONDAY. A WEAK COOL FRONT CROSSING THE NORTHERN PART OF THE LAKE THIS AFTERNOON HAS BROUGHT AN INCREASE IN WIND SPEED ACROSS THE NORTH BUT THE HIGH SPREADING IN WILL ALLOW SPEEDS TO DIMINISH THIS EVENING AND TURN SOUTHERLY OVERNIGHT. THE DIRECTION WILL BE MORE VARIABLE SOUTH BUT SPEEDS WILL SLACKEN AS WELL ALLOWING WAVES TO SUBSIDE. WILL GO AHEAD AND CARRY THAT SMALL CRAFT ADVISORY UNTIL 7 PM CDT AS SCHEDULED. SOUTHERLY WINDS WILL GRADUALLY BECOME STEADIER SUNDAY AND SUNDAY NIGHT...ESPECIALLY ACROSS CENTRAL AND NORTHERN SECTIONS...AS THE HIGH SHIFTS EAST AND WEAK LOW PRESSURE MOVES INTO THE CENTRAL AND NORTHERN PLAINS. THE GRADIENT WILL LIKELY BE WEAK ENOUGH TO SUPPORT A SHIFT TO ONSHORE FLOW ACROSS THE SOUTHERN PART OF THE LAKE SUNDAY AFTERNOON. THE BIGGEST FORECAST CONCERN COMES AS AN UPPER TROUGH DIGS INTO THE CENTRAL U.S. TUESDAY HELPING SURFACE LOW PRESSURE INTENSIFY AND MOVE NORTHEAST FROM THE CENTRAL PLAINS TO THE WESTERN GREAT LAKES WEDNESDAY. THIS SYSTEM WILL BEAR CLOSE WATCH AS THE UPPER FLOW PATTERN IS EXPECTED TO BECOME QUITE AMPLIFIED SUPPORTING A RAPID DEEPENING OF THE SYSTEM. HAVE ALREADY SEEN VARIABILITY IN HOW MEDIUM RANGE GUIDANCE HAS HANDLED THIS SYSTEM BUT THE TREND HAS BEEN TO BE STRONGER. STILL TOO EARLY FOR DETAILS BUT A DEEPENING LOW TRACKING NEAR OR NORTH OF THE LAKE IS PRIME TO PRODUCE GALES SO THE FIRST SIGNIFICANT SYSTEM OF THE SEASON MAY BE IN THE MAKING. WILL NEED TO WATCH THIS SYSTEM CLOSELY OVER THE NEXT FEW DAYS AS AN EXTENDED PERIOD OF LOWER END GALES AND A SHORTER PERIOD OR PERIODS OF MID OR EVEN HIGH END GALES IS PLAUSIBLE. FOR NOW WILL MENTION POSSIBLE GALES GIVEN THE TIME RANGE OF THE FORECAST AT THIS POINT. HIGH PRESSURE WOULD LIKELY BUILD IN BEHIND THE SYSTEM LATE NEXT WEEK OR EARLY NEXT WEEKEND. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 7 PM SATURDAY. LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 7 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 101 PM CDT Sat Sep 6 2014 .UPDATE... ISSUED AT 1051 AM CDT SAT SEP 6 2014 Persistent stratus deck behind the frontal boundary that passed through last night very slow to clear. Concerned for the high temps in the far SE. In the last couple hours, the clouds have started to progress slightly to the SE and less concerned with the highs in the NW, but still have a ways to go with temps lingering in the 60s through mid morning. Will only make slight adjustments in the NW...possibly a couple degrees in the SE. Some minor and sct showers remain in the far SE and see no reason to pull the mention, and will continue to adjust to trends. Updates out momentarily. && .SHORT TERM...(Today) ISSUED AT 259 AM CDT SAT SEP 6 2014 Despite passage of a cold front during the evening hours, scattered light showers persist across the southern two-thirds of the KILX CWA early this morning. NAM/GFS/ECMWF have all verified too far north with lingering precip field at 06z, while the latest HRRR seems to have the best handle on the current situation. Following the latest radar trends and HRRR solution, have maintained low chance PoPs along/south of I-70 into the early afternoon before showers gradually push further southward into the Ohio River Valley. Meanwhile further north, have gone with a dry forecast across the remainder of the CWA. Skies will start out mostly cloudy, followed by a steady clearing trend from north to south as the day progresses. Afternoon high temperatures will be quite a bit cooler than yesterday, with readings remaining in the lower to middle 70s. && .LONG TERM...(Tonight through Friday) ISSUED AT 259 AM CDT SAT SEP 6 2014 High pressure will build into the region tonight into Sunday, resulting in clear skies and cool temperatures. Light winds/dry airmass will allow excellent radiational cooling to take place tonight, with lows bottoming out in the lower to middle 50s. On the flip side, full sunshine acting on the dry airmass will help temperatures rebound nicely into the middle to upper 70s on Sunday. Once the upper trough responsible for the cool weather lifts into eastern Canada, an active zonal flow pattern will develop across the CONUS next week. Two distinct systems will track through this flow, bringing rain chances to central Illinois. The first is progged to track from the Northern Plains Sunday night into the southern Great Lakes by Tuesday morning. Models are developing showers/storms in advance of this feature Monday night as low-level jet focuses across northern Missouri/southern Iowa. Solutions vary as to how far east into the prevailing surface ridge axis precip will penetrate late Monday night into Tuesday. Given presence of very dry airmass initially and only weak upper support with the short-wave, will keep highest PoPs confined to the Illinois River Valley Monday night. Further east, will go with a dry forecast along/east of I-57. Will only mention low chance PoPs on Tuesday as nocturnal convection undergoes diurnal weakening further eastward into the dry airmass. Second stronger wave will approach Tuesday night into Wednesday, bringing a much better chance for widespread rain. Models are suggesting moisture from tropical system in the Pacific may get drawn into this feature, resulting in unseasonably high precipitable water values in excess of 2 inches. GFS/ECMWF/GEM all bring a hefty slug of precip into Illinois late Tuesday night into Wednesday accordingly: however, axis of heaviest precip still remains in question. Have boosted PoPs to likely across the northern two-thirds of the CWA Tuesday night and Wednesday. Initial QPF from WPC indicates the potential for 1 to 2 inches of rain across much of the area during this time, with the highest amounts across the Illinois River Valley. Once wave passes to the east, strong cold front will settle southward, taking the higher rain chances into the far southern CWA Wednesday night. After that, most model guidance is advertising a cooler/drier day on Thursday followed by a shot of even cooler air by the end of the week. Both the GFS and ECMWF show 850mb temps dropping to around 0c by next Saturday morning, potentially resulting in highs only in the middle to upper 60s and lows dipping into the 40s next weekend. && .AVIATION...(For the 18Z TAFS through 18Z Sunday afternoon) ISSUED AT 1254 PM CDT SAT SEP 6 2014 Persistent stratus remaining in place over Central IL. Slow clearing to the NW just as quickly being filled in with diurnal CU development. PIA should be clearing pretty soon and as long as the trend continues, most sites will be breaking back to VFR within the first few hours and will get updated, with the exception of CMI and DEC which may end up under the stratus for a few more hours. VFR into the overnight anticipated. Concern for the persistent stratus trapping some of the deeper moisture at the sfc through to the early morning hours. Dwpts in the SE still lingering in the 60s and will drive threat for fog in the early morning hours. Have dropped PIA BMI and SPI to MVFR and CMI and DEC to IFR. May be a bit too optimistic depending on how much of this moisture can mix out this afternoon. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HJS SHORT TERM...BARNES LONG TERM...BARNES AVIATION...HJS
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1124 AM CDT SAT SEP 6 2014 .DISCUSSION... 313 AM CDT THE COLD FRONT ASSOCIATED WITH THE ACTIVE WEATHER ON FRIDAY HAS PUSHED OFF TO THE SOUTHEAST EARLY THIS MORNING. WE STILL HAVE SOME SHOWERS FIRING IN CENTRAL ILLINOIS AND EXTENDING INTO PORTIONS OF NORTHEAST ILLINOIS AND NORTHWEST INDIANA. IT IS THIS AREA WHERE THE LOW TO MID LEVEL BAROCLINIC ZONE STILL LINGERS AS SOME ENERGY GLIDES EASTWARD THROUGH THE BASE OF THE UPPER TROUGH AXIS MOVING THROUGH WESTERN ONTARIO AND EXTENDING INTO THE PORTIONS OF THE MIDWEST. UPPER AIR SOUNDINGS AND WATER VAPOR CONFIRM THE DRIER AIR MASS SET TO INVADE OUR AREA THIS WEEKEND. KMPX 0Z SOUNDING DEPICTED A 1.2 IN PRECIPITABLE WATER DROP IN THE LAST 24 HOURS...AND LOW TO MID 50S DEWPOINTS HAVE ALREADY PUSHED INTO NORTH CENTRAL ILLINOIS. EXPECT THAT TREND TO CONTINUE OVER THE REMAINDER OF THE AREA TODAY. THE BAROCLINIC ZONE WILL CONTINUE TO PRESS EAST AS DRIER NORTHERLY FLOW SETS IN...WITH RAIN SHOWERS MOVING ALONG WITH IT. THE CLOUD SHIELD WILL EVENTUALLY PUSH EASTWARD AS A DRY SHEARED VORTICITY AREA SLIDES ON BY AND SURFACE HIGH PRESSURE IN THE CENTRAL PLAINS HEADS INTO IOWA WITH THE RIDGE AXIS EXTENDING TO THE SOUTHERN GREAT LAKES. HIGHS TOP OFF IN THE LOWER TO MAYBE MID 70S WITH INCREASING SUNSHINE THROUGH THE AFTERNOON. DEWPOINTS WILL BE SOME 15 DEGREES LOWER THAN FRIDAY...MAKING FOR A COMFORTABLE IF NOT "COOL" DAY. EXPECT A LAKE BREEZE TO LIMIT THE WARM UP DOWNTOWN. ON SUNDAY THE FLOW ALOFT IS FAIRLY ZONAL ACROSS MUCH OF THE COUNTRY WITH NO NOTICEABLE VORT MAXES. MEANWHILE SURFACE HIGH PRESSURE BUILDS OVER THE GREAT LAKES BY MIDDAY THEN OFF TO THE EASTERN GREAT LAKES BY MONDAY MORNING. THIS WILL MAKE FOR ANOTHER DELIGHTFUL EARLY METEOROLOGICAL AUTUMN AFTERNOON WITH PLENTIFUL SUNSHINE...MILD AND DRY CONDITIONS. AND WINDS WILL BE ON THE LIGHTER SIDE TOO. HIGHS WILL TOP OFF IN THE MID 70S..UP A FEW DEGREES FROM SATURDAY. THE NEXT REAL FORCING WILL BE EMANATING FROM A CURRENTLY RETROGRADING CUTOFF LOW OFF THE NORTHERN CALIFORNIA COAST...WITH ENERGY EVENTUALLY MIGRATING EASTWARD IN THE UPPER JET. AS SURFACE HIGH PRESSURE CONTINUES EAST...RETURN FLOW DEVELOPS IN THE PLAINS INCREASING MOISTURE TRANSPORT TO OUR WEST. MEDIUM RANGE MODELS A SUBTLE WAVE THAT COMBINED WITH INCREASED WARM ADVECTION IN IOWA THAT LOOKS TO INITIATE CONVECTION LATER MONDAY. AS THE WAVE TRACKS EASTWARD...SOME DIFFERENCES EMERGE AS TO WHETHER THUNDERSTORMS WILL MAKE IT INTO NORTHEAST ILLNOIS AS THE GFS SUGGESTS OR LARGELY GRAZE THE AREA LIKE THE EC/NAM. RECENT HISTORY HAS SHOWN THESE SUBTLE SYSTEMS MAKING BETTER EASTWARD PROGRESS THAN ANTICIPATED...SO WILL CONTINUE WITH CHANCE POPS UNTIL GUIDANCE LATCHES ON TO SOMETHING MORE DEFINITIVE. ON TUESDAY...THE LEE TROUGHING THAT DEVELOPS AHEAD OF THIS FIRST WAVE EVENTUALLY GETS A SHOVE EAST AS THE MEAN TROUGH IN THE WEST GETS SOME MOVEMENT. A SHARP UPPER TROUGH WILL REMAIN WELL NORTH IN CANADA...BUT SOME OF THE COOLER CANADIAN AIR LOOKS TO GET DISLODGED A WILL DEVELOP A COLD FRONT ALONG THE INTERNATIONAL BORDER THAT WILL SHIFT INTO MINNESOTA. MODELS/ENSEMBLES THEN DEVELOP A DECENT EARLY AUTUMN SURFACE LOW THAT WILL TRACK ALONG THIS BOUNDARY SOMEWHERE THROUGH THE GREAT LAKES REGION INTO WEDNESDAY. MODELS GENERALLY AGREE ON THE TIMING BUT VARY CONSIDERABLY ON THE STRENGTH OF THE LOW THAT DEVELOPS. THERE ARE HINTS THAT SOME OF THE MOISTURE FROM HURRICANE NORBERT OFF OF BAJA CALIFORNIA MAY GET EMBEDDED IN THE WESTERLY FLOW. EITHER WAY...THE LOW LEVEL WIND FIELD RESPONDS AND COMBINES WITH A NICE FEED OF MOISTURE (PW`S > 2"). FORECAST SOUNDINGS DEPICT A DEEP MOIST COLUMN SUGGESTIVE OF SHOWERS WITH EMBEDDED THUNDERSTORMS WITH A HEAVY RAINFALL POTENTIAL. HAVE PUT IN LIKELY POPS FOR THE TUESDAY NIGHT INTO WEDNESDAY MORNING PERIOD TO ACCOUNT FOR DECENT MODEL AGREEMENT AT THIS TIME THOUGH A NUMBER OF UPSTREAM DEPENDENCIES WILL INFLUENCE THE TRACK AND STRENGTH OF THIS SYSTEM. THE WESTERN UPPER TROUGH WILL BE LAGGING BEHIND THIS SHORTWAVE TROUGH AND WILL SLOWLY PROGRESS THROUGH FOR THE LATTER HALF OF THE WEEK...LEADING TO BELOW NORMAL TEMPERATURES AND SMALL CHANCES FOR RAIN SHOWERS. SURFACE HIGH PRESSURE SHOULD BE REDEVELOPING DURING THIS TIME AND THUS THE LOWER PRECIP POTENTIAL. KMD && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 16Z... * NORTHERLY TO NORTHEASTERLY WINDS TROUGH THIS AFTERNOON IZZI //DISCUSSION...UPDATED 12Z... LOW LEVELS CONTINUE TO DRY OUT WITH NORTH-NORTHWEST WINDS THIS MORNING. A FEW PATCHES OF 2500-3000 FT MVFR LINGER SOUTH OF KMDW AND TOWARDS KGYY...THOUGH THESE SHOULD BE DISSIPATING QUICKLY THIS MORNING WITH VFR CONDITIONS EXPECTED FOR THE REMAINDER OF THE TAF PERIOD. ONLY REAL CONCERN IS WITH THE POTENTIAL FOR A LAKE BREEZE WIND SHIFT THIS AFTERNOON ACROSS MAINLY KMDW AND KGYY. HIGH-RES GUIDANCE TRENDS CONTINUE TO INDICATE KORD TO REMAIN NORTH- NORTHWEST IN 340-360 DEGREE RANGE WHILE WINDS SHIFT TO 010-030 DEGREES AT KMDW AND KGYY. SPEEDS AROUND/SLIGHTLY OVER 10 KT THROUGH MIDDAY AS HIGH PRESSURE BUILDS TOWARD THE REGION...THEN SLACKING THIS AFTERNOON AS GRADIENT WEAKENS IN THE VICINITY OF THE SURFACE RIDGE. WILL HAVE TO WATCH LAKE BREEZE FOR IMPACT ON KORD BUT HAVE KEPT WIND SHIFT EAST OF THERE BASED ON STRONGER GRADIENT WINDS THIS MORNING AND CONTINUED GUIDANCE TRENDS INDICATING NO LAKE BREEZE PASSAGE. OTHERWISE...WINDS DIMINISH QUICKLY EARLY THIS EVENING AND ASSUME A VARIABLE/WESTERLY DIRECTION LESS THAN 5 KT. COULD BE SOME PATCHY MVFR FOG MAINLY OUTSIDE METRO CHICAGO. RATZER //ORD AND MDW CONFIDENCE...UPDATED 16Z... * LOW-MEDIUM CONFIDENCE IN LAKE BREEZE TIMING/INLAND EXTENT. * HIGH CONFIDENCE ALL OTHER ELEMENTS. RATZER/IZZI //OUTLOOK FOR ORD/MDW FOR 00Z MONDAY-12Z SATURDAY...UPDATED 12Z... SUNDAY NIGHT THROUGH MONDAY...VFR. SLGT CHANCE TSRA LATE MONDAY NIGHT. TUESDAY THROUGH THURSDAY...PERIODIC CHANCES OF SHRA/TSRA... ESPECIALLY TUESDAY NIGHT INTO WEDNESDAY. FRIDAY...VFR. RATZER && .MARINE... 259 AM CDT HIGH PRESSURE OVER THE CENTRAL PLAINS WILL MOVE SLOWLY EAST INTO THE MIDWEST TONIGHT AND ACROSS THE LOWER LAKES BY SUNDAY NIGHT. BRIEF PERIOD OF GUSTY NORTH-NORTHWEST WINDS TO 25 KT THIS MORNING AS THE SURFACE HIGH DEVELOPS TOWARD THE LAKE SHOULD RELAX THIS AFTERNOON ESPECIALLY ON SOUTHERN LAKE MICHIGAN WHERE THE RIDGE AXIS WILL RESIDE BY EVENING. FARTHER NORTH...A WEAK LOW WILL PASS ACROSS THE NORTHERN LAKES TONIGHT...BACKING WINDS MORE WESTERLY WITH GUSTS 20-25 KT AGAIN AHEAD OF A WEAK COLD FRONT THIS AFTERNOON...THEN VEERING NORTH TOWARD EVENING AND DIMINISHING. WINDS WILL COME BACK AROUND TO THE SOUTH-SOUTHEAST SUNDAY AND SUNDAY NIGHT AS THE HIGH DRIFTS OFF TO THE EAST ACROSS THE LOWER LAKES INTO NEW ENGLAND. WINDS LOOK TO REMAIN FAIRLY MODEST FROM THE SOUTH EARLY IN THE WEEK WHILE LOW PRESSURE DEVELOPS OVER THE PLAINS. THIS LOW IS EXPECTED TO DEEPEN AND EVENTUALLY TRACK TOWARD THE WESTERN LAKES BY MID-WEEK. THE EXACT TRACK REMAINS A LITTLE UNCERTAIN AT THIS POINT...THOUGH MOST MODEL GUIDANCE BRINGS THE LOW ACROSS IOWA INTO WISCONSIN OR NORTHERN ILLINOIS ON WEDNESDAY...BEFORE SOLUTIONS DIVERGE. IN EITHER CASE...WINDS ARE EXPECTED TO BACK SOUTHEAST-EAST AND INCREASE AS THE GRADIENT TIGHTENS UP IN ADVANCE OF THE LOW TUESDAY NIGHT INTO EARLY WEDNESDAY. NORTH-NORTHWEST WINDS AROUND 20 KT THIS MORNING PRODUCING 4-5 FOOTERS AT BUOYS ALONG THE SOUTH/SOUTHEAST SHORE. SMALL CRAFT ADVISORY WILL REMAIN IN EFFECT THROUGH THIS AFTERNOON FOR THE INDIANA NEARSHORE WATERS. WINDS DIMINISH AND BACK QUICKLY TOWARD EVENING WHICH SHOULD ALLOW WAVES TO SUBSIDE FAIRLY QUICKLY BY EVENING. RATZER && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...BEACH HAZARDS STATEMENT...INZ001-INZ002 UNTIL 7 PM SATURDAY. LM...SMALL CRAFT ADVISORY...INDIANA NEARSHORE WATERS UNTIL 7 PM SATURDAY. && $$ VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE) FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT: WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.CHICAGO.GOV WWW.TWITTER.COM/NWSCHICAGO WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion NATIONAL WEATHER SERVICE LINCOLN IL 1055 AM CDT Sat Sep 6 2014 .UPDATE... ISSUED AT 1051 AM CDT SAT SEP 6 2014 Persistent stratus deck behind the frontal boundary that passed through last night very slow to clear. Concerned for the high temps in the far SE. In the last couple hours, the clouds have started to progress slightly to the SE and less concerned with the highs in the NW, but still have a ways to go with temps lingering in the 60s through mid morning. Will only make slight adjustments in the NW...possibly a couple degrees in the SE. Some minor and sct showers remain in the far SE and see no reason to pull the mention, and will continue to adjust to trends. Updates out momentarily. && .SHORT TERM...(Today) ISSUED AT 259 AM CDT SAT SEP 6 2014 Despite passage of a cold front during the evening hours, scattered light showers persist across the southern two-thirds of the KILX CWA early this morning. NAM/GFS/ECMWF have all verified too far north with lingering precip field at 06z, while the latest HRRR seems to have the best handle on the current situation. Following the latest radar trends and HRRR solution, have maintained low chance PoPs along/south of I-70 into the early afternoon before showers gradually push further southward into the Ohio River Valley. Meanwhile further north, have gone with a dry forecast across the remainder of the CWA. Skies will start out mostly cloudy, followed by a steady clearing trend from north to south as the day progresses. Afternoon high temperatures will be quite a bit cooler than yesterday, with readings remaining in the lower to middle 70s. && .LONG TERM...(Tonight through Friday) ISSUED AT 259 AM CDT SAT SEP 6 2014 High pressure will build into the region tonight into Sunday, resulting in clear skies and cool temperatures. Light winds/dry airmass will allow excellent radiational cooling to take place tonight, with lows bottoming out in the lower to middle 50s. On the flip side, full sunshine acting on the dry airmass will help temperatures rebound nicely into the middle to upper 70s on Sunday. Once the upper trough responsible for the cool weather lifts into eastern Canada, an active zonal flow pattern will develop across the CONUS next week. Two distinct systems will track through this flow, bringing rain chances to central Illinois. The first is progged to track from the Northern Plains Sunday night into the southern Great Lakes by Tuesday morning. Models are developing showers/storms in advance of this feature Monday night as low-level jet focuses across northern Missouri/southern Iowa. Solutions vary as to how far east into the prevailing surface ridge axis precip will penetrate late Monday night into Tuesday. Given presence of very dry airmass initially and only weak upper support with the short-wave, will keep highest PoPs confined to the Illinois River Valley Monday night. Further east, will go with a dry forecast along/east of I-57. Will only mention low chance PoPs on Tuesday as nocturnal convection undergoes diurnal weakening further eastward into the dry airmass. Second stronger wave will approach Tuesday night into Wednesday, bringing a much better chance for widespread rain. Models are suggesting moisture from tropical system in the Pacific may get drawn into this feature, resulting in unseasonably high precipitable water values in excess of 2 inches. GFS/ECMWF/GEM all bring a hefty slug of precip into Illinois late Tuesday night into Wednesday accordingly: however, axis of heaviest precip still remains in question. Have boosted PoPs to likely across the northern two-thirds of the CWA Tuesday night and Wednesday. Initial QPF from WPC indicates the potential for 1 to 2 inches of rain across much of the area during this time, with the highest amounts across the Illinois River Valley. Once wave passes to the east, strong cold front will settle southward, taking the higher rain chances into the far southern CWA Wednesday night. After that, most model guidance is advertising a cooler/drier day on Thursday followed by a shot of even cooler air by the end of the week. Both the GFS and ECMWF show 850mb temps dropping to around 0c by next Saturday morning, potentially resulting in highs only in the middle to upper 60s and lows dipping into the 40s next weekend. && .AVIATION...(For the 12Z TAFS through 12Z Sunday morning) ISSUED AT 600 AM CDT SAT SEP 6 2014 Areas of MVFR and local IFR cigs will give way to VFR conditions later this morning across the entire area as high pressure builds in from the northwest. Band of stratus continues to edge slowly to the southeast this morning with a large area mid level clouds generally above 12000 feet remaining. The mid cloud band will also slowly pull away from the area later this morning into the early afternoon hours. Forecast soundings suggest cumulus to develop across the forecast area by early afternoon with bases of 3000-4000 feet which should dissipate by late afternoon. Surface winds will remain out of a northerly direction today with speeds in the 8 to 13 kt range. Tonight, as the large area of high pressure settles in, look for nearly calm winds to prevail. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...HJS SHORT TERM...BARNES LONG TERM...BARNES AVIATION...SMITH
AREA FORECAST DISCUSSION
NWS JACKSON KY
137 PM EDT SAT SEP 6 2014 .UPDATE... ISSUED AT 1148 AM EDT SAT SEP 6 2014 LATEST MESOANALYSIS SHOWS WEAK SURFACE CONVERGENCE ACROSS THE CENTRAL PART OF THE FORECAST AREA. THIS IS AHEAD OF THE APPROACHING COLD FRONT WHICH HAS MOVED INTO NORTHERN KY. SBCAPE IN EXCESS OF 2500 J/KG ALSO ACROSS THE CENTRAL PART OF THE FORECAST AREA. CURRENT THINKING IS THAT CONVECTION WILL INITIATE EARLY THIS AFTERNOON WHERE THE LOW LEVEL CONVERGENCE COINCIDES WITH THE GREATEST CAPE. THIS IDEA IS ALSO SUPPORTED BY THE 14Z HRRR. HAVE ADJUSTED NDFD AND ASSOCIATED FORECAST PRODUCTS ACCORDINGLY. THERE IS ALSO SOME RAIN OCCURRING BEHIND THE FRONT...AND THE 12Z NAM AND 14Z HRRR BRING PRECIPITATION INTO THE NORTHERN PART OF THE FORECAST AREA AS WELL...EVEN THOUGH THE INITIAL CONVECTIVE DEVELOPMENT THROUGH MID AFTERNOON SHOULD BE FOCUSED IN THE CENTRAL PART OF THE FORECAST AREA. ONCE SHOWERS AND THUNDERSTORMS DEVELOP THIS AFTERNOON CURRENT STORM MOTION FORECAST WILL RESULT IN MOVEMENT TO THE SOUTHEAST AT 10 TO 15 MPH. UPDATE ISSUED AT 953 AM EDT SAT SEP 6 2014 UPDATED HOURLY NDFD BASED ON LATEST OBSERVATIONAL AND MODEL TRENDS. HAVE LOWERED THUNDERSTORM CHANCES FOR THE NEXT COUPLE OF HOURS FOLLOWING THE LATEST HRRR AND SATELLITE AND RADAR TRENDS. LOCALLY DENSE FOG HAS LIFTED AND HAVE UPDATED ZFP TO REMOVE MENTION OF MORNING FOG. 12Z SOUNDINGS SHOWING PWS OF AROUND 1.6 INCHES SO LOCALLY HEAVY RAINS STILL LOOK POSSIBLE AS NOTED IN THE HWO. UPDATE ISSUED AT 730 AM EDT SAT SEP 6 2014 DID A QUICK UPDATE TO THE GRIDS TO REFLECT THE CURRENT RADAR OBSERVATIONS AND TRENDS WITH RESPECT TO POPS AND WX. THE LATEST HRRR DOESN/T REALLY GET THINGS GOING AROUND HERE UNTIL AFTER 18Z SO HAVE TRENDED TOWARD THAT IDEA. ALSO...FINE TUNED THE T/TD ONES PER THE OBS AND TRENDS. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 350 AM EDT SAT SEP 6 2014 07Z SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE MOVING THROUGH EASTERN CANADA WITH A TRAILING COLD FRONT RUNNING SOUTHWEST THROUGH THE OHIO VALLEY AND INTO SOUTHERN MISSOURI. THE REMAINS OF A SQUALL LINE HAS SETTLED JUST SOUTH OF THE OHIO RIVER...OUT AHEAD OF THE COLD FRONT. A FEW LINGERING SHOWERS REMAIN WITH THIS AS IT CONTINUES TO FADE OUT WITH ITS APPROACH TO THE JKL CWA. ON SATELLITE...MID AND HIGH LEVEL CLOUDS COVER THE OHIO VALLEY NORTH AND WEST OF THIS OUTFLOW BOUNDARY. HOWEVER...THE CLEARER SKIES TO THE SOUTH HAS ALLOWED AREAS OF FOG TO DEVELOP THROUGH EAST KENTUCKY WITH LOCALLY DENSE PATCHES IN THE VALLEYS. HIGH DEWPOINTS IN THE UPPER 60S AND LOWER 70S ARE PROVIDING A FLOOR TO THE COOLING THIS NIGHT WITH JUST A SMALL RIDGE AND VALLEY SPLIT EVIDENT WITH READINGS VARYING FROM LOWER 70S IN THE THERMAL BELT TO THE UPPER 60S IN THE LOW SPOTS. WINDS REMAIN LIGHT TO CALM THROUGH THE AREA. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM AS HEIGHTS FALL OVER THE OHIO VALLEY IN RESPONSE TO A BROAD TROUGH MOVING THROUGH THE NORTHEAST PORTION OF THE CONTINENT. THE ENERGY STREAM ASSOCIATED WITH THIS MOVES QUICKLY INTO THE SOUTHERN OHIO VALLEY TODAY...BUT THEN LINGERS OVERHEAD THROUGH THE WEEKEND WITH A BIT OF A RESURGENCE LATER SUNDAY. GIVEN THE GOOD MODEL AGREEMENT... FOR WEATHER SPECIFICS HAVE FAVORED A BLEND OF THE HRRR AND NAM12 THROUGH THE FIRST HALF OF THE SHORT TERM FOLLOWED BY A MIX OF THE NAM AND LATEST ECMWF SOLUTIONS. SENSIBLE WEATHER WILL FEATURE AREAS OF FOG...LOCALLY DENSE...BURNING OFF EARLY THIS MORNING. THIS WILL BE FOLLOWED BY THE ARRIVAL OF SHOWERS AND THUNDERSTORMS BY MID AFTERNOON FROM NORTH TO SOUTH AS A COLD FRONT PRESSES SOUTH INTO THE AREA. PWS WITH THIS CONVECTION WILL BE MODERATELY HIGH WHILE STORM MOTION STARTS TO SPEED UP AS THE DAY WEARS ON. THIS SHOULD LIMIT THE RISK FOR FLASH FLOODING WHEN COMPARED TO THE PAST SEVERAL DAYS. HOWEVER...A LOCALIZED THREAT FOR HEAVY RAIN WILL REMAIN SHOULD TRAINING DEVELOP IN ANY PARTICULARLY LOCATION. THE THUNDER IS ANTICIPATED TO FADE FROM THE CONVECTION LATER TONIGHT AS THE FRONT SINKS SOUTH OF AREA LEAVING JUST A FEW LIGHT SHOWERS TRAILING BEHIND. FOR SUNDAY...THE NEARBY FRONT MAY CAUSE A SHOWER OR TWO TO POP UP OVER FAR SOUTHEAST KENTUCKY WHILE THE BOUNDARY SLOWS IN RESPONSE TO A BUCKLE IN THE MID LEVEL FLOW AND A DEVELOPING WAVE AT THE SFC ALONG THE GEORGIA COAST. THE WARMTH AND STICKY HUMIDITY WILL LEAVE THE AREA...AT LEAST FOR A COUPLE OF DAYS...ONCE THE FRONT MOVES THROUGH MEANING THAT SUNDAY WILL BE A MUCH MORE COMFORTABLE DAY THAN TODAY AND ALSO PROVIDE A HINT OF THE FALL-LIKE WEATHER THAT COULD ARRIVE IN EARNEST LATER IN THE WEEK. FOR TEMPERATURES...DEWPOINTS...AND WINDS...USED THE CONSSHORT FOR THE FIRST 24 HOURS AND THEN THE SUPERBLEND THROUGH SUNDAY. DID MAKE SOME MINOR ADJUSTMENTS FOR TERRAIN DIFFERENCES WITH TEMPS TONIGHT. AS FOR POPS ENDED UP ON THE HIGH SIDE OF MOS GUIDANCE TODAY...COUNTING ON MOST OF THE AREA MEASURING AS THIS FRONT MOVES THROUGH GIVEN THE FAIRLY HIGH MOISTURE CONTENT IN PLACE. WAS SIMILAR TO THE GUIDANCE TONIGHT AND SUNDAY...LIMITING THE CHANCE POPS TO THE FAR SOUTHEAST. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 335 AM EDT SAT SEP 6 2014 THE MODELS CONTINUE TO BE IN GOOD AGREEMENT IN REGARDS TO A SIGNIFICANT PATTERN CHANGE FOR THE END OF NEXT WEEK...WITH A MAJOR COOL DOWN IN STORE. HOWEVER...THE MODELS DIFFER IN HOW THEY HANDLE THE EVOLUTION OF WEATHER SYSTEMS THAT WILL BRING SHOWERS AND STORMS TO EASTERN KENTUCKY DURING THE UPCOMING WORK WEEK. THE PERIOD WILL START OUT WARM AND DRY AS HIGH PRESSURE SUNDAY NIGHT THROUGH TUESDAY. THERE IS A POSSIBILITY OF SCATTERED SHOWERS AND STORMS FORMING BENEATH THE RIDGE ON MONDAY...AS MOISTURE OFF THE GULF OF MEXICO GETS DRAWN INTO THE AREA BY A WEAK AREA OF LOW PRESSURE THAT IS PROGGED TO PASS ACROSS THE TENNESSEE VALLEY. THE ECMWF WAS SLOWER AND WETTER THAN THE GFS FROM WEDNESDAY ONWARD. BOTH MODELS HAVE A COLD FRONT MOVING ACROSS THE OHIO AND TENNESSEE VALLEY REGIONS WEDNESDAY THROUGH FRIDAY...WITH SCATTERED SHOWERS AND STORMS FORMING IN THE VICINITY OF THE BOUNDARY. WITH UNCERTAINTY BETWEEN THE MODELS...DECIDED TO USE A BLEND OF THE ECMWF AND GFS MODELS...WITH A SLIGHT BIAS TOWARD TO NORMALLY MORE RELIABLE ECMWF SOLUTION. THE BEST CHANCES FOR RAIN WILL COME FROM LATE WEDNESDAY NIGHT THROUGH THURSDAY EVENING DURING FRONTAL PASSAGE. TEMPERATURES THE FIRST FEW DAYS OF THE PERIOD LOOK TO BE AT OR SLIGHT BELOW NORMAL...DUE TO THE INFLUENCE OF NORTHERLY FLOW...CLOUD COVER...AND PRECIPITATION ASSOCIATED WITH AN AREA OF LOW PRESSURE THAT IS EXPECTED TO PASS THROUGH THE TENNESSEE VALLEY ON MONDAY. HIGHS ON MONDAY ARE EXPECTED TO TOP OUT AROUND 80...WITH READINGS MAXING OUT IN THE LOW TO MID 80S ON TUESDAY AND WEDNESDAY. THE BIG PATTERN CHANGE LOOKS LIKE IT WILL TAKE PLACE FROM THURSDAY ONWARD...AS A COOL CANADIAN AIR MASS SETTLES OVER THE REGION BEHIND A DEPARTING AND VERY POTENT COLD FRONT. HIGHS ON FRIDAY MIGHT ONLY TOP OUT IN THE LOW TO MID 70S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 136 PM EDT SAT SEP 6 2014 A BROKEN LINE OF THUNDERSTORMS AHEAD OF AN APPROACHING COLD FRONT WILL AFFECT ALL TAF SITES THIS AFTERNOON. THE THUNDERSTORMS WILL EXIT THE FORECAST AREA BY 00Z THIS EVENING. OUTSIDE OF THUNDERSTORMS VFR CONDITIONS WILL PREVAIL ACROSS THE AREA...BUT THERE WILL BE LOCAL SPOTS WITH MVFR CEILINGS. AFTER THE COLD FRONT PASSAGE EXTENSIVE LOW CLOUDINESS WILL SPREAD ACROSS THE AREA TONIGHT...WITH WIDESPREAD MVFR CEILINGS EXPECTED TO PERSIST INTO THE DAY ON SUNDAY. VFR CONDITIONS SHOULD RETURN LATE SUNDAY AFTERNOON...AS CLOUDS LIFT AND BEGIN TO DECREASE IN COVERAGE. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SBH SHORT TERM...GREIF LONG TERM...AR AVIATION...SBH
AREA FORECAST DISCUSSION
NWS GRAY ME
652 PM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL PUSH OFFSHORE THIS EVENING. HIGH PRESSURE WILL BUILD IN FROM THE WEST SUNDAY AND WILL SHIFT INTO THE MARITIMES ON MONDAY. HIGH PRESSURE WILL HOLD OFF THE COAST THROUGH TUESDAY. A WARM FRONT WILL LIFT NORTH THROUGH THE REGION ON WEDNESDAY. A COLD FRONT WILL APPROACH FROM THE WEST ON THURSDAY AND WILL SLOWLY CROSS THE AREA ON FRIDAY. && .NEAR TERM /TONIGHT/... 7PM UPDATE... HAVE UPDATED TO DROP THE SEVERE THUNDERSTORM WATCH AS THE FRONT AND THUNDERSTORMS ALONG IT HAS MADE IT TO THE COAST. SEVERE THREAT FOR TODAY IS OVER. RAIN CHANCES ARE ALSO GREATLY REDUCED. COOLER AND DRIER AIR IS MOVING IN SHARPLY BEHIND THIS FRONT. NO OTHER CHANGES MADE TO THE FORECAST AT THIS TIME. PREVIOUS DISCUSSION... DEEP MOISTURE AND INCREASED INSTABILITY WITH HIGH CAPE AND PRECIPITABLE WATER VALUES WILL COMBINE WITH AN APPROACHING FRONT TO TRIGGER MORE SCATTERED SHOWERS AND THUNDERSTORMS INTO THIS EVENING. A FEW OF THESE STORMS MAY CONTAIN DAMAGING WIND GUSTS AND LOCALLY VERY HEAVY RAINFALL INTO THIS EVENING. LATEST HRRR MODEL RUN...WHICH HAS HANDLED THIS EVENT RELATIVELY WELL...CONTINUES TO SHOW THE CONVECTION ALONG THE IMMEDIATE COAST TIL AROUND 23Z. AFTER THE COLD FRONTAL PASSAGE...SKIES WILL BEGIN TO CLEAR AND CONDITIONS WILL BECOME MORE COMFORTABLE AS DEW POINT VALUES FALL. THERE WILL BE SOME INLAND FOG DEVELOPING LATE AT NIGHT OVER THE USUAL SUSPECT LOCATIONS INCLUDING THE CONNECTICUT RIVER VALLEY. && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... ALL MODELS IN AGREEMENT DEPICTING HIGH PRESSURE WILL BEGIN TO BUILD INTO THE REGION SUNDAY WITH CLEARING SKIES OVER THE COAST EARLY IN THE MORNING. NORTHWEST...OFFSHORE WINDS WILL ALLOW FOR MILD TEMPERATURES ALONG THE COAST. WITH COLD AIR ADVECTION CONTINUING SUNDAY NIGHT...EXPECT A FEW READINGS IN THE UPPER 30S IN THE MOUNTAINS. THERE MAY BE SOME SCATTERED FROST IN THE MOUNTAINS...IN THE COLDEST VALLEYS. && .LONG TERM /MONDAY THROUGH SATURDAY/... HIGH PRESSURE WILL CREST OVER THE REGION EARLY MONDAY BEFORE SHIFTING EAST INTO THE MARITIMES. EXPECT MOSTLY SUNNY SKIES BUT TEMPERATURES WILL AVERAGE OUT BELOW NORMAL WITH HIGHS ONLY IN THE 60S. MOSTLY CLEAR MONDAY NIGHT WITH LOWS IN THE MID 40S TO LOWER 50S. MOSTLY CLEAR AND QUIET WEATHER CONTINUES ON TUESDAY AS HIGH PRESSURE REMAINS ANCHORED TO THE EAST. ONCE AGAIN TEMPERATURES WILL AVERAGE OUT BELOW NORMAL WITH HIGHS IN THE 60S TO NEAR 70. WARM FRONT SETTING UP TO THE NORTHWEST OF THE FORECAST AREA ON WEDNESDAY WILL BRING A FEW CLOUDS TO NORTHERN ZONES BUT EXPECT ANY ASSOCIATED PRECIPITATION TO REMAIN WELL WEST OF THE FORECAST AREA. REMAINDER OF THE REGION WILL SEE A MOSTLY SUNNY DAY WITH MODERATING TEMPERATURES. EXPECT MUCH OF THE REGION TO TOP OUT IN THE LOWER TO MID 70S. WARM FRONT WILL STALL ACROSS NORTHERN ZONES WEDNESDAY NIGHT BEFORE LIFTING NORTHWARD ON THURSDAY. MAY SEE SOME SHOWERS IN NORTHERN ZONES AFTER MIDNIGHT AS STRONGER OVER-RUNNING SHIFTS IN FROM THE WEST. REMAINDER OF THE FORECAST AREA WILL SEE INCREASING CLOUDS. OVER-RUNNING PRECIPITATION WILL OVER-SPREAD THE REGION ON THURSDAY. AN OCCLUDED FRONT PUSHING IN FROM THE WEST MAY BRING SOME LATE DAY CONVECTION TO WESTERN ZONES AND MAY CONTINUE INTO THURSDAY NIGHT AS THE FRONT SLOWLY PUSHES EASTWARD. FRONT WILL STALL ACROSS THE REGION BY FRIDAY MORNING AND WILL BE THE FOCUS FOR MORE RAIN AS A STRONG SHORTWAVE SWINGS IN FROM THE WEST. THIS WILL FINALLY SWEEP THE FRONT OFFSHORE BY LATE IN THE DAY. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR THE WEEKEND WITH ANOTHER SHOT OF UNSEASONABLY COOL WEATHER. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... SHORT TERM...LOCAL IFR OR LIFR CONDITIONS IN CONVECTION THIS EVENING WITH LOCALLY STRONG WIND GUSTS AND IN PATCHY FOG LATE. LONG TERM...VFR MONDAY THROUGH WEDNESDAY. MVFR/IFR CEILINGS/VISIBILITY THURSDAY. && .MARINE... SHORT TERM...SCA FOR WINDS/SEAS THROUGH THIS EVENING FOR THE OUTER COASTAL WATERS. LONG TERM...NO PROBLEMS NOTED. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT SUNDAY FOR ANZ150-152-154. && $$ NEAR TERM UPDATE...KIMBLE
AREA FORECAST DISCUSSION
NWS GRAY ME
513 PM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL PUSH OFFSHORE THIS EVENING. HIGH PRESSURE WILL BUILD IN FROM THE WEST SUNDAY AND WILL SHIFT INTO THE MARITIMES ON MONDAY. HIGH PRESSURE WILL HOLD OFF THE COAST THROUGH TUESDAY. A WARM FRONT WILL LIFT NORTH THROUGH THE REGION ON WEDNESDAY. A COLD FRONT WILL APPROACH FROM THE WEST ON THURSDAY AND WILL SLOWLY CROSS THE AREA ON FRIDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... *** SEVERE THUNDERSTORM WATCH BOX OUR TIL 9 PM FOR ALL AREAS EXCEPT THE NORTHERN MOUNTAINS *** DEEP MOISTURE AND INCREASED INSTABILITY WITH HIGH CAPE AND PRECIPITABLE WATER VALUES WILL COMBINE WITH AN APPROACHING FRONT TO TRIGGER MORE SCATTERED SHOWERS AND THUNDERSTORMS INTO THIS EVENING. A FEW OF THESE STORMS MAY CONTAIN DAMAGING WIND GUSTS AND LOCALLY VERY HEAVY RAINFALL INTO THIS EVENING. LATEST HRRR MODEL RUN...WHICH HAS HANDLED THIS EVENT RELATIVELY WELL...CONTINUES TO SHOW THE CONVECTION ALONG THE IMMEDIATE COAST TIL AROUND 23Z. AFTER THE COLD FRONTAL PASSAGE...SKIES WILL BEGIN TO CLEAR AND CONDITIONS WILL BECOME MORE COMFORTABLE AS DEW POINT VALUES FALL. THERE WILL BE SOME INLAND FOG DEVELOPING LATE AT NIGHT OVER THE USUAL SUSPECT LOCATIONS INCLUDING THE CT RIVER VALLEY. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... ALL MODELS IN AGREEMENT DEPICTING HIGH PRESSURE WILL BEGIN TO BUILD INTO THE REGION SUNDAY WITH CLEARING SKIES OVER THE COAST EARLY IN THE MORNING. NORTHWEST...OFFSHORE WINDS WILL ALLOW FOR MILD TEMPS ALONG THE COAST. WITH COLD AIR ADVECTION CONTINUING SUNDAY NIGHT...EXPECT A FEW READINGS IN THE UPPER 30S IN THE MOUNTAINS. THERE MAY BE SOME SCATTERED FROST IN THE MOUNTAINS...IN THE COLDEST VALLEYS. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... HIGH PRESSURE WILL CREST OVER THE REGION EARLY MONDAY BEFORE SHIFTING EAST INTO THE MARITIMES. EXPECT MOSTLY SUNNY SKIES BUT TEMPS WILL AVERAGE OUT BELOW NORMAL WITH HIGHS ONLY IN THE 60S. MOSTLY CLEAR MONDAY NIGHT WITH LOWS IN THE MID 40S TO LOWER 50S. MOSTLY CLEAR AND QUIET WEATHER CONTINUES ON TUESDAY AS HIGH PRESSURE REMAINS ANCHORED TO THE EAST. ONCE AGAIN TEMPS WILL AVERAGE OUT BELOW NORMAL WITH HIGHS IN THE 60S TO NEAR 70. WARM FRONT SETTING UP TO THE NORTHWEST OF THE FORECAST AREA ON WEDNESDAY WILL BRING A FEW CLOUDS TO NORTHERN ZONES BUT EXPECT ANY ASSOCIATED PRECIP TO REMAIN WELL WEST OF THE FORECAST AREA. REMAINDER OF THE REGION WILL SEE A MOSTLY SUNNY DAY WITH MODERATING TEMPS. EXPECT MUCH OF THE REGION TO TOP OUT IN THE LOWER TO MID 70S. WARM FRONT WILL STALL ACROSS NORTHERN ZONES WEDNESDAY NIGHT BEFORE LIFTING NORTHWARD ON THURSDAY. MAY SEE SOME SHOWERS IN NORTHERN ZONES AFTER MIDNIGHT AS STRONGER OVER-RUNNING SHIFTS IN FROM THE WEST. REMAINDER OF THE FORECAST AREA WILL SEE INCREASING CLOUDS. OVER-RUNNING PRECIP WILL OVER-SPREAD THE REGION ON THURSDAY. AN OCCLUDED FRONT PUSHING IN FROM THE WEST MAY BRING SOME LATE DAY CONVECTION TO WESTERN ZONES AND MAY CONTINUE INTO THURSDAY NIGHT AS THE FRONT SLOWLY PUSHES EASTWARD. FRONT WILL STALL ACROSS THE REGION BY FRIDAY MORNING AND WILL BE THE FOCUS FOR MORE RAIN AS A STRONG SHORTWAVE SWINGS IN FROM THE WEST. THIS WILL FINALLY SWEEP THE FRONT OFFSHORE BY LATE IN THE DAY. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR THE WEEKEND WITH ANOTHER SHOT OF UNSEASONABLY COOL WEATHER. && .AVIATION /21Z SATURDAY THROUGH THURSDAY/... SHORT TERM...LOCAL IFR OR LIFR CONDITIONS IN CONVECTION THIS EVENING WITH LOCALLY STRONG WIND GUSTS AND IN PATCHY FOG LATE. LONG TERM...VFR MONDAY THROUGH WEDNESDAY. MVFR/IFR CEILINGS/VSBY THURSDAY. && .MARINE... SHORT TERM...SCA FOR WINDS/SEAS THROUGH THIS EVENING FOR THE OUTER COASTAL WATERS. LONG TERM...NO PROBLEMS NOTED. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT SUNDAY FOR ANZ150-152-154. && $$ JC
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
430 PM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL PUSH OFFSHORE THIS EVENING. HIGH PRESSURE WILL BUILD IN FROM THE WEST SUNDAY AND WILL SHIFT INTO THE MARITIMES ON MONDAY. HIGH PRESSURE WILL HOLD OFF THE COAST THROUGH TUESDAY. A WARM FRONT WILL LIFT NORTH THROUGH THE REGION ON WEDNESDAY. A COLD FRONT WILL APPROACH FROM THE WEST ON THURSDAY AND WILL SLOWLY CROSS THE AREA ON FRIDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... *** SEVERE THUNDERSTORM WATCH BOX OUR TIL 9 PM FOR ALL AREAS EXCEPT THE NORTHERN MOUNTAINS *** DEEP MOISTURE AND INCREASED INSTABILITY WITH HIGH CAPE AND PRECIPITABLE WATER VALUES WILL COMBINE WITH AN APPROACHING FRONT TO TRIGGER MORE SCATTERED SHOWERS AND THUNDERSTORMS INTO THIS EVENING. A FEW OF THESE STORMS MAY CONTAIN DAMAGING WIND GUSTS AND LOCALLY VERY HEAVY RAINFALL INTO THIS EVENING. LATEST HRRR MODEL RUN...WHICH HAS HANDLED THIS EVENT RELATIVELY WELL...CONTINUES TO SHOW THE CONVECTION ALONG THE IMMEDIATE COAST TIL AROUND 23Z. AFTER THE COLD FRONTAL PASSAGE...SKIES WILL BEGIN TO CLEAR AND CONDITIONS WILL BECOME MORE COMFORTABLE AS DEW POINT VALUES FALL. THERE WILL BE SOME INLAND FOG DEVELOPING LATE AT NIGHT OVER THE USUAL SUSPECT LOCATIONS INCLUDING THE CT RIVER VALLEY. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/... ALL MODELS IN AGREEMENT DEPICTING HIGH PRESSURE WILL BEGIN TO BUILD INTO THE REGION SUNDAY WITH CLEARING SKIES OVER THE COAST EARLY IN THE MORNING. NORTHWEST...OFFSHORE WINDS WILL ALLOW FOR MILD TEMPS ALONG THE COAST. WITH COLD AIR ADVECTION CONTINUING SUNDAY NIGHT...EXPECT A FEW READINGS IN THE UPPER 30S IN THE MOUNTAINS. THERE MAY BE SOME SCATTERED FROST IN THE MOUNTAINS...IN THE COLDEST VALLEYS. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... HIGH PRESSURE WILL CREST OVER THE REGION EARLY MONDAY BEFORE SHIFTING EAST INTO THE MARITIMES. EXPECT MOSTLY SUNNY SKIES BUT TEMPS WILL AVERAGE OUT BELOW NORMAL WITH HIGHS ONLY IN THE 60S. MOSTLY CLEAR MONDAY NIGHT WITH LOWS IN THE MID 40S TO LOWER 50S. MOSTLY CLEAR AND QUIET WEATHER CONTINUES ON TUESDAY AS HIGH PRESSURE REMAINS ANCHORED TO THE EAST. ONCE AGAIN TEMPS WILL AVERAGE OUT BELOW NORMAL WITH HIGHS IN THE 60S TO NEAR 70. WARM FRONT SETTING UP TO THE NORTHWEST OF THE FORECAST AREA ON WEDNESDAY WILL BRING A FEW CLOUDS TO NORTHERN ZONES BUT EXPECT ANY ASSOCIATED PRECIP TO REMAIN WELL WEST OF THE FORECAST AREA. REMAINDER OF THE REGION WILL SEE A MOSTLY SUNNY DAY WITH MODERATING TEMPS. EXPECT MUCH OF THE REGION TO TOP OUT IN THE LOWER TO MID 70S. WARM FRONT WILL STALL ACROSS NORTHERN ZONES WEDNESDAY NIGHT BEFORE LIFTING NORTHWARD ON THURSDAY. MAY SEE SOME SHOWERS IN NORTHERN ZONES AFTER MIDNIGHT AS STRONGER OVER-RUNNING SHIFTS IN FROM THE WEST. REMAINDER OF THE FORECAST AREA WILL SEE INCREASING CLOUDS. OVER-RUNNING PRECIP WILL OVER-SPREAD THE REGION ON THURSDAY. AN OCCLUDED FRONT PUSHING IN FROM THE WEST MAY BRING SOME LATE DAY CONVECTION TO WESTERN ZONES AND MAY CONTINUE INTO THURSDAY NIGHT AS THE FRONT SLOWLY PUSHES EASTWARD. FRONT WILL STALL ACROSS THE REGION BY FRIDAY MORNING AND WILL BE THE FOCUS FOR MORE RAIN AS A STRONG SHORTWAVE SWINGS IN FROM THE WEST. THIS WILL FINALLY SWEEP THE FRONT OFFSHORE BY LATE IN THE DAY. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR THE WEEKEND WITH ANOTHER SHOT OF UNSEASONABLY COOL WEATHER. && .AVIATION /21Z SATURDAY THROUGH THURSDAY/... SHORT TERM...LOCAL IFR OR LIFR CONDITIONS IN CONVECTION THIS EVENING WITH LOCALLY STRONG WIND GUSTS AND IN PATCHY FOG LATE. LONG TERM...VFR MONDAY THROUGH WEDNESDAY. MVFR/IFR CEILINGS/VSBY THURSDAY. && .MARINE... SHORT TERM...SCA FOR WINDS/SEAS THROUGH THIS EVENING FOR THE OUTER COASTAL WATERS. LONG TERM...NO PROBLEMS NOTED. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT SUNDAY FOR ANZ150-152-154. && $$ JC
AREA FORECAST DISCUSSION
NWS GRAY ME
131 PM EDT SAT SEP 6 2014 .SYNOPSIS... THE RETURN FLOW AROUND HIGH PRESSURE HAS INTRODUCED A VERY WARM AND HUMID AIR MASS TO THE REGION. A COLD FRONT WILL CROSS THE REGION TODAY ACCOMPANIED BY SHOWERS AND THUNDERSTORMS. SOME THUNDERSTORMS MAY PRODUCE STRONG GUSTY WINDS...FREQUENT LIGHTNING...AND TORRENTIAL DOWNPOURS WITH LOCALIZED FLOODING. HIGH PRESSURE AND DRY AIR FOLLOWS THE FRONT SUNDAY THROUGH TUESDAY. THE NEXT DISTURBANCE WITH UNSETTLED WEATHER SHOULD ARRIVE BY THE MIDDLE OF NEXT WEEK. THE UNSETTLED WEATHER IS EXPECTED TO CONTINUE THROUGH THE REMAINDER OF THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE... ***SEVERE THUNDERSTORM WATCH #497 NOW IN EFFECT TIL 9 PM*** HAVE UPDATED THE GRIDS BASED ON CURRENT CONDITIONS AS WELL AS LATEST MESOSCALE MODEL DATA. LATEST HRRR CONTINUES TO SHOW THE HIGHEST DEW POINTS AND THE GREATEST CHANCE FOR SEVERE WEATHER TO BE OVER SOUTHERN NEW HAMPSHIRE AND SOUTHWEST MAINE. WE CURRENTLY REMAIN IN A SLIGHT RISK FOR SEVERE WEATHER TODAY. WILL CONTINUE THE ENHANCED WORDING...WITH THE PRIMARY THREAT BEING DAMAGING WIND GUSTS IN SEVERE STORMS. AN ISOLATED TORNADO IS POSSIBLE AS WELL...WITH STRONG WIND FIELDS AND SIGNIFICANT SHEAR. HAVE ADJUSTED DEW POINT AND CLOUD GRIDS AS WELL BASED ON CURRENT SATELLITE IMAGERY...SURFACE OBSERVATIONS AND SOUNDING ANALYSIS. KEY WILL BE IF DRY AIR MIXES DOWN FROM ABOVE AND LOWERS OUR DEW POINTS OR NOT. MOST LIKELY AREA TO HAVE DEW POINTS NEAR 70 DEGREES WILL BE SOUTHERN NEW HAMPSHIRE AND YORK COUNTY IN MAINE. PREV DISC... HAVE UPDATED THE FORECAST SLIGHTLY THIS MORNING TO INCORPORATE LATEST TRENDS IN OBSERVATIONAL DATA. SHOULD SEE PLENTY OF SUN THIS MORNING WHICH SHOULD LEAD TO QUICK INSOLATIONAL HEATING. FORECAST FOR THUNDERSTORMS REMAINS THE SAME FOR THIS AFTERNOON. PREVIOUSLY... A WARM AND HUMID AIR MASS HAS OVERSPREAD THE REGION AS OF EARLY THIS SATURDAY MORNING...AS EVIDENCED BY TEMPERATURES STILL IN THE 70S WITH DEWPOINTS WELL INTO THE 60S AS OF 3 AM. A COLD FRONT IS EXPECTED TO CROSS THE AREA TODAY AND THIS SHOULD AID IN THE DEVELOPMENT OF SHOWERS AND THUNDERSTORMS. THE MAIN CONCERN REVOLVES AROUND STORM COVERAGE...TIMING...AND SEVERITY. AS A SHORT WAVE TROUGH APPROACHES FROM THE NW AND CONTINUES TO INDUCE HEIGHT FALLS...A COLD FRONT AND ASSOCIATED SFC CONVERGENCE SHOULD INITIATE THUNDERSTORMS ACROSS THE INTERIOR AROUND MIDDAY. STRONG SFC HEATING IS EXPECTED OUT AHEAD OF THE THUNDERSTORM ACTIVITY WITH HIGHS IN THE MID TO UPPER 80S PROGGED ON THE COASTAL PLAIN. A FEW LOCATIONS MAY EVEN TOUCH 90 FROM INTERIOR ROCKINGHAM COUNTY NORTHWARD INTO INTERIOR YORK AND CUMBERLAND COUNTIES. THIS COMBINED WITH DEWPOINT VALUES IN THE UPPER 60S TO AROUND 70 SHOULD RESULT IN MODERATE SBCAPE BY EARLY AFTERNOON WITH VALUES IN EXCESS OF 2000 J/KG. THEREFORE...PLENTY OF INSTABILITY IS EXPECTED TO BE PRESENT TO SUPPORT SVR STORMS. HOWEVER... THERE ARE SOME NEGATIVES...SUCH AS GRADUALLY WEAKENING MID LEVEL LAPSE RATES AS THE DAY PROGRESSES. ALSO...THE BEST DEEP LAYER SHEAR AND UPPER SUPPORT IS EXPECTED TO LAG BEHIND THE COLD FRONT. IN ADDITION...GOOD MIXING TO AROUND 850 MB IS EXPECTED TODAY. THIS WILL PROBABLY RESULT IN FALLING DEWPOINTS THIS AFTERNOON IN SOME AREAS...AND THIS WOULD EAT AWAY AT CAPE VALUES. ANOTHER ISSUE MAY BE THAT A PREFRONTAL TROF THAT IS EXPECTED TO DEVELOP ON THE COASTAL PLAIN EARLY THIS AFTERNOON COULD MOVE OFFSHORE TOO EARLY. THIS WOULD LOWER DEWPOINTS ACROSS THE AREA AND WEAKEN SFC CONVERGENCE. NEVERTHELESS...WE EXPECT AT LEAST A COUPLE OF SEVERE STORMS IN THE FORM OF ORGANIZED MULTICELL CLUSTERS AND LINE SEGMENTS WHICH MAY EVENTUALLY FORM A MORE SOLID LINE OF STORMS AS THEY APPROACH THE COAST. THE MAIN THREAT LOOK TO BE DAMAGING WINDS. TORRENTIAL DOWNPOURS ARE EXPECTED IN STORMS WITH THE ATTENDANT LOW RISK OF ISOLD FLASH FLOODING IN AREAS WHERE STORMS TRAIN IN THE HIGH PWAT AIR MASS. A NON-ZERO TORNADO THREAT MAY EXIST TODAY IN THE VICINITY OF MESOSCALE BOUNDARIES IF BRIEF SUPERCELL STRUCTURES CAN DEVELOP. AREAS OF LOCALLY BACKED WINDS TODAY WOULD BE SUPPORTIVE OF FAIRLY SIZABLE LOW LEVEL HODOGRAPHS GIVEN THE RELATIVELY STRONG SWLY WINDS EXPECTED IN THE 0-2 KM LAYER. THIS IS CONDITIONAL APON FAVRORABLE MOISTURE PROFILES THIS AFTERNOON...IE...IF WE DON/T MIX OUT THE RICH LOW LEVEL MOISTURE DUE TO MIXING OR A DEPARTING PREFRONTAL TROF TOO EARLY. CAPPED POPS AT LIKELY TODAY BECAUSE I/M NOT SO SURE THAT EVERYONE WILL SEE A STORM. THE MODELS SEEMED TO HAVE BACKED OFF ON COVERAGE A LITTLE BIT...PROBABLY DUE TO THE NEGATIVE FACTORS OUTLINED ABOVE. HIGHEST POPS HAVE BEEN PLACED BETWEEN 19Z AND 23Z. SFC WINDS LOOK TO BECOME GUSTY TODAY OUTSIDE OF ANY CONVECTION...POSSIBLY TO AROUND 25 MPH. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... SHOWERS AND STORMS WILL SWEEP OFFSHORE EARLY THIS EVENING. CLEARING SHOULD OCCUR TONIGHT ASIDE FROM LEFTOVER STRATUS AND FOG. SUNDAY SHOULD BE A REALLY NICE DAY...WARM AND MUCH DRIER. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... MODELS ARE IN A LITTLE BETTER AGREEMENT THIS MORNING FOR THE LONG TERM PERIOD. HIGH PRESSURE WILL DOMINATE THE WEATHER FOR SUNDAY NIGHT THROUGH TUESDAY. TEMPERATURES SUNDAY NIGHT WILL DIP TO RATHER CHILLY LEVELS WITH SOME OF THE COLDER MOUNTAIN VALLEYS POSSIBLY SEEING SOME FROST. A WEAK SYSTEM WILL PASS SOUTH OF THE REGION TUESDAY AND TUESDAY NIGHT AND SPREAD CLOUDS INTO SOUTHERN AREAS WITH ONLY A SLIGHT CHANCE OF A SHOWER. FAIR WEATHER IS EXPECTED WEDNESDAY WITH THE WEAK SURFACE RIDGE REMAINING ACROSS THE REGION. LOW PRESSURE MOVING THROUGH SOUTHEASTERN CANADA THURSDAY AND THURSDAY NIGHT WILL DRAG A COLD FRONT ACROSS THE REGION WITH SHOWERS/TSTMS LIKELY DURING THE DAY. MODELS START TO DIVERGE A BIT WITH THIS SYSTEM...ADDING UNCERTAINTY TO THE FORECAST. THE FRONT SHOULD BE OFF THE COAST BY FRIDAY MORNING. A SECOND FRONT WILL APPROACH THE AREA SATURDAY WITH AN INCREASING CHANCE OF SHOWERS. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... SHORT TERM...SHOWERS AND THUNDERSTORMS ARE EXPECTED TODAY...MAINLY THIS AFTERNOON. THIS WOULD ALLOW FOR LOCAL IFR CONDITIONS. BETTER CONDITIONS ARE FORECAST LATER TONIGHT ALTHOUGH SOME STRATUS AND FOG MAY DEVELOP IN RIVER VALLEYS AND ALONG THE COAST...ESPECIALLY THIS EVENING BEFORE DRIER AIR ARRIVES. WALL TO WALL VFR EXPECTED SUNDAY. LONG TERM...MAINLY VFR CONDITIONS WITH IFR CONDITIONS POSSIBLE IN MORNING VALLEY FOG. && .MARINE... SHORT TERM...SCA FOR THE OUTER WATERS THROUGH THIS EVENING FOR MARGINAL SMALL CRAFT CONDITIONS. A FEW 25 KT GUSTS MAY OCCUR IN THE BAYS AS WELL...BUT CONFIDENCE IS LOW. THUNDERSTORMS WITH GUSTY WINDS ARE EXPECTED TO POSE A HAZARD LATE THIS AFTERNOON. LONG TERM...NO FLAGS THROUGH TUESDAY. SEAS MAY REACH SCA CRITERIA LATE TUE NIGHT. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT SUNDAY FOR ANZ150-152-154. && $$ JC
AREA FORECAST DISCUSSION
NWS CARIBOU ME
1246 PM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL CONTINUE MOVING SOUTHEAST ACROSS THE EAST CENTRAL AND DOWNEAST PORTIONS OF THE REGION THIS AFTERNOON. COOLER HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT SUNDAY INTO MONDAY. && .NEAR TERM /THROUGH TONIGHT/... 1242 PM UPDATE: POPS AND SKY GRIDS LOOK REASONABLE FROM THE LAST UPDATE...SO NO CHGS FOR THESE ELEMENTS THIS UPDATE. FCST HRLY TEMPS AND FCST AFTN HI TEMPS NEEDED TOP BE ADJUSTED BASED ON TRENDS FROM NOON OBSVD TEMPS. ORGNL DISC: SEVERE WEATHER STILL LOOKS TO BE A GOOD THREAT MAINLY FROM THE HOULTON-MILLINOCKET REGION DOWN THROUGH THE CENTRAL HIGHLANDS AND INTERIOR DOWNEAST. THE LATEST SURFACE ANALYSIS AT 06Z SHOWED THE COLD FRONT MOVING INTO QUEBEC W/AN AREA OF SHOWERS AND ISOLD TSTMS MOVING ACROSS NW MAINE TOWARD NE MAINE. LATEST MESO ANALYSIS SHOWED THE BEST INSTABILITY RESIDING IN THIS REGION AS SHOWN BY THE LIFTED INDEX OF -2 TO -4 RUNNING FROM QUEBEC THROUGH NW MAINE. FURTHER E, ATMOSPHERE IS MORE STABLE ATTM. THE HRRR 3KM AND THE NAM12 WERE DOING WELL W/PLACEMENT AND INSTABILITY. A LARGE LINE OF LIGHTNING STRIKES HAD EXTENDED FROM QUEBEC DOWN ACROSS NYS AND PA BUT HAVE SINCE DISSIPATED. THIS IS EXPECTED TO CHANGE LATER THIS MORNING INTO THE AFTERNOON THE FRONT CONTINUE TO PUSH E AND THE AIRMASS DESTABILIZES. THE LATEST RUNS OF THE NAM AND GFS CONTINUE TO SHOW THE HIGHEST THREAT FOR POSSIBLY SEVERE TSTMS W/EHI RUNNING FROM 1 TO 2 AND SB/MU CAPES OF 1200-2000 JOULES AND 0-6KM SHEAR OF 35-40 KTS. ANOTHER FACTOR TO CONSIDER WILL BE THE DIRECTIONAL SHEAR THROUGH 850MBS AND LCLS MAKING THEIR DECENT FROM 5K FT DOWN TO 2500 FT. IN ADDITION TO ALL THIS WILL BE VERY HIGH PWATS OF 1.7+ INCHES AND SWEAT INDEX OF 300+. ALL THIS WOULD SUGGEST THE POTENTIAL FOR DAMAGING WINDS AND VERY HEAVY RAINFALL. SOME ROTATION COULD BE SEEN IN THE STRONGER STORMS GIVEN THE TURNING IN THE LLVLS AND THE LOWER LCLS. KEPT THE ENHANCED WORDING FOR GUSTY WINDS AND HEAVY RAINFALL. THE WORDING MIGHT NEED TO BE BOOSTED TO INCLUDE DAMAGING WINDS IF THINGS HOLD W/THE UPDATE LATER THIS MORNING. TEMPERATURES WILL FALL BACK ACROSS NORTHERN MAINE AFTER 1 PM AS THE FRONT SLIDE THROUGH WHILE THE CENTRAL HIGHLANDS AND DOWNEAST WILL HAVE TIME TO HEAT UP W/AFTERNOON TEMPERATURES HITTING IN THE LOWER 80S. SPC HAS KEPT THE SLIGHT RISK FOR SEVERE WEATHER FOR OUR REGION IN PLACE FOR TODAY. THE COLD FRONT IS FORECAST TO SLIDE INTO THE COASTAL WATERS THIS EVENING W/PARTIAL CLEARING TAKING PLACE AND A DRAMATIC COOL DOWN. WE ARE TALKING 10-15 DEGREES COOLER THAN WHAT WE HAVE SEEN THAT LAST FEW MORNINGS. SOME OF THE SITES BACK TO THE W AND NW COULD DROP BACK INTO THE UPPER 30S BY EARLY MONDAY MORNING. && .SHORT TERM /SUNDAY THROUGH MONDAY/... AT THE START OF THE NEAR TERM PERIOD. A COLD FRONT WILL BE EXTENDED ALONG THE COAST OF MAINE. HIGHER PRESSURE WILL BEGIN TO BUILD INTO THE AREA. COOLER DRIER AIR WILL MOVE INTO THE AREA WITH THE HIGH. DAY TIME TEMPS SUNDAY IN THE MID 60S AND LOWER 60S MONDAY. OVERNIGHT LOWS IN THE LOWER 40S. THE HIGH PRESSURE RIDGE WILL DOMINATE THE WEATHER THROUGH THE NEAR TERM PERIOD OF THE FORECAST. LOADED A BLEND OF THE GFS/NAM/GEM/ECMWF FOR HRLY TEMPS/DP...WND...POP... AND SKY. NAWAVE 4 FOR SEAS IN THE COASTAL WATERS. ADDED 15 PERCENT TO WINDS FOR GUSTS OVER LAND...25 PERCENT OVER COASTAL WATERS. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A HIGH PRESSURE RIDGE WILL BE IN PLACE OVER THE AREA AT THE START OF THE LONG TERM. A LOW PRESSURE SYSTEM MOVING UP THE EAST COAST AT THE START OF THE PERIOD THE GFS PLACES IT ALONG THE GULF STREAM EAST OF NJ...THE ECMWF ALONG THE COAST OF VA. AND THE GEM PLACES IT EAST OF CAPE COD...SOUTH OF SW NOVA SCOTIA. BY WED MRNG THE GFS MOVES THE LOW NORTH TO JUST SOUTH OF CAPE COD...WITH THE PRECIP SHIELD EXTENDING INTO DOWNEAST MAINE...THE ECMWF MOVES THE LOW TO DELMARVA...KEEPS THE PCPN SHIELD SOUTH OF CAPE COD. THE GEM MOVES THE LOW TO A POSITION SOUTH OF CENTRAL NOVA SCOTIA WELL EAST OF OUR AREA. A NEW LOW OVER THE CENTRAL MIDWEST WITH A COLD FRONT THAT EXTENDS FROM NORTHERN QUEBEC SW TO THE CENTRAL GREAT LAKES REGION. THE LOW WILL MOVE EAST AND BY THUR MRNG THE GFS MOVE IT TO THE ERN GREAT LAKES REGION...WITH ITS WARM FRONT EXTENDING INTO NRN MAINE. THE ECMWF IS A BIT SLOWER WITH THE FORWARD MVMNT OF THIS LOW...MOVING IT TO LAKE HURON. BY THURS EVNG...THE ECMWF CATCHES UP A BIT. THE GFS MOVES THE LOW TO SRN QUEBEC/WRN MAINE. THE ECMWF MOVES THE LOW TO SW QUEBEC. FROM THURS EVNG THROUGH THE END OF THE PERIOD. THE GFS AND ECMWF ARE ABOUT ONE PERIOD OUT OF FAZE WITH THE GFS BEING THE FASTER OF THE TWO MODELS. UNSETTLED WEATHER WILL PERSIST FROM THURS EVNG THROUGH THE END OF THE PERIOD AS AN UPPER LOW SLOWLY FILLS OVER WEST CENTRAL QUEBEC SE OF JAMES BAY. LOADED THE SUPERBLEND FOR THE EXTENDED PERIOD OF THE FORECAST. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... NEAR TERM: IFR SETTING UP ACROSS KBHB AND POSSIBLY KBGR THIS MORNING WHILE THE NORTHERN TERMINALS WILL SEE VFR THIS MORNING GOING TO MVFR. MVFR CONDITIONS FOR ALL TERMINALS INTO THE AFTERNOON. VFR EXPECTED ACROSS THE NORTHERN TERMINALS TONIGHT WHILE KBGR AND KBHB COULD SEE A BRIEF PERIOD OF IFR BEFORE CLEARING LATER TONIGHT AS THE FRONT CLEARS THE AREA. SHORT TERM: A FEW STRAY SHOWERS FOR BGR AND BHB EARLY IN THE PERIOD...OTHERWISE VFR CONDITIONS ALL SITES. && .MARINE... NEAR TERM: 1015 AM ...MAX WIND GUSTS WERE REDUCED TO 20 KT FOR THE REMAINDER OF THE DAY...DUE TO VERY STABLE SFC-500M LAPSE RATES. OTHERWISE...CURRENT SCA OVR THE OUTER MZS REMAIN IN PLACE. ORGNL DISC...CONDITIONS ATTM BELOW SCA LEVELS BOTH IN THE WINDS AND SEAS W/15 KTS AND 4 TO 5 FT. SEAS WILL CONT AT SCA LEVELS THRU THE AFTERNOON WINDS DROP OFF BEHIND THE FRONT TO LESS THAN 15 KTS AND SEAS WILL COME DOWN AS THE WIND GOES OFFSHORE. SHORT TERM: WINDS AND SEAS BELOW SCA CRITERIA THROUGH THE PERIOD. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR ANZ050- 051. && $$ NEAR TERM...VJN SHORT TERM...NORTON LONG TERM...NORTON AVIATION...VJN/NORTON MARINE...VJN/NORTON
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1242 PM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL BRING SHOWERS AND THUNDERSTORMS TODAY...WITH MUCH COOLER TEMPERATURES SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... QUICK EARLY AFTERNOON UPDATE TO SLIGHTLY PUSH BACK TIMING OF FRONT. STILL ANTICIPATE ONLY WIDELY SCATTER RED THUNDERSTORM COVERAGE TODAY SOUTH AND EAST OF PITTSBURGH AS CLOUD COVER WILL KEEP LOCATIONS NORTH AND WEST FROM REACHING TRIGGER TEMPERATURES AND LIFT ASSOCIATED WITH THE FRONT IS RELATIVELY WEAK. PREV DISCUSSION FOLLOWS.. LATEST RADAR/SAT/SFC OBS INDICATE THE ANAFRONT APPROACHING FROM THE WEST JUST NORTH AND EAST OF THE FORECAST AREA DRAPED ALONG THE SOUTHERN EDGE OF LAKE ERIE AND THEN DROPPING SOUTH JUST EAST OF CINCINNATI. ASSOCIATED PRECIPITATION ALONG AND JUST BEHIND THE FRONT HAS BEEN MAINLY LIGHT SHOWERS...BUT AS THE FRONT SLOWLY TRANSITIONS EAST ISOLATED THUNDERSTORMS SHOULD DEVELOP AS WELL OVER AREAS WHERE THERE HAS BEEN SUFFICIENT SFC HEATING TO CONTRIBUTE TO INSTABILITY. THE 12Z NAM APPEARS TO HAVE TRENDED SLOWER...WHICH IS GOOD AS ALL 00Z AND 06Z RUNS LOOKED TOO FAST WITH THE PROGRESSION OF THE FRONT. THE GFS AND LOCALLY RUN HIRES WRF MODELS WHICH USE GFS BOUNDARY CONDITIONS SEEMED TO HAVE THE BEST HANDLE ON THE SITUATION AND ADJUSTMENTS TO THE FORECAST FOR TODAY WERE LARGELY BASED ON THAT ALONG WITH 12Z SOUNDING DATA...WITH LAST MINUTE TWEAKS AS THE 12Z HRRR RUN FINALLY BEGAN TO SLOW THINGS DOWN AS WELL. WITH THAT...HAVE PARED BACK THE PRECIPITATION FORECAST BY CUTTING BACK ON PREFRONTAL AND POSTFRONTAL POPS AS THERE IS BETTER CONFIDENCE IN TIMING. BY THIS EVENING THE FRONT SHOULD BE LARGELY SOUTH OF THE FORECAST AREA WITH MUCH DRIER AIR AND COOLER TEMPERATURES IN ITS WAKE. TEMPERATURES TODAY WILL BE HIGHEST SOUTH AND EAST OF PITTSBURGH NEAR 80...WITH LOWER TO MID 70S FAR NORTH. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... DRY HIGH PRESSURE WILL DOMINATE THROUGH SUNDAY NIGHT. AS HIGH SHIFTS EAST MONDAY MODELS AGREE ON LOW PRESSURE DEVELOPING ALONG THE MID ATLANTIC COAST BUT DIFFER ON PLACEMENT OF DEEPER MOISTURE. WOULD EXPECT BULK OF ANY ACTIVITY TO REMAIN EAST OF THE RIDGES AND HAVE LOW CHC TO CHC POPS MONDAY IN THE SOUTHEAST RIDGES. BY TUESDAY A SHORTWAVE WILL WORK QUICKLY EAST IN ZONAL FLOW WITH INCREASING LOW AND MID LEVEL MOISTURE. WITH A RATHER WEAK SYSTEM HAVE GONE WITH SLIGHT CHANCE POPS. TEMPERATURES WILL REBOUND TO ABOVE SEASONAL AVERAGES BY TUESDAY. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... INCRG PCPN CHCS ARE EXPD WED INTO THU AS LOW PRES ADVNS ACRS THE GT LKS AND UPR OH VLY RGN. SFC HIGH PRES WL BLD IN BY LT WK INTO THE WKEND UNDER GENL COOL NERN CONUS UPR TROFG. THE COOL UPR TROFG WL ALLOW TEMPS TO FALL FM NR SEASONAL LVLS MID WK...TO SVRL DEG BLO AVG BY LT WK INTO THE WKEND. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... GENL VFR CONDS ARE EXPD UNTIL A CDFNT ADVNS ACRS THE RGN TDA WITH MVFR CONDS IN CU/SC AND OCNL SHWRS EXPD. BEST CHC FOR AFTN TSTMS EXPD TO BE S OF PIT WITH BETTER INSTBY SO INCLUDED A TEMPO TS MENTION IN THE MGW TAF. EXP A WSHFT FM SW TO NW WITH FROPA...AND AN EVENTUAL CLRG TREND BY THIS EVE AS THE FNT FURTHER EXITS. AREAS OF MVFR FOG IS EXPD TO DVLP LT TNGT ESP WHERE CLRG TAKES PLACE AFT SUNSET. OUTLOOK.../SUNDAY THROUGH WEDNESDAY/... RSTRNS ARE PSBL WITH A MD WK LOW PRES SYSTEM. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS LAS VEGAS NV
945 AM PDT SAT SEP 6 2014 .SYNOPSIS...A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS MAINLY THE HIGHER TERRAIN OF NORTHWEST ARIZONA...FAR SOUTHERN NEVADA AND EASTERN CALIFORNIA THIS AFTERNOON. THE REST OF THE AREA WILL SEE DRY CONDITIONS UNDER SOUTHWEST FLOW. MOISTURE IS FORECAST TO INCREASE SUNDAY INTO MONDAY RESULTING IN A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS ACROSS MUCH OF THE AREA. HEAVY RAIN AND FLASH FLOODING WILL BE A CONCERN FOR MUCH OF THE MOHAVE DESERT SUNDAY THROUGH MONDAY NIGHT. && .UPDATE...NORBERT STRENGTHENED TO A CATEGORY 3 HURRICANE OVERNIGHT BUT IS FORECAST TO WEAKEN THE REST OF TODAY AS IT DRIFTS NORTH INTO COOLER WATERS. 12Z HI RES AND HRRR MODELS STILL INDICATE THE POTENTIAL FOR ISOLATED CONVECTION OVER THE HIGHER TERRAIN OF MOHAVE, CLARK AND SAN BERNARDINO COUNTY THIS AFTERNOON/EARLY EVENING. THIS COVERED IN CURRENT FORECAST SO NOT UPDATE NECESSARY. TROPICAL MOISTURE STILL SLATED TO SURGE NORTH INTO THE AREA SUNDAY AND LINGER THROUGH TUESDAY. WILL ADDRESS ANY CHANGES FOR THOSE PERIODS THIS AFTERNOON. && .PREV DISCUSSION... 304 AM PDT SAT SEP 6 2014 .SHORT TERM...THROUGH SUNDAY NIGHT...THE MOISTURE SURGE THAT STARTED YESTERDAY HAS TAKEN A BIT OF A PAUSE. SURFACE DEWPOINTS EARLY THIS MORNING WERE IN THE 20S AND 30S IN THE NORTHWEST PART OF THE CWA WITH 40S AND 50S SOUTHEAST. NOT EXPECTING MUCH NORTHWARD PROGRESS OF THE MOISTURE TODAY WITH A SLIGHT CHANCE OF THUNDERSTORMS LIMITED TO GENERALLY AREAS SOUTHEAST OF LAS VEGAS. HURRICANE NORBERT IS FORECAST TO WEAKEN AND TRACK NORTHWEST THEN NORTH JUST WEST OF BAJA FOR THE NEXT FEW DAYS. AS A RESULT...MOISTURE WILL GRADUALLY INCREASE TONIGHT THROUGH SUNDAY NIGHT. PRECIPITABLE WATER VALUES BY SUNDAY NIGHT ARE FORECAST TO BE AROUND 2 INCHES AROUND LAKE HAVASU WITH ONE INCH VALUES APPROACHING THE NORTHERN EDGE OF OUR FORECAST AREA. PRECIPITATION CHANCES WILL STILL BE LIMITED TO AREAS SOUTHEAST OF LAS VEGAS TONIGHT BUT WILL SPREAD ACROSS THE REST OF THE FORECAST AREA SUNDAY AND SUNDAY NIGHT. WITH SUCH DEEP MOISTURE ACROSS THE MOHAVE DESERT...SHOWERS AND THUNDERSTORMS THAT DEVELOP WILL BE EFFICIENT RAINFALL PRODUCERS...LEADING TO A THREAT OF FLASH FLOODING AND THE FLASH FLOOD WATCH STILL LOOKS GOOD. .LONG TERM...MONDAY THROUGH FRIDAY. MONDAY...BY MONDAY MORNING WIDESPREAD DEEP MOISTURE [SOME OF WHICH WILL BE ASSOCIATED WITH THE REMNANTS OF WHAT IS CURRENTLY HURRICANE NORBERT] IS FORECAST TO BE IN PLACE ACROSS MOST IF NOT ALL OF THE FORECAST AREA. THE LATEST 00Z LAS VEGAS GFS BUFR SOUNDING FOR 15Z MONDAY INDICATES A PEAK PRECIPITABLE WATER VALUE OF 1.89 INCHES WHICH WOULD CHALLENGE THE SEPTEMBER RECORD OF 1.88 INCHES WHICH WAS SET ONLY LAST YEAR. IN FACT SO MUCH MOISTURE WILL BE IN PLAY THAT SIGNIFICANT CLOUD COVERAGE WILL LIKELY LIMIT SIGNIFICANT...WIDESPREAD DESTABILIZATION MONDAY. FORECAST SOUNDINGS ACROSS THE REGION SHOW SLIGHT WARMING ALOFT WHILE LOW LEVEL TEMPERATURES COOL. AS A RESULT I HAVE BOOSTED POPS AREA WIDE BUT AT THIS POINT IT APPEARS THAT PRECIPITATION MAY FALL MAINLY AS LIGHT TO MODERATE RAIN SHOWERS WITH ISOLATED TO SCATTERED EMBEDDED THUNDERSTORMS WITH HEAVY RAIN [HAVE ADJUSTED THE WEATHER GRIDS ACCORDINGLY]. MODELS ARE IN DECENT AGREEMENT THAT THE BEST CHANCES FOR RAIN WILL BE NORTHEAST OF A TONOPAH-PAHRUMP-PARKER LINE ASSOCIATED WITH UPPER LEVEL DIVERGENCE AHEAD OF AN UPPER LEVEL SHORTWAVE SWINGING THROUGH CALIFORNIA. THAT SAID...CHANCES OF RAIN AND THUNDERSTORMS EXIST ACROSS THE ENTIRE REGION. PRECIPITATION CHANCES WILL CONTINUE THROUGH MONDAY NIGHT. TUESDAY...ON TUESDAY THE AFOREMENTIONED SHORTWAVE WILL PUSH EAST ACROSS THE FORECAST AREA. THIS WILL PROVIDE ENOUGH DYNAMICS FOR ANOTHER DAY OF ISOLATED TO SCATTERED CONVECTION ACROSS MUCH OF THE AREA. THE BEST CHANCES WILL BE ACROSS LINCOLN...CLARK AND MOHAVE COUNTIES. HOW MUCH THUNDERSTORM ACTIVITY THAT DEVELOPS WILL AGAIN BE STRONGLY TIED TO THE AMOUNT OF CLOUD COVER THROUGH THE MORNING/EARLY AFTERNOON HOURS. AT THIS POINT IT APPEARS THAT IT MAY BE A GAME TIME DECISION AS TO WHETHER THE FLASH FLOOD WATCH WILL NEED TO BE EXTENDED THROUGH TUESDAY. DRIER AIR WILL BEGIN TO FILTER IN FROM THE WEST THROUGH THE DAY SHUTTING DOWN PRECIP CHANCES. WEDNESDAY THROUGH FRIDAY...LEFT IN JUST A SLIGHT CHANCE OF PRECIPITATION ACROSS EASTERN MOHAVE COUNTY WEDNESDAY TO ACCOUNT FOR ANY RESIDUAL MOISTURE IN PLACE. OTHERWISE DRIER CONDITIONS AND REBOUNDING TEMPERATURES ARE EXPECTED. && .AVIATION...FOR MCCARRAN...EASTERLY COMPONENT LATE THIS MORNING/AFTERNOON UP TO 10 KTS AT TIMES. WINDS WILL BECOME MORE SOUTHEASTERLY OR SOUTHERLY AGAIN THIS AFTERNOON OR EARLY THIS EVENING AROUND 10KTS...CONTINUING TONIGHT. CLEAR SKIES EARLY TODAY WITH FEW-SCT CUMULUS CLOUDS DEVELOPING LATE THIS MORNING AND THIS AFTERNOON. CLOUDS AND THUNDERSTORM CHANCES WILL BE INCREASING SUNDAY THROUGH MONDAY AS MOISTURE FROM HURRICANE NORBERT SPREADS NORTHWARD. FOR THE REST OF SOUTHERN NEVADA...NORTHWEST ARIZONA...AND SOUTHEAST CALIFORNIA...SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON OVER MAINLY NORTHWEST ARIZONA AND EASTERN SAN BERNARDINO COUNTY. CLOUDS AND THUNDERSTORM CHANCES WILL BE INCREASING SUNDAY THROUGH MONDAY AS MOISTURE FROM HURRICANE NORBERT SPREADS NORTHWARD. WINDS SHOULD FOLLOW TYPICAL DIURNAL TRENDS THROUGH THE TAF PERIOD. LIGHT DRAINAGE WINDS THROUGH EARLY THIS MORNING WILL BECOME MAINLY SOUTHERLY DURING THE DAY GENERALLY 10-15 KTS. .SPOTTER INFORMATION STATEMENT... SPOTTER ACTIVATION IS NOT EXPECTED THROUGH SATURDAY. SPOTTER ACTIVATION MAY BE NEEDED FOR CLARK, MOHAVE AND SAN BERNARDINO COUNTIES OF THE FORECAST AREA SUNDAY THROUGH TUESDAY. && $$ UPDATE...PIERCE SHORT TERM/AVIATION...HARRISON LONG TERM...WOLCOTT FOR MORE FORECAST INFORMATION...SEE US ON OUR WEBPAGE: HTTP://WEATHER.GOV/LASVEGAS OR FOLLOW US ON FACEBOOK AND TWITTER
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
313 PM EDT SAT SEP 6 2014 .SYNOPSIS... WAVES OF SHOWERS AND A FEW THUNDERSTORMS WITH HEAVY RAINFALL WILL CONTINUE THROUGH MONDAY AS LOW PRESSURE ALONG THE GEORGIA COAST LINKS UP WITH A COLD FRONT DIPPING IN FROM THE NORTH. AS THE LOW EXITS MONDAY NIGHT...A GRADUAL AND WARMING DRYING TREND SHOULD DEVELOP TUESDAY AND PERSIST INTO LATE NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 2 PM SATURDAY...ONGOING DIURNAL CONVECTION INLAND WILL LINGER INTO THE EVENING HOURS BEFORE THE LOSS OF HEATING BRINGS ABOUT ITS DEMISE. COVERAGE WILL VARY FROM LOW CHANCE TO LIKELY AT TIMES WITH STORMS HAVING THE ABILITY TO DROP SIGNIFICANT RAINFALL IN A SHORT PERIOD OF TIME. HOWEVER STORM MOVEMENT IS FAST ENOUGH TO LIMIT FLOODING POTENTIAL TO TRAINING STORMS. CLOSER TO THE COAST LINGERING DEBRIS CLOUD FROM THIS MORNINGS CONVECTION HAS SO FAR INHIBITED HEATING...THUS LIMITING INSTABILITY AND STORM DEVELOPMENT...ESPECIALLY ACROSS COASTAL NC. ALTHOUGH CLOUD COVER WILL CONTINUE TO DIMINISH ALONG THE COAST THIS AFTERNOON IT LOOKS LIKE THERE MAY NOT BE ENOUGH TIME TO GENERATE ENOUGH INSTABILITY FOR ANYTHING MORE THAN ISOLATED SHOWERS. HAVE BACKED OFF ON POP FOR THE AFTERNOON HOURS ALONG THE COAST...THOUGH AN ISOLATED SHOWER OR THUNDERSTORM WILL STILL BE POSSIBLE. DEEP MOISTURE PLUME WILL SPREAD NORTH INTO THE REGION TONIGHT PUSHING PRECIPITABLE WATER VALUES OVER 2 INCHES. AT THE SAME TIME LOW LEVEL JETTING AHEAD OF THE SLOWLY ADVANCING COLD FRONT INCREASES TO 20 TO 25 KT. LOW LEVEL CONVERGENCE ALONG THE COASTAL TROUGH COMBINED WITH THE NOCTURNAL JETTING AND THE DEEP MOISTURE SHOULD PRODUCE OFFSHORE CONVECTION...SOME OF WHICH WILL LIKELY MOVE ONSHORE OVERNIGHT. NOT CONFIDENT SHOWERS AND THUNDERSTORMS WILL MOVE FAR INLAND...GIVEN THE LOCATION OF THE TROUGH NEAR THE COAST AND LIMITED INSTABILITY IN THESE AREAS. WHILE IT IS WEAK FOR THE FIRST TIME IN SEVERAL DAYS THERE WILL BE SOME UPPER LEVEL SUPPORT AS FLOW ALOFT BECOMES WEAKLY DIVERGENT. THIS COULD AID ONGOING STORMS BUT BY ITSELF WOULD PROBABLY NOT BE STRONG ENOUGH TO GENERATE CONVECTION. HEAVY RAIN WILL BE POSSIBLE WITH ANY STORMS THAT DO DEVELOP GIVEN THE DEEP MOISTURE AND FREEZING LEVEL OF 15.6K FT OVERNIGHT. STORM MOTIONS WILL REMAIN ABOVE 10 KT SO STORM MOTION SHOULD NOT CONTRIBUTE TO FLOODING BUT TRAINING OR BACK BUILDING STORMS WOULD HAVE POTENTIAL TO CAUSE LOCALIZED FLOODING GIVEN THE EXPECTED HIGH PRECIPITATION RATES. CLOUD COVER AND MOISTURE WILL HELP KEEP LOWS IN THE 70S...BUT ALONG THE COAST RAINFALL WILL KEEP TEMPS COOLER. COAST SHOULD STILL END UP WARMEST BUT BY A COUPLE DEGREES AT MOST. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 PM SATURDAY...A NON-FRONTAL LOW OVER EASTERN GEORGIA AND SOUTHERNMOST SOUTH CAROLINA WILL HELP ADVECT IN A RICH TROPICAL AIRMASS INLAND WITH PRECIPITABLE WATER VALUES 2.0 TO 2.3 INCHES. OFFSHORE SHOWERS AND T-STORMS SHOULD SWEEP ONSHORE SUNDAY MORNING ACROSS THE GRAND STRAND AND CAPE FEAR REGION...WITH DAYTIME HEATING NUDGING THE BEST COVERAGE OF SHOWERS & STORMS INLAND DURING THE AFTERNOON HOURS. A SYNOPTIC COLD FRONT OVER THE CENTRAL CAROLINAS WILL SLIP SOUTHEASTWARD INTO THE COASTAL PLAIN SUNDAY AFTERNOON...INTERCEPTING THE FEED OF TROPICAL MOISTURE AND STALLING ABOUT HALFWAY BETWEEN I-95 AND THE COAST. THIS IS A GOOD SETUP FOR SHOWERY WEATHER WITH LOCALIZED HEAVY RAIN...AND FORECAST POPS SUNDAY RANGE FROM 60-80 PERCENT. THE SOUTH CAROLINA LOW IS BEING SUSTAINED AT LEAST IN PART BY CONVECTIVE PROCESSES. THE CYCLONIC SWIRL EXTENDS UP THROUGH 500 MB WITH A RIDGE PRESENT UP AT 200/300 MB. WHILE THE ODDS FAVOR THIS SYSTEM NOT INTENSIFYING INTO A NAMED TROPICAL CYCLONE (THE CENTER IS EXPECTED TO REMAIN INLAND) IT MAY BRING WEATHER REMINISCENT TO THAT OF A WEAK TROPICAL DEPRESSION. WAVES OF SHOWERS...SOME HEAVY...WILL CONTINUE TO SWEEP ONSHORE SUNDAY NIGHT INTO MONDAY. AS THE COLD FRONT REMAINS STALLED ACROSS THE COASTAL PLAIN MONDAY...THE LOW SHOULD LINK UP WITH THIS BOUNDARY AND BEGIN TO MOVE NORTHEASTWARD...FINALLY REACHING SOUTHEASTERN NORTH CAROLINA MONDAY NIGHT AND ACCELERATING OUT TO THE NORTHEAST AFTER MIDNIGHT. THIS SHOULD SPELL AN END TO THE SHOWERY WEATHER AND SHOULD PUSH THE FRONT OFF THE COAST. FROM AN AREAL STANDPOINT WE ARE EXPECTING AS MUCH AS 2.5 INCHES OF RAIN ALONG THE COAST TONIGHT THROUGH MONDAY NIGHT WITH 1.0 TO 1.7 INCHES NEAR/WEST OF I-95. ISOLATED AREAS COULD REALISTICALLY PICK UP 5 TO 7 INCHES. THE 12Z NAM WAS AN OUTLIER VERSUS THE GFS/ECMWF WITH REGARDS TO HOW MUCH THE SURFACE LOW AND ASSOCIATED WIND/ADVECTION FIELDS INTENSIFY...BUT CANNOT BE RULED OUT. SHOULD CONFIDENCE GROW THAT EXCESSIVE RAINFALL WILL OCCUR A FLOOD WATCH MAY BE NEEDED FOR PORTIONS OF COASTAL SOUTH AND NORTH CAROLINA. DIURNAL TEMPERATURE RANGES WILL BE CONSTRICTED BY ALL THE CLOUDS AND PRECIPITATION...PARTICULARLY ON MONDAY WHEN A SOLID OVERCAST MAY PERSIST FOR A GOOD PORTION OF THE DAY WEST OF THE STALLED FRONT. MOS CONSENSUS TEMPERATURES LOOK REASONABLE -- EXCEPT FOR HIGHS MONDAY WHERE I HAVE TRIMMED UP TO FIVE DEGREES OFF WEST OF THE FRONT. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 300 PM SATURDAY...LOW PRESSURE WILL MOVE UP THE CAROLINA COAST ALONG A LINGERING COLD FRONT AS WEAK HIGH PRESSURE BUILDS IN BEHIND IT THROUGH TUESDAY. ANY LINGERING CLOUDS OR SHOWERS TUES WILL DIMINISH THROUGH LATE TUES INTO WED AS DRY AIR MOVES IN ABOVE H85. PCP WATER VALUES UP CLOSE TO 2 INCHES EARLY TUES WILL DROP DOWN TO 1.5 INCHES BY TUES EVE AND EVEN FURTHER BY WED MORNING. WEAK HIGH PRESSURE WILL REMAIN AT THE SURFACE WHILE RIDGE IN THE MID TO UPPER LEVELS BUILDS BACK UP THROUGH THE CAROLINAS THROUGH MID WEEK WITH PLENTY OF DRY AIR AND SUBSIDENCE ALOFT. MAY INCLUDE A VERY LOW END CHC OF SHWRS ON WED AND THURS BUT OVERALL EXPECT PLENTY OF SUNSHINE WITH SOME LOCALIZED CU DEVELOPMENT AND POSSIBLY A STRAY SHWR. BY LATE THURS INTO FRI CHC OF PCP WILL INCREASE AS RIDGE ALOFT GETS SUPPRESSED FARTHER SOUTH AS A SHORTWAVE BEGINS TO DIG DOWN AS IT RIDES ACROSS THE GREAT LAKES. THIS SHORTWAVE WILL PUSH A COLD FRONT INTO THE CAROLINAS BY FRI INTO SATURDAY WITH MORE WIDESPREAD SHWR AND TSTMS EXPECTED HEADING INTO THE WEEKEND. TEMPS NEAR NORMAL ON TUES IN LINGERING CLOUDS AND SHWRS WILL WARM UP AGAIN THROUGH MID WEEK AS H5 HEIGHTS RISE WITH BUILDING RIDGE. EXPECT TEMPS IN THE MID 80S ON TUES WILL BE BACK UP AROUND 90 OR SO BY THURS AND FRI. BY SATURDAY CLOUDS AND SHWRS ASSOCIATED WITH COLD FRONT WILL KEEP TEMPS IN THE 80S. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 18Z...THE HEAVIEST ACTIVITY SEEMS TO BE OVER...FOR NOW. LOOK FOR CONVECTION DEVELOPING MAINLY INLAND THIS AFTERNOON. THE HRRR IS NOT TOO IMPRESSED...WITH ONLY LIGHT SCATTERED ACTIVITY THIS AFTERNOON. WILL STAY WITH MAINLY VCSH INLAND WITH A TEMPO GROUP ALONG THE COAST. TONIGHT...DEEP MOISTURE WILL BE ON THE INCREASE WITH ONSHORE FLOW AND AN INVERTED TROUGH DEVELOPING. LOOK FOR SOME GOOD HEAVY NOCTURNAL SHOWERS MAINLY AFTER 06Z WITH SOME MVFR/IFR CONDITIONS. THE WORST CASE CEILINGS WILL PROBABLY BE INLAND...WITH IFR EXPECT OVERNIGHT THROUGH MID MORNING. MAINLY LIGHT SOUTHERLY FLOW THROUGH THE PERIOD. EXTENDED OUTLOOK...INCLEMENT WEATHER WILL CONTINUE SUNDAY NIGHT AND MONDAY WITH INTERMITTENT IFR CONDITIONS EXPECTED. IMPROVING CONDITIONS TUESDAY AND WEDNESDAY. SLIGHT CHANCE FOR SHOWERS THURSDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 2 PM SATURDAY...ALTHOUGH GRADIENT WILL CHANGE LITTLE OVERNIGHT THE STRENGTHENING LOW LEVEL JET WILL RESULT IN SLIGHTLY HIGHER WIND SPEEDS THAN PREVIOUS NIGHTS. SOUTH TO SOUTHWEST FLOW WILL HANG IN THE 10 TO 15 KT RANGE WITH POTENTIAL FOR THE OCCASIONAL GUST EXCEEDING 15 KT. SEAS WILL CONTINUE 2 TO 3 FT OVERNIGHT BUT WITH SOME ISOLATED 4 FT THROWN IN DUE TO PROLONGED SOUTHERLY FETCH AND THE SLIGHT INCREASE IN SPEEDS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 PM SATURDAY...A COLD FRONT OVER THE CENTRAL CAROLINAS SUNDAY MORNING WILL SAG INTO THE COASTAL PLAIN BY AFTERNOON... STALLING AS IT ENCOUNTERS AN AREA OF LOW PRESSURE OVER SOUTHERNMOST SOUTH CAROLINA. THIS LOW IS BEING MAINTAINED (AT LEAST IN PART) BY SHOWER AND THUNDERSTORM ACTIVITY ONGOING AROUND IT. WHILE THE ODDS DO NOT FAVOR THE DEVELOPMENT OF A NAMED TROPICAL SYSTEM...THIS SITUATION WILL HAVE SOME PARALLELS TO WHAT WE MIGHT EXPERIENCE DURING A WEAK TROPICAL DEPRESSION. THE LOW OVER SOUTH CAROLINA WILL LIFT SLOWLY NORTHEASTWARD ALONG THE FRONT SUNDAY NIGHT AND MONDAY...REACHING SOUTHEASTERN NORTH CAROLINA MONDAY NIGHT. THIS MEANS WE`LL HAVE AN EXTENDED PERIOD OF HEAVY SHOWERS AND MODERATE SOUTH WINDS SUNDAY THROUGH MONDAY EVENING... WITH WINDS VEERING MORE WESTERLY LATE MONDAY NIGHT AS THE LOW ACCELERATES NORTHEASTWARD THROUGH EASTERN NORTH CAROLINA. AT THIS TIME THE HIGHEST WINDS WE ARE EXPECTING ARE 15-20 KNOTS WITH GUSTS IN THE LOWER 20S. THIS IS OF COURSE VERY DEPENDENT ON HOW MUCH (IF ANY) STRENGTHENING OCCURS OF THE SYSTEM BEYOND THE WEAK FRONTAL LOW NOW EXPECTED. ASSUMING THESE WINDS PAN OUT SEAS SHOULD BUILD TO 4-5 FEET AWAY FROM SHORE...HIGHEST SUNDAY NIGHT INTO MONDAY MORNING ACROSS THE WATERS SOUTH OF CAPE FEAR. LONG TERM /TUESDAY THROUGH THURSDAY/... AS OF 300 PM SATURDAY...LOW PRESSURE ALONG LINGERING FRONT ALONG THE CAROLINA COAST EARLY TUES WILL LIFT OFF TO THE NORTHEAST THROUGH THE DAY. THIS MAY CAUSE VARIABLE WINDS OVER THE COASTAL WATERS ON TUES BUT OVERALL SHOULD SEE SW-W WINDS BECOMING NORTHERLY AND LIGHTEN THROUGH EARLY WED. WEAK HIGH PRESSURE OVER THE WATERS WILL MAINTAIN LIGHT AND VARIABLE WINDS COMING AROUND TO THE SOUTH BY THURS BUT REMAINING 10 KTS OR LESS. THE OFF SHORE WINDS WILL KNOCK SEAS DOWN THROUGH TUES FROM 2 TO 4 FT EARLY DOWN TO 3 FT OR LESS TUES NIGHT THROUGH THURS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...TRA NEAR TERM...III SHORT TERM...TRA LONG TERM...RGZ AVIATION...HDL/III
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
215 PM EDT SAT SEP 6 2014 .SYNOPSIS... SHOWERS AND THUNDERSTORMS WILL CONTINUE TO INCREASE IN COVERAGE TODAY AS A COLD FRONT APPROACHES. LOW PRESSURE MAY ENHANCE THE RAINFALL SUNDAY AND MONDAY. A GRADUAL DRYING TREND WILL GET UNDERWAY ON TUESDAY AND PERSIST INTO LATE NEXT WEEK WHILE AFTERNOON HIGHS CLIMB. && .NEAR TERM /THROUGH TONIGHT/... AS OF 2 PM SATURDAY...ONGOING DIURNAL CONVECTION INLAND WILL LINGER INTO THE EVENING HOURS BEFORE THE LOSS OF HEATING BRINGS ABOUT ITS DEMISE. COVERAGE WILL VARY FROM LOW CHANCE TO LIKELY AT TIMES WITH STORMS HAVING THE ABILITY TO DROP SIGNIFICANT RAINFALL IN A SHORT PERIOD OF TIME. HOWEVER STORM MOVEMENT IS FAST ENOUGH TO LIMIT FLOODING POTENTIAL TO TRAINING STORMS. CLOSER TO THE COAST LINGERING DEBRIS CLOUD FROM THIS MORNINGS CONVECTION HAS SO FAR INHIBITED HEATING...THUS LIMITING INSTABILITY AND STORM DEVELOPMENT...ESPECIALLY ACROSS COASTAL NC. ALTHOUGH CLOUD COVER WILL CONTINUE TO DIMINISH ALONG THE COAST THIS AFTERNOON IT LOOKS LIKE THERE MAY NOT BE ENOUGH TIME TO GENERATE ENOUGH INSTABILITY FOR ANYTHING MORE THAN ISOLATED SHOWERS. HAVE BACKED OFF ON POP FOR THE AFTERNOON HOURS ALONG THE COAST...THOUGH AN ISOLATED SHOWER OR THUNDERSTORM WILL STILL BE POSSIBLE. DEEP MOISTURE PLUME WILL SPREAD NORTH INTO THE REGION TONIGHT PUSHING PRECIPITABLE WATER VALUES OVER 2 INCHES. AT THE SAME TIME LOW LEVEL JETTING AHEAD OF THE SLOWLY ADVANCING COLD FRONT INCREASES TO 20 TO 25 KT. LOW LEVEL CONVERGENCE ALONG THE COASTAL TROUGH COMBINED WITH THE NOCTURNAL JETTING AND THE DEEP MOISTURE SHOULD PRODUCE OFFSHORE CONVECTION...SOME OF WHICH WILL LIKELY MOVE ONSHORE OVERNIGHT. NOT CONFIDENT SHOWERS AND THUNDERSTORMS WILL MOVE FAR INLAND...GIVEN THE LOCATION OF THE TROUGH NEAR THE COAST AND LIMITED INSTABILITY IN THESE AREAS. WHILE IT IS WEAK FOR THE FIRST TIME IN SEVERAL DAYS THERE WILL BE SOME UPPER LEVEL SUPPORT AS FLOW ALOFT BECOMES WEAKLY DIVERGENT. THIS COULD AID ONGOING STORMS BUT BY ITSELF WOULD PROBABLY NOT BE STRONG ENOUGH TO GENERATE CONVECTION. HEAVY RAIN WILL BE POSSIBLE WITH ANY STORMS THAT DO DEVELOP GIVEN THE DEEP MOISTURE AND FREEZING LEVEL OF 15.6K FT OVERNIGHT. STORM MOTIONS WILL REMAIN ABOVE 10 KT SO STORM MOTION SHOULD NOT CONTRIBUTE TO FLOODING BUT TRAINING OR BACK BUILDING STORMS WOULD HAVE POTENTIAL TO CAUSE LOCALIZED FLOODING GIVEN THE EXPECTED HIGH PRECIPITATION RATES. CLOUD COVER AND MOISTURE WILL HELP KEEP LOWS IN THE 70S...BUT ALONG THE COAST RAINFALL WILL KEEP TEMPS COOLER. COAST SHOULD STILL END UP WARMEST BUT BY A COUPLE DEGREES AT MOST. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 AM SATURDAY...VERY ACTIVE WEATHER IS EXPECTED THROUGH THE SHORT TERM PERIOD WITH POTENTIAL FOR SOME HEAVY RAINFALL. THERE IS JUST ENOUGH VARIATION IN MODEL SOLUTIONS TO SAY FOR SURE WHEN THE BEST WINDOW OF OPPORTUNITY FOR THAT WILL BE. PIEDMONT TROUGH NEARLY LINKED WITH NORTHWARD EXTENSION OF CARIBBEAN TROPICAL WAVE EXTENDED JUST WEST OF FL RIGHT NOW. THROUGH SUNDAY THIS MOISTURE IS PROGGED TO ADVECT NORTH AND EASTWARD...SURGING INTO THE COASTAL CAROLINAS. MULTIPLE SOURCES OF LIFT INCLUDE BUT ARE NOT LIMITED TO THE SEA BREEZE, THE PIEDMONT TROUGH, AND PVA ASSOC WITH THE MID LEVEL SYSTEM MOVING NE UP THE COAST. A COLD FRONT WILL ALSO BE APPROACHING FROM THE NORTH TO PROVIDE A SQUEEZE PLAY FOR THIS MOISTURE TRYING TO MOVE NORTHWARD. WHERE THIS ZONE OF SURFACE-BASED OVERRUNNING SETS UP LIKELY STANDS TO SEE THE HEAVIEST RAINFALL ON SUNDAY. WRF IS A BIT NORTH OF THE REGION WHEREAS THE GFS TAKES AIM AT MOST OF THE COASTAL CAROLINAS. THE LATTER HALF OF THE PERIOD GETS TRICKY. THE GFS WOULD IMPLY THAT COPIOUS RAINS CONTINUE THROUGH ABOUT MONDAY MORNING. THEREAFTER THE SURFACE REFLECTION OF THE FL UPPER LOW MOVES NE ALONG THE FRONT AS A FAIRLY FLAT WAVE. THE WRF WHICH WAS INITIALLY A STRONG OUTLIER CONTINUES TO SHOW A SIMILAR SCENARIO. ITS MORE CLOSED OFF LOW IS SLOWER TO ZIPPER ITS WAY UP THE FRONT...BUT IT JUST SEEMS TO BE IMPLYING TOO MUCH BAROTROPIC/LATENT HEATING DRIVEN STRENGTHENING PROCESSES TAKING PLACE...ALL WHILE THE LOW REMAINS OVER LAND. ANY OF THOSE PROCESSES MAY VERY WELL TAKE PLACE BUT PROBABLY WELL AFTER IT HAS PASSED NORTH OF HATTERAS A LA THE CANADIAN GEM MODEL. THE ECMWF IS A RATHER NICE COMPROMISE SHOWING THAT MUCH OF MONDAY IS JUST AS WET FOR MOST AREAS AS SUNDAY...WHICH PERHAPS A MORE DEFINED COASTAL VS INLAND GRADIENT IN QPF...BOTH DAYS WETTEST ALONG THE COAST. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 300 AM SATURDAY...LOW LEVEL MOISTURE ASSOCIATED WITH DISSIPATING FRONT SHOULD LINGER FOR LOW END CHANCE POPS ESPECIALLY ALONG THE COAST. MID LEVEL ZONAL FLOW WILL BE DRYING OUT MUCH OF THE COLUMN ABOVE THE BOUNDARY LAYER THOUGH. WEDNESDAY LOOKS LIKE A TRANSITION BACK TO A WARM SEASON PATTERN WITH FLAT WEAK RIDGING ACROSS NRN GOMEX AND SRN U.S. WHILE BERMUDA HIGH STRUGGLES TO REASSERT ITSELF. THE LATTER FACT NOT THAT GREAT FOR DIURNAL CONVECTION-INDUCING LOW LEVEL MOISTURE ADVECTION BUT SOME FRONTAL MOISTURE MAY STILL LINGER. ISO POPS AND CLIMO TEMPS APPEAR A GOOD BET. THE MID LEVEL RIDGE INCREASES IN AMPLITUDE ON THURSDAY BRINGING A WARMER AFTERNOON WHILE INCREASING TROUGINESS OVER THE NRN PLAINS DRIVES A STRONG FRONT INTO THE GREAT LAKES. PREFRONTAL TROUGH DEVELOPS ACRS THE PIEDMONT ON FRIDAY WITH A LITTLE EXTRA MOISTURE FLUX INTO THE COASTAL PLAIN AS A RESULT. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 18Z...THE HEAVIEST ACTIVITY SEEMS TO BE OVER...FOR NOW. LOOK FOR CONVECTION DEVELOPING MAINLY INLAND THIS AFTERNOON. THE HRRR IS NOT TOO IMPRESSED...WITH ONLY LIGHT SCATTERED ACTIVITY THIS AFTERNOON. WILL STAY WITH MAINLY VCSH INLAND WITH A TEMPO GROUP ALONG THE COAST. TONIGHT...DEEP MOISTURE WILL BE ON THE INCREASE WITH ONSHORE FLOW AND AN INVERTED TROUGH DEVELOPING. LOOK FOR SOME GOOD HEAVY NOCTURNAL SHOWERS MAINLY AFTER 06Z WITH SOME MVFR/IFR CONDITIONS. THE WORST CASE CEILINGS WILL PROBABLY BE INLAND...WITH IFR EXPECT OVERNIGHT THROUGH MID MORNING. MAINLY LIGHT SOUTHERLY FLOW THROUGH THE PERIOD. EXTENDED OUTLOOK...INCLEMENT WEATHER WILL CONTINUE SUNDAY NIGHT AND MONDAY WITH INTERMITTENT IFR CONDITIONS EXPECTED. IMPROVING CONDITIONS TUESDAY AND WEDNESDAY. SLIGHT CHANCE FOR SHOWERS THURSDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 2 PM SATURDAY...ALTHOUGH GRADIENT WILL CHANGE LITTLE OVERNIGHT THE STRENGTHENING LOW LEVEL JET WILL RESULT IN SLIGHTLY HIGHER WIND SPEEDS THAN PREVIOUS NIGHTS. SOUTH TO SOUTHWEST FLOW WILL HANG IN THE 10 TO 15 KT RANGE WITH POTENTIAL FOR THE OCCASIONAL GUST EXCEEDING 15 KT. SEAS WILL CONTINUE 2 TO 3 FT OVERNIGHT BUT WITH SOME ISOLATED 4 FT THROWN IN DUE TO PROLONGED SOUTHERLY FETCH AND THE SLIGHT INCREASE IN SPEEDS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 AM SATURDAY...SWRLY GRADIENT WINDS WILL STILL BE QUITE `SEASONABLE` DESPITE COLD FRONT PUSHING INTO THE CAROLINAS. THE TEMPORAL PERSISTENCE OF THE FETCH HOWEVER MAY CAUSE THE OCCASIONAL 5 FT WAVE TO APPEAR ALONG OUTER EDGES OF NRN LEGS. HOW THE REMAINDER OF THE PERIOD UNFOLDS IS RATHER UNCERTAIN AS IT WILL INVOLVE LOW PRESSURE TRAVELING NORTH AND EAST ALONG THE STALLED FRONTAL BOUNDARY. SOME GUIDANCE IS PROBLEMATICALLY DEVELOPING A STRONG LOW THAT LOOKS LIKE IT IS BORNE OF TROPICAL STRENGTHENING DESPITE THE LOW REMAINING OVER LAND. THE SLOWER AND WEAKER MODELS ARE THUS PREFERRED AND EVEN THIS MAY PUSH WIND OR SEAS CLOSE TO BUT GENERALLY SHY OF SCEC CRITERIA. FUTURE MODEL RUNS SHOULD CLARIFY THESE UNCERTAINTIES. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 300 AM SATURDAY...THE DEPARTURE OF THE SURFACE LOW OF THE SHORT TERM AND THE APPARENT RAPID WEAKENING OF ITS ASSOCIATED FRONTAL BOUNDARY AND TUESDAY WINDS AND SEAS MAY FALL TO QUITE MINIMAL LEVELS WITH A GENERALLY OFFSHORE FLOW DIRECTION. A CONTINUED WEAKENING OF THE BOUNDARY ON WEDNESDAY SHOULD ALLOW FOR A GRADUAL TURN TO THE SOUTH WHILE WIND AND SEAS REMAIN MINIMAL. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...III SHORT TERM...MBB LONG TERM...MBB AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
425 PM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL CONTINUE MOVING THROUGH THE AREA TODAY. DRIER HIGH PRESSURE WILL BUILD IN FOR SUNDAY AND MONDAY...BEFORE WARMER AND MORE HUMID CONDITIONS RETURN ON TUESDAY AND WEDNESDAY. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL INCREASE BY THE MIDDLE OF THE WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... A CURRENT WIND ANALYSIS AT THE SURFACE SHOWS THAT THE COLD FRONT HAS CROSSED THROUGH THE VAST MAJORITY OF THE CWA...WITH NORTHWEST WINDS NOW REPORTED AT PORTSMOUTH AND FLEMING-MASON AIRPORTS. THE AIR MASS CHANGE WILL CONTINUE FOR THE NEXT SEVERAL HOURS...AS TEMPERATURES AND DEWPOINTS ARE STILL MUCH HIGHER IN THE SOUTHEASTERN CWA. NORTH OF THE BROKEN BAND OF LIGHT SHOWERS ACROSS THE HEART OF THE CWA...TEMPERATURES ARE ALREADY FALLING INTO THE UPPER 60S...WITH DEWPOINTS IN THE LOWER TO MID 60S. WITH LAPS ANALYSIS INDICATING SURFACE-BASED INSTABILITY OF AROUND 1000-1500 J/KG IN THE FAR SOUTHERN CWA...THERE STILL REMAINS A BRIEF CHANCE FOR THUNDER. HOWEVER...THE COLD ADVECTION WILL BRING THIS INSTABILITY TO AN END BY AROUND 21Z...WITH ONLY SHOWERS EXPECTED AFTER THAT. HRRR TRENDS INDICATE THAT THE SHOWERS OVER THE REST OF THE CWA WILL CONTINUE A DIMINISHING TREND THIS AFTERNOON AND EVENING...AND THE ENTIRE CWA WILL LIKELY BE DRY BY MIDNIGHT. SKIES ARE ALSO EXPECTED TO CLEAR...BUT THE FALLING DEWPOINTS WILL MAKE FOG UNLIKELY. THESE DRIER CONDITIONS MAY LEAD TO A BIG CHANGE IN MIN TEMPS FROM LAST NIGHT...WITH OUTLYING AREAS IN THE NORTHERN HALF OF THE CWA GETTING AS LOW AS 50 DEGREES TONIGHT. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... SPRAWLING HIGH PRESSURE WILL BE CENTERED OVER THE NORTHERN OHIO VALLEY ON SUNDAY MORNING...WITH A TREND TOWARD GRADUALLY DRIFTING EASTWARD THROUGH MONDAY MORNING. THE DRY AIR MASS WILL KEEP SIGNIFICANT MOISTURE SOUTH OF THE ILN CWA...LIMITING CLOUDS TO JUST A FEW CUMULUS. TEMPERATURES WILL STRUGGLE TO REACH NORMAL VALUES...AND THE GOING FORECAST FOR MAX TEMPS ON SUNDAY IS A FEW DEGREES BELOW CLIMATOLOGY. BY MONDAY MORNING...THE MAIN AXIS OF THE SURFACE HIGH WILL EXTEND FROM UPSTATE NEW YORK THROUGH MISSOURI. AN AREA OF SURFACE TROUGHING IS FORECAST TO DEVELOP ON THE WEST SIDE OF THE APPALACHIANS...AS A WEAK SHORTWAVE ALSO PASSES EASTWARD INTO THE OHIO VALLEY. THOUGH SIGNIFICANT MOISTURE ASSOCIATED WITH A SURFACE LOW WILL AFFECT THE ATLANTIC COAST FROM FLORIDA THROUGH DELAWARE...VERY LITTLE OF THE MOISTURE WILL BE DRAWN AS FAR WEST AS THE ILN CWA. THIS FEATURE WARRANTS ONLY A 20-POP GIVEN CURRENT MODEL PROJECTIONS. FORECAST MAX TEMPERATURES FOR MONDAY ARE VERY CLOSE TO CLIMATOLOGY. WITH A SLIGHT INCREASE IN WARM ADVECTION BEGINNING ON MONDAY NIGHT...MIN TEMPS GOING INTO TUESDAY MORNING REPRESENT AN INCREASE FROM BOTH SATURDAY AND SUNDAY NIGHTS. && .LONG TERM /TUESDAY THROUGH SATURDAY/... THE OPERATIONAL MODELS ARE IN FAIRLY GOOD AGREEMENT FOR THE LONG TERM PERIOD IN TERMS OF LARGE SCALE SYNOPTIC SYSTEMS. THERE ARE THE USUAL STRENGTH AND TIMING ISSUES. AS SUCH...HAVE LEANED ON A BLEND OF THE 12Z ECMWF...12Z GFS AND WPC GUIDANCE. ON TUESDAY...REGION WILL BE UNDER A ZONAL FLOW ALOFT. MODELS INDICATE THAT THERE SHOULD BE A DRY WEDGE IN TERMS OF DEEP MOISTURE AND A LACK OF INSTABILITY...SO HAVE KEPT THE FORECAST DRY DESPITE WEAK EMBEDDED DISTURBANCES WITHIN THE FLOW. SKIES WILL RANGE FROM MOSTLY SUNNY TO PARTLY CLOUDY. HIGHS WILL RANGE FROM THE THE LOWER TO MID 80S. THE UPR LVL FLOW PATTERN WILL UNDERGO AMPLIFICATION THROUGH THE REMAINDER OF THE LONG TERM PERIOD. ENERGY FROM OFF THE CA COAST WILL EJECT QUICKLY NE INTO THE PLAINS AND THEN TO THE WESTERN GREAT LAKES LATE TUESDAY NIGHT INTO WEDNESDAY. THIS ENERGY WILL TRY TO PHASE WITH ENERGY DIGGING FROM WESTERN CANADA INTO THE NORTHERN PLAINS WEDNESDAY INTO THURSDAY. THIS SCENARIO WILL ALLOW A LOW PRESSURE SYSTEM TO DEEPEN AS IT MOVES NORTHEAST THROUGH THE WESTERN GREAT LAKES INTO SE CANADA DURING THIS PERIOD...SENDING AN ATTENDANT COLD FRONT SOUTHEAST THROUGH OUR REGION. CURRENT FORECASTS SUGGEST THAT A STRONG LOW LEVEL JET AND WAA PCPN WILL BREAK OUT TO OUR WEST AND LIKELY SKIM OUR NW CWFA ON WEDNESDAY WITH THE REMAINDER OF THE REGION SEEING A CHANCE OF PCPN WITH AN ADVANCING WARM FRONT. THE BEST THREAT FOR THE ENTIRE REGION TO SEE PCPN WILL COME WEDNESDAY NIGHT INTO THURSDAY MORNING AS THE COLD FRONT SWINGS SOUTHEAST. THIS WILL BE A DYNAMIC SYSTEM WITH DECENT WIND ENERGY AND LOW LEVEL FRONTAL CONVERGENCE. AS SUCH...THE POTENTIAL FOR THUNDERSTORMS TO BE SEVERE WEDNESDAY NIGHT INTO THURSDAY MORNING WILL DEPEND ON THE DEGREE OF INSTABILITY...ALTHOUGH WITH WINDS OF LOWER 40 KNOTS AT 925 MB AND LOWER TO MID 50 KNOTS AT 850 MB...IT MAY NOT TAKE A WHOLE LOT. SPC HAS HIGHLIGHTED THE GREAT LAKES REGION/PARTS OF THE OHIO VALLEY IN A DAY 5 30 PERCENT RISK FOR SEVERE STORMS. WILL HIGHLIGHT THIS THREAT IN THE HWO...BUT WILL BROAD BRUSH IT AT THIS POINT IN TIME. COLD FRONT SHOULD PUSH SOUTHEAST AWAY FROM THE AREA ON THURSDAY WITH PCPN PUSHING OUT AS WELL. FOR THE PERIOD THURSDAY NIGHT INTO SATURDAY...A PRETTY DECENT MID LEVEL CLOSED LOW WILL TRAVERSE EAST/NORTHEAST THROUGH THE GREAT LAKES AND SOUTHEAST CANADA THROUGH THE PERIOD. THIS WILL EVENTUALLY ALLOW AN EXPANSIVE AREA OF SURFACE HIGH PRESSURE TO BUILD INTO THE REGION BY SATURDAY. ANY SPOTTY SHOWER ACTIVITY APPEARS TO BE RELEGATED CLOSER TO THE GREAT LAKES ON FRIDAY SO HAVE LEFT THE FORECAST DRY. TEMPERATURES WILL SHOW A SUBSTANTIAL COOL DOWN FROM HIGHS IN THE 70S AND 80S ON WEDNESDAY. HIGHS BY THE WEEKEND WILL BE MAINLY IN THE 60S WITH LOWS DIPPING INTO THE 40S. THESE VALUES WILL BE SOME 10 TO 15 DEGREES BELOW NORMAL FOR EARLY SEPTEMBER. && .AVIATION /21Z SATURDAY THROUGH THURSDAY/... STRATUS DECK NORTHWEST OF THE COLD FROPA THIS AFTERNOON WILL BE IFR AT FIRST AND THEN LIFT TO MVFR WITH AN INCREASED CHANCE FOR SOME PASSING SHOWERS. ACTIVITY WILL MOVE SOUTHEAST THROUGH THE DAY AND WITH DAYTIME HEATING SOME THUNDERSTORMS MAY BEGIN TO POP...GENERALLY SOUTHEAST OF I-71 CORRIDOR AND AWAY FROM TAF SITES. CLOUD COVER WILL LIFT AND DISPERSE LATER TODAY UNDER A DRYING NORTH WIND. SKIES WILL CLEAR TONIGHT THOUGH ENOUGH LOW LEVEL MOISTURE MAY BE PRESENT FOR SOME PASSING SC AND DAYBREAK MVFR VSBYS IN FOG. ANY SC TONIGHT IS NOT EXPECTED TO BE EXPANSIVE OR UNIFORM ENOUGH TO MAKE A CIG. OUTLOOK...THUNDERSTORMS ARE POSSIBLE WEDNESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...HATZOS SHORT TERM...HATZOS LONG TERM...HICKMAN AVIATION...FRANKS
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
414 PM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL CONTINUE MOVING THROUGH THE AREA TODAY. DRIER HIGH PRESSURE WILL BUILD IN FOR SUNDAY AND MONDAY...BEFORE WARMER AND MORE HUMID CONDITIONS RETURN ON TUESDAY AND WEDNESDAY. CHANCES FOR SHOWERS AND THUNDERSTORMS WILL INCREASE BY THE MIDDLE OF THE WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... A CURRENT WIND ANALYSIS AT THE SURFACE SHOWS THAT THE COLD FRONT HAS CROSSED THROUGH THE VAST MAJORITY OF THE CWA...WITH NORTHWEST WINDS NOW REPORTED AT PORTSMOUTH AND FLEMING-MASON AIRPORTS. THE AIR MASS CHANGE WILL CONTINUE FOR THE NEXT SEVERAL HOURS...AS TEMPERATURES AND DEWPOINTS ARE STILL MUCH HIGHER IN THE SOUTHEASTERN CWA. NORTH OF THE BROKEN BAND OF LIGHT SHOWERS ACROSS THE HEART OF THE CWA...TEMPERATURES ARE ALREADY FALLING INTO THE UPPER 60S...WITH DEWPOINTS IN THE LOWER TO MID 60S. WITH LAPS ANALYSIS INDICATING SURFACE-BASED INSTABILITY OF AROUND 1000-1500 J/KG IN THE FAR SOUTHERN CWA...THERE STILL REMAINS A BRIEF CHANCE FOR THUNDER. HOWEVER...THE COLD ADVECTION WILL BRING THIS INSTABILITY TO AN END BY AROUND 21Z...WITH ONLY SHOWERS EXPECTED AFTER THAT. HRRR TRENDS INDICATE THAT THE SHOWERS OVER THE REST OF THE CWA WILL CONTINUE A DIMINISHING TREND THIS AFTERNOON AND EVENING...AND THE ENTIRE CWA WILL LIKELY BE DRY BY MIDNIGHT. SKIES ARE ALSO EXPECTED TO CLEAR...BUT THE FALLING DEWPOINTS WILL MAKE FOG UNLIKELY. THESE DRIER CONDITIONS MAY LEAD TO A BIG CHANGE IN MIN TEMPS FROM LAST NIGHT...WITH OUTLYING AREAS IN THE NORTHERN HALF OF THE CWA GETTING AS LOW AS 50 DEGREES TONIGHT. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... SPRAWLING HIGH PRESSURE WILL BE CENTERED OVER THE NORTHERN OHIO VALLEY ON SUNDAY MORNING...WITH A TREND TOWARD GRADUALLY DRIFTING EASTWARD THROUGH MONDAY MORNING. THE DRY AIR MASS WILL KEEP SIGNIFICANT MOISTURE SOUTH OF THE ILN CWA...LIMITING CLOUDS TO JUST A FEW CUMULUS. TEMPERATURES WILL STRUGGLE TO REACH NORMAL VALUES...AND THE GOING FORECAST FOR MAX TEMPS ON SUNDAY IS A FEW DEGREES BELOW CLIMATOLOGY. BY MONDAY MORNING...THE MAIN AXIS OF THE SURFACE HIGH WILL EXTEND FROM UPSTATE NEW YORK THROUGH MISSOURI. AN AREA OF SURFACE TROUGHING IS FORECAST TO DEVELOP ON THE WEST SIDE OF THE APPALACHIANS...AS A WEAK SHORTWAVE ALSO PASSES EASTWARD INTO THE OHIO VALLEY. THOUGH SIGNIFICANT MOISTURE ASSOCIATED WITH A SURFACE LOW WILL AFFECT THE ATLANTIC COAST FROM FLORIDA THROUGH DELAWARE...VERY LITTLE OF THE MOISTURE WILL BE DRAWN AS FAR WEST AS THE ILN CWA. THIS FEATURE WARRANTS ONLY A 20-POP GIVEN CURRENT MODEL PROJECTIONS. FORECAST MAX TEMPERATURES FOR MONDAY ARE VERY CLOSE TO CLIMATOLOGY. WITH A SLIGHT INCREASE IN WARM ADVECTION BEGINNING ON MONDAY NIGHT...MIN TEMPS GOING INTO TUESDAY MORNING REPRESENT AN INCREASE FROM BOTH SATURDAY AND SUNDAY NIGHTS. && .LONG TERM /TUESDAY THROUGH SATURDAY/... THE OPERATIONAL MODELS ARE IN FAIRLY GOOD AGREEMENT FOR THE LONG TERM PERIOD IN TERMS OF LARGE SCALE SYNOPTIC SYSTEMS. THERE ARE THE USUAL STRENGTH AND TIMING ISSUES. AS SUCH...HAVE LEANED ON A BLEND OF THE 12Z ECMWF...12Z GFS AND WPC GUIDANCE. ON TUESDAY...REGION WILL BE UNDER A ZONAL FLOW ALOFT. MODELS INDICATE THAT THERE SHOULD BE A DRY WEDGE IN TERMS OF DEEP MOISTURE AND A LACK OF INSTABILITY...SO HAVE KEPT THE FORECAST DRY DESPITE WEAK EMBEDDED DISTURBANCES WITHIN THE FLOW. SKIES WILL RANGE FROM MOSTLY SUNNY TO PARTLY CLOUDY. HIGHS WILL RANGE FROM THE THE LOWER TO MID 80S. THE UPR LVL FLOW PATTERN WILL UNDERGO AMPLIFICATION THROUGH THE REMAINDER OF THE LONG TERM PERIOD. ENERGY FROM OFF THE CA COAST WILL EJECT QUICKLY NE INTO THE PLAINS AND THEN TO THE WESTERN GREAT LAKES LATE TUESDAY NIGHT INTO WEDNESDAY. THIS ENERGY WILL TRY TO PHASE WITH ENERGY DIGGING FROM WESTERN CANADA INTO THE NORTHERN PLAINS WEDNESDAY INTO THURSDAY. THIS SCENARIO WILL ALLOW A LOW PRESSURE SYSTEM TO DEEPEN AS IT MOVES NORTHEAST THROUGH THE WESTERN GREAT LAKES INTO SE CANADA DURING THIS PERIOD...SENDING AN ATTENDANT COLD FRONT SOUTHEAST THROUGH OUR REGION. CURRENT FORECASTS SUGGEST THAT A STRONG LOW LEVEL JET AND WAA PCPN WILL BREAK OUT TO OUR WEST AND LIKELY SKIM OUR NW CWFA ON WEDNESDAY WITH THE REMAINDER OF THE REGION SEEING A CHANCE OF PCPN WITH AN ADVANCING WARM FRONT. THE BEST THREAT FOR THE ENTIRE REGION TO SEE PCPN WILL COME WEDNESDAY NIGHT INTO THURSDAY MORNING AS THE COLD FRONT SWINGS SOUTHEAST. THIS WILL BE A DYNAMIC SYSTEM WITH DECENT WIND ENERGY AND LOW LEVEL FRONTAL CONVERGENCE. AS SUCH...THE POTENTIAL FOR THUNDERSTORMS TO BE SEVERE WEDNESDAY NIGHT INTO THURSDAY MORNING WILL DEPEND ON THE DEGREE OF INSTABILITY...ALTHOUGH WITH WINDS OF LOWER 40 KNOTS AT 925 MB AND LOWER TO MID 50 KNOTS AT 850 MB...IT MAY NOT TAKE A WHOLE LOT. SPC HAS HIGHLIGHTED THE GREAT LAKES REGION/PARTS OF THE OHIO VALLEY IN A DAY 4 30 PERCENT RISK FOR SEVERE STORMS. WILL HIGHLIGHT THIS THREAT IN THE HWO...BUT WILL BROAD BRUSH IT AT THIS POINT IN TIME. COLD FRONT SHOULD PUSH SOUTHEAST AWAY FROM THE AREA ON THURSDAY WITH PCPN PUSHING OUT AS WELL. FOR THE PERIOD THURSDAY NIGHT INTO SATURDAY...A PRETTY DECENT MID LEVEL CLOSED LOW WILL TRAVERSE EAST/NORTHEAST THROUGH THE GREAT LAKES AND SOUTHEAST CANADA THROUGH THE PERIOD. THIS WILL EVENTUALLY ALLOW AN EXPANSIVE AREA OF SURFACE HIGH PRESSURE TO BUILD INTO THE REGION BY SATURDAY. ANY SPOTTY SHOWER ACTIVITY APPEARS TO BE RELEGATED CLOSER TO THE GREAT LAKES ON FRIDAY SO HAVE LEFT THE FORECAST DRY. TEMPERATURES WILL SHOW A SUBSTANTIAL COOL DOWN FROM HIGHS IN THE 70S AND 80S ON WEDNESDAY. HIGHS BY THE WEEKEND WILL BE MAINLY IN THE 60S WITH LOWS DIPPING INTO THE 40S. THESE VALUES WILL BE SOME 10 TO 15 DEGREES BELOW NORMAL FOR EARLY SEPTEMBER. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... STRATUS DECK NORTHWEST OF THE COLD FROPA THIS AFTERNOON WILL BE IFR AT FIRST AND THEN LIFT TO MVFR WITH AN INCREASED CHANCE FOR SOME PASSING SHOWERS. ACTIVITY WILL MOVE SOUTHEAST THROUGH THE DAY AND WITH DAYTIME HEATING SOME THUNDERSTORMS MAY BEGIN TO POP...GENERALLY SOUTHEAST OF I-71 CORRIDOR AND AWAY FROM TAF SITES. CLOUD COVER WILL LIFT AND DISPERSE LATER TODAY UNDER A DRYING NORTH WIND. SKIES WILL CLEAR TONIGHT THOUGH ENOUGH LOW LEVEL MOISTURE MAY BE PRESENT FOR SOME PASSING SC AND DAYBREAK MVFR VSBYS IN FOG. ANY SC TONIGHT IS NOT EXPECTED TO BE EXPANSIVE OR UNIFORM ENOUGH TO MAKE A CIG. OUTLOOK...THUNDERSTORMS ARE POSSIBLE WEDNESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...HATZOS SHORT TERM...HATZOS LONG TERM...HICKMAN AVIATION...FRANKS
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
329 PM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL MOVE SOUTHEAST OF THE COMMONWEALTH LATE TONIGHT...BRINGING LOCALLY STRONG STORMS AND USHERING MUCH DRIER AIR INTO CENTRAL AND SOUTHEASTERN PORTIONS OF PENNSYLVANIA. HIGH PRESSURE OVER THE MIDWEST WILL THEN SLIDE ACROSS PENNSYLVANIA SUNDAY INTO EARLY NEXT WEEK...AS A WEAK LOW PRESSURE SYSTEM TRACKS SOUTH OF PENNSYLVANIA AND OFF THE MID ATLANTIC COAST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... STORMS POPPING IN THE AREA OF MAX SFC HEATING FROM LEBANON AND LANCASTER COUNTIES WESTWARD TO THE LAUREL HIGHLANDS AT MID AFTERNOON. STORMS ARE MARGINAL...WITH PLENTIFUL CAPE TO INITIATE BUT LESS THAN MARGINAL SHEAR FOR MAINTENANCE...INTENSIFICATION OR LONGEVITY. HAVE JUST RECEIVED ONE SMALL MARBLE SIZED HAIL REPORT FROM LEBANON COUNTY...AND KNOW THAT EXISTING STORMS ARE PRODUCING BRIEF HEAVY DOWNPOURS...BUT STORM MOTION IS PRECLUDING ANY FLOODING THREATS AS ANTICIPATED. LATEST HRRR INDICATES THAT THE SOUTHERN ONE QUARTER TO ONE THIRD OF CENTRAL PA IS THE MAIN SEVERE THREAT THROUGH LATE AFTERNOON... WITH THE LOWER SUSQ MOST SUSCEPTIBLE TO ISOLATED SEVERE IN THE FORM OF DAMAGING WIND GUSTS OR LARGE HAIL. COLD FRONT EVIDENT IN SFC OBS FROM NEAR KDUJ NORTHEASTWARD TO 10S KELM AT THIS HOUR... AND A NARROW CONVECTIVE RAINBAND HAS DEVELOPED ALONG IT. TO THE WEST AND NORTH...PLAIN SHOWER ACTIVITY IS OCCURRING OVER THE NORTHWEST MOUNTAINS...AND DEWPOINTS HAVE DROPPED TO THE MIDDLE 50S ACROSS WARREN AND MCKEAN COUNTIES. SUCCESSIVE UPDATES HAVE DECREASED POPS OVERALL AS CONVECTION AND THUNDERSTORM THREAT IN PARTICULAR DID NOT MATERIALIZE NORTH OF I80. A PERIOD OF SHOWERS WILL AFFECT THE NORTHWEST THROUGH LATE AFTERNOON BEFORE DRIER AIR AND CLEARING ARRIVE THIS EVENING. TO THE SOUTH...WILL CONTINUE TO MONITOR FOR ISOLATED SEVERE... WITH AGAIN THE MAIN THREAT THE SOUTH CENTRAL MOUNTAINS THROUGH THE LOWER SUSQ RIVER VALELY. EVENING SHRA/TSRA ACROSS THE CENTRAL AND SE COUNTIES WILL GIVE WAY TO CLEARING SKIES LATE TONIGHT...AS COLD FRONT SETTLES SOUTH OF THE STATE AND HIGH PRES/LOW PWAT AIR WORKS IN FROM THE WEST. THE CLEARING SKIES AND LGT WIND SHOULD PROMOTE AREAS OF LATE NIGHT FOG IN THE VALLEYS OF WESTERN PA. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... SUNDAY WILL FEATURE INCREASINGLY DRIER AIR MASS...AND PLENTY OF SUNSHINE AFTER EARLY MORNING FOG DISSIPATES. A MUCH MORE COMFORTABLE DAY WITH MUCH LESS HUMID AIR MASS WILL BRING AN ENJOYABLE CLOSE TO THE WEEKEND AS HIGH PRES PASSES NORTH OF PA. MAXES WILL RANGE FROM THE UPPER 60S NORTH TO THE UPPER 70S OVER THE LOWER SUSQ RIVER VALLEY. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... FRONT DROPPING SE THIS AFT WILL BRING MUCH LESS HUMID AIR TO THE AREA. QUESTION IS HOW FAR NORTH MOISTURE WILL MAKE IT ON MONDAY INTO TUE...AS SYSTEM ACROSS THE SE LIFTS NE. MID SHIFT HAD SOME CHC IN FOR MONDAY ALREADY. MINOR ADJUSTMENTS. DID EDGE TEMPS UP SOME. THE BIG STORY IS THE COMPLEX LOW FOR THE PLAINS FOR MID WEEK. THE 00Z 09/06 RUN HAS THIS SYSTEM TRACKING MUCH FURTHER NW THAN THE EARLIER RUN. THUS TREND IS MOST LIKELY FOR COLD AIR TO COME IN SLOWER...AND FIRST BATCH OF COLD AIR NOT TO BE VERY DEEP. UPPER LVL TROUGH MAY TRY TO DEEPEN THE COLD AIR MORE LATER IN THE WEEK. MINOR ADJUSTMENTS MADE. ALSO AS UPPER LVL SYSTEM SHEARS...HARD TO SEE MUCH ACTION OFF LAKES IN OUR AREA. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... COLD FRONT WILL SLIDE SE ACROSS THE CENTRAL AND SOUTHEAST PORTIONS OF CENTRAL PA THROUGH THE EARLY EVENING HOURS. KEPT VCTS TO IN ALL TAFS EXCEPT KBFD FOR SEVERAL HOURS THIS AFTERNOON...WITH LOCAL RESTRICTIONS ARE LIKELY IN HEAVIER SHOWERS/TSTMS. FROPA MAY BRING ANOTHER BAND OF SHOWERS BEFORE ACTIVITY TAPERS OFF THIS EVENING. CONDITIONS IMPROVE BEHIND THE FRONT...THOUGH MVFR CIGS COULD LINGER WELL INTO THE EVENING IN THE WESTERN HIGHER TERRAIN. CLEARING SKIES AND TRAPPED MOISTURE COULD BRING REDUCTIONS TO CIGS/VSBYS LATER TONIGHT INTO SUNDAY MORNING. OUTLOOK... SUN...AM FOG POSS. MON...PATCHY AM VALLEY FOG POSS. TUE...CHC SHOWERS/TSTMS. WED...SCT SHOWERS/TSTMS. THU...SCT SHOWERS/TSTMS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DEVOIR NEAR TERM...DEVOIR SHORT TERM...DEVOIR LONG TERM...MARTIN AVIATION...DEVOIR
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
239 PM EDT SAT SEP 6 2014 .SYNOPSIS... A COLD FRONT WILL MOVE SOUTHEAST OF THE COMMONWEALTH LATE TONIGHT...BRINGING LOCALLY STRONG STORMS AND USHERING MUCH DRIER AIR INTO CENTRAL AND SOUTHEASTERN PORTIONS OF PENNSYLVANIA. HIGH PRESSURE OVER THE MIDWEST WILL THEN SLIDE ACROSS PENNSYLVANIA SUNDAY INTO EARLY NEXT WEEK...AS A WEAK LOW PRESSURE SYSTEM TRACKS SOUTH OF PENNSYLVANIA AND OFF THE MID ATLANTIC COAST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... STORMS POPPING IN THE AREA OF MAX SFC HEATING FROM LEBANON AND LANCASTER COUNTIES WESTWARD TO THE LAUREL HIGHLANDS AT MID AFTERNOON. STORMS ARE MARGINAL...WITH PLENTIFUL CAPE TO INITIATE BUT LESS THAN MARGINAL SHEAR FOR MAINTENANCE...INTENSIFICATION OR LONGEVITY. HAVE JUST RECEIVED ONE SMALL MARBLE SIZED HAIL REPORT FROM LEBANON COUNTY...AND KNOW THAT EXISTING STORMS ARE PRODUCING BRIEF HEAVY DOWNPOURS...BUT STORM MOTION IS PRECLUDING ANY FLOODING THREATS AS ANTICIPATED. LATEST HRRR INDICATES THAT THE SOUTHERN ONE QUARTER TO ONE THIRD OF CENTRAL PA IS THE MAIN SEVERE THREAT THROUGH LATE AFTERNOON... WITH THE LOWER SUSQ MOST SUSCEPTIBLE TO ISOLATED SEVERE IN THE FORM OF DAMAGING WIND GUSTS OR LARGE HAIL. COLD FRONT EVIDENT IN SFC OBS FROM NEAR KDUJ NORTHEASTWARD TO 10S KELM AT THIS HOUR... AND A NARROW CONVECTIVE RAINBAND HAS DEVELOPED ALONG IT. TO THE WEST AND NORTH...PLAIN SHOWER ACTIVITY IS OCCURRING OVER THE NORTHWEST MOUNTAINS...AND DEWPOINTS HAVE DROPPED TO THE MIDDLE 50S ACROSS WARREN AND MCKEAN COUNTIES. SUCCESSIVE UPDATES HAVE DECREASED POPS OVERALL AS CONVECTION AND THUNDERSTORM THREAT IN PARTICULAR DID NOT MATERIALIZE NORTH OF I80. A PERIOD OF SHOWERS WILL AFFECT THE NORTHWEST THROUGH LATE AFTERNOON BEFORE DRIER AIR AND CLEARING ARRIVE THIS EVENING. TO THE SOUTH...WILL CONTINUE TO MONITOR FOR ISOLATED SEVERE... WITH AGAIN THE MAIN THREAT THE SOUTH CENTRAL MOUNTAINS THROUGH THE LOWER SUSQ RIVER VALELY. EVENING SHRA/TSRA ACROSS THE CENTRAL AND SE COUNTIES WILL GIVE WAY TO CLEARING SKIES LATE TONIGHT...AS COLD FRONT SETTLES SOUTH OF THE STATE AND HIGH PRES/LOW PWAT AIR WORKS IN FROM THE WEST. THE CLEARING SKIES AND LGT WIND SHOULD PROMOTE AREAS OF LATE NIGHT FOG IN THE VALLEYS OF WESTERN PA. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... SUNDAY WILL FEATURE INCREASINGLY DRIER AIR MASS...AND PLENTY OF SUNSHINE AFTER EARLY MORNING FOG DISSIPATES. A MUCH MORE COMFORTABLE DAY WITH MUCH LESS HUMID AIR MASS WILL BRING AN ENJOYABLE CLOSE TO THE WEEKEND AS HIGH PRES PASSES NORTH OF PA. MAXES WILL RANGE FROM THE UPPER 60S NORTH TO THE UPPER 70S OVER THE LOWER SUSQ RIVER VALLEY. && .LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/... BULK OF MED RANGE GUIDANCE INDICATES A CLOUDIER AND PERHAPS SHOWERY MON/TUE THAN WAS EARLIER THOUGHT...AS SHORTWAVE AND ASSOC WEAK WAVE OF LOW PRES SLIDES JUST SOUTH OF PA. TIMING OF THIS FEATURE IN GEFS OUTPUT SUGGESTS THE BEST CHANCE FOR A FEW -SHRA WILL COME LATE MONDAY INTO EARLY TUESDAY ACROSS SOUTHERN PA. FAIRLY GOOD AGREEMENT LATE WEEK AMONGST MED RANGE MDLS...ALL OF WHICH TRACK A DEEPENING SFC LOW WEST OF PA THRU THE GRT LKS. TRAILING COLD FRONT AND ASSOC SHOWER THREAT IS LIKELY TO COME THRU CENTRAL PA THURSDAY. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... COLD FRONT WILL SLIDE SE ACROSS THE CENTRAL AND SOUTHEAST PORTIONS OF CENTRAL PA THROUGH THE EARLY EVENING HOURS. KEPT VCTS TO IN ALL TAFS EXCEPT KBFD FOR SEVERAL HOURS THIS AFTERNOON...WITH LOCAL RESTRICTIONS ARE LIKELY IN HEAVIER SHOWERS/TSTMS. FROPA MAY BRING ANOTHER BAND OF SHOWERS BEFORE ACTIVITY TAPERS OFF THIS EVENING. CONDITIONS IMPROVE BEHIND THE FRONT...THOUGH MVFR CIGS COULD LINGER WELL INTO THE EVENING IN THE WESTERN HIGHER TERRAIN. CLEARING SKIES AND TRAPPED MOISTURE COULD BRING REDUCTIONS TO CIGS/VSBYS LATER TONIGHT INTO SUNDAY MORNING. OUTLOOK... SUN...AM FOG POSS. MON...PATCHY AM VALLEY FOG POSS. TUE...CHC SHOWERS/TSTMS. WED...SCT SHOWERS/TSTMS. THU...SCT SHOWERS/TSTMS. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DEVOIR NEAR TERM...DEVOIR SHORT TERM...DEVOIR LONG TERM...FITZGERALD/GARTNER AVIATION...DEVOIR
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
330 PM CDT SAT SEP 6 2014 .DISCUSSION... COLD FRONT LOCATED JUST SOUTH OF A BOWLING GREEN...CLARKSVILLE TO DYERSBURG LINE. SCATTERED ACTIVITY IS ORIENTED IN NEARLY LINEAR FASHION SW-NE ACROSS THE MID STATE. THE ACTIVITY IS MOVING RATHER SLOWLY TOWARD THE SOUTH SOUTHEAST. MID LEVEL FLOW IS RATHER UNPRONOUNCED AS THE WESTERLIES HAVE NOT YET FULLY DESCENDED SOUTHWARD ACROSS THE AREA. AT ANY RATE...LATEST HRRR SHOWS THAT THE CURRENT ACTIVITY WILL HOLD TOGETHER THROUGH THIS EVENING AS IT MOVES ACROSS SOUTHERN AREAS OF THE MID STATE. THEN LATER TONIGHT...AN IMPULSE WITHIN THE WESTERLY FLOW WILL MOVE TOWARD THE AREA AND WE COULD SEE SOME ADDITIONAL DEVELOPMENT. POPS FOR TONIGHT ARE LOOKING LIKE 30-40 PERCENT SOUTH AND 20 PERCENT ACROSS THE NORTH. COULD SEE SOME LATE NIGHT PATCHY FOG DEVELOPMENT ACROSS EASTERN AREAS. DEWPOINT DEPRESSIONS SHOULD REMAIN RATHER LOW ACROSS THAT AREA. ON SUNDAY...JUST ENOUGH MOISTURE WILL HANG ON ACROSS THE PLATEAU TO WARRANT A SLIGHTLY CHANCE OF SHOWERS. OTW...DRIER AIR TO MOVE IN WITH NO PRECIP EXPECTED. SUNDAY NIGHT AND MONDAY NIGHT LOOK DRY AND COOLER. THE CLOSE PROXIMITY OF THE SFC HIGH CLOSE NEVER REALLY CLOSES IN ON THE MID STATE. HOWEVER...IT DOES LOOK LIKE LOWER 60S TO UPPER 50S FOR LOWS. MONDAY WILL FEATURE A MOSTLY SUNNY AND DRY DAY. SHOULD STILL SEE HIGHS IN THE MID TO UPPER 80S AS THE UPPER TROUGHING IS RATHER BROAD AND HEIGHTS STILL LOOK ELEVATED. IN THE EXTENDED FCST...A COLD FRONT WILL GAIN STRENGTH AND WILL BE ON APPROACH BY WEDNESDAY NIGHT. SHOULD SEE A NICE WARMUP IN ADVANCE OF IT WITH HIGHS TUESDAY AND WEDNESDAY IN THE LOWER 90S. SHOWERS AND TSTMS WILL BE A GOOD POSSIBILITY ON THURSDAY...A FEW STRONG STORMS WILL BE POSSIBLE ALTHOUGH CAPE VALUES LOOK RATHER TEMPERED NOW. SHOWER CHANCES TO PERSIST IN THE POST FRONTAL SECTOR AS THE LOWER LEVELS FEATURE A REASONABLE SFC TO 850 MB HORIZONTAL FRONTAL BOUNDARY DISPLACEMENT. WE SHOULD RETURN TO DRIER AND NOTICEABLY COOLER WEATHER FOR FRIDAY AND SATURDAY. THE FRONTAL BOUNDARY WILL STALL JUST NORTH OF THE GULF COAST AS UPPER LEVEL W-E RIDGING STUBBORNLY HOLDS ACROSS THAT AREA. BY THE END OF THE EXTENDED...WE SHOULD SEE PLEASANT EARLY FALL WEATHER WITH LOWS UPPER 40S TO LOWER 50S AND HIGHS JUST 70 TO 75 WITH LOW HUMIDITY. && .PRELIMINARY POINT TEMPS/POPS... NASHVILLE 68 85 63 88 / 30 10 10 10 CLARKSVILLE 64 83 58 86 / 20 10 10 05 CROSSVILLE 66 80 60 83 / 30 20 10 10 COLUMBIA 68 86 64 89 / 30 10 10 05 LAWRENCEBURG 67 86 64 89 / 30 20 10 05 WAVERLY 66 84 60 87 / 20 10 10 05 && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 21
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
228 PM EDT SAT SEP 6 2014 .SYNOPSIS... A STRONG COLD FRONT WILL PUSH THROUGH OUR AREA TODAY AND TONIGHT...HELPING TO IGNITE SCATTERED TO NUMEROUS SHOWERS AND STORMS. THIS FRONT WILL STALL SOUTH OF THE REGION THROUGH EARLY NEXT WEEK...KEEPING CLOUDS ALONG WITH THE THREAT FOR SHOWERS...BUT COOLER TEMPERATURES. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1130 AM EDT SATURDAY... BROAD CYCLONIC UPPER LEVEL FLOW EXISTS FROM HUDSON BAY REGION OF CANADA SOUTHWARD INTO THE GREAT LAKES AND NEW ENGLAND. EMBEDDED SHORT WAVE TROF WILL MOVE EAST FROM ONTARIO INTO QUEBEC TODAY WITH RIBBON OF VORTICITY TRAILING SOUTHWEST THROUGH THE GREAT LAKES AND INTO THE OHIO VALLEY. AT THE SURFACE A COLD FRONT EXTENDED FROM LAKE ONTARIO...SOUTHWEST THROUGH THE OHIO VALLEY AND INTO THE MID SECTION OF THE COUNTRY...SURFACE HIGH PRESSURE REPLACING AREAS UPSTREAM OF THE FRONT WITH A MUCH COOLER DRIER AIRMASS...DEWPOINTS IN THE 50S. EAST AND SOUTH OF THE FRONTAL BOUNDARY THE AIRMASS WAS MORE TROPICAL LIKE WITH SURFACE DEWPOINTS IN THE LOWER 70S AND DEEPER MOISTURE PROFILES SUPPORTING PERCEPTIBLE WATER...PWAT... VALUES BETWEEN 1.6 AND 2.0 INCHES. THE SURFACE COLD FRONT IS PROGGED TO ADVANCE SOUTH AND EAST TODAY...APPROACHING OUR FORECAST AREA LATE IN THE DAY...BUT NOT ACTUALLY CROSSING THE FORECAST AREA AND PROVIDING ANY SORT OF AIRMASS CHANGE UNTIL LATE TONIGHT AND SUNDAY. UNTIL THE FRONT CROSSES THE AREA WE WILL CONTINUE TO BASK IN THE TROPICAL AIRMASS WITH MUGGY CONDITIONS PERSISTING THROUGHOUT THE DAY...NOT VERY COMFORTABLE FOR OUTDOOR WORK...BUT MORE CONDUCIVE FOR JUST SITTING AROUND IN THE SHADE AND DRINKING ICE TEA. WHATEVER YOUR CHOICE...AT SOME POINT YOU WILL LIKELY HEAR A RUMBLE OF THUNDER. EVEN THOUGH THE COLD FRONT WILL NOT GET HERE UNTIL TONIGHT...THERE IS AN OUTFLOW BOUNDARY FROM LAST NIGHTS STORM ACTIVITY OVER THE OHIO VALLEY THAT IS MOVING SOUTHEAST AHEAD OF THE ACTUAL COLD FRONT. THIS OUTFLOW EXTENDS FROM SOUTHERN PENNSYLVANIA THROUGH CENTRAL WEST VIRGINIA AND INTO EASTERN KENTUCKY THIS MORNING. THIS OUTFLOW WILL LIKELY BECOME THE FOCUS FOR RE-DEVELOPMENT OF STORM ACTIVITY AS IN MOVES ACROSS THE MOUNTAINS THIS AFTERNOON. NONE OF THE MODELS HANDLE THIS FEATURE VERY WELL...BUT I THINK THE NAM PROBABLY HAS THE BEST PROGNOSIS WITH DEEP COVECTION FIRING ALONG THIS BOUNDARY AS IT CROSSES THE HIGHLANDS OF WV/VA EARLY THIS AFTERNOON...ACTIVITY BECOMING MORE AGGRESSIVE AND INCREASE IN AREAL COVERAGE ALONG THE BOUNDARY AS WE APPROACH THE PEAK HEATING PART OF THE DAY. THE MORNING RNK SOUNDING WAS QUITE JUICY WITH PWAT VALUES OF 1.72 INCHES. CAPE WAS AROUND 1200 J/KG INCREASING TO 2000 WHEN WE REACH A COVECTIVE TEMPERATURE IN THE LOWER 80S. MEAN WIND WAS FROM 260 AT ABOUT 12KTS...AND PROGGED TO INCREASE SLIGHTLY AS THE UPPER LEVEL WINDS INCREASE PER THE APPROACHING UPPER LEVEL TROF. GIVEN THIS VERY MOIST PROFILE AND LESS THAN MODEST WIND FLOW...THINK OUR MAIN THREAT THIS AFTERNOON WILL BE THUNDERSTORMS CONTAINING VERY HEAVY RAIN. WINDS ALOFT SHOULD KEEP THE STORMS MOVING ALONG AT A GOOD ENOUGH PACE TO PREVENT NEED FOR A FLASH FLOOD WATCH...HOWEVER A LITTLE CONCERNED THAT OUR SOUTHWESTERN CWA...FROM THE FAR WESTERN NEW RIVER VALLEY INTO NORTHWEST NORTH CAROLINA MAY BE AN AREA WHERE WINDS WILL BE A FEW KNOTS LIGHTER. STORMS IN THIS PARTICULAR REGION WILL NOT ONLY BE MOVING SLOWER...BUT MAY HAVE A TENDENCY TO TRAIN OVER THE SAME AREA PER THE OUTFLOW BOUNDARY BECOMING MORE WEST-EAST ORIENTED. IF RADAR TRENDS BEGIN TO REFLECT THIS SORT OF SCENARIO...A SHORT DURATION FLASH FLOOD WATCH MAY BE NEED FOR PARTS OF THE FORECAST AREA. EVEN THOUGH THE MAIN THREAT IS HEAVY RAIN...CAN`T RULE OUT SOME ISOLATED SEVERE WEATHER TOO. THE MORE ROBUST STORMS THIS AFTERNOON MAY TAP INTO A BIT MORE MOMENTUM FROM THE INCREASING WINDS ALOFT. THIS WILL ALSO BE AIDED BY WATER LOADING FROM THE INTENSE RAIN CORES INCREASING POTENTIAL FOR WET MICROBURSTS...SOMETHING WE EXPERIENCED WITH A FEW OF THE STORMS THAT MOVED ACROSS THE AREA LAST TUESDAY EVENING. ATTM WILL MAINTAIN LIKELY THREAT FOR SHOWERS/STORMS WITH HEAVY RAIN...THE GREATEST COVERAGE OVER THE MOUNTAINS THIS AFTERNOON AND TRANSLATING INTO THE PIEDMONT THIS EVENING. TEMPERATURES WILL BE ALL OVER THE PLACE...SPIKING INTO THE 80S...AROUND 90 PRIOR TO SHOWER AND STORM DEVELOPMENT...THEN BECOMING INFLUENCED BY THE THUNDERSTORM RAIN CORES WITH READINGS GETTING KNOCKED BACK INTO THE 70S BEFORE THE END OF THE DAY. DEWPOINTS WILL REMAIN HIGH...U60S/L70S...SO IT WILL REMAIN MUGGY THROUGHOUT THE DAY. BY 12Z SUNDAY...THE SFC FRONT IS FORECAST TO BE IN CENTRAL NC...BUT PRECIPITATION IN THE SOUTHEAST PORTION OF THE FORECAST AREA WILL LIKELY BE SLOW TO END WITH THE SLOW MOVEMENT OF THE FRONT...ALONG WITH GOOD UPPER LEVEL DIVERGENCE ASSOCIATED WITH A RR QUAD OF AN UPPER LEVEL JET MOVING THROUGH THE EASTERN GREAT LAKES AND NEW ENGLAND. LOW CLOUDS AND AND LIGHT PRECIP WELL TO THE NORTH OF THE BOUNDARY WILL BE POSSIBLE AS WEDGE BEGINS TO BUILD PER HIGH PRESSURE MOVING INTO NEW ENGLAND AND THE STABLE AIR TRYING TO WORK ITS WAY DOWN THE EASTERN SEABOARD...A NORTHEAST WIND DEVELOPING ALONG AND EAST OF THE APPALACHIANS. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... AS OF 330 AM EDT SATURDAY... OVERALL LOOKS LIKE A DAMP/WEDGE PATTERN FOR US THIS PERIOD. MODELS ARE DIFFERING ON STRENGTH/POSITION OF A SFC LOW OVER THE SE COAST SUN-TUE...BUT PER TRENDS/WPC GUIDANCE THE 00Z ECMWF/GFS SEEM IN THE BALL PARK ON THIS SYSTEM. DIFFERENCES BETWEEN THESE MODELS LIES IN THE QPF FIELD. THE GFS SEEMS INLAND TOO MUCH WITH QPF MONDAY...THINKING A LOT OF DEEP MOISTURE WILL RESIDE ACROSS THE COASTLINE WITH CONVECTION AND HENCE ROB SOME INFLOW INTO OUR NECK OF THE WOODS. FOR SUNDAY...THE SFC LOW WILL BE OVER GEORGIA/SOUTH CAROLINA WHILE SFC HIGH STRETCHES FROM IA/MO ENE INTO WRN PA/NY. THE FLOW WILL TURN MORE NE-E WITH INCREASING MOISTURE. SFC FRONT WILL BE SOUTHEAST OF US ACROSS ERN NC...BUT SW FLOW ALOFT COMBINED WITH EASTERLY FLOW WILL KEEP MOISTURE INFLOW INTO OUR REGION WITH HIGHER THREAT ALONG THE SRN BLUE RIDGE SUNDAY AFTERNOON. THE SFC HIGH MOVES QUICKLY NE AND SETS UP OVER NEW ENGLAND/SRN QUEBEC SUNDAY NIGHT WITH FRONTAL SYSTEM REMAINING ALONG THE COAST...WITH INVERTED TROUGH IN ERN TN. FAVORING A BETTER THREAT OF SHOWERS EAST OF THE BLUE RIDGE SUNDAY NIGHT OVER INTO MONDAY NIGHT...AS THE LOW SLIDES SLOWLY NWD ACROSS ERN NC THEN OFF THE VA COAST. THE MODELS START TO SHOW DRIER AIR WORKING IN FROM THE WEST TUESDAY MORNING...WITH DEEP MOISTURE SHIFTING OUT TO SEA. TUESDAY WILL BE A DRIER DAY BUT MODELS SHOWING ANOTHER SYSTEM MOVING INTO THE SRN PLAINS WITH UPPER SHORTWAVE SHIFTING ALONG THE NRN EDGE OF THE RIDGE THAT REMAINS OVER THE GULF COAST INTO OUR REGION. ATTM...NOT TOO IMPRESSED WITH PRECIP CHANCES TUESDAY WITH MAINLY AFTERNOON/EVENING SHOWERS AND STORMS SCATTERED ACROSS THE BLUE RIDGE AND ADJACENT COUNTIES WEST INTO THE WV MOUNTAINS. TEMPS THIS PERIOD REMAIN TRICKY BUT WILL MOS SEEMS TO HAVE A DECENT HANDLE ON HIGHS. SUNDAY WILL BE TRANSITION DAY...BUT WILL SEE HIGHS MAINLY IN THE 70S BEHIND THE FRONT WITH NE WINDS. IF PRECIP IS MORE WIDESPREAD HIGHS MONDAY MAY NOT GET OUT OF THE 60S IN THE EAST. FOR NOW I AM LEANING TOWARD THE MAV WHICH HAS HIGHS FROM THE LOWER TO MID 70S IN THE WEST TO UPPER 70S/LOWER 80S ACROSS THE FAR SW CWA...WITH SOME 60S IN BLUE RIDGE HIGHER TERRAIN AS WELL AS THE ALLEGHANYS. TUESDAY WILL BE WARMER WITH FLOW WEAKENING AND TURNING MORE NNW. HIGHS WILL RANGE FROM THE MID TO UPPER 70S WEST TO LOWER 80S SOUTHEAST. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... AS OF 400 PM EDT FRIDAY... ON WEDNESDAY...A COLD FRONT SWEEPS ACROSS THE NORTHERN PLAINS WITH A SURFACE WAVE TRACKING NORTHEAST TOWARDS THE GREAT LAKES. AS THIS WAVE MOVES INTO ZONAL FLOW...IT WILL THEN TRACK OVER THE OHIO VALLEY WEDNESDAY AFTERNOON/EVENING. THIS WAVE WILL KEEP BULK OF THE STRONGER CONVECTION NORTH IN THE OHIO VALLEY. AS THIS WAVE ENTERS THE OHIO VALLEY...THE WEDGE THAT WAS OVER THE MID ATLANTIC REGION MONDAY AND TUESDAY WILL BEGIN TO ERODE. IF THIS WEDGE REMAINS DRY WHILE IN THE AREA...IT SHOULD HAVE NO PROBLEMS ERODING WEDNESDAY. IF THIS WEDGE HAS RAIN TO ENHANCE IT...IT MAY NOT CLEAR THE AREA UNTIL LATE WEDNESDAY NIGHT. MODELS ARE PUSHING THIS COLD FRONT ACROSS THE REGION ON THURSDAY. AS IN THE CASE WITH THE FRONT EARLY IN THE WEEK...DOES THIS FRONT CLEAR THE FORECAST AREA OR DOES IT STALL IN THE VICINITY. SINCE THIS FRONT IS TRYING TO TRACK SOUTH IN ZONAL FLOW...THE POSSIBILITIES OF A SLOWER ARRIVAL (FRIDAY AND/OR SATURDAY) OR HAVING THE FRONT STALL OVER THE REGION IS HIGH. SINCE THIS IS POSSIBLE...WILL KEEP CHANCE POPS IN FOR FRIDAY. AREAS THAT HANG ON TO THE WEDGE WEDNESDAY WILL HAVE COOLER THAN NORMAL TEMPERATURES. IF OUTSIDE THE WEDGE...AT OR ABOVE NORMAL TEMPERATURES ARE LIKELY. THE WARMEST DAY OF THE WEEK SHOULD BE THURSDAY...ESPECIALLY IF THE FRONT IS SLOW TO TRACK EAST. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 200 PM EDT SATURDAY... SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS WILL OCCUR ACROSS THE AREA THROUGH 10PM THIS EVENING AS A COLD FRONT SLOWLY CROSSES THE MOUNTAINS. INTENSE RAIN CORES WITH RAIN RATES OF 2-4 INCHES/HR ANITICIPATED RESULTING IN WATER LOADING AND LOCALIZED STRONG DOWNDRAFTS. POTENTIAL EXISTS FOR WET MICROBURST WINDS VCNTY OF STRONGEST STORMS. PASSAGE OF FRONT LATER TONIGHT WILL BRIND A WIND SHIFT...WINDS BECOMING NORTHERLY...THEN NORTHEASTERLY BEHIND THE FRONT FOR SUNDAY. NOT CONFIDENT AS TO HOW MUCH FOG/STRATUS WILL FORM TONIGHT NOR HOW LONG IT WILL LINGER SUNDAY...BUT MODELS ARE SUGGESTING WIDESPREAD IFR CONDITIONS WILL DEVELOP LATE TONIGH AND SUNDAY PER LINGERING LOW LEVEL MOISTURE AND POTENTIAL FOR THIS MOISTURE TO GET ENHANCED BY THE DEVELOPING NORTHEASTERLY WIND AND WEDGE OF STABLE AIR DEVELOPING OVER AND EAST OF THE MOUNTAINS SUNDAY. THE FRONT IS FORECAST TO STALL JUST SOUTH OF THE AREA SUNDAY AND MONDAY...MAINTAINING CLOUD COVER AS WELL AS A THREAT FOR SHOWERS. MEANWHILE LOW PRESSURE MOVING ALONG THE SOUTHEAST COAST WILL KEEP OUR WINDS NE. THIS LOW IS PROGGED TO MOVE NORTHEAST ALONG THE COAST MONDAY...MOVING OUT TO SEA BY LATE TUESDAY. UNTIL THIS AREA OF LOW PRESSURE MOVES WELL OFF SHORE THE EXPECTATION IS FOR LINGERING LOW LEVEL CLOUDINESS. AFTER TUESDAY A RETURN TO SUMMER-LIKE CONDITIONS CAN BE EXPECTED WITH DIURNAL SHOWERS AND STORMS. LATE NIGHT FOG IS ALSO LIKELY IN THE MOUNTAIN VALLEYS. NEXT COLD FRONT IS FORECAST TO MOVE ACROSS THE MIDWEST AND OHIO VALLEY WEDNESDAY WITH STRONG AREA OF LOW PRESSURE MOVING INTO THE GREAT LAKES IMPACTING ROUTES THROUGH DTX- ORD-MSP. THIS FRONT SHOULD REACH THE MID ATLANTIC REGION IN THE THURSDAY/FRIDAY TIME FRAME. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...PH NEAR TERM...PH/PM SHORT TERM...WP LONG TERM...RCS AVIATION...PM