Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/11/12


AREA FORECAST DISCUSSION
NWS NEW YORK NY
542 PM EDT THU AUG 9 2012 .SYNOPSIS... LOW PRESSURE AND A COLD FRONT APPROACH TONIGHT THROUGH FRIDAY. A SECONDARY LOW WILL FORM AND IMPACT THE AREA FRIDAY NIGHT THROUGH SATURDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS A PRE-FRONTAL TROUGH EDGES CLOSER TO WESTERN PORTIONS OF THE CWA...SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP AND TRACK EAST. ML MUCAPE VALUES REMAIN QUITE HIGH...AVERAGING 2000-3000 J/KG OVER THE AREA...BUT MOST OF THE MODELS HAVE THE STORMS BARELY MAKING IT THROUGH NYC BEFORE ENDING JUST AS THEY APPROACH FAIRFIELD AND NASSAU COUNTIES. ONLY THE HRRR MODEL HAS STORMS GOING THROUGH NYC AND INTO WESTERN CT AND LONG ISLAND. STORMS THE DEVELOPED ALONG THE NORTH SHORE OF LONG ISLAND IN ASSOCIATION WITH THE SEA BREEZE BOUNDARY HAVE ENDED...AND DO NOT THINK MUCH ADDITIONAL ACTIVITY WILL OCCUR FROM THAT BOUNDARY. WILL FOLLOW THE GUIDANCE AND KEEP LIKELY POPS CONFINED TO FAR NW ZONES...MAINLY ORANGE/ROCKLAND AND WESTERN PASSAIC COUNTIES...AND HIGH CHANCE ALONG AND WEST OF THE HUDSON RIVER. ONCE STORMS FIRE UP AND TRACK EAST...THEY WILL MOVE INTO AN ATMOSPHERE THAT REMAINS UNSTABLE. MID-LEVEL STEERING CURRENT SEEMS LOW...SO STORMS WILL TRACK FAIRLY SLOWLY. THIS WILL RESULT IN AREAS OF LOCALLY HEAVY RAINFALL...WHICH COULD RESULT IN FLASH FLOODING. AT THE VERY LEAST...URBAN/POOR DRAINAGE/SMALL STREAM FLOODING CAN BE EXPECTED. IN ADDITION...STORMS ARE CAPABLE OF GUSTY WINDS AND FREQUENT AND DANGEROUS LIGHTNING STRIKES. STORMS TAPER OFF BY MIDNIGHT. LOW PRES OVER THE MIDWEST CONTINUES TO MOVE INTO THE OH VALLEY...SO WILL KEEP AT LEAST SLIGHT CHANCE TO LOW CHANCE POPS IN THE FORECAST THROUGH THE OVERNIGHT. WITH ABUNDANT LOW LEVEL MOISTURE IN THE ATMOSPHERE...EXPECTING LOW STRATUS/FOG TO DEVELOP AFTER MIDNIGHT. WARM AND HUMID TONIGHT WITH LOWS IN THE MID 70S IN/AROUND NYC AND IN THE UPPER 60S ELSEWHERE. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... LOW PRES OVER THE GREAT LAKES MOVES INTO THE OH VALLEY FRIDAY AFTERNOON AND INTENSIFIES AS IT THEN TRACKS OVER LAKE HURON. THIS SYSTEM WILL PUSH A WARM FRONT ALONG THE EAST COAST AND THROUGH THE REGION FROM SOUTH TO NORTH DURING THE DAY FRIDAY. AS THIS FRONT TRACKS NORTH...IT WILL HAVE UPPER LEVEL SUPPORT FROM A MID LEVEL SHORTWAVE TRACKING ALONG THE COAST. SHOWERS AND THUNDERSTORMS WILL OVERSPREAD THE REGION FROM SOUTH TO NORTH...AND WITH ELEVATED INSTABILITY OVER THE REGION...GUSTY WINDS AND FREQUENT LIGHTNING CAN BE EXPECTED. A TROPICAL AIRMASS WILL OVERSPREAD THE REGION... MAKING IT VERY WARM AND HUMID. WITH PWATS APPROACHING 2"...HEAVY RAIN AND FLASH FLOODING IS POSSIBLE. AS THE LOW INTENSIFIES OVER LAKE HURON LATE FRIDAY...A SECONDARY LOW WILL FORM OVER THE DELMARVA...TRACK ALONG THE COAST...AND MOVE INTO THE LOCAL AREA LATE FRIDAY THROUGH FRIDAY NIGHT. HEAVY RAIN AND GUSTY WINDS ALONG WITH POSSIBLE FLASH FLOODING EXPECTED. && .LONG TERM /SATURDAY THROUGH THURSDAY/... SURFACE LOW OVER SOUTHERN ONTARIO SATURDAY AM BEINGS ITS GRADUALLY FILLING PROCESS AS THE COLD FRONT FINALLY REACHES THE NYC METRO AREA. THE INSTABILITY IS RATHER LIMITED AND HAVE FOCUSED MAINLY ON THE PASSING NATURE OF SHOWERS AND CALLED IT ONLY ISOLATED FOR THE THUNDERSTORM CHANCE. MAIN FOCUS FOR HEAVIER RAINFALL WOULD BE EAST OF THE HUDSON - LONG ISLAND AND CT WITH RAINING SHOWERS. IN ADDITION...THE BEST LIKELIHOOD OF SHOWERS WOULD BE THE MORNING. IN TERMS OF MODELS...GOOD AGREEMENT IN THE DETERMINISTIC 12Z RUNS...BUT 15Z SERF IS SUPPORTING A SLOWER PASSAGE OF THE FRONT. THAT BEING SAID...HAVE INCLUDED CHC SHOWERS INTO SATURDAY NIGHT. THE FRONT CRAWLS TO JUST EAST OF MONTAUK BY SUNDAY AM. THUS...SILL CARRYING AND CHANCE OF EARLY MORNING SHOWERS FOR EASTERN LI. AGAIN SREF IS SLOWER WITH LINGERING SHOWERS INTO SUNDAY AFTERNOON. HIGH PRESSURE WILL EVENTUALLY BUILDS IN ON MONDAY. NEXT SHORTWAVE APPROACHES LATE TUESDAY WITH DIURNAL CONVECTION THAT STRETCHES INTO THE NIGHT AND CONTINUES INTO WEDNESDAY. USED 30-40 POP...BUT THERE`S GOOD AGREEMENT WITH 12Z GFS AND ECMWF HERE - SO CONFIDENCE IS FAIRLY GOOD. HIGH PRESSURE THEN FOLLOWS FOR THURSDAY INTO FRIDAY. ECMWF SHOWING A FAIRLY DEEP TROUGH FOR NEXT WEEKEND AS WELL. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... LOW PRESSURE AND ASSOCIATED FRONTAL BOUNDARY WILL MOVE SLOWLY...BUT REMAIN TO THE WEST OF THE AREA THROUGH TONIGHT. MULTIPLE CLUSTERS/LINES OF CONVECTION NEAR/IN THE FORECAST AREA LATE THIS AFTN. CURRENT TIMING IN TAFS LOOKS GOOD...SO NO MAJOR CHANGES MADE. FIRST LINE CURRENTLY MOVING THROUGH NYC TERMINALS. WATCHING ANOTHER CLUSTER NEAR KTTN...BUT IT CURRENT MOVEMENT INDICATES IT WILL REMAIN S OF NYC. ANOTHER LINE IN THE LOWER HUDSON VALLEY IS TRACKING NE AND SHOULD REMAIN N OF KHPN/KBDR UNLESS THEY BUILD ON THE SOUTHERN EDGE. MONITORING CLOSELY. BRIEF MVFR TO LOCALLY IFR CONDS MAY OCCUR AS STORMS MOVE THROUGH. FOG AND LOW CLOUDS LIKELY RETURN THIS EVENING ALONG THE COAST THEN EXPAND INLAND OVERNIGHT. LOW END MVFR CONDITIONS LIKELY...WITH IFR PSBL...ESPECIALLY COASTAL TERMINALS. SLY WINDS GENERALLY 10-15KT...WITH OCNL GUSTS AROUND 20 KT NYC TERMINALS PSBL UNTIL 00Z. SHOWERS/TS MAY MOVE IN AT TIMES EARLY TOMORROW MORNING BUT EXPECT TS TO BE ISOLD UNTIL AFTERNOON. LOW CLOUDS AND FOG SHOULD MOSTLY BURN OFF BY MID MORNING. ...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) KEWR FCSTER COMMENTS: WIND GUSTS MAY DIMINISH EARLIER THAN FORECAST. WINDS MAY SHIFT TO THE W FOR AN HOUR OR SO AFTER TS MOVE THROUGH. LOW CONFIDENCE IN TIMING OF LOW CLOUD DEVELOPMENT OVERNIGHT. KJFK FCSTER COMMENTS: WINDS MAY SHIFT TO THE W FOR AN HOUR OR SO AFTER TS MOVE THROUGH. LOW CONFIDENCE IN TIMING OF LOW CLOUD DEVELOPMENT OVERNIGHT. KLGA FCSTER COMMENTS: WIND GUSTS MAY DIMINISH EARLIER THAN FORECAST. WINDS MAY SHIFT TO THE W FOR AN HOUR OR SO AFTER TS MOVE THROUGH. LOW CONFIDENCE IN TIMING OF LOW CLOUD DEVELOPMENT OVERNIGHT. KTEB FCSTER COMMENTS: WINDS MAY SHIFT TO THE W FOR AN HOUR OR SO AFTER TS MOVE THROUGH. LOW CONFIDENCE IN TIMING OF LOW CLOUD DEVELOPMENT OVERNIGHT. KHPN FCSTER COMMENTS: WINDS MAY SHIFT TO THE W FOR AN HOUR OR SO AFTER TS MOVE THROUGH. LOW CONFIDENCE IN TIMING OF LOW CLOUD DEVELOPMENT OVERNIGHT. KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS ANTICIPATED. LOW CONFIDENCE IN TIMING OF LOW CLOUD DEVELOPMENT THIS EVENING. OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... .FRI-SAT...PERIODS OF IFR IN SCATTERED HEAVY SHOWERS AND TSTMS. LOW CLOUDS AND FOG ALSO POSSIBLE OUTSIDE OF ANY STORMS AT NIGHT. GUSTY SSE WINDS FRI AFTERNOON. .SUN-TUE...VFR. && .MARINE... GENERALLY A WEAK PRES GRADIENT WILL KEEP GRADIENT WIND GUSTS BELOW 25 KT. THUNDERSTORMS DEVELOPING THIS EVENING...THEN AGAIN FRIDAY THROUGH FRIDAY NIGHT...COULD RESULT IN THUNDERSTORM WIND GUSTS GREATER THAN 34 KT. HEAVY RAIN WILL RESULT IN DIMINISHED VSBY... RANGING FROM 1 TO 3 MILES. THE PERSISTENT SOUTHERLY FLOW WILL PUSH SEAS UP AROUND 5 FT STARTING FRIDAY NIGHT. A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS MAY BE NEEDED FRIDAY NIGHT...BUT CONFIDENCE IS NOT HIGH ENOUGH TO WARRANT ISSUING ONE AT THIS TIME...AS SEAS MAY HOVER AROUND 4 FT AND NOT QUITE MAKE IT TO 5 FT. SEAS MAY ON THE EASTERN HALF OF THE NEAR SHORE OCEAN SATURDAY...BUT BASED ON WIND FORECAST...THINK WAVEWATCH MODEL IS A BIT HIGH AND HAVE LOWERED THE FORECAST 0.5-1.0`. SEAS AND WINDS ON SUNDAY INTO EARLY NEXT WEEK ARE FORECAST BELOW SCA LEVELS. && .HYDROLOGY... A QUARTER TO A HALF INCH OF PRECIPITATION IS LIKELY THROUGH THIS EVENING ACROSS THE LOWER HUDSON VALLEY INTO PORTIONS OF NE NJ...WITH UP TO A TENTH OF AN INCH FARTHER TO THE EAST. HEAVY RAIN MOVES INTO THE REGION FRIDAY THROUGH FRIDAY NIGHT...WITH 1.25-1.5" QPF POSSIBLE OVER WESTERN ZONES AND UP TO AN INCH OVER EASTERN ZONES. LOCAL FLOODING OF LOW LYING...POOR DRAINAGE AREAS AND SMALL STREAMS IS POSSIBLE IN HEAVIER RAINFALL THIS EVENING AND AGAIN FRIDAY-FRIDAY NIGHT. HEAVIER RAIN POTENTIAL SHIFTS TO THE EAST ON SATURDAY FOR LI AND CT. AGAIN...THE PROLONGED NATURE OF THE RAINFALL SUGGESTS ONLY LOCAL PONDING/MINOR FLOOD POTENTIAL. RIVER FLOODING IS NOT EXPECTED. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$
AREA FORECAST DISCUSSION
NWS NEW YORK NY
355 PM EDT THU AUG 9 2012 .SYNOPSIS... LOW PRESSURE AND A COLD FRONT APPROACH TONIGHT THROUGH FRIDAY. A SECONDARY LOW WILL FORM AND IMPACT THE AREA FRIDAY NIGHT THROUGH SATURDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS A PRE-FRONTAL TROUGH EDGES CLOSER TO WESTERN PORTIONS OF THE CWA...SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP AND TRACK EAST. ML MUCAPE VALUES REMAIN QUITE HIGH...AVERAGING 2000-3000 J/KG OVER THE AREA...BUT MOST OF THE MODELS HAVE THE STORMS BARELY MAKING IT THROUGH NYC BEFORE ENDING JUST AS THEY APPROACH FAIRFIELD AND NASSAU COUNTIES. ONLY THE HRRR MODEL HAS STORMS GOING THROUGH NYC AND INTO WESTERN CT AND LONG ISLAND. STORMS THE DEVELOPED ALONG THE NORTH SHORE OF LONG ISLAND IN ASSOCIATION WITH THE SEA BREEZE BOUNDARY HAVE ENDED...AND DO NOT THINK MUCH ADDITIONAL ACTIVITY WILL OCCUR FROM THAT BOUNDARY. WILL FOLLOW THE GUIDANCE AND KEEP LIKELY POPS CONFINED TO FAR NW ZONES...MAINLY ORANGE/ROCKLAND AND WESTERN PASSAIC COUNTIES...AND HIGH CHANCE ALONG AND WEST OF THE HUDSON RIVER. ONCE STORMS FIRE UP AND TRACK EAST...THEY WILL MOVE INTO AN ATMOSPHERE THAT REMAINS UNSTABLE. MID-LEVEL STEERING CURRENT SEEMS LOW...SO STORMS WILL TRACK FAIRLY SLOWLY. THIS WILL RESULT IN AREAS OF LOCALLY HEAVY RAINFALL...WHICH COULD RESULT IN FLASH FLOODING. AT THE VERY LEAST...URBAN/POOR DRAINAGE/SMALL STREAM FLOODING CAN BE EXPECTED. IN ADDITION...STORMS ARE CAPABLE OF GUSTY WINDS AND FREQUENT AND DANGEROUS LIGHTNING STRIKES. STORMS TAPER OFF BY MIDNIGHT. LOW PRES OVER THE MIDWEST CONTINUES TO MOVE INTO THE OH VALLEY...SO WILL KEEP AT LEAST SLIGHT CHANCE TO LOW CHANCE POPS IN THE FORECAST THROUGH THE OVERNIGHT. WITH ABUNDANT LOW LEVEL MOISTURE IN THE ATMOSPHERE...EXPECTING LOW STRATUS/FOG TO DEVELOP AFTER MIDNIGHT. WARM AND HUMID TONIGHT WITH LOWS IN THE MID 70S IN/AROUND NYC AND IN THE UPPER 60S ELSEWHERE. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... LOW PRES OVER THE GREAT LAKES MOVES INTO THE OH VALLEY FRIDAY AFTERNOON AND INTENSIFIES AS IT THEN TRACKS OVER LAKE HURON. THIS SYSTEM WILL PUSH A WARM FRONT ALONG THE EAST COAST AND THROUGH THE REGION FROM SOUTH TO NORTH DURING THE DAY FRIDAY. AS THIS FRONT TRACKS NORTH...IT WILL HAVE UPPER LEVEL SUPPORT FROM A MID LEVEL SHORTWAVE TRACKING ALONG THE COAST. SHOWERS AND THUNDERSTORMS WILL OVERSPREAD THE REGION FROM SOUTH TO NORTH...AND WITH ELEVATED INSTABILITY OVER THE REGION...GUSTY WINDS AND FREQUENT LIGHTNING CAN BE EXPECTED. A TROPICAL AIRMASS WILL OVERSPREAD THE REGION... MAKING IT VERY WARM AND HUMID. WITH PWATS APPROACHING 2"...HEAVY RAIN AND FLASH FLOODING IS POSSIBLE. AS THE LOW INTENSIFIES OVER LAKE HURON LATE FRIDAY...A SECONDARY LOW WILL FORM OVER THE DELMARVA...TRACK ALONG THE COAST...AND MOVE INTO THE LOCAL AREA LATE FRIDAY THROUGH FRIDAY NIGHT. HEAVY RAIN AND GUSTY WINDS ALONG WITH POSSIBLE FLASH FLOODING EXPECTED. && .LONG TERM /SATURDAY THROUGH THURSDAY/... SURFACE LOW OVER SOUTHERN ONTARIO SATURDAY AM BEINGS ITS GRADUALLY FILLING PROCESS AS THE COLD FRONT FINALLY REACHES THE NYC METRO AREA. THE INSTABILITY IS RATHER LIMITED AND HAVE FOCUSED MAINLY ON THE PASSING NATURE OF SHOWERS AND CALLED IT ONLY ISOLATED FOR THE THUNDERSTORM CHANCE. MAIN FOCUS FOR HEAVIER RAINFALL WOULD BE EAST OF THE HUDSON - LONG ISLAND AND CT WITH RAINING SHOWERS. IN ADDITION...THE BEST LIKELIHOOD OF SHOWERS WOULD BE THE MORNING. IN TERMS OF MODELS...GOOD AGREEMENT IN THE DETERMINISTIC 12Z RUNS...BUT 15Z SERF IS SUPPORTING A SLOWER PASSAGE OF THE FRONT. THAT BEING SAID...HAVE INCLUDED CHC SHOWERS INTO SATURDAY NIGHT. THE FRONT CRAWLS TO JUST EAST OF MONTAUK BY SUNDAY AM. THUS...SILL CARRYING AND CHANCE OF EARLY MORNING SHOWERS FOR EASTERN LI. AGAIN SREF IS SLOWER WITH LINGERING SHOWERS INTO SUNDAY AFTERNOON. HIGH PRESSURE WILL EVENTUALLY BUILDS IN ON MONDAY. NEXT SHORTWAVE APPROACHES LATE TUESDAY WITH DIURNAL CONVECTION THAT STRETCHES INTO THE NIGHT AND CONTINUES INTO WEDNESDAY. USED 30-40 POP...BUT THERE`S GOOD AGREEMENT WITH 12Z GFS AND ECMWF HERE - SO CONFIDENCE IS FAIRLY GOOD. HIGH PRESSURE THEN FOLLOWS FOR THURSDAY INTO FRIDAY. ECMWF SHOWING A FAIRLY DEEP TROUGH FOR NEXT WEEKEND AS WELL. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... LOW PRESSURE AND ASSOCIATED FRONTAL BOUNDARY WILL MOVE SLOWLY TODAY...BUT REMAIN TO THE WEST OF THE AREA THROUGH TONIGHT. SCT TS CONTINUE TO DEVELOP ACROSS ERN PA...WITH ACTIVITY MORE ISOLATED ON LOCAL SEA BREEZES. TS TO THE WEST ARE SLOW MOVERS...AND WOULD NOT ARRIVE TO NEAR NYC UNTIL AFT 21Z. BRIEF SUB-VFR MAY OCCUR AS STORMS MOVE THROUGH--BUT THEY WILL LIKELY BE IN A WKNG STATE AND CONFIDENCE IN THIS IS LOW. FOG AND LOW CLOUDS RETURN THIS EVENING ALONG THE COAST THEN EXPAND INLAND OVERNIGHT. LOW END MVFR CONDITIONS LIKELY...WITH IFR PSBL...ESPECIALLY COASTAL TERMINALS. WINDS GENERALLY SSE 10-12KT THIS AFTERNOON...WITH OCNL G16-18KT PSBL UNTIL 22Z. SHOWERS/TS MAY MOVE IN AT TIMES EARLY TOMORROW MORNING BUT EXPECT TS TO BE ISOLD UNTIL AFTERNOON. LOW CLOUDS AND FOG SHOULD MOSTLY BURN OFF BY MID MORNING. ...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) KEWR FCSTER COMMENTS: WIND GUSTS WILL BE OCCASIONAL THIS AFTERNOON. AMENDMENTS POSSIBLE FOR TS TIMING THIS AFTERNOON. WINDS MAY SHIFT TO THE W FOR AN HOUR OR SO AFTER TS MOVE THROUGH. LOW CONFIDENCE IN TIMING OF LOW CLOUD DEVELOPMENT OVERNIGHT. KJFK FCSTER COMMENTS: WIND GUSTS WILL BE OCCASIONAL THIS AFTERNOON. AMENDMENTS POSSIBLE FOR TS TIMING THIS AFTERNOON. WINDS MAY SHIFT TO THE W FOR AN HOUR OR SO AFTER TS MOVE THROUGH. LOW CONFIDENCE IN TIMING OF LOW CLOUD DEVELOPMENT THIS EVENING. KLGA FCSTER COMMENTS: WIND GUSTS WILL BE OCCASIONAL THIS AFTERNOON. AMENDMENTS POSSIBLE FOR TS TIMING THIS AFTERNOON. WINDS MAY SHIFT TO THE W FOR AN HOUR OR SO AFTER TS MOVE THROUGH. LOW CONFIDENCE IN TIMING OF LOW CLOUD DEVELOPMENT OVERNIGHT. KTEB FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TS TIMING THIS AFTERNOON. WINDS MAY SHIFT TO THE W FOR AN HOUR OR SO AFTER TS MOVE THROUGH. LOW CONFIDENCE IN TIMING OF LOW CLOUD DEVELOPMENT OVERNIGHT. KHPN FCSTER COMMENTS: AMENDMENTS POSSIBLE FOR TS TIMING THIS AFTERNOON. WINDS MAY SHIFT TO THE W FOR AN HOUR OR SO AFTER TS MOVE THROUGH. LOW CONFIDENCE IN TIMING OF LOW CLOUD DEVELOPMENT OVERNIGHT. KISP FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS ANTICIPATED. LOW CONFIDENCE IN TIMING OF LOW CLOUD DEVELOPMENT THIS EVENING. OUTLOOK FOR 18Z FRIDAY THROUGH TUESDAY... .FRI-SAT...PERIODS OF IFR IN SCATTERED HEAVY SHOWERS AND TSTMS. LOW CLOUDS AND FOG ALSO POSSIBLE OUTSIDE OF ANY STORMS AT NIGHT. GUSTY SSE WINDS FRI AFTERNOON. .SUN-TUE...VFR. && .MARINE... GENERALLY A WEAK PRES GRADIENT WILL KEEP GRADIENT WIND GUSTS BELOW 25 KT. THUNDERSTORMS DEVELOPING THIS EVENING...THEN AGAIN FRIDAY THROUGH FRIDAY NIGHT...COULD RESULT IN THUNDERSTORM WIND GUSTS GREATER THAN 34 KT. HEAVY RAIN WILL RESULT IN DIMINISHED VSBY... RANGING FROM 1 TO 3 MILES. THE PERSISTENT SOUTHERLY FLOW WILL PUSH SEAS UP AROUND 5 FT STARTING FRIDAY NIGHT. A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS MAY BE NEEDED FRIDAY NIGHT...BUT CONFIDENCE IS NOT HIGH ENOUGH TO WARRANT ISSUING ONE AT THIS TIME...AS SEAS MAY HOVER AROUND 4 FT AND NOT QUITE MAKE IT TO 5 FT. SEAS MAY ON THE EASTERN HALF OF THE NEAR SHORE OCEAN SATURDAY...BUT BASED ON WIND FORECAST...THINK WAVEWATCH MODEL IS A BIT HIGH AND HAVE LOWERED THE FORECAST 0.5-1.0`. SEAS AND WINDS ON SUNDAY INTO EARLY NEXT WEEK ARE FORECAST BELOW SCA LEVELS. && .HYDROLOGY... A QUARTER TO A HALF INCH OF PRECIPITATION IS LIKELY THROUGH THIS EVENING ACROSS THE LOWER HUDSON VALLEY INTO PORTIONS OF NE NJ...WITH UP TO A TENTH OF AN INCH FARTHER TO THE EAST. HEAVY RAIN MOVES INTO THE REGION FRIDAY THROUGH FRIDAY NIGHT...WITH 1.25-1.5" QPF POSSIBLE OVER WESTERN ZONES AND UP TO AN INCH OVER EASTERN ZONES. LOCAL FLOODING OF LOW LYING...POOR DRAINAGE AREAS AND SMALL STREAMS IS POSSIBLE IN HEAVIER RAINFALL THIS EVENING AND AGAIN FRIDAY-FRIDAY NIGHT. HEAVIER RAIN POTENTIAL SHIFTS TO THE EAST ON SATURDAY FOR LI AND CT. AGAIN...THE PROLONGED NATURE OF THE RAINFALL SUGGESTS ONLY LOCAL PONDING/MINOR FLOOD POTENTIAL. RIVER FLOODING IS NOT EXPECTED. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...MPS NEAR TERM...MPS SHORT TERM...MPS LONG TERM...JST AVIATION...PW MARINE...MPS/JST HYDROLOGY...MPS/JST
AREA FORECAST DISCUSSION
NWS ALBANY NY
1020 AM EDT THU AUG 9 2012 .SYNOPSIS... A FRONTAL BOUNDARY WILL SLOWLY TRACK SOUTHWARD AND STALL OVER UPSTATE NEW YORK TODAY...ALLOWING FOR SHOWERS AND THUNDERSTORMS DURING THE AFTERNOON AND EVENING HOURS. A FEW OF THESE STORMS MAY BE STRONG. MEANWHILE...LOW PRESSURE WILL ORGANIZE OVER THE MIDWEST TONIGHT...AND MOVE INTO THE EASTERN GREAT LAKES BY SATURDAY. ITS ASSOCIATED COLD FRONT WILL ADVANCE TOWARD THE LOCAL REGION FRIDAY AND CROSS THE REGION SATURDAY...ALLOWING FOR ADDITIONAL SHOWERS AND THUNDERSTORMS...SOME OF WHICH WILL CONTAIN HEAVY RAINFALL. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1020 AM EDT...THE POTENTIAL IS INCREASING FOR A FEW SEVERE THUNDERSTORMS THIS AFTERNOON AND INTO THE EVENING HOURS. FOG/STRATUS HAS CLEARED OUT OF THE MAJORITY OF THE AREA...AND DEWPOINTS REMAIN VERY HIGH...WITH TDS CURRENTLY 65-70 DEGREES F. A STALLED OUT STATIONARY BOUNDARY REMAINS JUST NORTHWEST OF THE REGION. ALTHOUGH DEEP LAYER SHEAR IS LIMITED FOR SOUTHEASTERN AREAS...IT SHOULD INCREASE TO 25-40 KTS FOR AREAS NORTH AND WEST OF THE CAPITAL REGION BY LATE THIS AFTN/THIS EVENING /ACCORDING TO THE 06Z GFS/. FORECASTED CAPE FOR TODAY OFF THE 12Z KALY SOUNDING IS ABOUT 2300-2800 J/KG ACROSS THE REGION...AND MID LEVEL LAPSE RATES ARE RESPECTABLE /BOTH THE 06Z GFS AND NAM SHOW 850-500 MB LAPSE RATES OF AROUND 6 C/KM/. AS A RESULT...SPC HAS NUDGED MOST OF OUR AREA BACK IN THE SLIGHT RISK. WE WILL NEED TO MONITOR RADAR TRENDS BY THE EARLY AFTN HOURS...AS BOTH THE LOCAL HIRES WRF AND 3KM HRRR SHOW CONVECTION DEVELOPING DURING THE EARLY AFTN HOURS...ALTHOUGH THE HRRR SHOWS THE ACTIVITY BECOMING MORE ORGANIZED THAN THE WRF. TONIGHT...THE FORECAST WRF NMM AND ARW CORES SUGGEST A LULL IN THE ACTIVITY AS THE MAIN UPPER LOW CURRENTLY TRACKING ACROSS THE ARROWHEAD OF MINNESOTA BEGINS TO CARVE OUT AN ANOMALOUS LOWERING HEIGHTS INTO THE OHIO VALLEY AND CENTRAL GREAT LAKES REGION. HOWEVER...THE GLOBAL MODELS SUGGEST THE INCREASE IN THETA-E/MOISTURE TRANSPORT VECTOR MAGNITUDES WILL CONTINUE WITH SHOWER DEVELOPMENT OVERNIGHT. MOS GUIDANCE DOES LOWER POPS OVERNIGHT BUT NOT TOO LOW TO DROP MENTION OF PRECIP FROM THE FORECAST/GRIDS. THEREFORE...WE WILL CONTINUE WITH THE 30-40% POPS OVERNIGHT FOR THE ENTIRE REGION WITH SHOWERS AND THE CHANCE FOR THUNDERSTORMS. AS LOW LEVEL MOISTURE INCREASES FURTHER AND SURFACE WINDS EXPECTED TO DECOUPLE...AREAS OF FOG ARE EXPECTED AND WILL INCLUDE IN THE GRIDS/FORECAST. OVERNIGHT LOWS WILL BE WARM AND MUGGY WITH VALUES MAINLY INTO THE L-U 60S. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... AN ACTIVE PERIOD OF WEATHER WITH THE POTENTIAL FOR SEVERE WEATHER AND HEAVY RAINFALL... NCEP MODEL SUITE AND INTERNATIONAL GUIDANCE THIS MORNING CONTINUE TO ADVERTISE AN UNSEASONABLY LOWER HEIGHT ANOMALIES OVER THE MID WEST AS UPPER LOW EVOLVES. THIS LEAVES OUR REGION WITHIN A SOUTHERLY INCREASE OF WARM AND MOIST CONVEYOR BELT AS PWATS CLIMB TOWARD 2 INCHES THROUGH THE SHORT TERM. SEVERE POTENTIAL ON FRIDAY COULD BE RATHER INTERESTING AS IT WILL BE HIGHLY DEPENDENT ON ACCUMULATED INSOLATION. AS THIS UPSTREAM SYSTEM DEEPENS...OUR LOW LEVEL FLOW IS FORECAST TO BACK SLIGHTLY WHICH COULD BE MESOSCALE ENHANCED WITHIN THE HUDSON VALLEY REGION. MUCAPES ON FRIDAY COULD EXCEED 2K J/KG WITH ENOUGH INSOLATION FOR MORE ROBUST CONVECTION. IN COLLABORATION WITH SPC THIS MORNING...SLIGHT RISK WAS ADJUSTED NORTHWARD TO ENCOMPASS THE SOUTHERN 2/3RDS OF THE CWFA. PER THERE EXCELLENT DISC... SOMEWHAT STRONGER DEEP AND LOW LEVEL SHEAR MAY DEVELOP FROM NRN MID ATLANTIC INTO ERN PORTION OF THE OH VALLEY AND NERN STATES IN ASSOCIATION WITH A MID LEVEL JET ROTATING THROUGH SERN PERIPHERY OF THE UPPER LOW. IF SUFFICIENT INSTABILITY DEVELOPS...STORMS MAY BECOME A BIT MORE ORGANIZED IN THIS REGION WITH POTENTIAL FOR EMBEDDED MESOCYCLONES AND BOWING SEGMENTS. DAMAGING WIND WILL BE THE MAIN THREAT...BUT A CONDITIONAL THREAT WILL EXIST FOR A COUPLE OF TORNADOES. FURTHERMORE...AS THOSE PWATS INCREASE...SO DOES THE POTENTIAL FOR HEAVY RAINFALL FRIDAY INTO FRIDAY NIGHT. PER THE CSTAR III RESEARCH...SEVERAL PIECES POINT TOWARD HEAVY RAINFALL BUT NOT ALL OF THE PIECES APPEAR TO LINE UP TOO WELL. WHILE THE POTENTIAL FOR SOME TRAINING ECHOES IS APPARENT...FLASH FLOOD GUIDANCE REMAINS RATHER HIGH WITH COUNTY VALUES RANGING FROM 2-4 INCHES ALONG WITH OUR RECENT DRY WEATHER TRENDS. SO HEADLINES AT THE PRESENT TIME AS WE WILL CLOSELY MONITOR TRENDS AND CONTINUE TO MAKE FORECAST ADJUSTMENTS. WE WILL CONTINUE TO HIGHLIGHT THESE HAZARDS IN THE HWO THIS MORNING. GUIDANCE IS SOMEWHAT IN TIMING DISAGREEMENTS WITH THE DEPARTURE OF THE FRONTAL BOUNDARY ON SATURDAY. AS SUGGESTED BY THE LATEST ENSEMBLES...WE WILL FAVOR MORE TOWARD THE ECMWF TIMING WHICH KEEPS POPS INTO THE CHC-SCT CATEGORY ALONG AND EAST OF THE HUDSON RIVER WITH DECREASED POPS FURTHER WEST AS THAT DRY SLOT APPROACHES. AS SOME PARTIAL SUNSHINE IS EXPECTED...ALONG WITH A MOIST GROUND...HIGHS SATURDAY AFTERNOON CLIMB INTO THE LOWER 80S FOR VALLEY LOCATIONS AND 70S ELSEWHERE PER 850MB TEMPS INTO THE LOWER-MID TEENS CELSIUS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... HAVE POPULATED THIS PORTION OF GRIDDED DATABASE WITH A 50/50 BLEND OF 18Z/08 HPC GUIDANCE AND 00Z/09 GMOS. SAT NT-SUN NT...MAIN OCCLUDED/COLD FRONT SHOULD MOVE E OF THE REGION EARLY SAT NT...AS MID LEVEL DRY SLOT PUNCHES NORTHEAST ACROSS AREA. THIS SHOULD ALLOW SHOWERS TO TAPER OFF...ALTHOUGH CAN NOT COMPLETELY RULE OUT ADDITIONAL LIGHTER SHOWERS...OR AREAS OF DRIZZLE...ESP ACROSS THE SOUTHERN ADIRONDACKS...AND HIGHER ELEVATIONS ACROSS WESTERN NEW ENGLAND. THEN...AS THE MID/UPPER LEVEL COLD POOL MOVE ACROSS DURING SUNDAY/SUNDAY EVENING...DIURNALLY DRIVEN SHOWERS SHOULD DEVELOP...ESP ACROSS HIGHER ELEVATIONS. WILL INDICATE SLIGHT CHC TO LOW CHC POPS FOR SUNDAY TO ACCOUNT FOR THIS. EXPECT TEMPS TO BE NEAR OR A BIT BELOW SEASONAL LEVELS...GENERALLY 75-80 WITHIN VALLEY REGIONS...AND 60S TO LOWER 70S ACROSS HIGHER ELEVATIONS. OVERNIGHT MINS SHOULD FALL INTO HE LOWER 60S IN VALLEY AREAS...AND 50S ELSEWHERE FOR SUNDAY MORNING...THEN A FEW DEGREES COOLER...MAINLY 50S...FOR MON AM. MONDAY-MONDAY NIGHT...WEAK RIDGE OF HIGH PRESSURE SHOULD SLIDE ACROSS THE REGION...WITH GENERALLY FAIR CONDITIONS. TEMPS SHOULD REACH 80-85 IN VALLEYS..AND 75-80 ACROSS HIGHER ELEVATIONS...WITH OVERNIGHT MINS FALLING INTO THE LOWER 60S ACROSS THE HUDSON RIVER VALLEY...AND LOWER/MID 50S ACROSS THE SOUTHERN ADIRONDACKS. TUE-WED...MOST LONG RANGE MODELS INDICATE ANOTHER POTENTIAL UPPER LEVEL LOW DIGGING SOUTHWARD FROM EASTERN CANADA INTO THE NORTHEAST STATES. DEPENDING ON THE EXPECT PATH AND EVOLUTION OF THIS FEATURE...SHOWERS AND POSSIBLE THUNDERSTORMS MAY OCCUR DURING THIS PERIOD...ESP TUE NT/WED. TEMPS SHOULD REACH 80-85 IN VALLEYS...AND 75-80 ACROSS HIGHER ELEVATIONS...WITH OVERNIGHT MINS FALLING INTO THE LOWER/MID 60S IN VALLEYS...AND 55-60 ACROSS HIGHER ELEVATIONS. 500HPA CUTOFF LIFTS NNE INTO QB TAKING CLOUDS AND THE THREAT OF -SHRA WITH IT SUNDAY ON ECMWF. AT SFC W FLOW BCMS EST ACROSS THE RGN..AND BY EVENING SFC HIGH BUILDS OVER THE MID ATLC. GFS/GEM HOLDING SOME CLOUDS AND MINIMAL QPF OVER NW PERIPHERY OF FCA...BUT OTRW A FAIR DAY. CONDS REMAIN DRY MONDAY AS SFC HIGH HOLDS OVER MID ATLC AND 500HPA REMAINS ZONAL. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... A WEAK COLD FRONT WILL GRADUALLY APPROACH FROM THE NORTH AND WEST TODAY...TRIGGERING SCATTERED AFTERNOON/EVENING SHOWERS AND THUNDERSTORMS. AREAS OF MVFR/IFR CIGS AND VSBYS WILL PERSIST INTERMITTENTLY AT THE TAF SITES THROUGH AROUND 14Z/THU...BEFORE GRADUALLY DISSIPATING. THEN...SCATTERED SHOWERS/TSTMS WILL DEVELOP THIS AFTERNOON...MAINLY AFTER 18Z. THE THREAT FOR SHOWERS AND THUNDERSTORMS WILL GRADUALLY DECREASE AFTER 02Z/FRI. AREAS OF MVFR/IFR CIGS AND VSBYS WILL LIKELY DEVELOP ONCE AGAIN AFTER 06Z/FRI. WINDS WILL BECOME SOUTH TO SOUTHWEST AT 5-10 KT THIS AFTERNOON...THEN WILL BECOME LIGHT/VARIABLE ONCE AGAIN TONIGHT. WINDS WILL BE MUCH STRONGER...AND VARIABLE IN DIRECTION IN AND NEAR ANY THUNDERSTORMS. OUTLOOK... FRI-SAT...MVFR/IFR. SHRA/TSRA LIKELY. AM LOW CLOUDS/FOG. SAT NGT-MON...VFR. NO SIG WX. && .FIRE WEATHER... MINIMAL FIRE WEATHER CONCERNS AS INCREASING LOW LEVEL MOISTURE ALONG WITH POTENTIAL FOR SHOWERS AND THUNDERSTORMS...ALONG WITH HEAVY RAINFALL...WILL KEEP RELATIVE HUMIDITIES AT OR ABOVE 50 PERCENT THROUGH THE END OF THE WEEK. && .HYDROLOGY... A MODERATE TO SIGNIFICANT HEAVY RAINFALL EVENT REMAINS POSSIBLE THROUGH FRIDAY NIGHT WITH A GENERAL 1-3 INCHES PER THE LATEST QPF GUIDANCE WITH LOCALIZED AMOUNTS OF 3-4 INCHES POSSIBLE. SCATTERED SHOWERS/THUNDERSTORMS ARE EXPECTED TO DEVELOP THURSDAY...WITH NUMEROUS SHOWERS AND STORMS EXPECT FRIDAY INTO FRIDAY NIGHT AS A SERIES OF FRONTAL PASSAGES AND ANOMALOUS UPPER LOW OVER THE MID WEST IMPACTS THE AREA. IT IS STILL TOO EARLY TO DETERMINE WHERE THE HIGHEST PRECIPITATION AMOUNTS WOULD BE....HOWEVER THERE REMAINS A CONCERN FOR POSSIBLE FLASH FLOODING. AS FAR AS MAIN STEM RIVERS GO...THERE COULD BE SIGNIFICANT WITHIN BANK RISES ON SOME DEPENDING ON WHERE THE AXIS OF HEAVY RAINFALL SETS UP. HOWEVER...GIVEN THE DRY CONDITIONS OF LATE...AT THIS POINT...WIDESPREAD RIVER FLOODING APPEARS UNLIKELY. DUE TO ALL THESE FACTORS MENTIONED ABOVE...WILL KEEP MENTION FOR THE POSSIBILITY FOR HEAVY RAINFALL IN OUR HAZARDOUS WEATHER OUTLOOK. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...FRUGIS/BGM NEAR TERM...FRUGIS/BGM SHORT TERM...BGM LONG TERM...KL AVIATION...KL FIRE WEATHER...BGM HYDROLOGY...BGM
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1142 AM EDT THU AUG 9 2012 .SYNOPSIS... A WEAK COLD FRONT WILL SLOWLY MOVE TOWARD OUR AREA TODAY AND TONIGHT. AN AREA OF LOW PRESSURE HOWEVER WILL THEN MOVE ACROSS THE GREAT LAKES REGION AND INTO SOUTHEASTERN CANADA FRIDAY AND SATURDAY. AN ASSOCIATED COLD FRONT WILL SLIDE ACROSS OUR REGION SATURDAY, FOLLOWED BY WEAK HIGH PRESSURE SUNDAY THROUGH TUESDAY. THE NEXT COLD FRONT IS FORECAST TO APPROACH FROM THE NORTHWEST WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A WEAK MID LEVEL IMPULSE, SOME H8 THETA E ADVECTION AND INSTABILITY WITH DIMINISHING CIN WERE ENOUGH TO TRIGGER ISOLATED CONVECTION FROM W OF MPO TO NEAR IAD LATE THIS MORNING. THE THETA E ADVECTION SEEMS PROGGED MAINLY FOR OUR NORTHERN AND WESTERN ZONES THIS AFTERNOON. THE IMPULSE SHOULD CLEAR US TO OUR SOUTHEAST BY EARLY AFTERNOON AND PUT US INTO A REGION OF NVA, SO WE AREN`T REALLY ENTHUSIASTIC ABOUT INGREDIENTS COMING TOGETHER TO CAUSE THE KIND OF BLOSSOMING OF CONVECTION THAT THE 12Z RUN OF THE HRRR WAS SHOWING. ON THE OTHER HAND, THE THETA E ADVECTION AND INSTABILITY ARE REAL AND SOME MODERATE BULK SHEAR WILL BE ON OUR NORTHWESTERN DOORSTEP BY 00Z. WE ARE STANDING PAT WITH THE CHANCE TO SLIGHT CHANCE AFTERNOON POPS PUSHING FROM NORTHWEST TO AROUND THE I-95 CORRIDOR AT THIS TIME. REGARDING TEMPERATURES, THE MORNING SOUNDINGS FROM IAD, APG AND OKX SUPPORTED THE MAX TEMPERATURE FORECAST. COOLER TEMPERATURES ALONG THE COAST THANKS TO THE SOUTH-SOUTHEAST SURFACE FLOW WERE VERIFYING. THE ONLY CHANGE WE MADE WAS TO THE SOUTHERN POCONOS WHERE THE TEMPERATURES WERE SIMILAR TO THOSE IN FAR NORTHWEST NJ. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... LINGERING CONVECTION IS FORECAST TO DRIFT EASTWARD THIS EVENING. WE WILL MENTION A CHANCE OF SHOWERS AND THUNDERSTORMS FOR MUCH OF OUR REGION, KEEPING ONLY A SLIGHT CHANCE NEAR THE COAST. SCATTERED TO ISOLATED CONVECTION MAY PERSIST INTO THE LATE NIGHT HOURS AS A MID LEVEL IMPULSE IN THE SOUTHWESTERLY FLOW LIFTS OVER OUR REGION. ALSO, A SURFACE BOUNDARY FROM THE SOUTHWEST AND SOUTH IS EXPECTED TO ARRIVE. WITH HIGH HUMIDITY LEVELS, TEMPERATURES SHOULD DROP ONLY INTO THE 7OS TONIGHT, EXCEPT IN THE ELEVATED TERRAIN WHERE SOME READINGS IN THE UPPER 60S ARE POSSIBLE. THE FRONTAL BOUNDARY AND LOW LEVEL MOISTURE FROM ANY CONVECTION MAY CAUSE THE DEVELOPMENT OF SOME FOG AND LOW CLOUDS LATE TONIGHT. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... THIS TIME FRAME LOOKS TO START ON THE ACTIVE SIDE /POTENTIALLY LOCALLY HEAVY RAIN AND STRONG CONVECTION/ ALONG WITH HUMID CONDITIONS, FOLLOWED BY A MORE CALMER TIME. THE OVERALL SYNOPTIC SETUP IS COMPRISED OF A VIGOROUS SHORT WAVE AMPLIFYING INTO A CLOSED LOW ACROSS THE GREAT LAKES AND SOUTHEASTERN CANADA. THIS FEATURE THEN SHIFTS NORTHEASTWARD LATER FRIDAY AND SATURDAY. THIS SYSTEM THOUGH MAY BE SLOW TO MOVE NORTHEASTWARD ESPECIALLY DEPENDING ON HOW CLOSED OFF IT BECOMES. THERE DOES HOWEVER LOOK LIKE ENOUGH OF A FLOW AND ENERGY UPSTREAM TO PUSH THE CLOSED LOW NORTHEASTWARD AS WE GO THROUGH SATURDAY AND SUNDAY. THE PATTERN THEN LOOKS TO TRANSITION TO MORE ZONAL /SOME TROUGHING HOLDING ON THOUGH FROM THE GREAT LAKES INTO THE NORTHEAST/ WITH WEAK HIGH PRESSURE BUILDING FROM THE UPPER OHIO VALLEY TO THE MID ATLANTIC. THE NEXT COLD FRONT MAY THEN BE APPROACHING FROM THE NORTHWEST WEDNESDAY. FOR FRIDAY, AS THE UPPER-LEVEL TROUGH AMPLIFIES TO OUR NORTHWEST AND CLOSES OFF, A DEEP SOUTHERLY FLOW WILL ALLOW MOISTURE TO INCREASE /PW VALUES NEAR 2 INCHES/. THIS IN COMBINATION WITH A SOMEWHAT STRONGER WIND FIELD AND LOWERING HEIGHTS ARRIVING WILL RESULT IN AN INCREASE IN SHOWERS AND THUNDERSTORMS. THE SEVERE THREAT WILL GENERALLY BE DETERMINED BY HOW MUCH HEATING OCCURS, AS THE SHEAR IS FORECAST TO INCREASE TO ABOUT 20-30 KNOTS FRIDAY INTO EARLY SATURDAY. IT APPEARS THAT AT LEAST A FEW SHOWERS AND THUNDERSTORMS COULD BE ONGOING TO START FRIDAY ALTHOUGH THE OVERALL COVERAGE SHOULD BE LIMITED AND MOSTLY ACROSS OUR WESTERN ZONES. HOWEVER, POCKETS OF STRONGER HEATING MAY ALLOW FOR MORE ROBUST CONVECTION TO DEVELOP. THERE IS SOME TIMING DIFFERENCES WITH SOME GUIDANCE A BIT FASTER WITH THE ASSOCIATED SURFACE LOW AND COLD FRONT. FRIDAY LOOKS TO BE ACTIVE WITH SHOWERS AND THUNDERSTORMS OCCURRING AT ANY TIME ALTHOUGH THE AFTERNOON AND AT NIGHT LOOKS TO BE MORE FAVORED AS THE MAIN THRUST OF THE INCOMING SHARPENING TROUGH ARRIVES. THE GUIDANCE INDICATES THAT THE MLCAPE VALUES INCREASE UP TO 1500 J/KG FRIDAY GIVEN A WARM AND RATHER MOIST AIR MASS. THIS MAY BECOME PROBLEMATIC THOUGH REGARDING THE SEVERE WEATHER POTENTIAL AS SHOWERS AND STORMS MAY TEND TO DEVELOP QUICKLY. IN ADDITION, THERE IS THE POTENTIAL FOR A FAIR AMOUNT OF CLOUDS TO BE AROUND AND LIMITING THE OVERALL INSTABILITY. ANY MORE ROBUST STORMS THAT CAN SUSTAIN THEMSELVES AND EVEN BECOME ORGANIZED WILL INCREASE THE LOCALLY STRONG WIND THREAT /DOWNBURST POTENTIAL DUE TO WATER LOADED DOWNDRAFTS APPEARS TO BE THE MAIN THREAT/, ALTHOUGH SOME HAIL IS POSSIBLE IF CONVECTIVE ELEMENTS CAN BECOME TALL ENOUGH. THE DEEP AND LOW-LEVEL SHEAR MAY BECOME SOMEWHAT STRONGER IN ASSOCIATION WITH A MID LEVEL JET ROTATING THROUGH THE SOUTHEASTERN PERIPHERY OF THE UPPER LOW. IF SUFFICIENT INSTABILITY DEVELOPS, STORMS MAY BECOME A BIT MORE ORGANIZED WITH THE POTENTIAL FOR BOWING SEGMENTS. IN ADDITION, THE POTENTIAL EXISTS FOR THE LOW-LEVEL WINDS TO BACK MORE TO THE SOUTHEAST WHILE ALOFT THEY ARE FROM THE SOUTHWEST, ADDING TO THE LOW-LEVEL SHEAR. AGAIN IF ENOUGH INSTABILITY CAN DEVELOP AND BE MAINTAINED, SOME CONVECTIVE ELEMENTS MAY BE ABLE TO DEVELOP SOME STORM ROTATION. THERE WILL ALSO BE THE POTENTIAL FOR LOCALLY VERY HEAVY RAIN AS RAINFALL RATES SHOULD BE EFFICIENT. THE STEERING FLOW LOOKS TO BE ABOUT 20 KNOTS THEREFORE THE SHOWERS AND STORMS WILL BE MOVING, BUT WE MAY HAVE TO WATCH FOR TRAINING CELLS. FOR NOW, WE WILL CONTINUE TO INCLUDE A POSSIBLE HEAVY RAIN MENTION IN THE FORECAST BUT OPTED TO NOT INCLUDE OTHER ENHANCED WORDING ATTM DUE TO LOWER CONFIDENCE REGARDING COVERAGE/INSTABILITY AND OVERALL STORM EVOLUTION. A MENTION HOWEVER FOR THE POTENTIAL OF SOME SEVERE STORMS WILL BE CONTINUED IN THE HAZARDOUS WEATHER OUTLOOK. FOR SATURDAY, THE CLOSED LOW ALLOWS THE SURFACE LOW TO BE CAPTURED NEAR THE EASTERN GREAT LAKES REGION WITH THE ASSOCIATED COLD OR OCCLUDED FRONT SHIFTING OFF THE COAST WITH TIME. THIS WILL BRING AN END TO THE SHOWERS AND THUNDERSTORMS DURING THE COURSE OF THE DAY WITH THE MORNING BEING THE MOST ACTIVE AS OF NOW. A DRY SLOT SHOULD BE WORKING INTO THE AREA DURING THE AFTERNOON AS THE CLOSED LOW SLOWLY LIFTS NORTHEASTWARD. DESPITE THE CYCLONIC FLOW PERSISTING THROUGH THE NIGHT, THE LACK OF APPRECIABLE LIFT SHOULD KEEP ANY SHOWER THREAT RATHER LOW. IT SHOULD BE TURNING LESS HUMID DURING THE COURSE OF THE AFTERNOON AS DRYING PUSHES IN FROM THE WEST. FOR SUNDAY AND MONDAY, THE AFOREMENTIONED CLOSED LOW GRADUALLY LIFTS AWAY FROM OUR AREA WITH A TROUGH AXIS SLIDING ACROSS. THIS KEEPS OUR AREA AT LEAST FOR SUNDAY WITHIN A CYCLONIC FLOW ALOFT WHILE HIGH PRESSURE AT THE SURFACE BUILDS IN. THE MAIN COLD POOL ALOFT LOOKS TO DRIFT FAR ENOUGH NORTH TO KEEP ANY SHOWERS REMOVED FROM OUR REGION, ALTHOUGH THERE COULD BE ADDITIONAL CUMULUS DEVELOPMENT DURING PEAK HEATING. AS AT LEAST SOME MIXING OCCURS ALONG WITH AN AIR MASS CHANGE, DEW POINTS SHOULD BE LOWER TO PROVIDE A MORE PLEASANT DAY. DESPITE THE MID LEVEL FLOW TURNING MORE ZONAL LATE SUNDAY AND MONDAY, SOME GUIDANCE HINTS AT A SHORT WAVE TRACKING SOUTHEASTWARD FROM THE MIDWEST. SOME CONVECTION MAY BE TIED TO THIS AS SOME WAA AND MOISTURE ADVECTION OCCURS AHEAD OF IT. FOR NOW, OPTED TO KEEP MONDAY DAY DRY AND CONTINUE SLIGHT CHC POPS AT NIGHT. FOR TUESDAY AND WEDNESDAY, WHILE THE FLOW TRIES TO MAINTAIN A MORE ZONAL ORIENTATION IT APPEARS THAT THERE WILL BE SOME SHORT WAVES EMBEDDED WITHIN THIS FLOW. THIS MAY TEAM UP OR ENHANCE SOME WAA AHEAD OF IT WITH POSSIBLE ISOLATED TO SCATTERED CONVECTION AS A RESULT. SOME OF THE GUIDANCE TENDS TO AMPLIFY AT LEAST ONE SHORT WAVE SOME DURING THIS TIME FRAME WHICH RESULTS IN A HIGHER CONVECTIVE POTENTIAL. AS OF NOW, WE DID NOT MAKE MUCH IN THE WAY OF CHANGES AS TIMING OF THESE FEATURES IS MORE DIFFICULT THIS FAR OUT. IF THERE IS LITTLE IN THE WAY OF TROUGH AMPLIFICATION AND THE SHORT WAVE REMAINS WEAKER, THEN WE MAY HAVE TO WAIT FOR A COLD FRONT TO APPROACH DURING WEDNESDAY FOR PERHAPS A BETTER CHC OF CONVECTION. LITTLE CHANGES WERE MADE TO THE TEMPERATURES ATTM. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. INTO THE AFTERNOON HOURS, MAINLY VFR CONDITIONS ARE ANTICIPATED WITH SOME SCATTERED CUMULUS DEVELOPING. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO FORM OVER THE TERRAIN OF NORTHEASTERN PENNSYLVANIA EARLY THIS AFTERNOON AND THEY MAY EXPAND TO THE SOUTH AND EAST. AS A RESULT, THERE IS THE POTENTIAL FOR A MID TO LATE AFTERNOON SHOWER OR THUNDERSTORM AT KRDG AND KABE. HOWEVER, THERE IS NOT ENOUGH FORECAST CONFIDENCE REGARDING THE TIMING AND ACTUAL IMPACT AT THOSE TWO LOCATIONS TO INCLUDE THE MENTION IN THE TAFS AT THIS POINT. A SOUTHERLY FLOW AT 5 TO 10 KNOTS IS EXPECTED. SCATTERED TO ISOLATED SHOWERS AND THUNDERSTORMS ARE FORECAST TO LINGER IN OUR REGION INTO TONIGHT. AGAIN, THE FORECAST CONFIDENCE LEVEL IS NOT HIGH ENOUGH TO INCLUDE THEIR MENTION IN THE TAFS AT THIS TIME. WITH THE LOW LEVEL MOISTURE AND A SURFACE BOUNDARY LIFTING NORTHWARD INTO OUR REGION LATE TONIGHT, SOME FOG AND LOW CLOUDS ARE POSSIBLE. OUTLOOK... FRIDAY AND SATURDAY...SHOWERS AND THUNDERSTORMS WILL INCREASE THROUGH THE DAY FRIDAY AND CONTINUE SATURDAY MORNING AS A COLD FRONT APPROACHES AND THEN MOVES THROUGH THE REGION. VFR WILL BECOME MVFR OR EVEN LOWER ESPECIALLY IF SHOWERS AND STORMS BECOME RATHER WIDESPREAD. THE AIR MASS WILL BE RATHER HUMID AS WELL, THEREFORE CEILINGS MAY REMAIN LOW ESPECIALLY FRIDAY NIGHT AND EARLY SATURDAY MORNING. THE OVERALL CONDITIONS ARE EXPECTED TO IMPROVE TO VFR DURING THE SATURDAY FROM WEST TO EAST. SUNDAY AND MONDAY...VFR. && .MARINE... THE SOUTHERLY FLOW IS EXPECTED TO INCREASE INTO THE 10 TO 15 KNOT RANGE FOR TODAY AND TONIGHT. WAVE HEIGHTS ON OUR OCEAN WATERS SHOULD REMAIN IN THE 2 TO 3 FOOT RANGE. ON DELAWARE BAY, WAVE HEIGHTS WILL LIKELY BE 2 FEET OR LESS. OUTLOOK... A VIGOROUS SYSTEM CLOSING OFF ACROSS THE GREAT LAKES AND UPPER OHIO VALLEY WILL DRIVE A SURFACE LOW ACROSS THE EASTERN GREAT LAKES FRIDAY INTO SATURDAY. AN ASSOCIATED COLD/OCCLUDED FRONT WILL MOVE THROUGH OUR AREA SATURDAY. AHEAD OF THIS FEATURE, A SOUTHERLY FLOW WILL OCCUR AND STRENGTHEN SOME AS THE PRESSURE GRADIENT TIGHTENS. AN EXAMINATION OF THE 925 MB FORECAST WINDS REVEALS 25-30 KNOTS MOVES THROUGH FRIDAY NIGHT AND SATURDAY MAINLY AHEAD OF AND ALONG THE COLD FRONT. THIS MAY RESULT IN A PERIOD OF ADVISORY LEVEL GUSTS, AND THE SOUTHERLY FLOW WILL TEND TO BUILD THE SEAS TO NEAR 5 FEET ON THE OCEAN. AS A RESULT, A SMALL CRAFT ADVISORY MAY BE NEEDED FOR FRIDAY AND AT LEAST PART OF SATURDAY BUT FOR NOW HELD OFF. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO BECOME MORE NUMEROUS DURING FRIDAY AND SATURDAY MORNING BEFORE ENDING. SOME STORMS COULD BE CAPABLE OF PRODUCING LOCALLY GUSTY WINDS. A WEAK AREA OF HIGH PRESSURE THEN BEGINS TO BUILD INTO OUR REGION SUNDAY AND MONDAY WITH A LIGHT WESTERLY WIND THAT MAY TURN SOUTHERLY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...NONE. && $$ SYNOPSIS...GORSE NEAR TERM...IOVINO/DELISI SHORT TERM...IOVINO LONG TERM...GORSE AVIATION...GORSE/IOVINO MARINE...GORSE/IOVINO
AREA FORECAST DISCUSSION
NWS MIAMI FL
250 PM EDT THU AUG 9 2012 .AVIATION... OUTSIDE OF A BRIEF SHOWER SPREADING ASHORE ALONG THE EAST COAST...VFR CONDITIONS SHOULD PERSIST THROUGH REMAINDER OF THE DAY TODAY. HOWEVER...FOR APF...WILL KEEP VCTS IN THIS TAF PACKAGE FOR THE LATE AFTERNOON AND EVENING PERIODS WHERE THE BEST CHANCE FOR SCATTERED SHOWERS AND STORMS WILL BE. OVERNIGHT...DEEP LAYER MOISTURE IS FORECAST TO SPREAD OVER THE AREA FROM THE SOUTHEAST...WHICH WILL BRING THE RAINFALL CHANCES BACK TO THE AREA...ESPECIALLY ACROSS THE EAST COAST TERMINALS LATE TONIGHT THROUGH THE FIRST PORTION OF THE DAY FRIDAY. THEREFORE...WILL INCLUDE VCSH FOR ALL EAST COAST SITES LATE TONIGHT...THEN VCTS FOR APF LATER IN THE PERIOD. WINDS WILL REMAIN MOSTLY LIGHT OUT OF THE SOUTHEAST...THEN VEER TO THE SOUTH OVER THE WEEKEND. 85/AG && .PREV DISCUSSION... /ISSUED 1043 AM EDT THU AUG 9 2012/ UPDATE...THE LATEST HRRR SHOWS QUITE A BIT OF CONVECTION DEVELOPING OVER THE INTERIOR AND ESPECIALLY THE GULF COAST/NAPLES AREA THIS AFTERNOON. THE MIAMI SOUNDING THIS MORNING SHOWS SUFFICIENT MOISTURE FOR CONVECTION...WITH A PWAT OF 1.62 INCHES AND THE DRIEST AIR IN THE MID LEVELS. HAVE INCREASED THE COVERAGE OF SHOWERS/TSTORMS FOR THE INTERIOR AND GULF COAST...WITH THE HIGHEST POPS ACROSS THE NAPLES AREA. WEAK LAPSE RATES ARE PRESENT BUT GIVEN STRONG HEATING AND MID LEVEL DRY AIR...A FEW STRONG STORMS ARE POSSIBLE WHERE CONVERGENCE IS MAXIMIZED WHICH LOOKS TO BE ACROSS THE GREATER NAPLES AREA LATE THIS AFTERNOON. STRONG WIND GUSTS TO AROUND 50 MPH WOULD BE THE MAIN CONCERN IN THE STRONGEST STORMS...AS WELL AS FREQUENT LIGHTNING. /GREGORIA PREV DISCUSSION... /ISSUED 655 AM EDT THU AUG 9 2012/ AVIATION... EASTERLY FLOW EXPECTED TO CONTINUE THROUGH THE PERIOD AT ALL EAST COAST SITES WITH VFR CONDITIONS. KEPT VCTS MENTION AT KAPF AS A WEAK GULF COAST SEA BREEZE COULD DEVELOP DURING THE EARLY AFTERNOON HOURS RESULTING IN SCATTERED SHRA/TSTMS. PREV DISCUSSION... /ISSUED 326 AM EDT THU AUG 9 2012/ SHORT TERM...TODAY THROUGH SATURDAY...A DEEP LAYER ATLANTIC RIDGE SHOULD REMAIN ACROSS SOUTH CENTRAL FLORIDA TODAY AND TONIGHT. WATER VAPOR IMAGES SHOW A RATHER DRY AIRMASS BEING ADVECTED WESTWARD ACROSS THE NRN BAHAMAS AND THE SOUTHERN PORTIONS OF THE PENINSULA BY THE DEEP EASTERLY FLOW AROUND THE BASE OF THIS RIDGE. WL EXPECT THIS DRY AIR, COMBINED WITH SUBSIDENCE ALOFT, TO KEEP PRECIP ACTIVITY TO A MINIMUM ACROSS MOST AREAS TODAY. HOWEVER, LOCAL BREEZES AND DIURNAL HEATING COULD STILL LEAD TO THE DEVELOPMENT OF A FEW SHWRS/TSTMS ACROSS INTERIOR PORTIONS LATER THIS AFTERNOON. WL EXPECT THIS TO BE FOCUSED MORE TOWARD THE WESTERN INTERIOR AND WEST OF LAKE OKEECHOBEE. PLENTY OF SUNSHINE TODAY WILL ALSO LEAD TO AFTERNOON TEMPS SOARING INTO THE LOWER TO MID 90S WITH HEAT INDICES AT OR ABOVE 100 DEGREES ACROSS MOST AREAS, EXCEPT FOR THE IMMEDIATE EAST COAST. A RATHER ACTIVE TROPICAL WAVE WAS LOCATED ACROSS THE CENTRAL CARIBBEAN SEA EARLIER THIS MORNING MOVING WEST AT AROUND 10-15 KTS. AN UPPER LOW WAS ALSO INDICATED JUST NW OF JAMAICA AND INTERACTING WITH THE WAVE. A LARGE ENVELOP OF MOISTURE WAS ASSOCIATED WITH BOTH SYSTEMS. MOISTURE SHOULD BEGIN TO INCREASE GRADUALLY OVER S. FLORIDA AS THE UPPER LOW MOVES TO THE WESTERN TIP OF CUBE FRIDAY, BUT WILL BE FURTHER ENHANCED AS THE TROPICAL WAVE MOVES ACROSS THE LOCAL AREA FRI NIGHT AND SATURDAY. DUE TO THE NATURE OF THESE SYSTEMS AND THE COMPLEXITY OF THE INTERACTIONS BETWEEN UPPER LOWS AND TROPICAL WAVES (BASED ON PAST EXPERIENCE), DECIDED TO INCREASE THE CHANCES OF RAIN WITH CAUTION FOR BOTH FRIDAY AND SATURDAY AND NOT GO AS HIGH AS GFS. IF THE RIGHT COMBINATION, ENHANCED LOW LEVEL CONVERGENCE ASSOCIATED WITH THE WAVE AND UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE LOW, COMES TO PLAY, THE CHANCES FOR RAIN COULD BE SIGNIFICANTLY HIGHER. LONG TERM...SUNDAY THROUGH WEDNESDAY...AN UPPER RIDGE SHOULD BEGIN TO BUILD ACROSS THE REGION WHILE A LOW LEVEL ATLANTIC RIDGE IS EXPECTED TO BUILD WESTWARD. THIS WILL TO LIMIT THE PRECIP ACTIVITY BY WAY OF MID/UPPER LVL SUBSIDENCE AND WILL TEND TO FOCUS AFTERNOON SHWRS/TSTMS MORE TOWARD INTERIOR AND WESTWARD PORTIONS OF S. FLORIDA. NIGHTTIME AND EARLY MORNING PRECIP ACTIVITY COULD ALSO OCCUR ALONG EASTERN AREAS. MARINE...A LIGHT TO MODERATE SE FLOW SHOULD PREVAIL THROUGH THE END OF THE WEEK WITH A SHIFT TO MORE SOUTHERLY BY THE WEEKEND. SEAS ARE EXPECTED TO BE BELOW 4 FT THROUGH THE PERIOD. HOWEVER...BOTH SEAS AND WINDS COULD BE SIGNIFICANTLY HIGHER IN THE VICINITY OF SHOWERS AND THUNDERSTORMS...ESPECIALLY FRI NIGHT AND SATURDAY AS THE TROPICAL WAVE MOVES THROUGH. FIRE WEATHER...NO CONCERNS AT THIS TIME. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 79 88 77 90 / 20 70 50 60 FORT LAUDERDALE 80 88 79 90 / 30 70 50 60 MIAMI 79 88 78 90 / 30 70 50 60 NAPLES 76 89 76 91 / 20 50 30 50 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...57/DG AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION
NWS MIAMI FL
1043 AM EDT THU AUG 9 2012 .UPDATE...THE LATEST HRRR SHOWS QUITE A BIT OF CONVECTION DEVELOPING OVER THE INTERIOR AND ESPECIALLY THE GULF COAST/NAPLES AREA THIS AFTERNOON. THE MIAMI SOUNDING THIS MORNING SHOWS SUFFICIENT MOISTURE FOR CONVECTION...WITH A PWAT OF 1.62 INCHES AND THE DRIEST AIR IN THE MID LEVELS. HAVE INCREASED THE COVERAGE OF SHOWERS/TSTORMS FOR THE INTERIOR AND GULF COAST...WITH THE HIGHEST POPS ACROSS THE NAPLES AREA. WEAK LAPSE RATES ARE PRESENT BUT GIVEN STRONG HEATING AND MID LEVEL DRY AIR...A FEW STRONG STORMS ARE POSSIBLE WHERE CONVERGENCE IS MAXIMIZED WHICH LOOKS TO BE ACROSS THE GREATER NAPLES AREA LATE THIS AFTERNOON. STRONG WIND GUSTS TO AROUND 50 MPH WOULD BE THE MAIN CONCERN IN THE STRONGEST STORMS...AS WELL AS FREQUENT LIGHTNING. /GREGORIA && .PREV DISCUSSION... /ISSUED 655 AM EDT THU AUG 9 2012/ AVIATION... EASTERLY FLOW EXPECTED TO CONTINUE THROUGH THE PERIOD AT ALL EAST COAST SITES WITH VFR CONDITIONS. KEPT VCTS MENTION AT KAPF AS A WEAK GULF COAST SEA BREEZE COULD DEVELOP DURING THE EARLY AFTERNOON HOURS RESULTING IN SCATTERED SHRA/TSTMS. PREV DISCUSSION... /ISSUED 326 AM EDT THU AUG 9 2012/ SHORT TERM...TODAY THROUGH SATURDAY...A DEEP LAYER ATLANTIC RIDGE SHOULD REMAIN ACROSS SOUTH CENTRAL FLORIDA TODAY AND TONIGHT. WATER VAPOR IMAGES SHOW A RATHER DRY AIRMASS BEING ADVECTED WESTWARD ACROSS THE NRN BAHAMAS AND THE SOUTHERN PORTIONS OF THE PENINSULA BY THE DEEP EASTERLY FLOW AROUND THE BASE OF THIS RIDGE. WL EXPECT THIS DRY AIR, COMBINED WITH SUBSIDENCE ALOFT, TO KEEP PRECIP ACTIVITY TO A MINIMUM ACROSS MOST AREAS TODAY. HOWEVER, LOCAL BREEZES AND DIURNAL HEATING COULD STILL LEAD TO THE DEVELOPMENT OF A FEW SHWRS/TSTMS ACROSS INTERIOR PORTIONS LATER THIS AFTERNOON. WL EXPECT THIS TO BE FOCUSED MORE TOWARD THE WESTERN INTERIOR AND WEST OF LAKE OKEECHOBEE. PLENTY OF SUNSHINE TODAY WILL ALSO LEAD TO AFTERNOON TEMPS SOARING INTO THE LOWER TO MID 90S WITH HEAT INDICES AT OR ABOVE 100 DEGREES ACROSS MOST AREAS, EXCEPT FOR THE IMMEDIATE EAST COAST. A RATHER ACTIVE TROPICAL WAVE WAS LOCATED ACROSS THE CENTRAL CARIBBEAN SEA EARLIER THIS MORNING MOVING WEST AT AROUND 10-15 KTS. AN UPPER LOW WAS ALSO INDICATED JUST NW OF JAMAICA AND INTERACTING WITH THE WAVE. A LARGE ENVELOP OF MOISTURE WAS ASSOCIATED WITH BOTH SYSTEMS. MOISTURE SHOULD BEGIN TO INCREASE GRADUALLY OVER S. FLORIDA AS THE UPPER LOW MOVES TO THE WESTERN TIP OF CUBE FRIDAY, BUT WILL BE FURTHER ENHANCED AS THE TROPICAL WAVE MOVES ACROSS THE LOCAL AREA FRI NIGHT AND SATURDAY. DUE TO THE NATURE OF THESE SYSTEMS AND THE COMPLEXITY OF THE INTERACTIONS BETWEEN UPPER LOWS AND TROPICAL WAVES (BASED ON PAST EXPERIENCE), DECIDED TO INCREASE THE CHANCES OF RAIN WITH CAUTION FOR BOTH FRIDAY AND SATURDAY AND NOT GO AS HIGH AS GFS. IF THE RIGHT COMBINATION, ENHANCED LOW LEVEL CONVERGENCE ASSOCIATED WITH THE WAVE AND UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE LOW, COMES TO PLAY, THE CHANCES FOR RAIN COULD BE SIGNIFICANTLY HIGHER. LONG TERM...SUNDAY THROUGH WEDNESDAY...AN UPPER RIDGE SHOULD BEGIN TO BUILD ACROSS THE REGION WHILE A LOW LEVEL ATLANTIC RIDGE IS EXPECTED TO BUILD WESTWARD. THIS WILL TO LIMIT THE PRECIP ACTIVITY BY WAY OF MID/UPPER LVL SUBSIDENCE AND WILL TEND TO FOCUS AFTERNOON SHWRS/TSTMS MORE TOWARD INTERIOR AND WESTWARD PORTIONS OF S. FLORIDA. NIGHTTIME AND EARLY MORNING PRECIP ACTIVITY COULD ALSO OCCUR ALONG EASTERN AREAS. MARINE...A LIGHT TO MODERATE SE FLOW SHOULD PREVAIL THROUGH THE END OF THE WEEK WITH A SHIFT TO MORE SOUTHERLY BY THE WEEKEND. SEAS ARE EXPECTED TO BE BELOW 4 FT THROUGH THE PERIOD. HOWEVER...BOTH SEAS AND WINDS COULD BE SIGNIFICANTLY HIGHER IN THE VICINITY OF SHOWERS AND THUNDERSTORMS...ESPECIALLY FRI NIGHT AND SATURDAY AS THE TROPICAL WAVE MOVES THROUGH. FIRE WEATHER...NO CONCERNS AT THIS TIME. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 89 79 89 75 / 20 20 50 40 FORT LAUDERDALE 91 80 88 75 / 20 20 50 50 MIAMI 91 79 89 76 / 20 20 50 50 NAPLES 93 77 91 76 / 50 20 40 30 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
337 AM EDT THU AUG 9 2012 .DISCUSSION... TODAY-TONIGHT... CENTRAL FL IS UNDER THE DIRECT INFLUENCE OF A MID/UPR LVL COL AS SEEN BY THE LATEST RAP ANALYSIS OF THE H85-H50 AND H30-H20 STREAMLINES. THE RESULTING STEERING FLOW IS QUITE WEAK AND HOLDS LITTLE POTENTIAL FOR PUSHING ANY SIG MID LVL ENERGY INTO THE TORPID AIRMASS THAT CURRENTLY BLANKETS THE CWA: BOTH THE H85-H50 AND H85-H30 VORTICITY FIELDS SHOW MINIMAL LIFT POTENTIAL. LOW AND MID LVL MOISTURE TRAPPED UNDERNEATH THE COL WITH H100-H70 AND H85-H50 MEAN RH VALUES LARGELY ABV 75PCT OVR THE NW HALF OF THE CWA. MID LVL THERMAL RIDGE HAS WEAKENED A TOUCH OVER THE PAST 24HRS THOUGH H70 TEMPS REMAIN ON THE ORDER OF 9C. COMBINED WITH H50 TEMPS BTWN -6C AND -7C...THE MID LVL LAPSE RATES ARE MODERATELY UNSTABLE AT BEST. A 50KT H30-H20 JET STREAK LIFTING UP THE ERN SEABOARD WILL GENERATE WEAK UPR LVL DIVERGENCE N OF THE CAPE THIS MORNING...BUT THIS WILL DIMINISH THRU THE DAY AS THE JET PULLS AWAY FROM THE FL PENINSULA. THE CURRENT WX PATTERN IS TYPICAL OF MID SUMMER...THOUGH LINGERING DRY AIR OVER THE SE HALF OF THE CWA WILL RESULT IN BLO AVG PRECIP COVERAGE. MESOSCALE BNDRY INTERACTION ONCE AGAIN WILL BE REQUIRED TO SPARK DIURNAL CONVECTION. ISOLD COVERAGE OVER THE SE HALF OF THE CWA DUE TO DRIER AIR AND EARLIER FORMATION OF THE EAST COAST SEA BREEZE...SCT COVERAGE INTERIOR DUE TO DEEPER MOISTURE AND WARMER MAX TEMPS. MOST OF THE ACTIVITY WILL BURN OUT BY SUNSET. WILL KEEP ISOLD TSRAS THRU MID EVENING OVR THE NRN CWA TO ACCOUNT FOR LINGERING POCKETS OF ENERGY. MAV MOS TEMPS CONTINUE ON THE HIGH SIDE GIVE THE MID/UPR LVL MOISTURE BAND AND EARLY FORMATION OF THE SEA BREEZE...WILL CONTINUE TO KEEP MAX TEMPS IN THE U80S/L90S ALONG THE COAST AND L/M90S INTERIOR. LIGHT SRLY BREEZE WILL KEEP MIN TEMPS IN THE L/M70S. FRI-SAT...LITTLE CHANGE FROM PREVIOUS GFS RUNS IS INDICATED. UPPER LEVEL INVERTED TROUGH WILL PUSH WEST OF THE AREA/WEAKEN ON FRI. THIS WILL CAUSE SUBSIDENCE TO DIMINISH. THEN ON SAT THE TAIL END OF A TROUGH IN THE WESTERLIES WILL NOSE INTO THE EASTERN GULF OF MEXICO...WHICH IS USUALLY A FAVORABLE SYNOPTIC PATTERN FOR INCREASED POPS. SOUTHEAST LOW LEVEL FLOW WILL START TO TAP HIGHER MOISTURE ON FRI SO POPS WILL RETURN TO SCATTERED ACROSS THE AREA. THE HIGHEST VALUES SHOULD BE OVER THE SOUTH WHERE DEEPEST MOISTURE IS PROGGED. ON SAT AROUND 2 INCHES OF PRECIPITABLE WATER IS INDICATED AREAWIDE. WITH THE TROUGH ALOFT MOVING ACROSS THE SOUTHEAST STATES THERE SHOULD BE SOME WESTERLY STEERING LEVEL FLOW...ALBEIT RATHER WEAK. SO POPS WILL BE AT LEAST 40 PERCENT AREAWIDE. GREATER BOUNDARY INTERACTIONS ACROSS THE SOUTH SHOULD CAUSE HIGHER VALUES AROUND 50 PERCENT. THESE VALUES ARE CLOSE TO THE LATEST MOS. NOT CONFIDENT ENOUGH IN THE MODEL HANDLING OF MOISTURE TO GO HIGHER ON POPS YET. SUN-THU...GFS INDICATES TROUGHING ALOFT OVER THE EASTERN PART OF THE COUNTRY WITH ASSOCIATED SURFACE FRONTAL TROUGH KEEPING SURFACE RIDGE ACROSS THE CENTRAL TO SOUTH CENTRAL FLORIDA PENINSULA. THIS SHOULD ALLOW A WEAK WESTERLY STEERING FLOW TO CONTINUE ACROSS THE AREA FOR MOST OF THE PERIOD. NEAR TO A LITTLE ABOVE NORMAL PRECIPITABLE WATER IS INDICATED. WITH 700 MB TEMPS REMAINING 9 TO 10 DEGREES CELSIUS...AGREE WITH MOS POPS WHICH REMAIN AT OR A LITTLE BELOW CLIMO...30 TO 40 PERCENT. WITH CONVECTION LIKELY TO INITIATE A LITTLE LATER THAN NORMAL...MAX TEMPS WILL CONTINUE A FEW DEGREES HOTTER THAN NORMAL...WITH 90 TO LOWER 90S ALONG THE COAST AND MID 90S INLAND. && .AVIATION... ALL SITES VFR UNLESS OTHERWISE NOTED: THRU 09/13Z...LCL MVFR CIGS/IFR VSBYS IN BR CSTL SITES S OF KMLB. BTWN 09/15Z-09/17Z... DVLPMNT OF THE EAST COAST SEA BREEZE S OF KTIX WILL FORCE A SFC WNDSHFT FM S/SE TO E AOB 10KTS...SEA BREEZE WILL WORK ITS WAY UP THE COAST N OF KTIX THRU MID AFTN...FORCING A WNDSHFT FM S/SW TO SE. BTWN 08/18Z-08/24Z...SCT MVFR SHRAS/IFR TSRAS N OF KISM-KTIX...ISOLD MVFR SHRAS/IFR TSRAS S OF KISM-KTIX. && .MARINE... TODAY-TONIGHT...ATLC RIDGE AXIS BISECTING THE FL PENINSULA WILL GENERATE A GENTLE TO MODERATE S/SE BREEZE S OF CAPE CANAVERAL...S/SW N OF CAPE CANAVERAL. THE EAST COAST SEA BREEZE WILL FORM BY MIDDAY S OF THE CAPE...FORCING SFC/BNDRY LYR WNDS NEAR THE COAST TO BACK TO THE E. SEA BREEZE WILL DVLP NWD THRU MID AFTN WITH WINDS BACKING TO THE SE BTWN THE CAPE AND FLAGLER BEACH. SEAS AOB 2FT NEARSHORE AND 2-3FT OFFSHORE. SCT AFTN TSRAS MOVG OFFSHORE N OF THE CAPE. FRI-MON...THE ATLANTIC SURFACE RIDGE AXIS IS PROGGED TO EXTEND ACROSS THE CENTRAL TO SOUTH CENTRAL PENINSULA. THIS WILL CONTINUE THE SOUTHWEST TO SOUTH/SOUTHEAST WIND FLOW WITH SPEEDS 10 KNOTS OR LESS...EXPECT FOR A SLIGHT INCREASE TO 10-15 KNOTS FRI EVENING. INCREASING MOISTURE AND A WEAK WESTERLY STEERING LEVEL WIND FLOW SHOULD BRING SOME OF THE AFTERNOON/EVENING STORMS BACK ACROSS THE COAST AND INTO THE NEAR SHORE ATLANTIC ON MOST OF THE DAYS. && .PRELIMINARY POINT TEMPS/POPS... DAB 90 75 92 74 / 30 20 30 20 MCO 93 76 94 74 / 30 20 30 20 MLB 89 76 90 74 / 20 10 30 20 VRB 91 74 90 74 / 20 10 40 30 LEE 92 77 95 75 / 30 20 30 20 SFB 93 77 94 75 / 30 20 30 20 ORL 93 76 94 76 / 30 20 30 20 FPR 91 74 90 73 / 20 10 40 30 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM/AVIATION...BRAGAW LONG TERM....LASCODY
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
426 AM EDT THU AUG 9 2012 .SYNOPSIS... ATLANTIC HIGH PRESSURE WILL REMAIN OFFSHORE THROUGH LATE WEEK...WHILE A WEAK TROUGH OF LOW PRESSURE PERSISTS INLAND. A STRONG LOW PRESSURE SYSTEM WILL DEVELOP TO THE NORTH ON FRIDAY...WHILE AN ASSOCIATED COLD FRONT APPROACHES OVER THE WEEKEND. THE FRONT WILL LIKELY STALL OVER OR NEAR THE AREA...BEFORE DISSIPATING BY THE MIDDLE OF NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... PRE-DAWN...OVERNIGHT WE HAVE BEEN WATCHING AN E-W BOUNDARY MAINTAIN CONVECTION JUST OFFSHORE. THIS BOUNDARY EXTRAPOLATES THROUGH THE SAVANNAH RIVER BUT ONLY SPOTTY LAND BASED SHOWERS DESPITE SOME DECENT INSTABILITY NOTED ON THE SPC RUC MESO ANALYSIS AT 08Z. UPSTREAM CONVECTION OVER THE CSRA AND S CAROLINA UPSTATE IN RESPONSE TO A WEAK SHORT WAVE AND A REGION OF UPPER DIVERGENCE. CANNOT RULE OUT AN ISOLATED SHOWER OR STORM ACROSS THE FORECAST AREA BUT MOST AREAS TO START THE DAY DRY. SOME AREAS WILL SEE PATCHY FOG WITH TEMPS AND DEW POINTS EQUIVALENT AND LOW LEVELS SATURATED. TODAY...A WEAK MID/UPPER TROUGH LINGERS ACROSS THE REGION WITH ATMOSPHERIC MOISTURE AND STABILITY PROFILES FAIRLY TYPICAL FOR THIS TIME OF YEAR. LAST NIGHT/S CONVECTION OVER THE SE MIDLANDS PUSHED A FAIRLY SUBSTANTIAL OUTFLOW BOUNDARY INTO INLAND AREAS TO THE NW OF BEAUFORT AND W OF CHARLESTON AND THE OTHER BOUNDARY IN SE GEORGIA UNLIKELY TO MOVE MUCH TODAY. DIFFERENTIAL HEATING THIS MORNING AND PRESENCE OF SMALL SCALE BOUNDARIES SHOULD MAKE FOR SOME FAIR DESTABILIZATION THIS AFTERNOON WITH PULSE CONVECTION BECOMING SCATTERED TO THE W OF I-95 AND MAINLY ISOLATED ALONG COASTAL SOUTH CAROLINA. SATELLITE IMAGERY SHOWS BETTER CHANCES FOR SOME MORNING SUNSHINE MANY AREAS AND THIS SHOULD RESULT IN WARMER TEMPS 89-92 DEGREES TODAY BEFORE SHOWERS AND STORMS INITIATE. BEST INSTABILITY PARAMETERS SUGGEST STRONGER TSTMS WILL END UP OVER INLAND AREAS MAINLY ALONG AND W OF I-95 AND PROBABLY N OF I-16. ISOLATED SEVERE WEATHER MAY BE POSSIBLE LOCALLY WITH DOWNDRAFT CAPES OVER 1000 J/KG TO START THE DAY TO THE N OF I-16. STEERING FLOW WILL BE INITIALLY BE SLUGGISH ACROSS THE AREA. TO THE S OF I-16...PWATS ARE HIGHER AND CONVECTIVE INITIATION WILL LIKELY OCCUR SOMEWHAT EARLIER IN THE DAY. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... MODELS IN GOOD AGREEMENT ON DRIVING A FAIRLY SIGNIFICANT MID LEVEL TROUGH INTO THE GEORGIA AND THE CAROLINAS TONIGHT AND THIS FEATURE WILL LIKELY MAINTAIN SCATTERED CONVECTIVE RAINS ACROSS THE FORECAST AREA THROUGH THE EVENING AND INTO THE OVERNIGHT HOURS. WEAK HEIGHT FALLS SUGGEST CONVECTION COULD REMAIN STRONG INLAND IN MULTICELL CLUSTERS WITH SCATTERED SHOWERS AND TSTMS DEVELOPING TOWARD COASTAL AREAS OVERNIGHT... ESPECIALLY IF AIR MASS GOES UNTAPPED FROM SEA BREEZE CONVECTION THIS AFTERNOON. FRIDAY AND SATURDAY...A STRONG UPPER LOW SYSTEM WILL ROTATE INTO THE OHIO VALLEY REGION ON FRIDAY...PROVIDING THE NECESSARY ENERGY TO DEVELOP AN UNSEASONABLY STRONG CO-LOCATED SURFACE LOW. THE STACKED LOW SYSTEM WILL SLOWLY MEANDER FARTHER TO THE NORTH/NORTHEAST FRIDAY INTO SATURDAY...WHILE THE UPPER TROUGH STRETCHING DOWN THE EAST COAST AMPLIFIES ACCORDINGLY. A TRAILING COLD FRONT WILL MAKE STEADY PROGRESS TOWARD THE COASTLINE THROUGH THE DAYTIME HOURS SATURDAY...AIDED BY A SERIES OF SHORTWAVES DOWNSTREAM OF THE TROUGH AXIS JUST TO THE WEST. UPPER LEVEL SUPPORT WITHIN THE RIGHT REAR ENTRANCE OF A STRENGTHENING UPPER JET...COMBINED WITH SHORTWAVE ENERGY AND LOW LEVEL CONVERGENCE FROM THE APPROACHING COLD FRONT...WILL ENHANCE DEEP MOISTURE ACROSS THE REGION. AS A RESULT...SHOWER/THUNDERSTORM POTENTIAL WILL INCREASE FRIDAY AND SATURDAY. WILL CONTINUE TO ADVERTISE MOST SIGNIFICANT CONVECTIVE COVERAGE ON SATURDAY...WHEN THE FRONT WILL BE CLOSEST TO THE FORECAST AREA AND UPPER LEVEL SUPPORT WILL BE MAXIMIZED. HAVE INDICATED POPS GENERALLY IN THE 40 PERCENT RANGE FRIDAY AND FRIDAY NIGHT...INCREASING TO AROUND 50 PERCENT BY SATURDAY. CONSIDERING THE UNSEASONABLY STRONG SYNOPTIC LEVEL FEATURES AT BOTH THE SURFACE AND ALOFT...AS WELL AS TYPICAL SUMMERTIME HEATING AND INSTABILITY...WILL NEED TO MONITOR MODEL TRENDS AND STORM PREDICTION CENTER OUTLOOKS FOR SEVERE WEATHER POTENTIAL. HIGH TEMPERATURES FRIDAY AND SATURDAY WILL BE SUPPRESSED SLIGHTLY BY THICKENING CLOUD COVER AND DECREASING HEIGHTS ALOFT. EXPECT TEMPERATURES TO PEAK IN THE UPPER 80S TO AROUND 90 DEGREES BOTH AFTERNOONS...LIKELY COOLEST ON SATURDAY WHEN RAIN COVERAGE WILL BE GREATEST. SUNDAY...AS THE UPPER LOW CENTER CONTINUES TO LIFT INTO EASTERN CANADA...THE EAST COAST TROUGH WILL BECOME LESS AMPLIFIED TO THE SOUTH. THIS WILL CAUSE THE COLD FRONT TO STALL AND BEGIN TO DISSIPATE OVER OR NEAR THE FORECAST AREA EARLY NEXT WEEK. WEAK HIGH PRESSURE WILL ATTEMPT TO BUILD FROM THE WEST AND INTRODUCE DRIER AIR INTO THE SOUTHEAST STATES. EXPECT PRECIPITATION POTENTIAL TO DECREASE AS A RESULT...AND HAVE LIMITED POPS INTO THE SLIGHT CHANCE TO LOW CHANCE RANGE ACCORDINGLY. WILL INDICATE BEST CONVECTIVE COVERAGE ACROSS SOUTHEAST GEORGIA ZONES CLOSEST TO LINGERING MOISTURE ALONG THE SOUTHERN BOUNDARY OF THE DISSIPATING FRONT. TEMPERATURES ON SUNDAY WILL REBOUND INTO THE LOWER 90S AWAY FROM THE LOCALLY COOLER COASTLINE DUE TO INCREASING INSOLATION AND A SLIGHT INCREASE IN HEIGHTS ALOFT. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... A LESS AMPLIFIED UPPER LEVEL PATTERN IS EXPECTED MONDAY THROUGH THE MIDDLE OF NEXT WEEK. THE SURFACE PATTERN WILL REMAIN RELATIVELY WEAK AS WELL...WITH SUBTLE HIGH PRESSURE SETTLING OVER THE REGION MONDAY AND TUESDAY. MEDIUM RANGE MODELS ARE IN SOME DISAGREEMENT REGARDING THE TRACK OF SHORTWAVE ENERGY WITHIN THE BASE OF A WEAK UPPER TROUGH THAT WILL TAKE SHAPE ALONG THE EAST COAST LATE TUESDAY INTO THURSDAY. HAVE LIMITED PRECIPITATION CHANCES ON MONDAY AND TUESDAY...LACKING NOTABLE DEEP MOISTURE AND UPPER LEVEL SUPPORT. HAVE THEN INCREASED POPS SLIGHTLY FOR WEDNESDAY AND THURSDAY TO ACCOUNT FOR THE FORMATION OF THE BROAD UPPER TROUGH ALONG THE EAST COAST AND AN ASSOCIATED SURFACE WAVE OF LOW PRESSURE. STILL EXPECT CONVECTION TO MAINTAIN A MORE SEASONAL DIURNAL DEVELOPMENT PATTERN...WITH BEST COVERAGE DURING THE FAVORED AFTERNOON/EVENING HOURS EACH DAY. HIGH TEMPERATURES WILL GENERALLY RANGE IN THE LOWER 90S AWAY FROM THE LOCALLY COOLER COASTLINE. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... PATCHY FOG IS POSSIBLE AROUND THE COASTAL CORRIDOR AROUND DAYBREAK THIS MORNING AS HIGH CLOUDS WERE MAINLY THIN. OTHERWISE MAINLY VFR CONDITIONS EXPECTED OUTSIDE OF IMPACTS FROM DIURNAL CONVECTION THIS AFTERNOON AND EVENING. CONDITIONS APPEAR TO FAVOR KSAV FOR SLIGHTLY HIGHER CHANCES AFTER 18Z AND WE CONTINUED THE PROB30 MENTIONS AND LINGERED VCTS INTO THU EVENING. AT KCHS...TSTMS PROBABLY MORE HIT OR MISS DURING PEAK HEATING TODAY. WILL NEED TO WATCH AFTER FOR ADDITIONAL TSTMS LOOMING TO THE W AFTER SUNSET AT BOTH TERMINALS. EXTENDED AVIATION OUTLOOK... CONDITIONS WILL REMAIN UNSETTLED THROUGH THE UPCOMING WEEKEND. BRIEF PERIODS OF MVFR OR LOWER CONDITIONS WILL BE POSSIBLE WITH ANY SHOWERS AND THUNDERSTORMS...MAINLY DURING THE AFTERNOON/EVENING HOURS. && .MARINE... NO SIGNIFICANT CHANGE TO SYNOPTIC PATTERN OR FORECAST CONDITIONS TODAY WITH SW FLOW 10-15 KT EARLY AND LATE AND CLOSE TO 10 KT AROUND MIDDAY. LOW LEVEL JET WILL INCREASE TONIGHT AND WE SHOULD SEE WINDS INCREASE TO NEAR 15 KT WITH GUSTS TO 20 KT AT TIMES AND SEAS BUILD FROM 2 FT TO 3-4 FT LATE. FRIDAY THROUGH MONDAY...SOUTH TO SOUTHWEST FLOW WILL CONTINUE ACROSS THE LOCAL WATERS UNDER THE INFLUENCE OF THE SUBTROPICAL HIGH TO THE EAST. AS A COLD FRONT APPROACHES FROM THE NORTHWEST EARLY THIS WEEKEND...THE LOW LEVEL FLOW WILL INCREASE WITH THE TIGHTENING PRESSURE GRADIENT. WINDS COULD SURGE CLOSE TO MARGINAL SMALL CRAFT ADVISORY LEVELS FRIDAY INTO EARLY SATURDAY...BUT STILL EXPECT CONDITIONS TO REMAIN JUST BELOW CRITERIA AT THIS POINT. SINCE THE FRONT IS EXPECTED TO DISSIPATE WITHOUT A CLEAR PASSAGE ACROSS THE MARINE ZONES...WINDS WILL MAINTAIN A SOUTHERLY COMPONENT INTO EARLY NEXT WEEK. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
637 PM EDT THU AUG 9 2012 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 226 PM EDT THU AUG 9 2012 LOW PRESSURE OVER SOUTHEASTERN ILLINOIS WILL PUSH NORTHEAST TONIGHT...DRAGGING A COLD FRONT ACROSS CENTRAL INDIANA THIS EVENING. THIS IN COMBINATION WITH DAYTIME HEATING WILL ALLOW FOR SCATTERED THUNDERSTORMS TO DEVELOP LATE THIS AFTERNOON AND THIS EVENING ALONG AND AHEAD OF THE FRONT. THE LOW WILL SLOWLY PUSH TO THE EASTERN GREAT LAKES ON FRIDAY AND SATURDAY...ALLOWING COOLER AIR ON NORTHWEST WINDS AND DRY WEATHER TO ARRIVE IN CENTRAL INDIANA FOR THE WEEKEND. COOLER WEATHER IS EXPECTED MUCH OF NEXT WEEK. A LOW PRESSURE SYSTEM PASSING TO THE SOUTH ON WEDNESDAY AND A COLD FRONT APPROACHING ON THURSDAY NIGHT AND FRIDAY WILL BRING OUR NEXT CHANCES FOR SHOWERS AND STORMS. && .NEAR TERM /TONIGHT/... ISSUED AT 226 PM EDT THU AUG 9 2012 SURFACE ANALYSIS EARLY THIS AFTERNOON SHOWS LOW PRESSURE NEAR STL WITH A COLD FRONT EXTENDING SW INTO NW ARKANSAS AND A WARM FRONT STRETCHING SE ACROSS SOUTHERN ILLINOIS AND SOUTHERN INDIANA. VISIBLE PICTURE SHOW PLENTY OF CLOUD COVER ACROSS CENTRAL INDIANA...HOWEVER CLEARING WAS IN PLACE ACROSS CENTRAL AND SOUTHERN ILLINOIS. DEW POINT TEMPS REMAINED MOIST IN THE 60S. RADAR SHOWS TSRA DEVELOPING OVER CENTRAL KENTUCKY AND SW OHIO. MAIN FORECAST CHALLENGE WILL BE POPS. AS THE LOW PRESSURE SYSTEM NEAR STL IS EXPECTED TO TRACK NE TONIGHT MORE FAVORABLE CONDITIONS ARE EXPECTED OVER ILLINOIS FOR CONVECTION DEVELOPMENT. LIFTED INDICES REMAIN NEGATIVE THIS AFTERNOON AHEAD OF THE FRONT WITH FAVORABLE CAPE IN EXCESS OF 1300 J/KG. HRRR DEVELOPS BEST CONVECTION ALONG THE COLD FRONT WHICH SHOULD PASS ACROSS CENTRAL INDIANA AFTER 00Z. 0-3KM SHEAR AXIS OF NEAR 25-30 KNTS PUSH ACROSS THE STATE WITH ET FRONT AS WELL. THUS WILL KEEP TSRA MENTION WITH LIKELY OR BETTER POPS FOR TONIGHT. AS THE FRONT DEPARTS TOWARD 12Z FORECAST SOUNDINGS SHOW MUCH DRIER AIR ARRIVING. WILL TREND POPS DOWNWARD AFTER 06Z. AS FOR LOWS...WILL USE A BLEND OF MAVMOS AND METMOS GIVEN THE CHANGE IN AIRMASS. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... ISSUED AT 226 PM EDT THU AUG 9 2012 MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE OVERALL PATTERN AND WILL USE A BLEND. MAIN FORECAST CHALLENGE WILL BE TEMPS THROUGH THE PERIOD. NAM/GFS AGREE THAT A DEEP UPPER LOW EXPECTED TO BE OVER NORTHERN INDIANA ON FRIDAY WILL SLOWLY DRIFT NORTHEAST TO THE GREAT LAKES. ABUNDANT CLOUD COVER IS EXPECTED TO REMAIN ACROSS THE AREA ON FRIDAY AS THE LOW DRIFTS TO THE NORTH. TIME HEIGHT SECTIONS SHOW GOOD LOWER LEVEL MOISTURE. FURTHERMORE FORECAST SOUNDINGS SHOW CONVECTIVE TEMPERATURES IN THE LOWER 70S THAT COULD RESULT IN SOME ISOLATED POP UP AFTERNOON RAIN SHOWERS. WILL TREND HIGHS COOLER THAN MAVMOS GIVEN THE EXPECTED CLOUDS AND THE COLD AIR ADVECTION. LINGERING CLOUDS AND ANY ISOLATED SHRA WILL DISSIPATE ON FRIDAY NIGHT AS UPPER LOW PULLS NORTHEAST AND ANY DAYTIME HEATING WANES. EVEN BETTER DRYING APPEARS IN THE FORECAST SOUNDINGS IN ON FRIDAY NIGHT AND SATURDAY...CONTINUING INTO SATURDAY NIGHT AS HIGH PRESSURE REMAINS ACROSS THE AREA. GIVEN THE COLD AIR ADVECTION AS 850MB TEMPS FALL NEAR 10C WILL TREND HIGHS AND LOWS COOLER THAN MAVMOS...WITH MOSTLY CLEAR NIGHTS AND A SUNNY SATURDAY. SURFACE HIGH REMAINS IN CONTROL IN SUNDAY ACROSS THE OHIO VALLEY...HOWEVER ALOFT A SHORT WAVE IS APPROACHING AND PUSHING THROUGH INDIANA. SURFACE FLOW DOES NOT APPEAR TO OPEN AND ALLOW FOR THE ADDITION OF GULF MOISTURE. THUS FOR NOW WILL HOLD OFF ON POPS FOR SUNDAY UNTIL BETTER CONFIDENCE IS REVEALED IN LOWER LEVEL MOISTURE....BUT WILL INCREASE CLOUD COVERAGE. && .LONG TERM /MONDAY THROUGH THURSDAY/... ISSUED AT 226 PM EDT THU AUG 9 2012 ENSEMBLES SUGGEST A FAIRLY PROGRESSIVE FLOW ACROSS THE NORTHERN PARTS OF THE COUNTRY...WHILE THE SUB TROPICAL RIDGE HOLDS FROM THE SOUTHERN ROCKIES EASTWARD ACROSS THE GULF COAST STATES. ANOTHER UPPER DISTURBANCE IS EXPECTED TO DROP INTO THE GREAT LAKES AND OHIO VALLEY EARLY NEXT WEEK...AND THEN LIFT OFF TO THE EAST BY THE MIDDLE OF NEXT WEEK. ENSEMBLES SUGGEST THE BEST THREAT FOR PRECIPITATION WITH THIS SYSTEM WILL BE MONDAY AND MONDAY NIGHT. WILL GO WITH CHANCE POPS AT THOSE TIMES. HEIGHTS ARE EXPECTED TO RISE TOWARDS THE MIDDLE OF NEXT WEEK AS TROUGH LIFTS OFF TO THE EAST...SO WILL CONTINUE WITH A DRY FORECAST FOR TUESDAY AND WEDNESDAY. BY THURSDAY...THERE ARE INDICATIONS THAT THE HEAT RIDGE MAY TRY TO BUILD BACK INTO THE SOUTHERN PLAINS. THE ENSEMBLES SUGGEST ANOTHER DISTURBANCE MAY RIDE OVER THE DEVELOPING RIDGE INTO THE LOCAL AREA BY THURSDAY. WILL CONTINUE WITH CHANCE POPS AT THAT TIME. && .AVIATION /DISCUSSION FOR THE 100000Z TAF ISSUANCE/... ISSUED AT 637 PM EDT THU AUG 9 2012 THUNDERSTORM ACTIVITY WILL BE INCREASING THIS EVENING AS A COLD FRONT DROPS SOUTHEAST ACROSS THE TERMINALS AND AN UPPER LOW PIVOTS SOUTHEAST TO NORTHERN ILLINOIS AND THEN NORTHERN INDIANA. WILL GO WITH TEMPO THUNDERSTORM GROUPS THROUGH 05Z AT HUF AND LAF AND IND AND BMG TIL 06Z. WILL ALSO PERHAPS ADD THUNDER TO THE PRVAILING GROUP JUST PRIOR TO ISSUANCE TIME...IF IT CAN BE DONE WITH GOOD CONFIDENCE. MODELS AND SOME UPSTREAM OBSERVATIONS SUGGEST MVFR CONDITIONS AFTER 06Z. WITH SURFACE WINDS PICKING UP...MORE CONFIDENT ON STRATUS THAN FOG. WITH THE UPPER LOW IN THE VICINITY...COLD AIR ALOFT AND LINGERING LOW LEVEL MOISTURE...PLENTY OF DIURNAL MVFR CU WILL BE AROUND FRIDAY BEFORE CLEARING COMMENCES AT SUNSET AS HIGH PRESSURE BUILDS IN FROM THE MISSISSIPPI VALLEY. OTHERWISE...SOUTHWEST WINDS AT IND AND BMG SHOULD BECOME NORTHWEST AROUND 02Z WHEN THE FRONT MOVES THROUGH. WINDS WILL INCREASE TO NEAR 10 KNOTS TOWARD 12Z AND 10 TO 15 KNOTS AFTER 15Z. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PUMA NEAR TERM...PUMA SHORT TERM...PUMA LONG TERM....JAS AVIATION...MK
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
445 PM EDT THU AUG 9 2012 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 226 PM EDT THU AUG 9 2012 LOW PRESSURE OVER SOUTHEASTERN ILLINOIS WILL PUSH NORTHEAST TONIGHT...DRAGGING A COLD FRONT ACROSS CENTRAL INDIANA THIS EVENING. THIS IN COMBINATION WITH DAYTIME HEATING WILL ALLOW FOR SCATTERED THUNDERSTORMS TO DEVELOP LATE THIS AFTERNOON AND THIS EVENING ALONG AND AHEAD OF THE FRONT. THE LOW WILL SLOWLY PUSH TO THE EASTERN GREAT LAKES ON FRIDAY AND SATURDAY...ALLOWING COOLER AIR ON NORTHWEST WINDS AND DRY WEATHER TO ARRIVE IN CENTRAL INDIANA FOR THE WEEKEND. COOLER WEATHER IS EXPECTED MUCH OF NEXT WEEK. A LOW PRESSURE SYSTEM PASSING TO THE SOUTH ON WEDNESDAY AND A COLD FRONT APPROACHING ON THURSDAY NIGHT AND FRIDAY WILL BRING OUR NEXT CHANCES FOR SHOWERS AND STORMS. && .NEAR TERM /TONIGHT/... ISSUED AT 226 PM EDT THU AUG 9 2012 SURFACE ANALYSIS EARLY THIS AFTERNOON SHOWS LOW PRESSURE NEAR STL WITH A COLD FRONT EXTENDING SW INTO NW ARKANSAS AND A WARM FRONT STRETCHING SE ACROSS SOUTHERN ILLINOIS AND SOUTHERN INDIANA. VISIBLE PICTURE SHOW PLENTY OF CLOUD COVER ACROSS CENTRAL INDIANA...HOWEVER CLEARING WAS IN PLACE ACROSS CENTRAL AND SOUTHERN ILLINOIS. DEW POINT TEMPS REMAINED MOIST IN THE 60S. RADAR SHOWS TSRA DEVELOPING OVER CENTRAL KENTUCKY AND SW OHIO. MAIN FORECAST CHALLENGE WILL BE POPS. AS THE LOW PRESSURE SYSTEM NEAR STL IS EXPECTED TO TRACK NE TONIGHT MORE FAVORABLE CONDITIONS ARE EXPECTED OVER ILLINOIS FOR CONVECTION DEVELOPMENT. LIFTED INDICES REMAIN NEGATIVE THIS AFTERNOON AHEAD OF THE FRONT WITH FAVORABLE CAPE IN EXCESS OF 1300 J/KG. HRRR DEVELOPS BEST CONVECTION ALONG THE COLD FRONT WHICH SHOULD PASS ACROSS CENTRAL INDIANA AFTER 00Z. 0-3KM SHEAR AXIS OF NEAR 25-30 KNTS PUSH ACROSS THE STATE WITH ET FRONT AS WELL. THUS WILL KEEP TSRA MENTION WITH LIKELY OR BETTER POPS FOR TONIGHT. AS THE FRONT DEPARTS TOWARD 12Z FORECAST SOUNDINGS SHOW MUCH DRIER AIR ARRIVING. WILL TREND POPS DOWNWARD AFTER 06Z. AS FOR LOWS...WILL USE A BLEND OF MAVMOS AND METMOS GIVEN THE CHANGE IN AIRMASS. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... ISSUED AT 226 PM EDT THU AUG 9 2012 MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE OVERALL PATTERN AND WILL USE A BLEND. MAIN FORECAST CHALLENGE WILL BE TEMPS THROUGH THE PERIOD. NAM/GFS AGREE THAT A DEEP UPPER LOW EXPECTED TO BE OVER NORTHERN INDIANA ON FRIDAY WILL SLOWLY DRIFT NORTHEAST TO THE GREAT LAKES. ABUNDANT CLOUD COVER IS EXPECTED TO REMAIN ACROSS THE AREA ON FRIDAY AS THE LOW DRIFTS TO THE NORTH. TIME HEIGHT SECTIONS SHOW GOOD LOWER LEVEL MOISTURE. FURTHERMORE FORECAST SOUNDINGS SHOW CONVECTIVE TEMPERATURES IN THE LOWER 70S THAT COULD RESULT IN SOME ISOLATED POP UP AFTERNOON RAIN SHOWERS. WILL TREND HIGHS COOLER THAN MAVMOS GIVEN THE EXPECTED CLOUDS AND THE COLD AIR ADVECTION. LINGERING CLOUDS AND ANY ISOLATED SHRA WILL DISSIPATE ON FRIDAY NIGHT AS UPPER LOW PULLS NORTHEAST AND ANY DAYTIME HEATING WANES. EVEN BETTER DRYING APPEARS IN THE FORECAST SOUNDINGS IN ON FRIDAY NIGHT AND SATURDAY...CONTINUING INTO SATURDAY NIGHT AS HIGH PRESSURE REMAINS ACROSS THE AREA. GIVEN THE COLD AIR ADVECTION AS 850MB TEMPS FALL NEAR 10C WILL TREND HIGHS AND LOWS COOLER THAN MAVMOS...WITH MOSTLY CLEAR NIGHTS AND A SUNNY SATURDAY. SURFACE HIGH REMAINS IN CONTROL IN SUNDAY ACROSS THE OHIO VALLEY...HOWEVER ALOFT A SHORT WAVE IS APPROACHING AND PUSHING THROUGH INDIANA. SURFACE FLOW DOES NOT APPEAR TO OPEN AND ALLOW FOR THE ADDITION OF GULF MOISTURE. THUS FOR NOW WILL HOLD OFF ON POPS FOR SUNDAY UNTIL BETTER CONFIDENCE IS REVEALED IN LOWER LEVEL MOISTURE....BUT WILL INCREASE CLOUD COVERAGE. && .LONG TERM /MONDAY THROUGH THURSDAY/... ISSUED AT 226 PM EDT THU AUG 9 2012 ENSEMBLES SUGGEST A FAIRLY PROGRESSIVE FLOW ACROSS THE NORTHERN PARTS OF THE COUNTRY...WHILE THE SUB TROPICAL RIDGE HOLDS FROM THE SOUTHERN ROCKIES EASTWARD ACROSS THE GULF COAST STATES. ANOTHER UPPER DISTURBANCE IS EXPECTED TO DROP INTO THE GREAT LAKES AND OHIO VALLEY EARLY NEXT WEEK...AND THEN LIFT OFF TO THE EAST BY THE MIDDLE OF NEXT WEEK. ENSEMBLES SUGGEST THE BEST THREAT FOR PRECIPITATION WITH THIS SYSTEM WILL BE MONDAY AND MONDAY NIGHT. WILL GO WITH CHANCE POPS AT THOSE TIMES. HEIGHTS ARE EXPECTED TO RISE TOWARDS THE MIDDLE OF NEXT WEEK AS TROUGH LIFTS OFF TO THE EAST...SO WILL CONTINUE WITH A DRY FORECAST FOR TUESDAY AND WEDNESDAY. BY THURSDAY...THERE ARE INDICATIONS THAT THE HEAT RIDGE MAY TRY TO BUILD BACK INTO THE SOUTHERN PLAINS. THE ENSEMBLES SUGGEST ANOTHER DISTURBANCE MAY RIDE OVER THE DEVELOPING RIDGE INTO THE LOCAL AREA BY THURSDAY. WILL CONTINUE WITH CHANCE POPS AT THAT TIME. && .AVIATION /DISCUSSION FOR THE 092100Z TAF UPDATES/... ISSUED AT 445 PM EDT THU AUG 9 2012 THUNDERSTORMS ARE TAKING THEIR TIME DEVELOPING THIS AFTERNOON BUT WITH LITTLE TO NO CAP...SHOULD NOT TAKE LONG. FOR THE UPDATE...TOOK OUT UNNECESSARY HIGH LEVEL CEILINGS AND MADE MINOR TWEAKS TO WINDS. OTHERWISE...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS.... SOME LOW POTENTIAL FOR DISORGANIZED CONVECTION EXPECTED TO LINGER THROUGH THE MID AFTERNOON HOURS OVER THE TAF SITES AS WARM ADVECTION CONTINUES OVER A SURFACE BOUNDARY LOCATED SOUTH OF THE OHIO RIVER. MOST OF THE STRONGER INSTABILITY HAS BEEN SWEPT OUT OF THE LOCAL AREA DUE TO CONVECTION EARLY THIS MORNING...SO THERE IS SOME DOUBT ABOUT HOW MUCH CONVECTION MAY REDEVELOP LATER THIS AFTERNOON. APPEARS THE BEST CHANCES FOR CONVECTION WILL BE WITH A COLD FRONT...WHICH WILL DROP SOUTHEAST ACROSS THE TAF SITES ROUGHLY IN THE 092300Z-100400Z TIME FRAME. WILL CONCENTRATE THE THUNDER THREAT DURING THESE TIMES IN THE FORECAST. BRIEF IFR VISIBILITY RESTRICTIONS LIKELY IN THE HEAVIER CELLS. CONVECTIVE CLOUD BASES 030-040. OUTSIDE OF ANY CONVECTION...CEILINGS ABOVE 050/SURFACE WINDS BELOW 12 KTS EXPECTED FOR THE MOST PART THROUGH 100600Z. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PUMA NEAR TERM...PUMA SHORT TERM...PUMA LONG TERM....JAS AVIATION...JAS/MK
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
227 PM EDT THU AUG 9 2012 .UPDATE... THE SYNOPSIS...NEAR TERM...SHORT TERM AND LONG TERM SECTIONS HAVE BEEN UPDATED BELOW && .SYNOPSIS... ISSUED AT 226 PM EDT THU AUG 9 2012 LOW PRESSURE OVER SOUTHEASTERN ILLINOIS WILL PUSH NORTHEAST TONIGHT...DRAGGING A COLD FRONT ACROSS CENTRAL INDIANA THIS EVENING. THIS IN COMBINATION WITH DAYTIME HEATING WILL ALLOW FOR SCATTERED THUNDERSTORMS TO DEVELOP LATE THIS AFTERNOON AND THIS EVENING ALONG AND AHEAD OF THE FRONT. THE LOW WILL SLOWLY PUSH TO THE EASTERN GREAT LAKES ON FRIDAY AND SATURDAY...ALLOWING COOLER AIR ON NORTHWEST WINDS AND DRY WEATHER TO ARRIVE IN CENTRAL INDIANA FOR THE WEEKEND. COOLER WEATHER IS EXPECTED MUCH OF NEXT WEEK. A LOW PRESSURE SYSTEM PASSING TO THE SOUTH ON WEDNESDAY AND A COLD FRONT APPROACHING ON THURSDAY NIGHT AND FRIDAY WILL BRING OUR NEXT CHANCES FOR SHOWERS AND STORMS. && .NEAR TERM /TONIGHT/... ISSUED AT 226 PM EDT THU AUG 9 2012 SURFACE ANALYSIS EARLY THIS AFTERNOON SHOWS LOW PRESSURE NEAR STL WITH A COLD FRONT EXTENDING SW INTO NW ARKANSAS AND A WARM FRONT STRETCHING SE ACROSS SOUTHERN ILLINOIS AND SOUTHERN INDIANA. VISIBLE PICTURE SHOW PLENTY OF CLOUD COVER ACROSS CENTRAL INDIANA...HOWEVER CLEARING WAS IN PLACE ACROSS CENTRAL AND SOUTHERN ILLINOIS. DEW POINT TEMPS REMAINED MOIST IN THE 60S. RADAR SHOWS TSRA DEVELOPING OVER CENTRAL KENTUCKY AND SW OHIO. MAIN FORECAST CHALLENGE WILL BE POPS. AS THE LOW PRESSURE SYSTEM NEAR STL IS EXPECTED TO TRACK NE TONIGHT MORE FAVORABLE CONDITIONS ARE EXPECTED OVER ILLINOIS FOR CONVECTION DEVELOPMENT. LIFTED INDICES REMAIN NEGATIVE THIS AFTERNOON AHEAD OF THE FRONT WITH FAVORABLE CAPE IN EXCESS OF 1300 J/KG. HRRR DEVELOPS BEST CONVECTION ALONG THE COLD FRONT WHICH SHOULD PASS ACROSS CENTRAL INDIANA AFTER 00Z. 0-3KM SHEAR AXIS OF NEAR 25-30 KNTS PUSH ACROSS THE STATE WITH ET FRONT AS WELL. THUS WILL KEEP TSRA MENTION WITH LIKELY OR BETTER POPS FOR TONIGHT. AS THE FRONT DEPARTS TOWARD 12Z FORECAST SOUNDINGS SHOW MUCH DRIER AIR ARRIVING. WILL TREND POPS DOWNWARD AFTER 06Z. AS FOR LOWS...WILL USE A BLEND OF MAVMOS AND METMOS GIVEN THE CHANGE IN AIRMASS. && .SHORT TERM /FRIDAY THROUGH SUNDAY/... ISSUED AT 226 PM EDT THU AUG 9 2012 MODELS ARE IN PRETTY GOOD AGREEMENT WITH THE OVERALL PATTERN AND WILL USE A BLEND. MAIN FORECAST CHALLENGE WILL BE TEMPS THROUGH THE PERIOD. NAM/GFS AGREE THAT A DEEP UPPER LOW EXPECTED TO BE OVER NORTHERN INDIANA ON FRIDAY WILL SLOWLY DRIFT NORTHEAST TO THE GREAT LAKES. ABUNDANT CLOUD COVER IS EXPECTED TO REMAIN ACROSS THE AREA ON FRIDAY AS THE LOW DRIFTS TO THE NORTH. TIME HEIGHT SECTIONS SHOW GOOD LOWER LEVEL MOISTURE. FURTHERMORE FORECAST SOUNDINGS SHOW CONVECTIVE TEMPERATURES IN THE LOWER 70S THAT COULD RESULT IN SOME ISOLATED POP UP AFTERNOON RAIN SHOWERS. WILL TREND HIGHS COOLER THAN MAVMOS GIVEN THE EXPECTED CLOUDS AND THE COLD AIR ADVECTION. LINGERING CLOUDS AND ANY ISOLATED SHRA WILL DISSIPATE ON FRIDAY NIGHT AS UPPER LOW PULLS NORTHEAST AND ANY DAYTIME HEATING WANES. EVEN BETTER DRYING APPEARS IN THE FORECAST SOUNDINGS IN ON FRIDAY NIGHT AND SATURDAY...CONTINUING INTO SATURDAY NIGHT AS HIGH PRESSURE REMAINS ACROSS THE AREA. GIVEN THE COLD AIR ADVECTION AS 850MB TEMPS FALL NEAR 10C WILL TREND HIGHS AND LOWS COOLER THAN MAVMOS...WITH MOSTLY CLEAR NIGHTS AND A SUNNY SATURDAY. SURFACE HIGH REMAINS IN CONTROL IN SUNDAY ACROSS THE OHIO VALLEY...HOWEVER ALOFT A SHORT WAVE IS APPROACHING AND PUSHING THROUGH INDIANA. SURFACE FLOW DOES NOT APPEAR TO OPEN AND ALLOW FOR THE ADDITION OF GULF MOISTURE. THUS FOR NOW WILL HOLD OFF ON POPS FOR SUNDAY UNTIL BETTER CONFIDENCE IS REVEALED IN LOWER LEVEL MOISTURE....BUT WILL INCREASE CLOUD COVERAGE. && .LONG TERM /MONDAY THROUGH THURSDAY/... ISSUED AT 226 PM EDT THU AUG 9 2012 ENSEMBLES SUGGEST A FAIRLY PROGRESSIVE FLOW ACROSS THE NORTHERN PARTS OF THE COUNTRY...WHILE THE SUB TROPICAL RIDGE HOLDS FROM THE SOUTHERN ROCKIES EASTWARD ACROSS THE GULF COAST STATES. ANOTHER UPPER DISTURBANCE IS EXPECTED TO DROP INTO THE GREAT LAKES AND OHIO VALLEY EARLY NEXT WEEK...AND THEN LIFT OFF TO THE EAST BY THE MIDDLE OF NEXT WEEK. ENSEMBLES SUGGEST THE BEST THREAT FOR PRECIPITATION WITH THIS SYSTEM WILL BE MONDAY AND MONDAY NIGHT. WILL GO WITH CHANCE POPS AT THOSE TIMES. HEIGHTS ARE EXPECTED TO RISE TOWARDS THE MIDDLE OF NEXT WEEK AS TROUGH LIFTS OFF TO THE EAST...SO WILL CONTINUE WITH A DRY FORECAST FOR TUESDAY AND WEDNESDAY. BY THURSDAY...THERE ARE INDICATIONS THAT THE HEAT RIDGE MAY TRY TO BUILD BACK INTO THE SOUTHERN PLAINS. THE ENSEMBLES SUGGEST ANOTHER DISTURBANCE MAY RIDE OVER THE DEVELOPING RIDGE INTO THE LOCAL AREA BY THURSDAY. WILL CONTINUE WITH CHANCE POPS AT THAT TIME. && .AVIATION /DISCUSSION FOR THE 091800Z TAFS/... ISSUED AT 1235 PM EDT THU AUG 9 2012 SOME LOW POTENTIAL FOR DISORGANIZED CONVECTION EXPECTED TO LINGER THROUGH THE MID AFTERNOON HOURS OVER THE TAF SITES AS WARM ADVECTION CONTINUES OVER A SURFACE BOUNDARY LOCATED SOUTH OF THE OHIO RIVER. MOST OF THE STRONGER INSTABILITY HAS BEEN SWEPT OUT OF THE LOCAL AREA DUE TO CONVECTION EARLY THIS MORNING...SO THERE IS SOME DOUBT ABOUT HOW MUCH CONVECTION MAY REDEVELOP LATER THIS AFTERNOON. APPEARS THE BEST CHANCES FOR CONVECTION WILL BE WITH A COLD FRONT...WHICH WILL DROP SOUTHEAST ACROSS THE TAF SITES ROUGHLY IN THE 092300Z-100400Z TIME FRAME. WILL CONCENTRATE THE THUNDER THREAT DURING THESE TIMES IN THE FORECAST. BRIEF IFR VISIBILITY RESTRICTIONS LIKELY IN THE HEAVIER CELLS. CONVECTIVE CLOUD BASES 030-040. OUTSIDE OF ANY CONVECTION...CEILINGS ABOVE 050/SURFACE WINDS BELOW 12 KTS EXPECTED FOR THE MOST PART THROUGH 100600Z. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...PUMA NEAR TERM...PUMA SHORT TERM...PUMA LONG TERM....JAS AVIATION...JAS
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1238 AM EDT THU AUG 9 2012 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 246 PM EDT WED AUG 8 2012 A FRONTAL SYSTEM IS EXPECTED TO DROP SOUTH INTO THE AREA TONIGHT. A WAVE OF LOW PRESSURE WILL MOVE ACROSS NORTHERN INDIANA DURING THE DAY ON THURSDAY. THIS WILL DRAG A COLD FRONT THROUGH THE AREA THURSDAY AFTERNOON AND NIGHT. IN THE WAKE OF THIS FRONT...HIGH PRESSURE WILL BUILD INTO THE REGION. ANOTHER WEAK FRONTAL SYSTEM MAY AFFECT THE AREA LATE IN THE WEEKEND OR EARLY NEXT WEEK. && .NEAR TERM /TONIGHT/... ISSUED AT 920 PM EDT WED AUG 8 2012 FOR THE REMAINDER OF THE NIGHT...WITH QUASISTATIONARY BOUNDARY IN THE AREA...AND WEAK UPPER LEVEL WAVES...INCLUDING REMNANT MCV MOVING THROUGH SRN GREAT LAKES...EXPECT SCATTERED THUNDERSTORMS. COVERAGE HAS BEEN SLOW TO EXPAND THUS FAR THIS EVENING...ALTHOUGH THERE IS SOME HINT IN SREF PROBABILITIES...RAP...AND HRRR THAT EXPANSION OF COVERAGE MAY OCCUR WITH A SLIGHT INCREASE IN MID LEVEL FLOW LATE TONIGHT. CONSIDERING THIS...HAVE DEPICTED 40 TO 50 POPS WITH SCATTERED WORDING THROUGHOUT...AND POPS HIGHEST IN VICINITY OF THE BOUNDARY. ISOLATED STRONG STORM CANNOT BE RULED OUT...AND 5 PERCENT/SEE TEXT ON DAY ONE OUTLOOK PERFECTLY REASONABLE. INCREASED CLOUD COVER AND AS A RESULT...IN CONCERT WITH LATEST HOURLY NUMERICAL GUIDANCE AND OBSERVATIONAL TRENDS...BUMPED MIN TEMPS UP SLIGHTLY IN SOME PORTIONS OF THE AREA. STILL MID 60S TO AROUND 70...JUST SOME MINOR TWEAKS TO INDIVIDUAL NUMBERS. && .SHORT TERM /THURSDAY THROUGH SATURDAY/... ISSUED AT 246 PM EDT WED AUG 8 2012 MODELS INDICATE A COUPLE OF UPPER DISTURBANCES WILL AFFECT THE FORECAST AREA DURING THIS PERIOD. ONE WAVE...CURRENTLY OVER THE UPPER MISSISSIPPI VALLEY...IS EXPECTED TO MOVE THROUGH THURSDAY AFTERNOON AND EVENING. THIS WILL BE FOLLOWED BY AN UPPER LOW WHICH WILL SETTLE INTO THE GREAT LAKES BY FRIDAY AND SATURDAY. A SURFACE LOW ASSOCIATED WITH THE FIRST UPPER WAVE IS EXPECTED TO MOVE ACROSS NORTHERN INDIANA THURSDAY AFTERNOON...WHICH WILL DRAG A COLD FRONT THROUGH THE FORECAST AREA LATE THURSDAY AFTERNOON INTO THURSDAY NIGHT. THIS SETUP LOOKS TO PROVIDE THE BEST CHANCES FOR PRECIPITATION DURING THIS PERIOD. DEEP LAYER SHEAR IS INITIALLY RATHER WEAK...BUT GETS PROGRESSIVELY STRONGER TOWARDS THE LATE AFTERNOON AND EARLY EVENING HOURS ON THURSDAY. MID LEVEL LAPSE RATES ARE MARGINALLY FAVORABLE FOR SEVERE STORMS...SO THERE IS SOME POTENTIAL FOR STORM ORGANIZATION AND ATTENDANT THREAT FOR MAINLY WIND DAMAGE GIVEN THE INCREASING DEEP SHEAR. WILL CONTINUE TO MENTION POPS FOR THURSDAY AND THURSDAY NIGHT...WITH THE HIGHEST POPS AROUND FRONTAL PASSAGE...FROM MID AFTERNOON THURSDAY UNTIL ABOUT MIDNIGHT THURSDAY NIGHT. WILL KEEP A SMALL POP IN THE FORECAST FOR FRIDAY WITH THE UPPER LOW IN THE AREA. APPEARS BY SATURDAY...THE UPPER LOW WILL HAVE DRIFTED FAR ENOUGH OFF TO THE NORTHEAST TO KEEP THAT PERIOD DRY. PROGGED LOW LEVEL THICKNESSES SUGGEST THE GFS MOS HIGHS FOR THURSDAY ARE PROBABLY ABOUT 3-6 DEGREES TOO LOW. THE HIGHS ON FRIDAY LOOK BETTER...BUT MAY STILL BE A LITTLE COOL. GUIDANCE LOWS LOOK OK AT THIS POINT. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... ISSUED AT 246 PM EDT WED AUG 8 2012 MODELS HAVE LOW RAIN CHANCES AT TIMES...BUT CONSIDERING RECENT BIASES A TOTALLY DRY FORECAST BEST BET. EUROPEAN MOS AND MEX TEMPS CLOSE THROUGH PERIOD. FOR MINS...CONSALL MODEL WE INITIALIZED WITH IS ALSO CLOSE AND SEE NO REASON TO CHANGE. EVERYTHING AGREES GRADUAL WARMING THROUGH THE PERIOD. GIVEN RECENT BIASES IN WARMING SITUATIONS WILL GO A FEW DEGREES ABOVE EVEN RELATIVELY HOT CONSALL. && .AVIATION /DISCUSSION FOR 090600Z TAF ISSUANCE/... ISSUED AT 1238 AM EDT THU AUG 9 2012 WILL NEED TEMPO GROUPS AFTER 06Z AND PROB GROUPS THE REST OF THE PERIOD AS AN UPPER TROUGH ACROSS THE MISSISSIPPI VALLEY PROGRESSES EAST TOWARDS CENTRAL INDIANA...AND AN UPPER LOW MOVES TO NEAR LAKE MICHIGAN AFTER 00Z TONIGHT. MEANWHILE...A FRONTAL BOUNDARY ALONG WITH THUNDERSTORM OUTFLOW BOUNDARIES...DEEPER MOISTURE AND INSTABILITY WILL ALSO SERVE TO FOCUS THUNDERSTORMS ACROSS CENTRAL INDIANA THROUGH THE TAF PERIOD. CEILINGS SHOULD MOSTLY BE VFR AWAY FROM THUNDERSTORMS UNTIL AFTER 00Z WHEN LOW LEVEL MOISTURE INCREASES. COULD SEE SOME MVFR OR WORSE VISIBILITY AT TIMES IN THUNDERSTORMS OR BRIEFLY IN FOG OVERNIGHT. MEANWHILE...WINDS SHOULD BE LESS THAN 10 KNOTS EXCEPT IN STORMS OR NEAR OUTFLOW BOUNDARIES. WIND DIRECTION WILL ALSO BE PROBLEMATIC DEPENDING ON WHERE THE BOUNDARIES SET UP. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...JAS NEAR TERM...NIELD SHORT TERM...JAS LONG TERM....JK AVIATION...MK
AREA FORECAST DISCUSSION
NWS GOODLAND KS
543 PM MDT FRI AUG 10 2012 .UPDATE... ISSUED AT 539 PM MDT FRI AUG 10 2012 THUNDERSTORMS EARLY THIS EVENING HAVE BEEN CONFINED TO THE PALMER DIVIDE AREA AND FRONT RANGE...SO REMOVED MENTION FOR THE EVENING HOURS. HOWEVER...MODELS SHOW A ROBUST 40-50KT LOW LEVEL JET DEVELOPING OVER THE AREA AFTER 06Z WITH MODEST ELEVATED INSTABILITY OF A FEW HUNDRED J/KG. HRRR SIMULATED REFLECTIVITY AND QPF OUTPUT FROM THE NAM AND GFS SUPPORT ADDING A SLIGHT CHANCE MENTION FOR OVERNIGHT ELEVATED CONVECTION. HARD TO PIN DOWN ANY LOCATION SO JUST BROADBRUSHED ALL AREAS. THIS ACTIVITY...IF IT DEVELOPS...COULD LINGER INTO SATURDAY MORNING. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 231 PM MDT FRI AUG 10 2012 A WEATHER DISTURBANCE CURRENTLY PRODUCING A FEW THUNDERSTORMS IN SOUTHWEST COLORADO IS EXPECTED TO MOVE INTO THE SOUTHERN COLORADO HIGH COUNTRY AND ADJACENT PLAINS BY THE END OF TODAY THEN SOUTHEAST INTO SOUTHWEST KANSAS BY MIDNIGHT BEFORE CONTINUING SOUTHEAST SATURDAY MORNING. ANOTHER WEATHER SYSTEM AND ASSOCIATED SFC TROUGH WILL BRING ANOTHER SLIGHT CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE AREA SATURDAY AFTERNOON. PRECIPITATION CHANCES TONIGHT WILL BE CONFINED TO AREAS IN EASTERN COLORADO AND SOUTH OF INTERSTATE 70. OVERNIGHT LOWS IN THE UPPER 50S TO LOW 60S. HIGHS ON SATURDAY GENERALLY IN THE 90S. IT SHOULD BE NOTED THAT 850MB TEMPERATURES FROM THE NAM/UKMET SUPPORT READINGS CLOSER TO 100 DEGREES IN THE HILL CITY...MCCOOK AND TRIBUNE AREAS. THE GFS 850MB TEMPERATURES SUPPORT READINGS SEVERAL DEGREES COOLER. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 231 PM MDT FRI AUG 10 2012 MAIN FORECAST CONCERN WILL BE CHANCES FOR PRECIP. ACCOMPANYING THE COLD FRONT SATURDAY NIGHT. SATURDAY EVENING A COLD FRONT WILL BE OVER THE WESTERN THIRD TO HALF OF THE AREA. MODELS DISAGREE WITH THE TIMING OF THE FRONT THROUGH THE NIGHT AS WELL AS AVAILABLE MOISTURE TO WORK WITH. THE NAM/ECMWF HAVE THE FRONT EXITING THE AREA DURING THE LATE EVENING...WHILE THE GFS/SREF HAVE THE FRONT EXITING THE AREA BY EARLY SUNDAY MORNING. FAVORED MORE OF A GFS/SREF SOLUTION SINCE ALMOST ALL OF THE GEFS MEMBERS AGREED WITH THE GFS/SREF TIMING OF THE FRONT. MODELS HAVE MOST OF THE LIFT/INSTABILITY FOCUSED ALONG THE FRONT...SO AM THINKING THE MAJORITY OF THE PRECIPITATION ACTIVITY SHOULD REMAIN TIED TO THE FRONT. 850-700MB FRONTOGENESIS INCREASE DURING THE EVENING ALONG THE FRONT THEN DECLINE AS THE FRONT MOVES SOUTHEAST...SO TRENDED PRECIP. CHANCES UPWARD IN THE EVENING THEN LEVELED THEM OFF DURING THE OVERNIGHT HOURS. WITH 0-6KM SHEAR AROUND 30 KTS...AM THINKING ANY SEVERE WEATHER THREAT SHOULD BE CONFINED TO THE EVENING HOURS WHEN 700-500MB CAPE AND INSTABILITY FROM DAYTIME HEATING ARE BEST. SUNDAY WILL BE DRY AS HIGH PRESSURE BUILDS INTO THE AREA BEHIND THE COLD FRONT. AHEAD OF THE HIGH PRESSURE WINDS WILL BE GUSTY DURING THE DAY...MAINLY EAST OF A BENKELMAN TO GOVE LINE...WITH GUSTS UP TO 35 MPH POSSIBLE WHICH MAY CAUSE FIRE WEATHER CONCERNS. SEE FIRE WEATHER SECTION FOR MORE INFORMATION. THE GUSTS WILL DECLINE DURING THE EARLY EVENING AS MIXING DISSIPATES. DURING THE LATE AFTERNOON INTO THE EVENING MODELS SHOW SOME SURFACE CONVERGENCE OVER THE FAR SOUTHWEST PART OF THE AREA ON THE PERIPHERY OF THE SURFACE RIDGE. HOWEVER 500MB SUBSIDENCE IS ALSO PRESENT OVER THE SAME AREA SO WILL ONLY PLACE IN SILENT CHANCES AT THIS TIME. THE MONDAY THROUGH FRIDAY PERIOD STARTS OUT WITH HIT AND MISS PRECIPITATION CHANCES AS A FEW MINOR UPPER LEVEL DISTURBANCES MOVE OVER THE TRI-STATE AREA. PRECIPITATION CHANCES INCREASE AS AN UPPER LEVEL LONG WAVE TROUGH...THAT MOVES ON SHORE TUESDAY...PASSES OVER THE AREA WEDNESDAY NIGHT AND THURSDAY BRINGING A COLD FRONT WITH IT. PRECIPITATION CHANCES CONTINUE ON FRIDAY AS MINOR UPPER LEVEL DISTURBANCES IN THE FLOW MOVE OVER THE AREA. TEMPERATURES WILL BE NEAR NORMAL WITH HIGHS IN THE LOWER 90S AND LOWS IN THE LOWER/MID 60S AHEAD OF THE COLD FRONT...WITH HIGHS IN THE 80S AND LOWS IN THE MID 50S TO LOWER 60S BEHIND THE FRONT. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 520 PM MDT FRI AUG 10 2012 VFR CONDITIONS EXPECTED AT BOTH KGLD AND KMCK THROUGH THE TAF PERIOD. SOME UNCERTAINTY EXISTS VERY LATE IN THE PERIOD...SATURDAY NIGHT...WITH REGARDS TO FRONTAL TIMING AND CHANCE OF THUNDERSTORMS. ITS POSSIBLE THE FRONT COULD MAKE IT THROUGH KGLD AROUND 00Z WITH A WIND SHIFT TO THE NORTH AND SHORTLY AFTER AT KMCK...POSSIBLY ACCOMPANIED BY A BRIEF THUNDERSTORM. CONFIDENCE IS TOO LOW TO MENTION IN THE TAFS ATTM. && .FIRE WEATHER... ISSUED AT 231 PM MDT FRI AUG 10 2012 SUNDAY AFTERNOON WIND GUSTS UP TO 35 MPH MAY DEVELOP MAINLY IN THE MCCOOK TO HILL CITY AREA. RELATIVE HUMIDITIES WILL FALL TO AROUND 25 PERCENT. THESE CONDITIONS ARE ABOVE OUR FIRE WEATHER CRITERIA...SO AM NOT ANTICIPATING A HAZARD BEING NEEDED AT THIS TIME. HOWEVER THE GUSTY WINDS WILL MAKE ANY FIRE THAT IS BURNING DIFFICULT TO CONTROL. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...024 SHORT TERM...DDT LONG TERM...JTL AVIATION...024 FIRE WEATHER...JTL
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
734 PM EDT FRI AUG 10 2012 ...Updated Aviation Discussion... .Forecast Update... Issued at 445 PM EDT Fri Aug 10 2012 Updated the forecast to include 20-30% chance of rain showers over southern Indiana and north central Kentucky this evening. A line of showers moving south across Indiana was noted on radar early this evening, and it looks like the line will hold together into at least northern portions of the area. The 17Z HRRR depicts this line well and shows it dissipating around sunset with the lack of heating/instability. && .Short Term (Today through Saturday)... Issued at 307 PM EDT Fri Aug 10 2012 Surface cold has now cleared our forecast area. Cooler and somewhat drier air continues to mix in from the northwest. The colder air aloft has resulted in steep low-level lapse rates which is resulting in a fairly extensive area of stratocumulus. The stratocu should hang around for the next few hours and then begin to dissipate after sunset. Regional radars do show a few light showers/sprinkles to our north along the I-70 corridor. These will continue to move south and may clip a few of our northern Indiana counties this afternoon before they also dissipate after sunset. Temperatures will likely top off this afternoon in the upper 70s to the lower 80s and then slide off back into the 60s later this evening. For the overnight period, latest suite of model data continue to show plenty of cool air advection across the region. Model-time height cross sections show some low-level moisture lingering across the northeast sections of the forecast area. Probably will see a gradient clouds across the region with mostly clear skies across the west/southwest with partly cloudy skies across the northeast/Bluegrass. As for low temps, we`ll likely see temperatures fall into the mid-upper 50s in the north with upper 50s to the lower 60s in the south. We generally weighted temps closer to the weighted model consensus which has statistically done well. Saturday looks to be a pleasant day across the Ohio Valley with partly to mostly sunny skies as deep northwesterly flow continues across the region. Temperatures will be quite comfortable with highs in the upper 70s in the east with lower 80s in the central and western sections. Mostly clear skies are expected for Saturday Night with lows generally in the mid-upper 50s. .Long Term (Sunday through Friday)... Issued at 300 PM EDT Fri Aug 10 2012 A distinct pattern change will be fully in place by early this weekend. A broad longwave trough is forecast to lie over the upper midwest and the Great Lakes, with ridging pushed farther west across the Intermountain West. No excessive heat or bouts with high humidity are expected for basically the next week as rich Gulf moisture is forecast to remain across the southern states. On Sunday, the deep cyclone now over eastern Michigan is expected to slowly move northeast into Quebec. At the same time, another compact 500mb low will slide southeast across the Missouri Valley. Both the NAM and the GFS forecast weak low pressure to develop over Illinois Monday afternoon and move east across the Commonwealth overnight. Although this system will lack any robust moisture return, upper air divergence associated with the front exit region of the upper jet may provide enough upper air support for scattered thunderstorms during the late Monday through early Tuesday period. High temperatures will warm a bit from Sunday through Monday, with Monday`s highs in the mid to upper 80s expected to nearly match the climatological normal for mid-August. The ECMWF is nearly alone in its forecast of scattered showers on Wednesday. The preferred GFS depicts the Lower Ohio Valley within a a dry northerly flow on the backside of a departing system over western New England. Expect a cooldown once again beginning Tuesday afternoon, with mild temperatures continuing through Thursday. A deep cyclone forecast north of the upper midwest on Thursday will bring a cold front and a chance of storms for late Thursday and Friday. && .Aviation (00Z TAF issuance)... Issued at 730 PM EDT Fri Aug 10 2012 VFR conditions expected for this TAF period. A broken line of showers was noted near SDF at 23Z but should quickly move out with little effect on the terminal except some briefly gusty winds up to around 18 kts. Don`t think the line will survive much longer so have not included any VCSH at LEX although it`s still possible they could see a sprinkle. Breezy NNW winds should subside within the next hour or so. Overnight, it`s not out of the realm of possibilities for the TAF sites to see light fog or low cigs, but it`s becoming more unlikely. Strong dry air advection working in from the NW and mixy winds aloft should prohibit most fog formation. 18Z NAM Bufr soundings as well as NAM12 H925 RH indicate most low cigs should stay well to our north and east overnight. SDF/LEX would stand the best chance at any low clouds tonight. For tomorrow, expect only few-sct clouds around 4-6 kft during the afternoon/evening hours. Winds should remain out of the NWN maxing out between 6-8 kts tomorrow afternoon. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Update...........AMS Short Term.......MJ Long Term........JSD Aviation.........AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
331 PM EDT THU AUG 09 2012 .Short Term (Tonight through Friday Night)... Issued at 331 PM EDT Thu Aug 9 2012 ...Active Period of Weather Expected This Afternoon and Tonight... Fairly active period of weather is shaping up for the Ohio Valley this afternoon and tonight. In the near term, mid-level shortwave combined with surface temperatures hitting convective temperatures has resulted in convection firing across the region. Several areas of convection are occurring across the area. The first is an organizing line near the I-75 corridor in our eastern sections. This is being forced by the aforementioned mid-level wave and by diurnal heating. This activity will continue to head east and into WFO JKL`s area over the next hour or so. Further west, a well defined residual outflow boundary was located along our border with WFO IND. This boundary extends from northern Dubois county NE to Jefferson County. Convection is firing along this boundary due to strong moisture convergence and diurnal heating. This activity should head east-southeast over the next few hours. Finally additional convection is firing also over west KY. Based on the latest runs of the LMK WRF and 4km HRRR runs, this activity should also head east-southeast and may impact our far southwestern counties later this afternoon. Based on RUC proximity soundings, this afternoon`s convective activity is likely to remain in the pulse variety with damaging winds, torrential rains and intense CG lightning being the main threats. Latest deterministic and ensemble model runs seem to be showing some forecast convergence with the forecast for later this evening and overnight. First mid-level trough will scoot east this evening while a secondary and more potent mid-level trough dropping down into the Ohio Valley late tonight. As this wave drops south, surface cyclone near KSTL will shift northeast while associated surface cold drags behind. Strong mid-level height falls will result in widespread synoptic scale lift across the region late tonight. This combined with forcing along the front should result in a secondary line of convection developing to our northwest and slide southeast overnight. Despite this line moving through during an instability minimum, the upper level dynamics appear to be strong enough to support convection despite the meager instability. Current thinking is that a convective line will generate along the I-70 corridor and then drop southeast overnight. The line will likely be strong to possibly severe especially to our northwest. However, as the line heads southeast, it is possible that line may weaken a bit as it slides through KY. Convection should be pushing through southern Indiana in the 04-06Z time frame and then through KY in the 06-11Z time frame. Have gone ahead and bumped up PoPs for the overnight period. Lows will remain mild with temperatures falling into the lower-mid 60s in the northwest and mid-upper 60s elsewhere. For Friday, the main forecast change here is that a lot more cloud cover will be likely during the morning hours. Latest model time-height model cross sections show plenty of low-level moisture lingering behind the frontal boundary as it pushes through. Thus, mostly cloudy skies seem very likely in the morning followed by progressive clearing during the afternoon and into the evening hours. Highs tomorrow will be quite cool compared to what we`ve seen over the last few months. We should see readings in the upper 70s in the east with upper 70s to lower 80s in the central and west. Lows Friday night will be quite comfortable with lows in the mid-upper 50s. .Long Term (Saturday through Thursday)... Issued at 315 AM EDT Thu Aug 9 2012 ...Mostly Sunny, Dry, and Cool Weekend Ahead... A vertically stacked unseasonably far south and strong closed low will begin to slowly fill over Lake Huron Saturday. This system will slowly weaken and slowly lift north towards St. James Bay by late Sunday. In its wake, it will leave residual troughing across the western Great Lakes and the upper Midwest. By early Saturday, the occluded front related to this upper low will already have moved well east of the Commonwealth. Much drier and cooler air originating in Canada, will have overspread the state by dawn Saturday. Expect mostly clear skies and relatively cool temperatures for the upcoming weekend. Dewpoints will likely fall into the lower 50s by Saturday afternoon. Highs will struggle to exceed 80 on Saturday with highs on Sunday warming just a few degrees into the lower 80s. Overnight lows early Sunday will quite likely reach into the upper 50s, with perhaps our urban areas remaining near 60. A broad longwave trough will remain centered roughly over the Great Lakes during the early portion of next week. This will ensure no repeat of the excessively hot temperatures of early August anytime soon. Both the latest GFS and the ECMWF show a disturbance sliding southeast towards the base of this longwave trough Monday and Tuesday. This system will approach the Commonwealth by late Monday. At the surface, this system will likely aid in the formation of a weak surface trough that may serve as a focus for convection beginning late Monday, possibly continuing through the bulk of Tuesday. Will introduce a chance of storms for the later half of Monday, extending through Tuesday. Temperatures will warm a bit within the Monday through Thursday time period. However, even by Wednesday through Friday, temperatures will not exceed our seasonal mid-August averages with highs remaining in the upper 80s to around 90 && .Aviation (18Z TAF issuance)... Issued at 117 PM EDT Thu Aug 9 2012 Approaching mid-level wave combined with surface heating has led to the development of scattered convection in the I-65 corridor of central Kentucky. Activity appears to be developing along a residual northward moving outflow boundary. Expect scattered convection to continue developing across the region this afternoon. Initially, best coverage will be across north-central Kentucky, but as the area approaches the convective temperature, we should see convection gradually fill in. In general, VFR conditions are very likely outside any thunderstorms. If a storm impacts a terminal, a reduction in cigs and visibilities down to possibly tempo IFR will be possible. More organized convection is forecast to occur later this afternoon and evening as a secondary mid-level wave and associated surface cold front push through the region. These storms may pack a punch as they move through with torrential rainfall, gusty winds, and frequent lightning. Timing from the previous forecast still looks rather good with KBWG being impacted from 10/06-11Z, KSDF from 10/04-08Z and KLEX from about 10/08-12Z. Latest model progs show low-level moisture remaining in the region toward dawn with MVFR visibilities and near IFR/MVFR cigs. Low clouds will likely persist through the morning hours on Friday with improvement likely holding off until after 10/18Z. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...NONE. KY...NONE. $$ Short Term.......MJ Long Term........JSD Aviation.........MJ
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
949 PM CDT FRI AUG 10 2012 .UPDATE... WITH CONVECTION CONTINUING TO DECREASE OVER EAST CENTRAL LOUISIANA...WILL GO AHEAD AND CANCELLED THE REMAINDER OF THE SEVERE THUNDERSTORM WATCH. RUA && .PREV DISCUSSION... /ISSUED 921 PM CDT FRI AUG 10 2012/ UPDATE... HAVE CANCELLED THE SEVERE THUNDERSTORM WATCH FOR ALL EXCEPT PORTIONS OF EAST CENTRAL LOUISIANA...WHERE STILL SOME STRONG STORMS PERSIST. THE STORMS ARE ALSO ON THE DOWNWARD TREND WITH THE LOSS OF DAYTIME HEATING AND THE REAL GOOD INSTABILITY DECREASING. WILL LIKELY BE ABLE TO CANCEL THE REMAINDER OF THE WATCH BEFORE EXPIRATION TIME. ACTIVITY DEVELOPED AHEAD OF A SOUTHWARD MOVING BOUNDARY THAT DELINEATES...VERY MOIST MARITIME AIR TO THE SOUTH...WITH DRIER CONTINENTAL AIR TO THE NORTH. THIS BOUNDARY WILL CONTINUE A SLOW MOVEMENT TO THE SOUTH TONIGHT. COULD SEE SOME NOCTURNAL SHOWERS AND A FEW STORMS DEVELOP DURING THE LATE NIGHT AND BEFORE SUNRISE SOUTH OF THE BOUNDARY...MAINLY OVER LOWER ACADIANA...WHICH NAM AND RUC HINT AT. SO WILL KEEP CHANCE POPS GOING IN THAT AREA...AND TAPER THEM OFF TO SLIGHT CHANCE OR NONE...THE FURTHER WEST AND NORTH YOU GO. RUA PREV DISCUSSION... /ISSUED 711 PM CDT FRI AUG 10 2012/ UPDATE... A QUICK UPDATE TO REMOVE SOME OF OUR SE TX COUNTIES FM THE WATCH AND ADD A FEW FURTHER EAST IN LA. SCT STRONG TO SVR STORMS CONTINUE FROM NR BEAUMONT NE TOWARD ALEXANDRIA AND MARKSVILLE...WITH AN ESPECIALLY POTENT AND PROLIFIC LIGHTNING PRODUCING STORM JUST NE OF THE CWA DROPPING SWD TOWARD AVOYELLES PARISH. WILL CONTINUE TO MONITOR ACTIVITY...BUT ANTICIPATE MOST OF IT WILL BE DECREASING IN INTENSITY AND COVERAGE THE NEXT FEW HOURS. 24 PREV DISCUSSION... /ISSUED 617 PM CDT FRI AUG 10 2012/ DISCUSSION... 00Z TAF ISSUANCE. AVIATION... FRONTAL BOUNDARY OVER E TX/C LA IGNITING SCT/NUM TSRA JUST S OF THE BOUNDARY...WHICH WILL CONTINUE TO MOVE S THIS EVENING. INCREASED CHANCE OF TSRA EXPECTED FOR BPT/LCH BY 01-02Z...AND LFT/ARA BY 02-03Z THIS EVENING...WITH ACTIVITY LINGERING THRU 05-06Z. SVR WATCH 572 FOR SE TX/C AND SW LA THRU 05Z...NOT INCLUDING LFT/ARA. ACTIVITY EXPECTED TO DIMINISH BY 06Z...BUT NAM12 SHOWS REDEVELOPMENT TOWARDS 09-12Z ACROSS SC LA...WHICH WOULD AFFECT LFT/ARA DURING THIS TIME. WILL WAIT FOR 00Z RUN TO BITE ON THIS. DML PREV DISCUSSION... /ISSUED 501 PM CDT FRI AUG 10 2012/ SYNOPSIS... RUNNING A LITTLE LATE ON THE AFD THIS AFTN...BUT THAT TURNED OUT TO BE OK AS SEVERE THUNDERSTORM WATCH 572 WAS ISSUED AS I WAS PUTTING THIS TOGETHER EARLIER. ALREADY WENT AHEAD AND UPDATED ZONE AND COASTAL FORECASTS FOR THE WATCH. THE WATCH WAS PROMPTED BY A BAND OF STORMS THAT DEVELOPED QUICKLY THIS AFTN ALONG A PREFRONTAL TROF FM NATCHEZ TO JASPER TO CONROE. THESE STORMS RAPIDLY INTENSIFIED AS THEY ENTERED A VERY MOIST AND HEATED ATMOSPHERE ACRS SE TX AND WRN LA...AND ARE CAPABLE OF PRODUCING ABUNDANT CG LIGHTNING...GUSTY WINDS AND VERY HEAVY RAINFALL. OTHERWISE...THE LATEST UPPER AIR ANALYSES AND WV IMAGERY INDICATE THE AREA IS BETWEEN A TROF TO THE EAST AND A RIDGE OF HIGH PRESSURE ACRS THE SRN ROCKIES AND SW STATES. THIS IS PRODUCING A NLY FLOW ALOFT...WITH SEVERAL DISTURBANCES TRAVELING SOUTHWARD TOWARD THE REGION. ABUNDANT MOISTURE PERSISTS OVER THE AREA PER 12Z SOUNDINGS WITH PW VALUES AROUND 2 INCHES. AT THE SFC...A COLD FRONT WAS LOCATED FM GREENWOOD MS TO NR MONROE TO CENTERVILLE TX...SEPARATING DEWPOINTS IN THE MID 60S FM DEWPOINTS IN THE MID 70S. DISCUSSION... THINGS EXPECTED TO REMAIN ACTIVE FOR THROUGH EARLY EVENING AS STORMS CONTINUE TO FIRE ALONG THE AFOREMENTIONED TROF...WITH OUTFLOW BOUNDARY INTERACTIONS HELPING TO MAINTAIN ADDITIONAL DEVELOPMENT. ACTIVITY WILL TRAVEL SOUTHWARD...AND SHOULD DIMINISH BY MID-EVENING WITH THE LOSS OF DAYTIME HEATING...ALTHOUGH ANOTHER IMPULSE FURTHER UPSTREAM COULD BRING SOME MORE SCT ACTIVITY LATE TONIGHT. THE BIG QUESTION IS HOW FAR SOUTH WILL THE FRONT GET...AND VARIOUS MODEL GUIDANCE NOT IN TOTAL AGREEMENT ON HOW MANY OF US WILL SEE AT LEAST SOME RELIEF FM THE HUMIDITY. THE ECMWF AND NAM BOTH SHOW THE FRONT STALLING JUST NR OUR NRN CWA BORDER...WHILE THE CANADIAN...OPERATIONAL GFS AND GEM SHOW THE FRONT TREKKING FURTHER SOUTH INTO THE CWA...ESSENTIALLY STALLING IT CLOSER TO THE I-10 CORRIDOR. HPC GUIDANCE EARLIER TODAY LEANED TOWARD THE FORMER SOLUTIONS...BUT THE LATEST FCST SHOWS THE FRONT MOVING FURTHER SOUTH BEFORE STALLING. FOR THE GRIDS...CHOSE A BLEND OF GUIDANCE BUT WEIGHTED A LITTLE MORE ON THE NORTHERLY SOLUTIONS...WITH THE FRONT MAKING IT THROUGH AT LEAST THE NRN TIER OF COUNTIES/PARISHES. EXPECT SCT SHOWERS AND THUNDERSTORMS AGAIN SATURDAY...MAINLY ACRS SRN PORTIONS OF THE AREA WITH THE FRONT GRADUALLY WASHING OUT SATURDAY NIGHT INTO SUNDAY. RAIN CHANCES DIMINISH ON SUNDAY...WITH A RETURN TO A MORE TYPICAL SUMMERTIME PATTERN BY EARLY NEXT WEEK. HIGH PRESSURE WILL BECOME REESTABLISHED OVER THE NRN GULF AND GULF COAST STATES...WITH AFTN HIGHS IN THE 90S AND LOWS IN THE 70S. MARINE... HIGH PRESSURE RIDGING OVER THE NORTHERN GULF WILL MAINTAIN A LIGHT TO MODERATE SOUTHWESTERLY FLOW TONIGHT...WITH WINDS DIMINISHING OVER THE WEEKEND AS A WEAK FRONT STALLS ACROSS THE GULF COAST STATES. SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE MAINLY EAST OF SABINE PASS. A GENERALLY LIGHT ONSHORE FLOW...LOW SEAS AND MORE TYPICAL LATE NIGHT/EARLY MORNING SHOWERS WILL RESUME INTO THE COMING WEEK AS HIGH PRESSURE BECOMES REESTABLISHED OVER THE GULF COAST. 24 && .PRELIMINARY POINT TEMPS/POPS... KLCH 76 93 75 94 77 / 40 30 10 20 10 KBPT 76 93 74 94 77 / 40 20 10 20 10 KAEX 73 94 69 95 74 / 40 20 10 10 10 KLFT 76 92 74 95 76 / 40 30 10 20 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
921 PM CDT FRI AUG 10 2012 .UPDATE... HAVE CANCELLED THE SEVERE THUNDERSTORM WATCH FOR ALL EXCEPT PORTIONS OF EAST CENTRAL LOUISIANA...WHERE STILL SOME STRONG STORMS PERSIST. THE STORMS ARE ALSO ON THE DOWNWARD TREND WITH THE LOSS OF DAYTIME HEATING AND THE REAL GOOD INSTABILITY DECREASING. WILL LIKELY BE ABLE TO CANCEL THE REMAINDER OF THE WATCH BEFORE EXPIRATION TIME. ACTIVITY DEVELOPED AHEAD OF A SOUTHWARD MOVING BOUNDARY THAT DELINEATES...VERY MOIST MARITIME AIR TO THE SOUTH...WITH DRIER CONTINENTAL AIR TO THE NORTH. THIS BOUNDARY WILL CONTINUE A SLOW MOVEMENT TO THE SOUTH TONIGHT. COULD SEE SOME NOCTURNAL SHOWERS AND A FEW STORMS DEVELOP DURING THE LATE NIGHT AND BEFORE SUNRISE SOUTH OF THE BOUNDARY...MAINLY OVER LOWER ACADIANA...WHICH NAM AND RUC HINT AT. SO WILL KEEP CHANCE POPS GOING IN THAT AREA...AND TAPER THEM OFF TO SLIGHT CHANCE OR NONE...THE FURTHER WEST AND NORTH YOU GO. RUA && .PREV DISCUSSION... /ISSUED 711 PM CDT FRI AUG 10 2012/ UPDATE... A QUICK UPDATE TO REMOVE SOME OF OUR SE TX COUNTIES FM THE WATCH AND ADD A FEW FURTHER EAST IN LA. SCT STRONG TO SVR STORMS CONTINUE FROM NR BEAUMONT NE TOWARD ALEXANDRIA AND MARKSVILLE...WITH AN ESPECIALLY POTENT AND PROLIFIC LIGHTNING PRODUCING STORM JUST NE OF THE CWA DROPPING SWD TOWARD AVOYELLES PARISH. WILL CONTINUE TO MONITOR ACTIVITY...BUT ANTICIPATE MOST OF IT WILL BE DECREASING IN INTENSITY AND COVERAGE THE NEXT FEW HOURS. 24 PREV DISCUSSION... /ISSUED 617 PM CDT FRI AUG 10 2012/ DISCUSSION... 00Z TAF ISSUANCE. AVIATION... FRONTAL BOUNDARY OVER E TX/C LA IGNITING SCT/NUM TSRA JUST S OF THE BOUNDARY...WHICH WILL CONTINUE TO MOVE S THIS EVENING. INCREASED CHANCE OF TSRA EXPECTED FOR BPT/LCH BY 01-02Z...AND LFT/ARA BY 02-03Z THIS EVENING...WITH ACTIVITY LINGERING THRU 05-06Z. SVR WATCH 572 FOR SE TX/C AND SW LA THRU 05Z...NOT INCLUDING LFT/ARA. ACTIVITY EXPECTED TO DIMINISH BY 06Z...BUT NAM12 SHOWS REDEVELOPMENT TOWARDS 09-12Z ACROSS SC LA...WHICH WOULD AFFECT LFT/ARA DURING THIS TIME. WILL WAIT FOR 00Z RUN TO BITE ON THIS. DML PREV DISCUSSION... /ISSUED 501 PM CDT FRI AUG 10 2012/ SYNOPSIS... RUNNING A LITTLE LATE ON THE AFD THIS AFTN...BUT THAT TURNED OUT TO BE OK AS SEVERE THUNDERSTORM WATCH 572 WAS ISSUED AS I WAS PUTTING THIS TOGETHER EARLIER. ALREADY WENT AHEAD AND UPDATED ZONE AND COASTAL FORECASTS FOR THE WATCH. THE WATCH WAS PROMPTED BY A BAND OF STORMS THAT DEVELOPED QUICKLY THIS AFTN ALONG A PREFRONTAL TROF FM NATCHEZ TO JASPER TO CONROE. THESE STORMS RAPIDLY INTENSIFIED AS THEY ENTERED A VERY MOIST AND HEATED ATMOSPHERE ACRS SE TX AND WRN LA...AND ARE CAPABLE OF PRODUCING ABUNDANT CG LIGHTNING...GUSTY WINDS AND VERY HEAVY RAINFALL. OTHERWISE...THE LATEST UPPER AIR ANALYSES AND WV IMAGERY INDICATE THE AREA IS BETWEEN A TROF TO THE EAST AND A RIDGE OF HIGH PRESSURE ACRS THE SRN ROCKIES AND SW STATES. THIS IS PRODUCING A NLY FLOW ALOFT...WITH SEVERAL DISTURBANCES TRAVELING SOUTHWARD TOWARD THE REGION. ABUNDANT MOISTURE PERSISTS OVER THE AREA PER 12Z SOUNDINGS WITH PW VALUES AROUND 2 INCHES. AT THE SFC...A COLD FRONT WAS LOCATED FM GREENWOOD MS TO NR MONROE TO CENTERVILLE TX...SEPARATING DEWPOINTS IN THE MID 60S FM DEWPOINTS IN THE MID 70S. DISCUSSION... THINGS EXPECTED TO REMAIN ACTIVE FOR THROUGH EARLY EVENING AS STORMS CONTINUE TO FIRE ALONG THE AFOREMENTIONED TROF...WITH OUTFLOW BOUNDARY INTERACTIONS HELPING TO MAINTAIN ADDITIONAL DEVELOPMENT. ACTIVITY WILL TRAVEL SOUTHWARD...AND SHOULD DIMINISH BY MID-EVENING WITH THE LOSS OF DAYTIME HEATING...ALTHOUGH ANOTHER IMPULSE FURTHER UPSTREAM COULD BRING SOME MORE SCT ACTIVITY LATE TONIGHT. THE BIG QUESTION IS HOW FAR SOUTH WILL THE FRONT GET...AND VARIOUS MODEL GUIDANCE NOT IN TOTAL AGREEMENT ON HOW MANY OF US WILL SEE AT LEAST SOME RELIEF FM THE HUMIDITY. THE ECMWF AND NAM BOTH SHOW THE FRONT STALLING JUST NR OUR NRN CWA BORDER...WHILE THE CANADIAN...OPERATIONAL GFS AND GEM SHOW THE FRONT TREKKING FURTHER SOUTH INTO THE CWA...ESSENTIALLY STALLING IT CLOSER TO THE I-10 CORRIDOR. HPC GUIDANCE EARLIER TODAY LEANED TOWARD THE FORMER SOLUTIONS...BUT THE LATEST FCST SHOWS THE FRONT MOVING FURTHER SOUTH BEFORE STALLING. FOR THE GRIDS...CHOSE A BLEND OF GUIDANCE BUT WEIGHTED A LITTLE MORE ON THE NORTHERLY SOLUTIONS...WITH THE FRONT MAKING IT THROUGH AT LEAST THE NRN TIER OF COUNTIES/PARISHES. EXPECT SCT SHOWERS AND THUNDERSTORMS AGAIN SATURDAY...MAINLY ACRS SRN PORTIONS OF THE AREA WITH THE FRONT GRADUALLY WASHING OUT SATURDAY NIGHT INTO SUNDAY. RAIN CHANCES DIMINISH ON SUNDAY...WITH A RETURN TO A MORE TYPICAL SUMMERTIME PATTERN BY EARLY NEXT WEEK. HIGH PRESSURE WILL BECOME REESTABLISHED OVER THE NRN GULF AND GULF COAST STATES...WITH AFTN HIGHS IN THE 90S AND LOWS IN THE 70S. MARINE... HIGH PRESSURE RIDGING OVER THE NORTHERN GULF WILL MAINTAIN A LIGHT TO MODERATE SOUTHWESTERLY FLOW TONIGHT...WITH WINDS DIMINISHING OVER THE WEEKEND AS A WEAK FRONT STALLS ACROSS THE GULF COAST STATES. SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE MAINLY EAST OF SABINE PASS. A GENERALLY LIGHT ONSHORE FLOW...LOW SEAS AND MORE TYPICAL LATE NIGHT/EARLY MORNING SHOWERS WILL RESUME INTO THE COMING WEEK AS HIGH PRESSURE BECOMES REESTABLISHED OVER THE GULF COAST. 24 && .PRELIMINARY POINT TEMPS/POPS... KLCH 76 93 75 94 77 / 40 30 10 20 10 KBPT 76 93 74 94 77 / 40 20 10 20 10 KAEX 73 94 69 95 74 / 40 20 10 10 10 KLFT 76 92 74 95 76 / 40 30 10 20 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1046 AM EDT THU AUG 9 2012 .SYNOPSIS... A STALLED FRONT WILL BE THE FOCUS FOR SHOWERS AND STORMS TODAY. A MUCH LARGER SYSTEM WILL CONTINUE THE THREAT FOR ACTIVITY ON FRIDAY AND SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... STILL AT ODDS DETERMINING WHAT WILL HAPPEN WITH PRECIPITATION AND SEVERE POSSIBILITIES FOR TODAY. A COUPLE OF STORMS ARE CURRENTLY PASSING THROUGH EASTERN OHIO AND NORTHERN PENNSYLVANIA...BUT DIFFICULTY WILL LIE IN WHERE PRECIPITATION WILL OCCUR DURING THE AFTERNOON. HARD TO SAY WHETHER CONVECTION WILL REMAIN SCATTERED AND MULTICELLED...SIMILAR TO THE 00Z NCEP WRF NMM/ARW...OR WHETHER A LINE WILL DEVELOP IN OHIO AND MOVE TO THE EAST...AS SHOWN IN SEVERAL HRRR RUNS AND THE 12Z NAM. IN EITHER SCENARIO...WITH HIGHEST SHEAR VALUES EXPECTED TO REMAIN FARTHER NORTH ACROSS EXTREME NORTHEASTERN OHIO...EXTREME NORTHWESTERN PENNSYLVANIA...AND WESTERN NEW YORK...THIS MAY LIMIT SEVERE POSSIBILITIES. OF COURSE...SKIES REMAINING CLEAR SOUTH AND EAST OF PITTSBURGH WILL INCREASE INSTABILITY VALUES IN THAT AREA...EVEN IF SHEAR VALUES REMAIN LOW. WITH BEST SHEAR TO THE NORTH AND BEST INSTABILITY TO THE SOUTH...MAY JUST END UP WITH NON-SEVERE THUNDERSTORMS. LOW CONFIDENCE FORECAST FOR THIS AFTERNOON. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... AN LARGE UL LOW WILL MOVER OVER LOWER MI TONIGHT. THIS SYSTEM WILL DEVELOP A SFC LOW ALONG THE BOUNDARY AND FORCE THE BOUNDARY BACK NORTHWARD TONIGHT. THE TRAILING COLD FRONT WILL MOVE INTO W OHIO LATE TONIGHT AS THE 50 LOW DEEPENS AND MOVES SLOWLY EASTWARD. EXPECT TO SEE A BREAK IN THE ACTIVITY THIS EVENING, AS THE SFC AND UL LOW WILL BECOME THE FOCAL POINT AND THE UPPER OHIO VALLEY WILL BE IN THE WARM SECTOR. AS THE ENTIRE SYSTEM MOVES EASTWARD, EXPECT MORE SHOWERS AND STORMS TO BEGIN TO MOVE BACK INTO THE AREA LATE TONIGHT. THE SYSTEM WILL OCCLUDE FRIDAY MORNING AND SLOWLY MOVE EASTWARD. THE SFC FRONT WILL SPIN THROUGH FRIDAY AFTERNOON. EXPECT A WET FRIDAY WITH BELOW NORMAL TEMPS. ENTIRE SYSTEM WILL MOVE TOWARD THE NORTHERN GREAT LAKES ON SATURDAY. MOISTURE AND UL WAVES WILL ROTATE AROUND THE EXITING SYSTEM, KEEPING IN CLOUDS, COOL TEMPS AND THE RISK FOR SHOWERS THROUGH SAT. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... WRAPAROUND PRECIPITATION SHOULD BE SHIFTING TO THE NORTH BY SATURDAY EVE. HIGH PRESSURE WILL BUILD IN ON SUNDAY AND MOVE THROUGH ON MONDAY. LATEST GFS CONTINUES TO SHOW A WEAK SYSTEM MOVING THROUGH BY THE MIDDLE OF NEXT WEEK. WILL INCLUDE THE MENTION OF PRECIP AT THIS TIME. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... UPSTREAM CONVECTION AHEAD OF ANOTHER SHORT WAVE IN WESTERN OHIO IS LIKELY TO FALL APART BEFORE REACHING THE TERMINALS...LEAVING A TREMENDOUS AMOUNT OF MID-LEVEL CONVECTIVE DEBRIS CLOUD OVER MUCH OF THE AREA THROUGH AT LEAST THE EARLY AFTERNOON. AS SUCH...PREVIOUS PROB30S FOR THUNDER THIS AFTERNOON WERE NOT UPGRADED OR ENHANCED AS THUNDERSTORM DEVELOPMENT CHANCES SEEM TO BE LOWER THAN PREVIOUSLY ANTICIPATED. FRIES .OUTLOOK...FRIDAY THROUGH MONDAY... RESTRICTIONS CAN BE EXPECTED IN WIDESPREAD SHOWERS AND THUNDERSTORMS FRIDAY INTO FRIDAY NIGHT...WITH MORE ISOLATED COVERAGE EXPECTED SATURDAY AND SATURDAY NIGHT. SUNDAY AND MONDAY SHOULD SEE A RETURN TO VFR CONDITIONS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS BALTIMORE MD/WASHINGTON DC
1026 AM EDT THU AUG 9 2012 .SYNOPSIS... A COLD FRONT WILL APPROACH THE AREA FROM THE OHIO VALLEY TODAY...WITH A WEAK UPPER TROUGH MOVING ACROSS THE AREA THIS AFTERNOON. THE FRONT WILL SLOWLY CROSS THE REGION LATE FRIDAY INTO SATURDAY. HIGH PRESSURE WILL SETTLE ACROSS THE REGION SUNDAY THROUGH MONDAY...BEFORE ANOTHER COLD FRONT AFFECTS THE REGION THROUGH THE MIDDLE PART OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... ATMOSPHERIC DESTABILIZATION IS UNDERWAY WITH MOST LOCALES BREAKING OUT OF THE FOG/LOW CLOUDS FROM EARLIER THIS MORNING. CLUSTER OF SHOWERS AND THUNDERSTORMS THAT DEVELOPED OVER NORTHERN MARYLAND HAS EXPANDED AND WILL MOVE EAST ACROSS NORTHERN VIRGINIA. ADDITIONAL SHOWER AND THUNDERSTORM ACTIVITY CAN BE EXPECTED THIS AFTERNOON AS DAYTIME HEATING COMBINES WITH DECENT MOISTURE AND AN APPROACHING TROUGH. THERE REMAINS A THREAT FOR STRONG TO SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING WITH HIGH CAPE ENVT BUT SHEAR REMAINS WEAK. STORM MOTION WILL BE SLOW WITH HEAVY DOWNPOURS AND LOCALIZED FLOODING A CONCERN. NEAR-TERM MODELS ARE ALSO COLLECTIVELY KEYING-IN ON BASICALLY ONE LINE OR BROKEN LINE OF CONVECTION THAT MOVES ACROSS THE AREA OVER THE COURSE OF THE AFTN/EARLY EVE...W/ VERY LITTLE IMMEDIATELY BEHIND IT - THOUGH THE HRRR DOES CONTINUALLY DEVELOP CELLS BACK INTO WV MOST OF THE DAY. THIS SOLUTION DOES LINE-UP W/ THE FORECAST FOR A LEE TROUGH TO MOVE ACROSS THE AREA THIS AFTN...THE PRECURSOR TO THE INCOMING LOW PRESSURE SYSTEM ON FRIDAY - THESE FEATURES WILL AFFECT THE AREA ABOUT A DAY APART. THERE WILL BE ENOUGH LIFT BEHIND THE INITIAL LEE TROUGH PASSAGE AND THE INCOMING LOW PRESSURE SYSTEM TO DEVELOP SCATTERED BATCHES OF SHOWER ACTIVITY WELL INTO THE OVERNIGHT HRS. IT WILL STILL BE WARM TONIGHT - EVEN W/ OVERCAST SKIES AND SCATTERED SHOWERS SINCE THE HUMIDITY LEVELS WILL STAY FAIRLY HIGH. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... UPPER LEVEL LOW PRESSURE PROGRESSES INTO THE GREAT LAKES AREA BY EARLY FRIDAY. A DEEP SOUTHERLY FLOW REMAINS IN PLACE EARLY FRIDAY AS THE COLD FRONT CROSSES THE CENTRAL APPALACHIANS. THE GFS IS A LITTLE FASTER WITH THE TIMING OF THE FRONT THROUGH THE DC AREA...WHILE THE NAM REMAINS CONSISTENT BRINGING IT IN FRIDAY EVENING. THERE WILL BE DECENT MID LEVEL FRONTOGENESIS BACK OUT TOWARD W VA AHEAD OF THE UPPER TROF. SPC KEEPS US IN A SLIGHT RISK FOR SEVERE STORMS FRIDAY GIVEN UNCERTAINTY IN CLOUD COVER AND MARGINAL SHEAR. A PERIOD OF LOCALLY HEAVY RAINFALL IS LIKELY FRIDAY AFTERNOON AND EVENING WITH ISOLATED STRONG TO SEVERE THUNDERSTORMS. TEMPERATURES IN THE MID 80S ARE EXPECTED IN THE METRO AREAS WITH MUGGY DEW POINTS NEAR 70 DEGREES. BEHIND THE FRONT A DRIER NORTHWEST FLOW DEVELOPS. BOTH THE NAM AND GFS HAVE THE PRECIPITATION BAND PUSHING EAST OF OUR AREA BY 18Z SATURDAY. WE ARE CARRYING CHANCES OF SHOWERS ABOUT 6 HOURS BEHIND THIS TO ACCOUNT FOR THE POSSIBILITY OF EARLIER MODEL RUNS THAT THE FRONT WOULD HANG UP ACROSS OUR AREA...CERTAINLY POSSIBLE THIS TIME OF YEAR. COOLER TEMPERATURES ARE LIKELY SATURDAY IN EITHER EVENT. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... THE GFS AND ECMWF BRING A TROF INTO THE INLAND PACIFIC NORTHWEST BY THE END OF THIS PERIOD WITH A RIDGE REPLACING THE TROF CURRENTLY OVER MINNESOTA. THIS TELECONNECTS TO A WEAKER TROF OVER THE EASTERN U.S. AS THE OLD GREAT LAKES TROF EJECTS INTO EASTERN CANADA. SUNDAY LOOKS LIKE A NICE DAY WITH TEMPERATURES IN THE MID 80/S AND DEW POINTS IN THE 60/S. THE HUMIDITY BEGINS TO RETURN MONDAY AND TUESDAY WITH THE APPROACH OF THE NEXT UPSTREAM TROF AND AN INCREASING SOUTHERLY FLOW. TEMPERATURES RISE BACK INTO THE LOWER 90S BY MONDAY WITH A CHANCE OF THUNDERSTORMS OVER THE MOUNTAINS. THIS THREAT SPREADS INTO THE METRO AREAS TUESDAY AND WEDNESDAY. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... MOST OF THE FOG HAS MIXED OUT. SCATTERED SHOWERS AND THUNDERSTORMS WILL PERSIST THROUGH EARLY EVENING WITH OCCASIONAL REDUCTIONS IN VSBY AND CIGS TO MVFR. SOME OF THE STORMS COULD CONTAIN STRONG GUSTY WINDS AOA 40 KTS...SMALL HAIL AND HEAVY DOWNPOURS. PATCHY FOG WILL REDEVELOP OVERNIGHT INTO EARLY FRIDAY. POTENTIALLY SEVERE THUNDERSTORMS PROGRESS NORTHEAST THROUGH THE MID ATLANTIC FRIDAY WITH HEAVY RAIN AND POSSIBLE STRONG WINDS. THE COLD FRONT STALLS OVER CHESAPEAKE BAY REGION SATURDAY...WITH HIGH PRESSURE AND MAINLY VFR CONDITIONS EXPECTED SUNDAY AND MONDAY. && .MARINE... SLY WINDS WILL BEGIN TO CHANNEL AND STRENGTHEN LATER THIS AFTN. A SCA REMAINS IN EFFECT FOR THE BAY - MAINLY THE MAIN CHANNEL. THE PEAK WILL BE THIS EVENING AND INTO THE LATE NIGHT HRS...THEN GRADUALLY SUBSIDE FROM NORTH- TO-SOUTH. SHOWERS AND TSTMS ARE ALSO EXPECTED TO DEVELOP OFF THE WEST LATER THIS AFTN AND APPROACH THE WATERS...CREATING GUSTY WINDS IN LOCALIZED AREAS. SOUTHERLY CHANNELING WILL DEVELOP FRIDAY WITH WIND SPEEDS APPROACHING 15 KTS. WINDS WILL BECOME LOCALLY GUSTY OVER THE WATERS IN THUNDERSTORMS FRIDAY WITH REDUCED VISIBILITIES IN HEAVY DOWNPOURS. A SMALL CRAFT ADVISORY MAY BE NEEDED FRIDAY WITH GUSTY WINDS FROM THUNDERSTORMS INTO FRIDAY NIGHT. FRONT STALLS WITH CONTINUED SHOWERS AND THUNDERSTORMS SATURDAY. HIGH PRESSURE AND FAIR WEATHER IS EXPECTED SUNDAY AND MONDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 10 PM EDT THIS EVENING FOR ANZ530>533-537>542. SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 6 AM EDT FRIDAY FOR ANZ534-543. && $$ SYNOPSIS...GMS NEAR TERM...KRW SHORT TERM...GMS LONG TERM...SDG AVIATION...KRW/GMS MARINE...KRW/GMS
AREA FORECAST DISCUSSION...UPDATED
NWS BALTIMORE MD/WASHINGTON DC
746 AM EDT THU AUG 9 2012 .SYNOPSIS... A COLD FRONT WILL APPROACH THE AREA FROM THE OHIO VALLEY TODAY...WITH A WEAK UPPER TROUGH MOVING ACROSS THE AREA THIS AFTERNOON. THE FRONT WILL SLOWLY CROSS THE REGION LATE FRIDAY INTO SATURDAY. HIGH PRESSURE WILL SETTLE ACROSS THE REGION SUNDAY THROUGH MONDAY...BEFORE ANOTHER COLD FRONT AFFECTS THE REGION THROUGH THE MIDDLE PART OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... SCATTERED SHOWERS HAVE BEGUN TO TAKE SHAPE OVER NORTHERN MARYLAND...PARTICULARLY ALLEGANY AND WASHINGTON COUNTIES. EXPECT COVERAGE TO INCREASE ONCE THE FOG/HAZE/LOW CLOUDS MIX OUT AND DESTABILIZATION BEGINS TO OCCUR. A MOIST ATMOSPHERE COMBINED WITH HEATING AND AN APPROACHING TROUGH ALL POINT TO AN UPTICK IN CONVECTIVE ACTIVITY TODAY. MADE ADJUSTMENTS TO INCREASE POPS/INCREASE SKY GRIDS AND TO ADD MORE COVERAGE OF FOG EARLY THIS MORNING. WILL ALSO FURTHER INVESTIGATE HIGH TEMPERATURES THIS AFTERNOON GIVEN INCREASING CLOUDS APPROACHING FROM THE WEST. LOCAL HI-RES GUIDANCE DEVELOPS SCATTERED TSTMS ALONG THE HIGHER TERRAIN AND MOVES THEM EWD UNDER THE MOST PRONOUNCED MID-LEVEL STEERING FLOW WE`VE SEEN IN THE PAST FEW DAYS. THESE NEAR-TERM MODELS ARE ALSO COLLECTIVELY KEYING-IN ON BASICALLY ONE LINE OR BROKEN LINE OF CONVECTION THAT MOVES ACROSS THE AREA OVER THE COURSE OF THE AFTN/EARLY EVE...W/ VERY LITTLE IMMEDIATELY BEHIND IT - THOUGH THE HRRR DOES CONTINUALLY DEVELOP CELLS BACK INTO WV MOST OF THE DAY. THIS SOLUTION DOES LINE-UP W/ THE FORECAST FOR A LEE TROUGH TO MOVE ACROSS THE AREA THIS AFTN...THE PRECURSOR TO THE INCOMING LOW PRESSURE SYSTEM ON FRIDAY - THESE FEATURES WILL AFFECT THE AREA ABOUT A DAY APART. MODEST INSTABILITY WILL ALLOW FOR MORE ISOLATED/SCATTERED TSTMS W/ LOCALIZED HEAVY RAIN...GUSTY WINDS AND HAIL. ASSUMING THE EARLIER TSTM ACTIVITY CUTS DOWN ON THE INSTABILITY THIS AFTN W/ LITTLE RECOVERY TIME TILL THE OVERNIGHT HRS...CONVECTIVE CHANCES WILL DROP OFF TO A MORE ISOLATED/EMBEDDED NATURE FOR ANY OVERNIGHT PRECIP ACTIVITY. THERE WILL BE ENOUGH LIFT BEHIND THE INITIAL LEE TROUGH PASSAGE AND THE INCOMING LOW PRESSURE SYSTEM TO DEVELOP SCATTERED BATCHES OF SHOWER ACTIVITY WELL INTO THE OVERNIGHT HRS. IT WILL STILL BE WARM TONIGHT - EVEN W/ OVERCAST SKIES AND SCATTERED SHOWERS SINCE THE HUMIDITY LEVELS WILL STAY FAIRLY HIGH. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... UPPER LEVEL LOW PRESSURE PROGRESSES INTO THE GREAT LAKES AREA BY EARLY FRIDAY. A DEEP SOUTHERLY FLOW REMAINS IN PLACE EARLY FRIDAY AS THE COLD FRONT CROSSES THE CENTRAL APPALACHIANS. THE GFS IS A LITTLE FASTER WITH THE TIMING OF THE FRONT THROUGH THE DC AREA...WHILE THE NAM REMAINS CONSISTENT BRINGING IT IN FRIDAY EVENING. THERE WILL BE DECENT MID LEVEL FRONTOGENESIS BACK OUT TOWARD W VA AHEAD OF THE UPPER TROF. SPC KEEPS US IN A SLIGHT RISK FOR SEVERE STORMS FRIDAY GIVEN UNCERTAINTY IN CLOUD COVER AND MARGINAL SHEAR. A PERIOD OF LOCALLY HEAVY RAINFALL IS LIKELY FRIDAY AFTERNOON AND EVENING WITH ISOLATED STRONG TO SEVERE THUNDERSTORMS. TEMPERATURES IN THE MID 80S ARE EXPECTED IN THE METRO AREAS WITH MUGGY DEW POINTS NEAR 70 DEGREES. BEHIND THE FRONT A DRIER NORTHWEST FLOW DEVELOPS. BOTH THE NAM AND GFS HAVE THE PRECIPITATION BAND PUSHING EAST OF OUR AREA BY 18Z SATURDAY. WE ARE CARRYING CHANCES OF SHOWERS ABOUT 6 HOURS BEHIND THIS TO ACCOUNT FOR THE POSSIBILITY OF EARLIER MODEL RUNS THAT THE FRONT WOULD HANG UP ACROSS OUR AREA...CERTAINLY POSSIBLE THIS TIME OF YEAR. COOLER TEMPERATURES ARE LIKELY SATURDAY IN EITHER EVENT. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... THE GFS AND ECMWF BRING A TROF INTO THE INLAND PACIFIC NORTHWEST BY THE END OF THIS PERIOD WITH A RIDGE REPLACING THE TROF CURRENTLY OVER MINNESOTA. THIS TELECONNECTS TO A WEAKER TROF OVER THE EASTERN U.S. AS THE OLD GREAT LAKES TROF EJECTS INTO EASTERN CANADA. SUNDAY LOOKS LIKE A NICE DAY WITH TEMPERATURES IN THE MID 80/S AND DEW POINTS IN THE 60/S. THE HUMIDITY BEGINS TO RETURN MONDAY AND TUESDAY WITH THE APPROACH OF THE NEXT UPSTREAM TROF AND AN INCREASING SOUTHERLY FLOW. TEMPERATURES RISE BACK INTO THE LOWER 90S BY MONDAY WITH A CHANCE OF THUNDERSTORMS OVER THE MOUNTAINS. THIS THREAT SPREADS INTO THE METRO AREAS TUESDAY AND WEDNESDAY. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... PATCHY FOG EXPECTED ACROSS THE AREA...THOUGH ONLY BRIEFLY DENSE TOWARD SUNRISE IN LOCALIZED AREAS. MOSTLY CLR THIS MRNG...THOUGH CUMULUS DECKS WILL BEGIN TO DEVELOP EARLY AFTN. SCATTERED SHOWERS AND TSTMS WILL DEVELOP THIS MORNING AND MOVE EAST FROM THE MTNS OVER THE COURSE OF THE AFTN AND INTO EARLY EVNG. METRO AREAS COULD SEE THIS ACTIVITY TOWARD LATE AFTN...W/ A LULL PERIOD FOR THE LATE NIGHT HRS. SCATTERED SHOWERS POSSIBLE OVERNIGHT. POTENTIALLY SEVERE THUNDERSTORMS PROGRESS NORTHEAST THROUGH THE MID ATLANTIC FRIDAY WITH HEAVY RAIN AND POSSIBLE STRONG WINDS. THE COLD FRONT STALLS OVER CHESAPEAKE BAY REGION SATURDAY...WITH HIGH PRESSURE AND MAINLY VFR CONDITIONS EXPECTED SUNDAY AND MONDAY. && .MARINE... LIGHT WINDS OVERNIGHT...MAINLY SWLY. A LOW PRESSURE SYSTEM WILL APPROACH TODAY FROM THE NW AND INCREASE THE SFC PRES GRADIENT UP AGAINST THE LARGE BERMUDA HIGH OFF THE COAST. SLY WINDS WILL BEGIN TO CHANNEL AND STRENGTHEN LATER THIS AFTN. A SCA IS NOW POSTED FOR THE BAY - MAINLY THE MAIN CHANNEL. THE PEAK WILL BE THIS EVENING AND INTO THE LATE NIGHT HRS...THEN GRADUALLY SUBSIDE FROM NORTH- TO-SOUTH. SHOWERS AND TSTMS ARE ALSO EXPECTED TO DEVELOP OFF THE WEST LATER THIS AFTN AND APPROACH THE WATERS...CREATING GUSTY WINDS IN LOCALIZED AREAS. SOUTHERLY CHANNELING WILL DEVELOP FRIDAY WITH WIND SPEEDS APPROACHING 15 KTS. WINDS WILL BECOME LOCALLY GUSTY OVER THE WATERS IN THUNDERSTORMS FRIDAY WITH REDUCED VISIBILITIES IN HEAVY DOWNPOURS. A SMALL CRAFT ADVISORY MAY BE NEEDED FRIDAY WITH GUSTY WINDS FROM THUNDERSTORMS INTO FRIDAY NIGHT. FRONT STALLS WITH CONTINUED SHOWERS AND THUNDERSTORMS SATURDAY. HIGH PRESSURE AND FAIR WEATHER IS EXPECTED SUNDAY AND MONDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 10 PM EDT THIS EVENING FOR ANZ530>533-537>542. SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 6 AM EDT FRIDAY FOR ANZ534-543. && $$ SYNOPSIS...GMS NEAR TERM...KRW/GMS SHORT TERM...GMS LONG TERM...SDG AVIATION...GMS/KRW MARINE...GMS/KRW
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
740 PM EDT FRI AUG 10 2012 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 410 PM EDT FRI AUG 10 2012 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER SE LOWER MI. AN EXTENSIVE PCPN SHIELD PERSISTED ON THE NW FLANK OF THE LOW ASSOCIATED WITH THE STRONGER 800-700 MB FGEN/DEFORMATION. TONIGHT...SATELLITE TRENDS AND MODELS KEEP ANY PCPN ASSOCIATED WITH THE SFC/MID LEVEL LOW EAST OF THE CWA.SFC HIGH PRES RIDGE WILL DRIFT E TOWARD UPPER MI TONIGHT...BUT ONLY CLOSE ENOUGH FOR JUST THE FAR W TO SEE LIGHT/CALM WIND AND GOOD RADIATIONAL COOLING CONDITIONS. PWAT VALUES OVER THE WEST FALL INTO THE 0.30 TO 0.50 INCH RANGE. A TIGHTER PRES GRADIENT TO THE EAST WILL MAINTAIN STRONG ENOUGH BNDRY LAYER WINDS TO KEEP TEMPS FROM FALLING OFF AS MUCH. SOME MID OR HIGH CLOUDS OVER THE E WILL ALSO LIMIT TEMP DROP. GUIDANCE TEMPS WERE REASONABLE WITH TEMPS FALLING OFF INTO THE LOWER 40S INLAND WEST...ESPECIALLY IN USUAL COLD SPOTS. SATURDAY...AS THE LOW LIFTS SLOWLY TO THE NE THROUGH SRN ONTARIO...NRLY WINDS WILL ONLY GRADUALLY DIMINISH. WITH 850 MB TEMPS AROUND 9C...MAX READINGS INTO THE LOWER TO MID 70S ARE EXPECTED. FCST SOUNDINGS AND DEEPER MIXING SHOW POTENTIAL FOR DEWPOINTS TO DRAMATICALLY(AOB 40)INLAND. SO...ADJUSTED DEWPOINTS TOWARD LOWER END NAM GUIDANCE WITH AT LEAST LOWER 40S WITH MIN RH VALUES AOB 35 PCT. A HIGH RISK OF RIP CURRENTS REMAINS TONIGHT INTO SATURDAY. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 410 PM EDT FRI AUG 10 2012 THE LATE SUMMER PATTERN WILL BE IN FULL SWING THROUGH THE LONG TERM AS DEEP TROUGHING SLOWLY DEVELOPS OVER EASTERN CANADA. AS A RESULT...A SIGNIFICANT COOL-DOWN LATE NEXT WEEK IS APPEARING MORE LIKELY WITH EACH PASSING DAY. SATURDAY NIGHT THROUGH MONDAY...THE STACKED CLOSED LOW THAT IS BRINGING HEAVY PRECIPITATION TO PORTIONS OF LOWER MI TODAY WILL CONTINUE DRIFTING NORTHEAST THROUGH SATURDAY...EVENTUALLY REACHING GEORGIAN BAY BY 00Z SUNDAY. BOTH THE NAM AND GFS CONTINUE TO INDICATE AN ENHANCED BAND OF H7 DEFORMATION PUSHING NW INTO FAR EASTERN UPPER MI...WITH THE NAM BEING THE MOST AGGRESSIVE. BUT GIVEN THAT THE NAM HAS OVERDONE MOISTURE WITH THIS SYSTEM AND THAT THERE WILL BE SIGNIFICANT DRY AIR IN PLACE ABOVE 800 MB...DO NOT THINK ANY PRECIP WILL MAKE IT INTO THE CWA. A BRIEF SHORTWAVE RIDGE WILL THEN MOVE ACROSS THE AREA LATE SATURDAY NIGHT INTO SUNDAY AND BRING MOSTLY CLEAR SKIES. SOME HIGH CLOUDS MAY REMAIN OVER THE EAST HALF AS A RESULT OF THE LEFT ENTRANCE TO A WEAK UPPER JET ON THE BACKSIDE OF THE DEPARTING MID-LEVEL LOW. TEMPS COULD FALL A DECENT AMOUNT ACROSS THE INTERIOR WEST HALF WITH LIGHT WINDS...VERY DRY AIR...AND MINIMAL CLOUD COVER. HAVE DROPPED TEMPS INTO THE LOWER FOR SOME OF THE NORMAL COLD SPOTS. AS MENTIONED IN THE PREVIOUS FORECAST...IT APPEARS A CONVECTIVELY INDUCED SHORTWAVE WILL DEVELOP SATURDAY NIGHT ACROSS THE NORTHERN PLAINS. THIS WAVE IS PROGGED TO ERODE THE RIDGE AND MOVE SOUTHEAST INTO SOUTHERN MN/NORTHERN IA BY 00Z MONDAY. MEANWHILE...A LARGER MID-LEVEL TROUGH OVER NORTHERN SASKATCHEWAN AT 00Z SUNDAY WILL MOVE TO THE EAST THROUGH THE WEEKEND...REACHING FAR NORTHERN QUEBEC BY 18Z MONDAY. AN EXTENSION OF THIS TROUGH AND AN ASSOCIATED COLD FRONT SHOULD TRACK ACROSS THE CWA MONDAY AS IT PICKS UP THE SHORTWAVE IN THE UPPER MISSISSIPPI VALLEY. THE ECMWF HAS TRENDED MUCH FASTER WITH THE TROUGH OVER THE PAST FEW RUNS...WHILE THE GFS HAS ACTUALLY SLOWED THE TROUGH. FOR NOW...WILL STICK WITH THE IDEA THAT IT WILL COME THROUGH SOMETIME ON MONDAY...BEGINNING WITH THE WEST IN THE MORNING AND ENDING WITH THE EAST IN THE LATE AFTERNOON. THE TROUGH WILL BE STARVED OF LOW-LEVEL MOISTURE AS THE CONVECTIVE COMPLEX TO THE SOUTH SHOULD PREVENT MOST NORTHWARD FLOW OF MOISTURE. SOME SUNSHINE WILL MAKE IT THROUGH THE CLOUDS...ALLOWING SBCAPE VALUES TO REACH A FEW HUNDRED J/KG. EXTRA LIFTING SUPPORT FROM WEAK LAKE BREEZES WILL LIKELY ALLOW SOME ISOLATED TO SCATTERED SHOWERS AND A FEW THUNDERSTORMS TO DEVELOP INLAND...MAINLY IN THE AFTERNOON. THIS ACTIVITY WILL SPREAD EASTWARD ALONG THE FRONT BEFORE CLEARING OUT EARLY MONDAY EVENING. DEW POINTS WILL BE A CONCERN ON SUNDAY WITH ABUNDANT SUNSHINE AND A SHARP TRANSITION TO DRY AIR ABOVE THE MIXED LAYER. FORECAST H8 DEW POINTS ARE AROUND 8C...BUT QUICKLY DROP TO -10 TO -20C BY H7. WINDS WILL BE LIGHT THOUGH...SO DECENT ENTRAINMENT OF THE DRY AIR MAY BE LIMITED. WILL LOWER DEW POINTS TO THE UPPER 40S INTERIOR WEST IN THE AFTERNOON. MONDAY NIGHT THROUGH WEDNESDAY...A MID-LEVEL RIDGE WILL BEGIN TO BUILD IN FROM THE WEST MONDAY NIGHT AND BRING MOSTLY CLEAR SKIES THROUGH WEDNESDAY. POPS WERE REMOVED WEDNESDAY AS THE ECMWF...WHICH HAD POPS IN THE FORECAST YESTERDAY...HAS LINED UP WITH THE GFS IN SHARPENING THE RIDGE AND KEEPING THE AREA DRY. MORE ABUNDANT MIXING DAYS COULD BE IN STORE TUESDAY AND WEDNESDAY AS VERY DRY AIR REMAINS ABOVE THE MIXED LAYER. WEDNESDAY WILL BE OF MORE CONCERN AS TEMPERATURES WILL RISE TO AROUND 80 AND DEW POINTS WILL POSSIBLY FALL WELL INTO THE 50S. AS OF NOW...FORECAST MIN RH VALUES WILL BE IN THE LOW 40S FOR THE INTERIOR WEST. HOWEVER...MIXING MAY BE EVEN MORE AGGRESSIVE THAN CURRENTLY FORECAST...SO RH VALUES MAY FALL INTO THE 30S. WINDS WILL REMAIN RATHER LIGHT...LESS THAN 15 MPH...SO FIRE WX CONCERNS ARE LIMITED RIGHT NOW. WEDNESDAY NIGHT AND FRIDAY...A SIGNIFICANT CHANGE IN THE WEATHER PATTERN APPEARS TO BE IN THE MAKING WEDNESDAY NIGHT. A SHORTWAVE TROUGH CURRENTLY OVER THE GULF OF ALASKA WILL MOVE EAST THROUGH THE SOUTHERN CANADIAN PROVINCES THROUGH THE WEEKEND WHILE PICKING UP ENERGY AND MUCH COOLER H8 AIR FROM A POLAR VORTEX WEST OF GREENLAND. GUIDANCE IS RATHER CONSISTENT WITH THE HANDLING OF THIS TROUGH THROUGH WEDNESDAY NIGHT...BUT SOLUTIONS BEGIN TO DIVERGE BY THURSDAY. THE ECMWF AND GEM BRING THE TROUGH NORTHEASTWARD MUCH QUICKER THAN THE GFS. THE ECMWF THEN TRIES TO DEVELOP A CLOSED LOW OVER THE CWA ON FRIDAY...RESULTING IN PLENTY OF RAIN. SOLUTIONS ARE MUCH TOO INCONSISTENT AND DIVERGENT AT THIS POINT TO MAKE ANY SENSE OF TIMING AND PRECIP...BUT ALL STILL HINT AT A MUCH COOLER END TO THE WEEK...WITH HIGHS POSSIBLY AROUND 60 IN SOME PLACES ON FRIDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 736 PM EDT FRI AUG 10 2012 UNDER DRY AIR MASS ASSOCIATED WITH HIGH PRES DRIFTING INTO THE UPPER LAKES...VFR CONDITIONS WILL BE THE RULE THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 410 PM EDT FRI AUG 10 2012 EXPECT THE STRONGEST WINDS DURING THE FCST PERIOD TO OCCUR TONIGHT THROUGH SAT UNDER RELATIVELY TIGHT PRES GRADIENT BTWN LOW PRES DRIFTING NNE INTO SRN ONTARIO AND HIGH PRES DRIFTING E TOWARD THE UPPER LAKES. CLOSER TO APPROACHING HIGH...WINDS WILL BE LIGHTEST OVER WRN LAKE SUPERIOR... GENERALLY 10-20KT. OVER THE E...NNE WINDS WILL BE MOSTLY IN THE 15-25KT RANGE. WINDS WILL SLOWLY DIMINISH TONIGHT INTO SAT...BUT WINDS WILL REMAIN AOA 20 KT OVER ERN LAKE SUPERIOR TIL LATE SAT. WINDS SUN THRU TUE WILL BE MOSTLY 15KT OR LESS AS ONLY WEAK SYSTEMS AFFECT THE AREA. A FALL-LIKE LOW PRESSURE SYSTEM AND FRONT MOVING THROUGH LAKE SUPERIOR THURSDAY INTO FRIDAY COULD BRING STRONGER NW WINDS INTO THE 20-30 KT RANGE. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...TK AVIATION...ROLFSON MARINE...JLB
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
136 PM EDT THU AUG 9 2012 .SYNOPSIS... ISSUED AT 321 AM EDT THU AUG 9 2012 AN UPPER LEVEL LOW PRESSURE SYSTEM WILL BRING RAIN AND UNSEASONABLY COOL WEATHER TODAY THROUGH FRIDAY. HIGH TEMPERATURES WILL ONLY REACH THE MID 60S TO MID 70S TODAY AND FRIDAY. IT WILL ALSO BECOME RATHER BREEZY LATE TONIGHT THROUGH FRIDAY. A FEW LIGHTER SHOWERS MAY LINGER INTO SATURDAY BUT MOST OF THE WEEKEND SHOULD BE DRY. && .UPDATE... ISSUED AT 750 AM EDT THU AUG 9 2012 I UPDATED THE GRIDS TO TRACK THE AREA OF CONVECTION NEAR JACKSON OUT AN BRING THE AREA OF RAIN NORTH OF MKG IN. I KEPT KEPT THE TREAT OF THUNDERSTORMS THIS AFTERNOON DUE TO THE STRENGTH OF THE DYNAMICS WITH THIS DIGGING SYSTEM AND THE DEVELOPING MID LEVEL JET SEGMENT SHOWN BY THE LATEST RAP (09Z) OVER CENTRAL LOWER MICHIGAN AFTER 18Z CAUSING COUPLING WITH THE EXIT REGION OF THE JET SEGMENT DIVING INTO IL AT THAT TIME. THIS SHOULD HELP PULL MID LEVEL UNSTABLE AIR NORTH OVER THE EASTERN CWA LATE THIS AFTERNOON. THE HEAVY RAIN THREAT WILL HAVE TO BE WATCHED... I COULD SEE A NEED FOR URBAN AND SMALL STREAM FLOODING ADVISORIES BY THIS EVENING AS THE RAIN BAND COMES TOGETHER OVER OUR CWA. && .SHORT TERM...(TODAY THROUGH SATURDAY AFTERNOON) ISSUED AT 321 AM EDT THU AUG 9 2012 AN UPPER LEVEL LOW PRESSURE SYSTEM IN CONJUNCTION WITH AN INTENSIFYING SFC LOW TRACKING NE ACROSS OHIO TONIGHT WILL BRING RAIN AND UNSEASONABLY COOL CONDITIONS TODAY THROUGH FRIDAY. MAX TEMPS TODAY WILL ONLY REACH THE UPPER 60S TO MID 70S. IT WILL BE EVEN COOLER FRIDAY WITH STRONG NORTH WINDS... EXTENSIVE LOW CLOUDS AND SHOWERS. MAX TEMPS FRIDAY WILL ONLY REACH THE MID 60S TO NEAR 70. MAINTAINING VERY HIGH (CATEGORICAL) POPS FOR RAIN TODAY THROUGH TONIGHT. LOCALLY HEAVY RAIN IS POSSIBLE WITH DEEP MOISTURE IN PLACE AND HIGH PRECIPITABLE WATER VALUES. ON AVERAGE A GENERAL ONE TO TWO INCH TYPE RAINFALL IS LIKELY FOR MOST OF OUR FCST AREA FROM TODAY THROUGH FRIDAY BUT A FEW HIGHER TOTALS ARE POSSIBLE. MOST (IF NOT ALL) CONVECTIVE DEVELOPMENT TODAY THROUGH TONIGHT SHOULD STAY SOUTH OF OUR FCST AREA ACROSS IN/OH WHERE SOME DECENT SFC/ELEVATED INSTABILITY WILL DEVELOP LATER TODAY THROUGH TONIGHT. EXTENSIVE CLOUD COVER WILL LIKELY LINGER ON SATURDAY BUT ANY LINGERING LIGHTER SHOWERS SHOULD GRADUALLY TAPER OFF AS THE UPPER TROF AXIS SHIFTS A LITLE FURTHER ENE AWAY FROM OUR REGION. .LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 321 AM EDT THU AUG 9 2012 THERE WILL BE SLOW WARMING TREND UNTIL THE NEXT SYSTEM COMES THROUGH LATE IN THE WEEK. COULD BE AN ACTIVE THUNDERSTORM EVENT LATE WEEK WITH THE FRONT. THE MODELS DO AGREE OVER ALL ON THE LARGE SCALE UPPER WAVE PATTERN. THAT IS THE SOUTHERN BRANCH OF THE POLAR JET SLOWLY DIGS SOUTH OVER THE WESTERN CONUS THROUGH AT LEAST WEDNESDAY. THAT IN TURN RESULTS IN RISING HEIGHTS OVER THE CENTRAL CONUS INTO MID WEEK. THIS ALL HAPPENS DUE TO THE STORM SYSTEM THAT IS CURRENTLY NEAR THE NORTH POLE DIGGING SOUTH SOUTHEAST INTO WESTERN AND CENTRAL CANADA DURING THIS SAME TIME(SUNDAY INTO WEDNESDAY). THAT RESULTS IN THE LARGE UPPER HIGH THAT HAS BEEN CAUSING ALL THE HOT WEATHER FOR THE PAST FEW MONTHS... OVER MOST OF THE CONUS... TO FINALLY BE SQUASHED AND SHIFTED TO THE GULF OF MEXICO BY WEDNESDAY. THE RISING HEIGHTS WOULD MEAN WARMER TEMPERATURES HEAR AGAIN (BUT JUST FOR A SHORT TIME). AS I WROTE YESTERDAY THROUGH... LARGE SCALE CHANGES IN THE PLANETARY WAVE PATTERN ARE CURRENTLY UNDERWAY. I DO NOT EXPECT ANOTHER BIG HEAT WAVE FROM THIS WARM UP. A STRONG COLD FRONT FOLLOWS LATE IN THE WEEK. THAT WILL BE PROCEEDED BY THUNDERSTORMS. HOWEVER THAT WILL BE JUST BEYOND OUR CURRENT FORECAST PERIOD. THE EVENT LATE WEEK COULD BE A SIGNIFICANT STORM EVENT FROM WHAT BOTH THE GFS AND ECMWF SUGGEST. REMEMBER WE HAVE A POLAR LOW DIGGING SOUTH THAT MAY PHASE WITH PACIFIC STORM IN THAT TIME FRAME. AS FOR THE DAY TO DAY...OUR CLOSED UPPER LOW SHOULD BE DEPARTING THE WESTERN GREAT LAKES SATURDAY NIGHT INTO SUNDAY. HIGH PRESSURE WILL BRING SUNSHINE AND TYPICAL MID AUGUST TEMPERATURES. A WEAK SYSTEM WILL MOVE THROUGH THE WESTERN GREAT LAKES IN THE MONDAY TIME FRAME. THAT SYSTEM IS CURRENTLY MOVING ON SHORE OVER THE WESTERN CONUS AND IS THE KICKER THAT HELPS TO BOOT THE UPPER LOW OUT OF THE GREAT LAKES. THE MODELS ARE STRUGGLING WITH IT BUT NO MATTER... IT IS WEAK SYSTEM AND SHOULD HAVE A LIMITED IMPACT TO SOUTHWEST MICHIGAN WEATHER IN THE MONDAY TIME FRAME...ISOLATED SHOWERS AT BEST. THE REAL WARM UP WILL BE TUESDAY AND WEDNESDAY. STORMS WILL FOLLOW... OF COURSE THERE IS ALWAYS TIMING ISSUES WITH SUCH FRONTS BUT WE WILL HAVE TO WATCH THIS ONE. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 136 PM EDT THU AUG 9 2012 NOT MUCH CHANGE TO THE FORECAST. UPPER LOW WILL CONTINUE TO MOVE TOWARD LOWER MICHIGAN RESULTING IN SHOWERS AND LOWER CIGS. NE WIND FLOW WILL ADVECT ADDITIONAL LOW LEVEL MOISTURE SWWD WHICH WILL LEAD TO SOME IFR CIGS. CIGS WON/T ALWAYS BE IFR AND VSBYS WILL BE P6SM AT TIMES. BOTH WILL BOUNCE UP AND DOWN THROUGH THE NEXT 24 HRS. THE UPPER LOW WILL BE SLOW TO MOVE ACROSS THE AREA. && .MARINE... ISSUED AT 321 AM EDT THU AUG 9 2012 WINDS AND WAVES WILL RAMP UP SIGNIFICANTLY TONIGHT THROUGH FRIDAY. WATERSPOUTS ARE ALSO POSSIBLE BY THIS AFTERNOON THROUGH TONIGHT INTO FRIDAY. && .HYDROLOGY... ISSUED AT 321 AM EDT THU AUG 9 2012 CUMULATIVE RAINFALL TOTALS FROM TODAY THROUGH FRIDAY OF AN INCH OR TWO ARE LIKELY ACROSS MUCH OF OUR FCST AREA. NO SIGNIFICANT HYDRO ISSUES ARE ANTICIPATED THOUGH GIVEN LOW RIVER LEVES/DRY ANTECEDENT CONDITIONS ALTHOUGH RIVER LEVELS WILL COME UP SOMEWHAT IN RESPONSE TO THIS PROLONGED RAIN EVENT. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...GALE WATCH FROM FRIDAY MORNING THROUGH SATURDAY MORNING FOR LMZ844>849. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT FRIDAY FOR LMZ844>849. && $$ UPDATE...WDM SYNOPSIS...LAURENS SHORT TERM...LAURENS LONG TERM...WDM AVIATION...93 HYDROLOGY...LAURENS MARINE...LAURENS
AREA FORECAST DISCUSSION
NWS GRAND RAPIDS MI
752 AM EDT THU AUG 9 2012 .SYNOPSIS... ISSUED AT 321 AM EDT THU AUG 9 2012 AN UPPER LEVEL LOW PRESSURE SYSTEM WILL BRING RAIN AND UNSEASONABLY COOL WEATHER TODAY THROUGH FRIDAY. HIGH TEMPERATURES WILL ONLY REACH THE MID 60S TO MID 70S TODAY AND FRIDAY. IT WILL ALSO BECOME RATHER BREEZY LATE TONIGHT THROUGH FRIDAY. A FEW LIGHTER SHOWERS MAY LINGER INTO SATURDAY BUT MOST OF THE WEEKEND SHOULD BE DRY. && .UPDATE... ISSUED AT 750 AM EDT THU AUG 9 2012 I UPDATED THE GRIDS TO TRACK THE AREA OF CONVECTION NEAR JACKSON OUT AN BRING THE AREA OF RAIN NORTH OF MKG IN. I KEPT KEPT THE TREAT OF THUNDERSTORMS THIS AFTERNOON DUE TO THE STRENGTH OF THE DYNAMICS WITH THIS DIGGING SYSTEM AND THE DEVELOPING MID LEVEL JET SEGMENT SHOWN BY THE LATEST RAP (09Z) OVER CENTRAL LOWER MICHIGAN AFTER 18Z CAUSING COUPLING WITH THE EXIT REGION OF THE JET SEGMENT DIVING INTO IL AT THAT TIME. THIS SHOULD HELP PULL MID LEVEL UNSTABLE AIR NORTH OVER THE EASTERN CWA LATE THIS AFTERNOON. THE HEAVY RAIN THREAT WILL HAVE TO BE WATCHED... I COULD SEE A NEED FOR URBAN AND SMALL STREAM FLOODING ADVISORIES BY THIS EVENING AS THE RAIN BAND COMES TOGETHER OVER OUR CWA. && .SHORT TERM...(TODAY THROUGH SATURDAY AFTERNOON) ISSUED AT 321 AM EDT THU AUG 9 2012 AN UPPER LEVEL LOW PRESSURE SYSTEM IN CONJUNCTION WITH AN INTENSIFYING SFC LOW TRACKING NE ACROSS OHIO TONIGHT WILL BRING RAIN AND UNSEASONABLY COOL CONDITIONS TODAY THROUGH FRIDAY. MAX TEMPS TODAY WILL ONLY REACH THE UPPER 60S TO MID 70S. IT WILL BE EVEN COOLER FRIDAY WITH STRONG NORTH WINDS... EXTENSIVE LOW CLOUDS AND SHOWERS. MAX TEMPS FRIDAY WILL ONLY REACH THE MID 60S TO NEAR 70. MAINTAINING VERY HIGH (CATEGORICAL) POPS FOR RAIN TODAY THROUGH TONIGHT. LOCALLY HEAVY RAIN IS POSSIBLE WITH DEEP MOISTURE IN PLACE AND HIGH PRECIPITABLE WATER VALUES. ON AVERAGE A GENERAL ONE TO TWO INCH TYPE RAINFALL IS LIKELY FOR MOST OF OUR FCST AREA FROM TODAY THROUGH FRIDAY BUT A FEW HIGHER TOTALS ARE POSSIBLE. MOST (IF NOT ALL) CONVECTIVE DEVELOPMENT TODAY THROUGH TONIGHT SHOULD STAY SOUTH OF OUR FCST AREA ACROSS IN/OH WHERE SOME DECENT SFC/ELEVATED INSTABILITY WILL DEVELOP LATER TODAY THROUGH TONIGHT. EXTENSIVE CLOUD COVER WILL LIKELY LINGER ON SATURDAY BUT ANY LINGERING LIGHTER SHOWERS SHOULD GRADUALLY TAPER OFF AS THE UPPER TROF AXIS SHIFTS A LITLE FURTHER ENE AWAY FROM OUR REGION. .LONG TERM...(SATURDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 321 AM EDT THU AUG 9 2012 THERE WILL BE SLOW WARMING TREND UNTIL THE NEXT SYSTEM COMES THROUGH LATE IN THE WEEK. COULD BE AN ACTIVE THUNDERSTORM EVENT LATE WEEK WITH THE FRONT. THE MODELS DO AGREE OVER ALL ON THE LARGE SCALE UPPER WAVE PATTERN. THAT IS THE SOUTHERN BRANCH OF THE POLAR JET SLOWLY DIGS SOUTH OVER THE WESTERN CONUS THROUGH AT LEAST WEDNESDAY. THAT IN TURN RESULTS IN RISING HEIGHTS OVER THE CENTRAL CONUS INTO MID WEEK. THIS ALL HAPPENS DUE TO THE STORM SYSTEM THAT IS CURRENTLY NEAR THE NORTH POLE DIGGING SOUTH SOUTHEAST INTO WESTERN AND CENTRAL CANADA DURING THIS SAME TIME(SUNDAY INTO WEDNESDAY). THAT RESULTS IN THE LARGE UPPER HIGH THAT HAS BEEN CAUSING ALL THE HOT WEATHER FOR THE PAST FEW MONTHS... OVER MOST OF THE CONUS... TO FINALLY BE SQUASHED AND SHIFTED TO THE GULF OF MEXICO BY WEDNESDAY. THE RISING HEIGHTS WOULD MEAN WARMER TEMPERATURES HEAR AGAIN (BUT JUST FOR A SHORT TIME). AS I WROTE YESTERDAY THROUGH... LARGE SCALE CHANGES IN THE PLANETARY WAVE PATTERN ARE CURRENTLY UNDERWAY. I DO NOT EXPECT ANOTHER BIG HEAT WAVE FROM THIS WARM UP. A STRONG COLD FRONT FOLLOWS LATE IN THE WEEK. THAT WILL BE PROCEEDED BY THUNDERSTORMS. HOWEVER THAT WILL BE JUST BEYOND OUR CURRENT FORECAST PERIOD. THE EVENT LATE WEEK COULD BE A SIGNIFICANT STORM EVENT FROM WHAT BOTH THE GFS AND ECMWF SUGGEST. REMEMBER WE HAVE A POLAR LOW DIGGING SOUTH THAT MAY PHASE WITH PACIFIC STORM IN THAT TIME FRAME. AS FOR THE DAY TO DAY...OUR CLOSED UPPER LOW SHOULD BE DEPARTING THE WESTERN GREAT LAKES SATURDAY NIGHT INTO SUNDAY. HIGH PRESSURE WILL BRING SUNSHINE AND TYPICAL MID AUGUST TEMPERATURES. A WEAK SYSTEM WILL MOVE THROUGH THE WESTERN GREAT LAKES IN THE MONDAY TIME FRAME. THAT SYSTEM IS CURRENTLY MOVING ON SHORE OVER THE WESTERN CONUS AND IS THE KICKER THAT HELPS TO BOOT THE UPPER LOW OUT OF THE GREAT LAKES. THE MODELS ARE STRUGGLING WITH IT BUT NO MATTER... IT IS WEAK SYSTEM AND SHOULD HAVE A LIMITED IMPACT TO SOUTHWEST MICHIGAN WEATHER IN THE MONDAY TIME FRAME...ISOLATED SHOWERS AT BEST. THE REAL WARM UP WILL BE TUESDAY AND WEDNESDAY. STORMS WILL FOLLOW... OF COURSE THERE IS ALWAYS TIMING ISSUES WITH SUCH FRONTS BUT WE WILL HAVE TO WATCH THIS ONE. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 750 AM EDT THU AUG 9 2012 THE CONVECTION OVER JXN WILL DEPART BY 13Z... MORE LIKELY BY 1215Z ACTUALLY. THE BKN005 CIGS AT LAN SHOULD BE GONE BY 13Z TOO AS NO OTHER SITES HAVE THAT SORT OF CEILING NEAR THERE. FOR THE MOST PART I EXPECT VFR CIGS/VSBY MOST OF THE REST OF THE MORNING AT OUR TAF SITES. AS THE STORM STARTS TO COME TOGETHER MID TO LATE AFTERNOON ALL TAF SITES SHOULD SEE MVFR TO IFR VSBY AND IFR CIGS. THAT WILL CONTINUE INTO FRIDAY AFTERNOON AS THE STORM CONTINUES TO DEVELOP. && .MARINE... ISSUED AT 321 AM EDT THU AUG 9 2012 WINDS AND WAVES WILL RAMP UP SIGNIFICANTLY TONIGHT THROUGH FRIDAY. WATERSPOUTS ARE ALSO POSSIBLE BY THIS AFTERNOON THROUGH TONIGHT INTO FRIDAY. && .HYDROLOGY... ISSUED AT 321 AM EDT THU AUG 9 2012 CUMULATIVE RAINFALL TOTALS FROM TODAY THROUGH FRIDAY OF AN INCH OR TWO ARE LIKELY ACROSS MUCH OF OUR FCST AREA. NO SIGNIFICANT HYDRO ISSUES ARE ANTICIPATED THOUGH GIVEN LOW RIVER LEVES/DRY ANTECEDENT CONDITIONS ALTHOUGH RIVER LEVELS WILL COME UP SOMEWHAT IN RESPONSE TO THIS PROLONGED RAIN EVENT. && .GRR WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...GALE WATCH FROM FRIDAY MORNING THROUGH SATURDAY MORNING FOR LMZ844>849. SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 6 AM EDT FRIDAY FOR LMZ844>849. && $$ UPDATE...WDM SYNOPSIS...LAURENS SHORT TERM...LAURENS LONG TERM...WDM AVIATION...WDM HYDROLOGY...LAURENS MARINE...LAURENS
AREA FORECAST DISCUSSION...UPDATE
NWS JACKSON MS
1035 AM CDT THU AUG 9 2012 .UPDATE...RECIPE FOR LOCALIZED HEAVY RAINFALL IN PLACE THIS MORNING UP ALONG AND HIGHWAY 82 CORRIDOR IN CENTRAL MISSISSIPPI AS A RATHER STRONG SUMMER TROUGH DIVES SOUTHEAST INTO THE REGION. WARM AIR AND MOISTURE ADVECTION EARLIER THIS MORNING KICKED OFF A SLOW MOVING CLUSTER OF THUNDERSTORMS IN THIS NEIGHBORHOOD THAT HAS SINCE SHOWN A STRONG TENDENCY TO BACK-BUILD AND TRAIN ACTIVITY OVER SIMILAR AREAS. THIS TENDENCY IS EXPLAINED WELL BY LATEST RUC ANALYSIS REVEALING 850 MB CORFIDI VECTOR RIDGING JUXTAPOSING ITSELF IN THE SAME GENERAL REGION. MIX OF MODELS AND ANALYSIS ALSO REVEAL SUBTLE RIGHT ENTRANCE REGION JET STREAM DYNAMICS COULD ALSO BE IMPARTING ADDITIONAL ATMOSPHERIC LIFT TO THE SITUATION. BY EARLY AFTERNOON (AND HOPEFULLY BEFORE) THE ATMOSPHERIC SITUATION PRODUCING THE TRAINING CONVECTION SHOULD EVOLVE TO THE POINT WHERE ACTIVITY WILL PROGRESS SOUTHEAST (AND THUS NOT TRAIN AND BE SUCH A FLASH FLOOD WORRY). OTHERWISE...SHOWERS AND STORMS IN THE FORECAST AREA SO FAR THIS MORNING HAVE MAINLY BEEN CONFINED TO THE AFOREMENTIONED HIGHWAY 82 CORRIDOR. HOWEVER...THIS SHOULD CHANGE IN THE NEXT FEW HOURS SINCE THE INCOMING UPPER TROUGH IS IMPARTING MORE AND MORE LIFT ACROSS THE WHOLE OF THE REGION AND FAVORABLE MOISTURE ADVECTION VECTORS ARE EVOLVING. BEST CHANCES FOR STORMS WILL OF COURSE BE RIGHT NOW IN NORTH-CENTRAL AND NORTHEASTERN ZONES (WHERE IT IS RAINING LIKE HECK)...BUT IN 2 TO 3 HOURS THE BEST CHANCES WILL SHIFT TO AREAS ROUGHLY ALONG AND SOUTH OF THE NATCHEZ TRACE CORRIDOR THROUGH MID TO LATE AFTERNOON. FORTUNATELY...WE DO NOT EXPECT A REPEAT OF BIG FLOODING WORRIES FURTHER SOUTH IN THE REGION TODAY...ALTHOUGH COMBINATION OF MODEST SHEAR/MODEST INSTABILITY AND AMPLE LIFT WILL UNDOUBTEDLY BE ENOUGH TO GENERATE SOME STRONG TO OCCASIONAL SEVERE STORMS. MAIN RISK WITH THE MOST INTENSE STORMS WILL BE DAMAGING WINDS AND HAIL UP TO QUARTER SIZE OR SO. BY LATE THIS AFTERNOON WE ANTICIPATE MOST STORMS ASSOCIATED WITH FIRST SHORT WAVE SHOULD BE EXITING TO THE EAST OR SOUTH OF THE FORECAST AREA WHILE ANOTHER VIGOROUS SHORT WAVE (ASSOCIATED WITH AN ACTUAL COLD FRONT) COMES PLOWING TOWARDS THE AREA FROM THE NORTH. THIS WILL LIKELY BRING ADDITIONAL THUNDERSTORM CHANCES TO AT LEAST NORTHERN ZONES BY EARLY THIS EVENING (IF NOT A LITTLE EARLIER)...WITH AGAIN A POTENTIAL FOR SOME SEVERE ACTIVITY TO BE THROWN IN THE MIX. EXPECT MORE TO COME WITH THE MAIN AFTERNOON FORECAST PACKAGE...BUT FOR NOW I HAVE MAINLY ADJUSTED FORECAST SOME TO ACCOUNT FOR LOCALLY HEAVY RAIN IN NORTHEASTERN ZONES. TO HWO IS ALSO BEING TWEAKED IN RESPONSE TO THIS RISK. /BB/ && .PREV DISCUSSION... /ISSUED 319 AM CDT THU AUG 9 2012/ SHORT TERM...COMPLEX CONVECTIVE FORECAST FOR THIS SHORT TERM AS THE EVOLVING MEAN LONG WAVE TROUGH WILL CONTAIN MULTIPLE S/WV`S WHICH WILL DRIVE THE SENSIBLE WEATHER FOR EACH PERIOD. OVERALL...THE MODELS ARE TRYING TO MAKE SENSE OF IT ALL AND I FEEL GOOD ABOUT WHAT I HAVE TO WORK WITH GIVEN THE COMPLEXITY OF THE SITUATION. TO START...THE INITIAL S/WV IS OVER THE W/NW PART OF THE CWA AND IS CURRENTLY BEGINNING TO GEN UP SOME SHRA/TSRA ACTIVITY ACROSS THAT AREA. LOOK FOR THIS TO EXPAND IN COVERAGE THROUGH EARLY/MID MORNING ACROSS THE NW HALF OF THE CWA. AS LIFT FROM THIS FEATURE SHIFTS E/SE...THE LOW LEVEL RESPONSE AND MOISTURE CONVERGENCE WILL FOLLOW SUIT. I SEE THE CENTRAL AND SE HALF OF THE AREA GETTING SOMEWHAT OF AN EARLY START TO THE CONVECTION. BEST PRECIP CHANCES FOR THIS AREA LOOK TO BE LATE MORNING THROUGH EARLY AFTERNOON. AS THIS OCCURS...THE NW HALF WILL SEE A BREAK AND HAVE SOME TIME TO WARM UP AND DESTABILIZE AHEAD OF THE NEXT S/WV (MORE ON THAT IN A BIT). FOR THE SE HALF AND EASTERN PORTIONS...CONCERNING STRONG/SVR STORM POTENTIAL. I`M NOT REAL HIGH ON THIS...MAINLY DUE TO THE EARLY START OF ACTIVITY. HOWEVER...THERE WILL EXIST SOME ENHANCED MID LEVEL FLOW ASSOCIATED WITH OUR S/WV ALONG WITH SOME MID LEVEL COOLING. ADDITIONALLY...BETTER THAN AVG FORCING WILL EXIST AS WELL AND I CAN SEE SOME STRONG STORMS WITH A COUPLE SVR CELLS MIXED IN. AGAIN...THIS IS FOR THE SE HALF AND EASTERN PORTIONS FROM 11AM THROUGH 4PM. MAIN RISK LOOKS TO BE FROM 40-60 MPH WINDS AND LIGHTNING AS STORMS MOVE GENERALLY WEST TO EAST. SHIFTING TO THE SECOND S/WV AND FOCUSING BACK TOWARD THE NW HALF OF THE CWA FOR LATE AFTERNOON/EVENING. THIS PORTION OF THE CWA WILL HAVE THE OPPORTUNITY TO WARM INTO MID 90S. ADDITIONALLY...TEMPS ALOFT WILL REMAIN COOLER THAN AVG AND PROMOTE FAIRLY STEEP LAPSE RATES WITH VERTICAL TOTALS AROUND 28C. THIS 2ND S/WV WILL CONTAIN A STRONGER MID LEVEL SPEED MAX ALONG WITH AN ASSOCIATED MID LEVEL DRY PUNCH DIVING SE ACROSS THE SOUTHERN PLAINS. IT IS THIS PART OF THE CWA WHERE I`M MORE CONCERNED WITH SVR STORMS BETWEEN 5 PM AND MIDNIGHT. ADDITIONAL ACTIVITY LOOKS TO LINGER PAST MIDNIGHT AS WELL...JUST LIKELY NOT STRONG. HAZARDS FROM THIS ACTIVITY WILL BE 60 MPH WINDS...QUARTER HAIL AND POTENTIALLY MORE INTENSE LIGHTNING. I WILL CONSTRUCT GRAPHICS TO ILLUSTRATE EACH RISK ALONG WITH SEGMENTING THE HWO TO FIT THE SITUATION. LASTLY...LOCALLY HEAVY RAIN WILL BE POSSIBLE WITH ANY STORM. ON TO FRI...THIS PERIOD IS A CHALLENGE AS WELL...BUT I`M FEELING MORE CONFIDENT WITH THE MAJORITY OF THE ACTIVITY OCCURRING ACROSS THE SOUTH HALF. THE MAIN ISSUE WITH THIS PERIOD IS TIMING. ALL INDICATIONS ARE...ACTIVITY MAY BE AT THE START OF THE FRI PERIOD...OR GET A QUICK START. FOR NOW...WILL NOT GO WITH SPECIFIC TIMING ON POPS DUE TO THE UNCERTAINTY. THE BEST DEEP MOISTURE LOOKS TO BE ALONG AND SOUTH OF I-20 AS THE DRIER MID LEVEL AIR ASSOCIATED WITH THE S/WV WILL LIKELY BE OVER THE NORTHERN CWA. ALSO...A MORE PRONOUNCED NW FLOW WILL EXIST AND ANY STORMS SHOULD MOVE OFF TO THE SE. AS FOR STRONG STORMS FRI...NOT REALLY EXPECTING MUCH AS THE ONLY THING GOING FOR IT WOULD BE STRONGER OVERALL WINDS ALOFT. LAPSE RATES WILL BE RATHER TAME AND INSTABILITY WILL BE LIMITED. AT THIS POINT...I WOULD BE BEST TO NOT MENTION ANY RISK ON FRI AND SEE HOW THINGS ARE SETUP AFTER WE DEAL WITH THESE FIRST TWO PERIODS. /CME/ LONG TERM...SATURDAY THROUGH NEXT THURSDAY...BEHIND THE PASSAGE OF FRIDAY/FRIDAY NIGHT`S COLD FRONT...A DRIER AIRMASS WILL FILTER SOUTH INTO THE REGION FOR THE WEEKEND. WHILE THIS WILL RESULT IN SLIGHTLY COOLER AFTERNOON AND OVERNIGHT TEMPERATURES...THE BIGGER STORY WILL BE THE NOTICEABLY...AND MUCH APPRECIATED...LESS HUMID CONDITIONS FELT ACROSS THE FORECAST AREA AS DEW POINTS DROP FROM THE MID 70S WE`VE SEEN THROUGH MUCH OF THE SUMMER...DOWN INTO THE LOW AND MIDDLE 60S. AS FAR AS TEMPERATURES ARE CONCERNED FOR THE WEEKEND...AS STATED ABOVE THEY`LL BE SLIGHTLY COOLER. I ADJUSTED HIGHS UP A BIT ON SATURDAY RESULTING IN THEIR RANGING FROM THE MID 80S TO LOWER 90S... WHICH IS WARMER THAN MOS YET COOLER THAN THE MET GUIDANCE. AFTER TAKING A LOOK AT LOW LEVEL TEMPS FORECASTED OVER THE AREA DURING THIS TIME AND COMPARING THEM WITH LOCAL CLIMATOLOGY...THIS UPWARDS ADJUSTMENT MADE SENSE. HIGHS WILL BE A TAD WARMER ON SUNDAY...BUT STILL SLIGHTLY COOLER THAN THOSE FROM RECENT DAYS. LOOK FOR LOWS SATURDAY NIGHT TO FALL INTO THE LOW AND MIDDLE 60S...AND LOWS SUNDAY NIGHT TO SLIP INTO THE MID 60S AND LOWER 70S. UNFORTUNATELY...JUST AS QUICK AS THIS DRIER AIR CAME...THE AIRMASS WILL MODERATE UP THROUGH THE REMAINDER OF THE FORECAST PERIOD. THIS BASICALLY EQUATES TO A RETURN TO WHAT`S BEEN THE NORM FOR SUMMER ACROSS THE CWA...HOT AND HUMID CONDITIONS WITH ISOLATED TO SCATTERED SHOWERS AND STORMS EACH AFTERNOON...LINGERING INTO THE EARLY EVENING HOURS. MODELS DO INDICATE A WEAK BOUNDARY TRYING TO SNEAK INTO THE CWA AND MEANDERING ABOUT ACROSS THE FORECAST AREA THROUGH MID-WEEK. IF THIS PANS OUT...IT COULD ENHANCE RAIN CHANCES DURING THE LATTER HALF OF THE FORECAST PERIOD...AND COULD RESULT IN A COMPLEX OR TWO OF SHOWERS AND STORMS TRAVERSING THE REGION UNDER NORTHWEST FLOW ALOFT. /19/ && .AVIATION...GREATEST AVIATION CONCERN IS THE ONGOING MVFR AND IFR CONDS ACRS KGWO TO KGTR DUE TO TSRA/LOW CIGS. XPCT CONDS TO IMPROVE BRIEFLY AT KGTR BY 1530Z WITH ADDITIONAL SCT TSRA THROUGH LATE MRNG THRU AFTN. FOR CNTRL AND SRN TAF SITES...IT WILL BE MORE TRICKY AS FAR AS TIMING. SCT TSRA XPCTED TO DVLP ACROSS REGION LATE MRNG AND PERSIST THROUGH EVENING AS MID LVL DISTURBANCE MOVES THROUGH. CNTRL AND SRN SITES SHOULD HAVE VFR PREVAIL BUT INTERMITTENT MVFR/IFR CONDS PSBL THIS AFTN. LOW CIGS/BR OVRNGT SHOULD RESULT IN MIX OF MVFR/VFR. SLY SFC WINDS WILL BE 6-12 KT WITH SOME HIGHER GUSTS THIS AFTN. SOME GUSTS TO 20-30 KT PSBL INVOF STRONGER TSRA. STORM TOPS TO FL450. /ALLEN/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 92 74 91 69 / 57 42 41 18 MERIDIAN 91 72 92 68 / 58 41 52 30 VICKSBURG 93 74 91 66 / 49 39 34 15 HATTIESBURG 92 75 93 73 / 71 20 54 28 NATCHEZ 91 75 91 70 / 61 29 42 17 GREENVILLE 95 75 91 66 / 38 48 20 9 GREENWOOD 94 74 90 65 / 66 45 22 10 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ BB/ALLEN/CME/19
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
915 PM MDT FRI AUG 10 2012 .DISCUSSION... UPDATE FORTHCOMING. HAVE LOWERED POPS ACROSS THE AREA TO BETTER REFLECT ONGOING CONDITIONS. RUC AND GFS MODELS CONTINUE TO INDICATE SCATTERED SHOWERS AND THUNDERSTORMS A POSSIBILITY ACROSS THE AREA AFTER MIDNIGHT. RADAR RETURNS INDICATE SCATTERED THUNDERSTORMS MOVING ACROSS SOUTHWEST MONTANA AT THIS TIME. EMANUEL && .AVIATION... UPDATED 2345Z. A DISTURBANCE ALOFT WILL CONTINUE TO TRACK ACROSS THE AREA OVERNIGHT. SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH 06Z AND THEN BECOME ISOLATED. CONVECTIVE ACTIVITY SHOULD END BY 10Z. HIGH PRESSURE ALOFT WILL BUILD BACK OVER THE AREA WITH SKIES CLEARING AFTER 12Z. VFR CONDITIONS PREVAIL WITH BRIEF MVFR CONDITIONS IN THE VICINITY OF THUNDERSTORMS. GUSTY ERRATIC WINDS WILL ALSO OCCUR IN THE VICINITY OF THUNDERSTORMS. && .PREV DISCUSSION...ISSUED 245 PM MDT FRI AUG 10 2012 TONIGHT THROUGH SUNDAY...SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE CENTRAL AND SOUTHERN SECTIONS OF THE REGION THROUGH THE EVENING HOURS...THUS POPS HAVE BEEN INCREASED IN THIS REGION. FURTHER NORTH...A PASSING THUNDERSTORM IS POSSIBLE. SOME STORMS OVER CENTRAL MONTANA COULD PRODUCE GUSTY WINDS THIS EVENING. EXPECT MOST OF THE THUNDERSTORM ACTIVITY TO TAPPER OFF BY EARLY SATURDAY MORNING...THEN A MOSTLY DRY AND QUIET WEEKEND IS EXPECTED FOR MUCH OF THE AREA. THE ONLY EXCEPTION IS A SMALL CHANCE FOR AN ISOLATED THUNDERSTORM ON SUNDAY AFTERNOON UP IN THE CUT BANK AREA...AS A WEAK UPPER LEVEL DISTURBANCE MOVES SOUTHWARD INTO THE REGION. SUMMER LIKE TEMPERATURES WILL CONTINUE OVER THE REGION...WITH MOST LOCATIONS RUNNING ABOUT 5 DEGREES ABOVE NORMAL FOR AFTERNOON HIGH TEMPERATURES ON SATURDAY AND SUNDAY. BRUSDA SUNDAY NIGHT THROUGH FRIDAY...THE UPPER LEVEL RIDGE OVER THE ZONES WILL BE FLATTENED SUNDAY NIGHT AS A SHORTWAVE MOVES THROUGH THE REGION. MID LEVEL MOISTURE WILL BE PRESENT AND SOME CONVECTION WILL CONTINUE THROUGH THE EVENING HOURS. THE SHORTWAVE WILL MOVE EAST OF THE ZONES AND HIGH PRESSURE WILL AGAIN DOMINATE ON MONDAY BUT THE NEXT LOW PRESSURE TROF WILL ALREADY BE MOVING OVER THE WEST COAST. THIS SHORTWAVE WILL MOVE ACROSS THE REGION TUESDAY AND THE ASSOCIATED COLD FRONT WILL BRING MUCH COOLER TEMPS INTO THE AREA. THE ECMWF IS CONSIDERABLY COOLER THAN THE GFS UNTIL MATCHING UP AGAIN 12Z SAT. THE ECMWF TENDS TO HANDLE SIGNIFICANT CHANGES IN TEMPERATURES BETTER THAN OTHER MODELS...SO HAVE TRENDED TEMPERATURES COOLER THAN MOST MODELS...BUT NOT AS COOL AS THE ECMWF FOR NOW. WILL CONTINUE TO MONITOR THE PROGRESS OF THIS SYSTEM. AN UPPER LEVEL HIGH PRESSURE RIDGE WILL BE OVER THE WEST COAST BY WEDNESDAY AND HEIGHTS OVER THE ZONES WILL BE REBUILDING. THIS HIGH PRESSURE RIDGE WILL CONTINUE TO BUILD THROUGH FRIDAY AND THE AIRMASS WILL REMAIN WARM AND DRY. TEMPS WILL BEGIN THE PERIOD WELL ABOVE NORMALS...DROP TO BELOW NORMALS TUESDAY AND WEDNESDAY...THEN BEGIN TO TREND UPWARDS AGAIN THROUGH FRIDAY. ZELZER/COULSTON && .PRELIMINARY POINT TEMPS/POPS... GTF 57 89 55 89 / 60 10 0 10 CTB 52 83 51 83 / 30 10 0 20 HLN 57 90 55 90 / 60 10 0 10 BZN 50 88 48 91 / 70 20 10 10 WEY 41 77 38 81 / 40 20 10 0 DLN 50 85 48 88 / 30 10 0 0 HVR 60 90 54 87 / 50 10 0 10 LWT 54 84 52 83 / 80 20 10 10 && .TFX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING BROADWATER... CASCADE...CENTRAL AND SOUTHERN LEWIS AND CLARK...CHOUTEAU... EASTERN TETON...FERGUS...JEFFERSON...JUDITH BASIN...NORTHERN ROCKY MOUNTAIN FRONT...SOUTHERN ROCKY MOUNTAIN FRONT...MEAGHER...BEAVERHEAD AND MADISON. RED FLAG WARNING UNTIL MIDNIGHT MDT THIS EVENING GALLATIN... && $$ WEATHER.GOV/GREATFALLS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
918 AM MDT THU AUG 9 2012 .SHORT TERM...VALID FOR TDY AND FRI... MINOR UPDATE TO THE FORECAST THIS MORNING TO ADD ISOLATED POPS FROM BAKER SOUTHWEST TO SHERIDAN. WEAK UPPER WAVE WAS DRAGGING A SURFACE TROUGH ACROSS THIS AREA AND IS GENERATING ISOLATED PRECIPITATION. A FEW LIGHTNING STRIKES HAVE BEEN OBSERVERED JUST NORTH OF WHEATLAND COUNTY AS WEAK INSTABILITY IS DEVELOPING. INCREASED CLOUD COVERAGE OVER THE EASTERN ZONES THIS MORNING BUT SKY`S SHOULD CLEAR BY EARLY THIS AFTERNOON BEHIND THE UPPER WAVE. RICHMOND PREVIOUS DISCUSSION... EARLY MORNING RAP MODEL DATA AND WATER VAPOR IMAGERY SHOWS THE UPPER LEVEL RIDGE IS SLOWLY STARTING TO BREAK DOWN ALREADY. EVEN THOUGH THE RIDGE WILL BECOME FLATTER TODAY...CONDITIONS WILL STILL BE HOT AND DRY ACROSS THE REGION. THERE IS A SLIGHT CHANCE FOR AN ISOLATED SHOWER OR THUNDERSTORM...MAINLY OVER WESTERN ZONES...AS AN IMPULSE OF ENERGY MAKES IT OVER THE AREA THIS AFTERNOON. THERE IS A LITTLE INSTABILITY OVER MOUNTAINOUS REGIONS IN THE WESTERN ZONES...BUT NOT SURE IF IT WILL BE REALIZED DUE TO STRONG CAP AT 850 AND 700 MB. FOR FRIDAY...THE FOCUS TURNS TO THE POTENTIAL FOR WIDESPREAD SHOWERS AND THUNDERSTORMS OVER MOST OF THE AREA. MODELS ARE IN GOOD AGREEMENT IN PROGGING A SERIES OF VORTICITY POCKETS OVER SOUTH CENTRAL MONTANA BY FRIDAY AFTERNOON. THE TIMING IS SLIGHTLY DIFFERENT BETWEEN THE NAM AND GFS SOLUTIONS...WITH THE GFS LINGERING A LITTLE BIT LONGER BEFORE EXITING THE CWA TO THE EAST. 500 TO 300 MB Q VECTOR MODEL FIELDS SHOW MAXIMIUM CONVERGENCE JUST NORTH OF THE CWA...WHICH WILL HELP TO DEVELOP A LEE SIDE TROUGH AT THE SURFACE. ..AND WILL SERVE AS THE FOCUS FOR MOST OF THE PRECIPITATION ACTIVITY. MIN ADDITION...A WIND SPEED MAXIMA AT 850 WILL ATTEMPT TO SUPPLY MOISTURE TO THE AREA. THE MAIN MOISTURE AXIS IS IN WESTERN SOUTH DAKOTA...BUT THE BREADTH OF THE LOW LEVEL JET SHOULD BE WIDE ENOUGH TO HELP SUPPORT THUNDERSTORM GROWTH OVER EASTERN ZONES BY FRIDAY NIGHT. AS FAR AS INSTABILITY IS CONCERNED...LIFTED INDICES APPROACH -5 C OVER SOUTHEAST MONTANA...WHICH COINCIDES WITH CAPE VALUES APPROACHING 1000 J/KG AT MODEL SOUNDINGS FOR KBHK. AT CURRENT TIME SHEAR PROFILES DO NOT APPEAR STRONG ENOUGH TO SUPPORT WIDESPREAD SEVERE STORMS...BUT THAT MAY CHANGE AS THE SURFACE TROUGH SETS UP. MAIN CONCERNS WOULD BE FOR LARGE HAIL AND STRONG WINDS. SINGER .LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED... MODELS TRENDING A BIT SLOWER WITH DEPARTURE OF SECONDARY SHORTWAVE ON SATURDAY...THUS LOOKS LIKE A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS ESPECIALLY IN OUR EAST ON THIS DAY. WITH PRECIPITABLE WATERS ON THE ORDER OF 1.2 INCHES AND LOW LCL HEIGHTS FROM KMLS-K4BQ EASTWARD THINK SOME HEAVY RAIN IS A POSSIBILITY. THIS ENERGY WILL EXIT TO THE EAST BY SATURDAY EVENING. HAVE TAPERED BACK EXPECTED HIGHS A BIT IN OUR EAST. CHANCES OF PCPN NOT GREAT IN THE SUNDAY-TUESDAY TIME PERIOD AS UPPER LEVEL RIDGE AND HIGH HEIGHTS WILL BE DOMINANT...BUT COULD BE SOME MAINLY DIURNAL WEAK CONVECTION OVER OUR MTNS AND PERHAPS AT TIMES IN OUR EAST WHERE LOW LEVEL BOUNDARY AND EAST WINDS WILL LINGER. TEMPERATURES WILL REMAIN ABOVE NORMAL WITH HIGHS MOSTLY IN THE UPPER 80S TO MID 90S. TUESDAY MAY BE THE WARMEST DAY GIVEN POTENTIAL FOR PREFRONTAL WARMING UNDER INCREASED SW FLOW ALOFT. MODELS IN GOOD OVERALL AGREEMENT IN SHOWING A COOL DOWN BY WEDNESDAY AND THURSDAY OF NEXT WEEK...THOUGH WITH DIFFERENCES IN THE DETAILS AS SHARP UPPER TROF SLIDES OUT OF THE NORTHWEST. MODEL CONSENSUS SUGGESTS COOL ADVECTION AND NORTH WINDS BEGINNING WEDNESDAY AND A MUCH COOLER DAY BY THURSDAY...WITH INCREASED CHANCES OF PRECIPITATION. WITH SOME CONFIDENCE HAVE RAISED POPS TO ABOVE CLIMATOLOGY...AND EXPECT TEMPS TO FALL BELOW NORMAL BY THURSDAY. JKL && .AVIATION... MOSTLY CLOUDY SKIES WILL GIVE WAY TO PARTLY CLOUDY SKIES EAST OF A KSHR-KMLS LINE TODAY. WEST OF THIS LINE...EXPECT PARTLY TO MOSTLY SUNNY SKIES. AN ISOLATED THUNDERSTORM WILL BE POSSIBLE...MAINLY OVER THE MOUNTAINS AND ADJACENT FOOTHILLS. GUSTY ERRATIC WINDS AND MVFR CONDITIONS WILL BE POSSIBLE WITH ANY THUNDERSTORM. WIDESPREAD AREAS OF SMOKE WILL EXIST AS WELL...BUT OVERALL...VFR CONDITIONS WILL PREVAIL TODAY. HOOLEY && .PRELIMINARY POINT TEMP/POPS... TDY FRI SAT SUN MON TUE WED ------------------------------------------------------- BIL 098 062/091 063/088 061/093 062/093 063/091 060/083 2/T 23/T 42/T 11/B 21/B 11/B 22/T LVM 096 054/088 055/090 052/093 052/092 053/087 051/083 3/T 34/T 41/B 11/B 21/B 12/T 23/T HDN 101 063/094 063/091 061/095 061/096 063/094 058/085 2/T 23/T 42/T 11/U 21/B 11/B 22/T MLS 099 065/093 066/088 062/093 064/095 064/092 062/086 2/T 23/T 43/T 12/T 22/T 11/B 22/T 4BQ 098 064/092 064/088 061/093 062/094 065/093 060/087 2/T 23/T 53/T 11/U 12/T 11/B 22/T BHK 092 062/089 063/084 060/088 061/090 064/090 061/085 2/T 23/T 54/T 22/T 22/T 22/T 22/T SHR 097 059/090 060/087 056/091 058/094 059/093 055/086 2/T 23/T 42/T 11/B 12/T 11/B 22/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS BILLINGS MT
325 AM MDT THU AUG 9 2012 .SHORT TERM...VALID FOR TDY AND FRI... EARLY MORNING RAP MODEL DATA AND WATER VAPOR IMAGERY SHOWS THE UPPER LEVEL RIDGE IS SLOWLY STARTING TO BREAK DOWN ALREADY. EVEN THOUGH THE RIDGE WILL BECOME FLATTER TODAY...CONDITIONS WILL STILL BE HOT AND DRY ACROSS THE REGION. THERE IS A SLIGHT CHANCE FOR AN ISOLATED SHOWER OR THUNDERSTORM...MAINLY OVER WESTERN ZONES...AS AN IMPULSE OF ENERGY MAKES IT OVER THE AREA THIS AFTERNOON. THERE IS A LITTLE INSTABILITY OVER MOUNTAINOUS REGIONS IN THE WESTERN ZONES...BUT NOT SURE IF IT WILL BE REALIZED DUE TO STRONG CAP AT 850 AND 700 MB. FOR FRIDAY...THE FOCUS TURNS TO THE POTENTIAL FOR WIDESPREAD SHOWERS AND THUNDERSTORMS OVER MOST OF THE AREA. MODELS ARE IN GOOD AGREEMENT IN PROGGING A SERIES OF VORTICITY POCKETS OVER SOUTH CENTRAL MONTANA BY FRIDAY AFTERNOON. THE TIMING IS SLIGHTLY DIFFERENT BETWEEN THE NAM AND GFS SOLUTIONS...WITH THE GFS LINGERING A LITTLE BIT LONGER BEFORE EXITING THE CWA TO THE EAST. 500 TO 300 MB Q VECTOR MODEL FIELDS SHOW MAXIMUM CONVERGENCE JUST NORTH OF THE CWA...WHICH WILL HELP TO DEVELOP A LEE SIDE TROUGH AT THE SURFACE...AND WILL SERVE AS THE FOCUS FOR MOST OF THE PRECIPITATION ACTIVITY. IN ADDITION...A WIND SPEED MAXIMA AT 850 WILL ATTEMPT TO SUPPLY MOISTURE TO THE AREA. THE MAIN MOISTURE AXIS IS IN WESTERN SOUTH DAKOTA...BUT THE BREADTH OF THE LOW LEVEL JET SHOULD BE WIDE ENOUGH TO HELP SUPPORT THUNDERSTORM GROWTH OVER EASTERN ZONES BY FRIDAY NIGHT. AS FAR AS INSTABILITY IS CONCERNED...LIFTED INDICES APPROACH -5 C OVER SOUTHEAST MONTANA...WHICH COINCIDES WITH CAPE VALUES APPROACHING 1000 J/KG AT MODEL SOUNDINGS FOR KBHK. AT CURRENT TIME SHEAR PROFILES DO NOT APPEAR STRONG ENOUGH TO SUPPORT WIDESPREAD SEVERE STORMS...BUT THAT MAY CHANGE AS THE SURFACE TROUGH SETS UP. MAIN CONCERNS WOULD BE FOR LARGE HAIL AND STRONG WINDS. SINGER .LONG TERM...VALID FOR SAT...SUN...MON...TUE...WED... MODELS TRENDING A BIT SLOWER WITH DEPARTURE OF SECONDARY SHORTWAVE ON SATURDAY...THUS LOOKS LIKE A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS ESPECIALLY IN OUR EAST ON THIS DAY. WITH PRECIPITABLE WATERS ON THE ORDER OF 1.2 INCHES AND LOW LCL HEIGHTS FROM KMLS-K4BQ EASTWARD THINK SOME HEAVY RAIN IS A POSSIBILITY. THIS ENERGY WILL EXIT TO THE EAST BY SATURDAY EVENING. HAVE TAPERED BACK EXPECTED HIGHS A BIT IN OUR EAST. CHANCES OF PCPN NOT GREAT IN THE SUNDAY-TUESDAY TIME PERIOD AS UPPER LEVEL RIDGE AND HIGH HEIGHTS WILL BE DOMINANT...BUT COULD BE SOME MAINLY DIURNAL WEAK CONVECTION OVER OUR MTNS AND PERHAPS AT TIMES IN OUR EAST WHERE LOW LEVEL BOUNDARY AND EAST WINDS WILL LINGER. TEMPERATURES WILL REMAIN ABOVE NORMAL WITH HIGHS MOSTLY IN THE UPPER 80S TO MID 90S. TUESDAY MAY BE THE WARMEST DAY GIVEN POTENTIAL FOR PREFRONTAL WARMING UNDER INCREASED SW FLOW ALOFT. MODELS IN GOOD OVERALL AGREEMENT IN SHOWING A COOL DOWN BY WEDNESDAY AND THURSDAY OF NEXT WEEK...THOUGH WITH DIFFERENCES IN THE DETAILS AS SHARP UPPER TROF SLIDES OUT OF THE NORTHWEST. MODEL CONSENSUS SUGGESTS COOL ADVECTION AND NORTH WINDS BEGINNING WEDNESDAY AND A MUCH COOLER DAY BY THURSDAY...WITH INCREASED CHANCES OF PRECIPITATION. WITH SOME CONFIDENCE HAVE RAISED POPS TO ABOVE CLIMATOLOGY...AND EXPECT TEMPS TO FALL BELOW NORMAL BY THURSDAY. JKL && .AVIATION... VFR CONDITIONS WILL PREVAIL ACROSS THE REGION TODAY...WITH SOME HIGH-BASED THUNDERSTORM ACTIVITY EXPECTED ESPECIALLY ALONG THE MOUNTAINS AND FOOTHILLS THIS AFTERNOON AND EVENING. ERRATIC WIND GUSTS ARE POSSIBLE NEAR ANY OF THESE STORMS. A WEAK COLD FRONT WILL BRING A SHIFT TO NORTH OR NORTHEAST WINDS TODAY...EXCEPT IN FAR EASTERN PARTS NEAR KMLS AND KBHK WHERE EASTERLY WINDS WILL PERSIST. JKL && .PRELIMINARY POINT TEMP/POPS... TDY FRI SAT SUN MON TUE WED ------------------------------------------------------- BIL 097 063/092 063/088 060/093 061/093 062/091 059/084 2/T 23/T 41/B 11/B 21/B 12/T 22/T LVM 095 055/089 055/086 052/089 052/088 053/087 051/081 3/T 34/T 41/B 12/T 22/T 22/T 22/T HDN 100 064/095 063/091 061/095 061/096 063/094 058/086 2/T 23/T 42/T 12/T 22/T 12/T 22/T MLS 098 066/094 066/089 062/093 064/096 064/092 061/083 2/T 23/T 42/T 12/T 22/T 22/T 22/T 4BQ 097 065/093 064/089 061/093 062/094 065/093 058/083 2/T 23/T 42/T 12/T 22/T 22/T 22/T BHK 091 063/090 063/086 060/088 061/090 064/089 060/080 1/B 23/T 52/T 22/T 22/T 22/T 22/T SHR 096 060/091 060/087 056/091 058/094 059/090 055/082 2/T 23/T 42/T 12/T 22/T 11/B 22/T && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...NONE. WY...NONE. && $$ WEATHER.GOV/BILLINGS
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
305 PM CDT THU AUG 9 2012 .DISCUSSION... TEMPERATURES WILL PROVIDE THE PRIMARY FORECAST CHALLENGES THROUGH FRIDAY NIGHT...THEN ATTENTION SHIFTS MORE TOWARD PRECIPITATION CHANCES OVER THE WEEKEND. MAIN FEATURES FROM THE 12Z UPPER AIR CHARTS THIS MORNING SHOWED THE FOLLOWING. AT 300 MB...JETSTREAM CURVED NORTHEAST ACROSS THE PACIFIC NORTHWEST INTO THE NORTHERN PLAINS...THEN TURNED SOUTHEAST INTO THE OHIO VALLEY. A JET MAX OF AROUND 100 KNOTS WAS NOTED OVER MINNESOTA. AT 500 MB...A RATHER IMPRESSIVE CLOSED LOW WAS OVER NORTHEAST MINNESOTA WITH 12 HOUR HEIGHT FALLS OF 70 METERS NOTED AT KINL. THE CENTER OF A MID LEVEL RIDGE WAS OVER THE FOUR CORNERS REGION. COOLER AIR WAS PUSHING DOWN FROM MINNESOTA AND THE EASTERN DAKOTAS AT 700 MB AND 850 MB. SURFACE ANALYSIS EARLY THIS AFTERNOON INDICATED A RIDGE OF COOL HIGH PRESSURE EXTENDING FROM ONTARIO AND MANITOBA DOWN INTO THE NORTHERN AND WESTERN PLAINS. WINDS WERE MAINLY FROM THE NORTH OVER THE LOCAL AREA. THAT SURFACE RIDGE WILL BUILD EASTWARD ACROSS THE FORECAST AREA TONIGHT THROUGH FRIDAY NIGHT...WITH SEASONABLE TEMPERATURES AND DRY CONDITIONS. EXPECT SOME PATCHY FOG TONIGHT AS WINDS DECREASE... ESPECIALLY IN PARTS OF OUR CENTRAL AND EASTERN ZONES WHERE SPOTTY RAIN FELL YESTERDAY AND TUESDAY. EXPECT THAT TO BURN OFF QUICKLY FRIDAY...IF IT DEVELOPS...WITH SCATTERED CUMULUS MOST AREAS BY THE AFTERNOON. HIGHS FRIDAY WILL BE IN THE 80S...CLOSE TO NAM MOS. RETURN FLOW STRENGTHENS LATE FRIDAY NIGHT INTO SATURDAY AND MODELS ARE IN GENERAL AGREEMENT WITH LARGE SCALE PATTERN. THEY SHOW SOME 850-700 MB THETA E ADVECTION SPREADING FROM WEST TO EAST ON SATURDAY. LARGE SCALE FORCING SEEMS WEAK AT BEST...SO KEPT POPS ONLY AT 20 PERCENT AND TRIED TO CONFINE THOSE TO NORTHEAST NEBRASKA SATURDAY. A MODEST SHORTWAVE TROUGH DOES MOVE ACROSS THE PLAINS FOR SATURDAY NIGHT/EARLY SUNDAY...AND THIS IS PROBABLY OUR BEST CHANCE FOR THUNDERSTORMS. THE 12Z GFS SEEMED WAY TOO GENEROUS WITH QPF AND ITS OUTPUT WAS GENERALLY NOT USED. FAVORED A BLEND OF THE NAM AND ECMWF FOR NOW...BUT SHOULD BE ABLE TO ADJUST THINGS MORE AS WE GET CLOSER WITH 4 KM NAM AND HRRR MODELS. LINGERED SOME LOW POPS INTO SUNDAY BASED ON CURRENT MODEL TIMING OF FORCING. OTHERWISE...LOOK FOR DEAMPLIFICATION OF THE 500 MB PATTERN THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK AS RIDGE SHIFTS FROM THE FOUR CORNERS REGION TO THE SOUTHERN PLAINS. AS HEIGHTS INCREASE BY MID WEEK...HIGHS IN THE 90S WILL BECOME COMMON AGAIN. MILLER && .AVIATION... 18Z TAFS FOR KOMA...KLNK AND KOFK. THE PRIMARY CONCERN FOR THIS TAF PACKAGE ARE THE NORTHWEST THRU NORTHEAST WINDS. A WEATHER SYSTEM OVER THE UPPER GREAT LAKES INTO MINNESOTA WILL DROP SOUTHEAST INTO THE LOWER GREAT LAKES AND OHIO VALLEY. SOME STRONGER WINDS ALOFT WILL MIX DOWN THIS AFTERNOON. THE TRACK OF THIS SYSTEM SHOULD KEEP THE ACTIVE WEATHER TO THE EAST OF THE TAF SITES. SURFACE WINDS WILL RANGE FROM 10 TO 18KTS SUSTAINED WITH GUSTS TO 22KTS. CUMULUS THIS AFTERNOON SHOULD GIVE WAY TO DECREASING CLOUDS AFTER SUNSET. THE SURFACE WINDS WILL DIMINISH TO 5KTS OR LESS THIS EVENING AS SURFACE HIGH PRESSURE BUILDS IN. ZAPOTOCNY && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
138 PM EDT THU AUG 9 2012 .SYNOPSIS... WEAK SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TODAY. A STRONG SURFACE COLD FRONT WILL APPROACH OUR REGION FROM THE NORTHWEST FRIDAY AND CROSS CENTRAL NC ON SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1000 AM THURSDAY... A SMALL AREA OF STRATUS OVER WILSON...NASH AND EDGECOMBE COUNTIES IS ERODING AND DRIFTING NORTHEAST AND WILL GIVE WAY TO MOSTLY CLEAR SKIES OVER THE COASTAL PLAIN THIS MORNING. HOWEVER...SOME THIN HIGH CLOUDS OUT AHEAD OF CONVECTION OVER NORTHERN MS/AL WILL OVERSPREAD THE AREA FROM THE WEST...AND SHOULD BECOME THICKER OVER THE WESTERN PIEDMONT LATER TODAY AS THE SHORTWAVE RESPONSIBLE FOR THE CONVECTION SWINGS INTO THE SOUTHEAST US. TEMPS WILL BE MOSTLY UNAFFECTED BY THE CLOUDS...HOWEVER. THE 12Z KGSO RAOB CAME IN WITH A LOW LEVEL THICKNESS OF 1414M... A GOOD 5M HIGHER THAN FORECAST. ADDING A COUPLE DEGREES ONTO HIGHS DERIVED FROM 1414M YIELDS 90-93...WHICH IS IN LINE WITH STATISTICAL GUIDANCE AND THE CURRENT FORECAST. MODIFIED 12Z RAOBS AND MODEL FORECASTS SHOW 1500-2000 J/KG OF MLCAPE THIS AFTERNOON...GREATEST FROM THE COASTAL PLAIN TO THE SOUTHERN PIEDMONT. WEAK LOW LEVEL FORCING...ALONG WITH MUCH DRIER MID LEVEL AIR THAN THE PAST FEW DAYS...SHOULD LIMIT COVERAGE OF CONVECTION TO MOSTLY ISOLATED STORMS. THERE IS A SMALL HINT OF A WEAK SURFACE OVER THE WESTERN PIEDMONT...AND THE MORNING RUNS OF THE HRRR HAS BEEN CONSISTENTLY SHOWING CONVECTION INVITATION FROM ANSON COUNTY TO RANDOLPH COUNTY JUST AFTER 18Z. ANY STRONGER STORMS THAT DEVELOP WILL HAVE PLENTY OF DRY AIR TO ENTRAIN...AS WELL AS A WETBULB FREEZING LEVEL BELOW 10K FT...SO AN ISOLATED WIND/HAIL THREAT WILL EXIST. -SMITH TONIGHT...DECENT MID LEVEL TROUGH CURRENTLY OVER THE MO/ARK OZARKS PROJECTED TO ADVANCE EWD AND WILL APPROACH OUR REGION AFTER SUNSET. THE MODELS HAVE BEEN FAIRLY CONSISTENT WITH THIS FEATURE AND CONFIDENCE INCREASING THAT WE WILL LIKELY SEE AT LEAST SCATTERED CONVECTION EITHER MOVE INTO OR DEVELOPMENT OVER THE WESTERN PIEDMONT AFTER MIDNIGHT. HAVE INCREASED POPS SLIGHTLY IN THE FAR WEST TO 40 PERCENT. IF MODEL GUIDANCE REMAINS CONSISTENT....COULD ARGUE FOR A MENTION OF LIKELY THOUGH LOW LEVEL ATMOSPHERE WILL ACHIEVE MAXIMUM STABILITY DURING THIS PERIOD. MIN TEMPS UPPER 60S TO LOWER 70S. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 315 AM THURSDAY... FRIDAY...CONVECTIVELY ACTIVE DAY POSSIBLE ACROSS CENTRAL NC THOUGH STILL SOME QUESTION AS THE AMOUNT OF INSTABILITY AND SHEAR THAT WILL BE ATTAINED. AFOREMENTIONED MID LEVEL TROUGH WILL SLOW ITS EWD ADVANCE...WAITING FOR ENERGY ROTATING AROUND THE DEEPENING UPPER LEVEL TROUGH OVER THE GREAT LAKES TO ROUND THE BASE OF THE TROUGH. THIS LEAD TROUGH WILL LIKELY MAINTAIN CONSIDERABLE CLOUDINESS IN THE MORNING ALONG WITH SCATTERED TO NUMEROUS SHOWERS AND A FEW T-STORMS. AS THE ENERGY IN THE GREAT LAKES TROUGH GETS CLOSER TO THE APPALACHIANS AND MID ATLANTIC...SHOULD SEE AN INCREASE IN THE 850-700MB WIND FIELD LEADING TO BETTER BULK SHEAR (AROUND 30 KTS) SUGGESTING BETTER POTENTIAL FOR ORGANIZED CONVECTION. DUE TO DEEP UNIDIRECTIONAL FLOW...EXPECT MAINLY MULTICELLULAR LINEAR CONVECTION WITH POTENTIAL FOR DAMAGING WIND GUSTS AND SOME HAIL. TIMING FAVORS LATE FRIDAY INTO FRIDAY EVENING...AND MAINLY ALONG AND EAST OF HIGHWAY 1 WHERE BETTER LOW LEVEL INSTABILITY WILL LIE. TEMPS FRIDAY DEPENDENT ON AMOUNT OF INSOLATION. EXPECT A PERIOD OF PARTIAL SUN IN THE AFTERNOON PRIOR TO CONVECTION BECOMING MORE ACTIVE. THICKNESSES IN THE LOWER 1420S SUPPORT MAX TEMPS IN THE 80S TO NEAR 90. FRIDAY NIGHT...EXPECT ACTIVE CONVECTION TO PERSIST THROUGH THE NIGHT AS TROUGH BECOMES ELONGATED DUE TO APPROACH OF GREAT LAKES SYSTEM. DEEPENING SW FLOW WILL LIKELY CAUSE CONVECTIVE BANDS TO TRAIN NEWD. THUS...SHOULD SEE WEATHER SCENARIO TRANSITION FROM A SEVERE WEATHER THREAT IN THE EARLY EVENING TO A HEAVY RAIN THREAT THAT WILL PERSIST INTO EARLY SATURDAY. WILL CONTINUE LIKELY POPS FOR NOW. MIN TEMPS UPPER 60S TO LOWER 70S. -WSS SATURDAY AND SATURDAY NIGHT: THE SURFACE COLD FRONT IS EXPECTED TO SLOWLY MOVE ACROSS CENTRAL NC ON SATURDAY... BEFORE STALLING AND DISSIPATING ACROSS THE COASTAL PLAIN OR JUST TO THE SOUTH AND EAST OF THE AREA SATURDAY NIGHT INTO SUNDAY. HAVE FOLLOWED CLOSER TO A BLEND OF THE GFS AND ECWMF WRT THE FRONTAL TIMING AS HPC CONTINUES TO NOTE THE NAM APPEARS TO BE A SLOW OUTLIER. THIS WILL LEAD TO ANOTHER GOOD CHANCE OF SHOWERS AND STORMS FOR AT LEAST EASTERN AND SOUTH/SOUTHEASTERN PORTIONS OF THE AREA. HAVE INCREASED POPS ACROSS THE EASTERN AND SOUTH/SOUTHEASTERN PORTIONS OF THE AREA FOR SATURDAY... GIVEN A BIT SLOWER TIMING OF THE FRONT. THIS YIELDS LIKELY POPS EAST/SOUTHEAST TO SLIGHT CHANCE NORTHWEST. WITH THE SURFACE FRONT DRAPED ACROSS THE AREA A GOOD PART OF THE DAY THIS WILL CREATE A TRICKY HIGH TEMP FORECAST ALONG WITH HOW MUCH INSTABILITY WILL BE PRESENT (HOW MUCH HEATING WILL WE BE ABLE TO REALIZE WITH THE PARTLY SUNNY TO MOSTLY CLOUDY SKIES) AND RESULTANT SEVERE STORM CHANCES. THE GFS IS SHOWING 1000 TO 1500 J/KG OF MLCAPE FOR SATURDAY AFTERNOON GENERALLY ALONG AND EAST OF U.S. HIGHWAY 1. THIS COMBINED WITH CONTINUED LARGE SCALE LIFT AND DEEP LAYER SHEAR ON THE ORDER OF 30 TO 35 KTS SHOULD LEAD TO AT LEAST SOME ORGANIZED CONVECTION ACROSS EASTERN PORTIONS OF THE AREA... WITH THE MAIN SEVERE THREAT FROM DAMAGING WINDS. IN ADDITION TO THE THREAT FOR SEVERE STORMS... THE STRONGEST STORMS WILL LIKELY PRODUCE HEAVY RAIN AS PW`S ARE EXPECTED TO CONTINUE TO BE AROUND 2 INCHES ACROSS THE EAST AND SOUTH/SOUTHEAST. THIS MAY LEAD TO A FLASH FLOODING THREAT WITH THE POTENTIAL OF THE SLOW MOVING FRONT... ESPECIALLY ACROSS URBAN AREAS. WILL ADD MENTION OF SEVERE STORMS AND FLASH FLOODING TO THE HWO FOR THIS TIMEFRAME. WILL TREND POPS DOWNWARD SATURDAY NIGHT AS THE CLOSED LOW ALOFT OVER THE GREAT LAKES BEGINS TO LIFT NORTH-NORTHEASTWARD ALLOWING THE MAIN MID LEVEL TROUGH AXIS TO SWING THROUGH THE AREA. THIS WILL YIELD NO POPS NW TO SLIGHT CHANCE/CHANCE EAST/SOUTHEAST. AS MENTIONED ABOVE... HIGH TEMPS WILL BE TRICKY FOR SATURDAY. FOR NOW WILL KEEP HIGHS IN THE MID TO UPPER 80S ACROSS THE AREA. LOW TEMPS ON SUNDAY MORNING ARE EXPECTED TO RANGE FROM THE MID 60S NW TO AROUND 70 SE. -BSD && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 315 AM THURSDAY... THE COLD FRONT MENTIONED IN THE SHORT TERM DISCUSSION ABOVE IS EXPECTED TO CONTINUE TO DISSIPATE/WASH OUT ON SUNDAY JUST TO THE EAST AND SOUTHEAST OF THE AREA AS THE MID/UPPER FLOW BECOMES MORE ZONAL IN THE WAKE OF THE DEPARTED MID/UPPER TROUGH ALOFT. THIS WILL RESULTED IN GENERALLY DRY CONDITIONS... WITH ONLY SLIGHT CHANCES FOR SHOWERS AND STORMS ON SUNDAY AND MONDAY. UNCERTAINTY GROWS WRT THE STRENGTH AND TIMING OF A MUCH WEAKER S/W TROUGH ALOFT AND MOISTURE RETURN FOR MONDAY NIGHT THROUGH TUESDAY NIGHT. FOR NOW WILL SHOW A SLIGHT CHANCE OF DIURNAL SHOWERS AND STORMS FOR THIS TIMEFRAME. THE WEAK S/W TROUGH ALOFT IS EXPECTED TO BE EAST OF THE AREA BY WEDNESDAY WITH RIDING ALOFT BUILDING BACK INTO THE AREA... YIELDING LESS OF A CHANCE OF AFTERNOON AND EVENING STORMS. TEMPS DURING THE PERIOD ARE EXPECTED TO BE IN THE MID TO UPPER 80S... WITH PERHAPS A RETURN TO SOME LOCATIONS REACHING THE LOWER 90S AGAIN BY EARLY TO MID NEXT WEEK. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 135 PM THURSDAY... THIS MORNING`S IFR/LIFR CONDITIONS HAVE DISSIPATED. SCATTERED CLOUDS BASED BELOW 3 THOUSAND FT AGL DO PERSIST... BUT THIS WILL CONTINUE TO LIFT AND DISSIPATE. CONVECTIVE CLOUDS WILL DEVELOP AND PERSIST ALONG WITH HIGH THIN CLOUDS... BUT VFR CONDITIONS WILL HOLD FOR THE REST OF THIS AFTERNOON... WITH A LIGHT WIND MAINLY FROM THE S OR SW. AFTER 22Z... THE APPROACH OF A POTENT MID LEVEL LOW PRESSURE TROUGH WILL BRING INCREASING COVERAGE OF SHOWERS AND STORMS FROM WEST TO EAST... LIKELY AFFECTING INT/GSO AFTER 23Z... RDU AFTER 01Z... AND RWI/FAY (WITH LESSER AREAL COVERAGE) AFTER 03Z. MVFR CONDITIONS ARE LIKELY IN AND NEAR STORMS WITH BRIEF GUSTY WINDS. THE PERIOD OF STORMY CONDITIONS IS LIKELY TO LAST FOR 2-4 HOURS AT ANY GIVEN FORECAST SITE. SCATTERED SHOWERS MAY PERSIST AFTER 07Z TONIGHT BUT WILL BE LOW IN COVERAGE. SCATTERED CLOUDS BASED AT 1-3 THOUSAND FT AGL ARE EXPECTED 08Z-13Z WITH MVFR VSBYS POSSIBLE. RAPIDLY INCREASING DEEP MOISTURE THROUGH THE COLUMN COMBINED WITH THE APPROACHING LOW PRESSURE TROUGH ALOFT WILL FORCE AN EARLY DEVELOPMENT OF SCATTERED TO NUMEROUS SHOWERS/STORMS BY LATE FRIDAY MORNING... AS EARLY AS 15Z. LOOKING BEYOND 18Z FRIDAY... EXPECT ONGOING NUMEROUS STORMS THROUGH THE AFTERNOON WITH A HIGH PROBABILITY OF BRIEF MVFR CIGS/VSBYS IN AND NEAR THESE STORMS. STORMS SHOULD SLOWLY WEAKEN AND BECOME SCATTERED TO ISOLATED BY LATE FRIDAY EVENING... THEN INCREASE ANEW BY LATE SATURDAY MORNING AS A COLD FRONT SLOWLY MOVES IN FROM THE WEST. MVFR CONDITIONS ARE POSSIBLE THROUGH SATURDAY NIGHT... BUT THE ARRIVAL OF DRIER AIR WILL BRING A TREND TO PREVAILING VFR CONDITIONS SUNDAY MORNING. NO SIGNIFICANT PERIODS OF ADVERSE AVIATION CONDITIONS ARE ANTICIPATED FROM MIDDAY SUNDAY THROUGH TUESDAY. -GIH && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...WSS/SMITH SHORT TERM...WSS/BSD LONG TERM...BSD AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1000 AM EDT THU AUG 9 2012 .SYNOPSIS... WEAK SURFACE HIGH PRESSURE WILL BUILD OVER THE AREA TODAY. A STRONG SURFACE COLD FRONT WILL APPROACH OUR REGION FROM THE NORTHWEST FRIDAY AND CROSS CENTRAL NC ON SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1000 AM THURSDAY... A SMALL AREA OF STRATUS OVER WILSON...NASH AND EDGECOMBE COUNTIES IS ERODING AND DRIFTING NORTHEAST AND WILL GIVE WAY TO MOSTLY CLEAR SKIES OVER THE COASTAL PLAIN THIS MORNING. HOWEVER...SOME THIN HIGH CLOUDS OUT AHEAD OF CONVECTION OVER NORTHERN MS/AL WILL OVERSPREAD THE AREA FROM THE WEST...AND SHOULD BECOME THICKER OVER THE WESTERN PIEDMONT LATER TODAY AS THE SHORTWAVE RESPONSIBLE FOR THE CONVECTION SWINGS INTO THE SOUTHEAST US. TEMPS WILL BE MOSTLY UNAFFECTED BY THE CLOUDS...HOWEVER. THE 12Z KGSO RAOB CAME IN WITH A LOW LEVEL THICKNESS OF 1414M... A GOOD 5M HIGHER THAN FORECAST. ADDING A COUPLE DEGREES ONTO HIGHS DERIVED FROM 1414M YIELDS 90-93...WHICH IS IN LINE WITH STATISTICAL GUIDANCE AND THE CURRENT FORECAST. MODIFIED 12Z RAOBS AND MODEL FORECASTS SHOW 1500-2000 J/KG OF MLCAPE THIS AFTERNOON...GREATEST FROM THE COASTAL PLAIN TO THE SOUTHERN PIEDMONT. WEAK LOW LEVEL FORCING...ALONG WITH MUCH DRIER MID LEVEL AIR THAN THE PAST FEW DAYS...SHOULD LIMIT COVERAGE OF CONVECTION TO MOSTLY ISOLATED STORMS. THERE IS A SMALL HINT OF A WEAK SURFACE OVER THE WESTERN PIEDMONT...AND THE MORNING RUNS OF THE HRRR HAS BEEN CONSISTENTLY SHOWING CONVECTION INVITATION FROM ANSON COUNTY TO RANDOLPH COUNTY JUST AFTER 18Z. ANY STRONGER STORMS THAT DEVELOP WILL HAVE PLENTY OF DRY AIR TO ENTRAIN...AS WELL AS A WETBULB FREEZING LEVEL BELOW 10K FT...SO AN ISOLATED WIND/HAIL THREAT WILL EXIST. -SMITH TONIGHT...DECENT MID LEVEL TROUGH CURRENTLY OVER THE MO/ARK OZARKS PROJECTED TO ADVANCE EWD AND WILL APPROACH OUR REGION AFTER SUNSET. THE MODELS HAVE BEEN FAIRLY CONSISTENT WITH THIS FEATURE AND CONFIDENCE INCREASING THAT WE WILL LIKELY SEE AT LEAST SCATTERED CONVECTION EITHER MOVE INTO OR DEVELOPMENT OVER THE WESTERN PIEDMONT AFTER MIDNIGHT. HAVE INCREASED POPS SLIGHTLY IN THE FAR WEST TO 40 PERCENT. IF MODEL GUIDANCE REMAINS CONSISTENT....COULD ARGUE FOR A MENTION OF LIKELY THOUGH LOW LEVEL ATMOSPHERE WILL ACHIEVE MAXIMUM STABILITY DURING THIS PERIOD. MIN TEMPS UPPER 60S TO LOWER 70S. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 315 AM THURSDAY... FRIDAY...CONVECTIVELY ACTIVE DAY POSSIBLE ACROSS CENTRAL NC THOUGH STILL SOME QUESTION AS THE AMOUNT OF INSTABILITY AND SHEAR THAT WILL BE ATTAINED. AFOREMENTIONED MID LEVEL TROUGH WILL SLOW ITS EWD ADVANCE...WAITING FOR ENERGY ROTATING AROUND THE DEEPENING UPPER LEVEL TROUGH OVER THE GREAT LAKES TO ROUND THE BASE OF THE TROUGH. THIS LEAD TROUGH WILL LIKELY MAINTAIN CONSIDERABLE CLOUDINESS IN THE MORNING ALONG WITH SCATTERED TO NUMEROUS SHOWERS AND A FEW T-STORMS. AS THE ENERGY IN THE GREAT LAKES TROUGH GETS CLOSER TO THE APPALACHIANS AND MID ATLANTIC...SHOULD SEE AN INCREASE IN THE 850-700MB WIND FIELD LEADING TO BETTER BULK SHEAR (AROUND 30 KTS) SUGGESTING BETTER POTENTIAL FOR ORGANIZED CONVECTION. DUE TO DEEP UNIDIRECTIONAL FLOW...EXPECT MAINLY MULTICELLULAR LINEAR CONVECTION WITH POTENTIAL FOR DAMAGING WIND GUSTS AND SOME HAIL. TIMING FAVORS LATE FRIDAY INTO FRIDAY EVENING...AND MAINLY ALONG AND EAST OF HIGHWAY 1 WHERE BETTER LOW LEVEL INSTABILITY WILL LIE. TEMPS FRIDAY DEPENDENT ON AMOUNT OF INSOLATION. EXPECT A PERIOD OF PARTIAL SUN IN THE AFTERNOON PRIOR TO CONVECTION BECOMING MORE ACTIVE. THICKNESSES IN THE LOWER 1420S SUPPORT MAX TEMPS IN THE 80S TO NEAR 90. FRIDAY NIGHT...EXPECT ACTIVE CONVECTION TO PERSIST THROUGH THE NIGHT AS TROUGH BECOMES ELONGATED DUE TO APPROACH OF GREAT LAKES SYSTEM. DEEPENING SW FLOW WILL LIKELY CAUSE CONVECTIVE BANDS TO TRAIN NEWD. THUS...SHOULD SEE WEATHER SCENARIO TRANSITION FROM A SEVERE WEATHER THREAT IN THE EARLY EVENING TO A HEAVY RAIN THREAT THAT WILL PERSIST INTO EARLY SATURDAY. WILL CONTINUE LIKELY POPS FOR NOW. MIN TEMPS UPPER 60S TO LOWER 70S. -WSS SATURDAY AND SATURDAY NIGHT: THE SURFACE COLD FRONT IS EXPECTED TO SLOWLY MOVE ACROSS CENTRAL NC ON SATURDAY... BEFORE STALLING AND DISSIPATING ACROSS THE COASTAL PLAIN OR JUST TO THE SOUTH AND EAST OF THE AREA SATURDAY NIGHT INTO SUNDAY. HAVE FOLLOWED CLOSER TO A BLEND OF THE GFS AND ECWMF WRT THE FRONTAL TIMING AS HPC CONTINUES TO NOTE THE NAM APPEARS TO BE A SLOW OUTLIER. THIS WILL LEAD TO ANOTHER GOOD CHANCE OF SHOWERS AND STORMS FOR AT LEAST EASTERN AND SOUTH/SOUTHEASTERN PORTIONS OF THE AREA. HAVE INCREASED POPS ACROSS THE EASTERN AND SOUTH/SOUTHEASTERN PORTIONS OF THE AREA FOR SATURDAY... GIVEN A BIT SLOWER TIMING OF THE FRONT. THIS YIELDS LIKELY POPS EAST/SOUTHEAST TO SLIGHT CHANCE NORTHWEST. WITH THE SURFACE FRONT DRAPED ACROSS THE AREA A GOOD PART OF THE DAY THIS WILL CREATE A TRICKY HIGH TEMP FORECAST ALONG WITH HOW MUCH INSTABILITY WILL BE PRESENT (HOW MUCH HEATING WILL WE BE ABLE TO REALIZE WITH THE PARTLY SUNNY TO MOSTLY CLOUDY SKIES) AND RESULTANT SEVERE STORM CHANCES. THE GFS IS SHOWING 1000 TO 1500 J/KG OF MLCAPE FOR SATURDAY AFTERNOON GENERALLY ALONG AND EAST OF U.S. HIGHWAY 1. THIS COMBINED WITH CONTINUED LARGE SCALE LIFT AND DEEP LAYER SHEAR ON THE ORDER OF 30 TO 35 KTS SHOULD LEAD TO AT LEAST SOME ORGANIZED CONVECTION ACROSS EASTERN PORTIONS OF THE AREA... WITH THE MAIN SEVERE THREAT FROM DAMAGING WINDS. IN ADDITION TO THE THREAT FOR SEVERE STORMS... THE STRONGEST STORMS WILL LIKELY PRODUCE HEAVY RAIN AS PW`S ARE EXPECTED TO CONTINUE TO BE AROUND 2 INCHES ACROSS THE EAST AND SOUTH/SOUTHEAST. THIS MAY LEAD TO A FLASH FLOODING THREAT WITH THE POTENTIAL OF THE SLOW MOVING FRONT... ESPECIALLY ACROSS URBAN AREAS. WILL ADD MENTION OF SEVERE STORMS AND FLASH FLOODING TO THE HWO FOR THIS TIMEFRAME. WILL TREND POPS DOWNWARD SATURDAY NIGHT AS THE CLOSED LOW ALOFT OVER THE GREAT LAKES BEGINS TO LIFT NORTH-NORTHEASTWARD ALLOWING THE MAIN MID LEVEL TROUGH AXIS TO SWING THROUGH THE AREA. THIS WILL YIELD NO POPS NW TO SLIGHT CHANCE/CHANCE EAST/SOUTHEAST. AS MENTIONED ABOVE... HIGH TEMPS WILL BE TRICKY FOR SATURDAY. FOR NOW WILL KEEP HIGHS IN THE MID TO UPPER 80S ACROSS THE AREA. LOW TEMPS ON SUNDAY MORNING ARE EXPECTED TO RANGE FROM THE MID 60S NW TO AROUND 70 SE. -BSD && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 315 AM THURSDAY... THE COLD FRONT MENTIONED IN THE SHORT TERM DISCUSSION ABOVE IS EXPECTED TO CONTINUE TO DISSIPATE/WASH OUT ON SUNDAY JUST TO THE EAST AND SOUTHEAST OF THE AREA AS THE MID/UPPER FLOW BECOMES MORE ZONAL IN THE WAKE OF THE DEPARTED MID/UPPER TROUGH ALOFT. THIS WILL RESULTED IN GENERALLY DRY CONDITIONS... WITH ONLY SLIGHT CHANCES FOR SHOWERS AND STORMS ON SUNDAY AND MONDAY. UNCERTAINTY GROWS WRT THE STRENGTH AND TIMING OF A MUCH WEAKER S/W TROUGH ALOFT AND MOISTURE RETURN FOR MONDAY NIGHT THROUGH TUESDAY NIGHT. FOR NOW WILL SHOW A SLIGHT CHANCE OF DIURNAL SHOWERS AND STORMS FOR THIS TIMEFRAME. THE WEAK S/W TROUGH ALOFT IS EXPECTED TO BE EAST OF THE AREA BY WEDNESDAY WITH RIDING ALOFT BUILDING BACK INTO THE AREA... YIELDING LESS OF A CHANCE OF AFTERNOON AND EVENING STORMS. TEMPS DURING THE PERIOD ARE EXPECTED TO BE IN THE MID TO UPPER 80S... WITH PERHAPS A RETURN TO SOME LOCATIONS REACHING THE LOWER 90S AGAIN BY EARLY TO MID NEXT WEEK. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 730 AM THURSDAY... POCKETS OF LIFR/LIFR VISIBILITY AND CEILINGS EARLY THIS MORNING WILL DISSIPATE PRIOR TO 9 AM...LEAVING SCATTERED CLOUDS WITH BASES 1500-3000FT. BY EARLY AFTERNOON...SCATTERED CUMULUS WILL PREVAIL WITH BASES 4000-5000FT. AFTERNOON CONVECTION SHOULD BE LIMITED AS THERE IS A LACK OF A TRIGGER ALOFT AND NEAR THE SURFACE. THUS ONLY EXPECT ISOLATED CONVECTION THIS AFTERNOON THROUGH THE EARLY EVENING HOURS. A MID LEVEL TROUGH WILL APPROACH CENTRAL NC LATE TONIGHT. THIS WEATHER SYSTEM WILL TRIGGER A FEW SHOWERS AND ISOLATED T-STORMS LATE TONIGHT (AFTER 10-11 PM) OVER THE WESTERN AND SOUTHERN PIEDMONT INCLUDING IN VICINITY OF THE TRIAD TERMINALS. LATER FRIDAY AND FRIDAY...AN UPPER LEVEL TROUGH AND ATTENDANT SURFACE COLD FRONT WILL APPROACH FROM THE WEST. THIS SYSTEM INTERACTING WITH THE MOIST UNSTABLE AIR IN PLACE WILL TRIGGER/SUSTAIN SCATTERED-NUMEROUS SHOWERS AND T-STORMS FRIDAY AFTERNOON AND FRIDAY NIGHT. THIS WILL CAUSE PERIODS OF SUB VFR CONDITIONS AT ALL TAF SITES. THE STRONGER CELLS WILL HAVE THE POTENTIAL TO PRODUCE HAIL AND WIND GUSTS IN EXCESS OF 50KTS. BY SATURDAY...CONDITIONS WILL BE IMPROVING IN THE NW PIEDMONT BUT STILL EXPECT A DECENT THREAT FOR SCATTERED CONVECTION OVER THE REMAINDER OF CENTRAL NC WITH EPISODES OF SUB-VFR CEILING AND VISIBILITY DUE TO THE SHOWERS AND T-STORMS. THE SURFACE COLD FRONT SHOULD EDGE EAST OUT OF OUR AREA SATURDAY NIGHT INTO SUNDAY MORNING WITH IMPROVING AVIATION CONDITIONS PROJECTED TO LAST THROUGH MONDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...WSS/SMITH SHORT TERM...WSS/BSD LONG TERM...BSD AVIATION...WSS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
139 AM EDT THU AUG 9 2012 .SYNOPSIS... MID LEVEL WEAK SHORT WAVES MOVES FROM THE WEST OVERNIGHT. COLD FRONT AFFECTS THE AREA THURSDAY AND FRIDAY. HIGH PRESSURE BUILDS IN THIS WEEKEND WITH COOLER TEMPERATURES. && .NEAR TERM /UNTIL 8 AM THIS MORNING/... ADJUSTED SKY AND POP GRIDS PER LATEST RADAR AND SATELLITE IMAGES. ISOLATED CONVECTION CONTINUED TO FLARE ACROSS OUR SOUTHEASTERN COUNTIES TONIGHT. RADAR SHOWING STRONG PULSES WITH HIGH HAIL CORE ALOFT. COUPLE OF SEVERE STORM WARNINGS COULD BE ISSUED. ADDITIONAL CONVECTION IS NOTED OVER OH...MOVING NORTHEAST AROUND 20 KNOTS. THIS CONVECTION COULD REACH PORTIONS OF SOUTHEAST OH OVERNIGHT...CLOSER TO PERRY COUNTY OH. ADDITIONAL SHOWERS/STORMS COULD DEVELOP ALONG OUTFLOW BOUNDARIES SOUTH OF THIS CLUSTER TO AFFECT OTHER PORTIONS OF SOUTHEAST OH OVERNIGHT. MODELS SHOW SMALL VORT MAXES APPROACHING SOUTHEAST OH TONIGHT...OVER SFC DEWPOINTS IN THE MID TO UPPER 60S. PREVIOUS DISCUSSION BELOW... AT 02Z...HAVE SURFACE FRONT FROM NEAR PIT ON SW TO CMH...CVG...THEN WEST ACROSS SOUTHERN INDIANA. 00Z RAP SHOWS MAIN 500 VORT MAX CROSSING NRN WV MTNS BY 03Z...BUT HAS A WEAKENING VORT LINGERING IN NORTH CENTRAL WV THROUGH 06Z. MAY BE HELPING A FEW LINGERING STORMS CROSSING THE OHIO RIVER AT 02Z. WILL INCREASE AREAL COVERAGE OF THE FOG WHERE IT RAINS IN NRN CENTRAL WV...BUT NOT CONFIDENT ON THE EXACT INTENSITY. WILL LIMIT THE FOG IN SOUTHEAST OHIO SINCE BOUNDARY LAYER WINDS STAY UP...AND CLOUDS WITH THE NEXT 500 VORT MAX SHOULD BE APPROACHING BY THE PREDAWN HOURS. ALSO...INCREASED POPS A BIT FASTER FOR OUR SOUTHEAST OHIO COUNTIES DURING THE PREDAWN...WITH MORE SUPPORT ARRIVING...BEFORE LIFTING NE. && .SHORT TERM /8 AM THIS MORNING THROUGH FRIDAY NIGHT/... MODELS IN REASONABLE AGREEMENT WITH THE MASS FIELDS AS VIGOROUS UPPER LEVEL TROUGH AND ATTENDING COLD FRONT AFFECT OUR AREA FOR THE END OF THE WORKWEEK. IT IS SOMEWHAT OF A COMPLEX SYSTEM...AS THERE IS A LEAD UPPER TROUGH OUT AHEAD OF THE MAIN UPPER TROUGH. THIS LEAD UPPER TROUGH WILL OUTRUN THE FRONT AND MAY BRING SCATTERED SHOWERS AND THUNDERSTORMS THURSDAY NIGHT. WITHOUT A LOW LEVEL FOCUSING MECHANISM...WILL STAY IN CHANCE CATEGORY. TEMPS WILL BE ON THE WARM SIDE OF GUIDANCE WITH MOISTURE AND CLOUDS IN INCREASING SOUTHERLY FLOW. THE COLD FRONT WILL WAIT FOR THE MAIN UPPER TROUGH SWINGING AROUND A DEVELOPING CLOSED CENTER OVER THE GREAT LAKES FRIDAY...WHICH WILL THEN ACCELERATE THE FRONT EASTWARD DURING FRIDAY. AGAIN...AS WITH THE LAST SYSTEM...LOTS OF CLOUDS LIMITING HEATING AND TIMING OF THE FRONT WILL LESSEN DESTABILIZATION FOR FRIDAY CONVECTION. HOWEVER...GOOD DYNAMICS WILL STILL SUPPORT A BAND OF ORGANIZED CONVECTION ALONG AND AHEAD OF THE FRONT ON FRIDAY. FOR TIMING...WILL STILL GO WITH THE SLIGHTLY SLOWER NAM SOLUTION. WILL UP POPS TO LIKELY IN WEST AROUND 12Z...MOVE ACROSS THE REMAINDER OF THE AREA DURING THE DAY FRIDAY. BY FRIDAY EVENING...WHILE THE FRONT ITSELF MAY LAG A BIT BEHIND THE UPPER TROUGH...THE WESTERN EDGE OF THE DEEPER MOISTURE WILL MOVE INTO THE MOUNTAINS. THUS...WILL LOWER THE POPS SIGNIFICANTLY BEHIND THE WESTERN EDGE QPF THE DEEPER MOISTURE..BUT STILL KEEP SOME POPS WITH THE FRONT ITSELF. FRONT DOES EXITS THE MOUNTAINS BEFORE 12Z SATURDAY...WITH A DRY SLOT WORKING IN OVER MUCH OF THE AREA BY SATURDAY MORNING. MOST POPS BASICALLY END WITH THE PASSAGE OF THE FRONT LATER FRIDAY NIGHT. ALSO MUCH COOLER TEMPS WORK IN BY SATURDAY MORNING. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... SATURDAY WILL BE A TRANSITION CAY AS THE PROGRESSIVE UPPER LOW OVER THE GREAT LAKES LIFTS OUT. WRAPAROUND MOISTURE WILL BRING LOTS OD CLOUDS FOR MUCH OF SATURDAY...WITH LINGERING SHOWERS MAINLY IN THE NORTH. MUCH COOLER WITH TEMPS STRUGGLING TO REACH 80. HIGH PRESSURE TAKES CONTROL SUNDAY AND EARLY NEXT WEEK WITH DRY CONDITIONS AND SLOWING REBOUNDING TEMPS...THANKS TO SUNSHINE. ONE NOTE...THE GFS LOOKS TO BE THE OUTLIER ON A CLIPPER SYSTEM AND PRECIP ON TUESDAY. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... TRICKY FORECAST PINPOINTING WHICH AREAS WILL FOG TONIGHT. NORTHERN PORTIONS RECEIVED PCPN YESTERDAY AFTERNOON AND EVENING. HOWEVER...CLOUD COVER COULD BE THE PREVENTING FACTOR FOR DENSE VALLEY FOG. THEREFORE...DELAYED THE ONSET OF DENSE IFR FOG AT PKB...CKB AND EKN. STRONG CONVECTION FIRING UP ACROSS CENTRAL OH...MOVING NORTHEAST. RADAR IMAGES INDICATE AN OUTFLOW BOUNDARY FROM THIS COMPLEX EXTENDING SOUTH...AND TRACKING TOWARDS SOUTHEAST OH. WITH DEWPOINTS IN THE MID TO UPPER 60S...EXPECT THIS OUTFLOW BOUNDARY TO INTERACT WITH THE MOISTURE IN PLACE AND TRIGGER ADDITIONAL SHOWERS OR STORMS. ENOUGH CLEARING SHOULD SUFFICE FOR DENSE VALLEY FOG AT CRW AND CKB AROUND FROM 08-12Z TIME FRAME. DUE TO CLOUD COVER AROUND EKN...IFR IN 2SM EXPECTED AFTER 10Z. OTHER SITES MAY EXPERIENCE MVFR FOG CONDITIONS PER ABUNDANT MOISTURE THROUGH 13Z. BEST COVERAGE TO SCATTERED CONVECTION EXPECTED AFTER 18Z ACROSS OHIO INTO NORTHERN WEST VIRGINIA COMPARED TO COUNTIES FURTHER TO THE SOUTH. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: LINGERING CLOUDS FROM EVENING CONVECTION COULD DELAY OR DETER FOG FORMATION. 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. DATE THU 08/09/12 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EDT 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 CRW CONSISTENCY M L L L L L L M H H H H HTS CONSISTENCY M M M M M M M H H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY L L L L L L L L H H H H PKB CONSISTENCY M M L L L L L M H H H H CKB CONSISTENCY M M L L L L L M H H H H AFTER 06Z FRIDAY... IFR CONDITIONS POSSIBLE UNDER HEAVIEST SHOWERS/TSRA THURSDAY AFTERNOON AND EVENING. IFR CONDITIONS ALSO POSSIBLE FRIDAY WITH FRONT POST RAINFALL FOG. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JMV/26 NEAR TERM...KTB SHORT TERM...JMV LONG TERM...JMV AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1248 AM EDT THU AUG 9 2012 .SYNOPSIS... MID LEVEL WEAK SHORT WAVES MOVES FROM THE WEST OVERNIGHT. COLD FRONT AFFECTS THE AREA THURSDAY AND FRIDAY. HIGH PRESSURE BUILDS IN THIS WEEKEND WITH COOLER TEMPERATURES. && .NEAR TERM /UNTIL 8 AM THIS MORNING/... ADJUSTED SKY AND POP GRIDS PER LATEST RADAR AND SATELLITE IMAGES. ISOLATED CONVECTION CONTINUED TO FLARE ACROSS OUR SOUTHEASTERN COUNTIES TONIGHT. RADAR SHOWING STRONG PULSES WITH HIGH HAIL CORE ALOFT. COUPLE OF SEVERE STORM WARNINGS COULD BE ISSUED. ADDITIONAL CONVECTION IS NOTED OVER OH...MOVING NORTHEAST AROUND 20 KNOTS. THIS CONVECTION COULD REACH PORTIONS OF SOUTHEAST OH OVERNIGHT...CLOSER TO PERRY COUNTY OH. ADDITIONAL SHOWERS/STORMS COULD DEVELOP ALONG OUTFLOW BOUNDARIES SOUTH OF THIS CLUSTER TO AFFECT OTHER PORTIONS OF SOUTHEAST OH OVERNIGHT. MODELS SHOW SMALL VORT MAXES APPROACHING SOUTHEAST OH TONIGHT...OVER SFC DEWPOINTS IN THE MID TO UPPER 60S. PREVIOUS DISCUSSION BELOW... AT 02Z...HAVE SURFACE FRONT FROM NEAR PIT ON SW TO CMH...CVG...THEN WEST ACROSS SOUTHERN INDIANA. 00Z RAP SHOWS MAIN 500 VORT MAX CROSSING NRN WV MTNS BY 03Z...BUT HAS A WEAKENING VORT LINGERING IN NORTH CENTRAL WV THROUGH 06Z. MAY BE HELPING A FEW LINGERING STORMS CROSSING THE OHIO RIVER AT 02Z. WILL INCREASE AREAL COVERAGE OF THE FOG WHERE IT RAINS IN NRN CENTRAL WV...BUT NOT CONFIDENT ON THE EXACT INTENSITY. WILL LIMIT THE FOG IN SOUTHEAST OHIO SINCE BOUNDARY LAYER WINDS STAY UP...AND CLOUDS WITH THE NEXT 500 VORT MAX SHOULD BE APPROACHING BY THE PREDAWN HOURS. ALSO...INCREASED POPS A BIT FASTER FOR OUR SOUTHEAST OHIO COUNTIES DURING THE PREDAWN...WITH MORE SUPPORT ARRIVING...BEFORE LIFTING NE. && .SHORT TERM /8 AM THIS MORNING THROUGH FRIDAY NIGHT/... MODELS IN REASONABLE AGREEMENT WITH THE MASS FIELDS AS VIGOROUS UPPER LEVEL TROUGH AND ATTENDING COLD FRONT AFFECT OUR AREA FOR THE END OF THE WORKWEEK. IT IS SOMEWHAT OF A COMPLEX SYSTEM...AS THERE IS A LEAD UPPER TROUGH OUT AHEAD OF THE MAIN UPPER TROUGH. THIS LEAD UPPER TROUGH WILL OUTRUN THE FRONT AND MAY BRING SCATTERED SHOWERS AND THUNDERSTORMS THURSDAY NIGHT. WITHOUT A LOW LEVEL FOCUSING MECHANISM...WILL STAY IN CHANCE CATEGORY. TEMPS WILL BE ON THE WARM SIDE OF GUIDANCE WITH MOISTURE AND CLOUDS IN INCREASING SOUTHERLY FLOW. THE COLD FRONT WILL WAIT FOR THE MAIN UPPER TROUGH SWINGING AROUND A DEVELOPING CLOSED CENTER OVER THE GREAT LAKES FRIDAY...WHICH WILL THEN ACCELERATE THE FRONT EASTWARD DURING FRIDAY. AGAIN...AS WITH THE LAST SYSTEM...LOTS OF CLOUDS LIMITING HEATING AND TIMING OF THE FRONT WILL LESSEN DESTABILIZATION FOR FRIDAY CONVECTION. HOWEVER...GOOD DYNAMICS WILL STILL SUPPORT A BAND OF ORGANIZED CONVECTION ALONG AND AHEAD OF THE FRONT ON FRIDAY. FOR TIMING...WILL STILL GO WITH THE SLIGHTLY SLOWER NAM SOLUTION. WILL UP POPS TO LIKELY IN WEST AROUND 12Z...MOVE ACROSS THE REMAINDER OF THE AREA DURING THE DAY FRIDAY. BY FRIDAY EVENING...WHILE THE FRONT ITSELF MAY LAG A BIT BEHIND THE UPPER TROUGH...THE WESTERN EDGE OF THE DEEPER MOISTURE WILL MOVE INTO THE MOUNTAINS. THUS...WILL LOWER THE POPS SIGNIFICANTLY BEHIND THE WESTERN EDGE OPF THE DEEPER MOISTURE..BUT STILL KEEP SOME POPS WITH THE FRONT ITSELF. FRONT DOES EXITS THE MOUNTAINS BEFORE 12Z SATURDAY...WITH A DRY SLOT WORKING IN OVER MUCH OF THE AREA BY SATURDAY MORNING. MOST POPS BASICALLY END WITH THE PASSAGE OF THE FRONT LATER FRIDAY NIGHT. ALSO MUCH COOLER TEMPS WORK IN BY SATURDAY MORNING. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... SATURDAY WILL BE A TRANSITION CAY AS THE PROGRESSIVE UPPER LOW OVER THE GREAT LAKES LIFTS OUT. WRAPAROUND MOISTURE WILL BRING LOTS OD CLOUDS FOR MUCH OF SATURDAY...WITH LINGERING SHOWERS MAINLY IN THE NORTH. MUCH COOLER WITH TEMPS STRUGGLING TO REACH 80. HIGH PRESSURE TAKES CONTROL SUNDAY AND EARLY NEXT WEEK WITH DRY CONDITIONS AND SLOWING REBOUNDING TEMPS...THANKS TO SUNSHINE. ONE NOTE...THE GFS LOOKS TO BE THE OUTLIER ON A CLIPPER SYSTEM AND PRECIP ON TUESDAY. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... CONTINUES TO BE A CHALLENGING AVIATION FORECAST OVERNIGHT IN REGARDS TO DISSIPATING CONVECTION...LINGERING CLOUD DECK...AND FOG FORMATION. MID LEVEL 500 MB VORT MAX AXIS PASSES EAST...OVER NRN WV MOUNTAINS BY 03Z. CURRENTLY DO NOT HAVE HIGH ENOUGH POP FOR MENTION CONVECTION AT ELKINS...SINCE TIMING IS AROUND 02Z/03Z...AND WAS THINKING WEAKENING BY THEN. YET...CONVECTION SHOULD AFFECT PKB TO CKB TO WESTON CORRIDOR 00Z TO 02Z. WITH LOCAL VSBY NEAR 3 MILES AND CEILINGS 3 TO 4 THSD FT BKN. INITIALLY WAS THINKING LESS FOG OVERNIGHT PKB TO CKB...BUT WITH THE EVENING RAIN...WILL HOLD SOME THICKER FOG THERE 06Z TO 12Z. YET...WITH BOUNDARY LAYER AND 925 MB FLOW...HAVE THE VISIBILITY MORE VARIABLE ACROSS SOUTHEAST OHIO AND NORTHERN WEST VIRGINIA...COMPARED TO THE EKN-CRW AND SOUTHERN WV COAL FIELDS FOR 06Z TO 12Z. DID GO WITH LESS FOG TONIGHT AT HTS AND THE TRI STATE VICINITY THAN WE PREVIOUS HAD...COUNTING ON NO SHOWERS AND THAT LOW LEVEL FLOW. HAVE SOME 5 TO 8 THSD FT SCATTERED TO BROKEN CLOUDS FOR 12Z THURSDAY...AND MAYBE A RAIN SHOWER IN SOUTHEAST OHIO. THEN CLOUDS FORMING AT 3 TO 5 THSD FT SCATTERED TO BROKEN BY 15 TO 16Z. BEST COVERAGE TO SCATTERED CONVECTION EXPECTED AFTER 18Z ACROSS OHIO INTO NORTHERN WEST VIRGINIA COMPARED TO COUNTIES FURTHER TO THE SOUTH. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z FRIDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: LINGERING CLOUDS FROM EVENING CONVECTION COULD DELAY OR DETER FOG FORMATION. 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. DATE THU 08/09/12 UTC 1HRLY 02 03 04 05 06 07 08 09 10 11 12 13 EDT 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09 CRW CONSISTENCY H H M M H L L L L L L M HTS CONSISTENCY H H M M H H H M H H H H BKW CONSISTENCY H H H H H H H H H H H H EKN CONSISTENCY H H M L L L L L L L L L PKB CONSISTENCY H M M M H L L L L L L M CKB CONSISTENCY H H M M M L L L L L L M AFTER 06Z FRIDAY... IFR CONDITIONS POSSIBLE UNDER HEAVIEST SHOWERS/TSRA THURSDAY AFTERNOON AND EVENING. IFR CONDITIONS ALSO POSSIBLE FRIDAY WITH FRONT AS A RESULT OF CEILINGS AND SHOWERS/THUNDERSTORMS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...JMV/26 NEAR TERM...ARJ/KB SHORT TERM...JMV LONG TERM...JMV AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS TULSA OK
1144 PM CDT WED AUG 8 2012 ...UPDATE... .AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM. CONVECTION HAS WEAKENED CONSIDERABLY...WITH A FEW STORMS POSSIBLE AT KFYV/KXNA THROUGH AROUND 08Z. COLD FRONT WILL ENTER NORTHEAST OKLAHOMA THURSDAY MORNING AND PASS THROUGH ALL TAF SITES BY 20-22Z. DROPPED MENTION OF VCTS AT KMLC AND KFSM AS ANY ADDITIONAL DEVELOPMENT SHOULD STAY SOUTH OF THESE SITES THURSDAY AFTERNOON. && .PREV DISCUSSION... /ISSUED 944 PM CDT WED AUG 8 2012/ ..UPDATE... DISCUSSION... THE BULK OF EARLIER HEAVY CONVECTIVE ACTIVITY HAS MOVED SOUTH OUT OF THE AREA. A COUPLE OF ISOLATED SMALL THUNDERSTORMS REMAIN IN EASTERN OKLAHOMA... WITH SCATTERED STORMS CURRENTLY MOVING SOUTHWARD TOWARD FAR NORTHEAST OKLAHOMA AND NORTHWEST ARKANSAS. COOL AND MOIST OUTFLOW HAS MOVED ACROSS THE ENTIRE FORECAST AREA WITH THE EXCEPTION OF FAR WESTERN OSAGE AND PAWNEE COUNTIES. TEMPERATURES IN SOME RAIN-COOLED AREAS BRIEFLY DIPPED BELOW FORECAST OVERNIGHT LOWS BEFORE WARMING AGAIN. HAVE NOT CHANGED FORECAST LOWS SINCE DEWPOINTS HAVE NOW RISEN ENOUGH TO PUT A BOTTOM UNDER TEMPS. HOWEVER... HAVE UPDATED DEWPOINTS IN THE GRIDS AND ASSOCIATED CALCULATED GRID ELEMENTS. POPS FOR THE REMAINDER OF THE NIGHT LOOK GOOD... WITH HIGHEST CHANCES REMAINING TOWARD THE EAST. UPDATED PRODUCTS HAVE BEEN SENT. PREV DISCUSSION... /ISSUED 625 PM CDT WED AUG 8 2012/ .UPDATE... AVIATION... CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM. SCATTERED STRONG TO SEVERE STORMS ALONG WITH MULTIPLE OUTFLOW BOUNDARIES WILL CONTINUE TO RESULT IN ERRATIC WIND DIRECTIONS AND SPEEDS FOR THE NEXT SEVERAL HOURS. THUNDERSTORMS NEAR THE KMLC TAF SITE WILL GRADUALLY DIMINISH AFTER 02Z...WITH ADDITIONAL STORMS POTENTIALLY IMPACTING THE KFYV/KXNA SITES FROM THE NORTH BY 01-02Z. EXPECT PERIODIC MVFR/IFR CONDITIONS IN AND NEAR STORMS. MOST OF THE ACTIVITY SHOULD WEAKEN AFTER 06Z. A COLD FRONT WILL MOVE THROUGH THE REGION THURSDAY MORNING AND COULD RESULT IN A FEW LATE AFTERNOON STORMS FOR KMLC/KFSM. PREV DISCUSSION... /ISSUED 343 PM CDT WED AUG 8 2012/ DISCUSSION... ONGOING CONVECTION WILL MAINTAIN A RISK OF DAMAGING DOWNBURST WINDS ACROSS SE OK AND WESTERN AR INTO SUNSET...WITH ATTENTION THEN TURNING TO EXPANDING CONVECTION ACROSS THE CENTRAL PLAINS. THIS CONVECTION WILL BE FORCED BY A RESPECTABLE MID LEVEL WAVE FOR EARLY AUGUST...AND LIKELY DEVELOP SOUTH AND EASTWARD AFTER SUNSET. GIVEN THE DEEPLY MIXED AND NOT-YET OVERTURNED BOUNDARY LAYER IN PLACE ACROSS NE OK...THE CONVECTION WILL HAVE A GOOD CHANCE OF DEVELOPING INTO THE REGION. THE SOUTHWARD EXTENT SHOULD BE LIMITED BY THE ONGOING CONVECTION AND ITS EFFECTS ON STABILIZING THE BOUNDARY LAYER. THIS SCENARIO IS LARGELY SUPPORTED BY THE 18Z NAM AND HRRR OUTPUT. THE COLD FRONT ASSOCIATED WITH THE PASSING WAVE WILL MOVE INTO NE OK BY SUNRISE THURSDAY...AND THROUGH MUCH OF THE FORECAST AREA BY SUNSET THURSDAY. STORM CHANCES WILL RESIDE ALONG AND SOUTH OF THE BOUNDARY PRIMARILY DURING THE AFTERNOON HOURS ON THURSDAY. NOTICEABLY DRIER AND COOLER AIR WILL FOLLOW THE FRONT AND BRING TEMPS NEAR NORMAL FRIDAY AND SATURDAY. RAINFALL FOOTPRINTS...OR LACK THEREOF...MAY LARGELY AFFECT THE DEGREE OF COOLING GIVEN THE VERY WARM GROUND TEMPS AND LACK OF CLOUD COVER BEHIND THE FRONT. UPPER RIDGING WILL ATTEMPT TO EXPAND BACK EASTWARD OVER THE WEEKEND...THOUGH IT LOOKS TO BE SUPPRESSED FURTHER SOUTH AND NOT HAVE AS STRONG AS INFLUENCE AS RECENTLY. SOUTHERN PERIPHERY OF A PASSING WAVE MAY SUPPORT PRECIP LATE SUNDAY INTO MONDAY...OTHERWISE NO SIGNIFICANT PRECIP CHANCES ARE NOTED UNTIL POSSIBLY JUST BEYOND THIS FORECAST TIME FRAME. && .PRELIMINARY POINT TEMPS/POPS... TUL 75 100 69 92 / 30 10 0 0 FSM 74 104 70 93 / 30 10 10 10 MLC 71 103 69 94 / 30 0 10 0 BVO 69 99 64 92 / 30 10 0 0 FYV 67 97 64 87 / 40 10 10 0 BYV 70 95 66 85 / 50 10 10 0 MKO 73 102 69 93 / 40 10 10 0 MIO 71 97 68 88 / 40 10 0 0 F10 73 102 70 93 / 30 0 0 0 HHW 70 103 73 95 / 30 20 10 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...NONE. AR...NONE. && $$ AVIATION...18
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
808 PM EDT FRI AUG 10 2012 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE WEST THIS AFTERNOON AND SHOULD GET HUNG UP ACROSS THE MOUNTAINS TONIGHT. THE FRONT IS EXPECTED TO PUSH THROUGH LATE SATURDAY AND THEN SOUTH OF THE AREA ON SUNDAY. HIGH PRESSURE WILL MOVE IN FOR THE EARLY PART OF NEXT WEEK. MEANWHILE ANOTHER FRONT WILL APPROACH THE AREA BY MID WEEK. && .NEAR TERM /THROUGH SATURDAY/... AS OF 530 PM...A STRONG STORM HAS MOVED INTO RABUN COUNTY...AND A LINE OF CONVECTION IS ORGANIZING OVER THE GREAT VALLEY OF TN. HOWEVER...NOT MUCH IS HAPPENING OVER THE ERN FOOTHILLS AND PIEDMONT ZONES ATTM AND I/VE CUT BACK POPS IN THOSE LOCATIONS FOR THE NEXT COUPLE HOURS. THERE CONTINUES TO BE GOOD MODEL AGREEMENT THAT CONVECTION WILL BECOME MORE WIDESPREAD THROUGH BOTH AN MCS MOVING INTO THE NC MTNS AND CONVECTION DEVELOPING IN STRENGTHENING LLVL CONVERGENCE ACROSS THE FOOTHILLS LATER THIS EVENING. AND THIS IS REFLECTED WELL IN THE GRIDS. AS OF MID AFTERNOON...VISIBLE SATELLITE IMAGERY SHOWS LOW CONVECTIVE CLOUDS SCATTERING SUFFICIENTLY E OF THE BLUE RIDGE TO ALLOW HEATING THAT HAS RAISED SFC-BASED CAPE INTO THE 1500-2000 J/KG RANGE ON THE LAPS ANALYSIS. SHOWER ACTIVITY HAS DEVELOPED OVER THE CLT METRO AREA AND ALONG THE BLUE RIDGE...WITH MORE ACTIVITY CLOSER TO THE FRONT OVER THE CUMBERLAND PLATEAU. EXPECT SHOWERS AND STORMS TO CONTINUE DEVELOPING AND BECOMING MORE NUMEROUS...MAINLY OVER THE MTNS AND FOOTHILLS...THROUGH THE LATE AFTERNOON. SEVERE WEATHER REMAINS A CONCERN WITH SOME DRY AIR ABOVE 500 MB...ALTHO IN GENERAL THE SOUNDINGS DO NOT LOOK AS FAVORABLE AS YESTERDAY. OVER THE NEXT 24 HOURS OR SO...THE MODELS ARE IN GOOD AGREEMENT WITH THE EVOLUTION OF WEATHER FEATURES...AND IN PARTICULAR SHOW THE AXIS OF THE UPPER TROF AND THE UPPER JET REMAINING TO OUR WEST. THIS WILL ACT TO KEEP THE SURFACE FRONT HUNG UP PROBABLY OVER THE MTNS THROUGH SATURDAY AFTERNOON. THE TREND...THEREFORE...IS TO HOLD ON TO MORE OF A CHANCE OF SHOWER/TSTM ACTIVITY OVER A LARGER PART OF THE FCST AREA THROUGH 00Z SUNDAY. THE THREAT OF SEVERE STORMS WILL SLOWLY INCREASE AS BUOYANCY AND DCAPE SLOWLY BECOME MORE FAVORABLE...WITH JUST ENOUGH SHEAR TO PERHAPS ORGANIZE STORMS EARLY THIS EVENING. THE 4KM WRF DEVELOPS A LINE OF STORMS OFF THE BLUE RIDGE AROUND 23Z WHILE THE HRRR BRINGS THE LINE OF STORMS ACROSS TN AND INTO THE NC MTNS AROUND THAT TIME. ABUNDANT LOW LEVEL MOISTURE AND ENUF UPPER FORCING WILL EXIST TO WARRANT A LIKELY POP INTO THE EVENING HOURS. WILL KEEP POP IN THE CHANCE RANGE OVERNIGHT AS ADDITIONAL STORMS COULD REDEVELOP AT ANY TIME WITH THE SITUATION REMAINING UNCHANGED. TEMPS WILL REMAIN MILD. ON SATURDAY...EXPECT THE FRONT TO BE HUNG UP OVER THE MTNS AT SUNRISE. UNLESS EXTENSIVE CONVECTIVE DEBRIS PREVENTS IT...CONVECTION SHOULD RE-FIRE EARLY IN THE DAY CLOSE TO THE FRONT AS IT DID TO OUR WEST THIS PAST MORNING. UPPER DIVERGENCE...DPVA...AND PLENTY OF MOISTURE SUGGEST ANOTHER POP IN THE LIKELY RANGE BY AFTERNOON OVER THE PIEDMONT...AND A CHANCE UP TO THE BLUE RIDGE. A GUIDANCE BLEND WAS USED FOR HIGH TEMPS. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/... AT 200 PM EDT FRIDAY...12Z GFS AND NAM STILL SOMEWHAT AT ODDS AS TO HOW FAST THE FRONTAL BAND OF DEEP LAYER MOISTURE AND PRECIP WILL EXIT THE FORECAST AREA OVER THE EAST. THE NAM STIL IS FASTER AND HAS THE DEEP LAYER FRONTAL MOISTURE EAST OF THE AREA BY 00Z SUN...WHILE THE GFS IS CONSIDERABLY SLOWER AND WETTER. THE SREF APPEARS TO CONTINUE TO BE A GOOD COMPROMISE FOR THE SOLUTION. THE SREF KEEPS PRECIP CHANCES OVER THE EASTERN MOST PART OF THE FORECAST AREA EARLY ON SAT NIGHT...AND THEN MOVES THE MOISTURE/PRECIP EAST BY MIDNIGHT. WILL ALSO SCATTER AND CLEAR THE CLOUDS FROM NW TO SE SAT NIGHT. HIGH PRESSURE BUILDS OVER THE AREA ON SUN WHICH SHOULD PRODUCE A VERY NICE DAY WITH DEWPOINTS MIXING OUT INTO THE 50S OVER THE MOUNTAINS AND LOW 60S ELSEWHERE. THE HIGH SHIFTS EAST OF THE AREA ON MONDAY...BUT ITS LINGERING INFLUENCE SHOULD ALLOW FOR ANOTHER DRY DAY ON MONDAY. TEMPS ARE EXPECTED TO BE SLIGHTLY BELOW CLIMO ON SUN AND NEAR CLIMO ON MON. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AT 130 PM EDT FRIDAY...A SOMEWHAT PROGRESSIVE PATTERN APPEARS TO BE IN STORE DURING THE MEDIUM RANGE. THE UPPER AIR PATTERN WILL GENERALLY FEATURE A MEAN TROUGH OVER THE EASTERN U.S. WITH INDICATIONS FROM THE LATEST 12Z GFS OF BUILDING HEIGHTS TOWARD THE END OF NEXT WEEK OVER THE EAST. LATEST HPC/GFS GUIDANCE SUGGESTS A WEAK COLD FRONT WILL CROSS THE REGION ON TUE ALONG WITH SCATTERED CONVECTION. THE GFS DRIVES THE FRONT SE OF THE AREA BY WED WITH HIGH PRESSURE BUILDING IN THROUGH THU. THUS ONLY CLIMO TYPE POPS FOR AFTERNOON CONVECTION IN THE MOUNTAINS WED AND THU. ANOTHER FRONT APPROACHES THE AREA ON FRI AND PER HPC WILL FORECAST CHANCE TYPE POPS. TEMPS SHOULD BE NEAR CLIMO THROUGH THE PERIOD. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... AT KCLT...AN AREA OF SHRA WAS ABOUT 40 MI WEST OF THE AIRFIELD AT ISSUANCE TIME. IF THEY DEVELOP FURTHER THEY COULD GET CLOSE ENUF TO WARRANT A VCTS IN ABOUT AN HOUR. STILL EXPECTING SHRA/TSTMS TO DEVELOP AS THE EVENING PROGRESSES...THOUGH I/VE PUSHED THE TEMPO GROUP FOR THUNDER BACK AN HOUR...TO 02-05 UTC. IFR STRATUS IS EXPECTED TO DEVELOP AGAIN TONIGHT. HOWEVER...IF THERE ISN/T MUCH PCPN AROUND THE AIRFIELD...THEN THE LOW CLOUDS MAY STAY TO THE SOUTHEAST...DOWN ACROSS THE MIDLANDS. WINDS WILL GENERALLY BE FROM THE S TO SW OVERNIGHT AND SATURDAY. A COLD FRONT WILL STALL OVER THE FOOTHILLS TMRW WITH MORE THUNDERSTORMS DEVELOPING OVER THE PIEDMONT IN THE AFTN AND EVENING HOURS. ELSEWHERE...AS A COLD FRONT ENTERS THE MOUNTAINS THIS EVENING...SHRA/TSTMS WILL INCREASE IN COVERAGE ACROSS THE REGION. I STILL EXPECT ENOUGH COVERAGE THAT TEMPO GROUPS HAVE BEEN INCLUDED AT ALL TAF SITES FOR VARIOUS PERIODS OF TIME INTO THE EARLY MORNING HOURS. THERE WAS AN AREA OF TSTMS NOT TOO FAR NW OF KGSP AND KGMU AT ISSUANCE TIME ALONG WITH OTHER STRONG STORMS ABOUT 15 MILES NORTH OF KAVL. LATER TONIGHT VALLEY FOG IS A GOOD BET ACROSS THE FRENCH BROAD VALLEY...ESPECIALLY IF THERE IS LATE NIGHT CLEARING. THE LOW LEVEL WINDS WILL VEER AROUND TO THE SW OVER THE FOOTHILLS AND PIEDMONT. THIS MAY CAUSE IFR CIGS TO DEVELOP SOUTH OF ALL THE TAF SITES...DOWN ACROSS THE MIDLANDS. HOWEVER...IF THERE IS FAIRLY WIDESPREAD RAIN WITH SHRA/TSTMS...THEN THE LOW CLOUDS SHOULD FORM CLOSER TO THE MTNS. I/M BANKING ON THIS AND HAVE INCLUDED IFR CIGS LATER TONIGHT...IN LINE WITH THE MODEL GUIDANCE. OUTLOOK...A COLD FRONT WILL SLOWLY CROSS THE AREA LATE SATURDAY... WITH DRIER HIGH PRES BUILDING IN FROM THE W THE LATTER HALF OF THE WEEKEND. WEAK HIGH PRESSURE WILL LINGER THROUGH EARLY NEXT WEEK. AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)... WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PM NEAR TERM...MCAVOY SHORT TERM...LG LONG TERM...LG AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1110 PM CDT WED AUG 8 2012 .DISCUSSION... SEE AVIATION DISCUSSION BELOW... && .AVIATION... MOST OF THE CONVECTION ACROSS THE AREA HAS DISSIPATED THIS EVENING...WITH A FEW LIGHT SHOWERS ACROSS THE NORTHWEST HILL COUNTRY. EXPECT WINDS TO REMAIN LIGHT AND VARIABLE WITH VFR CONDITIONS PREVAILING THROUGH THE PERIOD. AN ISOLATED SHOWER OR THUNDERSTORMS IS POSSIBLE THURSDAY AFTERNOON AT KJCT AND KSOA...BUT CONFIDENCE IS TOO LOW TO INCLUDE IN THE CURRENT TAF PACKAGE. && .PREV DISCUSSION... /ISSUED 601 PM CDT WED AUG 8 2012/ DISCUSSION... SEE AVIATION DISCUSSION BELOW... AVIATION... A BROKEN LINE OF SHOWERS AND THUNDERSTORMS WAS LOCATED ALONG A LINE FROM NEAR OZONA...TO FORT MCKAVETT...TO BRADY. EXPECT THIS ACTIVITY TO CONTINUE TO MOVE SOUTH THROUGH THE NEXT COUPLE OF HOURS. AN ISOLATED SHOWER OR THUNDERSTORM WILL BE POSSIBLE AT MAINLY KBBD...KJCT AND KSOA...WITH MOST OF THE ACTIVITY WINDING DOWN BY 02Z. BRIEF HEAVY RAINFALL AND GUSTY WINDS TO NEAR 40 MPH WILL BE POSSIBLE WITH THESE STORMS. TONIGHT THROUGH LATE THURSDAY MORNING...EXPECT VFR CONDITIONS AND LIGHT AND VARIABLE WINDS. PREV DISCUSSION... /ISSUED 359 PM CDT WED AUG 8 2012/ SHORT TERM... SHOWERS AND THUNDERSTORMS ARE DEVELOPING ACROSS THE HEARTLAND AND CONCHO VALLEY THIS AFTERNOON. THIS ACTIVITY IS DEVELOPING IN ASSOCIATION WITH LIFT FROM A WEAK SHORT WAVE THAT IS OVERSPREADING THE AREA FROM THE NORTH. LATEST HRRR SEEMS TO BE DOING A DECENT JOB SO FAR AND INDICATES ADDITIONAL DEVELOPMENT ACROSS THE SOUTHERN HALF OF THE FORECAST AREA THROUGH EARLY EVENING. WILL MAINTAIN 30 POPS SOUTH AND SLIGHT CHANCE POPS NORTH ACROSS THE BIG COUNTRY THROUGH THE EVENING HOURS. MAY STILL SEE SOME LINGERING ACTIVITY ALONG THE I-10 CORRIDOR THROUGH LATE EVENING BUT MOST OF THE CONVECTION SHOULD DISSIPATE AFTER SUNEST. THE MAIN THREAT FROM THUNDERSTORMS WILL BE LOCALLY HEAVY RAINFALL...GUSTY WINDS AND DANGEROUS CLOUD TO GROUND LIGHTNING. DRIER AIR WILL FILTER INTO THE AREA FROM THE NORTH LATER TONIGHT AND THURSDAY. THIS WILL RESULT IN DRY AND HOT CONDITIONS ACROSS THE AREA WITH AFTERNOON HIGHS AROUND THE CENTURY MARK. CANNOT RULE OUT AN ISOLATED STORM OR TWO ACROSS SOUTHEAST SECTIONS THURSDAY AFTERNOON SO KEPT ISOLATED MENTION OVER THIS AREA. LONG TERM... AS AN UPPER TROUGH AND LOW DROP SOUTHEAST ACROSS THE LOWER GREAT LAKES REGION...TRAILING PORTION OF ASSOCIATED COLD FRONT WILL MOVE SOUTH INTO THE BIG COUNTRY THURSDAY NIGHT... AND ACROSS THE REST OF WEST CENTRAL TEXAS ON FRIDAY. THIS PORTION OF THE FRONT WILL BE WEAK HOWEVER...WITH THE MAIN ADVECTION OF COOLER AIR EXPECTED TO BE TO THE NORTHEAST OF OUR AREA. WITH WEAK SURFACE CONVERGENCE AND A DRIER AIRMASS PROGGED...RAIN CHANCES LOOK LOOK TOO SMALL INCLUDE IN OUR AREA WITH THE ARRIVAL/PASSAGE OF THIS FRONT. TEMPERATURES WILL BE SLIGHTLY COOLER ACROSS THE BIG COUNTRY...WHERE HIGHS FRIDAY ARE EXPECTED TO BE IN THE MID/UPPER 90S. THE UPPER HIGH WILL BE CENTERED OVER NEW MEXICO DURING THE WEEKEND. GIVEN ITS PROXIMITY...HOT AND DRY CONDITIONS CAN BE EXPECTED FOR WEST CENTRAL TEXAS. THE WARMEST READINGS ARE EXPECTED SUNDAY...WHEN HIGHS SHOULD RANGE FROM 100-105 DEGREES AREAWIDE. LITTLE CHANGE IS INDICATED WITH THIS PATTERN THROUGH AT LEAST EARLY NEXT WEEK. THE 12Z GFS AND ECMWF SHOW A WEAKENING WITH THIS HIGH BY NEXT TUESDAY OR WEDNESDAY...WITH THE GFS BRINGING A DISTURBANCE NORTH-NORTHEAST FROM THE LOWER RIO GRANDE VALLEY INTO CENTRAL AND EASTERN TEXAS. GIVEN THAT THIS IS LATE DAY 6 AND DAY 7...LEANING AT THIS TIME TOWARD PERSISTENCE WITH THE FORECAST. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 74 101 72 97 70 / 20 10 10 5 5 SAN ANGELO 74 101 73 101 70 / 20 20 10 10 5 JUNCTION 73 97 72 101 70 / 20 20 10 10 5 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DANIELS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
929 PM CDT FRI AUG 10 2012 .SHORT TERM...TONIGHT 929 PM CDT FRI AUG 10 2012 STILL HAVE NOT SEEN MUCH RECOVERY IN THE DEW POINTS THIS EVENING. IN MOST LOCATIONS...THE DEW POINTS HAVE ONLY CLIMBED 2 DEGREES. WITH THE EXCEPTION OF KVOK...KTOB..KOVS...AND KFKA...THE TEMPERATURE/DEW POINT SPREADS ARE GREATER THAN 10 DEGREES. WITH SURFACE RIDGE BUILDING SOUTHEAST ACROSS THE AREA...THE SURFACE WINDS HAVE DECREASED AS EXPECTED. HOWEVER THERE IS STILL A 10 TO 15 KNOT WIND AT THE OFFICE AND THE RAP CONTINUES TO SHOW THESE WINDS WILL REMAIN LIKE THIS ALL NIGHT. AS A RESULT... THINKING THAT THE FOG POSSIBILITY AT KLSE IS NOT THAT GREAT. THIS WILL LIKELY THE CASE IN THE ENTIRE UPPER MISSISSIPPI RIVER VALLEY. ONE CASE THAT LOOKS LIKELY TO SEE VALLEY FOG WILL BE IN THE WISCONSIN AND THE LOWER PORTION OF KICKAPOO RIVER VALLEY. ALSO WOULD NOT BE SURPRISED TO SEE SOME FOG NEAR VOLK FIELD. .LONG TERM...TUESDAY THROUGH FRIDAY 253 PM CDT FRI AUG 10 2012 10.12 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT TUESDAY THROUGH EARLY THURSDAY THEN DIVERGE GREATLY LATE THURSDAY THROUGH FRIDAY. A BRIEF WARM UP IS IN STORE FOR THE AREA TUESDAY INTO WEDNESDAY WITH HIGHS REBOUNDING INTO THE LOWER 80S. A STRONG COLD FRONT IS EXPECTED TO PUSH INTO THE AREA DURING THE DAY ON THURSDAY BRINGING SHOWERS AND THUNDERSTORMS TO THE AREA. STRONG SHEAR APPEARS TO BE LACKING WITH THE LATEST SET OF FORECAST MODEL RUNS DURING THE DAY ON THURSDAY WITH THE STRONGEST SHEAR WELL BEHIND THE COLD FRONT. DETAILS THIS FAR OUT ARE UNCLEAR WITH THE VARYING MODEL SOLUTIONS SO DIFFICULT TO DETERMINE SEVERE WEATHER POTENTIAL WITH THIS SYSTEM. MODELS ARE POINTING TOWARDS A COOL DOWN FOR LATE NEXT WEEK BEHIND THE FRONT AS A LONG WAVE TROUGH DEVELOPS ACROSS THE UPPER MIDWEST/GREAT LAKES. AT THIS TIME IT APPEARS THAT HIGHS WILL STRUGGLE TO GET OUT OF THE 60S ON FRIDAY. && .AVIATION...TONIGHT AND SATURDAY 645 PM CDT FRI AUG 10 2012 HIGH PRESSURE...CURRENTLY LOCATED OVER NORTHERN MINNESOTA...WILL BUILD SOUTHEAST INTO THE REGION TONIGHT. WHILE THE BOUNDARY LAYER WILL LIKELY DECOUPLE AND GO CALM AFTER MIDNIGHT...THE LATEST RAP CONTINUES TO SUGGEST THAT THE WINDS JUST ABOVE THE BOUNDARY LAYER WILL BE NORTHEAST AT 10 TO 15 KNOTS. IN ADDITION...THERE ARE STILL SOME QUESTIONS ON HOW DRY THE DEW POINTS WILL BECOME THIS EVENING IN THE RIVER VALLEYS AND HOW MUCH RECOVERING WILL BE SEEN OVERNIGHT. AS A RESULT...IT IS NOT SURPRISING THAT THE RAP AND NAM/WRF SOUNDINGS CONTINUE TO SHOW VERY SHALLOW MOISTURE AT KLSE. AS A RESULT...JUST KEPT THE VCFG GOING AT KLSE. MEANWHILE FURTHER SOUTH...EXPECT TO SEE SOME VALLEY FOG DEVELOP IN THE WISCONSIN AND KICKAPOO RIVER VALLEY AFTER 11.06Z AND DISSIPATE AROUND 11.13Z. && .ARX WATCHES/WARNINGS/ADVISORIES... 253 PM CDT FRI AUG 10 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM...WETENKAMP AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
646 PM CDT FRI AUG 10 2012 .SHORT TERM...TONIGHT THROUGH MONDAY 253 PM CDT FRI AUG 10 2012 MAIN FORECAST CONCERNS ARE ON AREAS OF VALLEY FOG TONIGHT AND OVERNIGHT LOWS. FOCUS THEN TURNS TO RAIN CHANCES EARLY SUNDAY MORNING THROUGH MONDAY. CURRENT WATER VAPOR IMAGERY SHOWED AN UPPER LOW OVER SOUTHERN LOWER MICHIGAN. SURFACE OBSERVATIONS SHOWED SURFACE HIGH PRESSURE EXTENDING FROM CENTRAL ONTARIO...SOUTHWEST INTO THE EASTERN DAKOTAS. THE SURFACE LOW WAS LOCATED OVER EXTREME SOUTHEAST LOWER MICHIGAN. THE POSITION OF THESE TWO FEATURES PLACES THE FORECAST AREA IN COOL NORTHEAST FLOW. THE LOW WILL LIFT NORTHEAST TONIGHT OVER LAKE HURON AS HIGH PRESSURE EDGES INTO THE FORECAST AREA FROM THE WEST. PLAN ON MOSTLY CLEAR SKIES TONIGHT WITH AREAS OF FOG DEVELOPING. THERE IS SOME UNCERTAINTY REGARDING THE EXTENT OF THE FOG COVERAGE. THE AREA STAYS IN A MODEST PRESSURE GRADIENT PRODUCING LIGHT NORTHEAST WINDS. IN ADDITION IT APPEARS WINDS JUST ABOVE THE SURFACE THROUGH 1 KFT WILL REMAIN IN THE 11 TO 15 KTS THROUGH MUCH OF THE NIGHT. THE WINDS ALOFT ALONG WITH A VERY DRY AIRMASS IN PLACE WOULD NOT BE FAVORABLE FOR A WIDESPREAD VALLEY FOG EVENT. HAVE SEEN GUIDANCE IN THE PAST OVERDO THE WINDS ALOFT IN THESE SCENARIOS BUT THE LOW IS TAKING ITS TIME MOVING TO THE EAST...KEEPING US IN THE GRADIENT. WILL HAVE TO MONITOR WINDS VERY CLOSELY AT BLUFFTOP TONIGHT TO WATCH FOR A DECREASE. IF WINDS DROP OFF...WOULD EXPECT TO SEE WIDESPREAD VALLEY FOG. WITH THE UNFAVORABLE CONDITIONS POSSIBLE TONIGHT...WILL DROP FOG COVERAGE BACK TO AREAS AND MONITOR CLOSELY THROUGH THE EVENING HOURS. PLAN ON CHILLY OVERNIGHT LOWS WITH TEMPERATURES FALLING INTO THE LOWER 50S TO MID 40S. THE COOLEST AREAS WILL BE IN LOW LYING AREAS SUCH AS DIAMOND LAKE AND BLACK RIVER FALLS. HIGH PRESSURE WILL BE CENTERED OVER THE FORECAST AREA ON SATURDAY PROVIDING SUNNY SKIES AND PLEASANT TEMPERATURES. OTHER THAN SOME EARLY MORNING FOG...PLAN ON A VERY NICE DAY WITH HIGHS RANGING FROM THE LOWER 70S ACROSS NORTH CENTRAL WISCONSIN TO THE UPPER 70S OVER NORTHEAST IOWA. WILL HAVE TO KEEP A CLOSE WATCH ON DEWPOINTS DURING THE AFTERNOON HOURS WITH DEEP MIXING EXPECTED. THE HIGH IS EXPECTED TO MOVE EAST OF THE AREA LATE SATURDAY NIGHT AS A POTENT SHORTWAVE TROUGH MOVES ACROSS THE DAKOTAS. THE TROUGH IS EXPECTED TO DIVE INTO IOWA/NORTHERN MISSOURI DURING THE DAY ON SATURDAY. THIS FEATURE WILL BRING A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS TO LOCATIONS WEST OF THE MISSISSIPPI RIVER DURING THE OVERNIGHT HOURS. HIGHER CHANCES FOR SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED ACROSS THE FORECAST AREA DURING THE DAY ON SUNDAY. THE BULK OF THE FORCING WITH THE WAVE WILL BE ACROSS IOWA...SO NOT EXPECTING TO SEE ANYTHING MORE THAN SCATTERED SHOWERS NORTH OF INTERSTATE 90. HOWEVER...STRONG MOISTURE TRANSPORT FOCUSED INTO THIS SYSTEM COUPLED WITH DEEPENING LOW PRESSURE WILL RESULT IN SWATH OF APPRECIABLE RAINFALL AMOUNTS. GUIDANCE IS SUGGESTING RAINFALL AMOUNTS OF 1 TO 2 INCHES POSSIBLE...WITH LOCALLY HIGHER AMOUNTS NOT OUT OF THE QUESTION. THE 12Z NAM SHOWS THIS SWATH OF HEAVY RAIN ACROSS CENTRAL IOWA INTO NORTHERN ILLINOIS AND JUST GRAZING PORTIONS OF NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. THE GFS IS SLIGHTLY FURTHER NORTH....AND THE GEM IS AS FAR NORTH AS THE I-90 CORRIDOR. GIVEN THE SPREAD IN MODEL SOLUTIONS...CHOSE TO GO WITH A MODEL CONSENSUS BLEND WITH THE HIGHEST CHANCES FOR SHOWERS AND ISOLATED THUNDERSTORMS ACROSS PORTIONS OF NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. THIS SYSTEM WILL NEED TO BE MONITORED VERY CLOSELY THE NEXT SET OF MODEL RUNS. IF IT SHIFTS FURTHER NORTH...HEAVY RAINFALL WILL BE POSSIBLE FOR LOCATIONS SOUTH OF INTERSTATE 90. WITH ABUNDANT CLOUD COVER ACROSS THE AREA ON SUNDAY AND THE RAIN...PLAN ON HIGHS ON SUNDAY RANGING FROM THE THE MID 70S ACROSS NORTHERN WISCONSIN TO THE UPPER 60S TO AROUND 70 OVER NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. A FEW SHOWERS WILL LINGER ACROSS THE FORECAST AREA MONDAY MORNING...AND PERHAPS INTO EARLY MONDAY AFTERNOON BEFORE THE TROUGH FINALLY EXITS THE AREA. OTHERWISE PLAN ON DECREASING CLOUDS ACROSS THE FORECAST AREA ON MONDAY WITH HIGHS IN THE 70S TO AROUND 80. A BRIEF BREAK IN PRECIPITATION CHANCES IS EXPECTED MONDAY NIGHT INTO TUESDAY AS UPPER LEVEL RIDGING MOVES OVER THE AREA AHEAD OF A BROAD UPPER LEVEL TROUGH APPROACHING THE REGION FROM MANITOBA/SASKATCHEWAN. LOOK FOR OVERNIGHT LOWS ON MONDAY TO FALL INTO THE 50S. .LONG TERM...TUESDAY THROUGH FRIDAY 253 PM CDT FRI AUG 10 2012 10.12 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT TUESDAY THROUGH EARLY THURSDAY THEN DIVERGE GREATLY LATE THURSDAY THROUGH FRIDAY. A BRIEF WARM UP IS IN STORE FOR THE AREA TUESDAY INTO WEDNESDAY WITH HIGHS REBOUNDING INTO THE LOWER 80S. A STRONG COLD FRONT IS EXPECTED TO PUSH INTO THE AREA DURING THE DAY ON THURSDAY BRINGING SHOWERS AND THUNDERSTORMS TO THE AREA. STRONG SHEAR APPEARS TO BE LACKING WITH THE LATEST SET OF FORECAST MODEL RUNS DURING THE DAY ON THURSDAY WITH THE STRONGEST SHEAR WELL BEHIND THE COLD FRONT. DETAILS THIS FAR OUT ARE UNCLEAR WITH THE VARYING MODEL SOLUTIONS SO DIFFICULT TO DETERMINE SEVERE WEATHER POTENTIAL WITH THIS SYSTEM. MODELS ARE POINTING TOWARDS A COOL DOWN FOR LATE NEXT WEEK BEHIND THE FRONT AS A LONG WAVE TROUGH DEVELOPS ACROSS THE UPPER MIDWEST/GREAT LAKES. AT THIS TIME IT APPEARS THAT HIGHS WILL STRUGGLE TO GET OUT OF THE 60S ON FRIDAY. && .AVIATION...TONIGHT AND SATURDAY 645 PM CDT FRI AUG 10 2012 HIGH PRESSURE...CURRENTLY LOCATED OVER NORTHERN MINNESOTA...WILL BUILD SOUTHEAST INTO THE REGION TONIGHT. WHILE THE BOUNDARY LAYER WILL LIKELY DECOUPLE AND GO CALM AFTER MIDNIGHT...THE LATEST RAP CONTINUES TO SUGGEST THAT THE WINDS JUST ABOVE THE BOUNDARY LAYER WILL BE NORTHEAST AT 10 TO 15 KNOTS. IN ADDITION...THERE ARE STILL SOME QUESTIONS ON HOW DRY THE DEW POINTS WILL BECOME THIS EVENING IN THE RIVER VALLEYS AND HOW MUCH RECOVERING WILL BE SEEN OVERNIGHT. AS A RESULT...IT IS NOT SURPRISING THAT THE RAP AND NAM/WRF SOUNDINGS CONTINUE TO SHOW VERY SHALLOW MOISTURE AT KLSE. AS A RESULT...JUST KEPT THE VCFG GOING AT KLSE. MEANWHILE FURTHER SOUTH...EXPECT TO SEE SOME VALLEY FOG DEVELOP IN THE WISCONSIN AND KICKAPOO RIVER VALLEY AFTER 11.06Z AND DISSIPATE AROUND 11.13Z. && .ARX WATCHES/WARNINGS/ADVISORIES... 253 PM CDT FRI AUG 10 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
109 PM CDT THU AUG 9 2012 .SHORT TERM...TODAY THROUGH SATURDAY 241 AM CDT THU AUG 9 2012 MAIN CONCERNS INCLUDE RAIN CHANCES TODAY INTO THIS EVENING/FOG FRIDAY NIGHT/TEMPERATURES THROUGH THE PERIOD. LATEST WATER VAPOR IMAGERY/RAP 500MB ANALYSIS SHOWING A MID-LEVEL SHORTWAVE TROUGH MOVING SOUTHEAST ACROSS SOUTHERN WI/EASTERN IA. ANOTHER MORE VIGOROUS SHORTWAVE WAS MOVING SOUTH THROUGH WESTERN ONTARIO/ARROWHEAD REGION OF MN. SOUTHERN SHORTWAVE TROUGH DEFORMATION AREA WAS PRODUCING SOME 700MB FRONTOGENETIC FORCING AND RESULTING IN SCATTERED -SHRA ACTIVITY MAINLY EAST OF THE MISSISSIPPI RIVER. RAP SHOWS THIS FRONTOGENESIS WEAKENING OVER THE NEXT FEW HOURS...AND RADAR MOSAIC ALREADY SHOWING DISSIPATION OF THE SHRA ACTIVITY. MEANWHILE...THE TROUGH DROPPING SOUTH THROUGH ONTARIO/NORTHERN MN WAS PRODUCING A MORE ORGANIZED BAND OF SHRA/ISOLD THUNDER IN GOOD 700-300MB PV-ADVECTION PER THE RAP. OTHERWISE...SKIES ACROSS THE AREA WERE MOSTLY CLOUDY WITH TEMPERATURES IN THE 60S. LATEST NCEP MODELS/SREF REMAIN IN GOOD AGREEMENT THROUGH THE SHORT TERM PERIOD. FOR TODAY...WILL BE WATCHING THE WAVE OVER ONTARIO/NORTHERN MN DROP SOUTHEAST ACROSS THE AREA. INCREASING PV-ADVECTION/STEEPENING LAPSE RATES ACROSS THE AREA WILL LEAD TO MORE SHOWER/THUNDER DEVELOPMENT. BEST FORCING APPEARS TO BE EAST OF THE MISSISSIPPI...SO TRENDED POPS HIGHER THERE. IN ADDITION...THE NAM INDICATING 0-3KM MUCAPE INCREASING INTO THE 1000-1500J/KG RANGE BY NOON WITH BULK SHEAR IN THE 15 TO 30KT RANGE FOR PERHAPS SOME LINEAR ORGANIZATION OF THE CONVECTION. WITH THIS IN MIND...ALONG WITH COLDER AIR ALOFT AND LOWERING WET BULB ZERO HEIGHTS...WILL HAVE TO WATCH FOR ISOLATED SEVERE THREAT TODAY WITH HAIL AND WIND BEING THE MAIN THREATS. OTHERWISE...TEMPERATURES WILL BE A BIT COOLER WITH THE TROUGH/SCATTERED CONVECTION. ANTICIPATING HIGHS TODAY RANGING FROM THE UPPER 60S ACROSS NORTH CENTRAL WI...TO THE LOWER/MID 70S ELSEWHERE. LOOK FOR THE TROUGH TO DEEPEN/FORM A CLOSED LOW AS IT MOVES SOUTHEAST OF THE AREA TONIGHT TOWARD IN/MI BORDER BY FRI 12Z. AT THE SURFACE...HIGH PRESSURE WILL BE BUILDING INTO THE AREA WITH DRYING/NORTHERLY FLOW. THIS IS EXPECTED TO DRY UP/PUSH ANY LINGERING SHRA ACTIVITY SOUTHEAST OF THE AREA BY MIDNIGHT...WITH CLEARING SKIES FROM NORTHWEST TO SOUTHEAST. LOOK FOR LOWS IN THE LOWER/MID 50S WITH POCKETS OF MID/UPPER 40S IN THE CRANBERRY BOG AREAS OF CENTRAL WI. ON FRIDAY...CLOSED MID-LEVEL AND DEEP SURFACE LOW WILL HANG UP OVER SOUTHERN LOWER MI AS HIGH PRESSURE CONTINUES TO BUILD INTO OUR AREA. DECENT DRYING NORTHERLY FLOW WILL RESULT ACROSS THE AREA. MAY SEE SOME CUMULUS BUILD UP ACROSS THE EASTERN PORTION OF THE AREA DUE TO CLOSER PROXIMITY OF COLDER/CYCLONIC FLOW ALOFT. TRENDED DEW POINTS LOWER DUE TO ANTICIPATED DEEPER MIXING TO 825MB PER THE NAM BUFKIT SOUNDING. HIGH TEMPERATURES WILL CONTINUE TO BE A BIT ON THE COOLER THAN NORMAL SIDE IN THE 70S. HIGH PRESSURE WILL SETTLE OVERHEAD FRIDAY NIGHT WITH THE RIDGE AXIS OVER AT LEAST THE WESTERN HALF OF THE FORECAST AREA. LIGHT WINDS/CLEAR SKIES AND WATER TEMPERATURES SITTING IN THE UPPER 70S WILL LIKELY LEAD TO SOME RIVER VALLEY FOG TOWARD MORNING. OTHERWISE...OVERNIGHT LOWS WILL BE QUITE COOL IN THE 40S. HIGH PRESSURE CONTINUES TO BE IN CONTROL ACROSS THE AREA THROUGH SATURDAY FOR DRY CONDITION WITH HIGHS IN THE MID/UPPER 70S. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY 241 AM CDT THU AUG 9 2012 LATEST GFS/ECMWF I FAIRLY DECENT AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. BOTH SHOW A WEAK MID-LEVEL TROUGH MOVING EAST OUT OF THE DAKOTAS/CENTRAL PLAINS TOWARD THE AREA SATURDAY NIGHT THROUGH SUNDAY NIGHT FOR A SMALL CHANCE OF SHOWER/THUNDERSTORMS. A MORE SIGNIFICANT LOW PRESSURE SYSTEM IS SLATED TO MOVE EAST OUT OF THE PACIFIC NORTHWEST INTO THE REGION BY WEDNESDAY. WARM AIR ADVECTION IN ADVANCE OF THIS SYSTEM WILL GIVE THE AREA INCREASING SHOWER/THUNDERSTORM CHANCES FROM TUESDAY INTO WEDNESDAY. OTHERWISE...LOOK FOR TEMPERATURES RETURN TO NEAR OR SLIGHTLY ABOVE NORMAL IN THE EXTENDED WITH HIGHS WARMING FROM THE 70S ON SUNDAY TO WELL INTO THE 80S TUESDAY AND WEDNESDAY. && .AVIATION...THROUGH 18Z FRIDAY 109 PM CDT THU AUG 9 2012 FORECAST CONCERNS THIS PERIOD ARE PRECIPITATION CHANCES THIS AFTERNOON...THEN STRATUS/FOG POTENTIAL OVERNIGHT. CLOSED UPPER LEVEL LOW CURRENTLY NEAR DULUTH SLIDING SOUTH...AND SCATTERED SHOWERS/STORMS DEVELOPING OUT AHEAD OF SURFACE COLD FRONT MOVING THROUGH. EXPECT HIGHEST CHANCE OF SHOWERS/STORMS AT KRST/KLSE THROUGH EARLY EVENING...THEN AS DRIER AIR WORKS IN AND LOSS OF DAYTIME HEATING...PRECIP WILL GRADUALLY SUBSIDE. MVFR CLOUDS WILL HANG ON AT KLSE THIS AFTERNOON...BEING CLOSER TO UPPER LOW AND STEADY EAST WINDS. AT KRST...EXPECTING A RISE TO VFR CEILINGS THIS AFTERNOON. ATTENTION TURNS TO WHETHER AMPLE LOW-LEVEL MOISTURE IN THE BOUNDARY LAYER WILL LEAD TO FOG AND/OR STRATUS OVERNIGHT. FORECAST SOUNDINGS SUGGEST BOUNDARY LAYER WINDS TO REMAIN HIGH ENOUGH FOR MIXING...EXCEPT FOR RIGHT NEAR SURFACE WHERE INVERSION DEVELOPS...TRAPPING ANY REMAINING MOISTURE. GIVEN CLOUDS/RAIN TODAY AND EXPECTED CLEARING TONIGHT...CONTINUED MVFR CONDITIONS AT BOTH TAF SITES. THERE IS POTENTIAL CONDITIONS COULD LOWER TO IFR...BUT CONFIDENCE ISN/T HIGH ENOUGH TO INCLUDE AT THIS POINT. && .ARX WATCHES/WARNINGS/ADVISORIES... 241 AM CDT THU AUG 9 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...ZT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
711 AM CDT THU AUG 9 2012 .SHORT TERM...TODAY THROUGH SATURDAY 241 AM CDT THU AUG 9 2012 MAIN CONCERNS INCLUDE RAIN CHANCES TODAY INTO THIS EVENING/FOG FRIDAY NIGHT/TEMPERATURES THROUGH THE PERIOD. LATEST WATER VAPOR IMAGERY/RAP 500MB ANALYSIS SHOWING A MID-LEVEL SHORTWAVE TROUGH MOVING SOUTHEAST ACROSS SOUTHERN WI/EASTERN IA. ANOTHER MORE VIGOROUS SHORTWAVE WAS MOVING SOUTH THROUGH WESTERN ONTARIO/ARROWHEAD REGION OF MN. SOUTHERN SHORTWAVE TROUGH DEFORMATION AREA WAS PRODUCING SOME 700MB FRONTOGENETIC FORCING AND RESULTING IN SCATTERED -SHRA ACTIVITY MAINLY EAST OF THE MISSISSIPPI RIVER. RAP SHOWS THIS FRONTOGENESIS WEAKENING OVER THE NEXT FEW HOURS...AND RADAR MOSAIC ALREADY SHOWING DISSIPATION OF THE SHRA ACTIVITY. MEANWHILE...THE TROUGH DROPPING SOUTH THROUGH ONTARIO/NORTHERN MN WAS PRODUCING A MORE ORGANIZED BAND OF SHRA/ISOLD THUNDER IN GOOD 700-300MB PV-ADVECTION PER THE RAP. OTHERWISE...SKIES ACROSS THE AREA WERE MOSTLY CLOUDY WITH TEMPERATURES IN THE 60S. LATEST NCEP MODELS/SREF REMAIN IN GOOD AGREEMENT THROUGH THE SHORT TERM PERIOD. FOR TODAY...WILL BE WATCHING THE WAVE OVER ONTARIO/NORTHERN MN DROP SOUTHEAST ACROSS THE AREA. INCREASING PV-ADVECTION/STEEPENING LAPSE RATES ACROSS THE AREA WILL LEAD TO MORE SHOWER/THUNDER DEVELOPMENT. BEST FORCING APPEARS TO BE EAST OF THE MISSISSIPPI...SO TRENDED POPS HIGHER THERE. IN ADDITION...THE NAM INDICATING 0-3KM MUCAPE INCREASING INTO THE 1000-1500J/KG RANGE BY NOON WITH BULK SHEAR IN THE 15 TO 30KT RANGE FOR PERHAPS SOME LINEAR ORGANIZATION OF THE CONVECTION. WITH THIS IN MIND...ALONG WITH COLDER AIR ALOFT AND LOWERING WET BULB ZERO HEIGHTS...WILL HAVE TO WATCH FOR ISOLATED SEVERE THREAT TODAY WITH HAIL AND WIND BEING THE MAIN THREATS. OTHERWISE...TEMPERATURES WILL BE A BIT COOLER WITH THE TROUGH/SCATTERED CONVECTION. ANTICIPATING HIGHS TODAY RANGING FROM THE UPPER 60S ACROSS NORTH CENTRAL WI...TO THE LOWER/MID 70S ELSEWHERE. LOOK FOR THE TROUGH TO DEEPEN/FORM A CLOSED LOW AS IT MOVES SOUTHEAST OF THE AREA TONIGHT TOWARD IN/MI BORDER BY FRI 12Z. AT THE SURFACE...HIGH PRESSURE WILL BE BUILDING INTO THE AREA WITH DRYING/NORTHERLY FLOW. THIS IS EXPECTED TO DRY UP/PUSH ANY LINGERING SHRA ACTIVITY SOUTHEAST OF THE AREA BY MIDNIGHT...WITH CLEARING SKIES FROM NORTHWEST TO SOUTHEAST. LOOK FOR LOWS IN THE LOWER/MID 50S WITH POCKETS OF MID/UPPER 40S IN THE CRANBERRY BOG AREAS OF CENTRAL WI. ON FRIDAY...CLOSED MID-LEVEL AND DEEP SURFACE LOW WILL HANG UP OVER SOUTHERN LOWER MI AS HIGH PRESSURE CONTINUES TO BUILD INTO OUR AREA. DECENT DRYING NORTHERLY FLOW WILL RESULT ACROSS THE AREA. MAY SEE SOME CUMULUS BUILD UP ACROSS THE EASTERN PORTION OF THE AREA DUE TO CLOSER PROXIMITY OF COLDER/CYCLONIC FLOW ALOFT. TRENDED DEW POINTS LOWER DUE TO ANTICIPATED DEEPER MIXING TO 825MB PER THE NAM BUFKIT SOUNDING. HIGH TEMPERATURES WILL CONTINUE TO BE A BIT ON THE COOLER THAN NORMAL SIDE IN THE 70S. HIGH PRESSURE WILL SETTLE OVERHEAD FRIDAY NIGHT WITH THE RIDGE AXIS OVER AT LEAST THE WESTERN HALF OF THE FORECAST AREA. LIGHT WINDS/CLEAR SKIES AND WATER TEMPERATURES SITTING IN THE UPPER 70S WILL LIKELY LEAD TO SOME RIVER VALLEY FOG TOWARD MORNING. OTHERWISE...OVERNIGHT LOWS WILL BE QUITE COOL IN THE 40S. HIGH PRESSURE CONTINUES TO BE IN CONTROL ACROSS THE AREA THROUGH SATURDAY FOR DRY CONDITION WITH HIGHS IN THE MID/UPPER 70S. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY 241 AM CDT THU AUG 9 2012 LATEST GFS/ECMWF I FAIRLY DECENT AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. BOTH SHOW A WEAK MID-LEVEL TROUGH MOVING EAST OUT OF THE DAKOTAS/CENTRAL PLAINS TOWARD THE AREA SATURDAY NIGHT THROUGH SUNDAY NIGHT FOR A SMALL CHANCE OF SHOWER/THUNDERSTORMS. A MORE SIGNIFICANT LOW PRESSURE SYSTEM IS SLATED TO MOVE EAST OUT OF THE PACIFIC NORTHWEST INTO THE REGION BY WEDNESDAY. WARM AIR ADVECTION IN ADVANCE OF THIS SYSTEM WILL GIVE THE AREA INCREASING SHOWER/THUNDERSTORM CHANCES FROM TUESDAY INTO WEDNESDAY. OTHERWISE...LOOK FOR TEMPERATURES RETURN TO NEAR OR SLIGHTLY ABOVE NORMAL IN THE EXTENDED WITH HIGHS WARMING FROM THE 70S ON SUNDAY TO WELL INTO THE 80S TUESDAY AND WEDNESDAY. && .AVIATION...TODAY AND TONIGHT 711 AM CDT THU AUG 9 2012 INVERTED TROUGH EXTENDING NORTH FROM THE SURFACE LOW OVER MO/IL REACHES UP RIGHT ALONG THE MISSISSIPPI NEAR KLSE. MOISTURE POOLING NEAR THE BOUNDARY HELPING TO FUEL LOW STRATUS ACROSS NORTHERN IA...SOUTHEAST MN...AND WESTERN/NORTHERN WI. KRST OBSERVATIONS HAVE RECENTLY GONE DOWN TO LIFR AND ANTICIPATE THIS TO LINGER FOR A FEW HOURS THIS MORNING. SLOW IMPROVEMENT TO MVFR BY 16Z IS ANTICIPATED. KLSE IS A BIT CLOSER TO THE WIND SHIFT AND THUS THE LOWEST CLOUD IS NOT IMPACTING THE AIRPORT DIRECTLY. MVFR CONDITIONS SHOULD PREVAIL...BUT PERIODS OF IFR/LIFR POSSIBLE FOR A FEW HOURS THIS MORNING. UPPER LEVEL SHORT WAVE TROUGH APPROACHING THUNDER BAY THIS MORNING WILL DROP SOUTHEAST INTO THE GREAT LAKES BY TONIGHT. ASSOCIATED SURFACE LOW AND COLD FRONT ARE EXPECTED TO SWEEP THROUGH THE REGION AS WELL. THIS SHOULD BRING ANOTHER RISK FOR SHRA THIS AFTERNOON. BEST FORCING APPEARS TO BE EAST OF THE MISSISSIPPI SO DO NOT ANTICIPATE A LARGE THREAT FOR THUNDER AT KLSE. THUS HAVE LEFT IT OUT OF THE TAF AT THIS TIME. FINAL CONCERN IS FOR FOG TONIGHT AS THE SYSTEM DEPARTS THE AREA AND HIGH PRESSURE BUILDS IN. RIDGE AXIS WILL NOT MAKE IT COMPLETELY INTO THE AREA...SO WINDS MAY STAY UP JUST ENOUGH TO KEEP THE DENSE FOG TO FORM. BUT I DO ANTICIPATE AT LEAST SOME LIGHT FOG/MIST TO DEVELOP...SO ADDED TO THE TAFS. LATER SHIFTS WILL MONITOR THE CLEARING TREND THIS EVENING...AND PROGRESS OF THE RIDGE AXIS TONIGHT...TO DETERMINE IF CHANGES TO THE FOG FORECAST ARE NEEDED. && .ARX WATCHES/WARNINGS/ADVISORIES... 241 AM CDT THU AUG 9 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...MW
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
241 AM CDT THU AUG 9 2012 .SHORT TERM...TODAY THROUGH SATURDAY 241 AM CDT THU AUG 9 2012 MAIN CONCERNS INCLUDE RAIN CHANCES TODAY INTO THIS EVENING/FOG FRIDAY NIGHT/TEMPERATURES THROUGH THE PERIOD. LATEST WATER VAPOR IMAGERY/RAP 500MB ANALYSIS SHOWING A MID-LEVEL SHORTWAVE TROUGH MOVING SOUTHEAST ACROSS SOUTHERN WI/EASTERN IA. ANOTHER MORE VIGOROUS SHORTWAVE WAS MOVING SOUTH THROUGH WESTERN ONTARIO/ARROWHEAD REGION OF MN. SOUTHERN SHORTWAVE TROUGH DEFORMATION AREA WAS PRODUCING SOME 700MB FRONTOGENETIC FORCING AND RESULTING IN SCATTERED -SHRA ACTIVITY MAINLY EAST OF THE MISSISSIPPI RIVER. RAP SHOWS THIS FRONTOGENESIS WEAKENING OVER THE NEXT FEW HOURS...AND RADAR MOSAIC ALREADY SHOWING DISSIPATION OF THE SHRA ACTIVITY. MEANWHILE...THE TROUGH DROPPING SOUTH THROUGH ONTARIO/NORTHERN MN WAS PRODUCING A MORE ORGANIZED BAND OF SHRA/ISOLD THUNDER IN GOOD 700-300MB PV-ADVECTION PER THE RAP. OTHERWISE...SKIES ACROSS THE AREA WERE MOSTLY CLOUDY WITH TEMPERATURES IN THE 60S. LATEST NCEP MODELS/SREF REMAIN IN GOOD AGREEMENT THROUGH THE SHORT TERM PERIOD. FOR TODAY...WILL BE WATCHING THE WAVE OVER ONTARIO/NORTHERN MN DROP SOUTHEAST ACROSS THE AREA. INCREASING PV-ADVECTION/STEEPENING LAPSE RATES ACROSS THE AREA WILL LEAD TO MORE SHOWER/THUNDER DEVELOPMENT. BEST FORCING APPEARS TO BE EAST OF THE MISSISSIPPI...SO TRENDED POPS HIGHER THERE. IN ADDITION...THE NAM INDICATING 0-3KM MUCAPE INCREASING INTO THE 1000-1500J/KG RANGE BY NOON WITH BULK SHEAR IN THE 15 TO 30KT RANGE FOR PERHAPS SOME LINEAR ORGANIZATION OF THE CONVECTION. WITH THIS IN MIND...ALONG WITH COLDER AIR ALOFT AND LOWERING WET BULB ZERO HEIGHTS...WILL HAVE TO WATCH FOR ISOLATED SEVERE THREAT TODAY WITH HAIL AND WIND BEING THE MAIN THREATS. OTHERWISE...TEMPERATURES WILL BE A BIT COOLER WITH THE TROUGH/SCATTERED CONVECTION. ANTICIPATING HIGHS TODAY RANGING FROM THE UPPER 60S ACROSS NORTH CENTRAL WI...TO THE LOWER/MID 70S ELSEWHERE. LOOK FOR THE TROUGH TO DEEPEN/FORM A CLOSED LOW AS IT MOVES SOUTHEAST OF THE AREA TONIGHT TOWARD IN/MI BORDER BY FRI 12Z. AT THE SURFACE...HIGH PRESSURE WILL BE BUILDING INTO THE AREA WITH DRYING/NORTHERLY FLOW. THIS IS EXPECTED TO DRY UP/PUSH ANY LINGERING SHRA ACTIVITY SOUTHEAST OF THE AREA BY MIDNIGHT...WITH CLEARING SKIES FROM NORTHWEST TO SOUTHEAST. LOOK FOR LOWS IN THE LOWER/MID 50S WITH POCKETS OF MID/UPPER 40S IN THE CRANBERRY BOG AREAS OF CENTRAL WI. ON FRIDAY...CLOSED MID-LEVEL AND DEEP SURFACE LOW WILL HANG UP OVER SOUTHERN LOWER MI AS HIGH PRESSURE CONTINUES TO BUILD INTO OUR AREA. DECENT DRYING NORTHERLY FLOW WILL RESULT ACROSS THE AREA. MAY SEE SOME CUMULUS BUILD UP ACROSS THE EASTERN PORTION OF THE AREA DUE TO CLOSER PROXIMITY OF COLDER/CYCLONIC FLOW ALOFT. TRENDED DEW POINTS LOWER DUE TO ANTICIPATED DEEPER MIXING TO 825MB PER THE NAM BUFKIT SOUNDING. HIGH TEMPERATURES WILL CONTINUE TO BE A BIT ON THE COOLER THAN NORMAL SIDE IN THE 70S. HIGH PRESSURE WILL SETTLE OVERHEAD FRIDAY NIGHT WITH THE RIDGE AXIS OVER AT LEAST THE WESTERN HALF OF THE FORECAST AREA. LIGHT WINDS/CLEAR SKIES AND WATER TEMPERATURES SITTING IN THE UPPER 70S WILL LIKELY LEAD TO SOME RIVER VALLEY FOG TOWARD MORNING. OTHERWISE...OVERNIGHT LOWS WILL BE QUITE COOL IN THE 40S. HIGH PRESSURE CONTINUES TO BE IN CONTROL ACROSS THE AREA THROUGH SATURDAY FOR DRY CONDITION WITH HIGHS IN THE MID/UPPER 70S. .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY 241 AM CDT THU AUG 9 2012 LATEST GFS/ECMWF I FAIRLY DECENT AGREEMENT THROUGH THE EXTENDED FORECAST PERIOD. BOTH SHOW A WEAK MID-LEVEL TROUGH MOVING EAST OUT OF THE DAKOTAS/CENTRAL PLAINS TOWARD THE AREA SATURDAY NIGHT THROUGH SUNDAY NIGHT FOR A SMALL CHANCE OF SHOWER/THUNDERSTORMS. A MORE SIGNIFICANT LOW PRESSURE SYSTEM IS SLATED TO MOVE EAST OUT OF THE PACIFIC NORTHWEST INTO THE REGION BY WEDNESDAY. WARM AIR ADVECTION IN ADVANCE OF THIS SYSTEM WILL GIVE THE AREA INCREASING SHOWER/THUNDERSTORM CHANCES FROM TUESDAY INTO WEDNESDAY. OTHERWISE...LOOK FOR TEMPERATURES RETURN TO NEAR OR SLIGHTLY ABOVE NORMAL IN THE EXTENDED WITH HIGHS WARMING FROM THE 70S ON SUNDAY TO WELL INTO THE 80S TUESDAY AND WEDNESDAY. && .AVIATION...THROUGH 06Z FRIDAY 1156 PM CDT WED AUG 8 2012 COMPLICATED WEATHER SYSTEM TO AFFECT THE TAFS THROUGH THE PERIOD. MOISTURE CONVERGENCE IN THE LOW-LEVELS IS LEADING TO SHOWERS JUST NORTH OF THE TAF SITES OVERNIGHT. WITHIN THIS SHOWER BAND CIGS ARE MVFR AND AS SUNRISE APPROACHES...IFR CAN BE EXPECTED. THIS AREA OF CLOUD WILL SHIFT INTO THE TAFS TO CAUSE THE MVFR/IFR OVERNIGHT. AS THE DAYTIME CONTINUES...CIGS SHOULD IMPROVE. A VIGOROUS WEATHER SYSTEM WILL SHIFT THROUGH WI DURING THE DAY BUT KLSE IS EXPECTED TO BE FAR ENOUGH WEST TO NOT SEE TSRA CHANCES. HOWEVER...THIS MAY NEED TO BE ADDED TO FUTURE FORECASTS SHOULD TSRA THREAT INCREASE. && .ARX WATCHES/WARNINGS/ADVISORIES... 241 AM CDT THU AUG 9 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...BAUMGARDT
AREA FORECAST DISCUSSION
NWS NEW YORK NY
419 AM EDT SAT AUG 11 2012 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL MOVE TOWARDS THE REGION TODAY WITH A LOW DEVELOPING ALONG IT TONIGHT AS IT WEAKENS IN THE REGION. THE FRONT MOVES ACROSS THE WHOLE REGION BY SUNDAY EVENING. HIGH PRESSURE BUILDS INTO THE REGION FOR THE START OF THE NEW WEEK...THEN UNSETTLED WEATHER RETURNS LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... EQUIVALENT BAROTROPIC STRUCTURE TO LOW NEAR LAKE HURON. THIS LOW SLOWLY WEAKENS AND MOVES NORTH...FARTHER AWAY FROM ITS ASSOCIATED FRONTAL SYSTEM TO THE SOUTH AND EAST. THE TIMING REPRESENTS A SLOWER TIMING OF THE FRONTAL MOVEMENT. THE AREA STAYS IN THE WARM SECTOR THROUGH THE DAY WITH EASTERN SECTIONS CLOSER TO LOW LEVEL JET DEVELOPMENT ASSOCIATED WITH SECONDARY CYCLOGENESIS NEAR DELMARVA. A COLD FRONT AT THE SURFACE SLOWLY APPROACHES FROM THE WEST AND MOVES INTO THE AREA...WEAKENING AS IT DOES SO. THERE WILL BE EMBEDDED SHORTWAVES MOVING THROUGH ALOFT ON A SSW SYNOPTIC FLOW WITH THE LOCAL REGION NEAR THE SOUTHERN END OF A REGION OF DECENT MID LEVEL Q VECTOR CONVERGENCE. PW VALUES REMAIN IN GENERAL 1.8 TO 2 INCH RANGE FOR CITY AND EASTERN SECTIONS. NORTH AND WEST OF THE CITY...THERE ARE SIGNS SOME DRIER AIR WILL TRY TO WORK INTO THE ATMOSPHERE...ALLOWING FOR PW VALUES TO DROP A FEW TENTHS OF AN INCH BY THE END OF THE AFTERNOON INTO THE EVENING. 2/3 MET AND 1/3 MAV FOR MAX TEMPS TODAY. GREATER WEIGHT WITH COOLER GUIDANCE WITH ABUNDANT CLOUDS AND HIGHER POPS EXPECTED. ANY SHOWERS AND THUNDERSTORM COULD PRODUCE HEAVY DOWNPOURS AS WELL AS GUSTY WINDS WITH BULK SHEAR 0-6KM OF AROUND 30 KT. THERE IS A MODERATE RISK FOR RIP CURRENTS ALONG THE SOUTH SHORE OF LONG ISLAND THIS AFTERNOON AND EVENING. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... COLD FRONT WILL BE MOVING THROUGH BY LATE SUNDAY AFTERNOON AT LEAST ACROSS THE WESTERN HALF OF THE CWA. AGAIN...A SLOWER TIMING OF THE FRONT HAS BEEN CONVEYED BY MUCH OF THE NUMERICAL GUIDANCE. POPS INCREASED FROM PREVIOUS FORECAST WITH SOME LINGER SHOWERS AND THUNDERSTORMS TONIGHT. THE COVERAGE WILL BE HIGHEST OUT EAST...WHERE BETTER DYNAMICS WILL BE. BLEND OF MET...MAV...AND NAM12 SFC TEMPS FOR MIN TEMPS TONIGHT WITHOUT MUCH DIURNAL TEMP RANGE EXPECTED. SOUTHERLY FLOW WILL BE STILL IN PLACE. A WAVE OF LOW PRESSURE DEVELOPS ALONG THE COLD FRONT WHICH WILL BE MOVING INTO THE REGION. 2/3 MAV AND 1/3 MET FOR MAX TEMPS ON SUN. AGAIN...THIS IS FAVORING THE COOLER GUIDANCE. IT DOES APPEAR THIS WILL BE A WARMER DAY FOR WESTERN SECTIONS AS DRIER AIR MOVES FARTHER EAST IN THE AFTERNOON HOURS BEHIND THE COLD FRONT. POPS FOR SHOWERS DIMINISH AS WELL FROM WEST TO EAST. THUNDERSTORMS WILL BE MORE ISOLATED GIVEN THE LOWER CAPE ACROSS THE REGION OF LESS THAN 1000 J/KG FOR MOST LOCATIONS. FOR MONDAY....COLD FRONT EAST OF REGION AND MORE STABLE AIR IN PLACE AS HIGH PRESSURE BUILDS IN. WARMER TEMPS EXPECTED WITH WARMER MET GUIDANCE CHOSEN. FLOW AT SFC TURNS MORE WESTERLY WITH DRIER AIR WORKING ITS WAY IN...HELPING INCREASE DIURNAL WARMTH. MAV/MET BLEND USED FOR MIN TEMPS MONDAY NIGHT WITH NEAR NORMAL TEMPS EXPECTED AS HIGH PRESSURE MOVES OFFSHORE. && .LONG TERM /TUESDAY THROUGH FRIDAY/... WITH THE HIGH MOVING OFFSHORE MONDAY NIGHT AND LOW PRES TRACKING THROUGH THE GREAT LAKES AND OHIO VALLEY...A WARM FRONT WILL LIFT NORTH INTO THE REGION MONDAY NIGHT/TUESDAY MORNING. SOME SHOWERS/THUNDERSTORMS EXPECTED WITH ITS PASSAGE. AS THE LOW TRACKS INTO EASTERN CANADA...A SECONDARY LOW WILL FORM OVER THE DELMARVA AREA ON TUESDAY...AND THIS SYSTEM WILL KEEP SHOWERS AND THUNDERSTORMS IN THE FORECAST THROUGH WEDNESDAY. WEAK HIGH PRES WILL MOVE THROUGH THE REGION THURSDAY...THEN ANOTHER SYSTEM WILL IMPACT THE AREA LATE IN THE WEEK. THERE ARE INCONSISTENCIES AMONG THE MODELS...RESULTING IN A LOW CONFIDENCE FORECAST FOR THE LONG TERM PERIOD. HPC GUIDANCE WAS CLOSELY FOLLOWED AS A RESULT. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... ISOLATED TO SCATTERED CONVECTION LIKELY TO STAY EAST OF THE TERMINALS OVERNIGHT WITH THE EXCEPTION OF KGON. LOW CONFIDENCE FORECAST. HAVE FOLLOWED PERSISTENCE FROM THE LAST FEW NIGHT WITH AREAS OF MVFR TO LOCALLY IFR THROUGH 12Z OR SO WITH MOIST LOW LEVELS. ANOTHER WEAK BOUNDARY IS FORECAST TO LIFT N OF THE AREA LATER THIS MORNING AND AFTERNOON. SHOWERS AND TSTMS LIKELY DEVELOP AGAIN AHEAD OF IT AND CURRENT TIMING MAY NOT BE EARLY ENOUGH. LATEST HRRR MOVED UP THE TIMING FROM 15Z BACK TO 13Z. IF THIS TREND CONTINUES AND START TO SEE DEVELOPMENT TO THE S...WILL NEED TO AMEND TIMING IN 06Z TAFS. CIGS WILL LIKELY VARY FROM VFR TO MVFR/IFR WITH ANY CONVECTION. COLD FRONT ADVANCING FROM THE WEST WILL ALSO TRIGGER SCT CONVECTION DURING THE AFTN. MORNING ACTIVITY WILL DETERMINE WHETHER AIRMASS CAN RECOVER FOR MORE STORMS IN THE AFTN. HAVE CONTINUED WITH PROB30. OUTLOOK FOR 06Z SUNDAY THROUGH WEDNESDAY... .SAT NIGHT...AREAS OF MVFR TO IFR IN FOG/STRATUS. .SUN-TUE MORN...VFR. .TUE AFTN-WED...SCT SHOWERS AND TSTMS. && .MARINE... WEAK WARM FRONTAL BOUNDARY LIFTS N OF THE WATERS LATER THIS MORNING/AFTN. MEANWHILE...A COLD FRONT AND WAVE OF LOW PRES WILL APPROACH FROM THE WEST AND SLOWLY MOVE ACROSS THE AREA SUN AND SUN NIGHT. TIGHTENING PRES GRADIENT TODAY WITH SLY WINDS 10-20 KT ON THE WATERS...HIGHEST ON THE OCEAN. GUSTS ON THE OCEAN WATERS MAY FALL SHORT OF ADVSY LEVELS THIS AFTN...BUT SEAS WILL REMAIN BETWEEN 5 AND 7 FT THROUGH TONIGHT. SCA REMAINS IN PLACE AS A RESULT. MARGINAL SEAS MAY LINGER INTO SUNDAY MORNING...MAINLY ON EASTERN OCEAN WATERS...BUT DO NOT HAVE THE CONFIDENCE TO EXTEND INTO THE THIRD PERIOD AT THIS POINT...ESPECIALLY SINCE WW3 HAS BEEN RUNNING HIGH ALL SEASON. HIGH PRES BUILDS IN FOR MONDAY INTO TUE...THEN ANOTHER FRONTAL SYSTEM WITH UNSETTLED WEATHER RETURNS FOR THE MIDDLE OF THE WEEK. SUB-ADVSY CONDS ARE EXPECTED DURING THIS TIME. && .HYDROLOGY... STILL LOOKING AT A HEAVY RAIN THREAT WITH PWATS NEAR 1.8 TO 2 INCHES FOR TODAY AND TONIGHT...ESPECIALLY FOR EASTERN SECTIONS OF THE FORECAST REGION. ADDITIONAL RAINFALL TOTALS THROUGH SUNDAY ARE BASIN AVERAGED FROM 1/2 TO 1 INCH. HIGHER AMOUNTS WILL BE POSSIBLE UP TO 2 INCHES HERE THOUGH. SIMILAR TO YESTERDAY...MINOR FLOODING SEEMS TO BE MAIN THREAT WITH ISOLATED FLASH FLOODING POSSIBLE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ350-353-355. && $$ SYNOPSIS...JM NEAR TERM...JM SHORT TERM...JM LONG TERM...MPS AVIATION...24 MARINE...24 HYDROLOGY...JM
AREA FORECAST DISCUSSION
NWS NEW YORK NY
246 AM EDT SAT AUG 11 2012 .SYNOPSIS... A SLOW MOVING COLD FRONT APPROACHES FROM THE WEST THROUGH THE FIRST HALF OF THE WEEKEND...THEN PASSES TO THE EAST SUNDAY MORNING. HIGH PRESSURE BUILDS INTO THE REGION FOR THE START OF THE NEW WEEK...THEN UNSETTLED WEATHER RETURNS LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... LOW PRESSURE OVER THE OHIO VALLEY WILL CONTINUE TO SLOWLY RETROGRADE TOWARDS LAKE HURON INTO EARLY SATURDAY MORNING. THIS WILL BEGIN A SLIGHT WEAKENING TREND AS THE UPPER LEVEL LOW WILL BE DIRECTLY OVERHEAD...LIMITING FAVORABLE VORTICITY AND TEMPERATURE ADVECTIONS WITH AN EQUIVALENT BAROTROPIC STRUCTURE. THE ASSOCIATED FRONTAL SYSTEM TO THE SOUTH AND EAST WILL BECOME SLOWER IN MOVEMENT. THE AREA REMAINS IN THE WARM SECTOR WITH HIGH PRECIPITABLE WATER VALUES OF 1.7 TO 2 INCHES AND HIGHEST CAPE VALUES ON ORDER OF 1000-1500 J/KG ALONG PORTIONS OF LONG ISLAND AND HIGHER TO THE SOUTH. NOT EXPECTING MUCH FURTHER DROP IN TEMPS AND THESE AS WELL AS DEWPOINTS ARE ON TRACK. LOWS IN THE UPPER 60S TO LOWER 70S FOR MOST PLACES WITH PATCHY FOG EXPECTED TOWARDS MORNING WITH NEARLY SATURATED AIRMASS IN PLACE. LOOKING FOR CONVECTION TO BECOME GENERALLY ISOLATED UNTIL ANOTHER MID LEVEL IMPULSE ARRIVES TOWARDS SATURDAY MORNING AS THE BROKEN LINE OF CONVECTION FROM THE WEST APPROACHES THE CWA. AT THE SFC...THIS WILL BE SEEN AS A WEAK WARM FRONT ASSOCIATED WITH SECONDARY LOW DEVELOPMENT TOWARDS THE DELMARVA. WITH HIGH PW VALUES...KEPT MENTION OF HEAVY RAIN POTENTIAL BY SATURDAY MORNING. && .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY NIGHT/... SOME QUESTIONS AS TO HOW MUCH PRECIP WILL MAKE IT TO THE LOCAL AREA DURING THE DAY ON SATURDAY. WITH THE COLD FRONT WEST OF THE AREA TRACKING EAST AND LOW PRES MOVING ALONG THE COAST...SHOWERS WILL DEVELOP ONCE AGAIN OVER THE AREA...BUT IT LOOKS LIKE THE BULK OF THE PRECIP COULD BE CONFINED TO EASTERN ZONES AND OVER THE OCEAN. WILL CARRY LIKELY POPS FOR THE EASTERN ZONES AND CHANCE OVER THE WESTERN ZONES FOR SATURDAY AND SATURDAY NIGHT AS THE FRONT SLOWLY MOVES THROUGH THE REGION. ON SUNDAY...THE FRONT SHOULD BE THROUGH WESTERN ZONES...AND WILL EXPECT MAINLY DRY CONDS FOR WESTERN ZONES SATURDAY NIGHT AND SUNDAY...AND LOW CHANCE POPS AHEAD OF THE FRONT OVER THE EASTERN ZONES. BY SUNDAY NIGHT...PRECIP WILL BE EAST OF THE AREA AND HIGH PRES TO THE WEST WILL NOSE ITS WAY INTO THE REGION FROM THE WEST. CLOUD COVER SHOULD KEEP INSTABILITY PARAMETERS LOW...AND THUNDERSTORMS SHOULD BE ISOLATED TO SCATTERED...PRODUCING LOCALLY HEAVY RAIN AND GUSTY WINDS. THERE IS A MODERATE RISK FOR RIP CURRENTS ALONG THE SOUTH SHORE OF LONG ISLAND IN THE AFTERNOON AND EVENING. && .LONG TERM /MONDAY THROUGH FRIDAY/... HIGH PRES BUILDS INTO THE REGION MONDAY AND MOVES OFFSHORE MONDAY NIGHT. DRY AND MILD CONDS WITH TEMPS RUNNING A FEW DEGREES ABOVE NORMAL...TOPPING OUT IN THE MID TO UPPER 80S. WITH THE HIGH MOVING OFFSHORE MONDAY NIGHT AND LOW PRES TRACKING THROUGH THE GREAT LAKES AND OHIO VALLEY...A WARM FRONT WILL LIFT NORTH INTO THE REGION MONDAY NIGHT/TUESDAY MORNING. SOME SHOWERS/THUNDERSTORMS EXPECTED WITH ITS PASSAGE. AS THE LOW TRACKS INTO EASTERN CANADA...A SECONDARY LOW WILL FORM OVER THE DELMARVA AREA ON TUESDAY...AND THIS SYSTEM WILL KEEP SHOWERS AND THUNDERSTORMS IN THE FORECAST THROUGH WEDNESDAY. WEAK HIGH PRES WILL MOVE THROUGH THE REGION THURSDAY...THEN ANOTHER SYSTEM WILL IMPACT THE AREA LATE IN THE WEEK. THERE ARE INCONSISTENCIES AMONG THE MODELS...RESULTING IN A LOW CONFIDENCE FORECAST FOR THE LONG TERM PERIOD. HPC GUIDANCE WAS CLOSELY FOLLOWED AS A RESULT. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... ISOLATED TO SCATTERED CONVECTION LIKELY TO STAY EAST OF THE TERMINALS OVERNIGHT WITH THE EXCEPTION OF KGON. LOW CONFIDENCE FORECAST. HAVE FOLLOWED PERSISTENCE FROM THE LAST FEW NIGHT WITH AREAS OF MVFR TO LOCALLY IFR THROUGH 12Z OR SO WITH MOIST LOW LEVELS. ANOTHER WEAK BOUNDARY IS FORECAST TO LIFT N OF THE AREA LATER THIS MORNING AND AFTERNOON. SHOWERS AND TSTMS LIKELY DEVELOP AGAIN AHEAD OF IT AND CURRENT TIMING MAY NOT BE EARLY ENOUGH. LATEST HRRR MOVED UP THE TIMING FROM 15Z BACK TO 13Z. IF THIS TREND CONTINUES AND START TO SEE DEVELOPMENT TO THE S...WILL NEED TO AMEND TIMING IN 06Z TAFS. CIGS WILL LIKELY VARY FROM VFR TO MVFR/IFR WITH ANY CONVECTION. COLD FRONT ADVANCING FROM THE WEST WILL ALSO TRIGGER SCT CONVECTION DURING THE AFTN. MORNING ACTIVITY WILL DETERMINE WHETHER AIRMASS CAN RECOVER FOR MORE STORMS IN THE AFTN. HAVE CONTINUED WITH PROB30. OUTLOOK FOR 06Z SUNDAY THROUGH WEDNESDAY... .SAT NIGHT...AREAS OF MVFR TO IFR IN FOG/STRATUS. .SUN-TUE MORN...VFR. .TUE AFTN-WED...SCT SHOWERS AND TSTMS. && .MARINE... SOUTHERLY FLOW INCREASES TONIGHT AS A WARM FRONT LIFTS NORTH. EXPECTING SUB-SCA WINDS/SEAS ON LI SOUND/NY HARBOR/LI BAYS...BUT A FEW GUSTS TO 20 KT ARE POSSIBLE. ON THE OCEAN...25 KT GUSTS EXPECTED TONIGHT THROUGH SATURDAY...AND SEAS WILL BUILD TO 4-6 FT BEGINNING TONIGHT. SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR TONIGHT THROUGH SATURDAY...AND WILL GO AHEAD AND EXTEND IT THROUGH SATURDAY NIGHT. SEAS MAY REMAIN UP THROUGH SUNDAY BEFORE SLOWLY SUBSIDING FROM WEST TO EAST. UNSETTLED WEATHER EXPECTED ON THE WATERS AS SEVERAL AREAS OF LOW PRES TRACK NORTH ALONG THE COAST. BY SUNDAY NIGHT...COLD FRONT WILL BE EAST OF THE AREA AND HIGH PRES WILL BUILD INTO THE WATERS. DRY CONDS FOR THE START OF THE WEEK...THEN UNSETTLED WEATHER ON TAP FOR THE MIDDLE TO END OF NEXT WEEK. SUB-SCA CONDS EXPECTED FOR THE NEW WEEK. && .HYDROLOGY... MUCH LESS PRECIP EXPECTED IN THE OVERNIGHT HOURS INTO TOMORROW. RAINFALL TOTALS BETWEEN 1/4 AND 3/4 IN ARE POSSIBLE...WITH ISOLATED AREAS POSSIBLY HITTING 1 INCH WITH ANY HEAVIER THUNDERSTORMS. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ350-353-355. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1123 PM MDT FRI AUG 10 2012 .UPDATE... ISSUED AT 539 PM MDT FRI AUG 10 2012 THUNDERSTORMS EARLY THIS EVENING HAVE BEEN CONFINED TO THE PALMER DIVIDE AREA AND FRONT RANGE...SO REMOVED MENTION FOR THE EVENING HOURS. HOWEVER...MODELS SHOW A ROBUST 40-50KT LOW LEVEL JET DEVELOPING OVER THE AREA AFTER 06Z WITH MODEST ELEVATED INSTABILITY OF A FEW HUNDRED J/KG. HRRR SIMULATED REFLECTIVITY AND QPF OUTPUT FROM THE NAM AND GFS SUPPORT ADDING A SLIGHT CHANCE MENTION FOR OVERNIGHT ELEVATED CONVECTION. HARD TO PIN DOWN ANY LOCATION SO JUST BROAD BRUSHED ALL AREAS. THIS ACTIVITY...IF IT DEVELOPS...COULD LINGER INTO SATURDAY MORNING. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 231 PM MDT FRI AUG 10 2012 A WEATHER DISTURBANCE CURRENTLY PRODUCING A FEW THUNDERSTORMS IN SOUTHWEST COLORADO IS EXPECTED TO MOVE INTO THE SOUTHERN COLORADO HIGH COUNTRY AND ADJACENT PLAINS BY THE END OF TODAY THEN SOUTHEAST INTO SOUTHWEST KANSAS BY MIDNIGHT BEFORE CONTINUING SOUTHEAST SATURDAY MORNING. ANOTHER WEATHER SYSTEM AND ASSOCIATED SFC TROUGH WILL BRING ANOTHER SLIGHT CHANCE FOR SHOWERS AND THUNDERSTORMS TO THE AREA SATURDAY AFTERNOON. PRECIPITATION CHANCES TONIGHT WILL BE CONFINED TO AREAS IN EASTERN COLORADO AND SOUTH OF INTERSTATE 70. OVERNIGHT LOWS IN THE UPPER 50S TO LOW 60S. HIGHS ON SATURDAY GENERALLY IN THE 90S. IT SHOULD BE NOTED THAT 850MB TEMPERATURES FROM THE NAM/UKMET SUPPORT READINGS CLOSER TO 100 DEGREES IN THE HILL CITY...MCCOOK AND TRIBUNE AREAS. THE GFS 850MB TEMPERATURES SUPPORT READINGS SEVERAL DEGREES COOLER. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 231 PM MDT FRI AUG 10 2012 MAIN FORECAST CONCERN WILL BE CHANCES FOR PRECIP. ACCOMPANYING THE COLD FRONT SATURDAY NIGHT. SATURDAY EVENING A COLD FRONT WILL BE OVER THE WESTERN THIRD TO HALF OF THE AREA. MODELS DISAGREE WITH THE TIMING OF THE FRONT THROUGH THE NIGHT AS WELL AS AVAILABLE MOISTURE TO WORK WITH. THE NAM/ECMWF HAVE THE FRONT EXITING THE AREA DURING THE LATE EVENING...WHILE THE GFS/SREF HAVE THE FRONT EXITING THE AREA BY EARLY SUNDAY MORNING. FAVORED MORE OF A GFS/SREF SOLUTION SINCE ALMOST ALL OF THE GEFS MEMBERS AGREED WITH THE GFS/SREF TIMING OF THE FRONT. MODELS HAVE MOST OF THE LIFT/INSTABILITY FOCUSED ALONG THE FRONT...SO AM THINKING THE MAJORITY OF THE PRECIPITATION ACTIVITY SHOULD REMAIN TIED TO THE FRONT. 850-700MB FRONTOGENESIS INCREASE DURING THE EVENING ALONG THE FRONT THEN DECLINE AS THE FRONT MOVES SOUTHEAST...SO TRENDED PRECIP. CHANCES UPWARD IN THE EVENING THEN LEVELED THEM OFF DURING THE OVERNIGHT HOURS. WITH 0-6KM SHEAR AROUND 30 KTS...AM THINKING ANY SEVERE WEATHER THREAT SHOULD BE CONFINED TO THE EVENING HOURS WHEN 700-500MB CAPE AND INSTABILITY FROM DAYTIME HEATING ARE BEST. SUNDAY WILL BE DRY AS HIGH PRESSURE BUILDS INTO THE AREA BEHIND THE COLD FRONT. AHEAD OF THE HIGH PRESSURE WINDS WILL BE GUSTY DURING THE DAY...MAINLY EAST OF A BENKELMAN TO GOVE LINE...WITH GUSTS UP TO 35 MPH POSSIBLE WHICH MAY CAUSE FIRE WEATHER CONCERNS. SEE FIRE WEATHER SECTION FOR MORE INFORMATION. THE GUSTS WILL DECLINE DURING THE EARLY EVENING AS MIXING DISSIPATES. DURING THE LATE AFTERNOON INTO THE EVENING MODELS SHOW SOME SURFACE CONVERGENCE OVER THE FAR SOUTHWEST PART OF THE AREA ON THE PERIPHERY OF THE SURFACE RIDGE. HOWEVER 500MB SUBSIDENCE IS ALSO PRESENT OVER THE SAME AREA SO WILL ONLY PLACE IN SILENT CHANCES AT THIS TIME. THE MONDAY THROUGH FRIDAY PERIOD STARTS OUT WITH HIT AND MISS PRECIPITATION CHANCES AS A FEW MINOR UPPER LEVEL DISTURBANCES MOVE OVER THE TRI-STATE AREA. PRECIPITATION CHANCES INCREASE AS AN UPPER LEVEL LONG WAVE TROUGH...THAT MOVES ON SHORE TUESDAY...PASSES OVER THE AREA WEDNESDAY NIGHT AND THURSDAY BRINGING A COLD FRONT WITH IT. PRECIPITATION CHANCES CONTINUE ON FRIDAY AS MINOR UPPER LEVEL DISTURBANCES IN THE FLOW MOVE OVER THE AREA. TEMPERATURES WILL BE NEAR NORMAL WITH HIGHS IN THE LOWER 90S AND LOWS IN THE LOWER/MID 60S AHEAD OF THE COLD FRONT...WITH HIGHS IN THE 80S AND LOWS IN THE MID 50S TO LOWER 60S BEHIND THE FRONT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1119 PM MDT FRI AUG 10 2012 VFR CONDITIONS EXPECTED AT BOTH KGLD AND KMCK THROUGH THE VALID TAF PERIOD. HOWEVER...THERE ARE SOME WILD CARDS IN THE MIX. OVERNIGHT...ISOLATED ELEVATED THUNDERSTORMS WILL DEVELOP. SOME HINT OF THEM ALREADY APPARENT ON RADAR SOUTH OF KGLD. CONFIDENCE IS LOW THAT A THUNDERSTORM WILL DIRECTLY IMPACT EITHER TERMINAL. A LOW CHANCE OF THUNDERSTORMS WILL CONTINUE ON FRIDAY. SURFACE WINDS WILL BE CHANGEABLE THROUGH THE PERIOD AS WELL...WITH GUSTY SOUTH WINDS IN THE MORNING AND AFTERNOON FOLLOWED BY A COLD FRONT AND WIND SHIFT TO THE NORTH FRIDAY NIGHT. && .FIRE WEATHER... ISSUED AT 231 PM MDT FRI AUG 10 2012 SUNDAY AFTERNOON WIND GUSTS UP TO 35 MPH MAY DEVELOP MAINLY IN THE MCCOOK TO HILL CITY AREA. RELATIVE HUMIDITIES WILL FALL TO AROUND 25 PERCENT. THESE CONDITIONS ARE ABOVE OUR FIRE WEATHER CRITERIA...SO AM NOT ANTICIPATING A HAZARD BEING NEEDED AT THIS TIME. HOWEVER THE GUSTY WINDS WILL MAKE ANY FIRE THAT IS BURNING DIFFICULT TO CONTROL. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...024 SHORT TERM...DDT LONG TERM...JTL AVIATION...024 FIRE WEATHER...JTL
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
1147 PM CDT FRI AUG 10 2012 .DISCUSSION... 06Z TAF ISSUANCE. && .AVIATION... FRONTAL BOUNDARY OVER E TX/C LA IGNITED NUMEROUS STRONG TO SEVERE TSRA ACROSS THE REGION...WITH THE LAST REMNANTS DISSIPATED OVER THE NORTHERN ATCHAFALAYA BASIN A COUPLE OF HOURS AGO. THE BOUNDARY HASN`T MOVED MUCH. 00Z NAM12 CONTINUES TO SHOW REDEVELOPMENT BETWEEN 09-15Z ACROSS SC LA...WHICH WOULD AFFECT LFT/ARA DURING THIS TIME. WILL PLACE VCSH WITH A TEMPO GROUP OF SHRA & MVFR VSBY/CEILING 10-14Z. BY 15Z...BELIEVE SHRA WILL PUSH SOUTH OF THE TERMINALS...AS DRIER AIR ALOFT FINALLY FILTERS ACROSS THE REGION. DML && .PREV DISCUSSION... /ISSUED 949 PM CDT FRI AUG 10 2012/ UPDATE... WITH CONVECTION CONTINUING TO DECREASE OVER EAST CENTRAL LOUISIANA...WILL GO AHEAD AND CANCELLED THE REMAINDER OF THE SEVERE THUNDERSTORM WATCH. RUA PREV DISCUSSION... /ISSUED 921 PM CDT FRI AUG 10 2012/ UPDATE... HAVE CANCELLED THE SEVERE THUNDERSTORM WATCH FOR ALL EXCEPT PORTIONS OF EAST CENTRAL LOUISIANA...WHERE STILL SOME STRONG STORMS PERSIST. THE STORMS ARE ALSO ON THE DOWNWARD TREND WITH THE LOSS OF DAYTIME HEATING AND THE REAL GOOD INSTABILITY DECREASING. WILL LIKELY BE ABLE TO CANCEL THE REMAINDER OF THE WATCH BEFORE EXPIRATION TIME. ACTIVITY DEVELOPED AHEAD OF A SOUTHWARD MOVING BOUNDARY THAT DELINEATES...VERY MOIST MARITIME AIR TO THE SOUTH...WITH DRIER CONTINENTAL AIR TO THE NORTH. THIS BOUNDARY WILL CONTINUE A SLOW MOVEMENT TO THE SOUTH TONIGHT. COULD SEE SOME NOCTURNAL SHOWERS AND A FEW STORMS DEVELOP DURING THE LATE NIGHT AND BEFORE SUNRISE SOUTH OF THE BOUNDARY...MAINLY OVER LOWER ACADIANA...WHICH NAM AND RUC HINT AT. SO WILL KEEP CHANCE POPS GOING IN THAT AREA...AND TAPER THEM OFF TO SLIGHT CHANCE OR NONE...THE FURTHER WEST AND NORTH YOU GO. RUA PREV DISCUSSION... /ISSUED 711 PM CDT FRI AUG 10 2012/ UPDATE... A QUICK UPDATE TO REMOVE SOME OF OUR SE TX COUNTIES FM THE WATCH AND ADD A FEW FURTHER EAST IN LA. SCT STRONG TO SVR STORMS CONTINUE FROM NR BEAUMONT NE TOWARD ALEXANDRIA AND MARKSVILLE...WITH AN ESPECIALLY POTENT AND PROLIFIC LIGHTNING PRODUCING STORM JUST NE OF THE CWA DROPPING SWD TOWARD AVOYELLES PARISH. WILL CONTINUE TO MONITOR ACTIVITY...BUT ANTICIPATE MOST OF IT WILL BE DECREASING IN INTENSITY AND COVERAGE THE NEXT FEW HOURS. 24 PREV DISCUSSION... /ISSUED 617 PM CDT FRI AUG 10 2012/ DISCUSSION... 00Z TAF ISSUANCE. AVIATION... FRONTAL BOUNDARY OVER E TX/C LA IGNITING SCT/NUM TSRA JUST S OF THE BOUNDARY...WHICH WILL CONTINUE TO MOVE S THIS EVENING. INCREASED CHANCE OF TSRA EXPECTED FOR BPT/LCH BY 01-02Z...AND LFT/ARA BY 02-03Z THIS EVENING...WITH ACTIVITY LINGERING THRU 05-06Z. SVR WATCH 572 FOR SE TX/C AND SW LA THRU 05Z...NOT INCLUDING LFT/ARA. ACTIVITY EXPECTED TO DIMINISH BY 06Z...BUT NAM12 SHOWS REDEVELOPMENT TOWARDS 09-12Z ACROSS SC LA...WHICH WOULD AFFECT LFT/ARA DURING THIS TIME. WILL WAIT FOR 00Z RUN TO BITE ON THIS. DML PREV DISCUSSION... /ISSUED 501 PM CDT FRI AUG 10 2012/ SYNOPSIS... RUNNING A LITTLE LATE ON THE AFD THIS AFTN...BUT THAT TURNED OUT TO BE OK AS SEVERE THUNDERSTORM WATCH 572 WAS ISSUED AS I WAS PUTTING THIS TOGETHER EARLIER. ALREADY WENT AHEAD AND UPDATED ZONE AND COASTAL FORECASTS FOR THE WATCH. THE WATCH WAS PROMPTED BY A BAND OF STORMS THAT DEVELOPED QUICKLY THIS AFTN ALONG A PREFRONTAL TROF FM NATCHEZ TO JASPER TO CONROE. THESE STORMS RAPIDLY INTENSIFIED AS THEY ENTERED A VERY MOIST AND HEATED ATMOSPHERE ACRS SE TX AND WRN LA...AND ARE CAPABLE OF PRODUCING ABUNDANT CG LIGHTNING...GUSTY WINDS AND VERY HEAVY RAINFALL. OTHERWISE...THE LATEST UPPER AIR ANALYSES AND WV IMAGERY INDICATE THE AREA IS BETWEEN A TROF TO THE EAST AND A RIDGE OF HIGH PRESSURE ACRS THE SRN ROCKIES AND SW STATES. THIS IS PRODUCING A NLY FLOW ALOFT...WITH SEVERAL DISTURBANCES TRAVELING SOUTHWARD TOWARD THE REGION. ABUNDANT MOISTURE PERSISTS OVER THE AREA PER 12Z SOUNDINGS WITH PW VALUES AROUND 2 INCHES. AT THE SFC...A COLD FRONT WAS LOCATED FM GREENWOOD MS TO NR MONROE TO CENTERVILLE TX...SEPARATING DEWPOINTS IN THE MID 60S FM DEWPOINTS IN THE MID 70S. DISCUSSION... THINGS EXPECTED TO REMAIN ACTIVE FOR THROUGH EARLY EVENING AS STORMS CONTINUE TO FIRE ALONG THE AFOREMENTIONED TROF...WITH OUTFLOW BOUNDARY INTERACTIONS HELPING TO MAINTAIN ADDITIONAL DEVELOPMENT. ACTIVITY WILL TRAVEL SOUTHWARD...AND SHOULD DIMINISH BY MID-EVENING WITH THE LOSS OF DAYTIME HEATING...ALTHOUGH ANOTHER IMPULSE FURTHER UPSTREAM COULD BRING SOME MORE SCT ACTIVITY LATE TONIGHT. THE BIG QUESTION IS HOW FAR SOUTH WILL THE FRONT GET...AND VARIOUS MODEL GUIDANCE NOT IN TOTAL AGREEMENT ON HOW MANY OF US WILL SEE AT LEAST SOME RELIEF FM THE HUMIDITY. THE ECMWF AND NAM BOTH SHOW THE FRONT STALLING JUST NR OUR NRN CWA BORDER...WHILE THE CANADIAN...OPERATIONAL GFS AND GEM SHOW THE FRONT TREKKING FURTHER SOUTH INTO THE CWA...ESSENTIALLY STALLING IT CLOSER TO THE I-10 CORRIDOR. HPC GUIDANCE EARLIER TODAY LEANED TOWARD THE FORMER SOLUTIONS...BUT THE LATEST FCST SHOWS THE FRONT MOVING FURTHER SOUTH BEFORE STALLING. FOR THE GRIDS...CHOSE A BLEND OF GUIDANCE BUT WEIGHTED A LITTLE MORE ON THE NORTHERLY SOLUTIONS...WITH THE FRONT MAKING IT THROUGH AT LEAST THE NRN TIER OF COUNTIES/PARISHES. EXPECT SCT SHOWERS AND THUNDERSTORMS AGAIN SATURDAY...MAINLY ACRS SRN PORTIONS OF THE AREA WITH THE FRONT GRADUALLY WASHING OUT SATURDAY NIGHT INTO SUNDAY. RAIN CHANCES DIMINISH ON SUNDAY...WITH A RETURN TO A MORE TYPICAL SUMMERTIME PATTERN BY EARLY NEXT WEEK. HIGH PRESSURE WILL BECOME REESTABLISHED OVER THE NRN GULF AND GULF COAST STATES...WITH AFTN HIGHS IN THE 90S AND LOWS IN THE 70S. MARINE... HIGH PRESSURE RIDGING OVER THE NORTHERN GULF WILL MAINTAIN A LIGHT TO MODERATE SOUTHWESTERLY FLOW TONIGHT...WITH WINDS DIMINISHING OVER THE WEEKEND AS A WEAK FRONT STALLS ACROSS THE GULF COAST STATES. SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE MAINLY EAST OF SABINE PASS. A GENERALLY LIGHT ONSHORE FLOW...LOW SEAS AND MORE TYPICAL LATE NIGHT/EARLY MORNING SHOWERS WILL RESUME INTO THE COMING WEEK AS HIGH PRESSURE BECOMES REESTABLISHED OVER THE GULF COAST. 24 && .PRELIMINARY POINT TEMPS/POPS... KLCH 76 93 75 94 77 / 40 30 10 20 10 KBPT 76 93 74 94 77 / 40 20 10 20 10 KAEX 73 94 69 95 74 / 40 20 10 10 10 KLFT 76 92 74 95 76 / 40 30 10 20 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1120 PM MDT FRI AUG 10 2012 AVIATION SECTION UPDATED .DISCUSSION... UPDATE FORTHCOMING. HAVE LOWERED POPS ACROSS THE AREA TO BETTER REFLECT ONGOING CONDITIONS. RUC AND GFS MODELS CONTINUE TO INDICATE SCATTERED SHOWERS AND THUNDERSTORMS A POSSIBILITY ACROSS THE AREA AFTER MIDNIGHT. RADAR RETURNS INDICATE SCATTERED THUNDERSTORMS MOVING ACROSS SOUTHWEST MONTANA AT THIS TIME. EMANUEL && .AVIATION... UPDATED 0520Z. UPPER LEVEL TROF WITH ISOLATED SHOWERS AND THUNDERSTORMS WILL CONTINUE TO MOVE EASTWARD THRU SOUTHWEST AND CENTRAL MT OVER NEXT 2 TO 3 HRS. EXPECT CONDITIONS TO REMAIN VFR BUT KBZN/KLWT/KHVR MAY SEE BRIEF PERIOD OF MVFR VISIBILITY DUE TO MODERATE RAINFALL. SKIES WILL GRADUALLY CLEAR DURING THE OVERNIGHT PERIOD WITH JUST SCATTERED CLOUDS EXPECTED ACROSS MOST OF THE REGION ON SAT. FORECAST MODELS STILL INDICATING SOME INSTABILITY AND MOISTURE ASSOCIATED WITH A WEAK SECONDARY TROF SKIRTING THE US/CAN BORDER ON SAT AFTN SO HAVE ADDED MENTION OF VCSH AT KCTB/KHVR AFTER 20Z. WARANAUSKAS && .PREV DISCUSSION...ISSUED 245 PM MDT FRI AUG 10 2012 TONIGHT THROUGH SUNDAY...SCATTERED SHOWERS AND THUNDERSTORMS WILL CONTINUE OVER THE CENTRAL AND SOUTHERN SECTIONS OF THE REGION THROUGH THE EVENING HOURS...THUS POPS HAVE BEEN INCREASED IN THIS REGION. FURTHER NORTH...A PASSING THUNDERSTORM IS POSSIBLE. SOME STORMS OVER CENTRAL MONTANA COULD PRODUCE GUSTY WINDS THIS EVENING. EXPECT MOST OF THE THUNDERSTORM ACTIVITY TO TAPPER OFF BY EARLY SATURDAY MORNING...THEN A MOSTLY DRY AND QUIET WEEKEND IS EXPECTED FOR MUCH OF THE AREA. THE ONLY EXCEPTION IS A SMALL CHANCE FOR AN ISOLATED THUNDERSTORM ON SUNDAY AFTERNOON UP IN THE CUT BANK AREA...AS A WEAK UPPER LEVEL DISTURBANCE MOVES SOUTHWARD INTO THE REGION. SUMMER LIKE TEMPERATURES WILL CONTINUE OVER THE REGION...WITH MOST LOCATIONS RUNNING ABOUT 5 DEGREES ABOVE NORMAL FOR AFTERNOON HIGH TEMPERATURES ON SATURDAY AND SUNDAY. BRUSDA SUNDAY NIGHT THROUGH FRIDAY...THE UPPER LEVEL RIDGE OVER THE ZONES WILL BE FLATTENED SUNDAY NIGHT AS A SHORTWAVE MOVES THROUGH THE REGION. MID LEVEL MOISTURE WILL BE PRESENT AND SOME CONVECTION WILL CONTINUE THROUGH THE EVENING HOURS. THE SHORTWAVE WILL MOVE EAST OF THE ZONES AND HIGH PRESSURE WILL AGAIN DOMINATE ON MONDAY BUT THE NEXT LOW PRESSURE TROF WILL ALREADY BE MOVING OVER THE WEST COAST. THIS SHORTWAVE WILL MOVE ACROSS THE REGION TUESDAY AND THE ASSOCIATED COLD FRONT WILL BRING MUCH COOLER TEMPS INTO THE AREA. THE ECMWF IS CONSIDERABLY COOLER THAN THE GFS UNTIL MATCHING UP AGAIN 12Z SAT. THE ECMWF TENDS TO HANDLE SIGNIFICANT CHANGES IN TEMPERATURES BETTER THAN OTHER MODELS...SO HAVE TRENDED TEMPERATURES COOLER THAN MOST MODELS...BUT NOT AS COOL AS THE ECMWF FOR NOW. WILL CONTINUE TO MONITOR THE PROGRESS OF THIS SYSTEM. AN UPPER LEVEL HIGH PRESSURE RIDGE WILL BE OVER THE WEST COAST BY WEDNESDAY AND HEIGHTS OVER THE ZONES WILL BE REBUILDING. THIS HIGH PRESSURE RIDGE WILL CONTINUE TO BUILD THROUGH FRIDAY AND THE AIRMASS WILL REMAIN WARM AND DRY. TEMPS WILL BEGIN THE PERIOD WELL ABOVE NORMALS...DROP TO BELOW NORMALS TUESDAY AND WEDNESDAY...THEN BEGIN TO TREND UPWARDS AGAIN THROUGH FRIDAY. ZELZER/COULSTON && .PRELIMINARY POINT TEMPS/POPS... GTF 57 89 55 89 / 60 10 0 10 CTB 52 83 51 83 / 30 10 0 20 HLN 57 90 55 90 / 60 10 0 10 BZN 50 88 48 91 / 70 20 10 10 WEY 41 77 38 81 / 40 20 10 0 DLN 50 85 48 88 / 30 10 0 0 HVR 60 90 54 87 / 50 10 0 10 LWT 54 84 52 83 / 80 20 10 10 && .TFX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING BROADWATER... CASCADE...CENTRAL AND SOUTHERN LEWIS AND CLARK...CHOUTEAU... EASTERN TETON...FERGUS...JEFFERSON...JUDITH BASIN...NORTHERN ROCKY MOUNTAIN FRONT...SOUTHERN ROCKY MOUNTAIN FRONT...MEAGHER...BEAVERHEAD AND MADISON. RED FLAG WARNING UNTIL MIDNIGHT MDT THIS EVENING GALLATIN... && $$ WEATHER.GOV/GREATFALLS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1246 AM EDT SAT AUG 11 2012 .SYNOPSIS... AN APPROACHING COLD FRONT WILL BRING A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH THE WEEKEND. THE FRONT WILL STALL ACROSS THE AREA SUNDAY...AND DISSIPATE MONDAY. DRIER CONDITIONS WILL OVERSPREAD THE REGION DURING THE MID TO LATE WEEK PERIOD OF THE COMING WEEK. && .NEAR TERM /THROUGH SATURDAY/... AS OF 1230 AM SATURDAY...SEVERAL WAVES OF CONVECTION HAVE PUSHED ACROSS SE NORTH CAROLINA SINCE SUNSET...AND ANOTHER WAVE APPEARS TO BE COMING UP THE COAST AROUND GEORGETOWN CURRENTLY. WE HAVE INCREASED POPS INTO THE 60-70 PERCENT RANGE WITH THIS NEXT FEATURE...EXPECTING IT TO REACH MYRTLE BEACH AND WILMINGTON BEFORE SUNRISE. ALTHOUGH NOT INITIALIZED PERFECTLY THE 00Z AND 01Z RUNS OF THE HRRR SHOW AN EXPANSION OF INLAND CONVECTION OCCURRING IN THE 08-10Z TIME FRAME...PROBABLY LINKED TO THE APPROACH OF ANOTHER UPPER DISTURBANCE WITHIN THE BROADLY DIVERGENT PATTERN AT 200 AND 300 MB. WE`RE PROBABLY WITHIN A FEW DEGREES OF LOW TEMPERATURES AT MOST LOCATIONS...OTHERWISE FEW SIGNIFICANT CHANGES ARE PLANNED. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...PRIMARY WEATHER FEATURE IMPACTING THE WEEKEND IS A WEAK COLD FRONTAL PASSAGE ASSOCIATED WITH A TRAVERSING UPPER AND DE- AMPLIFYING TROUGH EARLY SUNDAY. THE NET RESULT IS LOTS OF DRY AIR ABOVE 9000 FEET BY SUNDAY AFTERNOON. AHEAD OF THIS SYSTEM WE HAVE A GOOD SHOT OF PCPN SATURDAY...TAPERING TO ISOLATED THROUGH SUNDAY. AT THE SURFACE THE FRONT IS SO WEAK THAT IT APPEARS SOUTHERLY LOW-LEVEL FLOW IS SUSTAINED THROUGH SUNDAY...WITH BRIEF VEERING TO WSW SUNDAY AFTERNOON AND NIGHT...ACCOMPANIED BY SEVERAL DEGREE DEW POINT DROPS LATE SUNDAY. THIS SHOULD TAKE AN EDGE OFF THE MUGGINESS LATE IN THE WEEKEND. BECAUSE THE SURFACE FRONT IS WEAK...LITTLE COOLING IS ANTICIPATED AND TEMPERATURES WILL ADHERE CLOSE TO CLIMATOLOGY SUNDAY...BUT A BIT COOLER THAN NORMAL SATURDAY DUE TO CLOUDS OR RAIN-COOLED AIR. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 3 PM FRIDAY...MODEL AGREEMENT IS FAIRLY GOOD ON MONDAY SHOWING A FAIRLY DRY WSW MID LEVEL FLOW AHEAD OF A TROUGH DEVELOPING OVER WESTERN GREAT LAKES. AT THE SURFACE THE GRADIENT IT QUITE WEAK AND LOW LEVEL FLOW OUT OF THE SW WILL KEEP DEEPEST MOISTURE OFFSHORE. THIS TROUGH SWINGS INTO THE EASTERN U.S. ON TUESDAY BUT THE FIRST HINTS AT MODEL SOLUTION DIVERGENCE STARTS TO APPEAR. LOWERED HEIGHTS ARGUABLY COULD SUPPORT SOME FORCING FOR RAINFALL BUT LOW LEVEL MOISTURE REMAINS QUESTIONABLE...AND THE WETTER LOOKING GFS SEEMS TO ADVECT IT IN FROM THE WEST...WHICH LOOKS OVERDONE. FROM THERE THE GFS AND CMC HOLD ON TO SOME EASTERN TROUGHINESS ALBEIT FURTHER TO THE EAST. THE OLD RUN OF THE EC IS MUCH MORE PROGRESSIVE AND QUICKLY FLATTENS OUT THE FLOW BEYOND WEDNESDAY. EITHER WAY THE FORECAST IMPLICATIONS LOCALLY ARE QUITE SIMILAR IN THAT RAIN CHANCES WILL BE QUITE LOW AND TEMPS NEAR CLIMO. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 06Z...MOD CONFIDENCE RW W/TEMPO MVFR CONDS WILL OCCUR AT THE COAST THRU 08-10Z AND AT FLO/LBT 08-12Z. ISOLD TS PSBL MAINLY AT THE COAST. CONFIDENCE LOW ON TIMING THUS HAVE USED PROB30 GROUPS FOR THUNDERSTORMS/IFR AFT 15Z. TIMING BASED ON BEST GFS VERTICAL VELOCITIES. EXTENDED OUTLOOK...CHANCE OF MORNING MVFR VSBYS IN BR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH SUNDAY. VFR MONDAY THROUGH WED. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1230 AM SATURDAY...A NEARLY STATIONARY FRONT ACROSS THE WESTERN CAROLINAS IS SQUEEZING THE WESTERN PERIPHERY OF THE BERMUDA HIGH AND CREATING A LOW LEVEL SOUTHWESTERLY JET ALONG OVER THE COASTAL CAROLINAS. SURFACE WIND SPEEDS HAVE BEEN MEASURED AS HIGH AS 23-27 KNOTS OUTSIDE OF CONVECTION IN THE PAST FEW HOURS...AND THESE STRONG WINDS SHOULD CONTINUE UP THROUGH DAYBREAK. SEVERAL WAVES OF SHOWERS AND STORMS HAVE AFFECTED THE CAPE FEAR REGION SINCE SUNSET...AND ANOTHER WAVE OF SHOWERS ARE APPROACHING GEORGETOWN AND WILL PROBABLY MOVE NORTHEAST ALONG THE COAST AFFECTING MYRTLE BEACH AND PERHAPS CAPE FEAR LATE TONIGHT. WINDS AND SEAS SUPPORT FORECASTS AND NO SIGNIFICANT CHANGES ARE PLANNED. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...S-SW WINDS WILL PREVAIL THROUGH THE WEEKEND AND FAR FROM IDEAL CONDITIONS EARLY IN THE GOING SINCE WE WILL BE COMING OFF ADVISORY CONDITIONS SATURDAY MID-MORNING. AS A WEAK LOW PRESSURE TROUGH APPROACHES LATE SATURDAY AND SUNDAY...WINDS WILL EASE SATURDAY NIGHT AND SUNDAY. THUS IT APPEARS MARINE CONDITIONS WILL IMPROVE THROUGH THE WEEKEND AFTER A ROUGH START EARLY SAT. ACTIVE AND STRONG TSTMS ARE POSSIBLE THROUGH SATURDAY NIGHT AND SOME MAY PRODUCE STRONG WIND GUSTS SINCE STORM MOTION WILL BE SWIFT...SSW TO NNE AT 25-35 KNOTS. THUS MARINERS ARE ENCOURAGED TO CONSULT RADAR TRENDS BEFORE HEADING OUT. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 3 PM FRIDAY...INITIALLY LIGHT SW FLOW ON MONDAY CAUSED BY WEST ATLANTIC HIGH PRESSURE. THE GRADIENT WILL TIGHTEN ON TUESDAY AS A SURFACE TROUGH DROPS INTO THE SOUTHEASTERN U.S. SEAS WILL THUS TRANSITION TO A GENTLE WIND WAVE/SWELL MIXTURE ON MONDAY TO BECOMING PREDOMINANTLY A SHORTER PERIOD WIND WAVE. SIMILARLY THE DOMINANT WAVE HEIGHT WILL BUILD. THE BOUNDARY WILL APPROACH AND WEAKEN BY WEDNESDAY VEERING AND DECREASING THE WINDS. SEAS WILL FOLLOW SUIT WHILE RETAINING THE WIND WAVE-RELATED SHORTER PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EDT SATURDAY FOR AMZ250-252. && $$ SYNOPSIS...DCH/TRA NEAR TERM...TRA SHORT TERM...MJC LONG TERM...MBB AVIATION...MRR/TRA
AREA FORECAST DISCUSSION...CORRECTED FIRE WX SECTION
NWS NORMAN OK
422 AM CDT SAT AUG 11 2012 .DISCUSSION... THE FIRST CONCERN IS ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS ESPECIALLY TODAY OVER NORTHWEST OKLAHOMA...THEN HOT WEATHER AND RAIN CHANCES ARE THE NEXT CONCERNS. THIS MORNING...A FEW HIGH BASED SHOWERS AND THUNDERSTORMS WILL AFFECT FAR WESTERN OKLAHOMA AND BRING LIGHT AMOUNTS OF RAINFALL. BASED ON THE LATEST HRRR OUTPUT...THIS ACTIVITY WILL DIMINISH AFTER 9 AM. KEPT 20 PERCENT CHANCE WEST OF AN ALVA TO ALTUS LINE TO ACCOUNT FOR THIS. OTHERWISE...DRY AND COOLER CONDITIONS WILL PREVAIL. A FEW LOCATIONS NEAR EL RENO AND ADA HAVE DROPPED TO THE UPPER 50S EARLY THIS MORNING. THIS AFTERNOON WILL BE PARTLY TO MOSTLY SUNNY AND ABOUT 2 TO 5 DEGREES WARMER THAN YESTERDAY. PREFERRED THE HOTTER 00Z METMOS HIGHS. SOUTHERLY WINDS WILL INCREASE OVER WESTERN OKLAHOMA. TONIGHT...INCREASING CLOUDS AND WINDS WILL ALLOW FOR WARMER CONDITIONS. KEPT 20 PERCENT CHANCE MAINLY OVER NORTHERN OKLAHOMA AS A FEW HIGH BASED SHOWERS AND STORMS MAY DEVELOP...THOUGH CONFIDENCE IS NOT THE GREATEST. ANY RAINFALL WILL BE LIGHT. SUNDAY...VERY HOT TEMPERATURES AND A FEW AFTERNOON AND EVENING SEVERE THUNDERSTORMS REMAIN THE BIG CONCERNS. TRIPLE DIGIT HEAT IS EXPECTED ACROSS MOST...IF NOT ALL...OF THE AREA WITH HIGHS POSSIBLY APPROACHING 110 DEGREES OVER SOUTHWEST OKLAHOMA AND WESTERN NORTH TEXAS. WENT NEAR OR SLIGHTLY ABOVE 00Z METMOS HIGHS. HEAT INDICES MAY APPROACH 105 DEGREES SOUTH OF AN ALTUS TO STILLWATER LINE...SO A HEAT ADVISORY MAY BE NECESSARY. AS FOR SEVERE THUNDERSTORM POTENTIAL SUNDAY AFTERNOON AND EVENING...LATEST NAM12 RUNS SUGGESTED A FEW HIGH BASED THUNDERSTORMS WILL DEVELOP NEAR A FRONT...SOMEWHERE NEAR A VERNON TO OKLAHOMA CITY LINE 1 TO 4 PM CDT...THEN MOVE SOUTHEAST. DUE TO MODERATE SHEAR AND INSTABILITY...A FEW DAMAGING WIND GUSTS OVER 60 MPH WOULD BE THE MAIN HAZARD. BELIEVE ANY SEVERE THREAT WOULD DIMINISH BY MIDNIGHT. MONDAY THROUGH WEDNESDAY...MAINLY HOT AND DRY CONDITIONS ARE EXPECTED...THOUGH CONFIDENCE IS DECREASING TUESDAY AND WEDNESDAY AS CLOUDS AND INCREASING MID LEVEL MOISTURE MAY ALLOW FOR SOME STORMS AND COOLER TEMPERATURES. FOR NOW...DID NOT MAKE MANY CHANGES DURING THIS TIME FRAME. THURSDAY AND FRIDAY...A SIGNIFICANT COOLDOWN WITH INCREASING RAIN CHANCES MAY OCCUR WITH THE PASSAGE OF A COLD FRONT AS LATEST MODELS WERE IN DECENT AGREEMENT. MBS && .FIRE WEATHER... UPGRADED THE FIRE WEATHER WATCH TO A RED FLAG WARNING ACROSS WEST CENTRAL AND NORTHWEST OKLAHOMA DUE TO MODERATE CONFIDENCE THAT CRITICAL FIRE WEATHER CONDITIONS WILL BE MET. WINDS WILL BE MARGINAL. ANY RAINFALL IN THE WARNED AREA THIS MORNING WILL BE ISOLATED AND VERY LIGHT...WHICH IS NOT EXPECTED TO HAVE ANY SUBSTANTIAL EFFECT ON THE IGNITION OF WILDFIRES. ELEVATED TO NEAR CRITICAL FIRE WEATHER CONDITIONS WILL CONTINUE THROUGH AT LEAST MIDWEEK. THERE IS A LOW CHANCE FOR NEAR CRITICAL FIRE WEATHER CONDITIONS NEAR A WICHITA FALLS TO OKLAHOMA CITY TO STILLWATER LINE SUNDAY AFTERNOON. DUE TO MARGINAL WINDS MAINLY UNDER 20 MPH AND HUMIDITY LEVELS ABOVE 20 PERCENT... DID NOT ISSUE A FIRE WEATHER WATCH. WEDNESDAY MAY HAVE A HIGHER CHANCE FOR CRITICAL FIRE WEATHER CONDITIONS ACROSS THE AREA. MBS && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 97 75 103 73 / 0 10 20 20 HOBART OK 99 74 103 72 / 20 10 10 10 WICHITA FALLS TX 101 76 108 76 / 0 10 20 20 GAGE OK 97 71 102 67 / 20 20 10 0 PONCA CITY OK 97 75 102 68 / 0 20 20 20 DURANT OK 96 73 102 74 / 0 10 20 30 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 10 PM CDT THIS EVENING FOR OKZ004-005-009-010-014>016-021-022. TX...NONE. && $$ 25/17
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
157 AM EDT SAT AUG 11 2012 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE WEST THIS AFTERNOON AND SHOULD GET HUNG UP ACROSS THE MOUNTAINS TONIGHT. THE FRONT IS EXPECTED TO PUSH THROUGH LATE SATURDAY AND THEN SOUTH OF THE AREA ON SUNDAY. HIGH PRESSURE WILL MOVE IN FOR THE EARLY PART OF NEXT WEEK. MEANWHILE ANOTHER FRONT WILL APPROACH THE AREA BY MID WEEK. && .NEAR TERM /THROUGH TODAY/... 130 AM UPDATE...NO MAJOR CHANGES NEEDED FOR THE FCST. ADJUSTED TEMPS DOWN A FEW DEGREES WITH THE RAIN COOLED STORM AREAS...GENERALLY THE NRN UPSTATE. POPS AND SKY LOOK GOOD. AS OF 1030 PM...CONVECTIVE COVERAGE IS BEGINNING TO INCREASE OVER NE GA AND THE WRN UPSTATE...CONSISTENT WITH THE HRRR OUTPUT. OVERALL IT APPEARS THAT SHRA/TSTMS WILL CONTINUE FOR SEVERAL MORE HOURS OVER THE REGION...THOUGH THE CHANCES OF SEVERE WEATHER OR FLASH FLOODING APPEAR TO BE DECREASING WITH THE LOSS OF HEATING. AS OF 530 PM...A STRONG STORM HAS MOVED INTO RABUN COUNTY...AND A LINE OF CONVECTION IS ORGANIZING OVER THE GREAT VALLEY OF TN. HOWEVER...NOT MUCH IS HAPPENING OVER THE ERN FOOTHILLS AND PIEDMONT ZONES ATTM AND I/VE CUT BACK POPS IN THOSE LOCATIONS FOR THE NEXT COUPLE HOURS. THERE CONTINUES TO BE GOOD MODEL AGREEMENT THAT CONVECTION WILL BECOME MORE WIDESPREAD THROUGH BOTH AN MCS MOVING INTO THE NC MTNS AND CONVECTION DEVELOPING IN STRENGTHENING LLVL CONVERGENCE ACROSS THE FOOTHILLS LATER THIS EVENING. AND THIS IS REFLECTED WELL IN THE GRIDS. AS OF MID AFTERNOON...VISIBLE SATELLITE IMAGERY SHOWS LOW CONVECTIVE CLOUDS SCATTERING SUFFICIENTLY E OF THE BLUE RIDGE TO ALLOW HEATING THAT HAS RAISED SFC-BASED CAPE INTO THE 1500-2000 J/KG RANGE ON THE LAPS ANALYSIS. SHOWER ACTIVITY HAS DEVELOPED OVER THE CLT METRO AREA AND ALONG THE BLUE RIDGE...WITH MORE ACTIVITY CLOSER TO THE FRONT OVER THE CUMBERLAND PLATEAU. EXPECT SHOWERS AND STORMS TO CONTINUE DEVELOPING AND BECOMING MORE NUMEROUS...MAINLY OVER THE MTNS AND FOOTHILLS...THROUGH THE LATE AFTERNOON. SEVERE WEATHER REMAINS A CONCERN WITH SOME DRY AIR ABOVE 500 MB...ALTHO IN GENERAL THE SOUNDINGS DO NOT LOOK AS FAVORABLE AS YESTERDAY. OVER THE NEXT 24 HOURS OR SO...THE MODELS ARE IN GOOD AGREEMENT WITH THE EVOLUTION OF WEATHER FEATURES...AND IN PARTICULAR SHOW THE AXIS OF THE UPPER TROF AND THE UPPER JET REMAINING TO OUR WEST. THIS WILL ACT TO KEEP THE SURFACE FRONT HUNG UP PROBABLY OVER THE MTNS THROUGH SATURDAY AFTERNOON. THE TREND...THEREFORE...IS TO HOLD ON TO MORE OF A CHANCE OF SHOWER/TSTM ACTIVITY OVER A LARGER PART OF THE FCST AREA THROUGH 00Z SUNDAY. THE THREAT OF SEVERE STORMS WILL SLOWLY INCREASE AS BUOYANCY AND DCAPE SLOWLY BECOME MORE FAVORABLE...WITH JUST ENOUGH SHEAR TO PERHAPS ORGANIZE STORMS EARLY THIS EVENING. THE 4KM WRF DEVELOPS A LINE OF STORMS OFF THE BLUE RIDGE AROUND 23Z WHILE THE HRRR BRINGS THE LINE OF STORMS ACROSS TN AND INTO THE NC MTNS AROUND THAT TIME. ABUNDANT LOW LEVEL MOISTURE AND ENUF UPPER FORCING WILL EXIST TO WARRANT A LIKELY POP INTO THE EVENING HOURS. WILL KEEP POP IN THE CHANCE RANGE OVERNIGHT AS ADDITIONAL STORMS COULD REDEVELOP AT ANY TIME WITH THE SITUATION REMAINING UNCHANGED. TEMPS WILL REMAIN MILD. ON SATURDAY...EXPECT THE FRONT TO BE HUNG UP OVER THE MTNS AT SUNRISE. UNLESS EXTENSIVE CONVECTIVE DEBRIS PREVENTS IT...CONVECTION SHOULD RE-FIRE EARLY IN THE DAY CLOSE TO THE FRONT AS IT DID TO OUR WEST THIS PAST MORNING. UPPER DIVERGENCE...DPVA...AND PLENTY OF MOISTURE SUGGEST ANOTHER POP IN THE LIKELY RANGE BY AFTERNOON OVER THE PIEDMONT...AND A CHANCE UP TO THE BLUE RIDGE. A GUIDANCE BLEND WAS USED FOR HIGH TEMPS. && .SHORT TERM /TONIGHT THROUGH MONDAY/... AT 200 PM EDT FRIDAY...12Z GFS AND NAM STILL SOMEWHAT AT ODDS AS TO HOW FAST THE FRONTAL BAND OF DEEP LAYER MOISTURE AND PRECIP WILL EXIT THE FORECAST AREA OVER THE EAST. THE NAM STIL IS FASTER AND HAS THE DEEP LAYER FRONTAL MOISTURE EAST OF THE AREA BY 00Z SUN...WHILE THE GFS IS CONSIDERABLY SLOWER AND WETTER. THE SREF APPEARS TO CONTINUE TO BE A GOOD COMPROMISE FOR THE SOLUTION. THE SREF KEEPS PRECIP CHANCES OVER THE EASTERN MOST PART OF THE FORECAST AREA EARLY ON SAT NIGHT...AND THEN MOVES THE MOISTURE/PRECIP EAST BY MIDNIGHT. WILL ALSO SCATTER AND CLEAR THE CLOUDS FROM NW TO SE SAT NIGHT. HIGH PRESSURE BUILDS OVER THE AREA ON SUN WHICH SHOULD PRODUCE A VERY NICE DAY WITH DEWPOINTS MIXING OUT INTO THE 50S OVER THE MOUNTAINS AND LOW 60S ELSEWHERE. THE HIGH SHIFTS EAST OF THE AREA ON MONDAY...BUT ITS LINGERING INFLUENCE SHOULD ALLOW FOR ANOTHER DRY DAY ON MONDAY. TEMPS ARE EXPECTED TO BE SLIGHTLY BELOW CLIMO ON SUN AND NEAR CLIMO ON MON. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AT 130 PM EDT FRIDAY...A SOMEWHAT PROGRESSIVE PATTERN APPEARS TO BE IN STORE DURING THE MEDIUM RANGE. THE UPPER AIR PATTERN WILL GENERALLY FEATURE A MEAN TROUGH OVER THE EASTERN U.S. WITH INDICATIONS FROM THE LATEST 12Z GFS OF BUILDING HEIGHTS TOWARD THE END OF NEXT WEEK OVER THE EAST. LATEST HPC/GFS GUIDANCE SUGGESTS A WEAK COLD FRONT WILL CROSS THE REGION ON TUE ALONG WITH SCATTERED CONVECTION. THE GFS DRIVES THE FRONT SE OF THE AREA BY WED WITH HIGH PRESSURE BUILDING IN THROUGH THU. THUS ONLY CLIMO TYPE POPS FOR AFTERNOON CONVECTION IN THE MOUNTAINS WED AND THU. ANOTHER FRONT APPROACHES THE AREA ON FRI AND PER HPC WILL FORECAST CHANCE TYPE POPS. TEMPS SHOULD BE NEAR CLIMO THROUGH THE PERIOD. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AT KCLT...KEEPING AN EYE ON THE CONVECTION UPSTREAM OF THE TERMINAL. COULD NEED AN AWW FOR CTG LTG...BUT NOT EXPECTING SIGFNT WIND SHIFTS OR CIG/VSBY ISSUES WITH THAT STORM. THE OVERALL PREFRONTAL ZONE IS FAIRLY WEAK...BUT IT WILL SHIFT EAST THROUGH THE MORNING...LIKELY CREATING A LOWERING OF CIGS TO IFR BY DAYBREAK. BRING MVFR BY 14Z...SIMILAR TO YDAY/S MORNING AIRMASS TRANSITION. THUNDER CLOSE BY AGAIN THIS AFTERNOON...MOVING EAST OF THE TERMINAL BY 00Z PER THE WRF ARW. ELSEWHERE...SHOWERS AND THUNDER TO AFFECT THE SC TERMINALS OVER THE NEXT FEW HRS. HAVE CIGS LOWERING AT ALL SITES TO MVFR/IFR AFT 09Z...SOME OF WHICH HAVE ALREADY FALLEN DUE TO RECENT PRECIP. A LITTLE MORE DRYING AT KAVL AND KHKY COULD ALLOW FOR IFR VSBY BY DAYBREAK. SHOWERS AND THUNDER WILL BE ISOL THIS AFTERNOON AND THE MAIN LINE SHOULD BE EAST OF ALL SITES...HOWEVER CANNOT RULE OUT UPPER TROF INDUCING CONVECTION IN BETTER INSOLATION AREA POST FROPA...SO KEPT PROB30 TS AT ALL SITES EXCEPT KAVL. OUTLOOK...A COLD FRONT WILL SLOWLY CROSS THE AREA LATE SATURDAY... WITH DRIER HIGH PRES BUILDING IN FROM THE W THE LATTER HALF OF THE WEEKEND. WEAK HIGH PRESSURE WILL LINGER THROUGH EARLY NEXT WEEK. AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)... WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PM NEAR TERM...MCAVOY/SBK SHORT TERM...LG LONG TERM...LG AVIATION...SBK
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
313 AM CDT SAT AUG 11 2012 .SHORT TERM...TONIGHT THROUGH MONDAY NIGHT 313 AM CDT SAT AUG 11 2012 MAIN FORECAST CHALLENGE IS ON RAIN CHANCES SUNDAY THROUGH MONDAY. 07Z SURFACE ANALYSIS SHOWS HIGH PRESSURE CENTERED FROM SOUTHERN ONTARIO...SOUTHWARD INTO SOUTHERN MINNESOTA. AIRMASS WAS RELATIVELY DRY...WITH MANY OF THE VALLEY LOCATIONS STILL SEEING 7 TO 8 DEGREE TEMPERATURE DEWPOINT SPREADS. GRADIENT HAS ALSO BEEN STRONG ENOUGH TO KEEP LOW LEVELS MIXED AND THUS NO FOG IS BEING REPORTED. ANOTHER NICE DAY IS IN STORE FOR THE AREA TODAY. HIGH PRESSURE WILL REMAIN OVERHEAD RESULTING IN ANOTHER DAY WITH LOTS OF SUNSHINE AND TEMPERATURES SIMILAR TO YESTERDAYS. A SHORTWAVE WILL DROP ACROSS THE PLAINS LATER TODAY AND BECOME THE MAIN WEATHER INFLUENCE FOR TONIGHT THROUGH MONDAY. CLOUDS WILL INCREASE TONIGHT WITH SHOWERS APPROACHING THE WESTERN SECTIONS OF THE AREA BY 12Z SUNDAY. WAVE THEN TRANSLATES ACROSS IOWA...WITH THE STRONGEST FORCING REMAINING ACROSS THE SOUTHWEST HALF OF THE FORECAST AREA...ESPECIALLY NORTHEAST IOWA AND SOUTHWEST WISCONSIN. MOISTURE TRANSPORT FOCUSES INTO THIS AREAS AS WELL...ESPECIALLY SUNDAY NIGHT WITH PRECIPITABLE WATER VALUES INCREASING TO NEAR 1 INCH. WITH THE ATTENDANT SURFACE LOW TRACKING ACROSS SOUTHERN IOWA SUNDAY NIGHT...COULD BE SOME SUBSTANTIAL RAINS IN THE DEFORMATION AREA THAT WILL BE LOCATED OVER NORTHEAST IOWA AND SOUTHWEST WISCONSIN. GFS INDICATING RATHER STRONG BAND OF FRONTOGENETIC FORCING NORTH OF THE LOW. DID RAISE BOTH PROBABILITIES AND QPF AMOUNTS FROM SUNDAY THROUGH MONDAY. LESSER PROBABILITIES FURTHER NORTH...WHERE FORCING IS WEAKEST AND LOW LAYERS APPEAR TO REMAIN RATHER DRY. INSTABILITIES VERY LIMITED SO EXPECT ONLY ISOLATED THUNDERSTORMS AT BEST. SHORTWAVE DOES PUSH EAST ON MONDAY AS HIGH PRESSURE BUILDS INTO THE REGION. PROBABILITIES WILL TAPER OFF MONDAY NIGHT AS SUBSIDENCE OVERTAKES THE AREA. TEMPERATURES COULD BE RATHER TRICKY SUNDAY AND MONDAY WITH THE CLOUDS AND SHOWERS. GUIDANCE NUMBERS SUGGEST HIGHS JUST IN THE LOWER 70S IN THE RAIN AREA...WITH MID 70S FURTHER NORTH AND EAST. .LONG TERM...TUESDAY THROUGH FRIDAY 313 AM CDT SAT AUG 11 2012 THE FLOW WILL BE RATHER PROGRESSIVE THROUGH THE PERIOD. INITIAL WAVE WILL PUSH EAST OF THE AREA ON TUESDAY...WITH HIGH PRESSURE SETTLING IN OVER THE AREA. THIS WILL BE SHORT LIVED AS THE NEXT SHORTWAVE BEGINS TO DIG ACROSS THE PLAINS AND THEN ROTATES ACROSS THE REGION WEDNESDAY THROUGH THURSDAY WITH THE ATTENDANT COLD FRONT PUSHING THROUGH WEDNESDAY NIGHT. SURFACE HIGH PRESSURE THEN BUILDS IN FOR FRIDAY. RAIN CHANCES LOOK BEST FOR WEDNESDAY NIGHT INTO THURSDAY. && .AVIATION...THROUGH 06Z SUNDAY 1153 PM CDT FRI AUG 10 2012 HIGH PRESSURE...CURRENTLY CENTERED OVER CENTRAL MINNESOTA...WILL BUILD SOUTHEAST INTO THE REGION OVERNIGHT. WHILE THE WINDS IN THE BOUNDARY LAYER WILL LIKELY DECOUPLE AND GO CALM AFTER MIDNIGHT...THE RAP CONTINUES TO SUGGEST THAT THE WINDS JUST ABOVE THE BOUNDARY LAYER WILL BE NORTHEAST AT 10 TO 15 KNOTS. IN ADDITION... THE SOUNDINGS DO NOT SHOW MUCH MOISTURE IN THE BOUNDARY LAYER AT ALL. THINKING THAT IF ANY FOG DOES DEVELOP IN THE MISSISSIPPI RIVER VALLEY...IT WILL BE SCATTERED AND VERY SHALLOW. AS A RESULT... KEPT A BCFG IN THE KLSE TAF...BUT WOULD NOT BE SURPRISED AT ALL THAT NO FOG DEVELOPS THERE. MEANWHILE FURTHER SOUTH...EXPECT TO SEE SOME VALLEY FOG DEVELOP IN THE WISCONSIN AND KICKAPOO RIVER VALLEY AFTER 11.06Z AND DISSIPATE AROUND 11.13Z. ADDITIONAL AREAS OF FOG WILL BE POSSIBLE ACROSS CENTRAL WISCONSIN ESPECIALLY NEAR KVOK AND KBCK. ON SATURDAY AFTERNOON AND EVENING...A LOW PRESSURE SYSTEM WILL APPROACH THE REGION. THIS SYSTEM WILL BRING AN INCREASE IN THE HIGH CLOUDS ACROSS THE REGION. && .ARX WATCHES/WARNINGS/ADVISORIES... 313 AM CDT SAT AUG 11 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...RABERDING LONG TERM...RABERDING AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1153 PM CDT FRI AUG 10 2012 .SHORT TERM...TONIGHT 929 PM CDT FRI AUG 10 2012 STILL HAVE NOT SEEN MUCH RECOVERY IN THE DEW POINTS THIS EVENING. IN MOST LOCATIONS...THE DEW POINTS HAVE ONLY CLIMBED 2 DEGREES. WITH THE EXCEPTION OF KVOK...KTOB..KOVS...AND KFKA...THE TEMPERATURE/DEW POINT SPREADS ARE GREATER THAN 10 DEGREES. WITH SURFACE RIDGE BUILDING SOUTHEAST ACROSS THE AREA...THE SURFACE WINDS HAVE DECREASED AS EXPECTED. HOWEVER THERE IS STILL A 10 TO 15 KNOT WIND AT THE OFFICE AND THE RAP CONTINUES TO SHOW THESE WINDS WILL REMAIN LIKE THIS ALL NIGHT. AS A RESULT... THINKING THAT THE FOG POSSIBILITY AT KLSE IS NOT THAT GREAT. THIS WILL LIKELY THE CASE IN THE ENTIRE UPPER MISSISSIPPI RIVER VALLEY. ONE CASE THAT LOOKS LIKELY TO SEE VALLEY FOG WILL BE IN THE WISCONSIN AND THE LOWER PORTION OF KICKAPOO RIVER VALLEY. ALSO WOULD NOT BE SURPRISED TO SEE SOME FOG NEAR VOLK FIELD. .LONG TERM...TUESDAY THROUGH FRIDAY 253 PM CDT FRI AUG 10 2012 10.12 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT TUESDAY THROUGH EARLY THURSDAY THEN DIVERGE GREATLY LATE THURSDAY THROUGH FRIDAY. A BRIEF WARM UP IS IN STORE FOR THE AREA TUESDAY INTO WEDNESDAY WITH HIGHS REBOUNDING INTO THE LOWER 80S. A STRONG COLD FRONT IS EXPECTED TO PUSH INTO THE AREA DURING THE DAY ON THURSDAY BRINGING SHOWERS AND THUNDERSTORMS TO THE AREA. STRONG SHEAR APPEARS TO BE LACKING WITH THE LATEST SET OF FORECAST MODEL RUNS DURING THE DAY ON THURSDAY WITH THE STRONGEST SHEAR WELL BEHIND THE COLD FRONT. DETAILS THIS FAR OUT ARE UNCLEAR WITH THE VARYING MODEL SOLUTIONS SO DIFFICULT TO DETERMINE SEVERE WEATHER POTENTIAL WITH THIS SYSTEM. MODELS ARE POINTING TOWARDS A COOL DOWN FOR LATE NEXT WEEK BEHIND THE FRONT AS A LONG WAVE TROUGH DEVELOPS ACROSS THE UPPER MIDWEST/GREAT LAKES. AT THIS TIME IT APPEARS THAT HIGHS WILL STRUGGLE TO GET OUT OF THE 60S ON FRIDAY. && .AVIATION...THROUGH 06Z SUNDAY 1153 PM CDT FRI AUG 10 2012 HIGH PRESSURE...CURRENTLY CENTERED OVER CENTRAL MINNESOTA...WILL BUILD SOUTHEAST INTO THE REGION OVERNIGHT. WHILE THE WINDS IN THE BOUNDARY LAYER WILL LIKELY DECOUPLE AND GO CALM AFTER MIDNIGHT...THE RAP CONTINUES TO SUGGEST THAT THE WINDS JUST ABOVE THE BOUNDARY LAYER WILL BE NORTHEAST AT 10 TO 15 KNOTS. IN ADDITION... THE SOUNDINGS DO NOT SHOW MUCH MOISTURE IN THE BOUNDARY LAYER AT ALL. THINKING THAT IF ANY FOG DOES DEVELOP IN THE MISSISSIPPI RIVER VALLEY...IT WILL BE SCATTERED AND VERY SHALLOW. AS A RESULT... KEPT A BCFG IN THE KLSE TAF...BUT WOULD NOT BE SURPRISED AT ALL THAT NO FOG DEVELOPS THERE. MEANWHILE FURTHER SOUTH...EXPECT TO SEE SOME VALLEY FOG DEVELOP IN THE WISCONSIN AND KICKAPOO RIVER VALLEY AFTER 11.06Z AND DISSIPATE AROUND 11.13Z. ADDITIONAL AREAS OF FOG WILL BE POSSIBLE ACROSS CENTRAL WISCONSIN ESPECIALLY NEAR KVOK AND KBCK. ON SATURDAY AFTERNOON AND EVENING...A LOW PRESSURE SYSTEM WILL APPROACH THE REGION. THIS SYSTEM WILL BRING AN INCREASE IN THE HIGH CLOUDS ACROSS THE REGION. && .ARX WATCHES/WARNINGS/ADVISORIES... 253 PM CDT FRI AUG 10 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...BOYNE LONG TERM...WETENKAMP AVIATION...BOYNE
AREA FORECAST DISCUSSION
NWS NEW YORK NY
822 AM EDT SAT AUG 11 2012 .SYNOPSIS... A SLOW MOVING COLD FRONT WILL MOVE TOWARDS THE REGION TODAY WITH A LOW DEVELOPING ALONG IT TONIGHT AS IT WEAKENS IN THE REGION. THE FRONT MOVES ACROSS THE WHOLE REGION BY SUNDAY EVENING. HIGH PRESSURE BUILDS INTO THE REGION FOR THE START OF THE NEW WEEK...THEN UNSETTLED WEATHER RETURNS LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... TEMPS AND DEWPOINTS ON TRACK. ADJUSTED POPS A FEW HOURS LATER COMPARING TO RECENT RADAR REFLECTIVITY TRENDS. NOTING HRRR FORECAST REFLECTIVITY FIELDS ARE AGGRESSIVE IN BRINGING IN AND DEVELOPING ACROSS THE AREA WITH MORE SHOWERS THIS MORNING. EQUIVALENT BAROTROPIC STRUCTURE TO LOW NEAR LAKE HURON. THIS LOW SLOWLY WEAKENS AND MOVES NORTH...FARTHER AWAY FROM ITS ASSOCIATED FRONTAL SYSTEM TO THE SOUTH AND EAST. THE TIMING REPRESENTS A SLOWER TIMING OF THE FRONTAL MOVEMENT. THE AREA STAYS IN THE WARM SECTOR THROUGH THE DAY WITH EASTERN SECTIONS CLOSER TO LOW LEVEL JET DEVELOPMENT ASSOCIATED WITH SECONDARY CYCLOGENESIS NEAR DELMARVA. A COLD FRONT AT THE SURFACE SLOWLY APPROACHES FROM THE WEST AND MOVES INTO THE AREA...WEAKENING AS IT DOES SO. THERE WILL BE EMBEDDED SHORTWAVES MOVING THROUGH ALOFT ON A SSW SYNOPTIC FLOW WITH THE LOCAL REGION NEAR THE SOUTHERN END OF A REGION OF DECENT MID LEVEL Q VECTOR CONVERGENCE. PW VALUES REMAIN IN GENERAL 1.8 TO 2 INCH RANGE FOR CITY AND EASTERN SECTIONS WITH DEEP TROPICAL SYNOPTIC FLOW. NORTH AND WEST OF THE CITY...THERE ARE SIGNS SOME DRIER AIR WILL TRY TO WORK INTO THE ATMOSPHERE...ALLOWING FOR PW VALUES TO DROP A FEW TENTHS OF AN INCH BY THE END OF THE AFTERNOON INTO THE EVENING. 2/3 MET AND 1/3 MAV FOR MAX TEMPS TODAY. GREATER WEIGHT WITH COOLER GUIDANCE WITH ABUNDANT CLOUDS AND HIGHER POPS EXPECTED. ANY SHOWERS AND THUNDERSTORM COULD PRODUCE HEAVY DOWNPOURS AS WELL AS GUSTY WINDS WITH BULK SHEAR 0-6KM OF AROUND 30 KT. TRAINING OF CELLS IS PROBABLE WITH PARALLEL FLOW FROM TO LOW TO UPPER LEVELS. THERE IS A HIGH RISK FOR RIP CURRENTS AT ATLANTIC OCEAN BEACHES THIS AFTERNOON AND EVENING. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY NIGHT/... COLD FRONT WILL BE MOVING THROUGH BY LATE SUNDAY AFTERNOON AT LEAST ACROSS THE WESTERN HALF OF THE CWA. AGAIN...A SLOWER TIMING OF THE FRONT HAS BEEN CONVEYED BY MUCH OF THE NUMERICAL GUIDANCE. POPS INCREASED FROM PREVIOUS FORECAST WITH SOME LINGERING SHOWERS AND THUNDERSTORMS TONIGHT. THE COVERAGE WILL BE HIGHEST OUT EAST...WHERE BETTER DYNAMICS WILL BE. AGAIN WITH PW VALUES HIGH AND BULK SHEAR O-6 KM NEAR 30-35 KT...THUNDERSTORMS WILL BE CAPABLE OF PRODUCING GUSTY WINDS AND TORRENTIAL RAIN. THE JET STREAK COMES THROUGH TONIGHT AS WELL AND THE REGION WILL BE IN THE RIGHT REAR QUAD WHICH COULD LEAD TO FURTHER WESTWARD EXPANSION OF THE HIGHER COVERAGE OF SHOWERS AND THUNDERSTORMS TONIGHT. CURRENT THINKING STILL HAS THIS HIGHER COVERAGE MOSTLY OVER EASTERN LONG ISLAND AND SOUTHEAST CONNECTICUT WHERE MORE INSTABILITY WILL BE. BLEND OF MET...MAV...AND NAM12 SFC TEMPS FOR MIN TEMPS TONIGHT WITHOUT MUCH DIURNAL TEMP RANGE EXPECTED. SOUTHERLY FLOW WILL BE STILL IN PLACE. A WAVE OF LOW PRESSURE DEVELOPS ALONG THE COLD FRONT WHICH WILL BE MOVING INTO THE REGION. 2/3 MAV AND 1/3 MET FOR MAX TEMPS ON SUN. AGAIN...THIS IS FAVORING THE COOLER GUIDANCE. IT DOES APPEAR THIS WILL BE A WARMER DAY FOR WESTERN SECTIONS AS DRIER AIR MOVES FARTHER EAST IN THE AFTERNOON HOURS BEHIND THE COLD FRONT. POPS FOR SHOWERS DIMINISH AS WELL FROM WEST TO EAST. THUNDERSTORMS WILL BE MORE ISOLATED GIVEN THE LOWER CAPE ACROSS THE REGION OF LESS THAN 1000 J/KG FOR MOST LOCATIONS. FOR MONDAY....COLD FRONT EAST OF REGION AND MORE STABLE AIR IN PLACE AS HIGH PRESSURE BUILDS IN. WARMER TEMPS EXPECTED WITH WARMER MET GUIDANCE CHOSEN. FLOW AT SFC TURNS MORE WESTERLY WITH DRIER AIR WORKING ITS WAY IN...HELPING INCREASE DIURNAL WARMTH. MAV/MET BLEND USED FOR MIN TEMPS MONDAY NIGHT WITH NEAR NORMAL TEMPS EXPECTED AS HIGH PRESSURE MOVES OFFSHORE. && .LONG TERM /TUESDAY THROUGH FRIDAY/... WITH THE HIGH MOVING OFFSHORE MONDAY NIGHT AND LOW PRES TRACKING THROUGH THE GREAT LAKES AND OHIO VALLEY...A WARM FRONT WILL LIFT NORTH INTO THE REGION MONDAY NIGHT/TUESDAY MORNING. SOME SHOWERS/THUNDERSTORMS EXPECTED WITH ITS PASSAGE. AS THE LOW TRACKS INTO EASTERN CANADA...A SECONDARY LOW WILL FORM OVER THE DELMARVA AREA ON TUESDAY...AND THIS SYSTEM WILL KEEP SHOWERS AND THUNDERSTORMS IN THE FORECAST THROUGH WEDNESDAY. WEAK HIGH PRES WILL MOVE THROUGH THE REGION THURSDAY...THEN ANOTHER SYSTEM WILL IMPACT THE AREA LATE IN THE WEEK. THERE ARE INCONSISTENCIES AMONG THE MODELS...RESULTING IN A LOW CONFIDENCE FORECAST FOR THE LONG TERM PERIOD. HPC GUIDANCE WAS CLOSELY FOLLOWED AS A RESULT. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... A COLD FRONT SLOWLY APPROACHES FROM THE WEST THROUGH SUNDAY. LOW CONFIDENCE FORECAST ON TIMING OF CONVECTION AND STRATUS/FOG TONIGHT. MVFR TO IFR CONDS EARLY WILL LIFT TO VFR BY AROUND 14Z. EXCEPTION IS KGON WHO MAY HOLD ON TO MVFR CIGS FOR MOST OF THE DAY. DUE TO LACK OF SHOWER/TSTM ACTIVITY TO THE SW THIS MORNING...AM NOW THINKING CONVECTION WILL BE CONFINED TO THE AFTN HOURS. TIMING OF 16Z-19Z MAY STILL BE TOO EARLY...BUT INSTABILITY IS ALREADY PRESENT ACROSS THE AREA SO IT MAY NOT TAKE LONG FOR STORMS TO DEVELOP. CONDS WILL LIKELY VARY FROM VFR TO MVFR/IFR IN CONVECTION. WINDS MAY VARY AND BE +/- 20-30 DEGREES OF CURRENT FORECAST...ESPECIALLY THIS MORNING. AS FRONT INCHES CLOSER TO THE AREA TONIGHT...SHOWERS/TSTMS WILL REMAIN A THREAT...BUT COVERAGE WILL DECREASE AND THEREFORE CONFIDENCE NOT HIGH ENOUGH TO INCLUDE AT THIS TIME. AREAS OF MVFR TO IFR IN FOG/STRATUS POSSIBLE AGAIN TONIGHT. OUTLOOK FOR 12Z SUNDAY THROUGH WEDNESDAY... .SUN... MVFR TO IFR IN THE MORNING. SCT SHOWERS/TSTMS MAINLY E OF NYC TERMINALS. .SUN NIGHT-TUE MORN...VFR. .TUE AFTN-WED...SCT SHOWERS AND TSTMS. && .MARINE... WEAK SFC TROUGH/WARM FRONTAL BOUNDARY LIFTS N OF THE WATERS LATER THIS MORNING/AFTN. MEANWHILE...A COLD FRONT AND WAVE OF LOW PRES WILL APPROACH FROM THE WEST AND SLOWLY MOVE ACROSS THE AREA SUN AND SUN NIGHT. TIGHTENING PRES GRADIENT TODAY WITH SLY WINDS 10-20 KT ON THE WATERS...HIGHEST ON THE OCEAN. GUSTS ON THE OCEAN WATERS MAY FALL SHORT OF ADVSY LEVELS THIS AFTN...BUT SEAS WILL REMAIN BETWEEN 5 AND 7 FT THROUGH TONIGHT. SCA REMAINS IN PLACE AS A RESULT. MARGINAL SEAS MAY LINGER INTO SUNDAY MORNING...MAINLY ON EASTERN OCEAN WATERS...BUT DO NOT HAVE THE CONFIDENCE TO EXTEND INTO THE THIRD PERIOD AT THIS POINT...ESPECIALLY SINCE WW3 HAS BEEN RUNNING HIGH ALL SEASON. HIGH PRES BUILDS IN FOR MONDAY INTO TUE...THEN ANOTHER FRONTAL SYSTEM WITH UNSETTLED WEATHER RETURNS FOR THE MIDDLE OF THE WEEK. SUB-ADVSY CONDS ARE EXPECTED DURING THIS TIME. && .HYDROLOGY... STILL LOOKING AT A HEAVY RAIN THREAT WITH PWATS NEAR 1.8 TO 2 INCHES FOR TODAY AND TONIGHT...ESPECIALLY FOR EASTERN SECTIONS OF THE FORECAST REGION. ADDITIONAL RAINFALL TOTALS THROUGH SUNDAY ARE BASIN AVERAGED FROM 1/2 TO 1 INCH. HIGHER AMOUNTS WILL BE POSSIBLE UP TO 2 INCHES HERE THOUGH. SIMILAR TO YESTERDAY...MINOR FLOODING SEEMS TO BE MAIN THREAT WITH ISOLATED FLASH FLOODING POSSIBLE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ350-353-355. && $$ SYNOPSIS...JM NEAR TERM...JM SHORT TERM...JM LONG TERM...MPS AVIATION...24 MARINE...24 HYDROLOGY...JM
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
732 AM EDT SAT AUG 11 2012 .SYNOPSIS... AN APPROACHING COLD FRONT WILL BRING A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH SUNDAY MORNING. THIS FRONT WILL STALL OVER THE AREA AND DISSIPATE BY MONDAY. DRIER CONDITIONS ARE EXPECTED FOR THE EARLY PART OF THE WEEK...BEFORE ANOTHER COLD FRONT BRINGS RENEWED THUNDERSTORM CHANCES LATE TUESDAY AND WEDNESDAY. MORE SEASONABLE WEATHER IS EXPECTED FOR THE END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM SATURDAY...EACH RUN OF THE HRRR HAS POOR INITIALIZATION VERSUS RADAR AND PLACES PRECIPITATION IN DIFFERENT...SEEMINGLY RANDOM...LOCATIONS THROUGHOUT THE DAY. ASIDE FROM THE CURRENT CONVECTIVE DEVELOPMENT IN THE WHITEVILLE VICINITY...UPSTREAM SATELLITE AND RADAR SHOWS LITTLE NEW ACTIVITY MOVING INTO OUR FORECAST AREA FOR THE NEXT HOUR OR TWO. WE STILL ANTICIPATE SHOWERS AND STORMS TO FILL IN LATER THIS MORNING AND ESPECIALLY INLAND THIS AFTERNOON GIVEN THE HIGHLY FAVORABLE UPPER LEVEL ENVIRONMENT...DEEP ALBEIT MODEST INSTABILITY...AND RICH MOISTURE IN THE LOW LEVELS. NO SIGNIFICANT CHANGES HAVE BEEN MADE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... THE ONLY THING NORMAL ABOUT TODAY`S WEATHER PATTERN IS HIGH HUMIDITY THROUGHOUT THE ATMOSPHERE: PRECIPITABLE WATER VALUES WILL HOVER BETWEEN 2.0 AND 2.3 INCHES THROUGH THIS EVENING. QUITE UNUSUAL FOR EARLY AUGUST IS THE OVERALL SYNOPTIC PATTERN WHICH INCLUDES A CLOSED UPPER LOW IN THE GREAT LAKES AND A STRONG TROUGH AXIS EXTENDING DOWN WEST OF THE APPALACHIANS. THIS TROUGH HAS BACKED OUR MID AND UPPER FLOW ALL THE WAY AROUND TO THE SOUTH-SOUTHWEST WITH CARIBBEAN AIR BEING PULLED NORTH INTO THE CAROLINAS. A SURFACE COLD FRONT CURRENTLY LOCATED IN THE MOUNTAINS WILL PUSH EAST AND INTO THE EASTERN CAROLINAS LATE TONIGHT. WE ARE EXPECTING GOOD COVERAGE OF SHOWERS AND THUNDERSTORMS TODAY...WITH CHANCES RANGING FROM 50-60 PERCENT ON THE SOUTH CAROLINA COAST TO 70 PERCENT ELSEWHERE. THE 21Z SATURDAY SREF QPF ENSEMBLES SHOWED THE BEST POTENTIAL FOR PRECIP TODAY IS IN THE LUMBERTON/DILLON/BENNETTSVILLE CORRIDOR WHERE I`M CONTEMPLATING AN 80 POP FOR TODAY. A FAVORABLY POSITIONED 300 MB JET STREAK EXTENDING FROM CENTRAL NC NORTH INTO NEW ENGLAND WILL PROVIDE UPPER DIVERGENCE...WHILE 25-30 KT WINDS AT 700 MB WILL PUSH STORMS ALONG AT A GOOD CLIP WITH HIGH AREAL COVERAGE EXPECTED. PLENTY OF CLOUD COVER WILL HOLD HIGHS IN THE MID TO UPPER 80S WITH TALL SKINNY CAPE PROFILES NOTED IN MODEL FORECAST SOUNDINGS. THIS LIMITED INSTABILITY SHOULD HELP HOLD SEVERE WEATHER PROBABILITIES DOWN...ALTHOUGH HEAVY RAINFALL AND LOCALIZED FLOODING WILL REMAIN POSSIBLE WHERE TRAINING STORMS OCCUR. THE 500 MB TROUGH WILL PUSH EAST AND OVERHEAD TONIGHT...THEN OFFSHORE BY DAYBREAK SUNDAY. THIS COULD BRING ONE MORE BAND OF SHOWERS AND STORMS WITH IT ALTHOUGH INSTABILITY WILL BECOME MORE LIMITED AS THE NIGHT WEARS ON. LOWS SHOULD FALL INTO THE LOWER 70S IN MOST AREAS...WITH SOME READINGS AROUND OR JUST BELOW 70 POSSIBLE WELL INLAND. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 AM SATURDAY...COLD FRONT WILL BE CROSSING THE CWA WHILE DISSIPATING EARLY SUNDAY. ALTHOUGH SOME GUIDANCE HAS THE FRONT CROSSING BEFORE THE START OF THE SHORT TERM...FAVOR THE SLOWER SOLUTIONS WHICH SHOW FROPA BY EARLY SUNDAY AFTN DUE TO SOMEWHAT BOUNDARY-PARALLEL MID LEVEL FLOW. FORECAST SOUNDINGS SUGGEST VERY DRY AIR WORKING IN FROM WEST TO EAST BEHIND THE FRONT...SO ANY PRECIP EARLY SUNDAY WILL FADE BY AFTN AND MUCH OF SUNDAY WILL BE PRETTY NICE WITH INCREASING SUNSHINE. DRY WESTERLY FLOW PERSISTS SUNDAY NIGHT AND MONDAY WITH PWATS FALLING TO BELOW ONE INCH. THIS COMBINED WITH A CONVECTIVE LID NEAR 800MB WILL PREVENT ANY CONVECTION MONDAY...AND WILL DROP INHERITED SCHC TO SILENT. TEMPS SUNDAY WILL BE AT OR SLIGHTLY BELOW CLIMO WITH SOME WEAK COOL AIR ADVECTION...BUT AMPLE AUGUST SUNSHINE WILL HELP RAISE TEMPS TO AROUND 90 DURING THE AFTN...FALLING TO AROUND 70 SUNDAY NIGHT. SIMILAR ON MONDAY...IF NOT A TOUCH WARMER...WITH LOWS ONCE AGAIN AROUND 70. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 300 AM SATURDAY...BROAD UPPER TROUGHING PERSISTS THROUGH THURSDAY ACROSS THE SOUTHEAST BEFORE 500MB RIDGE BEGINS TO WORK BACK INTO THE AREA FOR FRIDAY. UPPER TROUGH AND HENCE SLIGHTLY LOWER 1000-500MB THICKNESSES WOULD GENERALLY SUGGEST MODERATE DIURNAL CONVECTIVE CHANCES DURING THE SUMMER...BUT OVERALL DO NOT ANTICIPATE WIDESPREAD STORMS THROUGH MUCH OF THE PERIOD. THE EXCEPTION WILL BE LATE TUESDAY AND WEDNESDAY AS A SHORTWAVE ROTATES DOWN THROUGH THE BASE OF THE TROUGH AND DRIVES A COLD FRONT TOWARDS THE ILM CWA. WINDS AHEAD OF THIS FEATURE FINALLY TURN SW ON TUESDAY...HELPING TO FORCE THE MID LEVEL THETA-E RIDGE INTO THE MID-ATLANTIC...SERVING AS THE FUEL FOR STORMS ALONG AND AHEAD OF THE COLD FRONT. TOO EARLY TO GET VERY SPECIFIC IN THE DETAILS...BUT WILL CARRY CHC POP BEGINNING LATE TUESDAY AND THROUGH WEDNESDAY FOR TSTMS. FRONT PUSHES OFFSHORE LATE WEDNESDAY LEADING TO DRIER AND COOLER CONDITIONS THURSDAY...BEFORE RIDGING DEVELOPS ALOFT FOR THE END OF THE WEEK. TEMPS WILL BE RIGHT AROUND CLIMO MOST DAYS...POTENTIALLY WARMING TO ABOVE CLIMO BY FRIDAY DUE TO INCREASING THICKNESSES AND RETURN OF SW RETURN FLOW. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 12Z...EXPECT SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS TO DEVELOP DURING THE PERIOD. WHILE SHOWERS AND STORMS ARE POSSIBLE THROUGHOUT THE FORECAST PERIOD...THEY ARE MOST PROBABLE DURING THE 12 HOURS FROM APPROXIMATELY 18Z THROUGH 06Z. INTERMITTENT STORMS WILL BE ACCOMPANIED BY MVFR OR SHORT DURATION IFR CONDITIONS. S TO SW WINDS OF 10 TO 15 KT THIS AM WILL DIMINISH TO 5 TO 10 KT THIS AFTERNOON. EXTENDED OUTLOOK...CHANCE OF MORNING MVFR VSBYS IN BR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH SUNDAY. VFR MONDAY THROUGH WED...OUTSIDE POSSIBLE SHOWERS AND STORMS TUESDAY NIGHT INTO WED. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM SATURDAY...WINDS ARE DECREASING AS THE GRADIENT UNWINDS ON THE WESTERN PERIPHERY OF THE BERMUDA HIGH. THE SMALL CRAFT ADVISORY SHOULD BE ABLE TO EXPIRE ON-SCHEDULE IN JUST A COUPLE OF HOURS. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... STRONG SOUTH-SOUTHWEST WINDS THIS MORNING ARE THE RESULT OF A PINCHED GRADIENT ALONG THE WESTERN EXTENT OF THE BERMUDA HIGH. A SURFACE COLD FRONT HAS PUSHED INTO THE SOUTHERN APPALACHIANS...AND THIS BOUNDARY WILL MOVE EAST AND INTO THE EASTERN CAROLINAS LATE TONIGHT. SOUTH TO SOUTHWEST WINDS WILL CONTINUE THROUGH TONIGHT...ALTHOUGH THE STRONGEST WIND SPEEDS ARE EXPECTED NOW THROUGH DAYBREAK IN ASSOCIATION WITH A LOW LEVEL JET STREAM OVERHEAD. SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO BE FAIRLY WIDESPREAD THIS MORNING ACROSS THE COASTAL WATERS...WITH SOME DECREASE IN COVERAGE EXPECTED THIS AFTERNOON. AS THE MAIN UPPER LEVEL TROUGH MOVES OUT ACROSS THE WATERS LATE TONIGHT THERE COULD BE A SECOND WAVE OF ACTIVITY MOVING OFFSHORE...ESPECIALLY NORTH OF MYRTLE BEACH. SEAS CURRENTLY RANGE FROM 4-5 FT AT THE CAPE FEAR AREA BUOYS...IN-LINE WITH PREVIOUS FORECASTS. NO CHANGES ARE PLANNED AT THIS TIME TO THE PREVIOUSLY ISSUED SMALL CRAFT ADVISORY. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 300 AM SATURDAY...COLD FRONT WILL BE SLOWLY MOVING ACROSS THE AREA AT THE START OF THE PERIOD...WHILE AT THE SAME TIME WEAKENING. SW WINDS OF 10-15 KTS THROUGH SUNDAY WILL GRADUALLY VEER TO THE WEST AND EASE BY EARLY MONDAY AS FRONT WASHES OUT OVER THE WATERS. THESE WINDS WILL CREATE 3-4 FT SEAS SUNDAY AS THEY WORK IN TANDEM WITH AN INCREASING 2FT/9SEC SE SWELL. ALTHOUGH THE SE SWELL WILL PERSIST ON MONDAY...WAVE HEIGHTS WILL GRADUALLY DECAY DUE TO THE DECREASING WINDS...FALLING TO 2-3 FT THROUGH MONDAY NIGHT. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 300 AM SATURDAY...BERMUDA HIGH PRESSURE WILL CONTROL THE SYNOPTIC FLOW TUESDAY...BEFORE A COLD FRONT WORKS THROUGH THE AREA ON WEDNESDAY. THESE TWO FEATURES COMBINE TO CREATE INCREASING SW WINDS BY TUESDAY NIGHT...RISING FROM AROUND 10 KTS EARLY TUESDAY...TO AS MUCH AS 20 KTS BY EARLY WEDNESDAY...THANKS TO THE TIGHTENING PRESSURE GRADIENT AHEAD OF THE COLD FRONT. THESE WINDS FORCE RAPIDLY BUILDING WIND-WAVES...BECOMING 3-5 FT TUESDAY NIGHT AND EARLY WEDNESDAY...AND A SCEC MAY BE NEEDED FOR A TIME. FRONT WILL CROSS WEDNESDAY WHILE WEAKENING...AND WINDS WILL SLOWLY VEER TO THE WEST BY LATE WEDNESDAY WHILE EASING TO AROUND 10 KTS. SEAS FALL IN RESPONSE...BECOMING 2-3 FT BY THE END OF THE PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EDT THIS MORNING FOR AMZ250- 252. && $$ SYNOPSIS...JDW NEAR TERM...TRA SHORT TERM...JDW LONG TERM...JDW AVIATION...RAN
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
651 AM EDT SAT AUG 11 2012 .SYNOPSIS... AN APPROACHING COLD FRONT WILL BRING A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH SUNDAY MORNING. THIS FRONT WILL STALL OVER THE AREA AND DISSIPATE BY MONDAY. DRIER CONDITIONS EXPECTED FOR THE EARLY PART OF THE WEEK...BEFORE ANOTHER COLD FRONT WILL BRING RENEWED THUNDERSTORM CHANCES LATE TUESDAY AND WEDNESDAY. MORE SEASONABLE WEATHER EXPECTED FOR THE END OF THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM SATURDAY...EACH RUN OF THE HRRR HAS POOR INITIALIZATION VERSUS RADAR AND PLACES PRECIPITATION IN DIFFERENT...SEEMINGLY RANDOM...LOCATIONS THROUGHOUT THE DAY. ASIDE FROM THE CURRENT CONVECTIVE DEVELOPMENT IN THE WHITEVILLE VICINITY...UPSTREAM SATELLITE AND RADAR SHOWS LITTLE NEW ACTIVITY MOVING INTO OUR FORECAST AREA FOR THE NEXT HOUR OR TWO. WE STILL ANTICIPATE SHOWERS AND STORMS TO FILL IN LATER THIS MORNING AND ESPECIALLY INLAND THIS AFTERNOON GIVEN THE HIGHLY FAVORABLE UPPER LEVEL ENVIRONMENT...DEEP ALBEIT MODEST INSTABILITY...AND RICH MOISTURE IN THE LOW LEVELS. NO SIGNIFICANT CHANGES HAVE BEEN MADE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... THE ONLY THING NORMAL ABOUT TODAY`S WEATHER PATTERN IS HIGH HUMIDITY THROUGHOUT THE ATMOSPHERE: PRECIPITABLE WATER VALUES WILL HOVER BETWEEN 2.0 AND 2.3 INCHES THROUGH THIS EVENING. QUITE UNUSUAL FOR EARLY AUGUST IS THE OVERALL SYNOPTIC PATTERN WHICH INCLUDES A CLOSED UPPER LOW IN THE GREAT LAKES AND A STRONG TROUGH AXIS EXTENDING DOWN WEST OF THE APPALACHIANS. THIS TROUGH HAS BACKED OUR MID AND UPPER FLOW ALL THE WAY AROUND TO THE SOUTH-SOUTHWEST WITH CARIBBEAN AIR BEING PULLED NORTH INTO THE CAROLINAS. A SURFACE COLD FRONT CURRENTLY LOCATED IN THE MOUNTAINS WILL PUSH EAST AND INTO THE EASTERN CAROLINAS LATE TONIGHT. WE ARE EXPECTING GOOD COVERAGE OF SHOWERS AND THUNDERSTORMS TODAY...WITH CHANCES RANGING FROM 50-60 PERCENT ON THE SOUTH CAROLINA COAST TO 70 PERCENT ELSEWHERE. THE 21Z SATURDAY SREF QPF ENSEMBLES SHOWED THE BEST POTENTIAL FOR PRECIP TODAY IS IN THE LUMBERTON/DILLON/BENNETTSVILLE CORRIDOR WHERE I`M CONTEMPLATING AN 80 POP FOR TODAY. A FAVORABLY POSITIONED 300 MB JET STREAK EXTENDING FROM CENTRAL NC NORTH INTO NEW ENGLAND WILL PROVIDE UPPER DIVERGENCE...WHILE 25-30 KT WINDS AT 700 MB WILL PUSH STORMS ALONG AT A GOOD CLIP WITH HIGH AREAL COVERAGE EXPECTED. PLENTY OF CLOUD COVER WILL HOLD HIGHS IN THE MID TO UPPER 80S WITH TALL SKINNY CAPE PROFILES NOTED IN MODEL FORECAST SOUNDINGS. THIS LIMITED INSTABILITY SHOULD HELP HOLD SEVERE WEATHER PROBABILITIES DOWN...ALTHOUGH HEAVY RAINFALL AND LOCALIZED FLOODING WILL REMAIN POSSIBLE WHERE TRAINING STORMS OCCUR. THE 500 MB TROUGH WILL PUSH EAST AND OVERHEAD TONIGHT...THEN OFFSHORE BY DAYBREAK SUNDAY. THIS COULD BRING ONE MORE BAND OF SHOWERS AND STORMS WITH IT ALTHOUGH INSTABILITY WILL BECOME MORE LIMITED AS THE NIGHT WEARS ON. LOWS SHOULD FALL INTO THE LOWER 70S IN MOST AREAS...WITH SOME READINGS AROUND OR JUST BELOW 70 POSSIBLE WELL INLAND. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 300 AM SATURDAY...COLD FRONT WILL BE CROSSING THE CWA WHILE DISSIPATING EARLY SUNDAY. ALTHOUGH SOME GUIDANCE HAS THE FRONT CROSSING BEFORE THE START OF THE SHORT TERM...FAVOR THE SLOWER SOLUTIONS WHICH SHOW FROPA BY EARLY SUNDAY AFTN DUE TO SOMEWHAT BOUNDARY-PARALLEL MID LEVEL FLOW. FORECAST SOUNDINGS SUGGEST VERY DRY AIR WORKING IN FROM WEST TO EAST BEHIND THE FRONT...SO ANY PRECIP EARLY SUNDAY WILL FADE BY AFTN AND MUCH OF SUNDAY WILL BE PRETTY NICE WITH INCREASING SUNSHINE. DRY WESTERLY FLOW PERSISTS SUNDAY NIGHT AND MONDAY WITH PWATS FALLING TO BELOW ONE INCH. THIS COMBINED WITH A CONVECTIVE LID NEAR 800MB WILL PREVENT ANY CONVECTION MONDAY...AND WILL DROP INHERITED SCHC TO SILENT. TEMPS SUNDAY WILL BE AT OR SLIGHTLY BELOW CLIMO WITH SOME WEAK COOL AIR ADVECTION...BUT AMPLE AUGUST SUNSHINE WILL HELP RAISE TEMPS TO AROUND 90 DURING THE AFTN...FALLING TO AROUND 70 SUNDAY NIGHT. SIMILAR ON MONDAY...IF NOT A TOUCH WARMER...WITH LOWS ONCE AGAIN AROUND 70. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 300 AM SATURDAY...BROAD UPPER TROUGHING PERSISTS THROUGH THURSDAY ACROSS THE SOUTHEAST BEFORE 500MB RIDGE BEGINS TO WORK BACK INTO THE AREA FOR FRIDAY. UPPER TROUGH AND HENCE SLIGHTLY LOWER 1000-500MB THICKNESSES WOULD GENERALLY SUGGEST MODERATE DIURNAL CONVECTIVE CHANCES DURING THE SUMMER...BUT OVERALL DO NOT ANTICIPATE WIDESPREAD STORMS THROUGH MUCH OF THE PERIOD. THE EXCEPTION WILL BE LATE TUESDAY AND WEDNESDAY AS A SHORTWAVE ROTATES DOWN THROUGH THE BASE OF THE TROUGH AND DRIVES A COLD FRONT TOWARDS THE ILM CWA. WINDS AHEAD OF THIS FEATURE FINALLY TURN SW ON TUESDAY...HELPING TO FORCE THE MID LEVEL THETA-E RIDGE INTO THE MID-ATLANTIC...SERVING AS THE FUEL FOR STORMS ALONG AND AHEAD OF THE COLD FRONT. TOO EARLY TO GET VERY SPECIFIC IN THE DETAILS...BUT WILL CARRY CHC POP BEGINNING LATE TUESDAY AND THROUGH WEDNESDAY FOR TSTMS. FRONT PUSHES OFFSHORE LATE WEDNESDAY LEADING TO DRIER AND COOLER CONDITIONS THURSDAY...BEFORE RIDGING DEVELOPS ALOFT FOR THE END OF THE WEEK. TEMPS WILL BE RIGHT AROUND CLIMO MOST DAYS...POTENTIALLY WARMING TO ABOVE CLIMO BY FRIDAY DUE TO INCREASING THICKNESSES AND RETURN OF SW RETURN FLOW. && .AVIATION /07Z SATURDAY THROUGH WEDNESDAY/... AS OF 06Z...MOD CONFIDENCE RW W/TEMPO MVFR CONDS WILL OCCUR AT THE COAST THRU 08-10Z AND AT FLO/LBT 08-12Z. ISOLD TS PSBL MAINLY AT THE COAST. CONFIDENCE LOW ON TIMING THUS HAVE USED PROB30 GROUPS FOR THUNDERSTORMS/IFR AFT 15Z. TIMING BASED ON BEST GFS VERTICAL VELOCITIES. EXTENDED OUTLOOK...CHANCE OF MORNING MVFR VSBYS IN BR WITH A CHANCE OF SHOWERS AND THUNDERSTORMS THROUGH SUNDAY. VFR MONDAY THROUGH WED. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM SATURDAY...WINDS ARE DECREASING AS THE GRADIENT UNWINDS ON THE WESTERN PERIPHERY OF THE BERMUDA HIGH. THE SMALL CRAFT ADVISORY SHOULD BE ABLE TO EXPIRE ON-SCHEDULE IN JUST A COUPLE OF HOURS. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... STRONG SOUTH-SOUTHWEST WINDS THIS MORNING ARE THE RESULT OF A PINCHED GRADIENT ALONG THE WESTERN EXTENT OF THE BERMUDA HIGH. A SURFACE COLD FRONT HAS PUSHED INTO THE SOUTHERN APPALACHIANS...AND THIS BOUNDARY WILL MOVE EAST AND INTO THE EASTERN CAROLINAS LATE TONIGHT. SOUTH TO SOUTHWEST WINDS WILL CONTINUE THROUGH TONIGHT...ALTHOUGH THE STRONGEST WIND SPEEDS ARE EXPECTED NOW THROUGH DAYBREAK IN ASSOCIATION WITH A LOW LEVEL JET STREAM OVERHEAD. SHOWER AND THUNDERSTORM ACTIVITY IS EXPECTED TO BE FAIRLY WIDESPREAD THIS MORNING ACROSS THE COASTAL WATERS...WITH SOME DECREASE IN COVERAGE EXPECTED THIS AFTERNOON. AS THE MAIN UPPER LEVEL TROUGH MOVES OUT ACROSS THE WATERS LATE TONIGHT THERE COULD BE A SECOND WAVE OF ACTIVITY MOVING OFFSHORE...ESPECIALLY NORTH OF MYRTLE BEACH. SEAS CURRENTLY RANGE FROM 4-5 FT AT THE CAPE FEAR AREA BUOYS...IN-LINE WITH PREVIOUS FORECASTS. NO CHANGES ARE PLANNED AT THIS TIME TO THE PREVIOUSLY ISSUED SMALL CRAFT ADVISORY. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 300 AM SATURDAY...COLD FRONT WILL BE SLOWLY MOVING ACROSS THE AREA AT THE START OF THE PERIOD...WHILE AT THE SAME TIME WEAKENING. SW WINDS OF 10-15 KTS THROUGH SUNDAY WILL GRADUALLY VEER TO THE WEST AND EASE BY EARLY MONDAY AS FRONT WASHES OUT OVER THE WATERS. THESE WINDS WILL CREATE 3-4 FT SEAS SUNDAY AS THEY WORK IN TANDEM WITH AN INCREASING 2FT/9SEC SE SWELL. ALTHOUGH THE SE SWELL WILL PERSIST ON MONDAY...WAVE HEIGHTS WILL GRADUALLY DECAY DUE TO THE DECREASING WINDS...FALLING TO 2-3 FT THROUGH MONDAY NIGHT. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 300 AM SATURDAY...BERMUDA HIGH PRESSURE WILL CONTROL THE SYNOPTIC FLOW TUESDAY...BEFORE A COLD FRONT WORKS THROUGH THE AREA ON WEDNESDAY. THESE TWO FEATURES COMBINE TO CREATE INCREASING SW WINDS BY TUESDAY NIGHT...RISING FROM AROUND 10 KTS EARLY TUESDAY...TO AS MUCH AS 20 KTS BY EARLY WEDNESDAY...THANKS TO THE TIGHTENING PRESSURE GRADIENT AHEAD OF THE COLD FRONT. THESE WINDS FORCE RAPIDLY BUILDING WIND-WAVES...BECOMING 3-5 FT TUESDAY NIGHT AND EARLY WEDNESDAY...AND A SCEC MAY BE NEEDED FOR A TIME. FRONT WILL CROSS WEDNESDAY WHILE WEAKENING...AND WINDS WILL SLOWLY VEER TO THE WEST BY LATE WEDNESDAY WHILE EASING TO AROUND 10 KTS. SEAS FALL IN RESPONSE...BECOMING 2-3 FT BY THE END OF THE PERIOD. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EDT THIS MORNING FOR AMZ250- 252. && $$ SYNOPSIS...JDW NEAR TERM...TRA SHORT TERM...JDW LONG TERM...JDW AVIATION...TRA MARINE...TRA/JDW
AREA FORECAST DISCUSSION
NWS NORMAN OK
637 AM CDT SAT AUG 11 2012 .DISCUSSION... AVIATION DISCUSSION FOR THE 12Z TAFS IS BELOW. && .AVIATION... VFR CONDITIONS ARE EXPECTED TO CONTINUE. A FEW -SHRA WILL CONTINUE TO AFFECT WESTERN OKLAHOMA THROUGH 15Z BEFORE DISSIPATING. ADDITIONAL -SHRA/-TSRA MAY DEVELOP MAINLY AFTER 00Z...BUT DID NOT MENTION DUE TO VERY LOW CONFIDENCE OF OCCURRENCE. SOUTH/SOUTHEAST WINDS WILL BECOME GUSTY ACROSS WESTERN OKLAHOMA BY 16Z. MBS && .PREV DISCUSSION... /ISSUED 422 AM CDT SAT AUG 11 2012/ DISCUSSION... THE FIRST CONCERN IS ELEVATED TO CRITICAL FIRE WEATHER CONDITIONS ESPECIALLY TODAY OVER NORTHWEST OKLAHOMA...THEN HOT WEATHER AND RAIN CHANCES ARE THE NEXT CONCERNS. THIS MORNING...A FEW HIGH BASED SHOWERS AND THUNDERSTORMS WILL AFFECT FAR WESTERN OKLAHOMA AND BRING LIGHT AMOUNTS OF RAINFALL. BASED ON THE LATEST HRRR OUTPUT...THIS ACTIVITY WILL DIMINISH AFTER 9 AM. KEPT 20 PERCENT CHANCE WEST OF AN ALVA TO ALTUS LINE TO ACCOUNT FOR THIS. OTHERWISE...DRY AND COOLER CONDITIONS WILL PREVAIL. A FEW LOCATIONS NEAR EL RENO AND ADA HAVE DROPPED TO THE UPPER 50S EARLY THIS MORNING. THIS AFTERNOON WILL BE PARTLY TO MOSTLY SUNNY AND ABOUT 2 TO 5 DEGREES WARMER THAN YESTERDAY. PREFERRED THE HOTTER 00Z METMOS HIGHS. SOUTHERLY WINDS WILL INCREASE OVER WESTERN OKLAHOMA. TONIGHT...INCREASING CLOUDS AND WINDS WILL ALLOW FOR WARMER CONDITIONS. KEPT 20 PERCENT CHANCE MAINLY OVER NORTHERN OKLAHOMA AS A FEW HIGH BASED SHOWERS AND STORMS MAY DEVELOP...THOUGH CONFIDENCE IS NOT THE GREATEST. ANY RAINFALL WILL BE LIGHT. SUNDAY...VERY HOT TEMPERATURES AND A FEW AFTERNOON AND EVENING SEVERE THUNDERSTORMS REMAIN THE BIG CONCERNS. TRIPLE DIGIT HEAT IS EXPECTED ACROSS MOST...IF NOT ALL...OF THE AREA WITH HIGHS POSSIBLY APPROACHING 110 DEGREES OVER SOUTHWEST OKLAHOMA AND WESTERN NORTH TEXAS. WENT NEAR OR SLIGHTLY ABOVE 00Z METMOS HIGHS. HEAT INDICES MAY APPROACH 105 DEGREES SOUTH OF AN ALTUS TO STILLWATER LINE...SO A HEAT ADVISORY MAY BE NECESSARY. AS FOR SEVERE THUNDERSTORM POTENTIAL SUNDAY AFTERNOON AND EVENING...LATEST NAM12 RUNS SUGGESTED A FEW HIGH BASED THUNDERSTORMS WILL DEVELOP NEAR A FRONT...SOMEWHERE NEAR A VERNON TO OKLAHOMA CITY LINE 1 TO 4 PM CDT...THEN MOVE SOUTHEAST. DUE TO MODERATE SHEAR AND INSTABILITY...A FEW DAMAGING WIND GUSTS OVER 60 MPH WOULD BE THE MAIN HAZARD. BELIEVE ANY SEVERE THREAT WOULD DIMINISH BY MIDNIGHT. MONDAY THROUGH WEDNESDAY...MAINLY HOT AND DRY CONDITIONS ARE EXPECTED...THOUGH CONFIDENCE IS DECREASING TUESDAY AND WEDNESDAY AS CLOUDS AND INCREASING MID LEVEL MOISTURE MAY ALLOW FOR SOME STORMS AND COOLER TEMPERATURES. FOR NOW...DID NOT MAKE MANY CHANGES DURING THIS TIME FRAME. THURSDAY AND FRIDAY...A SIGNIFICANT COOLDOWN WITH INCREASING RAIN CHANCES MAY OCCUR WITH THE PASSAGE OF A COLD FRONT AS LATEST MODELS WERE IN DECENT AGREEMENT. MBS FIRE WEATHER... UPGRADED THE FIRE WEATHER WATCH TO A RED FLAG WARNING ACROSS WEST CENTRAL AND NORTHWEST OKLAHOMA DUE TO MODERATE CONFIDENCE THAT CRITICAL FIRE WEATHER CONDITIONS WILL BE MET. WINDS WILL BE MARGINAL. ANY RAINFALL IN THE WARNED AREA THIS MORNING WILL BE ISOLATED AND VERY LIGHT...WHICH IS NOT EXPECTED TO HAVE ANY SUBSTANTIAL EFFECT ON THE IGNITION OF WILDFIRES. ELEVATED TO NEAR CRITICAL FIRE WEATHER CONDITIONS WILL CONTINUE THROUGH AT LEAST MIDWEEK. THERE IS A LOW CHANCE FOR NEAR CRITICAL FIRE WEATHER CONDITIONS NEAR A WICHITA FALLS TO OKLAHOMA CITY TO STILLWATER LINE SUNDAY AFTERNOON. DUE TO MARGINAL WINDS MAINLY UNDER 20 MPH AND HUMIDITY LEVELS ABOVE 20 PERCENT... DID NOT ISSUE A FIRE WEATHER WATCH. WEDNESDAY MAY HAVE A HIGHER CHANCE FOR CRITICAL FIRE WEATHER CONDITIONS ACROSS THE AREA. MBS && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 97 75 103 73 / 0 10 20 20 HOBART OK 99 74 103 72 / 20 10 10 10 WICHITA FALLS TX 101 76 108 76 / 0 10 20 20 GAGE OK 97 71 102 67 / 20 20 10 0 PONCA CITY OK 97 75 102 68 / 0 20 20 20 DURANT OK 96 73 102 74 / 0 10 20 30 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 10 PM CDT THIS EVENING FOR OKZ004-005-009-010-014>016-021-022. TX...NONE. && $$ 25/17/17
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
1015 AM CDT SAT AUG 11 2012 .UPDATE... JUST A QUICK UPDATE TO EXPAND COVERAGE OF LIGHT RAIN SHOWERS. MOST AREAS HAVE ONLY RECEIVED A FEW HUNDREDTHS THUS FAR...WITH A DRY LAYER BELOW 10KFT. SOME DIFFERENCES IN MODEL TIMING HAVE ARISEN WITH THIS MORNINGS SUITE OF GUIDANCE...THE HRRR PUSHING THE SYSTEM THROUGH QUICKLY...WHILE THE NAM/SREF/GFS A MUCH SLOWER PROGRESSION. AT THIS POINT...WILL NOT TINKER WITH THE TIMING/COVERAGE FOR THIS EVENING/OVERNIGHT GIVEN UNCERTAINTY. DO EXPECT THAT AS WE CONTINUE TO MOISTEN UP THE DRY LAYER...AND THE ASSOCIATED WAVE STRENGTHENS OVER WESTERN SOUTH DAKOTA...PRECIPITATION WILL INTENSITY AND INCREASE IN COVERAGE. ALSO DROPPED HIGH TEMPERATURES A FEW DEGREES WITH WIDESPREAD CLOUD COVER/RAIN. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH MONDAY CHILLY AND GENERALLY WET CONDITIONS ARE EXPECTED FOR THE WEEKEND ACROSS THE NORTHERN PLAINS. THE AREA OF HIGH PRESSURE THAT BROUGHT SEASONALLY COOL CONDITIONS TO THE EASTERN DAKOTAS FOR THE PAST FEW DAYS WILL GRADUALLY BE REPLACED BY A LOW PRESSURE SYSTEM. THIS LOW PRESSURE SYSTEM WILL HAVE SOME DRY AIR TO OVER COME BELOW 700 MB...WITH MODELS NOW PCPN REACHING THE I-29 CORRIDOR CLOSER TO 0Z SUNDAY. THIS SLOW PROGRESSION SEEMS PRETTY LIKELY GIVEN SHOWERS HAVE BEEN ONGOING ALL NIGHT IN WESTERN SD...WITH LITTLE ADVANCEMENT TOWARD THIS CWA. THE BEST TIMING FOR PCPN FOR THE CWA APPEARS TO BE TONIGHT THROUGH SUNDAY. MODELS ARE SUGGESTING THE SURFACE AND UPPER LEVEL LOW WILL BE NEARLY VERTICALLY STACKED OVER SOUTHERN SD WITH DECENT WAA FLOW WRAPPING NORTHWARD INTO THIS CWA. WITH 850 MB TEMPS ONLY IN THE LOWER TEENS...ALONG WITH CLOUDY SKIES...HIGH TEMPERATURES ON SUNDAY WILL LIKELY STRUGGLE TO REACH THE MID 60S IN THE EASTERN HALF OF THE CWA. THE LOW PRESSURE SHOULD FINALLY EXIT THE REGION BY MONDAY MORNING...WITH DRY CONDITIONS EXPECTED TO START THE WORK WEEK. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY MAIN FORECAST CHALLENGE DURING THE EXTENDED WILL BE THE SFC COLD FRONT THAT WILL MOVE THROUGH THE DAKOTAS MID WEEK. ENHANCED BY SHORTWAVE ACTIVITY AND WITH GOOD SHEAR...SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TUESDAY NIGHT THROUGH WEDNESDAY. H85 TEMPS IN THE LOWER 20S WILL PLUMMET INTO THE UPPER SINGLE DIGITS BEHIND THE FRONT. TEMPERATURES NEAR NORMAL AT THE START OF THE PERIOD WILL FALL TO 5 TO 10 DEGREES BELOW AVERAGE THURSDAY THROUGH SATURDAY. && .AVIATION... 12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. HOWEVER A SYSTEM WILL APPROACH FROM THE WEST THROUGH TODAY. SHOWERS WILL BE POSSIBLE FIRST AROUND KPIR/KMBG TOWARD MORNING...THOSE SHOWERS SHOULD PUSH EAST TO KABR/KATY BY THIS AFTERNOON/EVENING AND LINGER NEAR KATY THROUGH SUNDAY MORNING. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...CONNELLY SHORT TERM...SD LONG TERM...WISE AVIATION...WISE WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS GOODLAND KS
200 PM MDT SAT AUG 11 2012 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 108 PM MDT SAT AUG 11 2012 PRE-FRONTAL TROUGH AND ASSOCIATED WIND SHIFT LINE HAS MOVED INTO THE FAR WESTERN PART OF THE FORECAST AREA. WATER VAPOR IMAGERY SHOWS SHORT WAVE TROUGH CURRENTLY MOVING ACROSS SOUTHEAST WYOMING. ALTHOUGH THE STRONGEST PART OF THE WAVE WILL BE NORTH OF FORECAST AREA...THERE WILL BE ENOUGH DIFFERENTIAL CYCLONIC VORTICITY ADVECTION TO PRODUCE SCATTERED CONVECTION. LATEST GFS IS SLIGHTLY SLOWER WITH FEATURE...BUT STILL ON TRACK FOR SCATTERED PRECIPITATION CHANCES TONIGHT. KFTG RADAR IS SHOWING SIGNS OF CONVECTIVE DEVELOPMENT NORTH OF KLIC. LATEST RUN OF THE HRRR MODEL CONTINUES TO PRODUCE SCATTERED THUNDERSTORMS OVER EASTERN COLORADO FROM 21Z-23Z...WITH STORMS MOVING OVER THE REST OF THE AREA AFTER THAT TIME. HRRR MAY BE OVERDONE WITH THE AMOUNT OF COVERAGE...BUT HAS THE GENERAL IDEA. BOTH THE NAM/GFS ALSO SHOW CONVECTION ADVECTING OVER MOST OF THE AREA. THEREFORE...WILL CONTINUE WITH SCATTERED POPS THROUGH MIDNIGHT. AS MENTIONED EARLIER...LOW LEVEL SHEAR IS MINIMAL. SOUNDING PROFILES...HOWEVER..HAVE AN INVERTED-V SIGNATURE. SO...SOME CONVECTIVE WIND GUSTS WILL APPROACH SEVERE LIMITS...THOUGH WOULD LIKE TO SEE A LITTLE MORE IMPRESSIVE DOWNDRAFT CAPE. 700 MB THETA/E AXIS WILL EXTEND FROM GOODLAND TO HASTINGS THIS EVENING...SO A FEW STORMS MAY PRODUCE BRIEF HEAVY RAIN. COLD FRONT AND DRIER AIR WILL MOVE ACROSS THE AREA AFTER 06Z. 1000/500 MB THICKNESS VALUES DROP...BUT NOT IMPRESSIVELY. WILL ONLY COOL TEMPERATURES SEVERAL DEGREES TONIGHT AND SUNDAY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 200 PM MDT SAT AUG 11 2012 SUNDAY NIGHT-MONDAY NIGHT...DRY SUNDAY NIGHT UNDER HIGH PRESSURE WITH JUST A FEW CLOUDS. LOWS IN THE 50S. ON MONDAY A WEATHER DISTURBANCE ENTERS THE SOUTHWEST AND WESTERN PORTION OF THE FORECAST AREA MOVING EAST/SOUTHEAST ACROSS THE REMAINDER OF THE AREA MONDAY NIGHT. THERE WILL BE A SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS WITH ITS PASSAGE. HIGH TEMPERATURES MONDAY IN THE MID 80S TO AROUND 90 WITH OVERNIGHT LOWS MONDAY NIGHT IN THE UPPER 50S TO LOW 60S. TUESDAY...DRY WEATHER EXPECTED. NOT REAL CONFIDENT IN PRECIP CHANCES TUESDAY NIGHT GIVEN RATHER POOR MOISTURE AVAILABILITY ACROSS THE AREA. HIGHS IN THE LOW TO MID 90S. WEDNESDAY...COVERAGE OF SHOWERS AND THUNDERSTORMS INCREASES THROUGH WEDNESDAY NIGHT AS AN UPPER LEVEL TROUGH AND COLD FRONT MOVE ACROSS THE AREA. HIGHS IN THE UPPER 80S TO LOW 90S WITH LOWS WEDNESDAY NIGHT IN THE UPPER 50S TO MID 60S. THURSDAY...MAY SEE SOME LINGERING PRECIPITATION DURING THE DAY BEFORE MOISTURE AVAILABILITY DECREASES AS SFC HIGH MOVES IN THURSDAY NIGHT. HIGHS IN THE MID 70S TO LOW 80S. OVERNIGHT LOWS IN THE MID TO UPPER 50S. FRIDAY-SATURDAY...UPPER RIDGE REBUILDS ACROSS THE INTERMOUNTAIN WEST THROUGH THE PERIOD. MOISTURE AVAILABILITY FOR PRECIPITATION LOOKS PRETTY LOW AS IS CONFIDENCE IN PRECIPITATION CHANCES. HIGHS ON FRIDAY IN THE LOW 80S...WARMING INTO THE UPPER 80S TO AROUND 90. OVERNIGHT LOWS IN THE MID 50S TO AROUND 60. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1040 AM MDT SAT AUG 11 2012 CONVECTION WILL DEVELOP OVER EASTERN COLORADO AROUND 21Z...AND THEN MOVE EAST. BASED ON SHORT RANGE MODELS...THUNDERSTORMS WILL LIKELY MOVE ACROSS KGLD BETWEEN 23Z-01Z. CONFIDENCE IS NOT AS HIGH AT KMCK...SO INDICATED THUNDERSTORMS IN VICINITY OF THAT LOCATION BETWEEN 01Z-03Z. SOUTH SURFACE WINDS 15-25 KNOTS WILL SWITCH TO THE NORTHWEST BEHIND A WEAK COLD FRONT AFTER 00Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...MENTZER LONG TERM...99 AVIATION...MENTZER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
108 PM MDT SAT AUG 11 2012 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 108 PM MDT SAT AUG 11 2012 PRE-FRONTAL TROUGH AND ASSOCIATED WIND SHIFT LINE HAS MOVED INTO THE FAR WESTERN PART OF THE FORECAST AREA. WATER VAPOR IMAGERY SHOWS SHORT WAVE TROUGH CURRENTLY MOVING ACROSS SOUTHEAST WYOMING. ALTHOUGH THE STRONGEST PART OF THE WAVE WILL BE NORTH OF FORECAST AREA...THERE WILL BE ENOUGH DIFFERENTIAL CYCLONIC VORTICITY ADVECTION TO PRODUCE SCATTERED CONVECTION. LATEST GFS IS SLIGHTLY SLOWER WITH FEATURE...BUT STILL ON TRACK FOR SCATTERED PRECIPITATION CHANCES TONIGHT. KFTG RADAR IS SHOWING SIGNS OF CONVECTIVE DEVELOPMENT NORTH OF KLIC. LATEST RUN OF THE HRRR MODEL CONTINUES TO PRODUCE SCATTERED THUNDERSTORMS OVER EASTERN COLORADO FROM 21Z-23Z...WITH STORMS MOVING OVER THE REST OF THE AREA AFTER THAT TIME. HRRR MAY BE OVERDONE WITH THE AMOUNT OF COVERAGE...BUT HAS THE GENERAL IDEA. BOTH THE NAM/GFS ALSO SHOW CONVECTION ADVECTING OVER MOST OF THE AREA. THEREFORE...WILL CONTINUE WITH SCATTERED POPS THROUGH MIDNIGHT. AS MENTIONED EARLIER...LOW LEVEL SHEAR IS MINIMAL. SOUNDING PROFILES...HOWEVER..HAVE AN INVERTED-V SIGNATURE. SO...SOME CONVECTIVE WIND GUSTS WILL APPROACH SEVERE LIMITS...THOUGH WOULD LIKE TO SEE A LITTLE MORE IMPRESSIVE DOWNDRAFT CAPE. 700 MB THETA/E AXIS WILL EXTEND FROM GOODLAND TO HASTINGS THIS EVENING...SO A FEW STORMS MAY PRODUCE BRIEF HEAVY RAIN. COLD FRONT AND DRIER AIR WILL MOVE ACROSS THE AREA AFTER 06Z. 1000/500 MB THICKNESS VALUES DROP...BUT NOT IMPRESSIVELY. WILL ONLY COOL TEMPERATURES SEVERAL DEGREES TONIGHT AND SUNDAY. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 333 AM MDT SAT AUG 11 2012 A LEE SURFACE TROUGH WILL BEGIN TO DEEPEN AHEAD OF A SHORTWAVE TROUGH OVER ALBERTA CANADA BY EARLY NEXT WEEK. AS A MINOR DISTURBANCE MOVES ACROSS THE LOCAL REGION...THERE IS A CHANCE FOR SOME SCATTERED CONVECTION TO OCCUR ALONG THE TROUGH AXIS AND MOVE EASTWARD WITH THE SHORTWAVE. THE CHANCE FOR CONVECTION WILL CONTINUE WED AS THE DOMINATING RIDGE OVER THE GREAT BASIN REGION CONTINUES TO WEAKEN AS THE VIGOROUS UPPER LEVEL SHORTWAVE TROUGH MOVES DOWN THROUGH CANADA AND INTO THE MIDWEST. THIS WILL ALLOW THE ASSOCIATED COLD FRONT TO BE PUSHED ACROSS THE HIGH AND CENTRAL PLAINS BY EARLY WED MORNING. COOLER TEMPERATURES WILL FOLLOW THE FRONTAL PASSAGE AND WILL COOL EVEN FURTHER BY THURSDAY AFTERNOON AS ANOTHER COLD FRONT MAKES ITS WAY ACROSS THE CENTRAL PLAINS. PRECIPITATION CHANCES LOOK TO INCREASE WITH THIS SECOND FRONTAL PASSAGE BEFORE DECREASING BY LATE NEXT WEEK WHEN THE SURFACE HIGH PRESSURE MOVES IN AND RIDGE BEGINS TO REBUILD OVER THE WESTERN PORTION OF THE COUNTRY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1040 AM MDT SAT AUG 11 2012 CONVECTION WILL DEVELOP OVER EASTERN COLORADO AROUND 21Z...AND THEN MOVE EAST. BASED ON SHORT RANGE MODELS...THUNDERSTORMS WILL LIKELY MOVE ACROSS KGLD BETWEEN 23Z-01Z. CONFIDENCE IS NOT AS HIGH AT KMCK...SO INDICATED THUNDERSTORMS IN VICINITY OF THAT LOCATION BETWEEN 01Z-03Z. SOUTH SURFACE WINDS 15-25 KNOTS WILL SWITCH TO THE NORTHWEST BEHIND A WEAK COLD FRONT AFTER 00Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...MENTZER LONG TERM...PMM AVIATION...MENTZER
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
412 PM EDT SAT AUG 11 2012 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 407 PM EDT SAT AUG 11 2012 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL LOW OVER SRN ONTARIO...JUST WEST OF TORONTO...SLOWLY LIFTING TO THE NORTHEAST. UPSTREAM...A SHORTWAVE TROUGH WAS LOCATED OVER SE MT LEAVING WEAK RIDGING FROM MN INTO WRN LAKE SUPERIOR. AT THE SFC...A RIDGE EXTENDED FROM JAMES BAY THROUGH NE MN INTO IA AHEAD OF A TROUGH OVER THE WRN PLAINS. TONIGHT...AS HIGH PRES BUILDS INTO THE REGION AND DAYTIME HEATING FADES...ANY REMAINING CU WILL DIMINISH THIS EVENING. THE AIRMASS WILL ALSO BE RELATIVELY DRY WITH PWAT VALUES AOB 0.50 INCH. WITH FAVORABLE RADIATIONAL COOLING CONDITIONS TONIGHT...LOW TEMPS WILL DROP TO THE LOWER 40S OVER THE INTERIOR W...WITH LOWS AROUND 50 OVER THE INTERIOR E. NEAR THE GREAT LAKES SHORES...LOWS WILL BE IN THE 50S TO NEAR 60. CANNOT RULE OUT SOME GROUND FOG AGAIN OVER THE WEST BUT SHOULD BE PATCHY/ISOLATED. SUNDAY...THE MODELS WERE CONSISTENT IN KEEPING THE PLAINS SHORTWAVE FAR ENOUGH TO THE SOUTHWEST OF THE CWA TO KEEP UPPER MI DRY. EVEN THOUGH THERE WILL BE INCREASING OVER THE WEST HALF DURING THE AFTERNOON ON THE NRN FRINGE OF THE SHRTWV FORCING...A DECENT AMOUNT OF SUNSHINE ALONG WITH WEAK WA WILL HELP PUSH TEMPS BACK INTO THE MID TO UPPER 70S. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 407 PM EDT SAT AUG 11 2012 UPPER MS VALLEY UPPER TROUGH WILL CROSS THE UPPER GREAT LAKES SUNDAY NIGHT INTO MONDAY. MOISTURE WILL BE LIMITED AND BEST FORCING WILL BE WELL SOUTH OF THE AREA CLOSER TO THE SURFACE LOW TRACKING ACROSS NORTHERN IL INTO LOWER MI. WILL KEEP LOW CHANCE POPS ACROSS THE AREA LATE SUNDAY NIGHT THROUGH MONDAY. LAKE BREEZES COULD BE THE FOCUS FOR SOME ADDED SHRA AND ISOLATED TSRA DEVELOPMENT MONDAY AFTERNOON. SURFACE LOW WILL CONTINUE EAST INTO SOUTHERN ONTARIO ON TUESDAY WITH HIGH PRESSURE BUILDING INTO WEST AND CENTRAL UPPER MI. RIDGE AXIS WILL PASS OVER THE AREA EARLY WEDNESDAY WITH WINDS TURNING TO THE SOUTHWEST DURING THE AFTERNOON. WITH PLENTY OF SUNSHINE THIS SHOULD BE THE WARMEST DAY OF THE WEEK WITH TEMPS NEAR 80 IN MANY AREAS. NEXT UPPER TROUGH AND COLD FRONT WILL BEGIN TO APPROACH THE AREA FROM THE WEST BY LATE IN THE DAY INTO WEDNESDAY NIGHT. THIS SHOULD OFFER UP A DECENT CHANCE OF RAIN ACROSS MUCH OF THE AREA AHEAD OF THE FRONT. SEVERE WEATHER CHANCES APPEAR TO BE MINIMAL BUT EXPECT AT LEAST A BROKEN BAND OF SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF THE FRONT FROM WEDNESDAY NIGHT INTO THURSDAY. AFTER THE FRONT PASSES AND WINDS TURN NORTHWESTERLY...DECENT COLD ADVECTION WILL LOWER 85H TEMPS INTO THE 2-4C RANGE. THUS...EXPECT SOME EARLY FALL LIKE CONDITIONS WITH POST FRONTAL LAKE EFFECT CLOUDS AND EVEN SOME LAKE INDUCED SHRAS FROM LATE THURSDAY INTO FRIDAY. SURFACE RIDGE AXIS WILL PASS OVER THE AREA ON SATURDAY WITH A MODERATING TREND BEGINNING THEREAFTER. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 134 PM EDT SAT AUG 11 2012 UNDER DRY AIR MASS ASSOCIATED WITH HIGH PRES DRIFTING INTO THE UPPER LAKES...EXPECT PREDOMINANT VFR CONDITIONS THROUGH THE FCST PERIOD AT ALL TAF SITES. THERE MAY BE SOME GROUND FOG AT KIWD...SIMILAR TO LAST NIGHT...BUT SHOULD BE BRIEF/INTERMITTENT. CONFIDENCE IS ALSO LIMITED THAT ANY WILL OCCUR SO WAS NOT INCLUDED AT THIS TIME. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 407 PM EDT SAT AUG 11 2012 AS HIGH PRESSURE BUILDS INTO THE REGION...WINDS WILL SLOWLY DIMINISH THROUGH TONIGHT. WINDS SUN THRU WED WILL BE MOSTLY 15KT OR LESS AS ONLY WEAK SYSTEMS AFFECT THE AREA. A FALL-LIKE LOW PRESSURE SYSTEM AND FRONT MOVING THROUGH LAKE SUPERIOR THURSDAY COULD PRODUCE STRONGER NW WINDS INTO THE 20-30 KT RANGE FROM THURSDAY INTO FRIDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...MZ AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
340 PM EDT SAT AUG 11 2012 .SHORT TERM...THIS EVENING AND TONIGHT THE CLOSED CIRCULATION OF THE BAROTROPIC UPPER LEVEL PRESSURE SYSTEM REMAINS CENTERED OVER PORTIONS OF FAR SOUTHWESTERN ONTARIO THIS AFTERNOON. THIS POSITIONING FOR THE PAST 6HRS SEEMS TO HAVE BEEN A RESULT OF A LAKE AGGREGATE EFFECT OFF OF THE CENTROID OF THE CENTRAL GREAT LAKES. THE EFFECTIVE REACH OF THE LOW HAS BEEN GREAT ENOUGH TO KEEP THE ENTIRETY OF EASTERN LOWER MICHIGAN UNDER A VEIL OF LOW TO MIDLEVEL STRATUS. EROSION OF THE WESTERN EDGE OF THE CLOUDS IS TAKING PLACE AS WE/RE CURRENTLY SEEING SOME CELLULAR BASED CLOUD SCALE CIRCULATIONS/SUBSIDENCE BRINGING SOME INCREASED SUNSHINE AT THE WESTERN CWA DOORSTEP. EVEN IF THIS OCCURS...TIME IS RUNNING OUT TO SALVAGE MUCH IF ANY OF THE TODAY PERIOD. MAY SEE A 3-5 DEGREE SPIKE IF THAT OCCURS...MERELY PUTTING US AT THE FORECASTED HIGH VALUES FOR TODAY. SUBTLE TROUGH AXIS WILL PUSH TO THE LAKE ERIE APPENDAGE PRIOR TO 00Z. THIS WILL OFFER ADDITIONAL SUPPORT FOR A CONTINUATION OF THE GRADIENT FLOW RIGHT UP TO THE ADVENT OF THE EVENING ALONG WITH THE SUBSEQUENT EVAPORATION/DRYING OF THE LOW LEVEL TROPOSPHERE. SOUTHEASTERN MICHIGAN WILL RESIDE IN A GENERAL AREA OF DIFFERENTIAL AVA THROUGH THE EVENING HOURS PER RAP-FORMERLY RUC. THIS RAP DATASET ALSO SEEMS TO HAVE A REASONABLE HANDLE OF THE CYCLONIC VORTICITY FILAMENT NOW EXITING THE FAR EAST. THUS...FOR THE REMAINDER OF THE AFTERNOON/EARLY EVENING WILL BE LOOKING AT POTENTIAL FOR SMALLISH WAVES OF LIGHT SHOWERS/DRIZZLE BUT NOT ANTICIPATING MUCH IN THE WAY OF WIDESPREAD HEAVY PRECIPITATION. LOSS OF INSOLATION THIS EVENING SHOULD SHUT EVERYTHING DOWN WITH TIME. ELEVATED LEVELS OF NEAR SURFACE MOISTURE BRINGS PROSPECTS OF FOG TOWARDS MORNING ESPECIALLY IF CLOUD COVER TOTALLY DISSIPATES. NOT SEEING A GREAT MODELED MOISTURE PROFILE FOR FOG TONIGHT AND WILL LEAVE PATCHY MENTION IN THE GRIDS...BEST POTENTIAL SHOULD BE IN LOW LYING AREAS. LACK OF ADVECTION WILL LIKELY KEEP LOWS IN THE MIDDLE TO UPPER 50S. && .LONG TERM...SUNDAY THROUGH SATURDAY ACTIVE WEATHER PATTERN WILL CONTINUE DURING THE UPCOMING WEEK WITH TWO MAJOR SYSTEM SLATED TO TRAVEL THROUGH THE GREAT LAKES...BOTH BRINGING THE CHANCE OF WIDESPREAD RAINFALL. THESE SYSTEMS WILL BE TRACKING INTO THE AREA WITHIN MEAN NORTHWEST UPPER FLOW...WITH THIS PATTERN ESSENTIALLY KEEPING TEMPERATURES NEAR AVERAGE FOR WARMEST DAYS IMMEDIATELY PRECEDING THESE STORM SYSTEMS AS SHORTWAVE RIDGING TRANSLATES THROUGH THE AREA TO BELOW AVERAGE AFTER IN THE WAKE OF THESE SYSTEMS AS COLD AIR ADVECTION AND RESIDUAL MOISTURE AND CLOUD COVER HOLDS TEMPERATURES DOWN. THE COOLEST AIRMASS WILL HOLD OFF UNTIL LATE IN THE FORECAST PERIOD AS SECOND SHORTWAVE TAPS A FAIR AMOUNT OF FALL-LIKE AIR AS IT DROPS ACROSS CANADA INTO THE LAKES REGION. THE FIRST SHORTWAVE IS EVIDENT ON WATER VAPOR IMAGERY CHURNING EAST ACROSS THE US ROCKIES NEAR THE MONTANA AND WYOMING STATE LINE. ITS COUNTERPART IS ANOTHER SHORTWAVE WHICH IS TRACKING OVER THE CANADIAN ROCKIES. BOTH VORTICITY CENTERS ARE QUITE WELL DEVELOPED ALREADY. THE POSITIONING OF THE SOUTHERN SHORTWAVE WILL FAVOR AN EVENTUAL TRACK OF THE MAIN ENERGY ACROSS THE NORTHERN OHIO VALLEY/SOUTHERN GREAT LAKES...WHICH WILL BE FAVORABLE FOR A FAIRLY WIDESPREAD AND STEADY RAIN ACROSS THE AREA. MODELS HAVE REMAINED RATHER CONSISTENT RUN TO RUN AS WELL AS IN RESPECT TO EACH OTHER IN BRINGING THIS STORM SYSTEM INTO THE AREA LATE MONDAY...HAVING THE BULK OF THE RESULTING PRECIPITATION EVENT OCCUR MONDAY NIGHT...AND THEN HOLDING ONTO LINGERING SHOWERS INTO TUESDAY. WILL NOT ADJUST FORECAST MUCH OTHER THAN TO INCREASE PRECIPITATION CHANCES SLIGHTLY AS CONFIDENCE IN THIS SCENARIO CONTINUES TO INCREASE. THE SECOND SYSTEM...STILL WELL OFF THE CANADIAN WEST COAST...WILL EVENTUALLY COME ONSHORE OVER BRITISH COLUMBIA AND TAP A LARGER CHUNK OF COLDER AIR AS THE NORTHERN STREAM COMPONENT OF THE JET ENERGY REMAINS DOMINANT AS IT CROSS NOAM. THIS WILL RESULT IN A SURFACE LOW TRACKING THROUGH SOUTHERN CANADA AND JUST BRUSHING THE NORTHERN GREAT LAKES. THIS LOW WILL FORCE A STRONG COLD FRONT THROUGH THE GREAT LAKES AS IT WRAPS UP INTO THE JAMES BAY/HUDSON BAY AREA. THE TIMING IS SLIGHTLY MORE ELUSIVE...BUT FOR A DAY 6/7 FORECAST...THE CONFIDENCE REMAINS HIGHER THAN NORMAL AS MODELS SUGGEST A THURSDAY NIGHT INTO FRIDAY TIME FRAME. THIS SCENARIO...WITH THE MAIN SYSTEM NORTH OF THE REGION...SUPPORTS A LINE OR LINES OF CONVECTION IN ADVANCE OR WITH THE COLD FRONTAL PASSAGE...FOLLOWED BY WRAPAROUND MOISTURE AND EVEN SOME LAKE EFFECT/ENHANCED SHOWER ACTIVITY HEADING INTO THE WEEKEND AS THE COOLER AIR INTERACTS WITH RELATIVELY WARM LAKE WATERS. SO...OVERALL...WHILE RAIN CHANCES LOOK PRETTY GOOD AT THIS POINT...THIS ACTIVITY WILL BE SHORTER LIVED AND MORE SCATTERED IN NATURE THAN THE SYSTEM EARLY IN THE WEEK. AS ELUDED TO EARLIER...TEMPERATURES WILL OSCILLATE BETWEEN AVERAGE AND BELOW AVERAGE WITH THE APPROACH AND THEN DEPARTURE OF THESE STORM SYSTEMS. THIS WILL BRING HIGH TEMPERATURES AROUND 80 EARLY IN THE WEEK AND AGAIN WEDNESDAY/THURSDAY...WITH HIGHS CLOSER TO 70 TUESDAY AND 70 OR LESS FRIDAY INTO SATURDAY. LOWS WILL RANGE IN THE UPPER 50S TO LOWER 60S UNTIL THE LAST PART OF THE FORECAST PERIOD WHEN LOWS AROUND 50 WILL BE MORE COMMON AS THE COLDER AIRMASS SPILLS INTO THE AREA. IN FACT...A FEW READINGS IN THE 40S SEEM PROBABLE BY NEXT WEEKEND IF THE CURRENT BASIC STORM TRACK SCENARIO HOLDS CLOSE TO CURRENT PROJECTIONS. && .MARINE... THE BROAD LOW PRESSURE CENTER CIRCULATION IS IN PLACE OVER FAR SOUTHERN LAKE HURON THIS AFTERNOON. OVERALL...THE WEAK SFC LOW FEATURE HAS KEPT CONDITIONS RELATIVELY IN CHECK GIVEN THE ANOMALOUS PARENT UPPER LEVEL SYSTEM. THE AREA WATERS ARE EXPERIENCE SOME LOW STABILITY CONDITIONS WHICH WILL MAINTAIN THE RESIDUAL CHOPPY SEA STATE THROUGH THE TONIGHT PERIOD. THIS IS HANDLED IN THE NEARSHORE ZONES WITH SMALL CRAFT ADVISORIES THAT ARE IN EFFECT UNTIL 2Z THIS EVENING. WAVE HEIGHTS SHOULD TRANSLATE QUICKLY AWAY FROM THE US WATERS OVERNIGHT...AND THE DECISION WAS MADE TO MAINTAIN THE INHERITED TIMING OF HEADLINES. BUILDING HIGH PRESSURE WILL BRING MUCH CALMER CONDITIONS LATE SUNDAY AND SUNDAY NIGHT. AN APPROACHING TROUGH OF LOW PRESSURE WILL ADVANCE INTO THE GREAT LAKES REGION BY MONDAY NIGHT...POTENTIALLY SUPPORTING A SURFACE LOW CENTER THAT WOULD TRACK THROUGH SOUTHEASTERN MICHIGAN ON TUESDAY. AVAILABLE MODEL GUIDANCE IS NOT VERY STRONG WITH THE LAKE EFFECT POTENTIAL OF SHOWERS AND TSTORMS OVERNIGHT. WITH THAT SAID...PATTERN RECOGNITION SUGGESTS CONVECTION WILL BE POSSIBLE THROUGHOUT THE NIGHT. GIVEN THE STABILITY AND VORTICITY RICH ENVIRONMENT....WATERSPOUTS WILL BE POSSIBLE WITH ANY ACTIVITY. && .AVIATION...ISSUED 128 PM EDT SAT AUG 11 2012 //DISCUSSION... A MOIST/SATURATED ENVIRONMENT REMAINS IN PLACE ACROSS ALL OF SOUTHEASTERN MICHIGAN AS THE BAROTROPIC LOW STRUCTURE IS NOW CENTERED DIRECTLY EAST OF THE FORECAST AREA. HAVE BEEN WITNESSING ON MSLP SFC ANALYSIS AND SATELLITE IMAGERY SIGNS THE LOW IS FAVORING THE CENTRAL GREAT LAKES REGION AS AN AGGREGATE EFFECT. SOUTHEASTERN MICHIGAN RESIDES ON THE WESTERN PERIPHERY IN NORTHERLY FLOW SECTOR...WHICH MEANS PERIODS OF LIGHT SHOWERS AS WAVES OF WRAP AROUND MOISTURE WORK THROUGH. THE ONLY REAL ISSUE TO WATCH FOR IS ANY HEAVIER SHOWER/ISOLATED TSTORM DEVELOPMENT WITH ANY BREAKS IN THE CLOUDS AND BRIEF SHOT OF INSOLATION. CONFIDENCE IN THIS OCCURRING REMAINS LOW. LOSS OF INSOLATION THIS EVENING...COMBINED WITH RISING HEIGHTS SHOULD YIELD TO BUILDING SURFACE HIGH PRESSURE AND A DISSIPATION IN MVFR/VFR TYPE CLOUDS.THE TIMING CONFIDENCE ON THIS REMAINS SHAKY GIVEN PATTERN RECOGNITION. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE CEILINGS WILL REMAIN BELOW 5000 FT THROUGH THE AFTERNOON. * VERY LOW CONFIDENCE WITH A THUNDERSTORM AFFECTING DTW TODAY. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...INNER SAGINAW BAY...UNTIL 4 PM SATURDAY. SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS FROM PORT AUSTIN TO PORT SANILAC...UNTIL 10 PM SATURDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...CB LONG TERM....DG MARINE.......CB AVIATION.....CB YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
132 PM CDT SAT AUG 11 2012 .DISCUSSION... OVERVIEW...ONLY SIGNIFICANT FORECAST CHALLENGE IN THE COMING DAYS LIES WITH THE SYSTEM CURRENTLY MOVING INTO THE DAKOTAS...WHICH WILL AFFECT THE SENSIBLE WEATHER IN MINNESOTA AND PERHAPS EVEN FAR WESTERN WI OVER THE NEXT 30 HOURS. COOL AND RAINY WEATHER IS ALMOST GUARANTEED FROM WEST CENTRAL TO SOUTH CENTRAL MINNESOTA ON SUNDAY. CONTINUED NORTHWEST FLOW AND COOLER THAN NORMAL TEMPERATURES WILL BE AT WORK ALL THE WAY THROUGH THE EXTENDED. AFTER SUNDAY...NEXT CHANCE FOR RAIN DOES NOT ARRIVE UNTIL MID WEEK WHEN A SURFACE TROUGH AND COLD FRONT PASS THROUGH THE AREA. IF ALL GOES WELL TODAY...WE WILL HAVE OUR RADAR BACK BY THIS EVENING AND WE CAN ALL WATCH TOGETHER AS THE RAIN SHIELD ADVANCES INTO MINNESOTA FROM THE DAKOTAS. PROBABLY A LITTLE BIT HIGHER CONFIDENCE WITH THE FORECAST DONE TODAY GIVEN THE TIGHTER CLUSTERING OF MODEL SOLUTIONS COMPARED TO THE LAST COUPLE DAYS. MOST NOTABLE CHANGE PROBABLY COMES WITH THE NORTHERN JUMP OF THE SURFACE REFLECTION IN THE 11.12Z NAM. THE EC HAS BEEN ON THE NORTHERN SIDE OF THE MODEL SPREAD...GFS - VERY CONSISTENTLY SOMEWHERE IN THE MIDDLE...AND THE NAM HAS BEEN PRETTY FAR SOUTH. SO...WITH THE NORTHERN JUMP ON THE NAM...THERE IS HIGHER CONFIDENCE IN WESTERN AND SOUTHERN MN GETTING A SOLID 6-12 HOURS OF DEFORMATION BANDED RAINFALL. CURRENT WATER VAPOR IMAGERY AND 500MB RUC ANALYSIS SUGGEST THE UPPER WAVE NOW COMING OUT OF THE NORTHERN ROCKIES IS NOT BEING COMPLETELY MISHANDLED BY EITHER THE NAM/GFS/EC. HOWEVER...WOULD HAVE TO SAY THAT THE 11.12Z NAM/UKMET ARE PROBABLY JUST A TOUCH BETTER THAN THE EC/GFS...WHICH HAVE THE GREATEST HEIGHT FALLS AND LOW CENTER JUST A BIT TOO FAR TO THE NORTHEAST AT 18Z TODAY. AT ANY RATE...INCREASED POPS TO 90-100% IN WEST CENTRAL AND SOUTH CENTRAL MN...AS IT IS HARD TO IMAGINE A SITUATION WHERE MEASURABLE RAIN BY PASSES THESE AREAS. THE 700MB LOW TRACK AND 850-700MB FGEN...WHICH IS QUITE GOOD...ARE BOTH FAVORABLE FOR A WIDESPREAD 0.25" OR MORE IN THESE AREAS. THERE IS NOT GREAT CONVECTIVE POTENTIAL...SO DON`T THINK WE WILL SEE MANY LOCATIONS GET NEAR 1"...BUT THERE SHOULD BE A LOT OF 0.50" TOTALS IN AREAS THAT SORELY NEED THE RAIN. STILL MEAGER MUCAPE SHOWING UP AND IT IS AUGUST SO STILL INCLUDED SLIGHT CHANCE OF THUNDER IN THE FORECAST. MUCH BIGGER QUESTION MARK FOR AREAS IN EAST CENTRAL MN AND WESTERN WI. ALTHOUGH THIS SYSTEM HAS TRENDED A BIT STRONGER AND FARTHER NORTH...LOCATIONS ON THE NORTH SIDE OF THE BEST BANDED PRECIP MAY ONLY END UP WITH A TENTH OR A FEW HUNDREDTH. THIS INCLUDES THE TWIN CITIES METRO. THE 11.12Z GFS HAS A QPF BULLSEYE MUCH FURTHER NORTH THAN MOST OF THE OTHER GUIDANCE...BUT GET THE FEELING THIS IS A BIT AGGRESSIVE AND THAT THE LOCATION OF THE LOW LEVEL FGEN AND QG FORCING A BIT FURTHER SOUTH WILL ANCHOR THE RAIN MORE IN WESTERN AND SOUTHERN MN. STILL INCREASED POPS FOR THE LIKELIHOOD OF AT LEAST A FEW HUNDREDTHS IN MANY AREAS TOMORROW. AS MENTIONED PREVIOUSLY...WE WILL SEE BRIEF RIDGING FOR TUESDAY AS THE NEXT STRONG TROUGH MOVES INTO THE REGION FOR WEDNESDAY AFTERNOON/WEDNESDAY NIGHT. THERE IS MUCH BETTER CONVECTIVE POTENTIAL WITH THIS SYSTEM. SHOULD SEE MUCH COOLER CONDITIONS FOLLOWING THIS TROUGH INTO THE WEEKEND. && .AVIATION.../18Z TAF ISSUANCE/ HIGH PRESSURE CENTERED OVER EASTERN MINNESOTA WILL SLIDE OFF TO THE SOUTHEAST TODAY AS A LOW PRESSURE SYSTEM CURRENTLY LOCATED IN WESTERN NEBRASKA MOVES EAST. HIGH CLOUDS MOVED INTO WESTERN MINNESOTA THIS MORNING AND WILL ADVANCE TO EASTERN MINNESOTA BY EVENING. THE LOW PRESSURE AREA WILL MOVE TO SOUTHWEST MINNESOTA BY SUNRISE SUNDAY PROVIDING AN OPPORTUNITY FOR LOWER CEILINGS AND RAIN. THE GFS MODEL WOULD LIKE TO EXTEND A LARGER PRECIPITATION SHIELD THAN THE NAM...AM LEANING WITH THE NAM. CEILINGS IN THE DAKOTAS HAVE BEEN ABOVE 060 FOR THE MOST PART. THE BEST CHANCES FOR RAIN WILL BE SOUTH OF A KAXN TO KMSP LINE. SOUTH OF THIS LINE RAIN CAN BE EXPECTED FROM EARLY MORNING THROUGH THE AFTERNOON. CEILINGS MAY BECOME MVFR AT KRWF. OTHERWISE DO NOT EXPECT ANYTHING LESS THAN VFR ELSEWHERE AT THIS POINT IN TIME. THE PRECIPITATION GRADIENT MAY BE RATHER SHARP...IN FACT KMSP/KSTC/ KAXN MAY SEE MORE SPRINKLES IN THE MORNING TO EARLY AFTERNOON THAN STEADY RAIN. WILL HAVE TO MONITOR THIS CLOSELY. MSP...VFR THROUGH THE PERIOD. HIGH CLOUDS WILL THICKEN AND LOWER TONIGHT THROUGH SUNDAY MORNING. GFS WOULD LIKE TO START PRECIPITATION AROUND SUNRISE. NAM IS SLOWER AND MORE COMPACT IN TERMS OF THE AREAL EXTENT WITH PRECIPITATION BEGINNING AT 16Z. ELECTED TO BEGIN PRECIPITATION AT 18Z DUE TO THE VERY DRY AIRMASS CURRENTLY IN PLACE AND BELIEF THAT IT MAY TAKE LONGER TO SATURATE TO THE POINT OF PRECIPITATION. THERE WILL BE A SHARP INCREASE IN PRECIPITATION CHANCES TO THE SOUTH AND A SHARP DECREASE TO THE NORTH. WINDS 7 KT OR LESS THROUGHOUT THE PERIOD...MAINLY FROM THE SOUTHEAST. OUTLOOK... SUNDAY NIGHT...VFR-MVFR WITH SHRA AND ISOLD TSRA POSSIBLE...AT KRWF. SE WINDS 5-10 KTS. MONDAY...VFR. NW WINDS 5-10 KTS. TUESDAY...VFR. VARIABLE WINDS 5 KTS. WEDNESDAY...VFR...ISOLD TSRA IN THE AFTERNOON. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ CLF/DRL
AREA FORECAST DISCUSSION
NWS HASTINGS NE
408 PM CDT SAT AUG 11 2012 .SHORT TERM...THROUGH 00Z MONDAY. MORNING UPPER AIR ANALYSIS INDICATES UPPER LEVEL RIDGING OVER THE SOUTHWESTERN CONUS AND TROUGHING OVER THE EASTERN CONUS. A MID LEVEL SHORT WAVE IS ALSO NOTED OVER EASTERN MONTANA. MID AND UPPER LEVEL JET ENERGY IS SITUATED FROM THE NORTHWESTERN CONUS...EASTWARD INTO THE NORTHERN PLAINS...AND THEN SOUTHEAST ACROSS THE MISSOURI AND MISSISSIPPI VALLEYS ON INTO THE SOUTHEASTERN CONUS. THIS ~70KT UPPER LEVEL JET AXIS REMAINS JUST TO THE EAST OF OUR CWA...MORE OVER EASTERN NEBRASKA AND IOWA...THUS RESULTING IN FAIRLY WEAK TROPOSPHERIC FLOW OVER SOUTH CENTRAL NEBRASKA AND NORTH CENTRAL KANSAS. WATER VAPOR IMAGERY DOES NOT INDICATE A SUFFICIENT TROPICAL TAP OF MID LEVEL MOISTURE ACROSS THE CENTRAL CONUS TODAY...BUT INCREASING MID LEVEL MOISTURE IS NOTED OVER THE NORTHERN ROCKY MOUNTAIN RANGE AND PORTIONS OF THE NORTHERN AND CENTRAL PLAINS AS THE MID LEVEL SHORT WAVE...CURRENTLY OVER EASTERN MONTANA...APPROACHES FROM THE NORTHWEST. THERE ALSO APPEARS TO BE A SUBTLE MID LEVEL PERTURBATION WORKING ACROSS NEBRASKA AT THIS TIME AS WELL. AT THE SURFACE A RIDGE OF HIGH PRESSURE IS NOTED OVER THE UPPER MISSISSIPPI VALLEY...WITH LOW LEVEL RETURN FLOW ON THE BACK SIDE OF THE RIDGE AXIS OVERTAKING MUCH OF THE CENTRAL PLAINS. A SURFACE LOW IS ALSO NOTED OVER WESTERN NORTH DAKOTA...WITH AN ASSOCIATED COLD FRONT EXTENDING SOUTH FROM THE LOW ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS. WEAK FORCING AHEAD OF THE SUBTLE MID LEVEL PERTURBATION NOW PUSHING ACROSS NEBRASKA IS HELPING PROMOTE ELEVATED PRECIPITATION PRODUCTION ACROSS PORTIONS OF CENTRAL NEBRASKA...WITH RADAR DATA FROM KUEX INDICATING ISOLATED TO SCATTERED RETURNS ACROSS NORTHERN PORTIONS OF OUR CWA AS OF 20Z. THAT BEING SAID...PRECIPITATION REPORTS HAVE BEEN HARD TO COME BY WITH THIS ACTIVITY WITH PROXIMITY SOUNDINGS ACROSS OUR CWA PER RAP ANALYSIS INDICATING PLENTY OF LOW LEVEL DRY AIR IN PLACE. STILL...QPF FIELDS FROM THE 11/12Z NAM AND OPERATIONAL GFS...AS WELL AS THE 11/12Z EC AND 11/09Z SREF-MEAN...ALL SUGGEST AT LEAST SOME PRECIPITATION WILL BE REALIZED AT THE SURFACE ACROSS PORTIONS OF OUR WESTERN AND NORTHERN CWA THROUGH 00Z THIS EVENING. GIVEN THE CURRENT RETURNS FROM AREA RADARS...AS WELL AS THE ABOVE-MENTIONED MODEL OUTPUT...WENT AHEAD AND INSERTED 20% POPS ACROSS THE NORTHERN TWO- THIRDS OF OUR CWA THROUGH THIS EVENING. AS MENTIONED EARLIER...LOW LEVEL MOISTURE VALUES ARE FAIRLY LOW AS OF EARLY AFTERNOON WITH SURFACE DEW POINTS ACROSS OUR CWA GENERALLY IN THE 50S. THIS IS HELPING KEEP INSTABILITY ON THE WEAK SIDE ACROSS SOUTH CENTRAL NEBRASKA AND NORTH CENTRAL KANSAS. THAT BEING SAID...THE NAM DOES INDICATE 0-1KM MLCAPE VALUES WILL INCREASE TO ~500J/KG ACROSS OUR NORTHERN CWA LATER THIS AFTERNOON AS MID LEVEL LAPSE RATES UNDERNEATH THE MID LEVEL PERTURBATION INCREASE. CHANCES FOR SEVERE WEATHER THIS AFTERNOON AND EVENING APPEAR VERY LOW DUE TO THE OVERALL LACK IN INSTABILITY...BUT THE RAP ANALYSIS PROXIMITY SOUNDINGS ALSO INDICATE VERY DEEP INVERTED-V SOUNDINGS ACROSS MUCH OF THE CWA WHICH WILL BE CONDUCIVE FOR BRIEF DOWN BURSTS DESPITE THE GENERALLY WEAK CONVECTION. GIVEN ALL THIS...WILL ALSO GO AHEAD AND INTRODUCE STRONG STORM WORDING...BRIEF WIND GUSTS TO AROUND 50 MPH...TO THE HWO FOR THIS AFTERNOON AND EVENING...AGAIN PRIMARILY FOR LOCATIONS ACROSS OUR NORTHERN CWA. SHOWERS WITH EMBEDDED THUNDERSTORMS SHOULD INCREASE IN AERIAL COVERAGE ACROSS OUR CWA AS THE MAIN MID LEVEL SHORT WAVE APPROACHES FROM EASTERN MONTANA. PLENTY OF DPVA AND MID LEVEL THERMAL ADVECTION AHEAD OF THE MID LEVEL TROUGH AXIS SHOULD PRESENT A DECENT PRECIPITATION SHIELD SOMEWHERE OVER THE REGION...WITH QPF FIELDS FROM THE 11/12Z NAM...OPERATIONAL GFS...EC...AS WELL AS THE 11/09Z SREF-MEAN...11/12Z 4KM WRF- NMM...AND 11/16Z HRRR ALL SUGGESTING THE MOST LIKELY AREA OF MEASURABLE PRECIPITATION IS LOCATED FROM NORTH CENTRAL NEBRASKA INTO EASTERN NEBRASKA...WITH THESE BEST CHANCES FOR PRECIPITATION CLIPPING OUR NORTHEASTERN CWA...ALTHOUGH ITS IMPORTANT TO REMEMBER PRECIPITATION CHANCES ARE IN THE FORECAST FOR THE ENTIRE CWA. THE NAM SUGGESTS OVERNIGHT DEEP LAYER MUCAPE VALUES OF AROUND 100J/KG WILL BE REALIZED ACROSS PORTIONS OF THE AREA TONIGHT...AND WITH THE AMOUNT OF DPVA AND MID LEVEL THERMAL ADVECTION INFILTRATING THE AREA TONIGHT...WOULD EXPECT MORE OF A STRATIFORM RAIN EVENT WITH EMBEDDED CONVECTIVE CLUSTERS WITHIN THE MAIN PRECIPITATION SHIELD. WENT AHEAD WITH ONLY AN ISOLATED THUNDER MENTION IN THE FORECAST FOR TONIGHT AS A RESULT...WITH NOTHING IN THE WAY OF SEVERE WEATHER CURRENTLY EXPECTED. PRECIPITATION SHOULD QUICKLY COME TO AN END SUNDAY MORNING AS THE MID LEVEL TROUGH AXIS CLEARS THE AREA BY 12Z SUNDAY AND SUBSIDENCE QUICKLY INFILTRATES THE AREA THROUGH THE REMAINDER OF SUNDAY. THE SURFACE LOW...CURRENTLY OVER WESTERN NORTH DAKOTA...IS EXPECTED TO MOVE SOUTHEAST ACROSS THE DAKOTAS AND INTO THE MISSOURI AND MISSISSIPPI VALLEYS OVERNIGHT TONIGHT INTO TOMORROW. THE ASSOCIATED COLD FRONT WILL ALSO MOVE SOUTHEAST AND IS EXPECTED TO PUSH ACROSS OUR CWA DURING THE DAY SUNDAY. THAT BEING SAID THERE ARE INDICATIONS...ESPECIALLY FROM THE NAM...THAT THE TRUE LOW LEVEL COLD AIR ADVECTION WILL LIKELY HOLD OFF UNTIL THE AFTERNOON AND EVENING HOURS ON SUNDAY BEFORE INFILTRATING OUR CWA. THIS SCENARIO LOOKS A LOT LIKE THIS PAST WEDNESDAY WHERE WE HAD A WIND SHIFT TO THE WEST/NORTHWEST AND THIS DOWN-SLOPING WIND...WHICH ALLOWED THE LOW LEVEL AIRMASS TO DRY OUT VERY QUICKLY BUT ALSO EFFICIENTLY HEAT UP AS THE COOLER AIR REMAINED WELL NORTH OF THE AREA...RESULTED IN A FORECAST WHICH PRESENTED AN OVERWHELMING COLD BIAS WITH MANY LOCATIONS COMING DANGEROUSLY CLOSE TO CRITICAL FIRE WEATHER CONDITIONS. GIVEN ALL THIS...OPTED TO PLAY CLOSE TO NAM/MET GUIDANCE...WHICH BOIVERIFY INDICATES PERFORMED THE BEST OF ANY MODEL HEADING INTO LAST WEDNESDAY...FOR SUNDAY TEMPERATURES...DEW POINTS AND WINDS. AS A RESULT...THE CURRENT FORECAST SHOWS AFTERNOON RELATIVE HUMIDITY VALUES IN THE 23%-25% RANGE ACROSS THE SOUTHWESTERN ONE-THIRD OF OUR CWA. BREEZY CONDITIONS WILL ALSO BE OBSERVED POST-FROPA ON SUNDAY BUT WITH THE COOLER AIR LAGGING WELL BEHIND...ACROSS THE NORTHERN PLAINS THROUGH MUCH OF THE DAY...THE STRONGEST LOW LEVEL PRESSURE GRADIENT AND RESULTANT STRONGEST WINDS SHOULD ALSO REMAIN RELEGATED TO NORTHERN PORTIONS OF THE CWA. ALTHOUGH SUSTAINED WINDS OF ~20KTS EXIST IN THE FORECAST FOR NORTHERN PORTIONS OF THE CWA...FARTHER SOUTH WHERE SURFACE RELATIVE HUMIDITY VALUES WILL BE LOWER...SUSTAINED WINDS ARE ONLY EXPECTED TO CLIMB INTO THE 14-16KT RANGE. SO...AT THIS TIME CRITICAL FIRE WEATHER CONDITIONS ARE NOT FORECAST FOR SUNDAY...BUT THIS IS SOMETHING FUTURE SHIFTS WILL CERTAINLY WANT TO MONITOR CLOSELY. WILL GO AHEAD AND HIGHLIGHT NEAR CRITICAL FIRE WEATHER CONDITIONS ACROSS OUR SOUTHWEST IN THE HWO TO GET THE WORD OUT. FINALLY...BOIVERIFY INDICATES BCCONSRAW HAS BEEN DOING VERY WELL WITH RESPECT TO SHORT TERM OVERNIGHT TEMPERATURE FORECASTS AND AS A RESULT...FOLLOWED CLOSELY TO BCCONSRAW FOR OVERNIGHT LOWS TONIGHT. .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY. OVERALL THIS WILL BE A COOL PERIOD WITH HIGH TEMPERATURES GENERALLY RUNNING BELOW NORMAL ON MOST DAYS. IN ADDITION...THERE WILL BE SEVERAL CHANCES OF SHOWERS AND THUNDERSTORMS. SUNDAY NIGHT THROUGH MONDAY. AN UPPER TROUGH WILL TRACK FROM IOWA INTO THE GREAT LAKES WITH COOL HIGH PRESSURE SETTLING INTO THE REGION. THIS WILL ALSO RESULT IN DRY WEATHER. MONDAY SHOULD BE A GREAT DAY AS THE WINDS BECOME LIGHT UNDER THE SFC HIGH PRESSURE AND HIGH TEMPERATURES WILL RANGE FROM AROUND 80 OVER SOUTHERN NEBRASKA TO THE MID 80S OVER NORTHERN KANSAS. DECIDED TO GO A TOUCH BELOW GUIDANCE WITH HIGH TEMPERATURES OVER NEBRASKA ZONES. MONDAY NIGHT THROUGH TUESDAY...A WEAK SHORT WAVE WILL TRACK THROUGH THE CENTRAL PLAINS. HOWEVER...FORECAST MODELS ARE NOT IN VERY GOOD AGREEMENT ON THE TRACK OF THIS SYSTEM. THE 12Z ECMWF WOULD MAKE FOR A RATHER RAINY MONDAY NIGHT INTO TUESDAY WHILE THE GFS IS LESS EXCITED ABOUT PRECIPITATION. TYPICALLY THIS HAS BEEN THE OTHER WAY AROUND THIS SEASON WITH THE GFS SHOWING MORE QPF. ULTIMATELY IT DEPENDS ON THE TRACK OF THE WAVE AND WILL CONTINUE TO CARRY SLIGHT POPS FOR NOW AND WILL WAIT FOR BETTER MODEL AGREEMENT BEFORE RAISING OR LOWING POPS DURING THIS PERIOD. THE TIMING OF THIS WAVE WOULD PUT THE MOST LIKELY TIMING OF POSSIBLE PRECIPITATION AFTER MIDNIGHT MONDAY NIGHT THROUGH THE FIRST HALF OF TUESDAY. WEDNESDAY AND THURSDAY...A STRONGER SHORT WAVE WITH A SHARP COLD FRONT WILL TRACK ACROSS OUR FORECAST AREA WEDNESDAY INTO WEDNESDAY EVENING. THIS WILL RESULT IN SCATTERED THUNDERSTORMS WITH A FEW POSSIBLY STRONG STORMS. THUNDERSTORMS WILL FOR THE MOST PART HAVE MOVED THROUGH BY THURSDAY MORNING...WITH A CHANCE OF POST FRONTAL RAIN SHOWERS DURING THE DAY ON THURSDAY. WEDNESDAY WILL LIKELY BE ONE OF THE HOTTER DAYS OF THE WEEK AND POSSIBLY THE ONLY DAY DURING THE LONG TERM PERIOD WITH ABOVE NORMAL HIGHS. HOWEVER...THE TIMING OF THE COLD FRONT MAY IMPACT HIGH TEMPERATURES ACROSS NORTHERN ZONES AND WILL NEED TO BE WATCHED CLOSELY. TEMPERATURES ON THURSDAY WILL ONLY BE IN THE 70S ACROSS NEBRASKA TO AROUND 80 OVER NORTHER KANSAS. THE NEW CONSALL TEMPERATURES ARE ACTUALLY EVEN A FEW DEGREES COOLER WITH THURSDAY HIGHS. FRIDAY AND SATURDAY...DRY WEATHER WILL RETURN WITH HIGH PRESSURE SETTLING IN BEHIND THE DEPARTING STORM SYSTEM. HIGH TEMPERATURES WILL SLOWLY WARM...BUT REMAIN COOLER THAN NORMAL. && .PREV DISCUSSION... /ISSUED 1226 PM CDT SAT AUG 11 2012/ AVIATION...18Z KGRI TAF. VFR CONDITIONS EXPECTED THROUGH THE NEXT 24 HOURS. MID LEVEL CLOUDS WILL PERSIST AT THE TERMINAL THROUGH MUCH OF THE TAF PERIOD...BUT NOTHING BELOW 8000FT AGL CURRENTLY EXPECTED. SHOWERS WITH EMBEDDED THUNDERSTORMS WILL BE OBSERVED ACROSS PORTIONS OF THE REGION TONIGHT AND AS A RESULT...WILL GO AHEAD WITH PROB30 TSRA 03Z-06Z...AND PREVAILING TSRA 06Z-09Z. THERE MAY BE SOME ISOLATED CONVECTION NEAR THE TERMINAL THIS AFTERNOON AND EVENING AS WELL...BUT AT THIS TIME THE PROBABILITY OF MEASURABLE PRECIPITATION BEING REALIZED AT KGRI THIS AFTERNOON AND EVENING IS FAR TOO LOW FOR INSERTION INTO THE TAF AT THIS TIME. PRECIPITATION SHOULD QUICKLY DEPART TO THE EAST OF THE TERMINAL BY 09Z SUNDAY WITH CLEARING SKIES OBSERVED SHORTLY THEREAFTER. MINOR VISIBILITY RESTRICTIONS TO AROUND 6SM WILL BE POSSIBLE IN PRECIPITATION 03Z-09Z. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM/AVIATION...BRYANT LONG TERM...WESELY
AREA FORECAST DISCUSSION
NWS HASTINGS NE
125 PM CDT SAT AUG 11 2012 .UPDATE...MORNING UPPER AIR ANALYSIS INDICATES UPPER LEVEL RIDGING OVER THE SOUTHWESTERN CONUS AND TROUGHING OVER THE EASTERN CONUS. A MID LEVEL SHORT WAVE IS ALSO NOTED OVER EASTERN MONTANA. MID AND UPPER LEVEL JET ENERGY IS SITUATED FROM THE NORTHWESTERN CONUS...EASTWARD INTO THE NORTHERN PLAINS...AND THEN SOUTHEAST ACROSS THE MISSOURI AND MISSISSIPPI VALLEYS ON INTO THE SOUTHEASTERN CONUS. THIS ~70KT UPPER LEVEL JET AXIS REMAINS JUST TO THE EAST OF OUR CWA...MORE OVER EASTERN NEBRASKA AND IOWA...THUS RESULTING IN FAIRLY WEAK TROPOSPHERIC FLOW OVER SOUTH CENTRAL NEBRASKA AND NORTH CENTRAL KANSAS. WATER VAPOR IMAGERY DOES NOT INDICATE A SUFFICIENT TROPICAL TAP OF MID LEVEL MOISTURE ACROSS THE CENTRAL CONUS TODAY...BUT INCREASING MID LEVEL MOISTURE IS NOTED OVER THE NORTHERN ROCKY MOUNTAIN RANGE AND PORTIONS OF THE NORTHERN AND CENTRAL PLAINS AS THE MID LEVEL SHORT WAVE...CURRENTLY OVER EASTERN MONTANA...APPROACHES FROM THE NORTHWEST. THERE ALSO APPEARS TO BE A SUBTLE MID LEVEL PERTURBATION WORKING ACROSS NEBRASKA AT THIS TIME AS WELL. AT THE SURFACE A RIDGE OF HIGH PRESSURE IS NOTED OVER THE UPPER MISSISSIPPI VALLEY...WITH LOW LEVEL RETURN FLOW ON THE BACK SIDE OF THE RIDGE AXIS OVERTAKING MUCH OF THE CENTRAL PLAINS. A SURFACE LOW IS ALSO NOTED OVER WESTERN NORTH DAKOTA...WITH AN ASSOCIATED COLD FRONT EXTENDING SOUTH FROM THE LOW ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS. WEAK FORCING AHEAD OF THE SUBTLE MID LEVEL PERTURBATION NOW PUSHING ACROSS NEBRASKA IS HELPING PROMOTE ELEVATED PRECIPITATION PRODUCTION ACROSS PORTIONS OF NEBRASKA...WITH RADAR DATA FROM KUEX AND KLNX INDICATING ISOLATED TO SCATTERED RETURNS ACROSS NORTHERN AND WESTERN NEBRASKA AS OF 18Z. THAT BEING SAID...PRECIPITATION REPORTS HAVE BEEN HARD TO COME BY WITH THIS ACTIVITY WITH PROXIMITY SOUNDINGS ACROSS OUR CWA PER RAP ANALYSIS INDICATING PLENTY OF LOW LEVEL DRY AIR IN PLACE. STILL...QPF FIELDS FROM THE 11/12Z NAM AND OPERATIONAL GFS...AS WELL AS THE 11/00Z EC AND 11/09Z SREF-MEAN...ALL SUGGEST AT LEAST SOME PRECIPITATION WILL BE REALIZED AT THE SURFACE ACROSS PORTIONS OF OUR WESTERN AND NORTHERN CWA THROUGH 00Z THIS EVENING. THIS SOLUTION IS ALSO SUPPORTED BY THE 11/00Z 4KM WRF-NMM. GIVEN THE CURRENT RETURNS FROM AREA RADARS...AS WELL AS THE ABOVE-MENTIONED MODEL OUTPUT...WENT AHEAD AND INSERTED 20% POPS ACROSS NORTH/NORTHWESTERN PORTIONS OF OUR CWA FOR THIS AFTERNOON AND EVENING. AS MENTIONED EARLIER...LOW LEVEL MOISTURE VALUES ARE FAIRLY LOW AS OF MIDDAY WITH SURFACE DEW POINTS ACROSS OUR CWA GENERALLY IN THE 50S. THIS IS HELPING KEEP INSTABILITY ON THE WEAK SIDE ACROSS SOUTH CENTRAL NEBRASKA AND NORTH CENTRAL KANSAS. THAT BEING SAID...THE NAM DOES INDICATE 0-1KM MLCAPE VALUES WILL INCREASE TO ~500J/KG ACROSS OUR NORTHERN CWA LATER THIS AFTERNOON AS MID LEVEL LAPSE RATES UNDERNEATH THE MID LEVEL PERTURBATION INCREASE. CHANCES FOR SEVERE WEATHER THIS AFTERNOON AND EVENING APPEAR VERY LOW DUE TO THE OVERALL LACK IN INSTABILITY...BUT THE RAP ANALYSIS PROXIMITY SOUNDINGS ALSO INDICATE VERY DEEP INVERTED-V SOUNDINGS ACROSS MUCH OF THE CWA WHICH WILL BE CONDUCIVE FOR BRIEF DOWN BURSTS DESPITE THE GENERALLY WEAK CONVECTION. GIVEN ALL THIS...WILL ALSO GO AHEAD AND INTRODUCE STRONG STORM WORDING...BRIEF WIND GUSTS TO AROUND 50 MPH...TO THE HWO FOR THIS AFTERNOON AND EVENING...AGAIN PRIMARILY FOR LOCATIONS ACROSS OUR WESTERN AND NORTHERN CWA. TEMPERATURES ARE STILL SOMEWHAT DIFFICULT TO PIN DOWN FOR THIS AFTERNOON. MOST LOCATIONS ACROSS THE CWA AS OF MIDDAY ARE IN THE 70S TO NEAR 80...AND WITH EXPANSIVE CLOUD COVER INFILTRATING THE AREA ITS HARD TO BELIEVE TEMPERATURES WILL RISE MUCH MORE THAN 10-13 DEGREES. THAT BEING SAID...THE CURRENT FORECAST ONLY HAS AFTERNOON HIGHS RISING INTO THE LOW TO MID 80S ACROSS OUR NORTHEAST...AND INTO THE LOW 90S ACROSS OUR SOUTHWEST. CERTAINLY HARD TO ARGUE WITH THE INHERITED HIGH TEMPERATURES SO WENT AHEAD AND LEFT THEM AS IS FOR TODAY. OVERALL THE FORECAST FOR TODAY IS IN GREAT SHAPE AND THE ONLY CHANGES MADE TO THE FORECAST...OTHER THAN THE ADDITION OF POPS FOR THIS AFTERNOON AND EVENING...WAS TO TWEAK HOURLY SKY...DEW POINT AND WIND GRIDS TO BETTER REFLECT CURRENT CONDITIONS. && .PREV DISCUSSION... /ISSUED 1226 PM CDT SAT AUG 11 2012/ AVIATION...18Z KGRI TAF. VFR CONDITIONS EXPECTED THROUGH THE NEXT 24 HOURS. MID LEVEL CLOUDS WILL PERSIST AT THE TERMINAL THROUGH MUCH OF THE TAF PERIOD...BUT NOTHING BELOW 8000FT AGL CURRENTLY EXPECTED. SHOWERS WITH EMBEDDED THUNDERSTORMS WILL BE OBSERVED ACROSS PORTIONS OF THE REGION TONIGHT AND AS A RESULT...WILL GO AHEAD WITH PROB30 TSRA 03Z-06Z...AND PREVAILING TSRA 06Z-09Z. THERE MAY BE SOME ISOLATED CONVECTION NEAR THE TERMINAL THIS AFTERNOON AND EVENING AS WELL...BUT AT THIS TIME THE PROBABILITY OF MEASURABLE PRECIPITATION BEING REALIZED AT KGRI THIS AFTERNOON AND EVENING IS FAR TOO LOW FOR INSERTION INTO THE TAF AT THIS TIME. PRECIPITATION SHOULD QUICKLY DEPART TO THE EAST OF THE TERMINAL BY 09Z SUNDAY WITH CLEARING SKIES OBSERVED SHORTLY THEREAFTER. MINOR VISIBILITY RESTRICTIONS TO AROUND 6SM WILL BE POSSIBLE IN PRECIPITATION 03Z-09Z. PREV DISCUSSION... /ISSUED 400 AM CDT SAT AUG 11 2012/ SHORT TERM...THROUGH 12Z TUESDAY...AN UPPER LEVEL DISTURBANCE ACROSS THE NORTHERN ROCKIES THIS MORNING IS EXPECTED TO EJECT INTO THE NORTHERN PLAIN THIS AFTERNOON AND EVENING...HELPING TO STEER A LOW LEVEL TROUGH OF LOW PRESSURE ACROSS THE LOCAL AREA THIS EVENING AND OVERNIGHT...WHICH MAY PROVIDE ENOUGH FORCING FOR SOME SCATTERED SHOWERS AND THUNDERSTORMS. WHILE BEST SHOWER AND THUNDERSTORM CHANCES APPEAR TO BE TO THE WEST OF THE LOCAL AREA DURING THE MID/LATE AFTERNOON HOURS...EXPECT A FEW SHOWERS TO REMAIN IN TACT AND CROSS PORTIONS OF SOUTH CENTRAL NEBRASKA AND NORTH CENTRAL KANSAS THIS EVENING AND OVERNIGHT. WHILE JUST ABOUT ALL THE MODELS ARE PAINING SOME SCATTERED PRECIP ACROSS THE AREA OVER THIS TIME PERIOD...OVERALL QPF VALUES APPEAR TO BE FAIRLY MODEST...WITH UNDER ONE HALF AN INCH OF TOTAL PRECIPITATION EXPECTED IN THE WETTEST SPOTS. THIS IS SUPPORTED BY ONLY MARGINAL SHEAR AND INSTABILITY FORECAST ACROSS THE LOCAL AREA TONIGHT...WITH MAINLY UNORGANIZED SHOWERS AND THUNDERSTORMS WITH VERY LOW SEVERE POTENTIAL EXPECTED AS A RESULT. TEMPERATURES THIS AFTERNOON MAY BE A LITTLE TRICKY...AS WITH INCREASED CLOUD COVER WOULD EXPECT AFTERNOON TEMPERATURES TO BE HELD DOWN A FEW DEGREES FROM THEIR POTENTIAL...HOWEVER 850 MB TEMPS WARM AHEAD OF THE LOW LEVEL TROUGH SLIGHTLY FROM FRIDAY READINGS...SO WHILE NUDGED DOWN AFTERNOON TEMPS A COUPLE OF DEGREES FROM PREVIOUS FORECAST...KEPT FORECAST HIGHS ABOVE FRIDAYS NICE READINGS. THEREAFTER...A DRY COLD FRONT IS EXPECTED TO DROP SOUTHWARD ACROSS THE CENTRAL PLAINS SUNDAY AFTERNOON...WHICH SHOULD HELP TO MAINTAIN THE CURRENT STRING OF SEASONABLY COOL SUMMER TEMPERATURES TO ROUND OUT THE SHORT TERM FORECAST PERIODS...WITH THE NEXT APPROACHING UPPER LEVEL DISTURBANCE EXPECTED TO BRING A SLIGHT CHANCE OF SOME SHOWERS AND THUNDERSTORMS TO THE REGION LATE MONDAY NIGHT. WINDS WILL ALSO INCREASE OUT OF THE NORTH ON SUNDAY WITH THE PASSING COLD FRONT...BUT RELATIVE HUMIDITIES AT THIS TIME APPEAR TO REMAIN HIGH ENOUGH TO AVOID ANY CRITICAL FIRE WEATHER CONDITIONS AT THIS TIME. LONG TERM...12Z TUESDAY THROUGH FRIDAY. OVERALL LITTLE NOTABLE CHANGE WAS MADE TO THE BIG PICTURE DURING THIS 4-DAY PERIOD...WHICH WILL BE MARKED BY A CONTINUED WELCOME STRETCH OF NEAR-NORMAL TO BELOW NORMAL TEMPERATURES...ALONG WITH A FEW CHANCES FOR AT LEAST SPOTTY RAINFALL...AND MAYBE A SHOT AT MORE WIDESPREAD RAINFALL ESPECIALLY WED NIGHT. AS DISCUSSED LAST NIGHT...THE DOWNWARD TRENDING OF HIGH TEMPS FOR THURSDAY CONTINUES. STARTING OUT TUESDAY/TUESDAY NIGHT...LEFT AT LEAST 20 POPS GOING CWA-WIDE THE ENTIRE TIME...WITH SLIGHTLY HIGHER 30 PERCENT CHANCES FOCUSED WITHIN THE EASTERN HALF OF THE AREA. THE 00Z ECMWF/GFS DETERMINISTIC SOLUTIONS ARE FAIRLY CONSISTENT ON THE SYNOPTIC SCALE SCENE ALOFT...WITH WEST-NORTHWEST FLOW OVER THE AREA IN BETWEEN THE SUBTROPICAL RIDGE AXIS WELL TO THE SOUTH OVER THE SOUTHERN CONUS...AND A DEEPENING SHORTWAVE TROUGH PASSING FROM SOUTHWEST CANADA TOWARD THE NORTHERN ROCKIES/NORTHERN PLAINS. RIGHT OFF THE BAT THOUGH...THERE ARE SOME INCONSISTENCIES...AS THE ECMWF SOLUTION DEPICTS LINGERING DAYTIME SHOWERS/STORMS ASSOCIATED WITH A LOW AMPLITUDE DEPARTING SHORTWAVE BUT A DRY NIGHT...WHILE THE GFS AND ITS ENSEMBLE MEAN SHOW LIMITED SUPPORT FOR DAYTIME PRECIP BUT A BIT BETTER SIGNAL FOR TUES NIGHT. FOR NOW...THE BEST APPROACH SEEMS TO BE LEAVING THE 20-30 PERCENT CHANCES GOING...WITH PLENTY OF TIME STILL FOR REFINEMENT OR REMOVAL. NO MATTER...NOT SEEING MUCH OF A SEVERE WEATHER THREAT WITH ANY STORMS DURING THIS TIME FRAME DUE TO LIMITED INSTABILITY...ALTHOUGH SEASONALLY TYPICAL SMALL HAIL/GUSTY WIND NOT OUT OF THE QUESTION GIVEN AT LEAST MODEST DEEP LAYER SHEAR AT LEAST 25-35KT. TEMP WISE...MADE ALMOST NO CHANGE TO THE HIGHS OR LOWS...WITH MOST OF THE CWA TOPPING OUT BETWEEN 83-90 DURING THE DAY. WEDNESDAY/WEDNESDAY NIGHT...THIS IS BY FAR THE MOST INTERESTING 24 HOURS OF THE PERIOD...AS BOTH THE ECMWF/GFS SWING THE POSITIVELY TILTED SHORTWAVE TROUGH AXIS FROM THE NORTHERN ROCKIES/PLAINS TOWARD THE CENTRAL PLAINS...ALTHOUGH THE ECMWF ADVERTISES AN OVERALL SHARPER/STRONGER WAVE WITH A STRONGER UPPER LEVEL JET ALONG ITS LEADING EDGE. IN THE LOW LEVELS HOWEVER...BOTH MODELS ARE IN VERY GOOD AGREEMENT BRINGING A COLD FRONT INTO AT LEAST NORTHWEST PORTIONS OF THE CWA LATE IN THE DAY...BEFORE PUSHING IT ALL THE WAY THROUGH THE AREA IN A DECENTLY FORCED MANNER WED NIGHT. AHEAD OF THIS BOUNDARY...MOST OF THE DAY IS ANTICIPATED TO BE DRY AND CAPPED WITH SOUTHERLY SURFACE WINDS RESULTING IN WHAT SHOULD BE THE WARMEST DAY OF THE WEEK...AND MADE ESSENTIALLY NO CHANGE TO HIGH TEMPS WITH MAINLY UPPER 80S NEB ZONES...AND LOW-MID 90S IN KS. BY LATE AFTERNOON...COULD THEN SEE A CORRIDOR OF STRONG TO POTENTIALLY SEVERE STORMS ERUPT IN OR VERY NEAR THE CWA ALONG THIS FRONT...WITH MORE WIDESPREAD ACTIVITY THEN DEVELOPING MAINLY BEHIND THE FRONT WED EVENING/NIGHT AS THE CWA BECOMES ALIGNED WITHIN THE ENTRANCE REGION OF A 300MB JET STREAK EXTENDING FROM THE DAKOTAS INTO QUEBEC. ALTHOUGH NOT LOOKING LIKE A WIDESPREAD SEVERE WEATHER EVENT AT THIS POINT...AT LEAST A FEW SEVERE STORMS CERTAINLY NOT OUT OF THE QUESTION GIVEN SUCH STRONG FORCING AND INCREASING POST-FRONTAL DEEP LAYER SHEAR. POP-WISE...KEPT ONLY SLIGHT 20S GOING THROUGH THE DAY...AGAIN MAINLY FOR AFTERNOON POTENTIAL...BUT INCREASED NIGHT PERIOD TO CHANCE 30S FOR NOW...WITH FURTHER INCREASES LIKELY IF TRENDS HOLD. THURSDAY/THURS NIGHT...THE SOUTHERN END OF THE SHORTWAVE AXIS QUICKLY SLIDES EAST OF THE REGION...CARVING OUT A LONGWAVE TROUGH OVER THE EASTERN HALF OF THE CONUS BY FRIDAY MORNING AS RIDGING DOMINATES THE WESTERN STATES...LEAVING THE LOCAL AREA UNDER SEASONABLY STRONG NORTHWEST FLOW. FOR THE DAYTIME...INTRODUCED SOME 20-30 POPS ACROSS MAINLY KS ZONES TO ACCOUNT FOR DEPARTING PRECIP. FOR NOW LEFT A THUNDER MENTION WITH THIS ACTIVITY...BUT LATER SHIFTS MAY CONSIDER CONVERTING TO ONLY SHOWER WORDING AS INSTABILITY SHOULD BE ON THE WANE BY THEN. CONFIDENCE IS THEN RATHER HIGH IN A DRY THURS NIGHT PERIOD AS COOL HIGH PRESSURE BUILDS IN AT THE SURFACE. TEMP-WISE...LOWERED HIGHS ANOTHER 3-4 DEGREES...NOW ADVERTISING ONLY UPPER 70S NORTH TO MID 80S SOUTH...WHICH STILL MIGHT NOT BE COOL ENOUGH. ALONG THOSE SAME LINES...THE CURRENTLY ADVERTISED LOWS IN THE 50S THURS NIGHT COULD END UP BEING IN THE 40S SOME AREAS IF SKIES ARE CLEAR AND THE SURFACE RIDGE AXIS SETS UP ACROSS OR VERY NEAR THE CWA AS CURRENTLY DEPICTED. FRIDAY DAYTIME...CONFIDENCE IS CURRENTLY RATHER HIGH FOR BEING 6 DAYS OUT IN A DRY AND PLEASANT END TO THE WORK-WEEK AS DRY NORTHERLY FLOW PREVAILS ALOFT...AND THE SURFACE RIDGE AXIS SLOWLY MIGRATES EAST ACROSS THE REGION. KEPT SEASONABLY COOL HIGHS ALMOST UNCHANGED...WITH MOST NEB ZONES ONLY UPPER 70S...AND MORE SO LOW- MID 80S IN KS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ 125 PM UPDATE/AVIATION...BRYANT SHORT TERM...ROSSI LONG TERM...PFANNKUCH
AREA FORECAST DISCUSSION
NWS ABERDEEN SD
1227 PM CDT SAT AUG 11 2012 .UPDATE... JUST A QUICK UPDATE TO EXPAND COVERAGE OF LIGHT RAIN SHOWERS. MOST AREAS HAVE ONLY RECEIVED A FEW HUNDREDTHS THUS FAR...WITH A DRY LAYER BELOW 10KFT. SOME DIFFERENCES IN MODEL TIMING HAVE ARISEN WITH THIS MORNINGS SUITE OF GUIDANCE...THE HRRR PUSHING THE SYSTEM THROUGH QUICKLY...WHILE THE NAM/SREF/GFS A MUCH SLOWER PROGRESSION. AT THIS POINT...WILL NOT TINKER WITH THE TIMING/COVERAGE FOR THIS EVENING/OVERNIGHT GIVEN UNCERTAINTY. DO EXPECT THAT AS WE CONTINUE TO MOISTEN UP THE DRY LAYER...AND THE ASSOCIATED WAVE STRENGTHENS OVER WESTERN SOUTH DAKOTA...PRECIPITATION WILL INTENSITY AND INCREASE IN COVERAGE. ALSO DROPPED HIGH TEMPERATURES A FEW DEGREES WITH WIDESPREAD CLOUD COVER/RAIN. && .PREVIOUS DISCUSSION... .SHORT TERM...TODAY THROUGH MONDAY CHILLY AND GENERALLY WET CONDITIONS ARE EXPECTED FOR THE WEEKEND ACROSS THE NORTHERN PLAINS. THE AREA OF HIGH PRESSURE THAT BROUGHT SEASONALLY COOL CONDITIONS TO THE EASTERN DAKOTAS FOR THE PAST FEW DAYS WILL GRADUALLY BE REPLACED BY A LOW PRESSURE SYSTEM. THIS LOW PRESSURE SYSTEM WILL HAVE SOME DRY AIR TO OVER COME BELOW 700 MB...WITH MODELS NOW PCPN REACHING THE I-29 CORRIDOR CLOSER TO 0Z SUNDAY. THIS SLOW PROGRESSION SEEMS PRETTY LIKELY GIVEN SHOWERS HAVE BEEN ONGOING ALL NIGHT IN WESTERN SD...WITH LITTLE ADVANCEMENT TOWARD THIS CWA. THE BEST TIMING FOR PCPN FOR THE CWA APPEARS TO BE TONIGHT THROUGH SUNDAY. MODELS ARE SUGGESTING THE SURFACE AND UPPER LEVEL LOW WILL BE NEARLY VERTICALLY STACKED OVER SOUTHERN SD WITH DECENT WAA FLOW WRAPPING NORTHWARD INTO THIS CWA. WITH 850 MB TEMPS ONLY IN THE LOWER TEENS...ALONG WITH CLOUDY SKIES...HIGH TEMPERATURES ON SUNDAY WILL LIKELY STRUGGLE TO REACH THE MID 60S IN THE EASTERN HALF OF THE CWA. THE LOW PRESSURE SHOULD FINALLY EXIT THE REGION BY MONDAY MORNING...WITH DRY CONDITIONS EXPECTED TO START THE WORK WEEK. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY MAIN FORECAST CHALLENGE DURING THE EXTENDED WILL BE THE SFC COLD FRONT THAT WILL MOVE THROUGH THE DAKOTAS MID WEEK. ENHANCED BY SHORTWAVE ACTIVITY AND WITH GOOD SHEAR...SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TUESDAY NIGHT THROUGH WEDNESDAY. H85 TEMPS IN THE LOWER 20S WILL PLUMMET INTO THE UPPER SINGLE DIGITS BEHIND THE FRONT. TEMPERATURES NEAR NORMAL AT THE START OF THE PERIOD WILL FALL TO 5 TO 10 DEGREES BELOW AVERAGE THURSDAY THROUGH SATURDAY. && .AVIATION... 18Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS A SYSTEM WILL SLOWLY MOVE ACROSS THE REGION THROUGH THE AFTERNOON...OVERNIGHT...AND INTO MINNESOTA SUNDAY. MAINLY ANTICIPATE VFR CONDITIONS ALONG WITH SOUTH/SOUTHEAST WINDS OVER THE NEXT SEVERAL HOURS. OVERNIGHT AND INTO SUNDAY AM...COULD EXPERIENCE INTERMITTENT MVFR CIGS/VISBY ALTHOUGH HAVE HIGH UNCERTAINTY OVER WHERE/WHEN. BEST CHANCE FOR MVFR CONDITIONS DEPEND MAINLY ON TIMING OF MAIN RAIN BAND AND WRAP AROUND CLOUD COVER...WITH LESS LIKELIHOOD ASSOCIATED WITH THE SURROUNDING SHOWER ACTIVITY. WINDS ON THE BACK SIDE OF THE SYSTEM WILL PICK UP AROUND 15 TO 25MPH OUT OF THE NORTHWEST. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...CONNELLY SHORT TERM...SD LONG TERM...WISE AVIATION...CONNELLY WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
258 PM CDT SAT AUG 11 2012 .SHORT TERM...TONIGHT AND SUNDAY LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE STRETCHING ALONG THE MISSISSIPPI VALLEY TO HUDSON BAY WHILE LOW PRESURE IS MOVING OVER THE DAKOTAS AND ALSO LAKE ERIE. WITH HIGH PRESSURE OVER THE REGION...MOSTLY CLEAR SKIES HAVE PREVAILED ACROSS THE FORECAST AREA THROUGH EARLY THIS AFTERNOON. MID AND HIGH CLOUDS ARE ALREADY ADVANCING ACROSS THE NORTHERN MISSISSIPPI VALLEY AHEAD OF THE NEXT STORM SYTEM OVER THE NORTHERN PLAINS. AS THE STORM SYSTEM CONTINUES TO MOVE EAST...LIGHT PRECIP CHANCES TOMORROW ALONG WITH CLOUDS AND TEMPS ARE THE MAIN FORECAST CONCERNS. TONIGHT...HIGH PRESSURE WILL REMAIN AT THE SURFACE ACROSS THE WESTERN GREAT LAKES TONIGHT. HOWEVER...A SHORTWAVE TROUGH OVER THE NORTHERN PLAINS WILL MOVE INTO THE NORTHERN MISSISSIPPI VALLEY TONIGHT. A BLANKET OF MID AND HIGH CLOUDS WILL SPREAD ACROSS CENTRAL AND EASTERN PORTIONS OF THE STATE LATE THIS EVENING THROUGH THE OVERNIGHT. WITH DEWPOINTS MIXING OUT THIS AFTERNOON...POCKETS OF GROUND FOG SHOULD ONLY BE NUISANCE LATE AND NOT EXPECTING ANYTHING DENSE TO FORM. LOWS IN THE MID 40S NORTH TO MID 50S SOUTH. SUNDAY...THE SHORTWAVE WILL PROCEED TO MOVE INTO THE STATE AND WILL SEE A PRETTY THICK LAYER OF MID AND HIGH CLOUDS OVERHEAD. LOW LEVEL MOISTURE WILL HANG TO THE WEST THOUGH CLOSER TO A SURFACE LOW OVER IOWA. PROGGED SOUNDINGS REMAIN FAIRLY DRY BELOW 700MB...SO IF ANY PRECIP WERE TO FALL OUT OF THE MID DECK...IT SHOULD ONLY BE SPRINKLES. ADDED SPRINKLES OVER CENTRAL WISCONSIN FOR THE AFTERNOON. .LONG TERM...SUNDAY NIGHT THROUGH NEXT SATURDAY. MODELS ARE IN DECENT AGREEMENT WITH THE UPPER PATTERN THROUGH THE MIDDLE OF NEXT WEEK THEN THE GFS AND ECMWF DIFFER IN HOW THEY HANDLE A SIGNIFICANT UPPER TROUGH AS IT MOVES ACROSS THE GREAT LAKES. THE ECMWF HAS A SHARPER UPPER TROUGH AND CLOSES OFF AN UPPER LOW OVER LOWER MICHIGAN WHILE THE GFS TROUGH IS BROADER. A WEAK UPPER TROUGH MOVING ACROSS THE AREA SUNDAY NIGHT AND MONDAY SHOULD PRODUCE AT LEAST SCATTERED SHOWERS AND THUNDERSTORMS DESPITE THE SURFACE LOW BEING WELL SOUTH OF OUR AREA OVER ILLINOIS. HIGHS MONDAY COULD BE COOLER THAN WHAT WE CURRENTLY HAVE IN THE FORECAST IF SKIES ARE CLOUDY AND SHOWERS MORE ABUNDANT THAN NOW FORECAST. THEN NORTHWEST UPPER FLOW SHOULD PROVIDE FOR DRY AND SEASONABLE WEATHER FOR TUESDAY AND WEDNESDAY. A SIGNIFICANT UPPER TROUGH WILL APPROACH WEDNESDAY NIGHT AND THURSDAY AND PROVIDE SUFFICIENT UPPER SUPPORT FOR SHOWERS AND THUNDERSTORMS. MODELS SUGGEST THERE WILL BE DECENT MID LEVEL WINDS AND SHEAR BUT INSTABILITY IS MODEST. AFTER THAT GOES BY SOME COOLER THAN NORMAL AIR WILL ARRIVE FOR THE END OF THE WEEK. GFS FORECASTS SUBZERO 850 MB TEMPERATURES IN NORTHERN WISCONSIN FRIDAY AFTERNOON. && .AVIATION...HIGH PRESSURE AT THE SURFACE WILL PROVIDE MOSTLY CLEAR CONDITIONS THROUGH THIS EVENING. WILL THEN SEE INCREASING MID AND HIGH CLOUDS OVERNIGHT INTO SUNDAY AHEAD OF THE NEXT SYSTEM. CONDITIONS TO REMAIN VFR OVER THE PERIOD...THOUGH PATCHY IFR VSBYS IN GROUND FOG IS POSSIBLE OVER NORTH-CENTRAL WISCONSIN LATE TONIGHT. MPC && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ MPC/RDM