Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 08/19/13


SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NWS LOS ANGELES/OXNARD CA
815 PM PDT SUN AUG 18 2013 .SYNOPSIS... A SLIGHT CHANCE FOR THUNDERSTORMS ARE POSSIBLE IN THE SAN GABRIEL MOUNTAINS AND ANTELOPE VALLEY AGAIN TOMORROW...WITH THE UPPER LOW OFF THE CALIFORNIA COAST CONTINUING TO PULL SOME MONSOON MOISTURE INTO THE AREA FROM THE SOUTHEAST. THE UPPER LOW WILL BEGIN TO LIFT NORTHEAST ON THURSDAY...BUT WILL BE REPLACED BY ANOTHER TROUGH OF LOW PRESSURE MOVING IN FROM THE NORTHWEST. THE RESULT WILL BE CONTINUED NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES AND NIGHT THROUGH MORNING LOW CLOUDS ALONG THE COAST. && .SHORT TERM (TODAY-WED)... A FEW VERY IMPRESSIVE THUNDERSTORMS DEVELOPED ACROSS THE NORTHEAST PORTION OF LOS ANGELES COUNTY...MAINLY NORTH AND EAST OF PALMDALE TODAY. A COUPLE STORM CELLS WERE RIGHT ON THE LOS ANGELES...SAN BERNARDINO AND KERN COUNTY BORDER. CLOUD TOPS WERE AS HIGH AS 45000 FT WITH VERY IMPRESSIVE RAIN AND HAIL CORES EARLIER THIS AFTERNOON. LATEST NWS RADAR WAS SHOWING MOST OF THE CONVECTIVE ACTIVITY OCCURRING IN THE EASTERN PART OF SAN BERNARDINO COUNTY AND NORTH INTO KERN COUNTY OVER THE LAST HOUR AND LIKELY SETTLING DOWN OVER OUR AREA. MANY PARAMETERS CAME TOGETHER THIS AFTERNOON TO CAUSE THESE EXPLOSIVE THUNDERSTORMS. ALTHOUGH PRECIPITABLE WATERS (PWAT) VALUES WERE NOT THAT IMPRESSIVE AROUND 1.20" AND BEST MID LEVEL MOISTURE WAS ABOVE 600 MB (ABOVE 12000 FT). THE INSTABILITY LOOKED VERY IMPRESSIVE BY MID MORNING AS RAP SOUNDINGS OVER THE MOUNTAINS INDICATED CAPE VALUES WELL OVER 1000 J/KG. SINCE STORMS WERE ABLE TO INITIATE...THEY HAD NO PROBLEM GROWING VERTICALLY. RADAR RETURNS INDICATED VERY HIGH VIL (VERTICAL INTEGRATED LIQUID) AVAILABLE WITH THE STORM WHICH WAS A GOOD REASON WHY THERE WAS NICKEL SIZE HAIL REPORTED IN SOME HIGH DESERT LOCATIONS THIS AFTERNOON. BY LOOKING AT THE WATER VAPOR IMAGERY...IT IS EASY TO SPOT THE DIFFLUENT REGION OVER EASTERN LA COUNTY AND POINTS EAST AND NORTH BASED ON WHERE THE UPPER LOW WAS SITUATED TO HELP LIFT THESE STORMS AND EXPLODE LIKE THEY DID. THERE WAS AN IMPRESSIVE LANDSPOUT SPOTTED NEAR HELENDALE WHICH IS NORTH OF VICTORVILLE IN SAN BERNARDINO COUNTY. AS THE UPPER LOW BEGINS TO PIVOT FARTHER OFFSHORE THIS EVENING...THERE LOOKS TO BE SOME POTENTIAL FOR A FEW NOCTURNAL SHOWERS OVER THE COASTAL WATERS N OF POINT CONCEPTION. I MIGHT ADD SLIGHT CHANCE FOR THUNDERSTORMS FOR AREAS N OF POINT CONCEPTION...BUT NOT VERY CONFIDENT. AS FAR AS THE LOWER AND MORE STABLE PART OF THE ATMOSPHERE...(THE MARINE LAYER) WAS AROUND 1000 FT DEEP EARLY THIS EVENING...WHICH IS A BIT DEEPER THEN LAST NIGHT. WITH THE UPPER LOW JUST OFF THE CENTRAL COAST...THERE WILL BE A SLIGHT DEEPENING OF THE MARINE LAYER WHICH WILL ALLOW FOR SOME LOW CLOUDS TO CREEP INTO THE SAN GABRIEL AND POSSIBLY THE SAN FERNANDO VALLEY AFTER MIDNIGHT. TODAY`S HIGH TEMPS WERE OVERALL A TAD LOWER...BUT A FEW INTERIOR AREAS WERE AROUND THE SAME AS YESTERDAY. LONG BEACH WAS MUCH COOLER TODAY AT ONLY 74 COMPARED TO 86 ON SATURDAY DUE TO A PERSISTENT SOUTHERLY FLOW AND LOW CLOUDS HANGING AROUND. FOR MONDAY...NOT MUCH MOVEMENT IS EXPECTED WITH CUTOFF LOW...BUT THERE WILL CONTINUE TO BE SOME MODEST MID LEVEL MOISTURE ADVECTING NORTH OVER EASTERN LA COUNTY AND AREAS TO THE EAST. BOTH THE NAM-WRF AND GFS ARE INDICATING MORE INSTABILITY OVER THE LA COUNTY MOUNTAINS...HAVE ADDED A SLIGHT CHANCE OF THUNDERSTORMS FOR THE EASTERN PORTION OF THE SAN GABRIEL VALLEY AND ANTELOPE VALLEY ONCE AGAIN. THERE WILL BE LESS MOISTURE TO WORK WITH...BUT A SLIGHT CHANCE SEEMS REASONABLE FOR TOMORROW AFTERNOON AND EARLY EVENING. AT THE LEAST EXPECT PARTLY CLOUDY SKIES WITH SOME CUMULUS BUILDUPS IN THE MOUNTAINS AND OVER THE ANTELOPE VALLEY. LOOK FOR A MODEST COOLING TREND FOR TOMORROW AS THE UPPER RIDGE WEAKENS A BIT...ESPECIALLY ACROSS THE NORTHERN PORTION OF THE FORECAST AREA N OF POINT CONCEPTION. THERE WILL LIKELY BE SOME HIGH CLOUDS MOVING TO THE NORTH ACROSS THE SKY...BUT WILL CONTINUE WITH MOSTLY SUNNY SKIES. THE MID SHIFT CAN ADJUST IF NEED BE. ***FROM PREVIOUS DISCUSSION*** VERY LITTLE CHANGE TUE/WED. POSSIBLY SOME HIGH CLOUDS MOVING THROUGH AT TIMES TUESDAY AS MOISTURE WRAPS AROUND THE STILL STATIONARY UPPER LOW. BUT AT THIS TIME NOT SEEING ANYTHING TO WARRANT POPS OR EVEN PARTLY CLOUDY SKIES. DAYTIME HIGHS EXPECTED TO CHANGE LITTLE. .LONG TERM (THU-SUN)...UPPER LOW FINALLY EXITING THE STATE ON THURSDAY TO BE REPLACED BY A WEAK TROF THROUGH THE WEEKEND. THE ECMWF IS DEEPER WITH THE TROF AND THUS COOLER AS WELL. FOR NOW WILL JUST INDICATE LITTLE CHANGE THROUGH THE PERIOD WITH HIGHS NEAR TO SLIGHTLY BELOW SEASONAL NORMS. ALL MODEL SOLUTIONS KEEP MONSOON MOISTURE WELL EAST INTO EARLY NEXT WEEK. && .FIRE... A CUTOFF LOW PRESSURE SYSTEM OFF THE CENTRAL COAST WILL REMAIN NEARLY STATIONARY THROUGH TUESDAY. THIS LOW PRESSURE SYSTEM IS DRAWING SOME MOISTURE INTO SOUTHERN AND CENTRAL CALIFORNIA. AT THE PRESENT TIME...THE MOISTURE AXIS IS FOCUSED ACROSS EASTERN LOS ANGELES COUNTY AND POINTS EASTWARD. THIS INFLUX OF MOISTURE COMBINED WITH AN UNSTABLE AIR MASS WILL CONTINUE TO GENERATE ISOLATED THUNDERSTORMS ACROSS THE EASTERN PORTIONS OF THE SAN GABRIEL MOUNTAINS AND ANTELOPE VALLEY THROUGH THIS EVENING. THESE STORMS WILL HAVE THE POTENTIAL TO PRODUCE STRONG DOWNDRAFT WINDS...HAIL...AND BRIEF HEAVY DOWNPOURS. AROUND THE PERIPHERY OF STORMS...ISOLATED DRY LIGHTNING STRIKES WILL BE POSSIBLE. CLOSER TO THE CLOSED LOW...THERE IS A VERY SLIGHT CHANCE OF STORMS TONIGHT INTO MONDAY FOR AREAS NORTH OF POINT CONCEPTION. THE LOW PRESSURE SYSTEM WILL BRING GUSTY SOUTHERLY WINDS TO INTERIOR SECTIONS THROUGH MONDAY. WITH THE EXCEPTION OF EASTERN LOS ANGELES COUNTY...REMAINING AREAS ARE FORECASTED TO BE QUITE DRY AT LOWER ELEVATIONS. THIS COMBINATION OF GUSTY SOUTHERLY WINDS...LOW HUMIDITIES...VERY WARM TEMPERATURES...AND VERY DRY FUELS WILL CONTINUE TO BRING ELEVATED FIRE DANGER ACROSS INLAND AREAS THROUGH MONDAY. BRIEF CRITICAL FIRE WEATHER CONDITIONS WILL BE LIKELY THROUGH MONDAY ACROSS THE MOUNTAINS. && .AVIATION...19/00Z. WILL GO WITH PERSISTENCE ONCE AGAIN IN RESPECT TO STRATUS AND FOG OVER THE NEXT 24 HOURS. HIGH CONFIDENCE WITH LIFR/IFR CIGS FOR COASTAL AREAS...WITH SOME VLIFR CONDS FOR A FEW COASTAL SITES. TIMING FOR LOW CLOUDS WILL BE MODERATE IN CONFIDENCE +/-2 HOURS AS WELL AS SCOUR OUT TIMES MON MORNING. LATEST AMDAR SOUNDING NEAR KLAX SHOWED A STRONG INVERSION AROUND 1200 FT DEEP. WITH THE MARINE LAYER THIS DEEP...THERE WILL BE A 30 PERCENT CHANCE THAT KBUR AND KVNY WILL EXPERIENCE IFR/LIFR CIGS AFTER 10Z TONIGHT. KLAX...HIGH CONFIDENCE FOR IFR/MVFR CIGS TO PERSIST THROUGH THE OVERNIGHT HOURS. 30 PERCENT CHANCE FOR CIGS TO SCOUR OUT +/- W HOURS FROM 00Z TAF. KBUR...HIGH CONFIDENCE WITH 00Z TAF THROUGH 10Z. THEN 30 PERCENT CHANCE FOR LIFR/IFR CIGS AFTER 10Z THROUGH 15Z. && .LOX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ PUBLIC...KAPLAN/MW FIRE...GOMBERG AVIATION...CK SYNOPSIS...SUKUP WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION...UPDATED
NWS RENO NV
802 PM PDT SUN AUG 18 2013 .UPDATE...SHORT TERM AND FIRE WEATHER UPDATED FORECAST TO INCLUDE ISOLATED THUNDERSTORMS NORTHERN AREAS THIS EVENING AS CONVECTION WAS DEVELOPING OVER FAR NORTHERN WASHOE COUNTY. STORMS HAVE PRODUCED SIGNIFICANT AMOUNTS OF LIGHTNING MUCH LIKE THEY DID SATURDAY. SATELLITE AND RADAR IMAGERY SHOWS SHORTWAVE MOVING NORTHWEST INTO WESTERN NV THIS EVENING AND THIS WILL LIKELY RESULT IN ANOTHER ROUND OF THUNDERSTORMS THIS EVENING ESPECIALLY SOUTH OF HIGHWAY 50. ADDED THUNDERSTORMS OVERNIGHT AS WELL GIVEN THE ELEVATED INSTABILITY AND LIFT, ALTHOUGH COVERAGE OF LIGHTNING SHOULD DECREASE. THUNDERSTORMS WILL BE MORE ELEVATED OVERNIGHT AND MORE CONDUCIVE TO DRY STRIKES. THE OTHER PROBLEM WILL BE THE SMOKE AS OUTFLOW PUSHED SMOKE BACK INTO THE RENO-CARSON CITY AREA. OUTFLOW WAS COLLIDING WITH GUST FRONT AND ASSOCIATED DUST MOVING WESTWARD THROUGH PERSHING AND CHURCHILL COUNTIES. VISIBILITY IN BOTH AREAS HAS BEEN AS LOW AS 2 MILES, POSSIBLY LOWER IN LOCALIZED AREAS. UNFORTUNATELY THE EAST OUTFLOW WILL MOST LIKELY NOT MAKE IT FAR ENOUGH WEST TO PUSH THE SMOKE BACK OUT OF THE AREA. SO WE WILL HAVE TO WAIT FOR MIXING AND SOUTHEAST FLOW TO HELP THINGS IMPROVE ON MONDAY. SO UPDATED TO PUT SMOKE ALONG THE SIERRA FRONT AND TAHOE BASIN THROUGH MONDAY MORNING. HOHMANN && .PREVIOUS DISCUSSION... /ISSUED 201 PM PDT SUN AUG 18 2013/ SYNOPSIS... SHOWERS AND THUNDERSTORMS WILL INCREASE THIS AFTERNOON AND CONTINUE THROUGH THURSDAY AS LOW PRESSURE OFF THE CENTRAL CALIFORNIA COAST REMAINS IN PLACE BEFORE MOVING INLAND BY MIDWEEK. THE STRONGER STORMS WILL PRODUCE HEAVY RAINFALL, HAIL AND FREQUENT LIGHTNING. ABOVE NORMAL TEMPERATURES ARE EXPECTED ON MONDAY, BEFORE COOLING BACK TO NEAR SEASONAL NORMALS FOR THE REMAINDER OF THE UPCOMING WEEK. SHORT TERM... CURRENT WATER VAPOR IMAGERY SHOWS THE UPPER LOW PARKED JUST OFF THE CALIFORNIA COASTLINE NEAR MONTEREY BAY. SOUTHERLY FLOW BETWEEN THIS LOW AND HIGH PRESSURE ACROSS SOUTHERN NEW MEXICO HAS ALLOWED MOISTURE TO SURGE NORTH ACROSS SOUTHERN CALIFORNIA AND SOUTHERN NEVADA WITH THE 12Z RAOB AT LAS VEGAS REPORTING A PRECIPITABLE WATER VALUE OF 1.17 INCHES. MODEL GUIDANCE IS IN GOOD AGREEMENT THAT THE UPPER LOW WILL REMAIN JUST OFF THE CENTRAL CALIFORNIA COASTLINE THROUGH WEDNESDAY WITH MOISTURE INCREASING ACROSS THE SIERRA AND WESTERN NEVADA. THE MAIN CHALLENGE IN THE SHORT TERM WILL BE TIMING THE INDIVIDUAL SHORT WAVES THAT ROTATE AROUND THE UPPER LOW AND PROVIDE FORCING FOR THUNDERSTORM ACTIVITY. THE BEST CHANCE OF THUNDERSTORMS THIS AFTERNOON WILL BE NEAR THE SIERRA CREST IN MONO AND ALPINE COUNTIES. RECENT RUNS OF THE SHORT TERM HRRR MODEL SUGGEST A BROADER AREA OF CONVECTION WILL DEVELOP ACROSS MONO AND MINERAL COUNTIES AND LIFT TO THE NORTHWEST TOWARDS THE INTERSTATE 80 CORRIDOR THIS EVENING. THE 12Z NAM DEPICTS A VERY WEAK SHORTWAVE ROTATING AROUND THE UPPER LOW ACROSS WESTERN NEVADA THIS EVENING WHICH MAY ACT AS THE FORCING FOR THIS CONVECTION. GIVEN THE RUN TO RUN CONSISTENCY OF THE HRRR THIS MORNING...DECIDED TO INCREASE POPS ACROSS MONO AND MINERAL COUNTIES THROUGH MIDNIGHT. SCATTERED THUNDERSTORMS ARE POSSIBLE ACROSS THE ENTIRE FORECAST AREA ON MONDAY AS MODEL PRECIPITABLE WATER VALUES INCREASE TO 0.75 INCHES NEAR RENO. WITH THE STORMS TURNING WETTER AND STORM MOTIONS AROUND 10 KTS, THE MAIN CONCERN WILL BE LOCALLY HEAVY RAIN AND THE POTENTIAL FOR FLASH FLOODING. MOISTURE WILL INCREASE FURTHER ON TUESDAY WITH MODEL PRECIPITABLE WATER VALUES NEAR 0.95 INCHES ACROSS WESTERN NEVADA. A FLASH FLOOD WATCH MAY BE NECESSARY ON TUESDAY AS THE DEEP MOISTURE WILL BE WELL ESTABLISHED AND STORM MOTIONS WILL REMAIN SLOW (AROUND 10 KTS). AREAS OF SMOKE HAVE BEEN ADDED TO THE FORECAST GRIDS FOR THIS AFTERNOON AND EVENING IN THE CARSON AND WASHOE VALLEYS DUE TO THE BRUNSWICK FIRE LOCATED TO THE EAST OF CARSON CITY. ALSO INCLUDED MENTION OF SMOKE ACROSS PORTIONS OF SOUTHERN LYON, WESTERN MINERAL AND EAST CENTRAL MONO COUNTIES THANKS TO SPRING PEAK WILDFIRE LOCATED TO THE EAST OF BODIE. MYRICK LONG TERM...WEDNESDAY THROUGH SUNDAY... THERE IS STILL GOOD AGREEMENT AMONG MEDIUM RANGE MODELS WITH THE LOW LIFTING NORTH ACROSS NORTHERN CALIFORNIA WEDNESDAY INTO THURSDAY AND MOVING INTO SOUTHERN OREGON AS AN OPEN WAVE BY THURSDAY NIGHT OR FRIDAY MORNING. THUNDERSTORMS WILL CONTINUE TO BE A THREAT THROUGH THURSDAY WITH THE BEST CHANCES IN NORTHEAST CALIFORNIA AND NORTHWEST NEVADA NORTH OF HIGHWAY 50 WHERE THERE IS DIFLUENT FLOW ALOFT AND THE BEST DYNAMICS AND LIFT. HEAVY RAIN IS THE GREATEST CONCERN WEDNESDAY AND THURSDAY AS PRECIPITABLE WATER VALUES REMAIN AT 0.8-1.0 INCH. WHILE STORM MOTIONS DO INCREASE BY THURSDAY, TRAINING AND/OR BACK BUILDING STORMS COULD STILL PRODUCE AREAS OF HEAVY RAIN. HAIL AND GUSTY OUTFLOW WINDS ARE ALSO POSSIBLE. DRY AND STABLE SOUTHWEST FLOW RESULTS ACROSS THE AREA BEHIND THE EXITING LOW, ENDING ALL THUNDERSTORM CHANCES THROUGH THE WEEKEND AND KEEPING SKIES MOSTLY CLEAR. BREEZY AFTERNOON WINDS ARE EXPECTED EACH DAY, BUT GUSTS SHOULD BE AT OR BELOW 30 MPH. TEMPERATURES WILL BE SLIGHTLY BELOW NORMAL WEDNESDAY AND THURSDAY, ESPECIALLY ACROSS NORTHEAST CALIFORNIA CLOSER TO THE CORE OF THE LOW. HIGHS WILL REBOUND TO NEAR NORMAL FOR THE WEEKEND. DJ AVIATION... CONVECTIVE TOWERS HAVE DEVELOPED THIS AFTERNOON ALONG THE SIERRA CREST SOUTH OF LAKE TAHOE. THE BEST CHANCE OF STORMS THROUGH 00Z WILL BE AT KMMH, KTRK AND KTVL. THE MAIN THREATS FROM ANY STORMS THAT FORM WILL BE ERRATIC AND GUSTY WINDS, LOCALLY HEAVY RAIN AND SMALL HAIL. A COMPLEX OF SHOWERS AND THUNDERSTORMS MAY LIFT NORTHWEST ACROSS WESTERN NEVADA BETWEEN 00-09Z IMPACTING KCXP AND KRNO, BUT CONFIDENCE IN TIMING AND LOCATION AT THIS TIME IS LOW. SMOKE FROM THE BRUNSWICK FIRE TO THE EAST OF CARSON CITY MAY REDUCE SLANTWISE VISIBILITIES AT KCXP AND KRNO THROUGH THIS EVENING. THUNDERSTORM CHANCES INCREASE AT ALL TERMINALS ON MONDAY AND TUESDAY AS A SLOW MOVING AREA OF LOW PRESSURE REMAINS PARKED OFF THE CENTRAL CALIFORNIA COAST WITH DEEP MOISTURE IN PLACE ACROSS THE SIERRA AND WESTERN NEVADA. MYRICK && .REV WATCHES/WARNINGS/ADVISORIES... NV...NONE. CA...NONE. && $$ FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT... HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1042 PM EDT SUN AUG 18 2013 .SYNOPSIS... LOW PRESSURE WILL TRACK SOUTHEAST OF LONG ISLAND TONIGHT. A SURFACE TROUGH ACROSS THE AREA ON MONDAY WILL WEAKEN MONDAY NIGHT AND TUESDAY AS HIGH PRESSURE STARTS TO BUILD IN FROM THE WEST AND SOUTH. THIS HIGH PRESSURE CENTERED TO OUR SOUTH WILL GRADUALLY WEAKEN THROUGH THE MIDDLE OF THE WEEK. A COLD FRONT WILL MOVE THROUGH THE AREA LATE THU NIGHT OR FRI MORNING WITH HIGH PRESSURE RETURNING IN ITS WAKE. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... A WEAK LOW PRESSURE SYSTEM REMAINS WELL EAST OF THE DELMARVA COAST AND WILL CONTINUE TO TRACK NE OVERNIGHT. RAIN HAS MOVED OUT OF THE AREA AND TOOK OUT ALL POPS EXCEPT FOR A SLIGHT CHANCE MENTION OVER EASTERN LONG ISLAND AS THE RAIN IS STILL MOVING OUT IN THAT AREA. THE NEXT THING THAT WILL NEED WATCHING IS AN AREA OF CONVECTION CURRENTLY OVER SOUTHERN W VA...ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE. THE NAM/GFS AND HRRR ALL INDICATE THIS APPROACHES LATE TONIGHT...BUT KEEP ANY MEASURABLE PRECIP TO OUR W (THE HRRR ENDS AT 11Z WITH IT OVER ERN PA) CLOUDS WILL DECREASE OVERNIGHT BUT HOW MUCH REMAINS QUESTIONABLE DUE TO THE APPROACHING SHORTWAVE ENERGY/PRECIP. AS A RESULT...RADIATIONAL COOLING MAY BE MORE LIMITED THAN PREVIOUSLY THOUGHT. LOWS ARE EXPECTED TO RANGE MOSTLY FROM THE LOWER 50S TO LOWER 60S...A FEW DEGREES WARMER IN THE NEW YORK CITY METRO AREA. DID RAISE MIN TEMPS ON THIS UPDATE AS CLOUD COVER REMAINS OVER THE AREA. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/... FOR MONDAY...EXPECTING CONSIDERABLE MID AND UPPER LEVEL CLOUDS AHEAD OF THE NEXT SHORTWAVE. THIS WILL MITIGATE DAYTIME WARMTH BUT THE GREATER WESTERLY LOW LEVEL FLOW WILL ENABLE BETTER ADIABATIC MIXING UP TO AROUND 900MB. IT WILL BE WARMEST ACROSS THE URBAN AND VALLEY CORRIDORS AND A FEW DEGREES COOLER AT THE COAST WITH MORE ONSHORE FLOW. THE UPPER LEVEL JET MOVES ACROSS THE REGION WITH ITS ENTRANCE REGION MOVING ACROSS LATE IN THE DAY INTO THE EVENING. WE ARE NOT NEAR THE FAVORABLE RIGHT ENTRANCE REGION OF THIS JET BUT CONSIDERING THE STRONGER SHORTWAVE AND ADDITION OF DAYTIME INSTABILITY...A SHOWER OR THUNDERSTORM CANNOT BE RULED OUT. IN ADDITION...THE INDICATION OF DAYTIME SURFACE TROUGH DEVELOPMENT COULD MEAN THAT WINDS COULD BE MORE WEST OR NORTHWEST AWAY FROM THE COAST WITH MORE SOUTHERLY FLOW AT THE COAST WITH SEA BREEZE POTENTIAL...THEREBY INCREASING THE POTENTIAL FOR SURFACE CONVERGENCE. FOR MONDAY NIGHT...THE UPPER LEVEL JET AND SHORTWAVE AXIS EXIT SOUTHEAST OF THE REGION. THIS WILL ALLOW FOR HEIGHT RISES ALOFT AND SURFACE HIGH PRESSURE WILL START TO BUILD IN FROM THE SOUTH AND WEST. THIS WILL ALSO MARK A MODERATION OF THE AIRMASS TO ONE MORE TYPICAL OF SUMMER AS TEMPS ALOFT INCREASE SLIGHTLY WITH THE RIDGING. SO DESPITE THE LOWERING CLOUDS AND LIGHT WINDS...THE LOWS WILL ACTUALLY BE A FEW DEGREES WARMER THAN THE PREVIOUS NIGHT. FOR TUESDAY...A CONTINUED WARMING TREND WITH 850MB TEMPS INCREASING 1-2 DEGREES C FROM THE DAY BEFORE WITH THE ADDED SUPPORT OF CONTINUED SUBSIDENCE...ALLOWING FOR MORE SUNSHINE. WINDS WILL BE SIMILAR TO THE DAY BEFORE BUT A FEW KNOTS LIGHTER IN SPEED. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... LATEST MODELS/ENSEMBLES CONTINUE TO ADVERTISE A GRADUAL AMPLIFICATION OF THE PATTERN DURING THE MEDIUM RANGE PERIOD... WITH TROUGHS SETTLING OVER THE ERN PACIFIC AND CANADIAN MARITIMES/EXTREME WRN ATLC. AT THE SAME TIME A MEAN RIDGE SHOULD DRIFT SLOWLY EWD FROM THE PLAINS/SRN ROCKIES WHILE ANOTHER RIDGE SHOULD REMAIN CENTERED OFF THE SERN COAST TO THE N OF THE BAHAMAS. ALTHOUGH THERE IS GOOD AGREEMENT/CONTINUITY WITH THE FCST FOR LARGE SCALE FLOW...SPREAD WITH THE TIMING AND AMPLITUDE OF INDIVIDUAL SHRTWVS WITHIN THE FLOW FROM THE ERN PAC ACROSS SRN CANADA/NRN TIER CONUS PRESENTS PROBLEMS FOR DETERMINING THE EXACT POSITION OF THE MEAN SFC BOUNDARY EXPECTED TO SET UP FROM THE NRN PLAINS INTO THE MID ATLC. SUCH DETAILS ARE TYPICALLY NOT EASILY RESOLVED IN THE MEDIUM RANGE TIME FRAME SO HAVE LEANED TOWARDS WPC GUIDANCE WHICH CONSISTS OF A BLEND OF THE 06Z GEFS/00Z ECMWF MEANS WITH MINOR DETAIL ENHANCEMENTS. THIS SOLN PROVIDES BETTER CONTINUITY THAN MOST OPERATIONAL MODELS AT THIS TIME. WITH LEADING HGT FALLS CROSSING THE ERN HALF OF SRN CANADA DURING THE FIRST HALF OF THE PERIOD THE 00Z ECMWF STARTS LEANING TOWARD THE FASTER/AMPLIFIED SIDE OF THE SPREAD BY LATE THU-FRI...WHILE IN VARYING WAYS THE 00Z GFS/CMC BECOME FAIRLY AMPLIFIED WITH THEIR ERN NOAM TROUGH ALBEIT WITHIN THE ENSEMBLE SPREAD. THE PREFERRED ENSEMBLE MEANS TONE DOWN TROUGH AMPLITUDE AND SEWD PROGRESSION OF THE LEADING COLD FRONT SLIGHTLY. UPSTREAM DIFFS AT THE SFC BECOME PRONOUNCED BY FRI AS RECENT ECMWF RUNS HAVE BEEN TRYING TO BRING A WAVE INTO THE UPR MS VLY/UPR GRTLKS WHILE GFS RUNS KEEP MUCH HIGHER PRESSURES IN PLACE OVER THE REGION. THE 00Z UKMET HINTS AT AN ECMWF-TYPE WAVE BUT THE 00Z CMC AS WELL AS LATEST GEFS/ECMWF/CMC MEANS ARE NOT VERY ENTHUSIASTIC ABOUT SUCH A WAVE. ESPECIALLY GIVEN THE RELATIVELY FLAT NATURE OF THE MEAN FLOW ALONG THE US-CANADIAN BORDER AT THAT TIME...WOULD PREFER TO SEE MORE AGREEMENT FROM GUIDANCE BEFORE TRENDING TOWARD THE ECMWF SCENARIO. THEREFORE LOCALLY...THE CONTINUATION OF BENIGN WEATHER IS EXPECTED TO MOSTLY PREVAIL WITH MORE SUMMER LIKE TEMPERATURES DURING THE MIDDLE OF THE WEEK. A FEW LOCATIONS IN METRO NY/NJ MAY REACH THE 90 DEGREE MARK BOTH WED AND THU...WHICH WILL BE THE FIRST TIME IN A MONTH. HUMIDITY LEVELS WILL ALSO CREEP BACK UP WITH DEWPOINT TEMPERATURES IN THE MID TO UPPER 60S. HEAT INDICES ARE EXPECTED TO REMAIN BELOW 95 DEGREES. A PREFRONTAL TROUGH WILL SET UP W OF NYC ON THU. ISOLD SHOWERS/POSSIBLE A TSTM MAY BE TRIGGERED N AND W OF NYC...BUT HAVE KEPT THE FORECAST DRY AS PREDICTABILITY IS TOO LOW. AS THE COLD FRONT WHICH IS PROGGED TO MOVE THROUGH LATE THU NIGHT/FRI...THE CHC FOR SHOWERS/TSTMS WILL INCREASE ALTHOUGH HAVE KEPT SCHC POPS AHEAD OF AND WITH ITS PASSAGE DUE TO THE AFOREMENTIONED UNCERTAINTY. HAVE ALSO GONE WITH THE CONSENSUS NEXT WEEKEND AND KEPT THE FORECAST DRY. TEMPS WILL START OFF ABOVE NORMAL...THEN FALL BACK TO SEASONABLE LEVELS AT THE END OF THE WEEK. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... LOW PRESSURE CONTINUE TO TRACK WELL TO THE SOUTHEAST TONIGHT. WEAK HIGH PRESSURE RETURNS ON MONDAY VFR. LIGHT AND VARIABLE THIS EVENING...THEN BECOMING LIGHT WESTERLY TOWARDS DAYBREAK. FOR MONDAY...WSW WINDS INCREASING TO AROUND 10 KT ACROSS WESTERN TERMINALS...AND SW ACROSS COASTAL TERMINALS. SEABREEZE DEVELOPMENT LIKELY ACROSS KJFK/KISP/KBDR/KGON. LOW PROBABILITY OF SEABREEZE REACHING KLGA...AND NOT EXPECTED ELSEWHERE. BKN CIGS OF AROUND 10-15 KFT LIKELY...WITH SCT 4-6 KFT CU. OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY... .MONDAY NIGHT-WEDNESDAY...VFR. .THURS...CHC SUB-VFR AND TSTM. .FRI...VFR. && .MARINE... SUB SCA CONDITIONS WILL PREVAIL ACROSS THE WATERS THROUGH TUESDAY. THE PRESSURE GRADIENT WILL REMAIN WEAK ENOUGH TO LIMIT THE UPPER EXTENT OF WIND SPEED TO AROUND 15 KT AND SEAS ON THE OCEAN WILL STAY BETWEEN 2 AND 3 FT FOR MOST OF THE TIME. WAVEWATCH GUIDANCE SEEMED TO BE AGREEING PRETTY WELL WITH CURRENT BUOY OBS IN TERMS OF WAVE HEIGHT. THE WINDS AND SEAS ARE FORECAST TO REMAIN BLO SCA LEVELS THROUGH THE REST OF THE FORECAST PERIOD. && .HYDROLOGY... NO SIGNIFICANT WIDESPREAD RAIN IS EXPECTED. A FEW HUNDREDTHS OF AN INCH OF ADDITIONAL QPF IS EXPECTED THIS EVE MAINLY ON EASTERN LONG ISLAND AND SE CT. && .EQUIPMENT... THE NOAA ALL HAZARDS WEATHER RADIO TRANSMITTER IN NEW YORK CITY HAS BEEN DE-ACTIVATED UNTIL FURTHER NOTICE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...24/JM NEAR TERM...JM/LN SHORT TERM...JM LONG TERM...24 AVIATION...NV MARINE...24/JM HYDROLOGY...24/JM EQUIPMENT...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
941 PM EDT SUN AUG 18 2013 .SYNOPSIS... LOW PRESSURE WILL TRACK SOUTHEAST OF LONG ISLAND TONIGHT. A SURFACE TROUGH ACROSS THE AREA ON MONDAY WILL WEAKEN MONDAY NIGHT AND TUESDAY AS HIGH PRESSURE STARTS TO BUILD IN FROM THE WEST AND SOUTH. THIS HIGH PRESSURE CENTERED TO OUR SOUTH WILL GRADUALLY WEAKEN THROUGH THE MIDDLE OF THE WEEK. A COLD FRONT WILL MOVE THROUGH THE AREA LATE THU NIGHT OR FRI MORNING WITH HIGH PRESSURE RETURNING IN ITS WAKE. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... A WEAK LOW PRESSURE SYSTEM REMAINS WELL EAST OF THE DELMARVA COAST AND WILL CONTINUE TO TRACK NE OVERNIGHT. RAIN HAS MOVED OUT OF THE AREA AND TOOK OUT ALL POPS EXCEPT FOR A SLIGHT CHANCE MENTION OVER EASTERN LONG ISLAND AS THE RAIN IS STILL MOVING OUT IN THAT AREA. THE NEXT THING THAT WILL NEED WATCHING IS AN AREA OF CONVECTION CURRENTLY OVER SOUTHERN W VA...ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE. THE NAM/GFS AND HRRR ALL INDICATE THIS APPROACHES LATE TONIGHT...BUT KEEP ANY MEASURABLE PRECIP TO OUR W (THE HRRR ENDS AT 11Z WITH IT OVER ERN PA) CLOUDS WILL DECREASE OVERNIGHT BUT HOW MUCH REMAINS QUESTIONABLE DUE TO THE APPROACHING SHORTWAVE ENERGY/PRECIP. AS A RESULT...RADIATIONAL COOLING MAY BE MORE LIMITED THAN PREVIOUSLY THOUGHT. LOWS ARE EXPECTED TO RANGE MOSTLY FROM THE LOWER 50S TO LOWER 60S...A FEW DEGREES WARMER IN THE NEW YORK CITY METRO AREA. DID RAISE MIN TEMPS ON THIS UPDATE AS CLOUD COVER REMAINS OVER THE AREA. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/... FOR MONDAY...EXPECTING CONSIDERABLE MID AND UPPER LEVEL CLOUDS AHEAD OF THE NEXT SHORTWAVE. THIS WILL MITIGATE DAYTIME WARMTH BUT THE GREATER WESTERLY LOW LEVEL FLOW WILL ENABLE BETTER ADIABATIC MIXING UP TO AROUND 900MB. IT WILL BE WARMEST ACROSS THE URBAN AND VALLEY CORRIDORS AND A FEW DEGREES COOLER AT THE COAST WITH MORE ONSHORE FLOW. THE UPPER LEVEL JET MOVES ACROSS THE REGION WITH ITS ENTRANCE REGION MOVING ACROSS LATE IN THE DAY INTO THE EVENING. WE ARE NOT NEAR THE FAVORABLE RIGHT ENTRANCE REGION OF THIS JET BUT CONSIDERING THE STRONGER SHORTWAVE AND ADDITION OF DAYTIME INSTABILITY...A SHOWER OR THUNDERSTORM CANNOT BE RULED OUT. IN ADDITION...THE INDICATION OF DAYTIME SURFACE TROUGH DEVELOPMENT COULD MEAN THAT WINDS COULD BE MORE WEST OR NORTHWEST AWAY FROM THE COAST WITH MORE SOUTHERLY FLOW AT THE COAST WITH SEA BREEZE POTENTIAL...THEREBY INCREASING THE POTENTIAL FOR SURFACE CONVERGENCE. FOR MONDAY NIGHT...THE UPPER LEVEL JET AND SHORTWAVE AXIS EXIT SOUTHEAST OF THE REGION. THIS WILL ALLOW FOR HEIGHT RISES ALOFT AND SURFACE HIGH PRESSURE WILL START TO BUILD IN FROM THE SOUTH AND WEST. THIS WILL ALSO MARK A MODERATION OF THE AIRMASS TO ONE MORE TYPICAL OF SUMMER AS TEMPS ALOFT INCREASE SLIGHTLY WITH THE RIDGING. SO DESPITE THE LOWERING CLOUDS AND LIGHT WINDS...THE LOWS WILL ACTUALLY BE A FEW DEGREES WARMER THAN THE PREVIOUS NIGHT. FOR TUESDAY...A CONTINUED WARMING TREND WITH 850MB TEMPS INCREASING 1-2 DEGREES C FROM THE DAY BEFORE WITH THE ADDED SUPPORT OF CONTINUED SUBSIDENCE...ALLOWING FOR MORE SUNSHINE. WINDS WILL BE SIMILAR TO THE DAY BEFORE BUT A FEW KNOTS LIGHTER IN SPEED. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... LATEST MODELS/ENSEMBLES CONTINUE TO ADVERTISE A GRADUAL AMPLIFICATION OF THE PATTERN DURING THE MEDIUM RANGE PERIOD... WITH TROUGHS SETTLING OVER THE ERN PACIFIC AND CANADIAN MARITIMES/EXTREME WRN ATLC. AT THE SAME TIME A MEAN RIDGE SHOULD DRIFT SLOWLY EWD FROM THE PLAINS/SRN ROCKIES WHILE ANOTHER RIDGE SHOULD REMAIN CENTERED OFF THE SERN COAST TO THE N OF THE BAHAMAS. ALTHOUGH THERE IS GOOD AGREEMENT/CONTINUITY WITH THE FCST FOR LARGE SCALE FLOW...SPREAD WITH THE TIMING AND AMPLITUDE OF INDIVIDUAL SHRTWVS WITHIN THE FLOW FROM THE ERN PAC ACROSS SRN CANADA/NRN TIER CONUS PRESENTS PROBLEMS FOR DETERMINING THE EXACT POSITION OF THE MEAN SFC BOUNDARY EXPECTED TO SET UP FROM THE NRN PLAINS INTO THE MID ATLC. SUCH DETAILS ARE TYPICALLY NOT EASILY RESOLVED IN THE MEDIUM RANGE TIME FRAME SO HAVE LEANED TOWARDS WPC GUIDANCE WHICH CONSISTS OF A BLEND OF THE 06Z GEFS/00Z ECMWF MEANS WITH MINOR DETAIL ENHANCEMENTS. THIS SOLN PROVIDES BETTER CONTINUITY THAN MOST OPERATIONAL MODELS AT THIS TIME. WITH LEADING HGT FALLS CROSSING THE ERN HALF OF SRN CANADA DURING THE FIRST HALF OF THE PERIOD THE 00Z ECMWF STARTS LEANING TOWARD THE FASTER/AMPLIFIED SIDE OF THE SPREAD BY LATE THU-FRI...WHILE IN VARYING WAYS THE 00Z GFS/CMC BECOME FAIRLY AMPLIFIED WITH THEIR ERN NOAM TROUGH ALBEIT WITHIN THE ENSEMBLE SPREAD. THE PREFERRED ENSEMBLE MEANS TONE DOWN TROUGH AMPLITUDE AND SEWD PROGRESSION OF THE LEADING COLD FRONT SLIGHTLY. UPSTREAM DIFFS AT THE SFC BECOME PRONOUNCED BY FRI AS RECENT ECMWF RUNS HAVE BEEN TRYING TO BRING A WAVE INTO THE UPR MS VLY/UPR GRTLKS WHILE GFS RUNS KEEP MUCH HIGHER PRESSURES IN PLACE OVER THE REGION. THE 00Z UKMET HINTS AT AN ECMWF-TYPE WAVE BUT THE 00Z CMC AS WELL AS LATEST GEFS/ECMWF/CMC MEANS ARE NOT VERY ENTHUSIASTIC ABOUT SUCH A WAVE. ESPECIALLY GIVEN THE RELATIVELY FLAT NATURE OF THE MEAN FLOW ALONG THE US-CANADIAN BORDER AT THAT TIME...WOULD PREFER TO SEE MORE AGREEMENT FROM GUIDANCE BEFORE TRENDING TOWARD THE ECMWF SCENARIO. THEREFORE LOCALLY...THE CONTINUATION OF BENIGN WEATHER IS EXPECTED TO MOSTLY PREVAIL WITH MORE SUMMER LIKE TEMPERATURES DURING THE MIDDLE OF THE WEEK. A FEW LOCATIONS IN METRO NY/NJ MAY REACH THE 90 DEGREE MARK BOTH WED AND THU...WHICH WILL BE THE FIRST TIME IN A MONTH. HUMIDITY LEVELS WILL ALSO CREEP BACK UP WITH DEWPOINT TEMPERATURES IN THE MID TO UPPER 60S. HEAT INDICES ARE EXPECTED TO REMAIN BELOW 95 DEGREES. A PREFRONTAL TROUGH WILL SET UP W OF NYC ON THU. ISOLD SHOWERS/POSSIBLE A TSTM MAY BE TRIGGERED N AND W OF NYC...BUT HAVE KEPT THE FORECAST DRY AS PREDICTABILITY IS TOO LOW. AS THE COLD FRONT WHICH IS PROGGED TO MOVE THROUGH LATE THU NIGHT/FRI...THE CHC FOR SHOWERS/TSTMS WILL INCREASE ALTHOUGH HAVE KEPT SCHC POPS AHEAD OF AND WITH ITS PASSAGE DUE TO THE AFOREMENTIONED UNCERTAINTY. HAVE ALSO GONE WITH THE CONSENSUS NEXT WEEKEND AND KEPT THE FORECAST DRY. TEMPS WILL START OFF ABOVE NORMAL...THEN FALL BACK TO SEASONABLE LEVELS AT THE END OF THE WEEK. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... LOW PRESSURE PASSES TO THE SOUTH TONIGHT. WEAK HIGH PRESSURE RETURNS ON MONDAY. VFR THROUGH THE TAF PERIOD. LINGERING LIGHT SHOWERS COME TO AN END THIS EVENING. E/NE WINDS BECOME LIGHT AND VARIABLE THIS EVENING...THEN BECOMING LIGHT WESTERLY AFTER 06Z. FOR MONDAY...WSW TO SW WINDS INCREASING TO AROUND 10 KT. BKN CIGS OF AROUND 10-15 KFT LIKELY...WITH SCT 4-6 KFT CU. SEABREEZE DEVELOPMENT LIKELY ACROSS KJFK/KISP/KBDR/KGON. LOW PROBABILITY OF SEABREEZE REACHING KLGA...AND NOT EXPECTED ELSEWHERE. OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY... .MONDAY NIGHT-WEDNESDAY...VFR. .THURS...CHC SUB-VFR AND TSTM. .FRI...VFR. && .MARINE... SUB SCA CONDITIONS WILL PREVAIL ACROSS THE WATERS THROUGH TUESDAY. THE PRESSURE GRADIENT WILL REMAIN WEAK ENOUGH TO LIMIT THE UPPER EXTENT OF WIND SPEED TO AROUND 15 KT AND SEAS ON THE OCEAN WILL STAY BETWEEN 2 AND 3 FT FOR MOST OF THE TIME. WAVEWATCH GUIDANCE SEEMED TO BE AGREEING PRETTY WELL WITH CURRENT BUOY OBS IN TERMS OF WAVE HEIGHT. THE WINDS AND SEAS ARE FORECAST TO REMAIN BLO SCA LEVELS THROUGH THE REST OF THE FORECAST PERIOD. && .HYDROLOGY... NO SIGNIFICANT WIDESPREAD RAIN IS EXPECTED. A FEW HUNDREDTHS OF AN INCH OF ADDITIONAL QPF IS EXPECTED THIS EVE MAINLY ON EASTERN LONG ISLAND AND SE CT. && .EQUIPMENT... THE NOAA ALL HAZARDS WEATHER RADIO TRANSMITTER IN NEW YORK CITY HAS BEEN DE-ACTIVATED UNTIL FURTHER NOTICE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...24/JM NEAR TERM...JM/LN SHORT TERM...JM LONG TERM...24 AVIATION...JC MARINE...24/JM HYDROLOGY...24/JM EQUIPMENT...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
759 PM EDT SUN AUG 18 2013 .SYNOPSIS... LOW PRESSURE WILL TRACK SOUTHEAST OF LONG ISLAND TONIGHT. A SURFACE TROUGH ACROSS THE AREA ON MONDAY WILL WEAKEN MONDAY NIGHT AND TUESDAY AS HIGH PRESSURE STARTS TO BUILD IN FROM THE WEST AND SOUTH. THIS HIGH PRESSURE CENTERED TO OUR SOUTH WILL GRADUALLY WEAKEN THROUGH THE MIDDLE OF THE WEEK. A COLD FRONT WILL MOVE THROUGH THE AREA LATE THU NIGHT OR FRI MORNING WITH HIGH PRESSURE RETURNING IN ITS WAKE. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... A WEAK LOW OFF THE DELMARVA COAST WILL CONTINUE TO TRACK NORTHEAST WHILE DEEPENING A BIT TONIGHT. RAIN IS MOVING OUT QUICKER THAN EXPECTED...AND IS MAINLY CONFINED TO LONG ISLAND AND SE CT...SO HAVE ADJUSTED THE POP FORECAST ACCORDINGLY. RAIN SHOULD BE COMPLETELY OFFSHORE BY 3Z. THE NEXT THING THAT WILL BEAR WATCHING IS AN AREA OF CONVECTION CURRENTLY OVER SOUTHERN W VA...ASSOCIATED WITH AN UPPER LEVEL SHORTWAVE. THE NAM/GFS AND HRRR ALL INDICATE THIS APPROACHES LATE TONIGHT...BUT KEEP ANY MEASURABLE PRECIP TO OUR W (THE HRRR ENDS AT 11Z WITH IT OVER ERN PA) CLOUDS WILL DECREASE OVERNIGHT BUT HOW MUCH REMAINS QUESTIONABLE DUE TO THE APPROACHING SHORTWAVE ENERGY/PRECIP. AS A RESULT...RADIATIONAL COOLING MAY BE MORE LIMITED THAN PREVIOUSLY THOUGHT. LOWS ARE EXPECTED TO RANGE MOSTLY FROM THE LOWER 50S TO LOWER 60S...A FEW DEGREES WARMER IN THE NEW YORK CITY METRO AREA...ALTHOUGH MINS MAY NEED TO BE RAISED A FEW DEGREES IF THERE ENDS UP BEING MORE CLOUD COVER. WILL MONITOR AND REEVALUATE WITH THE NEXT UPDATE. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/... FOR MONDAY...EXPECTING CONSIDERABLE MID AND UPPER LEVEL CLOUDS AHEAD OF THE NEXT SHORTWAVE. THIS WILL MITIGATE DAYTIME WARMTH BUT THE GREATER WESTERLY LOW LEVEL FLOW WILL ENABLE BETTER ADIABATIC MIXING UP TO AROUND 900MB. IT WILL BE WARMEST ACROSS THE URBAN AND VALLEY CORRIDORS AND A FEW DEGREES COOLER AT THE COAST WITH MORE ONSHORE FLOW. THE UPPER LEVEL JET MOVES ACROSS THE REGION WITH ITS ENTRANCE REGION MOVING ACROSS LATE IN THE DAY INTO THE EVENING. WE ARE NOT NEAR THE FAVORABLE RIGHT ENTRANCE REGION OF THIS JET BUT CONSIDERING THE STRONGER SHORTWAVE AND ADDITION OF DAYTIME INSTABILITY...A SHOWER OR THUNDERSTORM CANNOT BE RULED OUT. IN ADDITION...THE INDICATION OF DAYTIME SURFACE TROUGH DEVELOPMENT COULD MEAN THAT WINDS COULD BE MORE WEST OR NORTHWEST AWAY FROM THE COAST WITH MORE SOUTHERLY FLOW AT THE COAST WITH SEA BREEZE POTENTIAL...THEREBY INCREASING THE POTENTIAL FOR SURFACE CONVERGENCE. FOR MONDAY NIGHT...THE UPPER LEVEL JET AND SHORTWAVE AXIS EXIT SOUTHEAST OF THE REGION. THIS WILL ALLOW FOR HEIGHT RISES ALOFT AND SURFACE HIGH PRESSURE WILL START TO BUILD IN FROM THE SOUTH AND WEST. THIS WILL ALSO MARK A MODERATION OF THE AIRMASS TO ONE MORE TYPICAL OF SUMMER AS TEMPS ALOFT INCREASE SLIGHTLY WITH THE RIDGING. SO DESPITE THE LOWERING CLOUDS AND LIGHT WINDS...THE LOWS WILL ACTUALLY BE A FEW DEGREES WARMER THAN THE PREVIOUS NIGHT. FOR TUESDAY...A CONTINUED WARMING TREND WITH 850MB TEMPS INCREASING 1-2 DEGREES C FROM THE DAY BEFORE WITH THE ADDED SUPPORT OF CONTINUED SUBSIDENCE...ALLOWING FOR MORE SUNSHINE. WINDS WILL BE SIMILAR TO THE DAY BEFORE BUT A FEW KNOTS LIGHTER IN SPEED. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... LATEST MODELS/ENSEMBLES CONTINUE TO ADVERTISE A GRADUAL AMPLIFICATION OF THE PATTERN DURING THE MEDIUM RANGE PERIOD... WITH TROUGHS SETTLING OVER THE ERN PACIFIC AND CANADIAN MARITIMES/EXTREME WRN ATLC. AT THE SAME TIME A MEAN RIDGE SHOULD DRIFT SLOWLY EWD FROM THE PLAINS/SRN ROCKIES WHILE ANOTHER RIDGE SHOULD REMAIN CENTERED OFF THE SERN COAST TO THE N OF THE BAHAMAS. ALTHOUGH THERE IS GOOD AGREEMENT/CONTINUITY WITH THE FCST FOR LARGE SCALE FLOW...SPREAD WITH THE TIMING AND AMPLITUDE OF INDIVIDUAL SHRTWVS WITHIN THE FLOW FROM THE ERN PAC ACROSS SRN CANADA/NRN TIER CONUS PRESENTS PROBLEMS FOR DETERMINING THE EXACT POSITION OF THE MEAN SFC BOUNDARY EXPECTED TO SET UP FROM THE NRN PLAINS INTO THE MID ATLC. SUCH DETAILS ARE TYPICALLY NOT EASILY RESOLVED IN THE MEDIUM RANGE TIME FRAME SO HAVE LEANED TOWARDS WPC GUIDANCE WHICH CONSISTS OF A BLEND OF THE 06Z GEFS/00Z ECMWF MEANS WITH MINOR DETAIL ENHANCEMENTS. THIS SOLN PROVIDES BETTER CONTINUITY THAN MOST OPERATIONAL MODELS AT THIS TIME. WITH LEADING HGT FALLS CROSSING THE ERN HALF OF SRN CANADA DURING THE FIRST HALF OF THE PERIOD THE 00Z ECMWF STARTS LEANING TOWARD THE FASTER/AMPLIFIED SIDE OF THE SPREAD BY LATE THU-FRI...WHILE IN VARYING WAYS THE 00Z GFS/CMC BECOME FAIRLY AMPLIFIED WITH THEIR ERN NOAM TROUGH ALBEIT WITHIN THE ENSEMBLE SPREAD. THE PREFERRED ENSEMBLE MEANS TONE DOWN TROUGH AMPLITUDE AND SEWD PROGRESSION OF THE LEADING COLD FRONT SLIGHTLY. UPSTREAM DIFFS AT THE SFC BECOME PRONOUNCED BY FRI AS RECENT ECMWF RUNS HAVE BEEN TRYING TO BRING A WAVE INTO THE UPR MS VLY/UPR GRTLKS WHILE GFS RUNS KEEP MUCH HIGHER PRESSURES IN PLACE OVER THE REGION. THE 00Z UKMET HINTS AT AN ECMWF-TYPE WAVE BUT THE 00Z CMC AS WELL AS LATEST GEFS/ECMWF/CMC MEANS ARE NOT VERY ENTHUSIASTIC ABOUT SUCH A WAVE. ESPECIALLY GIVEN THE RELATIVELY FLAT NATURE OF THE MEAN FLOW ALONG THE US-CANADIAN BORDER AT THAT TIME...WOULD PREFER TO SEE MORE AGREEMENT FROM GUIDANCE BEFORE TRENDING TOWARD THE ECMWF SCENARIO. THEREFORE LOCALLY...THE CONTINUATION OF BENIGN WEATHER IS EXPECTED TO MOSTLY PREVAIL WITH MORE SUMMER LIKE TEMPERATURES DURING THE MIDDLE OF THE WEEK. A FEW LOCATIONS IN METRO NY/NJ MAY REACH THE 90 DEGREE MARK BOTH WED AND THU...WHICH WILL BE THE FIRST TIME IN A MONTH. HUMIDITY LEVELS WILL ALSO CREEP BACK UP WITH DEWPOINT TEMPERATURES IN THE MID TO UPPER 60S. HEAT INDICES ARE EXPECTED TO REMAIN BELOW 95 DEGREES. A PREFRONTAL TROUGH WILL SET UP W OF NYC ON THU. ISOLD SHOWERS/POSSIBLE A TSTM MAY BE TRIGGERED N AND W OF NYC...BUT HAVE KEPT THE FORECAST DRY AS PREDICTABILITY IS TOO LOW. AS THE COLD FRONT WHICH IS PROGGED TO MOVE THROUGH LATE THU NIGHT/FRI...THE CHC FOR SHOWERS/TSTMS WILL INCREASE ALTHOUGH HAVE KEPT SCHC POPS AHEAD OF AND WITH ITS PASSAGE DUE TO THE AFOREMENTIONED UNCERTAINTY. HAVE ALSO GONE WITH THE CONSENSUS NEXT WEEKEND AND KEPT THE FORECAST DRY. TEMPS WILL START OFF ABOVE NORMAL...THEN FALL BACK TO SEASONABLE LEVELS AT THE END OF THE WEEK. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... LOW PRESSURE PASSES TO THE SOUTH TONIGHT. WEAK HIGH PRESSURE RETURNS ON MONDAY. VFR THROUGH THE TAF PERIOD. LINGERING LIGHT SHOWERS COME TO AN END THIS EVENING. E/NE WINDS BECOME LIGHT AND VARIABLE THIS EVENING...THEN BECOMING LIGHT WESTERLY AFTER 06Z. FOR MONDAY...WSW TO SW WINDS INCREASING TO AROUND 10 KT. BKN CIGS OF AROUND 10-15 KFT LIKELY...WITH SCT 4-6 KFT CU. SEABREEZE DEVELOPMENT LIKELY ACROSS KJFK/KISP/KBDR/KGON. LOW PROBABILITY OF SEABREEZE REACHING KLGA...AND NOT EXPECTED ELSEWHERE. OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY... .MONDAY NIGHT-WEDNESDAY...VFR. .THURS...CHC SUB-VFR AND TSTM. .FRI...VFR. && .MARINE... SUB SCA CONDITIONS WILL PREVAIL ACROSS THE WATERS THROUGH TUESDAY. THE PRESSURE GRADIENT WILL REMAIN WEAK ENOUGH TO LIMIT THE UPPER EXTENT OF WIND SPEED TO AROUND 15 KT AND SEAS ON THE OCEAN WILL STAY BETWEEN 2 AND 3 FT FOR MOST OF THE TIME. WAVEWATCH GUIDANCE SEEMED TO BE AGREEING PRETTY WELL WITH CURRENT BUOY OBS IN TERMS OF WAVE HEIGHT. THE WINDS AND SEAS ARE FORECAST TO REMAIN BLO SCA LEVELS THROUGH THE REST OF THE FORECAST PERIOD. && .HYDROLOGY... NO SIGNIFICANT WIDESPREAD RAIN IS EXPECTED. A FEW HUNDREDTHS OF AN INCH OF ADDITIONAL QPF IS EXPECTED THIS EVE MAINLY ON EASTERN LONG ISLAND AND SE CT. && .EQUIPMENT... THE NOAA ALL HAZARDS WEATHER RADIO TRANSMITTER IN NEW YORK CITY HAS BEEN DE-ACTIVATED UNTIL FURTHER NOTICE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
351 PM EDT SAT AUG 17 2013 .DISCUSSION... THROUGH TONIGHT...EAST COAST SEA BREEZE WILL SPARK SCATTERED STORMS OVER THE INTERIOR AND VOLUSIA NEXT FEW HOURS...THEN STORMS SHOULD PUSH DIMINISH SHORTLY AFTER SUNSET. SUBSIDENCE ASSOCD WITH SEA BREEZE CIRCULATION WILL KEEP COASTAL SECTIONS FROM BREVARD TO MARTIN COUNTIES DRY THE REST OF THE AFTERNOON. THE LOW LEVEL RIDGE WILL LIFT NORTH OF THE AREA TONIGHT AND PRODUCE A SYNOPTIC E/SE FLOW OF 10-14 KNOTS. THIS SHOULD BE SUFFICIENT FLOW COMBINED WITH HIGH MOISTURE TO PRODUCE A FEW ATLC SHOWERS THAT COULD REACH THE COAST OVERNIGHT SO HAVE DRAWN A 20 POP ALONG THE COAST. A WARM NIGHT WITH LOWS IN THE MID TO UPPER 70S...EVEN SOME LOWER 80S BEACHSIDE. SUN-MON...(PREVIOUS) CENTRAL FL WILL UNDERGO A SHIFT TO A DRIER WX PATTERN AS THE LIFTING H30-H20 JET OVER THE APPALACHIANS ALLOWS THE ATLC RIDGE AXIS TO REPOSITION ITSELF OVER THE DEEP SOUTH BY DAYBREAK SUN. POSITION WILL BE STABLE AS UPSTREAM JET ENERGY OVER THE SRN TIER STATES IS QUITE WEAK AND WILL NOT BE ABLE DO DISLODGE IT. POSITION OF THE RIDGE AXIS WILL GENERATE A DEEP AND STEADY E/SE FLOW ACRS CENTRAL FL...A PATTERN THAT FAVORS THE WEST PENINSULA FOR DIURNAL CONVECTION RATHER THAN THE EAST DUE LARGELY TO THE EARLY FORMATION AND DIFFUSE NATURE OF THE RESULTING EAST COAST SEA BREEZE. FURTHERMORE...LATEST RUC ANALYSIS SHOWS A NOTEWORTHY DROP IN DEEP LYR RH APPROACHING THE SRN BAHAMAS THAT WILL WORK ITS WAY INTO THE FL PENINSULA TO START THE UPCOMING WEEK. GFS MODEL SOUNDINGS CONFIRM THE ANTICIPATED DRY TREND...DROPPING PWAT VALUES FROM ARND 2.0" AT 12Z SUN TO ARND 1.7" BY 12Z MON. EVEN THE HIGHER PWAT VALUES ARE SUN ARE SOMEWHAT DECEIVING AS GFS INDICATES THE MOISTURE WILL BE EVENLY DISTRIBUTED THRU THE COLUMN... NOT CONCENTRATED IN THE LOW/MID LVLS WHERE IT WOULD SUPPORT HIGHER AMOUNTS OF DIURNAL CONVECTION. STORM POTENTIAL WILL REMAIN LOW AS THE ERLY FLOW TAPS AN AIRMASS WITH NEGLIGIBLE MID LVL VORTICITY OR OF UPR LVL JET SUPPORT. THERMODYNAMIC PROFILE MAY PROVIDE SOME PUNCH AS UPSTREAM H50 TEMPS DROP INTO THE -7C TO -8C RANGE AND H85-H50 LAPSE RATES STEEPEN TO 6.0-6.5C/KM. HOWEVER...ANY STRONG ACTIVITY WOULD TEND TO FORM W OF THE FL TURNPIKE AS THE DEEP ERLY FLOW WILL PUSH THE SEA BREEZE RAPIDLY INLAND. PRECIP COVERAGE AOB 40PCT WITH HIGHEST COVERAGE OVER THE INTERIOR SUN AFTN TO GIVE A NOD TO THE AFOREMENTIONED HIGHER PWAT VALUES. ONSHORE FLOW WILL KEEP MAX TEMPS IN THE U80S/L90 ALONG THE COAST... INTERIOR WARMING TO THE L/M90S. MIN TEMPS L/M70S. TUE-FRI... LITTLE CHANGE TO THE CURRENT PHILOSOPHY...STABLE POSITION OF THE ATLC RIDGE AXIS WILL MAINTAIN A DEEP ERLY FLOW ACRS CENTRAL FL FOR MUCH OF THE WEEK THAT WILL FOCUS DIURNAL CONVECTION OVER THE W PENINSULA. POPS 30-40PCT...HIGHER OVER THE INTERIOR DUE TO THE EARLY FORMATION OF THE EAST COAST SEA BREEZE. MAX TEMPS WITHIN A DEG OR TWO OF CLIMO AVG...MIN TEMPS 3-5F ABV AVG DUE TO THE PERSISTENT ONSHORE FLOW. && .AVIATION... SCT TSRA AT LEE/MCO/SFB THROUGH 23Z. ISOLD SHRA MAY APPROACH COASTAL TAFS OVERNIGHT BUT COVERAGE DOES NOT WARRANT MENTION IN TAFS. COULD SEE TEMPO MVFR CIGS 13Z-16Z SUN ALONG WITH ISOLD SHRA AS DIFFUSE SEA BREEZE DEVELOPS...FOLLOWED BY SCATTERED SHRA/TSRA FOCUSED ON THE INTERIOR AFT 16Z. && .MARINE... ATLC RIDGE WILL REPOSITION ITSELF NORTH OF THE WATERS TONIGHT WHERE IT WILL REMAIN THRU MIDWEEK. THIS RIDGE POSITION WILL GENERATE A STEADY STATE GENTLE TO MODERATE E/SE BREEZE. THESE WINDS WILL PUSH A SMALL ERLY SWELL INTO THE LCL ATLC...BUILDING SEAS UP TO 4 FT OFFSHORE SUN NIGHT AND MONDAY...3 FT NEARSHORE. SEAS WILL GRADUALLY SUBSIDE TUE-WED AS THE SWELL DAMPENS. ISOLD SHRA/TSRA THRU THE PD. && .PRELIMINARY POINT TEMPS/POPS... DAB 76 89 77 90 / 20 40 20 30 MCO 76 93 75 93 / 20 40 10 30 MLB 78 90 78 91 / 20 30 20 30 VRB 77 91 76 90 / 20 20 20 30 LEE 76 94 76 94 / 20 50 20 40 SFB 77 93 76 93 / 20 40 10 30 ORL 77 93 77 93 / 20 40 10 30 FPR 76 90 76 90 / 20 20 20 30 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ PUBLIC/MARINE/FIRE WX/AVIATION...KELLY IMPACT WX/RADAR...WEITLICH
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
320 PM EDT Sat Aug 17 2013 .NEAR TERM [This Evening and Tonight]... A broken band of heavy rain showers and even a few thunderstorms continues to slowly shift east with time this afternoon across the forecast area (and our Florida zones in particular). The stronger convective cells appear to be situated along a composite outflow boundary / quasi-stationary front, with trailing light-moderate stratiform rain behind that (encompassing much of the western half of our forecast area). Therefore, high PoPs were maintained through the evening hours, particularly in the western two-thirds of our area. The high-resolution guidance including recent runs of the HRRR and our local TAE-WRF appears to be doing a poor job representing ongoing conditions. They dissipate the convection far too fast and have generally dry conditions advertised over our area around 19-20 UTC. Therefore, we expect that the ongoing rain and storms will linger for at least another few hours. The guidance (including global models) indicates that the rain and storms will consolidate back to the west later this evening and tonight. Therefore, the Flash Flood Watch was kept as is - which expires for our GA and eastern FL zones at 03 UTC, with much of the heavy rainfall after that time expected west of those areas. This will have to be closely monitored this evening, though. Given the environment (high PWATs, efficient rain processes), the threat of flash flooding continues across the area wherever heavier rain bands can set up. && .SHORT TERM [Sunday through Monday Night]... The quasi-stationary front may begin to slowly shift a bit further west on Sunday and lose its character as a low-level ridge builds into the Southeast from the Atlantic Ocean. Therefore, there should be less of a large-scale focusing mechanism for convection tomorrow (or it should be situated just north and west of our area). However, guidance still shows relatively high PoPs with continued high PWAT environment and southerly low-level flow. Therefore, we maintained likely PoPs over much of the area. A similar story exists for Monday, although with slightly more uncertainty we opted for high chance (50%) PoPs instead - but it could end up being another high coverage day for rain. Daytime temperatures should continue to be a little cooler than normal. && .LONG TERM [Tuesday through Saturday]... Southeast low-level flow gradually backs to more of an easterly direction as an upper level ridge builds into the region. This should equate to more suppressed convective activity with time, and overall PoPs show a decreasing trend through the extended forecast. However, there should still be daily thunderstorm chances. Temperatures will be closer to normal, perhaps warming to slightly above normal by later in the week. && .AVIATION [through 18 UTC Sunday]... Low CIGS and showers with embedded convection will prevail with MVFR-IFR conditions expected to continue this evening at ECP, DHN, and ABY and develop later overnight and tomorrow at TLH and VLD. Brief periods of LIFR CIGS and vsbys are expected in the heaviest bouts of rain. && .MARINE... With some breezy southeast winds being observed over the western waters at the moment (peak winds to near 20 knots), we have inserted a SCEC headline through tonight west of AAF. The winds will be slightly weaker in the eastern half of our coastal zones, but could still approach 15 knots at times. Winds and seas will lessen somewhat tomorrow morning, followed by a stretch of easterly flow with winds around 10 knots and seas 3 feet or less. && .FIRE WEATHER... Abundant moisture and rainfall will prevent red flag conditions from being met well into next week. && .HYDROLOGY... Widespread rain with some heavier bands continues this afternoon across much of the area. A lot of the rain over the western half of our area has been due to a band of heavier rain showers and a few thunderstorms. This band has been producing rain rates of up to 2-3 inches per hour, but has been showing steady eastward progression. Therefore, flash flooding issues have been isolated (so far) to urban areas around Panama City. The rain and storms should continue into the evening - possibly affecting areas further to the east - but then will eventually re-consolidate back to the west after midnight and into tomorrow. Given the widespread nature of the moderate to heavy rainfall, many river systems around the area should see notable rises and increased flows, except for perhaps the far southeast part of our area in Taylor, Lafayette, and Dixie counties. The rivers, as of a week ago, were running at lower levels than what we had seen for most of July, so it has taken a considerable amount of rain to move some to even a bankfull status. Flooding issues will be determined by the location of the heaviest rainfall over the next 1-2 days, although a few rivers that may be particularly at risk include: Choctawhatchee, Shoal, Apalachicola. The most up to date, specific river forecast information can be found on the AHPS web page at: http:/water.weather.gov/ahps2/index.php?wfo=tae. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 72 90 73 91 73 / 60 60 30 50 30 Panama City 76 87 76 88 76 / 60 60 40 50 30 Dothan 71 86 72 89 72 / 70 70 30 50 30 Albany 71 88 72 90 72 / 70 60 30 50 30 Valdosta 71 90 72 91 72 / 60 50 30 50 30 Cross City 73 90 72 91 72 / 40 50 40 40 30 Apalachicola 78 87 77 86 77 / 50 50 40 50 30 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...FLASH FLOOD WATCH until 11 PM EDT this evening for all zones east of the Apalachicola River. FLASH FLOOD WATCH through Sunday evening for all zones west of the Apalachicola River. GA...FLASH FLOOD WATCH until 11 PM EDT this evening for all zones. AL...FLASH FLOOD WATCH through Sunday evening for all zones. GM...None. && $$ Lamers/Moore
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
541 AM EDT Sat Aug 17 2013 ...HEAVY RAINFALL AND FLOODING CONCERNS EXPECTED AGAIN TODAY... .NEAR TERM [Thru TODAY]... We continue in a very wet and unsettled pattern. During the overnight hours, shortwave energy moving from the Cntrl/Srn Gulf of Mex has energized another band of deep tropical moisture (PWATS 2.1-2.2 inches) with training cells and interacted with a stalled front producing moderate to locally heavy rains across portions of the local area, especially the Panhandle. This aggravated the flooding situation which necessitated the issuance of a flood warning for Jackson and Washington counties. RAP soundings imply that low level steering flow was switching from SW to more sly feeding more of this moisture Nwd into our AL/GA counties near the front yielding rain rates of up to 2-3 inches per hour. By 3 AM EDT, strong to severe storms began developing across the nearshore waters and this will soon move over coastal counties. All this reflected well in HRRR. The large scale pattern continues to amplify with little change in last 12 hrs providing all the ingredients necessary today for a continued widespread heavy rain event further aggravating the flooding situation. Aloft, ridge over Wrn 1/3d and deep trough over Ern 2/3rd of Conus with axis down MS Valley. A deep 580DM low will centered over MO/TN border with a trough axis extending into the northwestern Gulf of Mex. A potent vortmax over AR/TN border with 90kt upper jet round the base of the trough placing the area in the favorable right entrance region. Several small shortwaves riding down base of trough nudging it ewd. All this increasing upper lift/diffluence over mainly WRN CWA. At the same time, weal upper ridging exists over Srn FL and a low/tropical wave was located in the SW Gulf on Mex (NW of Campeche). The combination of these features has allowed for sfc-H4 SW unidirectional flow providing a deep conveyor belt of tropical moisture spreading Newd across our local area. At the surface, front remains largely stalled from Srn Walton county Nwwd to along I-10 into SE GA yielding SWLY flow. However the combination of diurnal heating plus building H5 ridging across the Wrn Atlc and FL Peninsula should lift front Nwd thru the day placing more of area in warm sector. Convergence along this boundary should continue to serve as the focus for low level lift and where heaviest rains should occur (AL/GA). Model soundings show area PWATS in excess of 2 inches. Flash flooding will remain a serious concern as activity continues to train over areas which have already received significant rainfall. As the Gulf system moves further Wwd, guidance places the highest QPF and highest PoPs over the NW third of our forecast area. With many of these areas already saturated from a very wet summer, flash flooding will continue to be closely monitored. Thus the flash flood watch remains in effect for the entire area but Ern sections should be dropped this aftn. Will have categorical PoPs for most of the area with temperatures well below normal. See the hydrology section of this product for more details on the potential. As far as strong to severe storms, the existence of a very moist boundary layer and weak lapse rates argue against these storms, however with upper trough/jet/vort, cant discount wet microbursts with gusty to damaging winds best bet. SPC keeps us in 5% severe prob. Will go with CAT POPS west half and likely POPS east half with heavy rain in grids. Under cloudy and rain conditions, Max temps to remain well below normal, from around 80 SE AL to mid to upper 80s SE Big Bend. && .SHORT TERM [Tonight Through Monday]... As the Gulf system continues to shift Wwd into Wrn Gulf, expect corridor of heaviest rain progressively sliding west and out of our forecast area as Atlc ridge progressively builds NWWD thru period. However, the continued influence of the trough along the MS Valley (even thought its deamplifying) and now SW-NE oriented quasi-stnry front should combine for sct-likely POPs thru the period. For tonight, the deep layer conveyor belt will diminish as dry air spreads into Srn periphery of upper low but FL Panhandle and SE AL will remain in a favorable position to receive additional rain, possibly moderate to heavy, and thus lingering flooding concerns. By Sun, the upper low will lift Newd towards OH River Valley but trough and front will linger while the Gulf system should be far enough west (S TX or Mex) for little impact. However, latest guidance indicates that a piece of this feature will shear Nwd strengthening H85 flow and keeping moisture in at least our Wrn CWA even with the Atlc subtropical ridge building Nwwd into our area. By Mon, upper ridge over Wrn Atlc will expand into local area while front has moved further Nwd and weakened. We will return to a more seasonal pattern of mainly aftn/eve sct seabreeze driven convection as max temps return to near climo. Will go with 60-40% NW-SE POPs tonight, 60-50% on Sun and 50-30% N-S on Mon. Lows tonight around 70. Highs Sun Mid 80s NW to around 90 SE rising on Mon to upper 80s NW to lower 90s SE. && .LONG TERM [Monday Night through Friday]... Upper trough over the Lower Mississippi Valley is forecast to linger through the first half of next week keeping a moist and unstable airmass in place over the tri-state area. This will keep PoPs relatively high through at least Tuesday. By later in the week, there is more uncertainty in the guidance as to how much ridging will build back over the region, with the ECMWF keeping the upper trough in tact and the GFS indicating a stronger ridge. Being well into the extended, will keep conditions close to climo as a compromise. && .AVIATION... [Through 06z Sunday] Low cigs and showers with embedded convection will prevail with MVFR to IFR conditions expected. && .MARINE... Winds and seas will be on the increase through the weekend especially around any convection and especially over the western waters, as a trough of low pressure lingers to the north and west. However conditions should remain below exercise caution levels through Sunday. Winds and seas will diminish early next week. && .FIRE WEATHER... Abundant moisture and rainfall will prevent red flag conditions from being met well into next week. && .HYDROLOGY... Up until this morning, except for the FL Panhandle, showers have been progressive enough and not training which has kept the flood threat low. However, this should change today as the heaviest rains of this wet period are expected with widespread average rainfall amounts of 3 to 5 inches still anticipated mainly Wrn areas. Isolated higher totals are expected, possibly upward of 5 to 8 inches in some locations. River flooding will become an increasing concern by late today and into next week, especially depending on where the heaviest rainfall ends up occurring. The current thinking is that much of the heaviest rains will occur in the lower half of the basins. Thus, if the latest forecast holds, the Choctawhatchee Basin from Geneva through Bruce would easily return to minor flood stage late in the weekend with the potential for moderate flooding from Caryville southward to Bruce early next week. The Chipola has some capacity for heavy rainfall, but if rainfall amounts trend higher than expected, minor flooding would be a possibility at Marianna and Altha early next week. Into Southeast Alabama, soils are especially saturated and area creeks and stream will quickly respond to any significant rainfall. Minor flooding along the Choctawhatchee and Pea Rivers could occur quickly in this scenario late this weekend. In Southern Georgia and the Florida Big Bend, current projections move the Apalachicola, Flint, and Ochlockonee River systems to near flood stage with anticipated rainfall, though heavier amounts would easily lead to minor flooding, especially in the lower portions of these basins where heavier rains were received in July. Lighter rainfall amounts are anticipated further east into the Withlacoochee and Suwannee River basins and the current anticipation is for these rivers to remain below flood stage into next week. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 84 71 91 74 91 / 80 60 60 50 50 Panama City 83 75 88 77 86 / 90 60 60 50 50 Dothan 81 70 86 71 88 / 90 60 60 40 50 Albany 82 71 88 73 90 / 90 60 60 30 50 Valdosta 85 70 91 73 91 / 70 60 50 40 50 Cross City 88 73 91 72 91 / 50 40 50 40 50 Apalachicola 85 78 87 79 87 / 80 60 60 50 50 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...FLASH FLOOD WATCH through this evening for Coastal Dixie- Coastal Franklin-Coastal Jefferson-Coastal Taylor-Coastal Wakulla-Gadsden-Inland Dixie-Inland Franklin-Inland Jefferson-Inland Taylor-Inland Wakulla-Lafayette-Leon- Liberty-Madison. FLASH FLOOD WATCH through Sunday evening for Calhoun-Central Walton-Coastal Bay-Coastal Gulf-Holmes-Inland Bay-Inland Gulf-Inland Walton-Jackson-South Walton-Washington. GA...FLASH FLOOD WATCH through this evening for Baker-Ben Hill- Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur- Dougherty-Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller- Mitchell-Quitman-Randolph-Seminole-Terrell-Thomas-Tift- Turner-Worth. AL...FLASH FLOOD WATCH through Sunday evening for Coffee-Dale- Geneva-Henry-Houston. GM...None. && $$ Hydrology...Block/Godsey LONG TERM...Camp AVIATION/FIRE WX...DVD REST OF DISCUSSION...BLOCK
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
530 AM EDT SAT AUG 17 2013 .SYNOPSIS... 08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWS AN AMPLIFIED UPPER LEVEL PATTERN IN PLACE OVER THE EASTERN HALF OF THE NATION...HIGHLIGHTED BY A DEEP TROUGH AXIS ALONG AND JUST EAST OF THE MS VALLEY. CLOSER TO HOME...WEAK UPPER LEVEL RIDGING EXISTS OVER THE SOUTHERN HALF OF THE FLORIDA PENINSULA. FLOW BETWEEN THESE TWO FEATURES CONTINUES TO PUMP UP ABUNDANT AND DEEP TROPICAL MOISTURE ACROSS THE EASTERN GULF AND OVER THE FL PENINSULA. AT THE SURFACE...A WEAK PRESSURE GRADIENT IS IN PLACE BETWEEN THE SUBTROPICAL RIDGE AXIS TO OUR EAST AND NORTHEAST AND A WELL DEFINED SURFACE TROUGH/WEAK LOW ACROSS THE CENTRAL/WESTERN GULF. THIS SURFACE TROUGH TURNS EAST FROM THE MS DELTA AREA ALONG THE NE GULF COAST/I-10 CORRIDOR. LOW LEVEL FOCUS JUST SOUTH OF THIS TROUGH AXIS COMBINED WITH UPPER LEVEL SUPPORT AHEAD OF THE DIGGING MID/UPPER TROUGH IS FORCING A LARGE AREA OF CONVECTION THIS MORNING ACROSS THE NE GULF/APALACHEE BAY. TO BE HONEST...MOST OF THE RELIABLE GUIDANCE MODELS ARE NOT HANDLING THIS CONVECTIVE BLOWUP WELL AT ALL. THE ONLY MODEL THAT IS STARTING TO COME IN LINE WITH THIS FEATURE IS THE 3KM HRRR (HIGH RESOLUTION RAPID REFRESH) DUE TO ITS SOPHISTICATED RADAR INITIALIZATION METHODS. HAVE UPDATED THE FORECAST OVER THE NORTHERN MARINE ZONES AND NORTHERN NATURE COAST ZONES TO INCREASE POPS THROUGH MID-MORNING IN LINE WITH THIS LATEST HRRR FORECAST. LEVY COUNTY LOOKS TO BE RIGHT ON THE BORDER OF THIS AXIS OF FOCUS FOR CONVECTION...AND WILL HAVE A FAIRLY TIGHT GRADIENT IN THE RAIN CHANCES FROM WEST TO EAST ACROSS THE COUNTY. ELSEWHERE...OVER LAND CONDITIONS ARE RATHER QUIET IN THIS PRE-DAWN HOUR. STARTING TO SEE A FEW SHOWERS DEVELOPING OVER THE WATER FURTHER SOUTH OFF THE COASTS OF SARASOTA/CHARLOTTE AND LEE COUNTIES. THESE MORE SCT SHOWERS SHOULD MAINLY STAY OFFSHORE THROUGH MID-MORNING. && .SHORT TERM (TODAY THROUGH MONDAY)... TODAY...AS DISCUSSED ABOVE...THE MOST DIFFICULT FORECAST ZONES THIS MORNING WILL BE NORTH OF TAMPA BAY TOWARD CITRUS/LEVY COUNTY IN CLOSEST PROXIMITY TO THE LOW LEVEL TROUGH FOCUS AND UPPER LEVEL SUPPORT. BASED ON RADAR TRENDS AND LATEST HRRR FORECAST...THE HEAVIEST RAINFALL SHOULD STAY JUST WEST OF LEVY COUNTY AND MOVE UP THROUGH APALACHEE BAY...HOWEVER CERTAINLY EXPECTING SHOWERS TO BE MOVING ACROSS THOSE COUNTY IN THE NEXT SEVERAL HOURS...AND HAVE RAISED POPS FOR THIS AREA. THE HRRR DOES TRANSITION BACK TO AGREEMENT WITH THE LARGER SCALE GUIDANCE FOR THE SECOND HALF OF THE DAY AND REPOSITIONS THE HEAVIEST RAINFALL POTENTIAL BACK TOWARD THE FL PANHANDLE. FURTHER SOUTH UNDER INCREASING INFLUENCE OF THE UPPER RIDGE...THE FORECAST WILL TRANSITION TO ONE MORE REPRESENTATIVE OF A MID AUGUST DAY. WEAK RIDGING IS IN PLACE BUT CERTAINLY IS NOT ENOUGH TO SIGNIFICANTLY SUPPRESS CONVECTION. WITH A LIGHT SOUTHEAST LOW LEVEL FLOW...WILL FOLLOW A RAINFALL FORECAST CONSISTENT WITH PREFERRED ENHANCEMENT ALONG THE WEST COAST SEA-BREEZE. THIS PATTERN GENERALLY FEATURES THE EARLIEST CONVECTION IN THE AFTERNOON BREAKING OUT / MOVING INTO THE SOUTHERN /SOUTH-CENTRAL ZONES...AND THEN RIPPLING NORTHWARD ALONG THE I-75 CORRIDOR TOWARD THE TAMPA BAY AREA BY LATE AFTERNOON/EARLY EVENING. WE HAVE BEEN TRICKED THE PAST FEW DAYS WITH A PATTERN THAT SHOULD HAVE SUPPORTED ABUNDANT DIURNAL SHOWER ACTIVITY...AND COVERAGE HAS BEEN LESS THAN EXPECTED. ONCE AGAIN...TODAY LOOKS AS IF THERE IS NOT MUCH TO HOLD BACK THE STORMS DURING THE AFTERNOON. MID-LEVEL LAPSE RATES ARE NOT GREAT...BUT THIS SHOULD HAVE MORE INFLUENCE HOLDING BACK STORM INTENSITY RATHER THAN COVERAGE. ONLY OTHER CONCERN WOULD BE IF ENOUGH MID/HIGH LEVEL CLOUDS HOLD ON TO KEEP ANY DEFINED SEA-BREEZE FROM FORMING. THIS WOULD LESSEN THE OVERALL LATE DAY CONVERGENCE AND RESULTING THUNDERSTORM COVERAGE. IT IS DIFFICULT AND RISKY TO PREDICT THAT NO SEABREEZE WILL FORM THIS TIME OF YEAR...ESPECIALLY WITH LESS THAN 15 KNOTS OF BOUNDARY LAYER FLOW...WHICH IS USUALLY WHAT IT TAKES TO START PREVENTING INLAND PENETRATION. WE SHALL SEE...BUT ITS HARD BASED ON THE ENVIRONMENT NOT TO FORECAST AN ACTIVE (50-60%) AFTERNOON/EVENING OF STORMS. TONIGHT...EVENING STORMS ALONG THE I-75 CORRIDOR SHOULD PUSH OFFSHORE...BUT MAY LINGER FOR AT LEAST A FEW HOURS AFTER SUNSET...DEPENDING ON JUST HOW LATE IN THE DAY CONVECTION FIRES. IT DOES LOOK LIKE BY MIDNIGHT MOST IF NOT ALL THE ACTIVITY WILL HAVE TRANSITIONED OFFSHORE AND LEAVE MOST OF OUR LAND ZONES WITH A QUIET OVERNIGHT PERIOD. SUNDAY/MONDAY...UPPER PATTERN WILL DEAMPLIFY WITH TIME INTO THE EARLY PORTION OF NEXT WEEK ALLOWING THE UPPER RIDGE TO BUILD NORTH OVER THE ENTIRE FL PENINSULA. AT THE SAME TIME...THE SURFACE RIDGE WILL ALSO SHIFT FURTHER NORTH KEEPING OUR AREA IN A STEADY EASTERLY FLOW PATTERN. THE FORECAST FOR SUNDAY AND MONDAY WILL BE SIMILAR DUE TO THE SIMILAR SYNOPTIC PATTERNS AND FEATURE GENERALLY QUIET MORNING HOURS GIVING WAY TO INCREASING CHANCES FOR MAINLY LATE DAY/EVENING STORMS. THE EASTERLY FLOW HAS BEEN A RECURRING THEME THIS SUMMER AND IS ONE OF OUR MORE ACTIVE PATTERNS FOR THUNDERSTORMS. BOTH DAYS WILL FEATURE ABOVE CLIMO POPS OF 50-60% FOR THESE STORMS. IT IS IMPORTANT TO NOTE THAT NEITHER SUNDAY OR MONDAY WILL BE A WASHOUT AS MOST OF THESE DAYS WILL BE DRY...HOWEVER THE CHANCES ARE JUST ON THE HIGHER SIDE THAT THE PREDICTED THUNDERSTORM COVERAGE WILL PROVIDE A BRIEF DOWNPOUR AT MANY LOCATIONS. && .LONG TERM (TUESDAY THROUGH FRIDAY)... AN U/L RIDGE OVER THE WESTERN ATLANTIC WILL HOLD ACROSS FLORIDA TUESDAY...AND WILL WEAKEN WEDNESDAY AND THURSDAY AS A WEAK U/L TROUGH SINKS OVER THE SOUTHEAST U.S. AND PERSISTS INTO FRIDAY WITH SLIGHTLY LOWER HEIGHTS OVER THE FLORIDA PENINSULA. A STRONG U/L RIDGE OVER THE SOUTHERN PLAINS WILL BEGIN TO PUSH EAST SATURDAY AND WILL BUILD OVER WEST CENTRAL AND SOUTHWEST FLORIDA THROUGH THE WEEKEND. AT THE SURFACE...HIGH PRESSURE OVER THE MID ATLANTIC COAST WILL PRODUCE EASTERLY BOUNDARY LAYER FLOW ACROSS THE FLORIDA PENINSULA THROUGH THE PERIOD. TYPICAL SUMMERTIME PATTERN EACH DAY WITH THE WEST COAST SEA BREEZE BEING HELD OVER THE COASTAL COUNTIES OF WEST CENTRAL AND SOUTHWEST FLORIDA...WITH THE EAST COAST SEA BREEZE MOVING ACROSS THE PENINSULA AND COLLIDING WITH THE WEST COAST SEA BREEZE DURING THE LATE AFTERNOON/EARLY EVENING EACH DAY. SCATTERED TO NUMEROUS AFTERNOON THUNDERSTORMS EACH DAY WITH THE HIGHEST POPS OVER THE COASTAL COUNTIES. BOUNDARY LAYER WINDS MAY WEAKEN A BIT FRIDAY AND SATURDAY WHICH WOULD ALLOW THE WEST COAST SEA BREEZE TO PUSH SLIGHTLY FURTHER INLAND. STRONG CONVERGENCE ALONG THE WEST COAST SEA BREEZE BOUNDARY COMBINED WITH STRONG DAYTIME HEATING MAY ALLOW AN ISOLATED PULSE SEVERE THUNDERSTORM TO DEVELOP EACH AFTERNOON. TEMPERATURES WILL RUN A FEW DEGREES ABOVE CLIMATIC NORMALS EACH DAY. && .AVIATION... VFR CONDITIONS WILL PREVAIL THROUGH EARLY THIS MORNING. SCT LCL BKN 020-030 WILL DEVELOP MID TO LATE MORNING LIFTING TO 030-035 THIS AFTERNOON. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS VCNTY ALL TERMINALS THIS AFTERNOON...WITH LCL MVFR CIGS AND IFR VSBYS. && .MARINE... THE FORECAST WATERS WILL RESIDE WITHIN A ZONE OF SOUTHEAST FLOW BETWEEN THE SUBTROPICAL RIDGE AXIS TO OUR EAST AND NORTHEAST AND A WEAK AREA OF LOW PRESSURE AND SURFACE TROUGH OVER THE CENTRAL GULF OF MEXICO. BY THE EARLY PORTION OF NEXT WEEK...THE RIDGE AXIS WILL MOVE EVEN FURTHER NORTH AND PLACE OUR REGION IN A ZONE OF MORE CONSISTENT EASTERLY FLOW. && .FIRE WEATHER... TYPICAL SUMMER CONDITIONS ARE IN THE FORECAST THROUGH THE WEEKEND. EASTERLY FLOW WILL RESULT IN AN ACTIVE AFTERNOON AND EVENING THUNDERSTORM PATTERN THROUGH THE NEXT SEVERAL DAYS. RELATIVE HUMIDITY VALUES ARE EXPECTED TO REMAIN WELL ABOVE CRITICAL LEVELS. && .PRELIMINARY POINT TEMPS/POPS... TPA 92 79 92 78 / 50 40 50 40 FMY 93 77 93 77 / 60 30 50 30 GIF 94 75 93 75 / 50 30 50 20 SRQ 92 78 93 77 / 50 40 50 40 BKV 93 74 92 75 / 60 40 50 30 SPG 93 80 91 79 / 50 40 50 40 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...NONE. GULF WATERS...NONE. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA LONG TERM/AVIATION...OGLESBY
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
351 AM EDT SAT AUG 17 2013 .DISCUSSION... ATLC RIDGE AXIS CURRENTLY OVER CENTRAL FL WL TRANSITION NORTH OF THE AREA DURING THE DAY...OPENING UP AN ONSHORE FLOW PATTERN THAT WILL PERSIST WELL INTO NEXT WEEK. AMPLE MOISTURE REMAINS ACROSS THE REGION WITH PWAT INVOF 2 INCHES. THE EARLY ONGOING SHRA AND ISOLD TS ALONG THE INTERIOR AND WEST COAST APPEARS ASCD WITH FORCED ASCENT ASCD WITH AN UPSTREAM WAVE ALONG THE NRN GULF COAST. TODAYS FORECAST WL FAVOR INTERIOR FOR BEST RAIN CHCS DUE TO DEEPENING ONSHORE PATTERN AND BEST BOUNDARY INTERACTION POTENTIAL. MARGINAL INSTABILITY SHOULD BE AIDED BY PREVIOUSLY MENTIONED UPSTREAM WAVE AND MID RANGE SCT COVERAGE OF STORMS CAN BE EXPECTED INLAND TAPERING BACK TO ISOLD ALONG THE SPACE COAST SWD TO LAKE OKEE AND THE TREASURE COAST...WHERE MARINE SOURCE PCPN MAY BE THE MAIN MECHANISM FOR ANY MEASURABLE PRECIP. EXPECT HIGHS IN THE LOWER TO MID 90S INLAND AND AROUND 90 AT THE COAST. AS DUSK APPROACHES PRECIP POTENTIAL WL DIMINISH AND EVENTUALLY TRANSITION TO THE COAST WHERE ONSHORE MOVING SHOWERS WL AFFECT SOME AREAS INTO EARLY SUN. HIGHEST CHCS WL BE ALONG S CST WHERE MOST FAVORABLE ONSHORE TRAJECTORY WL EXIST. SUN-MON... CENTRAL FL WILL UNDERGO A SHIFT TO A DRIER WX PATTERN AS THE LIFTING H30-H20 JET OVER THE APPALACHIANS ALLOWS THE ATLC RIDGE AXIS TO REPOSITION ITSELF OVER THE DEEP SOUTH BY DAYBREAK SUN. POSITION WILL BE STABLE AS UPSTREAM JET ENERGY OVER THE SRN TIER STATES IS QUITE WEAK AND WILL NOT BE ABLE DO DISLODGE IT. POSITION OF THE RIDGE AXIS WILL GENERATE A DEEP AND STEADY E/SE FLOW ACRS CENTRAL FL...A PATTERN THAT FAVORS THE WEST PENINSULA FOR DIURNAL CONVECTION RATHER THAN THE EAST DUE LARGELY TO THE EARLY FORMATION AND DIFFUSE NATURE OF THE RESULTING EAST COAST SEA BREEZE. FURTHERMORE...LATEST RUC ANALYSIS SHOWS A NOTEWORTHY DROP IN DEEP LYR RH APPROACHING THE SRN BAHAMAS THAT WILL WORK ITS WAY INTO THE FL PENINSULA TO START THE UPCOMING WEEK. GFS MODEL SOUNDINGS CONFIRM THE ANTICIPATED DRY TREND...DROPPING PWAT VALUES FROM ARND 2.0" AT 12Z SUN TO ARND 1.7" BY 12Z MON. EVEN THE HIGHER PWAT VALUES ARE SUN ARE SOMEWHAT DECEIVING AS GFS INDICATES THE MOISTURE WILL BE EVENLY DISTRIBUTED THRU THE COLUMN... NOT CONCENTRATED IN THE LOW/MID LVLS WHERE IT WOULD SUPPORT HIGHER AMOUNTS OF DIURNAL CONVECTION. STORM POTENTIAL WILL REMAIN LOW AS THE ERLY FLOW TAPS AN AIRMASS WITH NEGLIGIBLE MID LVL VORTICITY OR OF UPR LVL JET SUPPORT. THERMODYNAMIC PROFILE MAY PROVIDE SOME PUNCH AS UPSTREAM H50 TEMPS DROP INTO THE -7C TO -8C RANGE AND H85-H50 LAPSE RATES STEEPEN TO 6.0-6.5C/KM. HOWEVER...ANY STRONG ACTIVITY WOULD TEND TO FORM W OF THE FL TURNPIKE AS THE DEEP ERLY FLOW WILL PUSH THE SEA BREEZE RAPIDLY INLAND. PRECIP COVERAGE AOB 40PCT WITH HIGHEST COVERAGE OVER THE INTERIOR SUN AFTN TO GIVE A NOD TO THE AFOREMENTIONED HIGHER PWAT VALUES. ONSHORE FLOW WILL KEEP MAX TEMPS IN THE U80S/L90 ALONG THE COAST... INTERIOR WARMING TO THE L/M90S. MIN TEMPS L/M70S. TUE-FRI... LITTLE CHANGE TO THE CURRENT PHILOSOPHY...STABLE POSITION OF THE ATLC RIDGE AXIS WILL MAINTAIN A DEEP ERLY FLOW ACRS CENTRAL FL FOR MUCH OF THE WEEK THAT WILL FOCUS DIURNAL CONVECTION OVER THE W PENINSULA. POPS 30-40PCT...HIGHER OVER THE INTERIOR DUE TO THE EARLY FORMATION OF THE EAST COAST SEA BREEZE. MAX TEMPS WITHIN A DEG OR TWO OF CLIMO AVG...MIN TEMPS 3-5F ABV AVG DUE TO THE PERSISTENT ONSHORE FLOW. && .AVIATION... ISOLD EARLY SHOWERS WITH ASCD CIGS NR 035-040FT NR ISM-LEE THROUGH 14Z TRANSITION TO ADTL SHOWERS WITH A FEW STORMS MOVING NWD FM 15Z THROUGH 18Z WILL FILL IN ACROSS PRIMARILY INTERIOR SECTIONS AWAY FROM THE E COAST THE REGION THROUGH MID AFTN. BEST PERIOD FOR SCT MVFR AND ISOLD IFR CONDS AT TAF SITES WL OCCUR FM 18Z-22Z AND INLAND. OCNL CIGS FM 025-035 WL OCCUR IN SHOWERS ALONG WITH OCNL-FRQT LTG AND WND G30-35KT IN ANY STRONGER TS. && .MARINE... FAVORABLE SEA HGHTS FOR SMALL CRAFT DURIN THE DAY WITH INDICATED SIG WV CURRENTLY MEASURING 1-2 FT AND LIKELY 2-3 FT OVER THE OUTERMOST WATERS. SLOWLY INCREASING HGHTS CAN BE EXPECTED INTO TONIGHT WITH DEVELOPMENT OF ONSHORE GRADIENT WINDS AS HIGH PRESSURE LIFTS NORTH OF THE REGION. SUN-WED...ATLC RIDGE WILL REPOSITION ITSELF OVER THE DEEP SOUTH BY DAYBREAK WHERE IT WILL REMAIN THRU MIDWEEK. RIDGE POSITION WILL GENERATE A STEADY STATE GENTLE TO MODERATE E/SE BREEZE. THESE WINDS WILL PUSH A SMALL ERLY SWELL INTO THE LCL ATLC...KEEPING SEAS 3-4FT THRU MON. SEAS WILL SUBSIDING TO 2-3FT NEARSHORE AND 3-4FT OFFSHORE TUE THE SWELL DAMPENS. ISOLD SHRAS/ TSRAS THRU THE PD. && .PRELIMINARY POINT TEMPS/POPS... DAB 91 76 89 77 / 30 20 30 20 MCO 94 76 93 76 / 40 20 40 20 MLB 92 78 89 79 / 30 30 30 20 VRB 91 77 90 77 / 30 30 30 20 LEE 92 76 93 77 / 40 20 40 20 SFB 94 76 93 77 / 40 20 40 20 ORL 94 77 93 77 / 40 20 40 20 FPR 90 76 90 78 / 30 30 30 20 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ SHORT TERM...PENDERGRAST LONG TERM....BRAGAW
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
339 AM EDT Sat Aug 17 2013 ...HEAVY RAINFALL AND FLOODING CONCERNS EXPECTED AGAIN TODAY... .NEAR TERM [Thru TODAY]... We continue in a very wet and unsettled pattern. During the overnight hours, shortwave energy moving from the Cntrl/Srn Gulf of Mex has energized another band of deep tropical moisture (PWATS 2.1-2.2 inches) with training cells and interacted with a stalled front producing moderate to locally heavy rains across portions of the local area, especially the Panhandle. This aggravated the flooding situation which necessitated the issuance of a flood warning for Jackson and Washington counties. RAP soundings imply that low level steering flow was switching from SW to more sly feeding more of this moisture Nwd into our AL/GA counties near the front yielding rain rates of up to 2-3 inches per hour. By 3 AM EDT, strong to severe storms began developing across the nearshore waters and this will soon move over coastal counties. The large scale pattern continues to amplify with little change in last 12 hrs providing all the ingredients necessary today for a continued widespread heavy rain event further aggravating the flooding situation. Aloft, ridge over Wrn 1/3d and deep trough over Ern 2/3rd of Conus with axis down MS Valley. A deep 580DM low will centered over NE Missouri with a trough axis extending into the northwestern Gulf of Mex. A potent vortmax over AR/TN border with 90kt upper jet round the base of the trough placing the area in the favorable right entrance region. Several small shortwaves riding down base of trough nudging it ewd. All this increasing upper lift/diffluence over mainly WRN CWA. At the same time, a low/tropical wave was located in the SW Gulf on Mex (NW of Campeche). The combination of these features has allowed for sfc-H4 SW unidirectional flow providing a deep conveyor belt of tropical moisture spreading Newd across our local area. At the surface, front remains largely stalled from Srn Walton county Nwwd to just south of Marianna/Bainbridge into SE GA yielding SWLY flow. However the combination of diurnal heating plus building H5 ridging across the Wrn Atlc and FL Peninsula should lift front Nwd thru the day placing more of area in warm sector. Convergence along this boundary should continue to serve as the focus for low level lift and where heaviest rains should occur. Model soundings show area PWATS in excess of 2 inches. Flash flooding will remain a serious concern as activity continues to train over areas which have already received significant rainfall. As the Gulf system moves further Wwd, guidance places the highest QPF and highest PoPs over the NW third of our forecast area. With many of these areas already saturated from a very wet summer, flash flooding will continue to be closely monitored. Thus the flash flood watch remains in effect for the entire area but Ern sections should may be dropped by this aftn. Will have categorical PoPs for most of the area with temperatures well below normal. See the hydrology section of this product for more details on the potential. As far as strong to severe storms, the existence of a very moist boundary layer and weak lapse rates argue against these storms, however with upper trough/jet/vort, cant discount wet microbursts with gusty to damaging winds best bet. SPC keeps us in 5% severe prob. Will go with CAT POPS west half and likely POPS east half with heavy rain in grids. Under cloudy and rain conditions, Max temps to remain well below normal, from around 80 SE AL to mid to upper 80s SE Big Bend. && .SHORT TERM [Tonight Through Monday]... As the Gulf system continues to shift Wwd into Wrn Gulf, expect heavy rain to decrease from E-W with the corridor of heaviest rain progressively sliding to west of our forecast area. However, the continued influence of the trough along the MS Valley (even thought its deamplifying) and now SW-NE oriented quasi-stnry front should combine for sct-likely POPs thru the period. For tonight, the deep layer conveyor belt will diminish but FL Panhandle and SE AL will remain in a favorable position to receive additional heavy rain and lingering flooding concerns. By Sun, the upper low will lift newd towards OH River Valley but trough and front will linger while the Gulf system should be far enough west for little impact. However, latest guidance indicates that a piece of this feature will shear Nwd strengthening H85 flow and keeping moisture in at least our Wrn CWA even with the Atlc subtropical ridge building Nwwd into our area. By Mon, upper ridge over Wrn Atlc will build into local area. We will return to a more seasonal pattern of sct seabreeze driven convection as POPs decrease and max temps will return to near climo. Will go with 60-40% NW-SE POPs tonight, 60-50% on Sun and 50-30% N-S on Mon. Lows tonight around 70. Highs Sun Mid 80s NW to around 90 SE rising on Mon to upper 80s NW to lower 90s SE. && .LONG TERM [Monday Night through Friday]... Upper trough over the Lower Mississippi Valley is forecast to linger through the first half of next week keeping a moist and unstable airmass in place over the tri-state area. This will keep PoPs relatively high through at least Tuesday. By later in the week, there is more uncertainty in the guidance as to how much ridging will build back over the region, with the ECMWF keeping the upper trough in tact and the GFS indicating a stronger ridge. Being well into the extended, will keep conditions close to climo as a compromise. && .AVIATION... [Through 06z Sunday] Low cigs and showers with embedded convection will prevail with MVFR to IFR conditions expected. && .MARINE... Winds and seas will be on the increase through the weekend especially around any convection and especially over the western waters, as a trough of low pressure lingers to the north and west. However conditions should remain below exercise caution levels through Sunday. Winds and seas will diminish early next week. && .FIRE WEATHER... Abundant moisture and rainfall will prevent red flag conditions from being met well into next week. && .HYDROLOGY... Up until this morning, except for the FL Panhandle, showers have been progressive enough and not training which has kept the flood threat low. However, this should change today as the heaviest rains of this wet period are expected with widespread average rainfall amounts of 3 to 5 inches still anticipated mainly Wrn areas. Isolated higher totals are expected, possibly upward of 5 to 8 inches in some locations. River flooding will become an increasing concern by late today and into next week, especially depending on where the heaviest rainfall ends up occurring. The current thinking is that much of the heaviest rains will occur in the lower half of the basins. Thus, if the latest forecast holds, the Choctawhatchee Basin from Geneva through Bruce would easily return to minor flood stage late in the weekend with the potential for moderate flooding from Caryville southward to Bruce early next week. The Chipola has some capacity for heavy rainfall, but if rainfall amounts trend higher than expected, minor flooding would be a possibility at Marianna and Altha early next week. Into Southeast Alabama, soils are especially saturated and area creeks and stream will quickly respond to any significant rainfall. Minor flooding along the Choctawhatchee and Pea Rivers could occur quickly in this scenario late this weekend. In Southern Georgia and the Florida Big Bend, current projections move the Apalachicola, Flint, and Ochlockonee River systems to near flood stage with anticipated rainfall, though heavier amounts would easily lead to minor flooding, especially in the lower portions of these basins where heavier rains were received in July. Lighter rainfall amounts are anticipated further east into the Withlacoochee and Suwannee River basins and the current anticipation is for these rivers to remain below flood stage into next week. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 84 71 91 74 91 / 80 60 60 50 50 Panama City 83 75 88 77 86 / 90 60 60 50 50 Dothan 81 70 86 71 88 / 90 60 60 40 50 Albany 82 71 88 73 90 / 90 60 60 30 50 Valdosta 85 70 91 73 91 / 70 60 50 40 50 Cross City 88 73 91 72 91 / 50 40 50 40 50 Apalachicola 85 78 87 79 87 / 80 60 60 50 50 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...FLASH FLOOD WATCH through this evening for Coastal Dixie- Coastal Franklin-Coastal Jefferson-Coastal Taylor-Coastal Wakulla-Gadsden-Inland Dixie-Inland Franklin-Inland Jefferson-Inland Taylor-Inland Wakulla-Lafayette-Leon- Liberty-Madison. FLASH FLOOD WATCH through Sunday evening for Calhoun-Central Walton-Coastal Bay-Coastal Gulf-Holmes-Inland Bay-Inland Gulf-Inland Walton-Jackson-South Walton-Washington. GA...FLASH FLOOD WATCH through this evening for Baker-Ben Hill- Berrien-Brooks-Calhoun-Clay-Colquitt-Cook-Decatur- Dougherty-Early-Grady-Irwin-Lanier-Lee-Lowndes-Miller- Mitchell-Quitman-Randolph-Seminole-Terrell-Thomas-Tift- Turner-Worth. AL...FLASH FLOOD WATCH through Sunday evening for Coffee-Dale- Geneva-Henry-Houston. GM...None. && $$ Hydrology...Block/Godsey LONG TERM...Camp AVIATION/FIRE WX...DVD REST OF DISCUSSION...BLOCK
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
940 PM EDT SUN AUG 18 2013 .UPDATE... HAVE ADJUSTED POPS FOR A FEW HOURS BASED ON RADAR. SCATTERED CONVECTION STILL MOSTLY ACROSS CENTRAL ZONES. WEDGE STILL HOLDING JUST ABOUT ATLANTA TO ATHENS AND MAY NOT MUVE MUCH MORE OVERNIGHT. WILL KEEP THE FLASH FLOOD WATCH UNTIL EXPIRATION. 41 .PREVIOUS... .SHORT TERM /TONIGHT THROUGH MONDAY/... PRIMARY CONCERNS FOR THE SHORT TERM PERIOD WILL BE WHERE MODERATE TO HEAVY RAIN AXIS SETS UP AND WHAT NEEDS TO BE DONE WITH THE FLASH FLOOD WATCH AS A RESULT. AFTER A WET START TO THE DAY...ACTIVITY HAS DWINDLED FOR THE MOST PART WITH JUST SOME PASSING SHOWERS THROUGH THE ATLANTA METRO NOW HEADING INTO NORTHEAST GEORGIA. FOCUS NOW SHIFTS TO THE SOUTHEAST WHERE LOCAL WRF AND HRRR HAVE BEEN BEEN HONING IN ON WITH THUNDERSTORMS DEVELOPING NICELY OVER THE FAR SOUTHEAST AT THIS HOUR. SPC SREF SHOWS INSTABILITY INCREASING AS WARM FRONT EASES NORTHWARD WITH AREAS AROUND TOOMBS AND MONTGOMERY COUNTIES SHOWING IN EXCESS OF 1000 J/KG OF AVAILABLE CAPE. WOULD EXPECT A LINE OF SHOWERS AND STORMS TO DEVELOP IN THIS AREA AND PROGRESS TOWARD MACON LATER THIS AFTERNOON INTO THE EVENING. ADDITIONAL ACTIVITY COULD FORM AHEAD OF THIS AS WELL IN THE MORE UNSTABLE SECTION FROM COLUMBUS TO JUST SOUTH OF ATHENS. ALSO WATCHING GULF INITIATED STORMS AS THESE LOOK TO AFFECT THE SOUTH AS WELL TONIGHT WITH STORMS ALREADY PUSHING INTO THE GEORGIA PORTION FROM THE FLORIDA PANHANDLE. THERE IS SOME DISPARITY IN SHORT TERM MODELS ON HOW THIS WILL EVENTUALLY EVOLVE THIS EVENING WITH NAM12 INDICATING MORE DEVELOPMENT ON THE WESTERN SIDE OF THE AREA VERSUS THE SOUTH. THIS UNCERTAINTY IS PROBLEMATIC GIVEN THE FLOOD WATCH ORIENTATION WHICH IS CURRENTLY OVER THE WEST. IF CURRENT TRENDS HOLD HOWEVER...THE SOUTHERN SECTIONS WOULD BE MORE UNDER THE GUN. WITH THE UNCERTAINTY INVOLVED...WILL LET THE EVENING SHIFT TAKE ANOTHER LOOK AT THIS DEVELOPING EVENT TO SEE IF FLOOD WATCH NEEDS TO CONTINUE AND FOR WHAT AREAS. FOR MONDAY...PRETTY MUCH THE SAME PATTERN BUT WITH WEDGE CONTINUING TO WEAKEN AND MORE MOISTURE AVAILABLE FOR THE NORTHERN ZONES AS WELL AS INSTABILITY. WENT LIKELY FOR MOST AREAS...FAVORING THE SOUTH ONCE AGAIN...CLOSER TO THE VICINITY OF STALLED OUT BOUNDARY. STILL USED SOME SLIGHT CAD INFLUENCES FOR THE HIGH TEMPS MONDAY BUT SHOULD WARM NICELY TO UPPER 70S NORTH TO LOWER 80S SOUTH. DEESE .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... BUMPED POPS UP SOME INTO THURSDAY TO ACCOUNT FOR THE VERY MOIST AIRMASS OVER THE AREA. OTHERWISE NO MAJOR CHANGES. BDL PREVIOUS DISCUSSION... THE WET PATTERN CONTINUES INTO THE EXTENDED. THE STATIONARY FRONT OVER SOUTH GA TODAY WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY AND SHOULD BE SOME WHERE BETWEEN ATL AND MCN BY TUE MORNING. THIS FRONT WILL WEAKEN SOME BUT IT WILL STILL ACT AS A GUIDE FOR GULF MOISTURE TO MOVE NORTHWARD ACROSS THE REGION THROUGH THE MIDDLE OF THE WEEK. THE WEDGE LOOKS TO FINALLY BREAK DOWN SOMETIME MONDAY WHICH WILL ALSO ALLOW FOR A MORE DIURNALLY DRIVEN PRECIP PATTERN THROUGH DAY 7. BEST TIMING FOR THE HEAVIEST RAIN WILL BE IN THE SHORT TERM BUT DEEP TROPICAL MOISTURE REMAINS OVER THE REGION THROUGH WED/THU WITH PRECIPITABLE WATERS IN THE 1.5 TO 2.0 INCH RANGE THROUGH THU. THE DEEPER MOISTURE MOVES NORTH AND EAST OF THE STATE BY THU NIGHT BUT THE DIURNAL CONVECTIVE TREND WILL CONTINUE INTO NEXT WEEKEND. TEMPS WILL BEGIN TO REBOUND BY TUE AND BE BACK TO NEAR SEASONAL NORMS BY THU/FRI. 01 && .AVIATION... 00Z UPDATE... FRONTAL BOUNDARY JUST SOUTH OF ATL SHOULD REMAIN NEARLY STATIONARY THROUGH THE NIGHT. LIGHT EAST WINDS WILL PERSIST OVERNIGHT AND CONTINUE AROUND 10KT AFTER 14Z MONDAY. ALL SITES WILL GO IFR BY LATE THIS EVENING AND THEN LIFR FOR THE EARLY MORNING HOURS. PREVAILING SHOWERS CONTINUING WITH SOME SCATTERED THUNDERSTORMS. A FEW STORMS POSSIBLY SEVERE. //ATL CONFIDENCE...00Z UPDATE... MEDIUM ON ALL ELEMENTS 41 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 69 81 69 79 / 50 60 50 70 ATLANTA 69 79 70 79 / 70 50 40 60 BLAIRSVILLE 65 76 66 78 / 70 50 50 60 CARTERSVILLE 69 79 69 78 / 70 50 50 60 COLUMBUS 71 83 72 85 / 50 60 40 70 GAINESVILLE 68 78 69 76 / 70 50 50 70 MACON 70 82 70 82 / 40 60 40 60 ROME 69 80 70 80 / 70 50 50 60 PEACHTREE CITY 70 80 71 79 / 60 50 40 60 VIDALIA 72 86 72 86 / 40 60 40 40 && .FFC WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING ZONES: BARTOW...BIBB...BLECKLEY...BUTTS...CARROLL...CATOOSA... CHATTAHOOCHEE...CHATTOOGA...CHEROKEE...CLAYTON...COBB...COWETA... CRAWFORD...CRISP...DADE...DEKALB...DODGE...DOOLY...DOUGLAS... FANNIN...FAYETTE...FLOYD...GILMER...GORDON...HARALSON...HARRIS... HEARD...HENRY...HOUSTON...LAMAR...MACON...MARION...MERIWETHER... MONROE...MURRAY...MUSCOGEE...NORTH FULTON...PAULDING...PEACH... PICKENS...PIKE...POLK...PULASKI...ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING...STEWART...SUMTER...TALBOT...TAYLOR... TELFAIR...TROUP...TWIGGS...UPSON...WALKER...WEBSTER... WHITFIELD...WILCOX. && $$ SHORT TERM...DEESE LONG TERM....BDL AVIATION...41
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
800 PM EDT SUN AUG 18 2013 .SHORT TERM /TONIGHT THROUGH MONDAY/... PRIMARY CONCERNS FOR THE SHORT TERM PERIOD WILL BE WHERE MODERATE TO HEAVY RAIN AXIS SETS UP AND WHAT NEEDS TO BE DONE WITH THE FLASH FLOOD WATCH AS A RESULT. AFTER A WET START TO THE DAY...ACTIVITY HAS DWINDLED FOR THE MOST PART WITH JUST SOME PASSING SHOWERS THROUGH THE ATLANTA METRO NOW HEADING INTO NORTHEAST GEORGIA. FOCUS NOW SHIFTS TO THE SOUTHEAST WHERE LOCAL WRF AND HRRR HAVE BEEN BEEN HONING IN ON WITH THUNDERSTORMS DEVELOPING NICELY OVER THE FAR SOUTHEAST AT THIS HOUR. SPC SREF SHOWS INSTABILITY INCREASING AS WARM FRONT EASES NORTHWARD WITH AREAS AROUND TOOMBS AND MONTGOMERY COUNTIES SHOWING IN EXCESS OF 1000 J/KG OF AVAILABLE CAPE. WOULD EXPECT A LINE OF SHOWERS AND STORMS TO DEVELOP IN THIS AREA AND PROGRESS TOWARD MACON LATER THIS AFTERNOON INTO THE EVENING. ADDITIONAL ACTIVITY COULD FORM AHEAD OF THIS AS WELL IN THE MORE UNSTABLE SECTION FROM COLUMBUS TO JUST SOUTH OF ATHENS. ALSO WATCHING GULF INITIATED STORMS AS THESE LOOK TO AFFECT THE SOUTH AS WELL TONIGHT WITH STORMS ALREADY PUSHING INTO THE GEORGIA PORTION FROM THE FLORIDA PANHANDLE. THERE IS SOME DISPARITY IN SHORT TERM MODELS ON HOW THIS WILL EVENTUALLY EVOLVE THIS EVENING WITH NAM12 INDICATING MORE DEVELOPMENT ON THE WESTERN SIDE OF THE AREA VERSUS THE SOUTH. THIS UNCERTAINTY IS PROBLEMATIC GIVEN THE FLOOD WATCH ORIENTATION WHICH IS CURRENTLY OVER THE WEST. IF CURRENT TRENDS HOLD HOWEVER...THE SOUTHERN SECTIONS WOULD BE MORE UNDER THE GUN. WITH THE UNCERTAINTY INVOLVED...WILL LET THE EVENING SHIFT TAKE ANOTHER LOOK AT THIS DEVELOPING EVENT TO SEE IF FLOOD WATCH NEEDS TO CONTINUE AND FOR WHAT AREAS. FOR MONDAY...PRETTY MUCH THE SAME PATTERN BUT WITH WEDGE CONTINUING TO WEAKEN AND MORE MOISTURE AVAILABLE FOR THE NORTHERN ZONES AS WELL AS INSTABILITY. WENT LIKELY FOR MOST AREAS...FAVORING THE SOUTH ONCE AGAIN...CLOSER TO THE VICINITY OF STALLED OUT BOUNDARY. STILL USED SOME SLIGHT CAD INFLUENCES FOR THE HIGH TEMPS MONDAY BUT SHOULD WARM NICELY TO UPPER 70S NORTH TO LOWER 80S SOUTH. DEESE .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... BUMPED POPS UP SOME INTO THURSDAY TO ACCOUNT FOR THE VERY MOIST AIRMASS OVER THE AREA. OTHERWISE NO MAJOR CHANGES. BDL PREVIOUS DISCUSSION... THE WET PATTERN CONTINUES INTO THE EXTENDED. THE STATIONARY FRONT OVER SOUTH GA TODAY WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY AND SHOULD BE SOME WHERE BETWEEN ATL AND MCN BY TUE MORNING. THIS FRONT WILL WEAKEN SOME BUT IT WILL STILL ACT AS A GUIDE FOR GULF MOISTURE TO MOVE NORTHWARD ACROSS THE REGION THROUGH THE MIDDLE OF THE WEEK. THE WEDGE LOOKS TO FINALLY BREAK DOWN SOMETIME MONDAY WHICH WILL ALSO ALLOW FOR A MORE DIURNALLY DRIVEN PRECIP PATTERN THROUGH DAY 7. BEST TIMING FOR THE HEAVIEST RAIN WILL BE IN THE SHORT TERM BUT DEEP TROPICAL MOISTURE REMAINS OVER THE REGION THROUGH WED/THU WITH PRECIPITABLE WATERS IN THE 1.5 TO 2.0 INCH RANGE THROUGH THU. THE DEEPER MOISTURE MOVES NORTH AND EAST OF THE STATE BY THU NIGHT BUT THE DIURNAL CONVECTIVE TREND WILL CONTINUE INTO NEXT WEEKEND. TEMPS WILL BEGIN TO REBOUND BY TUE AND BE BACK TO NEAR SEASONAL NORMS BY THU/FRI. 01 && .AVIATION... 00Z UPDATE... FRONTAL BOUNDARY JUST SOUTH OF ATL SHOULD REMAIN NEARLY STATIONARY THROUGH THE NIGHT. LIGHT EAST WINDS WILL PERSIST OVERNIGHT AND CONTINUE AROUND 10KT AFTER 14Z MONDAY. ALL SITES WILL GO IFR BY LATE THIS EVENING AND THEN LIFR FOR THE EARLY MORNING HOURS. PREVAILING SHOWERS CONTINUING WITH SOME SCATTERED THUNDERSTORMS. A FEW STORMS POSSIBLY SEVERE. //ATL CONFIDENCE...00Z UPDATE... MEDIUM ON ALL ELEMENTS 41 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 69 81 69 79 / 50 60 50 70 ATLANTA 69 79 70 79 / 70 50 40 60 BLAIRSVILLE 65 76 66 78 / 70 50 50 60 CARTERSVILLE 69 79 69 78 / 70 50 50 60 COLUMBUS 71 83 72 85 / 50 60 40 70 GAINESVILLE 68 78 69 76 / 70 50 50 70 MACON 70 82 70 82 / 40 60 40 60 ROME 69 80 70 80 / 70 50 50 60 PEACHTREE CITY 70 80 71 79 / 60 50 40 60 VIDALIA 72 86 72 86 / 40 60 40 40 && .FFC WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING ZONES: BARTOW...BIBB...BLECKLEY...BUTTS...CARROLL...CATOOSA... CHATTAHOOCHEE...CHATTOOGA...CHEROKEE...CLAYTON...COBB...COWETA... CRAWFORD...CRISP...DADE...DEKALB...DODGE...DOOLY...DOUGLAS... FANNIN...FAYETTE...FLOYD...GILMER...GORDON...HARALSON...HARRIS... HEARD...HENRY...HOUSTON...LAMAR...MACON...MARION...MERIWETHER... MONROE...MURRAY...MUSCOGEE...NORTH FULTON...PAULDING...PEACH... PICKENS...PIKE...POLK...PULASKI...ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING...STEWART...SUMTER...TALBOT...TAYLOR... TELFAIR...TROUP...TWIGGS...UPSON...WALKER...WEBSTER... WHITFIELD...WILCOX. && $$ SHORT TERM...DEESE LONG TERM....BDL AVIATION...41
AREA FORECAST DISCUSSION
NWS PEACHTREE CITY GA
346 PM EDT SAT AUG 17 2013 ...WET PATTERN TO CONTINUE FOR THE REMAINDER OF THE WEEKEND... .SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/... LOW LEVEL FLOW OVER 300K ISENTROPIC SURFACE HAS BECOME MORE SOUTHERLY AND CROSS FLOW ALLOWING FOR ENHANCED LIFT NORTH OF FRONTAL BOUNDARY OVER SOUTH GEORGIA. ENTRENCHED WEDGE ALSO PROVIDING FOR ADDITIONAL FOCUS FOR THE DEVELOPMENT OF WIDESPREAD LIGHT TO MODERATE RAIN OVER THE AREA. IN SITU CONDITIONS WITHIN WEDGE ONLY HELPING TO STRENGTHEN ITS GRIP ON THE LOCAL AREA WITH TEMPS REMAINING IN THE 60S FOR ALL OF NORTH GEORGIA. HAVE PRETTY MUCH KEPT STEADY TEMPS IN THE FORECAST FOR THE SHORT TERM PERIOD WHICH IS SOME 3 TO 6 DEGREES BELOW MODEL GUIDANCE WHICH IS NOT PERFORMING WELL WITH THIS SUMMER WEDGE SCENARIO. FOR TONIGHT...AXIS OF PRECIP SHOULD REMAIN IN ROUGHLY THE SAME LOCATION AS MAIN FEATURES ARE STEADY STATE THROUGH THE OVERNIGHT HOURS. EXPECT AT LEAST SOME DIURNAL INFLUENCES TO PRECIP COVERAGE AND WILL GRADUALLY DECREASE...BUT KEEP A LARGE AREA OF LIKELY THROUGH SUNDAY MORNING. GFS AS WELL AS SHORT TERM HRRR AND WRF IN AGREEMENT IN DEPICTING A STRONG SHORTWAVE PUSHING OUT OF THE GULF TOWARD DAYBREAK SUNDAY IN CONJUNCTION WITH A POSSIBLE BREAKDOWN OF WEDGE FOR THE EXTREME SOUTHERN SECTIONS. SHOULD SEE REDEVELOPMENT OF SHOWERS ON THE WEST SIDE OF THE FORECAST AREA WITH CONVECTIVE ELEMENTS INCREASING AS WELL WHICH WILL LEAD TO HIGHER RAINFALL RATES FROM COLUMBUS TO MACON. UPPER LEVEL FEATURE WILL LIFT NORTH THROUGH LA GRANGE AND ATLANTA INTO THE AFTERNOON WITH CATEGORICAL POPS EXPECTED ONCE AGAIN. BEST CAPE REMAINS TO THE SOUTH BUT THE ADDITION OF SHORTWAVE ENERGY COULD HELP OVERCOME A LACK OF INSTABILITY FOR THE NORTH AND WILL NEED TO BE MONITORED CLOSELY. AT THE VERY LEAST...POTENTIAL FOR HEAVIER SUSTAINED SHOWERS WILL INCREASE SUNDAY. WILL LET MID SHIFT TAKE ANOTHER LOOK BUT MAY NEED TO EXTEND FLOOD WATCH THROUGH THE REMAINDER OF SUNDAY. PRETTY MUCH THE SAME INTO SUNDAY NIGHT WITH FOCUS SHIFTING TO NORTHWEST GA WITH SHORTWAVE. HAVE BACKED OFF OF CATEGORICAL AS DIURNAL INFLUENCES SHOULD STILL BE IN PLAY BUT STILL PAINTING LIKELY FOR THE FIRST PART OF THE OVERNIGHT PERIOD. DEESE .LONG TERM /MONDAY THROUGH SATURDAY/... CHANGES TO THE LONG TERM ARE MINOR. HAVE TWEAKED POPS BASED OFF THE LATEST MODELS. OTHER THAN THAT...ADJUSTED TEMPERATURES DOWN A DEGREE OR SO FROM GUIDANCE FOR MONDAY. PREVIOUS DISCUSSION FOLLOWS. 11 /ISSUED AT 452 AM EDT SAT AUG 17 2013/ THE GFS AND ECMWF MODELS REMAIN CONSISTENT IN CONTINUING THIS WET PATTERN THROUGH THE WEEKEND AND INTO NEXT WEEK. THE STATIONARY FRONT OVER SOUTH GA WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY/TUE THEN GRADUALLY DISSIPATE. AN EASTERLY LOW LEVEL FLOW WITH ATLANTIC MOISTURE AND OVERRUNNING TROPICAL MOISTURE FROM THE GULF WILL COMBINE WITH A SERIES OF UPPER LEVEL DISTURBANCES TO PRODUCE WIDESPREAD SHOWERS AND A FEW THUNDERSTORMS THROUGH WED/THU. BEST TIMING FOR HEAVY RAIN WILL BE IN THE SHORT TERM BUT DEEP TROPICAL MOISTURE REMAIN OVER THE REGION THROUGH DAY 6/7. PRECIPITABLE WATERS REMAIN IN THE 1.5 TO 2.0 INCH RANGE THROUGH THU. THE MODELS ARE TRYING TO ERODE THE WEDGE A BIT TO FAST ALLOWING INSTABILITIES TO INCREASE ACROSS THE AREA MONDAY. THERE APPEARS TO BE NO EROSION MECHANISM AND REINFORCEMENT OF THE COLD AIR DAMMING IS LIKELY TO CONTINUE WITH SOLAR SHELTERING FROM OVERRUNNING MOISTURE AND ANY EVAPORATIONAL COOLING. THIS WEDGE SHOULD CONTINUE AT LEAST INTO EARLY NEXT WEEK ALLOWING INSTABILITY INDICES TO STAY LOW FOR THIS TIME OF YEAR. WILL DEFINITELY NEED TO WATCH THIS AS IT WILL PLAY A BIG ROLE IN OUR WEATHER PATTERN. TEMPS SHOULD BEGIN TO REBOUND BY TUE BUT STILL STAY A BIT BELOW SEASONAL NORMS. 01 && .HYDROLOGY... WITH CHANGING MODEL DEPICTIONS OF PRECIP PATTERN COMES CHANGES IN ANTICIPATED HEAVIEST PRECIP CORE. EXPECTING CONVECTIVE ELEMENTS TO EMANATE OUT OF THE GULF TONIGHT AND TRANSITION ON THE WESTERN SIDE OF THE FORECAST AREA SUNDAY. THIS WILL PUT US SLIGHTLY OUT OF PHASE WITH CURRENT FLOOD WATCH BUT FEELING IS THAT EVEN AREAS OVER THE SOUTH THAT RECEIVE LESS RAINFALL COULD STILL REALIZE FLOODING GIVEN EXTREMELY LOW FLASH FLOOD GUIDANCE VALUES. HAVE FLOOD WATCH GOING THROUGH 12Z SUNDAY NIGHT WITH POSSIBLE EXPANSION BY MID SHIFT IN BOTH TIME AND AREA. && .CLIMATE... RECORDS FOR 08-17 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAHN 105 1954 73 1939 76 2010 60 1967 2007 1948 1995 KATL 101 2007 74 1939 76 2010 62 1948 1954 1892 2000 1892 1995 KCSG 102 2000 82 1979 78 2001 66 1961 KMCN 103 2000 76 1939 77 2010 60 1967 1954 1952 RECORDS FOR 08-18 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAHN 103 1995 70 1905 76 1946 62 1979 1976 1964 KATL 101 2000 70 1981 80 2000 62 1964 1995 1905 1879 KCSG 104 2000 78 1981 78 2000 62 1948 1995 KMCN 104 2000 75 1981 77 2000 63 1948 1905 1995 1951 RECORDS FOR 08-19 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAHN 105 1925 75 1981 75 1934 61 1976 KATL 99 1925 69 1897 76 2010 63 1879 2007 1993 KCSG 100 2000 78 1992 78 2010 64 1958 1977 KMCN 101 1983 77 1977 77 1999 64 2006 1925 1976 RECORDS FOR 08-20 MAX TEMPERATURE MIN TEMPERATURE STATION HIGH LOW HIGH LOW ------- ---------- ---------- ---------- ---------- KAHN 107 1925 75 1976 77 1983 59 1943 1953 KATL 100 1925 77 1953 80 1925 59 1927 1927 KCSG 102 1983 78 1981 77 2010 66 1961 1948 KMCN 105 1925 74 1897 76 2010 62 1943 1983 1936 && .AVIATION... 18Z UPDATE... PRECIPITATION SHIELD WHICH NOW ENCOMPASSES ALL THE AREA TAF SITES HAS RESULTED IN LOWER CIGS AND VSBYS MAINTAINING THEMSELVES THIS AFTERNOON. MOST SITES ARE IN THE IFR RANGE WITH BRIEF DIPS INTO LIFR AS HEAVIER SHRA PASS THROUGH. LOOKS LIKE A PERSISTENCE FORECAST THIS CYCLE WITH IFR TO CONTINUE INTO THE EVENING HOURS...TRANSITIONING TO A LONG PERIOD OF LIFR INTO THE OVERNIGHT PERIOD. SHRA SHOULD EASE BY LATE THIS EVENING BUT ADDITIONAL SHRA EXPECT BY MID MORNING SUNDAY. //ATL CONFIDENCE...18Z UPDATE... MEDIUM ON CIGS. HIGH ON REMAINING ELEMENTS. DEESE && .PRELIMINARY POINT TEMPS/POPS... ATHENS 64 71 68 82 / 100 70 50 40 ATLANTA 64 72 69 81 / 80 100 70 50 BLAIRSVILLE 61 69 64 78 / 80 100 70 40 CARTERSVILLE 64 71 68 82 / 70 100 70 40 COLUMBUS 69 81 72 85 / 80 80 60 50 GAINESVILLE 63 71 68 79 / 80 100 70 40 MACON 68 79 71 85 / 100 60 50 50 ROME 66 71 69 84 / 60 100 70 40 PEACHTREE CITY 66 73 69 82 / 80 100 70 50 VIDALIA 69 82 72 87 / 100 40 30 50 && .FFC WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH THROUGH SUNDAY MORNING FOR THE FOLLOWING ZONES: BALDWIN...BIBB...BLECKLEY...BUTTS...CHATTAHOOCHEE... CRAWFORD...CRISP...DODGE...DOOLY...EMANUEL...GLASCOCK...GREENE... HANCOCK...HARRIS...HOUSTON...JASPER...JEFFERSON...JOHNSON... JONES...LAMAR...LAURENS...MACON...MARION...MERIWETHER...MONROE... MONTGOMERY...MORGAN...MUSCOGEE...PEACH...PIKE...PULASKI... PUTNAM...SCHLEY...STEWART...SUMTER...TALBOT...TALIAFERRO... TAYLOR...TELFAIR...TOOMBS...TREUTLEN...TROUP...TWIGGS...UPSON... WARREN...WASHINGTON...WEBSTER...WHEELER...WILCOX...WILKES... WILKINSON. && $$ SHORT TERM...DEESE LONG TERM....11 AVIATION...DEESE
AREA FORECAST DISCUSSION
NWS JACKSON KY
942 PM EDT SUN AUG 18 2013 .UPDATE... ISSUED AT 942 PM EDT SUN AUG 18 2013 THE WIDELY SCATTERED SHOWERS AFFECTING THE AREA DURING THE EVENING HAVE DECREASED IN COVERAGE AT THIS TIME ON THIS SIDE OF THE KY/VA BORDER. TO THE EAST OF THE BORDER...A BAND OF SHOWERS CONTINUES TO ADVANCE NORTHEASTWARD. THESE SHOWERS WILL SKIRT OUR VA BORDER COUNTIES THROUGH THE NIGHT INTO TOMORROW MORNING AND WILL MAINTAIN HIGHEST POPS IN THAT AREA...WITH DIMINISHING RAIN CHANCES TO THE WEST. LATEST HRRR RUN SHOWS SOME SHOWERS DEVELOPING BACK FURTHER TO THE WEST TOWARDS DAWN AND WITH THE FILLING UPPER LOW NEARBY...WILL MAINTAIN AT LEAST A 20 POP EVERYWHERE THROUGH THE NIGHT INTO THE DAY TOMORROW. OTHERWISE...ADDED PATCHY FOG INTO THE FORECAST AS ANY BREAKS IN THE CLOUDS WILL ALLOW IT TO FORM RATHER QUICKLY OVERNIGHT BUT NO OTHER CHANGES WERE NEEDED AT THIS TIME. && .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 220 PM EDT SUN AUG 18 2013 UPPER LOW SPINNING OVER WRN KY WILL CONTINUE TO EASE TO THE EAST AS HIGH PRESSURE SLOWLY RELEASES IT/S HOLD ON THE REGION AND SLIPS TO THE MID ATLANTIC COAST. MEANWHILE A SFC LOW COMING ONSHORE NEAR THE MID GULF COAST CONTINUES TO PUSH MOISTURE AND A BLANKET OF CLOUDS INTO ERN KY. EXPECT THE RAIN TO CONTINUE OVER ERN KY FOR THE NEXT 24-30 HRS AS THE UPPER LOW EDGES ACROSS THE STATE AND FINALLY MOVES NE TOWARDS THE NEW ENG COAST. THE GULF COAST LOW WILL SLOWLY TRACK NE AND LINK UP WITH THE UPPER LEVEL SYSTEM BEFORE SWEEPING INTO THE POCONOS. HIGH PRESSURE WILL THEN BUILD BACK INTO THE AREA AND GIVE THE REGION A SMALL WINDOW TO DRY OUT ON MON NIGHT. BUT THE MOISTURE SPLAYED ACROSS THE AREA TODAY AND TONIGHT WILL SET THE STAGE FOR FOG MON NIGHT AS A FEW BREAKS IN THE CLOUD COVER WILL ALLOW TEMPS TO DROP FROM A MON HIGH AROUND 80 TO LOWS AT OR NEAR THE DEWPOINT TEMPS IN THE LOWER 60S FOR MON NIGHT. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 231 PM EDT SUN AUG 18 2013 MODELS HAVE CHANGED COURSE A BIT GOING INTO TUESDAY AND WEDNESDAY AS ANOTHER MID/UPPER LEVEL LOW WILL DEVELOP OVERHEAD. ON TUESDAY...MOISTURE WILL BE ON THE INCREASE FROM THE SOUTH. MUCH LIKE ON SATURDAY...DOWNSLOPING SOUTHEAST WINDS WILL HAMPER THE NORTHWARD PROGRESS OF ANY PRECIPITATION AND KEEP INSTABILITY AT BAY. THUS...GOING TO CONFINE POPS TO MAINLY THE SOUTHERN 2 ROWS OF COUNTIES IN KENTUCKY WITH ONLY A SLIGHT CHANCE. AREAS FURTHER NORTH WILL LIKELY BE AFFECTED BY THE DOWNSLOPING CONDITIONS. BY TUESDAY NIGHT...AS THE UPPER LEVEL LOW PUSHES SLIGHTLY EAST...WINDS WILL VEER AROUND TO THE SOUTH OR SOUTHWEST ALLOWING MOISTURE TO SURGE NORTHWARD. CLOUDS AND SHOWERS WILL OVERSPREAD THE AREA FROM LATE TUESDAY NIGHT INTO WEDNESDAY. A MID LEVEL VORTICITY MAXIMUM WILL PUSH EAST DURING THE DAY TO AID IN MORE VIGOROUS SHOWER ACTIVITY. STILL SOME QUESTION AS TO INSTABILITY DURING THE DAY...AND MUCH LIKE TODAY...CLOUD COVER COULD LIMIT INSTABILITY KEEPING ANY THUNDER AT BAY. GOING TO CARRY A SLIGHT CHANCE FOR NOW...BUT FEEL THIS THUNDER PROBABLY WILL NOT PAN OUT. THIS SYSTEM WILL FINALLY BE ON THE WAY OUT BY THURSDAY WITH THE EXPECTED RIDGING FINALLY BUILDING ACROSS THE REGION. THIS WILL SET UP THE SUMMER-LIKE PATTERN BY THURSDAY AND THROUGH NEXT WEEKEND. THIS WILL YIELD A MINIMAL CHANCE FOR SHOWERS OR STORMS EACH AFTERNOON...BUT ANTICIPATING THAT MOST AREAS WILL REMAIN DRY FROM WEDNESDAY NIGHT ONWARD. TEMPERATURES WILL REMAIN A TOUCH BELOW NORMAL INTO WEDNESDAY WITH THE CLOUD COVER AND PRECIPITATION...BUT WILL WARM TO NEAR NORMAL FOR THE SECOND HALF OF THE WEEK...AND AT THIS POINT...LOOKING FOR SLIGHTLY ABOVE NORMAL READINGS BY NEXT WEEKEND. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 721 PM EDT SUN AUG 18 2013 BELOW AVERAGE CONFIDENCE IN FORECAST DETAILS FOR AREA AIRPORTS TONIGHT AS CLOUDS ARE EXPECTED TO BREAK UP ENOUGH TO ALLOW FURTHER LOW CLOUD AND FOG DEVELOPMENT LATER TONIGHT WITH AMPLE LOW LEVEL MOISTURE IN PLACE. WILL FORECAST DETERIORATING CONDITIONS AT ALL 3 TAF SITES WITH A PERIOD OF LIFR CIGS/VSBYS AROUND DAWN. SHOULD MID LEVEL CLOUDS HOLD IN THROUGH THE NIGHT...THIS WILL BE TOO PESSIMISTIC. OTHERWISE...A FEW STRAY SHOWERS WILL BE POSSIBLE THIS EVENING AND THEN AGAIN TOMORROW AND WILL HANDLE WITH A VCSH MENTION AT THIS TIME. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...ABE SHORT TERM...DUSTY LONG TERM...KAS AVIATION...ABE
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
207 AM EDT SAT AUG 17 2013 .SYNOPSIS... LOW PRESSURE WILL SLOWLY MOVE NORTHEAST ALONG THE MID ATLANTIC COAST THIS WEEKEND. HIGH PRESSURE RETURNS EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... WILL BE MAKING SIGNIFICANT CHANGES TO THE GRIDS THROUGH 00Z SUN WITH THE 1 AM UPDATE. MAIN CHANGE WILL TO LWR RAIN CHANCES ACROSS THE NRN HALF OF FA AND LIMITING IT TO SAT AFTRN. IT MAY NOT RAIN AT ALL ACROSS THE LW MD ERN SHORE UNTIL SAT EVE. RAIN CHANCES SLOWLY INCRS THROUGH THE DAY ACROSS THE SOUTH. THIS ALL BASED ON LATEST DATA WHERE THE MODELS ARE SHOWING DRYER AIR FROM THE HIGH PRS OVR THE AREA WINNING OUT ACROSS THE FA THRU AT LEAST 18Z. PVS DSCN: UPDATE AS OF 1045 PM EDT...ANOTHER STRANGE EVENING WHERE WX HAS BEEN TRENDING DRIER THAN EXPECTED. A BAND OF CLOUDS IS CURRENTLY MOVING OFF THE COAST AND A BATCH OF RAIN HAS DEVELOPED OVER THE VA TIDEWATER AND NE NC. WILL CONTINUE TO CARRY LIKELY POPS IN THIS AREA THRU EARLY AM AS PCPN EXITS. ELSEWHERE...CLEARING HAS WORKED INTO CENTRAL VA AND WILL CONTINUE TO ADVANCE EAST THRU EARLY AM. THIS CLEARING HAS ALLOWED TEMPS TO FALL A LITTLE LOWER THAN EXPECTED AND THUS HAVE LOWERED OVN LOWS A FEW DEGREES. LOWS IN THE UPR 50S NW TO THE MID 60S SE. THERE IS SOME INDICATION IN THE LATEST IR SATELLITE IMAGERY AND SFC OBS THAT CLOUDS MOVING NORTHWARD THRU CENTRAL NC WILL SPREAD OVER OUR AREA DURING THE PRE-DAWN HOURS SO WILL HAVE CLOUDS RETURNING OVERNIGHT. HOWEVER..QUESTIONS REMAIN AS TO JUST HOW MUCH PCPN WILL PUSH NORTHWARD BY DAYBREAK. LATEST NAM AND HRRR ARE NOT THAT EXCITED ABOUT RAIN GETTING NORTH OF THE HWY 58 IN SOUTHERN VA TIL AFTER 15Z SAT...SO NEXT SHIFT WILL LIKELY BE TRIMMING POPS BACK EVEN FARTHER FOR SAT MORN. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY/... UPPER LEVEL HIGH PRESSURE OVER THE CTRL ATLANTIC SHIFTS TWD THE SE COAST OVER THE WEEKEND. MEANWHILE...AN UPPER TROUGH WILL STAY WELL ROOTED IN THE OH/TN VALLEYS DUE TO AN AMPLIFYING RIDGE OVER THE GREAT BASIN. THE COMBINATION OF THESE UPPER LEVEL FEATURES WITH THE STALLED SFC BOUNDARY ALONG THE CAROLINA COAST WILL CAUSE MOISTURE AND SHORTWAVE ENERGY TO STREAM ACROSS THE MID ATLANTIC REGION SATURDAY THROUGH SUNDAY NIGHT. A CONTINUATION OF FAVORABLE ISENTROPIC LIFT MOVING INTO THE AREA FROM THE SOUTHWEST ON SATURDAY WILL QUICKLY SATURATE THE LOWER ATMOSPHERE AND ACT TO ENHANCE STEADY PRECIPITATION/RAINFALL. PWATS WILL GRADUALLY INCREASE THROUGH THE WEEKEND FROM ROUGHLY 0.75 INCHES NORTH TO 1.50 INCHES SOUTH FOR TONIGHT...TO AROUND 2.00 INCHES NORTH TO 2.35 INCHES SOUTH BY SUNDAY. THE BEST POTENTIAL FOR WIDESPREAD STEADY RAIN IS SATURDAY NIGHT. HOWEVER THE WEEKEND WILL NOT BE A COMPLETE WASHOUT...BUT DO EXPECT PERIODS OF RAIN THAT WILL BE MODERATE TO HEAVY AT TIMES AND MOSTLY CLOUDY TO CLOUDY SKIES. FOR SUNDAY...FORECAST MODELS ARE HINTING AT A DRY SLOT MOVING INTO NE NC AND SE VA DURING THE DAY AS THE ATLANTIC HIGH PUSHES CLOSER TO THE SOUTHEAST COAST. IF THIS OCCURS...THEN THERE COULD BE A NICE REPRIEVE FROM THE RATHER WET WEEKEND RAINS IN THE AFOREMENTIONED AREAS. AT THIS TIME...IT IS DIFFICULT TO PINPOINT EXACTLY WHERE THE DRIER CONDITIONS MAY SET UP AND HAVE THEREFORE KEPT A CHANCE OF PRECIP IN THE ONGOING FORECAST FOR SUNDAY AFTN/EVENING. DUE TO EXTENSIVE CLOUD COVER AND COOLER AMBIENT AIR DUE TO EVAPORATIVE COOLING PROCESSES...TEMPERATURES WILL BE ON THE COOL SIDE WITH HIGHS SAT/SUN GENERALLY IN THE 70S (NEAR 80 NE NC/FAR SE VA ON SUN DUE TO POTENTIAL DRY SLOT/CLEARING). THE LOWS ON SATURDAY NIGHT WILL GENERALLY BE IN THE 60S (NEAR 70 COASTAL NE NC/FAR SE VA). THE OH/TN VALLEY TROUGH AND GREAT BASIN HIGH BOTH BEGIN TO WASH OUT ON MONDAY AND APPEAR TO RESULT IN A PSEUDO-WESTERLY (OR ZONAL) FLOW. AT THIS TIME...IT SHOULD BE ENOUGH TO START PUSHING THE PERSISTENTLY RAINY WX PATTERN OUT OF THE AREA BUT NOT UNTIL TUESDAY/TUESDAY NIGHT. HIGH TEMPERATURES REBOUND INTO THE LOWER 80S SINCE A COMBINATION OF SUN AND CLOUDS ARE ANTICIPATED DURING THE DAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... STRONG UPPER-LEVEL WESTERLY FLOW PREVAILS OVER SOUTHERN CANADA THROUGH THE MIDDLE AND LATER PORTIONS OF NEXT WEEK. UNDERNEATH THIS ZONAL FLOW...MID-LEVEL ANTICYCLONES WILL REMAIN NEARLY STATIONARY OVER THE SOUTHERN PLAINS AND WESTERN ATLANTIC. AN AREA OF (SOMEWHAT) LOWER HEIGHTS IS PROGGED OVER THE APPALACHIAN PLATEAU. HOWEVER...THE MID ATLANTIC REGION SHOULD LARGELY REMAIN UNDER THE INFLUENCE OF THE WESTERN ATLANTIC RIDGE. HENCE... PRECIPITATION POTENTIAL SHOULD BE MINIMAL (NEAR OR BELOW CLIMO) DUE TO A LACK OF LARGE SCALE FORCING FOR STORM ORGANIZATION... DESPITE A WARM AND INCREASINGLY HUMID AIRMASS. HIGH TEMPERATURES SHOULD AVERAGE AROUND SEASONAL NORMALS TUESDAY THROUGH FRIDAY (MID/UPPER 80S)...WITH A FEW 90 DEGREE HIGHS POSSIBLE IN FAVORED HOT SPOTS. LOWS SHOULD PRIMARILY RANGE FROM THE UPPER 60S TO LOW 70S. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... A NEARLY STATIONARY COASTAL FRONT HAS ORIENTED ALONG THE SE COAST AS HIGH PRESSURE REMAINS OVER THE NE STATES. THE RESULT IS CONTINUED NELY ONSHORE FLOW OVER THE LOCAL AREA. VISIBLE ON IR SATELLITE AND SFC OBS...IS A WAVE OF LOW PRESSURE LIFTING ALONG THE FRONT. INCREASING MOISTURE AND THE LIFTING WAVE WILL PROVIDE A BETTER FOCUS FOR SHOWERS BEGINNING THIS MORNING OVER NC AND SPREADING NWD DURING THE DAY. FOR THIS MORNING...MID/HIGH LEVEL CLOUDS WILL CONTINUE TO STREAM IN FROM THE SOUTH. LOW CLOUDS WILL ALSO LIFT FROM NC INTO SE VA/NE NC...RESULTING IN MVFR/LOCALLY IFR CIGS THROUGH 12Z (KECG EXPECTED TO REMAIN IFR THROUGH 12Z). THEREAFTER...EXPECT MIXING TO LIFT LOCALIZED IFR CIGS TO MVFR...WITH MVFR CIGS (1500-2500 FT AGL) THROUGH MUCH OF THE DAY WITH PRECIP. ELSEWHERE ...BKN-OVC SKIES WITH DECKS 4-7K FT AGL EXPECTED IN ADVANCE OF THE LIFTING WAVE. AS PRECIP MOVES IN...CIGS WILL LIKELY FALL TO MVFR (1500-2500 FT AGL) AND REMAIN THROUGH THE TAF PERIOD. EXACT TIMING OF THE PRECIP REMAINS TRICKY ATTM...SO WILL ADJUST TAFS BASED ON LATEST GUIDANCE/TRENDS. WINDS WILL REMAIN OUT OF THE NE-E GENERALLY 10 TO 15 KT. UNSETTLED CONDITIONS WILL CONTINUE THROUGH THE WEEKEND AS THE COASTAL FRONT REMAINS NEARLY STATIONARY. HIGH PRESSURE WILL REMAIN TO THE NORTH WITH NE-E FLOW OVER THE LOCAL AREA. && .MARINE... THE LATEST MSAS SURFACE ANALYSIS SHOWS A 1017MB LOW ~110NM ENE OF CAPE HATTERAS TRACKING NE ALONG A COASTAL FRONT ALIGNED PARALLEL TO THE SOUTHEAST COAST. A NE WIND (STRONGEST OFF THE CURRITUCK OUTER BANKS) IS GRADUALLY DIMINISHING AS THE LOW PULLS AWAY AND HIGH PRESSURE RETURNS FROM THE N. ANOTHER LOW (PRESENTLY OVER SOUTHERN GA) IS PROGGED TO LIFT NE ALONG THE SOUTHEAST COAST TONIGHT THROUGH SATURDAY...EVENTUALLY REACHING THE MID ATLANTIC SATURDAY NIGHT AND SUNDAY...BEFORE PULLING TO THE NE SUNDAY NIGHT. THIS PATTERN WILL MAINTAIN A PERSISTENT NE FLOW OVER THE REGION THROUGH SATURDAY NIGHT FOR THE ENTIRE AREA...AND INTO SUNDAY FOR THE NORTHERN PORTION OF THE MARINE AREA. WIND SPEEDS REMAIN CAPPED AROUND 15KT ALONG WITH SEAS/WAVES CAPPED AT 4FT/3FT. CONFIDENCE ON SCA HEADLINES REMAINS LOW...SO NO FLAGS WILL BE ISSUED. ALTHOUGH A FEW BRIEF PERIODS OF SCA WIND ARE POSSIBLE ACROSS THE LOWER BAY (4FT WAVES MOUTH OF THE BAY)...AND 5FT SEAS ARE POSSIBLE OUT NEAR 20NM IN THE OCEAN. HIGH PRESSURE RETURNS EARLY NEXT WEEK WITH LIGHT SSW FLOW RETURNING...ALONG WITH 2-3FT SEAS. PERSISTENT ONSHORE FLOW WILL RESULT IN AN ELEVATED RIP CURRENT RISK SATURDAY AND POSSIBLY INTO SUNDAY AS WELL. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...MODERATE RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH THIS EVENING FOR MDZ025. NC...MODERATE RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH THIS EVENING FOR NCZ102. VA...MODERATE RIP CURRENT RISK FROM 8 AM EDT THIS MORNING THROUGH THIS EVENING FOR VAZ098>100. MARINE...NONE. && $$ SYNOPSIS...BMD NEAR TERM...JDM/MPR SHORT TERM...BMD LONG TERM...AJZ AVIATION...SAM MARINE...AJZ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
739 PM EDT SUN AUG 18 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 409 PM EDT SUN AUG 18 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE OVER THE SRN U.S. ROCKIES WITH A TROF LINGERING OVER THE LWR MISSISSIPPI VALLEY. TO THE N...ZONAL FLOW DOMINATES SRN CANADA. THERE ARE A COUPLE OF SHORTWAVES OF INTEREST UPSTREAM IN THIS ZONAL FLOW. THE FIRST IS OVER SE MANITOBA...AND THE SECOND IS OVER SRN SASKATCHEWAN/ERN MT. THE FIRST WAVE IS GENERATING CONVECTION OVER FAR SE MANITOBA INTO ADJACENT NRN ONTARIO. THE SECOND WAVE IS GENERATING SCT SHRA/TSRA OVER THE WRN DAKOTAS INTO SRN SASKATCHEWAN. CLOSER TO HOME...12Z SOUNDINGS FROM KGRB/KMPX SHOWED VERY DRY MID LEVELS AND A HEALTHY CAP...AND THUS NO PCPN IS OCCURRING OVER THE FCST AREA THIS AFTN. SOME CI AND A RATHER THICK ELEVATED SMOKE LAYER HAS HELD TEMPS DOWN A BIT FROM EXPECTATIONS WITH READINGS MOSTLY IN THE UPPER 70S TO LOW 80S AS OF 19Z. NEAR LAKE MICHIGAN...SOUTHERLY WINDS OFF THE LAKE ARE HOLDING TEMPS TO THE LOW/MID 70S. AFTER A DRY START TO THE SHORT TERM...ATTENTION TURNS TO THE POTENTIAL OF SHRA/TSRA LATE TONIGHT/MON AS THE PAIR OF SHORTWAVES CURRENTLY OVER SE MANITOBA AND OVER SRN SASKATCHEWAN/ERN MT MOVES EASTWARD. INITIAL DRY/CAPPED AIR MASS WILL ENSURE DRY WEATHER ACROSS THE FCST AREA THIS EVENING. THEN...SW FLOW AHEAD OF SHORTWAVES WILL TRANSPORT INTO THE UPPER LAKES THE MORE HUMID AIR MASS EVIDENT OVER THE CNTRL PLAINS THIS MORNING PER 12Z RAOBS. WHILE THE ANTECEDENT DRY AIR WILL WORK TO DELAY SHRA...DEGREE OF MOISTENING/MAGNITUDE OF THETA-E ADVECTION SUGGESTS THERE WILL BE SOME RISK OF PCPN. THERE MAY BE 2 RATHER DISTINCT CLUSTERS OF SCT SHRA/TSRA. THE FIRST ASSOCIATED WITH THE SE MANITOBA SHORTWAVE COULD REACH NW LAKE SUPERIOR/ISLE ROYALE AREA EARLY IN THE OVERNIGHT. 850-300MB THICKNESS FIELD SUGGESTS SOME OF THE CURRENT SHRA/TSRA ASSOCIATED WITH THE WAVE MAY TAKE A SHARP TURN TO THE RIGHT AS THEY APPROACH THE LAKE...SO IT REMAINS TO BE SEEN WHERE THESE SHRA MAY END UP. THE SECOND AREA OF CONVECTION MAY DEVELOP ACROSS NRN MN TOWARD WRN LAKE SUPERIOR LATE IN THE NIGHT OR MON MORNING WITH THE FOLLOWING SHORTWAVE. IN BOTH CASES...THERE IS AN INDICATION OF WEAKENING MOISTURE TRANSPORT EASTWARD WITH TIME...SO SHRA WILL PROBABLY BE ON A DIMINISHING TREND AS THEY MOVE TOWARD LAKE SUPERIOR/UPPER MI. AT THIS POINT...SEE NO REASON TO DEVIATE MUCH FROM INHERITED FCST WHICH BROUGHT CHC POPS TO WRN LAKE SUPERIOR OVERNIGHT AND SCHC POPS TO WRN UPPER MI LATE. INCREASING COLUMN MOISTURE AND STIRRING S TO SW WINDS WILL WORK TO KEEP TEMPS HIGHER THAN LAST NIGHT. EXPECT MINS IN THE MID 60S IN THE DOWNSLOPE AREAS NEAR LAKE SUPERIOR. MINS IN THE MID 50S TO PERHAPS AS LOW AS 50F IN TRADITIONAL COLD SPOTS SHOULD BE THE RULE INLAND. ON MON...SHORTWAVE TROF MOVES ACROSS THE UPPER LAKES...BUT WILL BE WEAKENING AS EVIDENT IN HEIGHT FIELD AND DEEP LAYER FORCING PER QVECTORS. IF ANY SHRA/TSRA REACH THE W LATE TONIGHT...THEY WILL LIKELY WEAKEN IN THE MORNING. DURING THE AFTN...MLCAPE IS FCST TO INCREASE TO POSSSIBLY AS MUCH AS 800-1000J/KG. HOWEVER...WITH DIMINISHING FORCING AND POTENTIALLY LITTLE IN THE WAY OF LAKE BREEZE CONVERGENCE...COVERAGE OF ANY DIURNALLY DRIVEN CONVECTION WILL PROBABLY BE QUITE LIMITED. WILL MAINTAIN JUST SCHC POPS FOR THE AFTN HRS. MAX TEMPS SHOULD GENERALLY BE IN THE MID 80S PER FCST SOUNDINGS. OF COURSE...SOUTHERLY WINDS WILL KEEP AREAS NEAR LAKE MICHIGAN A LITTLE COOLER. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 409 PM EDT SUN AUG 18 2013 STARTING OUT ON MONDAY EVENING THE UPPER AIR PATTERN LOOKS ZONAL WITH WEAK TROUGHING OVER THE GREAT LAKES AND A RIDGE CENTERED OVER THE SOUTHWEST CONUS. RIDGE WILL HAVE HARD TIME AMPLIFYING FARTHER NORTH INTO CANADA THIS WEEK THOUGH AS STRONGER WESTERLIES H5-H3 STREAM ACROSS SOUTHERN TIER OF CANADA OUT OF A MORE OR LESS PERSISTENT TROUGH SET UP OVER GULF OF ALASKA. EVENTUALLY...WEDNESDAY NIGHT INTO THURSDAY...LARGER SCALE HEIGHTS FALL SOME AS STRONGER SHORTWAVE/JET MAX...PART OF WHICH IS STREAMING TOWARD WESTERN SHORE OF BRITISH COLUMBIA TODAY...DIGS ACROSS NORTHERN ONTARIO TO WESTERN QUEBEC. SFC COLD FRONT CROSSES UPPER LAKES WEDNESDAY AFTN INTO WEDNESDAY NIGHT JUST AHEAD OF BETTER HEIGHT FALLS BEGIN LATE WEDNESDAY. FRONT REPRESENTS BEST CHANCE OF SHRA/TSRA THIS WEEK. HIGH PRESSURE BUILDS IN BEHIND THE FRONT...BUT QUESTION OF THE DAY IS FOR HOW LONG. THIS WILL HAVE IMPACT ON FORECAST FOR FRIDAY THROUGH NEXT WEEKEND. INITIAL SHORTWAVE THAT ROLLS ACROSS UPPER LAKES ON MONDAY WILL MAINLY BE EAST OF CWA MONDAY EVENING. SOUNDINGS SHOW PERHAPS MID CLOUDS THROUGH THE NIGHT BUT WITH SUBSIDENCE IN WAKE OF WAVE...NOT EXPECTING ANY SHRA/TSRA. ANOTHER WARM NIGHT IN THE 60S WITH STEADY SW SFC WINDS BENEATH STRONGER WINDS AT 950-925MB. STRONGER WINDS ALOFT FADE BY TUESDAY AFTN WHICH MAY RESULT IN LOCALIZED BACKING OF WINDS/LAKE BREEZE ALONG LK SUPERIOR NCNTRL. LAKE MODIFICATION ONLY ALONG LK MICHIGAN ELSEWHERE. MID CLOUDS MAY DAMPEN SUN INITIALLY... BUT SHOULD SEE FULL SUN FOR A WHILE BTWN MID MORNING AND MID AFTN ALLOWING TEMPS TO WARM WELL INTO THE 80S AND PROBABLY TO THE LOWER 90S IN SOME WESTERN CWA LOCATIONS. WILL HAVE TO REACH AT LEAST MID 80S BEFORE CU BEGINS TO FORM AND CONVECTIVE TEMPS ARE ON THE HIGH SIDE IN THE LOWER 90S. SUPPOSE ALONG THE CONVERGENCE OF LAKE BREEZE THERE COULD BE AN ISOLD STORM GIVEN MLCAPES OVER 2000J/KG. MOISTURE THAT IS AROUND PER SOUNDINGS IS VERY SHALLOW SO WITHOUT MUCH ADDITIONAL LARGE SCALE SUPPORT...THINK CHANCES ARE VERY MINIMAL. IF A STORM CAN FORM...WOULD HAVE POTENTIAL FOR GUSTY WINDS AS DCAPE VALUES ARE OVER 1000J/KG. SOUNDINGS POINT TO QUIET...WARM AND HUMID CONDITIONS TUESDAY NIGHT IN THE WARM SECTOR. MAY SEE A TOUCH OF FOG...THOUGH SOME WIND JUST OFF THE SFC WILL LIMIT THE EXTENT. MOIST ONSHORE FLOW MAY LEAD TO MORE FOG CLOSER TO LK MICHIGAN SHORE. WARM WEATHER CONTINUES ON WEDNESDAY. AFTER A WARM START NEAR 70 DEGREES IN SOME SPOTS IT WILL NOT TAKE MUCH TO SEE READINGS REACH THOSE SIMILAR TO TUESDAY. COLD FRONT MAKES IT TO MN ARROWHEAD JUST TO WEST OF DLH BY MIDDAY SO A LOT OF TIME FOR WARMING IN A CAPPED AIRMASS WITH WARM NOSE AROUND 800MB. SOUNDINGS THROUGH 00Z THURSDAY LOOK PRETTY DRY WHICH MAKES SENSE AS PRIMARY SHORTWAVE AND MOISTURE ADVECTION IS NORTH OVR ONTARIO. SW WINDS COULD INCREASE THROUGH THE DAY AS 950-925MB WINDS INCREASE. STILL THINK TEMPS ON WEDNESDAY MAY END UP A BIT WARMER THAN TUESDAY WITH LATER ARRIVAL TO FRONT AND AS H85 TEMPS ARE NEAR +20C TO START THE DAY. DOWNSLOPE MAY LEAD TO FURTHER WARMING ALONG LK SUPERIOR FROM ONTONAGON TO MUNISING. WILL BUMP TEMPS INTO UPR 80S ON AVERAGE AND PUSH DOWNSLOPE AREAS TO AROUND 90. INSTABILITY OBVIOUSLY PRESENT AHEAD OF FRONT WITH THE VERY WARM TEMPERATURES AND INCREASE IN BLYR MOISTURE /DWPNTS ARE WELL INTO THE 60S/. RESULT IS MLCAPES 1500-2000J/KG JUST AHEAD OF THE FRONT. THINK QUALITY OF MOISTURE ULTIMATELY WILL LIMIT CONVECTION COVERAGE WITH THE FROPA. GIVEN THE INSTABILITY AND DEEP LAYER SHEAR UP TO 30 KTS THERE IS AT LEAST A MARGINAL POTENTIAL FOR ISOLD SVR STORMS THROUGH WEDNESDAY EVENING. HIGHER FREEZING LEVEL OVER 14KFT AND DRY AIR ALOFT /DCAPE OVER 1000J/KG/ POINTS TO STRONG WIND GUSTS AS MAIN HAZARD. GOOD AGREEMENT THAT STRONG DRYING/SUBSIDENCE ENDS ANY SHRA/TSRA OVERNIGHT WEDNESDAY NIGHT WITH THURSDAY STILL LOOKING MUCH COOLER AND MAINLY DRY AS HIGH PRESSURE BUILDS ACROSS UPPER GREAT LAKES. GUSTY NORTH TO NORTHWEST WINDS ALONG WITH COLD AIR ADVECTION SHOULD KICK UP WINDS AND WAVES ON LK SUPERIOR LEADING TO ELEVATED SWIM RISK. TEMPS WILL STRUGGLE TO 70 DEGREES NEAR LK SUPERIOR AND COULD REACH LOWER 80S FAR SOUTH. EVEN THOUGH THURSDAY IS AGREED UPON FOR COOLER AND MAINLY DRY WEATHER THE FORECAST FOR THURSDAY NIGHT INTO FRIDAY NOT NEARLY AS CLEAR CUT. GFS MAINTAINS CONTINUITY WITH RECENT RUNS BY SHOWING SPRAWLING HIGH SHUNTING MAIN FRONTAL BOUNDARY AND FOCUS FOR RETURN FLOW SHRA/TSRA OVER THE NORTHERN PLAINS AND OHIO VALLEY UNTIL AT LEAST SATURDAY NIGHT. MEANWHILE...ECMWF UP TO 12Z RUN TODAY WAS CONSISTENT SINCE 00Z RUN ON 17 AUG INDICATING ONLY A BRIEF HIGH PRESSURE INTRUSION. ECMWF THEN SHOWS NEXT SHORTWAVE IN WESTERLY FLOW FORMING A STRONGER SFC-H85 LOW OVER THE NORTHERN PLAINS THURSDAY WITH ASSOCIATED WARM AIR ADVECTION SHRA/TSRA IMPACTING UPPER LAKES AS EARLY AS THURSDAY NIGHT AND FRIDAY. ECMWF CERTAINLY ON THE AMPLIFIED SIDE COMPARED TO ECMWF ENSEMBLE WHICH LOOKS MORE LIKE THE OPERATIONAL GFS. LATEST ECMWF HAS BACKED AWAY FROM THIS IDEA THOUGH JUST ADDING MORE UNCERTAINTY TO THIS TIME FRAME. DROPPED POPS FOR THU NIGHT AND FRIDAY TO SLIGHT CHANCE...BUT WANTED TO KEEP SOME POPS IN THERE IN CASE MODELS SHIFT BACK TO WETTER IDEA. MUDDLED FORECAST CONTINUES THROUGH NEXT WEEKEND AS TIMING FOR SYSTEMS MOVING THROUGH REST OF THE WEEKEND IS STILL OUT OF WHACK BTWN THE GFS AND ECMWF. CONSENSUS APPROACH WORKS FOR NOW UNTIL THESE DETAILS CAN BE BETTER SORTED OUT. AFTER THE COOLER TEMPS THURSDAY AND FRIDAY...SEEMS THAT TEMPS WILL REACH BACK TOWARD NORMAL AND MAYBE EVEN ABOVE NORMAL IF THERE IS NOT MUCH IN WAY OF CLOUDS OR PRECIPITATION. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z MONDAY EVENING) ISSUED AT 737 PM EDT SUN AUG 18 2013 WITH SW FLOW OF RELATIVELY DRY AIR...EXPECT VFR CONDITIONS TO PREVAIL THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. INCREASING SW WINDS ABOVE NOCTURNAL INVERSION TONIGHT WILL APPROACH LLWS CRITERIA. ALSO A DISTURBANCE APPROACHING FROM THE W MAY BRING ISOLD/SCT CONVECTION INTO UPPER MI LATE TONIGHT THRU MON MORNING. HOWEVER...AT THIS POINT...CONFIDENCE IS VERY LOW ON ACTUAL OCCURRENCE OF CONVECTION LET ALONG LOCATION/COVERAGE. THUS...NO MENTION OF SHRA/TSRA WAS INCLUDED IN THIS FCST ISSUANCE. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 409 PM EDT SUN AUG 18 2013 OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE GREAT LAKES REGION. SOME STRONGER SW WIND GUSTS UP TO 20-25KT MAY OCCUR TONIGHT UNDER A SHARPER PRES GRADIENT AHEAD OF AN APPROACHING DISTURBANCE. THE ARRIVAL OF MORE HUMID AIR FOR TUE/WED MAY RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL BE MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE. ANY FOG WILL DISSIPATE THU FOLLOWING A COLD FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLA AVIATION...VOSS MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS GREAT FALLS MT
1040 PM MDT Fri Aug 16 2013 AVIATION SECTION UPDATED .DISCUSSION... Update forthcoming. Have made minor changes to the sky grids. Have also expanded pop area over the extreme northwest portion of the county warning area. HRRR analysis brings very light precipitation to the area toward daybreak, likely associated with area of clouds moving through the Idaho panhandle at this time. Temperatures look reasonable. Emanuel && .AVIATION... UPDATED 0440Z. Current satellite imagery shows weak upper level trough stretching from southeast Alberta to the ID Panhandle moving faster and bringing greater cloud coverage than forecast models had been indicating. Not a big impact given that ceilings should remain above 10000 ft, but enough to adjust cloud timing and coverage in latest KCTB/KGTF/KHVR TAFs. Have also added mention of VCTS vcnty KCTB tomorrow aftn. Elsewhere, smoke from wildland fires in the western portion of Montana and from eastern Idaho will keep thin layers of high clouds over central and southwest MT overnight and much of tomorrow. Surface winds remaining light through the overnight hours. Waranauskas && .PREV DISCUSSION...Issued 230 PM MDT Fri Aug 16 2013 Tonight through Sunday...Warm and dry conditions will continue Friday afternoon into Saturday. High pressure slowly begins to shift east in response to a weak mid level boundary passing through the region early Saturday. There will be a slight chance of some afternoon shower development over portions Central Montana Saturday and Sunday but dry lower level conditions may prevent most precipitation reaching the ground. Elevated terrain will likely have a better chance of seeing any precipitation from anything that does develop. Any storms that do develop will likely only produce gusty winds near their vicinity. Fire weather conditions are marginal at this time but very low relative humidity and afternoon breeziness add to the danger level. For additional fire weather concerns please see the Fire Weather Discussion. Temperatures look to moderate slightly over the weekend with highs dropping to the upper 80s and low 90s. Sunday night through Friday...The zones will be underneath a flat upper level high pressure ridge Sunday night and the airmass will be quite dry. The next low pressure weather system will be well west over the Eastern Pacific. The upper level ridge will move east of the zones by Tuesday afternoon and flow aloft will switch to the southwest. Moisture will again be able to move underneath the ridge and the airmass will become unstable again Wednesday afternoon, mainly over the southwest zones. Later in the week latest model runs indicate that the upper ridge will rebuild and affect the forecast area. Therefore have updated the forecast to go with warmer temperatures. There is the possibility that high temperatures could return to near 90 by late in the week for the lower elevations. Even with this change to a rebuilding upper ridge it still looks like there could be some instability so will continue with the mention of a slight chance of thunderstorms even though some guidance from the models indicates Thursday and Friday could be dry. Blank && .FIRE WEATHER... UPDATED 2030Z. Critical fire weather conditions remain possible into Friday evening before returning Saturday afternoon over Southwest and South Central Montana. Afternoon humidity will drop to very low values of 5 to 10 percent across the lower elevations with slightly higher values of 10 to 15 percent Saturday. A weak mid- level boundary passing through the region Saturday afternoon could bring somewhat breezy westerly winds, mainly along and near the Continental Divide. Not expecting a major wind shift or strong winds from these boundaries though. Breezy winds combined with low humidity could result in critical fire weather conditions Saturday afternoon. Confidence remains high for humidity less than 20 percent and around 50 percent for winds over 15 mph Saturday. As a result, will hold off on fire weather highlights at this time. && .PRELIMINARY POINT TEMPS/POPS... GTF 57 91 57 89 / 10 10 30 10 CTB 56 85 53 83 / 10 10 10 0 HLN 59 90 58 89 / 0 20 20 10 BZN 51 90 51 88 / 0 10 20 10 WEY 39 83 42 81 / 0 10 10 20 DLN 51 87 50 86 / 0 10 10 10 HVR 60 89 59 88 / 10 10 30 20 LWT 55 87 56 85 / 0 10 30 20 && .TFX WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING until 9 PM MDT this evening Beaverhead... Central and Southern Lewis and Clark...Jefferson...Madison. && $$ weather.gov/greatfalls
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1230 PM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 555 AM CDT SAT AUG 17 2013 HELD OFF AS LONG AS WE COULD...BUT KUEX NOW INDICATES ISOLATED SHOWER ACTIVITY DEVELOPING OVER ROOKS COUNTY. MEAGER ELEVATED POTENTIAL INSTABILITY IS ALSO SUGGESTED BY RAP ANALYSIS PROXIMITY SOUNDINGS AND THUS...OCCASIONAL LIGHTNING/THUNDER ALSO CANNOT BE RULED OUT. WENT AHEAD WITH 20% POPS UNTIL 13Z FOR OUR EXTREME SOUTHWESTERN CWA. THE LOW LEVEL JET SHOULD QUICKLY DIMINISH POST- SUNRISE THUS ALLOWING FOR DIMINISHING SHOWER AND THUNDERSTORM ACTIVITY. REMAINDER OF THE FORECAST WAS LEFT UNCHANGED. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 346 AM CDT SAT AUG 17 2013 OVERNIGHT MAP ANALYSIS INDICATES MID TO UPPER LEVEL LONGWAVE RIDGING OVER THE WESTERN CONUS...WITH A TROUGH OVER THE EAST. MID TO UPPER LEVEL JET ENERGY EXTENDS FROM THE WEST-CENTRAL CONUS...NORTHEAST INTO SOUTHWEST AND SOUTH CENTRAL CANADA...AND THEN SOUTHEAST ACROSS THE PLAINS...AND FINALLY EAST/NORTHEAST ACROSS THE SOUTHEASTERN CONUS AND ON INTO THE EASTERN CONUS. MID TO UPPER LEVEL FLOW OVER THE CENTRAL PLAINS REMAINS FROM THE NORTH/NORTHWEST AS A RESULT...BUT IS NOT PARTICULARLY STRONG ONLY MAXING OUT AT AROUND 45KTS NEAR 200MB PER 00Z SOUNDING DATA FROM KLBF AND KOAX. WATER VAPOR IMAGERY ALSO SHOWS THE AFOREMENTIONED LONGWAVE RIDGE AND TROUGH...WITH INCREASED VALUES OF MID LEVEL MOISTURE FLOWING ALONG THE MID LEVEL JET AXIS. AT THE SURFACE A LARGE AREA OF HIGH BAROMETRIC PRESSURE EXISTS OVER THE MISSOURI AND MID MISSISSIPPI RIVER VALLEYS. LOW LEVEL FLOW ACROSS OUR AREA REMAINS FROM THE SOUTHEAST AS A RESULT. LOW LEVEL THERMAL ADVECTION ALONG THE AXIS OF A ~30KT 850MB JET AXIS IS HELPING PROMOTE ISOLATED SHOWER AND THUNDERSTORM ACTIVITY OVER PORTIONS OF WESTERN KANSAS THIS MORNING. ALTHOUGH THIS ACTIVITY HAS REMAINED SOUTHWEST OF OUR CWA SO FAR TONIGHT...GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF- MEAN ALL SUGGEST THE LOW LEVEL JET STREAK AXIS WILL VEER MORE INTO OUR AREA TOWARDS 12Z. THE NAM AND EC BOTH SUGGEST LIGHT PRECIPITATION WILL BE REALIZED OVER EXTREME SOUTHWESTERN PORTIONS OF OUR CWA...A SOLUTION ALSO SUPPORTED TO AN EXTENT BY THE HRRR AND 1KM WRF-NMM. ALL THAT BEING SAID...CONFIDENCE OF ANY ONE LOCATION ACROSS OUR CWA...INCLUDING OUR SOUTHWESTERN CWA...ACTUALLY OBSERVING MEASURABLE RAINFALL REMAINS VERY LOW AND AS A RESULT...WILL CONTINUE WITH THE DRY FORECAST FOR EARLY THIS MORNING AND CONTINUE TO MONITOR. FOR THE REST OF TODAY AND TONIGHT...AN OVERALL LACK IN KINEMATIC FORCING SHOULD PRESENT DRY CONDITIONS TO OUR AREA THROUGH TONIGHT. MUCH LIKE THIS MORNING HOWEVER...THE ONLY EXCEPTION COULD BE ACROSS OUR WEST/SOUTHWEST 06-12Z SUNDAY AS THE AXIS OF ~30KT 850MB JET STREAK ONCE AGAIN DEVELOPS OVER PORTIONS OF THE CENTRAL HIGH PLAINS. THAT BEING SAID...QPF FIELDS FROM VARIOUS MODELS DO NOT SUGGEST MEASURABLE PRECIPITATION WILL BE REALIZED ANYWHERE ACROSS OUR CWA AND GIVEN THIS...WILL GO AHEAD AND MAINTAIN A DRY FORECAST THROUGH 12Z SUNDAY AND LET FUTURE SHIFTS REEVALUATE THE POTENTIAL NEED FOR LOW POPS DURING THE EARLY MORNING HOURS ON SUNDAY. CLOUD COVER REALLY KEPT TEMPERATURES ACROSS OUR CWA ON THE COOL SIDE DURING THE DAY FRIDAY. THE STRATUS DECK HAS NOT BEEN NEARLY AS DENSE AS EXPECTED TONIGHT HOWEVER AND THE CURRENT THINKING IS THIS STRATUS SHOULD DISSIPATE AND LIFT BY MID TO LATE MORNING WHICH SHOULD ALLOW FOR WARMER AFTERNOON HIGHS. GUIDANCE FROM THE MET...MAV...AND ECS SEEMS TO HAVE A GOOD HANDLE ON THIS AND TAKING AN EVEN AVERAGE OF THE THREE PROVIDES AFTERNOON HIGH TEMPERATURES IN THE UPPER 70S TO NEAR 80 ACROSS MUCH OF THE CWA. CLEARER SKIES SHOULD ALLOW FOR A SLIGHTLY COOLER OVERNIGHT LOWS TONIGHT WHEN COMPARED TO EARLY THIS MORNING...WITH OVERNIGHT LOWS IN THE UPPER 50S TO NEAR 60 CURRENTLY FORECAST FOR MOST LOCATIONS TONIGHT. FINALLY...NEAR-ZERO LOW LEVEL DEW POINT DEPRESSIONS AND A FAIRLY LIGHT SOUTH/SOUTHEAST LOW LEVEL WIND FIELD COULD PROMOTE PATCHY FOG ACROSS THE AREA TOWARDS SUNRISE SUNDAY. VISIBILITY RESTRICTION IS NOT EXPECTED TO BE SIGNIFICANT...BUT WILL GO AHEAD WITH PATCHY FOG IN THE GRIDS BEGINNING 09Z SUNDAY. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 346 AM CDT SAT AUG 17 2013 A RELATIVELY QUIET WEATHER PATTERN WILL BECOME EVIDENT BEGINNING SUNDAY AS HIGH PRESSURE CONTINUES TO SLIDE OVER THE REGION FROM THE INTERMOUNTAIN WEST. WATER VAPOR IMAGERY DEPICTS A 500MB TROUGH OVER THE EASTERN PART OF THE CONUS...WHILE HIGH PRESSURE IS BUILDING IN OVER MOST OF THE WESTERN CONUS. THERE IS A SHORT WAVE TROUGH EVIDENT OVER THE PACIFIC NORTHWEST AS WELL. MODELS ARE IN GOOD AGREEMENT WITH REGARDS TO HIGH PRESSURE BUILDING IN FROM THE WEST TO CONTINUE. THIS PATTERN WILL MAKE FOR WARMER DAYS AHEAD WITH TEMPERATURES FORECAST TO BE MORE SEASONABLE THAN THE PREVIOUS WEEK. THE PATTERN OVER THE NEXT WEEK IS SHOWING UNFAVORABLE CONDITIONS FOR ANY PRECIPITATION AND HENCE A DRY FORECAST THROUGH MOST OF THE EXTENDED AS HIGH PRESSURE DOMINATES THE REGION. THURSDAY NIGHT INTO FRIDAY APPEARS TO BE THE ONLY DAY SHOWING ANY CHANCE FOR PRECIPITATION...BUT THE LATEST RUNS OF THE GFS AND EC ARE BOTH BEGINNING TO SHOW DRY CONDITIONS IN THE EXTENDED. SINCE THIS IS THE FIRST RUN OF THE EC AND GFS AGREEING IN FAVOR OF DRIER CONDITIONS...I WILL LEAVE THE SLIGHT CHANCES IN THERE FOR THURSDAY NIGHT INTO FRIDAY UNTIL SOME CONSISTENCY EVOLVES. DONT WANT A FLIP FLOP SCENARIO DEVELOPING. I CAN SEE THESE POPS GETTING YANKED IF THIS TREND CONTINUES INTO DAY SHIFT THOUGH. SEEMS VERY REASONABLE TO HAVE THE DRY FORECAST BASED ON THE HIGH PRESSURE STILL PROGGED TO BE NEARLY CENTERED OVER THE CENTRAL PLAINS REGION COME FRIDAY. WITH THE HELP OF HIGH PRESSURE BUILDING IN OVER THE REGION...TEMPERATURES WILL BE MORE SEASONABLE THROUGH THE EXTENDED. SUNDAY WILL BE THE COOLEST DAY OVER THE FORECAST PERIOD...WITH HIGHS RANGING FROM THE LOWER 80S TO UPPER 80S. MONDAY WILL BE SLIGHTLY WARMER. BUT BY TUESDAY...HIGH TEMPERATURES NEAR 90 DEGREES WILL BE THE NORM THROUGH AT LEAST FRIDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1221 PM CDT SAT AUG 17 2013 WILL CONTINUE TO SEE THE POTENTIAL FOR SOME LOWER LEVEL/MVFR CLOUD COVER TO AFFECT THE TERMINAL AREA THROUGH THE AFTERNOON HOURS...BUT IT DOESNT LOOK TO BE A SOLID DECK SO WILL KEEP AS A TEMPO MENTION...AND CEILINGS SHOULD LIFT AS WE GET TOWARD LATER THIS AFTERNOON. MODELS SHOWING THE REDEVELOPMENT OF STRATUS TONIGHT BEING WEST OF THE TERMINAL...SO HAVE THE OVERNIGHT HOURS INTO TOMORROW VFR AT THIS POINT. WINDS THROUGH THE TAF PERIOD WILL REMAIN SOUTHERLY...AS THE AREA SITS BETWEEN HIGH PRESSURE FROM ERN NEB UP INTO THE NERN CONUS...AND LOW PRESSURE OVER THE ROCKIES/HIGH PLAINS. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...BRYANT SHORT TERM...BRYANT LONG TERM...GUERRERO AVIATION...ADO
AREA FORECAST DISCUSSION
NWS HASTINGS NE
555 AM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 555 AM CDT SAT AUG 17 2013 HELD OFF AS LONG AS WE COULD...BUT KUEX NOW INDICATES ISOLATED SHOWER ACTIVITY DEVELOPING OVER ROOKS COUNTY. MEAGER ELEVATED POTENTIAL INSTABILITY IS ALSO SUGGESTED BY RAP ANALYSIS PROXIMITY SOUNDINGS AND THUS...OCCASIONAL LIGHTNING/THUNDER ALSO CANNOT BE RULED OUT. WENT AHEAD WITH 20% POPS UNTIL 13Z FOR OUR EXTREME SOUTHWESTERN CWA. THE LOW LEVEL JET SHOULD QUICKLY DIMINISH POST- SUNRISE THUS ALLOWING FOR DIMINISHING SHOWER AND THUNDERSTORM ACTIVITY. REMAINDER OF THE FORECAST WAS LEFT UNCHANGED. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 346 AM CDT SAT AUG 17 2013 OVERNIGHT MAP ANALYSIS INDICATES MID TO UPPER LEVEL LONGWAVE RIDGING OVER THE WESTERN CONUS...WITH A TROUGH OVER THE EAST. MID TO UPPER LEVEL JET ENERGY EXTENDS FROM THE WEST-CENTRAL CONUS...NORTHEAST INTO SOUTHWEST AND SOUTH CENTRAL CANADA...AND THEN SOUTHEAST ACROSS THE PLAINS...AND FINALLY EAST/NORTHEAST ACROSS THE SOUTHEASTERN CONUS AND ON INTO THE EASTERN CONUS. MID TO UPPER LEVEL FLOW OVER THE CENTRAL PLAINS REMAINS FROM THE NORTH/NORTHWEST AS A RESULT...BUT IS NOT PARTICULARLY STRONG ONLY MAXING OUT AT AROUND 45KTS NEAR 200MB PER 00Z SOUNDING DATA FROM KLBF AND KOAX. WATER VAPOR IMAGERY ALSO SHOWS THE AFOREMENTIONED LONGWAVE RIDGE AND TROUGH...WITH INCREASED VALUES OF MID LEVEL MOISTURE FLOWING ALONG THE MID LEVEL JET AXIS. AT THE SURFACE A LARGE AREA OF HIGH BAROMETRIC PRESSURE EXISTS OVER THE MISSOURI AND MID MISSISSIPPI RIVER VALLEYS. LOW LEVEL FLOW ACROSS OUR AREA REMAINS FROM THE SOUTHEAST AS A RESULT. LOW LEVEL THERMAL ADVECTION ALONG THE AXIS OF A ~30KT 850MB JET AXIS IS HELPING PROMOTE ISOLATED SHOWER AND THUNDERSTORM ACTIVITY OVER PORTIONS OF WESTERN KANSAS THIS MORNING. ALTHOUGH THIS ACTIVITY HAS REMAINED SOUTHWEST OF OUR CWA SO FAR TONIGHT...GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...AND SREF- MEAN ALL SUGGEST THE LOW LEVEL JET STREAK AXIS WILL VEER MORE INTO OUR AREA TOWARDS 12Z. THE NAM AND EC BOTH SUGGEST LIGHT PRECIPITATION WILL BE REALIZED OVER EXTREME SOUTHWESTERN PORTIONS OF OUR CWA...A SOLUTION ALSO SUPPORTED TO AN EXTENT BY THE HRRR AND 1KM WRF-NMM. ALL THAT BEING SAID...CONFIDENCE OF ANY ONE LOCATION ACROSS OUR CWA...INCLUDING OUR SOUTHWESTERN CWA...ACTUALLY OBSERVING MEASURABLE RAINFALL REMAINS VERY LOW AND AS A RESULT...WILL CONTINUE WITH THE DRY FORECAST FOR EARLY THIS MORNING AND CONTINUE TO MONITOR. FOR THE REST OF TODAY AND TONIGHT...AN OVERALL LACK IN KINEMATIC FORCING SHOULD PRESENT DRY CONDITIONS TO OUR AREA THROUGH TONIGHT. MUCH LIKE THIS MORNING HOWEVER...THE ONLY EXCEPTION COULD BE ACROSS OUR WEST/SOUTHWEST 06-12Z SUNDAY AS THE AXIS OF ~30KT 850MB JET STREAK ONCE AGAIN DEVELOPS OVER PORTIONS OF THE CENTRAL HIGH PLAINS. THAT BEING SAID...QPF FIELDS FROM VARIOUS MODELS DO NOT SUGGEST MEASURABLE PRECIPITATION WILL BE REALIZED ANYWHERE ACROSS OUR CWA AND GIVEN THIS...WILL GO AHEAD AND MAINTAIN A DRY FORECAST THROUGH 12Z SUNDAY AND LET FUTURE SHIFTS REEVALUATE THE POTENTIAL NEED FOR LOW POPS DURING THE EARLY MORNING HOURS ON SUNDAY. CLOUD COVER REALLY KEPT TEMPERATURES ACROSS OUR CWA ON THE COOL SIDE DURING THE DAY FRIDAY. THE STRATUS DECK HAS NOT BEEN NEARLY AS DENSE AS EXPECTED TONIGHT HOWEVER AND THE CURRENT THINKING IS THIS STRATUS SHOULD DISSIPATE AND LIFT BY MID TO LATE MORNING WHICH SHOULD ALLOW FOR WARMER AFTERNOON HIGHS. GUIDANCE FROM THE MET...MAV...AND ECS SEEMS TO HAVE A GOOD HANDLE ON THIS AND TAKING AN EVEN AVERAGE OF THE THREE PROVIDES AFTERNOON HIGH TEMPERATURES IN THE UPPER 70S TO NEAR 80 ACROSS MUCH OF THE CWA. CLEARER SKIES SHOULD ALLOW FOR A SLIGHTLY COOLER OVERNIGHT LOWS TONIGHT WHEN COMPARED TO EARLY THIS MORNING...WITH OVERNIGHT LOWS IN THE UPPER 50S TO NEAR 60 CURRENTLY FORECAST FOR MOST LOCATIONS TONIGHT. FINALLY...NEAR-ZERO LOW LEVEL DEW POINT DEPRESSIONS AND A FAIRLY LIGHT SOUTH/SOUTHEAST LOW LEVEL WIND FIELD COULD PROMOTE PATCHY FOG ACROSS THE AREA TOWARDS SUNRISE SUNDAY. VISIBILITY RESTRICTION IS NOT EXPECTED TO BE SIGNIFICANT...BUT WILL GO AHEAD WITH PATCHY FOG IN THE GRIDS BEGINNING 09Z SUNDAY. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 346 AM CDT SAT AUG 17 2013 A RELATIVELY QUIET WEATHER PATTERN WILL BECOME EVIDENT BEGINNING SUNDAY AS HIGH PRESSURE CONTINUES TO SLIDE OVER THE REGION FROM THE INTERMOUNTAIN WEST. WATER VAPOR IMAGERY DEPICTS A 500MB TROUGH OVER THE EASTERN PART OF THE CONUS...WHILE HIGH PRESSURE IS BUILDING IN OVER MOST OF THE WESTERN CONUS. THERE IS A SHORT WAVE TROUGH EVIDENT OVER THE PACIFIC NORTHWEST AS WELL. MODELS ARE IN GOOD AGREEMENT WITH REGARDS TO HIGH PRESSURE BUILDING IN FROM THE WEST TO CONTINUE. THIS PATTERN WILL MAKE FOR WARMER DAYS AHEAD WITH TEMPERATURES FORECAST TO BE MORE SEASONABLE THAN THE PREVIOUS WEEK. THE PATTERN OVER THE NEXT WEEK IS SHOWING UNFAVORABLE CONDITIONS FOR ANY PRECIPITATION AND HENCE A DRY FORECAST THROUGH MOST OF THE EXTENDED AS HIGH PRESSURE DOMINATES THE REGION. THURSDAY NIGHT INTO FRIDAY APPEARS TO BE THE ONLY DAY SHOWING ANY CHANCE FOR PRECIPITATION...BUT THE LATEST RUNS OF THE GFS AND EC ARE BOTH BEGINNING TO SHOW DRY CONDITIONS IN THE EXTENDED. SINCE THIS IS THE FIRST RUN OF THE EC AND GFS AGREEING IN FAVOR OF DRIER CONDITIONS...I WILL LEAVE THE SLIGHT CHANCES IN THERE FOR THURSDAY NIGHT INTO FRIDAY UNTIL SOME CONSISTENCY EVOLVES. DONT WANT A FLIP FLOP SCENARIO DEVELOPING. I CAN SEE THESE POPS GETTING YANKED IF THIS TREND CONTINUES INTO DAY SHIFT THOUGH. SEEMS VERY REASONABLE TO HAVE THE DRY FORECAST BASED ON THE HIGH PRESSURE STILL PROGGED TO BE NEARLY CENTERED OVER THE CENTRAL PLAINS REGION COME FRIDAY. WITH THE HELP OF HIGH PRESSURE BUILDING IN OVER THE REGION...TEMPERATURES WILL BE MORE SEASONABLE THROUGH THE EXTENDED. SUNDAY WILL BE THE COOLEST DAY OVER THE FORECAST PERIOD...WITH HIGHS RANGING FROM THE LOWER 80S TO UPPER 80S. MONDAY WILL BE SLIGHTLY WARMER. BUT BY TUESDAY...HIGH TEMPERATURES NEAR 90 DEGREES WILL BE THE NORM THROUGH AT LEAST FRIDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 555 AM CDT SAT AUG 17 2013 VFR CONDITIONS FORECAST THROUGH THE NEXT 24 HOURS. STRATUS...WHICH WAS EXPECTED TO PERSIST OVER PORTIONS OF SOUTH CENTRAL NEBRASKA...HAS MATERIALIZED MORE OVER WESTERN NEBRASKA. LATEST GUIDANCE SUGGESTS THIS STRATUS WILL REMAIN TO THE WEST OF GRI BEFORE DISSIPATING LATER THIS MORNING. GIVEN THE LATEST OBSERVATIONS FROM ACROSS THE REGION...AS WELL AS MODEL GUIDANCE...OPTED TO GO WITH VFR CONDITIONS THROUGH THE TAF PERIOD. THIS WILL NEED TO BE CLOSELY MONITORED THROUGH THE NEXT 3-6 HOURS TO ENSURE THE STRATUS OUT WEST DOES NOT PUSH EAST CLOSER TO GRI...BUT OTHERWISE VFR CONDITIONS SHOULD PERSIST AT GRI. THE SURFACE WIND WILL REMAIN FROM THE SOUTHEAST DURING THE TAF PERIOD...GENERALLY IN THE 6-10KT RANGE. PATCHY FOG WILL BE POSSIBLE TOWARDS SUNRISE SUNDAY...BUT AT THIS TIME SIGNIFICANT VISIBILITY RESTRICTION IS NOT EXPECTED AT KGRI...THUS THE P6SM VISIBILITY FORECAST THROUGHOUT THE TAF. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE...BRYANT SHORT TERM...BRYANT LONG TERM...GUERRERO AVIATION...BRYANT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
230 PM EDT SAT AUG 17 2013 .SYNOPSIS... SURFACE HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL EXTEND SOUTHWARD INTO THE PIEDMONT OF CAROLINAS THROUGH SUNDAY. MEANWHILE WEAK WAVES OF LOW PRESSURE WILL DEVELOP AND MOVE ALONG A STALLED FRONT ACROSS GEORGIA AND COASTAL CAROLINA. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1055 AM SATURDAY... ...CHILLY AND UNSETTLED WEATHER TODAY... SCATTERED TO NUMEROUS PATCHES OF LIGHT RAIN AND DRIZZLE ARE NOTED ON THE KRAX WSR-88D THIS MORNING. THE PRECIPITATION IS LARGELY BEING DRIVEN BY MODEST LOW LEVEL ISENTROPIC LIFT WITH A FAIRLY STRONG SOUTHWESTERLY FLOW ALOFT. THE ISENTROPIC LIFT CAN BE SEEN IN THE 12 UTC KGSO RAOB AND IN THE HMT-SEPS PROJECT VERTICAL PROFILER NEAR NEW BERN. NWP DATA AND TRENDS IN THE NEW BERN PROFILER SUGGEST THAT THE BEST LOW LEVEL FORCING FOR ASCENT WILL SHIFT INTO THE EASTERN PIEDMONT AND COASTAL PLAIN DURING THE NEXT 6 HOURS AND HAVE ACCORDINGLY INCREASED AND FOCUSED NEAR TERM POPS THERE. AFTER THIS PERIOD THERE WILL LIKELY BE A DECREASE IN PRECIP COVERAGE ACROSS THE SOUTHEASTERN AND EASTERN PORTIONS OF THE RAH CWA AS HIGH RES NWP GUIDANCE...PRIMARILY RECENT RUNS OF THE HRRR AND THE 00UTC NSSL WRF-ARW INDICATE. ANOTHER BATCH OF PRECIPITATION IS LIKELY TO PUSH INTO THE SOUTHWESTERN AND WESTERN PIEDMONT LATE THIS AFTERNOON AND EVENING AS ANOTHER PERTURBATION IN THE SOUTHWEST FLOW ALOFT APPROACHES AND ENHANCES THE LOW LOW/MID-LEVEL ASCENT. WHILE RAINFALL AMOUNTS HAVE BEEN SOMEWHAT LIGHT...THEY APPEAR SUFFICIENT TO SUSTAIN AND LOCK IN THE COLD AIR DAMMING AIR MASS ACROSS THE PIEDMONT. BASED ON RECENT OBSERVATIONS HAVE ADJUSTED TEMPS UP A DEGREE OR SO INTO THE 66 TO 76 DEGREE RANGE WHICH IS MORE THAN 10 DEGREES BELOW NORMAL. HAVE REDUCED QPF AMOUNTS A BIT TODAY GIVEN THE ISENTROPIC LIFT APPEARS WEAKER THAN PROGGED 12 TO 36 HOURS AGO AND RADAR AMOUNTS HAVE IN GENERAL BEEN LESS THAN EXPECT. STILL RAIN TOTALS FOR THIS EVENT BEGINNING AT MIDNIGHT WILL LIKELY RANGE BETWEEN A QUARTER AND A HALF INCH. -BLAES TONIGHT...BULK OF RAIN EARLY IN THE EVENING SHOULD OCCUR ACROSS THE NORTHERN AND WESTERN PIEDMONT AS 850MB WARM FRONT GRADUALLY PIVOTS NORTHWEST THROUGH THIS REGION. THE WARMER AIR ALOFT OVER THE RELATIVELY COOL SFC AIR MASS SHOULD RESULT IN AREAS OF FOG ACROSS THE PIEDMONT OVERNIGHT ALONG WITH PATCHES OF LIGHT RAIN. RAIN COVERAGE SHOULD BE LESS OVER THE COASTAL PLAIN AND SANDHILLS. MIN TEMPS IN THE MID 60S NW TO NEAR 70 SE. -WSS && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 310 AM SATURDAY... SUNDAY AND SUNDAY NIGHT...MAIN SHEAR AXIS ALOFT MIGRATES WESTWARD TO A POSITION OVER THE FOOTHILLS INTO THE WESTERN PIEDMONT. AIR MASS PLENTY MOIST ENOUGH TO SUPPORT THE DEVELOPMENT OF SCATTERED-NUMEROUS SHOWERS. FARTHER EAST...MODEL GUIDANCE HINTING AT SOME MID-UPPER LEVEL DRYING TAKING PLACE. IF THIS WERE TO OCCUR...BREAKS IN OVERCAST MAY DESTABILIZE THE LOW LEVEL AIR MASS ENOUGH TO GENERATE SCATTERED SHOWERS AND A FEW THUNDERSTORMS. MODEL GUIDANCE CURRENTLY SUGGEST INSTABILITY AS MARGINAL AT BEST THOUGH BULK SHEAR VALUES SUFFICIENT (30-40KTS) FOR THE DEVELOPMENT OF ORGANIZED CONVECTION. MODEL SFC DATA ALSO DEPICT A WEAK SURFACE BOUNDARY IN VICINITY OF THE COASTAL PLAIN SUNDAY AFTERNOON-EVENING. ANY STORMS THAT FORM AND MOVE ALONG THIS FEATURE MAY EXHIBIT SOME ROTATION. LACK OF SUFFICIENT WIND SPEED SHOULD LIMIT SEVERE POTENTIAL. TEMPS SUNDAY HIGHLY DEPENDENT ON ANY BREAKS IN THE OVERCAST AND EXTENT OF SHOWER ACTIVITY. MOS GUIDANCE HINTING AT SOME RECOVERY OF THE AIR MASS ESPECIALLY IN THE COASTAL PLAIN. FAVOR WAITING TO SEE THE EXTENT OF RAIN COVERAGE TODAY AND DEVELOPMENT OF CAD BEFORE RAISING TEMPS TOO MUCH ON SUNDAY. PLAN TO MAINTAIN MAX TEMPS FROM PREVIOUS FORECAST WITH LOWER 70S NW TO THE LOWER 80S SE. SHOWER CHANCES DWINDLE SUNDAY NIGHT AS SHEAR AXIS WEAKENS IN RESPONSE TO RISING HEIGHTS FROM THE BUILDING SUBTROPICAL RIDGE TO OUR EAST AND AIR MASS NOT AS SATURATED. PLAN TO MAINTAIN A CHANCE TO SLIGHT CHANCE POPS ACROSS THE REGION (HIGHEST IN THE WEST-NW). MIN TEMPS MID-UPPER 60S. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 310 AM SATURDAY... MONDAY THROUGH TUESDAY NIGHT: THE CLOSED LOW CURRENTLY OVER THE LOWER MS RIVER VALLEY IS FORECAST TO OPEN AND LIFT TOWARDS OUR REGION THIS WEEKEND AND SLOWLY MOVE ACROSS OUR AREA MONDAY INTO TUESDAY. THIS FEATURE ALONG WITH ABUNDANT MOISTURE (PW`S OF AROUND 2") IN ADVANCE OF THE SYSTEM SHOULD SET THE STAGE FOR AT LEAST SCATTERED AFTERNOON AND EVENING SHOWERS AND STORMS ACROSS CENTRAL NC ON MONDAY AREAWIDE. TUESDAY THE HIGHEST CONCENTRATION OF SHOWERS AND STORMS IS EXPECTED ACROSS THE SOUTHERN/SOUTHEASTERN HALF OF CENTRAL NC AS THE SHEAR SLOWLY MOVES ACROSS THE AREA. THUS... WE KEEP CHANCE AFTERNOON AND EVENING POPS FOR ALL LOCATIONS MONDAY. TUESDAY WILL DO THE SAME... BUT WILL ADVERTISE LOW CHANCE POPS ACROSS THE NORTH/NORTHWEST AS THE SHEAR AXIS SLOWLY SHIFTS SOUTH/SOUTHEASTWARD ACROSS THE AREA ON TUESDAY... USHERING DRY AIR ALOFT. TEMPERATURES DURING THIS TIME FRAME WILL REBOUND AS ANY LINGERING SURFACE BOUNDARIES ACROSS THE REGION BEGIN TO WASHOUT. HOWEVER... WE MAY SEE THE FAR NORTHWEST PIEDMONT HANG ONTO A RESIDUAL CAD AIRMASS FOR MOST OF THE DAY MONDAY. THUS... WILL SHOW TEMPS RANGING FROM THE UPPER 70S TO NEAR 80 FAR NW TO UPPER 80S SE. TUESDAY EXPECTED WE WILL SEE MID TO UPPER 80S ACROSS THE AREA. LOW TEMPS DURING THIS TIMEFRAME WILL BE NEAR NORMAL... IN THE UPPER 60S TO LOWER 70S. WEDNESDAY THROUGH FRIDAY: THE LINGERING SHEAR AXIS IS EXPECTED TO EITHER REMAIN ACROSS OUR SOUTHERN COUNTIES OR PUSH JUST TO THE SOUTH OF OUR REGION WHILE WEAKENING ON WEDNESDAY INTO THURSDAY. THROUGH 84 HOURS BOTH THE NAM AND GFS SHOW THIS AFOREMENTIONED SHEAR AXIS ACROSS OUR REGION IN A ENE TO WSW FASHION... WHILE THE ECMWF IS SLOWER AND HAS THE FEATURE BACK ACROSS THE HIGHER TERRAIN AT THIS TIME... BEFORE SETTLING THIS FEATURE SOUTH/SOUTHEASTWARD INTO OUR AREA ON TUESDAY AFTERNOON INTO TUESDAY NIGHT THEN LINGERING THE FEATURE ACROSS SOUTHERN PORTIONS OF THE AREA ON WEDNESDAY. THUS... EXPECT THE BEST CHANCE OF SEEING ANY SHOWERS AND STORMS ON WEDNESDAY WILL BE ACROSS SOUTHERN PORTIONS OF THE AREA. THE FORECAST BECOMES MORE UNCLEAR ON THURSDAY INTO FRIDAY... FIRST WITH THE TRACK AN EVOLUTION OF TWO SEPARATE S/W FEATURES. THE GFS ATTEMPTS TO BRING SOME FORM OF S/W ENERGY (POSSIBLY FROM THE REMNANTS OF THE SYSTEM CURRENTLY LOCATION IN THE GULF OF MEXICO) AROUND THE EXPANDING SUB-TROPICAL RIDGE ACROSS THE DEEP SOUTH AND INTO OUR AREA ON THURSDAY INTO THURSDAY NIGHT... WHILE THE LATEST ECMWF (12Z/16TH) HAS A WEAK S/W DROPPING SOUTHWARD OUT OF THE GREAT LAKES ON WEDNESDAY AND MOVING ACROSS THE MID-ATLANTIC REGION LATE THURSDAY INTO FRIDAY. GIVEN THIS AND WPC IS ADVERTISING A BETTER CHANCE OF SHOWERS AND STORMS THAT DAY ACROSS OUR AREA WILL HOLD ONTO CHANCE POPS FOR THURSDAY. ON FRIDAY... THE GFS AND ECMWF DIFFER WITH REGARD TO THE NEXT APPROACHING COLD FRONT... WITH THE GFS BRINGING A FRONT INTO THE AREA BY LATE FRIDAY... WITH THE ECMWF MUCH SLOWER. FOR NOW WILL KEEP POPS AS IS FOR FRIDAY LOW END CHANCE/SLIGHT CHANCE ACROSS THE AREA. TEMPS DURING THIS TIME SHOULD BE NEAR NORMAL... UPPER 80S TO NEAR 90 FOR HIGHS WITH LOWS IN THE UPPER 60S TO LOWER 70S. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 230 PM SATURDAY... HIGH CONFIDENCE OF ADVERSE AVIATION CONDITIONS THROUGH MOST OF THE 24 HOUR TAF PERIOD. MULTIPLE AREAS OF RAIN AND AN ASSOCIATED COOL AND MOIST AIR MASS WILL RESULT IN LOW CEILINGS AND REDUCED VISIBILITIES DURING THE NEXT 24 HOURS. IFR TO LIFR CONDITIONS AT THE TAF LOCATIONS THIS AFTERNOON AREA ASSOCIATED WITH AREAS OF LIGHT TO BRIEFLY HEAVIER RAIN THAT WILL PERSIST INTO THE EVENING. THE LARGE AREA OF SHOWERS ACROSS THE COASTAL PLAIN AND SANDHILLS WILL GRADUALLY MOVE AWAY FROM THE AREA THIS EVENING WITH ANOTHER BATCH OF SHOWERS MOVING INTO THE WESTERN PIEDMONT FROM THE SOUTHWEST THIS EVENING AND PERSISTING INTO THE OVERNIGHT HOURS. OUTSIDE OF THE LARGE AREAS OF RAIN...MORE SCATTERED SHOWERS OR PATCHY DRIZZLE WITH AREAS OF FOG CAN BE EXPECTED. SUNDAY WILL START OFF WITH LOW CEILINGS IN THE LIFR/IFR RANGE. BUT SOME IMPROVEMENT IS POSSIBLE...ESPECIALLY ACROSS THE COASTAL PLAIN NEAR KFAY AND KRWI WHERE BASES MAY LIFT TO THE HIGH END MVFR/LOW END VFR RANGE DURING THE MID TO LATE AFTERNOON. FARTHER WEST IN THE WESTERN PIEDMONT...LOW CEILINGS AND AREAS OF FOG/MIST WILL PERSIST THROUGH MUCH OF THE DAY WITH IFR CONDITIONS DURING THE MORNING SLOWLY IMPROVING TO MVFR BY AFTERNOON. LOOKING FURTHER AHEAD...LINGERING LOW CLOUDS AND SHOWERS ARE EXPECTED LATE SUNDAY THROUGH MONDAY...ESPECIALLY ACROSS THE INTERIOR PIEDMONT. CONDITIONS ARE EXPECTED TO GENERALLY IMPROVE DURING THE MID TO LATE WEEK PERIOD. MAINLY SCATTERED AFTERNOON OR EVENING CONVECTION IS POSSIBLE...ESPECIALLY ACROSS THE SOUTHERN PORTIONS OF THE FORECAST AREA. -BLAES && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...BLAES/WSS SHORT TERM...WSS LONG TERM...BSD AVIATION...BLAES
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1055 AM EDT SAT AUG 17 2013 .SYNOPSIS... SURFACE HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC WILL EXTEND SOUTHWARD INTO THE PIEDMONT OF CAROLINAS THROUGH SUNDAY. MEANWHILE WEAK WAVES OF LOW PRESSURE WILL DEVELOP AND MOVE ALONG A STALLED FRONT ACROSS GEORGIA AND COASTAL CAROLINA. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1055 AM SATURDAY... ...CHILLY AND UNSETTLED WEATHER TODAY... SCATTERED TO NUMEROUS PATCHES OF LIGHT RAIN AND DRIZZLE ARE NOTED ON THE KRAX WSR-88D THIS MORNING. THE PRECIPITATION IS LARGELY BEING DRIVEN BY MODEST LOW LEVEL ISENTROPIC LIFT WITH A FAIRLY STRONG SOUTHWESTERLY FLOW ALOFT. THE ISENTROPIC LIFT CAN BE SEEN IN THE 12 UTC KGSO RAOB AND IN THE HMT-SEPS PROJECT VERTICAL PROFILER NEAR NEW BERN. NWP DATA AND TRENDS IN THE NEW BERN PROFILER SUGGEST THAT THE BEST LOW LEVEL FORCING FOR ASCENT WILL SHIFT INTO THE EASTERN PIEDMONT AND COASTAL PLAIN DURING THE NEXT 6 HOURS AND HAVE ACCORDINGLY INCREASED AND FOCUSED NEAR TERM POPS THERE. AFTER THIS PERIOD THERE WILL LIKELY BE A DECREASE IN PRECIP COVERAGE ACROSS THE SOUTHEASTERN AND EASTERN PORTIONS OF THE RAH CWA AS HIGH RES NWP GUIDANCE...PRIMARILY RECENT RUNS OF THE HRRR AND THE 00UTC NSSL WRF-ARW INDICATE. ANOTHER BATCH OF PRECIPITATION IS LIKELY TO PUSH INTO THE SOUTHWESTERN AND WESTERN PIEDMONT LATE THIS AFTERNOON AND EVENING AS ANOTHER PERTURBATION IN THE SOUTHWEST FLOW ALOFT APPROACHES AND ENHANCES THE LOW LOW/MID-LEVEL ASCENT. WHILE RAINFALL AMOUNTS HAVE BEEN SOMEWHAT LIGHT...THEY APPEAR SUFFICIENT TO SUSTAIN AND LOCK IN THE COLD AIR DAMMING AIR MASS ACROSS THE PIEDMONT. BASED ON RECENT OBSERVATIONS HAVE ADJUSTED TEMPS UP A DEGREE OR SO INTO THE 66 TO 76 DEGREE RANGE WHICH IS MORE THAN 10 DEGREES BELOW NORMAL. HAVE REDUCED QPF AMOUNTS A BIT TODAY GIVEN THE ISENTROPIC LIFT APPEARS WEAKER THAN PROGGED 12 TO 36 HOURS AGO AND RADAR AMOUNTS HAVE IN GENERAL BEEN LESS THAN EXPECT. STILL RAIN TOTALS FOR THIS EVENT BEGINNING AT MIDNIGHT WILL LIKELY RANGE BETWEEN A QUARTER AND A HALF INCH. -BLAES TONIGHT...BULK OF RAIN EARLY IN THE EVENING SHOULD OCCUR ACROSS THE NORTHERN AND WESTERN PIEDMONT AS 850MB WARM FRONT GRADUALLY PIVOTS NORTHWEST THROUGH THIS REGION. THE WARMER AIR ALOFT OVER THE RELATIVELY COOL SFC AIR MASS SHOULD RESULT IN AREAS OF FOG ACROSS THE PIEDMONT OVERNIGHT ALONG WITH PATCHES OF LIGHT RAIN. RAIN COVERAGE SHOULD BE LESS OVER THE COASTAL PLAIN AND SANDHILLS. MIN TEMPS IN THE MID 60S NW TO NEAR 70 SE. -WSS && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... AS OF 310 AM SATURDAY... SUNDAY AND SUNDAY NIGHT...MAIN SHEAR AXIS ALOFT MIGRATES WESTWARD TO A POSITION OVER THE FOOTHILLS INTO THE WESTERN PIEDMONT. AIR MASS PLENTY MOIST ENOUGH TO SUPPORT THE DEVELOPMENT OF SCATTERED-NUMEROUS SHOWERS. FARTHER EAST...MODEL GUIDANCE HINTING AT SOME MID-UPPER LEVEL DRYING TAKING PLACE. IF THIS WERE TO OCCUR...BREAKS IN OVERCAST MAY DESTABILIZE THE LOW LEVEL AIR MASS ENOUGH TO GENERATE SCATTERED SHOWERS AND A FEW THUNDERSTORMS. MODEL GUIDANCE CURRENTLY SUGGEST INSTABILITY AS MARGINAL AT BEST THOUGH BULK SHEAR VALUES SUFFICIENT (30-40KTS) FOR THE DEVELOPMENT OF ORGANIZED CONVECTION. MODEL SFC DATA ALSO DEPICT A WEAK SURFACE BOUNDARY IN VICINITY OF THE COASTAL PLAIN SUNDAY AFTERNOON-EVENING. ANY STORMS THAT FORM AND MOVE ALONG THIS FEATURE MAY EXHIBIT SOME ROTATION. LACK OF SUFFICIENT WIND SPEED SHOULD LIMIT SEVERE POTENTIAL. TEMPS SUNDAY HIGHLY DEPENDENT ON ANY BREAKS IN THE OVERCAST AND EXTENT OF SHOWER ACTIVITY. MOS GUIDANCE HINTING AT SOME RECOVERY OF THE AIR MASS ESPECIALLY IN THE COASTAL PLAIN. FAVOR WAITING TO SEE THE EXTENT OF RAIN COVERAGE TODAY AND DEVELOPMENT OF CAD BEFORE RAISING TEMPS TOO MUCH ON SUNDAY. PLAN TO MAINTAIN MAX TEMPS FROM PREVIOUS FORECAST WITH LOWER 70S NW TO THE LOWER 80S SE. SHOWER CHANCES DWINDLE SUNDAY NIGHT AS SHEAR AXIS WEAKENS IN RESPONSE TO RISING HEIGHTS FROM THE BUILDING SUBTROPICAL RIDGE TO OUR EAST AND AIR MASS NOT AS SATURATED. PLAN TO MAINTAIN A CHANCE TO SLIGHT CHANCE POPS ACROSS THE REGION (HIGHEST IN THE WEST-NW). MIN TEMPS MID-UPPER 60S. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 310 AM SATURDAY... MONDAY THROUGH TUESDAY NIGHT: THE CLOSED LOW CURRENTLY OVER THE LOWER MS RIVER VALLEY IS FORECAST TO OPEN AND LIFT TOWARDS OUR REGION THIS WEEKEND AND SLOWLY MOVE ACROSS OUR AREA MONDAY INTO TUESDAY. THIS FEATURE ALONG WITH ABUNDANT MOISTURE (PW`S OF AROUND 2") IN ADVANCE OF THE SYSTEM SHOULD SET THE STAGE FOR AT LEAST SCATTERED AFTERNOON AND EVENING SHOWERS AND STORMS ACROSS CENTRAL NC ON MONDAY AREAWIDE. TUESDAY THE HIGHEST CONCENTRATION OF SHOWERS AND STORMS IS EXPECTED ACROSS THE SOUTHERN/SOUTHEASTERN HALF OF CENTRAL NC AS THE SHEAR SLOWLY MOVES ACROSS THE AREA. THUS... WE KEEP CHANCE AFTERNOON AND EVENING POPS FOR ALL LOCATIONS MONDAY. TUESDAY WILL DO THE SAME... BUT WILL ADVERTISE LOW CHANCE POPS ACROSS THE NORTH/NORTHWEST AS THE SHEAR AXIS SLOWLY SHIFTS SOUTH/SOUTHEASTWARD ACROSS THE AREA ON TUESDAY... USHERING DRY AIR ALOFT. TEMPERATURES DURING THIS TIME FRAME WILL REBOUND AS ANY LINGERING SURFACE BOUNDARIES ACROSS THE REGION BEGIN TO WASHOUT. HOWEVER... WE MAY SEE THE FAR NORTHWEST PIEDMONT HANG ONTO A RESIDUAL CAD AIRMASS FOR MOST OF THE DAY MONDAY. THUS... WILL SHOW TEMPS RANGING FROM THE UPPER 70S TO NEAR 80 FAR NW TO UPPER 80S SE. TUESDAY EXPECTED WE WILL SEE MID TO UPPER 80S ACROSS THE AREA. LOW TEMPS DURING THIS TIMEFRAME WILL BE NEAR NORMAL... IN THE UPPER 60S TO LOWER 70S. WEDNESDAY THROUGH FRIDAY: THE LINGERING SHEAR AXIS IS EXPECTED TO EITHER REMAIN ACROSS OUR SOUTHERN COUNTIES OR PUSH JUST TO THE SOUTH OF OUR REGION WHILE WEAKENING ON WEDNESDAY INTO THURSDAY. THROUGH 84 HOURS BOTH THE NAM AND GFS SHOW THIS AFOREMENTIONED SHEAR AXIS ACROSS OUR REGION IN A ENE TO WSW FASHION... WHILE THE ECMWF IS SLOWER AND HAS THE FEATURE BACK ACROSS THE HIGHER TERRAIN AT THIS TIME... BEFORE SETTLING THIS FEATURE SOUTH/SOUTHEASTWARD INTO OUR AREA ON TUESDAY AFTERNOON INTO TUESDAY NIGHT THEN LINGERING THE FEATURE ACROSS SOUTHERN PORTIONS OF THE AREA ON WEDNESDAY. THUS... EXPECT THE BEST CHANCE OF SEEING ANY SHOWERS AND STORMS ON WEDNESDAY WILL BE ACROSS SOUTHERN PORTIONS OF THE AREA. THE FORECAST BECOMES MORE UNCLEAR ON THURSDAY INTO FRIDAY... FIRST WITH THE TRACK AN EVOLUTION OF TWO SEPARATE S/W FEATURES. THE GFS ATTEMPTS TO BRING SOME FORM OF S/W ENERGY (POSSIBLY FROM THE REMNANTS OF THE SYSTEM CURRENTLY LOCATION IN THE GULF OF MEXICO) AROUND THE EXPANDING SUB-TROPICAL RIDGE ACROSS THE DEEP SOUTH AND INTO OUR AREA ON THURSDAY INTO THURSDAY NIGHT... WHILE THE LATEST ECMWF (12Z/16TH) HAS A WEAK S/W DROPPING SOUTHWARD OUT OF THE GREAT LAKES ON WEDNESDAY AND MOVING ACROSS THE MID-ATLANTIC REGION LATE THURSDAY INTO FRIDAY. GIVEN THIS AND WPC IS ADVERTISING A BETTER CHANCE OF SHOWERS AND STORMS THAT DAY ACROSS OUR AREA WILL HOLD ONTO CHANCE POPS FOR THURSDAY. ON FRIDAY... THE GFS AND ECMWF DIFFER WITH REGARD TO THE NEXT APPROACHING COLD FRONT... WITH THE GFS BRINGING A FRONT INTO THE AREA BY LATE FRIDAY... WITH THE ECMWF MUCH SLOWER. FOR NOW WILL KEEP POPS AS IS FOR FRIDAY LOW END CHANCE/SLIGHT CHANCE ACROSS THE AREA. TEMPS DURING THIS TIME SHOULD BE NEAR NORMAL... UPPER 80S TO NEAR 90 FOR HIGHS WITH LOWS IN THE UPPER 60S TO LOWER 70S. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 655 AM SATURDAY... WARM MOIST AIR BEING LIFTED OVER THE COOL DRY STABLE AIR MASS AT THE SURFACE HAS CAUSED LOW CLOUDS AND AREAS OF RAIN TO DEVELOP ACROSS CENTRAL NC SINCE 09Z. WIDESPREAD MVFR CEILINGS EXPECTED BY MID-LATE MORNING ACROSS ALL OF CENTRAL NC WITH POCKETS OF IFR CEILING PROBABLE THIS AFTERNOON. THE LIKELIHOOD OF IFR CEILINGS BY DUSK APPEARS TO BE A GOOD BET WITH PATCHES OF RAIN PERSISTING WELL INTO THE EVENING HOURS BEFORE AREAS OF DRIZZLE AND FOG LIMIT THE VISIBILITY. SUNDAY WILL START OUT WITH LOW CEILINGS IN THE LIFR/IFR RANGE. BY AFTERNOON...COULD SEE SOME IMPROVEMENT...ESPECIALLY IN VICINITY OF KFAY AND KRWI WHERE BASES MAY LIFT TO THE HIGH END MVFR/LOW END VFR BY MID-LATE AFTERNOON. FARTHER WEST...CEILINGS WILL LIKELY BE IN THE MVFR CATEGORY ALL DAY ALONG WITH SPOTTY LIGHT RAIN OR RAIN SHOWERS. AFTERNOON HEATING MAY TRIGGER AN ISOLATED THUNDERSTORM OR TWO IN THE COASTAL PLAIN. MVFR CONDITIONS DUE TO CEILINGS WILL PERSIST SUNDAY NIGHT INTO EARLY MONDAY WITH A PERIOD OF IFR CEILINGS HIGHLY PROBABLY. HEATING SHOULD RAISE CLOUD BASES TO THE HIGH END MVFR IN THE TRIAD WITH LOW END VFR BASES ANTICIPATED ELSEWHERE. ADDITIONAL HEATING OF THE MOIST AIR MASS SHOULD TRIGGER SCATTERED CONVECTION...MAINLY IN THE SANDHILLS AND COASTAL PLAIN MONDAY AFTERNOON...DIMINISHING MONDAY EVENING. AVIATION WEATHER CONDITIONS WILL GRADUALLY IMPROVE TUESDAY AND WEDNESDAY. WHILE PERIODS OF MVFR CEILINGS STILL ANTICIPATED DURING THE OVERNIGHT INTO THE EARLY MORNING HOURS...PERIODS OF VFR CONDITIONS WILL LENGTHEN IN DURATION. SCATTERED AFTERNOON-EARLY EVENING CONVECTION IS ALSO PROBABLE. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...BLAES/WSS SHORT TERM...WSS LONG TERM...BSD AVIATION...WSS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1007 AM EDT SAT AUG 17 2013 .SYNOPSIS... COOL AND WET WEATHER WILL CONTINUE FOR MUCH OF THE WEEKEND AS DEEP TROPICAL MOISTURE STREAMS NORTHWARD ALONG A FRONTAL BOUNDARY. CONDITIONS MORE TYPICAL OF LATE AUGUST WILL DEVELOP NEXT WEEK AS THE FRONT SLOWLY DISSIPATES AND BERMUDA HIGH PRESSURE BECOMES THE MAIN INFLUENCE ON OUR WEATHER. && .NEAR TERM /THROUGH TONIGHT/... AS OF 10 AM SATURDAY...A FRONT REMAINS POSITIONED OFFSHORE. UNSEASONABLY COOL TEMPERATURES ARE EXPECTED AGAIN TODAY AS CLOUDS BLANKET THE FORECAST AREA FOR MOST OF THE DAY. HIGHS ARE ONLY EXPECTED TO REACH THE MID AND UPPER 70S. A LARGE AREA OF SHOWERS AND A FEW THUNDERSTORMS...COINCIDENT WITH A WAVE OF LOW PRESSURE MOVING UP A STALLED OFFSHORE FRONT...WAS PROGRESSING TO THE NORTHEAST LATE THIS MORNING. THE BRUNT OF THIS CONVECTION WILL MOVE ACROSS THE WATERS AND OFFSHORE THROUGH THE AFTERNOON. HOWEVER...THE WESTERN FRINGES OF THIS ACTIVITY WILL SKIRT THE COAST AS THE AREA EXPANDS...ESPECIALLY THE CAPE FEAR AREA. THUS...FOR THE NEXT SEVERAL HOURS...EXPECT THE COVERAGE OF SHOWERS TO INCREASE...ESPECIALLY ALONG AND EAST OF A LINE FROM CRE TO CPC AND EYF. A THUNDERSTORM CAN NOT BE RULED OUT ALTHOUGH MOST OF THE THUNDERSTORM ACTIVITY IS EXPECTED TO REMAIN ON THE WARM SIDE OF THE OFFSHORE FRONT. DEVELOPING SUBSIDENCE DOWNSTREAM OF THIS ACTIVITY IS EXPECTED TO HELP SQUELCH CONVECTION WEST OF THE AFOREMENTIONED LINE FOR THE NEXT SEVERAL HOURS. WILL SHOW POPS EVENTUALLY TRENDING HIGHER IN THESE AREAS DURING THE AFTERNOON. A SERIES OF WAVES MOVING ALONG THE FRONT AND INDUCED BY UPPER LEVEL DISTURBANCES RIDING UP THE LEADING EDGE OF AN UNSEASONABLY DEEP H/5 EAST COAST TROUGH WILL KEEP THE WEATHER UNSETTLED. OVERRUNNING PATTERN IN PLACE FOR THE PAST FEW DAYS STILL VERY EVIDENT...WITH A DEEP TROPICALLY-SOURCED AIRMASS OVERRIDING A RELATIVELY COOL AND MOIST EASTERLY FLOW CLOSER TO THE SURFACE. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 315 AM SATURDAY...THE FA WILL LIE IN BETWEEN THE WESTERN ATLANTIC RIDGE AND THE CUTOFF LOW ACROSS THE CENTRAL MISSISSIPPI VALLEY. AMPLE SUPPLY OF MOISTURE ACROSS THE FA...AS FEEDS FROM BOTH THE ATLANTIC AT THE LOW LEVELS...AND THE GULF OF MEXICO MID AND UPPER LEVELS...ADVECT ACROSS THE FA. WEAK AREA OF LOW PRESSURE IS PROGGED BY THE MODELS TO TRAVEL ALONG A COASTAL TROF/FRONT ORIENTED NE-SW OVER THE ATLANTIC WATERS..AND PARALLEL TO THE CAROLINA COASTS. THE LOW DEPARTS TO THE NE OFF THE DELMARVA COAST BY DAYBREAK MONDAY. UPSTAIRS...THE CUTOFF LOW ACROSS THE CENTRAL PART OF THE U.S. OPENS UP INTO A PROGRESSIVE POSITIVELY TILTED S/W TROF WHICH REACHES THE NE AND MID-ATLANTIC STATES LATE MONDAY NIGHT. AT THE SFC ON SUNDAY...WEAK HIGH PRESSURE IS PROGGED TO AFFECT THE FA. ONE WOULD THINK THAT WE ARE SAFE FROM ANY PCPN OCCURRENCE ON MONDAY. HOWEVER...MOISTURE REMAINS IN ABUNDANCE ACROSS THE FA. WEAK 5H VORTICIES ARE PROGGED TO PUSH ACROSS THE FA MONDAY INTO MONDAY NIGHT. IN ADDITION...ANY AMOUNT OF INSOLATION EITHER DAY WILL RESULT IN FURTHER DESTABILIZATION OF THE ATM LOCALLY. AS A RESULT OF ALL THIS SAID...POPS SUNDAY AND MONDAY WILL BE IN THE MODERATE TO HIGH CHANCE CATEGORY. THIS IS IN GOOD AGREEMENT WITH BOTH THE NAM AND GFS MOS GUIDANCE. FOR MAX TEMPS...LEANED TOWARD THE SLIGHTLY HIGHER NAM MOS GUIDANCE WHEN COMPARED TO THE GFS. AS FOR LOWS...BOTH MODEL MOS GUIDANCE QUITE SIMILAR AND SEE NO REASON TO DETOUR FROM THEIR OUTPUT. THE LATEST HPC 48 HR GUIDANCE FOR RAINFALL ACROSS THE ILM CWA...INDICATES BETWEEN 1 TO 2 INCHES POSSIBLE. AT THIS POINT A FLOOD WATCH IS NOT RECOMMENDED...BUT AS GROUNDS FURTHER BECOME SATURATED...WILL HAVE TO RE-VISIT THIS ISSUE ONCE AGAIN IF HPC FUTURE PCPN FORECASTS COME IN AT MODEST TO HIGH LEVELS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 315 AM SATURDAY...THE OPENED UP UPPER TROF WILL JUST BECOME A MEMORY AS ITS IS ABSORBED WITHIN THE MAIN BELT OF THE UPPER WESTERLIES. WITH NW FLOW ALOFT...THIN BAND OF MOISTURE...HAVING BEEN STRETCHED APART WILL DROP SE-WARD...AND CROSS THE FA DURING WEDNESDAY. BEWARE THE NW FLOW...AN ADAGE THAT HAS COME TO LIGHT WHEN DEALING WITH CONVECTION DROPPING SE-WARD FROM UPSTREAM. A MCC OR MCS USUALLY IS THE CULPRIT WITH THIS TYPE MID/UPPER LEVEL FLOW. CHANCE POPS WILL CONTINUE FOR TUE AND WED. BY THU AND FRI...MODELS DIVERGE FROM ONE ANOTHER WITH THEIR OWN RESPECTIVE SOLUTIONS DEALING WITH THE RE-TURN OF MOISTURE AND INCREASING POPS. REMAINED RATHER SOMEWHAT LOW-KEY WITH POPS THIS LATE IN THE TIME PERIOD DUE TO THE UNCERTAINTY. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 12Z...CEILINGS THIS MORNING WILL BE PREDOMINATELY IFR... HOWEVER THEY WILL PROBABLY BOUNCE IN AND OUT OF MVFR...PARTICULARLY AFTER 15Z. THE HRRR MODEL HAS A SURFACE LOW OFFSHORE THAT WILL MOVE SLOWLY NORTHEAST THROUGH THE DAY. THE MODEL IS NOT ALL THAT ENTHUSED WITH THE PRECIP TODAY...WITH MAINLY ONLY SCATTERED ACTIVITY. BASED ON THE CURRENT RADAR...THIS SCENARIO SEEMS REASONABLE. VISIBILITIES IN THE RAIN COULD LOWER TO IFR...BUT PREDOMINATELY MVFR. WINDS ARE A BIT MORE NORTHERLY THAN PREVIOUSLY THOUGHT...PARTICULARLY INLAND ON THE BACK SIDE OF THE SURFACE LOW. LOOK FOR THE WINDS TO SHIFT MORE NORTHWESTERLY AS THE LOW EXITS THE REGION THIS AFTERNOON. EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 10 AM SATURDAY...A FRONT REMAINS STALLED OFFSHORE LATE THIS MORNING. THIS FRONT IS EXPECTED TO MOVE BACK ACROSS THE WATERS AS WAVES OF LOW PRESSURE MOVE UP ALONG THE BOUNDARY. THUS EASTERLY WINDS ARE EXPECTED TO VEER TO A MORE SOUTHERLY DIRECTION THROUGH THE AFTERNOON AND THEN TO SOUTHWEST FOR A TIME. WINDS WILL VEER TO W OR NW TONIGHT AS A WAVE OF LOW PRESSURE CLOSES OFF AND MOVES TO OUR N. WIND SPEEDS WILL GENERALLY BE AROUND 10 KT OR LESS. SEAS OF 2 TO 3 FT WILL PERSIST. NUMEROUS TO WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS WILL RESULT IN POOR VISIBILITIES INTO TONIGHT. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 330 AM SATURDAY...THE WESTERN ATLANTIC UPPER RIDGE AXIS IS PROGGED TO EXTEND FURTHER WESTWARD...PUSHING THE MAIN MOISTURE PLUME ORIENTED NE-SW FURTHER INLAND. THIS WILL POSSIBLY PROVIDE SOME DRYING CONDITIONS FOR MARINERS TRAVERSING THE LOCAL AND OFFSHORE WATERS LATER SUNDAY INTO MONDAY. AN EXITING SFC LOW TO THE NE ALONG A COASTAL FRONT WILL HIGHLIGHT SUNDAY...FOLLOWED BY WEAK HIGH PRESSURE ACROSS THE AREA FOR MONDAY. THE SFC PRESSURE GRADIENT WILL TIGHTEST AT THE BEGINNING OF THE SHORT TERM RELATIVELY SPEAKING...THEN RELAX THROUGH MONDAY AS HIGH PRESSURE BECOMES DOMINATE WX FEATURE. FOR SIGNIFICANT SEAS...AN ESE GROUND SWELL AT 9 SECOND PERIODS TO APPROACH THE LOCAL WATERS SUNDAY...AND AFFECT THE WATERS LATE SUNDAY NIGHT THROUGH MONDAY. EXPECT WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS WILL DOMINATE AT THE START...BUT EVEN OUT ONCE THE SWELL TRAVERSES THE WATERS. 2 TO 3 FT...LIKELY HIGHER ONCE THE SWELL PUSHES ACROSS THE WATERS. LATEST WAVEWATCH3 ILLUSTRATES THIS OCCURRENCE. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED BY SUPPRESSED UPPER RIDGING TO THE SOUTH WITH WEAK HIGH PRESSURE SPORADICALLY COVERING THE SE STATES. OVERALL WINDS WILL BE LIGHT...LESS THAN 10 KT. PREVAILING WIND DIRECTION WILL BE SOMEWHAT DIFFICULT TO FORECAST...COULD ALMOST GO WITH A VARIABLE DIRECTION AT TIMES. SIGNIFICANT SEAS WILL DROP TO AROUND 2 FT BY WED AS THE DECAYING ESE SWELL GIVES WAY TO LOCALLY PRODUCED WIND DRIVEN WAVES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...RJD SHORT TERM...DCH LONG TERM...DCH AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1059 AM EDT SAT AUG 17 2013 .SYNOPSIS... COOL AND WET WEATHER WILL CONTINUE FOR MUCH OF THE WEEKEND AS DEEP TROPICAL MOISTURE STREAMS NORTHWARD ALONG A FRONTAL BOUNDARY. CONDITIONS MORE TYPICAL OF LATE AUGUST WILL DEVELOP NEXT WEEK AS THE FRONT SLOWLY DISSIPATES AND BERMUDA HIGH PRESSURE BECOMES THE MAIN INFLUENCE ON OUR WEATHER. && .NEAR TERM /THROUGH TONIGHT/... AS OF 10 AM SATURDAY...A FRONT REMAINS POSITIONED OFFSHORE. UNSEASONABLY COOL TEMPERATURES ARE EXPECTED AGAIN TODAY AS CLOUDS BLANKET THE FORECAST AREA FOR MOST OF THE DAY. HIGHS ARE ONLY EXPECTED TO REACH THE MID AND UPPER 70S. A LARGE AREA OF SHOWERS AND A FEW THUNDERSTORMS...COINCIDENT WITH A WAVE OF LOW PRESSURE MOVING UP A STALLED OFFSHORE FRONT...WAS PROGRESSING TO THE NORTHEAST LATE THIS MORNING. THE BRUNT OF THIS CONVECTION WILL MOVE ACROSS THE WATERS AND OFFSHORE THROUGH THE AFTERNOON. HOWEVER...THE WESTERN FRINGES OF THIS ACTIVITY WILL SKIRT THE COAST AS THE AREA EXPANDS...ESPECIALLY THE CAPE FEAR AREA. THUS...FOR THE NEXT SEVERAL HOURS...EXPECT THE COVERAGE OF SHOWERS TO INCREASE...ESPECIALLY ALONG AND EAST OF A LINE FROM CRE TO CPC AND EYF. A THUNDERSTORM CAN NOT BE RULED OUT ALTHOUGH MOST OF THE THUNDERSTORM ACTIVITY IS EXPECTED TO REMAIN ON THE WARM SIDE OF THE OFFSHORE FRONT. DEVELOPING SUBSIDENCE DOWNSTREAM OF THIS ACTIVITY IS EXPECTED TO HELP SQUELCH CONVECTION WEST OF THE AFOREMENTIONED LINE FOR THE NEXT SEVERAL HOURS. WILL SHOW POPS EVENTUALLY TRENDING HIGHER IN THESE AREAS DURING THE AFTERNOON. A SERIES OF WAVES MOVING ALONG THE FRONT AND INDUCED BY UPPER LEVEL DISTURBANCES RIDING UP THE LEADING EDGE OF AN UNSEASONABLY DEEP H/5 EAST COAST TROUGH WILL KEEP THE WEATHER UNSETTLED. OVERRUNNING PATTERN IN PLACE FOR THE PAST FEW DAYS STILL VERY EVIDENT...WITH A DEEP TROPICALLY-SOURCED AIRMASS OVERRIDING A RELATIVELY COOL AND MOIST EASTERLY FLOW CLOSER TO THE SURFACE. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 315 AM SATURDAY...THE FA WILL LIE IN BETWEEN THE WESTERN ATLANTIC RIDGE AND THE CUTOFF LOW ACROSS THE CENTRAL MISSISSIPPI VALLEY. AMPLE SUPPLY OF MOISTURE ACROSS THE FA...AS FEEDS FROM BOTH THE ATLANTIC AT THE LOW LEVELS...AND THE GULF OF MEXICO MID AND UPPER LEVELS...ADVECT ACROSS THE FA. WEAK AREA OF LOW PRESSURE IS PROGGED BY THE MODELS TO TRAVEL ALONG A COASTAL TROF/FRONT ORIENTED NE-SW OVER THE ATLANTIC WATERS..AND PARALLEL TO THE CAROLINA COASTS. THE LOW DEPARTS TO THE NE OFF THE DELMARVA COAST BY DAYBREAK MONDAY. UPSTAIRS...THE CUTOFF LOW ACROSS THE CENTRAL PART OF THE U.S. OPENS UP INTO A PROGRESSIVE POSITIVELY TILTED S/W TROF WHICH REACHES THE NE AND MID-ATLANTIC STATES LATE MONDAY NIGHT. AT THE SFC ON SUNDAY...WEAK HIGH PRESSURE IS PROGGED TO AFFECT THE FA. ONE WOULD THINK THAT WE ARE SAFE FROM ANY PCPN OCCURRENCE ON MONDAY. HOWEVER...MOISTURE REMAINS IN ABUNDANCE ACROSS THE FA. WEAK 5H VORTICIES ARE PROGGED TO PUSH ACROSS THE FA MONDAY INTO MONDAY NIGHT. IN ADDITION...ANY AMOUNT OF INSOLATION EITHER DAY WILL RESULT IN FURTHER DESTABILIZATION OF THE ATM LOCALLY. AS A RESULT OF ALL THIS SAID...POPS SUNDAY AND MONDAY WILL BE IN THE MODERATE TO HIGH CHANCE CATEGORY. THIS IS IN GOOD AGREEMENT WITH BOTH THE NAM AND GFS MOS GUIDANCE. FOR MAX TEMPS...LEANED TOWARD THE SLIGHTLY HIGHER NAM MOS GUIDANCE WHEN COMPARED TO THE GFS. AS FOR LOWS...BOTH MODEL MOS GUIDANCE QUITE SIMILAR AND SEE NO REASON TO DETOUR FROM THEIR OUTPUT. THE LATEST HPC 48 HR GUIDANCE FOR RAINFALL ACROSS THE ILM CWA...INDICATES BETWEEN 1 TO 2 INCHES POSSIBLE. AT THIS POINT A FLOOD WATCH IS NOT RECOMMENDED...BUT AS GROUNDS FURTHER BECOME SATURATED...WILL HAVE TO RE-VISIT THIS ISSUE ONCE AGAIN IF HPC FUTURE PCPN FORECASTS COME IN AT MODEST TO HIGH LEVELS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 315 AM SATURDAY...THE OPENED UP UPPER TROF WILL JUST BECOME A MEMORY AS ITS IS ABSORBED WITHIN THE MAIN BELT OF THE UPPER WESTERLIES. WITH NW FLOW ALOFT...THIN BAND OF MOISTURE...HAVING BEEN STRETCHED APART WILL DROP SE-WARD...AND CROSS THE FA DURING WEDNESDAY. BEWARE THE NW FLOW...AN ADAGE THAT HAS COME TO LIGHT WHEN DEALING WITH CONVECTION DROPPING SE-WARD FROM UPSTREAM. A MCC OR MCS USUALLY IS THE CULPRIT WITH THIS TYPE MID/UPPER LEVEL FLOW. CHANCE POPS WILL CONTINUE FOR TUE AND WED. BY THU AND FRI...MODELS DIVERGE FROM ONE ANOTHER WITH THEIR OWN RESPECTIVE SOLUTIONS DEALING WITH THE RE-TURN OF MOISTURE AND INCREASING POPS. REMAINED RATHER SOMEWHAT LOW-KEY WITH POPS THIS LATE IN THE TIME PERIOD DUE TO THE UNCERTAINTY. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 12Z...CEILINGS THIS MORNING WILL BE PREDOMINATELY IFR... HOWEVER THEY WILL PROBABLY BOUNCE IN AND OUT OF MVFR...PARTICULARLY AFTER 15Z. THE HRRR MODEL HAS A SURFACE LOW OFFSHORE THAT WILL MOVE SLOWLY NORTHEAST THROUGH THE DAY. THE MODEL IS NOT ALL THAT ENTHUSED WITH THE PRECIP TODAY...WITH MAINLY ONLY SCATTERED ACTIVITY. BASED ON THE CURRENT RADAR...THIS SCENARIO SEEMS REASONABLE. VISIBILITIES IN THE RAIN COULD LOWER TO IFR...BUT PREDOMINATELY MVFR. WINDS ARE A BIT MORE NORTHERLY THAN PREVIOUSLY THOUGHT...PARTICULARLY INLAND ON THE BACK SIDE OF THE SURFACE LOW. LOOK FOR THE WINDS TO SHIFT MORE NORTHWESTERLY AS THE LOW EXITS THE REGION THIS AFTERNOON. EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 10 AM SATURDAY...A FRONT REMAINS STALLED OFFSHORE LATE THIS MORNING. THIS FRONT IS EXPECTED TO MOVE BACK ACROSS THE WATERS AS WAVES OF LOW PRESSURE MOVE UP ALONG THE BOUNDARY. THUS EASTERLY WINDS ARE EXPECTED TO VEER TO A MORE SOUTHERLY DIRECTION THROUGH THE AFTERNOON AND THEN TO SOUTHWEST FOR A TIME. WINDS WILL VEER TO W OR NW TONIGHT AS A WAVE OF LOW PRESSURE CLOSES OFF AND MOVES TO OUR N. WIND SPEEDS WILL GENERALLY BE AROUND 10 KT OR LESS. SEAS OF 2 TO 3 FT WILL PERSIST. NUMEROUS TO WIDESPREAD SHOWERS AND ISOLATED THUNDERSTORMS WILL RESULT IN POOR VISIBILITIES INTO TONIGHT. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 330 AM SATURDAY...THE WESTERN ATLANTIC UPPER RIDGE AXIS IS PROGGED TO EXTEND FURTHER WESTWARD...PUSHING THE MAIN MOISTURE PLUME ORIENTED NE-SW FURTHER INLAND. THIS WILL POSSIBLY PROVIDE SOME DRYING CONDITIONS FOR MARINERS TRAVERSING THE LOCAL AND OFFSHORE WATERS LATER SUNDAY INTO MONDAY. AN EXITING SFC LOW TO THE NE ALONG A COASTAL FRONT WILL HIGHLIGHT SUNDAY...FOLLOWED BY WEAK HIGH PRESSURE ACROSS THE AREA FOR MONDAY. THE SFC PRESSURE GRADIENT WILL TIGHTEST AT THE BEGINNING OF THE SHORT TERM RELATIVELY SPEAKING...THEN RELAX THROUGH MONDAY AS HIGH PRESSURE BECOMES DOMINATE WX FEATURE. FOR SIGNIFICANT SEAS...AN ESE GROUND SWELL AT 9 SECOND PERIODS TO APPROACH THE LOCAL WATERS SUNDAY...AND AFFECT THE WATERS LATE SUNDAY NIGHT THROUGH MONDAY. EXPECT WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS WILL DOMINATE AT THE START...BUT EVEN OUT ONCE THE SWELL TRAVERSES THE WATERS. 2 TO 3 FT...LIKELY HIGHER ONCE THE SWELL PUSHES ACROSS THE WATERS. LATEST WAVEWATCH3 ILLUSTRATES THIS OCCURRENCE. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED BY SUPPRESSED UPPER RIDGING TO THE SOUTH WITH WEAK HIGH PRESSURE SPORADICALLY COVERING THE SE STATES. OVERALL WINDS WILL BE LIGHT...LESS THAN 10 KT. PREVAILING WIND DIRECTION WILL BE SOMEWHAT DIFFICULT TO FORECAST...COULD ALMOST GO WITH A VARIABLE DIRECTION AT TIMES. SIGNIFICANT SEAS WILL DROP TO AROUND 2 FT BY WED AS THE DECAYING ESE SWELL GIVES WAY TO LOCALLY PRODUCED WIND DRIVEN WAVES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ NEAR TERM...RJD SHORT TERM...DCH LONG TERM...DCH AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
716 AM EDT SAT AUG 17 2013 .SYNOPSIS... A WARM FRONT EXTENDING FROM EASTERN GEORGIA TO JUST OFF THE CAROLINA COAST WILL LIFT NORTH AND THROUGH THE EASTERN CAROLINAS TODAY...AND BE ACCOMPANIED BY HEAVY RAIN AND THUNDERSTORMS. THE FRONT OR TROF OF LOW PRESSURE WILL STALL OVER THE CAROLINAS...THEN GRADUALLY DISSIPATE BY WEDNESDAY AS BERMUDA HIGH PRESSURE OFFSHORE BECOMES THE MAIN INFLUENCE ON OUR WEATHER. BELOW-NORMAL TEMPERATURES THIS WEEKEND SHOULD RETURN TO NORMAL BY TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 6:30 AM SATURDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: UNSEASONABLY COOL TEMPERATURES WITH CLOUDY SKIES AND THE CERTAINTY OF PRECIPITATION WILL BE THE RULE FOR TODAY AS A QUASI-STATIONARY FRONT WAVERS OVER THE COASTAL PLAIN. AT THE SURFACE THIS MORNING THE QUASI-STATIONARY FRONT EXTENDS ALONG THE COAST FROM THE OUTER BANKS TO NEAR SAVANNAH...THEN INLAND ACROSS SOUTHERN GEORGIA. A SERIES OF WAVES MOVING ALONG THE FRONT ARE INDUCED BY UPPER DISTURBANCES RIDING UP THE LEADING EDGE OF AN UNSEASONABLY DEEP H/5 TROUGH NOW DOMINATING EASTERN CONUS. OVERRUNNING PATTERN IN PLACE PAST FEW DAYS STILL VERY EVIDENT...WITH A DEEP TROPICALLY-SOURCED AIRMASS OVERRIDING A RELATIVELY COOL AND MOIST EASTERLY FLOW CLOSER TO THE SURFACE. A WEDGE OF HIGH PRESSURE WILL CONTINUE TO EXTEND SW ALONG THE APPALACHIANS THROUGH THE PERIOD. CONSENSUS OF GUIDANCE HAS A CLOSED LOW FORMING FROM AN OPEN WAVE ALONG THE FRONT TODAY...ULTIMATELY LIFTING THE NORTHERN PORTION OF THE FRONT NORTH AND EFFECTIVELY PUTTING THE COASTAL CAROLINAS IN THE WARM SECTOR OF THE SYSTEM FOR A BRIEF TIME. MODEL SOUNDINGS CONTINUE TO SHOW A VERY MOIST AIRMASS WITH P/W VALUES IN THE 2.25 INCH RANGE. COMBINATION OF A SATURATED COLUMN...FAVORABLE DYNAMICS AND THE FRONTAL BOUNDARY WILL MAKE FOR A VERY RAINY DAY. GIVEN THIS SCENARIO...100 POPS ARE CERTAINLY WARRANTED. HAVE MAINTAINED THE POSSIBILITY THAT THUNDERSTORMS COULD PRODUCE HEAVY RAIN TODAY AND TONIGHT. TEMPERATURES WILL CONTINUE TO RUN WELL BELOW NORMAL...WITH HIGHS RANGING FROM THE LOWER AND MID 70S INLAND TO THE UPPER 70S AT THE COAST...AND LOWS RANGING FROM THE MID 60S TO AROUND 70. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 315 AM...FOR SUNDAY THE FA WILL LIE IN BETWEEN THE WESTERN ATLANTIC RIDGE AND THE CUTOFF LOW ACROSS THE CENTRAL MISSISSIPPI VALLEY. AMPLE SUPPLY OF MOISTURE ACROSS THE FA...AS FEEDS FROM BOTH THE ATLANTIC AT THE LOW LEVELS...AND THE GULF OF MEXICO MID AND UPPER LEVELS...ADVECT ACROSS THE FA. WEAK AREA OF LOW PRESSURE IS PROGGED BY THE MODELS TO TRAVEL ALONG A COASTAL TROF/FRONT ORIENTED NE-SW OVER THE ATLANTIC WATERS..AND PARALLEL TO THE CAROLINA COASTS. THE LOW DEPARTS TO THE NE OFF THE DELMARVA COAST BY DAYBREAK MONDAY. UPSTAIRS...THE CUTOFF LOW ACROSS THE CENTRAL PART OF THE U.S. OPENS UP INTO A PROGRESSIVE POSITIVELY TILTED S/W TROF WHICH REACHES THE NE AND MID-ATLANTIC STATES LATE MONDAY NIGHT. AT THE SFC ON SUNDAY...WEAK HIGH PRESSURE IS PROGGED TO AFFECT THE FA. ONE WOULD THINK THAT WE ARE SAFE FROM ANY PCPN OCCURRENCE ON MONDAY. HOWEVER...MOISTURE REMAINS IN ABUNDANCE ACROSS THE FA. WEAK 5H VORTICIES ARE PROGGED TO PUSH ACROSS THE FA MONDAY INTO MONDAY NIGHT. IN ADDITION...ANY AMOUNT OF INSOLATION EITHER DAY WILL RESULT IN FURTHER DESTABILIZATION OF THE ATM LOCALLY. AS A RESULT OF ALL THIS SAID...POPS SUNDAY AND MONDAY WILL BE IN THE MODERATE TO HIGH CHANCE CATEGORY. THIS IS IN GOOD AGREEMENT WITH BOTH THE NAM AND GFS MOS GUIDANCE. FOR MAX TEMPS...LEANED TOWARD THE SLIGHTLY HIGHER NAM MOS GUIDANCE WHEN COMPARED TO THE GFS. AS FOR LOWS...BOTH MODEL MOS GUIDANCE QUITE SIMILAR AND SEE NO REASON TO DETOUR FROM THEIR OUTPUT. THE LATEST HPC 48 HR GUIDANCE FOR RAINFALL ACROSS THE ILM CWA...INDICATES BETWEEN 1 TO 2 INCHES POSSIBLE. AT THIS POINT A FLOOD WATCH IS NOT RECOMMENDED...BUT AS GROUNDS FURTHER BECOME SATURATED...WILL HAVE TO RE-VISIT THIS ISSUE ONCE AGAIN IF HPC FUTURE PCPN FORECASTS COME IN AT MODEST TO HIGH LEVELS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 315 AM SATURDAY...FOR TUESDAY...THE OPENED UP UPPER TROF WILL JUST BECOME A MEMORY AS ITS IS ABSORBED WITHIN THE MAIN BELT OF THE UPPER WESTERLIES. WITH NW FLOW ALOFT...THIN BAND OF MOISTURE...HAVING BEEN STRETCHED APART WILL DROP SE- WARD...AND CROSS THE FA DURING WEDNESDAY. BEWARE THE NW FLOW...AN ADAGE THAT HAS COME TO LIGHT WHEN DEALING WITH CONVECTION DROPPING SE-WARD FROM UPSTREAM. A MCC OR MCS USUALLY IS THE CULPRIT WITH THIS TYPE MID/UPPER LEVEL FLOW. CHANCE POPS WILL CONTINUE FOR TUE AND WED. BY THU AND FRI...MODELS DIVERGE FROM ONE ANOTHER WITH THEIR OWN RESPECTIVE SOLUTIONS DEALING WITH THE RE-TURN OF MOISTURE AND INCREASING POPS. REMAINED RATHER SOMEWHAT LOW-KEY WITH POPS THIS LATE IN THE TIME PERIOD DUE TO THE UNCERTAINTY. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 12Z...CEILINGS THIS MORNING WILL BE PREDOMINATELY IFR...HOWEVER THEY WILL PROBABLY BOUNCE IN AND OUT OF MVFR...PARTICULARLY AFTER 15Z. THE HRRR MODEL HAS A SURFACE LOW OFFSHORE THAT WILL MOVE SLOWLY NORTHEAST THROUGH THE DAY. THE MODEL IS NOT ALL THAT ENTHUSED WITH THE PRECIP TODAY...WITH MAINLY ONLY SCATTERED ACTIVITY. BASED ON THE CURRENT RADAR...THIS SCENARIO SEEMS REASONABLE. VISIBILITIES IN THE RAIN COULD LOWER TO IFR...BUT PREDOMINATELY MVFR. WINDS ARE A BIT MORE NORTHERLY THAN PREVIOUSLY THOUGHT...PARTICULARLY INLAND ON THE BACK SIDE OF THE SURFACE LOW. LOOK FOR THE WINDS TO SHIFT MORE NORTHWESTERLY AS THE LOW EXITS THE REGION THIS AFTERNOON. EXTENDED OUTLOOK...ISOLATED TO SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... AS OF 6:30 AM SATURDAY...NO CHANGES TO THE FORECAST WITH THE LATEST UPDATE. PREVIOUS DISCUSSION FOLLOWS: THE PRESENCE OF A QUASI-STATIONARY FRONT OVER THE COASTAL PLAN OF THE EASTERN CAROLINAS WILL KEEP WINDS GENERALLY LIGHT THROUGH THE PERIOD. WINDS WILL BE IN THE 10 KT RANGE...WITH SEAS OF 2 TO 3 FT. BIGGEST THREAT OVER THE COASTAL WATERS TODAY WILL BE FROM HEAVY RAIN AND ISOLATED THUNDERSTORMS...ESPECIALLY DURING THE DAYLIGHT HOURS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 330 AM SATURDAY...THE WESTERN ATLANTIC UPPER RIDGE AXIS IS PROGGED TO EXTEND FURTHER WESTWARD...PUSHING THE MAIN MOISTURE PLUME ORIENTED NE-SW FURTHER INLAND. THIS WILL POSSIBLY PROVIDE SOME DRYING CONDITIONS FOR MARINERS TRAVERSING THE LOCAL AND OFFSHORE WATERS LATER SUNDAY INTO MONDAY. AN EXITING SFC LOW TO THE NE ALONG A COASTAL FRONT WILL HIGHLIGHT SUNDAY...FOLLOWED BY WEAK HIGH PRESSURE ACROSS THE AREA FOR MONDAY. THE SFC PRESSURE GRADIENT WILL TIGHTEST AT THE BEGINNING OF THE SHORT TERM RELATIVELY SPEAKING...THEN RELAX THROUGH MONDAY AS HIGH PRESSURE BECOMES DOMINATE WX FEATURE. FOR SIGNIFICANT SEAS...AN ESE GROUND SWELL AT 9 SECOND PERIODS TO APPROACH THE LOCAL WATERS SUNDAY...AND AFFECT THE WATERS LATE SUNDAY NIGHT THROUGH MONDAY. EXPECT WIND DRIVEN WAVES AT 4 TO 6 SECOND PERIODS WILL DOMINATE AT THE START...BUT EVEN OUT ONCE THE SWELL TRAVERSES THE WATERS. 2 TO 3 FT...LIKELY HIGHER ONCE THE SWELL PUSHES ACROSS THE WATERS. LATEST WAVEWATCH3 ILLUSTRATES THIS OCCURRENCE. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 330 AM SATURDAY...THIS PERIOD WILL BE HIGHLIGHTED BY SUPPRESSED UPPER RIDGING TO THE SOUTH WITH WEAK HIGH PRESSURE SPORADICALLY COVERING THE SE STATES. OVERALL WINDS WILL BE LIGHT...LESS THAN 10 KT. PREVAILING WIND DIRECTION WILL BE SOMEWHAT DIFFICULT TO FORECAST...COULD ALMOST GO WITH A VARIABLE DIRECTION AT TIMES. SIGNIFICANT SEAS WILL DROP TO AROUND 2 FT BY WED AS THE DECAYING ESE SWELL GIVES WAY TO LOCALLY PRODUCED WIND DRIVEN WAVES. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...DCH NEAR TERM...REK SHORT TERM...DCH LONG TERM...DCH AVIATION...43 MARINE...DCH/REK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
349 PM CDT SAT AUG 17 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 343 PM CDT SAT AUG 17 2013 THE MAIN FORECAST CHALLENGE FOR THE PERIOD WILL BE THE PRECIP CHANCES LATER THIS EVENING AND AGAIN ON SUNDAY. A WEAK SURFACE BOUNDARY IS BEGINNING TO ENTER WESTERN NORTH DAKOTA THIS AFTERNOON. A STRONG CAP IN PLACE SHOULD INHIBIT AFTERNOON CONVECTION ALONG THE BOUNDARY. HOWEVER...AS THIS BOUNDARY PUSHES INTO CENTRAL NORTH DAKOTA THIS EVENING...THUNDERSTORMS COULD DEVELOP OVER NORTH CENTRAL NORTH DAKOTA PROXIMATE TO THE BEST UPPER LEVEL DYNAMICS AND WEAKEST CAP. THE 12Z ECMWF/NAM AND 17Z HRRR PROG THIS SCENARIO SO DECIDED TO KEEP SLIGHT CHANCE POPS IN THE GRIDS NORTH CENTRAL TONIGHT. SOME STORMS COULD BECOME STRONG SO WILL HIGHLIGHT THIS THREAT IN THE HWO FOR NOW. AS THE BOUNDARY MOVES INTO EASTERN NORTH DAKOTA SUNDAY...IT IS PROGGED TO BECOME STALLED ACROSS CENTRAL NORTH DAKOTA. AN UPPER WAVE IS FORECAST TO MOVE OVER NORTH DAKOTA THROUGH THE DAY SUNDAY. AS IT DOES...THE CHANCES FOR THUNDERSTORMS WILL GRADUALLY OVERSPREAD THE STATE FROM WEST TO EAST. STORMS SHOULD REMAIN BELOW SEVERE CRITERIA THROUGH SUNDAY AFTERNOON...BUT COULD STRENGTHEN TO SEVERE SUNDAY EVENING. SEE LONG TERM DISCUSSION BELOW FOR MORE DETAILS. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 343 PM CDT SAT AUG 17 2013 THE MAIN FORECAST HIGHLIGHT FOR THE EXTENDED PERIOD WILL BE THE POTENTIAL FOR SEVERE THUNDERSTORMS SUNDAY EVENING. THEREAFTER...PROGRESSIVE WEST TO SOUTHWEST FLOW WITH MULTIPLE EMBEDDED UPPER LEVEL IMPULSES IS FORECAST THROUGH THE REMAINDER OF THE PERIOD. 12Z MODEL DETERMINISTIC MODEL GUIDANCE IS IN GOOD AGREEMENT THROUGH MID BEFORE SOLUTIONS DIVERGE LATE WEEK. THE POTENTIAL FOR SEVERE THUNDERSTORMS WILL INCREASE SUNDAY EVENING AS THE COMBINED FORCING FROM THE SURFACE FRONTAL BOUNDARY AND UPPER LEVEL WAVE ERODES THE CAP. THIS FORCING SHOULD BE SUFFICIENT ENOUGH TO BREAK THE CAP BY EARLY SUNDAY EVENING AND ALLOW CONVECTION TO FIRE ALONG THE SURFACE FRONTAL BOUNDARY. THE ANTECEDENT ENVIRONMENT WILL BE FAVORABLE FOR THE DEVELOPMENT OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL AND MOST OF EASTERN NORTH DAKOTA...WITH ML CAPE FORECAST TO BE NEAR 2000 J/KG BY LATE SUNDAY AFTERNOON/EVENING...INCREASING BOUNDARY LAYER MOISTURE (DEWPOINTS INCREASING INTO THE 60S)...AND 0-6 KM BULK SHEAR TO BE IN THE 25 TO 35 M/S RANGE. FURTHERMORE...THE LATEST DAY 2 OUTLOOK FROM SPC HAS PARTS OF CENTRAL AND MOST OF EASTERN NORTH DAKOTA IN THE SLIGHT RISK. HAIL AND DAMAGING WINDS LOOK TO BE THE MAIN THREATS AND AT THIS TIME WILL HIGHLIGHT THE POSSIBILITY OF SEVERE THUNDERSTORMS IN THE HWO AND STATE FORECAST. FOLLOWING THE FRONTAL PASSAGE/SHORTWAVE MONDAY...DAYTIME UPPER LEVEL RIDGING WILL GIVE WAY TO WESTERLY FLOW ALOFT. THIS WILL CONTINUE THROUGH TUESDAY EVENING AHEAD OF THE EXPECTED COLD FRONT WEDNESDAY AND THURSDAY. CANNOT RULE OUT THE POSSIBILITY OF THUNDERSTORMS/SHOWERS ACROSS THE AREA...AS SEVERAL WEAK IMPULSES MOVE OVER THE STATE. PRECIPITATION CHANCES WILL THEN INCREASE AS A COLD FRONT AND AN UPPER LEVEL SHORT WAVE APPROACH NORTHERN NORTH DAKOTA LATE TUESDAY NIGHT/EARLY WEDNESDAY MORNING...AND AS THEY MOVE OVER THE AREA WEDNESDAY. SIMILAR TO PREVIOUS RUNS...THE 12Z ECWMF CONTINUES TO PAINT A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER THE WEST AND CENTRAL. HOWEVER...THE 12Z GFS CONTINUES TO KEEP NORTH DAKOTA DRY AS IT FORECASTS UPPER LEVEL RIDGING TAKING PLACE. WILL KEEP THE ALLBLEND SOLUTION...TO SPLIT THE DIFFERENCE BETWEEN THE ECWMF AND GFS. FOR FRIDAY AND SATURDAY...PRECIPITATION CHANCES WILL CONTINUE AS SOUTHWESTERLY FLOW TAKES HOLD. MEANWHILE...H850 TEMPERATURES WILL INCREASE TO BETWEEN +26 AND +30 C ON TUESDAY. THIS WILL TRANSLATE TO SURFACE TEMPERATURES IN THE 90S...WITH NEAR 100 DEGREE READING FOR FAR SOUTHERN NORTH DAKOTA. COOLER TEMPERATURES ARE FORECAST ONCE THE COLD FRONT PASSES THROUGH THE AREA WEDNESDAY...WHERE TEMPERATURES ARE EXPECTED TO BE MAINLY IN THE 80S DURING THE DAY AND UPPER 50S/LOWER 60S AT NIGHT THROUGH SATURDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 103 PM CDT SAT AUG 17 2013 VFR CONDITIONS WILL PREVAIL ACROSS NORTH DAKOTA THROUGH THE TAF PERIOD. THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS NEAR KMOT THIS EVENING. CONFIDENCE IS LOW REGARDING AVIATION IMPACTS. THEREFORE...ONLY INCLUDED VCTS IN THE KMOT TAF BETWEEN 00Z-05Z. FURTHERMORE...IFR CIGS/VSBYS COULD DEVELOP NEAR KJMS BETWEEN 11Z- 13Z. CONFIDENCE IS LOW IN THIS MATERIALIZING AND WILL THEREFORE LEAVE OUT OF THE KJMS TAF FOR NOW. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...TM LONG TERM...LTH AVIATION...AC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
103 PM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 103 PM CDT SAT AUG 17 2013 STRATUS DECK OVER THE JAMES RIVER BASIN IS BEGINNING TO ERODE AWAY WITH THE ONSET OF DAYTIME HEATING. THE LOW CLOUDS SHOULD DISSIPATE BY 2 PM CDT. OTHERWISE...ONLY MODIFIED THE HOURLY SENSIBLE WEATHER GRIDS BASED ON CURRENT OBS/TRENDS. THE UPDATED PRODUCTS HAVE BEEN SENT. UPDATE ISSUED AT 1041 AM CDT SAT AUG 17 2013 LOW CLOUDS AND PATCHY FOG ARE LINGERING OVER SOUTH CENTRAL AND SOUTHEASTERN NORTH DAKOTA LONGER THAN ANTICIPATED. AS A RESULT...UPDATED THE FORECAST TO CONTINUE THE CLOUDY AND PATCHY FOG CONDITIONS PRIMARILY ACROSS THE JAMES RIVER BASIN THROUGH THE MID-DAY HOURS. THIS SHOULD ALSO HAMPER MORNING TEMPERATURE WARMING TRENDS. HOWEVER...ONCE THE LOW CLOUDS AND FOG BURN OFF...TEMPERATURES SHOULD RAPIDLY INCREASE THIS AFTERNOON. UPDATE ISSUED AT 830 AM CDT SAT AUG 17 2013 SENT OUT A QUICK UPDATE TO INCREASE FOG COVERAGE OVER THE JAMES RIVER BASIN THROUGH THE MID-MORNING HOURS. EVEN THOUGH SURFACE WINDS ARE AROUND 10 KNOTS...AREAS OF FOG...DENSE AT TIMES...CONTINUE TO DEVELOP OVER PORTIONS OF SOUTHCENTRAL AND SOUTHEASTERN NORTH DAKOTA. THE FOG SHOULD BEGIN TO DISSIPATE BY THE MID TO LATE MORNING HOURS AS VERTICAL MIXING COMMENCES. UPDATE ISSUED AT 636 AM CDT SAT AUG 17 2013 THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST. REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST. THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700 TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES SHOULD MINIMIZE THE HAIL THREAT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT AUG 17 2013 POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW. FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA. ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND 00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN 2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK EVOLVE IN FUTURE FORECASTS. FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT. EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND THE APPROACH OF A WEAK SHORTWAVE. FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH. THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING THE ECMWF. BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 103 PM CDT SAT AUG 17 2013 VFR CONDITIONS WILL PREVAIL ACROSS NORTH DAKOTA THROUGH THE TAF PERIOD. THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS NEAR KMOT THIS EVENING. CONFIDENCE IS LOW REGARDING AVIATION IMPACTS. THEREFORE...ONLY INCLUDED VCTS IN THE KMOT TAF BETWEEN 00Z-05Z. FURTHERMORE...IFR CIGS/VSBYS COULD DEVELOP NEAR KJMS BETWEEN 11Z- 13Z. CONFIDENCE IS LOW IN THIS MATERIALIZING AND WILL THEREFORE LEAVE OUT OF THE KJMS TAF FOR NOW. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TM SHORT TERM...CK LONG TERM...KS AVIATION...AC
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1041 AM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 1041 AM CDT SAT AUG 17 2013 LOW CLOUDS AND PATCHY FOG ARE LINGERING OVER SOUTH CENTRAL AND SOUTHEASTERN NORTH DAKOTA LONGER THAN ANTICIPATED. AS A RESULT...UPDATED THE FORECAST TO CONTINUE THE CLOUDY AND PATCHY FOG CONDITIONS PRIMARILY ACROSS THE JAMES RIVER BASIN THROUGH THE MID-DAY HOURS. THIS SHOULD ALSO HAMPER MORNING TEMPERATURE WARMING TRENDS. HOWEVER...ONCE THE LOW CLOUDS AND FOG BURN OFF...TEMPERATURES SHOULD RAPIDLY INCREASE THIS AFTERNOON. UPDATE ISSUED AT 830 AM CDT SAT AUG 17 2013 SENT OUT A QUICK UPDATE TO INCREASE FOG COVERAGE OVER THE JAMES RIVER BASIN THROUGH THE MID-MORNING HOURS. EVEN THOUGH SURFACE WINDS ARE AROUND 10 KNOTS...AREAS OF FOG...DENSE AT TIMES...CONTINUE TO DEVELOP OVER PORTIONS OF SOUTHCENTRAL AND SOUTHEASTERN NORTH DAKOTA. THE FOG SHOULD BEGIN TO DISSIPATE BY THE MID TO LATE MORNING HOURS AS VERTICAL MIXING COMMENCES. UPDATE ISSUED AT 636 AM CDT SAT AUG 17 2013 THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST. REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST. THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700 TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES SHOULD MINIMIZE THE HAIL THREAT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT AUG 17 2013 POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW. FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA. ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND 00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN 2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK EVOLVE IN FUTURE FORECASTS. FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT. EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND THE APPROACH OF A WEAK SHORTWAVE. FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH. THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING THE ECMWF. BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 636 AM CDT SAT AUG 17 2013 IFR/LIFR CONDITIONS IN LOW CLOUDS OVER KBIS-KJMS WILL GRADUALLY IMPROVE TO VFR BY MIDDAY. ONCE THE FOG AND STRATUS EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL BOUNDARY CROSSES THE AREA. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TM SHORT TERM...CK LONG TERM...KS AVIATION...TM
AREA FORECAST DISCUSSION
NWS BISMARCK ND
830 AM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 830 AM CDT SAT AUG 17 2013 SENT OUT A QUICK UPDATE TO INCREASE FOG COVERAGE OVER THE JAMES RIVER BASIN THROUGH THE MID-MORNING HOURS. EVEN THOUGH SURFACE WINDS ARE AROUND 10 KNOTS...AREAS OF FOG...DENSE AT TIMES...CONTINUE TO DEVELOP OVER PORTIONS OF SOUTHCENTRAL AND SOUTHEASTERN NORTH DAKOTA. THE FOG SHOULD BEGIN TO DISSIPATE BY THE MID TO LATE MORNING HOURS AS VERTICAL MIXING COMMENCES. UPDATE ISSUED AT 636 AM CDT SAT AUG 17 2013 THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST. REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST. THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700 TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES SHOULD MINIMIZE THE HAIL THREAT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT AUG 17 2013 POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW. FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA. ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND 00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN 2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK EVOLVE IN FUTURE FORECASTS. FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT. EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND THE APPROACH OF A WEAK SHORTWAVE. FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH. THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING THE ECMWF. BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 636 AM CDT SAT AUG 17 2013 EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS AND FOG APPROACHING KJMS. EXPECT A CEILING AT KJMS TO ARRIVE SOON AND BE BELOW 1KFT. WILL NOT GO TOO LOW WITH VISIBILITIES SINCE MOST SPOTS ACROSS SOUTH DAKOTA IN THE STRATUS HAVE BEEN IN THE 3-5SM RANGE. WILL ALSO SHOW A VISIBILITY REDUCTION AT KBIS THIS MORNING WITH SCATTERED CLOUDS AROUND 500 FT. ONCE THE FOG AND STRATUS EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL BOUNDARY CROSSES THE AREA. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TM SHORT TERM...CK LONG TERM...KS AVIATION...CK
AREA FORECAST DISCUSSION...CORRECTED
NWS BISMARCK ND
645 AM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 636 AM CDT SAT AUG 17 2013 THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 14Z FOLLOWED BY A GRADUAL DISSIPATION THROUGH 18Z. THUS HAVE ADJUSTED SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST. REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST. THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700 TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES SHOULD MINIMIZE THE HAIL THREAT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT AUG 17 2013 POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW. FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA. ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND 00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN 2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK EVOLVE IN FUTURE FORECASTS. FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT. EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND THE APPROACH OF A WEAK SHORTWAVE. FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH. THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING THE ECMWF. BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 636 AM CDT SAT AUG 17 2013 EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS AND FOG APPROACHING KJMS. EXPECT A CEILING AT KJMS TO ARRIVE SOON AND BE BELOW 1KFT. WILL NOT GO TOO LOW WITH VISIBILITIES SINCE MOST SPOTS ACROSS SOUTH DAKOTA IN THE STRATUS HAVE BEEN IN THE 3-5SM RANGE. WILL ALSO SHOW A VISIBILITY REDUCTION AT KBIS THIS MORNING WITH SCATTERED CLOUDS AROUND 500 FT. ONCE THE FOG AND STRATUS EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL BOUNDARY CROSSES THE AREA. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KS SHORT TERM...CK LONG TERM...KS AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
636 AM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 636 AM CDT SAT AUG 17 2013 THE LATEST FOG/STRATUS LOOP SHOWS LOW CLOUDS WITH CEILINGS LESS THAN 1000FT ALONG WITH PATCHY FOG QUICKLY EXPANDING OVER THE SOUTHERN JAMES RIVER VALLEY AND MOVING NORTH WITH TIME. JAMESTOWN AND BISMARCK WILL SOON SEE SOME OF CLOUDS AND FOG. LATEST HRRR CEILING FORECAST SHOWS A NORTHWARD EXPANSION THROUGH ABOUT 13Z THEN BEGINNING TO DISSIPATED THROUGH 18Z. THUS HAVE ADJUSTED SKY GRIDS THIS UPDATE BASED ON SATELLITE AND THE HRRR FORECAST. REST OF THE SENSIBLE WEATHER ELEMENTS ARE ON TRACK. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST. THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700 TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES SHOULD MINIMIZE THE HAIL THREAT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT AUG 17 2013 POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW. FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA. ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND 00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN 2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK EVOLVE IN FUTURE FORECASTS. FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT. EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND THE APPROACH OF A WEAK SHORTWAVE. FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH. THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING THE ECMWF. BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 636 AM CDT SAT AUG 17 2013 EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS AND FOG APPROACHING KJMS. EXPECT A CEILING AT KJMS TO ARRIVE SOON AND BE BELOW 1KFT. WILL NOT GO TOO LOW WITH VISIBILITIES SINCE MOST SPOTS ACROSS SOUTH DAKOTA IN THE STRATUS HAVE BEEN IN THE 3-5SM RANGE. WILL ALSO SHOW A VISIBILITY REDUCTION AT KBIS THIS MORNING WITH SCATTERED CLOUDS AROUND 500 FT. ONCE THE FOG AND STRATUS EXIT...WILL CARRY VFR AT ALL AERODROMES INTO TONIGHT. THERE IS SOME CONCERN AN ISOLATED THUNDERSTORM COULD IMPACT KMOT OR KDIK TONIGHT...BUT AM NOT CONFIDENT ENOUGH TO PUT THOSE INTO THE FORECAST. WINDS WILL BE FROM A SOUTHERLY DIRECTION THIS MORNING...BUT WESTERN LOCATIONS WILL TURN NORTHERLY AS A FRONTAL BOUNDARY CROSSES THE AREA. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...KS SHORT TERM...CK LONG TERM...KS AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
324 AM CDT SAT AUG 17 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE MAIN CONCERNS FOR THE SHORT TERM PERIOD WILL BE FOG THIS MORNING...FOLLOWED BY CHANCES FOR THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS STRATUS / FOG EXPANDING ACROSS PARTS OF EASTERN SOUTH DAKOTA. THE NAM SUGGESTS THE FOG / STRATUS COULD EXPAND INTO SOUTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY EARLY THIS MORNING...WHICH IS ALSO IN LINE WITH THE LATEST HRRR. WILL CONTINUE TO CARRY PATCHY FOG TO COVER THIS SCENARIO. CONDITIONS WILL HAVE TO BE MONITORED IN CASE THE FOG BECOMES MORE WIDESPREAD THAN CURRENTLY FORECAST. THE NEXT CONCERN WILL BE THE CHANCES OF CONVECTION AS A FRONTAL BOUNDARY DROPS INTO WESTERN NORTH DAKOTA TODAY / TONIGHT. H700 TEMPERATURES WILL BE QUITE WARM AT +12 TO +14 CELSIUS THIS AFTERNOON / EVENING...HOWEVER FORECAST SOUNDINGS SUGGEST MIXING LATE THIS AFTERNOON COULD BE SUFFICIENT TO ERODE THE CAP NEAR THE BOUNDARY. ANOTHER FACTOR TO CONSIDER WILL BE THE ARRIVAL OF THE LEFT EXIT REGION OF AN UPPER JET STREAK MOVING INTO FAR NORTHERN NORTH DAKOTA LATE THIS AFTERNOON INTO TONIGHT. THINK THERE IS AT LEAST A SLIGHT CHANCE FOR CONVECTION ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE STATE TONIGHT...CLOSER TO THE UPPER FORCING...AND HAVE INTRODUCED POPS INTO THE FORECAST. IT APPEARS THE MAIN THREAT FROM ANY POTENTIAL STORMS WOULD BE GUSTY WINDS DUE TO INVERTED-V TYPE SOUNDINGS...WHILE WARM MID LEVEL TEMPERATURES SHOULD MINIMIZE THE HAIL THREAT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 324 AM CDT SAT AUG 17 2013 POTENTIAL FOR SEVERE WEATHER LATE SUNDAY AFTERNOON/EVENING IS THE MAIN HIGHLIGHT FOR THE EARLY PART OF THE EXTENDED. A PROGRESSIVE WEST TO SOUTHWEST FLOW IS FORECAST FOR THE REST OF THE WEEK. NOT A LOT OF WIDESPREAD ACTIVITY...BUT ENOUGH INSTABILITY AND FAST MOVING DISTURBANCES TO INITIATE ISOLATED TO SCATTERED CONVECTION. THE GFS/ECMWF DEPART ON SOLUTIONS BY MID TO LATE WEEK...BUT COME BACK IN LINE TOWARD THE END OF THE LONG TERM WITH A MORE ACTIVE SOUTHWEST FLOW. FOR SUNDAY...CONCERN IS A SURFACE LOW PRESSURE AND AN ASSOCIATED COLD FRONT STRETCHING FROM SOUTHWEST INTO CENTRAL NORTH DAKOTA. ANYWHERE ALONG AND AHEAD OF THE FRONT VIA THE WARM SECTOR WILL BE A CONCERN. THE NAM/GFS SOUNDINGS INDICATE A CAP INITIALLY IS IN PLACE FOR KBIS/KJMS AT 18Z SUNDAY...BUT ERODES IT BETWEEN 22Z SUNDAY AND 00Z MONDAY. INSTABILITY WILL BE PERCOLATING THROUGH THE DAY WITH STRONG 0-6KM BULK SHEAR OF 30KT TO 40KT...AND CAPE RANGING BETWEEN 2000-3000 J/KG...ESPECIALLY OVER SOUTH CENTRAL AND THE JAMES RIVER VALLEY. COUPLE OF INCOMING SHORTWAVES BY LATE AFTERNOON SHOULD BE ENOUGH TO REMOVE THE CAP AND ALLOW CONVECTION TO DEVELOP NEAR/ALONG THE AFOREMENTIONED FRONT. NOT ONLY WILL HAIL BE A THREAT...BUT WILL NEED TO WATCH CLOSELY FOR SEVERE WINDS...AS THE WIND INDEX/WINDEX ON BOTH THE NAM/GFS SOUNDINGS ARE FAVORABLE FOR FOR MICROBURST WINDS...BETWEEN 50KT-60KT. SPC CONTINUES TO ADVERTISE WESTERN AND CENTRAL NORTH DAKOTA IN A SEE TEXT AREA ONLY...BUT GIVEN THE SHORTWAVES ALOFT...STRONG INSTABILITY...AND A SURFACE FRONT FOR A CONVERGENCE/INITIATION...WOULD NOT BE SURPRISED TO SEE A SLIGHT RISK EVOLVE IN FUTURE FORECASTS. FOR MONDAY...THE SHORTWAVES AND SURFACE FRONT SHIFT EAST. BROAD RIDGING DURING THE DAY GIVES WAY TO A WESTERLY FLOW MONDAY NIGHT. EXPECTING A DRY DAY MONDAY...WITH A POSSIBLE SHOWER/THUNDERSTORM OVER SOUTHERN NORTH DAKOTA MONDAY NIGHT ALONG A SURFACE TROUGH AND THE APPROACH OF A WEAK SHORTWAVE. FOR TUESDAY...ATTENTION TURNS TOWARD A COLD FRONT DROPPING SOUTH FROM CENTRAL AND SOUTHERN CANADA. THE FRONT SHIFTS SOUTH TUESDAY NIGHT WITH PRECIPITATION CHANCES INCREASING OVER SOUTHERN NORTH DAKOTA TUESDAY NIGHT THROUGH WEDNESDAY. COOLER AIR TO FOLLOW FOR WEDNESDAY WITH H85 TEMPS RANGING BETWEEN +16C NORTH TO +20C SOUTHWEST...THUS HIGHS AROUND 80 NORTH TO UPPER 80S/NEAR 90 SOUTH. THE STRONGEST SHORTWAVE AND HIGH PRECIPITATION CHANCES MAY OCCUR WEDNESDAY NIGHT AND THURSDAY...PER ECMWF. A SOUTHWEST FLOW WITH AN EMBEDDED SHORTWAVE AND SURFACE FRONT SHIFTING ACROSS SOUTH DAKOTA FOCUS A DECENT AREA OF SHOWERS/THUNDERSTORMS OVER WESTERN AND CENTRAL NORTH DAKOTA. THE GFS IS MAINLY VOID OF THIS IDEA WITH A BROAD RIDGE IN PLACE. THE ALLBLEND IS A SPLIT BETWEEN THE SOLUTIONS BUT FAVORING THE ECMWF. BY FRIDAY AND SATURDAY...A MORE ENERGETIC SOUTHWEST FLOW IS FORECAST TO PUSH SHORTWAVES AND ADDITIONAL CHANCES OF PRECIPITATION INTO WESTERN AND CENTRAL NORTH DAKOTA. HIGH TEMPERATURES REMAIN MAINLY IN THE 80S FROM WEDNESDAY THROUGH FRIDAY. OVERNIGHT LOWS WILL BE IN THE UPPER 50S TO MID 60S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 324 AM CDT SAT AUG 17 2013 THE POTENTIAL FOR FOG AND LOW CLOUDS AT KJMS AND KBIS ARE THE PRIMARY CONCERNS FOR THE 06Z FORECAST. AREAS JUST EAST OF KJMS HAVE BECOME NEARLY SATURATED AT THE SURFACE WITH LOW TEMPERATURE / DEWPOINT SPREADS EARLY THIS MORNING. THE LATEST HRRR AND NAM NUMERICAL GUIDANCE SUGGESTS THERE COULD BE FOG DEVELOPMENT AT KJMS...AND WILL SHOW THAT IN THE LATEST TAF. LESSER CHANCES FOR VISIBILITY REDUCTIONS ARE SHOWN AT KBIS...AND WILL CARRY VCFG TO SUGGEST FOG COULD BE IN THE AREA EARLY THIS MORNING. THE REMAINDER OF THE FORECASTS WILL BE VFR. WINDS WILL BE FROM A SOUTHERLY DIRECTION TO START...BUT WESTERN AERODROMES WILL SEE A SHIFT TO THE NORTHWEST LATER IN THE PERIOD AS A FRONTAL BOUNDARY MOVES INTO THE REGION. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...CK LONG TERM...KS AVIATION...CK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1225 AM CDT SAT AUG 17 2013 .UPDATE... ISSUED AT 1225 AM CDT SAT AUG 17 2013 EARLY MORNING 11-3.9 MICRON SATELLITE IMAGERY SHOWS PATCHY STRATUS IN EASTERN SOUTH DAKOTA HAS DIMINISHED OVER THE PAST FEW HOURS. THE LATEST HOURLY TEMPERATURE / DEWPOINT PLOT SHOWS AREAS JUST EAST OF THE FORECAST AREA HAVE BECOME NEARLY SATURATED...AND WOULD EXPECT ADJACENT AREAS IN THE JAMES RIVER VALLEY TO SHOW A SIMILAR TREND EARLY THIS MORNING. THE GOING FORECAST ALREADY HAS PATCHY FOG IN THAT AREA...AND AFTER LOOKING AT THE HRRR DECIDED TO EXPAND THE FOG A LITTLE FARTHER WEST. WILL ADJUST THE TEMPERATURE / DEWPOINT SPREADS ACCORDINGLY...OTHERWISE MADE ONLY MINOR ADJUSTMENTS TO THE GRIDS. UPDATE ISSUED AT 924 PM CDT FRI AUG 16 2013 MINOR CHANGES IN HOURLY TEMPERATURES TO REFLECT CURRENT TRENDS. OTHERWISE ONGOING FORECAST FOR TONIGHT IS ON TRACK. CLEAR SKIES AND SOUTH WINDS EXPECTED FOR THE REST OF TONIGHT...EXCEPT THE POSSIBILITY OF SOME FOG AND PERHAPS LOW CLOUDS MOVING INTO THE JAMES RIVER VALLEY LATE TONIGHT. LATER SHIFTS WILL MONITOR ANY FOG OR LOW CLOUDS FORMING AND MOVING NORTHWARD FROM EASTERN SOUTH DAKOTA AND NEBRASKA. UPDATE ISSUED AT 629 PM CDT FRI AUG 16 2013 SURFACE HIGH PRESSURE OVER IOWA AND LOW PRESSURE IN THE LEE OF THE ROCKIES WAS KEEPING A SOUTHERLY WIND FLOW ACROSS THE DAKOTAS. DRY AIR ALOFT WITH THE UPPER LEVEL RIDGE BUILDING WILL KEEP SKIES MOSTLY CLEAR THIS EVENING. CURRENT FORECAST ON TRACK WITH NO CHANGES. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 337 PM CDT FRI AUG 16 2013 MID/UPPER LEVEL RIDGING OVER THE WESTERN GREAT PLAINS WILL CONTINUE TO GENERATE A DRY AND TRANQUIL WEATHER PATTERN OVER WESTERN AND CENTRAL NORTH DAKOTA THROUGH THE PERIOD. WEAK GRADIENT FLOW COMBINED WITH ABUNDANT LOW-LEVEL MOISTURE SHOULD ALLOW FOR PATCHY FOG DEVELOPMENT ACROSS THE JAMES RIVER BASIN AFTER MIDNIGHT TONIGHT. IT SHOULD BE QUICK TO BURN OFF AFTER SUNRISE SATURDAY MORNING. ABOVE NORMAL TEMPERATURES ARE EXPECTED SATURDAY AS WAA DEVELOPS AHEAD OF A SURFACE TROUGH. THE SURFACE TROUGH AXIS/BOUNDARY IS PROGGED TO ENTER NORTHWESTERN NORTH DAKOTA BY SATURDAY AFTERNOON. EVEN THOUGH THERE IS ENOUGH INSTABILITY AND DEEP LAYER SHEAR FOR CONVECTIVE DEVELOPMENT...A DRY PUSH ALOFT SHOULD INHIBIT AFTERNOON CONVECTION. THEREFORE...KEPT THE FORECAST DRY NORTHWEST FOR SATURDAY AFTERNOON. HOWEVER...WOULD NOT BE SURPRISED IF A THUNDERSTORM DEVELOPED ALONG THE BOUNDARY DURING THE LATE SATURDAY AFTERNOON/EARLY EVENING HOURS. WILL CONTINUE TO MONITOR THE CAP STRENGTH AS THE TIME GETS CLOSER. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 337 PM CDT FRI AUG 16 2013 WESTERLY ZONAL FLOW WILL ESTABLISH ITSELF EARLY IN THE PERIOD...AS THE UPPER LEVEL RIDGE CONTINUES TO FLATTEN. SEVERAL EMBEDDED WEAK IMPULSES...DEPICTED BY BOTH THE 12Z ECWMF AND GFS...WILL MOVE ACROSS THE AREA SATURDAY NIGHT INTO SUNDAY. EVEN THOUGH THERE WILL BE AMPLE CAPE...SUFFICIENT DEEP LAYER SHEAR AND MODEST BOUNDARY LAYER MOISTURE...12Z NAM/GFS BUFR SOUNDINGS CONTINUE TO SUGGEST THAT A WARM LAYER WILL BE PRESENT ALOFT...ENOUGH TO SUPPRESS CONVECTION FROM FIRING ACROSS THE NORTHWEST BETWEEN 00Z AND 06Z SUNDAY. THE WARM LAYER ALOFT/CAPPING INVERSION MAY BE OVERCOME ONCE THE AFOREMENTIONED IMPULSES TRAVERSE THE AREA SUNDAY AND EARLY MONDAY...ALLOWING CONVECTION TO FIRE ALONG AND AHEAD OF A WEAK COLD FRONT FORECAST TO MOVE SOUTH. HAVE OPTED TO LEAVE SLIGHT CHANCE POPS IN FOR NOW AND WILL CONTINUE TO MONITOR OVER THE NEXT FEW MODEL RUNS. MONDAY AND TUESDAY...WESTERLY ZONAL FLOW CONTINUES. EVEN WITH THE WEAK COLD FRONTAL PASSAGE...H850 TEMPERATURES WILL REMAIN WARM BETWEEN 20 TO 22 C...WARMING TO BETWEEN 24 AND 26 C TUESDAY WHILE THE UPPER LEVEL RIDGE NUDGES NORTH. THIS WILL TRANSLATE TO SURFACE TEMPERATURES IN THE 90S. SIGNIFICANT DIFFERENCES DEVELOP BETWEEN THE 12Z GFS AND ECWMF WEDNESDAY AND CONTINUES THROUGH THE REMAINDER OF THE PERIOD REGARDING A STRONG COLD FRONTAL PASSAGE. THE 12Z ECWMF IS MORE AGGRESSIVE PROPAGATING THIS FEATURE SOUTH WEDNESDAY...SUGGESTING THAT SURFACE HIGH PRESSURE FROM CANADA WILL BUILD SOUTH IN ITS WAKE AND COOLING H850 TEMPS BY OVER TEN DEGREES C. HOWEVER...THE 12Z GFS DELAYS THE PASSAGE OF THE COLD FRONT UNTIL THURSDAY MORNING/AFTERNOON. AS A CONSEQUENCE...THERE IS A 10C DIFFERENCE BETWEEN THESE MODELS WEDNESDAY...AND THURSDAY ACROSS THE SOUTH...WITH THE GFS CONTINUING 20 TO 22 C H850 TEMPS (MID TO UPPER 90S AND ISOLATED 100 DEGREE READINGS AT THE SURFACE)...WHILE THE ECWMF SUGGESTS AN END TO THE HEAT...COOLING H850 TEMPS TO BETWEEN 14 TO 17 C (80S AT THE SURFACE WEDNESDAY AND COOLING TO THE 70S ON THURSDAY). THUS HAVE STUCK WITH THE ALLBLEND SOLUTION GIVEN THE SIGNIFICANT DISAGREEMENT BETWEEN THE GFS AND ECWMF. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1225 AM CDT SAT AUG 17 2013 THE POTENTIAL FOR FOG AND LOW CLOUDS AT KJMS AND KBIS ARE THE PRIMARY CONCERNS FOR THE 06Z FORECAST. AREAS JUST EAST OF KJMS HAVE BECOME NEARLY SATURATED AT THE SURFACE WITH LOW TEMPERATURE / DEWPOINT SPREADS EARLY THIS MORNING. THE LATEST HRRR AND NAM NUMERICAL GUIDANCE SUGGESTS THERE COULD BE FOG DEVELOPMENT AT KJMS...AND WILL SHOW THAT IN THE LATEST TAF. LESSER CHANCES FOR VISIBILITY REDUCTIONS ARE SHOWN AT KBIS...AND WILL CARRY VCFG TO SUGGEST FOG COULD BE IN THE AREA EARLY THIS MORNING. THE REMAINDER OF THE FORECASTS WILL BE VFR. WINDS WILL BE FROM A SOUTHERLY DIRECTION TO START...BUT WESTERN AERODROMES WILL SEE A SHIFT TO THE NORTHWEST LATER IN THE PERIOD AS A FRONTAL BOUNDARY MOVES INTO THE REGION. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CK SHORT TERM...TM LONG TERM...LTH AVIATION...CK
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
1135 PM CDT FRI AUG 16 2013 .UPDATE... ISSUED AT 1135 PM CDT FRI AUG 16 2013 TEMPS HAVE BEEN FALLING A BIT FASTER THAN EXPECTED IN THE NORTHWESTERN COUNTIES...SO CUT LOWS A FEW DEGREES IN THAT AREA. WINDS CONTINUE TO BE SOUTHERLY IN DIRECTION...AND THERE HAS BEEN SOME DECENT MIXING. DEW POINT DEPRESSIONS HAVE BEEN CLOSE TO ZERO AROUND VALLEY CITY AND COOPERSTOWN. STILL THINK THAT THE BEST CHANCE FOR FOG WILL BE IN THE JAMES RIVER VALLEY...BUT SOME IN OUR SOUTHWESTERN COUNTIES IS NOT OUT OF THE QUESTION. INCLUDED A BRIEF PATCHY MENTION DURING THE EARLY MORNING HOURS. UPDATE ISSUED AT 932 PM CDT FRI AUG 16 2013 NO MAJOR CHANGES TO THE CURRENT FORECAST. TEMPS STILL SEEM ON TRACK TO DROP INTO THE 50S IN THE EAST TO LOW 60S OVERNIGHT. SOME OF THE MODELS SUCH AS THE HRRR AND NAM ARE SHOWING SOME FOG FORMATION OVER THE JAMES VALLEY WHICH THEN MOVES INTO OUR SOUTHWESTERN COUNTIES BRIEFLY LATER TONIGHT. SOUTHWESTERLY WINDS WILL BE PICKING UP AND THINK THAT MIXING WILL KEEP MUCH FOG FROM FORMING AND WILL LEAVE OUT OF GRIDS FOR NOW. THINK THERE COULD BE SOME STRATUS THROUGH SO KEPT SOME CLOUDS IN THE FAR SOUTH. UPDATE ISSUED AT 627 PM CDT FRI AUG 16 2013 ONLY CHANGES WERE TO TWEAK CLOUD COVER A BIT AS SOUTHERN COUNTIES HAVE HAD A BIT MORE CU THAN EXPECTED THIS EVENING. THINK THAT SKIES WILL BECOME MOSTLY CLEAR AFTER SUNSET...BUT WILL HAVE TO WATCH THE SOUTH FOR ANY STRATUS MOVING UP OUT OF SD. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 242 PM CDT FRI AUG 16 2013 CURRENT VIS IMAGERY SHOWING SCT CU DECK HAS EXPANDED WESTWARD INTO SOUTHEASTERN ND. MOSTLY CLEAR ELSEWHERE. THERE IS MORE EXTENSIVE SKY COVER OVER EASTERN SD AND FAR SW MINNESOTA....HOWEVER THE NORTHERN EDGE CONTINUES TO BECOME MORE CELLULAR. MAIN CHALLENGE TONIGHT WILL BE TEMPERATURES AND WHETHER OR NOT THE LOW LEVEL SW FLOW WILL ADVECT ANY OF THIS MOISTURE INTO MY SOUTHEASTERN ZONES. MODELED RH IN GENERAL AGREEMENT WITH BRINGING CLOUD COVER NORTHWARD BUT NO SIGNS OF CLOUDS ON GFS/NAM MOS GUIDANCE. LATE AFTERNOON AND TONIGHT...FOR CLOUD SITUATION...THINK LAST COUPLE HOURS OF HEATING THIS AFTN WILL CONTINUE TO BREAK CLOUDS UP ENOUGH OVER SD THAT THEY WILL DISSIPATE IN THE EARLY EVENING AND WE WILL BE CLEAR TONIGHT ACROSS THE AREA. OVERNIGHT LOWS WILL BE A BIT WARMER THAN LAST NIGHT WITH SOUTHERLY FLOW EXPECTED THROUGH THE NIGHT. SATURDAY AND SATURDAY NIGHT...FULL SOLAR...BREEZY SOUTHWEST WINDS AND INCREASED MIXING AS WELL AS RISING H850 TEMPS WILL RESULT IN THE FIRST ABOVE NORMAL TEMPS FOR AUGUST 2013. COULD EVEN HIT 90 IN WARM AREAS AROUND THE VALLEY. MODELS ARE SHOWING A CHANCE FOR SOME SHOWERS OR A STORM TO DEVELOP MAINLY ACROSS THE NORTH AND AFTER 09Z. HOWEVER MAIN ENERGY WITH UPPER WAVE SHOULD BE ACROSS SOUTHERN MANITOBA AND WILL KEEP CWA DRY TONIGHT. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 242 PM CDT FRI AUG 16 2013 SUNDAY AND MONDAY...ANOTHER WARM DAY IS EXPECTED WITH INSTABILITY INCREASING IN THE AFTERNOON BUT A SOLID CAP IN PLACE. MERIDIONAL FLOW WILL BRING SEVERAL MINOR WAVES ACROSS THE AREA...HOWEVER TIMING NOT CONSISTENT ENOUGH AMONGST THE MODELS TO ADD ANY POPS THROUGH 00Z MON. BEST CHANCE WILL BE IN THE EVENING IF AND WHEN THE CAP ERODES. WITH MAIN H850 FLOW OVER THE WKND OUT OF WESTERN TX/NM VS AN OPEN GULF OF MEXICO...NOT SURE DEW POINTS WILL GET HIGH ENOUGH DRG DAY SUNDAY TO GIVE US A SIGNIFICANT CHANCE OF CONVECTION SUN EVENING HOWEVER WITH GFS SHOWING A STRONG VORT MOVING ACROSS (BUT OVERDOING CONVECTION)...WILL STICK WITH CONTINUITY AND MAINTAIN CHANCE POPS MAINLY ACROSS THE SOUTH. ONCE AGAIN CONFIDENCE FOR ANYTHING SIGNIFICANT IS LOW ATTM. EXPECT MONDAY TO BE DRY. MONDAY THROUGH FRIDAY...MODELS ARE DECENT WITH OVERALL FEATURES WITH SOME DIFFERENCES TO TIMING OF CONVECTIVE CHANCES. THE GFS/ECMWF WANTS TO DEVELOP SOME STORMS BY WED/THU...WITH THE GEM REMAINING DRY THROUGH THE PERIOD. THERE WILL BE VERY WARM TEMPS ALOFT AND TEMPS WILL REMAIN WELL ABOVE NORMAL. IF THE ATMOSPHERE REMAINS CAPPED...THEN THIS WOULD LIMIT CONVECTIVE CHANCES. WE HAVE ALSO BEEN DRY FOR SOME TIME...AND OVERALL EVAPOTRANSPIRATION WILL BE QUITE LOW. IN ADDITION...THE GULF OF MEXICO REMAINS SHUT OFF...SO THIS COULD ALSO LIMIT SHOWER/STORMS UNTIL A STRONGER WAVE MOVES OVER THE AREA. WILL CONTINUE WITH LOWER CHANCES FOR STORMS BY MID WEEK...ALTHOUGH CONFIDENCE IS NOT VERY HIGH FOR WIDESPREAD RAINFALL. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1135 PM CDT FRI AUG 16 2013 ANY LOWER CIGS AND VIS SHOULD STAY SOUTH OF THE TAF SITES WITH VFR CONDITIONS PREVAILING AND SOME MID AND HIGH CLOUDS. SOUTH WINDS AROUND 10 KTS WILL PICK UP BY MID MORNING WITH GUSTS UP TO 25 KTS POSSIBLE. WINDS SHOULD DIMINISH AGAIN TOMORROW EVENING. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ UPDATE...JR SHORT TERM...SPEICHER LONG TERM...DK/SPEICHER AVIATION...JR
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1013 PM EDT SUN AUG 18 2013 .SYNOPSIS... SEVERAL WEAK WEATHER SYSTEMS WILL DRIFT SLOWLY THROUGH THE GREAT LAKES FROM TONIGHT THROUGH MID-WEEK...AS TEMPERATURES AND HUMIDITY CONTINUE TO SLOWLY INCREASE AT THE SAME TIME. NEITHER OF THE DISTURBANCES IS EXPECTED TO BRING MUCH COVERAGE OF RAIN...BUT THREATS FOR SHOWERS OR A FEW THUNDERSTORMS ON A LIMITED BASIS WILL BE PRESENT TONIGHT INTO MONDAY MAINLY EAST OF I-71...AND ON WEDNESDAY ESPECIALLY SOUTH OF I-70. IN BOTH CASES...MOST AREAS WILL STAY DRY...WITH MUGGY AND WARM AFTERNOONS AND MILD NIGHTS WITH LIGHT WINDS. ABOVE NORMAL TEMPERATURES WILL REMAIN ENTRENCHED THROUGH THE WEEK INTO NEXT WEEKEND...AS A VERY TYPICAL LATE SUMMER PATTERN REMAINS IN PLACE. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... UPDATED TONIGHT TO REMOVE ALL PRECIPITATION FOR THE OVERNIGHT HOURS. WITH LOSS OF HEATING OF THE DAY AND WEAK FORCING REMAINING...THERE IS ONLY SMALL CHANCE OF SHOWERS. ALSO ADJUSTED SKY COVER FOR CURRENT TRENDS. NO OTHER SIGNIFICANT CHANGES WERE MADE WITH THIS UPDATE. AFTERNOON DISCUSSION FOLLOWS BELOW.... DISORGANIZED SHIELD OF VERY LIGHT RAIN/SPRINKLES HAS BEEN PUSHING STEADILY NORTHEAST THROUGH THE AFTERNOON UP THE SCIOTO RIVER VALLEY...IMMEDIATELY IN ADVANCE OF A MID-LEVEL VORTICITY MAX SEEN SWIRLING BOTH ON VISIBLE SATELLITE IMAGERY AND ON RADAR MOSAICS OVER NRN KENTUCKY. THIS IS NEAR THE NOSE OF A NARROW 250MB JETLET /115KT/ THAT IS SHIFTING NORTHEAST AND ALLOWING THE OPENING/SHEARING OF THE OLD CLOSED LOW THAT HAD BEEN SPINNING WELL SOUTHWEST OF THE AREA THE PAST FEW DAYS. THE MID/UPPER LEVEL SHORTWAVE TROUGH IS POSITIVELY TILTED...AND WEAKENING WITH TIME...WITH DECREASING LARGE SCALE ASCENT AND VERY WEAK SURFACE FEATURES UNDERNEATH. THE 18.18Z RAP HAD A NICE HANDLE ON THE MID LEVEL VORT MAX DRIVING NORTHEAST THROUGH SCNTL OH...AND CONTINUES TO LIFT THIS FEATURE OUT OF THE AREA THROUGH MID EVENING...WITH THE SHIELD OF LIGHT RAIN/SPRINKLES LIKELY EXITING THE AREA BY 00Z OR SO...IF IT DOESN/T FALL APART COMPLETELY BEFORE THEN. MESOANALYSIS CURRENTLY /19Z/ SHOWS A FAIRLY NICE DIFFERENTIAL HEATING ZONE /CAPE AXIS/ ON THE IMMEDIATE WEST SIDE OF THE RAIN SHIELD...RUNNING FROM OWEN/GRANT COUNTIES UP THROUGH THE WILMINGTON AREA TOWARDS CMH. VARIOUS AND SUNDRY CONVECTION ALLOWING MODEL RUNS /3-4KM RESOLUTION/ HAVE TRIED TO DEVELOP ISOLATED STORMS IN THIS CORRIDOR IN THE NEXT FEW HOURS UP THROUGH ABOUT 02Z...SO WE ARE IN NO HURRY TO DECREASE/SHRINK RAIN CHANCES WEST OR SOUTHWEST OF CURRENT RAIN SHIELD OVER SCNTL OH. WHILE MLCAPE IS LARGELY WEAK /300-700 J/KG/...THE PASSING OF THE MID/UPPER LEVEL PV ANOMALY ACROSS THIS AREA THROUGH THE NEXT FEW HOURS MAY AGITATE THE WEAK BAROCLINIC ZONE FOR A STORM OR TWO. LATER THIS EVENING/OVERNIGHT...ONE MORE SURGE /IF YOU CAN CALL IT THAT - IT IS QUITE WEAK/ OF MOISTURE ADVECTION RIDES FROM ERN TN/KY INTO CNTL/ERN OH AND MAY PROMOTE SOME -SHRA REGENERATION OVER THE SCIOTO VALLEY AND UP TOWARD/EAST OF CMH...SO WE HOLD ON TO HIGHER RAIN CHANCES HERE LATER THIS EVENING AND OVERNIGHT. NOT SURE IF THIS WILL LEAD TO MUCH ACTIVITY OR NOT...CONFIDENCE IS LOW...BUT THE SIGNAL HAS BEEN PRESENT FOR A FEW DAYS THUS DON/T WANT TO BACK AWAY YET. KEPT MIN TEMP FORECAST RIGHT WHERE IT WAS FOR THE MOST PART...WELL TRENDED IN THE LOWER 60S MOST AREAS...THOUGH MIXED OUT DEW POINTS IN WCNTL OHIO/ERN IND SUGGEST SOME MID TO UPPER 50S IN THAT AREA WHERE PRECIPITABLE WATER MINIMUM EXISTS. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... THE LAST WEAK SURGE OF MOISTURE MAY LINGER SHOWER CHANCES IN THE EAST IN THE MORNING...AND THERE MAY BE JUST ENOUGH DIURNAL INSTBY FOR A SHOWER/STORM IN THE FAR EAST/SOUTH IN THE AFTERNOON...BUT MONDAY IS LARGELY A DRY DAY FOR THE FORECAST AREA WITH INCREASING SUBSIDENCE IN THE WAKE OF THE DEPARTING SHORTWAVE TROUGH WHICH WILL BE SHEARING DOWNSTREAM THROUGH PA/NY. DESPITE ITS DEPARTURE...THERE REMAINS A WEAKNESS IN THE LARGER SCALE HEIGHT FIELD BETWEEN TWO LARGE ANTICYCLONES OFF THE SOUTHEAST CONUS AND OVER THE CNTL CONUS. THIS WEAKNESS IS A SOURCE OF LINGERING WEAK SHORTWAVE ENERGY...AND WITH THIS AXIS LINGERING IN THE FAR SOUTH/EAST...THUS THE SMALL RAIN CHANCES LINGERING UNTIL THAT AXIS CAN CLEAR IN THE MID AFTERNOON HOURS. MOST AREAS WILL SEE A FAIR AMOUNT OF SUNSHINE ON MONDAY...WITH TEMPS ADDING A FEW MORE DEGREES TO PUT MOST AREAS IN THE LOW-MID 80S. BRIEF SHORTWAVE RIDGING SLIDES IN FOR MONDAY NIGHT...WITH SKIES GOING CLEAR. THIS SHOULD ALLOW A LITTLE BETTER TEMP DROP WITH PWAT DROPPING OFF BACK TOWARD 1 INCH /BELOW SEASONAL NORMS/. THUS...SIDED WITH SOME OF THE MOS DATASETS THAT ALLOWED COOL SPOTS TO DROP OFF PRETTY DECENTLY MON NIGHT INTO THE UPPER 50S. WITH SUCH LIGHT WINDS OVER THE NEXT COUPLE NIGHTS...ALMOST CERTAIN TO BE COMMON SUMMER NIGHT FOG IN LOW LYING AREAS...BUT NOT SEEING A GREAT SIGNAL FOR SOMETHING WIDESPREAD TO INCLUDE IN THE FORECAST AS OF YET. && .LONG TERM /TUESDAY THROUGH SUNDAY/... SURFACE HIGH PRESSURE WILL ESTABLISH ITSELF TO OUR SE ON TUESDAY IN WAKE OF DEPARTING UPR LVL SYSTEM. WE SHOULD SEE A MOSTLY SUNNY TO PARTLY SUNNY DAY. MODELS HAD BEEN SUGGESTING THAT PERHAPS A POP OF SHOWER OR STORM COULD OCCUR IN THE FAR SOUTH DURING THE HEAT OF THE DAY. THIS STILL MAY OCCUR...BUT DO NOT FEEL IT WARRANTS A 20 POP MENTION SO HAVE ALLOW THE FORECAST TO REMAIN DRY. HIGHS WILL BE A LITTLE WARMER...GENERALLY IN THE MID 80S. FOR THE PERIOD TUESDAY NIGHT INTO WEDNESDAY NIGHT...MAJORITY OF MODELS HAVE COME MORE IN LINE ON WHAT WILL HAPPEN TO EMBEDDED S/WV ENERGY WITHIN THE NW FLOW ALOFT. IT APPEARS THIS ENERGY WILL DEVELOP INTO A CLOSED LOW TO OUR WEST...THEN WILL SLOWLY PROGRESS EAST THROUGH THE REGION WEDNESDAY INTO WEDNESDAY NIGHT. ECMWF/GFS SUGGEST THAT SOME EMBEDDED S/WV ENERGY MOVING NE AROUND DEVELOPING CLOSED LOW COULD SPARK A FEW SHOWERS AND THUNDERSTORMS BEGINNING ACRS OUR SW TUESDAY NIGHT. HAVE GIVEN ALL LOCATIONS AT LEAST A THREAT FOR SHOWERS AND STORMS ON WEDNESDAY WITH THE HIGHER CHANCES FAVORING THE SRN ZONES DUE TO HIGHER INSTABILITY AND MOISTURE. HAVE ALLOWED POPS TO FALL OFF OVERNIGHT WEDNESDAY NIGHT AS SYSTEM HEADS EAST. HIGHS ON WEDNESDAY WILL BE SLIGHTLY COOLER...ESPECIALLY SOUTHWEST CLOSER TO THE UPR LVL LOW. FOR THE PERIOD THURSDAY INTO FRIDAY NIGHT...MODELS CONTINUE TO STRUGGLE ON HOW LONG WAVE TROUGH ENERGY WILL DIG SE INTO SE CANADA AND NEW ENGLAND DURING THE PERIOD. AS SUCH...ASSOCIATED COLD FRONT AND WHERE IT WILL END UP...I.E. WILL IT PUSH THROUGH...STALL OUT OVER OUR AREA...OR PERHAPS FALL APART...IS STILL IN QUESTION. HAVE TAKEN A BLEND OF WPC AND THE LATEST 18.12Z ECMWF...WHICH ALLOWS THE FRONT TO APPROACH THE REGION FROM THE NORTH THURSDAY NIGHT...SLOW IT UP AS IT PUSHES INTO THE REMAINDER OF THE AREA ON FRIDAY...THEN WASHES IT OUT FRIDAY NIGHT INTO SATURDAY AS ANOTHER HIGH PRESSURE RIDGE BUILDS IN FROM THE NORTH. GIVEN LACK OF STRONG UPR SUPPORT...AS IT IS FCST TO REMAIN WELL OFF TO THE NE...ALONG WITH WEAK LOW LEVEL FORCING...HAVE KEPT POPS LOW THURSDAY NIGHT INTO FRIDAY. HAVE THEN ALLOWED CONDITIONS TO DRY OUT BY FRIDAY NIGHT. TEMPERATURES WILL BE CLOUD DEPENDENT BUT SHOULD SEE A SLIGHT BUMP UP AHEAD OF THE FRONT ON THURSDAY WITH SIMILAR OR SLIGHTLY COOLER CONDITIONS POSSIBLE ON FRIDAY. SURFACE HIGH PRESSURE WILL MOVE EAST THROUGH THE UPCOMING WEEKEND AS A MID LVL RIDGE BEGINS TO NUDGE INTO FROM THE CNTRL PLAINS. CONDITIONS SHOULD REMAIN DRY. TEMPERATURES WILL BE SEASONABLY WARM FOR LATE AUGUST. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... SHOWERS HAVE DISSIPATED ACROSS MUCH OF CENTRAL OHIO THIS EVENING. EARLY THIS EVENING AN AREA OF SCATTERED SHOWERS AND THUNDERSTORMS WAS MOVING NE TOWARD ILN/S NORTHERN KY COUNTIES...HOWEVER THIS CONVECTION SHOULD MISS ANY TAF SITES BEFORE DISSIPATING. THE CLOSED LOW THAT HAS BEEN SPINNING WELL SW OF THE AREA THE PAST FEW DAYS WILL CONTINUE TO OPEN AND SHEAR OVER THE NEXT 12 TO 18 HOURS. THE MID/UPPER LEVEL SHORTWAVE TROUGH IS POSITIVELY TILTED AND WEAKENING WITH TIME AS IT MOVES EAST...PROVIDING LESS SUPPORT FOR ANY SHOWERS/THUNDERSTORMS FOR THE REMAINDER OF THE TAF PERIOD. WHILE THERE IS A SLIGHT CHANCE OF SEEING A SHOWER IN THE EAST LATER TONIGHT...OPTED TO KEEP ALL TAFS DRY THROUGH THE FORECAST PERIOD. WITH THE LOSS OF DAYTIME HEATING...THE CU FIELD DIMINISHED. CLEARING AND LIGHT WINDS ARE EXPECTED AT TAF SITES OVERNIGHT AND THIS WILL BRING THE POSSIBILITY OF MVFR VSBYS IN FOG FROM 19/09Z TO 19/13Z. KLUK AND KILN MAY DEVELOP IFR VSBYS IN FOG BUT NOT CONFIDENT ENOUGH TO INCLUDE IN FORECAST AT THIS TIME. VFR CONDITIONS EXPECTED AFTER 19/13Z WITH SCATTERED CU DEVELOPING. OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...BINAU NEAR TERM...BINAU/PARKER SHORT TERM...BINAU LONG TERM...HICKMAN AVIATION...PARKER
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
953 PM EDT SUN AUG 18 2013 .SYNOPSIS... UPPER LEVEL TROUGH...AND ASSOCIATED MID LEVEL SHORT WAVES CROSS THROUGH MONDAY. SFC HIGH PRESSURE REMAINS THROUGH MID WEEK. COLD FRONT STALLS NORTH BY LATE WEEK. HIGH PRESSURE FOR NEXT WEEKEND. && .NEAR TERM /THROUGH MONDAY/... UPDATED SKIES...POPS...TEMPS...DEWPOINTS...AND WEATHER PER LATEST RADAR...SATELLITE AND SFC OBSERVATIONS. MODELS CONTINUE TO SHOW VORT MAXES PASSING FROM SOUTHWEST TO NORTHEAST ACROSS THE AREA OVERNIGHT. AN UPPER LEVEL JET STREAK EXCEEDING 80 KNOTS IS EVIDENT IN MODELS AND WATER VAPOR IMAGES...EXPECTED TO MOVE OVERHEAD OVERNIGHT. HOWEVER...WITH THE LACK OF HEATING...EXPECT ISOLATED TO SCATTERED SHOWERS THROUGH THE EARLY MORNING HOURS. DEWPOINT DEPRESSION WILL BE 1 OR 2 DEGREES APART...MEANWHILE...POCKETS OF CLEAR SKIES OR VERY HIGH LEVEL CLOUDS DEVELOP. BOUNDARY LAYER FLOW REMAINS NEAR 10 KNOTS PER THE NAM...AND AT OR BELOW 5 KNOTS PER THE RUC13. THIS SCENARIO COULD RESULT IN WIDESPREAD DENSE FOG...ESPECIALLY OVER AREAS THAT RECEIVED RAIN. DEPENDING ON CLOUD COVER EARLY MONDAY MORNING...FOG MAY HANG LONGER ACROSS PROTECTED VALLEYS. INTERPOLATED LATEST SFC OBS WITH THE 23Z RUN RUC13 FOR TEMPERATURES THROUGH 12Z MONDAY. PREVIOUS DISCUSSION BELOW... UPPER LEVEL S/W TROUGH APPROACHES TONIGHT AND THEN CROSSES MON. DISTURBANCE RIDING UP ALONG THE SW FLOW AHEAD OF THE TOUGH CROSSING THE AREA THIS AFTERNOON EXITS NE TONIGHT...RESULTING IN A DECREASE OF AREA COVERAGE OF RAIN. ABUNDANT CLOUD AND THE RAIN PRECLUDED SFC HEATING TODAY. STILL HAVE THE SMALL CHANCE FOR A LATE THUNDERSTORM TODAY...BUT THE POTENTIAL IS MUCH LOWER NOW. A SMALL PORTION OF N CENTRAL WV GOT HIT HARD WITH RAIN LAST NIGHT. GRANTSVILLE IN CALHOUN COUNTY CAME IN WITH 2.56 INCHES IN 24 HRS ENDING 12Z THIS MORNING. THIS WAS CLOSE TO IN MAGNITUDE BUT S OF THE DP STORM TOTAL BULLSEYE...WITH VALUES CLOSER TO 1.50 AT GRANTSVILLE. LEGACY STORM TOTAL WAS ABOUT 60 PERCENT OF DP. THE AREA WILL NEED WATCHED FOR A HEAVIER THUNDERSTORM INTO THIS EVENING. A SECOND WAVE RIDES UP THE MOUNTAINS MON MORNING. MODEST INSTABILITY THROUGHOUT THE AREA WITH BREAKS OF SUNSHINE UNDER THE PASSING S/W TROUGH MON AFTERNOON GIVES RISE TO THE THUNDERSTORM CHANCE. TEMPERATURES TODAY NEEDED LOWERED. LOWS TONIGHT WERE IN LINE WITH THE MET WHICH LOOKED REASONABLE. BLENDED IN THE MET TO RAISE HIGHS A BIT MON...MAINLY W. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/... QUIETER WEATHER IN THE SHORT TERM PERIOD. WARMER...AND MORE HUMID WEATHER WILL BE THE RULE ON TUESDAY...WITH SURFACE HIGH OVER THE REGION...AND BUILDING UPPER HEIGHTS OUT AHEAD OF AN UPPER SHORTWAVE TROUGH WHICH WILL MOVE INTO THE AREA IN THE WEDNESDAY NIGHT/THURSDAY TIME FRAME. WITH A CLEARING SKY MONDAY NIGHT...AND SURFACE HIGH OVER THE AREA...EXPECT RIVER VALLEY FOG DEVELOPMENT TUESDAY MORNING...PARTICULARLY ACROSS SOUTHEAST OHIO...EASTERN KY...AND ADJACENT WV COUNTIES WHERE BETTER CLEARING IS LIKELY TO TAKE PLACE. WITH THE INCREASED HEAT AND HUMIDITY ON TUESDAY...EXPECT ISOLD DIURNAL THUNDERSTORMS...MAINLY ACROSS SOUTHERN ZONES...BUT MUCH OF AREA WILL REMAIN DRY. KEPT POPS AT SLIGHT CHANCE ON TUESDAY. UPPER SHORTWAVE TROUGH TRIES TO NUDGE EAST TOWARDS THE CWA ON WEDNESDAY. THIS WILL ALLOW FOR A GREATER CHANCE OF POPS AS COMPARED TO TUESDAY...AND SLIGHTLY COOLER TEMPERATURES THAN TUESDAY. FLOW WILL REMAIN RELATIVELY LIGHT...AND WITH PW VALUES EXPECTED TO ONCE AGAIN CLIMB TO AROUND 1.6 INCHES...COULD SEE ISOLD SPOTS OF HEAVY RAIN/POTENTIAL WATER ISSUES IN PRONE AREAS. WILL ALSO KEEP MENTION OUT OF THE HWO FOR NOW AS DONT FEEL THE THREAT IS ENOUGH TO WARRANT A FFA ON WEDNESDAY. && .LONG TERM /THURSDAY THROUGH SUNDAY/... PROGRESSIVELY MORE UNCERTAIN MODEL SOLUTIONS THROUGH THE PERIOD LED TO A MODEL BLEND...GIVING SLIGHTLY MORE FAVOR TO THE ECMWF...UPPER TROUGH WEDNESDAY NIGHT MOVES OFF SHORE BY FRI MORNING WITH NORTHWEST FLOW AND EMBEDDED SHORTWAVES IN ITS WAKE...AMPLIFIED UPPER RIDGE BUILDS OVER THE EASTERN US BY SUNDAY EVENING...BEST CHANCE FOR PRECIP IS ACROSS NORTH/CENTRAL WV LATE WED/EARLY THUR WITH EXITING TROUGH RESULTING IN MARGINAL UPPER LEVEL FORCING...OTHERWISE SLIGHT CHANCE OF DIURNAL/OROGRAPHIC FORCED PRECIP IN THE EASTERN MTN AREAS LATER THURS AND FRI AFTERNOON...APPEAR TO DRY OUT NICELY FOR NEXT WEEKEND IN INCREASINGLY STABLE AIR MASS. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... MVFR/IFR CONDITIONS EXPECTED ALONG THE EASTERN MOUNTAIN TONIGHT AS ISOLATED TO SCATTERED SHOWERS CONTINUE TO MOVE NORTH NORTHEAST...TO IMPACT BKW...EKN AND CKB WITH LIGHT RAIN OVERNIGHT. POCKETS OF CLEAR SKIES...OR VERY HIGH CIRRUS COULD ALLOW FOR FOG FORMATION AS TEMPERATURES DROP TO THEIR DEWPOINTS EARLY TONIGHT. NAM AND RUN MODELS SHOW LIGHT LIGHT TO CALM FLOW IN THE BOUNDARY LAYER AND DEWPOINTS OVERNIGHT SHOULD STAY IN THE MID TO UPPER 60S. EXPECT IFR/LIFR CONDITIONS UNDER DENSE FOG AT CRW...HTS...AND PKB OVERNIGHT. IFR LOW STRATUS IS ALSO POSSIBLE IF UPPER TO MIDDLE LEVEL CLOUDS DEVELOP IN RESPONSE OF VORTICITY MAX AT H5 PASSING THROUGH...AND AN A H3 JET STREAK OVERHEAD THROUGH 12Z MONDAY. FOG AND LOW STRATUS WILL BE SLOWER TO BURN OFF OR MIX OUT MONDAY MORNING ON ACCOUNT OF THE ABUNDANT LOW LEVEL MOISTURE. SFC FLOW WILL BE LIGHT AND VARIABLE...MAINLY SOUTHWEST MONDAY...AS A SURFACE HIGH PRESSURE SYSTEM DOMINATES THE LOWER LEVELS. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z TUESDAY... FORECAST CONFIDENCE: MEDIUM. ALTERNATE SCENARIOS: TIMING AND LOCATION OF FOG OR LOW STRATUS...WILL VARY DEPENDING OF UPPER TO MID LEVEL CLOUDS. 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 MON 08/19/13 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 M H L L L L L L L L L HTS CONSISTENCY H M H L L L L L L L L L BKW CONSISTENCY M M M M H H H H H H H H EKN CONSISTENCY M L L L L L L L L H H M PKB CONSISTENCY M L L L L L L L L L L L CKB CONSISTENCY M M M H H H H M M H H H AFTER 00Z TUESDAY... AREAS OF IFR IN DENSE FOG MOST MORNINGS THIS WEEK...ESPECIALLY ALONG THE RIVERS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...ARJ/TRM/SL NEAR TERM...ARJ/TRM SHORT TERM...SL LONG TERM...JM AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
758 PM EDT SUN AUG 18 2013 .SYNOPSIS... SEVERAL WEAK WEATHER SYSTEMS WILL DRIFT SLOWLY THROUGH THE GREAT LAKES FROM TONIGHT THROUGH MID-WEEK...AS TEMPERATURES AND HUMIDITY CONTINUE TO SLOWLY INCREASE AT THE SAME TIME. NEITHER OF THE DISTURBANCES IS EXPECTED TO BRING MUCH COVERAGE OF RAIN...BUT THREATS FOR SHOWERS OR A FEW THUNDERSTORMS ON A LIMITED BASIS WILL BE PRESENT TONIGHT INTO MONDAY MAINLY EAST OF I-71...AND ON WEDNESDAY ESPECIALLY SOUTH OF I-70. IN BOTH CASES...MOST AREAS WILL STAY DRY...WITH MUGGY AND WARM AFTERNOONS AND MILD NIGHTS WITH LIGHT WINDS. ABOVE NORMAL TEMPERATURES WILL REMAIN ENTRENCHED THROUGH THE WEEK INTO NEXT WEEKEND...AS A VERY TYPICAL LATE SUMMER PATTERN REMAINS IN PLACE. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... A QUICK UPDATE EARLY THIS EVE TO CLEAN UP SKY/RAIN CHANCE IN ACCORDANCE WITH SATELLITE/RADAR TRENDS. PREVIOUS SCNTL OHIO RAIN AREA HAS FIZZLED QUICKLY SO LOWERED EARLY-MID EVENING RAIN CHANCES THERE. ALSO ACCOUNTED FOR POSSIBILITY THAT PULSEY/DISORGANIZED UPDRAFTS OVER CNTL KY MAY WANDER INTO OWEN/GRANT COUNTIES THROUGH 01Z. RECENT HRRR RUNS HAVE BACKED AWAY FROM ISOLD CONVECTION ALONG THE DIFFERENTIAL HEATING ZONE ON THE EDGE OF THE AFTN THICKER CLOUD SHIELD FROM OWEN/GRANT UP THROUGH CLINTON COUNTY...THOUGH LOW LEVEL MOISTURE IS POOLED HERE...WITH DWPT AT KILN AT 66F. CHCS FOR DIURNALLY TIED CONVECTION HAVE WANED CONSIDERABLY GIVEN SATELLITE TRENDS...SO RAIN CHANCES REDUCED HERE FOR THE EVENING. ALSO...BASED ON LATEST DATA...THE LATE EVE/OVERNIGHT RAIN CHANCES IN THE SCIOTO VALLEY AND UP TOWARD LICKING COUNTY MAY NEED TO BE PULLED ALTOGETHER. WILL MONITOR. PREVIOUS DISCUSSION FOLLOWS BELOW.... DISORGANIZED SHIELD OF VERY LIGHT RAIN/SPRINKLES HAS BEEN PUSHING STEADILY NORTHEAST THROUGH THE AFTERNOON UP THE SCIOTO RIVER VALLEY...IMMEDIATELY IN ADVANCE OF A MID-LEVEL VORTICITY MAX SEEN SWIRLING BOTH ON VISIBLE SATELLITE IMAGERY AND ON RADAR MOSAICS OVER NRN KENTUCKY. THIS IS NEAR THE NOSE OF A NARROW 250MB JETLET /115KT/ THAT IS SHIFTING NORTHEAST AND ALLOWING THE OPENING/SHEARING OF THE OLD CLOSED LOW THAT HAD BEEN SPINNING WELL SOUTHWEST OF THE AREA THE PAST FEW DAYS. THE MID/UPPER LEVEL SHORTWAVE TROUGH IS POSITIVELY TILTED...AND WEAKENING WITH TIME...WITH DECREASING LARGE SCALE ASCENT AND VERY WEAK SURFACE FEATURES UNDERNEATH. THE 18.18Z RAP HAD A NICE HANDLE ON THE MID LEVEL VORT MAX DRIVING NORTHEAST THROUGH SCNTL OH...AND CONTINUES TO LIFT THIS FEATURE OUT OF THE AREA THROUGH MID EVENING...WITH THE SHIELD OF LIGHT RAIN/SPRINKLES LIKELY EXITING THE AREA BY 00Z OR SO...IF IT DOESN/T FALL APART COMPLETELY BEFORE THEN. MESOANALYSIS CURRENTLY /19Z/ SHOWS A FAIRLY NICE DIFFERENTIAL HEATING ZONE /CAPE AXIS/ ON THE IMMEDIATE WEST SIDE OF THE RAIN SHIELD...RUNNING FROM OWEN/GRANT COUNTIES UP THROUGH THE WILMINGTON AREA TOWARDS CMH. VARIOUS AND SUNDRY CONVECTION ALLOWING MODEL RUNS /3-4KM RESOLUTION/ HAVE TRIED TO DEVELOP ISOLATED STORMS IN THIS CORRIDOR IN THE NEXT FEW HOURS UP THROUGH ABOUT 02Z...SO WE ARE IN NO HURRY TO DECREASE/SHRINK RAIN CHANCES WEST OR SOUTHWEST OF CURRENT RAIN SHIELD OVER SCNTL OH. WHILE MLCAPE IS LARGELY WEAK /300-700 J/KG/...THE PASSING OF THE MID/UPPER LEVEL PV ANOMALY ACROSS THIS AREA THROUGH THE NEXT FEW HOURS MAY AGITATE THE WEAK BAROCLINIC ZONE FOR A STORM OR TWO. LATER THIS EVENING/OVERNIGHT...ONE MORE SURGE /IF YOU CAN CALL IT THAT - IT IS QUITE WEAK/ OF MOISTURE ADVECTION RIDES FROM ERN TN/KY INTO CNTL/ERN OH AND MAY PROMOTE SOME -SHRA REGENERATION OVER THE SCIOTO VALLEY AND UP TOWARD/EAST OF CMH...SO WE HOLD ON TO HIGHER RAIN CHANCES HERE LATER THIS EVENING AND OVERNIGHT. NOT SURE IF THIS WILL LEAD TO MUCH ACTIVITY OR NOT...CONFIDENCE IS LOW...BUT THE SIGNAL HAS BEEN PRESENT FOR A FEW DAYS THUS DON/T WANT TO BACK AWAY YET. KEPT MIN TEMP FORECAST RIGHT WHERE IT WAS FOR THE MOST PART...WELL TRENDED IN THE LOWER 60S MOST AREAS...THOUGH MIXED OUT DEW POINTS IN WCNTL OHIO/ERN IND SUGGEST SOME MID TO UPPER 50S IN THAT AREA WHERE PRECIPITABLE WATER MINIMUM EXISTS. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... THE LAST WEAK SURGE OF MOISTURE MAY LINGER SHOWER CHANCES IN THE EAST IN THE MORNING...AND THERE MAY BE JUST ENOUGH DIURNAL INSTBY FOR A SHOWER/STORM IN THE FAR EAST/SOUTH IN THE AFTERNOON...BUT MONDAY IS LARGELY A DRY DAY FOR THE FORECAST AREA WITH INCREASING SUBSIDENCE IN THE WAKE OF THE DEPARTING SHORTWAVE TROUGH WHICH WILL BE SHEARING DOWNSTREAM THROUGH PA/NY. DESPITE ITS DEPARTURE...THERE REMAINS A WEAKNESS IN THE LARGER SCALE HEIGHT FIELD BETWEEN TWO LARGE ANTICYCLONES OFF THE SOUTHEAST CONUS AND OVER THE CNTL CONUS. THIS WEAKNESS IS A SOURCE OF LINGERING WEAK SHORTWAVE ENERGY...AND WITH THIS AXIS LINGERING IN THE FAR SOUTH/EAST...THUS THE SMALL RAIN CHANCES LINGERING UNTIL THAT AXIS CAN CLEAR IN THE MID AFTERNOON HOURS. MOST AREAS WILL SEE A FAIR AMOUNT OF SUNSHINE ON MONDAY...WITH TEMPS ADDING A FEW MORE DEGREES TO PUT MOST AREAS IN THE LOW-MID 80S. BRIEF SHORTWAVE RIDGING SLIDES IN FOR MONDAY NIGHT...WITH SKIES GOING CLEAR. THIS SHOULD ALLOW A LITTLE BETTER TEMP DROP WITH PWAT DROPPING OFF BACK TOWARD 1 INCH /BELOW SEASONAL NORMS/. THUS...SIDED WITH SOME OF THE MOS DATASETS THAT ALLOWED COOL SPOTS TO DROP OFF PRETTY DECENTLY MON NIGHT INTO THE UPPER 50S. WITH SUCH LIGHT WINDS OVER THE NEXT COUPLE NIGHTS...ALMOST CERTAIN TO BE COMMON SUMMER NIGHT FOG IN LOW LYING AREAS...BUT NOT SEEING A GREAT SIGNAL FOR SOMETHING WIDESPREAD TO INCLUDE IN THE FORECAST AS OF YET. && .LONG TERM /TUESDAY THROUGH SUNDAY/... SURFACE HIGH PRESSURE WILL ESTABLISH ITSELF TO OUR SE ON TUESDAY IN WAKE OF DEPARTING UPR LVL SYSTEM. WE SHOULD SEE A MOSTLY SUNNY TO PARTLY SUNNY DAY. MODELS HAD BEEN SUGGESTING THAT PERHAPS A POP OF SHOWER OR STORM COULD OCCUR IN THE FAR SOUTH DURING THE HEAT OF THE DAY. THIS STILL MAY OCCUR...BUT DO NOT FEEL IT WARRANTS A 20 POP MENTION SO HAVE ALLOW THE FORECAST TO REMAIN DRY. HIGHS WILL BE A LITTLE WARMER...GENERALLY IN THE MID 80S. FOR THE PERIOD TUESDAY NIGHT INTO WEDNESDAY NIGHT...MAJORITY OF MODELS HAVE COME MORE IN LINE ON WHAT WILL HAPPEN TO EMBEDDED S/WV ENERGY WITHIN THE NW FLOW ALOFT. IT APPEARS THIS ENERGY WILL DEVELOP INTO A CLOSED LOW TO OUR WEST...THEN WILL SLOWLY PROGRESS EAST THROUGH THE REGION WEDNESDAY INTO WEDNESDAY NIGHT. ECMWF/GFS SUGGEST THAT SOME EMBEDDED S/WV ENERGY MOVING NE AROUND DEVELOPING CLOSED LOW COULD SPARK A FEW SHOWERS AND THUNDERSTORMS BEGINNING ACRS OUR SW TUESDAY NIGHT. HAVE GIVEN ALL LOCATIONS AT LEAST A THREAT FOR SHOWERS AND STORMS ON WEDNESDAY WITH THE HIGHER CHANCES FAVORING THE SRN ZONES DUE TO HIGHER INSTABILITY AND MOISTURE. HAVE ALLOWED POPS TO FALL OFF OVERNIGHT WEDNESDAY NIGHT AS SYSTEM HEADS EAST. HIGHS ON WEDNESDAY WILL BE SLIGHTLY COOLER...ESPECIALLY SOUTHWEST CLOSER TO THE UPR LVL LOW. FOR THE PERIOD THURSDAY INTO FRIDAY NIGHT...MODELS CONTINUE TO STRUGGLE ON HOW LONG WAVE TROUGH ENERGY WILL DIG SE INTO SE CANADA AND NEW ENGLAND DURING THE PERIOD. AS SUCH...ASSOCIATED COLD FRONT AND WHERE IT WILL END UP...I.E. WILL IT PUSH THROUGH...STALL OUT OVER OUR AREA...OR PERHAPS FALL APART...IS STILL IN QUESTION. HAVE TAKEN A BLEND OF WPC AND THE LATEST 18.12Z ECMWF...WHICH ALLOWS THE FRONT TO APPROACH THE REGION FROM THE NORTH THURSDAY NIGHT...SLOW IT UP AS IT PUSHES INTO THE REMAINDER OF THE AREA ON FRIDAY...THEN WASHES IT OUT FRIDAY NIGHT INTO SATURDAY AS ANOTHER HIGH PRESSURE RIDGE BUILDS IN FROM THE NORTH. GIVEN LACK OF STRONG UPR SUPPORT...AS IT IS FCST TO REMAIN WELL OFF TO THE NE...ALONG WITH WEAK LOW LEVEL FORCING...HAVE KEPT POPS LOW THURSDAY NIGHT INTO FRIDAY. HAVE THEN ALLOWED CONDITIONS TO DRY OUT BY FRIDAY NIGHT. TEMPERATURES WILL BE CLOUD DEPENDENT BUT SHOULD SEE A SLIGHT BUMP UP AHEAD OF THE FRONT ON THURSDAY WITH SIMILAR OR SLIGHTLY COOLER CONDITIONS POSSIBLE ON FRIDAY. SURFACE HIGH PRESSURE WILL MOVE EAST THROUGH THE UPCOMING WEEKEND AS A MID LVL RIDGE BEGINS TO NUDGE INTO FROM THE CNTRL PLAINS. CONDITIONS SHOULD REMAIN DRY. TEMPERATURES WILL BE SEASONABLY WARM FOR LATE AUGUST. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... SHOWERS HAVE DISSIPATED ACROSS MUCH OF CENTRAL OHIO THIS EVENING. EARLY THIS EVENING AN AREA OF SCATTERED SHOWERS AND THUNDERSTORMS WAS MOVING NE TOWARD ILN/S NORTHERN KY COUNTIES...HOWEVER THIS CONVECTION SHOULD MISS ANY TAF SITES BEFORE DISSIPATING. THE CLOSED LOW THAT HAS BEEN SPINNING WELL SW OF THE AREA THE PAST FEW DAYS WILL CONTINUE TO OPEN AND SHEAR OVER THE NEXT 12 TO 18 HOURS. THE MID/UPPER LEVEL SHORTWAVE TROUGH IS POSITIVELY TILTED AND WEAKENING WITH TIME AS IT MOVES EAST...PROVIDING LESS SUPPORT FOR ANY SHOWERS/THUNDERSTORMS FOR THE REMAINDER OF THE TAF PERIOD. WHILE THERE IS A SLIGHT CHANCE OF SEEING A SHOWER IN THE EAST LATER TONIGHT...OPTED TO KEEP ALL TAFS DRY THROUGH THE FORECAST PERIOD. WITH THE LOSS OF DAYTIME HEATING...THE CU FIELD DIMINISHED. CLEARING AND LIGHT WINDS ARE EXPECTED AT TAF SITES OVERNIGHT AND THIS WILL BRING THE POSSIBILITY OF MVFR VSBYS IN FOG FROM 19/09Z TO 19/13Z. KLUK AND KILN MAY DEVELOP IFR VSBYS IN FOG BUT NOT CONFIDENT ENOUGH TO INCLUDE IN FORECAST AT THIS TIME. VFR CONDITIONS EXPECTED AFTER 19/13Z WITH SCATTERED CU DEVELOPING. OUTLOOK...NO SIGNIFICANT WEATHER EXPECTED. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...BINAU NEAR TERM...BINAU SHORT TERM...BINAU LONG TERM...HICKMAN AVIATION...PARKER
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
1140 PM EDT SUN AUG 18 2013 .SYNOPSIS... A WEAK DISTURBANCE WILL PASS ACROSS PA ON MONDAY...BRINGING CLOUDS AND SOME RAIN. HIGH PRESSURE CENTERED NEAR BERMUDA WILL CONTROL THE WEATHER ACROSS PA DURING MIDWEEK...DELIVERING WARMER AND MORE HUMID CONDITIONS BEFORE A COLD FRONT ARRIVES AROUND FRIDAY. && .NEAR TERM /UNTIL 8 AM MONDAY MORNING/... VERY LIGHT RAIN OVER WRN PA IS JUST NOT HOLDING TOGETHER DUE TO LACK OF SFC FEATURE TO CONCENTRATE/FOCUS LIFT. WIDESPREAD LIFT ALOFT WILL CONTINUE TO MAKE SOME LIGHT RAIN AND IT SHOULD SPREAD SLOWLY TO THE EAST AS THE UPPER TROUGH OPENS UP AND SLIDES EAST. && .SHORT TERM /8 AM MONDAY MORNING THROUGH 6 PM MONDAY/... SLOW MOVING UPPER TROF WILL TAP 1.5" PW FOR MORE WIDESPREAD CHC OF SHOWERS AND TSTORMS ACROSS MOST AREAS ON MONDAY. INCREASED POPS SUBSTANTIALLY FOR THE DAYTIME HOURS...DESPITE ONLY WEAK BOUNDARY LAYER FORCING. GIVEN CLOUD COVER...CAPES WILL BE LIMITED... SO SEVERE WEATHER IS NOT EXPECTED. HIGHS WILL BE MILDER THAN TODAY WITH TEMPS REACHING THE MID 70S NORTH TO THE LOWER 80S SOUTH. && .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... INTERESTING LOW OFF NORFOLK VA THIS AFT...STARTING TO PULL AREA OF SHOWERS EAST OF THE AREA THIS AFT...BUT MORE SHOWERS ACROSS THE OH VLY WITH THE UPPER LVL LOW. EXPECT SHOWERS TO LINGER INTO MONDAY...BEFORE CONDITIONS IMPROVE LATE. AFTER THIS...MAINLY DRY EXPECT FOR LATER THU INTO FRIDAY... WHEN A COLD FRONT MOVES ACROSS PA. SOME RISK OF SHOWERS ON WED ACROSS THE SE LIKE TODAY...BUT LEFT OUT FOR NOW. OVERALL A COMPLEX PATTERN...WITH THE TENDENCY FOR MORE STABLE AND LESS HUMID AIR TO TRY TO BUILD SOUTHWARD EAST OF THE MOUNTAINS... GIVEN HIGH OVER EASTERN CANADA AND NEW ENGLAND THIS WEEK. AT THE SAME TIME...WARMER AND MORE HUMID AIR WORKS NORTHWARD WEST OF THE MOUNTAINS. FOR NOW...LEFT MAX TEMPS CLOSE TO WHAT WAS IN THE GRIDS. REAL STRONG WARM ADVECTION WITH STRONG WESTERLY FLOW WILL BE WELL NORTH OF THE US...CANADIAN BORDER FROM LATE TUE INTO EARLY THU. MAIN CHANGE WAS TO UP MIN TEMPS MONDAY NIGHT AND TUE NIGHT...GIVEN GUIDANCE AND OTHER OFFICES. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... VERY SUBTLE FEATURES DRIVING THE FORECAST FOR THE NEXT 24 HOURS...AND THEREFORE FORECAST IS OF SOMEWHAT LOWER CONFIDENCE. VERY LITTLE PRECIPITATION REMAINS ON RADAR...AS WESTERN PA ACTIVITY HAS DWINDLED TO JUST A FEW SCATTERED SHOWERS. SHORT RANGE MODELS CONTINUE TO SUPPORT THE IDEA OF SHOWERS REDEVELOPING OVERNIGHT ACROSS THE WEST...AND SPREADING INTO CENTRAL PA BY MORNING. RUC ALSO CONTINUES THE THINKING OF DEVELOPING SCATTERED CONVECTION ACROSS CENTRAL AREAS TOMORROW AFTERNOON...PROPAGATING TO THE SOUTH AND EAST. HOWEVER...BASED ON RADAR TRENDS...HAVE CUT BACK ON PRECIPITATION IN MOST TAFS OVERNIGHT. FOG AND LOWER STRATUS FORECAST BY MODELS ALSO SLOWER THAN EXPECTED IN PREVIOUS FORECAST...WITH ALL LOCATIONS AT 03Z STILL VFR. WILL CONTINUE THE THINKING ALONG THE LINES OF LOWER CLOUDS AND FOG FORMATION...BUT HAVE BACKED OFF A BIT ON LOWER LIMITS OF RESTRICTIONS. UPPER TROF AXIS LIFTS NORTHEAST MONDAY. RESULT WILL BE SLIGHT SURFACE RIDGING DEVELOPING DURING THE DAY AND A SUBTLE/GRADUAL WIND SHIFT TO THE WEST DURING THE AFTERNOON. HOWEVER...REMNANTS OF UPPER TROF MOVING THROUGH THE REGION COULD DEVELOP SOME CONVECTION. WITHOUT A REAL PUSH OF DRIER AIR...EXPECT MORE FOG FORMATION MONDAY NIGHT INTO TUESDAY...BEFORE A RETURN TO VFR BY MID WEEK. OUTLOOK... MON...AM MVFR/IFR...WITH IMPROVEMENTS DURING THE AFTERNOON MOST LOCATIONS. ADDITIONALLY...SCATTERED SHOWERS AND ISOLATED TSRA. TUE...AM FOG POSS. THEN MAINLY VFR. WED-THU...VFR. FRI...MVFR WITH SCT SHRA/TSRA. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DEVOIR NEAR TERM...DANGELO SHORT TERM...DEVOIR LONG TERM...MARTIN AVIATION...JUNG
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1237 PM CDT SAT AUG 17 2013 .UPDATE...FOR 18Z AVIATION. && .AVIATION...18Z TAF DISCUSSION. A WEAK INVERTED TROUGH IS PROVIDING DECENT LOW LEVEL MOISTURE TRANSPORT INTO THE STATE TODAY. THIS MEANS MOSTLY CLOUDY SKIES WILL CONTINUE FOR MOST OF...IF NOT ALL...OF THIS PERIOD. IN ADDITION...THERE SHOULD BE JUST ENOUGH HEATING TO HELP SPARK A FEW SHOWERS THIS AFTERNOON. THE MAJORITY OF THIS ACTIVITY SHOULD REMAIN ALONG AND WEST OF INTERSTATE 65 AS AN UPPER LEVEL LOW CENTERED OVER THE MISSISSIPPI RIVER WILL BE THE PROVIDER OF THE LIFT. LATER TONIGHT...WIDESPREAD SHOWERS ARE EXPECTED TO START MOVING INTO THE EASTERN HALF OF THE STATE FROM THE SOUTHEAST. WILL GO AHEAD AND PREVAIL NOT ONLY THIS RAIN...BUT ASSOCIATED FLIGHT CATEGORY DEGRADATION STARTING BY 03Z THIS EVENING AT KCSV. KCKV/KBNA WILL ALSO SEE REDUCED FLIGHT CATEGORIES...WITH SOME LIFR POSSIBLE AROUND DAYBREAK AT KCKV. WINDS WILL REMAIN LIGHT...MAINLY OUT OF THE SOUTHEAST. UNGER && .PREV DISCUSSION... /ISSUED 905 AM CDT SAT AUG 17 2013/ UPDATE... EARLIER SHOWER AND TSTM ACTIVITY HAS LIFTED OFF TO THE NORTH. A BAND OF VERY LIGHT SHOWER ACTIVITY APPEARS TO BE WORKING NORTHWARD ACROSS CENTRAL AREAS. OVERALL HOWEVER...MODELS ARE ZONING IN ON A PERIOD OF SUBSIDENCE THROUGH THE MORNING HOURS. HOWEVER...BY AFTERNOON SUBSIDENCE WILL BEGIN TO GIVE WAY TO A SLIGHTLY UPWARD OMEGA FIELD AND THUS...SHOULD STILL SEE CONVECTIVE ACTIVITY INCREASE. HRRR IN SUPPORT OF REDEVELOPMENT AS WELL. FOR THE GRID UPDATE...WILL TWEAK POPS DOWN FOR THE PRE 18Z PERIOD. OTW...LITTLE ADJUSTMENTS NEEDED. MOSTLY CLOUDY SKIES SHOULD PREVAIL AND THUS THE EXPECTED HIGH TEMPS IN THE LOWER 80S STILL LOOKS REASONABLE. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 27
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
905 AM CDT SAT AUG 17 2013 .UPDATE... EARLIER SHOWER AND TSTM ACTIVITY HAS LIFTED OFF TO THE NORTH. A BAND OF VERY LIGHT SHOWER ACTIVITY APPEARS TO BE WORKING NORTHWARD ACROSS CENTRAL AREAS. OVERALL HOWEVER...MODELS ARE ZONING IN ON A PERIOD OF SUBSIDENCE THROUGH THE MORNING HOURS. HOWEVER...BY AFTERNOON SUBSIDENCE WILL BEGIN TO GIVE WAY TO A SLIGHTLY UPWARD OMEGA FIELD AND THUS...SHOULD STILL SEE CONVECTIVE ACTIVITY INCREASE. HRRR IN SUPPORT OF REDEVELOPMENT AS WELL. FOR THE GRID UPDATE...WILL TWEAK POPS DOWN FOR THE PRE 18Z PERIOD. OTW...LITTLE ADJUSTMENTS NEEDED. MOSTLY CLOUDY SKIES SHOULD PREVAIL AND THUS THE EXPECTED HIGH TEMPS IN THE LOWER 80S STILL LOOKS REASONABLE. && .PREV DISCUSSION... /ISSUED 649 AM CDT SAT AUG 17 2013/ UPDATE...FOR 12Z AVIATION FORECASTS. AVIATION...CKV AND BNA RECEIVED LOCALLY HEAVY RAINFALL LAST NIGHT AND MAY SEE A BRIEF PERIOD OF SOME RAG TAG IFR OR MVFR CIGS EARLY THIS MORNING. OTHERWISE, EXPECT VFR CIGS THROUGHOUT THE TAF PERIOD. SOME BRIEF VIS RESTRICTIONS ARE LIKELY WITH ANY SHRA OR ISOLATED TSRA THAT MIGHT PASS OVER A MID STATE TERMINAL. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 21
AREA FORECAST DISCUSSION
NWS MIDLAND/ODESSA TX
1222 AM CDT Sat Aug 17 2013 .DISCUSSION... See Aviation Discussion below. && .AVIATION... VFR conditions will prevail next 24 hours. Latest radar loop shows convection N of KHOB diminishing, and remnants look to pass NE of the terminal. Otherwise, another widespread CU field is expected to develop today 16-19Z, w/bases 7-8 kft agl. && .PREV DISCUSSION... /ISSUED 633 PM CDT Fri Aug 16 2013/ AVIATION... 00Z TAF issuance... No major aviation concerns for the next 24...VFR conditions are expected at all TAF sites. There is currently come thunderstorm activity just west of CNM this evening but NM terminals do not look to be affected in the immediate future. Will need to keep an eye on any convection moving south out of Chaves county and send an update to include mention of TSRA if needed. Generally light east southeasterly winds this evening should persist overnight and into Saturday. PREV DISCUSSION... /ISSUED 154 PM CDT Fri Aug 16 2013/ DISCUSSION... The Mesoscale Convective Complex which clipped the western Low Rolling Plains this morning generated quite the bubble surface high and sent an outflow boundary westward across the CWA. The modified airmass behind this boundary will result in high temperatures several degrees lower than what was previously expected, especially over the eastern half of the forecast area, and will affect convection this afternoon, and more than likely, tonight. The latest RUC bears this out with a higher theta e axis at H7 shunted west of the 16/12Z operational models. Think we will still see widely scattered thunderstorms over the higher terrain through max heating, but think convection will drop into southeast New Mexico along the theta e axis overnight. Instability around 1000 J/Kg, mid level lapse rates of 7.5-8 C/Km and 0-6 Km Bulk Shear Vectors around 35kt could yield a few strong to severe storms. Since the overall threat is limited, will make a mention in the HWO. Think convection Saturday and Sunday will mainly occur over the higher terrain as an upper ridge over Arizona repositions further north over the Four Corners region, with the flow aloft over the CWA becoming more northeasterly. Storms will likely develop over the higher terrain of New Mexico each afternoon, then spread south/ southwestward under the eastern fringe of the upper ridge. Temperatures will stay near to above normal through the weekend. Models are still undecided on whether an inverted upper trough will trek westward into the area from the Gulf of Mexico next week. Will not add any rain chances at this time, but some could be added mid to late next week for such a feature if the upper ridge does not remain too strong for it to impinge upon the area. Temperatures should be near normal next week, especially the second half. && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ 44
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1140 PM CDT FRI AUG 16 2013 .DISCUSSION... See aviation discussion below. && .AVIATION... VFR will prevail the next 24 hours with light winds through the period. && .PREV DISCUSSION... /ISSUED 723 PM CDT FRI AUG 16 2013/ DISCUSSION... Expect VFR conditions to prevail over west central Texas through the next 24 hours. AVIATION... Early morning convection has stabilized the atmosphere today. Soundings do hint at the possibility of FEW150 during the overnight hours, but given the lack of any evidence of this upstream on satellite imagery, will opt to maintain SKC at all terminals. Winds are expected to become light and variable overnight. PREV DISCUSSION... /ISSUED 336 PM CDT FRI AUG 16 2013/ SHORT TERM... /Tonight and Tomorrow/ Visible satellite imagery shows sunny skies across West Central Texas this afternoon. The latest mesoanalysis indicates a stable environment over our area, with an instability axis across South and far West Texas. The models, including the 3KM HRRR model develop scattered thunderstorms over Eastern New Mexico and far West Texas in the instability axis during the late afternoon and evening. Upper level northerly flow will keep this activity west of our area for tonight. Lows will be in the mid 60s to lower 70s. Going with a dry forecast for Saturday across the area. Isolated thunderstorms will probably fire to our west during the afternoon hours. The upper level northerly flow should keep the storms west of our area. Highs will be in the lower to mid 90s. LONG TERM... /Saturday Night through Friday/ The upper level flow will be north to northeast next week as a high pressure ridge sets up from the Southern Rockies into the Central Plains. Basically a normal summertime pattern with little upper level and mesoscale forcing. Temperatures will be near or slightly above seasonable normals. Highs will be in the 90s with lows in the upper 60s to lower 70s. Going with a dry forecast through the extended period. && .PRELIMINARY POINT TEMPS/POPS... Abilene 66 92 67 94 68 / 10 10 5 5 5 San Angelo 67 93 68 95 68 / 10 10 5 5 5 Junction 68 94 69 97 66 / 10 10 5 5 5 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 24
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
247 PM EDT SAT AUG 17 2013 .SYNOPSIS... A RIDGE OF HIGH PRESSURE WILL REMAIN SITUATED ALONG THE LEE OF THE CENTRAL APPALACHIANS. AN AREA OF LOW PRESSURE WILL PROGRESS NORTHEAST ALONG THE STALLED FRONTAL BOUNDARY THAT EXTENDED FROM GEORGIA TO THE COAST OF THE CAROLINAS. AN ACTIVE WEATHER PATTERN WILL CONTINUE INTO THE EARLY PART OF NEXT WEEK AS A TROUGH OF LOW PRESSURE APPROACHES THE REGION FROM THE WEST. && .NEAR TERM /THROUGH SUNDAY/... AS OF 230 PM EDT SATURDAY... EARLY THIS AFTERNOON...AREAS OF RAIN WERE EXPANDING IN COVERAGE IN RESPONSE TO THE NEXT UPPER LEVEL WAVE APPROACHING IN THE UPPER LEVEL SOUTHWEST FLOW. MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT THAT ISENTROPIC LIFT ON THE 305K SFC SIGNIFICANTLY INCREASES BETWEEN NOW AND EARLY TONIGHT. AS A RESULT...HAVE RAMPED UP POPS THROUGH THE EVENING HOURS...WITH PRECIPITATION ARRIVING LAST IN THE GREENBRIER VALLEY. WITH ABUNDANT CLOUDS AND WIDESPREAD PRECIP...EXPECT A SMALL DROP IN TEMPS TONIGHT AND GENERALLY WENT ABV GUIDANCE FOR LOWS. ON SUNDAY...WE BEGIN TO BECOME UNDER THE INFLUENCE OF THE WEAKENING UPPER LEVEL WAVE IN THE OHIO VALLEY. THE 850-700MB FLOW VEERS TO THE WEST WHICH REDUCES THE MOISTURE DEPTH. HOWEVER...WITH A SHALLOW WEDGE STILL EXPECTED TO BE IN PLACE...AREAS OF DRIZZLE/LIGHT RAIN WILL CONTINUE SUNDAY. A FEW BREAKS IN THE CLOUDS MAY BE SEEN IN THE FAR SOUTHWEST AND THE FAR SOUTHERN PORTION OF THE FORECAST AREA...BUT ONLY A SMALL RISE IN TEMPS IS ANTICIPATED AND WENT BELOW GUIDANCE AT MOST LOCATIONS FOR HIGHS SUNDAY. FORECAST HIGHS ARE A FEW DEGREES ABOVE THE RECORD MINIMUM HIGH TEMPS FOR AUGUST 18TH (SEE CLIMATE SECTION) && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... AS OF 230 PM EDT SATURDAY... THE UPPER TROUGH THAT HAS BEEN LINGERING OVER THE MID-MISSISSIPPI VALLEY WILL MAKE GRADUAL PROGRESSION EASTWARD DURING THIS PART OF THE FORECAST. AS IT DOES...THE FLOW AND THE AIRMASS IN ADVANCE OF IT WILL HAVE PLENTIFUL GULF OF MEXICO MOISTURE AND LINGERING OUTFLOW BOUNDARIES FROM PRIOR CONVECTION. THE RESULT IS EXPECTED TO BE SCATTERED SHOWERS AND A FEW THUNDERSTORMS THROUGH AT LEAST MONDAY. ON TUESDAY...WE WILL NOT HAVE A DRY FORECAST...BUT ONE THAT IS STARTING TO TREND TOWARDS LESS COVERAGE OF SHOWERS AND STORMS. A WEAKENING OF THE UPPER TROUGH AND TRANSITION TO A MORE ZONAL FLOW IS TO BLAME. TEMPERATURES WILL ALSO START TO MODERATE A BIT DURING THIS TIME PERIOD. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... AS OF 1245 PM EDT SATURDAY... DURING THIS PORTION OF THE FORECAST...MODEL GUIDANCE TRANSITIONS FROM A NEAR ZONAL FLOW ACROSS THE AREA...TO ONE THAT HAS SOME DEGREE OF A NORTHWEST FLOW ORIENTATION. THIS COMES WITH DIFFERENCES IN THE POSITION OF A BUILDING UPPER HIGH/RIDGE. THE GFS SOLUTION IS FARTHER WEST WITH THE HIGH...KS/MO...AND AS SUCH HAS A STEEPER ANGLE OF THE NORTHWEST FLOW OVER THE REGION...AND A BETTER SHOT FOR UPSTREAM DISTURBANCES TO HEAD INTO OR NEAR THE REGION. THE ECWMF OFFERS A SOLUTION WITH THE CENTER OF THE UPPER HIGH OVER THE LOWER OHIO VALLEY...WITH STEEPER NORTHWEST FLOW ON ITS EASTERN SIDE MORE OVER NY/PA THAN OVER OUR REGION. THE OPERATIONAL GFS SOLUTION OFFERS A COOLER AND POTENTIALLY WETTER SOLUTION AS COMPARED TO THE OPERATIONAL ECMWF. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... AS OF 120 PM EDT SATURDAY... RATHER CHAOTIC PATTERN IN THE SHORT TERM. SHALLOW WEDGE IN PLACE ALONG THE ERN SEABOARD AS PIECES OF ENERGY MOVE OVER THE AREA IN SWLY FLOW AHEAD OF CLOSED LOW OVER THE MID MISSISSIPPI VALLEY. MODEL PCPN FIELDS HAVE BEEN OVERDONE WITH THIS SYSTEM AND CURRENTLY ONLY SEEING PATCHY LIGHT PCPN NEAR KDAN. WITH SUCH A DIFFUSE PATTERN WILL NOT TRY TO GET FANCY WITH TIMING OF ELEMENTS BUT LIKING THE LATEST GFS AND HRRR RUNS FOR OVERALL TRENDS. EXPECTING PCPN TO BE ON THE INCREASE FROM THE SOUTHWEST...MAINLY FROM 00Z ON THOUGH IT LOOKS TO TAKE A BIT LONGER TO WORK INTO KLWB. AS PCPN GETS GOING CIGS AND VSBYS WILL BE COMING DOWN OVERNIGHT. EXPECTING IFR TO DEVELOP AFTER ABOUT 06ZAT ALL LOCATIONS...BUT MAINLY DUE TO CIGS AT KDAN...KLYH...AND KROA. LOOKS LIKE PCPN WILL BE TAPERING OFF TOWARD 12Z AS SFC LOW ALONG THE COAST STARTS TO PULL OFF TO THE NORTHEAST. NOT EXPECTING SIGNIFICANT WINDS THROUGH THE TAF PERIOD. AVIATION EXTENDED... WEATHER WILL REMAIN UNSETTLED THROUGH THE START OF NEXT WEEK AS AFOREMENTIONED CLOSED LOW OPENS UP AND LIFTS OUT...ALLOWING FOR SOME FLAT RIDGING BY MIDWEEK. HOWEVER...EASTERN TROF WANTS TO REDEVELOP TOWARD THE END OF THE WEEK WHICH BRINGS UNSETTLED CONDITIONS BACK TO THE AREA. EXPECT SOME LOW CIGS/VSBYS WITH NOCTURNAL FOG AND SOME DIURNAL CONVECTIVE PCPN THROUGH THE PERIOD...WITH TUESDAY AND WEDNESDAY LOOKING MOST FAVORABLE FOR AVIATORS. && .CLIMATE... AS OF 240 PM EDT SATURDAY... RECORD MINIMUM HIGH TEMPERATURES FOR AUGUST 18. CITY........RECORD/YEAR BLUEFIELD WV....70/1981 DANVILLE VA.....70/1992 LYNCHBURG VA....65/1957 BLACKSBURG VA...69/1992 ROANOKE VA......65/1957 && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...DS NEAR TERM...PH SHORT TERM...DS LONG TERM...DS AVIATION...MBS CLIMATE...PH
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
125 PM EDT SAT AUG 17 2013 .SYNOPSIS... HIGH PRESSURE ALONG THE MID ATLANTIC COAST WILL REMAIN WEDGED ALONG THE EASTERN SLOPES OF THE APPALACHIANS THROUGH THIS EVENING...MAINTAINING AN EASTERLY WIND ACROSS THE AREA. SEVERAL DISTURBANCES PASSING ALONG A STALLED FRONTAL BOUNDARY TO OUR SOUTH AND EAST WILL BRING PERIODS OF RAIN TO THE AREA THROUGH THE WEEKEND. SCATTERED SHOWERS MAY PERSIST EARLY NEXT WEEK AS A TROUGH OF LOW PRESSURE MOVES EASTWARD FROM THE OHIO VALLEY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 935 AM EDT SATURDAY... DRY AIR CONTINUES TO HOLD IN PLACE...ESPECIALLY ACROSS THE MOUNTAINS WITH DEWPOINTS STILL IN THE LOW TO MID 50S. THE 12Z RNK SOUNDING INDICATED A LARGE AREA OF DRY AIR...ESPECIALLY BELOW 700MB. IN THE UPPER LEVELS OF THE ATMOSHPERE...WATER VAPOR SATELLITE IMAGERY HINTS AT A WEAK WAVE EMBEDDED EMBEDDED IN THE SOUTHWEST FLOW MOVING ACROSS EASTERN NC HELPING TO GENERATE LIGHT RAIN SOUTH OF LYH INTO THE VA SOUTHSIDE AND NORTHERN NC PIEDMONT. THE BLENDED TOTAL PRECIP WATER IMAGE SHOWS HIGHEST PWAT AIR REMAINS IN THE FAR SOUTHEAST PORTION OF THE FORECAST AREA THIS MORNING. AS THE WEAK WAVE IN NC DRIFTS NORTHEAST THIS AFTERNOON...LIGHT PRECIP OCCURRING THIS MORNING SHOULD WANE BY MIDDAY. SHOWERS MAY RE-DEVEVLOP EARLY THIS AFTERNOON UNDER AXIS OF HIGHER PWAT AIR IN THE EAST...BUT FOR THE MOUNTAINS...PRECIP MAY NOT ARRIVE UNTIL THIS EVENING/TONIGHT WHEN THE NEXT UPPER LEVEL SHORTWAVE APPROACHES FROM THE SOUTHWEST. AS A RESULT...PUSHED UP HIGH TEMPS IN THE MOUNTAINS WHERE CLOUDS WILL BE SLOWER TO ARRIVE AND DELAYED THE ARRIVAL OF PRECIP. IN THE EAST...LITTLE CHANGES WERE MADE TO THE FORECAST...BUT DID INCREASE HIGHS AT LYH WHERE READINGS ARE ALREADY A FEW DEGREES ABV THE FORECAST. SHOULD BE UNDER DEEPER MOISTURE TONIGHT WITH A COMBO OF THE UPPER SYSTEM HEADING INTO THE WEST AND BETTER ONSHORE FLOW OUT EAST WITH THE SURFACE WAVE. ALSO BETTER DIFFLUENCE ALOFT AHEAD OF A SPEED MAX PASSING PASSING JUST WEST SHOULD COINCIDE WITH THE LINGERING THETA-E GRADIENT TO SUPPORT MORE WIDESPREAD -RA AND PERHAPS SOME ELEVATED HEAVIER SHRA OVER THE COOL POOL. THUS MOSTLY LIKELY/CAT POPS OVERALL. ONLY SMALL DIURNAL TEMP CHANGES UNDER THE CLOUD CANOPY/-RA WITH LOWS UPPER 50S/LOW 60S. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 332 AM EDT SATURDAY... AN UPPER LEVEL BLOCKING RIDGE IN THE WESTERN ATLANTIC IS EXPECTED TO JOG TO THE SOUTHWEST ON SUNDAY. THIS WILL ALLOW A COASTAL LOW TO TRACK NORTHEAST ALONG THE MID ATLANTIC COAST. MOISTURE ACROSS THE REGION SHOULD BECOME SHALLOWER AS THE FOCUS WILL BE WITH THE DEPARTING SURFACE LOW. DESPITE THE REDUCTION IN MOISTURE...GRAY/DAMP CONDITIONS WILL REMAIN AS THE SURFACE WEDGE WILL STILL BE IN PLACE SUNDAY MORNING. WITH THE BLOCKING HIGH JOGGING TO THE SOUTHWEST...THE CLOSED LOW OVER THE MID MISSISSIPPI VALLEY WILL OPEN INTO A TROUGH WHILE TRACKING TO THE OHIO VALLEY SUNDAY. PRESSURE FALLS OVER THE OHIO VALLEY AND WARM AIR ADVECTION FROM THE SOUTHWEST WILL ERODE THE WEDGE THROUGH THE DAY SUNDAY. RAIN AND DRIZZLE WILL THEN GET REPLACED BY SCATTERED SHOWERS AS THE UPPER LEVEL TROUGH AND ASSOCIATED SHORT WAVES APPROACH THE REGION SUNDAY AFTERNOON AND CROSS OVER THE AREA SUNDAY NIGHT. THE TROUGH AXIS IS OVERHEAD ON MONDAY TO KEEP SCATTERED SHOWERS AND THUNDERSTORMS IN THE FORECAST...BUT THE FOCUS OF AREAL COVERAGE WILL BE ALONG THE COAST. AS WITH ALL ERODING WEDGES...TEMPERATURES WILL BE TRICKY TO FORECAST. AREAS BREAKING OUT OF THE WEDGE SHOULD SEE TEMPERATURES JUMP INTO THE MID TO UPPER 70S DURING THE AFTERNOON. AREAS REMAINING IN THE WEDGE MAY STAY IN THE 60S. LOOKING AT THE LIFTED INDEX AND LOW LEVEL FLOW...THE NAM KEEPS THE WEDGE OVER RNK NORTHEAST CORNER DEEP INTO SUNDAY NIGHT. THE GFS HAS THE WEDGE CLEARING THE PIEDMONT SOMETIME SUNDAY EVENING. IF THIS IS THE CASE...THE CITY OF LYNCHBURG AND THE CENTRAL PIEDMONT OF VIRGINIA MAY AGAIN HAVE TEMPERATURES 20F COOLER THAN NORMAL. THE WEDGE WILL BE GONE MONDAY AND TEMPERATURES WILL APPROACH NORMAL BY THE AFTERNOON. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 330 PM EDT FRIDAY... A GENERAL WEAKNESS...IN AN OTHERWISE STAGNANT...UPPER LEVEL FLOW WILL COVER THE EASTERN U.S. THROUGH MOST OF THE LONG TERM PERIOD. THE 00Z ECMWF AND CANADIAN MODELS DEPICT AN UPPER LEVEL LOW ACROSS THE OHIO VALLEY...THEN DRIFTING SOUTHEAST THROUGH THE PERIOD. THE 12Z GFS IS NOW COMING AROUND TO THIS SOLUTION WHICH WOULD RESULT IN A MORE UNSETTLED PERIOD. WITH PWATS FORECAST TO REMAIN AROUND 1.5 INCHES AND WEAK LOW LEVEL SOUTH OR SOUTHEAST FLOW IN PLACE...WOULD EXPECT A TYPICAL SUMMER PATTERN OF DAILY (MAINLY DIURNALLY DRIVEN) SHOWERS AND STORMS DRIVEN BY LOCALIZED AREAS OF LOW LEVEL CONVERGENCE EACH DAY. TEMPERATURES THROUGH THE PERIOD SHOULD BE NEAR NORMAL TO SLIGHTLY ABOVE NORMAL...ESPECIALLY LATE IN THE PERIOD WITH GEFS SHOWS 850MB TEMPS RISING 1-2 STANDARD DEVIATIONS ABV NORMAL. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 120 PM EDT SATURDAY... RATHER CHAOTIC PATTERN IN THE SHORT TERM. SHALLOW WEDGE IN PLACE ALONG THE ERN SEABOARD AS PIECES OF ENERGY MOVE OEVR THE AREA IN SWLY FLOW AHEAD OF CLOSED LOW OVER THE MID MISSISSIPPI VALLEY. MODEL PCPN FIELDS HAVE BEEN OVERDONE WITH THIS SYSTEM AND CURRENTLY ONLY SEEING PATCHY LIGHT PCPN NEAR KDAN. WITH SUCH A DIFFUSE PATTERN WILL NOT TRY TO GET FANCY WITH TIMING OF ELEMENTS BUT LIKING THE LATEST GFS AND HRRR RUNS FOR OVERALL TRENDS. EXPECTING PCPN TO BE ON THE INCREASE FROM THE SOUTHWEST...MAINLY FROM 00Z ON THOUGH IT LOOKS TO TAKE A BIT LONGER TO WORK INTO KLWB. AS PCPN GETS GOING CIGSAND VSBYS WILL BE COMING DOWN OVERNIGHT. EXPECTING IFR TO DEVELOP AFTER ABOUT 06ZAT ALL LOCATIONS...BUT MAINLY DUE TO CIGS AT KDAN...KLYH...AND KROA. LOOKS LIKE PCPN WILL BE TAPERING OFF TOWARD 12Z AS SFC LOW ALONG THE COAST STARTS TO PULL OFF TO THE NORTHEAST. NOT EXPECTING SIGNIFICANT WINDS THROUGH THE TAF PERIOD. ...AVIATION EXTENDED... WEATHER WILL REMAIN UNSETTLED THROUGH THE START OF NEXT WEEK AS AFOREMENTIONEDCLOSED LOW OPENS UP AND LIFTS OUT...ALLOWING FOR SOME FLAT RIDGING BY MIDWEEK. HOWEVER...EASTERN TROF WANTS TO REDEVELOP TOWARD THE END OF THE WEEK WHICH BRINGS UNSETTLED CONDITIONS BACK TO THE AREA. EXPECT SOME LOW CIGS/VSBYS WITH NOCTURNAL FOG AND SOME DIURNAL CONVECTIVE PCPN THROUGH THE PERIOD...WITH TUESDAY AND WEDNESDAY LOOKING MOST FAVORABLE FOR AVIATORS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...JH/NF NEAR TERM...JH/PH SHORT TERM...RCS LONG TERM...PH AVIATION...MBS
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1202 AM EDT SAT AUG 17 2013 .SYNOPSIS... LOW PRESSURE WILL SLOWLY MOVE NORTHEAST ALONG THE MID ATLANTIC COAST THIS WEEKEND. HIGH PRESSURE RETURNS EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... WILL BE MAKING SIGNIFICANT CHANGES TO THE GRIDS THROUGH 00Z SUN WITH THE 1 AM UPDATE. MAIN CHANGE WILL TO LWR RAIN CHANCES ACROSS THE NRN HALF OF FA AND LIMITING IT TO SAT AFTRN. IT MAY NOT RAIN AT ALL ACROSS THE LW MD ERN SHORE UNTIL SAT EVE. RAIN CHANCES SLOWLY INCRS THROUGH THE DAY ACROSS THE SOUTH. THIS ALL BASED ON LATEST DATA WHERE THE MODELS ARE SHOWING DRYER AIR FROM THE HIGH PRS OVR THE AREA WINNING OUT ACROSS THE FA THRU AT LEAST 18Z. PVS DSCN: UPDATE AS OF 1045 PM EDT...ANOTHER STRANGE EVENING WHERE WX HAS BEEN TRENDING DRIER THAN EXPECTED. A BAND OF CLOUDS IS CURRENTLY MOVING OFF THE COAST AND A BATCH OF RAIN HAS DEVELOPED OVER THE VA TIDEWATER AND NE NC. WILL CONTINUE TO CARRY LIKELY POPS IN THIS AREA THRU EARLY AM AS PCPN EXITS. ELSEWHERE...CLEARING HAS WORKED INTO CENTRAL VA AND WILL CONTINUE TO ADVANCE EAST THRU EARLY AM. THIS CLEARING HAS ALLOWED TEMPS TO FALL A LITTLE LOWER THAN EXPECTED AND THUS HAVE LOWERED OVN LOWS A FEW DEGREES. LOWS IN THE UPR 50S NW TO THE MID 60S SE. THERE IS SOME INDICATION IN THE LATEST IR SATELLITE IMAGERY AND SFC OBS THAT CLOUDS MOVING NORTHWARD THRU CENTRAL NC WILL SPREAD OVER OUR AREA DURING THE PRE-DAWN HOURS SO WILL HAVE CLOUDS RETURNING OVERNIGHT. HOWEVER..QUESTIONS REMAIN AS TO JUST HOW MUCH PCPN WILL PUSH NORTHWARD BY DAYBREAK. LATEST NAM AND HRRR ARE NOT THAT EXCITED ABOUT RAIN GETTING NORTH OF THE HWY 58 IN SOUTHERN VA TIL AFTER 15Z SAT...SO NEXT SHIFT WILL LIKELY BE TRIMMING POPS BACK EVEN FARTHER FOR SAT MORN. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY/... UPPER LEVEL HIGH PRESSURE OVER THE CTRL ATLANTIC SHIFTS TWD THE SE COAST OVER THE WEEKEND. MEANWHILE...AN UPPER TROUGH WILL STAY WELL ROOTED IN THE OH/TN VALLEYS DUE TO AN AMPLIFYING RIDGE OVER THE GREAT BASIN. THE COMBINATION OF THESE UPPER LEVEL FEATURES WITH THE STALLED SFC BOUNDARY ALONG THE CAROLINA COAST WILL CAUSE MOISTURE AND SHORTWAVE ENERGY TO STREAM ACROSS THE MID ATLANTIC REGION SATURDAY THROUGH SUNDAY NIGHT. A CONTINUATION OF FAVORABLE ISENTROPIC LIFT MOVING INTO THE AREA FROM THE SOUTHWEST ON SATURDAY WILL QUICKLY SATURATE THE LOWER ATMOSPHERE AND ACT TO ENHANCE STEADY PRECIPITATION/RAINFALL. PWATS WILL GRADUALLY INCREASE THROUGH THE WEEKEND FROM ROUGHLY 0.75 INCHES NORTH TO 1.50 INCHES SOUTH FOR TONIGHT...TO AROUND 2.00 INCHES NORTH TO 2.35 INCHES SOUTH BY SUNDAY. THE BEST POTENTIAL FOR WIDESPREAD STEADY RAIN IS SATURDAY NIGHT. HOWEVER THE WEEKEND WILL NOT BE A COMPLETE WASHOUT...BUT DO EXPECT PERIODS OF RAIN THAT WILL BE MODERATE TO HEAVY AT TIMES AND MOSTLY CLOUDY TO CLOUDY SKIES. FOR SUNDAY...FORECAST MODELS ARE HINTING AT A DRY SLOT MOVING INTO NE NC AND SE VA DURING THE DAY AS THE ATLANTIC HIGH PUSHES CLOSER TO THE SOUTHEAST COAST. IF THIS OCCURS...THEN THERE COULD BE A NICE REPRIEVE FROM THE RATHER WET WEEKEND RAINS IN THE AFOREMENTIONED AREAS. AT THIS TIME...IT IS DIFFICULT TO PINPOINT EXACTLY WHERE THE DRIER CONDITIONS MAY SET UP AND HAVE THEREFORE KEPT A CHANCE OF PRECIP IN THE ONGOING FORECAST FOR SUNDAY AFTN/EVENING. DUE TO EXTENSIVE CLOUD COVER AND COOLER AMBIENT AIR DUE TO EVAPORATIVE COOLING PROCESSES...TEMPERATURES WILL BE ON THE COOL SIDE WITH HIGHS SAT/SUN GENERALLY IN THE 70S (NEAR 80 NE NC/FAR SE VA ON SUN DUE TO POTENTIAL DRY SLOT/CLEARING). THE LOWS ON SATURDAY NIGHT WILL GENERALLY BE IN THE 60S (NEAR 70 COASTAL NE NC/FAR SE VA). THE OH/TN VALLEY TROUGH AND GREAT BASIN HIGH BOTH BEGIN TO WASH OUT ON MONDAY AND APPEAR TO RESULT IN A PSEUDO-WESTERLY (OR ZONAL) FLOW. AT THIS TIME...IT SHOULD BE ENOUGH TO START PUSHING THE PERSISTENTLY RAINY WX PATTERN OUT OF THE AREA BUT NOT UNTIL TUESDAY/TUESDAY NIGHT. HIGH TEMPERATURES REBOUND INTO THE LOWER 80S SINCE A COMBINATION OF SUN AND CLOUDS ARE ANTICIPATED DURING THE DAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... STRONG UPPER-LEVEL WESTERLY FLOW PREVAILS OVER SOUTHERN CANADA THROUGH THE MIDDLE AND LATER PORTIONS OF NEXT WEEK. UNDERNEATH THIS ZONAL FLOW...MID-LEVEL ANTICYCLONES WILL REMAIN NEARLY STATIONARY OVER THE SOUTHERN PLAINS AND WESTERN ATLANTIC. AN AREA OF (SOMEWHAT) LOWER HEIGHTS IS PROGGED OVER THE APPALACHIAN PLATEAU. HOWEVER...THE MID ATLANTIC REGION SHOULD LARGELY REMAIN UNDER THE INFLUENCE OF THE WESTERN ATLANTIC RIDGE. HENCE... PRECIPITATION POTENTIAL SHOULD BE MINIMAL (NEAR OR BELOW CLIMO) DUE TO A LACK OF LARGE SCALE FORCING FOR STORM ORGANIZATION... DESPITE A WARM AND INCREASINGLY HUMID AIRMASS. HIGH TEMPERATURES SHOULD AVERAGE AROUND SEASONAL NORMALS TUESDAY THROUGH FRIDAY (MID/UPPER 80S)...WITH A FEW 90 DEGREE HIGHS POSSIBLE IN FAVORED HOT SPOTS. LOWS SHOULD PRIMARILY RANGE FROM THE UPPER 60S TO LOW 70S. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... A TROUGH OF LOW PRES ALONG THE MID AND SOUTH ATL COAST CONTINUES TO MOVE NE AND AWAY FROM LAND...RESULTING IN NE FLOW ACROSS THE REGION IN THE LOW LEVELS. ALOFT...SWLY FLOW WILL GRADUALLY INCREASE AND RESULT IN OVERRUNNING MOISTURE THAT WILL GRADUALLY SPREAD NORTH LIKELY STARTING OVERNIGHT INTO SAT MORNING. EXACT TIMING OF THE PRECIP WILL BE TRICKY. CIGS AND VSBY WITH THE RAIN WILL START OUT AS MVFR FOR SOME TIME INITIALLY BUT TRANSITION TO IFR LATER SATURDAY MORNING AND EARLY AFTERNOON AS A WAVE OF LOW PRESSURE MOVES ALONG THE COASTAL FRONT. ONCE CONDITIONS BECOME IFR SATURDAY...THEY WILL LIKELY REMAIN IFR FOR A PERIOD OF TIME WHILE THE OVERRUNNING CONTINUES INTO THE AFTERNOON. && .MARINE... THE LATEST MSAS SURFACE ANALYSIS SHOWS A 1017MB LOW ~110NM ENE OF CAPE HATTERAS TRACKING NE ALONG A COASTAL FRONT ALIGNED PARALLEL TO THE SOUTHEAST COAST. A NE WIND (STRONGEST OFF THE CURRITUCK OUTER BANKS) IS GRADUALLY DIMINISHING AS THE LOW PULLS AWAY AND HIGH PRESSURE RETURNS FROM THE N. ANOTHER LOW (PRESENTLY OVER SOUTHERN GA) IS PROGGED TO LIFT NE ALONG THE SOUTHEAST COAST TONIGHT THROUGH SATURDAY...EVENTUALLY REACHING THE MID ATLANTIC SATURDAY NIGHT AND SUNDAY...BEFORE PULLING TO THE NE SUNDAY NIGHT. THIS PATTERN WILL MAINTAIN A PERSISTENT NE FLOW OVER THE REGION THROUGH SATURDAY NIGHT FOR THE ENTIRE AREA...AND INTO SUNDAY FOR THE NORTHERN PORTION OF THE MARINE AREA. WIND SPEEDS REMAIN CAPPED AROUND 15KT ALONG WITH SEAS/WAVES CAPPED AT 4FT/3FT. CONFIDENCE ON SCA HEADLINES REMAINS LOW...SO NO FLAGS WILL BE ISSUED. ALTHOUGH A FEW BRIEF PERIODS OF SCA WIND ARE POSSIBLE ACROSS THE LOWER BAY (4FT WAVES MOUTH OF THE BAY)...AND 5FT SEAS ARE POSSIBLE OUT NEAR 20NM IN THE OCEAN. HIGH PRESSURE RETURNS EARLY NEXT WEEK WITH LIGHT SSW FLOW RETURNING...ALONG WITH 2-3FT SEAS. PERSISTENT ONSHORE FLOW WILL RESULT IN AN ELEVATED RIP CURRENT RISK SATURDAY AND POSSIBLY INTO SUNDAY AS WELL. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH SATURDAY EVENING FOR MDZ025. NC...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH SATURDAY EVENING FOR NCZ102. VA...MODERATE RIP CURRENT RISK FROM 8 AM EDT SATURDAY THROUGH SATURDAY EVENING FOR VAZ098>100. MARINE...NONE. && $$ SYNOPSIS...MPR NEAR TERM...JDM/MPR SHORT TERM...BMD LONG TERM...AJZ AVIATION...JEF MARINE...AJZ
AREA FORECAST DISCUSSION
NWS SPOKANE WA
1003 PM PDT Fri Aug 16 2013 .SYNOPSIS... A slow moving upper level trough will keep unsettled conditions over the Inland Northwest through Saturday. The trough will pass all areas by Saturday evening and Sunday delivering locally breezy winds. Westerly flow will build over the region through the middle of the week bringing dry weather and seasonable temperatures. The weather will turn more unsettled toward the end of the next work week with a return of some thunderstorms possible. && .DISCUSSION... Evening update: widely scattered to isolated showers and thunderstorms have been found across northeast Oregon and portions of the lower Idaho Panhandle this evening. In the past hour or so more activity has been developing and moving into parts of southeast WA, including Whitman county. The current trajectory suggest some may also slip as far north as southern Spokane and Kootenai county. I`m not thinking they will reach to the Spokane Metro at this time, but there is the a small potential they could clip the Post Falls or Coeur d`Alene area. Timing suggests entering southern Spokane county around 11 pm. These are quick movers, so may produce some brief heavy rain and gusty winds, maybe a little bit of hail. Much of this activity has been found under a ribbon of modest instability and jet streak and subtle mid-level disturbance moving along the slowly-advancing cold front. The RUC13 (and other guidance) continues to show some elevated CAPE and a ribbon of favorable high level total totals across the southeast through the night. Hence the continuing isolated shower and thunder threat through the night. /J. Cote` && .AVIATION... 06Z TAFS: A front will continue to push across the Inland Northwest, bringing some middle and high clouds, as well as the risk for some widely sct to isolated -shra/-tsra. The highest threat among TAF sites will be around KLWS/KPUW...and perhaps KCOE but some may also be found in the vcnty of KGEG/KSFF through the overnight. The main threat, aside from lightning, will be possible gusty winds. Otherwise look for VFR conditions, locally breezy after 18-21Z Saturday, subsiding again late. /J. Cote` && .PRELIMINARY POINT TEMPS/POPS... Spokane 63 84 60 83 60 83 / 10 10 10 0 0 0 Coeur d`Alene 59 84 58 83 56 83 / 10 10 10 0 0 0 Pullman 55 84 52 83 50 86 / 20 10 10 0 0 0 Lewiston 66 92 64 93 62 94 / 20 10 10 0 0 0 Colville 57 88 54 87 53 89 / 10 20 10 0 0 0 Sandpoint 55 82 53 83 50 82 / 10 10 10 0 0 0 Kellogg 58 82 57 81 56 83 / 20 10 10 0 0 0 Moses Lake 61 89 60 88 60 88 / 10 0 0 0 0 0 Wenatchee 66 87 64 88 64 88 / 10 0 0 0 0 0 Omak 61 89 61 89 61 89 / 0 10 10 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
637 PM CDT SUN AUG 18 2013 UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE .SHORT TERM...TONIGHT AND MONDAY ISSUED AT 256 PM CDT SUN AUG 18 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE CENTERED OVER THE NE U.S...BUT WITH A RIDGE AXIS THAT EXTENDS WEST INTO THE GREAT LAKES. THE MAIN STORM TRACK REMAINS NORTH OF THE REGION OVER SOUTHERN CANADA...BUT IS GRADUALLY SINKING TO THE SOUTH. AS THIS OCCURS...A SHORTWAVE OVER EASTERN MONTANA IS MOVING EAST AND PRODUCING THUNDERSTORMS...WHICH WILL TRACK TOWARDS THE REGION TOMORROW. BESIDES TEMPERATURES...SMALL THUNDERSTORM CHANCES REMAIN THE MAIN FORECAST CONCERNS. TONIGHT...THE SHORTWAVE TROUGH OVER EASTERN MONTANA WILL MOVE EAST INTO THE NORTHERN MISSISSIPPI VALLEY BY 12Z MONDAY. THE 850MB MOISTURE AND INSTABILITY AXES WILL SHIFT INTO NORTHEAST MINNESOTA BY THIS TIME...WHICH LOOKS TOO FAR WEST FOR MUCH OF AN IMPACT ON THE FORECAST AREA. OTHERWISE...SCATTERED HIGH CLOUDS WILL BE PASSING OVERHEAD FOR MUCH OF NIGHT...AND THEN SEE THE HIGH CLOUDS THICKEN AND LOWER A BIT LATE AS THE SHORTWAVE DRAWS CLOSER. THE PRESSURE GRADIENT WILL BE TIGHTENING TONIGHT...WHICH SHOULD ALLOW A LIGHT SW WIND TO PERSIST AND KEEP ANY FOG FROM FORMING. LOWS WILL CONTINUE THEIR WARMING TREND...AND RESIDE IN THE 50S. MONDAY...THE SHORTWAVE TROUGH WILL MOVE INTO WISCONSIN. FORCING WITH THE WAVE APPEARS TO SUBTLY WEAKEN...SO WILL LIKELY NEED THE HELP OF DIURNAL INSTABILITY TO GET CONVECTION GOING. THE MOISTURE AXIS WILL BE SNEAKING INTO NORTH-CENTRAL WISCONSIN IN THE AFTERNOON...BUT PROGGED NAM SOUNDINGS AT 21Z NEAR EAGLE RIVER SHOW DECENT CAPPING CENTERED AT ABOUT 800 MB. USING A PARCEL OF 82/62...ML CAPES WILL REACH AROUND 1000 J/KG...WHILE CINS REMAIN A ROBUST 70-80 J/KG. UNLESS THE CAP IS ADVERTISED TOO STRONGLY...CANNOT SEE MORE THAN ISOLATED STORM DEVELOPMENT GIVEN THE WEAK FORCING. IF STORMS DO DEVELOP...WEAK SHEAR ALOFT WILL KEEP THE SEVERE THREAT RATHER LOW. MADE ONLY MINOR TWEAKS TO TIMING AND COVERAGE OF POPS. DESPITE AN INCREASE IN CLOUD COVER...LOW LEVEL TEMPS WILL ALSO BE WARMING...AND PUSH HIGHS INTO THE MIDDLE 80S. .LONG TERM...MONDAY NIGHT THROUGH SUNDAY ISSUED AT 256 PM CDT SUN AUG 18 2013 TUESDAY THROUGH NEXT WEEKEND WILL BE HIGHLIGHTED WITH ABOVE NORMAL TEMPERATURES. THE NEXT MAIN CHANCE FOR WIDESPREAD PRECIPITATION WILL BE STARTING WEDNESDAY AFTERNOON OVER NORTHWEST WISCONSIN THEN OVER THE REST OF THE STATE WEDNESDAY NIGHT INTO THURSDAY WITH THE PASSAGE OF A COLD FRONT. THERE IS A SMALLER CHANCE OF CONVECTION ON TUESDAY OVER THE NORTHWEST HALF OF THE STATE DUE TO CONTINUED WAA...AND IN A REGION OF UPPER DIVERGENCE AHEAD OF THE WESTERLIES OVER THE NORTHERN PLAINS. CONVECTION MAY BE CONFINED TOWARD WESTERN PORTION OF THE STATE BUT WILL LEAVE PARTS OF NC WI WITH SMALL CHANCE DUE TO TOTAL TOTALS INCREASE IN THE AFTERNOON. THE WESTERLY FLOW OVER THE NORTHERN PLAINS BEGINS TO BUCKLE WEDNESDAY AS A SHORT WAVE TROUGH DEVELOPS OVER SOUTHERN CANADA AND A COLD FRONT SAGS INTO THE NORTHERN GREAT LAKES REGION INCLUDING NORTHWEST WISCONSIN. MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT WITH THE TIMING OFF THIS FRONT AND CONVECTION UNTIL WEDNESDAY NIGHT FOR MOST LOCATIONS EXCEPT NORTH CENTRAL WISCONSIN. SEVERE POTENTIAL REMAINS FOR WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. TOTAL TOTALS CLIMB INTO THE LOWER 50S WITH THE FRONT WHILE PWATS INCREASE TO NEAR 2.00 GFS...GEM DROP THE CONVECTION AND FRONT WELL SOUTH ON THURSDAY FOR A DRIER TREND WHICH COULD LAST INTO FRIDAY. BUT THE ECMWF SLOWS THIS FRONT DOWN WHILE A HIGH PRESSURE SYSTEM DRIFTS OVER THE NORTHERN GREAT LAKES REGION THURSDAY THROUGH FRIDAY. THE UPPER RIDGE CONTINUES TO BUILD INTO THE WEEKEND FOR MORE HEAT ALONG WITH CHANCES OF CONVECTION ON THE PERIPHERY OF THE RIDGE OR MAINLY THE NORTHERN GREAT LAKES REGION. && .AVIATION...FOR 00Z TAF ISSUANCE ISSUED AT 635 PM CDT SUN AUG 18 2013 VFR CONDITIONS EXPECTED AS ANTICYCLONE SLOWLY SHIFTS SE OF THE AREA. ADDED SOME GUSTINESS TO THE TAFS FOR TOMORROW WHEN FAIRLY DEEP MIXING IS EXPECTED TO OCCUR. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
536 PM CDT SAT AUG 17 2013 UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE .SHORT TERM...TONIGHT AND SUNDAY ISSUED AT 230 PM CDT SAT AUG 17 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE STRETCHING FROM NEW ENGLAND TO THE WESTERN GREAT LAKES. SHOWERS AND STORMS ARE OCCURRING OVER SOUTHERN CANADA WITHIN THE MAIN BELT OF WESTERLIES AND ALSO OVER THE OHIO VALLEY THANKS TO AN UPPER LEVEL LOW PRESSURE SYSTEM. CONDITIONS ARE QUIET ACROSS WISCONSIN WITH ONLY DIURNAL CU POPPING. CHANGES ARE MINIMAL OVER THE NEXT 24 HOURS...SO TEMPS AND CLOUDS REMAIN THE MAIN FORECAST CONCERNS. TONIGHT...AN UPPER LEVEL RIDGE AXIS WILL BE EXTENDING ACROSS THE NORTHERN GREAT LAKES WHILE THE SURFACE RIDGE AXIS WILL BE OVER SOUTHERN WISCONSIN. THE CENTER OF THE SURFACE HIGH WILL BE A LITTLE FARTHER TO THE EAST COMPARED TO LAST NIGHT...WHICH MAY ALLOW A SLIGHT SW WIND TO STICK AROUND. THE MAIN BELT OF WESTERLIES WILL REMAIN POSITIONED TO OUR NORTH OVER MANITOBA AND ONTARIO AND SOME HIGH CLOUDS MAY DRIFT ACROSS NORTHERN WISCONSIN. NEITHER THE WIND NOR HIGH CLOUDS SHOULD IMPACT TEMPS MUCH WHICH WILL BE A COUPLE DEGREES WARMER THAN LAST NIGHT. PATCHY GROUND FOG SHOULD ALSO DEVELOP LATE...THAT WILL BE A LITTLE MORE WIDESPREAD OVER N-C WISCONSIN COMPARED TO ELSEWHERE. SUNDAY...THOUGH RIDGING IN THE UPPER LEVELS WILL BE OVERHEAD...SURFACE HIGH PRESSURE WILL DRIFT A LITTLE FARTHER EAST IN RESPONSE TO HEIGHT FALLS OCCURRING OVER THE FAR NORTHERN PLAINS AND LAKE SUPERIOR REGION. SHOULD SEE A LITTLE MORE HIGH CLOUDS IN ADDITION TO THE DIURNAL CU THAT WILL POP MIDDAYISH. MIXING HEIGHTS ARE PROJECTED TO BE A LITTLE LOWER TOMORROW AFTERNOON...BUT LOWS WILL BE A LITTLE WARMER...SO WILL GO WITH HIGHS ABOUT A DEGREE WARMER THAN TODAY. .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY ISSUED AT 230 PM CDT SAT AUG 17 2013 UPPER RIDGING ACROSS THE WESTERN TWO THIRDS OF THE COUNTRY WILL LEAD TO WARMER TEMPERATURES BUT MINIMAL PRECIPITATION CHANCES FOR MUCH OF THE NEW WORK WEEK. THE NORTHERN STREAM ACROSS CANADA WILL BE THE PRIMARY SOURCE OF SYSTEMS WHICH MAY BRUSH OVER THE NORTHERN GREAT LAKES REGION AT TIMES. THE NAM AND GFS CONTINUE TO FOLLOW THE TREND OF A FEW WEAK SHORT WAVES GLANCING OVER NORTHERN WISCONSIN IN THE SUBTLE WAA FLOW FOR LATE TONIGHT INTO MONDAY WITH ANOTHER TOWARD TUESDAY AFTERNOON. PROGS CONTINUE TO INDICATE A STRONGER SHORT WAVE TROUGH WITH COLD FRONT SLIDING OVER THE GREAT LAKES REGION WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. TOTAL TOTALS CLIMB TO NEAR 50 ALONG AND NEAR THE FRONT...SO NO NEED TO CHANGE THE GOING THOUGHTS OF SVR POTENTIAL IN THE HWO AT THIS TIME. PCPN MAY END THURSDAY INTO THURSDAY NIGHT DEPENDING ON THE SOUTHWARD EXTENT OF THE FRONT BUT RETURN FLOW SETTING UP IN THE WAKE OF A SUBTLE HIGH PRESSURE SYSTEM WILL BRING THE POTENTIAL OF MORE SHOWERS AND STORMS BACK INTO THE AREA BY NEXT WEEKEND. && .AVIATION...FOR 00Z TAF ISSUANCE ISSUED AT 533 PM CDT SAT AUG 17 2013 SFC HIGH WILL BE A LITTLE FARTHER OFF TO THE SE TNGT...SO THERE WL BE A BIT OF A SFC PRESSURE GRADIENT ACRS THE AREA...BUT PROBABLY NOT ENOUGH TO PREVENT DECOUPLING AND WINDS GOING CALM AT MOST LOCATIONS. EXPECT SOME MIFG TO DEVELOP AGAIN TNGT. GIVEN CHGS DESCRIBED ABV...CONDITIONS ACRS N-C WI WL BE A BIT LESS FAVORABLE THAN YDA. .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......SKOWRONSKI
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND SUNDAY ISSUED AT 230 PM CDT SAT AUG 17 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE STRETCHING FROM NEW ENGLAND TO THE WESTERN GREAT LAKES. SHOWERS AND STORMS ARE OCCURRING OVER SOUTHERN CANADA WITHIN THE MAIN BELT OF WESTERLIES AND ALSO OVER THE OHIO VALLEY THANKS TO AN UPPER LEVEL LOW PRESSURE SYSTEM. CONDITIONS ARE QUIET ACROSS WISCONSIN WITH ONLY DIURNAL CU POPPING. CHANGES ARE MINIMAL OVER THE NEXT 24 HOURS...SO TEMPS AND CLOUDS REMAIN THE MAIN FORECAST CONCERNS. TONIGHT...AN UPPER LEVEL RIDGE AXIS WILL BE EXTENDING ACROSS THE NORTHERN GREAT LAKES WHILE THE SURFACE RIDGE AXIS WILL BE OVER SOUTHERN WISCONSIN. THE CENTER OF THE SURFACE HIGH WILL BE A LITTLE FARTHER TO THE EAST COMPARED TO LAST NIGHT...WHICH MAY ALLOW A SLIGHT SW WIND TO STICK AROUND. THE MAIN BELT OF WESTERLIES WILL REMAIN POSITIONED TO OUR NORTH OVER MANITOBA AND ONTARIO AND SOME HIGH CLOUDS MAY DRIFT ACROSS NORTHERN WISCONSIN. NEITHER THE WIND NOR HIGH CLOUDS SHOULD IMPACT TEMPS MUCH WHICH WILL BE A COUPLE DEGREES WARMER THAN LAST NIGHT. PATCHY GROUND FOG SHOULD ALSO DEVELOP LATE...THAT WILL BE A LITTLE MORE WIDESPREAD OVER N-C WISCONSIN COMPARED TO ELSEWHERE. SUNDAY...THOUGH RIDGING IN THE UPPER LEVELS WILL BE OVERHEAD...SURFACE HIGH PRESSURE WILL DRIFT A LITTLE FARTHER EAST IN RESPONSE TO HEIGHT FALLS OCCURRING OVER THE FAR NORTHERN PLAINS AND LAKE SUPERIOR REGION. SHOULD SEE A LITTLE MORE HIGH CLOUDS IN ADDITION TO THE DIURNAL CU THAT WILL POP MIDDAYISH. MIXING HEIGHTS ARE PROJECTED TO BE A LITTLE LOWER TOMORROW AFTERNOON...BUT LOWS WILL BE A LITTLE WARMER...SO WILL GO WITH HIGHS ABOUT A DEGREE WARMER THAN TODAY. .LONG TERM...SUNDAY NIGHT THROUGH SATURDAY ISSUED AT 230 PM CDT SAT AUG 17 2013 UPPER RIDGING ACROSS THE WESTERN TWO THIRDS OF THE COUNTRY WILL LEAD TO WARMER TEMPERATURES BUT MINIMAL PRECIPITATION CHANCES FOR MUCH OF THE NEW WORK WEEK. THE NORTHERN STREAM ACROSS CANADA WILL BE THE PRIMARY SOURCE OF SYSTEMS WHICH MAY BRUSH OVER THE NORTHERN GREAT LAKES REGION AT TIMES. THE NAM AND GFS CONTINUE TO FOLLOW THE TREND OF A FEW WEAK SHORT WAVES GLANCING OVER NORTHERN WISCONSIN IN THE SUBTLE WAA FLOW FOR LATE TONIGHT INTO MONDAY WITH ANOTHER TOWARD TUESDAY AFTERNOON. PROGS CONTINUE TO INDICATE A STRONGER SHORT WAVE TROUGH WITH COLD FRONT SLIDING OVER THE GREAT LAKES REGION WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. TOTAL TOTALS CLIMB TO NEAR 50 ALONG AND NEAR THE FRONT...SO NO NEED TO CHANGE THE GOING THOUGHTS OF SVR POTENTIAL IN THE HWO AT THIS TIME. PCPN MAY END THURSDAY INTO THURSDAY NIGHT DEPENDING ON THE SOUTHWARD EXTENT OF THE FRONT BUT RETURN FLOW SETTING UP IN THE WAKE OF A SUBTLE HIGH PRESSURE SYSTEM WILL BRING THE POTENTIAL OF MORE SHOWERS AND STORMS BACK INTO THE AREA BY NEXT WEEKEND. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1228 PM CDT SAT AUG 17 2013 VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER OVER THE TAF PERIOD. MOS GUIDANCE SHOWS THAT PATCHY GROUND FOG DOES NOT LOOK TO BE AS DENSE OR WIDESPREAD BETWEEN 08-12Z SUNDAY MORNING COMPARED TO THIS MORNING. STILL EXPECT MORE FOG OVER NORTH-CENTRAL WISCONSIN COMPARED TO ELSEWHERE THOUGH. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......MPC
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1048 AM CDT SAT AUG 17 2013 .UPDATE...ANOTHER QUIET DAY IN STORE FOR SOUTHERN WISCONSIN. CHANGES IN THE TODAY PERIOD WERE LIMITED TO ADJUSTING FOR TRENDS. SKY COVER WAS BUMPED UP A BIT...WITH AT LEAST SCATTERED CUMULUS EXPECTED GIVEN PROXIMITY SOUNDINGS AND RESIDUAL LOW-LEVEL MOISTURE...CU RULE...AND GOES-R PG WRF ABI SYNTHETIC IMAGERY. GIVEN HIGHS YESTERDAY AND RAP PROXIMITY SOUNDINGS...NEAR GROUND SUPERADIABATIC LAPSE RATES ARE ANTICIPATED. THIS WILL RESULT IN FORECAST HIGHS REMAINING AROUND 80/LOW 80S AWAY FROM THE LAKESHORE COUNTIES...TO MID/UPPER 70S FAR EAST. ET && .AVIATION/18Z TAFS/...VFR CONDITIONS ARE EXPECTED THIS AFTERNOON AND THIS EVENING ACROSS TAF SITES...AND AGAIN FOR MOST OF SUNDAY. HIGH PRESSURE WILL REMAIN SOUTHEAST OF THE REGION THROUGH THE WEEKEND. THE HIGH WILL BRING QUIET WEATHER. SCATTERED DIURNAL CUMULUS CLOUDS ARE EXPECTED THIS AFTERNOON AND AGAIN SUNDAY AFTERNOON. LIGHT SOUTHEAST WINDS ARE EXPECTED THIS AFTERNOON INTO THE EARLY EVENING...THEN BECOMING LIGHT/CALM TONIGHT INTO EARLY SUNDAY. LIGHT SOUTH WINDS ARE EXPECTED AT MADISON ON SUNDAY...WITH LIGHT SOUTHEAST WINDS AT THE EASTERN SITES. FOG WITH VISIBILITIES DOWN TO OR BELOW AIRPORT MINIMUMS ARE EXPECTED AT KENOSHA BY 05Z SUNDAY...LINGERING UNTIL AROUND 13Z SUNDAY. MAY SEE FOG WITH VISIBILITIES DOWN TO ALTERNATE MINIMUMS AT TIMES AT WAUKESHA FROM 09Z UNTIL 12Z SUNDAY. MADISON AND MILWAUKEE MAY SEE VFR FOG DURING THIS TIME. WOOD && .PREV DISCUSSION... /ISSUED 326 AM CDT SAT AUG 17 2013/ SHORT TERM... TODAY AND TONIGHT...FORECAST CONFIDENCE HIGH AT THE SFC...HIGH PRESSURE WILL CONTINUE TO PREVAIL FROM NEW ENGLAND WWD INTO PORTIONS OF THE UPPER MS RIVER VALLEY...INCLUDING SRN WI. ALOFT...AN UPPER LOW WILL REMAIN OVER THE MID MS RIVER VALLEY WITH SOME RIDGING AND WARMING ALOFT THAT WILL OVERSPREAD SRN WI FROM THE NRN PLAINS. THIS WILL RESULT IN LESS CU DEVELOPMENT THAN RECENT DAYS WITH A CONTINUED DRY AND WARMING AIRMASS IN PLACE. NEAR GROUND SUPERADIABATIC LAPSE RATES WITH 925 MB TEMPS AROUND 19C YIELDS LOWER 80S FOR TODAY INLAND FROM THE LAKE BREEZE. LAKE BREEZE WILL DEVELOP BY 15Z SIMILAR TO YESTERDAY. GOOD RADIATIONAL COOLING CONDITIONS ONCE AGAIN TNT BUT AIRMASS IS FAIRLY DRY SO EXPECT GROUND FOG ONLY IN THE TYPICAL LOW LYING AREAS. SUNDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE HIGH. SURFACE HIGH PRESSURE WILL CONTINUE TO HOLD STRONG OVER THE GREAT LAKES REGION THROUGH EARLY NEXT WEEK BRINGING MOSTLY CLEAR SKIES AND DRY WEATHER. MEANWHILE...A WEAK MID LEVEL LOW WILL DRIFT ACROSS THE OHIO RIVER VALLEY AND ALLOW FOR THAT STRONG AND WARM RIDGE OVER THE WESTERN U.S. TO NOSE INTO SOUTHERN WISCONSIN. LOOK FOR A GRADUAL WARMING TREND THROUGH THIS PERIOD...FROM AROUND 80 SUNDAY TO THE UPPER 80S/90 ON WEDNESDAY. A FEW WEAK UPPER TROUGHS ARE FORECAST BY THE MODELS TO RIDE OVER THE RIDGE AND PASS ACROSS THE GREAT LAKES NEXT WEEK. THE FIRST WAVE MONDAY NIGHT WILL BE DRY WITH PLENTY OF AGREEMENT BETWEEN THE MODELS WHERE THEY ALL SHOW A STRONG CAP AROUND 750MB. LONG TERM... WEDNESDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM TO LOW. THERE IS A STRONG UPPER TROUGH THAT WILL RIDE OVER THE RIDGE THROUGH SOUTHERN CANADA MID WEEK. THIS WILL BE OUR NEXT WEATHER MAKER AS IT REACHES LAKE SUPERIOR WED NIGHT. THERE ARE SOME SIGNIFICANT DIFFERENCES BETWEEN THE MODELS FOR WED NIGHT/THU NOW. THE GFS PHASES THAT UPPER TROUGH WITH A WEAKER SHORTWAVE MOVING THROUGH THE NORTHERN PLAINS/UPPER MIDWEST AND DROPS A COLD FRONT ALL THE WAY DOWN THROUGH WI INTO IA AND IL. THE LATEST 00Z ECMWF DOES NOT PHASE THOSE TWO FEATURES SO THE FRONT SAGS INTO SOUTHERN WI ON THU AND THEN GETS PUSHED BACK NORTH FOR FRI. THE CANADIAN MODEL IS SOMEWHERE IN BETWEEN. THE ECMWF WOULD SUGGEST THAT AT LEAST THE SOUTHERN HALF OF THE MKX FORECAST AREA WOULD STAY DRY AND VERY WARM THROUGH THE LATTER HALF OF NEXT WEEK...HIGHS IN THE LOWER 90S. THE GFS SUGGESTS A PERIOD OF THUNDERSTORMS ALONG THE FRONT AND THEN COOLING BACK OFF INTO THE UPPER 70S ON FRI. STAY TUNED. AVIATION/12Z TAFS/...DENSE FOG AT KENW WILL CONTINUE UNTIL SUNRISE...THEN QUICKLY BURN OFF. POSSIBLY BRIEF MVFR VSBYS MAY OCCUR AT KMSN AND KUES AROUND SUNRISE. OTHERWISE FEW-SCT FAIR WX CU AROUND 6-8 KFT DURING THE AFTERNOON. ANOTHER CLEAR NIGHT WITH HIGH PRESSURE IN CONTROL. FOG EXPECTED IN THE TYPICAL LOW LYING AREAS SO EXPECT KENW TO HAVE DENSE FOG AT TIMES LATE AT NIGHT WITH MVFR VSBYS POSSIBLY AROUND SUNRISE SUNDAY AT KMSN AND KUES. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ UPDATE...ET/WOOD TODAY/TONIGHT AND AVIATION/MARINE...GEHRING SUNDAY THROUGH FRIDAY...MRC
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1110 PM CDT FRI AUG 16 2013 UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE .SHORT TERM...TONIGHT AND SATURDAY ISSUED AT 241 PM CDT FRI AUG 16 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOWS A SPRAWLING HIGH PRESSURE SYSTEM STRETCHING FROM THE NORTHERN MISSISSIPPI VALLEY TO NEW ENGLAND. AS ONE SHORTWAVE DIGS OVER THE SOUTHERN PLAINS WHILE ANOTHER SHIFTS EAST OVER MANITOBA...MID-LEVEL RIDGING IS GRADUALLY BUILDING EAST OVER THE NORTHERN PLAINS. THIS PATTERN WILL CONTINUE TO LEAD TO QUIET WEATHER OVER THE NEXT SEVERAL DAYS...MAKING CLOUDS AND TEMPS THE MAIN FORECAST CONCERN IN THE SHORT TERM. TONIGHT...HIGH PRESSURE WILL REMAIN OVER THE REGION BENEATH BUILDING HEIGHTS IN THE MID AND UPPER LEVELS. WISCONSIN WILL BE POSITIONED BETWEEN WEATHER SYSTEMS NORTH AND SOUTH OF THE REGION. WITH LOW PWATS AND MOSTLY CLEAR CONDITIONS...WILL LIKELY SEE PATCHY GROUND FOG FORM LATE TONIGHT ACROSS THE SANDY SOIL AREAS AND RIVER VALLEYS. WENT BELOW MOS GUIDANCE FOR LOWS...WHICH SHOULD BE A FEW DEGREES WARMER THAN LAST NIGHT. SATURDAY...HIGH PRESSURE THROUGH THE COLUMN WILL PROVIDE ANOTHER QUIET AND SUNNY DAY. START TO GET A LITTLE MORE RETURN FLOW ACROSS THE REGION...WHICH SHOULD LEAD TO SLIGHTLY WARMER HIGH TEMPS AND MORE HUMIDITY. HIGHS MAINLY IN THE LOW TO MID 80S...EXCEPT COOLER NEAR THE LAKE. .LONG TERM...SATURDAY NIGHT THROUGH FRIDAY ISSUED AT 241 PM CDT FRI AUG 16 2013 MODELS ARE NOW IN GOOD AGREEMENT WITH OVERALL PATTERN. THEY BRING UPPER RIDGING INTO THE NORTHERN PLAINS AND WESTERN GREAT LAKES THROUGH MIDWEEK. A SHORT WAVE TROUGH MOVING ALONG THE CANADIAN BORDER WILL SUPPRESS THE RIDGING A BIT SUNDAY NIGHT AND MONDAY AND COULD PRODUCE SCATTERED THUNDERSTORMS IN THE FAR NORTH. PROLONGED SOUTHERLY FLOW AND WARMER TEMPERATURES ALOFT WILL COMBINE TO PRODUCE VERY WARM AND MORE HUMID CONDITIONS DURING THE MIDDLE OF THE WEEK WITH THE WARMEST WEATHER SINCE MID JULY. THE HEAT SHOULD SUBSIDE AS A COLD FRONT MOVES THROUGH THURSDAY AND THURSDAY NIGHT. COOLER AND DRIER AIR EXPECTED FRIDAY THROUGH SUNDAY. && .AVIATION...FOR 06Z TAF ISSUANCE ISSUED AT 1107 PM CDT FRI AUG 16 2013 HIGH PRESSURE AND VFR CONDITIONS WILL PROVIDE GOOD FLYING WEATHER THROUGH MOST OF THIS TAF PERIOD. THE EXCEPTION WILL BE OVERNIGHT...WHEN SOME SOME PATCHY GROUND FOG WILL IMPACT THE REGION THROUGH ABOUT 12Z/SAT. THE FOG SHOULD BE MOST WIDESPREAD AND DENSE OVER NORTH CENTRAL WISCONSIN. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......RDM AVIATION.......KIECKBUSCH
AREA FORECAST DISCUSSION
NWS CHEYENNE WY
412 PM MDT SAT AUG 17 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 412 PM MDT SAT AUG 17 2013 VISIBLE SATELLITE IMAGERY SHOWS A HIGH LAYER OF SMOKE CONTINUING TO MOVE SOUTHEAST OVER MUCH OF THE FORECAST AREA TODAY...WITH SOME CU DEVELOPING OVER THE MOUNTAINS ON THE WESTERN PERIPHERY OF THE SMOKE LAYER. LLVL INSTABILITY LOOKS WEAK OUT WEST BUT LAPSE RATES ARE QUITE STEEP WITH SFC TEMPERATURES WARMING INTO THE MID TO UPPER 80S. WITH AN UPPER LEVEL SHORTWAVE MOVING UP FROM UTAH...COULD SEE SOME MORE VIGOROUS CU TOWERS DEVELOP INTO ISOLATED SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON AND EARLY EVENING MAINLY ALONG AND WEST OF THE LARAMIE RANGE. RUC MODEL HINTS AT A FEW TRYING TO DEVELOP ACROSS THE EASTERN PLAINS AS WELL IN MOIST UPSLOPE FLOW...BUT AM NOT CONFIDENT THE CAP WILL BREAK IN THIS AREA TO DEVELOP MUCH MORE THAN VERY LIGHT SHOWERS. 12Z UPSTREAM RAOBS AND NAM FORECAST OBS SUGGEST A VERY DEEP MIXING LAYER UP TO 500 MB OR SO THIS AFTERNOON...HOWEVER WINDS ALOFT REMAIN WEAK. CURRENTLY SEEING A FEW LOCATIONS ACROSS THE REGION GUSTING 20 TO 25 MPH OR SO...AND THINK THAT WILL CONTINUE TO BE THE TREND THROUGH THE REST OF THE AFTERNOON. HUMIDITIES HAVE DROPPED TO THE UPPER SINGLE DIGITS TO LOW TEENS WITHIN THE LEESIDE TROUGH AND POINTS FURTHER WEST IN THE ZONE OF GUSTY WINDS...BUT AGAIN WINDS SHOULD REMAIN BELOW CRITICAL FIRE WEATHER THRESHOLDS SO WILL JUST CONTINUE TO MENTION HEIGHTENED FIRE WEATHER CONCERNS FOR LATE THIS AFTERNOON. THE LEESIDE PRESSURE TROUGH WILL REMAIN OVER THE CWA TONIGHT...WITH MOIST SOUTH TO SOUTHEAST FLOW TO CONTINUE OVER THE EASTERN PLAINS. WILL GO WITH THE A PERSISTENCE FORECAST WHICH MEANS THE LOW STRATUS DECK AND FOG WILL RETURN FOR EASTERN PORTIONS OF THE NEBRASKA PANHANDLE EARLY SUNDAY MORNING. SIMILAR TO THE PREVIOUS COUPLE OF NIGHTS...THE FOG COULD BE DENSE AT TIMES WITH VISIBILITIES DROPPING TO ONE HALF MILE OR LESS. THE STRATUS WILL STEADILY MIX OUT AFTER SUNRISE. A STRONGER SHORTWAVE WILL MOVE EAST ACROSS THE NORTHERN ROCKIES AND PLAINS ON SUNDAY AND WILL DROP A WEAK COOL FRONT ACROSS THE FORECAST AREA LATE SUNDAY AFTERNOON AND EVENING. AHEAD OF THE FRONT...WILL SEE BREEZY CONDITIONS RETURN TO THE FORECAST AREA IN THE AFTERNOON. GUIDANCE SUGGESTS THE RETURN OF THE MONSOONAL PLUME TOMORROW AS WELL SO AFTERNOON HUMIDITIES WILL NOT DRY OUT AS MUCH AS TODAY. HOWEVER...CONDITIONS WILL REMAIN DRY AND BREEZY ALONG AND WEST OF THE LARAMIE RANGE SO FIRE WEATHER CONCERNS WILL REMAIN ELEVATED THROUGH EARLY SUNDAY AFTERNOON. THE INCREASE IN MOISTURE AND FRONT MOVING SOUTH ACROSS THE REGION WILL BRING A BROADER COVERAGE OF SHOWERS AND TSTORMS TO THE FORECAST AREA LATE IN THE AFTERNOON AND EVENING. LOOKING AT MODERATE RAINFALL ALONG WITH GUSTY WINDS FROM THIS ACTIVITY. WINDS BEHIND THE FRONT WILL QUICKLY VEER FROM THE NORTH BACK TO THE SOUTHEAST ON MONDAY BUT WILL REMAIN RELATIVELY LIGHT UNDER WEAK FLOW ALOFT WITH MINIMAL ENERGY MOVING OVERHEAD. SO COULD SEE A FEW AFTERNOON SHOWERS AND THUNDERSTORMS ONCE AGAIN IN THIS WEAK UPSLOPE REGIME...BUT COVERAGE WILL BE LESS THAN SUNDAY DUE TO LACK OF SIGNIFICANT FORCING. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 412 PM MDT SAT AUG 17 2013 LOOKS LIKE A TRANSITION TO A MORE MOIST AND WETTER PATTERN COULD BE IN STORE FOR THE EXTENDED ESPECIALLY WEDNESDAY INTO FRIDAY. RIDGE WILL BE CENTERED AROUND COLORADO ON TUESDAY WITH THE BEST MONSOONAL MOISTURE TO THE SOUTHWEST ACROSS WESTERN COLORADO AND UTAH. BOTH THE GFS AND ECMWF HAVE THE RIDGE SHIFTING EASTWARD TOWARD THE CENTRAL PLAINS BY LATE WEDNESDAY AND INTO THURSDAY. THIS CAUSES MIDLEVEL FLOW TO GO SOUTHERLY WITH 700-500MB MOISTURE ON THE INCREASE. AT THE SAME TIME...A SFC HIGH WILL BE POSITIONED OVER THE DAKOTAS BY WEDNESDAY NIGHT WITH EAST WINDS TRANSPORTING HIGHER SFC DEWPOINTS UP ALONG THE LARAMIE RANGE. HAVE CHANCE TO SLIGHT CHANCE POPS OVER MUCH OF SOUTHEAST WY ON WEDNESDAY AND THURSDAY AFTNS AND EVENINGS WITH PW VALUES RISING UP TO AROUND 1 INCH. WHILE CAPE VALUES ARE NOT PARTICULARLY HIGH (LESS THAN 1000 J/KG)...STEERING FLOW IS WEAK (AROUND 10-15 KTS) SO HEAVY RAIN WILL BE THE PRIMARY THREAT. TUESDAY WILL LIKELY BE THE WARMEST AND DRIEST DAY BEFORE INCREASING MOISTURE AND CLOUD COVER CAUSE HIGHS TO FALL AROUND 5-10 DEGREES FOR WEDNESDAY THROUGH FRIDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY MORNING) ISSUED AT 412 PM MDT SAT AUG 17 2013 VFR CONDITIONS WILL OCCUR OVER THE REGION TODAY AND MUCH OF TONIGHT...WITH A FEW ISOLATED THUNDERSTORMS POSSIBLE OVER THE MOUNTAINS LATE THIS AFTERNOON AND EARLY EVENING. WIND GUSTS TO AROUND 20 KTS ARE LIKELY THIS AFTERNOON AT MOST TERMINALS AND WILL EASE THROUGH THE EARLY EVENING. FOR LATE TONIGHT...PATCHY FOG AND LOW CIGS WILL MAKE A RETURN TO THE NEBRASKA PANHANDLE WITH MVFR TO IFR CONDITIONS EXPECTED IN THIS AREA. CONDITIONS WILL IMPROVE LATE SUNDAY MORNING...WITH A BROADER COVERAGE OF SHOWERS AND THUNDERSTORMS EXPECTED LATE SUNDAY AFTERNOON OVER MUCH OF THE FORECAST AREA. && .FIRE WEATHER... ISSUED AT 412 PM MDT SAT AUG 17 2013 AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL REMAIN OVERHEAD THROUGH EARLY NEXT WEEK AND WILL MAINTAIN ABOVE NORMAL TEMPERATURES THROUGH THIS TIME. MOSTLY DRY CONDITIONS WILL CONTINUE FOR THE REST OF THIS EVENING OUTSIDE OF AN ISOLATED THUNDERSTORM OR TWO DEVELOPING OVER THE MOUNTAINS. AFTERNOON HUMIDITIES HAVE DROPPED TO BETWEEN 5 AND 15 PERCENT ALONG AND WEST OF THE LARAMIE RANGE WITHIN A DRY AND WELL MIXED ENVIRONMENT. IN ADDITION...WINDS IN THIS AREA ARE GUSTING BETWEEN 20 AND 25 MPH AT TIMES. DRY CONDITIONS WILL PERSIST THROUGH LATE THIS AFTERNOON BUT WINDS SHOULD STEADILY EASE. THEREFORE...THESE HEIGHTENED FIRE WEATHER CONDITIONS ARE EXPECTED TO IMPROVE THROUGH THE REMAINDER OF TODAY. FOR SUNDAY...MORE MIDLEVEL MOISTURE WILL MOVE OVERHEAD WHICH WILL KEEP AFTERNOON HUMIDITIES BETWEEN 15 AND 20 PERCENT. GUSTS WILL ONCE AGAIN BE AROUND 20 TO 25 MPH AND WILL BECOME MORE WIDESPREAD OVER AND NEAR THE MOUNTAINS IN THE AFTERNOON. IN ADDITION...A WEAK FRONT MOVING SOUTH ACROSS THE DISTRICT WILL BRING A BETTER COVERAGE OF SHOWERS AND THUNDERSTORMS IN THE LATE AFTERNOON AND EVENING. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...NONE. NE...NONE. && $$ SHORT TERM...RJM LONG TERM...FINCH AVIATION...RJM FIRE WEATHER...RJM
AREA FORECAST DISCUSSION
NWS PHOENIX AZ
955 PM MST SUN AUG 18 2013 .SYNOPSIS... VERY WARM DAYS WITH A RELATIVELY HIGH DEGREE OF MONSOON MOISTURE WILL CONTINUE THE THREAT OF AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS THIS WEEK OVER SOUTHWEST AND SOUTH CENTRAL ARIZONA. SHOWER INTENSITY AND COVERAGE WILL VARY FROM DAY TO DAY. A VERY WARM AIRMASS OVER THE REGION HAS THE POTENTIAL TO RESULT IN DESERT HIGH TEMPERATURES NEAR THE 110 DEGREE MARK THROUGH THURSDAY. && .DISCUSSION... UPPER LEVEL LOW CENTERED JUST OFF THE CENTRAL CALIFORNIA COAST HELPED ADVECT MOISTURE INTO THE MOHAVE DESERT REGION TODAY ALONG WITH UPPER LEVEL DIFFLUENCE TO AID STORM DEVELOPMENT. IT ALSO PROVIDED SOME VERTICAL WIND SHEAR TO AID IN STORM INTENSITY. MOST OF THE ACTIVITY WAS OUTSIDE OF OUR FORECAST AREA IN VEF CWA. HOWEVER...ON THE EASTERN PERIPHERY OF THE INFLUENCE FROM THE UPPER LOW...SOUTHERN ARIZONA HAD ANOTHER FAIRLY ACTIVE NIGHT. WHILE OUTFLOWS DID MAKE THEIR WAY THROUGH THE PHOENIX METRO AREA...ONLY ISOLATED STORMS HAVE MANAGED TO FORM...THIS TIME OVER THE WEST VALLEY. IR IMAGERY SHOWS A LARGE AREA OF COLD CLOUD TOPS...FROM DECAYING CONVECTION ALONG AND NEAR THE MEXICO BORDER. THIS MAY HAVE BEEN AIDED BY AN APPROACHING WAVE NEAR CENTRAL AND SOUTHERN BAJA MEXICO. BOTH THE 00Z GFS AND NAM FORECAST THE WAVE TO MOVE SLOWLY NORTHWARD ACROSS BAJA...NORTHWEST MEXICO...AND ARIZONA TONIGHT AND MONDAY. IN THE PROCESS...THE MODELS DEPICT VARYING AMOUNTS OF UPPER LEVEL DIVERGENCE AHEAD OF THE WAVE AXIS. THIS MAY HELP KEEP PESKY STORM ACTIVITY GOING OVERNIGHT INTO THE MORNING HOURS. THERE ARE ALSO SOME INDICATIONS IN RADAR DATA OF AN MCV ASSOCIATED WITH THE THE SOUTHERN ARIZONA STORM REMNANTS. EARLIER RUNS OF HRRR MODEL FORECAST THE BORDERLAND CONVECTION PRETTY WELL. IT ALSO DID A PRETTY GOOD JOB OF NOT SHOWING WIDESPREAD STORM ACTIVITY OVER THE SOUTH-CENTRAL DESERTS THIS EVENING. THE LATEST RUN IS NOT THAT OPTIMISTIC WITH LATE NIGHT SHOWERS...NOR ARE THE GFS AND NAM...BUT WILL HOLD ON TO SLIGHT CHANCE POPS FOR THE AFOREMENTIONED REASONS. WITH LINGERING CLOUD COVER...OVERNIGHT TEMPS WILL REMAIN WARM AND THUS WILL ALLOW EXCESSIVE HEAT WARNING TO EXPIRE EARLY MONDAY. && .PREVIOUS DISCUSSION ISSUED 255 PM... TONIGHT... AN UNSCHEDULED MORNING YUMA PROVING GROUNDS (YPG) WEATHER BALLOON SOUNDING SHOWED A PLUME OF RELATIVELY HIGH LOW LEVEL MOISTURE MOVING NORTH UP THE COLORADO RIVER. AFTERNOON WATER VAPOR IMAGERY ALSO SHOWED A NOTICEABLE DEGREE OF UPPER LEVEL DIFLUENCE ACROSS SOUTHEAST CA...SOUTHERN NEVADA...AND NORTHWEST MEXICO RELATED TO THE PACIFIC TROF ALONG THE CENTRAL CA COAST. THEREFORE THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS PARTS SOUTHEAST CA AND THE COLORADO RIVER VALLEY THROUGH THIS EVENING. A BROAD BRUSH THREAT FOR SHOWERS AND THUNDERSTORMS WILL CONTINUE ELSEWHERE IN SOUTHWEST AND SOUTH CENTRAL AZ THE REMAINDER OF THE AFTERNOON AND EVENING...WITH A HINT THAT CONVECTIVE ACTIVITY MAY LAST INTO THE NIGHT DUE TO A DISTURBANCE MOVING INTO THE REGION FROM THE BAJA. MONDAY THROUGH FRIDAY... SOME DRYING IS EXPECTED OVER PORTIONS OF SOUTHEAST CA AND THE COLORADO RIVER RELATED TO THE CA TROF MONDAY AND TUESDAY. OTHERWISE THE REMAINDER OF AZ WILL BE UNSEASONABLY WARM AND MARGINALLY MOIST. A THREAT OF AFTERNOON AND EVENING SHOWER AND THUNDERSTORM ACTIVITY WILL CONTINUE THIS WEEK...WITH STORM INTENSITY AND COVERAGE VARYING FROM DAY TO DAY. LITTLE CHANGE IN ATMOSPHERIC HEIGHTS AND THICKNESS VALUES PORTEND A CONTINUATION OF UNSEASONABLY WARM DAYS...WITH DESERT HIGHS POTENTIALLY HITTING THE 110 DEGREE MARK THROUGH THURSDAY. HOWEVER...HIGH TEMPERATURE VARIABILITY WILL OF COURSE RESULT FROM NEARBY CLOUD AND SHOWER DEVELOPMENT. && .AVIATION... SOUTH-CENTRAL ARIZONA...INCLUDING KPHX...KIWA AND KSDL... STORM ACTIVITY OVER THE LOWER DESERTS IS WINDING DOWN THIS EVENING. SPOTTY LIGHT SHOWERS AND ISOLATED THUNDERSTORMS WILL REMAIN A POSSIBILITY DURING THE OVERNIGHT HOURS AS AN UPPER LEVEL WAVE APPROACHES FROM BAJA MEXICO BUT NOT ENOUGH TO PUT PREVAILING SHOWERS OR TEMPO SHWRS IN THE TAFS. SURFACE WINDS WILL BE VARIABLE ACROSS THE METRO AREA OVERNIGHT BEFORE SLOWLY TRENDING TO WESTERLY DIRECTIONS MONDAY AFTERNOON. DEBRIS CLOUDS WILL DECREASE TOWARD MORNING. SOUTHEAST CA AND SOUTHWEST AZ...INCLUDING KIPL AND KBLH... CLOUDINESS WILL INCREASE OVERNIGHT...MAINLY ABOVE 10 KFT MSL...AHEAD OF AN APPROACHING UPPER LEVEL WAVE CURRENTLY NEAR BAJA MEXICO. ISOLATED SHWRS/TSTMS WILL BE POSSIBLE OVER THE REGION BUT PROBABILITY TO LOW TO SHOW PREVAILING OR TEMPO SHWRS/TSTMS IN THE TAFS. SURFACE WINDS WILL FAVOR SOUTHERLY DIRECTIONS THROUGH THE DAY MONDAY. AVIATION DISCUSSION NOT UPDATED FOR AMENDED TAFS. && .FIRE WEATHER... WEDNESDAY THROUGH SUNDAY... THROUGH MIDWEEK...STRONG RIDGING ALOFT OVER THE DESERT SOUTHWEST WILL KEEP TEMPERATURES ABOVE NORMAL...AND MONSOON THUNDERSTORM ACTIVITY CONFINED MAINLY TO THE HIGHER TERRAIN OF SOUTH-CENTRAL ARIZONA WITH ISOLATED THUNDERSTORMS POSSIBLE OVER THE DESERTS OF SOUTH-CENTRAL ARIZONA. A DEEPER MONSOON MOISTURE PROFILE IS EXPECTED TO WORK BACK INTO THE REGION LATER IN THE WEEK AS THE RIDGING WEAKENS AND SOUTHERLY FLOW ALOFT STRENGTHENS...HELPING INCREASE THUNDERSTORM ACTIVITY WHILE ALSO ALLOWING FOR COOLER TEMPERATURES. MINIMUM HUMIDITIES WILL GENERALLY REMAIN IN THE TEENS ACROSS THE LOWER DESERTS...AND IN THE 20-30 PERCENT RANGE ACROSS THE HIGHER TERRAIN...WITH GOOD TO EXCELLENT OVERNIGHT RECOVERIES THROUGH THE PERIOD. WINDS TO REMAIN MAINLY ON THE LIGHT SIDE...WITH THE USUAL DIURNAL TRENDS IN DIRECTION AND SPEED...EXCEPT NEAR THUNDERSTORMS. $$ && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...EXCESSIVE HEAT WARNING ACROSS THE SOUTH CENTRAL DESERTS... AZZ022...AZ023...AZZ027...AZZ028...THROUGH 5 AM MONDAY. CA...NONE. && $$ VISIT US ON FACEBOOK...TWITTER...AND AT WEATHER.GOV/PHOENIX DISCUSSION...AJ PREVIOUS DISCUSSION...VASQUEZ AVIATION...AJ FIRE WEATHER...CB/NOLTE
SOUTHWEST CALIFORNIA AREA FORECAST DISCUSSION...UPDATED
NWS LOS ANGELES/OXNARD CA
1100 PM PDT SUN AUG 18 2013 .SYNOPSIS... A SLIGHT CHANCE FOR THUNDERSTORMS ARE POSSIBLE IN THE SAN GABRIEL MOUNTAINS AND ANTELOPE VALLEY AGAIN TOMORROW...WITH THE UPPER LOW OFF THE CALIFORNIA COAST CONTINUING TO PULL SOME MONSOON MOISTURE INTO THE AREA FROM THE SOUTHEAST. THE UPPER LOW WILL BEGIN TO LIFT NORTHEAST ON THURSDAY...BUT WILL BE REPLACED BY ANOTHER TROUGH OF LOW PRESSURE MOVING IN FROM THE NORTHWEST. THE RESULT WILL BE CONTINUED NEAR OR SLIGHTLY BELOW NORMAL TEMPERATURES AND NIGHT THROUGH MORNING LOW CLOUDS ALONG THE COAST. && .SHORT TERM (TODAY-WED)... A FEW VERY IMPRESSIVE THUNDERSTORMS DEVELOPED ACROSS THE NORTHEAST PORTION OF LOS ANGELES COUNTY THIS AFTERNOON...MAINLY NORTH AND EAST OF PALMDALE TODAY. A COUPLE STORM CELLS WERE RIGHT ON THE LOS ANGELES...SAN BERNARDINO AND KERN COUNTY BORDER. CLOUD TOPS WERE AS HIGH AS 45000 FT WITH VERY IMPRESSIVE RAIN AND HAIL CORES. LATEST NWS RADAR WAS SHOWING MOST OF THE CONVECTIVE ACTIVITY OCCURRING IN THE EASTERN PART OF SAN BERNARDINO COUNTY AND NORTH INTO KERN COUNTY OVER THE LAST HOUR AND LIKELY SETTLING DOWN OVER OUR AREA. MANY PARAMETERS CAME TOGETHER THIS AFTERNOON TO CAUSE THESE EXPLOSIVE THUNDERSTORMS. ALTHOUGH PRECIPITABLE WATERS (PWAT) VALUES WERE NOT THAT IMPRESSIVE AROUND 1.20" AND BEST MID LEVEL MOISTURE WAS ABOVE 600 MB (ABOVE 12000 FT). THE INSTABILITY LOOKED VERY IMPRESSIVE BY MID MORNING AS RAP SOUNDINGS OVER THE MOUNTAINS INDICATED CAPE VALUES WELL OVER 1000 J/KG. SINCE STORMS WERE ABLE TO INITIATE...THEY HAD NO PROBLEM GROWING VERTICALLY. RADAR RETURNS INDICATED VERY HIGH VIL (VERTICAL INTEGRATED LIQUID) AVAILABLE WITH THE STORM WHICH WAS A GOOD REASON WHY THERE WAS NICKEL SIZE HAIL REPORTED IN SOME HIGH DESERT LOCATIONS THIS AFTERNOON. BY LOOKING AT THE WATER VAPOR IMAGERY...IT IS EASY TO SPOT THE DIFFLUENT REGION OVER EASTERN LA COUNTY AND POINTS EAST AND NORTH BASED ON WHERE THE UPPER LOW WAS SITUATED TO HELP LIFT THESE STORMS AND EXPLODE LIKE THEY DID. THERE WAS AN IMPRESSIVE LANDSPOUT SPOTTED NEAR HELENDALE WHICH IS NORTH OF VICTORVILLE IN SAN BERNARDINO COUNTY. AS THE UPPER LOW BEGINS TO PIVOT FARTHER OFFSHORE THIS EVENING...THERE LOOKS TO BE SOME POTENTIAL FOR A FEW NOCTURNAL SHOWERS OVER THE COASTAL WATERS N OF POINT CONCEPTION. I DID ADD SLIGHT CHANCE FOR THUNDERSTORMS FOR AREAS N OF POINT CONCEPTION FROM THE COAST TO SLO INTERIOR VALLEYS AFTER MIDNIGHT THROUGH THE OVERNIGHT HOURS...BUT NOT VERY CONFIDENT. AS FAR AS THE LOWER AND MORE STABLE PART OF THE ATMOSPHERE...(THE MARINE LAYER) WAS AROUND 1000 FT DEEP EARLY THIS EVENING...WHICH IS A BIT DEEPER THEN LAST NIGHT. WITH THE UPPER LOW JUST OFF THE CENTRAL COAST...THERE WILL BE A SLIGHT DEEPENING OF THE MARINE LAYER WHICH WILL ALLOW FOR SOME LOW CLOUDS TO CREEP INTO THE SAN GABRIEL AND POSSIBLY THE SAN FERNANDO VALLEY AFTER MIDNIGHT. TODAY`S HIGH TEMPS WERE OVERALL A TAD LOWER...BUT A FEW INTERIOR AREAS WERE AROUND THE SAME AS YESTERDAY. LONG BEACH WAS MUCH COOLER TODAY AT ONLY 74 COMPARED TO 86 ON SATURDAY DUE TO A PERSISTENT SOUTHERLY FLOW AND LOW CLOUDS HANGING AROUND. FOR MONDAY...NOT MUCH MOVEMENT IS EXPECTED WITH CUTOFF LOW...BUT THERE WILL CONTINUE TO BE SOME MODEST MID LEVEL MOISTURE ADVECTING NORTH OVER EASTERN LA COUNTY AND AREAS TO THE EAST. BOTH THE NAM-WRF AND GFS ARE INDICATING MORE INSTABILITY OVER THE LA COUNTY MOUNTAINS...HAVE ADDED A SLIGHT CHANCE OF THUNDERSTORMS FOR THE EASTERN PORTION OF THE SAN GABRIEL VALLEY AND ANTELOPE VALLEY ONCE AGAIN. THERE WILL BE LESS MOISTURE TO WORK WITH...BUT A SLIGHT CHANCE SEEMS REASONABLE FOR TOMORROW AFTERNOON AND EARLY EVENING. AT THE LEAST EXPECT PARTLY CLOUDY SKIES WITH SOME CUMULUS BUILDUPS IN THE MOUNTAINS AND OVER THE ANTELOPE VALLEY. LOOK FOR A MODEST COOLING TREND FOR TOMORROW AS THE UPPER RIDGE WEAKENS A BIT...ESPECIALLY ACROSS THE NORTHERN PORTION OF THE FORECAST AREA N OF POINT CONCEPTION. THERE WILL LIKELY BE SOME HIGH CLOUDS MOVING TO THE NORTH ACROSS THE SKY...BUT WILL CONTINUE WITH MOSTLY SUNNY SKIES. THE MID SHIFT CAN ADJUST IF NEED BE. ***FROM PREVIOUS DISCUSSION*** VERY LITTLE CHANGE TUE/WED. POSSIBLY SOME HIGH CLOUDS MOVING THROUGH AT TIMES TUESDAY AS MOISTURE WRAPS AROUND THE STILL STATIONARY UPPER LOW. BUT AT THIS TIME NOT SEEING ANYTHING TO WARRANT POPS OR EVEN PARTLY CLOUDY SKIES. DAYTIME HIGHS EXPECTED TO CHANGE LITTLE. .LONG TERM (THU-SUN)...UPPER LOW FINALLY EXITING THE STATE ON THURSDAY TO BE REPLACED BY A WEAK TROF THROUGH THE WEEKEND. THE ECMWF IS DEEPER WITH THE TROF AND THUS COOLER AS WELL. FOR NOW WILL JUST INDICATE LITTLE CHANGE THROUGH THE PERIOD WITH HIGHS NEAR TO SLIGHTLY BELOW SEASONAL NORMS. ALL MODEL SOLUTIONS KEEP MONSOON MOISTURE WELL EAST INTO EARLY NEXT WEEK. && .AVIATION... 19/0600Z. VERY LOW CONFIDENCE FORECAST OVERNIGHT AS A GUST FRONT FROM THE DESERT CONVECTION COULD WREAK HAVOC WITH THE MARINE LAYER. THERE IS A SLIGHT CHC OF TSTMS OVER THE DESERT AND MTNS AS WELL AS ALL OF SLO COUNTY OVERNIGHT. KLAX...LOW CONFIDENCE IN TAF THERE IS A 30 PERCENT CHANCE OF A BRIEF EAST WIND ALONG WITH A TOTAL DISRUPTION OF THE MARINE LAYER. KBUR...LOW CONFIDENCE IN TAF THERE IS A 40 PERCENT CHANCE OF LIFR CIGS 13Z-16Z. && .FIRE... A CUTOFF LOW PRESSURE SYSTEM OFF THE CENTRAL COAST WILL REMAIN NEARLY STATIONARY THROUGH TUESDAY. THIS LOW PRESSURE SYSTEM IS DRAWING SOME MOISTURE INTO SOUTHERN AND CENTRAL CALIFORNIA. AT THE PRESENT TIME...THE MOISTURE AXIS IS FOCUSED ACROSS EASTERN LOS ANGELES COUNTY AND POINTS EASTWARD. THIS INFLUX OF MOISTURE COMBINED WITH AN UNSTABLE AIR MASS WILL CONTINUE TO GENERATE ISOLATED THUNDERSTORMS ACROSS THE EASTERN PORTIONS OF THE SAN GABRIEL MOUNTAINS AND ANTELOPE VALLEY THROUGH THIS EVENING. THESE STORMS WILL HAVE THE POTENTIAL TO PRODUCE STRONG DOWNDRAFT WINDS...HAIL...AND BRIEF HEAVY DOWNPOURS. AROUND THE PERIPHERY OF STORMS...ISOLATED DRY LIGHTNING STRIKES WILL BE POSSIBLE. CLOSER TO THE CLOSED LOW...THERE IS A VERY SLIGHT CHANCE OF STORMS TONIGHT INTO MONDAY FOR AREAS NORTH OF POINT CONCEPTION. THE LOW PRESSURE SYSTEM WILL BRING GUSTY SOUTHERLY WINDS TO INTERIOR SECTIONS THROUGH MONDAY. WITH THE EXCEPTION OF EASTERN LOS ANGELES COUNTY...REMAINING AREAS ARE FORECASTED TO BE QUITE DRY AT LOWER ELEVATIONS. THIS COMBINATION OF GUSTY SOUTHERLY WINDS...LOW HUMIDITIES...VERY WARM TEMPERATURES...AND VERY DRY FUELS WILL CONTINUE TO BRING ELEVATED FIRE DANGER ACROSS INLAND AREAS THROUGH MONDAY. BRIEF CRITICAL FIRE WEATHER CONDITIONS WILL BE LIKELY THROUGH MONDAY ACROSS THE MOUNTAINS. && .LOX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ PUBLIC...KAPLAN/MW FIRE...GOMBERG AVIATION...ASR SYNOPSIS...SUKUP WWW.WEATHER.GOV/LOSANGELES
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
424 AM EDT MON AUG 19 2013 .SYNOPSIS... A STATIONARY FRONT OVER THE AREA WILL DISSIPATE AS HIGH PRESSURE BUILDS WEST ACROSS THE AREA MID TO LATE WEEK. A WEAK TROUGH OF LOW PRESSURE WILL APPROACH FROM THE NORTHWEST THIS WEEKEND...FOLLOWED BY HIGH PRESSURE INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... PRE-DAWN...A MOIST AND RELATIVELY UNSTABLE AIR MASS ACROSS THE REGION EARLY THIS MORNING...QUITE TYPICAL FOR THE SEASON. THROUGH DAWN...MOST AREAS SHOULD REMAIN DRY WITH A FEW SHOWERS POSSIBLE NEAR/ALONG THE COAST AND ADJACENT TO THE CSRA AREA PRIOR TO DAYBREAK. TEMPS AND DEW POINTS IN THE MID 70S MOST AREAS. SOUTHEAST GEORGIA AND SOUTHERN SOUTH CAROLINA WILL REMAIN IN THE NW FLANKS OF THE ATLC SUBTROPICAL RIDGE TODAY. THE DEPARTING UPPER TROUGH FROM THE OHIO VALLEY TO THE MID SOUTH REGION IS PROGGED TO LIFT OUT TO THE NE INTO NEW ENGLAND BY LATE DAY. THE TAIL OF THE MID LEVEL VORT WILL INDUCE SOME VERY WEAK HEIGHT FALLS OVER THE INLAND CAROLINAS TODAY WHILE DEEP MID SUMMER MOISTURE PERSISTS REGION-WIDE. THE OLD WEDGE FRONT CONTINUES TO DECAY OVER THE CAROLINAS TODAY. FORECAST SOUNDINGS AND 00Z MODEL PROGS INDICATE POTENTIAL FOR SCATTERED CONVECTIVE RAINS TO DEVELOP OVER THE EASTERN THIRD OF THE AREA BY MID MORNING ONCE THE LAND MASS BEGINS TO QUICKLY WARM AND ESPECIALLY SINCE SATELLITE IMAGERY SHOWS STRONG POTENTIAL FOR DIFFERENTIAL HEATING WITH I-95 THE DIVIDING LINE. CHANCE POPS ARE EXPECTED TO SPREAD INLAND THIS AFTERNOON WITH MANY AREAS ALONG AND W OF U.S. 17 EXPECTED TO SEE SCATTERED SHOWERS AND TSTMS. SOME OF OUR INLAND AREAS COULD SEE SOME VERY HEAVY DOWNPOURS IN DEEP CONVECTION THIS AFTERNOON. THE LATEST 3KM RAP MODEL INDICATES A PRETTY COMPLEX MESOSCALE AND THUS EXPECT SOME LOCALLY HEAVY CONVECTIVE RAINS WILL DEVELOP N OF I-16 AND INLAND FROM U.S. 17 WHERE THE SUBTLE MID LEVEL HEIGHT FALLS OCCUR. WE WILL HIGHLIGHT A RISK FOR LOCALLY HEAVY DOWNPOURS AND MINOR TEMPORARY FLOODING CONCERNS FOR OUR NW INLAND ZONES IN OUR HAZARDOUS WEATHER OUTLOOK. THIS IS MAINLY IN RESPECT TO THE SOGGY SOIL CONDITIONS AND ONGOING RIVER FLOODING PLUS SWOLLEN TIDAL CREEKS WITH THE FULL MOON CYCLE. WE RAISED HIGH TEMPS A DEGREE OR SO IN SOME AREAS AS GUIDANCE IS RUNNING TOO COOL NOW THE WEDGE TO GONE. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... TUESDAY THROUGH THURSDAY...A TYPICAL SUMMERTIME PATTERN WILL EVOLVE OVER THE SOUTHEASTERN UNITED STATES AS ATLANTIC HIGH PRESSURE EXPANDS OVER THE AREA THROUGH MIDWEEK. AS THIS OCCURS...DEEPEST MOISTURE WILL SHIFT INLAND AND WILL BE THE MAIN SOURCE OF PRECIP ACTIVITY EACH AFTERNOON WHILE WEAK H5 SHORTWAVES PASS OVERHEAD. DESPITE THE INLAND SHIFT OF DEEPEST MOISTURE...LIGHT ONSHORE FLOW WILL SUPPORT PWATS BETWEEN 1.5 TO 2 INCHES AS WELL AS SCATTERED SHOWERS AND/OR THUNDERSTORMS OVER SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA. HOWEVER...EXPECT MOST SHOWERS/THUNDERSTORMS TO GRADUALLY SHIFT INLAND BY EARLY AFTERNOON EACH DAY ALONG OR AHEAD A SEABREEZE. OVERALL HIGH TEMPS SHOULD RANGE IN THE UPPER 80S TO AROUND 90 EACH AFTERNOON. OVERNIGHT LOWS WILL RANGE IN THE LOW 70S INLAND TO MID/UPPER 70S ALONG THE COAST. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... A TYPICAL SUMMERTIME PATTERN WILL PERSIST THROUGH LATE WEEK AS ATLANTIC HIGH PRESSURE REMAINS OVER THE SOUTHEAST. CONDITIONS SHOULD REMAIN SOMEWHAT DRYER THROUGH FRIDAY WITH WEST/SOUTHWEST FLOW ALOFT. HIGH PRESSURE WILL THEN GRADUALLY RETREAT SOUTH AND EAST INTO THE WEEKEND AS A WEAK TROUGH OF LOW PRESSURE APPROACHES FROM THE NORTHWEST. A SLIGHT CHANCE OF SHOWERS AND/OR THUNDERSTORMS WILL BE POSSIBLE EACH DAY...WITH POSSIBLY INCREASING CHANCES ON SUNDAY BEFORE SFC HIGH PRESSURE AND DRYER MID LVL AIR SHIFTS OVER THE SOUTHEAST INTO EARLY NEXT WEEK. OVERALL HIGH TEMPS SHOULD RANGE IN THE UPPER 80S TO LOWER 90S EACH AFTERNOON...HIGHEST OVER INLAND AREAS IN SOUTHEAST GEORGIA. OVERNIGHT LOW TEMPS SHOULD RANGE IN THE LOW 70S INLAND TO LOW/MID 70S ALONG THE COAST. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... A MAINLY VFR FORECAST THIS TAF CYCLE AT THE KCHS/KSAV TERMINALS WITH POTENTIAL FOR BRIEF MVFR CIGS JUST AFTER SUNRISE AS THE LAND HEATS AND CUMULUS FIELDS DEVELOP. SCATTERED SHOWERS DEVELOPING THIS MORNING IN THE COASTAL CORRIDOR PER LATEST MODEL OUTPUT... PUSHING INLAND THIS AFTERNOON. IF DEEPER CONVECTION DEVELOPS IT COULD SLIDE BACK INTO THE THE TAF CORRIDOR AFTER MID AFTERNOON AS STEERING FAVORS A SW-NE TRAJECTORY. VCSH THE BEST WE DO FOR NOW...SIMILAR TO THE LAST PACKAGE. EXTENDED AVIATION OUTLOOK...VFR CONDITIONS ARE EXPECTED TO PREVAIL TUESDAY THROUGH SATURDAY AS HIGH PRESSURE PERSISTS OVER THE SOUTHEAST. BRIEF MVFR CIGS/VSBYS ARE POSSIBLE EACH AFTERNOON WITH INLAND MOVING SHOWERS AND/OR THUNDERSTORMS. && .MARINE... ATLC HIGH PRES WILL BE THE MAIN PLAYER FOR THE WATERS. MAINLY A LIGHT SE TO SSE FLOW THROUGH TONIGHT WITH SEAS 2 TO 3 FT. TUESDAY THROUGH FRIDAY...WINDS/SEAS ARE EXPECTED TO REMAIN WELL BELOW SMALL CRAFT ADVISORY LEVELS THROUGH LATE WEEK WITH HIGH PRESSURE DOMINATING THE WATERS. IN GENERAL...SOUTH TO SOUTHEAST WINDS WILL REMAIN AT OR BELOW 10-12 KT...HIGHEST NEAR SEABREEZE CIRCULATIONS ALONG THE COAST. SEAS WILL REMAIN AT OR BELOW 3 FT...HIGHEST IN OUTER GEORGIA WATERS. WATERSPOUTS...IT IS LOOKING DECENT THIS MORNING GIVEN INSTABILITY AND LIGHT CHAOTIC WIND FIELDS. WILL BE WAITING FOR SUNRISE TO SPOT CU LINES AND LAND BREEZE BOUNDARIES BEFORE ISSUING ANY MARINE WEATHER STATEMENTS. RIP CURRENTS...A SLIGHT INCREASE IN SWELLS COULD LEAD TO A MODERATE RISK OF RIPS BY MID WEEK. LOW RISK AT AREA BEACHES TODAY. && .TIDES/COASTAL FLOODING... GIVEN THE PERIGEAN SPRING TIDES...ADDITIONAL COASTAL FLOOD ADVISORIES ARE POSSIBLE THROUGH MID-WEEK WITH THE EVENING HIGH TIDE CYCLE. THIS EVENINGS HIGH TIDE SHORTLY BEFORE SUNSET COULD PRODUCE SHALLOW COASTAL FLOODING IN DOWNTOWN CHARLESTON AND FORT PULASKI ONCE AGAIN. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM... SHORT TERM...DPB LONG TERM...DPB AVIATION... MARINE...DPB TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
149 AM EDT MON AUG 19 2013 .UPDATE... /ISSUED AT 940 PM EDT SUN AUG 18 2013/ HAVE ADJUSTED POPS FOR A FEW HOURS BASED ON RADAR. SCATTERED CONVECTION STILL MOSTLY ACROSS CENTRAL ZONES. WEDGE STILL HOLDING JUST ABOUT ATLANTA TO ATHENS AND MAY NOT MUCH MUCH MORE OVERNIGHT. WILL KEEP THE FLASH FLOOD WATCH UNTIL EXPIRATION. 41 .PREVIOUS... /ISSUED AT 250 PM EDT SUN AUG 18 2013/ .SHORT TERM /TONIGHT THROUGH MONDAY/... PRIMARY CONCERNS FOR THE SHORT TERM PERIOD WILL BE WHERE MODERATE TO HEAVY RAIN AXIS SETS UP AND WHAT NEEDS TO BE DONE WITH THE FLASH FLOOD WATCH AS A RESULT. AFTER A WET START TO THE DAY...ACTIVITY HAS DWINDLED FOR THE MOST PART WITH JUST SOME PASSING SHOWERS THROUGH THE ATLANTA METRO NOW HEADING INTO NORTHEAST GEORGIA. FOCUS NOW SHIFTS TO THE SOUTHEAST WHERE LOCAL WRF AND HRRR HAVE BEEN BEEN HONING IN ON WITH THUNDERSTORMS DEVELOPING NICELY OVER THE FAR SOUTHEAST AT THIS HOUR. SPC SREF SHOWS INSTABILITY INCREASING AS WARM FRONT EASES NORTHWARD WITH AREAS AROUND TOOMBS AND MONTGOMERY COUNTIES SHOWING IN EXCESS OF 1000 J/KG OF AVAILABLE CAPE. WOULD EXPECT A LINE OF SHOWERS AND STORMS TO DEVELOP IN THIS AREA AND PROGRESS TOWARD MACON LATER THIS AFTERNOON INTO THE EVENING. ADDITIONAL ACTIVITY COULD FORM AHEAD OF THIS AS WELL IN THE MORE UNSTABLE SECTION FROM COLUMBUS TO JUST SOUTH OF ATHENS. ALSO WATCHING GULF INITIATED STORMS AS THESE LOOK TO AFFECT THE SOUTH AS WELL TONIGHT WITH STORMS ALREADY PUSHING INTO THE GEORGIA PORTION FROM THE FLORIDA PANHANDLE. THERE IS SOME DISPARITY IN SHORT TERM MODELS ON HOW THIS WILL EVENTUALLY EVOLVE THIS EVENING WITH NAM12 INDICATING MORE DEVELOPMENT ON THE WESTERN SIDE OF THE AREA VERSUS THE SOUTH. THIS UNCERTAINTY IS PROBLEMATIC GIVEN THE FLOOD WATCH ORIENTATION WHICH IS CURRENTLY OVER THE WEST. IF CURRENT TRENDS HOLD HOWEVER...THE SOUTHERN SECTIONS WOULD BE MORE UNDER THE GUN. WITH THE UNCERTAINTY INVOLVED...WILL LET THE EVENING SHIFT TAKE ANOTHER LOOK AT THIS DEVELOPING EVENT TO SEE IF FLOOD WATCH NEEDS TO CONTINUE AND FOR WHAT AREAS. FOR MONDAY...PRETTY MUCH THE SAME PATTERN BUT WITH WEDGE CONTINUING TO WEAKEN AND MORE MOISTURE AVAILABLE FOR THE NORTHERN ZONES AS WELL AS INSTABILITY. WENT LIKELY FOR MOST AREAS...FAVORING THE SOUTH ONCE AGAIN...CLOSER TO THE VICINITY OF STALLED OUT BOUNDARY. STILL USED SOME SLIGHT CAD INFLUENCES FOR THE HIGH TEMPS MONDAY BUT SHOULD WARM NICELY TO UPPER 70S NORTH TO LOWER 80S SOUTH. DEESE .LONG TERM /MONDAY NIGHT THROUGH SUNDAY/... /ISSUED AT 250 PM EDT SUN AUG 18 2013/ BUMPED POPS UP SOME INTO THURSDAY TO ACCOUNT FOR THE VERY MOIST AIRMASS OVER THE AREA. OTHERWISE NO MAJOR CHANGES. BDL PREVIOUS DISCUSSION... THE WET PATTERN CONTINUES INTO THE EXTENDED. THE STATIONARY FRONT OVER SOUTH GA TODAY WILL MOVE SLOWLY NORTHWARD THROUGH MONDAY AND SHOULD BE SOME WHERE BETWEEN ATL AND MCN BY TUE MORNING. THIS FRONT WILL WEAKEN SOME BUT IT WILL STILL ACT AS A GUIDE FOR GULF MOISTURE TO MOVE NORTHWARD ACROSS THE REGION THROUGH THE MIDDLE OF THE WEEK. THE WEDGE LOOKS TO FINALLY BREAK DOWN SOMETIME MONDAY WHICH WILL ALSO ALLOW FOR A MORE DIURNALLY DRIVEN PRECIP PATTERN THROUGH DAY 7. BEST TIMING FOR THE HEAVIEST RAIN WILL BE IN THE SHORT TERM BUT DEEP TROPICAL MOISTURE REMAINS OVER THE REGION THROUGH WED/THU WITH PRECIPITABLE WATERS IN THE 1.5 TO 2.0 INCH RANGE THROUGH THU. THE DEEPER MOISTURE MOVES NORTH AND EAST OF THE STATE BY THU NIGHT BUT THE DIURNAL CONVECTIVE TREND WILL CONTINUE INTO NEXT WEEKEND. TEMPS WILL BEGIN TO REBOUND BY TUE AND BE BACK TO NEAR SEASONAL NORMS BY THU/FRI. 01 && .AVIATION... 06Z UPDATE... FRONTAL BOUNDARY JUST SOUTH OF ATL SHOULD REMAIN THERE TONIGHT... THEN DRIFT NORTH OF ATL MON AFTERNOON. LIGHT EAST WINDS WILL PERSIST TONIGHT...THEN BECOME MORE SE BY MON AFTERNOON AT 7-9KTS. EXPECT IFR/LIFR CIGS TO PREVAIL AGAIN TONIGHT WITH -DZ/BR RESTRICTING VSBY DOWN TO 1-3SM AT TIMES. CIGS GRADUALLY IMPROVE TO MVFR BY 15Z...THEN POSSIBLY LOW VFR LEVELS BY 17-19Z MON AS THE WARM FRONT DRIFTS NORTH. MODELS SHOW SCT -SHRA/-TSRA AROUND BY MON AFTERNOON SO WILL INCLUDE A PROB30 -TSRA 20-24Z MON AS ATL GETS IN THE WARM SECTOR. //ATL CONFIDENCE...06Z UPDATE... MEDIUM ON ALL ELEMENTS 39 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 69 81 69 79 / 50 60 50 70 ATLANTA 69 79 70 79 / 70 50 40 60 BLAIRSVILLE 65 76 66 78 / 70 50 50 60 CARTERSVILLE 69 79 69 78 / 70 50 50 60 COLUMBUS 71 83 72 85 / 50 60 40 70 GAINESVILLE 68 78 69 76 / 70 50 50 70 MACON 70 82 70 82 / 40 60 40 60 ROME 69 80 70 80 / 70 50 50 60 PEACHTREE CITY 70 80 71 79 / 60 50 40 60 VIDALIA 72 86 72 86 / 40 60 40 40 && .FFC WATCHES/WARNINGS/ADVISORIES... FLASH FLOOD WATCH UNTIL 8 PM EDT THIS EVENING FOR THE FOLLOWING ZONES: BARTOW...BIBB...BLECKLEY...BUTTS...CARROLL...CATOOSA... CHATTAHOOCHEE...CHATTOOGA...CHEROKEE...CLAYTON...COBB...COWETA... CRAWFORD...CRISP...DADE...DEKALB...DODGE...DOOLY...DOUGLAS... FANNIN...FAYETTE...FLOYD...GILMER...GORDON...HARALSON...HARRIS... HEARD...HENRY...HOUSTON...LAMAR...MACON...MARION...MERIWETHER... MONROE...MURRAY...MUSCOGEE...NORTH FULTON...PAULDING...PEACH... PICKENS...PIKE...POLK...PULASKI...ROCKDALE...SCHLEY...SOUTH FULTON...SPALDING...STEWART...SUMTER...TALBOT...TAYLOR... TELFAIR...TROUP...TWIGGS...UPSON...WALKER...WEBSTER... WHITFIELD...WILCOX. && $$ SHORT TERM...DEESE LONG TERM....BDL AVIATION...39
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
535 AM EDT Mon Aug 19 2013 ...Forecast Update... Issued at 530 AM EDT Mon Aug 19 2013 Updated the forecast to remove areas of fog with patchy dense fog from southeast Indiana and the Bluegrass region of KY. Mid level clouds and lesser low level moisture than central and southern KY (where patches of dense fog have been reported) have limited fog formation over southeast Indiana and the Bluegrass. Downgraded this area to just patchy fog for the rest of the pre-dawn hours. Issued an SPS for portions of south and central KY where patchy dense fog has been reported and where it rained yesterday (which should be fog prone). Few-sct mid level clouds continue to move over this area improving fog at times so feel dense fog coverage will remain patchy. .SHORT TERM (Now through Tuesday)... Issued at 330 AM EDT Mon Aug 19 2013 The main forecast concern in the short term will be fog this morning. A very moist low level atmosphere along with very light or nearly calm winds have created an ideal environment for fog formation which we`ve already seen develop in our area. The worst fog spots remain over southern IL/western KY and over southwest Ohio. The 5Z RAP model has these fog areas handled well and expect them to expand into central KY and portions of southeast IN. Low clouds will also accompany the fog as soundings indicate a shallow layer of trapped moisture under a weak inversion. With these thoughts in mind, think that most locations over southern IN and central KY will see areas of fog this morning. Some locations over central KY and southeast IN will probably see patches of dense fog as well assuming the low clouds don`t inhibit fog density too much. Will highlight the patchy dense fog in the HWO this morning and monitor closely in case it becomes more widespread and an SPS or dense fog advisory is need. For the rest of the day, fog should burn off fairly quickly after sunrise. With an upper trough passing through the region, can`t rule out an isld shower over portions of south and east central KY. However, did scale the area of potential precip back a bit. High temperatures should reach the low to mid 80s this afternoon. Tonight a second upper trough will settle into the mid Mississippi River Valley. Some fog may be possible but not as widespread as this morning. Will continue inherited patchy fog mainly in river valleys. Lows tonight will be in the mid 60s. For Tues, expect a 20% chance of showers/t-storms to expand from south to north over the area throughout the day as a vort wave on the eastern side of the upper trough push north through our area. Any convection would be on the weak side. Tuesday afternoon high temps should be in the low to mid 80s with southern Indiana being the hottest due to a longer period of sunshine before clouds/isld convection move in. .LONG TERM (Tuesday Night through Sunday)... Issued at 311 AM EDT Mon Aug 19 2013 The models have finally come into agreement with a mid-level low that forms over the Ohio Valley at the start of this forecast period. This cutoff low hangs out in the region through Thursday night when it undergoes a transformation into an open wave in response to an approaching shortwave. This shortwave rides around the periphery of a stout ridge building in over the Plains and looks to exit the forecast area by early Saturday. The ridge continues to build in from the west, giving us dry conditions through the end of the weekend and into early next week. Tuesday night through Thursday: For this issuance, have introduced slight chance PoPs for Tuesday night as the low establishes itself overhead and surface southerly flow allows for moisture to be pulled in. Chance PoPs continues for Wednesday as daytime heating assists in convection across the area. With the loss of daytime heating and in conjunction with general model consensus, have kept PoPs out overnight Wednesday into early Thursday. As the low is depicted to begin traversing eastward Thursday, have only slight chance during the day with the primary focus for possible convection more toward eastern KY. The models have the low slowly but surely progressing eastward during this time frame and am a little skeptical on its speed. How quickly the low exits will depend on the timing of a weak frontal boundary attempting to lay out across the southern Great Lakes by Thursday night. Thursday night through Friday night: Have gone with slight chance PoPs strictly across the northern sections as the alluded to frontal boundary approaches from the north. The front stalls well to our north and does not currently appear to be a factor for us beyond Friday. The aforementioned shortwave swings around the region Friday, hence the slight to chance PoPs under diurnally-driven conditions. Again, skepticism sets in for the timing of it all as it seems to really move through a little too quickly. For now, have kept the area dry Friday night until a better handle on the progression of everything plays out. Temperatures will be more difficult to predict Tuesday night through Friday night as cloudy skies and/or rain will obviously wreck havoc. What can be said with confidence is that highs will continue to run slightly below normal and lows will flirt with normal. Saturday through Sunday: With that ridge building in, we`ll begin to see real signs of summer return as temperatures look to rebound back toward normal and partly to mostly sunny skies prevail. && .AVIATION (06Z TAF Update)... Issued at 125 AM EDT Mon Aug 19 2013 The TAF challenge this morning will be the extent and intensity of fog and low cigs over the TAF sites as we sit in a very moist environment with weak or calm winds. Observations across the region reveal 2 areas of fog/low cigs...one over Illinois/western KY and the other over southwest Ohio. The RAP is picking up on these areas of fog/low cigs well and forecasts that they will expand into SDF/BWG/LEX as the morning progresses. LEX seems to be the most likely to see the worst flight conditions with MVFR conditions likely to develop within the next few hours and decline to LIFR by around 9 or 10Z. BWG/SDF seem to be more on the edges of the projected fog/low cigs. Since BWG is very fog prone, did go ahead and bring flight conditions into the LIFR cat by 9Z with a slightly slower progression to that restriction than LEX. SDF seems to be the least likely to see really low vsbys/cigs although based on the latest RAP guidance, they will probably drop into the IFR cat just before sunrise. If the fog/low cigs expand more than projected by the RAP, SDF TAF will need to be amended with more flight restrictions. Fog/low cigs should improve by 13 or 14Z with VFR conditions expected the rest of the day with a light ENE wind. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Update.........AMS Short Term.....AMS Long Term......lg Aviation.......AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
333 AM EDT Mon Aug 19 2013 .SHORT TERM (Now through Tuesday)... Issued at 330 AM EDT Mon Aug 19 2013 The main forecast concern in the short term will be fog this morning. A very moist low level atmosphere along with very light or nearly calm winds have created an ideal environment for fog formation which we`ve already seen develop in our area. The worst fog spots remain over southern IL/western KY and over southwest Ohio. The 5Z RAP model has these fog areas handled well and expect them to expand into central KY and portions of southeast IN. Low clouds will also accompany the fog as soundings indicate a shallow layer of trapped moisture under a weak inversion. With these thoughts in mind, think that most locations over southern IN and central KY will see areas of fog this morning. Some locations over central KY and southeast IN will probably see patches of dense fog as well assuming the low clouds don`t inhibit fog density too much. Will highlight the patchy dense fog in the HWO this morning and monitor closely in case it becomes more widespread and an SPS or dense fog advisory is need. For the rest of the day, fog should burn off fairly quickly after sunrise. With an upper trough passing through the region, can`t rule out an isld shower over portions of south and east central KY. However, did scale the area of potential precip back a bit. High temperatures should reach the low to mid 80s this afternoon. Tonight a second upper trough will settle into the mid Mississippi River Valley. Some fog may be possible but not as widespread as this morning. Will continue inherited patchy fog mainly in river valleys. Lows tonight will be in the mid 60s. For Tues, expect a 20% chance of showers/t-storms to expand from south to north over the area throughout the day as a vort wave on the eastern side of the upper trough push north through our area. Any convection would be on the weak side. Tuesday afternoon high temps should be in the low to mid 80s with southern Indiana being the hottest due to a longer period of sunshine before clouds/isld convection move in. .LONG TERM (Tuesday Night through Sunday)... Issued at 311 AM EDT Mon Aug 19 2013 The models have finally come into agreement with a mid-level low that forms over the Ohio Valley at the start of this forecast period. This cutoff low hangs out in the region through Thursday night when it undergoes a transformation into an open wave in response to an approaching shortwave. This shortwave rides around the periphery of a stout ridge building in over the Plains and looks to exit the forecast area by early Saturday. The ridge continues to build in from the west, giving us dry conditions through the end of the weekend and into early next week. Tuesday night through Thursday: For this issuance, have introduced slight chance PoPs for Tuesday night as the low establishes itself overhead and surface southerly flow allows for moisture to be pulled in. Chance PoPs continues for Wednesday as daytime heating assists in convection across the area. With the loss of daytime heating and in conjunction with general model consensus, have kept PoPs out overnight Wednesday into early Thursday. As the low is depicted to begin traversing eastward Thursday, have only slight chance during the day with the primary focus for possible convection more toward eastern KY. The models have the low slowly but surely progressing eastward during this time frame and am a little skeptical on its speed. How quickly the low exits will depend on the timing of a weak frontal boundary attempting to lay out across the southern Great Lakes by Thursday night. Thursday night through Friday night: Have gone with slight chance PoPs strictly across the northern sections as the alluded to frontal boundary approaches from the north. The front stalls well to our north and does not currently appear to be a factor for us beyond Friday. The aforementioned shortwave swings around the region Friday, hence the slight to chance PoPs under diurnally-driven conditions. Again, skepticism sets in for the timing of it all as it seems to really move through a little too quickly. For now, have kept the area dry Friday night until a better handle on the progression of everything plays out. Temperatures will be more difficult to predict Tuesday night through Friday night as cloudy skies and/or rain will obviously wreck havoc. What can be said with confidence is that highs will continue to run slightly below normal and lows will flirt with normal. Saturday through Sunday: With that ridge building in, we`ll begin to see real signs of summer return as temperatures look to rebound back toward normal and partly to mostly sunny skies prevail. && .AVIATION (06Z TAF Update)... Issued at 125 AM EDT Mon Aug 19 2013 The TAF challenge this morning will be the extent and intensity of fog and low cigs over the TAF sites as we sit in a very moist environment with weak or calm winds. Observations across the region reveal 2 areas of fog/low cigs...one over Illinois/western KY and the other over southwest Ohio. The RAP is picking up on these areas of fog/low cigs well and forecasts that they will expand into SDF/BWG/LEX as the morning progresses. LEX seems to be the most likely to see the worst flight conditions with MVFR conditions likely to develop within the next few hours and decline to LIFR by around 9 or 10Z. BWG/SDF seem to be more on the edges of the projected fog/low cigs. Since BWG is very fog prone, did go ahead and bring flight conditions into the LIFR cat by 9Z with a slightly slower progression to that restriction than LEX. SDF seems to be the least likely to see really low vsbys/cigs although based on the latest RAP guidance, they will probably drop into the IFR cat just before sunrise. If the fog/low cigs expand more than projected by the RAP, SDF TAF will need to be amended with more flight restrictions. Fog/low cigs should improve by 13 or 14Z with VFR conditions expected the rest of the day with a light ENE wind. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Short Term........AMS Long Term.........lg Aviation..........AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
152 AM EDT Mon Aug 19 2013 ...Forecast Update... Issued at 145 AM EDT Mon Aug 19 2013 Updated to remove isld POPs over south and east central KY. Looks like the stream of moisture/forcing for those light precip chances has moved mostly to our east. The main forecast challenge for this morning will be fog and low clouds. The latest RAP model has the best handle on fog/low cloud areas developing over southern IL/western KY and southwest OH this morning. It projects those areas will expand into much of central KY and southeast IN. Current forecast handles the areal extent of fog well, but a mention of patchy dense fog may be needed with the 4am forecast package. Low clouds would be the main inhibitor of dense fog but even so, the model indicates visibilities should drop below a half mile. For now will hold off on a dense fog mention, and watch fog/low cloud development over the next few hours. Issued at 1140 PM EDT Sun Aug 18 2013 One more update to bump up coverage of fog some. Seeing visibilities drop in a few spots late this evening. The clear spot to our west has seen PAH drop down to a quarter mile in its latest ob. Will have to watch for worse visibilities over our area tonight, but for now the trend looks good. Still cannot rule out a stray shower developing, as the upper trough axis still has not passed our region. Have left in a slight chance across the southeast for a few more hours tonight. Issued at 625 PM EDT Sun Aug 18 2013 Active convection appears confined to a line running from north of Hartford to west of Lawrenceburg in KY. Fine tuned the rain chances to focus on this region next couple of hours. Still expect activity to quiet down with loss of heating and as the upper low, which has been near us for days, weakens and accelerates northeast. Next issue will be the chance for fog. Statistical guidance hints at visibilities lowering during the night, and this makes sense with residual moisture. Cloud cover should keep us from going too dense however. For now have added in patchy fog everywhere after midnight. .SHORT TERM (Now through Monday Night)... Issued at 300 PM EDT Sun Aug 18 2013 The cutoff upper low that was centered over the Mississippi and Ohio River confluence this morning is filling, becoming an open wave, and meandering eastward, as another shortwave trough begins to dive southeast into the upper Mississippi Valley. Scattered showers and isolated storms will be possible through the afternoon and early evening hours, as heating combines with large-scale ascent. The mid-level trough axis will swing across the area tonight, combined with loss of heating, will put an end to convection. So, will have scattered precipitation tapering off from west to east through the evening hours, with a dry forecast from about midnight onward. Will continue with dry conditions through Monday morning. However, the trough across the upper Mississippi Valley tonight will spread across the Ohio Valley by Monday afternoon. Appears some low-level moisture will remain in place and with afternoon heating, could spark some convection. Soundings indicate there should be slight capping across much of the CWA, allowing mainly low-topped showers to develop. By late in the afternoon the cap could weaken just enough to squeeze out an isolated thunderstorm or two, but that chance appears minimal. So, will run with isolated showers in the forecast through the afternoon and early evening hours Monday. This will generally be along and southeast of a line from Frankfort southwestward to Bowling Green. Any activity will dissipate with loss of heating, leaving the overnight hours dry. Temperatures will drop into the lower 60s tonight, with a few breaks in the cloud cover. Highs in the low to middle 80s will be common Monday under partly cloudy skies. Expect lows in the low and middle 60s Monday night under partly cloudy to mostly clear skies. Cannot rule out some patchy fog tonight and Monday night, but tonight will depend on how much cloud cover is lost and Monday night will depend on how much drying occurs through Monday afternoon. .LONG TERM (Tuesday through Sunday)... Issued at 300 PM EDT Sun Aug 18 2013 The long term period continues to look rather unsettled for much of the upcoming work week as the Ohio Valley will remain in a rather stagnant upper level pattern. However, the overall pattern looks to improve a bit by the end of the week and into the weekend as the latest forecast datasets point to upper level ridging building in from the west which will result in warmer and more seasonal temperatures for the region. Until late week, the upper level flow is forecast to remain rather blocky and complex as the band of westerlies remains holed up along the US/Canadian border. Overall, there is not much forcing in the hemispheric flow to kick things into gear and smooth the wave pattern out. With that said, the model solutions show that a bagging long wave trough axis will remain over the eastern part of the US from Tuesday through at least late Thursday. With the trough axis overhead, diurnally driven convection will be possible across the region. While the overall coverage for the week looks to be isolated to scattered, it does appear that the best chances for rainfall would be Wednesday as the actual trough pulls through the region. With this forecast we plan on keeping isolated-scattered PoPs in the forecast each afternoon for Tuesday-Thursday with the highest chances Wednesday. With regards to convection strength, the combination of weak flow aloft and rather modest instability suggests that severe weather is not likely. However, high atmospheric moisture content combined with the weak steering flow could lead to heavy rain production with any storm that develops. Temperatures through the period will remain below normal. Have sided again with the consensus raw datasets for max/min temperatures as they have verified well over the last few days. This actually results in a cooling trend applied for Tuesday/Wednesday due to expected clouds and precipitation. Tues/Wed highs will average in the lower 80s across the central/east/southeast with lower-middle 80s across the northwest/west sections. With the upper trough passing to our east on Thursday, we expect less clouds and precipitation which should allow temperatures to warm into the middle 80s. Overnight lows will be rather mild with readings in the upper 60s to the lower 70s. By Friday, the model solutions start to show their normal spread. The GFS solutions suggest a weak cold front will pass through the region and then stall out to our south. On the other hand, the Euro solution is not as progressive and allow the upper ridging to build in which would keep the frontal boundary up to our north. For now have, opted to keep the forecast on the dry side, but will continue to monitor later forecasts to see if PoPs will be required. With the upper ridge building in, Sat/Sun continue to look dry at this point. Temperatures should continue to moderate through the period with afternoon highs in the middle to upper 80s with overnight lows in the upper 60s to the lower 70s. && .AVIATION (06Z TAF Update)... Issued at 125 AM EDT Mon Aug 19 2013 The TAF challenge this morning will be the extent and intensity of fog and low cigs over the TAF sites as we sit in a very moist environment with weak or calm winds. Observations across the region reveal 2 areas of fog/low cigs...one over Illinois/western KY and the other over southwest Ohio. The RAP is picking up on these areas of fog/low cigs well and forecasts that they will expand into SDF/BWG/LEX as the morning progresses. LEX seems to be the most likely to see the worst flight conditions with MVFR conditions likely to develop within the next few hours and decline to LIFR by around 9 or 10Z. BWG/SDF seem to be more on the edges of the projected fog/low cigs. Since BWG is very fog prone, did go ahead and bring flight conditions into the LIFR cat by 9Z with a slightly slower progression to that restriction than LEX. SDF seems to be the least likely to see really low vsbys/cigs although based on the latest RAP guidance, they will probably drop into the IFR cat just before sunrise. If the fog/low cigs expand more than projected by the RAP, SDF TAF will need to be amended with more flight restrictions. Fog/low cigs should improve by 13 or 14Z with VFR conditions expected the rest of the day with a light ENE wind. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Update.........AMS/RJS Short Term.....MJP Long Term......MJ Aviation.......AMS
AREA FORECAST DISCUSSION
NWS JACKSON KY
137 AM EDT MON AUG 19 2013 .UPDATE... ISSUED AT 137 AM EDT MON AUG 19 2013 FORECAST PRETTY MUCH ON TRACK SO FAR TONIGHT. A LINE OF RAIN SHOWERS CURRENTLY MOVING UP THE VIRGINIA AND WEST VIRGINIA BORDERS TONIGHT ARE CONTINUING TO SPREAD EVER SO SLOWLY WESTWARD INTO FAR EASTERN KENTUCKY. THIS EVOLUTION IS EXPECTED TO CONTINUE OVERNIGHT AND DURING THE DAY ON MONDAY PER THE LATEST MODEL DATA. THEREFORE...NO MAJOR UPDATE WAS MADE TO THE FORECAST. UPDATE ISSUED AT 942 PM EDT SUN AUG 18 2013 THE WIDELY SCATTERED SHOWERS AFFECTING THE AREA DURING THE EVENING HAVE DECREASED IN COVERAGE AT THIS TIME ON THIS SIDE OF THE KY/VA BORDER. TO THE EAST OF THE BORDER...A BAND OF SHOWERS CONTINUES TO ADVANCE NORTHEASTWARD. THESE SHOWERS WILL SKIRT OUR VA BORDER COUNTIES THROUGH THE NIGHT INTO TOMORROW MORNING AND WILL MAINTAIN HIGHEST POPS IN THAT AREA...WITH DIMINISHING RAIN CHANCES TO THE WEST. LATEST HRRR RUN SHOWS SOME SHOWERS DEVELOPING BACK FURTHER TO THE WEST TOWARDS DAWN AND WITH THE FILLING UPPER LOW NEARBY...WILL MAINTAIN AT LEAST A 20 POP EVERYWHERE THROUGH THE NIGHT INTO THE DAY TOMORROW. OTHERWISE...ADDED PATCHY FOG INTO THE FORECAST AS ANY BREAKS IN THE CLOUDS WILL ALLOW IT TO FORM RATHER QUICKLY OVERNIGHT BUT NO OTHER CHANGES WERE NEEDED AT THIS TIME. && .SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT) ISSUED AT 220 PM EDT SUN AUG 18 2013 UPPER LOW SPINNING OVER WRN KY WILL CONTINUE TO EASE TO THE EAST AS HIGH PRESSURE SLOWLY RELEASES IT/S HOLD ON THE REGION AND SLIPS TO THE MID ATLANTIC COAST. MEANWHILE A SFC LOW COMING ONSHORE NEAR THE MID GULF COAST CONTINUES TO PUSH MOISTURE AND A BLANKET OF CLOUDS INTO ERN KY. EXPECT THE RAIN TO CONTINUE OVER ERN KY FOR THE NEXT 24-30 HRS AS THE UPPER LOW EDGES ACROSS THE STATE AND FINALLY MOVES NE TOWARDS THE NEW ENG COAST. THE GULF COAST LOW WILL SLOWLY TRACK NE AND LINK UP WITH THE UPPER LEVEL SYSTEM BEFORE SWEEPING INTO THE POCONOS. HIGH PRESSURE WILL THEN BUILD BACK INTO THE AREA AND GIVE THE REGION A SMALL WINDOW TO DRY OUT ON MON NIGHT. BUT THE MOISTURE SPLAYED ACROSS THE AREA TODAY AND TONIGHT WILL SET THE STAGE FOR FOG MON NIGHT AS A FEW BREAKS IN THE CLOUD COVER WILL ALLOW TEMPS TO DROP FROM A MON HIGH AROUND 80 TO LOWS AT OR NEAR THE DEWPOINT TEMPS IN THE LOWER 60S FOR MON NIGHT. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 231 PM EDT SUN AUG 18 2013 MODELS HAVE CHANGED COURSE A BIT GOING INTO TUESDAY AND WEDNESDAY AS ANOTHER MID/UPPER LEVEL LOW WILL DEVELOP OVERHEAD. ON TUESDAY...MOISTURE WILL BE ON THE INCREASE FROM THE SOUTH. MUCH LIKE ON SATURDAY...DOWNSLOPING SOUTHEAST WINDS WILL HAMPER THE NORTHWARD PROGRESS OF ANY PRECIPITATION AND KEEP INSTABILITY AT BAY. THUS...GOING TO CONFINE POPS TO MAINLY THE SOUTHERN 2 ROWS OF COUNTIES IN KENTUCKY WITH ONLY A SLIGHT CHANCE. AREAS FURTHER NORTH WILL LIKELY BE AFFECTED BY THE DOWNSLOPING CONDITIONS. BY TUESDAY NIGHT...AS THE UPPER LEVEL LOW PUSHES SLIGHTLY EAST...WINDS WILL VEER AROUND TO THE SOUTH OR SOUTHWEST ALLOWING MOISTURE TO SURGE NORTHWARD. CLOUDS AND SHOWERS WILL OVERSPREAD THE AREA FROM LATE TUESDAY NIGHT INTO WEDNESDAY. A MID LEVEL VORTICITY MAXIMUM WILL PUSH EAST DURING THE DAY TO AID IN MORE VIGOROUS SHOWER ACTIVITY. STILL SOME QUESTION AS TO INSTABILITY DURING THE DAY...AND MUCH LIKE TODAY...CLOUD COVER COULD LIMIT INSTABILITY KEEPING ANY THUNDER AT BAY. GOING TO CARRY A SLIGHT CHANCE FOR NOW...BUT FEEL THIS THUNDER PROBABLY WILL NOT PAN OUT. THIS SYSTEM WILL FINALLY BE ON THE WAY OUT BY THURSDAY WITH THE EXPECTED RIDGING FINALLY BUILDING ACROSS THE REGION. THIS WILL SET UP THE SUMMER-LIKE PATTERN BY THURSDAY AND THROUGH NEXT WEEKEND. THIS WILL YIELD A MINIMAL CHANCE FOR SHOWERS OR STORMS EACH AFTERNOON...BUT ANTICIPATING THAT MOST AREAS WILL REMAIN DRY FROM WEDNESDAY NIGHT ONWARD. TEMPERATURES WILL REMAIN A TOUCH BELOW NORMAL INTO WEDNESDAY WITH THE CLOUD COVER AND PRECIPITATION...BUT WILL WARM TO NEAR NORMAL FOR THE SECOND HALF OF THE WEEK...AND AT THIS POINT...LOOKING FOR SLIGHTLY ABOVE NORMAL READINGS BY NEXT WEEKEND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 137 AM EDT MON AUG 19 2013 STILL BELOW AVERAGE CONFIDENCE IN FORECAST DETAILS FOR AREA AIRPORTS TONIGHT AS CLOUDS ARE EXPECTED TO BREAK UP ENOUGH TO ALLOW FURTHER LOW CLOUD AND FOG DEVELOPMENT OVERNIGHT WITH AMPLE LOW LEVEL MOISTURE IN PLACE. HAVE FORECAST DETERIORATING CONDITIONS AT ALL 3 TAF SITES WITH A PERIOD OF LIFR CIGS AND VSBYS AROUND DAWN. SHOULD MID LEVEL CLOUDS HOLD ON THROUGH THE NIGHT...THIS WILL BE TOO PESSIMISTIC. OTHERWISE...A FEW STRAY SHOWERS WILL BE POSSIBLE OVERNIGHT AND AGAIN TOMORROW. WILL HANDLE THIS WITH A VCSH MENTION AT THIS TIME. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...DUSTY LONG TERM...KAS AVIATION...AR
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
128 AM EDT Mon Aug 19 2013 ...Updated Aviation Discussion... ...Forecast Update... Issued at 1140 PM EDT Sun Aug 18 2013 One more update to bump up coverage of fog some. Seeing visibilities drop in a few spots late this evening. The clear spot to our west has seen PAH drop down to a quarter mile in its latest ob. Will have to watch for worse visibilities over our area tonight, but for now the trend looks good. Still cannot rule out a stray shower developing, as the upper trough axis still has not passed our region. Have left in a slight chance across the southeast for a few more hours tonight. Issued at 625 PM EDT Sun Aug 18 2013 Active convection appears confined to a line running from north of Hartford to west of Lawrenceburg in KY. Fine tuned the rain chances to focus on this region next couple of hours. Still expect activity to quiet down with loss of heating and as the upper low, which has been near us for days, weakens and accelerates northeast. Next issue will be the chance for fog. Statistical guidance hints at visibilities lowering during the night, and this makes sense with residual moisture. Cloud cover should keep us from going too dense however. For now have added in patchy fog everywhere after midnight. .SHORT TERM (Now through Monday Night)... Issued at 300 PM EDT Sun Aug 18 2013 The cutoff upper low that was centered over the Mississippi and Ohio River confluence this morning is filling, becoming an open wave, and meandering eastward, as another shortwave trough begins to dive southeast into the upper Mississippi Valley. Scattered showers and isolated storms will be possible through the afternoon and early evening hours, as heating combines with large-scale ascent. The mid-level trough axis will swing across the area tonight, combined with loss of heating, will put an end to convection. So, will have scattered precipitation tapering off from west to east through the evening hours, with a dry forecast from about midnight onward. Will continue with dry conditions through Monday morning. However, the trough across the upper Mississippi Valley tonight will spread across the Ohio Valley by Monday afternoon. Appears some low-level moisture will remain in place and with afternoon heating, could spark some convection. Soundings indicate there should be slight capping across much of the CWA, allowing mainly low-topped showers to develop. By late in the afternoon the cap could weaken just enough to squeeze out an isolated thunderstorm or two, but that chance appears minimal. So, will run with isolated showers in the forecast through the afternoon and early evening hours Monday. This will generally be along and southeast of a line from Frankfort southwestward to Bowling Green. Any activity will dissipate with loss of heating, leaving the overnight hours dry. Temperatures will drop into the lower 60s tonight, with a few breaks in the cloud cover. Highs in the low to middle 80s will be common Monday under partly cloudy skies. Expect lows in the low and middle 60s Monday night under partly cloudy to mostly clear skies. Cannot rule out some patchy fog tonight and Monday night, but tonight will depend on how much cloud cover is lost and Monday night will depend on how much drying occurs through Monday afternoon. .LONG TERM (Tuesday through Sunday)... Issued at 300 PM EDT Sun Aug 18 2013 The long term period continues to look rather unsettled for much of the upcoming work week as the Ohio Valley will remain in a rather stagnant upper level pattern. However, the overall pattern looks to improve a bit by the end of the week and into the weekend as the latest forecast datasets point to upper level ridging building in from the west which will result in warmer and more seasonal temperatures for the region. Until late week, the upper level flow is forecast to remain rather blocky and complex as the band of westerlies remains holed up along the US/Canadian border. Overall, there is not much forcing in the hemispheric flow to kick things into gear and smooth the wave pattern out. With that said, the model solutions show that a bagging long wave trough axis will remain over the eastern part of the US from Tuesday through at least late Thursday. With the trough axis overhead, diurnally driven convection will be possible across the region. While the overall coverage for the week looks to be isolated to scattered, it does appear that the best chances for rainfall would be Wednesday as the actual trough pulls through the region. With this forecast we plan on keeping isolated-scattered PoPs in the forecast each afternoon for Tuesday-Thursday with the highest chances Wednesday. With regards to convection strength, the combination of weak flow aloft and rather modest instability suggests that severe weather is not likely. However, high atmospheric moisture content combined with the weak steering flow could lead to heavy rain production with any storm that develops. Temperatures through the period will remain below normal. Have sided again with the consensus raw datasets for max/min temperatures as they have verified well over the last few days. This actually results in a cooling trend applied for Tuesday/Wednesday due to expected clouds and precipitation. Tues/Wed highs will average in the lower 80s across the central/east/southeast with lower-middle 80s across the northwest/west sections. With the upper trough passing to our east on Thursday, we expect less clouds and precipitation which should allow temperatures to warm into the middle 80s. Overnight lows will be rather mild with readings in the upper 60s to the lower 70s. By Friday, the model solutions start to show their normal spread. The GFS solutions suggest a weak cold front will pass through the region and then stall out to our south. On the other hand, the Euro solution is not as progressive and allow the upper ridging to build in which would keep the frontal boundary up to our north. For now have, opted to keep the forecast on the dry side, but will continue to monitor later forecasts to see if PoPs will be required. With the upper ridge building in, Sat/Sun continue to look dry at this point. Temperatures should continue to moderate through the period with afternoon highs in the middle to upper 80s with overnight lows in the upper 60s to the lower 70s. && .AVIATION (06Z TAF Update)... Issued at 125 AM EDT Mon Aug 19 2013 The TAF challenge this morning will be the extent and intensity of fog and low cigs over the TAF sites as we sit in a very moist environment with weak or calm winds. Observations across the region reveal 2 areas of fog/low cigs...one over Illinois/western KY and the other over southwest Ohio. The RAP is picking up on these areas of fog/low cigs well and forecasts that they will expand into SDF/BWG/LEX as the morning progresses. LEX seems to be the most likely to see the worst flight conditions with MVFR conditions likely to develop within the next few hours and decline to LIFR by around 9 or 10Z. BWG/SDF seem to be more on the edges of the projected fog/low cigs. Since BWG is very fog prone, did go ahead and bring flight conditions into the LIFR cat by 9Z with a slightly slower progression to that restriction than LEX. SDF seems to be the least likely to see really low vsbys/cigs although based on the latest RAP guidance, they will probably drop into the IFR cat just before sunrise. If the fog/low cigs expand more than projected by the RAP, SDF TAF will need to be amended with more flight restrictions. Fog/low cigs should improve by 13 or 14Z with VFR conditions expected the rest of the day with a light ENE wind. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Update.........RJS Short Term.....MJP Long Term......MJ Aviation.......AMS
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
341 AM EDT MON AUG 19 2013 .SYNOPSIS... AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE REGION TODAY AND HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT THROUGH TUESDAY. A TROUGH WILL IMPACT THE REGION DURING THE MIDDLE PORTION OF THE WEEK BEFORE A COLD FRONT MOVES THROUGH FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... HAVE HAD SOME POCKETS OF CLEARING EARLY THIS MORNING WITH WEAK SURFACE HIGH PRESSURE NEARBY. WITH LINGERING LOW LEVEL MOISTURE...THIS HAS RESULTED IN PATCHY FOG MAINLY ACROSS THE SHENANDOAH VALLEY/NORTHERN VIRGINIA PIEDMONT AREA. THIS WILL PERSIST UNTIL SUNRISE. ALSO HAVE SOME SHOWERS ACROSS SOUTHWEST VIRGINIA THAT EXIST AHEAD OF AN UPPER TROUGH OVER THE OHIO VALLEY. HRRR HAS SHOWERS MAKING THEIR WAY INTO THE SOUTHWEST CWA OVER THE NEXT SEVERAL HOURS. AS THE TROUGH ADVANCES EASTWARD THROUGH THE DAY...ANTICIPATE NEW SHOWER DEVELOPMENT IN THE PVA ZONE LATER THIS MORNING WEST OF THE BLUE RIDGE AND THEN SPREADING EAST TOWARD THE METRO CORRIDOR IN THE AFTERNOON. DUE TO CLOUD COVER...INSTABILITY IS FORECAST TO BE WEAK AND LIKELY LESS THAN 500 J/KG. THEREFORE HAVE ONLY ALLOWED FOR ISOLATED THUNDER DURING THE AFTERNOON AND NO SEVERE IS EXPECTED. SHOWERS WILL BE QUICK TO DISSIPATE THIS EVENING WITH THE SETTING OF THE SUN AND WITH THE SHORTWAVE EXITING THE AREA. HIGH PRESSURE BUILDS IN OVERNIGHT...AND FOG COULD BE MORE WIDESPREAD ESPECIALLY IF CLEARING OCCURS. && .SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/... SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION TUESDAY INTO TUESDAY NIGHT...BRINGING DRY AND SEASONABLE CONDITIONS. MAX TEMPS TUESDAY WILL RANGE FROM THE UPPER 70S IN THE MOUNTAINS TO THE MIDDLE AND UPPER 80S ACROSS MOST OTHER LOCATIONS. MIN TEMPS TUESDAY NIGHT WILL RANGE FROM THE 50S IN PORTIONS OF THE POTOMAC HIGHLANDS TO THE LOWER AND MIDDLE 70S IN DOWNTOWN WASHINGTON AND BALTIMORE. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... HIGH PRESSURE WILL MOVE OFF THE COAST WEDNESDAY AND A RETURN FLOW WILL USHER IN WARM AND HUMID CONDITIONS. AN UPPER-LEVEL LOW WILL ALSO BUILD TOWARD THE REGION FROM THE OHIO VALLEY. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE...ESPECIALLY ACROSS THE SHENANDOAH VALLEY AND POTOMAC HIGHLANDS...CLOSER TO THE UPPER-LEVEL LOW. THE UPPER-LEVEL LOW WILL WEAKEN AND ROTATE THROUGH AS AN UPPER-LEVEL TROUGH WEDNESDAY NIGHT AND THURSDAY. A SURFACE TROUGH WILL ALSO REMAIN OVER THE REGION DURING THIS TIME. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE...BUT MUCH OF THE TIME MAY TURN OUT DRY. TEMPERATURES WILL BE NEAR CLIMO. A COLD FRONT WILL PASS THROUGH THE REGION FRIDAY...BRINGING THE CHANCE FOR MORE SHOWERS AND THUNDERSTORMS. HIGH PRESSURE MAY BUILD IN BEHIND THIS SYSTEM DURING THE WEEKEND. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... GREATEST POTENTIAL FOR FOG THIS MORNING WILL BE CHO...WITH A PERIOD OF IFR IN THE TAF. CONFIDENCE IN LOW VIS DECREASES FURTHER NORTHEAST WHERE DEWPOINTS ARE LOWER BUT BRIEF MVFR AT MRB/IAD IS POSSIBLE. SHORTWAVE TROUGH WILL BRING SCATTERED SHOWERS...PROBABLY NOT UNTIL THE AFTERNOON AT THE HUBS. AS HIGH PRESSURE BUILDS IN TONIGHT...VIS RESTRICTIONS COULD BE MORE WIDESPREAD AND/OR LOWER LATE TONIGHT. AREAS OF BR/FOG WILL LIKELY IMPACT THE TERMINALS EARLY TUESDAY MORNING. VFR CONDITIONS ARE EXPECTED FOR THE REST OF TUESDAY INTO TUESDAY NIGHT. PATCHY BR/FOG MAY IMPACT THE TERMINALS LATE TUESDAY NIGHT. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE WEDNESDAY AND THURSDAY...BUT MUCH OF THE TIME MAY TURN OUT DRY. A COLD FRONT MAY PASS THROUGH THE TERMINALS FRIDAY. && .MARINE... WEAK GRADIENT WILL GENERALLY KEEP WINDS AOA 10 KT THROUGH TONIGHT. WEAK TROUGH MAY BRING A FEW SHOWERS THIS AFTERNOON...THEN HIGH PRESSURE BUILDS IN OVERNIGHT. HIGH PRESSURE WILL REMAIN OVER THE WATERS TUESDAY BEFORE MOVING OFF THE COAST WEDNESDAY. A RETURN FLOW WILL DEVELOP WEDNESDAY THROUGH THURSDAY. WIND SPEEDS SHOULD REMAIN BELOW SCA CRITERIA DURING THIS TIME. A COLD FRONT WILL PASS THROUGH THE WATERS LATE FRIDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BJL NEAR TERM...BPP SHORT TERM...BJL LONG TERM...BJL AVIATION...BJL/BPP MARINE...BJL/BPP
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
404 AM EDT MON AUG 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 359 AM EDT MON AUG 19 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A ZONAL FLOW OVER SRN CANADA TO THE N OF UPR RDG EXTENDING FM THE WRN PLAINS INTO THE GREAT LKS. THE WX OVER UPR MI IS QUIET EARLY THIS MRNG...WITH DRY/STABLE AIRMASS DEPICTED ON THE 00Z MPX/GRB RAOBS DOMINATING THE AREA. THERE ARE 2 SHRTWVS EMBEDDED IN THE ZONAL FLOW THAT ARE OF CONCERN. THE FIRST OF THESE IS MOVING EWD THRU THE DAKOTAS AND ARPCHG NW MN...ACCOMPANIED BY SCT SHRA/TS. THE SECOND IS MOVING THRU NW ONTARIO WITH A CLUSTER OF SHRA/TS NW OF LK NIPIGON...BUT SOME ISOLD SHRA/TS WITHIN THE COMMA TAIL OF THIS FEATURE EXTEND FARTHER S INTO THE MN ARROWHEAD UNDER SOME H85-5 QVECTOR CNVGC ASSOCIATED WITH FAIRLY VIGOROUS H85 THETA E ADVECTION IN ADVANCE OF AXIS OF HIER H85 DEWPTS UP TO 15C AT ABERDEEN SDAKOTA AND 13C AT INL. WHILE THE 00Z MPX/GRB RAOBS ARE QUIET DRY/STABLE WITH KINX OF 0/-2 RESPECTIVELY AND PWAT ARND 0.75 INCH /NEAR 75 PCT OF NORMAL/...THE 00Z INL RAOB IS MORE MOIST AND CONDITIONALLY UNSTABLE...WITH KINX OF 36 AND PWAT 1.47 INCH /175 PCT OF NORMAL/. DESPITE THE RATHER IMPRESSIVE MOISTENING...LATEST TRENDS INDICATE FEW IF ANY LTG STRIKES WITHIN THE CONVECTION. MAIN FCST CONCERNS IN THE SHORT TERM ARE RELATED TO PCPN CHCS ASSOCIATED WITH PAIR OF SHRTWVS NOTED ABOVE. TDAY...SHRTWVS MOVING INTO MN AND THRU ONTARIO ARE PROGGED TO CONTINUE DRIFTING E THRU THE DAY. AS AXIS OF VIGOROUS H85 THETA E ADVECTION/H85-5 QVECTOR CNVGC SHIFT E THIS MRNG...EXPECT SOME ISOLD SHRA TO INVADE THE WRN COUNTIES. BUT MODEL GUIDANCE IN GENERAL SHOWS THE SHARPER H85-5 QVECTOR CNVGC ASSOCIATED WITH THE ONTARIO SHRTWV PASSING TO THE N AND MORE VIGOROUS FORCING IN ADVANCE OF THE MN DISTURBANCE FOCUSING TO THE S BEFORE FADING IN THE AFTN. SO GOING FCST SHOWING A DIMINISHING TREND IN THE POPS THRU THE MRNG SEEMS ON TRACK. GIVEN OBSVD LTG STRIKES AND TENDENCY FOR DIMINISHING DYNAMIC SUPPORT...REMOVED MENTION OF TS THIS MRNG. WHETHER DAYTIME HEATING /DESTABILIZATION CAN REINVIGORATE/SUSTAIN ANY CONVECTION WL BE THE CONCERN FOR THE AFTN. IN FACT...THE 00Z REGIONAL GEM AND GFS ARE THE ONLY MODELS THAT GENERATE ANY PCPN OVER THE CWA THIS AFTN. THE GFS FCST SDNGS SHOW RATHER UNIMPRESSIVE LAPSE RATES WITH A TENDENCY FOR A PERSISTENT CAP AND WARMING MID LVL TEMPS IN THE 18Z-24Z TIME FRAME ASSOCIATED WITH THE FADING DYNAMIC SUPPORT. NAM/GFS MOS POPS ARE UNDER 10 AT MOST PLACES...BUT OPTED TO RETAIN SCHC POPS TO INCLUDE TS WITH ARRIVAL OF MOISTER AIR/PWAT UP TO 1.5 INCH AND SFC TEMPS EXPECTED TO REACH ARND 85 THAT WL LIFT MUCAPE UP TO 800-1000J/KG AWAY FM THE MODERATING INFLUENCE OF THE LKS. TNGT...WITH RISING HGTS/DNVA/DEEP QVECTOR DVGC...TNGT WL BE DRY AS ANY AFTN CONVECTION FIZZLES BEFORE SUNSET UNDER THE MID LVL WARMING/LOWERING SUN ANGLE. ALTHOUGH SKIES WL TURN MOCLR...STEADY SW WIND SHOULD ACT TO LIMIT THE DIURNAL TEMP FALL. THE WARMEST MIN TEMPS ARE MOST LIKELY NEAR LK SUP OVER THE W HALF...WHERE THE PRES GRADIENT WL BE A BIT TIGHER/H925 WINDS 20-25 KTS AND THIS FLOW WL DOWNSLOPE. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 359 AM EDT MON AUG 19 2013 STARTING TUE...THE CWA WILL BE BETWEEN A SFC HIGH OVER THE ATLANTIC/ERN CONUS AND AND SFC TROUGH FROM HUDSON BAY INTO THE NRN PLAINS STATES. SOME OF THE MODELS ARE HINTING AT SOME PRECIP TUE AFTERNOON...BUT ANY PRECIP SHOULD BE ISOLATED AT BEST GIVEN THAT THERE WILL NOT BE MUCH MOISTURE AVAILABLE. BEST CHANCE FOR ISOLATED SHOWERS AND THUNDERSTORMS WILL BE OVER NCENTRAL UPPER MI WHERE LAKE BREEZE CONVERGENCE WILL HELP ENCOURAGE CONVECTION ALONG. 850MB TEMPS AT 18Z TUE WILL BE RIGHT AROUND 17-18C AND WITH MOSTLY SUNNY SKIES SHOULD BE ABLE TO GET HIGH TEMPS IN THE 80S TO AROUND 90. MODELS ARE IN BETTER AGREEMENT FOR THAT TROUGH/COLD FRONT TO THE NW TO DROP ACROSS THE CWA ON WED/WED NIGHT...BUT THERE REMAINS SOME SUBTLE YET IMPORTANT UNCERTAINTY FOR THE SYSTEM. MAIN QUESTION IS WITH THE EXACT TIMING OF THE COLD FRONT...WHICH EVEN THOUGH MODELS AGREE WELL ON...THINK THAT IT WILL NOT BE CERTAIN UNTIL A LATER TIME. THE TIMING OF FROPA IS IMPORTANT BECAUSE WITH 850MB TEMPS UP TO 20C...TEMPS MAY BE COLDER THAN WHAT IS IN THE FORECAST /MAINLY OVER THE W WHERE THE FRONT MAY COME IN EARLIER THAN PREVIOUSLY INDICATED BY MODELS/. THINK THAT AREAS THAT HAVE NOT BEEN IMPACTED BY THE FRONT /AND ASSOCIATED PRECIP AND CLOUD COVER/ BY AROUND PEAK HEATING TIME WILL GET INTO THE LOW 90S /AWAY FROM LAKE MICHIGAN/. SO...IF THE COLD FRONT COMES IN AS THE MODELS ARE CURRENTLY INDICATING /INTO WRN UPPER MI BY 18Z WED AND CENTRAL UPPER MI BY 00Z THU/...PORTIONS OF WRN UPPER MI WOULD SEE HIGH TEMPS POSSIBLY 10 DEGREES COLDER THAN WHAT THE PREVIOUS FORECAST HAD. ON THE FLIP SIDE...THE FRONT COULD VERY WELL COME IN LATER THAN INDICATED BY MODELS...MEANING THE PREVIOUS FORECAST MAY BE RIGHT ON. AT THIS POINT WITH THE UNCERTAINTY...WILL NOT CHANGE TEMPS MUCH FOR WED. THE OTHER IMPACT WITH FROPA TIMING IS ON CONVECTION...SIGNIFICANT SBCAPE VALUES OF 1500-2500J/KG SHOULD BE PRESENT IN AIRMASS AHEAD OF COLD FRONT AROUND PEAK HEATING...SO WHEN THE FRONT MOVES THROUGH WILL DETERMINE STRENGTH/COVERAGE OF CONVECTION. AT THIS POINT...NOT TOO EXCITED WITH AREAL EXTENT OF CONVECTION GIVEN THAT MOISTURE WILL BE SOMEWHAT LIMITED /AT LEAST EARLY ON/. AT THE SAME TIME...THAT DRY AIR WILL HELP DCAPE VALUES GET UP TO AROUND 1000J/KG AND WITH HIGH FREEZING LEVEL AROUND 14KFT...MAIN THREAT FROM ANY STRONGER OR ISOLATED SEVERE STORMS WOULD BE STRONG WINDS. THURSDAY CERTAINLY LOOKS COOLER AND DRIER AS 850MB TEMPS AT 18Z THU WILL BE AROUND 13C WITH SFC HIGH PRESSURE MOVING IN FROM THE W. HIGH TEMPS LOOK TO BE IN THE 70S TO AROUND 80 OVER THE SCENTRAL CWA. AMPLIFIED UPPER LEVEL RIDGE WILL BE WELL TO THE W OF THE CWA. MODELS IN MUCH BETTER AGREEMENT FOR FRI WITH HAVING THE SFC HIGH EXIT TO THE E ON FRI AS THE UPPER RIDGE AXIS MOVES OVERHEAD LATE IN THE DAY. WITH SLY FLOW NOT KICKING IN AND UPPER RIDGE NOT ARRIVING UNTIL LATE IN THE DAY OR UNTIL FRI NIGHT...WILL NOT HAVE SUFFICIENT ADVECTION OF WARMER AIRMASS INTO THE AREA. HIGH TEMPS LOOK SIMILAR OR A DEGREE OR TWO COOLER THAN THURSDAY...WITH HIGHS PRIMARILY IN THE 70S /WITH SOME COOLER SPOTS NEAR LAKE SUPERIOR/. UNCERTAINTY INCREASES CONSIDERABLY FOR SAT AND SUN DUE TO MODEL DISAGREEMENT AND RUN TO RUN DISCONTINUITY. WILL JUST USE CONSENSUS OF MODELS FOR THIS PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 121 AM EDT MON AUG 19 2013 WITH SW FLOW OF RELATIVELY DRY AIR...EXPECT VFR CONDITIONS TO PREVAIL THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. INCREASING SW WINDS ABOVE NOCTURNAL INVERSION LATE TONIGHT WILL APPROACH LLWS CRITERIA. ALSO A DISTURBANCE APPROACHING FROM THE W MAY BRING ISOLD/SCT CONVECTION INTO CENTRAL UPPER MI LATE MON AFTERNOON. AT THIS POINT...CONFIDENCE IS VERY LOW ON LOCATION/COVERAGE OF SHRA/TSRA. THUS...WILL ONLY MENTION VCSH AT KSAW AROUND 21Z MON. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 359 AM EDT MON AUG 19 2013 OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE GREAT LAKES REGION. THE ARRIVAL OF MORE HUMID AIR FOR TUE/WED MAY RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL BE MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE. ANY FOG WILL DISSIPATE THU FOLLOWING A COLD FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...TITUS AVIATION...VOSS MARINE...KC
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
121 AM EDT MON AUG 19 2013 .SHORT TERM...(THIS EVENING THROUGH MONDAY) ISSUED AT 409 PM EDT SUN AUG 18 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A RIDGE OVER THE SRN U.S. ROCKIES WITH A TROF LINGERING OVER THE LWR MISSISSIPPI VALLEY. TO THE N...ZONAL FLOW DOMINATES SRN CANADA. THERE ARE A COUPLE OF SHORTWAVES OF INTEREST UPSTREAM IN THIS ZONAL FLOW. THE FIRST IS OVER SE MANITOBA...AND THE SECOND IS OVER SRN SASKATCHEWAN/ERN MT. THE FIRST WAVE IS GENERATING CONVECTION OVER FAR SE MANITOBA INTO ADJACENT NRN ONTARIO. THE SECOND WAVE IS GENERATING SCT SHRA/TSRA OVER THE WRN DAKOTAS INTO SRN SASKATCHEWAN. CLOSER TO HOME...12Z SOUNDINGS FROM KGRB/KMPX SHOWED VERY DRY MID LEVELS AND A HEALTHY CAP...AND THUS NO PCPN IS OCCURRING OVER THE FCST AREA THIS AFTN. SOME CI AND A RATHER THICK ELEVATED SMOKE LAYER HAS HELD TEMPS DOWN A BIT FROM EXPECTATIONS WITH READINGS MOSTLY IN THE UPPER 70S TO LOW 80S AS OF 19Z. NEAR LAKE MICHIGAN...SOUTHERLY WINDS OFF THE LAKE ARE HOLDING TEMPS TO THE LOW/MID 70S. AFTER A DRY START TO THE SHORT TERM...ATTENTION TURNS TO THE POTENTIAL OF SHRA/TSRA LATE TONIGHT/MON AS THE PAIR OF SHORTWAVES CURRENTLY OVER SE MANITOBA AND OVER SRN SASKATCHEWAN/ERN MT MOVES EASTWARD. INITIAL DRY/CAPPED AIR MASS WILL ENSURE DRY WEATHER ACROSS THE FCST AREA THIS EVENING. THEN...SW FLOW AHEAD OF SHORTWAVES WILL TRANSPORT INTO THE UPPER LAKES THE MORE HUMID AIR MASS EVIDENT OVER THE CNTRL PLAINS THIS MORNING PER 12Z RAOBS. WHILE THE ANTECEDENT DRY AIR WILL WORK TO DELAY SHRA...DEGREE OF MOISTENING/MAGNITUDE OF THETA-E ADVECTION SUGGESTS THERE WILL BE SOME RISK OF PCPN. THERE MAY BE 2 RATHER DISTINCT CLUSTERS OF SCT SHRA/TSRA. THE FIRST ASSOCIATED WITH THE SE MANITOBA SHORTWAVE COULD REACH NW LAKE SUPERIOR/ISLE ROYALE AREA EARLY IN THE OVERNIGHT. 850-300MB THICKNESS FIELD SUGGESTS SOME OF THE CURRENT SHRA/TSRA ASSOCIATED WITH THE WAVE MAY TAKE A SHARP TURN TO THE RIGHT AS THEY APPROACH THE LAKE...SO IT REMAINS TO BE SEEN WHERE THESE SHRA MAY END UP. THE SECOND AREA OF CONVECTION MAY DEVELOP ACROSS NRN MN TOWARD WRN LAKE SUPERIOR LATE IN THE NIGHT OR MON MORNING WITH THE FOLLOWING SHORTWAVE. IN BOTH CASES...THERE IS AN INDICATION OF WEAKENING MOISTURE TRANSPORT EASTWARD WITH TIME...SO SHRA WILL PROBABLY BE ON A DIMINISHING TREND AS THEY MOVE TOWARD LAKE SUPERIOR/UPPER MI. AT THIS POINT...SEE NO REASON TO DEVIATE MUCH FROM INHERITED FCST WHICH BROUGHT CHC POPS TO WRN LAKE SUPERIOR OVERNIGHT AND SCHC POPS TO WRN UPPER MI LATE. INCREASING COLUMN MOISTURE AND STIRRING S TO SW WINDS WILL WORK TO KEEP TEMPS HIGHER THAN LAST NIGHT. EXPECT MINS IN THE MID 60S IN THE DOWNSLOPE AREAS NEAR LAKE SUPERIOR. MINS IN THE MID 50S TO PERHAPS AS LOW AS 50F IN TRADITIONAL COLD SPOTS SHOULD BE THE RULE INLAND. ON MON...SHORTWAVE TROF MOVES ACROSS THE UPPER LAKES...BUT WILL BE WEAKENING AS EVIDENT IN HEIGHT FIELD AND DEEP LAYER FORCING PER QVECTORS. IF ANY SHRA/TSRA REACH THE W LATE TONIGHT...THEY WILL LIKELY WEAKEN IN THE MORNING. DURING THE AFTN...MLCAPE IS FCST TO INCREASE TO POSSSIBLY AS MUCH AS 800-1000J/KG. HOWEVER...WITH DIMINISHING FORCING AND POTENTIALLY LITTLE IN THE WAY OF LAKE BREEZE CONVERGENCE...COVERAGE OF ANY DIURNALLY DRIVEN CONVECTION WILL PROBABLY BE QUITE LIMITED. WILL MAINTAIN JUST SCHC POPS FOR THE AFTN HRS. MAX TEMPS SHOULD GENERALLY BE IN THE MID 80S PER FCST SOUNDINGS. OF COURSE...SOUTHERLY WINDS WILL KEEP AREAS NEAR LAKE MICHIGAN A LITTLE COOLER. .LONG TERM...(MONDAY NIGHT THROUGH SUNDAY) ISSUED AT 409 PM EDT SUN AUG 18 2013 STARTING OUT ON MONDAY EVENING THE UPPER AIR PATTERN LOOKS ZONAL WITH WEAK TROUGHING OVER THE GREAT LAKES AND A RIDGE CENTERED OVER THE SOUTHWEST CONUS. RIDGE WILL HAVE HARD TIME AMPLIFYING FARTHER NORTH INTO CANADA THIS WEEK THOUGH AS STRONGER WESTERLIES H5-H3 STREAM ACROSS SOUTHERN TIER OF CANADA OUT OF A MORE OR LESS PERSISTENT TROUGH SET UP OVER GULF OF ALASKA. EVENTUALLY...WEDNESDAY NIGHT INTO THURSDAY...LARGER SCALE HEIGHTS FALL SOME AS STRONGER SHORTWAVE/JET MAX...PART OF WHICH IS STREAMING TOWARD WESTERN SHORE OF BRITISH COLUMBIA TODAY...DIGS ACROSS NORTHERN ONTARIO TO WESTERN QUEBEC. SFC COLD FRONT CROSSES UPPER LAKES WEDNESDAY AFTN INTO WEDNESDAY NIGHT JUST AHEAD OF BETTER HEIGHT FALLS BEGIN LATE WEDNESDAY. FRONT REPRESENTS BEST CHANCE OF SHRA/TSRA THIS WEEK. HIGH PRESSURE BUILDS IN BEHIND THE FRONT...BUT QUESTION OF THE DAY IS FOR HOW LONG. THIS WILL HAVE IMPACT ON FORECAST FOR FRIDAY THROUGH NEXT WEEKEND. INITIAL SHORTWAVE THAT ROLLS ACROSS UPPER LAKES ON MONDAY WILL MAINLY BE EAST OF CWA MONDAY EVENING. SOUNDINGS SHOW PERHAPS MID CLOUDS THROUGH THE NIGHT BUT WITH SUBSIDENCE IN WAKE OF WAVE...NOT EXPECTING ANY SHRA/TSRA. ANOTHER WARM NIGHT IN THE 60S WITH STEADY SW SFC WINDS BENEATH STRONGER WINDS AT 950-925MB. STRONGER WINDS ALOFT FADE BY TUESDAY AFTN WHICH MAY RESULT IN LOCALIZED BACKING OF WINDS/LAKE BREEZE ALONG LK SUPERIOR NCNTRL. LAKE MODIFICATION ONLY ALONG LK MICHIGAN ELSEWHERE. MID CLOUDS MAY DAMPEN SUN INITIALLY... BUT SHOULD SEE FULL SUN FOR A WHILE BTWN MID MORNING AND MID AFTN ALLOWING TEMPS TO WARM WELL INTO THE 80S AND PROBABLY TO THE LOWER 90S IN SOME WESTERN CWA LOCATIONS. WILL HAVE TO REACH AT LEAST MID 80S BEFORE CU BEGINS TO FORM AND CONVECTIVE TEMPS ARE ON THE HIGH SIDE IN THE LOWER 90S. SUPPOSE ALONG THE CONVERGENCE OF LAKE BREEZE THERE COULD BE AN ISOLD STORM GIVEN MLCAPES OVER 2000J/KG. MOISTURE THAT IS AROUND PER SOUNDINGS IS VERY SHALLOW SO WITHOUT MUCH ADDITIONAL LARGE SCALE SUPPORT...THINK CHANCES ARE VERY MINIMAL. IF A STORM CAN FORM...WOULD HAVE POTENTIAL FOR GUSTY WINDS AS DCAPE VALUES ARE OVER 1000J/KG. SOUNDINGS POINT TO QUIET...WARM AND HUMID CONDITIONS TUESDAY NIGHT IN THE WARM SECTOR. MAY SEE A TOUCH OF FOG...THOUGH SOME WIND JUST OFF THE SFC WILL LIMIT THE EXTENT. MOIST ONSHORE FLOW MAY LEAD TO MORE FOG CLOSER TO LK MICHIGAN SHORE. WARM WEATHER CONTINUES ON WEDNESDAY. AFTER A WARM START NEAR 70 DEGREES IN SOME SPOTS IT WILL NOT TAKE MUCH TO SEE READINGS REACH THOSE SIMILAR TO TUESDAY. COLD FRONT MAKES IT TO MN ARROWHEAD JUST TO WEST OF DLH BY MIDDAY SO A LOT OF TIME FOR WARMING IN A CAPPED AIRMASS WITH WARM NOSE AROUND 800MB. SOUNDINGS THROUGH 00Z THURSDAY LOOK PRETTY DRY WHICH MAKES SENSE AS PRIMARY SHORTWAVE AND MOISTURE ADVECTION IS NORTH OVR ONTARIO. SW WINDS COULD INCREASE THROUGH THE DAY AS 950-925MB WINDS INCREASE. STILL THINK TEMPS ON WEDNESDAY MAY END UP A BIT WARMER THAN TUESDAY WITH LATER ARRIVAL TO FRONT AND AS H85 TEMPS ARE NEAR +20C TO START THE DAY. DOWNSLOPE MAY LEAD TO FURTHER WARMING ALONG LK SUPERIOR FROM ONTONAGON TO MUNISING. WILL BUMP TEMPS INTO UPR 80S ON AVERAGE AND PUSH DOWNSLOPE AREAS TO AROUND 90. INSTABILITY OBVIOUSLY PRESENT AHEAD OF FRONT WITH THE VERY WARM TEMPERATURES AND INCREASE IN BLYR MOISTURE /DWPNTS ARE WELL INTO THE 60S/. RESULT IS MLCAPES 1500-2000J/KG JUST AHEAD OF THE FRONT. THINK QUALITY OF MOISTURE ULTIMATELY WILL LIMIT CONVECTION COVERAGE WITH THE FROPA. GIVEN THE INSTABILITY AND DEEP LAYER SHEAR UP TO 30 KTS THERE IS AT LEAST A MARGINAL POTENTIAL FOR ISOLD SVR STORMS THROUGH WEDNESDAY EVENING. HIGHER FREEZING LEVEL OVER 14KFT AND DRY AIR ALOFT /DCAPE OVER 1000J/KG/ POINTS TO STRONG WIND GUSTS AS MAIN HAZARD. GOOD AGREEMENT THAT STRONG DRYING/SUBSIDENCE ENDS ANY SHRA/TSRA OVERNIGHT WEDNESDAY NIGHT WITH THURSDAY STILL LOOKING MUCH COOLER AND MAINLY DRY AS HIGH PRESSURE BUILDS ACROSS UPPER GREAT LAKES. GUSTY NORTH TO NORTHWEST WINDS ALONG WITH COLD AIR ADVECTION SHOULD KICK UP WINDS AND WAVES ON LK SUPERIOR LEADING TO ELEVATED SWIM RISK. TEMPS WILL STRUGGLE TO 70 DEGREES NEAR LK SUPERIOR AND COULD REACH LOWER 80S FAR SOUTH. EVEN THOUGH THURSDAY IS AGREED UPON FOR COOLER AND MAINLY DRY WEATHER THE FORECAST FOR THURSDAY NIGHT INTO FRIDAY NOT NEARLY AS CLEAR CUT. GFS MAINTAINS CONTINUITY WITH RECENT RUNS BY SHOWING SPRAWLING HIGH SHUNTING MAIN FRONTAL BOUNDARY AND FOCUS FOR RETURN FLOW SHRA/TSRA OVER THE NORTHERN PLAINS AND OHIO VALLEY UNTIL AT LEAST SATURDAY NIGHT. MEANWHILE...ECMWF UP TO 12Z RUN TODAY WAS CONSISTENT SINCE 00Z RUN ON 17 AUG INDICATING ONLY A BRIEF HIGH PRESSURE INTRUSION. ECMWF THEN SHOWS NEXT SHORTWAVE IN WESTERLY FLOW FORMING A STRONGER SFC-H85 LOW OVER THE NORTHERN PLAINS THURSDAY WITH ASSOCIATED WARM AIR ADVECTION SHRA/TSRA IMPACTING UPPER LAKES AS EARLY AS THURSDAY NIGHT AND FRIDAY. ECMWF CERTAINLY ON THE AMPLIFIED SIDE COMPARED TO ECMWF ENSEMBLE WHICH LOOKS MORE LIKE THE OPERATIONAL GFS. LATEST ECMWF HAS BACKED AWAY FROM THIS IDEA THOUGH JUST ADDING MORE UNCERTAINTY TO THIS TIME FRAME. DROPPED POPS FOR THU NIGHT AND FRIDAY TO SLIGHT CHANCE...BUT WANTED TO KEEP SOME POPS IN THERE IN CASE MODELS SHIFT BACK TO WETTER IDEA. MUDDLED FORECAST CONTINUES THROUGH NEXT WEEKEND AS TIMING FOR SYSTEMS MOVING THROUGH REST OF THE WEEKEND IS STILL OUT OF WHACK BTWN THE GFS AND ECMWF. CONSENSUS APPROACH WORKS FOR NOW UNTIL THESE DETAILS CAN BE BETTER SORTED OUT. AFTER THE COOLER TEMPS THURSDAY AND FRIDAY...SEEMS THAT TEMPS WILL REACH BACK TOWARD NORMAL AND MAYBE EVEN ABOVE NORMAL IF THERE IS NOT MUCH IN WAY OF CLOUDS OR PRECIPITATION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 121 AM EDT MON AUG 19 2013 WITH SW FLOW OF RELATIVELY DRY AIR...EXPECT VFR CONDITIONS TO PREVAIL THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. INCREASING SW WINDS ABOVE NOCTURNAL INVERSION LATE TONIGHT WILL APPROACH LLWS CRITERIA. ALSO A DISTURBANCE APPROACHING FROM THE W MAY BRING ISOLD/SCT CONVECTION INTO CENTRAL UPPER MI LATE MON AFTERNOON. AT THIS POINT...CONFIDENCE IS VERY LOW ON LOCATION/COVERAGE OF SHRA/TSRA. THUS...WILL ONLY MENTION VCSH AT KSAW AROUND 21Z MON. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 409 PM EDT SUN AUG 18 2013 OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE GREAT LAKES REGION. SOME STRONGER SW WIND GUSTS UP TO 20-25KT MAY OCCUR TONIGHT UNDER A SHARPER PRES GRADIENT AHEAD OF AN APPROACHING DISTURBANCE. THE ARRIVAL OF MORE HUMID AIR FOR TUE/WED MAY RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL BE MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE. ANY FOG WILL DISSIPATE THU FOLLOWING A COLD FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLA AVIATION...VOSS MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
326 AM EDT MON AUG 19 2013 .SYNOPSIS... A WARM FRONT WILL GRADUALLY BRING MORE SEASONABLE TEMPERATURES OVER THE NEXT FEW DAYS. WEAK UPPER LEVEL DISTURBANCES WILL KEEP THUNDERSTORMS SCATTERED THROUGH THE MIDDLE OF THE WEEK. THE LATE WEEK PERIOD WILL TURN EVEN WARMER WITH LOWER RAIN CHANCES. && .NEAR TERM /THROUGH TONIGHT/... AS OF 3 AM MONDAY...MODEL GUIDANCE EJECTS THE UPPER LOW OVER THE MISSISSIPPI VALLEY TO THE NORTHEAST TODAY AND TONIGHT. THE MOTION OF THIS FEATURE WILL ALLOW LIFT ASSOCIATED WITH THE ENTRANCE REGION OF THE UPPER JET TO AFFECT THE AREA TODAY...PARTICULARLY NW SECTIONS. IN ADDITION MODEL GUIDANCE SHOWS WEAK ISENTROPIC LIFT OVER THE AREA TODAY AND THE OLD FRONTAL BOUNDARY REMAINS IN THE AREA AS WELL. FORECAST WILL HAVE HIGH CHANCE TO LIKELY POPS TODAY WITH HIGHEST NUMBERS NW...TAPERING BACK TO SLIGHT CHANCE TONIGHT. AFTERNOON MAXIMUM TEMPERATURES UNDER A PARTLY TO MOSTLY CLOUDY SKY SHOULD BE LIMITED TO THE MIDDLE 80S. MINS TONIGHT SHOULD FALL TO THE LOWER 70S...PERHAPS UPPER 60S NW. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 AM MONDAY...MODELS HAVE SLOWED IN SHOWING THE INLAND PROGRESSION OF THE MID LEVEL WEST ATLANTIC RIDGE. NOW TUESDAY IS DEPICTED AS ONE LAST DAY WHERE MOISTURE REMAINS DEEP AND A FEW WEAK SHORTWAVES EMBEDDED IN THE 10KT 500MB FLOW PROVIDE SOME SYNOPTIC SCALE ASCENT. TEMPERATURES WILL BE CLOSE CLIMO BUT SLIGHTLY HIGHER THAN NORMAL POPS APPEAR TO BE WARRANTED. WEDNESDAY THE WEST ATLANTIC RIDGE GAINS IN AMPLITUDE BACKING LOCAL FLOW ALMOST TO SOUTHERLY. MEANWHILE THE CHANNEL OF DEEPEST MOISTURE GETS SHUNTED JUST TO OUR WEST. ISO TO WIDELY SCATTERED CONVECTION TILL POSSIBLE ALONG MESOSCALE BOUNDARIES AND TEMPS MAY RISE A FEW DEG ABOVE TUESDAY COUNTERPARTS. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 3 AM MONDAY...FOR THE FIRST FEW DAYS OF THE LONG TERM THE WEST ATLANTIC UPPER RIDGE BUILDS IN FAVOR OF THE BUILDING RIDGE OVER THE WESTERN U.S. A WEAK SHEAR AXIS CROSSES THE REGION THURSDAY NIGHT INTO FRIDAY. WEAK ASCENT ASSOCIATED WITH THIS FEATURES SHOULD BRING SOME HIGHER RAIN CHANCES THAN WEDNESDAY BUT STILL PROBABLY NOT MUCH HIGHER THAN CLIMO. THE REMAINDER OF THE PERIOD KEEPS A STRONG UPPER RIDGE ACROSS THE MIDDLE OF THE NATION WITH TROUGHINESS ALONG BOTH COASTLINES. BARRING THE RELATIVELY NEW IDEA OF THE GFS OF A BACKDOOR COLD FRONT OVER THE WEEKEND THIS WILL MEAN SLIGHTLY ABOVE CLIMO TEMPS AND SLIGHTLY LOWER THAN NORMAL THUNDERSTORM COVERAGE. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 06Z...SURFACE DEWPOINTS IN THE LOW TO MID 70S WITH CALM/LIGHT WINDS SUGGEST THE LOW-LEVEL CONDITIONS ARE PRIMED FOR FOG/STRATUS OVERNIGHT. MVFR CIGS/VSBYS ARE EXPECTED AT THE COASTAL TERMS...WITH PERHAPS SOME BRIEF IFR VSBYS AT FOG-PRONE KCRE. KFLO/KLBT HAVE THE BEST CHANCES FOR IFR...AS THE LATEST GUIDANCE FAVORS STRATUS DEVELOPING AROUND DAYBREAK AT THE INLAND SITES. THE LATEST HRRR RUNS SHOW SOME SHOWERS MOVING ONSHORE IN THE EARLY MORNING HOURS...SO HAVE MENTIONED PCPN FOR THE COASTAL SITES AS WELL. CURRENT SHOWER ACTIVITY INLAND HAS A CHANCE TO AFFECT THE INLAND TERMINALS THROUGH ABOUT 09Z...PARTICULARLY FLO. MORE WIDELY SCATTERED SHOWERS ARE EXPECTED WITH DAYTIME HEATING AS A COASTAL TROUGH WILL BE POSITIONED OVER THE CAROLINAS. CIGS MAY BOUNCE AROUND BETWEEN VFR AND MVFR DURING THE DAY...WITH MVFR MORE LIKELY DURING PERIODS OF SHRA. SLIGHTLY HIGHER POPS INLAND ARE REFLECTED IN THE TAFS. CALM TO LIGHT WINDS WILL BECOME S-SE AOB 10 KTS AT KMYR...KCRE AND KILM IN THE AFTN HOURS. EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS POSSIBLE TUESDAY AND WEDNESDAY. ISOLATED TO SCATTERED AFTN SHOWERS/T-STORMS EXPECTED THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 3 AM MONDAY...OUTSIDE OF LIGHT N TO NW WINDS EARLY TODAY DUE TO A LAND BREEZE...EXPECT SE TO S FLOW AT 10 KT OR LESS THROUGH THE PERIOD. SEAS ARE EXPECTED TO RUN 2 TO 3 FT. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 AM MONDAY...TWIN CENTERED HIGH PRESSURE ON TUESDAY...ONE OFF THE COAST AND THE OTHER OVER THE MOUNTAINS. RESULTING FLOW ACROSS THE WATERS WILL BE QUITE LIGHT AND SOMEWHAT VARIABLE ALTHOUGH A PREDOMINANTLY SOUTHERLY COMPONENT WILL BE PRESENT. THE OVER LAND HIGH WILL BE SHRINKING ON WEDNESDAY WITH LITTLE EFFECT ON LOCAL WINDS AND THE CONTINUED DIMINUTIVE SEAS. LONG TERM /THURSDAY THROUGH FRIDAY/... AS OF 3 AM MONDAY...HIGH PRESSURE OVER THE LANDMASS/EASTERN U.S. DURING THE SHORT TERM FINALLY WASHES OUT ENOUGH TO BRING A MORE SEASONABLE SW FLOW ON THURSDAY AROUND THE WEST ATLANTIC HIGH. THIS FLOW CONTINUES INTO FRIDAY BUT MAY BE EQUALLY BORNE OF PIEDMONT TROUGHINESS AS THE WEAKENING WEST ATLANTIC RIDGE. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...MBB NEAR TERM...RAN SHORT TERM...MBB LONG TERM...MBB AVIATION...BJR/31
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
210 AM EDT MON AUG 19 2013 .SYNOPSIS... A DECAYING FRONTAL BOUNDARY WILL SLOWLY DISSIPATE ACROSS THE AREA AS A WESTERN ATLANTIC RIDGE BUILDS TOWARD THE COAST. TEMPERATURES MORE TYPICAL OF AUGUST WILL RETURN MUCH OF THIS UPCOMING WEEK WITH A FEW AFTERNOON THUNDERSTORMS. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... AS OF 1045 PM SUNDAY...LATEST SAT IMAGERY CONTINUES TO SHOW THE MOISTURE PLUME EXTENDING ALONG AND JUST EAST OF THE SPINE OF THE APPALACHIANS...FROM THE FLORIDA PAN HANDLE TO THE NE STATES. FLOW AROUND THE WESTERN ATLANTIC RIDGE HAS MUSCLED ITS WAY ACROSS THE COASTAL CAROLINAS...AND THUS PREVENTING THIS MOISTURE PLUME FROM ENCOMPASSING THE ENTIRE CWA TONIGHT INTO MONDAY. LATEST SREF INDICATES A LOW PROBABILITY FOR MEASURE-ABLE RAIN TONIGHT...AND HIGHLIGHTS 2 LOCATIONS...THE WESTERN FRINGES OF THE FA...AND ACROSS THE IMMEDIATE COAST FROM ANY ONSHORE MOVEMENT OF PCPN. LOOK FOR A RANGE OF 15 TO 40 POPS ACROSS THE FA OVERNIGHT. EARLIER INCREASE TO THE MIN TEMPS TONIGHTS REMAINS ON TARGET...NO ADDITIONAL TWEAKING NEEDED. WITH ONSHORE FLOW ACROSS 80+ DEGREE SSTS...MIN TEMPS ALONG THE IMMEDIATE BEACHES MAY STAY IN THE UPPER 70S TO AROUND 80. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... AS OF 3 PM SUNDAY...PRIMARY WEATHER STORY MONDAY AND TUESDAY WILL BE THE RETURN OF MORE TYPICAL AUGUST WEATHER ACROSS THE FORECAST AREA...AS REMNANTS OF AN UNSEASONABLE FRONTAL BOUNDARY THAT BROUGHT MINIMUM TEMPERATURES WELL INTO THE 60S AND HEARTY RAINFALL AMOUNTS RECENTLY...LOSES IDENTITY AND DISSIPATES OVER THE AREA. AN UPPER TROUGH PRESENTLY OVER THE MISSISSIPPI VALLEY WILL LIFT NE AND DAMPEN ACROSS NEW ENGLAND BY MONDAY NIGHT. THIS WILL ALLOW THE WESTERN EXTENT OF A STACKED BERMUDA RIDGE TO POKE LANDWARD ACROSS THE SE US COAST MONDAY AND TUESDAY. LINGERING LOW AND MID LEVEL MOISTURE ON MONDAY COUPLED WITH A WEAK COASTAL TROUGH MOVING INLAND SHOULD TRIGGER SCATTERED SHOWERS AND ISOLATED TSTMS DURING THE DAY ON MONDAY. BY TUESDAY HOWEVER...THE EFFECTS OF THE BERMUDA RIDGE PROGRESSING INLAND...WILL BE SEEN BY DRYING IN THE MIDDLE LEVELS OF THE ATMOSPHERE. WHILE WE CANNOT RULE OUT SHOWERS ON TUESDAY...COVERAGE SHOULD BE SUBSTANTIALLY HINDERED BY SUBSIDENT DRYING ALOFT. WE MAY SEE LOW CLOUDS EARLY MONDAY AS WELL AS CONVECTIVE DEBRIS CLOUDS DURING THE DAY...SO FOR MAXIMUMS AM EXPECTING MIDDLE AND UPPER 80S ACROSS THE REGION. EFFECTS OF THE RIDGE TUESDAY SHOULD ALLOW UPPER 80S MOST LOCATIONS WITH A FEW 90S ACROSS THE INTERIOR. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS OF 3 PM SUNDAY...THE 500 MB UPPER LEVEL RIDGE AXIS IS STILL TRYING TO TO BUILD WESTWARD AND WILL BE ALIGNED ALONG A LINE FROM MOBILE TO SAVANNAH ON THURSDAY. THE 12 UTC CYCLE OF THE GFS DEVELOPS A SECOND CUTOFF LOW SOUTH OF LAKE MICHIGAN ON WEDNESDAY AND LIFTS THIS FEATURE WELL NORTH OF THE AREA BY LATE THURSDAY. ALOFT A TROUGH IS CENTERED ALONG THE COAST AND NORTHWEST FLOW ALOFT WILL BE ESTABLISHED. THE GFS IS SHOWING AN UPPER LEVEL DISTURBANCE SHIFTING INTO THE CAROLINA BY THE END OF THE WEEK. AT THE SURFACE THE FRONTAL BOUNDARY WILL REMAIN AND THE MODELS CONTINUE TO SHOW A WEAKNESS IN THE SURFACE PRESSURE PATTERN THROUGH FRIDAY. PRECIPITABLE WATERS WILL REMAIN HIGH AND THE ONLY UPPER LEVEL SUPPORT MAY BE FROM SHORTWAVE IN THE NORTHWEST FLOW BY FRIDAY. THE UNCERTAINTY IS HOW MUCH IMPACT THESE DISTURBANCES WILL HAVE ON THE COAST. SO WITH THE CONFIDENCE NOT HIGH WENT WITH A CHANCE OF DIURNAL CONVECTION EACH DAY AND ONLY A SLIGHT CHANCE OVERNIGHT. MAXIMUM TEMPERATURES ARE EXPECTED TO BE NEAR 90 EACH DAY AND LOWS IN THE LOWER 70S INLAND AND MID 70S AT THE BEACHES. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 06Z...SURFACE DEWPOINTS IN THE LOW TO MID 70S WITH CALM/LIGHT WINDS SUGGEST THE LOW-LEVEL CONDITIONS ARE PRIMED FOR FOG/STRATUS OVERNIGHT. MVFR CIGS/VSBYS ARE EXPECTED AT THE COASTAL TERMS...WITH PERHAPS SOME BRIEF IFR VSBYS AT FOG-PRONE KCRE. KFLO/KLBT HAVE THE BEST CHANCES FOR IFR...AS THE LATEST GUIDANCE FAVORS STRATUS DEVELOPING AROUND DAYBREAK AT THE INLAND SITES. THE LATEST HRRR RUNS SHOW SOME SHOWERS MOVING ONSHORE IN THE EARLY MORNING HOURS...SO HAVE MENTIONED PCPN FOR THE COASTAL SITES AS WELL. CURRENT SHOWER ACTIVITY INLAND HAS A CHANCE TO AFFECT THE INLAND TERMINALS THROUGH ABOUT 09Z...PARTICULARLY FLO. MORE WIDELY SCATTERED SHOWERS ARE EXPECTED WITH DAYTIME HEATING AS A COASTAL TROUGH WILL BE POSITIONED OVER THE CAROLINAS. CIGS MAY BOUNCE AROUND BETWEEN VFR AND MVFR DURING THE DAY...WITH MVFR MORE LIKELY DURING PERIODS OF SHRA. SLIGHTLY HIGHER POPS INLAND ARE REFLECTED IN THE TAFS. CALM TO LIGHT WINDS WILL BECOME S-SE AOB 10 KTS AT KMYR...KCRE AND KILM IN THE AFTN HOURS. EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS POSSIBLE TUESDAY AND WEDNESDAY. ISOLATED TO SCATTERED AFTN SHOWERS/T-STORMS EXPECTED THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1045 PM SUNDAY...THE INVERTED SFC TROF OR COASTAL FRONTAL BOUNDARY...REMAINS STATIONARY ALONG THE IMMEDIATE COAST OF THE CAROLINAS FROM CAPE HATTERAS SOUTHWARD. OVERALL...MODELS INDICATE THE SFC PRESSURE PATTERN WILL YIELD AN E-SE WIND OVERNIGHT. THE NEAR-SHORE WATERS...SAY WITHIN 5 NM FROM THE COAST...MAY OBSERVE A NE WIND DIRECTION DURING THE MON PRE-DAWN HOURS. A RATHER RELAXED SFC PG WILL YIELD 10 KT OR LESS FOR SPEEDS. SIGNIFICANT SEAS GENERALLY AROUND 2 FT...EXCEPTION...ACROSS THE ILM SC WATERS WHERE AN ESE GROUNDSWELL..ALBEIT SMALL AND AT 9-10 SECOND PERIODS...COULD PUSH SIGNIFICANT SEAS UP TO 3 FEET. THIS GROUND SWELL IS COMPLEMENTS OF THE SOUTHERN PERIPHERY FETCH OF THE WESTERN ATLANTIC HIGH. SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 3 PM SUNDAY...MARINE REGIME MONDAY AND TUESDAY WILL SEE THE SW PORTION OF AN EXPANDING BERMUDA HIGH PRESSURE CELL MOVING ONTO THE COAST...WHILE A WEAK SURFACE COASTAL TROUGH PUSHES INLAND. THIS SHOULD IMPART A LIGHT S-SE WIND FLOW ACROSS THE 0-20NM WATERS. SEAS 2-3 FEET MOST AREAS...COMPOSED PRIMARILY OF SE WAVES EVERY 8-10 SECONDS WITH A LIGHT SOUTHERLY CHOP. WE MAY SEE A FEW SHOWERS AND TSTMS OVER THE WATERS EARLY MONDAY AS CONVERGENCE INCREASES IN RESPONSE TO THE COASTAL TROUGH ALONG THE COAST. NOT A BAD IDEA A GET A RADAR FIX MONDAY MORNING BEFORE HEADING OUT. LONG TERM /WEDNESDAY THROUGH FRIDAY/... AS OF 3 PM SUNDAY...THE FRONTAL BOUNDARY ALONG THE COAST CONTINUES THROUGH THE FIRST PART OF THIS FORECAST PERIOD. WITH A VERY WEAK PRESSURE GRADIENT EXPECTED WINDS WILL BE BE LESS THAN 10 KNOTS AND VARIABLE THROUGH THURSDAY MORNING. THE LOCAL WAVE MODEL COUPLED WITH THE WAVEWATCH III MODEL IS SHOWING SEAS AROUND 2 FEET THROUGH THURSDAY MORNING AND A SLIGHT INCREASE IN SEAS TO 2 TO 3 FEET BY LATE THURSDAY INTO FRIDAY AS A MORE SOUTH TO SOUTHWEST FLOW OF 10 KNOTS BECOMES ESTABLISHED. && .TIDES/COASTAL FLOODING... AS OF 1045 PM SUNDAY...THE TIDE GAGE ALONG THE CAPE FEAR RIVER PEAKED AT 5.74 FT MLLW AT HIGH TIDE THIS EVENING...ABOVE THE 5.50 FT MLLW MINOR COASTAL FLOODING THRESHOLD. THE GAGE READING IS NOW BELOW 5 FT MLLW AND CONTINUING TO DECLINE. WILL HAVE ANOTHER RUN AT BREACHING MINOR COASTAL FLOODING THRESHOLDS DURING MONDAY EVENINGS HIGH TIDE...WHICH MAY REQUIRE ANOTHER COASTAL HAZARD MESSAGE. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...MJC NEAR TERM...DCH SHORT TERM...MJC LONG TERM...DRH AVIATION...BJR/31 TIDES/COASTAL FLOODING...DCH
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
159 AM EDT MON AUG 19 2013 .SYNOPSIS... SEVERAL WEAK WEATHER SYSTEMS WILL DRIFT SLOWLY THROUGH THE GREAT LAKES FROM TONIGHT THROUGH MID-WEEK...AS TEMPERATURES AND HUMIDITY CONTINUE TO SLOWLY INCREASE AT THE SAME TIME. NEITHER OF THE DISTURBANCES IS EXPECTED TO BRING MUCH COVERAGE OF RAIN...BUT THREATS FOR SHOWERS OR A FEW THUNDERSTORMS ON A LIMITED BASIS WILL BE PRESENT TONIGHT INTO MONDAY MAINLY EAST OF I-71...AND ON WEDNESDAY ESPECIALLY SOUTH OF I-70. IN BOTH CASES...MOST AREAS WILL STAY DRY...WITH MUGGY AND WARM AFTERNOONS AND MILD NIGHTS WITH LIGHT WINDS. ABOVE NORMAL TEMPERATURES WILL REMAIN ENTRENCHED THROUGH THE WEEK INTO NEXT WEEKEND...AS A VERY TYPICAL LATE SUMMER PATTERN REMAINS IN PLACE. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... UPDATED TONIGHT TO REMOVE ALL PRECIPITATION FOR THE OVERNIGHT HOURS. WITH LOSS OF HEATING OF THE DAY AND WEAK FORCING REMAINING...THERE IS ONLY SMALL CHANCE OF SHOWERS. ALSO ADJUSTED SKY COVER FOR CURRENT TRENDS. NO OTHER SIGNIFICANT CHANGES WERE MADE WITH THIS UPDATE. AFTERNOON DISCUSSION FOLLOWS BELOW.... DISORGANIZED SHIELD OF VERY LIGHT RAIN/SPRINKLES HAS BEEN PUSHING STEADILY NORTHEAST THROUGH THE AFTERNOON UP THE SCIOTO RIVER VALLEY...IMMEDIATELY IN ADVANCE OF A MID-LEVEL VORTICITY MAX SEEN SWIRLING BOTH ON VISIBLE SATELLITE IMAGERY AND ON RADAR MOSAICS OVER NRN KENTUCKY. THIS IS NEAR THE NOSE OF A NARROW 250MB JETLET /115KT/ THAT IS SHIFTING NORTHEAST AND ALLOWING THE OPENING/SHEARING OF THE OLD CLOSED LOW THAT HAD BEEN SPINNING WELL SOUTHWEST OF THE AREA THE PAST FEW DAYS. THE MID/UPPER LEVEL SHORTWAVE TROUGH IS POSITIVELY TILTED...AND WEAKENING WITH TIME...WITH DECREASING LARGE SCALE ASCENT AND VERY WEAK SURFACE FEATURES UNDERNEATH. THE 18.18Z RAP HAD A NICE HANDLE ON THE MID LEVEL VORT MAX DRIVING NORTHEAST THROUGH SCNTL OH...AND CONTINUES TO LIFT THIS FEATURE OUT OF THE AREA THROUGH MID EVENING...WITH THE SHIELD OF LIGHT RAIN/SPRINKLES LIKELY EXITING THE AREA BY 00Z OR SO...IF IT DOESN/T FALL APART COMPLETELY BEFORE THEN. MESOANALYSIS CURRENTLY /19Z/ SHOWS A FAIRLY NICE DIFFERENTIAL HEATING ZONE /CAPE AXIS/ ON THE IMMEDIATE WEST SIDE OF THE RAIN SHIELD...RUNNING FROM OWEN/GRANT COUNTIES UP THROUGH THE WILMINGTON AREA TOWARDS CMH. VARIOUS AND SUNDRY CONVECTION ALLOWING MODEL RUNS /3-4KM RESOLUTION/ HAVE TRIED TO DEVELOP ISOLATED STORMS IN THIS CORRIDOR IN THE NEXT FEW HOURS UP THROUGH ABOUT 02Z...SO WE ARE IN NO HURRY TO DECREASE/SHRINK RAIN CHANCES WEST OR SOUTHWEST OF CURRENT RAIN SHIELD OVER SCNTL OH. WHILE MLCAPE IS LARGELY WEAK /300-700 J/KG/...THE PASSING OF THE MID/UPPER LEVEL PV ANOMALY ACROSS THIS AREA THROUGH THE NEXT FEW HOURS MAY AGITATE THE WEAK BAROCLINIC ZONE FOR A STORM OR TWO. LATER THIS EVENING/OVERNIGHT...ONE MORE SURGE /IF YOU CAN CALL IT THAT - IT IS QUITE WEAK/ OF MOISTURE ADVECTION RIDES FROM ERN TN/KY INTO CNTL/ERN OH AND MAY PROMOTE SOME -SHRA REGENERATION OVER THE SCIOTO VALLEY AND UP TOWARD/EAST OF CMH...SO WE HOLD ON TO HIGHER RAIN CHANCES HERE LATER THIS EVENING AND OVERNIGHT. NOT SURE IF THIS WILL LEAD TO MUCH ACTIVITY OR NOT...CONFIDENCE IS LOW...BUT THE SIGNAL HAS BEEN PRESENT FOR A FEW DAYS THUS DON/T WANT TO BACK AWAY YET. KEPT MIN TEMP FORECAST RIGHT WHERE IT WAS FOR THE MOST PART...WELL TRENDED IN THE LOWER 60S MOST AREAS...THOUGH MIXED OUT DEW POINTS IN WCNTL OHIO/ERN IND SUGGEST SOME MID TO UPPER 50S IN THAT AREA WHERE PRECIPITABLE WATER MINIMUM EXISTS. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... THE LAST WEAK SURGE OF MOISTURE MAY LINGER SHOWER CHANCES IN THE EAST IN THE MORNING...AND THERE MAY BE JUST ENOUGH DIURNAL INSTBY FOR A SHOWER/STORM IN THE FAR EAST/SOUTH IN THE AFTERNOON...BUT MONDAY IS LARGELY A DRY DAY FOR THE FORECAST AREA WITH INCREASING SUBSIDENCE IN THE WAKE OF THE DEPARTING SHORTWAVE TROUGH WHICH WILL BE SHEARING DOWNSTREAM THROUGH PA/NY. DESPITE ITS DEPARTURE...THERE REMAINS A WEAKNESS IN THE LARGER SCALE HEIGHT FIELD BETWEEN TWO LARGE ANTICYCLONES OFF THE SOUTHEAST CONUS AND OVER THE CNTL CONUS. THIS WEAKNESS IS A SOURCE OF LINGERING WEAK SHORTWAVE ENERGY...AND WITH THIS AXIS LINGERING IN THE FAR SOUTH/EAST...THUS THE SMALL RAIN CHANCES LINGERING UNTIL THAT AXIS CAN CLEAR IN THE MID AFTERNOON HOURS. MOST AREAS WILL SEE A FAIR AMOUNT OF SUNSHINE ON MONDAY...WITH TEMPS ADDING A FEW MORE DEGREES TO PUT MOST AREAS IN THE LOW-MID 80S. BRIEF SHORTWAVE RIDGING SLIDES IN FOR MONDAY NIGHT...WITH SKIES GOING CLEAR. THIS SHOULD ALLOW A LITTLE BETTER TEMP DROP WITH PWAT DROPPING OFF BACK TOWARD 1 INCH /BELOW SEASONAL NORMS/. THUS...SIDED WITH SOME OF THE MOS DATASETS THAT ALLOWED COOL SPOTS TO DROP OFF PRETTY DECENTLY MON NIGHT INTO THE UPPER 50S. WITH SUCH LIGHT WINDS OVER THE NEXT COUPLE NIGHTS...ALMOST CERTAIN TO BE COMMON SUMMER NIGHT FOG IN LOW LYING AREAS...BUT NOT SEEING A GREAT SIGNAL FOR SOMETHING WIDESPREAD TO INCLUDE IN THE FORECAST AS OF YET. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... SURFACE HIGH PRESSURE WILL ESTABLISH ITSELF TO OUR SE ON TUESDAY IN WAKE OF DEPARTING UPR LVL SYSTEM. WE SHOULD SEE A MOSTLY SUNNY TO PARTLY SUNNY DAY. MODELS HAD BEEN SUGGESTING THAT PERHAPS A POP OF SHOWER OR STORM COULD OCCUR IN THE FAR SOUTH DURING THE HEAT OF THE DAY. THIS STILL MAY OCCUR...BUT DO NOT FEEL IT WARRANTS A 20 POP MENTION SO HAVE ALLOW THE FORECAST TO REMAIN DRY. HIGHS WILL BE A LITTLE WARMER...GENERALLY IN THE MID 80S. FOR THE PERIOD TUESDAY NIGHT INTO WEDNESDAY NIGHT...MAJORITY OF MODELS HAVE COME MORE IN LINE ON WHAT WILL HAPPEN TO EMBEDDED S/WV ENERGY WITHIN THE NW FLOW ALOFT. IT APPEARS THIS ENERGY WILL DEVELOP INTO A CLOSED LOW TO OUR WEST...THEN WILL SLOWLY PROGRESS EAST THROUGH THE REGION WEDNESDAY INTO WEDNESDAY NIGHT. ECMWF/GFS SUGGEST THAT SOME EMBEDDED S/WV ENERGY MOVING NE AROUND DEVELOPING CLOSED LOW COULD SPARK A FEW SHOWERS AND THUNDERSTORMS BEGINNING ACRS OUR SW TUESDAY NIGHT. HAVE GIVEN ALL LOCATIONS AT LEAST A THREAT FOR SHOWERS AND STORMS ON WEDNESDAY WITH THE HIGHER CHANCES FAVORING THE SRN ZONES DUE TO HIGHER INSTABILITY AND MOISTURE. HAVE ALLOWED POPS TO FALL OFF OVERNIGHT WEDNESDAY NIGHT AS SYSTEM HEADS EAST. HIGHS ON WEDNESDAY WILL BE SLIGHTLY COOLER...ESPECIALLY SOUTHWEST CLOSER TO THE UPR LVL LOW. FOR THE PERIOD THURSDAY INTO FRIDAY NIGHT...MODELS CONTINUE TO STRUGGLE ON HOW LONG WAVE TROUGH ENERGY WILL DIG SE INTO SE CANADA AND NEW ENGLAND DURING THE PERIOD. AS SUCH...ASSOCIATED COLD FRONT AND WHERE IT WILL END UP...I.E. WILL IT PUSH THROUGH...STALL OUT OVER OUR AREA...OR PERHAPS FALL APART...IS STILL IN QUESTION. HAVE TAKEN A BLEND OF WPC AND THE LATEST 18.12Z ECMWF...WHICH ALLOWS THE FRONT TO APPROACH THE REGION FROM THE NORTH THURSDAY NIGHT...SLOW IT UP AS IT PUSHES INTO THE REMAINDER OF THE AREA ON FRIDAY...THEN WASHES IT OUT FRIDAY NIGHT INTO SATURDAY AS ANOTHER HIGH PRESSURE RIDGE BUILDS IN FROM THE NORTH. GIVEN LACK OF STRONG UPR SUPPORT...AS IT IS FCST TO REMAIN WELL OFF TO THE NE...ALONG WITH WEAK LOW LEVEL FORCING...HAVE KEPT POPS LOW THURSDAY NIGHT INTO FRIDAY. HAVE THEN ALLOWED CONDITIONS TO DRY OUT BY FRIDAY NIGHT. TEMPERATURES WILL BE CLOUD DEPENDENT BUT SHOULD SEE A SLIGHT BUMP UP AHEAD OF THE FRONT ON THURSDAY WITH SIMILAR OR SLIGHTLY COOLER CONDITIONS POSSIBLE ON FRIDAY. SURFACE HIGH PRESSURE WILL MOVE EAST THROUGH THE UPCOMING WEEKEND AS A MID LVL RIDGE BEGINS TO NUDGE INTO FROM THE CNTRL PLAINS. CONDITIONS SHOULD REMAIN DRY. TEMPERATURES WILL BE SEASONABLY WARM FOR LATE AUGUST. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... FOG AND IN SOME INSTANCES LOW CIGS HAVE DEVELOPED ACROSS THE AREA AND WILL CONTINUE THROUGH THE OVERNIGHT HOURS. EXPECT VSBYS TO FLUCTUATE THROUGH THE NIGHT HOWEVER CONDITIONS WILL IMPROVE SHORTLY AFTER SUNRISE. WINDS WILL BE LESS THAN 10 KNOTS THROUGH THE TAF PERIOD. ADDITIONAL FOG WILL BE POSSIBLE MONDAY NIGHT AS WELL. OUTLOOK...FOG WILL BE POSSIBLE MONDAY NIGHT. THUNDERSTORMS ARE POSSIBLE ON WEDNESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...BINAU NEAR TERM...BINAU/PARKER SHORT TERM...BINAU LONG TERM...HICKMAN AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
156 AM EDT MON AUG 19 2013 .SYNOPSIS... A WEAK DISTURBANCE WILL PASS ACROSS PA TODAY...BRINGING CLOUDS AND SOME RAIN. HIGH PRESSURE CENTERED NEAR BERMUDA WILL CONTROL THE WEATHER ACROSS PA DURING MIDWEEK...DELIVERING WARMER AND MORE HUMID CONDITIONS BEFORE A COLD FRONT ARRIVES AROUND FRIDAY. && .NEAR TERM /UNTIL 8 AM THIS MORNING/... UPPER LVL TROUGH LIFTING NE THRU THE OHIO VALLEY THIS AM. LG SCALE FORCING AHEAD OF THIS FEATURE IS RESULTING IN A FEW -SHRA ACROSS WESTERN PA AS OF 05Z AND EXPECT SCT -SHRA TO MOVE INTO THE ALLEGHENIES AND CENTRAL MTNS BY 12Z. CLOUD COVER AND INCREASING LOW LVL MOISTURE SHOULD KEEP TEMPS FROM FALLING MUCH FROM 05Z READINGS WITH LOWS IN THE M-U50S. && .SHORT TERM /8 AM THIS MORNING THROUGH 6 PM TUESDAY/... SLOW MOVING UPPER TROF WILL TAP 1.5" PW FOR MORE WIDESPREAD CHC OF SHOWERS AND TSTORMS ACROSS MOST AREAS ON MONDAY. PASSAGE OF UPPER TROF AXIS WILL BRING A DECREASING CHC OF SHOWERS ACROSS THE WESTERN COUNTIES DURING MID TO LATE AFTN. A GOOD DEAL OF CLOUD COVER SHOULD LIMIT CAPES...SO SEVERE WEATHER IS NOT EXPECTED. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... INTERESTING LOW OFF NORFOLK VA THIS AFT...STARTING TO PULL AREA OF SHOWERS EAST OF THE AREA THIS AFT...BUT MORE SHOWERS ACROSS THE OH VLY WITH THE UPPER LVL LOW. EXPECT SHOWERS TO LINGER INTO MONDAY...BEFORE CONDITIONS IMPROVE LATE. AFTER THIS...MAINLY DRY EXPECT FOR LATER THU INTO FRIDAY... WHEN A COLD FRONT MOVES ACROSS PA. SOME RISK OF SHOWERS ON WED ACROSS THE SE LIKE TODAY...BUT LEFT OUT FOR NOW. OVERALL A COMPLEX PATTERN...WITH THE TENDENCY FOR MORE STABLE AND LESS HUMID AIR TO TRY TO BUILD SOUTHWARD EAST OF THE MOUNTAINS... GIVEN HIGH OVER EASTERN CANADA AND NEW ENGLAND THIS WEEK. AT THE SAME TIME...WARMER AND MORE HUMID AIR WORKS NORTHWARD WEST OF THE MOUNTAINS. FOR NOW...LEFT MAX TEMPS CLOSE TO WHAT WAS IN THE GRIDS. REAL STRONG WARM ADVECTION WITH STRONG WESTERLY FLOW WILL BE WELL NORTH OF THE US...CANADIAN BORDER FROM LATE TUE INTO EARLY THU. MAIN CHANGE WAS TO UP MIN TEMPS MONDAY NIGHT AND TUE NIGHT...GIVEN GUIDANCE AND OTHER OFFICES. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... VERY SUBTLE FEATURES DRIVING THE FORECAST FOR THE NEXT 24 HOURS...AND THEREFORE FORECAST IS OF SOMEWHAT LOWER CONFIDENCE. VERY LITTLE PRECIPITATION REMAINS ON RADAR...AS WESTERN PA ACTIVITY HAS DWINDLED TO JUST A FEW SCATTERED SHOWERS. SHORT RANGE MODELS CONTINUE TO SUPPORT THE IDEA OF SHOWERS REDEVELOPING OVERNIGHT ACROSS THE WEST...AND SPREADING INTO CENTRAL PA BY MORNING. RUC ALSO CONTINUES THE THINKING OF DEVELOPING SCATTERED CONVECTION ACROSS CENTRAL AREAS TOMORROW AFTERNOON...PROPAGATING TO THE SOUTH AND EAST. HOWEVER...BASED ON RADAR TRENDS...HAVE CUT BACK ON PRECIPITATION IN MOST TAFS OVERNIGHT. FOG AND LOWER STRATUS FORECAST BY MODELS ALSO SLOWER THAN EXPECTED IN PREVIOUS FORECAST...WITH ALL LOCATIONS AT 03Z STILL VFR. WILL CONTINUE THE THINKING ALONG THE LINES OF LOWER CLOUDS AND FOG FORMATION...BUT HAVE BACKED OFF A BIT ON LOWER LIMITS OF RESTRICTIONS. UPPER TROF AXIS LIFTS NORTHEAST MONDAY. RESULT WILL BE SLIGHT SURFACE RIDGING DEVELOPING DURING THE DAY AND A SUBTLE/GRADUAL WIND SHIFT TO THE WEST DURING THE AFTERNOON. HOWEVER...REMNANTS OF UPPER TROF MOVING THROUGH THE REGION COULD DEVELOP SOME CONVECTION. WITHOUT A REAL PUSH OF DRIER AIR...EXPECT MORE FOG FORMATION MONDAY NIGHT INTO TUESDAY...BEFORE A RETURN TO VFR BY MID WEEK. OUTLOOK... MON...AM MVFR/IFR...WITH IMPROVEMENTS DURING THE AFTERNOON MOST LOCATIONS. ADDITIONALLY...SCATTERED SHOWERS AND ISOLATED TSRA. TUE...AM FOG POSS. THEN MAINLY VFR. WED-THU...VFR. FRI...MVFR WITH SCT SHRA/TSRA. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DEVOIR NEAR TERM...FITZGERALD SHORT TERM...DEVOIR/FITZGERALD LONG TERM...MARTIN AVIATION...JUNG
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
327 AM CDT MON AUG 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 327 AM CDT MON AUG 19 2013 THE MAIN FOCUS FOR TODAY IS ON A MID LEVEL TROUGH THAT WILL COME THROUGH AND WHETHER IT WILL HAVE ENOUGH LIFT TO OVERCOME THE DRY LOW LEVEL AIR AND PRODUCE SOME RAIN SHOWERS. THIS MID LEVEL TROUGH IS CURRENTLY ANALYZED VIA WATER VAPOR IR AND 19.06Z RAP 500MB ANALYSIS FROM SOUTHWESTERN ONTARIO THROUGH MINNESOTA AND EASTERN NEBRASKA. SOME VERY HIGH BASED RADAR RETURNS HAVE BEEN SHOWING UP ACROSS EASTERN SOUTH DAKOTA AND WESTERN MINNESOTA THOUGH THERE HAVE NOT BEEN MANY SIGHTS REPORTING THAT THE RAIN IS REACHING THE GROUND. THIS IS ALSO IN A BELT OF HIGHER LOW LEVEL MOISTURE TRANSPORT THAT IS TRAPPED UNDER A 700MB INVERSION...BUT IS HELPING TO RAISE SURFACE DEW POINTS. THIS IN TURN HAS CREATED A MORE UNSTABLE AIR MASS FROM THE DAKOTAS UP INTO NORTHERN MINNESOTA. THE 19.07Z RAP KEEPS MUCH OF THIS MOISTURE TRANSPORT AND HIGHER INSTABILITY OUT TO THE WEST TODAY...SO THIS TROUGH WILL BE ENTERING AN ENVIRONMENT THAT IS LESS FAVORABLE TO SEE THE SHOWERS CONTINUE. CONSIDERED PUTTING IN A MENTION OF SPRINKLES TODAY IN FOR SOUTHEAST MINNESOTA AND WESTERN TO NORTH CENTRAL WISCONSIN...BUT HELD OFF FOR THE TIME BEING SINCE REFLECTIVITIES OUT WEST APPEAR TO BE ON A WEAKENING TREND. MID TO HIGH LEVEL CLOUD COVER WILL BE FAIRLY WIDESPREAD FOR A PORTION OF THE DAY WHICH WILL KEEP TEMPERATURES DOWN A LITTLE BIT. THE 19.00Z NAM/GFS SHOW SOME WARMER 850/925MB AIR MOVING IN THIS AFTERNOON AS SOME OF THIS CLOUD COVER EXITS. EXPECT THAT WE WILL WARM UP PRETTY QUICKLY AS THIS OCCURS...BUT PERHAPS NOT AS HIGH AS PREVIOUSLY ADVERTISED. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 327 AM CDT MON AUG 19 2013 CONDITIONS WILL CONTINUE TO WARM INTO MID WEEK AHEAD OF A COLD FRONT/TROUGH THAT WILL PROPAGATE INTO THE REGION ON WEDNESDAY. WEDNESDAY IS EXPECTED TO BE THE WARMEST DAY OF THE WEEK WITH LOW LEVEL WARM AIR ADVECTION BUMPING 925MB TEMPERATURES UP TO AROUND 26C AND 850MB TEMPERATURES TO 20C. THIS WARM LAYER SHOULD ALSO HELP TO KEEP THE WARM SECTOR CAPPED OFF UNTIL THE COLD FRONT DROPS DOWN LATE WEDNESDAY AFTERNOON AND EVENING. THE AIR MASS WILL BECOME UNSTABLE WITH MODIFIED 19.00Z NAM/GFS SOUNDINGS...MODIFIED FOR LOWER DEW POINTS IN THE MID/UPPER 60S...SHOWING BETWEEN 1500-2500 J/KG OF 0-3KM MUCAPE ALONG A NARROW CORRIDOR JUST AHEAD OF THE FRONT. WIND SHEAR LOOKS MARGINAL WITH THE BETTER DEEP SHEAR IN CENTRAL MINNESOTA/NORTHERN WISCONSIN WHERE 500MB WINDS WILL BE AROUND 40KTS DUE TO THE MID LEVEL SHORT WAVE TROUGH DROPPING INTO THE NORTHERN GREAT LAKES. FURTHER SOUTHWEST ALONG THE FRONT CLOSER TO SOUTHERN MINNESOTA AND NORTHERN IOWA...19.00Z NAM/GFS SOUNDINGS/HODOGRAPHS DO SHOW SOME DIRECTIONAL/SPEED SHEAR IN THE LOWEST 2KM WHICH WOULD BE MORE FAVORABLE FOR STRONGER WINDS. BASED ON THE INSTABILITY AND SHEAR...IT APPEARS THAT LARGE HAIL AND DAMAGING WINDS STILL APPEAR TO BE THE MAIN THREATS IN THE LATE AFTERNOON INTO THE EVENING...PARTICULARLY ACROSS SOUTHEAST MINNESOTA...WESTERN WISCONSIN AND NORTHEAST IOWA. THE ISSUE THEN CONTINUES TO BE WITH HOW FAR SOUTH WILL THE COLD FRONT MAKE IT AND THEN HOW FAST DOES IT GET PUSHED BACK TO THE NORTH AS A WARM FRONT BY THE END OF THE WEEK. THE ECMWF HAS TRENDED TOWARD WHAT THE GFS/GEM HAVE BEEN ADVERTISING THE PAST FEW DAYS WITH HAVING THE FRONT DROP SOUTH INTO IOWA/NORTHERN ILLINOIS BY THURSDAY MORNING...BUT THE 19.00Z ECMWF STILL REMAINS THE FURTHEST NORTH WITH WHERE IT STALLS OUT. THERE ALSO IS BETTER CONTINUITY WITH THE NEXT TROUGH TRACKING ACROSS THE NORTHERN PLAINS ON FRIDAY INTO SATURDAY WHICH IS WHEN THE FRONT COMES BACK NORTH AS A WARM FRONT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1100 PM CDT SUN AUG 18 2013 A TIGHTENING PRESSURE GRADIENT IN PLACE THIS MORNING WILL HELP TO PRODUCE A DEEPER AND STRONGER LAYER OF WINDS...WITH SPEEDS OF 10-20 KTS FROM JUST RIGHT ABOVE THE SURFACE TO 5000 FT. THESE WINDS COMBINED WITH SOME PASSING CIRRUS SHOULD HELP KEEP RIVER VALLEY FOG TO A MINIMUM. HOWEVER...HAVE LEFT THE MVFR VISIBILITIES AND THE POTENTIAL FOR A SCATTERED 400 FT STRATUS DECK TO DEVELOP ALONG THE CHANNEL. IF WINDS DO NOT INCREASE AS FORECAST... VISIBILITIES AND CEILINGS COULD END UP A LOT LOWER. OTHERWISE... SCATTERED TO BROKEN HIGH LEVEL CLOUDS ASSOCIATED WITH A PASSING WEATHER SYSTEM TO THE NORTH WILL SPILL OVER THE TAF SITES. AFTERNOON CUMULUS WITH BASES BETWEEN 4 AND 5 KFT LIKELY AS WELL. MODEL SOUNDINGS SHOW MORE MIXING...ESPECIALLY ACROSS THE OPEN AREAS OF MINNESOTA...RESULTING IN THE NEED FOR GUSTS AT KRST FOR THE AFTERNOON. PLAN ON WINDS TO DIMINISH IN THE EVENING WITH LOSS OF HEATING...ALONG WITH CLEARING SKIES. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM...HALBACH AVIATION...ZT/AJ
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
1128 PM CDT SUN AUG 18 2013 UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE .SHORT TERM...TONIGHT AND MONDAY ISSUED AT 256 PM CDT SUN AUG 18 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE CENTERED OVER THE NE U.S...BUT WITH A RIDGE AXIS THAT EXTENDS WEST INTO THE GREAT LAKES. THE MAIN STORM TRACK REMAINS NORTH OF THE REGION OVER SOUTHERN CANADA...BUT IS GRADUALLY SINKING TO THE SOUTH. AS THIS OCCURS...A SHORTWAVE OVER EASTERN MONTANA IS MOVING EAST AND PRODUCING THUNDERSTORMS...WHICH WILL TRACK TOWARDS THE REGION TOMORROW. BESIDES TEMPERATURES...SMALL THUNDERSTORM CHANCES REMAIN THE MAIN FORECAST CONCERNS. TONIGHT...THE SHORTWAVE TROUGH OVER EASTERN MONTANA WILL MOVE EAST INTO THE NORTHERN MISSISSIPPI VALLEY BY 12Z MONDAY. THE 850MB MOISTURE AND INSTABILITY AXES WILL SHIFT INTO NORTHEAST MINNESOTA BY THIS TIME...WHICH LOOKS TOO FAR WEST FOR MUCH OF AN IMPACT ON THE FORECAST AREA. OTHERWISE...SCATTERED HIGH CLOUDS WILL BE PASSING OVERHEAD FOR MUCH OF NIGHT...AND THEN SEE THE HIGH CLOUDS THICKEN AND LOWER A BIT LATE AS THE SHORTWAVE DRAWS CLOSER. THE PRESSURE GRADIENT WILL BE TIGHTENING TONIGHT...WHICH SHOULD ALLOW A LIGHT SW WIND TO PERSIST AND KEEP ANY FOG FROM FORMING. LOWS WILL CONTINUE THEIR WARMING TREND...AND RESIDE IN THE 50S. MONDAY...THE SHORTWAVE TROUGH WILL MOVE INTO WISCONSIN. FORCING WITH THE WAVE APPEARS TO SUBTLY WEAKEN...SO WILL LIKELY NEED THE HELP OF DIURNAL INSTABILITY TO GET CONVECTION GOING. THE MOISTURE AXIS WILL BE SNEAKING INTO NORTH-CENTRAL WISCONSIN IN THE AFTERNOON...BUT PROGGED NAM SOUNDINGS AT 21Z NEAR EAGLE RIVER SHOW DECENT CAPPING CENTERED AT ABOUT 800 MB. USING A PARCEL OF 82/62...ML CAPES WILL REACH AROUND 1000 J/KG...WHILE CINS REMAIN A ROBUST 70-80 J/KG. UNLESS THE CAP IS ADVERTISED TOO STRONGLY...CANNOT SEE MORE THAN ISOLATED STORM DEVELOPMENT GIVEN THE WEAK FORCING. IF STORMS DO DEVELOP...WEAK SHEAR ALOFT WILL KEEP THE SEVERE THREAT RATHER LOW. MADE ONLY MINOR TWEAKS TO TIMING AND COVERAGE OF POPS. DESPITE AN INCREASE IN CLOUD COVER...LOW LEVEL TEMPS WILL ALSO BE WARMING...AND PUSH HIGHS INTO THE MIDDLE 80S. .LONG TERM...MONDAY NIGHT THROUGH SUNDAY ISSUED AT 256 PM CDT SUN AUG 18 2013 TUESDAY THROUGH NEXT WEEKEND WILL BE HIGHLIGHTED WITH ABOVE NORMAL TEMPERATURES. THE NEXT MAIN CHANCE FOR WIDESPREAD PRECIPITATION WILL BE STARTING WEDNESDAY AFTERNOON OVER NORTHWEST WISCONSIN THEN OVER THE REST OF THE STATE WEDNESDAY NIGHT INTO THURSDAY WITH THE PASSAGE OF A COLD FRONT. THERE IS A SMALLER CHANCE OF CONVECTION ON TUESDAY OVER THE NORTHWEST HALF OF THE STATE DUE TO CONTINUED WAA...AND IN A REGION OF UPPER DIVERGENCE AHEAD OF THE WESTERLIES OVER THE NORTHERN PLAINS. CONVECTION MAY BE CONFINED TOWARD WESTERN PORTION OF THE STATE BUT WILL LEAVE PARTS OF NC WI WITH SMALL CHANCE DUE TO TOTAL TOTALS INCREASE IN THE AFTERNOON. THE WESTERLY FLOW OVER THE NORTHERN PLAINS BEGINS TO BUCKLE WEDNESDAY AS A SHORT WAVE TROUGH DEVELOPS OVER SOUTHERN CANADA AND A COLD FRONT SAGS INTO THE NORTHERN GREAT LAKES REGION INCLUDING NORTHWEST WISCONSIN. MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT WITH THE TIMING OFF THIS FRONT AND CONVECTION UNTIL WEDNESDAY NIGHT FOR MOST LOCATIONS EXCEPT NORTH CENTRAL WISCONSIN. SEVERE POTENTIAL REMAINS FOR WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. TOTAL TOTALS CLIMB INTO THE LOWER 50S WITH THE FRONT WHILE PWATS INCREASE TO NEAR 2.00 GFS...GEM DROP THE CONVECTION AND FRONT WELL SOUTH ON THURSDAY FOR A DRIER TREND WHICH COULD LAST INTO FRIDAY. BUT THE ECMWF SLOWS THIS FRONT DOWN WHILE A HIGH PRESSURE SYSTEM DRIFTS OVER THE NORTHERN GREAT LAKES REGION THURSDAY THROUGH FRIDAY. THE UPPER RIDGE CONTINUES TO BUILD INTO THE WEEKEND FOR MORE HEAT ALONG WITH CHANCES OF CONVECTION ON THE PERIPHERY OF THE RIDGE OR MAINLY THE NORTHERN GREAT LAKES REGION. && .AVIATION...FOR 06Z TAF ISSUANCE ISSUED AT 1125 PM CDT SUN AUG 18 2013 VFR CONDITIONS EXPECTED AS ANTICYCLONE SLOWLY SHIFTS SE OF THE AREA. SHOULD SEE A LITTLE MORE GUSTINESS IN THE WINDS TOMORROW AS FAIRLY DEEP MIXING IS EXPECTED TO OCCUR. CAN/T RULE OUT A SHRA/TSRA ACRS THE N TOMORROW AFTN...BUT SUPPORT IS VERY LIMITED SO WL KEEP THE TAFS DRY. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
900 AM MDT MON AUG 19 2013 CORRECTION TO ADD MISSING WORD IN FIRST SENTENCE OF THE UPDATE .UPDATE... ISSUED AT 830 AM MDT MON AUG 19 2013 QUICK UPDATE TO THE GRIDDED FORECAST TO BETTER REFLECT THE CURRENT SUNNY/MOSTLY SUNNY CONDITIONS ACROSS MOST OF FORECAST AREA EARLY THIS MORNING. EXCEPTION IS SOME ALTOCUMULUS CLOUDS OVER SE UT LEFT OVER FROM LAST NIGHT AND WHERE THE RAP MODEL PUTS A WEAK VORTICITY MAX. CURRENT FORECAST FOR THIS AFTERNOON SEEMS ON TRACK PER QUICK LOOK AT THE LATEST RAP/HRRR MODELS. && .SHORT TERM...(TODAY THROUGH TUESDAY) 300 AM MDT MON AUG 19 2013 HIGH PRESSURE WILL REMAIN ANCHORED OVER THE REGION FOR THE NEXT SEVERAL DAYS. MOISTURE WORKING NORTHWARD WILL BRING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH THE FOCUS TODAY GENERALLY SOUTH OF INTERSTATE 70. STORMS WILL INITIALLY FIRE ALONG THE HIGHER TERRAIN...WITH ACTIVITY DRIFTING OFF OVER THE VALLEYS LATE THIS AFTERNOON AND EVENING...WITH AN EMPHASIS ON DRIFT. WINDS ALOFT WILL BE WEAK WITH THE RIDGE DIRECTLY OVERHEAD AND POTENTIAL FOR LOCALLY HEAVY RAINFALL WILL BE UP A BIT WITH SLOW STORM MOTIONS. TEMPERATURES WILL BE RUNNING NEAR SEASONAL NORMS WITH LIGHT WINDS OUTSIDE OF CONVECTIVE GUSTS TO NEAR 40 MPH WITH THE STRONGER STORMS. A STRONGER SURGE OF SUBTROPICAL MOISTURE CONTINUES TO WORK INTO THE GREAT BASIN AND THEN LEAKS EASTWARD INTO TUESDAY FOR AN UPTURN IN SHOWERS AND THUNDERSTORMS. THE SHEARED ENERGY FROM THE BAJA DISTURBANCE IS PROGGED TO STAY WELL WEST OF THIS CWA WITH TIME HEIGHT SECTIONS SHOWING LITTLE ORGANIZED DYNAMICAL LIFT. STILL PRECIPITABLE WATER VALUES CLIMB TO AN INCH OVER EASTERN UTAH AND FAR WESTERN COLORADO. BROKEN TO OVERCAST SKIES MAY LIMIT OR DELAY AFTERNOON HEATING AND INSTABILITY SOMEWHAT. SLOW STORM MOTION WILL PRODUCE LOCALLY HEAVY RAIN AND POTENTIAL RUNOFF PROBLEMS. A RELATIVELY DRY NEAR- SURFACE LAYER WILL ALSO ASSIST WITH ENHANCED LOCAL OUTFLOW WINDS. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) 300 AM MDT MON AUG 19 2013 BOUNDARY INTERACTION MAY PRODUCE ISOLATED NOCTURNAL CONVECTION INTO WEDNESDAY MORNING. THE 593 HIGH REBOUNDS WESTWARD BACK TO NEAR THE FOUR CORNERS. BOTH THE GFS AND NAM ERODE PRECIPITABLE WATER VALUES SOMEWHAT UNDER THE HIGH. SUBSIDENCE WILL ALSO CAP LATE DAY CONVECTION A BIT COMPARED TO TUESDAY. STILL ALL MTN RANGES WILL LIKELY FIRE SOME AFTERNOON STORMS. STORM MOTION REMAINS SLOW FOR A CONTINUED THREAT OF LOCALLY HEAVY SHOWERS. MOISTURE WORKING NORTHWARD ALONG THE WESTERN EDGE OF HIGH PRESSURE CENTERED ACROSS THE CENTRAL PLAINS WILL KEEP CONDITIONS UNSETTLED AS WE MOVE THROUGH THE WEEK AND INTO THE WEEKEND. HARD TO PIN POINT ANY INDIVIDUAL WAVE IN THIS PATTERN FOR ENHANCED POTENTIAL...SO FOR NOW WILL CONTINUE WITH THE BROAD BRUSH APPROACH OF DAILY CONVECTION...PRIMARILY FOCUSED ON THE AFTERNOON AND EVENING HOURS. TEMPERATURES WILL BE RUNNING NEAR SEASONAL NORMS THROUGH THE PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) 300 AM MDT MON AUG 19 2013 SCATTERED SHOWERS AND THUNDERSTORMS WILL AGAIN DEVELOP ACROSS EASTERN UTAH AND WESTERN COLORADO THIS AFTERNOON AND EVENING. THE STORMS WILL BE MOST NUMEROUS SOUTH AND EAST OF A LINE FROM K4HV TO KEGE...ESPECIALLY BETWEEN 20Z THIS AFTERNOON AND 03Z THIS EVENING. OUTSIDE OF THIS WINDOW...STORMS WILL BE MORE ISOLATED IN NATURE. EXPECT BRIEF HEAVY RAIN...SMALL HAIL AND GUSTY OUTFLOW WINDS TO 40 MPH IN THE VICINITY OF SHOWERS WITH BRIEF MOUNTAIN OBSCURATIONS POSSIBLE. STORMS DISSIPATE AFTER 03Z THIS EVENING WITH VFR CONDS PREVAILING AT ALL TERMINAL SITES. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...JAD SHORT TERM...JDC/JOE LONG TERM...JOE/JDC AVIATION...JDC
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
837 AM MDT MON AUG 19 2013 .UPDATE... ISSUED AT 830 AM MDT MON AUG 19 2013 QUICK UPDATE TO THE GRIDDED FORECAST TO BETTER REFLECT THE CURRENT SUNNY/MOSTLY CONDITIONS ACROSS MOST OF FORECAST AREA EARLY THIS MORNING. EXCEPTION IS SOME ALTOCUMULUS CLOUDS OVER SE UT LEFT OVER FROM LAST NIGHT AND WHERE THE RAP MODEL PUTS A WEAK VORTICITY MAX. CURRENT FORECAST FOR THIS AFTERNOON SEEMS ON TRACK PER QUICK LOOK AT THE LATEST RAP/HRRR MODELS. && .SHORT TERM...(TODAY THROUGH TUESDAY) 300 AM MDT MON AUG 19 2013 HIGH PRESSURE WILL REMAIN ANCHORED OVER THE REGION FOR THE NEXT SEVERAL DAYS. MOISTURE WORKING NORTHWARD WILL BRING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH THE FOCUS TODAY GENERALLY SOUTH OF INTERSTATE 70. STORMS WILL INITIALLY FIRE ALONG THE HIGHER TERRAIN...WITH ACTIVITY DRIFTING OFF OVER THE VALLEYS LATE THIS AFTERNOON AND EVENING...WITH AN EMPHASIS ON DRIFT. WINDS ALOFT WILL BE WEAK WITH THE RIDGE DIRECTLY OVERHEAD AND POTENTIAL FOR LOCALLY HEAVY RAINFALL WILL BE UP A BIT WITH SLOW STORM MOTIONS. TEMPERATURES WILL BE RUNNING NEAR SEASONAL NORMS WITH LIGHT WINDS OUTSIDE OF CONVECTIVE GUSTS TO NEAR 40 MPH WITH THE STRONGER STORMS. A STRONGER SURGE OF SUBTROPICAL MOISTURE CONTINUES TO WORK INTO THE GREAT BASIN AND THEN LEAKS EASTWARD INTO TUESDAY FOR AN UPTURN IN SHOWERS AND THUNDERSTORMS. THE SHEARED ENERGY FROM THE BAJA DISTURBANCE IS PROGGED TO STAY WELL WEST OF THIS CWA WITH TIME HEIGHT SECTIONS SHOWING LITTLE ORGANIZED DYNAMICAL LIFT. STILL PRECIPITABLE WATER VALUES CLIMB TO AN INCH OVER EASTERN UTAH AND FAR WESTERN COLORADO. BROKEN TO OVERCAST SKIES MAY LIMIT OR DELAY AFTERNOON HEATING AND INSTABILITY SOMEWHAT. SLOW STORM MOTION WILL PRODUCE LOCALLY HEAVY RAIN AND POTENTIAL RUNOFF PROBLEMS. A RELATIVELY DRY NEAR- SURFACE LAYER WILL ALSO ASSIST WITH ENHANCED LOCAL OUTFLOW WINDS. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) 300 AM MDT MON AUG 19 2013 BOUNDARY INTERACTION MAY PRODUCE ISOLATED NOCTURNAL CONVECTION INTO WEDNESDAY MORNING. THE 593 HIGH REBOUNDS WESTWARD BACK TO NEAR THE FOUR CORNERS. BOTH THE GFS AND NAM ERODE PRECIPITABLE WATER VALUES SOMEWHAT UNDER THE HIGH. SUBSIDENCE WILL ALSO CAP LATE DAY CONVECTION A BIT COMPARED TO TUESDAY. STILL ALL MTN RANGES WILL LIKELY FIRE SOME AFTERNOON STORMS. STORM MOTION REMAINS SLOW FOR A CONTINUED THREAT OF LOCALLY HEAVY SHOWERS. MOISTURE WORKING NORTHWARD ALONG THE WESTERN EDGE OF HIGH PRESSURE CENTERED ACROSS THE CENTRAL PLAINS WILL KEEP CONDITIONS UNSETTLED AS WE MOVE THROUGH THE WEEK AND INTO THE WEEKEND. HARD TO PIN POINT ANY INDIVIDUAL WAVE IN THIS PATTERN FOR ENHANCED POTENTIAL...SO FOR NOW WILL CONTINUE WITH THE BROAD BRUSH APPROACH OF DAILY CONVECTION...PRIMARILY FOCUSED ON THE AFTERNOON AND EVENING HOURS. TEMPERATURES WILL BE RUNNING NEAR SEASONAL NORMS THROUGH THE PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) 300 AM MDT MON AUG 19 2013 SCATTERED SHOWERS AND THUNDERSTORMS WILL AGAIN DEVELOP ACROSS EASTERN UTAH AND WESTERN COLORADO THIS AFTERNOON AND EVENING. THE STORMS WILL BE MOST NUMEROUS SOUTH AND EAST OF A LINE FROM K4HV TO KEGE...ESPECIALLY BETWEEN 20Z THIS AFTERNOON AND 03Z THIS EVENING. OUTSIDE OF THIS WINDOW...STORMS WILL BE MORE ISOLATED IN NATURE. EXPECT BRIEF HEAVY RAIN...SMALL HAIL AND GUSTY OUTFLOW WINDS TO 40 MPH IN THE VICINITY OF SHOWERS WITH BRIEF MOUNTAIN OBSCURATIONS POSSIBLE. STORMS DISSIPATE AFTER 03Z THIS EVENING WITH VFR CONDS PREVAILING AT ALL TERMINAL SITES. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...JAD SHORT TERM...JDC/JOE LONG TERM...JOE/JDC AVIATION...JDC
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1122 AM EDT MON AUG 19 2013 .SYNOPSIS... A HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH TUESDAY. A BROAD...WEAK TROUGH OF LOW PRESSURE WILL REMAIN OVER THE NORTHEASTERN U.S. TUESDAY NIGHT THROUGH WEDNESDAY NIGHT AS HIGH PRESSURE REMAINS CENTERED TO OUR SOUTH. A COLD FRONT APPROACHES FROM THE NORTHWEST THURSDAY...THEN CROSSES THE TRI-STATE THURSDAY NIGHT AND FRIDAY MORNING. HIGH PRESSURE THEN BUILDS IN FROM THE NORTHWEST FOR THE UPCOMING WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... SOMEWHAT COMPLICATED SCENARIO UNFOLDING THIS AFTERNOON/EVENING AS AN ANTICYCLONIC UPPER LEVEL JET STREAK MOVES ACROSS THIS AFTERNOON...FOLLOWED BY A MID LEVEL TROUGH THIS EVENING. THE JET STREAK IS INDUCING AN INCREASE IN HIGH CLOUDS ATTM...AND MID LEVEL CLOUDS SHOULD FOLLOW LATE THIS AFTERNOON AS WELL. SCT SHOWERS OVER CENTRAL/ERN PA MAY SNEAK IN TO FAR WRN SECTIONS...AND THERE APPEARS TO BE ENOUGH ELEVATED MUCAPE TO LEAVE IN A SLIGHT CHANCE MENTION OF THUNDER THERE. FARTHER EAST...SHOULD SEE SPRINKLES/SHOWERS OUT OF THE ADVANCING MID LEVEL CLOUD DECK. FORCING AND MOISTURE ADVECTION ARE DISJOINTED...WITH THE UPPER LEVEL JET STREAK OUTRUNNING OTHER LOWER LEVEL FEATURES...BUT HAVE SEEN THESE JET STREAKS OUTPERFORM MODEL EXPECTATIONS AND THINK LAST COUPLE OF RUNS OF THE RAP ARE POINTING IN THE RIGHT DIRECTION TO WARRANT SPATIAL/TEMPORAL EXTENSION OF AT LEAST SLIGHT CHANCE POP TO THE REST OF THE CWA...MAINLY THIS EVENING. AS THE MID LEVEL TROUGH EXITS...THE MID AND UPR LVL MOISTURE WILL FINALLY START TO BE SHUNTED S AND E OF THE CWA. THIS WILL RESULT IN CLEARING SKIES OVERNIGHT. && .SHORT TERM /TUESDAY/... MOSTLY SUNNY WITH BUILDING HEIGHTS AND WARMER TEMPS. WITH WEAK SUBSIDENCE THRU THE COLUMN...WILL CONTINUE DRY FCST. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... DEEP LAYERED RIDGING BUILDS OVER THE AREA TUESDAY NIGHT AND WEDNESDAY...WITH THE RIDGE AXIS PASSING TO THE EAST WEDNESDAY AFTERNOON AND NIGHT. DUE TO SUBSIDENCE UNDER THE RIDGE IT SHOULD BE DRY WITH MINIMAL CLOUD COVER. LOWS TUESDAY NIGHT SHOULD BE SLIGHTLY ABOVE NORMAL...CONSISTENT WITH A BLEND OF MAV/MET GUIDANCE. HIGHS WEDNESDAY WILL RUN 5-10 DEGREES ABOVE NORMAL...WITH THE POSSIBILITY OF LOCATIONS IN NYC AND URBAN NE NJ REACHING OR JUST GOING ABOVE THE 90 DEGREE MARK. THIS IS CONSISTENT WITH A BLEND OF MIXING DOWN FROM 850 HPA NEAR THE COAST AND 825 HPA INLAND...NAM 2-METER TEMPERATURES AND A BLEND OF MAV/MET GUIDANCE. FOR NOW IT APPEARS THAT HEAT INDICES WEDNESDAY AFTERNOON WILL NOT BE MUCH MORE THAN THE AIR TEMPERATURE...SO A HEAT ADVISORY IS NOT ANTICIPATED TO BE REQUIRED. USED A BLEND OF MEX/MEN/ECE/WPC GUIDANCE FOR LOWS WEDNESDAY NIGHT WITH VALUES A FEW DEGREES ABOVE NORMAL FORECAST. SW FLOW ALOFT ON THURSDAY WITH A PASSING SHORTWAVE...THEN A 700-500 HPA TROUGH CROSSES THE AREA THURSDAY NIGHT AND FRIDAY. FOR NOW LEANED TOWARDS FASTER ECMWF/CMC OVER SLOWER GFS WITH THE TROUGH (THOUGH CONVERSELY SLOWER ECMWF/CMC FRONTAL TIMING VICE FASTER GFS). AS A RESULT...LIMIT POPS TO SLIGHT CHANCE THURSDAY OVER WESTERN ZONES TO REFLECT THE POTENTIAL FOR SHRA/TSTM WITH PASSING SHORTWAVE AND THE DEVELOPMENT OF A PRE-FRONTAL TROUGH. GO WITH CHANCE POPS AHEAD OF THE FRONT/MID-UPPER TROUGH THURSDAY NIGHT...AS IT APPEARS DYNAMICS SHOULD BE SUFFICIENT TO OVERCOME MEAGER CAPE. HOWEVER...GIVEN MEAGER CAPE...DID RESTRICT CHANCE OF THUNDER THURSDAY NIGHT TO SLIGHT CHANCE. THE FRONT SHOULD FINISH MOVING THROUGH PRETTY QUICKLY FRIDAY MORNING...SO ONLY HAVE SLIGHT CHANCE POPS ACROSS THE NORTHERN TIER IN RESPONSE TO PASSING OF 700-500 HPA TROUGH AXIS. NW FLOW ALOFT IN THE WAKE OF THE DEPARTING TROUGH FRIDAY NIGHT-SUNDAY. FOR NOW BELIEVE GFS IS TOO PROGRESSIVE - AS IT OFTEN IS IN THE EXTENDED - IN BUILDING IN THE RIDGE AXIS FROM THE SPRAWLING 500 HPA RIDGE FORECAST TO BE OVER THE MIDDLE PART OF THE COUNTRY NEXT WEEKEND. SO DO NOT THINK IT WILL GET QUITE AS WARM AS THE GFS WOULD SUGGEST. NOTING NO SHORTWAVES/MCS CURRENTLY FORECAST HAVE GONE DRY SATURDAY-SUNDAY - HOWEVER THIS PATTERN IF THE FORECAST BEARS OUT IS CONDUCIVE TO MCS DIVING DOWN FROM THE GREAT LAKES SO WILL NEED TO MONITOR. FOR TEMPERATURES THURSDAY-SUNDAY USED A BLEND OF MEX/MEN/ECE/WPC GUIDANCE. TEMPERATURES START OUT ABOVE NORMAL AHEAD OF THE FRONT...BUT RETURN TO NEAR TO SLIGHTLY BELOW NORMAL LEVELS FOR THE WEEKEND BEHIND THE FRONT. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... VFR FOR THE PERIOD. W TO SW FLOW THROUGH THIS AFTERNOON WITH WIND GENERALLY BETWEEN 5 AND 10 KT. WINDS BECOME LIGHT AFTER 02/03Z THIS EVENING. SEA BREEZE DEVELOPMENT EXPECTED TODAY. SCT-BKN MID AND HIGH LEVEL CLOUDS...SCATTERING OUT LATER TONIGHT. LOW CONFIDENCE OF LIGHT RAIN SHOWERS MAINLY WEST AND NORTH OF NYC LATE AFTN...NOT INCLUDING IN TAFS WITH MINIMAL IMPACT ON CIGS/VIS. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KJFK FCSTER COMMENTS: SEA BREEZE BETWEEN 16 AND 18Z...GENERALLY SSW FLOW AROUND 12 KT. OCCASIONAL GUSTS UP TO 16 KT AFTN. KLGA FCSTER COMMENTS: LOW CONFIDENCE OF SEA BREEZE. W FLOW WITH OCCASIONAL GUSTS UP TO 15 KT THIS AFTN. KEWR FCSTER COMMENTS: W FLOW WITH PSBL GUSTS UP TO 15 KT THIS AFTN. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KTEB FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KHPN FCSTER COMMENTS: NO UNSCHEDULED AMENDMENTS EXPECTED. KISP FCSTER COMMENTS: MOD CONFIDENCE ON SEA BREEZE BETWEEN 16 AND 18Z. OUTLOOK FOR 12Z TUESDAY THROUGH FRIDAY... .TUE-WED...VFR. .THU...CHC SUB-VFR IN SHOWERS/TSTM. .FRI...VFR. && .MARINE... HIGH PRESSURE CENTERED SW OF THE WATERS WILL KEEP WINDS AND SEAS BELOW SCA LEVELS THROUGH TUE. WINDS/SEAS E OF MORICHES INLET IN LONGER FETCH WSW FLOW MAY HOWEVER GET CLOSE TO SCA LEVELS THIS AFTERNOON. A RELATIVELY RELAXED PRESSURE GRADIENT OVER THE REGION TUESDAY NIGHT-FRIDAY WILL KEEP WINDS 10 KT AND SEAS TO 3 FT OR LESS OVER THE COASTAL OCEAN WATERS AND TO 1 FT OR LESS OVER THE REMAINDER OF THE WATERS AROUND LONG ISLAND. && .HYDROLOGY... ORGANIZED RAINFALL IS NOT EXPECTED THROUGH TUE. IT SHOULD THEN BE DRY THOUGH THE MIDDLE OF THE WEEK. && .EQUIPMENT... THE NOAA ALL HAZARDS WEATHER RADIO TRANSMITTER IN NEW YORK CITY HAS BEEN DE-ACTIVATED UNTIL FURTHER NOTICE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. NJ...NONE. MARINE...NONE. && $$ SYNOPSIS...JMC/MALOIT NEAR TERM...JMC SHORT TERM...JMC LONG TERM...MALOIT AVIATION...BC/SEARS MARINE...JMC/MALOIT HYDROLOGY...JMC/MALOIT
AREA FORECAST DISCUSSION
NWS ALBANY NY
1037 AM EDT MON AUG 19 2013 .SYNOPSIS... DRY WEATHER IS EXPECTED TO CONTINUE INTO THE MID WEEK PERIOD WITH WARMING TEMPERATURES...AS HIGH PRESSURE REMAINS IN PLACE ACROSS OUR REGION. A COLD FRONT IS EXPECTED TO DROP SOUTHEAST FROM THE UPPER GREAT LAKES AND SOUTHEAST CANADA BRINGING A CHANCE OF SHOWERS AND THUNDERSTORMS LATE THURSDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1037 AM EDT...MORNING FOG HAS BURNED OFF ACROSS THE REGION. WHILE THE ADIRONDACKS ARE NEARLY CLEAR...A BAND OF MID AND HIGH LEVEL CLOUDS IS STREAMING NORTHEASTWARD ACROSS THE CATSKILLS...CAPITAL REGION...AND INTO SRN VT AND THE BERKSHIRES. THESE CLOUDS...ASSOCIATED WITH A SHORTWAVE TROUGH OVER PA AND A 100+ KT JET STREAK OVER THE NORTHEAST...WILL CONTINUE FOR THE NEXT SEVERAL HOURS. THE TROUGH WILL BEGIN TO SHEAR OUT BY LATER TODAY...AND THE BEST BAND OF CLOUDS WILL BEGIN TO SHIFT SOUTH AND EAST OF THE REGION...ALLOWING FOR SOME IMPROVEMENT IN THE SKY COVER...WITH MOST AREAS PARTLY CLOUDY BY LATER THIS AFTERNOON. ANY LIGHT SHOWERS WITH THIS SHORTWAVE SHOULD REMAIN SOUTH OF THE AREA ACROSS PA AND NJ...SO NO POPS ACROSS OUR REGION TODAY. THE LATEST 12Z LOCAL HIRES WRF AND 3KM HRRR ALL AGREE THAT WE SHOULDN/T HAVE ANY SHOWERS IN OUR AREA TODAY AS WELL...WITH THE BEST MOISTURE/FORCING TO THE SOUTH. WITH CLOUDS EXPECTED TO CLEAR OR THIN OUT...WE STILL APPEAR ON TRACK FOR MAX TEMPS IN THE UPPER 70S TO LOW 80S ACROSS LOWER TERRAIN PORTIONS OF THE AREA. THE HILLS AND MTNS WILL SEE MAX TEMPS RANGING FROM THE UPPER 60S TO THE MID 70S. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... TRANQUIL WEATHER IS EXPECTED THROUGH THE PERIOD WITH WARMING TEMPERATURES AND SLOWLY RISING HUMIDITY LEVELS. OUR REGION WILL BE UNDER THE INFLUENCE OF SURFACE HIGH PRESSURE...WITH UPPER LEVEL HEIGHTS GRADUALLY RISING THROUGH THE PERIOD AS WELL. SO DESPITE STRONG SURFACE HEATING...CONVECTION IS NOT EXPECTED SINCE UPPER LEVEL TEMPERATURES WILL BE QUITE WARM /AROUND -7C AT 500 MB TUESDAY INTO WEDNESDAY/. WITH THE WARMING ALOFT...MAX TEMPS ON TUESDAY ARE EXPECTED TO REACH THE MID 80S IN MOST VALLEY LOCATIONS WITH UPPER 80S ON WEDNESDAY. OVERNIGHT LOWS ARE EXPECTED TO BE ABOVE NORMAL AS WELL...ESPECIALLY TUESDAY NIGHT AND WEDNESDAY NIGHT WHEN THE WARMEST AIR ALOFT WILL BE OVER THE REGION. LATE NIGHT/EARLY MORNING PATCHY FOG WILL BE COMMON IN FAVORED AREAS AGAIN...ESPECIALLY TONIGHT AND TUESDAY NIGHT. && .LONG TERM /THURSDAY THROUGH SUNDAY/... MAINLY DRY WEATHER IS EXPECTED DURING THE LONG TERM PERIOD EXCEPT FOR LATE THURSDAY INTO THURSDAY EVENING WHEN SHOWERS AND THUNDERSTORMS ARE POSSIBLE ESPECIALLY NORTHERN AREAS AHEAD OF A COLD FRONT DROPPING SOUTHEASTWARD THROUGH THE FA. WHILE THERE IS LIMITED MOISTURE TO WORK WITH AHEAD OF THE COLD FRONT...SHOWALTER INDICES ARE SLIGHTLY NEGATIVE AND SB CAPES RISE BRIEFLY TO BTWN 500 AND 1000 J/KG. WL HAV CHANCE POPS ACRS THE SRN ADIRONDACKS AND LAKE GEORGE REGION AND SLIGHT CHANCE POPS ELSEWHERE LATE THURSDAY. FRIDAY THROUGH SUNDAY EXPECT MAINLY DRY CONDITIONS...ALTHOUGH WIDELY SCATTERED SHOWERS ARE POSSIBLE ON FRIDAY WITH THE UPPER TROF AXIS CROSSING THE FA. TEMPS ARE EXPECTED TO BE VERY WARM AHEAD OF THE FRONT ON THURSDAY FOLLOWED BY A GRADUAL COOL DOWN HEADING INTO THE WEEKEND IN THE WAKE OF THE COLD FRONT. HIGHS ON THURSDAY ARE EXPECTED TO BE IN THE 80S TO AROUND 90 WITH MID 70S TO MID 80S ON FRIDAY...70S TO AROUND 80 ON SATURDAY AND MID 70S TO LOWER 80S ON SUNDAY. LOWS WILL BE IN THE MID 50S TO MID 60S THURSDAY NIGHT AND 50S TO AROUND 60 FRIDAY NIGHT AND SATURDAY NIGHT. && .AVIATION /15Z MONDAY THROUGH FRIDAY/... ANY AREAS OF FOG AND ASSOCIATED IFR CONDITIONS SHOULD LIFT/BECOME VFR BY 13Z...WITH VFR CONDITIONS THEN PREVAILING THROUGH THE DAY MONDAY. A RETURN TO IFR CONDITIONS IS HIGHLY LIKELY AGAIN THIS EVENING AT KGFL AND KPSF WITH MVFR CONDITIONS POSSIBLE LATE TONIGHT AT KALB AND KPOU. LIGHT/VARIABLE WINDS WILL BECOME WEST TO SOUTHWEST AT 5-10 KTS BY THIS AFTERNOON AND THEN LIGHT AND VARIABLE THIS EVENING. OUTLOOK... TUESDAY-WEDNESDAY NIGHT: NO OPERATIONAL IMPACT. NO SIG WX. THURSDAY-THURSDAY NIGHT: MODERATE OPERATIONAL IMPACT. CHANCE OF SHRA...TSRA. FRIDAY: LOW OPERATIONAL IMPACT. SLIGHT CHANCE OF SHRA. && .FIRE WEATHER... NO FIRE WEATHER RELATED ISSUED ARE EXPECTED THROUGH THE PERIOD. MINIMUM RELATIVE HUMIDITY VALUES WILL RANGE FROM AROUND 40 TO 50 PERCENT THIS AFTERNOON...WITH FULL RECOVERY TO BETWEEN 95 AND 100 PERCENT TONIGHT WITH DEW FORMATION. RH VALUES WILL DROP TO AROUND 35 TO 45 PERCENT TUESDAY AFTERNOON. WINDS WILL BE WESTERLY AT 5 TO 10 MPH TONIGHT...BECOMING LIGHT AND VARIABLE TONIGHT. WINDS ON TUESDAY WILL ONCE AGAIN BE WESTERLY AROUND 5 TO 10 MPH. && .HYDROLOGY... DRY WEATHER IS EXPECTED TO CONTINUE THROUGH THE MIDDLE OF THE WEEK...WITH RIVER LEVELS NEAR NORMAL FOR MID TO LATE AUGUST. THE NEXT CHANCE OF ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARRIVES LATE THURSDAY ASSOCIATED WITH A COLD FRONT. THE PRECIPITATION IS NOT EXPECTED TO BE WIDESPREAD AND SHOULD HAVE MINIMAL IMPACT ON MAIN STEM RIVERS. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...JPV NEAR TERM...FRUGIS SHORT TERM...JPV LONG TERM...11 AVIATION...11 FIRE WEATHER...JPV HYDROLOGY...JPV
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
1033 AM EDT MON AUG 19 2013 .SYNOPSIS... A STATIONARY FRONT OVER THE AREA WILL DISSIPATE AS HIGH PRESSURE BUILDS WEST ACROSS THE AREA MID TO LATE WEEK. A WEAK TROUGH OF LOW PRESSURE WILL APPROACH FROM THE NORTHWEST THIS WEEKEND...FOLLOWED BY HIGH PRESSURE INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LATE MONDAY MORNING...ONGOING FORECASTS REMAINED ON TRACK AND REQUIRED ONLY MINOR ADJUSTMENTS. RAISED POPS BY 10-20 PERCENT ACROSS SC/INLAND COUNTIES..CERTAINLY NOT A MAJOR CHANGE BUT STILL SUFFICIENT TO GENERATE LIKELY POPS CLOSE TO THE CONVERGENCE AXIS ON THE PERIPHERY OF THE WEDGE STILL IN PLACE N/NW OF THE REGION. SOUTHEAST GEORGIA AND SOUTHERN SOUTH CAROLINA WILL REMAIN IN THE NW FLANKS OF THE ATLC SUBTROPICAL RIDGE TODAY. THE DEPARTING UPPER TROUGH FROM THE OHIO VALLEY TO THE MID SOUTH REGION IS PROGGED TO LIFT OUT TO THE NE INTO NEW ENGLAND BY LATE DAY. THE TAIL OF THE MID LEVEL VORT WILL INDUCE SOME VERY WEAK HEIGHT FALLS OVER THE INLAND CAROLINAS TODAY WHILE DEEP MID SUMMER MOISTURE PERSISTS REGION-WIDE. THE OLD WEDGE FRONT WILL CONTINUE TO DECAY OVER THE CAROLINAS TODAY. MODIFIED 12Z SOUNDINGS AND 00Z-06Z MODEL PROGS SUGGEST AN ACTIVE CONVECTIVE REGIME TODAY FEATURING EXPANDING COVERAGE OF SHOWERS/ THUNDERSTORMS. POPS ARE GRADUATED FROM HIGH CHANCE/LIKELY ACROSS INLAND COUNTIES OF SC/GA AND SC COUNTIES FROM COLLETON COUNTY EAST THROUGH COASTAL LOCATIONS TO 30-40 PERCENT ACROSS FROM JASPER COUNTY S/SW THROUGH AREAS ALONG/SOUTH OF I-16 INCLUDING THE SAVANNAH VICINITY. BEST COVERAGE WILL OCCUR SOME OF OUR INLAND AREAS COULD SEE SOME VERY HEAVY DOWNPOURS IN DEEP CONVECTION THIS AFTERNOON. THE 12Z HRRR INDICATES A COMPLEX MESOSCALE ENVIRONMENT FEATURING NUMEROUS BOUNDARIES INCLUDING THE SE BREEZE...THE INLAND TROUGH AND OUTFLOW BOUNDARIES. THUS...EXPECT SOME REPEATING SHOWERS/ THUNDERSTORMS WITH LOCALLY HEAVY CONVECTIVE RAINS ESPECIALLY N OF I-16 AND INLAND FROM U.S. 17 WHERE THE SUBTLE MID LEVEL HEIGHT FALLS OCCUR. WILL CONTINUE TO HIGHLIGHT A RISK FOR LOCALLY HEAVY DOWNPOURS AND MINOR TEMPORARY FLOODING CONCERNS FOR OUR NW INLAND ZONES IN OUR HAZARDOUS WEATHER OUTLOOK. THIS IS MAINLY IN RESPECT TO THE SOGGY SOIL CONDITIONS AND ONGOING RIVER FLOODING PLUS SWOLLEN TIDAL CREEKS WITH THE FULL MOON CYCLE. WE RAISED HIGH TEMPS A DEGREE OR SO IN SOME AREAS AS GUIDANCE IS RUNNING TOO COOL NOW THE WEDGE TO GONE. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/... TUESDAY THROUGH THURSDAY...A TYPICAL SUMMERTIME PATTERN WILL EVOLVE OVER THE SOUTHEASTERN UNITED STATES AS ATLANTIC HIGH PRESSURE EXPANDS OVER THE AREA THROUGH MIDWEEK. AS THIS OCCURS...DEEPEST MOISTURE WILL SHIFT INLAND AND WILL BE THE MAIN SOURCE OF PRECIP ACTIVITY EACH AFTERNOON WHILE WEAK H5 SHORTWAVES PASS OVERHEAD. DESPITE THE INLAND SHIFT OF DEEPEST MOISTURE...LIGHT ONSHORE FLOW WILL SUPPORT PWATS BETWEEN 1.5 TO 2 INCHES AS WELL AS SCATTERED SHOWERS AND/OR THUNDERSTORMS OVER SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA. HOWEVER...EXPECT MOST SHOWERS/THUNDERSTORMS TO GRADUALLY SHIFT INLAND BY EARLY AFTERNOON EACH DAY ALONG OR AHEAD A SEABREEZE. OVERALL HIGH TEMPS SHOULD RANGE IN THE UPPER 80S TO AROUND 90 EACH AFTERNOON. OVERNIGHT LOWS WILL RANGE IN THE LOW 70S INLAND TO MID/UPPER 70S ALONG THE COAST. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... A TYPICAL SUMMERTIME PATTERN WILL PERSIST THROUGH LATE WEEK AS ATLANTIC HIGH PRESSURE REMAINS OVER THE SOUTHEAST. CONDITIONS SHOULD REMAIN SOMEWHAT DRYER THROUGH FRIDAY WITH WEST/SOUTHWEST FLOW ALOFT. HIGH PRESSURE WILL THEN GRADUALLY RETREAT SOUTH AND EAST INTO THE WEEKEND AS A WEAK TROUGH OF LOW PRESSURE APPROACHES FROM THE NORTHWEST. A SLIGHT CHANCE OF SHOWERS AND/OR THUNDERSTORMS WILL BE POSSIBLE EACH DAY...WITH POSSIBLY INCREASING CHANCES ON SUNDAY BEFORE SFC HIGH PRESSURE AND DRYER MID LVL AIR SHIFTS OVER THE SOUTHEAST INTO EARLY NEXT WEEK. OVERALL HIGH TEMPS SHOULD RANGE IN THE UPPER 80S TO LOWER 90S EACH AFTERNOON...HIGHEST OVER INLAND AREAS IN SOUTHEAST GEORGIA. OVERNIGHT LOW TEMPS SHOULD RANGE IN THE LOW 70S INLAND TO LOW/MID 70S ALONG THE COAST. && .AVIATION /14Z MONDAY THROUGH FRIDAY/... SHOWER/TSTM COVERAGE WILL INCREASE TODAY...AND THE POTENTIAL FOR DIRECT IMPACTS AT TERMINALS WILL INCREASE. HOWEVER...ASIDE FROM OCCASIONAL SHOWERS WHICH WILL IMPACT KCHS THROUGH EARLY AFTERNOON PRECISE TIMING OF SHOWERS/TSTMS AND ASSOCIATED IMPACTS WILL BE INCLUDED WITHIN AMENDMENTS...WITH VCTS OTHERWISE INDICATED UNTIL AROUND 00Z. OUTSIDE PRECIPITATION...MAINLY VFR CONDITIONS WILL PREVAIL...WITH ONLY A LOW PROBABILITY FOR FLIGHT RESTRICTIONS LATE TONIGHT/EARLY TUESDAY. EXTENDED AVIATION OUTLOOK...VFR CONDITIONS ARE EXPECTED TO PREVAIL TUESDAY THROUGH SATURDAY AS HIGH PRESSURE PERSISTS OVER THE SOUTHEAST. BRIEF MVFR CIGS/VSBYS ARE POSSIBLE EACH AFTERNOON WITH INLAND MOVING SHOWERS AND/OR THUNDERSTORMS. && .MARINE... ATLC HIGH PRES WILL BE THE MAIN PLAYER FOR THE WATERS. MAINLY A S TO SE FLOW 10 KT OR LESS THROUGH TONIGHT WITH SEAS 2 TO 3 FT. HIGHER WINDS/SEAS COULD DEVELOP LOCALLY WITHIN/NEAR LOCALIZED SHOWERS/TSTMS. TUESDAY THROUGH FRIDAY...WINDS/SEAS ARE EXPECTED TO REMAIN WELL BELOW SMALL CRAFT ADVISORY LEVELS THROUGH LATE WEEK WITH HIGH PRESSURE DOMINATING THE WATERS. IN GENERAL...SOUTH TO SOUTHEAST WINDS WILL REMAIN AT OR BELOW 10-12 KT...HIGHEST NEAR SEABREEZE CIRCULATIONS ALONG THE COAST. SEAS WILL REMAIN AT OR BELOW 3 FT...HIGHEST IN OUTER GEORGIA WATERS. WATERSPOUTS...IT IS LOOKING DECENT THIS MORNING GIVEN INSTABILITY AND LIGHT CHAOTIC WIND FIELDS. WILL BE WAITING FOR SUNRISE TO SPOT CU LINES AND LAND BREEZE BOUNDARIES BEFORE ISSUING ANY MARINE WEATHER STATEMENTS. RIP CURRENTS...A SLIGHT INCREASE IN SWELLS COULD LEAD TO A MODERATE RISK OF RIPS BY MID WEEK. LOW RISK AT AREA BEACHES TODAY. && .TIDES/COASTAL FLOODING... GIVEN THE PERIGEAN SPRING TIDES...ADDITIONAL COASTAL FLOOD ADVISORIES ARE POSSIBLE THROUGH MID-WEEK WITH THE EVENING HIGH TIDE CYCLE. THIS EVENINGS HIGH TIDE SHORTLY BEFORE SUNSET COULD PRODUCE SHALLOW COASTAL FLOODING IN DOWNTOWN CHARLESTON AND FORT PULASKI ONCE AGAIN. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM...SPR SHORT TERM...DPB LONG TERM...DPB AVIATION...SPR MARINE...DPB/SPR TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
732 AM EDT MON AUG 19 2013 .SYNOPSIS... A STATIONARY FRONT OVER THE AREA WILL DISSIPATE AS HIGH PRESSURE BUILDS WEST ACROSS THE AREA MID TO LATE WEEK. A WEAK TROUGH OF LOW PRESSURE WILL APPROACH FROM THE NORTHWEST THIS WEEKEND...FOLLOWED BY HIGH PRESSURE INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... SOUTHEAST GEORGIA AND SOUTHERN SOUTH CAROLINA WILL REMAIN IN THE NW FLANKS OF THE ATLC SUBTROPICAL RIDGE TODAY. THE DEPARTING UPPER TROUGH FROM THE OHIO VALLEY TO THE MID SOUTH REGION IS PROGGED TO LIFT OUT TO THE NE INTO NEW ENGLAND BY LATE DAY. THE TAIL OF THE MID LEVEL VORT WILL INDUCE SOME VERY WEAK HEIGHT FALLS OVER THE INLAND CAROLINAS TODAY WHILE DEEP MID SUMMER MOISTURE PERSISTS REGION-WIDE. THE OLD WEDGE FRONT CONTINUES TO DECAY OVER THE CAROLINAS TODAY. FORECAST SOUNDINGS AND 00Z MODEL PROGS INDICATE POTENTIAL FOR SCATTERED CONVECTIVE RAINS TO DEVELOP OVER PORTIONS THE AREA BY MID MORNING ONCE THE LAND MASS BEGINS TO QUICKLY WARM AND ESPECIALLY SINCE SATELLITE IMAGERY SHOWS STRONG POTENTIAL FOR DIFFERENTIAL HEATING WITH I-95 THE DIVIDING LINE. CHANCE POPS ARE EXPECTED TO SPREAD INLAND THIS AFTERNOON WITH MANY AREAS ALONG AND W OF U.S. 17 EXPECTED TO SEE SCATTERED SHOWERS AND TSTMS. SOME OF OUR INLAND AREAS COULD SEE SOME VERY HEAVY DOWNPOURS IN DEEP CONVECTION THIS AFTERNOON. THE LATEST 3KM RAP MODEL INDICATES A PRETTY COMPLEX MESOSCALE AND THUS EXPECT SOME LOCALLY HEAVY CONVECTIVE RAINS WILL DEVELOP N OF I-16 AND INLAND FROM U.S. 17 WHERE THE SUBTLE MID LEVEL HEIGHT FALLS OCCUR. WE WILL HIGHLIGHT A RISK FOR LOCALLY HEAVY DOWNPOURS AND MINOR TEMPORARY FLOODING CONCERNS FOR OUR NW INLAND ZONES IN OUR HAZARDOUS WEATHER OUTLOOK. THIS IS MAINLY IN RESPECT TO THE SOGGY SOIL CONDITIONS AND ONGOING RIVER FLOODING PLUS SWOLLEN TIDAL CREEKS WITH THE FULL MOON CYCLE. WE RAISED HIGH TEMPS A DEGREE OR SO IN SOME AREAS AS GUIDANCE IS RUNNING TOO COOL NOW THE WEDGE TO GONE. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... TUESDAY THROUGH THURSDAY...A TYPICAL SUMMERTIME PATTERN WILL EVOLVE OVER THE SOUTHEASTERN UNITED STATES AS ATLANTIC HIGH PRESSURE EXPANDS OVER THE AREA THROUGH MIDWEEK. AS THIS OCCURS...DEEPEST MOISTURE WILL SHIFT INLAND AND WILL BE THE MAIN SOURCE OF PRECIP ACTIVITY EACH AFTERNOON WHILE WEAK H5 SHORTWAVES PASS OVERHEAD. DESPITE THE INLAND SHIFT OF DEEPEST MOISTURE...LIGHT ONSHORE FLOW WILL SUPPORT PWATS BETWEEN 1.5 TO 2 INCHES AS WELL AS SCATTERED SHOWERS AND/OR THUNDERSTORMS OVER SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA. HOWEVER...EXPECT MOST SHOWERS/THUNDERSTORMS TO GRADUALLY SHIFT INLAND BY EARLY AFTERNOON EACH DAY ALONG OR AHEAD A SEABREEZE. OVERALL HIGH TEMPS SHOULD RANGE IN THE UPPER 80S TO AROUND 90 EACH AFTERNOON. OVERNIGHT LOWS WILL RANGE IN THE LOW 70S INLAND TO MID/UPPER 70S ALONG THE COAST. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... A TYPICAL SUMMERTIME PATTERN WILL PERSIST THROUGH LATE WEEK AS ATLANTIC HIGH PRESSURE REMAINS OVER THE SOUTHEAST. CONDITIONS SHOULD REMAIN SOMEWHAT DRYER THROUGH FRIDAY WITH WEST/SOUTHWEST FLOW ALOFT. HIGH PRESSURE WILL THEN GRADUALLY RETREAT SOUTH AND EAST INTO THE WEEKEND AS A WEAK TROUGH OF LOW PRESSURE APPROACHES FROM THE NORTHWEST. A SLIGHT CHANCE OF SHOWERS AND/OR THUNDERSTORMS WILL BE POSSIBLE EACH DAY...WITH POSSIBLY INCREASING CHANCES ON SUNDAY BEFORE SFC HIGH PRESSURE AND DRYER MID LVL AIR SHIFTS OVER THE SOUTHEAST INTO EARLY NEXT WEEK. OVERALL HIGH TEMPS SHOULD RANGE IN THE UPPER 80S TO LOWER 90S EACH AFTERNOON...HIGHEST OVER INLAND AREAS IN SOUTHEAST GEORGIA. OVERNIGHT LOW TEMPS SHOULD RANGE IN THE LOW 70S INLAND TO LOW/MID 70S ALONG THE COAST. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... A MAINLY VFR FORECAST THIS TAF CYCLE AT THE KCHS/KSAV TERMINALS WITH POTENTIAL FOR BRIEF MVFR CIGS JUST AFTER SUNRISE AS THE LAND HEATS AND CUMULUS FIELDS DEVELOP. SCATTERED SHOWERS DEVELOPING THIS MORNING IN THE COASTAL CORRIDOR PER LATEST RADAR AND MODEL OUTPUT...PUSHING INLAND THIS AFTERNOON. IF DEEPER CONVECTION DEVELOPS IT COULD SLIDE BACK INTO THE THE TAF CORRIDOR AFTER MID AFTERNOON AS STEERING FAVORS A SW-NE TRAJECTORY. CONFIDENCE LOW ON TIMING OF ANY TSTMS AT THE TERMINALS TODAY. EXTENDED AVIATION OUTLOOK...VFR CONDITIONS ARE EXPECTED TO PREVAIL TUESDAY THROUGH SATURDAY AS HIGH PRESSURE PERSISTS OVER THE SOUTHEAST. BRIEF MVFR CIGS/VSBYS ARE POSSIBLE EACH AFTERNOON WITH INLAND MOVING SHOWERS AND/OR THUNDERSTORMS. && .MARINE... ATLC HIGH PRES WILL BE THE MAIN PLAYER FOR THE WATERS. MAINLY A LIGHT SE TO SSE FLOW THROUGH TONIGHT WITH SEAS 2 TO 3 FT. TUESDAY THROUGH FRIDAY...WINDS/SEAS ARE EXPECTED TO REMAIN WELL BELOW SMALL CRAFT ADVISORY LEVELS THROUGH LATE WEEK WITH HIGH PRESSURE DOMINATING THE WATERS. IN GENERAL...SOUTH TO SOUTHEAST WINDS WILL REMAIN AT OR BELOW 10-12 KT...HIGHEST NEAR SEABREEZE CIRCULATIONS ALONG THE COAST. SEAS WILL REMAIN AT OR BELOW 3 FT...HIGHEST IN OUTER GEORGIA WATERS. WATERSPOUTS...IT IS LOOKING DECENT THIS MORNING GIVEN INSTABILITY AND LIGHT CHAOTIC WIND FIELDS. WILL BE WAITING FOR SUNRISE TO SPOT CU LINES AND LAND BREEZE BOUNDARIES BEFORE ISSUING ANY MARINE WEATHER STATEMENTS. RIP CURRENTS...A SLIGHT INCREASE IN SWELLS COULD LEAD TO A MODERATE RISK OF RIPS BY MID WEEK. LOW RISK AT AREA BEACHES TODAY. && .TIDES/COASTAL FLOODING... GIVEN THE PERIGEAN SPRING TIDES...ADDITIONAL COASTAL FLOOD ADVISORIES ARE POSSIBLE THROUGH MID-WEEK WITH THE EVENING HIGH TIDE CYCLE. THIS EVENINGS HIGH TIDE SHORTLY BEFORE SUNSET COULD PRODUCE SHALLOW COASTAL FLOODING IN DOWNTOWN CHARLESTON AND FORT PULASKI ONCE AGAIN. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM... SHORT TERM...DPB LONG TERM...DPB AVIATION... MARINE...DPB TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
1109 AM EDT Mon Aug 19 2013 ...Forecast Update... Issued at 1107 AM EDT Mon Aug 19 2013 Fog continues to mix out across the southern forecast area this morning. In most locations, the fog has transitioned over to a low stratus deck which will take some time to mix out more fully. We expect that to occur around lunch time or early this afternoon. Cu field has become better defined across southern KY this morning despite having a bit more capping aloft. A few isolated showers will be possible mainly along and SE of the BG Parkway. Additional isolated showers/storms will be possible later this afternoon. Forcing is fairly weak from a dynamical standpoint, but differential heating is probably going to be main forcing mechanism this afternoon. Temperatures are currently in the lower 70s across the south, with a belt of mid-upper 70s along and just north of the Ohio River. Obviously the thicker cloud cover to the south will augment the solar insolation a bit this afternoon which will likely lead to a N-S temperature gradient. Highs in the 80-85 degree range in areas from the KY Parkways and northward still look good. Lower 80s down across the south and southeastern sections are still attainable, but will probably occur a little later in the afternoon due to the cloud cover delaying insolation. Update issued at 530 AM EDT Mon Aug 19 2013 Updated the forecast to remove areas of fog with patchy dense fog from southeast Indiana and the Bluegrass region of KY. Mid level clouds and lesser low level moisture than central and southern KY (where patches of dense fog have been reported) have limited fog formation over southeast Indiana and the Bluegrass. Downgraded this area to just patchy fog for the rest of the pre-dawn hours. Issued an SPS for portions of south and central KY where patchy dense fog has been reported and where it rained yesterday (which should be fog prone). Few-sct mid level clouds continue to move over this area improving fog at times so feel dense fog coverage will remain patchy. .SHORT TERM (Now through Tuesday)... Issued at 330 AM EDT Mon Aug 19 2013 The main forecast concern in the short term will be fog this morning. A very moist low level atmosphere along with very light or nearly calm winds have created an ideal environment for fog formation which we`ve already seen develop in our area. The worst fog spots remain over southern IL/western KY and over southwest Ohio. The 5Z RAP model has these fog areas handled well and expect them to expand into central KY and portions of southeast IN. Low clouds will also accompany the fog as soundings indicate a shallow layer of trapped moisture under a weak inversion. With these thoughts in mind, think that most locations over southern IN and central KY will see areas of fog this morning. Some locations over central KY and southeast IN will probably see patches of dense fog as well assuming the low clouds don`t inhibit fog density too much. Will highlight the patchy dense fog in the HWO this morning and monitor closely in case it becomes more widespread and an SPS or dense fog advisory is need. For the rest of the day, fog should burn off fairly quickly after sunrise. With an upper trough passing through the region, can`t rule out an isld shower over portions of south and east central KY. However, did scale the area of potential precip back a bit. High temperatures should reach the low to mid 80s this afternoon. Tonight a second upper trough will settle into the mid Mississippi River Valley. Some fog may be possible but not as widespread as this morning. Will continue inherited patchy fog mainly in river valleys. Lows tonight will be in the mid 60s. For Tues, expect a 20% chance of showers/t-storms to expand from south to north over the area throughout the day as a vort wave on the eastern side of the upper trough push north through our area. Any convection would be on the weak side. Tuesday afternoon high temps should be in the low to mid 80s with southern Indiana being the hottest due to a longer period of sunshine before clouds/isld convection move in. .LONG TERM (Tuesday Night through Sunday)... Issued at 311 AM EDT Mon Aug 19 2013 The models have finally come into agreement with a mid-level low that forms over the Ohio Valley at the start of this forecast period. This cutoff low hangs out in the region through Thursday night when it undergoes a transformation into an open wave in response to an approaching shortwave. This shortwave rides around the periphery of a stout ridge building in over the Plains and looks to exit the forecast area by early Saturday. The ridge continues to build in from the west, giving us dry conditions through the end of the weekend and into early next week. Tuesday night through Thursday: For this issuance, have introduced slight chance PoPs for Tuesday night as the low establishes itself overhead and surface southerly flow allows for moisture to be pulled in. Chance PoPs continues for Wednesday as daytime heating assists in convection across the area. With the loss of daytime heating and in conjunction with general model consensus, have kept PoPs out overnight Wednesday into early Thursday. As the low is depicted to begin traversing eastward Thursday, have only slight chance during the day with the primary focus for possible convection more toward eastern KY. The models have the low slowly but surely progressing eastward during this time frame and am a little skeptical on its speed. How quickly the low exits will depend on the timing of a weak frontal boundary attempting to lay out across the southern Great Lakes by Thursday night. Thursday night through Friday night: Have gone with slight chance PoPs strictly across the northern sections as the alluded to frontal boundary approaches from the north. The front stalls well to our north and does not currently appear to be a factor for us beyond Friday. The aforementioned shortwave swings around the region Friday, hence the slight to chance PoPs under diurnally-driven conditions. Again, skepticism sets in for the timing of it all as it seems to really move through a little too quickly. For now, have kept the area dry Friday night until a better handle on the progression of everything plays out. Temperatures will be more difficult to predict Tuesday night through Friday night as cloudy skies and/or rain will obviously wreck havoc. What can be said with confidence is that highs will continue to run slightly below normal and lows will flirt with normal. Saturday through Sunday: With that ridge building in, we`ll begin to see real signs of summer return as temperatures look to rebound back toward normal and partly to mostly sunny skies prevail. && .AVIATION (12Z TAF Update)... Issued at 635 AM EDT Mon Aug 19 2013 While VLIFR conditions exist at BWG, vsbys/cigs at SDF/LEX have not been near as bad as originally thought thanks to a persistent mid level cloud deck overnight. So for the rest of the day, expect VFR conditions at all TAF sites after fog burns off at BWG within the next few hours. Winds will be light out of the ENE throughout the TAF period. BWG will once again be fog prone tomorrow morning, but it should not be as dense as this morning`s fog. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Update.........MJ Short Term.....AMS Long Term......lg Aviation.......AMS
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
702 AM EDT Mon Aug 19 2013 ...Updated Aviation Discussion... ...Forecast Update... Issued at 530 AM EDT Mon Aug 19 2013 Updated the forecast to remove areas of fog with patchy dense fog from southeast Indiana and the Bluegrass region of KY. Mid level clouds and lesser low level moisture than central and southern KY (where patches of dense fog have been reported) have limited fog formation over southeast Indiana and the Bluegrass. Downgraded this area to just patchy fog for the rest of the pre-dawn hours. Issued an SPS for portions of south and central KY where patchy dense fog has been reported and where it rained yesterday (which should be fog prone). Few-sct mid level clouds continue to move over this area improving fog at times so feel dense fog coverage will remain patchy. .SHORT TERM (Now through Tuesday)... Issued at 330 AM EDT Mon Aug 19 2013 The main forecast concern in the short term will be fog this morning. A very moist low level atmosphere along with very light or nearly calm winds have created an ideal environment for fog formation which we`ve already seen develop in our area. The worst fog spots remain over southern IL/western KY and over southwest Ohio. The 5Z RAP model has these fog areas handled well and expect them to expand into central KY and portions of southeast IN. Low clouds will also accompany the fog as soundings indicate a shallow layer of trapped moisture under a weak inversion. With these thoughts in mind, think that most locations over southern IN and central KY will see areas of fog this morning. Some locations over central KY and southeast IN will probably see patches of dense fog as well assuming the low clouds don`t inhibit fog density too much. Will highlight the patchy dense fog in the HWO this morning and monitor closely in case it becomes more widespread and an SPS or dense fog advisory is need. For the rest of the day, fog should burn off fairly quickly after sunrise. With an upper trough passing through the region, can`t rule out an isld shower over portions of south and east central KY. However, did scale the area of potential precip back a bit. High temperatures should reach the low to mid 80s this afternoon. Tonight a second upper trough will settle into the mid Mississippi River Valley. Some fog may be possible but not as widespread as this morning. Will continue inherited patchy fog mainly in river valleys. Lows tonight will be in the mid 60s. For Tues, expect a 20% chance of showers/t-storms to expand from south to north over the area throughout the day as a vort wave on the eastern side of the upper trough push north through our area. Any convection would be on the weak side. Tuesday afternoon high temps should be in the low to mid 80s with southern Indiana being the hottest due to a longer period of sunshine before clouds/isld convection move in. .LONG TERM (Tuesday Night through Sunday)... Issued at 311 AM EDT Mon Aug 19 2013 The models have finally come into agreement with a mid-level low that forms over the Ohio Valley at the start of this forecast period. This cutoff low hangs out in the region through Thursday night when it undergoes a transformation into an open wave in response to an approaching shortwave. This shortwave rides around the periphery of a stout ridge building in over the Plains and looks to exit the forecast area by early Saturday. The ridge continues to build in from the west, giving us dry conditions through the end of the weekend and into early next week. Tuesday night through Thursday: For this issuance, have introduced slight chance PoPs for Tuesday night as the low establishes itself overhead and surface southerly flow allows for moisture to be pulled in. Chance PoPs continues for Wednesday as daytime heating assists in convection across the area. With the loss of daytime heating and in conjunction with general model consensus, have kept PoPs out overnight Wednesday into early Thursday. As the low is depicted to begin traversing eastward Thursday, have only slight chance during the day with the primary focus for possible convection more toward eastern KY. The models have the low slowly but surely progressing eastward during this time frame and am a little skeptical on its speed. How quickly the low exits will depend on the timing of a weak frontal boundary attempting to lay out across the southern Great Lakes by Thursday night. Thursday night through Friday night: Have gone with slight chance PoPs strictly across the northern sections as the alluded to frontal boundary approaches from the north. The front stalls well to our north and does not currently appear to be a factor for us beyond Friday. The aforementioned shortwave swings around the region Friday, hence the slight to chance PoPs under diurnally-driven conditions. Again, skepticism sets in for the timing of it all as it seems to really move through a little too quickly. For now, have kept the area dry Friday night until a better handle on the progression of everything plays out. Temperatures will be more difficult to predict Tuesday night through Friday night as cloudy skies and/or rain will obviously wreck havoc. What can be said with confidence is that highs will continue to run slightly below normal and lows will flirt with normal. Saturday through Sunday: With that ridge building in, we`ll begin to see real signs of summer return as temperatures look to rebound back toward normal and partly to mostly sunny skies prevail. && .AVIATION (12Z TAF Update)... Issued at 635 AM EDT Mon Aug 19 2013 While VLIFR conditions exist at BWG, vsbys/cigs at SDF/LEX have not been near as bad as originally thought thanks to a persistent mid level cloud deck overnight. So for the rest of the day, expect VFR conditions at all TAF sites after fog burns off at BWG within the next few hours. Winds will be light out of the ENE throughout the TAF period. BWG will once again be fog prone tomorrow morning, but it should not be as dense as this morning`s fog. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Update.........AMS Short Term.....AMS Long Term......lg Aviation.......AMS
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
701 AM EDT MON AUG 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 359 AM EDT MON AUG 19 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A ZONAL FLOW OVER SRN CANADA TO THE N OF UPR RDG EXTENDING FM THE WRN PLAINS INTO THE GREAT LKS. THE WX OVER UPR MI IS QUIET EARLY THIS MRNG...WITH DRY/STABLE AIRMASS DEPICTED ON THE 00Z MPX/GRB RAOBS DOMINATING THE AREA. THERE ARE 2 SHRTWVS EMBEDDED IN THE ZONAL FLOW THAT ARE OF CONCERN. THE FIRST OF THESE IS MOVING EWD THRU THE DAKOTAS AND ARPCHG NW MN...ACCOMPANIED BY SCT SHRA/TS. THE SECOND IS MOVING THRU NW ONTARIO WITH A CLUSTER OF SHRA/TS NW OF LK NIPIGON...BUT SOME ISOLD SHRA/TS WITHIN THE COMMA TAIL OF THIS FEATURE EXTEND FARTHER S INTO THE MN ARROWHEAD UNDER SOME H85-5 QVECTOR CNVGC ASSOCIATED WITH FAIRLY VIGOROUS H85 THETA E ADVECTION IN ADVANCE OF AXIS OF HIER H85 DEWPTS UP TO 15C AT ABERDEEN SDAKOTA AND 13C AT INL. WHILE THE 00Z MPX/GRB RAOBS ARE QUIET DRY/STABLE WITH KINX OF 0/-2 RESPECTIVELY AND PWAT ARND 0.75 INCH /NEAR 75 PCT OF NORMAL/...THE 00Z INL RAOB IS MORE MOIST AND CONDITIONALLY UNSTABLE...WITH KINX OF 36 AND PWAT 1.47 INCH /175 PCT OF NORMAL/. DESPITE THE RATHER IMPRESSIVE MOISTENING...LATEST TRENDS INDICATE FEW IF ANY LTG STRIKES WITHIN THE CONVECTION. MAIN FCST CONCERNS IN THE SHORT TERM ARE RELATED TO PCPN CHCS ASSOCIATED WITH PAIR OF SHRTWVS NOTED ABOVE. TDAY...SHRTWVS MOVING INTO MN AND THRU ONTARIO ARE PROGGED TO CONTINUE DRIFTING E THRU THE DAY. AS AXIS OF VIGOROUS H85 THETA E ADVECTION/H85-5 QVECTOR CNVGC SHIFT E THIS MRNG...EXPECT SOME ISOLD SHRA TO INVADE THE WRN COUNTIES. BUT MODEL GUIDANCE IN GENERAL SHOWS THE SHARPER H85-5 QVECTOR CNVGC ASSOCIATED WITH THE ONTARIO SHRTWV PASSING TO THE N AND MORE VIGOROUS FORCING IN ADVANCE OF THE MN DISTURBANCE FOCUSING TO THE S BEFORE FADING IN THE AFTN. SO GOING FCST SHOWING A DIMINISHING TREND IN THE POPS THRU THE MRNG SEEMS ON TRACK. GIVEN OBSVD LTG STRIKES AND TENDENCY FOR DIMINISHING DYNAMIC SUPPORT...REMOVED MENTION OF TS THIS MRNG. WHETHER DAYTIME HEATING /DESTABILIZATION CAN REINVIGORATE/SUSTAIN ANY CONVECTION WL BE THE CONCERN FOR THE AFTN. IN FACT...THE 00Z REGIONAL GEM AND GFS ARE THE ONLY MODELS THAT GENERATE ANY PCPN OVER THE CWA THIS AFTN. THE GFS FCST SDNGS SHOW RATHER UNIMPRESSIVE LAPSE RATES WITH A TENDENCY FOR A PERSISTENT CAP AND WARMING MID LVL TEMPS IN THE 18Z-24Z TIME FRAME ASSOCIATED WITH THE FADING DYNAMIC SUPPORT. NAM/GFS MOS POPS ARE UNDER 10 AT MOST PLACES...BUT OPTED TO RETAIN SCHC POPS TO INCLUDE TS WITH ARRIVAL OF MOISTER AIR/PWAT UP TO 1.5 INCH AND SFC TEMPS EXPECTED TO REACH ARND 85 THAT WL LIFT MUCAPE UP TO 800-1000J/KG AWAY FM THE MODERATING INFLUENCE OF THE LKS. TNGT...WITH RISING HGTS/DNVA/DEEP QVECTOR DVGC...TNGT WL BE DRY AS ANY AFTN CONVECTION FIZZLES BEFORE SUNSET UNDER THE MID LVL WARMING/LOWERING SUN ANGLE. ALTHOUGH SKIES WL TURN MOCLR...STEADY SW WIND SHOULD ACT TO LIMIT THE DIURNAL TEMP FALL. THE WARMEST MIN TEMPS ARE MOST LIKELY NEAR LK SUP OVER THE W HALF...WHERE THE PRES GRADIENT WL BE A BIT TIGHER/H925 WINDS 20-25 KTS AND THIS FLOW WL DOWNSLOPE. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 359 AM EDT MON AUG 19 2013 STARTING TUE...THE CWA WILL BE BETWEEN A SFC HIGH OVER THE ATLANTIC/ERN CONUS AND AND SFC TROUGH FROM HUDSON BAY INTO THE NRN PLAINS STATES. SOME OF THE MODELS ARE HINTING AT SOME PRECIP TUE AFTERNOON...BUT ANY PRECIP SHOULD BE ISOLATED AT BEST GIVEN THAT THERE WILL NOT BE MUCH MOISTURE AVAILABLE. BEST CHANCE FOR ISOLATED SHOWERS AND THUNDERSTORMS WILL BE OVER NCENTRAL UPPER MI WHERE LAKE BREEZE CONVERGENCE WILL HELP ENCOURAGE CONVECTION ALONG. 850MB TEMPS AT 18Z TUE WILL BE RIGHT AROUND 17-18C AND WITH MOSTLY SUNNY SKIES SHOULD BE ABLE TO GET HIGH TEMPS IN THE 80S TO AROUND 90. MODELS ARE IN BETTER AGREEMENT FOR THAT TROUGH/COLD FRONT TO THE NW TO DROP ACROSS THE CWA ON WED/WED NIGHT...BUT THERE REMAINS SOME SUBTLE YET IMPORTANT UNCERTAINTY FOR THE SYSTEM. MAIN QUESTION IS WITH THE EXACT TIMING OF THE COLD FRONT...WHICH EVEN THOUGH MODELS AGREE WELL ON...THINK THAT IT WILL NOT BE CERTAIN UNTIL A LATER TIME. THE TIMING OF FROPA IS IMPORTANT BECAUSE WITH 850MB TEMPS UP TO 20C...TEMPS MAY BE COLDER THAN WHAT IS IN THE FORECAST /MAINLY OVER THE W WHERE THE FRONT MAY COME IN EARLIER THAN PREVIOUSLY INDICATED BY MODELS/. THINK THAT AREAS THAT HAVE NOT BEEN IMPACTED BY THE FRONT /AND ASSOCIATED PRECIP AND CLOUD COVER/ BY AROUND PEAK HEATING TIME WILL GET INTO THE LOW 90S /AWAY FROM LAKE MICHIGAN/. SO...IF THE COLD FRONT COMES IN AS THE MODELS ARE CURRENTLY INDICATING /INTO WRN UPPER MI BY 18Z WED AND CENTRAL UPPER MI BY 00Z THU/...PORTIONS OF WRN UPPER MI WOULD SEE HIGH TEMPS POSSIBLY 10 DEGREES COLDER THAN WHAT THE PREVIOUS FORECAST HAD. ON THE FLIP SIDE...THE FRONT COULD VERY WELL COME IN LATER THAN INDICATED BY MODELS...MEANING THE PREVIOUS FORECAST MAY BE RIGHT ON. AT THIS POINT WITH THE UNCERTAINTY...WILL NOT CHANGE TEMPS MUCH FOR WED. THE OTHER IMPACT WITH FROPA TIMING IS ON CONVECTION...SIGNIFICANT SBCAPE VALUES OF 1500-2500J/KG SHOULD BE PRESENT IN AIRMASS AHEAD OF COLD FRONT AROUND PEAK HEATING...SO WHEN THE FRONT MOVES THROUGH WILL DETERMINE STRENGTH/COVERAGE OF CONVECTION. AT THIS POINT...NOT TOO EXCITED WITH AREAL EXTENT OF CONVECTION GIVEN THAT MOISTURE WILL BE SOMEWHAT LIMITED /AT LEAST EARLY ON/. AT THE SAME TIME...THAT DRY AIR WILL HELP DCAPE VALUES GET UP TO AROUND 1000J/KG AND WITH HIGH FREEZING LEVEL AROUND 14KFT...MAIN THREAT FROM ANY STRONGER OR ISOLATED SEVERE STORMS WOULD BE STRONG WINDS. THURSDAY CERTAINLY LOOKS COOLER AND DRIER AS 850MB TEMPS AT 18Z THU WILL BE AROUND 13C WITH SFC HIGH PRESSURE MOVING IN FROM THE W. HIGH TEMPS LOOK TO BE IN THE 70S TO AROUND 80 OVER THE SCENTRAL CWA. AMPLIFIED UPPER LEVEL RIDGE WILL BE WELL TO THE W OF THE CWA. MODELS IN MUCH BETTER AGREEMENT FOR FRI WITH HAVING THE SFC HIGH EXIT TO THE E ON FRI AS THE UPPER RIDGE AXIS MOVES OVERHEAD LATE IN THE DAY. WITH SLY FLOW NOT KICKING IN AND UPPER RIDGE NOT ARRIVING UNTIL LATE IN THE DAY OR UNTIL FRI NIGHT...WILL NOT HAVE SUFFICIENT ADVECTION OF WARMER AIRMASS INTO THE AREA. HIGH TEMPS LOOK SIMILAR OR A DEGREE OR TWO COOLER THAN THURSDAY...WITH HIGHS PRIMARILY IN THE 70S /WITH SOME COOLER SPOTS NEAR LAKE SUPERIOR/. UNCERTAINTY INCREASES CONSIDERABLY FOR SAT AND SUN DUE TO MODEL DISAGREEMENT AND RUN TO RUN DISCONTINUITY. WILL JUST USE CONSENSUS OF MODELS FOR THIS PERIOD. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 701 AM EDT MON AUG 19 2013 A LO PRES TROF CROSSING THE AREA WL BRING SOME ISOLD -SHRA AND PERHAPS A TS TO THE TAF SITES W-E TODAY. EVEN IF THERE IS A SHRA AT ONE OF THE AIRPORTS...CONDITIONS ARE LIKELY TO REMAIN VFR GIVEN THE RELATIVELY DRY NATURE OF THE AIRMASS. OTRW...EXPECT A GUSTY SW WIND UNDER THE SHARPER PRES GRADIENT IN ADVANCE OF THE APRCHG TROF AND WITH DAYTIME HEATING/MIXING. LARGE SCALE SUBSIDENCE BEHIND THE TROF AND LOSS OF DAYTIME HEATING WL ALLOW FOR DRY/VFR CONDITIONS TNGT. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 359 AM EDT MON AUG 19 2013 OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE GREAT LAKES REGION. THE ARRIVAL OF MORE HUMID AIR FOR TUE/WED MAY RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL BE MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE. ANY FOG WILL DISSIPATE THU FOLLOWING A COLD FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...TITUS AVIATION...KC MARINE...KC
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
647 AM EDT MON AUG 19 2013 .SYNOPSIS... A WARM FRONT WILL GRADUALLY BRING MORE SEASONABLE TEMPERATURES OVER THE NEXT FEW DAYS. WEAK UPPER LEVEL DISTURBANCES WILL KEEP THUNDERSTORMS SCATTERED THROUGH THE MIDDLE OF THE WEEK. THE LATE WEEK PERIOD WILL TURN EVEN WARMER WITH LOWER RAIN CHANCES. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM...BASED ON CURRENT RADAR TRENDS...INCREASED RAIN CHANCES TO CATEGORICAL VALUES NW THIS MORNING AND TO LIKELY VALUES OVER MUCH OF THE REST OF THE AREA LATER TODAY EXPECTING A LITTLE MORE COVERAGE THAN PREVIOUSLY THOUGHT. SYNOPSIS...TEMPERATURES AND SKY INFORMATION IN THE PREVIOUS DISCUSSION FROM 3 AM IS STILL VALID. THE 3 AM DISCUSSION FOLLOWS: AS OF 3 AM MONDAY...MODEL GUIDANCE EJECTS THE UPPER LOW OVER THE MISSISSIPPI VALLEY TO THE NORTHEAST TODAY AND TONIGHT. THE MOTION OF THIS FEATURE WILL ALLOW LIFT ASSOCIATED WITH THE ENTRANCE REGION OF THE UPPER JET TO AFFECT THE AREA TODAY...PARTICULARLY NW SECTIONS. IN ADDITION MODEL GUIDANCE SHOWS WEAK ISENTROPIC LIFT OVER THE AREA TODAY AND THE OLD FRONTAL BOUNDARY REMAINS IN THE AREA AS WELL. FORECAST WILL HAVE HIGH CHANCE TO LIKELY POPS TODAY WITH HIGHEST NUMBERS NW...TAPERING BACK TO SLIGHT CHANCE TONIGHT. AFTERNOON MAXIMUM TEMPERATURES UNDER A PARTLY TO MOSTLY CLOUDY SKY SHOULD BE LIMITED TO THE MIDDLE 80S. MINS TONIGHT SHOULD FALL TO THE LOWER 70S...PERHAPS UPPER 60S NW. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 AM MONDAY...MODELS HAVE SLOWED IN SHOWING THE INLAND PROGRESSION OF THE MID LEVEL WEST ATLANTIC RIDGE. NOW TUESDAY IS DEPICTED AS ONE LAST DAY WHERE MOISTURE REMAINS DEEP AND A FEW WEAK SHORTWAVES EMBEDDED IN THE 10KT 500MB FLOW PROVIDE SOME SYNOPTIC SCALE ASCENT. TEMPERATURES WILL BE CLOSE CLIMO BUT SLIGHTLY HIGHER THAN NORMAL POPS APPEAR TO BE WARRANTED. WEDNESDAY THE WEST ATLANTIC RIDGE GAINS IN AMPLITUDE BACKING LOCAL FLOW ALMOST TO SOUTHERLY. MEANWHILE THE CHANNEL OF DEEPEST MOISTURE GETS SHUNTED JUST TO OUR WEST. ISO TO WIDELY SCATTERED CONVECTION TILL POSSIBLE ALONG MESOSCALE BOUNDARIES AND TEMPS MAY RISE A FEW DEG ABOVE TUESDAY COUNTERPARTS. && .LONG TERM /THURSDAY THROUGH SUNDAY/... AS OF 3 AM MONDAY...FOR THE FIRST FEW DAYS OF THE LONG TERM THE WEST ATLANTIC UPPER RIDGE BUILDS IN FAVOR OF THE BUILDING RIDGE OVER THE WESTERN U.S. A WEAK SHEAR AXIS CROSSES THE REGION THURSDAY NIGHT INTO FRIDAY. WEAK ASCENT ASSOCIATED WITH THIS FEATURES SHOULD BRING SOME HIGHER RAIN CHANCES THAN WEDNESDAY BUT STILL PROBABLY NOT MUCH HIGHER THAN CLIMO. THE REMAINDER OF THE PERIOD KEEPS A STRONG UPPER RIDGE ACROSS THE MIDDLE OF THE NATION WITH TROUGHINESS ALONG BOTH COASTLINES. BARRING THE RELATIVELY NEW IDEA OF THE GFS OF A BACKDOOR COLD FRONT OVER THE WEEKEND THIS WILL MEAN SLIGHTLY ABOVE CLIMO TEMPS AND SLIGHTLY LOWER THAN NORMAL THUNDERSTORM COVERAGE. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... AS OF 06Z...SURFACE DEWPOINTS IN THE LOW TO MID 70S WITH CALM/LIGHT WINDS SUGGEST THE LOW-LEVEL CONDITIONS ARE PRIMED FOR FOG/STRATUS OVERNIGHT. MVFR CIGS/VSBYS ARE EXPECTED AT THE COASTAL TERMS...WITH PERHAPS SOME BRIEF IFR VSBYS AT FOG-PRONE KCRE. KFLO/KLBT HAVE THE BEST CHANCES FOR IFR...AS THE LATEST GUIDANCE FAVORS STRATUS DEVELOPING AROUND DAYBREAK AT THE INLAND SITES. THE LATEST HRRR RUNS SHOW SOME SHOWERS MOVING ONSHORE IN THE EARLY MORNING HOURS...SO HAVE MENTIONED PCPN FOR THE COASTAL SITES AS WELL. CURRENT SHOWER ACTIVITY INLAND HAS A CHANCE TO AFFECT THE INLAND TERMINALS THROUGH ABOUT 09Z...PARTICULARLY FLO. MORE WIDELY SCATTERED SHOWERS ARE EXPECTED WITH DAYTIME HEATING AS A COASTAL TROUGH WILL BE POSITIONED OVER THE CAROLINAS. CIGS MAY BOUNCE AROUND BETWEEN VFR AND MVFR DURING THE DAY...WITH MVFR MORE LIKELY DURING PERIODS OF SHRA. SLIGHTLY HIGHER POPS INLAND ARE REFLECTED IN THE TAFS. CALM TO LIGHT WINDS WILL BECOME S-SE AOB 10 KTS AT KMYR...KCRE AND KILM IN THE AFTN HOURS. EXTENDED OUTLOOK...EARLY MORNING FOG/STRATUS POSSIBLE TUESDAY AND WEDNESDAY. ISOLATED TO SCATTERED AFTN SHOWERS/T-STORMS EXPECTED THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 3 AM MONDAY...OUTSIDE OF LIGHT N TO NW WINDS EARLY TODAY DUE TO A LAND BREEZE...EXPECT SE TO S FLOW AT 10 KT OR LESS THROUGH THE PERIOD. SEAS ARE EXPECTED TO RUN 2 TO 3 FT. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 AM MONDAY...TWIN CENTERED HIGH PRESSURE ON TUESDAY...ONE OFF THE COAST AND THE OTHER OVER THE MOUNTAINS. RESULTING FLOW ACROSS THE WATERS WILL BE QUITE LIGHT AND SOMEWHAT VARIABLE ALTHOUGH A PREDOMINANTLY SOUTHERLY COMPONENT WILL BE PRESENT. THE OVER LAND HIGH WILL BE SHRINKING ON WEDNESDAY WITH LITTLE EFFECT ON LOCAL WINDS AND THE CONTINUED DIMINUTIVE SEAS. LONG TERM /THURSDAY THROUGH FRIDAY/... AS OF 3 AM MONDAY...HIGH PRESSURE OVER THE LANDMASS/EASTERN U.S. DURING THE SHORT TERM FINALLY WASHES OUT ENOUGH TO BRING A MORE SEASONABLE SW FLOW ON THURSDAY AROUND THE WEST ATLANTIC HIGH. THIS FLOW CONTINUES INTO FRIDAY BUT MAY BE EQUALLY BORNE OF PIEDMONT TROUGHINESS AS THE WEAKENING WEST ATLANTIC RIDGE. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...NONE. && $$ SYNOPSIS...MBB NEAR TERM...RAN SHORT TERM...MBB LONG TERM...MBB AVIATION...BJR/31
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
641 AM CDT MON AUG 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 327 AM CDT MON AUG 19 2013 THE MAIN FOCUS FOR TODAY IS ON A MID LEVEL TROUGH THAT WILL COME THROUGH AND WHETHER IT WILL HAVE ENOUGH LIFT TO OVERCOME THE DRY LOW LEVEL AIR AND PRODUCE SOME RAIN SHOWERS. THIS MID LEVEL TROUGH IS CURRENTLY ANALYZED VIA WATER VAPOR IR AND 19.06Z RAP 500MB ANALYSIS FROM SOUTHWESTERN ONTARIO THROUGH MINNESOTA AND EASTERN NEBRASKA. SOME VERY HIGH BASED RADAR RETURNS HAVE BEEN SHOWING UP ACROSS EASTERN SOUTH DAKOTA AND WESTERN MINNESOTA THOUGH THERE HAVE NOT BEEN MANY SIGHTS REPORTING THAT THE RAIN IS REACHING THE GROUND. THIS IS ALSO IN A BELT OF HIGHER LOW LEVEL MOISTURE TRANSPORT THAT IS TRAPPED UNDER A 700MB INVERSION...BUT IS HELPING TO RAISE SURFACE DEW POINTS. THIS IN TURN HAS CREATED A MORE UNSTABLE AIR MASS FROM THE DAKOTAS UP INTO NORTHERN MINNESOTA. THE 19.07Z RAP KEEPS MUCH OF THIS MOISTURE TRANSPORT AND HIGHER INSTABILITY OUT TO THE WEST TODAY...SO THIS TROUGH WILL BE ENTERING AN ENVIRONMENT THAT IS LESS FAVORABLE TO SEE THE SHOWERS CONTINUE. CONSIDERED PUTTING IN A MENTION OF SPRINKLES TODAY IN FOR SOUTHEAST MINNESOTA AND WESTERN TO NORTH CENTRAL WISCONSIN...BUT HELD OFF FOR THE TIME BEING SINCE REFLECTIVITIES OUT WEST APPEAR TO BE ON A WEAKENING TREND. MID TO HIGH LEVEL CLOUD COVER WILL BE FAIRLY WIDESPREAD FOR A PORTION OF THE DAY WHICH WILL KEEP TEMPERATURES DOWN A LITTLE BIT. THE 19.00Z NAM/GFS SHOW SOME WARMER 850/925MB AIR MOVING IN THIS AFTERNOON AS SOME OF THIS CLOUD COVER EXITS. EXPECT THAT WE WILL WARM UP PRETTY QUICKLY AS THIS OCCURS...BUT PERHAPS NOT AS HIGH AS PREVIOUSLY ADVERTISED. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 327 AM CDT MON AUG 19 2013 CONDITIONS WILL CONTINUE TO WARM INTO MID WEEK AHEAD OF A COLD FRONT/TROUGH THAT WILL PROPAGATE INTO THE REGION ON WEDNESDAY. WEDNESDAY IS EXPECTED TO BE THE WARMEST DAY OF THE WEEK WITH LOW LEVEL WARM AIR ADVECTION BUMPING 925MB TEMPERATURES UP TO AROUND 26C AND 850MB TEMPERATURES TO 20C. THIS WARM LAYER SHOULD ALSO HELP TO KEEP THE WARM SECTOR CAPPED OFF UNTIL THE COLD FRONT DROPS DOWN LATE WEDNESDAY AFTERNOON AND EVENING. THE AIR MASS WILL BECOME UNSTABLE WITH MODIFIED 19.00Z NAM/GFS SOUNDINGS...MODIFIED FOR LOWER DEW POINTS IN THE MID/UPPER 60S...SHOWING BETWEEN 1500-2500 J/KG OF 0-3KM MUCAPE ALONG A NARROW CORRIDOR JUST AHEAD OF THE FRONT. WIND SHEAR LOOKS MARGINAL WITH THE BETTER DEEP SHEAR IN CENTRAL MINNESOTA/NORTHERN WISCONSIN WHERE 500MB WINDS WILL BE AROUND 40KTS DUE TO THE MID LEVEL SHORT WAVE TROUGH DROPPING INTO THE NORTHERN GREAT LAKES. FURTHER SOUTHWEST ALONG THE FRONT CLOSER TO SOUTHERN MINNESOTA AND NORTHERN IOWA...19.00Z NAM/GFS SOUNDINGS/HODOGRAPHS DO SHOW SOME DIRECTIONAL/SPEED SHEAR IN THE LOWEST 2KM WHICH WOULD BE MORE FAVORABLE FOR STRONGER WINDS. BASED ON THE INSTABILITY AND SHEAR...IT APPEARS THAT LARGE HAIL AND DAMAGING WINDS STILL APPEAR TO BE THE MAIN THREATS IN THE LATE AFTERNOON INTO THE EVENING...PARTICULARLY ACROSS SOUTHEAST MINNESOTA...WESTERN WISCONSIN AND NORTHEAST IOWA. THE ISSUE THEN CONTINUES TO BE WITH HOW FAR SOUTH WILL THE COLD FRONT MAKE IT AND THEN HOW FAST DOES IT GET PUSHED BACK TO THE NORTH AS A WARM FRONT BY THE END OF THE WEEK. THE ECMWF HAS TRENDED TOWARD WHAT THE GFS/GEM HAVE BEEN ADVERTISING THE PAST FEW DAYS WITH HAVING THE FRONT DROP SOUTH INTO IOWA/NORTHERN ILLINOIS BY THURSDAY MORNING...BUT THE 19.00Z ECMWF STILL REMAINS THE FURTHEST NORTH WITH WHERE IT STALLS OUT. THERE ALSO IS BETTER CONTINUITY WITH THE NEXT TROUGH TRACKING ACROSS THE NORTHERN PLAINS ON FRIDAY INTO SATURDAY WHICH IS WHEN THE FRONT COMES BACK NORTH AS A WARM FRONT. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING) ISSUED AT 641 AM CDT MON AUG 19 2013 MVFR CONDITIONS ARE EXPECTED AT KLSE THROUGH 14Z THIS MORNING. OTHERWISE...VFR CONDITIONS ARE EXPECTED AT THE TAF SITES THROUGH THE FORECAST PERIOD. PATCHY FOG HAS DEVELOPED ALONG THE MISSISSIPPI RIVER THIS MORNING. PLAN ON VISIBILITIES BEING REDUCED TO AROUND 4SM AT KLSE BEFORE THE FOG FINALLY DISSIPATES AROUND 14Z. A WEAK UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE UPPER MISSISSIPPI RIVER VALLEY TODAY BRINGING SCATTERED TO BROKEN VFR CEILINGS. ALSO...SOUTHWEST WINDS WILL INCREASES TO AROUND 10KTS WITH GUSTS AROUND 20 KTS POSSIBLE THIS AFTERNOON. THE WINDS WILL SUBSIDE INTO THE 5 TO 7 KT RANGE TONIGHT. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM...HALBACH AVIATION...WETENKAMP
AREA FORECAST DISCUSSION
NWS SAN JOAQUIN VALLEY - HANFORD CA
309 PM PDT MON AUG 19 2013 .SYNOPSIS... A LOW PRESSURE CENTER OFF THE CENTRAL COAST WILL BRING A CHANCE OF MAINLY AFTERNOON AND EVENING THUNDERSTORMS OVER THE SIERRA NEVADA THROUGH WEDNESDAY. THERE WILL ALSO BE A SLIGHT CHANCE OF THUNDERSHOWERS FOR THE SAN JOAQUIN VALLEY THROUGH TUESDAY MORNING. THE LOW WILL LIFT NORTHEAST OUT OF THE REGION BY THURSDAY AND BRING A RETURN OF DRIER WEATHER FOR THE END OF THE WEEK. && .DISCUSSION... UPPER LOW OFF THE COAST IN CONJUNCTION WITH LARGE SCALE UPPER RIDGE OVER THE FOUR CORNERS IS PROVIDING A SQUEEZE PLAY TO STREAM MID LEVEL SUB TROPICAL MOISTURE INTO THE CENTRAL CA INTERIOR. T-STORMS ARE ONCE AGAIN FIRING UP OVER THE SIERRA AND ALONG THE TEHACHAPI RANGE ATTM. UPSLOPE CONDITIONS IN ASSOCIATION WITH MODERATE MUCAPES FROM THE VEGAS SOUNDING OF OVER 2000 J/KG ARE PROVIDING ENOUGH LIFT TO GET IT GOING AGAIN TODAY. BLENDED PWAT VALUES OF 1.0-1.5 ARE OVER THE REGION WILL PROVIDE ENOUGH MOISTURE TO SUPPORT THUNDERSTORMS. ACTIVE PATTERN WILL CONTINUE INTO THE OVERNIGHT HOURS AS UPPER LOW REMAINS STATIONARY OFF THE COAST AND MOISTURE FEED CONTINUES. 19Z RUN OF THE HRRR IS PAINTING MOST OF THE CWA WITH QPF FOR THIS EVENING. EVEN SPREADS QPF INTO THE VALLEY AND OVER TO THE WEST SIDE OF THE SJV. SOME FLASH FLOODING IS POSSIBLE WITH THE STORMS IN THE MOUNTAINS AS MOVEMENT IS ONLY AROUND 10 MPH. ADDITIONAL FIRE STARTS ARE ALSO POSSIBLE WITH NUMEROUS LIGHTNING STROKES ASSOCIATED THE STORMS. THE UPPER LOW BEGINS TO OPEN UP AND LIFT NE. BOTH THE MEAN ENSEMBLE GFS AND THE 12Z OPERATIONAL ECM ARE IN DECENT AGREEMENT WITH LIFTING THE FEATURE NE BY WED AND SW FLOW ALOFT SETTING UP WITH DRIER CONDITIONS. EPAC TROUGH WILL DIG SOUTH AND FEED ANOTHER ROUND OF SUB TROPICAL MOISTURE INTO THE REGION. HAVE INTRODUCED POPS FOR SUNDAY AND MONDAY OVER THE SIERRA AND OVER THE TEHACHAPIS. && .AVIATION... SCATTERED SHOWERS AND THUNDERSTORMS WITH LOCAL MVFR/IFR CONDITIONS EXPECTED TODAY...MAINLY OVER THE MOUNTAINS AND DESERT. OTHERWISE... VFR CONDITIONS WILL PREVAIL THROUGHOUT THE CENTRAL CALIFORNIA INTERIOR DURING THE NEXT 24 HOURS. && .AIR QUALITY ISSUES... ON MONDAY AUGUST 19 2013... UNHEALTHY FOR SENSITIVE GROUPS IN SEQUOIA NATIONAL PARK AND FOREST. FURTHER INFORMATION IS AVAILABLE AT VALLEYAIR.ORG && .CERTAINTY... THE LEVEL OF CERTAINTY FOR DAYS 1 AND 2 IS MEDIUM. THE LEVEL OF CERTAINTY FOR DAYS 3 THROUGH 7 IS HIGH. THIS INFORMATION IS PROVIDED AS PART OF A TRIAL PROJECT CONDUCTED BY THE NATIONAL WEATHER SERVICE SAN JOAQUIN VALLEY - HANFORD. CERTAINTY LEVELS INCLUDE LOW...MEDIUM...AND HIGH. PLEASE VISIT WWW.WEATHER.GOV/HNX/CERTAINTY.PHP /ALL LOWER CASE/ FOR ADDITIONAL INFORMATION AND/OR TO PROVIDE FEEDBACK. && .CLIMATE... RECORDS SITE DATE HI_MAX:YEAR LO_MAX:YEAR HI_MIN:YEAR LO_MIN:YEAR KFAT 08-19 108:1892 67:1976 74:2012 54:1916 KFAT 08-20 108:1919 76:1959 75:1986 54:1974 KFAT 08-21 108:1919 80:1968 76:1913 51:1959 KBFL 08-19 109:1950 78:1959 79:1961 52:1913 KBFL 08-20 112:1950 77:1959 79:1950 52:1912 KBFL 08-21 110:1919 80:1968 77:1982 51:1918 && .HNX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ PUBLIC...JDB AVN/FW...MV SYNOPSIS...ANDERSEN WEATHER.GOV/HANFORD
AREA FORECAST DISCUSSION
NWS SACRAMENTO CA
1030 AM PDT MON AUG 19 2013 .SYNOPSIS... CHANCE OF THUNDERSTORMS INTO THURSDAY AS A LOW PRESSURE SYSTEM ALONG THE CENTRAL COAST GRADUALLY MOVES THROUGH NORTHERN CALIFORNIA. HOT WEATHER WILL CONTINUE TODAY FOLLOWED BY A RETURN TO NEAR SEASONAL TEMPERATURES BY MID-WEEK. && .DISCUSSION... UPPER LEVEL LOW PRESSURE OFF THE COAST HAS DROPPED FURTHER TO SOUTH AND WEST. THIS SYSTEM IS PUMPING SIGNIFICANT MOISTURE INTO THE AREA. THE OAKLAND MORNING SOUNDING SHOWS THIS WITH PRECIPITABLE WATER AT OAKLAND AROUND 200 PERCENT OF NORMAL. SATELLITE SHOWS CLOUDS WRAPPING AROUND AND STREAMING WESTWARD THROUGH THE VALLEY, CURRENTLY EXTENDING NORTH AND SOUTH BETWEEN RED BLUFF AND GALT. THIS IS BRINGING OVERCAST SKIES TO THAT AREA. RADAR ALSO SHOWS SOME EMBEDDED RETURNS WITH PERHAPS SOME SPRINKLES IN THE VALLEY OR A FEW LIGHT RAIN SHOWERS THE MOUNTAINS AND FOOTHILLS. MESOSCALE MODELS SHOW MORE SIGNIFICANT PRECIPITATION SPREADING INTO THE MOUNTAINS BY THIS AFTERNOON. THE WRF EXTENDS SOME SHOWERS AND THUNDERSTORMS INTO THE NORTHERN AND PORTIONS OF THE CENTRAL SACRAMENTO VALLEY BY LATE AFTERNOON AND AM FORECASTING SCATTERED STORMS FOR THAT AREA. THE HRRR KEEPS MOST OF THE CONVECTION OVER HIGHER TERRAIN...THOUGH. THIS MAY BE DUE TO RELATIVELY DRY AIR NEAR THE SURFACE, WHICH IS EVIDENT IN AIRCRAFT SOUNDINGS THIS MORNING. THE SOUTHERN VALLEY LOOKS LIKE IT HAS LESS CHANCE OF ACTIVITY ALTHOUGH WILL KEEP SOME ISOLATED SHOWERS AND THUNDERSTORMS THERE FOR THIS EVENING. OVERALL, THE STRONGEST THUNDERSTORM ACTIVITY IS EXPECTED TO BE OVER THE SIERRA AND MOUNTAINS OF WESTERN PLUMAS COUNTY AND DOWN INTO THE FOOTHILLS WITH LOCALLY HEAVY RAIN AND SIGNIFICANT AMOUNTS OF CLOUD TO GROUND LIGHTNING POSSIBLE. RED FLAG WARNING CONTINUES FOR THE THREAT OF WILDFIRE STARTS DUE TO LIGHTNING. LIGHTNING STRIKES YESTERDAY/OVERNIGHT WERE REPORTED TO HAVE STARTED SOME FIRES. A VERY WARM START TO THE DAY TODAY WITH SOME LOCATIONS OVER THE NORTHERN SACRAMENTO VALLEY AND FOOTHILLS ONLY DROPPING TO THE UPPER 70S TO LOWER 80S. A LACK OF A DELTA BREEZE ALSO CONTRIBUTED TO THIS. HIGH TEMPERATURES TODAY COULD BE TRICKY AS CLOUDS MAY ACT TO LIMIT SOLAR HEATING. MAY NEED TO MAKE SOME ADJUSTMENTS TO AFTERNOON HIGHS. MORE WIDESPREAD CONVECTION IS EXPECTED ON TUESDAY AS THE LOW BEGINS TO SLOWLY SHIFT NORTHWARD. EK && .EXTENDED DISCUSSION (FRIDAY THROUGH MONDAY) SOME CHANGES TO THE FORECAST ON THURSDAY WITH INCREASED CHANCES OF SHOWERS AND THUNDERSTORMS OVER THE NORTHERN MOUNTAINS AND NORTHERN SACRAMENTO VALLEY THROUGH THE DAY AND INTO THE EARLY EVENING. MODELS HAVE SLOWED DOWN THE DEPARTURE OF THE UPPER LOW WITH IT LINGERING OVER NORTHERN CALIFORNIA THROUGH THE DAY THURSDAY. THERE IS FAIRLY GOOD AGREEMENT NOW BETWEEN THE ECMWF, THE GFS AND THE GEM WITH THE CORE OF THE LOW CENTERED AROUND SACRAMENTO BY LATE MORNING. CONVECTIVE ACTIVITY SHOULD BE LIMITED TO THE NORTHERN PORTION OF THE FORECAST AREA WITH DRIER MORE STABLE MOVING IN TO THE SOUTH. HIGH TEMPERATURES SHOULD BE AROUND NORMAL LEVELS BUT WILL DEPEND ON THE DEGREE OF CLEARING DURING THE DAY. THE LOW WILL SHOULD HAVE EXITED THE AREA BY LATE FRIDAY EVENING. THIS TIMING SUGGESTS THE LOW SHOULD WEAKEN AND EXIT THE REGION OVERNIGHT WITH DRY WEATHER FOR FRIDAY AND SATURDAY WITH STABLE SOUTHWEST FLOW. TEMPERATURES SHOULD BE AT TO A LITTLE BELOW NORMAL. EK && .AVIATION... SMOKE IN VICINITY OF WILDFIRES WILL CONTINUE TO CAUSE LOCAL IFR/MVFR VISIBILITIES SOUTH OF KBLU TO KAUN AND EAST OF KOVE. OTHERWISE, VFR CONDITIONS WILL PREVAIL ACROSS THE REGION. MAIN AVIATION CONCERN TODAY WILL BE ISOLATED TO SCATTERED SHOWER/THUNDERSTORM DEVELOPMENT BOTH IN THE MOUNTAINS AND OVER THE VALLEY WITH LOCAL MVFR/IFR CONDITIONS ASSOCIATED WITH STORMS. MOUNTAINS ARE MORE LIKELY TO HAVE SCATTERED COVERAGE OF -SHRA/-TSRA STARTING AFTER 18Z. VALLEY LOCATIONS WILL INITIALLY JUST HAVE ISOLATED -SHRA/-TSRA DURING MORNING AND AFTERNOON BUT THEN BECOME SCATTERED AFTER 00Z, ESPECIALLY NORTH OF I-80. LIGHT WINDS FOR ALL TAF SITES TODAY AROUND 10-12 KTS OR LESS, HOWEVER, ERRATIC GUSTY WINDS POSSIBLE IF THUNDERSTORMS DEVELOP. JBB && .STO WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 5 AM PDT THURSDAY NORTHEAST FOOTHILLS/SACRAMENTO VALLEY...WESTERN PLUMAS COUNTY/LASSEN PARK. RED FLAG WARNING UNTIL 11 PM PDT WEDNESDAY CLEAR LAKE/SOUTHERN LAKE COUNTY...MOTHERLODE...MOUNTAINS SOUTHWESTERN SHASTA COUNTY TO NORTHERN LAKE COUNTY...WEST SLOPE NORTHERN SIERRA NEVADA. RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 11 PM PDT WEDNESDAY CENTRAL SACRAMENTO VALLEY. RED FLAG WARNING FROM 2 PM THIS AFTERNOON TO 5 AM PDT THURSDAY BURNEY BASIN / EASTERN SHASTA COUNTY...NORTHERN SACRAMENTO VALLEY...SHASTA LAKE AREA / NORTHERN SHASTA COUNTY. && $$
AREA FORECAST DISCUSSION
NWS SAN DIEGO CA
950 AM PDT MON AUG 19 2013 .SYNOPSIS... UPPER LEVEL LOW PRESSURE WEST OF POINT CONCEPTION WILL DRAW A LIMITED AMOUNT OF MID LEVEL MONSOONAL MOISTURE INTO SOUTHERN CALIFORNIA WITH WIDELY SCATTERED THUNDERSTORMS FOR THE MOUNTAINS AND DESERTS OF SAN BERNARDINO AND RIVERSIDE COUNTIES THROUGH THIS EVENING. THE THUNDERSTORMS WILL PRODUCE LIGHTNING STRIKES...LOCALLY STRONG GUSTY WINDS...AND BRIEF HEAVY RAINFALL. AS THE TROUGH OF LOW PRESSURE WEAKENS AND MOVES INLAND THROUGH NORTHERN AND CENTRAL CALIFORNIA...DRIER SOUTHWEST FLOW ALOFT AND STRONGER ONSHORE FLOW WILL FOLLOW FOR TUESDAY AND WEDNESDAY...WEAKENING LATE IN THE WEEK. A GREATER INFLUX OF MONSOONAL MOISTURE IS POSSIBLE FOR NEXT WEEKEND THROUGH EARLY NEXT WEEK. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... REMAINDER OF TODAY THROUGH THIS EVENING... MOST OF SAN BERNARDINO COUNTY HAD NATURES ALARM CLOCK GO OFF THIS MORNING WITH THUNDERSTORMS BEGINNING SHORTLY BEFORE 0400 PDT AND CONTINUING UP UNTIL 0830 PDT. THE 19/12Z ANALYSES SHOWED THE LOW IS VERTICALLY STACKED AND CLOSED FROM 925 MB UP TO 200 MB. THIS WOULD ARGUE FOR A BAROTROPIC MODEL SOLUTION AND THE ONLY AVAILABLE MODELS AT THE FIELD OFFICE LEVEL ARE ALL BAROCLINIC. THOUGH THESE ARE SLOW IN MOVING THE LOW OUT TO THE NORTHEAST...2 KTS/LESS THAN 3 MPH...THEY MAY STILL BE TOO FAST. PLAN TO USE HRRR MODEL AS MODEL OF CHOICE FOR FIRST/SECOND PERIODS. ALREADY DID SOME QUICK MODIFICATIONS TO THE GRIDS AND ISSUED UPDATES TO THE ZONE FORECAST PRODUCTS. REMAINDER OF TONIGHT INTO WEDNESDAY... NO CHANGES ANTICIPATED TO CURRENT GRIDS/FORECAST AS THEY AGREE WITH LATEST GUIDANCE...ASSUMING THESE BAROCLINIC MODELS ARE NOT TOO FAST ON DRYING OUT AIR MASS. THURSDAY THROUGH SUNDAY...FROM EARLY MORNING DISCUSSION... A TROUGH OF LOW PRESSURE WILL DEVELOP OVER THE EASTERN PACIFIC. THIS MAY DRAW INCREASING MONSOONAL MOISTURE INTO SOUTHERN CALIFORNIA FOR NEXT WEEKEND INTO EARLY NEXT WEEK WITH SOME CONTINUING MODEL TO MODEL AND RUN TO RUN DIFFERENCES WITH THE DETAILS AND DEGREE OF THE POSSIBLE MOISTURE INFLUX. THE CURRENT FORECAST NOW SHOWS SLOWLY INCREASING POPS FOR THE MOUNTAINS AND DESERTS FOR SATURDAY THROUGH EARLY NEXT WEEK. && .HYDROLOGY... FLASH FLOOD THREAT IS LOW TO MODERATE...GROUND BASED GPS PRECIPITABLE WATER SENSORS ACROSS SW CALIFORNIA SHOW AMOUNTS RANGING FROM 1.2 INCHES WEST OF THE MOUNTAINS TO 1.6 INCHES OVER THE MOUNTAINS AND DESERTS. HOWEVER ONLY ONE STATION REPORTED ANY SIGNIFICANT RAIN EARLY THIS MORNING...HEAPS PEAK ON THE FRONT RANGE OF THE SAN BERNARDINO MOUNTAINS WITH 0.25 INCHES RAINFALL. ALTHOUGH RAINSHAFTS WERE OBSERVED OVER THE HIGH DESERTS...RAINFALL AMOUNTS THERE AS WELL AS ELSEWHERE HAVE GENERALLY BEEN LESS THAN 0.10 INCHES. THESE LOW NUMBERS PROBABLY DUE TO THE TRANSPORT WINDS...SOUTHEAST WINDS 15-25 MPH IN THE LOWER 15000 FEET...WHICH DOES NOT ALLOW THE CELLS TO STICK AROUND LONG ENOUGH TO DUMP MUCH MORE THAN WHAT HAS BEEN OBSERVED SO FAR. STILL HAVE TO WORRY ABOUT TRAINING OF CELLS AKA SEVERAL CYCLES OF THUNDERSTORMS MOVING ACROSS THE SAME AREA UNTIL EARLY EVENING HOURS TONIGHT...IF THIS DEVELOPS WOULD LIKELY PRODUCE FLASH FLOODING EAST/SOUTHEAST SLOPES OF MOUNTAINS WITH RUNOFF DOWN INTO DESERT VALLEY FLOORS. JUST MODIFIED THE 11AM THROUGH 11 PM GRIDS TO REFLECT MORE WIDESPREAD THUNDERSTORMS AND A LITTLE MORE RAIN. EVEN SO...STILL UNDERFORECASTING SREF POPS BY HALF SO THAT SGX GRIDS DO NOT CLASH TOO MUCH WITH NEIGHBORING OFFICES. WILL PROBABLY TWEAK A LITTLE MORE LATER THIS MORNING AND ISSUE ANOTHER QPS/UPDATED ESF. && .AVIATION... 191457Z...COAST/VALLEYS...STRATUS ABOUT 20 SM INLAND...WITH BASES 800-1200 FT MSL AND TOPS 1600-1800 FT MSL...WILL SLOWLY CLEAR TO THE COAST THROUGH 1900 UTC. 1900-20/0100 UTC...UNRESTRICTED VIS WITH SCT-FEW CLDS AOA 9000 FT MSL...IN ADDITION TO SCT-BKN CLDS 1200-1500 FT MSL LINGERING WITHIN 5 SM OF THE COAST...POSSIBLY IMPACTING KSAN...KCRQ AND KSNA WITH BKN CIGS AT TIMES. 20/0100-0700 UTC...STRATUS MOVING BACK INLAND...EVENTUALLY REACHING 20 SM INLAND BY 20/1400 UTC...WITH BASES AND TOPS SIMILAR TO THIS MORNING. MTNS/DESERTS...ISOLATED SHOWERS/TSTMS OVER WESTERN SAN BERNARDINO COUNTY WILL TAPER OFF THROUGH 1700 UTC. HOWEVER...THERE IS ANOTHER CHANCE OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING OVER THE RIVERSIDE AND SAN BERNARDINO MTNS AND HIGH DESERTS WITH BASES NEAR 9000 FT MSL AND TOPS TO 35000 FT MSL. THESE STORMS MAY PRODUCE SMALL HAIL...STRONG UPDRAFTS...2-5SM VIS IN HEAVY RAIN...AND LOCAL GUSTY SFC WINDS TO 40 KT. OTHERWISE...SCT-BKN CLDS AOA 9000 FT MSL AND UNRESTRICTED VIS THROUGH TUESDAY MORNING. && .MARINE... ASTRONOMICAL HIGH TIDES OF 7 FEET OR GREATER WILL OCCUR DURING THE EVENINGS THROUGH TUESDAY...INCLUDING A PEAK OF 7.2 FEET THIS EVENING. SOME VULNERABLE LOW-LYING AREAS ALONG THE COAST MAY EXPERIENCE SOME MINOR TIDAL OVERFLOW DURING TIMES OF HIGHEST TIDE. && .FIRE WEATHER... LOT OF DRY LIGHTNING BETWEEN 0400 AND 0800 PDT THIS MORNING...A CONSERVATIVE COUNT OF 500 STRIKES DURING THIS TIME PERIOD WITH AT LEAST 9 LIGHTNING STARTED FIRES ON THE SAN BERNARDINO NATIONAL FOREST. WITH EXCEPTION OF HEAPS PEAK...STATIONS WITH NEARBY LIGHTNING REPORTED NO RAINFALL OR AMOUNTS LESS THAN 0.10 INCHES. EXPECT A TEMPORARY BREAK IN THUNDERSTORM ACTIVITY UNTIL 1100 PDT THEN SCATTERED THUNDERSTORMS OVER MOUNTAINS AND DESERTS...MOVING NORTH NORTHWEST AROUND 15 MPH. MOST OF THESE SHOULD BE A MIXTURE OF WET AND DRY...HAVE LAL OF 3 AND 4 FOR REMAINDER OF TODAY/THIS EVENING. STILL NO WIDESPREAD SIGNIFICANT RAINFALL AMOUNTS EXPECTED DUE TO SPEED OF MOVEMENT AND DRY LAYER FROM BELOW THUNDERSTORM BASES AND TOP OF ANY MARINE AIR INFLUENCE...ROUGHLY 10,000 FT TO 2000 FT MSL....WHICH PRETTY MUCH COVERS ALL OF THE MOUNTAINS AND DESERTS. FOR TUESDAY AND WEDNESDAY...THE LOW IS MOVING EVER SO SLOWLY TOWARDS THE NORTHEAST...ASSUMING THE MODELS ARE CORRECT AND IT`S STILL NOT SITTING IN THE SAME POSITIONS OR FURTHER SOUTH. SO BASED ON MODEL MOVEMENT SOUTHWEST CALIFORNIA SHOULD BE UNDER MORE STABLE AND SOMEWHAT DRIER AIRMASS AND PREVAILING SOUTHWEST FLOW. PERHAPS NO NEW FIRE STARTS BUT A DRIER AND POTENTIALLY BREEZIER PATTERN WOULD FAN TO LIFE ANY SLEEPERS AND INCREASE FIRE ACTIVITY ACROSS ONGOING FIRES. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC/FIRE WEATHER...BALFOUR AVIATION/MARINE...HARRISON SHORT TERM WARNINGS/STATEMENTS...HARRISON/JJT
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1043 AM MDT MON AUG 19 2013 .UPDATE... ISSUED AT 1037 AM MDT MON AUG 19 2013 SUNSHINE THIS MORNING WILL PROVIDE GOOD SURFACE HEATING TO START THE CONVECTIVE CLOUD BUILDUPS OVER THE MTNS BY LATE MORNING. 12Z MODELS REMAIN HIGHER TERRAIN-CENTRIC WITH THEIR PRECIPITATION FORECAST THIS AFTERNOON AND EVENING. NOT TOO SURPRISING WITH THE UPPER RIDGE OVERHEAD AND LIGHT WINDS ALOFT. STORMS THAT DO DEVELOP THIS AFTERNOON WILL SHOW LITTLE MOVEMENT AND LIKELY COLLAPSE UPON THEMSELVES FOR THE POTENTIAL OF SOME GUSTY OUTFLOW WINDS AND ACCENTUATED BY A DRIER SUB-CLOUD LAYER. ONE AREA TO WATCH FOR HEAVY RAIN POTENTIAL IS SE UT ACROSS THE SW CO. VORTICITY AXIS EXTENDS ACROSS THIS AREA FROM A WEAK SHORTWAVE MOVING UP THE NV/UT BORDER AND MAY SERVE AS A BIT OF A FOCUS. THIS ALSO IS AN AXIS OF HIGHER PRECIPITABLE WATER ESTIMATES OF 0.8 TO 1.0 INCH. WILL ADJUST POPS UPWARDS A BIT FOR SE UT/SW CO THIS AFTERNOON AS A RESULT. UPDATE ISSUED AT 830 AM MDT MON AUG 19 2013 QUICK UPDATE TO THE GRIDDED FORECAST TO BETTER REFLECT THE CURRENT SUNNY/MOSTLY SUNNY CONDITIONS ACROSS MOST OF FORECAST AREA EARLY THIS MORNING. EXCEPTION IS SOME ALTOCUMULUS CLOUDS OVER SE UT LEFT OVER FROM LAST NIGHT AND WHERE THE RAP MODEL PUTS A WEAK VORTICITY MAX. CURRENT FORECAST FOR THIS AFTERNOON SEEMS ON TRACK PER QUICK LOOK AT THE LATEST RAP/HRRR MODELS. && .SHORT TERM...(TODAY THROUGH TUESDAY) 300 AM MDT MON AUG 19 2013 HIGH PRESSURE WILL REMAIN ANCHORED OVER THE REGION FOR THE NEXT SEVERAL DAYS. MOISTURE WORKING NORTHWARD WILL BRING ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS THIS AFTERNOON AND EVENING...WITH THE FOCUS TODAY GENERALLY SOUTH OF INTERSTATE 70. STORMS WILL INITIALLY FIRE ALONG THE HIGHER TERRAIN...WITH ACTIVITY DRIFTING OFF OVER THE VALLEYS LATE THIS AFTERNOON AND EVENING...WITH AN EMPHASIS ON DRIFT. WINDS ALOFT WILL BE WEAK WITH THE RIDGE DIRECTLY OVERHEAD AND POTENTIAL FOR LOCALLY HEAVY RAINFALL WILL BE UP A BIT WITH SLOW STORM MOTIONS. TEMPERATURES WILL BE RUNNING NEAR SEASONAL NORMS WITH LIGHT WINDS OUTSIDE OF CONVECTIVE GUSTS TO NEAR 40 MPH WITH THE STRONGER STORMS. A STRONGER SURGE OF SUBTROPICAL MOISTURE CONTINUES TO WORK INTO THE GREAT BASIN AND THEN LEAKS EASTWARD INTO TUESDAY FOR AN UPTURN IN SHOWERS AND THUNDERSTORMS. THE SHEARED ENERGY FROM THE BAJA DISTURBANCE IS PROGGED TO STAY WELL WEST OF THIS CWA WITH TIME HEIGHT SECTIONS SHOWING LITTLE ORGANIZED DYNAMICAL LIFT. STILL PRECIPITABLE WATER VALUES CLIMB TO AN INCH OVER EASTERN UTAH AND FAR WESTERN COLORADO. BROKEN TO OVERCAST SKIES MAY LIMIT OR DELAY AFTERNOON HEATING AND INSTABILITY SOMEWHAT. SLOW STORM MOTION WILL PRODUCE LOCALLY HEAVY RAIN AND POTENTIAL RUNOFF PROBLEMS. A RELATIVELY DRY NEAR- SURFACE LAYER WILL ALSO ASSIST WITH ENHANCED LOCAL OUTFLOW WINDS. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) 300 AM MDT MON AUG 19 2013 BOUNDARY INTERACTION MAY PRODUCE ISOLATED NOCTURNAL CONVECTION INTO WEDNESDAY MORNING. THE 593 HIGH REBOUNDS WESTWARD BACK TO NEAR THE FOUR CORNERS. BOTH THE GFS AND NAM ERODE PRECIPITABLE WATER VALUES SOMEWHAT UNDER THE HIGH. SUBSIDENCE WILL ALSO CAP LATE DAY CONVECTION A BIT COMPARED TO TUESDAY. STILL ALL MTN RANGES WILL LIKELY FIRE SOME AFTERNOON STORMS. STORM MOTION REMAINS SLOW FOR A CONTINUED THREAT OF LOCALLY HEAVY SHOWERS. MOISTURE WORKING NORTHWARD ALONG THE WESTERN EDGE OF HIGH PRESSURE CENTERED ACROSS THE CENTRAL PLAINS WILL KEEP CONDITIONS UNSETTLED AS WE MOVE THROUGH THE WEEK AND INTO THE WEEKEND. HARD TO PIN POINT ANY INDIVIDUAL WAVE IN THIS PATTERN FOR ENHANCED POTENTIAL...SO FOR NOW WILL CONTINUE WITH THE BROAD BRUSH APPROACH OF DAILY CONVECTION...PRIMARILY FOCUSED ON THE AFTERNOON AND EVENING HOURS. TEMPERATURES WILL BE RUNNING NEAR SEASONAL NORMS THROUGH THE PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1037 AM MDT MON AUG 19 2013 SCATTERED SHOWERS AND THUNDERSTORMS WILL AGAIN DEVELOP ACROSS EASTERN UTAH AND WESTERN COLORADO THIS AFTERNOON AND EVENING. THE STORMS WILL BE MOST NUMEROUS SOUTH AND EAST OF A LINE FROM K4HV TO KEGE...ESPECIALLY BETWEEN 20Z THIS AFTERNOON AND 03Z THIS EVENING. OUTSIDE OF THIS WINDOW...STORMS WILL BE MORE ISOLATED IN NATURE. EXPECT BRIEF HEAVY RAIN...SMALL HAIL AND GUSTY OUTFLOW WINDS TO 40 MPH IN THE VICINITY OF SHOWERS WITH BRIEF MOUNTAIN OBSCURATIONS POSSIBLE. STORMS DISSIPATE AFTER 03Z THIS EVENING WITH VFR CONDS PREVAILING AT ALL TERMINAL SITES. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...NONE. UT...NONE. && $$ UPDATE...JAD SHORT TERM...JDC/JOE LONG TERM...JOE/JDC AVIATION...TGJT
AREA FORECAST DISCUSSION
NWS POCATELLO ID
222 PM MDT MON AUG 19 2013 .DISCUSSION...STRONG UPPER LOW REMAINS OFF CALIFORNIA COAST WITH MOISTURE STREAMING NORTH THROUGH GREAT BASIN. SHORTWAVE AXIS HAS MOVED THROUGH PANHANDLE INTO MONTANA EARLY THIS AFTERNOON...WHICH HAS KEPT MOISTURE SURGE LIMITED. CONVECTION SO FAR LIMITED TO AREAS SOUTH OF STATE LINE BUT HAVE LEFT WEAK POPS NORTH OF BORDER INTO SOUTHERN HIGHLANDS FOR OVERNIGHT. HRRR PUSHES CONVECTION NORTH INTO THE REGION BY LATE AFTERNOON THEN SLOWLY SPREADS NORTHEAST AFTER MIDNIGHT. GFS LENDS SUPPORT TO THIS IDEA BUT NAM LESS SO. MOISTURE SURGE CONTINUES INTO MIDWEEK WITH STRONG GRADIENT LAYING ACROSS EASTERN IDAHO MIDDAY TUESDAY...THEN GRADIENT PUSHING WELL NORTH OF FORECAST AREA FOR WEDNESDAY AND BEYOND. STILL SOME QUESTION AS TO HOW FAR NORTH CONVECTION WILL PUSH ON TUESDAY AFTERNOON WITH SUBSEQUENT IMPACT ON FIRE HEADLINES. SEE DISCUSSION BELOW. OTHERWISE BEST CHANCE FOR SIGNIFICANT COVERAGE OF STORMS APPEARS TO BE ON WEDNESDAY WITH PW OVER AN INCH MOST AREAS. COULD SEE LOCALLY HEAVY RAINFALL AND WILL NOT BE SURPRISED IF FLASH FLOOD WATCH MAY BE NECESSARY IN ADDITION TO RED FLAG FOR FIRE CONCERNS...ESPECIALLY IN VICINITY OF RECENT BURN SCARS LIKE BEAVER CREEK/LODGEPOLE/STATE FIRES IN URBAN/WILDLAND INTERFACE AREAS. BOTH GFS AND ECMWF CONTINUE IDEA OF WEAKENING UPPER LOW WEDNESDAY NIGHT INTO THURSDAY AND EJECTING LOW NORTHEAST THROUGH PACNW/PANHANDLE ON FRIDAY. SOME IDEA OF A DRY SLOT ON FRIDAY...THEN SOUTH FLOW CONTINUES THROUGH THE GREAT BASIN INTO EASTERN IDAHO THROUGH THE REMAINDER OF THE WEEKEND WITH STRONG HIGH OVER GREAT PLAINS AND AMPLIFYING TROUGH JUST OFF PACIFIC COAST. WILL KEEP SOME MENTION OF THUNDERSTORMS OVER HIGHER ELEVATIONS FRIDAY THROUGH THE WEEKEND. DMH && .AVIATION...SMOKE AT KSUN WILL CONTINUE TO BE THE GREATEST IMPACT. LOOK FOR IFR VISIBILITIES AGAIN TONIGHT THROUGH TOMORROW MORNING. LOOK FOR ISOLATED THUNDERSTORMS ACROSS OUR SOUTHERN AREAS LATE THIS AFTERNOON INTO EARLY EVENING BRINGING VICINITY THUNDERSTORMS FOR KBYI AND TO AN LESSER EXTENT KPIH. TOMORROW AFTERNOON LOOK FOR A BETTER CHANCE FOR VICINITY THUNDERSTORMS PARTICULARLY FOR KBYI AND KSUN. WYATT && .FIRE WEATHER...A RED FLAG HAS BEEN CONTINUED FOR ZONE 475 THROUGH EARLY THIS EVENING. RELATIVE HUMIDITY HAS ALREADY GONE BELOW 15 PERCENT WITH WINDS IN THE UPPER TEENS TO LOWER TWENTIES. FIRE ZONES 422 AND 475 ARE RUNNING SLIGHTLY STRONGER WINDS BUT HAVE SLIGHTLY HIGHER RELATIVE HUMIDITY WITH MOISTURE MOVING UP FROM THE SOUTH. EXPECT AFTERNOON ISOLATED THUNDERSTORMS ACROSS THE SOUTHERN HIGHLANDS TODAY. A FIRE WEATHER WATCH FOR SCATTERED SHOWERS AND THUNDERSTORMS IS CONTINUED FOR TUESDAY AFTERNOON THROUGH THURSDAY. HAVE HELD OFF ON UPGRADING TO A RED FLAG FOR TUESDAY AS IT LOOKS MARGINAL FOR SCATTERED AFTERNOON THUNDERSTORMS AT THIS POINT. WEDNESDAY AND THURSDAY AFTERNOONS STILL LOOK LIKE A RED FLAG WARNING WILL BE NEEDED FOR SCATTERED TO NUMEROUS THUNDERSTORMS. A FLASH FLOOD WATCH FOR WEDNESDAY AFTERNOON MAY BE NEEDED AS WELL FOR THE MOUNTAIN ZONES PARTICULARLY FOR RECENT BURN AREAS. MODELS SHOW SLIGHT THUNDERSTORM CHANCES FOR OUR NORTHERN AREAS FRIDAY AFTERNOON IN SOUTHWEST FLOW. SATURDAY LOOKS SLIGHTLY DRIER BEFORE ANOTHER SYSTEM STARTS TO APPROACH THE AREA BRINGING BACK BETTER PRECIPITATION CHANCES FOR SUNDAY AND MONDAY. WYATT && .AIR STAGNATION...AREAS OF SMOKE WILL REMAIN IN THE FORECAST OVER THE CENTRAL MOUNTAINS WHILE LARGE FIRES CONTINUE TO BURN. INCREASING MOISTURE OVER THE NEXT FEW DAYS WILL ALLOW THUNDERSTORMS TO FORM. OVERALL IMPACT TOUGH TO SAY WITH POTENTIAL FOR BOTH NEW STARTS DUE TO LIGHTNING AND LOCALLY HEAVY RAIN WHICH MAY HELP CURRENT FIRE SITATION. IDAHO DEQ HAS LIFTED AIR QUALITY STATEMENT FOR CUSTER COUNTY WHILE CONTINUING FOR BLAINE AND HAVE ISSUED UPDATED STATEMENTS. DMH && .PIH WATCHES/WARNINGS/ADVISORIES... FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH THURSDAY EVENING IDZ413-427. FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH THURSDAY EVENING IDZ410-425. RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING IDZ475. FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH THURSDAY EVENING IDZ422-475-476. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
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
AREA FORECAST DISCUSSION
NWS GOODLAND KS
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
AREA FORECAST DISCUSSION
NWS LOUISVILLE KY
132 PM EDT Mon Aug 19 2013 ...Updated Aviation Discussion... ...Forecast Update... Issued at 1107 AM EDT Mon Aug 19 2013 Fog continues to mix out across the southern forecast area this morning. In most locations, the fog has transitioned over to a low stratus deck which will take some time to mix out more fully. We expect that to occur around lunch time or early this afternoon. Cu field has become better defined across southern KY this morning despite having a bit more capping aloft. A few isolated showers will be possible mainly along and SE of the BG Parkway. Additional isolated showers/storms will be possible later this afternoon. Forcing is fairly weak from a dynamical standpoint, but differential heating is probably going to be main forcing mechanism this afternoon. Temperatures are currently in the lower 70s across the south, with a belt of mid-upper 70s along and just north of the Ohio River. Obviously the thicker cloud cover to the south will augment the solar insolation a bit this afternoon which will likely lead to a N-S temperature gradient. Highs in the 80-85 degree range in areas from the KY Parkways and northward still look good. Lower 80s down across the south and southeastern sections are still attainable, but will probably occur a little later in the afternoon due to the cloud cover delaying insolation. Update issued at 530 AM EDT Mon Aug 19 2013 Updated the forecast to remove areas of fog with patchy dense fog from southeast Indiana and the Bluegrass region of KY. Mid level clouds and lesser low level moisture than central and southern KY (where patches of dense fog have been reported) have limited fog formation over southeast Indiana and the Bluegrass. Downgraded this area to just patchy fog for the rest of the pre-dawn hours. Issued an SPS for portions of south and central KY where patchy dense fog has been reported and where it rained yesterday (which should be fog prone). Few-sct mid level clouds continue to move over this area improving fog at times so feel dense fog coverage will remain patchy. .SHORT TERM (Now through Tuesday)... Issued at 330 AM EDT Mon Aug 19 2013 The main forecast concern in the short term will be fog this morning. A very moist low level atmosphere along with very light or nearly calm winds have created an ideal environment for fog formation which we`ve already seen develop in our area. The worst fog spots remain over southern IL/western KY and over southwest Ohio. The 5Z RAP model has these fog areas handled well and expect them to expand into central KY and portions of southeast IN. Low clouds will also accompany the fog as soundings indicate a shallow layer of trapped moisture under a weak inversion. With these thoughts in mind, think that most locations over southern IN and central KY will see areas of fog this morning. Some locations over central KY and southeast IN will probably see patches of dense fog as well assuming the low clouds don`t inhibit fog density too much. Will highlight the patchy dense fog in the HWO this morning and monitor closely in case it becomes more widespread and an SPS or dense fog advisory is need. For the rest of the day, fog should burn off fairly quickly after sunrise. With an upper trough passing through the region, can`t rule out an isld shower over portions of south and east central KY. However, did scale the area of potential precip back a bit. High temperatures should reach the low to mid 80s this afternoon. Tonight a second upper trough will settle into the mid Mississippi River Valley. Some fog may be possible but not as widespread as this morning. Will continue inherited patchy fog mainly in river valleys. Lows tonight will be in the mid 60s. For Tues, expect a 20% chance of showers/t-storms to expand from south to north over the area throughout the day as a vort wave on the eastern side of the upper trough push north through our area. Any convection would be on the weak side. Tuesday afternoon high temps should be in the low to mid 80s with southern Indiana being the hottest due to a longer period of sunshine before clouds/isld convection move in. .LONG TERM (Tuesday Night through Sunday)... Issued at 311 AM EDT Mon Aug 19 2013 The models have finally come into agreement with a mid-level low that forms over the Ohio Valley at the start of this forecast period. This cutoff low hangs out in the region through Thursday night when it undergoes a transformation into an open wave in response to an approaching shortwave. This shortwave rides around the periphery of a stout ridge building in over the Plains and looks to exit the forecast area by early Saturday. The ridge continues to build in from the west, giving us dry conditions through the end of the weekend and into early next week. Tuesday night through Thursday: For this issuance, have introduced slight chance PoPs for Tuesday night as the low establishes itself overhead and surface southerly flow allows for moisture to be pulled in. Chance PoPs continues for Wednesday as daytime heating assists in convection across the area. With the loss of daytime heating and in conjunction with general model consensus, have kept PoPs out overnight Wednesday into early Thursday. As the low is depicted to begin traversing eastward Thursday, have only slight chance during the day with the primary focus for possible convection more toward eastern KY. The models have the low slowly but surely progressing eastward during this time frame and am a little skeptical on its speed. How quickly the low exits will depend on the timing of a weak frontal boundary attempting to lay out across the southern Great Lakes by Thursday night. Thursday night through Friday night: Have gone with slight chance PoPs strictly across the northern sections as the alluded to frontal boundary approaches from the north. The front stalls well to our north and does not currently appear to be a factor for us beyond Friday. The aforementioned shortwave swings around the region Friday, hence the slight to chance PoPs under diurnally-driven conditions. Again, skepticism sets in for the timing of it all as it seems to really move through a little too quickly. For now, have kept the area dry Friday night until a better handle on the progression of everything plays out. Temperatures will be more difficult to predict Tuesday night through Friday night as cloudy skies and/or rain will obviously wreck havoc. What can be said with confidence is that highs will continue to run slightly below normal and lows will flirt with normal. Saturday through Sunday: With that ridge building in, we`ll begin to see real signs of summer return as temperatures look to rebound back toward normal and partly to mostly sunny skies prevail. && .AVIATION (18Z TAF Update)... Issued at 131 PM EDT Mon Aug 19 2013 VFR conditions are expected through much of the period. Some scattered showers and storms will be possible this afternoon across the Bluegrass region that could affect the KLEX area. For now, will carry a VCSH group through the afternoon. Surface winds are expected to be light and variable. VFR conditions are expected this evening and into the overnight period. However, guidance suggests fog is likely again at KBWG and KLEX, so will carry some tempo IFR vsbys between 20/08-12Z at KBWG and KLEX. KSDF should remain VFR overnight with some patchy haze possible toward 20/12Z. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ Update.........MJ Short Term.....AMS Long Term......lg Aviation.......MJ
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
422 PM EDT MON AUG 19 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 422 PM EDT MON AUG 19 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW ZONAL FLOW ACROSS MUCH OF SRN CANADA. SHORTWAVE TROF THAT WAS OVER MT/SRN SASKATCHEWAN 24HRS AGO IS NOW OVER THE UPPER LAKES THOUGH MUCH OF THE ENERGY APPEARS TO BE SETTLING SSE INTO THE WEAKENING REMNANT OF THE TROF THAT HAS BEEN OVER THE LOWER MISSISSIPPI VALLEY THE LAST FEW DAYS. WAVE PRODUCED A CLUSTER OF SHRA/TSRA OVER WRN LAKE SUPERIOR THIS MORNING. THE SHRA RAPIDLY DIMINISHED AS THEY APPROACHED WRN UPPER MI AND DISSIPATED SOON AFTER REACHING THAT AREA. SO...FAR NO NEW SHRA/TSRA HAVE DEVELOPED WITH DAYTIME HEATING. LATEST SPC MESOANALYSIS SHOWS MLCAPE OF 500-1000J/KG OVER ROUGHLY THE W HALF OF UPPER MI. VIS SATELLITE IMAGERY SHOWS CU DEVELOPING OVER THE LAST COUPLE OF HRS...AND LATEST OBS ALONG THE SHORE INDICATE LAKE BREEZE JUST BEGINNING TO DEVELOP OFF LAKE SUPERIOR. PERHAPS A FEW SHRA/TSRA MAY YET DEVELOP OVER THE NEXT COUPLE OF HRS AS LAKE BREEZE MAKES SOME INLAND PROGRESS. SINCE LATEST HIGH RES RAPID REFRESH MODEL STILL GENERATES SOME CONVECTION OVER THE NCNTRL LATE THIS AFTN...WILL HOLD ONTO SCHC POPS FOR THE NEXT SEVERAL HRS. IF ANY SHRA/TSRA DO DEVELOP...THEY WILL DISSIPATE WITH LOSS OF DAYTIME HEATING...ESPECIALLY SINCE HEIGHTS ARE IN THE PROCESS OF STEADILY RISING AND DEEP LAYER QVECTOR DIVERGENCE IS DEVELOPING. THERE IS SOME THETA-E ADVECTION OVERNIGHT...AND THE GEM SUGGESTS SOME ISOLD CONVECTION LATE TONIGHT/TUE MORNING AT LEADING EDGE OF THETA-E AXIS APPROACHING WRN UPPER MI. HOWEVER...WITH 850MB WINDS ANTICYCLONIC AND NOT MUCH OF A LOW-LEVEL JET...POTENTIAL OF ANY ISOLD CONVECTION LATE SEEMS VERY UNLIKELY. WILL CARRY DRY FCST THRU THE OVERNIGHT. ALTHOUGH SKIES WILL TURN MOSTLY CLEAR...A LIGHT BUT STEADY SW WIND AND INCREASED COLUMN MOISTURE WILL WORK TO LIMIT THE DIURNAL TEMP FALL. UNDER S TO SW WINDS...THE HIGHEST MIN TEMPS WILL BE IN THE DOWNSLOPE AREAS NEAR LAKE SUPERIOR OVER THE W HALF. EXPECT MINS IN THE MID 60S THERE. INLAND...MID 50S TO AROUND 60F SHOULD BE THE RULE. ON TUE...PRES GRADIENT TIGHTENS A BIT BTWN SFC HIGH OVER THE MID ATLANTIC STATES AND A LOW PRES TROF MOVING ACROSS THE NRN PLAINS/SCNTRL CANADA. STRENGTHENING SW FLOW WILL BRING AN INCREASE IN LOW-LEVEL DWPTS TUE...RESULTING IN A MUCH MORE UNCOMFORTABLE DAY. MIXING TOWARD 800MB ON FCST SOUNDINGS SUGGESTS MAX TEMPS EASILY INTO THE MID/UPPER 80S. STRONGER SW WINDS WILL PREVENT LAKE BREEZE DEVELOPMENT OFF LAKE SUPERIOR AND SHOULD LEAD TO SOME OF THE WARMEST READINGS IN THE DOWNSLOPE AREAS NEAR THE LAKE. EXPECT SOME LOCATIONS TO REACH OR JUST EXCEED 90F. S/SW WINDS WILL KEEP CONDITIONS COOLER NEAR LAKE MICHIGAN. COMBINATION OF TEMPS WELL INTO THE 80S AND HIGHER DWPTS INTO THE 60S WILL MAKE TUE THE MOST UNCOMFORTABLE DAY SINCE THE HOT WEATHER STRETCH IN MID JULY. NAM SHOWS MLCAPE INCREASING TO 2000-3000J/KG TUE AFTN WHILE THE GFS IS LOWER IN THE 1000-2000J/KG RANGE. LACK OF LAKE BREEEZE DEVELOPMENT OFF LAKE SUPERIOR WILL BE ONE MISSING FORCING MECHANISM TO TRIGGER CONVECTION. SINCE THERE ARE HINTS OF A SUBTLE SHORTWAVE MOVING TOWARD THE UPPER LAKES...OPTED TO MAINTAIN SCHC POPS OVER PORTIONS OF CNTRL UPPER MI WHERE THERE IS SOME LOW-LEVEL CONVERGENCE AS A RESULT OF LAKE MICHIGAN LAKE BREEZE COMPONENT. IN THE ABSENCE OF ANY SHORTWAVE...TUE WILL LIKELY END UP DRY ACROSS THE BOARD. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 422 PM EDT MON AUG 19 2013 NORTHERN STREAM UPPER TROUGH WILL SLIDE THROUGH THE AREA DURING THE FIRST PART OF THE LONG TERM PERIOD AND LEAD TO A DECENT CHANCE OF RAIN OVER THE AREA WEDNESDAY. FIRST FOR TUESDAY NIGHT...THERE MAY BE SOME SHOWERS/THUNDERSTORMS OVER LAKE SUPERIOR ON AHEAD OF THE COLD FRONT. THIS A CONTINUATION OF THE CONVECTION THAT DEVELOPS IN SOUTHWEST ONTARIO AND NORTHEAST MINNESOTA FROM THE AFTERNOON AND A WEAK SHORTWAVE MOVING EAST ACROSS LAKE SUPERIOR. IN ADDITION...THIS IS ALSO THE AREA OF THE STRENGTHENING LOW LEVEL JET AND 850-700MB THERMAL RIDGE. WITH STORM MOTIONS TO THE EAST...WOULD THINK ISLE ROYALE AND NORTHERN LAKE SUPERIOR WOULD HAVE THE BEST SHOT OF SEEING PRECIPITATION...BUT IT COULD BRUSH THE KEWEENAW PENINSULA. ON WEDNESDAY...THE MAIN SHORTWAVE WILL BE MOVING THROUGH SOUTHWEST ONTARIO AND BE DISCONNECTED FROM THE COLD FRONT MOVING EAST ACROSS WESTERN LAKE SUPERIOR ON WEDNESDAY MORNING. BUT...THERE ARE HINTS THAT A SECOND WEAKER WAVE WILL BE SLIDING EAST ACROSS NORTHERN WISCONSIN AND WESTERN UPPER MICHIGAN IN THE AFTERNOON. IF THIS OCCURS...IT WOULD ASSIST WITH CONVECTIVE DEVELOPMENT AS THE COLD FRONT MOVES THROUGH WESTERN/CENTRAL U.P. DURING THE DAY WEDNESDAY. MODELS SEEM TO HAVE SPED IT UP A TOUCH WITH IT MOVING THROUGH THE WESTERN U.P. IN THE LATE MORNING OR EARLY AFTERNOON AND THEN THE CENTRAL U.P. IN THE MID AFTERNOON HOURS. IT THEN EXITS THE AREA OVER LAKE MICHIGAN DURING THE EVENING. WITH THE WARM...HUMID AIRMASS...INSTABILITY WILL BE PRETTY GOOD FOR U.P. STANDARDS (MLCAPE VALUES OF 1500-3000 J/KG DEPENDING ON THE MODEL) WHICH ARE AIDED BY STEEP MID LEVEL LAPSE RATES (AROUND 7-7.5C/KM FROM 850-700MB). THIS HELPS BOOST HAIL CAPE VALUES TOWARDS 800 J/KG...BUT WITH FREEZING LEVELS AROUND 12KFT...IT MAY COUNTERACT THE HAIL POTENTIAL. 0-6KM AND EFFECTIVE SHEAR VALUES ARE MARGINAL FOR THUNDERSTORM ORGANIZATION (ONLY AROUND 20-25KTS) AND FAIRLY UNIDIRECTIONAL. 09Z SREF RUN AGREES WITH THAT BASIC IDEA AND ONLY HAS 50 PERCENT PROBS FOR EFFECTIVE SHEAR OVER 30KTS. BUT WITH THE COLD FRONT...WOULD EXPECT SOME CLUSTERS OR LINE OF STORMS TO FORM. STORM MOTION AND MOVEMENT OF THE COLD FRONT WOULD SUPPORT AN EAST TO SOUTHEAST MOVEMENT OF THE THUNDERSTORMS. FINALLY...THINK THERE WILL BE SOME WIND THREAT DUE TO DCAPE VALUES PEAKING OVER THE SOUTH CENTRAL WHERE THERE WILL BE LESS OF AN INFLUENCE OF CLOUDS TO AID DESTABILIZATION. THUS...HAVE TRENDED SOME LOCATIONS UP TO SHOWERS/THUNDERSTORMS LIKELY OVER THE CENTRAL AND WEST-CENTRAL IN THE AFTERNOON. SPC HAS WESTERN/CENTRAL PORTIONS OF THE U.P. IN A SLIGHT RISK AND THAT SEEMS REASONABLE AT THIS POINT ALTHOUGH THE LIMITED SHEAR LEAVES SOME CONCERN FOR WIDESPREAD SEVERE WEATHER. THE WARM AIR AHEAD OF THE COLD FRONT WILL PRODUCE ANOTHER WARM DAY...ESPECIALLY OVER THE CENTRAL/EAST (HIGHS IN UPPER 80S OR LOWER 90S). THE WEST MAY BE LIMITED BY MID CLOUDS MOVING IN AHEAD OF THE COLD FRONT AND HAVE HIGHS IN THE 80S THERE. AS THE UPPER TROUGH SHIFT EAST ON THURSDAY...HIGH PRESSURE WILL BUILD OVER THE AREA WHILE AN UPPER RIDGE BUILD OVER THE NORTH CENTRAL CONUS AND CENTRAL CANADA. WITH THIS HIGH IN PLACE...EXPECT ANOTHER PERIOD OF DRIER WEATHER INTO THE FIRST PART OF THE WEEKEND. A SECONDARY SHORTWAVE MOVES THROUGH ON THURSDAY...BUT WITH THE DRY ATMOSPHERE...DON/T EXPECT MUCH MORE THAN PASSING MID CLOUDS. TEMPERATURES DURING THE LONG TERM PERIOD WILL BE COOLEST ON THURSDAY/FRIDAY BEHIND THE COLD FRONT (HIGHS IN THE 70S)...BUT THEN AS THE HIGH SHIFTS EAST SATURDAY...SOUTH-SOUTHWEST LOW LEVEL FLOW WILL ALLOW TEMPERATURES TO WARM BACK ABOVE NORMAL FOR THE WEEKEND (HIGHS AROUND 80S...ALTHOUGH THE LATEST ECMWF IS SHOWING VALUES NEAR 90). MODELS DIFFER SOMEWHAT FOR SATURDAY INTO MONDAY...DUE TO CONVECTION FIRING OR NOT FIRING ALONG THE REMNANTS OF THE COLD FRONT STRETCHING FROM SOUTHERN MINNESOTA THROUGH THE OHIO RIVER VALLEY. THE ECMWF HAS BEEN SHOWING THIS FRONT SLOWLY PUSHING NORTH AS A WARM FRONT THROUGH THE WEEKEND...WHICH WOULD GIVE BETTER CHANCES FOR PRECIPITATION FOR THE END OF THE WEEKEND INTO THE BEGINNING OF NEXT WEEK. THE GFS ON THE OTHERHAND AS BEEN SHOWING A STRONGER HIGH LINGERING OVER THE AREA AND KEEPING THE BROAD AREA OF LOW PRESSURE FOCUSED IN THE DAKOTAS (SIMILAR TO WHAT WE HAVE EXPERIENCED OVER THE LAST COUPLE OF DAYS). BOTH MODELS HAVE BEEN VARYING ON THEIR SOLUTIONS OVER THE LAST COUPLE OF DAYS...SO CONFIDENCE IS LIMITED THIS FAR OUT. THEREFORE...WILL FOLLOW A GENERAL CONSENSUS WITH CHANCE OR SLIGHT CHANCE POPS FOR THE WEEKEND INTO EARLY NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 128 PM EDT MON AUG 19 2013 WITH RELATIVELY DRY LOW-LEVELS PERSISTING...VFR CONDITIONS ARE EXPECTED THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. A WEAK DISTURBANCE PASSING OVER THE UPPER LAKES COMBINED WITH BUILDING DAYTIME INSTABILITY COULD SPARK ISOLD CONVECTION THIS AFTN WHICH MIGHT AFFECT KIWD/KSAW. HOWEVER...CONFIDENCE IN DEVELOPMENT/LOCATION OF ANY SHRA/TSRA IS VERY LOW. SO...NO MENTION OF SHRA/TSRA WAS INCLUDED IN THIS FCST. AS WITH RECENT NIGHTS...INCREASING SW WINDS TONIGHT ABOVE NOCTURNAL INVERSION WILL APPROACH LLWS CRITERIA. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 422 PM EDT MON AUG 19 2013 OVERALL...EXPECT WINDS LESS THAN 20KT THRU THE PERIOD AS A RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE GREAT LAKES REGION. ONE PERIOD OF STRONGER WINDS (GUSTS TO 20-25KT) MAY OCCUR TUE NIGHT AS PRES GRADIENT TIGHTENS DUE TO APPROACHING COLD FRONT. THE ARRIVAL OF MORE HUMID AIR TUE/WED MAY RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL BE MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE. ANY FOG WILL DISSIPATE WED AFTN/EVENING FOLLOWING A COLD FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...SRF AVIATION...ROLFSON MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
129 PM EDT MON AUG 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 359 AM EDT MON AUG 19 2013 00Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW A ZONAL FLOW OVER SRN CANADA TO THE N OF UPR RDG EXTENDING FM THE WRN PLAINS INTO THE GREAT LKS. THE WX OVER UPR MI IS QUIET EARLY THIS MRNG...WITH DRY/STABLE AIRMASS DEPICTED ON THE 00Z MPX/GRB RAOBS DOMINATING THE AREA. THERE ARE 2 SHRTWVS EMBEDDED IN THE ZONAL FLOW THAT ARE OF CONCERN. THE FIRST OF THESE IS MOVING EWD THRU THE DAKOTAS AND ARPCHG NW MN...ACCOMPANIED BY SCT SHRA/TS. THE SECOND IS MOVING THRU NW ONTARIO WITH A CLUSTER OF SHRA/TS NW OF LK NIPIGON...BUT SOME ISOLD SHRA/TS WITHIN THE COMMA TAIL OF THIS FEATURE EXTEND FARTHER S INTO THE MN ARROWHEAD UNDER SOME H85-5 QVECTOR CNVGC ASSOCIATED WITH FAIRLY VIGOROUS H85 THETA E ADVECTION IN ADVANCE OF AXIS OF HIER H85 DEWPTS UP TO 15C AT ABERDEEN SDAKOTA AND 13C AT INL. WHILE THE 00Z MPX/GRB RAOBS ARE QUIET DRY/STABLE WITH KINX OF 0/-2 RESPECTIVELY AND PWAT ARND 0.75 INCH /NEAR 75 PCT OF NORMAL/...THE 00Z INL RAOB IS MORE MOIST AND CONDITIONALLY UNSTABLE...WITH KINX OF 36 AND PWAT 1.47 INCH /175 PCT OF NORMAL/. DESPITE THE RATHER IMPRESSIVE MOISTENING...LATEST TRENDS INDICATE FEW IF ANY LTG STRIKES WITHIN THE CONVECTION. MAIN FCST CONCERNS IN THE SHORT TERM ARE RELATED TO PCPN CHCS ASSOCIATED WITH PAIR OF SHRTWVS NOTED ABOVE. TDAY...SHRTWVS MOVING INTO MN AND THRU ONTARIO ARE PROGGED TO CONTINUE DRIFTING E THRU THE DAY. AS AXIS OF VIGOROUS H85 THETA E ADVECTION/H85-5 QVECTOR CNVGC SHIFT E THIS MRNG...EXPECT SOME ISOLD SHRA TO INVADE THE WRN COUNTIES. BUT MODEL GUIDANCE IN GENERAL SHOWS THE SHARPER H85-5 QVECTOR CNVGC ASSOCIATED WITH THE ONTARIO SHRTWV PASSING TO THE N AND MORE VIGOROUS FORCING IN ADVANCE OF THE MN DISTURBANCE FOCUSING TO THE S BEFORE FADING IN THE AFTN. SO GOING FCST SHOWING A DIMINISHING TREND IN THE POPS THRU THE MRNG SEEMS ON TRACK. GIVEN OBSVD LTG STRIKES AND TENDENCY FOR DIMINISHING DYNAMIC SUPPORT...REMOVED MENTION OF TS THIS MRNG. WHETHER DAYTIME HEATING /DESTABILIZATION CAN REINVIGORATE/SUSTAIN ANY CONVECTION WL BE THE CONCERN FOR THE AFTN. IN FACT...THE 00Z REGIONAL GEM AND GFS ARE THE ONLY MODELS THAT GENERATE ANY PCPN OVER THE CWA THIS AFTN. THE GFS FCST SDNGS SHOW RATHER UNIMPRESSIVE LAPSE RATES WITH A TENDENCY FOR A PERSISTENT CAP AND WARMING MID LVL TEMPS IN THE 18Z-24Z TIME FRAME ASSOCIATED WITH THE FADING DYNAMIC SUPPORT. NAM/GFS MOS POPS ARE UNDER 10 AT MOST PLACES...BUT OPTED TO RETAIN SCHC POPS TO INCLUDE TS WITH ARRIVAL OF MOISTER AIR/PWAT UP TO 1.5 INCH AND SFC TEMPS EXPECTED TO REACH ARND 85 THAT WL LIFT MUCAPE UP TO 800-1000J/KG AWAY FM THE MODERATING INFLUENCE OF THE LKS. TNGT...WITH RISING HGTS/DNVA/DEEP QVECTOR DVGC...TNGT WL BE DRY AS ANY AFTN CONVECTION FIZZLES BEFORE SUNSET UNDER THE MID LVL WARMING/LOWERING SUN ANGLE. ALTHOUGH SKIES WL TURN MOCLR...STEADY SW WIND SHOULD ACT TO LIMIT THE DIURNAL TEMP FALL. THE WARMEST MIN TEMPS ARE MOST LIKELY NEAR LK SUP OVER THE W HALF...WHERE THE PRES GRADIENT WL BE A BIT TIGHER/H925 WINDS 20-25 KTS AND THIS FLOW WL DOWNSLOPE. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 359 AM EDT MON AUG 19 2013 STARTING TUE...THE CWA WILL BE BETWEEN A SFC HIGH OVER THE ATLANTIC/ERN CONUS AND AND SFC TROUGH FROM HUDSON BAY INTO THE NRN PLAINS STATES. SOME OF THE MODELS ARE HINTING AT SOME PRECIP TUE AFTERNOON...BUT ANY PRECIP SHOULD BE ISOLATED AT BEST GIVEN THAT THERE WILL NOT BE MUCH MOISTURE AVAILABLE. BEST CHANCE FOR ISOLATED SHOWERS AND THUNDERSTORMS WILL BE OVER NCENTRAL UPPER MI WHERE LAKE BREEZE CONVERGENCE WILL HELP ENCOURAGE CONVECTION ALONG. 850MB TEMPS AT 18Z TUE WILL BE RIGHT AROUND 17-18C AND WITH MOSTLY SUNNY SKIES SHOULD BE ABLE TO GET HIGH TEMPS IN THE 80S TO AROUND 90. MODELS ARE IN BETTER AGREEMENT FOR THAT TROUGH/COLD FRONT TO THE NW TO DROP ACROSS THE CWA ON WED/WED NIGHT...BUT THERE REMAINS SOME SUBTLE YET IMPORTANT UNCERTAINTY FOR THE SYSTEM. MAIN QUESTION IS WITH THE EXACT TIMING OF THE COLD FRONT...WHICH EVEN THOUGH MODELS AGREE WELL ON...THINK THAT IT WILL NOT BE CERTAIN UNTIL A LATER TIME. THE TIMING OF FROPA IS IMPORTANT BECAUSE WITH 850MB TEMPS UP TO 20C...TEMPS MAY BE COLDER THAN WHAT IS IN THE FORECAST /MAINLY OVER THE W WHERE THE FRONT MAY COME IN EARLIER THAN PREVIOUSLY INDICATED BY MODELS/. THINK THAT AREAS THAT HAVE NOT BEEN IMPACTED BY THE FRONT /AND ASSOCIATED PRECIP AND CLOUD COVER/ BY AROUND PEAK HEATING TIME WILL GET INTO THE LOW 90S /AWAY FROM LAKE MICHIGAN/. SO...IF THE COLD FRONT COMES IN AS THE MODELS ARE CURRENTLY INDICATING /INTO WRN UPPER MI BY 18Z WED AND CENTRAL UPPER MI BY 00Z THU/...PORTIONS OF WRN UPPER MI WOULD SEE HIGH TEMPS POSSIBLY 10 DEGREES COLDER THAN WHAT THE PREVIOUS FORECAST HAD. ON THE FLIP SIDE...THE FRONT COULD VERY WELL COME IN LATER THAN INDICATED BY MODELS...MEANING THE PREVIOUS FORECAST MAY BE RIGHT ON. AT THIS POINT WITH THE UNCERTAINTY...WILL NOT CHANGE TEMPS MUCH FOR WED. THE OTHER IMPACT WITH FROPA TIMING IS ON CONVECTION...SIGNIFICANT SBCAPE VALUES OF 1500-2500J/KG SHOULD BE PRESENT IN AIRMASS AHEAD OF COLD FRONT AROUND PEAK HEATING...SO WHEN THE FRONT MOVES THROUGH WILL DETERMINE STRENGTH/COVERAGE OF CONVECTION. AT THIS POINT...NOT TOO EXCITED WITH AREAL EXTENT OF CONVECTION GIVEN THAT MOISTURE WILL BE SOMEWHAT LIMITED /AT LEAST EARLY ON/. AT THE SAME TIME...THAT DRY AIR WILL HELP DCAPE VALUES GET UP TO AROUND 1000J/KG AND WITH HIGH FREEZING LEVEL AROUND 14KFT...MAIN THREAT FROM ANY STRONGER OR ISOLATED SEVERE STORMS WOULD BE STRONG WINDS. THURSDAY CERTAINLY LOOKS COOLER AND DRIER AS 850MB TEMPS AT 18Z THU WILL BE AROUND 13C WITH SFC HIGH PRESSURE MOVING IN FROM THE W. HIGH TEMPS LOOK TO BE IN THE 70S TO AROUND 80 OVER THE SCENTRAL CWA. AMPLIFIED UPPER LEVEL RIDGE WILL BE WELL TO THE W OF THE CWA. MODELS IN MUCH BETTER AGREEMENT FOR FRI WITH HAVING THE SFC HIGH EXIT TO THE E ON FRI AS THE UPPER RIDGE AXIS MOVES OVERHEAD LATE IN THE DAY. WITH SLY FLOW NOT KICKING IN AND UPPER RIDGE NOT ARRIVING UNTIL LATE IN THE DAY OR UNTIL FRI NIGHT...WILL NOT HAVE SUFFICIENT ADVECTION OF WARMER AIRMASS INTO THE AREA. HIGH TEMPS LOOK SIMILAR OR A DEGREE OR TWO COOLER THAN THURSDAY...WITH HIGHS PRIMARILY IN THE 70S /WITH SOME COOLER SPOTS NEAR LAKE SUPERIOR/. UNCERTAINTY INCREASES CONSIDERABLY FOR SAT AND SUN DUE TO MODEL DISAGREEMENT AND RUN TO RUN DISCONTINUITY. WILL JUST USE CONSENSUS OF MODELS FOR THIS PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 128 PM EDT MON AUG 19 2013 WITH RELATIVELY DRY LOW-LEVELS PERSISTING...VFR CONDITIONS ARE EXPECTED THRU THIS FCST PERIOD AT KIWD/KCMX/KSAW. A WEAK DISTURBANCE PASSING OVER THE UPPER LAKES COMBINED WITH BUILDING DAYTIME INSTABILITY COULD SPARK ISOLD CONVECTION THIS AFTN WHICH MIGHT AFFECT KIWD/KSAW. HOWEVER...CONFIDENCE IN DEVELOPMENT/LOCATION OF ANY SHRA/TSRA IS VERY LOW. SO...NO MENTION OF SHRA/TSRA WAS INCLUDED IN THIS FCST. AS WITH RECENT NIGHTS...INCREASING SW WINDS TONIGHT ABOVE NOCTURNAL INVERSION WILL APPROACH LLWS CRITERIA. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 359 AM EDT MON AUG 19 2013 OVERALL...EXPECT WINDS LESS THAN 20 KTS THRU THE PERIOD AS A RELATIVELY WEAK PRES GRADIENT TYPICAL OF SUMMER PERSISTS OVER THE GREAT LAKES REGION. THE ARRIVAL OF MORE HUMID AIR FOR TUE/WED MAY RESULT IN SOME FOG FORMATION OVER THE COOLER LAKE WATERS. HOWEVER...FOG WILL BE MUCH MORE LIKELY TO DEVELOP IF SOME SHOWERS OCCUR OVER THE LAKE. ANY FOG WILL DISSIPATE THU FOLLOWING A COLD FRONTAL PASSAGE AND THE ARRIVAL OF DRIER AIR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...TITUS AVIATION...ROLFSON MARINE...KC
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
537 PM CDT MON AUG 19 2013 UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE .SHORT TERM...TONIGHT AND TUESDAY ISSUED AT 227 PM CDT MON AUG 19 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A SHORTWAVE TROUGH MOVING EAST OVER EASTERN MINNESOTA EARLY THIS AFTERNOON. EARLIER SHOWERS AND STORMS OVER NORTHWEST WISCONSIN FIZZLED AND THINGS REMAIN QUIET DESPITE DECENT MU CAPES OF OVER 1000 J/KG. WILL LEAVE A SLIGHT CHANCE OF PRECIP FOR THE REST OF THE AFTERNOON OVER N-C WISCONSIN THOUGH. CLOUD COVER HAS HELD BACK TEMPS SOMEWHAT...AND ARE ONLY IN THE UPPER 70S ACROSS THE NORTH. LOOKING FARTHER UPSTREAM...PLENTY OF CLEAR CONDITIONS OVER THE NORTHERN PLAINS. SMALL PRECIP CHANCES AND TEMPS ARE THE MAIN FORECAST CONCERNS IN THE SHORT-TERM. TONIGHT...THE SHORTWAVE TROUGH MOVING OVER THE WESTERN GREAT LAKES WILL SHEAR APART INTO TWO FEATURES. ONE WAVE WILL CONTINUE TO MOVE EAST OVER SOUTHERN ONTARIO WHILE THE OTHER DIVES SOUTH ACROSS IOWA. AS THIS OCCURS...BAND OF MID AND HIGH LEVEL MOISTURE WILL GET STRETCHED AND DIMINISH...SO ANTICIPATE CLEARING SKIES TO OCCUR THIS EVENING. THEN THE 850MB MOISTURE PLUME OVER THE CENTRAL AND NORTHERN PLAINS EDGES EAST AND NOSES INTO WESTERN AND NORTHERN WISCONSIN LATE TONIGHT. SCT TO WIDELY SCT CLOUDS ARE OCCURRING WITHIN THIS MOISTURE PLUME AND BUFKIT SOUNDINGS AT RHI INDICATE SKINNY CAPE UPWARDS OF 1000 J/KG DEVELOPING BY 09Z. WITH MOISTURE TRANSPORT OCCURRING...CHANCES OF PRECIP ARE NOT NEGLIGIBLE...BUT PLENTY OF DRY AIR EXISTS ABOVE 850MB AND MID-LEVEL LAPSE RATES ARE RATHER POOR. WILL CONTINUE WITH THE DRY FORECAST. MUGGIER CONDITIONS WITH LOWS IN THE UPPER 50S TO LOW 60S. TUESDAY...LOW LEVEL MOISTURE PLUME WILL STRETCH FROM KANSAS TO NORTHWEST WISCONSIN...PUSHING DEWPOINTS INTO THE MIDDLE 60S. WITH TEMPS RISING INTO THE MID TO UPPER 80S...SHOULD SEE A DECENT CU FIELD DEVELOP OVER CENTRAL AND NORTH-CENTRAL WISCONSIN. DESPITE MID-LEVEL CAPPING...ML CAPES TOMORROW WILL REACH UPWARDS OF 2K J/KG WITH NO CIN. NO TRIGGER ALOFT SO WILL GO WITH THE CONSENSUS WHICH IS A DRY FORECAST. .LONG TERM...TUESDAY NIGHT THROUGH MONDAY ISSUED AT 227 PM CDT MON AUG 19 2013 FOCUS OF THIS PERIOD OF THE FORECAST WILL BE THE COLD FRONT PASSAGE WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. THIS COLD FRONT WILL BE SUPPORTED BY A SHORT WAVE TROUGH DROPPING INTO THE NORTHERN GREAT LAKES REGION ALONG WITH A RRQ REGION OF THE UPPER JET. INCREASING MOIST WARM UNSTABLE AIR MASS PRODUCING CAPES FROM 2500 TO 3000 J/KG FOR THE AFTERNOON HOURS AHEAD OF THE FRONT. GOING HWO WILL CONTINUE TO HIGHLIGHT THE SVR THREAT. HEAT INDEX NUMBERS ALSO CLIMB INTO THE LOWER 90S AHEAD OF THE FRONT ON WEDNESDAY. MEDIUM RANGE MODELS CONSISTENT WITH DRIVING THE FRONT SOUTH ON THURSDAY FOR DRIER CONDITIONS AND MORE NORMAL TEMPERATURES. PRECIPITATION TRENDS BECOME A CHALLENGE AGAIN LATER FRIDAY INTO NEXT MONDAY. RETURN FLOW FRIDAY NIGHT INTO SATURDAY MAY PRODUCE A PERIOD OF WAA CONVECTION...FOLLOWED BY PERIODS OF CONVECTION ON THE NORTHERN PERIMETER OF THE BUILDING UPPER RIDGE LATER WEEKEND INTO NEXT MONDAY. ORIENTATION OF THIS RIDGE WILL PLAY A ROLE WHERE THE BEST CHANCE OF CONVECTION OCCURS. WITH THE BUILDING RIDGE AGAIN THIS WEEKEND INTO NEXT WEEK...THE WARM AND MORE HUMID AIR MASS WILL RETURN. HEAT INDEX NUMBERS LIKELY TO CLIMB BACK INTO THE LOWER 90S EXCEPT FOR LOCATIONS ACROSS THE NORTH WHWERE CONVECTION CAN DEVELOP. && .AVIATION...FOR 00Z TAF ISSUANCE ISSUED AT 532 PM CDT MON AUG 19 2013 DECOUPLING OVERNIGHT WL ALLOW WINDS TO DIMINISH AND GUSTINESS TO END. INCREASED MOISTURE COULD RESULT IN SOME MVFR VSBYS BY MORNING IN FG/HZ. DEEPENING MIXING WL BRING BACK THE GUSTINESS TO THE WIND AGAIN TOMORROW. INCREASED MOISTURE COULD RESULT IN SOME LOWER-END VFR CIGS BY EARLY TOMORROW AFTN...ESP IN C/N-C WI. ATM WL DESTABILIZE SOME AND THERE DOESN/T APPEAR TO BE ANY CINH REMAINING IN FCST SOUDNINGS. BUT GIVEN THE LACK OF A TRIGGER...EXPECT CONVECTION TO BE ISOLD AT BEST AND THUS RISK OF GETTING TSRA AT TAF SITES NOT GREAT ENOUGH TO WARRANT INCLUSION IN TAFS AT THIS POINT. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......SKOWRONSKI
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
249 PM CDT MON AUG 19 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 249 PM CDT MON AUG 19 2013 MAIN FORECAST CONCERNS ARE ON ANY POTENTIAL PRECIPITATION TONIGHT AND THEN TEMPERATURES FOR TUESDAY. CURRENTLY AS OF 19Z... WATER VAPOR LOOP AND RAP 500MB HEIGHT ANALYSIS SHOWED TROUGHING ALONG THE WEST COAST OF BRITISH COLUMBIA...UPPER RIDGING FROM THE SOUTHWESTERN U.S. INTO THE DAKOTAS...AND A SHORTWAVE TROUGH OVER CENTRAL MN. THE MAIN IMPACT TO THE FORECAST AREA WITH THE SHORTWAVE TROUGH HAS BEEN TO SPREAD SOME MID AND HIGH CLOUDS ACROSS. DRY AIR IN THE MID LEVELS OF THE ATMOSPHERE SEEN ON THE 12Z MPX SOUNDING... AS WELL AS A CAPPING INVERSION AT 750MB ON THAT SOUNDING...HAS PREVENTED THE SHORTWAVE FROM PRODUCING PRECIPITATION IN THE FORECAST AREA. THE CLOUD COVER HAS ALSO HELD BACK TEMPERATURES FROM REACHING THEIR MAXIMUM POTENTIAL. 16C 850MB TEMP ON THE MPX SOUNDING WAS ADVECTING EAST INTO THE FORECAST AREA...WHICH NORMALLY WOULD SUPPORT MID TO EVEN UPPER 80S WITH CLEAR SKIES. HOWEVER...THE CLOUDS HAVE HELD TEMPS DOWN INTO THE UPPER 70S TO LOW 80S THUS FAR. LOW LEVEL SOUTHERLY FLOW HAS SLOWLY BEEN BRINGING IN MORE MOISTURE WITH DEWPOINTS IN THE UPPER 50S TO LOW 60S. TO THE NORTHWEST...A COLD FRONT STRETCHED FROM CENTRAL MANITOBA INTO WESTERN MONTANA. AHEAD OF THE FRONT...12Z RAOBS SHOWED EVEN WARMER AIR ACROSS THE NORTHERN PLAINS...WITH 850MB READINGS OF 20-25C AT BIS...ABR...UNR AND GGW. 700MB TEMPS WERE WARMING AS WELL...BETWEEN 8-13C. SYNOPTIC OVERVIEW... THE SHORTWAVE TROUGH OVER CENTRAL MN IS PROGGED TO DROP SOUTH THROUGH THE FORECAST AREA THIS EVENING...WITH THE EXTENSION OF THE UPPER RIDGE OVER THE DAKOTAS FOLLOWING IN BEHIND IT FOR THE OVERNIGHT HOURS INTO TUESDAY. DETAILS... GIVEN THE DRY AIRMASS IN PLACE SUB THE MID-CLOUD LAYER AS WELL AS THE CAPPING...NOT ANTICIPATING ANY PRECIPITATION TO ACCOMPANY THE SHORTWAVE AS IT DROPS THROUGH THE FORECAST AREA THIS EVENING. WE SHOULD SEE SOME CLEARING AS WELL...BOTH OF THE MID/HIGH CLOUDS AND DIURNAL CUMULUS...AS SUBSIDENCE WORKS IN BEHIND THE SHORTWAVE TROUGH. 850MB MOISTURE TRANSPORT THEN KICKS IN...TRANSPORTING MORE LOW LEVEL MOISTURE INTO THE AREA. THE 19.12Z NAM/REGIONAL CANADIAN BOTH DEVELOP A FEW ACCAS TYPE SHOWERS AND THUNDERSTORMS ON THE EDGE OF THIS MOISTURE TRANSPORT FROM SOUTHEAST MN INTO NORTHWEST WI. THESE ARE REALLY THE ONLY MODELS SHOWING THIS...AND WITH A BROAD 850MB MOISTURE TRANSPORT PLUME PROGGED COMBINED WITH SUBSIDENCE... THINK THEY ARE OVERDONE AND KEPT A DRY FORECAST GOING. WORTH KEEPING AN EYE ON...THOUGH. THE MORE MOISTURE COMING IN COMBINED WITH DAYTIME HEATING SHOULD YIELD TO PLENTY OF CUMULUS ON TUESDAY. LITTLE IN THE WAY OF CAPPING IS PROGGED TOMORROW WITH MLCIN VALUES DROPPING TO 30-40 J/KG IN THE AFTERNOON...WHILE MLCAPES GROW TO 1500-2500 J/KG. HOWEVER...THERE IS NO TRIGGER PRESENT TO ALLOW THE RELEASE OF THE INSTABILITY. THEREFORE...DRY CONDITIONS ARE FORECAST THROUGH TUESDAY. TEMPERATURES TONIGHT EXPECTED TO BE WARMER...ESPECIALLY OVER THE NORTHWEST HALF OF THE FORECAST AREA...DUE TO A SOUTHERLY BREEZE AND HIGHER DEWPOINTS. THE SOUTHERLY BREEZE SHOULD PRECLUDE VALLEY FOG PRETTY MUCH EVERYWHERE EXCEPT FOR THE WISCONSIN RIVER VALLEY. 850MB AND 925MB TEMPS ARE PROGGED ABOUT 2-3C HIGHER ON TUESDAY AFTERNOON COMPARED TO THIS AFTERNOON. THESE WARMER TEMPS COMBINED WITH MORE SUN WILL LEAD TO WARMER CONDITIONS...LIKELY BY 5 OR SO DEGREES. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 249 PM CDT MON AUG 19 2013 HAZARDS... HEAT INDICES MAY GET CLOSE TO ADVISORY CRITERIA ON WEDNESDAY AND AGAIN SUNDAY AND MONDAY. ALSO MONITORING POTENTIAL SEVERE WEATHER FOR LATE WEDNESDAY. SYNOPTIC OVERVIEW... TROUGHING ALONG THE WEST COAST OF BRITISH COLUMBIA IS FORECAST CONCERN NUMBER 1...WITH MODELS STRUGGLING A BIT ON THE AMPLITUDE OF THE TROUGH AS IT CROSSES SOUTHERN CANADA THE NEXT COUPLE OF DAYS. SOME PAST GFS RUNS INDICATED THE TROUGH COULD DIP INTO NORTHERN MINNESOTA LATE WEDNESDAY...WHEREAS THE ECMWF AS WELL AS THE 19.12Z GFS KEEP IT TO THE NORTH CROSSING NORTHERN ONTARIO. THIS IS IMPORTANT AS IT IMPACTS HOW FAR SOUTH DYNAMICAL FORCING WILL REACH INTO THE FORECAST AREA. ADDITIONALLY...THIS SHORTWAVE TROUGH IS GOING TO DICTATE THE SPEED OF THE COLD FRONT OVER MONTANA...THE FORCING ON THE FRONT...AND HOW FAR SOUTH THE FRONT GETS HEADING INTO THURSDAY AND THURSDAY NIGHT. GOOD MODEL AGREEMENT PERSISTS HEADING INTO NEXT WEEKEND AS THE SUMMER HEAT RIDGE BUILDS AND STRENGTHENS OVER THE NATIONS HEARTLAND. VERY LITTLE MOVEMENT OF THIS RIDGE IS SUGGESTED BY MONDAY. TUESDAY NIGHT THROUGH THURSDAY... FOCUS IS ON THE COLD FRONT APPROACHING THE AREA. ALL MODELS ARE SHOWING AN ELEVATED MIX LAYER...I.E. THE WARMER 850MB AND 700MB AIR PRESENT CURRENTLY OVER THE NORTHERN PLAINS...ADVECTING INTO THE FORECAST AREA TUESDAY NIGHT AND WEDNESDAY AHEAD OF THE FRONT. THE EXACT WARMTH IS ONE FACTOR THAT WILL PLAY INTO WHETHER OR NOT THIS FRONT CAN INITIATE CONVECTION WEDNESDAY AFTERNOON. ANOTHER FACTOR IS MOISTURE...WHICH THE 19.12Z GFS AND NAM BOTH APPEAR TO BE OVERDOING THE SURFACE DEWPOINTS. THEY PROG VALUES IN THE 70-75 RANGE WHILE MIXING AND THE DRYING SOILS SHOULD RESULT IN READINGS MORE IN THE MID/UPPER 60S. THESE MIXED LAYER DEWPOINTS RESULT IN MLCIN VALUES OF 30-50 J/KG. A THIRD FACTOR OF CONCERN IS LOW LEVEL CONVERGENCE... WHICH THE NAM AND GFS BOTH PROG WEAK TO NOTHING PRIOR TO THEIR CONVECTIVE SCHEMES GOING OFF. THUS...THERE IS PLENTY OF UNCERTAINTY ON THE EXTENT OF POTENTIAL CONVECTION. IN REALITY...THERE IS A BETTER SHOT FOR CONVECTION ONCE THE FRONT PASSES...DUE TO THE DEVELOPMENT OF A POST-FRONTAL LOW TO MID LEVEL FRONTOGENESIS ZONE. HAVE TAILORED PRECIPITATION CHANCES IN THIS WAY WITH HIGHER VALUES WEDNESDAY NIGHT. PRECIPITATION CHANCES CONTINUE INTO THURSDAY... MAINLY SOUTH OF I-90...WHERE THE FRONTOGENESIS ZONE MAY STILL BE LINGERING. THIS IS ALL DEPENDS ON HOW FAR SOUTH THE FRONT MAKES IT...THOUGH. FOR SEVERE WEATHER POTENTIAL...THE 0-6KM SHEAR IS SERIOUSLY LAGGING THE FRONT. 25 KT IS ABOUT THE HIGHEST AT 00Z AND THATS UP NEAR EAU CLAIRE. 0-3 KM IS NOT MUCH BETTER WITH SIMILAR VALUES. THUS THINKING THAT IF THERE IS A SEVERE RISK...MORE LIKELY IT IS UP NORTH OF HWY 10 DURING THE LATE AFTERNOON/EVENING HOURS. ON THE TEMPERATURE SIDE OF THINGS...925MB READINGS FROM THE ECMWF/GFS ARE PROGGED TO CLIMB TO 24-26C LATE WEDNESDAY. WITH PLENTY OF SUN MUCH OF THE DAY AND A SOUTHWEST BREEZE...HIGHS SHOULD TOP OUT BETWEEN THE UPPER 80S AND MID 90S. DEWPOINTS MIXING DOWN INTO THE MID TO UPPER 60S WILL HELP TO HOLD HEAT INDICES BELOW ADVISORY CRITERIA. 925MB TEMPS COOLING TO 20-22C FOR THURSDAY LIKELY TO DROP TEMPS 5-10 DEGREES FROM WEDNESDAY. THURSDAY NIGHT THROUGH MONDAY... INITIAL FOCUS FOR THIS TIME PERIOD IS THE RETURN BACK NORTH OF THE COLD FRONT...I.E. SWITCHING TO A WARM FRONT...AND IF ANY CONVECTION CAN FIRE ON THAT. THE 19.00Z ECMWF IS THE MOST BULLISH ON FIRING CONVECTION FOR THURSDAY NIGHT AND FRIDAY AS THE FRONT LIFTS THROUGH THE FORECAST AREA. 19.12Z GFS/CANADIAN ARE BOTH DRY. NEXT CONCERN TURNS TO THE HEAT FOR THE WEEKEND INTO MONDAY AS THE STRONG SUBTROPICAL RIDGE FORMS OVER NEBRASKA...IOWA...KANSAS AND MISSOURI. THE BULK OF THE HEAT WITH 850MB TEMPS OF 24C OR HIGHER LOOKS TO STAY WELL OFF TO THE WEST OVER THE DAKOTAS INTO WESTERN PORTIONS OF NEBRASKA AND KANSAS. HOWEVER...THEY SHOULD STILL TOP OUT IN THE 18-22C RANGE FOR SATURDAY THROUGH MONDAY...WITH THE HIGHER READINGS OF 20-22C LIKELY OCCURRING SUNDAY AND MONDAY. THESE ARE 1.5-2 STANDARD DEVIATIONS ABOVE NORMAL...WHICH WOULD IMPLY CLOSE TO BUT NOT REACHING OR EXCEEDING RECORD HIGHS. LOW TEMPERATURES COULD TURN OUT QUITE WARM AS WELL WITH A PERSISTENT SOUTH TO SOUTHWEST BREEZE. INDICATIONS FROM THE 19.12Z ECMWF THAT THE WELL ABOVE NORMAL TEMPERATURES COULD STICK AROUND WELL BEYOND MONDAY. PRECIPITATION CHANCES FOR THE WEEKEND INTO EARLY NEXT WEEK SHOULD STAY CONFINED MOSTLY NORTH OF THE FORECAST AREA...WHERE THE WARM FRONT FROM THURSDAY NIGHT/FRIDAY WILL BE LOCATED. THERE ARE POSSIBILITIES THAT THE FRONT COULD SLIP BACK SOUTH INTO NORTHERN SECTIONS OF THE FORECAST AREA AT TIMES SUNDAY NIGHT AND MONDAY...THUS HAVE SOME CHANCES IN FOR THIS PERIOD. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1220 PM CDT MON AUG 19 2013 SHORT WAVE TROUGH MOVING SLOWLY ACROSS THE UPPER MIDWEST TODAY CONTINUES TO PRODUCE A HIGH VFR CEILINGS OVER BOTH TAF SITES. RADAR SUGGESTS SOME SPRINKLES FROM TIME TO TIME ARE POSSIBLE...BUT THIS HAS BEEN TO THE NORTH. CANNOT TOTALLY RULE THESE OUT THROUGH THE REMAINDER OF THE AFTERNOON AS BOTH THE 19.12Z NAM AND 19.15Z RAP SHOW AN INCREASE IN THE LOW LEVEL MOISTURE TRANSPORT. DESPITE THIS EXPECTED INCREASE IN THE MOISTURE TRANSPORT...FORECAST SOUNDINGS CONTINUE TO SHOW QUITE A BIT OF DRY AIR IN THE LOW LEVELS SO WOULD NOT EXPECT ANYTHING MORE THAN SPRINKLES. ONCE THIS WAVE MOVES PAST...SKIES SHOULD CLEAR OUT THIS EVENING AND REMAIN THAT WAY INTO TUESDAY MORNING. WITH HIGH PRESSURE REMAINING OVER THE OHIO RIVER VALLEY AND A COLD FRONT SLOWLY APPROACHING FROM THE NORTHWEST...ENOUGH OF A GRADIENT TO KEEP THE WINDS UP OVERNIGHT WHICH SHOULD PRECLUDE THE FORMATION OF ANY VALLEY FOG. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...04
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND TUESDAY ISSUED AT 227 PM CDT MON AUG 19 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A SHORTWAVE TROUGH MOVING EAST OVER EASTERN MINNESOTA EARLY THIS AFTERNOON. EARLIER SHOWERS AND STORMS OVER NORTHWEST WISCONSIN FIZZLED AND THINGS REMAIN QUIET DESPITE DECENT MU CAPES OF OVER 1000 J/KG. WILL LEAVE A SLIGHT CHANCE OF PRECIP FOR THE REST OF THE AFTERNOON OVER N-C WISCONSIN THOUGH. CLOUD COVER HAS HELD BACK TEMPS SOMEWHAT...AND ARE ONLY IN THE UPPER 70S ACROSS THE NORTH. LOOKING FARTHER UPSTREAM...PLENTY OF CLEAR CONDITIONS OVER THE NORTHERN PLAINS. SMALL PRECIP CHANCES AND TEMPS ARE THE MAIN FORECAST CONCERNS IN THE SHORT-TERM. TONIGHT...THE SHORTWAVE TROUGH MOVING OVER THE WESTERN GREAT LAKES WILL SHEAR APART INTO TWO FEATURES. ONE WAVE WILL CONTINUE TO MOVE EAST OVER SOUTHERN ONTARIO WHILE THE OTHER DIVES SOUTH ACROSS IOWA. AS THIS OCCURS...BAND OF MID AND HIGH LEVEL MOISTURE WILL GET STRETCHED AND DIMINISH...SO ANTICIPATE CLEARING SKIES TO OCCUR THIS EVENING. THEN THE 850MB MOISTURE PLUME OVER THE CENTRAL AND NORTHERN PLAINS EDGES EAST AND NOSES INTO WESTERN AND NORTHERN WISCONSIN LATE TONIGHT. SCT TO WIDELY SCT CLOUDS ARE OCCURRING WITHIN THIS MOISTURE PLUME AND BUFKIT SOUNDINGS AT RHI INDICATE SKINNY CAPE UPWARDS OF 1000 J/KG DEVELOPING BY 09Z. WITH MOISTURE TRANSPORT OCCURRING...CHANCES OF PRECIP ARE NOT NEGLIGIBLE...BUT PLENTY OF DRY AIR EXISTS ABOVE 850MB AND MID-LEVEL LAPSE RATES ARE RATHER POOR. WILL CONTINUE WITH THE DRY FORECAST. MUGGIER CONDITIONS WITH LOWS IN THE UPPER 50S TO LOW 60S. TUESDAY...LOW LEVEL MOISTURE PLUME WILL STRETCH FROM KANSAS TO NORTHWEST WISCONSIN...PUSHING DEWPOINTS INTO THE MIDDLE 60S. WITH TEMPS RISING INTO THE MID TO UPPER 80S...SHOULD SEE A DECENT CU FIELD DEVELOP OVER CENTRAL AND NORTH-CENTRAL WISCONSIN. DESPITE MID-LEVEL CAPPING...ML CAPES TOMORROW WILL REACH UPWARDS OF 2K J/KG WITH NO CIN. NO TRIGGER ALOFT SO WILL GO WITH THE CONSENSUS WHICH IS A DRY FORECAST. .LONG TERM...TUESDAY NIGHT THROUGH MONDAY ISSUED AT 227 PM CDT MON AUG 19 2013 FOCUS OF THIS PERIOD OF THE FORECAST WILL BE THE COLD FRONT PASSAGE WEDNESDAY AFTERNOON INTO WEDNESDAY NIGHT. THIS COLD FRONT WILL BE SUPPORTED BY A SHORT WAVE TROUGH DROPPING INTO THE NORTHERN GREAT LAKES REGION ALONG WITH A RRQ REGION OF THE UPPER JET. INCREASING MOIST WARM UNSTABLE AIR MASS PRODUCING CAPES FROM 2500 TO 3000 J/KG FOR THE AFTERNOON HOURS AHEAD OF THE FRONT. GOING HWO WILL CONTINUE TO HIGHLIGHT THE SVR THREAT. HEAT INDEX NUMBERS ALSO CLIMB INTO THE LOWER 90S AHEAD OF THE FRONT ON WEDNESDAY. MEDIUM RANGE MODELS CONSISTENT WITH DRIVING THE FRONT SOUTH ON THURSDAY FOR DRIER CONDITIONS AND MORE NORMAL TEMPERATURES. PRECIPITATION TRENDS BECOME A CHALLENGE AGAIN LATER FRIDAY INTO NEXT MONDAY. RETURN FLOW FRIDAY NIGHT INTO SATURDAY MAY PRODUCE A PERIOD OF WAA CONVECTION...FOLLOWED BY PERIODS OF CONVECTION ON THE NORTHERN PERIMETER OF THE BUILDING UPPER RIDGE LATER WEEKEND INTO NEXT MONDAY. ORIENTATION OF THIS RIDGE WILL PLAY A ROLE WHERE THE BEST CHANCE OF CONVECTION OCCURS. WITH THE BUILDING RIDGE AGAIN THIS WEEKEND INTO NEXT WEEK...THE WARM AND MORE HUMID AIR MASS WILL RETURN. HEAT INDEX NUMBERS LIKELY TO CLIMB BACK INTO THE LOWER 90S EXCEPT FOR LOCATIONS ACROSS THE NORTH WHWERE CONVECTION CAN DEVELOP. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1202 PM CDT MON AUG 19 2013 MAINLY VFR CONDITIONS ACROSS THE REGION THROUGH THE TAF PERIOD. WIDELY SCT SHOWERS AND THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON OVER NORTH-CENTRAL WISCONSIN. COVERAGE IS EXPECTED TO BE LOW ENOUGH TO LEAVE OUT OF TAFS. PATCHY MVFR VSBYS IN MIST IS POSSIBLE LATE TONIGHT. MOISTURE INCREASES FROM THE SOUTHERN PLAINS TOMORROW...WHICH SHOULD LEAD TO BUILDING CLOUDS OVER THE COURSE OF THE MORNING...MAINLY FOR CENTRAL AND NORTH-CENTRAL WISCONSIN. && .GRB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM.....MPC LONG TERM......TDH AVIATION.......MPC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1220 PM CDT MON AUG 19 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 327 AM CDT MON AUG 19 2013 THE MAIN FOCUS FOR TODAY IS ON A MID LEVEL TROUGH THAT WILL COME THROUGH AND WHETHER IT WILL HAVE ENOUGH LIFT TO OVERCOME THE DRY LOW LEVEL AIR AND PRODUCE SOME RAIN SHOWERS. THIS MID LEVEL TROUGH IS CURRENTLY ANALYZED VIA WATER VAPOR IR AND 19.06Z RAP 500MB ANALYSIS FROM SOUTHWESTERN ONTARIO THROUGH MINNESOTA AND EASTERN NEBRASKA. SOME VERY HIGH BASED RADAR RETURNS HAVE BEEN SHOWING UP ACROSS EASTERN SOUTH DAKOTA AND WESTERN MINNESOTA THOUGH THERE HAVE NOT BEEN MANY SIGHTS REPORTING THAT THE RAIN IS REACHING THE GROUND. THIS IS ALSO IN A BELT OF HIGHER LOW LEVEL MOISTURE TRANSPORT THAT IS TRAPPED UNDER A 700MB INVERSION...BUT IS HELPING TO RAISE SURFACE DEW POINTS. THIS IN TURN HAS CREATED A MORE UNSTABLE AIR MASS FROM THE DAKOTAS UP INTO NORTHERN MINNESOTA. THE 19.07Z RAP KEEPS MUCH OF THIS MOISTURE TRANSPORT AND HIGHER INSTABILITY OUT TO THE WEST TODAY...SO THIS TROUGH WILL BE ENTERING AN ENVIRONMENT THAT IS LESS FAVORABLE TO SEE THE SHOWERS CONTINUE. CONSIDERED PUTTING IN A MENTION OF SPRINKLES TODAY IN FOR SOUTHEAST MINNESOTA AND WESTERN TO NORTH CENTRAL WISCONSIN...BUT HELD OFF FOR THE TIME BEING SINCE REFLECTIVITIES OUT WEST APPEAR TO BE ON A WEAKENING TREND. MID TO HIGH LEVEL CLOUD COVER WILL BE FAIRLY WIDESPREAD FOR A PORTION OF THE DAY WHICH WILL KEEP TEMPERATURES DOWN A LITTLE BIT. THE 19.00Z NAM/GFS SHOW SOME WARMER 850/925MB AIR MOVING IN THIS AFTERNOON AS SOME OF THIS CLOUD COVER EXITS. EXPECT THAT WE WILL WARM UP PRETTY QUICKLY AS THIS OCCURS...BUT PERHAPS NOT AS HIGH AS PREVIOUSLY ADVERTISED. .LONG TERM...(TUESDAY THROUGH SUNDAY) ISSUED AT 327 AM CDT MON AUG 19 2013 CONDITIONS WILL CONTINUE TO WARM INTO MID WEEK AHEAD OF A COLD FRONT/TROUGH THAT WILL PROPAGATE INTO THE REGION ON WEDNESDAY. WEDNESDAY IS EXPECTED TO BE THE WARMEST DAY OF THE WEEK WITH LOW LEVEL WARM AIR ADVECTION BUMPING 925MB TEMPERATURES UP TO AROUND 26C AND 850MB TEMPERATURES TO 20C. THIS WARM LAYER SHOULD ALSO HELP TO KEEP THE WARM SECTOR CAPPED OFF UNTIL THE COLD FRONT DROPS DOWN LATE WEDNESDAY AFTERNOON AND EVENING. THE AIR MASS WILL BECOME UNSTABLE WITH MODIFIED 19.00Z NAM/GFS SOUNDINGS...MODIFIED FOR LOWER DEW POINTS IN THE MID/UPPER 60S...SHOWING BETWEEN 1500-2500 J/KG OF 0-3KM MUCAPE ALONG A NARROW CORRIDOR JUST AHEAD OF THE FRONT. WIND SHEAR LOOKS MARGINAL WITH THE BETTER DEEP SHEAR IN CENTRAL MINNESOTA/NORTHERN WISCONSIN WHERE 500MB WINDS WILL BE AROUND 40KTS DUE TO THE MID LEVEL SHORT WAVE TROUGH DROPPING INTO THE NORTHERN GREAT LAKES. FURTHER SOUTHWEST ALONG THE FRONT CLOSER TO SOUTHERN MINNESOTA AND NORTHERN IOWA...19.00Z NAM/GFS SOUNDINGS/HODOGRAPHS DO SHOW SOME DIRECTIONAL/SPEED SHEAR IN THE LOWEST 2KM WHICH WOULD BE MORE FAVORABLE FOR STRONGER WINDS. BASED ON THE INSTABILITY AND SHEAR...IT APPEARS THAT LARGE HAIL AND DAMAGING WINDS STILL APPEAR TO BE THE MAIN THREATS IN THE LATE AFTERNOON INTO THE EVENING...PARTICULARLY ACROSS SOUTHEAST MINNESOTA...WESTERN WISCONSIN AND NORTHEAST IOWA. THE ISSUE THEN CONTINUES TO BE WITH HOW FAR SOUTH WILL THE COLD FRONT MAKE IT AND THEN HOW FAST DOES IT GET PUSHED BACK TO THE NORTH AS A WARM FRONT BY THE END OF THE WEEK. THE ECMWF HAS TRENDED TOWARD WHAT THE GFS/GEM HAVE BEEN ADVERTISING THE PAST FEW DAYS WITH HAVING THE FRONT DROP SOUTH INTO IOWA/NORTHERN ILLINOIS BY THURSDAY MORNING...BUT THE 19.00Z ECMWF STILL REMAINS THE FURTHEST NORTH WITH WHERE IT STALLS OUT. THERE ALSO IS BETTER CONTINUITY WITH THE NEXT TROUGH TRACKING ACROSS THE NORTHERN PLAINS ON FRIDAY INTO SATURDAY WHICH IS WHEN THE FRONT COMES BACK NORTH AS A WARM FRONT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z TUESDAY AFTERNOON) ISSUED AT 1220 PM CDT MON AUG 19 2013 SHORT WAVE TROUGH MOVING SLOWLY ACROSS THE UPPER MIDWEST TODAY CONTINUES TO PRODUCE A HIGH VFR CEILINGS OVER BOTH TAF SITES. RADAR SUGGESTS SOME SPRINKLES FROM TIME TO TIME ARE POSSIBLE...BUT THIS HAS BEEN TO THE NORTH. CANNOT TOTALLY RULE THESE OUT THROUGH THE REMAINDER OF THE AFTERNOON AS BOTH THE 19.12Z NAM AND 19.15Z RAP SHOW AN INCREASE IN THE LOW LEVEL MOISTURE TRANSPORT. DESPITE THIS EXPECTED INCREASE IN THE MOISTURE TRANSPORT...FORECAST SOUNDINGS CONTINUE TO SHOW QUITE A BIT OF DRY AIR IN THE LOW LEVELS SO WOULD NOT EXPECT ANYTHING MORE THAN SPRINKLES. ONCE THIS WAVE MOVES PAST...SKIES SHOULD CLEAR OUT THIS EVENING AND REMAIN THAT WAY INTO TUESDAY MORNING. WITH HIGH PRESSURE REMAINING OVER THE OHIO RIVER VALLEY AND A COLD FRONT SLOWLY APPROACHING FROM THE NORTHWEST...ENOUGH OF A GRADIENT TO KEEP THE WINDS UP OVERNIGHT WHICH SHOULD PRECLUDE THE FORMATION OF ANY VALLEY FOG. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...HALBACH LONG TERM...HALBACH AVIATION...04