Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 081340 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 940 AM EDT TUE JUL 8 2014 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE WEST TODAY AND WILL GRADUALLY STALL ALONG THE COAST ON WEDNESDAY. THE FRONT WILL SLOWLY PUSH OFF TO THE EAST WEDNESDAY NIGHT AND THURSDAY AS HIGH PRESSURE BUILDS IN FROM THE WEST. HIGH PRESSURE WILL CREST OVER THE REGION THURSDAY NIGHT AND WILL HOLD OVER THE AREA ON FRIDAY. HIGH PRESSURE WILL SHIFT OFFSHORE ON SATURDAY AND WILL DRIFT OFF TO THE EAST ON SUNDAY AS A WARM FRONT APPROACHES FROM THE SOUTHWEST. THE WARM FRONT WILL LIFT INTO THE REGION SUNDAY NIGHT AND WILL BE FOLLOWED BY A COLD FRONT MONDAY AFTERNOON. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE...LOADED CURRENT OBSERVATIONS AND TWEAKED SKY COVER. WILL ALLOW THE SMALL CRAFT ADVISORY FOR SEAS TO EXPIRE AT 10 AM. SEAS ARE MOSTLY IN THE 2 TO 4 FOOT RANGE NOW. EXPECT SEAS WILL COME UP AGAIN TONIGHT BASED ON GUIDANCE PRODUCTS. PREVIOUSLY... A SHORT WAVE TROUGH WILL PASS ACROSS THE CWA EARLY THIS MORNING. A FEW THUNDERSTORMS HAVE DEVELOPED ON THE LEADING EDGE OF THIS SHORT WAVE ACROSS UPSTATE NY AND VT. THERE MAY BE ENOUGH UPPER SUPPORT TO ALLOW FOR A COUPLE OF THESE SHOWERS AND STORMS TO MOVE INTO NH THROUGH ABOUT 11Z. THEREAFTER...CLOUDS SHOULD DECREASE AND ALLOW FOR AMPLE SOLAR HEATING. STRONG HEATING THIS MORNING AND AFTERNOON WILL ALLOW TEMPERATURES TO RISE WELL INTO THE 80S AT MOST LOCATIONS...WITH A FEW LOCATIONS TOUCHING 90 DEGREES. THIS COMBINED WITH DEWPOINTS IN THE 60S WILL ALLOW FOR THE DEVELOPMENT OF MODERATE SURFACE BASED CAPE BY EARLY AFTERNOON AMIDST 30-40 KT OF DEEP LAYER SHEAR. A TRIGGERING MECHANISM FOR THUNDERSTORMS IS A BIT HARD TO FIND AMIDST RISING HEIGHTS TODAY. HOWEVER...STRONG SFC/DIFFERENTIAL HEATING AND/OR SUBTLE SFC BOUNDARIES SHOULD BE SUFFICIENT FOR THE DEVELOPMENT OF WIDELY SCT SHOWERS AND THUNDERSTORMS IN THE EARLY/MID AFTERNOON HOURS. THERE MAY EVEN BE A WEAK/SUBTLE SHORT WAVE TROUGH IN OHIO THIS MORNING THAT MAY MOVE NORTHEASTWARD AND REACH OUR CWA BY MID AFTERNOON. THIS WOULD ALSO HELP TO INITIATE WIDELY SCT STORMS. AS THE LARGER PARENT SHORT WAVE TROUGH OVER THE UPPER GREAT LAKES MOVES EAST LATE TODAY...IT SHOULD INDUCE HEIGHT FALLS TOWARD EVENING AND POSSIBLY ALLOW FOR MORE WIDESPREAD THUNDERSTORM ACTIVITY...ESPECIALLY ACROSS WESTERN ZONES LATE THIS AFTERNOON. GIVEN CONVECTION INITIATION...THE COMBINATION OF OF MODERATE INSTABILITY AND SHEAR SHOULD ALLOW FOR ORGANIZATION OF THUNDERSTORMS...THEREFORE RESULTING IN A SEVERE RISK WITH THE MAIN THREAT BEING DAMAGING WINDS. HAVE ADDED GUSTY THUNDERSTORM WORDING TO THE FORECAST. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... THE GREAT LAKES SHORT WAVE TROUGH AND ATTENDANT SFC COLD FRONT WILL MOVE EASTWARD INTO NEW ENGLAND TONIGHT. WHILE THE DIURNAL COOLING CYCLE SHOULD ALLOW FOR A DECREASE IN COVERAGE OF STORMS TONIGHT...THE APPROACH OF A SHORT WAVE TROUGH...THE APPROACH OF THE RIGHT ENTRANCE REGION OF A 100 KT UPPER LEVEL JET...AND THE LOW LEVEL FORCING WITH THE SFC COLD FRONT SHOULD ALLOW FOR SCT THUNDERSTORMS MUCH OF THE NIGHT. A FEW COULD BE STRONG. ON WEDNESDAY...THE SFC COLD FRONT LOOKS TO HANG UP ACROSS OUR AREA. THIS MAY ALLOW FOR RENEWED THUNDERSTORM DEVELOPMENT BY WED AFTERNOON...A FEW OF WHICH COULD BE STRONG GIVEN STRONG SFC HEATING AND 50 KT OF DEEP LAYER SHEAR. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... COLD FRONT WILL LINGER OFF THE COAST WEDNESDAY NIGHT AND WILL GRADUALLY DRIFT OFF TO THE EAST ON THURSDAY AS HIGH PRESSURE BUILDS IN FROM THE WEST. EXPECT ANY LINGERING CONVECTION TO QUICKLY DIE OUT IN COASTAL ZONES WEDNESDAY EVENING AS DRIER AIR SHIFTS INTO THE REGION BEHIND THE FRONT. CLEARING SKIES AND LIGHT WINDS WILL ALLOW TEMPS TO DROP INTO THE MID TO UPPER 50S NORTH AND LOWER TO MID 60S SOUTH. BOTH THURSDAY AND FRIDAY WILL FEATURE STELLAR SUMMER WEATHER WITH TEMPS RANGING THROUGH THE 70S TO NEAR 80...PLENTY OF SUN AND LOW HUMIDITY. NIGHTS WILL BE VERY COMFORTABLE WITH LOWS RANGING THROUGH THE 50S TO NEAR 60. HIGH PRESSURE WILL SLIDE OFFSHORE FRIDAY NIGHT AND RETURN FLOW WILL BEGIN TO PUMP WARMER AIR BACK INTO THE REGION ON SATURDAY. WILL BE ANOTHER DAY OF SUNNY WEATHER WITH HIGHS EDGING BACK INTO THE 80S AWAY FROM THE COAST. WARMER AIR AND HIGHER DEW POINTS WILL CONTINUE TO STREAM INTO THE REGION ON SUNDAY AS A WARM FRONT APPROACHES FROM THE SOUTHWEST. WILL SEE A CHANCE OF SHOWERS AND THUNDERSTORMS IN THE AFTERNOON AS INSTABILITY BUILDS WITH DAYTIME HEATING. BEST CHANCE OF CONVECTION WILL BE IN NORTHERN ZONES ALONG AXIS OF BEST MOISTURE. COLD FRONT WILL APPROACH FROM THE WEST SUNDAY NIGHT WITH SHOWERS AND THUNDERSTORMS LIKELY LASTING INTO MONDAY AS THE FRONT GRADUALLY PUSHES INTO THE REGION FROM THE WEST. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... SHORT TERM...SOME IFR THIS MORNING IN FOG AND HAZE BUT A VFR DAY IS EXPECTED TODAY. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON WITH THEIR ATTENDANT LOCALLY THREAT FOR IFR CONDITIONS. THIS MAY CONTINUE TONIGHT WITH THE ADDITION OF PATCHY FOG AND STRATUS. VFR CONDITIONS ARE EXPECTED WEDNESDAY...BUT ADDITIONAL SHOWERS AND THUNDERSTORMS ARE EXPECTED DURING THE AFTERNOON. LONG TERM...VFR WEDNESDAY NIGHT THROUGH SATURDAY. && .MARINE... SHORT TERM...SCA FOR SEAS IN EFFECT UNTIL 10 AM THIS MORNING. A RESURGENCE OF 5-6 FT SEAS MAY OCCUR THIS EVENING AND TONIGHT AHEAD OF A COLD FRONT SO ANOTHER SCA MAY HAVE TO BE ISSUED. LONG TERM...NO PROBLEMS EXPECTED. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM EDT THIS MORNING FOR ANZ150-152. && $$ TFH

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