Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 071328 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 928 AM EDT MON JUL 7 2014 .SYNOPSIS... A WEAK WARM FRONT WILL APPROACH FROM THE WEST TODAY AND WILL GRADUALLY CROSS THE REGION TONIGHT. A COLD FRONT WILL APPROACH FROM THE WEST ON TUESDAY AND WILL CROSS THE REGION EARLY WEDNESDAY. A SECONDARY COLD FRONT WILL CROSS THE REGION WEDNESDAY NIGHT AND EARLY THURSDAY. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT ON THURSDAY NIGHT THROUGH FRIDAY. HIGH PRESSURE WILL SHIFT OFFSHORE ON SATURDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATE...HAVE MADE SOME MINOR ADJUSTMENTS BASED ON CURRENT OBSERVATIONS. WARMER AND MORE HUMID AIR WILL MOVE INTO THE FORECAST AREA TODAY. SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP FIRST AROUND THE CONNECTICUT RIVER VALLEY BY EARLY AFTERNOON AND MOVE EAST. EXPECT THE CHANCE OF SVR WX IN NEW HAMPSHIRE WITH A SECOND AREA OF THUNDERSTORMS EXPECTED BY EARLY EVENING. HRRR SHOWS THIS BAND OF STORMS MOVING INTO WESTERN NEW HAMPSHIRE BETWEEN 21Z AND 22Z. THIS LINE WILL MOVE OFF THE COAST BY 01Z. PREVIOUSLY... THE MAIN FORECAST CONCERNS TODAY REVOLVE AROUND THE CHANCES FOR SEVERE THUNDERSTORMS THIS AFTERNOON AND EVENING. A SHORT WAVE TROUGH WILL PASS ACROSS THE CWA EARLY THIS MORNING AND BE ASSOCIATED WITH VARIABLE CLOUDINESS AND PERHAPS A FEW SPRINKLES HERE AND THERE. HOWEVER...PLENTY OF SFC HEATING SHOULD OCCUR FROM LATE MORNING ON THROUGH THE MID AFTERNOON HOURS...AND THIS WILL AID IN DESTABILIZATION. ANOTHER SHORT WAVE TROUGH WILL APPROACH FROM THE WEST THIS AFTERNOON. THIS TROUGH SHOULD AID IN THE DEVELOPMENT OF THUNDERSTORMS ACROSS UPSTATE NY AND VT DURING THE AFTERNOON HOURS TODAY. THESE STORMS ARE EXPECTED TO ADVECT INTO NEW HAMPSHIRE BY LATE AFTERNOON. THERE ARE A FEW PROS AND CONS WITH TODAY/S SETUP AS IT RELATES TO SEVERE WEATHER POTENTIAL TODAY. DETRIMENTAL FACTORS INCLUDE WEAK MID LEVEL LAPSE RATES AND THE ABSENCE OF REAL RICH MOISTURE IN THE BOUNDARY LAYER. THOSE FACTORS SHOULD ALLOW FOR LESS THAN 1000 J/KG MLCAPE AND SO-SO UPDRAFT VELOCITIES. HOWEVER...STRENGTHENING MID LEVEL UNIDIRECTIONAL FLOW LATE IN THE DAY WILL RESULT IN INCREASING DEEP LAYER SHEAR VALUES IN THE MIDST OF IMPROVING UPPER SUPPORT WITH THE APPROACH OF THE SHORT WAVE TROUGH. IN ADDITION...WE SHOULD SEE A GOOD 20 DEGREE DEWPOINT DEPRESSION IN MANY AREAS BY MID AFTERNOON AS TEMPERATURES RISE INTO THE 80S. THEREFORE...WHILE WE AREN/T EXPECTING A SEVERE WEATHER OUTBREAK TODAY...WE FEEL THAT THE POTENTIAL EXISTS FOR WIDELY SCT SEVERE STORMS BY LATE AFTERNOON ACROSS NEW HAMPSHIRE. OUR BEST GUESS IS THAT ONE OR MORE BOWING SEGMENTS WILL MOVE ACROSS THE CT RIVER BY LATE AFTERNOON...WITH THE MAIN THREAT BEING WIND DAMAGE. HAVE INCLUDED DAMAGING WIND WORDING IN THE FORECAST FOR NH GIVEN THE PRESENCE OF INCREASING UNIDIRECTIONAL FLOW AND STEEP LOW LEVEL LAPSE RATES. HAIL AND TORNADO THREATS ARE NON-ZERO BUT ARE SECONDARY TO THE DAMAGING WIND THREAT. FURTHER EAST IN MAINE...THE SEVERE WEATHER THREAT WILL BE LESS...BUT A GUSTY WIND/FREQUENT LIGHTNING RISK COULD BE IN THE CARDS AS NH CONVECTION PUSHES EAST AND WEAKENS DURING THE EARLY EVENING HOURS. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... EVENING CONVECTION SHOULD DIMINISH SIGNIFICANTLY BY MIDNIGHT IF NOT BEFORE. WE ARE EXPECTING A MAINLY DRY NIGHT AFTER ANY CONVECTION MOVES THROUGH. ANOTHER SHORT WAVE TROUGH APPROACHES TUESDAY...AND THE SAME GENERAL SETUP AS MONDAY IS EXPECTED. THEREFORE...THE POSSIBILITY FOR THUNDERSTORMS EXISTS MAINLY DURING THE LATE AFTERNOON AND EVENING HOURS...SOME POSSIBLY SEVERE. HIGHS SHOULD BE WELL INTO THE 80S TO AROUND 90. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... COLD FRONT WILL APPROACH FROM THE WEST TUESDAY NIGHT AND WILL CROSS THE REGION ON WEDNESDAY. AN AREA OF SHOWERS AND THUNDERSTORMS AHEAD OF THE FRONT WILL CROSS THE AREA TUESDAY NIGHT. ACTUAL FRONTAL BOUNDARY WILL LINGER OVER THE REGION ON WEDNESDAY AND MAY PRODUCE ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS BEFORE PUSHING OFFSHORE...ALTHOUGH MOISTURE MAY BE A LIMITING FACTOR. HIGH TEMPS ACROSS THE REGION WILL TOP OUT IN THE UPPER 70S TO MID 80S. SECONDARY COLD FRONT APPROACHES FROM THE WEST WEDNESDAY NIGHT AND WILL CROSS THE REGION ON THURSDAY. WILL SEE A CHANCE OF SHOWERS AND THUNDERSTORMS WEDNESDAY NIGHT AND EARLY THURSDAY BEFORE COOLER AND DRIER PUSHES IN BEHIND THE FRONT IN THE AFTERNOON. HIGH TEMPS WILL RANGE THROUGH THE 70S IN THE NORTH TO THE LOWER 80S IN THE SOUTH. FAIR THURSDAY NIGHT AS HIGH PRESSURE BUILDS IN FROM THE WEST. LOWS WILL RANGE THROUGH THE 50S. FAIR WEATHER WILL CONTINUE ON FRIDAY AS HIGH PRESSURE CRESTS OVER THE REGION. HIGH PRESSURE WILL SHIFT OFFSHORE FRIDAY NIGHT. SHORTWAVE WILL APPROACH FROM THE WEST ON SATURDAY BRINGING THE THREAT OF LATE DAY SHOWERS AND THUNDERSTORMS WITH BULK OF CONVECTIVE ACTIVITY CROSSING THE REGION SATURDAY NIGHT. && .AVIATION /13Z MONDAY THROUGH FRIDAY/... SHORT TERM...MAINLY VFR CONDITIONS ARE EXPECTED TODAY. HOWEVER...LATE DAY AND EVENING SHOWERS AND THUNDERSTORMS MAY ALLOW FOR LOCAL IFR CONDITIONS...ESPECIALLY IN NH. SOME FOG AND STRATUS WILL BE POSSIBLE AT THE COAST TONIGHT. MORE SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE TUE. LONG TERM...GENERALLY VFR TUESDAY NIGHT THROUGH FRIDAY. && .MARINE... SHORT TERM...SCA FOR HAZARDOUS SEAS IS IN EFFECT FROM NOON TODAY THROUGH TUE MORNING. A FEW 25 KT GUSTS WILL BE POSSIBLE...BUT THE MAIN THREAT WILL BE SEAS BUILDING TO 4 TO 6 FT. LONG TERM...NO PROBLEMS NOTED. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 AM EDT TUESDAY FOR ANZ150-152-154. && $$ TFH

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