Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 311430 AAA AFDGYX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAY ME 1030 AM EDT THU JUL 31 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD IN FROM THE EAST TODAY THROUGH FRIDAY. A WARM FRONT WILL LIFT NORTH FROM THE MID ATLANTIC STATES FRIDAY NIGHT AND WILL STALL ALONG THE SOUTHERN NEW ENGLAND COAST SATURDAY THROUGH SUNDAY. WEAK LOW PRESSURE WILL DEVELOP ON THE FRONT AND WILL TRACK NORTHEAST THIS WEEKEND. A TRAILING COLD FRONT WILL PUSH OFFSHORE MONDAY NIGHT. WEAK HIGH PRESSURE WILL BUILD IN FROM THE WEST TUESDAY THROUGH WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/...
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UPDATE...CLOUD COVER LEADING THE APPROACHING S/WV TROF WILL INHIBIT MAX HEATING POTENTIAL ACROSS WRN NH TODAY. HAVE ADJUSTED TEMPS ACCORDINGLY. THAT BEING SAID...VIGOROUS S/WV WILL STILL HAVE THE POTENTIAL TO PRODUCE SOME SEVERE WX. ESPECIALLY CONSIDERING THE LOW FREEZING LEVELS. SOME SMALL HAIL AND GUSTY WINDS ARE ALREADY OCCURRING IN ERN NY...AND FURTHER DAYTIME HEATING...HOWEVER MINIMAL...WILL ONLY LEAD TO CONTINUED DESTABILIZATION. HI-RES MODEL GUIDANCE SEEMS TO HAVE A GOOD HANDLE ON THE PLACEMENT OF FORCING THIS MORNING...SO HAVE BLENDED IN THE LATEST RUNS TO THE TODAY PORTION OF THE FORECAST. PREVIOUSLY... THE MAIN FORECAST CONCERN TODAY REVOLVES AROUND THE CHANCE FOR SEVERE THUNDERSTORMS. CAPE VALES ARE EXPECTED TO BE RELATIVELY LOW TODAY WITH MLCAPE VALUES EXPECTED TO PEAK IN THE 500-800 J/KG RANGE. HOWEVER...THE APPROACH OF A STRONG SHORT WAVE TROUGH WITH ATTENDANT ANOMALOUSLY LOW MID LEVEL TEMPERATURES /500MB TEMPS AS LOW AS -17C/ AND STRONG MID LEVEL FLOW/DEEP LAYER SHEAR WILL BE SUPPORTIVE OF WIDELY SCT STRONG TO SEVERE THUNDERSTORMS THIS AFTERNOON. WITH SFC DEWPOINTS MIXING OUT INTO THE LOWER TO MID 50S...SFC DEWPOINT DEPRESSIONS SHOULD BE AS HIGH AS 20 TO 25 DEGREES THIS AFTERNOON AS SFC TEMPS PUSH INTO THE 70S. THIS WILL CREATE AN ENVIRONMENT CONDUCIVE FOR STRONG WIND GUSTS THROUGH EVAPORATIONAL COOLING. IN ADDITION...SOME SEVERE HAIL WILL BE POSSIBLE AS WELL WITH SUCH COLD TEMPERATURES ALOFT. SEVERAL MODES OF CONVECTION ARE POSSIBLE TODAY...WITH ORGANIZED MULTICELLS LIKELY ALONG WITH A FEW BOWING SEGMENTS AND PERHAPS A COUPLE OF SUPERCELLS GIVEN THE DEEP LAYER SHEAR VALUES. STORMS ARE EXPECTED TO INITIATE AROUND MIDDAY...WITH FIRST PREFERENCE GIVEN TO NH AS THE FORCING FOR ASCENT ASSOCIATED WITH THE SHORT WAVE TROUGH WILL MOVE INTO THAT AREA OF THE CWA FIRST. HOWEVER...A FEW CELLS MAY INITIATE IN MAINE AROUND THAT TIME ALONG SUBTLE CONVERGENCE ZONES AND IN AREAS OF DIFFERENTIAL HEATING. HIGHEST POPS WILL BE ACROSS NORTHERN ZONES TODAY. EARLY ON IN THE MORNING...STRATUS AND AREAS OF DENSE FOG WILL BE PRESENT IN RIVER VALLEYS AS WELL AS MUCH OF THE CWA NORTHEAST OF PORTLAND. THIS SHOULD LIFT EARLY ON THIS MORNING.
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&& .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... ANY SHOWER AND THUNDERSTORM ACTIVITY WILL WANE QUICKLY EARLY THIS EVENING WITH THE LOSS OF DAYTIME HEATING. THE BULK OF THE NIGHT IS EXPECTED TO BE FAIR...WITH AREAS OF FOG ONCE AGAIN DEVELOPING LATE. ON FRIDAY...COLD AIR ALOFT WILL REMAIN. THIS WILL ACT IN TANDEM WITH CONTINUED SOUTHERLY LOW LEVEL SFC FLOW TO AID IN A FEW SHOWERS OR THUNDERSTORMS DURING THE AFTERNOON HOURS. HOWEVER...ACTIVITY IS NOT EXPECTED TO BE AS WIDESPREAD AS TODAY AND ISN/T EXPECTED TO BE SEVERE. JUST LOW CHANCE POPS AT THIS TIME. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... WARM FRONT WILL LIFT NORTH FROM THE MID ATLANTIC COAST FRIDAY NIGHT AND THIS BOUNDARY WILL HANG UP ALONG THE SOUTHERN NEW ENGLAND COAST BY SATURDAY MORNING. NET RESULT WILL BE INCREASING HIGH CLOUDS OVERNIGHT. STILL APPEARS ANY ASSOCIATED PRECIP WILL REMAIN WELL SOUTH OF THE REGION. LOW TEMPS WILL RANGE FROM THE MID 50S TO LOWER 60S. MAIN QUESTION WILL BE SENSIBLE WEATHER OVER THE WEEKEND. THE ECMWF CONTINUES TO ADVERTISE A SOUTHERN STREAM WAVE AFFECTING THE REGION SATURDAY WITH WIDESPREAD RAIN/SHOWERS. THE GFS CONTINUES TO KEEP THE ACTIVITY OFFSHORE UNTIL SUNDAY NIGHT. THE ECMWF HAS SHOWN GOOD RUN TO RUN CONSISTENCY WITH THE WET SATURDAY SCENARIO...SO PLACED THE HIGHEST POPS OF THE WEEKEND ON SAT. HOWEVER...CONFIDENCE REMAINS A BIT LOW AT THIS TIME. EXPECT GRADUAL CLEARING MONDAY NIGHT AS LOW PRESSURE CONTINUES OFF TO THE EAST AND DRIER NORTHWEST FLOW SETS UP BEHIND A WEAK COLD FRONT. HIGH PRESSURE WILL BUILD IN FROM THE WEST FOR TUESDAY AND WEDNESDAY AS COOL SUMMER WEATHER CONTINUES IN THE NORTHEAST. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... SHORT TERM...IFR OR LOWER CONDITIONS EARLY THIS MORNING WILL GIVE WAY TO VFR AS THE MORNING PROGRESSES. RKD MAY HOLD ONTO IFR LONGER...PERHAPS INTO THE AFTERNOON. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP THIS AFTERNOON WITH ATTENDANT THREAT FOR LOWER CONDITIONS...GUSTY SFC WINDS...AND HAIL. LOWER CONDITIONS MAY ONCE AGAIN DEVELOP LATE TONIGHT IN SOME FOG AND STRATUS...BUT CHANCES APPEAR LOWER THAN WHAT WE ARE SEEING EARLY THIS MORNING. FRIDAY IS EXPECTED TO BE MAINLY VFR WITH SCT AFTERNOON SHOWERS. LONG TERM...MVFR OR LOWER POSSIBLE ON SATURDAY IN SHOWERS...AND POSSIBLY AGAIN SUNDAY NIGHT. && .MARINE... SHORT TERM...SUB-SCA CONDITIONS ARE EXPECTED TODAY THROUGH FRIDAY. HOWEVER...AREAS OF DENSE FOG WILL BE PRESENT FROM TIME TO TIME...ESPECIALLY OFF THE MID COAST OF MAINE. A FEW THUNDERSTORMS MAY MOVE ACROSS THE WATERS BY LATE AFTERNOON TODAY. LONG TERM...NO PROBLEMS NOTED. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...NONE. NH...NONE. MARINE...NONE.
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&& $$ NEAR TERM...LEGRO

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