Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 250406 AAD AFDGYX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAY ME 1206 AM EDT MON APR 25 2016 .SYNOPSIS... HIGH PRESSURE WILL SHIFT OFFSHORE TONIGHT AND MONDAY. A WARM FRONT WILL LIFT NORTH INTO SOUTHERN AND STALL THERE MONDAY NIGHT AND TUESDAY. THIS WILL BRING SOME PRECIPITATION IN THE SOUTHERN HALF OF NEW HAMPSHIRE AND COASTAL MAINE. SOME OF THIS COULD FALL AS SNOW. COOL HIGH PRESSURE THEN SETTLES IN THROUGH THEN END OF THE WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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1205 AM UPDATE...SLIGHT CHANGES TO ACCOUNT FOR CURRENT TRENDS IN TEMPERATURES AND DEW POINTS. OTHERWISE FORECAST IS ON TRACK. 925 PM UPDATE...JUST A FEW MINOR ADJUSTMENTS TO THE GOING FORECAST BASED ON LATEST TRENDS IN OBSERVATIONAL DATA. JUST SOME THIN CIRRUS OVERSPREADING SOUTHERN ZONES THIS EVENING... OTHERWISE CLEAR. WHERE WINDS ARE CALM... TEMPS WILL RADIATE QUITE WELL TONIGHT. AS A RESULT... WE HAVE LOWERED MINS A BIT. 620 PM UPDATE...HAVE UPDATED THE FORECAST MAINLY FOR MINOR ADJUSTMENTS TO TEMPS AND WINDS BASED ON LATEST OBSERVATIONAL TRENDS. OVERALL...WINDS WILL DIMINISH THIS EVENING AND SKIES WILL REMAIN CLEAR. PREVIOUSLY... WINDS WILL DIMINISH WITH JUST CIRRUS SKIMMING THE NRN AND SRN ZONES TONIGHT. LOWS WILL DROP DOWN INTO THE MID 20S NORTH TO LOW 30S SOUTH.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM TUESDAY/... SFC HIGH CONTINUE TO SHIFT SE AWAY FROM THE CWA ON MON. AND WINDS SHIFT TO SW BY LATER IN THE DAY. WEAK LOW WILL BEGIN TRACK EWD OUT OF THE GREAT LAKES LATE MONDAY AND WILL SEE CLOUDS BEGIN TO THICKEN UP DURING THE DAY. COULD SEE A FEW LIGHT SHRA IN SRN NH BEFORE SUNSET...BUT BULK OF ANY RAFL WILL HOLD OFF UNTIL AT LEAST MON EVENING. HIGHS WILL GENERALLY BE IN THE 50S AGAIN...TO AROUND 60 IN SRN NH. MODELS /THE GFS AND EURO ANYWAY/ ARE IN BETTER AGREEMENT THAT THE WEAK SFC LOW TRACKS S OF THE CWA...AND WE STAY ON THE COLD SIDE OF THE SYSTEM. MODELS ALSO AGREE THAT WE GET SOME PRECIP INTO SOUTHERN HALF OF NH AND THE COASTAL PLAIN OF ME MON NIGHT INTO TUE...AND WILL BE SEEING A SURGE OF COLDER AIR FORM THE N...WHICH COULD PRODUCE SOME SNOW AT THE HIGHER ELEVATIONS MON NIGHT. IF ANY SNOW MAKES IT FURTHER SOUTH...THAT WILL LIKELY BE TUE MORNING AND INCLUDED IN THE LONG TERM SECTION. LOWS WILL LIKE OCCUR AROUND MIDNIGHT WITH TEMPS STEADY AFTER THAT...GENERALLY IN THE UPPER 20S N...TO THE MID TO UPPER 30S IN THE SOUTH. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... MAIN WX CONCERN REMAINS AT THE BEGINNING OF THE EXTENDED. A WEAK WAVE WILL TRAVEL ALONG THE BAROCLINIC ZONE HUNG UP OVER NEW ENGLAND. MID LEVEL FRONTOGENESIS INCREASES SHARPLY BY TUE MORNING...THOUGH THE BEST WAA LOOKS TO REMAIN S OF THE FORECAST AREA. AS A RESULT...FORCING FOR ASCENT WILL BE MODEST BUT NOT OVERLY STRONG. STILL A BAND OF PRECIP ORIENTED FROM NW TO SE LOOKS TO DEVELOP AND SLIDE ACROSS THE SRN HALF OF THE AREA. SINCE YESTERDAY THE 24.12Z GFS HAS COME MORE INTO LINE WITH THE ECMWF...WITH UPPER LOW OVER CANADA PUSHING PRECIP FARTHER S. NRN PARTS OF THE FORECAST AREA LOOK TO REMAIN DRY ALOFT...AND PRECIP GENERATION WILL BE TOUGHER TO COME BY IN THAT CASE. THE BIGGEST QUESTION WILL BE SFC TEMPS TUE AS PRECIP IS MOST LIKELY HEAVIEST. THE 24.12Z NAM FORECAST SOUNDINGS FOR THE AREA POINT TOWARDS TEMPS NEAR FREEZING...EVEN DURING THE DAYLIGHT...AND ACCUMULATING SNWFL. WITH A GENERAL LACK OF PRECIP THE GFS FAILS TO WET BULB COOL...AND TEMPS REMAIN IN THE 40S. HOWEVER...IF PRECIP WERE TO FALL THRU THE COLUMN TEMPS WOULD WET BULB TO VERY NEAR FREEZING. SO THERE IS SOME SNWFL ACCUMULATION IN THE FORECAST GRIDS...MAINLY FOR THE HIGHER TERRAIN RIGHT NOW WHERE CONFIDENCE IS HIGHEST. LOWER ELEVATIONS WILL HAVE TO KEEP AN EYE ON TRENDS...AS AT LEAST FLAKES IN THE AIR IS LOOKING MORE AND MORE LIKELY. AS OF 24.00Z THE ECMWF EPS EVEN HAD CHANCES OF 1 OR MORE INCH OF SNWFL GREATER THAN 50 OR 60 PERCENT FOR SRN NH. THERMAL PROFILES SUPPORT IT...IT IS JUST A MATTER OF WHETHER ENOUGH PRECIP FALLS AT A HEAVY ENOUGH RATE. BEYOND TUE...CANADIAN UPPER LOW CONTINUES TO BE THE MAIN DRIVER OF OUR WX. FLOW BECOMES MORE CONFLUENT ALOFT...SO IT SHOULD BE DRY...BUT TEMPS ALOFT REMAIN BELOW NORMAL FOR THIS TIME OF YEAR. SO THE EXTENDED INTO THE WEEKEND WILL FEATURE LOW POP AND SEASONABLY COOL TEMPS. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... SHORT TERM...VFR TODAY THROUGH MONDAY. COULD SEE SOME MVFR TO IFR I RA AND LOW CIGS LATE MON NIGHT...ESPECIALLY AT KLEB/KCON/KMHT/KPSM/KPWM. LONG TERM...A WAVE ALONG THE FRONT BRINGS PRECIP TO MAINLY THE SRN HALF OF THE AREA INTO TUE. EXPECTING MVFR CONDITIONS ALONG AND S OF A LEB TO PWM LINE...BUT SOME SNWFL COULD MIX IN AND LEAD TO LOCAL IFR CONDITIONS...ESPECIALLY FOR WRN NH. ONCE FRONT SLIPS S OF THE REGION...VFR CONDITIONS PREVAIL THRU THE END OF THE WORK WEEK. && .MARINE... SHORT TERM...NW WINDS WILL GRADUALLY DIMINISH THIS AFTER AND EVENTUALLY TURN SW TONIGHT. THE THEY SHIFT TO NE ON MON NIGHT BUT REMAIN BELOW SCA. LONG TERM...LATE MON NIGHT INTO TUE MORNING WINDS WILL GUST TO NEAR 25 KTS OVER THE WATERS AS FRONT CROSSES THE WATERS. SCA CONDITIONS ARE POSSIBLE IN THIS WINDOW. THE AREA LOOKS TO BE BETWEEN SYSTEMS FOR THE REST OF THE WEEK...WITH GENERAL WLY FLOW STAYING BELOW SCA THRESHOLDS. && .FIRE WEATHER... A FIRE WEATHER WATCH HAS BEEN ISSUED FOR PORTIONS OF MAINE FOR MONDAY WHERE RH VALUES ARE EXPECTED TO DIP TO BETWEEN 15 AND 20 PERCENT WITH FREQUENT WIND GUSTS AROUND 20 MPH. LIGHTER WINDS EXPECTED IN NH HAVE PRECLUDED THE ISSUANCE OF A WATCH AT THIS TIME. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...FIRE WEATHER WATCH FROM 11 AM EDT THIS MORNING THROUGH THIS AFTERNOON FOR MEZ007>009-012>014-018>022-025>028. NH...NONE. MARINE...NONE.
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&& $$ NEAR TERM...HANES SHORT TERM...CEMPA LONG TERM...LEGRO

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