Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 271022 AAA AFDGYX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAY ME 622 AM EDT MON APR 27 2015 .SYNOPSIS... PERSISTENT UPPER LEVEL LOW PRESSURE OVER THE CANADIAN MARITIMES WILL SHIFT SW INTO THE GULF MAINE TODAY SUPPORTING SHOWER ACTIVITY. THE LOW WILL SHIFT SLOWLY EAST TUESDAY ALLOWING HIGH PRESSURE TO BUILD IN WEDNESDAY AND THURSDAY. LOW PRESSURE PASSES SOUTH OF THE AREA FRIDAY... WITH HIGH PRESSURE BUILDING BACK IN BEHIND IT NEXT WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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.UPDATE... A FEW SHOWERS NOW ENTERING SOMERSET AND FRANKLIN COUNTIES THIS MORNING WITH A FEW RETURNS OVER SOUTHERN NH. THERE IS LIKELY NOTHING REACHING THE GROUND ESPECIALLY OVER SOUTHERN NH. HAVE ADJUSTED POPS BASED ON LATEST MODELS... OTHERWISE FORECAST IS IN FOOD SHAPE.
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&& PREVIOUS DISCUSSION... STACKED LOW PRESSURE MOVES FROM NOVA SCOTIA TODAY TOWARDS THE GULF OF MAINE. THIS WILL HELP TRIGGER WIDESPREAD SHOWERS THROUGHOUT THE DAY AND PUSH A BACKDOOR BOUNDARY THROUGH THE REGION THIS EVENING. RAINFALL AMOUNTS WILL BE LIGHT. HIGHS WILL ONLY WARM INTO THE MID 40S TO MID 50S THANKS TO CLOUD COVER. THE WARMER TEMPERATURES WILL BE IN SOUTHERN NH WHERE CLEARING MAY OCCUR THIS AFTERNOON. GUSTY NORTH WINDS WILL MAKE IT SEEM COOLER HOWEVER. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... LOW PRESSURE WILL BECOME MORE COMPACT AND PULL AWAY TO THE EAST TONIGHT. MOST SHOWERS OVER NH AND WESTERN MAINE SHOULD BE OVER BY THE EVENING WITH SOME LINGERING RAIN OVER THE MIDCOAST AND IN THE HIGHER TERRAIN WHERE FLURRIES MAY FALL. TEMPERATURES DROP AS THE BACKDOOR COLD FRONT MOVES THROUGH FROM NE TO SW. MOST LOCATIONS SHOULD DROP INTO THE MID TO UPPER 30S WITH SOME LOWER 40S ALONG THE COAST. ON TUESDAY SHOWERS STILL LINGER... AS ALTHOUGH THE UPPER LOW WILL BE TO OUR EAST WE WILL STILL BE DOMINATED BY CYCLONIC FLOW. PRECIPITATION WILL MAINLY BE CONFINED TO THE HIGHER TERRAIN AND DOWNEAST. WIDESPREAD UPPER 50S AND LOWER 60S ARE EXPECTED TUESDAY EXCEPT PERHAPS FOR NORTHERN SECTIONS. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
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LINGERING EFFECTS OF UPPER LOW PRES WILL REMAIN OVER THE REGION WED. SHOWER ACTIVITY LOOKS LESS LIKELY...THOUGH AFTERNOON INCREASE IN CLOUD COVER WILL STAY IN THE FORECAST. FORECAST BECOMES LOW CONFIDENCE BEYOND THU...AS UPPER LOW PRES FROM THE SERN CONUS LOOKS TO DRIFT UNDERNEATH RIDGING OVER THE NORTHEAST. IT WILL BE A COMPLEX PATTERN...WITH INTERACTION BETWEEN THE DEPARTING UPPER LOW PRES...HIGH PRES TO THE N...AND DIGGING S/WV TROF ON THE BACKSIDE OF APPROACHING UPPER LOW. THE 27.00Z GFS IS MOST AGGRESSIVE WITH DIGGING S/WV...ALLOWING SERN UPPER LOW PRES TO LIFT AND PHASE MUCH FARTHER NWD. THIS IS THE MOST PESSIMISTIC OUTCOME...BUT ALSO AN OUTLIER. THE 27.00Z CMC FORECAST KEEPS OUR CURRENT UPPER LOW CLOSER THRU LATE WEEK...LEAVING LITTLE ROOM FOR THE NEXT UPPER LOW TO MOVE NWD. FINALLY THE 27.00Z ECWMF PLAYS THINGS BETWEEN THOSE UPRIGHTS. WEAKER WITH THE BACKSIDE S/WV AND ALSO QUICKER WITH THE DEPARTING UPPER LOW...THIS ALLOWS A COASTAL LOW TO DEVELOP...BUT ALSO REMAIN WELL S OF OUR AREA. FAVORED A 40/40/20 ECMWF/CMC/GFS BLEND FOR POP...WHICH GENERALLY KEEPS CHANCE SHOWERS CONFINED TO SRN THIRD OF THE FORECAST AREA LATE WEEK. THOUGH NE FLOW OVER THE AREA WILL LIMIT THE AMOUNT OF WARMTH WE SEE THRU THE WEEKEND...SO TEMPS REMAIN NEAR NORMAL FOR NOW.
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&& .AVIATION /10Z MONDAY THROUGH FRIDAY/... SHORT TERM...CONDITIONS WILL RANGE FROM VFR TO MVFR TODAY IN LIGHT SHOWERS WITH GUSTY NW WINDS. CEILINGS SHOULD IMPROVE TONIGHT WITH VFR FOR TUESDAY. LONG TERM...VFR CONDITIONS ARE EXPECTED TO PREVAIL IN THE EXTENDED. UPPER LEVEL LOW PRES WILL BEGIN TO DEPART WED...SO ANY MVFR SHOWER CHANCES WILL DIMINISH IN KIND. THE GFS FORECAST OF COASTAL LOW PRES COMING THIS FAR N IS VERY LOW CONFIDENCE AT THIS POINT...SO WILL FAVOR JUST AN INCREASE IN CLOUDS ACROSS SRN ZONES FOR NOW. && .MARINE... SHORT TERM...A BACKDOOR FRONT MOVES ACROSS THE WATERS MONDAY NIGHT WITH GUSTY NORTH WINDS TO FOLLOW. A SCA WILL BE NEEDED FOR LATE MONDAY NIGHT INTO TUESDAY. LONG TERM...CANNOT RULE OUT A PERIOD OF SCA CONDITIONS LATE IN THE WEEK AS A COASTAL LOW PASSES WELL S OF THE WATERS. SUSTAINED NELY FLOW SHOULD AT LEAST BUILD SEAS TO AROUND 5 FT FOR A TIME BEFORE THEY DIMINISH. && .FIRE WEATHER...
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RECENT WIDESPREAD RAINS AS WELL AS GOOD RH RECOVERY EACH NIGHT WILL HELP KEEP FIRE CONCERNS LOW.
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&& .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 11 AM EDT TUESDAY FOR ANZ150>152-154.
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&& $$ HANES/LEGRO

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