Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 030024 AAA AFDGYX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAY ME 824 PM EDT SAT MAY 2 2015 .SYNOPSIS... HIGH PRESSURE OFFSHORE WILL BRING A SOUTHERLY FLOW OVER THE NORTHEAST AND TRANSPORT WARMER AIR INTO THE AREA. SOME AFTERNOON SHOWERS OR A THUNDERSTORM ARE POSSIBLE SUNDAY. A WEAK COLD FRONT WILL CROSS THE AREA MONDAY NIGHT AND EARLY TUESDAY WITH CLOUDS AND SCATTERED SHOWERS. ANOTHER MOISTURE STARVED COLD FRONT WILL CROSS THE AREA WEDNESDAY. A RIDGE OF HIGH PRESSURE FOLLOWS FOR LATE WEDNESDAY INTO FRIDAY. A DEVELOPING ONSHORE FLOW AND AN APPROACHING WARM FRONT WILL MAKE THE WEATHER INCREASINGLY UNSETTLED FOR THE UPCOMING WEEKEND. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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.UPDATE... CUMULUS CLOUDS HAVE DISSIPATES. LOW STRATUS DECK OFFSHORE IS HAVING A HARD TIME MOVING INLAND IN DRIER AIR. SOME HIGHER CIRRUS CLOUDS WERE MOVING IN FROM THE WEST THIS EVENING. HAVE ADJUSTED TEMPERATURE AND DEW POINT GRIDS AS MUCH WARMER READINGS EXISTED THE LAST HOUR IN NH AND INLAND THAN ALONG THE COAST AND WHERE THE SEABREEZE HAD PENETRATED THIS AFTERNOON. OVERNIGHT READINGS WILL BE A BIT OF A CHALLENGE BECAUSE OF THESE REASONS. SREF AND WRF WANT TO SHOW FOG OVER AUGUSTA AND THE MIDCOAST WITH MUCH LESS IN UNSHELTERED AREAS TO THE EAST... BUT THIS SEEMS UNLIKELY.
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&& PREVIOUS DISCUSSION...LOW CLOUDS WHICH AFFECTED COASTAL AREAS LAST NIGHT ONLY RETREATED JUST OFFSHORE TODAY. WITH THE SOUTHERLY FLOW DEVELOPING TODAY IN RESPONSE TO HIGH PRESSURE SHIFTING EAST AND A SEA BREEZE... EXPECT THIS LOW CLOUD LAYER TO BE ADVECTED BACK ONSHORE EARLY THIS EVENING. TEMPERATURES TONIGHT SHOULD NOT BE QUITE AS COLD AS LAST NIGHT AND SHOULD NOT HAVE TO WORRY ABOUT ANY FROST OR FREEZE HEADLINES. HOWEVER... THIS FORECASTER THOUGHT THE SAME THING LAST NIGHT AND THERE WERE A FEW SPOTS THAT DROPPED BELOW FREEZING. WENT A LITTLE BELOW THE BLEND OF SHORT TERM GUIDANCE FOR LOW TEMPERATURES TONIGHT BUT EXPECT THE MARINE CLOUD COVER TO MOVE IN EARLIER TONIGHT AND PREVENT AS MUCH COOLING. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
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MORNING LOW CLOUDS MAY HOLD ON A LITTLE LONGER ON SUNDAY BEFORE BURNING OFF WITH THE MORNING SUN. IT WILL BE WARM AGAIN... EVEN WARMER THAN TODAY... WITH HIGHS EXPECTED IN THE 60S AND 70S AWAY FROM THE COAST. INCREASING SURFACE DEW POINTS WILL ALSO SET THE STAGE FOR SOME AFTERNOON INSTABILITY CLOUDS AND SHOWERS. WEAK SHORTWAVE TROUGH ALOFT MOVES OUT OF QUEBEC AND THROUGH THE CENTER OF THE FORECAST AREA ON SUNDAY. THIS FEATURE IS OBSERVED BETTER BY A SLIGHT COLD POCKET AT AROUND 700 MB ALOFT. THIS WILL COMBINE WITH THE INCREASING LOW LEVEL MOISTURE AND DIURNAL HEATING TO PRODUCE INSTABILITY DURING THE AFTERNOON. EXPECT THE HILLS AND MOUNTAINS TO EXPLODE IN CUMULUS CLOUDS LATE IN THE MORNING AND GROW INTO SHOWERS OR EVEN AN ISOLATED THUNDERSTORM DURING THE AFTERNOON. AREAS NEAR THE COAST WILL LIKELY BE PROTECTED BY THE MARITIME AIR MASS. AFTERNOON SHOWERS DISSIPATE WITH THE LOSS OF STRONG HEATING. WITH GREATER MOISTURE LEVELS AROUND TEMPERATURES SHOULD BOTTOM OUT IN THE 40S. DID UNDERCUT GUIDANCE NUMBERS AGAIN FOR FORECAST LOWS ESPECIALLY IN VALLEY LOCATIONS.
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&& .LONG TERM /MONDAY THROUGH SATURDAY/... THE MODELS ARE IN GENERAL AGREEMENT ON THE LONG WAVE PATTERN FOR THE ENTIRE FORECAST PERIOD. WE BEGIN THE WORK WEEK WITH RIDGING AND A MILD SOUTHERLY FLOW. AN IMPULSE RACING EAST WILL DRIVE A WEAK COLD FRONT THROUGH THE AREA MONDAY NIGHT/EARLY TUESDAY WITH CLOUDS AND SCATTERED CONVECTION. WEAK RIDGING AND AN OFFSHORE FLOW BEHIND THIS FIRST FRONT WILL PROVIDE ANOTHER WARM DAY TUESDAY. A SECOND IMPULSE DRIVES ANOTHER WEAK AND MOISTURE STARVED COLD FRONT ACROSS THE AREA WEDNESDAY. BEHIND THIS SECOND FRONT...WE`LL SEE HIGH PRESSURE BUILDING BY TO OUR NORTH THURSDAY. THE FLOW TURNS ONSHORE...AND WITH AN UPPER RIDGE BUILDING TO OUR WEST...A WARM FRONT DEVELOPS ACROSS THE REGION THURSDAY NIGHT AND FRIDAY. OVERRUNNING PRECIPITATION AND SOME DRIZZLE AND FOG IS POSSIBLE LATE FRIDAY AND SATURDAY. UNFORTUNATELY...IT COULD TAKE THE BALANCE OF THE WEEKEND TO PUSH THE WARM FRONT TO OUR NORTH IN ADVANCE OF THE NEXT IMPULSE AND SURFACE LOW APPROACHING FROM THE GREAT LAKES. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... SHORT TERM...LOW CLOUDS WHICH PLAGUED THE AREA SATURDAY MORNING ONLY RETREATED A SHORT WAYS OFFSHORE. EXPECT THIS AREA OF CLOUDS TO MOVE ONSHORE FAIRLY QUICKLY THIS EVENING. COLD ONSHORE FLOW IS QUITE STRONG AND WITH THE LOSS OF DAYTIME HEATING AND MIXING IT SHOULD BE FAIRLY EASY TO CLOUD BACK IN. CONFIDENCE IS FAIRLY HIGH THAT MOST AREAS FROM PORTSMOUTH TO ROCKLAND WILL SEE IFR OR WORSE CONDITIONS THIS EVENING. VISIBILITY COULD ALSO BE IMPACTED. LOW CLOUDS BURN OFF A LITTLE LATER SUNDAY MORNING THAN THEY DID SATURDAY MORNING BUT SHOULD GIVE WAY TO VFR CONDITIONS. AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE IN THE MOUNTAINS DURING THE AFTERNOON. LONG TERM... MONDAY NIGHT - TUESDAY MORNING...SCATTERED MVFR POSSIBLE IN SHOWERS. && .MARINE... SHORT TERM...HIGH PRESSURE OVER THE GULF OF MAINE BRINGS LIGHT WINDS AND NEARLY CALM SEAS. PRIMARY WIND FLOW WILL BE OUT OF THE SOUTH ESPECIALLY DURING THE AFTERNOON. LONG TERM... MONDAY EVENING - TUESDAY...SMALL CRAFT WINDS AND SEAS ARE POSSIBLE. WEDNESDAY EVENING - THURSDAY MORNING...SMALL CRAFT WINDS AND SEAS ARE POSSIBLE. && .FIRE WEATHER... WARM WEATHER WILL BRING LOW AFTERNOON HUMIDITY LEVELS BUT WINDS WILL REMAIN LIGHT FOR THE NEXT FEW DAYS. THERE WILL BE A CHANCE OF A SHOWER OR ISOLATED THUNDERSTORM SUNDAY AFTERNOON MAINLY OVER THE MORE MOUNTAINOUS REGIONS. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE... FIRE WEATHER...

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