Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 210653 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 253 AM EDT TUE MAY 21 2013 .SYNOPSIS...
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A FRONT WILL REMAIN STALLED TO OUR SOUTH THROUGH TONIGHT BEFORE RETURNING NORTH AS A WARM FRONT ON WEDNESDAY.
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&& .NEAR TERM /THROUGH TODAY/...
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AT 06Z...WEST-EAST ORIENTED SURFACE FRONT EXTENDED FROM NEAR LAKE ONTARIO THROUGH SOUTHERN NEW ENGLAND. AN IMPULSE EVIDENT ON GOES WATER VAPOR OVER THE EASTERN GREAT LAKES WAS RACING EAST ACCOMPANIED BY A BROKEN AREA OF CONVECTION AS DEPICTED ON NWS 88D DOPPLER MOSAIC. THIS ACTIVITY WILL RACE EASTWARD AND REACH THE FORECAST AREA TOWARDS 12Z. IMPULSE AND ASSOCIATED CONVECTION WILL EXIT THE AREA DURING THE AFTERNOON WITH LINGERING CLOUDS AND SPOTTY SHOWERS AND DRIZZLE IN ONSHORE FLOW TO THE NORTH OF THE STALLED BOUNDARY. TEMPERATURES MAINLY IN THE 50S TODAY WITH A FEW LOW 60S POSSIBLE WELL INLAND AWAY FROM THE COAST.
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&& .SHORT TERM /TONIGHT THROUGH 6 PM WEDNESDAY/...
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THE NEXT BATCH OF SHOWERS ARRIVE TONIGHT AS ANOTHER IMPULSE AND ASSOCIATED SURFACE LOW BEGIN TO GRADUALLY PUSH THE SURFACE BOUNDARY NORTHWARD AS A WARM FRONT. ON WEDNESDAY...THE BOUNDARY CONTINUES NORTHWARD WITH SOUTHERN AND WESTERN SECTIONS ENJOYING SUMMERTIME WARMTH AND HUMIDITY IN THE WARM SECTOR WITH HIGHS APPROACHING 80F. FOR NORTHERN AND EASTERN SECTIONS AS WELL AS NEAR THE COAST...MORE CLOUDS OR MARINE INFLUENCE WILL LIMIT HIGH TEMPERATURES MAINLY TO THE 60S. STEADIER SHOWERS AND ISOLATED THUNDER WITH THE WARM FRONT WILL BE REPLACED BY SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS IN THE WARM SECTOR.
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&& .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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BY 00Z THURSDAY A MORE PROGRESSIVE UPPER FLOW PATTERN DEVELOPS AS THE CLOSED UPPER LOW THAT HAD BEEN OVER THE CENTRAL PART OF THE COUNTRY FOR THE FIRST PORTION OF THE WEEK IS REABSORBED INTO THE HEMISPHERIC FLOW AS A TROUGH OVER THE GREAT LAKES. THIS TROUGH WILL THEN TRANSLATE EASTWARDS THROUGH THE DAY ON FRIDAY... DRAGGING A COLD FRONT THROUGH LATE THURSDAY AS THE SURFACE LOW TRACKS UP THE ST. LAWRENCE RIVER VALLEY. WITH THE FRONT ARRIVING INTO WESTERN NH IN THE AFTERNOON THUNDERSTORMS ARE LIKELY AS MID-DAY HEATING COMBINED WITH HEIGHT FALLS ALOFT HELP TO DESTABILIZE THE ATMOSPHERE. THE BIGGEST IMPEDIMENT TO CONVECTIVE INITIATION APPEARS TO BE THE POTENTIAL FOR WIDE SPREAD CLOUD COVER THROUGH THE MORNING THURSDAY AS MOISTURE MOVES IN IN THE EARLY MORNING AND SHOWERS SHOULD BE ONGOING THROUGHOUT THE DAY, HOWEVER STRONG FORCING ALONG THE FRONT AND A GOOD WIND SHIFT AND SURFACE CONVERGENCE SHOULD RESULT IN SOME THUNDER FOR THE AFTERNOON. FRIDAY THE LONG WAVE TROUGH PUSHES OUT TO SEA.... GFS SUGGEST A QUICK MOVING SHORT WAVE COULD CAUSE LINGERING SHOWERS INTO THE FIRST PORTION OF FRIDAY...HOWEVER HAVE LOW CONFIDENCE IN SUCH A TRANSIENT FEATURE AND HAVE OPTED TO GO WITH CLEARING EARLIER IN THE DAY. ALL GUIDANCE AGREES ON THE LOW BEING REPLACED BY A HIGH BUILDING IN ALLOWING CLEAR SKIES AND WARM TEMPERATURES BY FRIDAY EVENING FOR THE START OF THE HOLIDAY WEEKEND. THE HIGH WILL REMAIN THROUGH SATURDAY AND INTO SUNDAY WHEN ANOTHER BOUNDARY STALLING TO OUR SOUTH BRING THE POTENTIAL FOR SHOWER THROUGH THE SOUTHERN PORTIONS OF THE AREA FOR MONDAY.
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&& .AVIATION /06Z TUESDAY THROUGH SATURDAY/...
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SHORT TERM /THROUGH WEDNESDAY/...MVFR WITH AREAS OF IFR IN FOG AND DRIZZLE THROUGH TONIGHT. BECOMING VFR WED WITH SCATTERED MVFR IN SHOWERS AND LCL BRIEF IFR IN THUNDERSTORMS. LONG TERM... WEDNESDAY NIGHT WILL SEE IFR FOG AND SHOWERS IN THE MOUNTAINS... WITH MVFR AND POSSIBLE PERIODS OF IFR ON THE COASTAL PLAIN. AFTERNOON THUNDERSTORMS MAY IMPACT... ESPECIALLY IN NEW HAMPSHIRE. CONDITIONS WILL RETURN TO VFR FOR THE WEEKEND.
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&& .MARINE...
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SHORT TERM /THROUGH WEDNESDAY/...QUIET ON THE WATERS WITH ONLY ISSUE VSBY RESTRICTIONS IN FOG AND PRECIPITATION. LONG TERM... SEAS WILL BUILD UNDER SOUTHWESTERLY FLOW WEDNESDAY NIGHT AND INTO THURSDAY.. WITH SCA FOR HIGH SEAS MOST LIKELY BY MIDDAY ON THURSDAY. AFTER THE WINDS SHIFT NORTHWESTERLY SEAS WILL DIMINISH WITH RELATIVELY CALM AND FLAT CONDITIONS FOR THE WEEKEND.
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&& .FIRE WEATHER...
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WITH DAMP WEATHER EXPECTED FOR MUCH OF THE WEEK ALONG WITH HIGHER RELATIVE HUMIDITY VALUES AND GREEN UP...FIRE WEATHER DANGER SHOULD REMAIN LOW THROUGH THE WEEK.
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&& .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ ES/CURTIS

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