Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 182005 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 305 PM EST THU DEC 18 2014 .SYNOPSIS...
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WEAK HIGH PRESSURE WILL START TO BUILD IN THIS EVENING. SOME OCEAN EFFECT SNOW MAY BE POSSIBLE SUNDAY INTO MONDAY DUE TO ONSHORE FLOW. A WEAK LOW WILL LIKELY STRENGTHEN AND PASS TO OUR WEST TUESDAY AND MAY SPREAD LIGHT PRECIP INTO NEW ENGLAND. AN STRONGER AREA OF LOW PRESSURE WILL MOST LIKELY DEVELOP OFF TO OUR WEST ON WEDNESDAY AND POSSIBLY BRING HEAVY RAIN AND STRONG WINDS WEDNESDAY AND INTO CHRISTMAS MORNING.
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&& .NEAR TERM /THROUGH TONIGHT/...
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BLOCKED UPSLOPE SIGNAL IS PRETTY STRONG CURRENTLY...WITH KHIE DROPPING BELOW 2SM VSBY. THIS IS USUALLY A PRETTY GOOD INDICATOR OF HEAVIER SNWFL HEADING INTO NRN COOS COUNTY. SUSPECT A SIMILAR STORY EWD INTO THE WRN ME MTNS. WITH FROUDE NUMBERS FORECAST TO CONTINUE FALLING THRU THE EVENING...WILL KEEP POP CONFINED TO THE NW SIDE OF THE MTN TOPS. SNWFL GRIDS LOOK IN GOOD SHAPE...WITH ADDITIONAL LIGHT ACCUMULATIONS POSSIBLE. HOWEVER SINCE EVENT HAS TRANSITIONED TO MOSTLY THE HIGHER TERRAIN IN LOCALIZED FAVORED AREAS...WINTER WX ADVISORIES WILL BE CANCELLED. CLOUD COVER SHOULD HANG TOUGH TONIGHT...AND GRADIENT WILL REMAIN UP JUST ENOUGH TO KEEP A LIGHT BREEZE GOING. AS SUCH I HAVE BLENDED IN MESOSCALE MODEL 2 M TEMP GUIDANCE...AS WE SHOULDN/T REALLY SEE MUCH IF ANY RADIATIONAL COOLING.
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&& .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
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UPSLOPE SHSN GRADUALLY TAPER OFF AS LIFT OVER THE TERRAIN DECREASES DUE TO THE APPROACHING RIDGE. AS RIDGE MOVES IN ALOFT A BIT OF MID LEVEL MOISTURE LOOKS LIKE IT MAY GET TRAPPED AND SINK SWD ACROSS THE CWFA DURING THE DAY. THE LATEST NAM...GFS...AND CMC DO INDICATE AT LEAST PARTIAL CLOUD COVER...SO HAVE BLENDED THESE MODELS INTO THE LATEST SKY GRIDS. OTHERWISE THE SENSIBLE WX SHOULD BE QUIET FRI.
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&& .LONG TERM /SATURDAY THROUGH THURSDAY/...
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SURFACE HIGH PRESSURE BUILDS NORTH OF THE REGION DURING THE DAY ON SATURDAY AND THEN SLIDES OFF TO THE EAST ON SUNDAY. THIS WILL SET UP RETURN FLOW FOR MONDAY AND TUESDAY. THIS MAY PRODUCE SOME OCEAN EFFECT SNOW SHOWERS BUT AMOUNTS SHOULD BE VERY LIMITED. CLOSED UPPER LEVEL LOW PRESSURE SYSTEM OVER THE WESTERN GREAT LAKES WILL BEGIN TO IMPACT NEW ENGLAND WEATHER AS EARLY AS TUESDAY NIGHT. WEAK DISTURBANCE GETS EJECTED FROM THE BASE OF THE TROUGH ON TUESDAY NIGHT AND WEDNESDAY MORNING. THE SURFACE REFLECTION OF THIS MAY ONLY BE A TROUGH BUT DIFFLUENT FLOW ALOFT WILL PROVIDE ENOUGH INSTABILITY FOR SOME FAIRLY WIDESPREAD RAIN. THE LARGER EVENT GETS GOING LATER IN THE DAY AS A SECONDARY SURFACE LOW BEGINS TO DEVELOP. MODELS ARE DIFFERING A BIT WITH THE DETAILS AS THE GFS KEEPS THE SURFACE LOW FURTHER EAST AND THE EURO TAKES IT WEST OF US OVER VERMONT. GIVEN THE WESTWARD EXTENT OF THE UPPER LEVEL LOW...THE EXPECTATION IS THAT THE EURO HAS A BETTER HANDLE ON THE SURFACE LOW. THE CURRENT TRACK WOULD TAKE IT WEST OF US AND KEEP ALL OF NORTHERN NEW ENGLAND IN THE WARM SECTOR OF THE STORM. THE SYSTEM LOOKS LIKE IT COULD GENERATE A LARGE AMOUNT OF PRECIPITATION...WITH MOST OF IT IN THE FORM OF RAIN FOR THURSDAY. AS THE STORM WINDS UP IT WILL LIKELY PRODUCE SOME STRONG WINDS AS WELL.
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&& .AVIATION /20Z THURSDAY THROUGH TUESDAY/...
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SHORT TERM...AREAS OF MVFR CIGS WILL CONTINUE INTO THE OVERNIGHT...GRADUALLY LIFTING AND SCATTERING OUT TO VFR. THE EXCEPTION WILL BE NW FACING HIGHER TERRAIN...WHERE UPSLOPE FLOW WILL KEEP MVFR CIGS LOCKED IN PLACE INTO FRI. IN ADDITION...SCT IFR CONDITIONS ARE POSSIBLE INVOF KHIE WHERE SHSN WILL CONTINUE IN THE UPSLOPE FLOW REGIME. THESE SHSN TAPER OFF EARLY FRI...AND VFR CONDITIONS PREVAIL AT ALL TERMINALS FOR THE REMAINDER OF THE PERIOD. LONG TERM...PRIMARILY VFR CONDITIONS OVER THE REGION. ONSHORE FLOW LATE SUNDAY INTO TUESDAY COULD PRODUCE SOME IFR CIGS AND REDUCED VISIBILITY IN OCEAN EFFECT SNOW SHOWERS.
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&& .MARINE...
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SHORT TERM...SCA CONDITIONS WILL CONTINUE INTO FRI MORNING. WIND GUSTS NEAR 25 KTS AND SEAS AROUND 5 FT ON THE OUTER WATERS WILL GRADUALLY SUBSIDE EARLY FRI. LONG TERM...WILL LIKELY NEED FLAGS OVER THE WATERS TUESDAY NIGHT AND THEN THROUGH THURSDAY.
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&& .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST FRIDAY FOR ANZ150>154.
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&& $$ NEAR TERM...LEGRO SHORT TERM...LEGRO LONG TERM...POHL AVIATION...LEGRO/POHL MARINE...LEGRO/POHL

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