Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 021315 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 915 AM EDT SAT MAY 2 2015 .SYNOPSIS... HIGH PRESSURE BUILDS ACROSS THE REGION TODAY AND WILL SHIFT OFFSHORE ON SUNDAY...ALLOWING A WARMING TREND FOR THE WEEKEND INTO EARLY NEXT WEEK. A COLD FRONT WILL WILL CROSS THE REGION MONDAY NIGHT AND TUESDAY. HIGH PRESSURE BUILDS OVER THE REGION FOR WEDNESDAY AND THURSDAY. && .NEAR TERM /TODAY/...
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915AM UPDATE... HAVE UPDATED THE FORECAST MAINLY TO ADJUST SKY COVER FORECAST. MORNING SOUNDING INDICATED LOW CLOUD LAYER WAS ONLY ABOUT 200 FEET THICK AND VISIBLE SATELLITE (AND A VIEW OUT THE WINDOW) HAS SHOWN THE RAPID ERODING OF THIS CLOUD LAYER THIS MORNING. REMAINING LOW CLOUDS OVER LAND AREAS WILL LIKELY BE GONE WITHIN THE HOUR. SHOULD SEE CUMULUS FORMING LATER IN THE MORNING AND A CHANCE OF AN ISOLATED SHOWER IN THE MOUNTAINS. HAVE ADJUSTED HOURLY TEMPERATURE FORECAST AS WELL TO SHOW THE SEA BREEZE HAVING AN EFFECT ON TEMPERATURES NEAR THE COASTLINE. 655 AM UPDATE... THIS UPDATE FOCUSES MAINLY ON SKY FORECAST...AND ADJUSTED CLOUD COVER BASED ON FIRST VISIBLE SATELLITE OBSERVATION OF THE DAY...WITH LOW STRATUS SETTLED IN OVER MUCH OF THE COASTAL PLAIN...AND GRADUALLY BREAKING UP BY 13-14Z...ALTHOUGH LACK OF ANY SIGNIFICANT FLOW MAY HOLD THE CLOUDS IN A LITTLE LONGER IN SOME SPOTS...SHOULD BE ENOUGH SOLAR HEATING TO BURN IT OFF MOST PLACES. TWEAKED TEMPERATURES A BIT BASED ON CURRENT OBSERVATIONS AS WELL. ORIGINAL DISCUSSION... SURFACE RIDGING SHIFT SLOWLY OFFSHORE TODAY AS 500MB RIDGE NOSES IN FROM THE WEST. ANY MORNING STRATUS ON THE COAST AND IN THE KENNEBEC AND PENOBSCOT VALLEYS WILL DISSIPATE AFTER SUNRISE...WITH MAINLY SUNNY SKIES IN THE MORNING MOST EVERYWHERE ELSE. WEAK WEST FLOW DEVELOPS AT THE SURFACE N AND W OF THE MOUNTAINS...WHICH WILL BRING SOME UPSLOPE CLOUDS TO THE MOUNTAINS. THE LACK OF ANY REAL FLOW WILL ALLOW FOR SEA BREEZE TO DEVELOP ONCE AGAIN AS WELL. IN BETWEEN WE START TO SEE A LITTLE BIT OF A VERY WEAK LEE TROUGH DEVELOPING...AND COULD SEE AN ISOLATED SHOWER OR TWO IN THE MOUNTAINS AND FOOTHILLS THIS AFTERNOON...BUT WOULD BE VERY FEW AND FAR BETWEEN AND SHORT LIVED. HIGHS TODAY RANGE FROM THE MID- UPPER 60S INLAND AREAS...TO THE MID-UPPER 50S ON THE COAST.
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&& .SHORT TERM /TONIGHT AND SUNDAY/...
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SKIES SHOULD CLEAR OUT WITH JUST SOME CIRRUS OVERHEAD. BOUNDARY LAYER FLOW PICKS UP A BIT FROM THE SW...WHICH COMBINED WITH THE WARMER WILL PREVENT TEMPERATURES FROM GETTING AS COLD AS THEY DID SATURDAY MORNING. GENERALLY IN THE UPPER 30S TO LOWER 40S. ONCE AGAIN WILL LIKELY SEE SOME LOW STRATUS DEVELOPING ALONG THE COAST AND ON THE COASTAL PLAIN...BUT HOW MUCH AND WHERE STILL REMAIN UNCERTAIN...ALTHOUGH SOME OF THE MESOSCALE MODELS...PARTICULARLY THE NAM DNG5 AND THE CMC REG SUGGEST THE SAME AREA AS THIS MORNING...CASCO BAY AND POINTS EAST. A WEAK 500MB WAVE MOVES THRU THE RIDGE ALOFT ON SUNDAY...AND WITH SOME MODEST MID LEVEL WARM ADVECTION...INCREASING LOW LEVEL MOISTURE...COULD SEE A FEW ISOLATED SHOWERS...OR EVEN A THUNDERSTORM...DEVELOP IN THE AFTERNOON. THE SEA BREEZE WILL KICK IN ONCE AGAIN...AND THE BOUNDARY COULD BE THE FOCUS FOR THE CONVECTION AS WELL. AGAIN...THIS IS MORE ISOLATED IN NATURE AT THE MOMENT...BUT CANNOT RULE OUT A SHOWER OR THUNDERSTORM AWAY FROM THE COAST INTO THE MOUNTAINS. HIGHS WILL CREEP UP A FEW DEGREES EVERYWHERE COMPARED TO SATURDAY...70 TO 75 INLAND AND IN THE 60S NEAR THE COAST.
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&& .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... BY SUNDAY WE ARE UNDER THE INFLUENCE OF AN UPPER LEVEL RIDGE. THIS WILL LEAD TO WARM SOUTHWESTERLY FLOW. SEA BREEZE WILL BE LIMITED TO PENOBSCOT BAY REGION AS FURTHER SOUTH SEES FLOW OVER THE LAND. TEMPERATURES WILL WARM TO NEAR 70S. MONDAY WILL BE THE WARMEST DAY YET WITH HIGH TEMPERATURES APPROACHING 80 IN INTERIOR SOUTHERN NEW HAMPSHIRE. THE STRONG SOUTHERLY WARMING FLOW WILL COME TO AN END OVERNIGHT MONDAY INTO TUESDAY AS A COLD FRONT APPROACHES THE REGION FROM THE NORTHWEST. THE FRONT WILL CROSS IN THE EARLY MORNING HOURS OF TUESDAY. WITH SOME HINTS OF INSTABILITY AND K INDEX REACHING 30 A FEW RUMBLES OF THUNDER ARE POSSIBLE EVEN WITH THE LACK OF DIURNAL HEATING. SHOWERS WILL QUICKLY MOVE OUT TUESDAY MORNING AS THE FRONT MOVES OFF SHORE. HIGH PRESSURE WILL ONCE AGAIN BUILD INTO THE REGION FOR THE REST OF THE WEEK. THIS WILL KEEP SKIES MOSTLY SUNNY WITH TEMPERATURES IN THE MID 70S AND LOWS IN THE 40S. && .AVIATION /13Z SATURDAY THROUGH WEDNESDAY/...
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SHORT TERM...EXPECT VFR INTO THIS EVENING. WILL BE WATCHING FOR THE RETURN OF THE LOW STRATUS AGAIN TONIGHT IN THE SAME PLACES WE SAW IT THIS MORNING. VFR ON SUNDAY. LONG TERM...VFR CONDITIONS EXCEPT BRIEFLY MVFR IN ANY SCATTERED SHOWERS OR THUNDERSTORMS MONDAY AFTERNOON AND EVENING.
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&& .MARINE...
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SHORT TERM...SEAS/WINDS STAY SAFELY BELOW SCA CRITERIA TODAY THROUGH SUNDAY. ONSHORE WINDS DUE TO SEA BREEZE CIRCULATIONS DEVELOP EACH AFTERNOON. LONG TERM...WINDS/SEAS TO REMAIN BELOW SCA CONDITIONS. SOUTHWESTERLY FLOW AHEAD OF THE COLD FRONT WILL INCREASE WINDS TO AROUND 15 TO 20KTS FOR MONDAY AFTERNOON.
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&& .FIRE WEATHER...
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MODERATE MIN RH VALUES EXPECTED THIS AFTERNOON WITH GOOD RECOVERY TONIGHT. SUNDAY AND MONDAY WILL SEE AFTERNOON RH DROP TO 35-45 PERCENT WITH GOOD RECOVERY EACH NIGHT. WINDS WILL REMAIN LIGHT...10 MPH OR LESS...WITH NOTHING MORE THAN AN ISOLATED SHOWER POSSIBLE ON SUNDAY.
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&& .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ NEAR TERM UPDATE... KIMBLE

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