Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 270150 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 950 PM EDT SUN APR 26 2015 .SYNOPSIS... THE PERSISTENT UPPER LEVEL LOW OVER THE CANADIAN MARITIMES WILL SHIFT SW INTO THE GULF MAINE ON MONDAY AND THIS WILL PROVIDE US WITH MORE NUMEROUS SHOWERS. THE LOW WILL FINALLY 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 AM MONDAY MORNING/... 950 PM...THIS IS A MINOR ESTF UPDATE TO REFLECT THE CURRENT MESONET IN FIRST PERIOD GRIDS. PREV DISC... 615 PM...MINOR ESTF UPDATE TO INGEST THE LATEST MESONET INTO FIRST PERIOD GRIDS. PREV DISC... THE PERSISTENT 500 MB CLOSE LOW OVER THE MARITIMES PICKS UP A DECENT WAVE FROM THE SRN STREAM TONIGHT AND ROTATES THE WAVE AROUND THE LOW AND BACK INTO NRN NEW ENGLAND ON MONDAY...ALLOWING THE WRN LOBE OF THE LOW TO DEEPEN AND PULLING THE WHOLE SYSTEM BACK TO THE SW TOWARDS THE GULF OF ME. FOR TONIGHT...AS ONE WEAK WAVE WAVE EXITS SE...SHOULD SEE ANY OF THE LIGHT SHRA WIND DOWN AROUND SUNSET...AS THESE SHOWERS SEEM TO BE POPPING UP IN AREAS WITH SOME BREAK OF SUN...AND ARE INSTABILITY DRIVEN. HOWEVER AS THE ENERGY BEGINS TO CREST THE POLEWARD SIDE OF THE 500MB LOW FROM THE NE WILL START TO SEE SHRA MOVE INTO ERN ZONES AROUND OR AFTER MIDNIGHT. TEMPS FALL BACK INTO THE 30S TO AROUND 40 AGAIN. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... AS THE MORE POTENT 500MB WAVE PULLS THE LOW BACK TO THE SOUTH AND EAST WILL SEE SOME BETTER DYNAMICS AND SOME THERMAL CIRCULATIONS DEVELOP...WHICH WILL MEAN THE BEST CHANCE FOR SHOWERS IN THE CWA SINCE THIS LOW MOVED IN ON THURSDAY. IT IS NOT LKLY TO RAIN ALL DAY...BUT THE THREAT OF SHOWERS WILL BE THERE...WITH THE BEST CHANCE MON AFTERNOON INTO EARLY EVE. OVERALL QPF WILL NOT BE SIGNIFICANT GENERALLY AROUND ONE TO TWO TENTHS OF AN INCH AT BEST. ONCE AGAIN MAXES WILL BE STUCK IN THE 50S MOST PLACES. SHRA LINGER MON EVE...BUT SHOULD DIMINISH LATER IN THE NIGHT WITH SOME PARTIAL CLEARING LATE. LOWS DROP INTO THE 30S TO AROUND 40 ONCE AGAIN. && .LONG TERM /TUESDAY THROUGH SUNDAY/... THE WEEK BEGINS WITH A CLOSED UPPER LEVEL LOW IN PLACE OVER THE MARITIMES AND NORTHWESTERLY FLOW BRINGING AFTERNOON SHOWERS INTO NORTHERN NEW ENGLAND. THIS CLOSE LOW WILL BEGIN TO MOVE EAST ON TUESDAY... ALLOWING FOR A RIDGE TO BUILD IN FOR THE MIDDLE OF THE WEEK. BY WEDNESDAY SHOWERS WILL EXIT TO FAR EASTERN MAINE. WEDNESDAY INTO THURSDAY WILL BE MOSTLY SUNNY WITH WARMING TEMPERATURES. FRIDAY A SPLIT JET STREAM DEVELOPS WITH A SOUTHERN BRANCH DIPPING SOUTHWARDS TO NEAR GEORGIA AND THEN RETURNING NORTHWARDS UP THE EASTERN SEABOARD. THIS SETS US UP FOR A CLASSIC COASTAL LOW TRACK... AND INDEED SOME MODELS WOULD LIKE TO BRING A STRONG COASTAL LOW UP THROUGH THE 70W/40N BENCHMARK AS EARLY AS SATURDAY MORNING. THIS IS A VERY LOW CONFIDENCE SCENARIO. CURRENTLY THE CLOSED LOW OVER NEW BRUNSWICK IS PARTIALLY BLOCKED BY HIGH PRESSURE BUILT IN OVER LABRADOR... MEANING THE CLOSED LOW MAY TAKE LONGER TO MOVE OUT THAN ANTICIPATED. WITH OVER 5 DAYS TO GO...WILL LEAVE IT AT A BLEND OF MODEL GUIDANCE AND NOTE THAT THE WIDELY VARYING OPTIONS WILL AVERAGE OUT TO A CHANCE OF SHOWERS FOR NOW. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... SHORT TERM...DESPITE SHRA WILL SEE VFR VARYING TO MVFR AT TIMES TONIGHT THROUGH THE DAY MON. IMPROVEMENT TO VFR EXPECTED MON NIGHT. LONG TERM...GENERALLY VFR CONDITIONS EXPECTED TO PREVAIL IN THE EXTENDED. UPPER LOW PRESSURE WILL REMAIN NEARBY THRU ABOUT WEDNESDAY...SO CANNOT RULE OUT AFTERNOON MVFR CEILINGS OR VISIBILITY IN SCATTERED SHOWERS. BEYOND MIDWEEK LOW CONFIDENCE ON MVFR SHOWERS. && .MARINE... SHORT TERM...WEAK LOW PRESSURE WILL PROVIDE VERY LIGHT WINDS THROUGH MONDAY. WINDS INCREASE MON NIGHT AS SFC LOW INTENSIFIES AS IT MOVES EAST. LONG TERM...SCA CONDITIONS ARE POSSIBLE LATER IN THE WORK WEEK DEPENDING ON HOW CLOSE TO THE GULF OF MAINE LOW PRESSURE TRACKS. && .FIRE WEATHER... COOL AND MOIST CONDITIONS CONTINUE THROUGH THE EARLY WEEK PERIOD WITH LIGHT WINDS. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ ES

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