Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 192159 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 559 PM EDT TUE MAY 19 2015 .SYNOPSIS... A COLD FRONT WILL PASS ACROSS THE REGION TONIGHT ALLOWING FOR A DRIER AIR MASS TO BUILD IN. HIGH PRESSURE WILL CONTINUE TO BUILD IN THROUGH WEDNESDAY NIGHT. LOW PRESSURE WILL PASS WELL TO OUR SOUTH THURSDAY NIGHT INTO FRIDAY...WITH ANOTHER COLD FRONT SWINGING ACROSS THE REGION DURING THE DAY ON FRIDAY. HIGHER PRESSURE THEN BUILDS IN OVER THE WEEKEND. ANOTHER COLD FRONT LOOKS TO PUSH INTO THE AREA EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
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UPDATE...QUICK UPDATE TO TWEAK POPS CLOUDS AND TEMP/DEWPTS. MOST AREAS ARE AND WILL REMAIN RAIN FREE THIS EVENING SO HAVE TRIED TO LOWER POPS IN GENERAL AND RAISE POPS IN AREAS WHERE SHOWERS/THUNDER ARE OCCURRING. ISOLATED CELLS ARE MOVING THROUGH NORTHERN NH AND NW MAINE AS WELL AS CENTRAL GRAFTON COUNTY. THESE WILL CONTINUE TREKING EAST. MEANWHILE FOG AND STRATUS CONTINUE TO MOVE INTO THE MID COAST. EXPECT THIS TO SPREAD DOWN THE COAST BEFORE FINALLY GETTING PUSHED BACK OFFSHORE AFTER FRONTAL PASSAGE LATE TONIGHT. PREV DISC...SHOWERS AND THUNDERSTORMS DEVELOPING ACROSS UPSTATE NY AND VT WILL PUSH ACROSS OUR REGION LATE THIS AFTERNOON AND EVENING...MAINLY BETWEEN 4 PM AND 9 PM. THE BEST INSTABILITY WILL BE ACROSS WESTERN AND NORTHERN NH WHERE SOME SUNSHINE HAS ALLOWED FOR SOME MODEST HEATING. THE RESULT SHOULD BE UP TO 1000 JOULES OF CAPE JUXTAPOSED WITH AROUND 35 KT OF DEEP LAYER SHEAR. THIS SHOULD BE SUFFICIENT FOR A COUPLE OF LOCALLY STRONG THUNDERSTORMS...WITH AN ISOLATED SEVERE ONE OR TWO POSSIBLE. MORE STABLE AIR ON THE COASTAL PLAIN WILL MITIGATE THE THREAT...BUT A FEW STORMS MAY EVEN MAKE IT THERE EARLY THIS EVENING. STRONG SFC WIND GUSTS AND MARGINALLY SEVERE HAIL WILL BE THE MAIN THREATS...ALONG WITH THE USUAL ATTENDANT THREAT FOR LOCALLY HEAVY DOWNPOURS AND FREQUENT LIGHTNING. FOG MAY ONCE AGAIN DEVELOP ON THE COAST THIS EVENING PRIOR TO THE COLD FRONTAL PASSAGE. THE FRONT WILL SWEEP THE SOUPIER AIR MASS OFFSHORE AFTER MIDNIGHT...ALLOWING FOR MUCH DRIER AIR TO WORK IN.
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&& .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... A MUCH DRIER AIRMASS WILL MOVE IN ON WEDNESDAY ON GUSTY NW WINDS. WINDS COULD POTENTIAL GUST UP TO 30 MPH. HIGHS WILL BE IN THE 60S AND NO PRECIPITATION IS EXPECTED. HOWEVER...SUNSHINE WILL PROBABLY BE REPLACED BY DEVELOPING STRATOCU LATE MORNING THRU AFTERNOON. WINDS SHOULD DIMINISH AND SKIES SHOULD CLEAR WEDNESDAY EVENING. A CHILLY NIGHT WILL BE IN STORE...WITH THE BETTER RADIATORS HEADING DOWN INTO THE 30S. A FROST WILL BE POSSIBLE IN THESE AREAS. && .LONG TERM /THURSDAY THROUGH TUESDAY/... THE MODELS ARE IN GENERAL AGREEMENT ON THE LONG WAVE PATTERN THROUGH LATE NEXT WEEK OVER THE EASTERN HALF OF THE CONUS. WE BEGIN THE PERIOD WITH AN UPPER TROUGH OVER THE GREAT LAKES AND NEW ENGLAND. A SERIES OF SHORTWAVE IMPULSES WILL ROTATE AROUND THIS TROUGH WITH SEVERAL MOISTURE STARVED TROUGHS OR WEAK COLD FRONTS TO DROP SOUTH ACROSS THE AREA. ON SATURDAY...THE TROUGH LIFTS OUT AND WE`RE LEFT WITH FLAT RIDGING AND SURFACE HIGH PRESSURE BUILDING BY TO OUR SOUTH. THE NEXT SHORTWAVE PASSES TO OUR NORTH LATE SUNDAY AND DRIVES A COLD FRONT SOUTHWARD INTO THE AREA TO END THE WEEKEND ACCOMPANIED BY WIDELY SCATTERED CONVECTION. THE SURFACE FRONT SHOULD STALL TO OUR SOUTH ON MONDAY...WITH SURFACE RIDGE PROVIDING A DRY HOLIDAY FOR OUR AREA. HOWEVER...OVER THE PAST 24 HOURS MODEL DIFFERENCES HAVE EMERGED WITH ECMWF SIMILAR TO YESTERDAY`S SOLUTION...WHILE GFS RETURNS THE FRONT BACK NORTH WITH INCREASING CLOUDS AND OVERRUNNING SHOWERS AND THUNDERSTORMS ARRIVING BY MONDAY AFTERNOON. && .AVIATION /22Z TUESDAY THROUGH SUNDAY/... SHORT TERM...IFR OR LOWER CONDITIONS IN LOW STRATUS AND FOG THIS EVENING...MAINLY AT THE COAST...WILL GIVE WAY TO RAPIDLY DEVELOPING VFR CONDITIONS AFTER MIDNIGHT AS A COLD FRONT MOVES THROUGH. VFR WITH GUSTY NWLY SFC WINDS LIKELY FOR WEDNESDAY. VFR WITH DIMINISHED WINDS WEDNESDAY NIGHT. SCT THUNDERSTORMS POSSIBLE 20Z THRU 02Z THIS AFTERNOON/EVENING. LONG TERM.... FRI AND SUN...SCT MVFR PSBL IN SHOWERS AND TSTMS. && .MARINE... SHORT TERM...SCA IN EFFECT FOR WEDNESDAY WITH NWLY WINDS GUSTING AROUND 25 KT. THE MORE FREQUENT GUSTINESS SHOULD BE NEAR-SHORE WHERE MIXING WILL BE BEST. SEAS SHOULD REMAIN A0B 5 FT HOWEVER. LONG TERM... THU NIGHT - SUN...SMALL CRAFT WINDS AND SEAS ARE POSSIBLE. && .FIRE WEATHER... MUCH DRIER CONDITIONS ARE EXPECTED WEDNESDAY AND THURSDAY. FIRE SPREAD POTENTIAL MAY BE HIGH ACROSS SRN NH WHERE MIN RH VALUES DROP INTO THE 20S WEDNESDAY COUPLED WITH 25 KT WIND GUSTS. LIGHTER WINDS AND EXPECTED THURSDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 AM TO 7 PM EDT WEDNESDAY FOR ANZ150>154. && $$ UPDATE...TFH

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