Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 291333 AAA AFDGYX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAY ME 933 AM EDT FRI APR 29 2016 .SYNOPSIS... DRY AIR AND SURFACE HIGH PRESSURE PERSISTS INTO SATURDAY...AS A SERIES OF WEAK DISTURBANCES PASS TO OUR SOUTH. LOW PRESSURE TRACKING SOUTH OF THE AREA LATE SUNDAY INTO MONDAY WILL BRING THE NEXT CHANCE OF PRECIPITATION...WHICH WILL BE MAINLY RAIN. WEAK HIGH PRESSURE BUILDS IN FOR TUESDAY...WITH ANOTHER LOW PASSING OFFSHORE MID TO LATE NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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UPDATE...A FEW CHANGES TO THE CURRENT FORECAST BASED ON LATEST OBSERVATIONAL TRENDS AND MESOSCALE MODEL GUIDANCE. ONSHORE FLOW AND MODEST MOISTURE ACROSS SRN ZONES IS ALLOWING MARINE STRATUS TO FORM. THIS IS ESPECIALLY THE CASE ACROSS COASTAL SWRN ME AND SEACOAST NH...WHERE FRICTIONAL CONVERGENCE IS LIKELY ENHANCING LIFT ENOUGH TO EXPAND CLOUD COVER. IN ADDITION...FORECAST SOUNDINGS SHOW DEEP ENOUGH CLOUD TO SUPPORT SOME PRECIP. OVERALL THE ATMOSPHERE IS STILL QUITE DRY...SO WILL INCLUDE SPRINKLES FOR COASTAL ZONES...BUT DO NOT EXPECT ANY SHOWERS TO BE HEAVY ENOUGH TO WET THE GROUND. PREV DISC... AT 06Z...A NORTHWEST TO SOUTHEAST ORIENTED RIDGE OF HIGH PRESSURE REMAINED DRAPED ACROSS THE FORECAST AREA. GOES INFRARED IMAGERY SHOWED HIGH AND PATCHY MID CLOUDS ACROSS THE SOUTHERN HALF OF NEW HAMPSHIRE AND ADJACENT SOUTHWEST MAINE. FOR TODAY...LITTLE CHANGE IS EXPECTED WITH THE BRIGHTEST SKIES ACROSS NORTHERN NEW HAMPSHIRE AND THE MAINE MOUNTAINS AND FOOTHILLS AND FILTERED SUNSHINE THROUGH HIGH CLOUDS FURTHER SOUTH. HIGHS WILL BE MAINLY IN THE 50S WITH THE COOLEST READINGS ACROSS THE MOUNTAINS...AND ALONG THE COAST AS THE LIGHT SYNOPTIC FLOW QUICKLY TURNS ONSHORE.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... LITTLE CHANGE TONIGHT AND SATURDAY AS THE RIDGE OF HIGH PRESSURE AND DRY AIR REMAINS DRAPED ACROSS THE FORECAST AREA. CLOUDS WILL BRIEFLY THICKEN EARLY TONIGHT OVER THE SOUTHERN HALF OF NEW HAMPSHIRE INTO ADJACENT SOUTHWEST MAINE AS A SHORTWAVE IMPULSE RACES ACROSS THE REGION. LOWS TONIGHT WILL RANGE FROM THE 20S ACROSS NORTHERN AND MOUNTAIN SECTIONS WHERE CLOUD COVER WILL BE MINIMAL TO THE 30S ELSEWHERE. IT`LL BE SEVERAL DEGREES WARMER ON SATURDAY AS 850 MILLIBAR TEMPERATURES BEGIN TO MODERATE. SIMILAR TO TODAY...THE COOLEST TEMPERATURES WILL BE FOUND OVER MOUNTAIN SECTIONS...AND ALONG THE COAST AS LIGHT SYNOPTIC FLOW TURNS ONSHORE. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... HIGH IMPACT WX: NONE. 500 MB PATTERN WILL REMAIN WELL AMPLIFIED AND BLOCKY THROUGH THE EXTENDED...ALBEIT WITH A BRIEF BREAK DOWN OF THE BLOCKING OVER THE WEEKEND INTO EARLY NEXT WEEK...BEFORE A WELL AMPLIFIED TROUGH TRIED TO FORM INTO THE GREAT LAKES AND OH/TN VLYS. THIS WILL LEAD TO AN UNSETTLED...AND LOW CONFIDENCE...FORECAST PERIOD STARTING SUNDAY AND EXTENDING INTO LATE NEXT WEEK. MODELS DO SHOW BETTER LARGE SCALE AGREEMENT FOR SUNDAY AND MONDAY AS SHALLOW BUT POTENT 500MB WAVE TRACKS THRU THE GREAT LAKES AND ACROSS NEW ENGLAND. PRECIP SHOULD HOLD OFF THROUGH SAT NIGHT AND MAY STRUGGLE TO MAKE ITS WAY OUT OF THE CT VLY ON SUNDAY AS DRY AIR MASS IN PLACE...AND THE FACT THAT MID-LVL WAA MOVES INTO WEAK RIDGING AT 500 MB. DEVELOPING ONSHORE COULD PRODUCE SOME DRIZZLE ON THE COASTAL PLAIN LATE IN THE DAY AS WELL. BEST CHANCE OF PRECIP WILL BE SUNDAY NIGHT AND MONDAY AS THE SFC LOW DEVELOPS OVER THE MID-ATLANTIC AND TRACKS JUST OUTSIDE THE 40/70 BENCHMARK. GFS. WHILE BOTH MODELS PRODUCE A SIMILAR TRACK...GFS MORE AGGRESSIVE WITH DEEPENING THE SFC LOW AND HAS MORE QPF...BUT NEITHER MODELS PRODUCES A SOAKER...GENERALLY HALF TO AS MUCH A 0.75 INCHES IN THE GFS. LEANED MORE TOWARD THE EURO AND ITS OVERALL BETTER PERFORMANCE. SINCE THERE IS SOME COLD AIR BEING PULLED SOUTH AND BEING GENERATED BY PRECIP PROCESS...HAVE TO TALK ABOUT SNOW...BIT THIS SYSTEM IS WARMER THAN THE PREVIOUS SYSTEM FORM TUESDAY...AND 850 TEMPS GENERALLY STAY ABOVE -2C /COMPARED TO -4 OR -5 LAST TUESDAY/...AND THIS WILL BE MAINLY IN THE NRN ZONES. THE HIGHER TERRAIN IN THE MOUNTAINS COULD SEE SOME ACCUMULATING SNOW ON MONDAY...BUT EVERYWHERE ELSE SHOULD SEE SOME RAIN. THE SFC LOW WILL TRACK OUT TO THE NE QUICKLY BY TUE MORNING AND TUE-WED LOOK MAINLY DRY IN THE EURO...AS HIGH PRESSURE BUILDS TO OUR SOUTH. BY THURSDAY COULD SEE ANOTHER COASTAL LOW BRING SOME RAIN TO THE REGION...BUT CONFIDENCE IS LOW. TEMPS THRU THE PERIOD WILL BE RUNNING A LITTLE BELOW NORMAL...BUT THE COOLEST DAYS WILL BE SUNDAY AND MONDAY WITH HIGHS SUNDAY AROUND 50...AND MONDAY WILL BE IN THE 40S TO MAYBE 50. OVERALL THOUGH...SHOULD SEE A VERY GRADUAL WARMING TREND MID-LATE WEEK. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... SHORT TERM /THROUGH SATURDAY/...LCL MVFR PSBL THIS AM IN CEILINGS...OTW VFR CONDITIONS EXPECTED THROUGH THE PERIOD. LONG TERM...MAINLY VFR SAT NIGHT INTO SUNDAY MORNING...WITH SOME MVFR POSSIBLE SUN AFTERNOON. EXTENDED PERIOD OF FLIGHT RESTRICTIONS /PROBABLE IFR OR LOWER SUNDAY NIGHT INTO MONDAY/ IN RA AND DZ AND LOW CIGS. IMPROVEMENT TO MVFR MON NIGHT AND VFR TUE. && .MARINE... SHORT TERM /THROUGH SATURDAY/...WINDS AND SEAS WILL REMAIN RELATIVELY LIGHT THROUGH THE PERIOD...THEREFORE NO SCAS ARE EXPECTED. WINDS ARE EXPECTED TO BECOME LOCALLY ONSHORE DURING THE AFTERNOON HOURS. LONG TERM...MAY NEED SCA FOR BOTH WINDS/SEAS MONDAY AND MON NIGHT. && .FIRE WEATHER... AN ONSHORE WIND WILL RESULT IN MINIMUM RELATIVE HUMIDITY VALUES IN THE 30S AND 40S ACROSS SOUTHERN NEW HAMPSHIRE AND THE MAINE COASTAL PLAIN. ACROSS NORTHERN NEW HAMPSHIRE AND THE WESTERN MAINE MOUNTAINS AND FOOTHILLS...MINIMUM RELATIVE HUMIDITIES WILL RANGE FROM 20 TO 30 PERCENT BUT WITH LIGHT WINDS. SIMILAR RELATIVE HUMIDITY VALUES ALONG WITH LIGHT WINDS ARE EXPECTED SATURDAY. GOOD RELATIVE HUMIDITY RECOVERY WILL OCCUR TONIGHT. A WIDESPREAD PRECIPITATION EVENT IS LIKELY FOR LATE SUNDAY AND MONDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ NEAR TERM...LEGRO

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