Area Forecast Discussion
Issued by NWS Portland, ME

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491 FXUS61 KGYX 211627 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 1227 PM EDT THU MAY 21 2015 .SYNOPSIS... HIGH PRESSURE WILL BUILD OFFSHORE TODAY. AN AREA OF LOW PRESSURE WILL PASS WELL TO OUR SOUTH TONIGHT AND FRIDAY. A COLD FRONT WILL SWING ACROSS THE REGION DURING THE DAY ON FRIDAY. HIGH PRESSURE THEN BUILDS IN OVER THE WEEKEND. ANOTHER COLD FRONT LOOKS TO CROSS THE AREA TO END THE HOLIDAY WEEKEND. && .NEAR TERM /UNTIL 8 PM THIS EVENING/...
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1225 PM...MINOR ESTF UPDATE TO INGEST THE 16Z MESONET IN 1ST PERIOD GRIDS TO BETTER REFLECT THE DEVELOPING SEABREEZE. PREV DISC... 1025 AM...MINOR ESTF UPDATE TO REFLECT CURRENT SATELLITE TRENDS AND TO INGEST THE 14Z MESONET INTO 1ST PERIOD GRIDS. PREV DISC... 0645 UPDATE...ALL STATIONS IN OUR FORECAST AREA ARE NOW ABOVE FREEZING AND WARMING. WILL BE ISSUING AN UPDATE SHORTLY TO DROP FREEZE WARNINGS AND FROST ADVISORIES. PREVIOUS DISCUSSION... HIGH PRESSURE SHOULD LEAD TO A PARTLY CLOUDY DAY ACROSS THE REGION WITH AREAS OF CIRRUS PASSING OVERHEAD. AFTER A COLD START THIS MORNING...TEMPERATURES SHOULD REBOUND QUICKLY WITH HIGHS FROM THE MID 60S IN THE MOUNTAINS TO THE LOW TO MID 70S IN SOUTHERN AREAS. WINDS WILL TURN ONSHORE IN COASTAL AREAS THIS AFTERNOON LIMITING WARMING TO THE 60S.
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&& .SHORT TERM /8 PM THIS EVENING THROUGH 6 PM FRIDAY/... A SHORT WAVE PASSING THROUGH THE AREA OVERNIGHT COMBINED WITH LOW PASSING TO THE SOUTH WILL PRODUCE HIGH AND MID LEVEL CLOUDS ACROSS THE REGION WHICH WILL LIMIT RADIATIONAL COOLING. TEMPS SHOULD REMAIN ABOVE FREEZING ALL AREAS..WITH ONLY COOS COUNTY REACHING AS LOW AS THE MID 30S. A COLD FRONT WILL BE CROSSING THE REGION FRIDAY. MODELS ARE NOT CONSISTENT WITH THE TIMING OF THE FRONT WITH THE GFS BEING A BIT FASTER. SCATTERED SHOWERS WILL ACCOMPANY THE FRONT WITH THE GREATEST THREAT OF RAIN ACROSS THE EASTERN PART OF FORECAST AREA WITH A LESSER THREAT IN NEW HAMPSHIRE. TEMPS IN THE NORTHERN MOUNTAINS WILL BE LIMITED BY THE FRONTAL PASSAGE AND MAY NOT REACH 60 DEGREES BEFORE STARTING TO COOL OFF AGAIN. SOUTH OF THE MOUNTAINS...TEMPS WILL REACH THE 60S AND 70S PRIOR TO THE FRONTAL PASSAGE. AGAIN..ONSHORE FLOW WILL LIMIT TEMPS IN COASTAL AREAS. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... THE BIGGEST STORY IN THE EXTENDED COMES EARLY IN THE PERIOD. STRONG COLD FRONT WILL MOVE THRU THE REGION...WITH SECONDARY...REINFORCING SHOT OF COLD AIR TO ARRIVE LATE FRI/EARLY SAT. TEMPS AT H8 WILL APPROACH 3 STANDARD DEVIATIONS BELOW NORMAL BY EARLY SAT...WITH H9 TEMPS 2 SD BELOW NORMAL. BASED ON MODEL FORECASTS H8 TEMPS OBSERVED AT 12Z SAT COULD BE SOME OF THE COLDEST IN THE PERIOD OF RECORD FOR THIS TIME OF YEAR. MUCH LIKE TONIGHT THE HIGH PRES WILL STILL BE BUILDING IN LATE FRI...MEANING THAT THE GRADIENT WILL NOT ALLOW WINDS TO COMPLETELY DECOUPLE EARLY ON. MAV GUIDANCE APPEARS TO BE WAY TOO COLD GIVEN A FORECAST OF BOUNDARY LAYER STAYING AT LEAST PARTIALLY MIXED. DISCOUNTED LOW 20S FORECASTS FOR THE FAR N IN FAVOR OF A MORE REASONABLE UPPER 20S TO NEAR 30 FROM THE MET. STRENGTH OF THE FLOW EVEN SUGGESTS SOME DOWNSLOPE WARMING IS POSSIBLE IN THE LEE OF THE MTNS...SO NOT READY TO BITE ON NEAR OR BELOW FREEZING RIGHT TO THE COAST JUST YET. HOWEVER IT DOES SEEM LIKELY THAT IT WILL AT LEAST BE AS COLD AS CURRENT TEMPS TONIGHT...SO ANOTHER ROUND OF FROST/FREEZE HEADLINES ARE LIKELY. IN ADDITION...UPPER LOW SWINGING ACROSS THE AREA SHOULD LEAD TO SOME MTN SHOWERS. GIVEN FORECAST TEMPS ALOFT...THOSE SHOWERS SHOULD BE OF THE FROZEN VARIETY. WE RECOVER NICELY FOR THE SECOND HALF OF THE HOLIDAY WEEKEND...WITH MILDER TEMPS EXPECTED AS A WARM FRONT LIFTS NWD THRU THE NORTHEAST. MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT THAT ANY COLD FRONT SUN WILL BE WEAKER AND JUST BRUSH THE REGION...FOLLOWED BY WARM FRONT LIFTING THRU THE AREA RATHER THAN STALLING TO THE S. THAT WILL KEEP THE THREAT FOR DIURNAL SHOWERS IN THE FORECAST EARLY NEXT WEEK. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... SHORT TERM...MAINLY VFR CONDITIONS. MVFR CONDITIONS POSSIBLE IN SCATTERED SHOWERS FRIDAY AFTERNOON. LONG TERM...VFR CONDITIONS EXPECTED TO PREVAIL THRU THE HOLIDAY WEEKEND. GUSTY WNW FLOW WILL BE IN PLACE SAT...WITH GUSTS AROUND 25 KTS POSSIBLE AT ALL TERMINALS. WEAK COLD FRONT WILL TRY TO CROSS THE AREA SUN...WITH WIDELY SCATTERED SHOWERS. WIDESPREAD VSBY OR CIG RESTRICTIONS ARE NOT EXPECTED AT THIS TIME WITH THIS FEATURE. && .MARINE... SHORT TERM...WITH SW WINDS DEVELOPING...SEAS MAY APPROACH MINIMAL SCA CRITERIA OFFSHORE TONIGHT AND EARLY FRIDAY...OTHERWISE WINDS AND SEAS BELOW SCA CRITERIA. LONG TERM...CAA BEHIND COLD FRONT FRI WILL LEAD TO A PROBABLE PERIOD OF SCA CONDITIONS ON THE WATERS SAT. THE SECOND HALF OF THE WEEKEND INTO EARLY NEXT WEEK HIGH PRES WILL BE MORE IN CONTROL...WITH WINDS AND SEAS EXPECTED TO REMAIN BELOW SCA THRESHOLDS. && .FIRE WEATHER... MOSTLY DRY CONDITIONS CONTINUE TODAY AND FRIDAY. AFTERNOON MINIMUM RELATIVE HUMIDITIES WILL RANGE FROM 20 TO 35PERCENT ACROSS SOUTHERN NEW HAMPSHIRE WITH WINDS GUSTING TO 15 TO 20 MPH. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ ES

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