Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 070422 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 1222 AM EDT TUE JUL 7 2015 .SYNOPSIS... HIGH PRESSURE WILL SLIDE OFFSHORE OVERNIGHT. A RETURN FLOW BEHIND THE HIGH WILL TRANSPORT WARMER AND MORE HUMID AIR INTO THE AREA TUESDAY. A COLD FRONT WILL BRING A CHANCE OF SHOWERS AND THUNDERSTORMS MIDWEEK. HIGH PRESSURE FOLLOWS FOR THURSDAY INTO THE UPCOMING WEEKEND AS THE FRONT REMAINS STATIONARY AND IN CLOSE PROXIMITY JUST SOUTH OF NEW ENGLAND. WEAK DISTURBANCES ALOFT WILL ALLOW FOR PARTY SUNNY CONDITIONS FRIDAY AND THROUGH THE WEEKEND...MAINLY DURING THE AFTERNOON HOURS. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 1215 AM...MINOR ESTF UPDATE TO REFLECT THE CURRENT MESONET IN FIRST PERIOD GRIDS. PREV DISC... 855 PM UPDATE: INPUT LATEST MESONET DATA. ANOTHER VERY QUIET NIGHT WITH HIGH PRESSURE SLOWLY MOVING OFF COAST...SKIES REMAIN MOSTLY CLEAR. NO CHANGES TO PREVIOUS FORECAST AT THIS TIME. PREVIOUS DISCUSSION: SUNNY SKIES AND A DRY ATMOSPHERIC COLUMN RESULTED IN A QUICK WARM UP THIS MORNING WITH MANY SITES WARMING INTO THE UPPER 70S BY 10 AM. THEREAFTER WE HAVE ONLY WARMED A FEW MORE DEGREES IN MOST CASES INTO THE LOWER 80S. PORTLAND REPORTED A SEA BREEZE JUST AFTER 10 AM SO THE WARM READINGS ALONG THE COAST MAY HAD ALREADY PEAKED BY THAT TIME. OTHERWISE THE LITTLE MOISTURE THAT WAS AVAILABLE CONTRIBUTED TO A CUMULUS FIELD OVER THE REGION. EXPECTED CU TO DISSIPATE WITH THE LOSS OF DAYTIME HEATING AFTER SUNSET. TEMPERATURES SHOULD DROP QUICKLY WITH OVERNIGHT LOWS IN THE MID TO UPPER 50S NORTH AND EAST TO LOWER 60S SOUTH AND WEST. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 AM WEDNESDAY/... OVERNIGHT A WARM FRONT NEARS THE AREA FROM THE SW DRAWING MOISTURE NORTH AHEAD OF IT. SHOWERS SHOULD BEGIN SOMETIME AFTER DAYBREAK IN NH AND MOVE INTO MAINE THEREAFTER. EXPECTING THUNDERSTORMS AS WELL WITH SURFACE BASED CAPE INCREASING BY AFTERNOON. SHEAR IS NOT THAT GOOD BUT IS ENOUGH THAT WE MIGHT GET SOME STORM ORGANIZATION. STILL NOT EXPECTING ANYTHING OTHER THAN MULTICELL CLUSTERS WITH MODERATE RAINFALL AND GUSTY WINDS. A FEW OF THESE MAY PULSE UP TO STRONGER STORMS FOR A FEW MINUTES AT A TIME... BUT STILL THINKING SUB SEVERE. MODELS SHOW A BREAK IN PRECIPITATION... BETWEEN A PRE FRONTAL TROUGH AND THE COLD FRONT. ADDITIONALLY SEVERAL PIECES OF GUIDANCE HAS SPED UP FRONTAL PROGRESSION AND SHOW IT CLEARING THE COAST BY 12Z. THIS SEEMS UNREALISTIC AND BASED ON TERRAIN AND PATTERN RECOGNITION BELIEVE THIS WILL BE CLOSER TO 15-17Z. WE WILL SEE SHOWERS AND ISOLATED THUNDERSTORMS IN THE EARLY MORNING HOURS. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... A SLOW MOVING COLD FRONT WILL SLIP OFF THE COAST WEDNESDAY. THERE WILL BE SOME CLOUDINESS AND WIDELY SCATTERED SHOWERS IN ASSOCIATION WITH THIS FEATURE. THERE IS SOME SLIGHT DISAGREEMENTAS TO HOW FAR OFF THE COAST THE FRONT WILL SETTLE BY LATE IN THE DAY WEDNESDAY WHICH HAS RAMIFICATIONS TO THE FORECAST DOWN THE ROAD. THE CANADIAN MODEL IS THE MOST AGGRESSIVE PUSHING THE FRONT TO OUR SOUTH AND ALLOWING DRY AIR WITH HIGH PRESSURE TO BUILD OVER THE REGION BY THURSDAY MORNING. THE GFS...EURO AND ENSEMBLES ARE A LITTLE FURTHER NORTH WITH THIS FEATURE. IN ANY CASE...THERE IS A FAIR AMOUNT OF UNCERTAINTY TO THIS FORECAST. CYCLONIC COLD POOLS ALOFT WILL CONTINUE TO ALLOW FOR CLEAR SKIES FIRST THING IN THE MORNING FRIDAY...FOLLOWED BY A BUILD UP OF CU FIELDS AND A FEW WIDELY SCATTERED DIURNALLY DRIVEN SHOWERS. THIS WILL BE FOLLOWED BY PATCHY FOG FORMING DURING THE COOL...MOIST OVERNIGHT HOURS. SIMILAR CONDITIONS WILL FOLLOW ON SATURDAY AND SUNDAY. && .AVIATION /04Z TUESDAY THROUGH SATURDAY/... SHORT TERM...MAINLY VFR THRU TONIGHT...EXCEPT FOR SOME ADVECTION FOG NEAR AUGUSTA AND PATCHY RADIATION FOG IN MOUNTAIN VALLEYS. SCT MVFR CONDITIONS TUESDAY LATE MORNING THROUGH THE EVENING IN SHRA AND TSRA. LONG TERM...LOCALIZED IFR CONDITIONS IN CLOSE PROXIMITY TO THE FRONT WEDNESDAY MORNING WILL BE IMPROVING TO VFR AS THE FRONT MOVES OFF THE COASTLINE. OTHERWISE...CONDITIONS WILL BE MAINLY VFR. && .MARINE... SHORT TERM...WINDS AND SEAS WILL REMAIN WELL BELOW SCA LEVELS THROUGH TUESDAY AS HIGH PRESSURE STAYS OVER THE WATERS. SEAS MAY BARELY REACH 5 FT AND TOUCH 20 KTS LATE TUESDAY NIGHT AS A COLD FRONT ENTERS NORTHERN NEW ENGLAND. LONG TERM...WINDS AND SEAS WILL CONTINUE TO REMAIN BELOW SCA THRESHOLDS WITH THE EXCEPTION OF WEDNESDAY. A SOUTHERLY FLOW WILL SWITCH TO THE NORTHWEST DURING THE DAY WEDNESDAY...HOWEVER LINGERING SWELLS WILL BE REACHING THE COAST DURING THE MIDWEEK PERIOD. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ ES

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