Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 031022 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 622 AM EDT TUE MAY 3 2016 .SYNOPSIS... WEAK HIGH PRESSURE SPREADS OVER NORTHERN NEW ENGLAND TODAY WHILE LOW PRESSURE TRACKS OFF THE MID ATLANTIC COAST AND SOUTHEAST OF CAPE COD TONIGHT. SOME LIGHT RAIN MAY SPREAD INTO SOUTHERN NEW HAMPSHIRE TODAY AS THIS LOW MOVES BY. AN EASTERLY ONSHORE FLOW DEVELOPS ON WEDNESDAY BETWEEN LOW PRESSURE TO THE SOUTH AND HIGH PRESSURE TO THE NORTH. THIS WILL KEEP TEMPERATURES COOL WITH PLENTY OF CLOUD COVER. ANOTHER AREA OF LOW PRESSURE WILL DEVELOP AND TRACK NORTHWARD TO THE EAST OF CAPE COD ON THURSDAY AND COULD BRING ANOTHER CHANCE OF RAIN TO OUR AREA. PERSISTENT LOW PRESSURE LINGERS THROUGH THE WEEKEND KEEPING COOL TEMPERATURES AND SHOWERY WEATHER IN THE FORECAST. && .NEAR TERM /TODAY/...
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620AM UPDATE... RAIN IS SKIRTING SOUTHERN NEW HAMPSHIRE AND WILL NOT LIKELY MAKE IT MUCH FURTHER NORTH THROUGH THE MORNING. HAVE UPDATED THE FORECAST WITH LATEST OBSERVED TEMPERATURES. OTHERWISE NO CHANGES WERE NEEDED. ORIGINAL DISCUSSION... WEAK HIGH PRESSURE OVER QUEBEC AND NORTHERN NEW ENGLAND WILL KEEP WINDS LIGHT ACROSS MOST OF MAINE AND NEW HAMPSHIRE TODAY. EXPECT CLOUD COVER TO REMAIN WITH TEMPERATURES STAYING IN THE 40S TO LOW 50S FOR HIGHS. LOW PRESSURE TRACKING SOUTH OF CAPE COD MAY BRING SOME LIGHT RAIN TO FAR SOUTHERN NEW HAMPSHIRE THIS MORNING BEFORE EXITING THIS AFTERNOON. LEADING EDGE OF THIS IS MOVING THROUGH MASSACHUSETTS AND NEAR THE NEW HAMPSHIRE BORDER ALREADY EARLY THIS MORNING BUT IS NOT EXPECTED TO MAKE MUCH PROGRESS NORTHWARD.
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&& .SHORT TERM /TONIGHT AND WEDNESDAY/... LOW PRESSURE TRACKS FURTHER OUT INTO THE ATLANTIC TONIGHT WITH HIGH PRESSURE BECOMING MORE FIRMLY ESTABLISHED OVER EASTERN QUEBEC AND THE GULF OF SAINT LAWRENCE. THIS WILL BEGIN A PUSH OF EASTERLY WINDS FROM THE GULF OF MAINE AND INTO MAINE AND NEW HAMPSHIRE TONIGHT. SINCE THE GULF OF MAINE HAS NOT BEEN SCOURED OF MOISTURE... EXPECT THIS SHIFT IN WIND DIRECTION TO REINFORCE THE LOW LEVEL MOISTURE ACROSS THE AREA AND EVENTUALLY LEAD TO THICKENING CLOUDS AND FOG BY WEDNESDAY MORNING... WITH DRIZZLE POSSIBLE THROUGH THE DAY WEDNESDAY. CURRENT FORECAST HAS TEMPERATURES WARMING INTO THE 50S ON WEDNESDAY... BUT GIVEN THE ONSHORE FLOW AND WATER TEMPERATURES IN THE LOW TO MID 40S...THIS MIGHT BE TOO OPTIMISTIC. THE WARMEST AREAS WILL BE TO THE WEST OF THE MOUNTAINS WHERE THEY MAY MAKE A RUN AT 60 DEGREES. A DEVELOPING CUT OFF LOW OVER THE SOUTHERN APPALACHIANS WILL SET UP A SOUTHERLY FLOW ALOFT OVER OUR AREA. A SHORTWAVE TROUGH EMBEDDED IN THIS FLOW IS EXPECTED TO MOVE NORTHWARD INTO THE REGION WEDNESDAY AFTERNOON AND WILL INCREASE THE CHANCE OF SHOWERS. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... S/WV TROF DROPPING OUT OF THE HUDSON BAY REGION WILL HELP TO AMPLIFY AND CARVE OUT A SIGNIFICANT ERN CONUS TROF THAT WILL DOMINATE OUR WX THRU THE WEEKEND. THE DEVELOPING L/WV TROF IS NOW FORECAST TO APPROACH 4 STANDARD DEVIATIONS BELOW NORMAL HEIGHTS FOR THIS TIME OF YEAR...AND WILL HAVE A HUGE INFLUENCE ON SENSIBLE WX AS A RESULT. HERE IN THE NORTHEAST...THAT WILL PLACE US IN THE DEEP ONSHORE FLOW. SO WE/LL CONTINUE WITH COOL...CLOUDY...MOIST...AND SHOWERY CONDITIONS. THU AND FRI WILL BE MOST LIKELY TO SUFFER FROM THAT ONSHORE FLOW...AND POP IS HIGHEST FOR THESE PERIODS. AS UPPER LOW MOVES MORE OVERHEAD INTO THE WEEKEND...I FEEL THAT PRECIP COULD CHANGE TO HAVE MORE OF A DIURNAL PATTERN TO IT. MEANING SHOWERS INCREASE IN COVERAGE WITH THE HEATING OF THE DAY...AND DISSIPATE OVERNIGHT. NOT THE BEST OUTDOOR WX...BUT ALSO NOT A WASHOUT. BEYOND THE WEEKEND...ENSEMBLE GUIDANCE IS TRYING TO BUILD SOME EAST COAST RIDGING TOWARDS THE MIDDLE OF NEXT WEEK. THAT COULD BRING US A COUPLE OF DRIER AND WARMER DAYS...ESPECIALLY INLAND. HOWEVER...THE SAME GEFS AND EPS MEANS DEVELOP ANOTHER TROF UPSTREAM AND TRY AND MIGRATE IT OUR WAY YET AGAIN. THERE ARE PLENTY OF DETAILS TO WORK OUT BEFORE THEN THOUGH. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... SHORT TERM...IFR CEILINGS CONTINUE TO SHIFT EASTWARD INTO EASTERN MAINE WITH SOME BREAKS OCCURRING BEHIND IT. HOWEVER... THE BREAKS HAVE LED TO FOG DEVELOPING ESPECIALLY IN THE VALLEYS OF NEW HAMPSHIRE. THIS FOG SHOULD LIFT BETWEEN 12 AND 14Z. LOW PRESSURE TRACKING TO THE SOUTH OF THE AREA WILL BRING MVFR OR IFR CEILINGS BACK INTO SOUTHERN NEW HAMPSHIRE AND SOUTHWEST MAINE THIS MORNING WITH LIGHT RAIN POSSIBLE AT MANCHESTER AND PORTSMOUTH. ALTHOUGH CONDITIONS WILL LIKELY IMPROVE THIS AFTERNOON AS THE LOW MOVES OUT... AN EASTERLY FLOW IS EXPECTED TO DEVELOP EARLY WEDNESDAY MORNING AND SEND A FRESH BATCH OF LOW CLOUDS INTO THE AREA. THIS WILL LIKELY BRING IFR OR WORSE CONDITIONS TO MAINE AND EASTERN NEW HAMPSHIRE WHILE CONDITIONS STAY VFR WEST OF THE MOUNTAINS. LONG TERM...GENERALLY UNSETTLED WX PATTERN LOOKS TO CONTINUE INTO THE WEEKEND ACROSS THE AREA. THU INTO FRI PERSISTENT NE FLOW AND MARITIME INFLUENCES WILL KEEP WIDESPREAD MVFR AND AREAS OF IFR TO MUCH OF THE AREA. MOST LIKELY TO ESCAPE SIGNIFICANT IMPACT WILL BE INTERIOR TERMINALS...LEB AND HIE. MOVING INTO THE WEEKEND...UPPER LOW MOVES CLOSER AND WX WILL TRANSITION MORE TOWARDS DIURNAL SHRA. AFTERNOON MVFR...LOCAL IFR...SHRA WILL GIVE WAY TO VFR OR MVFR DURING THE OVERNIGHTS. && .MARINE... SHORT TERM...WAVE HEIGHTS HAVE CREPT UP TO AROUND 5 FEET SO WILL LET THE SMALL CRAFT ADVISORY CONTINUE. EXPECT GENERALLY A LIGHT NORTHEAST WIND TODAY SHIFTING TO EASTERLY TONIGHT. LONG TERM...PERSISTENT NE FLOW OVER THE WATERS WILL GRADUALLY BUILD SEAS LATE IN THE WEEK TO AROUND 5 FT OUTSIDE OF THE BAYS. DEPENDING ON THE STRENGTH OF THE PRES GRADIENT ACROSS THE REGION...SOME WIND GUSTS TO 25 KTS ARE POSSIBLE. SEAS WILL SLOWLY DIMINISH OVER THE WEEKEND. && .FIRE WEATHER... WILL CONTINUE TO SEE A PROLONGED PERIOD OF MOIST ONSHORE FLOW HELPING TO KEEP RELATIVE HUMIDITY VALUES HIGH AND RAIN IN THE FORECAST. && .TIDES/COASTAL FLOODING... BEGINNING THURSDAY THROUGH THE WEEKEND...WE ARE SET FOR A PERIOD OF HIGH ASTRONOMICAL TIDES. THE HIGHEST TIDES WILL BE FRIDAY AND SATURDAY NIGHTS WHEN PORTLAND IS FORECAST TO REACH 11.9 FEET AT 1135 PM AND 1226 AM RESPECTIVELY. COASTAL FLOODING MAY BE POSSIBLE DURING THIS TIME PERIOD...AS WINDS WILL GENERALLY BE EASTERLY TO NORTHEASTERLY. IF LOW PRESSURE DEVELOPS A LITTLE SOONER OR STRONGER...COASTAL FLOODING ISSUES COULD BEGIN AS EARLY AS THE THURSDAY EVENING TIDE. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...NONE. NH...NONE. MARINE...NONE.
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&& $$ NEAR TERM...KIMBLE SHORT TERM...KIMBLE LONG TERM...LEGRO

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