Area Forecast Discussion
Issued by NWS Portland, ME

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FXUS61 KGYX 031321
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
921 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 /UNTIL 6 PM THIS EVENING/...
920 AM UPDATE...HAVE UPDATED THE GRIDS...MAINLY POP AND SKY TO
ADJUST FOR LATEST TRENDS IN OBSERVATIONAL DATA. MUCH OF THE DAY
SHOULD BE DRY FROM HERE ON OUT EXCEPT FOR PERHAPS A FEW SPOT
SHOWERS...ESPECIALLY IN THE MOUNTAINS. OTHERWISE...EXPECTED A
CLOUDY TO MOSTLY CLOUDY DAY WITH A FEW PEEKS OF SUN AT TIMES.

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.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM 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 /13Z TUESDAY THROUGH SATURDAY/...
SHORT TERM...MVFR IMPROVING TO VFR IS EXPECTED TODAY. ALTHOUGH
CONDITIONS WILL LIKELY IMPROVE THIS AFTERNOON AS LOW PRESSURE
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...SEAS HAVE COME DOWN TO BELOW 5 FT THEREFORE A SCA IS
NO LONGER IN EFFECT. 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...
ME...NONE.
NH...NONE.
MARINE...NONE.

&&

$$

NEAR TERM UPDATE...EKSTER
SHORT TERM...KIMBLE
LONG TERM...LEGRO


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