Area Forecast Discussion
Issued by NWS Portland, ME

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195
FXUS61 KGYX 151634
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
1234 PM EDT FRI MAY 15 2015

.SYNOPSIS...
HIGH PRESSURE WILL SHIFT OFFSHORE TODAY AS A WEAK WARM FRONT
APPROACHES FROM THE SOUTHWEST. THE WARM FRONT WILL STALL OVER
SOUTHERN NEW ENGLAND LATE TONIGHT AND SATURDAY. LOW PRESSURE WILL
DEVELOP ON THE FRONT SATURDAY NIGHT OVER THE GULF OF MAINE AND
WILL GRADUALLY DRIFT OFF TO THE SOUTHEAST ON SUNDAY. HIGH PRESSURE
WILL BUILD IN FROM THE NORTHEAST SUNDAY NIGHT AND MONDAY. LOW
PRESSURE CROSSING SOUTHERN QUEBEC MONDAY NIGHT AND TUESDAY WILL
DRIVE A COLD FRONT TOWARD THE REGION. THE FRONT WILL PUSH EAST
THROUGH THE REGION TUESDAY NIGHT. HIGH PRESSURE WILL BUILD IN FROM
THE WEST WEDNESDAY THROUGH THURSDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
UPDATE...
HAVE UPDATED THE GRIDS BASED ON CURRENT CONDITIONS AND MESOSCALE
MODELS EARLY THIS AFTERNOON. HIGH CLOUDS WILL CONTINUE TO
THICKEN THIS AFTERNOON DUE TO ONGOING WARM AIR ADVECTION ALOFT.
HAVE SHAVED DOWN THE MAX TEMPERATURE FORECAST FOR THIS AFTERNOON
BY A FEW DEGREES DUE TO THIS CLOUD SHIELD.

PREV DISC...
ANOTHER NICE DAY ON TAP FOR THE NORTHEAST AS HIGH
PRESSURE SHIFTS OFFSHORE. HIGH CLOUDS SPILLING IN FROM THE WEST
AHEAD OF A WEAK WARM FRONT WILL DIM SUNSHINE LATER THIS MORNING
AND THIS AFTERNOON. DEVELOPING SEA BREEZE WILL CAP HIGH
TEMPERATURES IN THE 60S TO NEAR 70 IN COASTAL LOCATIONS BUT MOST
INLAND AREAS SHOULD TOP OUT IN THE LOWER TO MID 70S.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
CLOUDS WILL THICKEN OVERNIGHT AS THE WARM FRONT LIFTS NORTHEAST
INTO SOUTHERN NEW ENGLAND WHERE IT WILL STALL AFTER MIDNIGHT. WEAK
OVER-RUNNING MAY PRODUCE A FEW SHOWERS AFTER MIDNIGHT WITH HIGHEST
POPS IN THE CONNECTICUT VALLEY AND SOUTHERN NEW HAMPSHIRE. EXPECT
OVERNIGHT LOWS TO GENERALLY RANGE THROUGH THE 40S TO NEAR 50 IN
FAR SOUTHERN NEW HAMPSHIRE.

WARM FRONT STALLS OVER SOUTHERN NEW ENGLAND BY SATURDAY MORNING.
NORTH OF THE FRONT AN INCREASING ONSHORE FLOW WILL BRING OCEAN
STRATUS INTO MUCH OF THE REGION DURING THE MORNING AND EARLY
AFTERNOON. ALONG WITH THE CLOUDS THERE WILL BE A CHANCE OF SHOWERS
OR PATCHY DRIZZLE THROUGH THE DAY. ONSHORE FLOW WILL KEEP MUCH OF
WESTERN MAINE IN THE 60S TO THE UPPER 50S IN MID COAST AREAS.
SOUTHERN NEW HAMPSHIRE AND THE CONNECTICUT VALLEY MAY EDGE INTO
THE LOWER TO MID 70S.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
UPPER TROUGH MOVING THROUGH CENTRAL AND SOUTHERN QUEBEC WILL HELP
DRIVE A FRONTAL BOUNDARY EASTWARD ACROSS NORTHERN NEW ENGLAND
SATURDAY NIGHT. WITH THE FRONTAL PASSAGE THERE WILL BE AT LEAST A
BRIEF PERIOD OF OFFSHORE WINDS WHICH WILL ALLOW WARM TEMPERATURES
TO SPREAD TOWARD THE COASTLINE. MOST OF THE AREA WILL REACH THE
70S ON SUNDAY WITH A FEW 80S POSSIBLE IN SOUTHERN NEW HAMPSHIRE.

THE UPPER TROUGH DIVES SOUTHEAST ACROSS NEW BRUNSWICK AND INTO
THE WESTERN ATLANTIC ON SUNDAY... CAUSING THE SURFACE FRONT TO
EVOLVE INTO MORE OF A WEAK SURFACE LOW OFF THE NEW ENGLAND COAST.
UPPER LEVEL RIDGING BUILDS SHARPLY BEHIND THE DIVING LOW OVER
WESTERN NEW ENGLAND. THE RESPONSE AT THE SURFACE WILL BE THE
STRENGTHENING AND WESTWARD MIGRATION OF SURFACE HIGH PRESSURE OVER
THE CANADIAN MARITIMES INTO MAINE. THE PRESSURE GRADIENT BETWEEN
THIS HIGH AND THE OFFSHORE LOW WILL BEGIN AN EASTERLY FLOW ACROSS
EASTERN NEW ENGLAND INCLUDING ALL OF MAINE AND MOST OF NEW
HAMPSHIRE BY MONDAY MORNING. AS A RESULT OF THIS ONSHORE EASTERLY
FLOW... HIGH TEMPERATURES ON MONDAY WILL BE 10 TO 15 DEGREES
COLDER THAN ON SUNDAY. LOW LEVEL MARINE CLOUD COVER MAY ALSO BE
PRESENT MONDAY MORNING AS THE FRONTAL PASSAGE NEVER REALLY GETS
RID OF THE LOW LEVEL MOISTURE. AREAS MOST AFFECTED BY THE
MARITIME AIR MASS WILL BE EAST OF THE PRIMARY MOUNTAIN RIDGES. THE
CONNECTICUT RIVER VALLEY SHOULD STILL WARM INTO THE 70S WHILE
EASTERN NEW HAMPSHIRE ONLY MAKES THE 60S AND COASTAL MAINE MAY NOT
GET OUT OF THE 50S.

RIDGE AXIS SHIFTS EAST AND IS REPLACED BY A SHORTWAVE TROUGH ON
TUESDAY WITH AN ASSOCIATED SURFACE FRONT. MOIST SOUTHERLY FLOW
AHEAD OF THIS FRONT AND LIFT ASSOCIATED WITH THE SHORTWAVE TROUGH
WILL LIKELY LEAD TO SHOWERS AS IT CROSSES THE AREA ON TUESDAY.
SOUTHERLY FLOW WILL BE ONSHORE IN NATURE ACROSS ALL OF MAINE SO
EXPECT ANOTHER COOL DAY IN THE 50S TO LOW 60S. NEW HAMPSHIRE WILL
BE A LITTLE BETTER WITHOUT THE DIRECT MARITIME INFLUENCE BUT WILL
ONLY TOP OFF IN THE 60S.

THE FRONT CROSSES THE AREA TUESDAY NIGHT GIVING WAY TO COOLER AND
DRIER CONDITIONS ON WEDNESDAY... EXCEPT NEAR THE COAST WHERE IT
WILL BE A BIT WARMER DUE TO OFFSHORE FLOW.

BROAD SURFACE HIGH PRESSURE SPREADS FROM THE PLAINS TO THE EAST
COAST ON THURSDAY AND GENERALLY SPEAKING WILL MAINTAIN ITS
INFLUENCE OVER OUR AREA THROUGH THE END OF THE WEEK... KEEPING THE
FORECAST DRY WITH A GRADUAL WARMING TREND.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
SHORT TERM...VFR TODAY THROUGH TONIGHT. MVFR/IFR CEILINGS
DEVELOPING ON SATURDAY.

LONG TERM...LOW CLOUDS POSSIBLE AGAIN BY MONDAY MORNING AS
EASTERLY FLOW RETURNS TO COASTAL MAINE AND NEW HAMPSHIRE. SHOULD
SEE THIS CLOUD LAYER BREAK UP DURING THE MORNING MONDAY AND GIVE
WAY TO VFR CONDITIONS. EVEN BETTER CHANCE OF A RETURN OF LOW
CLOUDS MONDAY NIGHT INTO TUESDAY MORNING WITH IFR OR LOWER
CONDITIONS POSSIBLE.

&&

.MARINE...
SHORT TERM...HIGH PRESSURE KEEPS CONDITIONS QUIET OVER THE WATERS.

LONG TERM...A WEAK COLD FRONT AND LOW PRESSURE CROSS THE WATERS ON
SUNDAY. HIGH PRESSURE BUILDS OVER THE MARITIMES SUNDAY NIGHT AND
BEGINS A PERIOD OF EASTERLY FLOW OVER THE GULF OF MAINE. A COLD
FRONT CROSSES THE WATERS TUESDAY NIGHT. WINDS SHOULD STAY BELOW
ADVISORY LEVELS THROUGH THE PERIOD.

&&

.FIRE WEATHER...
RELATIVE HUMIDITY WILL BOTTOM OUT IN THE LOWER TO MID 20S TODAY
BEFORE RECOVERING THIS EVENING BUT WINDS WILL BE LIGHT. SHOWERS
AND AN INCREASING ONSHORE FLOW TONIGHT AND SATURDAY WILL HELP TO
MOISTEN FUELS AND EASE FIRE DANGER.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...NONE.

&&

$$
JC



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