Area Forecast Discussion
Issued by NWS Portland, ME

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000
FXUS61 KGYX 211012
AFDGYX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAY ME
612 AM EDT TUE OCT 21 2014

.SYNOPSIS...
LOW PRESSURE OVER THE EASTERN GREAT LAKES WILL MOVE TO THE
SOUTHEAST TODAY AND WILL INTENSIFY SOUTH OF LONG ISLAND
TONIGHT....BRINGING AN EXTENDED PERIOD OF RAIN TO THE AREA. LOW
PRESSURE WILL MEANDER OFF THE SOUTHERN NEW ENGLAND COAST WEDNESDAY
THROUGH FRIDAY BEFORE DRIFTING OFF TO THE NORTHEAST ON SATURDAY. A
COLD FRONT WILL CROSS THE AREA SUNDAY FOLLOWED BY A RIDGE OF HIGH
PRESSURE FOR MONDAY.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
6AM UPDATE.. HAVE INCREASED POPS FOR THIS MORNING AS A FEW OF THE
RAIN SHOWERS ARE FINALLY MAKING IT THROUGH TO THE SURFACE. NOT
EXPECTING SIGNIFICANT ACCUMULATION UNTIL LATER.

PREV DISC...LOW CURRENTLY OVER WESTERN NEW YORK WILL MOVE
SOUTHEASTWARDS THROUGH THE DAY... WITH THE SHOWERS CURRENTLY IN NY
SPREADING EASTWARDS ACROSS THE REGION. WHILE TEMPERATURES WILL
HOLD STEADY IN THE 50S... THE CLASSIC COLD AIR DAMMING SIGNATURE
IS EVIDENT IN THE ISOBARS... SO EXPECT LIGHT EASTERLY WINDS TO
CONTINUE THROUGH THE COASTAL PLAIN... RESULTING IN COASTAL FRONT
FORMATION. WAA FROM THE DEVELOPING CYCLONE WILL RESULT IN LIGHT
RAIN BY AFTERNOON... WITH THE HEAVIEST AMOUNTS ALONG THE COASTAL
FRONT.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
THE LOW WILL INTENSIFY SOUTH OF LONG ISLAND AND MOVE
NORTHEASTWARDS OVER THE BENCHMARK INTO THE GULF OF MAINE DURING
THE DAY ON WEDNESDAY. STEADY LIGHT RAIN WILL CONTINUE THROUGH THE
DAY ON WEDNESDAY AND NORTHEASTERLY WINDS WILL INTENSIFY ALONG THE
COAST WED AFTERNOON AS THE LOW DEEPENS. THE STRONGEST DYNAMICS
MOVE IN WEDNESDAY NIGHT SETTING UP FOR HEAVY RAIN.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
FOCUS IN THE EXTENDED IS IN THE EARLY PART...AS LOW PRES FEEDS
MOISTURE OFF THE ATLANTIC INTO NRN NEW ENGLAND. MODEL GUIDANCE IS
IN FAIR AGREEMENT THAT SFC AND UPPER LOW WILL STACK AND DEEPEN WED
NIGHT INTO THU. THIS IS PROGGED TO SEND A SIGNIFICANT SLUG OF PCPN
INTO PARTS OF WRN ME AND ADJACENT NH. OPERATIONAL
MODELS...INCLUDING THE ECMWF AND GFS...ARE FORECASTING 2 TO 4
INCHES TO FALL IN THE SPAN FROM 00Z THU THROUGH 00Z FRI. WITH ELY
FLOW UPSLOPING INTO THE MTNS AND COARSE MODEL RESOLUTION IT IS
REASONABLE TO ASSUME LOCALLY HIGHER AMOUNTS POSSIBLE.

ATTM THERE ARE A LOT OF FAVORABLE PARAMETERS FOR A HEAVY RNFL
EVENT ACROSS MUCH OF THE CWFA. THE 21/00Z GEFS FORECAST A -4 SD
850 MB U WIND ANOMALY. SUCH A SEASONABLY STRONG ELY JET IS A
STRONG SIGNAL FOR HEAVY QPF...ESPECIALLY FOR THE ERN SLOPES. IN
ADDITION...-3 SD 250 MB U WIND ANOMALIES SIGNAL THAT SLOW FORWARD
MOVEMENT OF THE SYSTEM IS LIKELY. THIS IS NOTABLE CONSIDERING THE
OPERATION GFS IS FAIRLY PROGRESSIVE WHEN COMPARED TO THE 21/00Z
ECMWF. SREF MEAN QPF AT KPWM IS JUST ABOVE 3"...WITH A CLUSTER OF
MEMBERS NEAR 4". ECMWF ENSEMBLES ALSO SHOW NEARLY HALF OF THE 51
MEMBERS AT OR ABOVE 5" TOTAL QPF THRU THU. THAT BEING SAID...SOME
MODEL GUIDANCE SUGGEST SOME DRY SLOT ISSUES WRAPPING AROUND THE
SYSTEM WHICH COULD SIGNIFICANTLY AFFECT PCPN. GIVEN THAT THE
HEAVIEST RNFL IS STILL MORE THAN 48 HOURS OUT...WOULD LIKE ANOTHER
SUITE OF GUIDANCE BEFORE MAKING ANY HEADLINE DECISIONS. WILL
ALLOW THE DAY SHIFT TO REVIEW LATEST GUIDANCE IN THIS CASE.

EVENTUALLY LOW PRES MEANDERS OFF TOWARDS THE CANADIAN MARITIMES.
WX WILL REMAIN UNSETTLED THOUGH...AS NRN STREAM S/WV TROF RACES SE
ACROSS CANADA AND DRIVES A COLD FNT THRU NEW ENGLAND ON SUN. THE
UPPER LOW CROSSING THE AREA WILL LEAD TO SCT SHOWERS...ESPECIALLY
ACROSS THE HIGHER TERRAIN. WILL HAVE TO MONITOR TRENDS...AS ECMWF
IS COOLER THAN THE GFS...AND ONLY A DEGREE OR SO FROM BEING SHSN
ACROSS THE MTNS. HIGH PRES WILL THEN TAKE CONTROL FOR EARLY NEXT
WEEK.

&&

.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
SHORT TERM... VFR CEILINGS WILL REMAIN THROUGH THE MORNING...
BEFORE CEILINGS DESCEND ALONG THE COAST AS RAIN MOVES IN TONIGHT.
BY TONIGHT... IFR CONDITIONS ARE EXPECTED ALONG THE COAST... WHILE
LEB AND HIE MAY REMAIN MVFR. WEDNESDAY WILL SEE ALL LOCATIONS
REMAIN IN IFR. LLWS WILL BE A CONCERN FOR PWM...RKD... AND PSM.

LONG TERM...IFR CONDITIONS PROBABLE WED NIGHT THRU THU IS
RA...HEAVY AT TIMES. COASTAL TERMINALS WILL SEE GUSTY NE WINDS AOA
25 KTS AT TIMES. KHIE WILL ALSO SEE DOWNSLOPING WINDS THAT COULD
BE GUSTY AT TIMES FROM THE E. MVFR CONDITIONS LIKELY LINGER THRU
THE WEEKEND...WITH SCT SHOWERS POSSIBLE IN THE MTNS ON SAT AND
SUN.

&&

.MARINE...
SHORT TERM...
WINDS/SEAS WILL BE CALM FOR TUESDAY..BEFORE BUILDING AHEAD OF THE
STORM TUESDAY NIGHT. SUSTAINED GALE FORCE WINDS ACROSS THE OUTER
WATERS FOR WED...WITH GUSTS TO GALE IN THE BAYS. SEAS WILL BUILD
TO 10 TO 12 FT IN PROLONGED NORTHEASTERLY FLOW.

LONG TERM...GALE FORCE WIND GUSTS ARE LIKELY WED NIGHT INTO THU.
SCA CONDITIONS WILL LINGER INTO SAT...BEFORE HIGH PRES TAKES
CONTROL OF THE WATERS.

&&

.HYDROLOGY...
MAIN STEM RIVERS WILL NEED TO BE MONITORED CLOSELY MID TO LATE WEEK.
MOST SMALL RIVERS AND STREAMS WILL LIKELY HAVE SHARP RISES AS
WELL. THE HEAVIEST RAINFALL IS EXPECTED TO BE OVER SOUTH-CENTRAL
MAINE AND THE NORTHEAST FACING HIGHER TERRAIN. AGAIN...MOSTLY 2-3 INCHES
QPF WITH LOCALIZED AMOUNTS APPROACHING 5 INCHES.

&&

.TIDES/COASTAL FLOODING...
ASTRONOMICALLY LOW TIDES WILL PREVENT WIDESPREAD COASTAL FLOODING
PROBLEMS... HOWEVER PROLONGED NORTHEASTERLY FLOW MAY RESULT IN
AROUND A 1 FT SURGE. COMBINED WITH 10FT WAVES THIS MAY CAUSE BEACH
EROSION AND SPLASHOVER... ESPECIALLY IN NEW HAMPSHIRE AND YORK
COUNTY MAINE.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...NONE.
NH...NONE.
MARINE...GALE WARNING FROM 2 AM WEDNESDAY TO 8 AM EDT THURSDAY FOR
     ANZ150>154.

&&

$$
SYNOPSIS...
NEAR TERM...CURTIS
SHORT TERM...CURTIS
LONG TERM...LEGRO
AVIATION...CURTIS/LEGRO
MARINE...CURTIS/LEGRO
HYDROLOGY...
TIDES/COASTAL FLOODING...



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