Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 210748 AFDGYX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAY ME 348 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/... 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 /07Z 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. && $$ NEAR TERM...CURTIS SHORT TERM...CURTIS LONG TERM...LEGRO AVIATION...CURTIS/LEGRO MARINE...CURTIS/LEGRO HYDROLOGY...CURTIS/LEGRO TIDES/COASTAL FLOODING...

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