Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 260441 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1141 PM EST Sat Feb 25 2017 .SYNOPSIS... Unseasonably warm temperatures will come to an end tonight as a strong cold front will sweep across the region this evening accompanied by showers and a few thunderstorms. A drier and colder air mass follows this front for tomorrow into Monday. A disturbance will approach from the west late Monday and Monday night, followed by a larger system later in the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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1140 PM Update...Have cancelled the dense fog advisory as swly flow kicks in and rain helps to improve vsbys. Otherwise, rain should change to snow in the higher elevations shortly. 930 PM Update...Fineline continues to move eastward across eastern NH at this time and will move into ME shortly while slowly weakening. Wind gusts with this line have ranged between 30 and 45 kt with scattered power outages noted. No thunder, however. As this line moves across ME we expect wind gusts up to 40 kt before weakening and encountering a much more stable boundary layer. Dense fog will continue on the coastal plain until the line of showers sweeps it out. The rain will begin to change to snow shortly at higher elevations in the mountains with some accums possible overnight. 610 PM Update...Have issued a dense fog advisory for the coastal plain as well as portions of central ME and the ME mountains. Vsbys are rapidly crashing and should remain low until prefrontal convective band moves in and passes through. Otherwise, the line has weakened, but will still be watching for some winds with it across western (especially southwestern) NH. The ice jam flood potential remains. 405 PM Update...Have updated the forecast a little for a few adjustments. Two concerns for this evening are river flooding due to ice jams, and the other being the convective line approaching from the west. Line of severe thunderstorms from northeast PA extending northward to the ALB area continues to move eastward. While the severity of the line is expected to weaken considerably before reaching our CWA, it is not out of the question that a few stronger cells may affect western NH. As such have included gusty winds wording in the forecast along with the thunder. Outside chance of one or two warnings near the CT River in western NH around 00z this evening. Otherwise, we are continuing to watch for hydro concerns, mainly in NH. Previously... Warm and moist airmass in place this afternoon with a robust cold front approaching tonight. Expect conditions to remain unstable enough now to mitigate most of the fog. Good dynamics with the front should be strong enough to generate some isolated thunderstorms and up to about a half inch to three quarters of an inch of rain. Winds should come around to the north and west quickly as fropa occurs during the overnight hours.
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&& .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Cold air advection and tightly packed pressure gradient will combine to produce gusty winds across the forecast area on Sunday as temperatures begin to fall rapidly. Wind gusts are expected to stay below advisory criteria. Colder temperatures will also slow runoff and help to mitigate flooding concerns...please see the Hydrology section for more information. Wind begin to calm down Sunday night as pressure gradient weakens and wind decouples under clearing skies. && .LONG TERM /MONDAY THROUGH SATURDAY/... A weak cold front will drop south through the region on Monday. The front will push into northern zones by early afternoon producing a few snow showers. The front will continue south through the afternoon producing little more than variable clouds. Highs will range from the mid 30s to lower 40s north and mid 40s to mid 50s south. High pressure will build over the region Monday night. Expect variable cloudiness overnight with lows generally ranging through the 20s. High pressure will gradually shift off to the east as a warm front approaches from the south. Expect over-running ahead of this boundary to lift northward into southern New England during the afternoon. Will see an increasing chance of showers by late in the day across southern New Hampshire and southwest Maine. Warm front will continue to lift northward Tuesday night producing showers in southern zones and a mix of rain and snow in the mountains and foothills. Expect mixed precip to gradually go over to rain toward Tuesday morning as warmer air continues to lift north. Models showing little in the way of QPF overnight with amounts of a tenth of an inch or less. Warm front will continue to lift north Wednesday as low pressure tracks northeast out of the southern Great Lakes. Looking for occasional showers through the day with highs in the mid 40s to lower 50s. Should see a break in the rain Wednesday evening as over-running shifts north of the area and low pressure shifts northeast into the St Lawrence Valley. A trailing cold front will bring showers back into the region Toward daybreak Thursday. Lows overnight will range through the 40s. Cold front will push east through the region on Thursday as low pressure rapidly intensifies over the maritimes. Expect morning showers to give way to partly sunny skies downwind of the mountains. A strong northwest gradient will set up behind the front Thursday afternoon and may touch wind advisory criteria by late in the day. Upper trough swinging in from the west will bring snow showers into the mountains late in the day. Expect high temps to be reached in the morning before falling back in the afternoon. Highs will range through the 40s north and lower to mid 50s south. Winds will continue Thursday night and into Friday as low pressure slowly pulls away to the north. Lows Thursday night will range through the teens north and upper teens to mid 20s south.&& .AVIATION /20Z SATURDAY THROUGH THURSDAY/... Short Term /through Sunday night/...Most locations are now VFR with only a few IFR/LIFR locations remaining in fog. Those remaining locations should improve over the next few hours. Strong cold front will drag thunderstorms across the area this evening and overnight, producing a period of MVFR/IFR conditions. VFR conditions return for tomorrow, although gusty northwest winds could produce some LLWS concerns. Long Term... VFR Monday with areas of MVFR ceilings in the mountains. IFR/LIFR ceilings Tuesday and Wednesday. Becoming VFR Thursday with areas of MVFR ceilings/vsby in the north. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... Short Term /through Sunday night/...Most locations are now VFR with only a few IFR/LIFR locations remaining in fog. Those remaining locations should improve over the next few hours. Strong cold front will drag thunderstorms across the area this evening and overnight, producing a period of MVFR/IFR conditions. VFR conditions return for tomorrow, although gusty northwest winds could produce some LLWS concerns. Long Term... VFR Monday with areas of MVFR ceilings in the mountains. IFR/LIFR ceilings Tuesday and Wednesday. Becoming VFR Thursday with areas of MVFR ceilings/vsby in the north. && .MARINE... Short Term /through Sunday night/...Southerly winds increasing ahead of the approaching cold front will produce SCA criteria across the waters. After the cold front passes, gusty northwest winds are expected to produce Gale Force winds over the outer waters tomorrow. Long Term...Sca`s likely on Monday. Gales likely Thursday afternoon into Friday. && .HYDROLOGY... The flood watch remains posted for interior portions of Maine and new Hampshire through 00Z Monday. High temperatures in the 50s to 60s have resulted in a loss of 0.5-1 inch of snow water equivalent in the past 24 hours. Additionally the cold front moves through this evening with 0.50 to 0.75 inch of rain possible. The snow melt and rain will bring area rivers to near flood stage. Additionally the warm temperatures have allowed for breakup ice jam formation. Ice jam flooding occurred last night in Bethlehem NH when the Ammonoosoc River jumped 5ft in under 15 minutes. River Gauge traces show ice movement on a number of area rivers including the Sugar River, Pemi, in New Hampshire and the Wild and Swift rivers in Maine. Ice jams both form and dissolve rapidly and may form at any time. && .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...Flood Watch through Sunday evening for MEZ007>009-012>014-020- 021. NH...Flood Watch through Sunday evening for NHZ001>009-011-012-015. MARINE...Small Craft Advisory until 7 PM EST Sunday for ANZ151-153. Gale Warning from 4 AM to 7 PM EST Sunday for ANZ150-152-154.
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&& $$ NEAR TERM...Ekster

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