Area Forecast Discussion
Issued by NWS Portland, ME

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155 FXUS61 KGYX 300719 AFDGYX Area Forecast Discussion National Weather Service Gray ME 319 AM EDT Sun Apr 30 2017 .SYNOPSIS...
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High pressure will crest over the region today before shifting offshore. A warm front will remain south of the region tonight and Monday and will be followed by an occluded front Monday night. A trough of low pressure will approach from the west on Tuesday and will slowly cross the region on Wednesday. High pressure will gradually build in from the west Wednesday night and will shift offshore on Thursday as low pressure approaches from the southwest. Low pressure will slowly move up the east coast Thursday night through Friday.
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&& .NEAR TERM /THROUGH TODAY/...
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High pressure at the sfc will continue to build into our region this morning before shifting offshore late in the day. This high will deliver much cooler temperatures today. WAA aloft will quickly get started late this morning and early afternoon and will result in an increase in clouds. Light rain should begin to break out across northernmost zones this afternoon and WAA forcing for ascent increases. Further south, it should be mostly dry today, although we did include some chance pops across southernmost NH midday/early afternoon as the HRRR continues to develop showers over Upstate NY which then move eastward, possibly affecting southernmost NH early this afternoon.
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&& .SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/...
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Forcing for ascent increases tonight across our northernmost zones - mainly Coos County into the western ME mountains. This is where a band of rain - locally heavy - will likely set up later tonight. This band could drop up to an inch of rain tonight through Monday morning before shifting northward. The air mass in the western ME mountains may actually be cold enough so that some light icing occurs tonight between 1 and 3 kft as seen on NAM BUFKIT profiles. For the rest of the region to the south of the mountains, we expect mainly dry weather although some drizzle is likely to develop later tonight as easterly flow moistens. The same story can be told for Monday - with an even colder day in store except perhaps the CT River Valley. Cool high pressure ridging from the northeast will remain entrenched Monday as WAA continues overhead. This will mean cool, cloudy, and drizzly conditions for most of the area east of the mountains with highs in the 40s and 50s. In the CT River Valley, temps will likely warm as downsloping occurs...possibly into the 60s.
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&& .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
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Warm front will continue to slowly lift northward Monday night and will be quickly followed by an occlusion forecast to shift into western zones by Tuesday morning. Moist onshore flow will keep low clouds and drizzle going for much of the night before showers and possibly a few thunderstorms associated with the occlusion push in from the west after midnight. Increasing southwest flow will push low level moisture eastward by Tuesday morning. Lows overnight will range through the 40s to near 50 degrees. Upper low and trapped surface reflection will gradually push in from the west on Tuesday. First half of the day not looking too bad with a mix of sun and clouds. Expect clouds and showers to edge into northwestern zones during the afternoon. Highs will top out above normal...generally ranging through the 60s to near 70. Upper low will continue to press in from the west Tuesday night and Wednesday keeping clouds and showers in the forecast through the period. Lows Tuesday night will range through the 40s and highs Wednesday in the 50s north and lower to mid 60s south. Upper low will gradually lift off to the northeast Wednesday night as surface high pressure builds in from the west. Expect clouds and a few stray showers to give way to partial clearing in the north and clearing skies downwind of the mountains after midnight. Lows will range through the 30s to near 40. Weak ridging will edge in from the west on Thursday as low pressure approaches from the southwest. After a partly to mostly sunny morning high clouds will push into southern zones during the afternoon. Highs will range from the mid 50s north to mid 60s south. Low pressure moving in from the southwest will bring rain back into the region Thursday night and Friday. Good tropical connection will bring plenty of moisture along with this system and both the ECMWF and GFS in fairly goo agreement in placing axis of heaviest precip across southern New England into the Gulf of Maine. This would keep flooding threat low for the area but this situation will have to be monitored closely through the week in the event models shift this rainfall axis farther north. Models diverge for the weekend with the new GFS spinning up another area of low pressure over the mid Atlantic states and slowly moving this system up the coast bringing more rain to the area. 12z ECMWF not showing this so forecast confidence rather low for the weekend.
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&& .AVIATION /06Z SUNDAY THROUGH THURSDAY/...
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Short Term...VFR conditions are expected today. Conditions are expected to deteriorate to MVFR tonight followed by IFR or lower during the day on Monday in low clouds and drizzle. Long Term...IFR/LIFR ceilings Monday night...improving to VFR Tuesday. Areas of MVFR ceilings in the mountains Tuesday night through Wednesday. VFR Wednesday night through Thursday.
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&& .MARINE...
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Short Term...SCA for the ocean waters until 12z this morning for gusts around 25 kt. Otherwise, sub-sca conditions expected today through Monday. Long Term... SCA`s likely Monday night into Tuesday.
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&& .FIRE WEATHER...
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Cooler conditions are expected today with light winds expected by late morning. Things moisten up substantially tonight and Monday with low clouds and drizzle expected - especially Monday. Rainfall of around an inch is possible across northern NH and the western ME mountains late tonight and early Monday.
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&& .GYX WATCHES/WARNINGS/ADVISORIES...
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ME...None. NH...None. MARINE...Small Craft Advisory until 8 AM EDT this morning for ANZ150>154.
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&& $$ NEAR/SHORT TERM...MLE

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