Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 150416 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1216 AM EDT Sat Jul 15 2017 .SYNOPSIS...
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An upper level trough of low pressure over the Great Lakes will move east tonight and across northern New England Saturday, while weak low pressure passes to our south. Scattered showers and widely scattered thunderstorms will occur along and in advance of this trough overnight and Saturday. As the trough exits Saturday night, clearing and drier weather can be expected that will last into Sunday. Another trough of low pressure approaches from the west late Sunday and and stalls to the west of New England Monday and Tuesday with more unsettled weather.
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&& .NEAR TERM /UNTIL 6 AM THIS MORNING/...
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1214 AM...Minor ESTF update to reflect current mesonet and radar trends in near term grids. Prev disc... 940 PM Update... Another update to adjust PoPs across the region. Showers are scarce at the moment with some moving through the Mid Coast region of Maine and more over VT and NY along a stalled front. Convection continues to weaken as it moves east. Stratus and fog were developing across the region with plenty of moisture still in place. Have lowered PoPs to slight to chance PoPs for the most part as even the CAM models are having a hard time with precipitation placement and movement. Other parameters were adjusted to reflect these ideas. 735 PM Update... Forecast was updated to adjust PoPs and weather grids based on latest CAM models and radar data. Some isolated thunderstorms are still occurring across the region with the biggest area of convection over the Moosehead Lake region. Additional cells were still forming over NY State as well as VT. Any precipitation has the potential to be heavy but basic average QPF amounts will be light. Cloud cover and dew points will keep temperatures up with readings only dropping a few degrees by morning. Previous discussion... An upper trof over the eastern Great Lakes will slowly move east tonight. Meanwhile the weak ridging off the coast will continue the light moist maritime onshore flow. The HRRR model brings the developing convection over central and upstate NY this afternoon into NH by 00z and then moves a large area of convection across the rest of the cwa by later in the evening. Will go with the likely POPS offered by models for tonight. Due to the shallow nature of the sfc maritime air mass over the region, the elevated convection developing to the west should be able to hold together as it moves across the region tonight. Will have some enhanced wording for some heavy rain and gusty winds in some of the storms through 06z tonight. Due to very little ventilation and plenty of low level moisture, will also have the mention of some developing fog overnight. Used a blend of models with more weight on the NAMDNG guidance for overnight lows which should be in the 50s.
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&& .SHORT TERM /6 AM THIS MORNING THROUGH 6 AM SUNDAY/... The upper trof moves over the area Sat and then exits northern New England to the east Sat night. Scattered showers and possibly an isolated thunderstorm will accompany the trof Saturday but come to an end by Sat evening. Preference of better detail from the NAMDNG model for max/min temps was used. && .LONG TERM /SUNDAY THROUGH FRIDAY/... An upper level trough will approach from the west on Sunday. However, short wave ridging overhead should keep most if not all showers/thunderstorms to our west Sunday. The trough gets a bit closer on Monday so the chances for showers and thunderstorms will increase in western and central zones, but still should be the hit or miss variety. The same thing can be said for Tuesday but the shower and thunderstorm activity should be a bit more widespread with better forcing for ascent moving on in. Thereafter, we should have a fair weather day on Wednesday before another short wave trough approaches and brings renewed chances for showers and thunderstorms for the end of the week. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... Short Term /through Saturday/...Variable conditions mostly MVFR to IFR tonight into late Sat in stratus clouds, sct -shra, and patchy fog. From 22z-08z wdly sct -TSRA also possible. Conditions improve to VFR aft 21z Sat. Long Term....Mainly VFR expected Sunday and Monday expected although some stratus and fog may develop on the coastal plain during the two nights as onshore flow develops. && .MARINE... Short Term /through Saturday/...Winds and seas to remain below SCA criteria through Sat night. Long Term...A weak pressure pattern looks to keep sub-sca conditions around through early next week. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ ES

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