Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 151739 AFDGYX Area Forecast Discussion National Weather Service Gray ME 139 PM EDT Sat Jul 15 2017 .SYNOPSIS... An upper level trough will cross northern New England today, while weak low pressure passes to our south. Scattered showers and widely scattered thunderstorms will occur along and in advance of this trough today. As the trough exits tonight, 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. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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140 PM Update...Not too many changes to the going forecast at this time. Scattered showers are developing as forecast across western and northern zones. This should continue to develop and push eastward for the remainder of the afternoon. A few rumbles of thunder not out of the question. 1030 AM Update...Have updated the forecast based on trends in latest obs as well as mesoscale model data. Clouds will continue to hang tough today in the east, but breaks are already occurring in the west which should allow for a good amount of heating there. Weak short wave trough and weak SB instability this afternoon should allow for scattered showers and perhaps isolated thunderstorms away from the coast. Previously... 614 AM...Minor ESTF update to reflect the current mesonet in near term grids. Prev Disc... At 06z...GOES water vapor imagery showed a shortwave impulse over the eastern Great Lakes with an associated weak 1012 millibar surface low vicinity of /CYUL/ Montreal. NWS Doppler Radar showed widely scattered convection across the region associated with this weak system. For today...this weak system continues eastward across the forecast area. We`ll see partial clearing across much of New Hampshire during the afternoon...although with the continued risk of a brief shower or thundershower. Over Maine...a mostly cloudy day in onshore flow and with the disturbance not exiting the coast until evening. Scattered convection along and ahead of the weak disturbance with widely scattered convection behind it that will end this evening with passage of the upper support and loss of daytime heating. Highs will range from the mid 70s to near 80 in New Hampshire...while persistent clouds and light onshore flow keep highs in Maine within a degree or two either side of 70F.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... Partly cloudy tonight under weak ridging with pockets of stratus and fog developing overnight in light flow. Lows should be near 60. On Sunday...a cold front sags southward towards the international border and that combined with daytime heating may produce a few scattered afternoon showers and thunderstorms over northern and mountain sections. Highs Sunday should rebound to the lower and mid 80s...with 70s along mid coast Maine in an onshore flow. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... A southerly flow develops Sunday night which may bring in some fog off the Gulf of Maine into coastal sections. This southerly flow continues out ahead of an approaching trough Monday. There will be scattered showers and possibly a thunderstorm, mainly over western areas. By Tuesday, the trough will be over the forecast area, leading to more widespread shower activity. 00Z model suite remains in relatively good agreement with the timing of the passage of this system. There may be an embedded thunderstorm, however the amount of destabilization during the day may be limited by nearly solid cloud cover. The next chance of showers will arrive on Wednesday, however this precipitation will be much less widespread. Cyclonic flow aloft may bring a brief shower or two to the north and central areas. There will be a continued mainly diurnally driven chances for a shower or thunderstorm Thursday and Friday. This will be triggered by a persistent upper level trough over Canada and a cyclonic flow aloft. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... Short Term /through Sunday/...Areas of MVFR through 22z in cigs and sct -shra/-tsra. VFR tonight with lcl IFR psb in fog and stratus btw 08 - 12z Sun. VFR Sunday with sct mvfr psb aft 18z Sun in -shra/-tsra. Long Term....Mainly VFR conditions expected Monday, although some stratus and fog may develop on the coastal plain Monday night as an onshore flow develops. Showers will be more widespread on Tuesday, bringing IFR conditions to the region. Otherwise, mostly VFR conditions for much of the upcoming work week. && .MARINE... Short Term /through Sunday/...Winds and seas to remain below SCA criteria. Long Term...A weak pressure pattern will prevent Small Craft Advisory conditions over the waters through early next week. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...MLE

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