Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 262122 AAA AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 522 PM EDT Mon Jun 26 2017 .SYNOPSIS... A series of upper level disturbances will cross the region this week, bringing chances for showers or thunderstorms, especially in the mountains. Otherwise temperatures will be near normal with lower humidity into mid week. Warmer and more humid conditions move in at the end of the week, with a chance of showers and thunderstorms Thursday night into Friday. More chances for some storms will accompany a low pressure system Saturday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
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Update...Showers and some storms are expanding Ewd into the forecast area at this hour. I have adjusted PoP to likely for the areas I expect should see some precip in the next several hours. Latest HRRR runs show convection mainly affecting NH before weakening as it moves E. I also expect some diurnal trend down in intensity of convection after sunset. Previous discussion...A short wave trough will approach from the west for the rest of this afternoon and evening triggering scattered showers and possibly a thunderstorm, mainly across NH. This scattered precipitation will continue to progress east with time, bringing the chance for a shower to western ME and the mountains during the overnight period. Cloud cover and low surface dew points may prevent fog in many areas. However, have added patchy fog over some of the more vulnerable inland valleys, especially in NH. Overnight lows will be mostly in the 50s, but it will be chilly with some mid to upper 40s in the mountains.
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&& .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Low level lapse rates increase on Tuesday along with CAPE values. This will be in response to a mid level short wave which will be more vigorous than the previous impulses over the last day or two. Showers and scattered thunderstorms will be more widespread on Tuesday. With a cold pool aloft, there remains the potential for small hail or gusty winds in a few of the stronger storms. Will continue to highlight this possibility in the HWO, however confidence not sufficiently high enough at this time to add this hazard categorically to the afternoon forecast. Temperatures will continue to remain below normal for this time of the year. Look for highs in the 70s, except it will be chilly with 60s along the Midcoast region and in the mountains. Showers and scattered storms will continue through Tuesday evening. Thereafter, any chance for precipitation will be limited to the region of best dynamics which will once again be the northern mountain regions. Temperatures will remain below normal with overnight lows in the mid 40s north to mid 50s south. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... The deterministic models are in decent agreement on the longwave pattern into the upcoming holiday weekend. We begin the period with an upper trough draped across the northeast CONUS. This trough lifts out by early Thursday and is replaced by a low amplitude nearly zonal flow with several difficult to time weak embedded shortwave impulses. By early in the upcoming holiday weekend...one of these impulses will carve out a broad low amplitude trough centered over the eastern Plains/western Great Lakes. This trough axis will gradually migrate eastward into the Great Lakes and New England by the tail end of the holiday weekend. In the dailies...a weak surface trough crosses the area Wednesday accompanied by scattered convection. For Thursday and Thursday night a warm front will advance into New England as low pressure approaches from the Great Lakes. This east-west oriented boundary will stall across northern New England...then meander a bit north and south across the forecast area Friday through Monday as a series of weak lows track along it. This will be a period of warm and humid weather...with daytime heating and passing shortwave energy contributing to several rounds of convection during the period. && .AVIATION /21Z MONDAY THROUGH SATURDAY/... Short Term...VFR conditions are expected most areas overnight although there will be scattered showers and possibly a thunderstorm over NH and westernmost ME. There may be some patchy valley fog, mainly over NH and in the western mountains of ME. Showers and scattered thunderstorms will be a little more widespread on Tuesday into Tuesday evening with brief periods of conditions in the precipitation. Long Term... Wed - Thu...Sct MVFR in -SHRA/-TSRA. Fri - Sat...Areas of MVFR in SHRA/TSRA with lcl IFR psb vcnty of the coast in fog. && .MARINE... Short Term...Winds and seas will remain below SCA thresholds in the near/short term portion of the forecast. Long Term... Thu PM - Fri...Small Craft Conditions are possible outside the bays. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Legro

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