Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 271337 AAB AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 937 AM EDT SAT AUG 27 2016 .SYNOPSIS... High pressure moves into northern New England today with dry and warm weather expected. The high pressure will move east into the Atlantic on Sunday with a cool onshore breeze over coastal areas. A cold front arriving from the west will bring a chance of showers and thunderstorms Sunday into Sunday night with high pressure building in behind the front through midweek. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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940 am Update... Only minor changes to the forecast this morning. Have issued the fire weather products. Fog has mixed out for the most part with a few spots remaining south of Lebanon but these will be gone soon. Temperatures will warm quickly today in a drier airmass. 630 AM UPDATE... Have updated the forecast to tie into latest temperatures early this morning. Fog in the New Hampshire valleys will be a little slow to burn off especially in the southern half of the Connecticut River Valley. ORIGINAL DISCUSSION... High pressure over the area today will bring light winds and less humid conditions. Temperatures will still be well above normal, generally in the 80s. A sea breeze can be expected along the coast, cooling temperatures a bit there.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... Light winds should allow for good radiational cooling conditions tonight, with most areas falling into the 50s. Expect valley fog to be more widespread by morning. Could also see some fog developing over the ocean spreading into coastal Maine by morning as well. With the high off to the east on Sunday, synoptic flow will be out of the southeast. This will bring a cooling ocean influence to much of Maine while interior New Hampshire warms into the mid 80s again. A couple of minor disturbances within the largely zonal flow aloft ahead of a sharp shortwave trough could help to trigger some showers and thunderstorms mainly over northern areas during the afternoon. Low level moisture return is somewhat lacking so overall instability is rather limited so severe thunderstorms are not very likely even given moderate and increasing shear. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... The extended begins with a cold front set to cross the region. Model consensus on timing is delaying the frontal passage until after dark. Showers look likely across much of the area...as the s/wv trof maintains strength and heights fall overnight. We will be missing surface based instability...but I will add thunder to the forecast even for the nighttime hours. Forecast soundings from even the GFS have some elevated instability...and a scenario like the NAM forecast soundings would make thunder even more likely. On that model...a strengthening SW low level jet will help to force convection aloft despite relatively stable surface layer. Beyond early Mon...high pressure will build in for the first half of the work week. Flow is fairly zonal aloft and should help to move systems along quickly. The next s/wv trof approaches midweek...and it is this one that helps to set the stage for Ern CONUS troffing into the weekend. Ensemble guidance continues to favor lower than normal heights and cooler than normal mid level temps. GEFS PWAT forecasts are also on the dry side...which would make sense for offshore...continental flow on the backside of the upper low. && .AVIATION /14Z SATURDAY THROUGH WEDNESDAY/... Short Term...Early morning valley fog may take a little longer than normal to burn off due to the lack of wind flow, but conditions will eventually become VFR by late morning at all locations. Expect a sea breeze along the coast during the afternoon. Fog will once again be a possibility tonight, especially at Whitefield and Lebanon. There is a lower chance of valley fog formation at Concord and Manchester, while marine stratus and fog could impact Rockland and Portland by Sunday morning. Long Term...A cold front will approach the region Sun night. SHRA and embedded TSRA look to cross the area during the overnight. Areas of MVFR conditions will be possible as the front crosses...with local IFR or lower in any heavier convection. More widespread IFR conditions may be possible if coastal fog/stratus can develop ahead of the front. Otherwise high pressure builds in behind the front...and VFR conditions will prevail into midweek. && .MARINE... Short Term...High pressure shifts into the Gulf of Maine today and tonight. Could see some fog developing over the ocean tonight, pushing toward the coast Sunday morning. Long Term...SW flow ahead of an approaching front Sun night will give way to Wly flow behind it. Persistent offshore winds may build seas outside of the bays to around 5 ft by midweek. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Hanes SHORT TERM...Kimble LONG TERM...Legro

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