Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 201039 AFDGYX Area Forecast Discussion National Weather Service Gray ME 639 AM EDT TUE SEP 20 2016 .SYNOPSIS... A weak frontal boundary continued to push offshore through the Gulf of Maine this morning. A cold front over the Great Lakes will sweep eastward and cross our area late today and tonight. This front could touch off a brief shower across the higher terrain with its passage. High pressure and drier air returns tonight through Thursday. Another cold front will approach toward the end of the work week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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638 AM...minor ESTF update to ingest the current mesonet into near term grids. Prev Disc... At 06z...a weak frontal boundary was situated just offshore and moving slowly eastward. A cold front was over the upper Great Lakes with a warm front extending eastward through Quebec province and northern Maine. Widespread low clouds and fog were found across the forecast area with little change in conditions expected through sunrise. NWS doppler radar mosaic showed a band of offshore showers associated with the weak departing frontal boundary. Another area of showers was noted along the Quebec-Ontario border ahead of the approaching cold front. For today...low clouds and fog should burn off by later this morning with sunshine and warm temperatures expected ahead of the approaching cold front. It`ll be another humid day with any late day showers confined to the higher terrain and international border area ahead of the cold front. Highs today will be in the lower and mid 80s...expect for the Maine midcoast given the onshore trajectory.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/... The cold front will slide offshore overnight. Clearing skies and light winds should once again allow low clouds and fog to perform...mainly across the interior valleys. Lows will be in the 50s...except for some lower 60s over southeast New Hampshire. Mostly sunny and mild on Wednesday as high pressure continues to build across the area. Highs will be mainly in the 70s...with a few 80 degree readings over southeast New Hampshire. && .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... After a warm and pleasant start to the extended...the story thru the middle of next week looks to be at least a temporary reshuffling of the pattern. Both the 20.00z GFS and ECMWF...along with the 20.00z GEFS and 19.12z ECMWF EPS agree on the overall evolution. A greater than 3 standard deviation ridge is forecast to build into far Nrn Canada...W of Hudson Bay. This strong ridging will dislodge the polar air...and with high heights in the middle of the continent we will tend towards lower heights over the Northeast. It is a favorable pattern to send the chill our direction. There may be some modification in model guidance in the coming days...but at things stand now we could be flirting with H8 temps near 0C by Sat night. That will mean a couple things. One is that we may have another round of frost or even freeze warnings if we can high pressure to arrive in time. Another is that with mid level temps that cool and upslope clouds lingering under that cold pool...it would not be that much of a stretch to see some flakes mix it at highest elevations. The cold shot does not look like it will last long however...as the air mass begins recovering as early as Sun. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... Short Term /through Wednesday/...widespread IFR/LIFR through 12z improving to vfr throughout with lcl mvfr psbl over the mtns btw 19 and 23z in -shra. Aft 04z Wed...areas of MVFR and lcl IFR dvlpg in valley stratus and fog. Bcmg VFR throughout aft 12z Wed. Long Term...The period begins with widespread VFR conditions with weak high pressure over the region. Thu night and Fri this will give way to a series of s/wv trofs that will bring periods of MVFR conditions in SHRA or -RA. The timing of the trofs will likely vary a bit in the coming days...but it looks like two distinct waves that could bring MVFR or lower conditions to all terminals. For the weekend we should see VFR return to all terminals except in the higher terrain where upslope clouds and SHRA will likely linger with the passing upper trof. So HIE and LEB may see occasional MVFR thru Sat/Sun. && .MARINE... Short Term /through Wednesday/...Quiet through Wednesday as winds and seas remain below small craft criteria. Long Term...Winds and seas generally look to stay below SCA thresholds thru early next week. As a cold front approaches the waters late this week...seas outside the bays may approach 5 ft however. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Dense Fog Advisory until 9 AM EDT this morning for MEZ023>028. NH...Dense Fog Advisory until 9 AM EDT this morning for NHZ014. MARINE...None. && $$ ES

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