Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 212342 AAB AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 742 PM EDT Wed Jun 21 2017 .SYNOPSIS... High pressure will build over the area Tonight and Thursday. Tropical moisture from the remnants of Cindy and an approaching frontal system will result in showers and thunderstorms Friday into Friday Night. South of the mountains drier weather will develop Saturday into Sunday. Scattered showers are possible over the mountains Saturday and Sunday Afternoons. && .NEAR TERM /THROUGH THURSDAY/... 630 pm Update: Only minor changes to the forecast thus far this evening primarily to boost cloud cover given recent visible satellite imagery showing a clouds thickening over the mountains in response to arriving mid level shortwave. Have seen a few light showers...but previous forecast has this well handled. Previous discussion below... Sfc front is just moving offshore at this time, and both T/Td drop off right behind the front. A few light SHRA may still be possible into this evening as upper lvl trough swings just n of the CWA, but these should clear out by midnight, and the best chance will be closer to the intl border. Winds should diminish during the evening, but will likely prevent decoupling until after midnight in a lot places. Lows will still be cool, as air mass is cool, and should generally be in the 50s. Could see some of the sheltered areas in the mountains decouple and drop into the mid-upper 40s. && .SHORT TERM /THURSDAY NIGHT THROUGH 6 PM THURSDAY/... Thursday should be a fine day, with temps near seasonal norms, mostly sunny skies, and low RH. Highs will reach into the mid to upper 70s in the mountains, and to around 80 on the coastal plain. Cirrus will thicken late in the western zones, but should be mostly sunny through the bulk of the day. Thursday night will see increasing clouds in the evening with showers beginning to move in after midnight, more likely in NH before daybreak. Could see thunder in the west as well. Increasing moisture above the surface could produce some low stratus on the coastal plain overnight. Low will range from the upper 50s in the north and ern zones to the low to mid 60s on the coast and in srn NH. && .LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/... On Friday leftover moisture from Cindy will try to stream north. A mid latitude jet will slow the northward push before steering the moisture east. A vort max and a diffluent flow aloft will combine with the tropical moisture/high dewpoints to enhance the potential for showers and thunderstorms. Expect the most widespread precipitation over northern areas of the forecast area due to the proximity to the vort max. Have added locally heavy rain in any thunderstorms that do form. A cold front will cross the region early Saturday. After the threat of some early showers...expect drier air to move in during Saturday. A quick zonal 500 MB flow will be over the region Late Saturday into Monday. WA couple of weak disturbance moving through this flow may result in a shower or thunderstorm but most of this period should be dry. The flow starts to sharpen...eventually into an east coast trough early to middle of next week. Models develop low pressure along the Mid Atlantic coast late Monday and move it east of the region over the Western Atlantic. At this point it looks like we should miss the rain from this system. With the upper level trough sharpens more than currently forecast the system could end up a little further west. Otherwise with a cyclonic flow aloft cant rule out isolated showers and thunderstorms during the daily diurnal temperature cycle. Expect warm and muggy conditions Friday into Saturday with seasonably cool temperature for much of next week. && .AVIATION /00Z THURSDAY THROUGH MONDAY/...
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Short Term... Summary: A cold front will continue to push offshore tonight with high pressure building into the region on Thursday. On Thursday night...a warm front will approach from the west with an increasing chance for showers and potentially a thunderstorm. Restrictions: VFR conditions will dominate through Thursday. Do expect some radiational fog at HIE/LEB in the 08-11Z timeframe early Thursday. Arriving warm front Thursday night will bring a chance for /primarily MVFR/ restrictions in showers and possibly a thunderstorm. This increasing cloudiness should preclude dense fog at HIE/LEB...but depending on timing of the precipitation...some fog is again possible. Winds: Winds go calm / light-variable this evening through daybreak Thursday before strengthening to 10g15kts from the west during the day Thursday /more southerly along the coast/. Winds again diminish to 5kts or less Thursday night. LLWS: No threat through Thursday night. Thunder: No risk through Thursday. Some chance for thunder Thursday night...primarily over New Hampshire. Long Term... MVFR with areas of IFR conditions are possible Friday and Friday night as scattered showers and thunderstorms cross the region. Patchy fog is also expected Friday Night. MVFR to VFR conditions are expected south of the mountains Saturday Afternoon into Monday. Areas of IFR are possible each afternoon over the mountains in scattered showers.
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&& .MARINE... Short Term...Winds/seas will stay below SCA levels through Thu night. Long Term... Wind Gusts and waves may approach minimal SCA levels Friday Afternoon and Evening. Otherwise conditions are expected to remain below SCA in the long term marine forecast. && .TIDES/COASTAL FLOODING... Hi astronomical high tides are expected Friday Night and again Saturday Night. Tides may exceed minor flood levels and some inundation is possible. If any surge or waves develop in addition to this then impacts my increase. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...Arnott/Cempa SHORT TERM...Cempa LONG TERM...Lulofs AVIATION...Cempa MARINE...Cempa/Lulofs TIDES/COASTAL FLOODING...

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