Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 302232 AFDGYX Area Forecast Discussion National Weather Service Gray ME 632 PM EDT SAT JUL 30 2016 .SYNOPSIS... High pressure will gradually shift east tonight through Sunday as a weak area of low pressure moves into southern New England. Low pressure will slowly move off the New England coast Monday and will continue to slowly drift east on Tuesday as high pressure builds in from the west. High pressure will crest over the region Wednesday and will shift offshore on Wednesday night. High pressure will hold off the coast on Thursday. A cold front will approach from the west on Friday and will cross the region Friday night. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 625 PM...This updates fine tuned pops a bit...based on latest mesoscale models...20Z HRRR/18Z NAM4K/19Z meso model blend...all of which keep the threat of showers or isolated thunder from a KLEB-KSFM line southward through at least daybreak, and probably closer to 13-15Z. This is not a significant change to the forecast and does agree with 12/18Z larger scale models that best dynamic forcing stays mainly west of CWA, but weak WAA will slowly pushinto SRN NH overnight. In this area, could see a few sprinkles this evening, but best chance for precip will be after midnight. Also, made some adjustments T/Td/Sky based on current obs and tweaked mins slightly. Previously...It will be a quiet start to the clouds increase from the W. This should keep it a few degrees warmer than last night...especially for Srn zones where high clouds will be the thickest. Farther N I think there will be enough clearing for more temps in the 50s...and patchy fog in the favored low lying areas. A s/wv trof approaches late tonight...and though WAA increase across the whole area...the strongest vorticity advection looks to pass W of the forecast area. This means showers will increase towards dawn...and be most likely for SWrn parts of NH. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Showers Sun will continue to slowly lift N and E as WAA continues during the day. I will keep likely PoP confined to Srn NH and the CT River Valley...where confidence is the highest. Farther N and E...with precip tied to WAA and not vorticity advection I feel the coverage will be more scattered to isolated. Forecast soundings do show a small amount of CAPE...especially in Srn a rumble of thunder is not out of the question. With all available guidance right now...including hi-res ensembles...the best chance for rnfl amounts approaching a half inch will from the Lakes Region of NH and S to the MA border. Upper trof continues to move overhead Sun showers will likely persist into the overnight. Without daytime heating the coverage will probably be less widespread than earlier in the day...but I think at least some PoP is warranted overnight. with abundant clouds the overnight lows will be more mild and likely remain in the 60s across the entire forecast area. && .LONG TERM /MONDAY THROUGH SATURDAY/... Broad area of weak low pressure will keep clouds and the chance of showers in the forecast for both Monday and Tuesday. Moist onshore flow will produce low clouds and area of drizzle...especially in coastal areas. Low pressure will continue to drift east on Tuesday. Should see the chance of showers decreasing during the day as best lift heads east into the maritimes. Expect clearing by late in the day as high pressure builds in from the west. Should see highs on both days in the lower to mid 70s. Sunshine will return on Wednesday as high pressure crests over the region. Highs will range from the mid 70s to lower 80s. High pressure will shift offshore Wednesday night and will hold off the coast on Thursday. Return flow will bring warmer and more humid air back into the region. Expect highs on Thursday in the lower to mid 80s. Fair weather will continue Thursday night with lows ranging through the 60s. A cold front will approach from the west on Friday. After a mostly sunny morning clouds will be on the increase during the afternoon. Showers and thunderstorms will likely arrive in northwest zones during the late afternoon and early evening and this activity will cross the region Friday night as the front continues east. High on Friday will range through the 80s to near 90. Cooler and less humid air will return for the weekend on gusty northwest winds. && .AVIATION /22Z SATURDAY THROUGH THURSDAY/... Short Term...There is some uncertainty with fog development cirrus moves in overhead. A thicker cloud layer may prevent cooling enough to preclude fog...but for now I feel it is likely enough at HIE to include in the TAF there. Otherwise VFR conditions expected overnight. SHRA move into Srn zones early in the morning...and MHT...PSM...LEB could see local MVFR in heavier SHRA. CON is less certain until the afternoon hours. SHRA are most likely for NH terminals...while it will be significantly more scattered to isolated across Wrn ME. Long Term...mvfr/ifr ceilings Monday and into Tuesday. Becoming VFR Tuesday night and remaining VFR through Thursday. && .MARINE... Short Term...Winds and seas are expected to remain below SCA thresholds thru the weekend. Long Term...SCA"s may be needed Friday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...Cempa/Legro SHORT TERM... LONG TERM... AVIATION... MARINE... is the U.S. government's official web portal to all federal, state and local government web resources and services.