Area Forecast Discussion
Issued by NWS Portland, ME

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320 FXUS61 KGYX 291539 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1139 AM EDT Thu Sep 29 2016 .SYNOPSIS... High pressure will continue to build into the region from the north through Friday. Low pressure over the midwest drifts slowly north and east through the weekend. This low will eventually bring the chance of showers to the region Friday night through at least Monday. High pressure will again build in from the north by the middle of next week. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... Update... Have updated the grids based on current conditions and latest set of morning mesoscale models. Dry air continues to funnel southward, leaving the forecast area with plenty of sunshine. A cool, maritime flow will limit high temperatures to remain in the 60s this afternoon, however maximums where raised a couple degrees from previous forecast. Previous Discussion: A large blocking upper air pattern continues with a stationary upper low centered over the Ohio Valley while to the east an upper ridge axis has become wedged across northern New England. At the surface a large ridge of high pressure has become draped across northern New England supplying a dry but cool persistent low level Northeast flow. Central and mountain areas of Maine and New Hampshire will have enough dry air entrained southward to allow mostly sunny conditions while southernmost areas will have the effects of the moist Northeast maritime low level flow with clouds. Also early this morning some patchy early morning valley fog can be expected where skies clear. Temperatures will remain cool today with highs reaching around 60. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... High pressure will continue draped across the area tonight. By early Friday a wave of low pressure develops along the mid atlantic coast well to the east of the stationary upper low over the Ohio Valley. This wave of low pressure will move slowly north and push the northern fringe of moisture into extreme southern areas of the forecast area so will mention a chance of showers developing in those areas during the day on Friday. All models agree on keeping the northern fringe of precip only into far southern areas. Further north another dry but cool day expected under the axis of high pressure. Used a blend of models for min and max temps. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Chance of high impact weather: Minimal. No real changes to forecast thinking at 500 mb over the last 24 hours as closed low over the midwest CONUS remains separated from the main flow well to the north, with weak Rex blocking holding this low to our west through Saturday, before it starts lifting NE toward New England. The low eventually joins the northern stream flow as strong troughing digs equatorward over the west and pushes up a ridge over the central CONUS early next week which eventually moves into New England by the middle of next week. As for sensible wx, confidence is low as to when it will rain, but the continued slowing of the low and the strength of the ridging over the area will likely hold back precip for all but srn NH Friday night into Saturday morning, and even here will only have chance pops, as models look to produce convection over the mid-Atlantic region and then push that into the ridging over the southern CWA Fri night into Saturday. Large scale forcing and ascent look weak, so precip will either be light or the result of flattening convection moving in from the south. Will see a lot of clouds in the Fri night to Saturday frame across the south, but northern and eastern zones are likely to see some sun on Saturday. Sunday and Monday look to be the best chance for showers CWA-wide, but when and where remain the big questions. It will likely be more dry than wet both days, but will be be mostly cloudy to overcast, although could see DZ working in late Sunday into early Monday Should see improvement by the middle of the next week as low moves out and ridging moves in. Temps through the period will run close to normal for highs, and above normal for for lows, as clouds and cooler E-NE flow will limit the how much we can mix down the above normal 850 temps, running around or slightly above 10C. Highs will generally be in the 60s, with overnight lows mid 40s N to low 50s south. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... Short Term...Variable conditions through Thursday with VFR conditions over central and mountain areas with mainly MVFR conditions over southernmost areas. Some overnight and early morning valley fog til 13z will allow for lcl IFR conditions. Long Term... VFR conditions expected inland through Saturday, although could see IFR at coastal terminals and KMHT Fri night. Higher potentialfor flight restrictions Sat night into Monday in low clouds fog and DZ, especially on the coast. && .MARINE... Short Term...Persistent Northeast flow will continue SCA conditions outside the bays through Friday. Long Term... Persistent NE flow will be weakening by Saturday but should be enough to keep seas around SCA levels into Saturday before they diminish. Weak NE flow persists through Monday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...Small Craft Advisory until 7 PM EDT Friday for ANZ150-152-154. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.