Area Forecast Discussion
Issued by NWS Portland, ME

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206 FXUS61 KGYX 161938 AFDGYX Area Forecast Discussion National Weather Service Gray ME 338 PM EDT Thu May 16 2024 .SYNOPSIS...
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A stalled frontal boundary is touching off showers and thunderstorms across the north this afternoon and evening. High pressure than builds in allowing for patchy fog tonight. Other than a weak system bringing some isolated showers on Saturday, high pressure will continue to dominate through early next week with much warmer temperatures expected.
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&& .NEAR TERM /TONIGHT/...
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Convection firing up on boundary across across central ME. Most of it is from Somerset county east, although some more isolated cell popping up all the way west in the Whites. This boundary is a weak temp boundary, but it is getting added convergence from some marine layer influence to the S, and some differentiation heating. There have been a handful of lightning pulse to our E in this line, but theres not a lot of sustained forcing, with a lack of wind across much of the vertical in the atmosphere. Expect them to diminish around and after sunset. Otherwise, thinking theres a an overall clearing trend tonight as high pressure trickles in from the NE beneath strengthening ridging aloft. The lack of flow will keep low moisture on the higher side, with Tds mostly in the 50-55 range, and so will see patch fog, more likely in places where it rained today. Mins will drop to around 50 across much of the CWA, as partial clearing will allow some rad cooling, but the higher Tds will limit the fall.
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&& .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
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Friday looks fairly decent with more sun in the morning an clouds thickening during the afternoon. The ridge does shift E, with some weak height falls later in the day, so may see an isolated shower pop up in the mtns, but should be dry most places, with highs a little warmer than Thursday away from the coast, thanks to less cloud cover, and highs in the mid to upper 60s on the coast. The onshore flow should pick up a little and move further inland Fri night ahead of the next system, so thicken clouds overnight will not be lowering temps as much as tonight, but, with the remain moving in , should mins drop to around 50 in most spots again.
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&& .LONG TERM /SATURDAY THROUGH THURSDAY/...
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Overview: The large scale pattern continues to be unsettled through the weekend although it looks like overall models have trended drier. Surface high pressure and and an upper level ridge will keep things dry and warm for the first half of next week before an upper level trough and surface front approach the region which could bring our next widespread chance for rain. Impacts: * No significant weather impacts expected Details: Surface low pressure moving up the East Coast will stay well offshore thanks to high pressure building to our northeast. However, an upper trough looks to dive through the region Saturday which may touch off some light showers mainly over New Hampshire and southeastern Maine as a vorticity maximum rounds the base of the trough. Otherwise, clouds should be gradually clearing through the day as the aforementioned surface high pressure begins to build into our area. With good mixing expected we look to warm into the upper 60s and low 70s everywhere except the coast where onshore flow from the low out at sea will likely cap temperatures in the upper 50s and low 60s. Partly cloudy skies and calm winds overnight will allow temperatures to cool into the mid to upper 40s. Skies will continue to clear on Sunday as a ridge builds in and the resulting northwesterly upper flow will begin to dry out the upper levels. Similar to Saturday, BUFKIT soundings are showing us mixing right up to 850 mb which would result in another day in the upper 60s and low 70s, with the coast continuing to be stunted by the seabreeze and ending up in the upper 50s and low 60s. Low temperatures will be a hair lower on Sunday with the clearer skies, but this still only amounts to the mid to upper 40s as 850 mb temperatures continue to warm. We return to summer for the first half of next week as high pressure and upper ridging remain directly overhead. Would expect temperatures Monday through Wedensday to have no problems getting into the upper 70s and lower 80s each day. Daily seabreeze development would keep things at the coast a bit cooler. Tuesday will be the warmest day as models suggest 850 mb temperatures as Winds/seas stay below SCA through Friday night, but seas may start to get near 5 ft early Fri morning. high as 17C. For those that might not be a fan of the heat, the advantage of the clear skies means relief will come during the night when temperatures can cool back into the upper 40s and 50s. There is some uncertainty as far as what to expect for Thursday as many signs point to a front approaching the area. The timing of this will be crucial in determining if we may see some stronger storms develop as early as Wednesday afternoon or on Thursday. This is only worth a mention here as it is at the tail end of the period, but we will continue to watch trends and evaluate over the coming days.
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&& .AVIATION /19Z THURSDAY THROUGH TUESDAY/...
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Short Term...Latest models are now showing much less of an influx of of marine stratus and fog, although KPSM seems the most likely place to drop to IFR early in the evening, and then LIFR a few hours later. Cannot rule out some IFR late at KPWM/KRKD. Inland terminals could see some fog , especially at those where rain occurred today. Everyone goes back to VFR early Fri morning, but theres a good chance for marine layer stratus and fog again Fri night. Long Term...Some MVFR ceilings are possible during the day Saturday as a weak system crosses the area bringing some light rain showers with it. Otherwise the rest of the period will be VFR with light winds as high pressure builds in.
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&& .MARINE...
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Short Term...Winds/seas stay below SCA through Friday night, but seas may start to get near 5 ft early Fri morning. Long Term...An SCA may be needed over the weekend as low pressure passes over the waters and brings seas to around 5 ft. Otherwise, high pressure builds in for next week which will bring conditions back below SCA thresholds and keep them there through this forecast period.
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&& .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR/SHORT TERM...Cempa LONG TERM...Baron