Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
330 FXUS61 KGYX 181032 AFDGYX Area Forecast Discussion National Weather Service Gray ME 632 AM EDT Tue Aug 18 2026 .WHAT HAS CHANGED... Areas of dense fog have settled into much of the Midcoast so have decided to issue an SPS here through 13z. We`ve seen widespread visibility observations here of a half mile or less. Patchy fog continues elsewhere. No major changes were needed for this update. && .KEY MESSAGES... 1. A weak cold front will sag into the forecast area early this morning and stall. This will aid in the development of scattered showers today. Early morning fog will be present also. A cold front approaches late Wednesday but weakens. 2. Low-impact weather is expected mid to late week, with a couple chances for light rain. && .DISCUSSION... KEY MESSAGE 1 DESCRIPTION... A weak cold front will remain stalled across the forecast area today. After early morning fog (some possibly locally dense) and a few showers, we`ll expect variable clouds. In addition the weak front should provide modest convergence to allow for widely scattered convective showers and isolated thunderstorms to develop. Nothing strong or severe expected. Dewpoint values will be up there though, making it feel quite muggy. The return of fog is expected again tonight, some of it possibly locally dense as the moist airmass remains stagnant. Wednesday will be a warmer day and feature more sunshine as well. It will also be drier in terms of mugginess. A cold front will approach from the west late in the day. However, timing seems such that it will be too late to deliver any sort of thunderstorm activity. KEY MESSAGE 2 DESCRIPTION... If the front continues to slow as the parent low occludes east of Hudson Bay, then it may wind up draped across the forecast area or just to the east. This would be the eventual pathway for low pressure across the Ohio Valley to track into the latter half of the week. Thus precip chances Thursday and Friday could eventually be in flux. High pressure should be nearing the region come the weekend, but there will be the complicating factor of the slow moving boundary exiting, mentioned above, and a potential cut off low or trough arriving from the west. The combination of the low and return flow could spell for a damp period across much of the Northeast, but anticipate some slowing of the low`s transit east which could help the first half of the weekend remain dry. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... THROUGH WEDNESDAY...Widespread LIFR/IFR restrictions continue early this morning in low clouds and fog. Fog should start to lift over the next hour or two. Isolated afternoon showers may lead to brief restrictions but timing/coverage uncertainty precludes mention at any specific site forecast for now. IFR conditions are once again expected in fog tonight into early Wednesday morning. Outlook... Thursday: Mostly VFR. Some low ceilings are possible NW of the mountains for terminals such as HIE with SHRA. Also can`t rule out lower ceilings or fog towards Penobscot Bay. Thursday night and Friday: VFR, no sig wx. Saturday: VFR likely, no sig wx. && .MARINE... Winds and seas likely remain below SCA levels through the rest of the week. Areas of fog will be possible through Thursday. A cold front approaches the waters midweek, as a wave of low pressure passes south of New England and into the Gulf of Maine or open Atlantic. High pressure builds in for the end of the week and into the weekend, before another front likely approaches by late weekend. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ DISCUSSION...Clair/Ekster/Hargrove