Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
231 FXUS61 KGYX 151023 AFDGYX Area Forecast Discussion National Weather Service Gray ME 623 AM EDT Tue Sep 15 2026 .WHAT HAS CHANGED... Aviation section has been updated for the 12Z TAFs, but no no changes were needed to the forecast. && .KEY MESSAGES... 1. It will be the coldest morning since last spring with Frost Advisories in effect across the North Country. 2. There is a chance for rain late this week, but otherwise it will be generally dry with near to below normal temperatures. && .DISCUSSION... KEY MESSAGE 1 DESCRIPTION... Clear skies prevail across the region this morning, with only a subtle breeze delaying the drop in temps at this time. However that is expected to continue to diminish thru sunrise and temps should tumble into the 40s for much of the area. The primary concern will be the North Country valleys where widespread 30s are anticipated. A Frost Advisory remains in effect thru morning. Elsewhere it would not surprise me to see a brief upper 30s reading in the typically cool locations like SFM. With a cool start and subsidence inversion aloft, that will also make it difficult to get too warm this afternoon. Despite full sunshine it may be hard to escape the 60s today. KEY MESSAGE 2 DESCRIPTION... Much of the rest of the week will feature a fast jet to our north with a strong upper ridge centered over the southeastern CONUS to our south. That will be sufficient enough to prevent any significant warmth from entering the region, but will also lead to a frontal boundary at the very least draped near the forecast area. This is what guidance continues to key on for the next chance of rain. A cold front is forecast to wash out in the vicinity Wed and then an area of rain may track along that into our backyard for Thu. Given the uncertainty and lack of strong forcing along the boundary, I am okay with the NBM PoP around 50 percent for the local area. The stronger signal is with the next wave that approaches over the weekend. The upper ridge over the Southeast is forecast to retrograde from the late week thru the weekend. As it does so and weakens, an opening upper low will eject from the northern Rockies and head our way. Despite the fact that it is outside of our QPF window, there is a plenty of ensemble support for rainfall. NBM is already coming in with high likely PoP and that seems reasonable given the event is occurring at the tail end of the forecast range. && .AVIATION /12Z TUESDAY THROUGH SATURDAY/... Through 12Z Wednesday...IFR to LIFR valley fog at HIE and LEB should clear by 13Z-14Z this morning with conditions returning to VFR. For the rest of the day, prevailing VFR at all sites. There may be enough cloud cover to disrupt or delay valley fog development tonight, but it is prime fog season so it may be more likely than not. Outlook... Wednesday: VFR conditions expected. Thursday and Thursday night: Areas of rain showers and local MVFR conditions possible. Friday: VFR conditions expected. Saturday: VFR conditions expected. && .MARINE... Breezy northwest winds continue to diminish overnight as high pressure settles over the region. Winds and seas are expected to remain below SCA thresholds thru the remainder of the week. A stronger frontal wave will approach the waters over the weekend, and this will be the window for some areas of SCA conditions. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Frost Advisory until 8 AM EDT this morning for MEZ007. NH...Frost Advisory until 8 AM EDT this morning for NHZ001-002. MARINE...None. && $$ DISCUSSION...Legro AVIATION...Combs/Legro MARINE...Legro