Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 190159 AFDGYX Area Forecast Discussion National Weather Service Gray ME 959 PM EDT Tue Jul 18 2017 .SYNOPSIS... Weak high pressure will build over the region tonight. A cold front will approach from the northwest on Wednesday and will drop south through the region Wednesday night. A shallow ridge of high pressure will build over the area on Thursday. Another weak cold front will drop south through the region on Friday followed by a secondary cold front Friday night. High pressure will build in from the northwest on Saturday and will crest over the region Saturday night. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... 955 PM...Showers have ended across the CWA, and for the most part should be done for the night. Ts running in the mid to upper 60s across most of the area, although some srn NH spots in the low 70s, with a few low 60s in the mtns. Overall, another humid night in store, with lots of fog. Dense fog likely in spots along the coast and in the usual valley fog areas as well. Low will mostly be 65-70, although cooler in the mtns and along the immediate mid coast. 550 PM...A few clusters of storms late this afternoon should begin to diminish shortly as we daytime heating. Although general forcing is very weak. There`s enough instability for storms to generate localized boundaries and forcing to produce new updrafts and keep going. Other forecast changes involve increasing sky to OVC where the coastal stratus is moving in and where it will eventually overnight, which will be covering most of the coastal plain in ME and at least moving into parts of seacoast NH. Previously...Isolated showers and a few thunderstorms will gradually fade away through the remainder of the afternoon as drier air pushes in from the west. Expect inland areas to see just partly cloudy skies this evening before extensive valley fog develops in the usual locations. Moist onshore flow will continue and looking for ocean stratus to develop this evening in coastal and southern interior sections at some point during the evening... mainly from Portland eastward. Lows will range from the mid 50s to lower 60s north and mid to upper 60s south. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... Shallow ridge of high pressure will build over the region on Wednesday. Westerly flow will send temperatures soaring under mostly sunny skies. Morning fog will quickly burn off but ocean stratus may take much of the morning to clear especially in midcoast Maine. Highs will generally range through the 80s with lower to mid 90s in southern New Hampshire and extreme southwest Maine. Weak cold front will drop south through the region Wednesday night will little fanfare other than a few passing clouds. Lows will range from the upper 50s north to the upper 60s south. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Extended forecast continues with the general theme of trofiness trying to hang around the Northeast. This will promote a series of fast moving s/wv trofs to move thru the region thru the weekend. Thu looks to be a day in the wake of one wave...and wx should be more or less fair but warm. Again Fri another weak wave looks to pass thru the area...but confidence is low on timing. That will have a large impact on both thunderstorm chances and how hot it gets. With lingering moisture some heat index values in Srn NH may push 95 degrees. More showers/storms are possible Sat afternoon...along with continued heat and humidity for Srn zones. We will have to keep an eye on heat index values once see if heat advisory criteria may be met. The strongest wave looks to be Sun/Mon...with deeper SW flow aloft and stronger forcing along the boundary. I kept likely PoP confined to this time period. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... Short Term...Areas of IFR/LIFR ceilings/vsby developing overnight...especially in valleys and coastal locations. Gradually becoming VFR Wednesday morning. VFR Wednesday night. Long Term...Generally VFR conditions to prevail thru the weekend. Some marine fog/stratus is possible ahead of approaching fronts...but confidence is low in occurrence. There will be a series of frontal boundaries that will cross the area thru Sun...with a threat for TEMPO MVFR conditions in SHRA/TSRA. && .MARINE... Short flags. Long Term...Winds and seas are expected to remain below SCA thresholds. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...Cempa/Sinsabaugh SHORT TERM...Sinsabaugh LONG TERM...Legro AVIATION... MARINE... is the U.S. government's official web portal to all federal, state and local government web resources and services.