


Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
192 FXUS61 KGYX 272236 AFDGYX Area Forecast Discussion National Weather Service Gray ME 636 PM EDT Wed Aug 27 2025 .SYNOPSIS... An upper trough will remain over the Northeast through much of this week favoring below normal temperatures and mostly dry conditions through Thursday. A cold front and low pressure then approach late in the week, bringing an increasing potential for showers on Friday. The front crosses east of the area by Saturday, but scattered daytime showers remain possible over the weekend as an upper low crosses the region. High pressure moves into the region late weekend into early next week. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... 630 PM Update...Isolated showers across the coastal plain of ME to central ME will move off to the east and dissipate over the next couple of hours. Otherwise we expect river valley fog tonight, especially the CT River Valley. Previously... 500mb shortwave continues to trek across northern New England this afternoon with scattered showers expected mostly across the southern 2/3 of NH eastward into western ME from the foothills southward. A few hundred J/kg of CAPE and cooling temperatures aloft will be sufficient enough for a few storms capable of small hail or graupel, and inverted V profiles suggest gusty outflow winds are also possible. Skies clear out behind the shortwave this evening and remain mostly clear overnight. Conditions look good for radiational cooling, and I have leaned on the cooler guidance with temperatures mostly in the 40s for lows, except northern valley could even see lows in the upper 30s. More valley fog is expected in some areas, and temperatures will be cool enough for steam/evaporation fog over many area lakes and ponds. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... Thursday begins with shortwave ridging overhead with mostly sunny skies initially (except where there is valley fog), but we`ll see increasing mid and high clouds as the day goes on with an upper low and cold front approaching from southern Quebec and the Great Lakes region. Temperatures and humidity levels remain comfortable with highs in the mid to upper 70s and dewpoints mostly in the 40s. A couple of showers are possible across the far north while the rest of the area stays dry. The upper low moves slowly eastward Thursday night roughly just north of the International Border with the front expected to be approaching VT by around daybreak. Even with lift increasing, there will be dry air to overcome, so most of the night is expected to be dry. New Hampshire may start seeing showers toward daybreak with chances increasing to 20-30%, but these will further increase on Friday (more below). With clouds possibly hindering radiational cooling, I haven`t deviated from the NBM on lows in the 40s and 50s. Fog is also not in the forecast at the moment due to the cloud cover. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Wave approaches from the west early on Friday. Trend has been for this low to slow and pivot over south central Quebec. Southern portion will continue into New England as a cold front, and this should carry some showers and storms with it. Ingredients for stronger storms will be marginal, mainly due to conditional CAPE values. Low level shear values would promote some organization to deeper showers or storms, but would need clearing/morning sun to properly set the stage for better instability. Lapse rates don`t look too bad, both low and mid levels would be supportive of strong storms per the NAM. GFS is a little more reserved with these values for the time being. Low pressure begins to slow and stack over Quebec overnight into Saturday, cutting off from main transport. With cooler air aloft creating favorable lapse rates, believe scattered showers will be around for much of Saturday, mainly in the mountains and foothills. Thin dry slot may work its way into the coast and interior to limit coverage here. Coverage decreases after sundown. Outside of the initial push of moisture, high pressure will bring more continental dry airmass into the region for Sunday and into early next week. Temperatures trend to around normal for late August and early September. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... Short Term...Mainly VFR the rest of today outside of precipitation. Scattered showers/isolated storms may bring brief restrictions at southern and coastal terminals this afternoon and early evening, and some TAF sites may require TEMPO restrictions. Fog is expected to bring restrictions to HIE and LEB tonight through around 12-13Z Thursday, but otherwise VFR Thursday. Fog is possible Thursday night at HIE and LEB and also in the AUG-RKD corridor. Long Term...Increasing chances for rain showers and possibly a couple of thunderstorms Friday into Friday night. MVFR/IFR restrictions look more likely across central ME terminals like AUG/RKD Friday night into Sunday morning. Showers remain possible over the weekend, mainly during the days, with the low pressure lingering across the area. && .MARINE... Short Term...Conditions are expected to remain below SCA levels through Thursday night. S to SW winds this afternoon will become west to northwest tonight and then southerly Thursday and Thursday night ahead of a frontal boundary and low pressure approaching from the west. Long Term...Southerly flow increases into Friday as low pressure and a cold front approach from the west, but gusts look to stay below SCA levels at this time. The front crosses sometime on Saturday with a wind shift to the west or northwest possible. High pressure builds across the waters from Sunday into early next week with conditions staying expected to stay below SCA levels. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...Combs/Ekster SHORT TERM...Combs LONG TERM...Cornwell AVIATION... MARINE...