


Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
136 FXUS61 KGYX 131842 AFDGYX Area Forecast Discussion National Weather Service Gray ME 242 PM EDT Wed Aug 13 2025 .SYNOPSIS... Hot weather continues today before a cold front cools things off a bit for Thursday. Scattered thunderstorms develop both this afternoon and Thursday, some of which may be strong. However widespread wetting rainfall is unlikely, and most locations will see little aid to growing deficits. The weekend looks to be dry at this time with a warming trend this weekend. && .NEAR TERM /THROUGH TONIGHT/... Showers and thunderstorms are developing to the west, approaching western NH at this hour. Advancement east has been slow, but pre-frontal trof will accelerate showers and storms as the day goes on. RAP analysis shows limited instability over bulk of the forecast area. This aligns with limited cumulus development so far today. Where moisture is more abundant, this field is thicker...across mostly western locations. Expect instability to increase resulting in isolated to scattered thunderstorms slowly moving east this afternoon. SPC Marginal Risk continues to highlight the threat for gusty to strong winds where taller cores may collapse due to lack of shear and narrow updrafts. Storm intensity wanes this evening with loss of daytime heating. By then, HRRR runs have been bringing showers and storms through the western ME mountains and southern NH. Overnight, some isolated showers may continue given remaining elevated instability. As far as rainfall, storms have a limited footprint, and any benefit to the increasingly dry conditions will be minimal. While storm motion is slow, leading to showers or storms training or backbuilding, precip efficiency parameters are not overly concerning. More progression may also be derived if clusters can form ahead of an induced cold pool. Under cloud cast, lows tonight will be mild, in the upper 60s to around 70. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... Cold front will make its push across the forecast area Thursday. Temps again warm into the upper 80s, but not go much higher. Showers and thunderstorms develop ahead of the front. Depending on its progression and timing in the afternoon, areas with chances of thunderstorms may still include much of the interior and coast. Storms may be more isolated tomorrow, pushing towards the coast by late afternoon. Similar storm environment exists with decent CAPE and PWATs, but limited shear and mid level lapse rates. Some question as to how much moisture will be added to the BL, which could reduce gusty wind threat for Thursday`s storms. Once the front slides through, precip should shut off quicker than this evening. Temperatures will also be more refreshing with lows into the lower 60s for most locations, with 50s across the mountains. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Temperatures are expected to be in the low to mid-80s for Friday, with a clear and dry day expected. Dry and warmer weather is expected to continue through the weekend, as a 500mb ridge builds in across the central US. An upper-level low over Quebec slides down into the Canadian Maritimes on Sunday, potentially allowing for a couple showers and storms to pop up across the interior during the day Sunday. Prior to the frontal passage, the weekend is expected to see a warming trend. Highs look to be in the mid to upper 80s Saturday and then lower 90s Sunday. The aforementioned upper-level low should bring lasting cooler weather into the area, with high pressure building in for next week. High temperatures next week look to be in the mid to upper 70s. High pressure should hang on all week, leading to prolonged dry weather. Very dry weather next week will likely worsen the drought conditions that are being felt at the moment. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... Short Term...SHRA and TS push east across NH this afternoon and early evening. These may include gusty, erratic winds and rainfall that reduces visibility. IFR deck has docked with the midcoast of ME, and will likely advance inland as daytime heating abates. Would expect some build down fog from this as well to affect RKD and AUG overnight. Uncertainty on valley fog development tonight, but some lower stratus is possible for LEB to HIE late. Another round of SHRA and TS for interior and coastal terminals Thursday as cold front finally slides east. Long Term...VFR generally expected through the entire period. A few brief windows of lowered restrictions are possible on Sunday evening as a few thunderstorms move through the area. && .MARINE... Short Term...Below SCA conditions expected as some showers approach this evening. Cold front will near the waters during the day Thursday with wave heights generally 1 to 3 ft from bays/harbors out to the outer coastal zones. Southerly winds today and tonight turn NW Thursday evening. Long Term...Northerly winds pick up briefly on Friday morning, with 12-20kt winds expected. SCA issuance is possible for winds. Winds slacken and become light and variable by the end of the day on Friday and stay light through daybreak Saturday. Saturday afternoon, winds pickup from the south, with 7-12kt winds expected. Winds shift to southwesterlies by Sunday morning, with wind speeds remaining in the 7-12kt range. By Monday morning, winds shift to northerlies at 9- 14kts. Seas will remain at 2-4ft through the entire forecast period. && .CLIMATE... Daily record highs and year(s) for Portland, Augusta, and Concord. Portland Augusta Concord Aug 13 99F (1947) 94F (2004) 99F (1944) && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Heat Advisory until 8 PM EDT this evening for MEZ012>014- 018>022-033. Air Quality Alert until midnight EDT tonight for MEZ018>028. NH...Heat Advisory until 8 PM EDT this evening for NHZ010-012-013. MARINE...None. && $$ NEAR TERM...Cornwell SHORT TERM...Cornwell LONG TERM...Palmer