


Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
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483 FXUS61 KGYX 261846 AFDGYX Area Forecast Discussion National Weather Service Gray ME 246 PM EDT Thu Jun 26 2025 .SYNOPSIS... A front will bring chances for light showers through this evening before high pressure pushes back in from the north tonight. A warm front will lift northeast towards New England Friday bringing increasing chances for showers Friday afternoon into Friday night. Low pressure crosses Saturday bring periods of rain. Weak high pressure builds in Sunday and Monday for mostly dry weather with increasing temperatures. Temperatures and humidity continue to rise Tuesday ahead of a cold front that will bring thunderstorms Tuesday afternoon into Tuesday night. Humidity will abate behind the front Wednesday. && .NEAR TERM /THROUGH TONIGHT/... Light radar returns have been pushing west to east across the forecast area today, finally managing to overcome low level dry air. Echos have been aplenty for much of the morning and afternoon, but just over the last hour or two made it to surface observing stations. Most observations upstream have been very light, with some only noting a trace or a hundredth of an inch. Present radar trends support this onset of light showers across far southern ME and much of NH over the next few hours. High pressure to the north tonight will keep dry air present. This will tend to limit duration of showers into this evening, as well as keep cloud ceilings elevated. Thinning cloud cast should be observed across much of southern ME tonight, and this may promote some brief valley fog into the Kennebec Valley. Of more uncertainty is if the same develops towards the CT Valley. Clouds may be more dense here limiting the retreat of temperatures with otherwise dry conditions. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... Friday begins eerily similar to Thursday with mostly sunny skies across the east, but increasing cloudiness into the afternoon. High temperatures rise near Thursday`s highs, but the warmer temps look to be more concentrated towards central ME. This is primarily due to the presence of thicker clouds in the AM for much of southern NH. Winds become onshore Friday, with moisture again saturating top down for increasing shower chances into the afternoon. Don`t anticipate more steady rainfall until Friday evening. High pressure will have moved over the Gulf of ME Friday evening, its return flow aiding in moisture advection into New England. Isentropic lift will be underway to the west, and this shifts east as low pressure exits the Great Lakes into Ontario. HREF and NBM QPF has nosed north, with the western ME mountains and far northern NH first receiving the steady rain. The translation eastward along this region of lift will tend to focus greatest precip amounts along a specific axis. This has wavered by guidance and over time, as well as amounts. Noting that jet coupling isn`t as intense and a large spread through the IQR of the NBM lowers confidence in 2"+ amounts. By Saturday morning, a quarter inch of rainfall is possible for much of the CWA, with amounts nearing a half to three quarters of an inch in the mountains. && .LONG TERM /SATURDAY THROUGH THURSDAY/... A wave of low pressure will track from Lake Ontario to the Gulf of Maine Saturday bringing periods of rain. A weak area of high pressure slides across northern New England late Sunday through Monday bringing mostly fair weather with an upward trend in temperatures. Low pressure will track into the St Lawrence Valley Tuesday with heat and humidity building across the Northeast. A cold front will cross the region Tuesday afternoon and evening bringing chances for thunderstorms. Somewhat drier air moves in behind the front while troughing lingers over the Northeast into the second half of next week. The 12Z model suite is in good agreement that there will be high chances for rain Saturday while subtle north to south differences in the track of the low is producing a spread in rainfall amounts and temperatures. Mesoscale models are favoring a low track near overhead that would limit the forecast area`s residence time within the warm sector resulting in limited surface based instability and relative cool temperatures in the 60s. Event total QPF forecast is generally 0.5 to 1.5 inches with higher amounts possible in the mountains. Some elevated instability combined with high PWATs and deep warm cloud depths will bring potential for localized higher amounts in any convection that can materialize. However, 6 hour FFG is generally above 3 inches, which leads to a low risk for flood concerns with this event. Chances for rain will diminish late Saturday into Sunday morning as the wave of low pressure moves offshore. Mostly fair weather is likely across much of the area by Sunday afternoon with highs climbing into the 70s. High pressure slides overhead Sunday night and offshore Monday. This will bring fair weather with temperatures into the 80s for highs. Humidity will also start to increase and will peak on Tuesday when dewpoints will make a run into the upper 60s to low 70s. These high dewpoints combined with surface heating will likely yield ample CAPE across the forecast area for thunderstorms that will become likely Tuesday afternoon as a cold front approaches. Latest Machine Learning guidance out of CSU is showing a decent signal for strong to severe storms with this cold front. This seems reasonable with global models suggesting a frontal passage near and just after peak heating and modest height falls aloft. Temperatures look to remain seasonably warm into the middle of next week while dewpoints drop in the wake of the front. Cyclonic flow aloft will linger keeping some chances for showers in the forecast Wednesday and Thursday. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... Short Term...VFR expected for much of this evening and tonight. Some guidance is bringing lowered ceiling/vis to points near river valleys late tonight, and have included a brief mention of vicinity fog here. For now, confidence in this occuring is low due to existing cloud cover, but some may begin to thin later tonight. VFR continues Friday, but clouds thicken and lower overnight. Restrictions to MVFR and then IFR are likely first across southern NH terminals and moving northward. Long Term...Low pressure crossing the area Saturday will likely keep cigs near MVFR to IFR thresholds with periods of rain. Restrictions may linger through Saturday night before drier air moves in Sunday. VFR likely prevails Sunday into Tuesday. A cold front will bring chances for thunderstorms Tuesday afternoon. && .MARINE... Short Term...Conditions below SCA are expected. High pressure moves north of the waters tonight before settling over the Gulf of Maine Friday. This will promote onshore flow ahead of low pressure moving into Ontario Friday night. Long Term...Low pressure approaches from the west Saturday and moves through the waters Saturday night. This will bring persistent onshore winds with gusts around 20 kts and seas climbing to 5-6 feet Saturday night into Sunday. High pressure slides over the waters Sunday night and Monday. South to southwest flow increases Tuesday ahead of a cold front. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Cornwell SHORT TERM...Cornwell LONG TERM...Schroeter