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Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
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361 FXUS61 KGYX 170225 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1025 PM EDT Fri Aug 16 2024 .SYNOPSIS... Mostly dry conditions expected over the weekend before more meaningful rainfall arrives on Monday with an upper-level low. Coastal areas could see some rip currents and high surf due to swell from Ernesto. Ernesto will stay well out to sea and otherwise will not impact the northeast. An upper level low sits near NEw England through mid week and will make for some slightly below normal temps, and maybe a few showers Tuesday and Wednesday afternoon. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 1025 PM Update...No changes to the going forecast. It remains on track based on latest observational data. 715 PM Update...Little change to the going forecast other than to add more stratus and fog to the forecast. This based on latest statistical model output and latest satellite imagery. Previously... Satellite imagery shows low-level stratus and some haze across southern NH and the coastal plain slowly lifting and thinning out, A stray thunderstorm is possible within the White mountains as surface instability interacts with topographic influences there. Haze is anticipated to linger through at least tomorrow morning as more vertically-integrated smoke continues to recirculate through the sky and contaminate clouds. Calm winds and diurnal processes will lead to patchy fog and low stratus developing overnight. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY/... High pressure will prevail after an upper-level low over the Canadian Maritimes continues to drift out to sea, with some low stratus likely persisting through much of the morning. General cloudiness will increase through the day as a broad synoptic scale surface low currently over the Great Lakes continue to inch towards the northeast. This low could bring some showers into the region Saturday night and early Sunday morning. Upper- level troughing will allow for a very slight cool down through the weekend. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... 500 MB pattern goes from not quite zonal weakly amplified flow, to Omega block by Monday, with trough situated over the CWA to becoming less amplified again by the end of the week. So, initially we deal with deepening closed low to our W Sunday into Monday, which will mean the best chance for precip, then the closed low sits over New England through the middle of the week, as it fills, and slowly shift NE by Friday. After the initial round of showers Sunday-Monday, itll turn much less humid and cooler through the middle week, with maybe some some isolated afternoon showers as we sit beneath a cold pool aloft, then possible a warm trend Friday into next weekend. On Sunday, the 500 Mb closed low over S ON and the lower Great Lakes will intensify and track slowly E, with Ernesto tracking N, but well S of Nova Scotia. The subsidence to the N of Ernesto and the digging trough to our W will actually allow for ridging over the CWA, and showers should only be isolated through the day. I think there will be some breaks of sun given the subsidence, but probably not near the coast where the marine layer should be established, given the persistent onshore flow from Saturday. Highs on Saturday will only be around 70 on the coast from Casco bay east, and into the mid 70s of there. Inland highs range from the low 70s in the mtns to near 80 in inland S NH. Expect showers to become more numerous and frequent Sunday night, especially after midnight. Light ESE flow and increasing Tds, should be favorable for fog in many spots as well. Otherwise, mins should mostly be in the low to mid 60s. By Monday morning, should see widespread showers and perhaps some periods of light rain. TSRA are possible as well, especially away from the coast, and some convection could produce torrential downpours. Given the onshore and rain cant see maxes varying too much across the CWA, but the warm tropical air mass should allow for max temps of 70-75 in most spots. Coolest along the mid coast. The showers and storms continue into Mon evening before, the cold front moves through and winds switch to the W, probably around or after midnight. Mins range from the upper 50s in the mtns to the low 60s in the S. Tue-Thu will be somewhat similar as the cooler air in the trough moves overhead. There will be the possibility of a few showers Tue and Wed afternoon given the cooler air aloft and the closed low overhead, and this will lead to partly sunny conditions as well, but the more part it should be dry with highs in the upper 60s to around 70 in the mtns and in the mid to upper 70s in the S. Overnight lows range from the upper 40s to low 50s in the N, to the mid 50s in the S. Still dry and maybe a little warn by Friday. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Short Term...Lingering low-level stratus and some haze continue to lower flight restrictions across New Hampshire. A stray thunderstorm could pop up over northern NH this afternoon. CIGs are anticipated to lower significantly overnight with more low stratus and fog forming in NH and western ME. Most sites are likely to go down to LIFR for a least a couple hours overnight or early in the morning tomorrow. Diurnal processes will help mix out fog tomorrow morning with low-level stratus slowly lifting out through the day tomorrow. Showers and fog possible early Sunday morning as well. Long Term...Sunday is likely to start with flight restrictions due to fog and low stratus in many spots, but should see improvement to VFR away from the coast by midday, while the coast may see a few hours of MVFR cigs in the afternoon. It looks like all terminals drop to IFR or lower in fog and low cigs Sunday night, with only minor improvement during the day on Monday with showers as well. IFR or lower expected Monday night before a return to VFR by midday Tuesday. && .MARINE... Short Term...Seas will progressively increase as Hurricane Ernesto churns over the north Atlantic. SCA Issuance is likely Saturday night for seas up to 5-7 feet. Otherwise, generally southerly winds of 7-15kts are expected tonight through Sunday morning. Long Term...Seas continue to be the main issue into early next week. The will increase, on Sunday and peak on Monday in long period swell from Ernesto. Seas away from the coast could push to around 9 ft, while near shore waves could reach to around 6 ft. The seas will begin to slowly subside late Monday night and Tuesday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...Ekster/Palmer SHORT TERM...Palmer LONG TERM...Cempa AVIATION...Cempa/Palmer MARINE...