Area Forecast Discussion
Issued by NWS Portland, ME
Issued by NWS Portland, ME
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527 FXUS61 KGYX 190223 AFDGYX Area Forecast Discussion National Weather Service Gray ME 1023 PM EDT Wed Sep 18 2024 .SYNOPSIS... High pressure lingers for one more day, but does begin to break down tonight. Moisture over the southeastern states builds north behind this high with a slight chance for showers over southern New Hampshire by Thursday. There may be a better chance for showers Thursday night into Friday as low pressure develops south of New England. High pressure builds in from the north this weekend with more seasonable temperatures and dry weather expected. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... 1020 PM Update...No big changes to the going forecast for the balance of the night. Did back off on the coastal plain fog though based on latest obs and guidance. 650 PM Update...Little change to the going forecast. The question that remains is how much fog will fill in on the coast this evening. So far webcams on the coast show very little fog at this time. Will continue to monitor. Otherwise, pretty quiet weather as per the recent usual. Previously... Current satellite imagery shows a low pressure system bringing some cloudier conditions into southern New Hampshire and coastal Maine. A fog bank over the Gulf of Maine is currently moving towards the Midcoast. Recent runs of the HRRR suggest this fog will push into the coast after sunset and then push inland past the I-95 corridor overnight. Areas of fog over along the coastal plain will linger into morning commute tomorrow with some localized dense fog possible. Radiational cooling inland is also expected to bring some fog into the Connecticut River Valley as well. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/... Areas of fog will persist along the coast through around 9 AM before dissipating. A low tracking east south of Cape Cod will try to bring moisture into southern NH and coastal areas. A few isolated showers from this low may make it into portions of the NH seacoast, York County and in Penobscot Bay. Northeasterly flow at low-levels will help usher in cooler temperatures as well, so tomorrow should feel noticeably cooler than today. Tomorrow night, we near the astronomical high tide for the month. Northeasterly flow over the Gulf of Maine might bring some splashover and building surf could lead to beach erosion to the NH/ME coastline south of Portland. Patchy coastal fog lingers tomorrow evening and builds back up by Friday morning. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... 12Z operational models and ensemble solutions continue to suggest a relatively disorganized area of low pressure will remain southeast of Nantucket Island as we begin the extended portion of the forecast. During the period Friday through midday Saturday, moisture will be attempting to reach southern portion of the forecast area as moisture from off the coastline collides with drier air over the interior. A northern and western adjustment to the QPF has occurred since yesterday. This is more consistent with the latest operational Canadian and European runs but less in par with its ensemble solutions. In any case, have raised pops across portion of the region, but still on the low side of guidance. Despite the cloud cover, temperatures will likely top out over 70 degrees in most locations. Models also remain in relatively good agreement that this system will begin to exit out to sea late Saturday allowing Canadian High pressure over the Maritimes to retrograde back into our region. This will allow for drying with any leftover showers beginning to dry up by Saturday evening. The Canadian High will allow for dry and seasonable conditions Sunday and Monday across the Northeast. Temperatures will be near normal for this time of the year. The next chance for significant precipitation will hold off until Tuesday and Wednesday of next week. A complex frontal system will enter the region from the west accompanied by a vigorous upper level trough that will track over the Great Lakes. Temperatures will be seasonably cool for this time of the year. Coastal Flooding...The onshore winds forecast for the coast on Friday will coincide with very high astronomical tides. This may lead to minor coastal flooding near the times of high tide during the early morning hours Friday, but moreso and more likely during the Friday afternoon high tide. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... Short Term... Generally VFR expected through the remainder of the day. A fog bank moves into the coast this evening, and will bring lower CIGS and visibility to RKD, PWM and PSM. Confidence is highest over the Midcoast and Penobscot Bay. Marine fog should expand overnight, reaching AUG by early tomorrow morning. Valley fog along the CT River Valley will bring LIFR conditions at LEB and HIE. Fog should mix out by 10am tomorrow. Conditions improve to VFR during the day Thursday. Low pressure spreads low clouds into southern and coastal areas Thursday night that could bring restrictions. Long Term...VFR likely prevails during the day time late Saturday and Sunday with MVFR conditions possible in scattered showers Friday into Saturday. Night time valley fog will bring the potential for IFR/LIFR most nights at KLEB and KHIE. Onshore flow and increasing clouds from a system passing south of New England will also bring the potential for cigs around MVFR thresholds Thursday night and possibly into Friday. && .MARINE... Short Term... Light and variable winds this afternoon with 2-4ft seas expected this evening. A low will slowly move well offshore from the Gulf of Maine and could bring some unsettled weather to the open waters tomorrow. The low will also shift winds northeasterly with sustained 15-20kts and gusts around 25 kts Thursday night. Seas will also increase to 3-5 feet Thursday night with SCAs likely needed late Thursday night into Friday morning. Long Term...Low pressure passing south of the Gulf of Maine will bring seas building to 5 ft by Friday with continued NE flow with gusts around 25 kts, reaching SCA criteria. Seas remain elevated around 5 feet into the weekend with NE winds subsiding from their peak on Friday. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...Ekster/Palmer/Schroeter SHORT TERM...Palmer/Schroeter LONG TERM...Cannon AVIATION... MARINE...