


Area Forecast Discussion
Issued by NWS Portland, ME
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Issued by NWS Portland, ME
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-- Discussion containing changed information from previous version are highlighted. --039 FXUS61 KGYX 100240 AAA AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 1040 PM EDT Wed Jul 9 2025 .SYNOPSIS... Scattered showers will continue into Thursday as a frontal boundary waffles just south of the area, before clearing out by Friday. The Bermuda high will be in place through the weekend, supplying mostly dry and warm weather. The ridge breaks down for the start of the new work week, with a return of hit and miss showers and warming temperatures. && .NEAR TERM /UNTIL 7 AM THURSDAY MORNING/...-- Changed Discussion --Northwestern portions of the forecast area continue to hold onto some meager MUCAPE...but it is sustaining isolated convection at times. There is not much in the way of organized forcing...so I will keep slight chance to chance PoP going thru most of the night. Otherwise there will be some threat for fog to move inland tonight. It is currently masked by higher clouds on satellite...but the peeks I am able to see show it moving westward across the Gulf of ME. Hi-res guidance suggests this will arrive at the local coastline between midnight and 2 AM. I have used the latest HRRR for timing...but left things at visibility higher than dense fog criteria given the uncertainty. As we near sunrise the synoptic situation changes. A S/WV trof will pivot into the St. Lawrence River Valley and the upper jet will begin to strengthen. The forecast area will be in the right entrance region of that jet streak...and the resulting forcing for ascent will support more widespread coverage in convection by morning. Heading into the afternoon...diurnal heating will lead to greater instability and more robust convection. While the strongest storms should remain west of the forecast area based on latest ensemble and machine learning guidance...the PWAT values will remain elevated and torrential rainfall will be possible with any shower or storm. Once again we will have to keep a close eye on training storms for any flooding potential.-- End Changed Discussion --&& .SHORT TERM /7 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... Tomorrow looks wetter overall than today, with more widespread showers and some scattered thunderstorms. After the bulk of the morning activity, storms likely develop again the afternoon across western areas where more sunshine and warmer temperatures are expected through the daytime. Highs likely warm into the upper 70s through the Connecticut River Valley, helping to fuel the afternoon storms, while low to mid 70s are expected elsewhere with more showery conditions. Showers diminish again tomorrow evening as the front presses a little further south of the area. Northern areas likely hold onto the scattered shower activity the longest as storms weaken and drift northeastward through the evening and early overnight hours. Temps cool a bit more tomorrow night, with lows generally expected to dip into the upper 50s to low 60s across the region. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... Key Takeaway:Typical summertime pattern expected over the long term. High pressure builds in over the weekend, followed up by a series of weak upper level systems that will push across the area bringing unsettled hit/miss weather through the rest of the work-week. Hit or miss showers possible, but no widespread rainmakers or otherwise significant weather anticipated at this time. High pressure will begin sliding into the region during the day on Friday as the front that brought showers and thunderstorms on Thursday departs eastwards off the coast. Orographic lift forced by westerly flow over the mountains may cause some scattered afternoon showers and thunderstorms but most of the coastal plains area should be relatively quiet. The 500 mb ridge and the subsequent surface high builds in further on Saturday and into Sunday likely bringing warm and dry conditions. Light flow could support sea fog development and will need to watch for any coastal impacts both Saturday and Sunday mornings. Into the latter parts of Sunday and beyond, the ridge breaks down with a more zonal flow developing. Subtle shortwaves in the 500 mb flow regime combined with typical summer-like moisture and diurnal instability could allow for more showers and thunderstorms to develop early next week. However, because of the subtleness of these features and our temporal proximity to the event, confidence is low at the timing of each wave. There is also a signal for the middle of next week for anomalously warm and humid conditions as another 500 mb ridge builds back into the region so will have to keep an eye on that as well. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... Short Term...VFR to MVFR ceilings lower to IFR with a low stratus deck at most terminals tonight. Scattered showers are possible at most terminals late tonight and into Thursday morning. The stratus deck will be slow to lift through the morning tomorrow, with MVFR possible by the early afternoon. Scattered showers and storms are possible at HIE and LEB tomorrow afternoon. Ceilings likely lower again to MVFR to IFR tomorrow night. Long Term...Quiet weather Friday into Sunday, with only an isolated threat of showers with reduced flight cats. Late night and early morning fog and stratus in the valleys and sea coast will also be possible. && .MARINE... Short Term...Conditions remain below SCA levels as a stalled front lingers south of the waters. Areas of fog continue to bring reduced visibility through at least Thursday. Long Term...Expect similar to above through the weekend and much of the work week. There will be a slight downward trend in the winds over the weekend with the surface high overhead. Waves primary SSE swells and winds for the majority of the forecast, with no significant periods above 8 seconds expected. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Legro