


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. --297 FXUS61 KGYX 100922 AFDGYX Area Forecast Discussion National Weather Service Gray ME 522 AM EDT Thu Jul 10 2025 .SYNOPSIS... Scattered showers will continue today 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 /THROUGH TODAY/...-- Changed Discussion --520 AM Update...Mostly made adjustments to PoP as showers on the northern edge of and MCV continue to stream into the southern New Hampshire and southwestern Maine. Overnight these showers were light and generally remain light with more isolated moderate rates just now starting to be reported by gauges in southwestern New Hampshire. This will have to continue to be monitored through the early morning, before attention turns to expected convection this afternoon. Previous 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 /TONIGHT THROUGH FRIDAY/... Impacts and Key Messages: * No significant weather impacts expected. Tonight: Shower and thunderstorm coverage will diminish as we head into the evening, but broad upper level troughing overhead will continue to provide some forcing and support some isolated showers through the overnight period. I would imagine these would be mainly in and around the terrain where orographic lift would provide additional forcing. Otherwise, a cool night is expected with temperatures dropping into the upper 50s and low 60s. Friday: Friday looks mostly dry as the frontal boundary that has hung around all week, finally retreats well south of New England. The upper trough axis will cross the area during the day which may again aid in the development of some mountain showers and/or storms. Ridging will begin to build in during the afternoon and generally we should see clearing skies and the beginning of a warming trend with high temperatures climbing into the upper 70s and low 80s. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Evening update...No significant changes to the long term forecast with inclusion of the latest NBM. Deep layer ridging should keep the first part of the weekend mostly dry. Then our summer pattern will return in full swing with chances for afternoon showers and thunderstorms each day next week. We will also see a trend toward above normal temperatures heading into the middle of next week. Previous Discussion... 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. 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 /09Z THURSDAY THROUGH MONDAY/... Short Term...Any fog and low ceilings should improve slightly to at least MVFR by late morning. MVFR is expected to prevail through much of today with maybe some of the more northern terminals able to pop into VFR for a bit in the afternoon. Abundant low level moisture, especially in areas where it rains/storms today, will see low ceilings and or fog develop again tonight bringing most terminals down to at least IFR overnight. Friday should see more VFR as mid levels dry out and skies clear. HIE may see some brief showers/storms Friday afternoon. Long Term...Quiet weather 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...Wind gusts and seas remain below SCA criteria through Friday as the waters remain on the periphery of high pressure. Areas of fog are likely through at least tonight. A few thunderstorms may move over the waters this afternoon. 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...Baron/Legro SHORT TERM...Baron/Legro LONG TERM...Baron/Venarsky