Area Forecast Discussion
Issued by NWS Portland, ME

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695 FXUS61 KGYX 161637 AAB AFDGYX Area Forecast Discussion...UPDATED National Weather Service Gray ME 1237 PM EDT Mon Sep 16 2024 .SYNOPSIS... High pressure will continue fair weather and above normal day time temperatures through mid week. Low pressure moving up the East Coast will bring low chances for rain late Wednesday and Thursday. A cold front drops south out of Canada late in the week bringing temperatures closer to normal with high pressure building in next weekend. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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1237 PM Update: Temperatures have rebounded nicely with only a few Cu keeping the vis imagery from being completely clear early this afternoon. Just a few minor adjustments for temperatures/dewpoints through the afternoon. 925 AM Update: Fog has been a bit slow to burn off in the valleys this morning...holding back temperatures a bit. Have adjusted the near term temperature trend...but expect values to quickly push towards inherited values once the fog burns off. Warm...dry day expected with 12Z GYX RAOB showing a deep warm/dry airmass aloft. No other significant changes at this time. 645 AM...Valley fog showing up nicely across the NE CONUS this morning on the nighttime microphysics graphic /still waiting on the visible/. Otherwise no changes to the forecast other than usual adjustment for current obs. Previously...Elongated W-E sfc ridge stretch across N New England today, as strong 590 dam ridge extends from the Great Lakes east to S of Newfoundland, with ridging at all heights in between. This combine with warm mid level temps near 15C, should make for a sunny and very warm day, considering its mid September. Of course, were starting off with vly fog yet again, which should burn quickly outside of the sheltered mtn valleys and the CT vly, which may take until closer to 0900 or so once again. Onshore flow develops again today, but it will develop later, and make less headway inland from the coast. So, were looking at maxes of 80-85 across most areas away from the coast and more like 75-80 on the coast.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/... The ridging from the sfc thru 500 mb remains in place tonight, and it won;t be much different from Sunday night, with valley fog likely and patchy fog in other sheltered areas. Min temps will be slightly warmer, but only by a few degrees, ranging from around 50 to the mid 50s. By Tuesday will start to see the riding across all levels start to gradually weaken, as it is impinged upon by 500 mb trough well to the NW, and 500 MB closed low associated with pseudo- tropical system moving NW toward the OH valley. Overall, forecast wont be much different from Monday with mainly sunny skies /some patchy thin cirrus will likely move in/and highs again in the 80-85 range. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... Overview: Rex blocking slowly breaks down to end the week. Temps will trend cooler...and while widespread precip remains unlikely there will be some chances for showers towards the middle of the work week. Impacts: No weather impacts anticipated in the extended...but there is a chance for some measurable rain towards the middle of the week which will be a welcomed sight. Forecast Details: As usual the breakdown of the block will be slow going. The remnants of a subtropical disturbance off the Southeast coast will drift inland and north along the East Coast. That will provide our only real chance at organized precip over the next week or so. How far north the deeper moisture and showers will make it depends on a S/WV trof forecast to drop thru the St. Lawrence River Valley. The timing may force the disturbance south of the forecast area and ultimately leave much of the area high and dry yet again. Right now ensemble probabilities of measurable rainfall are quite low...no better than climatology. I have trimmed the NBM PoP and also narrowed the window a bit...especially on the front end. Otherwise the increasing deep moisture will support diurnal isolated to widely scattered showers to end the week and into the weekend. Temps will generally slowly fall thru the week. It will start well above normal...with temps in the 80s. Increasing cloud cover will limit diurnal ranges more towards the middle and end of the week...but readings should remain in the 70s. By the latter half of the week high pressure building back in from the north should allow for some seasonably cooler overnight readings along with a return of valley fog. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... Short Term...Valley fog at KLEB/KHIE will persist until around 13Z, with a brief sunrise surprise possible at KCON, bu otherwise expect VFR into this evening. Valley fog returns tonight, and may see it make a brief appearance at a few more terminals around sunrise Tue morning. Long Term...Largely VFR conditions expected to prevail during the day thru Fri. Early in the period local LIFR expected in valley fog...especially at LEB and HIE. By the middle of the week onshore flow may allow for some marine stratus and IFR is possible at all terminals. && .MARINE... Short Term...Winds/seas stay below SCA criteria through Tuesday night. Long Term...Winds and seas expected to remain below SCA thresholds until the very end of the week. A disturbance continues north...the northeast flow along the coast will be breezy and persistent. This will lead to some gusts near 25 kt...and seas building to near 5 ft outside of the bays by Fri or Sat. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...Arnott SHORT TERM... LONG TERM... AVIATION... MARINE...