Area Forecast Discussion
Issued by NWS Portland, ME

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000 FXUS61 KGYX 240753 AFDGYX Area Forecast Discussion National Weather Service Gray ME 353 AM EDT Tue Apr 24 2018 .SYNOPSIS...
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Southerly winds today will bring in the warmest air of the spring, though that is not saying much. Either way highs climbing into the upper 60s to near 70 will feel very welcomed. Onshore flow near the coast will keep those readings on the cooler side. As we head into Wednesday unsettled weather returns with the approach of our next storm system. Rain will overspread the area from the southwest in the morning and work northeast. A good soaking rain is expected for most of the region. This system will slowly exit the region Thursday. A cold front on Saturday will bring colder air back into the area, with a freeze possible by Sunday morning for much of the area.
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&& .NEAR TERM /TODAY/...
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Once again with models forecasting mixed layer growth to H8...I expect we should do a little better than that. Mixing down temps of +5 to +7 means we will make another run at 70...and should see those readings a little more common today. Increasing southerly flow will mean that near the Seacoast and deeper into Midcoast ME and the Capital Region will see high temps early in the day before colder marine air works inland. I used a blend of higher res guidance to show this afternoon trend. The other concern for this afternoon is fire danger. Temps will be warm again...and with dewpoints not increasing much it should mean another day with minimum RH values in the teens. Winds do increase slightly today as well...with return flow around 15 mph at times. So fire danger will be elevated...but not quite enough for a headline.
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&& .SHORT TERM /TONIGHT AND WEDNESDAY/...
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Tonight will see return flow continue and increasing clouds...so readings will be milder than the past few nights. I expect the bulk of the precip to hold off until around 8 AM Wed...as it moves in from the SW. With PWAT values some 2 standard deviations above normal...and a modest SEly LLJ...precip should be widespread and moderate to heavy at times. The good news is that it will be fairly progressive...and moving out late in the day. With precip ongoing for much of the day...high temps will be back on the cool side again. Highs should struggle into the 50s.
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&& .LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
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Upper low currently over the Tennessee Valley will slowly make its way toward the East Coast and be pulled northward toward New England on Wednesday in response to a northern stream trough. This will be our biggest precipitation maker of the forecast. While this low does pull northeast into the Canadian Atlantic, more troughs drop in through the central United States, carving out a broader trough which will be with us into the first part of next week, while also opening up the door to some colder air from the Arctic dropping down into our area this weekend. Low pressure moves through the area Wednesday night, with heavier rain falling ahead of the low in an onshore flow with a tropical connection. Could see some widespread fog as well as the moist air mass moves over the cold Gulf of Maine and condenses over northern New England. The band of persistent rain should shift east into eastern Maine Thursday morning, while the cold upper low moves in from the west, bringing more scattered showers with some terrain enhancement. Brief ridging moves by Friday morning, bringing a break from the precipitation and a chance for the sun to warm things up into the low 60s again. But another trough rotating around the periphery of the larger developing upper trough may bring some light rain Friday afternoon into Friday night mainly closer to the coast. Yesterday at this time, the GFS was alone in developing this wave into a noticeable surface low with precipitation affecting our area, but now the CMC has jumped on board as well. Even the ECMWF, while not focusing a surface low like the others, does still bring the wave close enough that its broader flow pattern still supports the idea. Thus have added/increased rain chances during this time period, though it should be fairly light. While the first periphery wave shoots off to the northeast on Saturday, a cold upper trough will be moving in out of the Great Lakes. This will bring a surge of colder air into the region along with a chance of showers as it destabilizes the low levels of the atmosphere. The brunt of this cold will be felt on Sunday and Sunday night when freezing temperatures will be possible area wide, especially if the surface high is able to build in during the night. Subsident northwest flow on Monday will keep things dry but gradually warming as an upper ridge pokes in from the west. This could bring us a bit warmer temperatures next week.
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&& .AVIATION /07Z TUESDAY THROUGH SATURDAY/...
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Short Term...VFR conditions thru most of tonight. RA moves in from the SW late tonight and spreads NEwd. Areas of IFR expected in RA during the day Wed. Long Term...LIFR conditions expected along the coastal plain in rain and fog Wednesday night, exiting to the east Thursday morning. Conditions on the other side of the mountains will be a little better, but still possibly IFR. Conditions improve a bit on Thursday, but afternoon showers will bring variable conditions especially in the north and west. Should see a break of VFR conditions Thursday night into Friday, but a low moving near the coast could bring some IFR conditions and light rain Friday evening into Saturday.
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&& .MARINE...
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Short Term...Winds and seas will remain below SCA thresholds today. Increasing onshore flow Wed will allow winds and seas to build to SCA thresholds...especially later in the day. Long Term...Onshore south to southeast flow peaks Wednesday night probably right around 30 KT before a shift to the west on Thursday. The onshore flow will bring higher wave heights, generally 5 to 9 FT with the highest in the central Gulf of Maine waters. Winds weaken as they turn westerly on Thursday, with waves taking a bit longer to subside, possibly staying above 5 FT through Friday.
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&& .FIRE WEATHER...
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Elevated fire danger is possible today as temps climb even higher than yesterday. Dewpoints will not increase much...which means more minimum RH values in the teens. S winds will increase today too...into the 15 mph range...so we may approach but stay just below red flag conditions. Cooler temps but stronger winds are expected near the coast...which may just trade off to keep the fire danger elevated there as well. Widespread wetting rain is expected Wed to diminish the fire danger.
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&& .GYX WATCHES/WARNINGS/ADVISORIES... ME...None. NH...None. MARINE...None. && $$ NEAR TERM...Legro SHORT TERM...Legro LONG TERM...Kimble AVIATION...Kimble/Legro MARINE...Kimble/Legro FIRE WEATHER...Legro

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