Area Forecast Discussion
Issued by NWS Caribou, ME

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876 FXUS61 KCAR 190327 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 1127 PM EDT Tue Jun 18 2024 .SYNOPSIS... High pressure will remain south of the region through Wednesday night. A cold front will cross the area Thursday followed by high pressure building in through Saturday, then sliding to the east Saturday night. A warm front will lift over the area on Sunday. && .NEAR TERM /THROUGH WEDNESDAY/...
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11:25 PM Update...Temperatures are still in the upper 70s and only cooling off very slowly due to the humidity. Made some minor adjustments to cloud cover with some patchy cloudiness over western areas. Otherwise, forecast remains on track. Previous Discussion... Near record to record heat and humidity will continue to build through Wednesday as a ridge of high pressure extends north of Bermuda, bringing very warm humid air and broad southwest flow at all levels. Guidance remains consistent in showing 925mb temperatures around 27C, suggesting surface temperatures in the mid 90s even without full sunshine. Projections of mid level moisture have increased over the last 24 hours, leading to less transfer of drier air aloft towards the surface than previously anticipated. As a result, forecast dew points were increased by a couple degrees into the 72-74F range. This, combined with the air temperatures, will lead to areas around the Bangor Region and Penobscot Valley exceeding 105 degree Excessive Heat Warning criteria for a few hours Wednesday afternoon. For the first time in the history of our weather forecast office, an Excessive Heat Warning has been issued, valid for southern Piscataquis and central/southern Penobscot Counties from late Wednesday morning through Wednesday evening. Despite ample instability, convection chances remain limited over the next 24 hours due to large scale subsidence and warm temperatures aloft. Any activity this evening and again on Wednesday will remain isolated (20 percent chance or less). If a storm does form, it would be capable of producing gusty winds and briefly torrential rain. A strong seabreeze will extend across all of coastal Downeast Maine and into portions of Interior Downeast Maine tonight through Wednesday. The stability will lead to poor air quality across portions of the area, especially coastal Hancock County where the Maine Department of Environment Protection has issued an Air Quality Alert. Patchy fog is also possible over these areas later tonight into early Wednesday morning.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... Wednesday Night... Extraordinarily warm temperatures Wednesday night thanks to the very warm airmass and limited decoupling/good mixing. Went on the warm side of guidance, with lows in the low to mid 70s, except 60s along the coast. The warmest low temperatures will likely be in the north. Can`t totally rule out an isolated storm through the evening, but can`t pinpoint where the isolated storm would be, so went with broadbrushed 15-20 PoPs. Thursday... Upper level ridge begins to flatten and a surface cold front enters Northern Maine. Some uncertainty in exact timing of the cold front, and the timing of the front would determine where storms are the most abundant, and how far north the 90s make it. Right now, think the best shot at storms, which could be strong/severe, will be from Houlton and Greenville south. Also the low to mid 90s should be along and south/east of I-95, with heat advisory criteria being met again easily in these areas. In fact, Thursday should be the warmest day for immediate coastal Downeast thanks to shore-parallel or slight offshore flow. The far north will see drier, cooler air beginning to move in behind the front mid/late afternoon. Again, some uncertainty on the speed of the front, and the north/south position of the storms and the 90s could vary some. Thursday Night and Friday... Some storms Thursday evening Downeast just ahead of the cold front, then the cold front moves offshore, with at last some drier and cooler air working in from the north areawide Thursday night into Friday. The push of drier/cooler air will be stronger in the north, but all areas will have welcome relief. Highs on Friday will be in the upper 70s in the north and low 80s Downeast. Dewpoints will be in the mid to upper 40s north and low to mid 50s Downeast. Compare this to the low 70s dewpoints ahead of the cold front. Plus, there will be a decent NW breeze on Friday. No precipitation expected Friday. Models have trended stronger with the push of cooler/drier air for Thu night/Fri, and went along with this trend. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... High pressure builds in Friday night but is short-lived, as it moves east late Saturday as the next system approaches from the west. Rain chances begin to increase late Saturday afternoon into evening, but the best rain chances appear to be late Saturday night through Monday. Most models/ensembles have low pressure tracking to our north, which would bring a warm front early Sunday, eventually followed by a cold front sometime roughly Monday afternoon. Thunderstorms will be possible from Sunday into Monday. The airmass looks somewhat warm/humid in between the warm front and cold front, but not remotely as warm/humid as what we are seeing now. Quieter weather for Tuesday. && .AVIATION /04Z WEDNESDAY THROUGH SUNDAY/... NEAR TERM: VFR through the TAF period KFVE/KCAR/KPQI/KBGR. MVFR haze has formed at KHUL and should linger into the overnight hours, before dissipating and becoming VFR there. KBHB should see a period of IFR or lower conditions overnight/early Wednesday morning in fog and/or stratus, otherwise it should be VFR. Light and variable winds tonight become SW-WSW at around 10KT mid-late Wednesday morning. Northern terminals could see gusts to around 15-20KT in the afternoon. A sea breeze should back winds to the SSW/S at KBHB/KBGR respectively my mid-late afternoon. SHORT TERM: Wed Night...Mainly VFR, except possible local IFR near the coast, including BHB. SW wind around 5 kts. Thu...Generally VFR, but scattered to numerous showers and storms which would bring brief MVFR conditions and gustier winds. Outside of storms, W wind 10 kts with gusts to 20 kts. Thu Night through Sat...Other than a few storms Thu evening Downeast, looking VFR Thu night through Sat. Variable winds around 5 kts. Sat Night and Sun...MVFR/IFR possible late Sat/early Sun in rain and low clouds. Thunderstorms also possible. S wind increasing to 10 kts. && .MARINE... NEAR TERM: Winds and seas will remain below advisory levels through Wednesday. Seas will generally range around 2 to 3 feet, with winds around 10 to 15 kts. SHORT TERM: Winds/seas could get near small craft levels Wednesday night/Thursday morning, but likely stay just below. Conditions then likely below small craft until Sunday night/Monday, when there is a reasonable shot at small craft conditions from winds/seas. && .CLIMATE... Temperatures will soar under an anomalously upper level high pressure system, challenging record high temperatures and record max minimum temperatures. Multiple days of record breaking temperatures will lead to dangerous heat without a chance for reprieve overnight. June 19th High Temperature Records: (Forecast) Caribou (96)96 in 2020 Bangor (95)95 in 1995 Millinocket (96)95 in 2020 Houlton (95)95 in 2020 June 20th Max Minimum Temperature Records: (Forecast) Caribou (67)68 in 1970 Bangor (72)72 in 1931 Millinocket (71)69 in 1923 Houlton (65)67 in 1976 June 20th High Temperature Records: (Forecast) Caribou (89) 93 in 2020 Bangor (95) 95 in 2020 Millinocket (93) 96 in 2020 Houlton (91) 94 in 2020 All-time Record Highs: (Forecast, Day) Caribou (96 June 19)96 June 2020 Bangor (95 June 19/20)104 August 1935 Millinocket(96 June 19) 101 June 1907 Houlton (95 June 19)99 August 1975 All-time Record Max Minimum Temperature Records: (Forecast, Day) Caribou (69 June 19)71 in July 2018 Bangor (72 June 20) 77 in August 1949 Millinocket(71 June 20) 80 in July 1912 Houlton (70 June 19) 72 in August 2009 && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Heat Advisory until 8 PM EDT Wednesday for MEZ001>006-010. Heat Advisory until 10 AM EDT Wednesday for MEZ011-015-031. Excessive Heat Warning from 10 AM to 8 PM EDT Wednesday for MEZ011-015-031. Heat Advisory from 10 AM to 8 PM EDT Wednesday for MEZ016-017- 032. Air Quality Alert from 11 AM to 11 PM EDT Wednesday for MEZ029. MARINE...None. && $$ Near Term...Maloit/MStrauser/Bloomer Short Term...Foisy Long Term...Foisy Aviation...Maloit/MStrauser/Foisy Marine...Maloit/MStrauser/Foisy Climate...