Area Forecast Discussion
Issued by NWS Caribou, ME

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511 FXUS61 KCAR 271930 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 330 PM EDT Mon May 27 2024 .SYNOPSIS...
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Low pressure will track to our northwest through Tuesday. Upper level low pressure will remain over the area Wednesday into Thursday then slowly lift to the northeast on Friday.
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&& .NEAR TERM /THROUGH TUESDAY/...
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The large occluded low pressure system centered over Quebec will swing a warm front north of the region, bringing rain showers across the region tonight. Hi-res models are in good agreement with the rain showers beginning this evening and progressing from west to east throughout the night. Upper air model soundings are also in good agreement with the presence of elevated CAPE aloft. Due to the higher low level lapse rates along Downeast and the progression of the warm front, thunderstorms are expected to develop after midnight. In addition, the PWAT values above normal, mean RH above 90 percent, and a large warm cloud layer will produce heavy rain in some convective showers tonight. With the moist boundary layer and steep inversion, patchy fog will develop across the region with possible areas of fog across the south. By Tuesday, the warm front will move through the region pushing the rest of the showers off to the east by late morning. High res models and RH models show a time of brief clearing in the clouds before the cold front approaches the area. Though the passage of the warm front will stabilize the area, this clearing of clouds and sunny afternoon will help destabilize the region again. The heating of the day and the frontal lift will start producing thunderstorms in the afternoon. The ingredients are present according to several upper air soundings for these storms to create gusty winds and small hail.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
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Thunderstorms with the cold front will end quickly in the evening. The front will stall and fog will reform Downeast in the humid air south of the front. Lows will drop to the low to mid 50s. For Wednesday, the trend was towards decreasing PoPs and clouds. Nonetheless, sufficient moisture at 850mb in the northerly flow will promote cu/stratocu fields in the north. The front sags slowly southward into the Downeast region by afternoon. Convergence along the front will generate showers and thunderstorms Downeast, and possibly westward to Bangor. Some guidance such as GEMS develop a shortwave moving through the broader upper level trough to generate lift. A fair number of models develops a narrow band of SBCAPE in the 500 to 1000 J/kg range. The afternoon starts with sufficient shear to raise the chance of stronger storms, but shear rapidly diminishes as the afternoon progresses. Hail would definitely be a consideration given the low freezing level if models continue to advertise the stalled front Downeast. Strong winds seem unlikely unless there is a particularly strong cell. The front exits offshore Wednesday night with lows dropping into the 40s to near 50F. Guidance has struggled with a another shortwave rounding the base of the broad upper trough Wednesday night into Thursday and whether it would move from southern New England and brush the Downeast coast. Chances have trended lower with the latest analysis and guidance, but have maintained chance PoPs on the coast later Wednesday night into Thursday. Further north, we have trended towards less cloud cover, but seasonably cool highs in the low to mid 60s.
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&& .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
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A long wave upper trough will slowly move out of the area in favor of a high amplitude upper ridge during the period. While the upper trough remains in place, there is a chance of showers towards the coast Thursday night. A few light diurnally-driven showers may develop on Friday too, but the overall trend will be towards lower PoPs and warmer temperatures as the week draws to a close. The upper ridge begins building Friday and will crest over the area Sunday into Monday. High temperatures will move from just below seasonable norms on Friday towards slightly above normal by Sunday into Monday.
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&& .AVIATION /19Z MONDAY THROUGH SATURDAY/...
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NEAR TERM: Aroostook Terminals...VFR/MVFR conditions this evening will decrease to MVFR after sunset tonight in low cigs. After midnight conditions will decrease again to IFR/LIFR cigs/vsby in rain showers and patchy fog. LLWS all tonight. SE winds 10-15 kts. By Tuesday, IFR/LIFR conditions throughout the day with VCTS in the afternoon. SSW winds 5-15 kts. Downeast Terminals...MVFR/IFR conditions this evening will decrease to IFR/LIFR after sunset tonight and remain IFR/LIFR for the rest of tonight in rain showers and areas of fog. LLWS all tonight. SE winds 10-15 kts. For Tuesday, IFR/LIFR conditions in rain showers and possible afternoon VCTS. SSW winds 5-15 kts. SHORT TERM: Tue night...Fog is possible southeast of HUL and BGR to include locations such as Princeton, Machias and Eastport. Thunderstorms will quickly end in the evening. Otherwise VFR. Light SW winds. Wednesday...VFR. A chance of afternoon thunderstorms towards Machias, Eastport, BHB and possibly BGR. NW winds 5 to 10 kt. Wednesday night into Saturday...Prevailing VFR conditions. N to NW winds 5 to 10 kt.
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&& .MARINE...
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NEAR TERM: A Small Craft Advisory remain in affect through tonight. It has been extended through Tuesday, especially in the outer waters where seas will remain in SCA criteria. Reduced visibility in patchy fog. SHORT TERM: Seas just over 5 ft may necessitate extension of the SCA for outer waters Tuesday night. Otherwise, light winds are expected. Southwest winds on Tuesday night into Wednesday will shift to northerly for Wednesday night into late week. Fog is likely Tuesday night and is expected to move away from the waters with a cold front on Wednesday.
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&& .CAR WATCHES/WARNINGS/ADVISORIES...
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ME...None. MARINE...Small Craft Advisory until 8 PM EDT Tuesday for ANZ050-051. Small Craft Advisory until 2 PM EDT Tuesday for ANZ052.
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&& $$ Near Term...LaFlash Short Term...MCW Long Term...MCW Aviation...LaFlash/MCW Marine...LaFlash/MCW