textproduct: Caribou

WHAT HAS CHANGED

- Update for 12z aviation discussion

- Lowered high temps on Friday using NBM10th percentile and NAM to account for stronger winds off the Bay of Fundy.

- Changed precip chances Friday night into Saturday to move west to east gradually, along frontal boundary.

- Added patchy fog along coast Friday night.

- Keeping thunder to the west Friday night, based on frontal passage.

KEY MESSAGES

1) Warm and increasingly humid conditions through Friday, with the highest temperatures focused inland.

2) Showers this evening and persist into the weekend.

DISCUSSION

KEY MESSAGE 1...Warm and increasingly humid conditions through Friday, with the highest temperatures focused inland.

KEY MESSAGE 1 DESCRIPTION... The overall 500mb ridging remains over the area with very warm 850mb temperatures into Friday. The ridge becomes contaminated allowing for the return of clouds and showers but the airmass remains very warm. Although not record breaking it will be uncomfortable for some with minor to moderate heat risk mainly impacting the most vulnerable groups. The focus of the hot temperatures shifts north into Northern Maine where highs will top out in the upper 80s to around 90F for the Central Highlands northward to St. John Valley. Expecting mid to upper 70s Downeast thanks to a wind off the Gulf of Maine and Bay of Fundy with low to mid 80s around Bangor to Topsfield. A touch of the muggies today with dew points climbing into the low to mid 60s so it will feel humid. Friday the 925-850mb airmass is still warm but significant cloud cover, showers and SE winds off the Bay of Fundy will result in a little bit lower highs. Low to mid 80s for Northern Maine, Central Highlands to Bangor Region with 60s-70s in the Downeast with the coldest temps near the shoreline. It will be pretty muggy on Friday with dew points in the 63-68F range for most areas with some 70F readings in the Bangor region.

KEY MESSAGE 2...Showers this evening and persist into the weekend.

KEY MESSAGE 2 DESCRIPTION... Shortwave moves over the region today, bringing some moisture and instability into the region. Decent low-level lapse rates, but southeast flow provides a marine layer over eastern Maine, stabilizing the surface. There is some mid-level instability, but mid-level lapse rates are very poor. Without strong forcing, not expecting too much in terms of storm development. Could be a few thunderstorms in the west, such as northern Somerset and western Piscataquis, since the marine layer will be confined to the windward side of the mountains.

On Friday, weak ridging moves in over the region as a cold front creeps in from the west, with some increasing instability. Chance for some showers and an isolated thunderstorm to develop, mainly confined to the western regions. Stable southeast flow over Downeast should keep should showers north of Bangor.

Friday night into Saturday, cold front moves closer in from the west. Could be some thunderstorms that stay off to the west overnight. Diurnal heating decreases, but forcing from the front could help develop an isolated storm and continued showers. During the day, showers and isolated storms could move over Northeastern Aroostook, diminishing by nighttime.

AVIATION /12Z THURSDAY THROUGH MONDAY/

Today... VFR Aroostook terminals with BKN mid-deck expected.

Mainly VFR at BGR this morning, cannot rule out a very brief IFR/MVFR restriction. BHB will see IFR cigs gradually improve to 2500ft around 19z. Winds become south around 5 kt as sea breeze develops at Downeast terminals.

Tonight...Mainly VFR before diminishing to MVFR late at Aroostook terminals. Winds remain light and variable around 5 kt or less.

MVFR at BGR, potentially dropping to IFR in low cigs/vsbys after 06z tonight. BHB IFR, possibly LIFR after 06z. Winds light and variable.

Friday Night-Saturday: MVFR, or lower, due to rain showers. Slight chance for thunder at KFVE, and patchy fog overnight at KBGR/KBHB. SE winds G15KT possible Friday evening. Winds shift S/SW by evening.

Saturday Night: VFR. Light S winds.

Sunday-Sunday Night: MVFR, or lower, due to rain showers and potential thunderstorms in the morning and day. S winds with gusts 15-20KT possible Sunday. LLWS possible Sunday night. Monday: MVFR in rain showers. S winds, shifting W/SW by afternoon, with gusts 15-20KT possible.

MARINE

Below SCA conditions through the weekend with winds generally 15kt or less and seas 2-4ft or less. Fog and showers may reduce vsby over the waters through Friday. Another round of fog possible Friday night. There is the potential for some showers over the waters Friday night into Saturday, and again on Monday. Wind gusts will approach 25kt Sun night into Mon AM especially across the outer waters 25-60nm.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...None.