textproduct: Caribou

WHAT HAS CHANGED

-Weekend system continues to slow. Saturday has better chance for heavier rainfall and thunderstorms.

KEY MESSAGES

1) Hot and fairly muggy through the weekend.

2) Scattered showers and thunderstorms late this week. Some severe storms are possible.

DISCUSSION

KEY MESSAGE 1...Hot and fairly muggy through the weekend.

KEY MESSAGE 1 DESCRIPTION... Similar temperatures to today expected on Thursday, then slightly less hot Friday through Sunday in the north, but just about as hot for the Bangor region and Downeast. Thursday will be muggier than today with dewpoints increasing slowly.

Friday will feel muggier with dewpoints nearing 70. At some point, we could approach heat advisory criteria of heat indices of 95, most likely on Friday and in the Bangor region. In addition nighttime lows are quite mild from Thursday night into the weekend. There will be a bit of relief from the heat near the coast mainly as afternoon sea breezes develop, though any of the days could get quite hot before the sea breeze kicks in.

KEY MESSAGE 2...Scattered showers and thunderstorms late this week. Some severe storms are possible.

KEY MESSAGE 2 DESCRIPTION... Low pressure system approaches from the northwest, moving into New Brunswick. Associated cold front is continuing to trend slower, as it approaches Friday night, through Maine by Saturday evening. General trends is pointing towards the heavier rainfall falling on Saturday. There is plenty of instability ahead of the cold front. NAM shows around 1,500 - 2,000 J/kg of CAPE, good low level lapse rates (roughly 8C/km), and plenty of precipitation for Friday evening and Saturday afternoon into evening. Soundings are moist, with classic long and skinny CAPE throughout most of northern and eastern Maine. PWAT values around 1.8, with some models hinting at almost 2.0" on Saturday, which is around the 90th percentile, approaching the 1.9 daytime maximum value Friday evening, and the 1.7" record Saturday. Keeping the threat of thunder inland, as a seabreeze off of the cool Gulf of Maine waters should stabilize and keep daytime high temperatures on the lower side along Downeast Maine coastline on both days. Storm motions based on Corfidi vectors seems to be moving fast enough to keep flash flooding at bay, but will need to see this evolves as the regional models and CAMs pick up on the system and preexisting environment. Bottom line up front: Saturday seems to be more favorable for heavier rainfall, and more expansive thunderstorms.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

Tonight...VFR. Cannot rule out MVFR/IFR river valley fog late. Light SSW winds.

Thursday...VFR. WSW winds 5-10kts.

Thursday night...Mainly VFR. Another round of MVFR/IFR river valley fog. BHB may also be impacted by fog late. Light W winds.

Friday...Mainly VFR with possible MVFR/IFR for north terminals in isolated showers and thunderstorms. W winds 5-10kts.

Friday night-Saturday...MVFR/IFR in showers with possible thunderstorms Saturday afternoon. Light winds overnight, becoming S at 5-10kts on Saturday.

Saturday night-Sunday...MVFR/IFR in showers early Friday night and Saturday afternoon. W winds 5-10 kts.

Sunday night-Monday... VFR overnight, and MVFR possible in showers Monday. W at 5-10 kts.

MARINE

Winds and seas below small craft levels for all waters through the weekend. Seas will generally range between 2 and 4ft throughout the period. Chance for rain and thunderstorms on Saturday.

CAR WATCHES/WARNINGS/ADVISORIES

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