textproduct: Caribou

WHAT HAS CHANGED

-Potential for snow Downeast on Tuesday, with a chance for some heavier showers in the afternoon.

KEY MESSAGES

1) Potential for heavy snow showers persists into tonight in northern Maine. Could result in periods of reduced visibility and slick travel.

2) Cold temperatures and light snow Tuesday night.

3) Low RHs expected Wednesday which may lead to increased fire weather concerns in areas where no snowpack exists.

DISCUSSION

KEY MESSAGE 1...Potential for heavy snow showers persists into tonight in northern Maine. Could result in periods of reduced visibility and slick travel.

KEY MESSAGE 1 DESCRIPTION... Lingering instability from departing low pressure, and shortwave, result in some snow showers throughout the north this evening. Northwesterly flow and decent low-to-mid level lapse rates results in some Laurentian plumes off the St. Lawrence river. CAMs continue to pick up on these plumes occurring this evening into late tonight. Snow squall parameter ingredients look favorable for good lift, but not anticipating winds to reach squall criteria. These plumes could cause periods of reduced visibility and slick travel. Snow shower chances decrease after midnight tonight. Not much in accumulations expected due to short duration of showers potential for up to half an inch in localized locations.

KEY MESSAGE 2...Cold temperatures and light snow Tuesday night.

KEY MESSAGE 2 DESCRIPTION... High pressure from the west builds in, with colder air settling over the region. Overnight lows tonight in the single digits to teens in the north, and low-to-mid 20s Downeast. Temperatures a little colder Tuesday night, especially with skies expected to clear out. Overnight lows in the single digits to low teens in the north, and low-20s Downeast. Thankfully, both nights do not have much wind, keeping apparent temperatures above zero at least. Remember to bundle up if spending long periods of time outdoors.

Shortwave moves in on Tuesday afternoon as well, moving just south of Nova Scotia. It brings a chance of light snowfall, mainly confined Downeast, and generally under an inch in accumulations. Decent lapse rates indicate there could be periods of heavier showers.

KEY MESSAGE 3...Low RHs expected Wednesday which may lead to increased fire weather concerns in areas where no snowpack exists.

KEY MESSAGE 3 DESCRIPTION... Dry snowfree grounds Downeast to Bangor Region, low RHs, light winds, and mostly sunny skies may lead to some increased fire weather concerns Wednesday.

On Tuesday, high pressure building in from the west will result in subsidence across the area with a mix of sun and clouds allowing for mixing up to 800mb. With ample dry air aloft, this is likely to result in dry conditions near the surface with RH around 30-35%, especially in the Bangor region and Upper Penobscot Valley. Elsewhere, 40-45% RHs. Questions still remain as to just how low RHs will drop depending on if a weak clipper moving just offshore brings any precipitation to southern areas.

High pressure slides to the south of Maine Wednesday resulting in W-SW flow across the area under a strong subsidence inversion with ample dry air aloft. Deep mixing up to 800mb combined with mostly sunny skies, especially further south, should contribute to very low RHs, likely below 23-28%. Elsewhere generally 35-40% across the North from Moosehead Region to Baxter Region northward to the St. John Valley. Winds will not be that strong generally 5-10mph with occasionally gusting 15 to 20 mph especially across the terrain.

AVIATION /19Z MONDAY THROUGH SATURDAY/

Tonight...Generally VFR. Could be periods of MVFR/IFR at northern terminals in periods of snow showers. Winds from the NW 5-10 kts. Gusts up to 15-20 kts possible earlier in the evening.

Tuesday...Generally VFR in the north. Potential for MVFR in southern terminals with some snow showers. Could be brief periods of heavier snow showers. Winds from the NW 5-10 kts. Tuesday night...VFR as snow showers move out of the region. NW winds at 5-10 kts.

Wednesday through Thursday...VFR. West/southwest winds 10 to 15 knots with gusts up to 20 knots Wednesday. South/southwest winds 5 to 10 knots Wednesday night. South winds 10 to 15 knots with gusts up to around 20 knots Thursday.

Thursday night...VFR/MVFR north. VFR Downeast. South winds around 10 knots.

Friday...VFR/MVFR north with a chance of showers. Across Downeast areas, a slight chance of showers and MVFR late. Otherwise, VFR. South winds 10 to 15 knots with gusts up to 20 knots.

Saturday...VFR. AM showers possible. W-NW winds 5-15kt.

MARINE

Conditions below Small Craft criteria through Tuesday. Chance for some Small Craft conditions starting Tuesday night. Chance of snow Tuesday. Winds from the W/NW, shifting to the E by Tuesday.

SCA conditions Tuesday night. Conditions below SCA levels Wednesday/Wednesday night. Another round of SCA conditions Thursday into Thursday night. A chance of snow early Tuesday night.

CAR WATCHES/WARNINGS/ADVISORIES

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