textproduct: Caribou

SYNOPSIS

Low pressure continues moving north today. Low pressure develops along the coast tonight, then strengthens as it moves east into the Canadian Maritimes Thursday. Additional weak disturbances rotate through the area into the weekend.

NEAR TERM /THROUGH THURSDAY/

7AM Update: Extended the SCA and Gale Warning until 18z today based on obs and forecast data. The freezing spray advisory was allowed to expire.

Key Message 1: Cold today with lingering light snow and patchy blowing/drifting snow today across far northern Maine.

Key Message 2: Snow will impact New Years Day travel with the greatest accumulations expected across Downeast Maine starting late tonight through New Years Day.

Discussion: A strong 955mb low pressure system over northern Quebec will continue to direct Arctic air into the area and cause gusty winds today. While conditions will not be as bad as yesterday, some patchy blowing snow is still possible across open areas today as the cold temperatures make it easier for snow to be lofted. Pockets of PVA collocated with ample 700mb moisture across northern Maine and the Central Highlands will lead to light snow and flurries through the day, with some light accumulation expected over upslope west facing slopes in the North Woods. The pressure gradient will relax tonight, but increasing clouds are expected ahead of the next system.

A vigorous shortwave trough will cross the eastern Great Lakes this evening, progressing into New England after midnight before becoming negatively tilted Thursday morning near the NH/ME border. A weak surface low will quickly transition to the coast and strengthen during the day Thursday, resulting in potential for significant snow accumulations across Downeast Maine, especially along the coast. Guidance, including ensembles and the NBM, continues to shift stronger and further NW with the low and snowfall, showing a potential deformation zone setting up as far north as eastern Aroostook County Thursday evening. A Winter Storm Watch has been issued for Downeast Maine where confidence is highest, but an expansion of winter weather headlines may be needed in subsequent updates today if trends continue. In some stronger scenarios as shown on a few 0z EPS members, wind gusts in excess of 45mph are possible with falling and blowing snow for eastern Aroostook County. The greatest period of impact appears to be during the day Thursday for Downeast Maine, and Thursday evening for Aroostook County.

SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/

Key Messages... *Potential for significant snowfall in northeastern Maine Thursday night, with chance of blowing snow *Very cold temperatures and wind chills through end of the week

Key Message 1... Shortwave disturbance causing snow showers throughout the Downeast and eastern Maine region continues to curve northwest into New Brunswick. Additional disturbances and vorticity swings in behind this original shortwave, further providing instability for some continued showers. Decent pressure gradient keeps gusty winds throughout the night, and with the recent snowfall having relatively high SLRs, blowing snow could occur, significantly reducing visibility. High wind gusts could also cause isolated power outages.

Depending on the track this system takes, and how much additional instability feeds into the low, there could be a potential for either a few inches, or significant, accumulating snow, predominantly in the north. Majority of the models do have the low center going vertically up along the eastern border of the state, but how it swings northwest will determine how much additional snowfall the north will receive. The NAM and ECMWF have the snowiest solutions currently, with tracks moving close to the eastern border and swinging just to the north in New Brunswick, wrapping around decent amounts of moisture that result in the north getting over 6 inches Thursday night. The GFS and NBM seem to have the low continue more northward, which would only give a few inches of snowfall to the north. Currently went with the north getting an a few inches until there is more confidence in model track trends. There is relatively decent confidence that additional snow will fall overnight, but pinpointing the actual totals is the forecast challenge with this system. There is a dry slot at 850mb overnight, but with instability, potential for a deformation zone, and plenty of low level moisture, there could still be decent snowfall. General trend so far has been favoring a northwest trend for the low, which is going to continue to increase snowfall accumulations. Continue to monitor the forecast as CAMs better pick up on this system.

Key Message 2... As the broad longwave trough parks over Canada through most of the week, cold arctic air is funneled into New England region, resulting in below average daytime highs, and bitter overnight wind chills. Thursday night will be especially cold as winds ramp up, with the ambient temperatures in the north potentially dipping 10-15 below, and at or around 0 degrees in the Downeast region. Wind chills in the north could reach 20 below overnight, and 10 below Downeast. Similar cold temperatures on Friday night, with the north seeing wind chills down to 20 under, and 10 under Downeast.

LONG TERM /SATURDAY THROUGH TUESDAY/

Key Messages... *Cold temperatures through the weekend *Potential for system early-to-mid week

Key Message 1... Cold temperatures linger throughout the weekend, as low pressure to the north parks in central Canada, continuing to push cold air masses towards Maine. Daytime highs generally staying in the single digits to low teens in the north, and the teens to 20s Downeast. Overnight lows around 10 below in the north, and generally in the single digits Downeast. Wind chills in the negative 20 range is possible in the north overnight Saturday and Sunday.

Key Message 2... Next chance for precipitation could be early next week, as a surface low moves towards the state. Very high model uncertainty in the low track. The GFS has the low moving over Maine mid-week with potential for decent snowfall. The ECMWF, however, has the low slides north of the region mid-week. Overall, the GFS now has a snowier solution. The overall trend to note here is that there could be a low pressure system move towards Maine bringing a chance for precipitation, but the track and intensity are all over the place. Continue to monitor the forecast for updates.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

NEAR TERM: Through Today: MVFR at northern Aroostook County terminals with occasional -SN. Cannot rule out brief periods of IFR visibility. VFR for the rest of the area. SW winds around 10 kts gusting to 20 kts.

Tonight: VFR, becoming MVFR/IFR late along the coast with -SN developing. Light winds.

Thursday: IFR/LIFR developing with snow. N winds strengthen through the day, shifting slightly NW late and increasing to 10 to 15 kts with gusts to 25 kts. Higher gusts are possible in the evening in some scenarios, especially for eastern areas.

SHORT TERM: Thursday Night...Very uncertain due to track of storm, predominantly for northern terminals. Snowfall is expected, but totals and intensity are subject to change. Currently, anticipating MVFR/IFR at northern terminals, with periods of LIFR due to blowing snow reducing visibility. VFR/MVFR at southern terminals. NW wind 10 kts with gusts to 30 kts in the north, and 25 kts at southern terminals.

Friday through Sunday...Mainly VFR. Generally W winds 5-15 kts. Gusts up to 25 kts possible during the day Friday and Saturday.

MARINE

NEAR TERM: Winds will decrease to advisory levels this morning over the outer waters and waves will decrease below advisory levels on the intracoastal waters. Waves of 5 to 9 feet and gusts to around 30 kts will continue over the outer waters during the evening. Winds and seas briefly fall below advisory levels over all of the waters late tonight before increasing towards Gales again on Thursday. There is higher than normal uncertainty in waves and winds Thursday due to uncertainty in the track of a coastal low, however confidence was still enough for a Gale Watch. Light freezing spray is forecast this morning as conditions become less favorable for freezing spray.

SHORT TERM: Gale Watch out for Thursday night, with increasing wind and seas. Winds gradually fall below SCA criteria during the day on Friday. Moderate freezing spray over all waters Thursday night. Snow early Thursday night. Winds from NW Thursday night, shifting west by Friday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Winter Storm Watch from late tonight through Thursday evening for MEZ016-017-029-030. MARINE...Gale Warning until 1 PM EST this afternoon for ANZ050-051. Gale Watch from Thursday afternoon through late Thursday night for ANZ050-051. Small Craft Advisory until 1 PM EST this afternoon for ANZ052.