textproduct: Caribou

SYNOPSIS

An Arctic cold front crosses the region today. High pres builds across the region Fri into Sat. A cold front crosses the region Sun. High pres builds toward the region Mon and crosses the region Tuesday.

NEAR TERM /THROUGH FRIDAY/

Main Points: * Snow squall potential today may cause hazardous travel conditions for the evening commute * Very cold wind chills tonight, with a Cold Weather Advisory for the North Woods into the Central Highlands

Discussion: An arctic front will approach from the west this morning, crossing through the forecast area through the daylight hours. A prefrontal trough may lead to some early snow showers ahead of the FROPA. That said, the most impactful snow showers will occur along the boundary itself, which will provide the lift necessary to kick off the convective shower development. Weak but nonzero CAPE of 20 to 40 J/kg will fuel these showers, and steep lapse rates around 8 C/km will help mix increasing winds aloft due to a tightening pressure gradient to the surface. Together, these ingredients may lead to scattered moderate to heavy snowfall in any showers that develop. There exists the chance for snow squall development as well, particularly later in the day as the front approaches the eastern border and diurnal heating peaks and winds aloft increase further, increasing the potential for surface gusts to exceed 30 mph. Finally, temperatures around freezing ahead of the cold front will rapidly drop into the single digits by this evening. This quick turn in temperatures could lead to flash freezes, further impacting travel impacts heading into the evening commute today.

Strong cold air advection behind the arctic front will lead to winds 15 to 20 mph and gusts as high as 30 to 40 mph, while temperatures dip below zero. Combined, wind chills will approach 20 to 30 below zero in the north, and 10 to 15 below zero Downeast. A Cold Weather Advisory has been issued for the North Woods down into the Central Highlands for these very cold wind chills. Thankfully, temperatures will begin to climb once more Friday morning, and though high temperatures may only lift into the low to mid teens during the day on Friday, winds will gradually decrease and wind chills will quickly drop off into the daylight hours.

SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/

Key Messages -Cold Friday night with lows in the single digits

High pressure remains overhead Friday night with the arctic airmass expected to persist over the area. This should result in the continuation of anomalously cool temperatures around 10 degrees below normal. With the high centered over us, the lack of a pressure gradient should keep winds light and thus wind chills are not a concern.

High pressure gradually exits to the east on Saturday and with it much of the cold air. Temperatures should only be a few degrees below normal Saturday. A weak shortwave approaches from southern New England and is likely to produce some scattered rain showers over the waters and snow showers over the Downeast area during the day. Meanwhile, a cold front will be approaching from Canada and may produce some snow showers over the north late Saturday night.

LONG TERM /SUNDAY THROUGH WEDNESDAY/

Key Messages -Arctic air returns Sunday night through Tuesday night with temperatures well below normal

The cold front reaches the region Sunday morning and may produce some snow showers over the north early in the day. However, models are not very optimistic on precipitation chances due to a lack of moisture and a rapidly weakening front.

Behind the front, a fast moving shortwave may bring some light snow showers to the area Sunday night. Meanwhile, prevailing NW flow is likely to bring another shot of cold arctic air which will send temperatures down to at least the single digits Sunday and Monday night. Luckily, winds should be relatively light so not expecting a major wind chill concern.

Temperatures begin a warming trend Tuesday which will continue into mid week. High pressure prevails Tuesday with the chance for another system Wednesday but models are expressing uncertainty in how that would evolve.

AVIATION /06Z THURSDAY THROUGH MONDAY/

NEAR TERM: Generally VFR conditions will last through the day today, into tonight, and through the day on Friday. Brief periods of IFR/LIFR possible during the day today in snow showers, some of which may be squalls containing heavy squalls. Most likely time for LIFR in SHSN is after 13z and prior to 18z, and these conditions are most likely over northern terminals, though there remains a chance for moderate to heavy snow showers at all terminals today. SW winds 5 to 10 kts shift NW behind a cold front through midday, increasing to 10 to 15 kts and gusting 25 to 35 kts through tonight. Winds decrease, becoming SW 5 to 10 kts by Friday afternoon.

SHORT TERM:

Friday night...VFR. Light SW winds early becoming light and variable.

Saturday...VFR early, then VFR/MVFR with snow showers, especially for southern terminals. S/SE winds around 5 knots.

Saturday night...VFR/MVFR with chance snow showers early. Light and variable winds.

Sunday...VFR/MVFR with isolated snow showers northern terminals. W/NW winds 5 to 10 knots.

Sunday night...VFR/MVFR with chance snow showers. NW winds 5 to 10 knots.

Monday...VFR. W/NW winds 5 to 10 knots.

Monday night...VFR. W wind around 5 knots.

MARINE

NEAR TERM: A gale warning remains in effect beginning this afternoon as gusts increase to 40 to 45 kts and seas increase to 6 to 9 ft. Conditions improve to below small craft advisory criteria by midday Friday.

SHORT TERM: Winds decrease from small craft advisory criteria Friday night. Winds and seas below small craft advisory criteria through Sunday. Winds increase to above SCA criteria Sunday night through Monday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Cold Weather Advisory from 9 PM this evening to 8 AM EST Friday for MEZ001-003-004-010. MARINE...Gale Warning from 3 PM this afternoon to 7 AM EST Friday for ANZ050>052.