Marine Weather and Tide Forecast for Southwest Harbor, ME

KEY MESSAGES
1) Falling wind chills through tonight, increasing the risk for hypothermia or frostbite to exposed skin.

2) Coldest air of the season Friday night through Monday, with extremely dangerous wind chills.

3) Light snow Wednesday night, mostly Downeast.

DISCUSSION
KEY MESSAGE 1...
Falling wind chills through tonight, increasing the risk for hypothermia or frostbite to exposed skin.

KEY MESSAGE 1 DESCRIPTION...
As arctic air continues to rush into the region today with building high pressure, temperatures will begin to drop. Though air temperatures may only fall into the single digits above zero Downeast, and single digits below zero across the north, it is the increasing winds that will create the most impact. Wind chills will fall below zero across the north this afternoon, and below zero Downeast this evening. Minimum wind chills across the north tonight could drop to around 20 below, though a few colder locations may touch 25 below shortly before daybreak Wednesday morning. Bangor and the Downeast region may see isolated areas reach 10 below zero before wind chills improve into the day on Wednesday.

KEY MESSAGE 2...
Coldest air of the season Friday night through Monday, with extremely dangerous wind chills.

KEY MESSAGE 2 DESCRIPTION...
An extremely potent cold outbreak is in store. The big push of cold air comes in Friday night, and the most dangerous part of the cold outbreak comes late Friday night through Saturday night. This is when the airmass overall will be the coldest, and it will also be quite breezy with sustained winds 10-20 mph with some gusts to 30 mph. This will likely lead to wind chills around 35 below in the north (and possibly even colder), and to about 25 below Downeast. Even during the day Saturday, the wind chills only get up to around 25 below in the north and up to around 15 below toward the coast, and air temperatures should stay below zero in the north and only barely above zero toward the coast. Winds ease slightly into Sunday and Monday with a very slight warming trend. That said, if winds can calm down in the latter part of the cold outbreak, Sunday night could be extraordinarily cold. The so-called warming trend toward Monday entails highs zero to 5 above in the north and 10 to 15 above Downeast. The bottom line is that confidence is high in a long duration cold outbreak late Friday through Monday that will be of the magnitude we see only once every few years. Impacts in cold outbreaks like this in the past include frost quakes and exploding trees, and obviously frostbite that can occur very quickly.

We cannot rule out a few snow showers or perhaps snow squalls Friday and Friday night as the bitter cold air moves in, but do not think that will be nearly as big of a story as the extreme cold. It appears through early next week, most of the precipitation will remain south of the area.

KEY MESSAGE 3...
Light snow Wednesday night, mostly Downeast.

KEY MESSAGE 3 DESCRIPTION...
A weak system moving through from west to east is likely to bring some light snow to the area, with the better chances of a few inches being Downeast. This looks most likely to be a 1-3 inch storm, with perhaps a spot or two Downeast reaching 4 inches. The north should only get around an inch. Precipitation could mix with rain near the coast at the tail end late Wednesday night.

AVIATION /06Z TUESDAY THROUGH SATURDAY/
Today...VFR conditions continue across all terminals today with mostly clear skies. LLWS early this morning prior to mixing out past 11z when gusts begin mixing to the surface. W to WSW winds 10 to 15 kts with gusts 20 to 30 kts through the day today.

Tonight...VFR conditions continue, while SW winds decrease to 5 to 10 kts.

Wednesday...VFR early, with skies gradually becoming OVC and then cigs falling towards low end MVFR or possibly IFR by early Wednesday evening as snow approaches from the west. SW winds 5 to 10 kts.

Wednesday Night...IFR Downeast including BHB/BGR with possible snow, and generally MVFR or VFR elsewhere. S wind 5 kts.

Thursday and Thursday Night.. MVFR/VFR north, and generally VFR south. W/SW wind 5-10 kts with gusts to 20 kts during the day Thursday.

Friday and Friday Night...W wind 10-15 kts with gusts to 25 kts. MVFR/VFR north and VFR south.

Saturday and Saturday Night...Mainly VFR with W wind 10-15 kts with gusts to 25 kts Saturday, decreasing to 5-10 kts Saturday night.

MARINE
Gale conditions continue on the coastal waters through the day today, with gusts 35 to 40 kts and seas 8 to 12 ft. Intracoastal waters will continue to see small craft advisory criteria, with gusts 25 to 30 kts and a few gusts to 35 kts possible, especially through early this morning, and seas 3 to 5 ft. Light freezing spray is expected beginning around sunrise and lasting through tonight. Winds will begin to decrease overnight, falling below gale conditions on the coastal waters and below SCA criteria on the intracoastals by Wednesday morning. However, winds will begin to pick up once more late Wednesday afternoon.

Gales likely to begin Wednesday night, and likely persist until about Saturday night at least for the outer waters, though the inner waters could be small craft at times. Moderate to heavy freezing spray expected Friday night through Sunday. Seas will be highest at around 10 ft Wednesday night, then generally hover around 4-8 feet through Friday night, then decrease to 3 to 5 feet for the weekend.

CAR WATCHES/WARNINGS/ADVISORIES
ME...None.
MARINE...Gale Warning until 1 AM EST Wednesday for ANZ050-051.
Small Craft Advisory until 1 AM EST Wednesday for ANZ052.