textproduct: Caribou

WHAT HAS CHANGED

-Increased confidence that the system for Thursday night/Friday should have at most minor impacts.

KEY MESSAGES

1) Strong wind gusts will continue this afternoon, with the strongest gusts across far northern Maine. A few additional power outages are possible.

2) Wind chills ranging from 5 to 15 below zero are expected tonight into Wednesday morning across northern Maine. Frostbite on exposed skin can occur in as little as 30 to 60 minutes in these conditions.

3) A series of weak systems are expected to pass near Maine from Thursday night through Monday. These could bring some light to possibly moderate snow to the area.

DISCUSSION

KEY MESSAGE 1... Strong wind gusts will continue this afternoon, with the strongest gusts across far northern Maine. A few additional power outages are possible.

KEY MESSAGE 1 DESCRIPTION... Surface low pressure across central Quebec will continue to deepen to around 950mb late this afternoon. Northern Maine will be post-frontal with rapidly rising pressures and a steep pressure gradient in place. Forecast soundings generally show steepening low level lapse rates with mixing towards 850mb, where winds are 40-45 kt. Boundary layer average winds around 35 to 40kt will yield frequent gusts in excess of 40mph and occasional gusts to near 50mph. A few additional power outages and instances of tree damage remain possible. Winds will remain elevated overnight, but the strongest gusts to advisory criteria are expected to end around sunset.

KEY MESSAGE 2...Wind chills ranging from 5 to 15 below zero are expected tonight into Wednesday morning across northern Maine. Frostbite on exposed skin can occur in as little as 30 to 60 minutes in these conditions.

KEY MESSAGE 2 DESCRIPTION... Winds will remain elevated overnight with gusts to around 25 to 30mph. Strong cold air advection will continue with air temperatures falling into the single digits above zero across northern Maine. The combination of air temperatures and winds will produce wind chills around 15 below zero in the North Woods, 5 to 10 below zero elsewhere across northern Maine, and around zero to 5 above zero for Bangor and Downeast Maine. While these wind chills will not reach advisory criteria, values this cold can still produce frostbite on exposed skin in as little as 30 to 60 minutes. Patchy icy spots are also possible as any standing water from earlier rainfall freezes.

KEY MESSAGE 3...A series of weak systems are expected to pass near Maine from Thursday night through Monday. These could bring some light to possibly moderate snow to the area.

KEY MESSAGE 3 DESCRIPTION... The first of these systems looks like the weakest of them, as a clipper type system brings its associated cold front through the region from late Thursday night through early Friday afternoon. The models differ on how much, if any measurable precipitation we get out of this system. With the core of the upper level forcing and the surface low passing to the north, expect the precipitation to be more showery in nature than anything else, with accumulations generally around an inch or less, with highest amounts across the St Johns Valley.

The models are in less agreement over the timing/track of the next clipper like system with some guidance bringing it through as early as late Friday/early Saturday, others during the day on Saturday and still others which bring the upper system through dry. For now running with slight chance to chance pops for snow showers across the north and rain/snow showers elsewhere.

There is growing consensus that the third system will be the strongest of the three. Once again, there are differences on track, timing and strength. The general consensus is for a northern stream shortwave trough to approach Saturday night and cross on Sunday, with its surface low passing near Northern Maine. This should result in overrunning snow Saturday night Across the North and a rain/snow mix elsewhere. The coast should change to all rain early Sunday, with the rain/snow mix moving northward during the day on Sunday to all but the North Woods and Northeast Aroostook, which should stay as all snow. The precipitation should then change back to all snow as it tapers off Sunday night. There is still quite a bit of uncertainty as to how far north the rain/snow line gets, and also how much, if any, of the cwa goes to all rain. At this time, there is the potential for up to a moderate snowfall across at least portions of the North before any change over/mixing with rain occurs.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

Today...VFR. A period of MVFR is possible at northern terminals in low ceilings this evening, most likely at FVE. WSW winds 10 to 15 kts with gusts 25-30 kts for southern terminals, and 15 to 20 kts with gusts to 30-40kts for northern terminals.

Tonight...VFR. MVFR possible early at northern terminals. WSW winds 10 to 20 knots with gusts to around 25 knots.

Wednesday...VFR. WNW winds around 10 kts with gusts to 20 kts, decreasing in the afternoon.

Wednesday night...VFR. Light SE winds increasing to around 10 kts.

Thursday...VFR. SE winds G15KT possible.

Thursday night-Friday...MVFR or lower possible, especially in the north. S-SW winds G15-20KT possible.

Friday night-Saturday...MVFR or lower possible. LLWS possible at southern terminals.

Saturday night-Sunday...IFR or lower possible. WNW winds G15-20KT possible late Sunday.

MARINE

A Gale Warning remains in effect for all coastal waters through 6z tonight. Winds decrease after midnight, falling to advisory levels over all waters around 6z. Winds decrease below advisory levels Wednesday morning, but seas will remain at advisory criteria into Wednesday evening. Both winds and seas are forecast to be below advisory criteria later Wednesday night through Thursday. Light freezing spray is expected late tonight into Wednesday morning.

Sub-SCA conditions are expected on all waters Thursday and Thursday night. SCA conditions should return to the coastal ocean waters Friday and the intra-coastal waters Friday night and then remain at a minimum at SCA level through Sunday. There is also a chance for gales on the waters from Saturday night through late Sunday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Wind Advisory until 7 PM EDT this evening for MEZ001-002. MARINE...Gale Warning until 2 AM EDT Wednesday for ANZ050>052.