textproduct: Caribou

SYNOPSIS

A cold front crosses the area this morning, followed by high pressure building in Monday night. A coastal low approaches from the southwest on Tuesday, passes offshore Tuesday night, then exits into the southern Canadian Maritimes on Wednesday. A cold front then moves in Thursday with high pressure building in for Friday.

NEAR TERM /THROUGH TUESDAY/

Key Messages... 1) Nor'easter likely Tuesday/Tuesday night with significant snowfall possible Bangor and Downeast 2) Snow showers and patchy blowing snow today in Northern Maine

Key Message 1... The precipitation looks to arrive during the day Tuesday from west to east, and should start as mostly snow except as a rain/snow mix or perhaps rain along the very immediate coast. There had been a south shift in the models/ensembles from 24 to 12 hours, which would have meant generally less snow for our area. However, with newer 18z/0z models/ensembles, seeing a shift back north in the track, which would increase confidence in warning-criteria (over 6 inch) snow Bangor and Downeast. Held on to watches for snow rather than issuing warnings, but am concerned with this northward shift. Either way, don't expect warning snow in the north, and the far north may not get any snow at all, but Downeast is another story. For further discussion on the storm, see short term discussion section below.

Key Message 2... A lesser concern than the Nor'easter, but still a concern, is for snow showers right along the cold front this morning. As of 2am, we are in a mild airmass with temperatures around freezing in the north and above freezing along and south/east of I-95. Almost all the precipitation has moved off into New Brunswick. Cold front looks to enter NW Maine around dawn today and progress to Caribou/Presque Isle around 8-9am, then get through the rest of the forecast area by noon. However, the main concern is in the north mainly from Mars Hill north where there may be a line of snow showers with the front. We are not expecting snow squalls as the instability just isn't there, but that doesn't mean there will be no impact. Look for temperatures falling back below freezing and for winds to pick up with and behind the front, gusting up to about 30 mph. The passage of the front could lead to a flash freeze of roads and some blowing snow as well from the existing 2 or so inches that fell coupled with the additional dusting to quarter inch of snow with the front. Added patchy blowing snow to the forecast for the open areas of Aroostook County. Most of the blowing snow should be with the front itself this morning, but a little blowing and drifting snow could linger through the day. Winds ease significantly into this evening, with a quiet but very cold night in store Monday night as high pressure builds overhead.

SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/

Key messages -Noreaster may bring warning snowfall to interior Downeast and the coast -Cold temps Tuesday Night with wind chills near zero degrees

For Tuesday night, models have become more consistent with the track of the Noreaster. Recent model runs indicate a shift north, which could cause a few factors to change. First, snow ratios could be lower especially in the south with some warmer temps. Second, NE winds could cause a model bias to warmer temps, which could cause model forecast snow amounts to be low. Third, snow amounts in the north could be more with the QPF shifting north. Thus, confidence is still low enough to leave the Winter Storm Watch in the forecast until the CAMs can give more consistency.

Temps are expected to reach into the teens in the north and 20s in the south for Tuesday night. As the storm moves over the Gulf of Maine, tightening pressure gradients should cause N winds to become breezy. This with early morning clearing skies, wind chill values could reach near zero degrees.

For Wednesday, brief and weak surface ridging should clear out skies and decrease winds. Temps should be in the 20s. For Wednesday night, a cold front should approach the region, increasing clouds and shifting winds from the south. Temps should be in the teens for the region.

LONG TERM /THURSDAY THROUGH SUNDAY/

Key messages -Snow squalls possible on Thursday -Very cold temps Thursday night with wind chills below -20F

The cold front is expected to move through the area on Thursday. The concern with this system is the increasing instability along the front. Upper air models soundings show enough SBCAPE and elevated CAPE, lapse rates, and negative Theta E to justify snow squalls developing in the afternoon. The question will be if strong enough winds will mix down throughout the day. Once the front passes Thursday night, very cold arctic air moves into the area dropping temps into single digits below zero. This coupled with gusty NW winds could drop wind chills into teens to 20s below zero. High pressure moves into the area Friday. The models lose consistency for the weekend with another storm possible. Decided to leave the NBM slight chance precip.

AVIATION /12Z MONDAY THROUGH FRIDAY/

NEAR TERM: Expect generally MVFR conditions at northern terminals behind a cold front that is moving through FVE around 12z and around CAR/PQI around 14z. Northern terminals should eventually improve back to VFR midday or early afternoon. VFR at southern terminals (BGR/BHB) today. W/NW winds pick up after about 14z with gusts to 25 kts at all sites. Winds ease significantly tonight, with VFR areawide. For Tuesday, look for VFR to start and then decreasing to MVFR and eventually IFR especially at southern terminals, with snow or rain/snow developing. Variable winds less than 10 kts during the day Tuesday.

SHORT TERM: Tuesday night...MVFR/IFR in snow. S 5-10kts becoming NNE 5-15kts Tuesday evening, gusts to 20kts south.

Wednesday-Wednesday night...Mainly VFR. NNW 5-10kts becoming SSW 5-10kts Wednesday evening.

Thursday...MVFR/IFR tempo LIFR in snow showers. SSW 5-15kts, gusting to 20-25kts.

Thursday night-Friday...Mainly VFR, though MVFR possible north. W 5-15kts, gusts to 20kts.

MARINE

NEAR TERM: Low end westerly gales are likely today. Seas around 11 ft early this morning, subsiding to 6 ft later today. Winds and seas continue to diminish substantially through late tonight, ending up well below small craft. However, winds/seas begin to pick up late Tuesday as the next storm moves in.

SHORT TERM: Gales possible Tuesday night into Wednesday. Winds increase toward SCA levels Wednesday night with gales once again behind cold front on Thursday. Winds diminish late on Friday. Seas increase above 5ft Wednesday morning, remaining elevated through Friday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Winter Storm Watch from Tuesday morning through Wednesday morning for MEZ011-015>017-029>032. MARINE...Gale Warning until 4 PM EST this afternoon for ANZ050>052.