textproduct: Caribou

WHAT HAS CHANGED

- Increased precip chances slightly for the weak systems both Wednesday and Thursday.

KEY MESSAGES

1) Gusty winds, blowing snow, and cold wind chills likely over the weekend, with the possibility of significant snowfall.

2) Two shots at minor snow accumulation during the day both Wednesday and Thursday.

DISCUSSION

KEY MESSAGE 1... Gusty winds, blowing snow, and cold wind chills likely over the weekend, with the possibility of significant snowfall.

KEY MESSAGE 1 DESCRIPTION... Still substantial uncertainty for the weekend. The setup is quite potent, with a strong upper level low diving southeast through New England most likely a bit west of us and pinching off into a cutoff upper low somewhere off the Northeast coast, with bitterly cold rushing southeast along with it. Some models have upper level heights near record minimums at levels such as 500mb off the Northeast coast. Translation, this is a very volatile setup. As the upper level low pinches off, a surface low could develop as well and rapidly strengthen. The problem is that there is a ton of uncertainty as to where exactly this pinching off of the upper low occurs as well as the strengthening surface low.

We can say with fairly high confidence a few things, such as that colder air will move in at least later Saturday into Sunday, with wind chills likely at least 15 below or colder. We can also say that winds will be pretty gusty from the north/northwest later Saturday into Sunday, probably gusty enough for at least some blowing snow but unlikely to be gusty enough for damage. We can also say with confidence that at least a little snow will fall in the Saturday/Saturday night period.

What we have less confidence in is snow totals. There is a minority of model solutions that set things up just right to where we get heavy snow coupled with strong winds. However, the majority of models keep snow totals fairly minor and have a better shot of heavier snow east of us toward the Canadian Maritimes. How strong the winds are, the amount of blowing snow, and just how cold the wind chills get are all dependent on the track and strength of the system.

KEY MESSAGE 2... Two shots at minor snow accumulation during the day both Wednesday and Thursday.

KEY MESSAGE 2 DESCRIPTION... Two weak systems of interest, the first during the day Wednesday and the second during the day Thursday. Both these system involve fairly decent mid/upper level low pressure centers moving southeast through the area. However, neither system has much moisture to work with, associated surface low pressure will be weak, and there is only slight cold air temperature advection. All this being said, impacts will be minor for both systems.

The first system on Wednesday features a weak surface low developing somewhere near the Downeast coast in the morning. Near this surface low will be the best chance of snow showers, which could actually be locally heavy, as low/mid-level instability and lapse rates are actually pretty impressive. The problem is, there's a lot of uncertainty still where these heavier showers will be. They could stay just out over the waters, could be along the Downeast coast, or could be as far north as about Lincoln. Where these snow showers occur during the day Wednesday, locally up to about 3 inches of fluffy snow could fall. Elsewhere, there could still be a few snow showers around Wednesday, but accumulations will be very minor if any. Not much wind on Wednesday, so although snow showers could be locally heavy, not expecting snow squalls as by definition they require stronger wind.

The second system during the day Thursday appears to be less discriminate on location, with the whole area having a chance of snow showers. Any snow accumulation that does occur should be an inch or less, and many places won't get any. Like Wednesday, wind doesn't appear to be much of a factor with Thursday's snow showers, and like Wednesday, it will easily be cold enough for snow as a precipitation type everywhere.

Made rather significant adjustments to the starting point (National Blend of Models), raising PoPs/QPF, as it is going much too dry which is its typical bias in minor snow events like the ones Wednesday and Thursday.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Monday night - Tuesday night: VFR across all terminals through this evening. Tonight, FEW MVFR cigs across northern terminals could become more numerous, with a chance (30 percent) for BKN MVFR cigs. Greatest chance for MVFR conditions at PQI/CAR, though FVE and HUL may also briefly see MVFR conditions overnight. Cigs scatter out into the early morning hours on Tuesday. N to NW winds 10 to 15 kts late this afternoon to decrease overnight, becoming light and variable through Tuesday and into Tuesday night. VFR conditions continue through the day on Tuesday with mostly SKC, then cigs become OVC late Tuesday night with a trend towards MVFR across all terminals.

Wednesday...Mix of MVFR/VFR. Snow showers possible, best chance at BHB. NW wind 5 kts.

Wednesday Night...Mainly VFR. NW wind 5 kts.

Thursday...VFR/MVFR, with best chance of MVFR in the north. NW wind 5-10 kts.

Thursday night and Friday...VFR/MVFR. WNW 5 kts becoming SSW

Friday Night and Saturday...Very low confidence, but potential for IFR or worse late Friday night into Saturday with snow. Variable winds 10 kts or less becoming NW potentially gusting over 25 kts by late Saturday.

MARINE

Gusts 25 to 30 kts will linger through this evening, prior to winds diminishing overnight. Seas 5 to 8 ft will gradually diminish as well, dropping below 5 ft late tonight. Conditions remain below small craft advisory levels through Tuesday and Tuesday night. Light freezing spray possible tonight.

Likelihood of small craft NW winds Wednesday night, coupled with light freezing spray. Of more concern is Saturday afternoon to Sunday, when gales appear a near certainty, with about a 50 percent chance of storms. Winds will be from the N/NW, and freezing spray is likely to be moderate to heavy.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 7 AM EST Tuesday for ANZ050-051. Small Craft Advisory until 2 AM EST Tuesday for ANZ052.