textproduct: Caribou

SYNOPSIS

High pressure will build south of the area into Tuesday. An occluded front will approach on Wednesday and lift north of the area Wednesday night. Low pressure will track into Quebec on Thursday and continue to our north on Friday. High pressure returns on Saturday.

NEAR TERM /THROUGH TUESDAY NIGHT/

Key Messages -Triple point on occlusion moves into the area Tuesday night

The center in the high pressure system over the Mid Atlantic will move off the coast and over the waters tonight. Clouds will move in ahead of the next system, bringing temps into the 20s across the region. For Tuesday, the high pressure will continue to exit over the waters as the triple point of the occlusion approaches. The warm onshore flow and cloudy skies will bring temps into the 40s.

For Tuesday night, the triple point of the occlusion starts to move into the area. For the early night, the clouds will thicken and winds will become calm. Though offshore flow will continue throughout the night, it will be weak enough for areas south of the Central Highlands to start above freezing. CAD will set up throughout the rest of the night. Areas to the north will remain below freezing. Models, including the NBM, were much more aggressive with the progression of the precip into the area. However, upper air model soundings indicate a strong dry layer in the mid to low levels, mainly in the north. This will hold back the progression of precip into the north for the night. For the south, rain will move in and becoming heavier after midnight. In the late night, the precip will gradually move north. Once the precip has fought past the dry sir, the warm nose ahead of the fronts will allow for some freezing rain, though confidence is low. Other areas will see snow.

SHORT TERM /WEDNESDAY THROUGH THURSDAY/

Main point:

* Slick roads possible early Wednesday morning with a slight chance for freezing rain or drizzle.

Discussion: As the warm front continues to lift northwards, precip will continue to march northwards through early Wednesday morning. A pocket of dry air around 900 mb will delay precip onset across the north, as this layer will need to saturate before measurable precip reaches the surface. This saturation may take long enough that by the time precip begins, warm air will have lifted into the north, resulting in initial precip being plain rain. And if this layer saturates quickly, evaporational cooling may wipe out the weak warm nose signature and lead to an initial precip type of snow. There is a slight chance that just enough saturation will occur aloft without wiping out the warm nose and prior to surface temperatures lifting above freezing, which will give a precip type of freezing rain. In this Goldilocks scenario, freezing rain will be short lived, as a degree difference at the surface and/or aloft could quickly shift the precip type in either direction. Any ice accumulations will be minimal if accumulation occurs at all.

That said, even if all precip falls as plain rain Wednesday morning, surfaces may still be briefly slick, especially any elevated surfaces where temperatures hover around freezing, and this could impact holiday travel early on Wednesday. Later in the day as temperatures warm, plain rain will be the dominant precip type throughout the entire forecast area, and the greatest threat to travel will be isolated ponding in any poor drainage areas.

Precip will taper off Wednesday night into Thanksgiving Thursday as a dry slot enters the area between the triple point low and the parent occluded low. Winds may be breezy with a few rain showers early in the day. Temperatures will be seasonal for this time of the year.

LONG TERM /THURSDAY NIGHT THROUGH MONDAY/

Main points:

* Gusty SW winds on Friday with gusts reaching up to 30 mph. * Convective snow showers across the north on Friday with the potential to briefly but rapidly reduce visibility, and may cause flash freezes in the north.

Discussion: Behind the departing occluded low pressure system, a tightened pressure gradient aloft will generate breezy winds across the forecast area. Southwest winds may gust as high as 25 to 30 mph, and stronger gusts are especially likely in any convective snow showers that develop. Forecast soundings for Friday suggest that there could be small but non-zero CAPE, along with steep low level lapse rates of 7 to 8 C/km. Combined with increasing low to mid level winds, convective snow showers that develop could contain brief, sudden moderate to heavy snowfall that may rapidly decrease visibility. Highs on Friday will lift into the mid 30s, but the potency of these convective snow showers, particularly in the north, may develop flash freezes as well. These ingredients do point to the potential threat for snow squalls on Friday, which could be hazardous to holiday travel.

High pressure returns on Saturday for the weekend, with drier weather but cooler temperatures with highs around freezing Downeast and in the 20s in the north. Winds will gradually decrease on Saturday, but early Saturday morning cold temperatures and lingering winds could lead to wind chills falling into the single digits in the north.

AVIATION /18Z MONDAY THROUGH SATURDAY/

NEAR TERM: MVFR conditions for north terminals and VFR for south terminals for this evening. Then VFR for all terminals tonight and Tuesday. Conditions will decrease Tuesday night to MVFR/IFR in the south early, then to the north later. VFR with possible MVFR conditions most likely will remain for FVE/CAR/PQI for the entire Tuesday night. WSW winds around 5 kts tonight. Tuesday, SSW winds 5-10 kts. Tuesday night, light and variable winds.

SHORT TERM: Wed - Wed night: IFR across all terminals in rain. Winds light and variable becoming S 5 to 10 kts late Wednesday night.

Thurs: Improving to VFR from south to north. Winds SW 10 to 15 kts gusting to 20 to 25kts.

Thurs night - Fri: Mainly VFR, though MVFR/IFR at northern terminals in -SHSN. SW winds 10 to 15 kts gusting 20 to 30 kts Friday afternoon.

Sat: VFR across all terminals. Winds W 10 to 15 kts with gusts 20 to 25 kts, decreasing late.

MARINE

NEAR TERM: Winds and seas will be below SCA levels tonight. Then winds will increase to SCA Tuesday and early Tuesday night. Then decrease to below SCA through Tuesday night.

SHORT TERM: Winds and seas below small craft levels through Wednesday. Conditions increase above SCA late Wednesday night with gusts at or above 25kts and seas above 5 feet. Winds approach gale force Thursday night and remain elevated above 34 kts through Friday. Meanwhile seas increase above 10 feet for the coastal waters on Friday with intracoastal ranging from 4 to 6 feet.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory from 7 AM to 10 PM EST Tuesday for ANZ050- 051.