textproduct: Caribou

WHAT HAS CHANGED

- High temperatures on Thursday have trended warmer, due to slower timing of the cold front. As a result, there is now a much larger area now expected to become all rain or a rain/snow mix.

- Have extended the Small Craft Advisory for the intra-coastal waters through 2 AM.

KEY MESSAGES

1) Active weather pattern for mid to late week with multiple precipitation chances, below normal temperatures and the potential to impact travel.

2) Increasing probability of modified Arctic air to spread across the region next weekend.

DISCUSSION

KEY MESSAGE 1...Active weather pattern for mid to late week with multiple precipitation chances, below normal temperatures and the potential to impact travel.

KEY MESSAGE 1 DESCRIPTION... An active pattern, means we are in a fast flow aloft. In general, models do not handle systems as well in a fast moving pattern. As expected there is a bit of a model spread in terms of timing/strength of individual systems.

The timing differences start on Wednesday, with the GFS the fastest to bring in/end precipitation, while the ECMWF/CMC Global/NAM/CMC Regional all hold off the bulk of the precipitation until Wednesday night and continues into Thursday. For now, viewing the GFS as an outlier. Based on this, expect a northern stream shortwave to approach Wednesday afternoon, bringing initially some isolated to scattered snow showers to the north.

This shortwave is quickly followed by 1-2 more shortwaves, allowing for stronger forcing and some weak low level warm advection. At the surface, a cold front approaches Wednesday night, then pushes south through the region Thursday.

The result should be widespread light snow developing across the North Wednesday evening, then pressing down into the Upper Penobscot Valley and interior portions of Downeast Maine, and possibly into the Bangor region, with a rain/snow mix elsewhere across interior Downeast, and rain across coastal Downeast Maine. The rain/snow line then pushes north during the day on Thursday with Downeast Maine, the Bangor/Penobscot Region and southern portions of the Central highlands changing to all rain, with a rain/snow mix further north. Maybe the St John's Valley and parts of NW Aroostook stay all snow. The result should be 1-3" of snow across most of the North, with highest amounts over the St John Valley and portions of NW Aroostook, with less than an inch elsewhere, including little or now accumulation over coastal Downeast. This could cause some impacts to the Thursday morning commute across the North, Upper Penobscot Valley and northern Washington County. The Saint John Valley and portions of NW Aroostook could also see some impacts to the Thursday afternoon commute as well.

Another northern stream shortwave approaches Thursday night, then crosses the area on Friday. At the surface, this results in a wave of low pressure developing Thursday night along the cold front that passed to the south on Thursday, then passing somewhere in the vicinity of Maine on Friday. The solutions range from over the Gulf of Maine to going across northern Maine. These differences mean a spread of significant weather from moderate to possible heavy snow across the northern 2/3 of Maine (gulf of Maine track) to mainly rain (low track across northern Maine). All models agree that any precipitation should come to an end by early Friday evening, as the surface low pushes into the Maritime and a strong cold front pushes well to the south. At this time, there is too much uncertainty to specify what, if any impacts will be had to Northern and Eastern Maine.

KEY MESSAGE 2...Increasing probability of modified Arctic air to spread across the region this weekend helping limit ongoing river ice decay.

KEY MESSAGE 2 DESCRIPTION... Canadian high pressure builds in Friday night and Saturday, then to the south Saturday night and Sunday. This will allow for lows Friday night/Saturday morning to fall down into the negative single digits across Northern Aroostook, Somerset, Piscataquis and Penobscot counties. And from around 0 to 10 above elsewhere. Wind chills should range from 10 to 20 below across northern Aroostook, Somerset, Piscataquis and Penobscot Counties, 0 to 5 above over coastal Downeast and 0 to 10 below elsewhere. In the zone with wind chills of 10-20 below zero, frostbite could be caused on exposed skin in 30-60 minutes, so make plans to minimize your time outside Friday night. Highs on Saturday only rebound to from around 20 to around 30 - about 15-20 degrees below normal. With the high pushing to the south Saturday night, lows should be in the single digits to around 10 across the North and teens to around 20 elsewhere. While still below normal, this is 10-15 degrees warmer than Friday night. Highs on Sunday should be around 5 degrees below normal, as the air mass continues to modify.

AVIATION /19Z MONDAY THROUGH SATURDAY/

Rest of this afternoon...VFR/MVFR with isolated to scattered snow showers. Northeast winds 10 to 15 knots with gusts up to around 20 knots.

Tonight...Across northern areas, VFR/MVFR. Isolated to scattered snow showers early. Across Downeast areas, VFR/MVFR with isolated to scattered snow showers early. VFR late. Northeast winds 5 to 10 knots, becoming north/northwest.

Tuesday...VFR. North/northwest winds 5 to 10 knots, becoming west/southwest.

Tuesday night...Generally VFR. Occasional MVFR possible across northern areas late with a slight chance of snow showers. Southwest winds around 10 knots, becoming southwest/west.

Wednesday: VFR with MVFR possible in any stronger snow showers across the North. W winds G15-20KT possible.

Wednesday night-Thursday: MVFR or lower probable. LLWS possible at southern terminals Wednesday night. S-SSW winds G152-25KT possible Thursday.

Thursday night-Friday: MVFR or lower possible, become VFR throughout by late Friday. LLWS possible Thursday night. Winds becoming northwest G15-30kt Friday.

Friday night-Saturday: VFR. NW winds G15-25KT possible.

MARINE

A Gale Warning remains in effect for much of the waters, with the exception of the intra-coastal waters, til 8 PM this evening. Small craft advisory conditions are then expected through the remainder of the night into Tuesday night. On the intra-coastal waters, the Small Craft Advisory has been extended til 2 AM Tuesday. A few wind gusts could approach small craft advisory levels early Tuesday. Otherwise, conditions are expected to be below small craft advisory levels on the intra-coastal waters Tuesday through Tuesday night. Isolated/scattered snow showers early tonight.

SCA conditions are likely on the coastal ocean waters and probable on the intra-coastal waters Wednesday-Thursdsay. Gales area probable on the coastal ocean waters Thursday night-Friday night with SCA conditions likely on the coastal ocean waters. Saturday should see SCA conditions to start on the coastal ocean waters with sub-SCA conditions on the intra-coastal waters.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Gale Warning until 8 PM EDT this evening for ANZ050-051. Small Craft Advisory until 2 AM EDT Tuesday for ANZ052.