textproduct: Caribou

WHAT HAS CHANGED

- Have allowed the Small Craft Advisory to expire.

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 denotes fast flow aloft. In general, models do not handle systems as well in a fast-moving flow, so a bit of model spread regarding the timing and strength of individual systems is expected.

A northern stream shortwave will approach Wednesday evening, bringing isolated to scattered snow showers to the north. This shortwave is quickly followed by one or two additional waves, allowing for stronger forcing and weak low-level warm air advection. At the surface, a cold front approaches Wednesday night, then pushes south through the region on Thursday.

The result will be widespread light snow developing across the north early Thursday morning, pushing south into the Upper Penobscot Valley, interior portions of Downeast Maine, and possibly the Bangor region. A rain/snow mix is expected elsewhere across interior Downeast, with all rain across the coast. The rain/snow line will push north during the day Thursday; Downeast Maine, the Bangor/Penobscot Region, and much of the Central Highlands will change to all rain, with a rain/snow mix further north. The St. John Valley and parts of NW Aroostook will stay all snow. Expect 1-3" of snow across most of the north (highest amounts over the St. John Valley and NW Aroostook), with less than an inch elsewhere and little to no accumulation along the coast. This will likely cause impacts to the Thursday morning commute across the north, Upper Penobscot Valley, and northern Washington County. The St. John Valley and NW Aroostook could also see impacts lingering into the Thursday afternoon commute.

Another northern stream shortwave approaches Thursday night and crosses the area on Friday. This results in a wave of low pressure developing Thursday night along the stalled cold front, passing somewhere in the vicinity of Maine on Friday. Solutions range from a Gulf of Maine track to a track across northern Maine. This track difference means a wide spread of potential weather from moderate to heavy snow across the northern two- thirds of Maine (Gulf track) to mainly rain (Northern Maine track). All models agree that precipitation should end by early Friday evening as the surface low pushes into the Maritimes and a strong cold front dives well to the south. At this time, there is too much uncertainty to specify exact Friday impacts for northern and eastern Maine.

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

KEY MESSAGE 2 DESCRIPTION... Canadian high pressure will build in Friday night and Saturday before shifting to the south Saturday night and Sunday. This will allow Friday night and Saturday morning lows to fall into the negative single digits across northern Aroostook, Somerset, Piscataquis, and Penobscot Counties, and from around 0 to 10 above elsewhere. Wind chills will range from 10 to 20 below zero across northern Aroostook, Somerset, Piscataquis, and Penobscot Counties; 0 to 10 below elsewhere; and 0 to 5 above over coastal Downeast. In the zones experiencing wind chills of 10 to 20 below zero, frostbite can occur on exposed skin in 30 to 60 minutes, so preparations should be made to minimize time outside Friday night.

Temperatures on Saturday will struggle to recover, with highs only rebounding into the 20s and lower 30s, roughly 15 to 20 degrees below normal. As the high pushes to the south Saturday night, lows should range from the single digits to near 10 across the north, and in the teens to near 20 elsewhere. While still below normal, this is 10 to 15 degrees warmer than Friday night. Highs on Sunday will moderate further to around 5 degrees below normal as the air mass continues to modify.

AVIATION /14Z TUESDAY THROUGH SATURDAY/

Today...VFR all sites. NW wind around 5 kt becoming SW.

Tonight...VFR. SW wind around 5 kt.

Wednesday...VFR except possibly briefly MVFR in a snow showers over the north during the morning. W wind around 10 kt.

Wednesday night-Thursday: MVFR or lower likely. LLWS possible at southern terminals Wednesday night. Wed night winds light and variable shifting S. On Thursday S-SSW winds gusting 15-20kt.

Thursday night-Friday: MVFR or lower possible, become VFR throughout by early Friday. LLWS possible Thursday night. Winds shifting Thursday night and becoming gusty from the northwest Friday. NW winds 10-15kt gusting 20-30kt.

Friday night-Saturday: VFR. NW winds gusting up to 20kt Fri night becoming W on Sat less than 15kt.

MARINE

Winds will increase to SCA tonight into Wednesday for SW winds gusting up to 30 kt. A few gusts may reach 35 kt late tonight. Seas will be up to 5 ft today, tonight and Wednesday.

SCA conditions expected Wed night through early Sat AM. SW gales possible Thu night. Rain Thurs into early Fri AM may reduce vsby. Fri night into Sat light to moderate freezing spray possible with gusty winds and much colder temperatures. Winds expected to be below SCA conditions this weekend.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...None.