textproduct: Caribou

WHAT HAS CHANGED

- Lowered Saturday AM low temperatures a few degrees and lowered high temperatures for Saturday with a much more sharp Arctic airmass.

- Raised winds/wind gusts for Friday afternoon with stronger mixing.

KEY MESSAGES

1) A period of snow late tonight into Thursday morning could make roads slushy, snow covered and slippery over central and northern areas for the Thursday morning commute. Snow will change to rain from south to north Thursday morning then diminish around midday. Another period of snow and rain is likely Thursday night.

2) Increasing probability of modified Arctic air to spread across the region from Friday night into Sunday night.

DISCUSSION

KEY MESSAGE 1...A period of snow late tonight into Thursday morning could make roads slushy, snow covered and slippery over central and northern areas for the Thursday morning commute. Snow will change to rain from south to north Thursday morning then diminish around midday. Another period of snow and rain is likely Thursday night.

KEY MESSAGE 1 DESCRIPTION... A fast moving shallow wave of low pressure will approach from the Great Lakes late Wednesday night and spread overrunning snow from west to east across the area after midnight into the pre- dawn hours Thursday morning with rain Downeast. Snow will be falling across central and northern areas early Thursday morning likely making roads sloppy and snow covered for the Thursday morning commute. The snow will change to rain over central areas by late morning and diminish in intensity across the north around midday. Roads will just be wet across central areas by late Thursday morning and across the north by around midday Thursday as the precipitation diminishes and moves away to the east.

Another fast moving shallow wave of low pressure will come through Thursday night. This next go-round will be mostly rain over the area with some snow over the far north which may coat roads over the north overnight. Arctic air will begin to surge in following this system early Friday morning. This could produce some icy surfaces for the Friday morning commute as wetness on roads, and any slush across the north, freezes. By late morning Friday most road surfaces should be dry but icy patches may remain on some driveways and walkways.

KEY MESSAGE 2...Increasing probability of modified Arctic air to spread across the region from Friday night into Sunday night.

KEY MESSAGE 2 DESCRIPTION... Canadian high pressure will build across the region Friday into Saturday, gradually settling southward on Sunday before moving offshore Sunday night. This pattern will usher in a return of cold air to end the workweek, followed by a moderating airmass early next week.

Friday will feature non-diurnal temperature trends, with high temperatures occurring in the morning before steadily falling throughout the afternoon. By late afternoon, actual temperatures will drop into the teens across Northern Aroostook, Northern Somerset, and Northern and Central Piscataquis counties. Southeastern Aroostook, Northern and Central Penobscot, and Northern Washington counties will fall into the 20s, while the rest of the forecast area will see temperatures near or in the lower 30s. Coupled with northwest winds gusting 25 to 35 mph, late afternoon wind chills will plunge into the single digits across most of the North, with the exception of northern Penobscot and southeastern Aroostook counties, which will hold in the teens. Meanwhile, Downeast Maine and the Bangor/Penobscot regions will experience late-day wind chills in the 20s.

The cold air deepens Friday night as Arctic air pours into Maine. Using the NOAA Hysplit Backward Trajectory model this airmass developed out of the Beaufort Sea area in the Arctic Ocean. Friday night lows plummet to between 10 below and 5 above zero across the North, and into the mid-single digits to lower teens elsewhere. Brisk northwest winds will drive wind chills down to 10 to 15 below zero across most of the North, and near zero along the coastal Downeast region. Wind chills of this magnitude can cause frostbite on exposed skin within 30 to 60 minutes.

Unseasonably cold conditions will peak on Saturday, with highs running 15 to 20 degrees below normal in the upper teens north with mid to upper 20s south. Overnight lows will be 10 to 15 degrees below normal. Temperatures will moderate sharply Sunday into Sunday night, bringing highs and lows to within 5 to 10 degrees of normal. With relatively light winds expected during this weekend timeframe, wind chills are not expected to produce any significant impacts.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... Today

VFR today with the possible exception of a brief period of MVFR or IFR conditions in snow showers over the far north early this morning. Winds W 10 to 15 kt with higher gusts...diminishing this afternoon.

Tonight...VFR dropping to MVFR this evening then IFR by around midnight. Winds light and variable becoming SE 5 to 10 kt after midnight.

Thursday...LIFR to IFR during the morning then IFR to MVFR during the midday and afternoon. Winds S around 10 kt.

Friday...VFR. NW winds 10-15kt gusting 20-30kt.

Saturday...VFR. W-NW winds 5-15kt.

Sunday...VFR. Brief MVFR vsby/cigs possible due to -SHSN at northern terms. W winds 5-15kt with gusts up to 20kt.

MARINE

A SCA will be up today for W winds gusting up to 30 kt. Winds will drop below SCA this afternoon then increase to SCA late tonight for S winds gusting up to 30 kt. Some gusts on Thursday may approach 35 kt over the offshore waters. Seas 5 to 6 ft today, dropping to 3 ft tonight, then building up to 8 ft on Thursday.

Thursday night winds shift NW and brief lull in SCA conditions for a few hours. As the sun rises expecting SCA wind gusts over the Coastal Waters with intra-coastal waters likely <25kt. Seas generally 4-6ft so an SCA will likely need to remain for waves. SCA for winds/waves expected Fri night into Sat AM. Winds/waves expected to generally be below SCA conditions for the weekend but low end possibility of SCA level waves Sun.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 5 PM EDT this afternoon for ANZ050>052.