textproduct: Caribou

SYNOPSIS

Low pressure crosses the area tonight and moves into the Canadian Maritimes Thursday. High pressure builds in Saturday. Low pressure passes south of the area Sunday night.

NEAR TERM /THROUGH THURSDAY NIGHT/

5PM Update (MS): Expanded the Winter Weather Advisory again, this time to northern Washington County where heavy snow is falling. An overall colder solution, similar to the Canadian model suite of the past few days, is unfolding. Adjusted the forecast to lower temperatures and slightly delay precipitation type changes per the latest observation. The rain/snow line is now only expected to make it into extreme southeastern Aroostook County, not to Houlton. Sub freezing temperatures remain all the way down into northern parts of coastal zones 29 and 30, much further south than modeled. Have issued an SPS for snow transitioning to rain and freezing on colder road surfaces across parts of Hancock and Washington Counties. Cannot rule out a few patchy icy spots over coastal zones but coverage should be lesser than inland areas.

Key Messages: 1) Winter Storm thru Tonight; Snow North, Rain South 2) Gusty Winds leads to Blowing Snow Thursday Night

Discussion...

1) Surface low pressure is lifting NE through New York State this evening with warm air advection over Maine. The boundary layer is very cold across much of the CWA except the Bangor region to Downeast coast where surface temperatures are 29-33F at this time. Light winds off the Gulf of Maine will continue to warm the boundary layer. Precipitation is underway in portions of the CWA as noted by webcams and KCBW radar data. Precipitation will continue to fill in over the next 1-3 hours with accumulations underway.

Tonight as the 500mb trof to our WNW pivots shortwave energy over the area expecting a period of moderate snow to develop. Bangor region to Downeast coast intially starting as a snow or rain/snow mix will quickly go to rain. Cannot rule out an hour of freezing rain especially north and west of I-95 in the Bangor Region to Lincoln/Howland regions. North of a line extending from Guilford to Millinocket to Houlton is expected to remain all snow. Latest consensus in the 925-700mb max wet bulb temperatures keep the 0C line south of Houlton and Guilford so confidence has increased on this placement. South of this line expecting a change over to rain. Intially 15:1 ratio snow will fall to 6-9:1 ratio near the transition line and 10-13:1 ratio snow north of that line in Northern Maine. Eventually changing back to a 15:1 or greater ratio snow by the end of precipitation overnight tonight. Precipitation will end between 1-2AM in SW zones and 2-4AM in NE zones. This will result in a widespread 5-8 inches across Northern Maine, 3-5 inches for Central Highlands and to the Houlton area with lesser amounts in the Bangor region to interior Downeast of 1-3 inches.

Given these snow totals, brief freezing rain opted to have a Winter Weather Advisories for Bangor Region, Central Highlands to S. Aroostook County. 1-3 inches for southern areas near I-95 in Bangor Region then 3-5 inches for areas N and W of I-95 and up in the Baxter to Houlton regions. Up to a tenth of an inch of ice is possible but most areas generally a light glaze. Across Northern Maine where the Winter Weather Advisory is in effect expecting 5-8 inches of snow.

2) Tomorrow afternoon expecting the intially surface low to track into the Maritimes with a secondary low over far SE Quebec near the western Maine mountains border. 500mb trof will be back across the Quebec/Ontario border with cold air aloft working towards our area. Latest modeling shows a TROWAL enhancing the development of light snow late in the day in Northern Maine. Have opted to bump up POPs to likely and above tomorrow night in these regions with light snow likely. The column will significantly cool and allow for higher ratio snow of 20:1 or greater. Hi-res cams have really displayed this TROWAL well in the last several runs and given the high ratio and slightly increased QPF expecting 1-2 inches of fluff. As the low tracks east expecting winds to rapidly increase from the west. Winds tomorrow afternoon and evening will begin gusting 20-30mph. Tomorrow night those winds will increase gusting 20-35mph across much of the CWA. Any locations in Northern Maine that gets light and fluffy snow will see areas of blowing and drifting snow. Expect potential impacts to all N-S oriented roads in Aroostook County and N. Penobscot County along with Route 6 in the few open areas between Shirley and Greenville. Wind chills will also fall below zero tomorrow night as well.

SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/

Key Messages: 1) Windy Friday 2) Areas of Blowing Snow Persisting Friday in Open Areas of Northern Maine

1) Windy Friday: Tight pressure gradient behind the departing strengthening low pressure system will lead to gusty west winds during the day Friday. Gusts will be approaching advisory level, with gusts topping out 30-40 mph most areas. Some snow showers could persist Friday in the north, with any additional accumulation being very minor. Cool with highs in the low to mid 20s. Don't anticipate the wind will be enough to lead to power outages. However, the threat for blowing snow exists. See below key message.

2) Areas of Blowing Snow Persisting Friday in Open Areas of Northern Maine: Looking for a pretty significant blowing/drifting snow event Thursday night into Friday especially in open areas of Northern Maine such as the agricultural areas of Aroostook and Northern Penobscot, and around Moosehead Lake. Winds will be from the west. The snow will be the most susceptible to blowing in these areas because of recent snowfall from tonight's storm and from the little secondary event Thursday night. We don't anticipate any widespread blizzard conditions, but areas of blowing snow could very briefly bring some open areas to near zero visibility on roads. Drifting could be pretty substantial as well by the time the wind eases later Friday evening. It would be worse if we were in late winter with the deeper snowpack, but this will be a pretty significant blowing/drifting event by early winter standards. Dry and quiet conditions late Friday night into Saturday.

LONG TERM /SUNDAY THROUGH WEDNESDAY/

Key Messages: 1) Potential Snow Sunday/Sunday Evening, Mainly Downeast

1) Potential Snow Sunday/Sunday Evening, Mainly Downeast: A digging/strengthening upper trough moves through late Sunday from west to east. Almost all models/ensembles have a decent surface low pressure developing/strengthening over the Southern Gulf of Maine or somewhere a bit further south. Question is whether or not this system can get its act together fast enough and track far enough north/northwest to give our area any snow. Most models bring only minor snow to Downeast if any, but a notable minority of solutions bring moderate snowfall to Downeast. Going with just a chance of snow Downeast for now, but it's something to watch. There could be some blowing snow and decent wind on the back side of the system Sunday night/Monday.

Below average temperatures Monday/Tuesday, then some moderation in temperatures likely toward mid-week.

AVIATION /21Z WEDNESDAY THROUGH MONDAY/

NEAR TERM: FVE/CAR/PQI/HUL: IFR this evening with LIFR vsby and SN. Expect -SN to end overnight becoming VCSH/-SHSN. Light S-SE winds tonight. Cigs becoming MVFR tomorrow with VCSH/-SHSN. Winds shift W mid day and increase to 10-15kt with gusts up to 25kt around sunset/21z. Tomorrow night -SN returns with IFR/LIFR likely. BLSN will become an issue reducing vsby. W winds 10-15kt gusting 25-35kt.

BGR/BHB...IFR/LIFR cigs/vsby with -SN at BGR and then -RASN at BHB becoming -RA at both sites. TEMPO added to BGR for potential of brief heavier snow and a period of FZRA. S-SE winds 5-10kt. Overnight expecting -RA to end and improving to BKN VFR by tomorrow morning. Winds shift W mid morning and increase rapidly 10-15kt with gusts up to 30kt by late day. Expecting BKN VFR tomorrow night and W winds 10-15kt with gusts up to 35kt possible.

SHORT TERM:

Friday...VFR/MVFR with a chance/chance of snow showers north. VFR Downeast. West winds 15 to 20 knots with gusts 25 to 35 knots.

Friday night...VFR/MVFR north. VFR Downeast. West winds 10 to 15 knots with gusts up to 25 knots in the evening, decreasing overnight.

Saturday through Saturday night...VFR. West winds 10-15 knots, becoming light Saturday night.

Sunday through Monday...Low confidence. Potential of MVFR/IFR, mainly Downeast. NW winds increasing to 10-20 kts with gusts to 30 kts possible.

MARINE

NEAR TERM: Very complicated Marine forecast and headlines. For tonight a Small Craft Advisory for the Intra-Coastal Waters until 1AM. S winds 15-25kt with a few gusts up to 35kt and seas 3-6ft. Then have upgraded the Gale Watch to a Gale Warning from 7PM Thursday to 4PM Friday. W winds 20-30kt and gusts up to 40kt with seas 3-6ft. Southerly Small Craft Advisory winds tonight will briefly fall below SCA criteria Thursday AM. Winds will shift westerly and increase to Gale Warning criteria. For the Coastal Waters southerly to southwest gales tonight gusting to 35kt will briefly fall below Gale Warning criteria Thursday AM. Winds will shift westerly and increase back to Gale Warning criteria. West winds 25 to 35 kt with gusts up to 45 kt and seas 8 to 13 ft expected.

SHORT TERM: Gale force westerly winds continuing Friday and Friday evening, then diminishing to below small craft for Saturday through midday Sunday. Then around a 60 percent chance of northwest gales Sunday night. Seas Friday start out around 10 ft but decrease to 3 ft or less Saturday afternoon through Sunday, and then increase to around 5 ft on Monday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Winter Weather Advisory until 3 AM EST Thursday for MEZ001>004. Winter Weather Advisory until 1 AM EST Thursday for MEZ005-006- 010-011-015-031-032. MARINE...Gale Warning until 10 PM EST Friday for ANZ050-051. Small Craft Advisory until 1 AM EST Thursday for ANZ052. Gale Warning from 7 PM Thursday to 4 PM EST Friday for ANZ052.