textproduct: Caribou

WHAT HAS CHANGED

- Increased snow and sleet totals/reduced ice totals across the North/and expanded areas with snow/sleet/freezing rain to include interior Downeast Maine Tuesday night-Wednesday

- Extended SCA on the coastal ocean waters through 6PM Wednesday

- Confidence increasing in significant mixed wintry precipitation in Northern Maine late Thursday through Friday. The system has trended a bit warmer.

KEY MESSAGES

1) Wintry mix expected to develop later Tuesday and Tuesday night for at least the northern half of the forecast area, with a threat for slick surfaces and travel difficulties into the Wednesday morning commute.

2) Significant wintry precipitation late Thursday through Friday night, especially north of Bangor. This could lead to significant travel impacts from the Thursday PM commute through both the AM and PM commutes Friday.

3) Yet again weather system is likely for Saturday night/Sunday/Sunday night. This system could bring more impactful freezing rain and sleet, with probably a change to rain before it ends sometime Sunday night.

DISCUSSION

KEY MESSAGE 1... Wintry mix expected to develop later Tuesday and Tuesday night for at least the northern half of the forecast area, with a threat for slick surfaces and travel difficulties into the Wednesday morning commute.

KEY MESSAGE 1 DESCRIPTION... A northern stream shortwave trough tracks along the Canadian Border from the Great Plains to the Saint Lawrence River Valley Tuesday and Tuesday night, then into the Canadian Maritime Provinces on Wednesday. At the surface, this will result in a storm system tracking across the midwest Tuesday, to Near New Hampshire/Vermont by Wednesday morning, then across the northern Gulf of Maine to near eastern Nova Scotia by Wednesday evening. This track is a little farther south than the 00z guidance and as a result, the forecast has trended a little colder. The precipitation should be in two waves - the first with a 700 mb shortwave running out ahead of the main system should produce mainly light snow across the North and light rain/snow elsewhere, with limited, if any accumulations. The main precipitation push is with the main storm system from Tuesday night into Wednesday morning.

Based on this, here are the expected precipitation types/amounts from north to south:

- Northern Aroostook: Mainly snow is expected, with some sleet mixed in from time to time. While freezing rain cannot be completely ruled out here, it no longer is likely. Looks like about 3-5" of snow and sleet. Snow develops Tuesday afternoon and should end by mid-Wednesday morning.

- A box from Northern Somerset on east to Southeast Aroostook and then on south to Northern Washington County then back west to the southern Central Highlands. This area will experience the full wintry mix, with 1-3" of snow, around 1/4-1/2" of sleet and from 0.1 to 0.3 inches of ice. The precipitation begins as a snow/rain mix Tuesday morning, should go over to all snow for a few hours late Tuesday, then quickly becomes a wintry mix Tuesday evening, that should come to an end by around midday Wednesday.

- The Bangor Region, northern Hancock, and Central Washington County: Should see a rain/snow develop Tuesday morning, possibly changing to all rain Tuesday afternoon. Enough cold air pushes in Tuesday night on northeast surface flow, that should see some freezing rain (and if the depth of the low level cold pool is sufficient, possibly some sleet) Tuesday evening, before the precipitation changes to all rain after midnight. Should see up to an inch of snow and sleet, with up to a few hundreths of an inch of ice. Based on this, have expanded the winter weather advisory south into this region.

- Across coastal Downeast Maine, a mix of rain and snow is possible at the start of precipitation Tuesday morning, changing to all rain and remaining so until tapering off Wednesday afternoon. Around 1/2 to 2/3 of an inch of rain is expected. Note if the storm track shifts even 25 miles to the south, this could bring the risk of freezing rain into at least northern portions of the region. This possibility will need to be monitored for.

There is still some uncertainty on exactly how fast the storm will exit to the east. Because of this, did not change the end times of any headlines for now. If confidence increases on the end time of wintry precipitation being into Wednesday morning, later shifts could extend the end time of the Advisories.

KEY MESSAGE 2... Significant wintry precipitation late Thursday through Friday night, especially north of Bangor. This could lead to significant travel impacts from the Thursday PM commute through both the AM and PM commutes Friday.

KEY MESSAGE 2 DESCRIPTION... A very active weather pattern is place, with another storm on track late Thursday to Friday night. There is still significant uncertainty, but this mainly involves in the onset timing and the exact location of various precipitation types. The exact precipitation types will be determined by the low pressure track and how far north/south it tracks as it moves east through the area. A further north track means less cold air damming and warmer precipitation types, while a further south low track means more cold air damming and cooler precipitation types.

What we do know is that there is likely to be fairly substantial precipitation, much of it in wintry form, with the potential for not just snow vs rain, but also freezing rain and sleet. In terms of precipitation totals for the whole storm, there looks to be somewhere in the neighborhood of an inch of precipitation (liquid equivalent) from about Millinocket north, and a bit less south of Millinocket. Definitely plenty of moisture to work with. There has definitely been a warming trend with the models, with the general consensus now being mostly snow/sleet in the extreme north (St John Valley), a mix of snow/sleet/freezing rain from Caribou to Millinocket/Greenville, freezing rain and/or rain around Bangor, and mostly rain on the coast. But to emphasize, this is just the general consensus, and there is still a lot of north/south variability in where these precipitation types set up, probably about 100 miles north/south uncertainty. Also it's important to note that there is a bit of general warming trend through the event as we head into Friday, with some places probably going to a warmer precipitation type (such as snow to sleet, sleet to freezing rain, freezing rain to rain). That said, it isn't a strong warm push, and we are unlikely to see temperatures get much if any above freezing in the far north even toward the end of the event. We also have mentioned the uncertainty in onset time. Expanding on this, it could start as early as around dawn Thursday, or it could start as late as about midnight Thursday night. Tend to favor an onset on the later side, but this is something we will need to watch/revise as the time nears.

KEY MESSAGE 3... Yet again weather system is likely for Saturday night/Sunday/Sunday night. This system could bring more impactful freezing rain and sleet, with probably a change to rain before it ends sometime Sunday night.

KEY MESSAGE 3 DESCRIPTION... Compared to the previous systems, this one for the latter part of the weekend looks to be on the warmer side, with a low pressure track generally being just north of us. That said, it still appears to be cold enough for some impactful freezing rain and/or sleet on the front side of the system Saturday night or Sunday morning, especially in the north. Most areas are likely to change to rain later Sunday before it ends. Precipitation doesn't appear to be quite as heavy with this system as the Friday system, more in the range of a half inch rather than around an inch. This also is likely to lead to this system being less impactful than the Friday one.

AVIATION /18Z MONDAY THROUGH SATURDAY/

VFR throughout to get started. There is a low chance that MVFR conditions could occur northern terminals with any showers late this afternoon/early this evening. But confidence in this is too low to reflect in the TAFs at this time. Otherwise, high confidence in VFR at all terminals through at least 10Z. Should see MVFR conditions develop at KBHB by around/just after sunrise, then become IFR there and at KBGR by mid-late morning. MVFR and/or IFR conditions could develop at KHUL by around midday, with most likely VFR conditions, with a low chance of MVFR at the remainder of northern terminals early Tuesday afternoon.

SW winds G20-25KT veer to the NW into this evening as they lose their gustiness. Winds become light and variable at southern terminals this evening and at northern terminals overnight. Winds remain light and variable or become NNE-NE at less than 10KT Tuesday morning.

Tuesday afternoon/night: IFR or lower likely. Mainly Snow KFVE/KCAR/KPQI. Snow to a wintry mix KHUL. A wintry mix to freezing rain to rain at KBGR Tuesday night and rain at KBHB. NE-ENE winds G15-20KT possible.

Wednesday...Becoming VFR by around midday. NE winds G15-20KT possible at southern terminals.

Thursday...VFR early, with cigs falling towards MVFR/IFR depending on storm onset timing. NE winds around 5 kts.

Thursday night - Fri night...Decreasing conditions to IFR/LIFR in mixed precip types, and staying IFR/LIFR into Fri night. Great uncertainty remains in precip type at each individual terminal. Better chance at snow and sleet at northern terminals, and rain/freezing rain at southern terminals, but this is subject to change. E/SE winds 10 to 15 kts, becoming variable Friday night.

Saturday...Generally VFR. NE wind 5-10 kts.

MARINE

High resolution models, supported by observations no longer suggest at least 2 hours of gusts to gale force this afternoon, so no need for a short fused gale warning on the coastal ocean waters. Instead it appears that SCA conditions should persist through at least Wednesday afternoon on the coastal ocean waters - even if the winds slacken below SCA levels, the seas should remain solidly above SCA thresholds due to a persistent swell. As a result, have extended the SCA on the coastal ocean waters through 6 PM Wednesday. Kept the SCA as is on the intra- coastal waters, expiring at 6AM on Tuesday. For now it appears that gusts and seas should stay just below SCA levels there Tuesday- Wednesday.

Conditions will trend upwards towards gales Tuesday night, then winds decrease once more Wednesday night behind a cold front. Seas 3 to 5 ft to increase towards 7 to 12 ft Tuesday night, then gradually improve through the second half of the week.

E/NE winds at or just below small craft Wed night to Thu night, then becoming S Fri and then switching to NE Sat and likely remaining small craft with winds through this period. Seas 3-7 ft Wed night to Sat.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Winter Weather Advisory from 6 PM Tuesday to 11 AM EDT Wednesday for MEZ001>006-010-011-015>017-031-032. MARINE...Small Craft Advisory until 6 PM EDT Wednesday for ANZ050-051. Small Craft Advisory until 6 AM EDT Tuesday for ANZ052.