textproduct: Caribou

WHAT HAS CHANGED

-QPF increased for the Wednesday through Thursday winter storm.

-Temperatures decreased on Wednesday, allowing the mixed precip to reach the coast.

-Confidence has increased in the extent of the mixed precip.

KEY MESSAGES

1) Heavy mixed precipitation is likely across northern Maine Wednesday into early Thursday. Significant accumulations of snow, sleet, and freezing rain are possible and could result in travel impacts and isolated power outages.

2) Two additional storm systems are likely to bring snow or wintry precipitation to all or most of the forecast area, the first Friday night into Saturday, then the second Sunday afternoon into Monday. Both of these systems have the potential to disrupt travel. The second system has potential for additional impacts from strong south winds depending on its track.

3) Temperatures will remain unseasonably warm through Tuesday resulting in snow melting, and ice rotting on rivers and lakes.

DISCUSSION

KEY MESSAGE 1...Heavy mixed precipitation is likely across northern Maine Wednesday into early Thursday. Significant accumulations of snow, sleet, and freezing rain are possible and could result in travel impacts and isolated power outages.

KEY MESSAGE 1 DESCRIPTION... Ensemble and deterministic models are coming more into agreement on the track of the storms for Wednesday into Thursday. The question still remains on how cold the surface temps will get in order to hold on to the respective precip types throughout the day. Below are the details on what to expect:

Snow: Precip is expected to begin Tuesday night with the warm front moving into the region. Temps are expected to drop below freezing in the north throughout the night, which will produce mainly snow. Due to the increasing QPF and a cooler solution, snow is expected to be impactful. The high impacts are mainly due to snow amounts and the heavy, wet snow consistency.

Freezing Rain and Sleet: The warm front is expected to overrun the cooler surface airmass, causing mixed precip to develop. The question will be the extent of the warm airmass in the mid levels. As of this update, the Central Highlands and higher terrain should see freezing rain and sleet first in the early morning hours of Wednesday. By sunrise on Wednesday, the freezing rain and sleet should expand north and south, reaching into the Bangor Region and central Aroostook. By the afternoon, freezing rain and sleet mixed with snow in the far north and rain in the south will spread across the region. By Wednesday night, the S flow should increase, eroding the CAD and switching the majority of the precip to rain. Due to the long period of mixed precip, ice and sleet amounts will be higher, creating dangerous road conditions.

Rain: Though coastal Downeast is expected to see brief periods of mixed precip, the area should be mostly rain. Due to the warmer temps and and higher PWATs, rain amounts are expected to be high for the area in the beginning of March. The frozen ground will cause the majority of the rain to run off into rivers and small streams. This coupled with the rotting ice and snow could cause ice to move on the rivers.

Wind: The tightening pressure gradients with this system will create gusty winds throughout Wednesday into Thursday. Gusty wind, ice covered surfaces, and heavy wet snow could cause isolated power outages.

KEY MESSAGE 2...Two additional storm systems are likely to bring snow or wintry precipitation to all or most of the forecast area, the first Friday night into Saturday, then the second Sunday afternoon into Monday. Both of these systems have the potential to disrupt travel. The second system has potential for additional impacts from strong south winds depending on its track.

KEY MESSAGE 2 DESCRIPTION... Per the previous discussion: An active pattern will set up this weekend into early next week with two additional systems likely to impact travel. The first on Friday night into Saturday is currently favored (roughly 60 percent of members) to track along the coast as a vigorous shortwave trough exits the Great Lakes. This scenario would result in a moderate snowfall across nearly the entire area, with the heaviest amounts across central and Downeast areas. A large minority of guidance tracks the low farther to the northwest, which would result in a large dry slot moving over the area, leading to less precipitation. This solution would also be warmer with some potential for mixing closer to the coast.

A second system is also likely Sunday night into Monday as a longwave trough pivots across the Great Lakes, leading to another surface low moving northeast from the Great Lakes. This system is very likely to be stronger than the early weekend system, but its track varies significantly which will determine impacts. If a stronger low tracks west of the area, which is currently the slightly favored solution, a strong south wind could lead to issues, especially along the coast. Precipitation will likely start frozen regardless of the track, especially away from the coast, so at least some travel impact is looking likely from this system.

KEY MESSAGE 3...Temperatures will remain unseasonably warm through Tuesday resulting in snow melting, and ice rotting on rivers and lakes.

KEY MESSAGE 3 DESCRIPTION... Warm and increasingly humid air continues to funnel into the area tonight and tomorrow. Low temperatures tonight will remain above freezing in most areas, though will drop to below 30 over the North Woods. This will stop the snowmelt overnight acrs the northwest with snowmelt slowing over the remainder of the area tonight.

Given the thawing degree hours through Tuesday, ice is likely to rot over northern rivers with some movement possible over southern rivers. High temps for Tuesday likely to warm into the 60s over interior Downeast and the Bangor Region, though onshore flow may keep the coast in the 50s. Colder air associated with 1030mb high building south out of Canada may keep northern Aroostook down in the 40s for highs on Tuesday.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Tonight...BHB may experience MVFR vsbys in BCFG between 08-13z but remainder of terminals expecting VFR conditions tonight. SW winds overnight with LLWS this evening into the overnight hours at all sites.

Tuesday...VFR. NW 5-10kts north, becoming N all terminals in the afternoon.

Tuesday night...VFR early becoming MVFR at southern terminals late. MVFR/IFR possible at northern sites late in light snow or mixed precipitation. NNE 5-15kts.

Wednesday to Wednesday Night...Deteriorating to MVFR/IFR with rain south and mixed precipitation north. E winds 5 to 10 kts with gusts to 20 kts.

Thursday to Thursday Night...Improving to VFR. W winds around 10 kts with gusts to 25 kts.

Friday...VFR. W winds 5 to 10 kts with gusts to 20 kts possible.

Saturday...IFR/LIFR in snow. N winds 5-15 kts.

MARINE

Seas gradually increase above small craft levels this evening over outer waters. Winds gust above 25kts at times tonight over all waters. Conditions remain below small craft conditions through Tuesday night.

Winds and seas will increase to Small Craft Advisory thresholds on Wednesday before winds likely increase to Gale force Wednesday night through Thursday evening over the outer waters, and possibly over the intracoastal waters as well. Another period of gales is possible Friday night into Saturday and again Sunday night to Monday.

CLIMATE

A preliminary record high of 50 degrees was set in Caribou today. Daily high temperatures approaching records are possible again tomorrow.

Tuesday, March 10

Caribou: Forecast 44 F; Record 55 F set in 1977 Houlton: Forecast 53 F; Record 58 F set in 1977 Millinocket: Forecast 58 F; Record 54 F set in 2016 Bangor: Forecast 61 F; Record 62 F set in 1977

CAR WATCHES/WARNINGS/ADVISORIES

ME...Winter Storm Watch from Wednesday morning through Thursday morning for MEZ001>006. MARINE...Small Craft Advisory until 8 AM EDT Tuesday for ANZ050>052.