textproduct: Caribou

WHAT HAS CHANGED

Updated onset timing of second wave of precipitation on our website. Update to 00z aviation discussion.

- Speed up timing of the cold front tonight.

- Decreased precip chances for Wednesday using high res models.

- Increased QPF for Thursday Night into Friday resulting in increased snowfall, sleet and freezing rain accumulations.

- Added sleet into the forecast Saturday night into Sunday AM with the snow and freezing rain.

KEY MESSAGES

1) Wintry mix continues through tonight, with a threat for slick surfaces and travel difficulties into the Wednesday morning commute.

2) Widespread wintry precipitation Thursday evening through Friday afternoon, which could greatly impact Thursday evening, Friday morning, and potentially Friday evening commutes.

3) Another system moves through region this weekend, bringing the potential for another round of snow/rain/freezing rain, that could impact travel.

DISCUSSION

KEY MESSAGE 1...Wintry mix continues through tonight, with a threat for slick surfaces and travel difficulties into the Wednesday morning commute.

KEY MESSAGE 1 DESCRIPTION... The exiting coastal low this evening will bring a dry slot across the region until after sunset tonight. By early tonight, the warm front of the low will move through the region with the cold front moving through fairly quickly behind.

Warm Front: Though the dry slot is expected to last into early tonight, the precip coming in behind it will move in quickly. The majority of the region will experience some sort of precip before midnight tonight. The high res models have been consistent with the precip types, with the majority of the freezing rain and sleet in the Central Highlands, rain to the south, and snow in the north.

Cold Front: High res models have drastically speed up the timing of the cold front passage and exit. In addition, upper air model sounding indicate ample dry air in the upper and mid levels moving into the region by the early morning hours of Wednesday. This decreased the chance of precip in the morning to scattered to isolated showers. However, this does mean a stronger change of freezing rain and sleet tonight, especially with the cooler nighttime temps and weak E winds.

Accumulations for ice, sleet, and snow have increased with the newest model updates. Though the precip should be out of the region by Wednesday morning, there is still concern for slick travel during the morning commute.

KEY MESSAGE 2...Widespread wintry precipitation Thursday evening through Friday afternoon, which could greatly impact Thursday evening, Friday morning, and potentially Friday evening commutes.

KEY MESSAGE 2 DESCRIPTION... A parent low pressure system will track into the Great Lakes and Ontario Thursday night. A mid-level warm front lifts over the region Thursday into Friday, bringing warmer temperatures into the region. With this system, precipitation begins to fill in from southwest to northeast. Surface high pressure north of the Gaspe Peninsula will allow for a cold air damming profile to set up over Maine. Cold air ahead of the warm front allows for mostly snow showers Thursday into Thursday night, before warm mid-layer warm air moves in, this will lead to the transitioning of snow over to sleet then freezing rain. Expecting 1-3 inches of snow for most areas from Moosehead to Baxter to Houlton and points northward with potentially up to 5 inches in the St. John Valley. Brief sleet may result in accumulations of 0.1 to 0.3 inch for the Central Highlands to Northern Maine. Lastly, highest chances of freezing rain are in interior Downeast, Central Highlands, and all of Aroostook county. Majority of this ice is expected to fall Thursday night into Friday mid morning, causing a potential for significant travel impacts for Friday morning commute. Roughly around 0.1 to 0.2 inches of ice accretion is possible. The boundary layer will warm on Friday turning all areas from south to north to rain.

Precipitation types are going to heavily depend on the track of the low pressure system. Northerly track will bring would bring period of freezing rain farther north in the state, while a southerly track would bring more snow to the north. Despite decreasing precipitation trending models currently, there is still a decent moisture column and PWATS around 0.75 to 1 inch with this system. Temperatures rise above freezing on Friday and all precipitation should transition over to rain during the day. Precipitation intensity starts to diminish overnight on Friday, but rain/snow showers persist through the upcoming weekend.

KEY MESSAGE 3...Another system moves through region this weekend, bringing the potential for another round of snow/rain/freezing rain, that could impact travel.

KEY MESSAGE 3 DESCRIPTION... Another low pressure system moves through the area Saturday night into Sunday. A chance for impactful snow, sleet and freezing rain in Northern and Central Highlands of Maine Saturday night, before switching over to all rain Sunday. ECMWF, Canadian and GFS are consistent in both anticipating a round of precipitation to occur in the north Saturday night into Sunday associated with overrunning, and another round of precipitation throughout the state Sunday into Sunday night ahead of the cold front. There remains significant timing uncertainties. Continue to monitor the forecast for updates, as the precipitation types of these storms will heavily depend on pressure system tracks.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

Tonight...MVFR/IFR cigs/vsby in snow, sleet, and freezing rain north terminals. Rain Downeast terminals. E winds around 5 kts.

Wednesday...IFR/MVFR cigs in the morning, then improving to VFR towards the evening. NNE winds 5-10 kts.

Wed night...VFR. Light and variable winds.

Thursday...VFR becoming MVFR late day. E-SE winds around 5kt.

Thursday night...IFR/LIFR. SN,PL,FZRA becoming RA at BHB and BGR by 12z Fri AM. SE winds 5-10kt. LLWS possible.

Friday...IFR/LIFR early with mixed precip changing to RA from S to N through the day. Becoming MVFR/IFR in the afternoon. S to SE winds 5-15kt. LLWS possible.

Saturday...VFR. MVFR cigs possible north. -SN/RA mix possible north. N winds 5-10kt shifting E-NE late day.

Saturday night...IFR/LIFR for SN/PL/FZRA north, RA south. SE winds 5-15kt.

Sunday...IFR/LIFR with mix precip north, RA south. Becoming MVFR/IFR with RA areawide. S-SE winds 5-15kt.

MARINE

Small craft advisory conditions continue tonight through Wednesday, with seas 3 to 7 ft. There may be a brief pause in advisory conditions this afternoon before swell returns tonight with a passing low pressure, and seas return to 5 to 9 ft. Wind gusts will begin to increase towards 25 kts late on Wednesday.

Winds and seas approach SCA criteria again by Friday, with these conditions lingering through the weekend. Chance for rain Wednesday, switching to a chance for snow Thursday into Friday morning. Chance of rain Friday through Sunday. NE winds Wednesday night, shifting to the SE Friday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Winter Weather Advisory until 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.