textproduct: Caribou

SYNOPSIS

A warm front will approach later tonight, then lift toward the Downeast region Thursday. An occluded front crosses the region Thursday night into Friday. Low pressure will approach Saturday, then cross the region Sunday. Another low will approach Monday.

NEAR TERM /THROUGH TODAY/

12:30 AM Update....Precipitation beginning in southwestern Maine. Reflectivity shows precipitation in our forecast region, but dewpoints are so low, so everything falling has been virga. Pushed the precip start time back another hour or two to match the current trends, until moisture starts to rise. Updated precip types with minor edits to match current model runs and temperature observations. Otherwise, previous forecast on track.

Previous discussion... No changes to the Winter Weather Advisories. High pressure will exit across the Maritimes tonight. At the same time, low pressure lifting toward the northern Great Lakes will draw a warm front toward New England. The low will track northeast across Quebec province Thursday, drawing the warm front toward the Downeast region. Retreating high pressure will help establish low level cold air damming across the region. At the same time, temperatures will steadily warm aloft. With increasing isentropic lift, overunning precipitation will expand northeast across the region overnight. Based on critical thicknesses, expect precipitation overnight mostly in the form of snow. However, the snow could begin to transition to a wintry mix across southwest portions of the forecast area late. The low level cold air will gradually be eroded, from southwest to northeast, across the region Thursday with warming temperatures aloft. This will allow snow to transition to a wintry mix and eventually rain, from southwest to northeast, across the forecast area Thursday. The wintry mix will hold on longest across northeast portions of the forecast area. Generally expect total snow and sleet accumulations through Thursday to range from 2 to 4 inches, with up to around a tenth of an inch of ice. Locally greater snow, sleet and ice accumulations are possible across central portions of the region along with the western highlands. Low temperatures tonight will occur during the early morning hours then begin to slowly warm overnight. Low temperatures will range from around 20 to the lower 20s north, to the mid to upper 20s Downeast. High temperatures will occur late Thursday. High temperatures will range from the mid 30s to around 40 north, to the lower 40s Downeast.

SHORT TERM /TONIGHT THROUGH SATURDAY/

A weakening low over Quebec will transfer its energy over to the Canadian Maritimes during Thursday night. This will result in a few more showers north of Katahdin during the night. Given warm thermal profiles, most of these showers will be in the form of rain. Though it will be dry near Bangor and Downeast, there will be enough low-level moisture around for some patchy fog there. Low temperatures Thursday night will be in the mid to upper 30s from the Central Highlands northward. The Bangor region and Downeast will see lows in the lower 40s.

High pressure will move eastward from the Midwest on Friday, while low pressure strengthens near Labrador. This will result in significant cold air advection on Friday aloft. The cold air advection will be accompanied by breezy northwesterly winds across the area. Thus, went a bit above NBM guidance for winds on Friday. Also cannot rule out an isolated rain or snow shower during the day Friday in the Crown of Maine. High temperatures will only rise a few degrees on Friday from the Central Highlands northward. Downsloping winds will allow a bit more warming for Bangor and Downeast, with upper 40s for highs.

High pressure builds in closer to the area Friday night. However, winds will take some time to diminish during the night. Hence, full decoupling is not expected Friday night. That said, decided to undercut NBM guidance for low temperatures somewhat. Most places will see lows in the 20s.

A low pressure system will track into Quebec on Saturday, dragging a warm front towards Maine. Warm air advection precipitation will begin in southwestern portions of the area mid to late afternoon. Initially, there may be enough boundary layer warmth for p-type to start as light rain or a rain/snow mix. Nevertheless, thermal profiles are cold enough that p-type will become snow once steadier precipitation arrives. Northeastern areas will likely remain dry until sunset or perhaps just after.

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/

Snow with the aforementioned low pressure system will overspread the entire region Saturday evening. Enough warm air will work in to Bangor and Downeast during Saturday evening to cause snow to mix with then change to rain. Snow will change to a wintry mix from the Central Highlands northward late Saturday night. Soundings indicate a period of sleet, then freezing rain is likely. A couple of inches of snow and sleet could accumulate, along with light icing, for central and northern areas. Snow accumulations in the Bangor region and Downeast are expected to be minimal at this time.

Steady precipitation is forecast to exit northern areas Sunday morning. With the lightening of precipitation and daytime warming, any leftover precipitation will change to plain rain. Colder air works back into the area from northwest to southeast Sunday night. Some models and ensembles show a second wave of low pressure tracking through the Gulf of Maine during that time. This could bring light snow to the Central Highlands and North, and a light rain/snow mix for Bangor and Downeast.

Forecast confidence is low for late Tuesday into Wednesday of next week. The 12z GFS and CMC models show a strengthening low pressure system in the Gulf of Maine, tracking towards the Bay of Fundy. These solutions would bring a substantial snowstorm to much of Northern and Eastern Maine. The 12z ECMWF has the system, but much weaker and further south. This would only bring some light snowfall to the Bangor and Downeast regions Tuesday night. Ensemble members show a significant spread regarding accumulations at this time. Will continue to monitor and update this part of the forecast as it gets closer.

AVIATION /06Z THURSDAY THROUGH MONDAY/

NEAR TERM:

KFVE/KCAR/KPQI/KHUL: VFR for the next few hours before precipitation begins. MVFR/IFR conditions then develop later this morning with developing snow. IFR/LIFR Thursday with snow transitioning to a wintry mix, with freezing rain and sleet possible at all terminals. Transitions over to rain by late afternoon. Low level wind shear at all terminals late Wednesday evening into Thursday morning. Light SE winds at 5-10 knots, with gusts up to 30 kts this morning in northern terminals. South/southwest winds later today at 10-15 knots.

KBGR/KBHB:VFR for the next few hours before precipitation begins. MVFR/IFR conditions then develop later this morning with developing snow. IFR/LIFR Thursday with snow transitioning to a wintry mix, with freezing rain and sleet possible at all terminals. Transitions over to rain by late afternoon. Low level wind shear at all terminals late Wednesday evening into Thursday morning. Light SW winds at 5-10 knots, with gusts up to 30 kts this morning. South/southwest winds later today at 10-15 knots.

SHORT TERM: Thursday night...IFR/LIFR conditions early with -SHRA North and BCFG Downeast. Improving to MVFR/VFR late. Rain tapering to showers by nighttime. Patchy fog at southern terminals possible. Winds S at 5-10 kts, becoming W by daybreak.

Friday...Mainly VFR. Brief MVFR possible at Aroostook terminals with VCSH and low stratus. Winds NW 10-15 kts, gusting 20-25 kts.

Friday Night...VFR. Winds NW 10-15 kts early, light N winds late.

Saturday...VFR in the AM. Trending to MVFR in the PM with -SHSNRA. IFR possible late at BGR. Light N winds AM. Winds SE 5-10 kts PM.

Saturday Night...Mainly IFR or lower. -SN early, changing to -RA at BGR and Downeast, and a mix North. Winds SE 5-10 kts, gusting 15-20 kts.

Sunday...Mainly MVFR/IFR with -SHRA. Some -SHSN possible at Aroostook Terminals in the AM. SE wind 5-10kts becoming SW late.

Sunday Night-Monday...Mainly MVFR. IFR possible Sunday night with -SN or -RA. Winds NW 5-10 kts.

MARINE

NEAR TERM: A Small Craft Advisory is in effect for all the waters late tonight through Thursday. A few wind gusts could approach gale levels Thursday. Snow developing tonight. An early wintry mix changing to rain Thursday.

SHORT TERM: Winds and seas will be above Small Craft Advisory criteria through Thursday night. Conditions subside below SCA levels Friday morning on the intra-coastal waters. Winds and seas remain at borderline SCA criteria through the day Friday on the outer waters, before subsiding Friday evening. Conditions will be sub-SCA for Friday night and through Saturday. Winds and seas build back above SCA criteria Saturday night into Sunday. Winds diminish below SCA levels Sunday night, but seas remain close to SCA levels through Monday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Winter Weather Advisory until 5 PM EDT this afternoon for MEZ001-002-005-006. Winter Weather Advisory until 2 PM EDT this afternoon for MEZ003-004-010-011-031-032. Winter Weather Advisory until noon EDT today for MEZ015>017- 029-030. MARINE...Small Craft Advisory from 5 AM early this morning to 8 AM EDT Friday for ANZ050>052.