textproduct: Caribou

SYNOPSIS

Low pressure moves into the northern Canadian Maritimes through tonight. High pressure builds in Saturday and Saturday night, then exits to the east on Sunday,as low pressure approaches from the west. A warm front crosses Sunday evening, followed by a cold front crossing Maine late Sunday night and Monday morning. High pressure then moves in from the west through Monday night. A coastal low approaches from the south on Tuesday.

NEAR TERM /THROUGH SATURDAY/

6am Update...Made minor changes with this update to reflect the latest trends in observations and guidance. The forecast appears on track.

Previous Discussion... As a cutoff low passes to the north, a shortwave trough rotates around its base across Maine today. This will bring isolated to scattered snow showers (rain or snow showers for coastal Downeast). Steep low to mid level lapse rates around 8-9C/km up to around 750mb this afternoon will allow for for locally strong snow showers producing reduced visibilities and the potential for a quick accumulation of snow. Will continue to highlight this threat in the HWO and on social media. Highs today should range from around 30 to around 40, which is near normal.

The cutoff low exits to the northeast tonight. Cannot rule some lingering isolated to scattered snow showers early across the North. Should see diminish clouds through the night. Lows tonight should generally be from the lower 20s to upper 20s, which is around 5 degrees above normal.

A northern stream shortwave moves across Saturday morning, followed by northern stream ridging building over the area Saturday afternoon. Other than possibly some isolated to scattered snow showers over far NW zones with the shortwave in the morning, it should be dry, with decreasing cloudiness through the day. Highs on Saturday should be around 5 degrees below normal.

SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/

Key Message...Light snow event for Northern Maine Sunday and Sunday evening likely to impact travel.

Chilly Saturday night with high pressure overhead, with lows mainly in the teens. The high pressure quickly moves east Sunday as the next system races in. This system will feature a primary surface low pressure passing from southwest to northeast to our north. An occluded front will be draped south of the surface low, with perhaps a weak triple point surface low developing over central portions of our area as it moves through.

Importantly, precipitation looks to develop midday/early afternoon Sunday, and will start as snow to the north of Bangor, perhaps mixed with snow at the onset around Bangor but quickly changing to rain. Precipitation doesn't look terribly heavy, but the snow should be heavy enough to lead to hazardous travel conditions along and north of a roughly Dover-Foxcroft/Lincoln/Danforth line during the afternoon. There's a pretty good mild southerly wind at low-levels with this system, and think that most areas along I-95 and up into Eastern Aroostook will warm freely and mix with or change to rain from south to north late afternoon into the evening before tapering off around midnight. There is a bit of model uncertainty as to how quickly/how much the warm air surges north, and if a stronger triple point low develops over central portions of the area, that could shut off the warm advection and keep the north all snow. That said, the more likely solution is a changeover to rain for all but areas from Fort Kent west/southwest into the North Woods. For snow totals, this is not looking like a terribly significant event, with generally 1-4 inches of fairly wet snow north of the Dover- Foxcroft/Lincoln/Topsfield line, with highest amounts in the North Woods and St John Valley. Can't rule out a few spots higher than 4 inches, but think the upper ceiling for this event is about 6 inches, and if this occurs, it would most likely be in the St John Valley or North Woods.

South/southeast winds will be decent for this event with 10-15 mph with gusts to 25 mph where the snow will be falling. With the snow being fairly wet, didn't add any blowing/drifting snow to the forecast, but there may be some small amounts of blowing/drifting snow occurring Sunday afternoon/evening. Winds look a bit stronger toward the coast. Can't rule out needing a wind advisory for the coast Sunday afternoon/evening, with gusts topping out somewhere in the 35-45 mph range. Don't anticipate anything more than isolated power outages.

Models overall are in good agreement for the Sunday/Sunday evening storm.

LONG TERM /MONDAY THROUGH THURSDAY/

Key Message...Possible significant snow Tuesday/Tuesday night, best chance Downeast.

Colder air rushes back in from the west behind the system Monday with gusty westerly winds, with temperatures likely steady or slowly falling through the day. There should be a big enough gap in the precipitation ending Sunday night and the sub-freezing temperatures that don't expect a flash freeze on the vast majority roads, though icy spots in driveways are likely Monday afternoon/evening.

Very cold Monday night as high pressure builds in, with lows 10-15 above Downeast and 5 below to 10 above in the north, coolest in the valleys.

Then attention turns to a potential major winter storm Tuesday/Tuesday night, coming from a fast-moving upper trough and surface low passing from west to east to our south. It's very important to note this is just a possibility, and far from a certainty. A slight majority of models/ensembles bring significant snow to at least central/southern portions of the area, but a significant minority bring nothing and keep everything south of our area. A few probabilities of note from the NBM...45-70 percent probability of at least 1 inch, 35-50 percent probability of at least 4 inches, and 25-40 percent probability of at least 8 inches. Bottom line is this system has what you could call a high ceiling/high potential, but it is only a possibility at this point.

Beyond the potential Tuesday/Tuesday night storm, we'll be looking at a potential Arctic front late Thursday or Thursday night. Lots of uncertainty this far out, but potential does exist for extremely cold air toward Friday and snow showers or squalls if we do get the Arctic front.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

NEAR TERM: With the possible exception of a chance for MVFR or lower conditions in very localized heavy snow showers in the late afternoon/early evening at KFVE/KCAR/KPQI/KHUL (best chance at KHUL) - it should be VFR through the TAF period. Winds become SW at under 10KT by around midday. Should see some gusts to 15-20KT at southern terminals this afternoon. Winds become W at around 10KT overnight.

Saturday...VFR. W-WNW winds G15-25KT possible.

SHORT TERM: Saturday Night. VFR. Variable wind less than 10 kts.

Sunday and Sunday night...VFR early Sunday, becoming IFR/MVFR in the afternoon and into Sunday night. Snow and rain, with rain more favored for BGR/BHB. S winds 10-20 kts with gusts 20-30 kts, strongest winds BHB/BGR. LLWS likely.

Mon...VFR, except possible MVFR north. NW wind gusting 20-30 kts.

Tue...MVFR or lower possible in snow, especially south, but confidence is low.

MARINE

NEAR TERM: SCA conditions become Gales by this afternoon on the coastal ocean waters and should last through Saturday. As a result have moved up the start time of the Gale to noon today and extended its end time to 6pm Saturday. For the intra-coastal waters, it appears that SCA conditions should start by mid morning and last through Saturday, so have adjusted the SCA timing to 8am today through 6 pm Saturday.

SHORT TERM: South gales expected (greater than 75 percent chance) late Sunday and Sunday night, with seas to around 10 ft. Winds switch to the west Monday but remain near the border of small craft and gale. Much improved winds/seas Monday night/early Tuesday, but about a 50 percent chance of gales around Tuesday night from a possible Nor'easter. Seas could also build back up to around 10 ft, depending on the track of the Nor'easter.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Gale Warning from noon today to 6 PM EST Saturday for ANZ050- 051. Small Craft Advisory until 6 PM EST Saturday for ANZ052.