textproduct: Caribou

WHAT HAS CHANGED

* Updated aviation discussion through Friday coincident with 0z TAF issuance. Added PROB30 freezing drizzle to Caribou and Presque Isle TAFs this evening.

KEY MESSAGES

1) Flash freeze conditions tonight, freezing up any standing water on untreated surfaces. Could make commute hazardous.

2) Potential for some gusty winds and blowing snow in the north on Friday, reducing visibility.

3) Light snow Saturday afternoon into Saturday night may cause minor travel impacts.

4) There is a low but notable potential (20-30 percent chance) of significant (4 to 6 inches or more) snowfall mainly along the Downeast coast Sunday afternoon to Sunday night.

DISCUSSION

KEY MESSAGE 1...Flash freeze conditions tonight, freezing up any standing water on untreated surfaces. Could make commute hazardous.

KEY MESSAGE 1 DESCRIPTION...Low pressure system in Canada continues to stay to our north, as a shortwave trough moves through northern Maine tonight. The associated cold front that moves in along with this system has a strong temperature gradient, so once the front passes over locations in northern Maine, temperatures will drop quickly. Front is expected to pass the northwest this evening, and through the rest of the area late tonight. Overnight lows in the low teens in the west and northwest, mid- to-upper teens in the northeast and interior Downeast, and mid-20s along the coast. There could be a hindrance to quickly dropping temperatures, however, as clouds are anticipated to stick round all night throughout the region. Did lower temperatures down to account for the cold air advection behind the front, but did not drop values down significantly past the NBM due to the aforementioned clouds. With rain falling all day in majority of the forecast region, wet surfaces that have been left untreated could freeze over, resulting in some slippery road conditions. Keeping an eye out for possible freezing drizzle this evening in the north as well, as clouds/moisture layer is presently -9C or warmer, meaning there may only be supercooled water, and thus freezing drizzle.

Additionally, there is a chance for the northern portions of the state to get some additional snowfall overnight. There could be roughly 1 to 2 inches of snowfall in the northwest, and around half an inch to an inch and a half in the north and northeast. SLRs begin to quickly increase as cold air is brought back into the region, making the new snowfall relatively light and fluffy, which can cover over untreated icy spots. As winds shift northwesterly behind the front, there is also chance for some plumes off of the St. Lawrence to move over the Crown of Maine, adding some more snowfall accumulations in the early morning. That being said, however, a decent amount of dry mid-level air moves in late tonight, which could knock down snow accumulation total a bit.

KEY MESSAGE 2...Potential for some gusty winds and blowing snow in the north on Friday, reducing visibility.

KEY MESSAGE 2 DESCRIPTION...As this low pressure system moves east into New Brunswick, pressure gradient behind it is anticipated to bring some gusty winds to the region. Northeastern, Central Highland, and Bangor regions could see winds up to 25-30mph. Anticipating 20-25mph gusts elsewhere. With the recently fallen fluffier snow, on top of the wetter snow from the day before, there is a chance for some of this recent snowfall to blow around in these wind gusts, reducing visibility. Blowing snow can accumulate on the roads, and with flash freeze occurring the night beforehand, could cover up some untreated icy spots on the roads. Exercise caution when traveling. Pressure gradient, and winds, begin to relax Friday night.

KEY MESSAGE 3... Light snow Saturday afternoon into Saturday night may cause minor travel impacts.

KEY MESSAGE 3 DESCRIPTION... A mid/upper level jet max will cross the area Saturday, leading to weak surface low pressure development. Models still differ with the exact placement and intensity, but a general swath of light snow is expected to develop Saturday afternoon and pivot eastward Saturday evening. Accumulations of 1 to 2 inches are most likely, although forecast soundings show favorable lift within the dendritic growth zone that may favor locally higher snow ratios and snow rates, particularly if the low is strong enough to locally enhance QPF from mid level frontogenesis. NBM probabilities show a broad swath of 10 to 25 percent chance of exceeding 4 inches of snow from just north of Bangor to around Caribou, indicating some potential for localized advisory level snowfall. Closer to the coast, mixing with rain is possible depending on the low track. The main impact from this system will be slick travel conditions Saturday afternoon and evening.

KEY MESSAGE 4... There is a low but notable potential (20-30 percent chance) of significant (4 to 6 inches or more) snowfall mainly along the Downeast coast Sunday afternoon to Sunday night.

KEY MESSAGE 4 DESCRIPTION... A shortwave trough will round the base of the longwave trough along the Gulf Coast Sunday morning, quickly pivoting up the mid-Atlantic coast by Sunday afternoon and leading to rapid surface low development over the Atlantic. Most models keep this system far enough offshore to have little to no precipitation for the area. However, a notable minority such as the 12z CMC, AI GFS, AI ECMWF, and 12z RRFS all show the low developing further west which could lead to more widespread snowfall and even potential for warning level (6 inch) snowfall along portions of the Downeast coast. The latest NBM probabilities of 4 inches or more are relatively low, with a broad swath of around 10 to 20 percent along and southeast of interstate 95. However, these do not include the more aggressive AI models, which is why the key message indicates up to a 30 percent chance instead.

AVIATION /00Z FRIDAY THROUGH TUESDAY/

KFVE/KCAR/KPQI/KHUL Tonight through Friday Night: As of 0z, cold front is progressing south and is around KPQI. Generally IFR both ahead of and behind the front (exception is KHUL which is presently MVFR). Main concern is for temperatures falling below freezing presenting the opportunity for freezing drizzle. Added in a PROB30 for fzdz for KCAR/KPQI 1-5z, which is where think it has the best chance of occurring. Far from a certainty though. Can't rule it out at FVE and HUL too, but didn't have enough confidence to put in the PROB30. Intermittent light snow develops later tonight and continues off and on through Friday morning. This light snow and possibly blowing snow will come with mainly MVFR conditions. Expect an improvement to VFR around 16-19z Friday. Winds increase to around 15 kts from the NW, with gusts to 25 kts, around 12-14z Friday, and continue to late afternoon, then slacken Friday night. VFR Friday night. KBGR/KBHB Tonight through Friday Night: Generally VFR tonight. However, BHB presently has 400ft ceilings, but think these dissipate by 2z to VFR. From roughly 8-13z Friday, MVFR ceilings appear likely, then VFR again after 13z Friday. Winds increase to W/NW 10-15 kts with gusts around 25 kts for the day Friday, then slacken Friday night. VFR Friday night.

Saturday to Saturday night: VFR/MVFR at northern terminals with -SN possible (50 percent chance). VFR/MVFR at Downeast terminals, with a period of IFR possible in -SN/SN (60 to 70 percent chance). Winds S at 5 to 10 kts.

Sunday to Sunday night: VFR/MVFR most likely with a low (20-30 percent) chance of IFR and steadier -SN/SN. SW winds 5 to 10 kts, shifting N/NW.

Monday to Monday night: MVFR/VFR with a chance of -SHSN. W winds 5 to 10 kts with gusts to 20 kts. Higher gusts possible later Monday night.

Tuesday: MVFR/VFR north, VFR south. W winds 10 to 15 kts with gusts to 30 kts.

MARINE

Small Craft Advisory out for the inter-coastal waters tonight into Friday evening. Gale Warning out for the outer waters, from early Friday morning, to early evening Friday. Seas will be the highest during the day on Friday, around 8-11 ft over the outer waters, and 5-7 ft over intra-coastals. Winds gradually fall below SCA criteria Friday night. Light freezing spray over all waters Friday. Some patchy fog remains over the waters this evening in spots, until this evening. Winds from SW tonight, shifting west by Friday.

Advisory level seas Saturday over the outer waters will decrease Saturday night to around 5 feet and remain fairly steady through Sunday night. Winds increase to advisory levels or marginal gales Monday, with a period of gales likely Monday night into Tuesday. Freezing spray risk returns on Tuesday onward as colder air overspreads the waters.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Gale Warning from 5 AM to 5 PM EST Friday for ANZ050-051. Small Craft Advisory until 7 PM EST Friday for ANZ052.