textproduct: Caribou

WHAT HAS CHANGED

- Chances for major impacts from a noreaster Sunday afternoon into Monday have decreased slightly, but the threat remains, mainly for coastal and Downeast Maine. - Updated aviation discussion.

KEY MESSAGES

1) 1 to 3 inches of snow is likely over northern Maine later today through tonight.

2) Dangerous wind chill temperatures tonight into Friday morning for northern Somerset and northern/central Piscataquis counties.

3) There is still potential for impacts from a storm Sunday afternoon into Monday. Coastal areas have the greatest chance of significant impacts from strong wind gusts and snowfall.

DISCUSSION

KEY MESSAGE 1... 1 to 3 inches of snow is likely over northern Maine later today through tonight.

KEY MESSAGE 1 DESCRIPTION... Persistent low pressure in the vicinity of Labrador will wrap modified maritime air back toward the forecast area from the northeast today through tonight. Models indicate isentropic lift with warm advection moving toward northern Maine from the Maritimes today through tonight. This lift will support an area of light overrunning snow which will begin to reach northern portions of the forecast area this afternoon then persist overnight into Friday morning. Storm total snow accumulations across northern portions of the forecast area through Friday morning will range from 1 to 3 inches. The light snow will generally impact areas north of a line from Greenville, to Millinocket, to Danforth. The greater accumulations will occur across northern portions of Aroostook county. The snow will taper to snow showers Friday afternoon.

KEY MESSAGE 2... Dangerous wind chill temperatures tonight into Friday morning for northern Somerset and northern/central Piscataquis counties.

KEY MESSAGE 2 DESCRIPTION... The combination of wind and cold temperatures will produce dangerous wind chill temperatures across portions of northern Somerset and northern/central Piscataquis counties later tonight into Friday morning. A Cold Weather Advisory remains in effect for these areas for apparent temperatures of around 20 to around 25 below zero.

KEY MESSAGE 3... There is still potential for impacts from a storm Sunday afternoon into Monday. Coastal areas have the greatest chance of significant impacts from strong wind gusts and snowfall.

KEY MESSAGE 3 DESCRIPTION... A strong upper level low over the Southeast will reach the coast Saturday evening, causing rapid cyclogenesis to occur just offshore as the low moves northeast, with surface pressures forecast to fall below 970mb on most guidance by 0z Monday. While enough uncertainty remains for major differences between impacts, the general trend has been for a further offshore low with lesser impacts. However, there remains a slight (about 20 percent) chance of warning level snowfall and strong winds, possibly close to blizzard conditions along the coast. The ECMWF and its ensemble continue to be the most aggressive with deterministic and ensemble QPF suggesting over a half inch of QPF for the coast and wind gusts in excess of 45mph, while its ECMWF AI is much less aggressive. Interestingly, the GFS AI model is also less aggressive with QPF along the coast compared to its deterministic run, showing nearly nothing. AI model guidance has generally made positive improvements on the deterministic solutions so far this winter, so this does slightly tilt the forecast confidence towards a miss for most of the area. While astronomical tides will be high, offshore winds should mitigate any coastal flooding threat assuming the current general surface low pressure track holds. This remains a low probability event with potentially major impacts, especially for coastal areas, so it is important to continue to monitor the latest forecasts.

AVIATION /12Z THURSDAY THROUGH MONDAY/

Across northern areas, expect VFR conditions this morning through early afternoon. MVFR/IFR conditions then begin to develop this afternoon with developing light snow. MVFR/IFR, occasional LIFR, conditions then occur tonight into Friday morning with light snow. VFR/MVFR conditions Friday afternoon with snow showers. Across Downeast areas, generally expect VFR conditions today through Friday. West/northwest winds 10 to 15 knots with gusts up to 20 to 25 knots today through Friday.

Friday night to Sunday AM: VFR. WNW winds 5 to 10 kts.

Sunday PM to Monday AM: VFR at northern Aroostook County terminals, with increasing chances for MVFR in -SN closer to the coast at KBGR and KBHB depending on the track of an offshore storm. Small (10 to 20 percent) chance of major impacts with IFR/LIFR or lower in heavier snow and blowing snow at BHB. North winds around 10 kt gusting to 20 kt at northern terminals and 20 kt gusting to 30 kt at southern terminals. Winds may be stronger in some scenarios, especially closer to the coast.

Monday PM/Night: VFR. NW winds 10 to 20 kts with gusts to 30 kts possible.

MARINE

A Small Craft Advisory remains in effect for all the waters this afternoon into Friday. Light freezing spray today. A Freezing Spray Advisory, for moderate freezing spray, remains in effect from this evening into Friday afternoon.

Wind gusts to around 25 kt are possible over the outer coastal waters Friday evening before gusts and seas fall well below Small Craft Advisory thresholds. Light to moderate freezing spray is forecast Friday night into Saturday morning. Seas diminish to 2 feet or less Saturday into Saturday evening, before increasing again Saturday night into Sunday. Gale force winds are expected (90 percent chance) with Storm Force winds possible (30 to 40 percent chance) Sunday into Monday. Visibility reductions are possible in snow, especially further offshore. Light to moderate freezing spray returns Saturday night through Monday morning.

CAR WATCHES/WARNINGS/ADVISORIES

ME...Cold Weather Advisory from midnight tonight to 10 AM EST Friday for MEZ003-004-010. MARINE...Small Craft Advisory from 1 PM this afternoon to 1 PM EST Friday for ANZ050-051. Freezing Spray Advisory from 7 PM this evening to 1 PM EST Friday for ANZ050>052. Small Craft Advisory from 4 PM this afternoon to 7 AM EST Friday for ANZ052.