textproduct: Caribou

WHAT HAS CHANGED

Increasing confidence in storm during the middle of next week.

KEY MESSAGES

1) Wintry mix Friday night into Saturday morning could create slippery travel. Visibilities may be limited by areas of fog.

2) Above normal temperatures dominate through next week, and could lead to snow melt and river/lake ice rot.

3) Potential for a storm Wednesday into Thursday, that could bring rain/snow and chances for wintry mix.

DISCUSSION

KEY MESSAGE 1...Wintry mix Friday night into Saturday morning could create slippery travel. Visibilities may be limited by areas of fog.

KEY MESSAGE 1 DESCRIPTION... Ridge axis will trap cold air over central areas on Friday, remaining through Friday night leading to cold air being dammed up against the higher terrain. Warm front will lift through the area Friday night with a warm nose around 800mb.

Forecast sounding continue to show cold air damming in favored areas butting up again the terrain, especially in the Central Highlands and up through Houlton, though the Bangor area through the Downeast region could see a brief period of freezing rain and/or sleet before temperatures quickly rise above freezing.. Have slowed pops slightly as guidance has a bias of saturating dry air aloft more quickly than ends up happening. That said, this may not have been trimmed enough, and there is the potential that precip may not begin until after sunrise Saturday morning, particularly across the Rt 11 and US-1 corridors.

Warm air advection will continue aloft, though sfc temps will remain below freezing under a shallow cold dome of air. Any untreated elevated roadways may quickly ice up as freezing drizzle/rain moves in.

It remains difficult to differentiate between sleet and freezing rain chances and with such a defined warm nose such as seen on NAM/GFS forecast soundings and a clear CAD setup, sleet is definitely in the realm of possibility.

QPF amounts are overall light with this system, particularly during the time in which wintry precip types are possible. Therefore, not anticipating any large ice accretions or sleet accumulation, but just enough icing is possible to create slick travel conditions Saturday morning.

The surge of warm air advecting in over the cold snow pack will lead to patchy to areas of fog over the entire areas Saturday morning. South winds will gust upwards of 30-35 mph in the afternoon.

KEY MESSAGE 2... 2) Above normal temperatures dominate through next week, and could lead to snow melt and river/lake ice rot.

KEY MESSAGE 2 DESCRIPTION... After a surge of warm air starting Saturday, a weak cold front passes the area Sunday morning bringing rain in the north. Temps increase throughout the day on Sunday getting up to low 40s north and upper 40s to the south as a ridge pushes into the area. Southerly flow continues Monday and Tuesday keeping the warming trend going, getting into the mid to upper 50s. Nightly temperatures will generally only get down to near freezing from Sunday night through Tuesday evening, though some areas in the north could see upper 20s over this period. Warm daytime temperatures could lead to snow melt and ice rot with only near freezing lows limiting refreezing, but could lead to areas of black ice on roads and surfaces.

KEY MESSAGE 3... 3) Potential for a storm Wednesday into Thursday, that could bring rain/snow and chances for wintry mix.

KEY MESSAGE 3 DESCRIPTION... Models are converging on a shortwave low pressure system moving into the area, with a warm front passing through Wednesday before the cold front passes through into Thursday. The shortwave brings chances of precipitation Wednesday/Thursday, though the exact timing and strength of the low and precipitation types are still uncertain. Models suggest a transition between rain and snow in the forecast area, with a chance of wintry mixed precip. Antecedent temperatures are warm Tuesday into Wednesday after above average temperatures to start the week, which may limit frozen precipitation accumulations, though there is still high uncertainty this far out in the forecast. This system will continue to be monitored over the next several days.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Today...VFR for all terminals this afternoon. N 5-10kts.

Tonight...VFR at Aroostook terminals with MVFR possibly sneaking into Downeast terminals after 06z tonight with cigs dropping to near 015 by 10z. Light and variable winds.

Friday-Saturday...Brief improvement to VFR Friday afternoon. MVFR/IFR late Friday night with wintry mix by Saturday morning. Patchy to areas of fog will bring IFR vsbys to terminals on Saturday. SE 5-10kts Friday becoming S 5-15kts with gusts 20-25kts Saturday afternoon.

Sat night - Sun...Improvement to VFR. Winds shift W winds 5 to 10 kts with gusts to 20 kts.

Sun night - Mon...VFR across all terminals. SW winds 5 to 10 kts with gusts to 25 kts.

Mon night - Tue...VFR across all terminals. W winds 5 to 10 kts with gusts to 20 kts.

MARINE

SCA in effect for the outer waters through the day on Friday, and possibly needing to be extending for seas into Friday. Winds briefly drop below small craft levels during the day on Friday and into Friday night before increasing toward gales Saturday afternoon.

Winds will begin to increase on Saturday with the passage of a low pressure system, and there is increasing confidence gusts will increase to gales by Saturday night, then taper once more into the day on Sunday. SCA criteria may then continue into the early part of next week. Mild air temperatures will limit any chance of freezing spray development.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 7 PM EST Friday for ANZ050-051.