textproduct: Caribou

WHAT HAS CHANGED

- (7PM Update) Changes to PoPs, QPF, and snow amounts were made. The rain/snow line moves northward slightly faster, with mainly rain expected along the immediate coast and coastal waters. QPF has trended lighter over the past couple cycles also, especially for Thursday night where nearly all guidance aside from the Canadian suite now has the north drying out faster and the heaviest precipitation either over the southern half of the area or missing the area nearly completely just to the south. Updates to the aviation discussion and key message 1 were also made.

KEY MESSAGES

1) Snow changing to rain is expected late tonight through Thursday evening. Snow may impact the Thursday morning commute, mainly from Bangor and Interior Downeast northward.

2) Much cooler than average temperatures Friday through Sunday. Wind chills Friday night will get as cold as about 15 below in the north, with increased threats of frostbite.

3) Light rain and snow possible Monday, along with gusty winds. Travel impacts are possible in the north due to icy roads.

4) Active weather pattern likely starting Wednesday, with potential for wintry precipitation.

DISCUSSION

KEY MESSAGE 1... Snow changing to rain is expected late tonight through Thursday evening. Snow may impact the Thursday morning commute, mainly from Bangor and Interior Downeast northward.

KEY MESSAGE 1 DESCRIPTION... Low pressure will approach from the west tonight drawing a warm front north across the forecast area. Overrunning precipitation will develop across the region tonight. Across northern areas, expect precipitation in the form of snow. Across Downeast areas snow will transition to a snow/rain mix late tonight. The low will track across northern Maine Thursday drawing warmer air northward across the forecast area. Precipitation will transition to all rain across central and Downeast portions of the forecast area through Thursday morning. Across northern areas, snow should mix with rain during the afternoon. The low exits across the Maritimes Thursday night drawing a cold front south across the forecast area. Low pressure could cross the Gulf of Maine Thursday night moving along the exiting cold front. Colder air will allow a transition back to snow, from north to south across the forecast area, Thursday night. Storm total snow accumulations across far northern areas from later tonight through Thursday night will generally range from 2 to 4 inches. However, locally greater totals could occur across higher terrain areas and location where snow remains the predominant precipitation type. Across Downeast areas, snow accumulations tonight will be around an inch or less. An additional inch or less is also possible later Thursday night after the transition back to snow.

KEY MESSAGE 2...Much cooler than average temperatures Friday through Sunday. Wind chills Friday night will get as cold as about 15 below in the north, with increased threats of frostbite.

KEY MESSAGE 2 DESCRIPTION... Cold Friday through Sunday. Not quite record-level cold, but quite a bit colder than average. Friday will be breezy from the northwest as the previous system exits. The coldest of the airmass moves in Friday night. With a northwest breeze persisting, wind chills should get below zero for most areas, and to around 15 below over the north. Winds ease for Saturday into Sunday, but it stays cool. Highs on Saturday will only be 15-20 above in the north and in the mid to upper 20s Downeast. Warming trend begins Sunday as highs will be above 10 degrees warmer than Saturday. Generally dry Friday through Sunday, though can't rule out an isolated snow shower mainly during daytime hours.

KEY MESSAGE 3...Light rain and snow possible Monday, along with gusty winds. Travel impacts are possible in the north due to icy roads.

KEY MESSAGE 3 DESCRIPTION... A fast-moving system in upper level west/northwest flow is likely to bring light precipitation and rapid temperature changes around Monday. Snow or rain changing to snow appears likely early Monday with a warm front, with the best chance of any accumulating snow being in Northern Maine. If any snow does occur in the north, it should be less than 2 inches, though it could impact the Monday morning commute. Warmer air is likely to move in, with any snow changing to rain. Then colder air moves back in Monday night with rain possibly changing to a little snow before ending. Again, we are talking light snow accumulations likely less than 2 inches and mainly in the north. Precipitation overall with the Monday system looks light, with a 75 percent chance of precipitation not exceeding one quarter inch. Winds look breezy with gusts around 30 mph with the system, but very unlikely strong enough to be impactful. Will have to keep an eye out for the potential for a flash freeze of any wet roads late Monday night as colder air rushes back in on the back side of the system.

KEY MESSAGE 4...Active weather pattern likely starting Wednesday, with potential for wintry precipitation.

KEY MESSAGE 4 DESCRIPTION... While this is still well out in the future, there is a strong signal for active weather Wednesday/Thursday of next week. More concerning is the setup appears conducive to cold air damming, as there will be strong zonal flow aloft and a much warmer airmass probably just to the southwest of the region, and Arctic high pressure centered to our north. This could set the stage for several rounds of mixed precipitation somewhere in the Northeast, with significant snow, sleet, freezing rain, and rain all being in play. Looking at individual members of various ensemble systems, the majority have sleet and/or freezing rain somewhere in the Northeast region Wednesday and/or Thursday. Timing, magnitude, and location vary significantly though. Way, way too far out to get into details, but definitely something to watch.

AVIATION /00Z THURSDAY THROUGH MONDAY/

Tonight...VFR early. IFR/LIFR late with snow developing, quickly changing to rain at coastal terminals and mixing with rain at KBGR late. Light and variable winds early, becoming south/southeast 10 to 15 knots with gusts to around 20 knots. Southerly low level wind shear develops after midnight.

Thursday...IFR/LIFR improving to MVFR north and VFR Downeast late. Snow in the morning changes to rain and tapers off across the north. South/southeast winds 10 to 15 knots with gusts up to 20 knots, becoming southwest 5 to 10 knots. Southerly low level wind shear during the morning.

Thursday night...High uncertainty with the northern extent of low clouds and RA. MVFR likely, with IFR and steady RA most likely along the coast. Some improvement is possible late, mainly across the north, where VFR is possible late. NW winds 5 to 10 kts.

Friday and Friday night...VFR. NW winds 10-15kt gusting 20-30kt, diminishing to 5-10kt late Friday night.

Saturday through Sunday...VFR. W winds 5-15kt.

Monday...Potential for MVFR/IFR with light rain and snow, mainly northern terminals. SW winds 10-15kt gusting 25kt.

MARINE

A Small Craft Advisory remains in effect through 00Z Friday for all the waters. Small craft advisory level seas will persist Thursday night. Rain develops later tonight with a break during the day before another round of rain moves in Thursday night.

N/NW small craft winds likely Friday night. Can't rule out low- end gales. Light freezing spray also likely late Friday night and Saturday morning. Lighter winds late Saturday to early Sunday. Then SW gales likely (75 percent chance) Monday. Seas 5 to 7 ft early Friday, gradually subsiding to 1 to 3 ft Saturday night. Seas then build to somewhere around 10 ft Monday.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Small Craft Advisory until 8 PM EDT Thursday for ANZ050>052.