textproduct: Caribou

WHAT HAS CHANGED

- Confidence increasing in a small snow event with localized 1-3 inches of snow over portions of Downeast Wednesday afternoon/evening.

KEY MESSAGES

1) Minor coastal overwash possible at high tide tonight and Monday morning.

2) Wednesday afternoon/evening, minor snow accumulation possible Wednesday, with the best chance Downeast.

3) For the weekend, likelihood of colder weather and breezy conditions, and the possibility of a winter storm.

DISCUSSION

KEY MESSAGE 1... Minor coastal overwash possible at high tide tonight and Monday morning.

KEY MESSAGE 1 DESCRIPTION... As a strong low pressure system passes south of the Gulf of Maine and Nova Scotia, a tightened pressure gradient on the northern edge of the system will lead to gusty winds for our area, particularly the southern half of the CWA, beginning tonight and lasting through the day on Monday. Breezy winds could reach as high as 30 to 40 mph along the coast. A northeast long-period swell generated by the strong low pressure system will coincide with the highest tides of the month, which could cause overwash at vulnerable areas along the coast. These effects will be most notable at the Monday morning high tide. Pedestrians and motorists should use caution along shorelines.

KEY MESSAGE 2...Minor snow accumulation possible Wednesday afternoon/evening, with the best chance Downeast.

KEY MESSAGE 2 DESCRIPTION... An upper level low pressure approaches from the west Wednesday, with probably weak surface low development around the Maine coast. The upper low could brings a slight chance of snow showers to the entire area, but it's the surface low along the coast that is of more concern. Depending on the track and strength of this surface low, 1-3 inches of snow is possible Wednesday afternoon/evening, with the best shot of this occurring being Downeast, especially south/east of Bangor. This is not a strong system by any means and it doesn't have much moisture to work with. That said, one thing that stands out is notable low and mid-level instability up into the dendritic growth zone, with steep lapse rates. This means there could be locally heavy snow showers, and am a bit concerned that as this system comes within range of the CAMs, this system may be looking more impressive. Did go higher that NBM for PoPs/QPF Downeast, but kept PoPs below likely levels for now. Any precipitation that does fall will fall as snow, as a low density snow at that.

KEY MESSAGE 3...For the weekend, likelihood of colder weather and breezy conditions, and the possibility of a winter storm.

KEY MESSAGE 3 DESCRIPTION... A volatile setup over the region this weekend. A vigorous upper trough will be amplifying as it dives southeast out of Canada toward us, with bitterly cold Arctic air moving in as well. Somewhere over our general region, a likely strong surface low forms and potentially stalls out as the upper trough becomes a slow-moving cutoff low. There is a lot of model disagreement on where this cyclogenesis happens and where the upper low stalls out, but somewhere over Maine or points east toward Prince Edward Island could get a substantial snowstorm out of this, with blizzard not out of the question. The majority of solutions favor areas a bit to our east to get the heavy snow and strongest winds, with the cyclogenesis happening just a bit too far east to nail Maine. However, a notable minority of solutions are further west and do hit Maine hard with snow and wind. Either scenario strongly favors snow over rain as a precipitation type. This system has a potentially high ceiling, meaning a foot of snow and strong winds could happen. That said, we may only end up with some wind and light snow showers if the storm gets its act together too far east, and this is what the majority of solutions are presently showing. It is definitely worth keeping in touch with forecasts for the weekend to see how things trend. Many times these storms don't pan out. For example, many models had a substantial system for today (Sunday), but instead it hit North Carolina with substantial snow and is passing offshore and missing us. Wind chills could also be a concern next weekend, with the potential for readings colder than 20 below.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

Tonight through Monday night... Northern terminals: MVFR cigs may shift into the area from the east through this afternoon. These high-end MVFR cigs will only last for a few hours before scattering out this evening. Another round of MVFR cigs may move in from the west after midnight tonight, and lead to another period of MVFR, possibly even brief IFR cigs, prior to these cigs scattering out around sunrise. N winds 5 to 10 kts with gusts 20 to 25 kts, tapering through Monday night. LLWS possible tonight, especially at KHUL.

Downeast terminals: VFR conditions could give way to high end MVFR this evening as the edge of a lower cloud deck around the low passing to the south scrapes the forecast area. It is possible ceilings could remain VFR through this time, and the duration of any MVFR will likely only be a few hours before scattering out into the early morning hours on Monday. VFR then continues through Monday into Monday night. N winds 10 to 15 kts with gusts 20 to 25 kts, tapering through Monday night. LLWS expected overnight tonight.

Tuesday and Tuesday Night...VFR or MVFR. Lower confidence than usual due to uncertainty on whether an MVFR ceiling will be present. About a 50 percent of MVFR conditions for FVE/CAR/PQI/HUL, and a 25 percent chance at BGR/BHB. Variable wind 5 kts or less.

Wednesday-Wednesday night...Mix of MVFR and VFR, with a chance of snow. NW wind 5-10 kts.

Thursday...VFR with MVFR possible northern terminals. NW wind 5-10 kts.

Thursday Night/Friday...MVFR or VFR. W/SW wind 5-10 kts.

MARINE

Long-period NE swell increasing to around 11 seconds tonight into Monday morning with seas 4 to 10 ft with N wind gusts increasing to 35 to 40 kts across all waters. These winds will persist through Monday before tapering Monday night. Light freezing spray expected with possible brief moderate freezing spray late tonight.

Next shot at small craft winds (about a 75 percent chance) comes Wednesday night as a NW wind, but generally speaking, looking for conditions under small craft levels Tuesday to Friday. Next weekend, likelihood of N/NW gales with possibility of storm force winds.

CAR WATCHES/WARNINGS/ADVISORIES

ME...None. MARINE...Gale Warning until 10 AM EST Monday for ANZ050>052.