Marine Weather and Tide Forecast for Castine, ME

KEY MESSAGES
1. Temperatures start the day below freezing today followed by scattered rain and snow showers from mid morning into the afternoon.

2. A generally dry week with a slight (15-25%) chance of precipitation on Wednesday.

3. A complex upper-air pattern leads to uncertainty by late week.

DISCUSSION
KEY MESSAGE 1 DESCRIPTION...

Colder and drier air works into the area early this morning with temperatures bottoming out in the 20s north to low 30s south during the pre dawn hours. Skies will start off mostly sunny this morning before an approaching trough axis and cold pool aloft leads to cu development by mid morning. Surface heating combined with cold air aloft will yield around 100 J/kg of MU CAPE leading to rain and snow showers. Surface temperatures will likely be too warm to support snow to the surface along the coastal plain while some graupel cannot be ruled out with freezing levels around 2500 feet. Farther inland there will be better chances for heavier snow showers that could put down a quick coating and reduce visibility with this activity most likely from late morning through the afternoon. High temperatures today will range from the mid 30s north to upper 40s along the coastal plain. Cloud cover will diminish with the loss of heating this evening. High pressure building in tonight will favor radiational cooling with lows ranging from the teens north the mid 20s south.

KEY MESSAGE 2 DESCRIPTION...

After a hard freeze on Tuesday morning, a moderating trend should commence as we head deeper into next week. Tuesday currently looks dry with some subsidence behind Monday's trough. Increasing clouds are likely by late on Tuesday ahead of a weak disturbance.

A difficult-to-time shortwave on northwest flow aloft brings the next chance for precipitation to us on Wednesday. With POPs only hovering around 15-25%, it does not look like a washout by any means. With 700 mb temperatures still lingering near or below -10C, it will be cold enough for interior zones to see some scattered light snow, but this appears to be a low-impact event.

KEY MESSAGE 3 DESCRIPTION...

Height rises late in the week suggest temperatures will rebound close to seasonal averages with generally 50s in the forecast for late week (40s in the higher terrain). If any day ends up fully sunny, there is a chance the warm spots could reach the 60s. Overall this looks like a pleasant and dry stretch.

As we head towards next weekend, uncertainty and model spread becomes evident. A complex upper-level pattern is expected to evolve with northern Atlantic blocking, featuring a rex block of sorts from Nova Scotia up to Greenland. For our sensible weather, we will be on the west edge of a stalled cut-off trough, and the east-west placement amongst guidance remains high. Between the spatial and temporal differences, forecast confidence is much lower than normal.
What can be extracted currently is a continuation of near seasonable temperatures and a slight increase in precipitation towards 20-30% by Sunday. Stay tuned for much more certainty in the coming days as the upper-level timing and placement of multiple features are resolved.

AVIATION /10Z MONDAY THROUGH FRIDAY/
Mainly VFR conditions are expected today and tonight, although scattered RA and SN showers may result in brief localized vis restrictions.

Outlook:

Tuesday: VFR conditions expected.

Tuesday Night: Becoming MVFR or IFR CIGs . Low confidence in VIS forecast, but some light snow is possible for portions of the forecast area, especially away from the coast.

Wednesday: Becoming VFR conditions.

Thursday: VFR conditions expected.

Thursday Night: VFR conditions expected.

Friday: VFR conditions expected.

MARINE
Winds turn more westerly through daybreak with gusts diminishing below 25 kts. High pressure gradually builds in late today through Tuesday with winds and seas remaining below SCA thresholds.

High pressure shifts southeast of the waters Tuesday night with a warm front approaching Wednesday. This will shift winds more southerly and then southwesterly while winds generally stay below 25 kts and seas below 5 feet. Will have to keep an eye on marine fog/stratus formation Tuesday night into Wednesday with the warm front approaching. High pressure then looks to return around Thursday into Friday.

GYX WATCHES/WARNINGS/ADVISORIES
ME...None.
NH...None.
MARINE...None.