Marine Weather and Tide Forecast for Falmouth, ME

KEY MESSAGES
1. While not as breezy as last night, it will again feel like the teens and 20s below zero tonight across much of New Hampshire and western Maine. Elevated locations will be more exposed to wind overnight, while valley locations cool quickly this evening under clear skies and calmer winds.

2. Light snow looking more likely Tuesday night into Wednesday.
The timing may be such that it impacts the evening commute on Tuesday and the morning commute Wednesday.

DISCUSSION
KEY MESSAGE 1 DESCRIPTION...
Another night of Cold Weather Advisories in store as frigid airmass remains overhead. Wind magnitude and coverage will be lesser tonight as a weak embedded shortwave cuts through the forecast area and out to the Gulf of Maine. With clear skies overhead, tonight's cold will come in two flavors: wind chill or well below zero temperatures.

Where wind isn't as strong in valleys and locations south and east of the foothills, radiational cooling will be possible.
Once winds slacken from daytime mixing, will look for isolated locations to quickly decouple and temps to start falling. There is some uncertainty how strong of an effect this will be given 925mb winds off the surface still well represented in cyclonic flow. Hence the isolated nature of raw temperatures truly falling off.

Given the spread of lighter winds amid the cool air mass, Cold Weather Advisories should handle the expected teens to 20s below zero apparent temperatures tonight. These will likely be met late tonight and early Mon morning as winds pick back up due to mixing.

Even though temperatures will rise into the mid 20s for points outside of the mountains, renewed breeze will still make it feel like the teens through the day Monday. For Monday night, high pressure will be nearing overhead with much calmer winds and clear skies. For this, brought in cooler temperatures in anticipation of much better radiational cooling conditions.
However, overnight values should not reach criteria for cold weather headlines.

KEY MESSAGE 2 DESCRIPTION...
Incremental change in modeling for the Tue night snowfall. That change has been in the more likely direction, and NBM guidance is now fairly widespread likely PoP. I did not see much reason to deviate from that. Over the next couple of days we may still see guidance wobble around regarding how far east the best lift advances before getting undercut by the approaching shortwave.
For that reason I am hesitant to go all in with categorical in any given location. "Snow likely" covers the messaging at this time.

What we do know is that the mid level warm front will lift into the forecast area Tue evening. Warm advection over that frontal boundary will provide the lift thru a saturated snow growth zone. Forecast soundings and ensemble QPF suggesting this is largely a light snow event, but there may be occasional bursts of moderate especially in the 7p to 1a window. As things stand right now that means snow is beginning during the evening commute and accumulations are likely on untreated surfaces.

Based on ensemble median QPF, the most likely solution (80 percent) is between 2 and 4 inches of snow in a swath thru much of the forecast area. The 10th and 90th percentile amounts push that to maybe 1 to 5 inches, so in this case the goalposts really seem to have narrowed.

One aspect that has changed a bit is heading into Wed the surface trof lingers over the forecast area. This is keeping snow or snow showers going into the middle of Wed on some guidance. So chance PoP is maintained for most of the day.
However any more detail on an inverted trof at this range is going to be extremely likely to change in the coming days.



AVIATION /00Z MONDAY THROUGH FRIDAY/
Through 00z Tuesday: VFR with some MVFR ceilings towards HIE.
There is some uncertainty on how much coverage these clouds produce. There will be a lower jet of 40kt winds moving through tonight, creating some LLWS for most interior terminals. LLWS should slacken Mon morning as surface winds again pick up due to mixing.

Outlook...

Monday Night: VFR with no sig wx.

Tuesday: IFR or lower conditions developing later in the day.

Tuesday Night: IFR or lower conditions in light snow.

Wednesday: Widespread IFR ending, but lingering local IFR or lower possible in snow showers.

Wednesday Night: VFR conditions expected.

Thursday: VFR conditions expected.

Thursday Night: VFR conditions expected.

Friday: VFR conditions expected.

MARINE
Gale conditions persist towards the Midcoast through this evening, with most other coastal waters locations underperforming on winds today. SCAs have been expanded with some continued gusts 25 to 30 kts through tonight and Mon morning. Freezing spray remains a hazard as well as long as sufficient winds are in place.

Winds and seas will continue to diminish Tue and remain below SCA thresholds. Towards the weekend conditions well outside the bays may approach marginal SCA criteria, but largely expecting the majority of the marine zones to stay below headline.

GYX WATCHES/WARNINGS/ADVISORIES
ME...Cold Weather Advisory until 10 AM EST Monday for MEZ007-012- 018-019-033.
NH...Cold Weather Advisory until 10 AM EST Monday for NHZ001>011- 015.
MARINE...Gale Warning until 2 AM EST Monday for ANZ150.
Freezing Spray Advisory until 7 AM EST Monday for ANZ150>154.
Small Craft Advisory until 4 PM EST Monday for ANZ151>154.