textproduct: Gray - Portland

WHAT HAS CHANGED

Minor edits to PoPs with this update based on latest trends.

KEY MESSAGES

1. Slippery travel expected in spots early this morning and then again later this afternoon and evening. Some light snow is also possible near the NH/MA border during this time as well as low pressure scoots to our south. However, chances for an impactful snow seem low at this time as the bulk of precipitation is expected to remain over southern New England with marginal temperatures in places over southern NH.

2. Expect an active mid to late work week with multiple precipitation chances and temperatures around or a bit below normal for late March.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

As low pressure departs to our southeast today a shortwave trough will quickly approach from the west. This will aid in pressure falls across northern New England, with an inverted trough emanating from the departing SFC low developing. This will help increase snow shower chances as the day progresses. This looks to be especially true, especially in NH later this afternoon and evening with most CAMs in agreement that the inverted trough will form in N-S fashion there. This will act to organize snow showers which could be heavy at times, possibly affecting the evening commute in a relatively narrow band in the state. Slippery travel is possible, with a chance that an impact-based winter weather advisory will be issued for the commute depending on how organized the potential band gets. Several inches of snow may fall in a relatively narrow N-S corridor. Another batch of heavier accumulating snow showers may also form across central zones northward to the mountains. However, no one is out of the woods yet due to the somewhat unpredictable mesoscale nature to the system.

The snow showers will dissipate later in evening. Fair weather is then expected for Tuesday.

KEY MESSAGE 2 DESCRIPTION...

On Wednesday, a cold front looks to move southeastward across NH and Maine. Instability ahead of the front could lead to the development of snow squalls in the afternoon, especially in the mountains. Snow squalls could lead to some slick mountain passes Wednesday evening.

By the end of the week, ensembles are perhaps a little more confident in a much broader low moving from west to east Thursday night and into Friday. While models are more confident in the existence of the system, models are less confident on precipitation types. Rain appears more likely across southern New Hampshire but measurable snowfall could be possible across the mountains and north.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Through 12Z Tuesday...IFR to LIFR ceilings remains possible this morning with occasional visibility reductions in light snow, fog, or drizzle. Ceilings will then lift to MVFR by this afternoon, but snow showers are expected to increase this afternoon and evening that could produce IFR visibilities. Snow will taper off in western ME this evening and then a little later across NH. A gradual return to VFR is expected tonight.

Outlook (Tuesday through Friday):

Tuesday: VFR likely.

Tuesday night - Wednesday: Brief periods of IFR possible under snow showers.

Wednesday night - Thursday night: IFR possible in rain and snow.

Friday: Improving to VFR with possible restrictions lingering in the mountains.

MARINE

SCA conditions continue in east-northeasterly flow through tonight, with marginal gale force gusts possible across the eastern waters.

An active pattern is expected to continue through mid to late week, which will result in nearly continuous southwesterly SCA conditions. There is also a low chance for gale force wind gusts Wednesday through Thursday depending on the location and strength of developing low pressure over or just east of the Gulf of Maine.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory until 8 AM EDT Tuesday for ANZ150-152-154. Small Craft Advisory until 2 PM EDT this afternoon for ANZ151.