textproduct: Gray - Portland

WHAT HAS CHANGED

The gale warning for Casco and western Penobscot Bay has been cancelled and a small craft advisory has been issued in its place.

The Coastal Flood Advisory has also been cancelled as the tide cycle has already peaked. We will monitor trends and see if another may be needed for this morning's high tide.

KEY MESSAGES

1. Minor coastal flooding remains possible during this morning's high tide cycle.

2. Cold temperatures are expected tonight due to strong radiational cooling conditions.

3. Expect a slight cooling trend Wednesday through Friday before the next push of arctic air arrives on Saturday. A few weak disturbances will lead to some periodic light snow chances.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION... High astronomical tides combined with between 1-2 ft of storm surge from distant low pressure over the open North Atlantic may bring total water levels to near minor flood stage during this morning's high tide cycle at around 11 AM. Increased wave action may also result in some minor beach erosion.

KEY MESSAGE 2 DESCRIPTION... Surface high pressure will move across the region tonight, allowing for mainly clear skies and light winds. This combined with the existing snowpack will allow for a cold night. Used MOS guidance for overnight lows, which brings some interior northern valleys down to around 20 below. Elsewhere, lows into the single digits either side of zero are likely.

KEY MESSAGE 3 DESCRIPTION... By Wednesday, we will transition into southwest flow aloft as a weak shortwave/upper low approaches and surface high pressure slides out. The upper low will gradually track from just north of Ottawa early Wednesday morning to the crown of Maine and vicinity by the evening. Some isolated to scattered snow showers will be possible as the disturbance moves through, especially across the mountains and vicinity.

Two more waves will quickly move through on Thursday and Friday with persistent troughing in place across the region through the end of the week. Any snow showers on Thursday will likely be confined to the mountains and vicinity but the Friday wave looks to be a bit stronger and could lead to our next widespread light snow. Currently, the NBM is suggesting widespread low to medium chances for light snow across much of New Hampshire and western Maine, potentially hanging on through the weekend.

High temperatures on Wednesday will generally be around normal for this time of year outside of the mountains. Readings will mainly be in the lower 20s to lower 30s but some teens are likely in the mountains. Then as persistent troughing sets in, we cool down slightly on Thursday and Friday with forecast highs maxing out in the mid to upper 20s. Confidence then continues to increase that the next push of arctic air will settle back in through at least the rest of the weekend.

AVIATION /06Z MONDAY THROUGH FRIDAY/

Through 06Z Tuesday...VFR prevails through tonight with no significant wind gusts or wind shear expected.

Outlook:

Tuesday - Tuesday night: VFR Expected with light and variable winds.

Wednesday - Wednesday night: MVFR possible north, VFR more likely elsewhere. Snow showers possible.

Thursday - Friday: VFR expected south, MVFR possible north.

Friday night - Saturday: MVFR and snow showers possible.

MARINE

Northerly winds will continue to diminish through today but seas will remain elevated outside of the bays through Tuesday morning, likely necessitating a small craft advisory.

High pressure extends across the waters for much of the remainder of the week, with the next cold front likely on Friday.

GYX WATCHES/WARNINGS/ADVISORIES

MARINE...Gale Warning until 7 AM EST Monday for ANZ150-152-154. Small Craft Advisory until 7 AM EST Monday for ANZ151-153.