textproduct: Gray - Portland

WHAT HAS CHANGED

The threat for ice jam flooding has decreased with the return of colder temperatures.

KEY MESSAGES

1. Dry conditions are expected through Thursday with below average temperatures.

2. Light precipitation looks to be the story for the second half of the week through the weekend, with drier weather following to start next week. No impacts are expected at this time.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION... Canadian high pressure will crest over New England today, allowing for partly to mostly sunny skies. Despite the sunshine, h850 temperatures will only be around -15C, which will limit high temperatures to the 20s and 30s from north to south. While it will not be as windy as yesterday, west-northwest gusts up to around 25 mph will make it feel even colder.

High pressure will exit to the east tonight, with developing light southerly flow. Low temperatures will generally be into the teens and lower 20s but a few interior valleys may get into the single digits.

Thursday will feature more in the way of cloud cover as a frontal boundary and accompanied H5 s/wv trof axis approaches from the west. It should be another dry day though with high temperatures a few degrees warmer into the 30s to middle 40s from north to south. Southeasterly wind gusts up to around 25 mph will be possible.

KEY MESSAGE 2 DESCRIPTION... A frontal boundary begins to sag southward into New England Thursday night. At that point a sharp shortwave trough passes bringing northwest flow and mainly confining snow showers to the mountains as dry air remains in place to the south. The frontal boundary continues to make southward progress on Friday before stalling Friday night. This will allow any rain shower activity to expand to the rest of the area during the day with a shortwave providing additional forcing Friday night. Temperatures look to drop back below freezing Friday night so this is the best chance for more widespread light snow showers. Shower chances on Saturday are a little less certain as ensemble solutions are beginning to favor the front making enough progress that forcing ends up south of our area, but until we see a bit more agreement it is fair to keep a chance of showers in the forecast. There is even more uncertainty Sunday as model camps diverge on a low track. The Euro camp has low pressure taking a more northerly track that gets the front moving again and pushes it through fairly quickly resulting in the least amount of QPF. The GFS camp has low pressure riding the frontal boundary through our area which would result in more QPF as likely for a longer duration through Sunday night and maybe into Monday. The Canadian camp falls down the middle, favoring a northern track but with a closer pass than then Euro. Bottom line all camps favor some degree of precipitation, but amounts and timing are a little more questionable at this time range.

Following this ensemble solutions favor high pressure moving in to start next week. Don't expect a warm up with it though because the 500 mb pattern remains mean troughing, so northwesterly flow is going to keep temperatures right around normal with highs in the 30s and 40s and lows in the teens and 20s.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

Through 06Z Thursday: VFR conditions are expected. W-NW winds will prevail today with gusts up to 25 kts possible. Winds will become southerly tonight at 5-10 kts and then southeasterly on Thursday at 15-20 kts. No LLWS is anticipated through the period.

Outlook...

Thursday night: VFR conditions expected for most terminals but MVFR CIGS are possible at KHIE due to SHRASN.

Friday through Sunday night: Light rain and/or snow showers can't be ruled out which would bring some MVFR conditions, but VFR would be expected otherwise.

MARINE

While westerly wind gusts will fall mainly below 25 kts by this morning, seas will remain elevated through tonight and therefore an SCA has been issued through early Thursday morning.

Waves finally begin to settle Thursday night and we may get a brief period of fair conditions through the day Friday. Friday night waves build again, with wind gusts following behind on Saturday as a front approaches the waters. With the front stalling in the area it looks like SCA conditions could persist through at least Monday night with conditions beginning to improve Tuesday as high pressure moves over the waters.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...Small Craft Advisory until 8 AM EDT Thursday for ANZ150-152- 154. Small Craft Advisory until 8 PM EDT this evening for ANZ151- 153.