textproduct: Gray - Portland

WHAT HAS CHANGED

Added some low chance PoPs into southern Maine for this afternoon as CAMs have been consistently showing some shower activity making it into that area over the last few runs. Otherwise, the forecast remains on track.

KEY MESSAGES

1. A weak disturbance will lead to some scattered snow showers today, with cooler air returning behind this system for late week.

2. Light snow is possible Friday night into Saturday and could create slippery travel.

3. Becoming bitterly cold and breezy this weekend with Cold Weather Headlines increasingly likely centered around Saturday night. Dangerous wind chills of -20F to -30F possible from Saturday late evening through Sunday morning. Latest forecast soundings indicate not only the invasion of very cold temperatures Saturday afternoon and night, but it may be on a few-hour period of winds bordering on wind advisory.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

A closed low is currently approaching the southern Ontario/Quebec border and will eventually move east across the forecast area later this morning and afternoon. Lift from this low/shortwave will lead to some scattered snow showers through the day. It still looks like most of the showers will be found in the higher terrain, but several CAMs do suggest some activity making it out into central Maine. Any accumulations should be light. A weaker wave will then move through on Thursday. A few more isolated snow showers will be possible across the mountains, but coverage is likely to be more sparse than the Wednesday system.

Regarding temperatures, we could see some more radiational cooling this morning but it will be a trickier forecast than in previous days as clouds will be increasing from west to east. For this package, will continue the trend of colder lows in the valleys east of the mountains as clouds may not really settle in here until late but it could be close. Highs today will generally be around normal for this time of year, ranging form the mid teens to lower 20s across the mountains and northern valleys, to the upper 20s and lower 30s south. Lows will mainly be in the single digits above zero tonight and highs on Thursday will be just a touch cooler, especially across the mountains and valleys.

KEY MESSAGE 2 DESCRIPTION...

No significant changes to the snow forecast for Friday night and Saturday. WAA out ahead of the next arctic air mass will aid in the development of light snow Friday night which will be on and off through Saturday as upper level low pressure moves overhead. The system will the moisture-starved, and with coastal redevelopment occuring well offshore, the chances for anything more than an inch or two at any given location is low.

KEY MESSAGE 3 DESCRIPTION...

The next and probably more important key message is the return or arctic air Saturday into Monday. With the passage of the arctic boundary on Saturday, temperatures will likely steadily fall during the afternoon as winds increase. This will be especially true in the interior.

Latest forecast soundings indicate there is at least moderate potential for wind-advisory criteria gusts Saturday afternoon and night which will of course exacerbate the cold. Bears watch for sure. Saturday night will be pretty brutal.

Temperatures remain below normal but start to recover Monday, and by Tuesday guidance favors returning to near or even slightly above normal temps.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

Through 12Z Thursday...HIE and LEB are seeing snow showers this morning bringing about MVFR/IFR visibilities at times. This activity is expected to move toward AUG and then RKD this afternoon. Snow showers taper off this evening with VFR conditions then prevailing at all terminals through tonight.

Outlook:

Thursday-Friday: VFR prevails.

Friday night - Saturday night: Light snow and IFR restrictions possible. Northwest gusts of 25-35kt possible Saturday afternoon and evening. Possibly up to 40kt at times.

Sunday and beyond: There could be a few snow showers but mainly VFR is expected, except MVFR possible at HIE. Northwest gusts of 25-35kt possible 25 kt on Sunday with improving conditions early next week.

MARINE

A weak low pressure system crosses New England today, with a cold front crossing the waters late in the day. Some marginal SCA conditions will be possible across the outer waters with the passage of the front late this afternoon and evening.

SCA conditions possible late Thursday and Thursday night with improving conditions Friday.

Low pressure slides across New England Friday night and is expected to strengthen south and east of the coastal waters over the weekend. North to northwest gales are likely, including the bays, and it's possible there will be a period of storm-force gusts. Moderate freezing spray is likely over the weekend with heavy freezing spray possible in some locations from late Saturday through Sunday morning.

Gales might linger into Monday with gradually improving conditions Monday night and Tuesday.

GYX WATCHES/WARNINGS/ADVISORIES

ME...None. NH...None. MARINE...None.