textproduct: Gray - Portland

WHAT HAS CHANGED

A Cold Weather Advisory has been issued for much of New Hampshire and portions of western Maine tonight into Friday morning. Wind chills have trended cooler for these regions as winds remain breezy overnight in cold advection.

No significant trends in the coastal low with a close approach to Southern New England with periphery minor coastal impacts still in the cards.

640am Update...Added the mention of scattered snow showers NW of the Whites today as moisture advects eastward. Downslope drying should limit how much of this activity makes it into the foothills or interior, but can't rule out a few flakes falling this afternoon.

KEY MESSAGES

1. Below normal temperatures continue through Friday. A Cold Weather Advisory has been issued for much of New Hampshire, far southern Maine, and the western Maine mountains for tonight into Friday morning. This is due to wind chills falling into the double digits below zero. These temperatures can cause frostbite to exposed skin in as little as 10 to 30 minutes.

2. A strong coastal low may bring impacts to the coast on Sunday, but most guidance favors a track far enough offshore to keep the impacts minimal.

3. Marine weather impacts are expected Sunday into Monday as the close approaching coastal low brings Gale/Storm force winds.

4. High Astronomical Tides Sunday through Monday and the close approaching coastal low provide a threat for minor coastal flooding late this weekend into Monday.

DISCUSSION

KEY MESSAGE 1 DESCRIPTION...

Cold weather continues today with highs in the teens to lower 20s depending on location and elevation. Otherwise fair weather is expected with a mix of sun and clouds. A reinforcing shot of cold air arrives later this afternoon and evening from the northwest. Winds will increase some, and temperatures will drop. As such, a Cold Weather Advisory has been issued for our much of NH, the western Maine mountains, and interior York Co for wind chill values lowering to around -20 to -25F tonight.

Other than mountain snow showers on Saturday, it's just continuing cold with wind chills around zero most of the day on the coast and -10F well inland.

KEY MESSAGE 2 DESCRIPTION...Global models continue to advertise a strong coastal low lifting to the north-northeast offshore of the eastern seaboard Sunday into Sunday night. Over the last 12 hrs ensemble mean guidance hasn't shown any large trends between the GEFS and EPS camps, with a slight trend further east in the GEFS with the EPS staying steady, or just the slightest trend back eastward with the mean surface low. One slightly interesting observation was the 18z EPS did have a few more outliers further west after a constant shift eastward over the past 48hrs. Not enough of a signal to make a change in the forecast, still looks like periphery coastal impact event, mostly on the wind, seas, and coastal flood side of things. Not expecting much of any snowfall impacts, but will continue to watch any noticeable trends over the next 24hrs.

KEY MESSAGE 3 DESCRIPTION...Even though land based impacts Sunday through Monday look to be limited with the storm passing offshore to our south, marine impacts are still possible, if not likely. Gale force winds are looking likely at this point with a strong pressure gradient on northerly winds between the ridge over Quebec and the deep surface low south of the Gulf of Maine. Offshore flow will limit large waves to the outer coastal waters.

KEY MESSAGE 4 DESCRIPTION...High Astronomical Tides are expected Sunday through Monday with a 10.9 MLLW tide at Portland during both Sunday and Monday morning. It will only take a foot to foot and half of storm surge for minor inundation flooding. Fortunately it looks like the peak surge will occur on Sunday afternoon/evening, with the lower of the two daily high tides, in addition, nearshore waves with the more north to northeast winds won't be a huge factor. Will have to watch the NH seacoast with a slightly more favorable fetch. Overall feel this will be a worst case flood advisory event at this time, but will have to watch closely.

AVIATION /12Z THURSDAY THROUGH MONDAY/

Through 12z Friday...VFR conditions are expected this morning through Friday for much of the area. Exception will be terminals NW of the mountains where periods of light SHSN and MVFR ceilings rotate through. WNW winds increase later this morning, particularly across central ME and the western ME mountains. Can't rule out some flurries and MVFR bases during the afternoon through southern NH and ME, but vis restrictions are unlikely SE of the mountains. Winds and SHSN slacken this evening, but remain breezy.

Outlook:

Friday night through Saturday night - VFR conditions with continued cold weather.

Sunday through Monday - Coastal low tracks south of the area, with gusty winds on Sunday, but overall ceilings and visibilities will stay above MVFR

Monday Night through Wednesday - Quiet weather with VFR conditions expected.

MARINE

Through Friday...Northwesterly winds are expected through tonight. With another shot of cold air once again overspreading the waters later today and tonight, SCAs have been issued along with freezing spray advisories.

Outlook:

Friday night through Saturday night - Quiet weather over the coastal waters with light winds.

Sunday through Monday - Strong coastal low tracks south of the Gulf of Maine, bringing a period of Gale or Storm Force Winds.

Monday Night through Wednesday - High pressure in control with limited marine weather impacts expected.

GYX WATCHES/WARNINGS/ADVISORIES

ME...Cold Weather Advisory from midnight tonight to 10 AM EST Friday for MEZ007>009-018. NH...Cold Weather Advisory from midnight tonight to 10 AM EST Friday for NHZ001>013-015. MARINE...Small Craft Advisory from 4 PM this afternoon to 1 PM EST Friday for ANZ150>152-154. Freezing Spray Advisory from 7 PM this evening to 1 PM EST Friday for ANZ150>154.