textproduct: Boston / Norton

WHAT HAS CHANGED

Confidence is increasing in dangerously cold wind chills, strong wind gusts and heavy freezing spray over the waters this weekend.

KEY MESSAGES

- Mainly dry through Thu with very cold nights. Temperatures trending colder Wed & Thu.

- More active Friday into the weekend. Chance for dangerously cold wind chills this weekend along with strong winds and heavy freezing spray over the waters.

DISCUSSION

Key Message 1...Mainly dry through Thu with very cold nights. Temperatures trending colder Wed & Thu.

A quiet weather pattern continues through the end of the week. A dry cold front crosses the region on Wednesday bringing slightly cooler temperatures to southern New England through the end of the week before a colder shot of arctic air this weekend. High temps Wednesday through Friday generally in the mid to upper 20s with much colder overnight lows generally in the single digits across the region. A dry column will support mainly sunny skies through Friday afternoon.

Key Message 2...More active Friday into the weekend. Chance for dangerously cold wind chills this weekend along with strong winds and heavy freezing spray over the waters.

A generally quiet week ends with a passing Alberta clipper and its strong arctic front passing through the region. As the previous forecast noted, this is expected to be a moisture-starved system that will push through quickly, which will limit any snowfall totals that accumulate. Generally, a coating to an inch can be expected, with the greater chance for an inch mainly along the eastern coastline as ocean effect showers may linger through the day Saturday.

An arctic front moves through southern New England, leaving what may be the coldest wind chills we've seen this season in its wake. The general trend has not changed significantly; a low is expected to deepen over the Maritimes and southern New England will be caught in the tightening pressure gradient as high pressure remains towards the Great Lakes. Gale-force winds are a possibility over the waters, and winds could possibly climb into storm force criteria. Those of us on land will also likely see elevated winds that will only make it feel even colder. Temperatures aloft sink to around -25C at 925 mb Saturday night, which when combined with the winds, it could end up feeling like -30F in parts of the Berkshires and between -20F and -10F elsewhere. Ensemble guidance continues to center the higher probabilities for wind chills below -25F over the Berkshires and the higher elevations of central MA. NAEFS guidance also indicates low level temperatures reaching 2 to 3 standard deviations below normal. Bottom line, it will very likely be dangerously cold and windy this weekend, especially heading into Sunday morning.

With the elevated winds and very cold temperatures, confidence is increasing in the chance for heavy freezing spray over the waters this weekend.

AVIATION /18Z TUESDAY THROUGH SUNDAY/

Forecaster Confidence Levels...

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

18Z TAF Update...High confidence.

Rest of today and tonight...High Confidence.

VFR. Light westerly winds becoming light and variable overnight.

Tomorrow...High Confidence.

VFR. Sustained winds increase to 10 knots out of the northwest by late morning/early afternoon.

Tomorrow Night...High Confidence.

VFR. Light northwest winds.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High Confidence in TAF.

Outlook /Thursday through Saturday/...

Wednesday Night through Friday: VFR.

Friday Night: Mainly VFR, with local IFR possible. Breezy. Chance SN.

Saturday: Mainly VFR, with local IFR possible. Strong winds with local gusts up to 40 kt. Chance SN.

MARINE

Forecaster Confidence Levels...

Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.

Through Wednesday night...High confidence.

Quiet weather across the coastal waters by early February standards through Thursday. Significant wave heights generally 1-2 feet. Light winds tonight increase out of the northeast tomororrow to around 15 knots. Some gusts to 20 knots possible at times.

Outlook /Thursday through Saturday/...

Wednesday Night through Friday: Winds less than 25 kt.

Friday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Snow likely. Local visibility 1 to 3 nm.

Saturday: gale force winds with areas of gusts up to 45 kt. Rough seas up to 14 ft. Freezing spray, snow likely. Local visibility 1 nm or less.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...None.