textproduct: Boston / Norton

SYNOPSIS

Approaching low pressure allows mainly rain to overspread the region from west to east during the afternoon/early evening hours with any snow confined to the highest terrain of the Berkshires and northern Worcester Hills. A cold front crosses the region later tonight...bringing mainly dry but windy and much colder weather Thursday into Thursday night. Wind Chills will be dropping to between 0 and 10 above Thursday night. It will still be blustery and chilly Friday with winds finally diminishing Saturday...but temperatures still remaining a bit below normal. The risk for a period of snow has decreased some Saturday night into Sunday...but this is not set in stone. Another shot of arctic air with well below normal temperatures will follow later Sunday into early next week.

NEAR TERM /UNTIL 6 PM THIS EVENING/

Key Messages:

* Rain overspreads the region from west to east this afternoon perhaps not reaching I-95 until this evening

* Any snow this afternoon and evening will be confined to the highest terrain of the Berks/Worcester Hills

Today...

Warm advection and gusty southerly winds bring 850mb temps above 0C across much of the region this afternoon. Expecting mild surface temperatures in the 40s to perhaps near 50 across southeastern MA and RI today. Areas across western/north central MA will be chillier with highs mainly in the 30s. Rain should overspread the region this afternoon into this evening from west to east. It may not even reach the I-95 corridor until this evening. Mainly expecting rain with any snow confined the higher elevations of The Berkshires and northern Worcester Hills. Accumulations will be minor, but may approach 1-2 inches on the east slopes of The Berks.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/

Key Messages...

* Lingering rain /highest terrain snow/ winds down later this evening with drier but blustery weather following overnight

* Quite windy and cold Thursday with steady or slowly falling temperatures into the 20s and lower 30s by mid-late afternoon

Tonight...

A cold front crosses the region later tonight bringing and end to the rain /very high terrain snow/ this evening. This will be followed by a brisk west/northwest wind and temperatures dipping back down into the upper 20s/low 30s by Thursday morning.

Thursday...

Cold day ahead for Thursday behind the cold front. Guidance shows strong cold air advection with 850mb temps falling near -15C by the evening. Thursday's high temperatures will occur around midnight before the column quickly cools and temps fall back below freezing Thursday morning. For most of us, daytime temperatures will struggle to warm by even a couple of degrees, and they may even cool throughout the day in the higher terrain.

Bigger weather story Thursday will be increasing winds behind a deepening area of low pressure over southern Quebec. BUFKIT soundings show a deepening mixed layer throughout the day with a LLJ strengthening to 45-55 kts at the top of the mixed layer. Mid and low-level winds of this magnitude will translate to gusts between 35 and 45 mph for most locations with the chance for occasional gusts up to 50 mph in the higher terrain. Future forecast updates may include an upgrade to a wind advisory for much of the region if the low level jet trends stronger in guidance. Biggest impact from the winds will be wind chills falling from the teens to the 20s early in the afternoon to as low as the single digits above zero in the terrain to the mid/upper teens above zero for the remainder of Southern New England, including the Cape and Islands. Finally, high res guidance is showing the chance for isolated snow showers and flurries associated with lake effect snow streamers Thursday afternoon. The best chance for this activity would likely be in the Berkshires and perhaps into central Mass.

LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/

Key Messages...

* Quite Windy & cold Thu night...Wind Chills between 0 and 10 above * Dry, but blustery and cold Fri...Highs upper 20s to the middle 30s * Mainly dry during the day Sat with highs generally in the 30s * Snow risk has decreased some Sat night-Sun...but not set in stone * Another shot of arctic air late Sun-Mon...Highs Mon only in the 20s Details...

Thursday night...

It will remain quite windy Thu night given a strong WNW 850 mb jet on the order of 50-60 knots. This coupled with 850T near -15C will yield excellent mixing. We expect northwest wind gusts of 35-50 mph and may need Wind Headlines well into the overnight hours. The strong winds will keep temps from completely bottoming out...but the CAA will result in lows still in the teens with downtown Boston/Providence and Cape in the 20-25 degree range. More importantly the strong winds will result in Wind Chills dropping to between 0 and 10 above and even briefly below zero in the highest terrain!

Dry weather will generally prevail Thu night...but given cold strong westerly flow some remnant Lake effect moisture may result in a brief spot snow shower/flurry or two.

Friday...

Strong low pressure shifts north of the Canadian Maritimes on Friday. Still enough of a pressure gradient though to result in blustery conditions. While winds will not be a strong as what we are expecting tomorrow...still expect westerly wind gusts of 25 to 35 mph. Highs on Friday will remain cold...generally in the upper 20s across the high terrain to the lower-middle 30s elsewhere.

This Weekend...

A ridge of high pressure to our south will slowly move east on Saturday. At the same time...another piece of strong shortwave energy will be dropping southeastward into the Great Lakes. The 00z models indicate the trough axis further east than guidance over the past 12-24 hours. This tends to suppress the low pressure further south in much of the guidance compared to yesterday/s runs. So the overall snow threat in the Sat night to Sun has decreased...but this is not set in stone. There are still individual ensemble members especially from the CMC guidance that track the low pressure system further north. The models seem to be struggling with amplitude/timing of northern stream energy which will have a significant impact on the track of this wave of low pressure. So while odds for accumulating snow have decreased some Sat night- Sun...still too early to rule out a trend back north. Will need another 36-48 hours to have more confidence in the eventual outcome.

High temps will mainly be in the 30s this weekend with the colder day on Sunday. In fact...temperatures may be falling during the day Sunday with a gusty NW developing behind the next arctic cold front.

Monday and Tuesday...

Another short of arctic air impacts the region for the start of the next work week. While mainly dry weather is expected...high temps will be well below normal. Highs on Monday will likely only be in the 20s. May see a bit of a modification by Tuesday...but still expect highs only in the upper 20s to the middle 30s.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/

Forecaster Confidence Levels...

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

12z TAF Update...

Today and tonight...Moderate confidence.

Mainly VFR conditions this morning. An area of mainly rain will gradually overspread interior southern New England this afternoon...gradually lowering conditions to MVFR levels. This rain and lower cigs/vsbys may not reach the I-95 corridor until early this evening. Ptype mainly rain with any wet snow confined to the highest terrain of the Berks and northern Worcester Hills. SW winds should gust between 20 and 30 knots today...strongest near the coast where a few gusts up to 35 knots near the Cape and Islands will be possible.

MVFR conditions may dominate much of tonight with perhaps some localized IFR cigs/vsbys. The threat for rain should should come to en end after midnight as a cold front crosses the region. Conditions should improve to mainly VFR levels by 12z Thursday. SW wind gust of 15 to 25 knots will shift to the W by 12z Thursday with gusts increasing into the 20 to 30 knot range.

Thursday...High Confidence.

VFR conditions outside a brief localized spot snow shower or two. Westerly wind gusts of 30-40 knots with a few spots perhaps gusting near 45 knots.

KBOS Terminal...Moderate confidence in TAF.

KBDL Terminal...Moderate confidence in TAF.

Outlook /Thursday Night through Sunday/...

Thursday Night: VFR. Strong winds with gusts up to 45 kt. Slight chance SHSN.

Friday: VFR. Strong winds with local gusts up to 40 kt.

Friday Night: VFR. Windy with local gusts up to 30 kt.

Saturday: VFR. Breezy.

Saturday Night: VFR. Breezy. Slight chance SN.

Sunday: VFR. Windy with local gusts up to 30 kt. Chance SN.

MARINE

Forecaster Confidence Levels...

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

Today through Thursday ...High confidence.

Gale warning today for strong southwest LLJ ahead of cold front. SW wind gusts up to 35 knots. Cold front crosses the region later tonight followed by excellent mixing in the CAA Thu. Gale force wind gusts re-develop...but this time from a westerly direction. Gales posted for all waters.

Outlook /Thursday Night through Sunday/...

Thursday Night: Low risk for storm force winds with gusts up to 45 kt. Rough seas up to 11 ft.

Friday: Moderate risk for gale force winds with gusts up to 40 kt. Areas of rough seas.

Friday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas.

Saturday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Seas locally approaching 5 ft. Slight chance of rain showers.

Saturday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas. Chance of snow, slight chance of rain.

Sunday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas. Chance of snow, chance of rain.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Gale Warning from 7 AM Thursday to 1 PM EST Friday for ANZ230- 236. Gale Warning until 1 PM EST Friday for ANZ231>235-237-250-251- 254>256.