textproduct: Boston / Norton

SYNOPSIS

After a frigid start early this morning...a ridge of high pressure will result in dry weather but high temperatures still well below normal today. A moisture starved shortwave crosses the region tonight with a period of mainly scattered light snow showers. A more significant disturbance brings much milder temperatures and a period of mainly rain Wednesday afternoon and evening with any snow confined to the highest terrain of the Berkshires and northern Worcester Hills. A cold front crosses the region later Wednesday night...bringing mainly dry, but blustery and cold weather returning Thursday into Friday. Low pressure may bring snow with even some ice/rain to the region Saturday night into Sunday depending on its track. This will be followed by another shot of arctic air and well below normal temperatures early next week.

NEAR TERM /UNTIL 6 PM THIS EVENING/

Key Messages...

* Dry & unseasonably cold today

Details...

Today...

A cold albeit quiet and dry day setting up for today. A clear cold start will give way to increasing mid and high level clouds as a weak mid-level disturbance begins to approach from the Great Lakes. Arctic high pressure moves offshore resulting in an increasing return flow and mid-level warming. Guidance shows 850mb temps increasing from -15C in the morning to -9C or so by the afternoon. Will be a cold day with temps rising from the single digits to the teens and lower 20s by the afternoon. Winds will become southerly then eventually southwesterly by the afternoon as WAA increases.

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

Key Messages...

* Brief scattered light snow showers tonight with any accumulations mainly a dusting to less than 1 inch

* Stronger disturbance arrives from the Great Lakes Wednesday afternoon w/ rain and accumulating elevation snow possible.

Tonight...

Increasing mid-level frontogenesis under an upper level impulse will bring a brief period of showery precipitation from west to east between 02-08z. Expecting negligible snow totals (dusting to an inch) across the interior as the precipitation will have to overcome a fairly deep layer of drier air. Rain showers more likely S of I-95 as temps warm near or above freezing. Overall a low impact event that will last for only a few hours. Still, there could be slick spots as partial clearing cools temps down a few degrees late Tuesday night.

Wednesday...

A stronger clipper disturbance approaches from the Great Lakes Wednesday. Much of Wednesday morning should be dry, but a period of widespread rain should overspread the region from west to east. Rapidly warming boundary layer on gusty southwest winds should result in Ptype generally in the from of rain. The exception will be the highest terrain of the Berks and northern Worcester Hills...where some wet snow is expected. Temperatures may actually be somewhat mild SE of I-95 as highs approach 50. Expecting generally light QPF with the NBM advertising up to 0.5". Best chance for accumulating snow will be in the elevated terrain of the Berks and perhaps the northern Worcester Hills where event totals 1-3 inches are possible.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/

Key Messages...

* Lingering showers/highest terrain snow showers depart Wed evening

* Cold and windy Thu with continued cold weather Fri...Highs in the upper 20s/30s with dry weather outside a brief spot snow shower

* Low pressure may bring snow or even some ice/rain to the region Sat night into Sun depending on its track which remains uncertain

* Another shot of arctic air Mon into Tue with unseasonably cold highs in the 20s to the lower 30s and mainly dry weather

Details...

Wednesday night...

Intensifying low pressure moves eastward along the northern New England and Quebec border Wednesday night...dragging a cold front across our region. Lingering rain showers with any snow showers confined to the highest terrain of the Berks/northern Worcester Hills will come to an end Wednesday evening. It will turn rather blustery behind this cold front later Wednesday night with increasing west winds. Overnight low temps should mainly be in the 25 to 35 degree range with the mildest of those readings near and southeast of the I-95 corridor.

Thursday...

Windy and colder weather returns to the region on Thursday. Strong cold advection will result in 850T dropping to between -13C/-14c. This should result in steady or slowly falling temperatures with afternoon temperatures mainly in the upper 20s to the middle 30s. Bufkit indicates excellent mixing which should yield westerly wind gusts of 25 to 40 mph. This will result in afternoon wind chill values mainly in the teens to the lower 20s.

Dry weather should generally prevail...but given cold westerly flow some remnant lake effect moisture may result in a brief spot snow shower/flurry or two.

Thursday night and Friday...

Strong low pressure just east of the Canadian Maritimes will continue to generate a blustery westerly flow of dry but cold air into southern New England. Lows Thu night will mainly be in the teens to the middle 20s with highs Fri in the upper 20s and middle 30s.

This Weekend...

The forecast becomes rather complex this weekend. Low pressure developing in the Tennessee Valley will be lifting northeast towards the mid-Atlantic states. At the same time...northern stream energy will be dropping another shot of arctic air into the Great Lakes. The timing and amplitude of this shortwave energy will determine the track of the low pressure system. FWIW the latest 00z guidance has trended north with this low pressure system...particularly some of the EPS/CMC ensembles. That being said...there was still significant spread though among many of the individual ensembles. While plenty of uncertainty remains...the trend was towards a greater risk for a period of snow Sat night into Sun. However...the potential for more northern solutions also introduces the risk for some ice/rain getting involved especially south of I-90. We will need a few more days to have a better idea on this potential...but certainly something to watch in the next few days.

Monday and Tuesday...

Regardless of what happens this weekend...it appears that another shot of arctic air with well below normal temperatures will move into the region early next week. Highs probably will only be in the 20s to the lower 30s and perhaps even colder than that if the latest 00z ECMWF verifies.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

Forecaster Confidence Levels...

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

12z TAF Update...

Today...High confidence.

VFR. Light and variable winds becoming SW at 5 to 10 knots this afternoon.

Tonight...High confidence.

Mainly VFR. However...a brief period of MVFR conditions possible in the 02z to 10z time frame from west to east in scattered light snow showers possibly mixing with or changing to rain showers near the south coast. SW winds 5 to 15 knots with some 20+ knots developing late in the Worcester Hills and near the coast.

Wednesday...Moderate confidence.

Mainly VFR conditions expected Wednesday morning. Mainly rain overspreads the region from west to east during the afternoon...lowing conditions in the the MVFR levels northwest of I-95 with even some localized IFR conditions across the interior. Ptype generally rain except some wet snow in the high terrain of the Berkshires and possibly the highest terrain of the northern Worcester Hills. SW wind gusts of 20 to 30 knots develop by afternoon with perhaps some 35 knot gusts near the south coast, Cape and Islands.

KBOS Terminal...High Confidence in TAF.

KBDL Terminal...High Confidence in TAF.

Outlook /Wednesday Night through Saturday/...

Wednesday Night: Mainly IFR, with local MVFR possible. Windy with gusts up to 35 kt. Chance SHRA, slight chance SHSN.

Thursday through Thursday Night: VFR. Windy with gusts up to 30 kt. Slight chance SHSN.

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

Friday Night: VFR. Breezy. Slight chance SHSN.

Saturday: VFR. Breezy. Chance SHRA, slight chance SHSN.

MARINE

Forecaster Confidence Levels...

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

Today through Wednesday...High confidence.

Winds shift to the southwest this afternoon as high pressure moves east of the region. Strong LLJ allows for SW wind gusts of 35 knots to develop late tonight with another round on Wednesday. Therefore...Gale Watches have been issued for all open waters late tonight into Wednesday. Long southwest fetch should allow seas to build to between 6 and 12 feet across our southern waters.

Outlook /Wednesday Night through Saturday/...

Wednesday Night: Low risk for gale force winds with gusts up to 35 kt. Areas of rough seas. Chance of rain showers. Areas of visibility 1 to 3 nm.

Thursday: Moderate risk for gale force winds with gusts up to 35 kt. Areas of rough seas. Local visibility 1 to 3 nm.

Thursday Night: Moderate risk for gale force winds with gusts up to 40 kt. Areas of rough seas. Slight chance of snow showers.

Friday: Moderate risk for gale force winds with gusts up to 35 kt. Local rough seas.

Friday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of seas approaching 5 ft. Slight chance of rain showers, slight chance of snow showers.

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

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 10 PM this evening to 7 PM EST Wednesday for ANZ230-236. Gale Watch from late tonight through Wednesday evening for ANZ231>235-237-250-251-254>256.