textproduct: Boston / Norton

SYNOPSIS

A weak wave of low pressure passes well to our south very late tonight into Saturday morning, which will bring a brief round of showers mainly across parts of Connecticut, Rhode Island and southeast Massachusetts. Otherwise, dry and seasonably cool weather is on tap for the weekend into Monday. Low pressure approaching from the west will likely bring a period of rain later Tuesday and/or Wednesday with drier weather favored by Thanksgiving.

NEAR TERM /THROUGH TONIGHT/

Key Messages...

* Rather cloudy tonight with lows in the 30s to the lower 40s * Some showers approach near daybreak...mainly across CT/RI/SE MA

Details...

Tonight...

High pressure off the mid-Atlantic coast will result in continued warm advection tonight...resulting in rather cloudy skies. Shortwave energy over the southern Great Lakes will move east across the mid- Atlantic states tonight. Strong upper level energy over Quebec will keep the mid level flow zonal and limit the northern extent of the rain shield with this wave of low pressure. We do think some showers will arrive near daybreak mainly across CT/RI/MA and especially near the south coast. Some of the guidance takes a few showers as far north as I-90...but if this occurs any showers will be light/short-lived. Low temps should bottom out in the 30s to the lower 40s.

SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/

Key Messages...

* Lingering showers mainly across CT/RI/SE MA early Sat ends by lunchtime...followed by partial clearing & highs mainly upper 40s

* Clear & cold Sat night with lows mainly in the 20s

Details...

Saturday...

The northern edge of the showers mainly impacts portions of CT/RI/SE MA Sat morning...but a few showers may briefly reach near I-90. These showers will not last long and should exit the region by lunchtime with any rainfall amounts rather light. This will be followed by partial clearing Sat afternoon from northwest to southeast. This partial clearing may not come in time for much sunshine though towards the Cape and Islands with the early sunset this time of year. High temps on Sat will mainly be in the upper 40s with a few spots reaching near 50.

Saturday night...

A ridge of high pressure builds into the region from the west Saturday night. This will result in mainly clear skies...light/calm winds and an excellent night of radiational cooling. Low temps should bottom out mainly in the 20s with some of the normally coldest spots perhaps dipping into the upper teens. The urban heat island of Boston will be the mild spot with low temps bottom out in the lower 30s.

LONG TERM /SUNDAY THROUGH THURSDAY/

Key Messages:

* Mostly dry and sunny through the weekend, but returning to unsettled conditions by mid-week.

Mostly dry and sunny for the remainder of the weekend as high pressure builds and moves across southern New England. Afternoon high temperatures expected in the mid to upper 40s (except mid to upper 30s for higher terrain areas).

Next chance for rain showers comes mid-week as another low pressure system passes through the James Bay and a high pressure moves offshore. Model guidance remains uncertain... the ECMWF is indicating a single round of showers pushing through Wednesday, but the GFS and Canadian are showing a secondary round of showers moving through Thursday morning. Regardless of differences in timing, there appears to be quite a lot of consensus as to PWAT values ranging from 0.8" in the northwest to 1.2" across the Cape and Islands. Still expecting precip to remain as rain showers at this time as surface temps remain above freezing, likely in the mid to upper 40s Tuesday and Wednesday afternoons.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

Forecaster Confidence Levels...

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

18z TAF Update...

This afternoon into tonight...High confidence.

Lingering areas of patchy MVFR ceilings should improve to mainly VFR levels by late afternoon. VFR conditions should persist tonight...but we may see some marginal MVFR cigs/vsbys develop near daybreak towards the south coast on the northern edge of some showers. Light SW winds.

Saturday...High confidence.

Some marginal MVFR conditions possible Saturday morning mainly across CT/RI/SE MA on the northern edge of a shield of showers. The best chance of these conditions are towards the south coast and any of this activity should depart by lunchtime. Otherwise...VFR conditions with winds becoming NW at 5-10 knots.

Saturday night...High confidence.

VFR. Calm/light NW winds.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Sunday through Tuesday/...

Saturday Night: VFR. Breezy.

Sunday: VFR.

Sunday Night through Monday: VFR. Breezy.

Monday Night: VFR.

Tuesday: VFR. Chance RA.

MARINE

Forecaster Confidence Levels...

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

Tonight through Saturday night...High confidence.

Low pressure will pass well south of the waters later tonight into Sat morning. This will be followed by a ridge of high pressure building in from the west Sat night. We probably will see a period of NW wind gusts of 20 to 25 knots late Sat/Sat evening in the cold air advection pattern. While this may briefly reach marginal small craft advisory thresholds...overall expect conditions to remain below criteria through Sat night.

Outlook /Sunday through Tuesday/...

Saturday Night: Winds less than 25 kt. Areas of seas approaching 5 ft.

Sunday: Winds less than 25 kt.

Sunday Night through Monday: Winds less than 25 kt. Seas locally approaching 5 ft.

Monday Night: Winds less than 25 kt.

Tuesday: Winds less than 25 kt. Chance of rain.

BOX WATCHES/WARNINGS/ADVISORIES

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