textproduct: Boston / Norton

WHAT HAS CHANGED

Cancelled the River Flood Warning along the Pawtuxet River at Cranston, as river levels are slowly receding below flood stage. Otherwise, no other significant changes were made.

KEY MESSAGES

- Quiet weather prevails today and Thursday with slowly moderating temperatures and mostly clear to partly cloudy conditions.

- Unsettled weather for the weekend into early next week with periodic chances for showers.

DISCUSSION

KEY MESSAGE 1...Quiet weather prevails today and Thursday with slowly moderating temperatures and mostly clear to partly cloudy conditions.

Overall quiescent weather expected today and into Thursday as well. Broad area of high pressure over the central Appalachians progresses northward through Southern New England and into the Canadian Maritimes by tonight, then remaining in place into most of Thursday too. Our airmass remains unseasonably cold by mid- March standards, although gradually modifying each day...with 925 mb temps warming to around -6 to -8C today and continuing to warm to around -1 to -3C. Dry weather prevails, with mostly sunny to partly cloudy conditions as a stream of midlevel clouds moves in. We'll start off Thursday with mostly clear skies as well, but with increasing clouds west to east. The other commonality to both Wednesday and Thursday is the potential for weak onshore flow or local seabreezes to develop given the weak pressure gradient and high pressure parked to our south and east. Highs today should top out in the mid to upper 30s, about 10 degrees below normal, but ends up closer to the mid 40s for Thursday. Still below normal, but less so.

Cloud cover then starts to increase into the afternoon as a weak, Clipper system passes to our north late Thursday night into early Friday morning. Deep moisture is lacking with this Clipper system and model soundings support the idea that what moisture there is looks to be more from cloud cover than measurable precipitation. Overall a mostly cloudy Thursday night but generally dry.

KEY MESSAGE 2...Unsettled weather for the weekend into early next week with periodic chances for showers.

Conditions will be mainly dry for the remainder of Friday with further warming in temperatures. Highs likely rise in the upper 40s and low 50s.

The weather pattern leans unsettled into the weekend as a result of a series of shortwave troughs moving through the flow aloft bringing periodic chance for showers. First shot at showers is overnight Friday into early Saturday. Timing of the waves becomes lower confidence after that, but there may be another round of showers possible Saturday night. Shower coverage will be more scattered given limited forcing and moisture. Higher moisture pushes in Sunday ahead of an approaching system which may support more widespread showers Sunday night into Monday.

Temperatures more likely range around to slightly above normal Saturday in the upper 40s/low 50s. Some guidance hints at warmer highs given warmer temperatuers aloft, however cloud cover might limit heating. Sunday trends a little warmer overall with highs solidly in the 50s for most.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/

Forecaster Confidence Levels...

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

06z TAF Update:

Through 12z Wednesday: High confidence.

VFR. Still gusty especially eastern terminals with gusts to 25 kt; gusts easing around 08-10z, giving way to sustained NW winds around 5-10 kt.

Today: High confidence, though moderate on possible late-day seabreeze.

VFR with some mid-level clouds in the aftn. Light NW winds trending to southerly 5-10 kt. Potential seabreeze as soon as 19z at BOS, which would maintain itself thru 00z were it to develop.

Tonight into Thursday: High confidence.

VFR, though low to midlevel cloud cover increases later in the day Thursday. Winds become SE 5-10 kt tonight and continuing into Thursday.

KBOS Terminal...High confidence in TAF. Potential seabreeze as soon as 19z Wed; likely to continue until 00z Thurs were it to develop.

KBDL Terminal...High confidence in TAF.

Outlook /Thursday Night through Sunday/...

Thursday Night through Friday: VFR.

Friday Night: Mainly VFR, with local MVFR possible. Chance RA.

Saturday: Mainly VFR, with areas MVFR possible. Breezy. Chance RA.

Saturday Night: Mainly VFR, with local MVFR possible. Breezy. Slight chance RA.

Sunday: Mainly VFR, with local MVFR possible. Breezy. Chance RA.

MARINE

Forecaster Confidence Levels...

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

SCAs continue on most waters due to westerly wind gusts 25-30 kt and rough seas around 7-10 ft. The gusts will be easing by the pre-dawn hours to WNW winds around 10-20 kt today, with speeds continuing to ease into the afternoon. Thus SCAs should be coming down by early this morning at least over the nearshore waters. Seas will take a longer time to fall below 5 ft over the outer waters and probably will not do so until late tonight or early Thursday morning, with SCAs over the outer waters running thru 7 AM Thursday.

Conditions then remain below SCA criterion through Thursday, with SE winds around 10-15 kt and seas under 4 ft all waters.

Outlook /Thursday Night through Sunday/...

Thursday Night through Friday: Winds less than 25 kt. Seas locally approaching 5 ft.

Friday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain.

Saturday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain.

Saturday Night: Winds less than 25 kt. Seas up to 5 ft. Slight chance of rain.

Sunday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 8 AM EDT this morning for ANZ231>234-251. Small Craft Advisory until 8 PM EDT this evening for ANZ235- 237. Small Craft Advisory until 8 AM EDT Thursday for ANZ250- 254>256.