textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes were made to the forecast during this update.

KEY MESSAGES

- Mild and breezy conditions Friday ahead of an approaching frontal system. Periods of rain develop Friday night as the front pushes through but we're not expecting a washout at this time.

- Breezy and unsettled through early next week. Another round of showers Sunday night into Monday. Cooler, but still near normal, temperatures expected Monday through mid-week.

DISCUSSION

KEY MESSAGE 1...Mild and breezy conditions Friday ahead of an approaching frontal system. Periods of rain develop Friday night as the front pushes through but we're not expecting a washout at this time.

Fairly strong frontal wave dives SE from Ontario later Friday bringing a period of breezy and rainy conditions. Breezy weather will be driven by a robust south westerly low level jet that will strengthen to 45-55 knots by the evening. Otherwise, mostly sunny conditions should prevail at least during the morning hours Friday. Expect thickening mid and high level clouds Friday afternoon as well as an increasing southwest breeze. Wind speeds increase around 10-15 mph and gusts in the 25 to 35 mph range, with the higher end of that range more confined to Cape Cod and the Islands which typically gusts pretty well with SW flow (tempered by the cooler water temps). Should be a fairly mild day with highs in the lower 50s in most areas and perhaps as high as the upper 50s in the CT and Merrimack river valleys. Cooler with max temps in the upper 40s over the south coast, Cape and Islands due to persistent SW flow over the waters.

Increasing chance for POPs Friday evening and overnight as a broken band of rain and showers moves from NW to SE. This will also lead to decreasing SW wind gusts as the column stabilizes. As it does so, it will act on a modest PWAT plume increasing to around 0.75-0.8 inches, which is really not that impressive. Kept PoPs at high Likely to lower Categorical, although this doesn't look to be a significant precip-maker, with ensemble QPF probs still indicating low (< 30%) probs of rainfall totals greater than 0.50". The NBM has about a 50-50 chance of seeing greater than 0.20 inches of rain. Given stable thermodynamics and only modest PWATs to work with, the rainfall probs seem reasonable. May have to watch for a slowing frontal zone though, as the orientation of the front becomes nearly parallel to the 500 mb height contours, which could result in lingering showers into early Saturday morning.

KEY MESSAGE 2...Breezy and unsettled through early next week. Another round of showers Sunday night into Monday. Cooler, but still near normal, temperatures expected Monday through mid-week.

We will still be dealing with a pesky front late Sunday into Monday as it gets hung up by a low pressure moving over the Great Lakes. This low pressure is anticipated to move just south of New England late Sunday night into Monday, finally dragging this front away from our region.

While there is a chance for some rainfall Sunday afternoon, we're thinking the majority of precipitation will be Sunday night. It's then a race between the precipitation leaving and colder air trying to overspread southern New England. At this time, there does appear to be a brief window where light snow is possible late Sunday night into Monday morning. That said, this would be mainly for areas along and north of Route 2 in MA, but could also impact the east slopes of the Berkshires and Worcester Hills. Given the brief duration of any snow, little to no snow accumulation is expected.

High pressure over the central Appalachians Tuesday then takes over our weather for a brief time, before moving offshore from the Mid Atlantic coast Wednesday.

Still not certain about the impacts from another cold front some time late Wednesday into Wednesday night. This front looks to be moisture-starved, so thinking mainly clouds. The next chance for rainfall could be Thursday as a warm front tries to pass us by.

Above normal temperatures Sunday trend to below normal Monday and Tuesday. Looking like near normal temperatures should return for Wednesday and Thursday.

AVIATION /18Z THURSDAY THROUGH TUESDAY/

Forecaster Confidence Levels...

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

18z TAF Update:

Tonight: High confidence.

VFR, though with lower-end VFR/borderline MVFR at BDL. S to SW winds 5-10 kt.

Friday: High confidence.

VFR. SW winds increase to around 10-15 kt with gusts to around 25-30 kt. Potential for low level wind shear as well. Possible areas of MVFR after 21z with -SHRA arriving around 00z.

KBOS Terminal...High confidence in TAF overnight through Friday afternoon. Moderate confidence in the timing VCSH Friday afternoon and evening.

KBDL Terminal...High confidence in TAF.

Outlook /Friday through Tuesday/...

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

Friday Night: MVFR/IFR conditions possible. Windy with gusts up to 30 kt. Chance RA.

Saturday through Saturday Night: VFR.

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

Sunday Night: Mainly MVFR, with local IFR possible. Breezy. RA likely.

Monday: Mainly VFR, with local IFR possible. Breezy. Chance RA.

Monday Night: VFR. Breezy.

Tuesday: VFR.

MARINE

Forecaster Confidence Levels...

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

Winds and seas will remain below marine headline thresholds through tonight. SE winds today around 10-15 kt to shift to S and then SW tonight into early Friday. Seas 4 ft or less on all waters.

SCA issued for the outer waters from 00z Sat thru 00z Sun. SCA in effect from 00z-09z Sat for Buzzards, Nantucket, and Cape Cod Bays. While a few gale-force gusts are possible, shallow mixing depth over the cooler marine boundary layer likely results in gusts in the 25-30 kt range. Areas of rain and showers likely result in areas of reduced visibility.

Outlook /Friday through Tuesday/...

Friday: Low risk for Small Craft Advisory winds with local gusts up to 30 kt. Seas locally approaching 5 ft.

Friday Night: Moderate risk for Small Craft Advisory winds with local gusts up to 30 kt. Seas up to 5 ft. Chance of rain.

Saturday: Winds less than 25 kt. Seas up to 5 ft.

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

Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain.

Sunday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Rain likely.

Monday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Chance of rain.

Monday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas.

Tuesday: Winds less than 25 kt. Local rough seas.

BOX WATCHES/WARNINGS/ADVISORIES

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