textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

- Dry today, though cooler with few clouds following a backdoor cold front.

- Unsettled tonight through Thursday, with several opportunities for showers and thunderstorms. Timing which days may have better storm chances is still lower confidence.

- Mix of clouds and sun with diurnally driven spot showers Friday into the early part of Labor Day weekend, but drier weather most of the time. Dry and seasonable Sunday and on the Monday holiday, with onshore breezes.

DISCUSSION

KEY MESSAGE 1...Dry today, though cooler with few clouds following a backdoor cold front.

A backdoor cold front is expected to make its way across southern New England early this morning, clearing skies and ushering in drier air. This front should be south of the coast by around 8 AM. Light N to NE winds develop behind this front, which will result in lower temperatures across eastern MA. Farther inland, temperatures should be similar or slightly higher than yesterday due to more sunshine.

KEY MESSAGE 2...Unsettled tonight through Thursday, with several opportunities for showers and thunderstorms. Timing which days may have better storm chances is still lower confidence.

High pressure should become parked over the Maritimes, which will provide resistance to pushing the lingering front out of our region until late this week. AS long as this front is nearby, there should be at least a risk for some showers, and perhaps a few thunderstorms. That said, not expecting it will be raining all week.

Right now the two periods that appear to have the best chance of showers and storms looks to be tonight into the first part of Tuesday, and again later Wednesday afternoon into part of Thursday. Tried to provide some timing in the forecast based on the latest CAMs. Uncertainty in the precise timing and location details is still rather low. So, focused more on broader trends rather than trying to pin it down to the hour. Currently thinking the driest portion of this week should be late Tuesday night into Wednesday morning.

The potential for thunderstorms to become strong to severe looks limited, but a slightly better chance exists later Wednesday into Thursday as a stronger shortwave aloft allows for at least some of the more unstable warm sector to work its way in. KEY MESSAGE 3...Mix of clouds and sun with diurnally driven spot showers Friday into the early part of Labor Day weekend, but drier weather most of the time. Dry and seasonable Sunday and on the Monday holiday, with onshore breezes.

Stalled frontal boundary finally moves offshore Thursday, although cyclonic flow aloft will keep our weather pattern somewhat unsettled with a mix of clouds and sun. Spot showers are possible Friday and Saturday afternoon but should be drier much of the time. Broad high pressure then works in from the north Sunday into Labor Day, leading to an onshore flow but with sunny and dry conditions.

AVIATION /12Z MONDAY THROUGH FRIDAY/

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. A backdoor cold front moves westward through southern New England early this morning. This will flip winds to NE to E around 5-10 kt, a little stronger for the eastern coastal terminals.

Tonight...High confidence in trends. Moderate confidence in timing.

MVFR developing, with pockets of IFR possible late, across the interior. Rain chances increase from W to E after 00z Tuesday. Some embedded -TSRA possible as well.

Tuesday...High confidence in trends. Moderate confidence in timing.

MVFR with local IFR in showers and possible thunderstorms. Less coverage of SHRA/TSRA more likely in the afternoon.

KBOS Terminal...High confidence.

KBDL Terminal...High confidence.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Mainly VFR, with local IFR possible. Chance SHRA.

Wednesday: Mainly VFR, with local IFR possible. Chance SHRA, slight chance TSRA.

Wednesday Night: MVFR/IFR conditions possible. SHRA, chance TSRA.

Thursday: Mainly VFR, with local IFR possible. Chance SHRA, chance TSRA.

Thursday Night through Friday: VFR. Slight chance SHRA.

MARINE

Forecaster Confidence Levels...

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

Through Tuesday...High confidence.

A backdoor front moves across the waters from N to S early this morning, shifting winds more NE initially, then more S heading into the evening hours. Light S winds over the waters tonight, along with more chances for showers and thunderstorms. Increasing S to SE winds Tuesday with more showers and thunderstorms likely.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers.

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

Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Rain showers likely, chance of thunderstorms.

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, chance of thunderstorms.

Thursday Night: Winds less than 25 kt. Chance of rain showers.

Friday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

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