textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast.

KEY MESSAGES

- Isolated showers and thunderstorms this afternoon. Drier conditions following today's cold front.

- Mainly dry with seasonable temperatures through the weekend.

- Rain and thunderstorm chances return for the first half of next week. Seasonable temperatures continue.

DISCUSSION

KEY MESSAGE 1...Isolated showers and thunderstorms this afternoon. Drier conditions following today's cold front.

Satellite shows continued clearing over southern New England today, which has aided in the development of scattered showers and thunderstorms. As of the time of writing, the cold front is passing through western MA and CT based on latest observations towards the Berkshires and in north central CT. Ahead of the front, showers and thunderstorms have popped up across central MA, with an earlier round having gone through northern MA. These will continue to push eastward and will likely maintain their growth given the enhanced SBCAPE, MLCAPE, clearer skies, and warmer surface temperatures in the 80s with dew points climbing into the low 70s/upper 60s. Strong to damaging wind gusts remain a possibility given DCAPE values between 1000-1100 J/kg. These showers and thunderstorms should exit the region early tonight, generally around 8-9 PM. Some may linger a bit longer near the Cape and Islands, though.

As the cold front moves through the region today and tonight, winds will shift more NW, and drier air will move in with cooler temperatures. High pressure starts to build in from the west Thursday while an upper level trough moves over the northeast. Highs Thursday will reach the low to mid 80s given 925 mb temperatures around 16-18z. With high pressure building in, winds will slacken and seabreezes will likely develop tomorrow. Mostly clear skies and light to calm winds Thursday night will lend to radiational cooling as well, leading to lows dropping into the 50s.

KEY MESSAGE 2...Mainly dry with seasonable temperatures through the weekend.

While the synoptic pattern will feature broad, weak troughing in the mid levels over the northeast, subsidence associated with a building surface high pressure center will keep things dry from Friday through at least Sunday. This, while said troughing pattern keeps seasonable temperatures around; 850 mb temps remain in the 11-13C range clear through early next week, which will lead to high temperatures in the upper 70s to low 80s each day. Behind today's cold front, dewpoints will drop into the 40s and low 50s through Sunday as well, making it feel less humid and more comfortable. Altogether this should be a fantastic stretch of weather for outdoor plans.

KEY MESSAGE 3...Rain and thunderstorm chances return for the first half of next week. Seasonable temperatures continue.

The pattern begins to break down around Monday with the mid level trough digging into the northeast with several disturbances rotating around the base of the trough inducing areas of surface low pressure which will stand the chance to bring us rain and thunderstorms as soon as Monday with the threat continuing much of next week. As mentioned previously, there is no big warm-up on the horizon.

AVIATION /06Z THURSDAY THROUGH MONDAY/

Forecaster Confidence Levels...

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

06Z Update...

Through 12Z...High Confidence.

VFR. Periods of IFR and patchy fog possible on the Cape and Islands through 10Z. Winds WNW/NW 5-10 kts.

Thursday(Today)...High confidence.

VFR. Winds WNW to NW for most terminals 5-10 kts. Sea breezes for the coastal areas developing 18-20Z as NW winds weaken. If winds end up a touch stronger this afternoon, BOS may not sea breeze. Kept sea breeze in BOS TAF for now since it appears to be the more likely scenario at this time. Winds may become more variable later in the afternoon and evening for the interior terminals. Sea breezes shift toward S/SSE 21-00Z becoming S/SSW after 00Z.

Tonight...High confidence.

VFR. Light to calm winds overnight out of the SW.

KBOS Terminal...Moderate confidence in TAF.

Lower confidence due to some uncertainty in if the sea breeze will come in this afternoon. If winds end up staying around 10 kts, it may be just strong enough to keep the sea breeze offshore. It still is more likely a sea breeze develops 18-20Z out of the ESE, so kept in TAF for now. It may need to be re- evaluated for the 12Z TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Friday through Monday/...

Friday through Sunday Night: VFR.

Monday: Mainly VFR, with local MVFR possible. Slight chance SHRA.

MARINE

Forecaster Confidence Levels...

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

Tonight through Thursday Night

Small Craft Advisories remain in effect for SW winds 10-20 kts with gusts 25-30 kts and 6-10 foot seas for the outer coastal waters and southern waters. Highest waves are expected over the south coastal waters. Isolated showers and thunderstorms possible early tonight.

A cold front crosses the waters tonight resulting in a wind shift to the NW. Winds and seas will slowly decrease overnight across the northern waters. Seas will be the slower to decrease, especially across the southern waters. High Surf Advisory remains in effect for exposed southern coastlines through Thursday given the elevated seas and the higher risk for rip currents on Thursday given receding seas and residual swell.

Seas recede to 4 ft Thursday night with light winds over the waters.

Outlook /Friday through Monday/...

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

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

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

Sunday Night through Monday: Winds less than 25 kt. Slight chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...High Surf Advisory until 8 PM EDT this evening for MAZ020>024. RI...High Surf Advisory until 8 PM EDT this evening for RIZ006>008. MARINE...Small Craft Advisory until 2 AM EDT early this morning for ANZ232>234-250. Small Craft Advisory until 2 PM EDT this afternoon for ANZ235- 237. Small Craft Advisory until 8 PM EDT this evening for ANZ254>256.