textproduct: Boston / Norton

WHAT HAS CHANGED

There is a low risk for severe weather Friday between 5 and 11 pm in the form of strong to localized damaging wind gusts.

KEY MESSAGES

- Brief period of showers mainly Fri morning with a lull in the activity much of Fri afternoon outside of a few spot showers. Cluster of showers & perhaps a few embedded t-storms with even a low risk for severe weather between 5 and 11 pm Fri evening. Windy and much cooler Sat with highs in the lower-middle 50s.

- Chilly night Saturday night with below-freezing low temperatures away from the coasts.

- Dry with a modest warmup through early next week, though monitoring coastal storminess near or south of the mid- Atlantic waters.

DISCUSSION

KEY MESSAGE 1...Brief period of showers mainly Fri morning with a lull in the activity much of Fri afternoon outside of a few spot showers. Cluster of showers & perhaps a few embedded t-storms with even a low risk for severe weather between 5 and 11 pm Fri evening. Windy and much cooler Sat with highs in the lower-middle 50s.

Large high pressure shifts east of the region tonight as an intensifying low pressure moves across the eastern Great Lakes. This will allow a return southerly flow of air along with increasing low level moisture to work northward into the region overnight. Initially...mainly clear skies/light winds will allow for temps to fall quickly through the 40s in many locations shortly after sunset this evening. However...increasing clouds along with developing low level southeast flow will allow for slowly rising temperatures toward daybreak.

In addition...the developing southerly LLJ/moisture transport will increase the forcing for ascent and allow for a cluster of showers to develop toward daybreak across interior southern New England. These showers may reach the coastal plain during the early-mid morning hours. The showers should be fairly numerous especially across northern MA...but the steady showers should be relatively short-lived lasting generally 1-3 hours in a given location. Otherwise...a good portion of Fri afternoon should feature a lull in the activity. A few spot showers certainly will remain possible...But much of this period may feature just cloudy skies with a breezy southerly wind. Despite lots of clouds...strong warm advection should push highs well into the 60s in many locations perhaps even near 70 in few spots. Dewpoints reaching or breaking 60+ will result in a bit of humidity too for the middle of October standards.

The main concern though is between 5 and 11 pm Fri evening as a cold front crosses the region. There should be roughly a few hundred J/KG of at least elevated Cape ahead of this front. Strong jet dynamics/forcing are also depicted ahead of this front with 55-65 knots of effective shear. The high resolution models generally show a line of showers with perhaps some embedded thunder as the cold front sweeps across the region. Despite very strong jet dynamics...instability is meager...so the severe weather potential is low but brief sub-severe wind gusts of 35-50 mph are still possible even if the showers do not contain any thunder. However...if we end up getting just a bit better moisture return off the relatively warm ocean...the low risk for severe weather could be realized. The CSU machine learning probabilities as well as the NCAR HRRR neural network indicate a low risk for severe weather. Again this is a low probability...but it needs to be watched. The main risk would be locally strong to damaging wind gusts especially with fully leafed trees across most locations.

Otherwise...a much cooler airmass works into the region late Fri night and Saturday on quite gusty NW winds. A few lingering showers possible into mid-morning Sat near the southeast New England coast. Otherwise...windy with northwest wind gusts on the order of 25 to 35 mph with a few gusts near 40 mph expected on Sat. Despite skies becoming partly sunny on Sat...highs will be held in the lower to middle 50s.

KEY MESSAGE 2...Chilly night Saturday night with below-freezing low temperatures away from the coasts.

After a cool, dry and blustery Saturday, looking at one of the coldest nights we've seen to this point in autumn 2026 as broad, and strong high pressure settles in over the Northeast. It's still a little unclear how quickly the blustery NW winds from the daytime hours subside but at least very good radiational cooling conditions are anticipated. With a likely cool start, should see lows drop into mid 20s to low 30s range for much of Southern New England except in the mid 30s for the cities and Cape Cod/Islands. Note that the frost/freeze program for Southern New England has ended as of October 11th and not expected to resume again until mid-Spring 2027, which means freeze/frost headlines won't be issued; however if you still have plants/crops outside, you'll want to take the necessary precautions to prevent freeze/frost damage.

KEY MESSAGE 3...Dry with a modest warmup through early next week, though monitoring coastal storminess near or south of the mid- Atlantic waters.

The expansive surface high pressure from Saturday night, spanning from the Southern Appalachians through Southern New England and the Canadian Maritimes, then governs our weather pattern Sunday through early next week. This will facilitate a steady warming trend with slightly above normal temperatures, with mostly clear skies and strong diurnal temperature ranges (milder days, cool nights). Looking at highs Sunday in the mid to upper 50s and lows in the 30s. Highs by early next week rebound back into the middle 60s with lows in the upper 30s/low 40s.

It should be a largely dry period through Tuesday, though the one system we'll be monitoring is a closed upper low near the mid- Atlantic/Carolinas waters, a feature which became detached from the broader upper level westerlies along the stalled frontal boundary from Friday night and early Saturday. The general position of this system is generally agreed upon across the ensemble NWP suite and AI- based guidance, but there's quite a bit of uncertainty on if we see any of this moisture come back northward through the governing ridge. That could bring at least enhanced NE breezes, strongest near Cape Cod, and possibly some clouds/light rain showers by Tuesday for southeast New England. But it's very possible it ends up being mainly dry/remains to our south. Will maintain blended guidance for the time being until there's more agreement, but for now will continue to reassess subsequent guidance.

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:

Today and Tonight...High confidence.

VFR. Winds currently shifting NE and diminishing to near 10 kts as the high pressure system takes over. Winds shift SE this evening, generally around 5 kts, and some higher level clouds begin to build in overnight.

Thursday Night...Moderate confidence.

Becoming MVFR to IFR with -SHRA moving in from west to east between 06Z and 12Z. S-SW winds develop with gusts nearing 20 kt closer to sunrise.

Friday...Moderate confidence.

IFR to LIFR with SHRA. Brief respite from SHRA possible in the afternoon hours, though low ceilings continue. Will need to monitor for the risk of some embedded TSRA and convective features. Gusty S to SW winds up to 30 kt with higher gusts possible near the coasts and higher elevations.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Saturday through Tuesday/...

Saturday: Mainly VFR, with local MVFR possible. Windy with gusts up to 30 kt.

Saturday Night: VFR. Windy with local gusts up to 30 kt. Patchy frost.

Sunday through Sunday Night: VFR.

Monday: VFR. Breezy.

Monday Night through Tuesday: VFR.

MARINE

Forecaster Confidence Levels...

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

Tonight through Saturday...High confidence.

High pressure moves east of the waters tonight...but winds/seas will remain below small craft advisory thresholds. Intensifying low pressure will move across the eastern Great Lakes tonight and then proceed near the northern New England/Quebec border Fri into Fri evening. Ahead of this front...strong small craft southerly wind gusts along with choppy seas will develop early Fri. We have hoisted small craft headlines for all our waters on Fri.

Behind this cold front...NW wind gusts of 30-35 knots will develop especially late Fri night into Sat in the CAA pattern. Given it is marginal...we opted to continue Gale Watch over this time period. Despite marginal conditions...cold air advection patterns can often overperform this time of year given relatively warm SST which can enhance mixing. Either way...strong SCA to gale force wind gusts are expected with choppy seas.

Outlook /Saturday night through Tuesday/...

Saturday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 10 ft.

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

Sunday Night: Winds less than 25 kt.

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

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

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 8 AM to 6 PM EDT Friday for ANZ230- 236. Gale Watch from Friday evening through Saturday evening for ANZ230>237-250-251-254>256-280>283. Small Craft Advisory from 6 AM to 6 PM EDT Friday for ANZ231>235-237-250-251-254>256.