textproduct: Boston / Norton

WHAT HAS CHANGED

No major changes to the forecast.

KEY MESSAGES

- Mainly dry through Thursday Night with the exception of a few light snow showers this evening and overnight.

- Mostly dry through this weekend except a low chance for light nuisance snow Saturday. Temperatures make a return to near normal. Attention turns to late this weekend for a potential coastal storm, but forecast confidence remains low due to track uncertainty.

DISCUSSION

KEY MESSAGE 1...Mainly dry through Thursday Night with the exception of a few light snow showers this evening and overnight.

A mid level shortwave passes by southern New England late today into tonight. WHile this may be enough to trigger a few snow showers during this time, there is not much lift or humidity expected within the dendritic growth zone. Thus, really looking more like flurries over land. Over the coastal waters, could be a different story where some ocean effect processes can help to enhance the shower risk, which would be mainly a cold rain over the eastern MA coastal waters this evening.

Colder air moves over our region late tonight, so expecting low temperatures to be 5-7 degrees lower than what we saw this morning. This trend looks to continue through Thursday night.

KEY MESSAGE 2...Mostly dry through this weekend except a low chance for light nuisance snow Saturday. Temperatures make a return to near normal. Attention turns to late this weekend for a potential coastal storm, but forecast confidence remains low due to track uncertainty.

High pressure builds in over the Midwest/Mid-Atlantic regions later this week, finally pushing the arctic airmass offshore, bringing southern New England back to seasonable temperatures. High temperatures rise into the mid to upper 30s, though overnight lows will still fall into the teens and low 20s, with some spots in the interior in the single digits.

Another upper-level low moves through Friday night, bringing chances for another quick shot of snow showers to southern New England early Saturday morning. The latest NBM guidance indicates probabilities 20- 30% chance of seeing 0.1" of snow across eastern MA as PWATs remain only about 75% of normal. Heading into next week, guidance continues to indicate potential impacts from another storm moving across Texas and off the southeast Atlantic coast. Uncertainty in the timing and track only increases exponentially at that point, with the latest ensemble suite slowing the development of the low and increasing the spread of possible tracks. The Canadian ensemble indicates the closest track, passing just south of Nantucket, while the ECMWF ensemble shows the low passing south of the 40N/70W benchmark. The GFS ensemble struggles to resolve the low, with several members indicating the low may not remain organized as it moves offshore. Continued with low-end PoPs for Sunday night into Monday given the high amount of uncertainty at this point.

AVIATION /19Z WEDNESDAY THROUGH MONDAY/

Forecaster Confidence Levels...

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

Through 00Z...High confidence.

VFR CIGS with gusty NW winds up to around 25 kt. Can't rule out the low risk for an isolated flurry/light snow shower late this afternoon into this evening, mainly across western MA/CT. But could also be across portions of NE MA.

Tonight...High confidence.

VFR. Breezy NW winds with gusts up to 20 kt.

Thursday...High confidence.

VFR. Breezy NW winds with gusts 20-25 kts. Few snow showers possible over outer Cape Cod in the morning, but should be mainly over the waters to the E.

Thursday Night...High confidence.

VFR. Gusty NW winds up to 20 kt.

KBOS Terminal...High Confidence.

Low risk for a snow shower during the evening push. Hinted at this with a P6SM -SHSN, but the greater risk will be over the waters east of the terminal. Not anticipating much snow accumulation.

KBDL Terminal...High Confidence.

Outlook /Friday through Monday/...

Friday through Friday Night: VFR.

Saturday: VFR. Breezy.

Saturday Night through Sunday: VFR.

Sunday Night: VFR. Slight chance SN.

Washingtons Birthday: VFR. Breezy. Chance RA and SN.

MARINE

Forecaster Confidence Levels...

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

Through Thursday Night...High Confidence.

Low pressure south of the Maritimes will swing an inverted trough over the coastal waters tonight. This could trigger scattered rain showers, at least until colder air arrives after midnight, when snow showers would be favored over the eastern coastal waters. Gusty NW winds persist as well. Toward daybreak areas of freezing spray are likely, especially the nearshore waters of MA and RI.

Outlook /Friday through Monday/...

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

Sunday: Winds less than 25 kt.

Sunday Night: Winds less than 25 kt. Slight chance of rain, slight chance of snow.

Washingtons Birthday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 10 PM this evening to 10 AM EST Thursday for ANZ235-237. Small Craft Advisory from 6 PM this evening to 7 AM EST Friday for ANZ250. Small Craft Advisory until 7 AM EST Friday for ANZ254-255. Small Craft Advisory until 7 PM EST Thursday for ANZ256.