textproduct: Boston / Norton

WHAT HAS CHANGED

No major changes to the forecast.

KEY MESSAGES

- Mainly dry today with the exception of a few light snow showers for the outer Cape, potentially brushing Cape Ann and Nantucket this morning.

- Moisture-starved system could bring scattered snow showers late Friday night into early Saturday morning.

- Attention turns to a potential coastal storm for late Sunday night into Monday, but forecast confidence remains low due track uncertainty.

- Return of seasonable temperatures next week.

DISCUSSION

KEY MESSAGE 1...Mainly dry today with the exception of a few light snow showers for the outer Cape, potentially brushing Cape Ann and Nantucket this morning.

An inverted trough tied to a departed surface low shifts south across the southern New England coastal waters this morning. This will bring enough forcing for lift to support a period of snow showers. Widespread showers are not expected as the better forcing will be offshore; however, this will favor a brush along outer Cape Cod with potentially a quick brush across Cape Ann and perhaps Nantucket. Model soundings show weak lift and limited moisture in the dendritic growth zone equating more to light snow/flurries within these showers. Any accumulation will be light with HREF means barely showing any accumulation amongst higher-res guidance. Trace to a few tenths is more likely.

A modest pressure gradient stays intact today support NW winds with gusts around 20 mph. Cooler temperatures aloft will keep highs a few degrees cooler from Wednesday with highs in the low to mid 30s.

Quiet day Friday with high pressure subtly building in from the southwest. This will keep conditions dry during the day with near- seasonable temperatures. Winds trend lighter than the last few days as the pressure gradient relaxes more.

KEY MESSAGE 2...Moisture-starved system could bring scattered snow showers late Friday night into early Saturday morning.

Upper-level low and northern-stream shortwave crosses New England late Friday night into Saturday morning, brings a low (<30%) probability of scattered snow showers. This is a moisture-starved system with PWATs below climatological norms, QPF is limited to a few hundredths of an inch, minor accumulations of a tenth or two of snow remains possible. No impacts are anticipated. Otherwise dry conditions Saturday afternoon and Sunday. Both days brings highs in the mid-30s to 40 degrees. Nighttime lows Saturday night in the upper teens to low-20s, Sunday night a few degrees warmer in the low to mid-20s.

Key Message 3...Attention turns to a potential coastal storm for late Sunday night into Monday, but forecast confidence remains low due track uncertainty.

Looking ahead, guidance continues to signal for a robust mid-level shortwave to cross the Texas panhandle with development of an area of low pressure near the Red River Basin by Saturday afternoon. Where this feature moves toward is uncertain. The last few days have brought this surface low across the deep south and exiting near the coast of the Carolinas late Sunday night. Confidence in this system moving towards southern New England remains low. That being said, we cannot jump on to any given deterministic model run. It's a bit of model whiplash. It would be good to lean on ensemble guidance given the time frame. Guidance shows a northern-stream shortwave ejecting out of the Great Lakes region with subtle mid-level troughing Sunday night. Thinking this will keep the southern-stream energy offshore, which is being supported by the ensembles (GFS and Canadian). Cannot discredit the outlier, ECMWF ENS, southern and northern-stream energy phasing south of New England. A small number of the individual members bring the surface low very close to our region, which would mean greater impacts. Even with an out to sea path, there is potential for light snow with the passage of the northern- stream shortwave. Still, there is pounds of time to watch. For now, kept with lower-end PoPs for late Sunday night into Monday. Stay tuned!

Key Message 4...Return of seasonable temperatures next week.

Next week does feature warmer than typical temperatures for middle part of February, as highlighted by CPC's outlook between the 17th and the 21st. Signaling that temperatures are "likely above" what is the climatological norm. This doesn't mean excessive warmth, rather that the probability of the daily average temperature over the course of this period is leaning warmer than average. An early assessment, highs top out in the low to mid-40s with nighttime lows in the 20s.

AVIATION /12Z THURSDAY THROUGH MONDAY/

Forecaster Confidence Levels...

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

Today...High confidence.

VFR. Breezy NW winds with gusts 20-22 kts. Gusts become lighter and less consistent in the afternoon. Few snow showers possible over outer Cape Cod after 11Z.

Thursday Night...High confidence.

VFR. NW winds 6-11 kts. Few gusts 18-20 kts.

Friday...High confidence.

VFR. NW wind 8-12 kts.

KBOS Terminal...High Confidence.

KBDL Terminal...High Confidence.

Outlook /Friday Night through Monday/...

Friday Night through Saturday: Mainly VFR, with local IFR possible. Slight chance SHSN.

Saturday Night through Sunday: VFR.

Sunday Night: Mainly VFR, with areas IFR possible. Chance SN.

Washingtons Birthday: MVFR/IFR conditions possible. Chance RA, chance SN.

MARINE

Forecaster Confidence Levels...

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

Thursday through Friday...High Confidence.

Low pressure south of the Maritimes will swing an inverted trough over the coastal waters early this morning, could trigger scattered snow showers. Toward daybreak areas of freezing spray are likely, especially the nearshore waters of MA and RI. Marginal small craft conditions continues through tonight, mainly for the outer waters. These conditions will lead to potential freezing spray again Friday morning. Seas and winds fall below advisory criteria before daybreak Friday.

Outlook /Friday Night through Monday/...

Friday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Local visibility 1 to 3 nm.

Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of snow showers. Areas of visibility 1 to 3 nm.

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. Chance of rain, chance of snow. Areas of visibility 1 to 3 nm.

Washingtons Birthday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain, chance of snow, patchy fog. Local visibility 1 to 3 nm.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 1 PM EST this afternoon for ANZ235- 237. Small Craft Advisory until 7 AM EST Friday for ANZ250-254-255. Small Craft Advisory until 10 PM EST this evening for ANZ256.