textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes to the forecast into this afternoon.

KEY MESSAGES

- Low pressure brings rain and strong to damaging wind to portions of southern New England today.

- First half of next week dominated by cooler temperatures and off-and-on showers.

- High uncertainty regarding the end of next week, but could be dry and unseasonably warm or more damp with seasonable temperatures.

DISCUSSION

KEY MESSAGE 1...Low pressure brings rain and strong to damaging wind to portions of southern New England today.

Anomalously potent low pressure had finally moved southeast of Nantucket early this afternoon. Expecting winds to continue to diminish late this afternoon into this evening as this low moves farther out to sea. Expecting rainfall to also end from NW to SE, perhaps taking as long as 8 PM to clear the Cape and Nantucket.

Below normal temperatures tonight, trend much closer to normal with plenty of early sunshine. Increasing mid level clouds during the afternoon.

KEY MESSAGE 2...First half of next week dominated by cooler temperatures and off-and-on showers.

Synoptic guidance hasn't changed much since yesterday. Ensembles continue to indicate a 500mb omega blocking pattern stubbornly remaining over central Canada, putting New England in the eastern troughing region. This will allow for several weak lows to spin up and move through or just near southern New England, leading to the cooler airmass and hit-and-miss showery weather to linger through at least Tuesday, if not Wednesday.

At this point, Monday looks to be the wettest day of the early week as the first closed low moves through southern New England. We'll likely see a few rounds of showers, possibly a rumble of thunder or two, with no one area guaranteed to remain completely dry. With the cooler airmass locked into place overhead and onshore flow, afternoon highs remain below normal, in the lower 60s across eastern and northern MA and up to 70 across the CT River Valley.

KEY MESSAGE 3...High uncertainty regarding the end of next week, but could be dry and unseasonably warm or more damp with seasonable temperatures.

Uncertainty remains quite high for the second half of next week. Ensemble guidance is favoring a warmer and drier solution, with indications that a low could spin up off the southeastern US coast and remain south of the 40N/70W benchmark. If this is the case, then temperatures could soar well above seasonable, into the mid 80s, close to 90 in the CT River Valley. A few models are showing the low could pass north of the benchmark, leading to more showery and cooler conditions. However, this is still almost a full week out, with plenty of time for guidance to come into better consensus.

AVIATION /18Z SATURDAY THROUGH THURSDAY/

Forecaster Confidence Levels...

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

Through 00Z: Moderate confidence.

Mainly MVFR ceilings. IFR is possible for the east terminals, though it should be off and on. Rainfall ends from NW to SE by 00Z. N-NE wind gusts subside generally from west to east after 20Z with ceilings trending VFR as well. BOS should start seeing improvements around 22Z.

Tonight: High confidence.

MVFR with moderate rain and NE winds 15-25 kt / gusts 35-40 kt Cape and Islands early, but conditions improve to widespread VFR by 04z Sunday. Winds shift to N/NW and decrease significantly to around 5-10 kt, occurring soonest in northern MA.

Sunday and Sunday Night...VFR. Generally a light westerly wind, with local seabreezes late morning into the afternoon.

KBOS...High confidence in trends. Moderate confidence in timing.

KBDL...High confidence in trends. Moderate confidence in timing.

Outlook /Monday through Thursday/...

Monday: Mainly VFR, with local MVFR possible. Chance SHRA.

Monday Night: VFR.

Tuesday: VFR. Chance SHRA.

Tuesday Night: VFR.

Wednesday: VFR. Breezy. Slight chance SHRA.

Wednesday Night through Thursday: VFR.

MARINE

Forecaster Confidence Levels...

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

*Dangerous Marine Conditions Expected into Early Tonight*

A powerful storm system is expected to bringing strong northeast winds, rough seas, and moderate rain to the waters this afternoon.

NE winds come around to northerly this evening into the gale- force range, decreasing further tonight. Storm Warnings for most of the waters, with the exception of Boston Harbor and Narragansett Bay where there are Gale Warnings. Will likely be able to downgrade the Storm Warnings to Gale Warnings some time this evening.

High winds and built up seas will bring high surf to the surf zones today along the east facing beaches. If you are venturing out to the beach, stay a safe distance for jetties.

Outlook /Monday through Thursday/...

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

Monday Night: Winds less than 25 kt. Seas up to 5 ft.

Tuesday: Winds less than 25 kt. Local rough seas.

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

Wednesday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers.

Wednesday Night: Winds less than 25 kt. Areas of rough seas. Chance of rain showers.

Thursday: Winds less than 25 kt. Rough seas up to 9 ft. Slight chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...Wind Advisory until 8 PM EDT this evening for MAZ004>007- 012>021-023-026. High Wind Warning until 8 PM EDT this evening for MAZ022-024. RI...Wind Advisory until 8 PM EDT this evening for RIZ001>008. MARINE...Gale Warning until 8 PM EDT this evening for ANZ230-236. Storm Warning until 8 PM EDT this evening for ANZ231>235-237- 250-251-254>256-280>283.