textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

- Dry and seasonable through Tue night with gusty NE winds developing along the coast. Lows tonight and Tue night mainly in the 30s and 40s, with afternoon highs Tue in the upper 50s-middle 60s.

- Chances for rainfall towards coastal areas Wednesday into Thursday due to an offshore nor'easter well to our south. Main impacts from this system will be marine-based: rough seas, beach erosion, and strong winds.

DISCUSSION

KEY MESSAGE 1...Dry and seasonable through Tue night with gusty NE winds developing along the coast. Lows tonight and Tue night mainly in the 30s and 40s, with afternoon highs Tue in the upper 50s-middle 60s.

Dry and seasonable weather continues through Tue night. Large high pressure across eastern Canada coupled with low pressure off the North Carolina coast will result in an increasing pressure gradient. This will result in a N-NE winds increasing Tue into Tue night along the coastal plain. Northeast wind gusts of 20-30 mph are expected to develop along the I-95 corridor with 30-40 mph wind gusts for the Cape and Islands. In fact, Nantucket may see a few gusts on the order of 45+ mph and approach marginal Wind Advisory criteria.

We expect dry weather to prevail through Tue night outside the low risk for a few showers reaching Nantucket. We may see some low clouds at times develop towards the southeast New England coast, but the greater risk for eastern MA/RI may wait until very late Tue night.

Low temps tonight and Tue night will be mainly in the 30s and 40s. The mildest lows will be across the Cape/Islands, where gusty NE winds will hold overnight low temps in the middle 40s to the lower 50s. High temperatures on Tuesday will be in the upper 50s to the middle 60s. The warmest of those highs will be across the interior with the coolest temps will be towards the Cape and Islands given the marine influence.

KEY MESSAGE 2...Chances for rainfall towards coastal areas Wednesday into Thursday due to an offshore nor'easter well to our south. Main impacts from this system will be marine-based: rough seas, beach erosion, and strong winds.

Confidence remains high that an offshore nor'easter will remain mainly south of our region. The questions are: how close does it approach southern New England? And how quickly will it move past us?

The NAM continues to be the farthest west of most of the guidance. The majority of solutions keep this low pressure well south of the 40N/70W benchmark. There are large differences in timing, with the GFS on the slower end, and the ECMWF the most progressive. All things considered, there is a risk for showers across southeast MA and perhaps part of eastern RI sometime from Wednesday afternoon into Thursday morning. Most of southern New England will remain dry during this time. Total rainfall should be light, with perhaps Nantucket seeing around one quarter inch.

The main impacts from this nor'easter will be over the coastal marine areas. NE gales continue to be expected across the southern waters, as well as rough seas. Rough seas also expected across the eastern waters, but will not be quite as high. Persistent easterly fetch associated with these winds, along with building rough seas, will need to be monitored as well, as beach erosion along east- and northeast-facing beaches may become an issue.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Forecaster Confidence Levels...

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

Through Tuesday Night...High confidence.

Mainly VFR conditions continue through Tue, but some brief MVFR cigs may flirt with the Cape/Islands at times. Appears a greater risk for low clouds/MVFR cigs to overspread eastern MA/RI very late Tue night.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Wednesday through Saturday/...

Wednesday: Mainly VFR, with local MVFR possible. Windy with gusts up to 35 kt.

Wednesday Night: VFR. Windy with areas of gusts up to 30 kt.

Thursday through Thursday Night: VFR. Windy with local gusts up to 30 kt.

Friday through Friday Night: VFR. Breezy.

Saturday: VFR.

MARINE

Forecaster Confidence Levels...

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

Through Tuesday Night...High confidence.

High pressure over eastern Canada will combined with low pressure off the North Carolina coast. This will result in an increasing NE pressure gradient and increasing winds through Tue night. Strong small craft headlines remain posted for our northern waters with gale warnings for our southern waters. NE wind gusts of 30-40 knots are expected, strongest of which will be for our southern waters where a few gusts near 45 knots are possible. Seas should build to between 7 and 13 feet by daybreak Wed with the highest across our southern-most outer waters.

Outlook /Wednesday through Saturday/...

Wednesday: Moderate risk for gale force winds with gusts up to 40 kt. Rough seas up to 15 ft. Chance of rain showers.

Wednesday Night: Strong winds with gusts up to 40 kt. Rough seas up to 14 ft. Chance of rain showers.

Thursday: Low risk for gale force winds with gusts up to 35 kt. Rough seas up to 13 ft. Chance of rain showers.

Thursday Night: Strong winds with gusts up to 30 kt. Rough seas up to 12 ft.

Friday: Strong winds with areas of gusts up to 30 kt. Rough seas up to 13 ft.

Friday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Rough seas up to 13 ft.

Saturday: Winds less than 25 kt. Rough seas up to 12 ft.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 8 AM Tuesday to 4 PM EDT Wednesday for ANZ230-236. Gale Warning from 8 PM this evening to 8 PM EDT Wednesday for ANZ231>235-237-254>256-281>283. Small Craft Advisory from 8 PM this evening to 8 PM EDT Wednesday for ANZ250-251.