textproduct: Boston / Norton

WHAT HAS CHANGED

No significant changes.

KEY MESSAGES

- A cold front brings the return of heavy rain and gusty winds Sunday night and Monday.

- Still unsettled late in the week with periods of showers and storms.

DISCUSSION

KEY MESSAGE 1...A cold front brings the return of heavy rain and gusty winds Sunday night and Monday.

The mid-level ridge slowly breaks down over the next 24 to 48 hours as an anomalous low digs into the Ohio Valley and becomes cutoff. This will mean slow movement east placing SNE and the whole eastern seaboard beneath deep, moist SW flow. As a 30-45kt LLJ develops it advects 2+inch PWATs overhead (2 SD above normal). This combined with impressive dynamics from the cold front, placement beneath the RRQ of a 120kt upper jet, and some elevated instability will lead to a washout for Monday featuring widespread rain, heavy at times, along with gusty winds as that LLJ gets mixed down. Specific locations of heaviest rainfall totals are difficult to place at this junction, but a widespread half inch to inch of rain is likely, with ensembles showing chances of 2+ inches essentially nil. That being said, in this super moist airmass any given location could pick up a quick hitting 1"+ that may lead to street flooding.

KEY MESSAGE 2...Still unsettled late in the week with periods of showers and storms.

By Tuesday the trough axis moves into the maritimes and mid level ridging/building surface high pressure should keep rain at bay for the most part. Uncertain as to exactly when our next bout of unsettled weather arrives but the synoptic pattern looks to be active, so periodic shortwaves (rain/t-storm chances) are expected to move through mid to late week, and even continuing into the weekend for daily afternoon/evening rain chances.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Forecaster Confidence Levels...

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

12z TAF Update:

Today: High confidence.

Stratus dissipates for most by 14z to BKN/OVC VFR ceilings, though could linger into the aftn for Cape and Islands. SW/S winds around 10 kt with occasional gusts to 20 kt.

Sunday Night: Moderate confidence.

Conditions deteriorate to MVFR/IFR ceilings. Possible SHRA western New England around/after 02z, but may take until 06z or later from ORH eastward. SW winds around 10 kt, with Possible LLWS after 06z Monday.

Monday: Moderate confidence.

IFR in RA/+RA through the day. SW winds 10-15 kts with gusts 20 to 30 kts.

KBOS Terminal...Moderate confidence in TAF.

KBDL Terminal...Moderate confidence in TAF.

Outlook /Monday Night through Thursday/...

Monday Night: VFR. Breezy. Chance SHRA, slight chance TSRA.

Tuesday through Tuesday Night: VFR. Slight chance SHRA.

Wednesday: VFR. Chance SHRA, slight chance TSRA.

Wednesday Night: VFR. Slight chance SHRA, slight chance TSRA.

Thursday: VFR. Breezy. Chance SHRA, slight chance TSRA.

MARINE

Forecaster Confidence Levels...

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

Winds and seas below small craft advisory levels through Sunday. Winds and seas increase late Sunday night into early Monday morning across the southern and eastern waters. Seas 5-8 ft for the outer coastal waters, especially south. 5-7 ft seas stretch into portions of the inner souther waters. SW winds 15-20 kts with gusts around 30 kts. SCAs are in effect for the southern and eastern waters included the Buzzards Bay, Vineyard Sound, and Nantucket Sound starting early Monday morning. Elevated seas will keep SCAs around through Tuesday for the southern waters.

Outlook /Monday Night through Thursday/...

Monday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Rough seas up to 8 ft. Rain showers likely, slight chance of thunderstorms.

Tuesday: Winds less than 25 kt. Local rough seas. Slight chance of rain showers.

Tuesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers.

Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft.

Wednesday Night: Winds less than 25 kt.

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 8 AM Monday to 2 AM EDT Tuesday for ANZ232>234. Small Craft Advisory from 8 AM Monday to 2 PM EDT Tuesday for ANZ235-237-254. Small Craft Advisory from 5 AM Monday to 8 PM EDT Tuesday for ANZ255-256.