textproduct: Boston / Norton

WHAT HAS CHANGED

Adjusted Small Craft Advisories to start Monday morning and persist over the southern outer waters into Tuesday morning. Otherwise, no major changes.

KEY MESSAGES

- Skies continue to clear this afternoon into tonight across much of southern New England

- Dry and clear Monday

- Increasing clouds and light rain from the ocean waters Tuesday evening and Wednesday, but more active/unsettled weather develops Wednesday night and Thursday with much-needed rainfall.

DISCUSSION

KEY MESSAGE 1...Skies continue to clear this afternoon into tonight across much of southern New England.

High pressure works to reassert itself over the region as the low off to our south and east continues to pull away. Clouds have already cleared across much of western and central MA, CT, and parts of RI with some diurnal cu popping up in its wake. This widespread clearing will continue through the rest of today, reaching the Cape and Islands last. Spotty rain showers remain a possibility through this evening there, though the chance is decreasing as time goes on. Cloud cover there may linger through tonight, which will play a part in inhibiting radiational cooling there. Across the rest of southern New England, this clearing with high pressure will set the stage for a radiational cooling night, especially as already relatively light E to ENE winds may go calm. Some localized patchy fog is a possibility tonight in spots like Orange and Norwood, but the chance is quite low given how dry it is. The dryness will also limit the development of fog just about everywhere else tonight as well. Lows for much of the region will likely fall into the upper 30s, with spots that radiate more falling more to the mid 30s. Spots on the upper Cape could also get to the mid to upper 30s while the rest of the Cape and Islands can expect lower 40s with light onshore breezes.

KEY MESSAGE 2...Dry and clear Monday

High pressure fully reestablishes itself overhead Monday as upper level ridging starts to make its way into the region, and with the low lingering offshore SW, light NE winds persist through the day. These onshore winds will keep the immediate coastal areas across eastern MA cooler than the rest of the region despite the clear skies overhead; highs along the coast will remain mostly in the 50s. Cape Cod and the Islands should be on the lower end of the range with NE winds being slightly breezier there. Further inland, 925 mb temperatures also climb to around 10C. This with clear skies will allow temperatures to climb into the 60s with the CT Valley possibly reaching 70F.

KEY MESSAGE 3...Increasing clouds and light rain from the ocean waters Tuesday evening and Wednesday, but more active/unsettled weather develops Wednesday night and Thursday with much-needed rainfall.

Tuesday high pressure remains the dominating feature to start with mostly sunny skies in the morning. Even with sunny skies to start, temperatures will be a bit cooler than Monday, especially for central/eastern MA and RI where increasing easterly winds pull in cooler air off the ocean. This means highs in the low 50s along the immediate east coast while the CT valley remains in the upper 60s. The second half of the day we begin to transition into a more unsettled period. Ahead of an approaching shortwave, moisture is pulled back around the low offshore and onshore, moist flow will bring scattered light showers and drizzle to eastern MA/RI as early as Tuesday evening, lingering into and expanding on Wednesday.

The more robust round of widespread rain then arrives Wednesday night and Thursday as the better moisture and forcing arrives with a deep trough and moisture plume out ahead of it. The surface low initially over PA on Wednesday produces a secondary low along the frontal boundary that then crosses somewhere in the vicinity of SNE Thursday night. This generates a 30-45kt LLJ which together with the surface front, mid level PVA, and PWATs near 1" will lead to widespread moderate rainfall through as late as mid day Friday. Rainfall totals on the order of 1-2 inches are possible in spots, though it is too early to nail down where the heaviest rain will fall and when. Ensemble probabilities of 1" inch of rain have increased to the 40-60% range. Toward next weekend, no big weather systems on tap but the lingering trough and cold pool aloft will likely lead to cooler than normal temperatures and diurnal rain/graupel showers possible at times.

AVIATION /19Z SUNDAY THROUGH FRIDAY/

Forecaster Confidence Levels...

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

18z TAF Update

Rest of Today and Tonight...High confidence.

VFR conditions for the rest of today and tonight. Very light showers may still graze part of the Cape and Islands this afternoon. Very localized patchy ground fog in the typically prone locations is possible very late tonight. However, the chance is low as it is very dry. Winds remain generally E through this afternoon, becoming light to calm overnight for most. Light NE breezes may continue over the Cape and Islands tonight, helping mitigate radiational cooling there.

Monday and Monday Night...High confidence.

VFR. Winds pick back up late Monday morning into the afternoon, remaining ENE at 5-10 kt. Slightly higher over the Cape and Islands with sustained winds to 15 kt possible with gusts around 20 kt. NE winds slacken Monday night, becoming calm in some areas.

KBOS Terminal...High confidence in TAF.

KBDL Terminal...High confidence in TAF.

Outlook /Tuesday through Friday/...

Tuesday: VFR. Breezy.

Tuesday Night: Mainly VFR, with local IFR possible. Slight chance SHRA.

Wednesday: VFR. Slight chance SHRA.

Wednesday Night through Thursday: VFR. SHRA likely.

Thursday Night through Friday: VFR. Breezy. Chance SHRA.

MARINE

Forecaster Confidence Levels...

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

Relatively calm conditions persist through the rest of today over the waters with seas 2-3 ft. Highest winds through the rest of today will remain over the southern outer waters and ocean waters, generally around 10-15 kt with an occasional gust to 20 kt more likely over the ocean waters.

NE winds start to increase tonight and into Monday near and southeast of Cape Cod and Nantucket. NE winds should increase to around 20-25 kt in gusts Monday morning, so Small Craft Advisories will be in effect starting 8 AM Monday. Elsewhere, NE/N winds around 10 kt and seas less than 3 ft. Some spotty showers may linger through late tonight into Monday morning further offshore.

For Monday night, seas will continue building to around 4-6 ft over the southern waters with NE winds gusting to 20-25 kt.

Outlook /Tuesday through Friday/...

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

Tuesday Night through Wednesday: Winds less than 25 kt. Areas of rough seas. Slight 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. Areas of rough seas. Rain showers likely, slight chance of thunderstorms.

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

Friday: Winds less than 25 kt. Areas of rough seas. Slight chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 8 AM to 8 PM EDT Monday for ANZ232. Small Craft Advisory from 8 AM Monday to 8 AM EDT Tuesday for ANZ254>256.