textproduct: Boston / Norton

WHAT HAS CHANGED

Added small craft advisories for the waters adjacent to Cape Cod and Nantucket tonight into Monday as northeast winds and seas build up. Otherwise, no significant changes.

KEY MESSAGES

- Overcast early with rain showers limited to the South Coast, Cape and Islands. Although still cloudy and cool for the Cape and Islands, decreasing cloudiness and more sunshine north and west by the afternoon.

- Clear and dry Monday and Tuesday, but with northeast onshore breezes for the Cape and Islands.

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

DISCUSSION

KEY MESSAGE 1...Overcast early with rain showers limited to the South Coast, Cape and Islands. Although still cloudy and cool for the Cape and Islands, decreasing cloudiness and more sunshine north and west by the afternoon.

Overcast skies blanket Southern New England early this morning. Though radar imagery shows echoes across a large portion of Southern New England, drier air below cloud base is limiting the spatial coverage of steadier light showers to a rough Chicopee-Willimantic- Newport line southward and westward. This cloud cover and areas of rain are being driven by a positively-tilted shortwave trough over eastern NY and an organizing surface cyclone just off the Delmarva Peninsula. One of the more significant changes compared to yesterday in terms of how these synoptic features evolve is that while the NAM- based guidance closed off this midlevel shortwave trough sooner, there is now consensus across the NWP suite in this shortwave not closing off until later this afternoon in eastern/southeast New England. This is a more optimistic outcome, especially as it pertains to the weather for today into Monday, as the surface cyclone near the Delmarva moves off towards the ENE today and passes far enough southeast of Nantucket to mitigate a longer-duration of rain showers, overcast and onshore winds that the NAM was offering yesterday.

Current area of rain showers should continue to shift southward and expanding southeastward through this morning. While this means decreasing rains in CT and western MA, it will lead to lowering cloud bases and at least intermittent rain showers for Block Island, the South Coast and the Cape and Islands. At least modest NE winds will accompany those showers, but rain showers probably won't end up being persistent and total QPF amts are up to a few hundredths. Temperatures are coolest for those locations today, and could struggle to reach the low 50s. Further north and west, we should see mid-level overcast persist this morning but with decreasing cloudiness late this morning to the afternoon, leading to the warmest temperatures in the upper 50s to even some lower 60s in the CT and Merrimack Valleys. Eastern coastal MA will be contending with modest onshore breezes so these areas will still be running quite a bit cooler, in the upper 40s to lower 50s.

For tonight, high pressure to our northeast ridges back in, leading to clear skies and light northeast to northerly winds winning out for most of Southern New England. Meanwhile, low pressure southeast of Cape Cod will lead to increasing NE breezes and still partly to even mostly cloudy skies as moisture wraps around in the low's cold- conveyor-belt region. This creates a challenging low temperature forecast, as areas away from Cape Cod should radiate quite well after sundown with mid 30s to near 40, with a low risk for mist/fog especially in those locations in CT/RI/western MA where it rained early this morning. For the Cape and Islands, lows end up more in the low to mid 40s meaning little overall change from daytime highs, with NE winds around 10-15 mph.

KEY MESSAGE 2...Clear and dry Monday and Tuesday, but with northeast onshore breezes for the Cape and Islands.

Monday and Tuesday are shaping up to be absolutely spectacular, chamber-of-commerce days as amplified shortwave ridging aloft develops and dry high pressure rebuilds back in. A bit breezy for the Cape and Islands both days, and onshore flow will keep eastern MA several degrees cooler too - lower 50s. Away from the eastern coast though, deep mixing and full sun should push highs into the 60s on both days, and some spot 70 degree readings could occur in the CT Valley. Winds are very light through a deep depth of atmosphere away from the east coast, and expect dewpoints to plummet into the upper 20s to mid 30s. Cool nights too, milder near the Cape and Islands (upper 30s-mid 40s lows) but in the mid 30s to low 40s away from the Cape.

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

The clear and dry weather pattern breaks down potentially as soon as Tuesday night as moisture wraps back westward and brings at least expanding cloud cover and perhaps some light rain showers and mist/drizzle. Overcast with intermittent showers Wednesday, but the better chance for welcomed rains occurs later Wednesday night and into Thursday as a shortwave trough over the Gt Lakes swings a cold front and possible secondary low pressure along it near the ME/NH coast Wednesday night into Thursday. Could even be a rumble or two of thunder with the front too. Ensemble 24-hr QPF probs with this frontal passage show high (70-90%) chances for at least a tenth of an inch, moderate (40-60%) chances for a half inch, with low (less than 30%) probs of an inch or more of rain. Thus mid to late in the week looks to offer our next chance at more active weather.

AVIATION /06Z SUNDAY THROUGH THURSDAY/

Forecaster Confidence Levels...

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

06z TAF Update:

Today: High confidence.

Rain showers with low-end VFR/MVFR ceilings over BDL early this morning shift southeast with improving conditions at BDL through this morning, but lower clouds and intermittent rain spread to mainly affect ACK and perhaps the Cape airports. Otherwise, VFR cloudiness elsewhere, much of which is mid-level clouds. Light W to NW winds early this morning to turn NE/E 5-10 kt.

Tonight: High confidence.

VFR, though some lower-end VFR cloudiness could still linger around the Cape and Islands. Low prob of patchy mist/fog in western MA/CT toward dawn in areas where it rained. Winds go light northerly for most; but NE/N winds increase to around 10-13 kt with gusts to 20 kt for the Cape and Islands by daybreak Monday.

Monday: High confidence.

VFR. NE-E winds under 10 kt for most, but NE winds over the Cape and Islands will be quite a bit stronger, around 10-15 kt with gusts 20-25 kt.

KBOS Terminal...High confidence in TAF. Light WNW winds to flip to NE around 13-15z and then E/ESE around 17z. Winds then return back to NE or even due north tonight.

KBDL Terminal...High confidence in TAF. Rain with initial MVFR ceilings improve by around 11z, with VFR ceilings and NE/E winds. Outside chance at 1-4 SM patchy mist overnight/early Monday.

Outlook /Monday through Thursday/...

Monday through Tuesday: VFR. Breezy.

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

Wednesday Night: Mainly VFR, with local IFR possible. SHRA likely.

Thursday: Mainly VFR, with local IFR possible. SHRA likely, slight chance TSRA.

MARINE

Forecaster Confidence Levels...

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

Other than offshore seas building up to around 5 ft today on the far southern waters, winds and seas should remain below SCA criterion through today. NE/E winds increase to around 10-15 kt, with gusts around 20 kt. Seas 3-5 ft, higher in the southern waters. Periods of showers over the southern waters thru this afternoon reducing visbys to around 4 miles in steadier rain.

NE winds then increase tonight and into Monday near and southeast of Cape Cod and Nantucket. NE winds should increase to around 20-25 kt in gusts overnight into Monday, with seas becoming around 4-6 ft, which prompted issuance of SCAs. Elsewhere, NE/N winds around 10 kt and seas less than 3 ft.

Outlook /Monday through Thursday/...

Monday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft.

Monday Night through 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.

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 2 AM to 8 PM EDT Monday for ANZ232- 254-255. Small Craft Advisory from 8 AM this morning to 8 AM EDT Monday for ANZ256.