Marine Weather and Tide Forecast for Tiverton, RI

NEAR TERM /UNTIL 6 AM THIS MORNING/
1015 PM update...

Winds have decoupled across much of the region as surface ridging building in from the west. With fresh snowpack and light winds temps have already fallen to lower single numbers to near zero in the colder spots across interior MA. As a result we lowered temps a bit with expected lows zero to -5F across interior northern MA and possibly even a few degrees colder in a few locations. Elsewhere lows zero to 10 above, except teens outer Cape and Islands. Given lighter winds, wind chill temps will not be as impacted as much as they could be, but still expecting minimum wind chills zero to -10F away from the south coast, with localized -10 to -15F wind chills over higher elevations.

Previous discussion...

Key Message

* Bitter cold temperatures across southern New England tonight with single digit low temperatures forecast across the region

* Cold Weather Advisory in effect for the north east slopes of The Berkshires and northern Worcester County

Tonight

Gusty northwest winds this afternoon gradually diminish/decouple after sunset. Clear skies, a fresh snow pack, and light winds should support very efficient radiational cooling that will allow temperatures to dip into the single digits for most of interior southern New England. Some locations across interior MA at the higher elevations may even approach 0. While winds will be on the lighter side, there will be at least some mechanical mixing that will limit a maximum radiational cooling effect, but nonetheless wind chill temperatures will be well below 0 across the interior overnight and into tomorrow morning. The coastal locations will get some mild relief from the proximity to the relatively warmer ocean, but will still experience single digit wind chill values or lower.

SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/
Key Messages

* Bitter cold temperatures continue tomorrow and peak tomorrow night

* Cold weather headlines likely again tomorrow night

Tomorrow and Tomorrow Night

The arctic outbreak peaks tomorrow and tomorrow night as 925 hPa temps continue to over at -15C or lower. Expect sunny skies across the interior north of I-90 tomorrow, but across CT, RI, and southeastern MA there will be increasing cloudiness as a plume of moisture at 850 hPa edges over the region. High temperatures will struggle to break out of the teens across the interior tomorrow, but the coastal locations will be a bit more mild in the low to mid 20s.
Steady west/northwest winds from 10-15 mph will add a wind chill factor that will have the day time temperatures feeling closer to the single digits/low teens than the teens and low 20s.

After sunset, the atmosphere decouples allowing temperatures to dip once again. Clouds over the southern half of the forecast area retreat south and east and also may produce some light snow over Nantucket/Marthat's Vineyard, but no substantial accumulations would be expected. Areas with cloud cover to begin with may not radiate as efficiently as they would otherwise on a clear night, but clearer skies across the interior will support the coldest temperatures during this stretch. Many locations will have single digit or negative single digit temperatures by Wednesday morning. With wind chill temperatures well below -15F, for several locations west of I- 95, cold weather headlines will likely be needed for a second night.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
Key Messages:

* Bitterly cold Wednesday morning followed by highs that only reach the lower 20s

* Single digit lows Wednesday night before temperatures begin to moderate Thursday, although still expected to be below normal

* Dry throughout aside from some stray snow shower chances towards the Cape Friday AM

Wednesday

An arctic airmass remains settled over the region before it begins to make its exit Thursday. Temperatures at 850 mb Wednesday continue to sit in the -25C to -20C range and forecast soundings indicate dry conditions with good mixing, continuing this cold trend. Ensembles show good probs for temperatures below 5F for Wednesday night particularly across the interior and towards the Merrimack Valley.
Wind chill values Wed PM could once again reach the negatives in some spots. Some mid to high level clouds could help keep temperatures from sinking as low as they are expected to for Tuesday night, but they continue to range from close to 0F to the low teens as you move from the interior to the coast.

Thursday and Friday

A ridge of high pressure progresses east of the region by Thursday, and milder air makes its way across southern New England.
Temperatures aloft are still low, but they improve to the -15C to - 10C range at 850 mb by the daytime hours. Highs are still expected to be in the 20s and 30s for both Thurs and Fri, but it's an improvement nonetheless. With the snowpack across much of the region and clearer skies Thursday night, lows are still likely to tank into the single digits and low teens outside of the Cape and Islands, as they don't have as significant of a snowpack and may see more cloud cover lingering during the overnight hours. Winds are expected to remain light and mostly from the W to NW through both days.

The shortwave associated with the winter weather in the southern US moves eastward Thursday night into Friday morning, however we're not expecting any significant impacts at this time. At most, some stray snow showers over the Cape could develop, but the signal in the ensemble guidance still varies a bit at this point. The ECMWF ensemble favors a drier solution while the Canadian is more aggressive on the chance for some precipitation.

Saturday through Monday

Temperatures continue to moderate and dry conditions continue through the weekend. Deep troughing over the SW US will encourage geopotential heights to rise over the SE US. Ensemble height anomalies also indicate height falls to our north and west, and an area of low pressure to the N and NE with high pressure to the SW at the surface is a favored outcome. So the difference between the building heights in the south and the falling heights in the north leading to this building pressure gradient at the surface will encourage the development of slightly stronger W to SW winds over the weekend with gusts up to 25 or 30 mph possible.

With the continued moderation of temperatures due to this SW flow, highs Sunday are expected to be above freezing for much of the region. Some spots could reach over 40F. Beyond this period, some low precipitation chances show up for later Monday, but nothing significant at this time.

AVIATION /06Z TUESDAY THROUGH SATURDAY/
Forecast Confidence Levels:

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

06z Update:

Today...High Confidence

VFR with high cloud developing this morning, cigs lowering to 8-10k ft during the afternoon. W wind around 10 kt.

Tonight...Moderate confidence.

Light snow overspreading Cape/Islands from ACK to HYA 01-03z with MVFR cigs and MVFR-IFR vsbys developing. Otherwise VFR with clearing from NW to SE. Light NW wind, up to 10 kt over outer Cape and ACK.

Wednesday....High confidence.

VFR. NW wind 5-15 kt.

KBOS TAF...High Confidence in TAF.

KBDL TAF...High Confidence in TAF.

Outlook /Wednesday Night through Saturday/...

Wednesday Night through Friday Night: VFR.

Saturday: VFR. Breezy.

MARINE
Forecaster Confidence Levels:

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

Tonight through Tomorrow Night

High confidence...

Small craft advisories remain in effect through tonight and tomorrow for the outer marine zones. Arctic air mass settles in tonight and persists through Wednesday supporting periods of freezing spray. Winds will be relatively modest in the 10 to 20 knot range out of the west/northwest with some gusts up to 25 knots. Seas generally ranging from 2 to 4 feet.

Outlook /Wednesday Night through Saturday/...

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

Wednesday Night: Winds less than 25 kt.

Thursday through Thursday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of snow.

Friday through Friday Night: Winds less than 25 kt.

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

BOX WATCHES/WARNINGS/ADVISORIES
CT...None.
MA...Cold Weather Advisory until 10 AM EST this morning for MAZ002- 004-008.
RI...None.
MARINE...Small Craft Advisory until 4 AM EST early this morning for ANZ235-237.
Small Craft Advisory until 4 PM EST this afternoon for ANZ250- 254>256.
Small Craft Advisory until 1 AM EST early this morning for ANZ251.