Cape Cod Bay Alt Marine Forecast
|Overnight...E Winds 10 To 15 Kt, Becoming S 5 To 10 Kt. Gusts Up To 25 Kt. Seas 3 To 4 Ft. Areas Of Fog. Showers Likely With Areas Of Drizzle, Then A Chance Of Showers With Areas Of Drizzle. Vsby 1 To 3 Nm, Decreasing To 1 Nm Or Less.|
|Mon...W Winds 10 To 15 Kt, Becoming Nw 5 To 10 Kt In The Afternoon. Gusts Up To 25 Kt. Seas 2 To 4 Ft. Areas Of Fog. Vsby 1 To 3 Nm.|
|Mon Night...Nw Winds 5 To 10 Kt, Increasing To 10 To 15 Kt With Gusts Up To 20 Kt After Midnight. Seas 2 To 3 Ft.|
|Tue...Nw Winds 10 To 15 Kt. Gusts Up To 20 Kt In The Morning. Seas 2 To 3 Ft. A Chance Of Rain.|
|Tue Night And Wed...N Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 3 Ft. A Chance Of Rain.|
|Wed Night...N Winds Around 15 Kt With Gusts Up To 20 Kt. Seas Around 3 Ft.|
|Thu Through Fri Night...Sw Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 3 Ft. Seas Are Reported As Significant Wave Height, Which Is The Average Of The Highest Third Of The Waves. Individual Wave Heights May Be More Than Twice The Significant Wave Height.|
| Area Forecast Discussion|
National Weather Service Boston/Norton MA
956pm EST Sunday Dec 3 2023
Steady rain tapers off to lighter showers, drizzle and fog from south to north tonight. Mainly dry weather follows Monday with highs in the 40s to the lower 50s. We turn colder Tuesday and Wednesday with perhaps a brief period of rain/wet snow across eastern New England...but any amounts should be light. Milder temperatures return for next weekend with our next shot at widespread precipitation not until next Sunday and/or Monday.
Near Term - Until 6am Monday Morning
No major changes with this update. Low top showers and drizzle impacting the region at 10 AM, courtesy of low level moisture via onshore flow with surface low south of BID, combined with dry slot aloft trapping this low level moisture across SNE. Robust short wave moving across PA/NY this evening per water vapor imagery, will move across VT/NH/ME overnight. A few showers may impact our region from this feature, but primarily northern MA into northern New England. Steep mid level lapse rates streaming across SNE this evening within the dry slot. But not expecting much if any elevated convection given the lack of deep layer moisture for this instability to be realized.
Ptype will be all rain with temps above freezing at the surface and aloft. Although, chilly/raw with damp onshore flow, especially across southeast MA with ENE winds up to 25 mph. Previous discussion below.
* Steady rain tapers to showers/drizzle & fog tonight * Brief mix/change to snow confined to far NW/NC MA...little impact
Shortwave trough lifting across the eastern Great Lakes has backed the mid level flow this afternoon. At the same time...a high pressure system over Quebec has resulted in cool NE flow at the surface. Then end result in a classic setup for widespread rain as southwest flow aloft overruns the cool dome at the surface. Thermal profiles are still too warm though to support anything but rain across the vast majority of the region. The exception is the high terrain of far northwest MA and north central MA...where thermal profiles have become just cold enough for a brief mixture/change to wet snow. Any accumulations/impacts will be short-lived and very minor and should change back to mainly rain as precipitation intensity lightens.
The main shortwave energy lifts to our north tonight. This will allow the steadiest/heaviest rain to taper off from southwest to northeast as the night wears along. However...moist ENE low level flow will continue to result in shallow lift for areas of light showers/drizzle and fog. This will persist well into the overnight hours especially across central and eastern MA. Low temps will mainly be in the upper 30s to the lower 40s.
Short Term - 6am Monday Morning Through Monday Night
Key Points... * Considerable cloudiness Monday but nothing more than a spot shower * Highs Monday in the 40s to the lower 50s...milder south of I-90
Monday... Any lingering fog and drizzle across central and eastern New England will come to an end by mid morning. We will have light northwesterly flow behind the departing shortwave/low pressure system. Additional shortwave energy coupled with cold 500T will result in an abundance of clouds persisting. While we may see some peeks of sunshine...clouds will dominate. Airmass is not that cold though with 850T near -2C/-3C. However...weak northerly flow may keep the inversion somewhat in place across northern MA which may hold highs in the 40s. South of the MA Turnpike...feel there is a better chance areas get into the lower 50s.
Dry weather is pretty much on tap for Monday...but can not rule out a brief spot shower given upper level shortwave energy and cold pool(a region of relatively cold air) aloft. T
Monday night... Yet another piece of shortwave energy will be moving across the region Monday night. However...there is not much low level support for anything more than a scattered to broken deck of clouds and perhaps a brief spot rain/snow shower. Perhaps a bit better chance for a few rain/snow showers near daybreak towards the eastern MA coast with hints of an inverted trough trying to setup. The NAM seems to start this a bit earlier than most of the other guidance...so this might be delayed. Otherwise...generally dry Monday night with a scattered to broken deck of clouds and lows mainly in the 30s.
Long Term - Tuesday Through Sunday
* Trending colder Tuesday through Thursday
* Chance for some some nuisance snow across eastern MA/RI Tuesday night into Wednesday morning
* Trending warmer Friday into the weekend
Tuesday and Wednesday
Persistent northwest flow and low-level Cold Air Advection will begin a cooling trend on Tuesday. 925 hPa temps fall to around -5 Celsius on Tuesday afternoon which will support surface temperatures in the upper 30s to low 40s Tuesday afternoon. Cooler air aloft will also support steep-lapse rates that will allow for substantial cloud cover on Tuesday, so expect more clouds than sun on Tuesday afternoon. Tuesday night into Wednesday, mesoscale models are beginning to resolve an inverted trough feature associated with short-wave energy aloft. This feature is expected to be meandering somewhere off the east/southeast coast of southern New England Tuesday night through Wednesday. With temperatures falling to near freezing Wednesday morning, this feature may provide enough forcing to support a period of snow showers Tuesday night into Wednesday. Accumulations would likely be minimal given marginal surface temperatures, but some accumulations up to an inch or two are in the cards if temperatures are cool enough. Won't get too deep into the weeds regarding details given the uncertainty at the time range, but Wednesday morning will be a period to pay attention to early next week. We should have a better idea as more mesoscale/hi-res model guidance becomes available over the 24 to 36 hours. The rest of Wednesday will feature shower chances tapering off from northwest to southeast during the afternoon. Cold Air Advection continues to bring 925 hPa temps down below -5 Celsius. Thus, another raw afternoon with high temps likely confined to the 30s across the region.
Wednesday night and Thursday
The cooling trend is forecast to peak Wednesday night into Thursday morning with surface temps falling into the teens and low 20s pretty much region wide. The exception areas as always will be the coastal locations where the proximity to the relatively warmer ocean waters will allow for somewhat milder temperatures in the mid to upper 20s. Northwest flow will create a very dry air mass over the region on Thursday with PWATs (Precipitable Waters) less than 0.2 inches, thus expect more sun than clouds on Thursday afternoon. Chilly high temps again in the mid to upper 30s.
Thursday night through Saturday
A mid-level ridge axis builds east of southern New England Thursday night into Friday, this will allow return flow from the south to begin a warming trend. 925 hPa temps climb to around 0C on Friday afternoon which should support high temps in the low to mid 40s. Strong low-level WAA (Warm Air Advection - the movement of warm air) continues into Saturday and Sunday with progressively warmer temps each day. Models are honing in on a robust low-pressure system that is likely to bring substantial precipitation to portions of the northeast late next weekend/early next week.Vague details at this time range, but this looks to be the next opportunity for a substantial precipitation event.
Forecaster Confidence Levels:
Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent.
Small craft headlines continue tonight for E wind gusts of 20 to 30 knots this evening. These winds should diminish overnight as the shortwave departs...but may see another brief round of Small Craft Advisory wind gusts as winds shift to the west overnight across our southern waters. Seas of 3 to 6 feet continue across the open waters & fog will also reduce visibilities for mariners.
Monday and Monday night...High Confidence.
Winds shift to more of a NNW direction as low pressure tracks across across northern New England. Gradient weak enough to generally keep wind gusts below SCA (Small Craft Advisory) thresholds most of the time...but some 20+ knot gusts are expected. Lingering swell though will keep seas in the 3 to 5 foot range across our outer-waters...so still need SCA (Small Craft Advisory) headlines through Monday night for those locations.
Outlook /Tuesday through Friday/... Tuesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain.
Tuesday Night: Winds less than 25 kt. Chance of rain.
Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain.
Wednesday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain.
Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Thursday Night through Friday: Winds less than 25 kt.
NOAA Boston MA Office: Watches - Warnings - Advisories
CT...None. MA...None. RI...None.
Small Craft Advisory until 7am EST Monday for ANZ231>235-237- 251. Small Craft Advisory until 7am EST Tuesday for ANZ250-254>256.