Cape Cod Bay Marine Forecast
| Tonight...Nw Winds 5 To 10 Kt, Becoming Se After Midnight. Seas 2 To 3 Ft This Evening, Then 1 Foot Or Less. Wave Detail: N 3 Ft At 6 Seconds And S 1 Foot At 8 Seconds, Becoming N 1 Foot At 6 Seconds And S 1 Foot At 8 Seconds. |
| Mon...S Winds 15 To 20 Kt With Gusts Up To 30 Kt. Seas 2 To 4 Ft. Wave Detail: S 3 Ft At 4 Seconds And N 2 Ft At 6 Seconds. Patchy Fog. Rain. Vsby 1 To 3 Nm In The Afternoon. |
| Mon Night...Sw Winds 10 To 15 Kt With Gusts Up To 25 Kt, Diminishing To 5 To 10 Kt After Midnight. Seas 2 To 4 Ft. Wave Detail: S 3 Ft At 5 Seconds And E 2 Ft At 10 Seconds. Patchy Fog In The Evening. Rain Likely In The Evening. |
| Tue...Sw Winds 5 To 10 Kt, Increasing To 10 To 15 Kt With Gusts Up To 20 Kt In The Afternoon. Seas 2 To 3 Ft. Wave Detail: S 3 Ft At 8 Seconds And Se 2 Ft At 9 Seconds. |
| Tue Night...W Winds 5 To 10 Kt. Seas 2 To 3 Ft. Wave Detail: S 2 Ft At 8 Seconds And Se 2 Ft At 9 Seconds. |
| Wed And Wed Night...Nw Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 3 Ft. Wave Detail: Nw 2 Ft At 3 Seconds And S 2 Ft At 7 Seconds. A Chance Of Rain. |
| Thu Through Fri Night...Nw Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 2 To 4 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. |
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Area Forecast Discussion National Weather Service Boston/Norton MA 420pm EDT Sunday Mar 23 2025 Synopsis Increasing cloud cover tonight as a frontal system spreads a round of interior snow to wintry mix into Monday morning, with plain rain expected for the coastal plain. A minor accumulation of snow and sleet is expected with very limited impacts Monday morning before transitioning over to plain rain in interior Southern New England. Drying out for Tuesday, but there is potential for another round of showers mid-week as a system tracks to the southeast of New England. Thursday trends drier with temperatures near to slightly below normal. A weak system brings chances for scattered showers Thursday night into early Friday. .NEAR TERM /UNTIL 3am MONDAY MORNING/... 415pm Update: Key Messages: * Decreasing northwest wind gusts by sundown. * Increasing cloud cover overnight, with lows upper 20s to mid 30s before slowly rising into the pre-dawn hours. Details: Still are dealing with some northwest gustiness out there this afternoon, but the magnitudes have been coming down and that will continue to be the case as we work towards sunset. Rather chilly day with current temps upper 30s to mid 40s combined with low RHs (down to 15% in some areas, 20-30% common). Visible satellite shows the leading edge of an increasing high cloud canopy advancing into the lower Hudson Valley and Catskills in New York. This is associated with a frontal system that will be setting its sigheights on Southern New England by early Monday morning. So for tonight expect decreasing northwest winds and becoming light/variable during the mid-evening hours. As low pressure begins to approach, expect winds to become SE around midnight and that will allow for slow but steady surface temperature warming near the coastlines. Some radiational cooling in interior Southern New England should allow for lows in the mid to upper 20s for most of the interior prior to precipitation breaking out after ~3-5 AM, while lows elsewhere in the coastal plain and cities reaching into the 30-34F range with slowly rising temps as SE winds bring a somewhat warmer maritime air component. .SHORT TERM /3am MONDAY MORNING THROUGH MONDAY NIGHT/... Key Messages... * Interior snow to wintry mix with minor snow accumulation before changing to rain. Other than a very brief period of wet snowflakes Monday morning, most of the coastal plain sees predominantly rain. * Gray/raw Monday for much of Southern New England with highs upper 30s to low 40s. Shield of steady precipitation then begins to move in during the pre-dawn to mid-Monday morning hours from west to east. The main change in terms of forecast guidance trends is for a slower arrival of precipitation, perhaps a consequence of the very dry air currently in place over Southern New England. Although surface temps may cool off with initial precipitation onset through wet-bulb cooling of initially drier air, which will help sustain surface sub- freezing air in interior Southern New England for a wintry mix of snow and sleet (some FZRA in the highest elevations), this wet-bulb cooling effect near the Boston- Providence I-95 corridor and coastal plain should be offset by several hours of modifying/slowly warming temps in the face of increased SE surface flow. So for the coastal plain, other than a short-lived period of wet snowflakes during the Monday morning commute, the majority of the precipitation associated with this system will fall in the form of rain. If any initial precipitation falls as snow for these areas (roughly inside of I-495 and I-95), it's likely that any coatings which develop will be quickly washed away by rains. Storm total rainfall for the coastal plain around a half to two thirds of an inch. Further inland, including the area north and west of I-95, this is where a period of more sustained wintry weather takes place, although this area will also gradually see a south-to-north transition over to plain rain with warming surface temps. Model soundings show a weak warm nose with max temps in that warm nose around 1-1.5 C with a shallow layer of sub-freezing air immediately beneath it to the surface. This suggests a light wintry mix of snow with refrozen sleet pellets at onset, which then gradually changes over to plain rain during the Monday late morning to afternoon period. There could be some really minor ice accretion in the highest elevations in the Berkshires Monday morning but forecast amounts and expected very limited impact (falling onto a light snowpack) to preclude the need for winter weather advisories. Forecast snow/sleet accumulations of up to a couple inches before the transition over to rain, and this rain will help wash this slushy minor accumulation away here as well. Monday is likely going to be a pretty raw day, with abundant cloud cover and rain, with precipitation coming to an end from west to east by the late afternoon to sundown period. Temps may only rise into the upper 30s/near 40 northern MA, to the mid 40s elsewhere. For Monday evening, although we do clear out in terms of precipitation, a dryslot trapping shallow moisture could allow for partly to mostly cloudy skies before improving late Monday night/early Tuesday. Lows in the mid 30s to near 40. Long Term - Tuesday Through Sunday Key Messages: * Potential for system to bring a round of showers Wednesday. * Scattered showers possible Thursday night into early Friday. * More unsettled weather possible for the weekend. Tuesday: Dry conditions prevail Tuesday with breezy westerly winds. Despite cooler 850mb temperatures, downsloping and periods of sunshine will bring high temperatures in the upper 40s to mid 50s across southern New England. Wednesday - Friday: An upper level trough remains anchored across the northeast with an embedded shortwave trough moving through the flow Wednesday. This will track a system near the region bring our next shot at seeing precipitation. Details still need to be ironed out especially with the track which will impact Quantitative Precipitation Forecast and precipitation chances. Ensemble guidance shows decent agreement among members with the surface low tracking southeast of southern New England. Probabilities for >0.10" of Quantitative Precipitation Forecast are highest across the Cape and Islands where they range from 50 to 70 percent across various ensemble guidance. Rain amounts will depend on how the surface low tracks, but overall this still looks like lighter rain event on most guidance. Thursday will feature a brief dry period with a transient area of high pressure building in from the south. Despite this, high temperatures will remain slightly below normal in the mid 40s to upper 40s. A weak embedded shortwave within trough aloft may bring another round of low coverage/scattered showers later Thursday into early Friday. The higher elevations of the interior may see a few snow showers. There is a low chance for light snow accumulation for the high points of the Berkshires overnight. Breezy conditions Friday with highs in the upper 40s to low 50s in most spots. Weekend: Ensembles suggest that the parade of shortwaves continue into next weekend. There is the potential for yet another area of low pressure later Saturday into Sunday. Ensembles even suggest a period of wintry precipitation at the onset, but details are far from certain at this time. Marine Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. 415pm Update: Overall high confidence. Small Craft Advisories issued for Monday into Monday night. For tonight, decreasing NW wind gusts to become light/variable, then winds become E-SE around 5-10 kt. SE winds then increase to around 15-25 kt with gusts to 30 kt Monday morning which continue into Monday afternoon. Winds becoming S and decreasing to around 10-15 kt Monday night. Seas decrease to around 3-4 ft all waters tonight, then increase toward Monday morning to around 4-8 ft, highest on the southern offshore waters. Rain develops Monday morning and continues into early Monday night, with visbys decreasing to 2-4 miles. Outlook /Tuesday through Friday/... Tuesday: Winds less than 25 kt. Local rough seas. Tuesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain. Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain. Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain. Thursday: Winds less than 25 kt. Areas of seas approaching 5 ft. Thursday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Friday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. NOAA Boston MA Office: Watches - Warnings - Advisories CT...None. MA...None. RI...None. Marine Small Craft Advisory from 7am to 8pm EDT Monday for ANZ230- 236. Small Craft Advisory from 7am Monday to 2am EDT Tuesday for ANZ231>235-237-251. Small Craft Advisory from 7am Monday to 5am EDT Tuesday for ANZ250. Small Craft Advisory from 7am Monday to 8am EDT Tuesday for ANZ254>256. |
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