Cape Cod Bay Alt Marine Forecast
| Today...Sw Winds Around 5 Kt, Becoming Ne This Afternoon. Seas Around 2 Ft. Wave Detail: Se 2 Ft At 10 Seconds And Sw 1 Foot At 3 Seconds. Patchy Fog. Snow. Rain This Afternoon. Vsby 1 Nm Or Less. |
| Tonight...Ne Winds 5 To 10 Kt, Becoming N 10 To 15 Kt After Midnight. Seas Around 2 Ft. Wave Detail: N 2 Ft At 3 Seconds And E 1 Foot At 7 Seconds. Patchy Fog. Snow. Rain In The Evening. Vsby 1 Nm Or Less. |
| Mon...W Winds 10 To 15 Kt, Becoming Sw 15 To 20 Kt In The Afternoon. Gusts Up To 25 Kt. Seas 2 To 4 Ft. Wave Detail: W 3 Ft At 4 Seconds And Ne 1 Foot At 6 Seconds. Patchy Fog In The Morning. Snow Likely In The Morning. |
| Mon Night...W Winds 20 To 25 Kt, Diminishing To 15 To 20 Kt After Midnight. Gusts Up To 30 Kt. Seas 3 To 5 Ft. Wave Detail: W 3 Ft At 4 Seconds And E 1 Foot At 5 Seconds. Light Freezing Spray After Midnight. |
| Tue And Tue Night...W Winds 15 To 20 Kt With Gusts Up To 30 Kt. Seas 2 To 4 Ft. Wave Detail: W 3 Ft At 4 Seconds And S 1 Foot At 8 Seconds. Light Freezing Spray. |
| Wed...Sw Winds 10 To 15 Kt With Gusts Up To 25 Kt. Seas 2 To 4 Ft. Wave Detail: W 2 Ft At 5 Seconds And Se 1 Foot At 9 Seconds. |
| Wed Night And Thu...Sw Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 3 To 4 Ft. A Chance Of Showers. |
| Thu Night...W Winds 15 To 20 Kt With Gusts Up To 30 Kt. Seas 3 To 4 Ft. Light Freezing Spray. 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 358am EST Sunday Jan 18 2026 .WHAT HAS CHANGED... Snow accumulations increased and winter weather advisories expanded to include the rest of southern New England except Nantucket. Total snow accumulations of 2-6" expected with localized 7" amounts possible across eastern MA/RI. Heaviest snow occurs between 5 pm this evening and 1 am Monday...but some snow showers may linger into the Monday morning commute especially across eastern Massachusetts. No other significant changes made to the forecast. .KEY MESSAGES... - Plowable snow today-tonight with total accumulations of 2-6" with localized 7" amounts possible across eastern MA/RI. Heaviest snow/worst of the travel conditions between 5 pm and 1 am...but snow showers may linger for the Monday am commute. - Arctic cold front sweeps across the region Monday night bringing well below normal temperatures and bitterly cold wind chills & temps. The peak of the cold weather will be Tuesday into Wednesday am. - Milder temps arrive Wednesday night-Thu with perhaps a brief period of light snow showers or even light rain showers near the coast. - Another shot of very cold air works into the region behind a cold front Thu night into Fri. KEY MESSAGE 1...Plowable snow today-tonight with total accumulations of 2-6" with localized 7" amounts possible across eastern MA/RI. Heaviest snow/worst of the travel conditions between 5 pm and 1 am...but snow showers may linger for the Monday am commute. Deepening shortwave near a strong thermal boundary over the south triggers cyclogenesis off the coast of the Carolinas early this morning. Surface low quickly tracks northeast as the parent trough becomes negatively tilted over the Great Lakes. Low pressure will be slow to deepen as upper level energy will be somewhat stretched and elongated along a broad baroclinic zone offshore. Some modest deepening of the low center will occur as the trough goes negative and the right entrance region of a 180kt jet moves over the low center. Models have come into better agreement on the track of the storm, taking the center of the low SE of the 40 70 benchmark from 00z-06z Monday. Despite the weaker low center (~995mb) guidance continues to increase Quantitative Precipitation Forecast across the region with 0.5-0.7" for SE MA and the Cape/Islands and 0.2-0.5" along and NW of I-95. Periods of mainly light snow develop this morning and continue at times into the afternoon...but a lull in the activity is possible especially north of I-90. The steadier/heavier snowfall will arrive late this afternoon and especially tonight across eastern MA/RI. Looking at some strong midlevel frontogenesis resulting in ample lift in the DGZ. Guidance shows mid level cooling NW of the 850mb low as it tracks SE of the region. This cooling results in the DGZ growing a depth of 2kft during the afternoon to around 6kft through the evening and overnight. At the same time, 700mb omega of -10 to -15 ubar/sec means vigorous lift will be present resulting in bands of moderate to perhaps heavy snow overnight. Highest chance of more consistent moderate/heavy snowfall rates will be across eastern MA/RI. The highest snow totals are still expected across eastern MA/RI, where strong mid-level forcing and temperatures near or below freezing will overlap for the longest duration. Snow totals in this area will range from 3-6 inches, with localized 7" amounts possible. Would not be surprised if this band extended into parts of central MA/northeast CT where temps are colder and there will be better snow ratios. While there will be good forcing over Nantucket and Block Island, temperatures will likely be too warm for significant accumulations, but a slushy inch remains possible. Across CT and into western MA, the mid-level forcing is not quite as strong, but lower temperatures will allow for 2-5 inches. Have opted to include the rest of western and north central MA in the advisory. While forcing will be less in these areas, higher ratios will contribute to greater snowfall accumulations. While the steady snow ends before daybreak Mon, a period of lingering snow showers are possible especially across eastern MA through 15z. Guidance shows low level convergence and a bit of instability which could pair to produce areas of snow showers and light snow into MLK day. In summary...periods of snow overspread the region this morning and continue at times this afternoon but a lull in the activity is possible for a time especially north of I-90. Heaviest snow rates arrive later in the afternoon and especially tonight with the potential of 1"+ per hour snow fall rates. Otherwise...becomes breezy with partial sunshine returning by Monday afternoon ahead of an arctic cold front. High temps will be in the upper 20s to the middle 30s KEY MESSAGE 2...Arctic cold front sweeps across the region Monday night bringing well below normal temperatures and bitterly cold wind chills & temps. The peak of the cold weather will be Tuesday into early Wednesday morning. The models are still in very good agreement in an arctic cold front crossing the region Monday night. This will bring a shot of arctic air and well below normal temperatures to the region. 850T will drop to between -18C and -20C with the cold peaking Tuesday into early Wed. Gusty west winds will result in wind chills below zero to the single digits. High temps Tuesday will only be in the upper teens to the middle 20s with low temps Tuesday night mainly in the single digits to the lower teens. This shot of arctic air will be short-lived as high pressure shifts to our east by Wed. We should see high temps recover into the middle 20s and lower 30s by Wednesday afternoon...which is still below normal. KEY MESSAGE 3...Milder temps arrive Wednesday night-Thu with perhaps a brief period of light snow showers or even light rain showers near the coast. Low pressure tracking across Quebec will result in much milder air working back into the region on southwest flow. We may see a period of light snow showers in the warm air advection pattern and perhaps even light rain showers near the coast as the boundary layer warms. Regardless...these rain/snow showers will likely be short-lived and not expecting a significant precipitation event. KEY MESSAGE 4...Another shot of very cold air works into the region behind a cold front Thu night into Fri. Another shot of very cold air works into southern New England behind a strong cold front Thu night into Fri. Highs may be held in the upper 20s and lower 30s on Fri but with mainly dry weather. Marine Today and tonight...High Confidence. Residual seas of 5-8 feet on the southern waters and 3-6 feet on the eastern waters is the basis for a continued Small Craft Advisory on the outer waters, which is in effect through Sunday morning. Coastal storm passes off shore today, bringing a rain/snow mixture and poor visby conditions. Brief lull in advisory level conditions, seas fall below 5 feet with light winds. Increasing wind speed/gusts with seas coming up late tonight into early Monday, likely will need to be handled with a renewed Small Craft Advisory. Outlook /Monday Night through Thursday/... Monday Night: Moderate risk for gale force winds with gusts up to 40 kt. Rough seas up to 12 ft. Freezing spray. Tuesday: Low risk for gale force winds with gusts up to 30 kt. Areas of rough seas. Freezing spray. Tuesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas. Freezing spray. Wednesday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of seas approaching 5 ft. Wednesday Night: Strong winds with gusts up to 30 kt. Areas of rough seas. Chance of rain showers. Thursday: Strong winds with gusts up to 30 kt. Areas of rough seas. Slight chance of rain showers. NOAA Boston MA Office: Watches - Warnings - Advisories CT...Winter Weather Advisory from 7am this morning to 7am EST Monday for CTZ002>004. MA...Winter Weather Advisory from 7am this morning to 7am EST Monday for MAZ002>023-026. RI...Winter Weather Advisory from 7am this morning to 7am EST Monday for RIZ001>007. Marine Small Craft Advisory until 10am EST this morning for ANZ235- 237-250. Small Craft Advisory until 7pm EST Monday for ANZ254>256. |
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