Cape Cod Bay Marine Forecast
| This Afternoon...N Winds 5 To 10 Kt. Seas Around 2 Ft. Wave Detail: N 2 Ft At 4 Seconds And E 1 Foot At 9 Seconds. |
| Tonight...N Winds 5 To 10 Kt. Seas Around 2 Ft. Wave Detail: N 2 Ft At 4 Seconds And Se 1 Foot At 9 Seconds. |
| Sun...Ne Winds Around 5 Kt. Seas Around 2 Ft. Wave Detail: Se 2 Ft At 11 Seconds And N 1 Foot At 4 Seconds. |
| Sun Night...S Winds Around 5 Kt. Seas Around 2 Ft. Wave Detail: Se 2 Ft At 11 Seconds And N 1 Foot At 4 Seconds. |
| Mon...S Winds 5 To 10 Kt. Seas 1 Foot Or Less, Then Around 2 Ft In The Afternoon. Wave Detail: S 1 Foot At 2 Seconds And Ne 1 Foot At 4 Seconds, Becoming Se 2 Ft At 10 Seconds And S 1 Foot At 3 Seconds. A Chance Of Rain. |
| Mon Night...Se Winds 10 To 15 Kt, Becoming S 15 To 20 Kt After Midnight. Seas 2 To 3 Ft. Wave Detail: S 2 Ft At 4 Seconds And Se 2 Ft At 10 Seconds. A Chance Of Rain In The Evening, Then Rain Likely After Midnight. |
| Tue...S Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 3 To 4 Ft. Rain. |
| Tue Night...W Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 3 Ft. A Chance Of Rain. |
| Wed...W Winds Around 10 Kt. Seas Around 2 Ft. |
| Wed Night...Sw Winds 5 To 10 Kt. Seas Around 2 Ft. A Chance Of Rain. 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 227pm EST Sat Dec 14 2024 Synopsis Strong high pressure will result in a dry but cold weekend. A shift to a more unsettled weather pattern next week with periods of precipitation possible. Temperatures trend above normal Tuesday through Thursday. Potential for another late week system; however, confidence is low in the details. Near Term - Through Tonight Near record high pressure over upstate NY will move over New England tonight. Rather tranquil weather will continue. With light winds and clear skies, except across portions of the outer Cape and Nantucket, expecting excellent radiational cooling conditions. Favored the lowest guidance for low temperatures over land. Thinking low temperatures about 7-10 degrees below normal for mid December. Short Term - Sunday Through Sunday Night Key Messages... * Dry through Sunday with below normal temperatures * Wintry mix late Sunday Night More of the same to start Sunday. Large high pressure shifts farther offshore, but still remains in control. The forecast for late Sunday night is complicated, and the details remain uncertain. These details will be crucial, as a subtle shift of a single degree in temperature will make a difference in precipitation type. Add in the timing errors for precipitation at all, and the result is a complicated forecast. The latest trend in the guidance is for a slower arrival timing, which makes sense given the large high pressure that should be just to our east. Even by daybreak Monday, surface MSLP should be 1035+ mb. Thus, it may be difficult to generate precipitation at all. Will trend the forecast to a slower timing, but further timing adjustments may be needed for Sunday night. In general for this update, thinking snow is the most likely type through about 2 AM, where it precipitates at all. Then a warming trend begins higher up in the atmosphere. Differences in the guidance, with the GFS (Global Forecast System) holding onto a colder solution in the idea of a weaker warm nose over a greater depth when compared to the NAM. The NAM had a shallower warm nose, but it was more potent. Both of these scenarios do depict the same pattern, one of a transition from snow to rain, with a period of freezing rain some time in between. Do not have enough confidence for a Winter Weather Advisory at this time. However, one may be issued with later forecasts as confidence in the timing and location of freezing rain increases. Increasing clouds during the afternoon, with even more clouds Sunday night. Below normal temperatures Sunday, ten trending closer to normal Sunday night. Long Term - Monday Through Saturday Key Messages: * Unsettled start to next week with some light frozen precipitation possible Monday morning * Drying out Wednesday before another low-pressure system produces substantial precipitation during the Wednesday night/Thursday time frame * Trending cooler next weekend with the potential for some unsettled weather Monday and Tuesday High pressure continues to slowly build east of southern New England during the first half of Monday. Southerly flow/warm advection west of the associated mid-level ridge axis is likely to support a period of light precipitation for portions of southern New England Monday morning into early Monday afternoon. With low temps in the low to mid 20s to start Monday, precipitation should fall as light snow as as temperatures through 850 hPa will be below freezing as well. However as we progress into mid- morning persistent warm advection will eventually result in 925 hPa temps climbing above 0 Celsius which will introduce a warm nose/melting layer in the column. With surface temps still well below freezing across interior/northwest MA, a period of freezing rain may be possible toward the end of the Monday morning commute for locations west of I-495. Elsewhere, surface temps should be edging above freezing as the warmer air aloft noses in, which should support any snow changing over to rain. Quite a tricky forecast as timing will be play a crucial role in potential frozen precipitation. Guidance has been trending toward a slower arrival of precipitation thanks to the large area of surface high pressure that's in place. Should the late trend continue, surface temps may have more time to warm limiting the potential for frozen precip. Consulting ensemble guidance, we find only a 10 to 20 percent chance for greater than 0.01 inches of ice accumulation and a 10 to 30 percent chance of snow accumulations greater than 1 inch for locations west of Worcester. Thus, a low impact event if it comes to fruition, but something we'll have to monitor over the next 36 hours or so. By Tuesday evening, a cold front approaching from the west will support another round of substantial rainfall with ensemble means coming in around 0.25 to 0.5 inches between Monday night and Tuesday morning. This will be accompanied by a warming trend as southwest flow ahead of the cold front helps 925 hPa temps rise close to 10 Celsius. This will support surface temps in the 50s on Tuesday. Temperatures return to normal by Wednesday morning (upper 20s/lower 30s) as the air mass behind the cold front settles over the region. Wednesday and Thursday Briefly drying out on Wednesday behind a weak surface cold front. Winds quickly shift from WNW to southwest early Wednesday allowing mild air to creep back into The Northeast, thus another mild afternoon in the mid to upper 40s. This will be followed by another frontal system pushing through the region with more rainfall. Latest guidances suggests the associated cold front and precipitation should be exiting the area Thursday afternoon, but timing at this time range is uncertainty. Friday and Saturday A polar air mass settles over The Northeast behind Thursday's frontal system. Models are in agreement with respect to below normal temperatures, but there is a bit of spread when it comes to precipitation chances. Some solutions support shortwave energy over Ontario/Quebec producing some chances for modest snow on Friday and Saturday. Ensembles suggest a 20 to 30 percent chance of 1+ inches of snow both Friday and Saturday, so confidence in snow is low at this times. Check back later this week for more details. Marine Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Through Sunday Night... A very strong high pressure moves over New England tonight, then offshore Sunday night into Monday. Light winds and seas expected. Low risk for some rainfall late Sunday night across the RI coastal waters. Outlook /Monday through Thursday/... Monday: Winds less than 25 kt. Slight chance of rain. Monday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of seas approaching 5 ft. Chance of rain. Tuesday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Rain likely. Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain. Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Rain. Thursday: Low risk for Small Craft Advisory winds with gusts up to 20 kt. Seas up to 5 ft. Rain likely. NOAA Boston MA Office: Watches - Warnings - Advisories CT...None. MA...None. RI...None. Marine None. |
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