Nantucket Sound Marine Forecast
| Overnight...Se Winds 5 To 10 Kt. Seas Around 2 Ft. Wave Detail: E 1 Foot At 4 Seconds And Se 1 Foot At 7 Seconds. |
| Mon...Se Winds Around 5 Kt. Seas Around 2 Ft. Wave Detail: Se 1 Foot At 7 Seconds. |
| Mon Night...S Winds 5 To 10 Kt. Seas Around 2 Ft. Wave Detail: S 1 Foot At 4 Seconds And E 1 Foot At 7 Seconds. Patchy Fog. Vsby 1 To 3 Nm, Decreasing To 1 Nm Or Less After Midnight. |
| Tue...Se Winds 5 To 10 Kt. Seas Around 2 Ft. Wave Detail: Se 2 Ft At 8 Seconds And Se 1 Foot At 3 Seconds. Patchy Fog In The Morning With Vsby 1 To 3 Nm. |
| Tue Night...Se Winds Around 10 Kt. Seas Around 2 Ft. Wave Detail: Se 2 Ft At 8 Seconds And Se 1 Foot At 4 Seconds. |
| Wed...E Winds 10 To 15 Kt. Seas Around 2 Ft. Wave Detail: E 2 Ft At 3 Seconds And Se 2 Ft At 7 Seconds. A Chance Of Showers In The Afternoon. |
| Wed Night...E Winds 10 To 15 Kt. Seas Around 2 Ft. Showers Likely. |
| Thu...Ne Winds 10 To 15 Kt. Seas 2 To 3 Ft. Showers Likely. |
| Thu Night...Ne Winds 10 To 15 Kt With Gusts Up To 20 Kt. Seas 2 To 4 Ft. A Chance Of Showers. |
| Fri...Ne Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 3 To 5 Ft. A Chance Of Showers. |
| Fri Night...Ne Winds 15 To 20 Kt With Gusts Up To 25 Kt. Seas 4 To 5 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 953pm EDT Sunday September 15 2024 Synopsis Strong area of high pressure over the northeast will continue the dry and quiet weather through Tuesday. A broad low brings our next shot of unsettled weather mid to perhaps late in the week. Risk for showers greatest along the south coast. Turning drier late in the week and heading into the weekend with near to cooler than seasonable temperatures. Near Term - Until 6am Monday Morning 955 PM Going forecast still looks on track, and other than incorporating current obs in the forecast, no significant changes were needed. Temps have cooled off into the mid to upper 50s for southeast MA and portions of RI, and in the lower to mid 60s more common north and west of I-95. Still have several more hrs of good radiational cooling ahead of us, and that could support patchy fog development in the CT Valley and around the I-495 corridor in eastern MA where radiational fog is more favored to develop. Previous discussion... High pressure across SNE will provide clear skies and light to calm winds setting the stage for excellent radiational cooling conditions. Lows will drop into the 40s in the traditional colder radiator locations, otherwise low-mid 50s. Current dewpoints are higher than the forecast low temps so we expect patchy radiation fog to develop, especially in the CT valley and portions of eastern MA. Short Term - 6am Monday Morning Through Monday Night Monday... Center of high pressure shifts east of New England but ridging extends west across the region through Monday night. Expect lots of sunshine again although high clouds will begin to overspread the region from the south and west during the afternoon. Slight warming in the low levels so it'll be another warm day with highs possibly reaching low- mid 80s in the CT Valley and interior NE MA, with mid-upper 70s closer to the coast. The column is pretty dry with axis of lower PWATs (Precipitable Waters) across SNE so mixing will result in dewpoints dropping into the 40s and lower 50s. Monday night... High clouds well north of sub-tropical low pressure will continue to increase and thicken across SNE through the night. Also, increasing shallow low level moisture will lead to development of stratus and fog near the south coast. More cloud cover will lead to milder temps with lows ranging through the 50s. Long Term - Tuesday Through Sunday Highlights * Another dry and mild day Tue, but will have increasing cloudiness. * Unsettled mid to perhaps late in the week with showers. Confidence highest along the immediate south coast. Northern periphery of precipitation shield still questionable at this point. Temps trending more seasonable. * Turning drier this weekend Tuesday... A ridge still builds from New England into the Great Lakes region early on Tue. The ridge axis shifts offshore toward Nova Scotia by late Tue, while the cutoff over the TN/OH Valley slowly rotates northward. High pressure nudges into southern New England from just south of Nova Scotia on Tue. Dry and quiet weather expected with high pressure still controlling the weather. Will see increasing high clouds as the day progresses ahead of the next system impacting our region. Can see this quite clearly per the 500-300 hPa RH with deterministic guidance, but think there will be breaks of sun, especially earlier in the day. Mild once again with high temps ranging from the mid 70s to the mid 80s. Tuesday Night through Friday... Cutoff over the OH/TN Valley initially will gradually rotate northeastward toward the Mid Atlantic. A shortwave lifts toward southern New England on Wednesday on the eastern side of the cutoff before lifting through/offshore by Thu. Still may have the cutoff south of our region on Fri or absorbed into a trough, lot of uncertainty with hows things evolve. A broad low lifts toward our region Tuesday Night into Thu before shifting offshore. This will be our next opportunity for showers across southern New England. Main change I've made from the NBM is to slow down the progression of Probability of Precipitation as the NBM is much too fast/high in bringing chances in based on the consensus of deterministic guidance Tuesday Night through much of Wed. Really think that Wedpm through Thu NBM much more dialed in as this coincides with the placement/timing of a 20-30+ kt 925 hPa E to NEly low level jet. This is also where we tap into 1-2+ inch PWATs. At this point most confident in precipitation amounts/chances for the immediate south coast, whereas think there could be a tight N/S gradient with little if any precipitation along/north of the MA Turnpike. Tried to highlight this with higher chances of precip, but let NBM take over with lower chances further north given there is still uncertainty on where the jet lines up and how far north things track. Other change made from the previous forecast was to remove the Day 4 ERO in collab with WPC. Antecedent conditions have been quite dry leading into this event. So, would take a fair amount of rainfall for flash flooding. Ensembles still in the two camps of EPS/GEPS being much wetter than the GEFS. At this point 24 hr probs of at or above 1 inch in a 24 hr period are low to mod (10-50 percent) centered mainly by the Thu timeframe, while the GEFS is still nil. Even with the wetter end of guidance (GEPS) the interquartile range for our area is anywhere from 0.25 to 2 inches of rain, which is much needed at this point. Highest amounts still centered more toward the south coast for this timeframe. High temperatures trending near to cooler than seasonable through this timeframe with the prolonged easterly flow. Fair amount of uncertainty on Fri on if things clear out a bit quicker with high pressure nudging in from the north. Due to the uncertainty have just stuck with the NBM for now, which keeps slight chances of precip. Saturday... Ridge axis builds from the Mississippi River Valley into the Great Lakes region. Though there still are questions on where the upper trough/cutoff in the prev period is located. High pressure nudges in or is overhead during this period. Turning drier during this timeframe with high pressure back in control. Will definitely feel more like fall with high temps generally in the 60s. Marine Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Tonight through Monday night...High confidence. High pressure over the waters will result in favorable boating conditions with winds below 20 kt, varying from E to S, and seas 3 ft or less. Areas of marine fog expected to develop over south coastal waters Monday night leading to reduced vsbys. Outlook /Tuesday through Friday/... Tuesday: Winds less than 25 kt. Tuesday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers. Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Rain showers likely. Thursday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. Thursday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers. Friday: Winds less than 25 kt. Areas of rough seas. Slight chance of rain showers. NOAA Boston MA Office: Watches - Warnings - Advisories CT...None. MA...None. RI...None. Marine None. |
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