Massachusetts Bay and Ipswich Bay Marine Forecast
| This Afternoon...Se Winds 5 To 10 Kt. Seas Around 2 Ft. Wave Detail: Se 1 Foot At 3 Seconds And Se 1 Foot At 7 Seconds. Isolated Showers. Vsby 1 Nm Or Less, Increasing To 1 To 3 Nm. |
| Tonight...Se Winds 5 To 10 Kt, Becoming S After Midnight. Seas Around 2 Ft. Wave Detail: Se 2 Ft At 7 Seconds And E 1 Foot At 3 Seconds. Areas Of Fog. Vsby 1 Nm Or Less. |
| Fri...S Winds Around 5 Kt, Becoming Se In The Afternoon. Seas Around 2 Ft. Wave Detail: Se 2 Ft At 7 Seconds. Areas Of Dense Fog In The Morning With Vsby 1 Nm Or Less. |
| Fri Night...S Winds 5 To 10 Kt. Seas Around 2 Ft. Wave Detail: Se 2 Ft At 8 Seconds And E 1 Foot At 4 Seconds. |
| Sat...Se Winds 5 To 10 Kt, Increasing To 10 To 15 Kt In The Afternoon. Seas 2 To 3 Ft. Wave Detail: Se 2 Ft At 4 Seconds And Se 2 Ft At 8 Seconds. A Chance Of Showers In The Morning, Then Showers Likely In The Afternoon. |
| Sat Night...S Winds Around 10 Kt, Becoming W After Midnight. Seas 2 To 3 Ft. Wave Detail: Se 2 Ft At 4 Seconds And Se 1 Foot At 7 Seconds. Showers Likely, Mainly In The Evening. |
| Sun Through Mon Night...Nw 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. |
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Area Forecast Discussion National Weather Service Boston/Norton MA 713am EDT Thu May 15 2025 Synopsis Weakening low pressure will bring scattered showers or thunderstorms at times through the end of the week as it reaches New England, but a majority of the time will be dry. Scattered showers or thunderstorms will be a possibility to start the weekend before a cooling trend and drier conditions move into the region to start next week. Near Term - Through Tonight 330am Update: Key Messages: * Scattered showers early in the morning move offshore. * Overcast and on the humid side. * Isolated to widely scattered afternoon showers/t-storms in the interior if clouds can break, some which could be slow-moving and be a localized heavy-downpour risk. Details: The axis of showers and embedded thunderstorms over interior SNE will be gradually shifting eastward into eastern MA and RI and Cape/Islands over the next couple hours. Could be some localized downpours in some of this activity but it should just make for difficult travel/reduced visby for morning commuters vs yield any street flooding concerns. This axis of rain showers continues moving offshore by mid-morning; in its wake is left a rather cloudy and humid warm sector in an amorphous/weak/"blah" sea-level pressure pattern. This occurs as an upper level disturbance works its way northeast into eastern NY and opens up as it does so. The main forecast challenges for today are related to the extent to which we can shake free of cloudiness, or if we can at all. BUFKIT profiles from the RAP/HRRR (High-Resolution Rapid Refresh) suggest that cloudiness should hang tough in eastern MA and RI, and it would also lead to more convectively-stable thermo profiles. It wouldn't take much mid- May sun angle to disperse this layer of cloudiness but I'm more pessimistic we'll see much of any breaks in eastern New England. There is more optimism we'll scatter out during the afternoon in interior Southern New England; and if that does occur then the risk for diurnally-driven scattered showers and thunderstorms could develop. There isn't much in terms of a lifting source given the above-described pressure pattern, other than weak upslope convergence against the interior hills. CAPEs (Convective Available Potential Energy - high values indicate potential for severe weather) are forecast around 700-1200 J/kg from HFD-ORH-BED north and west but would be of the tall, skinny type of CAPE profile with poor mid- level lapse rates. Some of the convective-permitting model output simulates some popup cells in that weakly unstable airmass. Severe weather is not expected. But since mid-upper flow weakens to under 20 kt thru a deep depth of atmosphere with the approach of the upper disturbance, and that warm cloud depths are around 10-11kft favoring precipitation efficiency, any storm which develops would be slow moving and be capable of heavy downpours and local heavy rain footprints, falling in an area which has been soaked of late. Probabilistic HREF 3-hourly Quantitative Precipitation Forecast progs show some solid probs (up to 50%) of 1" rainfall in 3 hrs from Worcester west. In a nutshell, could be some minor hydro issues in slow moving cells but shouldn't rise to the level of significant/flash flooding. Should see highs in the mid 60s coastal areas to the low-mid 70s, with better chance at mid 70s in the Berkshires and interior SNE with sustained breaks in cloudiness. Short Term - Friday 330am Update: Key Messages: * Stratus and areas of fog tonight, locally dense in some locations. * Should clear out Friday, and while generally dry, will watch for possible scattered thunderstorms in western New England late in the day. Better potential exists in NY. Details: Tonight: Diurnally-driven showers or storms should dissipate by early evening. Weak sea-level pressure pattern continues, with light to calm winds, a humid airmass with recent rainfall having occurred. Though I don't have the strongest conviction in ceiling/visby guidance of late, this is a favored setup for development of areas of fog and stratus. There's also been a history of fog/stratus in the mid-Atlantic states overnight tonight, which is where our airmass is coming from. NBM visby progs actually sock all of SNE in dense fog, so it's possible later shifts could consider doing fog statements or advisories if needed. Rather mild, but generally dry and on the humid side with lows in the mid 50s to lower to mid 60s. Friday: We probably will have quite a bit of stratus and fog to open Friday. Background weak subsidence owing to 500 mb height rises could lead to more uncertainty on when we can scatter out. Tried to show some optimism in clearing during the mid to late morning to a partly sunny look, and temps warming to well into the 70s to a few spot 80 degree readings; if clearing is delayed until the afternoon, we'll probably struggle to reach 80. Later in the day our western areas start to get into stronger height falls with the approach of a midlevel warm front. This front will really help steepen lapse rates in the 850-500 mb layer, and there's some potential for a few rumbles of thunder during the late-afternoon stemming from a more active convection pattern in the Gt Lakes. Think a better chance for more robust convection develops in central/southern NY with weakening activity if any here in SNE, and that's the more likely outcome, but a few solutions such as the high- res WRF windows offer potential for scattered storms after 21z working over the Berkshires. Long Term - Friday Night Through Wednesday Key Messages: * Severe thunderstorms are a possibility on Saturday * Drier and cooler to start next week Details... A warm front is expected to move through the region Saturday morning, and we will be in the warm sector behind it before a cold front moves through. Ensembles still showing some probs for some elevated surface CAPE across western and central MA that would favor some thunderstorms. Timing on the cold front's passage could affect just how favorable the environment could be for severe storms and their mode. Even with some of the higher res guidance starting to reach this period hinting at some more organized convection in the evening hours Saturday, it's still far enough out that this could change. Probs for higher shear across the interior are soundly above 50 percent, so a high shear low CAPE environment could be what these storms develop in. CSU ML guidance does indicate some slightly higher chances for severe weather in southern New England, though, so this will continue to be monitored. A cold front moving through is expected to usher in a drier airmass following the exit of the mid-level low. Mid-level ridging pushes its way in heading into midweek with surface high pressure shifting into southern New England, which should keep the region dry. Winds shift more to the NW and N. Guidance shows temperatures aloft cooling by around 10C from Saturday afternoon by Monday, continuing into Wednesday. Saturday and Sunday highs are expected to be primarily in the 70s, although Sunday is slightly cooler with the highest temperatures in the low to mid 70s. Once the cold front moves through, highs to start the week may settle more into the mid to upper 60s. Marine Forecaster Confidence Levels: Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. 330am Update: High confidence overall. E/SE winds remain below SCA (Small Craft Advisory) levels Thu and Fri. Seas will be building on the southern ocean waters where SCAs (Small Craft Advisories) still continue. Few showers or a thunderstorm possible early this morning, with areas of marine fog developing tonight and could linger into a good part of Fri. Outlook /Friday Night through Monday/... Friday Night: Winds less than 25 kt. Slight chance of rain showers, isolated thunderstorms. Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, isolated thunderstorms. Saturday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers. Sunday Night through Monday: Winds less than 25 kt. Areas of seas approaching 5 ft. NOAA Boston MA Office: Watches - Warnings - Advisories CT...None. MA...None. RI...None. Marine Small Craft Advisory until 4pm EDT this afternoon for ANZ235- 237. Small Craft Advisory until 1am EDT Friday for ANZ254>256. |
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