Marine Weather Net

Narragansett Bay Marine Forecast


REST OF TONIGHT

N
WINDS
5 - 10
KNOTS

TUE

N
WINDS
5 - 10
KNOTS

TUE NIGHT

SE
WINDS
5 - 10
KNOTS

WED

SE
WINDS
10 - 15
KNOTS

The Marine Weather Forecast In Detail:
ANZ236 Forecast Issued: 101 AM EST Tue Nov 29 2022

GALE WATCH IN EFFECT FROM WEDNESDAY AFTERNOON THROUGH THURSDAY EVENING
Rest Of Tonight...N Winds 5 To 10 Kt. Waves 2 To 3 Ft.
Tue...N Winds 5 To 10 Kt, Becoming Se In The Afternoon. Waves 2 To 3 Ft.
Tue Night...Se Winds 5 To 10 Kt. Waves Around 2 Ft.
Wed...Se Winds 10 To 15 Kt With Gusts Up To 25 Kt, Becoming S 20 To 25 Kt With Gusts Up To 35 Kt In The Afternoon. Waves 2 To 3 Ft, Increasing To 4 To 7 Ft In The Afternoon. Rain. Vsby 1 To 3 Nm.
Wed Night...Sw Winds 20 To 25 Kt With Gusts Up To 45 Kt, Becoming W 10 To 15 Kt With Gusts Up To 30 Kt After Midnight. Waves 4 To 6 Ft, Decreasing To 2 To 3 Ft After Midnight. Rain. Vsby 1 To 3 Nm.
Thu And Thu Night...Nw Winds 15 To 20 Kt With Gusts Up To 30 Kt. Waves 2 To 3 Ft.
Fri And Fri Night...W Winds 5 To 10 Kt, Becoming Sw 10 To 15 Kt With Gusts Up To 20 Kt.
Sat And Sat Night...Sw Winds 15 To 20 Kt, Becoming W 10 To 15 Kt. Gusts Up To 25 Kt. 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
115am EST Tuesday Nov 29 2022

Synopsis
High pressure builds in this evening, allowing for a chilly night tonight followed by mostly sunny and seasonable conditions on Tuesday. Winds increase from the south out ahead of a strong cold front that crosses Southern New England late Wednesday into overnight, with the potential for brief downpours and strong to perhaps damaging winds. Gusty conditions continue on Thursday along with cooler temperatures. A low pressure system brings our next chance for precipitation on Saturday but the overall weather pattern features quiet and seasonable conditions.

Near Term - Until 6am This Morning
950 PM

High pressure building in from the west will result in quiet but chilly weather overnight. Skies will generally be mostly clear outside of a bit of strato-cu spilling over into the distant interior at times. There also will be some ocean effect clouds developing overnight across the Cape/Nantucket given modest SST differential with the northerly flow.

Low temps overnight should drop into the 20s to the lower 30s by daybreak as northerly winds gradually diminish. The mild spots will be across the outer Cape/Nantucket...where northerly flow and some ocean effect clouds should keep overnight low temps in the middle to upper 30s.

Short Term - 6am This Morning Through 6pm Wednesday

Tuesday... High pressure in control will lead to mostly clear skies. Winds will gradually shift to southeast and eventually south as high pressure moves offshore. With 925mb temps 0 to -3C, expect pretty seasonable high temperature readings in the mid to upper 40s. Mix of sun and clouds, perhaps staying mostly cloudy across Cape locations and even eastern MA coast due to ocean effect cloud cover. Overall light winds across the region so overall a very decent day for late November standards.

Tuesday night... As high pressure moves offshore, a very dynamic low pressure system will be moving eastward from the Great Lakes and the Mississippi River valley. This will support a tightening pressure gradient and increasing flow out of the south. This strong southerly flow will advect a warmer and more moist air mass over southern New England. Overnight lows are tricky given that temps will likely fall into the mid 20s to low 30s in the typically cold interior spots. But then during the latter half of the overnight hours, as 925mb low level jet increases to 25 to 30 kt, this will help to moisten the lower levels with 925-850mb RH fields rising to between 50 and 75 percent after midnight. Some mesoscale guidance are hinting at the potential for some light wintry mix across the interior higher elevation where it stays cold enough and where there is just enough moisture in the boundary layer but no good snow growth aloft. Either way, any wintry precipitation will be light and rather transient as warmer air continues to move in towards daybreak.

Long Term - Wednesday Night Through Monday
Highlights

* Strong to damaging winds Wednesday afternoon into Wednesday evening. In addition, rainfall may be heavy at times and impact thepm commute.

* Rain ends Wednesday night, but winds remain strong behind the cold front on Thursday.

* Dry and seasonable on Friday. Strong winds possible along with rain Saturday into Sunday.

Wednesday through Wednesday Night... A slightly negatively tilted trough will be near/just east of the Mid Mississippi River Valley early on Wednesday. This will lift into the Mid Atlantic/eastern Great Lakes by late Wednesday. A warm front will lift into and through much of southern New England on Thursday, while the strong cold front pushes through Wednesday night.

Main concern of this period is the strong to damaging wind gust potential late on Wednesday into Wednesday night. In addition, will see the heaviest rains coinciding with the evening commute. Expect southerly winds to increase throughout the day as the low level jet strengthens. Will see speeds increasing to roughly 40-70 kts at 925 hPa and 40-80 kts at 850 hPa. This is roughly 3-4 STD above normal per the NAEFS wind speed and V-component of the wind late on Wednesday. Do have some uncertainty given the southerly direction with how much of this wind mixes down. Opted to bump up the wind speeds/gusts from the default NBM and just above the NBM90th given Bufkit profiles showing we could tap into winds as high at 40-45 kts. Am a bit concerned that with any heavier rain/showers that move through that we could mix a bit higher. At this point have not hoisted a Wind Advisory as am not confident enough, but suspect it may be needed in a later update. Will note that very late on Wednesday in wake of the cold front am more confident in the gusty winds into Thursday. Still will have 35-50 kts of winds at 850 hPa, which will not be difficult at all to mix down given the strong cold air advection.

Given the strong southerly low level jet pushing in will also see PWATs (Precipitable Waters) approaching roughly 2 STD above normal per the NAEFS guidance as PWATs (Precipitable Waters) approach 1 inch. Fortunately any heavier rain/showers should move through fairly quickly given the progressive nature of the system, but does appear that the heaviest rains would coincide with the Wedpm commute along with the strongest wind gusts. If folks are traveling they may want to allow extra time to reach their destination. Lastly, did bump up temps toward the 75th percentile of guidance to account for the stronger mixing in the boundary layer. This will result in a mild day across the region with highs ranging from the mid 50s to the low 60s.

Thursday through Friday... The negatively tilted trough over the eastern Great Lakes late on Wednesday will lift through much of New England by late Thursday. Behind this trough a shortwave ridge builds in into Friday. The strong cold front will sweep through the rest of the region by late Wednesday night/very early Thursday morning. High pressure will begin to nudge in on Thursday, but really build in/south of the region on Friday.

Main concern through this period is the strong winds persisting through Thursday. Anticipate that any lingering rain/showers tapers off, perhaps as some snow, during the earlyam hours Thursday. Confidence actually is much higher in the strong winds persisting through Thursday than on Wednesday. Will see excellent mixing per Bufkit soundings through the day with W/WNW cold air advection. Will see roughly 35-45 kts of wind at 925 hPa through the day and 35-50 kts of wind at 850 hPa. Should not be very difficult to mix down most of this wind given the cold air advection, but at this point blended toward the NBM90th percentile. Suspect that this is not high enough and wind speeds/gusts will need to be increased further. Not out of the question that any Wind Advisory headlines may need to be extended through Thursday. Will definitely feel much cooler on Thursday as 850 hPa temps decrease to -7 to -10 degrees Celsius. Given this have gone with highs in the 40s on Thursday.

Stuck with the NBM late Thursday through Friday as the pressure gradient relaxes with the high building in. May need to lower temps a bit for Thu night into Friam depending on how quickly the boundary layer decouples. At this point confidence was not high enough to reduce temps from the NBM.

Saturday and Sunday... At this point is looking like a repeat of the Wed-Thu system for Sat into Sunday as another trough lifts into and through the region. This will sweep another cold front through, but given the track it would be all rain until things are winding down. Given the focus on the Wed-Thu timeframe did not spend a whole lot of time on this period and just stuck with the NBM. May need to increase wind speeds/gusts depending on how things evolve in future updates. NAEFS does show a roughly 2-2.5 STD above model climo in wind speed for this timeframe.

Marine
Forecaster Confidence Levels:

Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent.

Overall high confidence. Gale Watches issued for late Wednesday into Thursday evening.

NW winds diminish overnight tonight to below SCA (Small Craft Advisory) thresholds but wave heigheights stay above 5 ft across the southeastern outer waters through Tuesday morning. High pressure builds in across the waters, leading to quiet boating weather for Tuesday into Wednesday morning. Winds increase from the south on Wednesday reaching 35-40 kt with potential for even higher gusts along with rough seas. Therefore, Gale Watches have been hoisted for late Wednesday into Thursday evening for all waters.

Outlook /Wednesday Night through Saturday/... Wednesday: Low risk for gale force winds with gusts up to 35 kt. Areas of rough seas. Rain.

Wednesday Night: Moderate risk for gale force winds with gusts up to 40 kt. Rough seas up to 10 ft. Chance of rain. Local visibility 1 to 3 nm.

Thursday: Strong winds with gusts up to 30 kt. Rough seas up to 9 ft.

Thursday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas.
Friday through Friday Night: Winds less than 25 kt. Seas locally approaching 5 ft.
Saturday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain.

NOAA Boston MA Office: Watches - Warnings - Advisories
CT...None. MA...None. RI...None.

Marine
Small Craft Advisory until 1am EST early this morning for ANZ230>237-251. Gale Watch from Wednesday afternoon through Thursday evening for ANZ230>237-250-251-254>256. Small Craft Advisory until 7am EST this morning for ANZ250- 254>256.