Marine Weather and Tide Forecast for Fall River, MA

NEAR TERM /UNTIL 6 PM THIS EVENING/
Key Messages:

* Fog and stratus disperses around mid to late morning, but lingers over the Cape and Islands most of the day.

* Scattered t-storms possible late in the day (after 3 PM) in western New England, but severe weather is not expected.

Details:

Mild and moist early-morning across Southern New England, with an extensive field of stratus blanketing a large portion of the Northeast. Fog has developed in most locations as well, but so far visibilities have been lowest along the coast, at times as low as one-quarter mile but they've generally been at or around half a mile. Coordinated with NWS New York City on special weather statement for fog through 13z along the South Coast/South Shore, Cape and Islands. Otherwise temps were in the low 60s with similar dewpoints. On the larger scale, we're in a period of midlevel subsidence/weak geopotential height rises, though that stands to change later this afternoon as we start to feel increasing height falls associated with a seasonably strong upper low over the Gt Lakes region.

Probably won't see substantial improvement/scattering of fog and stratus until mid-morning at earliest in western and northern MA into CT, and around late morning to noontime for the Boston to Providence corridor. Given the marine boundary layer, stratus may linger for much of the day along the South Coast, Cape and Islands.

Should be generally dry for most given the subsidence aloft; however some threat for scattered showers and thunderstorms still looks to materialize late in the day (probably not earlier than 3 PM and tending to down-trend by sundown) and mainly west of Fitchburg to Worcester to Willimantic with the onset of geopotential height falls. In what still is best characterized as a weakly-forced setup, the suite of convective-permitting guidance has been all over the place as far as placement goes, but looks like the greatest coverage of storms will be more to our north and west, and we'll have to watch to see if storms can make it over the Berkshires/southern VT. Some instability (around 1000-1200 J/kg) from diurnal heating should be present in western portions of the CWA, but low to midlevel flow is pretty weak and that limits shear magnitudes to less than 30 kt. Given this, probably not seeing much in the way of severe weather potential with this activity but lightning and brief downpours are still threats. Since this activity would stem from last night's round of severe weather in the Gt Lakes region, any smaller- scale impulse from that activity could modify that thinking, and that's something to watch as we move through today, but currently don't see indication of that in obs upstream.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/
Key Messages:

* Fog and stratus develop again tonight, and it may linger for quite a while into Saturday.

* Possible round of scattered t-storms Saturday morning in most areas.

* Better chance at t-storms between 2-8 PM west of Worcester.
Some could become strong.

Details:

Tonight and Saturday:

Any showers or storms in western New England should weaken/dissipate early tonight. We will end up seeing stratus and fog return northward from the waters again tonight.

What will also be taking place in mid and upper levels late tonight and into Saturday is the potent upper low over the Great Lakes will continue to make eastward progress into the eastern part of Michigan. This will induce greater height falls and diffluent flow aloft to overspread much of the Northeast.
Given the moist airmass in place, it won't take much heating or much of a shortwave triggering mechanism at all to get showers and t-storms going. What is also unclear is how today's severe weather setup in the Ohio Valley may influence shower/t-storm coverage or development. There are unfortunately quite a bit of uncertainties as it pertains to thunderstorm potential as we move into Saturday, which is problematic given the number of outdoor events happening, and makes it a difficult call as far as timing and strength of storms goes. The potential exists for a couple rounds of storms, possibly as early as the pre- dawn/early-morning Saturday period in some model solutions; and although this would not likely become strong, it could still be capable of some lightning. There is some loose consensus on a second round of scattered storms during the midafternoon to early evening hours, and it's this second round that may have the better potential for severe weather mainly for interior Southern New England near/west of Worcester. With this second round, low and midlevel flow increases to the point where forecast hodographs become pretty curved in a low-LCL setting, As indicated in the machine-learning progs, potential for locally strong winds and/or a tornado could develop in western MA/CT if storms can root themselves at the surface. That leads to the next source of uncertainty, in that we may still be dealing with quite a bit of stratus and low clouds from the overnight lingering even into the afternoon. The longer those low clouds stick around, the less likely we'll destabilize enough.

Took the approach of keeping thunder probs low in the morning hours, with an isolated mention of thunderstorms. Although I still carry an isolated thunder mention in eastern MA and RI, I opted to instead increase probs for thunder in western MA and CT with the second round of possible storms. Felt uncertainties that I described were too much to include any enhanced wording but that might need to be considered later.

Those with outdoor plans on Saturday will want to keep a close eye to the forecast and monitor for changes.

LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/
Key Messages:

* Cold front moves through Saturday night, drying and cooling the region

* Unsettled weather makes a return later in the week

Details...

Any lingering showers or storms will clear out Saturday night as a cold front passes through southern New England. Generally, the timing for the end of these storms is still somewhat uncertain. Some CAMs are hinting at a line moving through the region after 8 PM, which will be something to monitor. This would depend on how much energy and general instability is left following what moves through in the afternoon/evening, though. Behind the front, drier and cooler conditions with a cold pool settling in aloft that will likely continue into the start of next week. Some scattered showers do remain possible through Sunday as the mid-level low continues its exit offshore into the Gulf of Maine and the cold pool lingers. High temperatures will likely remain in the 60s and low 70s in some spots with less cloud cover Monday, then as the cold pool lingers highs through midweek will likely remain in the 60s.

Some brief mid-level ridging will shift towards southern New England with surface high pressure to start the work week, but the pattern turns unsettled once again towards midweek as another mid-level low over the Great Lakes strengthens and an associated surface low shifts to the northeast from the Ohio River Valley. Some guidance indicates a surface low splitting off from this one in the OH River Valley and moving along the east coast, which could end up impacting southern New England in the form of increased cloud cover and rain chances. However, it is still quite far out in time for any finer details.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

18z TAF Update:

This Afternoon: Moderate confidence.

MVFR-VFR cigs this afternoon. Low chance for an isolated SHRA/TS mainly near and northwest of a BDL-ORH line after 19z ending closer to or just after sundown. Light S winds with more SE seabreeze at BOS.

Tonight: Moderate confidence.

IFR-LIFR ceilings and visibilities return from the coastal waters mainly after 00z. Low chance of an isolated SHRA after 06z.

Saturday: Moderate confidence overall, but lower on timing both sub-VFR improvement and on timing SHRA/TS.

IFR-LIFR stratus likely to begin Sat. Slow improvement late morning through early afternoon with MVFR, improving over the west terminals first then eastward. West terminals improve toward VFR mid afternoon. Lower confidence in timing of further improvements across the east terminals in the afternoon, likely not until late afternoon if it does scatter out. Convective showers/storms possible in the morning 13-16z, but will be isolated- widely scattered. Another round for western airports after 18z and closer to 00z. Timing lower confidence. Some storms could become strong, with a better chance for strong activity in the 2nd round of storms for BAF- BDL- ORH. Winds mainly SE to S around 5-10 kt.

KBOS TAF...Moderate confidence. Seabreeze til 23z. IFR cigs move in after 00z with lowering visibilities from BR. Slow improvements in ceilings Saturday morning with MVFR cigs. Low chance for convective showers 14-16z around the terminal. SE winds 5-12 kts.

KBDL TAF...Moderate confidence. ISO SHRA/TS through 00z.
IFR/LIFR overnight. Gradual improvements after 15z toward MVFR and VFR later in afternoon. Few rounds of thunderstorms possible in the afternoon and early evening. Timing lower confidence. Few stronger storms possible, more likely with the early evening round of storms.

Outlook /Saturday Night through Wednesday/...

Saturday Night: VFR. Chance SHRA.

Sunday through Sunday Night: Mainly VFR, with local MVFR possible. Breezy. Slight chance SHRA.

Monday through Tuesday: VFR. Breezy.

Tuesday Night: VFR. Slight chance SHRA.

Wednesday: Chance SHRA.

MARINE
Forecaster Confidence Levels:

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

High confidence overall.

Expect sub-SCA conditions to prevail on the waters. Fog and reduced visibility will be the biggest potential hazard for mariners today and tonight, with S winds around 10 kt and seas 4 ft or less. Risk for thunderstorms could develop as soon as pre-dawn Saturday over the southern waters, with another round of storms possible into Saturday afternoon.

Outlook /Saturday Night through Wednesday/...

Saturday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, isolated thunderstorms.

Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft.

Sunday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Slight chance of rain showers.

Monday: Winds less than 25 kt. Areas of seas approaching 5 ft.

Monday Night through Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft.

Tuesday Night: Winds less than 25 kt.

Wednesday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain showers.

BOX WATCHES/WARNINGS/ADVISORIES
CT...None.
MA...None.
RI...None.
MARINE...None.