Marine Weather and Tide Forecast for Plymouth, MA

NEAR TERM /UNTIL 6 PM THIS EVENING/
315 AM Update:

Key Messages:

* Foggy, misty overcast this morning; overcast much of today but some decrease in clouds late.

* Light rain showers with cold front passage mid morning to mid afternoon from west to east. Additional spotty precip in the Berks could be cold enough for brief snowflakes late this afternoon.

* Current temps upper 40s to upper 50s are today's highs, with not much net change in temps, but will be falling by sundown in the Berkshires.

Details:

By mid-November standards, it's an anomalously mild early morning across Southern New England, as a subtropical feed of moisture is being advected northward in deep SSW flow aloft across the Northeast. This is ahead of an impressive upper level low centered in the vicinity of Chicago, associated with an early-season outbreak of winter-like air which extends into the Deep South! Current temps in Southern New England are in the 50s, with some upper 50s/near 60 in southeast New England. By comparison, as of this AFD, Atlanta GA is 40 degrees with a NW wind gusting to 35 knots. We are also socked in with low-level moisture trapped beneath a dry punch of air in midlevels, and is contributing pretty widespread mist, fog and at times some areas of drizzle. We've issued an SPS for foggy conditions through 5 AM to address any travel difficulties, as reduced visbys (generally half to 4 miles, but could be as low as quarter mile in spots) are likely to persist into part of the morning.

Looking likely we'll remain in this dreary overcast for some time today. But a strong cold front is right on our doorstep, producing a shield of light to moderate rain showers from the Hudson Valley on southward into NJ. Some improvement to visbys is expected as the front and rain showers overspread; it's a messy frontal passage, but a best estimate on arrival of rain showers is around 4-7 AM in far western New England and the Berkshires, around 10-noontime in central MA, into eastern MA and RI around noon to 2 PM and making it offshore by sundown.
Should see cloud cover then start to scatter and lift but today's a generally mostly cloudy to overcast day. There may be additional light precip behind the cold front in interior western New England into the afternoon, which could include some backside light snow showers later in the day into the western hilltowns of the Berkshires but these would be more novel/decorative than causing impacts as the colder air starts to work its way in.

After the cold front moves through, the truly cold air will only gradually ooze in. Highs for the day have already occurred or are occurring, but temperatures most of today won't really change all that much, until we get to late this afternoon in the Berkshires. So we should see temperatures today in the 50s. But the bottom will be falling out with the temperatures after sundown in all areas, with the first real taste of winter-like temperatures arriving tonight and especially Tuesday.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/
315 AM Update:

Key Messages:

* Winterlike temps arrive tonight: upper 30s to low-mid 50s early tonight crash to widespread subfreezing readings by dawn.

* Partly cloudy Tue, but with below normal temps and gusty NW winds producing a biting cold. Highs in the 30s (sub-freezing highs in the terrain), but will feel like the mid teens to the 20s in most areas, with NW gusts 30-40 mph.

* Intervals of snow showers in the terrain Tue afternoon, but nil accumulation.

Details:

Tonight:

Surge of strong low-level cold advection takes place tonight, to go along with rapid drying and increasing WNW winds. 925 mb temps start out around -2 to 0C in the Berkshires, and around +2 to +10C elsewhere, warmer east. By morning, 925 mb temps in all areas are in the -5 to -7C range. Starting tonight in the mid 30s in the Berkshires to the 40s central sections to lower 50s near the coast. By midnight, much of the interior will be in the mid 20s to around freezing, and turns to widespread subfreezing temps to the coast by dawn.

Westerly winds will accompany this surge in colder air, and we should see wind chills between 4 and 7 AM in the mid to upper teens in the terrain, and the low to mid 20s for the lower elevations and coastal plain, and around freezing for the Cape and Islands.

Tuesday / Veterans Day:

The cold upper trough gradually lifts out toward the ENE through the day. This will allow for an enhanced westerly flow with partly to mostly cloudy skies (more clouds toward the west due to advection of Great Lakes-enhanced moisture). The anomalously cold air will steepen lapse rates considerably, with potential for mixing depths up to 800 mb.

The net result for Tue is anomalously cold daytime temperatures with gusty northwest winds making for a biting cold. Ambient air temps only rise a few degrees, with ineffective warming from partial sun offset by the cold air, leading to high temps in the upper 20s/around freezing for the terrain, and the mid to upper 30s for most of Southern New England (around 40 near the south coast, Cape and Islands). Mixed-layer speeds at the top of the deep boundary layer are as high as 45 kt, so gusts in the 30 to 40 mph range are conceivable with sustained west winds around 15-20 mph. Wind chills in most areas are in the 20s, with mid to upper teens in the terrain! Add a couple layers for this winterlike chill if you're headed outside.

Weak lift in a saturated dendrite growth layer out in the Berkshires and into the MA portion of CT Valley Tue aftn could result in periodic, unfocused snow showers, given Froude numbers around 1 to 2 favoring unblocked terrain flow. But even with the cold air, pavement temps are still too warm for any impacts, so more likely to be decorative at worst.

LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/
Key Messages...

* Cold and blustery Tuesday night.

* A few rain and elevation snow showers possible Wednesday.

* Increasingly dry with a moderating trend in temps through the late week period.

Another cold night Tuesday night for much of the CWA Lows will moderate compared to Monday night owing to a well mixed boundary layer and increasing mid and high clouds. Temperatures Tuesday night fall into the upper 20s in the terrain and the middle to lower 30s for other areas.

Recent runs of CAMs have come in quite a bit more amplified with a shortwave rotating through the region on Wednesday. The result should be greater coverage of precipitation and cloud cover for much of the day. Expecting a warmer day as the flow becomes southerly.
Highs will likely climb to near 50 near the coast but may be quite a struggle to get out of the 30s in the higher terrain. Elevated areas may see snow scattered showers through Wednesday afternoon with plenty of moisture and forcing.

We'll feel the influence of a lingering trough over the northeast through the rest of the workweek keeping temperatures cooler than average generally in the upper 40s. A few weak disturbances round the trough leading mainly to some orographic rain/snow showers and ocean effect showers offshore, but the column remains largely dry which should prevent any widespread precipitation for the week and into the weekend as a brief ridge approaches around the weekend.

AVIATION /08Z MONDAY THROUGH FRIDAY/
Forecaster Confidence Levels...

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

06Z TAF Update:

Tonight: High confidence in trends but moderate on timing.

Continued IFR-LIFR ceilings with FG/BR and -DZ. Winds turn toward SE/S overnight possibly becoming light and variable through the early morning.

Monday: Moderate confidence.

IFR-LIFR to start. Another batch of rain moves through ahead of the cold front generally from west to east. Rain likely arrives 10-12z across the western terminals and closer to 14-16 further east. Frontal passage 15-22z with ceilings quickly improving behind it. Windshift to W around 10-12 kt with frontal passage.

KBOS Terminal...Moderate confidence in TAF.
IFR/LIFR conditions through the rest of the night into the morning hours. Another round of showers with slight improvements in ceilings arrive 14-16z Monday. FROPA 20-22z with ceilings improving to MVFR behind it.

KBDL Terminal...Moderate confidence in TAF.

Outlook /Tuesday Night through Friday/...

Tuesday Night: VFR. Windy with gusts up to 35 kt.

Wednesday: Mainly VFR, with local MVFR possible. Windy with local gusts up to 30 kt. Slight chance RA.

Wednesday Night through Thursday: Mainly VFR, with local MVFR possible. Breezy.

Thursday Night through Friday: VFR. Breezy.

MARINE
Forecaster Confidence Levels...

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

Key Messages:

* SCAs still valid thru 12z Tue, but these are for seas in the 5-7 ft range which will be slow to subside.

* Foggy conditions especially this morning reduce visby, with periods of rain by mid-morning, clearing late afternoon.

* Gale force westerly gusts on all waters Tue into part of Wed.
Gale Warnings in effect for Tue into early Wed.

Seas are still elevated this morning and will only slowly subside through tonight. Therefore SCAs were extended through Monday night. Light winds this morning to gradually become W with an increase in speeds to around 10-15 kt with gusts 20 kt late this afternoon and tonight, as a cold front crosses the waters.

An anomalously cold airmass over the waters with a strong WNW pressure gradient will allow for gale force gusts to then develop by Tuesday and linger into at least part of the first half of Wednesday. Given high confidence, Gale Watches have been converted to Gale Warnings on all waters for this Tue- Wed period. Gusts 35-40 kt are expected with seas building to around 12-14 ft over the offshore waters.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Strong winds with gusts up to 40 kt. Rough seas up to 14 ft.

Wednesday: Strong winds with gusts up to 35 kt. Rough seas up to 13 ft. Chance of rain.

Wednesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Slight chance of rain.

Thursday: Moderate risk for Small Craft Advisory winds with areas of gusts up to 30 kt. Areas of rough seas. Slight chance of rain.

Thursday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Slight chance of rain.

Friday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Slight chance of rain.

BOX WATCHES/WARNINGS/ADVISORIES
CT...None.
MA...None.
RI...None.
MARINE...Gale Warning from 7 AM Tuesday to 7 AM EST Wednesday for ANZ230-236.
Small Craft Advisory until 1 PM EST this afternoon for ANZ231- 251.
Gale Warning from 7 AM Tuesday to 1 PM EST Wednesday for ANZ231>235-237-250-251-254>256.
Small Craft Advisory until 7 AM EST Tuesday for ANZ235-237-250- 254>256.