Marine Weather and Tide Forecast for Plymouth, MA

NEAR TERM /UNTIL 6 AM FRIDAY MORNING/
Key Messages:

* Heat Advisory in effect through 8PM with apparent temps near triple digits

* Severe thunderstorm risk quickly wanes

Details:

Heat and Humidity...

A Heat Advisory remains in effect through 8 PM this evening. We've already seen several hours of full sun today, and the temperatures skyrocketed this morning in response. Expecting temperatures to continue to warm into the lower to mid 90s, and with dewpoint temperatures in the low to mid 70s, it may feel closer to the low 100s.

Remember to stay hydrated and limit strenuous outdoor activities today. Take frequent breaks in locations with air conditioning and wear light weight and light colored clothing.

Strong to Severe Thunderstorms This Afternoon...

The severe threat has quickly waned as earlier convection made quick work of instability. As a result, the severe thunderstorm watch has been cancelled.



SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/
Key Messages:

* Sunny and slightly cooler Friday

* High winds likely during the day on Friday

Friday and Friday Night:

Clearing skies and lots of sun combine with a low-level jet around 40 kts and lead to the likelihood of quite high winds at the surface.
Thinking we could see areas of 30-45 mph with a few gusts near 50 mph in parts of western, central, and northeastern Massachusetts and possibly go with a Wind Advisory for Friday.
Already went with a Gale Warning for Boston Harbor, Massachusetts Bay, and Ipswich bay for the day. Wind speeds should decrease more steadily into Friday evening.

We'll start to dry out a little bit for the start of the weekend once the post-FROPA airmass moves in. Temperatures look to be in the mid 80s across the interior and mid to upper 70s across the Cape and Islands.

LONG TERM /SATURDAY THROUGH THURSDAY/
Key Messages:

* More seasonable temperatures for the weekend behind cold front.

* Slight chance for showers and thunderstorms early Saturday but coverage is in question.

* Multiple days of dangerous heat still expected through mid-week next week. Air temperatures could rise as high as 100 degrees with humidity making things feel even hotter. Greatest chance across the interior, especially in river valleys and urban areas.

Little in the way of changes with regards to the evolution of the upper-level pattern in the 3-7 day range. Heights are still expected to build across the eastern CONUS as a trough deepens over the western CONUS. This results in a strong ridge centered over the Ohio Valley and Mid Atlantic. Ensemble guidance suggests that 500 millibar heights rise to as high as 597 dm by Tuesday. This setup likely brings the hottest conditions of the season so far starting Monday and lasting through Wednesday. Widespread 90's, and even a few 100-degree readings will be likely across the region. Locally hotter conditions are possible in river valleys where downslope flow may warm things by a few degrees.

Saturday and Sunday:

The warm-up begins Saturday as heights start to build over the region. Temperatures will be near to slightly above normal with highs rising into the mid and upper 80s except across the Cape and Islands where southwesterly flow will likely keep things a bit cooler. High temperatures climb a bit more on Sunday, likely reaching the upper 80s and lower 90s across the interior.

Outside of the increasing temperatures, there is a slight chance for a few showers or thunderstorms earlier Saturday. A weak shortwave moving around the periphery of the building ridge may bring a round of showers and storms mainly across northwestern areas. At the moment the risk is quite low as the storms will be battling rising heights and limited surface instability.

Through Mid-Week:

Confidence in a significant heat event continues as guidance shows near unanimous agreement in dangerously hot conditions. Heat starts to build on Monday with ensemble guidance showing probs near 100 percent for high temperatures >90F across much of the interior. The NBM suggests even hotter conditions on Tuesday with widespread 90- 95% probs of high temperatures exceeding 95F! A few spots in area river valleys may approach 100 degrees with light westerly downslope flow. The idea for widespread heat is further supported by 850mb temperatures soaring to +22-24C Monday and Tuesday! This is an impressive signal considering we are still more than 120 hours away from the event. Some relief is possible Wednesday as low pressure passing through the Canadian Maritimes swings a weak backdoor cold front through the area. Guidance suggests than an onshore flow develops by Wednesday afternoon. The onshore flow could bring a relief from the hot weather, mainly for coastal areas and much of eastern MA.

AVIATION /00Z FRIDAY THROUGH TUESDAY/
Forecaster Confidence Levels...

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

00Z TAF Update:

Tonight: High confidence.

A low chance for lingering TSRA thru 02z but improvement is expected at all airports. IFR stratus and fog out over the Cape and Islands may still linger until we see a gusty westerly windshift overnight. SW to W winds increase to around 10-15 kt with gusts low-20s kt range and LLWS for the Cape and Islands from a 40kt westerly low level jet.

Friday: High confidence.

VFR. W/WNW winds become gusty by late morning, with speeds 13-18 kt and gusts 25-35 kt.

KBOS Terminal...High confidence in TAF.

VFR ceilings with the main concern being gusty west winds. Winds overnight switch to 240 between 12 and 15 kt. Stronger winds arrive around 15z Friday with frequent gusts up to 35 kt. Winds quickly calm tomorrow night.

KBDL Terminal...High confidence in TAF.

IFR VFR ceilings S winds around 10-12 kt with gusts to 20 kt this evening, then with a windshift to W around midnight at similar speeds. Increasing winds tomorrow with gusts around 35 kt around 15z. Winds slowly calm throughout the afternoon tomorrow.

Outlook /Saturday through Tuesday/...

Saturday: VFR.

Saturday Night through Sunday: Mainly VFR, with areas MVFR possible. Breezy. Slight chance SHRA, slight chance TSRA.

Sunday Night: VFR. Breezy.

Monday through Monday Night: VFR.

Tuesday:

MARINE
Forecaster Confidence Levels...

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

Small craft advisories have been expanded to all waters starting this afternoon and were also extended into Friday. SW gusts today should reach into the 25 kt range, although we expect stronger gusts on Friday on all waters to around 30 kt. Gusts could approach near gale force at times on Friday. Seas will also be building today to around 3-5 ft, and then increase to around 4-7 ft on Friday.

Because of the building seas and SW to W winds expected for today and tonight, we've also hoisted a rip current statement for today and Friday on south-facing beaches. It is somewhat borderline today, but the threat for dangerous rip currents should increase tonight and into Friday.

Outlook /Saturday through Tuesday/...

Saturday: Winds less than 25 kt.

Saturday Night: Winds less than 25 kt. Slight chance of rain showers.

Sunday: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers.

Sunday Night through Tuesday: Winds less than 25 kt.

BOX WATCHES/WARNINGS/ADVISORIES
CT...Heat Advisory until 8 PM EDT this evening for CTZ002>004.
MA...Heat Advisory until 8 PM EDT this evening for MAZ003>007- 010>019-026.
High Risk for Rip Currents through Friday evening for MAZ023-024.
RI...Heat Advisory until 8 PM EDT this evening for RIZ001-002.
High Risk for Rip Currents through Friday evening for RIZ008.
MARINE...Gale Warning from 9 AM to 7 PM EDT Friday for ANZ230-251.
Small Craft Advisory until 8 PM EDT Friday for ANZ231>237-250- 254>256.