textproduct: Boston / Norton

WHAT HAS CHANGED

Forecast remains on track.

KEY MESSAGES

- Above normal temperatures and humidity continues through Tuesday. Relief from the heat & humidity comes late week.

- Unsettled weather continues this week with shower and thunderstorms chances returning this evening as well as Wednesday night/Thursday morning.

DISCUSSION

KEY MESSAGE 1...Above normal temperatures and humidity continues through Tuesday. Relief from the heat & humidity arrives for the weekend.

After a brief respite from the humidity this morning, dewpoints will start climbing back into the upper 60s to low 70s once the sun comes up. Temperatures should be a tad cooler today.... roughly 85-89 instead of the 90+ we've been seeing lately. Humidity will linger through Tuesday, but both temperatures and dewpoints will slowly begin to trend lower throughout the week, bringing much needed relief to southern New England by Friday. High temps heading into the weekend likely near 80 with dewpoints dropping into the 50s, possibly even the 40s in the higher elevations.

KEY MESSAGE 2...Unsettled weather continues this week with shower and thunderstorms chances returning this evening as well as Wednesday night/Thursday morning.

A passing cold pool across northern New England should help to generate CAPE values of 750-1,250 J/kg by late this afternoon. Combined with a one-two punch from a passing warm front and trough axis moving through southern New England, some scattered showers and thunderstorms could pop later this evening. CAM guidance is once again struggling to resolve these storms, with some models indicating storms over NW MA, others show W CT, and others still keep storms confined to the Albany/NYC metro regions. Confidence is on the lower end as far as timing and placement, but currently thinking late afternoon into the sunset hours with highest chances for a strong to severe storm forming along the CT River Valley. A few showers could stray as far east as the ORH-PVD corridor; however, if these showers move that far east, they should be sub- severe.

Tuesday and Wednesday should remain dry and mostly sunny, pleasant days. But by Wednesday night/Thursday morning, a low pressure system sitting over the Hudson Bay will be pushing south/southeast into southern Quebec and New England. A few associated upper-level shortwaves and a cold front will likely be the catalyst for another round of thunderstorm chances; however, the main limiting factor will be the time of day the front pushes through. If the front hits the eastern MA coast by early Thursday afternoon, we'd expect weaker instability and a lower thunderstorm risk. However, if the front stalls or moves slower, then the risk for storms would increase, and so would the chance for any one storm to reach severe levels.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Forecaster Confidence Levels...

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

12z TAF Update:

Today: Generally high confidence, but moderate confidence on timing/probability of TSRA.

Mainly VFR; hazy-looking skies from smoke possible. Light N winds flip to SW by the afternoon 5-10 kts. Sea breeze likely at BOS 13-15Z out of the ESE around 10 kts. Sea breeze possible at PVD late morning through first half of afternoon with SSE winds.

SHRA/TSRA look to develop late in the day, starting as soon as 21z at BDL with the higher risk after 23Z. Confidence decreases in TSRA as the activity moves E/ESE toward ORH and further east terminals (00-05Z). Given the isolated nature, kept as VCTS for BDL. Lower probabilities and confidence have kept mention of TSRA out of the terminals east of BDL at this time.

Toight: High confidence.

VFR. Sea breeze at BOS kicks out 23-01Z with winds shifting to SW. SW winds 5-10 kts shift to WSW/W overnight.

KBOS Terminal...Moderate confidence in TAF. Generally VFR. Wildfire smoke may be visible aloft today. Seabreeze likely to develop between 14-15z, earliest 13Z. Reduced confidence on when it will kick back SW, but more likely in the 23-01Z timeframe. Low probability for a SHRA/TSRA after 01-06Z. Too low to include in TAF at this time.

KBDL Terminal...Moderate confidence in TAF. Wildfire smoke aloft possible. Potential for scattered SHRA or a TSRA after 21z, but moreso after 23Z. If any storms develop, a stronger storm is possible with gusty winds, frequent lighting, and brief IFR visbys.

Outlook /Tuesday Night through Friday/...

Tuesday Night through Wednesday: VFR.

Wednesday Night: VFR. Chance SHRA.

Thursday: VFR. Breezy. Chance SHRA, slight chance TSRA.

Thursday Night: VFR. Slight chance SHRA.

Friday: VFR. Breezy.

MARINE

Forecaster Confidence Levels...

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

Through Tuesday... High Confidence.

Winds return to SW this morning. Local sea breezes along the east coast of MA. Relatively light seas across the waters through tonight. Could see some breezy winds near 20kts later this evening into Tuesday morning.

Outlook /Tuesday Night through Friday/...

Tuesday Night through Wednesday Night: Winds less than 25 kt.

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers, slight chance of thunderstorms.

Thursday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers.

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

BOX WATCHES/WARNINGS/ADVISORIES

CT...None. MA...None. RI...None. MARINE...None.