textproduct: Boston / Norton

WHAT HAS CHANGED

A Heat Advisory has been issued Tuesday into Wednesday for much of southern New England. Heat Indices are likely to reach 100-103 in some areas.

KEY MESSAGES

- Dry and comfortable conditions continue today.

- Heat and humidity return midweek. Heat Advisories go into effect Tuesday morning through Wednesday evening.

- Periods of unsettled weather possible later this week as an upper level trough pushes over the region.

DISCUSSION

KEY MESSAGE 1...Dry and comfortable conditions continue today.

Broad high pressure continue to sit of New England today, pushing offshore later tonight. Some low-end PoPs across northern and western MA have been included due to the passage of a weak shortwave trough later this afternoon, but any showers will be scattered and sub-severe in nature. Otherwise, most areas will remain dry through the day, and south-southwesterly flow will allow for temperatures in the mid to uppers 80s with heat indices in the upper 80s to low 90s.

KEY MESSAGE 2...Heat and humidity return midweek. Heat Advisories go into effect Tuesday morning through Wednesday evening.

Broad mid-level high pressure over the Upper Midwest Tuesday with ridging extending all the way out to New England will bring a period of rising heat through Wednesday. 850mb temperatures rise to near +23C by Tuesday evening, allowing for surface temperatures to soar into the mid 90s across southern New England both Tuesday and Wednesday. Prolonged southwesterly flow will also surge dewpoints to near 70. Combined with poor overnight relief Tuesday night with low temperatures likely remaining in the mid 70s to near 80 in some areas, Heat Advisories have been issued across most of southern New England (excluding the Cape/Islands and eastern slopes of the Berkshires) for Tuesday morning through Wednesday evening. While not as intense as the previous stretch of hot weather, temperatures of this magnitude will still present significant risks for those working or doing recreation outdoors.

KEY MESSAGE 3...Periods of unsettled weather possible later this week as an upper level trough pushes over the region.

Ensemble guidance continues to indicate an amplifying upper- level trough across Quebec later on in the week, allowing cooler 850mb temps around +10C to +13C to prevail. This will help cool surface temperature to the low to mid 80s by Friday (upper 80s across the CT River Valley). Several weak shortwaves pushing through with the trough bring chances for precipitation and unsettled weather by the end of the week and into 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.

Through Tuesday Morning: High Confidence.

VFR. Increasing southwesterly winds today, with some gusts near 20 kts possible this afternoon. SCT mid-level cloud deck likely later this afternoon into the overnight hours. LLWS possible for a few hours across the SE MA terminals, including BOS, later tonight after 00z. Southwesterly winds drop to 10 kts or less after midnight.

KBOS Terminal...High Confidence.

KBDL Terminal...High confidence.

Outlook /Tuesday through Friday/...

Tuesday: VFR. Windy with areas of gusts up to 30 kt.

Tuesday Night: VFR. Windy with local gusts up to 30 kt.

Wednesday: VFR. Breezy.

Wednesday Night: VFR.

Thursday through Thursday Night: VFR. Breezy.

Friday: VFR.

MARINE

Forecaster Confidence Levels...

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

Through Tuesday...High confidence.

High pressure moves offshore later today with southwest winds increasing across the coastal waters. SCA have been issued Tuesday, with gusty southwest winds 25-30 kts across the southern and eastern waters. Seas will be quite choppy Tuesday into Wednesday morning as well, with wave heights 5-8 ft possible across the southern ocean waters and 3-5 ft along the coastal waters, including Vineyard and Nantucket Sounds.

Outlook /Tuesday through Friday/...

Tuesday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Seas up to 5 ft.

Tuesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 9 ft.

Wednesday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas.

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

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.

Thursday Night through Friday: Winds less than 25 kt.

BOX WATCHES/WARNINGS/ADVISORIES

CT...Heat Advisory from 11 AM Tuesday to 8 PM EDT Wednesday for CTZ002>004. MA...Heat Advisory from 11 AM Tuesday to 8 PM EDT Wednesday for MAZ003>007-010>021-026. RI...Heat Advisory from 11 AM Tuesday to 8 PM EDT Wednesday for RIZ001>007. MARINE...Small Craft Advisory from 4 PM to 11 PM EDT Tuesday for ANZ231- 250. Small Craft Advisory from noon Tuesday to 11 AM EDT Wednesday for ANZ232-233-235-237-254>256. Small Craft Advisory from noon Tuesday to 5 AM EDT Wednesday for ANZ234.