Old Res Weather

Lexington, Massachusetts, USA

35°F

2/16/2025 7:17pm

Lexington Conditions: Clear
Temperature: 35.1°F / 1.7°C
Dew Point: 32.4°F
Relative Humidity: 90%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.00 in Falling Slowly
Visibility: 10 miles
Rain Today: 0.01 in
UV Index: $VPuv None

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 041859
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
259 PM EDT Tue Aug 4 2026

.WHAT HAS CHANGED...
Confidence continues to increase for the region to see a stretch
of warm and humid conditions for late week into the weekend. 

&&

.KEY MESSAGES...

- Weak low pressure brings some clouds and a low risk for a 
  shower early Wednesday across Martha's Vineyard and Nantucket

- Increasing heat and humidity across much of southern New
  England, along with daily afternoon pop-up thunderstorms from
  Thursday through this weekend. A widespread washout is not
  anticipated at this time.

&&

.DISCUSSION...
KEY MESSAGE 1...Weak low pressure brings some clouds and a low 
risk for a shower early Wednesday across Martha's Vineyard and 
Nantucket

Overall a pretty quiet night, weather-wise, is expected for most
of the region. Weak high pressure over CT and western MA will
result in mostly clear skies with some patchy valley fog perhaps
forming. Low temperatures will be seasonable, generally the
lower 60s. The only other feature on the weather map is a very 
weak low pressure several hundred miles of southern New England.
This will track northeast, and although it will pass south of 
Nantucket late tonite/early Wednesday morning, moisture around 
the low may be enough to produce a period of low clouds as far 
north as Cape Cod. Low (less than 25%) chance of a light shower 
is also possible across Martha's Vineyard and Nantucket between 
roughly 4a-8a. 

KEY MESSAGE 2...Increasing heat and humidity across much of southern 
New England, along with daily afternoon pop-up thunderstorms 
from Thursday through this weekend. A widespread washout is not 
anticipated at this time.

There is increasing confidence in a prolonged period of midsummer 
warmth and humidity, along with daily chances for afternoon pop-up 
thunderstorms from Thursday through the upcoming weekend. However, a 
widespread washout is not anticipated. Given the abundant rainfall 
earlier this week, any storms capable of producing heavy downpours 
could lead to localized instances of flash flooding. This is 
reflected in the WPC Marginal Risk (Level 1 of 4) for excessive 
rainfall across western New England on Thursday and all of southern 
New England on Friday. 

Bermuda high pressure develops this week and remains anchored over 
the western Atlantic through the remainder of the forecast period. 
With persistent southwesterly flow, expect above-normal temperatures 
along with increasing humidity. While temperatures will be above 
climatological normals, they are not particularly unusual for early 
August. High temperatures from Thursday through Sunday should climb 
well into the upper 80s and lower 90s, while dewpoints rise into the 
lower to middle 70s. This combination will result in heat index 
values of 95 to 100 degrees. If current trends continue, Heat 
Advisories may be needed for portions of the region Thursday and 
Friday, and perhaps Saturday as well. One uncertainty is the degree 
of afternoon cloud cover and thunderstorm development, which could 
temper temperatures somewhat. This will be monitored over the coming 
days.

Regarding thunderstorm chances, the overall synoptic pattern 
features the Bermuda High over the western Atlantic with a mid-level 
ridge extending across the Northeast. Embedded shortwave 
disturbances riding through the flow should provide enough lift to 
initiate scattered afternoon and evening thunderstorms from Thursday 
through Sunday. Although deep-layer shear remains weak, instability 
will be plentiful, with forecast CAPE values generally between 1,500 
and 2,000 J/kg. As a result, storms should remain largely pulse-type 
and disorganized rather than organized severe convection. BUFKIT 
soundings depict tall, skinny CAPE profiles, suggesting efficient 
warm-rain processes and the potential for locally heavy rainfall. 
PWAT values around 1.7 inches further support the threat of 
torrential downpours. In addition to localized flooding, gusty winds 
and frequent lightning will be the primary hazards.

That said, not every community will experience thunderstorms each 
day. Many locations will remain dry, so there is no reason to cancel 
outdoor plans at this point. The details regarding storm coverage 
and placement will become clearer once the convection-allowing 
guidance comes into range over the next couple of days.


&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...

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

18z TAF Update:

High Confidence. 

Currently VFR area wide with light west winds to about 10kt.
There is a weak sea breeze along the coast south of Boston. That
sea breeze will fade prior to sunset. Weak high pressure
overhead tonight will result in generally clear skies and light
winds for most of the region. Could see some patchy valley fog,
but not expecting any at TAF locations. Slightly different
outlook for the Cape and Islands. Weak low pressure will pass
south of ACK late tonight, but could be close enough to result
in some lower ceilings. Have some MVFR for FMH and HYA, and IFR
at ACK. Could even see -SHRA at ACK early in the morning. Any
low ceilings should clear out by 14z.  

Otherwise Wednesday will feature VFR. Believe a sea breeze will
again form. Although an isolated shower can't be ruled out
across the western interior. Increasing moisture Wednesday night
should result in MVFR/IFR conditions as low clouds, especially
across the southern coastal areas. May also see a few -SHRA
develop prior to 12z Thursday across CT. 

KBOS Terminal...High confidence in TAF. Sea breeze today is
expected to stay just east of the airport, but could make a
quick visit prior to 22z. 

KBDL Terminal...High confidence in TAF. Winds may be a bit
variable this afternoon before settling into a more southerly
wind direction. 

Outlook /Thursday through Sunday/...

Thursday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA, chance TSRA.

Thursday Night: VFR. 

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

Friday Night: VFR. Slight chance SHRA, slight chance TSRA.

Saturday: VFR. Breezy. Chance SHRA, chance TSRA.

Saturday Night through Sunday: VFR. Breezy. 

&&

.MARINE...
Forecaster Confidence Levels...

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

The need for a Small Craft Advisory across the outer southern
waters will come to an end by early this evening as seas slowly
subside to below 5ft. Otherwise a "Bermuda High" will become
firmly entrenched off the eastern sea board resulting in an
extended period of SW winds. 

Outlook /Thursday through Sunday/...

Thursday: Winds less than 25 kt. 

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

Friday: Winds less than 25 kt. 

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

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

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

Sunday: Winds less than 25 kt. 

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Risk for Rip Currents until 9 PM EDT this evening for MAZ020-
     023-024.
RI...High Risk for Rip Currents until 9 PM EDT this evening for 
     RIZ006>008.
MARINE...Small Craft Advisory until 8 PM EDT this evening for ANZ255-
     256.

&&

$$

DISCUSSION...Dooley/Nash
AVIATION...Dooley/Nash
MARINE...Dooley/Nash