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 061231
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
831 AM EDT Thu Aug 6 2026

.WHAT HAS CHANGED...
Forecast remains on track. Heat Advisories remain in effect 
from 11 AM today through 8 PM Friday for most of southern New 
England (excluding the eastern slopes, Cape, and Islands).

&&

.KEY MESSAGES...

- Heat and humidity climb to Advisory level today and
  lingers through Friday, possibly into the weekend.

- Diurnal pop-up thunderstorms remain a daily threat, but are 
  most likely Saturday, with a lower chance on Sunday. Unsettled
  weather may return early next week, as well as continuing 
  high humidity.

&&

.DISCUSSION...
KEY MESSAGE 1...Heat and humidity climb to Advisory level today and 
lingers through Friday, possibly into the weekend.

A Bermuda high begins to build in across the western Atlantic Ocean 
and southerly flow continues today. Temperatures and dew points have 
already begun to rise: T of 73 (up from 69 just before midnight) and 
Td of 71 (up from 67). They'll only continue to surge throughout the 
day and again on Friday, with temperatures likely topping out near 
90 and oppressive dew points near 75, leading to "feels like" 
temperatures climbing into the mid to upper 90s... possibly even 
near 100 at times. Greatest risk of heat indicies reaching triple 
digits remains in the CT and Merrimack River Valleys where localized 
downslope winds could help boost temperatures. Some uncertainty 
remains regarding the magnitude of heat elsewhere due to the chance 
for increasing cloud cover from any thunderstorms that develop today 
and Friday afternoons. Expecting poor overnight relief heading into 
Friday with nighttime temperatures hovering 71-73 as well as 
dewpoints struggling to drop to 70... tonight's heat indicies are 
likely to hover 77-80. The warm overnight temperatures will be 
dangerous for those without adequate access to cooling, especially 
in urban areas. 

A Heat Advisory remains in effect from 11 AM today through 8 PM 
Friday, and future shifts may need to extend the Advisory into 
Saturday if the heat persists.

KEY MESSAGE 2...Diurnal pop-up thunderstorms remain a daily threat, 
but are most likely Saturday, with a lower chance on Sunday. 
Unsettled weather may return early next week, as well as continuing 
high humidity.

A few weak, upper level disturbances passing through New England 
combining with the high heat/humidity and just enough instability 
will likely be enough to pop a few diurnal showers/thunderstorms 
each day through the weekend, with greatest chances Saturday. While 
the potential for storms to be severe is on the lower end, any 
thunderstorms that do pop have the potential to produce frequent 
lightning, gusty winds, and torrential downpours as PWATs will 
likely be around 2.0". Model soundings also indicate the mid-level 
steering flow could be rather week, leading to slow moving storms or 
even training. Given the amount of rain southern New England has 
seen over the last week or so, any heavy downpours could lead to 
localized flooding.

Expecting a few more shortwaves to move through the upper-level flow 
as well as a trailing cold front early next week, bringing 
additional chances for showers to southern New England Monday night 
into Tuesday. The FROPA could bring a small amount of relief from 
the heat for the start of the next work week, but humidity levels 
likely will remain elevated through mid-week.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
Forecaster Confidence Levels...

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

12z Update:

Today...Moderate Confidence (cigs, TSRA chances)

MVFR/IFR CIGS this morning slowly improving to VFR between
14-16Z for most terminals. Slower trend for Cape/Islands with
imrovements closer to 17-19Z. SW winds 8-12 kts, gusting up to 
20 kts this afternoon for Cape/Islands. Low probability for a
sea breeze at BOS early afternoon. 

Low chances for an isolated afternoon SHRA or TSRA across 
western areas of southern New England. Have opted to include a 
PROB30 for TSRA at KBDL after 20z today as they have a higher
probability of a storm developing nearby.

Tonight into Friday...Moderate confidence. 

VFR with potential for MVFR/IFR developing after 06Z and after
00Z for ACK. Higher risk is south of the Mass Pike, but there is
potential for it to nudge as north as BOS. Afternoon SHRA/TSRA 
chances return Friday, but uncertain how far east impacts could 
reach at this time.

KBOS Terminal...Moderate confidence.

Should more likely stay MVFR this AM with low chance for brief
IFR cigs. Improving to VFR 14-16Z. Winds SSW at 8-10 kts. Low 
probability for a sea breeze trying to push in by 17Z if winds 
are light enough. 

Potential for IFR ceilings to nudge in after 06Z Fri. 

KBDL Terminal...High confidence.

Low chance remains for an isolated afternoon SHRA or TSRA 
across western areas of southern New England, with PROB30 for 
TSRA after 20z today.

Outlook /Friday Night through Monday/...

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

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

Saturday Night: VFR. Breezy. Slight chance SHRA.

Sunday: VFR. Breezy. 

Sunday Night: VFR. 

Monday: VFR. Breezy. Slight chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Friday... High Confidence.

A few periods of gusty SW winds near 20 kts are possible today 
across the southern waters. Winds calm Friday as high pressure 
builds over the region. Waters and winds will be below SCA for 
the foreseeable future.

Outlook /Friday Night through Monday/...

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

Saturday: Winds less than 25 kt. Areas of seas approaching
5 ft. 

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

Sunday through Sunday Night: Winds less than 25 kt. Areas of
seas approaching 5 ft. 

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory from 11 AM this morning to 8 PM EDT Friday for 
     CTZ002>004.
MA...Heat Advisory from 11 AM this morning to 8 PM EDT Friday for 
     MAZ003>007-010>021-026.
RI...Heat Advisory from 11 AM this morning to 8 PM EDT Friday for 
     RIZ001>007.
MARINE...None.

&&

$$

DISCUSSION...McMinn
AVIATION...McMinn/Mensch
MARINE...McMinn