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

Southeast Middlesex County, MA - Heat Advisory
- SEE ALL NEARBY ALERTS -

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 101736
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
136 PM EDT Wed Jun 10 2026

.WHAT HAS CHANGED...
Heat Advisories have been issued for interior MA and northern 
CT from noon Thursday until 8PM Friday. Increasing confidence in
a few storms possibly becoming severe in nature Thursday 
evening.

&&

.KEY MESSAGES...

- Chances for showers and thunderstorms return this afternoon
  into tonight.

- Heat Advisories have been issued across interior MA and
  CT Thursday into Friday. Diurnal thunderstorms remain a
  possibility during the afternoon and evening hours Thursday
  and Friday.

- Temperatures remain warm with decreasing humidity throughout 
  the weekend, while uncertainty remains high regarding 
  potential for rain showers.

&&

.DISCUSSION...
KEY MESSAGE 1...Chances for showers and thunderstorms return 
this afternoon into tonight.

A warm front associated with low pressure system tracking 
through the Great Lakes and southern Ontario will sweep through 
southern New England will bring some showers and possibly 
thunderstorms to the region later this afternoon and into the 
overnight period. Potential for severe still seems low, with the
CSU ML probabilities remaining at a 5-15 percent chance for 
severe wind across western MA and CT. Similar trends are being 
seen in the latest run of the HRRR Neural Network, with highest 
potential for severe winds across interior MA and CT tonight. 
Given winds turning southwesterly today, expecting to see 
dewpoints and PWATs surge... the latest model guidance is 
indicating PWATs 1.9"-2.0" across most of southern New England, 
with pockets of up to 2.2" possible across central and southern 
CT heading into the early Thursday morning hours. Unfortunately,
confidence in where exactly storms could initiate remains on 
the lower side. Latest guidance continues to keep the heaviest 
rainfall in northern New England and offshore to the south... 
regardless, any rainfall that does form is likely to be heavy in
nature.

KEY MESSAGE 2...Heat Advisories have been issued across 
interior MA and CT Thursday into Friday. Diurnal thunderstorms 
remain a possibility during the afternoon and evening hours 
Thursday and Friday.

Confidence continues to increase that heat and humidity will 
pose a risk Thursday and Friday. As the warm front from 
Wednesday lifts further north, prolonged southwesterly flow will
bring a surge of very hot and humid air, especially as 925mb 
temperatures increase to +27C Thursday and up to +30C Friday. 
Surface dewpoints are likely to top out in the upper 60s to low 
70s, especially across interior MA and northern CT. These high 
dewpoints combined with temperatures climbing into the low to 
mid 90s will lead to heat index values approaching 100F Thursday
and likely above 100F Friday across the CT River Valley, 
prompting Heat Advisories to be issued for northern CT and 
western MA from noon Thursday until 8PM Friday.

Temperatures across RI and eastern MA likely remain in the mid 
80s to low 90s across both days. Dewpoints surging to near 70 
will lead to heat indicies in the low 90s, especially away from 
the coastal plain. Heat Advisories may be expanded further east;
however, a backdoor cold front is expected to drop into eastern
MA sometime on Friday. Onshore flow will provide some relief 
from the heat Friday, but the question remains how far inland 
the front will drop. Regardless, widespread moderate heat 
impacts across the region, with major impacts expected in the CT
River Valley, both Thursday and Friday, leading to an increased
risk of heat-related illness for anyone spending extended time 
outdoors without adequate hydration or access to cooling.

The increased heat and humidity combined with a series of weak 
upper- level disturbances will also set the stage for higher 
chances of showers and thunderstorms Thursday and Friday, with 
increasing potential that some storms Thursday may be severe in 
nature. CSU ML probabilities have increased to 15-30 percent for
severe wind potential and 5-15 percent chance to see small hail
across the interior. Latest guidance is showing CAPE values of 
1300+ J/kg Thursday evening, with pockets of up to 2000 J/kg 
possible across far western CT... however, those higher values 
are likely to rapidly decay as they push east, which would lead 
to short-level cells. Regardless, confidence has increased 
enough to upgrade the western portion of southern New England 
from General Thunderstorms to a Slight Risk for severe weather 
Thursday.

KEY MESSAGE 3...Temperatures remain warm with decreasing 
humidity throughout the weekend, while uncertainty remains high 
regarding potential for rain showers.

Anticipating the passage of a couple fronts Saturday and 
Sunday. The main impact will be lower humidity, with Sunday 
anticipated the drier of the two. Lingering showers possible 
Saturday, but plenty of dry hours too. Some guidance members 
indicated a weak low pressure passing by towards the south coast
of New England sometime Monday into Tuesday. Kept a mention of 
showers in the forecast, but confidence in these details is low.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Forecaster Confidence Levels...

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

Through Tonight...High confidence to start, moderate confidence
towards the nighttime hours.

VFR conditions continue for the rest of the afternoon. Some 
MVFR to localized IFR conditions may overspread parts of the 
region from southwest to northeast by early this evening along 
with a few showers. Showers become more likely tonight and
coverage looks limited as the activity makes its way from west
to east. Greater chance for -TSRA/-SHRA across western
terminals.

Gusts to around 20 kt continue thru the early evening SW winds 
will shift more S in the wake of a passing warm front later 
today into tonight. Winds become light as an inversion moves
overhead.

Thursday...Moderate confidence.

Generally MVFR/IFR conditions. Improvement from showers and fog
overnight will likely be slow (not until 12z or later). Some 
areas could be on the cusp of LIFR conditions as any lingering 
showers push offshore. SW winds continue through the morning 
hours, generally around 10 kts once showers move out.

KBOS Terminal...High confidence in trends. Moderate confidence 
in timing. TEMPO for -SHRA continues from 01-05z.

KBDL Terminal...High confidence in trends. Moderate confidence 
in timing. Timing for SHRA and later TSRA still a bit uncertain.
Included as TEMPOs for now.

Outlook /Thursday Night through Monday/...

Thursday Night: VFR. Slight chance SHRA.

Friday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.

Friday Night: Mainly VFR, with local IFR possible. Chance SHRA,
slight chance TSRA.

Saturday through Saturday Night: VFR. 

Sunday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Thursday Morning...High confidence.

Winds shift more SW then SSW Wednesday afternoon, sustained at 
around 15-20 kt with gusts remaining just below Small Craft 
criteria. Seas generally 2-4 ft through Wednesday night, though 
the southern outer waters may start to creep to 5 ft heading 
into Thursday morning.

Outlook /Thursday Night through Monday/...

Thursday Night: Winds less than 25 kt. Seas up to 5 ft. Chance
of rain showers, slight chance of thunderstorms. 

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

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

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

Sunday: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory from noon Thursday to 8 PM EDT Friday for 
     CTZ002>004.
MA...Heat Advisory from noon Thursday to 8 PM EDT Friday for MAZ002-
     003-008>011.
RI...None.
MARINE...None.

&&

$$

DISCUSSION...McMinn
AVIATION...Hrencecin/FT
MARINE...McMinn