Old Res Weather

Lexington, Massachusetts, USA

35°F

2/16/2025 7:17pm

Lexington Conditions: Partly cloudy
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 040530
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
130 AM EDT Fri Sep 4 2026

.WHAT HAS CHANGED...
No significant changes to the forecast.

&&

.KEY MESSAGES...

- A few rounds of scattered showers and t-storms possible each 
afternoon. Best chance is Thursday evening, then Saturday. 

- Fall-like feel for Sunday, then more seasonable for Labor Day. A 
gradual warm-up throughout the week with continued dry weather 
through at least Wednesday or Thursday.

- Elevated risk for dangerous rip currents through the Holiday 
 Weekend, especially Sunday into Labor Day.

&&

.DISCUSSION...
KEY MESSAGE 1...A few rounds of scattered showers and t-storms 
possible each afternoon. Best chance is Thursday evening, then 
Saturday. 

The frontal wave has brought a good amount of dry mid-level air in 
its wake allowing for plenty of breaks of sun, especially for 
western SNE. Mesoanalysis indicates about 1500 J/kg of surface based 
CAPE. High-resolution guidance has backed off on the coverage of 
convection with this second wave of precip chances for the afternoon 
and evening likely owing to the lingering cloudy skies/morning rain 
showers resulting in a less favorable environment. Even the latest 
HRRR is not initializing well, showing widespread convection at 19z 
while the radar remains nearly bare. Even so, as the front drops 
south it may kick off some isolated convection, expected to be sub 
severe with frequent lightning the main threat. The greatest threat 
will be along and south of the frontal boundary, mainly south of the 
MA pike. 

Looking toward the Friday-Saturday period, drier NW flow kicks in 
with PWATs dropping down to around an inch or less. Expecting this 
to result in a mostly dry stretch with a mix of clouds and sun. Even 
so, with a mid level trough and low pressure just offshore we'll 
still see periodic diurnal shower chances. Certainly not a washout, 
but keeping low probability rain chances in the forecast, mainly for 
Saturday afternoon. 

Friday will be the warmest day of the whole forecast as a slightly 
warmer airmass pushes in; 850 mb temps briefly reach ~15C Friday 
before dropping to ~8C Saturday resulting in high temperatures in 
the low to mid 80s and low to mid 70s respectively. 

KEY MESSAGE 2...Fall-like feel for Sunday, then more seasonable for 
Labor Day. A gradual warm-up throughout the week with continued dry 
weather through at least Wednesday or Thursday.

Saturday night through the middle of the upcoming week features 
fairly benign conditions, with little in the way of rainfall 
chances. The 500mb forecast map shows somewhat of an omega ridge 
centered across the middle of the country, with a closed mid-level 
low centered over Nova Scotia Sunday afternoon. The omega ridge 
flattens out, with semi-zonal flow developing across the coast by 
Tuesday and then shortwave troughing for late week across the 
northeastern states, likely leading to the next chance for active 
weather for southern New England. At the surface, high pressure 
builds in from the northwest Sunday, with its origins in northern 
Canada. Surface high pressure remains the dominant weather feature 
throughout the majority of the forecast period, leading to a stretch 
of dry weather.

Temperatures aloft are cooler Sunday, associated with that mid-level 
low east of New England. 925mb temperatures are only around +8C to 
+10C, which with boundary layer mixing supports highs in the upper 
60s to low 70s. Thus, Sunday will feel very much like autumn, with a 
blend of sun and clouds, northerly winds and dew points in the low 
50s. While winds won't be overly strong, the combination of cooler 
temperatures and lower dew points will make for a rather crisp day. 
Sunday night could feature some decent radiational cooling as high 
pressure settles across the region, though this will depend on how 
quickly winds diminish. If winds become light enough, NBM guidance 
may be too warm across the typically cooler, effective radiators. 
For example, the NBM has KOWD around 54F, while the cooler CONSMOS 
guidance suggests temperatures could fall as low as the mid to upper 
40s. Otherwise, lows are generally expected in the 50s.

Good news if you aren't ready for pumpkin spice weather, as 
temperatures will trend warmer throughout the week from WAA aloft. 
925mb temperatures climb +14C to +18C, supporting near-seasonable 
highs in the upper 70s for Labor Day, then upper 70s to lower 80s 
Tuesday into the middle part of next week. Humidity remains 
tolerable as well, with dew points generally in the upper 50s to 
around 60F. Labor Day itself looks quiet and dry, though there will 
be a high risk for rip currents along the ocean beaches.

KEY MESSAGE 3...Elevated risk for dangerous rip currents through the 
Holiday Weekend, especially Sunday into Labor Day.

Persistent northeast flow, long-period swell, and offshore seas of 4-
7 feet will continue to support an elevated risk for dangerous rip 
currents through the Holiday Weekend, especially Sunday into Labor 
Day for east-facing ocean beaches. With otherwise quiet weather 
expected, those heading to the beach should be mindful that ocean 
conditions may still be hazardous. Be sure to check with local beach 
staff or lifeguards regarding ocean conditions before entering the 
water.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels...

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

Update: 06z TAF

Through 12z Friday...Moderate confidence in timing.


Confidence has marginally increased with this update as the
well-advertised areas of marine stratus has pushed over eastern
Massachusetts. An area of marine stratus off the coast of Maine
will advect southwest into eastern Massachusetts overnight, 
including KBOS. Expecting this feature to quickly dissipate
around or shortly after 12z as the winds shift more to the W.
Until then wind direction is light and variable at terminals
across southern New England. The light winds, in combination
with wet ground and periods of mostly clear skies, is allowing
for areas of radiation fog and locally lower VISBYs across the
CT River Valley. 

Today...Moderate confidence in trends, lower confidence in 
timing.

Between 12-15z, conditions improve to VFR for most, with the 
exception of the outer Cape and KACK. There, it may take well into 
the early afternoon for conditions to improve to VFR. Light north-
northwest winds for most, though a sea breeze develops across 
eastern coastal Massachusetts, including KBOS.

Friday Night...High confidence.

VFR. Light northwest winds.

KBOS Terminal...Low confidence.

Areas of stratus and fog continue IFR with MVFR visibilities 
roughly through 12z. Some improvement to MVFR is possible 
during the morning push, otherwise trending to VFR after 14/15z. 
An onshore wind is also anticipated for much of the day today.

KBDL Terminal...Moderate confidence.

Areas of MVFR/IFR conditions contingent upon the development of
low stratus/fog. Any reduced flight categories resolve shortly
after 12z. 

Outlook /Saturday through Tuesday/...

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

Saturday Night: Mainly VFR, with local MVFR possible. Breezy.
Slight chance SHRA.

Sunday: VFR. Breezy. 

Sunday Night through Tuesday: VFR.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today through Friday Night...

Winds shift to the west/northwest through Thursday night into
Friday morning before shifting to the S/SW late Friday. A few
showers and t-storms may move over the southern waters this
evening then tranquil weather persists. Seas 2-3 ft.

Outlook /Saturday through Tuesday/...

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

Saturday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. 

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

Sunday Night through Labor Day: Winds less than 25 kt. Local
rough seas. 

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

DISCUSSION...BW/Dooley
AVIATION...Dooley/FT
MARINE...BW/Dooley