Old Res Weather

Lexington, Massachusetts, USA

35°F

2/16/2025 7:17pm

Lexington Conditions: Mist, Overcast
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: 2 miles
Rain Today: 0.01 in
UV Index: $VPuv None

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 240538
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
138 AM EDT Mon Aug 24 2026

.WHAT HAS CHANGED...
Updated Aviation section.

&&

.KEY MESSAGES...

- Outside a few showers/isolated t-storm risk into mid evening 
  with the focus across the interior especially near and west of
  the CT River Valley. Areas of fog develop overnight which may
  become locally dense in spots. 

- Drier with a return to seasonable temperatures this week. Rain
  chances return Thursday/Friday.

&&

.DISCUSSION...
KEY MESSAGE 1...Outside a few showers/isolated t-storm risk 
into mid evening with the focus across the interior especially 
near and west of the CT River Valley. Areas of fog develop 
overnight which may become locally dense in spots. 

The main cluster of showers that resulted in brief heavy rain 
along with a rumble or two of thunder has exited the eastern Ma 
coast earlier this afternoon. Behind this activity some 
subsidence and drier mid level air was allowing the lower clouds
to begin to mix out from southwest to northeast. We will see a 
late rise in temps through early evening well into the 70s to 
perhaps near 80 in the CT River Valley as some peeks of sun try 
to develop. This will result in some modest instability 
developing with ML Capes approaching 1000 J/KG across parts of 
the interior. However...subsidence behind the earlier shortwave 
coupled with the main forcing well to our west will limit the 
additional risk. Nonetheless...a few showers and perhaps an 
isolated t-storm or two will be possible into mid- evening. The 
main focus for this activity will be across the interior and 
especially near and west of the CT River Valley closer to the 
upper level shortwave.

Otherwise...the main story later tonight will be for the 
development of fog some of which may become locally dense. Winds
become light/calm overnight coupled with partial clearing, wet 
ground and dewpoints remaining in the 60s will set the stage for
fog development. Some of the fog may become locally dense too. 
Low temperatures overnight will drop into the middle to upper 
50s in the outlying locations...to the middle 60s in the urban 
heat islands of downtown Boston/Providence. 

KEY MESSAGE 2...Drier with a return to seasonable temperatures 
this week. Rain chances return Thursday/Friday.

A post-frontal air mass ushers in drier conditions and warmer 
temperatures on westerly winds this week. As skies gradually 
clear from the dreary weekend, dewpoints will begin to drop 
slightly... into the upper 50s as opposed to the low to mid 60s 
we've been seeing. High pressure begins to slowly build Tuesday 
into Wednesday, prolonging the clear skies, drier weather, and 
warmer temperatures through the middle of the week. Expecting 
temperatures to return to seasonable, in the upper 70s to low 
80s, and feel less humid thanks to the lower dewpoints through 
the end of the week.

Chances for rain showers return Thursday and Friday as a low 
pressure system develops over the Great Lakes and meanders east 
through southern Ontario. Some uncertainty remains regarding the
onset of the showers as there's little consistency in the 
global ensembles on the actual placement of the low as it tracks
through Canada; however, confidence has ticked up slightly in a
later show of showers Thursday evening into the overnight 
period compared to yesterday's model runs.

&&

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

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

06z TAF Update...

Through 12z...Moderate confidence in trends but lower 
confidence in specific timing. 

VFR/MVFR conditions, however light winds with higher dewpoints
and remaining wet ground will remain conducive to the 
development of areas of fog. Some have already developed across
NE MA, parts of RI and SE MA, and up in the Worcester hills.
Areas all prone to fog will likely see it before daybreak if
they aren't already, and it may become locally dense.

Monday and Monday night...High confidence. 

Any leftover ground fog quickly burns off after sunrise this
morning. VFR with SW winds of 7-13 kt with a few gusts up to 20
kts possible in the afternoon/evening hours across the region, 
though ACK may remain under an inversion that prevents the 
development of gusts based on the latest forecast soundings. VFR
conditions continue tonight outside of any localized patches of
ground fog that develop in typically prone locations. Winds 
become calm/light SW overnight.

Tuesday...High confidence.

Generally VFR, though lower end VFR to higher end MVFR possible
over the interior. W winds 6-13 kt with gusts near the Cape and
Islands nearing 20 kt possible.

KBOS Terminal...Moderate confidence in TAF. Low clouds remain
possible through 12z this morning.

KBDL Terminal...Moderate confidence in trends but lower 
confidence in specific timing. Fog has not developed yet within
the valley, though could expect it to do so over the next few
hours and reach BDL before sunrise.

Outlook /Tuesday through Friday/...

Tuesday: VFR. Breezy. 

Tuesday Night through Wednesday Night: VFR. 

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

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

&&

.MARINE...
Forecaster Confidence Levels...

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

Tonight through Monday night...High confidence.

The pressure gradient will generally remain weak enough to keep
winds/seas below small craft advisory through Monday night. 
However...nearshore SW winds may gust into the lower 20 knots 
late Monday result in some decent chop for recreational boaters.

Outlook /Tuesday through Friday/...

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

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

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

Wednesday Night through Thursday: Winds less than 25 kt. 

Thursday Night through Friday: Winds less than 25 kt. Chance of
rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Risk for Rip Currents from 8 AM EDT this morning through this 
     afternoon for MAZ024.
RI...None.
MARINE...None.

&&

$$

DISCUSSION...Frank/McMinn
AVIATION...Hrencecin
MARINE...Frank/McMinn