Lexington Weather

Lexington, Massachusetts, USA

79°F

7/12/2026 2:29pm

Lexington Conditions: Mostly cloudy
Temperature: 79.3°F / 26.3°C
Dew Point: 59.0°F
Relative Humidity: 50%
Wind: Calm, 10-min avg: Calm, gust: 1 mph
Barometer: 30.11 in Steady
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 061110
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
710 AM EDT Mon Jul 6 2026

.WHAT HAS CHANGED...
The Flood Watch has been expanded across the rest of southeast 
Massachusetts into Tuesday.

&&

.KEY MESSAGES...

- Periods of heavy rain & possibly a few embedded t-storms today 
  into Tue across parts of CT/RI/SE MA. Localized flash flooding
  possible dependent on if the heaviest bands setup in our region.
  Otherwise...rain overspreads the rest of the region through tonight 
  but amounts will be lighter especially near the NH border.

- Summer warmth & humidity return for the latter half of the
  week. Mainly dry weather returns Wed into Thu...But the risk
  for a few showers & t-storms may return by Fri perhaps
  lingering into Sat.

&&

.DISCUSSION...
KEY MESSAGE 1...Periods of heavy rain & possibly a few embedded 
t-storms today into Tue across parts of CT/RI/SE MA. Localized
flash flooding possible dependent on if the heaviest bands setup 
in our region. Otherwise...rain overspreads the rest of the region 
through tonight but amounts will be lighter especially near the NH 
border.

The main forecast concern is the potential for localized flash 
flooding across parts of CT/RI/SE MA into Tue. This remains a very 
difficult forecast as the narrow bands of potentially extremely 
heavy rain are quite difficult to forecast in terms of timing and 
locations. However...the environment in place does favor the 
potential for them to form. We will discuss this in more detail 
below. 

The environment in place is favorable for the potential of localized 
flash flooding. Weak high pressure across eastern Canada was 
enforcing a shallow boundary in the vicinity of CT/NY/NJ. This 
boundary was being impinged upon by a modest southeast LLJ coupled 
with a Pwat plume of 1.5 to 2.0+ inches. The idea though is that you 
are combining winter-like synoptic features with summertime moisture 
parameters. That combination can lead to localized extreme rainfall 
events. This potential is indicated by various model suites printing 
out narrow bands of very high QPF. The issue is that these narrow 
bands of potentially extreme QPF are depicted in a lot of different 
locations depending on what model you are looking at. This is quite 
common in these cases that the models are good at indicating the 
potential for a localized torrential rain events...But struggle to 
pin the location. 

Given the above...we have expanded the Flood Watch from CT/RI across 
the rest of southeast MA. We are looking at widespread rainfall 
amounts of 1-3"...but localized 4-6" amounts would be possible 
within 6 hours if any narrow bands setup. Not all the models show 
these narrow bands developing...but many of the CAMs do and it is 
reasonable given the parameters in place. If they do develop...some 
CAMs focus it to our south while other bring it into our region. 
Regardless...the Flood Watch is certainly warranted give the 
potential if these bands are realized. 

Across the rest of the region...rain amounts will be lighter 
especially towards the NH border. In fact...it may take until later
tonight for the steady rain to finally reach northeast MA. Periods 
of rain will persist into Tuesday especially across eastern MA/RI as 
closed 850 mb low may setup a mid level deformation zone.  

KEY MESSAGE 2...Summer warmth & humidity return for the latter half 
of the week. Mainly dry weather returns Wed into Thu...But the risk 
for a few showers & t-storms may return by Fri perhaps lingering 
into Sat.

As the shortwave departs the region...a mid level ridge axis builds 
over the region with mainly dry weather returning Wed into at least 
a good part of Thu. Rising height fields should allow summer-like 
warmth and humidity to return. Highs may take a run at 90 in some 
spots by Thu. The next shortwave trough may bring the risk for a few 
showers and thunderstorms returning by Fri which may linger into 
Sat. This will depend on the timing of the shortwave/cold front.

&&

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

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

12Z TAF Update...

Today through Tuesday...Moderate confidence. 

VFR conditions early this morning will gradually deteriorate to MVFR 
levels today into tonight from southwest to northeast with brief 
bouts of IFR conditions possible too. This will be associated with 
periods of rain...which may fall heavy at times across parts of 
CT/RI/SE MA where there may even be an embedded t-storm or two. The 
process of lower cigs/vsbys and steady rain will be slowest to 
arrive across northeast MA...where it may take until this evening or 
even later for MVFR conditions to develop. Periods of rain will 
continue into Tue especially across eastern MA/RI. MVFR with 
localized IFR conditions will also continue into Tue. E winds 6-12 
knots today gradually becoming NE at 8-16 knots by Tue.

KBOS Terminal...Moderate confidence in TAF.

KBDL Terminal...Moderate confidence in TAF.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Mainly VFR, with areas IFR possible. Breezy.
Slight chance SHRA.

Wednesday: VFR. Breezy. 

Wednesday Night: VFR. 

Thursday through Thursday Night: VFR. Breezy. 

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

&&

.MARINE...
Forecaster Confidence Levels...

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

Today through Tuesday...High confidence.

Weak high pressure over eastern Canada will combined with low 
pressure tracking south of the waters. The result will be E wind 
gusts of 20 to 30 knots developing from south to north today into 
tonight and continuing into Tue shifting to more of a NE direction. 
Therefore...have small craft headlines for the open waters and seas 
building to between 3 and 5 feet. 

Outlook /Tuesday Night through Friday/...

Tuesday Night: Winds less than 25 kt. Seas up to 5 ft. Chance
of rain showers. 

Wednesday: Winds less than 25 kt. Seas up to 5 ft. 

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

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

Thursday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain
showers. 

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Flood Watch through Tuesday afternoon for CTZ002>004.
MA...Flood Watch through Tuesday afternoon for MAZ017>022.
RI...Flood Watch through Tuesday afternoon for RIZ001>008.
MARINE...Small Craft Advisory from 2 AM to 8 PM EDT Tuesday for 
     ANZ231>234-250-251-254.
     Small Craft Advisory from 11 AM this morning to 8 PM EDT 
     Tuesday for ANZ235-237-255-256.

&&

$$

DISCUSSION...Frank
AVIATION...Frank/RM
MARINE...Frank