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 031916
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
316 PM EDT Mon Aug 3 2026

.WHAT HAS CHANGED...
No significant changes.

&&

.KEY MESSAGES...

- Last round of showers and thunderstorms pushes through this
  afternoon and evening with the arrival of a cold front. Dry 
  and seasonable day expected Tuesday. 

- Summer heat and humidity slowly returns later Wed, then peaks
  Thu/Fri and likely lingers into the weekend. Diurnal 
  scattered thunderstorms each day, but many hours of dry 
  weather too, hence, not a washout. 

&&

.DISCUSSION...
KEY MESSAGE 1...Last round of showers and thunderstorms pushes
through this afternoon and evening with the arrival of a cold 
front. Dry and seasonable day expected Tuesday.

Expect widespread showers with pockets of moderate to heavy rain 
possible through the late afternoon. A cold front approaches 
from the west with a leading line of scattered showers and 
thunderstorms. Originally this posed a threat for some strong to
severe thunderstorms. We are still in a marginally unstable 
airmass with SPC mesoanalysis SBCAPE values around 500-1,000 
J/kg accompanied by rich moisture. Enough to support 
thunderstorms in the mix of that line. The risk for severe will 
be on the lower side as we didn't have enough clearing to allow 
the  to re- bound/destabilize enough. Given the deep moisture, 
brief downpours are also possible within these cells. This line 
will push through western MA this afternoon then clearing the 
east coast by 8 PM. Winds decrease and shift to the west with 
the cold front accompanied by scattering and clearing clouds. 
Dry conditions expected tonight. Can't rule out some patchy fog 
in the valleys and the Cape/Islands once they areas clear if 
there is any residual moisture. 

Quiet day for Tuesday with a weak mid-level ridge building over the 
region. This will support dry conditions and seasonable temperatures 
in the low to mid 80s. 

KEY MESSAGE 2...Summer heat and humidity slowly returns late Wed, 
then peaks Thu/Fri and likely lingers into the weekend. Diurnal 
scattered thunderstorms each day, but many hours of dry weather too, 
hence, not a washout. 

Summer heat and humidity slowly returns later Wed and then peaks 
Thu/Fri and likely continuing into the weekend, as ensembles are in 
good agreement on 597+ dam 500 mb subtropical ridge/Bermuda high 
building across the Western Atlantic. This will circulate a very 
warm and humid airmass into SNE, with dew pts 70-75 Thu/Fri and 
possibly lingering into the weekend. With 925 mb temps 22C+ each 
afternoon, highs 85-90 are likely and combined with dew pts of 70-
75, heat headlines are possible late this week and possibly into the 
weekend. 

Synoptic scale forcing is very weak Thu and Fri,thus, many hours of 
dry weather. However, short wave energy will eject northeast from 
remnant closed low currently over the southeast states into SNE. 
Then over the weekend, mean trough axis sets up from central Canada 
into the Western Great Lakes, with broad cyclonic flow into New 
England. This combined with heat/humidity/instability will be 
sufficient for typical summer, scattered diurnal convection Thu/Fri 
and into the weekend. With PWATs +1.5 to +2.0 sigma, any storm will 
have the potential for tropical/torrential downpours. Again, many 
hours of dry weather too during this time period. Thus, not a 
washout. 

&&

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

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

18Z TAF Update: 

Today: Moderate confidence. 

Periods of RA this afternoon decrease front west to east 
21-02Z. Pockets of moderate to heavy rates possible. IFR/LIFR in
RA/+RA. A last round scattered showers and thunderstorms likely
pushes through from west to east 18Z-00Z ahead of the 
approaching cold front. SW winds 10-20 kts with gusts 20-30 kts,
highest gusts for the Cape & Islands. 

Tonight: High confidence. 

Last of the scattered showers and storms push off the east MA
and the Cape 23-02Z. Otherwise expect a trend of improving
conditions with ceilings improving to VFR between 22Z(west) and
02Z (Cape/Islands). Patchy fog possible in valleys and for Cape
and Islands once they clear. Winds shift to the W/WNW behind the
front (22-02Z) at 5-10 kts. 

Tuesday: High confidence. 

VFR. Winds 5-10 kts, first W then becoming SW after 18Z.
Potential for a late-day sea breeze for BOS.

KBOS Terminal...Moderate confidence in TAF. 

-SHRA/SHRA this afternoon. A trailing line of scattered showers
 and thunderstorms is possible 21-00Z. Lower confidence on the 
 potential for TSRA, but enough to include as a PROB30 given the
 unstable environment today. Conditions improve to VFR 23-01Z 
 with the front as winds shift toward the W by 03Z. Winds become
 more SW tomorrow morning with potential for a late-day sea 
 breeze. 

KBDL Terminal...Moderate confidence in TAF.

Outlook /Tuesday through Saturday/...

Tuesday through Wednesday Night: VFR. 

Thursday: VFR. Breezy. Slight chance SHRA, isolated TSRA.

Thursday Night: Mainly VFR, with local IFR possible. Chance
SHRA.

Friday: Breezy. Chance SHRA.

Friday Night: Breezy. Slight chance SHRA.

Saturday: Breezy. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Seas and winds slowly decrease tonight into Tuesday. Seas will
be slowest to fall across the southern waters with seas 5-9 ft
gradually falling to 5-6 ft toward sunrise. SW winds 15-20 kts 
with gusts around 30 kts. Can't rule out a few isolated gusts 
near gale force for the remainder of the afternoon. Winds
decrease after 00Z and below 25 kts by 06Z. Seas remain elevated
Tuesday keeping up SCAs for the southern and eastern outer
coastal waters. 

A high surf advisory is in effect for the south coast and 
islands through tonight with seas 5-9 ft across the waters of 
RI and south of MVY-ACK. Rough surf and strong rips are likely to
linger into Tuesday from the prolonged strong SW flow/swell.
With Tuesday being a nice beach day, issued a Rip Statement for
the south coast and Islands for Tuesday with the high risk for
rip currents. There is a moderate risk for rip currents for the
east-facing beaches along the outer Cape. 

Outlook /Tuesday through Saturday/...

Tuesday: Winds less than 25 kt. Seas up to 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. Slight chance of rain showers. 

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

Friday through Friday Night: Winds less than 25 kt. Seas up to
5 ft. 

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Risk for Rip Currents from late tonight through Tuesday 
     evening for MAZ020-023-024.
     High Surf Advisory until 9 PM EDT this evening for MAZ023-024.
RI...High Risk for Rip Currents from late tonight through Tuesday 
     evening for RIZ006>008.
     High Surf Advisory until 9 PM EDT this evening for RIZ006>008.
MARINE...Small Craft Advisory until 5 PM EDT this afternoon for ANZ230-
     236.
     Small Craft Advisory until 8 PM EDT this evening for ANZ231-
     251.
     Small Craft Advisory until 2 AM EDT Tuesday for ANZ232>234.
     Small Craft Advisory until 2 PM EDT Tuesday for ANZ235-237-250-
     254.
     Small Craft Advisory until 8 PM EDT Tuesday for ANZ255-256.

&&

$$

DISCUSSION...Mensch/Nocera
AVIATION...Mensch
MARINE...Mensch/Nocera