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 180513
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
113 AM EDT Sun Oct 18 2026

.WHAT HAS CHANGED...
Gale Watches issued for our southern waters early next week.

&&

.KEY MESSAGES...

- Diminishing winds and clearing tonight with cold low temps in the 
  20s and 30s with widespread frost/freeze conditions. Sunshine 
  returns on Sunday with highs in the 50s with light winds.

- Mainly dry for the upcoming workweek except near coastal 
  areas. Otherwise, the other big story is a modest warming 
  trend with high pressure building in across the Northeastern 
  United States.

&&

.DISCUSSION...
KEY MESSAGE 1...Diminishing winds and clearing tonight with cold 
low temps in the 20s and 30s with widespread frost/freeze conditions. 
Sunshine returns on Sunday with highs in the 50s with light winds.

Model cross sections indicate that lingering mid level cloudiness 
pushes south of the region tonight. This combined with high pressure 
building in from the west coupled with diminishing winds and a dry 
airmass in place will set the stage for a cold night. Low temps 
should bottom out in the middle to upper 20s in many locations with 
lower to middle 30s common in the urban heat islands as well as the 
Cape/Nantucket where winds will not decouple. Widespread 
frost/freeze conditions expected...But our Frost/Freeze program has 
ended already so no headlines needed.

High pressure will result in sunny skies for Sunday. High temps will 
be in the 50s...which is a bit below normal for this time of year. 
However...with very little wind outside the Cape/Islands it will 
feel significantly milder by afternoon than today. 

High pressure remains in control of our weather Sunday night with 
mainly clear skies. This will result in another good night of 
radiational cooling with lows in the 20s and 30s.

KEY MESSAGE 2...Mainly dry for the upcoming workweek except near 
coastal areas. Otherwise, the other big story is a modest warming 
trend with high pressure building in across the Northeastern United 
States. 

General theme for the long term forecast is the return of drier and 
somewhat warmer conditions going into the workweek as a broad ridge 
of high pressure develops over the CONUS. Outside of this, guidance 
continues to indicate the development of low pressure towards the 
mid-Atlantic/Carolina coastal waters later Sunday into the day on 
Monday. Ironically, this feature stems from last night's cold front 
as it continues to move offshore and stall into a stationary 
boundary. At the same time, lingering upper level energy cuts off 
and induces the development of a frontal wave off the coast of the 
Carolinas later Saturday night into Sunday morning. Still see a 
signal for enough of a weakness in the ridge for low pressure to 
move N and affect coastal areas Monday and Tuesday. Have continued 
to see drier solutions with this storm as a dry airmass precedes the 
northward precip shield. 12z global guidance QPF looks quite 
limited, with ensemble probabilities for any measurable rainfall 
mostly between 10-50%, with the GEFS and Canadian ENS skewing 
slightly higher over the Cape and Islands at 50-60%. The ECMWF 
ensemble is the lowest of the three, with the highest probabilities 
over land being 10-30%. However, marine impacts with this 
disturbance are looking a bit more impactful as it stays relatively 
stationary and churns over the same waters for an extended period of 
time, which will help build seas up to 15 ft offshore of Nantucket.
 
The gradient between this area of low pressure and the preexisting 
high pressure over southern New England will tighten greatly, 
increasing ENE winds over the waters and towards the Cape and 
Islands, RI, and the coastal plain in SE MA. Ensembles have 
continued to indicate decent probabilities of sustained winds 
reaching gale-force over the southern waters, with the GEFS and 
Canadian ensemble up to 30-40% (and even up to 60% in the Canadian 
guidance) just south of the Islands. In terms of gale- force gusts, 
probabilities have increased further from the last update, reaching 
the high (80-100%) range in the ECMWF ensemble and up to 80% in the 
GEFS. Persistent easterly fetch associated with these winds, along 
with building rough seas, will need to be monitored as well, as 
beach erosion for east- and northeast- facing beaches may become an 
issue.

&&

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...

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

06z Update...

Today...High confidence.

VFR. Calm/light winds continuing through the day today, with the
exception of N to NE winds between 5-15 kt across the Cape and 
Islands. Gusts over ACK early this morning die off around 14z.
VRBL conditions a possibility across interior terminals during
the day as high pressure continues aloft.

Tonight...High confidence.

VFR. Light SE to S winds that may also go calm, then become more
N-ly towards daybreak Monday. Gusts to around 20 kt possible
towards the Islands closer to daybreak Monday as well.

Monday...Moderate confidence.

Mostly VFR with the exception of the Cape and Islands towards
the late afternoon and evening hours where MVFR ceilings may
develop. Chances for -SHRA increase there as well and should
remain generally over the Cape and Islands, along with an
increased chance for gusts to 25 kt. Winds from the NE and light
to calm further inland, 5-10 kt sustained closer to the coasts.

KBOS Terminal...High confidence in TAF. 

KBDL Terminal...High confidence in TAF.

Outlook /Monday through Thursday/...

Monday: VFR. Breezy. 

Monday Night: VFR. Windy with local gusts up to 30 kt. 

Tuesday: VFR. Windy with gusts up to 30 kt. 

Tuesday Night: VFR. Windy with gusts up to 35 kt. 

Wednesday: Mainly VFR, with local MVFR possible. Windy with
gusts up to 35 kt. 

Wednesday Night: Mainly VFR, with local MVFR possible. Windy
with areas of gusts up to 35 kt. Slight chance SHRA.

Thursday: Mainly VFR, with local MVFR possible. Windy with
gusts up to 30 kt. Slight chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Tonight through Sunday night...High confidence.

N wind gusts of 20 to 30 knots persist tonight...strongest of which 
will be across our southern waters. Small craft headlines continue 
for most of our waters. Some marginal lingering small craft advisory 
conditions may persist across the southern waters Sun morning. 
Otherwise...high pressure building in from the west will result in 
winds/seas below small craft much of Sun into Sun evening. 
However...distant ocean storm off the mid-Atlantic coast should 
result in small craft advisory seas/wind gusts returning for our 
southern waters toward daybreak Mon. Additional marine headlines 
will be needed for much of the upcoming work week because of this 
ocean storm. 

Outlook /Monday through Thursday/...

Monday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Rough seas up to 14 ft. Chance of rain showers. 

Monday Night: Low risk for gale force winds with gusts up to
35 kt. Rough seas up to 14 ft. Chance of rain showers. 

Tuesday: Strong winds with gusts up to 40 kt. Rough seas up to
14 ft. Chance of rain showers. 

Tuesday Night: Moderate risk for gale force winds with gusts up
to 45 kt. Rough seas up to 14 ft. Chance of rain showers. 

Wednesday through Wednesday Night: Moderate risk for gale force
winds with local gusts up to 45 kt. Rough seas up to 15 ft.
Chance of rain showers. 

Thursday: Strong winds with gusts up to 40 kt. Rough seas up to
14 ft. Chance of rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 AM EDT early this morning for 
     ANZ231-251.
     Small Craft Advisory until 8 AM EDT this morning for 
     ANZ232>235-237-250.
     Small Craft Advisory until 11 AM EDT this morning for 
     ANZ254>256.
     Gale Watch from Monday evening through Wednesday morning for 
     ANZ254>256-281>283.

&&

$$

DISCUSSION...Frank/FT
AVIATION...Frank/Hrencecin/FT
MARINE...Frank/FT