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 161702
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
102 PM EDT Fri Oct 16 2026

.WHAT HAS CHANGED...

No significant changes.

&&

.KEY MESSAGES...

* Showers this morning followed by a lull in activity for much of 
  the afternoon aside from a few spot showers. Another round of 
  showers with some embedded thunderstorms possible move through 
  between 5-11 pm. Windier and colder Saturday following a strong 
  cold front.

* Chilly night Saturday night with below-freezing low temperatures 
  away from the coasts.

* Dry with more seasonable through early next week, though
  monitoring coastal storminess near or south of the mid-
  Atlantic waters towards the midweek period.

&&

.DISCUSSION...
KEY MESSAGE 1...Showers this morning followed by a lull in activity 
for much of the afternoon aside from a few spot showers. Another 
round of showers with some embedded thunderstorms possible move 
through between 5-11 pm. Windier and colder Saturday following a 
strong cold front.

High pressure continues to drift off to the east early this morning 
and showers have starting to make their way into parts of western MA 
and CT. These will continue to track through the region this 
morning, spreading from west to east. This is associated with a 1004 
mb low pressure system currently over the Great Lakes region that 
will track along the southern Ontario/Quebec and northeast US border 
as the day goes on. As it does, the low is expected to continue 
deepening as its associated upper level shortwave trough also 
deepens, cutting well into the Midwest by this evening. Showers this 
morning will likely last a few hours at any given location. Winds 
have already shifted more southerly this morning, which will help 
kick off the advection of an anomalous moisture plume and warmer 
air. PWATs up to 1.75" and even approaching 2.0" will creep into 
southern New England as the low's warm front moves through by the 
early afternoon. Once this warm front tracks through, the system's 
warm sector will settle overhead for the afternoon. This will 
provide a bit of a respite from steady showers ahead of the next 
expected round of rain, though a few spot showers cannot be 
completely ruled out. 925 mb temperatures while under this warm 
sector will increase to the 16-18C range with 850 mb temperatures 
around 15C as warm air advection moves in full force. Highs will 
likely reach the upper 60s and low 70s as a result. A southerly LLJ 
also sets up, with the core of it at 925 mb ranging between 45-50 
kt. Amidst some of the model discrepancies, the general agreement is 
the core of this will be just over the eastern waters in the 
afternoon, reaching up to 60 kt (though the NAM goes even higher at 
65 kt). This same signature is also noted at 850 mb. Model soundings 
do, however, indicate an inversion at the low to mid levels which 
would inhibit this jet from fully mixing down. Gusty winds to 30 mph 
are not out of the question, and some could see 35 mph gusts closer 
to the eastern coastlines. Cloudy conditions persist through the day 
as well, given the abundant moisture aloft.

Our concern then turns to the next round of rain towards the evening 
hours, which could include some embedded thunderstorms. Not much has 
changed in the CAMs for the 5-11 pm timeframe today, as they've 
continued to show the development of a "fine line" tracking from 
west to east across the region. High-res guidance still indicates a 
few hundred J/kg this afternoon and evening ahead of the low's 
strong cold front, though 0-6 km effective bulk shear is in the 50-
60 kt range with strong jet dynamics. Given this environment, some 
embedded thunderstorms could develop as this line of showers moves 
through southern New England. Even with the forcing from the 
approaching cold front, the limited instability should keep the 
severe potential for any embedded thunderstorms that may develop 
quite low. This high shear/low CAPE environment may still produce 
some instances of sub-severe gusts to 50 mph though, and much of 
southern New England is under a Marginal (1/5) risk for severe 
weather today. Western portions of central CT are in a Slight (2/5) 
risk for severe weather today, though also for the risk of severe 
and damaging winds. Latest CSU ML guidance has much of the northeast 
under a 5-15% chance for severe winds today as well, so it cannot be 
entirely ruled out. This will continue to be monitored ahead of and 
during the event.

Some of the high-res guidance also showed a signal for a some post-
frontal rain across southeastern New England, though by the time 
this arrives, the threat for any embedded thunderstorms will have 
dropped considerably. Event rainfall totals are expected to 
generally range between 0.3-0.7" across southern New England. 
Depending on where some embedded thunderstorms/more convective 
showers set up, some spots could see locally higher totals, 
especially given the high PWAT environment.

KEY MESSAGE 2...Chilly night Saturday night with below-freezing low 
temperatures away from the coasts.

As the cold front crosses southern New England through Saturday 
morning, strong cold air advection is left in its wake. 925 mb 
temperatures fall below 0C by Saturday evening, and PWATs fall below 
0.25" once more as colder, drier air sets in. Lows Friday night fall 
into the 40s and upper 30s (towards the high elevations). Highs 
Saturday may struggle to reach the low 50s across the interior and 
lows Saturday night will likely dip below freezing across the 
region, with the exceptions being areas closest to the coasts and 
urban areas. Once the gusty NW winds drop off earlier in the 
overnight period Saturday, we could see some radiational cooling 
develop as high pressure builds in post-FROPA, enhancing an already 
relatively cold night for some locations.

KEY MESSAGE 3...Dry with more seasonable through early next week, 
though monitoring coastal storminess near or south of the mid-
Atlantic waters towards the midweek period.

High pressure continues to build in Sunday and a more seasonably 
cool airmass moves into the region, and the tighter gradient between 
the strong exiting low and approaching high pressure slackens. This 
will allow winds to let up as well, diminishing slightly heading 
into the second half of the weekend and the start of next week. As 
high pressure settles overhead as well, temperatures will moderate 
back to more typical levels for this time of year as highs return to 
the 50s and 60s into early next week. One thing we will be keeping 
an eye on, though, is the development of a cutoff low towards the 
mid-Atlantic/Carolina coastal waters. This feature appears to have 
detached from the broader upper level trough that was associated 
with the strong low pressure that is impacting us today. There is 
some uncertainty with regards to our region seeing any impacts from 
this cutoff low, especially given the strength of the ridge overhead 
during this point in the forecast. Even then, at most, it would lead 
to some scattered showers towards the Cape and Islands at closest 
and more NE breezes. Much can change between now and this timeframe, 
but as of now, impacts look minimal to zero.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...

Forecaster Confidence Levels...

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

18z TAF Update...

This afternoon into this evening...Moderate confidence.

IFR to localized LIFR conditions dominated the region at mid
afternoon. There were still a few showers across RI/southeast
MA...but otherwise most of the region was in a lull with just
areas of drizzle and fog. Main concern is between 22z and 02z 
as a cluster showers and potentially embedded t-storms sweeps 
across the region. Greatest risk for thunder will be across 
CT/RI/SE MA...but that is possible across the rest of the region
as well. Brief localized strong wind gusts/heavy rainfall may 
accompany this cluster of showers even if there is not any 
lightning. 

Otherwise...LLWS will continue to be an issue at times into this
evening. 

Overnight into Saturday...High confidence. 

Conditions should improve to VFR across most areas northwest of
I-95 later this evening. Scattered showers will linger well 
into the overnight hours and even into part of Sat across 
parts of RI/SE MA...especially across the Cape/Islands allowing 
lower ceilings lingering a bit in this region. Meanwhile...the 
rest of the region will see VFR conditions as drier air works 
into the region. NW winds gusts will increase to between 20 and 
30 knots during the day Sat. 

KBOS Terminal...Moderate confidence in TAF. Main concern is
between 23z and 02z when a cluster of showers with perhaps
embedded thunder work across the region. Even if there is not
any thunder...brief strong wind gusts are possible with the
frontal passage. 

KBDL Terminal...Moderate confidence in TAF. Main concern is
between 22z and 01z when a cluster of showers with perhaps 
embedded thunder work across the region. Even if there is not 
any thunder...brief strong wind gusts are possible with the 
frontal passage. 

Outlook /Saturday Night through Wednesday/...

Saturday Night through Sunday: VFR. Breezy. 

Sunday Night: VFR. 

Monday: VFR. Breezy. 

Monday Night: VFR. Breezy. Slight chance SHRA.

Tuesday: VFR. Breezy.

&&

.MARINE...

Forecaster Confidence Levels...

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

Through Saturday...High confidence.

Intensifying low pressure will continue to track near the northern 
New England/Quebec border today into this evening. Ahead of this 
low, strong small craft southerly wind gusts along with choppy seas 
will develop early today. 

Behind this cold front, NW wind gusts of 30-35 knots will develop 
especially late tonight into Sat morning in the CAA pattern. Latest 
guidance has still shown more marginal Gale conditions, so a Gale 
Watch remains over these areas. Despite marginal conditions, cold 
air advection patterns can often overperform this time of year given 
relatively warm SST which can enhance mixing. Either way, strong SCA 
to gale force wind gusts are expected with choppy seas.

Outlook /Saturday Night through Wednesday/...

Saturday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Rough seas up to 8 ft. 

Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of seas approaching 5 ft. 

Sunday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. 

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

Monday Night: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Chance of rain showers. 

Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Slight chance of rain showers.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 PM EDT Saturday for ANZ230-236.
     Small Craft Advisory until 2 AM EDT Sunday for ANZ231-251.
     Small Craft Advisory until 8 AM EDT Sunday for ANZ232>235-237-
     250.
     Small Craft Advisory until 11 AM EDT Sunday for ANZ254>256.

&&

$$

DISCUSSION...Hrencecin
AVIATION...Frank
MARINE...Hrencecin