Old Res Weather

Lexington, Massachusetts, USA

35°F

2/16/2025 7:17pm

Lexington Conditions: Partly cloudy
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 111106
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
706 AM EDT Mon May 11 2026

.WHAT HAS CHANGED...
No significant changes.

&&

.KEY MESSAGES...

- Showers mainly across far southeastern areas of southern New  
  England this morning, followed by drier conditions this 
  afternoon through Tuesday night and cooler temperatures.

- Unsettled period with increasing chances for widespread  
  soaking rain and continued cooler temperatures.

- Warmer weekend, lower confidence in sensible weather details.

&&

.DISCUSSION...
KEY MESSAGE 1...Showers mainly across far southeastern areas of 
southern New England this morning, followed by drier conditions this 
afternoon through Tuesday night and cooler temperatures.

Rain showers early this Monday morning are associated with a surface 
wave of low pressure moving along a departing cold front that 
extends from northern Maine south through the Seacoast of New 
Hampshire, then southwest toward the Jersey Shore. This cold front 
slowly moves southeast over the waters, while there remains a risk 
for light rain this morning mainly from southeast Connecticut 
through Providence to the southern Boston suburbs. The rest of the 
region should remain dry. Showers are most prevalent across coastal 
Rhode Island, the south coast of Massachusetts, Cape Cod, and the 
Islands, coming to an end by 8 AM to 10 AM, though clouds and 
showers may persist over Nantucket into the afternoon given its 
proximity to the front. Rainfall amounts are light, generally a few 
hundredths of an inch to as much as a tenth or two across Cape Cod 
and the Islands.

Behind the cold front, winds aloft shift from west to northwest, 
advecting lower humidity into the region. PWATs fall below one-third 
of an inch. Low stratus clears behind the front from northwest to 
southeast, giving way to a blend of sunshine and fair weather cu 
during the afternoon. That said, given the slow movement of the 
front, far southeast Massachusetts, Cape Cod, and the Islands may 
remain overcast into the afternoon. Associated with the drier 
airmass are cooler temperatures. 850 mb temperatures fall sharply 
from +7 to +10C Sunday afternoon to 0 to +3C Monday afternoon. 
BUFKIT soundings show deep mixing with strong cold air advection, 
supporting high temperatures in the upper 50s to mid 60s. Along with 
dew points lowering into the lower to mid 20s. Winds from the 
northwest around 10 mph with gusts up to 20 mph are expected mainly 
across central and western Massachusetts and northern
Connecticut.

Late Monday night into Tuesday morning, a fairly amplified mid-level 
trough and robust shortwave moves through southern New England. As 
mentioned, PWATs remain low, and outside of an isolated and brief 
shower, the night should be dry with intermittent low to mid-level 
cloud cover. Tuesday morning begins with low temperatures in the 
upper 30s to low 40s across most of southern New England, with the 
Cape and Islands in the mid to upper 40s. This trough shifts east 
and offshore, leading to increasing mid-level heights from the west. 
Overall, Tuesday looks pleasant albeit cool given abundant sunshine. 
With 850 mb temperatures not rebounding, expect another day of highs 
in the upper 50s to mid 60s.

KEY MESSAGE 2...Unsettled period with increasing chances for 
widespread soaking rain and continued cooler temperatures.

High pressure exits east of the region on Wednesday ahead of the 
next opportunity for active weather. Shortwave ridging provides 
drier conditions for the first half of Wednesday, but as the flow 
turns from northwest to southwest, this directional shift advects 
higher humidity and PWATs between 0.8 and 1.0 inches back into 
southern New England by late Wednesday afternoon. Exact timing 
remains uncertain, but the general idea is that morning hours are 
dry, with rain chances increasing during the afternoon from west to 
east as a mid-level warm front approaches from the west-southwest. 
The longwave trough becomes cutoff over northern New England and 
southern Quebec on Thursday, then slowly shifts southeast toward the 
Gulf of Maine on Friday. As the mid-level low and surface low become 
vertically stacked, unsettled conditions are likely to persist into 
Thursday, with gradual improvement by Friday as surface high 
pressure builds in from the southwest and ridging develops from the 
west.

This system could bring beneficial rainfall. Global ensembles 
indicate moderate probabilities for 0.5"+ of rainfall, with ECMWF 
and Canadian ensembles between 60 and 80 percent, while the GEFS is 
slightly lower at 40 to 60 percent. Another way to view this: the 
25th percentile across these ensembles suggests 0.20 to 0.40 inches 
of total rainfall, while the 75th percentile ranges from 0.50 to 
1.00 inches. Still, there is plenty of time to refine details. 
Temperatures mid to late week remain below normal, with afternoon 
highs in the lower to middle 60s Wednesday and Thursday, and mid to 
upper 60s by Friday, assuming the cutoff low shifts east of the 
region and ridging develops. If the cutoff low lingers, another 
cooler day is possible.

KEY MESSAGE 3...Warmer weekend, lower confidence in sensible weather 
details.

Upper trough exits and heights rise heading into next weekend, 
supporting above-normal temperatures with highs into the 70s. 
Confidence remains lower regarding precipitation timing due to 
potential embedded shortwaves, but overall trends favor mainly dry 
conditions with only low-probability scattered showers.

&&

.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...High confidence.

VFR. -RA exits Cape Cod and the Islands by 15z. WNW winds less 
than 10 kts, except a few gusts around 20 kts along the leading
edge of the rain.

Tonight...High confidence.

VFR. Light NW to NNW winds 5 to 8 kt, with locally calm conditions 
possible in sheltered interior locations.

Tuesday...High confidence.

VFR. Light NW flow. Sea breeze development possible after 15Z along 
eastern MA coastal terminals.

KBOS Terminal...High confidence in TAF.

VFR prevailing outside of any brief early morning -RA potential. Sea 
breeze development possible after 15Z on Tuesday. 

KBDL Terminal...High confidence in TAF.

VFR.

Outlook /Tuesday Night through Friday/...

Tuesday Night: VFR. 

Wednesday: Mainly VFR, with local MVFR possible. Breezy. Chance
SHRA.

Wednesday Night through Thursday: Mainly MVFR, with local IFR
possible. Breezy. SHRA, slight chance TSRA, patchy BR.

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

Friday: VFR. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today through Tuesday...High confidence.

Residual elevated seas across the southern outer waters, generally 4 
to 6 ft, supporting continued Small Craft Advisories into late 
morning to early afternoon. A cold front moves offshore today with 
isolated showers possible over the southern outer waters. Winds 
shift from SW to NW this morning with brief gusts 20 to 25 kt 
possible. Winds and seas diminish tonight into Tuesday. Seas subside 
to 2 to 4 ft with light N winds generally less than 10 kt. Sea 
breeze development is possible Tuesday late morning into afternoon 
along nearshore waters.

Outlook /Tuesday Night through Friday/...

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

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

Wednesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas locally approaching 5 ft. Chance of
rain showers, patchy fog. 

Thursday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of seas approaching 5 ft. Rain showers, patchy
fog. 

Thursday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Chance of rain showers, patchy fog. 

Friday: Winds less than 25 kt. Seas up to 5 ft. Slight chance
of rain showers, patchy fog. 

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 PM EDT this afternoon for 
     ANZ254>256.

&&

$$

DISCUSSION...Dooley
AVIATION...Dooley/McMinn
MARINE...Dooley