Old Res Weather

Lexington, Massachusetts, USA

35°F

2/16/2025 7:17pm

Lexington Conditions: Mist, Overcast
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: 1¾ miles
Rain Today: 0.01 in
UV Index: $VPuv None

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 180800
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
400 AM EDT Tue Aug 18 2026

.WHAT HAS CHANGED...
No significant changes.

&&

.KEY MESSAGES...

- Gradual clearing today with a low chance of showers in parts of
  the interior. Drier into Wednesday.

- Generally becoming unsettled once again towards the second 
  half of the week into the start of next week.

&&

.DISCUSSION...
KEY MESSAGE 1...Gradual clearing today with a low chance of 
showers in parts of the interior. Drier into Wednesday.

Low pressure continues to pull off to the east and northeast today, 
which will allow for slow clearing, developing from west to 
east. Onshore flow persists as this low pulls further away from 
the region, which will likely keep temperatures near the coasts 
slightly cooler in the 70s. The rest of southern New England 
may reach the low 80s, as that's where clouds should scatter 
out sooner. With the clearer conditions inland, it will also be 
less humid as winds shift more northwest. A spot shower or two 
cannot be entirely ruled out across much of central MA into RI, 
CT this afternoon. Tonight should be calm with patchy fog 
possible and lows in the 60s.

Zonal flow persists aloft into Wednesday as an upper level low 
tracks well to our north across the Hudson Bay. Some guidance does 
indicate some shortwave energy moving within the flow across the 
region later Wed into Thu which could lead to a spot shower or two, 
however the more favorable parameters remain to our north and west.

KEY MESSAGE 2...Generally becoming unsettled once again towards
the second half of the week into the start of next week.

A stronger shortwave within the flow aloft makes its way east 
heading into Thursday, bringing with it more favorable dynamics and 
moisture for showers. Discrepancies still remain regarding the 
wave's track across the ensemble and deterministic guidance, with 
the GEFS continuing to show higher probabilities for 24 hour 
rainfall of 0.1"+ extending into CT, SE MA, and RI while the ECMWF 
and Canadian ensembles continue to favor a more southern track. 
NAEFS guidance, notably, keeps the more anomalous moisture off to 
our south and east, though PWAT values reaching to around 1.5" are 
not out of the question.

Under the post-frontal airmass Friday with high pressure overhead, 
conditions will be drier overall. Temperatures will likely be in the 
low 80s and down to the mid 70s, particularly along the coasts where 
onshore winds will keep it slightly cooler. Conditions become 
unsettled once more, though, as we keep an eye on a deepening trough 
digging into the Great Lakes region towards the weekend period. 
Shortwaves moving along the boundary that may stall just off the 
east coast could bring chances for showers. Thunderstorms could be a 
possibility depending on if these waves could take advantage of 
daytime heat. More details will become apparent as we approach this 
timeframe.

&&

.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...

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

Through 12z...Moderate confidence

Pockets of IFR are continuing to develop across the region, 
with some areas reaching LIFR. Notably, coastal terminals have 
hit this sooner. Light E to NE winds continue over more coastal
terminals with calm conditions persisting over the interior 
terminals.

Tuesday...Moderate confidence (ceilings)

MVFR to IFR conditions to start, with improvement to VFR from west 
to east between 17Z and 20Z. Improvements for terminals further
east may be slower and may only top out to MVFR based on
guidance, though VFR by 00z is a possibility for Cape/Islands
terminals. Light N winds become more NW during the afternoon for
the interior terminals, while onshore NE/E winds continues for
eastern terminals, generally at 5-10 kt. Higher winds above 10
kt are possible for ACK.

Tuesday Night...Moderate confidence. 

VFR across the interior, though MVFR towards the Cape/Islands,
along with RI terminals, depending on how thick cloud cover
remains. Otherwise, SCT to FEW at lower ceilings. ACK could see
return of IFR conditions. Light NW to SW winds less than 10 kt
with patchy fog possible.

Wednesday...High confidence.

VFR. WSW winds over much of the region, more SSW over the
coastal areas all at 5-10 kt.

KBOS Terminal...Moderate confidence.

LIFR visby possible periodically early this morning through at
least 08z. Exact timing of improvements to VFR lower 
confidence, but more likely between 16-19Z. SCT MVFR decks 
possible through the afternoon. Winds NE becoming E in the 
afternoon 7-10 kts. 

KBDL Terminal...Moderate confidence.

MVFR conditions have just moved in to the terminal and are
expected to continue through the rest of tonight into the
mornings hours. Periods of IFR cannot be entirely ruled out for
the early morning hours. Chance of fog remains.

Outlook /Wednesday Night through Saturday/...

Wednesday Night: VFR. 

Thursday: VFR. Slight chance SHRA, slight chance TSRA.

Thursday Night through Friday Night: VFR. Slight chance SHRA.

Saturday: VFR. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Through Wednesday Night...Moderate confidence.

Low pressure continues to shift farther off to the east. Seas
diminish more to 2-4 ft across the coastal and nearshore waters.
Ocean waters off to the east may take longer to drop off as they
may get to around 5-6 ft heading into tonight. By Wednesday,
seas fall to 2-3 ft across all waters. Winds through this period
remain generally under 15 kt outside of occasional gusts in the
afternoons. More N winds shift W, then S tonight, then more SW
by Wednesday night.

A higher rip current risk is expected for east-facing
beaches where a Rip Current Statement is in effect from 8 AM 
this morning through 8 PM tonight.

Outlook /Wednesday Night through Saturday/...

Wednesday Night: Winds less than 25 kt. 

Thursday: Winds less than 25 kt. Slight chance of rain showers.

Thursday Night: Winds less than 25 kt. Chance of rain showers,
slight chance of thunderstorms. 

Friday through Saturday: Winds less than 25 kt. Chance of rain
showers. 

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...High Risk for Rip Currents from 8 AM EDT this morning through this 
     evening for MAZ007-015-016-019-022-024.
RI...None.
MARINE...None.

&&

$$

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