Lexington Weather

Lexington, Massachusetts, USA

56°F

9/29/2023 4:37pm

Lexington Conditions: Rain, Mist, Overcast
Temperature: 55.9°F / 13.3°C
Dew Point: 54.9°F
Relative Humidity: 96%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 30.21 in Steady
Visibility: 1½ miles
Rain Today: 0.51 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 291941
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
341 PM EDT Fri Sep 29 2023

.SYNOPSIS...
Low pressure south of New England will bring continued rain to 
southern New England into Saturday. High pressure builds into the 
region Sunday through much of the upcoming week, resulting in dry 
weather with a warming trend.

&&

.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
Axis of moderate to heavy rainfall continues to impact much of 
western MA/CT. Peak rainfall rates thus far are averaging 0.25-
0.50"/hr. Radar rainfall rates ha ve been overdone in western 
MA due to bright banding. We've had reports of 2-3 inches of 
rain in western half of Hartford county and an area flood 
warning was issued due to a few fast rising streams which have 
risen above flood stage, including North Branch Park River and 
the Bunnell Brook. Low level easterly flow is enhancing rates 
along the east slopes of the terrain in far western Hartford 
county near the Litchfield county line where localized 3-4 inch
reports have been recieved. 

The heaviest rainfall will remain focused in western MA/CT into this 
evening as not much change in the orientation and location of the 
low level jet and surface boundary. Additional rainfall of 1-2 
inches is possible through tonight, especially from western Hartford 
county northward into the east slopes of the Berkshires. Rainfall 
rates will average up to 0.10-0.25"/hr but up to 0.50"/hr in the 
heaviest rain. Minor street flooding and minor small stream flooding 
is likely, especially in Hartford county and portions of western MA. 
Will also have to watch the Farmington river for possible flooding. 

As the upper low moves approaches the mid Atlc coast late tonight, 
the surface shifts south of the benchmark while the low level jet 
becomes more easterly and focused south of the Cape/Islands. This 
will shift the axis of heavier rainfall south of the Mass Pike and 
particularly across SE New Eng late tonight. Rain will remain light 
across NE MA further removed from the low level jet and deep 
moisture plume. 

&&

.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Saturday...

The mid/upper low sets up south of New Eng with the comma 
head/trowal bringing periods of rain to SNE in the morning, 
especially across RI and SE MA where the rain may be heavy at times 
near the axis of the low level jet. Still some uncertainty on the 
strength and location of the low level jet which will determine the 
extent of heavy rainfall and whether it remains to the south or gets 
into SE New Eng. Rain will be ending in the interior and northern MA 
late morning and especially afternoon as pronounced mid level drying 
moves in from the N. However, the rain will continue for much of the 
day closer to the south coast. Gusty NE winds expected over 
Cape/Islands. Highs mostly 60-65, perhaps some upper 60s CT valley 
in northern MA if some sun can develop in the afternoon.

Saturday night...

Mid level low slowly moves offshore as it drifts SE with gradual 
improving conditions. Clearing will develop in western New Eng and 
gradually push to the SE. However, showers could linger in SE New 
Eng for the first half of the night, especially Cape/Islands. Lows 
mid/upper 40s interior to low to mid 50s SE New Eng. 

&&

.LONG TERM /SUNDAY THROUGH FRIDAY/...
Key Points:

 * Prolonged stretch of dry weather with a warming trend.

Confidence continues to increase on having several days of dry 
weather next week along with a warming trend. Ensembles are in very 
good agreement that upper trough moves offshore Sunday and allows 
ridging to build across eastern third of country much of next week. 

From there, although there are timing differences, ensembles agree 
in digging trough into northern Plains or Tennessee Valley by the 
end of the week. This will bring increasing chances for showers 
Friday as cold front approaches from Great Lakes, but if trough ends 
up slowing down, dry weather could last through Friday.

&&

.AVIATION /20Z FRIDAY THROUGH WEDNESDAY/...
Forecast Confidence Levels:

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

Through Tonight...Moderate confidence.

MVFR to IFR conditions will persist in rain. Heaviest rain in
western CT/MA into this evening will gradually shift to SE New
Eng late tonight. 

Saturday...Moderate confidence.

IFR improving to MVFR then VFR from NW to SE late morning
through the afternoon as rain gradually ends. But MVFR 
persisting through the day across eastern MA/RI where rain is
expected to continue. NE winds 10-15 kt, with gusts to 25 kt
Cape/Islands. 

Saturday night...Moderate confidence.

Mainly VFR in the interior, but MVFR cigs across eastern MA.
Mainly dry, but showers may linger across Cape/Islands. N winds
gusts to 25 kt over ACK.

KBOS Terminal...Moderate confidence in TAF. Kept cigs at 1000 ft
through tonight, but may see a period of IFR.  

KBDL Terminal...Moderate confidence in TAF, mainly due to timing
of improving conditions on Sat.  

Outlook /Sunday through Wednesday/... 

Sunday: VFR. Breezy. 

Sunday Night: VFR. 

Monday: VFR. Breezy. 

Monday Night through Wednesday: VFR. 

&&

.MARINE...
Forecaster Confidence Levels:

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

Persistent NE winds through Sat night. Low level jet will bring 
increasing winds late tonight into Sat night as low pres sets up 
south of the 40N/70W benchmark. Gusts 25-30 kt over the southern 
waters, but gusts to 20 kt over NE MA waters. SCA will continue.

Outlook /Sunday through Wednesday/...

Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of rough seas. Slight chance of rain showers. 

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

Monday Night through Tuesday: Winds less than 25 kt. Areas of
seas approaching 5 ft. 

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 2 AM Saturday to 8 AM EDT Sunday for 
     ANZ232>234-250.
     Small Craft Advisory until 8 AM EDT Sunday for ANZ235-237-
     254>256.

&&

$$
SYNOPSIS...KJC/JWD
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...JWD
AVIATION...KJC/JWD
MARINE...KJC/JWD