Lexington Weather

Lexington, Massachusetts, USA

49°F

10/6/2024 4:23am

Lexington Conditions: Clear
Temperature: 48.9°F / 9.4°C
Dew Point: 43.7°F
Relative Humidity: 82%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 30.10 in Steady
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 291723
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
123 PM EDT Sun Sep 29 2024

.SYNOPSIS...
High pressure over the region will keep southern New England mainly 
dry through the start of next week. The next chance of rain arrives 
Tuesday night into Wednesday as a cold front moves through the 
region. High pressure will bring a return to dry and seasonable 
weather later in the week.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
High pressure drops south over SNE this afternoon, but skies will 
remain mostly cloudy to overcast.  Due to weak surface winds and 
minimal boundary layer mixing, the marine stratus cloud deck that 
moved in overnight will be slow to lift and break up today.  Once it 
does break up by the afternoon, more mid to upper-level cirrus 
clouds move in with the upper level cut off low still stalled to the 
south.  With thick cloud cover around all day, highs will only top 
out in the upper 60s to low 70s in spots.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM MONDAY/...
Mid to upper-level cirrus clear briefly overnight, setting up the 
stage for good radiation cooling and radiational fog to form.  Lows 
should drop into the low 50s to upper 40s in spots. Dewpoints will 
also be in the low to mid-50s near the south coast.  With winds 
turning more ESE, a low-stratus deck/fog bank could form overnight 
and last in the mid-morning hours. 

High pressure retreats north as an upper-level ridge passes to the 
north of northern New England.  This causes winds to turn back 
onshore from the ENE.  After low-level cloud cover and fog burn off 
again in the morning, mid to high-level cirrus builds back in, 
leaving skies mostly cloudy again. Guidance has trended warmer 
Monday afternoon into the mid to upper 70s. However, 850mb temps 
drop from +11C to +8C, and onshore flow should keep temps cooler 
than guidance.  Decided to use the 25th percentile NBM for temps, 
which keep highs in the upper 60s to low 70s, with mid-70s possible 
in the CT River Valley.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Highlights...

* Mostly dry & pleasant weather continues through next week.

* First chance of rain showers comes Tue night thru Wed night but 
  coverage is sporadic and a washout isn't expected. 

* Slight chance of rain returns around next weekend but confidence 
  is low. 

Details...

The forecast for Tue-Sat is largely dry, with scattered rain showers 
possible Tue night-Wed night bookended by dry weather. Helene's 
remnants will slowly move east off the Mid-Atlantic coast on Tuesday 
into Wednesday but high pressure extending from Nova Scotia will 
push the system far south enough to keep showers associated with it 
offshore. However, with low level flow around the high and saturated 
low levels, it will be cloudy and some drizzle is possible. The more 
robust rain chances accompany a cold front and mid level trough that 
swings through mid week. However, the best forcing is removed to the 
north and west so coverage of showers should be more hit and miss 
with the best chance over northwest MA. 

Starting Thursday drier zonal flow arrives with surface high 
pressure. The next feature to focus on will be a subtle shortwave 
that rotates through the mid level flow which may bring rain 
chances on Saturday before high pressure returns. However, 
confidence is low; EPS ensemble probabilities indicate a 50-60% 
chance of rain on Saturday while the GEFS is less enthused with only 
a 30-40% chance. Stay tuned.

&&

.AVIATION /18Z SUNDAY THROUGH THURSDAY/...
Forecast Confidence Levels:

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

Through 00z...High confidence. 

Mainly dry. MVFR trending to VFR late afternoon. Winds are east to 
northeast 5 to 10 knots. 

Tonight...Moderate confidence.

VFR trending MVFR after 08z, have held off on lower CIGs at this 
time, but low chance of this occurring mainly in elevated terminals 
like KORH. Ground fog possible across the interior. Winds are light 
and variable to calm.

Tomorrow...Moderate confidence. 

MVFR to start, trending VFR after 15z. East to northeast winds 5 to 
10 knots. 

Tomorrow Night...Moderate confidence. 

MVFR. Winds northeast less than 5 knots. 

BOS TAF...Moderate Confidence in TAF.

MVFR ceilings linger through 19z with improvement to VFR 
shortly afterwards. Lower ceilings return overnight, trending 
MVFR around 08z through 15z Monday. VFR CIGs after 15z through 
Monday afternoon. East to northeast winds less than 10 knots 
rest of today and tomorrow, will have near calm winds overnight.

BDL TAF...Moderate Confidence in TAF.

MVFR ceilings linger through 19z with improvement to VFR 
shortly afterwards. Lower ceilings return overnight, trending 
MVFR around 08z through 12z Monday. May have patchy ground fog 
predawn. VFR CIGs after 12z through Monday afternoon. East to 
northeast winds less than 10 knots rest of today and tomorrow, 
will have near calm winds overnight.

Outlook /Monday Night through Thursday/...

Monday Night: VFR. 

Tuesday: Mainly VFR, with local MVFR possible. 

Tuesday Night: Mainly VFR, with local IFR possible. 

Wednesday: Mainly VFR, with local MVFR possible. Slight chance
SHRA.

Wednesday Night through Thursday: VFR.

&&

.MARINE...
Forecaster Confidence Levels:

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

Today through Monday...High confidence. 

Marginal small craft waves continue in offshore southern waters this 
morning before dissipating this afternoon.  Light and variable winds 
today with seas 2-4ft.  Winds return to the NE on Monday and remain 
light. Seas drop to 1-3 feet Monday.

Outlook /Monday Night through Thursday/... 

Monday Night: Winds less than 25 kt. 

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

Tuesday Night through Wednesday: Winds less than 25 kt. Seas up
to 5 ft. Slight chance of rain showers. 

Wednesday Night through Thursday: Winds less than 25 kt. Areas
of seas approaching 5 ft.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

SYNOPSIS...BW/KP
NEAR TERM...KP
SHORT TERM...KP
LONG TERM...BW
AVIATION...BW/Dooley
MARINE...BW/KP