Lexington Weather

Lexington, Massachusetts, USA

50°F

10/6/2024 2:49am

Lexington Conditions: Clear
Temperature: 50.4°F / 10.2°C
Dew Point: 44.1°F
Relative Humidity: 79%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 30.11 in Steady
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Lexington, MA

        
000
FXUS61 KBOX 060536
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
136 AM EDT Sun Oct 6 2024

.SYNOPSIS...
A cold front moves through Southern New England late Sunday 
night into Monday, bringing a period of rain showers. This cold 
front will usher in a cooler, fall-like weather pattern for the 
rest of the work week.

&&

.NEAR TERM /THROUGH TODAY/...

930 PM Update...

Radiational cooling has sprung into action after sunset with
temperatures falling into the upper 40s and low 50s at our
typically radiative sites. Urban heat islands, like Boston and
Hartford, were grasping the the last 60s of the evening at the
top of the hour ob, but expecting they too will fall below that
mark in the next hour or so. With dewpoints in the upper 30s to
low 40s across the interior, temps have a ways to fall under
clear skies tonight. 

Previous Update...
Daytime cu is expected to linger before clearing out tonight. 
Radiational cooling with dew points reaching the lower 40s will help 
bring lows down to the 40s, particularly towards the interior. Lows
along the coast and within the urban heat islands of Providence
and Boston could reach the lower 50s, but not below that just 
yet.

&&

.SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/...

Weak high pressure provides relatively tranquil weather to 
start Sunday, which then continues into first part of Sunday 
night. 

Then looking at the combination of a cold front and a mid level 
shortwave to provide our next chance for showers late Sunday night 
into Monday. This front should still be lingering near the east 
coast of MA by Monday evening, so thinking unsettled conditions will 
be more the rule Monday. Moisture is quite a bit deeper than the 
past few systems that have come trough southern New England. This 
should be a greater chance for rainfall than we have had in a while.

There is a low risk for isolated thunderstorms late Sunday Night 
into Monday. Not the best environment expected, with meager mid level 
and poor low level lapse rates. Will need to monitor this potential 
with later forecasts, but severe weather is not anticipated.

Near to slightly below normal temperatures expected during this 
portion of the forecast.

&&

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

Highlights:

* Dry and cooler weather is expected for much of next week. 

* Cold overnights may lead to areas of frost, mainly across northern 
  Massachusetts Tuesday night. With frost possibly more widespread 
  on Wednesday.

There are no significant changes to the extended section of the 
forecast. The coming week features dry and noticeably lower 
temperatures. The only active weather is Monday night through 
predawn Tuesday with the passage of a cold front, during this time 
scattered showers are still possible across Rhode Island and eastern 
Massachusetts. Given this is 48 to 60 hours out, timing could sway 
by a few hours. 

Behind the departing front, surface high builds to the northwest of 
southern New England on Tuesday though Friday. This provides quiet 
weather conditions for the rest of the work week. Aloft, there is an 
anomolous mid-level low pressure system sitting to our north and 
ushers cooler airmass through northwest flow into southern New 
England. True taste of fall with daily highs Tuesday through Friday 
between the upper 50s and lower 60s, as for nighttime lows, 30s and 
lower 40s Tuesday night through Thursday night. Did adjust minimum 
temperatures by blending in the cooler 25th percentile of the NMB on 
those nights because of the potential for effective radiation 
cooling, clear sky and light winds. These conditions could lead to 
the first frost of the season for some areas in northern 
Massachusetts. 

It is worth noting, average first frost for northern Massachusetts 
is around the 1st of October, since we are past is date, there would 
be no headlines issued. Though, areas outside of the east slopes of 
the Berkshires and northern Worcester Hills, our frost and freeze 
program remains active through the 11th of October. Potentially
could have lows the morning of October 10th around the mid-30s.
Either way, if you have fall mums sitting outside, be mindful 
of the cooler weather that is upon us this week.

As previously mentioned, expect a mainly dry week ahead. While there 
will be shortwave energy pivoting around the mid-level low to our 
north, PWATs are VERY low, mainly below 0.5", but at times less than 
0.25". Given lack of sensible moisture, not expecting any rainfall. 

As for an early look at the upcoming holiday weekend, Saturday is 
dry with seasonable high temperatures in the upper 60s to 70F. The 
second-half of the weekend there remains uncertainty amongst model 
guidance, but as that is more than 7 days out, there is still time 
for things to change.

&&

.AVIATION /05Z SUNDAY THROUGH THURSDAY/...

Forecast Confidence Levels:

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

06z TAF Update...

Today...High Confidence.

Mainly VFR. However...some marginal MVFR ceilings may roll in
off the ocean this morning and impact parts of the Cape and
Islands for a time today. Lower risk these marginal MVFR
ceilings flirt with the BOS terminal...but will have to monitor. 
Light N winds shifting to the south this afternoon...but with 
sea breezes along portions of the immediate coast.

Tonight and Monday...High Confidence this evening with moderate
confidence overnight into Monday. 

VFR conditions dominate this evening. MVFR-IFR conditions should
overspread most areas from west to east between 06z to 12z Mon 
along with widespread showers. This process may be 1 to 3 hours 
later towards the Cape and Islands. Widespread showers with the
risk for an embedded t-storm or two will be possible on Mon. 
The back edge of the showers should be east of the CT River 
Valley by Mon mid afternoon and near the I-95 corridor by early
Mon evening. Conditions to improve to VFR during the afternoon 
and approach the I-95 corridor by early evening. S winds 5-10 
knots Mon am should shift to the NW across interior southern New
England during Mon pm behind the cold frontal passage.

KBOS TAF...Moderate confidence in TAF.

Generally VFR conditions expected today. However...a period of
marginal MVFR ceilings may flirt with the terminal for a brief
time today...depending on how far west clouds are able to back 
in off the ocean. N winds shift to the E by early afternoon 
around 10 knots.

KBDL TAF... High Confidence in TAF. 

VFR into this evening.

Outlook /Monday Night through Thursday/...

Tuesday Night through Wednesday: VFR. 

Wednesday Night through Thursday Night: VFR. Breezy. 

Friday: Breezy.

&&

.MARINE...
Forecaster Confidence Levels:

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

Saturday...High Confidence

Scattered showers possible early Saturday morning into Saturday
mid-day, though showers may linger across the eastern outer
waters into Saturday evening. Winds shift behind passing front
to the NW Saturday morning; winds less than 25 kts. Waves 2-4 
ft.

Saturday Night...High Confidence

Winds 10-20 kts with higher winds confined to the outer waters.
Seas grow to 5-6ft overnight tonight, prompting the issuance of
a SCA from 06Z and beyond. 

Sunday... High Confidence 

Winds less than 25kt but seas across the outer waters continue
to range from 4-6ft. SCA continues for the outer waters through
the day Sunday, and beyond. 

Outlook /Monday Night through Thursday/...

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

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

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

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 AM EDT Tuesday for ANZ250-254-255.
     Small Craft Advisory from 4 AM Monday to 8 AM EDT Tuesday for 
     ANZ256.

&&

$$

SYNOPSIS...Belk/Dooley/Hrencecin
NEAR TERM...Hrencecin/KS
SHORT TERM...Belk
LONG TERM...Dooley
AVIATION...Frank/Dooley
MARINE...Belk/Dooley/Hrencecin