Lexington Weather

Lexington, Massachusetts, USA

49°F

5/11/2024 8:30pm

Lexington Conditions: Clear
Temperature: 48.6°F / 9.2°C
Dew Point: 39.9°F
Relative Humidity: 72%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.83 in Steady
Visibility: 10 miles
Rain Today: 0.00 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 091926
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
326 PM EDT Thu May 9 2024

.SYNOPSIS...
High pressure to the north brings mainly dry and mild conditions 
this afternoon. Some showers are possible this evening into early 
Friday as low pressure tracks to the south, otherwise drier and 
cooler for much of Friday as NE winds develop. Cooler than normal 
this weekend with rain chances increasing Saturday night and Sunday, 
then milder temperatures return early next week but an unsettled 
weather pattern will continue.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...

IR satellite imagery shows a band of moisture moving in which has 
moved over the southern half of SNE this afternoon increasing 
cloudcover and allowing some very light returns to bloom on the 
radar mainly off shore. Overall the dry day will continue for most 
of the region thanks to some subtle mid level ridging and a drier 
airmass further north, but we will see some scattered showers moving 
into northeast MA this evening on cool NE flow. Not everyone in 
northeast MA will see a shower, and they will be transient in 
nature. 

The more widespread showers tonight will occur over the southern and 
western parts of the region as a subtle shortwave passes overhead 
providing enough synoptic lift acting on the ~1" PWAT plume to 
produce rain showers overnight, generally light (a few tenths to a 
few hundredths). 

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Tonight...

As mid level trough amplifies over the Gt Lakes, backing flow aloft 
will bring increasing moisture northward into SNE. However, there is 
uncertainty regarding how far north and east showers will get across 
SNE as best moisture will remain to the SW. Best chance for a period 
of rain tonight will be from western MA to RI closest to best 
moisture, with decreasing probs further NE into portions of eastern 
and NE MA.  

Lows will be in the 40s tonight, with increasing NE winds along the 
south coast and Cape/Islands as low pres moves off the mid Atlc 
coast. 

Friday...

Some lingering showers are possible Fri, especially across SW 
portions of SNE, but drier air will gradually move in from the north 
during the day as high pres builds south into eastern New Eng. This 
may lead to partial sunshine developing across portions of northern 
and eastern MA. NE flow will result in cooler temps Fri with highs 
mostly in the 50s, with some lower 60s possible in the CT valley.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...

The bulk of the rain exits by mid morning on Friday as drier air 
filters in around the high to our north. As the high builds in we'll 
see some breaks of sun, especially over north central and north 
eastern MA in closer proximity to the dry air. Temperatures will 
continue to be quite a bit cooler than normal for mid May thanks to 
persistent NE flow. Highs won't make it out of the 50s, save for the 
CT Valley which may just make it to the low 60s. 

Surface high pressure continues to push in from the north overnight 
keeping low pressure well offshore. So, even with a shortwave 
overhead, the column will be quite dry over SNE and most if not all 
of the wet weather looks to remain on the periphery of the region to 
the west and south overnight. Low temperatures will be several 
degrees cooler, in the upper 30s to low 40s. 

&&

.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
Forecast Confidence Levels:

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

18Z TAF Update:

This afternoon...Moderate confidence. 

VFR. N wind around 10 kt turning NE during the afternoon.

Tonight...Moderate confidence. 

MVFR cigs expanding westward across western and central SNE
terminals. Low prob for IFR. MVFR expected to stay out of
eastern MA terminals but confidence is only moderate. Scattered
showers developing, especially across western half New Eng. NE 
wind 5-15 kt.

Friday...Moderate confidence. 

Cigs improving to VFR from NE to SW as drier air works in from 
the N. A few showers possible, mainly from SW MA and CT to the 
south coast.

Friday night...moderate confidence. 

NE winds diminishing overnight. VFR except for marginal MVFR
cigs over the Cape and islands. 

KBOS TAF...Moderate confidence in timing of wind shift to NE.

KBDL TAF...High confidence in TAF today. 

Outlook /Saturday through Tuesday/... 

Saturday: VFR. Breezy. Slight chance SHRA.

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

Sunday: Mainly VFR, with local MVFR possible. Slight chance
SHRA, isolated TSRA.

Sunday Night: VFR. 

Monday through Monday Night: VFR. Breezy. Slight chance SHRA.

Tuesday: VFR. Breezy. Chance SHRA, isolated TSRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Friday night...

Northeast winds below 20 kt may increase with gusts 20-25 kt 
tonight into Fri, especially over south coastal waters as low 
pres tracks to the south. Seas build to near 5 ft over the 
eastern outer waters late tonight into Friday night. A SCA may 
be needed for eastern MA waters toward Saturday but conditions 
are marginal.


Outlook /Saturday through Tuesday/... 

Saturday through Sunday: Winds less than 25 kt. Seas up to
5 ft. Slight chance of rain showers. 

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

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

Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain
showers, isolated thunderstorms. 

&&

.TIDES/COASTAL FLOODING...
High astronomical tides coupled with onshore flow may result in some 
splashover/very minor coastal flooding during the overnight high 
tide cycle tonight. However, wind/waves do not appear high enough to 
result in a significant issue. The daytime high tides are lower and 
do not pose a threat for coastal flooding.

&&

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

&&

$$

SYNOPSIS...BW/BL
NEAR TERM...BW
SHORT TERM...BW
LONG TERM...KP
AVIATION...BW/BL 
MARINE...BW/BL 
TIDES/COASTAL 
FLOODING...