Lexington Weather

Lexington, Massachusetts, USA

56°F

6/9/2023 8:34pm

Lexington Conditions: Clear
Temperature: 55.8°F / 13.2°C
Dew Point: 54.1°F
Relative Humidity: 94%
Wind: Calm, 10-min avg: Calm, gust: None
Barometer: 29.68 in Steady
Visibility: 10 miles
Rain Today: 0.22 in

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 061848
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
248 PM EDT Tue Jun 6 2023

.SYNOPSIS...
Hit-or-miss showers and thunderstorms this afternoon and early 
evening. There will also be some near ground level smoke at times
as a result of the ongoing Canadian wildfires. While not as cool
as this past weekend, still expecting near to below normal 
temperatures with  mostly hit-or-miss showers during the daytime 
into early this weekend. No day should be a washout. Brief dry
weather with a warming trend for Sunday, before our weather
turns more unsettled with our next chance for widespread 
showers or thunderstorms either Monday or Tuesday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Lowered max temperatures slightly this afternoon, as the ongoing 
smoke appears to have cut into our insolation. Generally not enough 
to prevent all convection this afternoon, but enough to slow down 
the onset by a couple of hours. Radar and satellite data showed 
convection just getting started, so it is only a matter of time 
before scattered showers and thunderstorms impact portions of 
southern New England. Little to no shear and instability should mean 
convection dissipates shortly after sunset.

Near normal low temperatures expected.

&&

.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
Still no real changes to the overall synoptic pattern, with a mid 
level cutoff nearby and a surface low pressure lingering between 
northern New England and Maritimes. As such, a continued risk for 
diurnal showers during the afternoon and evening. The lift looks 
less robust, so coverage should be less. Near to below normal 
temperatures continue. 

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Highlights: 

* Increased daytime cloudiness with scattered hit-or-miss
  showers Thurs thru Sat, with clouds and showers diminishing 
  each evening. Temps cooler than normal, but they do warm each 
  successive day.

* Dry weather for Sunday with temps warming back to near or
  slightly above seasonable levels.
 
* Better opportunity for widespread rains early next week but it
  is still unclear which day(s) may have better rain chances.
  
Details:

Thursday through Saturday: 

Models and their ensemble means remain in good agreement on the  
overall pattern to close the workweek. A large/broad upper level
low over Nova Scotia/ME vicinity will continue to govern our
weather in this period, making slow eastward progress. With a 
cool pocket of air aloft (850 mb temps in the mid single digits 
C range) and some moisture around, expect diurnally-driven 
increases in cloud cover along with pop-up/hit-or-miss showers 
at scattered net coverage. It looks like instability will be too
limited to permit these diurnally driven cloudiness deepening 
to the point where thunder would be a possibility. Despite the 
showers around to dodge, there also will be several hrs of dry 
weather around. Expect cloud cover and showers to decrease each 
evening. Though a slow warming trend anticipated through late 
week into Sat, expect highs to run cooler than normal given the 
cool profiles aloft and "destructive" sunshine (e.g. heating 
driving increasing cloud coverage). Highs mainly upper 60s to 
mid 70s with lows in the lower to mid 50s.

The more noticeable change compared to prior forecasts is that
the upper low from late-weekend now looks to linger around for
another day, into Saturday. This seems reasonable as the
mid/upper level pattern remains blocky/slow-to-progress.
Conditions should be overall similar to Thurs and Fri, albeit
with slightly warmer temps. Have brought PoPs up into the
isolated to scattered shower range. 

Sunday: 

Sunday now looks to be a transition day back towards more
seasonable temperatures and dry weather as subsidence is induced
by shortwave ridging aloft, as the pesky upper level low finally 
moves east. Likely to be the pick of the weekend with
temperatures warming back to more seasonable levels (mid 70s to 
low 80s). Lows mainly in the 50s, and while humidity levels
increase it should still fall on the comfortable side.

Early Next Week:

Models and ensembles continue to show an evolving upper level
low digging into the OH Valley into the PA/western MD vicinity 
sometime early next week. Moisture levels increase more
significantly associated with a modest SSWly low-level jet. It
seems more likely that early next week (Mon/possibly Tue) offers 
a good chance for wetting rains with perhaps some garden variety
thunder too, as PWAT values rise to 1.2 to 1.5 inches. This is 
about one standard deviation above normal for early to mid June.
Have capped PoP for both Mon and Tue at high chance levels for 
now as there's a fair degree of solution spread as far as which 
day(s) may offer better rain chances. May see a slight decrease 
in temps owing to the increased cloud cover, and while not muggy
or oppressive, it may feel a touch more humid than conditions 
experienced more recently.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels:

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

Tonight...High Confidence.

Any scattered showers and thunderstorms will come to an end by  
early-mid evening. Otherwise, mainly VFR, but cannot rule out 
some marginal MVFR cigs working into northern MA overnight, 
along with a few spot showers.

Wednesday...High confidence. 

VFR but low prob of brief MVFR in isolated afternoon
-SHRA/-TSRA. Otherwise, dry weather in VFR conditions. 

Wednesday Night...High Confidence.

Mainly VFR, with areas MVFR, especially across the higher
terrain. 

KBOS Terminal...High Confidence in TAF. Generally VFR, then a 
few t-storms will develop this afternoon. Thinking is the bulk 
of them will be west of the terminal. We will also have to 
watch for areas of near ground level smoke at times, which may 
reduce visibility.

KBDL Terminal...High confidence in TAF. Main concern will be for
areas of near ground smoke that could briefly reduce vsbys 
today. We also will have to watch for the potential of a few 
t-storms developing this afternoon in the vicinity of the 
terminal.

Outlook /Thursday through Sunday/...

Thursday through Friday: Mainly VFR, with local MVFR possible.
Scattered SHRA.

Friday Night through Saturday: VFR. Scattered SHRA.

Saturday Night through Sunday: VFR. 

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Wednesday Night...High Confidence.

Low pressure lingers between northern New England and the
Maritimes. This results in a modest NW wind 10-20 kt and 
scattered showers/thunderstorms at times, mainly in the 
afternoon. Other than during brief shower/thunderstorm, good 
vsby expected. 

Outlook /Thursday through Sunday/...

Thursday: Winds less than 25 kt. Isolated rain showers. 

Thursday Night: Winds less than 25 kt. 

Friday: Winds less than 25 kt. Scattered rain showers. 

Friday Night through Saturday: Winds less than 25 kt. Isolated
rain showers. 

Saturday Night through Sunday: Winds less than 25 kt. 

&&

.TIDES/COASTAL FLOODING...
Astro tides remain high late tonight, 11.3 ft MLLW at Boston 
and 4.1 ft MLLW at Nantucket. Given less surge and wave action 
is expected than previous nights, waters levels and threat of 
minor flooding is also expected to be lower. Therefore, held off
on issuing any headlines.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Air Quality Alert until midnight EDT tonight for CTZ002>004.
MA...Air Quality Alert until midnight EDT tonight for MAZ002>024-
     026.
RI...Air Quality Alert until midnight EDT tonight for RIZ001>008.
MARINE...None.

&&

$$
SYNOPSIS...Belk/Loconto
NEAR TERM...Belk
SHORT TERM...Belk
LONG TERM...Loconto
AVIATION...Belk/Loconto
MARINE...Belk/Loconto
TIDES/COASTAL FLOODING...Staff