Lexington Weather

Lexington, Massachusetts, USA

56°F
6/9/2023 7:49pm 
  • Lexington Conditions: Mostly cloudy
  • Temperature: 56.3°F / 13.5°CWarmer 0.4°F than last hour.
  • Dew Point: 54.7°FIncreased 0.4°Fsince last hour.
  • Relative Humidity: 94
  • Wind: Calm, 10-min avg: Calm, gust: None
  • Barometer: 29.67 in Steady
  • Visibility: 10 miles
  • Rain Today: 0.22 in
  •   

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 070754
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
354 AM EDT Wed Jun 7 2023

.SYNOPSIS...
Sunshine returns Wednesday morning, especially across CT, RI and 
southeast MA. However, low pressure over the Maritimes moves 
westward into Maine, resulting in clouds building this afternoon 
along with scattered showers. Similar conditions expected
Thursday, Friday and Saturday, not a washout, but scattered 
afternoon showers each day. Temperatures will continue to run 
slightly cooler than normal. There will also be some near ground
level smoke at times this afternoon, as a result of the ongoing
Canadian wildfires. 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 /UNTIL 6 PM THIS EVENING/...

345 AM Update: 

Wednesday...

Sunshine to begin the day, especially across CT/RI and southeast MA. 
Across northern MA, lots of mid level clouds retrograding south from 
northern New England, as mid level low over New Brunswick moves 
westward into ME. Mid level warm air wraps cyclonically around this 
circulation (TROWAL) into northern MA this morning, along with the 
threat of some spotty light rain/sprinkles. Very atypical setup for 
early June.  Cyclonic flow and cold air aloft will result in another 
round of diurnal showers this afternoon. Although with the mid level 
low tracking closer to SNE, short waves will pivot cyclonically 
farther south and west around SNE. Therefore less synoptic scale 
lift and not quite as cold aloft will yield less instability. Hence, 
showers not as widespread as yesterday and given less instability, 
not expecting any strong storms along with threat of lightning much 
lower than Tue. Overall, many hours of dry weather especially this 
morning, then scattered afternoon showers. 

Slightly cooler than normal with highs in the upper 60s and lower 
70s. Modest NW wind 10-15 kt. Unfortunately another plume of smoke 
from Canadian wildfires advects across western-central MA and 
CT later today in NW flow aloft. 

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...

345 AM update...

Tonight...

Still under the influence of vertically stacked low over Maine. Any 
early evening diurnal showers taper off with sunset. Slightly cooler 
than normal temps continue with overnight lows in the 40s 
regionwide.  Partial clearing across CT/RI and southeast MA, but mid 
level clouds hanging tough across northern MA, as mid level warm air 
continues to circulate cyclonically around closed low over ME. Light 
NW winds. 

Thursday...

More clouds with mid level low nearly stationary over Maine. 
Cyclonic flow combined with cool air aloft will result in another 
round of diurnal scattered showers. Not a washout with many hours of 
dry weather, but will have to dodge a few afternoon showers. Cooler 
than normal with highs 65-70. Light and variable winds, but becoming 
onshore along the coast. 

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...

Highlights

* More diurnal showers and thunderstorms on Friday

* Warmer this weekend with showers on Saturday and drier weather on 
  Sunday

* Area of low-pressure may bring substantial rainfall to southern 
  New England early next week

Friday

The upper-level low that's been meandering over The Northeast this 
week will remain in the vicinity through at least Friday. Model 
guidance supports an upper-level cold pool associated with this low 
settling over southern New England on Friday afternoon. -21C temps 
at 500 hPa will support steep lapse rates through the column on 
Friday afternoon which will support diurnal showers and 
thunderstorms. Temperatures are forecast to be on the cooler side on 
Friday with highs unlikely to escape the 60s. Therefore, instability 
will be limited. Ensemble mean SBCAPE values on Friday afternoon 
continue to trend toward modest levels (200 to 300 J/Kg). Thus, the 
potential for any diurnal thunderstorms to become severe is low. The 
best thunderstorm chances will reside across the interior where the 
greatest instability/steepest lapse rates will reside. 

This Weekend

Upper-level low finally ejects east away from southern New England 
Friday night in to Saturday. This will allow westerly flow to advect 
warmer air over southern New England for the weekend. While temps 
will be a bit warmer on Saturday, cloud cover and diurnal showers 
will limit temperatures to the low 70s. Sunday appears to be the 
pick of the weekend as drier low-level air should support more sun 
than clouds and allow temps to get into the mid to upper 70s. Some 
spotty diurnal showers will be possible across western MA/CT 
but most areas should remain dry.

Next Week

Early next week an upper-level low will dig south over The Great 
Lakes before propagating east toward southern New England with more 
wet/unsettled weather. A surge of moisture over the region and 
robust forcing associated with this disturbance will bring an 
opportunity for substantial rainfall across southern New England 
during the Monday/Tuesday time frame. Details are vague at this time 
range, but the probability of 24 hour rainfall exceeding 1 inch 
between Monday and Tuesday is 20 to 30 percent across southern New 
England. These probabilities are derived from a grand ensemble of 
the GEFS,EPS, and GEPS.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels:

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

06z TAF Update: 

Thru 12z...high confidence. 

MVFR in areas of fog across southeast MA. Otherwise VFR and
mainly dry weather. However some spotty light rain/sprinkles
across northern MA to the VT/NH border. Light NW winds. 

After 12z...high confidence. 

VFR but scattered showers develop this afternoon regionwide,
with low risk of an isolated -TSRA. Another smoke plume likely
enters western MA/CT around midday, then spreads eastward into
RI and eastern MA late in the day. Vsbys may lower to 3 to 5
miles. Light NW winds, except SW along the south coast. 

Wednesday Night...High Confidence.

Mainly VFR with spotty light showers across northern MA. Light
NW winds. 

Thursday...high confidence. 

Mainly VFR but marginal MVFR across northern MA. Showers develop
during the afternoon. Light NW winds becoming locally onshore. 

KBOS Terminal...High Confidence in TAF. After 15z scattered
showers develop. Low risk of an isolated thunderstorm. NW winds
10-15 kt. Smoke may reduce vsby to 6 nm after 21z. 

KBDL Terminal...High confidence in TAF. VFR with scattered
showers developing this afternoon. Low risk of an isolated
thunderstorm. Smoke may reduce vsby to around 6 nm after 18z. 

Outlook /Thursday Night through Sunday/...

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

Friday: Mainly VFR, with areas MVFR possible. Chance SHRA,
isolated TSRA.

Friday Night: VFR. Chance SHRA.

Saturday: Mainly VFR, with local MVFR possible. Chance SHRA,
isolated TSRA.

Saturday Night through Sunday: VFR. Slight chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

345 AM update...

Low pressure over New Brunswick moves slowly west into Maine tonight 
and Thursday. Mainly dry weather prevails but can't rule out 
scattered diurnal showers near shore at times. 

Outlook /Thursday Night through Sunday/...

Thursday Night: Winds less than 25 kt. Slight chance of rain
showers. 

Friday through Saturday: Winds less than 25 kt. Chance of rain
showers. 

Saturday Night: Winds less than 25 kt. 

Sunday: Winds less than 25 kt. Slight chance of rain showers. 

&&

.FIRE WEATHER...

345 AM update...

Latest model simulations have the next plume of smoke from
Canadian fires entering western-central MA into CT this 
afternoon, then into RI and eastern MA this evening. Vsbys may
drop to 3-5 miles at times along with the smell of smoke. 

&&

.TIDES/COASTAL FLOODING...

345 AM update...

Astro tides remain high (11.1 ft at Boston and 4 ft at Nantucket) 
and combined with residual surge, very minor coastal flooding took 
place overnight. We may need to extend the coastal flood advisory 
into Thursday. 

&&

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

&&

$$
SYNOPSIS...Nocera/RM
NEAR TERM...Nocera
SHORT TERM...Nocera
LONG TERM...RM
AVIATION...Nocera/RM
MARINE...Nocera/RM
FIRE WEATHER...Nocera
TIDES/COASTAL FLOODING...Nocera
      

Other recent Area Forecast Discussions

Fri Jun 9, 7:00pm EDT

Fri Jun 9, 4:06pm EDT

Fri Jun 9, 2:18pm EDT

Fri Jun 9, 9:59am EDT

Fri Jun 9, 7:07am EDT

Fri Jun 9, 7:03am EDT

Fri Jun 9, 3:44am EDT

Fri Jun 9, 1:53am EDT

Thu Jun 8, 7:23pm EDT

Thu Jun 8, 3:51pm EDT

Thu Jun 8, 1:53pm EDT

Thu Jun 8, 9:25am EDT

Thu Jun 8, 7:20am EDT

Thu Jun 8, 6:57am EDT

Thu Jun 8, 3:57am EDT

Thu Jun 8, 2:24am EDT

Wed Jun 7, 10:17pm EDT

Wed Jun 7, 7:46pm EDT

Wed Jun 7, 3:36pm EDT

Wed Jun 7, 1:55pm EDT

Wed Jun 7, 10:29am EDT

Wed Jun 7, 7:12am EDT

Wed Jun 7, 2:16am EDT

Tue Jun 6, 10:15pm EDT

Tue Jun 6, 8:31pm EDT

Tue Jun 6, 2:48pm EDT

Tue Jun 6, 9:59am EDT

Tue Jun 6, 7:05am EDT

Tue Jun 6, 3:52am EDT

Tue Jun 6, 1:54am EDT

Mon Jun 5, 10:08pm EDT

Mon Jun 5, 7:44pm EDT

Mon Jun 5, 4:08pm EDT

Mon Jun 5, 2:01pm EDT

Mon Jun 5, 9:27am EDT

Mon Jun 5, 7:16am EDT

Mon Jun 5, 3:59am EDT

Mon Jun 5, 1:53am EDT

Sun Jun 4, 10:06pm EDT

Sun Jun 4, 8:22pm EDT

Sun Jun 4, 7:09pm EDT

Sun Jun 4, 3:56pm EDT

Sun Jun 4, 1:57pm EDT

Sun Jun 4, 10:37am EDT

Sun Jun 4, 6:58am EDT

Sun Jun 4, 4:09am EDT

Sun Jun 4, 1:50am EDT

Sat Jun 3, 10:16pm EDT

Sat Jun 3, 8:00pm EDT

Sat Jun 3, 2:00pm EDT

Sat Jun 3, 12:42pm EDT

Sat Jun 3, 9:20am EDT

Sat Jun 3, 7:12am EDT

Sat Jun 3, 4:14am EDT

Sat Jun 3, 4:12am EDT

Sat Jun 3, 1:56am EDT

Fri Jun 2, 9:58pm EDT

Fri Jun 2, 7:53pm EDT