Lexington Weather

Lexington, Massachusetts, USA

85°F
8/8/2022 7:24pm 
  • Lexington Conditions: Clear
  • Temperature: 85.3°F / 29.6°CColder 2.1°F than last hour.
  • Dew Point: 73.9°FIncreased 0.7°Fsince last hour.
  • Relative Humidity: 69%Increased 6.0% since last hour.
  • Wind: Wind from SW SW 1 mph, 10-min avg: 2 mph, gust: 12 mph
  • Barometer: 29.80 in Steady
  • Visibility: 10 miles
  • Rain Today: 0.00 in
  •   
Southeast Middlesex County, MA - Heat Advisory
 - SEE ALL NEARBY ALERTS -

Area Forecast Discussion
for Boston / Norton, MA

        
000
FXUS61 KBOX 080153
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
953 PM EDT Sun Aug 7 2022

.SYNOPSIS...
Heat and humidity will continue to be the main weather story 
well into next week. Heat Advisories continue through Monday.
A cold front will bring a better chance of thunderstorms on
Tuesday. The front will stall just south of the area Wednesday 
with low pressure passing along it, which might bring welcome
rain Wednesday into Thursday. While the heat will break on 
Wednesday, the humidity won't ease up in a meaningful way until 
Friday.

&&

.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
No major changes to the forecast this evening. Thought the last
few runs of the HRRR had the correct idea for convective trends
this evening. This was also supported by regional radar data.
Only minor tweaks to temperatures and dew points for the
overnight hours. Yet another muggy night in store for southern
New England.

Previous Discussion...

Forecast is on track this afternoon, with cumulus bubbling
across southern New England but only sparse showers so far 
which continue to pulse up and quickly collapse. As we go 
through the afternoon the coverage of showers and storms may 
increase, mainly along and north of the MA pike. Mesoanalysis 
shows 2000-2500 J/kg of CAPE but with no shear and lackluster 
mid level lapse rates which should keep any thunderstorms of the
garden-variety. With sunset and loss of diurnal heating storms 
will rapidly diminish in coverage leaving mostly clear skies, 
save for the south coast where low level moisture will once 
again bring the threat of low stratus to the Cape and islands. 
Low temps will be quite warm owing to the very moist airmass, in
the mid 70s.

&&

.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Monday we rinse and repeat, as has been the story for days now. The 
hot and humid airmass remains overhead  with little change to speak 
of. SW winds continue and advect in marginally warmer air in the low 
levels (850 mb temps increase from 18C to 19-20C) so temperatures 
will be a few degrees warmer, especially in the Connecticut Valley. 
Highs in the low to mid 90s and dewpoints in the mid 70s mean 
another day of heat indices at or above 100F. Instability will once 
again be high (CAPE >1500 J/kg) with poor shear (though a bit higher 
than Sunday). Not expecting a severe threat with any storms that pop 
up on Monday afternoon and evening. Any convection that does fire 
will die down after sunset leaving a dry forecast for the overnight 
hours. Increasing winds late in the day and overnight will take the 
edge off, especially along the south coast and offshore.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
Highlights...

* Hot and humid Tuesday with a slow moving cold front bringing
  the likelihood of afternoon and evening thunderstorms.

* Low pressure moving along the front just south of New England
  may bring a period of welcome rain Wednesday into Thursday.

* Heat will break on Wednesday, but humidity won't return to
  comfortable levels until Friday.

Tuesday and Tuesday night...

Models are now more in line with the cold front sagging
southward across our region Tuesday and Tuesday night. Ahead of
the front, high temperatures are forecast to again rise to
between 90 and 95 degrees, with heat indices reaching 96-102,
highest in northern CT and in RI and interior southeast MA. 

The front will provide the focus for more numerous showers and
thunderstorms than today or Monday. CAPE will be moderately 
high, but there is little in the way of shear to support 
organized severe storms. With that much heat and humidity, there
undoubtedly will be a isolated severe storm that pops up,
however. Also, there could be localized street flooding with 
any slow-moving storms.

Wednesday and Thursday...

The front slips just south of New England then stalls, with
weak low pressure traveling along it. We will have much cooler
northeast wind flow, with highs only from 76-83, bringing an 
end to the heat wave. Ensembles signal a decent chance of a
much-needed rather widespread soaking rainfall from Wednesday 
into Thursday, with the highest probabilities Wednesday night. 
There could be an isolated rumble of thunder, mainly along the 
south coast. Rainfall totals could approach 1 to 1.5 inches in 
some areas. Tough to forecast this when we've been so dry...will
fine tune as time goes on.

Friday through Sunday... 

Significant model differences Friday through Sunday.
Ensembles still show clearing skies Friday and mainly dry 
weather through the weekend. But operational ECMWF shows strong 
upper low cutting off to our west, becoming negatively tilted, 
and spawning another coastal low that brings additional rain 
chances here Friday and Saturday. GFS also has upper low 
developing over SNE with coastal low and rain chances in 
easternmost SNE Saturday. In any case, cooler weather prevails
through the weekend. Stay tuned for more revisions in upcoming
forecasts for this period.

&&

.AVIATION /02Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels:

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

Tonight...Moderate Confidence. 

Mainly VFR. Areas of IFR in stratus expected towards the south 
coast late. Light SW winds.

Monday...Moderate Confidence.

Mainly VFR. IFR stratus more likely to persist towards the 
south coast around daybreak. Brief periods of MVFR in any
afternoon showers or thunderstorms. SW winds 5-10 kt with gusts
up to 20 kt.

Monday night...High confidence. 

VFR. SW winds 5-15 kts gusting to 25 kts for southeast MA. 

KBOS...Moderate confidence in TAF due to uncertainty as to
whether any TSRA makes it to the terminal this afternoon.
Greatest risk, though still low, is no sooner than 20z.

KBDL...Moderate confidence in TAF due to uncertainty as to
whether any TSRA makes it to the terminal this afternoon.
Greatest risk, though still low, is no sooner than 19z. 

Outlook /Tuesday through Friday/...

Tuesday: Mainly VFR, with areas MVFR possible. Breezy. Chance
SHRA, chance TSRA.

Tuesday Night: Mainly MVFR, with areas IFR possible. Chance
SHRA, chance TSRA.

Wednesday: Mainly MVFR, with areas IFR possible. Chance SHRA,
isolated TSRA.

Wednesday Night: Mainly MVFR, with local IFR possible. SHRA
likely.

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

Thursday Night: Mainly VFR, with areas MVFR possible. Slight
chance SHRA, isolated TSRA.

Friday: Mainly VFR, with areas MVFR possible. Slight chance
SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Through Monday night...High Confidence.

Tonight, SW winds 15-20 kt with gusts up to 25 kt. Seas increase 
to 5-6 ft on the southern waters tonight. Winds and seas
diminish some into Monday, with rough seas lingering across the 
outer coastal waters the longest. Winds and seas increase once 
again Monday evening and overnight. 

Outlook /Tuesday through Friday/... 

Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Local rough seas. Chance of rain showers, chance of
thunderstorms. 

Tuesday Night: Winds less than 25 kt. Areas of seas approaching
5 ft. Chance of rain showers, chance of thunderstorms. 

Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers, isolated thunderstorms. 

Wednesday Night: Winds less than 25 kt. Rain showers likely,
slight chance of thunderstorms. 

Thursday through Thursday Night: Winds less than 25 kt. Chance
of rain showers, isolated thunderstorms. 

Friday: Winds less than 25 kt. Slight chance of rain showers,
isolated thunderstorms.

&&

.CLIMATE...
Record Maximum Temperatures

August 7th:
BOS 98F - previously 98F [1924] (tied)
ORH 94F [1924]
PVD 95F - previously 95F [2001] (tied)
BDL 100F [1918]

August 8th:

BOS  96F  [1983]
ORH  94F  [1916]
PVD  95F  [1909]
BDL  98F  [2001]

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT Tuesday for CTZ002>004.
MA...Heat Advisory until 8 PM EDT Tuesday for MAZ002>023-026.
RI...Heat Advisory until 8 PM EDT Tuesday for RIZ001>007.
MARINE...Small Craft Advisory until 8 AM EDT Tuesday for ANZ231>235-237.
     Small Craft Advisory until 1 AM EDT Monday for ANZ236-250.
     Small Craft Advisory until 8 PM EDT Tuesday for ANZ254>256.

&&

$$
SYNOPSIS...BW/GAF
NEAR TERM...Belk/BW
SHORT TERM...BW
LONG TERM...GAF
AVIATION...Belk/BW/GAF
MARINE...BW/GAF
CLIMATE...Staff
      

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