Lexington Weather

Lexington, Massachusetts, USA

89°F
8/8/2022 5:57pm 
  • Lexington Conditions: Partly cloudy
  • Temperature: 88.9°F / 31.6°CColder 3.4°F than last hour.
  • Dew Point: 74.1°FDecreased 0.7°Fsince last hour.
  • Relative Humidity: 62%Increased 5.0% since last hour.
  • Wind: Wind from WSW WSW 2 mph, 10-min avg: 4 mph, gust: 16 mph
  • Barometer: 29.79 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 051811
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
211 PM EDT Fri Aug 5 2022

.SYNOPSIS...

Heat and humidity will be the main weather story right into 
early next week. This hot stretch continues today, with even 
higher humidity. The greatest potential for showers and
thunderstorms will be today into Saturday, with localized heavy
rainfall possible at times. It may be Tuesday, or later, before
this heat and oppressive humidity finally breaks in a
significant way.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...

205 PM Update...

* Isolated to scattered thunderstorms with locally heavy
  developing this afternoon, but many locations will remain dry

Oppressive heat & humidity were in place across the region at
mid-afternoon. Current temps were mainly in the upper 80s to the
lower 90s and with high dewpoints in place current heat Indices
were well up into the 90s to near 100. Temps and heat indices
will likely climb a few more degrees by late afternoon and Heat
Advisories continue for the region.

In addition...isolated thunderstorms were beginning to develop 
at mid-afternoon. Capes were on the order of 1500 to 2000 J/KG 
and there was a subtle shortwave embedded in the flow. Tough to 
pinpoint the areas with the best shot of activity given the 
limited upper level forcing. However, an area along a developing
sea breeze front across eastern MA/RI might be one area to 
watch. Also some terrain/mesoscale interactions will be another 
area to watch. Overall severe weather threat should be quite 
limited given very weak wind fields, but locally heavy rainfall 
is certainly possible given Pwats around 2 inches and slow 
movement of any storms. This activity will be hit or miss and 
many locations will remain dry.

&&

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

With the weak wind fields in place, expecting thunderstorms to
diminish quickly after sunset. The same cannot be said for the
possibility of showers tonight. Showers and thunderstorms
redevelop for Saturday. Have little confidence in trying to time
out the risk for specific locations given the rather soupy
environment. Have greater concern for downpours than severe
weather yet again Saturday.

Above normal temperatures and near oppressive humidity
continues. Will likely need to extend Heat Advisories for some
areas Saturday. These areas could change daily, so will take
any extensions on a daily basis.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...

Highlights

* Oppressive heat and humidity continues through Monday.
  Additional heat headlines likely for Sunday, and possibly 
  Monday.

* Slow-moving frontal boundary early next week may support a
  period of unsettled weather

* Temperatures moderate closer to normal mid-week.

Sunday and Monday

Little change in the weather pattern for Sunday and Monday as 
deep southwest flow continues to pump warm moist air into 
southern New England. Dewpoints remain in the low 70s while 
afternoon temperature stop out in the low to mid 90s. This will 
translate to heat indices in the mid to upper 90s for both 
Sunday and Monday. Thus, additional heat headlines are likely 
for some areas on these days. Most areas are expected to stay 
dry during this time frame, but with the unstable atmosphere, we
can't rule out a brief spot shower or thunderstorm during the 
afternoon.

Next Week

Quite a bit of uncertainty beyond Monday as global models are 
struggling to come to a consensus on how to resolve a slow 
moving cold frontal boundary early next week. GFS supports an 
earlier arrival Monday night, while the EURO supports a later 
arrival on Tuesday. Have leaned on NBM on guidance due to the 
uncertainty. The expectation is that this frontal boundary will 
support periods of wet/unsettled weather in the Tuesday to 
Thursday time frame. Additionally as an upper-level trough 
associated with this boundary digs into the Northeast, we should
see temperatures return to something closer to normal. While 
the models are in quite a disagreement early in the week, there 
is better agreement later in the weak for coastal low developing
off the east coast. Perhaps this will introduce an opportunity 
for so much needed rainfall! Check back for more details in the 
coming days.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...

Forecaster Confidence Levels:

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

18z TAF Update...

This afternoon into tonight...Moderate Confidence.

VFR conditions persist outside the isolated to scattered 
thunderstorms that will develop into early this evening. This
activity should diminish with the loss of daytime heating. 
Otherwise...the main concern will be for areas of fog 
developing later tonight which may be locally dense in the
typically prone spots. The threat for widespread low clouds 
though will probably be confined to areas near the south coast 
with the best shot at Nantucket. Winds becoming Light/Calm 
tonight except more from the SW at 5-10 knots across the Cape 
and Islands.

Saturday...High Confidence.

Mainly VFR once the areas of fog burnoff shortly after sunrise.
However, isolated to widely scattered showers/t-storms will be
possible in the afternoon with the greatest risk in northern MA
and interior southern New England. S-SW winds 10 to 15 knots,
but there may be a couple hour window for sea breezes across the
eastern and especially northeast MA coast. Any sea breezes
should be overcome as the day wears along.

Saturday night...High Confidence. 

Mainly VFR and think the main threat for low clouds/fog will be
confined to areas near the south coast, Cape and Islands. Winds
will be from the WSW 5-10 knots. 

KBOS...Moderate Confidence in TAF. 

KBDL...Moderate Confidence in TAF.

Outlook /Saturday Night through Tuesday/...

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

Monday: Mainly VFR, with areas MVFR possible. Breezy. Chance
SHRA.

Monday Night: Mainly MVFR, with areas VFR possible. Breezy.
Chance SHRA, isolated TSRA.

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

&&

.MARINE...

Forecaster Confidence Levels:

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

High confidence. 

Areas of fog should dissipate this morning. Winds and seas to 
remain relatively tranquil through Saturday.

Outlook /Saturday Night through Tuesday/... 

Saturday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Slight chance of rain showers. 

Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Slight chance of rain showers. 

Sunday Night: Low risk for Small Craft Advisory winds with
gusts up to 20 kt. Seas up to 5 ft. Slight chance of rain
showers. 

Monday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Slight chance of rain showers. 

Monday Night: Winds less than 25 kt. Seas up to 5 ft. Chance of
rain showers, isolated thunderstorms. 

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

&&

.CLIMATE...
August 5th daily record maximum high temperatures...

BOS - 100F [1955]
ORH - 96F  [1944]
PVD - 100F [1944]
BDL - 101F [1955]

August 5th daily record maximum low temperatures...

BOS - 76F [1938]
ORH - 73F [1938]
PVD - 77F [1938]
BDL - 76F [1938]

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Heat Advisory until 8 PM EDT this evening for CTZ002>004.
MA...Heat Advisory until 8 PM EDT this evening for MAZ002>023-026.
     Air Quality Alert until 11 PM EDT this evening for MAZ007-015-
     016.
RI...Heat Advisory until 8 PM EDT this evening for RIZ001>007.
MARINE...None.

&&

$$
SYNOPSIS...Belk/RM
NEAR TERM...Frank
SHORT TERM...Belk
LONG TERM...RM
AVIATION...Frank/RM
MARINE...Belk/RM
CLIMATE...Staff
      

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