Lexington Weather

Lexington, Massachusetts, USA

86°F
8/8/2022 7:12pm 
  • Lexington Conditions: Clear
  • Temperature: 85.8°F / 29.9°CColder 2.4°F than last hour.
  • Dew Point: 73.6°FDecreased 0.3°Fsince last hour.
  • Relative Humidity: 67%Increased 4.0% since last hour.
  • Wind: Wind from SSE SSE 3 mph, 10-min avg: 3 mph, gust: 15 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 051335
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
935 AM 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/...

935 AM Update...

Highlights...

* Oppressive Heat & Humidity this afternoon

* Isolated-scattered showers/t-storms develop this afternoon
  with localized heavy rain, but many locales will remain dry

Details...

An abundance of mid level cloudiness covered the region at mid
morning. Nonetheless...pockets of partial sunshine will develop
at times. This coupled with 850T near +18C should yield high
temperatures in the lower to middle 90s. If we see a little less
sunshine than expected temps will end up on the lower end of
those values. On the flip side of the coin...if we see a bit
more than expected a few spots may approach the upper 90s.
Regardless...Heat Indices of 95 to 100 degrees are expected
this afternoon and the Heat Advisories will continue for the 
region. Some areas across parts of RI/SE MA may see Heat Indices
exceed 100 degrees given very high dewpoints into the 73 to 77 
degree range!

The other concern revolves around the development of isolated to
scattered showers & thunderstorms this afternoon, but many
locations will remain dry. We do expect to see some activity 
develop, but the areal coverage remains somewhat uncertain given
the lack of synoptic scale forcing. That being said there is a 
subtle shortwave moving across the region and expect to see 1500
to 2000 J/KG of Cape develop. This should lead to isolated to 
scattered showers and t-storms this afternoon. Tough to pinpoint
the areas with the best shot...but perhaps along a developing 
sea breeze front across eastern MA/RI this afternoon given weak
pressure gradient. Also, some terrain/mesoscale interactions 
will be another area to watch. Overall severe weather threat 
should be quite given very weak wind fields, but locally heavy 
rainfall is certainly possible given Pwats around 2 inches. But 
again many locations will remain dry; given the overall limited 
synoptic scale forcing.

&&

.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 /13Z FRIDAY THROUGH TUESDAY/...
Forecaster Confidence Levels:

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

Today...Moderate confidence.

Areas of LIFR to start the day towards SE MA. Local sea breezes 
expected to kick in for BOS around 15-17z time frame. Generally 
VFR elsewhere. Greater risk for showers and thunderstorms, 
especially across the western two-thirds of southern New 
England, which could lead to brief MVFR conditions.

Tonight...Moderate confidence. 

Mainly VFR. MVFR/IFR CIGS possible for some, mainly along the
south coast, Cape, and islands. TSRA come to an end after 
sundown, but SHRA are possible through much of the night.

Saturday...Moderate confidence.

Mainly VFR, with local MVFR in scattered SHRA and TSRA.

KBOS...Moderate confidence in TAF, mainly due to timing of any
SHRA or TSRA impacting the terminal. Timing of seabreeze
development may be off by an hour or so.  

KBDL...High 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...Belk/RM
MARINE...Belk/RM
CLIMATE...Staff
      

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