Lexington Weather
Lexington, Massachusetts, USA
- Few Clouds
-
78.3°F / 25.7°C
-
72.3°F
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82%
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SE 5 mph, 10-min avg: 3 mph, gust: 11 mph
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- 10 miles
- 0.00 in
National Weather Service Forecast for:
Lexington MA
Issued by:
National Weather Service Norton, MA
Today through Friday
Point Forecast Updated 5:17 am EDT Aug 3, 2020
Today:
Mostly Sunny
Hi 91 °F
Mostly sunny, with a high near 91. Southwest wind 10 to 14 mph.
Tonight:
Mostly Clear then Slight Chance Showers
Lo 72 °F
A slight chance of showers after 1am. Partly cloudy, with a low around 72. Southwest wind 3 to 8 mph. Chance of precipitation is 20%.
Tuesday:
Chance Showers and Patchy Fog
Hi 84 °F
A chance of showers, with thunderstorms also possible after 4pm. Patchy fog before 10am. Otherwise, cloudy, with a high near 84. South wind 3 to 8 mph. Chance of precipitation is 50%. New rainfall amounts between a quarter and half of an inch possible.
Tuesday Night:
T-storms and Windy
Lo 71 °F
Showers and possibly a thunderstorm. Low around 71. Windy, with a south wind 14 to 19 mph increasing to 25 to 30 mph in the evening. Winds could gust as high as 41 mph. Chance of precipitation is 80%. New rainfall amounts between three quarters and one inch possible.
Wednesday:
Showers Likely
Hi 86 °F
Showers likely and possibly a thunderstorm before 8am, then a chance of showers and thunderstorms, mainly between 8am and 4pm. Partly sunny, with a high near 86. Southwest wind 9 to 14 mph. Chance of precipitation is 60%.
Wednesday Night:
Partly Cloudy
Lo 65 °F
Partly cloudy, with a low around 65. West wind 3 to 6 mph.
Thursday:
Sunny
Hi 84 °F
Sunny, with a high near 84. West wind 3 to 5 mph.
Thursday Night:
Mostly Clear
Lo 64 °F
Mostly clear, with a low around 64. West wind around 5 mph becoming calm in the evening.
Friday:
Mostly Sunny
Hi 84 °F
Mostly sunny, with a high near 84. Calm wind.
FORECAST DISCUSSION
Area Forecast Discussion
for Lexington MA
000
FXUS61 KBOX 031104
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
704 AM EDT Mon Aug 3 2020
.SYNOPSIS...
Dry, quiet and warm across southern New England today. Showers
and a few thunderstorms developing Monday night into early
Tuesday from southwest to northeast ahead of Isaias. Isaias is
expected to impact southern New England Tuesday night with heavy
rain in western areas and gusty winds in eastern areas. Heading
into late week, temperatures remain warm, but more comfortable
with lowering dewpoints.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
7 am update...
No significant changes with this morning's forecast update.
Seeing a mix of clouds and sun out there, and the clouds will
continue to decrease through the day.
Previous Discussion...
Today...
Cold front stalls over eastern portions southern New England
and high pressure briefly builds into the region. Flow at 925
and 850 hPa will become westerly in wake of the front. This will
result in strong mixing and downsloping, which will dry dew
points and bring warm temperatures. Expect dew points to fall
into the lower to mid 60s. Bumped highs to the 90th percentile
of guidance. This results in temperatures in the 80s across the
higher elevations and immediate south coast, but will see lower
90 degree readings elsewhere.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Monday night through Tuesday morning...
Moisture advecting into southern New England ahead of Isaias as
the mid level ridge axis builds into the Gulf of Maine. This
will shift flow from southwest to south southwest. Will see
PWATS increase to roughly 1.5 to 2 in depending on the forecast
guidance. This will also be roughly in the RRQ of a 250 hPa 95+
kt jet and the stalled out front over the region. This will
bring showers and perhaps a few thunderstorms. Best shot for
thunderstorms is along the south coast of RI/CT. The
thunderstorm risk spreads northward into northern CT, RI,
central and eastern MA Tuesday morning. Some of these
showers/storm could be heavy at times given the tropical airmass
advecting in.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Highlights...
* Tropical Storm Isaias will move into the New England region around
Tuesday night into early Wednesday bringing rain and gusty winds.
Minor coastal flooding is possible along with increased rip
current risk and high surf.
* The biggest rain threat will be in western MA/CT or even west of
New England, in eastern NY. Main threat would be urban flooding.
Strong winds are possible with gusts 45-55 mph and localized gusts
up to 60 mph. Axis of heavy rain and winds will be contingent on
the eventual track of the system.
* High pressure and dry weather move in for the latter half of the
week into the weekend with seasonable temperatures.
Details...
Tropical Storm Isaias is currently spinning off the coast of
Florida, but should be arriving in/near southern New England around
Tuesday afternoon/Tuesday night. 00Z ECMWF guidance has come in with
a track further west and in agreement with the GFS/NAM solution
taking the low center up the MA/NY border. Should this outcome
materialize, the change in impacts would be 1) a further shift west
in the heaviest rainfall/urban flooding risk - into eastern NY but
potentially as far east as the Berkshires 2) potential for those 45-
60 mph wind gusts over most all of southern New England.
Fortunately, the storm will be accelerating and weakening as it
moves up the east coast so it won't be a long duration event.
However, as it undergoes a transition to an extratropical system the
wind fields will be expanding. Another concern during the evening
into overnight Tuesday will be the potential for isolated tornadoes.
Timing of course would change if the storm's arrival time changes.
Several hundred J/kg CAPE will provide plenty of instability
together with a ton of 0-6 km effective shear for sustained
updrafts. Add on top of it some serious low level spinning (0-1 km
shear of 50 kts and 0-1 km SRH over 500[!] m2s2) and we'll have to
keep an eye on any storms that get going. The storm lifts out and a
dry slot moves in bringing a quick end to the rain on Wednesday,
though the rough seas will linger into Thursday. The latter half of
the week is much drier as high pressure moves in under rising mid
level heights. Highs remain in the 80s through the weekend.
Impacts of Isaias...
Of course the magnitude of any impacts at this point remains+
uncertain, depending on the eventual track and strength over
southern New England. At this point the main concern for potential
heavy rain in MA/CT (2-4", locally 6") is over the the Berkshires.
Whether the axis of heaviest rainfall sets up here or further west
into NY will determine if we deal with any urban flooding issues.
Winds gusting 45-55 mph with localized gusts to 60 mph are possible
which, given the leaves on our trees (compared to, say, a Noreaster
in January) could cause some serious power outage issues from downed
trees and wires. A much less likely but real threat is damage from
tornadoes, especially late Tuesday into Tuesday night based on
current timing. At this point, expecting that any coastal flooding
would be minor, along the south coast. High surf and rip current
risk will be elevated Tuesday and Wednesday. Wednesday may see the
highest impact when it comes to rip current risk given that it would
be the better beach day, post Isaias.
&&
.AVIATION /11Z MONDAY THROUGH FRIDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
12 Z update...
Today...High confidence
VFR with WSW to W winds. Winds become gusty during the
afternoon.
Monday night...Moderate confidence
VFR initially with scattered showers and isolated t-storms
mainly in western MA & northern CT late. Areas of fog possible
late near the south coast.
Tuesday...Moderate confidence
Conditions deteriorating with increasing winds and wind gusts.
Will be dependent on how quickly showers/storms move into the
region due to Isaias.
KBOS Terminal...Moderate confidence in TAF. Scattered tstms this
evening.
KBDL Terminal...Moderate confidence in TAF. Low risk for tstms,
possibly strong through 03Z.
Outlook /Tuesday Night through Friday/...
Tuesday Night: MVFR/IFR conditions possible. Strong winds with
gusts up to 50 kt. SHRA, TSRA likely.
Wednesday: VFR. Breezy. Chance SHRA, slight chance TSRA.
Wednesday Night through Friday: VFR.
&&
.MARINE...
Small Craft Advisories continue into Monday due to gusty winds
and seas building to 5 ft mainly over the southeastern waters.
Seas building in association with Isaias Tuesday into
Wednesday.
Outlook /Tuesday Night through Friday/...
Tuesday Night: Low risk for gale force winds with gusts up to
45 kt. Rough seas up to 11 ft. Chance of rain showers, slight
chance of thunderstorms.
Wednesday: Low risk for Small Craft Advisory winds with gusts
up to 30 kt. Areas of rough seas. Slight chance of rain
showers, isolated thunderstorms.
Wednesday Night: Winds less than 25 kt. Seas up to 5 ft.
Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Thursday Night through Friday: Winds less than 25 kt.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Tropical Storm Watch for CTZ002>004.
MA...Tropical Storm Watch for MAZ002>024-026.
RI...Tropical Storm Watch for RIZ001>008.
MARINE...Tropical Storm Watch for ANZ230>237-250-251-254>256-270>273.
&&
$$
SYNOPSIS...BL/BW
NEAR TERM...BL/BW
SHORT TERM...BL/BW
LONG TERM...BW
AVIATION...BL/BW
MARINE...BL/BW/JWD
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