104
FXUS01 KWBC 040746
PMDSPD

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
345 AM EDT Thu Jul 04 2024

Valid 12Z Thu Jul 04 2024 - 12Z Sat Jul 06 2024

...Extremely dangerous and record-breaking heatwave to impact much
of the West through this weekend...

...One more day of oppressive heat and humidity across the
Southern Plains and Lower Mississippi Valley today before steamy
temperatures focus over the Mid-Atlantic and Southeast...

...Flash flooding and severe thunderstorms possible throughout
parts of the Midwest, Ohio Valley, and Southern Plains this
Independence Day...


A significant and extremely dangerous heatwave is set to build
throughout the West to end this week and into the extended holiday
weekend, with several days of record-breaking heat forecast. An
upper-level high situated just off the West Coast today is
forecast to strengthen and reorient directly over the western U.S.
by Friday. This pattern will support well above average
temperatures over California and into southwest Oregon today
before heat spreads further throughout the western U.S. this
weekend. High temperatures are forecast to reach into the 105-115F
range for interior California away from the immediate coastline,
as well as across much of the Desert Southwest. Locally higher
temperatures into the 120s are possible in the typical hot spots
of the Desert Southwest. Searing afternoon temperatures will also
spread into the Northwest and parts of the central Great Basin,
with widespread highs rising into the 90s and low 100s. Dozens of
daily record high temperatures are possible, expressing the rarity
of this early-July heatwave. The duration of this heat is also
concerning as scorching above average temperatures are forecast to
linger into next week. Heat impacts can compound over time,
therefore it is important to remain weather aware and follow the
advice of local officials. This level of heat throughout parts of
the Mojave Desert and Sacramento/San Joaquin valleys of California
could pose a risk to anyone if proper heat safety is not followed.
It is imperative to stay hydrated, out of direct sunlight, and in
buildings with sufficient air-conditioning when possible. It is
also equally as important to check on the safety of vulnerable
friends, family, and neighbors.

Oppressive heat and humidity will also be found throughout the
southern Plains and lower Mississippi Valley today, while
expanding eastward to the Mid-Atlantic and Southeast for the end
of the week. High temperatures rising into the upper 90s and low
100s are expected, with heat indices soaring into the 110s across
the lower Mississippi Valley. Warm overnight conditions in the
upper 70s and low 80s will offer little relief, leading to a
dangerous situation for those without access to adequate cooling.
A cold front entering the southern Plains is anticipated to offer
cooler and below average temperatures to Oklahoma, much of
northern/western Texas, and the Mid-South by Friday. Above average
temperatures are then anticipated to confine to the Southeast and
Mid-Atlantic for the start of the weekend, with afternoon highs
into the mid-to-upper 90s. If planning to spend an extended amount
of time outdoors this Fourth of July, be sure to use caution and
act quickly if you see signs of heat-related illnesses.

An active and stormy weather pattern over the central U.S. is
expected to create chances for severe thunderstorms and heavy
rainfall, which could impact holiday gatherings through early this
weekend. A developing area of low pressure over the northern
Plains is forecast to progress into the upper Midwest by tonight
and team up with a lingering frontal boundary stretching from the
lower Great Lakes to the southern Plains to trigger some
meteorological fireworks. Thunderstorm chances span from the
southern Plains/Rockies to the middle/upper Mississippi Valley and
also eastward to the Ohio Valley and Mid-Atlantic. However, the
greatest threat for strong to severe thunderstorms will be
near/along the frontal boundary through parts of the middle/upper
Mississippi Valley and southern Plains. Damaging wind gusts and
frequent lightning are the most likely weather hazard associated
with these Fourth of July storms. Flash flooding will remain a
concern throughout the upper Midwest as well due to yet another
round of thunderstorms overlapping areas dealing with ongoing
river flooding and saturated soils, with scattered flash flooding
also possible between the Ohio Valley and southern Plains. On
Friday, thunderstorms will continue to progress eastward with the
frontal boundary into much of the eastern third of the country.
Isolated strong to severe storms and flash flooding are possible.
The greatest threat for damaging wind gusts associated with these
storms will be across the upper Ohio Valley. Elsewhere, daily
thunderstorm chances associated with daytime heating are possible
along the Gulf Coast and Florida. Scattered showers and
thunderstorms are also possible throughout the north-central U.S.
this weekend as upper troughing remains over the region. Residents
and visitors located within areas expecting severe weather and/or
heavy rainfall are advised to remain weather aware, have multiple
ways to receive warnings, and never drive across flooded roadways.

Have a safe Independence Day!

Snell


Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php
$$