513
FXUS01 KWBC 031928
PMDSPD

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
326 PM EDT Wed Jul 03 2024

Valid 00Z Thu Jul 04 2024 - 00Z Sat Jul 06 2024

...Dangerous heatwave to impact much of the West, while oppressive
heat and humidity also swelter areas from the Southern Plains to
the Mid-Atlantic...

...Flash flooding and severe thunderstorms possible over the next
few days across portions of the Plains, Midwest, and Ohio Valley...


Record-breaking and dangerous heat is forecast to make this Fourth
of July week a scorcher across much of the West and from the
southern Plains to the Mid-Atlantic. Nearly 150 million residents
are currently under heat-related watches, warnings, and advisories
throughout 21 states as of this afternoon. An upper-level high
situated just off the West Coast today is forecast to strengthen
and reorient directly over the western U.S. by the end of the
week. This pattern will support well above average temperatures
over California today before heat spreads further along the West
Coast by the end of the week. High temperatures are forecast to
reach into the 105-115F range throughout interior California away
from the immediate coastline, as well as into much of the Desert
Southwest. Afternoon temperatures will also begin to increase
across much of Oregon and Washington by Thursday and Friday, with
widespread highs soaring into the 90s. Dozens of record highs 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 the Sacramento and San Joaquin
valleys of California could pose a risk to anyone if proper heat
safety is not followed. This includes staying hydrated, out of
direct sunlight, and in buildings with sufficient
air-conditioning. It is also very 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 into the Independence
Day holiday while also expanding eastward to the Mid-Atlantic 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 and much of
northern/western Texas by Friday.

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 this week. A
developing area of low pressure over the central High Plains
forecast to progress into the upper Midwest by Thursday along with
a lingering frontal boundary stretching from the lower Great Lakes
to the central Plains are anticipated to be the triggers for some
meteorological fireworks. For this evening, the best chances for
scattered flash flooding due to thunderstorms capable of producing
intense rainfall rates is forecast between eastern Kansas and the
Ohio Valley along the aforementioned frontal boundary. Instances
of severe weather (mainly damaging wind gusts) are also possible,
with chances for severe storms also located in parts of the
northern/central High Plains closer to the developing low pressure
system. By Independence Day, 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 and
upper Mississippi Valley. Damaging wind gusts and frequent
lightning are the most likely weather hazard associated with these
Fourth of July storms, with isolated strong storms also possible
into the Midwest, Ohio Valley, and Mid-Atlantic by tomorrow
evening. 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. Residents and visitors located within areas
expecting severe weather and/or heavy rainfall this week are
advised to remain weather aware, have multiple ways to receive
warnings, and never drive across flooded roadways.

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 heavy rainfall will be
associated with the area of low pressure itself across parts of
the Upper Mississippi to lower Great Lakes.

Santorelli/Snell


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