Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
344 PM EDT Fri Jul 15 2022

Valid 00Z Sat Jul 16 2022 - 00Z Mon Jul 18 2022

...Dangerous heat to continue across much of the Central and Western
United States...

...Heavy rain and possible flash flooding for portions of the
Intermountain West, Rockies, and Gulf Coast region through tonight, with
severe weather possible across the northern High Plains...

...Instances of flash flooding possible throughout the Ohio Valley on
Sunday...


In typical mid-July fashion, many parts of the country are forecast to
continue contending with heat and thunderstorms over the next several
days. A strong and stagnant upper-level ridge stretching from the
Southwest to the southern High Plains will be the driver for above normal
temperatures throughout the West and central United States. Highs into the
mid-to-upper 90s and triple digits will be widespread over the Great
Plains and into parts of the middle/lower Mississippi Valley this weekend.
These hot daytime temperatures combined with warm overnight lows around 80
degrees could make conditions particularly dangerous for any residents
without access to working air conditioning. Simmering temperatures near
the century mark are forecast to persist over northern Plains and
Intermountain West through the weekend as well, with even hotter weather
found in the Desert Southwest. Arizona, southern Nevada, and
central/southern California will see highs soar into the 100s and 110s.
Elsewhere, below average temperatures are expected across the Pacific
Northwest, while warm and near average temperatures mostly in the 80s
remain over the Great Lakes and East Coast.

Monsoon season kicked off fairly early this year over the Southwest and
for some locations it is expected to peak this afternoon and evening
throughout the Colorado River Basin. While much of this region is
desperate for rainfall, too much rain in a short period of time could be
dangerous. Near record precipitable water amounts streaming from southern
Nevada to southern Wyoming will allow for any developing thunderstorms to
contain intense rainfall rates. For susceptible terrain, such as burn
scars and slot canyons, heavy rainfall could lead to rapid runoff and
flash flooding. A Slight Risk (level 2/4) of excessive rainfall has been
issued for a broad region that extends from northern Arizona and eastern
Nevada to southern Wyoming. Flash Flood Watches have also been issued. By
this weekend, thunderstorm chances are expected to continue but become
more scattered in nature, leading to additional isolated chances for flash
flooding. Farther north, a shortwave trough swinging across the northern
Rockies this afternoon may spark thunderstorms capable of containing
damaging wind gusts and large hail throughout the northern High Plains.

Shifting to the eastern U.S., a sultry airmass draped across the Southeast
and Gulf Coast is anticipated to continue producing scattered and
unorganized thunderstorm activity through at least the beginning of the
weekend. A few storms could produce torrential downpours and remain
stationary long enough to produce isolated flash floods. Low-lying areas
and urban regions are most at risk for impacts associated with flooding. A
Slight Risk of Excessive rainfall is in effect through early Saturday,
with the risk areas drastically diminishing for the weekend.

Additionally, thunderstorm complexes forming near a slowly lifting warm
front extending from the Mid-Mississippi Valley to the Mid-Atlantic this
weekend may produce the threat of flash flooding over the Ohio Valley. The
latest precipitation forecast depicts widespread 1-3 inches of total
rainfall possible, with locally higher amounts likely. The Excessive
Rainfall Outlook was upgraded this afternoon to include a Slight Risk from
western Pennsylvania to far northeast Arkansas on Sunday, where
probabilities are greatest for scattered flash floods to occur.

Snell


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