Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
418 PM EDT Thu Aug 18 2022

Valid 00Z Fri Aug 19 2022 - 00Z Sun Aug 21 2022

...Significant heavy rainfall event may lead to major flash flood impacts
in the Southwest...

...Hot weather persists for California and the Pacific Northwest with
numerous heat-related advisories in place...

...Shower and thunderstorm chances continue for the Southeast to Southern
Plains and from the Northern Plains into the Midwest into the weekend...

A significant heavy rainfall event is forecast for the Southwest as a
mid-level low and anomalously high moisture associated with a remnant
tropical wave help to enhance storm development associated with an already
active Monsoon. There is a Moderate Risk of Excessive Rainfall Friday and
Saturday for portions of southeastern Arizona and southwestern New Mexico.
Areal average rainfall totals of 2-3 inches, with locally higher amounts
approaching 5-6 inches, may lead to numerous instances of flash flooding.
Slight Risks for Excessive Rainfall are also in place for a broader area
into the Four Corners region Friday and the Southern High Plains Saturday
as additional scattered instances of flash flooding are possible. Areas of
complex terrain, slot canyons, arroyos, and burn scars are at an increased
risk for flash flooding.

Meanwhile, to the west, hot weather will persist from California northward
into the Pacific Northwest under the influence of an upper-level ridge.
Numerous heat-related advisories are in place as temperatures are forecast
to reach into the upper 90s to low 100s Friday for portions of the
interior Pacific Northwest and northern Great Basin. As an upper-level
trough approaches from the west, temperatures will cool a bit Saturday
with highs in the low to mid-90s. Further south in the central valleys of
California, the heat will remain more intense through Saturday with low to
mid-100s expected.

Widespread showers and thunderstorms will continue along a wavy,
stationary front stretching from the Southeast into the Southern Plains
and also with a frontal system moving from the Northern Plains into the
Midwest into the weekend. The greatest chance for some scattered instances
of flash flooding will be for coastal South Carolina Friday. Otherwise,
only isolated impacts are expected. 

Elsewhere, well below normal high temperatures in the 70s to low 80s are
forecast for most of the Southwest, Great Basin, and Southern Rockies due
to the widespread clouds and rain. Below normal highs are also forecast
Friday for the Southeast (low to mid-80s) and for the Northern Plains (low
to mid-70s), with temperatures increasing a few degrees closer to normal
Saturday. Hotter temperatures in the upper 80s will return to the
Mid-Atlantic and New England with otherwise tranquil conditions expected.

Putnam


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