Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
400 PM EDT Fri Aug 11 2023

Valid 00Z Sat Aug 12 2023 - 00Z Mon Aug 14 2023

...Dangerous heat will persist across much of the South through this
weekend, with a new heat wave expected to begin developing across the
Pacific Northwest by Sunday...

...Severe thunderstorms possible this evening across the Midwest and on
Saturday for parts of the Ohio Valley and Northeast...

...Monsoonal showers are expected across the Four Corners region with
generally below to near average temperatures in the West...

...New rounds of heavy showers and thunderstorms to arrive across the
Midwest by Sunday...

Dangerous heat will continue for much of the southern U.S. through the
weekend as a west to east oriented upper-level ridge of high pressure
remains in place. Widespread heat-related advisories and warnings are in
effect from Florida west through the Gulf Coast and into the Lower
Mississippi Valley and Southern Plains, with the most excessive heat
expected over portions of Texas and the Lower Mississippi Valley. Forecast
highs Friday and Saturday will range from the mid-90s in Florida to the
low 100s in Oklahoma and the Lower Mississippi Valley with highs across
Texas reaching as high as 105 to 110F. When combined with high humidity
values, heat indices will reach as high as 110 to 120F for many locations.
Numerous record-tying/breaking highs are forecast both days, with
similarly record-level warm low temperatures in the upper 70s to low 80s
providing little relief from the heat overnight. Unfortunately, the heat
looks to continue beyond the current forecast period, with some moderation
potentially by the middle of next week.

A new heat wave is also forecast to begin building across the Pacific
Northwest by Sunday as a strong ridge of high pressure builds overhead.
This will allow for temperatures to reach well through the 90s and into
the low 100s. The hottest temperatures will be over the interior valleys
and lower elevations away from the Cascades. The heat will expand in
coverage heading into early next week and near-record to record-setting
high temperatures will be possible as this ridge of high pressure persists
over the region.

Meanwhile, for the Midwest and Great Lakes, a consolidating area of low
pressure will advance from the Upper Midwest this evening eastward through
the Great Lakes region and into southeast Canada by late Saturday. A
trailing cold front will settle down into the Ohio Valley and also move
into the Northeast by Saturday night, and a combination of the low center
and front will produce scattered to broken areas of showers and
thunderstorms and some of these storms may be severe with damaging winds.
The Storm Prediction Center has highlighted a Slight Risk of severe
weather across portions of these areas. However, in the near-term, the
greatest risk of severe weather will be for this evening across areas of
northeast Kansas and northwest Missouri where the Storm Prediction Center
has highlighted an Enhanced Risk of severe weather. Some supercell
thunderstorms here will be capable of producing damaging winds, large hail
and possibly a tornado.

Areas of showers and thunderstorms are also expected to the southwest over
portions of the central and southern High Plains as a cold front sags
southward across the region. Another storm system will bring storm chances
to areas of the northern Plains by late Saturday and then across the
Midwest on Sunday. Cooler temperatures will be noted behind this next
storm system, and temperatures will be dropping below normal across areas
of the northern High Plains by the end of the weekend.

Over the West, monsoonal moisture in the Four Corners region will lead to
daily rounds of afternoon thunderstorms with a few locally heavy downpours
possible. Some isolated concerns for flash flooding will be possible. This
will also help to keep temperatures a bit below average, with highs only
into the upper 70s for some locations. Areas of the Central/Southern
Rockies and Great Basin will be a bit closer to average, seeing highs in
the mid-80s to low 90s, and upper-90s to mid-100s for the Desert
Southwest. A lingering upper-level low will keep temperatures unseasonably
cool over portions of California, as highs are expected to be in the upper
60s to mid-70s for the coast and mostly 80s for the interior valleys
outside of the deserts.

Orrison/Putnam

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