Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
348 AM EDT Tue Aug 22 2023

Valid 12Z Tue Aug 22 2023 - 12Z Thu Aug 24 2023

...Extremely dangerous heat will persist across a widespread region
spanning from the Midwest to Gulf Coast this week...

...Heavy rain and gusty winds associated with Tropical Storm Harold to
impact South Texas today...

...Scattered flash flooding concerns exist across parts of the Great Basin
and Southwest...

A searing August heat wave is set to continue this week underneath a
potent upper level ridge anchored over the Mid-Mississippi Valley. The
oppressive heat will impact a widespread region from the Midwest to the
Gulf Coast, including much of the Great Plains as well. High temperatures
throughout these areas are forecast to reach into the upper 90s and low
100s each day through at least Thursday. When factoring in brutal humidity
levels, maximum heat indices could approach 120 degrees. While it is not
uncommon for August to feature dangerous heat, these temperatures are
extremely anomalous and likely to break numerous daily and potentially
monthly records. In fact, highs are forecast to reach up to 20 degrees
above average throughout Iowa and neighboring states over the next few
days. Very warm overnight temperatures only dropping into the upper 70s
and low 80s will compound the impacts associated with this potentially
deadly heat wave. Heat alerts (Excessive Heat Warnings, Watches, and
Advisories) have been issued from Minneapolis to New Orleans, which
includes 22 states and roughly 100 million people. Take the heat seriously
and avoid extended time outdoors. Temperatures and heat indices will reach
levels that would pose a health risk, and be potentially deadly to anyone
without effective cooling and/or adequate hydration. Remember, heat is the
number-one-weather-related cause of death in the United States.

Newly formed Tropical Storm Harold located over the western Gulf of Mexico
is anticipated to continue its westward motion and impact South Texas
today with heavy rain and gusty winds. Rainfall amounts of 3 to 5 inches,
with isolated higher amounts up to 7 inches, through early Wednesday could
produce scattered areas of flash flooding. A Slight Risk (level 2/4) of
Excessive Rainfall has been issued for the region. Additionally, tropical
storm force winds will accompany the system as it progresses inland, as
well as rough surf along the coast. By Wednesday and Thursday, Harold and
its remnant moisture is forecast to push into northern Mexico and the
Southwest/Southern Rockies. This may lead to additional flash flooding
concerns, especially near the more flood-prone slot canyons in Utah on
Thursday.

Otherwise, scattered flash flooding remains possible across the Northern
Great Basin and Intermountain West today as anomalous moisture content and
uniform southerly flow allows for potentially training
showers/thunderstorms. Farther east, precipiation chances continue to
circumvent the strong upper high over the Midwest and progress from the
Great Lakes today to the Northeast/Central Appalachians by Wednesday and
Thursday. Some isolated thunderstorms could contain damaging wind gusts.
The West and Northeast will enjoy below average temperatures to go along
with rain chances, as highs for the most locations remain in the 70s and
low 80s

Snell


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