Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
358 PM EDT Wed Aug 19 2026

Valid 00Z Thu Aug 20 2026 - 00Z Sat Aug 22 2026

...Heavy rain and flash flooding threats across the Midwest, Ohio Valley
and southern Arizona today, shifting east to the Mid-Atlantic coast on
Thursday...

...Severe storms possible across mid-Mississippi Valley today through
tonight...

... Severe storms possible across Nebraska and flash flooding possible in
the Southeast on Friday...

...Dangerous heat persists in the South while building into the
Southwest...

Heavy rain and thunderstorms have developed across much of eastern
Nebraska moving into  southern portions of Iowa and northern portions of
Missouri due to a cold front moving through the central plains. SPC has a
slight risk for severe weather where these storms are capable of producing
 severe wind gusts and hail as daytime heating maximize. WPC has a slight
risk of excessive rainfall also in the general area. Clusters of organized
heavy showers and thunderstorms will continue traveling eastward across
the central Plains toward the mid-Mississippi Valley this evening through
tonight. These thunderstorms are forecast to become more focused in the
mid-Mississippi Valley through tonight ahead of a low pressure wave
traveling eastward. SPC has a slight risk of severe thunderstorms across
the mid-Mississippi Valley and WPC has a slight risk of excessive rainfall
extending farther north into the Midwest and Ohio Valley.

Meanwhile, monsoonal showers and thunderstorms will be most active during
the late-day hours across the Four Corners states, where the WPC has
highlighted a marginal risk of Excessive Rainfall through the next couple
of days. In addition, a slight risk is in place across southern Arizona
for today.

By Thursday, the cold front will advance farther eastward and begin to
merge with the meandering front to the south.  A convergence zone
sandwiched between these two fronts will focus a corridor of enhanced
rainfall.  Heavy rain with embedded thunderstorms is possible along this
corridor roughly from I-95 east to the northern Mid-Atlantic coast.  WPC
has highlighted this area for a slight risk of excessive rainfall mainly
later on Thursday when daytime heating is maximized. In addition, SPC has
highlighted a slight risk for severe weather where the main threat is
damaging wind gusts. By Thursday night into early Friday, the heavy rain
should temporarily exit the Mid-Atlantic coast as a low-pressure wave
slides off the coast of southern New England. Another round of severe
weather is possible for eastern Nebraska into Minnesota and Wisconsin
Thursday afternoon into the evening. A weak low pressure system will
migrate from Minnesota into the U.P. Michigan, creating a weak surface
front along with dew points in the low to mid 60s to generate severe
weather. SPC has outlined a slight risk of severe weather for the area
where the main threat will be large hail, and isolated wind damage.

On Friday, much of central and eastern Nebraska will yet again experience
another round of severe weather. A low pressure system will develop along
a surface trough with ample moisture and strong instability in place to
initiate some supercell thunderstorms. SPC has highlight a slight risk for
severe weather where main threat will be isolated to scattered damaging
hail (some greater than 2 inches),and some severe wind gusts for Friday
afternoon into the evening hours. As for the Southeast, scattered to
numerous thunderstorms are forecast within a very moist and unstable
environment along a surface trough. Single to multi-cell convection will
pose the risk for excessive rainfall where WPC has highlighted a slight
risk for  excessive rainfall from  northern portions of South Carolina to
the southern portions of Virginia.


Temperature-wise, the southern tier of the Lower 48 remains mired in a
steamy air-mass even by mid-to-late August standards. Record highs and
record warm minimum temperatures will be common with the Southeast at the
heart of the anomalous heat through today. The upper ridge is forecast to
strengthen over the Southwest while cool Canadian air dips further into
the Great Lakes. Some cases of record-breaking warmth are expected in the
Desert Southwest and Southern Plains as temperatures dip into the 40s near
the Canadian border in the upper Midwest. Extreme Heat Warnings are in
effect for much of the Desert Southwest, and Extreme Heat Warnings remain
in effect across portions of the southern Plains to the Deep South.  Heat
Advisories are in effect for all of Florida and the southeast U.S. coast. 
Overnight lows will be so warm (low 80s in some cases) that, when combined
with oppressive dew points, little-to-no relief from the scorching daytime
highs will be available. Residents are advised to follow proper heat
safety tips by limiting outdoor activity, staying hydrated, ensuring
access to A/C or cooling centers, and checking on vulnerable friends,
neighbors, and family members.


Green/Kong


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