Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
130 PM EDT Thu Jul 20 2023

Valid 00Z Fri Jul 21 2023 - 00Z Sun Jul 23 2023

...The highest risk of flash flooding/severe storms should persist into
Thursday night in and near the Colorado/Kansas Border...

...Lengthy & dangerous heat wave to continue across the Southern Tier & in
the West...

...Cooler and more comfortable air-mass to engulf the Great Plains and
Midwest...

A strong cold front pressing south and east through the Nation's Heartland
will collide with an exceptionally hot and muggy air-mass to produce
widespread thunderstorms into Thursday night. The region most at-risk for
flash flooding (Moderate Risk) and severe storms (Enhanced Risk) is the
central High Plains.  Robust thunderstorm activity could produce any
combination of flash flooding, damaging winds, large hail, and tornadoes
there. The severe weather and flash flood threat (Slight Risk) is also
present for many locations farther east, which would extend into the
evening hours on Thursday.  See the latest WPC and SPC outlooks for more
details.  By Friday the cold front continues to advance farther south and
east, placing the best threat for flash flooding and strong-to-severe
storms over the southern High Plains, Mid-South. and Northeast. By
Saturday morning, much of the Mid-South and Northeast will trend drier as
the cold front exits off the East Coast. However, the front becomes
stationary over the Gulf Coast states, setting up a stormy Saturday in the
South.

For the remainder of the work-week, much of the southern tier (south of
the advancing front) and western third of the U.S. will remain mired in
this prolonged and dangerous heat wave. Record breaking daytime highs and
warm morning lows will be common from the Desert Southwest and South Texas
all the way east to Florida. The forecast calls for daytime highs to soar
into the triple digits in the Desert Southwest and Southern Plains, while
the Gulf Coast and Mid-South can expect daytime highs in the upper 90s
that coincide with oppressively high dew points through Friday, resulting
in sweltering heat indices as high as 120 degrees in some spots.
Meanwhile, daily low temperatures remain quite warm with breaking record
warm daily minimums expected, which will limit relief from the heat
overnight. Florida will also contend with stifling heat ahead of the
front, where lighter than average winds have led to above average sea
surface temperatures due to a weaker than average Bermuda High.  Please
visit heat.gov, as well as the Key Messages issued by the Weather
Prediction Center and Climate Prediction Center for more information on
impacts from the heat wave.

Behind the cold front, cooler and drier air sweeps in. By Friday, parts of
the Central Plains could see daytime highs that are as low as 15-20
degrees below normal. The East will see milder air arrive by Saturday,
including in the Mid-Atlantic and Northeast where daytime highs look to be
several degrees below normal and humidity levels that are more refreshing
for mid-late July.

Roth/Mullinax


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