Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
324 AM EDT Sat May 13 2023

Valid 12Z Sat May 13 2023 - 12Z Mon May 15 2023

...Heavy rain, flash flooding and severe weather likely from the Great
Plains to the Midwest...

...Much above average to record heat building across the Pacific
Northwest, while below average temperatures expected across large portions
of the Plains...

Pulses of shortwave energy will continue to stir up enough moisture and
instability to cause heavy rainfall, flash flooding and severe weather
across parts of the Great Plains and Midwest today. A Moderate Risk of
Excessive Rainfall leading to Flash Flooding is in place over south Texas
and the western Gulf Coast for today, where between 3-5"+ rainfall totals
and hourly rainfall rates greater than 1-2" are expected to be associated
with a MCS moving through the Coastal Plain early this morning. This means
that there will likely be scattered to numerous instances of flash
flooding. A broader Slight Risk area encompasses much of central/eastern
Texas as well as southern Oklahoma. The Storm Prediction Center issued a
Slight Risk of Severe Thunderstorms for portions of the Texas Coastal
Plain as the aforementioned complex likely produces wind damage and
isolated large hail. The flash flooding and severe threat will rapidly
diminish later this morning as much of the instability moves offshore.
Elsewhere, Slight Risks of Excessive Rainfall leading to Flash Flooding as
well as Severe Thunderstorms are in effect for parts of the southern
Minnesota into western Illinois thanks to the presence of a stationary
front and a sufficient thermodynamic environment to support discreet
supercells capable of producing a few tornadoes, wind damage and large
hail. Rainfall totals of 1-2" are also expected over parts of southern
Minnesota and Iowa.

While the convective threat subsides by Sunday, heavy rainfall and flash
flooding concerns do not over portions of the Central/Southern Plains.
Slight Risks of Excessive Rainfall leading to Flash Flooding are in effect
for portions of southeastern Colorado into the Texas/Oklahoma panhandle as
well as another area over south Texas. Although rainfall totals will be
less than previous days in south Texas, Sunday's threat remains due to
high soil moisture and stream levels from recent soaking rains. Any rain
that occurs in this area will likely runoff. A slow moving complex of
showers and thunderstorms will spread across the Colorado-Oklahoma-Texas
region on Sunday morning beneath an area of retrograding upper-level
energy.

A closed low over the Northern Plains will open and phase with a
descending upper-level trough from Canada. This will send a strong cold
front down through the Northeast, Ohio/Tennessee Valleys and Mid-Atlantic
regions late this weekend. Scattered showers and thunderstorms will
develop along this boundary with some potentially turning severe in the
Midwest and Tennessee Valley. Cooler temperatures will follow on the
backside of the cold front with temperature departures of 10-20 degrees
below average possible on Sunday and Monday. More anomalously cool
temperatures will be felt across the Great Plains with some 15-25 degree
below normal anomalies likely in the western parts of the Southern Plains.
Elsewhere, very warm temperatures will expand across the West.
Temperatures in the Pacific Northwest will experience highs in the 80s and
90s, which will represent 20-30+ degree anomalies. Many parts of the
coastal Pacific Northwest will tie or break temperature records this
weekend. This warmth will spread into the Rockies and Plains by early next
week.

Kebede


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