Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1100 AM EDT Tue Apr 22 2025

Day 1
Valid 16Z Tue Apr 22 2025 - 12Z Wed Apr 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTH...

The inherited Marginal Risk areas across the Panhandles of Texas
and Oklahoma as well as the newly expanded Marginal from the lower
Mississippi Valley to the southern Appalachians were combined to
cover much of Texas with this update. There remain 2 distinct
features forcing the thunderstorms, a stationary boundary draped
from the Lower Mississippi Valley to the southern Appalachians, and
a progressive dry line that will spawn new thunderstorms across
western and central Texas later this afternoon though tonight.
While the area in between...namely east Texas, has a notably lower
chance of flash flooding, enough of the guidance suggests there to
be enough overlap late tonight between earlier convection and those
areas harder hit over the past day or so to justify the combining
of the inherited Marginal Risk areas.

This summer-like pattern of convection is much less predictable
than the colder season larger precipitation shields of the past
several months. It's therefore becoming the season where larger
swaths of the country are broadly under a localized threat for
flash flooding as thunderstorm complexes interact with one another
in largely unpredictable ways, with enhanced impacts should those
interactions occur over urban areas. The combined Marginals thus
highlight these larger features for the potential for training
convection once cell interactions are taken into account. Given the
increasing amounts of atmospheric Gulf moisture advecting into
these features, resultant convection will have the potential to
cause localized rainfall rates of up to 2 inches per hour.
Localized flash flooding is most likely to occur where these rates
coincide with lower FFGs from recent heavy rainfall.

Wegman


Day 2
Valid 12Z Wed Apr 23 2025 - 12Z Thu Apr 24 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN PLAINS...

Several shortwaves will be exiting the Rockies throughout the day
with several pockets of convective development sprawled across the
Central and Southern High Plains by the evening hours. While the
confidence continues to be lower on the maximum amounts there is
however higher confidence on the potential for scattered flash
flood prospects. Although the location of QPF maxima vary, there
is a general consensus of a widespread 1 to 2 inches from the Front
Range of Colorado/Wyoming/Nebraska south to the Red River Basin
near Texas to Kansas/Oklahoma. Some of these areas will have seen
significant rainfall prior to any additional impacts leading to
some localized lower FFG indices once the event occurs. The
inherited Marginal continued to mostly highlight areas across the
Plains that had an elevated threat for heavy rainfall and flash
flooding. The latest guidance and WPC QPF trended higher with QPF
over northeast Kansas, southern Nebraska, southwest Iowa and
northwest Missouri. As such, the Marginal Risk area was modified to
encompass that part of the region.

Campbell/Kleebauer


Day 3
Valid 12Z Thu Apr 24 2025 - 12Z Fri Apr 25 2025

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
KANSAS, OKLAHOMA, ARKANSAS AND MISSOURI...

The pattern will be favorable for multiple rounds of showers and
thunderstorms to move through the south-central U.S. With a moist,
unstable flow expected and shortwave energy passing through heavy
rainfall will likely develop across the region which may lead to
local flash flooding. Areal averages of 1 to 2 inches are forecast
with locally higher amounts possible. A Slight Risk for excessive
rainfall is in effect for a large portion of Kansas, northern
Oklahoma, far northwest Arkansas and western Missouri. A Marginal
Risk area spans from northern Texas to southern Nebraska and
extreme southwest Iowa.

Campbell

Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt