FOUS30 KWBC 100054
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
854 PM EDT Sat May 9 2026

Day 1
Valid 01Z Sun May 10 2026 - 12Z Sun May 10 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
SOUTHEAST TEXAS AND SOUTHWEST LOUISIANA...

...0100Z Update...

Based largely on the latest observational and HRRR/RAP guidance
trends, have removed the Slight Risk area across southern LA-MS,
while also removing a large chunk of the Marginal. So much of the
outlook area had been worked over by widespread convection over the
past several hours, evidenced by the sub-500 J/Kg MUCAPE values,
negative multi-hour MUCAPE trends, and increased CIN/strengthening
low-level capping inversion below 950 mb per 00Z soundings.

Meanwhile, the upper level jet streak and favorable right-entrance
region will lift E-NE and away from the region, which in concert
with the H5 shortwave flattening and shifting east of the area as
well, will diminish any dynamical forcing necessary to spur new
convection overnight. As a result expect the lingering isolated/
localized excessive rainfall threat to diminish after midnight CDT.

Hurley


Day 2
Valid 12Z Sun May 10 2026 - 12Z Mon May 11 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE SOUTHERN PLAINS AND THE ARKLATEX...

...2030Z Update...

Prior synoptic overview of the forecast remains on track. The
inherited Marginal was adjusted based on the now-avaible hi-res
guidance with a general southwesterly shift to focus on expected
convection ahead of the cold front and east of a dryline. Storms
may be ongoing at the start of the period further north over
Oklahoma and could maintain into Arkansas and even northern
Louisiana. Given uncertainty on the extent and duration of these
storms and early morning lull in instability, there is no extension
of the outlook based on their potential. However, they may
ultimately impact the northern extent of new development across
Texas later tomorrow afternoon and evening. There could also be the
need for a targeted Slight Risk where convective coverage looks to
maximize immediately ahead of the cold front with initial cell
clustering/merging and upscale growth, currently progged along and
south of the I-20 corridor across north-central into central Texas.
Some of the hi-res guidance suggests locally heavy totals of 3-4"
could be possible. However, given the overall progressive nature of
the front, high FFGs, and uncertainty with respect to where this
corridor may ultimately set up (with potential overnight/early day
convection influence), a Marginal Risk remains sufficient for now.

Putnam

...Previous Discussion...

The forecast reasoning and outlook area remains largely consistent,
with a Marginal Risk area extending from north/central Texas into
the ArkLaTex. A cold front dropping south through the Plains will
become a primary focus for deepening moisture (PWs increasing to
around 1.5 inches) and storm development.

Synoptic support will strengthen as shortwave energy moves into the
base of a broader-scale trough, placing the region within an area
of strong ascent, supported by coupled upper-jet forcing. This
combination of moisture and favorable dynamics, along with
increasing instability, will promote broadening storm coverage by
the afternoon. While storms will eventually gain a more steady
southward progression, initial storm organization may be
characterized by slow movement and mergers. These factors combined
with the potential for high rainfall rates, support the
maintenance of the Marginal Risk for localized flash flooding.

Pereira

Day 3
Valid 12Z Mon May 11 2026 - 12Z Tue May 12 2026

The probability of rainfall exceeding flash flood guidance is less
than five percent.

Putnam

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