FOUS30 KWBC 091558
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1158 AM EDT Sat May 9 2026

Day 1
Valid 16Z Sat May 09 2026 - 12Z Sun May 10 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
SOUTHERN LOUISIANA AND SOUTHERN MISSISSIPPI...

A complex of storms continues this morning along and south of a
quasi-stationary frontal boundary through the FLorida Panhandle,
coastal Alabama and Mississippi, and southwest into southeastern
Louisiana. While current radar observations and hi-res guidance
trends show that much of this line has and will continue to move
offshore into the Gulf, guidance suggests forward
propagation/potential additional development is likely eastward
along the boundary through the Florida Panhandle and north Florida.
Hi-res guidance shows rain rates as high as 2"+ per hour and MRMS
observations over the last few hours support this with the
available deep Gulf moisture south of the boundary. An easterly
component to storm movement along the east-west oriented boundary
may lead to some more prolonged periods of heavy downpours as well.
However, the overall progressive nature of the system as well as
locally high FFGs should keep impacts isolated.

Meanwhile, the latest 12Z hi-res guidance shows another round of
storms developing into the afternoon hours with daytime heating
east of a dryline through eastern Texas as an upper-level shortwave
approaches the region. Some additional storms are also possible
along the outflow/effective boundary west into southwestern
Louisiana, and a cluster of storms that has maintained strength
over the northwestern Gulf may eventually reach the area as well.
Given the noted sources of heavy rainfall potential and moderate
HREF probabilities of greater than 3" totals/low probabilities of
greater than 5" totals, the Slight Risk was extended west into
southwestern Louisiana. The flash flood risk later today is less
clear further east across southeastern Louisiana and especially
into southern Mississippi as the effective front slides south with
this morning's storms. However, given lingering rainfall for much
of the area, uncertainty with the incoming cluster of storms over
the northwestern Gulf, and at least the HRRR suggesting the
potential the additional development further west this afternoon
may maintain/progress eastward later this evening/overnight, have
left the Slight Risk as is for now.

Putnam

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 LOWER MISSISSIPPI VALLEY...

The forecast reasoning and outlook area remains largely consistent,
with a Marginal Risk area extending from north-central Texas to
southeastern Oklahoma, southern Arkansas, and northern Louisiana. 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.

Pereira

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