FOUS30 KWBC 072017
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
417 PM EDT Thu May 7 2026

Day 1
Valid 16Z Thu May 07 2026 - 12Z Fri May 08 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM SOUTHERNMOST
GEORGIA TO THE FLORIDA PANHANDLE...

...16Z Update...
The northern extent of the Marginal Risk was trimmed as an east-
west axis of thunderstorms enter the Florida Panhandle. Confluent
low-level flow directed into the upwind and minimally capped
segment of a slow moving cold front could support new thunderstorm
development and periodic training in the short term. However, with
time a shortwave trough approaching the Tennessee Valley will
redirect the strongest low-level forcing and moisture downstream of
the complex. As such, the HREF and REFS (while being too slow with
the convection) both suggest these storms should lessen in
coverage and intensity as they lose latitude in the next few hours.
This should relegate any isolated flash flooding concerns to areas
along and just north of the I-10 corridor in the Florida
Panhandle.

Asherman

Day 2
Valid 12Z Fri May 08 2026 - 12Z Sat May 09 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM SOUTH TEXAS
GULF COAST THROUGH THE LOWER MISSISSIPPI VALLEY...

The synoptic pattern on Friday will characterized by the return of
deep moisture as a previously stalled front, lingering along the
Gulf Coast begins to lift northward as a warm front. Near the
front, PWs are forecast to approach 1.8-2 inches (near the 99th
climatological percentile) from South Texas through the lower
Mississippi Valley, providing an ample reservoir for heavy
rainfall. This moisture, along with an upper level low moving into
West Texas and downstream shortwave are expected to support
numerous showers and storms with the potential for heavy rates.
However, the exact placement of the heaviest rainfall within the
broad QPF footprint on Friday remains nebulous, with several
separate rounds of thunderstorms possible throughout the Day 2
period. When considered with high 1-3 hour FFGs across much of the
region, the Marginal Risk was left intact for this cycle. An
embedded Slight Risk remains possible in subsequent updates should
a focused signal for heavy rainfall emerge over a more sensitive
area.

Asherman/Pereira

Day 3
Valid 12Z Sat May 09 2026 - 12Z Sun May 10 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
THE LOWER MISSISSIPPI VALLEY AND THE CENTRAL GULF COAST...

The previously noted upper-level low moving across Texas on Day 2
will continue to eject eastward toward the central Gulf Coast --
de-amplifying as embeds within the base of a broad upper-trough
centered over the Upper Great Lakes. Deep moisture lingering ahead
of the wave and associated stationary front will fuel shower and
storm development capable of producing heavy rainfall. Similar to
Day 2, however, confidence was lacking for any upgrades beyond a
Marginal Risk within the broad precipitation footprint. However,
should the models start to move into better agreement, an upgrade
may be warranted in future updates -- especially if the guidance
begins to show a growing signal for heavy amounts across areas
impacted by recent heavy rains. For now, modest adjustments were
made to the Marginal Risk area to account for the potential overlap
of heavy rainfall in portions of central AL.

Asherman/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