FOUS30 KWBC 031951
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
351 PM EDT Sun May 3 2026

Day 1
Valid 16Z Sun May 03 2026 - 12Z Mon May 04 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE SOUTHEAST FLORIDA PENINSULA...

16Z update... Redevelopment of convection expected roughly in the
18Z-01Z window to pass through over the urban corridor with hourly
rates up to 2 inches/hours. This will maintain an elevated threat
for excessive rainfall and isolated areas of flash flooding. The
northern edge of the Marginal was extended northward to cover most
of Palm Beach County.

Campbell

Just enough of a signal in the 03/00Z CAMS to maintain the Marginal
Risk area. The focus will be over the urban southeast coast as a
front advances into a region of deeper moisture and where CAPE
tends to be under 1000 J per kg. The 03/00Z HREF does depict a
low-end neighborhood probability of FFGs being exceeded over the
southern tip of the Florida peninsula in the 03/21Z to 04/00Z
period but the stronger signals in the guidance is for heavier
rainfall to be hugging the coast or remaining just off-shore. It
was noted that over the past couple of days...numerical models have
been cutting back the amount of moisture in the lowest layers which


Bann

Day 2
Valid 12Z Mon May 04 2026 - 12Z Tue May 05 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Campbell

Day 3
Valid 12Z Tue May 05 2026 - 12Z Wed May 06 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE MID MISSISSIPPI VALLEY INTO THE OHIO VALLEY...

21Z update... No adjustments were made to the current Marginal Risk
area. Still expecting a southwest to northeast axis of rainfall to
align ahead of and along a cold front from Arkansas to western New
York. Areal averages of 1 to 2.5 inches with the higher end
generally focusing within the Ohio Valley. In general this will be
a beneficial rain however there may be isolated areas where
rain rates lead to local flash flooding.

Campbell

Deep layer southwesterly flow leading into the start of the period
will be drawing moisture into parts of the Plains and then
downstream toward the Great Lakes and the Ohio Valley. As a trough
amplifies over the central part of North America and a jet streak
forms over the Southwest US and approaches the Plains...the chance
for showers and thunderstorms increases along and ahead of a
develops surface front. With precipitable water values of 1.75 to
1.9 inches embedded within a broader 1.5 to 1.75 area...which was
pushing two standardized anomalies greater than climatology for
this time of year--locally heavy rainfall and the associated risk
of localized flooding from late Tuesday afternoon into early
Wednesday is possible.

Bann


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