FOUS30 KWBC 080825
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
425 AM EDT Wed Apr 8 2026

Day 1
Valid 12Z Wed Apr 08 2026 - 12Z Thu Apr 09 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE EASTERN FLORIDA PENINSULA...

A persistent pattern of northeasterly flow into the eastern FL
Peninsula along with a quasi-stationary front bisecting portions of
the state will lead to another round of scattered convective
activity starting later today which may produce localized flash
flooding. The best chance for this to occur will be across the
urban settings along the I-95 corridor stretching from Daytona
Beach down to the Miami metro with the latest HREF blended mean QPF
generally heaviest near the Treasure Coast where convergence along
the stationary front. This should serve as an anchor point for
storms. Other prospects for heavy rain will likely be along the
immediate coast due to frictional convergence spurred by the
prevailing northeasterly surface flow coupled with a moderate
effective shear layer between 30-40kts in an environment
characterized by CAPE values in the 1000 to 2000 J/kg range.

Areal neighborhood probabilities from the HREF and RRFS for >3"
remains very similar to values on Monday along a majority of the
eastern peninsula coast line. Suspect the RRFS was a bit too
excitable with its areal extent and neighborhood probabilities
although not entirely not of the realm of possibilities.
Precipitable water values will remain 1 to 2 standard deviations
above normal over the southern half of FL which would be sufficient
for those heavier cores to materialize when convection occurs.

Considering some overlap over the past few days, maintained the
Slight risk area introduced on Monday.

Bann


Day 2
Valid 12Z Thu Apr 09 2026 - 12Z Fri Apr 10 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PARTS OF THE
CENTRAL PLAINS AND SOUTHERN FLORIDA PENINSULA...

...Plains...
The general synoptic pattern across the Central CONUS
remains consistent on a run-to-run basis. That means there is the
potential for locally heavy rainfall that produces isolate flash
flooding from Kansas to points northeastward into northern Illinois
from late Thursday into Thursday night and early Friday morning.

A weak shortwave ejecting out of the Central Rockies will
intersect a slow-moving cold front propagating out of the Upper
Midwest and Northern Plains creating a focused axis of ascent along
and just ahead of the front as it migrates through the Plains and
Central Midwest. Areal QPF average of 1-3 inches remains in the
forecast within vicinity of the front with much of the rain
occurring in a window between 10/00Z and 10/12z Friday as return
flow from the Gulf approaches the front. The magnitude of rainfall
and antecedent soil moisture anomalies pin this into the
traditional MRGL risk threshold.

...Florida...
A threat for showers and a few thunderstorms will linger across
portions of the southern Florida peninsula on Thursday before the
system moves away from the area completely. The 08/00Z NCEP
guidance still generated isolated maximum areal-average QPF in
excess of an inch over the highly urbanized corridor. Felt it was
too early to remove the excessive rainfall area at this point.

Bann


Day 3
Valid 12Z Fri Apr 10 2026 - 12Z Sat Apr 11 2026

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

The southward moving cold front which is expected to serve as a
focus for some heavy rainfall on Thursday will continue to move
southward and once again be the focus for convection that may
produce excessive rainfall on Friday over portions of the Central
or Southern Plains. The airmass will be moderately unstable with
MUCAPE values peaking in the 1000 to 1500 J/kg range in area where
precipitable water values peak close to 1.5 inches on Friday
afternoon...which should foster decent rainfall rates and the
potential for excessive rainfall amounts.

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