FOUS30 KWBC 082008
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
408 PM EDT Wed Apr 8 2026

Day 1
Valid 16Z 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 north of a stationary front near the Florida Keys
will lead to another round of scattered convective activity from
this afternoon into the evening, 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 southern Brevard
County, along the Treasure Coast, and southward to the Fort
Lauderdale and Miami metros.

The ensemble bias corrected mean is showing QPF magnitudes of 2-4
inches from Melbourne to Miami. Meanwhile, the high resolution
ensemble neighborhood probabilities are showing high chances
(60-90%) of rainfall exceeding 3 inches between the cities
mentioned above. A medium chance (40-70%) for exceeding 5 inches
is modeled farther south from the Treasure Coast to Fort
Lauderdale/Miami. Lastly, on the higher end of rainfall outcomes,
there is around a 20-40 chance of nearing 8 inches of rainfall by
Friday morning centered around Broward County to northern Miami.
Bottom line, moisture convergence along the central and
southeastern Florida coastline, combined with the potential for
training storm motions, may lead to chances for flash flooding.
This is especially true if the isolated higher end rainfall
amounts are realized over sensitive urban areas. As a result, a
Slight Risk for Excessive Rainfall is in effect from southern
Brevard County to the Miami metro.


Wilder


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
MID-MISSISSIPPI VALLEY,CENTRAL PLAINS, AND THE EAST COAST OF
FLORIDA...

...Central Plains to Mid-Mississippi Valley...

20Z Update: The general synoptic pattern remains consistent on a
run-to-run basis. That means there is the potential for locally
heavy rainfall that produces isolated 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 stalling frontal boundary across the Upper Midwest and
Northern Plains. This will focus an axis of ascent along and just
ahead of the front. 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. One adjustment in the afternoon
package was a minor expansion of the MRGL risk north and eastward
to include the city of Des Moines. This is mostly a result of
uncertainty in QPF location as a result of differences in where the
stationary front aligns.


...Florida...

20Z Update: A threat for showers and thunderstorms will linger
from the Space Coast southwards to the Miami metro. The risk for
flash flooding should lessen on Thursday, but the overall pattern
of relatively high PWATS, moisture advection and convergence along
the coastal corridor should support an additional 1-3 inches of
rainfall. Moreover, saturated soils along the Space Coast to South
Florida may increase susceptibility to flash flooding. Therefore, a
Marginal Risk for Excessive Rainfall is in effect from the
northern Space Coast to Miami.

Wilder/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...

20z Update: The general forecast remains on track as moisture
convergence along a slow moving cold front will help initiate
another round of heavy rainfall for portions of the Central Plains
to the Mid-Mississippi Valley.

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/Wilder


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