FOUS30 KWBC 020829
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
429 AM EDT Sun Aug 2 2026

Day 3  Valid 12Z Mon Aug 03 2026 - 12Z Tue Aug 04 2026

...THERE ARE MARGINAL RISKS OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHWEST, PLAINS AND MIDWEST, SOUTH FLORIDA AND THE EAST...

...Upper Ohio Valley/Cumberland Plateau/East...

Cool air aloft along with ample moisture and instability could
lead to hourly rain amounts up to 2.5 inches, which would be
problematic in rugged terrain, sensitive soils, and urban areas.
There is some overlap with areas that had rainfall during the Day 1
and 2 period, thus maintaining soil sensitivity for potential
flooding issues.

...Southwest/Southern High Plains...

A Marginal Risk for monsoonal convection across southern Arizona,
New Mexico, southern Colorado and into the Texas Panhandle was
maintained for this period. Locally heavy rains and isolated
runoff issues will be possible in the above average PW values
expected across this area.

...Central Plains into the Mid to Upper Mississippi Valley...

A slow moving front pushing through the Central Plains and
portions of the Mississippi Valley will trigger organized
convection for ahead along and ahead of the boundary. PW values
expected to be slightly above average...1.5 to 1.75"+ in the
vicinity of this front, supporting the potential of hourly rain
amounts to 2.5" where convection does organize and isolated runoff
issues. A Marginal Risk remains in effect for this part of the country.

...South Florida...

Onshore flow will trigger showers and thunderstorms capable of
producing 1 to 2+ inches of rainfall that may lead to isolated
flash flooding/ponding. A Marginal Risk area was raised for this period.

Campbell
 

Day 4 and Day 5  Valid 12Z Wed Aug 05 2026 - 12Z Fri Aug 07 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE MID TO UPPER MISSISSIPPI VALLEY/MID WEST...

...Mid to Upper Mississippi Valley/Mid West...
There is fairly good model qpf agreement on heavy precip potential
along and ahead of the cold front sinking southeastward day 4 from
the Upper MS Valley/Upper Lakes region. Favorable right entrance
region jet dynamics along the southern edge of the westerlies
should enhance uvvs in an axis of 1.75"+ PW values in the vicinity
of this front. There is a good chance of organized convection along
and ahead of the front Wednesday night into the early hours of
Thursday, with potential for localized runoff issues. The slight
risk area was drawn to encompass the model qpf axis consensus from
southern IA/far northern MO, eastward into northern IL/far southern
WI, including the Chicago metro area.

...Central Plains into the Lower Missouri Valley...
By day 5...additional shortwave energy moving along the southern
edge of the westerlies into the Central High Plains may ignite
another round of organized convection along the southward moving
cold front from KS into MO. Not as good of agreement model qpf wise
day 5 compared to day 4 farther to the northeast, but with low
level southerly flow expected to strengthen Thursday night into
early Friday morning into this front, locally heavy rains are
possible. At the moment, the risk level along the front over the
Central Plains toward the Lower MO Valley kept at marginal for day 5.

...Southern to Central Appalachians into the Northern Mid- Atlantic...
Whatever is left of the upper trof across the eastern U.S. by the
beginning of the day 4/5 time period, should continue to weaken.
However, an axis of high PW values...1.5-1.75"+, will remain across
much of the eastern U.S. in the Wednesday to Friday time frame.
This will support additional widespread scattered showers in this
high PW axis, with locally heavy rains and runoff issues possible.
A marginal risk was continued for both day 4 and 5 across the
Southern to Central Appalachians into the northern Mid- Atlantic.
After several days of locally heavy rains during the short range
period, FFG values will likely be lower through the Southern to
Central Appalachians into the Northern Mid Atlantic. This may
warrant a greater risk area across these regions with future updates.

...Southwest/Southern High Plains...
For the 1200 UTC Wednesday to 1200 UTC Friday time period,  a
marginal risk was depicted across much of AZ/NM for monsoonal
convection. Continued low confidence with qpf details here, but
locally heavy rains and isolated runoff issues possible in the
above average PW values expected across this area.

Oravec
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