FOUS30 KWBC 090823
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
423 AM EDT Thu Apr 9 2026

Day 1
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, LOWER MISSOURI AND MID-MISSISSIPPI VALLEYS AND
ALONG THE EAST COAST OF FLORIDA...

...Central Plains to Mid-Mississippi Valley...
The surface frontal boundary stretching from the Central Plains
into the Mid Mississippi Valley is expected to be nearly stationary
day 1, remaining oriented in a general west to east direction.
In the wake of the strong height falls moving northeast from the
Upper Lakes into southeast Canada, additional shortwave energy
expected to dive southeast from the Northern Plains into the Upper
MS Valley. These height falls will help strengthen the low level
south southwesterly flow into this boundary, push PW values to 1
to 2+ standard deviations above the mean and enhance uvvs in the
above average PW axis in the vicinity of the stationary front. This
will support increasing convection late Thursday afternoon into
the early hours of Friday in the vicinity of this boundary with
locally heavy rainfall totals and isolated runoff issues. Only
some minor changes made to the previous marginal risk area,
trimming it to the northwest across northern IL, and extending it
slightly farther south into northeast KS to match the latest model
qpf consensus. The marginal risk fits well with where the latest
HREF neighborhood probabilities are highest for 1 and 2"+ totals
during the upcoming day 1 period.

...East coast of Florida...
The strong low level east northeasterly flow will continue for at
least the beginning of the day 1 period along the east coast of
Florida. PW values will remain above average during the day on
Thursday, before beginning to decrease as the low level onshore
flow weakens after 0000 UTC Friday. There will continue to be the
threat of locally heavy rains from slow moving to nearly stationary
rain bands in this strong moist onshore flow region. Confidence is
not great with placement, leading to little in the way of changes
with to the previous broad marginal risk area along the east
central to southeast Florida coastal region, with the greatest risk
of runoff issues in more urbanized regions.

Oravec


Day 2
Valid 12Z Fri Apr 10 2026 - 12Z Sat Apr 11 2026

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

The west to east front stretching from the Central Plains into the
Mid-Mississippi Valley day 1 will begin to push southward late day
1 into early day 2. This front will then again becoming stationary
during the day on Friday, oriented west to east from the Central
Plains, east into the Lower MO Valley and Mid-Mississippi Valley.
Similar to the day 1 period, PW values should increase in the
vicinity of this front in response to strengthening southerly low
level inflow. Shortwave energy pushing northeastward into this high
PW axis in the vicinity of this front will support areas of slow
moving convection along this front, locally heavy rains and
isolated runoff issues. The previous marginal risk area was pushed
southward by approximately 50-75 miles to fit the latest model qpf
consensus. There still is some latitudinal spread with the max qpf
axis, with the more southern solution favored in the latest WPC qpf.

Oravec


Day 3
Valid 12Z Sat Apr 11 2026 - 12Z Sun Apr 12 2026

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

An axis of much above average PW values expected to increase in
size day 3 across the Southern to Central Plains, into the Upper
MS Valley in a region of strengthening south southwesterly to
southwesterly low to mid level flow. There is the likelihood of
numerous shortwaves moving northeastward in this mid level
southwesterly flow across the mid section of the nation, supporting
increasing precip chances/coverage across this region. There still
is a large spread in the models with respect to placement of max
qpf, leading to low confidence at the moment for the day 3 time
period. Given the model spread and dry antecedent soil moisture and
high FFG values, the risk area was maintained at marginal, with
the potential for upgrade to slight in subsequent model cycles if
better agreement with max qpf axes occurs.


Oravec
$$
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 * Origin: Project Scorpio TEST (618:250/6)