Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
426 AM EDT Mon Sep 7 2026
Day 2
Valid 12Z Tue Sep 08 2026 - 12Z Wed Sep 09 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER IOWA...

...Upper Mississippi Valley into the Upper Lakes...
The surface front pushing east into the Northern Plains day 1 will
remain very progressive day 2 into the Upper Mississippi
Valley/Upper Lakes. The progressive nature of the front will
continue to be a detriment to widespread runoff issues. However,
the southwestern portion of this front will slow somewhat compared
to the farther northern portion in the vicinity of eastern NE
/northeast Kansas, east into Iowa. Across these regions there is a
better chance of a period of training of cells late Tuesday/early
hours of Wednesday. This is shown in the latest guidance that has
consensus for a heavier axis of qpf here. A small slight risk area
was added across portions of central to southern Iowa for this
training potential. RRFS neighborhood probabilities are fairly high
for 1 and 2"+ amounts across the slight risk area, with a smaller
50%+ probability for 3"+ amounts over east central Iowa.

Marginal risk areas

..Eastern Arizona into western to central New Mexico...
No significant changes day 2 to the axis of above average PW
values extending from eastern portions of Arizona into western to
central New Mexico. Continued low confidence with qpf details, but
potential for another round of widespread scattered convection
across this area. Locally heavy rain and isolated runoff issues
again possible. Anomalous PW values also expected to push farther
north from Southern CA into Central CA. At the moment, models are
not showing precip developing day 2 in this anomalous axis.

The previous marginal risk area over northeast Montana was removed
given latest model qpf consensus. The broad marginal was also
removed along the Gulf coast into FL given less organized precip
than day 1

Oravec


Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt