Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1206 PM EDT Thu Sep 3 2026
Day 2
Valid 12Z Fri Sep 04 2026 - 12Z Sat Sep 05 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
ARIZONA AND NEW MEXICO...

...Southwest...

PW anomalies raise back to 2-2.5 standard deviations above normal
during this period. Still remains to be seen how much influence
the eventual tropical system that ultimately pulls west of Baja
will have in terms of the upper level moisture (potential uptick in
the PW anomaly). A Slight Risk was maintained for Arizona while a
broad Marginal covers southeast California the Four Corner as this
is where the signal for better moisture/instability axis aligns.
Isolated to scattered flash flooding is expected.

...Gulf states...

Lingering moisture and instability along this corridor could
result in a continued localized flash flood risk. A Marginal Risk
was maintained from eastern Texas to southern Georgia and Florida.

...Upper Midwest/Ohio Valley/Central Appalachians...

Additional organized/widespread convection to develop downwind of
the upper ridge axis today. Precipitable water values are high
enough with sufficient instability that embedded cells could
produce local downpours and isolated flooding. This will likely
start over eastern portions of the Upper Midwest, where the upper
jet streak to the northeast is expected to strengthen as the
pivoting northern stream trough impinges on the broad-scale ridge
to the south. Have essentially traced the Marginal Risk area
southeast along the mean 850-300 mb thickness fields, where the
upper level forcing along/ahead of the surface front will be most
supportive of more organized activity. A Marginal Risk is in effect
from Wisconsin to Virginia and eastern North Carolina.

Campbell/Chenard


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