Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
343 AM EDT Mon Sep 15 2025
Day 2
Valid 12Z Tue Sep 16 2025 - 12Z Wed Sep 17 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHWEST, THE CENTRAL HIGH PLAINS, AND VIRGINIA/NORTH
CAROLINA...

...Southwest...

Scattered convective pattern will initiate on Tuesday afternoon and
early evening before fading with the loss of diurnal heating.
Current progs are for convection to be tied closer to the terrain
across southeast AZ into southern NM with isolated signatures of
>1"/hr plausible in the stronger cell cores. These areas generally
prone to runoff due to terrain complexities, as well as remnant
burn scars present in some locations. Maintained continuity from
inherited MRGL risk with some minor adjustments to remove El Paso
proper.

...Central High Plains...

Strong shortwave trough ejection out of the interior Northwest will
lead to convective development and regional enhancement across the
Central High Plains. Greatest ascent is aligned with the diffluent
region of the mid-level shortwave with left-exit region dynamics
likely to maintain a prevalent heavy rain signature across the
western third of NE down into neighboring northeast CO and
northwest KS. Heaviest rain could remain just outside of the risk
area according to some guidance leading to low probability of flash
flooding due to the occurrence within the western Sand Hills.
There's still a good agreement on localized maxima within the hi-
res ensemble means, pin-pointing the area west of North Platte, NE
as one of the favorable spots for convective impacts. FFG's in this
corridor are lower than the neighboring Sand Hill domain, so the
MRGL risk remains relatively small.

...Virginia and North Carolina...

Our surface low will mature and occlude by Tuesday afternoon as the
closed height fields indicate the 850/700/500 mb lows becoming
vertically stacked leading to a slow decay of the surface low by
the second half of the period. Persistent heavy rain potential will
linger across eastern NC up into the VA Tidewater leading to
multi-day totals reaching 2-4" with locally upwards of 6-7" over
the span of 48 hrs. Despite the drier soils leading into the event,
the cumulative effect will lead to areal flooding concerns for
portions of the above locations. Some westerly push of the heavier
QPF is progged in the front half of D2 leading to some areas in
north-central NC up through south-central VA possibly sneaking into
the flash flood threat. The only good news is the weakening surface
low will lead to degrading rates eventually, and slow wane on the
threat. The MRGL risk inherited was maintained with some minor
westerly expansions to account for recent trends in the ensemble
means.

Kleebauer


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