Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
418 AM EDT Tue Sep 22 2026
Day 2
Valid 12Z Wed Sep 23 2026 - 12Z Thu Sep 24 2026

..THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF CENTRAL AND EASTERN NEW MEXICO...

...New Mexico and West Texas...
The heavy rainfall threat established on day 1 will continue and
potentially peak over NM on day 2 as large scale forcing gets even
stronger. A well defined mid level shortwave is forecast to lift
northward across the state, accompanied by robust upper level
divergence and the likely development of a surface low. PW values
will remain near record levels for this time of year, with an
anomalously deep moisture profile.

With such strong forcing and widespread moisture in place, the
primary limiting factor for heavy convective rates will be the
extent of cloud cover and its impact on destabilization. While
widespread clouds are a concern, daytime heating should allow at
least the eastern edge of the rainfall shield to sufficiently
destabilize, aided by broad easterly upslope flow. Thus while some
areas may see predominately stratiform rain, a concentrated swath
of intense convective rainfall remains likely.

As convection attempts to propagate eastward, strong easterly
inflow will act to slow this progression, increasing the threat of
training convective cells. Model guidance generally favors central
to eastern NM for the maximum QPF axis, as supported by the high
res 00z RRFS, REFS, FV3 and 3km NAM, and the global AIGFS and AIFS.
The 00z ECMWF remains the furthest west solution, and given the
expectation of some eastward convective propagation and instability
advecting in from the east, its maximum QPF placement is
probably too far west.

Only minor changes were made to the inherited Moderate risk area.
High res guidance supports localized swaths of 3 to 5 inches of
rain, which appears plausible given the environmental ingredients
in place. Scattered to numerous instances of flash flooding are
anticipated, and locally significant, life-threatening impacts are
possible...particularly across sensitive terrain, urban areas and
burn scars.

...Mid-Atlantic...
A complex synoptic pattern will be present over the eastern U.S. as
a mid to upper level low slowly drifts from the Ohio Valley
towards the Mid-Atlantic, while a separate coastal low develops
offshore. Meanwhile, surface high pressure positioned to the north
will advect drier and more stable air into the corridor between
these two features.

Much of the deepest moisture and instability will remain offshore
with the coastal low. The primary threat for heavy rainfall over
land should focus closer to the cold core of the upper low from
the OH Valley down through western NC and into north GA. While PW
values will have lowered across this area, model guidance still
indicates CAPE exceeding 1000 J/kg within a trough axis over the
region.

This localized axis of instability, coupled with a stationary
convergence axis, will support the development of slow moving
convective cells. Even with the reduction in deep moisture, locally
heavy rainfall rates are likely. Given that at least some of this
region will have compromised FFG and heightened hydrologic
sensitivity from previous rainfall, some flash flood risk is
expected to continue.

Based on signals from the 00z REFS and HREF members, as well as
the GFS and ECMWF, a small Slight risk has been introduced
stretching from eastern TN into eastern KY and southern WV, where
the focus for slow moving convection is expected to be greatest.

...Florida...
A Marginal risk continues across south FL where above normal PWs
and instability will continue to pose a localized flash flood
risk.

Chenard


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