Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
154 PM EST Wed Jan 7 2026
Day 3
Valid 12Z Fri Jan 09 2026 - 12Z Sat Jan 10 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE TENNESSEE VALLEY AND DEEP SOUTH...

...21Z Outlook Update...
A few modifications were made to the Marginal and Slight Risk
areas - mainly to trend southward and slightly westward per 12Z
guidance. These expansions now include Birmingham, AL and Jackson,
MS metropolitan areas. QPFs have increased in these areas, and the
nature of the forcing/ascent suggests potential for a few storms to
train. Additionally, storms may focus along a warm front oriented
east to west across the region, but models are generally uncertain
on where this front will reside when the bulk of the convection
moves through the risk areas. Furthermore, mesoscale details are
unclear and outflows/convective augmentation of the warm front are
all possible. Potential is there for a localized region of 5+
inches of rain during the forecast period but with details
remaining unclear, holding at Slight/Marginal seems to be the best
course of action. Ground conditions are quite dry, which lends some
uncertainty on the ground impacts/flash flood potential but if
enough rainfall occurs on a localized basis, that aspect of the
forecast may not matter as much.

See the prior forecast below for additional information.

Cook

...Previous Discussion...

Large scale amplification of a trough over the Central Rockies into
the Central Plains will generate a broad axis of ascent from the
Mississippi Valley to points eastward with a cold frontal
progression slowly migrating east across the aforementioned areas.
Meridional component of the pattern evolution will benefit from the
strengthening mean trough with multiple shortwave ejections
rounding the trough base across the Lower Mississippi Valley,
advancing northeast through the Southeastern U.S. before migrating
into the Tennessee Valley by the end of the D3. Deep moisture plume
ahead of the trough will usher anomalous PWATs on the order of +2
to +4 sigma spanning east TX through much of the Southeast into
the Southern Ohio Valley. Ample shear and deep moist axis will
maintain a prevalent fixture for much of the period with flow
running close to, if not parallel to the frontal axis that will
bisect southwest to northeast across the Lower Mississippi Valley
through Central and Northern MS/AL into TN. Current ensemble trends
favor a rather broad axis of 2-3" precip totals just within the
means with the deterministic output pushing closer to 4-5" with the
maxima focused over central MS up through northern AL to south-
central TN. This aligns well with the pattern evolution progressing
the front into those confines with a multi-wave ejection riding
into the front as they eject out of the broad deep-layer
southwesterly flow situated across the region.

This setup is classic for a winter time flash flood prospect across
this area of the CONUS as broad ascent coupled with ample deep-
layer shear and highly anomalous moisture tends to amplify the
threat for heavy rainfall repeating over the same areas. This is
being forecast within the Southeast and far southern edge of the
Ohio Valley with the ensemble overlap generally in that corridor
from east-central MS to points north and east with a maxima
oriented over northern AL into southern TN. This is likely the area
to watch, however don't be surprised if areas south across the
southern half of MS into parts of LA see a greater heavy convective
signature that tends to crop up in the short range as the
instability maximum tends to verify a bit further south compared
to what global deterministic output has at this lead. For now,
maintained general continuity in the grand scheme, but adjusted the
SLGT and MRGL risks based on QPF trends and alignment with the
greatest potential for training, and elevated theta_E placement.

Kleebauer

Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt