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FOUS30 KWBC 090752
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
252 AM EST Fri Jan 9 2026

Day 1
Valid 01Z Fri Jan 09 2026 - 12Z Fri Jan 09 2026

..THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE TENNESSEE AND LOWER MISSISSIPPI RIVER VALLEY...

The classic synoptic setup for a winter flash flooding event
continues to slowly adjust to the timing/orientation of the
upstream shortwave over the Southwest U.S. The very strong leading
cyclone across the Great Lakes will continue to zip along to the
east-northeast with well above normal (4 Standard Anomaly/99th=20
percentile) moisture and flux still streaming across the Ohio and
Tennessee Valley. Ongoing thunderstorms are expected across the
Lower MS Valley as morning surge of Gulf air streams northward
becoming increasingly confluent/convergent well ahead of the
upstream synoptic front in the Plains.=20

The strong upstream base of the positive tilt trof will be
advancing throughout the day into the Plains, though the upper-
level jet streak also be expanding and strengthening across the
Ozark Plateau into the Ohio River Valley from 110kts to over 150kts
by the end of the forecast period. The trough will also be shearing
into the confluent, increasingly unidirectional low to mid-level
flow allowing for a deep southwest to northeast atmospheric river
from the western Gulf up the Lower Mississippi and through the
Tennessee River Valley into the southern Appalachians/Cumberland
Plateau through the majority of the day. While the low level flow
will be weaker than Thursday, 850-700mb 40-45kts and 1.5-1.75"
total PWat values will allow for high moisture flux convergence and
support efficient rainfall production.

As the trends have slowed the upstream shortwave, this allows for
greater flux of unstable air northward and forcing to
overlap/intersect with 1000-1500 J/kg of MLCAPE across the Coastal
Plain reducing toward 500 J/kg near the southern TN border, pulsing
with northward surges as the shortwave lifts out. This will provide
enough ascent and low level shear for organized bands of
convection that will likely have training elements throughout the
day. Rain-rates of 1.5"/hr are probable though 00z Hi-Res CAMs
support occasional up-ticks to 2"+/hr locally. Combined with the
training profiles, 00z HREF shows solid 15-25% 3"/3hr probability
across Southern MS into far northeast LA, with nearly 50%
neighborhood probability of 5". As such, and in coordination with=20
local forecast offices, WPC is introducing a small Moderate Risk of
Excessive Rainfall for S MS and adjacent NE LA. It should be=20
noted, there is solid agreement within the guidance suite of 5-8"=20
total streaks but there is limited agreement in the placement=20
particularly west or east.

Thunderstorms will train, but as they move northeast into Middle to
eastern TN and northern and central AL, intensity and rainfall
totals are likely to diminish, given instability will be limited=20
to 200-300 J/kg. Yet, prolonged duration and sizable totals of 2-4"
are still possible and so the Slight Risk continues to be in place
downstream across much of AL, northern GA, and southeast TN.=20

Upstream, as the main forcing exits, a secondary axis of
convergence along instability/moisture gradient across eastern
Texas will produce additional, slightly more elevated
thunderstorms. Similar rates of 1.5" to 2"/hr are possible with
some repeating/training tracks across NW LA, though overall
duration and coverage should limit rainfall totals to 2-4" relative
to the Moderate Risk area further southeast. As such, the Slight
Risk was also expanded westward along the axis of best overall
model agreement.=20

Gallina

Day 2
Valid 12Z Fri Jan 09 2026 - 12Z Sat Jan 10 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHERN APPALACHIANS...

Heavy rainfall early in the period is expected over what should be
at least partially saturated ground across portions of the
Southern Appalachians before heavy rainfall ejects into the
southern Mid-Atlantic States. Added a Marginal Risk as a=20
precaution for this reason; the threat not expected to persist past
18z Saturday.

Roth/Gallina


Day 3
Valid 12Z Sat Jan 10 2026 - 12Z Sun Jan 11 2026

The probability of rainfall exceeding flash flood guidance is less
than 5 (five) percent.=20

Gallina


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!4EP53CkbZZfXYEVFrWeFDFftkdO_L0ps9pa6o-jzdb11=
UPyTzBfkecUbxka-iEXXSqj7zSQYowqTOh9TrFZnINF_jW8$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!4EP53CkbZZfXYEVFrWeFDFftkdO_L0ps9pa6o-jzdb11=
UPyTzBfkecUbxka-iEXXSqj7zSQYowqTOh9TrFZnX70BIG0$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!4EP53CkbZZfXYEVFrWeFDFftkdO_L0ps9pa6o-jzdb11=
UPyTzBfkecUbxka-iEXXSqj7zSQYowqTOh9TrFZnfZJnab0$=20

=3D =3D =3D
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