Subj : HVYRAIN: Excessive Rainfall Discussion
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Thu Dec 15 2022 01:00:25

FOUS30 KWBC 150100
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
759 PM EST Wed Dec 14 2022

Day 1
Valid 01Z Thu Dec 15 2022 - 12Z Thu Dec 15 2022

....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM PARTS OF THE
CENTRAL GULF COAST INTO THE SOUTHERN APPALACHIANS...

A SSW to NNE oriented axis of thunderstorms extended from the
central Gulf Coast at 0030Z, located just ahead of a cold front
that stretched southwestward from a triple point low in
northwestern Alabama into the Gulf. A robust shortwave advancing
quickly northeastward from the Missouri/Arkansas border has
allowed the cold front to move east at a progressive pace along
the Gulf Coast, limiting the degree of training that was observed
late Tuesday night across Louisiana and Mississippi.

However, moisture remained anomalous ahead of the cyclone with
precipitable water values near 1.1 inches along the Ohio River to
about 1.9 inches along the central Gulf Coast. Flow aloft remains
widely diffluent from the central Gulf Coast into the southeastern
U.S. to the southeast of a 120-140 kt upper level jet. A limiting
factor will be instability in which higher values are (and will
remain) confined to locations south of a warm front that is
forecast to lift northward across Georgia and the Coastal Plain of
South Carolina through 12Z. It is here that brief periods of
training may still support rainfall rates of at least 2-3 in/hr
(though remaining localized) if line orientation can match
steering flow out ahead of the cold front, but with the
probability of rainfall rates in excess of 2 in/hr lowering
through the night.

Farther north into the southern Appalachians and Ohio Valley,
rainfall rates are expected to max out in the 0.5 to 1.0 in/hr
range at best, but locations from the Ohio/Kentucky border into
east-central Tennessee have fairly low flash flood guidance values
of an inch or less in 3 hours.

Additional rainfall totals through 12Z Thursday are expected to
peak in the 2-4 inch range within the Slight Risk area with 1 to
1.5 inches from the upper Ohio Valley into the south-central
Appalachians. Along the Florida Panhandle, localized training
ahead of the cold front through the night may support a narrow
stripe of 3 to 4 inches of rain but flash flood guidance values
are high at 3-5 inches in 3 hours.

Otto



Day 2
Valid 12Z Thu Dec 15 2022 - 12Z Fri Dec 16 2022

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Campbell

Day 3
Valid 12Z Fri Dec 16 2022 - 12Z Sat Dec 17 2022

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Campbell


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!9cYb8d_U6_SUEHZfySfxKBlVbI5ooae1mKnCP0yZKot4=
9AU84rTK5GoxOV2Ix0wtSGg7kFLVCxJMlFXnRHRvUENRr1Q$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!9cYb8d_U6_SUEHZfySfxKBlVbI5ooae1mKnCP0yZKot4=
9AU84rTK5GoxOV2Ix0wtSGg7kFLVCxJMlFXnRHRvKQDAvQg$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!9cYb8d_U6_SUEHZfySfxKBlVbI5ooae1mKnCP0yZKot4=
9AU84rTK5GoxOV2Ix0wtSGg7kFLVCxJMlFXnRHRvvut7iK8$=20


$$



=3D =3D =3D
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