Subj : HVYRAIN: Excessive Rainfall Discussion
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Nov 13 2022 15:08:09

FOUS30 KWBC 131508
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1007 AM EST Sun Nov 13 2022

Day 1
Valid 12Z Sun Nov 13 2022 - 12Z Mon Nov 14 2022

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

Snell/Cook




Day 2
Valid 12Z Mon Nov 14 2022 - 12Z Tue Nov 15 2022

....THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL ACROSS THE
UPPER TEXAS COAST AND CENTRAL GULF COAST...

By Monday, return flow out of the western Gulf of Mexico ahead of
an approaching vigorous shortwave over the southern Plains will
set the stage for potentially excessive rainfall extending from
the Upper Texas Coast to southern Louisiana and potentially
southern Mississippi and Alabama by the late evening hours. PWATs
over 1.5" and dew points into the 60s are forecast to push just
inland with the help of a slow-moving warm front and 50 kt
low-level jet. This moisture source will be short-lived and
struggle to push well inland as a fast moving cold front kicks the
convection eastward Monday night. The best intersection of
instability, moisture, and shear along the warm front is likely to
be near the Upper Texas Coast and far southwestern Louisiana.
Current QPF depicts widespread 1-3" rainfall amounts are possible
within much of the Marginal Risk area and could reach locally
higher. However, given the best instability remains right along
the coast and over the northern Gulf of Mexico, there remains some
notable questions regarding how far inland the heaviest rain will
reach. This is especially important from a flash flood forecasting
standpoint as most of these coastal regions are marshy and
resilient to rainfall of this magnitude. Urban areas are most at
risk given the naturally lower threshold for flash floods and
ponding water over impervious surfaces. Elevated convection is
likely farther north into the Lower Mississippi Valley as well,
where 1" rainfall totals could be realized, but should remain
under FFG. The only change to the updated outlook was to extend
the Marginal Risk farther west along the Upper Texas Coast to
capture the HIRES CAM guidance depiction of the early onset
convection.

Snell

Day 3
Valid 12Z Tue Nov 15 2022 - 12Z Wed Nov 16 2022

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

Snell



Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!5SAGZv9BDyHnt3MA99c4xP89cnCl50LqIIY4N71qHm09=
udIBH-gWrQXPx9Yxl6YgMHjGWT8VpirciYGzolE1JZgkRF4$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!5SAGZv9BDyHnt3MA99c4xP89cnCl50LqIIY4N71qHm09=
udIBH-gWrQXPx9Yxl6YgMHjGWT8VpirciYGzolE1pQ-6_4A$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!5SAGZv9BDyHnt3MA99c4xP89cnCl50LqIIY4N71qHm09=
udIBH-gWrQXPx9Yxl6YgMHjGWT8VpirciYGzolE1K2XleaM$=20


$$



=3D =3D =3D
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