Subj : HVYRAIN: Excessive Rainfall Discussion
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Tue Nov 15 2022 00:53:21

FOUS30 KWBC 150053
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
752 PM EST Mon Nov 14 2022

Day 1
Valid 01Z Tue Nov 15 2022 - 12Z Tue Nov 15 2022

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

01Z Excessive Rainfall Outlook...
No sizable changes were required with the update based on the 12Z
or 18Z guidance...including the 18Z HREF probability guidance...or
on trends seen in short-term radar/satellite imagery. So far, the
convection with the highest rainfall rates has remained off shore
from the Upper Texas coast and the models suggest that should
largely be the case as the convection makes its way eastward along
the Gulf Coast throughout the evening.  However, the strength of a
developing on-shore low-level jet riding up and over a surface
based warm front and the approach of surface low pressure along
the front all suggest that some inland expansion of the higher
rainfall rates could lead to isolated flooding...more so in urban
areas.=20

Plenty of moisture is in place with the 15/00Z soundings showing
precipitable water at or above 1.5 inches (including 1.79 inches
at KLCH) coincident with where satellite imagery was showing a
well defined wave racing along and immediately north of the
Louisiana coastline. The environment here was somewhat
unstable...with instability generally on the order of a few
hundred J per kg.  This should support a few thunderstorms capable
of producing rainfall rates >2"/hr into the overnight hours. The
14/18Z HREF does show 2"/hr rainfall probabilities as high as
30-50% along some portions of the Louisiana coast as early as
15/03Z.

Despite the favorable parameters for heavy rainfall, storm motions
will be quite progressive...which will tend to mitigate the flash
flooding threat except in more urbanized areas and poor drainage
areas that are already prone to potential flash flooding.

Bann




Day 2
Valid 12Z Tue Nov 15 2022 - 12Z Wed Nov 16 2022

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

Gallina


Day 3
Valid 12Z Wed Nov 16 2022 - 12Z Thu Nov 17 2022

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

Gallina



Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!6i3u-DjCp4sbRYcpnjh6xhr995pj2czRKC54FOPV772x=
F01QvkHiTV35bdVhomUrx6N1L62acquPvGcQsInhyNQR6Q8$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!6i3u-DjCp4sbRYcpnjh6xhr995pj2czRKC54FOPV772x=
F01QvkHiTV35bdVhomUrx6N1L62acquPvGcQsInh51etVDk$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!6i3u-DjCp4sbRYcpnjh6xhr995pj2czRKC54FOPV772x=
F01QvkHiTV35bdVhomUrx6N1L62acquPvGcQsInh8ApEUSM$=20


$$



=3D =3D =3D
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