Subj : HVYRAIN: Excessive Rainfall Discussion
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Wed May 10 2023 07:24:35

FOUS30 KWBC 100724
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
323 AM EDT Wed May 10 2023

Day 1
Valid 12Z Wed May 10 2023 - 12Z Thu May 11 2023

....THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL NEAR THE
TEXAS/LOUISIANA BORDER...=20
=20
....Western Gulf Coast across AR...=20=20
The combination of a mid-level low moving north out of TX into the
Midwest and an incoming closed cyclone moving through the West
should set the stage for good moisture transport through the
Plains, divergent flow aloft, strengthening low-level
inflow/effective bulk shear, and sufficient instability for
organized convection.  To the south of the lifting upper level
low, training and efficient bands of convection are expected from
the Middle and Upper TX coast north-northeast through the Sabine
River into far southwest AR.  The reconfigured Moderate Risk area
was coordinated with the HGX/Houston-Galveston TX, LCH/Lake
Charles LA, SHV/Shreveport LA, and LZK/Little Rock AR forecast
offices.  The mesoscale guidance shows that portions of the Middle
and Upper TX Coast should be receiving heavy rainfall at the
beginning of the period in an area where a CAPE gradient should be
lifting north within a warm advection pattern behind the departing
upper low.  The 00z HREF shows non-zero chances of 3"+ in an hour
and 8"+ in 24 hours within the Moderate Risk area, which should be
a morning event primarily in Southeast TX and occur during daytime
heating into the overnight hours for places farther north.  The
Slight Risk area has been expanded across much of AR -- local
Moderate Risk impacts are possible Wednesday night into early
Thursday where any efficient, training bands manage to form.
=20=20
....Central High Plains/Northern Plains...
A combination of upslope flow and some low- to mid-level
frontogenesis acting in concert with sufficient instability should
lead to heavy rainfall.  Heavy rain which has occurred the past
several days keeps portions of southern NE and northwest KS in the
Marginal Risk.  Precipitable water values near or above 1" in the
High Plains are a big deal from a heavy rainfall perspective.=20
Closer to the 850 hPa low in WY/MT, the guidance has a strong
signal for local 2" amounts...local amounts to 4" can't be ruled
out.  There has been some reduction to the size of the Slight Risk
to follow the trend seen on the most recent guidance.
=20
Roth=20


Day 2

The Day 2 outlook will be updated by 0830Z.


Day 3

The Day 3 outlook will be updated by 0830Z.


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!5rT3Y-oWB8tWNxqWa00G_ukAzqxbzsHoEMugxFm8DW2Z=
q5DLtrySTSRIEjdPGCcfHTpElWvC09aW3wdiQ2uP2RG3M7E$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!5rT3Y-oWB8tWNxqWa00G_ukAzqxbzsHoEMugxFm8DW2Z=
q5DLtrySTSRIEjdPGCcfHTpElWvC09aW3wdiQ2uP4yZeNgw$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!5rT3Y-oWB8tWNxqWa00G_ukAzqxbzsHoEMugxFm8DW2Z=
q5DLtrySTSRIEjdPGCcfHTpElWvC09aW3wdiQ2uPakL9oC4$=20


$$



=3D =3D =3D
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