Subj : HVYRAIN: Excessive Rainfall Discussion
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Jan 30 2023 15:36:51

FOUS30 KWBC 301536
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1036 AM EST Mon Jan 30 2023

Day 1
Valid 16Z Mon Jan 30 2023 - 12Z Tue Jan 31 2023

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

Mullinax


Day 2
Valid 12Z Tue Jan 31 2023 - 12Z Wed Feb 01 2023

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

Chenard

Day 3
Valid 12Z Wed Feb 01 2023 - 12Z Thu Feb 02 2023

....THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
EASTERN TX AND NORTHWEST LA...

Multiple rounds of rain will impact portions of TX into the lower
MS Valley over the next 3 days. In general instability will be
limited, and surface temperatures in the 30s and 40s doesn't
scream flash flood potential. However, with some of the area
seeing heavy rain Sunday, and additional rounds of rainfall
expected over the next 3 days, soil conditions over the area will
become more sensitive by Wednesday. Also, by Wednesday into
Wednesday night we do start to see some better large scale forcing
over the area, with troughing approaching from the west, an upper
jet to the north and increasing low level moisture transport.
While instability will remain low, some weak elevated instability
combined with the uptick in forcing/moisture should still support
some convective elements and potentially rainfall rates ~1" in an
hour.

Despite some model differences on the details, the 00z GEFS and
ECENS were in above average agreement on the placement of higher
rainfall probabilities. Taking this consensus area and accounting
for the expected location of weak elevated instability and
stronger forcing led to the placement of the Slight risk from east
TX into western LA. The Slight risk was reduced in size and
shifted a bit south of continuity with this update...generally
keeping it where both the GEFS and ECENS show a chance of 2-3"+ of
rainfall over the next 3 days, and covering spots that were hit
hard with rain on Sunday.

The magnitude of the flash flood risk remains a bit uncertain
given the aforementioned question regarding instability and thus
rainfall rates. The thought is that this is probably on the lower
end of the Slight risk probability range at this point...but the
prolonged rainfall leading to more sensitive soil conditions
combined with the uptick in forcing/rainfall rate potential by
Wednesday supports the continuation of the Slight risk. The north
and northwest extent of the Marginal risk was cut back...as
freezing rain will likely be the bigger concern here.

Chenard


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!8JdV1XPegr2hMx8qrNlOrnHle1rUXZGHPNSryEbHfD7a=
VkF5UIg0YyU9WogeaCJ3M7kpdgnUVL9iSq2hw0P5RtnADpo$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!8JdV1XPegr2hMx8qrNlOrnHle1rUXZGHPNSryEbHfD7a=
VkF5UIg0YyU9WogeaCJ3M7kpdgnUVL9iSq2hw0P5_YpmT44$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!8JdV1XPegr2hMx8qrNlOrnHle1rUXZGHPNSryEbHfD7a=
VkF5UIg0YyU9WogeaCJ3M7kpdgnUVL9iSq2hw0P5r51Ipv4$=20


$$



=3D =3D =3D
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