Subj : HVYRAIN: Excessive Rainfall Discussion
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Thu Jan 19 2023 00:41:04

FOUS30 KWBC 190040
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
740 PM EST Wed Jan 18 2023

Day 1
Valid 01Z Thu Jan 19 2023 - 12Z Thu Jan 19 2023

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE LOWER MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS...

0100 UTC Update -- Removed the Slight Risk area and pared the
western portion of the Marginal based on the observational and
mesoanalysis trends. Fairly narrow and disjointed Warm Conveyor
Belt (WCB) was noted per recent satellite IR loops. This as the
mid/upper level low over the Central Plains lifts into the Upper
Midwest overnight, with strengthening west-southwesterly 850-500
mb flow to the south helping to accelerate the eastward
progression of the surface front. The result is a narrowing line
of pre-frontal convection along a constricting axis of 1.5+ inch
PWs, with strengthening negative PW advection with time overnight
from west to east. This along with the marginal deep-layer
instability (MUCAPEs 500-1000 J/kg) will lead to decreasing hourly
rainfall rates...as the 18Z HREF 30%+ probabilities of >1"/hr
rates diminishing considerably in areal extent after 02-03Z.
Considering the current FFG, any rapid runoff or flash flooding
concerns are expected to be marginal or localized at most.

Hurley


Day 2
Valid 12Z Thu Jan 19 2023 - 12Z Fri Jan 20 2023

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.  An axis of moderate to heavy precipitation should
develop over New York State (beginning after 15Z) and southern New
England (beginning after 21Z).  Rates should stay below FFG
thresholds in most areas, and some of the heavier precip may fall
as ice or snow especially in central/northern New York.  At this
time, any flood/flash flood issues should be isolated at best (<5%
coverage).

Cook/Oravec

Day 3
Valid 12Z Fri Jan 20 2023 - 12Z Sat Jan 21 2023

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

Cook/Oravec


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!8fdJ_6AajG6ByJ82QnhPoblaMLw2jZfJ6ecUVSMWSPPI=
dbbZRU_8W14myotF-eWX3cne1PTRCLylMD2zFWfH9A6jqLs$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!8fdJ_6AajG6ByJ82QnhPoblaMLw2jZfJ6ecUVSMWSPPI=
dbbZRU_8W14myotF-eWX3cne1PTRCLylMD2zFWfHXTEjr6A$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!8fdJ_6AajG6ByJ82QnhPoblaMLw2jZfJ6ecUVSMWSPPI=
dbbZRU_8W14myotF-eWX3cne1PTRCLylMD2zFWfH5K00nEg$=20


$$



=3D =3D =3D
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