Subj : HVYRAIN: Excessive Rainfall Discussion
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Oct 25 2024 00:58:36

FOUS30 KWBC 250058
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
858 PM EDT Thu Oct 24 2024

Day 1
Valid 01Z Fri Oct 25 2024 - 12Z Fri Oct 25 2024

....THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE MIDDLE MISSISSIPPI VALLEY...

....0100 Update...
Few changes made to the Day 1 ERO, based on the latest
observational data and trends (radar, satellite, mesoanalysis,
etc), along with the latest HRRRs and 18Z HREF probabilistic
guidance. Strengthening southwesterly low-level flow (40-50 kts at
850 mb) this evening will usher in PWATs to near 1.25" (well above
the 90th percentile, per SPC sounding climatology), along with=20
sufficient instability (ML CAPE 1000+ J/kg) and forcing (potent=20
shortwave trough crossing the Central Plains) for convective=20
development. Strong vertical shear (~50 kts) with idealized curving
hodographs will likely favor discrete convection (with both the=20
mean flow and bunkers right vectors favoring storm motions of 20-30
kts), and despite relatively low PWs (particularly compared to=20
warm season convection) any supercells will likely be capable of=20
1-2"/hr rainfall rates (per 40-km neighborhood HREF probabilities=20
for 1"/1-hr exceedance of 40-50%). While 1-2" totals should be well
tolerated by soils (and largely beneficial, given dry antecedent=20
conditions), localized training could result in too much rainfall=20
(2"+) too quickly (in a matter of 2-3 hours). Given this threat, an
isolated instance or two of flash flooding is possible.

Hurley/Churchill


Day 2
Valid 12Z Fri Oct 25 2024 - 12Z Sat Oct 26 2024

....2000 UTC Update...
The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Hurley


Day 3
Valid 12Z Sat Oct 26 2024 - 12Z Sun Oct 27 2024

....2000 UTC Update...
The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Hurley


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/94epoints.txt__;!!DZ3fjg!5BfqqOH3cxm5SKVvnTfTHguP4JHKnbquoz-HJGeEC1VD=
uZBPgCf4EHsRxnGdJ6lkL14fZufxBS8s2drU82OVlatvcYA$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/98epoints.txt__;!!DZ3fjg!5BfqqOH3cxm5SKVvnTfTHguP4JHKnbquoz-HJGeEC1VD=
uZBPgCf4EHsRxnGdJ6lkL14fZufxBS8s2drU82OVwVe0FzY$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go=
v/qpf/99epoints.txt__;!!DZ3fjg!5BfqqOH3cxm5SKVvnTfTHguP4JHKnbquoz-HJGeEC1VD=
uZBPgCf4EHsRxnGdJ6lkL14fZufxBS8s2drU82OVqWEItgw$=20

=3D =3D =3D
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