Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Aug 18 2024 10:15:57

AWUS01 KWNH 181015
FFGMPD
NEZ000-SDZ000-181510-

Mesoscale Precipitation Discussion 0896
NWS Weather Prediction Center College Park MD
615 AM EDT Sun Aug 18 2024

Areas affected...portions of South Dakota

Concerning...Heavy rainfall...Flash flooding possible

Valid 181010Z - 181510Z

Summary...Isolated flash flood potential exists with a band of
convection across southern/central South Dakota this morning.=20
Areas of 1-1.5 inch/hr rain rates are occurring and should
continue through 14Z or so.

Discussion...Over the past 1-2 hours, a nearly stationary band of
convection has materialized on the nose of a strong (35 kt) 850mb
jet.  The cells were also embedded in northwesterly flow aloft
that was oriented parallel to this axis of convergence.=20
Additionally, cells were on the eastern edge of a steep lapse rate
plume, with impressive 8-9C/km 700-500mb lapse rates noted per
objective analyses.  The orientation an intensity of the
convection has fostered a relatively slow-moving axis of 1-1.5
inch/hr rain rates to develop from just northwest of Pierre to
just southeast of Burke (near the SD/NE state line).

Models/observations suggest that this band of convection will move
slowly with time.  Convection should persist for a few hours,
although eventually 850mb convergence will weaken some due to
backing and weakening flow at that level.  In the meantime, spots
of 1-2 inch/hr rain rates will occasionally exceed FFG thresholds
in that area (generally in the 1-2 inch/hr range - lowest with
northwestward extent).  Flash flooding is possible in this regime.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!89ZSt5BsHxwrk6OB-eE7fA2UKDLSotg8A4crKAtUjUL-cHGGcq2ukY2WX07N_BpCtl1G=
_HJb9IQi8fvRcNuhIEw_RC0$  for graphic product...

ATTN...WFO...ABR...FSD...LBF...OAX...UNR...

ATTN...RFC...MBRFC...NWC...

LAT...LON   44990130 44920008 44369821 43339734 42779751=20
            42819938 43790110=20

=3D =3D =3D
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