Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Aug 04 2025 01:15:56

AWUS01 KWNH 040114
FFGMPD
SDZ000-040600-

Mesoscale Precipitation Discussion 0862
NWS Weather Prediction Center College Park MD
913 PM EDT Sun Aug 03 2025

Areas affected...Central South Dakota...

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

Valid 040115Z - 040600Z

SUMMARY...Narrow axis of slow moving, potentially repeating
thunderstorms capable of 1.5"/hr rates and localized totals to 3".
 Localized flash flooding possible.

DISCUSSION...GOES-E WV suite denotes a very sharp elongated trof
across the Missouri River Valley with a few vorticity centers
dotted along it, including one over east-central SD.  Stronger
upstream jet energy is over-topping the ridge across the Central
Rockies placing weaker upper-level flow but also sufficient
divergence to support outflow for thunderstorm activity.  In the
lower levels, the wind field is generally convergent along a weak
surface frontal boundary between KMBG toward a weak surface low
between K9V9 and KICR.  While winds, there are pockets of stronger
moisture convergence to support/maintain convective development.=20
CIRA LPW/TPW shows core of locally enhanced moisture exists
through and just east of the Missouri River in SDAK with surface
Tds of mid-60s to upper-60s east of the front while core of
mid-level moisture streams in to reduce mid-level evaporation.
Total Pwats of 1.5" along and east of the instability axis along
the front will allow for moderately intense rainfall production.=20
MLCAPE of 2000-2500 J/kg will provide strong updraft and
isallobaric moisture influx to support 1.5-1.75"/hr rates.=20=20

The weaker overall low level convergence (5-10kts) will continue
to support a scattered to widely scattered nature to the
convective pattern, though a bit more increased concentration is
expected near the center of the 850mb low across south-central SD.
 Recent Visible imagery from GOES-E depicts this increase in
recent convective development, which may increase the potential
for cell mergers or repeating in the next few hours.  Deep layer
steering flow is generally parallel to the frontal zone with a
slight eastward deflection expected as the LLJ strengthens/veers.
As such, it is possible for a widely scattered incident of 3"
totals.   Given FFG values are generally 1.5"/hr and between
2-3"/3hrs a localized incident or two of flash flooding will be
considered possible through the early overnight period; however,
the risk will not exceed the Sand Hills area of northern-NEB and
hence why is not included in the MPD risk area (even though
environment is slightly more conducive for higher totals further
south).

Gallina

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!-IUBTAEDGhiACwNjNJPseUjTuTFIEnuVSE7kvE858sPdkuVbeuRXxJKkqWSihJehrfq6=
1QLX22DQZXqJoUHNTVScxM8$  for graphic product...

ATTN...WFO...ABR...FSD...UNR...

ATTN...RFC...KRF...NWC...

LAT...LON   45879943 45879899 45769862 45429837 44829827=20
            43909824 43669823 43209839 43019880 43019950=20
            43149996 43540020 44150025 45110010 45619988=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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