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000
AWUS01 KWNH 160324
FFGMPD
SDZ000-160730-

Mesoscale Precipitation Discussion 0156...Corrected
NWS Weather Prediction Center College Park MD
1123 PM EDT Mon Apr 15 2024

Corrected for Resent for spelling errors

Areas affected...Western to South-central South Dakota...

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

Valid 160250Z - 160730Z

SUMMARY...Very high moisture flux over outflow boundary is
resulting in efficient rainfall production and with slow forward
propagation may pose higher rainfall totals (2-3") capable of
inducing localized incident(s) of flash flooding.

DISCUSSION...Rapid surface cyclogenesis is occurring just south of
the Black Hills of SD where a 989mb low was noted.  Very strong
isallobaric wind response is generating very high southeasterly
and easterly confluent low level flow across the central Plains
into SDak.  Upon this, moisture has been channeled into a tongue
across northeast NEB angled into western NEB.  Given surface winds
of 30-35kts and 850mb flow and winds at the boundary layer of
50-60kts, moisture flux has been very strong.  Initial rounds of
thunderstorms generated cold pools from drier mid-level air in
place subsequently resulting in favorably oriented outflow
boundaries to the flow to support additional rapid convective
development along the isentropic ascent.

Combined with natural low level barrier in the Black Hills low
level winds remain highly convergent resulting in sufficient
moisture flux into the developing storms for fairly efficient
rainfall production (updraft loading) given the overall drier
environment. While UDX RADAR suggests modest hail generation, KDP
field also supports downdrafts with fairly decent rainfall
generation while supporting 1.5-2"/hr estimates.  Forward
propagation should be effective in eastward cell motions, but
current trends suggest stronger mid to upper level divergence
channel toward the northwest and north is supporting downshear
updraft columns maintaining a bit longer duration for heavier
rainfall to accumulate before the outflow boundary presses too far
east and generates another updraft cycle further west.  As such,
north/south oriented lines of enhanced rainfall should be expected
over the next few hours with slow eastward advancement before
approaching shortwave from the southeast triggers a stronger
complex further upstream robbing the best environmental moisture
flux.  As such a few lines of 2-3" totals are possible over the
next 3-4hrs slowly advancing eastward into central SDak.

While the soils have been dry, the shear magnitude of rainfall and
naturally lower FFG values north of the Sand Hills, suggest these
2-3" totals in 1-3hrs may induce a localized flash flooding
incident or two through 08z and considered possible.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

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

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

LAT...LON   45210237 45080119 44099989 43499991 43290028
            43370099 43720166 43600249 43340304 43470358
            44050378 44830337