Mesoscale Precipitation Discussion 0738
NWS Weather Prediction Center College Park MD
325 PM EDT Thu Aug 30 2018

Areas affected...southwest MO, southeast KS, northern AR,
northeast OK

Concerning...Heavy rainfall...Flash flooding likely

Valid 301925Z - 302325Z

Summary...Additional flash flooding appears likely across portions
of southeastern KS into southwestern MO/northeastern OK and
northern AR. Additional 2-4 inch totals are expected through 23Z.

Discussion...Radar and infrared satellite imagery showed a
weakening convective complex with warming cloud tops moving along
the western MO/AR border, but a second cluster on its heels along
the southern KS/MO border with cooling cloud tops. The second
(strengthening) cluster appeared to be elevated, rooted somewhere
between 850 and 700 mb, with unidirectional westerly flow near and
above 700 mb promoting training. Despite portions of southeast
KS/southwest MO having been impacted by earlier heavy rain over
the past 6 hours, the 18Z SPC mesoanalysis depicted a reservoir of
large instability (2000-3000+ J/kg MLCAPE) present over
northeastern OK into central AR to the south of a stationary
front, likely feeding in from the south to help sustain rainfall
rates of 1-2 in/hr in what would otherwise be a worked over
atmosphere. Trends in radar suggest this area will track over some
of the same regions of southwest MO that were impacted by earlier
heavy rain, increasing the threat for additional flash flooding
over the next few hours. Therefore flash flooding appears likely
in the short term, but a turn toward the right into higher
instability is possible toward 00Z.

Flow across the region remains fairly diffluent in the 500-300 mb
layer, which should help to support vertical lift through the
column but it is unclear how long heavy rainfall will continue
across western portions of the MPD threat area given placement
behind a departing low-mid level shortwave located over southwest
MO as of 19Z. Moderate to strong CAPE over central AR and weak
mean storm motions of 1-10 kt may promote a localized flash flood
threat farther to the south across portions of north-central AR
given the weak low-mid level flow. Hi-Res models have struggled to
handle convective development across this region so far today
which lowers confidence a bit compared to average heading through
the remainder of the afternoon.

Otto/Weiss

ATTN...WFO...ICT...LZK...MEG...PAH...SGF...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...

LAT...LON   37839512 37749373 36939215 36709137 36349059
            35599073 35139182 35039258 35189366 35719512
            36879578 37809524