Mesoscale Precipitation Discussion 0771
NWS Weather Prediction Center College Park MD
756 AM EDT Mon Jul 21 2025

Areas affected...eastern Kansas, northwest Missouri

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

Valid 211155Z - 211700Z

Summary...Showers and thunderstorms will continue for a few more
hours this morning. Rainfall rates of 1-2"/hr are expected, which
through backbuilding/repeating could cause 2-3" of rain with
locally higher amounts. This may result in additional flash
flooding before convection wanes late this morning.

Discussion...The regional radar mosaic this morning shows an MCS
draped NW to SE across north-central Missouri. Recent evolution of
this MCS clearly indicates an outflow boundary (OFB) beginning to
push away from the deepest convection, and this OFB is tracking
slowly westward. At the same time, regional VWPs indicate the
850mb winds have continued to veer to become more westerly at
25-30 kts, becoming orthogonal to this OFB to support increased
convergence and isentropic ascent within the continued warm
advection. The result of this has been to transport elevated
thermodynamics eastward, characterized by PWs around 2 inches and
MUCAPE over 2000 J/kg, to support additional convective
development with radar-estimated rain rates of 1-1.5"/hr.

The CAMs are generally struggling with the current activity, so
confidence in the evolution the next few hours is modest. However,
the recent RRFS and to some extent 3kmNAM appear to reflect best
the conceptual evolution within the evolving mesoscale pattern. As
the OFB continues to track WSW, and low-level flow remains out of
the west, a shortwave over NW Kansas will track eastward.
Together, these will persist sufficient ascent to offset the
general weakening of the thermodynamic advection anticipated in
the next few hours. The result of this will be continued
thunderstorm development from eastern Kansas into northwest
Missouri, potentially including the Kansas City metro area. Rain
rates of 1-2"/hr are expected at times, and although the general
intensity is expected to wane in the next few hours, slow motion
and backbuilding of cells (progged via Corfidi vectors collapsing
to 5 kts or less) could result in 2-3" of additional rainfall with
locally higher amounts possible.

7-day rainfall across this area has been well above normal,
reaching as high as 300-400% of normal according to AHPS, and this
has lowered FFG to 1.5-2"/3hrs. Some areas at risk this morning
have also experienced impressive overnight rainfall to
additionally prime the soils, although the greatest potential for
more heavy rain appears to be west of these areas. Still, both
HREF and REFS 3-hr FFG exceedance probabilities exceed 10-20% in
the next few hours. This indicates at least a continued isolated
flash flooding risk this morning, with the greatest potential
occurring where any backbuilding convection can train across more
vulnerable soils or urban areas.


Weiss

ATTN...WFO...DMX...EAX...ICT...LSX...OAX...SGF...TOP...

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

LAT...LON   40699444 40529359 39789291 39269246 38759191
            38409191 38189236 37929330 37919370 38229625
            38459709 38809733 39369703 40149597