Mesoscale Precipitation Discussion 0558
NWS Weather Prediction Center College Park MD
616 PM EDT Sun Jul 29 2018

Areas affected...eastern CO into western KS

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

Valid 292215Z - 300415Z

SUMMARY...Heavy rain on top of wet soil conditions may pose a few
areas of flash flooding through 04Z over portions of eastern CO
into western KS. Rainfall rates near 2 in/hr will be possible
despite an expected forward propagation to thunderstorms.

DISCUSSION...Local radar at 2130Z showed 2 or 3 strong storms in
close proximity over the eastern CO/WY border, with an average
movement toward the southeast between 25 and 35 kt. Two recent
wunderground.com sites to the northeast of Cheyenne recorded
roughly 2 inches of rain in about 30 minutes ending at 21Z with
similar rain rates observed across the High Plains in recent days
with similar thermodynamic profiles.

Large portions of eastern CO into western KS and southwestern NE
have seen over 300% of normal rainfall over the past week leading
to near saturated soils and lower flash flood guidance of 1-2
in/hr and 1.5 to 2.5 inches in 3 hours across most of the central
High Plains.

Current instability estimates per the 21Z SPC mesoanalysis page
shows a minimum in MLCAPE over western KS with higher values
(~2000 J/kg) over southeastern CO. While some degree of CIN is
present over eastern CO given stable wave clouds seen with current
visible satellite imagery, increased forcing for ascent is
expected after 00Z ahead of an advancing shortwave currently over
the northern High Plains. Upper level diffluence ie expected to
increase along with increasing easterly upslope flow near/north of
the southern CO/KS border between 00-03Z which may aid in
additional storms ahead of what is expected to be a forward
propagating cluster of convection over northern portions of the
MPD threat area. Cell mergers and boundary collisions may support
short term rainfall rates near 2 inches on top of near saturated
soils which is expected to drive a flash flood threat into the
overnight.

Otto

ATTN...WFO...BOU...DDC...GID...GLD...LBF...PUB...

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

LAT...LON   40700251 40450151 40010043 39309927 37909913
            37120012 37160217 37550351 38570436 39620458
            40620429