Mesoscale Precipitation Discussion 0925
NWS Weather Prediction Center College Park MD
649 PM EDT Thu Oct 04 2018

Areas affected...south-central MO into western IL

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

Valid 042245Z - 050445Z

Summary...Repeating and training thunderstorms are expected to
produce localized rainfall totals of 2-3 inches through 05Z from
portions of MO into western IL, along with possible flash
flooding.

Discussion...KSGF reflectivity at 2230Z showed scattered
thunderstorms over south-central MO on either side of I-44. This
activity was elevated with mean movement off toward the northeast
at 15-20 kt, occurring north of a well defined quasi-stationary
surface boundary draped east to west across southern MO with low
level flow just above the surface of 20-25 kt intersecting the
front (via the KSGF VAD wind plot). The thunderstorms appeared to
be developing in part due to the brushing influence of the
southern edge of a 700 mb shortwave identified in area VAD wind
plots and RAP analyses moving northeastward across MO. MUCAPE to
the north of the quasi-stationary front was weak via the 21Z SPC
mesoanalysis (500-1000 J/kg) but trending upward in magnitude in
south-central MO as increased low level moisture advects into the
region.

Some further increase in MUCAPE is expected to occur in MO/IL as
the shortwave passes by to the north and flow around a large
subtropical ridge over the Southeast continues to funnel in low
level moisture through at least 06Z. As this occurs, thunderstorm
coverage is expected to increase with 850-700 mb flow of similar
direction but stronger magnitude compared to the 850-300 mb flow.
This should allow for training and repeating of cells from
south-central MO into western IL with an overall movement off
toward the northeast. These storms will be located within a ribbon
of narrow but higher total precipitable water values which could
support rain rates up to 1.5 in/hr. Given pockets of lower Flash
Flood Guidance across the region, localized flash flooding will be
possible given the coverage of 1+ in/hr rain rates should remain
minimal.

Otto

ATTN...WFO...EAX...ILX...LSX...SGF...

ATTN...RFC...LMRFC...MBRFC...NCRFC...

LAT...LON   40239010 40138891 39148874 38178977 37129140
            36869251 37339334 38329320 39729164