Mesoscale Precipitation Discussion 0956
NWS Weather Prediction Center College Park MD
343 PM EDT Tue Oct 09 2018

Areas affected...Northeast Kansas, Northwest Missouri, Southern
Iowa

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

Valid 091941Z - 100030Z

Summary...Thunderstorms and heavy rain bands were beginning to
expand in coverage from eastern Kansas, into northwest Missouri
and southern Iowa early this afternoon. As areas of heavy rain
become more widespread, the risk of flash flooding should
increase. Chances of flash flooding would be highest from the
Kansas City Metro Area northeast along the I-35 corridor, an area
that has received several inches of rain in the past couple days
already.

Discussion...Regional radars show a squall line becoming
increasingly well-defined, arcing across far southeast Kansas as
of 1930Z, and pushing rapidly off to the NNE or NE (depending on
the exact portion of the line). GOES-16 IR channels also showed
cooling cloud tops, and there were some CG lightning strikes
showing up in NLDN in the past hour or two. All these signs are
indicative of a strengthening band of convection in a region of
mid-upper level PVA. The low-level inflow area over Missouri
(southeasterly winds) was moderately unstable with RAP analysis
showing MLCAPE values reaching 1000 j/kg. The combination of this
increasing instability and precipitable water values around 1.6
inches should yield heavy rain rates in the strongest convection,
reaching 1-2 in/hr in narrow swaths where individual cell motions
prolong the heavy rain longest. Ahead of the squall line,
additional scattered convection was developing over northwest
Missouri and southern Iowa. This was likely due to increasing
low-level WAA and northward moisture flux associated with a strong
LLJ lifting north with the low-level cyclone over Kansas. This may
create some training patterns over parts of the outlined area,
with corridors of up to around 2 inches of rain. Flash flood
guidance was reduced across the region due to recent heavy
rainfall, particularly from far eastern Kansas, into the Kansas
City Metro Area, and up the I-35 corridor to near the IA-MO
border. In that specific area, 3-hr FFG is less than 1.5 inches,
certainly achievable given the atmospheric ingredients in place.
The negating factor could be the relatively fast storm motions.
Therefore, the flash flood threat will hinge on the ability for
convection to be channeled into training patterns for an hour or
two in a particular area, and/or the antecedent conditions being
especially favorable for additional flooding.

Lamers

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

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

LAT...LON   41829311 41229244 40199317 39359375 38149453
            37749531 38409587 40109565 41419469