Mesoscale Precipitation Discussion 0927
NWS Weather Prediction Center College Park MD
121 AM EDT Sat Oct 06 2018

Areas affected...South-Central to Eastern IA...Northern
IL..Southern WI

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

Valid 060520Z - 061120Z

Summary...Repeating showers and thunderstorms overnight will
maintain the threat for flash flooding.

Discussion...The latest radar imagery shows an expansive axis of
heavy showers and thunderstorms extending from northwest MO and
south-central IA northeastward across northern IL and into far
southern WI. The convection is focusing within a strong warm
advection pattern along and north of a well-defined frontal zone
as a wave of low pressure attempts to lift northeast along it.

The activity has been almost entirely elevated in nature and is
being aided by a robust 40 to 45 kt southwest low level jet which
is helping to transport anomalous moisture up along and over the
front in conjunction with moderate instability. In fact, much of
the convection is aligned within an axis of MUCAPE values ranging
from 1500 to 2000 j/kg. Additionally, the convection is being
aided by large scale ascent associated with right-entrance region
upper-level jet dynamics.

The latest hires model consensus, including recent runs of the
HRRR, suggests a continuation of an elongated and broken axis of
showers and thunderstorms focusing north of the front. The
convection has already been repeating over the same area across
portions of eastern IA and northern IL in particular, and this
concern will continue through the night. Additional rainfall
amounts of as much as 2 to 3 inches can be expected going through
dawn, and with wet antecedent conditions, the threat for some
flash flooding will continue overnight.

Orrison

ATTN...WFO...ARX...DMX...DVN...EAX...LOT...MKX...

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

LAT...LON   43038924 42988782 42368722 41778760 41438907
            41059090 40759215 40619294 40549385 40639408
            40869427 41209392 41709257 42639079