Mesoscale Precipitation Discussion 0625
NWS Weather Prediction Center College Park MD
1208 AM EDT Tue Jul 16 2024

Areas affected...much of central Illinois, west-central Indiana,
and surrounding areas

Concerning...Heavy rainfall...Flash flooding likely

Valid 160407Z - 161007Z

Summary...Robust redevelopment of convection upstream of an MCS
over Indiana/central Illinois will pose a flash flood risk over
the next 6 hours (through 10Z).

Discussion...An intense, well-organized convective complex has
spread an appreciable amount of rainfall across much of northern
and central Illinois so far today, with widespread 0.5-2 inch
rainfall amounts noted.  That convective complex has now spread
into Indiana, although a strong cold pool extends westward through
Springfield, IL, then northwestward through Quincy, IL. 
Meanwhile, strong southwesterly flow at 850mb continues to
maintain strongly unstable air into and above the cold pool,
resulting in renewed, robust convective development from Peoria
westward to near Burlington, IA.  This convective development was
oriented parallel to steering flow aloft, favoring training and
areas of 1-2 inch/hr rain rates on grounds that already received
copious rainfall from the lead MCS in Indiana.  This regime is
already prompting excessive runoff across parts of west-central
Illinois.

This overall regime is expected to remain in place through the
next 4-6 hours, with areas of 1-2 inch/hr rain rates continuing to
materialize across the discussion area where convective bands are
most persistent.  The dominant band over/west of Peoria should
persist for at least another couple hours and perhaps shift slowly
southward.  Another one or two convective bands may also
materialize given the favorable thermodynamic environment and
multiple sources for ascent.  3-5 inch totals through 10Z cannot
be completely ruled out.  These rates should readily exceed FFG
thresholds, which may be lower than the 1.5 inch/hr rain rates
given the recent rainfall and wet soils.  Flash flooding is likely
in this scenario.

Cook

ATTN...WFO...DVN...ILX...IND...IWX...LOT...LSX...

ATTN...RFC...MBRFC...NCRFC...OHRFC...NWC...

LAT...LON   41428969 41058750 40138634 39518611 38808745
            38579029 39659143 41289109