Mesoscale Precipitation Discussion 0724
NWS Weather Prediction Center College Park MD
351 AM EDT Thu Jul 17 2025

Areas affected...East-Central MO...Southern IL..Southwest IND...

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

Valid 170750Z - 171330Z

SUMMARY...Increasing WAA convection aligned for potential training
across recently saturated grounds pose, possible incident or two
of localized flash flooding.

DISCUSSION...GOES-E 10.3um EIR animation shows an expanding
cluster of thunderstorms downstream of weakening MCS along cloud
debris edge.  RAP analysis and WV suite suggest a convectively
induced MCV or mid-level vorticity center across north-central MO
resides within favorable divergence region of passing cyclonic jet
streak over Southern MN.  This divergence pocket is expanding
downstream into central and S IL.  Here a weak surface inflection
can be seen near KAAA as the northern stream cold front rapidly
advances across the Great Lakes but flattens to the mean flow
across N MO.  Additionally, RAP Theta-E gradient analysis shows a
gradient extending from east of KCOU to KFYG to KSAR to KMVN and
along/just north of the Ohio River into Southern IND.  South to
southwesterly surface flow, further increased by southwest to
southwesterly 15-20kts at 850mb is orthogonal to this boundary and
appears to be the ascension plane and deep moisture convergence
for elevated convection to develop near the St.Louis Metro and
northward, with a few Tcu noted downstream into S IL.

Deep layer steering flow from the west, is fairly parallel to the
ascent plane and would support training of any convection across S
IL into SW IND.  AHPS and NASA SPoRT LIS 0-40cm soil saturation
analysis shows ground conditions remain fairly saturated into the
80th-90th percentiles with an axis of lowered FFG to 1.5"/hr and
just barely over 2"/3hrs.   Saturated mid-level profiles with RH
over 70% and ample 16-18C Tds at 850mb support overall 2"+ TPW
between the synoptic front and the Theta-E gradient boundary. 
MUCAPE values of 2000 J/kg suggest strong updrafts and moisture
loading in the lowest levels will support 2-2.25"/hr rates.  So
with some training, localized 2-4" totals resulting in possible
incident(s) of flash flooding through the late overnight period.

Gallina

ATTN...WFO...ILX...IND...LMK...LSX...PAH...

ATTN...RFC...KRF...MSR...ORN...TIR...NWC...

LAT...LON   39948978 39798834 39458685 38858627 38318662
            38078732 38038854 38269023 38629140 39239184
            39669142 39899062