Mesoscale Precipitation Discussion 0242
NWS Weather Prediction Center College Park MD
122 PM EDT Thu May 08 2025

Areas affected...portions of the Lower Ohio Valley and Tennessee

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

Valid 081722Z - 082322Z

Summary...Slow-moving showers and thunderstorms are producing
spots of 1-1.5 inch/hr rain rates at times across southern
Illinois.  These rates should continue, with storms translating
slowly eastward toward central Kentucky and Middle Tennessee
through 23Z/6p CDT.

Discussion...A combination of factors was contributing to a
focused area of convective development across western areas of the
discussion area (from southern IL through northwestern TN) over
the past couple hours: 1) insolation/surface destabilization
occurring beneath a slow-moving mid/upper low over Missouri and 2)
convergence along a synoptic front extending from near SAR
east/northeast to ILN.  Mid-level flow fields are relatively weak,
resulting in slow-moving and weakly organized convection that has
exhibited multiple cell mergers at times.  Moisture/instability
profiles are supporting areas of 1-1.5 inch rain rates beneath the
most persistent convection and merging cells, which was resulting
in areas of FFG exceedance especially where heavier rates have
persisted for more than an hour.

Models/obs suggest that the area of convection will gradually
translate eastward mainly across Kentucky and Tennessee over the
next 6 hours or so.  Occasional cell mergers/spots of FFG
exceedance are expected on an isolated basis.  The combination of
both propagation and newer downstream development of convective
activity suggests that a modest increase in flash flood potential
should occur from western Kentucky eastward through the I-65
corridor, with central KY/middle TN risk peaking from 19Z onward.

Cook

ATTN...WFO...ILN...ILX...IND...JKL...LMK...LSX...MEG...OHX...
PAH...

ATTN...RFC...LMRFC...NCRFC...OHRFC...NWC...

LAT...LON   39278510 36568497 35828675 35698910 36469000
            37109006 37798970 38798762