Mesoscale Precipitation Discussion 0348
NWS Weather Prediction Center College Park MD
1225 AM EDT Tue Jun 03 2025

Areas affected...eastern NE into western IA

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

Valid 030424Z - 030840Z

Summary...Areas of flash flooding will remain possible over the
central Plains, especially over portions of eastern NE during the
next couple of hours. Between roughly 07-08Z, the potential for
flash flooding will begin to shift into western IA, though
rainfall rates may be lowering by that point in time.

Discussion...The merging of a line of thunderstorms moving south
along a cold front and an eastward/northeastward advancing outflow
boundary from western KS into southern NE resulted in a burst of
very cold cloud tops over NE between 02-03Z, with 10.3 micron
imagery from GOES East showing cloud tops near -80 C, and MRMS
hourly rainfall of 2 to 3+ inches. Cloud tops have warmed a bit
since then but strong to severe thunderstorms remained with
locally heavy rain continuing over south-central NE. To the south,
surface dewpoints ahead of the outflow were in the upper 60s to
lower 70s over east-central KS and this low level moisture was
surging northward toward southeastern NE in advance of the outflow.

The well-defined cold front to the north will continue to advance
southeastward over the next few hours, eventually meeting with the
increasing low level moisture across the Missouri River Valley.
The advection of low level moisture into the region will result in
increasing instability, with recent RAP forecasts indicating
1000-2000 J/kg MLCAPE into southeastern NE over the next couple of
hours, along with decreasing convective inhibition.

The main concern for additional flash flooding will come from a
convectively induced vortex located northwest of GRI at 04Z, as it
follows ENE through eastern NE and eventually reaches western IA.
Rainfall rates of 1-2 in/hr are expected, although locally higher
values will be possible, along with an additional 2 to 3 inches of
rain on a localized basis.

Otto

ATTN...WFO...DMX...FSD...GID...LBF...OAX...

ATTN...RFC...KRF...MSR...NWC...

LAT...LON   43329482 42589467 41719526 40879628 40549783
            40719906 40580032 40800050 41380035 41759974
            42499769 43159641