854
AWUS01 KWNH 080135
FFGMPD
IAZ000-080600-

Mesoscale Precipitation Discussion 0587
NWS Weather Prediction Center College Park MD
935 PM EDT Sun Jul 07 2024

Areas affected...Central Iowa

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

Valid 080134Z - 080600Z

SUMMARY...Flash flooding possible as storms move across portions
of Iowa with saturated soils. Rates to 2.5 inches per hour
possible.

DISCUSSION...A potent positively tilted shortwave in the
subtropical jet has provided the forcing for scattered showers and
thunderstorms to develop over portions of western Iowa this
evening. While decently fast-moving, the storms are moving over
much of Iowa that has been hard-hit with heavy rainfall over the
past couple weeks. Thus, FFGs across the central part of the state
are low enough that while conditions for heavy rainfall are
somewhat less than ideal, cell mergers and outflow boundary
collisions are locally slowing the motion of the storms as they
follow the enhanced forcings. Thus, expect with continued
development of the storms east across Iowa, additional instances
of flash flooding are possible.

PWATs across Iowa are around 1.3 to 1.4 inches with MUCAPE values
around 2,000 J/kg. These values will support additional storm
development over the next few hours.

CAMs guidance suggests the storms forming now over the
northwestern part of the state will gradually coalesce into a
small MCS, which will then weaken as it gets to the eastern part
of the state in a few hours due to rapidly decreasing instability
along the Mississippi River where ongoing rainfall is itself
weakening for the same reason. HREF guidance shows about a 30%
chance of exceeding FFGs across portions of the area for both 3
and 6 hour FFGs.

Wegman

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ARX...DMX...DVN...

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

LAT...LON   43489301 43459282 42679163 41369227 41169347
            41199471 41859507 42539488 43179433 43459369