Mesoscale Precipitation Discussion 0180
NWS Weather Prediction Center College Park MD
853 PM EDT Fri Apr 26 2024

Areas affected...portions of Iowa

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

Valid 270053Z - 270453Z

Summary...Localized areas of training convection continue to
support 1+ inch/hr rain rates at times.  Flash flood potential
continues on an isolated basis through 05-06Z.

Discussion...Robust convection continues to develop within a
relatively focused axis of instability across southwest and
west-central Iowa (characterized by 1000+ J/kg SBCAPE).  Cells are
focused in a couple of areas - 1) located from southwest of Fort
Dodge through the Harlan, IA area and 2) southwest of Des Moines
near Creston.  Storms in these areas were developing, moving
quickly northeastward and even outpacing northeastward movement of
the surface-based instability axis, but then backbuilding within
the axis due to strong ascent and cold air aloft approaching the
region.  The backbuilding has resulted in a few spots of 1.5+
in/hr rain rates, which were threatening FFGs in a few spots and
posing a risk of excessive runoff and flash flooding.

Models/observations suggest that the ongoing scenario (supporting
isolated flash flood potential) should continue for a few more
hours.  Most high-resolution guidance clears the region of
convection after 05-06Z, which seems plausible as the mid-level
wave forcing ascent for convection (currently centered over
Nebraska) shifts northeastward and geopotential heights begin to
rise in its wake.  Again, a few areas of flash flood potential
should arise on occasion through that timeframe.

Cook

ATTN...WFO...ARX...DMX...DVN...EAX...FSD...OAX...

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

LAT...LON   43389428 43089305 41779232 40839243 40509402
            40699499 42339569 43099523