108
FXUS63 KDMX 111752
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1252 PM CDT Fri Jul 11 2025

 ...Updated for the 18z Aviation Discussion...

.KEY MESSAGES...

- Flood Watch for Flash Flooding between US Highways 34 and 20
  through 7AM CDT this morning. Widespread rainfall totals
  between 2 and 3 inches with locally higher amounts.

- Flood Watch for Flash Flooding for the remainder of the day
  Friday from the Waterloo through Corydon areas and points east
  for another round of heavy rainfall this afternoon and
  evening.

- Scattered Severe Thunderstorms this afternoon and evening
  across portions of central Iowa (risk level 3 out of 5).
  Damaging winds and a tornado or two are the primary threats in
  addition to heavy rain.

&&

.DISCUSSION...
Issued at 104 AM CDT Fri Jul 11 2025

A long lived MCS with damaging winds will continue to propagate
east across the I-80 corridor early this morning, sustained by
a low level jet and along a gradient of steep mid level lapse
rates and downdraft CAPE. In this wake of this leading MCS,
training convection along a stationary front sustained by the
low level jet with a precipitable water axis around 2.00 inches
will yield heavy rainfall and a flash flood threat between US
Highways 34 and 20. Rainfall totals between 2.00 and 3.00 inches
are likely for many locations, with locally higher amounts in
excess of 4.00 inches. A Flood Watch remains in effect for these
areas until 7 am CDT this morning.

For this afternoon and evening, another round of strong to
severe storms with heavy rainfall is expected. Issued a second
Flood Watch for the Waterloo through Corydon areas and points
east for another round of heavy rainfall with precipitable water
values remaining near 2.00 inches with training convection
likely along the slow moving frontal boundary. Additional rainfall
amounts of one and a half to three inches are possible for
these areas, supported by the HREF LPMM QPF, MPAS CAMS and RRFS.
This also aligns well with the WPC Slight Risk in the Excessive
Rainfall Outlook for today (level 2 out of 4).

Regarding the Severe Risk for today, SPC has much of south
central into eastern Iowa in a Slight Risk for severe
thunderstorms (level 2 out of 5), with a small part upgraded to
Enhanced Risk (level 3 out of 5). Plentiful moisture and
buoyancy with MLCAPE on the order of 2000-3000 j/kg with daytime
heating will be in place along and ahead of a slow moving
frontal boundary. Deep layer shear around 30-40kts augmented by
an approaching shortwave this afternoon will promote another
round of severe thunderstorms. Outflow boundaries from morning
convection will have to be sorted out for their mesoscale
impacts on the thermodynamic and kinematic setup. Still, initial
supercell structures are favored with a tornado or two possible
with large low level curvature in the forecast hodographs and
low cloud bases. As storms become more numerous in the late
afternoon and evening, upscale growth is expected with damaging
winds becoming the primary threat.

&&

.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1245 PM CDT Fri Jul 11 2025

Scattered thunderstorms are the main concern for today. Storms
are already ongoing, and additional development is expected this
afternoon. These storms could produce hail and wind. Did add a
mention of wind for KOTM, but KALO and KDSM will have to be
watched as well.
Storms will move east this evening, with light winds overnight
and some patchy fog/stratus possible. Expect MVFR/VFR conditions
on Saturday.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Flood Watch through late tonight for IAZ038-039-049-050-
059>062-072>075-084>086-095>097.

&&

$$

DISCUSSION...Jimenez
AVIATION...MPX