881
FXUS63 KDMX 051202
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
702 AM CDT Wed Aug 5 2026

 ...Updated for the 12z Aviation Discussion...

.KEY MESSAGES...

- Locally heavy rainfall with isolated flash flooding risk over southern
  Iowa today. Rounds of rain and storms over southern into
  portions of central Iowa this morning drifting southeastward
  through the day. Much of the rainfall is over for southern
  Iowa by this evening.

- Below average temperatures the rest of the work week, followed
  by warming temperatures and storm chances.

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 226 AM CDT Wed Aug 5 2026

Convection has blossomed early this morning on the cool side of the
surface front that is near I-70. While the axis of the broad trough
is over the eastern Dakotas into eastern Nebraska with shortwave
energy aiding in this increase in convection, it is more so the
forcing from the 850mb low level jet pointed into southwestern Iowa
that has increased its coverage. The main concern with these storms
will be locally heavy rainfall. Latest mesoanalysis shows good
moisture transport with up to 1.8 inches of precipitable water
values being advected into the region with the 850-300mb winds from
the southwest around 30 knots, which is fairly well aligned with the
orientation of the surface and elevated boundary. Already this
morning have noted repeat rainfall rounds (aka training storms)
along the US 34 corridor over southwestern Iowa with several
clusters. However, versus one congealed area there is spacing
between the cells lessening the immediate risk of flash flooding.
Further, there has been some degree of cold pool push from the
storms such that they are deviating slightly to the southeast from
the east to west storms, though also note additional development
back over the Omaha metro that could fill in yet this morning.
Recent runs of the HRRR and RRFS are keying in on these areas with
localized rainfall amounts of 4 to 5 inches with the WPC QPF showing
3 to 4 inches. For the higher end potential, the 0z REFS and HREF
show localized probability matched mean bullseyes at or over 6".
While there was rainfall over southern Iowa Tuesday evening with a
few pockets in Davis County around 2 inches, most areas were under
an inch. Thus, antecedent conditions remain overall dry with flash
flood guidance values still being seasonally high along with mature
crops that will readily absorb the moisture. While any urban center
is more prone to flash flooding if high rates and repeat rounds
occur, have issued a flood watch for a few counties in our
southeastern forecast area that had the rainfall Tuesday evening and
are a bit more primed.

Now, these areas won`t be the only places that see rain early this
morning with scattered storms moving northeastward from southwestern
Iowa into portions of central and our north central and northeastern
forecast area to around Mason City and the Waterloo area. As for the
severe risk over southern Iowa, there were some gusty winds in
southwestern Iowa shortly after midnight with personal weather
stations reporting wind gusts between 45 and 55 mph. Given the
saturated profiles, think these gusty winds will be quite limited
and hail potential as well given the deep warm layer.

Showers and storms will continue at times this morning, especially
over southern into portions of central Iowa, as they slowly sink
southeastward. Additional rainfall of 1 to 2 inches is possible over
southern Iowa. Much of the rainfall will have ended north of I-80 by
early afternoon with southern Iowa drying out by late this afternoon
or this evening. Thus, confidence continues to increase that the
higher rainfall totals tonight will be over Missouri.&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 251 PM CDT Tue Aug 4 2026

In the extended, temperatures will stay near to below average
through the end of the work week and 90 degree highs will try to
make a return over the weekend. The region will be locked in
northwest flow which keeps thunderstorm chances in play.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 702 AM CDT Wed Aug 5 2026

Showers and storms are passing through central and southern Iowa
this morning, leading to MVFR and IFR conditions at KOTM and
KDSM. Flight restrictions could continue into the afternoon
hours with the highest confidence at KOTM. Areas of light,
patchy fog have started to develop at KFOD and KMCW behind the
line of showers; however we are not expecting any restrictions
this morning at these terminals. As we near the end of the TAF
period, areas of fog could develop over eastern Iowa. MVFR
restrictions have been introduced to highlight the fog, but
lower flight categories may be required as confidence builds in
later TAF issuances.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
Flood Watch through this evening for IAZ086-096-097.

&&

$$

SHORT TERM...Ansorge
LONG TERM...Jimenez
AVIATION...TDR