FXUS63 KDMX 220344
AFDDMX

Area Forecast Discussion
National Weather Service Des Moines IA
1044 PM CDT Fri Aug 21 2026

 ...Updated for the 06z Aviation Discussion...

.KEY MESSAGES...

- Marginal (Level 1 of 5) Risk for severe weather across 
  southern Iowa. Damaging winds and large hail are the primary 
  threats.

- Fairly consistent highs through midweek next week, ranging 
  from the 70s to low 80s across Iowa.

- Dry through the weekend, precipitation chances return Sunday
  night into Monday and at times next week.

&&

.SHORT TERM /THROUGH TONIGHT/...
Issued at 230 PM CDT Fri Aug 21 2026

A cold front is currently making its way across Iowa this afternoon 
and evening. In front of it, a field of diurnal cumulus has formed. 
There are low expectations with this cumulus field as far as 
precipitation chances go today. As far as the environment across 
Iowa goes, MLCAPE values are in the neighborhood 2500J/kg across 
central and eastern Iowa with little in the way of CIN. Shear in 
northwest Iowa is decent - around 30 kts - and guidance suggests 
weak forcing is available in the northwestern portion of the area. 
That said, dry air has been pushing its way into the state through 
the day and there is very little in the way of moisture return which 
limits the potential for convection. Similarly, across southern Iowa 
which has been outlined by a Marginal (Level 1 of 5) Risk for severe 
weather today, CAPE (around 2500J/kg) and shear (35-40kts) would 
indicate some amount of severe weather potential, but with dry air 
pushing in and very little in the way of forcing, the threat for 
severe weather looks highly conditional. Should the boundary provide 
enough forcing for an updraft to organize, there's still potential 
for it to produce large hail and damaging winds.

Otherwise, overnight precipitation chances diminish even further as 
the aforementioned dry air continues to be advected in from the 
north. This dry air is being advected by a high pressure system, 
which will sink into the area on Saturday. This high pressure 
indicates fair weather and clear skies for the weekend. Continued 
northwesterly flow means temperatures will remain just below normal. 
Keeping with this trend, skies will remain clear Saturday night and 
through part of Sunday before moisture builds back into western 
Iowa.

&&

.LONG TERM /SATURDAY THROUGH FRIDAY/...
Issued at 230 PM CDT Fri Aug 21 2026

Iowa remains seated between a ridge centered over the Four Corners 
region and a trough over the Great Lakes. If either of these systems 
shift, that will change how far east or west moisture gets back into 
the area by Sunday night, which is when the next shortwave looks to 
move through, potentially bringing more precipitation chances into 
Sunday morning. At the moment, however, deterministic guidance is 
still struggling with the timing of this system. With this comes 
some degree of disagreement with placement, all of which will be 
better assessed in the coming days. This upper level pattern looks 
to remain rather stagnant, with the potential for additional 
shortwaves to move through the region next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 1039 PM CDT Fri Aug 21 2026

Skies are clear for the most part across the state except for some 
lingering smoke aloft. This may continue into tomorrow but is not 
expected to be impactful. Some patchy fog development remains 
possible tonight, particularly at KOTM, but given the extra breeze 
behind the front and dry air advection, seems unlikely at this 
point. Cumulus may develop at KDSM/KOTM terminals tomorrow but will 
likely stay VFR.

&&

.DMX WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

SHORT TERM...67
LONG TERM...67
AVIATION...De Bruin