textproduct: Des Moines

KEY MESSAGES

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

- Highs across central Iowa climb into the lower to mid 80s.

- Mostly dry and sunny through the weekend!

SHORT TERM /THROUGH TONIGHT/

Issued at 202 AM CDT Fri Aug 21 2026

Mostly dry conditions will prevail across central Iowa on Friday. A slow moving cold front currently positioned across southeastern South Dakota will continue pushing southeastward throughout the day. While pre-frontal convection remains possible along the boundary in Minnesota, activity is expected to dissipate as it moves into central Iowa and encounters a more stable air mass. A stray shower or storm will still however be possible during the early morning hours in northern Iowa.

By Friday afternoon, diurnally-driven destabilization ahead of the boundary will build MLCAPE to 2000-3000 J/KG. Combined with 35-45 kts of 0-6km bulk shear, the environment will be conditionally favorable for organized severe convection. However, convective initiation confidence remains low due to two primary limiting factors: high pressure to the north advecting mid-level dry air and a weak thermal gradient across the front resulting in broad- weak low- level convergence. Despite these inhibition factors, the Storm Prediction Center has issued a Marginal Risk (Level 1 of 5) across southern Iowa. If an isolated parcel manages to break the cap, robust updrafts could produce damaging wind gusts and large hail. The highest precipitation chances (10-20%) will align with late afternoon into evening (generally after 6pm). Post frontal high pressure will build in overnight, clearing skies from north to south.

Elevated haze will persist today as northwesterly flow aloft advects upper level wildfire smoke from the Pacific Northwest. This smoke layer will remain elevated aloft, with no surface air quality impacts anticipated.

Friday Night

Northwesterly flow will reinforce a dry, subsidence airmass across the region, setting up quiet conditions overnight through Saturday morning. The next window for organized precipitation arrives Sunday evening.

LONG TERM /SATURDAY THROUGH THURSDAY/

Issued at 222 PM CDT Thu Aug 20 2026 Another embedded shortwave will move across Iowa late Sunday evening into Monday, slowing from model solutions 24 hours ago. The upcoming work week looks to remain active with embedded shortwaves continuing to ride along the western US ridge with northwest flow across Iowa. A more robust system looks to move across the area on Tuesday and will be the next opportunity for more organized convection. At this time range differences remain with the GFS favoring a southerly track over the Euro northerly track.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1209 PM CDT Fri Aug 21 2026

Mostly VFR conditions are expected at all terminals this TAF period. MVFR cumulus clouds have formed ahead of a weak front that is pushing through the state which will impact KALO, KDSM, and KOTM. Coverage of the cumulus is expected to be low so terminals are kept VFR through sunset when the cumulus will dissipate. Otherwise, light wind shifts are expected with mostly north to northwesterly winds through the period, with winds expected to stay around or below 10kts.

DMX WATCHES/WARNINGS/ADVISORIES

None.