textproduct: Des Moines

KEY MESSAGES

- Scattered showers and thunderstorms Thursday afternoon ahead of a severe line expected to pass across the state late Thursday afternoon and evening. Damaging wind is the primary hazard, however large hail and tornadoes are possible (primarily with initial storm development west).

- Cooler Friday through the weekend with showers and thunderstorms possible Saturday and Sunday.

SHORT TERM /THROUGH THURSDAY/

Issued at 133 PM CDT Wed Apr 22 2026

A cluster of thunderstorms in northwest Iowa early this morning fizzled out as it move across north central Iowa through midday. Conditions cleared out quickly behind. Southerly flow with theta e advection into the area persisted the rest of the day ahead of an approaching surface low across western Montana this afternoon. Drier air is in place west with deep mixing this afternoon, resulting in wind gusts of 20-25+ mph through the afternoon north and west. Winds begin to come down after sunset as the nighttime inversion sets up, however it is not super deep and winds are not expected to completely drop off overnight.

Deep moisture transport increases across the area on Thursday as the surface low approaches the area. Scattered showers and thunderstorms will increase across the area by early afternoon with this increased moisture and boar ascent ahead of the boundary. The surface cold front then sweeps across the area from west (around 21z) to central (00-02z) and exiting east (04-05z). Better forcing along the frontal boundary will allow for more robust convection and will hold the severe potential for the day. Expect initial discrete storm developing along the boundary in western Iowa to quickly grow upscale into a linear complex. A plume of 1000-1500 J/kg MLCAPE will be in place along with shear around 40 kts. It is important to note that the shear is largely parallel to the line and should mitigate much of the tornado potential along the line of convection. Initially discrete cells in west/southwest Iowa may have a brief window with higher tornado potential, especially given curved low level hodographs. The Creston sounding indicates around 200 m2/s2 0-1km SRH around 21-23z. There is also question as to how surface based these storms will be, and therefore able to take advantage of the low level helicity. With several hours of sub- severe showers and thunderstorms ahead of the main line soundings are fairly saturated in the low levels as the main forcing mechanism comes through and enhances convection.

LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/

Issued at 133 PM CDT Wed Apr 22 2026

Cooler air behind the cold front leaves highs Friday in the 60s and these will hang around through the weekend and much of next week. A deep trough will remained parked across Alberta and Saskatchewan with embedded wave rounding the base and moving across the midwest through the weekend. The first is fairly weak and will bring a chance for rain on Saturday. Then, a more robust embedded wave will eject east and move across Iowa Sunday into Monday. A plume of instability with this wave lifts through the plains, but at this time does not quite make it to Iowa late Sunday. Adjustments to the track could result in adjustments to local severe impacts and will monitor closely as the event nears.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 649 PM CDT Wed Apr 22 2026

Over the next few hours, there is high confidence in VFR conditions prevailing at all terminals. Gusty winds from the south will prevail through much of the period and low level wind shear (LLWS) may develop tonight, but due to its expected sporadic and marginal nature have not included in terminals. Toward mid to late evening, it is uncertain whether stratus clouds over Missouri will prevail and make it to DSM so have SCT/BKN FL040-050 ceilings there. After midnight, expect more widespread MVFR ceilings to arrive from the west and spread across all but OTM through the period. There will also be a 5 to 8 hour period of IFR conditions at DSM, MCW, and FOD. Spotty showers may be possible in the morning as indicated by PROB30 groups before more scattered showers and storms develop mid to late afternoon.

DMX WATCHES/WARNINGS/ADVISORIES

None.