textproduct: Des Moines

KEY MESSAGES

- Enhanced Risk (level 3 of 5) in eastern Iowa. All severe hazards, including large hail, damaging wind, and tornadoes, are possible with storms today.

- Much cooler this weekend with overnight lows in the 20s and 30s.

- Mild and dry to start the week with thunderstorms returning to the forecast by late week.

SHORT TERM /THROUGH TONIGHT/

Issued at 101 PM CDT Fri Apr 17 2026

The surface low early this afternoon is centered across north central Iowa with attendant sharp cold front pushing across the state. The impact was already being felt this morning in northwest Iowa when Estherville fell from 71 degrees at 10am to 43 degrees by 10:07am. Early convection has bubbled in northern Iowa and into Minnesota associated with lift in the vicinity of the surface low. The cold air sharply undercuts the warm and deeply unstable air in place with the primary trough farther to the west. This will allow for a period of some post-frontal elevated storm development, something already noted with elevated showers in northwest Iowa this morning behind the surface front. Across the state two primary ares of convective development are anticipated into the afternoon, noted in midday satellite imagery. The first is pre-frontal convection developing in an area of convergence noted in surface observations across eastern Iowa and visible in a plume of cumulus. A second line of cumulus trails along the cold front across western Iowa that will push across Iowa through the rest of the afternoon.

Much of the prefrontal convection is expected to develop east of the area, perhaps clipping far southeastern parts of the area near Ottumwa. There is plenty of available instability with 3000-4000 J/kg of MUCAPE (3000+ MLCAPE) and steep mid level lapse rates of 8+ C/km. Much of this instability is elevated with very little in the lowest 3 km (<100 J/kg). This will limit low level stretching and some of the tornado potential locally, though it is certainly NOT eliminated. The steep mid-level lapse rates, along with well curved hodographs in the low levels will help with rotating updrafts and hail growth. Storms are expected to quickly grow upscale. As this happens the initial discrete development will become multi-cell to linear as it pushes east, transitioning to a damaging with threat with tornado potential along the line.

LONG TERM /SATURDAY THROUGH THURSDAY/

Issued at 101 PM CDT Fri Apr 17 2026

Much colder air pushes in with the cold front as temperatures fall into the 30s tonight. Saturday remains breezy with continued cold air advection and the enhanced pressure gradient across the area. Temperatures in the upper 40s north to mid 50s south with 20-25 mph wind through the day. By Sunday winds relax with temperatures warming slightly into the 50s to low 60s. The thermal ridge builds next week, bringing 70s back to the area. Much of the week is dry with storm chances returning late in the week.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1236 PM CDT Fri Apr 17 2026

Breezy southerly winds are increasing across the area ahead of a strong cold front moving across the state today with gusts of 25-30 kts. The front will sweep through this afternoon, exiting east after 00z. Early storms have bubbled across northern Iowa this morning and may come near KMCW in the next hour or so, however recent trends indicate this should miss KMCW so have kept from that TAF at this time. The main line of storms will develop in east central Iowa. This may come near KDSM and KALO, however satellite shows initiation should be just east of those sites so have removed mentions from those sites. KOTM will see the bulk of thunderstorm activity this afternoon from around 19-20z through 00s.

DMX WATCHES/WARNINGS/ADVISORIES

None.