textproduct: Des Moines

KEY MESSAGES

- Precipitation today will be mainly west of Interstate 35 with chances increasing again later today and into tonight.

- More widespread storms overnight. A few strong to severe storms possible over mainly southern Iowa. While localized heavy rain over 3 inches may occur, this does not appear to be widespread.

- Severe weather remains possible on Monday though some uncertainty remains with the tornado potential due to timing and potential residual cold pool from overnight convection.

SHORT TERM /THROUGH MONDAY/

Issued at 403 AM CDT Sun Apr 26 2026

The majority of the significant weather for this 7 day forecast is mostly confined within the next 36-40 hrs. A few light showers have reached the western forecast area as the initial wave of modest theta-e advection and moisture transport arrive. The activity is a bit more vigorous over southeast Nebraska and moving into far southwest Iowa where some lightning is occurring.

A robust PV anomaly/short wave cluster is now located near southern Nevada and moving east/northeast. Surface lee side cyclogenesis will intensify over southeast Colorado through the day and would enhance the southerly flow into Iowa later today and tonight as the low moves east into southwest Kansas. This should keep most of the precipitation today confined to western Iowa until stronger moisture transport arrives later tonight as the low level jet (LLJ) increases. The primary LLJ focus should be along and just north of a warm front extending across central Missouri while the mid-level moisture transport will extend farther north into southern Iowa. PWAT values will increase to 1.25"-1.5" which are seasonally high and warm cloud depths across southern Iowa will be around 9 kft. With the majority of the thunderstorms activity arriving after midnight when the mean layer wind increases a fair amount leading to faster storm motions, the very heavy rain potential will be reliant on prolonged training/repeating of storms. All of this along with current antecedent conditions, not very confident in the potential for river flooding or flash flooding potential across the area. Will continue to monitor in case the LLJ focus shifts north and places the stronger forcing and moisture support into southern Iowa. A few strong to severe storms are possible later tonight as increasing MUCAPEs and mid-level lapse rates arrive. A few storms with large hail and damaging wind gusts may occur along with an elevated supercell potential as the layer speed shear increases and supports organized development.

The main focus is on the severe weather potential as the western PV anomaly/short wave lifts into Nebraska and southeast South Dakota while the surface low lifts across Iowa. A few items of note. As the upper level energy approaches, the static stability from the boundary layer to the tropopause will become low and less than 10k. This means that it won't take much forcing to move air parcels vertically and this could result in widespread thunderstorm development if the Elevated Mixed Layer doesn't sufficiently materialize. The more widespread activity may also lead to storms ingesting cool inflow from nearby competing storms. Will need to see how much recovery can occur from the departing early morning storms and the surface based activity that may develop by late morning. Should recovery occur, then tornado potential will increase with storms that can maintain a favorable inflow as the streamwise vorticity ingestion still looks favorable in the 0.15-0.2 range and good low level turning. Hodographs due become more cyclonic in the mid-levels and given mostly unidirection speed shear aloft, elevated left moving supercells producing large hail may also occur. Stay tuned as this remains a fluid situation.

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/

Issued at 403 AM CDT Sun Apr 26 2026

Little sensible weather is expected for much of the extended as several iterations of high pressure will move through the region. Troughing will dig into the Upper Midwest Wednesday and Wednesday night and will be followed by a short wave arriving late Thursday and Thursday night. This could bring the next chance for precipitation to the state but chances remain low enough at this time to keep PoPs to a minimum. Temperatures much of the period will be seasonal with highs in the 50s and 60s through the work week and lows in the 30s and 40s. Perhaps a few chances for frost at times, mainly north. The coldest low temperatures are currently projected for Thursday night but that is also coincident with the potential system arriving that night that could involve more wind and/or cloud cover which would limit frost.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 702 AM CDT Sun Apr 26 2026

Showers will wane over central Iowa over the next couple hours, but the main wave of showers and storms begins late afternoon. Highest confidence for TSRA will be in the late night, but some chances for storms exist in the evening as well and PROB30s may need to be adjusted in future issuances. Included gusts for all terminals, but chances for stronger gusts exists with storm outflow. CIGs will lower through the night, likely reaching IFR towards the end of the period.

DMX WATCHES/WARNINGS/ADVISORIES

None.