textproduct: Des Moines

KEY MESSAGES

- Showers will expand across the state through this afternoon into the evening, continuing overnight into Thursday. Widespread 1-2+" of rain expected across Iowa by Thursday evening.

- Strong to severe thunderstorms are possible in Iowa Thursday afternoon, mainly over southern and eastern Iowa. All severe hazards are possible.

- Additional severe storms on Friday. An Enhanced Risk (Level 3 of 5) is in place for central and southern Iowa. All severe hazards are possible.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 240 PM CDT Wed Apr 1 2026

Relatively benign conditions are noted across Central Iowa so far today, with most areas seeing mostly cloudy skies as a shortwave passes overhead. Temperatures have warmed into the 40s across the state, which may warm a few degrees yet in some spots but will otherwise remain on the cooler side for the rest of today. Patchy and light returns are seen on radar this afternoon, though conditions per surface observations have remained dry. Could see periods of relatively light rain as these patchy weak showers lift northeast through the remainder of the afternoon. Surface cyclogenesis on the lee side of the Rockies is expected to occur this evening, developing the system that will ultimately drive the active forecast through Thursday with this low pressure moving across the Midwest. In the meantime though, showers ahead of this system are still expected to expand in coverage northeastward across Iowa into this evening. Latest CAM guidance continues to show this scattered shower activity well north of the surface warm front, which into late this evening is oriented west to east over northern Missouri. Given this location of the surface feature, and the bulk of better forcing from the increasing low level jet concentrated over Missouri, the overall potential for storm coverage into southern Iowa looks fairly low. A closer look at soundings shows deep lift associated with a strong low level jet and saturation through the column as moisture surges northward, bringing PWAT values around 1.25-1.5 into the state. Rainfall therefore will be quite efficient and widespread, with periods of heavy rain as this activity lifts north across the state through the morning, with the potential for areas of ponding and even some minor flooding, especially in low-lying areas. Please see the specific hydrology section further below for additional details. In terms of storm potential into Iowa, cannot rule out a few elevated weak storms into southern Iowa tonight into Thursday as a notable inversion sets up, paired with rather limited instability overhead. Shower and storms are expected to continue through Thursday morning, with this boundary expected to lift into far southern Iowa around or just after sunrise, with much of the activity expected to remain generally over central to northern Iowa through the remainder of the morning, with embedded non-severe storms possible.

As the surface low continues to deepen as it quickly pivots northeastward across Iowa in the morning, this initial round of showers/storms will decrease in coverage by late morning as the warm front quickly moves northeastward, allowing for a period of some drying to occur for much of the area. Warm and moist air is progged to lift into the state into the afternoon as well, especially over southern and eastern Iowa where highs are expected to top out into the 60s to low 70s. While there are some minor variations in guidance, the general trends show a cold front arriving over the western portion of the forecast area, as the system tracks directly over central Iowa, with this front surging eastward across the state through the afternoon before departing east out of the area by the early evening. Additional showers and storms are expected to develop ahead of this boundary roughly after 12-1pm, with relative fast storm motions as they race northeastward through about 5-6pm. A dive into the mesoscale environment during the afternoon shows increasing instability values around 1000+ J/kg, along with bulk shear values around 35+ knots. The indication of dry air in the low levels and steep lapse rates would point to hail and damaging winds for threats over southern and eastern Iowa, though a few tornadoes cannot be ruled out where curving hodographs are noted. A Slight Risk area per SPC now extends into parts of east central to eastern Iowa. Some uncertainty is in play regarding the extent of severe storms development, since lingering cloud cover from the morning convection could limit clearing potential that would be ideal for supercell potential, so something to watch through the day. Regardless of whether strong/severe storms develop, increasing synoptic winds over southern and eastern Iowa will occur ahead of the cold front, with gusts expected to push 35-40+ mph at times, though should diminishing through the evening.

Northwest winds are expected to push through the state Thursday evening, which will bring cooler air overhead into Friday. Overnight low are expected through the 30s to mid 40s, warmest south.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 240 PM CDT Wed Apr 1 2026

The pattern remains quite active to end the work week, as another trough moves across the western CONUS and lee side cyclogenesis occurs off the Rockies once again, producing an even more potent low pressure system that is forecast to track eastward into the Central Plains. This surface low in relation to the previous system is a bit further south in comparison, but is expected to sharply pivot up through Iowa by the late afternoon to evening. While dry conditions are expected at least through the morning, warm and moist air quickly lifts into Iowa through the afternoon, especially southward of I-80, with forecast highs expected to top out into the upper 40s to 50s over roughly the northern half of the state, and in the 60s to low 70s over the southern half. The main focus area however will come late afternoon to evening as a rather strong cold front arrives into western Iowa, tracking eastward across the state. The environmental parameter space over the warm sector looks to be quite conducive for potential severe weather, with very unstable conditions given values of 2000+ J/kg of CAPE, bulk shear values of 40-45+ knots, and SRH values over 300 m2/s2, with all modes of severe weather possible. The Enhanced Risk area per SPC remains south of I-80 given the more favorable setup. Details regarding overall expectations will become more clear over the next few days.

The dry slot arrives into Saturday following the departing cold front, with northwest spreading across Iowa through the day that will lead to notably cooler temperatures and breezy conditions. Guidance indicates wrap around precipitation on the cold side of the deepening low as it continues to northeastward, though trends keep most if not all of this activity generally along and north of the IA/MN border. Certainly something to watch as a southern trend could mean the introduction of at least some wintery mix to extend into northern Iowa.

A building ridge into early next week suggest generally quieter conditions over Iowa, with mainly quiet weather and northwest flow.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1241 PM CDT Wed Apr 1 2026

Expect aviation conditions to deteriorate from south to north this afternoon into tonight. Current MVFR/IFR ceilings in far southern Iowa will push nwd, impacting OTM/DSM from 21z-00z, and northern terminals between 03z-06z. In addition, rain showers will increase in coverage and intensity this evening into tonight with MVFR, to occasional IFR VSBYs. While instability will be modest overnight, embedded thunderstorms are possible at OTM/DSM, and maintained the PROB30 to account for this threat. Winds during this period will remain easterly /15-30kts/.

A second round of thunderstorms is possible towards the end of the TAF period, after 15z, some of these storms could become strong to severe. More details in future updates.

HYDROLOGY

Issued at 130 PM CDT Wed Apr 1 2026

Continued short and long term flooding considerations exist due to the imminent multi-day seasonally moderate to heavy rainfall event, mainly across the southeast half of the CWA.

Short term considerations include potential ponding and low-end flash flooding. Soil moisture values are generally running near to below normal. That data combined with the QPF suggests any ponding and flash flooding will be mainly rate vs. amount driven, with the greatest risk in urban areas.

Longer term considerations include potential river flooding. GFS- and NBM-forced National Water Model, HEFS and QPF ensemble hydrographs indicate the most likely scenario will be moderate to significant within-bank rises. A few locations may reach flood stage, however minor flooding would be expected at most if it occurs. The peaks on most rivers will occur this weekend into early next week. Greater concern is the next few days of rainfall may set the stage for more significant impacts going forward if the wet pattern continues.

DMX WATCHES/WARNINGS/ADVISORIES

None.