textproduct: Des Moines

KEY MESSAGES

- Morning storms today may pose a large hail threat south. Monitoring the potential for a wake low developing on the backside of these storms and gusty wind potential. Locally heavy rainfall still possible but hydrologic impacts are expected to be minimal.

- Afternoon surface based storms remain possible but the areal coverage for tornado potential is shrinking and confined to the southeast. It is possible this area becomes even more confined pending impacts from the morning convection.

- Only a few periods with precipitation chances this week. Seasonal temperatures are expected.

SHORT TERM /THROUGH TONIGHT/

Issued at 119 AM CDT Mon Apr 27 2026

The day for the well advertised system and severe weather potential has arrived. As previously mentioned, the forecast would remain fluid and the potential impacts of previous convection are already being seen as the developing low pressure and attendant warm front are a bit farther south than expected 24 hrs ago. That low pressure system is moving east across the Oklahoma panhandle with the warm front extending to the east. Recall the expectation was for this system to be across southwest Kansas. This will result in a farther east trajectory with the entire system as it lifts northeast later today.

Currently the low level jet (LLJ) is focus north into northeast Kansas where convection is initiating and lifting north. Monitoring the trends with that convection currently, there is a well defined supercell east of Selina, KS that is moving east and the convection east of that system is beginning to curl back to the west. This region of storms may very well consolidate and continue an eastward trajectory. Meanwhile, the convection over far northeast Kansas should move northeast into Iowa as the LLJ and the associated theta- e advection lift northeast into Kansas. A few severe storms with large hail will be possible especially late tonight into early this morning as mid-level lapse rates steeped sufficiently for greater vertical acceleration potential for rising parcels. CAM solutions are suggesting the potential for a mesolow to develop on the backside the backside of the complex as drier mid level air arrives and begins to erode the back edge. This could turn into gusty easterly winds which in a worse case scenario, could top 58 mph so will be alert for that potential. Locally heavy rainfall remains possible this morning though expect the heaviest rain to occur south of Iowa with the aforementioned area translating east out of Kansas. Not expecting much hydrology wise except for significant ponding potential should 2+ inches or rainfall occur.

The surface based convection potential for late this morning and into the afternoon remains conditional across the warning area. As mentioned above, the surface low will be lifting northeast later today but will be farther east, limiting the area of concern. In addition, the western PV anomaly and attendant short waves that are now crossing the Colorado Rockies, seems more fragmented with one fragment taking a more southerly route. Still have the main fragment and short wave trough lifting over Nebraska and southeast South Dakota, the other fragment is moving over Kansas and into northern Missouri this afternoon. That southern fragment along with this mornings convection may further influence a more southerly shift for the primary severe weather potential and further limiting the area of concern over central Iowa. There still remains potential for recover over south central into southeast Iowa and there appears to be a window for tornadoes though there is a trend in the CAMs that the surface based convection occurs while the low level shear becomes displaced to the east. The more southern track along with a remnant cold pool from this mornings storms could also push the afternoon severe potential mostly out of the area. Storms should be east of the county warning area by late this afternoon.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 119 AM CDT Mon Apr 27 2026

The primary challenges beyond today are a couple short waves expected to arrive late Tuesday/Tuesday night and another by late Thursday/Thursday night. Currently only have minimal mention for precipitation chances due to moisture challenges for each period. For Tuesday, any showers will be based AOA 8kft with a dry layer beneath the cloud bases. The Thursday system will be through northwest flow and relying on residual moisture attendant with the system but it does appear to have a more saturated profile. Temperatures will be seasonal through the week with highs in the 50s and 60s followed by some warming by next weekend. Overnight lows in the 30s and 40s could lead to a few periods with frost but again, the coldest temperatures are currently Thu night when the aforementioned system is expected to move through which would promote clouds and a bit more wind.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1108 PM CDT Sun Apr 26 2026

The initial round of showers and weak storms have largely moved out of Iowa, with a brief dry period expected across the terminals until after 07-08z, when the next round of showers and thunderstorms spreads from southwest to northeast over the forecast area. Overall trends continue to indicate highest potential for storms over southern Iowa, decreasing further north and east in probabilities, though exact timing of storms is still more uncertain. Therefore remaining with usage of PROB30 groups for storm mentions, with likely amendments based on how trends set up through the next several hours. MVFR/IFR conditions are expected through the morning as low ceilings spread across the state with this activity. A final round is expected to occur mainly over eastern Iowa as a cold front passes through into Monday afternoon. Otherwise, winds out of the southeast will be breezy with gusts up to 20-30 knots, shifting southerly and then westerly by late in the period following the frontal passage.

DMX WATCHES/WARNINGS/ADVISORIES

None.