textproduct: Des Moines

KEY MESSAGES

- Several rounds of storms are expected today into Thursday. All severe hazards will be possible through this period including damaging wind gusts, large hail, tornadoes, and heavy rain. There is a threat for storms overnight tonight into Thursday morning in addition to storms that develop in the afternoon and evening. Have a shelter plan in place and a way to be woken up if sleeping should a warning be issued for your area tonight. - Brief break in storm chances Friday with more storms, some severe, returning on Saturday.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 340 AM CDT Wed Jun 10 2026

Storm activity over the Dakotas has grown upscale as expected with a MCS moving northeastward through Minnesota. Portions of this line did briefly move through portions of the northwest early overnight with some wind gusts to around 30-40 mph noted in northwest Iowa to adjacent southwest Minnesota with much stronger gusts further west in that line affecting parts of the eastern Dakotas into western MN. A few additional storms moving out of eastern NE did reach our far west central counties before dissipating as well.

We now have a short break for a few hours but attention turns to the west with activity developing over central Nebraska with additional early day development expected in western Iowa on the nose of the strong 40-50+ knot LLJ and ahead of the approaching upper trough and associated surface low. Warm air aloft remains in place keeping any early day activity here elevated. Shear early this morning remains weak, less than 30 knots, but mesoanalysis reveals 3000-4000 J/kg of MUCAPE and DCAPEs of 1100-1200 J/kg. Although some of this instability will wane with time into the daybreak hours, some strong to locally severe storms are certainly possible with strong wind gusts the primary threat, though some hail could be possible. Largely expecting bulk of early day activity today to be non-severe in our area though this development is expected to grow upscale with time becoming the first threat of the day to the east in eastern IA, WI, and IL. Will certainly monitor closely for any strong to severe storms that can get going in this first round this morning.

Clearing is expected behind this early day activity with new storm development in the mid to late afternoon. Ample moisture advection returns MUCAPE values back to 3000-4000 J/kg by midday though this highly unstable environment is dependent on the expected atmosphere recovery. A cold front is expected to be moving into northwest Iowa by around midday today, with a warm front closer to the Great Lakes making the warm sector between right over much of the area. Gradient winds will be gusty, around 20-25 mph sustained and gusts to 35 mph so it won't take much for higher gusts to be achieved. Bulk shear finally catches up by mid afternoon, anywhere from around 30-45 knots thus leading to organized convection that would support all modes of severe weather from damaging winds, large hail, and tornadoes. 06Z data has increased the afternoon SRH to around 100- 200 m2/s2 further westward than previous runs. Initial development is modeled to be over the south and east though some additional storms may be able to develop further north into early evening as the jet enhances again. Any supercells that can develop would have the best chance for a tornado and the largest hail which in our area is the far east or southeast though could potentially arc back into parts of central Iowa pending atmosphere recovery and location of the convergent boundary storms develop on.

The afternoon/evening is not our only threat of storms today into Thursday morning. The surface low lifts out of KS, through Iowa, and into the Great Lakes from early Thursday into Thursday afternoon. The upper level trough also finally moves through on Thursday afternoon. Another strong 40-50 knot jet will aide in storm development to the northeast of this surface low with very strong theta-e advection. Shear will be very strong, around 50-60 knots in southwest Iowa with a still deeply unstable environment for the time of day (overnight). There is an uneasy amount of consistency amongst models of a cluster of storms, including with supercell structures developing in southwest Iowa early (3-4 AM) and lifting north and east with time. These would pose a risk for all hazards again, tornadoes, large hail, damaging winds, and with time, this too looks to grow upscale into a MCS with an increasing wind threat into the daybreak hours as it crosses Iowa. SPC Day 2's outlook notes the potential for some strong tornadoes, and winds becoming potentially destructive. These storms would all be developing during a time of night when most folks are sleeping so it is important to have a way to be woken up should a warning be issued for your area overnight tonight.

Any trailing outflow or the approaching cold front could then reactivate on Thursday afternoon and evening providing yet another chance for severe weather. It is possible that if we have widespread storms in the morning that activity develops further south and east later Thursday afternoon/evening with just trailing rain instead.

The storms, especially the overnight activity tonight, could bring several inches of rain to areas that have received heavy rain in the last several days. Guidance is suggesting more widespread 1-2" with localized areas of 2-4"+ See the hydro section below for a bit more details on the hydro threat.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 313 PM CDT Tue Jun 9 2026

A brief reprise from the storms develops Friday but precipitation chances then return again into the middle of the weekend. Severe storms are once again possible on Saturday in southern Iowa. See the SPC Day 4 Outlook for additional details. Cooler temperatures then follow on Sunday into early next week with temperatures back in the 70s.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 644 AM CDT Wed Jun 10 2026

Surface S to SSW wind will increase this morning and be breezy to gusty at times. Isolated SHRA/TSRA are expected across the NW two- thirds of IA early in the TAF period, however confidence was high enough for PROB30 only at KDSM and KALO. Scattered SHRA/TSRA also possible this afternoon into early evening across SE half of IA, mainly along and southeast of a KALO to KDSM line including KOTM. Maintained PROB30 at those three terminals. Sfc wind will diminish and become more SSW to SW this evening. Additional TSRA possible late in the TAF period with KDSM at highest risk of impacts, so introduced PROB30 there.

HYDROLOGY

Issued at 313 PM CDT Tue Jun 9 2026

Short and longer term hydrologic conditions exist due to active weather over the next few days. Main short term concern is flash flooding potential. Despite widespread amounts of 2-3 inches over the past five days across the southeast half of the CWA with pockets of 4-5+ inches, much of the rain ran off instead of infiltrating because of its intensities/rates. Thus it did not significantly change soil moisture vs. how much rain fell. Compared to normal soil moisture for this time of year, the northwest CWA is the driest, the south central into northeast CWA is slightly above and most other areas are near normal. Although areas with above normal soil moisture are traditionally most susceptible for flash flooding, nearly the entire CWA has the same risk for this event because rainfall intensity/rates over the next few days will likely exceed soil infiltration capabilities in many locations including drier soils, practically speaking. The most likely scenario will be ponding and lower-end flash flooding mainly in towns and cities, however higher than expected rainfall would increase the geographic and magnitude risk.

Longer term, the risk of river flooding over the next several days is minimal (generally less than 15-25%), however minor to moderate within-bank rises are again possible in basins that receive heavier rainfall.

DMX WATCHES/WARNINGS/ADVISORIES

None.