textproduct: Des Moines

KEY MESSAGES

- Severe storms are possible across central Iowa late this afternoon through this evening. Although gusty winds will be the primary threat, hail, and a tornado will be possible as well

- Flood Watch is in effect through Saturday morning as saturated ground from recent heavy rain combines with the likelihood for additional heavy rain from more storms

- More storms, although more isolated will be possible again on Saturday afternoon and night

SHORT TERM /THROUGH SUNDAY/

Issued at 153 PM CDT Fri Aug 14 2026

The main focus this afternoon and evening will be on an MCV and associated shortwave trough currently moving through eastern Nebraska. It arrives into western portions of the CWA by mid- afternoon, encountering a destabilizing air mass, which will eventually provide access to a reservoir of anomalously high moisture values, if realized. In fact precipitable water values in excess of 2" push it into the 99% of normal for this time of year, which when combined with saturated soils from recent heavy rains be justification for the continuation of the Flash Flood Watch (more on that in the hydrology section below). Enhanced mid-level flow associated with the MCV will add to the already adequate 30+ knot of deep layer shear in place across the region. Favorable timing of the MCV passage during peak heating where surface-based CAPE values are progd to approach and/or exceed 2000 j/kg all point to increasing severe weather potential across central Iowa. As for hazards, damaging wind gusts in this very HP environment will be the primary, followed by hail along with a tornado or two. Earlier runs of the HRRR identified a UH track very in the vicinity of I-80 later this afternoon and evening, which is plausible based on the hodograph and adequate SRH values, should the instability be tapped. SPC boosted TOR potential with the latest SWODY1 to 5% as a result. The one potential fly in the ointment is the cloud-cover. Should cloud-cover inhibit the anticipated daytime heating, the severe weather threat would be reduced. Keep in mind too, CAMs have been struggling both in time and space with the recent run of high moisture days. Storms should push east of the CWA 03-06z, giving way to improving conditions overnight, which will be a welcome change from the daily onslaught of overnight severe weather.

Another shortwave trough will move through the region on Saturday afternoon and night bringing the next round of shower and thunderstorm chances. In general short range models have trended towards less coverage during this period, but still with the anomalously high PWATs remaining place, did not want to adjust pops dramatically from the NBM. What will feel different tomorrow will be temperature, with high climbing into the low 80s north and mid/upper 80s south.

LONG TERM /SUNDAY THROUGH THURSDAY/

Issued at 153 PM CDT Fri Aug 14 2026

At this point, Sunday looks drier as a drier air mass advects in as evident by PWATs dropping to near 1" across central and north. Looking into next week periodic shower and thunderstorm chances will continue to be possible, however, it appears that these will be more seasonal, compared to the past week.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1236 PM CDT Fri Aug 14 2026

Anomalously high moisture content for this time of year is yielding widespread cloud-cover for area terminals, including fairly widespread IFR CIGS. Morning thunderstorms have ended, but new showers are developing ahead of a weather system that is set to track through this afternoon and evening. Expect that trend to continue through early afternoon, with an area of more robust thunderstorm development, initial thinking is west of DSM tracking east between Interstate 80 and Highway 30 through 03z. Have trended TAFs accordingly. Afternoon thunderstorm trends will need to be closely monitored, as adjustments in timing and location will no doubt be necessary. Storms depart 03-06z, although expect poor aviation conditions to persist through the morning, before improving after sunrise.

HYDROLOGY

Issued at 153 PM CDT Fri Aug 14 2026

Cumulative impacts from multiple rounds of moderate to heavy rain over the past couple days, followed by more rain later today and tonight, will likely lead to at least significant ponding especially in urban areas, as well as possible river and/or flash flooding elsewhere.

WPC Day 1 excessive rainfall outlook (ERO) continues moderate risk across much of central and southern IA. The combination of current soil moisture levels and QPF suggest the area of most concern for flash flooding extends approximately from US Hwy 30 on the north to IA Hwy 92 on the south, with a secondary area extending from the Boone to Fort Dodge area. This area includes the Ames and Des Moines metros, as well as smaller streams in those areas like Ioway Creek (Ames) and Walnut and Fourmile Creeks (Des Moines).

Moderate to significant within-bank rises are still expected on many streams. At least isolated minor river flooding is also possible. Just a little more QPF than forecast may produce more significant flooding however. For example, if QPF averages around 0.5 to 1 inch more than forecast, then widespread minor river flooding with multiple locations seeing moderate or possibly major flooding may occur.

Some river forecasts bring levels close to flood stage, and we would normally issue river flood watches for those locations. However, we decided to let the going areal flood watch for much of our CWA cover the river flood potential due to spatial overlap, and to minimize potential confusion associated with some areas having two flood watches. If the river flood threat continues after the areal flood watch expires or is canceled, then we may issue river flood watches for the potentially affected locations.

DMX WATCHES/WARNINGS/ADVISORIES

Flood Watch through Saturday morning for IAZ023>028-033>039- 044>050-057>062-070>075-081>086-092>097.