textproduct: Des Moines

KEY MESSAGES

- Showers are expected today into Saturday morning. A few storms remain possible in southeast Iowa early this afternoon but the window is quite small in space and time for any stronger storms (tornado potential), though an isolated storm wind gust is possible as are a few funnel clouds. Locally heavy rainfall is also possible, especially north and east, though the overall risk is lower with less rain overnight/this morning, but could still occur in mainly an urban area.

- Increasing winds with gusts of around 35 to 45 mph spread from northwest Iowa to eastern Iowa by around sunset.

- Relatively cooler and quiet weather is then forecast Saturday through at least Monday.

SHORT TERM /THROUGH SATURDAY/

Issued at 254 PM CDT Fri Jul 31 2026

Surface low has moved into northern Iowa early this afternoon with a cold front extending to the south of the low which eventually arcs back into the Southern Plains. Widespread cloud cover remains in place around the low with a few breaks showing up on satellite to the east of the cold front. The small area of a warm sector ahead of the front (generally east of I-35) is the main area to watch for any thunderstorm development this afternoon. Showers have been ongoing much of the day in the north, with more recent shower development further south through portions of central and even southern/southeast Iowa. Although dew points are in the 70s in portions of central and southern Iowa, temperatures are also still in the 70s to touching 80. With the scattered showers already incoming, our window for stronger storms is small in both space and time. The main favorable location is in southeast Iowa, east of I-35 and south of I-80 which is where the SPC Day 1 Marginal is roughly located. The challenge is 0-1 SRH quickly dwindles with time in the next few hours and where surface-based CAPE over 1000 J/kg exists, soundings do not support much in terms of a tornado threat, as discussed in the previous discussion. DCAPEs do reach towards, though still below, 1000 J/kg at times so an isolated strong to marginally severe gust cannot be ruled out with the drier air working into the storms from aloft, but the overall probabilities for severe storms remains low with higher probabilities to the east and south of our area. There may still be some potential for some funnel clouds as 0-3 CAPEs overlap with the surface vorticity, especially near the low, with the NAM/GFS/RAP all highlighting areas of mainly north central initially (around 19Z, as also noted in SPC Mesoanalysis data) and then east central to eastern Iowa with the non-supercell tornado parameter. These conditions will certainly be watched closely, especially with where cloud breaks are occurring.

Outside of the stronger storm potential just discussed, main weather for the next 12-18 hours will be the scattered showers and the increasing wind gusts. These gusty winds out of the north have started to enter northwest Iowa early this afternoon and are expected to move in northwest to southeast through the night. Peak gradient gusts top out around 35-45 mph, isolated higher, with breezy conditions remaining behind the strongest gusts into Saturday afternoon before winds diminish into Saturday night. These gusts may touch Wind Advisory criteria at times, but expectation was not widespread enough to issue a headline.

In terms of rainfall, heavy rain remains possible with pwats less than the were this morning, but still over 1", and warm cloud depths. Showers in northern Iowa are also expected to move slower than in southern Iowa and these slow moving showers with some backbuilding/training potential could lead to QPF adding up. With less rain into this morning, capacity remains higher for heavier rainfall amounts into this evening and any flooding concerns remain mainly in urban areas in far north to eastern Iowa. See the HYDROLOGY section below for more details.

Showers will be slow to depart into Saturday morning in the east/southeast, but dry conditions look to return by Saturday afternoon. Hazy skies may remain beyond clouds clearing west to east as wildfire smoke aloft looks to return to the state. Temperatures Saturday remain pleasant and in the 70s to low 80s.

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/

Issued at 254 PM CDT Fri Jul 31 2026

Pleasant and dry conditions continue on Sunday and Monday as the upper ridge builds eastward with temperatures in the upper 70s to low 80s. Active weather then returns through mid next week as a longwave trough approaches with several waves moving through the overarching upper level flow. This will return precipitation chances to our area from Tuesday night to around Thursday with the pattern looking to remain active into next weekend. Temperatures don't really rebound keeping conditions for early August largely nice and in the 80s.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1248 PM CDT Fri Jul 31 2026

VFR to LIFR conditions ongoing across the state early this afternoon. Although some improvement towards low VFR may occur at times, prevailing MVFR to IFR will be more common with clouds and additional developing showers, few storms this afternoon through evening. The storm potential remains highest east of I-35 but confidence in TSRA actually impacting KALO or KOTM was not high enough to move out of prob30 group. Have otherwise tried to update timing and used tempo/prob 30s for visibility reductions with showers though some additional refinement to impacts or timing is likely with scattered nature of activity outside of KMCW which may see more steady rain for a time. Although some sites are reporting fog, as winds increase fog should continue to be less of a concern. North winds continue to increase northwest to southeast this afternoon into evening and stay breezy into Saturday. Peak gusts may near 30-40 knots. Ceilings begin to improve Saturday morning into midday northwest to southeast.

HYDROLOGY

Issued at 1144 AM CDT Fri Jul 31 2026

Rainfall for this event has generally underachieved vs. earlier forecasts thus far, thus hydrologic responses on area rivers and streams has been less than anticipated. The Cedar basin from southeast MN into northeast IA received the heaviest rainfall, and the Cedar River itself is expected to crest around action stage early next week in the Waterloo-Cedar Falls area. The upper-most portions of the Des Moines basin in southwest MN received some locally heavy rainfall which may lead to minor rises downstream into northwest IA next week, but is expected to remain below action stage.

Additional moderate to locally heavy rain is expected this afternoon and evening, mainly across the eastern third of IA. Greatest flood risk is ponding or possible low-end flash flooding mainly in towns and cities, mainly east of US 63, which would be primarily within the Cedar-Iowa basin. Going Cedar River forecasts for the Waterloo- Cedar Falls area incorporate the most likely QPF scenario through 12Z Saturday.

DMX WATCHES/WARNINGS/ADVISORIES

None.