textproduct: Des Moines

KEY MESSAGES

- Widespread showers and thunderstorms (60-100% chance) continue today, mainly in southern Iowa. The primary threat is heavy rainfall and possible flooding, mainly near the IA-MO state line. There is also a very low risk of severe weather there.

- Slightly below average temperatures are forecast for most of next week with highs in the 70s to lower 80s.

- There will be several chances for showers/thunderstorms, with a Marginal Risk being introduced for Tuesday.

SHORT TERM /THROUGH MONDAY/

Issued at 248 AM CDT Sun Jun 21 2026

Thunderstorm activity remained south of Iowa overnight, instead the southern half of the state was occupied by steady rain. We still have a shot at thunderstorms later this morning and it's dependent on activity in central Nebraska. That being said, lightning and cloud temperatures have not impressed thus far and 00z CAMs are too strong compared to reality. Still, once the nose of the LLJ gets into southern Iowa around sunrise, the CAPE axis will come near, as will the higher PWATs near 2". Peak rainfall amounts will occur before noon in southern Iowa, rain more to the north with taper to a drizzle by midday. Rainfall amounts over 2" are most likely within the Flood Watch in the far south, but most of the area will see amounts near the 1" mark.

CAPE values for today have also trended lower; less than 500 J/kg. So the Marginal Risk is largely out of the state, save for the far southeast. Highs have trended lower. Most of the area will be in the mid to upper 60s.

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/

Issued at 128 PM CDT Sat Jun 20 2026

After the precipitation event ends Sunday night, the synoptic pattern next week will feature a predominately northwest upper flow regime, due to ridging out west, and a mean trough over the far northern CONUS. The latest 12Z model guidance indicates that several shortwaves will propagate through the mean flow, but as per usual, the timing and amplitudes of individual shortwaves is more uncertain attm. There is reasonable confidence that Tuesday night and early Wednesday, and Friday have the highest potential for more organized precipitation. Due to the NW flow regime, limited low level moisture return is expected, thus instability profiles appear mostly meager. As such the threat for severe weather next week appears low attm. However, it is June, and with stronger wind profiles and colder temperatures aloft, we'll need to watch for any sneaky severe threats. Finally temperatures next week look to stay below late June averages, with highs generally in the mid-upper 70s, maybe a few 80 by late week, we'll take that all things considered.

AVIATION /12Z TAFS THROUGH 12Z MONDAY/

Issued at 641 AM CDT Sun Jun 21 2026

Rain hasn't moved as far north as previously anticipated, so have delayed arrival in northern sites and have delayed the arrival of MVFR/IFR. Have also removed TSRA from all but KOTM as lightning hasn't materialized overnight. MVFR and IFR cigs will be likely today with rain. There remains uncertainty on the northern extent of rain, so left MCW as Prob30. Rain will gradually exit the area after 18z, ushering in VFR conditions lagged by and hour or two.

HYDROLOGY

Issued at 128 PM CDT Sat Jun 20 2026

See the main portion of the discussion for the meteorology of the event. Flash flood guidance remains mostly unchanged with 6 hr FFG guidance generally 2.5" to 4". In terms of river flooding, little change in thinking. The latest guidance from the National Water Model, HEFS, and contingency forecasts, still suggest that the forecast NWS QPF (or most likely amounts of generally 1.5" to 3.0") would lead to within bank rises on several rivers, mainly across central and southern Iowa.

However, river flooding could become an issue, but only if rainfall amounts on the higher end of the current guidance occur. This would generally require widespread QPF amounts in the 4" to 5" range (e.g. highest 10% of QPF members). This would likely cause several rivers to hit minor flooding, with moderate or greater flooding also a possibility. This would be most likely across southern Iowa, perhaps extending nwd into central Iowa if the higher QPF shifts nwd (unlikely at this time).

DMX WATCHES/WARNINGS/ADVISORIES

Flood Watch through this evening for IAZ085-086-092>097.