textproduct: Des Moines

KEY MESSAGES

- Patchy fog will persist through mid-morning before diminishing.

- Scattered showers and storms will re-develop this afternoon, most numerous along the Iowa/Missouri state-line. While an isolated strong storm is possible, widespread severe weather is not expected. Spotty heavy downpours are also likely.

- A strong upper level high pressure ridge will set up over the central U.S. this weekend into next week, bringing mostly dry conditions and very warm temperatures Sunday and beyond.

SHORT TERM /THROUGH SATURDAY/

Issued at 250 AM CDT Fri Jul 10 2026

The upper air pattern early this morning is dominated by a strengthening ridge of high pressure over the Rockies, with a nwly flow regime over the Midwest. The sfc pattern is very diffuse over IA, with virtually no change in sfc pressure, which is resulting in the very light to calm winds in most locations. While there were very isolated showers overnight across Iowa, the features of greatest interest on radar are the clusters of showers and tstms over NE and KS.

Today, still expecting patchy fog across the area through mid- morning. Otherwise, the consensus of the short term global and CAM solutions develop a remnant MCV out of the convection in NE/KS and track that feature across nrn MO and srn IA from late morning thru evening. The thermodynamic environment today will be similar to yesterday, with generally weak capping, 1000-1500 J/kg of MLCAPE, and a weak deep layer shear profile /<25 kts/. While the extent of forcing and resulting impacts from MCV's can be tricky to forecast, a majority of the CAM solutions develop at least scattered showers and thunderstorms /30% to 60%/ across southern Iowa. North of Interstate 80, coverage of storms should be less, generally <20%. As noted, the low level flow below 700mb in this regime is very weak, with some increase in wind speeds above 500mb. This lack of stronger flow/shear should limit the organization of storms in Iowa, with most models showing better shear across northern MO, where the SPC does have a Marginal/Slight risk. It should be noted that a few CAMS /HRRR, ARW, FV3/ do produce stronger winds of 50-60 mph, mostly across Missouri, but getting dangerously close to the state line. This is something we'll need to watch closely this PM. In addition, with the warm and humid, airmass in place /PWATs still ~ 1.5"/ a few pockets of heavy rainfall are possible. Little change in high temperatures today with limited temp advection, so still expecting readings in the mid 80s. In fact, if thicker clouds develop, we maybe a touch too warm with highs, especially in the south.

Tonight...with the loss of daytime heating, the shower and thunderstorm activity will diminish with clear to partly cloudy skies. Patchy fog will once again be possible, but at this point no clear signals on widespread dense fog.

Saturday...Rising upper level heights at H5 begin to build into the region from the west, while sfc high pressure expands into Iowa from the Great Lakes region. As such, expecting mostly dry conditions with any showers/tstms focused south and east of the forecast area. With a light e/nely sfc winds not expecting much change in temps on Saturday with highs again in the mid-80s.

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/

Issued at 232 PM CDT Thu Jul 9 2026

This weekend and into early next week, a mid to upper level ridge is expected to build across the central and northern plains. This will drive a warming trend alongside relatively dry conditions across the region. Highs on Saturday will approach the mid-80s with upper 80s expected by Sunday. As we head into the new work week, most of our central Iowa will push into the lower 90s. Along with the building ridge, overnight lows are expected to remain elevated in upper 60s to lower 70s. By midweek, daytime highs will peak in the lower to mid 90s as the dry spell continues. Heat indices could push mid to upper 90s in a few spots.

AVIATION /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 1058 PM CDT Thu Jul 9 2026

Trended more aggressive with fog as calm winds allowed for patchy fog to form over much of the area. Added a TEMPO group for MVFR for KDSM and KOTM, then worsened fog conditions for KALO and KMCW.

Also of note is near stationary showers near KALO that have held on. Added a TEMPO for them at the beginning.

Fog will lift to stratus through the morning, which will likely require a short (2-3 hour) MVFR cig group in the next issuance. They'll become SCT through the afternoon. Widely scattered thunderstorms still anticipated near KOTM after 20z, but coverage is too sparse to include in the TAF at this range.

HYDROLOGY

Issued at 232 PM CDT Thu Jul 9 2026

Main hydrologic focus is now on river flood potential within the Cedar basin, especially the Shell Rock and Cedar Rivers. High rainfall amounts occurred in the upper Cedar basin last night, and questions exist regarding the evolution of the crest as it travels downstream.

For the Shell Rock River, a quick rise has occurred during the day and the crest has been traveling downstream. It is expected in the Shell Rock area later today or this evening.

For the Cedar River, current river forecasts reflect a shorter-lived but higher crest, vs. a longer-lived but broader crest. Recognizing the potential magnitude of this event especially in the WFO La Crosse service area, the U.S. Geological Survey is planning to make some extra flow measurements which will help provide a more comprehensive picture of the stream's response for this event. This information will help fine-tune downstream forecasts for example in the Waterloo-Cedar Falls area.

DMX WATCHES/WARNINGS/ADVISORIES

None.