textproduct: Des Moines

KEY MESSAGES

- Areas of fog will persist this morning with visibility below one mile at times.

- Building high pressure aloft and at the sfc will result in dry conditions for at least the next several days.

- Seasonal mid July temperatures /highs in the 80s/ will occur today and Sunday, with a slight warming trend by mid-week /upper 80s to lower 90s/. With a easterly sfc wind, dewpoint temperatures will be modest, although will need to watch the contribution from evapotranspiration.

SHORT TERM /THROUGH SUNDAY/

Issued at 255 AM CDT Sat Jul 11 2026

The synoptic pattern in the short term will be dominated by rising 500mb heights across the Plains and Midwest, with H5 heights in the 594-597 dam range by 00Z Monday, pretty impressive. At the sfc the Great Lakes high is expected to expand westward, yielding generally an easterly component to the sfc wind. This will have some impact on temperatures and moisture.

Today...areas of fog will be the initial concern this morning. As has been discussed recently, a very diffuse sfc pattern with nearly calm winds, combined with clearing skies and residual low level moisture has resulted in a favorable raditional fog setup. Based on the depth of moisture in model soundings, feel the fog is rather shallow in depth. Nonetheless, seeing a few observation sites drop from 1/2SM to 1/4SM as of 3am, mainly across northern and western IA, where skies have cleared. We'll be monitoring if the fog becomes widespread and dense enough to warrant a Dense Fog Advisory. Expect this fog to continue through the early morning hours before gradually dissipating.

Otherwise, expecting skies to become partly to mostly sunny today as broad scale subsidence overspreads the area per rising H5 heights. A few CAMs try to pop or rogue shower over the west in vicinity of the deeper low level moisture. With weak lift and sounding showing a modest cap, will leave the forecast dry for now. Little change in the low level thermal profile, with 850mb temps hovering around +16C to +18C. This will result in high temperatures in the mid/upper 80s, generally a low spread in the probabilistic guidance. With the light E/NE sfc winds, the models are trying to advect in a drier low level airmass. In fact the RAP/HRRR are showing sfc Tds falling into the upper 50s or lower 60s in some locales. The question is how much will evapotranspiration or ET /now peaking as corn is nearing tasseling/ offset this drier airflow? This will impact not only Tds but also heat indices today and Sunday, but also into next week. For now, kept Tds in the middle of guidance envelop /mid 60s/ for now, but today will be a good benchmark.

Little change in the pattern Saturday night into Sunday. Patchy fog is possible again tonight, but with drier Tds, feel the threat is lower. Mostly sunny on Sunday, with temperatures trending up perhaps a degree or two.

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/

Issued at 237 PM CDT Fri Jul 10 2026

Dry and increasingly warm conditions are forecast from Sunday through much of next week as an upper ridge builds and tracks eastward through at least mid week. High pressure at the surface will keep winds light and skies mainly clear outside of some diurnal cumulus at times. Southerly flow starts to return early in the work week leading to warming temperatures in the upper 80s to low 90s Tuesday and beyond with heat indices topping out around the mid to occasionally upper 90s at times. Certainly warm, but looking to be below heat headline criteria. Precipitation chances then return later in the week in at least the east into Friday, though at this time range there is still a fair amount of model spread and plenty of time to refine the forecast.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 613 AM CDT Sat Jul 11 2026

As expected, fog has developed and is impacting the MCW/FOD terminals. LIFR/IFR conditions will impact MCW, with IFR/MVFR at FOD thru 13Z or 14Z, before improving. Could see a brief period of MVFR fog at DSM/ALO/OTM, otherwise VFR conditions will return for the remainder of the day. Winds will remain very light, favoring a E/NE direction today.

DMX WATCHES/WARNINGS/ADVISORIES

None.