233 FXUS63 KDMX 250535 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 1235 AM CDT Thu Jun 25 2026 ...Updated for the 06z Aviation Discussion... .KEY MESSAGES... - A shower or storm possible over the far northeast this afternoon and the far southwest tonight. - More precipitation possible later Thursday night and Friday central and south. - Hot and humid conditions arriving by Sunday and into next week. Heat index values over 100 expected. && .SHORT TERM /THROUGH FRIDAY/... Issued at 234 PM CDT Wed Jun 24 2026 Short wave trough currently moving across Minnesota and Wisconsin along with a boundary extending from northwest Wisconsin and into central Iowa. A plume of higher dewpoints in the 60s has pooled ahead of the boundary and an axis of 1000+ J/kg MLCAPE had developed in this region. Sounding profiles show mostly narrow CAPE with the top of the CAPE region also aligned with an area with much strong flow aloft that could lead to shear overwhelming updrafts especially considering the main forcing mechanism is the sfc boundary. Note the stronger forcing is north and east associate with the upper short wave. There have been a few failed attempts at convective initiation (CI) south of Des Moines. Failed CI will likely be the case for most areas today remaining dry with a few instances of agitated cumulus outside the potential for a storm or two over the far northeast and closer to the greater forcing. Another area of storms is moving across northwest Nebraska and into southwest South Dakota. That activity should remain west of the area though there is a noted secondary instability axis that is across northern Missouri and could help sustain precipitation long enough to reach parts of southwest Iowa. This precipitation could linger over far southern Iowa Thursday morning, otherwise, dry conditions are expected the remainder of the day with partly to mostly cloudy skies with highs in the mid to upper 70s. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Issued at 234 PM CDT Wed Jun 24 2026 Theta-e advection will lift into Iowa Thursday night and Friday as an upper low pressure begins to descend from the Gulf of Alaska with troughing extending across the entire western CONUS. This will lead to 1000-500 mb height rises into Iowa and the push of theta-e advection northward. Showers and a few storms will be possible, mainly over central and southern Iowa. A more significant push of theta-e advection and of much warmer temperatures begins Saturday afternoon and night as the upper low further descends into the Pacific Northwest while a sub-tropical high begins to form over the Lower Mississippi Valley. Note, the location of the sub-tropical high has been trending west the past 48 hours, which would place Iowa in potentially an even warmer/drier solution. Still the potential for elevated convection as the theta-e advection and instability/low level jet pass through Iowa. A stout elevated mixed later should then develop leading to hot and humid conditions for Sunday and Monday. Highs in the 90s and heat index values over 100 are expected. Still monitoring Tuesday/Wednesday as potential timeframe where the sub-tropical high flattens some as the western upper low moves northeast. This could lead MCS develop and track into parts of Iowa that may suppress the heat, at least across northern Iowa. A sneak peek beyond Wednesday does look like the sub- tropical high becomes re-established even further north bringing back the heat, potential for the end of next week and into the Fourth of July weekend. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 1229 AM CDT Thu Jun 25 2026 Fairly quiet TAFs are in store as surface high pressure largely dominates the period. A passing disturbance to the southwest will bring increased clouds to KDSM and KOTM Thursday afternoon but CIGS are expected to be around 10K ft. Also, afternoon cumulus is forecast to develop around 4K to 5K with increased winds from the northwest will impact the remaining TAF sites but when sunset arrives, winds will diminish to light and variable. && .DMX WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Donavon LONG TERM...Donavon AVIATION...Vorst
