589 FXUS63 KDMX 271717 AFDDMXArea Forecast Discussion National Weather Service Des Moines IA 1217 PM CDT Sat Sep 27 2025
...Updated for the 18z Aviation Discussion...
.KEY MESSAGES...
- Weather on repeat - warm, ample sunshine, and dry conditions until at least the middle of next week.
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.DISCUSSION... Issued at 127 PM CDT Fri Sep 26 2025
There is little change in the forecast thinking today from this time yesterday with a dry and warm period expected into at least the middle of next week. Visible satellite shows no clouds over the state with the eastern edge of the broad ridge fully over the region. There is a robust upstream shortwave trough moving over the Alberta province into the Saskatchewan province with a surface cold front extending through the Dakotas. This front will drop through Iowa on Saturday. As it does so, a wind shift from the southwest to from the northwest or west will occur with slightly breezier daytime winds. Further, highs today to Saturday will be similar over southern Iowa, but about 5 to 10 degrees lower in the upper 70s over northern Iowa. There is no chance of rain as the front is moisture starved with forecast soundings showing this dry air and a precipitable water value under a half an inch. Thus, plenty of sunshine will prevail with this continuing into Sunday as surface high pressure pushes into Iowa behind the cold front.
Dry conditions will prevail through at least the first half of the week as a slowly progressive omega block moves eastward with 500mb lows over the Southeastern US and Arizona and the ridge between the two. The progression and evolution of the Southeast US low will be complicated by AL94`s arrival early next week with this slowing down the flow and causing the upstream ridge to be pinched at the bottom and/or tilted at the top. This will allow the Arizona low to lift northeastward into the Dakotas by midweek with Iowa remaining under lingering ridge influence and light flow keeping conditions dry through midweek if not late next week. Highs most days next week will be in the 80s with lows in the 50s to around 60 degrees.
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.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/... Issued at 1212 PM CDT Sat Sep 27 2025
Only weather feature of note is the cool front crossing the state at this time, extending roughly from Waterloo to Ames to Atlantic, and bringing a wind shift to the north through tonight. By Sunday morning, surface high will already be shifting off the east and southeasterly surface winds will return to the area. Otherwise, VFR conditions prevail through the TAF period.
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.DMX WATCHES/WARNINGS/ADVISORIES... None.
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DISCUSSION...Ansorge AVIATION...DMD
NWS DMX Office Area Forecast Discussion