790 FXUS63 KDMX 301857 AFDDMXArea Forecast Discussion National Weather Service Des Moines IA 157 PM CDT Tue Sep 30 2025
.KEY MESSAGES...
- Warm and dry through the end of the week. Becoming breezy Friday through the weekend.
- Precipitation chances return to the area by Sunday.
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.DISCUSSION... Issued at 157 PM CDT Tue Sep 30 2025
High clouds have spread across much of Iowa this afternoon where a plume of midlevel moisture has lifted into the area, sandwiched between a trough to the west and the high central and east that continues to dominate the upper level pattern this week. The primary impact has been a couple degree reduction in temperatures so far today, though highs remain in the 80s and well above average. In areas with less cloud cover, daytime heating has allowed for deeper mixing and breezier gusts near 20 mph. As an embedded shortwave passes north of the area this plume of moisture will gradually shift across and east of the area through Wednesday with continued high clouds. Even so, we will continue to see warm temperatures into the mid to upper 80s. By Thursday to Friday (and into Saturday), temperatures may brush the low 90s.
The western US trough finally approaches the area this weekend. The first influence will be the tightening pressure gradient across the area, accompanied by dry low levels and deep mixing. Model soundings indicate parts of northern Iowa with gusts of 35+ kts and into central Iowa gusts of 25-30 kts. Have increased winds through Saturday and into Sunday to account for this, though further adjustments are likely in the days to come. While not in the realm of headline criteria (for wind or fire), these breezier conditions will heighten fire weather conditions this weekend with the harvest well underway.
As has been discussed the past few discussions, the blocking high and eastern US tropical systems have slowed the progression of the western US trough. And while this should finally come to an end this weekend, the onset has slowed another 12-24 hrs with recent guidance delaying precipitation into Iowa until Sunday.
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.AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1233 PM CDT Tue Sep 30 2025
VFR conditions will persist through the TAF period. High clouds remain in place across the area, especially towards western Iowa. Areas without cloud cover have seen deeper mixing this afternoon with gusts near 20 kts, however most TAF sites are clouded in and less likely to see gusts so have kept from TAFs at this time.
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.DMX WATCHES/WARNINGS/ADVISORIES... None.
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DISCUSSION...Hagenhoff AVIATION...Hagenhoff
NWS DMX Office Area Forecast Discussion