textproduct: Des Moines

KEY MESSAGES

- Dry conditions are expected with a warming trend through the first part of this week.

- Breezy winds over western Iowa today and much of Iowa Tuesday.

- Scattered thunderstorms return and are possible late Thursday into early Friday, especially over western and southern Iowa.

SHORT TERM /THROUGH TONIGHT/

Issued at 207 AM CDT Mon Oct 5 2026

It is a clear sky over the state of Iowa early this morning as viewed from GOES-East Nighttime Microphysics RGB imagery. As has been the case in general the last few nights, there have been a surface observation or two that has reported fog. It is a good setup for fog with the clear sky, light winds due to high pressure nosing over the state, and recent wet conditions. The one site that is reporting fog in the state is Lamoni, but viewing Iowa DOT cameras in the area do not reveal any fog present. From personal experience Sunday morning seeing a fog patch in the Beaver Creek valley in Johnston, IA, the fog may be very localized. From a forecast standpoint, the HRRR has been the most consistent model with fog generation and has trended toward less fog and the rest of the models do not develop any fog at all. Forecast soundings point to too much dry air in the low levels with near saturation not achieved, even in the HRRR as well as the NAM, which tends to show more cooling/saturation than reality. All this said, the forecast continues without fog mentions this morning.

As the high pressure region departs to the east today, will see winds become a bit breezier as the pressure gradient tightens, especially over the western half of the state. Increased sustained winds from the initial National Blend of Models (NBM), but gusts from the NBM seemed representative when viewing top of the mixed layer winds in soundings. The same soundings reveal a similar signal for good boundary layer mixing, which will warm and dry the surface temperature and dewpoints. Sunday's forecast highs were adjusted upward toward the 75th percentile of model guidance and this was not enough compared to observed highs. So, will give it another go with a bit more upward adjustment using a blend of NBM 50th and 90th. Comparing this adjustment to MOS guidance has forecast temperatures on par or within a degree of the highest MOS, which is the MAV. On the dewpoint side, lowered dewpoints toward a blend of the NBM and 10th percentile of model guidance. This will push relative humidity values back solidly into the 30 percent range. The HRRR tends to overmix, but even if some part of that verifies this may push dewpoints below 30% in a few places. Tonight will see a continuation of dry conditions under a mainly clear sky. Winds will stay breezy beneath low level warm air advection so lows by daybreak Tuesday will remain in the 50s, which will be about 10 degrees warmer than Monday morning.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 224 PM CDT Sun Oct 4 2026

A slowly building area of large scale ridging will lead to persistent upper-level northwest flow into the Midwest region throughout the remainder of the work week. Dry conditions are expected to keep hold, with warming temperatures Tuesday as increasing 850mb temps move into the state, especially west around 18-20C, and increasing winds from a tightened pressure gradient and efficient daytime mixing, leading to highs in the mid to upper 70s across Central Iowa. An area of Canadian high pressure sinks down into the region once again by midweek, with temperatures a touch cooler in the low to mid 70s forecast as winds shift north/northwesterly. By Thursday into Friday, a weak shortwave descending the eastern fringe of the aforementioned ridge looks to make its way into Iowa, with a return of mid-level moisture and forcing that will introduce the next potential for rain/storm activity. The GFS is showing coverage over the southwest portion of the state Thursday evening into Friday, with dry conditions elsewhere given the lingering area of high pressure centered over the Ohio Valley. The Euro however has a direct west to east passage of this activity across Central Iowa Thursday afternoon to evening. Certainly notable differences between long range models, but consensus on rain and storms returning somewhere nonetheless, so will have to monitor trends over the next several days to better pinpoint coverage and timing details. Late week into the weekend shows a building ridge over the central US, with temperatures warming overhead as highs in the mid to upper 70s are expected, along with a return of dry conditions once again, but also notably breezy.

AVIATION /06Z TAFS THROUGH 06Z TUESDAY/

Issued at 1041 PM CDT Sun Oct 4 2026

VFR conditions are expected to prevail through the TAF period at all sites. Winds will be light and variable through the night before shifting to southerly and increasing slightly late Monday morning from west to east. Low fog potential still exists through the morning, but confidence is too low of occurrence at any terminal so have left out of the TAFs.

DMX WATCHES/WARNINGS/ADVISORIES

None.