textproduct: Des Moines

KEY MESSAGES

- Breezy conditions subside this evening, then areas of fog, perhaps dense, are possible tonight.

- More widespread patchy to dense fog possible Monday night into Tuesday, then a very low chance for precipitation far north (10% or less)

- Generally warmer through Wednesday with near record highs possible by Wednesday.

DISCUSSION

Issued at 217 PM CST Sun Jan 4 2026

Dry weather persists across much of central Iowa this afternoon, with thick cloud cover remaining across the northeastern/eastern portions of the state while skies are gradually clearing across much of western Iowa, which will continue to clear eastwards into this evening. A look at the surface map indicates the weak system responsible for these clouds centered over eastern South Dakota and far southwestern Minnesota this afternoon, with light wintery precipitation occurring over Minnesota. Weak radar returns have been over northern Iowa throughout much of the day with this system's passage, though dry air has lead to virtually no precipitation to reach the ground. Soundings indicate additional drying yet this afternoon which likely is due to the breezy southeasterly winds across much of the state, with warm air advection spreading into the region. Winds are behaving generally as forecast, with gusts increasing to 20-30 knots across Iowa, highest northwest, while Estherville as had some isolated higher gusts up around 35 knots at times. These winds will continue to be breezy through the rest of the afternoon, turning light through the evening and gradually shifting west/northwesterly. While dry conditions are expected to remain as the system departs later this afternoon and especially by the evening, clearing skies, lingering low to mid level moisture over northern Iowa, and light winds may lead to developing patchy to locally dense fog late tonight through Monday morning over north to north central Iowa. There is potential for this to develop further south given some indications of latest guidance so will have to watch this closely.

Much of Monday will be dry as south/southeasterly winds keep mild conditions with highs in the 40s to low 50s. While generally quiet, Iowa will be between two waves as the previous system continues to depart eastward, while further west, another shortwave in the western CONUS develops another surface low that is slated to pass over Iowa Monday evening to Tuesday. Moisture returns with this system, particularly over northern Iowa in the mid levels, though the higher concentrations remain closer to the band of mid-level frontogenesis depicted over southern Minnesota into Central Wisconsin. A deeper dive into soundings across northern Iowa shows some low level saturation near the surface but is very thin per the RAP, with otherwise plenty of dry air that would suggest some difficulty for any generated precipitation to reach the ground, while the NAM is at least a bit more saturation below 1km though still lacking enough depth. Would favor remaining with a dry forecast during this time period given these limiting factors, though any southern shift would lead to better potential across the north so will monitor over the next few forecast cycles. Otherwise, the indication of some low level saturation, along with an increasing surface inversion and light winds is suggesting the potential for widespread patchy to dense fog Monday night into Tuesday. Models such as the HREF and HRRR indicate reduced visibilities due to these conditions, with values near to below a mile for many locations. Will have to monitor trends through Monday, adding fog into the forecast as the likelihood increases.

Any fog gradually departs late Tuesday morning and especially by the afternoon as the surface low departs across the Great Lakes, replaced by passing weak high pressure as the large flow pattern returns more quasi-zonal into midweek. Stratus Tuesday will likely be slow to exit, which may put a damper on the current forecast highs mainly across the northeast half of the state in the upper 30s to 40s, so expect some nudging of values a bit cooler over the next few forecast cycles. Wednesday remains mild and dry with south/southwest winds, allowing for highs to reach into the 40s to mid 50s, warmest southwest under mostly clear skies. By Thursday, there is some indication of another northern stream shortwave tracking across the upper Midwest, with some indication of a boundary signaled to clip northern Iowa quickly through the morning per GFS, though the Euro is more muted with a weaker system further north not impacting the region at all. Therefore, keeping the forecast dry for this time period.

The most noteworthy period of interest in terms of potential impactful systems is the deepening mid-level trough that could bring more of an active period of weather into Iowa late in the work week. Per GFS, the trough gradually lifts northeast into the CONUS late Thursday into Friday, with the surface low pressure generally staying now further south and east of Iowa as it looks to track across Arkansas/Missouri into the Ohio Valley through Friday. With Iowa now generally in the cool sector of this system and some increase in moisture looking to fill in over south/east Iowa, there still remains the potential to see some wintery precipitation. At about the same time, further north over the Upper Midwest, another deepening trough looks to sink into the region, with a cooler airmass moving in just behind this into Saturday as northwesterly flow settles overhead. The two aforementioned systems then gradually phase together as they depart to the east out of the region, becoming one very dynamic system as it nears the Atlantic Saturday. The overall evolution of these features late week is only from one solution as mentioned (GFS), which looking at the Euro indicates the southern trough located much further north, with the warm sector reaching into southeast Iowa into Friday and much more widespread precipitation chances across the state. Then solutions come into somewhat better agreement by Saturday with the phasing of systems and the bringing of cooler air into the region. The very different solutions into the late work week are normal this far out and will become clearer in the coming days as more models latch onto this time period, so stay tuned for updates through the week.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 547 PM CST Sun Jan 4 2026

A period of low level wind shear is ongoing, but will dissipate from west to east toward and shortly after 6z. Then, will be watching as stratus clouds spread in from the northwest over northern and central Iowa with low end MVFR restrictions common and growing confidence in higher end IFR restrictions over northern Iowa. The stratus will near DSM, but confidence to keep VFR ceilings at this time. Other concern will be fog developing beneath the stratus and to what extent. While guidance is bullish showing LIFR, will keep MVFR/IFR and watch trends this evening. Ceilings and visibility restrictions are forecast to lift by late Monday morning or early afternoon.

DMX WATCHES/WARNINGS/ADVISORIES

None.