textproduct: Des Moines

KEY MESSAGES

- Fog again tonight, mainly in the northeast.

- Large temperature spread for highs Wednesday, with record highs possible.

- Active weather to follow, with rain Thursday, transitioning to winter weather Thursday night, then again Friday night and Saturday.

DISCUSSION

Issued at 252 PM CST Tue Jan 6 2026

Stubborn fog and stratus continued to cover roughly the eastern half of the state this afternoon. A subtle shortwave will bring a brief window of rain chances to the far north this evening, but enough dry air in the inversion exists that QPF is little to none. A surface ridge will move across the state overnight tonight. The light and variable winds will lead to the formation of another round of dense fog tonight, mostly in the northeast half of the area, with uncertainty starting at a NW-to-SE line from Estherville to Des Moines to Ottumwa. West of these cities will be warmer, dry air that will work to move fog/stratus away earlier Wednesday. Unfortunately for the northeast part of the state, stratus will likely be stubborn to leave tomorrow. A large temperature gradient exists across the state, with highs approaching 60 in southwest Iowa, challenging records. Northeast Iowa may not get out of the low 40s tomorrow. Have leaned towards the 90th percentile of guidance in the warm sector tomorrow as dew points in the 20s and dry ground tend to lead to efficient mixing and overperforming highs.

An active second half of the week is in store. A closed low off the West Coast will encouraged a prolonged period of troughing in the western CONUS, dragging another feature from the PNW into the Four Corners. The first feature will ride the seasonally strong upper jet, tilting it negatively as it arrives in the region. The jet will round the base of the feature Thursday afternoon, but kinematics for severe weather will stay south and east of the state at this time. PWATs over an inch will come into southeast Iowa as well as midlevel lapse rates greater than 7 C/km. So, there could be efficient rain and maybe even a few thunderstorms. NBM guidance right now has a 25- 30% of seeing an inch of rain in southeast Iowa. Thursday has also trended warmer, so the transition time for snow on the northwest side has been delayed. Snowfall amounts will be challenging as the secondary DGZ is in play with a warm near-surface profile.

The aforementioned second wave will be joined by a northern stream feature. They look to combine this weekend somewhere in the region, intensifying as they do. Better congruence was seen in deterministic guidance today for Friday night, bringing the deformation zone of the developing surface low somewhere in the state, yielding a rain/snow mix. Temperatures fall going into Saturday and the extended duration of precipitation will depend on how much the warm conveyor belt wraps around (25-25% PoPs on Saturday for now). There may be an additional boundary pivoting around the mature cyclone that could use this moisture. With how dynamic the height falls are (around 15 to 20 dam) will have to watch how the simulated surface low track and intensity changes this weekend, as it will have implications for how much wind will be a factor as well.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 1044 PM CST Tue Jan 6 2026

Dense fog began to form over portions of southeast Iowa late Tuesday night, which is impacting KOTM, and is expected to expand across eastern Iowa, including at KMCW and KALO through much of Wednesday morning. Visibilities below a half to quarter mile are expected, leading to IFR and isolated LIFR conditions at times. Otherwise, uncertainty on the fog coverage further west at KDSM and especially at KFOD remains, with impacts if any looking to generally be patchy fog and low probabilities for dense fog at this time. Will continue to monitor through the night into the morning, and update as needed. Otherwise, conditions improve for all sites after 15-18z, with VFR conditions expected. Winds out of the south to southwest are expected through the day, with winds increasing into late morning through the afternoon as gusts reach up to 15 knots at times.

DMX WATCHES/WARNINGS/ADVISORIES

None.