textproduct: Des Moines

KEY MESSAGES

- Becoming windy tonight and may approach Wind Advisory Criteria in a few areas late this evening and overnight.

- Colder Wednesday followed by light snow chances Thursday.

- Monitoring snow squall potential late Thursday night and Friday as a strong cold front arrives.

DISCUSSION

Issued at 240 PM CST Tue Jan 13 2026

Hopefully everyone had an opportunity to enjoy the warm weather today since we may not see these temperatures again in central Iowa for awhile with a pattern change coming. Currently, there is a ribbon of precipitation extending from southeast Nebraska to southwest South Dakota along a thermal gradient aloft and fueled further by a weak short wave passing over the gradient. This forcing does extend into southwest Iowa but the airmass below the high cloud bases (AOA 10 kft) remains quite dry therefore, not expecting much more than sprinkles.

A strong area of low pressure is moving into southeast Quebec today with mostly warm downslope flow from the west/west northwest in the southwest quad of the system, including Iowa. The primary cold front associated with the system is just now crossing the International border into North Dakota and Minnesota with temperatures in the single digits and teens along with dew point values near to below zero. That airmass will be driven southward and reach Iowa late tonight and into Wednesday, albeit in a modified form as the airmass warms some with the lack of snow cover across the state and into parts of Minnesota. The pressure gradient across Iowa will increase ahead of the surface boundary and mixing will increase due to differential cold advection between the surface and the earlier arrival aloft. Numerous deterministic models' soundings have mixed layer winds at 40+ kts and upon initial review, would suggest the potential for advisory criteria winds (sustained 30 mph/1 hr or gust to 45 mph). The modification of the airmass as it moves towards Iowa will minimize the strength of the cold and thus the mixing efficiency of these peak mixed layer winds to the surface. Since it appears to be a marginal headline case and the uncertainty of mixing efficiency and the lack of any headline criteria observations upstream, will hold off on a Wind Advisory for now and we will continue to monitor into this evening.

High pressure will drop into Iowa during the day on Wednesday and should help scour the stratus out of the area, though some mid to high level clouds may remain. The high pressure ridge will pass across the state Wednesday night from northwest to southeast with theta-e advection aloft commencing overnight that will lead to increasing clouds and surface return flow beginning after midnight over the west. Sounding profiles maintain some steeper lapse rates just above the surface that will limit some of the potential decoupling within the boundary layer. This all should prevent temperatures from bottoming out and temperatures likely will become steady or rising across the west late. After a brief passing of some thermal ridging early on Thursday, another strong short wave will descend south towards Iowa. This should lead to an area of light snow developing over parts of central and eastern Iowa with some accumulations possible.

Another strong surge of more Arctic type air arrives late Thursday night into Friday morning. The NAM/GFS deterministic soundings are showing a deep saturated layer with steep lapse rates that run from the surface to near 700 mb, which runs through the dendritic growth zone. Both models are also showing surface based instability up to 100 J/kg as strong frontogenetical forcing moves across the state. This all points to the potential for impactful snow squalls including strong and gusty winds. This is by far the deepest saturation and instability potential that has shown up over Iowa this winter season. We will continue to monitor this situation and will also continue to allude to winter impacts with our message for this time period. Wind headlines are possible should the winter impacts not materialize on Friday.

The cold air will continue to settle south into Iowa through Saturday with the chance for some warm advection on Sunday. The NBM temperatures for Saturday and Saturday night continue to remain much too warm as it tries to apply recent warm biases while trying to play catchup to this cooling trend. Raw model guidance blends are 6 - 8 degrees cooler and prefer those temperatures. Saturday will remain blustery with gusty northwest winds persisting. Light snow may be possible again on Sunday as the weak warm advection arrives and the next short wave.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 525 PM CST Tue Jan 13 2026

A cool front will move through the area overnight, bringing surging NW winds and low stratus clouds to the northern terminals within the next couple of hours and eventually to OTM by around 06-07Z or so. The cloud field is not continuous, with areas of ceilings interspersed with areas of relative clearing. In addition, observed ceiling heights upstream are variable between about FL025 and FL035 so VFR and MVFR conditions will likely alternate for much of the night at our terminals. For now have maintained prevailing MVFR groups at the three northern sites, with TEMPO groups initially at MCW and ALO, but amendments are likely overnight based on short-term satellite and observational trends. Skies will gradually clear around Wednesday morning.

DMX WATCHES/WARNINGS/ADVISORIES

None.