textproduct: Des Moines

KEY MESSAGES

- Snow showers and squalls are likely today, beginning in the northwest after sunrise and spreading across the forecast area by this afternoon. A Winter Weather Advisory is in effect. While snowfall accumulations will generally be light and intermittent, sudden, intense visibility reductions are likely during snow squalls and could significantly impact travel conditions.

- Colder temperatures are forecast tonight through Saturday, then again late Sunday into Monday. Wind chill values will approach 20 to 25 below zero in northern Iowa Monday morning.

DISCUSSION

Issued at 206 AM CST Fri Jan 16 2026

A broad 500 MB trough is sinking from south central Canada into the Upper Midwest region currently, and is characterized by several distinct PV anomalies moving through the larger trough. The first of these is currently crossing Iowa and pushing through a surface trough with winds shifting to northwest in our area. Light precipitation is also being generated, mainly in our northeastern counties where some stations are reporting light snow with visibility of 1-2 miles. However, this precip. is transient and will produce little accumulation before exiting the CWA in a few hours. The second 500 MB vorticity maximum will cross eastern South Dakota this afternoon and Iowa tonight. However, between these two systems, during the day today, cold air advection behind the first trough will cool the column considerably. Forecast soundings show 850 MB temps falling by around 10 C during the day, resulting in saturation through the Dendritic Growth Zone (DGZ) along with the development of weak surface-based instability and ribbons of enhanced low-level frontogenetical forcing. Many short-range models depict strips of SBCAPE as high as 50-80 J/KG from around midday through the afternoon. This is a classic set-up for snow squalls, with forcing and saturation in the DGZ, strong winds at the surface and aloft, instability and turbulent mixing promoting rapid onset of intense snow bursts and blowing snow. This threat has been well messaged by previous shifts and the Winter Weather Advisory remains in effect and unchanged at this time. If and when snow squalls do form, likely reaching our northwestern counties shortly after sunrise this morning and spreading across much of the area by this afternoon, then warnings may be necessitated to convey the threat on smaller temporal and spatial scales. Certainly anyone planning travel today needs to pay close attention to these updates and know what to do if they encounter a snow squall. Not only can they cause rapid onset of very low visibility, but also rapid icing of road surfaces due to quick snowfall and potentially a flash freeze if temperatures fall rapidly enough. The good news is that due to the transient nature of the snow showers/squalls today any accumulations will be light, however, once again travel impacts could be significant at least within heavier bands/squalls.

Tonight and Saturday, as the second 500 MB PV anomaly mentioned earlier moves overhead, it will promote continuing cloud cover and weak forcing aloft. Forecast soundings indicate that decent column saturation will persist during this time, however temperatures will fall even farther and be well below the DGZ so snowfall rates will be much lower and probably more in the form of flurries with rapidly diminishing impacts after this evening. A third PV anomaly will finally push the main 500 MB trough axis through the region around Sunday night. Ahead of this third wave, late Saturday night into Sunday low-level winds will come around to southwest and temperatures will warm somewhat, likely rising above freezing in at least our southwestern counties, but another sharp surface front will surge through concurrent with the third wave aloft, pushing temperatures back down again and bringing another round of blustery northwest winds late Sunday into Monday. In fact, the low-level cold air advection will be quite a bit stronger around Sunday evening/night than today, and by Monday morning temperatures will fall into the single digits below zero north to single digits above zero south, with wind chill values at sunrise Monday ranging from around -10 in the south to near -25 in the far north. The good news is that after the main 500 MB trough pushes off Monday, the synoptic pattern becomes notably quieter as a generally west northwesterly flow regime sets in promoting mostly dry weather and moderating temperatures from Tuesday into the later part of the week.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 524 AM CST Fri Jan 16 2026

Tricky aviation forecast today as narrow bands of snow showers/squalls are expected to move through the area. This will result in highly variable conditions across short distances, with VFR/unrestricted conditions sometimes only a handful of miles away from near whiteout/LIFR or lower conditions. Believe best approach is to use PROB30 groups for IFR visibility during the most likely squall hours, roughly late morning to this evening, and anticipate amendments through the day based on short term observational and radar trends. The squall threat will taper off this evening, but light snow and prevailing MVFR ceilings may then move in overnight especially at ALO/MCW. Strong winds are also forecast today, resulting in 20+ KT crosswinds on some runways.

DMX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory until 9 PM CST this evening for IAZ004>007-015>017-023>026-033>036-044>046.

Winter Weather Advisory until 9 PM CST this evening for IAZ027-028-037>039-047>050-057>062.