textproduct: Des Moines

KEY MESSAGES

- Light snow will linger today, mainly across the northern half of Iowa this morning and eastern half this afternoon before departing. Additional accumulations will be light, but may result in minor travel impacts.

- A quick round of light snow will affect roughly the northeastern half of Iowa on Sunday morning, then a cold front will bring strong northwest winds, falling temperatures, and possibly snow showers Saturday afternoon and evening.

- Very cold weather is forecast from Saturday night into Sunday, as temperatures fall to near zero with northwest winds around 15-20 MPH early Monday morning. Wind chill values will fall into the teens below zero south to 20s below zero north at that time.

DISCUSSION

Issued at 217 AM CST Sat Jan 17 2026

A 500 MB low is moving slowly across Iowa early this morning and will eventually exit the southeast corner of the state later today. Within the core and wrapped around the northern and western hemisphere of the low, a large area of light snow is evident across northern Iowa and neighboring states, sinking slowly southeastward toward central Iowa at this hour. With atmospheric water content lower and the system slowly filling, significant rates/accumulations are not anticipated. However, have increased POPs to categorical (80-90%) at times this morning due to the expansive nature of the snow field, and minor travel impacts are certainly possible due to somewhat reduced visibility and slick spots on roadways. This will continue, mainly over the northern half of Iowa this morning and eastern half of Iowa by this afternoon, until the snow leaves our area late in the day. Meanwhile, gusty northwest winds will set in by this afternoon and steady cold air advection, along with persistent cloud cover, will keep temperatures in check as they will rise only about 4-8 degrees during the day with highs only in the single digits north to mid teens south.

Hot on the heels of the current 500 MB low, a series of fast- moving impulses will cruise south southeastward from canada into North Dakota and northern Minnesota early tonight. The first impulse will reach Iowa early Sunday morning, with the second traversing the state around Sunday afternoon and the third Sunday night. This wave train will have several impacts on Iowa weather during this time. At the surface, initially a high pressure area will slide down the High Plains just to our west and southwest this afternoon and tonight. By late tonight/early Sunday morning, the low-level flow behind this high will quickly turn to the southwest and increase ahead of an approaching surface trough accompanying the leading 500 MB wave. This will promote warm air advection causing temperatures to rise slightly late tonight and promoting a quick round of light snow that will move from our north central counties to our eastern counties during the morning hours. Forecast soundings show a deeply saturated Dendritic Growth Zone (DGZ) around Mason City and Waterloo for a few hours as the band of WAA precipitation moves through, however it will be moving very quickly and most soundings also indicate some near-surface dry air to overcome, so QPF and predicted snow amounts are light Sunday morning and impacts should be limited. Despite limited accumulation, the likelihood of precipitation warranted substantial increase in POPs during this time frame, peaking at 60% in our northeastern counties.

The passage of the second 500 MB impulse around Sunday afternoon is more concerning. It will be accompanied by a stronger surface cool front sweeping from northwest to southeast across Iowa. A tightening pressure gradient and impressive cold air advection behind the front will support strong northwest winds during the afternoon and evening, and have increased both wind speeds and gusts which could reach advisory criteria behind the surging front. In addition, some model solutions depict bands of frontogenetical forcing translating through beneath a quick shot of lift accompanying the mid-level impulse. Forecast soundings show a relative lack of moisture, but there is some potential for snow showers moving quickly through Sunday afternoon and have increased POPs into the 20-40% range accordingly. Given the strong winds forecast, blowing snow could cause issues if any snow showers do develop and reach the surface. Meanwhile, the NAM is resolving a band of stronger frontogenetical forcing, low surface-based instability, and resulting high snow squall parameter values just to our west over Nebraska on Sunday afternoon, so we will be monitoring this possibility as well. Confidence in strong winds Sunday afternoon/evening is thus high, while confidence in snow showers/squalls during that time is low to moderate.

From Sunday night into Monday a large arctic high pressure ridge will build rapidly from southern Canada down across the Midwestern states and Iowa, sustaining gusty northwest breezes and sending temperatures falling even further. Forecast Monday morning lows in our forecast area range in the single digits below zero north to single digits above zero south, and when combined with northwest winds of 15-20 MPH, minimum wind chill values around sunrise will reach the teens below zero south and 20s below zero north, approaching advisory levels in some areas. This will be further assessed over the weekend. Whether the values reach advisory levels or not, it will definitely be very cold Sunday night into Monday. Thereafter, 500 MB flow will generally be west northwesterly from around Tuesday through Friday, allowing for some moderation of temperatures with highs returning to the 20s and 30s on some days, and only sporadic chances for light precipitation. Not a totally quiet pattern, but no systems of high impact are foreseen during the work week, after the Monday morning cold.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 531 AM CST Sat Jan 17 2026

Low stratus clouds and light snow will prevail for much of this morning before moving off this afternoon. Mainly MVFR conditions are expected, but brief IFR visibility may occur. Amendments are possible until the snow and low ceilings move out. Also of note is that gusty northwest winds are on tap again today, resulting in 20+ crosswinds at times primarily on SW-NE runways.

DMX WATCHES/WARNINGS/ADVISORIES

None.