textproduct: Des Moines

KEY MESSAGES

- High Wind Warning remains in effect central and north for gusts potentially 60+ mph this morning. Wind Advisory south for wind gusts near 50 mph.

- Light snow is possible mainly over northern Iowa late tonight into Saturday morning, with accumulations up to an inch possible.

- A significant winter storm will impact the region this weekend with heavy snow, strong winds, and blizzard conditions all possible between around Saturday night and Sunday night. However, the location of heaviest snowfall and highest impacts is most likely across Minnesota and Wisconsin, including portions of Iowa. The Winter Storm Watch now includes areas of north central to central Iowa.

UPDATE

Issued at 419 AM CDT Fri Mar 13 2026

A tightly wound area of low pressure continues to slide slowly eastward early this morning, with it's center over northwestern Wisconsin, while over Iowa a tight pressure gradient is noted. This gradient, along with strong cold air advection aloft reaching the surface has lead to very gusty winds across the state last night and into this morning, with several reported gusts up to 55-60 mph all the way down past the I-80 corridor. However, even higher occasional gusts have been reported largely over northern Iowa, with peak gusts up to 64 mph at Estherville and a whopping 69 mph at Mason City! Over southern Iowa, gusts have generally been reported between 40-50 mph. Overall, the wind headlines out have been verifying well, and given that expectations have not changed in terms of end times for the High Wind Warnings and Wind Advisories respectively, no notable changes have occurred. Expecting winds to decrease slowly through the rest of the morning from west to east, with areas west of I-35 ending their headlines by 7am and areas east of I-35 ending by 15z. Cannot completely rule out a slight extension in time to the east if winds are slower than expected to weaken, as a few model members such as the HRRR suggest. Will be monitoring through the morning.

No significant changes have occurred regarding the potential for light snow accumulations mainly over northern Iowa late tonight into Saturday morning. Accumulations are most likely over far northern/northeastern Iowa where model soundings indicate a better setup for sufficient saturation and lift at least for a few hours Saturday morning to see snow amounts approaching an inch by daybreak. Those traveling in these areas should plan accordingly for slick conditions.

The significant winter storm arriving this weekend over the Midwest per latest guidance has trended slightly southward in terms of at least slightly higher snowfall amounts, but especially the coverage of gusty winds that overall has increased confidence in a wider area of coverage in blizzard conditions further south over Iowa. Coordination with neighboring offices this morning has led to an expansion in area of the Winter Storm Watch further south to now include north central to central Iowa, extending just south of Interstate 80, hinging more so on the potential impacts due to blizzard conditions despite the lower snowfall amounts in the current forecast. Given this system is still about a few days out, would expect some slight wobbles in the overall placement of higher snowfall amounts, but again in terms of snow plus gusty winds leading to blizzard conditions, the area of coverage has increased in likelihood, hence the wider area of the headline. Further adjustments and eventual conversions are expected within the next day or so. Please plan accordingly for large scale travel impacts due to hazardous winter weather conditions.

SHORT TERM /THROUGH SATURDAY/

Issued at 237 PM CDT Thu Mar 12 2026

As the surface trough surges through overnight, winds will then shift to west northwest and increase even further, especially across the northern half of Iowa where pressure rises and 925 MB winds will be strongest, and supported by another tight pressure gradient and strong cold air advection. While some deterministic models have backed off slightly on surface wind speeds and gusts in the north overnight, the bulk of solutions and the synoptic set-up still clearly favor wind gusts to around 60 MPH in the north, and the High Wind Warning remains in effect.

On Friday the storm system to our north will move rapidly away over the Great Lakes region, replaced by a surface high pressure ridge building from Minnesota down into Iowa by the end of the day. This will support quieter weather with rapidly diminishing winds Friday morning into the afternoon. Unfortunately this brief quiet period will be far too short, as by Friday evening an even more impactful storm system will be entering the western U.S. Initially, brisk 500 MB flow will be from the west northwest over Iowa, then on Saturday as a highly energetic trough digs into the northwestern U.S., the flow over Iowa will pivot to zonal/westerly, then southwesterly by Saturday night as the trough quickly approaches. From Friday night into Saturday, a subtle mid-level impulse and associated isentropic lift will scoot eastward across the region, spreading a band of light snow across parts of our area. Initially it will be fighting low-level dry air within the high pressure ridge, but as the ridge subsequently moves away to the east snow should fall most likely across our northern counties, but with some flakes possible farther south as well. Limited moisture and forcing will preclude any heavy precipitation and only minimal snow accumulations are anticipated, but there could be some spotty travel impacts late Friday night into Saturday morning, mainly across northern Iowa.

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/

Issued at 237 PM CDT Thu Mar 12 2026

While the light snow will move away Saturday morning, it will prove only a tiny sample of what is to come as the aforementioned strong 500 MB trough moves off the Rockies Saturday night and Sunday. The surface low spinning up along its forward flank will cross Kansas Saturday night, then track across Missouri, southeastern Iowa, and Illinois on Sunday. All signs point to a widespread, significant precipitation event along the northern and western hemisphere of this low, and POPs are near 100% accordingly. The area of most significant impact will be within the TROWAL region that develops along the northwestern periphery of the cyclone, where enhanced and prolonged lift and colder temperatures will allow for a swath of potentially very heavy snowfall. Farther south and closer to the low, relatively warmer near-surface air wrapping around the system will make precipitation types more mixed, with rain, thunderstorms, a wintry mix, and snow all possible at times. This will reduce overall snow amounts closer to the low, but at least some travel impacts are still likely. The primary question as it regards potential hazards, then, is where precisely the low center will track, when and where the TROWAL will develop, and where the resulting swath of heavier snowfall accumulations will lie. The bulk of model solutions have consistently painted this swath across the southern half of Minnesota, Wisconsin, and far northern and northeastern Iowa. However, with the system still more than two days out and actually not even having entered the western U.S. observational data network yet, a northward or southward shift is still entirely possible. In conjunction with the threat of heavy snow, very strong winds are also once again forecast on the backside of the passing cyclone, with forecast soundings already depicting top of the mixed layer winds around 55-65 KT across northern Iowa. Wherever the swath of heaviest snow falls, these very strong winds will greatly exacerbate impacts which could be severe. Given the potential for significant impacts due to possibly heavy snowfall along with the strong winds, have issued a Winter Storm Watch for our far northern counties, where both confidence levels and potential magnitude of impact are highest, and we will be assessing for possible expansion and/or upgrade over the next couple of days. This winter storm system bears very close watching for any residents across the region, especially those with any travel plans between Saturday night and Monday.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 653 AM CDT Fri Mar 13 2026

Gusty northwest winds will continue to diminish this morning and especially this afternoon across all terminals, then gradually shift easterly after 00z. MVFR ceilings have become common over northern Iowa, which are more widespread in coverage than previously expected, and to a lesser degree over KDSM. This stratus will likely remain at least over the next few hours, though break apart through the morning as the system responsible for these clouds departs further eastward and dry air continues to filter into the state. Mid-level clouds return this evening into Saturday ahead of light snow chances arriving mainly at the northern terminals, while areas south should remain dry given dry air overhead but will monitor through today.

DMX WATCHES/WARNINGS/ADVISORIES

Winter Storm Watch from Saturday evening through Monday morning for IAZ004>007-015>017-023>028. High Wind Warning until 10 AM CDT this morning for IAZ007-017- 026>028-036>039-048>050-060>062. Winter Storm Watch from Sunday evening through Monday morning for IAZ033>039-045>050-058>062. Wind Advisory until 10 AM CDT this morning for IAZ073>075- 084>086-095>097.