textproduct: Des Moines

KEY MESSAGES

- Dense Fog Advisory in effect for the majority of central Iowa until 10am, then improving as winds increase and light rain quickly passes through.

- Becoming windy into Tuesday evening through Wednesday morning as much colder air arrives in the area. Wind gusts of 35-45+ mph possible. A Wind Advisory for much of Iowa.

- Light snow accumulations expected in northern Iowa late tonight into Wednesday morning, with blowing snow possible as well.

- Highs in the 30s Wednesday through the upcoming weekend. Wintry weather is possible Friday into the weekend, however specific details are uncertain at this time.

DISCUSSION

Issued at 402 AM CST Tue Nov 25 2025

Surface observations early this morning show an area of high pressure over Iowa, with light winds and cloud cover overhead. The light rain that moved though yesterday has generally ended early on this morning, but this fresh moisture over Iowa, along with light and variable winds have allowed for widespread fog to form last night into early this morning. The majority of the CWA is reporting visibilities around a half mile or less due to dense fog, and with little change expected in these conditions through much of the morning, have issued a Dense Fog Advisory for the greater majority of Central Iowa, which is in effect until 10am. Increasing winds will dissipate this fog by late morning, improving conditions. A currently weak area of surface low pressure is still on track to gradually deepen today, tracking eastward across the Upper Midwest. A cold front in relation to this system is expected to arrive into western Iowa late this morning and move eastward across the state into the evening, which will bring at least low end chances for additional rain showers mainly over central to eastern Iowa, with light accumulations around a tenth or less. Of bigger interest is what follows as the tightening system and significantly increasing northwest winds as strong cold air advection arrives will bring windy and chilly conditions into Iowa into Tuesday evening and remain into Wednesday. Model soundings indicate a widespread increasing trend in winds, with gusts at the top of the mixed layer around 45-50 knots for much of the state, along with average values up to 35-40 knots reaching the surface. Therefore have coordinated an increase in coverage to the Wind Advisory to include much of Central Iowa for this evening through early Wednesday morning, while portions of southwest Iowa look to remain near to just below thresholds but still quite breezy regardless.

In terms of potential precipitation with this system in the region, the bulk of forcing with this system will be in Minnesota to Wisconsin were more significant winter weather is looking likely Tuesday into Wednesday morning, though conditions are looking favorable at least for some light snow accumulations to extend down into far northern Iowa. Models generally indicate values around an inch across northern Iowa, though some CAMS indicate some slightly higher amounts of 2 inches or so. The differences that exist leave some uncertainty, but have enough confidence that some light accumulations are looking more likely, so have increased snow values slightly to account for this. Since gusty conditions are also anticipated during this time, there is the potential for blowing snow to be at least some concern, though in terms of more significant impacts, this looks to remain further north and west of Iowa, so any winter headlines for this time frame are not currently expected but will continue to be closely monitored. The main thing to keep in mind is that even light snow accumulations could be hazardous for those traveling Wednesday morning in northern Iowa, so please so stay tuned for updates and plan accordingly. Gusty winds gradually decrease through Wednesday morning, then decrease further as high pressure out of the northwestern CONUS drops into the region, which will give Iowa a few days of quieter weather but remaining chilly through Thanksgiving. Lows are expected in the teens to low 20s across central Iowa, with highs only in the 30s.

All eyes turn to the post Thanksgiving forecast, as the latest models look to be in better agreement in terms of timing and placement with the next system that looks to bring the next chance for more widespread winter weather into Iowa Friday afternoon to evening, with increasing chances for accumulating snow into the weekend. Many questions still remain though on exact timing, precip type and amounts, so please stay tuned for more details over the next few days as details continue to come into focus.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 543 AM CST Tue Nov 25 2025

Widespread dense fog remains across Iowa with LIFR conditions, though will dissipate by late this morning. Low clouds however are expected to remain for most of the day, improving mainly to MVFR by the afternoon and even brief VFR at KDSM and KOTM this afternoon before widespread MVFR/IFR ceilings move back in. Light rain showers are possible later this morning to afternoon, with low probabilities which were handled with PROB30 groups. Light snow is possible over the northern terminals tonight into Wednesday morning as well, which have been included especially at KMCW where highest chances are expected for occurrence. Otherwise, winds are expected to increase this afternoon and especially this evening out of the northwest, with gusts up to 40 knots across the terminals this evening through Wednesday morning.

DMX WATCHES/WARNINGS/ADVISORIES

Wind Advisory from 6 PM this evening to 6 AM CST Wednesday for IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>073. Dense Fog Advisory until 10 AM CST this morning for IAZ023>028- 033>039-044>050-057>062-070>075-081>086-092>097. Wind Advisory from midnight tonight to 6 AM CST Wednesday for IAZ074-075-084>086-095>097.