textproduct: Des Moines

KEY MESSAGES

- Dense Fog Advisory in place for most of the area through Friday morning. Only modest improvement this afternoon before becoming thick once again this evening through Friday morning.

- Strong cold front Sunday will bring strong wind, snow showers, and tumbling temperatures.

DISCUSSION

Issued at 233 PM CST Thu Dec 25 2025

Persistent fog has blanketed the area all day, with only pockets of modest improvement. This afternoon visibility remains under 1 mile for most of the state with many areas under 1/4 miles. In a few areas saturation has increased such that light drizzle has been reported, adding to the dreary conditions on this Christmas Day. Any minor visibility improvement this afternoon will quickly reverse as dense fog is expected to fill back in across the area after sunset. With the fog signal rather stubborn thorugh Friday morning, have extended the current dense fog advisory all the way through Friday morning. While there may be periods with less dense (>1/4 mile) visibility, especially this afternoon, the overall theme is going to be soupy visibility through Friday morning.

As noted in the previous discussion, the widespread fog and stratus will mute diurnal temperature trends and have kept the going theme with warmer overnight and cooler daytime temperatures into Friday. Southern Iowa should see a little sun by midday Friday as the surface low shifts to the east, allowing for drier air from the west to filter into the area. Cross sections show this de-saturation making it through southwest and into central Iowa but the extent into central Iowa is uncertain. Area that do see a little clearing will warm through the 50s while central to northern Iowa remain cloudy and cool in the low 40s. Another push of warm air advection may help to send temperatures into the 50s again on Saturday, but this will be accompanied by moisture advection, making for another cloudy day across Iowa. It's possible that with southeast flow temperatures may be a couple degrees too warm on Saturday.

Our attention then turns to a robust trough gaining steam across the western US and set to push across Iowa Sunday. A sharp cold front will send temperatures tumbling through the day - the temperatures in the morning are expected to be the daily high. With strong cold air advection and subsidence with a tightening pressure gradient, winds will be strong. Model soundings indicated 35-40 kts at the top of the mixed layer, translating to gust of 35-40+ mph possible at the surface. At the same time, light precipitation is anticipated, first as rain before transitioning over to snow with the cold front. Any snow accumulation is light and under an inch, but when combined with the gusty winds this could make for hazardous travel on Sunday - especially for any with post-holiday travel planned. Much colder to start the week with Monday morning lows in the single digits to around 10 degrees and a Monday afternoon high in the teens to low 20s.

AVIATION /00Z TAFS THROUGH 00Z SATURDAY/

Issued at 533 PM CST Thu Dec 25 2025

Low vsbys due to dense fog across Iowa will remain tonight and through much of Friday morning, along with low stratus that will lead to continued LIFR/IFR conditions. By late morning, ceilings may lift only slightly but remain near IFR category, though fog should largely diminish with visibilities improving at least somewhat. Model guidance does again indicate the return of dense fog across much of the forecast area Friday evening, so this will be monitored closely. Winds shift northwesterly after sunrise briefly, then gradually turn southeasterly near/at the end of the forecast period.

DMX WATCHES/WARNINGS/ADVISORIES

Dense Fog Advisory until 9 AM CST Friday for IAZ004>007- 015>017-023>027-033>038-044>050-057>062-070>075-081>086- 092>097.