textproduct: Des Moines

KEY MESSAGES

- More chances for accumulating snow return to at least the southern half of the state on Monday. Snowfall amounts of 2 to 4 inches are possible in southern Iowa, with amounts generally around an inch or less farther north.

- Cold temperatures continue through the week. Coldest temperatures will be overnight Wednesday into Thursday morning with wind chills in the teens below zero possible.

DISCUSSION

Issued at 248 PM CST Sun Nov 30 2025

With our weekend system departing to the east and high pressure filling in behind, winds are diminishing over the state. With this high pressure has come cooler air and temperatures have only reached the upper teens to low twenties early this afternoon. Currently, skies are mostly clear over northern Iowa and remain clouded in over southern Iowa. This stratus deck is sitting right on the edge of the dendritic growth zone, which has allowed for transient flurries today. The evolution of the cloud deck through the night will impact overnight lows, as clearer skies will allow temperatures to cool more than cloudy skies. Stratus may fill in some, but will generally be thin and patchy through the night, which will allow some locations to cool considerably, especially in the north and east. Should temperatures really drop out, some of the guidance is trying to produce fog in northwest Iowa. However, radiation fog isn't typically the type of fog you expect to see with a fresh snowpack, especially with dewpoints in the single digits.

As we get into early Monday morning, we'll be looking at another shot of snowfall beginning in southwest Iowa by around 6 am and continuing over at least the southern half of the state for much of the day. This event won't be near the behemoth that moved through yesterday, lacking many of the forcing mechanisms that were in place over the weekend. The best band of frontogenetical forcing remains well to our south in Missouri, as does any low-level/WAA component of lift. Therefore, most of the snow will develop as a result of broad scale lift generated by the trough, as indicated by the stronger QG convergence in the 700mb to 500mb layer, most of which actually falls mostly at the top of abd above the dendritic growth zone. However, the DGZ will be fairly deep with cold vertical . profiles, suggesting snow-to-liquid ratios will be a bit higher than what we saw on Saturday. Cobb guidance is indicating SLRs in the 15:1 to 20:1 range, producing a fluffy and efficient snow. Will be interesting to see how these ratios are affected by lift above the DGZ rather than within it. The snow will also be falling intermittently through much of the day, which will allow for more residence time under the light to moderate snowfall. All this to say, we could very well pick up another 2 to 4 inches of snow over the southern half of the state on Monday, with some locations over 4 inches possible in southern Iowa. With this snowfall riding the coattails of yesterday's winter storm and this being the return to school/work for many after the thanksgiving holiday, have decided to issue a Winter Weather Advisory beginning Monday morning for portions of southern Iowa. Fortunately, winds will be fairly light as the snow moves through. Areas farther north into central and north central Iowa may also see snowfall, but will be less around an inch or less.

Snow wraps up on Monday evening with only token precipitation chances here and there through the remainder of the week. Cold temperatures then become the main story through the work week, especially on Wednesday into Thursday as a cold front brings colder temperatures down into the state. Overnight lows on Thursday night are forecast to fall below zero, with wind chills nearing the negative teens to near negative twenty on Thursday morning. Highs don't improve much on Thursday and wind chills stay in the single digits below zero. Temperatures then "warm" slightly into Friday as we get return flow on the backside of the high, but still remain cool through the weekend.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1138 AM CST Sun Nov 30 2025

MVFR stratus is beginning to give way to clear skies over northern Iowa, while central and southern IA remain broken to overcast around 1500 to 2000 ft. Brief flurries have been seen under this stratus, but impacts have been isolated and transient. There's still some uncertainty on if stratus will fill back in overnight, but it's likely there will be gaps in the deck leading to cigs fading in and out of MVFR. Have left fog mention in over the north overnight, given the signal for lower visibilities in guidance. That said, aside from light winds and low pressure, dry low levels may inhibit fog. Will continue to evaluate fog potential for tonight/Monday morning in future issuances.

Light snow will move into southern Iowa early Monday morning and persist through the day. This will likely impact KDSM and KOTM, although snow as far north as KFOD and KALO can't be ruled out. visibilities under 2 miles and ceilings around 1000 ft looks to accompany snowfall.

DMX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory from 9 AM to 9 PM CST Monday for IAZ074-075-084>086-095>097. Winter Weather Advisory from 5 AM to 6 PM CST Monday for IAZ083-092>094.