FXUS63 KDMX 122036 AFDDMX Area Forecast Discussion National Weather Service Des Moines IA 236 PM CST Fri Dec 12 2025 .KEY MESSAGES... - Winter Weather Advisory for 1 to 4" of snow Saturday. Locally higher amounts possible. - Cold Weather Advisory follows Saturday night and Sunday morning. Wind chills as low as -30 expected north. - Mild weather builds in the first half of the work week. && .DISCUSSION... Issued at 229 PM CST Fri Dec 12 2025 A thermal front has moved across the state today and temperatures were starting to slide into the teens in northwest Iowa. Precipitation was sparse along the front, with most of it closer to the parent low to the northeast of the state. Midlevel cloudiness will replace the low level stratus at least for a time tonight. The last gasp of energy along the northwest flow pattern arrives tonight. A notable change has been a warming of the midlevels compared to yesterday, taking some of the profile out of the DGZ. This is due to the strong downslope flow with wind speeds up to around 70kts. This reduces the SLRs below 20:1, increasing confidence in snowfall amounts remaining under 4 inches for much of the Advisory area. There will be locally higher amounts embedded as the weak fgen band generates lift in the DGZ. Omega values generally remain below -5, but midlevel Q vectors intensify as the clipper reaches southeast Iowa, increasing synoptic forcing. Some ice pellets could mix in on the southwest flank of the snow as ice introduction aloft is lost, but the drops will fall towards the cold low-levels, causing freezing before they reach the surface. Temperatures plummet as clouds are pulled away and an arctic high approaches. Cold northwest flow will drop temperatures below zero statewide. There will be a window of wind chills as low as -30 degrees in the north, the window for this being short due to the high settling overhead, calming winds. A Cold Weather Advisory was issued for Saturday night/Sunday morning to reflect when these dangerous wind chill values will occur. An upper level ridge will break this stagnant northwest flow pattern in the early week. Temperatures over 40 degrees will work to erode the snowpack. Flow will switch to zonal during the second half of the week which will open up the chance for a more active pattern with the Pacific moisture in play. && .AVIATION /18Z TAFS THROUGH 18Z SATURDAY/... Issued at 1143 AM CST Fri Dec 12 2025 Patchy IFR cigs impacting all sites at times over the next 3 hours, then becoming MVFR through 00z or shortly after. For snow timing tomorrow, FM groups are similar to yesterday's snow, adding in a Prob30 for lower vsby restrictions for KDSM and KOTM where lower vsbys are possible from heavier snow. With the snow MVFR/IFR cigs possible. && .DMX WATCHES/WARNINGS/ADVISORIES... Cold Weather Advisory from 6 PM Saturday to 10 AM CST Sunday for IAZ004>007-015>017-023>028-033>039-045>050-059>062-073>075- 084>086-095>097. Winter Weather Advisory from midnight tonight to 3 PM CST Saturday for IAZ023-033>036-044>048-058>060. Winter Weather Advisory from 3 AM to 3 PM CST Saturday for IAZ049-061-062-073>075-085-086-097. && $$ DISCUSSION...Jimenez AVIATION...Jimenez