textproduct: Des Moines

KEY MESSAGES

- Warmer today but clouds will have an impact. Perhaps a few sprinkles.

- A band of snow expected late Wednesday and Wednesday night. PoPs remain more broadbrushed than what will occur as the snow accumulations will be in a more focused area. That area will be refined with upcoming forecasts.

- Existing and possible new snow cover will impact Friday temperature forecast. The snow could be a significant impact. Temperatures do look to trend lower this weekend.

UPDATE

Issued at 403 AM CST Tue Feb 24 2026

Rising temperatures are occurring over Iowa early this morning as southerly flow has returned to the state with high pressure moving to the east and a system approaching from the west. An upper level system will pass across Minnesota and Wisconsin today. The thermal ridge will move across Iowa ahead of this system before being suppressed south by the short wave this afternoon. Still evaluating precipitation chances as this system passes through the region. The is good forcing above 10 kft for hydrometeor production but there will be a vast amount of dry air to overcome sub cloud base. A few sprinkles could reach the surface, especially if cloud bases can get down to 6 kft, but at this time, that does not appear likely so have maintained a dry forecast. High temperatures today are the other challenge as the thermal ridge moves across the area. The mid-level moisture transport is originating from the Pacific and will be moving across Iowa today and is in part responsible for the cloud cover today along with the short wave. The clouds will present most of today and will be opaque and efficient at solar filtering. Continue to lower high temperatures but probably remain too warm for much of the area. Again, coolest temperatures will be over the snow pack.

The other primary forecast challenge this period is the potential for precipitation Wednesday afternoon and night. As alluded to last night, the main upper level short wave energy will be passing well south of Iowa. Precipitation chances in Iowa will hinge on moisture overrunning the state and isentropic vertical ascent along with the surface high pressure to the north. With the main upper level energy to the south, the surface system will also be south and that will cutoff Gulf moisture from streaming northward so will again be placing much of the saturation workload on the Pacific moisture stream mentioned above. Reviewing deterministic data for the placement of the isentropic ascent yields a hodgepodge of solutions with the NAM continuing to be the furthest north. This hodgepodge of solutions also results in a NBM solution that is much too broad with precipitation chances, especially north where dry air originating from the high pressure to the north will have an impact on the north edge. Favor solutions that place a more narrow area of snow from northwest to southeast through central Iowa where a clustering of solutions place the peak isentropic lift and far enough away from high pressure/dry air impacts. Expect this band to produce 1 to 4 inches of snow and based on peak lift through the dendritic layer, there may be a brief period of 1 inch per hour snowfall rates. Despite honing in on an expected area for this band to occur, more detail and resolution will be needed over the next 24-36 hrs to determine the exact of the thermal dynamic profile of this system which may require adjusting this band. Note the QPF in the forecast this morning is focused too far north and thus the current forecast is likely too far north as well for collaboration purposes at this point. Expect that to change.

DISCUSSION

Issued at 156 PM CST Mon Feb 23 2026

The weather over Iowa today is tranquil with surface high pressure passing through the region with a Nor'easter raging near the 40/70 benchmark and a ridge over the western US. There are a few mid and high level clouds over the state with a more expansive area just to the west over Nebraska. At the moment, however, a clear sky that allows great viewing of the swath of snow over the state from southwest to northeast. This snow area poses great challenges to the temperatures forecast, especially late this week, that will be detailed below. As the surface high pressure slides to the east this afternoon, our low level flow will become from the south and later southwest before a cold front pushes through the state later on Tuesday. Warm air advection will precede the front along with plenty of mid and high level clouds. Temperatures will push well into the 40s in the snow free areas and perhaps low 50s along the Missouri border. For areas that have snow on the ground, temperatures will be lower than the initial National Blend of Models (NBM) and have blended in 25th percentile NBM to account for the snow. The front that will move through the state will be associated with a shortwave trough and surface low tracking along the US/Canada border into the Great Lakes. Most of the precipitation is forecast to fall north of Iowa where there will be stronger forcing closer to the low. However, cross sections show saturation aloft reaching far northern Iowa, which is trying to work its way down to the surface Tuesday afternoon. The saturation is rather fleeting and the degree of dry air in the sub-cloud layer results in a continued dry forecast.

The shortwave passing on Tuesday will aid in developing a broad, low amplitude trough over the Great Lakes and Ohio Valley while at the same time sheared out energy topping the ridge will flow into this developing trough. The track of this energy, which right now looks to be through Nebraska/Kansas into the Ozarks, should bring accumulating snow and rain into some portion of the state as moisture overruns the now stalled out front well south of Iowa. The placement of this precipitation varies greatly over the state with model trends not lending confidence to one solution over another. Timing wise, precipitation looks to arrive later Wednesday over central Iowa exiting by sunrise Thursday. Beyond Thursday, temperatures on Friday are too high from the initial NBM in the areas that have or will have snow. This is partially a result of models being too warm earlier in the week, which results in more melting of the snow pack than what will likely be reality and thus allows for more warming vs energy devoted to melting snowpack. In addition, there will be new snow that falls Wednesday/Wednesday night with placement issues already discussed that will temper the warmth. As another cold front surges through the region late this week or early this weekend, temperatures will trend toward seasonal levels. While moisture may be limited this weekend, there is a signal for snow with phased thermodynamic and kinematic forcing in the area. The southern edge of this system may have a period of rain or even brief freezing rain before transitioning to snow.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 539 AM CST Tue Feb 24 2026

Mid-level clouds will increase and lower to 8-10 kft today and will remain VFR. The forecast is focused on a wind shift and a few periods with gusts as a boundary moves across the state today. The wind will be northwest and diminish below 10kts tonight.

DMX WATCHES/WARNINGS/ADVISORIES

None.