textproduct: Des Moines

KEY MESSAGES

- Severe storms very late this afternoon into this evening. Large hail and damaging wind gusts along with a few tornadoes are all possible.

- Freezing rain potential remains in our far northwest forecast area late tonight into the pre-dawn hours of Saturday. Winter Weather Advisory in Emmet County with potential impacts also affecting far northern Palo Alto or Kossuth County, though uncertainty remains.

- Breezy and cooler Saturday followed by breezy and warmer on Sunday. Elevated fire weather concerns may develop on Sunday as well given the warm, breezy, and drier airmass.

- Next chance for rain and storms is later Tuesday into Tuesday night.

SHORT TERM /THROUGH TONIGHT/

Issued at 247 PM CST Fri Mar 6 2026

Although showers or storms festered through much of this morning, clearing and some sunshine has peaked through this afternoon in especially southwest Iowa which favors the clearing scenario presented in the previous discussion.

Latest midday analysis has the strong cold front already into far western/northwestern Iowa with gusty northwest winds and cold temperatures in the 30s behind. Meanwhile, the warm front has been lifting into central Iowa and is still expected to lift towards around the Hwy 20 corridor or so through the rest of this afternoon. In the warm sector, temperatures have climbed into the 60s to low 70s with dew points in the upper 50s to 60s as well. Ample moisture continues to flow into the state ahead of the elongated surface low nudging into western Iowa this afternoon and SPC Mesoanalysis shows 1000 J/kg of uncapped MLCAPE nudging into southwest Iowa already as of 20Z paired with 40-50 knots of effective shear. Although bubbling cu and related showery radar returns have started to develop early this afternoon, still generally expecting the storm threat to increase/ramp up as the better synoptic support arrives later this afternoon/early this evening. Forecast soundings still show strong deep layer shear with a strong jet nudging into the area with instability still forecast to increase over the next few hours as well. Storms will likely develop in the west/southwest with surface based severe potential very much in play as storms develop. There is still good consensus of storms growing upscale which will start to lessen the tornado threat as updrafts compete with one another but prior to that if any additional backing can occur, this would increase the low level hodograph curvature from the largely unidirectional seen in many forecast soundings. Large hail and damaging wind gusts also remain in play with the largest hail most likely in any initial supercells. As storms grow upscale, cannot completely rule out QLCS potential with sufficient 0-3km shear especially if the storms can take on a bowing structure with otherwise the shear vectors largely in line with the front. Any storms that can remain isolated out ahead of the line may also pose a tornado threat. In summary, still expecting severe storms to develop late this afternoon (early evening) and persist well into the evening in potentially multiple waves as storms develop and move southwest to east northeast across the area. The Enhanced Risk (Level 3 of 5) by the SPC remains well placed and folks in much of southern to central Iowa should make sure they have multiple ways to receive warnings tonight!

See the hydro section below for information on any hydro concerns.

Behind the storms which finally move out of the area near to just after midnight tonight, the deformation zone brings wrap-around precipitation to portions of southern Minnesota into northwest Iowa. With the cold front trending faster, the amount of time for freezing rain/drizzle potential has increased in forecast soundings in far northwest Iowa compared to this time yesterday. Models continue to vary in amount of ice accumulations which is likely due to continued concerns in icing efficiency with warm ground temperatures today, wet surfaces which would then have to cool, and soil temperatures also above freezing. Forecast soundings largely suggest freezing rain/drizzle to be the predominant precipitation type with a warm nose aloft, though a few have shown ice introduction at times while the profile is cool which could bring in a burst or so of snow. Not really expecting much in the way of snow based on limited agreement of ice introduction paired with lift still present, and profiles cool enough to support snow. Icing amounts of up to around of a tenth of an inch continued to be supported in Emmet county, but it is unlikely all of this icing potential will be realized. Have gone ahead and issued a Winter Weather Advisory for any potential freezing rain icing impacts in Emmet county with impacts most likely on elevated surfaces like bridges or trees and much more delayed on roadways given the concerns noted above. These impacts could potentially clip the far northern portions of Palo Alto or Kossuth county but with the limited area of impacts in those counties at this point, kept the Winter Weather Advisory out of those areas. Will certainly continue to monitor conditions tonight into early Saturday morning.

LONG TERM /SATURDAY THROUGH THURSDAY/

Issued at 130 AM CST Fri Mar 6 2026

Behind the aforementioned cold front, breezy winds from the northwest averaging 10 to 20 mph will deliver drier and cooler, more seasonable air. This cooler airmass will not last long as winds become from the southwest at 10 to 20 mph on Sunday returning the warmth with highs well into the 60s. With the warm, windy conditions, fully cured fuels, and relative humidity values in the afternoon falling to between 30 and 40%, elevated fire weather concerns may materialize. Winds will be not as strong on Monday and may mitigate fire weather concerns with similar conditions otherwise as low pressure tracking over southern Canada sends a cold front into the state with uncertainty in its placement. Initial National Blend of Models (NBM) shows this uncertainty in its temperature forecast with 25th-75th spreads of 20 degrees and run to run inconsistency in its deterministic forecast. While it is still confident to say that temperatures will be above normal, how much will be the question on Monday and Tuesday. As the Baja closed low opens up into the southern Plains late Tuesday, the northern stream trough will begin to push southward towards Iowa. There does look to be theta-e advection ahead of these features that will lift the stalled front back into some portion of the state and bring a chance for showers and storm. Depending on the location of the boundary, there may be appreciable instability and shear for stronger storms in southern or southeastern Iowa with this supported by the AI/ML convective hazard forecasts as well. As the northern stream trough pushes this all out of Iowa Wednesday, should see cooler, but still above normal temperatures somewhere in or around the 50s through the end of the week.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1154 AM CST Fri Mar 6 2026

Challenging aviation forecast through the rest of the day into tonight. IFR to LIFR ceilings under low stratus in northwest Iowa as a cold front approaches, while much of the rest of the area is still in the warm sector with some clearing beginning to occur in the southwest behind the lingering early day activity in the east. Thunderstorms are still forecast to develop in the west late this afternoon before expanding east northeast through the rest of the evening. Some of these storms still have the potential to be strong to severe and will address any localized severe weather impacts in short-term updates. Have otherwise tried to address most likely periods of showers and storms, but expect updates as storms develop and exact track is better understood. Behind the showers/storms low stratus will keep or drop ceilings to IFR or lower into early Saturday morning with winds sharply changing direction and increasing out of the northwest.

HYDROLOGY

Issued at 247 PM CST Fri Mar 6 2026

Flash flooding and river flooding are the short term and longer term concerns due to both the QPE from last night's storms into this morning as well as QPF through tonight.

QPE from last night's storms into this morning was seasonally moderate to heavy. Nearly the entire CWA received at least 0.75 to 1 inch of rain with some locations 2+ inches. A small area of 3+ inches fell across the southwest CWA. This rainfall quickly increased top-layer soil moisture. FLASH CREST and SAC-SMA data shows at 40-50% across a large portion of the west central into northeast CWA. Flash flood concern increases significantly when those values reach at least 40-50%. Some recovery is expected however it will likely not be significant by when the rain falls later today. Another factor is ground frost. Soil temperature data from University of Iowa and Iowa State University soil monitoring networks suggest at least scattered top layer ground frost exists especially from US 30 northward. This frost would slow or not allow water infiltration, which would increase runoff into streams. Short range NWM suggests flash flooding is possible as well. The most likely scenario will be ponding especially in urban areas with some lower-end flash flooding possible this evening and early tonight.

In terms of river flooding, many streams began rising in response to runoff from the rain last night into this morning. The QPF through tonight will lead to more response. Nudged our official river forecasts down at many locations because the model appeared to over- simulate the responses in spite of decent QPE and QPF. The short- range and medium-range NWM flow AEPs tend to support the downward adjustment. They call for significant within-bank rises on many streams, but only a few locations possibly reaching flood stage.

DMX WATCHES/WARNINGS/ADVISORIES

Winter Weather Advisory from 9 PM this evening to 9 AM CST Saturday for IAZ004.