textproduct: Des Moines

KEY MESSAGES

- More showers and thunderstorms are expected through the day today. There is a low chance of a few brief tornadoes, mainly across portions of southern Iowa through this afternoon.

- Light rain chances will linger from tonight through Thursday. Notably cooler weather is also forecast from Wednesday through Friday, with daily highs generally in the upper 40s to mid 50s on those days.

- Drier weather returns from Friday through early next week, along with a slow warming trend over the weekend.

SHORT TERM /THROUGH TONIGHT/

Issued at 131 AM CST Tue Nov 3 2026

A broad and deep trough will slowly cross the region today. Currently, the 500 MB trough axis extends from the Red River of the North down across Nebraska and into western Kansas where a closed 500 MB low is centered. At the surface, there are two low pressure centers anchoring the ends of the trough - one near the arrowhead of northern Minnesota and the other on the Oklahoma/Kansas border. The surface front extending between these lows has entered far northwestern Iowa early this morning, and will reach central Iowa by early this afternoon. Meanwhile, the southern low will swing northeastward during the day and across our service area tonight.

Currently, within the broad area of lift along the leading flank of the southern low, a broad swath of showers and thunderstorms is moving north northeastward across much of eastern Nebraska, southern and central Iowa, western Missouri, and Kansas. Earlier, on Monday evening, there were sporadic severe weather reports from a few of these storms in eastern Kansas, however they have since diminished in overall intensity. As the storms percolate across our area early this morning the severe weather risk will be low overall, however, as we have discussed for the previous couple days there is a very low chance of a brief tornado or two, mainly in southern Iowa. Low-level shear profiles/hodographs are very favorable in that region, however, the thermodynamic environment is marginal in the form of weak lapse rates, a mostly saturated profile, and a weak near-surface inversion.

The bulk of the early morning convection will clear our forecast area by around or just after sunrise, followed by a relative lull in the mid/late morning during which more widely scattered, that is to say less numerous/widespread, showers and storms may occur. During this time, the nearly stacked cyclone approaching from the south will move over northern Missouri and toward southern Iowa, preceded by some limited breaks in the clouds and resulting in rapid low-level destabilization. By 18Z a pool of strong 0-3 KM AGL CAPE in the 250-350 J/KG range will develop across this region, with a ribbon of enhanced surface vorticity and stretching potential extending up along and just ahead of the surface front into southern/eastern portions of our forecast area. It is expected that an arching cluster of storms will move through carrying an attendant threat for isolated tornadoes given the strength of both the low-level thermodynamic environment and the continued strong near-surface shear profiles ahead of the low and near the boundary. There are some mitigating factors however, which is why SPC is advertising "only" a Marginal Risk for severe weather in our southeast. For one thing, while the near-surface instability is quite strong, overall instability is relatively limited with SBCAPE of around 1000 J/KG and a deeply saturated profile. Low-level lapse rates are progged to be better than on Monday, but still modest around 6.5-7.0 C/KM. Also, low-level speed shear remains impressive but direction shear is not as impressive as during the preceding periods, with a distinctly less curved and more straight hodograph. Even so, any local backing of near- surface winds ahead of the approaching low could enhance the tornado potential and this threat is something we will be closely monitoring through this afternoon.

By late in the day today and toward this evening, the low will sit right over our area resulting in a continuation of rain showers but with less instability/thunderstorm potential. Winds will gradually turn around to northwesterly by late tonight and begin to increase as the low begins to move up into Wisconsin by sunrise Wednesday.

LONG TERM /WEDNESDAY THROUGH MONDAY/

Issued at 131 AM CST Tue Nov 3 2026

On Wednesday and Wednesday night the stacked cyclone will continue to move away from our area, across Wisconsin and up to around Lake Superior. A large cloud/light rain shield wrapping around its backside will pivot across Iowa during this time, especially the northern half or so of the state, and generally make for gray and blustery conditions with areas of light rainfall. These conditions will persist from Wednesday right through Thursday, with high temperatures on both days ranging only in the upper 40s north to mid/upper 50s southeast; notably cooler than we have seen in the last couple of weeks or so.

From Friday onward the forecast is much more quiet and dry as we enter a period of west northwesterly 500 MB steering flow with periods of modest ridging therein. No rain is forecast during this time, and while Friday highs will remain cool in the upper 40s/50s once again, a slow warming trend will then bring them up into the upper 50s/lower 60s by next Monday. This will make for a very pleasant, if slightly cool, late autumn weekend across the region.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 520 AM CST Tue Nov 3 2026

Low IFR ceilings will prevail for much of the TAF period, except for a period of relative clearing this afternoon into evening mainly at DSM/OTM where MVFR or briefly VFR conditions may return. In addition, periods of SHRA/TSRA remain likely mainly early this morning and again around late afternoon. Have attempted to time these periods in the 12Z TAFs, but amendments are likely through the day.

DMX WATCHES/WARNINGS/ADVISORIES

None.