textproduct: Des Moines

KEY MESSAGES

- Lingering convection over far southern Iowa early this morning then drier the rest of today through the daytime Monday.

- Fog is possible early this morning.

- Strong storms and potentially heavy rainfall is possible Tuesday/Tuesday night.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 253 AM CDT Sun Aug 16 2026

Patchy to areas of fog have developed this morning but thus far, the fog has been mostly transient over central Iowa with lower visibilities not sustaining. Drier air is finally beginning to filter south into Iowa early this morning as a broad areas of high pressure is moving into the Upper Midwest. The switch to northerly wind and lowering dew points should help diminish any fog over northern Iowa early this morning. Deeper moisture and the 2+ inch PWATs remain over far southern Iowa while the main surface warm front continues to retreat south and deeper into central Missouri. Thunderstorms are ongoing over northern Missouri but the main focus this morning is the complex of storms lifting northeast out of north central Kansas. This complex is lifting northeast along the MUCAPE axis, which still extends north into southern Iowa. As the complex moves northeast, the MUCAPE axis will settle slowly south, but will remain long enough for some of the convection to reach the far southern Iowa in a weakened state. High pressure will continue to settle into Iowa today resulting in less humid conditions and drier conditions. Those drier conditions will persist into much of Monday, however, return flow on the back side of the high pressure and an approaching boundary will bring renewed thunderstorm chances to northern Iowa by Monday evening and night. High temperatures today and Monday will be pleasant and in the upper 70s to low 80s.

LONG TERM /TUESDAY THROUGH SATURDAY/

Issued at 246 PM CDT Sat Aug 15 2026

Shower and thunderstorm potential returns area-wide again Tuesday into Wednesday. Given this will be another northwest flow regime, it's tough to get too involved in the details. That said, the Tuesday storms do seem to have a rather healthy environment with increasing instability and modest deep layer shear supportive of more organized convection. SPC does have a day 4 15% risk for most of Iowa and WPC has put out a slight risk for excessive rainfall for Tuesday. The pattern remains relatively active through mid- week and then ridging begins to build through the second half of this week.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1110 PM CDT Sat Aug 15 2026

Main aviation challenges will be low ceilings overnight and patchy fog development. Most sites will see some degree of MVFR or low end VFR ceilings before these lift or scatter into VFR by mid morning. In addition, recent rainfall and light winds may allow patchy light fog to develop, especially at ALO and OTM with MVFR restrictions shown. Winds from the north-northwest will be increasing towards 10 knots around sunrise over northern Iowa, which may limit the fog potential in these locations. Those winds from the north-northwest will reach 8 to 12 knots around midday with VFR conditions prevailing through the end of the period.

DMX WATCHES/WARNINGS/ADVISORIES

None.