textproduct: Des Moines

KEY MESSAGES

- Near record to record warmth persists into Monday.

- Low chances for precipitation far south Monday night. Greater chances central and south late Tuesday/Tuesday night. A strong storm may occur.

- Greater chances for widespread precipitation Wednesday night and Thursday.

- Much cooler end of the week and into next weekend.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 217 PM CDT Sun Oct 11 2026

Persistent southwest flow at the surface has remained over Iowa today. Dew points have been increasing this afternoon as the remnants of Isaias continues to move northeast towards the Atlantic seaboard and surface high pressure has developed over southern Mississippi and Louisiana. This has led to developing return flow of Gulf moisture and the increasing dew points. Deeper layer theta-e advection has been ongoing as well but there is little evidence this has been occurring regarding clouds outside some cumulus development to the south across eastern Oklahoma and Texas. Further west, the remnants of Hurricane Rachel has brought strong winds and heavy rainfall to the Desert Southwest. Yet another feature is the closed upper low pressure dropping south from the Pacific Northwest. This upper low along with building sub-tropical high over the lower Mississippi Valley, will amplify the southwest flow into Iowa through mid-week. This flow will initially push the remnant of Rachel into the far Northern Plains on Monday, leaving Iowa mostly dry outside of a low precipitation chance south Monday night.

Temperature wise, a few sites will reach record high today and at the time of this discussion, Mason City has already tied a record high for this date. Record warm low temperatures are possible/likely for Monday and will hinge on timing of a weak cold front moving through Monday night. For most locations that boundary passage will be near to after 06z and shouldn't impact the low temperatures. The record warm low temperature for Des Moines on Monday (Oct 12th) is 66 degrees. The current forecast 24 hr low for Monday at DSM is 71. Record high temperatures for Monday are several degrees higher than today's records and in the upper 80s to mid 90s.

LONG TERM /TUESDAY THROUGH SATURDAY/

Issued at 217 PM CDT Sun Oct 11 2026

The shallow surface boundary will stall somewhere across northern Missouri on Tuesday and favor the more northern solutions for this boundary location given the west/southwest flow aloft and how shallow the feature is. Moisture will overrun this boundary and will bring increasing chances for showers and storms to parts of central and southern Iowa. MUCAPE values may approach 1000 J/kg over far southern Iowa. This does look possible and should saturation occur near 800-850 mb, lapse rate above this level are sufficient for this MUCAPEs and could support marginally large hail. The greater chance for showers and storms arrive Wednesday night into Thursday as the main upper low lifts northeast into the region. A strong system diving south out of Canada will quickly push the precipitation out of the area. Much cooler temperatures will follow with highs in the 50s and 60s and overnight lows in the 30s along with the potential for frost perhaps as early as Friday night.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1237 PM CDT Sun Oct 11 2026

Aviation forecast remains focused on wind gust and low level wind shear timing. Gusty south winds this afternoon will diminish around 23z. LLWS is expected to develop at most sites tonight as the low level inversion sets up. The LLWS will diminish from north to south overnight as the stronger winds off the sfc diminish. Otherwise VFR conditions will persist.

DMX WATCHES/WARNINGS/ADVISORIES

None.