textproduct: Des Moines

KEY MESSAGES

- Gusty winds persist this afternoon and evening, diminishing overnight.

- Mild and quiet conditions Thursday

- Light rain chances Friday into Saturday, then mild through the remainder of the weekend.

DISCUSSION

Issued at 254 PM CDT Wed Apr 2 2025

Skies have cleared out nicely behind the morning showers and storms, allowing temperatures to warm nicely ahead of the low pressure passing overhead. This has resulted in cumulus development throughout the area. Similarly, a few of these rising parcels have taken advantage of a shallow layer of instability within the warm sector, resulting in isolated thunderstorms. The instability has been quite low (~500 J/kg), but have seen some healthier updrafts thanks to the strong shear through the unstable layer and even a splitting updraft, as was suggested by the long straight hodographs. That all said, the low CAPE/high shear setup has proved detrimental to the storms longevity, as the strong wind fields shear apart the storms. As of this writing, no reports have been sent with any storms, with the storm chances diminishing through the next hour or so as the low and associated boundary continue east through the area.

In addition to the cumulus and isolated storms, the subsidence being created by cold air advection and the tightening pressure gradients around the low, have resulted in strong wind gusts throughout central Iowa, with multiple observed gusts of 45 to 55+ mph. These winds have been strongest along the boundary, but will likely still see breezy winds through much of the afternoon and evening as the low continues eastward. The Wind Advisory remains in effect until 7 pm, but will likely begin to cancel counties from west to east as the wind threat diminishes behind the boundary.

After the departure of the low pressure system, conditions quiet down through Thursday as surface high pressure fills in. This will result in light winds, mild temperatures and partly cloudy skies with increasing cloud cover through the afternoon and evening hours on Thursday. As we get into Thursday night and Friday, another upper level wave will drop south out of Canada and meet with the upper level ridging to our southeast. This interaction of upper troughing to the north and ridging to the south will be responsible for multiple days of severe weather and heavy rainfall for those in the Ohio River valley region. Fortunately for us, we will be displaced to the northwest of the axis of heavy rainfall and storms, but will still see some showers and occasional thunder sneak into Iowa on the far northern periphery of the system to our southeast. Likewise, ahead of the approaching upper level wave to our north, additional rain chances will develop over northwest Iowa Friday. Neither of these rain chances (north or south) will be overly robust, given the main moisture stream will be to our south and east. Precipitation chances in the northwest linger into Friday night, and could even see a brief switch to a rain/snow mix in the far northwest before ending early Saturday morning. Precipitation chances with the southern system look to linger a bit longer into Saturday, but will eventually drift south out of the state through the afternoon.

In addition to precipitation chances, another shot of cool air will funnel into the state with the aforementioned upper level wave, keeping temperatures mild in the 50s through the remainder of the weekend. As we move into late Sunday and Monday, yet another reinforcing wave will eject through the overall troughing pattern to our north, bringing another push of cooler air on Monday, keeping temperatures in the 40s. While no precipitation chances are in the forecast at this time, the 12z GFS has started to produce light QPF over the northeastern half of Iowa late Sunday night into Monday. The main gulf moisture stream will still be off with the ridging to our southeast, meaning any moisture would likely have to be sourced from the pacific stream. This doesnt mean that precipitation is impossible, but the profile may struggle to saturate without sufficient moisture transport. This is evident in the rest of the deterministic guidance, which only depict spotty QPF with this wave, keeping most of our area dry. Regardless, will be something to watch through the coming days. Beyond Monday, upper ridging builds in from our west and temperatures begin to climb again through the middle of next week.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1155 PM CDT Wed Apr 2 2025

MVFR stratus will linger near northern terminals in the short term, gradually lifting to VFR before 18z. Gusty westerly winds will ease after 12z and become variable to northeasterly after 20z.

DMX WATCHES/WARNINGS/ADVISORIES

None.