textproduct: Des Moines

KEY MESSAGES

- Scattered severe storms (Level 3 of 5) mainly across east- central Iowa this afternoon/evening. All severe weather hazards remain possible. More widespread storms and locally heavy rainfall expected tonight, especially over the southern half of Iowa.

- Additional rounds of severe storms and locally heavy rainfall still expected on Wednesday (eastern half of Iowa) and again on Friday (much of Iowa). Details on those events will be fine tuned in future days.

- Warm and breezy today through Friday with highs in the 70s and 80s. Much cooler readings in the 40s and 50s by this weekend, hard freeze likely north.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 251 AM CDT Tue Apr 14 2026

Day 2 of the active convective weather week, here we go:

Today...Highest Severe Threat: East-central Iowa.

Timing: Scattered activity late afternoon/evening, more widespread coverage overnight, especially south half of Iowa.

Persistent upper pattern remains locked in over the upper Midwest with a broad southwest flow aloft with several weak embedded shortwaves. As expected, the sfc low has shifted swd over KS/NE and will deepen slightly today with model consensus around 998mb by 00z Wed. The attendant sfc front will extend newd from the low across southeast NE, through central IA, and into the Great Lakes region. With the plume of anomalous low level moisture in place, moderate to strong instability, steep mid level lapse rates, and strong winds aloft /0-6km shear of 50-60kts/ would again support supercell development and all convective hazards should this parameter space be realized. The SPC Day 1 Outlook remains largely unchanged with an Enhanced Risk (Level 3 of 5) across east-central Iowa, with lower probabilities south/north.

Examining the latest guidance here are the key points worth mentioning and monitoring.

1) Capping - WAA in the 900-700mb layer will maintain the EML, with model soundings continuing to show moderate MLCIN. The question is whether low level convergence along the front and weak H5 height falls can provide enough lift to erode the cap and allow for CI. Some of the 00Z/14 CAMS struggle to initiate storms in the DMX area during the afternoon and evening, with storm coverage possibly higher in far eastern IA.

2) Some guidance /HRRR and RAP/ indicate a pseudo dryline feature pushing quickly eastward across central IA during the day dropping Tds into the 40s and 50s as far east as I-35. Other guidance /NAM, RRFS, ECMWF/ is not as aggressive with the dryline feature. Should this occur, the drier air could impact CI, storm mode and hazards - lesser TOR threat with higher LCLs.

Bottom line, now is not the time to let our guard down. The CAMs yesterday under did storm coverage, and this could happen again. We'll provide updates as the day unfolds and details become clearer.

Tonight...regardless of what happens during the day, there is higher confidence that a 40-50kt LLJ will restrengthen after 03Z tonight. This will result in strong moisture convergence and hence widespread convection over at least the southern half the CWA. Soundings indicate that these storms are likely to be elevated with the primary threats hail, perhaps wind if a cluster can organize, and locally heavy rainfall /20% to 40% chance of 1" or greater/. This will likely be a messy mode, with lots of storm interactions and mergers.

Wednesday...As noted in previous discussions, the convective evolution today and tonight will strongly influence what happens tomorrow, especially in term of warm sector recovery and position of frontal boundaries. What we do know is that another more potent upper shortwave will lift newd through the upper Midwest on Wednesday, inducing yet another sfc low to move through Iowa. Timing, position, and movement of the sfc features will be critical to the convective evolution. One camp of models has the sfc low moving more quickly ewd /e.g. NAM/ which could keep most activity east of this forecast area. The other global models tend to be slower with the evolution, which would move the sfc low and triple point through Iowa during peak heating. Should this occur, robust storm development, including supercells would again be possible, assuming sufficient destabilizaton. Again, specific details regarding the low level wind profiles, moisture content and LCLs, etc, will have an impact on the things like the tornado potential. The SPC has maintained the Slight Risk (Level 2 of 5) for now and agree that is reasonable pending the details noted above.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/

Issued at 251 AM CDT Tue Apr 14 2026

Will keep this discussion brief per the events above.

In the wake of Wednesday's system, a brief period of shortwave ridging should move into the region, yielding a "lull" in the action on Thursday.

This respite will be short lived however, as the strongest and most amplified upper trough/closed low moves towards the region on Friday. A broad, elongated sfc low developing over the High Plains will re-induce a strong southerly flow over Iowa with a warm and humid airmass surging back northward. Another round of severe storms is looking likely on Friday along strong cold front that will move quickly from west to east across the region. In fact, the SPC has increased severe probabilities to 30% on Day 4 for this reason, as clearly storm development will not be an issue with such a dynamic system.

As the storms and cold front move east of the state Friday night, colder air will wrap in behind the departing low and cannot rule out some snowflakes in northern portions of the state early Saturday. Temperatures will tumble into the 40s and 50s with breezy winds from the northwest on Saturday as well. As noted previously, we'll have to keep an eye out for a hard freeze on Saturday night, especially across northern Iowa.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 637 AM CDT Tue Apr 14 2026

Variable and challenging aviation conditions today. As in previous mornings, fog has developed at KFOD/KMCW with VSBYs bouncing as low as 1/4SM at times. Expect this fog will dissipate between 13-14Z. Also seeing pockets of MVFR status around the state, but its disorganized. Lower CIGs have remained in the vicinity of KDSM/KOTM, but have largely avoided the airfields. By later this AM, better mixing will yield a mostly VFR SCT/BKN deck around 4-5k feet. Still looking at the potential for scattered thunderstorms this afternoon, generally after 20-21z. Coverage looks relatively low through evening, so opted to keep the PROB30 for now until confidence increases. Later tonight, another round of showers and thunderstorms will develop associated with the LLJ, this could also result in periods of at least MVFR CIGs and VSBYs. Winds today will favor a southerly direction in the south, with variable or northerly winds at KALO/KFOD/KMCW.

HYDROLOGY

Issued at 239 PM CDT Mon Apr 13 2026

Multiple rounds of seasonally moderate to heavy rain this week will lead to renewed flooding concerns. Presently the main concern will be possible renewed or additional river flooding.

Output from the GFS- and NBM-forced medium-range National Water Model (NWM) and the Hydrologic Ensemble Forecast System (HEFS) suggest the most likely scenario will be moderate to significant within-bank rises on many rivers and streams, especially across the southeast half of the CWA over the next week. A few locations may see minor river flooding as well. These rises will be due to the additive effect of multiple rounds of rainfall. If rainfall is higher than presently forecast then the risk of several locations seeing minor flooding and a few locations seeing moderate flooding will increase.

Flash flooding is less of a concern than river flooding, however the risk is nonzero. The most likely scenario will be ponding of water or low-end flash flooding especially in urban areas or areas that receive repeated heavy rainfall over a relatively short time period.

DMX WATCHES/WARNINGS/ADVISORIES

None.