textproduct: Kansas City/Pleasant Hill

KEY MESSAGES

* Cooler conditions continue through the end of the workweek, with rainfall chances arriving as soon as Thursday morning (10-30%). The greatest chance for rain is overnight Thursday through Friday morning (70-80%).

* Low-end chances (20-30%) for rain extend into the weekend with temperatures creeping into the upper 70s and lower 80s.

DISCUSSION

Issued at 424 AM CDT Wed May 20 2026

A loop of the latest H5 analyses depicts the unwavering nature of the upper-level trough out west. While this system was enjoying its West Coast vacation, lee cyclogenesis has begun in northern British Columbia and Alberta as a 130+ kt jet streak runs over the Northern Rockies. Over the next 24 hours, this process will produce two distinct mid-level cyclones. One is expected to hold north along the U.S./Canada border while the other is pulled south by the upper- level jet. The latter's influence may be felt as early as Thursday as it ejects a series of shortwaves into the region. Guidance suggests the first shortwave could move through as early as midnight on Thursday. However, dry air aloft will limit rain potential for at least several more hours. There are some indications that mid-level moisture could improve as soon as Thursday morning, but this comes many hours after the subtle vort max passes by. Rain is not out of the question during the earlier portions of the day on Thursday, but it will be reliant on the timing of saturation aloft relative to that of the shortwave. Given these conditional circumstances, hourly PoPs have been limited to 10-30% between 06Z and 18Z Thursday. Increasingly southerly mid and low-level flow throughout the afternoon and evening on Thursday will bolster rain chances as a second shortwave is introduced to the region. The coincident timing of the shortwave and moisture increases confidence in precipitation late Thursday afternoon through early Friday morning, with the greatest 6-hourly PoPs (70-80%) occurring overnight and early Friday morning.

As the mid-level low dives south along the Rocky Mountain range, lee cyclogenesis looks to be induced yet again with a small lee cyclone appearing just east of the New Mexico border as early as Friday morning. Although rainfall chances should generally decline throughout the day on Friday, the primary cyclone is outlooked to bend northeastward through Nebraska and northwest Iowa late in the day leading to increased low-level south/southwesterly flow, so WAA induced showers remain a possibility. Some weak to modest instability may be able to develop in the southern fringes of the CWA, but shear looks to remain poor. Regardless, a rogue elevated and sub-severe storm cannot be ruled out Friday evening.

Increased WAA courtesy of the primary mid-level low will help boost temperatures into the lower 70s and upper 80s heading into the weekend. By Saturday morning, the mid-level lee cyclone is expected to arrive. Ample uncertainty remains on the type of impact this system could have locally as current projections keep the surface cyclone and boundary near the southern and eastern fringes of the CWA. Should the placement be further north, shower and storm chances would increase with more opportunities for ascent at the ready. Modest instability also looks to exist south of the surface boundary, so a further northward progression could open the door for some degree of convective development Saturday afternoon. Like Friday evening, though, shear profiles remain unimpressive. A day to keep an eye on, but nothing to write home about for now.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 502 AM CDT Wed May 20 2026

SCT low/mid level clouds to continue pushing off to the east, making way for FEW high clouds for the remainder of the day on Wednesday with winds 5-10 kts out of the ENE. Overnight, expect clouds to build back in to BKN with CIGs dropping to roughly 5000 ft. A few sprinkles may be noted in the last couple hours of the TAF period, but prevailing -RA/-SHRA is not expected until several hours beyond the end of the current TAF period.

EAX WATCHES/WARNINGS/ADVISORIES

MO...None. KS...None.