textproduct: Omaha/Valley

KEY MESSAGES

- Heavy rain and flash flooding will be the main concern from late afternoon through the overnight hours. One to two inch rainfall totals with isolated totals three to five inches.

- Slight to enhanced risk of severe thunderstorms late this afternoon into the late evening. Damaging winds and large hail are the primary threats.

- There will be a pleasantly mild temperatures for the first full week of summer. High temperatures in the 70s and low temperatures in the 50s are expected.

DISCUSSION

Issued at 228 PM CDT Sat Jun 20 2026

Ongoing area of showers with embeded thunderstorms moving into the western part of the forecast area early this afternoon. Increasing moisture transport and increasing large scale ascent aiding in the precipitation development along and east of MU- CAPE gradient located across the area. Meso-scale models have been poor in handling overall evolution, with previous 06z ARW cores being the closest to what's current going on. Upper level disturbance overtopping southern Rockies ridge axis will allow precipitation to continue to evolve, as low level thermodynamics sync and increase surface-mid level moisture transport. Better surface-based instability appears to remain further south into Kansas, with some intrusion into southern Nebraska. Better kinematics associated with best SB- and MU-CAPE look to occur west of the area. However, there will be a brief period from 23z-04z in which there may be just enough mid-level instability and mid- level shear to produce large hail and damaging winds, west of an BVN to BIE line.

Heavy rainfall is expected in two areas. An area of along warm- front and north of a warm front that will lift to about the Kansas- Nebraska line by 00z, then as the upper disturbance traverses the area between 03z and 09z, H9-H8 frontogensis generally along an OLU- OMA-RDK line develops. With sustain moisture transport, the severe threat will diminish but heavy rainfall will become the primary threat. Operational GFS and EC both highlight 50-90% probabilit of 6-hr rainfall above 100-year ARI at 06z and 12z. The NAEFS and ECENS are less bullish, with probabilies 30-40%. Forecast precipitatable water values are 80-99% of climatological normals, and with warm-rain processes becoming dominate, cannot discount widespread 1-3 inch rains with extreme shift-of-tails rainfall amounts three-five inches.

Sunday through Friday...

Though there will be showers and isolated storms ongoing daybreak Sunday, expected activity to move east of the area by mid-day. with clearing condiitons. Synoptic models attempt to redevelop showers across northeast Nebraska Sunday afternoon/evening due to syncing of cyclonic conveyor of upstream H5 disturbance and anti-cyclonic conveyor of downstream disturbance. Left low PoP generated by NBM. Otherwise, forecast looks "dry" through Tuesday when another more potent shortwave dives out of western Canada. Better chances of strong to severe storms appears to be Wednesday into Thursday.

Temperatures will be cooler than normal with eastern Nebraska and western Iowa remaining under the influence of large wave trough over the eastern U.S. High temperatures will remain in the 70s and lows mainly in the 50s.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 228 PM CDT Sat Jun 20 2026

Focus in the first 6 hours of the TAFs will be the onset of showers and isolated thunderstorms. A large area of mainly showers is moving into southeast Nebraska. Thunderstorms/lightning remaining west of the CWA for now. As the afternoon progresses, expected coverage of showers to increase, with embedded thunderstorms to increase as well, especially for KLNK and KOMA TAF which appear to be far enough south to tap into better instability and surface-based convection expected to form across the high plains and move eastward. The convective allowing models have been inconsistent in convective development overall, struggling with the location of meso-scale versus syntopic forced development. Thunderstorms still a possibility at KOFK with a frontogenesis at the upper disturbance traversing northern Nebraska.

OAX WATCHES/WARNINGS/ADVISORIES

NE...Flood Watch from 7 PM CDT this evening through Sunday morning for NEZ030-042-043-050-051-065>068-078-088>093. IA...Flood Watch from 7 PM CDT this evening through Sunday morning for IAZ090-091.