Mesoscale Discussion 0460 NWS Storm Prediction Center Norman OK 0533 PM CDT Thu Apr 17 2025 Areas affected...eastern Nebraska Concerning...Tornado Watch 141... Valid 172233Z - 180000Z The severe weather threat for Tornado Watch 141 continues. SUMMARY...The greatest large to very large (2 to 3.5 inch) hail and severe wind threat will exist ahead of a supercell in east-central Nebraska this evening, potentially impacting the Omaha metro area. A tornado threat will also increase near sunset. DISCUSSION...A supercell has developed slightly north of the cold front in Hamilton County, Nebraska. An additional storm has developed to its northeast along this frontal zone. One or 2 dominant supercells are expected to emerge out of this as they move east this evening. Some slowing of the surface front, augmentation of the boundary by the developing supercell, and eastward acceleration of the storms should allow them to move along or possibly even ahead of the front by later this evening. The environment ahead of this activity is very favorable for supercell maintenance and the potential for large to very large hail. Modifying the OAX 20Z RAOB for the environment slightly ahead of this storms (87/59F) shows an uncapped parcel with nearly 3000 J/kg MLCAPE, ample buoyancy through the hail growth zone, and 50-60 knots of effective shear. This, combined with expectation for a discrete storm mode, will support very large hail (baseball to softball size) with the strongest supercells. The 21Z WoFs highlights the corridor of the greatest threat ahead of the ongoing supercell into western Iowa by later this evening with WoFS hailcast also indicating peak hail size around 2.75" this evening. In addition, WoFs shows a peak STP around 2 to 3 around 00Z near the Missouri River which will correspond well with peak intensity and location of the ongoing supercell. Therefore, there will be a favorable time window around 00Z to 01Z as the low-level jet strengthens when the tornado threat will be maximized. ..Bentley.. 04/17/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...OAX...GID... LAT...LON 40729789 40809808 40989816 41139813 41579740 41739635 41669555 41409529 41089531 40909635 40799755 40729789 MOST PROBABLE PEAK TORNADO INTENSITY...100-130 MPH MOST PROBABLE PEAK WIND GUST...65-80 MPH MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN
Category: Watches, Warnings, Advisories, & Hazards