The watch over southeast Nebraska was issued minutes ago because of high concern at the SPC of a developing MCS moving into the area.
You can see the MCS, or line of severe storms, moving southeast into the watch area. This watch does include Omaha and Lincoln, and the main threat will be strong straight line winds up to 70mph and some golf ball size hail. Off to the west, individual supercells over northern Nebraska where the initial Tornado Watch are have only resulted in one Tornado Warning, which has since expired. The storms are capable of producing large hail and damaging winds, and isolated tornadoes still can't be ruled out.
Other watches for parts of Wyoming, Kansas, Colorado, Idaho, and Montana are in effect for likely non-MCS related wind and hail producing storms. These watches include places like Fort Collins, Loveland, Cheyenne, Billings, Bozeman, and Rapid City. ,