Mesoscale Discussion 1218
NWS Storm Prediction Center Norman OK
0616 PM CDT Fri Jul 09 2021
Areas affected...Western/central Nebraska...northeast
Concerning...Severe Thunderstorm Watch 356...
Valid 092316Z - 100115Z
The severe weather threat for Severe Thunderstorm Watch 356
SUMMARY...Storm coverage is expected to increase due to increasing
large-scale lift across the central Plains this evening. Large hail
severe wind gusts will remain possible. MCS development is most
likely from the Nebraska Panhandle into central Nebraska, which
would bring a greater severe wind gust threat.
DISCUSSION...Storm coverage has remained isolated across WW 356
likely on account of shortwave ridging aloft. With time, an
approaching shortwave moving southeastward out of Montana as well as
an increasing low-level jet in western Kansas into southwestern
Nebraska will increase large-scale lift. This should lead to
increasing storm coverage in portions of WW 356. CAM guidance has
continued to differ on the exact evolution of the current activity
in western Nebraska/northeast Colorado.
The ongoing supercell in northeast Colorado continues to move toward
better moisture and will be situated near the the low-level jet axis
this evening in western Kansas. This activity could grow upscale and
move southeastward. The downstream environment has seen dewpoint mix
out into the low 60s F making it uncertain as to how far such
activity will progress.
The more likely scenario, based on current observations, is that
storms in the Nebraska Panhandle will continue to grow upscale and
organize along a weak cold front situated north of I-80. Better
mid-level ascent from the approaching shortwave gives greater
confidence in this occurring within the next 2-4 hours.
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