Mesoscale Discussion 1061
NWS Storm Prediction Center Norman OK
0616 PM CDT Fri Jun 16 2017
Areas affected...Portions of the mid Missouri Valley
Concerning...Severe Thunderstorm Watch 339...
Valid 162316Z - 170115Z
The severe weather threat for Severe Thunderstorm Watch 339
SUMMARY...A line of significant severe thunderstorms will move
through the Omaha metro area over the next couple of hours. Damaging
wind gusts (a few of which could be 75+ mph), large hail, and
tornadoes will remain possible.
DISCUSSION...Regional radar data depict a cluster of
high-precipitation supercells across eastern Nebraska early this
evening. These storms have already produced an array of severe
weather, including a gust to 74 mph at Norfolk, NE as a stout
mesocyclone passed the site. As of 2300Z, KOAX data exhibited at
least two strong rear-flank downdraft surges within this line of
embedded supercells. These surges should support a continued upscale
growth of these cells into a bowing complex that accelerates rapidly
southeast towards Omaha, likely reaching the metro area around
00-01Z (7-8pm CDT).
A 21Z OAX observed sounding sampled a thermodynamic profile quite
favorable for damaging wind gusts. Moreover, low-level and
deep-layer shear suggest very large hail and tornadoes will remain
possible in any discrete or embedded supercellular elements.
Therefore, all severe hazards remain possible with these storms, and
damaging gusts (some of which could be over 75 mph) appear likely
in/around the Omaha and Lincoln areas within the next 1-2 hours.
Additionally, downstream watch issuance in Iowa/Missouri will likely
be needed within the next two hours.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 41389884 42239762 42379620 42269598 42029561 40919430
39719435 39369525 39409672 40029797 40559851 41049892