|Mesoscale Discussion 209|
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Mesoscale Discussion 0209
NWS Storm Prediction Center Norman OK
0543 PM CDT Thu Mar 19 2020
Areas affected...Southeast Nebraska...parts of southern
Iowa...northwest Missouri...northeast Kansas
Concerning...Tornado Watch 57...
Valid 192243Z - 200045Z
The severe weather threat for Tornado Watch 57 continues.
SUMMARY...Severe threat is expected to continue across Tornado watch
0057 for at least the next few hours. Large hail will be the primary
threat with most of these storms. The best tornado potential will be
confined to the warm side of a baroclinic zone across southwest IA.
Additional storms are developing across northeast Kansas and may
pose some severe risk should they intensify.
DISCUSSION...Semi-discrete transient supercells have been in
progress across southeast NE into southwest IA over the past few
hours, with a history of severe hail. Adequate instability (1000+
J/kg MLCAPE) and ample deep-layer shear (60+ knot effective bulk
shear) remains in place across southeast NE into south-central IA,
suggesting that severe potential should continue into the evening
hours. Many of the storms have crossed over or have been undercut by
a baroclinic boundary draped across far southeast NE into southwest
IA. These storms will likely remain elevated and produce mainly
severe hail. Any storm that can become surface based and mature
previous to crossing the boundary may produce a tornado given the
adequate streamwise vorticity in place.
Deep-layer ascent should continue to overspread the
Upper-Mississippi Valley with the approach of both the surface low
and a well-defined mid-level vort max through the evening,
potentially promoting the development of new storms. Storms have
recently initiated across parts of northeast Kansas and these too
may become severe as they move closer to the aforementioned
boundary, where stronger deep-layer ascent is present. This new
development will continue to be monitored over the next few hours.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 39089695 40249737 41079728 41429618 41669508 41769376
41739296 41679258 41539227 41239221 40399298 39219592
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