|Mesoscale Discussion 1797|
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Mesoscale Discussion 1797
NWS Storm Prediction Center Norman OK
0841 PM CDT Sun Sep 18 2022
Areas affected...much of southern Iowa into far northern Missouri
and northwest Illinois
Concerning...Tornado Watch 536...
Valid 190141Z - 190445Z
The severe weather threat for Tornado Watch 536 continues.
SUMMARY...A gradual ramp up in storm intensity and coverage remains
possible over the next few hours. An additional watch could be
needed downstream into Illinois, dependent on trends.
DISCUSSION...A few strong storms currently exist in a weak warm
advection zone over eastern IA into northwest IL, with more robust
development now noted along the IA/MO border. Surface analysis shows
little surface convergence and in face very weak wind speeds. Just
off the surface, 850 winds are gradually increasing out of the
west/southwest, with glancing theta-e advection into the region.
The best deep-layer theta-e appears to exist from southern IA into
northern MO per objective analysis, and any storms that develop in
these areas may have the greatest potential to eventually become
severe. Long hodographs will favor large hail, with severe wind
threat dependent on how many storms can form with merging outflows.
If this occurs, another watch may be required eastward into IL.
...Please see www.spc.noaa.gov for graphic product...
LAT...LON 40589451 40909485 41539446 41979133 41759033 41058946
40338921 39878962 39789075 39959234 39959234 40589451
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