Mesoscale Discussion – Tornado Watch southwest of Chicago area will probably be extended into central Illinois
Mesoscale Discussion 0744
NWS Storm Prediction Center Norman OK
0943 PM CDT Wed May 22 2019
Areas affected...Portions of northeast
Concerning...Tornado Watch 213...
Valid 230243Z - 230415Z
The severe weather threat for Tornado Watch 213 continues.
SUMMARY...Storms in Tornado Watch 213 will continue to move eastward
into an increasingly destabilized environment with strong deep-layer
shear and enlarged low-level hodographs. A continued threat for
tornadoes, large hail, and damaging wind gusts is expected in
central Illinois. A new watch will be needed by 11 PM CDT.
DISCUSSION...Ongoing storms in Tornado Watch 231 have been able to
remain discrete with a few storms beginning to cluster in the
vicinity of Peoria, IL. Several reports of funnel clouds/tornadoes
and strong wind gusts have occurred in the last two hours. The
environment will remain favorable for organized convection given the
50-60 kts of effective shear. More importantly, the downstream
environment of these storms has been steadily improving as a
reservoir of low 70s dewpoints in southern Illinois has begun to
advect northward into central Illinois. This will increase MLCAPE
values ahead of the ongoing convection to 1500 J/kg on the northern
end to perhaps near 3000 J/kg on the southern fringes. RAP forecast
soundings indicate that storms moving into central Illinois should
remain surface-based or nearly-so. The ILX VAD profile has also
shown an increase in low-level veering. As such, a continued threat
for tornadoes, large hail, and damaging wind gusts will persist with
any storms that remain discrete. Some upscale growth is anticipated
as the evening goes on which will reduce the tornado and hail threat
to some degree. However, strong low-level wind fields will still
support a tornado threat even with a QLCS storm mode.
A downstream watch will be needed by 11 PM CDT for the convection
expected to move into central Illinois.