SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Sat Aug 20 2022
Valid 202000Z - 211200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
CENTRAL ILLINOIS AND FROM SOUTHEAST INDIANA INTO SOUTHWESTERN
OHIO...
...SUMMARY...
Scattered severe storms with damaging winds and large hail will be
possible this afternoon and evening across central Illinois and from
eastern Indiana into western Ohio.
...20Z Update...
The previous forecast reasoning remains valid. No changes were made
with this update.
..Wendt.. 08/20/2022
.PREV DISCUSSION... /ISSUED 1132 AM CDT Sat Aug 20 2022/
..Midwest/Ohio Valley/Ozarks...
A weak surface low over central IA will move slowly southeast
through tonight as an associated cold front also moves east,
extending from west-central IL into central MO and southern KS by
00z. Despite ongoing precipitation/cloud cover over portions of
IL/IN, pockets of more substantial destabilization are expected by
afternoon, especially from southern/eastern IN into southwest OH
where slightly higher boundary layer moisture exists and stronger
heating is expected. With minimal CINH by early/mid afternoon, more
concentrated thunderstorm development or re-intensification is
expected near the cold front/upper low across eastern IA/central IL,
with a second area over eastern IN/western OH. Elsewhere, more
isolated strong/severe storms will be possible within the Marginal
Risk area near and in advance of the front with severe winds the
primary hazard.
Southwesterly mid-level flow will contribute to effective shear
ranging from 30-35 kts this afternoon which will support multicells
and a few transient supercell structures. Damaging winds will be
the primary severe hazard, with instances of large hail also
possible primarily over eastern IA/central IL where cooler mid-level
temperatures will exist. Some potential for low-level rotation may
exist with supercell structures east of the surface low this
afternoon, and have retained the low tornado probabilities in this
area.
...South Texas...
A low over the western Gulf of Mexico is expected to move
northwestward toward Deep South Texas. Refer to the latest National
Hurricane Center advisory for additional forecast details regarding
Potential Tropical Cyclone Four. While a modest strengthening of
southeasterly low-level winds may occur, present indications are
that the low/mid-level wind field will likely remain sufficiently
weak to preclude a tornado risk.
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/SWz319
