SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0255 PM CDT Sat May 21 2022
Valid 212000Z - 221200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NEW ENGLAND
TO SOUTHERN TEXAS...
...SUMMARY...
Scattered severe thunderstorms capable of producing both damaging
winds and large hail should continue through evening from parts of
the southern Plains into the lower Ohio Valley, lower Great Lakes
and Northeast.
...20Z Update...
The primary change made to the Day 1 Outlook was to trim higher
severe probabilities behind the convective line across the Mid
Mississippi Valley, as convective overturning has reduced
surface-based buoyancy. Otherwise, the previous forecast remains on
track, with scattered to numerous wind/hail producing thunderstorms
developing ahead of the cold front, from New England to the lower
Mississippi Valley. Please refer to MCDs 0852-0854 for more
information. Likewise, damaging gusts/occasionally large hail may
still accompany ongoing storms across the southeast CONUS (more
details available via MCDs 0855-0856).
..Squitieri.. 05/21/2022
.PREV DISCUSSION... /ISSUED 1046 AM CDT Sat May 21 2022/
...Southern Plains to Northeast...
A complex and active convective day is anticipated for much of the
central and eastern US. Several lines/clusters of strong to severe
thunderstorms are expected to intensify by mid-afternoon along a
cold front and associated outflow boundaries from southeast Ontario
into the Great Lakes region, OH Valley, middle MS Valley and
southern Plains. The air mass ahead of the boundaries is quite
moist with areas of strong daytime heating already occurring. While
large scale forcing mechanisms are generally weak along this broad
corridor, numerous thunderstorms are expected. Strong instability
combined with sufficient flow aloft and steep low-level lapse rates
will result in a risk of locally damaging wind gusts and some hail
along the entire frontal zone. Most areas will see multicell storm
clusters and lines. However, sufficient low and deep layer shear
will likely result in a few supercells moving into northern New
England later today with a slightly higher risk of a tornado or two.
Please reference recent MCDs #848 and #849 for further short-term
details.
...Gulf Coast states into the Carolinas...
There is also a broad area of potential for at least isolated strong
to severe storms over much of the southern and southeastern US
today. Wind fields aloft are relatively weak in most places.
However, strong heating, rich low-level moisture, and relatively
cool temperatures aloft will promote robust up/downdrafts capable of
locally damaging wind gusts and some hail.
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