LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1252 AM CDT Mon May 08 2023
Valid 081200Z - 091200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE MID MISSISSIPPI VALLEY INTO THE OHIO VALLEY...AND PORTIONS OF
THE SOUTHERN PLAINS...
...SUMMARY...
Scattered severe thunderstorms should occur today from the mid
Mississippi Valley into the Ohio Valley, with damaging winds and
large hail the main threats. A separate area of severe thunderstorms
may occur across parts of the southern Plains.
...Mid Mississippi Valley into the Ohio Valley...
An MCS will likely still be ongoing at the start of the period later
this morning across parts of the mid MS Valley into the lower OH
Valley. Most guidance suggests this convective cluster should weaken
through the late morning as it advances east-southeastward. But, an
isolated threat for mainly damaging winds may persist with this
activity if it can remain surface based. In the wake of the morning
convection, nearly all guidance suggests that moderate to locally
strong instability will develop ahead of a front from
central/southern MO northeastward across much of the OH Valley, as
steep mid-level lapse rates emanating from an EML over the central
Plains spread eastward. With clouds/convective debris from the
morning activity probably still present over parts of this region,
the degree of instability that can develop is still somewhat
uncertain.
However, it does appear likely that additional robust thunderstorms
will form by mid to late afternoon along/south of a front, as a
weak/low-amplitude shortwave trough moves eastward across the OH
Valley. Deep-layer shear appears strong enough for supercells with
the initial development, and scattered large hail may be the initial
severe hazard. With time, one or more bowing clusters will likely
develop and spread southward/eastward through the late afternoon and
early evening. As this mode transition occurs, severe/damaging winds
will probably become the main threat. Although low-level winds are
forecast to mostly veered to west-southwesterly and not overly
strong, there may still be an opportunity for a tornado or two with
any supercell that can be sustained. Given trends in 00Z guidance
for greater instability and thunderstorm coverage across IN into
eastern KY/southwestern OH and the central Appalachians, have
expanded both the Marginal and Slight Risk areas east-northeastward
to encompass this potential severe threat.
...Southern Plains...
Similar to the last few days, isolated to widely scattered
thunderstorms should develop once again late this afternoon and
evening along/east of a dryline that will be located across parts of
west TX. While deep-layer shear is forecast to remain quite modest,
strong to very strong instability is forecast owing to robust
daytime heating of a moist low-level airmass, and the presence of
steep mid-level lapse rates. Although convection that develops may
tend to be fairly disorganized, the ample instability should aid in
the development of robust updrafts and compensate to some extent for
the weak deep-layer shear.
A Slight Risk has been added where the greatest concentration of
convection is forecast, with both large hail and severe wind gusts
possible. The Marginal Risk has also been expanded eastward to
include more of central into south-central TX, as some guidance
suggests convection emanating from northern Mexico may persist and
pose some severe risk into these areas through the evening.
..Gleason/Lyons.. 05/08/2023
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/SnhYzQ
