ACUS01 KWNS 301631
SPC AC 301629
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Sun Apr 30 2017
Valid 301630Z - 011200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS DEEP SOUTH TO
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTRAL GULF
COAST TO LOWER GREAT LAKES...
Scattered damaging winds and a few tornadoes are possible across
parts of the Deep South into the Midwest, mainly this afternoon into
A QLCS is ongoing across MS into southeast LA, with a decaying
comma-head MCV over north-central MS. This line should be the
primary focus for a continuing severe threat this afternoon.
Although high-level winds are weak per regional 12Z soundings,
strong low-level shear will continue to support embedded
mesovortices capable of a few tornadoes and damaging winds. The
instability axis will occlude as the eastward surge of the QLCS
outpaces Gulf boundary-layer moisture return, limiting a more
substantial risk farther north in the TN Valley.
Low confidence persists regarding the likelihood of appreciable
destabilization in a scenario that appears otherwise favorable for
severe storms given ample deep-layer/low-level shear. This low
confidence is related to extensive convection ongoing from the
Mid-MS Valley into the Mid/Deep South. A couple clusters of severe
storms may develop downstream of this midday activity across parts
of IN/KY/OH where diabatic heating should be more pronounced amid
middle 60s surface dew points. Farther west over the Mid-MS Valley
in the wake of the midday convection, widely scattered storms should
attempt to form late afternoon along/near the cold front/surface
cyclone track. Instability will probably remain rather weak and
deep-layer winds meridional, suggesting overall severe coverage
should be isolated.