SPC AC 090829
Day 3 Convective Outlook
NWS Storm Prediction Center Norman OK
0229 AM CST Thu Jan 09 2020
Valid 111200Z - 121200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS EASTERN
LA...SOUTHERN AND CENTRAL MS/AL AND THE WESTERN FL PANHANDLE...
Severe thunderstorms capable of damaging winds and tornadoes are
expected across parts of the southeastern U.S. on Saturday.
...Lower MS Valley through the Southeast States...
The intense southern Plains shortwave trough will lift northeast
across the mid/lower MS Valley through Saturday afternoon, spreading
a 100+ kt southwesterly 500 mb jet streak across the region. A 60+
kt south/southwesterly low level jet will already be in place across
much of the Deep South into the Ohio Valley Saturday morning.
Intense vertical shear will help to maintain a QLCS from the Day 2
period, which will be oriented along a cold front extending
southward from a surface low from eastern AR into south-central LA
at the beginning of the period. Ahead of the QLCS, rich boundary
layer moisture with dewpoints in the upper 60s to near 70 F will
reside as far north as northern MS/AL, with low 60s F as far north
as the lower OH Valley. Given the strength of deep layer flow,
strong, damaging winds are expected to spread eastward across
eastern LA and much of MS/AL and the western FL Panhandle through
late afternoon/early evening. Backed low level flow and at least 500
J/kg MLCAPE should support mesovortex tornadoes as well, especially
across southeast LA into southern/central MS/AL and the western FL
It remains uncertain how pristine the warm sector will remain ahead
of the QLCS and this will impact how much, if any, pre-frontal
semi-discrete convection develops. That being said, a conditional
threat for supercells and accompanying tornadoes (some possibly
strong) will exist across the Enhanced risk area, in addition to the
With northward extent, instability will quickly diminish across TN
into the lower OH Valley, but the intense wind field will support at
least a low-end damaging wind threat into parts of southern KY. The
QLCS likewise should weaken as it tracks eastward into GA Saturday
night, but weak instability and continued strong vertical shear
could support at least low-end severe potential as the front shifts
east into the Carolinas overnight into early Sunday morning.
CLICK TO GET WUUS03 PTSDY3 PRODUCT
NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0830Z