ACUS01 KWNS 011629
SPC AC 011628
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1028 AM CST Wed Mar 01 2017
Valid 011630Z - 021200Z
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM PORTIONS
OF NORTHEAST MS...NORTHERN AL...AND SOUTHERN TN NORTHEASTWARD TO THE
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
ENHANCED FROM PARTS OF THE LOWER MS VALLEY TO SOUTHERN NEW
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT ACROSS PORTIONS OF THE EASTERN STATES...
Severe thunderstorms with damaging winds are expected from portions
of the Southeast to the Mid Atlantic region and parts of southern
New England. Damaging winds will be likely, and the risk for
tornadoes will exist particularly from parts of northeast
Mississippi to portions of north Georgia and vicinity.
...Portions of the Southeast to the Mid-Atlantic region and southern
An extensive belt of strong mid/high-level flow across the Southern
and Eastern States will maintain strong deep shear over a moist and
diurnally destabilizing warm sector across the area. A squall line
from Middle TN toward the central Appalachians will likely spread
across the adjacent Piedmont during the next several hours.
Re-intensification of this activity is expected, owing to the
presence of adequate moisture return (upper 50s to lower 60s
dewpoints) amidst surface heating and relatively steep midlevel
lapse rates. Swaths of damaging wind gusts will be likely as this
activity spreads toward the coastal plain through the evening. A
couple of tornadoes will be possible. Severe-wind probabilities have
been increased eastward across the Piedmont area.
More separated updrafts/discrete convection are evolving across
parts of the lower MS Valley, at the southern end of a zone of
stronger deep ascent. As this activity spreads eastward toward parts
of the southern Appalachians and vicinity, it will intercept a
relatively more moist boundary layer supporting stronger instability
further aided by steep midlevel lapse rates (around 8.5 C/km in the
700-500-mb layer per the 12Z Jackson sounding). With 250-350 m2/s2
of effective SRH associated with modestly curved though long
hodographs, tornado probabilities have been increased in this area.
With northward extent across the East (i.e., toward southern New
England and vicinity), weaker instability will exist owing to more
widespread cloud coverage amidst an antecedent cooler/drier boundary
layer. However, strong vertical shear profiles will support a
conditional severe risk.
Modest destabilization may take place around the upper Ohio Valley
and eastern Great Lakes area amidst recycled moisture ahead of the
primary cold front, perhaps supporting a band of strongly forced
convection spreading eastward from the late afternoon through the
evening. Locally damaging wind gusts may accompany this activity.