Active weather will be the story for the beginning of the extended
forecast period as two severe weather events impact the region this
weekend. The main focus will be a significant severe event that is
expected to impact the region Friday night with all hazards
possible, including strong tornadoes. The other looks to be
primarily a hail and wind threat that impacts southern portions of
the area Sunday afternoon.
An upper ridge to the southeast, and upper trough to the northwest,
aid in strong return flow ahead of a potent system Friday night.
Negative tilt of the trough should aid in deepening a surface low
over the the ArLaTex as it traverses northeastward. An upper level
jet associated with this trough will be oriented SW to NE across the
ArkLaMiss. Tightening pressure gradient from the rapidly deepening
low leads to a strengthening low level jet, with speeds of 55-65
kts. Guidance continues to show mid to upper 60s dewpoints, 1000-
1500 J/Kg SBCAPE, and steep low level lapse rates of 8+ C/Km in the
open warm sector. This very unstable airmass coupled with ample deep
layer shear, should lead to robust storm development ahead of a
surface cold front. Discrete supercell mode is expected initially in
the warm sector aided by prefrontal confluence, which will increase
tornado threat, especially strong tornadoes in the late evening
hours. As storms progress across the southern Mississippi Delta,
some storms could congeal into broken line segments, combined with
40-50 kt 0-3 km bulkshear, QLCS tornadoes could be possible. This
will especially be the case in any bowing segments oriented NW to
SE. In addition to the tornado threat, strong damaging wind gusts of
greater than 70 MPH, and large hail up to golf ball size, are
likely, with deep shear and steep mid level lapse rates. SE ridge
influence will diminish severe threat as the storms progress
eastward, generally after 2 - 3 AM Saturday morning, although some
hazards will still be possible before moving out by daybreak.
