Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1159 PM CST Fri Dec 27 2024
Valid 281200Z - 291200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
FAR EAST TEXAS...LOUISIANA...CENTRAL AND SOUTHERN MISSISSIPPI...AND
FAR WESTERN ALABAMA...
...SUMMARY...
An outbreak of severe storms with tornadoes, wind damage, and large
hail is expected today from parts of the southern Plains, eastward
into the lower Mississippi Valley and central Gulf Coast states.
Several long-track strong tornadoes are expected.
...Tornado Outbreak Likely This Afternoon and Evening Across the
Lower Mississippi Valley and Central Gulf Coast States...
A mid-level trough will move quickly eastward across the southern
Plains today, as an associated mid-level jet moves through the base
of the trough. A surface low will deepen across northeast Texas as a
warm front advances northward into the Ark-La-Tex. Scattered
thunderstorms will first develop near the surface low during the
morning, as surface temperatures warm and as large-scale ascent
rapidly increases due to the approaching system. Isolated large hail
will be the initial severe threat across northeast Texas. The exit
region of a 60 to 80 knot mid-level jet will overspread much of east
Texas around midday, where more vigorous thunderstorms are expected
to develop during the early afternoon. These storms will have
potential to produce severe wind gusts, isolated large hail and
tornadoes. A severe MCS appears likely to intensify and organize as
this activity increases in coverage.
Further to the east, an axis of maximized low-level moisture is
expected to be in place during the early afternoon, oriented from
southern Louisiana into western Mississippi. Surface dewpoints along
and near the axis will be in the mid to upper 60s F. The moist axis
will be aligned with a strengthening low-level jet. Scattered
discrete cells are expected to initiate across the undisturbed moist
sector during the afternoon, with several vigorous storms moving
east-northeastward across the central Gulf Coast states. RAP
forecast soundings near the exit region of the mid-level jet, from
central Louisiana into central Mississippi, show steep mid-level
lapse rates around 8 C/km, with 0-6 km shear in the 45 to 55 knot
range. This environment will support supercell development, with a
potential for strong tornadoes, wind damage and isolated large hail.
Forecast soundings in the early to mid afternoon near the low-level
jet from eastern Louisiana into south-central Mississippi show
backed surface winds to the southeast, and increase 0-3 km
storm-relatively helicity to around 300 m2/s2. This should be
favorable for tornadic supercells. The low-level jet is forecast to
move east-northeastward across the central Gulf Coast states in the
mid to late afternoon. Supercells that can tap the higher surface
dewpoints and stay within or near the axis of the low-level jet
should be able to produce long-track EF3+ tornadoes, and several of
these will be possible.
The severe linear MCS further to the west, is expected to move
quickly eastward across the lower Mississippi Valley during the
afternoon, and will likely be accompanied with widespread severe
wind gusts, with potential for gusts above 65 knots along the more
intense part of the line. By early evening, this line of severe
storms is expected to become the dominant feature across the region.
Widespread wind damage is expected along the leading edge of the
line from the central Gulf Coast states into southern parts of the
Tennessee Valley. Tornadoes will be possible with embedded
supercells within the line, and with line echo wave patterns that
form. Due to the fast-moving mid-level trough, large-scale ascent is
expected to support the severe linear MCS from the evening into the
overnight. A potential for wind damage and tornadoes is expected to
continue after midnight as the line moves across middle Tennessee
and Alabama. The MCS with some severe potential, is expected to move
into the southern Appalachians and northern to central Georgia by
the end of the period.
..Broyles/Thornton.. 12/28/2024
Read more CHECK UPDATE ZOOM GRAPHIC
http://dlvr.it/TH2kmW
