LIVE MAP (ABOVE) ... SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0101 AM CDT Thu Jun 15 2023
Valid 151200Z - 161200Z
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTHWEST KANSAS...WESTERN OKLAHOMA AND THE FAR NORTHEAST TEXAS
PANHANDLE...
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS AND GULF COAST REGION...
...SUMMARY...
Widespread severe storms associated with damaging wind gusts, large
hail and a few tornadoes are expected today across parts of the
southern and central Plains. Hailstones greater than 2 inches in
diameter and wind gusts above 70 knots will be likely along the more
intense parts of a fast-moving line of storms. A severe threat is
also expected to develop in parts of the Southeast, and in parts of
the Ohio Valley.
...Significant Severe Weather Event Expected Today Across Parts of
the Southern and Central Plains...
...Southern and Central Plains...
A shortwave trough will move into the central U.S. today, as an
associated 80 to 95 knot upper-level jet moves into the southern
Plains. Ahead of the jet max, a moist and very unstable airmass will
be in place from parts of central and north Texas into western
Oklahoma and the eastern Texas Panhandle. At the surface, a low will
deepen across the southern High Plains as a cold front moves
southward through the central High Plains. Ahead of the front,
surface heating and increasing low-level convergence will likely
result in convective initiation early this afternoon. Storms will
rapidly increase in coverage along an axis of strong instability
from southwest Kansas south-southeastward across the far
northeastern Texas Panhandle and into western Oklahoma. As storms
grow upscale, MCS development is expected to occur late this
afternoon and be maintained through the evening.
By midday, a narrow corridor of maximized low-level moisture is
forecast from northwest Texas extending north-northwestward into
southwest Kansas. MLCAPE is forecast to reach the 3000 to 4500 J/Kg
range by mid afternoon. In addition, RAP forecast soundings have low
to mid-level lapse rates approaching 9.0 C/km. This potent
thermodynamic environment will be augmented by an increase of
deep-layer shear throughout the day, as an upper-level jet moves in
from the west-southwest. Upon approach, an increase in large-scale
ascent will be coupled with strengthening deep-layer shear. RAP
forecast soundings suggest that 0-6 km shear could reach 60 to 70
knots along the instability axis, which will be very favorable for
severe storms.
The current thinking is that cells will first initiate in the early
afternoon, with supercells forming rather quickly. A small cluster
is expected to rapidly expand during the mid afternoon, as a line of
supercells develops. Hailstones of greater than 2 inches in
diameter, along with a tornado threat will be possible with the more
intense supercells. As the convective cluster grows upscale in the
mid to late afternoon, a Derecho will become possible as an
organized severe line segment moves southeastward across the
southern Plains. Wind gusts ahead of the more intense parts of the
line will likely be greater than 70 knots. A few tornadoes will be
possible, along with a continued threat for large hail from late
afternoon into the evening. The MCS, associated with a potential for
damaging wind gusts, could move into the Ark-La-Tex by mid to late
evening, and into parts of the lower Mississippi Valley during the
overnight period.
...Southeast...
A shortwave trough will move through the central Gulf Coast states
today, as a cold front advances southward across toward the central
and eastern Gulf Coast. Ahead of the front, surface dewpoints in the
lower to mid 70s F, will contribute to strong destabilization by
afternoon. MLCAPE is forecast to peak in the 2000 to 3000 J/kg range
by afternoon. Thunderstorms are expected to form ahead of the front,
and will likely be concentrated along pre-existing outflow
boundaries. The greatest coverage could occur from far southern
Alabama extending eastward into northern Florida, where strong
deep-layer shear is forecast to be strong and low-level lapse rates
are forecast to be steep. This should lead to a wind-damage threat
in the late morning and early afternoon, as storms gradually
intensify. An isolated tornado threat and potential for large hail
will also likely exist with the stronger cells. The severe threat
should move toward the immediate coastal areas during the afternoon
as the cold front advances southward.
Further northeast into southeast Georgia and southern South
Carolina, moderate instability is forecast to develop by midday. A
vorticity maximum is expected to move eastward across southern South
Carolina around midday, which should support scattered convective
development. Thunderstorms that form within the stronger instability
could be associated with isolated damaging wind gusts and hail.
...Ohio...
An upper-level trough will move southeastward today across the Great
Lakes region, as a cold front advances southeastward into Indiana
and Ohio. Ahead of the front, surface dewpoints are forecast to be
in the lower 60s F. As surface temperatures warm along the moist
axis during the day, a pocket of moderate instability is forecast by
early afternoon. Thunderstorms will likely form along and ahead of
the front, moving southeastward into the Ohio Valley. RAP forecast
soundings near this maximum in instability have MLCAPE peaking in
the 1500 to 2000 J/kg range, with 0-3 km lapse rates exceeding 8.0
C/Km. This should be enough for a marginal wind-damage threat with
the more intense line segments. A threat for hail will also be
possible.
..Broyles/Bentley.. 06/15/2023
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