SPC AC 150601

   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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