SPC AC 300559

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1259 AM CDT Thu May 30 2024

   Valid 301200Z - 311200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   WEST TEXAS...

   ...SUMMARY...
   Scattered severe storms are expected this afternoon and evening
   across parts of the southern Plains and central High Plains, where
   large hail and wind damage will be possible. The greatest severe
   threat should be in parts of west Texas, where hailstones greater
   than 2 inches in diameter may occur. A more isolated severe threat
   is expected further east across parts of the central Plains,
   Ark-La-Tex and Sabine River Valley.

   ...Southern and Central Plains...
   An upper-level trough will move eastward across the northern High
   Plains today, as west-northwesterly mid-level flow remains over much
   of the southern and central Plains. An MCS is expected to be ongoing
   at the start of the period over parts of Nebraska, Kansas and
   Oklahoma. This convection is forecast to move eastward into the
   Ozarks and Ark-La-Tex during the day, and could be accompanied by a
   marginal severe threat. Further to the west, a shortwave trough is
   forecast to move eastward into the southern High Plains during the
   day. A moist and unstable airmass will be in place ahead of the
   shortwave trough across much of the region. During the afternoon, a
   dryline will likely become focused from southeast Colorado extending
   southward across far eastern New Mexico. As surface temperatures
   warm during the afternoon, scattered convective initiation is
   expected along and to the east of the dryline. As storm coverage
   increases during the late afternoon and early to mid evening, MCS
   development will become likely.

   The airmass to the east of the dryline is forecast to become
   moderately to strongly unstable by afternoon. The deterministic
   models suggest that MLCAPE will reach the 2500 to 4000 J/kg range by
   mid to late afternoon. RAP forecast soundings during the late
   afternoon near the western edge of the moist sector have surface
   dewpoints in the upper 50s F with 0-6 km shear around 40 knots, and
   700-500 mb lapse rates near 8 C/km. This environment will be
   favorable for supercells with large hail. As cells mature during the
   late afternoon and early evening, hailstones over 2 inches in
   diameter will be possible with the more dominant storms. The
   greatest threat for large hail is expected from near Amarillo
   southward to near Lubbock, where the combination of mid-level lapse
   rates and instability is forecast to be most favorable. An isolated
   tornado threat could also develop, and will be dependent upon
   mesoscale factors. As an MCS organizes and moves eastward into
   western Oklahoma and the Texas Low Rolling Plains during the
   evening, a mixed mode is expected with supercell structures and
   short line segments. A threat for severe wind gusts and isolated
   large hail appears likely to continue through much of the evening.
   An isolated and marginal severe threat could continue into the
   overnight period, as the MCS moves southeastward across central and
   east Texas.

   ...Central Plains/Mid Missouri Valley...
   Westerly to west-southwesterly mid-level flow will be in place today
   across much of the north-central U.S. Low-level moisture advection
   will take place across much of the region. Surface dewpoints should
   increase into the mid to upper 50s and lower 60s F from parts of
   northeastern Colorado east-northeastward into eastern Nebraska and
   southeastern South Dakota. As surface temperatures warm across this
   moist airmass, isolated to scattered thunderstorms are expected to
   develop. A few clusters may persist and have potential for a severe
   threat during the late afternoon and early evening. RAP forecast
   soundings from near North Platte eastward into northeast Nebraska
   have 0-6 km shear in the 30 to 40 knot range. In addition, low-level
   lapse rates are forecast to be steep. This suggests that a marginal
   severe threat will be possible with the stronger storms. However,
   the lack of large-scale ascent will likely keep convective coverage
   more isolated, with any severe threat remaining widely spaced.

   ..Broyles/Barnes.. 05/30/2024

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