SPC AC 010100

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0800 PM CDT Tue Apr 30 2024

   Valid 010100Z - 011200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM PARTS OF THE
   SOUTHERN PLAINS NORTH-NORTHEASTWARD INTO THE UPPER MISSISSIPPI
   VALLEY...

   ...SUMMARY...
   Severe storms, capable of large hail (possibly above 2 inches in
   diameter), damaging wind gusts, and a few tornadoes are expected
   this evening from the upper Mississippi Valley south-southwestward
   into the southern Plains.

   ...Central Plains/Lower Missouri Valley/Upper Mississippi Valley...
   The latest surface analysis has a 1002 mb low over southwest Iowa,
   with a narrow corridor of maximized low-level moisture from near the
   low southwestward into eastern Kansas. The RAP has moderate
   instability along this corridor with MLCAPE estimated to be in the
   1500 to 3000 J/kg range. Scattered strong to severe storms are
   ongoing along and near the instability axis. These storms will
   continue to move eastward toward the upper Mississippi Valley and
   Ozarks this evening. In addition to the instability, WSR-88D VWPs
   near the instability axis from northwest Missouri southwestward into
   southeast Kansas have 0-6 km shear in the 35 to 40 knot range.
   Within this area, RAP forecast soundings suggest that 700-500 mb
   lapse rates are in the 7 to 7.5 C/km range. This will continue to be
   favorable for supercells with large hail over the next few hours.
   The more dominant supercells could produce hailstones greater than 2
   inches in diameter. Strong low-level shear was also evident on the
   WSR-88D VWPs suggesting a few tornadoes could develop. Severe wind
   gusts also could occur with supercells or short line segments. The
   severe threat is expected to continue through much of the evening,
   but should become more isolated and marginal, especially toward late
   evening.

   ...Southern Plains...
   Westerly mid-level flow is evident on water vapor imagery over the
   southern Plains this evening. At the surface, a moist airmass exists
   throughout much of Texas and Oklahoma. Scattered thunderstorms are
   ongoing to the east of a dryline, near the western edge of the moist
   airmass, from western Oklahoma into west-central Texas. The 00Z
   soundings at Norman and Midland are showing MLCAPE in the 2000 to
   3500 J/kg range. Regional WSR-88D VWPs show moderate deep-layer
   shear over much of the southern Plains, with 0-6 km shear generally
   in the 40 to 45 knot range. This, along with 700-500 mb lapse rates
   near 7.5 C/km, will support supercell development this evening, with
   a potential for large hail. Hailstones of greater than 2 inches in
   diameter will be possible with the more intense cells. An isolated
   tornado threat could continue in southwest Oklahoma for another hour
   or so. A few damaging wind gusts could also occur. The severe threat
   should become more isolated during the mid to late evening, as a cap
   begins to build in across much of the southern Plains.

   ...Mid-Atlantic To Far Southwest New England...
   The latest radar imagery shows a cluster of strong to severe
   thunderstorms located over far eastern Pennsylvania and northwestern
   New Jersey. This cluster was located just to the north of a 1009 mb
   low, along the northeastern edge of a pocket of maximized low-level
   moisture. Within this pocket, surface dewpoints are in the mid to
   upper 50s F, an MLCAPE is estimated to be in the 250 to 500 J/kg
   range, according to the RAP. This cluster of storms should weak, as
   it moves east-southeastward toward the coast this evening. A few
   marginally severe wind gusts will be possible.

   ..Broyles.. 05/01/2024

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