SPC AC 210552

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1252 AM CDT Thu May 21 2026

   Valid 211200Z - 221200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   EASTERN COLORADO...

   ...SUMMARY...
   Thunderstorms with a threat for large hail, isolated severe gusts
   and possibly a tornado are expected in parts of eastern Colorado
   from mid afternoon to early evening. Isolated large hail will also
   be possible in parts of the southern High Plains this afternoon.

   ...Central and Southern High Plains...
   An upper-level trough will move eastward into the central Rockies
   today. Ahead of the trough, a lee surface low will form over eastern
   Colorado. As surface temperatures warm, convection will initiate in
   the higher terrain near Denver and Colorado Springs. From this
   convection, storms will develop and move eastward into the central
   High Plains during the afternoon. In eastern Colorado, a
   north-to-south axis of instability will be in place by afternoon,
   where model forecasts have MLCAPE peaking around 1500 J/kg. In
   addition, late afternoon RAP forecast soundings in eastern Colorado
   have 0-6 km shear in the 45 to 55 knot range with 700-500 mb lapse
   rates near 8 C/km. This will be favorable for supercells with large
   hail and isolated severe gusts. If a supercell can become locally
   dominant, then a tornado will also be possible. The severe threat
   will likely persist into early evening.

   Further south into the southern High Plains, an axis of instability
   will be in place by afternoon. The strongest instability is forecast
   on the Caprock of west Texas, where 0-6 km shear is forecast to be
   around 30 knots. This, along with 700-500 mb lapse rates near 7
   C/km, may be enough for an isolated large hail threat.

   ..Broyles/Squitieri.. 05/21/2026

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