Storm Prediction Center Mesoscale Discussion 2068

   Mesoscale Discussion 2068
   NWS Storm Prediction Center Norman OK
   0500 PM CDT Sun Sep 15 2024

   Areas affected...portions of northeastern CO...western NE...eastern
   WY...and southwestern SD

   Concerning...Severe potential...Watch unlikely 

   Valid 152200Z - 160030Z

   Probability of Watch Issuance...20 percent

   SUMMARY...Thunderstorms should increase in strength and coverage
   while spreading/developing northward across the central/northern
   High Plains into this evening. The strongest storms will be capable
   of producing severe wind gusts and isolated large hail.

   DISCUSSION...Latest water-vapor imagery depicts an embedded midlevel
   impulse tracking northeastward across portions of northern CO this
   afternoon, and regional VWP shows around 20-30-kt midlevel flow
   accompanying this feature. Associated large-scale ascent will
   promote an increase in thunderstorm development along the
   central/northern High Plains -- generally focused on the moist side
   of a lee trough. Steep deep-layer lapse rates (sampled by recent DEN
   ACARS soundings) amid lower/middle 50s dewpoints are contributing to
   sufficient buoyancy for gradual updraft intensification.
   Additionally, the enhanced midlevel southwesterly flow atop
   low-level southeasterlies is favoring 20-30 kt of effective shear --
   sufficient for loosely organized clusters and brief supercell
   structures. As as result, severe winds gusts and isolated large hail
   will be possible with the strongest storms as they spread/develop
   northward into this evening. Given the increasing large-scale ascent
   and favorable environment for strong convective outflow generation,
   there may be a tendency for localized upscale growth with time,
   which would further increase the severe-wind risk. 

   Current expectation is for the marginal deep-layer shear to limit
   overall convective organization and intensity, and a watch is not
   currently expected. However, convective trends will be monitored
   into this evening.

   ..Weinman/Guyer.. 09/15/2024

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...LBF...UNR...GLD...BOU...CYS...

   LAT...LON   39840198 39800232 40300445 40580467 41730491 42500495
               44300429 44540405 44610364 44500315 43990281 43460267
               42640275 41560262 40150177 39840198