Storm Prediction Center Mesoscale Discussion 2304

   Mesoscale Discussion 2304
   NWS Storm Prediction Center Norman OK
   0246 PM CDT Thu Sep 17 2026

   Areas affected...Parts of southern and central Idaho

   Concerning...Severe potential...Watch unlikely 

   Valid 171946Z - 172215Z

   Probability of Watch Issuance...20 percent

   SUMMARY...The risk of a few severe storms capable of producing large
   hail and severe wind gusts will increase through the remainder of
   the afternoon. A watch is not currently expected, though trends are
   being monitored.

   DISCUSSION...Thunderstorms are gradually increasing in coverage
   across parts of southern and central ID. These storms are being
   aided by increasing large-scale forcing for ascent preceding a
   closed midlevel low over northern CA and localized terrain
   circulations. These storms will continue developing and spreading
   northward across southern into central ID this afternoon, given deep
   southerly steering flow. The 18Z BOI sounding sampled steep
   deep-layer lapse rates and an elongating/mostly straight hodograph
   (around 30-40 kt of cloud-layer shear per VWP and mesoanalysis
   data). Initially, cellular storms will pose a risk of large hail and
   locally severe wind gusts. With time, storms may organize into small
   clusters and pose an increasing risk of severe wind gusts.

   Currently, the risk appears too localized for a watch, though
   convective trends are being monitored.

   ..Weinman/Hart.. 09/17/2026

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

   ATTN...WFO...PIH...MSO...BOI...

   LAT...LON   42241289 42401350 42681421 43511524 43861557 44261571
               44561562 44741525 44731470 44431345 44131257 43801213
               43221198 42691207 42271250 42241289 

   MOST PROBABLE PEAK WIND GUST...55-70 MPH
   MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN