Mesoscale Discussion 1721
Issued: · Valid: –
Summary
Isolated thunderstorms capable of producing severe downburst winds will move across southeast Idaho and portions of northeast Nevada and northwest Utah through the early evening. These storms may produce wind gusts between 55 and 70 mph.
Product Text
000 ACUS11 KWNS 241902 SWOMCD SPC MCD 241902 IDZ000-UTZ000-NVZ000-242100- Mesoscale Discussion 1721 NWS Storm Prediction Center Norman OK 0202 PM CDT Fri Jul 24 2026 Areas affected...Southeast Idaho and portions of far northeast Nevada and northwest Utah Concerning...Severe potential...Watch unlikely Valid 241902Z - 242100Z Probability of Watch Issuance...20 percent SUMMARY...Isolated thunderstorms capable of producing strong to severe downburst winds will spread across southeast Idaho through early evening. This threat will remain sufficiently limited to preclude watch issuance. DISCUSSION...Latest GOES imagery and lightning data show steady vertical growth of cumulus and the early stages of convective initiation across far northeast NV, northwest UT, and south-central ID. Continued development is expected through mid-afternoon as daytime heating and orographic ascent strengthens and any lingering inhibition is eroded. Immediately downstream from this activity, temperatures are warming into the mid 90s and low 100s with dewpoints mixing into the upper 40s and low 50s. Although RAP mesoanalyses suggests MLCAPE has only increased to around 500 J/kg, modifying a recent 18 UTC LKN based on downstream observations suggests MLCAPE has actually increased to around 1000 J/kg. Consequently, a few robust thunderstorms will likely emerge in the coming hours. The potential for strong/severe downburst winds should increase as this activity spreads into the hotter, more deeply mixed environment air mass within the Snake River Plain - largely driven by the propensity for downdraft accelerations through a ~3 km deep boundary layer. This scenario is reflected in recent HRRR/RRFS solutions, which depict the potential for downbursts winds on the order of 55-70 mph. Despite this potential, modest deep-layer wind shear (sampled by the 18 UTC LKN sounding) suggests that storm modes will most likely remain poorly organized and transient, which limits confidence on the overall coverage/duration of the severe threat and the need for watch issuance. ..Moore/Smith.. 07/24/2026 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...SLC...PIH...BOI...LKN... LAT...LON 41731501 42011522 42221534 42641526 42911499 44281208 44311167 44211138 44011124 43611113 43191115 42921135 42521186 41561452 41731501 MOST PROBABLE PEAK WIND GUST...55-70 MPH