Mesoscale Discussion 1936 NWS Storm Prediction Center Norman OK 0518 PM CDT Sat Aug 17 2024 Areas affected...portions of northern California into western Oregon Concerning...Severe Thunderstorm Watch 631... Valid 172218Z - 172345Z The severe weather threat for Severe Thunderstorm Watch 631 continues. SUMMARY...The severe threat continues across Severe Thunderstorm Watch 631. Damaging gusts and hail remain the primary concerns. DISCUSSION...Multiple rounds of strong, sustained thunderstorms continue to track north-northwestward in tandem with the stronger mid-level flow. The first round of thunderstorms in OR are comprised of a mix of multicells and transient supercells, likely producing at least small hail (per MRMS mosaic radar data). 6.5-7 C/km tropospheric lapse rates atop low 60s F dewpoints are contributing to over 500 J/kg MLCAPE, which may support a continued risk for strong wind gusts and hail. Farther south into northern CA, a 500 mb speed max is overspreading the area (per 22Z mesoanalysis), supporting locally stronger wind shear and the northward advection of steep mid-level lapse rates. Small but sustained supercell structures have become established in this area, likely accompanied by a hail threat. Steep low-level lapse rates and terrain influences are contributing to overlapping 100+ J/kg 0-3 km CAPE and low-level vertical vorticity, which are also fostering supercell potential. However, 20-30 F T/Td spreads are common across northern CA, indicative of a well-mixed boundary layer supporting strong wind gusts, though a landspout can't be completely ruled out. ..Squitieri.. 08/17/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PDT...MFR...STO...PQR...EKA... LAT...LON 41072188 40382228 40192273 40252317 40552338 44422305 45062274 45302239 45442194 45492128 45422111 45132103 42792141 41072188
Storm Prediction Center Mesoscale Discussion 1936
17
Aug