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Mesoscale Discussion 1684 | |
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Mesoscale Discussion 1684 NWS Storm Prediction Center Norman OK 0450 PM CDT Fri Jul 19 2024 Areas affected...southwest South Dakota and west-central Nebraska Concerning...Severe potential...Watch possible Valid 192150Z - 192345Z Probability of Watch Issuance...40 percent SUMMARY...Thunderstorms should gradually increase in coverage and intensity this afternoon/evening. A risk for hail and damaging gusts may evolve. A WW is possible. DISCUSSION...As of 2140 UTC, regional radar and satellite imagery showed isolated thunderstorms developing near a frontal zone across southern SD, northern NE and eastern WY. Warming afternoon surface temperatures in the 80s to 90s F with 50s and 60s F dewpoints are supporting moderate buoyancy of 1500-2500 J/kg across southern SD and western NE. Enhanced mid-level flow ahead of a weak perturbation was observed on area VADs, with effective shear of 35-45 kt. Isolated organized storms, including supercells, appear possible given the favorable CAPE/shear overlap. While mid-level lapse rates are not overly steep (7-7.5 C/km), the moderate buoyancy and potential for updraft rotation suggest a risk for hail with the stronger storms. Damaging gusts are also possible with LCL heights above 2,000 m. Additional storm development/intensification will remain possible late this afternoon and into the evening as weak ascent continues to overspread the central High Plains. Exact storm coverage remains uncertain given the relatively narrow zone of buoyancy and cloud debris from earlier convection. Still, some CAM guidance suggests a cluster or storms may eventually evolve with the potential for hail and damaging winds across parts of southwest SD and west-central NE. While convective evolution and the degree of severe risk remains unclear, conditions will be monitored for a possible WW. ..Lyons/Gleason.. 07/19/2024 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...LBF...UNR...BOU...CYS... LAT...LON 41130338 43940444 44580391 44430294 42640044 41980025 41370043 40930153 41050308 41130338 |
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