MD 1314 CONCERNING SEVERE POTENTIAL…WATCH UNLIKELY FOR PORTIONS OF THE WESTERN GREAT BASIN
Mesoscale Discussion 1314 NWS Storm Prediction Center Norman OK 0133 PM CDT Wed Jul 22 2020 Areas affected...portions of the western Great Basin Concerning...Severe potential...Watch unlikely Valid 221833Z - 222030Z Probability of Watch Issuance...5 percent SUMMARY...Scattered thunderstorm development is expected by the mid afternoon hours, and will pose an isolated risk for strong downburst winds and perhaps severe hail. DISCUSSION...Recent GOES visible and IR imagery across the western Great Basin show deepening cumulus with cooling cloud top temperatures developing off of higher terrain across eastern NV as well as within a broad deformation zone ahead of an approaching upper-level low off the CA coast. A few transient lightning strikes have also been noted over the past hour. While sustained convection has yet to develop, these trends suggest that more robust convective initiation is probable in the next 1-2 hours. Elevated instability remains somewhat marginal (widespread MUCAPE values near 500 J/kg), but low-level lapse rates have already steepened to 8-9 C/km across a broad region as a result of deep boundary-layer mixing. Once convection becomes established, a gradual increase in storm intensity is expected through the late afternoon hours as continued boundary-layer warming, coupled with the steep mid-level lapse rates noted in morning soundings, helps augment instability. Additionally, the approach of stronger flow aloft associated with the upper-level wave will help strengthen deep layer shear through the afternoon. The aforementioned steep low-level lapse rates will support the potential for sporadic strong to severe downburst winds. A few instances of severe hail will be possible with any stronger, more organized storm, but widespread severe convection does not appear likely and precludes the need for a watch. ..Hart/Moore.. 07/22/2020 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BOI...LKN...REV...MFR...STO... LAT...LON 39921770 40191866 40302023 40292108 40912140 41472089 41992003 42311903 42311769 42351689 41731478 40711426 39041435 39231540 39521662 39921770
from SPC Mesoscale Discussions https://bit.ly/2amcay0
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