Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1223 AM CDT Sat Aug 15 2020 Valid 151200Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER THE CENTRAL HIGH PLAINS AND NORTHERN MINNESOTA... ...SUMMARY... Isolated severe storms capable of large hail and damaging winds will be possible over the central High Plains as well as northern Minnesota. A more marginal risk for a few severe storms will exist from the Great Lakes into the Midwest region. ...Central High Plains... A modest west to northwest upper flow regime will reside across the central High Plains Saturday. In the low levels an east-southeast post-frontal flow regime will become established. This will result in advection of higher theta-e air beneath steep mid-level lapse rates, contributing to a corridor of moderate to strong instability with 2000-3000 J/kg MLCAPE. Weak forcing aloft and a modest capping inversion may limit thunderstorm coverage. However, at least isolated storms are expected to develop in this regime and activity will subsequently spread southeast. Effective bulk shear from 30-40 kt will support potential for some supercell structures with isolated large hail and locally strong to damaging gusts the main threats. A few storms might evolve into clusters as they develop southeast into the evening before weakening. ...Northern Minnesota... Post frontal low-level moisture with dewpoints only in the 50s F will reside across this region. However, cool temperatures aloft with -14 C at 500 mb along with diabatic warming of the boundary layer will contribute to 500-1000 J/kg MLCAPE. A shortwave trough embedded in the northern stream will approach this area during the afternoon, and at least isolated storms will develop. Effective bulk shear from 40-50 kt will support potential for some supercell structures with large hail and a few strong to damaging gusts the main threat through early evening. ...Great Lakes through the Midwest... Widely scattered to scattered thunderstorms will likely once again develop along an eastward-advancing cold front from the Great Lakes into the Ohio Valley and Midwest regions Saturday afternoon. The environment will be characterized by moderate instability, but the stronger winds aloft will remain north and west of the warm sector with weak vertical shear supportive of multicells. A few storms may produce locally strong wind gusts and hail through early evening. ..Dial/Bentley.. 08/15/2020Read more
from SPC Forecast Products http://www.spc.noaa.gov/products/outlook/day1otlk_1200.html
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