Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0742 AM CDT Mon Aug 14 2017 Valid 141300Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS CENTRAL/EASTERN WY...SOUTHEAST MT...WESTERN SD/NE... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS NORTHEAST NM AND VICINITY... ...SUMMARY... Isolated severe storms are expected in parts of the lee of the central and southern Rockies, and Black Hills vicinity from about 3 to 10 p.m. MDT. ...Lee of the central Rockies and Black Hills vicinity... Within the upper trough across the West, an embedded shortwave impulse along the OR/CA border should progress towards the eastern Great Basin/central Rockies area through early Tuesday. Weak mid-level height falls downstream of this wave should aid in scattered storm development late afternoon across WY into far southeast MT. Given middle 60s or greater surface dew points currently confined to southeast NE and north-central KS, warm-sector buoyancy should initially remain weak with MLCAPE largely below 1000 J/kg at peak heating. However, steep tropospheric lapse rates amid 35-45 kt 500-mb southwesterlies should support a risk for isolated severe wind gusts and marginally severe hail. With strengthening of low-level southeasterlies during the evening, advection of richer boundary-layer moisture may prove sufficient for a couple supercells and all hazards, particularly from northeast WY to the Black Hills. Otherwise, clusters should spread east into western SD and the NE Panhandle, likely weakening in late evening owing to strengthening warm-sector MLCIN and a dearth of buoyancy towards central SD. ...Lee of the southern Rockies... While the overall severe threat should be limited after the TX Panhandle MCS yesterday evening, widely scattered storms will again develop late this afternoon off the Sangre De Cristos. Within a split-flow regime characterized by 50-60 kt 250-mb westerlies, deep-layer shear will be sufficient for updraft rotation in a couple cells. These appear most likely over northeast NM and should offer isolated severe hail and wind. Thus, have added severe probabilities this outlook. ..Grams.. 08/14/2017Read more
from SPC Forecast Products http://ift.tt/rATNzD
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