Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1130 AM CDT Mon Aug 14 2017 Valid 141630Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE NORTHERN HIGH PLAINS.... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OVER THE SOUTHERN HIGH PLAINS.... ...SUMMARY... Isolated strong to severe storms are expected in parts of the southern High Plains, and in parts of the northern High Plains later this afternoon and evening. ...Northeast Wyoming into adjacent parts of southeast Montana, western South Dakota and western Nebraska... Water vapor imagery shows a strong upper short wave trough moving across northern California as a downstream perturbation lifts northeastward across central Montana. The Montana feature is expected to continue across the northern High Plains tonight and enhance convective potential across the discussion area. Widespread ascent and associated cloud cover is evident across central/eastern Montana which will limit diabatic heating and destabilization this afternoon. Farther south, however, visible imagery indicates breaks in clouds over Wyoming which is expected to promote stronger heating this afternoon. An axis of stronger instability with MLCAPE near 1000-1500 J/kg is forecast to develop into eastern Wyoming, western South Dakota and western Nebraska. Storms are expected to increase in coverage over the mountains of northern Wyoming by mid-afternoon with activity spreading eastward toward the High Plains by evening as orographic circulations coupled with heating and weak large-scale ascent overspreads the area. Veering wind profiles and associated 30-40 kt of effective shear will support a few organized convective structures including isolated supercells during the late afternoon and evening. Stronger storms may produce large hail and strong wind gusts. ...Southern High Plains... Water vapor imagery suggests a weak vorticity maxima is moving slowly eastward along the southeast Colorado/northeast New Mexico border region. Relatively clear skies is promoting strong diabatic heating to occur, and with ample low-level moisture in place, the environment will become increasingly unstable this afternoon with MLCAPE of 2000-3000 J/kg. Despite veering winds with height, weak flow aloft will limit vertical shear across the area. Storms are expected to develop initially over higher terrain this afternoon and spread slowly eastward through the evening. Stronger cells will be capable of producing hail and strong wind gusts, but weak shear is expected to limit overall severe threat. ..Weiss/Jirak.. 08/14/2017Read more
from SPC Forecast Products http://ift.tt/wWCv9s
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