SPC Aug 10, 2017 1730 UTC Day 2 Convective Outlook

By Newsroom America Feeds at 10 Aug 13:32

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1229 PM CDT Thu Aug 10 2017 Valid 111200Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE CENTRAL AND NORTHERN HIGH PLAINS... ...SUMMARY... Isolated strong to severe storms will be possible across portions of the central and northern High Plains Friday afternoon and evening, producing mainly strong, damaging wind gusts and hail. ...Northeast CO/eastern WY/western NE/western SD... Broad cyclonic midlevel flow regime will be maintained this forecast period across the northern and central High Plains to the Mid-Atlantic and Northeast states. An embedded shortwave trough is expected to shift east of the mid MS Valley, while the next upstream shortwave trough, now tracking south per water vapor imagery across Alberta, should move into the northern High Plains Friday night. Meanwhile, forcing for ascent attendant to a weak midlevel impulse expected to move into this Marginal risk area by peak heating Friday afternoon and height falls Friday night with the Alberta trough should prove favorable for convective development. Vertically veering winds with westerly 500-mb winds at 35-40 kt will result in effective bulk shear of 35-50 kt. Although lapse rates will be steep and surface heating will contribute to destabilization, the lack of greater low-level moisture should result in MLCAPE of 500-1000 J/kg. A Marginal risk of severe storms exists from northeast CO to eastern WY and western parts of SD/NE as storms develop over the higher terrain and spread to the east. A strengthening southerly low-level jet could result in some upscale growth of storms across the eastern parts of the Marginal risk area Friday night. Damaging winds and hail will be the primary severe threats, with CAPE/shear parameter space supporting some supercell development. ...AR/northern MS/western TN... Stronger westerly 500-mb winds and effective bulk shear forecast by the 12Z NAM appear to be an outlier compared to other deterministic models, with this region located mainly south of the corridor of stronger westerly flow aloft. This combined with the lack of discernible midlevel forcing for ascent and weak lapse rates suggests storms that develop across this region Friday into Friday evening are expected to be generally non-severe, with the severe probability being less than 5%. ..Peters.. 08/10/2017 Read more



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