SPC Aug 12, 2017 1730 UTC Day 2 Convective Outlook

By Newsroom America Feeds at 12 Aug 13:33

SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1228 PM CDT Sat Aug 12 2017 Valid 131200Z - 141200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF THE CENTRAL HIGH PLAINS AREA... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE HIGH PLAINS SLIGHT RISK...AND INCLUDING A LARGE PORTION OF THE HIGH PLAINS AREA... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF MAINE... ...SUMMARY... Scattered thunderstorms, a few severe, are expected to develop across the central and southern High Plains Sunday. A strong storm or two may also affect portions of Maine. ...Synopsis... Low-amplitude/generally cyclonic flow aloft is forecast to prevail over much of the U.S. Sunday, surrounding the southern extension of two Canadian troughs -- one over western and the other over eastern Canada. At the surface, a cold front is forecast to move east across New England through the first half of the period. Trailing portions of this boundary will linger east-to-west across the Gulf Coast states and southern Plains. In the West, a front is forecast to shift east/east-southeast across the northwest quarter of the U.S. through early Monday. ...High Plains vicinity... Heating/destabilization is forecast through the day across the High Plains, which will support isolated afternoon storm development, aided by ascent associated with height falls ahead of troughing digging southeast across the northwest states. With some increase in west-northwest flow aloft expected ahead of this trough atop low-level southerly/southeasterly flow, shear sufficient for both storm organization, and southeast propagation off the higher terrain, suggests that a few severe storms should evolve through the afternoon and evening hours. Zone of greatest risk remains difficult to accurately discern at this time, but will maintain SLGT risk over the central High Plains vicinity, where models continue to forecast greatest afternoon destabilization to likely occur. ...Maine... As a vort max crosses northern New England during the day, cool air aloft combined with diurnal heating should support modest CAPE development -- sufficient for development of showers and a few thunderstorms. While convection should diminish through mid to late afternoon as the vort max shifts into New Brunswick/Nova Scotia, a strong storm or two -- possibly capable of producing a locally damaging gust or two -- may occur from late morning through early afternoon. ..Goss.. 08/12/2017 Read more



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