Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0758 PM CDT Sat Apr 29 2017 Valid 300100Z - 301200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO TONIGHT ACROSS MUCH OF EASTERN TEXAS INTO PARTS OF SOUTHWESTERN ARKANSAS AND NORTHWESTERN LOUISIANA... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SURROUNDING AREAS OF THE SOUTHEASTERN PLAINS AND NORTHWESTERN GULF COAST INTO THE LOWER MISSISSIPPI VALLEY... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF CENTRAL INDIANA AND ADJACENT WEST CENTRAL OHIO... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE SLIGHT RISK AREA NORTHWARD INTO PORTIONS OF THE LOWER OHIO VALLEY... ...SUMMARY... The risk for severe storms continues tonight across much of eastern Texas into portions of the Ozark Plateau and lower Mississippi Valley, while strong to severe storm development remains possible this evening across parts of the lower Ohio Valley. ...Discussion... As amplified upper troughing gradually shifts east of the southern Rockies, models indicate that there will be significant further deepening of an embedded lower/mid tropospheric cyclone over the southern Plains tonight. The primary surface low center appears likely to redevelop northward from eastern Oklahoma into the lower central Plains/lower Missouri Valley vicinity, but outflow generated by extensive prior and ongoing convection seems likely to delineate the northern extent of any appreciable severe weather potential through the remainder of this period. The outflow boundary has stalled across parts of eastern Oklahoma and northwestern Arkansas through southern Missouri, but continues to advance eastward into the lower Ohio Valley, where mostly low severe weather probabilities are being maintained. Lingering severe weather potential is probably maximized near the intersection of the outflow and a stalled frontal zone (roughly along the I-70 corridor of Indiana), but seems likely to diminish by late evening in the presence of weak/weakening instability. Primary severe weather potential through the evening into the overnight hours is expected to become focused across eastern Texas, into parts of the Ozark Plateau and lower Mississippi Valley by late tonight. The pre-frontal environment across much of eastern Texas remains unaffected by convection and is characterized by large CAPE, with seasonably high boundary layer moisture content (mid 70s surface dew points) residing beneath steep mid-level lapse rates associated with warm and capping elevated mixed layer air. Although this region may remain south/southeast of the strongest deep layer mean wind fields and shear, the environment appears conducive to considerable further convective development tonight. The upscale growth of an extensive mesoscale convective system appears possible, accompanied by the risk for one or more swaths of potentially damaging wind gusts. Any tornadic potential within the evolving system may generally remain focused along a remnant baroclinic zone associated with outflow generated by an earlier storm cluster (the remnants of which now are spreading across/northeast of the Memphis area). ..Kerr.. 04/30/2017Read more
from SPC Forecast Products http://ift.tt/rxAC6Z
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