Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0645 PM CST Sun Feb 19 2017 Valid 200100Z - 201200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS TONIGHT ACROSS PARTS OF CENTRAL TEXAS... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS SURROUNDING AREAS OF THE SOUTHERN PLAINS... ...SUMMARY... Strong thunderstorm activity remains possible into and through the overnight hours across parts of the southern Plains, accompanied by a risk for severe hail and potentially damaging wind gusts. ...Plains... Aided by forcing for ascent ahead of increasingly sheared mid/upper troughing now progressing across the southern Rockies, there has been some recent thunderstorm development from portions of the Texas Panhandle into parts of southwestern Nebraska. This is likely occurring in response to weak boundary layer destabilization associated with modest moisture return to the vicinity of surface troughing across the High Plains. And isolated to widely scattered thunderstorms may continue another couple of hours across this region, before boundary layer instability wanes and mid/upper forcing spreads eastward. Highest thunderstorm probabilities appear likely to remain focused within the narrow plume of higher moisture content air (precipitable water in excess of 1 inch) farther to the south and east (currently from just east of Del Rio, Tx into western Oklahoma). This also appears to be along the leading edge of stronger lower/mid tropospheric cooling (around 700 mb). While cooling aloft is expected to advance eastward through much of the remainder of the central and southern Plains tonight, the leading edge of the better low-level moisture return is expected to advect north of the southern Plains Red River Valley toward the mid Missouri Valley. At the moment, severe hail is probably the primary severe threat in the stronger storms, aided by modestly steep mid-level lapse rates, generally cool thermodynamic profiles and strong deep layer shear beneath 50-70 kt southerly 500 mb flow. Low-level flow and shear where the most vigorous storms are currently ongoing is fairly weak. With time, further consolidation of convection into an organizing squall line within the moisture/instability plume is possible tonight. As this spreads eastward with the mid/upper forcing, increasing interaction with a strengthening southerly 850 mb jet (40-50+ kt) across parts of central/eastern Texas and Oklahoma is possible. This could be accompanied by at least some increase in potential for strong surface gusts, particularly across and east of the I-35 corridor of Texas, where surface dew points are higher (mid 60s+ f) and instability probably will be based within the boundary layer. A residual slightly cooler/more stable boundary layer to the north of the Red River may inhibit surface gust potential. ...Intermountain West and adjacent Rockies... Isolated to widely scattered thunderstorm activity lingers beneath the cold trough aloft. However, with the loss of daytime heating, thunderstorm probabilities are expected to become increasingly negligible through the 02-03Z time frame. ..Kerr.. 02/20/2017Read more
from SPC Forecast Products http://ift.tt/rxAC6Z
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