SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1151 PM CST Sat Jan 23 2021 Valid 241200Z - 251200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE SOUTHEASTERN OKLAHOMA AND NORTH TEXAS... ...SUMMARY... A few severe thunderstorms capable of producing large hail and isolated wind damage will be possible this afternoon through tonight across parts of the southern Plains. ...Southern Plains/Ozarks... An upper-level trough will move eastward across the Desert Southwest today as southwest mid-level flow becomes established in the southern Plains. At the surface, a cold front will advance southeastward across the southern Plains today as moisture advection occurs to the south of the front. By afternoon, the front position should be located from near Lubbock northeastward into southern Oklahoma. Surface dewpoints to the south of the front in the Red River Valley and across northwest Texas are forecast to be mostly in the 50s F. A capping inversion should prevent convection from initiating for much of the day. But as surface heating and low-level convergence increase, isolated thunderstorms appear likely to develop in north Texas along and just ahead of the front during the late afternoon. Convection is forecast to expand rapidly in the early evening as warm advection increases across north Texas and southern Oklahoma. Thunderstorm development should continue across much of Oklahoma, north Texas and Arkansas as the upper-level trough approaches during the overnight period. Instability is forecast to gradually increase today to the south of the front across central and north Texas. By early evening, a pocket of moderate instability may develop across parts of west-central Texas. As instability increases during the evening, a severe threat will be possible in southern Oklahoma and north Texas. NAM forecast soundings to the west of the Dallas/Fort Worth Metro during the early evening have MLCAPE reaching 1000 J/kg. Effective shear is forecast to gradually increase from around 55 kt at 00Z to 70 kt at 06Z. As a result, the severe threat is forecast to gradually increase during the evening. Forecast soundings suggest that the steepest lapse rates will be located above 700 mb. This will be favorable for hail, especially with supercells that can organize. Isolated strong wind gusts may also occur in southern Oklahoma and north Texas as cells become more surface-based during the evening. Thunderstorms, accompanied by an isolated severe threat, are forecast to move eastward across southeast Oklahoma and northeast Texas in the mid to late evening. A marginal severe threat may also develop in parts of Arkansas during the overnight period as warm advection increases. ..Broyles/Lyons.. 01/24/2021
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