Day 4-8 Outlook
Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CST Tue Mar 09 2021 Valid 121200Z - 171200Z ...DISCUSSION... ...Friday/Day 4 and Saturday/Day 5... The medium-range models are in decent agreement on Friday, with an upper-level low in the Desert Southwest. Southwest mid-level flow is forecast over the southern Rockies and southern Plains. Elevated thunderstorms may be ongoing at the start of the period in parts of Oklahoma, Kansas and Missouri. The southwestern U.S. upper-level trough is forecast to move eastward during the day. In response, a moist airmass should advect northward into parts of Oklahoma where 60+ surface dewpoints will be possible. A dryline is forecast to take shape by afternoon across far western Oklahoma and west Texas. To the east of the dryline, thunderstorms may develop during the late afternoon and evening along a corridor of instability. Strong deep-layer shear is forecast which may result in a potential for supercells. Large hail and wind damage would be the primary threats. Further to the east from northeastern Oklahoma into southern Missouri, thunderstorms may also develop during the late afternoon and evening. Although deep-layer shear may support an isolated severe threat, the threat may remain marginal due to weak instability. On Saturday, the models continue to be in reasonable agreement, with the upper-level low moving across the Four Corners area. A strong low-level jet is forecast to develop in the southern Plains as the exit region a 80 to 100 kt mid-level jet overspreads the southern High Plains. In response, deep-layer shear will be favorable for supercells with large hail. The current thinking is that a band of strong to severe storms will develop from western Oklahoma southward into northwest Texas Saturday afternoon. This band of storms could continue to be severe, moving into central Oklahoma and north Texas during the mid to late evening. All three hazards can not be ruled out Saturday afternoon and evening. ...Sunday/Day 6 to Tuesday/Day 8... The models continue to be in reasonably good agreement on Sunday and there is not too much spread among GEFS members. An upper-level low is forecast to move into the central High Plains as the mid-level jet moves across the southern Plains. To the east of the jet, a squall-line may develop and move into the Ozarks and Arklatex Sunday afternoon. This squall-line may remain intact across the lower to mid Mississippi Valley during the overnight period. On Monday and Tuesday, model solutions diverge. Although a cold front is expected to move across the Ohio/Tennessee Valleys and Gulf Coast states, substantial uncertainty exists concerning the upper-level level pattern. Strong thunderstorms will be possible along and near the front but uncertainty is high. This uncertainty continues into Tuesday due to very large differences among model solutions.
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