Day 2 of Severe Weather on Tap for the Southern US on Friday


Day two is on tap for more wild and severe weather on Friday. Already two people dead when a tornado hit near Tushka, OK on Thursday evening. Could we see more destructive weather on Friday? The Storm Prediction Center explains here:

Day 1 convective outlook
National Weather Service Storm Prediction Center Norman OK
1252 am CDT Friday Apr 15 2011
Valid 151200z – 161200z

There is a moderate risk of severe thunderstorms over portions of MS and Alabama…

There is a slight risk of severe thunderstorms over a large portion of the southeastern states…Tennessee and Ohio valleys…

Upper trough currently over the Central Plains will advance through the middle and lower MS valleys Friday…reaching the Tennessee and Ohio valleys Friday night. Attendant surface low will occlude over northern MO while occluded/cold front advances eastward through the middle-lower MS valleys. This boundary will likely extend from the Ohio Valley into the southern Appalachians and the southeastern states by the end of the period. Warm front will lift northward through the central Gulf Coast states and Tennessee Valley during the day.

Southern states: Southerly trajectories east of the occluded low will advect Richer Gulf moisture with middle 60s dewpoints northward through the lower MS valley and portions of southeastern states warm sector. This will contribute to moderate instability as boundary layer warms with MLCAPE from 1500 to 2000 j/kg possible from parts of MS into central/southern Alabama. Potential complicating factor is likelihood of ongoing storms from western Tennessee Valley into the lower MS valley early Friday. Current thinking is that storms may reintensify along southern end of mesoscale convective system and new storms will also likely redevelop along residual outflow boundaries across MS and Alabama as the atmosphere destabilizes.

Stronger low level jet will shift northward through the Tennessee and Ohio valleys early Friday in association with northeastward ejecting lead vorticity lobe. However…low level jet may strengthen farther south across MS/Alabama within exit region of upper jet that will rotate through base of upper trough…maintaining large hodographs in warm sector and near retreating warm front. Potential exists for both supercell and bowing structures as storms reintensify during the day. Threat will exist for tornadoes…large hail and damaging wind with greatest threat of strong tornadoes expected in moderate risk area. Activity will shift eastward through southern parts of the Gulf coastal states overnight with a continued severe threat.

TN through middle MS and Ohio valleys: Partial clearing is expected from western Tennessee…eastern MO into southern and central Illinois in wake of early convection associated with lead vorticity maximum. Diabatic warming and northward advection of upper 50s to near 60f
dewpoints beneath cold air aloft and steep middle level lapse rates will contribute to a relatively narrow corridor of moderate instability. Deeper forcing for ascent within divergent exit region of jet maximum rotating through upper trough base will promote storms redeveloping along eastward advancing cold/occluded front from western Tennessee northward
through eastern MO and Illinois during the afternoon. Strong vertical shear profiles will support supercells with very large hail and isolated tornadoes possible. Activity will shift eastward through portions of the Tennessee and Ohio valleys before weakening during the evening as the boundary layer stabilizes.

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