Severe Weather Discussion for April 13, 2007.
**Outbreak of Severe Thunderstorms and Tornadoes Today**
– Significant severe weather event appears likely across the eastern half of Texas today. This is a Particularly Dangerous Situation, with the potential for widespread severe thunderstorms and tornadoes (some strong). Also, destructive hail and damaging winds are likely. The most likely area to be affected is near the I-35 corridor and east into Louisiana.
– Isolated severe thunderstorms are possible in southern Oklahoma, primary threat is hail to quarter size.
– Snow accumulations are likely in the Texas/Oklahoma Panhandles, into northwest Oklahoma. One to three inches of snow should occur through Saturday morning.
– It is emphasized that this is a dangerous situation for the affected areas. Persons are urged to review safety rules and be prepared for quick action should a watch or warning be issued.
Morning surface analysis indicates that retreating warm front is located near Waco and moving north. Air to the south of this boundary is characterized by dewpoints in the upper 60s and low 70s, with temperatures in the low/mid 70s. Cloud cover has been extensive across the threat area this morning, but is beginning to thin across this arear. Indications are that the warm front will continue to move north and may increase speed as pressures fall across the region. The warm front should be near the Red River by late today with little resistance to the north. This will place much of eastern Texas in a warm and moist environment. CAPE values should be around or above 2500 J/Kg across this region with LIs below -6.
12z NAM indicates impressive speed/directional shear will overspread the threat area later today. There appears to be a zone where the 500mb jet max will co-locate with the 700mb jet max from Temple to Dallas/Fort Worth, providing very favorable conditions for supercells and a few strong tornadoes. Elsewhere across eastern Texas, supercells are likely with isolated tornadoes possible. Activity should develop into a squall line late tonight as it moves east into Louisiana.
12z Fort Worth sounding indicates two cap levels, but the one at 700mb is what we'll be dealing with later. Approach of the upper system combined with impressive thermodynamics should breach the cap by 5pm across the region. Models all agree on developing storms along the dryline and warm front this afternoon. Supercells should quickly evolve after moving off the dryline and progress east-northeast. Deviant movers may track east and any storm that can anchor on a boundary will have strong potential at producing tornadoes.
SPC has a moderate risk up for much of the eastern half of Texas, just north of Houston to the Red River. A slight risk surrounds the moderate risk. I think a high risk is warranted, but not like it matters at this point.
Level 1 – Normal
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