U.S. Severe Weather Forecast (Convective Outlook)

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Storm Prediction Center ac 190445 


Day 2 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1145 PM CDT Friday Apr 18 2014 


Valid 201200z - 211200z 


..there is a slight risk of severe thunderstorms across West Texas... 


... 
isolated severe thunderstorms are expected to develop along a 
dryline across the southern High Plains of West Texas. A few strong 
storms may also develop across portions of western Oklahoma into 
central Kansas. 


..southern/Central Plains... 


Slow-moving upper low is drifting eastward across the lower Colorado River 
valley. This feature is expected to gradually deamplify and eject 
into the southern rockies early Sunday morning with the trough axis 
likely extending across the southern High Plains of West Texas by 21/00z. 
Strongest belt of middle-high level flow will translate over northern Mexico 
with 30-40kt at 500mb forecast to extend over West Texas dryline by 
peak heating. Deep-layer shear should increase enough to support 
sustained rotating updrafts...especially south of I-20 where surface-6km 
values should exceed 40kt. 


Latest model guidance continues to suggest 50s surface dew points will 
advance nwwd into convergent Lee trough/dryline such that ample 
instability should exist by early-middle afternoon for robust updrafts. 
In fact...cooling profiles aloft may allow inhibition to weaken 
enough for thunderstorm initiation fairly early...possibly by 18z. 
However...continued boundary layer heating could result in SBCAPE 
values approaching 1500 j/kg within strongly sheared environment. 
Forecast sounding at maf at 21/00z strongly supports supercell 
development. Convection that evolves across the southern High Plains 
should move east-southeastward though northeastward development along the dryline is 
expected across OK into Kansas. Thunderstorms that develop across the Central 
Plains will do so within considerably weaker shear and forecast 
instability does not appears strong enough to warrant more than 5 
percent severe probs despite scattered coverage expected. 


Large hail is the primary severe threat with supercells along with 
gusty winds. While a brief tornado can not be ruled out over West 
Texas low level shear may be inadequate to support more significant 
tornado threat. 


.Darrow.. 04/19/2014