U.S. Severe Weather Forecast (Convective Outlook)

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Day Three

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Storm Prediction Center ac 240712 


Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0212 am CDT Thursday Apr 24 2014 


Valid 261200z - 271200z 


..there is a slight risk of severe thunderstorms across the central and Southern 
Plains... 


... 
Scattered severe thunderstorms are expected to develop along a 
dryline across portions of Kansas...Oklahoma...and parts of West 
Texas. Very large hail...and possibly tornadoes...can be expected. 


..central and Southern Plains... 


Strong middle-level speed maximum is forecast to round the base of a 
progressive trough along the southwestern U.S./Mexican border early Saturday 
before shifting into nm by 27/00z. This feature will then eject 
into the Central High plains of western Kansas overnight...increasing to 
80kt+ at 500mb. Intense 12-hour middle-level height falls...approaching 
200m...will develop across the High Plains centered on southeastern Colorado. 


As upper trough shifts into the southern rockies...surface low will deepen 
over eastern Colorado and a well-defined Lee trough will extend southward into northern 
Mexico. Intense heating is expected along this trough during the 
day and a dryline should mix into the eastern Texas Panhandle by 21z. 
While warm sector boundary layer moisture is expected to gradually 
increase across the southern/Central Plains over the next few days it 
appears dryline convection may initially ingest 50s surface dew points 
as temperatures rise through the 80s...to perhaps near 90f farther 
south across the Edwards Plateau. Convective temperatures should be 
breached by 21z and scattered supercells are expected to develop along the 
boundary. This activity will initially be driven by diabatic 
heating as large-scale forcing associated with approaching speed maximum 
will lag this corridor of initiation until well after dark. Delayed 
large-scale support may limit the number of storms that ultimately 
evolve along the dryline. 


Convection that develops during the late afternoon will do so along 
a narrow corridor of 3000 j/kg SBCAPE and should mature into the 
early evening hours as vertical shear increases from the west. 
Supercells with very large hail...greater than 2 inches...are 
expected. As thunderstorms shift east and boundary layer cools slightly 
there may be a propensity for cloud bases to lower and take 
advantage of lower 60s surface dew points. As a result...tornado threat 
should increase during the early evening hours before activity 
decouples from the boundary layer. 


With large scale forcing expected to eject into the plains overnight 
there may be convective redevelopment along the dryline as it begins 
to surge across southwestern Kansas/western OK/northwestern Texas. 


Severe probabilities may be increased across this region if 
middle-level speed maximum/forcing overspreads the dryline at a more 
favorable time diurnally. 


.Darrow.. 04/24/2014