U.S. Severe Weather Forecast (Convective Outlook)

Day Three

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Storm Prediction Center ac 230715 

Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0215 am CDT Sat may 23 2015 

Valid 251200z - 261200z 

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

..There is a marginal risk of severe thunderstorms from the lower MS valley to the 
upper Great Lakes... 

Scattered-numerous thunderstorms will develop from Texas into the 
middle south region on Memorial Day. Scattered thunderstorms will also 
be noted across much of the interior west into the upper Great Lakes 
and Ohio Valley. Greatest risk for severe will be across Texas with 
isolated severe extending north into the upper Great Lakes. 


Northern stream middle-level speed maximum is forecast to dig southeastward along the 
Pacific coast into northern Mexico during the day2 period before ejecting 
into The Big Bend region of Texas early Memorial Day. While deep 
layer shear is not forecast to be particularly strong...sufficient 
surface-6km shear will be present for organized convection and perhaps 
supercell structures if larger convective clusters/line segments do 
not disrupt discrete development. Tropical plume of high 
precipitable water...1.75-2 inches...will persist along a corridor from the western Gulf 
basin into the middle MS valley region. As large scale forcing spreads 
into Texas convection should easily develop...likely early in the 
period then spread toward the arklatex. Given the lack of 
meaningful inhibition numerous storms...clusters and mergers are 
expected. Forecast soundings suggest multi-faceted storm modes and 
sufficient buoyancy for at least a threat of large hail and 
wind...perhaps even a few tornadoes if supercells evolve. Given the 
high precipitable water values these storms will likely produce very heavy rainfall. 

..upper MS valley/Central Plains... 

Day2 short-wave trough is expected to eject north-northeastward into the middle-upper 
MS valley early in the period in response to speed maximum approaching 
The Big Bend. Convection should develop ahead of this feature early 
with large scale ascent likely spreading into northwest Ontario by early 
afternoon. Weak short-wave ridging is expected along the trailing 
frontal zone into the Central Plains during peak heating. Given the 
weak large scale support will only introduce 5 percent severe probs 
across this region for isolated supercells that evolve during the 
late afternoon and linger into the evening hours. 

.Darrow.. 05/23/2015