U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus03 kwns 190522 
Storm Prediction Center ac 190521 

Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1221 am CDT Thu Oct 19 2017 

Valid 211200z - 221200z 

..there is an enhanced risk of severe thunderstorms across OK and 
parts of North Texas... 

..there is a slight risk of severe thunderstorms from northwest Texas 
to eastern Kansas... 

..there is a marginal risk of severe thunderstorms from central Texas 
to southwest Iowa... 

Severe thunderstorms, including large hail and damaging winds, will 
develop late Saturday afternoon across eastern Kansas into western 
Oklahoma. Severe squall line will progress into the 
lower/mid-Mississippi Valley during the overnight hours. 

..Texas to Iowa... 

Short-range model guidance supports earlier thoughts regarding the 
evolution of a strong trough as it progresses across the western US 
into the plains Saturday night. As the trough approaches the plains, 
low level jet will strengthen markedly ahead of a pronounced cold front, and 
higher-precipitable water plume will surge north across Texas into portions of the 
eastern Central Plains where values could approach 1.5". Latest data 
suggests a sharp front will extend from western Minnesota, southwest across 
central Kansas into the northern Texas Panhandle at 18z, then into eastern 
Kansas-central OK-northwest Texas by 22/00z. This boundary will be the 
focus for organized severe thunderstorms as it surges southeast. 

Early-day capping will suppress convection along the front until mid 
afternoon across eastern Kansas/western Iowa where inhibition will weaken 
sufficiently for frontal convection, most likely by 21z. Farther 
southwest along the boundary into western OK, strong surface heating 
should contribute to steeper low-level lapse rates as temperatures 
warm into the upper 70s/lower 80s. Substantial SBCAPE (2500-3000 
j/kg) is forecast across western OK prior to convective initiation 
and strengthening shear profiles suggest initial convection across 
this region could be supercellular in nature. However, strong 
large-scale forcing for ascent will contribute to a rapidly maturing 
squall line that should encompass the frontal zone from eastern Kansas 
into southwest OK by 22/00z. Elongated MCS, with possible Bow-type 
structures, should surge east-southeast toward Arkansas and northeast Texas 
during the overnight hours. While a tornado or two can not be ruled 
out given the forecast shear, damaging winds may ultimately be the 
greatest risk with this convection. Additionally, very large hail 
could accompany supercells that develop early in the convective 
cycle over the Southern Plains. 

.Darrow.. 10/19/2017