U.S. Severe Weather Forecast (Convective Outlook)

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Storm Prediction Center ac 181727 


Day 2 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1227 PM CDT Sat Aug 18 2018 


Valid 191200z - 201200z 


..there is a marginal risk of severe thunderstorms from Oklahoma 
and parts of North Texas eastward through Arkansas and the Ozarks... 


... 
A few severe storms will be possible mainly Sunday afternoon and 
evening over parts of the southern Great Plains, Ozarks, and 
Ark-la-tex region. 


... 
With stronger flow aloft confined to Canada Sunday, a relatively 
weaker flow regime will prevail across the Continental U.S.. within this flow 
field however, three areas of troughing are evident. Two -- one 
departing the east and a second moving into/across the Pacific 
northwest -- will contribute to areas of convection, but very little 
severe risk. 


However, limited/low-end severe risk may accompany the third feature 
-- a trough crossing the Great Plains region. This trough will 
contribute to weak surface cyclogenesis -- with a weak low center 
initially in the vicinity of Oklahoma shifting slowly northeast 
across southeast Kansas and eventually into western Missouri. As 
this low develops, a cool front will progress southward across 
Oklahoma and the High Plains of Texas, while a warm front shifts 
north across the mid-Mississippi/Tennessee/lower Ohio valleys later 
in the period. 


Elsewhere, a trailing cold front -- associated with an upper trough 
crossing central Canada -- is expected to move across the northern 
plains/upper Mississippi Valley region through the period, with 
showers and a few thunderstorms likely accompanying. 


..Oklahoma/North Texas east through Arkansas and the Ozarks... 
An ongoing -- though largely disorganized -- cluster of 
thunderstorms is forecast to be crossing the Great Plains region at 
the start of the period, ahead of the advancing upper trough. While 
small hail and gusty winds may be possible with a few of the 
stronger early-day updrafts -- particularly across the Oklahoma 
vicinity -- storms should remain largely sub-severe. 


Though weak cyclogenesis will likely occur through the day, 
lingering clouds/convection will result largely in weak lapse rates 
as well as some hindrance with respect to daytime heating. 
Therefore, although a belt of enhanced (40 kt) westerly mid-level 
flow will spread across this region, convective intensity -- and 
thus severe risk -- should remain limited. Some redevelopment of 
storms near the leading edge of the remnant convection/possible mesoscale convective vortex 
may occur over eastern Oklahoma and into the Ozarks vicinity, while 
some heating in the wake of the convection may allow a few cells to 
develop over southern Kansas and northern/western Oklahoma. While 
gusty winds and marginal hail may occur with a few stronger 
updrafts, overall risk appears likely to remain quite limited 
through the period. 


..maximum risk by hazard... 
Tornado: 2% - marginal 
wind: 5% - marginal 
hail: 5% - marginal 


.Goss.. 08/18/2018 


$$