U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus03 kwns 280729 
Storm Prediction Center ac 280728 

Day 3 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0228 am CDT Fri Apr 28 2017 

Valid 301200z - 011200z 

..there is a slight risk of severe thunderstorms across parts of 
the Lower/Middle Mississippi Valley... 

..there is a marginal risk of severe thunderstorms from the central 
Gulf Coast to the Midwest... 

Severe thunderstorms will be possible across portions of the lower 
and middle Mississippi Valley Sunday into Sunday night. Damaging 
winds will likely be the primary threat, but large hail and a couple 
tornadoes may also be possible. 

A rather expansive mid-level trough and associated closed low will 
slowly advance eastward across much of the central US. As it does 
so, the low should continue to deepen as it lifts towards the 
Missouri Valley. Meanwhile, ridging will remain established across 
parts of the mid-Atlantic, extending northwestward to the Great 

..portions of the Mississippi Valley... 
Multiple areas of convection are likely to be ongoing across the 
region Sunday morning, as a surface low evolves northeast towards 
Iowa/Illinois and a trailing cold front advances east across the 
Mississippi Valley. Across The Ark-la-miss region, a few of these 
early storms may be severe, with damaging winds likely the main 
threat. Downstream destabilization through the day and strong 
effective shear will likely favor intensification of a band of 
storms pushing eastward during the afternoon and evening. Despite 
strong effective shear, front-parallel vectors suggest mainly linear 
modes, with an attendant threat for damaging winds and perhaps a few 
instances of severe hail. Despite this linear Mode, strong low-level 
shear may support a couple line-embedded tornadoes as well. 

Farther north towards the mid Mississippi Valley, shear vectors may 
be more orthogonal to the front, potentially favoring slightly more 
discrete storm modes (which would support a greater tornado/large 
hail potential). However, convection Saturday night into Sunday 
morning may cast a broad area of rainfall/cloud cover across this 
region, reducing the potential for considerable destabilization and 
precluding a northward expansion of the slight risk at this time. 

.Picca.. 04/28/2017