The above graphic accompanied a discussion earlier this morning from the SPC where they decided to upgrade the risk of severe thunderstorms over the red scalloped region of Louisiana and Mississippi.
The frontal boundaries (cold front - blue; dryline - brown; warm front -red) and surface low pressure positions are valid 6pm CST this evening.
This area of higher severe potential lies within a larger overall region (green outlined area) where severe thunderstorms are forecast, as indicated in the latest outlook image below:
As we discussed in a blog post earlier this morning, thunderstorms are expected to develop North of the warm front across Louisiana and Arkansas just about anytime now (in fact, thunderstorms are currently developing in the Shreveport vicinity, Eastward along I-20). Large hail and damaging wind gusts will be possible with this initial round of activity. Thunderstorms developing immediately in vicinity of the warm front may also have enhanced tornado potential.
Later this afternoon, a more isolated (but strong) severe weather threat will develop along the dryline from eastern Oklahoma into northcentral & northeast Texas. Very large hail, damaging winds and isolated tornadoes are possible with any thunderstorm that is able to form in this region.
Later this evening, toward & after sunset, is when a pronounced severe weather threat is expected to develop over Louisiana and Mississippi, into southern Arkansas. Strong, damaging tornadoes will be possible in this region, as indicated by the hatched area on the image below:
In the above "probability of a tornado" forecast image, it is more important to focus on the areas with the higher probabilities, rather than on the percentage chance itself.
As we pointed out in this morning's post, because much of the enhanced severe threat over Louisiana and Mississippi could take place toward or after dark, please take extra precautions if you live in this region. Be sure to monitor the weather via the most reliable source and be prepared to seek shelter should threatening weather approach your area.