Dangerous Set Up for Easter Sunday

From the Storm Prediction Center:

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FROM NORTHERN LOUISIANA THROUGH SOUTHEAST ARKANSAS...MISSISSIPPI INTO CENTRAL AND NORTHERN ALABAMA...

SUMMARY... An outbreak of severe thunderstorms appears likely Sunday into Sunday night, with the greatest threat expected from Louisiana through much of the Southeast and Tennessee Valley. Strong tornadoes, potentially widespread damaging winds, and large hail are all possible.

Storm Dynamics

I shared this gif earlier to my twitter and fb feeds.. showing the INTENSE wind field that is expected to develop with this storm as we go through the next couple of days with 850 mb winds approaching 80 to 90 knots. That translates to nearly 100 mph wind in some cases just 4 or 5,000 feet off the ground. Wow.

Convective Available Potential Energy

While the area of severe potential will be very large.. the one limiting factor, as is often the case this time of the year, will be the amount of CAPE (convective available potential energy). This represents the amount of fuel or instability available for storms to feed off of. As of this writing, the highest cape values of 2 to 4,000 units appears likely to be in place for parts of the Lower Mississippi River Valley and into parts of Dixie.

These numbers represent high instability and will provide fuel for explosive development as storms generateduring the late afternoon/evening hours on Sunday. Further north, instability will be limited by earlier rounds of rain/storms possibly reducing the severe threat northward into the Tenessee and Ohio River Valleys. However, this too will need to be monitored as even modest amounts of CAPE could lead to the development of severe storms.

Significant Tornado Parameter

Taking both the incredible amount of wind energy that will be available and the potential for high instability brings us to STP... or Significant Tornado Parameter. This is an index that is used to diagnose the potential development of strong tornadoes (EF2-EF5) that takes into account many variables including the above mentioned wind dynamics and thermodynamics (instability). With that being said, the latest STP numbers via the 3k NAM continue to advertise some downright jarring figures with a vast area spiking well above 10 and even locally near 20 by late on Sunday.

To put this into perspective, strong tornadoes can occur with STP's near 1 or 2. STP's in the 10 to 20 range is VERY RARE and should serve as a real eye opener as to the potential with this Easter set up.

Timing the storms

While storms will be ongoing in the morning on Sunday with the potential for large hail and a few tornadoes, the main event looks to hold off until later in the afternoon as we head into Sunday evening. These storms will likely persist well overnight Sunday night as a line or broken line of storms known as a QLCS.. quasi-linear convective system with the potential for tornadoes and damaging winds into Monday morning.

Summary

I think Sunday will be a rough day for the south with the potential for all modes of severe weather including tornadoes... some potentially violent with long tracks. As data continues to come in, I think there's a really good chance that parts of the region get upgraded to a HIGH RISK.

It should be noted that while the main the highest risk area remains across the South, a system as large and powerful as this should be monitored closely as the threat for severe storms will extend well north through the Tennessee and Ohio River Valleys depending how the details pan out and will carry with it conditional risks based on instability and heating.

I will be monitoring closely as we head into your Easter Sunday and will provide LIVE COVERAGE on my youtube channel as needed. This entire systems pays a visit to the Northeast on Monday where high winds are likely. High Wind Warnings and High Wind Watches have been posted.