The March 24th to March 27th, 2023 tornado outbreak.

 

The event was well telegraphed. The Storm Prediction Center (SPC) started talking about the potential for organized severe weather across the Southern Plains on March 18^th. When the system came ashore in California it brought heavy winds and flooding rainfall. As the system moved from the West Coast, the SPC kept discussing the potential and issuing additional risk areas where highlighted. By March 23, the SPC issued a Slight Risk for severe weather from Texas northeastward into Missouri, primarily for the threat of large hail. Scattered reports of large hail and damaging wind gusts were received from Texas across into the Mid-Atlantic states. As things progressed two EF1 tornadoes occurred in Parker County, Texas, during the morning hours of March 24.

As the day went on, a deadly severe weather and tornado outbreak began affecting portions of the lower Mississippi River Valley in the United States.

The atmospheric setup:

A deepening trough was quickly moving eastward. We had a strong area of high pressure sitting over the Southeast CONUS.  Out ahead of the deepening low pressure a warm front was dragging a warm moist airmass air mass from the Gulf of Mexico.  A strong jet stream aloft and strong mid-level winds created an unstable air mass over Louisiana, Arkansas, Tennessee and Mississippi; where surface temperatures were into the 80's °F with dewpoints in the upper 60's into the70's.  This set the stage for widespread heavy rainfall and severe thunderstorms.

Earlier in the day, there was dry air near the ground, with a warmer layer around 15,000 feet creating a weak to moderate atmospheric cap. This hindered strong supercells and tornadoes from developing. However, over the next few hours, the environment chanced very quickly across the Mississippi Valley. The winds ahead of the front were out of the South bringing in all that warm air closer to the surface, at the same time the jet was dropping in from the west, providing a west wind aloft. Ahead of the advancing trough, out in the warm sector, a few squall lines began developing farther south, particularly along north to south oriented prefrontal confluence bands.  These bands have to do with the prefrontal tough ahead of the cold front where wind flows inward parallel to the general flow and leads to a wind shift. The shifting winds allowed the storms to start spinning. A tornado watch was issued shortly thereafter at 5:15 p.m. CDT for portions of eastern Arkansas, northeastern Louisiana, central and northern Mississippi, and western Tennessee.

At 1:00 PM

When temperature gets warmer and the dew point get drier you get a mix layer cap. The Cap is weak, but just enough to slow down thunderstorm development.

Looking at the severe indices. To save me a lot of typing you can refer to the severe weather forecasting tip sheets to see what the sounding is showing.

3cap is 40 Jkg

Mixed layer cape 568

Holograph shows a very unorganized wind field.

SFC 1km is 61

SFC 3 km is 141

6km Shear is 40

BRN is 56

STP both of them are 0.2, A majority of significant tornadoes (F2 or greater damage) have been associated with STP values greater than 1, while most non-tornadic supercells have been associated with vales less than 1 in a large sample of RAP analysis proximity soundings.

Supercell parameters are 3

The entire sounding shows the atmosphere is unsupportive for Supercells and tornadoes. 

At 7:00 pm

The Cap is still there but it is breaking down.

Looking at the severe indices. To save me a lot of typing you can refer to the severe weather forecasting tip sheets to see what the sounding is showing.

3cap is 18 Jkg

Mixed layer cape 995

Holograph shows more in the way of an organized wind field, with much better inflow.

SFC 1km is 172

SFC 3 km is 345

6km Shear is 58

BRN is 118

STP is 2.1 and 1.4, A majority of significant tornadoes (F2 or greater damage) have been associated with STP values greater than 1, while most non-tornadic supercells have been associated with vales less than 1 in a large sample of RAP analysis proximity soundings.

Supercell parameters are 8.8

The entire sounding shows the atmosphere is supportive for Supercells and a chance for short track tornadoes.

At 10:00 pm

The Cap is gone, allowing thunderstorms to explode.

Looking at the severe indices. To save me a lot of typing you can refer to the severe weather forecasting tip sheets to see what the sounding is showing.

3cap is 91 Jkg

Mixed layer cape 1642

Holograph shows the wind field increasing quickly, with a lot of inflow and a lot of spin with height.

SFC 1km is 319

SFC 3 km is 384

6km Shear is 56

BRN is 115

STP is 3.8 and 3.1, A majority of significant tornadoes (F2 or greater damage) have been associated with STP values greater than 1, while most nontornadic supercells have been associated with vales less than 1 in a large sample of RAP analysis proximity soundings.

Supercell parameters are 12.9

The entire sounding shows the atmosphere is very supportive for Supercells and strong to violent long track tornadoes.

This increased forcing that allowed the squall lines to strengthen with discrete supercells forming out ahead of the squall line. Discrete Supercells form on their own ahead of a squall line.  Because of this they don’t have to compete with other storms or the squall line for energy. This makes these kinds of supercells very dangerous as they are capable of becoming very strong and have much better odds of producing strong violent tornadoes.  As we got into the evening a strengthening nighttime low-level jet and rising levels of surface moisture led to the development of a substantial supercell across western Mississippi. As the supercell approached the Mississippi River, a tornado started to develop. The NWS issued its first tornado warning around 20 minutes before the storm reached Rolling Fork. Then before 8 p.m., the supercell produced a tornado, the tornado started as a small cone, this intensified rapidly and soon became violent. The National Weather Service issued a rare tornado emergency warning for Rolling Fork and Anguilla, Mississippi. As the significant tornado was heading straight for them. Then at around 8:05 p.m. the tornado struck Rolling Fork, the tornado continued to stay strong to violent as it moved through Midnight and Silver City all in Mississippi.

The Tornadoes:

The Enhanced Fujita Scale (EF Scale) classifies tornadoes based on the amount and type of damage caused by the tornado. It is broken down into the following categories: EF0...Weak.....65 to 85 mph, EF1...Weak.....86 to 110 mph, EF2...Strong....111 to 135 mph, EF3...Strong....136 to 165 mph, EF4...Violent...166 to 200 mph, EF5...Violent...>200 mph

The Fujita Scale (F-scale) was replaced by the EF Scale in February 2007. The F Scale is broken down into the following categories: F0 – Light Damage (40 – 72 mph), F1 – Moderate Damage (73 – 112 mph), F2 – Significant damage (113 – 157 mph), F3 – Severe Damage (158 – 206 mph), F4 – Devastating Damage (207 – 260 mph), F5 – Incredible Damage (261 – 318 mph).

The National Weather Service in Jackson, Mississippi surveyed the damage and said, the Rolling Fork, Midnight and Silver City tornado was an EF4 with peak winds of 170 mph, a path width of ¾ of a mile, with a track length of 59.4 miles.  This EF4 caused incredible damage. The same super cell produced two subsequent long track tornadoes.

Just four minutes after the Rolling Fork, Midnight and Silver City  EF4 dissipated, a new tornado developed. This tornado struck Black Hawk and Winona in Mississippi, where is caused significant damage. This tornado was rated an EF3 with peek winds of 155 mph, the damage path was 0.7 of a mile wide at points, the track length was 29.2 miles.

The third long-track tornado, was also rated EF3 by the National Weather Service Memphis, with top winds of 155 mph, a very wide damage path up to 0.9 of a mile, with a track length of 36.91 miles. This EF3 caused significant damage across Amory, Alabamia.

The NWS issued multiple tornado emergency warnings for all three tornadoes during their lifetime.

As of this writing There have been 14 confirmed tornadoes for the 24th event.

The outbreak continued March 25 into the 27^th. There were 7 confirmed tornadoes on the 25^th, across Alabamia, Tennessee, and Georgia, including two EF2 that struck Alabama. March 26 saw 6 confirmed tornadoes over Alabamia and Georgia. Alabamia and Georgia saw three tornadoes on the 27th.