The Severe Weather Outbreak of January 16, 2022

A potent setup began to take shape in the pre-dawn hours to the west of the Florida peninsula. This was associated with an area of  low pressure  working through the Florida Panhandle. Ahead of the advancing  cold front,  a  squall line  had developed over the Gulf waters. 

As storms were approaching, an  upper-level trough  lagging behind the surface feature was also  propagating  across the southeast states. This setup favored intensification of the surface low. With the  jet stream  rounding out the bottom of the trough, the central and southern portions of the Florida peninsula were placed in a favorable region for upper-level  divergence  (favoring ascent) and 300 mb (~30 kft) winds of 40-60 kts.

The 500 mb (~18 kft) flow yielded similar support with  positive vorticity advection  (PVA) - a mechanism for large-scale ascent - inferred from this setup. The flow also remained elevated in the 40-60 kt range.

Closer to the surface at 850 mb (~5 kft), southwesterly flow was transporting additional low-level moisture from the tropics over the state. With more of a southerly component when compared to 500 mb, this supported a  veering profile  with  Warm Air Advection (WAA) . This also implied that  directional shear  was present, with storms having additional  streamwise vorticity  to work with.

The 12Z  NWS Tampa Bay sounding  further alluded to the aforementioned potential for severe  convection . The balloon was launched just before the convective line arrived at the office, providing a powerful snapshot into the state of the atmosphere. A sheared and saturated environment with large-scale forcing mechanisms for ascent existed to support and sustain convection.

Additionally, surface-3 km  Storm-Relative Helicity  (SRH) values were near 500 m ² / s ² . Further supporting the severe potential was the clockwise-turning  hodograph . The shape of the hodograph was consistent with the high SRH values in the sounding. Combined, this created an elevated risk for both  supercell thunderstorms  and  tornadoes . The limiting factor was  instability . As analyzed in the 12Z sounding,  lapse rates  were on the weak side, especially in the mid-levels where they were only 4.5 °C/km. Additionally,  Convective Available Potential Energy (CAPE)  values were weak, with only 200-300 J/kg (Joules/kilogram) present. 

However, previous studies have shown that in a cool season pre-frontal environment, similar to the one that existed on the morning of the 16th, CAPE is not a significant limiting factor. With 200-300 J/kg  MLCAPE (Mixed Layer Convective Available Potential Energy)  present, combined with the forcing ahead of the front, the limiting factor of weak instability was not enough to prevent strong updrafts from developing. Additionally, SRH values were high enough that updrafts didn’t need to be very tall to spin. In fact, the entire setup is a rather textbook example of a high shear, low CAPE environment that often accompanies severe weather outbreaks across the southeast United States.

The  Supercell Composite Parameter (SCP)  yielded values as high as 4, which further supported an environment capable of supporting supercells, especially for coastal sections of southwest Florida.

 Significant Tornado Parameter (STP)  values were as high as 1 right at the immediate coast. Based upon previous studies, most EF2 or greater tornadoes are associated with values greater than 1. Thus, the STP alluded to the possibility of strong tornadoes.

Storms that developed near Southwest Florida (SWFL) underwent the strongest intensification. Despite being weak overall, the slight improvement in instability is what contributed the most to the higher supercell and tornado parameter values. An axis of 500 J/kg  Mixed Layer CAPE (MLCAPE)  was analyzed at 12Z just off the coast of SWFL, with 1000 J/kg  Surface Based CAPE (SBCAPE)  and  Most Unstable CAPE (MUCAPE) . These last two CAPE values go into the  STP  and  SCP  parameters respectively. There was no  Convective Inhibition (CIN)  either to suppress updrafts. Thus, these storms developed in a more favorable region with higher CAPE and could be sustained by the highly sheared environment, as they moved onshore.

Squall lines are not that uncommon in the cool season across West Central and SWFL. With squall lines come an increased risk for tornadoes. Climatologically, the probability of seeing tornadoes in West Central and Southwest Florida increases through the month of January. When compared with portions of the central Gulf Coast and Southeast, the probabilities become almost equal.

However, tornadoes in January are still rare, especially in SWFL. Of the 173 tornadoes that were recorded between 1950 and 2020 in Charlotte (57) and Lee (116) Counties, only 12 occurred in January.

Of the 12 January tornadoes, only 5 were EF1/F1 or greater. June and September have also each seen 5 tornadoes of similar intensities. These are the three months with the most recorded EF1/F1 tornadoes or greater.

When broken down by season, strong tornadoes are also least likely in the winter months across Charlotte and Lee Counties. However, the dataset is small.

The amount of tornadoes that occurred in southwest Florida on January 16, 2022 surpasses that of any previous event dating back to 1950 when records began.

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