Severe storms and tornadoes during the fall are simply a way of life here in the Tennessee Valley and much of the Southeast. Our area’s tornado season begins in November and runs through May, although those storms can occasionally start as early as October and can sometimes last into parts of June. November tornadoes can sometimes be just as violent and deadly as the tornadoes we see in the heart of spring, and one clear example of that is the November 15, 1989 F4 tornado that struck portions of Huntsville, Alabama. This tornado would not only change the lives of the people it directly affected, but it forever changed the way severe weather warnings are handled in our area, and it would spur forward monumental revolutions in the way severe weather is detected and tracked in the broadcast meteorology industry.
Basic stats about the tornado:
- Fujita Scale Rating: F4
- Active from around 4:30 PM to around 4:50 PM
- Path Length: 18.5 miles
- Path Width: 880 yards (1/2 mile)
- Fatalities: 21
- Injuries: 463
- Damage cost: $100 million (1989-era US Dollars)
The weather pattern in the mid and upper levels of the atmosphere heading in to November 15, 1989 was one that was definitely reminiscent of what we have seen with other significant severe weather outbreaks in our area before and sense. A large scale trough of low pressure at 500mb (roughly 18,000 ft above mean sea level) was situated over the middle of the nation with broad southwest flow ahead of it across much of the Tennessee, Ohio, and Mississippi Valleys and into the Southeast. That trough would continue to deepen (intensify) through the day and into the evening as it approached our area, and it would begin to take on a bit more of a negative tilt. This would be brought about by a smaller scale disturbance in the mean trough’s flow situated over eastern Colorado into western Kansas that would dive southeast into southern Oklahoma and western Arkansas by evening, tightening the height gradient (pressure gradient but above ground) in the trough and intensifying an already favorable 50-60 knot 500mb jet streak over north Texas to Arkansas to the 80-90 knot range by early evening as it spread across the Tennessee Valley. This intense jet stream wind energy would provide a potent deep-layer wind shear environment that would be favorable for supercells and intense long-track tornadoes during the afternoon to evening hours over a large area near and east of the Mississippi River.
In the lower-levels of the atmosphere, a sharpening trough of low pressure at 850mb (roughly 5,000 ft above mean sea level) was situated from the Great Lakes down to north central Texas with a cold front associated with it. Through the day, a closed low pressure area developed along that front and pressure trough and lifted northeastward into the Great Lakes. In response to this, a 50 knot 850-mb low-level jet developed over the warm sector through the day, rapidly pulling warm, humid, unstable air northward from the Gulf of Mexico well north into the Tennessee and Ohio Valleys and rapidly strengthening the low-level wind shear over a large area through the day.
At the surface, a strong low pressure system along the eastward-moving cold front would shift in to northern Indiana by the early to mid afternoon. Strong southerly winds of 10 to 25 mph ahead of this could front would bring warm, moist air northward through the area. By 2:00 pm local time, temperatures through much of the Tennessee Valley and Deep South were well into the 70s with a few isolated areas in the lower 80s. Dewpoints where into the mid to upper 60s across a large area of the Southeast. Combined with the cold, dry air aloft, this made for a very unstable atmosphere from the Ohio Valley down to the Gulf Coast ahead of the advancing cold front. By the mid to late afternoon, smaller scale areas of low pressure (known as meso-lows) would develop along the cold front, with one over southern middle Tennessee and another near the Ohio River. These small-scale low pressure areas would locally back the surface winds sharper to the south or southeast just ahead of them, further strengthening the low-level wind shear and spin in the unstable atmosphere over the area.
Meteorologists knew that November 15, 1989 had the potential to be a major severe weather day. Near midnight going into the early morning of the 15th, the National Severe Storms Forecast Center in Kansas City, Missouri (what became the Storm Prediction Center and moved to Norman, Oklahoma in the late 90s) placed all of Alabama, almost all of Mississippi, much of Tennessee, western and central Georgia, and the Florida Panhandle in a somewhat infrequent “Moderate Risk” (Level 4 of 5 on today’s scale) of severe storms for the day, and the outlook mentioned the possibility of a few significant tornadoes across the area. After morning surface and upper-air sounding data came in, it was becoming more apparent that a major severe weather outbreak would potentially take shape later in the day, and roughly around 9:30am, the outlook was upgraded to a rare “High Risk” (Level 5 of 5 on today’s scale) of severe storms from the Ohio River straight down to the Gulf Coast. This rare “High Risk” issuance was continued on the afternoon update that was issued around 2:00 pm. The “High Risk” area was actually expanded as far east as the western Carolinas on that update due to an expected continuation of the threat eastward into the evening and nighttime hours. The High Risk level was used because forecasters saw increasing confidence of a major severe weather event during the afternoon and evening hours with the potential for supercell thunderstorms that would be capable of a few long-tracked potentially violent tornadoes. At 12:01 pm local time, the NSSFC issued a Tornado Watch valid until 8:00 pm for a large part of north and west central Alabama, middle Tennessee, and northeast to east central Mississippi. This tornado watch carried the fairly uncommon “PDS” wording, meaning that this was a Particularly Dangerous Situation with the potential for a few long-tracked strong to violent tornadoes. Only about 3% of all tornado watches get the PDS wording. They are fairly rare in the overall scheme of things.
Not too long after the tornado watch was issued, the capping inversion layer in the mid-levels of the atmosphere began to weaken over the area ahead of a squall line of thunderstorms that was moving in from the Mississippi River Valley area of west Tennessee and north Mississippi ahead of the cold front. This allowed a couple of individual supercell thunderstorms to develop over northeast Mississippi and move up into northwest Alabama. Additional individual supercell thunderstorms developed deeper into the warm sector over east central Alabama into western Georgia. Despite a couple of lower-end tornadoes with the east Alabama supercells and a couple of tornado warnings with the northwest Alabama supercells, storms were mostly behaving going into the mid afternoon when compared to the forecast. A bow echo along the squall line moved into northwest Alabama during the 3:00 pm hour and produced some isolated reports of wind damage and hail over the general Shoals area. So far, storms were not living up to the High Risk forecast and PDS Tornado Watch that had been put into place.
During the 4:00 pm hour, the squall line continued to march eastward across the Tennessee Valley as the isolated supercell activity continued to move northeastward toward the general Huntsville metro areas. NWS had switched over to issuing severe thunderstorm warnings for both the supercell activity and the line since there had been no confirmed tornadoes with any of the storms since they started to develop a couple hours beforehand. Approaching 4:30 pm, the advancing squall line began to catch up to the lead supercell that had been moving northeastward through Lawrence and Morgan Counties of Alabama toward the Huntsville area. From what we think we understand now given the limited data we have to look back on, the gust front of rain-cooled air from the line of storms may have helped enhance the rear-flank downdraft in the back end of the supercell as the supercell merged into the line. This likely helped jump start the process of the supercell finally producing a tornado, because it’s often interactions with small-scale boundaries and other small-scale processes that actually get the storms to produce a tornado, even on a day when the overall large scale setup is very favorable.
Around 4:30 pm, the violent F4 tornado would form near the Huntsville Airport and move quickly northeastward through the southern side of Huntsville during afternoon rush hour, through the Jones Valley area, and into the Brownsboro region before finally ending its destruction. Along that 18.5 mile track, the tornado would flatten homes, businesses, schools, and other neighborhood buildings; and it would go on to kill 21 people and injure another 463. Unfortunately, the tornado happened before Doppler Radar was made available as part of the modernization of the National Weather Service. There was radar data available to track the storms, but it was lower resolution and outdated technology from the WSR-57 and WSR-74 eras, and it did not have the Doppler capabilities that let us see wind movement inside storms. This means that meteorologists had no real way of telling that the storms they were seeing on radar were rotating. This, when combined with the storms never producing any tornado activity in their history beforehand across north Alabama, led to there not being a tornado warning issued in time for the start of the tornado’s damage. It was not until 4:35 pm or after (a few minutes after the tornado had started doing damage) that initial reports of a tornado and/or damage started coming in to area TV and radio stations and the National Weather Service. A tornado warning for the storm was not issued until 4:39 pm, nine minutes after the tornado first started. In today’s era, it’s hard to fathom a circumstance where that would be anything other than inexcusable given the technology we have today, but that technology wasn’t around in 1989, and meteorologists were simply doing the best they could with what limited data and information they had.
That tornado in 1989 would spur changes that would revolutionize the way severe weather is detected and covered by meteorologists today. Bob Baron was chief meteorologist at WAFF-TV 48 in Huntsville at the time of the tornado, and he was on air with coverage that afternoon. Talking over the years about his experiences from that day, Bob has said that he was left feeling that the TV weather industry had a bunch of flashy weather “gadgets” at the time, but no real TOOLS to use to track storms and disseminate timely and accurate severe weather information. He sought out to change all that and ended up starting the company Baron Services in Huntsville going into the early 90s. Bob Baron has since retired from his active role in the company but still actively heads up his non-profit Baron Critical Weather Institute that plays an active role in deploying weather cameras and instrumentation across the state of Alabama and adjacent areas. The Baron company was responsible for creating the industry gold standard storm tracking programs of FasTrac and VIPIR in the 90s that set the bar for how severe weather is detected, tracked, and that information is presented in the broadcast industry. From storm tracks with times of arrival, live lightning data overlaid onto radar mapping, street-level radar storm tracking, automated storm tracking and wind shear detection algorithms, and so much more, Baron has paved the way for us to do our jobs efficiently and thoroughly so that we as an industry can give you the information you need to save your life and the lives of your family when weather turns dangerous. Now within the Lynx system, all of Baron’s storm tracking power is combined with a powerful data visualization and graphics engine that meteorologists can use to not only track severe storms, but give you the most accurate forecast of the day-to-day weather possible. Out of a love for Baron’s long-standing legacy through the years and their flagship systems of the 90s and 2000s, we still call the storm tracking and radar portion of their software “VIPIR” here at the Tennessee Valley Weather Center, but we utilize that Baron Lynx technology to bring you accurate and dependable weather information right here every single day!
Included images courtesy of NWS Huntsville, NWS Birmingham, and Baron Weather in Huntsville, AL