Intro thank you to Aura for sponsoring this video I'm in L pla Maryland a busling community about 30 minutes south of Washington DC but closer to an hour if you commute to the West lies the pomac river and to the east the Chesapeake Bay of the Atlantic Ocean despite being this far east the small town of 10,000 residents has been the target of two violent tornadoes November M 9th 1926 and April 28th 2002 both of these Twisters were deadly f4s in fact there have only been 6 F4 tornadoes to occur north and east of LL Worcester in 1953 West Stockbridge in 1973 Windsor loocks in 79 hamen in 89 and greaton barington in 1995 although the 1926 tornado was more deadly and came without warning the 2002 tornado that carved a path directly through the town has its own significant place in severe weather history occurring well outside of the climatologically favored area for April tornadoes the supercell traveled nearly 300 Mi across the rugged terrain of the Appalachian Plateau of Kentucky and West Virginia before finally producing a tornado as it traversed the pomac over 6 hours after it initially formed while preliminary surveys rated the tornado as F5 further analysis of the $100 million damage path gave the tornado its final and slightly weak rating of f4 today we'll analyze the unstable synoptic environment situated in the Mid-Atlantic and Central Appalachians follow the supercell from birth in Kentucky to death in the Atlantic and analyze the incredible damage produced just 30 minutes south of the nation's capital and visit the town today a place that has changed dramatically in the past 20 years and also get stranded there let's Eastern Climatology dive in now if you've watched this channel for a period of time or are familiar with severe weathers you already know the typical synoptic setup needed for tornadoes surface moisture drier air Loft strong jet stream creating wind shear but to get these ingredients to overlap this far east in the United States is pretty rare and tornado climatology Maps reinforce this point a glaring obstacle right off the bat is this little mountain range called the appalachin mountains stretching 2,000 mi from New Finland to Alabama it provides some resistance to eastwest moving weather systems while tornadoes do occur in this area they do so much less frequently than glaciated areas to the immediate West the Appalachian Mountains Are tall enough to disrupt lowlevel Jets or transports of moisture from the Gulf of Mexico at the surface when storms move into this area they are less prone to producing tornadoes but that doesn't mean it's impossible on April 2nd 2024 a lone supercell traveled across the Appalachian Plateau into Central West Virginia and produced a tornado a few miles east of the New River Gorge but then quickly dissipated half an hour later the environment directly to the West over Kentucky and Tennessee was much more favorable for supercells and tornadoes with decent Cape abundant moisture at the surface and strong wind shear and had prompted a moderate risk issued by the National Weather Service another classic example of a similar setup involving Appalachian tornadoes is May 31st 1985 when a violent and unstable atmosphere existed over Northeastern Ohio and western Pennsylvania supercells fired in the mid-afternoon paraded East and dropped several violent tornadoes in the central Pennsylvania National Forest before dissipating late Into the Night a third example for good measure is April 27th 2011 when countless supercells formed in Alabama and Tennessee then meandered through the appalachin mountains in fact one supercell produced a violent tornado within the Smoky Mountains the most rugged terrain east of the Mississippi the big point of emphasis here is that you have a favorable environment to the west of the mountains where the storms initiate and then they move into the mountains where they eventually weaken but what about the opposite what if a storm initiates in the Appalachian Mountains traverses the entire range strengthens and then produces a tornado what atmospheric Dynamics have to be at play in order for this to happen well enter April 28th 2002 before we get into this I want to talk about something really important have you seen what's been going on the past few weeks hackers on the dark web reportedly stole and released the records of 2.7 billion people including full names addresses and Social Security numbers just a few weeks prior I was notified that all AT&T customers including myself had their text messages and phone calls stolen by a third party thankfully I have been actively using Aura for a while now and they let me know immediately when they found my email and password in a data breach on the dark web I was then able to change all my passwords that same day and that peace of mind is Priceless Aura is the company that protects all of your personal information in this dangerous digital world and it truly is the One-Stop shop for 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ofof began diving down over the plains one of these Lowe's moved over Missouri on the 21st with a jet streak accelerating northwestward over Illinois warm moist air at the surface made the atmosphere very unstable and by the late afternoon a line of supercells fired to the south of St Louis one of these storms produced an F3 tornado that went through Fairfield Illinois killing one man in his mobile home this series of pictures was was taken by Mary Hurley from her Farm it's one of my personal favorites including this image of an old basketball hoop with the tornado looming behind on the 24th another low pushed South through the Upper Midwest and supercells fired along a cold front again in Missouri one of the southeast drifting supercells produced an F4 tornado on the southern edge of the Mark Twain National Forest over the next couple days a trough of low pressure remains stagnant over the Eastern Pacific but finally on the morning of the 27th a smaller embedded trough surged Eastward across the Great Basin and a surface low began forming over Colorado now a setup like this in late April would usually be caused for concern for the central plains in Missouri in fact let's compare weather charts with those of March 13th 1990 the day of the hon Kansas F5 tornado among many others on the 500 mbar map we can see the low Aloft is clearly much stronger on March 13th and the trough flowing around the low exhibits a much larger amplitude but at least in this level of the atmosphere both jet streaks or fast moving bands of wind within the jet stream are moving it around 70 to 80 knots now let's compare Surface Maps both show Surface lows developing over Eastern Colorado with April 27th being considerably stronger than March 13th but the biggest difference between the two take a look at the Northeast in the Mid-Atlantic on April 27th an expansive cold front in dry air mass was situated over the entire Northeast blocking warm Gulf Air from streaming northward on March 13th that low-level jet was unimpeded and made the atmosphere extremely unstable in the central plains now this setup could still very well produce severe weather it all depended on where that warm front was going to be later in the day model suggested that the warm front would move considerably further Northeast throughout the afternoon and so the Storm Prediction Center issued a moderate risk for most of the Corn Belt areas in the warm sector would likely see discre storms late in the day that would congeal into a Squall line if you watch my video on the Huntsville tornado of 1989 then you might remember how convective mode works you can click up in the corner if you need a refresher the bulk Shear Vector when aligned with the initiating boundary in this case the cold front was about 45° which meant that storms would start off as discreet then slowly form a line as they marched East ahead of the cold front but notice here at around 900 p.m. central temperatures in the warm sector in Missouri were still only around 60° the main warm front was still draped across the Ozarks extending to the southeast tornado watches were issued and canceled across Western Missouri and Iowa as meteorologists watched the warm front surge further north discret storms did Fire And while a few looked impressive including one supercell with a massive Hill core north of Jefferson City none of them actually produced tornadoes throughout the overnight hours the low-l jet was now well established and the influx of into the Mississippi and Ohio river valleys aided in the formation of a line Echo wave pattern strong individual downdrafts within the line of storms were causing them to bow out and give the line This wavy shape a tornado watch was issued for the southern portion of the line but again no tornadoes actually occurred now while these storms were currently in an unstable environment they would run into several issues within the next few hours one the storms were headed for the rugged terrain of the Appalachian Mountains which as we established earlier often disrupt the thermodynamic processes within a thunderstorm causing it to weaken two directly to the east lay an extensive swath of cloud cover and Rain you see when a shower thunderstorm moves through an area especially if that rain is widespread it uses up some of that potential energy in the atmosphere making it more stable and less prone to Future severe weather remember with cape if you look at the equation you're essentially looking at temperature differences with respect to height and and widespread rain can minimize that temperature difference so does this mean that the severe weather threat was just over for the day no and this is where we get to talk about air mass recovery the process that describes how an unstable atmosphere which has been stabilized by convection can then destabilize again making it Prime for severe weather later in the day with a lot of severe weather events on day one you'll get leftover showers and thunderstorms from the evening before which move through the morning of day one and they keep that surface temperature cool what meteorologists often look for with air mass recovery is sunshine because the sun will heat the ground in the air above it and now that warm air can rise into thunderstorms you don't need a ton of widespread Sunshine either a couple hours of mostly sunny or even partly sunny skies can often be enough to fuel an outbreak while the morning storms were going to die out as they hit the appalachin meteorologists at the Storm Prediction Center expected Sunshine later in the day in Virginia and Maryland and along with a surge of Gulf moisture and approaching shortwave trough were enough to Warrant the upgrade of a slight risk to a moderate risk of severe weather by 11:00 a.m. Storms Fire and... split? eastern storms were already firing along the cold front in Western Ohio surface temperatures and dup points were both in the low 60s shortly after initiation a tornado watch was issued for the entirety of Ohio but the Storm Prediction Center acknowledged that tornadoes were not the main threat here the cold front was racing so fast across Ohio that the convective mode would likely transition to linear as the storms progressed across the watch area making damaging wind inhale the main threat now as the cold front moved Eastward warm air surged into the central appalachin Sun for the past few hours really helped air mass recovery in the region and Cape was soaring above 2500 Jew per kgam with decent wind shear in a discret storm mode lawn track violent tornadoes were very possible if that rugged terrain from the Appalachians didn't interfere with the dynamic processes of those thunderstorms and so a PDS tornado watch was issued at 1:21 p.m. for the entirety of West Virginia now I want to follow the path of one cluster of supercells in particular that formed to the east of Lexington Kentucky at around noon Eastern as these storms progressed across the appalachin plateau into West Virginia you'll notice an interesting Behavior several of these storms split into two separate storms similar to how animal and plant cells divide this is actually a fairly common occurrence in fact the change in wind speed and direction with height or wind shear which is what causes these updrafts to rotate in the first place can actually dictate the life cycle of each of the individual storms after the split happens but why does that split happen in the first place well wind shear causes vorticity in the horizontal plane and in order to get a thunderstorm to rotate you need that horizontal tube of rotating air to tilt into the vertical air that rises rapidly up from the surface is the mechanism that stretches the rotation vertically it's like laying this Slinky on a flat surface picking up the middle and lifting it now on either side you have clockwise spinning Rising air and counterclockwise spinning Rising air when a downdraft forms in the thunderstorm due to Falling precipitation it can pull this tube of spinning air downwards and the North and South updrafts move further apart a additionally when an air parcel is rotating and Rising it's pushing its way upwards through other air molecules causing higher pressure aoft and lower pressure in its wake this vertical pressure gradient Force also AIDS in the development of new updrafts on the opposing sides or flanks of the original one so what happens to these two new thunderstorms after the split well the best way to visualize this is using a photograph which Maps out wind speed and direction by height and then all of the points are connected with a line let's take a look at a straight photograph at the surface the wind is 7 m/s out of the southeast and then slows down to 5 m/s 1 km above the ground then as you go up wind speeds increase and become more Westerly hitting maximum speeds at 40 m/s or near 100 mph this right here is the mean wind Vector it is the average speed and direction of the wind between the Surface and 6 km you would expect storms that form in this area to more or less follow the speed and path of the mean wind Vector this is the bulk Shear Vector it shows the general direction of the wind shear between 0 and 6 km now after a supercell splits in two the leftmost storm typically moves to the left of the mean wind vector and the Right Moving storm typically moves to the right of the mean wind Vector these storms are named left mover and right mover respectively in a situation where you have a straight photograph the left and right movers are equally strong while the right mover updraft spins cyclonically and the left mover anticyclonically with a curved photograph below 3 km the right mover will be the dominant storm and the left mover will weaken over the next couple hours and this makes sense the low-level curve in this Photograph means strong southernly winds at the surface or a low-level jet are feeding the storm enhancing the southern facing updraft the final scenario where the photograph Curves in the opposite direction between 0 and 3 km is quite rare and in this case the left mover would be the dominant storm but think about this for a second this would imply that the warm moist air at the surface is streaming Into the Storm from the North and the source of moisture in the United States is the Gulf of Mexico which is by default the southernmost part of the United States you need an extremely odd synoptic situation where a large amount of surface moisture is displaced very far north but getting blown back to the South clearly in the case of our supercells over West Virginia irginia the right mover was typically the more dominant storm and continued on a trek east Southeast throughout the warm unstable environment at 305 p.m. a tornado watch was issued for most of Virginia DC and all of Maryland followed by a mesoscale discussion regarding the watch area Maryland and DC were just now Storms hit the mountains! seeing sunshine and would continue to do so until the supercells west of the managa Hala National Forest got there that is if they got there while they looked impressive on radar they had yet to cross the 4,000 ft Ridges of the mananga Hala National Forest a near 3,000 ft elevation change over a very short period if these storms survive the next 60m Journey they would be in a prime environment for tornadoes and the storms did indeed make the TR but weakened noticeably as a result by this time around 4:30 p.m. the synoptic environment in Virginia had changed dramatically as the shortwave trough aoft approached the area a strong low-level jet developed bringing in a surge of low-level moisture into the region increasing wind shear and instability these winds likely converged in the shannona valley as the southernmost supercell approached and wouldn't you know it it finally produced a tornado a short-lived F2 that lifted before the storm crossed the Masson range at around this time Steve macheski was on a first class flight from Philadelphia to Atlanta when he saw the Super Cell from the airplane window and caught this footage of the incredible updraft being a research meteorologist for the FAA he knew exactly what he was seeing as the storm continued to the east on the now flat terrain it cycled several times producing funnel clouds over fakier County but didn't have enough juice to touch down before the downdraft choked out the inflow despite Supercell crosses Potomac this the National Weather Service kept issuing tornado warnings out ahead of the storm until 6:30 p.m. the storm was now directly over quano approaching the pomac and it had failed to produce another tornado despite cycling several times the National Weather Service chose to issue a severe thunderstorm warning for Charles County Maryland just to the east of the pomac and it was a bit puzzling why the surface assessment gives us a couple clues the hook like appendage or hook Echo had dissipated over several volume scans prior to the severe thunderstorm warning being issued two forecasters at the office were tasked with issuing warnings and they were busy issuing severe thunderstorm warnings for northern Maryland as the storm crossed the pomac they were also worried about too many false alarms wanting to minimize their false alarm rates and in this case the decision proved to be fatal additionally storms in this synoptic environment have a tendency to strengthen when crossing the poic it's a 1 and 1/2 mile wide body of water being cooler than its surrounding environment and supercells love producing tornadoes near temperature boundaries and at 6:56 p.m. a tornado touchdown near Marbury Maryland moving east Southeast golf ball-sized Hill was dropping just to the North in Indian Head the thin cone tornado moved through heavily forested area flattening a swath of trees into the community of Ripley where it damaged several homes at f2 intensity at this point people in the community of Lea 5 miles to the southeast could see the tornado in fact if you look at this image taken from the quailwood subdivision it looks like something out of Kansas That rain-free Base is just textbook super cellular structure at 7:00 p.m. the tornado report was relayed to the National Weather Service and at 7:02 a proper tornado warning was issued Lea had about 3 minutes to act now this was not Lea's first dance with a major tornado in 1926 an F4 hit the LL of school killing 12 children and five others instantly since then the town had grown substantially the cista medical center was established in the 1930s to serve the residents of Charles County in 1940 the Harry W Memorial Bridge was completed connecting Southern Maryland to Eastern Virginia for the first time increasing traffic to the community Sirens were installed in the 1960s but they were mainly used to alert of fires and were not operational for severe weather by the year 2002 6,500 residents lived in the community and many of them were standing outside staring at this twisting condensation funnel heading right for them and that's another thing too the condensation funnel was invisible visible about halfway up it didn't look like some menacing F4 tornado it appeared fairly weak until it hit the quailwood subdivision outer walls of homes along Morgan's Ridge Road collapsed as the multiple vortices churned a path parallel to the street maximizing destruction homes were not anchored to their foundations well in this area and suffered catastrophic damage as a result at about this time Jeff posie was standing on Maple Avenue looking Northwest at the approaching tornado the debris field was enormous even though the condensation funnel wasn't visible this water tower would no longer be standing in a mere 60 seconds about a mile to the north of downtown was the Lea Village Center containing a Food Lion AutoZone and Family Dollar and being a Sunday evening many residents were running some last minute errands for the work week ahead Tom Albritton and Richard King took the following two photographs of the tornado the second being the iconic image featured in the Maryland Independence the thomassin were also near the Food Lion and took this footage as the Twister struck downtown first to go was the Archbishop Neil school which thankfully was not in session on a Sunday night the sisters in the convent survived having gone downstairs when they heard the approaching tornado the LL shopping center a block away looked like a war zone the CVS sign was leaning to the east wearing Twisted sheet metal from various other buildings the roof was lifted clean off the KFC and the United Methodist Church the volunteer fire department nearly escaped the 200 mph winds the water tower did not and would not stand again upon falling it released hundreds of gallons of water flooding three neighboring homes one of the few places F4 damage was observed was two adjacent homes downwind of a lumber yard a steel and brick structure engineer Tim Marshall observed that debris from this lumber yard was sent flying through these two homes locally intensifying the damage Matt Ament was with his uncle and his dad on North Wiltshire Court as the tornado was churning through downtown L pla Matt grabbed his camcorder and started filming the iconic footage that you've likely seen before right by here yeah no need to shift now you keeping it uhoh and then the golf ball siiz tail begins to fall while the freshly waxed third gen 4Runner sits exposed in the driveway hail it's hailing jeez oh flip oh wa Java get in here come on come here holy it's coming from that way and a Ford Mustang I suppose by this time a debris ball was clearly visible on radar as well as the massive Hil core on Hawkins gate Road a man was standing inside his newly constructed home as the tornado hit killing him instantly as the tornado continued to tear Southeast towards the Chesapeake Bay Andrew Gardner positioned himself at the corner of Solomon's Island Road in flag Pond's Parkway looking north and east he captured this footage of the tornado as it approached and crossed into the bay becoming a water spout the electric transmission tow as you see here Supply power from the Calbert Cliff's nuclear power plant less than a mile to the tornado South disaster was averted once over the Chesapeake Bay a second satellite tornado touchdown likely a result from the secondary circulation on the southern side of the mesocyclone the tornado continued into Eastern Maryland staying in mainly Royal forested areas for the duration of its life chaos ensued in downtown L PL as the sun dipped below the Horizon ambulances rushed down congested route 301 to rescue Shoppers from collapsed buildings doe in part to its proximity to Washington DC the rescue and cleanup operations that took place were fast and furious with 400 structures destroyed of which 165 were businesses debris was littered everywhere City officials were reportedly frustrated with FEMA who looked to minimize the cost of recovery efforts when the city just wanted to clean up fast and figure out the expenses later on that paid off as the town was 98% clean of debris within 12 days there has not been a violent tornado this close to the DC Metro since the L pla incident and if it happened again today thousands more would be affected this part of the country is experiencing huge population growth and L is now twice as large and now I'm standing a top the hill on Charles Street thinking about what it must have been like to watch the Tornado approach town along Firehouse alley exists the star Memorial Garden in memory of those who lost their lives in both the 19 26 in 2002 tornadoes my girlfriend thought we should make a contribution to the garden and so we left this little guy I think he fits in pretty well if you guys want to learn more about the events that unfolded in Le PL on that day I highly recommend you check out this book hope triumphs over chaos by Anthony Pilla he includes dozens of stories of survivors and the book is just filled with pictures you're not going to find anywhere else I did find a couple factual errors whether it be an addresses Ron or the direct that a picture is taken is incorrect but overall this is a fantastic read if you want to learn more about supercell Dynamics and how storm split and you're a little bit more mathematically inclined check the link in the description there are a couple research papers that I think you're really going to like also weather boox has a mailing address now if you want to send me any weather related items you are welcome to I'm looking forward to seeing what you got hope you guys are enjoying summer and I will see you soon [Music] and we got a p301 cylinder 1 misfire in Maryland so that's pretty cool