March-April 1997 STORMTRACK features Chase Climatology, Tornadoes in Tallgrass Prairies, Chase Documentation, Dave Hoadleyís On the Way, and the Barfield-Murfreesboro, TN tornado.
LESSON #1: DONíT TURN YOUR BACK
I. COMMENTARY by Tim Marshall
A new chase year has begun -and so begins the teachings of mother nature. Her first lesson in 1997 seemed to be a repeat of the same lesson she has taught year after year. The date was April 10th. A cold front had slipped through the Texas panhandle and stalled around Lubbock with a dryline extending southward along the Texas-New Mexico border. Upper dynamics were strong, however, like many early spring days, the surface thermodynamics were weak. That morning, many National Weather Service and Storm Prediction Center (SPC) discussions did indicate the likelihood of severe weather, but no one really forecasted that an outbreak of tornadoes was to occur later that afternoon. Many chasers, including myself, analyzed the weather situation and really werenít impressed. Low clouds and low temperatures prevailed in the "warm" sector. I had to run the heat in my truck during the morning while in Dallas due to the cold damp winds blowing in from the south.
As with many chase days, weather parameters didnít really come together until the early afternoon. Skies in the "warm sector" began to clear and surface heating was taking place. Deeper moisture streamed northwestward enhancing the moisture convergence maximum around Lubbock. Unfortunately for me, I could only check the 12z conditions and remained outside on job sites the rest of the day. I knew that I had violated one of the sacred rules of storm chasing: DONíT TURN YOUR BACK ON THE DRYLINE! -and was promptly re-taught a lesson. Mother Nature uses the dryline like a magician. What may appear to be the "same" weather scenario in one instance can end up being a different result the next day. I keep saying to myself that this is good as I wouldnít chase if I knew what Mother Nature had up her sleeve and was really going to do. Where would be the challenge?
What has become clear over the ages is that all the data in the world, especially model data, should be viewed only as educated guesses or "guidance". Those chasers who base their chase decisions entirely upon model data or SPC outlooks are destined to fail. April 10th was such a case. The 12z and 15z SPC outlooks were "slight risks" and the outlook area was upgraded to "moderate risk" at 19z. So, it was too late to react to this situation if you chased just moderate or high risks. I personally like slight risk days. However, I canít chase every one of them due to my work schedule. So. picking and choosing when to chase is like playing the lottery. Most of the time, Mother Nature wins.
II. CHASER NEWS
The 1997 Annual Chasers Picnic is scheduled for Saturday, May 17, 1997 at Robert Prenticesí house located at 2701 Black Locust Court, Norman, Oklahoma 73071. The party begins at 1p.m. provided there is no risk area for the plains states. Bring your own food, beverage, and best storm videotape. Anyone one can attend.
Should there be a slight risk or better (12Z outlook), the party will be postponed one week until May 24th. Other alternate dates are May 31st and June 7th hopefully to insure that we will have a picnic this year. Last minute updates, changes, or cancellations can be obtained by calling the editors voice recorder at 817-430-0517 after May 15th. Directions to the Prenticesí house are shown in the last issue. Signs will be posted off Rt. 9 and 77 directing you to Robertsí house.
Al Mollersí photograph of the Pampa, Texas tornado appeared on the front cover of Rail News Magazine, April 1997. (Ed. note: see what happens when you get a tornado with railroad tracks in it!)
The Kansas Department of Transportation publishes a brochure every month which illustrates road detour and construction activity for the state. To inquire, write: Kansas DOT, Docking State Office Building, Topeka, KS 66612-1568.
III. LETTERS TO THE EDITOR
Corey Mead cashed in on the April 10, 1997 tornado outbreak in West Texas. "I was on that (southern) storm from itís infancy along the dryline. I saw six of the tornadoes it produced, three in Gaines County, and three in Lynn County. From what I understand, that storm produced between 10 and 15 tornadoes over itís 9 hour lifetime, including one large tornado near Paducah at night. The tornadoes I saw lasted from 2 to 10 minutes, and were mainly conical in shape. I had worked the midnight public shift at the National Weather Service in Midland on April 10th. I looked at a couple forecast products and knew that it would be a good day and inserted the mention of tornadoes in the forecast discussion. Everyone else across West Texas really down-played the event until that afternoon. When I got back in the office after the chase, I looked up the 00z upper air data for the event. The one thing that really stuck out was the 40 knot winds at 700 mb over Midland and Amarillo. I am currently in the final review process with a paper for Weather and Forecasting that deals with the discrimination between tornadic and non-tornadic supercell environments. The major thing that I am seeing in my results is the large increase in 700mb wind speed as one crosses from the non-tornadic to the tornadic data set."
IV. INTERNET DISCUSSIONS (new)
This is a new column in STORMTRACK featuring interesting discussions with regard to chasers and chase forecasting. These discussions have been posted on the Internet and are presented here with minimal editing. Our e-mail addresses are as follows: Tim Marshall firstname.lastname@example.org and Tim Vasquez email@example.com
Gilbert Sebenste warns chasers about using "risk" categories to plan your chase strategy. "No slam intended for SPC (Storm Prediction Center), but for those of you who were on the "Woodward" tornado back in 1991...that was a no-risk day that was upgraded to a slight...and then a moderate risk. I chased a "general thunderstorm" risk that went slight as I left and the setup produced a supercell. And I have chased high risks that have been VERY fruitful (ie. April 19, 1996 in Illinois). My point is do your own forecast first, then look at SPC's and everyone elseís. Most days SPC nails the risk dead on, but for chasers, you can better the specifics for where supercells may occur by looking at the data yourself. I have noticed in the past two years, and especially in 1996...no matter what the risk, SPC discussions are much more focused on the type of storm (squall line, supercell, multicell, etc.) you'll get. I appreciate this and I believe it also helps the spotters a ton as well. If you must chase by the SPC forecasts, look at the discussion first (if there will be supercells, they will usually tell you where they think it has the best chance of happening), then look at the risk area, and darn the risk category itself. As long as you get a nice storm, does slight, moderate and high really mean anything to a chaser?" e-mail: firstname.lastname@example.org
Stephen J. Courton writes: "Some chasers only go out a few times a year since they don't consider chasing to be a high priority or have little tolerance for busting. However many good chase days occur during slight risk (especially in the high plains in the last half of the chase season). One of my best chases occurred on a "No Risk" day (May 28, 1994). Some chasers depend to much on the SPC outlook for their decisions. I tend to use the SPC outlook to confirm my forecast and to see if they noticed something I missed. At times I don't agree with the SPC outlook and ignore their advice. Chasers also need to remember that the SPC outlook is mainly a severe thunderstorm outlook for a period of time that also includes darkness. The quality of the forecast also varies depending who wrote it. Sometimes the outlook is detailed and sometimes it is not. If a chaser busts they should not blame it on the SPC. They should also look at the data and models and make their own forecast. The SPC outlook should be used a guidance." e-mail: email@example.com
Ed Carp writes: " I also remember that a couple of weeks ago, the evening when the NWS (National Weather Service) put out nine tornado warnings in a two hour period, that it was a "slight risk" day. As Roger Edwardís said at the last TESSA meeting, the risk assessments aren't intended to be cast-in-stone guarantees. They are indications nothing more. They are meant to guide forecasters, not really meant for general consumption. If a chaser goes out or doesn't go out, based on a DAY1 or DAY2 outlook, then I'd respectfully suggest that that chaser needs to learn a bit more about forecasting." e-mail:firstname.lastname@example.org
FUNNEL and FOTO FUNNIES
Top ten Chaser Movies which didnít make the big screen.
5. GORILLA HAIL IN OUR MIDST
6. THAT THING YOU DIDNíT DO
7. RIDGES OVER POTTER COUNTY
8. STORM TREK: FIRST CONTACT
9. CLOSE ENCOUNTERS OF THE WHIRL KIND
10. NATIONAL LAMPOONS CHASE VACATION
BRAVING THE ELEMENTS: A Book Review by Bernie Kopp
Braving The Elements - The Stormy History of American Weather by David Laskin. (C) 1996, Published by Doubleday, first edition hardcover Feb. 1996, Catalog #551.6973. Mr. Laskin chronicles the history of American weather in a relatively non-technical fashion starting with the birth of native American inhabitants to the current debate over the future of our planet and the future of weather forecasting. A rather lofty and ambitious goal for anyone and quite a challenge in only a 225 page work! Mr. Laskin includes the following chapters, 1. Native American Weather, 2. Weather In The Age Of Discovery, 3. Colonial And Revolutionary Weather, 4. Weather In The West, 5. From Proverb To Probability: Weather Forecasting in America , 6. National Weather Now, 7. The Longest Running Joke and 8. What's Happening To Our Weather?
My first concern was the last chapter which I read first! Were we in for a planetary catastrophe? Should I hug my dolphin and wait for the inevitable end of "life as we know it"? Would this be another whine from the far left fringe of pseudo science/new age political correctness?
-Surprise!- Mr. Laskin provides a very balanced and easy to read discussion on the history and evolution of how we as a country perceive and react to our weather. Many of us toil in the details and components of weather as it directly affects us as individuals. "Braving The Elements" does a good job in detailing how and why we perceive weather as a country and as a culture. Only by understanding the history of weather can we realize why we currently respond the way we do, to the forces of nature. Our current knowledge is defined by our past practices, prejudices and experiences. For a good read I would recommend this book to any student of weather!
Tornadoes in Tallgrass Prairieby Dr. Stephen R. Johnson
Powerful thunderstorms, mesocyclones and tornadoes are common and characteristic phenomena of the central plains and tallgrass prairie. I was lucky enough to be associated with tallgrass prairie in Northeastern Kansas at Konza Prairie Research Natural Area near the town of Manhattan. As a plant ecologist interested in weather effects on plants, I was curious about what impacts tornadoes might have on natural plant communities. In fact, I did witness an impact of strong winds on plants, winds generated by storms that also spawned tornadoes.
While at Kansas State University in Manhattan, Kansas, I became involved in a project to describe the effects of fire on the growth and physiology of prairie cordgrass (Spartina pectinata). This grass has very long whip-like leaves that have serrated margins that can easily slice human flesh earning this species of cordgrass the name of ripgut.
On June 30, 1993, a late afternoon into evening storm generated between seven and eleven funnel clouds in and around Manhattan. From the basement floor of Bushnell Hall, I heard the roar. Later, the sky was filled with mammatus clouds colored orange by the sunset. The next day, I visited Konza prairie to find that the four foot long leaves of prairie cordgrass had become entwined around the upper parts of stems of other plants in the wetlands. The most common twining interaction was with the common milkweed, Asclepias syriaca. This twining took up half of the total length of a single cordgrass leaf and sometimes as many as five cordgrass plants had one or two leaves physically tied to a single milkweed plant. With such clusters of tied leaves spread throughout the wetland, movement within the wetland was exceedingly difficult. One year later, on July 1, 1994, another storm produced high winds and once again the cordgrass community was "tied-up".
The tough saw-like leaves of prairie tallgrass went on to damage the leaves of common milkweed in a way that simulated the action of leaf-chewing insects. Such bound and leaf damaged milkweeds subsequently produced more fruit and less seed than milkweeds that werenít involved with cordgrass. I suggested in a paper (Prairie Naturalist 26(4):301-305) that these milkweed plants responded to this loss of leaf area by maturing more fruits in a process called the transient escape hypothesis. Hence, strong thunderstorms and tornadoes may indirectly affect the reproduction of a plant.
ON THE WAYby David Hoadley
Having now pursued the storms of the great plains for some 40 years, it is time to update my earlier Storm Track article: "Why Chase Tornadoes?" It was written 15 years ago by an enthusiastic younger guy, just starting out, who felt the need to justify the strange few to the incredulous many. However, with increased media attention, an expanding corps of chasers, and now a movie, this unusual hobby has almost become "main stream" (Even TV ads now show stereotyped chasers pursuing little battery-driven bunnies!). With the perspective of many seasons, thousands of miles, and some memorable encounters, it means something different now to go forth and test one's self in that vast, dynamic sky. And it means something more.
A veteran chaser reads the sky all year long. Fall and winter must pass --with leaves to rake and snow to shovel. However, it is not these remnants of the earth but the purposeful sky that heralds each changing season. An approaching gray-slate front, a whisky cloud seen through autumn trunks draped in color, cirrus streaks riding the jet stream, and a mantel of stratus --cloaked in gold from an Olympian sunset. These are the heralds of change. The palette of the sky is ever busy, redesigning itself in endless patterns of refracting light. Sometimes a great arcing cloud will join the Canadian border to the Gulf -- one looks up and is briefly connected to something truly large and humbling. When February's river ice finally begins to grind and crack, a chaser listens for the distant trumpet of returning geese --leading the Gulf wind north to break the sod for a sleeping sea of green.
Sometimes, when driving to the store or from work, he passes some roadside scene or hears a brief passage of music and a sudden image leaps to mind. Some forgotten stretch of Wyoming road or rural scene in Nebraska appears, and he's a thousand miles away -- in a moment of beauty and space. Forty years of crossing the plains has left a rich tapestry to draw on, memories that link another time and place.
On the way west each spring, this Virginia chaser reconstructs the landscape in his mind --as it was, removing roads and bridges, farms and orchards, cities and towns, and all the detritus of this commercial society. Once again, the covered wagon moves alongside with the rangy pioneer and his hopeful family, bouncing their wagon wheels across a new, rich earth for the first time --moving slowly, by generations, westward to a promised land.
Having driven the plains from the Dakotas to Texas and Colorado to Illinois, along interstate and backroads, through sprawling cities and the smallest one-pump towns, I still sense that pioneer spirit. Help your neighbor, build that barn, heal that child, share with others (for in that unforgiving land, you may be the next in need). Some towns change, a new store here or mall there, but the core remains. For me it is like going back through a time warp to when I was young and free, and the future was a horizon of limitless possibilities. A little older now, it is something I need to be a part of each spring -- winter's fields yielding to the root, the living earth bringing forth its bounty, and a new green crop catching the passing wind in an endless sea of waves --to a distant horizon. --to a gathering of the thunder towers. Hope reborn.
And I haven't even reached storm country.
DOCUMENTING YOUR CHASESby Tim Marshall
Each storm chase is a journey, a scientific exploration. Accurate documentation of each storm chase has made me better aware of each chase event and has been invaluable in letting me know how I make decisions throughout the chase day. To preserve the chase record, I use a small hand held tape recorder. You can buy these in most department stores for less than $50. It is an essential part of my chase equipment. I use a distinct format to record information which is broken down into four parts. I record the time, odometer reading, highway or nearest town, and remarks which involve describing specific weather features, photograph information, and radio/scanner information. Later, I transcribe these chase logs and assemble them in a notebook.
At the start of each chase, I give an overview of the synoptic situation along with the good and bad points of the days chase. I also pick the target town or area that we are going to since storms usually have not formed yet upon our departure. Along the way, I record the road number and heading at each change. Specific weather information includes documenting the sky coverage (cloudy, broken, scattered, clear), cloud types (cirrus, altotypes, cumulus types), and estimating the wind speeds and direction. Sometimes, Iíll record the temperature and wet bulb too. When closing in on a storm, I describe the peripheral cloud features like transverse rolls, lines of towers, sharpness of the anvils and their direction from my location.
Photograph information that is recorded usually involves which camera is being utilized, lens type, aperture setting, and the direction of view. Usually, I carry several camera bodies with me loaded with different film. One body may have Fuji Velvia slide film (50ASA), the other Fuji Sensia slide film (100ASA, and Fuji print film (400ASA). Lenses range from 20mm to 130mm. I also carry a doubler.
Radio and scanner information that is documented includes the local thunderstorm outlook, local weather conditions, radar reports, and any watches or warnings. In tornadic situations, I leave the recorder going constantly. This way I can hear the click of each camera shot and back track later if I missed verbally describing the time the shot was taken.
Having the recorder securely attached to you or your vehicle is a must. I have lost several tape recorders in the past that were lying loose on the seat or floor and rolled out the door when the door was opened. I know of some chasers who have left their recorders on the chase vehicle only to watch debris particles blossom in the rear view mirrors as they drive away. Thus, I have a cord noose attached to the recorder.
There are many critical chase decisions made throughout the day. From the forecast in the morning, through updates later in the day, I have learned that one should stick with the original forecast as much as possible. Also, I have learned that the most critical chase decisions are made during the early afternoon, around 2pm. The typical question that one faces is: Should I stay here or should I go somewhere else? In general, there is no right answer. I have plenty of examples of both failures and successes. On April 12, 1991, I stayed with the first supercell instead of going to a second "known tornadic" supercell. Unfortunately, the second supercell produced eight tornadoes and was clearly the one to be on. Then, on May 24, 1994, I left the first supercell to go to a second "known tornadic" supercell. I arrived to find out that the tornado had dissipated on the second supercell (and no more were produced) then learned the first storm produced an eight minute highly contrasting tornado just after I left. The bottom line is to maximize your "base" time -that is, the amount of time that you are under a rain free base!
The Barfield-Murfreesboro, TN Tornadoby Charlie Neese
January 24, 1997, is a day many people in middle Tennessee wonít forget any time soon. Several tornadoes occurred across the area including the first F-4 of the year which touched down 20 miles southeast of Nashville leveling homes, damaging businesses and changing lives. At the surface, a low pressure center was moving out of southern Missouri and into western Kentucky with a trailing cold front extending through western Tennessee and Mississippi. Ahead of the Low, a warm front was situated near the Ohio River and to the south, strong southerly winds had transported relatively moist air into middle Tennessee with dewpoints in the 50ís. At 700mb, cold, dry air was in place creating very steep lapse rates. Helicity values were running in the 250-300 J/kg range with westerly winds aloft and south-southwesterly winds at the surface. CAPE values were low, only around 600 J/kg at Nashville (BNA), however breaks in the low overcast during the afternoon increased the instability of the air as temperatures rose into the 60ís. By mid-day, the Storm Prediction Center (SPC) had placed middle Tennessee in a slight risk and BNAís forecast discussion called for isolated severe storms with straight-line winds being the main threat.
While I was preparing weather maps for that eveningís newscast, I noticed very strong storms developing just to the southwest of Nashville on our regional radar. I began monitoring statements from the National Weather Service office in Nashville and continued to watch the storms explode over middle Tennessee. The first warning for a radar-indicated tornado was issued around 3:15pm for Hickman County. Golfball-size hail was reported with this storm. Three supercells were observed on radar, two of which would become tornadic. As the storms moved east, tornado warnings were issued for Williamson and Davidson (metro Nashville) counties. While over Williamson County, funnel clouds were sighted with a report of baseball-sized hail near Franklin and golfball-sized hail covering the ground near Brentwood. Next in line was Rutherford County for which the National Weather Service issued a tornado warning at 4:22pm. One of the three storms affected the northern part of the county, while another storm to the south headed for Murfreesboro. It wasnít long afterward that damage reports started coming in from both storms. The Murfreesboro tornado touched down around 5pm outside the community of Barfield downing trees and rolling a double-wide trailer home off its foundation and upside down in the backyard. Next, the tornado struck several houses in Barfield with damage ranging from removal of roofs to blowing out walls. By this time, the tornado damage path was 300 yards wide and headed for the South Ridge subdivision. The tornado did F-4 damage completely leveling a half-dozen homes and causing substantial damage to many others. Interestingly, two homes were moved from their foundations, but remained nearly intact. Many household items, such as mattresses, chairs, clothes, washers, and dryers, were deposited in a stand of trees just downwind from the subdivision as the tornado roared northeast. From that point on, the tornado weakened, but not before causing major damage to an apartment complex and damaging several businesses on the south side of Murfreesboro. The tornado crossed Interstate 24, overturning one car and downing power lines and poles. The total path length was 6.5 miles. All-in-all, more than 100 buildings were damaged or destroyed by the Barfield-Murfreesboro tornado.
The next week, I had the chance to survey the damage first-hand and talk with a member of the National Weather Service in Nashville. While analysis of the weather situation earlier in the day didnít show tornadoes to be a big threat, once the supercells began developing, the National Weather Service and the WSR-88D did their jobs well -giving the residents of Rutherford County a warning of almost 40 minutes before the tornado touched down. The early warning and the fact that many residents were still at work and not at home were apparently the two biggest reasons no lives were lost and relatively few (15) injuries were reported. We can only hope that there is as much advanced lead time and as many lives saved during the next tornado warning!