What is BTI? What Does it Mean to Me?

Storm Force 31 has one of the biggest advancements in detecting a storm’s potential in producing a tornado since Doppler radar. The BTI, “ Baron Tornado Index”  is a tool that we have in the Storm Force 31 Weather Center that helps to pin-point the storms which have the highest possibility of producing a tornado. In turn we can then provide you the viewer, with advanced warning of a possible threat allowing you to take proper precautions. In the Tennessee Valley, only one weather team has access to this critical tornado detection technology and that is the Storm Force 31 Weather Team.

The BTI is provided as a number scaling from 0 to 10. The numbering is a relative rating and this simply means the storm or storms with the highest BTI values compared to the other active storms are the ones that have a higher potential of producing a tornado. For example, a storm with a BTI of 2.2 while all others are around zero would be the storm with the highest potential relative to the others in producing a tornado. In other cases, many of the ongoing storms may have low BTI values of 0 to 3 while a few may have BTI higher values such as 4s, 5s or even higher. These higher BTI rated storms would be the ones with the highest threat for producing a tornado.

Like many other tools available to meteorologists such as radar imagery and Doppler wind imagery, the BTI assists us in determining the most dangerous storms and those that may produce a tornado. The BTI is not a guarantee. However, it has proven quite reliable and as a result has become extremely useful in providing additional advanced notification of possible dangerous storms giving you the viewer additional warning time and in turn potentially saving lives.

How did the BTI Perform During the Recent Saturday, March 28, 2009 Severe Storms?

As we have noticed in previous severe weather events, the BTI has become a reliable and useful tool and this recent event was no exception. The severe storms that pushed through the eastern half of the TN Valley Saturday evening produced hail, damaging winds and 3 known tornadoes. Here is how the BTI performed and how it was useful in providing our meteorologists with additional information to provide you with the most advanced notification of the potential tornado threat. During the recent severe weather event, the National Weather Service confirmed 3 tornadoes. Here is how the BTI values were related to each of these events and how much advanced warning they helped provide.

Valley Head, AL Tornado

The strongest tornado of this event occurred just west of Valley Head in De Kalb County. The National Weather Service rated the tornado a EF-1 with maximum sustained winds of 105 mph. The path length was 2.6 miles. The estimated time of when the tornado first touched down was 8:16 PM CDT and was located approximately 5 miles to the north-northwest of Ft. Payne.

At 7:54 PM, approximately 22 minutes prior to the initial tornado touchdown, Storm Force 31’s severe weather technology indicated a storm with twisting winds (Shear) likely. The BTI value was 2.9.  

At 8 PM, 16 minutes prior to touchdown, the storm had moved to near Fyffe and Rainsville and was continuing to move to ENE. WAAY’s BTI value for this storm had jumped significantly to 6.7. An increase by 3.8 in just 6 minutes!

At 8:04 PM, the storm’s BTI value was holding nearly steady and was 6.6. The storm was now approaching the area between Rainsville and Ft. Payne.

At 8:21 PM, as the storm neared Valley Head, the BTI value has decreased some to 4.6. This was still significantly higher versus other storms which had values generally in the range between 0 and 2.5

Using BTI alone, the value provided a 16 minute advance notice of this potential tornado.

Huntland, TN Tornado

The second most powerful tornado of this event occurred across Franklin County, TN. The National Weather Service rated a tornado that occurred between Huntland and Maxwell as an EF-1 with maximum sustained winds of 90 mph. The damage path stretched for 1.5 miles. The initial touch down of the tornado occurred at approximately 7:00 PM about 2 miles north-northwest of Huntland, TN.

The storm initially had a BTI of zero until 7:02 PM when the BTI value rose to 2.9.

At 7:06 PM, the storm was just north of Huntland and near Maxwell and the BTI value had risen to its maximum for the storm, 4.2.  

By 7:13 PM, as the storm approached Winchester, the BTI value had decreased to 2.6

Pisgah, AL Tornado

The third and weakest tornado that occurred in this event occurred in Jackson County, AL, just to the northeast of Pisgah. The National Weather Service rated this tornado as an EF-0 with a maximum sustained wind of 85 mph. The damage path was 1.6 miles long.  The tornado touchdown at approximately 8:11 PM CDT. 

The Storm Force 31 severe weather technology began showing a storm with possible dangerous twisting winds moving northeast towards Pisgah at 7:42 PM and the BTI value at that time was 2.0.

Two minutes later this storm showed some minor enhancement and the BTI rose to 2.2.  At 7:48 PM, the storm was southwest of Gibson Crossroads and continuing to track to the northeast toward Pisgah. The BTI value has rose to 2.3. At 7:52 PM, the storm was nearing Macedonia and the BTI had rose to 2.9. At 7:59 PM, as the storm neared Powell Crossroads, the BTI rocketed upward to a value of 6.7! 

 As the storm continued to track to the northeast and approach Pisgah, the BTI values remained above 6.

In conclusion, identifying and detecting minor, relatively weak and short-lived tornadoes is a difficult task. However, the Baron Tornado Index (BTI) helps pin-point the most likely storms that could produce one of these. It proved itself extremely reliable for each of the three tornadoes that occurred and in general provided about 14 minutes of additional advanced notice. Stay tuned to WAAY-31 to keep your family safe this severe weather season!

Dale Bader/Meteorologist, Storm Force 31

Now the CHILL Arrives

The line of strong to severe thunderstorms associated with a strong cold front have passed through the TN Valley. A few of these storms had reports of strong winds and hail. In addtion, one storm across western Franklin County, TN  reported tornado near Huntland. Here are a few viewer pics that have been received already. If you have others and would like to share them you can email them to weather@waaytv.com

Some more viewer pics that arrived a bit later are here:

Sunday will be a very chilly day across the TN Valley. The morning will start out cloudy with even a few isolated showers/sprinkles. Temperatures will be in the upper 30s to lower 40s as you walk out the door to head to church. Therefore, make sure you take a jacket. Unfortunately, it won’t warm much by afternoon, either. The clouds will try to break but temperatures will only rise into the low 50s.

Dale Bader / Meteorologist, Storm Force 31

The Storm Prediction Center has issued a tornado watch for most of the TN Valley until 9 PM. The only counties not included in the watch are Colbert and Franklin in Alabama. An approaching cold front that stretches from near Paducah, KY to the AL/MS line will continue to move eastward this afternoon and evening. This front will interact with a moist atmosphere to trigger some thunderstorms, some of which may become severe with damaging winds, large hail and a few isolated tornadoes. The biggest threat for a  severe weather risk is north of the Valley from middle TN into KY. However, folks here in the TN Valley need to be weather aware for potentially quickly changing weather conditions. As of 3 PM, no storms have developed in the TN Valley. The nearest storms at this time are located across NW TN. The Storm Force 31 team will be here to keep you up-to-date as conditions change. A new webcast is available at waaytv.com, too.

 Dale Bader /Meteorologist, Storm Force 31

Storm Prediction Center has issued a mesoscale outlook for the TN Valley and northward through TN and into KY for the potential need for a tornado watch this afternoon. At this time, there are no radar echoes showing up anywhere across northern MS/AL and southern TN and my thinking is that the main threat for severe weather exists from middle TN northward. I will continue to monitor the situation closely and will keep you up to date as conditions change.

Dale Bader / Meteorologist, Storm Force 31

Midday Update: A thunderstorm has developed across eastern Lauderdale County during the past hour and has been moving to the NE at 35 MPH. As of 11:50 has entered into Giles County, TN and is heading toward Goodspring and Pulaski. This storm is not severe but is producing some heavy rains. Otherwise, the radar remains clear.

Dale Bader /Meteorologist, Storm Force 31

Will we see record heat or a continuation or winter’s chill?  Will it rain or will drought begin again? And what about severe weather?

We know these are questions that you have been asking. For this reason we have prepared the Spring 2009 Outlook.

In order to create a long range seasonal outlook, there are many parameters to review. Some of thee parameters include, tropical water temperatures in the Pacific, which provide information regarding El Nino and La Nina, current world-wide weather trends and comparing them to historical records, and the amount of soil moisture present.

Currently, the water temperatures in the tropical Pacific are indicating that a La Nina is present. “What does that mean,” you may ask? Meteorologists monitor waters off the coast of western South America all the way to the Australia. There is a normal level that current temperatures are compared to. When current water temperatures in this region are below normal, a La Nina is present. When the opposite is true, El Nino is present. Again, we are currently in a La Nina. However, forecast trends are for the La Nina to gradually weaken which would cause the water temperatures to gradually rise to near normal levels this Spring.

Traditionally, for the Southeastern U.S., La Nina during the Spring brings temperatures that are close to normal with occasional warm spells. Regarding precipitation, rainfall is typically a bit below normal with a Spring La Nina. Since La Nina is not expected to continue through all of Spring, we don’t anticipate that it will be completely a normal La Nina Spring season and instead we will see a bit more in the way of rainfall.

In addition to looking at the Pacific water temperatures, we analyze the most recent weather patterns and short and long range forecast models. When all of the information is put together, meteorologists are able to find previous Spring seasons that appear similar and these are called analog years. Similar Spring seasons reviewed for this outlook were: 2001, 1999, 1996, 1991, 1986, 1968, 1965, 1963 and 1951.

Now, there are several sources you can review for a seasonal outlook and a couple of these include the National Weather Service and the Old Farmer’s Almanac. So before we reveal our Spring forecast, lets take a quick look at both of these sources.

First, The National Weather Service’s Spring Outlook not only includes temperature and precipitation but also the risk of flooding. This year, the Flood Outlook is for significant flooding across the Upper Midwest from the Dakotas into MN and also across the northern OH Valley from IL into OH. Locally for the TN Valley, average conditions are expected. National Weather Service is also forecasting near normal temperatures and precipitation for this Spring across northern Alabama and southern middle Tennessee.

What about the good reliable Old Farmer’s Almanac? Its forecast for both the months of April and May are for well above normal temperatures which means monthly temperatures that average 4 or more degrees above normal and above normal precipitation, too.

Alright, you have waited long enough. Here is the Storm Force 31 Spring 209 Outlook:

April

Temperatures will tend to be a bit above normal. Although, the overall monthly values will not be extreme, a few very warm days with highs into the 80s will be likely. Actually, we are expecting 10 days to reach the 80 degree mark or even higher. Even though temperatures are expected to be slightly above normal for the month, an early cool spell is possible and the last day for possible frost will likely occur during the first week of the month, so wait until around the 9^th or so to plant those tender plants.

Additional good news is expected for April.  Normal precipitation is  being forecasted as is severe weather. At this time, we are anticipating 4 days of severe weather for the Valley.

May

Temperatures will again be on the warm side of normal. However, these temperatures are expected to be less than those during  the month of April. In May, we usually see our first 90 degree day. For the 2009 Spring Outlook, our forecast includes that. On the other hand, unlike some years, only a few days of 90 degrees or higher are anticipated. The opposite side of the spectrum is also expected with a few cool days a with temperatures only around 70 degrees for highs and morning lows in the 40s.

Precipitation for the month will be near normal. Just like April, a few days of severe weather is anticipated. Officially, we are predicting 5 days of severe weather across the TN Valley during May.

Dale Bader / Meteorologist, Storm Force 31

Leads to Storms and a Risk for Severe Weather, Wednesday

Relatively quiet weather will occur over the TN Valley through Tuesday. The only big news, weather-wise, will be whether or not clouds or sun win as the majority weather feature. A cold front will slide southeast out of the Plains Tuesday and move into the TN Valley Tuesday night into Wednesday. With this feature will come showers and t-storms, some of which may be severe.

A second risk of severe weather is possible on Friday. As a result, now is a great time to make sure you have your severe weather preparedness plans in tact and if you have not already done so, check out and sign up for Weather Call. You can do so by simply clicking here.

Dale Bader / Meteorologist, Storm Force 31

Minor Earthquake Shakes St. Clair County

A magnitude 2.2 earthquake occurred St. Patrick’s Day at 6:27 PM in St. Clair County, AL.  The epicenter of the earthquake was located 5 miles west of Ragland, AL or about 36 miles ENE of Birmingham, AL. The United States Geologic Service reported the depth of the earthquake to have been 9.8 miles. Some of the nearby towns that may have felt some shaking would have included: Pell City, Tanyard, Wattsville, Lincoln, Sulphur Springs, Ashville, Ottery and Margaret.

Earthquakes, rather rare, are not uncommon for Alabama. Most of them occur with a magnitude that is less than 4 and occur across the northern half of the state. This is the third earthquake in the state of AL during the last 6 months. The others were a magnitude 2.2 earthquake that was located near Centreville, AL on February 18, 2009 and a magnitude 2.3 earthquake that was located near Jacksonville, AL on November 14, 2008.The earthquakes that do occur and affect the state are from one of four seismic zones: New Madrid, Southern Appalachian, South Carolina and the Bahamas Fracture.  The Ragland earthquake was likely a result of the Southern Appalachian Seismic Zone.

If you would like to learn more about earthquakes in Alabama, you can visit the Alabama Geologic Survey’s website or simply click here.

Dale Bader / Meteorologist, Storm Force 31