Frequently Asked Questions
Loaded Gun Chasing
website of storm chaser Mikey Gribble
website of storm chaser Mikey Gribble
Q: What is "loaded gun" supposed to mean?
The term "loaded gun" comes from a loaded gun sounding. First of all, a sounding is a graph that
plots the temperature and dewpoint profile with height. Meteorologists launch weather balloons
that feed back information on how the temperature and dewpoint are changing as the weather
balloon rises through the troposphere and a sounding is the end result.
A loaded gun sounding is a slang term for a sounding that is typical on tornado outbreak days in
the plains. With a loaded gun sounding there is extreme instability ready to be released, but it is
being suppressed by a cap. A cap is a temperature inversion in the atmosphere that works like a
lid on boiling water. It allows instability to build and build until finally it breaks the cap. When this
happens explosive storms are usually the result and with the right conditions in place tornadic
supercells will form.
plots the temperature and dewpoint profile with height. Meteorologists launch weather balloons
that feed back information on how the temperature and dewpoint are changing as the weather
balloon rises through the troposphere and a sounding is the end result.
A loaded gun sounding is a slang term for a sounding that is typical on tornado outbreak days in
the plains. With a loaded gun sounding there is extreme instability ready to be released, but it is
being suppressed by a cap. A cap is a temperature inversion in the atmosphere that works like a
lid on boiling water. It allows instability to build and build until finally it breaks the cap. When this
happens explosive storms are usually the result and with the right conditions in place tornadic
supercells will form.
Q: Is storm chasing like the movie Twister?
I have had a lot of people ask me if chasing is anything like the movie Twister and the answer is
no. 98% of chasing is forecasting, driving, and seeing a whole lot of nothing.
Forecasting is probably the most time consuming aspect of chasing. Forecasting mostly consists
of model analysis and interpretation and looking over current observations(satellite, soundings,
surface charts, etc.). If you don't know what I mean by "model", they are computer models that
simulate the atmosphere. Basically these computers take initial atmospheric conditions, run
thousands of equations, and produce atmospheric conditions for later dates. There are several
different models, but for forecasting severe weather in the plains I primarily rely on the NAM, GFS,
and RUC. I'll use other models too though, just not as much.
For a typical spring tornado outbreak, the forecasting process will start about a week out.
Synoptic scale (large scale) forecasting is the primary focus at this point. What kind of airmass is
over the Gulf of Mexico, is the moisture fetch going to be adequate, what kind of tilt does the
trough have, are the wind fields such that you will have good directional shear, etc. As the chase
day approaches and you get two or three days out you begin to focus in on mesoscale (smaller
scale) details and start to consider targets for your chase. What will be the focusing boundaries
for convection (warm front, cold front, dryline), where are these boundaries going to be located
when convection is anticipated, what convective mode is favored at each area of anticipated
convection, and so on until you narrow down the range of possible targets. Then on the last
twenty four hours leading up to an event you focus in on mesoscale features that could locally
enhance the tornado potential, such as outflow boundaries, mesolows, anomalies in the wind
fields, and countless other slight differences between different locations. Some time in the last
day you pick a target. Basically you work on your forecast daily and zoom in closer and closer on
a target area as the chase day approaches. Of course there are exceptions and this isn't always
the way it works. Some times you know where you want to chase three days out. The triple point
may be the obvious target if the cap is going to be an issue. A warm front or surface low may be
the obvious target if it is the only location with sufficient low-level shear for tornadoes due to
backed surface winds. There are a million different scenarios and every chase is unique.
There is an art to targeting, especially in the earlier part of the season. The jet stream is stronger
during the winter than it is in the summer. As a result, the earlier months of storm season have
stronger wind fields and storm motions are much faster as a result (storms pretty much move at
the mean wind speed throughout the layer they are located in). Forecasted storm motions are a
huge part of picking a target early in the season. When storm motions are going to be >40kts,
you need to setup down stream of where storms are going to fire. When there is going to be fast
storm motions I like to setup about 30-40 miles ahead of where I expect a storm to form. That
way the storm has a chance to mature before it gets to me and is hopefully going tornadic about
the time I get on it. Storms typically take at least an hour to mature and they don't start to put
down tornadoes until they have matured. There are exceptions. The fastest I have ever seen a
storm tornado was the Hallam, Nebraska storm in 2004. It produced the largest tornado ever
recorded (a 2.5 mile wide F4). That storm tornadoed about 30 minutes after it showed up on
radar. That is fast. Anyways, the reason for setting up ahead of where storms will form on fast
storm motion days is because when a storm moves that fast you can't keep up with it for long. If
you get on a storm right after if forms (like you would with slower storm motions) the storm will
outrun you and you will loose it before it goes tornadic. Lots of chasers make this mistake. I
know I have several times. A storm may only be moving at 40kts, but that is as the crow flies,
which means you need to maintain an average speed of 60kts if you are driving on square mile
grid roads, which is usually the case in the plains. It is very stressful and difficult to keep up with
fast moving storms and you need to pick a target that is going to allow you to maximize your
residence time on the storm during the most optimal time for tornadogenesis.
Next comes the driving. I like to get to my target at least two or three hours before I expect
storms to fire, but this doesn't always happen. I am late a lot more often than I care to admit. I
like to be at my target early so that I can do last minute forecasting, which usually takes at least
an hour, then fine tune my target and move if necessary. You need that extra time to allow for
flexibility in targeting. It is nothing to move a hundred miles one way or another after you reach
your original target. Storm chasers drive extreme distances to see tornadoes. Most chases for
me average over 600 miles.
Finally comes the storm. In twister they pretty much skip everything up to this point. In the
movie they watch radar and then haul ass after a storm when a hook echo forms. It doesn't work
that way in real life. You have to be there before it happens. That is why forecasting is so critical
to being a good chaser. If you chase warnings you are going to be too late the vast majority of
the time.
Once I'm on a storm I like to position myself straight East of the updraft base, which is where
tornadoes form. Typically the storm is moving NE or E. This gives me the ability to put myself in
front of the tornado when it is forming so that I can get good up close video of the tornado as it
approaches me. I typically stay about a mile ahead of where a tornado would form and move in
closer when I start to see rapid vertical motion and rotation, which usually proceeds a tornado.
Very rarely do chasers get as close to tornadoes as they do in Twister. I like to get closer than
most, but I still have my limits. I will not put myself directly in front of a violent tornado (EF 4-5).
If you do put yourself directly in the path of a major tornado like that then you are in very
serious trouble if your car gets stuck or breaks down. Roads are usually muddy because the
precipitation part of the storm has already passed through and that needs to be considered. You
can outrun a tornado, but not if the roads are in bad shape. The closest I like to get to stronger
tornadoes is about a quarter to a half mile away. In twister they get closer than that and they do
it on a regular basis. I don't think you would last long if you chased that way.
And finally, with all the forecasting, driving, and busts (days where you don't get a tornado) there
is a whole lot more boring times than exciting ones. You don't see nearly as many tornadoes as
they show in the movie. I like to think that I am a fairly good chaser and over the course of a
season (April, May, and June) I consider myself lucky if I see twenty plus tornadoes. I probably
go on about 20-30 chases each year and drive about 20,000 miles. Early in the year, March and
April, I will typically see a tornado on about 20-25% of the chases I go on. In the peak of the
season I get a tornado about 50-75% of the time. And then towards the end of the season the
percentage drops back down to 20-25%. Personally I think it is pretty damn good if you are
hitting about 50% of the time during peak season. Tornadoes are extremely rare and difficult to
predict. You have to earn them. I didn't get a tornado in my first two years of chasing and that
mostly had to do with me not knowing how to forecast. There is a huge learning curve with
chasing if you are doing it on your own. It is a lot of fun, but you have to work hard at it to be
successful on a regular basis.
no. 98% of chasing is forecasting, driving, and seeing a whole lot of nothing.
Forecasting is probably the most time consuming aspect of chasing. Forecasting mostly consists
of model analysis and interpretation and looking over current observations(satellite, soundings,
surface charts, etc.). If you don't know what I mean by "model", they are computer models that
simulate the atmosphere. Basically these computers take initial atmospheric conditions, run
thousands of equations, and produce atmospheric conditions for later dates. There are several
different models, but for forecasting severe weather in the plains I primarily rely on the NAM, GFS,
and RUC. I'll use other models too though, just not as much.
For a typical spring tornado outbreak, the forecasting process will start about a week out.
Synoptic scale (large scale) forecasting is the primary focus at this point. What kind of airmass is
over the Gulf of Mexico, is the moisture fetch going to be adequate, what kind of tilt does the
trough have, are the wind fields such that you will have good directional shear, etc. As the chase
day approaches and you get two or three days out you begin to focus in on mesoscale (smaller
scale) details and start to consider targets for your chase. What will be the focusing boundaries
for convection (warm front, cold front, dryline), where are these boundaries going to be located
when convection is anticipated, what convective mode is favored at each area of anticipated
convection, and so on until you narrow down the range of possible targets. Then on the last
twenty four hours leading up to an event you focus in on mesoscale features that could locally
enhance the tornado potential, such as outflow boundaries, mesolows, anomalies in the wind
fields, and countless other slight differences between different locations. Some time in the last
day you pick a target. Basically you work on your forecast daily and zoom in closer and closer on
a target area as the chase day approaches. Of course there are exceptions and this isn't always
the way it works. Some times you know where you want to chase three days out. The triple point
may be the obvious target if the cap is going to be an issue. A warm front or surface low may be
the obvious target if it is the only location with sufficient low-level shear for tornadoes due to
backed surface winds. There are a million different scenarios and every chase is unique.
There is an art to targeting, especially in the earlier part of the season. The jet stream is stronger
during the winter than it is in the summer. As a result, the earlier months of storm season have
stronger wind fields and storm motions are much faster as a result (storms pretty much move at
the mean wind speed throughout the layer they are located in). Forecasted storm motions are a
huge part of picking a target early in the season. When storm motions are going to be >40kts,
you need to setup down stream of where storms are going to fire. When there is going to be fast
storm motions I like to setup about 30-40 miles ahead of where I expect a storm to form. That
way the storm has a chance to mature before it gets to me and is hopefully going tornadic about
the time I get on it. Storms typically take at least an hour to mature and they don't start to put
down tornadoes until they have matured. There are exceptions. The fastest I have ever seen a
storm tornado was the Hallam, Nebraska storm in 2004. It produced the largest tornado ever
recorded (a 2.5 mile wide F4). That storm tornadoed about 30 minutes after it showed up on
radar. That is fast. Anyways, the reason for setting up ahead of where storms will form on fast
storm motion days is because when a storm moves that fast you can't keep up with it for long. If
you get on a storm right after if forms (like you would with slower storm motions) the storm will
outrun you and you will loose it before it goes tornadic. Lots of chasers make this mistake. I
know I have several times. A storm may only be moving at 40kts, but that is as the crow flies,
which means you need to maintain an average speed of 60kts if you are driving on square mile
grid roads, which is usually the case in the plains. It is very stressful and difficult to keep up with
fast moving storms and you need to pick a target that is going to allow you to maximize your
residence time on the storm during the most optimal time for tornadogenesis.
Next comes the driving. I like to get to my target at least two or three hours before I expect
storms to fire, but this doesn't always happen. I am late a lot more often than I care to admit. I
like to be at my target early so that I can do last minute forecasting, which usually takes at least
an hour, then fine tune my target and move if necessary. You need that extra time to allow for
flexibility in targeting. It is nothing to move a hundred miles one way or another after you reach
your original target. Storm chasers drive extreme distances to see tornadoes. Most chases for
me average over 600 miles.
Finally comes the storm. In twister they pretty much skip everything up to this point. In the
movie they watch radar and then haul ass after a storm when a hook echo forms. It doesn't work
that way in real life. You have to be there before it happens. That is why forecasting is so critical
to being a good chaser. If you chase warnings you are going to be too late the vast majority of
the time.
Once I'm on a storm I like to position myself straight East of the updraft base, which is where
tornadoes form. Typically the storm is moving NE or E. This gives me the ability to put myself in
front of the tornado when it is forming so that I can get good up close video of the tornado as it
approaches me. I typically stay about a mile ahead of where a tornado would form and move in
closer when I start to see rapid vertical motion and rotation, which usually proceeds a tornado.
Very rarely do chasers get as close to tornadoes as they do in Twister. I like to get closer than
most, but I still have my limits. I will not put myself directly in front of a violent tornado (EF 4-5).
If you do put yourself directly in the path of a major tornado like that then you are in very
serious trouble if your car gets stuck or breaks down. Roads are usually muddy because the
precipitation part of the storm has already passed through and that needs to be considered. You
can outrun a tornado, but not if the roads are in bad shape. The closest I like to get to stronger
tornadoes is about a quarter to a half mile away. In twister they get closer than that and they do
it on a regular basis. I don't think you would last long if you chased that way.
And finally, with all the forecasting, driving, and busts (days where you don't get a tornado) there
is a whole lot more boring times than exciting ones. You don't see nearly as many tornadoes as
they show in the movie. I like to think that I am a fairly good chaser and over the course of a
season (April, May, and June) I consider myself lucky if I see twenty plus tornadoes. I probably
go on about 20-30 chases each year and drive about 20,000 miles. Early in the year, March and
April, I will typically see a tornado on about 20-25% of the chases I go on. In the peak of the
season I get a tornado about 50-75% of the time. And then towards the end of the season the
percentage drops back down to 20-25%. Personally I think it is pretty damn good if you are
hitting about 50% of the time during peak season. Tornadoes are extremely rare and difficult to
predict. You have to earn them. I didn't get a tornado in my first two years of chasing and that
mostly had to do with me not knowing how to forecast. There is a huge learning curve with
chasing if you are doing it on your own. It is a lot of fun, but you have to work hard at it to be
successful on a regular basis.
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