Updated Tornado Information Coming Soon!

Posted by pmarshwx on 24 Mar 2011 | 0 comments

Greg Carbin, Warning Coordination Meteorologist at the Storm Prediction Center (SPC), informed me today that he has updated the SPC tornado database up through 2010. Thus, in the coming days, I’ll updated the graphics to include the last 2 years worth of tornadoes. I look forward to playing with the updated data!

March Tornadoes

Posted by pmarshwx on 6 Mar 2011 | 1 comment

After a long hiatus from blogging for most of February, I’m back at it as things appear to be slowing down just enough to let me have coherent thoughts again. This is fortunate since we’ve entered a new month and I need to post the March tornado graphics! This post should do the trick!

Above is a choropleth map of tornadoes by county. As we head into spring, warmer temperatures and more moisture begins making its way farther north and west than January and February. This allows for surface-based thunderstorms to develop farther north and west, and consequently we see a considerable expansion north and westward in the number of tornadoes. However, numerous tornadoes have been reported in the central valley of California.

If we break the tornado numbers down by state, we can see that Texas is the big winner (or loser depending on your point of view), with the other southern plains states having high numbers of tornadoes. The southeastern states have little change with the February numbers, making this area one favored area for tornado development.

The actual counts by state are broken down below

What about injuries? Keeping the same state ordering above (namely, in decreasing order of tornadoes), we can see the breakdown of injuries by state. For the third month in a row, Mississippi leads the nation in injuries, with Arkansas not far behind.

Examining the number of fatalities, Mississippi no longer leads the nation. Arkansas has the most number of March tornado fatalities, thanks in part to the 1 March 1997 tornado outbreak.

Lastly, here is a summary figure combining the last three figures.

February Tornadoes

Posted by pmarshwx on 12 Feb 2011 | 1 comment

Since I forgot to post a “Question of the Week” this week due to continued winter weather and because the snow battered center of the United States has begun its long awaited warm-up, I thought I’d go ahead and share the statistics and figures relating to February tornadoes. The plots and statistics are similar to those I computed for January that can be found in posts here and here.

Above is a figure depicting the number of February tornadoes per county for the years 1950 to 2009. Most tornadoes tend to occur in the southeast United States, however tornadoes have been reported as far west as California and Hawaii, and as far north as Oregon and western New York!

If we sum up the number of unique tornadoes from the country data and turn it into the number of tornadoes by state, it would look like this:

Florida and Mississippi lead the way with over 180 tornadoes, followed by Texas and then the rest of the southeastern states. Breaking down each states numbers, the tallies look like this:

Now, the number of injuries per state break down as follows (please note the order of the states listed on the left is in descending order of number of tornadoes per state):

The number of fatalities per state break down as follows (please note the order of the states listed on the left is in descending order of number of tornadoes per state):

And putting everything into a single, cluttered figure, we have this:

AOTW: More on January Tornadoes

Posted by pmarshwx on 21 Jan 2011 | 5 comments

The answers to this week’s “Question of the Week” might surprise some of you. But first, here are the graphs that answer these questions

Here is a chloropleth map of January tornadoes by state:

Here is a bar graph showing January tornado counts by state, ordered from most to least:

Keeping the states in descending order of most January tornadoes to fewest tornadoes, here is a bar graph depicting the number of injures by state:

And, once again, keeping the states in descending order of most January tornadoes to fewest tornadoes, here is a bar graph depicting the number of fatalities by state:

And even though this plot is a bit crowded, here is a bar chart that combines the three previous charts into one:

Could you figure out the answers? Well, if not, here they are:

1. Which state(s) had the most January tornadoes?
   • Florida (151)

2. Which state(s) had the most January tornado injuries?
   • Mississippi (580)

3. Which state(s) had the most January tornado fatalities?
   • Mississippi (42)

4. Which state(s) had the most injuries per tornado?
   • Deleware (7 per tornado)

5. Which state(s) had the most fatalities per tornado?
   • Oklahoma (0.62 per tornado)

And here are the raw numbers,


State, Tornadoes, Injuries, Fatalities, IPT*, FPT**
AL, 89, 294, 19, 3.30, 0.21
AR, 117, 218, 13, 1.86, 0.11
AZ, 6, 0, 0, 0.00, 0.00
CA, 39, 3, 0, 0.07, 0.00
DE, 1, 7, 0, 7.00, 0.00
FL, 151, 259, 5, 1.71, 0.03
GA, 91, 130, 5, 1.42, 0.05
HI, 6, 4, 0, 0.66, 0.00
IA, 13, 11, 1, 0.84, 0.07
IL, 28, 140, 1, 5.00, 0.03
IN, 17, 7, 3, 0.41, 0.17
KS, 3, 0, 0, 0.00, 0.00
KY, 24, 39, 4, 1.62, 0.16
LA, 123, 142, 10, 1.15, 0.08
MD, 3, 0, 0, 0.00, 0.00
MI, 1, 0, 0, 0.00, 0.00
MO, 77, 276, 8, 3.58, 0.10
MS, 127, 580, 42, 4.56, 0.33
NC, 24, 50, 1, 2.08, 0.04
NE, 6, 0, 0, 0.00, 0.00
NV, 1, 0, 0, 0.00, 0.00
OH, 6, 3, 0, 0.50, 0.00
OK, 16, 32, 10, 2.00, 0.62
OR, 1, 0, 0, 0.00, 0.00
PA, 6, 18, 0, 3.00, 0.00
SC, 26, 44, 0, 1.69, 0.00
TN, 48, 210, 14, 4.37, 0.29
TX, 139, 73, 2, 0.52, 0.01
UT, 1, 0, 0, 0.00, 0.00
VA, 13, 14, 1, 1.07, 0.07
WA, 3, 0, 0, 0.00, 0.00
WI, 3, 5, 0, 1.66, 0.00
WV, 2, 0, 0, 0.00, 0.00

*IPT = Injuries Per Tornado
**FPT = Fatalities Per Tornado


QOTW: More on January Tornadoes

Posted by pmarshwx on 17 Jan 2011 | 2 comments

The answer to last week’s “Question of the Week” sparked a lot of posts on Twitter and at least one question posed in the comments. These comments and questions got me thinking about more ways to dissect the tornado database. Thus, I thought for this week’s installment of QOTW, I would continue with the same theme.

Above is the image originally posted in the answer to last week’s question. It depicts the number of January tornadoes each year, broken down by F/EF-Scale rating. Although containing a lot of information, it fails to answer the question I received most often: “How many fatalities have resulted from January tornadoes?” There figure below displays the number of injuries and fatalities by year for 1950-2009. (Note: The y-axis is scaled via a square-root. The thin, smooth line is a smooth trend-line. Thanks to the fine folks on the “ggplot2” listserv for helping me debug an issue with this plot!)

After a small spike from the mid-1960s through the mid-1970s, injuries from January tornadoes decreased slightly and has held relatively steady around 20-25 per year. The exception to this was 1999, which holds the record for most number of January tornadoes, including the largest January tornado outbreak on record. Fatalities appear to follow a similar trend as injuries, albeit with much lower numbers. In total

• January Injuries: 2455 (40.9 per year)
• January Fatalities: 138 (2.3 per year)

We can break down January tornado casualties even more and examine them by F/EF-Scale ratings.

As one might expect, a general increase in casualties is found as F/EF-Scale rating increases. This leads me to this week’s questions.

Above is an image depicting the number of January tornadoes between 1950 and 2009 broken down by county. Using the above image as a guide, between 1950 and 2009:

1. Which state(s) had the most January tornadoes?
2. Which state(s) had the most January tornado injuries?
3. Which state(s) had the most January tornado fatalities?
4. Which state(s) had the most injuries per tornado?
5. Which state(s) had the most fatalities per tornado?

(Hint: A tornado that crosses a county boundary is counted in both counties. Thus, one cannot sum the number of tornadoes per county in a state to find the number of tornadoes per state.)

AOTW: January Tornadoes

Posted by pmarshwx on 15 Jan 2011 | 2 comments

I apologize that this week’s answer is a day late. I was traveling yesterday and unable to access the Internet. But without further adieu, here is this week’s answer.

1. Since 1950, how many (official) tornadoes have occurred in January?
   • There have been 1193 tornadoes during the month of January in the 60 years spanning 1950 to 2009. This equates to an average of 19.88 tornadoes per year in January. Broken down by rating:

     • F/EF-Unknown: 30
     • F/EF-0: 391
     • F/EF-1: 443
     • F/EF-2: 251
     • F/EF-3: 67
     • F/EF-4: 11
     • F/EF-5: 0

As you can see, 1999 was a very active year in terms of January tornadoes. There were several tornado outbreaks that January, including the largest January outbreak on record, which affected parts of Arkansas, Tennessee, Mississippi, and Louisiana.

QOTW: January Tornadoes

Posted by pmarshwx on 10 Jan 2011 | 2 comments

No long post tonight; just the “Question of the Week”.

Since 1950, how many (official) tornadoes have occurred in January? Leave your answers in the comments. I’ll post the answer on Friday.