Global Warming, is it causing the warm temperatures we've seen this Winter and Spring?

Hi it's Rebecca again, As I said on my fan page the other day, several people have been asking me if the above average temperatures are a result of global warming?  It's a very good question, many areas across the United States and parts of northern Canada  are seeing temperatures 20 to nearly 40 degrees above average.  A large ridge of high pressure and the northern placement of the jet stream is largely responsible for the warm temperatures seen in this region for the last few weeks. Also, the Winter of 2011-2012 was very warm. The National Climatic Data Center (NCDC) named this  winter ( December, January and February) the fourth-warmest for the lower 48. As a side note the winter of 1999-2000 was the warmest on record). Above-average temperatures were most noteworthy  across the Northern Plains, Midwest, Southeast and Northeast. The NCDC said twenty-seven states had winter temperatures that ranked among their 10 warmest on record. In fact the state of New Mexico was the only state that had winter temperatures below the 20th century average. I want to apologise for the length of the post. But it is a vast and complicated subject. I kept it as brief as I could.

So it's easy to see why the question of global warming comes up. I've been giving answers like, La Nina (ocean currents), the Jet Stream, (upper air patterns), and other reasons  have been the cause of these things. I will touch on these reason is a bit...Anyway, this blog post will take a deeper look on what's been going on, what the heck is global warming anyway, take a look at green house gases, and a few other things as well. The post will deal with the scientific and historical  side of things, it will try to keep away from the  political side as much as possible.  I will present the facts as I see them, and leave the meaning up to you.  

What the heck is global warming?

Global warming is when the Earth heats up (the temperature rises). It happens when the Sun's solar energy is trapped in the Earth's atmosphere. The heat and light cause the planet to warm up, which increases the temperature. Generically speaking, "Global Warming" means that the Earth is getting a little warmer each year. The greenhouse effect is not just found on Earth. It occurs for all planetary atmospheres containing greenhouse gases, and is responsible for them being warmer than would be the case otherwise. The greenhouse effect is a natural byproduct of a living biosphere like the Earth.  If left unchecked, it would lead to something called the runaway greenhouse effect, when the atmosphere gets so hot, that the oceans would boil. Some feel, the runaway greenhouse effect involving carbon dioxide and water vapor may have occurred on our sister planet Venus.

What are green house gasses?

The name comes from the effects you would see in a real greenhouse. The Sun's energy gets trapped inside the greenhouse by the glass. Thereby keeping the environment warm enough for plants to stay alive even in the dead of winter.  The process is the same for the Earth (see fig 1), without a greenhouse effect the planet would not be able to  sustain life as we know it.

                                                                                   Fig 1

  

 Gases that contribute to the greenhouse effect include:

Water vapor. The most abundant greenhouse gas, but importantly, it acts as a feedback to the climate. Water vapor increases as the Earth's atmosphere warms, but so does the possibility of clouds and precipitation, making these some of the most important feedback mechanisms to the greenhouse effect.

Carbon dioxide (CO2). A minor but very important component of the atmosphere, carbon dioxide is released through natural processes such as respiration and volcano eruptions and through human activities such as deforestation, land use changes, and burning fossil fuels. Naturally occurring CO2 has a seasonal cycle.  CO2 is a natural component of Earth’s atmosphere and a key ingredient in photosynthesis. during photosynthesis CO2 is used by the plants during the growing cycle, then the plants release the CO2 as a respiration byproduct throughout most of the year. Both exchanges are more or less equal.  Without carbon dioxide all life on Earth would cease to exist

Methane (CH4). Naturally occurring terrestrial CH4 emissions are dominated by wetlands where anaerobic decay of organic material results in production and release of CH4. Other natural CH4 sources include wild fires in both forests and grasslands, and wild animals and domestic livestock. Humans activities that contribute to atmospheric CH4 include the decomposition of wastes in landfills and  agriculture ( especially rice cultivation).   On a molecule-for-molecule basis, CH4 is a far more active greenhouse gas than carbon dioxide, but also one which is much less abundant in the atmosphere.

Nitrous oxide. Naturally occurring terrestrial N2O emissions are primarily due to microbial action in soils especially in tropical region. However once again human activities contribute to N2O production.  Farming cultivation practices, particularly the use of commercial and organic fertilizers, fossil fuel combustion, nitric acid production, and biomass burning.

Chlorofluorocarbons (CFCs). These greenhouse gases don't occur in nature. CFC's are synthetic compounds used in a number of applications,  primarily in aerosols. They also contribute to destruction of the ozone layer However they are largely regulated in production and release to the atmosphere by international agreement.  

Now that we know what greenhouse gases are; let's look at how much human's effect the balance.  With all the hoopla you might think we  contribute a majority of these gases. However,  here are the statics, humans only  contribute about .28% of the gases that cause the  greenhouse effect. Water vapor makes up about 95% of the greenhouse effect. CO2 and other trace gases round out the greenhouse gases at about 5% for all of them. Of that 5%, only 3% is CO2, and most of that is natural. Again, our contribution to the greenhouse effect is a paltry .28%. I bet that got your attention.

 Looking below you will be able to see what gases make up our atmosphere.  

                                                   Atmospheric Composition

                Permantent gases in the atmosphere by percent are:

    Nitrogen    78.1%

   Oxygen      20.9%

   (Note that these two permanent gases together comprise 99% of the atmosphere)

  Argon        0.9%

   Neon         0.002%

   Helium       0.0005%

   Krypton      0.0001%            

   Hydrogen     0.00005%

 Variable gases in the atmosphere and typical percentage values are:

   Water vapor     0 to 4%

   Carbon Dioxide  0.035%

   Methane         0.0002%

   Ozone           0.000004%

Water vapor varies from 0% over deserts and locations with temperatures below freezing to 4% over oceans.

The percentage of these gases is not constant; they very with attitude.

I should add, everything in the atmosphere, including dust, contribute to the "Green House" effect.


Global Warming and history.

The main argument that is currently popular with global warming supporters is :  The Industrial Revolution and the increasing industrialization since then, coupled with the explosive human population growth, as primary factors that are contributing to increases in the concentration of carbon dioxide in the atmosphere.  and is the reason the Earth's temperatures have risen over the last 100 years  As you can see in the above graphic of the atmospheres composition, humans do contribute greenhouse gases. There is no doubt that it is helping warm things up. However, with such infinitesimally small amounts, it is most likely numerous interrelated links that are causing the average global temperatures and  carbon dioxide to be on the increase.

Looking at the charts below, you can see that there have been plenty of times the Earth's average temperatures have been warmer than they currently are (see fig 2). 

                                                                                        Fig 2

                                                                                         Fig3

          Fig 4

                                                                                          Fig 5

In figure 4 you can see there have been over 40 periods of warming and cooling since 1480 AD. Over 92% of the timeline was  before the industrial era.  Most of the time line from 1480 AD until now was  before CO2 emissions could possibly be a factor during the times of warming.

In fig 3 you can see the two most recent warm-ups (before the current one) were the Medieval and Roman warm periods.    The Roman Warm Period (RWP) has been proposed as a period of unusually warm weather in Europe and the North Atlantic that ran from approximately 250 BC to 400 AD.  Scientists have determined that Between 230 BC and 40 AD there was a period of exceptional warmth in Iceland that was coincident with the RWP in Europe that ran from 200 BC to 400 AD. Most of the time Paleo-climate Modelling is done with such things as tree rings and ice core data. The problem with tree rings is the rings can only tell average annual temperatures. However, a new technique to reconstruct past temperatures has been developed by scientists at the University of Saskatchewan, Canada and Durham University, England, using the shells of bivalve molluscs. The Scientists used oxygen isotopes in the shells to measure the temperatures of the time. William Patterson, lead author of the study This Icelandic shell data series suggests that the RWP had higher temperatures that those recorded in modern times. I won't bore you with the details. But, the paper can be found online here.


I will take a little historical side trip. The Viking Period took place from the ninth century to the middle of the eleventh. it was during this time that the Norwegian Vikings were raiding and exploring vast areas of Europe, and even parts of the Mediterranean sea. The Vikings  were settled between 865 AD – 930 AD in Greenland and Iceland. However, they were forced to abandon the settlements because of the return of extremely cold conditions, The cool period was prolonged. Western settlement in Greenland was abandoned by 1360 AD and by 1450 AD settlements in the east were abandoned as well. This time frame matches well with figure 5.

Figure 5 also shows that the Dark Ages were during another cold period. Around 410 AD the cooler temperatures returned, The era called the Dark Ages, corresponds with the  cold period between 400 AD and 600 AD.

After the Dark Ages Cold Period another warm period emerged, this one was called the Medieval Warm Period. during this warm period Europe had a cultural awakening. The awakening led to one of the greatest ages of invention and discovery ever known, The Renaissance, this period ran from around the 14th to about the 17th centuries.


The Medieval Warm Period was followed by another cooler period which is often referred to as the Little Ice Age. It lasted from about the mid to late 1300s into the late 1800s, almost 500 years. During this cold period, the brutally cold winters of the  American Revolution were fought. In Europe, it led to the rise of Napoleon Bonaparte and his invasion and deadly retreat out of Russia during the brutal winter of 1812, the French Revolution of 1830, and numerous other revolutions across the European Continent. Many feel the Little Ice Age lead to the Industrial Revolution and the beginning of our modern way of life.  


One more little historical side trip, a hundred years ago, following the end of the Little Ice Age Cool Period, RMS Titanic hit an iceberg that was released as the next  global warming period began to be felt.   The sinking of the Titanic caused the deaths of 1,517 people in one of the deadliest peacetime maritime disasters in history.


The Sun and Global Warming.

I don't like speaking in absolutes, But I will give myself exception this one time. We all know, that without the Sun, the Earth would be a chunk of rocky ice in space. The sun is 750 times bigger than all of the planets in our solar system put together. Another thing we all know is the sun is extremely hot. The sun's surface temperature is about 10,000 degrees Fahrenheit. And one more thing we all know,  the Sun is what  warms the Earth, this is easily demonstrated, go outside on a partly cloudy day, when a cloud comes between you and the Sun, you feel the temperature drop a few degrees.  Because of all of this, when the Sun gets hotter, the Earth gets hotter, and visa versa. If you've been following my blog post, most of you know that I'm a big believe in cycles when it comes to weather and climate. The Sun also has cycles.  These cycles go from the more familiar 11 year sunspot cycle to ones that last for millions of years.

The Solar Cycle (Solar Magnetic Activity Cycle). This cycle is what is commonly known as the Sunspot Cycle; it has a  period of about 11 years (see fig 6).  The cycle of solar activity is characterized by the rise and fall in the numbers, surface area, and placement of sunspots. When the sunspot activity is high it's  called the Solar Maximum, while the period of fewer sunspots is called the Solar Minimum. It reverses itself in both hemispheres from one sunspot cycle to the next. Therefore a full cycle takes around 22 years. The Suns magnetic field varies greatly during the cycle, During the solar maximum, the magnetic field is strong, so the Suns surface temperature is higher. On the other hand, during solar minimum, the field is weak, so the surface temperature is lower.  Since the Sun is responsible for how warm the Earth gets; well I think you can see where I going with this.  This whole spiel has been heading for one place, The Maunder Minimum.

The Maunder Minimum was a period  that the Sun went through a period of inactivity. it occurred in the late 17th century roughly  between 1645 to 1715 (see fig 7).  During this time very few sunspots were seen. If you look at fig 5 you will see that is about the time of the Little Ice Age. Many feel the Maunder Minimum played a big part in causing the Little Ice Age. I'm sure the AO and NAO had a part to play as well.  Looking at ice core samples, there is evidence that the Sun has had similar periods of inactivity in the more distant past. Clearly there is a link between the solar cycle and  terrestrial climate. A lot more research need to be done in this area. there is one more cycle I what to briefly touch on, the Milankovitch Cycle.

Milankovitch Cycle, in the early part of the 20th century, Mulitin Milankovitch  developing a mathematical theory of climate based on the seasonal and latitudinal variations of solar radiation received by the Earth. The Milankovitch Cycle is based on three principles: Variations in the Earth's orbital eccentricity, Changes in obliquity, and Precession.

1. Variations in the Earth's orbital eccentricity....this is the shape of the orbit around the sun.
2. Changes in obliquity....changes that the Earth's axis makes, the in the angle of the axis vs. the plane of Earth's orbit.
3. Precession....This is the  change in the direction of the Earth's axis of rotation. Imagine how a top spins, as it slows down the tops axis angle changes to its plain of movement. in other words the top wobbles. Figure 8 shows an illustration of the Milakovitch Cycle.

The Milankovitch Cycle can be directly tied to the timing of the Great Ice Ages.

Could there be other longer term cycles that we know nothing about, because they've never been observed?  Absolutely!


                                                                                      Fig 6
                                                                   

                                                                                      Fig 7

                                                                                      Fig 8

The earth has warmed and cooled in cycles for millions of years. The Sun has a huge impact  on our climate. Russian Academy of Sciences, Dr. Dmitriev has said "our entire solar system has been changing. His research has found that every planet in our solar system, the sun and even our moon are experiencing increases in energy field, changes in luminosity and even changes in atmosphere". Other scientists have verified his findings. The Sun causes a vast majority of the global warming we see; some place it as high as 99%. Billions of years ago, the sun was much cooler than it is now....over time the sun will continue to get hotter. I will now discuss a little about ice cores and what they show about solar cycles, polar ice amounts, and global warming.   



Ice Cores


                                                                                      Fig 9

Figure 9  shows data from two different core drilling sites in the Antarctic. The one in blue (EPICA) is managed by the European Union. The green one (Vostak) is managed by Russia. The red one shows the ice volume at that point in the same period

The graph shows that Earth's  overall temperature swings from 6 degrees Celsius (43 degrees Fahrenheit)  warmer to almost 9 degrees Celsius (48 degrees Fahrenheit) cooler than our current temperature. From this graph, it's easy to see the ice volume is directly proportional to temperature.  The warmer the overall temperature the less ice by volume you have.  As you can see there is a regular pattern. This covers 450,000 years, humans have been producing CO2 for a little more than100 years. The  percentage of our contribution to this graph is  0.022222222222222223%. this shows that  these temperature swings have nothing to do with humans. Besides the Sun there are other factors going on that we don't understand.

Fig 10 show generally the same data.

                                                                                     Fig 10

Besides ice volume being directly proportional to temperature, the graph also shows a cycle that is almost like clockwork. It seems the cooling cycles run for 80,000 years followed by a  warming cycle that last around 20,000 years. It seems you can set your clock by the ice age cycle (fig 10). In fact since we came out of the last Great Ice Age about 20,000 years ago....we look to be due for another great ice age. in the next 1000 -2000 years.

NASA ice core data

NOAA ice core data

Vostok Antarctica ice core data


There is a lot of evidence that we have been cooling off over the past 20 years. Here is temperature data from the Pacific Northwest. it shows that temperatures have cooled off starting in 1992 thru 2012 by -1.0 to -1.5 degrees F. At least for the Pacific Northwest.

Rural:

Hanford (khms):

10 yrs (1992-2001) mean (deg F):  54.4

10 yrs (2002-2011) mean 53.7 -0.7

5 yrs (2007-2011) mean 53.0 -1.4

Farmland:

Corvallis agrimet:

10 yrs (1992-2001) mean (deg F):  52.8

10 yrs (2002-2011) mean 52.3 -0.5

5 yrs (2007-2011) mean 51.7 -1.1

Farmland:

Forest Grove agrimet:

10 yrs (1992-2001) mean (deg F):  52.9

10 yrs (2002-2011) mean 52.4 -0.5

5 yrs (2007-2011) mean 51.8 -1.1

Farmland:

Eugene (keug):

10 yrs (1992-2001) mean (deg F):  52.9

10 yrs (2002-2011) mean 52.5 -0.4

5 yrs (2007-2011) mean 51.9 -1.0

Urban:

Portland (kpdx):

10 yrs (1992-2001) mean (deg F):  54.6

10 yrs (2002-2011) mean 54.4 -0.2

5 yrs (2007-2011) mean 53.7 -0.9

Urban:

Salem (ksle):

10 yrs (1992-2001) mean temperature (deg F):  53.4

10 yrs (2002-2011) mean temperature:  53.2 -0.2

5 yrs (2007-2011) mean temperature:  52.9 -0.5

 The above data can be found at this site.

The facts that I have shown show that the burning of fossil fuels,  is not the cause for our current global warming issues. ( Because of lack of time, I didn't show all the data.). However, the data shows that these warming and cooling cycles are a natural product for our Planet. We humans have only been burning fossil fuels for less than 150 years. The warming and cooling cycle has been going on for millions of years.

One last thing before I conclude, the Intergovernmental Panel on Climate Change (IPCC) is a scientific intergovernmental body first established in 1988 by two United Nations organizations and has since been endorsed by the United Nations General Assembly.  Its mission is to provide comprehensive scientific assessments of current scientific, technical and socio-economic information worldwide about the risk of climate change caused by human activity, its potential environmental and socio-economic consequences, and possible options for adapting to these consequences or mitigating the effects. The IPCC is run by politicians, in 2007 the IPCC published a report on their findings on global warming. The report made the future look grim. However, the report ended up having to be retracted, due to inflated statics, and half truths. One of the falsehoods has about solar forcing. The paper halved the maximum likely influence of solar forcing on warming over the past 250 years from 40% to 20%. This was based on a reanalysis of the likely changes in solar forcing since the 17th century. Most of the time when we hear of global warming dangers, it comes from politicians and not scientist.  I know the scientific community is a little divided on the subject, There are scientists on both side of the isle. I'm not going to make a political statement, But I think we owe it to ourselves to let science find the answers and not politicians. there is more than enough junk science on both sides. we owe it to ourselves, to find the facts. and let science find the answers to this highly complex problem.

links to  papers and articles  on the Suns influence on the Earths temperatures and other global warming issues.

Paper on pattern of stange errors in solar and climate data

Site with many links to lots of global warning information.

So if it's not  global warming, why was the Winter and so far this spring so warm?  As I've been saying on my weather page and this blog  We've had a Jet Stream that has stayed north of the lower 48 for the most part. The Jet has been very fast, this has keep the pattern zonal.  This along with a positive AO and a positive NAO. These oscillations are normal, atypically long, but not  unprecedented. because we had and still have a positive NAO. it's preventing arctic air from making big moves into the US. And as I said in a earlier blog post, the early start for the severe season is because of the warm winter.  

Let me close by saying, as I said, the main argument that is currently popular with global warming supporters is :   industrialization and human activities are the primary factors that are contributing to increases in the concentration of carbon dioxide in the atmosphere. I have presented information; that shows this can't be the case. As I also said, we are adding greenhouse gases to the atmosphere. But, the amount is so small that it makes no difference in the long run .  IMO,  Mankind for all his technological might, is a babe in the woods, when compared to the power of Earth's oceans and ecosystem, Sun, and other immense forces both known and unknown.  Short of a complete nuclear war, the human race simply doesn't have the power or the understanding to change the climate on a global scale.

I've shown you the facts. it's up to you to decide what to make of them.  I hope you enjoyed reading this, maybe even learning a thing or two.



Rebecca  

Why The 2012 Severe Season is Starting So Early.

Hi Rebecca here again, as I've been saying with the ridiculously warm winter, severe weather season is starting very early across the county. Last week had almost 3000 records broken.  The winter of 2011 - 2012 will go down as the 4th warmest on record. According to the NWS 36 states will have a warmer than average spring. The pattern we've been stuck in has severe weather and tornado reports setting a near-record pace. We've already had outbreaks in January, February, and  the exceptionally deadly outbreak on March 2nd and 3rd. The destructive tornadoes in Michigan the other day is the latest example. The tornado that struck Dexter, Michigan had winds of 135 mph; it caused considerable damage that will cost millions to rebuild, fortunately no-one was killed.  The one thing that really stands out with the Michigan tornadoes is many of the counties reported their earliest tornadoes in history. Looking at all the long-range climate forecast models, things look a bit alarming temperature wise. If the models are right, we will have well above average temps for most if not all of the spring of 2012. If this is indeed the case, there could be trouble brewing for many areas across the country, including the Northeast. The sad fact is many of these areas, don't have a lot of experience with large destructive tornado outbreaks.

Why is this happening?

If you've been following my weather page, you know I've been blaming the extremely warm winter, on many of the weather woes we've seen across the country this spring. As I said earlier, the Severe / tornado Season for 2012 is off to near-record setting pace, when compared to average  standards. There are many reasons for what we've seen unfold so far this year.

One of the biggest reasons is the lack of winter that we have had this year across the United States. This  has allowed for well above average temperatures to be in place farther north than normal for mid March. Normally, storms weaken this early in year as they move north, However, because of the jet stream pattern we've been in for the last 3 months this modification is not occurring. The current Jet pattern is pulling the extremely warm and moist Gulf air northward. And as most of us are aware, warm moist air is a major ingredient in thunderstorm formation. The Tennessee and Ohio river valleys, parts of the Southeast, and now Michigan have been in the crosshairs, There are a few other factors in play as well, the Rockies are about the only place in the country that has a decent snowpack. Also the Southwest has had extremely dry conditions. Therefore, there is lots of cold dry air that is available for the southwesterly winds to transport northward. 

Another thing that is effecting things is the weakening  La Nina. During La Nina years we do see higher amounts of tornado outbreaks, I have seen evidence that during a weakening La Nina tornado outbreaks tend to be more to the north and often east of the Mississippi. One reason for this is La Nina drives different weather patterns which produce warmer environments throughout the United States.. John B. Knowles and Roger A. Pielke Sr, wrote a paper that talks about EL Nino's and La Nina's effects on tornadic actively.

Here is a link to that paper.

With the lack of cold air in the eastern two thirds of the  country and all of these atmospheric  dynamics coming together, as far north as they have been. It could be a active year in the northern half of the country. The Northeast normally sees its severe season around May and June. However, As I've said on my weather page, the tornado season seems to be running about 6 weeks ahead of schedule. So for the Northeast, we will just have to wait and see how things play out.

Our next severe outbreak potential is starting tomorrow March, 18th in parts of Texas up into Kansas. The severe threat could be a three or four day ordeal. Now while it doesn't look like the set-up we had going into March 2nd.  It looks like we could have a few days of an elevated risk.

Here are a few images of the weather set up on March 19th  for the southern part of Tornado Alley. Right now, the big threat looks to be strong damaging winds, large hail, and flooding rains. But at least a few tornadoes are going to be added to the mix.

                                                                      The NAM 500mb bulk shear  
                                                                     

                                                                      The NAM Helicity 0-1k

                                                                       The NAM dewpoints for Monday
                                                                              

                                                                      The NAM Helicity 0-3K

NAM Lifted Index values

                                                               The NAM 300mb Jet stream pattern

                                                                        Monday's simulated radar                                                                
                

                                                                   SPC's Convective Outlook

                                                                      SPC's Probabilistic Outlook

As we move more into the severe season, it will be important to keep your eyes on the sky. I'm losing count on how many times I've said you have to be prepared for severe weather. So, if you don't have a NOAA weather radio and a severe weather plan. Please take the time to take care of both of those issues.  Because sooner or later, most likely sooner,  the Northeast will be dealing with severe weather. Let hope it's not as bad as we've seen so far this year.

Thank you for taking the time to read this post; your readership means the world to me.

Rebecca

The March 2nd thru 3rd tornado outbreak

Hi, it's Rebecca again, as most of us are sadly aware parts of the Midwest and Southeast were savaged by a large severe outbreak last week. Even though the total number of tornadoes won't be known for a few days yet,  with over 80 confirmed tornadoes , it's safe to say that the  March 2nd-3rd outbreak will be the largest early season outbreak in history.  The Ohio Valley, Indiana, and northern Kentucky regions were hit the hardest.  However, the tornado outbreak spanned 11 states, with non tornadic  damage in four other states including New York State. As of this writing the death count is at 40, If you include the  Leap Day tornado outbreak (February 28 and 29, 2012) that killed 13 people across the Mid-West in the states of Missouri, Kansas, and Nebraska 53 people have died in these two outbreaks. The tornadoes on March 2nd and 3rd left incredible destruction in their wake; that will cost billions to rebuild.  Even though I had seen the setup and knew it was going to be a bad outbreak, I was in awe of what I was seeing. So far, the worst tornado of the outbreak was the EF4 that struck Henryville and Marysville, where those towns were virtually wiped off the face of the earth.

I've been talking about the outbreak on my Facebook weather page. But I wanted to post a blog entry on it that would go into more detail on the setup and breakdown the outbreak as things were occurring; as well as do a little comparison to the Super Outbreak of 1974.

The Setup:

                                                                                   Fig 1

 

                                                                   Surface map for March 2nd 2012

                                                                                Fig 2

                                       

 

The graphic on the left shows the SPC Convective Outlook for March 2nd, with the Moderate Risk area outlined in red, the Slight Risk area outlined in yellow, the area where general thunderstorm development is expected outlined in green. The image to the right, produced by the NOAA Visualization Lab, shows thunderstorm probability from the NAM 00Z

A strengthening low pressure system was pushing toward Missouri,   by the morning of the March 2nd The low had a cold front this front extended southwest  into Texas. Behind the cold fronts lots of cold air was surging forward.  There was one other front that would play a huge role in the upcoming outbreak.  The system that produced the tornadic outbreak on Feb 29 had stalled in the south, this stalled front became a warm front on the March 1st, as the warm front advanced toward the Ohio Valley. it just added fuel to the fire by reinforcing the unstable air mass.

Based on the parameters the Storm Prediction Center (SPC) was seeing on March 1st; the SPC outlined an area from Southern Ohio and points south to the northern parts of the Gulf States as a moderate risk area for severe weather for the next day (see fig 1and 2 above). This included a 15% tornado risk. It didn't take long for things to start, storms started breaking out over Southwest Missouri at 200am CST, NWS issued a severe thunderstorm warnings for hail and strong damaging winds.  Before 8:00 am CST the low pressure system was deepening over southern Missouri and was heading toward Illinois. The location of the low would be crucial on what would occur later in the day; the movement of the low allowed southerly winds to pull a lot of warm moist air from the Gulf of Mexico (which was warmer than normal, warm and humid air is a key component to severe thunderstorm and tornado formation), out ahead of the trailing cold front. With dewpoints rising into the 60′s to near 70 in some spots and high levels of Convective Available Potential Energy (CAPE) (see note A).  At 8:00 am CAPE values where already at 1500 J/Kg. with MLCape values forecasted to be over 2000 J/kg, with  MLCape values above 3000 J/kg  over parts Kentucky and Tennessee. (Significant tornadoes are most often associated with MLCAPE greater than 1000 J/kg.). Based on how things were developing, the SPC issued a high risk for tornadoes for Southern Indiana, Central Kentucky, and North Central Tennessee (see fig 3).

                                                                                       Fig 3

                                                               Showing the area of high risk on March 2nd 2012

  The reason Central Kentucky to Middle Tennessee would be the area for maximum tornado potential was based on several factors.  For one, there was a 130 knot jet; the fastest upper-level winds will be centered right over this area during the afternoon. When you couple that with almost southerly winds (maybe a bit southwesterly at times), you get not only a high difference between wind speed aloft and at the surface, but also a difference in direction. This is called wind shear and it's crucial to sustaining a thunderstorm and allowing it to become strong enough for tornado development. The southerly winds at the surface will help what's called low-level wind shear, and that's usually a pretty big factor in who gets tornadoes. Also, Temperatures were in the 60's, in fact widespread temperatures of mid to upper 70s were reported from the Gulf Coast to Tennessee and Kentucky. The Nashville International airport had a record high of 81; these temps were 11 to 20 degrees above normal for March 2.

The 12Z soundings showed severe weather indexes on March 2nd  that were mind-blowing. The shear profile was nearly perfect, veering wind from SSW at 15kts at the surface to WSW at 70kts at 500mb. Along with the high CAPE values, LFC (Level of Free Convection) (see note B) and LCL   (Lifted Condensation Level) (see note C) showed a Significant Tornado Additionally, the LI (Lifted Index)  (see note D) was at a -6 for the 12Z sounding. Usually anything below an LI of -2 can potentially produce severe weather with isolated tornadoes. However, a -6 is very impressive and indicates a large amount of instability in the atmosphere. (fig 4) is a sounding that shows this data. I will include a link to a blog post that explains how to read a SKEW-T sounding at the end of this post.

                                                                                          Fig 4

                                                                         SKEW-T sounding for March 2nd 2012

As you can see the setup was near textbook for a major outbreak. Everything was pointing to an especially dangerous situation with strong, violent, and long lived tornadoes. Throw in they would be fast moving, rain wrapped, and many occurring during the night and you had a disaster in the making. I will now show a brief timeline on how the outbreak unfolded.

  A brief timeline:

Friday morning,

As I said earlier, there was a strong low that was rapidly intensifying. A cold front stretched southwest from the low into northern Texas.  The warm and moist air was surging north ahead of the low from the central Gulf Coast into the Tennessee and Ohio Valleys.  The upper atmosphere featured huge instability. By 9:10 am, the first tornado of the day developed near Madison and Limestone counties in north Alabama. This tornado was later rated an EF3; with a path length of 34.4 miles and a width of 250 yards. This tornado had peak winds of 140 mph and caused considerable damage in many areas. During the rest of the morning several more tornadoes, many of them long track, were tearing up the landscape.

As the warm front pushed north, The SPC issued several  tornado warnings. However, the major threat was the strengthening low to the west. With the deepening low with the cold front dragging in the cold air, and the northward moving warm front increasing the instability out ahead of the low. It was easy to see that the clash of warm and cold air masses would produce violent, long-track tornadoes over Indiana, Kentucky, Ohio, and Tennessee.

By the early afternoon,

The low-pressure system was stronger and centered over east-central Illinois with a cold front extending south from the low across southeast Missouri to central Arkansas and east Texas. At 12:37 PM CST a tornado was on the ground in Posey County, Indiana. By this time Many Tornadoes were on the ground in several states. One of the hardest hit areas on March 2, 2012 was Henryville, Indiana. In the early afternoon a series of supercells developed in southeast Indiana. This line was moving northwest at speeds of over 60 mph. the first supercell in the line produced the first tornado at 2:50 pm CST. This tornado soon became the strongest tornado of the day. The EF4 hit the small towns of Henryville, Marysville, Chelsea, along with several others.  The tornado smashed into Henryville and Marysville with devastating force, that the tornado all but wiped the towns off the map.  The Henryville tornado had max winds of 175 mph, path length of 49 miles, it obtained a width of one-third to one-half mile.  Below is a fig 5 that shows the track the tornado took. At its peek the tornado had max winds of 175 mph. In fig 5 you can see the track this tornado took. Fig 6 will show the path the EF4 took though Henryville.

                                                                                                Fig 5

Image of the track the southern Indiana EF4 took. As you can see it just missed the compact city of Louisville Kentucky. If it had been just a bit more to the south the amount of destruction and number of deaths would have been almost incalculable.

                                                                                               Fig 6

                                           Picture shows the path the tornado took through Henryville.


Early evening,

The radar showed  Dozens of severe thunderstorms along the cold front and individual thunderstorms ahead of the main line. There were severe tornadoes with this line. At approximately 5:51 PM EST a tornado was spotted on the ground; by 5:58 pm the tornado was moving into the center of West Liberty. In a few minutes frantic calls started pouring out of the town.  The reports  said significant damage was occurring in the downtown area of West Liberty, along with law enforcement reporting that people were trapped in buildings. This tornado was later rated as an EF3.

Dr. Jeff Masters at Wunderground.com reported the West Liberty tornado “The tornado carved a 60-mile-long path through Eastern Kentucky, causing extreme damage in West Liberty. The tornado killed six in West Liberty and two near Frenchburg. At least 75 people were injured. It was the first EF-3 tornado in Eastern Kentucky since 1988.”

After Dr. Masters made this quote, the track of the West Liberty tornado was found to be 95 miles long (see fig 14)

                                                                                Fig 7

                                                       Radar Velocity scan of the West Liberty EF3


The March 2-3 2012 outbreak looks to be the  largest 2-day tornado outbreak for so early in the year. As of March 6th  SPC has 121 tornado preliminary reports. The SPC also has preliminary reports that show 11 tornadoes reported in Georgia and Florida, it also looks like 3 tornadoes occurred on March the 1st. Normally you can weed about 15% of the preliminary reports out.Also,  there still could be a few more tornadoes discovered, Which would bring the total number of tornadoes for the March 2-3, 2012 outbreak in the range of 100-110. To give you and idea of just how sufficient that number of tornadoes is for this early in the season.  The 10-year average U.S. tornado count for the entire month of March is only 87 tornadoes! The record for any entire month of March is 180 tornadoes set in 1976.

A comparison to other Outbreaks:

NWS forecasters could tell something bad was brewing over the central United States. On April 2, 1974, A huge low pressure system with a lot of cold dry are was dropping out of Canada.  On the other side of the coin, there was a huge surge of warm moist air being pushed northward, toward the Mississippi, Tennessee,  and Ohio River Valleys. This huge clash of air masses was going to collide under a fast moving  jet  moving at 122 knots. during the overnight on April 3rd upper level winds had greatly increased over  Alabama, Louisiana and Mississippi as the low pressure system continued to deepen. On the morning of April 3rd, an area of low pressure was located in central Kansas. A warm front extended east-northeastward through the lower Ohio River Valley. South of this front, extremely unstable air had gathered during the overnight hours and was rapidly spreading north. CAPE by 7:00 am was already over 1000J/kg and dewpoint were rising quickly. In the early afternoon of the 3rd all hell broke loose. When the outbreak was over, the storm system had spun-up 148 tornadoes across 13 states, when the damage was surveyed it was discovered that 30 tornadoes were F4 and 6 were F5. The super outbreak of 1974 caused unbelievable destruction and killed 315 people.

 If I changed the date on these parameters; they could easily be substituted for the morning of March 2nd 2012. In fact if you look at the surface charts (Figures 8 and 9) you can see the charts look virtually identical. The two outbreaks had several similarities, both had fast upper level winds, cold air moving east that would slam into the advancing warm moist air out of the Gulf, at just the right time to produce explosive supercells. Also both of the outbreaks had snow on the backside.


                                                                                   Fig 8

     Surface map at 8 am on April 3rd 1974

                                                                                    Fig 9

                                                       Surface map at 7 am on March 2nd 2012

Fig 10

                                       Showing the tracks of the tornadoes in the 1974 Super Outbreak


                                                                                             Fig 11

                                                                                              Fig 12

                                                                                                Fig 13

                                                                                            Fig 14

                                                    Shows the 95 mile track of the West Liberty tornado


Figure 10 shows the tracks of the 148 tornadoes on April 3rd 1974. Figure 13 compares the NWS warnings for the April, 2011 and March, 2012 outbreaks.  If you compare fig 10 to figures 11 and 12 you will see that April 3rd, 1974, April 28, 2011, and March 2nd, 2012, all had huge numbers of tornadoes. With tracks that could almost go on top of each other. All three outbreaks had a fast upper level jet moving at 100-130 knots. with strong low pressure systems and other severe parameters, that could have almost been mirror images of each other.


Notes:

Note A: CAPE stands for Convective Available Potential Energy, it's a measure of the buoyancy of a layer of the atmosphere. The larger the CAPE the Greater the potential speed of the updraft.  Generally the larger the CAPE the taller and stronger the Thunderstorm.



CAPE Values:

0001-10000 J/Kg Marginally Unstable

1000- 2500 J/Kg Moderately Unstable

2500-3500 J/Kg Very Unstable

3500 J/Kg and higher Extremely Unstable.


Note B: The level at which a parcel of air lifted dry and adiabatically until saturated, and lifted adiabatically thereafter, would first become warmer than its surroundings in a conditionally unstable atmosphere.


Note C: Lifting condensation level(LCL) can be said to be the level to which an unsaturated air parcel can be lifted adiabatically before it becomes saturated. Remember, this unsaturated air parcel is moist.


Note D: Lifted Index (LI) is another way to measure atmospheric instability. Negative values indicate instability. the more negative the number, the more unstable the atmosphere is.


Additional links for more information.
   

A blog post on how to read a SKEW-T sounding

A blog post that goes into how a tornado forms.

Link to a website that has several videos of the March 2nd-3rd outbreak

Dr Jeff Masters blog.

Interactive map of damage reports for the March outbreak


Well that's it for this blog installment. I hope you found it informative and interesting. As always, I welcome feedback and questions....until next time.




Rebecca