Terms of Scale: Synoptic and Mesoscale

As you begin to read about meteorological topics, you will come upon a couple of words that may be unfamiliar to you. (More than a couple, actually. Learning the "language" is an important ingredient to grasping any topic). These words have to do with scale, and they are "synoptic" and "mesoscale". Synoptic and mesoscale might be thought of as describing how closely we are looking at something. There are four basic scales by which we might discuss the weather or climate, and synoptic and mesoscale are the two in the middle. Let's look at all 4:

Global scale
If we were looking at earth from space (seeing the planet as a whole) we would be viewing on a Global Scale. Generally speaking, elements thousands of kilometres and greater in dimension are considered global-scale elements. They include the general circulation features, such as the trade winds, prevailing westerlies, Rossby waves and the jet streams, and regions of the atmosphere such as the tropics, the mid-latitudes, the polar regions and the ozone layer.

Synoptic scale
If we move in a little closer (perhaps using a satellite, or map that is viewing a portion of the planet) such as concentrating on the continental U.S., we are viewing things in synoptic scale. The American Meteorological Society glossary gives two definitions of Synoptic:

Synoptic—

1. 1. In general, pertaining to or affording an overall view.
   In meteorology, this term has become somewhat specialized in referring to the use of meteorological data obtained simultaneously over a wide area for the purpose of presenting a comprehensive and nearly instantaneous picture of the state of the atmosphere. Thus, to a meteorologist, “synoptic” takes on the additional connotation of simultaneity.
2. 2. A specific scale of atmospheric motion with a typical range of many hundreds of kilometers, including such phenomena as cyclones and tropical cyclones.

Synoptic scale covers weather elements such as high and low pressure systems, air masses and frontal boundaries, features commonly found on standard weather maps. The size range of elements found on the synoptic scale are usually from tens to thousands of kilometres in breadth, the area of one continent, and may extend from the surface to the lower stratosphere. It might also be referred to as "continental scale".

Mesoscale
The AMS Glossary defines "mesoscale" as:

Mesoscale—

• Pertaining to atmospheric phenomena having horizontal scales ranging from a few to several hundred kilometers, including thunderstorms, squall lines, fronts, precipitation bands in tropical and extratropical cyclones, and topographically generated weather systems such as mountain waves and sea and land breezes.

Mesoscale weather is what you see on the weather maps and forecasts for a specific area, or a state or province. It may also be referred to as "local scale".

Microscale
Looking even closer, we get to the microscale. The microscale includes all atmospheric processes less than two kilometres in size. This size range can include your backyard or garden, your neighbourhood, or a small lake, hills or wooded area. It can even be seen in differences within your garden or around the outside of your house or school. We don't think too much about the microscale, but it is the one in which we most intimately live and the one we have some ability to modify.

As mentioned, the two you will be seeing most frequently are Synoptic and Mesoscale. When you see "synoptic" (in meteorology) think: a feature that would be discernable on a map of the country. When you see "mesoscale" (in meteorology) think: a feature that would be discernable on a map of a couple of counties (or in the range of one radar unit, perhaps).

JetStream: Online School for Weather

For a good overview and introduction of meteorology topics, I recommend JetStream: An Online School for Weather by the National Weather Service. There is one section specifically on the topic of Thunderstorms, but you will find a lot of information in the related topics (such as Synoptic Meteorology.

The Three Main Ingredients for Severe Storms

Our discussion into Severe Storm Forecasting has to start somewhere, so let's begin with the 3 Main Ingredients for thunderstorms. Thunderstorms, by the way, are also referred to in scientific papers as "deep, moist convection" (DMC, for short). So there's our first acronym! DMC = Deep, Moist Convection = thunderstorm.

So what are the three main ingredients? In his published paper (Weather and Forecasting 1995, entitled "Severe and Convective Weather: A Central Region Forecasting Challenge") Richard P. McNulty, a meteorologist in the National Weather Service's Training Center says that those three ingredients are:

Convective instability, moisture, and a source of lift

Put those three ingredients together and you have the makings of a thunderstorm. Whether it becomes a severe thunderstorm depends on the amount (or degree) of those ingredients (and, for example, how long-lived the storm is in such an environment. A severe storm that moves into drier air is not going to remain severe, for instance.

For a good look at these three ingredients (explained briefly with illustrations) see the JetStream page: http://www.srh.weather.gov/srh/jetstream/mesoscale/ingredient.htm We'll look at each of those three main ingredients in more detail as we go along.

A Disclaimer: Severe Storms are not all Fun and Games

This has been said many times, in many places, but it bears repeating here: While storm chasing (stormchasing) has been "romanticized" by movies such as Twister, and (to a lesser extent) on sensationalistic television documentaries (such as on the Discover Channel or National Geographic) it is important to remember that these forces of nature are serious business and result in great losses of life and property each year. Even storms that do not produce tornadoes can threaten life and property through large hail and high winds. Even less-intense storms can cause traffic delays, destroy crops, interrupt electrical power, and cause flash flooding.

This is all the more reason to be knowledgable about Severe Storms Forecasting. Responsible storm chasing (stormchasing) is not about putting oneself in danger. It is not about rejoicing in the loss of life and property that these severe storms sometimes cause (or exploiting it). Responsible storm chasers (stormchasers) feel a personal responsibility to report what they see to local authorities for the early-warning and protection of the population. There have even been times when a storm chaser has been the first person on the scene of destruction and assisted people out of the rubble of their home.

The vast majority of these storms take place in the wide open spaces of the rural Plains states where their impact on people is usually negligable. No sane storm chaser goes out hoping to see people's homes, property or livelihoods damaged or destroyed. It is the dichotomy of severe storms that they are, at once, awe-inspiringly beautiful and fearsome to experience firsthand. A well-informed storm chaser learns to stay out of harms way, and works to help others be safe, as well.

A YouTube Introduction to Storm Chasing: Warren Faidley

If you are completely new to storm chasing, you might appreciate the appeal by viewing this YouTube video of Warren Faidley. Warren has been at this a while and is certainly not the only storm chaser to achieve some degree of "fame" in the field. However, there are probably even more storm chasers who will tell you that "fame" has nothing to do with their motivations for chasing storms. I'll be passing along more storm chaser's sites and notable videos and stills, as we go along.

What "Learning to Forecast Severe Storms" is all about

You've found the very first post of this blog, so let me outline my purpose in creating this weblog.

Like most storm chasers, I started with in awe of the beauty and excitement of severe storms (as a child). I was introduced to the Stormtrack Forum a couple of years ago and have learned a fair amount by reading and asking questions there. There are some great guys in the Storm Chaser Community that remember what it was like to "scale" the learning curve and share their knowledge with others.

Clearly, the most important skill a successful storm chaser must develop, is the ability to be in the right place at the right time. You can't call it a successful chase if there is a severe storm and you are two counties away from the action. So forecasting (including AHEAD of a chase day, ON the chase day, and ON THE FLY while "in the field") are vitally important. Gleaning information from the Forecast threads on the Stormtrack Forum can be very difficult for the Newbie:

First of all, you can't give the same amount of weight to every poster. There are all sorts of experience levels that post and some of them are more knowledgable than others. Some of them take more information into account when making their forecasts. Let's face it: Some of them are just more successful than others.

Secondly, many of them are using "lingo" that may as well be Greek to the newbie. As in any specialty, learning the terms: the jargon, the acronyms, the abbreviations, is the first place to start. StormWiki is a good place to start getting a handle on the terms.

Thirdly, many storm chasers have backgrounds in meteorology or are meteorology students. Some even work for the SPC. They have a handle on forecasting tools that may seem "out of reach" for the layman. However, take heart in the fact that many "laymen" have access to most of the data, and many of the same tools. In fact, while understanding general meteorology is certainly not a liablity, a storm chaser's main interest is going to be on the meteorology of severe storms (particularly in the Spring and Summer months). This can be like a subspecialty. You don't need to learn EVERYTHING about meteorology, just that part of it that applies to Severe Storm Forecasting (and for most storm chasers, the goal is Tornado-Producing Storms: Supercells).

So this blog is going to be a journal of my ignorance, confusion and (hopefully) growing understanding of Severe Storm Forecasting. I'm hopeful that Storm Chasers, meteorologists (pro and amateur), and meteorology students will add their COMMENTS to my posts and help point me in the right direction. If you are on the same path as me, I hope you will learn along with me and share your knowledge (and questions) in the COMMENTS to these posts.

In addition, I'll be sharing links to sites that are useful both in learning and in forming your actual forecasts, as well as links to other storm chaser's web sites. From time-to-time I'll also be including some YouTube links, for inspirational purposes. I don't expect this to be a "quick trip". Even experienced storm chasers will probably tell you that the path to greater knowledge never ends, but hopefully as time goes by the "picture" of Forecasting Severe Storms will become clearer and clearer.