Dan’s Wild Wild Weather Journal

You probably do not recognize the name Ed Lorenz. If I tell you that he was a Mathematician and Meteorologist you probably still would not know who I am talking about. He was famous in science circles though, and you have heard of him too.

You know him for what he discovered.

Back in the early 1960’s Lorenz was running a computer model and made a mistake while inputting the initial data. The mistake was very very small. He misplaced a number after a decimal point.

Kind of like adding your grocery bill up and instead of 49.25cents it was 49.25. and 1/100th of cent. No big deal right. Tell the grocer to keep the change.

Well Lorenz found that when he looked at his computer model, the answer he was expecting was very, very different. He found that in some systems- like the Atmosphere, a very small change in the initial state can lead to a vastly different outcome.

He wrote a paper about it in 1972 called “Can The Flap of a Butterflies Wings in Brazil, Set off a Tornado in Texas”.
Now I bet YOU HAVE heard of that before.

It has come to be called CHAOS theory, and more than one person has said that it was one of the most important discoveries in Physics in the 20th century. One writer at MIT where he was a professor says it ranks right beside Relativity and Quantum mechanics.

Ed Lorenz died last month at the ripe age of 90.

Weather is a chaotic system. This means that a small change in the initial state can lead to dramatically different results in the future.

This is bad news for weather forecasters like me, it means that since we do not know the precise state of the atmosphere everywhere, we will never be able to make perfectly accurate forecasts. A little job security for me I guess!!

Later,
Dan

I have received two really neat pictures illustrating atmospheric phenomena this week. One is local from Ralph Koepsel of Ider. The other was taken from an aircraft carrier in the Pacific.

The first shot was taken Tuesday afternoon and is a great image of Snow Virga falling from high based clouds over Dekalb County. The snow evaporated long before it reached the ground, but it was clearly visible from below.

The other shot one an award as the science shot of the year. A jet, breaking the sound barrier just above the Pacific ocean. The shock waves produced as the plane flew at supersonic speeds caused the air around it to expand and contract. When it expands, the air suddenly cools, and moisture condenses to form a cloud! The picture was taken by John Gay from the top of an aircraft carrier.

Enjoy!

Virga

Here is a press release from NOAA that you may find interesting. Yet another year of unusually warm weather in the USA and worldwide.

NOAA: 2007 a Top Ten Warm Year for U.S. and Globe

The year 2007 is on pace to become one of the 10 warmest years for the contiguous U.S., since national records began in 1895, according to preliminary data from NOAA’s National Climatic Data Center in Asheville, N.C. The year was marked by exceptional drought in the U.S. Southeast and the West, which helped fuel another extremely active wildfire season. The year also brought outbreaks of cold air, and killer heat waves and floods. Meanwhile, the global surface temperature for 2007 is expected to be fifth warmest since records began in 1880. Preliminary data will be updated in early January to reflect the final three weeks of December and is not considered final until a full analysis is complete next spring.

U.S. Temperatures

The preliminary annual average temperature for 2007 across the contiguous United States will likely be near 54.3 degrees F- 1.5 degrees F (0.8 degrees C) above the twentieth century average of 52.8 degrees F. This currently establishes 2007 as the eighth warmest on record. Only February and April were cooler-than-average, while March and August were second warmest in the 113-year record.

The warmer-than-average conditions in 2007 influenced residential energy demand in opposing ways, as measured by the nation’s Residential Energy Demand Temperature Index. Using this index, NOAA scientists determined that the U.S. residential energy demand was about three percent less during the winter and eight percent higher during the summer than what would have occurred under average climate conditions.

Exceptional warmth in late March was followed by a record cold outbreak from the central Plains to the Southeast in early April. The combination of premature growth from the March warmth and the record-breaking freeze behind it caused more than an estimated $1 billion in losses to crops (agricultural and horticultural).

A severe heat wave affected large parts of the central and southeastern U.S. in August, setting more than 2,500 new daily record highs.

Global Temperatures

The global annual temperature − for combined land and ocean surfaces – for 2007 is expected to be near 58.0 F – and would be the fifth warmest since records began in 1880. Some of the largest and most widespread warm anomalies occurred from eastern Europe to central Asia.

Including 2007, seven of the eight warmest years on record have occurred since 2001 and the 10 warmest years have all occurred since 1997. The global average surface temperature has risen between 0.6 degrees C and 0.7 degrees C since the start of the twentieth century, and the rate of increase since 1976 has been approximately three times faster than the century-scale trend.

The greatest warming has taken place in high latitude regions of the Northern Hemisphere. Anomalous warmth in 2007 contributed to the lowest Arctic sea ice extent since satellite records began in 1979, surpassing the previous record low set in 2005 by a remarkable 23 percent. According to the National Snow and Ice Data Center, this is part of a continuing trend in end-of-summer Arctic sea ice extent reductions of about 10 percent per decade since 1979.

U.S. Precipitation and Drought Highlights

Severe to exceptional drought affected the Southeast and western U.S. More than three-quarters of the Southeast was in drought from mid-summer into December. Increased evaporation from usually warm temperatures, combined with a lack of precipitation, worsened drought conditions. Drought conditions also affected large parts of the Upper Midwest and areas of the Northeast.

Water conservation measures and drought disasters, or states of emergency, were declared by governors in at least five southeastern states, along with California, Oregon, Maryland, Connecticut, and Delaware at some point during the year.

A series of storms brought flooding, millions of dollars in damages and loss of life from Texas to Kansas and Missouri in June and July. Making matters worse were the remnants of Tropical Storm Erin, which produced heavy rainfall in the same region in August.

Drought and unusual warmth contributed to another extremely active wildfire season. Approximately nine million acres burned through early December, most of it in the contiguous U.S., according to preliminary estimates by the National Interagency Fire Center.

There were 15 named storms in the Atlantic Basin (Atlantic Ocean, Caribbean Sea and Gulf of Mexico) in 2007, four more than the long-term average. Six storms developed into hurricanes, including Hurricanes Dean and Felix, two category 5 storms that struck Mexico’s Yucatan Peninsula and Nicaragua, respectively (the first two recorded category 5 landfalls in the Atlantic Basin in the same year). No major hurricanes made landfall in the U.S., but three tropical depressions, one tropical storm and one Category 1 Hurricane made landfall along the Southeast and Gulf coasts.

La Niña conditions developed during the latter half of 2007, and by the end of November, sea surface temperatures near the equator of the eastern Pacific were more than 3.6 degrees F (2 degrees C) below average. This La Niña event is likely to continue into early 2008, according to NOAA’s Climate Prediction Center.

Links to data, graphics and analysis, in addition to further national and global data are available online at: http://www.ncdc.noaa.gov/oa/climate/research/2007/ann/ann07.html

NOAA is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and information service delivery for transportation, and by providing environmental stewardship of our nation’s coastal and marine resources. Through the emerging Global Earth Observation System of Systems (GEOSS), NOAA is working with its federal partners, more than 70 countries and the European Commission to develop a global monitoring network that is as integrated as the planet it observes, predicts and protects.

On the Web:

NOAA: http://www.noaa.gov

NOAA’s Satellite and Information Service: http://www.nesdis.noaa.gov

NOAA’s National Climatic Data Center: http://www.ncdc.noaa.gov

Well, we finally broke the heat wave. Many areas had some heavy rains over the last 48 hours as well, so that should make the farmers happy.

I have a tree in the yard that’s about 3 years old. It was almost dead from lack of water. After a good heavy rain Thursday night, it had perked back up nicely! I had been kicking myself for not noticing it, but the rains came just in time!

The damage may be done for many of the farmers in these parts. Several counties in the area are now classified as in severe drought now.

It might seem easy to classify a drought - just look at rainfall and perhaps temperatures, right?

It’s not that simple though.

Do you classify drought conditions based on rainfall for the past 30 days, or 60. What abut 90-180 days? Even rainfall over 6 months ago can impact crops. Some crops need more rain than others and some crops can handle a dry spell better than others.

You see it’s not really that easy!

There are several different drought classification methods in place. Each with their attributes and deficiencies.

One of the older ones is the Palmer Index. There are actually several different versions of it, but the main index is a long term index. The Palmer index will not change much for our area, in spite of getting 1-2 inches of rain late last week.

Below is the Palmer Index for July 2006:

There is a newer more experimental index that has been developed by the USDA and NOAA. This index reacts a bit more quickly to drought busting rains.

The link at the bottom of the image will take you the drought monitor web site where you can read more about how the chart is made.

One final note. The temperature is vitally important in a drought. In the winter, the air and ground are cold, and there is little evaporation from the soil. Just the opposite in the warm season. Evaporation rates are very high and plants are green. The high rate of photosynthesis and transpiration also uses up the soil water quickly.

This means that an inch of rain in January, will keep the soil wet much longer than even 2-3 inches of rain in early August.

It looks like we will go back to a fairly dry pattern next week (But not as hot!). The warm weather, and green plants will suck that moisture out of the ground quickly, and the soil will be bone dry again in just a few days!

Meteorologists like to break the atmosphere down into scales. We have the microscale and the meso scale and synoptic scales and global or planetary scales. Most forecasters concern themselves with the synoptic scale.

If you have a house that is 10 km long it is a mesocale house. Ten Meters long and it is a local scale house. 10,000 km long and your house is a planetary scale house!

Synoptic scale processes deal with storm systems like cold fronts and high pressure scales whose size is on the order of around 1000 km. The numerical weather prediction models we run every day are for the most part synoptic scale models.

Here in lies the problem with forecasting around here in the Summer. The models are synoptic scale but the processes that are effecting our weather each day right now are mesocale and even microscale processes.
Our weather models do a lousy job of predicting such things.

What I mean is this. The thunderstorms we have been having are not from a cold front. They are basically air mass storms and they form on mini cool fronts called out flow boundaries. We had an out flow boundary develop just south of some heavy storms in Tennessee Tuesday afternoon and that boundary came rapidly through Huntsville. When it did, we had a 12 degree temp. drop and the winds gusted out of the North up to 16 mph at the station. That boundary causes the air to lift and formed even more storms.

Many times these boundaries will form and persist for a day or two, setting off storms each day and getting modified by the cool air that forms as a result of the evaporational cooling.

They are very hard to detect on SYNOPTIC scale weather maps. May times we do see them light up on satellite images an hour or so before the storms develop. Not much lead time though.

As computers get faster and weather observations become more dense, we will see the development of mesocale models. A lot of research on this is going on right now. I may not live to see it but in a few decades, we will see a huge increase in the reliability of warm season forecasts in this part of the world.

These models are also thought to be a key to increased lead time for severe weather events.

For now though I will rely on the advice of one of my meteorology professors at OU. When I told him that I was going over tot he dark side and was planning on working in television, he said
“Tell them what you know and DON’T tell them what you don’t know!”

Best advice I ever received.

Later,
Dan