Sunday, April 29, 2012

A New Tornado Tracker

Image Credit: NOAA.
According to the National Oceanic and Atmospheric Administration (NOAA), an average of 800 tornadoes are reported nationwide each year. The federal agency says as of April 29th there have been 588 tornadoes in 2012.  You already know that Doppler radar is used to detect tornadoes as they form.  Now there is another way to track tornadoes; through their reports.

Climate Central has just unveiled their new Tornado Tracker, an interactive map that lets you see not only where the twisters touched down last year, but where they are being reported now (it’s updated every 10 minutes around the clock), or on any date back to June 1, 2004. The example below shows the display for March 2, 2012, when there was an outbreak of tornadoes in the Southeast and Ohio River Valley: to get to the interactive version just click on the link.

Sunday, April 22, 2012

Summer 2012: A Burning Question

People are always asking me if the summer will be hot.  I tell them that this is Columbia, it is always hot.  I often add that the only thing that separates us from hell in the summertime is a screened door.

After this year’s amazingly mild winter, the obvious question is: will this summer be just as amazingly hot?  This is a question that I am already getting from viewers.  Keep in mind that the past two summers have each been record hot summers.  Common sense might say yes, an unusually warm winter will likely be followed by an unusually warm summer — but in this case, common sense would be wrong.

This chart shows the 10 mildest winters ever recorded at Metropolitan Airport, in blue, along with the summers that followed, in red. (This winter doesn’t appear at all, warm as it was, because the summer hasn’t happened yet.) And the answer is… there’s no pattern at all. A winter that’s warmer than average is sometimes followed by a warm summer, but sometimes it’s followed by a pretty average summer, or even an unusually cool one.

Click on the image to see a larger version, but for an interactive version of the graph click here.  Image Credit: Climate Central.
So what is in store for the Midlands this summer?

Wednesday, April 18, 2012

Weather Advances Do Not Happen Overnight

Dusan Zrnic. Image Credit: NSSL.
This is a repost of a story written by Bob Henson, who works at the National Center for Atmospheric Research (NCAR).  The original story can be found here and it has information about other advances in radar technology.  What is posted here is an excerpt of the history of dual-polarization with permission from the author.

By Bob Henson

The path to polarization

After years of development, the concept of polarizing radar signals for meteorology took root in the fertile soil of Canada’s Prairie provinces. NSSL’s Richard Doviak and Dusan Zrnić traveled to Alberta in 1979 to check out a circularly polarized radar pioneered by McGill University. “Dick had been interested in doing polarization research as early as 1971, but NSSL was deeply immersed in Doppler work at the time,” recalls Zrnić.

Once the lab decided to build its own polarized radar, it went for a dual-pol approach, with signals oriented in the horizontal or vertical rather than circularly. “We made this choice for good reason,” says Zrnić. Research by Thomas Seliga and Viswanathan Bringi, then both at Ohio State University, had shown how signals from the two orientations might yield critical data on the character of precipitation.

This hypothesis was confirmed through measurements in a 1977 Oklahoma field project using the CHILL dual-pol radar under the leadership of Gene Mueller. Now based at CSU, CHILL—the first university-based dual-pol radar—was named after Chicago, Illinois, where it was launched by the University of Chicago and the Illinois State Water Survey. NCAR was another dual-pol pioneer, converting its CP-2 radar and creating the first real-time displays of differential reflectivity (relating horizontal to vertical returns).

Starting in the mid-1980s, Zrnić teamed with postdoctoral fellows Mangalore Sachidananda (now at the Indian Institute of Technology) and Narasimha Balakrishnan (now at the Indian Institute of Science) to work out the details of distinguishing rain from hail and other hydrometeors using dual-pol data, with contributions from Jerry Straka (University of Oklahoma). By 1996, Zrnić had written a paper for the Bulletin of the American Meteorological Society pondering the eventual role of dual-pol in operational settings.

Monday, April 16, 2012

NWS Announces Significant Upgrade in Columbia, SC

The National Weather Service Forecast Office in Columbia, SC, announced today that the Doppler radar will be upgraded to dual polarization (or "dual-pol") beginning May 3rd.  It will take approximately a week for the upgrade during which time the radar will be inoperative.  Other area radars will be used to cover the Midlands in case of severe weather.  At News19 we will be using the Greenville, Atlanta, Wilmington, and Charleston radars in live mode to provide the coverage on the Max Storm Doppler Radar.  A composite radar will be used on our cable feed of the radar.

A minor inconvenience considering advantages of the system.   “This is the most significant upgrade to the nation’s weather radar network since Doppler radar was first installed in the early 1990s and is a significant step toward us becoming weather ready,” said Jack Hayes, director of NOAA’s National Weather Service. “Dual polarization technology provides significantly more information and clearer pictures of current weather conditions, helping National Weather Service meteorologists provide more accurate and timely forecasts."

A dual-pol radar at NOAA’s National Severe Storms Laboratory in Norman, Oklahoma, monitored this storm during the 2003 Thunderstorm Electrification and Lightning Experiment.  Image credit: Michael James, UCAR.

Friday, April 13, 2012

A Familiar Name From 2011 Retired

This is a repost from the National Hurricane Center.  A history of naming hurricanes and a list of retired names can be found here.

Click on image for a higher resolution. Image Credit: NOAA/NASA.
Irene has been retired from the official list of Atlantic Basin tropical storm names by the World Meteorological Organization’s (WMO) hurricane committee because of the fatalities and damage it caused in August 2011 and will be replaced by Irma.

Storm names are reused every six years for both the Atlantic Basin and eastern North Pacific Basin, unless retired for causing a considerable amount of casualties or damage. Irene is the 76th name to be retired from the Atlantic list since 1954.

Tuesday, April 10, 2012

Record March for the U.S.

March 2010 in Columbia, SC.  Image Credit: Climate Central.
Those of us in central South Carolina already know that this past March was the warmest on record.  I outlined the records in a previous post.  The graphic to the left covers the period since 1948.  The year of 1974 was the warmest during this time.  However, the records do extend back to 1888 and 1945 was the previous record.

The record warmth was not confined to central South Carolina.  Much of the central and eastern U.S. were part of this record breaking event.  March is usually a transitional month with weather systems progressing across the country producing a wide variety of weather conditions.

Image Credit: NOAA/NCDC.
However, this year was a year characterized by a ridge of high pressure in the East and a trough of low pressure in the West.  The chart to the left shows the mean 500 mb (about 18,000 feet in the atmosphere) heights and the height anomalies for the month.  The blue areas show where the heights were lower than normal and are related to the persistent troughs of low pressure.  The red areas correspond to above normal heights and are related to the areas of higher pressure.  This caused the jet stream to frequently dip far to the south along the West coast and then retreat north into Canada.

Saturday, April 7, 2012

Know Your Sun

Image Credit: NASA/Jenny Mottar
NASA has just released five new videos called "Mysteries of the Sun". The videos describe the science of the sun and its effects on the solar system and Earth. Scientists study the sun not only to better understand the orb that influences life, but also to study how it sends solar material out into space, filling up the bubble that defines the farthest reaches of the solar system. The sun can also impact Earth's technology: solar storms can affect our communications satellites and cause surges in power lines. These movies cover the breadth of solar, heliospheric, and geospace science, a field known as heliophysics.

The five movies, available online at and on DVD, cover five areas of heliophysics: Space Weather, Solar Variability, the Heliosphere, Earth's magnetosphere, and Earth's upper atmosphere.

Monday, April 2, 2012

A Record March for Columbia

If you thought it was warm in March, you were right.  Much of the U.S. east of the Rockies saw record or near record warmth for the first month of spring.  This follows the 4th warmest winter for the U.S. as a whole.  More information will be released from the National Climatic Data Center next week.

However, we do have the information for Columbia.  It was a record March for the city and not by just a small amount.  The average temperature for the month was 65.4 degrees beating the previous record of 64.7 set in 1945.  This was almost 10 degrees (9.8) above normal for the month.

Top 5 Warmest
Mean Temperature                       Year                         Temperature

Sunday, April 1, 2012

F. Sherwood Rowland: Scientist & Hero

Image Credit: Markos Possel Mapos
A few weeks ago word spread of the passing of F. Sherwood Rowland.  The first notice was a press release on the UC Irvine website.  He had an illustrious career as a chemist and won a Nobel Prize in Chemistry.  I never had the pleasure of meeting him, but there are few in meteorology that didn’t know of him.  Those who knew him can tell you more about his career and they can be found at Real Climate and Climate Progress.  Rowland was a member of the National Academy of Sciences where there is a wonderful tribute to him.

Rowland along with post-doctoral student Mario Molino found that chlorofluorocarbons (CFCs), a man-made substance, could be highly destructive to ozone.  One CFC could destroy up to 100,000 ozone molecules.  This could be damaging to the ozone layer even at concentration on the order of parts per billion.  The discovery led to their landmark paper published in Nature in 1974.

There were no observations at the time to confirm this, but it would not take long.  The first sign of trouble was reported by British scientists making measurements in the Antarctic.  Very low readings were being reported, but NASA could not confirm the observations from its satellite record.  A software glitch was found to be preventing NASA from seeing the low readings.  It turns out that the software was simply ignoring readings below 180 Dobson units, a measure of ozone concentration.

NASA was then able to confirm the British observations once the glitch was corrected and the data re-examined.  What they found was a tremendous hole in the ozone layer over the southern polar region.  The discovery sent shock waves through the scientific community and an international effort to study the phenomena was organized.