Just Another Number?

Numbers have meaning only in context.  A temperature of 98.6 degrees F is normal body temperature, but only in context of the mean.  This is not normal for every person.  The S&P 500 crossing 1600 is meaningless unless it is in context of what the market is doing.  Is it going up or down?  How far has it gone from previous levels?  Only then does the number have meaning.

A milestone was reached recently, Thursday, May 9^th, at the Mauna Loa Observatory in Hawaii.  Levels of carbon dioxide reached 400 parts per million (ppm) for the first time in human existence.  Daily measurements are made at the observatory of the gases that lead to atmospheric change.  One of the main gases monitored is carbon dioxide (CO2).  Levels of 400.03 and 400.08 ppm were measured independently by the National Oceanic & Atmospheric Administration (NOAA) and Scripps Oceanographic Institute respectively.

Mauna Loa Observatory in Hawaii.  Click on the image for a larger version.  Image Credit: NOAA/ESRL.

This was a daily mean that was measured for the first time.  Hourly measurements exceeded this number quite a few times since mid-April.  The monthly mean of CO2 will likely peak this month, at a level of about 399 ppm, and then fall until October.  It is likely to pass the 400 ppm in the spring of next year.  The yearly mean will not likely cross this level until 2015 or 2016.

A Drought Worth Having

Droughts can be quite nasty with it comes to rainfall.  However, droughts can be a good thing when it comes to severe weather.  The U.S. is currently experiencing such a drought for tornadoes.

The monthly number of tornadoes for 2013 compared to the 1981-2010 average. Click on the image for a larger version.  Image Credit: Climate Central.

The year started off looking above normal, but that quickly turned in February.  Significantly fewer tornadoes were observed in March and April.  May is normally the peak of tornado season for much of the country.  The drought has continued and will likely continue into the middle of May.  It is hard to say if it will continue beyond that, but it is likely.

A Cool Start To May 2013

Just as we were getting used to hotter springs, Mother Nature pulls a fast one.  It has been unusual to say the least for South Carolina weather since April 26^th.  Cloudy, cool conditions have been the rule with plenty of rain.  The griping has begun as many are tied of conditions we normally attribute to Seattle.

My favorite tweet during the past week has been “Breaking news: This just in – Cleveland wants its weather back.”  I’m sure those in Cleveland might think this an improvement over what they normally get in early May.

So what has been happening?  Why has it been so cloudy and cool for so long?  When will this go away so that we can get on with summer?

The first half of spring was influenced by a weather pattern associated with a negative phase of the Arctic Oscillation.  This was described in the previous post.  However, that has not driving the weather pattern recently.  Instead the jet stream has retreated to the north leaving upper-level low pressure systems isolated from the main flow.  This has resulted in a blocking pattern where weather systems slow to a crawl and can persist for days.

The weather pattern at 500 mb (~18,000 ft) on Saturday, May 4, 2013 at 12z UT.  The jet stream had retreated farther to the north leaving isolated pockets of low pressure over the mid-latitudes.  Click on the image for a larger version.  Image Credit: WLTX-TV.

A Dramatic Change This Spring

It is amazing how fast the weather pattern can change.  Temperatures were much below normal at the end of March.  There was a brief warm up at the beginning of April, but a brief cool snap followed.  Finally the cold air retreated leaving much of South Carolina with above normal temperatures.  In a matter of five days high temperatures in Columbia went from 55 degrees F on April 4^th to 87 degrees F on April 9^th & 10^th.

A previous post talked about the delay of spring this year.  High pressure centered near Greenland continued to pump cold Arctic air south into North America.  This was part of the negative phase of the Arctic Oscillation which became extreme in March.  This led to colder temperatures in March than in January.

This image shows the sea level pressure anomaly calculated from NCEP climate reanalysis data from February 25 through March 25, 2013. The area of anomalous high pressure over Greenland illustrates the negative phase of the Arctic Oscillation, by which persistent high pressure blocks Arctic air from moving eastward, causing it to drop down into the middle latitudes and is a contributing factor in keeping temperatures unseasonably cool in Canada and the US.  Click on the image for a larger view.  Image Credit: NOAA.

When Weather Becomes Climate

Note: It has been a busy three weeks which included a week of much needed vacation.  Much has happened in the interim.  I am working on a number of posts which will be rolled out in May.

Meanwhile, many people often confuse weather with climate.  You have heard the refrains like it is so cold, how could the earth be warming?  Or how can we be in a drought when we’re having a flood?  Just when does weather become climate?  Good question!  Meteorologists at the European Space Agency have produced an answer to that question.

The following video is about 12 minutes long, but it is well produced and worth the time to view it.  They have a wealth of information with which to determine climate change and it is interesting comparing weather in the early 1800’s to weather today.  I hope you enjoy this production.

Click here: When Weather Becomes Climate

ISS: Double Pass This Weekend

Finally the weather is improving and time to get outside and enjoy spring.  This weekend offers the opportunity to see the International Space Station (ISS) pass over the area twice.  Both passes will be excellent and highly visible without the aid of binoculars.

ISS streaks across the sky.  Image Credit: Andreas Möller.

The first opportunity to see ISS will be Saturday evening.  If you have an unobstructed view of the southwest horizon, you will be able to see it rise immediately beginning at 9:27 p.m.  Most will be able to see ISS by 9:30 p.m. in the southwest moving toward the northeast.  About a minute later it will pass through the constellation Orion.  You might want to try taking a time exposed picture.  It will reach its maximum altitude at 9:32:52 p.m. about two-thirds above the northwest horizon.  However, just 17 seconds later it will move into the earth’s shadow and disappear.  If you are in a dark environment, this can be quite interesting to watch.

Spring 2013: DELAYED

It’s spring!

The vernal equinox on March 20, 2013.  It is that time of year again (it happens twice) when the relative angle of Earth is perpendicular to the Sun, causing equal incoming solar energy to the Northern and Southern hemispheres - as well as equal day and nighttime. At 7:02 ET on March 20, 2013, Earth was at its equinox. At 7:45 ET, the GOES-13 satellite captured this full disk image of Earth.  Click on the image for a larger view.  Image Credit: NOAA.

Both meteorological and astronomical springs have arrived.  The vernal equinox marks the beginning of spring in the Northern Hemisphere.  This is when the vertical rays of the sun are directly over the earth’s equator and crosses the equator on its northward journey.

Funny, it doesn’t feel like spring.  Let me check the forecast:

The 5-day forecast for March 20, 2013 for Columbia, SC.  Image Credit: WLTX-TV.

Remember those groundhog forecasts from six weeks ago.  A couple of them got it right, but most got is wrong.  Not only did spring not come early, it does not appear to be in sight.

Energy And Climate

The 2013 annual meeting of the American Meteorological Society took place this past January in Austin, Texas.  One of the topics was that of energy and climate.  Billionaire T. Boone Pickens spoke on Sunday evening before the annual meeting began.  It was an enjoyable evening and interesting to hear was he had to say.

T. Boone Pickens

First, he holds a degree in geology from Oklahoma State University.  Pickens said “I’m one of the few (petroleum) geologists that agree that global warming is happening.”  He agrees that we need to do something to mitigate the effects of the warming.  It is smarter to do something to avoid the problem rather than waiting until it happens to do anything.

However, he went on to say that hydrocarbons (fossil fuels) would be with us for the next 50 years.  Pickens said that wind and solar represent just 2% of the energy generation and he didn’t think that it would become substantial until it became economically more competitive with fossil fuels.  That means a price of about $6 for natural gas (it is just under $4 today).

Pickens is against the idea of a carbon tax or cap & trade.  However, he did not say whether he agreed with the idea of ending fossil fuel subsidies.  Tom Friedman of the New York Times has an interesting article on attacking carbon emissions and the fiscal debt.

Comet PANSTARRS

Comets bright enough to be seen without the aid of a telescope or binoculars are a rarity.  This year may produce two such events.  The first is now visible in the western sky after sunset, weather permitting.  Comet PANSTARRS is actually Comet 2011 L4.  Discovered in June 2011, comet 2011 L4 (PANSTARRS) bears the name of the telescopic survey that discovered it; "Panoramic Survey Telescope and Rapid Response System" which sits atop the Haleakala volcano in Hawaii.

The comet moved into the view of the Northern Hemisphere last week, but the best views should be over the next two weeks.  You can follow continuing updates on the progress of the comet at Sky and Telescope.  Viewing the comet may still be a challenge.

Comet C/2011 L4 PANSTARRS as seen from Mount Dale, Western Australia. The lights on the distant horizon are from the city of Armadale, which is southeast of Perth. Click on the image for a larger view. Image credit: Astronomy Education Services/Gingin Observatory.

Southeast Drought Improves

What a difference a month can make.  The drought situation was becoming serious at the end of January as I wrote here.  Yet, February saw an abundance of rainfall creating a substantial surplus for the month.

Monthly rainfall for February in Columbia, SC.  Image Credit: WLTX-TV.

Monthly observed rainfall for February, 2013, covering South Carolina as well as parts of Georgia and North Carolina.  Click on the image for a larger view.  Image Credit: NOAA/AHPS.

In South Carolina the heaviest rainfall occurred over the southern half of the state.  Some parts of the low country saw over ten inches of rain for the month.  The least rainfall occurred over the north central section where rainfall was in the three to four inch range.  However, this area saw more rain in January so that the two-month total is substantial.

A series of storm systems moved through the Southeast pumping moisture from the Gulf of Mexico northward.  The heaviest rainfall occurred across southern Alabama, southern Georgia, and parts of northern Florida.  The drought was center in central Georgia which had experienced extreme to exceptional drought conditions for over a year and a half.