Summer of 2014 - What Summer?

As meteorological summer – running from June 1 through August 31 – concludes, residents of the Mid-Atlantic will remember the 2014 summer for featuring little heat combined with an abundance of precipitation.  Overall, Washington, D.C., saw the fewest days of 90 degree heat since 2009 and no triple digit heat for a second consecutive summer.

Although June was slightly warmer and drier than average, there were only four days that featured temperatures at or above 90 degrees.  July was both cooler and wetter than average – a far cry from the summers of 2010 and 2012 that endured three of the hottest July’s on record in the Nation’s Capital.  This July featured only 9 days of high temperatures in the 90s.  By comparison, July 2011 experienced 25 days of temperatures 90 degrees or hotter and was the hottest July on record. 

August has continued the trend of being both cooler and wetter than average.  On only three occasions did the mercury climb to at least 90 degrees at National Airport – the official weather reporting site for the Nation’s Capital.  Compare that to August 2002, when there were 19 days in the 90s.  In nearby Virginia, Dulles Airport had only one 90 degree during the entire month of August, while seeing temperatures in the 50s on 10 different occasions – virtually unheard of in the Mid-Atlantic Region.  Also, several days featured heavy rain this summer with Baltimore (as measured at BWI Airport) setting a daily rainfall record of 6.30” on August 12.

Helping making the summer cooler and wetter than average was a persistent dip in the jet stream – a river of air in the atmosphere that guides storm track.  Our region was also fortunate not to feel the direct impact of any tropical systems.  There is no strong correlation between a cool and wet summer and a cold and snowy or warm and dry winter.  Other indicators such as the presence of El Nino or La Nina are what scientists look for in issuing their winter outlooks.

Weather Forecasting has Evolved and WUSA 9 Chief Meteorologist Topper Shutt Shares his Perspective

Topper Shutt, Chief Meteorologist of WUSA 9 in Washington, D.C., (the local CBS affiliate) has worked at Channel 9 since 1988.  Promoted to Chief Meteorologist in 2000, he has seen many changes in the science of meteorology and the art of broadcasting during his tenure in the Nation’s Capital.  I have worked alongside him the last few years assisting him in preparing weather graphics, updating the forecast on the station website and communicating the latest weather information to the public both on-air and online utilizing social media.
   

1.  What are some of the key differences you’ve noticed in broadcast meteorology during your tenure at WUSA 9 ?

I have witnessed a lot of changes in technology since I start in August of 1988. The modernization of the National Weather Service in 1990 included a nationwide Doppler radar system along with increased and improved computer forecast models.  That’s on top of vastly improved weather graphics system that enables us to tell the weather story.

 
2.  How large a role does social media play in your forecast?  Does social media add to your on-air segments?

Social media is huge. When there is severe weather we will push alerts out to our web site and smart phones before we go on the air or run a crawl on the air. Social media has enhanced our on air presentation. We now receive pictures of severe storms, damage and even tornadoes within minutes of their occurrence. Social media also has helped us with weather spotters in general. Now we have a fast way to engage viewers to get snow totals and storm damage.

3.  How large a split would you say there is between those people who watch you exclusively on-air vs. follow your forecasts online and through social media?

Research has shown that we reach more viewers on the social network platforms now, including Facebook, Twitter Vs. on air. On air viewers still outnumber our website users...for now.

 
4.  Do you expect to have greater viewership on air or online five years from now?

Definitely on line. Appointment TV is gone. Online viewership will surpass on air numbers as weather information must be available when viewers want it.

Andrew's Mean Streak

On this date in 1992, Hurricane Andrew made landfall in South Florida.  Andrew was the third of only three Category 5 hurricanes on record to make landfall in the United States.  The first two were the 1935 Labor Day hurricane that hit the Florida Keys and Hurricane Camille that struck the Gulf Coast in 1969.  Hurricanes didn’t start receiving names until 1950, so the 1935 hurricane is known as the “Labor Day” storm.

Being a Category 5 hurricane – as strong as hurricanes get on the Saffir-Simpson Hurricane Intensity Scale – Andrew caused unspeakable devastation in South Florida.  Hurricanes become a Category 5 when maximum sustained winds around the center or “eye” exceed 156 mph.  Andrew’s sustained winds at landfall – south of Miami near Homestead – were 165 mph.  Andrew made a second landfall along the Gulf Coast as a weaker Category 3 hurricane. 

Hurricane Andrew caused approximately $26.5 billion dollars in damage (adjusted for inflation) – making it the costliest natural disaster in U.S. history.  That’s a distinction Andrew had until Katrina in 2005.  Andrew is now the 4^th costliest natural disaster in U.S. behind Katrina, Hurricane Ike in 2008 and Sandy in 2012.  However, Andrew remains the last Category 5 hurricane to make landfall in the United States.

Unlike 22 years ago, there are no hurricanes in the Atlantic Ocean today.  Tropical Storm Cristobal is a weak storm with sustained winds of 45 mph bringing portions of Bahamas a lot of gusty winds, heavy rains and dangerous surf.  The storm is expected to veer northeast and not directly affect the U.S. East Coast.  However, some higher than normal surf and rip currents are likely this week across the East Coast due to the Tropical Storm.  So it is important to listen to local authorities about whether or not it’s safe to swim.  Cristobal should be gone before Labor Day weekend.

The Wind and Your Beach Vacation

Many of us head to the beach because the weather there is a welcome change from towns and suburbs.  Temperature differences of 10 degrees or more are common between the shore and inland areas, despite equal amounts of sunshine and being on the same latitude.

Why is this so?  The primary factor that causes such temperature spreads is the cycle of sea and land breezes at the beach.  Data from the University of Illinois shows that large bodies of water like a lake or ocean are able to absorb more energy from the sun without warming up as the land does.  We also know that warm air rises because it is lighter and less dense than cold air. 

So, when the warm air over the beach rises, cooler air over the water rushes in to replace the void created by the rising air.  This rush of cooler air is what is commonly referred to as the sea breeze, which beachgoers can feel on their faces as it blows inland.  The sea breeze is an added benefit of the shore providing people with relief from the heat even before they get in the water.  We can enjoy the cooling effects of the ocean while we are still setting up our beach umbrellas! In contrast, just a few miles inland from the beach – and away from the cooling effects of the sea breeze – it’s often unbearably hot. 

At night the opposite is true, since the land cools off more quickly than the sea.  When the relatively warm air over the ocean rises, the cooler air over the beach rushes in to fill the void created over water.  Those who enjoy going for walks on the beach at night benefit from this land breeze blowing on their backs. 

Something else significant happens at the beach when the warm air rises.  If it rises high enough in the atmosphere, it leads to the formation of those puffy, fair weather clouds that meteorologists call cumulus clouds.  During the day, these cumulus clouds form just inland due to the sea breeze and just offshore at night because of the land breeze.  Under the right circumstances, these cumulus clouds can grow into cumulonimbus clouds and give rise to a thunderstorm.

Sea and land breezes only occur during times of calm weather.  When a larger weather system such as an area of low pressure or front is in the vicinity, their associated weather supersedes the small scale phenomenon that’s exclusive to the beach.

Hazy, Hot and Humid

Although the average high for August 18 has cooled slightly to 87 degrees at National Airport, mid-August can still be quite hot.  On this date in 1995, Washington, D.C., set a record high of 97 degrees.   Like the summers of 2010-2012 that I wrote about recently, 1995 also featured an unusually hot summer (including a stretch of 25 consecutive days without measureable precipitation).

The 97 degree record high set 19 years ago today would stand for seven years until 2002, when the high climbed to a sultry 98 degrees.   Washingtonians experienced a rather unique occurrence in 2002 when August was hotter than July.  The average monthly temperature – combining daytime highs with nighttime lows - for August 2002 was 90.4 degrees, while it was “only” 89.7 degrees for July.  Also, August 2002 featured two days with triple digit heat (the first triple digit heat in the Nation’s Capital since July 1999).

The summers of 1995, 2002 and 2010-2012 saw a strong ridge of high pressure situated off the Southeast coast of the United States.  This high pressure ridge helped limit rainfall while pumping up the heat and humidity for the Mid-Atlantic Region.  However, the summers of 2013 and 2014 have not seen the same record heat and prolonged dry weather. 

In fact, the Mid-Atlantic Region had only 10 days of 90 degrees or hotter weather since July.  By comparison, from July 1 through August 18, 2010, Washington, D.C. (as measured at National Airport) observed 30 days of 90 degree or hotter high temperatures.  That helps illustrate the extreme variability in weather patterns in the Nation’s Capital – and makes forecasting the weather here challenging and exciting.

Forests Under Threat in the West

Western forests have experienced a myriad of weather conditions that have led to a significant amount of deforestation in recent years.  There has been an ongoing drought dating back more than a decade across much of the Western United States that has coincided with an uptick in wildfires and extreme heat waves.  In addition, heavy rain events have caused flash flooding and that threatened a lot of forest land.

Dating back to the late 1990s, a significant portion of the Western United States experienced worsening drought conditions.  That includes below normal snowfall during the winter months.  Snowfall has particular importance in the Rocky Mountains since the spring and summer snowmelt replenishes reservoirs.  The U.S. Drought Monitor Index continues to show severe to extreme conditions throughout the Southwest and California.

These circumstances have compelled residents to conserve water.  The climate is such out West that wildfires are an elevated risk because of dry underbrush and gusty winds.  Wildfires often begin innocently, by carelessly tossed cigarettes, campfires not properly extinguished and dry lightning strikes.  The U.S. Forest Service and the U.S. Department of the Interior are responsible for fighting wildfires across the country.  They concluded recently that they “may need to spend $1.8 billion fighting fires this year, while the agencies have only $1.4 billion available for firefighting.” 

Mountain pine beetles have also caused a considerable amount of damage to trees as far South as New Mexico and all the way North to Montana.   The pine beetles attack trees by laying their eggs and burrowing into the bark.  Once they hatch, the larvae grow and cause even more tree damage.  Recent winters have not been as cold in the Rocky Mountains as in decades past allowing pine beetles to survive and reproduce more quickly.

Due to the increasing amount of deforestation caused by drought, wildfires and pine beetles, flash flooding is an increased risk.  Exposed hillsides are less able to absorb water in a heavy rain than wooded areas are.  Although the summer monsoon season has helped ease drought conditions in the desert Southwest, it will take a more permanent shift in the overall weather pattern to end the chronic drought.  Like the Mid-Atlantic forests I recently wrote about, the forests in the Western United States contain an enormous amount of biodiversity and provide a natural way for the air to the cleanse itself.  That is why preventing deforestation is so important.