Haiyan or Yolanda?

One of the most powerful tropical cyclones on record hit the Philippines last Friday and then moved in southeast Asia over the weekend.  That storm was known as Typhoon Haiyan in international circles, but if you followed this event via the Internet, you may have noticed that some individuals were also referring to the storm as Typhoon Yolanda.  

Yolanda was the name given to the storm by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAG-ASA).  Any tropical system that has the potential to impact the Philippine islands the PAG-ASA assigns a Filipino sounding name, not necessarily names of people, to the storm to make it easier to be remembered.  The Philippines average around 20 named systems a year, far more than usually impact other countries in the world, making easily recognizable names very important for the country.  

Yolanda was the 24th system named this year by the PAG-ASA.

Orange Tornadoes

Last week on Halloween, 42 tornadoes were reported across the country.  Most of those were confirmed with storm survives over the following days.  That was the most tornadoes reported on October 31 since at least 1950.  That was also the highest daily tornado count in the United States since early July.  

Yet, even with a high number of tornadoes recorded last week, the 2013 season overall has been one of the quietest since good severe weather records started in 1950.  Not only has the tornado season been quiet, but so has the Atlantic hurricane season.  Through October the Accumulated Cyclone Energy (ACE) index was the 4th lowest since 1950 for the Atlantic basin.  

Plus, it will probably be another year without a major hurricane strike on the lower 48 states, continuing the longest such streak since at least the Civil War.

ACE is the Word

A widely used tool for analyzing the strength of a hurricane season is the Accumulated Cyclone Energy or ACE index.   The ACE index combines the number, strength and duration of tropical systems into a set mathematical equation.  This can give a much better insight into the differences between tropical seasons rather than just counting the number of storms alone.

For instance, although the North Atlantic Hurricane season has now recorded 11 named systems, the accumulated ACE score for the year is running at less than 30% of average.  The average is based on the years 1981 through 2010.  The North Atlantic basin is not the only region recording well below normal ACE scores this year.  In fact, globally, all tropical regions are running below normal for ACE scores.  Taken as a whole, global ACE numbers this year are running at only 54% of average.  

The past several years have also recorded a below average ACE, likely attributed to a recent switch to cooler Pacific Ocean temperatures. 

Lack of Majors

The last time the United States was struck by a major hurricane (Category 3,4 or 5) was on October 19, 2005 when Wilma impacted Florida.  2005 was an exceptionally busy year for land falling hurricanes in the country.  This current period without a major hurricane hitting the lower 48 states is the longest since at least the Civil War. 

Some may say we are “overdue” for a major hurricane to hit somewhere in the country, but of course, the atmosphere does what it does and through the centuries periods of active and less active stretches have always occurred.  Back in 1954 the east coast recorded three major hurricanes in less than 10 weeks, which is no more abnormal than our current stretch of nearly eight years without a major hurricane.   

As we learned with Hurricane Sandy just last year, it does not take a major hurricane to cause horrific damage along the heavily populated coastal areas of the United States.  The streak will eventually end and it could easily do so yet this year. 

George Washington’s Hurricane

On July 23-24, 1788 a hurricane moved through the Mid-Atlantic States.  That storm is often referenced as the George Washington Hurricane as it was mentioned in his diary.  As the storm approached Virginia from the east, the wind began to pick up considerably from the northeast on July 23.  Then in the very early hours of July 24 the wind quickly and suddenly shifted to the south and “blew a perfect hurricane, tearing down chimneys and fences”.

That shifting wind from the northeast to the south indicates that eye of that particular hurricane passed right over Mt. Vernon.  The storm caused extensive flooding with many drowning victims reported.  Also, extensive crop damage was reported with several ships driven on shore.  Plus, Washington mentioned that a small ship, The “Federalist” sank during the storm.

From the descriptions of others who also wrote of this storm in their diaries, Mt. Vernon fared better than others, as James Madison, father of the future president said the damage was “beyond description” in  Alexandria, Virginia.

June Drought

Although the Atlantic hurricane season begins on June 1, land falling hurricanes during the first month of the season in the United States are quite rare.  There has not been a direct hit on the United States by a hurricane in the month of June since Bonnie came on shore near the Texas/Louisiana border on June 26, 1986. 

Numerous tropical storms have impacted the country in June, including Andrea this year, but hurricanes are the exception rather than the rule this early in the year.  Previous to Bonnie in 1986, other more recent hurricanes to have impacted the United States in June include Agnes in 1972, Alma in 1966 and Audrey in 1957.  Audrey was the most powerful land falling hurricane during the month of June since records have with peak wind estimated at 145 mph. 

The June with the most land falling hurricanes occurred back when Grover Cleveland was president.  In June 1886 three hurricanes impacted the country, the only June on record with more than one hurricane striking the country. 

Hurricane Season 2013

Today marks the beginning of the Atlantic Hurricane season.  The tropical season in the northern Atlantic runs from June 1 through November 30.  Although tropical systems have and can develop outside of that time period, a vast majority of tropical systems do develop during those six months.  Hurricane Sandy continues to make news to this day as coastal residents in New Jersey and New York continue to recover, but overall, the United States have been in a hurricane drought for the past several years. 

Florida for instance has gone seven years without a land falling hurricane and the United States as a whole has not had a major Hurricane (Category 3 or higher) come on shore since 2005.  Both of those are the longest such periods since at least the Civil War.  This upcoming tropical season has potential to be a busy with many factors coming into play favorable for hurricane development, meaning, those streaks could unfortunately come to an end this year.

Evan

In the Atlantic Ocean they are called hurricanes.   In the western Pacific they are referred to as typhoons.  In the southern Pacific and in the Indian Ocean they are referenced as tropical cyclones.  The tropical cyclone season is just beginning and already one has brought devastation.

Somoa and neighboring American Somoa were hit last week by Tropical Cyclone Evan.   Evan was a Category 2 Tropical Cyclone when it made a direct hit on Upolu, the eastern of the two principle islands of Somoa.  It then moved northeast with the eye wall just missing American Somoa and then it stalled and moved back toward Somoa with the eye wall barely missing them again.  That track kept high wind and torrential rainfall over the area for a few days. Tragically at least three deaths were attributed to Evan with two of those deaths being young children.

The storm then intensified into a Category 4 storm and headed southwest and had major impacts on Fiji on Monday.

The Static Illusion

There is no denying that Sandy caused horrific damage to the east coast.  Although many people were surprised that such an event hit where it did, most meteorologists on the other hand were instead surprised that area was not hit again sooner.  In this space and during many of my public talks I have mentioned that our weather patterns in recent years have transitioned to what occurred in the 1950s and 1960s.

The 1950s recorded several hurricane strikes along the east coast with many causing devastation on par with Sandy.  With a much higher population base in combination with increased land use changes along the coast, although exceptionally heart breaking to see, the amount of damage was not unexpected.

Until humans realize that the boundary between land and ocean (or lake and rivers) is not static we are going to continue to experience such destruction in the future, as if we want to admit it or not, the forces of nature can not be controlled.

The Typhoon Did It

When Hurricane Isaac was moving toward the United States, several individuals emailed and asked if it would have any impact on us locally. Historically, it has been rare for the remnants of a hurricane or tropical system to bring rainfall into this area.  Instead of getting rain from a tropical system, a hurricane may help alter the upper level wind flow to temporarily adjust the pattern that would influence our weather in that manner.

That is particularly true with western Pacific typhoons.  Powerful typhoons in particular often help form a large ridge of high pressure to their east, which induces the formation of an area of low pressure and a corresponding trough east of that ridge in the Aleutian Islands.  That storm in turn tends to advect warmer Pacific air into Alaska.   The colder air over Alaska is then forced south into the lower 48 states impacting areas east of the Rocky Mountains in particular.

In some ways, typhoons in the Pacific can alter our weather more than their hurricane cousins in the Atlantic.