Remembering an early June Hurricane

Hurricane Allison on June 4, 1995  (Source: NOAA)

Although hurricane season began June 1 and continues through November 30, June and November are the two quietest months of the season.  That’s largely because atmospheric conditions and sea surface temperatures are generally unfavorable for widespread development in the tropics.  When tropical storms and hurricanes do form in June, the Gulf of Mexico and Caribbean Sea are where they typically develop since the water there warms up more quickly.  Tropical storms and hurricanes require ocean temperatures of at least 80 degrees to develop and intensify.

However, 1995 was one of the busiest hurricane seasons on record with 19 named tropical storms.  Of the 19 tropical storms that developed, 11 intensified into hurricanes according to the National Hurricane Center.  The first named storm of the very active 1995 season was Allison.  Allison was named a tropical storm (with maximum sustained winds of at least 39 mph) on June 3 while moving north from the western Caribbean Sea into the southeastern Gulf of Mexico.  Due to favorable conditions, Allison continued to intensify and became a minimal hurricane (with maximum sustained winds around its center of 75 mph) on this date 20 years ago. 

Hurricane Allison weakened slightly before making landfall in the Florida panhandle on June 5, 1995.  Although a relatively weak and fast moving storm, Hurricane Allison caused an estimated $1.7 million in damage.  According to the National Hurricane Center, Hurricane Allison was the earliest hurricane to form in the Atlantic Ocean since Bonnie became a Category 1 hurricane on June 25, 1986.  The most intense June hurricane on record remains Audrey in 1957. 

However, Hurricane Allison was overshadowed by the tropical storm of the same name that formed in 2001.  In 2001, Tropical Storm “Allison” also developed in June and brought Texas catastrophic flooding as more than 36” of rain fell in Houston with dozens of fatalities.  Allison remains the costliest tropical storm on record in U.S. history having caused more than $5 billion worth of damage in June 2001.  Allison also remains the only tropical storm to have its named retired by the World Meteorological Organization for being destructive and deadly.  The name “Andrea” replaced “Allison” in 2007.

Although the first named storm (Ana) of 2015 has already formed, NOAA is expecting a near or below average hurricane season in the Atlantic Ocean this year.

Just How Warm Was May 2015 in the Nation's Capital?

May is a beautiful time of year in the Nation's Capital

No sooner did we change the calendar to June than the relatively dry weather that dominated much of last month change.  And it changed dramatically with most of the DC Metro Region getting rainfall in excess of 1” to 3” yesterday and last night (Washington, D.C, and Baltimore, MD both set daily rainfall records yesterday).  

However, that doesn’t change the fact that May 2015 was not only one of the driest to occur over the last 20 years but was also the warmest on record in Washington, D.C.  To read more about how and why last month featured record warmth in the Nation’s Capital, check out this story I wrote for the WUSA9 website.

The 2015 Hurricane Season Gets Underway

Tropical Storm Ana (May 9, 2015)  Source: NASA

Today is the first day of the 2015 hurricane season in the Atlantic Ocean.  An average hurricane season features 10 named tropical storms, 6 hurricanes and 2 major hurricanes.  A system becomes a tropical storm when sustained winds around the center of the storm reach 39 mph.  A tropical storm becomes a hurricane when sustained winds reach 74 mph and a hurricane is classified as “major” once sustained winds reach at least 111 mph and it becomes a Category 3 on the “Saffir-Simpson” Hurricane Intensity Scale.  A system is given a name when it becomes a tropical storm.

NOAA recently released their forecast for the 2015 hurricane season.  They predicted 6 to 11 tropical storms, of which 3 to 6 will become hurricanes and 2 of those will become major hurricanes.  That would make 2015 an average or slightly below average season.  Tropical meteorologists at Colorado State University are also calling for a below average hurricane season in the Atlantic Ocean with only 7 tropical storms, 3 hurricanes and 1 major hurricane. 

NOAA cites the presence of El Nino as a primary factor for expecting an average or quieter than average season.  “El Nino” refers to the unusual warming of the tropical East Pacific Ocean off the west coast of Mexico and Central America.  This helps create unfavorable conditions in the tropical Atlantic including increased wind shear – or wind speeds that change direction with height. 

A quieter than average hurricane season doesn’t necessarily mean it won’t be a damaging or deadly hurricane season.  For example, although 1992 was a quieter than average hurricane season with only 7 tropical storms, it featured one of the worst hurricanes in U.S. history.  Hurricane Andrew was only the third Category 5 storm on record to make landfall in the United States when it came ashore in south Florida in August 1992.  Last season was also quiet in the Atlantic Ocean with 8 named tropical storms.  However, 2014 saw the Atlantic’s first Category 4 hurricane (Gonzalo) since 2011.

In a rare occurrence, the first tropical storm of the 2015 season already developed before this season officially began on May 8 when “Ana” was named.  Tropical Storm Ana made landfall in South Carolina.  June and July are typically quiet in the tropics as the ocean water continues to warm to the 80 degree threshold they require to develop.  Mid-August to Mid-October is typically the busiest period of the hurricane season.  Hurricane season ends on November 30.  NOAA will update their seasonal forecast in early August.

My colleagues and I on the WUSA9 Weather Team will keep viewers apprised of the latest weather conditions in the tropics both on-air and online.  The next tropical storm that develops will be named “Bill.”