Weather Quiz

Hurricane Fred in the Eastern Atlantic Ocean   (Source: NOAA)

What is the busiest month of the hurricane season in the Atlantic Ocean?

A.  October

B.  August

C.  September

D.  November

---

Answer to the Weather Quiz question from August 20.

True.  Although only a hurricane for a short period of time, Danny became the first “major” hurricane of 2015 when it attained Category 3 status last week.  Fred was recently upgraded to a minimal hurricane in the eastern Atlantic Ocean becoming the second hurricane of 2015.  However, Fred isn't expected to grow into a major hurricane.

Hurricane Katrina and her Dangerous Sisters: A Look Back

Hurricane Katrina on August 28, 2005  (Source: NOAA)

This week’s 10^th anniversary of Hurricane Katrina’s infamous landfall along the U.S. Gulf Coast has dominated news headlines this week.  Hurricane Katrina was the second of four Category 5 hurricanes to develop during the record-setting 2005 season.  Fortunately, it weakened slightly to a Category 3 hurricane before making landfall.  However, the size and intensity of the storm which contributed to a catastrophic storm surge that was more characteristic of a Category 5 storm (which it was while over the open Gulf of Mexico), than the Category 3 storm it was at landfall. 

 

Katrina surpassed Hurricane Andrew as being the costliest natural disaster in U.S. history, causing an estimated $108 billion in damages.  Katrina was also the deadliest U.S. hurricane (having claimed nearly 1,800 lives) since the 1928 hurricane that devastated the Lake Okeechobee area in southern Florida, which claimed 2,500 lives.  The last “major” hurricane (Category 3 or higher on the Saffir-Simpson Hurricane Intensity Scale) to make landfall in the United States came in October 2005 when Hurricane Wilma made landfall as a Category 3 along the southwest coast of Florida.

I recently wrote about the busier-than-average 17 year period in the tropical Atlantic (from 1995 through 2012), when there were a series of significant storms that impacted the East Coast in late August and September.  For example, Hurricane Fran made landfall as a Category 3 hurricane in North Carolina on September 6, 1996.  It caused significant flooding and damage across much of the Mid-Atlantic Region with an estimated damage amount of $3.2 billion.

This week was also the fourth anniversary of Hurricane Irene’s landfall in the eastern United States.  It brought the DC Metro Region appreciable rainfall and high winds that made August 2011 the wettest August in the Nation’s Capital since 1967.  Ironically, this month has been one of the driest Augusts in recent memory.  

Currently, there are no active tropical storms or hurricanes anywhere in the Atlantic Ocean since Tropical Storm Erika dissipated this morning.  That means no short-term relief is likely from the recent dry weather pattern for the DC Metro Region. 

How has the Weather Treated Washingtonians this Summer?

Summer 2015 has been great for spending time outdoors !

Just like Charles Dickens’ famous work A Tale of Two Cities, this summer has been a tale of two extremes in the Nation’s Capital.  Starting June 1, the first six weeks of “meteorological” summer were both appreciably wetter and warmer than average at National Airport with a total of 15.43” of rain.  That’s more than the average rainfall from May through August combined in Washington, D.C.  Although June was the second wettest on record in Washington, D.C. (and that trend continued through mid-July), it’s remarkable how the weather pattern has taken a dramatic shift the other way since then.

Since July 14, a total of only 2.68” of rain had accumulated downtown.  August has been even drier, with only 1.16” of rain through yesterday.  Meanwhile, this summer has featured the highest number of 90 degrees days in the Nation’s Capital since 2012.  The National Weather Service replaced a faulty temperature sensor in the thermometer at National Airport earlier this month, but that doesn’t take away from the fact that weather conditions have been topsy-turvy in the Mid-Atlantic Region this summer.

May featured unseasonally warm weather in the Nation’s Capital and was also abnormally dry, with less than half of its average monthly rainfall.  That trend reversed itself dramatically from June 1 through July 13 when so much rain fell.  Meanwhile, this August has been a relatively quiet weather month in the Mid-Atlantic Region.  Washington, D.C.’s hottest temperature this month was 96 degrees.

Since this summer has featured the highest number of 90 degree days in Washington, D.C., since 2012 (45 days to date compared to an average of 36), it’s interesting to compare this month to 2012.  Although August 2012 had 15 days with temperatures of at least 90 degrees, this month has seen 12 such days through yesterday.  August 2012 was also slightly drier than average with 2.78” of rain, but that’s not as dry as this month has been so far with 1.16” at National Airport.  Unlike 2012 which featured an active hurricane season in the Atlantic Ocean, this tropical season has been fairly quiet so far.

The U.S. Climate Prediction Center is calling for equal chances of above or below normal temperatures and precipitation through the end of September in the Mid-Atlantic Region.  In fact, the weather for the rest of the week is actually looking quite stellar with near average temperatures in the mid to upper 80s and no chance of rain until later this weekend at the earliest.

Hurricanes: A Roll of the Dice?

The Tropical Atlantic Ocean Basin    Source: NOAA

Although Danny became the Atlantic’s first major hurricane of 2015 yesterday, the last few seasons have been relatively quiet in the tropical Atlantic.  That’s not unusual as periods of above and below average activity in the tropics tend to vacillate back and forth.  An active season or two by itself doesn’t mean very much, just like a quiet season or two doesn’t indicate a trend.

For example, the period from 1995 through 2012 was a very busy time in the tropical Atlantic as all but two seasons saw an above average number of named storms.  In fact, during this 17 year period there was a seasonal average of 16 tropical storms and 8.5 hurricanes, of which 4 became “major” hurricanes – Category 3 or higher on the Saffir-Simpson Hurricane Intensity Scale.  That’s appreciably higher than the seasonal average of 10 tropical storms and 6 hurricanes, including 2 – 3 major ones.

Multiple catastrophic hurricanes did make landfall in the United States during this above average period – including hurricanes Charley and Ivan in 2004, Katrina and Wilma in 2005 and Ike in 2008.  The Mid-Atlantic Region also saw multiple land-falling tropical systems during this period, including hurricanes Fran, Floyd, Isabel and Irene.  One of the most destructive storms to affect the U.S. during this active 17-year period was Sandy in late October of 2012.  Sandy remains the second costliest natural disaster in U.S. history.

Conversely, as busy as this period was, the 17-year stretch prior to 1995 was just as quiet.  By comparison, there was a seasonal average of only 9.7 tropical storms and 5.3 hurricanes with 1.7 major hurricanes from 1977 through 1994.  However, there were still a few destructive hurricanes during this period, such as Gloria, Hugo and Andrew.  According to the National Hurricane Center, Hurricane Andrew had been the costliest natural disaster in U.S. history until Katrina in 2005.

Meanwhile, there were eight Category 5 hurricanes in just the five-year period from 2003 through 2007.  That helps illustrate that tropical storm and hurricane frequency and intensity are cyclical, and therefore, prone to busier and quieter stretches.  Although events like El Nino and La Nina can cause a seasonal fluctuation above or below average, they don’t cause prolonged stretches of above or below average tropical activity.

The Atlantic Ocean Basin (including the Gulf of Mexico and Caribbean Sea) has been quieter than average since 2013.  Luckily no major hurricane has made landfall in the U.S. since Wilma in 2005.  This week will mark the 10^th anniversary of Hurricane Katrina’s landfall in Louisiana.  That memory should help people realize just how damaging and deadly a hurricane or tropical storm could be.  That’s why listening to your favorite meteorologists for the latest weather forecasts and heeding the advice of local authorities when a storm threatens your region is crucial.