D.C.’s Late August Heat Waves

 

Sunrise from Charles Co., Maryland  (Photo Credit: Kristen Leitch)

Today will be the seventh day of D.C.’s current heat wave.  A “heat wave” is defined as a minimum of three consecutive days with highs in the 90s.  Although August is the second hottest month of the year in the Nation’s Capital, it gets harder to sustain the hot weather as the month wears on due to the decreasing sun angle and length of daylight.  Average daily high temperatures in Washington, D.C. fall from 89° as recently as August 11 to 86° less than three weeks later on August 27.  Nevertheless, there have been some memorable heat waves in the D.C. Metro Area this time of year in recent decades.

2022: Today is well-positioned to be the hottest day of D.C.’s current heat wave with highs approaching the mid-90s.  This the second longest heat wave of the summer behind an eight-day stretch from July 18 to July 25.  It is also D.C.’s longest heat wave to occur during the final 10 days of August since 1993.

2018: This was one of the rare instances that August was warmer than July in the Nation’s Capital with an average monthly temperature of 81.0° (combining daily high and low temperatures), compared to 80.7° in July 2018.  Appropriately, the month concluded with a five-day heat wave from August 27 – August 31.  The hottest day occurred on August 29 with a high/low of 94°/79° at National Airport.

2016:  Although not during the final third of the month, August 2016 was the last time Washingtonians experienced triple-digit heat, from August 13 – August 15.  August 2016 finished 0.1° behind August 1980 for D.C.’s hottest on record.

1998: High temperatures in the Nation’s Capital were in the 90s on all but one day from August 22 – August 31.  A record-tying high of 97° occurred on August 25.  The final 10 days helped catapult August 1998 to being D.C.’s hottest month of the year.  It would remain D.C.’s hottest August until 2002 when it was 100° twice and 99° twice.

1993: The 1993 summer was a hot one in the Nation’s Capital with multiple record highs.  Although some have since been broken, that doesn’t diminish the intensity of D.C.’s 1993 summer heat.  The final seven days of August 1993 saw the start of a 10-day heat wave that continued into September.  The hottest day was August 26 with a high and low temperature of 96°/77°.

2022: Hurricane Season Update

 

The Atlantic hurricane season spans six months of the year from June – November.  The first half of the 2022 season has been extremely quiet.  Not only have no named tropical storms developed in the Atlantic since Colin dissipated on July 3, but no hurricanes have developed yet this year.

That’s despite NOAA’s updated forecast earlier this month calling for a near average seasonal total of 14 – 20 tropical storms, of which 6 – 10 become hurricanes, with 3 – 5 “major” hurricanes.  An “average” Atlantic hurricane season has 14 tropical storms, 7 hurricanes and 3 major hurricanes.  A “major” hurricane is a Category 3 or greater on the Saffir-Simpson Hurricane Wind Scale with sustained winds of at least 111 mph.  Although it was initially expected to be another above average season, primarily due to an ongoing episode of La Nina, NOAA’s early August update to its seasonal forecast is less than what they were expecting earlier in the year.  

A significant amount of dry air and atmospheric dust has continued to pour into the tropical Atlantic from West Africa.  That’s helped create unfavorable conditions for development over a wide swath of the Atlantic.  As a result, the Atlantic has been as quiet as it’s been in decades.  2022 is the first season since 1982 that no named storms have occurred between July 2 and August 26 according to Colorado State University hurricane researcher, Dr. Philip Klotzbach.  It’s also only the fifth time that’s happened since 1950.  The last time the entire month of August has gone by with no named tropical storms was 1997. 

The 1997 Atlantic hurricane season, unlike this season, was expected to be a quieter than average one (it finished with 8 tropical storms, 3 hurricanes and 1 major Atlantic hurricane).  However, as recent seasons have shown, things in the tropical Atlantic can ramp up in a hurry.  The 2017 Atlantic hurricane season, for example, got markedly more active in late-August, starting with Hurricane Harvey.  September 2017 saw four major Atlantic hurricanes, including two Category 5 powerhouses (Irma and Maria). 

The 2020 Atlantic hurricane season had more named tropical storms than any season on record.  It was a back-loaded season with four major hurricanes after October 15.  That’s not to say this season will feature similar trends as 2017 or 2020, but atmospheric and environmental conditions are the most conducive for tropical development in September.  If current trends hold, then some impressive benchmarks for a quiet hurricane season will be met this season.

Remembering Deadly Hurricane Andrew

 

Category 5 Hurricane Andrew  (Source: NOAA)

“Andrew” will forever remain in infamy among Atlantic hurricanes.  It was 30 years ago on August 24 that Hurricane Andrew made landfall in south Florida as a Category 5 hurricane with sustained winds of 165 mph.  Having made landfall near Homestead, Florida (south of Miami), Andrew left unspeakable devastation in its path.  It was the first named storm of the 1992 Atlantic hurricane season and was also the only “major” hurricane (Category 3 or higher with sustained winds of at least 111 mph around the center of circulation) of the season.

Hurricane Andrew became the costliest natural disaster in U.S. history and caused roughly $27 billion in damages (unadjusted for inflation).  That’s an infamous distinction Andrew had until Hurricane Katrina 13 years later.  Andrew had a relatively compact size and fast rate of speed as it traveled across south Florida.  Its track south of Miami in combination with its relatively small wind-field (circumference of hurricane force winds) largely spared downtown Miami any significant impacts.  That was fortunate since as bad as Andrew was, it could have caused even more casualties than the 65 fatalities that occurred.

Hurricane Andrew occurred prior to the very active 1995 Atlantic hurricane season that represented a return to an active Atlantic hurricane cycle.  Prior to that, during the bulk of the 1970s through the early 1990s, the tropical Atlantic experienced many below average hurricane seasons.  However, as Andrew demonstrated, you don’t need to have an active season for it to be destructive or deadly. 

When Andrew made landfall as a Category 5 hurricane in Florida, it became only the third on record at the time to make landfall in the United States (along with the 1935 Florida Keys storm and Hurricane Camille in 1969).  Not only was Hurricane Andrew significant for its rare intensity at its time of landfall in Florida, but was also significant for when it occurred.  Florida’s coastal development and population increased significantly during the 1970s and 1980s when there were few direct impacts from tropical cyclones in Florida.  Unfortunately, it was documented after Andrew that Florida’s building codes in the 1970s and 1980s were inadequate.  That contributed to how destructive Hurricane Andrew was. 

Since then, building codes have not only been modernized but have been more stringently enforced.  This week’s focus during a quiet tropical Atlantic should be on the lessons learned from Hurricane Andrew on its 30^th anniversary.  Andrew remains one of the costliest natural disasters in U.S. history.