Weather Quiz

Tropical Storm Bonnie nearing the SC Coast on May 28.  (Source: NASA)

Prior to 2016, when was the last time two named tropical storms developed prior to the official start of hurricane season on June 1?

A.  1995

B.  2005

C.  1951

D.  2012

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Answer to Weather Quiz question from May 19.

True.  Tropical storms have developed before June 1 in 2012, 2015 and 2016.

How Will this May be Remembered?

Just last Monday, Washingtonians were lamenting this May’s cool and wet weather.  However, May 2016 is no longer poised to finish among the Top 5 coolest on record in the Nation’s Capital following a week of warmer than average temperatures.  It will still finish up as one of the wetter Mays in recent memory.

Today could be the 20^th day of measureable rainfall this month in the Nation’s Capital – that would tie the monthly record from May 2003.  That includes a record streak of 15-consecutive days with measureable rain which ended on May 11.  The combination of clouds and rain helped suppress temperatures.  In fact, through May 22, the average temperature this month – combining daily highs and lows – was more than five degrees below average at 59.6 degrees.

However, there was a significant shift in the weather pattern last week that brought much of the eastern United States summer-like weather.  While Washington, D.C. enjoyed temperatures in the 80s over the past week, many cities in New England saw record warmth.  This past Saturday, May 28, Albany, NY, set a record high of 93 degrees, while Providence, RI also tied its record high of 91 degrees.

Area residents and tourists alike have enjoyed daily high temperatures in the 80s for the past week.  The warmest it’s officially been in the Nation’s Capital was 88 degrees on May 26 and May 27.  It hasn’t been 90 degrees or warmer in Washington, D.C. since it was 94 degrees on September 9, 2015.  Longtime residents know a day or two of 90-degree heat prior to the start of meteorological summer on June 1 is common in the Nation’s Capital.  Washingtonians have experienced at least one day of 90-degree heat in 15 of the 23 May’s since 1993.  May 2016 will, however, finish as the first May since 2013 without any 90-degree temperatures.

May 2016 will finish as the coolest since 2005 in Washington, D.C., with an average temperature – combining daily highs and lows – of 63.0 degrees.  By comparison, last May was the warmest on record in the Nation’s Capital with an average temperature of 73.2 degrees.  This May has also been the wettest since 2009 with 5.65” of rain.  Washingtonians can take satisfaction in their perseverance in getting through the cool and wet weather that dominated most of the month.

Memorial Day and Atlantic Hurricanes

Satellite view of the Atlantic Ocean Basin  (Source: NOAA)

The Memorial Day weekend symbolizes the unofficial start of summer and is the first major beach weekend of the season.  It’s also an important time for coastal residents to review safety procedures and preparedness for the upcoming hurricane season which runs from June 1 through November 30 in the Atlantic Ocean.  Although the majority of tropical storms and hurricanes form between mid-August and mid-October, there have been many significant storms that have occurred earlier in the year.

Named storms can also develop before hurricane season begins.  Such was the case this past January when Hurricane Alex developed.  Alex was the first January storm in the Atlantic since Alice in 1955.  Meteorologists at the National Hurricane Center are currently monitoring an area of disturbed weather near the Bahamas that has a good chance of becoming the next named tropical storm on the list, Bonnie.

Hurricanes and tropical storms are most frequent in August, September and October since that’s when conditions tend to be the most favorable with warm ocean water (sea surface temperatures of at least 80 degrees Fahrenheit is the common benchmark) and favorable winds in the tropics (namely light winds or an absence of wind shear).  Scientists look at global weather patterns for clues to how busy a given hurricane season will be.  For example, a powerful episode of El Nino helped make the 2015 hurricane season quieter than average in the Atlantic Ocean.  However, as El Nino dissipates, some suspect that 2016 will be a busier hurricane season in the Atlantic Ocean. 

While some respected groups – such as Colorado State University and Accu-Weather – have already issued their seasonal hurricane forecasts, NOAA is set to issue its forecast for the upcoming hurricane season today.  Only 7 tropical storms have developed in April or May since 1985.  History shows that having a named storm develop before hurricane season begins doesn’t always correlate to a busier than average hurricane season.  For example, Tropical Storm Ana developed in May 2015 but last season was appreciably quieter than average. 

People tend to hear more about early season tropical storms and hurricanes because they tend to form closer to land in the Gulf of Mexico and Caribbean Sea where ocean temperatures warm up more quickly.  The close proximity to land also means that they’re more likely to impact a given land mass.  Tropical Storm Beryl in May 2012 and Tropical Storm Allison in June 2001 both had significant impacts in the United States.  The key lesson as the Memorial Day holiday weekend gets underway is to stay tuned to your area meteorologists and local authorities whenever a tropical system poses a risk.

What Happened to Spring 2016?

A major shift in the weather pattern is underway following nearly a month of cooler and wetter than average weather in the Mid-Atlantic Region.  The Nation’s Capital has had measureable rainfall on 22 of the last 28 days – including a record 15-consecutive day stretch of rain that ended May 11.  Also, since May 1 there have been 18 days with measureable rainfall.

The frequent rainfall this month has helped suppress temperatures.  Through May 22, the average monthly temperature in the Nation’s Capital was 59.6 degrees, which was tied with May 1917 for second coolest on record.  Although average highs are in the 70s for most of May, there have been only eight days in the 70s so far this May.  By comparison, there were five days this month with high temperatures below 60 degrees – more characteristic of March.  Washington, D.C.’s record for most May days cooler than 60 degrees is seven – that last occurred in 1882! 

Such cooler than average May weather is almost unheard of in the Nation’s Capital.  May typically features several days with temperatures in the 80s and a few days in the 90s. Washingtonians have averaged between one and two days of 90-degree heat each May since 1993.  The last time it was 90 degrees in Washington, D.C. was when it was 94 degrees on September 9, 2015 according to the National Weather Service.

Despite the frequency of rain in the last month, the rainfall has been generally light.  Since May 1, there has been 5.22” of rain at National Airport, which wouldn’t even rank in the Top Ten among wettest Mays.  NOAA records indicate that on only four of the 22 days of rain since April 27, has there been a half an inch or more of rain.  Area residents are fortunate on two fronts: 1) there hasn’t been any significant flooding; and 2) the minor rainfall deficit from earlier this year no longer exists.

With the exception of a 12-day stretch last month, Washingtonians have languished in a painfully stubborn weather pattern that’s featured cooler and wetter than average conditions.  Residents and tourists haven’t been able to enjoy the city’s typically beautiful springtime weather.  While it hasn’t been 80 degrees in Washington, D.C. in almost a month since April 26, a rapid transition to a more summer-like pattern will occur as the Memorial Day weekend approaches. 

Temperatures will be around 80 degrees today and well into the 80s starting tomorrow and through the holiday weekend.  Some areas will approach 90 degrees by the end of the week.  That’s great news as area pools will open this weekend and many people head to the beach for Memorial Day.  By the time the hazy, hot and humid weather of mid-summer arrives, Washingtonians will fondly remember the cool and wet weather that’s dominated much of the last two months.

Revisiting a Terrible Tornado

Tornado track across Joplin, MO (May 22, 2011)

Today marks the fifth anniversary of one of the deadliest and most destructive tornadoes in U.S. history.  An EF-5 tornado occurred in the town of Joplin, Missouri on May 22, 2011 which caused an estimated $2.8 billion in damage.  Emergency officials determined it resulted in 158 fatalities, making it the deadliest single tornado to occur anywhere in the United States since modern tornado records began in 1950. 

This unusually intense tornado occurred in a highly populated area.  The EF-5 Joplin tornado was on the ground for approximately six miles, was three-quarters of a mile wide and had sustained winds greater than 200 mph.  The Joplin tornado was part of a larger severe weather outbreak that saw 75 tornadoes from Oklahoma to Wisconsin.  What made 2011 an unusual year was the number of intense tornadoes nationwide.  Scientists determined a total of six EF-5 tornadoes occurred, with another three borderline EF-4/EF-5 tornadoes.  NOAA also reported that the United States had its second highest number of tornadoes (1,691) in 2011, behind only 2004 (1,817). 

Tornadoes were originally measured on the Fujita Scale developed by the late-Dr. Ted Fujita of the University of Chicago.  It was updated or “enhanced” in 2007 and became the “Enhanced Fujita Scale.”  Wind speeds go from 65 – 85 mph in an EF-0 tornado to more than 200 mph in an EF-5 tornado.   The deadliest tornado on record in the U.S. was the “Tri-State Tornado” that occurred on March 18, 1925.  It tracked across three states including Missouri, Illinois and Indiana with a death toll of 695.  Unlike tropical storms and hurricanes, tornadoes are not given names but sometimes get nicknames if they are particularly intense or destructive. 

There have been dramatic changes in the science of meteorology since 1925.  Prior to the advent of weather radar during World War II, there was no way to track thunderstorms over any distance.  Weather satellites didn’t exist until the 1960s.  Since then, meteorologists have used both satellite and radar imagery in conjunction with improved computer forecasting models to issue more accurate weather watches and warnings.  That’s what makes the high fatality rate of the Joplin tornado so tragic.

Although there were a few minutes of advance warning in Joplin, it’s difficult to get large groups of people to safety in such a relatively short period of time.  Some have heard the myth that major cities don’t have tornadoes.  However, there have been many examples to the contrary over the last 20 years with tornadoes in Salt Lake City, Philadelphia, Minneapolis and Los Angeles.  The boroughs of Queens, Brooklyn and the Bronx in New York City even experienced weak tornadoes in 2010!

Fortunately, meteorologists and emergency planners have more and better tools to effectively communicate the latest weather watches and warnings.  Social media has made it so much easier to get the word out to the general public – including people who aren’t near a TV or radio.  Many weather apps also exists for smart phones and tablets that also enable people to stay informed when dangerous weather threatens.